siginfo_t ABI break on sparc64 from si_addr_lsb move 3y ago

siginfo_t ABI break on sparc64 from si_addr_lsb move 3y ago

[Marco Elver]

Hello,  Eric,

By inspecting the logs I've seen that about 3 years ago there had been a
number of siginfo_t cleanups. This included moving si_addr_lsb:

	b68a68d3dcc1 ("signal: Move addr_lsb into the _sigfault union for clarity")
	859d880cf544 ("signal: Correct the offset of si_pkey in struct siginfo")
 	8420f71943ae ("signal: Correct the offset of si_pkey and si_lower in struct siginfo on m68k")

In an ideal world, we could just have si_addr + the union in _sigfault,
but it seems there are more corner cases. :-/

The reason I've stumbled upon this is that I wanted to add the just
merged si_perf [1] field to glibc. But what I noticed is that glibc's
definition and ours are vastly different around si_addr_lsb, si_lower,
si_upper, and si_pkey.

[1] https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=42dec9a936e7696bea1f27d3c5a0068cd9aa95fd

In our current definition of siginfo_t, si_addr_lsb is placed into the
same union as si_lower, si_upper, and si_pkey (and now si_perf). From
the logs I see that si_lower, si_upper, and si_pkey are padded because
si_addr_lsb used to be outside the union, which goes back to
"signal: Move addr_lsb into the _sigfault union for clarity".

Since then, si_addr_lsb must also be pointer-aligned, because the union
containing it must be pointer-aligned (because si_upper, si_lower). On
all architectures where si_addr_lsb is right after si_addr, this is
perfectly fine, because si_addr itself is a pointer...

... except for the anomaly that are 64-bit architectures that define
__ARCH_SI_TRAPNO and want that 'int si_trapno'. Like, for example
sparc64, which means siginfo_t's ABI has been subtly broken on sparc64
since v4.16.

The following static asserts illustrate this:

--- a/arch/sparc/kernel/signal_64.c
+++ b/arch/sparc/kernel/signal_64.c
@@ -556,3 +556,37 @@ void do_notify_resume(struct pt_regs *regs, unsigned long orig_i0, unsigned long
 	user_enter();
 }
 
+static_assert(offsetof(siginfo_t, si_signo)	== 0);
+static_assert(offsetof(siginfo_t, si_errno)	== 4);
+static_assert(offsetof(siginfo_t, si_code)	== 8);
+static_assert(offsetof(siginfo_t, si_pid)	== 16);
+static_assert(offsetof(siginfo_t, si_uid)	== 20);
+static_assert(offsetof(siginfo_t, si_tid)	== 16);
+static_assert(offsetof(siginfo_t, si_overrun)	== 20);
+static_assert(offsetof(siginfo_t, si_status)	== 24);
+static_assert(offsetof(siginfo_t, si_utime)	== 32);
+static_assert(offsetof(siginfo_t, si_stime)	== 40);
+static_assert(offsetof(siginfo_t, si_value)	== 24);
+static_assert(offsetof(siginfo_t, si_int)	== 24);
+static_assert(offsetof(siginfo_t, si_ptr)	== 24);
+static_assert(offsetof(siginfo_t, si_addr)	== 16);
+static_assert(offsetof(siginfo_t, si_trapno)	== 24);
+#if 1 /* Correct offsets, obtained from v4.14 */
+static_assert(offsetof(siginfo_t, si_addr_lsb)	== 28);
+static_assert(offsetof(siginfo_t, si_lower)	== 32);
+static_assert(offsetof(siginfo_t, si_upper)	== 40);
+static_assert(offsetof(siginfo_t, si_pkey)	== 32);
+#else /* Current offsets, as of v4.16 */
+static_assert(offsetof(siginfo_t, si_addr_lsb)	== 32);
+static_assert(offsetof(siginfo_t, si_lower)	== 40);
+static_assert(offsetof(siginfo_t, si_upper)	== 48);
+static_assert(offsetof(siginfo_t, si_pkey)	== 40);
+#endif
+static_assert(offsetof(siginfo_t, si_band)	== 16);
+static_assert(offsetof(siginfo_t, si_fd)	== 20);

---

Granted, nobody seems to have noticed because I don't even know if these
fields have use on sparc64. But I don't yet see this as justification to
leave things as-is...

The collateral damage of this, and the acute problem that I'm having is
defining si_perf in a sort-of readable and portable way in siginfo_t
definitions that live outside the kernel, where sparc64 does not yet
have broken si_addr_lsb. And the same difficulty applies to the kernel
if we want to unbreak sparc64, while not wanting to move si_perf for
other architectures.

There are 2 options I see to solve this:

1. Make things simple again. We could just revert the change moving
   si_addr_lsb into the union, and sadly accept we'll have to live with
   that legacy "design" mistake. (si_perf stays in the union, but will
   unfortunately change its offset for all architectures... this one-off
   move might be ok because it's new.)

2. Add special cases to retain si_addr_lsb in the union on architectures
   that do not have __ARCH_SI_TRAPNO (the majority). I have added a
   draft patch that would do this below (with some refactoring so that
   it remains sort-of readable), as an experiment to see how complicated
   this gets.

Option (1) means we'll forever be wasting the space where si_addr_lsb
lives (including the padding). It'd also mean we'd move si_perf for
_all_ architectures -- this might be acceptable, given there is no
stable release with it yet -- the fix just needs to be merged before the
release of v5.13! It is the simpler option though -- and I don't know if
we need all this complexity.

Option (2) perhaps results in better space utilization. Maybe that's
better long-term if we worry about space in some rather distant future
-- where we need those 8 bytes on 64-bit architectures to not exceed 128
bytes. This option, however, doesn't just make us carry this complexity
forever, but also forces it onto everyone else, like glibc and other
libcs (including those in other languages with C FFIs) which have their
own definition of siginfo_t.

Which option do you prefer? Are there better options?

Many thanks,
-- Marco

------ >8 ------

Option #2 draft:

diff --git a/arch/sparc/kernel/signal_64.c b/arch/sparc/kernel/signal_64.c
index a0eec62c825d..150ee27b1423 100644
--- a/arch/sparc/kernel/signal_64.c
+++ b/arch/sparc/kernel/signal_64.c
@@ -556,3 +556,37 @@ void do_notify_resume(struct pt_regs *regs, unsigned long orig_i0, unsigned long
 	user_enter();
 }
 
+/*
+ * Compile-time assertions for siginfo_t offsets. Unlike other architectures,
+ * sparc64 is special, because it requires si_trapno (int), and the following
+ * si_addr_lsb (short) need not be word aligned. Accidental changes around the
+ * offset of si_addr_lsb and the following fields would only be caught here.
+ */
+static_assert(offsetof(siginfo_t, si_signo)	== 0);
+static_assert(offsetof(siginfo_t, si_errno)	== 4);
+static_assert(offsetof(siginfo_t, si_code)	== 8);
+static_assert(offsetof(siginfo_t, si_pid)	== 16);
+static_assert(offsetof(siginfo_t, si_uid)	== 20);
+static_assert(offsetof(siginfo_t, si_tid)	== 16);
+static_assert(offsetof(siginfo_t, si_overrun)	== 20);
+static_assert(offsetof(siginfo_t, si_status)	== 24);
+static_assert(offsetof(siginfo_t, si_utime)	== 32);
+static_assert(offsetof(siginfo_t, si_stime)	== 40);
+static_assert(offsetof(siginfo_t, si_value)	== 24);
+static_assert(offsetof(siginfo_t, si_int)	== 24);
+static_assert(offsetof(siginfo_t, si_ptr)	== 24);
+static_assert(offsetof(siginfo_t, si_addr)	== 16);
+static_assert(offsetof(siginfo_t, si_trapno)	== 24);
+#if 1 /* Correct offsets, obtained from v4.14 */
+static_assert(offsetof(siginfo_t, si_addr_lsb)	== 28);
+static_assert(offsetof(siginfo_t, si_lower)	== 32);
+static_assert(offsetof(siginfo_t, si_upper)	== 40);
+static_assert(offsetof(siginfo_t, si_pkey)	== 32);
+#else /* Current offsets, as of v4.16 */
+static_assert(offsetof(siginfo_t, si_addr_lsb)	== 32);
+static_assert(offsetof(siginfo_t, si_lower)	== 40);
+static_assert(offsetof(siginfo_t, si_upper)	== 48);
+static_assert(offsetof(siginfo_t, si_pkey)	== 40);
+#endif
+static_assert(offsetof(siginfo_t, si_band)	== 16);
+static_assert(offsetof(siginfo_t, si_fd)	== 20);
diff --git a/include/linux/compat.h b/include/linux/compat.h
index f0d2dd35d408..5ea9f9c748dd 100644
--- a/include/linux/compat.h
+++ b/include/linux/compat.h
@@ -158,6 +158,31 @@ typedef union compat_sigval {
 	compat_uptr_t	sival_ptr;
 } compat_sigval_t;
 
+struct __compat_sigfault_addin {
+#ifdef __ARCH_SI_TRAPNO
+	int _trapno;	/* TRAP # which caused the signal */
+#endif
+	/*
+	 * used when si_code=BUS_MCEERR_AR or
+	 * used when si_code=BUS_MCEERR_AO
+	 */
+	short int _addr_lsb;	/* Valid LSB of the reported address. */
+
+/* See include/asm-generic/uapi/siginfo.h */
+#ifdef __ARCH_SI_TRAPNO
+#	define __COMPAT_SIGFAULT_ADDIN_FIXED struct __compat_sigfault_addin _addin;
+#	define __COMPAT_SIGFAULT_ADDIN_UNION
+#	define __COMPAT_SIGFAULT_LEGACY_UNION_PAD
+#else
+#	define __COMPAT_SIGFAULT_ADDIN_FIXED
+#	define __COMPAT_SIGFAULT_ADDIN_UNION struct __compat_sigfault_addin _addin;
+#	define __COMPAT_SIGFAULT_LEGACY_UNION_PAD				\
+		char _unused[__alignof__(compat_uptr_t) < sizeof(short) ?       \
+				   sizeof(short) :				\
+				   __alignof__(compat_uptr_t)];
+#endif
+};
+
 typedef struct compat_siginfo {
 	int si_signo;
 #ifndef __ARCH_HAS_SWAPPED_SIGINFO
@@ -214,26 +239,18 @@ typedef struct compat_siginfo {
 		/* SIGILL, SIGFPE, SIGSEGV, SIGBUS, SIGTRAP, SIGEMT */
 		struct {
 			compat_uptr_t _addr;	/* faulting insn/memory ref. */
-#ifdef __ARCH_SI_TRAPNO
-			int _trapno;	/* TRAP # which caused the signal */
-#endif
-#define __COMPAT_ADDR_BND_PKEY_PAD  (__alignof__(compat_uptr_t) < sizeof(short) ? \
-				     sizeof(short) : __alignof__(compat_uptr_t))
+			__COMPAT_SIGFAULT_ADDIN_FIXED
 			union {
-				/*
-				 * used when si_code=BUS_MCEERR_AR or
-				 * used when si_code=BUS_MCEERR_AO
-				 */
-				short int _addr_lsb;	/* Valid LSB of the reported address. */
+				__COMPAT_SIGFAULT_ADDIN_UNION
 				/* used when si_code=SEGV_BNDERR */
 				struct {
-					char _dummy_bnd[__COMPAT_ADDR_BND_PKEY_PAD];
+					__COMPAT_SIGFAULT_LEGACY_UNION_PAD
 					compat_uptr_t _lower;
 					compat_uptr_t _upper;
 				} _addr_bnd;
 				/* used when si_code=SEGV_PKUERR */
 				struct {
-					char _dummy_pkey[__COMPAT_ADDR_BND_PKEY_PAD];
+					__COMPAT_SIGFAULT_LEGACY_UNION_PAD
 					u32 _pkey;
 				} _addr_pkey;
 				/* used when si_code=TRAP_PERF */
diff --git a/include/uapi/asm-generic/siginfo.h b/include/uapi/asm-generic/siginfo.h
index 03d6f6d2c1fe..f1c1a0300ac8 100644
--- a/include/uapi/asm-generic/siginfo.h
+++ b/include/uapi/asm-generic/siginfo.h
@@ -29,6 +29,45 @@ typedef union sigval {
 #define __ARCH_SI_ATTRIBUTES
 #endif
 
+/*
+ * The _sigfault portion of __sifields after si_addr varies depending on
+ * architecture; capture these rules here.
+ */
+struct __sifields_sigfault_addin {
+#ifdef __ARCH_SI_TRAPNO
+	int _trapno;	/* TRAP # which caused the signal */
+#endif
+	/*
+	 * used when si_code=BUS_MCEERR_AR or
+	 * used when si_code=BUS_MCEERR_AO
+	 */
+	short _addr_lsb; /* LSB of the reported address */
+
+#if defined(__ARCH_SI_TRAPNO)
+/*
+ * If we have si_trapno between si_addr and si_addr_lsb, we cannot safely move
+ * it inside the union due to alignment of si_trapno+si_addr_lsb vs. the union.
+ */
+#	define __SI_SIGFAULT_ADDIN_FIXED struct __sifields_sigfault_addin _addin;
+#	define __SI_SIGFAULT_ADDIN_UNION
+#	define __SI_SIGFAULT_LEGACY_UNION_PAD
+#else
+/*
+ * Safe to move si_addr_lsb inside the union. We will benefit from better space
+ * usage for new fields added to the union.
+ *
+ * Fields that were added after si_addr_lsb, before it become part of the union,
+ * require padding to retain the ABI. New fields do not require padding.
+ */
+#	define __SI_SIGFAULT_ADDIN_FIXED
+#	define __SI_SIGFAULT_ADDIN_UNION struct __sifields_sigfault_addin _addin;
+#	define __SI_SIGFAULT_LEGACY_UNION_PAD				\
+		char _unused[__alignof__(void *) < sizeof(short) ?	\
+					   sizeof(short) :		\
+					   __alignof__(void *)];
+#endif
+};
+
 union __sifields {
 	/* kill() */
 	struct {
@@ -63,32 +102,23 @@ union __sifields {
 	/* SIGILL, SIGFPE, SIGSEGV, SIGBUS, SIGTRAP, SIGEMT */
 	struct {
 		void __user *_addr; /* faulting insn/memory ref. */
-#ifdef __ARCH_SI_TRAPNO
-		int _trapno;	/* TRAP # which caused the signal */
-#endif
 #ifdef __ia64__
 		int _imm;		/* immediate value for "break" */
 		unsigned int _flags;	/* see ia64 si_flags */
 		unsigned long _isr;	/* isr */
 #endif
-
-#define __ADDR_BND_PKEY_PAD  (__alignof__(void *) < sizeof(short) ? \
-			      sizeof(short) : __alignof__(void *))
+		__SI_SIGFAULT_ADDIN_FIXED
 		union {
-			/*
-			 * used when si_code=BUS_MCEERR_AR or
-			 * used when si_code=BUS_MCEERR_AO
-			 */
-			short _addr_lsb; /* LSB of the reported address */
+			__SI_SIGFAULT_ADDIN_UNION
 			/* used when si_code=SEGV_BNDERR */
 			struct {
-				char _dummy_bnd[__ADDR_BND_PKEY_PAD];
+				__SI_SIGFAULT_LEGACY_UNION_PAD
 				void __user *_lower;
 				void __user *_upper;
 			} _addr_bnd;
 			/* used when si_code=SEGV_PKUERR */
 			struct {
-				char _dummy_pkey[__ADDR_BND_PKEY_PAD];
+				__SI_SIGFAULT_LEGACY_UNION_PAD
 				__u32 _pkey;
 			} _addr_pkey;
 			/* used when si_code=TRAP_PERF */
@@ -151,9 +181,9 @@ typedef struct siginfo {
 #define si_ptr		_sifields._rt._sigval.sival_ptr
 #define si_addr		_sifields._sigfault._addr
 #ifdef __ARCH_SI_TRAPNO
-#define si_trapno	_sifields._sigfault._trapno
+#define si_trapno	_sifields._sigfault._addin._trapno
 #endif
-#define si_addr_lsb	_sifields._sigfault._addr_lsb
+#define si_addr_lsb	_sifields._sigfault._addin._addr_lsb
 #define si_lower	_sifields._sigfault._addr_bnd._lower
 #define si_upper	_sifields._sigfault._addr_bnd._upper
 #define si_pkey		_sifields._sigfault._addr_pkey._pkey

Re: siginfo_t ABI break on sparc64 from si_addr_lsb move 3y ago

[Eric W. Biederman]

Marco Elver <elver@google.com> writes:

> Hello,  Eric,
>
> By inspecting the logs I've seen that about 3 years ago there had been a
> number of siginfo_t cleanups. This included moving si_addr_lsb:
>
> 	b68a68d3dcc1 ("signal: Move addr_lsb into the _sigfault union for clarity")
> 	859d880cf544 ("signal: Correct the offset of si_pkey in struct siginfo")
>  	8420f71943ae ("signal: Correct the offset of si_pkey and si_lower in struct siginfo on m68k")
>
> In an ideal world, we could just have si_addr + the union in _sigfault,
> but it seems there are more corner cases. :-/
>
> The reason I've stumbled upon this is that I wanted to add the just
> merged si_perf [1] field to glibc. But what I noticed is that glibc's
> definition and ours are vastly different around si_addr_lsb, si_lower,
> si_upper, and si_pkey.
>
> [1] https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=42dec9a936e7696bea1f27d3c5a0068cd9aa95fd
>
> In our current definition of siginfo_t, si_addr_lsb is placed into the
> same union as si_lower, si_upper, and si_pkey (and now si_perf). From
> the logs I see that si_lower, si_upper, and si_pkey are padded because
> si_addr_lsb used to be outside the union, which goes back to
> "signal: Move addr_lsb into the _sigfault union for clarity".
>
> Since then, si_addr_lsb must also be pointer-aligned, because the union
> containing it must be pointer-aligned (because si_upper, si_lower). On
> all architectures where si_addr_lsb is right after si_addr, this is
> perfectly fine, because si_addr itself is a pointer...
>
> ... except for the anomaly that are 64-bit architectures that define
> __ARCH_SI_TRAPNO and want that 'int si_trapno'. Like, for example
> sparc64, which means siginfo_t's ABI has been subtly broken on sparc64
> since v4.16.
>
> The following static asserts illustrate this:
>
> --- a/arch/sparc/kernel/signal_64.c
> +++ b/arch/sparc/kernel/signal_64.c
> @@ -556,3 +556,37 @@ void do_notify_resume(struct pt_regs *regs, unsigned long orig_i0, unsigned long
>  	user_enter();
>  }
>  
> +static_assert(offsetof(siginfo_t, si_signo)	== 0);
> +static_assert(offsetof(siginfo_t, si_errno)	== 4);
> +static_assert(offsetof(siginfo_t, si_code)	== 8);
> +static_assert(offsetof(siginfo_t, si_pid)	== 16);
> +static_assert(offsetof(siginfo_t, si_uid)	== 20);
> +static_assert(offsetof(siginfo_t, si_tid)	== 16);
> +static_assert(offsetof(siginfo_t, si_overrun)	== 20);
> +static_assert(offsetof(siginfo_t, si_status)	== 24);
> +static_assert(offsetof(siginfo_t, si_utime)	== 32);
> +static_assert(offsetof(siginfo_t, si_stime)	== 40);
> +static_assert(offsetof(siginfo_t, si_value)	== 24);
> +static_assert(offsetof(siginfo_t, si_int)	== 24);
> +static_assert(offsetof(siginfo_t, si_ptr)	== 24);
> +static_assert(offsetof(siginfo_t, si_addr)	== 16);
> +static_assert(offsetof(siginfo_t, si_trapno)	== 24);
> +#if 1 /* Correct offsets, obtained from v4.14 */
> +static_assert(offsetof(siginfo_t, si_addr_lsb)	== 28);
> +static_assert(offsetof(siginfo_t, si_lower)	== 32);
> +static_assert(offsetof(siginfo_t, si_upper)	== 40);
> +static_assert(offsetof(siginfo_t, si_pkey)	== 32);
> +#else /* Current offsets, as of v4.16 */
> +static_assert(offsetof(siginfo_t, si_addr_lsb)	== 32);
> +static_assert(offsetof(siginfo_t, si_lower)	== 40);
> +static_assert(offsetof(siginfo_t, si_upper)	== 48);
> +static_assert(offsetof(siginfo_t, si_pkey)	== 40);
> +#endif
> +static_assert(offsetof(siginfo_t, si_band)	== 16);
> +static_assert(offsetof(siginfo_t, si_fd)	== 20);
>
> ---
>
> Granted, nobody seems to have noticed because I don't even know if these
> fields have use on sparc64. But I don't yet see this as justification to
> leave things as-is...
>
> The collateral damage of this, and the acute problem that I'm having is
> defining si_perf in a sort-of readable and portable way in siginfo_t
> definitions that live outside the kernel, where sparc64 does not yet
> have broken si_addr_lsb. And the same difficulty applies to the kernel
> if we want to unbreak sparc64, while not wanting to move si_perf for
> other architectures.
>
> There are 2 options I see to solve this:
>
> 1. Make things simple again. We could just revert the change moving
>    si_addr_lsb into the union, and sadly accept we'll have to live with
>    that legacy "design" mistake. (si_perf stays in the union, but will
>    unfortunately change its offset for all architectures... this one-off
>    move might be ok because it's new.)
>
> 2. Add special cases to retain si_addr_lsb in the union on architectures
>    that do not have __ARCH_SI_TRAPNO (the majority). I have added a
>    draft patch that would do this below (with some refactoring so that
>    it remains sort-of readable), as an experiment to see how complicated
>    this gets.
>
> Which option do you prefer? Are there better options?

Personally the most important thing to have is a single definition
shared by all architectures so that we consolidate testing.

A little piece of me cries a little whenever I see how badly we
implemented the POSIX design.  As specified by POSIX the fields can be
place in siginfo such that 32bit and 64bit share a common definition.
Unfortunately we did not addpadding after si_addr on 32bit to
accommodate a 64bit si_addr.

I find it unfortunate that we are adding yet another definition that
requires translation between 32bit and 64bit, but I am glad
that at least the translation is not architecture specific.  That common
definition is what has allowed this potential issue to be caught
and that makes me very happy to see.

Let's go with Option 3.

Confirm BUS_MCEERR_AR, BUS_MCEERR_AO, SEGV_BNDERR, SEGV_PKUERR are not
in use on any architecture that defines __ARCH_SI_TRAPNO, and then fixup
the userspace definitions of these fields.

To the kernel I would add some BUILD_BUG_ON's to whatever the best
maintained architecture (sparc64?) that implements __ARCH_SI_TRAPNO just
to confirm we don't create future regressions by accident.

I did a quick search and the architectures that define __ARCH_SI_TRAPNO
are sparc, mips, and alpha.  All have 64bit implementations.  A further
quick search shows that none of those architectures have faults that
use BUS_MCEERR_AR, BUS_MCEERR_AO, SEGV_BNDERR, SEGV_PKUERR, nor do
they appear to use mm/memory-failure.c

So it doesn't look like we have an ABI regression to fix.

Eric

Re: siginfo_t ABI break on sparc64 from si_addr_lsb move 3y ago

[Marco Elver]

On Thu, 29 Apr 2021 at 19:24, Eric W. Biederman <ebiederm@xmission.com> wrote:
[...]
> > Granted, nobody seems to have noticed because I don't even know if these
> > fields have use on sparc64. But I don't yet see this as justification to
> > leave things as-is...
> >
> > The collateral damage of this, and the acute problem that I'm having is
> > defining si_perf in a sort-of readable and portable way in siginfo_t
> > definitions that live outside the kernel, where sparc64 does not yet
> > have broken si_addr_lsb. And the same difficulty applies to the kernel
> > if we want to unbreak sparc64, while not wanting to move si_perf for
> > other architectures.
> >
> > There are 2 options I see to solve this:
> >
> > 1. Make things simple again. We could just revert the change moving
> >    si_addr_lsb into the union, and sadly accept we'll have to live with
> >    that legacy "design" mistake. (si_perf stays in the union, but will
> >    unfortunately change its offset for all architectures... this one-off
> >    move might be ok because it's new.)
> >
> > 2. Add special cases to retain si_addr_lsb in the union on architectures
> >    that do not have __ARCH_SI_TRAPNO (the majority). I have added a
> >    draft patch that would do this below (with some refactoring so that
> >    it remains sort-of readable), as an experiment to see how complicated
> >    this gets.
> >
> > Which option do you prefer? Are there better options?
>
> Personally the most important thing to have is a single definition
> shared by all architectures so that we consolidate testing.
>
> A little piece of me cries a little whenever I see how badly we
> implemented the POSIX design.  As specified by POSIX the fields can be
> place in siginfo such that 32bit and 64bit share a common definition.
> Unfortunately we did not addpadding after si_addr on 32bit to
> accommodate a 64bit si_addr.

I think it's even worse than that, see the fun I had with siginfo last
week: https://lkml.kernel.org/r/20210422191823.79012-1-elver@google.com
... because of the 3 initial ints and no padding after them, we can't
portably add __u64 fields to siginfo, and are forever forced to have
subtly different behaviour between 32-bit and 64-bit architectures.
:-/

> I find it unfortunate that we are adding yet another definition that
> requires translation between 32bit and 64bit, but I am glad
> that at least the translation is not architecture specific.  That common
> definition is what has allowed this potential issue to be caught
> and that makes me very happy to see.
>
> Let's go with Option 3.
>
> Confirm BUS_MCEERR_AR, BUS_MCEERR_AO, SEGV_BNDERR, SEGV_PKUERR are not
> in use on any architecture that defines __ARCH_SI_TRAPNO, and then fixup
> the userspace definitions of these fields.
>
> To the kernel I would add some BUILD_BUG_ON's to whatever the best
> maintained architecture (sparc64?) that implements __ARCH_SI_TRAPNO just
> to confirm we don't create future regressions by accident.
>
> I did a quick search and the architectures that define __ARCH_SI_TRAPNO
> are sparc, mips, and alpha.  All have 64bit implementations.  A further
> quick search shows that none of those architectures have faults that
> use BUS_MCEERR_AR, BUS_MCEERR_AO, SEGV_BNDERR, SEGV_PKUERR, nor do
> they appear to use mm/memory-failure.c
>
> So it doesn't look like we have an ABI regression to fix.

That sounds fine to me -- my guess was that they're not used on these
architectures, but I just couldn't make that call.

I have patches adding compile-time asserts for sparc64, arm, arm64
ready to go. I'll send them after some more testing.

Thanks,
-- Marco

Re: siginfo_t ABI break on sparc64 from si_addr_lsb move 3y ago

[Arnd Bergmann]

On Thu, Apr 29, 2021 at 7:23 PM Eric W. Biederman <ebiederm@xmission.com> wrote:

> > Which option do you prefer? Are there better options?
>
> Personally the most important thing to have is a single definition
> shared by all architectures so that we consolidate testing.
>
> A little piece of me cries a little whenever I see how badly we
> implemented the POSIX design.  As specified by POSIX the fields can be
> place in siginfo such that 32bit and 64bit share a common definition.
> Unfortunately we did not addpadding after si_addr on 32bit to
> accommodate a 64bit si_addr.
>
> I find it unfortunate that we are adding yet another definition that
> requires translation between 32bit and 64bit, but I am glad
> that at least the translation is not architecture specific.  That common
> definition is what has allowed this potential issue to be caught
> and that makes me very happy to see.
>
> Let's go with Option 3.
>
> Confirm BUS_MCEERR_AR, BUS_MCEERR_AO, SEGV_BNDERR, SEGV_PKUERR are not
> in use on any architecture that defines __ARCH_SI_TRAPNO, and then fixup
> the userspace definitions of these fields.
>
> To the kernel I would add some BUILD_BUG_ON's to whatever the best
> maintained architecture (sparc64?) that implements __ARCH_SI_TRAPNO just
> to confirm we don't create future regressions by accident.
>
> I did a quick search and the architectures that define __ARCH_SI_TRAPNO
> are sparc, mips, and alpha.  All have 64bit implementations.

I think you (slightly) misread: mips has "#undef __ARCH_SI_TRAPNO", not
"#define __ARCH_SI_TRAPNO". This means it's only sparc and
alpha.

I can see that the alpha instance was added to the kernel during linux-2.5,
but never made it into the glibc or uclibc copy of the struct definition, and
musl doesn't support alpha or sparc. Debian codesearch only turns up
sparc (and BSD) references to si_trapno.

> I did a quick search and the architectures that define __ARCH_SI_TRAPNO
> are sparc, mips, and alpha.  All have 64bit implementations.  A further
> quick search shows that none of those architectures have faults that
> use BUS_MCEERR_AR, BUS_MCEERR_AO, SEGV_BNDERR, SEGV_PKUERR, nor do
> they appear to use mm/memory-failure.c
>
> So it doesn't look like we have an ABI regression to fix.

Even better!

So if sparc is the only user of _trapno and it uses none of the later
fields in _sigfault, I wonder if we could take even more liberty at
trying to have a slightly saner definition. Can you think of anything that
might break if we put _trapno inside of the union along with _perf
and _addr_lsb?

I suppose in theory sparc64 or alpha might start using the other
fields in the future, and an application might be compiled against
mismatched headers, but that is unlikely and is already broken
with the current headers.

       Arnd

Re: siginfo_t ABI break on sparc64 from si_addr_lsb move 3y ago

[Eric W. Biederman]

Arnd Bergmann <arnd@arndb.de> writes:

> On Thu, Apr 29, 2021 at 7:23 PM Eric W. Biederman <ebiederm@xmission.com> wrote:
>
>> > Which option do you prefer? Are there better options?
>>
>> Personally the most important thing to have is a single definition
>> shared by all architectures so that we consolidate testing.
>>
>> A little piece of me cries a little whenever I see how badly we
>> implemented the POSIX design.  As specified by POSIX the fields can be
>> place in siginfo such that 32bit and 64bit share a common definition.
>> Unfortunately we did not addpadding after si_addr on 32bit to
>> accommodate a 64bit si_addr.
>>
>> I find it unfortunate that we are adding yet another definition that
>> requires translation between 32bit and 64bit, but I am glad
>> that at least the translation is not architecture specific.  That common
>> definition is what has allowed this potential issue to be caught
>> and that makes me very happy to see.
>>
>> Let's go with Option 3.
>>
>> Confirm BUS_MCEERR_AR, BUS_MCEERR_AO, SEGV_BNDERR, SEGV_PKUERR are not
>> in use on any architecture that defines __ARCH_SI_TRAPNO, and then fixup
>> the userspace definitions of these fields.
>>
>> To the kernel I would add some BUILD_BUG_ON's to whatever the best
>> maintained architecture (sparc64?) that implements __ARCH_SI_TRAPNO just
>> to confirm we don't create future regressions by accident.
>>
>> I did a quick search and the architectures that define __ARCH_SI_TRAPNO
>> are sparc, mips, and alpha.  All have 64bit implementations.
>
> I think you (slightly) misread: mips has "#undef __ARCH_SI_TRAPNO", not
> "#define __ARCH_SI_TRAPNO". This means it's only sparc and
> alpha.
>
> I can see that the alpha instance was added to the kernel during linux-2.5,
> but never made it into the glibc or uclibc copy of the struct definition, and
> musl doesn't support alpha or sparc. Debian codesearch only turns up
> sparc (and BSD) references to si_trapno.



>> I did a quick search and the architectures that define __ARCH_SI_TRAPNO
>> are sparc, mips, and alpha.  All have 64bit implementations.  A further
>> quick search shows that none of those architectures have faults that
>> use BUS_MCEERR_AR, BUS_MCEERR_AO, SEGV_BNDERR, SEGV_PKUERR, nor do
>> they appear to use mm/memory-failure.c
>>
>> So it doesn't look like we have an ABI regression to fix.
>
> Even better!
>
> So if sparc is the only user of _trapno and it uses none of the later
> fields in _sigfault, I wonder if we could take even more liberty at
> trying to have a slightly saner definition. Can you think of anything that
> might break if we put _trapno inside of the union along with _perf
> and _addr_lsb?

On sparc si_trapno is only set when SIGILL ILL_TRP is set.  So we can
limit si_trapno to that combination, and it should not be a problem for
a new signal/si_code pair to use that storage.  Precisely because it is
new.

Similarly on alpha si_trapno is only set for:

SIGFPE {FPE_INTOVF, FPE_INTDIV, FPE_FLTOVF, FPE_FLTDIV, FPE_FLTUND,
FPE_FLTINV, FPE_FLTRES, FPE_FLTUNK} and SIGTRAP {TRAP_UNK}.

Placing si_trapno into the union would also make the problem that the
union is pointer aligned a non-problem as then the union immediate
follows a pointer.

I hadn't had a chance to look before but we must deal with this.  The
definition of perf_sigtrap in 42dec9a936e7696bea1f27d3c5a0068cd9aa95fd
is broken on sparc, alpha, and ia64 as it bypasses the code in
kernel/signal.c that ensures the si_trapno or the ia64 special fields
are set.

Not to mention that perf_sigtrap appears to abuse si_errno.

The code is only safe if the analysis that says we can move si_trapno
and perhaps the ia64 fields into the union is correct.  It looks like
ia64 much more actively uses it's signal extension fields including for
SIGTRAP, so I am not at all certain the generic definition of
perf_sigtrap is safe on ia64.

> I suppose in theory sparc64 or alpha might start using the other
> fields in the future, and an application might be compiled against
> mismatched headers, but that is unlikely and is already broken
> with the current headers.

If we localize the use of si_trapno to just a few special cases on alpha
and sparc I think we don't even need to worry about breaking userspace
on any architecture.  It will complicate siginfo_layout, but it is a
complication that reflects reality.

I don't have a clue how any of this affects ia64.  Does perf work on
ia64?  Does perf work on sparc, and alpha?

If perf works on ia64 we need to take a hard look at what is going on
there as well.

Eric

Re: siginfo_t ABI break on sparc64 from si_addr_lsb move 3y ago

[Marco Elver]

On Fri, Apr 30, 2021 at 12:08PM -0500, Eric W. Biederman wrote:
> Arnd Bergmann <arnd@arndb.de> writes:
[...] 
> >> I did a quick search and the architectures that define __ARCH_SI_TRAPNO
> >> are sparc, mips, and alpha.  All have 64bit implementations.  A further
> >> quick search shows that none of those architectures have faults that
> >> use BUS_MCEERR_AR, BUS_MCEERR_AO, SEGV_BNDERR, SEGV_PKUERR, nor do
> >> they appear to use mm/memory-failure.c
> >>
> >> So it doesn't look like we have an ABI regression to fix.
> >
> > Even better!
> >
> > So if sparc is the only user of _trapno and it uses none of the later
> > fields in _sigfault, I wonder if we could take even more liberty at
> > trying to have a slightly saner definition. Can you think of anything that
> > might break if we put _trapno inside of the union along with _perf
> > and _addr_lsb?
> 
> On sparc si_trapno is only set when SIGILL ILL_TRP is set.  So we can
> limit si_trapno to that combination, and it should not be a problem for
> a new signal/si_code pair to use that storage.  Precisely because it is
> new.
> 
> Similarly on alpha si_trapno is only set for:
> 
> SIGFPE {FPE_INTOVF, FPE_INTDIV, FPE_FLTOVF, FPE_FLTDIV, FPE_FLTUND,
> FPE_FLTINV, FPE_FLTRES, FPE_FLTUNK} and SIGTRAP {TRAP_UNK}.
> 
> Placing si_trapno into the union would also make the problem that the
> union is pointer aligned a non-problem as then the union immediate
> follows a pointer.
> 
> I hadn't had a chance to look before but we must deal with this.  The
> definition of perf_sigtrap in 42dec9a936e7696bea1f27d3c5a0068cd9aa95fd
> is broken on sparc, alpha, and ia64 as it bypasses the code in
> kernel/signal.c that ensures the si_trapno or the ia64 special fields
> are set.
> 
> Not to mention that perf_sigtrap appears to abuse si_errno.

There are a few other places in the kernel that repurpose si_errno
similarly, e.g. arch/arm64/kernel/ptrace.c, kernel/seccomp.c -- it was
either that or introduce another field or not have it. It is likely we
could do without, but if there are different event types the user would
have to sacrifice a few bits of si_perf to encode the event type, and
I'd rather keep those bits for something else. Thus the decision fell to
use si_errno.

Given it'd be wasted space otherwise, and we define the semantics of
whatever is stored in siginfo on the new signal, it'd be good to keep.

> The code is only safe if the analysis that says we can move si_trapno
> and perhaps the ia64 fields into the union is correct.  It looks like
> ia64 much more actively uses it's signal extension fields including for
> SIGTRAP, so I am not at all certain the generic definition of
> perf_sigtrap is safe on ia64.

Trying to understand the requirements of si_trapno myself: safe here
would mean that si_trapno is not required if we fire our SIGTRAP /
TRAP_PERF.

As far as I can tell that is the case -- see below.

> > I suppose in theory sparc64 or alpha might start using the other
> > fields in the future, and an application might be compiled against
> > mismatched headers, but that is unlikely and is already broken
> > with the current headers.
> 
> If we localize the use of si_trapno to just a few special cases on alpha
> and sparc I think we don't even need to worry about breaking userspace
> on any architecture.  It will complicate siginfo_layout, but it is a
> complication that reflects reality.
> 
> I don't have a clue how any of this affects ia64.  Does perf work on
> ia64?  Does perf work on sparc, and alpha?
> 
> If perf works on ia64 we need to take a hard look at what is going on
> there as well.

No perf on ia64, but it seems alpha and sparc have perf:

	$ git grep 'select.*HAVE_PERF_EVENTS$' -- arch/
	arch/alpha/Kconfig:	select HAVE_PERF_EVENTS    <--
	arch/arc/Kconfig:	select HAVE_PERF_EVENTS
	arch/arm/Kconfig:	select HAVE_PERF_EVENTS
	arch/arm64/Kconfig:	select HAVE_PERF_EVENTS
	arch/csky/Kconfig:	select HAVE_PERF_EVENTS
	arch/hexagon/Kconfig:	select HAVE_PERF_EVENTS
	arch/mips/Kconfig:	select HAVE_PERF_EVENTS
	arch/nds32/Kconfig:	select HAVE_PERF_EVENTS
	arch/parisc/Kconfig:	select HAVE_PERF_EVENTS
	arch/powerpc/Kconfig:	select HAVE_PERF_EVENTS
	arch/riscv/Kconfig:	select HAVE_PERF_EVENTS
	arch/s390/Kconfig:	select HAVE_PERF_EVENTS
	arch/sh/Kconfig:	select HAVE_PERF_EVENTS
	arch/sparc/Kconfig:	select HAVE_PERF_EVENTS    <--
	arch/x86/Kconfig:	select HAVE_PERF_EVENTS
	arch/xtensa/Kconfig:	select HAVE_PERF_EVENTS

Now, given ia64 is not an issue, I wanted to understand the semantics of
si_trapno. Per https://man7.org/linux/man-pages/man2/sigaction.2.html, I
see:

	int si_trapno;    /* Trap number that caused
			     hardware-generated signal
			     (unused on most architectures) */

... its intended semantics seem to suggest it would only be used by some
architecture-specific signal like you identified above. So if the
semantics is some code of a hardware trap/fault, then we're fine and do
not need to set it.

Also bearing in mind we define the semantics any new signal, and given
most architectures do not have si_trapno, definitions of new generic
signals should probably not include odd architecture specific details
related to old architectures.

From all this, my understanding now is that we can move si_trapno into
the union, correct? What else did you have in mind?

Thanks,
-- Marco

Re: siginfo_t ABI break on sparc64 from si_addr_lsb move 3y ago

[Eric W. Biederman]

Marco Elver <elver@google.com> writes:

> On Fri, Apr 30, 2021 at 12:08PM -0500, Eric W. Biederman wrote:
>> Arnd Bergmann <arnd@arndb.de> writes:
> [...] 
>> >> I did a quick search and the architectures that define __ARCH_SI_TRAPNO
>> >> are sparc, mips, and alpha.  All have 64bit implementations.  A further
>> >> quick search shows that none of those architectures have faults that
>> >> use BUS_MCEERR_AR, BUS_MCEERR_AO, SEGV_BNDERR, SEGV_PKUERR, nor do
>> >> they appear to use mm/memory-failure.c
>> >>
>> >> So it doesn't look like we have an ABI regression to fix.
>> >
>> > Even better!
>> >
>> > So if sparc is the only user of _trapno and it uses none of the later
>> > fields in _sigfault, I wonder if we could take even more liberty at
>> > trying to have a slightly saner definition. Can you think of anything that
>> > might break if we put _trapno inside of the union along with _perf
>> > and _addr_lsb?
>> 
>> On sparc si_trapno is only set when SIGILL ILL_TRP is set.  So we can
>> limit si_trapno to that combination, and it should not be a problem for
>> a new signal/si_code pair to use that storage.  Precisely because it is
>> new.
>> 
>> Similarly on alpha si_trapno is only set for:
>> 
>> SIGFPE {FPE_INTOVF, FPE_INTDIV, FPE_FLTOVF, FPE_FLTDIV, FPE_FLTUND,
>> FPE_FLTINV, FPE_FLTRES, FPE_FLTUNK} and SIGTRAP {TRAP_UNK}.
>> 
>> Placing si_trapno into the union would also make the problem that the
>> union is pointer aligned a non-problem as then the union immediate
>> follows a pointer.
>> 
>> I hadn't had a chance to look before but we must deal with this.  The
>> definition of perf_sigtrap in 42dec9a936e7696bea1f27d3c5a0068cd9aa95fd
>> is broken on sparc, alpha, and ia64 as it bypasses the code in
>> kernel/signal.c that ensures the si_trapno or the ia64 special fields
>> are set.
>> 
>> Not to mention that perf_sigtrap appears to abuse si_errno.
>
> There are a few other places in the kernel that repurpose si_errno
> similarly, e.g. arch/arm64/kernel/ptrace.c, kernel/seccomp.c -- it was
> either that or introduce another field or not have it. It is likely we
> could do without, but if there are different event types the user would
> have to sacrifice a few bits of si_perf to encode the event type, and
> I'd rather keep those bits for something else. Thus the decision fell to
> use si_errno.

arm64 only abuses si_errno in compat code for bug compatibility with
arm32.

> Given it'd be wasted space otherwise, and we define the semantics of
> whatever is stored in siginfo on the new signal, it'd be good to keep.

Except you don't completely.  You are not defining a new signal.  You
are extending the definition of SIGTRAP.  Anything generic that
responds to all SIGTRAPs can reasonably be looking at si_errno.

Further you are already adding a field with si_perf you can just as
easily add a second field with well defined semantics for that data.

>> The code is only safe if the analysis that says we can move si_trapno
>> and perhaps the ia64 fields into the union is correct.  It looks like
>> ia64 much more actively uses it's signal extension fields including for
>> SIGTRAP, so I am not at all certain the generic definition of
>> perf_sigtrap is safe on ia64.
>
> Trying to understand the requirements of si_trapno myself: safe here
> would mean that si_trapno is not required if we fire our SIGTRAP /
> TRAP_PERF.
>
> As far as I can tell that is the case -- see below.
>
>> > I suppose in theory sparc64 or alpha might start using the other
>> > fields in the future, and an application might be compiled against
>> > mismatched headers, but that is unlikely and is already broken
>> > with the current headers.
>> 
>> If we localize the use of si_trapno to just a few special cases on alpha
>> and sparc I think we don't even need to worry about breaking userspace
>> on any architecture.  It will complicate siginfo_layout, but it is a
>> complication that reflects reality.
>> 
>> I don't have a clue how any of this affects ia64.  Does perf work on
>> ia64?  Does perf work on sparc, and alpha?
>> 
>> If perf works on ia64 we need to take a hard look at what is going on
>> there as well.
>
> No perf on ia64, but it seems alpha and sparc have perf:
>
> 	$ git grep 'select.*HAVE_PERF_EVENTS$' -- arch/
> 	arch/alpha/Kconfig:	select HAVE_PERF_EVENTS    <--
> 	arch/arc/Kconfig:	select HAVE_PERF_EVENTS
> 	arch/arm/Kconfig:	select HAVE_PERF_EVENTS
> 	arch/arm64/Kconfig:	select HAVE_PERF_EVENTS
> 	arch/csky/Kconfig:	select HAVE_PERF_EVENTS
> 	arch/hexagon/Kconfig:	select HAVE_PERF_EVENTS
> 	arch/mips/Kconfig:	select HAVE_PERF_EVENTS
> 	arch/nds32/Kconfig:	select HAVE_PERF_EVENTS
> 	arch/parisc/Kconfig:	select HAVE_PERF_EVENTS
> 	arch/powerpc/Kconfig:	select HAVE_PERF_EVENTS
> 	arch/riscv/Kconfig:	select HAVE_PERF_EVENTS
> 	arch/s390/Kconfig:	select HAVE_PERF_EVENTS
> 	arch/sh/Kconfig:	select HAVE_PERF_EVENTS
> 	arch/sparc/Kconfig:	select HAVE_PERF_EVENTS    <--
> 	arch/x86/Kconfig:	select HAVE_PERF_EVENTS
> 	arch/xtensa/Kconfig:	select HAVE_PERF_EVENTS
>
> Now, given ia64 is not an issue, I wanted to understand the semantics of
> si_trapno. Per https://man7.org/linux/man-pages/man2/sigaction.2.html, I
> see:
>
> 	int si_trapno;    /* Trap number that caused
> 			     hardware-generated signal
> 			     (unused on most architectures) */
>
> ... its intended semantics seem to suggest it would only be used by some
> architecture-specific signal like you identified above. So if the
> semantics is some code of a hardware trap/fault, then we're fine and do
> not need to set it.
>
> Also bearing in mind we define the semantics any new signal, and given
> most architectures do not have si_trapno, definitions of new generic
> signals should probably not include odd architecture specific details
> related to old architectures.
>
> From all this, my understanding now is that we can move si_trapno into
> the union, correct? What else did you have in mind?

Yes.  Let's move si_trapno into the union.

That implies a few things like siginfo_layout needs to change.

The helpers in kernel/signal.c can change to not imply that
if you define __ARCH_SI_TRAPNO you must always define and
pass in si_trapno.  A force_sig_trapno could be defined instead
to handle the cases that alpha and sparc use si_trapno.

It would be nice if a force_sig_perf_trap could be factored
out of perf_trap and placed in kernel/signal.c.

My experience (especially this round) is that it becomes much easier to
audit the users of siginfo if there is a dedicated function in
kernel/signal.c that is simply passed the parameters that need
to be placed in siginfo.

So I would very much like to see if I can make force_sig_info static.

Eric

Re: siginfo_t ABI break on sparc64 from si_addr_lsb move 3y ago

[Marco Elver]

On Fri, 30 Apr 2021 at 22:15, Eric W. Biederman <ebiederm@xmission.com> wrote:
[...]
> arm64 only abuses si_errno in compat code for bug compatibility with
> arm32.
>
> > Given it'd be wasted space otherwise, and we define the semantics of
> > whatever is stored in siginfo on the new signal, it'd be good to keep.
>
> Except you don't completely.  You are not defining a new signal.  You
> are extending the definition of SIGTRAP.  Anything generic that
> responds to all SIGTRAPs can reasonably be looking at si_errno.

I see where you're coming from, and agree with this if si_errno
already had some semantics for some subset of SIGTRAPs. I've tried to
analyze the situation a bit further, since siginfo seems to be a giant
minefield and semantics is underspecified at best. :-)

Do any of the existing SIGTRAPs define si_errno to be set? As far as I
can tell, they don't.

If this is true, I think there are benefits and downsides to
repurposing si_errno (similar to what SIGSYS did). The obvious
downside is as you suggest, it's not always a real errno. The benefit
is that we avoid introducing more and more fields -- i.e. if we permit
si_errno to be repurposed for SIGTRAP and its value depends on the
precise si_code, too, we simplify siginfo's overall definition (also
given every new field needs more code in kernel/signal.c, too).

Given SIGTRAPs are in response to some user-selected event in the
user's code (breakpoints, ptrace, etc. ... now perf events), the user
must already check the si_code to select the right action because
SIGTRAPs are not alike (unlike, e.g. SIGSEGV). Because of this, I
think that repurposing si_errno in an si_code-dependent way for
SIGTRAPs is safe.

If you think it is simply untenable to repurpose si_errno for
SIGTRAPs, please confirm -- I'll just send a minimal patch to fix (I'd
probably just remove setting it... everything else is too intrusive as
a "fix".. sigh).

The cleanups as you outline below seem orthogonal and not urgent for
5.13 (all changes and cleanups for __ARCH_SI_TRAPNO seem too intrusive
without -next exposure).

Thanks,
-- Marco

> Further you are already adding a field with si_perf you can just as
> easily add a second field with well defined semantics for that data.
>
> >> The code is only safe if the analysis that says we can move si_trapno
> >> and perhaps the ia64 fields into the union is correct.  It looks like
> >> ia64 much more actively uses it's signal extension fields including for
> >> SIGTRAP, so I am not at all certain the generic definition of
> >> perf_sigtrap is safe on ia64.
> >
> > Trying to understand the requirements of si_trapno myself: safe here
> > would mean that si_trapno is not required if we fire our SIGTRAP /
> > TRAP_PERF.
> >
> > As far as I can tell that is the case -- see below.
> >
> >> > I suppose in theory sparc64 or alpha might start using the other
> >> > fields in the future, and an application might be compiled against
> >> > mismatched headers, but that is unlikely and is already broken
> >> > with the current headers.
> >>
> >> If we localize the use of si_trapno to just a few special cases on alpha
> >> and sparc I think we don't even need to worry about breaking userspace
> >> on any architecture.  It will complicate siginfo_layout, but it is a
> >> complication that reflects reality.
> >>
> >> I don't have a clue how any of this affects ia64.  Does perf work on
> >> ia64?  Does perf work on sparc, and alpha?
> >>
> >> If perf works on ia64 we need to take a hard look at what is going on
> >> there as well.
> >
> > No perf on ia64, but it seems alpha and sparc have perf:
> >
> >       $ git grep 'select.*HAVE_PERF_EVENTS$' -- arch/
> >       arch/alpha/Kconfig:     select HAVE_PERF_EVENTS    <--
> >       arch/arc/Kconfig:       select HAVE_PERF_EVENTS
> >       arch/arm/Kconfig:       select HAVE_PERF_EVENTS
> >       arch/arm64/Kconfig:     select HAVE_PERF_EVENTS
> >       arch/csky/Kconfig:      select HAVE_PERF_EVENTS
> >       arch/hexagon/Kconfig:   select HAVE_PERF_EVENTS
> >       arch/mips/Kconfig:      select HAVE_PERF_EVENTS
> >       arch/nds32/Kconfig:     select HAVE_PERF_EVENTS
> >       arch/parisc/Kconfig:    select HAVE_PERF_EVENTS
> >       arch/powerpc/Kconfig:   select HAVE_PERF_EVENTS
> >       arch/riscv/Kconfig:     select HAVE_PERF_EVENTS
> >       arch/s390/Kconfig:      select HAVE_PERF_EVENTS
> >       arch/sh/Kconfig:        select HAVE_PERF_EVENTS
> >       arch/sparc/Kconfig:     select HAVE_PERF_EVENTS    <--
> >       arch/x86/Kconfig:       select HAVE_PERF_EVENTS
> >       arch/xtensa/Kconfig:    select HAVE_PERF_EVENTS
> >
> > Now, given ia64 is not an issue, I wanted to understand the semantics of
> > si_trapno. Per https://man7.org/linux/man-pages/man2/sigaction.2.html, I
> > see:
> >
> >       int si_trapno;    /* Trap number that caused
> >                            hardware-generated signal
> >                            (unused on most architectures) */
> >
> > ... its intended semantics seem to suggest it would only be used by some
> > architecture-specific signal like you identified above. So if the
> > semantics is some code of a hardware trap/fault, then we're fine and do
> > not need to set it.
> >
> > Also bearing in mind we define the semantics any new signal, and given
> > most architectures do not have si_trapno, definitions of new generic
> > signals should probably not include odd architecture specific details
> > related to old architectures.
> >
> > From all this, my understanding now is that we can move si_trapno into
> > the union, correct? What else did you have in mind?
>
> Yes.  Let's move si_trapno into the union.
>
> That implies a few things like siginfo_layout needs to change.
>
> The helpers in kernel/signal.c can change to not imply that
> if you define __ARCH_SI_TRAPNO you must always define and
> pass in si_trapno.  A force_sig_trapno could be defined instead
> to handle the cases that alpha and sparc use si_trapno.
>
> It would be nice if a force_sig_perf_trap could be factored
> out of perf_trap and placed in kernel/signal.c.
>
> My experience (especially this round) is that it becomes much easier to
> audit the users of siginfo if there is a dedicated function in
> kernel/signal.c that is simply passed the parameters that need
> to be placed in siginfo.
>
> So I would very much like to see if I can make force_sig_info static.
>
> Eric
>

[RFC][PATCH 0/3] signal: Move si_trapno into the _si_fault union

[Eric W. Biederman]

Eric W. Biederman (3):
      siginfo: Move si_trapno inside the union inside _si_fault
      signal: Implement SIL_FAULT_TRAPNO
      signal: Use dedicated helpers to send signals with si_trapno set

 arch/alpha/kernel/osf_sys.c        |  2 +-
 arch/alpha/kernel/signal.c         |  4 +-
 arch/alpha/kernel/traps.c          | 24 ++++++------
 arch/alpha/mm/fault.c              |  4 +-
 arch/sparc/kernel/process_64.c     |  2 +-
 arch/sparc/kernel/sys_sparc_32.c   |  2 +-
 arch/sparc/kernel/sys_sparc_64.c   |  2 +-
 arch/sparc/kernel/traps_32.c       | 22 +++++------
 arch/sparc/kernel/traps_64.c       | 44 ++++++++++------------
 arch/sparc/kernel/unaligned_32.c   |  2 +-
 arch/sparc/mm/fault_32.c           |  2 +-
 arch/sparc/mm/fault_64.c           |  2 +-
 fs/signalfd.c                      |  7 +---
 include/linux/compat.h             |  4 +-
 include/linux/sched/signal.h       | 12 ++----
 include/linux/signal.h             |  1 +
 include/uapi/asm-generic/siginfo.h |  6 +--
 kernel/signal.c                    | 77 ++++++++++++++++++++++----------------
 18 files changed, 107 insertions(+), 112 deletions(-)

[PATCH 1/3] siginfo: Move si_trapno inside the union inside _si_fault

[Eric W. Biederman]

It turns out that linux uses si_trapno very sparingly, and as such it
can be considered extra information for a very narrow selection of
signals, rather than information that is present with every fault
reported in siginfo.

As such move si_trapno inside the union inside of _si_fault.  This
results in no change in placement, and makes it eaiser to extend
_si_fault in the future as this reduces the number of special cases.
In particular with si_trapno included in the union it is no longer a
concern that the union must be pointer alligned on most architectures
because the union followes immediately after si_addr which is a
pointer.

Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
---
 include/linux/compat.h             | 4 +---
 include/uapi/asm-generic/siginfo.h | 6 +-----
 2 files changed, 2 insertions(+), 8 deletions(-)

diff --git a/include/linux/compat.h b/include/linux/compat.h
index f0d2dd35d408..24462ed63af4 100644
--- a/include/linux/compat.h
+++ b/include/linux/compat.h
@@ -214,12 +214,10 @@ typedef struct compat_siginfo {
 		/* SIGILL, SIGFPE, SIGSEGV, SIGBUS, SIGTRAP, SIGEMT */
 		struct {
 			compat_uptr_t _addr;	/* faulting insn/memory ref. */
-#ifdef __ARCH_SI_TRAPNO
-			int _trapno;	/* TRAP # which caused the signal */
-#endif
 #define __COMPAT_ADDR_BND_PKEY_PAD  (__alignof__(compat_uptr_t) < sizeof(short) ? \
 				     sizeof(short) : __alignof__(compat_uptr_t))
 			union {
+				int _trapno;	/* TRAP # which caused the signal */
 				/*
 				 * used when si_code=BUS_MCEERR_AR or
 				 * used when si_code=BUS_MCEERR_AO
diff --git a/include/uapi/asm-generic/siginfo.h b/include/uapi/asm-generic/siginfo.h
index 03d6f6d2c1fe..2abdf1d19aad 100644
--- a/include/uapi/asm-generic/siginfo.h
+++ b/include/uapi/asm-generic/siginfo.h
@@ -63,9 +63,6 @@ union __sifields {
 	/* SIGILL, SIGFPE, SIGSEGV, SIGBUS, SIGTRAP, SIGEMT */
 	struct {
 		void __user *_addr; /* faulting insn/memory ref. */
-#ifdef __ARCH_SI_TRAPNO
-		int _trapno;	/* TRAP # which caused the signal */
-#endif
 #ifdef __ia64__
 		int _imm;		/* immediate value for "break" */
 		unsigned int _flags;	/* see ia64 si_flags */
@@ -75,6 +72,7 @@ union __sifields {
 #define __ADDR_BND_PKEY_PAD  (__alignof__(void *) < sizeof(short) ? \
 			      sizeof(short) : __alignof__(void *))
 		union {
+			int _trapno;	/* TRAP # which caused the signal */
 			/*
 			 * used when si_code=BUS_MCEERR_AR or
 			 * used when si_code=BUS_MCEERR_AO
@@ -150,9 +148,7 @@ typedef struct siginfo {
 #define si_int		_sifields._rt._sigval.sival_int
 #define si_ptr		_sifields._rt._sigval.sival_ptr
 #define si_addr		_sifields._sigfault._addr
-#ifdef __ARCH_SI_TRAPNO
 #define si_trapno	_sifields._sigfault._trapno
-#endif
 #define si_addr_lsb	_sifields._sigfault._addr_lsb
 #define si_lower	_sifields._sigfault._addr_bnd._lower
 #define si_upper	_sifields._sigfault._addr_bnd._upper
-- 
2.30.1

Re: [PATCH 1/3] siginfo: Move si_trapno inside the union inside _si_fault

[Marco Elver]

On Sat, 1 May 2021 at 00:50, Eric W. Biederman <ebiederm@xmission.com> wrote:
>
> It turns out that linux uses si_trapno very sparingly, and as such it
> can be considered extra information for a very narrow selection of
> signals, rather than information that is present with every fault
> reported in siginfo.
>
> As such move si_trapno inside the union inside of _si_fault.  This
> results in no change in placement, and makes it eaiser to extend
> _si_fault in the future as this reduces the number of special cases.
> In particular with si_trapno included in the union it is no longer a
> concern that the union must be pointer alligned on most architectures
> because the union followes immediately after si_addr which is a
> pointer.
>

Maybe add "Link:
https://lkml.kernel.org/r/CAK8P3a0+uKYwL1NhY6Hvtieghba2hKYGD6hcKx5n8=4Gtt+pHA@mail.gmail.com"

> Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>

Acked-by: Marco Elver <elver@google.com>

By no longer guarding it with __ARCH_SI_TRAPNO we run the risk that it
will be used by something else at some point. Is that intentional?

Thanks,
-- Marco

> ---
>  include/linux/compat.h             | 4 +---
>  include/uapi/asm-generic/siginfo.h | 6 +-----
>  2 files changed, 2 insertions(+), 8 deletions(-)
>
> diff --git a/include/linux/compat.h b/include/linux/compat.h
> index f0d2dd35d408..24462ed63af4 100644
> --- a/include/linux/compat.h
> +++ b/include/linux/compat.h
> @@ -214,12 +214,10 @@ typedef struct compat_siginfo {
>                 /* SIGILL, SIGFPE, SIGSEGV, SIGBUS, SIGTRAP, SIGEMT */
>                 struct {
>                         compat_uptr_t _addr;    /* faulting insn/memory ref. */
> -#ifdef __ARCH_SI_TRAPNO
> -                       int _trapno;    /* TRAP # which caused the signal */
> -#endif
>  #define __COMPAT_ADDR_BND_PKEY_PAD  (__alignof__(compat_uptr_t) < sizeof(short) ? \
>                                      sizeof(short) : __alignof__(compat_uptr_t))
>                         union {
> +                               int _trapno;    /* TRAP # which caused the signal */
>                                 /*
>                                  * used when si_code=BUS_MCEERR_AR or
>                                  * used when si_code=BUS_MCEERR_AO
> diff --git a/include/uapi/asm-generic/siginfo.h b/include/uapi/asm-generic/siginfo.h
> index 03d6f6d2c1fe..2abdf1d19aad 100644
> --- a/include/uapi/asm-generic/siginfo.h
> +++ b/include/uapi/asm-generic/siginfo.h
> @@ -63,9 +63,6 @@ union __sifields {
>         /* SIGILL, SIGFPE, SIGSEGV, SIGBUS, SIGTRAP, SIGEMT */
>         struct {
>                 void __user *_addr; /* faulting insn/memory ref. */
> -#ifdef __ARCH_SI_TRAPNO
> -               int _trapno;    /* TRAP # which caused the signal */
> -#endif
>  #ifdef __ia64__
>                 int _imm;               /* immediate value for "break" */
>                 unsigned int _flags;    /* see ia64 si_flags */
> @@ -75,6 +72,7 @@ union __sifields {
>  #define __ADDR_BND_PKEY_PAD  (__alignof__(void *) < sizeof(short) ? \
>                               sizeof(short) : __alignof__(void *))
>                 union {
> +                       int _trapno;    /* TRAP # which caused the signal */
>                         /*
>                          * used when si_code=BUS_MCEERR_AR or
>                          * used when si_code=BUS_MCEERR_AO
> @@ -150,9 +148,7 @@ typedef struct siginfo {
>  #define si_int         _sifields._rt._sigval.sival_int
>  #define si_ptr         _sifields._rt._sigval.sival_ptr
>  #define si_addr                _sifields._sigfault._addr
> -#ifdef __ARCH_SI_TRAPNO
>  #define si_trapno      _sifields._sigfault._trapno
> -#endif
>  #define si_addr_lsb    _sifields._sigfault._addr_lsb
>  #define si_lower       _sifields._sigfault._addr_bnd._lower
>  #define si_upper       _sifields._sigfault._addr_bnd._upper
> --
> 2.30.1

Re: [PATCH 1/3] siginfo: Move si_trapno inside the union inside _si_fault

[Eric W. Biederman]

Marco Elver <elver@google.com> writes:

> On Sat, 1 May 2021 at 00:50, Eric W. Biederman <ebiederm@xmission.com> wrote:
>>
>> It turns out that linux uses si_trapno very sparingly, and as such it
>> can be considered extra information for a very narrow selection of
>> signals, rather than information that is present with every fault
>> reported in siginfo.
>>
>> As such move si_trapno inside the union inside of _si_fault.  This
>> results in no change in placement, and makes it eaiser to extend
>> _si_fault in the future as this reduces the number of special cases.
>> In particular with si_trapno included in the union it is no longer a
>> concern that the union must be pointer alligned on most architectures
>> because the union followes immediately after si_addr which is a
>> pointer.
>>
>
> Maybe add "Link:
> https://lkml.kernel.org/r/CAK8P3a0+uKYwL1NhY6Hvtieghba2hKYGD6hcKx5n8=4Gtt+pHA@mail.gmail.com"
>
>> Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
>
> Acked-by: Marco Elver <elver@google.com>
>
> By no longer guarding it with __ARCH_SI_TRAPNO we run the risk that it
> will be used by something else at some point. Is that intentional?

The motivation was letting the code be tested on other architectures.

But once si_trapno falls inside the union instead of being present for
every signal reporting a fault it doesn't really matter.

I think it would be poor taste but harmless to use si_trapno, mostly
because defining a new entry in the union could be more specific and
well defined.

Eric

[PATCH 2/3] signal: Implement SIL_FAULT_TRAPNO

[Eric W. Biederman]

Now that si_trapno is part of the union in _si_fault and available on
all architectures, add SIL_FAULT_TRAPNO and update siginfo_layout to
return SIL_FAULT_TRAPNO when si_trapno is actually used.

Update the code that uses siginfo_layout to deal with SIL_FAULT_TRAPNO
and have the same code ignore si_trapno in in all other cases.

Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
---
 fs/signalfd.c          |  7 ++-----
 include/linux/signal.h |  1 +
 kernel/signal.c        | 36 ++++++++++++++----------------------
 3 files changed, 17 insertions(+), 27 deletions(-)

diff --git a/fs/signalfd.c b/fs/signalfd.c
index 040a1142915f..126c681a30e7 100644
--- a/fs/signalfd.c
+++ b/fs/signalfd.c
@@ -123,15 +123,12 @@ static int signalfd_copyinfo(struct signalfd_siginfo __user *uinfo,
 		 */
 	case SIL_FAULT:
 		new.ssi_addr = (long) kinfo->si_addr;
-#ifdef __ARCH_SI_TRAPNO
+	case SIL_FAULT_TRAPNO:
+		new.ssi_addr = (long) kinfo->si_addr;
 		new.ssi_trapno = kinfo->si_trapno;
-#endif
 		break;
 	case SIL_FAULT_MCEERR:
 		new.ssi_addr = (long) kinfo->si_addr;
-#ifdef __ARCH_SI_TRAPNO
-		new.ssi_trapno = kinfo->si_trapno;
-#endif
 		new.ssi_addr_lsb = (short) kinfo->si_addr_lsb;
 		break;
 	case SIL_PERF_EVENT:
diff --git a/include/linux/signal.h b/include/linux/signal.h
index 1e98548d7cf6..5160fd45e5ca 100644
--- a/include/linux/signal.h
+++ b/include/linux/signal.h
@@ -40,6 +40,7 @@ enum siginfo_layout {
 	SIL_TIMER,
 	SIL_POLL,
 	SIL_FAULT,
+	SIL_FAULT_TRAPNO,
 	SIL_FAULT_MCEERR,
 	SIL_FAULT_BNDERR,
 	SIL_FAULT_PKUERR,
diff --git a/kernel/signal.c b/kernel/signal.c
index c3017aa8024a..7b2d61cb7411 100644
--- a/kernel/signal.c
+++ b/kernel/signal.c
@@ -1194,6 +1194,7 @@ static inline bool has_si_pid_and_uid(struct kernel_siginfo *info)
 	case SIL_TIMER:
 	case SIL_POLL:
 	case SIL_FAULT:
+	case SIL_FAULT_TRAPNO:
 	case SIL_FAULT_MCEERR:
 	case SIL_FAULT_BNDERR:
 	case SIL_FAULT_PKUERR:
@@ -2527,6 +2528,7 @@ static void hide_si_addr_tag_bits(struct ksignal *ksig)
 {
 	switch (siginfo_layout(ksig->sig, ksig->info.si_code)) {
 	case SIL_FAULT:
+	case SIL_FAULT_TRAPNO:
 	case SIL_FAULT_MCEERR:
 	case SIL_FAULT_BNDERR:
 	case SIL_FAULT_PKUERR:
@@ -3206,6 +3208,12 @@ enum siginfo_layout siginfo_layout(unsigned sig, int si_code)
 			if ((sig == SIGBUS) &&
 			    (si_code >= BUS_MCEERR_AR) && (si_code <= BUS_MCEERR_AO))
 				layout = SIL_FAULT_MCEERR;
+			else if (IS_ENABLED(ALPHA) &&
+				 ((sig == SIGFPE) ||
+				  ((sig == SIGTRAP) && (si_code == TRAP_UNK))))
+				layout = SIL_FAULT_TRAPNO;
+			else if (IS_ENABLED(SPARC) && (sig == SIGILL) && (si_code == ILL_ILLTRP))
+				layout = SIL_FAULT_TRAPNO;
 			else if ((sig == SIGSEGV) && (si_code == SEGV_BNDERR))
 				layout = SIL_FAULT_BNDERR;
 #ifdef SEGV_PKUERR
@@ -3317,30 +3325,22 @@ void copy_siginfo_to_external32(struct compat_siginfo *to,
 		break;
 	case SIL_FAULT:
 		to->si_addr = ptr_to_compat(from->si_addr);
-#ifdef __ARCH_SI_TRAPNO
+		break;
+	case SIL_FAULT_TRAPNO:
+		to->si_addr = ptr_to_compat(from->si_addr);
 		to->si_trapno = from->si_trapno;
-#endif
 		break;
 	case SIL_FAULT_MCEERR:
 		to->si_addr = ptr_to_compat(from->si_addr);
-#ifdef __ARCH_SI_TRAPNO
-		to->si_trapno = from->si_trapno;
-#endif
 		to->si_addr_lsb = from->si_addr_lsb;
 		break;
 	case SIL_FAULT_BNDERR:
 		to->si_addr = ptr_to_compat(from->si_addr);
-#ifdef __ARCH_SI_TRAPNO
-		to->si_trapno = from->si_trapno;
-#endif
 		to->si_lower = ptr_to_compat(from->si_lower);
 		to->si_upper = ptr_to_compat(from->si_upper);
 		break;
 	case SIL_FAULT_PKUERR:
 		to->si_addr = ptr_to_compat(from->si_addr);
-#ifdef __ARCH_SI_TRAPNO
-		to->si_trapno = from->si_trapno;
-#endif
 		to->si_pkey = from->si_pkey;
 		break;
 	case SIL_PERF_EVENT:
@@ -3401,30 +3401,22 @@ static int post_copy_siginfo_from_user32(kernel_siginfo_t *to,
 		break;
 	case SIL_FAULT:
 		to->si_addr = compat_ptr(from->si_addr);
-#ifdef __ARCH_SI_TRAPNO
+		break;
+	case SIL_FAULT_TRAPNO:
+		to->si_addr = compat_ptr(from->si_addr);
 		to->si_trapno = from->si_trapno;
-#endif
 		break;
 	case SIL_FAULT_MCEERR:
 		to->si_addr = compat_ptr(from->si_addr);
-#ifdef __ARCH_SI_TRAPNO
-		to->si_trapno = from->si_trapno;
-#endif
 		to->si_addr_lsb = from->si_addr_lsb;
 		break;
 	case SIL_FAULT_BNDERR:
 		to->si_addr = compat_ptr(from->si_addr);
-#ifdef __ARCH_SI_TRAPNO
-		to->si_trapno = from->si_trapno;
-#endif
 		to->si_lower = compat_ptr(from->si_lower);
 		to->si_upper = compat_ptr(from->si_upper);
 		break;
 	case SIL_FAULT_PKUERR:
 		to->si_addr = compat_ptr(from->si_addr);
-#ifdef __ARCH_SI_TRAPNO
-		to->si_trapno = from->si_trapno;
-#endif
 		to->si_pkey = from->si_pkey;
 		break;
 	case SIL_PERF_EVENT:
-- 
2.30.1

Re: [PATCH 2/3] signal: Implement SIL_FAULT_TRAPNO

[Eric W. Biederman]

ebiederm@xmission.com (Eric W. Biederman) writes:

> Now that si_trapno is part of the union in _si_fault and available on
> all architectures, add SIL_FAULT_TRAPNO and update siginfo_layout to
> return SIL_FAULT_TRAPNO when si_trapno is actually used.
>
> Update the code that uses siginfo_layout to deal with SIL_FAULT_TRAPNO
> and have the same code ignore si_trapno in in all other cases.

This change is missing a break in signalfd.

Eric

> Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
> ---
>  fs/signalfd.c          |  7 ++-----
>  include/linux/signal.h |  1 +
>  kernel/signal.c        | 36 ++++++++++++++----------------------
>  3 files changed, 17 insertions(+), 27 deletions(-)
>
> diff --git a/fs/signalfd.c b/fs/signalfd.c
> index 040a1142915f..126c681a30e7 100644
> --- a/fs/signalfd.c
> +++ b/fs/signalfd.c
> @@ -123,15 +123,12 @@ static int signalfd_copyinfo(struct signalfd_siginfo __user *uinfo,
>  		 */
>  	case SIL_FAULT:
>  		new.ssi_addr = (long) kinfo->si_addr;
+ 		break;
> -#ifdef __ARCH_SI_TRAPNO
> +	case SIL_FAULT_TRAPNO:
> +		new.ssi_addr = (long) kinfo->si_addr;
>  		new.ssi_trapno = kinfo->si_trapno;
> -#endif
>  		break;
>  	case SIL_FAULT_MCEERR:
>  		new.ssi_addr = (long) kinfo->si_addr;
> -#ifdef __ARCH_SI_TRAPNO
> -		new.ssi_trapno = kinfo->si_trapno;
> -#endif
>  		new.ssi_addr_lsb = (short) kinfo->si_addr_lsb;
>  		break;
>  	case SIL_PERF_EVENT:
> diff --git a/include/linux/signal.h b/include/linux/signal.h
> index 1e98548d7cf6..5160fd45e5ca 100644
> --- a/include/linux/signal.h
> +++ b/include/linux/signal.h
> @@ -40,6 +40,7 @@ enum siginfo_layout {
>  	SIL_TIMER,
>  	SIL_POLL,
>  	SIL_FAULT,
> +	SIL_FAULT_TRAPNO,
>  	SIL_FAULT_MCEERR,
>  	SIL_FAULT_BNDERR,
>  	SIL_FAULT_PKUERR,
> diff --git a/kernel/signal.c b/kernel/signal.c
> index c3017aa8024a..7b2d61cb7411 100644
> --- a/kernel/signal.c
> +++ b/kernel/signal.c
> @@ -1194,6 +1194,7 @@ static inline bool has_si_pid_and_uid(struct kernel_siginfo *info)
>  	case SIL_TIMER:
>  	case SIL_POLL:
>  	case SIL_FAULT:
> +	case SIL_FAULT_TRAPNO:
>  	case SIL_FAULT_MCEERR:
>  	case SIL_FAULT_BNDERR:
>  	case SIL_FAULT_PKUERR:
> @@ -2527,6 +2528,7 @@ static void hide_si_addr_tag_bits(struct ksignal *ksig)
>  {
>  	switch (siginfo_layout(ksig->sig, ksig->info.si_code)) {
>  	case SIL_FAULT:
> +	case SIL_FAULT_TRAPNO:
>  	case SIL_FAULT_MCEERR:
>  	case SIL_FAULT_BNDERR:
>  	case SIL_FAULT_PKUERR:
> @@ -3206,6 +3208,12 @@ enum siginfo_layout siginfo_layout(unsigned sig, int si_code)
>  			if ((sig == SIGBUS) &&
>  			    (si_code >= BUS_MCEERR_AR) && (si_code <= BUS_MCEERR_AO))
>  				layout = SIL_FAULT_MCEERR;
> +			else if (IS_ENABLED(ALPHA) &&
> +				 ((sig == SIGFPE) ||
> +				  ((sig == SIGTRAP) && (si_code == TRAP_UNK))))
> +				layout = SIL_FAULT_TRAPNO;
> +			else if (IS_ENABLED(SPARC) && (sig == SIGILL) && (si_code == ILL_ILLTRP))
> +				layout = SIL_FAULT_TRAPNO;
>  			else if ((sig == SIGSEGV) && (si_code == SEGV_BNDERR))
>  				layout = SIL_FAULT_BNDERR;
>  #ifdef SEGV_PKUERR
> @@ -3317,30 +3325,22 @@ void copy_siginfo_to_external32(struct compat_siginfo *to,
>  		break;
>  	case SIL_FAULT:
>  		to->si_addr = ptr_to_compat(from->si_addr);
> -#ifdef __ARCH_SI_TRAPNO
> +		break;
> +	case SIL_FAULT_TRAPNO:
> +		to->si_addr = ptr_to_compat(from->si_addr);
>  		to->si_trapno = from->si_trapno;
> -#endif
>  		break;
>  	case SIL_FAULT_MCEERR:
>  		to->si_addr = ptr_to_compat(from->si_addr);
> -#ifdef __ARCH_SI_TRAPNO
> -		to->si_trapno = from->si_trapno;
> -#endif
>  		to->si_addr_lsb = from->si_addr_lsb;
>  		break;
>  	case SIL_FAULT_BNDERR:
>  		to->si_addr = ptr_to_compat(from->si_addr);
> -#ifdef __ARCH_SI_TRAPNO
> -		to->si_trapno = from->si_trapno;
> -#endif
>  		to->si_lower = ptr_to_compat(from->si_lower);
>  		to->si_upper = ptr_to_compat(from->si_upper);
>  		break;
>  	case SIL_FAULT_PKUERR:
>  		to->si_addr = ptr_to_compat(from->si_addr);
> -#ifdef __ARCH_SI_TRAPNO
> -		to->si_trapno = from->si_trapno;
> -#endif
>  		to->si_pkey = from->si_pkey;
>  		break;
>  	case SIL_PERF_EVENT:
> @@ -3401,30 +3401,22 @@ static int post_copy_siginfo_from_user32(kernel_siginfo_t *to,
>  		break;
>  	case SIL_FAULT:
>  		to->si_addr = compat_ptr(from->si_addr);
> -#ifdef __ARCH_SI_TRAPNO
> +		break;
> +	case SIL_FAULT_TRAPNO:
> +		to->si_addr = compat_ptr(from->si_addr);
>  		to->si_trapno = from->si_trapno;
> -#endif
>  		break;
>  	case SIL_FAULT_MCEERR:
>  		to->si_addr = compat_ptr(from->si_addr);
> -#ifdef __ARCH_SI_TRAPNO
> -		to->si_trapno = from->si_trapno;
> -#endif
>  		to->si_addr_lsb = from->si_addr_lsb;
>  		break;
>  	case SIL_FAULT_BNDERR:
>  		to->si_addr = compat_ptr(from->si_addr);
> -#ifdef __ARCH_SI_TRAPNO
> -		to->si_trapno = from->si_trapno;
> -#endif
>  		to->si_lower = compat_ptr(from->si_lower);
>  		to->si_upper = compat_ptr(from->si_upper);
>  		break;
>  	case SIL_FAULT_PKUERR:
>  		to->si_addr = compat_ptr(from->si_addr);
> -#ifdef __ARCH_SI_TRAPNO
> -		to->si_trapno = from->si_trapno;
> -#endif
>  		to->si_pkey = from->si_pkey;
>  		break;
>  	case SIL_PERF_EVENT:

Re: [PATCH 2/3] signal: Implement SIL_FAULT_TRAPNO

[Marco Elver]

On Sat, 1 May 2021 at 00:54, Eric W. Biederman <ebiederm@xmission.com> wrote:
>
> Now that si_trapno is part of the union in _si_fault and available on
> all architectures, add SIL_FAULT_TRAPNO and update siginfo_layout to
> return SIL_FAULT_TRAPNO when si_trapno is actually used.
>
> Update the code that uses siginfo_layout to deal with SIL_FAULT_TRAPNO
> and have the same code ignore si_trapno in in all other cases.
>
> Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
> ---
>  fs/signalfd.c          |  7 ++-----
>  include/linux/signal.h |  1 +
>  kernel/signal.c        | 36 ++++++++++++++----------------------
>  3 files changed, 17 insertions(+), 27 deletions(-)
>
> diff --git a/fs/signalfd.c b/fs/signalfd.c
> index 040a1142915f..126c681a30e7 100644
> --- a/fs/signalfd.c
> +++ b/fs/signalfd.c
> @@ -123,15 +123,12 @@ static int signalfd_copyinfo(struct signalfd_siginfo __user *uinfo,
>                  */
>         case SIL_FAULT:
>                 new.ssi_addr = (long) kinfo->si_addr;
> -#ifdef __ARCH_SI_TRAPNO
> +       case SIL_FAULT_TRAPNO:
> +               new.ssi_addr = (long) kinfo->si_addr;
>                 new.ssi_trapno = kinfo->si_trapno;
> -#endif
>                 break;
>         case SIL_FAULT_MCEERR:
>                 new.ssi_addr = (long) kinfo->si_addr;
> -#ifdef __ARCH_SI_TRAPNO
> -               new.ssi_trapno = kinfo->si_trapno;
> -#endif
>                 new.ssi_addr_lsb = (short) kinfo->si_addr_lsb;
>                 break;
>         case SIL_PERF_EVENT:
> diff --git a/include/linux/signal.h b/include/linux/signal.h
> index 1e98548d7cf6..5160fd45e5ca 100644
> --- a/include/linux/signal.h
> +++ b/include/linux/signal.h
> @@ -40,6 +40,7 @@ enum siginfo_layout {
>         SIL_TIMER,
>         SIL_POLL,
>         SIL_FAULT,
> +       SIL_FAULT_TRAPNO,
>         SIL_FAULT_MCEERR,
>         SIL_FAULT_BNDERR,
>         SIL_FAULT_PKUERR,
> diff --git a/kernel/signal.c b/kernel/signal.c
> index c3017aa8024a..7b2d61cb7411 100644
> --- a/kernel/signal.c
> +++ b/kernel/signal.c
> @@ -1194,6 +1194,7 @@ static inline bool has_si_pid_and_uid(struct kernel_siginfo *info)
>         case SIL_TIMER:
>         case SIL_POLL:
>         case SIL_FAULT:
> +       case SIL_FAULT_TRAPNO:
>         case SIL_FAULT_MCEERR:
>         case SIL_FAULT_BNDERR:
>         case SIL_FAULT_PKUERR:
> @@ -2527,6 +2528,7 @@ static void hide_si_addr_tag_bits(struct ksignal *ksig)
>  {
>         switch (siginfo_layout(ksig->sig, ksig->info.si_code)) {
>         case SIL_FAULT:
> +       case SIL_FAULT_TRAPNO:
>         case SIL_FAULT_MCEERR:
>         case SIL_FAULT_BNDERR:
>         case SIL_FAULT_PKUERR:
> @@ -3206,6 +3208,12 @@ enum siginfo_layout siginfo_layout(unsigned sig, int si_code)
>                         if ((sig == SIGBUS) &&
>                             (si_code >= BUS_MCEERR_AR) && (si_code <= BUS_MCEERR_AO))
>                                 layout = SIL_FAULT_MCEERR;
> +                       else if (IS_ENABLED(ALPHA) &&
> +                                ((sig == SIGFPE) ||
> +                                 ((sig == SIGTRAP) && (si_code == TRAP_UNK))))
> +                               layout = SIL_FAULT_TRAPNO;
> +                       else if (IS_ENABLED(SPARC) && (sig == SIGILL) && (si_code == ILL_ILLTRP))
> +                               layout = SIL_FAULT_TRAPNO;

The breakage isn't apparent here, but in later patches. These need to
become CONFIG_SPARC and CONFIG_ALPHA.


>                         else if ((sig == SIGSEGV) && (si_code == SEGV_BNDERR))
>                                 layout = SIL_FAULT_BNDERR;
>  #ifdef SEGV_PKUERR
> @@ -3317,30 +3325,22 @@ void copy_siginfo_to_external32(struct compat_siginfo *to,
>                 break;
>         case SIL_FAULT:
>                 to->si_addr = ptr_to_compat(from->si_addr);
> -#ifdef __ARCH_SI_TRAPNO
> +               break;
> +       case SIL_FAULT_TRAPNO:
> +               to->si_addr = ptr_to_compat(from->si_addr);
>                 to->si_trapno = from->si_trapno;
> -#endif
>                 break;
>         case SIL_FAULT_MCEERR:
>                 to->si_addr = ptr_to_compat(from->si_addr);
> -#ifdef __ARCH_SI_TRAPNO
> -               to->si_trapno = from->si_trapno;
> -#endif
>                 to->si_addr_lsb = from->si_addr_lsb;
>                 break;
>         case SIL_FAULT_BNDERR:
>                 to->si_addr = ptr_to_compat(from->si_addr);
> -#ifdef __ARCH_SI_TRAPNO
> -               to->si_trapno = from->si_trapno;
> -#endif
>                 to->si_lower = ptr_to_compat(from->si_lower);
>                 to->si_upper = ptr_to_compat(from->si_upper);
>                 break;
>         case SIL_FAULT_PKUERR:
>                 to->si_addr = ptr_to_compat(from->si_addr);
> -#ifdef __ARCH_SI_TRAPNO
> -               to->si_trapno = from->si_trapno;
> -#endif
>                 to->si_pkey = from->si_pkey;
>                 break;
>         case SIL_PERF_EVENT:
> @@ -3401,30 +3401,22 @@ static int post_copy_siginfo_from_user32(kernel_siginfo_t *to,
>                 break;
>         case SIL_FAULT:
>                 to->si_addr = compat_ptr(from->si_addr);
> -#ifdef __ARCH_SI_TRAPNO
> +               break;
> +       case SIL_FAULT_TRAPNO:
> +               to->si_addr = compat_ptr(from->si_addr);
>                 to->si_trapno = from->si_trapno;
> -#endif
>                 break;
>         case SIL_FAULT_MCEERR:
>                 to->si_addr = compat_ptr(from->si_addr);
> -#ifdef __ARCH_SI_TRAPNO
> -               to->si_trapno = from->si_trapno;
> -#endif
>                 to->si_addr_lsb = from->si_addr_lsb;
>                 break;
>         case SIL_FAULT_BNDERR:
>                 to->si_addr = compat_ptr(from->si_addr);
> -#ifdef __ARCH_SI_TRAPNO
> -               to->si_trapno = from->si_trapno;
> -#endif
>                 to->si_lower = compat_ptr(from->si_lower);
>                 to->si_upper = compat_ptr(from->si_upper);
>                 break;
>         case SIL_FAULT_PKUERR:
>                 to->si_addr = compat_ptr(from->si_addr);
> -#ifdef __ARCH_SI_TRAPNO
> -               to->si_trapno = from->si_trapno;
> -#endif
>                 to->si_pkey = from->si_pkey;
>                 break;
>         case SIL_PERF_EVENT:
> --
> 2.30.1

Re: [PATCH 2/3] signal: Implement SIL_FAULT_TRAPNO

[Eric W. Biederman]

Marco Elver <elver@google.com> writes:

> On Sat, 1 May 2021 at 00:54, Eric W. Biederman <ebiederm@xmission.com> wrote:
>>
>> Now that si_trapno is part of the union in _si_fault and available on
>> all architectures, add SIL_FAULT_TRAPNO and update siginfo_layout to
>> return SIL_FAULT_TRAPNO when si_trapno is actually used.
>>
>> Update the code that uses siginfo_layout to deal with SIL_FAULT_TRAPNO
>> and have the same code ignore si_trapno in in all other cases.
>>
>> Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
>> ---
>>  fs/signalfd.c          |  7 ++-----
>>  include/linux/signal.h |  1 +
>>  kernel/signal.c        | 36 ++++++++++++++----------------------
>>  3 files changed, 17 insertions(+), 27 deletions(-)
>>
>> diff --git a/fs/signalfd.c b/fs/signalfd.c
>> index 040a1142915f..126c681a30e7 100644
>> --- a/fs/signalfd.c
>> +++ b/fs/signalfd.c
>> @@ -123,15 +123,12 @@ static int signalfd_copyinfo(struct signalfd_siginfo __user *uinfo,
>>                  */
>>         case SIL_FAULT:
>>                 new.ssi_addr = (long) kinfo->si_addr;
>> -#ifdef __ARCH_SI_TRAPNO
>> +       case SIL_FAULT_TRAPNO:
>> +               new.ssi_addr = (long) kinfo->si_addr;
>>                 new.ssi_trapno = kinfo->si_trapno;
>> -#endif
>>                 break;
>>         case SIL_FAULT_MCEERR:
>>                 new.ssi_addr = (long) kinfo->si_addr;
>> -#ifdef __ARCH_SI_TRAPNO
>> -               new.ssi_trapno = kinfo->si_trapno;
>> -#endif
>>                 new.ssi_addr_lsb = (short) kinfo->si_addr_lsb;
>>                 break;
>>         case SIL_PERF_EVENT:
>> diff --git a/include/linux/signal.h b/include/linux/signal.h
>> index 1e98548d7cf6..5160fd45e5ca 100644
>> --- a/include/linux/signal.h
>> +++ b/include/linux/signal.h
>> @@ -40,6 +40,7 @@ enum siginfo_layout {
>>         SIL_TIMER,
>>         SIL_POLL,
>>         SIL_FAULT,
>> +       SIL_FAULT_TRAPNO,
>>         SIL_FAULT_MCEERR,
>>         SIL_FAULT_BNDERR,
>>         SIL_FAULT_PKUERR,
>> diff --git a/kernel/signal.c b/kernel/signal.c
>> index c3017aa8024a..7b2d61cb7411 100644
>> --- a/kernel/signal.c
>> +++ b/kernel/signal.c
>> @@ -1194,6 +1194,7 @@ static inline bool has_si_pid_and_uid(struct kernel_siginfo *info)
>>         case SIL_TIMER:
>>         case SIL_POLL:
>>         case SIL_FAULT:
>> +       case SIL_FAULT_TRAPNO:
>>         case SIL_FAULT_MCEERR:
>>         case SIL_FAULT_BNDERR:
>>         case SIL_FAULT_PKUERR:
>> @@ -2527,6 +2528,7 @@ static void hide_si_addr_tag_bits(struct ksignal *ksig)
>>  {
>>         switch (siginfo_layout(ksig->sig, ksig->info.si_code)) {
>>         case SIL_FAULT:
>> +       case SIL_FAULT_TRAPNO:
>>         case SIL_FAULT_MCEERR:
>>         case SIL_FAULT_BNDERR:
>>         case SIL_FAULT_PKUERR:
>> @@ -3206,6 +3208,12 @@ enum siginfo_layout siginfo_layout(unsigned sig, int si_code)
>>                         if ((sig == SIGBUS) &&
>>                             (si_code >= BUS_MCEERR_AR) && (si_code <= BUS_MCEERR_AO))
>>                                 layout = SIL_FAULT_MCEERR;
>> +                       else if (IS_ENABLED(ALPHA) &&
>> +                                ((sig == SIGFPE) ||
>> +                                 ((sig == SIGTRAP) && (si_code == TRAP_UNK))))
>> +                               layout = SIL_FAULT_TRAPNO;
>> +                       else if (IS_ENABLED(SPARC) && (sig == SIGILL) && (si_code == ILL_ILLTRP))
>> +                               layout = SIL_FAULT_TRAPNO;
>
> The breakage isn't apparent here, but in later patches. These need to
> become CONFIG_SPARC and CONFIG_ALPHA.

Good catch.  For some reason I thought IS_ENABLED added the CONFIG_
prefix but I looked and it doesn't.


>>                         else if ((sig == SIGSEGV) && (si_code == SEGV_BNDERR))
>>                                 layout = SIL_FAULT_BNDERR;
>>  #ifdef SEGV_PKUERR
>> @@ -3317,30 +3325,22 @@ void copy_siginfo_to_external32(struct compat_siginfo *to,
>>                 break;
>>         case SIL_FAULT:
>>                 to->si_addr = ptr_to_compat(from->si_addr);
>> -#ifdef __ARCH_SI_TRAPNO
>> +               break;
>> +       case SIL_FAULT_TRAPNO:
>> +               to->si_addr = ptr_to_compat(from->si_addr);
>>                 to->si_trapno = from->si_trapno;
>> -#endif
>>                 break;
>>         case SIL_FAULT_MCEERR:
>>                 to->si_addr = ptr_to_compat(from->si_addr);
>> -#ifdef __ARCH_SI_TRAPNO
>> -               to->si_trapno = from->si_trapno;
>> -#endif
>>                 to->si_addr_lsb = from->si_addr_lsb;
>>                 break;
>>         case SIL_FAULT_BNDERR:
>>                 to->si_addr = ptr_to_compat(from->si_addr);
>> -#ifdef __ARCH_SI_TRAPNO
>> -               to->si_trapno = from->si_trapno;
>> -#endif
>>                 to->si_lower = ptr_to_compat(from->si_lower);
>>                 to->si_upper = ptr_to_compat(from->si_upper);
>>                 break;
>>         case SIL_FAULT_PKUERR:
>>                 to->si_addr = ptr_to_compat(from->si_addr);
>> -#ifdef __ARCH_SI_TRAPNO
>> -               to->si_trapno = from->si_trapno;
>> -#endif
>>                 to->si_pkey = from->si_pkey;
>>                 break;
>>         case SIL_PERF_EVENT:
>> @@ -3401,30 +3401,22 @@ static int post_copy_siginfo_from_user32(kernel_siginfo_t *to,
>>                 break;
>>         case SIL_FAULT:
>>                 to->si_addr = compat_ptr(from->si_addr);
>> -#ifdef __ARCH_SI_TRAPNO
>> +               break;
>> +       case SIL_FAULT_TRAPNO:
>> +               to->si_addr = compat_ptr(from->si_addr);
>>                 to->si_trapno = from->si_trapno;
>> -#endif
>>                 break;
>>         case SIL_FAULT_MCEERR:
>>                 to->si_addr = compat_ptr(from->si_addr);
>> -#ifdef __ARCH_SI_TRAPNO
>> -               to->si_trapno = from->si_trapno;
>> -#endif
>>                 to->si_addr_lsb = from->si_addr_lsb;
>>                 break;
>>         case SIL_FAULT_BNDERR:
>>                 to->si_addr = compat_ptr(from->si_addr);
>> -#ifdef __ARCH_SI_TRAPNO
>> -               to->si_trapno = from->si_trapno;
>> -#endif
>>                 to->si_lower = compat_ptr(from->si_lower);
>>                 to->si_upper = compat_ptr(from->si_upper);
>>                 break;
>>         case SIL_FAULT_PKUERR:
>>                 to->si_addr = compat_ptr(from->si_addr);
>> -#ifdef __ARCH_SI_TRAPNO
>> -               to->si_trapno = from->si_trapno;
>> -#endif
>>                 to->si_pkey = from->si_pkey;
>>                 break;
>>         case SIL_PERF_EVENT:
>> --
>> 2.30.1

[PATCH 3/3] signal: Use dedicated helpers to send signals with si_trapno set

[Eric W. Biederman]

Now that si_trapno is no longer expected to be present for every fault
reported using siginfo on alpha and sparc remove the trapno parameter
from force_sig_fault, force_sig_fault_to_task and send_sig_fault.

Add two new helpers force_sig_fault_trapno and send_sig_fault_trapno
for those signals where trapno is expected to be set.

Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
---
 arch/alpha/kernel/osf_sys.c      |  2 +-
 arch/alpha/kernel/signal.c       |  4 +--
 arch/alpha/kernel/traps.c        | 24 ++++++++---------
 arch/alpha/mm/fault.c            |  4 +--
 arch/sparc/kernel/process_64.c   |  2 +-
 arch/sparc/kernel/sys_sparc_32.c |  2 +-
 arch/sparc/kernel/sys_sparc_64.c |  2 +-
 arch/sparc/kernel/traps_32.c     | 22 ++++++++--------
 arch/sparc/kernel/traps_64.c     | 44 ++++++++++++++------------------
 arch/sparc/kernel/unaligned_32.c |  2 +-
 arch/sparc/mm/fault_32.c         |  2 +-
 arch/sparc/mm/fault_64.c         |  2 +-
 include/linux/sched/signal.h     | 12 +++------
 kernel/signal.c                  | 41 +++++++++++++++++++++--------
 14 files changed, 88 insertions(+), 77 deletions(-)

diff --git a/arch/alpha/kernel/osf_sys.c b/arch/alpha/kernel/osf_sys.c
index d5367a1c6300..80c5d7fbe66a 100644
--- a/arch/alpha/kernel/osf_sys.c
+++ b/arch/alpha/kernel/osf_sys.c
@@ -878,7 +878,7 @@ SYSCALL_DEFINE5(osf_setsysinfo, unsigned long, op, void __user *, buffer,
 
 			send_sig_fault(SIGFPE, si_code,
 				       (void __user *)NULL,  /* FIXME */
-				       0, current);
+				       current);
  		}
 		return 0;
 	}
diff --git a/arch/alpha/kernel/signal.c b/arch/alpha/kernel/signal.c
index 948b89789da8..bc077babafab 100644
--- a/arch/alpha/kernel/signal.c
+++ b/arch/alpha/kernel/signal.c
@@ -219,7 +219,7 @@ do_sigreturn(struct sigcontext __user *sc)
 
 	/* Send SIGTRAP if we're single-stepping: */
 	if (ptrace_cancel_bpt (current)) {
-		send_sig_fault(SIGTRAP, TRAP_BRKPT, (void __user *) regs->pc, 0,
+		send_sig_fault(SIGTRAP, TRAP_BRKPT, (void __user *) regs->pc,
 			       current);
 	}
 	return;
@@ -247,7 +247,7 @@ do_rt_sigreturn(struct rt_sigframe __user *frame)
 
 	/* Send SIGTRAP if we're single-stepping: */
 	if (ptrace_cancel_bpt (current)) {
-		send_sig_fault(SIGTRAP, TRAP_BRKPT, (void __user *) regs->pc, 0,
+		send_sig_fault(SIGTRAP, TRAP_BRKPT, (void __user *) regs->pc,
 			       current);
 	}
 	return;
diff --git a/arch/alpha/kernel/traps.c b/arch/alpha/kernel/traps.c
index 921d4b6e4d95..0dddf9ecc1f4 100644
--- a/arch/alpha/kernel/traps.c
+++ b/arch/alpha/kernel/traps.c
@@ -227,7 +227,7 @@ do_entArith(unsigned long summary, unsigned long write_mask,
 	}
 	die_if_kernel("Arithmetic fault", regs, 0, NULL);
 
-	send_sig_fault(SIGFPE, si_code, (void __user *) regs->pc, 0, current);
+	send_sig_fault_trapno(SIGFPE, si_code, (void __user *) regs->pc, 0, current);
 }
 
 asmlinkage void
@@ -268,12 +268,12 @@ do_entIF(unsigned long type, struct pt_regs *regs)
 			regs->pc -= 4;	/* make pc point to former bpt */
 		}
 
-		send_sig_fault(SIGTRAP, TRAP_BRKPT, (void __user *)regs->pc, 0,
+		send_sig_fault(SIGTRAP, TRAP_BRKPT, (void __user *)regs->pc,
 			       current);
 		return;
 
 	      case 1: /* bugcheck */
-		send_sig_fault(SIGTRAP, TRAP_UNK, (void __user *) regs->pc, 0,
+		send_sig_fault(SIGTRAP, TRAP_UNK, (void __user *) regs->pc,
 			       current);
 		return;
 		
@@ -335,8 +335,8 @@ do_entIF(unsigned long type, struct pt_regs *regs)
 			break;
 		}
 
-		send_sig_fault(signo, code, (void __user *) regs->pc, regs->r16,
-			       current);
+		send_sig_fault_trapno(signo, code, (void __user *) regs->pc,
+				      regs->r16, current);
 		return;
 
 	      case 4: /* opDEC */
@@ -360,9 +360,9 @@ do_entIF(unsigned long type, struct pt_regs *regs)
 			if (si_code == 0)
 				return;
 			if (si_code > 0) {
-				send_sig_fault(SIGFPE, si_code,
-					       (void __user *) regs->pc, 0,
-					       current);
+				send_sig_fault_trapno(SIGFPE, si_code,
+						      (void __user *) regs->pc,
+						      0, current);
 				return;
 			}
 		}
@@ -387,7 +387,7 @@ do_entIF(unsigned long type, struct pt_regs *regs)
 		      ;
 	}
 
-	send_sig_fault(SIGILL, ILL_ILLOPC, (void __user *)regs->pc, 0, current);
+	send_sig_fault(SIGILL, ILL_ILLOPC, (void __user *)regs->pc, current);
 }
 
 /* There is an ifdef in the PALcode in MILO that enables a 
@@ -402,7 +402,7 @@ do_entDbg(struct pt_regs *regs)
 {
 	die_if_kernel("Instruction fault", regs, 0, NULL);
 
-	force_sig_fault(SIGILL, ILL_ILLOPC, (void __user *)regs->pc, 0);
+	force_sig_fault(SIGILL, ILL_ILLOPC, (void __user *)regs->pc);
 }
 
 
@@ -964,12 +964,12 @@ do_entUnaUser(void __user * va, unsigned long opcode,
 			si_code = SEGV_MAPERR;
 		mmap_read_unlock(mm);
 	}
-	send_sig_fault(SIGSEGV, si_code, va, 0, current);
+	send_sig_fault(SIGSEGV, si_code, va, current);
 	return;
 
 give_sigbus:
 	regs->pc -= 4;
-	send_sig_fault(SIGBUS, BUS_ADRALN, va, 0, current);
+	send_sig_fault(SIGBUS, BUS_ADRALN, va, current);
 	return;
 }
 
diff --git a/arch/alpha/mm/fault.c b/arch/alpha/mm/fault.c
index 09172f017efc..eee5102c3d88 100644
--- a/arch/alpha/mm/fault.c
+++ b/arch/alpha/mm/fault.c
@@ -219,13 +219,13 @@ do_page_fault(unsigned long address, unsigned long mmcsr,
 	mmap_read_unlock(mm);
 	/* Send a sigbus, regardless of whether we were in kernel
 	   or user mode.  */
-	force_sig_fault(SIGBUS, BUS_ADRERR, (void __user *) address, 0);
+	force_sig_fault(SIGBUS, BUS_ADRERR, (void __user *) address);
 	if (!user_mode(regs))
 		goto no_context;
 	return;
 
  do_sigsegv:
-	force_sig_fault(SIGSEGV, si_code, (void __user *) address, 0);
+	force_sig_fault(SIGSEGV, si_code, (void __user *) address);
 	return;
 
 #ifdef CONFIG_ALPHA_LARGE_VMALLOC
diff --git a/arch/sparc/kernel/process_64.c b/arch/sparc/kernel/process_64.c
index 7afd0a859a78..29e67854d5a4 100644
--- a/arch/sparc/kernel/process_64.c
+++ b/arch/sparc/kernel/process_64.c
@@ -518,7 +518,7 @@ void synchronize_user_stack(void)
 
 static void stack_unaligned(unsigned long sp)
 {
-	force_sig_fault(SIGBUS, BUS_ADRALN, (void __user *) sp, 0);
+	force_sig_fault(SIGBUS, BUS_ADRALN, (void __user *) sp);
 }
 
 static const char uwfault32[] = KERN_INFO \
diff --git a/arch/sparc/kernel/sys_sparc_32.c b/arch/sparc/kernel/sys_sparc_32.c
index be77538bc038..082a551897ed 100644
--- a/arch/sparc/kernel/sys_sparc_32.c
+++ b/arch/sparc/kernel/sys_sparc_32.c
@@ -151,7 +151,7 @@ sparc_breakpoint (struct pt_regs *regs)
 #ifdef DEBUG_SPARC_BREAKPOINT
         printk ("TRAP: Entering kernel PC=%x, nPC=%x\n", regs->pc, regs->npc);
 #endif
-	force_sig_fault(SIGTRAP, TRAP_BRKPT, (void __user *)regs->pc, 0);
+	force_sig_fault(SIGTRAP, TRAP_BRKPT, (void __user *)regs->pc);
 
 #ifdef DEBUG_SPARC_BREAKPOINT
 	printk ("TRAP: Returning to space: PC=%x nPC=%x\n", regs->pc, regs->npc);
diff --git a/arch/sparc/kernel/sys_sparc_64.c b/arch/sparc/kernel/sys_sparc_64.c
index 6b92fadb6ec7..1e9a9e016237 100644
--- a/arch/sparc/kernel/sys_sparc_64.c
+++ b/arch/sparc/kernel/sys_sparc_64.c
@@ -514,7 +514,7 @@ asmlinkage void sparc_breakpoint(struct pt_regs *regs)
 #ifdef DEBUG_SPARC_BREAKPOINT
         printk ("TRAP: Entering kernel PC=%lx, nPC=%lx\n", regs->tpc, regs->tnpc);
 #endif
-	force_sig_fault(SIGTRAP, TRAP_BRKPT, (void __user *)regs->tpc, 0);
+	force_sig_fault(SIGTRAP, TRAP_BRKPT, (void __user *)regs->tpc);
 #ifdef DEBUG_SPARC_BREAKPOINT
 	printk ("TRAP: Returning to space: PC=%lx nPC=%lx\n", regs->tpc, regs->tnpc);
 #endif
diff --git a/arch/sparc/kernel/traps_32.c b/arch/sparc/kernel/traps_32.c
index 247a0d9683b2..5630e5a395e0 100644
--- a/arch/sparc/kernel/traps_32.c
+++ b/arch/sparc/kernel/traps_32.c
@@ -102,8 +102,8 @@ void do_hw_interrupt(struct pt_regs *regs, unsigned long type)
 	if(regs->psr & PSR_PS)
 		die_if_kernel("Kernel bad trap", regs);
 
-	force_sig_fault(SIGILL, ILL_ILLTRP,
-			(void __user *)regs->pc, type - 0x80);
+	force_sig_fault_trapno(SIGILL, ILL_ILLTRP,
+			       (void __user *)regs->pc, type - 0x80);
 }
 
 void do_illegal_instruction(struct pt_regs *regs, unsigned long pc, unsigned long npc,
@@ -116,7 +116,7 @@ void do_illegal_instruction(struct pt_regs *regs, unsigned long pc, unsigned lon
 	       regs->pc, *(unsigned long *)regs->pc);
 #endif
 
-	send_sig_fault(SIGILL, ILL_ILLOPC, (void __user *)pc, 0, current);
+	send_sig_fault(SIGILL, ILL_ILLOPC, (void __user *)pc, current);
 }
 
 void do_priv_instruction(struct pt_regs *regs, unsigned long pc, unsigned long npc,
@@ -124,7 +124,7 @@ void do_priv_instruction(struct pt_regs *regs, unsigned long pc, unsigned long n
 {
 	if(psr & PSR_PS)
 		die_if_kernel("Penguin instruction from Penguin mode??!?!", regs);
-	send_sig_fault(SIGILL, ILL_PRVOPC, (void __user *)pc, 0, current);
+	send_sig_fault(SIGILL, ILL_PRVOPC, (void __user *)pc, current);
 }
 
 /* XXX User may want to be allowed to do this. XXX */
@@ -145,7 +145,7 @@ void do_memaccess_unaligned(struct pt_regs *regs, unsigned long pc, unsigned lon
 #endif
 	send_sig_fault(SIGBUS, BUS_ADRALN,
 		       /* FIXME: Should dig out mna address */ (void *)0,
-		       0, current);
+		       current);
 }
 
 static unsigned long init_fsr = 0x0UL;
@@ -291,7 +291,7 @@ void do_fpe_trap(struct pt_regs *regs, unsigned long pc, unsigned long npc,
 		else if (fsr & 0x01)
 			code = FPE_FLTRES;
 	}
-	send_sig_fault(SIGFPE, code, (void __user *)pc, 0, fpt);
+	send_sig_fault(SIGFPE, code, (void __user *)pc, fpt);
 #ifndef CONFIG_SMP
 	last_task_used_math = NULL;
 #endif
@@ -305,7 +305,7 @@ void handle_tag_overflow(struct pt_regs *regs, unsigned long pc, unsigned long n
 {
 	if(psr & PSR_PS)
 		die_if_kernel("Penguin overflow trap from kernel mode", regs);
-	send_sig_fault(SIGEMT, EMT_TAGOVF, (void __user *)pc, 0, current);
+	send_sig_fault(SIGEMT, EMT_TAGOVF, (void __user *)pc, current);
 }
 
 void handle_watchpoint(struct pt_regs *regs, unsigned long pc, unsigned long npc,
@@ -327,13 +327,13 @@ void handle_reg_access(struct pt_regs *regs, unsigned long pc, unsigned long npc
 	printk("Register Access Exception at PC %08lx NPC %08lx PSR %08lx\n",
 	       pc, npc, psr);
 #endif
-	force_sig_fault(SIGBUS, BUS_OBJERR, (void __user *)pc, 0);
+	force_sig_fault(SIGBUS, BUS_OBJERR, (void __user *)pc);
 }
 
 void handle_cp_disabled(struct pt_regs *regs, unsigned long pc, unsigned long npc,
 			unsigned long psr)
 {
-	send_sig_fault(SIGILL, ILL_COPROC, (void __user *)pc, 0, current);
+	send_sig_fault(SIGILL, ILL_COPROC, (void __user *)pc, current);
 }
 
 void handle_cp_exception(struct pt_regs *regs, unsigned long pc, unsigned long npc,
@@ -343,13 +343,13 @@ void handle_cp_exception(struct pt_regs *regs, unsigned long pc, unsigned long n
 	printk("Co-Processor Exception at PC %08lx NPC %08lx PSR %08lx\n",
 	       pc, npc, psr);
 #endif
-	send_sig_fault(SIGILL, ILL_COPROC, (void __user *)pc, 0, current);
+	send_sig_fault(SIGILL, ILL_COPROC, (void __user *)pc, current);
 }
 
 void handle_hw_divzero(struct pt_regs *regs, unsigned long pc, unsigned long npc,
 		       unsigned long psr)
 {
-	send_sig_fault(SIGFPE, FPE_INTDIV, (void __user *)pc, 0, current);
+	send_sig_fault(SIGFPE, FPE_INTDIV, (void __user *)pc, current);
 }
 
 #ifdef CONFIG_DEBUG_BUGVERBOSE
diff --git a/arch/sparc/kernel/traps_64.c b/arch/sparc/kernel/traps_64.c
index a850dccd78ea..6863025ed56d 100644
--- a/arch/sparc/kernel/traps_64.c
+++ b/arch/sparc/kernel/traps_64.c
@@ -107,8 +107,8 @@ void bad_trap(struct pt_regs *regs, long lvl)
 		regs->tpc &= 0xffffffff;
 		regs->tnpc &= 0xffffffff;
 	}
-	force_sig_fault(SIGILL, ILL_ILLTRP,
-			(void __user *)regs->tpc, lvl);
+	force_sig_fault_trapno(SIGILL, ILL_ILLTRP,
+			       (void __user *)regs->tpc, lvl);
 }
 
 void bad_trap_tl1(struct pt_regs *regs, long lvl)
@@ -201,8 +201,7 @@ void spitfire_insn_access_exception(struct pt_regs *regs, unsigned long sfsr, un
 		regs->tpc &= 0xffffffff;
 		regs->tnpc &= 0xffffffff;
 	}
-	force_sig_fault(SIGSEGV, SEGV_MAPERR,
-			(void __user *)regs->tpc, 0);
+	force_sig_fault(SIGSEGV, SEGV_MAPERR, (void __user *)regs->tpc);
 out:
 	exception_exit(prev_state);
 }
@@ -237,7 +236,7 @@ void sun4v_insn_access_exception(struct pt_regs *regs, unsigned long addr, unsig
 		regs->tpc &= 0xffffffff;
 		regs->tnpc &= 0xffffffff;
 	}
-	force_sig_fault(SIGSEGV, SEGV_MAPERR, (void __user *) addr, 0);
+	force_sig_fault(SIGSEGV, SEGV_MAPERR, (void __user *) addr);
 }
 
 void sun4v_insn_access_exception_tl1(struct pt_regs *regs, unsigned long addr, unsigned long type_ctx)
@@ -321,7 +320,7 @@ void spitfire_data_access_exception(struct pt_regs *regs, unsigned long sfsr, un
 	if (is_no_fault_exception(regs))
 		return;
 
-	force_sig_fault(SIGSEGV, SEGV_MAPERR, (void __user *)sfar, 0);
+	force_sig_fault(SIGSEGV, SEGV_MAPERR, (void __user *)sfar);
 out:
 	exception_exit(prev_state);
 }
@@ -385,13 +384,13 @@ void sun4v_data_access_exception(struct pt_regs *regs, unsigned long addr, unsig
 	 */
 	switch (type) {
 	case HV_FAULT_TYPE_INV_ASI:
-		force_sig_fault(SIGILL, ILL_ILLADR, (void __user *)addr, 0);
+		force_sig_fault(SIGILL, ILL_ILLADR, (void __user *)addr);
 		break;
 	case HV_FAULT_TYPE_MCD_DIS:
-		force_sig_fault(SIGSEGV, SEGV_ACCADI, (void __user *)addr, 0);
+		force_sig_fault(SIGSEGV, SEGV_ACCADI, (void __user *)addr);
 		break;
 	default:
-		force_sig_fault(SIGSEGV, SEGV_MAPERR, (void __user *)addr, 0);
+		force_sig_fault(SIGSEGV, SEGV_MAPERR, (void __user *)addr);
 		break;
 	}
 }
@@ -568,7 +567,7 @@ static void spitfire_ue_log(unsigned long afsr, unsigned long afar, unsigned lon
 		regs->tpc &= 0xffffffff;
 		regs->tnpc &= 0xffffffff;
 	}
-	force_sig_fault(SIGBUS, BUS_OBJERR, (void *)0, 0);
+	force_sig_fault(SIGBUS, BUS_OBJERR, (void *)0);
 }
 
 void spitfire_access_error(struct pt_regs *regs, unsigned long status_encoded, unsigned long afar)
@@ -2069,8 +2068,7 @@ void do_mcd_err(struct pt_regs *regs, struct sun4v_error_entry ent)
 	/* Send SIGSEGV to the userspace process with the right signal
 	 * code
 	 */
-	force_sig_fault(SIGSEGV, SEGV_ADIDERR, (void __user *)ent.err_raddr,
-			0);
+	force_sig_fault(SIGSEGV, SEGV_ADIDERR, (void __user *)ent.err_raddr);
 }
 
 /* We run with %pil set to PIL_NORMAL_MAX and PSTATE_IE enabled in %pstate.
@@ -2184,7 +2182,7 @@ bool sun4v_nonresum_error_user_handled(struct pt_regs *regs,
 	}
 	if (attrs & SUN4V_ERR_ATTRS_PIO) {
 		force_sig_fault(SIGBUS, BUS_ADRERR,
-				(void __user *)sun4v_get_vaddr(regs), 0);
+				(void __user *)sun4v_get_vaddr(regs));
 		return true;
 	}
 
@@ -2340,8 +2338,7 @@ static void do_fpe_common(struct pt_regs *regs)
 			else if (fsr & 0x01)
 				code = FPE_FLTRES;
 		}
-		force_sig_fault(SIGFPE, code,
-				(void __user *)regs->tpc, 0);
+		force_sig_fault(SIGFPE, code, (void __user *)regs->tpc);
 	}
 }
 
@@ -2395,8 +2392,7 @@ void do_tof(struct pt_regs *regs)
 		regs->tpc &= 0xffffffff;
 		regs->tnpc &= 0xffffffff;
 	}
-	force_sig_fault(SIGEMT, EMT_TAGOVF,
-			(void __user *)regs->tpc, 0);
+	force_sig_fault(SIGEMT, EMT_TAGOVF, (void __user *)regs->tpc);
 out:
 	exception_exit(prev_state);
 }
@@ -2415,8 +2411,7 @@ void do_div0(struct pt_regs *regs)
 		regs->tpc &= 0xffffffff;
 		regs->tnpc &= 0xffffffff;
 	}
-	force_sig_fault(SIGFPE, FPE_INTDIV,
-			(void __user *)regs->tpc, 0);
+	force_sig_fault(SIGFPE, FPE_INTDIV, (void __user *)regs->tpc);
 out:
 	exception_exit(prev_state);
 }
@@ -2612,7 +2607,7 @@ void do_illegal_instruction(struct pt_regs *regs)
 			}
 		}
 	}
-	force_sig_fault(SIGILL, ILL_ILLOPC, (void __user *)pc, 0);
+	force_sig_fault(SIGILL, ILL_ILLOPC, (void __user *)pc);
 out:
 	exception_exit(prev_state);
 }
@@ -2632,7 +2627,7 @@ void mem_address_unaligned(struct pt_regs *regs, unsigned long sfar, unsigned lo
 	if (is_no_fault_exception(regs))
 		return;
 
-	force_sig_fault(SIGBUS, BUS_ADRALN, (void __user *)sfar, 0);
+	force_sig_fault(SIGBUS, BUS_ADRALN, (void __user *)sfar);
 out:
 	exception_exit(prev_state);
 }
@@ -2650,7 +2645,7 @@ void sun4v_do_mna(struct pt_regs *regs, unsigned long addr, unsigned long type_c
 	if (is_no_fault_exception(regs))
 		return;
 
-	force_sig_fault(SIGBUS, BUS_ADRALN, (void __user *) addr, 0);
+	force_sig_fault(SIGBUS, BUS_ADRALN, (void __user *) addr);
 }
 
 /* sun4v_mem_corrupt_detect_precise() - Handle precise exception on an ADI
@@ -2697,7 +2692,7 @@ void sun4v_mem_corrupt_detect_precise(struct pt_regs *regs, unsigned long addr,
 		regs->tpc &= 0xffffffff;
 		regs->tnpc &= 0xffffffff;
 	}
-	force_sig_fault(SIGSEGV, SEGV_ADIPERR, (void __user *)addr, 0);
+	force_sig_fault(SIGSEGV, SEGV_ADIPERR, (void __user *)addr);
 }
 
 void do_privop(struct pt_regs *regs)
@@ -2712,8 +2707,7 @@ void do_privop(struct pt_regs *regs)
 		regs->tpc &= 0xffffffff;
 		regs->tnpc &= 0xffffffff;
 	}
-	force_sig_fault(SIGILL, ILL_PRVOPC,
-			(void __user *)regs->tpc, 0);
+	force_sig_fault(SIGILL, ILL_PRVOPC, (void __user *)regs->tpc);
 out:
 	exception_exit(prev_state);
 }
diff --git a/arch/sparc/kernel/unaligned_32.c b/arch/sparc/kernel/unaligned_32.c
index ef5c5207c9ff..455f0258c745 100644
--- a/arch/sparc/kernel/unaligned_32.c
+++ b/arch/sparc/kernel/unaligned_32.c
@@ -278,5 +278,5 @@ asmlinkage void user_unaligned_trap(struct pt_regs *regs, unsigned int insn)
 {
 	send_sig_fault(SIGBUS, BUS_ADRALN,
 		       (void __user *)safe_compute_effective_address(regs, insn),
-		       0, current);
+		       current);
 }
diff --git a/arch/sparc/mm/fault_32.c b/arch/sparc/mm/fault_32.c
index de2031c2b2d7..fa858626b85b 100644
--- a/arch/sparc/mm/fault_32.c
+++ b/arch/sparc/mm/fault_32.c
@@ -83,7 +83,7 @@ static void __do_fault_siginfo(int code, int sig, struct pt_regs *regs,
 		show_signal_msg(regs, sig, code,
 				addr, current);
 
-	force_sig_fault(sig, code, (void __user *) addr, 0);
+	force_sig_fault(sig, code, (void __user *) addr);
 }
 
 static unsigned long compute_si_addr(struct pt_regs *regs, int text_fault)
diff --git a/arch/sparc/mm/fault_64.c b/arch/sparc/mm/fault_64.c
index 0a6bcc85fba7..9a9652a15fed 100644
--- a/arch/sparc/mm/fault_64.c
+++ b/arch/sparc/mm/fault_64.c
@@ -176,7 +176,7 @@ static void do_fault_siginfo(int code, int sig, struct pt_regs *regs,
 	if (unlikely(show_unhandled_signals))
 		show_signal_msg(regs, sig, code, addr, current);
 
-	force_sig_fault(sig, code, (void __user *) addr, 0);
+	force_sig_fault(sig, code, (void __user *) addr);
 }
 
 static unsigned int get_fault_insn(struct pt_regs *regs, unsigned int insn)
diff --git a/include/linux/sched/signal.h b/include/linux/sched/signal.h
index 3f6a0fcaa10c..7daa425f3055 100644
--- a/include/linux/sched/signal.h
+++ b/include/linux/sched/signal.h
@@ -298,11 +298,6 @@ static inline void kernel_signal_stop(void)
 
 	schedule();
 }
-#ifdef __ARCH_SI_TRAPNO
-# define ___ARCH_SI_TRAPNO(_a1) , _a1
-#else
-# define ___ARCH_SI_TRAPNO(_a1)
-#endif
 #ifdef __ia64__
 # define ___ARCH_SI_IA64(_a1, _a2, _a3) , _a1, _a2, _a3
 #else
@@ -310,14 +305,11 @@ static inline void kernel_signal_stop(void)
 #endif
 
 int force_sig_fault_to_task(int sig, int code, void __user *addr
-	___ARCH_SI_TRAPNO(int trapno)
 	___ARCH_SI_IA64(int imm, unsigned int flags, unsigned long isr)
 	, struct task_struct *t);
 int force_sig_fault(int sig, int code, void __user *addr
-	___ARCH_SI_TRAPNO(int trapno)
 	___ARCH_SI_IA64(int imm, unsigned int flags, unsigned long isr));
 int send_sig_fault(int sig, int code, void __user *addr
-	___ARCH_SI_TRAPNO(int trapno)
 	___ARCH_SI_IA64(int imm, unsigned int flags, unsigned long isr)
 	, struct task_struct *t);
 
@@ -327,6 +319,10 @@ int send_sig_mceerr(int code, void __user *, short, struct task_struct *);
 int force_sig_bnderr(void __user *addr, void __user *lower, void __user *upper);
 int force_sig_pkuerr(void __user *addr, u32 pkey);
 
+int force_sig_fault_trapno(int sig, int code, void __user *addr, int trapno);
+int send_sig_fault_trapno(int sig, int code, void __user *addr, int trapno,
+			  struct task_struct *task);
+
 int force_sig_ptrace_errno_trap(int errno, void __user *addr);
 
 extern int send_sig_info(int, struct kernel_siginfo *, struct task_struct *);
diff --git a/kernel/signal.c b/kernel/signal.c
index 7b2d61cb7411..0517ff950d38 100644
--- a/kernel/signal.c
+++ b/kernel/signal.c
@@ -1651,7 +1651,6 @@ void force_sigsegv(int sig)
 }
 
 int force_sig_fault_to_task(int sig, int code, void __user *addr
-	___ARCH_SI_TRAPNO(int trapno)
 	___ARCH_SI_IA64(int imm, unsigned int flags, unsigned long isr)
 	, struct task_struct *t)
 {
@@ -1662,9 +1661,6 @@ int force_sig_fault_to_task(int sig, int code, void __user *addr
 	info.si_errno = 0;
 	info.si_code  = code;
 	info.si_addr  = addr;
-#ifdef __ARCH_SI_TRAPNO
-	info.si_trapno = trapno;
-#endif
 #ifdef __ia64__
 	info.si_imm = imm;
 	info.si_flags = flags;
@@ -1674,16 +1670,13 @@ int force_sig_fault_to_task(int sig, int code, void __user *addr
 }
 
 int force_sig_fault(int sig, int code, void __user *addr
-	___ARCH_SI_TRAPNO(int trapno)
 	___ARCH_SI_IA64(int imm, unsigned int flags, unsigned long isr))
 {
 	return force_sig_fault_to_task(sig, code, addr
-				       ___ARCH_SI_TRAPNO(trapno)
 				       ___ARCH_SI_IA64(imm, flags, isr), current);
 }
 
 int send_sig_fault(int sig, int code, void __user *addr
-	___ARCH_SI_TRAPNO(int trapno)
 	___ARCH_SI_IA64(int imm, unsigned int flags, unsigned long isr)
 	, struct task_struct *t)
 {
@@ -1694,9 +1687,6 @@ int send_sig_fault(int sig, int code, void __user *addr
 	info.si_errno = 0;
 	info.si_code  = code;
 	info.si_addr  = addr;
-#ifdef __ARCH_SI_TRAPNO
-	info.si_trapno = trapno;
-#endif
 #ifdef __ia64__
 	info.si_imm = imm;
 	info.si_flags = flags;
@@ -1763,6 +1753,37 @@ int force_sig_pkuerr(void __user *addr, u32 pkey)
 }
 #endif
 
+#if IS_ENABLED(SPARC)
+int force_sig_fault_trapno(int sig, int code, void __user *addr, int trapno)
+{
+	struct kernel_siginfo info;
+
+	clear_siginfo(&info);
+	info.si_signo = sig;
+	info.si_errno = 0;
+	info.si_code  = code;
+	info.si_addr  = addr;
+	info.si_trapno = trapno;
+	return force_sig_info(&info);
+}
+#endif
+
+#if IS_ENABLED(ALPHA)
+int send_sig_fault_trapno(int sig, int code, void __user *addr, int trapno,
+			  struct task_struct *t)
+{
+	struct kernel_siginfo info;
+
+	clear_siginfo(&info);
+	info.si_signo = sig;
+	info.si_errno = 0;
+	info.si_code  = code;
+	info.si_addr  = addr;
+	info.si_trapno = trapno;
+	return send_sig_info(info.si_signo, &info, t);
+}
+#endif
+
 /* For the crazy architectures that include trap information in
  * the errno field, instead of an actual errno value.
  */
-- 
2.30.1

Re: [PATCH 3/3] signal: Use dedicated helpers to send signals with si_trapno set

[Marco Elver]

On Sat, 1 May 2021 at 00:55, Eric W. Biederman <ebiederm@xmission.com> wrote:
>
> Now that si_trapno is no longer expected to be present for every fault
> reported using siginfo on alpha and sparc remove the trapno parameter
> from force_sig_fault, force_sig_fault_to_task and send_sig_fault.
>
> Add two new helpers force_sig_fault_trapno and send_sig_fault_trapno
> for those signals where trapno is expected to be set.
>
> Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
> ---
>  arch/alpha/kernel/osf_sys.c      |  2 +-
>  arch/alpha/kernel/signal.c       |  4 +--
>  arch/alpha/kernel/traps.c        | 24 ++++++++---------
>  arch/alpha/mm/fault.c            |  4 +--
>  arch/sparc/kernel/process_64.c   |  2 +-
>  arch/sparc/kernel/sys_sparc_32.c |  2 +-
>  arch/sparc/kernel/sys_sparc_64.c |  2 +-
>  arch/sparc/kernel/traps_32.c     | 22 ++++++++--------
>  arch/sparc/kernel/traps_64.c     | 44 ++++++++++++++------------------
>  arch/sparc/kernel/unaligned_32.c |  2 +-
>  arch/sparc/mm/fault_32.c         |  2 +-
>  arch/sparc/mm/fault_64.c         |  2 +-
>  include/linux/sched/signal.h     | 12 +++------
>  kernel/signal.c                  | 41 +++++++++++++++++++++--------
>  14 files changed, 88 insertions(+), 77 deletions(-)

This still breaks sparc64:

> sparc64-linux-gnu-ld: arch/sparc/kernel/traps_64.o: in function `bad_trap':
> (.text+0x2a4): undefined reference to `force_sig_fault_trapno'

[...]
> +#if IS_ENABLED(SPARC)

This should be 'IS_ENABLED(CONFIG_SPARC)'.

> +int force_sig_fault_trapno(int sig, int code, void __user *addr, int trapno)
> +{
> +       struct kernel_siginfo info;
> +
> +       clear_siginfo(&info);
> +       info.si_signo = sig;
> +       info.si_errno = 0;
> +       info.si_code  = code;
> +       info.si_addr  = addr;
> +       info.si_trapno = trapno;
> +       return force_sig_info(&info);
> +}
> +#endif
> +
> +#if IS_ENABLED(ALPHA)

CONFIG_ALPHA


> +int send_sig_fault_trapno(int sig, int code, void __user *addr, int trapno,
> +                         struct task_struct *t)
> +{
> +       struct kernel_siginfo info;
> +
> +       clear_siginfo(&info);
> +       info.si_signo = sig;
> +       info.si_errno = 0;
> +       info.si_code  = code;
> +       info.si_addr  = addr;
> +       info.si_trapno = trapno;
> +       return send_sig_info(info.si_signo, &info, t);
> +}
> +#endif
> +
>  /* For the crazy architectures that include trap information in
>   * the errno field, instead of an actual errno value.
>   */
> --
> 2.30.1
>

[PATCH 4/3] signal: Remove __ARCH_SI_TRAPNO

[Eric W. Biederman]

Now that this define is no longer used remove it from the kernel.

Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
---
 arch/alpha/include/uapi/asm/siginfo.h | 2 --
 arch/mips/include/uapi/asm/siginfo.h  | 2 --
 arch/sparc/include/uapi/asm/siginfo.h | 3 ---
 3 files changed, 7 deletions(-)

diff --git a/arch/alpha/include/uapi/asm/siginfo.h b/arch/alpha/include/uapi/asm/siginfo.h
index 6e1a2af2f962..e08eae88182b 100644
--- a/arch/alpha/include/uapi/asm/siginfo.h
+++ b/arch/alpha/include/uapi/asm/siginfo.h
@@ -2,8 +2,6 @@
 #ifndef _ALPHA_SIGINFO_H
 #define _ALPHA_SIGINFO_H
 
-#define __ARCH_SI_TRAPNO
-
 #include <asm-generic/siginfo.h>
 
 #endif
diff --git a/arch/mips/include/uapi/asm/siginfo.h b/arch/mips/include/uapi/asm/siginfo.h
index c34c7eef0a1c..8cb8bd061a68 100644
--- a/arch/mips/include/uapi/asm/siginfo.h
+++ b/arch/mips/include/uapi/asm/siginfo.h
@@ -10,9 +10,7 @@
 #ifndef _UAPI_ASM_SIGINFO_H
 #define _UAPI_ASM_SIGINFO_H
 
-
 #define __ARCH_SIGEV_PREAMBLE_SIZE (sizeof(long) + 2*sizeof(int))
-#undef __ARCH_SI_TRAPNO /* exception code needs to fill this ...  */
 
 #define __ARCH_HAS_SWAPPED_SIGINFO
 
diff --git a/arch/sparc/include/uapi/asm/siginfo.h b/arch/sparc/include/uapi/asm/siginfo.h
index 68bdde4c2a2e..0e7c27522aed 100644
--- a/arch/sparc/include/uapi/asm/siginfo.h
+++ b/arch/sparc/include/uapi/asm/siginfo.h
@@ -8,9 +8,6 @@
 
 #endif /* defined(__sparc__) && defined(__arch64__) */
 
-
-#define __ARCH_SI_TRAPNO
-
 #include <asm-generic/siginfo.h>
 
 
-- 
2.30.1

Is perf_sigtrap synchronous?

[Eric W. Biederman]

I am looking at perf_sigtrap and I am confused by the code.


	/*
	 * We'd expect this to only occur if the irq_work is delayed and either
	 * ctx->task or current has changed in the meantime. This can be the
	 * case on architectures that do not implement arch_irq_work_raise().
	 */
	if (WARN_ON_ONCE(event->ctx->task != current))
		return;

	/*
	 * perf_pending_event() can race with the task exiting.
	 */
	if (current->flags & PF_EXITING)
		return;


It performs tests that absolutely can never fail if we are talking about
a synchronous exception.  The code force_sig family of functions only
make sense to use with and are only safe to use with synchronous
exceptions.

Are the tests in perf_sigtrap necessary or is perf_sigtrap not reporting
a synchronous event?

Eric

Re: Is perf_sigtrap synchronous?

[Marco Elver]

On Sat, 1 May 2021 at 01:23, Eric W. Biederman <ebiederm@xmission.com> wrote:
>
> I am looking at perf_sigtrap and I am confused by the code.
>
>
>         /*
>          * We'd expect this to only occur if the irq_work is delayed and either
>          * ctx->task or current has changed in the meantime. This can be the
>          * case on architectures that do not implement arch_irq_work_raise().
>          */
>         if (WARN_ON_ONCE(event->ctx->task != current))
>                 return;
>
>         /*
>          * perf_pending_event() can race with the task exiting.
>          */
>         if (current->flags & PF_EXITING)
>                 return;
>
>
> It performs tests that absolutely can never fail if we are talking about
> a synchronous exception.  The code force_sig family of functions only
> make sense to use with and are only safe to use with synchronous
> exceptions.
>
> Are the tests in perf_sigtrap necessary or is perf_sigtrap not reporting
> a synchronous event?

Yes it's synchronous, insofar that the user will receive the signal
right when the event happens (I've tested this extensively, also see
tools/testing/selftests/perf_events). Of course, there's some effort
involved from the point where the event triggered to actually safely
delivering the signal. In particular, for HW events, these arrive in
NMI, and we can't do much in NMI, and therefore will queue an
irq_work.

On architectures that properly implement irq_work, it will do a
self-IPI, so that once it is safe to do so, another interrupt is
delivered where we process the event and do the force_sig_info(). The
task where the event occurred never got a chance to run -- except for
bad architectures with broken irq_work, and the first WARN_ON() is
there so we don't crash the kernel if somebody botched their irq_work.

Since we're talking about various HW events, these can still trigger
while the task is exiting, before perf_event_exit_task() being called
during do_exit(). That's why we have the 2nd check.

Thanks,
-- Marco

[PATCH 5/3] signal: Rename SIL_PERF_EVENT SIL_FAULT_PERF_EVENT for consistency

[Eric W. Biederman]

It helps to know which part of the siginfo structure the siginfo_layout
value is talking about.
---
 fs/signalfd.c          |  2 +-
 include/linux/signal.h |  2 +-
 kernel/signal.c        | 10 +++++-----
 3 files changed, 7 insertions(+), 7 deletions(-)

diff --git a/fs/signalfd.c b/fs/signalfd.c
index e87e59581653..83130244f653 100644
--- a/fs/signalfd.c
+++ b/fs/signalfd.c
@@ -132,7 +132,7 @@ static int signalfd_copyinfo(struct signalfd_siginfo __user *uinfo,
 		new.ssi_addr = (long) kinfo->si_addr;
 		new.ssi_addr_lsb = (short) kinfo->si_addr_lsb;
 		break;
-	case SIL_PERF_EVENT:
+	case SIL_FAULT_PERF_EVENT:
 		new.ssi_addr = (long) kinfo->si_addr;
 		new.ssi_perf = kinfo->si_perf;
 		break;
diff --git a/include/linux/signal.h b/include/linux/signal.h
index 5160fd45e5ca..ed896d790e46 100644
--- a/include/linux/signal.h
+++ b/include/linux/signal.h
@@ -44,7 +44,7 @@ enum siginfo_layout {
 	SIL_FAULT_MCEERR,
 	SIL_FAULT_BNDERR,
 	SIL_FAULT_PKUERR,
-	SIL_PERF_EVENT,
+	SIL_FAULT_PERF_EVENT,
 	SIL_CHLD,
 	SIL_RT,
 	SIL_SYS,
diff --git a/kernel/signal.c b/kernel/signal.c
index 0517ff950d38..690921960d8b 100644
--- a/kernel/signal.c
+++ b/kernel/signal.c
@@ -1198,7 +1198,7 @@ static inline bool has_si_pid_and_uid(struct kernel_siginfo *info)
 	case SIL_FAULT_MCEERR:
 	case SIL_FAULT_BNDERR:
 	case SIL_FAULT_PKUERR:
-	case SIL_PERF_EVENT:
+	case SIL_FAULT_PERF_EVENT:
 	case SIL_SYS:
 		ret = false;
 		break;
@@ -2553,7 +2553,7 @@ static void hide_si_addr_tag_bits(struct ksignal *ksig)
 	case SIL_FAULT_MCEERR:
 	case SIL_FAULT_BNDERR:
 	case SIL_FAULT_PKUERR:
-	case SIL_PERF_EVENT:
+	case SIL_FAULT_PERF_EVENT:
 		ksig->info.si_addr = arch_untagged_si_addr(
 			ksig->info.si_addr, ksig->sig, ksig->info.si_code);
 		break;
@@ -3242,7 +3242,7 @@ enum siginfo_layout siginfo_layout(unsigned sig, int si_code)
 				layout = SIL_FAULT_PKUERR;
 #endif
 			else if ((sig == SIGTRAP) && (si_code == TRAP_PERF))
-				layout = SIL_PERF_EVENT;
+				layout = SIL_FAULT_PERF_EVENT;
 		}
 		else if (si_code <= NSIGPOLL)
 			layout = SIL_POLL;
@@ -3364,7 +3364,7 @@ void copy_siginfo_to_external32(struct compat_siginfo *to,
 		to->si_addr = ptr_to_compat(from->si_addr);
 		to->si_pkey = from->si_pkey;
 		break;
-	case SIL_PERF_EVENT:
+	case SIL_FAULT_PERF_EVENT:
 		to->si_addr = ptr_to_compat(from->si_addr);
 		to->si_perf = from->si_perf;
 		break;
@@ -3440,7 +3440,7 @@ static int post_copy_siginfo_from_user32(kernel_siginfo_t *to,
 		to->si_addr = compat_ptr(from->si_addr);
 		to->si_pkey = from->si_pkey;
 		break;
-	case SIL_PERF_EVENT:
+	case SIL_FAULT_PERF_EVENT:
 		to->si_addr = compat_ptr(from->si_addr);
 		to->si_perf = from->si_perf;
 		break;
-- 
2.30.1

Re: [PATCH 5/3] signal: Rename SIL_PERF_EVENT SIL_FAULT_PERF_EVENT for consistency

[Marco Elver]

On Sat, 1 May 2021 at 01:43, Eric W. Biederman <ebiederm@xmission.com> wrote:
>
> It helps to know which part of the siginfo structure the siginfo_layout
> value is talking about.

Your Signed-off-by seems to be missing.

Otherwise,

Acked-by: Marco Elver <elver@google.com>


> ---
>  fs/signalfd.c          |  2 +-
>  include/linux/signal.h |  2 +-
>  kernel/signal.c        | 10 +++++-----
>  3 files changed, 7 insertions(+), 7 deletions(-)
>
> diff --git a/fs/signalfd.c b/fs/signalfd.c
> index e87e59581653..83130244f653 100644
> --- a/fs/signalfd.c
> +++ b/fs/signalfd.c
> @@ -132,7 +132,7 @@ static int signalfd_copyinfo(struct signalfd_siginfo __user *uinfo,
>                 new.ssi_addr = (long) kinfo->si_addr;
>                 new.ssi_addr_lsb = (short) kinfo->si_addr_lsb;
>                 break;
> -       case SIL_PERF_EVENT:
> +       case SIL_FAULT_PERF_EVENT:
>                 new.ssi_addr = (long) kinfo->si_addr;
>                 new.ssi_perf = kinfo->si_perf;
>                 break;
> diff --git a/include/linux/signal.h b/include/linux/signal.h
> index 5160fd45e5ca..ed896d790e46 100644
> --- a/include/linux/signal.h
> +++ b/include/linux/signal.h
> @@ -44,7 +44,7 @@ enum siginfo_layout {
>         SIL_FAULT_MCEERR,
>         SIL_FAULT_BNDERR,
>         SIL_FAULT_PKUERR,
> -       SIL_PERF_EVENT,
> +       SIL_FAULT_PERF_EVENT,
>         SIL_CHLD,
>         SIL_RT,
>         SIL_SYS,
> diff --git a/kernel/signal.c b/kernel/signal.c
> index 0517ff950d38..690921960d8b 100644
> --- a/kernel/signal.c
> +++ b/kernel/signal.c
> @@ -1198,7 +1198,7 @@ static inline bool has_si_pid_and_uid(struct kernel_siginfo *info)
>         case SIL_FAULT_MCEERR:
>         case SIL_FAULT_BNDERR:
>         case SIL_FAULT_PKUERR:
> -       case SIL_PERF_EVENT:
> +       case SIL_FAULT_PERF_EVENT:
>         case SIL_SYS:
>                 ret = false;
>                 break;
> @@ -2553,7 +2553,7 @@ static void hide_si_addr_tag_bits(struct ksignal *ksig)
>         case SIL_FAULT_MCEERR:
>         case SIL_FAULT_BNDERR:
>         case SIL_FAULT_PKUERR:
> -       case SIL_PERF_EVENT:
> +       case SIL_FAULT_PERF_EVENT:
>                 ksig->info.si_addr = arch_untagged_si_addr(
>                         ksig->info.si_addr, ksig->sig, ksig->info.si_code);
>                 break;
> @@ -3242,7 +3242,7 @@ enum siginfo_layout siginfo_layout(unsigned sig, int si_code)
>                                 layout = SIL_FAULT_PKUERR;
>  #endif
>                         else if ((sig == SIGTRAP) && (si_code == TRAP_PERF))
> -                               layout = SIL_PERF_EVENT;
> +                               layout = SIL_FAULT_PERF_EVENT;
>                 }
>                 else if (si_code <= NSIGPOLL)
>                         layout = SIL_POLL;
> @@ -3364,7 +3364,7 @@ void copy_siginfo_to_external32(struct compat_siginfo *to,
>                 to->si_addr = ptr_to_compat(from->si_addr);
>                 to->si_pkey = from->si_pkey;
>                 break;
> -       case SIL_PERF_EVENT:
> +       case SIL_FAULT_PERF_EVENT:
>                 to->si_addr = ptr_to_compat(from->si_addr);
>                 to->si_perf = from->si_perf;
>                 break;
> @@ -3440,7 +3440,7 @@ static int post_copy_siginfo_from_user32(kernel_siginfo_t *to,
>                 to->si_addr = compat_ptr(from->si_addr);
>                 to->si_pkey = from->si_pkey;
>                 break;
> -       case SIL_PERF_EVENT:
> +       case SIL_FAULT_PERF_EVENT:
>                 to->si_addr = compat_ptr(from->si_addr);
>                 to->si_perf = from->si_perf;
>                 break;
> --
> 2.30.1
>

[PATCH 6/3] signal: Factor force_sig_perf out of perf_sigtrap

[Eric W. Biederman]

Separate generating the signal from deciding it needs to be sent.

Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
---
 include/linux/sched/signal.h |  1 +
 kernel/events/core.c         | 11 ++---------
 kernel/signal.c              | 13 +++++++++++++
 3 files changed, 16 insertions(+), 9 deletions(-)

diff --git a/include/linux/sched/signal.h b/include/linux/sched/signal.h
index 7daa425f3055..1e2f61a1a512 100644
--- a/include/linux/sched/signal.h
+++ b/include/linux/sched/signal.h
@@ -318,6 +318,7 @@ int send_sig_mceerr(int code, void __user *, short, struct task_struct *);
 
 int force_sig_bnderr(void __user *addr, void __user *lower, void __user *upper);
 int force_sig_pkuerr(void __user *addr, u32 pkey);
+int force_sig_perf(void __user *addr, u32 type, u64 sig_data);
 
 int force_sig_fault_trapno(int sig, int code, void __user *addr, int trapno);
 int send_sig_fault_trapno(int sig, int code, void __user *addr, int trapno,
diff --git a/kernel/events/core.c b/kernel/events/core.c
index 928b166d888e..48ea8863183b 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -6394,8 +6394,6 @@ void perf_event_wakeup(struct perf_event *event)
 
 static void perf_sigtrap(struct perf_event *event)
 {
-	struct kernel_siginfo info;
-
 	/*
 	 * We'd expect this to only occur if the irq_work is delayed and either
 	 * ctx->task or current has changed in the meantime. This can be the
@@ -6410,13 +6408,8 @@ static void perf_sigtrap(struct perf_event *event)
 	if (current->flags & PF_EXITING)
 		return;
 
-	clear_siginfo(&info);
-	info.si_signo = SIGTRAP;
-	info.si_code = TRAP_PERF;
-	info.si_errno = event->attr.type;
-	info.si_perf = event->attr.sig_data;
-	info.si_addr = (void __user *)event->pending_addr;
-	force_sig_info(&info);
+	force_sig_perf((void __user *)event->pending_addr,
+		       event->attr.type, event->attr.sig_data);
 }
 
 static void perf_pending_event_disable(struct perf_event *event)
diff --git a/kernel/signal.c b/kernel/signal.c
index 690921960d8b..5b1ad7f080ab 100644
--- a/kernel/signal.c
+++ b/kernel/signal.c
@@ -1753,6 +1753,19 @@ int force_sig_pkuerr(void __user *addr, u32 pkey)
 }
 #endif
 
+int force_sig_perf(void __user *pending_addr, u32 type, u64 sig_data)
+{
+	struct kernel_siginfo info;
+
+	clear_siginfo(&info);
+	info.si_signo = SIGTRAP;
+	info.si_errno = type;
+	info.si_code  = TRAP_PERF;
+	info.si_addr  = pending_addr;
+	info.si_perf  = sig_data;
+	return force_sig_info(&info);
+}
+
 #if IS_ENABLED(SPARC)
 int force_sig_fault_trapno(int sig, int code, void __user *addr, int trapno)
 {
-- 
2.30.1

Re: [PATCH 6/3] signal: Factor force_sig_perf out of perf_sigtrap

[Marco Elver]

On Sat, 1 May 2021 at 01:43, Eric W. Biederman <ebiederm@xmission.com> wrote:
>
> Separate generating the signal from deciding it needs to be sent.
>
> Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
> ---
>  include/linux/sched/signal.h |  1 +
>  kernel/events/core.c         | 11 ++---------
>  kernel/signal.c              | 13 +++++++++++++
>  3 files changed, 16 insertions(+), 9 deletions(-)
>
> diff --git a/include/linux/sched/signal.h b/include/linux/sched/signal.h
> index 7daa425f3055..1e2f61a1a512 100644
> --- a/include/linux/sched/signal.h
> +++ b/include/linux/sched/signal.h
> @@ -318,6 +318,7 @@ int send_sig_mceerr(int code, void __user *, short, struct task_struct *);
>
>  int force_sig_bnderr(void __user *addr, void __user *lower, void __user *upper);
>  int force_sig_pkuerr(void __user *addr, u32 pkey);
> +int force_sig_perf(void __user *addr, u32 type, u64 sig_data);
>
>  int force_sig_fault_trapno(int sig, int code, void __user *addr, int trapno);
>  int send_sig_fault_trapno(int sig, int code, void __user *addr, int trapno,
> diff --git a/kernel/events/core.c b/kernel/events/core.c
> index 928b166d888e..48ea8863183b 100644
> --- a/kernel/events/core.c
> +++ b/kernel/events/core.c
> @@ -6394,8 +6394,6 @@ void perf_event_wakeup(struct perf_event *event)
>
>  static void perf_sigtrap(struct perf_event *event)
>  {
> -       struct kernel_siginfo info;
> -
>         /*
>          * We'd expect this to only occur if the irq_work is delayed and either
>          * ctx->task or current has changed in the meantime. This can be the
> @@ -6410,13 +6408,8 @@ static void perf_sigtrap(struct perf_event *event)
>         if (current->flags & PF_EXITING)
>                 return;
>
> -       clear_siginfo(&info);
> -       info.si_signo = SIGTRAP;
> -       info.si_code = TRAP_PERF;
> -       info.si_errno = event->attr.type;
> -       info.si_perf = event->attr.sig_data;
> -       info.si_addr = (void __user *)event->pending_addr;
> -       force_sig_info(&info);
> +       force_sig_perf((void __user *)event->pending_addr,
> +                      event->attr.type, event->attr.sig_data);
>  }
>
>  static void perf_pending_event_disable(struct perf_event *event)
> diff --git a/kernel/signal.c b/kernel/signal.c
> index 690921960d8b..5b1ad7f080ab 100644
> --- a/kernel/signal.c
> +++ b/kernel/signal.c
> @@ -1753,6 +1753,19 @@ int force_sig_pkuerr(void __user *addr, u32 pkey)
>  }
>  #endif
>
> +int force_sig_perf(void __user *pending_addr, u32 type, u64 sig_data)

s/pending_addr/addr/

to match force_sig_perf() declaration.

> +{
> +       struct kernel_siginfo info;
> +
> +       clear_siginfo(&info);
> +       info.si_signo = SIGTRAP;
> +       info.si_errno = type;
> +       info.si_code  = TRAP_PERF;
> +       info.si_addr  = pending_addr;
> +       info.si_perf  = sig_data;
> +       return force_sig_info(&info);
> +}
> +
>  #if IS_ENABLED(SPARC)
>  int force_sig_fault_trapno(int sig, int code, void __user *addr, int trapno)
>  {
> --
> 2.30.1

[PATCH 7/3] signal: Deliver all of the perf_data in si_perf

[Eric W. Biederman]

Don't abuse si_errno and deliver all of the perf data in si_perf.

Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
---
 fs/signalfd.c                      |  3 ++-
 include/linux/compat.h             |  5 ++++-
 include/uapi/asm-generic/siginfo.h |  5 ++++-
 include/uapi/linux/signalfd.h      |  4 ++--
 kernel/signal.c                    | 18 +++++++++++-------
 5 files changed, 23 insertions(+), 12 deletions(-)

diff --git a/fs/signalfd.c b/fs/signalfd.c
index 83130244f653..9686af56f073 100644
--- a/fs/signalfd.c
+++ b/fs/signalfd.c
@@ -134,7 +134,8 @@ static int signalfd_copyinfo(struct signalfd_siginfo __user *uinfo,
 		break;
 	case SIL_FAULT_PERF_EVENT:
 		new.ssi_addr = (long) kinfo->si_addr;
-		new.ssi_perf = kinfo->si_perf;
+		new.ssi_perf_type = kinfo->si_perf.type;
+		new.ssi_perf_data = kinfo->si_perf.data;
 		break;
 	case SIL_CHLD:
 		new.ssi_pid    = kinfo->si_pid;
diff --git a/include/linux/compat.h b/include/linux/compat.h
index 24462ed63af4..0726f9b3a57c 100644
--- a/include/linux/compat.h
+++ b/include/linux/compat.h
@@ -235,7 +235,10 @@ typedef struct compat_siginfo {
 					u32 _pkey;
 				} _addr_pkey;
 				/* used when si_code=TRAP_PERF */
-				compat_ulong_t _perf;
+				struct {
+					compat_ulong_t data;
+					u32 type;
+				} _perf;
 			};
 		} _sigfault;
 
diff --git a/include/uapi/asm-generic/siginfo.h b/include/uapi/asm-generic/siginfo.h
index 2abdf1d19aad..19b6310021a3 100644
--- a/include/uapi/asm-generic/siginfo.h
+++ b/include/uapi/asm-generic/siginfo.h
@@ -90,7 +90,10 @@ union __sifields {
 				__u32 _pkey;
 			} _addr_pkey;
 			/* used when si_code=TRAP_PERF */
-			unsigned long _perf;
+			struct {
+				unsigned long data;
+				u32 type;
+			} _perf;
 		};
 	} _sigfault;
 
diff --git a/include/uapi/linux/signalfd.h b/include/uapi/linux/signalfd.h
index 7e333042c7e3..e78dddf433fc 100644
--- a/include/uapi/linux/signalfd.h
+++ b/include/uapi/linux/signalfd.h
@@ -39,8 +39,8 @@ struct signalfd_siginfo {
 	__s32 ssi_syscall;
 	__u64 ssi_call_addr;
 	__u32 ssi_arch;
-	__u32 __pad3;
-	__u64 ssi_perf;
+	__u32 ssi_perf_type;
+	__u64 ssi_perf_data;
 
 	/*
 	 * Pad strcture to 128 bytes. Remember to update the
diff --git a/kernel/signal.c b/kernel/signal.c
index 5b1ad7f080ab..cb3574b7319c 100644
--- a/kernel/signal.c
+++ b/kernel/signal.c
@@ -1758,11 +1758,13 @@ int force_sig_perf(void __user *pending_addr, u32 type, u64 sig_data)
 	struct kernel_siginfo info;
 
 	clear_siginfo(&info);
-	info.si_signo = SIGTRAP;
-	info.si_errno = type;
-	info.si_code  = TRAP_PERF;
-	info.si_addr  = pending_addr;
-	info.si_perf  = sig_data;
+	info.si_signo     = SIGTRAP;
+	info.si_errno     = 0;
+	info.si_code      = TRAP_PERF;
+	info.si_addr      = pending_addr;
+	info.si_perf.data = sig_data;
+	info.si_perf.type = type;
+
 	return force_sig_info(&info);
 }
 
@@ -3379,7 +3381,8 @@ void copy_siginfo_to_external32(struct compat_siginfo *to,
 		break;
 	case SIL_FAULT_PERF_EVENT:
 		to->si_addr = ptr_to_compat(from->si_addr);
-		to->si_perf = from->si_perf;
+		to->si_perf.data = from->si_perf.data;
+		to->si_perf.type = from->si_perf.type;
 		break;
 	case SIL_CHLD:
 		to->si_pid = from->si_pid;
@@ -3455,7 +3458,8 @@ static int post_copy_siginfo_from_user32(kernel_siginfo_t *to,
 		break;
 	case SIL_FAULT_PERF_EVENT:
 		to->si_addr = compat_ptr(from->si_addr);
-		to->si_perf = from->si_perf;
+		to->si_perf.data = from->si_perf.data;
+		to->si_perf.type = from->si_perf.type;
 		break;
 	case SIL_CHLD:
 		to->si_pid    = from->si_pid;
-- 
2.30.1

Re: [PATCH 7/3] signal: Deliver all of the perf_data in si_perf

[Marco Elver]

On Sat, 1 May 2021 at 01:44, Eric W. Biederman <ebiederm@xmission.com> wrote:
>
> Don't abuse si_errno and deliver all of the perf data in si_perf.
>
> Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
> ---

Thank you for the fix, this looks cleaner.

Just note that this patch needs to include updates to
tools/testing/selftests/perf_events. This should do it:
>  sed -i 's/si_perf/si_perf.data/g; s/si_errno/si_perf.type/g' tools/testing/selftests/perf_events/*.c

Subject: s/perf_data/perf data/ ?

For uapi, need to switch to __u32, see below.

>  fs/signalfd.c                      |  3 ++-
>  include/linux/compat.h             |  5 ++++-
>  include/uapi/asm-generic/siginfo.h |  5 ++++-
>  include/uapi/linux/signalfd.h      |  4 ++--
>  kernel/signal.c                    | 18 +++++++++++-------
>  5 files changed, 23 insertions(+), 12 deletions(-)
>
> diff --git a/fs/signalfd.c b/fs/signalfd.c
> index 83130244f653..9686af56f073 100644
> --- a/fs/signalfd.c
> +++ b/fs/signalfd.c
> @@ -134,7 +134,8 @@ static int signalfd_copyinfo(struct signalfd_siginfo __user *uinfo,
>                 break;
>         case SIL_FAULT_PERF_EVENT:
>                 new.ssi_addr = (long) kinfo->si_addr;
> -               new.ssi_perf = kinfo->si_perf;
> +               new.ssi_perf_type = kinfo->si_perf.type;
> +               new.ssi_perf_data = kinfo->si_perf.data;
>                 break;
>         case SIL_CHLD:
>                 new.ssi_pid    = kinfo->si_pid;
> diff --git a/include/linux/compat.h b/include/linux/compat.h
> index 24462ed63af4..0726f9b3a57c 100644
> --- a/include/linux/compat.h
> +++ b/include/linux/compat.h
> @@ -235,7 +235,10 @@ typedef struct compat_siginfo {
>                                         u32 _pkey;
>                                 } _addr_pkey;
>                                 /* used when si_code=TRAP_PERF */
> -                               compat_ulong_t _perf;
> +                               struct {
> +                                       compat_ulong_t data;
> +                                       u32 type;
> +                               } _perf;
>                         };
>                 } _sigfault;
>
> diff --git a/include/uapi/asm-generic/siginfo.h b/include/uapi/asm-generic/siginfo.h
> index 2abdf1d19aad..19b6310021a3 100644
> --- a/include/uapi/asm-generic/siginfo.h
> +++ b/include/uapi/asm-generic/siginfo.h
> @@ -90,7 +90,10 @@ union __sifields {
>                                 __u32 _pkey;
>                         } _addr_pkey;
>                         /* used when si_code=TRAP_PERF */
> -                       unsigned long _perf;
> +                       struct {
> +                               unsigned long data;
> +                               u32 type;

This needs to be __u32.


> +                       } _perf;
>                 };
>         } _sigfault;
>
> diff --git a/include/uapi/linux/signalfd.h b/include/uapi/linux/signalfd.h
> index 7e333042c7e3..e78dddf433fc 100644
> --- a/include/uapi/linux/signalfd.h
> +++ b/include/uapi/linux/signalfd.h
> @@ -39,8 +39,8 @@ struct signalfd_siginfo {
>         __s32 ssi_syscall;
>         __u64 ssi_call_addr;
>         __u32 ssi_arch;
> -       __u32 __pad3;
> -       __u64 ssi_perf;
> +       __u32 ssi_perf_type;
> +       __u64 ssi_perf_data;
>
>         /*
>          * Pad strcture to 128 bytes. Remember to update the
> diff --git a/kernel/signal.c b/kernel/signal.c
> index 5b1ad7f080ab..cb3574b7319c 100644
> --- a/kernel/signal.c
> +++ b/kernel/signal.c
> @@ -1758,11 +1758,13 @@ int force_sig_perf(void __user *pending_addr, u32 type, u64 sig_data)
>         struct kernel_siginfo info;
>
>         clear_siginfo(&info);
> -       info.si_signo = SIGTRAP;
> -       info.si_errno = type;
> -       info.si_code  = TRAP_PERF;
> -       info.si_addr  = pending_addr;
> -       info.si_perf  = sig_data;
> +       info.si_signo     = SIGTRAP;
> +       info.si_errno     = 0;
> +       info.si_code      = TRAP_PERF;
> +       info.si_addr      = pending_addr;
> +       info.si_perf.data = sig_data;
> +       info.si_perf.type = type;
> +
>         return force_sig_info(&info);
>  }
>
> @@ -3379,7 +3381,8 @@ void copy_siginfo_to_external32(struct compat_siginfo *to,
>                 break;
>         case SIL_FAULT_PERF_EVENT:
>                 to->si_addr = ptr_to_compat(from->si_addr);
> -               to->si_perf = from->si_perf;
> +               to->si_perf.data = from->si_perf.data;
> +               to->si_perf.type = from->si_perf.type;
>                 break;
>         case SIL_CHLD:
>                 to->si_pid = from->si_pid;
> @@ -3455,7 +3458,8 @@ static int post_copy_siginfo_from_user32(kernel_siginfo_t *to,
>                 break;
>         case SIL_FAULT_PERF_EVENT:
>                 to->si_addr = compat_ptr(from->si_addr);
> -               to->si_perf = from->si_perf;
> +               to->si_perf.data = from->si_perf.data;
> +               to->si_perf.type = from->si_perf.type;
>                 break;
>         case SIL_CHLD:
>                 to->si_pid    = from->si_pid;
> --
> 2.30.1

Re: [PATCH 7/3] signal: Deliver all of the perf_data in si_perf

[Eric W. Biederman]

Marco Elver <elver@google.com> writes:

> On Sat, 1 May 2021 at 01:44, Eric W. Biederman <ebiederm@xmission.com> wrote:
>>
>> Don't abuse si_errno and deliver all of the perf data in si_perf.
>>
>> Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
>> ---
>
> Thank you for the fix, this looks cleaner.
>
> Just note that this patch needs to include updates to
> tools/testing/selftests/perf_events. This should do it:
>>  sed -i 's/si_perf/si_perf.data/g; s/si_errno/si_perf.type/g' tools/testing/selftests/perf_events/*.c
>
> Subject: s/perf_data/perf data/ ?
>
> For uapi, need to switch to __u32, see below.

Good point.

The one thing that this doesn't do is give you a 64bit field
on 32bit architectures.

On 32bit builds the layout is:

	int si_signo;
	int si_errno;
	int si_code;
	void __user *_addr;
        
So I believe if the first 3 fields were moved into the _sifields union
si_perf could define a 64bit field as it's first member and it would not
break anything else.

Given that the data field is 64bit that seems desirable.

Eric


>>  fs/signalfd.c                      |  3 ++-
>>  include/linux/compat.h             |  5 ++++-
>>  include/uapi/asm-generic/siginfo.h |  5 ++++-
>>  include/uapi/linux/signalfd.h      |  4 ++--
>>  kernel/signal.c                    | 18 +++++++++++-------
>>  5 files changed, 23 insertions(+), 12 deletions(-)
>>
>> diff --git a/fs/signalfd.c b/fs/signalfd.c
>> index 83130244f653..9686af56f073 100644
>> --- a/fs/signalfd.c
>> +++ b/fs/signalfd.c
>> @@ -134,7 +134,8 @@ static int signalfd_copyinfo(struct signalfd_siginfo __user *uinfo,
>>                 break;
>>         case SIL_FAULT_PERF_EVENT:
>>                 new.ssi_addr = (long) kinfo->si_addr;
>> -               new.ssi_perf = kinfo->si_perf;
>> +               new.ssi_perf_type = kinfo->si_perf.type;
>> +               new.ssi_perf_data = kinfo->si_perf.data;
>>                 break;
>>         case SIL_CHLD:
>>                 new.ssi_pid    = kinfo->si_pid;
>> diff --git a/include/linux/compat.h b/include/linux/compat.h
>> index 24462ed63af4..0726f9b3a57c 100644
>> --- a/include/linux/compat.h
>> +++ b/include/linux/compat.h
>> @@ -235,7 +235,10 @@ typedef struct compat_siginfo {
>>                                         u32 _pkey;
>>                                 } _addr_pkey;
>>                                 /* used when si_code=TRAP_PERF */
>> -                               compat_ulong_t _perf;
>> +                               struct {
>> +                                       compat_ulong_t data;
>> +                                       u32 type;
>> +                               } _perf;
>>                         };
>>                 } _sigfault;
>>
>> diff --git a/include/uapi/asm-generic/siginfo.h b/include/uapi/asm-generic/siginfo.h
>> index 2abdf1d19aad..19b6310021a3 100644
>> --- a/include/uapi/asm-generic/siginfo.h
>> +++ b/include/uapi/asm-generic/siginfo.h
>> @@ -90,7 +90,10 @@ union __sifields {
>>                                 __u32 _pkey;
>>                         } _addr_pkey;
>>                         /* used when si_code=TRAP_PERF */
>> -                       unsigned long _perf;
>> +                       struct {
>> +                               unsigned long data;
>> +                               u32 type;
>
> This needs to be __u32.
>
>
>> +                       } _perf;
>>                 };
>>         } _sigfault;
>>
>> diff --git a/include/uapi/linux/signalfd.h b/include/uapi/linux/signalfd.h
>> index 7e333042c7e3..e78dddf433fc 100644
>> --- a/include/uapi/linux/signalfd.h
>> +++ b/include/uapi/linux/signalfd.h
>> @@ -39,8 +39,8 @@ struct signalfd_siginfo {
>>         __s32 ssi_syscall;
>>         __u64 ssi_call_addr;
>>         __u32 ssi_arch;
>> -       __u32 __pad3;
>> -       __u64 ssi_perf;
>> +       __u32 ssi_perf_type;
>> +       __u64 ssi_perf_data;
>>
>>         /*
>>          * Pad strcture to 128 bytes. Remember to update the
>> diff --git a/kernel/signal.c b/kernel/signal.c
>> index 5b1ad7f080ab..cb3574b7319c 100644
>> --- a/kernel/signal.c
>> +++ b/kernel/signal.c
>> @@ -1758,11 +1758,13 @@ int force_sig_perf(void __user *pending_addr, u32 type, u64 sig_data)
>>         struct kernel_siginfo info;
>>
>>         clear_siginfo(&info);
>> -       info.si_signo = SIGTRAP;
>> -       info.si_errno = type;
>> -       info.si_code  = TRAP_PERF;
>> -       info.si_addr  = pending_addr;
>> -       info.si_perf  = sig_data;
>> +       info.si_signo     = SIGTRAP;
>> +       info.si_errno     = 0;
>> +       info.si_code      = TRAP_PERF;
>> +       info.si_addr      = pending_addr;
>> +       info.si_perf.data = sig_data;
>> +       info.si_perf.type = type;
>> +
>>         return force_sig_info(&info);
>>  }
>>
>> @@ -3379,7 +3381,8 @@ void copy_siginfo_to_external32(struct compat_siginfo *to,
>>                 break;
>>         case SIL_FAULT_PERF_EVENT:
>>                 to->si_addr = ptr_to_compat(from->si_addr);
>> -               to->si_perf = from->si_perf;
>> +               to->si_perf.data = from->si_perf.data;
>> +               to->si_perf.type = from->si_perf.type;
>>                 break;
>>         case SIL_CHLD:
>>                 to->si_pid = from->si_pid;
>> @@ -3455,7 +3458,8 @@ static int post_copy_siginfo_from_user32(kernel_siginfo_t *to,
>>                 break;
>>         case SIL_FAULT_PERF_EVENT:
>>                 to->si_addr = compat_ptr(from->si_addr);
>> -               to->si_perf = from->si_perf;
>> +               to->si_perf.data = from->si_perf.data;
>> +               to->si_perf.type = from->si_perf.type;
>>                 break;
>>         case SIL_CHLD:
>>                 to->si_pid    = from->si_pid;
>> --
>> 2.30.1

Re: [PATCH 7/3] signal: Deliver all of the perf_data in si_perf

[Marco Elver]

On Sun, 2 May 2021 at 20:39, Eric W. Biederman <ebiederm@xmission.com> wrote:
>
> Marco Elver <elver@google.com> writes:
>
> > On Sat, 1 May 2021 at 01:44, Eric W. Biederman <ebiederm@xmission.com> wrote:
> >>
> >> Don't abuse si_errno and deliver all of the perf data in si_perf.
> >>
> >> Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
> >> ---
> >
> > Thank you for the fix, this looks cleaner.
> >
> > Just note that this patch needs to include updates to
> > tools/testing/selftests/perf_events. This should do it:
> >>  sed -i 's/si_perf/si_perf.data/g; s/si_errno/si_perf.type/g' tools/testing/selftests/perf_events/*.c
> >
> > Subject: s/perf_data/perf data/ ?
> >
> > For uapi, need to switch to __u32, see below.
>
> Good point.
>
> The one thing that this doesn't do is give you a 64bit field
> on 32bit architectures.
>
> On 32bit builds the layout is:
>
>         int si_signo;
>         int si_errno;
>         int si_code;
>         void __user *_addr;
>
> So I believe if the first 3 fields were moved into the _sifields union
> si_perf could define a 64bit field as it's first member and it would not
> break anything else.
>
> Given that the data field is 64bit that seems desirable.

Yes, it's quite unfortunate -- it was __u64 at first, but then we
noticed it broke 32-bit architectures like arm:
https://lore.kernel.org/linux-arch/20210422191823.79012-1-elver@google.com/

Thanks,
-- Marco

Re: [PATCH 7/3] signal: Deliver all of the perf_data in si_perf

[Peter Zijlstra]

On Sun, May 02, 2021 at 01:39:16PM -0500, Eric W. Biederman wrote:

> The one thing that this doesn't do is give you a 64bit field
> on 32bit architectures.
> 
> On 32bit builds the layout is:
> 
> 	int si_signo;
> 	int si_errno;
> 	int si_code;
> 	void __user *_addr;
>         
> So I believe if the first 3 fields were moved into the _sifields union
> si_perf could define a 64bit field as it's first member and it would not
> break anything else.
> 
> Given that the data field is 64bit that seems desirable.

The data field is fundamentally an address, it is internally a u64
because the perf ring buffer has u64 alignment and it saves on compat
crap etc.

So for the 32bit/compat case the high bits will always be 0 and
truncating into an unsigned long is fine.

Re: [PATCH 7/3] signal: Deliver all of the perf_data in si_perf

[Eric W. Biederman]

Peter Zijlstra <peterz@infradead.org> writes:

> On Sun, May 02, 2021 at 01:39:16PM -0500, Eric W. Biederman wrote:
>
>> The one thing that this doesn't do is give you a 64bit field
>> on 32bit architectures.
>> 
>> On 32bit builds the layout is:
>> 
>> 	int si_signo;
>> 	int si_errno;
>> 	int si_code;
>> 	void __user *_addr;
>>         
>> So I believe if the first 3 fields were moved into the _sifields union
>> si_perf could define a 64bit field as it's first member and it would not
>> break anything else.
>> 
>> Given that the data field is 64bit that seems desirable.
>
> The data field is fundamentally an address, it is internally a u64
> because the perf ring buffer has u64 alignment and it saves on compat
> crap etc.
>
> So for the 32bit/compat case the high bits will always be 0 and
> truncating into an unsigned long is fine.

I see why it is fine to truncate the data field into an unsigned long.

Other than technical difficulties in extending siginfo_t is there any
reason not to define data as a __u64?

Eric

Re: [PATCH 7/3] signal: Deliver all of the perf_data in si_perf

[Marco Elver]

On Mon, 3 May 2021 at 21:38, Eric W. Biederman <ebiederm@xmission.com> wrote:
> Peter Zijlstra <peterz@infradead.org> writes:
>
> > On Sun, May 02, 2021 at 01:39:16PM -0500, Eric W. Biederman wrote:
> >
> >> The one thing that this doesn't do is give you a 64bit field
> >> on 32bit architectures.
> >>
> >> On 32bit builds the layout is:
> >>
> >>      int si_signo;
> >>      int si_errno;
> >>      int si_code;
> >>      void __user *_addr;
> >>
> >> So I believe if the first 3 fields were moved into the _sifields union
> >> si_perf could define a 64bit field as it's first member and it would not
> >> break anything else.
> >>
> >> Given that the data field is 64bit that seems desirable.
> >
> > The data field is fundamentally an address, it is internally a u64
> > because the perf ring buffer has u64 alignment and it saves on compat
> > crap etc.
> >
> > So for the 32bit/compat case the high bits will always be 0 and
> > truncating into an unsigned long is fine.
>
> I see why it is fine to truncate the data field into an unsigned long.
>
> Other than technical difficulties in extending siginfo_t is there any
> reason not to define data as a __u64?

No -- like I pointed at earlier, si_perf used to be __u64, but we
can't because of the siginfo_t limitation. What we have now is fine,
and not worth dwelling over given siginfo limitations.

Thanks,
-- Marco

Re: [RFC][PATCH 0/3] signal: Move si_trapno into the _si_fault union

[Eric W. Biederman]

Well with 7 patches instead of 3 that was a little more than I thought
I was going to send.

However that does demonstrate what I am thinking, and I think most of
the changes are reasonable at this point.

I am very curious how synchronous this all is, because if this code
is truly synchronous updating signalfd to handle this class of signal
doesn't really make sense.

If the code is not synchronous using force_sig is questionable.

Eric W. Biederman (7):
      siginfo: Move si_trapno inside the union inside _si_fault
      signal: Implement SIL_FAULT_TRAPNO
      signal: Use dedicated helpers to send signals with si_trapno set
      signal: Remove __ARCH_SI_TRAPNO
      signal: Rename SIL_PERF_EVENT SIL_FAULT_PERF_EVENT for consistency
      signal: Factor force_sig_perf out of perf_sigtrap
      signal: Deliver all of the perf_data in si_perf

 arch/alpha/include/uapi/asm/siginfo.h |   2 -
 arch/alpha/kernel/osf_sys.c           |   2 +-
 arch/alpha/kernel/signal.c            |   4 +-
 arch/alpha/kernel/traps.c             |  24 ++++----
 arch/alpha/mm/fault.c                 |   4 +-
 arch/mips/include/uapi/asm/siginfo.h  |   2 -
 arch/sparc/include/uapi/asm/siginfo.h |   3 -
 arch/sparc/kernel/process_64.c        |   2 +-
 arch/sparc/kernel/sys_sparc_32.c      |   2 +-
 arch/sparc/kernel/sys_sparc_64.c      |   2 +-
 arch/sparc/kernel/traps_32.c          |  22 +++----
 arch/sparc/kernel/traps_64.c          |  44 ++++++--------
 arch/sparc/kernel/unaligned_32.c      |   2 +-
 arch/sparc/mm/fault_32.c              |   2 +-
 arch/sparc/mm/fault_64.c              |   2 +-
 fs/signalfd.c                         |  13 ++--
 include/linux/compat.h                |   9 +--
 include/linux/sched/signal.h          |  13 ++--
 include/linux/signal.h                |   3 +-
 include/uapi/asm-generic/siginfo.h    |  11 ++--
 include/uapi/linux/signalfd.h         |   4 +-
 kernel/events/core.c                  |  11 +---
 kernel/signal.c                       | 108 ++++++++++++++++++++++------------
 23 files changed, 149 insertions(+), 142 deletions(-)

Re: [RFC][PATCH 0/3] signal: Move si_trapno into the _si_fault union

[Marco Elver]

On Sat, 1 May 2021 at 01:48, Eric W. Biederman <ebiederm@xmission.com> wrote:
>
> Well with 7 patches instead of 3 that was a little more than I thought
> I was going to send.
>
> However that does demonstrate what I am thinking, and I think most of
> the changes are reasonable at this point.
>
> I am very curious how synchronous this all is, because if this code
> is truly synchronous updating signalfd to handle this class of signal
> doesn't really make sense.
>
> If the code is not synchronous using force_sig is questionable.
>
> Eric W. Biederman (7):
>       siginfo: Move si_trapno inside the union inside _si_fault
>       signal: Implement SIL_FAULT_TRAPNO
>       signal: Use dedicated helpers to send signals with si_trapno set
>       signal: Remove __ARCH_SI_TRAPNO
>       signal: Rename SIL_PERF_EVENT SIL_FAULT_PERF_EVENT for consistency
>       signal: Factor force_sig_perf out of perf_sigtrap
>       signal: Deliver all of the perf_data in si_perf

Thank you for doing this so quickly -- it looks much cleaner. I'll
have a more detailed look next week and also run some tests myself.

At a first glance, you've broken our tests in
tools/testing/selftests/perf_events/ -- needs a
s/si_perf/si_perf.data/, s/si_errno/si_perf.type/

Thanks!

-- Marco

Re: [RFC][PATCH 0/3] signal: Move si_trapno into the _si_fault union

[Eric W. Biederman]

Marco Elver <elver@google.com> writes:

> On Sat, 1 May 2021 at 01:48, Eric W. Biederman <ebiederm@xmission.com> wrote:
>>
>> Well with 7 patches instead of 3 that was a little more than I thought
>> I was going to send.
>>
>> However that does demonstrate what I am thinking, and I think most of
>> the changes are reasonable at this point.
>>
>> I am very curious how synchronous this all is, because if this code
>> is truly synchronous updating signalfd to handle this class of signal
>> doesn't really make sense.
>>
>> If the code is not synchronous using force_sig is questionable.
>>
>> Eric W. Biederman (7):
>>       siginfo: Move si_trapno inside the union inside _si_fault
>>       signal: Implement SIL_FAULT_TRAPNO
>>       signal: Use dedicated helpers to send signals with si_trapno set
>>       signal: Remove __ARCH_SI_TRAPNO
>>       signal: Rename SIL_PERF_EVENT SIL_FAULT_PERF_EVENT for consistency
>>       signal: Factor force_sig_perf out of perf_sigtrap
>>       signal: Deliver all of the perf_data in si_perf
>
> Thank you for doing this so quickly -- it looks much cleaner. I'll
> have a more detailed look next week and also run some tests myself.
>
> At a first glance, you've broken our tests in
> tools/testing/selftests/perf_events/ -- needs a
> s/si_perf/si_perf.data/, s/si_errno/si_perf.type/

Yeah.  I figured I did, but I couldn't figure out where the tests were
and I didn't have a lot of time.  I just wanted to get this out so we
can do as much as reasonable before the ABI starts being actively used
by userspace and we can't change it.

Eric

Re: [RFC][PATCH 0/3] signal: Move si_trapno into the _si_fault union

[Marco Elver]

On Sat, 1 May 2021 at 17:17, Eric W. Biederman <ebiederm@xmission.com> wrote:
>
> Marco Elver <elver@google.com> writes:
>
> > On Sat, 1 May 2021 at 01:48, Eric W. Biederman <ebiederm@xmission.com> wrote:
> >>
> >> Well with 7 patches instead of 3 that was a little more than I thought
> >> I was going to send.
> >>
> >> However that does demonstrate what I am thinking, and I think most of
> >> the changes are reasonable at this point.
> >>
> >> I am very curious how synchronous this all is, because if this code
> >> is truly synchronous updating signalfd to handle this class of signal
> >> doesn't really make sense.
> >>
> >> If the code is not synchronous using force_sig is questionable.
> >>
> >> Eric W. Biederman (7):
> >>       siginfo: Move si_trapno inside the union inside _si_fault
> >>       signal: Implement SIL_FAULT_TRAPNO
> >>       signal: Use dedicated helpers to send signals with si_trapno set
> >>       signal: Remove __ARCH_SI_TRAPNO
> >>       signal: Rename SIL_PERF_EVENT SIL_FAULT_PERF_EVENT for consistency
> >>       signal: Factor force_sig_perf out of perf_sigtrap
> >>       signal: Deliver all of the perf_data in si_perf
> >
> > Thank you for doing this so quickly -- it looks much cleaner. I'll
> > have a more detailed look next week and also run some tests myself.
> >
> > At a first glance, you've broken our tests in
> > tools/testing/selftests/perf_events/ -- needs a
> > s/si_perf/si_perf.data/, s/si_errno/si_perf.type/
>
> Yeah.  I figured I did, but I couldn't figure out where the tests were
> and I didn't have a lot of time.  I just wanted to get this out so we
> can do as much as reasonable before the ABI starts being actively used
> by userspace and we can't change it.

No worries, and agreed. I've run tools/testing/selftests/perf_events
tests on x86-64 (native + 32-bit compat), and compile-tested x86-32,
arm64, arm (with my static asserts), m68k, and sparc64. Some trivial
breakages, note comments in other patches.

With the trivial fixes this looks good to me. I'll happily retest v2
when you send it.

Thanks,
-- Marco

[PATCH 00/12] signal: sort out si_trapno and si_perf

[Eric W. Biederman]

This is my attempt to sort out the ABI issues with SIGTRAP TRAP_PERF
before any userspace code starts using the new ABI.

The big ideas are:
- Placing the asserts first to prevent unexpected ABI changes
- si_trapno can become an ordinary fault subfield.
- Reworking siginfo so that si_perf_data can be a 64bit field.
- struct signalfd_siginfo is almost full

Marco I have incorporated your static_assert changes and built
on them to prevent having unexpected ABI changes.

The field si_trapno is changed to become an ordinary extension of the
_sigfault member of siginfo.

The code is refactored a bit and then si_perf_data is made a 64bit,
and si_perf_type is made distinct from si_errno.

Finally the signalfd_siginfo fields are removed as they appear to be
filling up the structure without userspace actually being able to use
them.

v1: https://lkml.kernel.org/r/m1zgxfs7zq.fsf_-_@fess.ebiederm.org

Eric W. Biederman (9):
      siginfo: Move si_trapno inside the union inside _si_fault
      signal: Implement SIL_FAULT_TRAPNO
      signal: Use dedicated helpers to send signals with si_trapno set
      signal: Remove __ARCH_SI_TRAPNO
      signal: Rename SIL_PERF_EVENT SIL_FAULT_PERF_EVENT for consistency
      signal: Factor force_sig_perf out of perf_sigtrap
      signal: Redefine signinfo so 64bit fields are possible
      signal: Deliver all of the siginfo perf data in _perf
      signalfd: Remove SIL_FAULT_PERF_EVENT fields from signalfd_siginfo

Marco Elver (3):
      sparc64: Add compile-time asserts for siginfo_t offsets
      arm: Add compile-time asserts for siginfo_t offsets
      arm64: Add compile-time asserts for siginfo_t offsets

 arch/alpha/include/uapi/asm/siginfo.h              |   2 -
 arch/alpha/kernel/osf_sys.c                        |   2 +-
 arch/alpha/kernel/signal.c                         |   4 +-
 arch/alpha/kernel/traps.c                          |  24 ++---
 arch/alpha/mm/fault.c                              |   4 +-
 arch/arm/kernel/signal.c                           |  37 +++++++
 arch/arm64/kernel/signal.c                         |  37 +++++++
 arch/arm64/kernel/signal32.c                       |  37 +++++++
 arch/mips/include/uapi/asm/siginfo.h               |   2 -
 arch/sparc/include/uapi/asm/siginfo.h              |   3 -
 arch/sparc/kernel/process_64.c                     |   2 +-
 arch/sparc/kernel/signal32.c                       |  35 +++++++
 arch/sparc/kernel/signal_64.c                      |  34 +++++++
 arch/sparc/kernel/sys_sparc_32.c                   |   2 +-
 arch/sparc/kernel/sys_sparc_64.c                   |   2 +-
 arch/sparc/kernel/traps_32.c                       |  22 ++--
 arch/sparc/kernel/traps_64.c                       |  44 ++++----
 arch/sparc/kernel/unaligned_32.c                   |   2 +-
 arch/sparc/mm/fault_32.c                           |   2 +-
 arch/sparc/mm/fault_64.c                           |   2 +-
 arch/x86/kernel/signal_compat.c                    |  20 ++--
 fs/signalfd.c                                      |  23 ++---
 include/linux/compat.h                             |  38 ++++---
 include/linux/sched/signal.h                       |  13 +--
 include/linux/signal.h                             |   3 +-
 include/uapi/asm-generic/siginfo.h                 |  57 +++++++----
 include/uapi/linux/signalfd.h                      |   4 +-
 kernel/events/core.c                               |  11 +-
 kernel/signal.c                                    | 113 +++++++++++++--------
 .../selftests/perf_events/sigtrap_threads.c        |  12 +--
 30 files changed, 402 insertions(+), 191 deletions(-)

[PATCH 01/12] sparc64: Add compile-time asserts for siginfo_t offsets

[Eric W. Beiderman]

From: Marco Elver <elver@google.com>

To help catch ABI breaks at compile-time, add compile-time assertions to
verify the siginfo_t layout. Unlike other architectures, sparc64 is
special, because it is one of few architectures requiring si_trapno.
ABI breaks around that field would only be caught here.

Link: https://lkml.kernel.org/r/m11rat9f85.fsf@fess.ebiederm.org
Suggested-by: Eric W. Biederman <ebiederm@xmission.com>
Acked-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Marco Elver <elver@google.com>
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
---
 arch/sparc/kernel/signal32.c  | 34 ++++++++++++++++++++++++++++++++++
 arch/sparc/kernel/signal_64.c | 33 +++++++++++++++++++++++++++++++++
 2 files changed, 67 insertions(+)

diff --git a/arch/sparc/kernel/signal32.c b/arch/sparc/kernel/signal32.c
index e9695a06492f..778ed5c26d4a 100644
--- a/arch/sparc/kernel/signal32.c
+++ b/arch/sparc/kernel/signal32.c
@@ -745,3 +745,37 @@ asmlinkage int do_sys32_sigstack(u32 u_ssptr, u32 u_ossptr, unsigned long sp)
 out:
 	return ret;
 }
+
+/*
+ * Compile-time assertions for siginfo_t offsets. Check NSIG* as well, as
+ * changes likely come with new fields that should be added below.
+ */
+static_assert(NSIGILL	== 11);
+static_assert(NSIGFPE	== 15);
+static_assert(NSIGSEGV	== 9);
+static_assert(NSIGBUS	== 5);
+static_assert(NSIGTRAP	== 6);
+static_assert(NSIGCHLD	== 6);
+static_assert(NSIGSYS	== 2);
+static_assert(offsetof(compat_siginfo_t, si_signo)	== 0x00);
+static_assert(offsetof(compat_siginfo_t, si_errno)	== 0x04);
+static_assert(offsetof(compat_siginfo_t, si_code)	== 0x08);
+static_assert(offsetof(compat_siginfo_t, si_pid)	== 0x0c);
+static_assert(offsetof(compat_siginfo_t, si_uid)	== 0x10);
+static_assert(offsetof(compat_siginfo_t, si_tid)	== 0x0c);
+static_assert(offsetof(compat_siginfo_t, si_overrun)	== 0x10);
+static_assert(offsetof(compat_siginfo_t, si_status)	== 0x14);
+static_assert(offsetof(compat_siginfo_t, si_utime)	== 0x18);
+static_assert(offsetof(compat_siginfo_t, si_stime)	== 0x1c);
+static_assert(offsetof(compat_siginfo_t, si_value)	== 0x14);
+static_assert(offsetof(compat_siginfo_t, si_int)	== 0x14);
+static_assert(offsetof(compat_siginfo_t, si_ptr)	== 0x14);
+static_assert(offsetof(compat_siginfo_t, si_addr)	== 0x0c);
+static_assert(offsetof(compat_siginfo_t, si_trapno)	== 0x10);
+static_assert(offsetof(compat_siginfo_t, si_addr_lsb)	== 0x14);
+static_assert(offsetof(compat_siginfo_t, si_lower)	== 0x18);
+static_assert(offsetof(compat_siginfo_t, si_upper)	== 0x1c);
+static_assert(offsetof(compat_siginfo_t, si_pkey)	== 0x18);
+static_assert(offsetof(compat_siginfo_t, si_perf)	== 0x14);
+static_assert(offsetof(compat_siginfo_t, si_band)	== 0x0c);
+static_assert(offsetof(compat_siginfo_t, si_fd)		== 0x10);
diff --git a/arch/sparc/kernel/signal_64.c b/arch/sparc/kernel/signal_64.c
index a0eec62c825d..c9bbf5f29078 100644
--- a/arch/sparc/kernel/signal_64.c
+++ b/arch/sparc/kernel/signal_64.c
@@ -556,3 +556,36 @@ void do_notify_resume(struct pt_regs *regs, unsigned long orig_i0, unsigned long
 	user_enter();
 }
 
+/*
+ * Compile-time assertions for siginfo_t offsets. Check NSIG* as well, as
+ * changes likely come with new fields that should be added below.
+ */
+static_assert(NSIGILL	== 11);
+static_assert(NSIGFPE	== 15);
+static_assert(NSIGSEGV	== 9);
+static_assert(NSIGBUS	== 5);
+static_assert(NSIGTRAP	== 6);
+static_assert(NSIGCHLD	== 6);
+static_assert(NSIGSYS	== 2);
+static_assert(offsetof(siginfo_t, si_signo)	== 0x00);
+static_assert(offsetof(siginfo_t, si_errno)	== 0x04);
+static_assert(offsetof(siginfo_t, si_code)	== 0x08);
+static_assert(offsetof(siginfo_t, si_pid)	== 0x10);
+static_assert(offsetof(siginfo_t, si_uid)	== 0x14);
+static_assert(offsetof(siginfo_t, si_tid)	== 0x10);
+static_assert(offsetof(siginfo_t, si_overrun)	== 0x14);
+static_assert(offsetof(siginfo_t, si_status)	== 0x18);
+static_assert(offsetof(siginfo_t, si_utime)	== 0x20);
+static_assert(offsetof(siginfo_t, si_stime)	== 0x28);
+static_assert(offsetof(siginfo_t, si_value)	== 0x18);
+static_assert(offsetof(siginfo_t, si_int)	== 0x18);
+static_assert(offsetof(siginfo_t, si_ptr)	== 0x18);
+static_assert(offsetof(siginfo_t, si_addr)	== 0x10);
+static_assert(offsetof(siginfo_t, si_trapno)	== 0x18);
+static_assert(offsetof(siginfo_t, si_addr_lsb)	== 0x20);
+static_assert(offsetof(siginfo_t, si_lower)	== 0x28);
+static_assert(offsetof(siginfo_t, si_upper)	== 0x30);
+static_assert(offsetof(siginfo_t, si_pkey)	== 0x28);
+static_assert(offsetof(siginfo_t, si_perf)	== 0x20);
+static_assert(offsetof(siginfo_t, si_band)	== 0x10);
+static_assert(offsetof(siginfo_t, si_fd)	== 0x14);
-- 
2.30.1

[PATCH 02/12] arm: Add compile-time asserts for siginfo_t offsets

[Eric W. Beiderman]

From: Marco Elver <elver@google.com>

To help catch ABI breaks at compile-time, add compile-time assertions to
verify the siginfo_t layout.

This could have caught that we cannot portably add 64-bit integers to
siginfo_t on 32-bit architectures like Arm before reaching -next:
https://lkml.kernel.org/r/20210422191823.79012-1-elver@google.com

Signed-off-by: Marco Elver <elver@google.com>
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
---
 arch/arm/kernel/signal.c | 36 ++++++++++++++++++++++++++++++++++++
 1 file changed, 36 insertions(+)

diff --git a/arch/arm/kernel/signal.c b/arch/arm/kernel/signal.c
index a3a38d0a4c85..2dac5d2c5cf6 100644
--- a/arch/arm/kernel/signal.c
+++ b/arch/arm/kernel/signal.c
@@ -725,3 +725,39 @@ asmlinkage void do_rseq_syscall(struct pt_regs *regs)
 	rseq_syscall(regs);
 }
 #endif
+
+/*
+ * Compile-time assertions for siginfo_t offsets. Check NSIG* as well, as
+ * changes likely come with new fields that should be added below.
+ */
+static_assert(NSIGILL	== 11);
+static_assert(NSIGFPE	== 15);
+static_assert(NSIGSEGV	== 9);
+static_assert(NSIGBUS	== 5);
+static_assert(NSIGTRAP	== 6);
+static_assert(NSIGCHLD	== 6);
+static_assert(NSIGSYS	== 2);
+static_assert(offsetof(siginfo_t, si_signo)	== 0x00);
+static_assert(offsetof(siginfo_t, si_errno)	== 0x04);
+static_assert(offsetof(siginfo_t, si_code)	== 0x08);
+static_assert(offsetof(siginfo_t, si_pid)	== 0x0c);
+static_assert(offsetof(siginfo_t, si_uid)	== 0x10);
+static_assert(offsetof(siginfo_t, si_tid)	== 0x0c);
+static_assert(offsetof(siginfo_t, si_overrun)	== 0x10);
+static_assert(offsetof(siginfo_t, si_status)	== 0x14);
+static_assert(offsetof(siginfo_t, si_utime)	== 0x18);
+static_assert(offsetof(siginfo_t, si_stime)	== 0x1c);
+static_assert(offsetof(siginfo_t, si_value)	== 0x14);
+static_assert(offsetof(siginfo_t, si_int)	== 0x14);
+static_assert(offsetof(siginfo_t, si_ptr)	== 0x14);
+static_assert(offsetof(siginfo_t, si_addr)	== 0x0c);
+static_assert(offsetof(siginfo_t, si_addr_lsb)	== 0x10);
+static_assert(offsetof(siginfo_t, si_lower)	== 0x14);
+static_assert(offsetof(siginfo_t, si_upper)	== 0x18);
+static_assert(offsetof(siginfo_t, si_pkey)	== 0x14);
+static_assert(offsetof(siginfo_t, si_perf)	== 0x10);
+static_assert(offsetof(siginfo_t, si_band)	== 0x0c);
+static_assert(offsetof(siginfo_t, si_fd)	== 0x10);
+static_assert(offsetof(siginfo_t, si_call_addr)	== 0x0c);
+static_assert(offsetof(siginfo_t, si_syscall)	== 0x10);
+static_assert(offsetof(siginfo_t, si_arch)	== 0x14);
-- 
2.30.1

[PATCH 03/12] arm64: Add compile-time asserts for siginfo_t offsets

[Eric W. Beiderman]

From: Marco Elver <elver@google.com>

To help catch ABI breaks at compile-time, add compile-time assertions to
verify the siginfo_t layout.

Signed-off-by: Marco Elver <elver@google.com>
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
---
 arch/arm64/kernel/signal.c   | 36 ++++++++++++++++++++++++++++++++++++
 arch/arm64/kernel/signal32.c | 36 ++++++++++++++++++++++++++++++++++++
 2 files changed, 72 insertions(+)

diff --git a/arch/arm64/kernel/signal.c b/arch/arm64/kernel/signal.c
index 6237486ff6bb..af8bd2af1298 100644
--- a/arch/arm64/kernel/signal.c
+++ b/arch/arm64/kernel/signal.c
@@ -973,3 +973,39 @@ void __init minsigstksz_setup(void)
 		round_up(sizeof(struct frame_record), 16) +
 		16; /* max alignment padding */
 }
+
+/*
+ * Compile-time assertions for siginfo_t offsets. Check NSIG* as well, as
+ * changes likely come with new fields that should be added below.
+ */
+static_assert(NSIGILL	== 11);
+static_assert(NSIGFPE	== 15);
+static_assert(NSIGSEGV	== 9);
+static_assert(NSIGBUS	== 5);
+static_assert(NSIGTRAP	== 6);
+static_assert(NSIGCHLD	== 6);
+static_assert(NSIGSYS	== 2);
+static_assert(offsetof(siginfo_t, si_signo)	== 0x00);
+static_assert(offsetof(siginfo_t, si_errno)	== 0x04);
+static_assert(offsetof(siginfo_t, si_code)	== 0x08);
+static_assert(offsetof(siginfo_t, si_pid)	== 0x10);
+static_assert(offsetof(siginfo_t, si_uid)	== 0x14);
+static_assert(offsetof(siginfo_t, si_tid)	== 0x10);
+static_assert(offsetof(siginfo_t, si_overrun)	== 0x14);
+static_assert(offsetof(siginfo_t, si_status)	== 0x18);
+static_assert(offsetof(siginfo_t, si_utime)	== 0x20);
+static_assert(offsetof(siginfo_t, si_stime)	== 0x28);
+static_assert(offsetof(siginfo_t, si_value)	== 0x18);
+static_assert(offsetof(siginfo_t, si_int)	== 0x18);
+static_assert(offsetof(siginfo_t, si_ptr)	== 0x18);
+static_assert(offsetof(siginfo_t, si_addr)	== 0x10);
+static_assert(offsetof(siginfo_t, si_addr_lsb)	== 0x18);
+static_assert(offsetof(siginfo_t, si_lower)	== 0x20);
+static_assert(offsetof(siginfo_t, si_upper)	== 0x28);
+static_assert(offsetof(siginfo_t, si_pkey)	== 0x20);
+static_assert(offsetof(siginfo_t, si_perf)	== 0x18);
+static_assert(offsetof(siginfo_t, si_band)	== 0x10);
+static_assert(offsetof(siginfo_t, si_fd)	== 0x18);
+static_assert(offsetof(siginfo_t, si_call_addr)	== 0x10);
+static_assert(offsetof(siginfo_t, si_syscall)	== 0x18);
+static_assert(offsetof(siginfo_t, si_arch)	== 0x1c);
diff --git a/arch/arm64/kernel/signal32.c b/arch/arm64/kernel/signal32.c
index 2f507f565c48..b6afb646515f 100644
--- a/arch/arm64/kernel/signal32.c
+++ b/arch/arm64/kernel/signal32.c
@@ -457,3 +457,39 @@ void compat_setup_restart_syscall(struct pt_regs *regs)
 {
        regs->regs[7] = __NR_compat_restart_syscall;
 }
+
+/*
+ * Compile-time assertions for siginfo_t offsets. Check NSIG* as well, as
+ * changes likely come with new fields that should be added below.
+ */
+static_assert(NSIGILL	== 11);
+static_assert(NSIGFPE	== 15);
+static_assert(NSIGSEGV	== 9);
+static_assert(NSIGBUS	== 5);
+static_assert(NSIGTRAP	== 6);
+static_assert(NSIGCHLD	== 6);
+static_assert(NSIGSYS	== 2);
+static_assert(offsetof(compat_siginfo_t, si_signo)	== 0x00);
+static_assert(offsetof(compat_siginfo_t, si_errno)	== 0x04);
+static_assert(offsetof(compat_siginfo_t, si_code)	== 0x08);
+static_assert(offsetof(compat_siginfo_t, si_pid)	== 0x0c);
+static_assert(offsetof(compat_siginfo_t, si_uid)	== 0x10);
+static_assert(offsetof(compat_siginfo_t, si_tid)	== 0x0c);
+static_assert(offsetof(compat_siginfo_t, si_overrun)	== 0x10);
+static_assert(offsetof(compat_siginfo_t, si_status)	== 0x14);
+static_assert(offsetof(compat_siginfo_t, si_utime)	== 0x18);
+static_assert(offsetof(compat_siginfo_t, si_stime)	== 0x1c);
+static_assert(offsetof(compat_siginfo_t, si_value)	== 0x14);
+static_assert(offsetof(compat_siginfo_t, si_int)	== 0x14);
+static_assert(offsetof(compat_siginfo_t, si_ptr)	== 0x14);
+static_assert(offsetof(compat_siginfo_t, si_addr)	== 0x0c);
+static_assert(offsetof(compat_siginfo_t, si_addr_lsb)	== 0x10);
+static_assert(offsetof(compat_siginfo_t, si_lower)	== 0x14);
+static_assert(offsetof(compat_siginfo_t, si_upper)	== 0x18);
+static_assert(offsetof(compat_siginfo_t, si_pkey)	== 0x14);
+static_assert(offsetof(compat_siginfo_t, si_perf)	== 0x10);
+static_assert(offsetof(compat_siginfo_t, si_band)	== 0x0c);
+static_assert(offsetof(compat_siginfo_t, si_fd)		== 0x10);
+static_assert(offsetof(compat_siginfo_t, si_call_addr)	== 0x0c);
+static_assert(offsetof(compat_siginfo_t, si_syscall)	== 0x10);
+static_assert(offsetof(compat_siginfo_t, si_arch)	== 0x14);
-- 
2.30.1

[PATCH 04/12] siginfo: Move si_trapno inside the union inside _si_fault

[Eric W. Beiderman]

From: "Eric W. Biederman" <ebiederm@xmission.com>

It turns out that linux uses si_trapno very sparingly, and as such it
can be considered extra information for a very narrow selection of
signals, rather than information that is present with every fault
reported in siginfo.

As such move si_trapno inside the union inside of _si_fault.  This
results in no change in placement, and makes it eaiser
to extend _si_fault in the future as this reduces the number of
special cases.  In particular with si_trapno included in the union it
is no longer a concern that the union must be pointer alligned on most
architectures because the union followes immediately after si_addr
which is a pointer.

This change results in a difference in siginfo field placement on
sparc and alpha for the fields si_addr_lsb, si_lower, si_upper,
si_pkey, and si_perf.  These architectures do not implement the
signals that would use si_addr_lsb, si_lower, si_upper, si_pkey, and
si_perf.  Further these architecture have not yet implemented the
userspace that would use si_perf.

The point of this change is in fact to correct these placement issues
before sparc or alpha grow userspace that cares.  This change was
discussed[1] and the agreement is that this change is currently safe.

[1]: https://lkml.kernel.org/r/CAK8P3a0+uKYwL1NhY6Hvtieghba2hKYGD6hcKx5n8=4Gtt+pHA@mail.gmail.com
Acked-by: Marco Elver <elver@google.com>
v1: https://lkml.kernel.org/r/m1tunns7yf.fsf_-_@fess.ebiederm.org
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
---
 arch/sparc/kernel/signal32.c       | 10 +++++-----
 arch/sparc/kernel/signal_64.c      | 10 +++++-----
 arch/x86/kernel/signal_compat.c    |  3 +++
 include/linux/compat.h             |  5 ++---
 include/uapi/asm-generic/siginfo.h |  7 ++-----
 kernel/signal.c                    |  1 +
 6 files changed, 18 insertions(+), 18 deletions(-)

diff --git a/arch/sparc/kernel/signal32.c b/arch/sparc/kernel/signal32.c
index 778ed5c26d4a..73fd8700df3e 100644
--- a/arch/sparc/kernel/signal32.c
+++ b/arch/sparc/kernel/signal32.c
@@ -772,10 +772,10 @@ static_assert(offsetof(compat_siginfo_t, si_int)	== 0x14);
 static_assert(offsetof(compat_siginfo_t, si_ptr)	== 0x14);
 static_assert(offsetof(compat_siginfo_t, si_addr)	== 0x0c);
 static_assert(offsetof(compat_siginfo_t, si_trapno)	== 0x10);
-static_assert(offsetof(compat_siginfo_t, si_addr_lsb)	== 0x14);
-static_assert(offsetof(compat_siginfo_t, si_lower)	== 0x18);
-static_assert(offsetof(compat_siginfo_t, si_upper)	== 0x1c);
-static_assert(offsetof(compat_siginfo_t, si_pkey)	== 0x18);
-static_assert(offsetof(compat_siginfo_t, si_perf)	== 0x14);
+static_assert(offsetof(compat_siginfo_t, si_addr_lsb)	== 0x10);
+static_assert(offsetof(compat_siginfo_t, si_lower)	== 0x14);
+static_assert(offsetof(compat_siginfo_t, si_upper)	== 0x18);
+static_assert(offsetof(compat_siginfo_t, si_pkey)	== 0x14);
+static_assert(offsetof(compat_siginfo_t, si_perf)	== 0x10);
 static_assert(offsetof(compat_siginfo_t, si_band)	== 0x0c);
 static_assert(offsetof(compat_siginfo_t, si_fd)		== 0x10);
diff --git a/arch/sparc/kernel/signal_64.c b/arch/sparc/kernel/signal_64.c
index c9bbf5f29078..17913daa66c6 100644
--- a/arch/sparc/kernel/signal_64.c
+++ b/arch/sparc/kernel/signal_64.c
@@ -582,10 +582,10 @@ static_assert(offsetof(siginfo_t, si_int)	== 0x18);
 static_assert(offsetof(siginfo_t, si_ptr)	== 0x18);
 static_assert(offsetof(siginfo_t, si_addr)	== 0x10);
 static_assert(offsetof(siginfo_t, si_trapno)	== 0x18);
-static_assert(offsetof(siginfo_t, si_addr_lsb)	== 0x20);
-static_assert(offsetof(siginfo_t, si_lower)	== 0x28);
-static_assert(offsetof(siginfo_t, si_upper)	== 0x30);
-static_assert(offsetof(siginfo_t, si_pkey)	== 0x28);
-static_assert(offsetof(siginfo_t, si_perf)	== 0x20);
+static_assert(offsetof(siginfo_t, si_addr_lsb)	== 0x18);
+static_assert(offsetof(siginfo_t, si_lower)	== 0x20);
+static_assert(offsetof(siginfo_t, si_upper)	== 0x28);
+static_assert(offsetof(siginfo_t, si_pkey)	== 0x20);
+static_assert(offsetof(siginfo_t, si_perf)	== 0x18);
 static_assert(offsetof(siginfo_t, si_band)	== 0x10);
 static_assert(offsetof(siginfo_t, si_fd)	== 0x14);
diff --git a/arch/x86/kernel/signal_compat.c b/arch/x86/kernel/signal_compat.c
index 0e5d0a7e203b..a9fcabd8a5e5 100644
--- a/arch/x86/kernel/signal_compat.c
+++ b/arch/x86/kernel/signal_compat.c
@@ -127,6 +127,9 @@ static inline void signal_compat_build_tests(void)
 	BUILD_BUG_ON(offsetof(siginfo_t, si_addr) != 0x10);
 	BUILD_BUG_ON(offsetof(compat_siginfo_t, si_addr) != 0x0C);
 
+	BUILD_BUG_ON(offsetof(siginfo_t, si_trapno) != 0x18);
+	BUILD_BUG_ON(offsetof(compat_siginfo_t, si_trapno) != 0x10);
+
 	BUILD_BUG_ON(offsetof(siginfo_t, si_addr_lsb) != 0x18);
 	BUILD_BUG_ON(offsetof(compat_siginfo_t, si_addr_lsb) != 0x10);
 
diff --git a/include/linux/compat.h b/include/linux/compat.h
index f0d2dd35d408..6af7bef15e94 100644
--- a/include/linux/compat.h
+++ b/include/linux/compat.h
@@ -214,12 +214,11 @@ typedef struct compat_siginfo {
 		/* SIGILL, SIGFPE, SIGSEGV, SIGBUS, SIGTRAP, SIGEMT */
 		struct {
 			compat_uptr_t _addr;	/* faulting insn/memory ref. */
-#ifdef __ARCH_SI_TRAPNO
-			int _trapno;	/* TRAP # which caused the signal */
-#endif
 #define __COMPAT_ADDR_BND_PKEY_PAD  (__alignof__(compat_uptr_t) < sizeof(short) ? \
 				     sizeof(short) : __alignof__(compat_uptr_t))
 			union {
+				/* used on alpha and sparc */
+				int _trapno;	/* TRAP # which caused the signal */
 				/*
 				 * used when si_code=BUS_MCEERR_AR or
 				 * used when si_code=BUS_MCEERR_AO
diff --git a/include/uapi/asm-generic/siginfo.h b/include/uapi/asm-generic/siginfo.h
index 03d6f6d2c1fe..e663bf117b46 100644
--- a/include/uapi/asm-generic/siginfo.h
+++ b/include/uapi/asm-generic/siginfo.h
@@ -63,9 +63,6 @@ union __sifields {
 	/* SIGILL, SIGFPE, SIGSEGV, SIGBUS, SIGTRAP, SIGEMT */
 	struct {
 		void __user *_addr; /* faulting insn/memory ref. */
-#ifdef __ARCH_SI_TRAPNO
-		int _trapno;	/* TRAP # which caused the signal */
-#endif
 #ifdef __ia64__
 		int _imm;		/* immediate value for "break" */
 		unsigned int _flags;	/* see ia64 si_flags */
@@ -75,6 +72,8 @@ union __sifields {
 #define __ADDR_BND_PKEY_PAD  (__alignof__(void *) < sizeof(short) ? \
 			      sizeof(short) : __alignof__(void *))
 		union {
+			/* used on alpha and sparc */
+			int _trapno;	/* TRAP # which caused the signal */
 			/*
 			 * used when si_code=BUS_MCEERR_AR or
 			 * used when si_code=BUS_MCEERR_AO
@@ -150,9 +149,7 @@ typedef struct siginfo {
 #define si_int		_sifields._rt._sigval.sival_int
 #define si_ptr		_sifields._rt._sigval.sival_ptr
 #define si_addr		_sifields._sigfault._addr
-#ifdef __ARCH_SI_TRAPNO
 #define si_trapno	_sifields._sigfault._trapno
-#endif
 #define si_addr_lsb	_sifields._sigfault._addr_lsb
 #define si_lower	_sifields._sigfault._addr_bnd._lower
 #define si_upper	_sifields._sigfault._addr_bnd._upper
diff --git a/kernel/signal.c b/kernel/signal.c
index c3017aa8024a..65888aec65a0 100644
--- a/kernel/signal.c
+++ b/kernel/signal.c
@@ -4607,6 +4607,7 @@ static inline void siginfo_buildtime_checks(void)
 
 	/* sigfault */
 	CHECK_OFFSET(si_addr);
+	CHECK_OFFSET(si_trapno);
 	CHECK_OFFSET(si_addr_lsb);
 	CHECK_OFFSET(si_lower);
 	CHECK_OFFSET(si_upper);
-- 
2.30.1

[PATCH 05/12] signal: Implement SIL_FAULT_TRAPNO

[Eric W. Beiderman]

From: "Eric W. Biederman" <ebiederm@xmission.com>

Now that si_trapno is part of the union in _si_fault and available on
all architectures, add SIL_FAULT_TRAPNO and update siginfo_layout to
return SIL_FAULT_TRAPNO when si_trapno is actually used.

Update the code that uses siginfo_layout to deal with SIL_FAULT_TRAPNO
and have the same code ignore si_trapno in in all other cases.

v1: https://lkml.kernel.org/r/m1o8dvs7s7.fsf_-_@fess.ebiederm.org
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
---
 fs/signalfd.c          |  8 +++-----
 include/linux/signal.h |  1 +
 kernel/signal.c        | 37 +++++++++++++++----------------------
 3 files changed, 19 insertions(+), 27 deletions(-)

diff --git a/fs/signalfd.c b/fs/signalfd.c
index 040a1142915f..e87e59581653 100644
--- a/fs/signalfd.c
+++ b/fs/signalfd.c
@@ -123,15 +123,13 @@ static int signalfd_copyinfo(struct signalfd_siginfo __user *uinfo,
 		 */
 	case SIL_FAULT:
 		new.ssi_addr = (long) kinfo->si_addr;
-#ifdef __ARCH_SI_TRAPNO
+		break;
+	case SIL_FAULT_TRAPNO:
+		new.ssi_addr = (long) kinfo->si_addr;
 		new.ssi_trapno = kinfo->si_trapno;
-#endif
 		break;
 	case SIL_FAULT_MCEERR:
 		new.ssi_addr = (long) kinfo->si_addr;
-#ifdef __ARCH_SI_TRAPNO
-		new.ssi_trapno = kinfo->si_trapno;
-#endif
 		new.ssi_addr_lsb = (short) kinfo->si_addr_lsb;
 		break;
 	case SIL_PERF_EVENT:
diff --git a/include/linux/signal.h b/include/linux/signal.h
index 1e98548d7cf6..5160fd45e5ca 100644
--- a/include/linux/signal.h
+++ b/include/linux/signal.h
@@ -40,6 +40,7 @@ enum siginfo_layout {
 	SIL_TIMER,
 	SIL_POLL,
 	SIL_FAULT,
+	SIL_FAULT_TRAPNO,
 	SIL_FAULT_MCEERR,
 	SIL_FAULT_BNDERR,
 	SIL_FAULT_PKUERR,
diff --git a/kernel/signal.c b/kernel/signal.c
index 65888aec65a0..3d3ba7949788 100644
--- a/kernel/signal.c
+++ b/kernel/signal.c
@@ -1194,6 +1194,7 @@ static inline bool has_si_pid_and_uid(struct kernel_siginfo *info)
 	case SIL_TIMER:
 	case SIL_POLL:
 	case SIL_FAULT:
+	case SIL_FAULT_TRAPNO:
 	case SIL_FAULT_MCEERR:
 	case SIL_FAULT_BNDERR:
 	case SIL_FAULT_PKUERR:
@@ -2527,6 +2528,7 @@ static void hide_si_addr_tag_bits(struct ksignal *ksig)
 {
 	switch (siginfo_layout(ksig->sig, ksig->info.si_code)) {
 	case SIL_FAULT:
+	case SIL_FAULT_TRAPNO:
 	case SIL_FAULT_MCEERR:
 	case SIL_FAULT_BNDERR:
 	case SIL_FAULT_PKUERR:
@@ -3206,6 +3208,13 @@ enum siginfo_layout siginfo_layout(unsigned sig, int si_code)
 			if ((sig == SIGBUS) &&
 			    (si_code >= BUS_MCEERR_AR) && (si_code <= BUS_MCEERR_AO))
 				layout = SIL_FAULT_MCEERR;
+			else if (IS_ENABLED(CONFIG_ALPHA) &&
+				 ((sig == SIGFPE) ||
+				  ((sig == SIGTRAP) && (si_code == TRAP_UNK))))
+				layout = SIL_FAULT_TRAPNO;
+			else if (IS_ENABLED(CONFIG_SPARC) &&
+				 (sig == SIGILL) && (si_code == ILL_ILLTRP))
+				layout = SIL_FAULT_TRAPNO;
 			else if ((sig == SIGSEGV) && (si_code == SEGV_BNDERR))
 				layout = SIL_FAULT_BNDERR;
 #ifdef SEGV_PKUERR
@@ -3317,30 +3326,22 @@ void copy_siginfo_to_external32(struct compat_siginfo *to,
 		break;
 	case SIL_FAULT:
 		to->si_addr = ptr_to_compat(from->si_addr);
-#ifdef __ARCH_SI_TRAPNO
+		break;
+	case SIL_FAULT_TRAPNO:
+		to->si_addr = ptr_to_compat(from->si_addr);
 		to->si_trapno = from->si_trapno;
-#endif
 		break;
 	case SIL_FAULT_MCEERR:
 		to->si_addr = ptr_to_compat(from->si_addr);
-#ifdef __ARCH_SI_TRAPNO
-		to->si_trapno = from->si_trapno;
-#endif
 		to->si_addr_lsb = from->si_addr_lsb;
 		break;
 	case SIL_FAULT_BNDERR:
 		to->si_addr = ptr_to_compat(from->si_addr);
-#ifdef __ARCH_SI_TRAPNO
-		to->si_trapno = from->si_trapno;
-#endif
 		to->si_lower = ptr_to_compat(from->si_lower);
 		to->si_upper = ptr_to_compat(from->si_upper);
 		break;
 	case SIL_FAULT_PKUERR:
 		to->si_addr = ptr_to_compat(from->si_addr);
-#ifdef __ARCH_SI_TRAPNO
-		to->si_trapno = from->si_trapno;
-#endif
 		to->si_pkey = from->si_pkey;
 		break;
 	case SIL_PERF_EVENT:
@@ -3401,30 +3402,22 @@ static int post_copy_siginfo_from_user32(kernel_siginfo_t *to,
 		break;
 	case SIL_FAULT:
 		to->si_addr = compat_ptr(from->si_addr);
-#ifdef __ARCH_SI_TRAPNO
+		break;
+	case SIL_FAULT_TRAPNO:
+		to->si_addr = compat_ptr(from->si_addr);
 		to->si_trapno = from->si_trapno;
-#endif
 		break;
 	case SIL_FAULT_MCEERR:
 		to->si_addr = compat_ptr(from->si_addr);
-#ifdef __ARCH_SI_TRAPNO
-		to->si_trapno = from->si_trapno;
-#endif
 		to->si_addr_lsb = from->si_addr_lsb;
 		break;
 	case SIL_FAULT_BNDERR:
 		to->si_addr = compat_ptr(from->si_addr);
-#ifdef __ARCH_SI_TRAPNO
-		to->si_trapno = from->si_trapno;
-#endif
 		to->si_lower = compat_ptr(from->si_lower);
 		to->si_upper = compat_ptr(from->si_upper);
 		break;
 	case SIL_FAULT_PKUERR:
 		to->si_addr = compat_ptr(from->si_addr);
-#ifdef __ARCH_SI_TRAPNO
-		to->si_trapno = from->si_trapno;
-#endif
 		to->si_pkey = from->si_pkey;
 		break;
 	case SIL_PERF_EVENT:
-- 
2.30.1

[PATCH 06/12] signal: Use dedicated helpers to send signals with si_trapno set

[Eric W. Beiderman]

From: "Eric W. Biederman" <ebiederm@xmission.com>

Now that si_trapno is no longer expected to be present for every fault
reported using siginfo on alpha and sparc remove the trapno parameter
from force_sig_fault, force_sig_fault_to_task and send_sig_fault.

Add two new helpers force_sig_fault_trapno and send_sig_fautl_trapno
for those signals where trapno is expected to be set.

v1: https://lkml.kernel.org/r/m1eeers7q7.fsf_-_@fess.ebiederm.org
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
---
 arch/alpha/kernel/osf_sys.c      |  2 +-
 arch/alpha/kernel/signal.c       |  4 +--
 arch/alpha/kernel/traps.c        | 24 ++++++++---------
 arch/alpha/mm/fault.c            |  4 +--
 arch/sparc/kernel/process_64.c   |  2 +-
 arch/sparc/kernel/sys_sparc_32.c |  2 +-
 arch/sparc/kernel/sys_sparc_64.c |  2 +-
 arch/sparc/kernel/traps_32.c     | 22 ++++++++--------
 arch/sparc/kernel/traps_64.c     | 44 ++++++++++++++------------------
 arch/sparc/kernel/unaligned_32.c |  2 +-
 arch/sparc/mm/fault_32.c         |  2 +-
 arch/sparc/mm/fault_64.c         |  2 +-
 include/linux/sched/signal.h     | 12 +++------
 kernel/signal.c                  | 41 +++++++++++++++++++++--------
 14 files changed, 88 insertions(+), 77 deletions(-)

diff --git a/arch/alpha/kernel/osf_sys.c b/arch/alpha/kernel/osf_sys.c
index d5367a1c6300..80c5d7fbe66a 100644
--- a/arch/alpha/kernel/osf_sys.c
+++ b/arch/alpha/kernel/osf_sys.c
@@ -878,7 +878,7 @@ SYSCALL_DEFINE5(osf_setsysinfo, unsigned long, op, void __user *, buffer,
 
 			send_sig_fault(SIGFPE, si_code,
 				       (void __user *)NULL,  /* FIXME */
-				       0, current);
+				       current);
  		}
 		return 0;
 	}
diff --git a/arch/alpha/kernel/signal.c b/arch/alpha/kernel/signal.c
index 948b89789da8..bc077babafab 100644
--- a/arch/alpha/kernel/signal.c
+++ b/arch/alpha/kernel/signal.c
@@ -219,7 +219,7 @@ do_sigreturn(struct sigcontext __user *sc)
 
 	/* Send SIGTRAP if we're single-stepping: */
 	if (ptrace_cancel_bpt (current)) {
-		send_sig_fault(SIGTRAP, TRAP_BRKPT, (void __user *) regs->pc, 0,
+		send_sig_fault(SIGTRAP, TRAP_BRKPT, (void __user *) regs->pc,
 			       current);
 	}
 	return;
@@ -247,7 +247,7 @@ do_rt_sigreturn(struct rt_sigframe __user *frame)
 
 	/* Send SIGTRAP if we're single-stepping: */
 	if (ptrace_cancel_bpt (current)) {
-		send_sig_fault(SIGTRAP, TRAP_BRKPT, (void __user *) regs->pc, 0,
+		send_sig_fault(SIGTRAP, TRAP_BRKPT, (void __user *) regs->pc,
 			       current);
 	}
 	return;
diff --git a/arch/alpha/kernel/traps.c b/arch/alpha/kernel/traps.c
index 921d4b6e4d95..0dddf9ecc1f4 100644
--- a/arch/alpha/kernel/traps.c
+++ b/arch/alpha/kernel/traps.c
@@ -227,7 +227,7 @@ do_entArith(unsigned long summary, unsigned long write_mask,
 	}
 	die_if_kernel("Arithmetic fault", regs, 0, NULL);
 
-	send_sig_fault(SIGFPE, si_code, (void __user *) regs->pc, 0, current);
+	send_sig_fault_trapno(SIGFPE, si_code, (void __user *) regs->pc, 0, current);
 }
 
 asmlinkage void
@@ -268,12 +268,12 @@ do_entIF(unsigned long type, struct pt_regs *regs)
 			regs->pc -= 4;	/* make pc point to former bpt */
 		}
 
-		send_sig_fault(SIGTRAP, TRAP_BRKPT, (void __user *)regs->pc, 0,
+		send_sig_fault(SIGTRAP, TRAP_BRKPT, (void __user *)regs->pc,
 			       current);
 		return;
 
 	      case 1: /* bugcheck */
-		send_sig_fault(SIGTRAP, TRAP_UNK, (void __user *) regs->pc, 0,
+		send_sig_fault(SIGTRAP, TRAP_UNK, (void __user *) regs->pc,
 			       current);
 		return;
 		
@@ -335,8 +335,8 @@ do_entIF(unsigned long type, struct pt_regs *regs)
 			break;
 		}
 
-		send_sig_fault(signo, code, (void __user *) regs->pc, regs->r16,
-			       current);
+		send_sig_fault_trapno(signo, code, (void __user *) regs->pc,
+				      regs->r16, current);
 		return;
 
 	      case 4: /* opDEC */
@@ -360,9 +360,9 @@ do_entIF(unsigned long type, struct pt_regs *regs)
 			if (si_code == 0)
 				return;
 			if (si_code > 0) {
-				send_sig_fault(SIGFPE, si_code,
-					       (void __user *) regs->pc, 0,
-					       current);
+				send_sig_fault_trapno(SIGFPE, si_code,
+						      (void __user *) regs->pc,
+						      0, current);
 				return;
 			}
 		}
@@ -387,7 +387,7 @@ do_entIF(unsigned long type, struct pt_regs *regs)
 		      ;
 	}
 
-	send_sig_fault(SIGILL, ILL_ILLOPC, (void __user *)regs->pc, 0, current);
+	send_sig_fault(SIGILL, ILL_ILLOPC, (void __user *)regs->pc, current);
 }
 
 /* There is an ifdef in the PALcode in MILO that enables a 
@@ -402,7 +402,7 @@ do_entDbg(struct pt_regs *regs)
 {
 	die_if_kernel("Instruction fault", regs, 0, NULL);
 
-	force_sig_fault(SIGILL, ILL_ILLOPC, (void __user *)regs->pc, 0);
+	force_sig_fault(SIGILL, ILL_ILLOPC, (void __user *)regs->pc);
 }
 
 
@@ -964,12 +964,12 @@ do_entUnaUser(void __user * va, unsigned long opcode,
 			si_code = SEGV_MAPERR;
 		mmap_read_unlock(mm);
 	}
-	send_sig_fault(SIGSEGV, si_code, va, 0, current);
+	send_sig_fault(SIGSEGV, si_code, va, current);
 	return;
 
 give_sigbus:
 	regs->pc -= 4;
-	send_sig_fault(SIGBUS, BUS_ADRALN, va, 0, current);
+	send_sig_fault(SIGBUS, BUS_ADRALN, va, current);
 	return;
 }
 
diff --git a/arch/alpha/mm/fault.c b/arch/alpha/mm/fault.c
index 09172f017efc..eee5102c3d88 100644
--- a/arch/alpha/mm/fault.c
+++ b/arch/alpha/mm/fault.c
@@ -219,13 +219,13 @@ do_page_fault(unsigned long address, unsigned long mmcsr,
 	mmap_read_unlock(mm);
 	/* Send a sigbus, regardless of whether we were in kernel
 	   or user mode.  */
-	force_sig_fault(SIGBUS, BUS_ADRERR, (void __user *) address, 0);
+	force_sig_fault(SIGBUS, BUS_ADRERR, (void __user *) address);
 	if (!user_mode(regs))
 		goto no_context;
 	return;
 
  do_sigsegv:
-	force_sig_fault(SIGSEGV, si_code, (void __user *) address, 0);
+	force_sig_fault(SIGSEGV, si_code, (void __user *) address);
 	return;
 
 #ifdef CONFIG_ALPHA_LARGE_VMALLOC
diff --git a/arch/sparc/kernel/process_64.c b/arch/sparc/kernel/process_64.c
index 7afd0a859a78..29e67854d5a4 100644
--- a/arch/sparc/kernel/process_64.c
+++ b/arch/sparc/kernel/process_64.c
@@ -518,7 +518,7 @@ void synchronize_user_stack(void)
 
 static void stack_unaligned(unsigned long sp)
 {
-	force_sig_fault(SIGBUS, BUS_ADRALN, (void __user *) sp, 0);
+	force_sig_fault(SIGBUS, BUS_ADRALN, (void __user *) sp);
 }
 
 static const char uwfault32[] = KERN_INFO \
diff --git a/arch/sparc/kernel/sys_sparc_32.c b/arch/sparc/kernel/sys_sparc_32.c
index be77538bc038..082a551897ed 100644
--- a/arch/sparc/kernel/sys_sparc_32.c
+++ b/arch/sparc/kernel/sys_sparc_32.c
@@ -151,7 +151,7 @@ sparc_breakpoint (struct pt_regs *regs)
 #ifdef DEBUG_SPARC_BREAKPOINT
         printk ("TRAP: Entering kernel PC=%x, nPC=%x\n", regs->pc, regs->npc);
 #endif
-	force_sig_fault(SIGTRAP, TRAP_BRKPT, (void __user *)regs->pc, 0);
+	force_sig_fault(SIGTRAP, TRAP_BRKPT, (void __user *)regs->pc);
 
 #ifdef DEBUG_SPARC_BREAKPOINT
 	printk ("TRAP: Returning to space: PC=%x nPC=%x\n", regs->pc, regs->npc);
diff --git a/arch/sparc/kernel/sys_sparc_64.c b/arch/sparc/kernel/sys_sparc_64.c
index 6b92fadb6ec7..1e9a9e016237 100644
--- a/arch/sparc/kernel/sys_sparc_64.c
+++ b/arch/sparc/kernel/sys_sparc_64.c
@@ -514,7 +514,7 @@ asmlinkage void sparc_breakpoint(struct pt_regs *regs)
 #ifdef DEBUG_SPARC_BREAKPOINT
         printk ("TRAP: Entering kernel PC=%lx, nPC=%lx\n", regs->tpc, regs->tnpc);
 #endif
-	force_sig_fault(SIGTRAP, TRAP_BRKPT, (void __user *)regs->tpc, 0);
+	force_sig_fault(SIGTRAP, TRAP_BRKPT, (void __user *)regs->tpc);
 #ifdef DEBUG_SPARC_BREAKPOINT
 	printk ("TRAP: Returning to space: PC=%lx nPC=%lx\n", regs->tpc, regs->tnpc);
 #endif
diff --git a/arch/sparc/kernel/traps_32.c b/arch/sparc/kernel/traps_32.c
index 247a0d9683b2..5630e5a395e0 100644
--- a/arch/sparc/kernel/traps_32.c
+++ b/arch/sparc/kernel/traps_32.c
@@ -102,8 +102,8 @@ void do_hw_interrupt(struct pt_regs *regs, unsigned long type)
 	if(regs->psr & PSR_PS)
 		die_if_kernel("Kernel bad trap", regs);
 
-	force_sig_fault(SIGILL, ILL_ILLTRP,
-			(void __user *)regs->pc, type - 0x80);
+	force_sig_fault_trapno(SIGILL, ILL_ILLTRP,
+			       (void __user *)regs->pc, type - 0x80);
 }
 
 void do_illegal_instruction(struct pt_regs *regs, unsigned long pc, unsigned long npc,
@@ -116,7 +116,7 @@ void do_illegal_instruction(struct pt_regs *regs, unsigned long pc, unsigned lon
 	       regs->pc, *(unsigned long *)regs->pc);
 #endif
 
-	send_sig_fault(SIGILL, ILL_ILLOPC, (void __user *)pc, 0, current);
+	send_sig_fault(SIGILL, ILL_ILLOPC, (void __user *)pc, current);
 }
 
 void do_priv_instruction(struct pt_regs *regs, unsigned long pc, unsigned long npc,
@@ -124,7 +124,7 @@ void do_priv_instruction(struct pt_regs *regs, unsigned long pc, unsigned long n
 {
 	if(psr & PSR_PS)
 		die_if_kernel("Penguin instruction from Penguin mode??!?!", regs);
-	send_sig_fault(SIGILL, ILL_PRVOPC, (void __user *)pc, 0, current);
+	send_sig_fault(SIGILL, ILL_PRVOPC, (void __user *)pc, current);
 }
 
 /* XXX User may want to be allowed to do this. XXX */
@@ -145,7 +145,7 @@ void do_memaccess_unaligned(struct pt_regs *regs, unsigned long pc, unsigned lon
 #endif
 	send_sig_fault(SIGBUS, BUS_ADRALN,
 		       /* FIXME: Should dig out mna address */ (void *)0,
-		       0, current);
+		       current);
 }
 
 static unsigned long init_fsr = 0x0UL;
@@ -291,7 +291,7 @@ void do_fpe_trap(struct pt_regs *regs, unsigned long pc, unsigned long npc,
 		else if (fsr & 0x01)
 			code = FPE_FLTRES;
 	}
-	send_sig_fault(SIGFPE, code, (void __user *)pc, 0, fpt);
+	send_sig_fault(SIGFPE, code, (void __user *)pc, fpt);
 #ifndef CONFIG_SMP
 	last_task_used_math = NULL;
 #endif
@@ -305,7 +305,7 @@ void handle_tag_overflow(struct pt_regs *regs, unsigned long pc, unsigned long n
 {
 	if(psr & PSR_PS)
 		die_if_kernel("Penguin overflow trap from kernel mode", regs);
-	send_sig_fault(SIGEMT, EMT_TAGOVF, (void __user *)pc, 0, current);
+	send_sig_fault(SIGEMT, EMT_TAGOVF, (void __user *)pc, current);
 }
 
 void handle_watchpoint(struct pt_regs *regs, unsigned long pc, unsigned long npc,
@@ -327,13 +327,13 @@ void handle_reg_access(struct pt_regs *regs, unsigned long pc, unsigned long npc
 	printk("Register Access Exception at PC %08lx NPC %08lx PSR %08lx\n",
 	       pc, npc, psr);
 #endif
-	force_sig_fault(SIGBUS, BUS_OBJERR, (void __user *)pc, 0);
+	force_sig_fault(SIGBUS, BUS_OBJERR, (void __user *)pc);
 }
 
 void handle_cp_disabled(struct pt_regs *regs, unsigned long pc, unsigned long npc,
 			unsigned long psr)
 {
-	send_sig_fault(SIGILL, ILL_COPROC, (void __user *)pc, 0, current);
+	send_sig_fault(SIGILL, ILL_COPROC, (void __user *)pc, current);
 }
 
 void handle_cp_exception(struct pt_regs *regs, unsigned long pc, unsigned long npc,
@@ -343,13 +343,13 @@ void handle_cp_exception(struct pt_regs *regs, unsigned long pc, unsigned long n
 	printk("Co-Processor Exception at PC %08lx NPC %08lx PSR %08lx\n",
 	       pc, npc, psr);
 #endif
-	send_sig_fault(SIGILL, ILL_COPROC, (void __user *)pc, 0, current);
+	send_sig_fault(SIGILL, ILL_COPROC, (void __user *)pc, current);
 }
 
 void handle_hw_divzero(struct pt_regs *regs, unsigned long pc, unsigned long npc,
 		       unsigned long psr)
 {
-	send_sig_fault(SIGFPE, FPE_INTDIV, (void __user *)pc, 0, current);
+	send_sig_fault(SIGFPE, FPE_INTDIV, (void __user *)pc, current);
 }
 
 #ifdef CONFIG_DEBUG_BUGVERBOSE
diff --git a/arch/sparc/kernel/traps_64.c b/arch/sparc/kernel/traps_64.c
index a850dccd78ea..6863025ed56d 100644
--- a/arch/sparc/kernel/traps_64.c
+++ b/arch/sparc/kernel/traps_64.c
@@ -107,8 +107,8 @@ void bad_trap(struct pt_regs *regs, long lvl)
 		regs->tpc &= 0xffffffff;
 		regs->tnpc &= 0xffffffff;
 	}
-	force_sig_fault(SIGILL, ILL_ILLTRP,
-			(void __user *)regs->tpc, lvl);
+	force_sig_fault_trapno(SIGILL, ILL_ILLTRP,
+			       (void __user *)regs->tpc, lvl);
 }
 
 void bad_trap_tl1(struct pt_regs *regs, long lvl)
@@ -201,8 +201,7 @@ void spitfire_insn_access_exception(struct pt_regs *regs, unsigned long sfsr, un
 		regs->tpc &= 0xffffffff;
 		regs->tnpc &= 0xffffffff;
 	}
-	force_sig_fault(SIGSEGV, SEGV_MAPERR,
-			(void __user *)regs->tpc, 0);
+	force_sig_fault(SIGSEGV, SEGV_MAPERR, (void __user *)regs->tpc);
 out:
 	exception_exit(prev_state);
 }
@@ -237,7 +236,7 @@ void sun4v_insn_access_exception(struct pt_regs *regs, unsigned long addr, unsig
 		regs->tpc &= 0xffffffff;
 		regs->tnpc &= 0xffffffff;
 	}
-	force_sig_fault(SIGSEGV, SEGV_MAPERR, (void __user *) addr, 0);
+	force_sig_fault(SIGSEGV, SEGV_MAPERR, (void __user *) addr);
 }
 
 void sun4v_insn_access_exception_tl1(struct pt_regs *regs, unsigned long addr, unsigned long type_ctx)
@@ -321,7 +320,7 @@ void spitfire_data_access_exception(struct pt_regs *regs, unsigned long sfsr, un
 	if (is_no_fault_exception(regs))
 		return;
 
-	force_sig_fault(SIGSEGV, SEGV_MAPERR, (void __user *)sfar, 0);
+	force_sig_fault(SIGSEGV, SEGV_MAPERR, (void __user *)sfar);
 out:
 	exception_exit(prev_state);
 }
@@ -385,13 +384,13 @@ void sun4v_data_access_exception(struct pt_regs *regs, unsigned long addr, unsig
 	 */
 	switch (type) {
 	case HV_FAULT_TYPE_INV_ASI:
-		force_sig_fault(SIGILL, ILL_ILLADR, (void __user *)addr, 0);
+		force_sig_fault(SIGILL, ILL_ILLADR, (void __user *)addr);
 		break;
 	case HV_FAULT_TYPE_MCD_DIS:
-		force_sig_fault(SIGSEGV, SEGV_ACCADI, (void __user *)addr, 0);
+		force_sig_fault(SIGSEGV, SEGV_ACCADI, (void __user *)addr);
 		break;
 	default:
-		force_sig_fault(SIGSEGV, SEGV_MAPERR, (void __user *)addr, 0);
+		force_sig_fault(SIGSEGV, SEGV_MAPERR, (void __user *)addr);
 		break;
 	}
 }
@@ -568,7 +567,7 @@ static void spitfire_ue_log(unsigned long afsr, unsigned long afar, unsigned lon
 		regs->tpc &= 0xffffffff;
 		regs->tnpc &= 0xffffffff;
 	}
-	force_sig_fault(SIGBUS, BUS_OBJERR, (void *)0, 0);
+	force_sig_fault(SIGBUS, BUS_OBJERR, (void *)0);
 }
 
 void spitfire_access_error(struct pt_regs *regs, unsigned long status_encoded, unsigned long afar)
@@ -2069,8 +2068,7 @@ void do_mcd_err(struct pt_regs *regs, struct sun4v_error_entry ent)
 	/* Send SIGSEGV to the userspace process with the right signal
 	 * code
 	 */
-	force_sig_fault(SIGSEGV, SEGV_ADIDERR, (void __user *)ent.err_raddr,
-			0);
+	force_sig_fault(SIGSEGV, SEGV_ADIDERR, (void __user *)ent.err_raddr);
 }
 
 /* We run with %pil set to PIL_NORMAL_MAX and PSTATE_IE enabled in %pstate.
@@ -2184,7 +2182,7 @@ bool sun4v_nonresum_error_user_handled(struct pt_regs *regs,
 	}
 	if (attrs & SUN4V_ERR_ATTRS_PIO) {
 		force_sig_fault(SIGBUS, BUS_ADRERR,
-				(void __user *)sun4v_get_vaddr(regs), 0);
+				(void __user *)sun4v_get_vaddr(regs));
 		return true;
 	}
 
@@ -2340,8 +2338,7 @@ static void do_fpe_common(struct pt_regs *regs)
 			else if (fsr & 0x01)
 				code = FPE_FLTRES;
 		}
-		force_sig_fault(SIGFPE, code,
-				(void __user *)regs->tpc, 0);
+		force_sig_fault(SIGFPE, code, (void __user *)regs->tpc);
 	}
 }
 
@@ -2395,8 +2392,7 @@ void do_tof(struct pt_regs *regs)
 		regs->tpc &= 0xffffffff;
 		regs->tnpc &= 0xffffffff;
 	}
-	force_sig_fault(SIGEMT, EMT_TAGOVF,
-			(void __user *)regs->tpc, 0);
+	force_sig_fault(SIGEMT, EMT_TAGOVF, (void __user *)regs->tpc);
 out:
 	exception_exit(prev_state);
 }
@@ -2415,8 +2411,7 @@ void do_div0(struct pt_regs *regs)
 		regs->tpc &= 0xffffffff;
 		regs->tnpc &= 0xffffffff;
 	}
-	force_sig_fault(SIGFPE, FPE_INTDIV,
-			(void __user *)regs->tpc, 0);
+	force_sig_fault(SIGFPE, FPE_INTDIV, (void __user *)regs->tpc);
 out:
 	exception_exit(prev_state);
 }
@@ -2612,7 +2607,7 @@ void do_illegal_instruction(struct pt_regs *regs)
 			}
 		}
 	}
-	force_sig_fault(SIGILL, ILL_ILLOPC, (void __user *)pc, 0);
+	force_sig_fault(SIGILL, ILL_ILLOPC, (void __user *)pc);
 out:
 	exception_exit(prev_state);
 }
@@ -2632,7 +2627,7 @@ void mem_address_unaligned(struct pt_regs *regs, unsigned long sfar, unsigned lo
 	if (is_no_fault_exception(regs))
 		return;
 
-	force_sig_fault(SIGBUS, BUS_ADRALN, (void __user *)sfar, 0);
+	force_sig_fault(SIGBUS, BUS_ADRALN, (void __user *)sfar);
 out:
 	exception_exit(prev_state);
 }
@@ -2650,7 +2645,7 @@ void sun4v_do_mna(struct pt_regs *regs, unsigned long addr, unsigned long type_c
 	if (is_no_fault_exception(regs))
 		return;
 
-	force_sig_fault(SIGBUS, BUS_ADRALN, (void __user *) addr, 0);
+	force_sig_fault(SIGBUS, BUS_ADRALN, (void __user *) addr);
 }
 
 /* sun4v_mem_corrupt_detect_precise() - Handle precise exception on an ADI
@@ -2697,7 +2692,7 @@ void sun4v_mem_corrupt_detect_precise(struct pt_regs *regs, unsigned long addr,
 		regs->tpc &= 0xffffffff;
 		regs->tnpc &= 0xffffffff;
 	}
-	force_sig_fault(SIGSEGV, SEGV_ADIPERR, (void __user *)addr, 0);
+	force_sig_fault(SIGSEGV, SEGV_ADIPERR, (void __user *)addr);
 }
 
 void do_privop(struct pt_regs *regs)
@@ -2712,8 +2707,7 @@ void do_privop(struct pt_regs *regs)
 		regs->tpc &= 0xffffffff;
 		regs->tnpc &= 0xffffffff;
 	}
-	force_sig_fault(SIGILL, ILL_PRVOPC,
-			(void __user *)regs->tpc, 0);
+	force_sig_fault(SIGILL, ILL_PRVOPC, (void __user *)regs->tpc);
 out:
 	exception_exit(prev_state);
 }
diff --git a/arch/sparc/kernel/unaligned_32.c b/arch/sparc/kernel/unaligned_32.c
index ef5c5207c9ff..455f0258c745 100644
--- a/arch/sparc/kernel/unaligned_32.c
+++ b/arch/sparc/kernel/unaligned_32.c
@@ -278,5 +278,5 @@ asmlinkage void user_unaligned_trap(struct pt_regs *regs, unsigned int insn)
 {
 	send_sig_fault(SIGBUS, BUS_ADRALN,
 		       (void __user *)safe_compute_effective_address(regs, insn),
-		       0, current);
+		       current);
 }
diff --git a/arch/sparc/mm/fault_32.c b/arch/sparc/mm/fault_32.c
index de2031c2b2d7..fa858626b85b 100644
--- a/arch/sparc/mm/fault_32.c
+++ b/arch/sparc/mm/fault_32.c
@@ -83,7 +83,7 @@ static void __do_fault_siginfo(int code, int sig, struct pt_regs *regs,
 		show_signal_msg(regs, sig, code,
 				addr, current);
 
-	force_sig_fault(sig, code, (void __user *) addr, 0);
+	force_sig_fault(sig, code, (void __user *) addr);
 }
 
 static unsigned long compute_si_addr(struct pt_regs *regs, int text_fault)
diff --git a/arch/sparc/mm/fault_64.c b/arch/sparc/mm/fault_64.c
index 0a6bcc85fba7..9a9652a15fed 100644
--- a/arch/sparc/mm/fault_64.c
+++ b/arch/sparc/mm/fault_64.c
@@ -176,7 +176,7 @@ static void do_fault_siginfo(int code, int sig, struct pt_regs *regs,
 	if (unlikely(show_unhandled_signals))
 		show_signal_msg(regs, sig, code, addr, current);
 
-	force_sig_fault(sig, code, (void __user *) addr, 0);
+	force_sig_fault(sig, code, (void __user *) addr);
 }
 
 static unsigned int get_fault_insn(struct pt_regs *regs, unsigned int insn)
diff --git a/include/linux/sched/signal.h b/include/linux/sched/signal.h
index 3f6a0fcaa10c..7daa425f3055 100644
--- a/include/linux/sched/signal.h
+++ b/include/linux/sched/signal.h
@@ -298,11 +298,6 @@ static inline void kernel_signal_stop(void)
 
 	schedule();
 }
-#ifdef __ARCH_SI_TRAPNO
-# define ___ARCH_SI_TRAPNO(_a1) , _a1
-#else
-# define ___ARCH_SI_TRAPNO(_a1)
-#endif
 #ifdef __ia64__
 # define ___ARCH_SI_IA64(_a1, _a2, _a3) , _a1, _a2, _a3
 #else
@@ -310,14 +305,11 @@ static inline void kernel_signal_stop(void)
 #endif
 
 int force_sig_fault_to_task(int sig, int code, void __user *addr
-	___ARCH_SI_TRAPNO(int trapno)
 	___ARCH_SI_IA64(int imm, unsigned int flags, unsigned long isr)
 	, struct task_struct *t);
 int force_sig_fault(int sig, int code, void __user *addr
-	___ARCH_SI_TRAPNO(int trapno)
 	___ARCH_SI_IA64(int imm, unsigned int flags, unsigned long isr));
 int send_sig_fault(int sig, int code, void __user *addr
-	___ARCH_SI_TRAPNO(int trapno)
 	___ARCH_SI_IA64(int imm, unsigned int flags, unsigned long isr)
 	, struct task_struct *t);
 
@@ -327,6 +319,10 @@ int send_sig_mceerr(int code, void __user *, short, struct task_struct *);
 int force_sig_bnderr(void __user *addr, void __user *lower, void __user *upper);
 int force_sig_pkuerr(void __user *addr, u32 pkey);
 
+int force_sig_fault_trapno(int sig, int code, void __user *addr, int trapno);
+int send_sig_fault_trapno(int sig, int code, void __user *addr, int trapno,
+			  struct task_struct *task);
+
 int force_sig_ptrace_errno_trap(int errno, void __user *addr);
 
 extern int send_sig_info(int, struct kernel_siginfo *, struct task_struct *);
diff --git a/kernel/signal.c b/kernel/signal.c
index 3d3ba7949788..7eaa8d84db4c 100644
--- a/kernel/signal.c
+++ b/kernel/signal.c
@@ -1651,7 +1651,6 @@ void force_sigsegv(int sig)
 }
 
 int force_sig_fault_to_task(int sig, int code, void __user *addr
-	___ARCH_SI_TRAPNO(int trapno)
 	___ARCH_SI_IA64(int imm, unsigned int flags, unsigned long isr)
 	, struct task_struct *t)
 {
@@ -1662,9 +1661,6 @@ int force_sig_fault_to_task(int sig, int code, void __user *addr
 	info.si_errno = 0;
 	info.si_code  = code;
 	info.si_addr  = addr;
-#ifdef __ARCH_SI_TRAPNO
-	info.si_trapno = trapno;
-#endif
 #ifdef __ia64__
 	info.si_imm = imm;
 	info.si_flags = flags;
@@ -1674,16 +1670,13 @@ int force_sig_fault_to_task(int sig, int code, void __user *addr
 }
 
 int force_sig_fault(int sig, int code, void __user *addr
-	___ARCH_SI_TRAPNO(int trapno)
 	___ARCH_SI_IA64(int imm, unsigned int flags, unsigned long isr))
 {
 	return force_sig_fault_to_task(sig, code, addr
-				       ___ARCH_SI_TRAPNO(trapno)
 				       ___ARCH_SI_IA64(imm, flags, isr), current);
 }
 
 int send_sig_fault(int sig, int code, void __user *addr
-	___ARCH_SI_TRAPNO(int trapno)
 	___ARCH_SI_IA64(int imm, unsigned int flags, unsigned long isr)
 	, struct task_struct *t)
 {
@@ -1694,9 +1687,6 @@ int send_sig_fault(int sig, int code, void __user *addr
 	info.si_errno = 0;
 	info.si_code  = code;
 	info.si_addr  = addr;
-#ifdef __ARCH_SI_TRAPNO
-	info.si_trapno = trapno;
-#endif
 #ifdef __ia64__
 	info.si_imm = imm;
 	info.si_flags = flags;
@@ -1763,6 +1753,37 @@ int force_sig_pkuerr(void __user *addr, u32 pkey)
 }
 #endif
 
+#if IS_ENABLED(CONFIG_SPARC)
+int force_sig_fault_trapno(int sig, int code, void __user *addr, int trapno)
+{
+	struct kernel_siginfo info;
+
+	clear_siginfo(&info);
+	info.si_signo = sig;
+	info.si_errno = 0;
+	info.si_code  = code;
+	info.si_addr  = addr;
+	info.si_trapno = trapno;
+	return force_sig_info(&info);
+}
+#endif
+
+#if IS_ENABLED(CONFIG_ALPHA)
+int send_sig_fault_trapno(int sig, int code, void __user *addr, int trapno,
+			  struct task_struct *t)
+{
+	struct kernel_siginfo info;
+
+	clear_siginfo(&info);
+	info.si_signo = sig;
+	info.si_errno = 0;
+	info.si_code  = code;
+	info.si_addr  = addr;
+	info.si_trapno = trapno;
+	return send_sig_info(info.si_signo, &info, t);
+}
+#endif
+
 /* For the crazy architectures that include trap information in
  * the errno field, instead of an actual errno value.
  */
-- 
2.30.1

[PATCH 07/12] signal: Remove __ARCH_SI_TRAPNO

[Eric W. Beiderman]

From: "Eric W. Biederman" <ebiederm@xmission.com>

Now that this define is no longer used remove it from the kernel.

v1: https://lkml.kernel.org/r/m18s4zs7nu.fsf_-_@fess.ebiederm.org
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
---
 arch/alpha/include/uapi/asm/siginfo.h | 2 --
 arch/mips/include/uapi/asm/siginfo.h  | 2 --
 arch/sparc/include/uapi/asm/siginfo.h | 3 ---
 3 files changed, 7 deletions(-)

diff --git a/arch/alpha/include/uapi/asm/siginfo.h b/arch/alpha/include/uapi/asm/siginfo.h
index 6e1a2af2f962..e08eae88182b 100644
--- a/arch/alpha/include/uapi/asm/siginfo.h
+++ b/arch/alpha/include/uapi/asm/siginfo.h
@@ -2,8 +2,6 @@
 #ifndef _ALPHA_SIGINFO_H
 #define _ALPHA_SIGINFO_H
 
-#define __ARCH_SI_TRAPNO
-
 #include <asm-generic/siginfo.h>
 
 #endif
diff --git a/arch/mips/include/uapi/asm/siginfo.h b/arch/mips/include/uapi/asm/siginfo.h
index c34c7eef0a1c..8cb8bd061a68 100644
--- a/arch/mips/include/uapi/asm/siginfo.h
+++ b/arch/mips/include/uapi/asm/siginfo.h
@@ -10,9 +10,7 @@
 #ifndef _UAPI_ASM_SIGINFO_H
 #define _UAPI_ASM_SIGINFO_H
 
-
 #define __ARCH_SIGEV_PREAMBLE_SIZE (sizeof(long) + 2*sizeof(int))
-#undef __ARCH_SI_TRAPNO /* exception code needs to fill this ...  */
 
 #define __ARCH_HAS_SWAPPED_SIGINFO
 
diff --git a/arch/sparc/include/uapi/asm/siginfo.h b/arch/sparc/include/uapi/asm/siginfo.h
index 68bdde4c2a2e..0e7c27522aed 100644
--- a/arch/sparc/include/uapi/asm/siginfo.h
+++ b/arch/sparc/include/uapi/asm/siginfo.h
@@ -8,9 +8,6 @@
 
 #endif /* defined(__sparc__) && defined(__arch64__) */
 
-
-#define __ARCH_SI_TRAPNO
-
 #include <asm-generic/siginfo.h>
 
 
-- 
2.30.1

[PATCH 08/12] signal: Rename SIL_PERF_EVENT SIL_FAULT_PERF_EVENT for consistency

[Eric W. Beiderman]

From: "Eric W. Biederman" <ebiederm@xmission.com>

It helps to know which part of the siginfo structure the siginfo_layout
value is talking about.

v1: https://lkml.kernel.org/r/m18s4zs7nu.fsf_-_@fess.ebiederm.org
Acked-by: Marco Elver <elver@google.com>
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
---
 fs/signalfd.c          |  2 +-
 include/linux/signal.h |  2 +-
 kernel/signal.c        | 10 +++++-----
 3 files changed, 7 insertions(+), 7 deletions(-)

diff --git a/fs/signalfd.c b/fs/signalfd.c
index e87e59581653..83130244f653 100644
--- a/fs/signalfd.c
+++ b/fs/signalfd.c
@@ -132,7 +132,7 @@ static int signalfd_copyinfo(struct signalfd_siginfo __user *uinfo,
 		new.ssi_addr = (long) kinfo->si_addr;
 		new.ssi_addr_lsb = (short) kinfo->si_addr_lsb;
 		break;
-	case SIL_PERF_EVENT:
+	case SIL_FAULT_PERF_EVENT:
 		new.ssi_addr = (long) kinfo->si_addr;
 		new.ssi_perf = kinfo->si_perf;
 		break;
diff --git a/include/linux/signal.h b/include/linux/signal.h
index 5160fd45e5ca..ed896d790e46 100644
--- a/include/linux/signal.h
+++ b/include/linux/signal.h
@@ -44,7 +44,7 @@ enum siginfo_layout {
 	SIL_FAULT_MCEERR,
 	SIL_FAULT_BNDERR,
 	SIL_FAULT_PKUERR,
-	SIL_PERF_EVENT,
+	SIL_FAULT_PERF_EVENT,
 	SIL_CHLD,
 	SIL_RT,
 	SIL_SYS,
diff --git a/kernel/signal.c b/kernel/signal.c
index 7eaa8d84db4c..697c5fe58db8 100644
--- a/kernel/signal.c
+++ b/kernel/signal.c
@@ -1198,7 +1198,7 @@ static inline bool has_si_pid_and_uid(struct kernel_siginfo *info)
 	case SIL_FAULT_MCEERR:
 	case SIL_FAULT_BNDERR:
 	case SIL_FAULT_PKUERR:
-	case SIL_PERF_EVENT:
+	case SIL_FAULT_PERF_EVENT:
 	case SIL_SYS:
 		ret = false;
 		break;
@@ -2553,7 +2553,7 @@ static void hide_si_addr_tag_bits(struct ksignal *ksig)
 	case SIL_FAULT_MCEERR:
 	case SIL_FAULT_BNDERR:
 	case SIL_FAULT_PKUERR:
-	case SIL_PERF_EVENT:
+	case SIL_FAULT_PERF_EVENT:
 		ksig->info.si_addr = arch_untagged_si_addr(
 			ksig->info.si_addr, ksig->sig, ksig->info.si_code);
 		break;
@@ -3243,7 +3243,7 @@ enum siginfo_layout siginfo_layout(unsigned sig, int si_code)
 				layout = SIL_FAULT_PKUERR;
 #endif
 			else if ((sig == SIGTRAP) && (si_code == TRAP_PERF))
-				layout = SIL_PERF_EVENT;
+				layout = SIL_FAULT_PERF_EVENT;
 		}
 		else if (si_code <= NSIGPOLL)
 			layout = SIL_POLL;
@@ -3365,7 +3365,7 @@ void copy_siginfo_to_external32(struct compat_siginfo *to,
 		to->si_addr = ptr_to_compat(from->si_addr);
 		to->si_pkey = from->si_pkey;
 		break;
-	case SIL_PERF_EVENT:
+	case SIL_FAULT_PERF_EVENT:
 		to->si_addr = ptr_to_compat(from->si_addr);
 		to->si_perf = from->si_perf;
 		break;
@@ -3441,7 +3441,7 @@ static int post_copy_siginfo_from_user32(kernel_siginfo_t *to,
 		to->si_addr = compat_ptr(from->si_addr);
 		to->si_pkey = from->si_pkey;
 		break;
-	case SIL_PERF_EVENT:
+	case SIL_FAULT_PERF_EVENT:
 		to->si_addr = compat_ptr(from->si_addr);
 		to->si_perf = from->si_perf;
 		break;
-- 
2.30.1

[PATCH 09/12] signal: Factor force_sig_perf out of perf_sigtrap

[Eric W. Beiderman]

From: "Eric W. Biederman" <ebiederm@xmission.com>

Separate generating the signal from deciding it needs to be sent.

v1: https://lkml.kernel.org/r/m17dkjqqxz.fsf_-_@fess.ebiederm.org
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
---
 include/linux/sched/signal.h |  1 +
 kernel/events/core.c         | 11 ++---------
 kernel/signal.c              | 13 +++++++++++++
 3 files changed, 16 insertions(+), 9 deletions(-)

diff --git a/include/linux/sched/signal.h b/include/linux/sched/signal.h
index 7daa425f3055..1e2f61a1a512 100644
--- a/include/linux/sched/signal.h
+++ b/include/linux/sched/signal.h
@@ -318,6 +318,7 @@ int send_sig_mceerr(int code, void __user *, short, struct task_struct *);
 
 int force_sig_bnderr(void __user *addr, void __user *lower, void __user *upper);
 int force_sig_pkuerr(void __user *addr, u32 pkey);
+int force_sig_perf(void __user *addr, u32 type, u64 sig_data);
 
 int force_sig_fault_trapno(int sig, int code, void __user *addr, int trapno);
 int send_sig_fault_trapno(int sig, int code, void __user *addr, int trapno,
diff --git a/kernel/events/core.c b/kernel/events/core.c
index 928b166d888e..48ea8863183b 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -6394,8 +6394,6 @@ void perf_event_wakeup(struct perf_event *event)
 
 static void perf_sigtrap(struct perf_event *event)
 {
-	struct kernel_siginfo info;
-
 	/*
 	 * We'd expect this to only occur if the irq_work is delayed and either
 	 * ctx->task or current has changed in the meantime. This can be the
@@ -6410,13 +6408,8 @@ static void perf_sigtrap(struct perf_event *event)
 	if (current->flags & PF_EXITING)
 		return;
 
-	clear_siginfo(&info);
-	info.si_signo = SIGTRAP;
-	info.si_code = TRAP_PERF;
-	info.si_errno = event->attr.type;
-	info.si_perf = event->attr.sig_data;
-	info.si_addr = (void __user *)event->pending_addr;
-	force_sig_info(&info);
+	force_sig_perf((void __user *)event->pending_addr,
+		       event->attr.type, event->attr.sig_data);
 }
 
 static void perf_pending_event_disable(struct perf_event *event)
diff --git a/kernel/signal.c b/kernel/signal.c
index 697c5fe58db8..49560ceac048 100644
--- a/kernel/signal.c
+++ b/kernel/signal.c
@@ -1753,6 +1753,19 @@ int force_sig_pkuerr(void __user *addr, u32 pkey)
 }
 #endif
 
+int force_sig_perf(void __user *addr, u32 type, u64 sig_data)
+{
+	struct kernel_siginfo info;
+
+	clear_siginfo(&info);
+	info.si_signo = SIGTRAP;
+	info.si_errno = type;
+	info.si_code  = TRAP_PERF;
+	info.si_addr  = addr;
+	info.si_perf  = sig_data;
+	return force_sig_info(&info);
+}
+
 #if IS_ENABLED(CONFIG_SPARC)
 int force_sig_fault_trapno(int sig, int code, void __user *addr, int trapno)
 {
-- 
2.30.1

[PATCH 10/12] signal: Redefine signinfo so 64bit fields are possible

[Eric W. Beiderman]

From: "Eric W. Biederman" <ebiederm@xmission.com>

The si_perf code really wants to add a u64 field.  This change enables
that by reorganizing the definition of siginfo_t, so that a 64bit
field can be added without increasing the alignment of other fields.

Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
---
 arch/x86/kernel/signal_compat.c    |  9 +++----
 include/linux/compat.h             | 28 +++++++++++++-------
 include/uapi/asm-generic/siginfo.h | 42 ++++++++++++++++++++----------
 3 files changed, 49 insertions(+), 30 deletions(-)

diff --git a/arch/x86/kernel/signal_compat.c b/arch/x86/kernel/signal_compat.c
index a9fcabd8a5e5..a5cd01c52dfb 100644
--- a/arch/x86/kernel/signal_compat.c
+++ b/arch/x86/kernel/signal_compat.c
@@ -17,8 +17,6 @@
  */
 static inline void signal_compat_build_tests(void)
 {
-	int _sifields_offset = offsetof(compat_siginfo_t, _sifields);
-
 	/*
 	 * If adding a new si_code, there is probably new data in
 	 * the siginfo.  Make sure folks bumping the si_code
@@ -40,8 +38,7 @@ static inline void signal_compat_build_tests(void)
 	 * in the ABI, of course.  Make sure none of them ever
 	 * move and are always at the beginning:
 	 */
-	BUILD_BUG_ON(offsetof(compat_siginfo_t, _sifields) != 3 * sizeof(int));
-#define CHECK_CSI_OFFSET(name)	  BUILD_BUG_ON(_sifields_offset != offsetof(compat_siginfo_t, _sifields.name))
+#define CHECK_CSI_OFFSET(name)	  BUILD_BUG_ON(0 != offsetof(compat_siginfo_t, _sifields.name))
 
 	BUILD_BUG_ON(offsetof(siginfo_t, si_signo) != 0);
 	BUILD_BUG_ON(offsetof(siginfo_t, si_errno) != 4);
@@ -63,8 +60,8 @@ static inline void signal_compat_build_tests(void)
 	 * structure stays within the padding size (checked
 	 * above).
 	 */
-#define CHECK_CSI_SIZE(name, size) BUILD_BUG_ON(size != sizeof(((compat_siginfo_t *)0)->_sifields.name))
-#define CHECK_SI_SIZE(name, size) BUILD_BUG_ON(size != sizeof(((siginfo_t *)0)->_sifields.name))
+#define CHECK_CSI_SIZE(name, size) BUILD_BUG_ON(((3*sizeof(int))+(size)) != sizeof(((compat_siginfo_t *)0)->_sifields.name))
+#define CHECK_SI_SIZE(name, size) BUILD_BUG_ON(((4*sizeof(int))+(size)) != sizeof(((siginfo_t *)0)->_sifields.name))
 
 	CHECK_CSI_OFFSET(_kill);
 	CHECK_CSI_SIZE  (_kill, 2*sizeof(int));
diff --git a/include/linux/compat.h b/include/linux/compat.h
index 6af7bef15e94..d81493248bf3 100644
--- a/include/linux/compat.h
+++ b/include/linux/compat.h
@@ -158,27 +158,28 @@ typedef union compat_sigval {
 	compat_uptr_t	sival_ptr;
 } compat_sigval_t;
 
-typedef struct compat_siginfo {
-	int si_signo;
-#ifndef __ARCH_HAS_SWAPPED_SIGINFO
-	int si_errno;
-	int si_code;
-#else
-	int si_code;
-	int si_errno;
-#endif
+#define __COMPAT_SIGINFO_COMMON	\
+	___SIGINFO_COMMON;	\
+	int	_common_pad[__alignof__(compat_uptr_t) != __alignof__(int)]
 
+typedef struct compat_siginfo {
+	union {
+		struct {
+			__COMPAT_SIGINFO_COMMON;
+		};
 	union {
-		int _pad[128/sizeof(int) - 3];
+		int _pad[128/sizeof(int)];
 
 		/* kill() */
 		struct {
+			__COMPAT_SIGINFO_COMMON;
 			compat_pid_t _pid;	/* sender's pid */
 			__compat_uid32_t _uid;	/* sender's uid */
 		} _kill;
 
 		/* POSIX.1b timers */
 		struct {
+			__COMPAT_SIGINFO_COMMON;
 			compat_timer_t _tid;	/* timer id */
 			int _overrun;		/* overrun count */
 			compat_sigval_t _sigval;	/* same as below */
@@ -186,6 +187,7 @@ typedef struct compat_siginfo {
 
 		/* POSIX.1b signals */
 		struct {
+			__COMPAT_SIGINFO_COMMON;
 			compat_pid_t _pid;	/* sender's pid */
 			__compat_uid32_t _uid;	/* sender's uid */
 			compat_sigval_t _sigval;
@@ -193,6 +195,7 @@ typedef struct compat_siginfo {
 
 		/* SIGCHLD */
 		struct {
+			__COMPAT_SIGINFO_COMMON;
 			compat_pid_t _pid;	/* which child */
 			__compat_uid32_t _uid;	/* sender's uid */
 			int _status;		/* exit code */
@@ -203,6 +206,7 @@ typedef struct compat_siginfo {
 #ifdef CONFIG_X86_X32_ABI
 		/* SIGCHLD (x32 version) */
 		struct {
+			__COMPAT_SIGINFO_COMMON;
 			compat_pid_t _pid;	/* which child */
 			__compat_uid32_t _uid;	/* sender's uid */
 			int _status;		/* exit code */
@@ -213,6 +217,7 @@ typedef struct compat_siginfo {
 
 		/* SIGILL, SIGFPE, SIGSEGV, SIGBUS, SIGTRAP, SIGEMT */
 		struct {
+			__COMPAT_SIGINFO_COMMON;
 			compat_uptr_t _addr;	/* faulting insn/memory ref. */
 #define __COMPAT_ADDR_BND_PKEY_PAD  (__alignof__(compat_uptr_t) < sizeof(short) ? \
 				     sizeof(short) : __alignof__(compat_uptr_t))
@@ -242,16 +247,19 @@ typedef struct compat_siginfo {
 
 		/* SIGPOLL */
 		struct {
+			__COMPAT_SIGINFO_COMMON;
 			compat_long_t _band;	/* POLL_IN, POLL_OUT, POLL_MSG */
 			int _fd;
 		} _sigpoll;
 
 		struct {
+			__COMPAT_SIGINFO_COMMON;
 			compat_uptr_t _call_addr; /* calling user insn */
 			int _syscall;	/* triggering system call number */
 			unsigned int _arch;	/* AUDIT_ARCH_* of syscall */
 		} _sigsys;
 	} _sifields;
+	};
 } compat_siginfo_t;
 
 struct compat_rlimit {
diff --git a/include/uapi/asm-generic/siginfo.h b/include/uapi/asm-generic/siginfo.h
index e663bf117b46..1fcede623a73 100644
--- a/include/uapi/asm-generic/siginfo.h
+++ b/include/uapi/asm-generic/siginfo.h
@@ -29,15 +29,33 @@ typedef union sigval {
 #define __ARCH_SI_ATTRIBUTES
 #endif
 
+#ifndef __ARCH_HAS_SWAPPED_SIGINFO
+#define ___SIGINFO_COMMON	\
+	int	si_signo;	\
+	int	si_errno;	\
+	int	si_code
+#else
+#define ___SIGINFO_COMMON	\
+	int	si_signo;	\
+	int	si_code;	\
+	int	si_errno
+#endif /* __ARCH_HAS_SWAPPED_SIGINFO */
+
+#define __SIGINFO_COMMON	\
+	___SIGINFO_COMMON;	\
+	int	_common_pad[__alignof__(void *) != __alignof(int)]
+
 union __sifields {
 	/* kill() */
 	struct {
+		__SIGINFO_COMMON;
 		__kernel_pid_t _pid;	/* sender's pid */
 		__kernel_uid32_t _uid;	/* sender's uid */
 	} _kill;
 
 	/* POSIX.1b timers */
 	struct {
+		__SIGINFO_COMMON;
 		__kernel_timer_t _tid;	/* timer id */
 		int _overrun;		/* overrun count */
 		sigval_t _sigval;	/* same as below */
@@ -46,6 +64,7 @@ union __sifields {
 
 	/* POSIX.1b signals */
 	struct {
+		__SIGINFO_COMMON;
 		__kernel_pid_t _pid;	/* sender's pid */
 		__kernel_uid32_t _uid;	/* sender's uid */
 		sigval_t _sigval;
@@ -53,6 +72,7 @@ union __sifields {
 
 	/* SIGCHLD */
 	struct {
+		__SIGINFO_COMMON;
 		__kernel_pid_t _pid;	/* which child */
 		__kernel_uid32_t _uid;	/* sender's uid */
 		int _status;		/* exit code */
@@ -62,6 +82,7 @@ union __sifields {
 
 	/* SIGILL, SIGFPE, SIGSEGV, SIGBUS, SIGTRAP, SIGEMT */
 	struct {
+		__SIGINFO_COMMON;
 		void __user *_addr; /* faulting insn/memory ref. */
 #ifdef __ia64__
 		int _imm;		/* immediate value for "break" */
@@ -97,35 +118,28 @@ union __sifields {
 
 	/* SIGPOLL */
 	struct {
+		__SIGINFO_COMMON;
 		__ARCH_SI_BAND_T _band;	/* POLL_IN, POLL_OUT, POLL_MSG */
 		int _fd;
 	} _sigpoll;
 
 	/* SIGSYS */
 	struct {
+		__SIGINFO_COMMON;
 		void __user *_call_addr; /* calling user insn */
 		int _syscall;	/* triggering system call number */
 		unsigned int _arch;	/* AUDIT_ARCH_* of syscall */
 	} _sigsys;
 };
 
-#ifndef __ARCH_HAS_SWAPPED_SIGINFO
-#define __SIGINFO 			\
-struct {				\
-	int si_signo;			\
-	int si_errno;			\
-	int si_code;			\
-	union __sifields _sifields;	\
-}
-#else
+
 #define __SIGINFO 			\
-struct {				\
-	int si_signo;			\
-	int si_code;			\
-	int si_errno;			\
+union {					\
+	struct {			\
+		__SIGINFO_COMMON;	\
+	};				\
 	union __sifields _sifields;	\
 }
-#endif /* __ARCH_HAS_SWAPPED_SIGINFO */
 
 typedef struct siginfo {
 	union {
-- 
2.30.1

Re: [PATCH 10/12] signal: Redefine signinfo so 64bit fields are possible

[Eric W. Biederman]

"Eric W. Beiderman" <ebiederm@xmission.com> writes:

> From: "Eric W. Biederman" <ebiederm@xmission.com>
>
> The si_perf code really wants to add a u64 field.  This change enables
> that by reorganizing the definition of siginfo_t, so that a 64bit
> field can be added without increasing the alignment of other fields.

I decided to include this change because it is not that complicated,
and it allows si_perf_data to have the definition that was originally
desired.

If this looks difficult to make in the userspace definitions,
or is otherwise a problem I don't mind dropping this change.  I just
figured since it was not too difficult and we are changing things
anyway I should try for everything.

Eric


> Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
> ---
>  arch/x86/kernel/signal_compat.c    |  9 +++----
>  include/linux/compat.h             | 28 +++++++++++++-------
>  include/uapi/asm-generic/siginfo.h | 42 ++++++++++++++++++++----------
>  3 files changed, 49 insertions(+), 30 deletions(-)
>
> diff --git a/arch/x86/kernel/signal_compat.c b/arch/x86/kernel/signal_compat.c
> index a9fcabd8a5e5..a5cd01c52dfb 100644
> --- a/arch/x86/kernel/signal_compat.c
> +++ b/arch/x86/kernel/signal_compat.c
> @@ -17,8 +17,6 @@
>   */
>  static inline void signal_compat_build_tests(void)
>  {
> -	int _sifields_offset = offsetof(compat_siginfo_t, _sifields);
> -
>  	/*
>  	 * If adding a new si_code, there is probably new data in
>  	 * the siginfo.  Make sure folks bumping the si_code
> @@ -40,8 +38,7 @@ static inline void signal_compat_build_tests(void)
>  	 * in the ABI, of course.  Make sure none of them ever
>  	 * move and are always at the beginning:
>  	 */
> -	BUILD_BUG_ON(offsetof(compat_siginfo_t, _sifields) != 3 * sizeof(int));
> -#define CHECK_CSI_OFFSET(name)	  BUILD_BUG_ON(_sifields_offset != offsetof(compat_siginfo_t, _sifields.name))
> +#define CHECK_CSI_OFFSET(name)	  BUILD_BUG_ON(0 != offsetof(compat_siginfo_t, _sifields.name))
>  
>  	BUILD_BUG_ON(offsetof(siginfo_t, si_signo) != 0);
>  	BUILD_BUG_ON(offsetof(siginfo_t, si_errno) != 4);
> @@ -63,8 +60,8 @@ static inline void signal_compat_build_tests(void)
>  	 * structure stays within the padding size (checked
>  	 * above).
>  	 */
> -#define CHECK_CSI_SIZE(name, size) BUILD_BUG_ON(size != sizeof(((compat_siginfo_t *)0)->_sifields.name))
> -#define CHECK_SI_SIZE(name, size) BUILD_BUG_ON(size != sizeof(((siginfo_t *)0)->_sifields.name))
> +#define CHECK_CSI_SIZE(name, size) BUILD_BUG_ON(((3*sizeof(int))+(size)) != sizeof(((compat_siginfo_t *)0)->_sifields.name))
> +#define CHECK_SI_SIZE(name, size) BUILD_BUG_ON(((4*sizeof(int))+(size)) != sizeof(((siginfo_t *)0)->_sifields.name))
>  
>  	CHECK_CSI_OFFSET(_kill);
>  	CHECK_CSI_SIZE  (_kill, 2*sizeof(int));
> diff --git a/include/linux/compat.h b/include/linux/compat.h
> index 6af7bef15e94..d81493248bf3 100644
> --- a/include/linux/compat.h
> +++ b/include/linux/compat.h
> @@ -158,27 +158,28 @@ typedef union compat_sigval {
>  	compat_uptr_t	sival_ptr;
>  } compat_sigval_t;
>  
> -typedef struct compat_siginfo {
> -	int si_signo;
> -#ifndef __ARCH_HAS_SWAPPED_SIGINFO
> -	int si_errno;
> -	int si_code;
> -#else
> -	int si_code;
> -	int si_errno;
> -#endif
> +#define __COMPAT_SIGINFO_COMMON	\
> +	___SIGINFO_COMMON;	\
> +	int	_common_pad[__alignof__(compat_uptr_t) != __alignof__(int)]
>  
> +typedef struct compat_siginfo {
> +	union {
> +		struct {
> +			__COMPAT_SIGINFO_COMMON;
> +		};
>  	union {
> -		int _pad[128/sizeof(int) - 3];
> +		int _pad[128/sizeof(int)];
>  
>  		/* kill() */
>  		struct {
> +			__COMPAT_SIGINFO_COMMON;
>  			compat_pid_t _pid;	/* sender's pid */
>  			__compat_uid32_t _uid;	/* sender's uid */
>  		} _kill;
>  
>  		/* POSIX.1b timers */
>  		struct {
> +			__COMPAT_SIGINFO_COMMON;
>  			compat_timer_t _tid;	/* timer id */
>  			int _overrun;		/* overrun count */
>  			compat_sigval_t _sigval;	/* same as below */
> @@ -186,6 +187,7 @@ typedef struct compat_siginfo {
>  
>  		/* POSIX.1b signals */
>  		struct {
> +			__COMPAT_SIGINFO_COMMON;
>  			compat_pid_t _pid;	/* sender's pid */
>  			__compat_uid32_t _uid;	/* sender's uid */
>  			compat_sigval_t _sigval;
> @@ -193,6 +195,7 @@ typedef struct compat_siginfo {
>  
>  		/* SIGCHLD */
>  		struct {
> +			__COMPAT_SIGINFO_COMMON;
>  			compat_pid_t _pid;	/* which child */
>  			__compat_uid32_t _uid;	/* sender's uid */
>  			int _status;		/* exit code */
> @@ -203,6 +206,7 @@ typedef struct compat_siginfo {
>  #ifdef CONFIG_X86_X32_ABI
>  		/* SIGCHLD (x32 version) */
>  		struct {
> +			__COMPAT_SIGINFO_COMMON;
>  			compat_pid_t _pid;	/* which child */
>  			__compat_uid32_t _uid;	/* sender's uid */
>  			int _status;		/* exit code */
> @@ -213,6 +217,7 @@ typedef struct compat_siginfo {
>  
>  		/* SIGILL, SIGFPE, SIGSEGV, SIGBUS, SIGTRAP, SIGEMT */
>  		struct {
> +			__COMPAT_SIGINFO_COMMON;
>  			compat_uptr_t _addr;	/* faulting insn/memory ref. */
>  #define __COMPAT_ADDR_BND_PKEY_PAD  (__alignof__(compat_uptr_t) < sizeof(short) ? \
>  				     sizeof(short) : __alignof__(compat_uptr_t))
> @@ -242,16 +247,19 @@ typedef struct compat_siginfo {
>  
>  		/* SIGPOLL */
>  		struct {
> +			__COMPAT_SIGINFO_COMMON;
>  			compat_long_t _band;	/* POLL_IN, POLL_OUT, POLL_MSG */
>  			int _fd;
>  		} _sigpoll;
>  
>  		struct {
> +			__COMPAT_SIGINFO_COMMON;
>  			compat_uptr_t _call_addr; /* calling user insn */
>  			int _syscall;	/* triggering system call number */
>  			unsigned int _arch;	/* AUDIT_ARCH_* of syscall */
>  		} _sigsys;
>  	} _sifields;
> +	};
>  } compat_siginfo_t;
>  
>  struct compat_rlimit {
> diff --git a/include/uapi/asm-generic/siginfo.h b/include/uapi/asm-generic/siginfo.h
> index e663bf117b46..1fcede623a73 100644
> --- a/include/uapi/asm-generic/siginfo.h
> +++ b/include/uapi/asm-generic/siginfo.h
> @@ -29,15 +29,33 @@ typedef union sigval {
>  #define __ARCH_SI_ATTRIBUTES
>  #endif
>  
> +#ifndef __ARCH_HAS_SWAPPED_SIGINFO
> +#define ___SIGINFO_COMMON	\
> +	int	si_signo;	\
> +	int	si_errno;	\
> +	int	si_code
> +#else
> +#define ___SIGINFO_COMMON	\
> +	int	si_signo;	\
> +	int	si_code;	\
> +	int	si_errno
> +#endif /* __ARCH_HAS_SWAPPED_SIGINFO */
> +
> +#define __SIGINFO_COMMON	\
> +	___SIGINFO_COMMON;	\
> +	int	_common_pad[__alignof__(void *) != __alignof(int)]
> +
>  union __sifields {
>  	/* kill() */
>  	struct {
> +		__SIGINFO_COMMON;
>  		__kernel_pid_t _pid;	/* sender's pid */
>  		__kernel_uid32_t _uid;	/* sender's uid */
>  	} _kill;
>  
>  	/* POSIX.1b timers */
>  	struct {
> +		__SIGINFO_COMMON;
>  		__kernel_timer_t _tid;	/* timer id */
>  		int _overrun;		/* overrun count */
>  		sigval_t _sigval;	/* same as below */
> @@ -46,6 +64,7 @@ union __sifields {
>  
>  	/* POSIX.1b signals */
>  	struct {
> +		__SIGINFO_COMMON;
>  		__kernel_pid_t _pid;	/* sender's pid */
>  		__kernel_uid32_t _uid;	/* sender's uid */
>  		sigval_t _sigval;
> @@ -53,6 +72,7 @@ union __sifields {
>  
>  	/* SIGCHLD */
>  	struct {
> +		__SIGINFO_COMMON;
>  		__kernel_pid_t _pid;	/* which child */
>  		__kernel_uid32_t _uid;	/* sender's uid */
>  		int _status;		/* exit code */
> @@ -62,6 +82,7 @@ union __sifields {
>  
>  	/* SIGILL, SIGFPE, SIGSEGV, SIGBUS, SIGTRAP, SIGEMT */
>  	struct {
> +		__SIGINFO_COMMON;
>  		void __user *_addr; /* faulting insn/memory ref. */
>  #ifdef __ia64__
>  		int _imm;		/* immediate value for "break" */
> @@ -97,35 +118,28 @@ union __sifields {
>  
>  	/* SIGPOLL */
>  	struct {
> +		__SIGINFO_COMMON;
>  		__ARCH_SI_BAND_T _band;	/* POLL_IN, POLL_OUT, POLL_MSG */
>  		int _fd;
>  	} _sigpoll;
>  
>  	/* SIGSYS */
>  	struct {
> +		__SIGINFO_COMMON;
>  		void __user *_call_addr; /* calling user insn */
>  		int _syscall;	/* triggering system call number */
>  		unsigned int _arch;	/* AUDIT_ARCH_* of syscall */
>  	} _sigsys;
>  };
>  
> -#ifndef __ARCH_HAS_SWAPPED_SIGINFO
> -#define __SIGINFO 			\
> -struct {				\
> -	int si_signo;			\
> -	int si_errno;			\
> -	int si_code;			\
> -	union __sifields _sifields;	\
> -}
> -#else
> +
>  #define __SIGINFO 			\
> -struct {				\
> -	int si_signo;			\
> -	int si_code;			\
> -	int si_errno;			\
> +union {					\
> +	struct {			\
> +		__SIGINFO_COMMON;	\
> +	};				\
>  	union __sifields _sifields;	\
>  }
> -#endif /* __ARCH_HAS_SWAPPED_SIGINFO */
>  
>  typedef struct siginfo {
>  	union {

Re: [PATCH 10/12] signal: Redefine signinfo so 64bit fields are possible

[Marco Elver]

On Mon, 3 May 2021 at 23:04, Eric W. Biederman <ebiederm@xmission.com> wrote:
> "Eric W. Beiderman" <ebiederm@xmission.com> writes:
> > From: "Eric W. Biederman" <ebiederm@xmission.com>
> >
> > The si_perf code really wants to add a u64 field.  This change enables
> > that by reorganizing the definition of siginfo_t, so that a 64bit
> > field can be added without increasing the alignment of other fields.

If you can, it'd be good to have an explanation for this, because it's
not at all obvious -- some future archeologist will wonder how we ever
came up with this definition of siginfo...

(I see the trick here is that before the union would have changed
alignment, introducing padding after the 3 ints -- but now because the
3 ints are inside the union the union's padding no longer adds padding
for these ints.  Perhaps you can explain it better than I can. Also
see below.)

> I decided to include this change because it is not that complicated,
> and it allows si_perf_data to have the definition that was originally
> desired.

Neat, and long-term I think this seems to be worth having. Sooner or
later something else might want __u64, too.

But right now, due to the slight increase in complexity, we need to
take extra care ensuring nothing broke -- at a high-level I see why
this seems to be safe.

> If this looks difficult to make in the userspace definitions,
> or is otherwise a problem I don't mind dropping this change.  I just
> figured since it was not too difficult and we are changing things
> anyway I should try for everything.

Languages that support inheritance might end up with the simpler
definition here (and depending on which fields they want to access,
they'd have to cast the base siginfo into the one they want). What
will become annoying is trying to describe siginfo_t.

I will run some tests in the morning.

Thanks,
-- Marco

[...]
> > diff --git a/include/uapi/asm-generic/siginfo.h b/include/uapi/asm-generic/siginfo.h
> > index e663bf117b46..1fcede623a73 100644
> > --- a/include/uapi/asm-generic/siginfo.h
> > +++ b/include/uapi/asm-generic/siginfo.h
> > @@ -29,15 +29,33 @@ typedef union sigval {
> >  #define __ARCH_SI_ATTRIBUTES
> >  #endif
> >
> > +#ifndef __ARCH_HAS_SWAPPED_SIGINFO
> > +#define ___SIGINFO_COMMON    \
> > +     int     si_signo;       \
> > +     int     si_errno;       \
> > +     int     si_code
> > +#else
> > +#define ___SIGINFO_COMMON    \
> > +     int     si_signo;       \
> > +     int     si_code;        \
> > +     int     si_errno
> > +#endif /* __ARCH_HAS_SWAPPED_SIGINFO */
> > +
> > +#define __SIGINFO_COMMON     \
> > +     ___SIGINFO_COMMON;      \
> > +     int     _common_pad[__alignof__(void *) != __alignof(int)]

Just to verify my understanding of _common_pad: this is again a legacy
problem, right? I.e. if siginfo was designed from the start like this,
we wouldn't need the _common_pad.


While this looks quite daunting, this is effectively turning siginfo
from a struct with a giant union, into lots of smaller structs, each
of which share a common header a'la inheritance -- until now the
distinction didn't matter, but it starts to matter as soon as
alignment of one child-struct would affect the offsets of another
child-struct (i.e. the old version). Right?

I was wondering if it would make things look cleaner if the above was
encapsulated in a struct, say __sicommon? Then the outermost union
would use 'struct __sicommon _sicommon' and we need #defines for
si_signo, si_code, and si_errno.

Or would it break alignment somewhere?

I leave it to your judgement -- just an idea.

> >  union __sifields {
> >       /* kill() */
> >       struct {
> > +             __SIGINFO_COMMON;
> >               __kernel_pid_t _pid;    /* sender's pid */
> >               __kernel_uid32_t _uid;  /* sender's uid */
> >       } _kill;
> >
> >       /* POSIX.1b timers */
> >       struct {
> > +             __SIGINFO_COMMON;
> >               __kernel_timer_t _tid;  /* timer id */
> >               int _overrun;           /* overrun count */
> >               sigval_t _sigval;       /* same as below */
> > @@ -46,6 +64,7 @@ union __sifields {
> >
> >       /* POSIX.1b signals */
> >       struct {
> > +             __SIGINFO_COMMON;
> >               __kernel_pid_t _pid;    /* sender's pid */
> >               __kernel_uid32_t _uid;  /* sender's uid */
> >               sigval_t _sigval;
> > @@ -53,6 +72,7 @@ union __sifields {
> >
> >       /* SIGCHLD */
> >       struct {
> > +             __SIGINFO_COMMON;
> >               __kernel_pid_t _pid;    /* which child */
> >               __kernel_uid32_t _uid;  /* sender's uid */
> >               int _status;            /* exit code */
> > @@ -62,6 +82,7 @@ union __sifields {
> >
> >       /* SIGILL, SIGFPE, SIGSEGV, SIGBUS, SIGTRAP, SIGEMT */
> >       struct {
> > +             __SIGINFO_COMMON;
> >               void __user *_addr; /* faulting insn/memory ref. */
> >  #ifdef __ia64__
> >               int _imm;               /* immediate value for "break" */
> > @@ -97,35 +118,28 @@ union __sifields {
> >
> >       /* SIGPOLL */
> >       struct {
> > +             __SIGINFO_COMMON;
> >               __ARCH_SI_BAND_T _band; /* POLL_IN, POLL_OUT, POLL_MSG */
> >               int _fd;
> >       } _sigpoll;
> >
> >       /* SIGSYS */
> >       struct {
> > +             __SIGINFO_COMMON;
> >               void __user *_call_addr; /* calling user insn */
> >               int _syscall;   /* triggering system call number */
> >               unsigned int _arch;     /* AUDIT_ARCH_* of syscall */
> >       } _sigsys;
> >  };
> >
> > -#ifndef __ARCH_HAS_SWAPPED_SIGINFO
> > -#define __SIGINFO                    \
> > -struct {                             \
> > -     int si_signo;                   \
> > -     int si_errno;                   \
> > -     int si_code;                    \
> > -     union __sifields _sifields;     \
> > -}
> > -#else
> > +
> >  #define __SIGINFO                    \
> > -struct {                             \
> > -     int si_signo;                   \
> > -     int si_code;                    \
> > -     int si_errno;                   \
> > +union {                                      \
> > +     struct {                        \
> > +             __SIGINFO_COMMON;       \
> > +     };                              \
> >       union __sifields _sifields;     \
> >  }
> > -#endif /* __ARCH_HAS_SWAPPED_SIGINFO */
> >
> >  typedef struct siginfo {
> >       union {

Re: [PATCH 10/12] signal: Redefine signinfo so 64bit fields are possible

[Eric W. Biederman]

Marco Elver <elver@google.com> writes:

> On Mon, 3 May 2021 at 23:04, Eric W. Biederman <ebiederm@xmission.com> wrote:
>> "Eric W. Beiderman" <ebiederm@xmission.com> writes:
>> > From: "Eric W. Biederman" <ebiederm@xmission.com>
>> >
>> > The si_perf code really wants to add a u64 field.  This change enables
>> > that by reorganizing the definition of siginfo_t, so that a 64bit
>> > field can be added without increasing the alignment of other fields.
>
> If you can, it'd be good to have an explanation for this, because it's
> not at all obvious -- some future archeologist will wonder how we ever
> came up with this definition of siginfo...
>
> (I see the trick here is that before the union would have changed
> alignment, introducing padding after the 3 ints -- but now because the
> 3 ints are inside the union the union's padding no longer adds padding
> for these ints.  Perhaps you can explain it better than I can. Also
> see below.)

Yes.  The big idea is adding a 64bit field into the second union
in the _sigfault case will increase the alignment of that second
union to 64bit.

In the 64bit case the alignment is already 64bit so it is not an
issue.

In the 32bit case there are 3 ints followed by a pointer.  When the
64bit member is added the alignment of _segfault becomes 64bit.  That
64bit alignment after 3 ints changes the location of the 32bit pointer.

By moving the 3 preceding ints into _segfault that does not happen.



There remains one very subtle issue that I think isn't a problem
but I would appreciate someone else double checking me.


The old definition of siginfo_t on 32bit almost certainly had 32bit
alignment.  With the addition of a 64bit member siginfo_t gains 64bit
alignment.  This difference only matters if the 64bit field is accessed.
Accessing a 64bit field with 32bit alignment will cause unaligned access
exceptions on some (most?) architectures.

For the 64bit field to be accessed the code needs to be recompiled with
the new headers.  Which implies that when everything is recompiled
siginfo_t will become 64bit aligned.


So the change should be safe unless someone is casting something with
32bit alignment into siginfo_t.


>
>> I decided to include this change because it is not that complicated,
>> and it allows si_perf_data to have the definition that was originally
>> desired.
>
> Neat, and long-term I think this seems to be worth having. Sooner or
> later something else might want __u64, too.
>
> But right now, due to the slight increase in complexity, we need to
> take extra care ensuring nothing broke -- at a high-level I see why
> this seems to be safe.

Absolutely.

>> If this looks difficult to make in the userspace definitions,
>> or is otherwise a problem I don't mind dropping this change.  I just
>> figured since it was not too difficult and we are changing things
>> anyway I should try for everything.
>
> Languages that support inheritance might end up with the simpler
> definition here (and depending on which fields they want to access,
> they'd have to cast the base siginfo into the one they want). What
> will become annoying is trying to describe siginfo_t.
>
> I will run some tests in the morning.
>
> Thanks,
> -- Marco
>
> [...]
>> > diff --git a/include/uapi/asm-generic/siginfo.h b/include/uapi/asm-generic/siginfo.h
>> > index e663bf117b46..1fcede623a73 100644
>> > --- a/include/uapi/asm-generic/siginfo.h
>> > +++ b/include/uapi/asm-generic/siginfo.h
>> > @@ -29,15 +29,33 @@ typedef union sigval {
>> >  #define __ARCH_SI_ATTRIBUTES
>> >  #endif
>> >
>> > +#ifndef __ARCH_HAS_SWAPPED_SIGINFO
>> > +#define ___SIGINFO_COMMON    \
>> > +     int     si_signo;       \
>> > +     int     si_errno;       \
>> > +     int     si_code
>> > +#else
>> > +#define ___SIGINFO_COMMON    \
>> > +     int     si_signo;       \
>> > +     int     si_code;        \
>> > +     int     si_errno
>> > +#endif /* __ARCH_HAS_SWAPPED_SIGINFO */
>> > +
>> > +#define __SIGINFO_COMMON     \
>> > +     ___SIGINFO_COMMON;      \
>> > +     int     _common_pad[__alignof__(void *) != __alignof(int)]
>
> Just to verify my understanding of _common_pad: this is again a legacy
> problem, right? I.e. if siginfo was designed from the start like this,
> we wouldn't need the _common_pad.

Correct.

If we are designing things carefully from the start the code could have
had a 64bit or a 128bit header that was common to all siginfo instances.
Then the trick of moving the header into each union member would not
have been necessary.

Unfortunately no one noticed until it was much too late to do anything
about it.

> While this looks quite daunting, this is effectively turning siginfo
> from a struct with a giant union, into lots of smaller structs, each
> of which share a common header a'la inheritance -- until now the
> distinction didn't matter, but it starts to matter as soon as
> alignment of one child-struct would affect the offsets of another
> child-struct (i.e. the old version). Right?

Correct.

> I was wondering if it would make things look cleaner if the above was
> encapsulated in a struct, say __sicommon? Then the outermost union
> would use 'struct __sicommon _sicommon' and we need #defines for
> si_signo, si_code, and si_errno.
>
> Or would it break alignment somewhere?
>
> I leave it to your judgement -- just an idea.

I tried it and kernel/signal.c would not compile because a few functions
have a parameter named si_code.  The kernel I could fix but there
is a chance some user space application has similar issues.

So to be safe si_signo, si_code, si_errno have to be available without
having a define.

Eric

Re: [PATCH 10/12] signal: Redefine signinfo so 64bit fields are possible

[Peter Collingbourne]

On Mon, May 3, 2021 at 8:42 PM Eric W. Biederman <ebiederm@xmission.com> wrote:
>
> Marco Elver <elver@google.com> writes:
>
> > On Mon, 3 May 2021 at 23:04, Eric W. Biederman <ebiederm@xmission.com> wrote:
> >> "Eric W. Beiderman" <ebiederm@xmission.com> writes:
> >> > From: "Eric W. Biederman" <ebiederm@xmission.com>
> >> >
> >> > The si_perf code really wants to add a u64 field.  This change enables
> >> > that by reorganizing the definition of siginfo_t, so that a 64bit
> >> > field can be added without increasing the alignment of other fields.
> >
> > If you can, it'd be good to have an explanation for this, because it's
> > not at all obvious -- some future archeologist will wonder how we ever
> > came up with this definition of siginfo...
> >
> > (I see the trick here is that before the union would have changed
> > alignment, introducing padding after the 3 ints -- but now because the
> > 3 ints are inside the union the union's padding no longer adds padding
> > for these ints.  Perhaps you can explain it better than I can. Also
> > see below.)
>
> Yes.  The big idea is adding a 64bit field into the second union
> in the _sigfault case will increase the alignment of that second
> union to 64bit.
>
> In the 64bit case the alignment is already 64bit so it is not an
> issue.
>
> In the 32bit case there are 3 ints followed by a pointer.  When the
> 64bit member is added the alignment of _segfault becomes 64bit.  That
> 64bit alignment after 3 ints changes the location of the 32bit pointer.
>
> By moving the 3 preceding ints into _segfault that does not happen.
>
>
>
> There remains one very subtle issue that I think isn't a problem
> but I would appreciate someone else double checking me.
>
>
> The old definition of siginfo_t on 32bit almost certainly had 32bit
> alignment.  With the addition of a 64bit member siginfo_t gains 64bit
> alignment.  This difference only matters if the 64bit field is accessed.
> Accessing a 64bit field with 32bit alignment will cause unaligned access
> exceptions on some (most?) architectures.
>
> For the 64bit field to be accessed the code needs to be recompiled with
> the new headers.  Which implies that when everything is recompiled
> siginfo_t will become 64bit aligned.
>
>
> So the change should be safe unless someone is casting something with
> 32bit alignment into siginfo_t.

How about if someone has a field of type siginfo_t as an element of a
struct? For example:

struct foo {
  int x;
  siginfo_t y;
};

With this change wouldn't the y field move from offset 4 to offset 8?

Peter

Re: [PATCH 10/12] signal: Redefine signinfo so 64bit fields are possible

[Marco Elver]

On Mon, May 03, 2021 at 09:03PM -0700, Peter Collingbourne wrote:
> On Mon, May 3, 2021 at 8:42 PM Eric W. Biederman <ebiederm@xmission.com> wrote:
> > Marco Elver <elver@google.com> writes:
> > > On Mon, 3 May 2021 at 23:04, Eric W. Biederman <ebiederm@xmission.com> wrote:
> > >> "Eric W. Beiderman" <ebiederm@xmission.com> writes:
> > >> > From: "Eric W. Biederman" <ebiederm@xmission.com>
> > >> >
> > >> > The si_perf code really wants to add a u64 field.  This change enables
> > >> > that by reorganizing the definition of siginfo_t, so that a 64bit
> > >> > field can be added without increasing the alignment of other fields.
> > >
> > > If you can, it'd be good to have an explanation for this, because it's
> > > not at all obvious -- some future archeologist will wonder how we ever
> > > came up with this definition of siginfo...
> > >
> > > (I see the trick here is that before the union would have changed
> > > alignment, introducing padding after the 3 ints -- but now because the
> > > 3 ints are inside the union the union's padding no longer adds padding
> > > for these ints.  Perhaps you can explain it better than I can. Also
> > > see below.)
> >
> > Yes.  The big idea is adding a 64bit field into the second union
> > in the _sigfault case will increase the alignment of that second
> > union to 64bit.
> >
> > In the 64bit case the alignment is already 64bit so it is not an
> > issue.
> >
> > In the 32bit case there are 3 ints followed by a pointer.  When the
> > 64bit member is added the alignment of _segfault becomes 64bit.  That
> > 64bit alignment after 3 ints changes the location of the 32bit pointer.
> >
> > By moving the 3 preceding ints into _segfault that does not happen.
> >
> >
> >
> > There remains one very subtle issue that I think isn't a problem
> > but I would appreciate someone else double checking me.
> >
> >
> > The old definition of siginfo_t on 32bit almost certainly had 32bit
> > alignment.  With the addition of a 64bit member siginfo_t gains 64bit
> > alignment.  This difference only matters if the 64bit field is accessed.
> > Accessing a 64bit field with 32bit alignment will cause unaligned access
> > exceptions on some (most?) architectures.
> >
> > For the 64bit field to be accessed the code needs to be recompiled with
> > the new headers.  Which implies that when everything is recompiled
> > siginfo_t will become 64bit aligned.
> >
> >
> > So the change should be safe unless someone is casting something with
> > 32bit alignment into siginfo_t.
> 
> How about if someone has a field of type siginfo_t as an element of a
> struct? For example:
> 
> struct foo {
>   int x;
>   siginfo_t y;
> };
> 
> With this change wouldn't the y field move from offset 4 to offset 8?

This is a problem if such a struct is part of the ABI -- in the kernel I
found these that might be problematic:

| arch/csky/kernel/signal.c:struct rt_sigframe {
| arch/csky/kernel/signal.c-	/*
| arch/csky/kernel/signal.c-	 * pad[3] is compatible with the same struct defined in
| arch/csky/kernel/signal.c-	 * gcc/libgcc/config/csky/linux-unwind.h
| arch/csky/kernel/signal.c-	 */
| arch/csky/kernel/signal.c-	int pad[3];
| arch/csky/kernel/signal.c-	struct siginfo info;
| arch/csky/kernel/signal.c-	struct ucontext uc;
| arch/csky/kernel/signal.c-};
| [...]
| arch/parisc/include/asm/rt_sigframe.h-#define SIGRETURN_TRAMP 4
| arch/parisc/include/asm/rt_sigframe.h-#define SIGRESTARTBLOCK_TRAMP 5 
| arch/parisc/include/asm/rt_sigframe.h-#define TRAMP_SIZE (SIGRETURN_TRAMP + SIGRESTARTBLOCK_TRAMP)
| arch/parisc/include/asm/rt_sigframe.h-
| arch/parisc/include/asm/rt_sigframe.h:struct rt_sigframe {
| arch/parisc/include/asm/rt_sigframe.h-	/* XXX: Must match trampoline size in arch/parisc/kernel/signal.c 
| arch/parisc/include/asm/rt_sigframe.h-	        Secondary to that it must protect the ERESTART_RESTARTBLOCK
| arch/parisc/include/asm/rt_sigframe.h-		trampoline we left on the stack (we were bad and didn't 
| arch/parisc/include/asm/rt_sigframe.h-		change sp so we could run really fast.) */
| arch/parisc/include/asm/rt_sigframe.h-	unsigned int tramp[TRAMP_SIZE];
| arch/parisc/include/asm/rt_sigframe.h-	struct siginfo info;
| [..]
| arch/parisc/kernel/signal32.h-#define COMPAT_SIGRETURN_TRAMP 4
| arch/parisc/kernel/signal32.h-#define COMPAT_SIGRESTARTBLOCK_TRAMP 5
| arch/parisc/kernel/signal32.h-#define COMPAT_TRAMP_SIZE (COMPAT_SIGRETURN_TRAMP + \
| arch/parisc/kernel/signal32.h-				COMPAT_SIGRESTARTBLOCK_TRAMP)
| arch/parisc/kernel/signal32.h-
| arch/parisc/kernel/signal32.h:struct compat_rt_sigframe {
| arch/parisc/kernel/signal32.h-        /* XXX: Must match trampoline size in arch/parisc/kernel/signal.c
| arch/parisc/kernel/signal32.h-                Secondary to that it must protect the ERESTART_RESTARTBLOCK
| arch/parisc/kernel/signal32.h-                trampoline we left on the stack (we were bad and didn't
| arch/parisc/kernel/signal32.h-                change sp so we could run really fast.) */
| arch/parisc/kernel/signal32.h-        compat_uint_t tramp[COMPAT_TRAMP_SIZE];
| arch/parisc/kernel/signal32.h-        compat_siginfo_t info;

Adding these static asserts to parisc shows the problem:

| diff --git a/arch/parisc/kernel/signal.c b/arch/parisc/kernel/signal.c
| index fb1e94a3982b..0be582fb81be 100644
| --- a/arch/parisc/kernel/signal.c
| +++ b/arch/parisc/kernel/signal.c
| @@ -610,3 +610,6 @@ void do_notify_resume(struct pt_regs *regs, long in_syscall)
|  	if (test_thread_flag(TIF_NOTIFY_RESUME))
|  		tracehook_notify_resume(regs);
|  }
| +
| +static_assert(sizeof(unsigned long) == 4); // 32 bit build
| +static_assert(offsetof(struct rt_sigframe, info) == 9 * 4);

This passes without the siginfo rework in this patch. With it:

| ./include/linux/build_bug.h:78:41: error: static assertion failed: "offsetof(struct rt_sigframe, info) == 9 * 4"

As sad as it is, I don't think we can have our cake and eat it, too. :-(

Unless you see why this is fine, I think we need to drop this patch and
go back to the simpler version you had.

Thanks,
-- Marco

Re: [PATCH 10/12] signal: Redefine signinfo so 64bit fields are possible

[Eric W. Biederman]

Marco Elver <elver@google.com> writes:

> On Mon, May 03, 2021 at 09:03PM -0700, Peter Collingbourne wrote:
>> On Mon, May 3, 2021 at 8:42 PM Eric W. Biederman <ebiederm@xmission.com> wrote:
>> > Marco Elver <elver@google.com> writes:
>> > > On Mon, 3 May 2021 at 23:04, Eric W. Biederman <ebiederm@xmission.com> wrote:
>> > >> "Eric W. Beiderman" <ebiederm@xmission.com> writes:
>> > >> > From: "Eric W. Biederman" <ebiederm@xmission.com>
>> > >> >
>> > >> > The si_perf code really wants to add a u64 field.  This change enables
>> > >> > that by reorganizing the definition of siginfo_t, so that a 64bit
>> > >> > field can be added without increasing the alignment of other fields.
>> > >
>> > > If you can, it'd be good to have an explanation for this, because it's
>> > > not at all obvious -- some future archeologist will wonder how we ever
>> > > came up with this definition of siginfo...
>> > >
>> > > (I see the trick here is that before the union would have changed
>> > > alignment, introducing padding after the 3 ints -- but now because the
>> > > 3 ints are inside the union the union's padding no longer adds padding
>> > > for these ints.  Perhaps you can explain it better than I can. Also
>> > > see below.)
>> >
>> > Yes.  The big idea is adding a 64bit field into the second union
>> > in the _sigfault case will increase the alignment of that second
>> > union to 64bit.
>> >
>> > In the 64bit case the alignment is already 64bit so it is not an
>> > issue.
>> >
>> > In the 32bit case there are 3 ints followed by a pointer.  When the
>> > 64bit member is added the alignment of _segfault becomes 64bit.  That
>> > 64bit alignment after 3 ints changes the location of the 32bit pointer.
>> >
>> > By moving the 3 preceding ints into _segfault that does not happen.
>> >
>> >
>> >
>> > There remains one very subtle issue that I think isn't a problem
>> > but I would appreciate someone else double checking me.
>> >
>> >
>> > The old definition of siginfo_t on 32bit almost certainly had 32bit
>> > alignment.  With the addition of a 64bit member siginfo_t gains 64bit
>> > alignment.  This difference only matters if the 64bit field is accessed.
>> > Accessing a 64bit field with 32bit alignment will cause unaligned access
>> > exceptions on some (most?) architectures.
>> >
>> > For the 64bit field to be accessed the code needs to be recompiled with
>> > the new headers.  Which implies that when everything is recompiled
>> > siginfo_t will become 64bit aligned.
>> >
>> >
>> > So the change should be safe unless someone is casting something with
>> > 32bit alignment into siginfo_t.
>> 
>> How about if someone has a field of type siginfo_t as an element of a
>> struct? For example:
>> 
>> struct foo {
>>   int x;
>>   siginfo_t y;
>> };
>> 
>> With this change wouldn't the y field move from offset 4 to offset 8?
>
> This is a problem if such a struct is part of the ABI -- in the kernel I
> found these that might be problematic:
>
> | arch/csky/kernel/signal.c:struct rt_sigframe {
> | arch/csky/kernel/signal.c-	/*
> | arch/csky/kernel/signal.c-	 * pad[3] is compatible with the same struct defined in
> | arch/csky/kernel/signal.c-	 * gcc/libgcc/config/csky/linux-unwind.h
> | arch/csky/kernel/signal.c-	 */
> | arch/csky/kernel/signal.c-	int pad[3];
> | arch/csky/kernel/signal.c-	struct siginfo info;
> | arch/csky/kernel/signal.c-	struct ucontext uc;
> | arch/csky/kernel/signal.c-};
> | [...]
> | arch/parisc/include/asm/rt_sigframe.h-#define SIGRETURN_TRAMP 4
> | arch/parisc/include/asm/rt_sigframe.h-#define SIGRESTARTBLOCK_TRAMP 5 
> | arch/parisc/include/asm/rt_sigframe.h-#define TRAMP_SIZE (SIGRETURN_TRAMP + SIGRESTARTBLOCK_TRAMP)
> | arch/parisc/include/asm/rt_sigframe.h-
> | arch/parisc/include/asm/rt_sigframe.h:struct rt_sigframe {
> | arch/parisc/include/asm/rt_sigframe.h-	/* XXX: Must match trampoline size in arch/parisc/kernel/signal.c 
> | arch/parisc/include/asm/rt_sigframe.h-	        Secondary to that it must protect the ERESTART_RESTARTBLOCK
> | arch/parisc/include/asm/rt_sigframe.h-		trampoline we left on the stack (we were bad and didn't 
> | arch/parisc/include/asm/rt_sigframe.h-		change sp so we could run really fast.) */
> | arch/parisc/include/asm/rt_sigframe.h-	unsigned int tramp[TRAMP_SIZE];
> | arch/parisc/include/asm/rt_sigframe.h-	struct siginfo info;
> | [..]
> | arch/parisc/kernel/signal32.h-#define COMPAT_SIGRETURN_TRAMP 4
> | arch/parisc/kernel/signal32.h-#define COMPAT_SIGRESTARTBLOCK_TRAMP 5
> | arch/parisc/kernel/signal32.h-#define COMPAT_TRAMP_SIZE (COMPAT_SIGRETURN_TRAMP + \
> | arch/parisc/kernel/signal32.h-				COMPAT_SIGRESTARTBLOCK_TRAMP)
> | arch/parisc/kernel/signal32.h-
> | arch/parisc/kernel/signal32.h:struct compat_rt_sigframe {
> | arch/parisc/kernel/signal32.h-        /* XXX: Must match trampoline size in arch/parisc/kernel/signal.c
> | arch/parisc/kernel/signal32.h-                Secondary to that it must protect the ERESTART_RESTARTBLOCK
> | arch/parisc/kernel/signal32.h-                trampoline we left on the stack (we were bad and didn't
> | arch/parisc/kernel/signal32.h-                change sp so we could run really fast.) */
> | arch/parisc/kernel/signal32.h-        compat_uint_t tramp[COMPAT_TRAMP_SIZE];
> | arch/parisc/kernel/signal32.h-        compat_siginfo_t info;
>
> Adding these static asserts to parisc shows the problem:
>
> | diff --git a/arch/parisc/kernel/signal.c b/arch/parisc/kernel/signal.c
> | index fb1e94a3982b..0be582fb81be 100644
> | --- a/arch/parisc/kernel/signal.c
> | +++ b/arch/parisc/kernel/signal.c
> | @@ -610,3 +610,6 @@ void do_notify_resume(struct pt_regs *regs, long in_syscall)
> |  	if (test_thread_flag(TIF_NOTIFY_RESUME))
> |  		tracehook_notify_resume(regs);
> |  }
> | +
> | +static_assert(sizeof(unsigned long) == 4); // 32 bit build
> | +static_assert(offsetof(struct rt_sigframe, info) == 9 * 4);
>
> This passes without the siginfo rework in this patch. With it:
>
> | ./include/linux/build_bug.h:78:41: error: static assertion failed: "offsetof(struct rt_sigframe, info) == 9 * 4"
>
> As sad as it is, I don't think we can have our cake and eat it, too. :-(
>
> Unless you see why this is fine, I think we need to drop this patch and
> go back to the simpler version you had.

No.  I really can't.  I think we are stuck with 32bit alignment on 32bit
architectures at this point.  Which precludes 32bit architectures from
including a 64bit field.

The variant of this that concerns me the most is siginfo_t embedded in a
structure in a library combined with code that is compiled with new
headers.  The offset of the embedded siginfo_t could very easily change
and break things.

That makes the alignment an ABI property we can't mess with.  Shame.

I will figure out some static asserts to verify this property remains
on 32bit and respin this series.

Eric

[PATCH 11/12] signal: Deliver all of the siginfo perf data in _perf

[Eric W. Beiderman]

From: "Eric W. Biederman" <ebiederm@xmission.com>

Don't abuse si_errno and deliver all of the perf data in _perf member
of siginfo_t.

Because it is possible increase the size of perf_data to 64bits.

v1: https://lkml.kernel.org/r/m11rarqqx2.fsf_-_@fess.ebiederm.org
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
---
 arch/arm/kernel/signal.c                      |  3 ++-
 arch/arm64/kernel/signal.c                    |  3 ++-
 arch/arm64/kernel/signal32.c                  |  3 ++-
 arch/sparc/kernel/signal32.c                  |  3 ++-
 arch/sparc/kernel/signal_64.c                 |  3 ++-
 arch/x86/kernel/signal_compat.c               |  8 ++++---
 fs/signalfd.c                                 |  3 ++-
 include/linux/compat.h                        |  5 ++++-
 include/uapi/asm-generic/siginfo.h            |  8 +++++--
 include/uapi/linux/signalfd.h                 |  4 ++--
 kernel/signal.c                               | 21 ++++++++++++-------
 .../selftests/perf_events/sigtrap_threads.c   | 12 +++++------
 12 files changed, 48 insertions(+), 28 deletions(-)

diff --git a/arch/arm/kernel/signal.c b/arch/arm/kernel/signal.c
index 2dac5d2c5cf6..ffd3cb8dadea 100644
--- a/arch/arm/kernel/signal.c
+++ b/arch/arm/kernel/signal.c
@@ -755,7 +755,8 @@ static_assert(offsetof(siginfo_t, si_addr_lsb)	== 0x10);
 static_assert(offsetof(siginfo_t, si_lower)	== 0x14);
 static_assert(offsetof(siginfo_t, si_upper)	== 0x18);
 static_assert(offsetof(siginfo_t, si_pkey)	== 0x14);
-static_assert(offsetof(siginfo_t, si_perf)	== 0x10);
+static_assert(offsetof(siginfo_t, si_perf_data)	== 0x10);
+static_assert(offsetof(siginfo_t, si_perf_type)	== 0x18);
 static_assert(offsetof(siginfo_t, si_band)	== 0x0c);
 static_assert(offsetof(siginfo_t, si_fd)	== 0x10);
 static_assert(offsetof(siginfo_t, si_call_addr)	== 0x0c);
diff --git a/arch/arm64/kernel/signal.c b/arch/arm64/kernel/signal.c
index af8bd2af1298..f6cbbc54861e 100644
--- a/arch/arm64/kernel/signal.c
+++ b/arch/arm64/kernel/signal.c
@@ -1003,7 +1003,8 @@ static_assert(offsetof(siginfo_t, si_addr_lsb)	== 0x18);
 static_assert(offsetof(siginfo_t, si_lower)	== 0x20);
 static_assert(offsetof(siginfo_t, si_upper)	== 0x28);
 static_assert(offsetof(siginfo_t, si_pkey)	== 0x20);
-static_assert(offsetof(siginfo_t, si_perf)	== 0x18);
+static_assert(offsetof(siginfo_t, si_perf_data)	== 0x18);
+static_assert(offsetof(siginfo_t, si_perf_type)	== 0x20);
 static_assert(offsetof(siginfo_t, si_band)	== 0x10);
 static_assert(offsetof(siginfo_t, si_fd)	== 0x18);
 static_assert(offsetof(siginfo_t, si_call_addr)	== 0x10);
diff --git a/arch/arm64/kernel/signal32.c b/arch/arm64/kernel/signal32.c
index b6afb646515f..8241dcc43d7f 100644
--- a/arch/arm64/kernel/signal32.c
+++ b/arch/arm64/kernel/signal32.c
@@ -487,7 +487,8 @@ static_assert(offsetof(compat_siginfo_t, si_addr_lsb)	== 0x10);
 static_assert(offsetof(compat_siginfo_t, si_lower)	== 0x14);
 static_assert(offsetof(compat_siginfo_t, si_upper)	== 0x18);
 static_assert(offsetof(compat_siginfo_t, si_pkey)	== 0x14);
-static_assert(offsetof(compat_siginfo_t, si_perf)	== 0x10);
+static_assert(offsetof(compat_siginfo_t, si_perf_data)	== 0x10);
+static_assert(offsetof(compat_siginfo_t, si_perf_type)	== 0x18);
 static_assert(offsetof(compat_siginfo_t, si_band)	== 0x0c);
 static_assert(offsetof(compat_siginfo_t, si_fd)		== 0x10);
 static_assert(offsetof(compat_siginfo_t, si_call_addr)	== 0x0c);
diff --git a/arch/sparc/kernel/signal32.c b/arch/sparc/kernel/signal32.c
index 73fd8700df3e..1c8b60dd27d8 100644
--- a/arch/sparc/kernel/signal32.c
+++ b/arch/sparc/kernel/signal32.c
@@ -776,6 +776,7 @@ static_assert(offsetof(compat_siginfo_t, si_addr_lsb)	== 0x10);
 static_assert(offsetof(compat_siginfo_t, si_lower)	== 0x14);
 static_assert(offsetof(compat_siginfo_t, si_upper)	== 0x18);
 static_assert(offsetof(compat_siginfo_t, si_pkey)	== 0x14);
-static_assert(offsetof(compat_siginfo_t, si_perf)	== 0x10);
+static_assert(offsetof(compat_siginfo_t, si_perf_data)	== 0x10);
+static_assert(offsetof(compat_siginfo_t, si_perf_type)	== 0x18);
 static_assert(offsetof(compat_siginfo_t, si_band)	== 0x0c);
 static_assert(offsetof(compat_siginfo_t, si_fd)		== 0x10);
diff --git a/arch/sparc/kernel/signal_64.c b/arch/sparc/kernel/signal_64.c
index 17913daa66c6..a58e0cc45d24 100644
--- a/arch/sparc/kernel/signal_64.c
+++ b/arch/sparc/kernel/signal_64.c
@@ -586,6 +586,7 @@ static_assert(offsetof(siginfo_t, si_addr_lsb)	== 0x18);
 static_assert(offsetof(siginfo_t, si_lower)	== 0x20);
 static_assert(offsetof(siginfo_t, si_upper)	== 0x28);
 static_assert(offsetof(siginfo_t, si_pkey)	== 0x20);
-static_assert(offsetof(siginfo_t, si_perf)	== 0x18);
+static_assert(offsetof(siginfo_t, si_perf_data)	== 0x18);
+static_assert(offsetof(siginfo_t, si_perf_type)	== 0x20);
 static_assert(offsetof(siginfo_t, si_band)	== 0x10);
 static_assert(offsetof(siginfo_t, si_fd)	== 0x14);
diff --git a/arch/x86/kernel/signal_compat.c b/arch/x86/kernel/signal_compat.c
index a5cd01c52dfb..a81310fe9e8a 100644
--- a/arch/x86/kernel/signal_compat.c
+++ b/arch/x86/kernel/signal_compat.c
@@ -118,7 +118,7 @@ static inline void signal_compat_build_tests(void)
 #endif
 
 	CHECK_CSI_OFFSET(_sigfault);
-	CHECK_CSI_SIZE  (_sigfault, 4*sizeof(int));
+	CHECK_CSI_SIZE  (_sigfault, 5*sizeof(int));
 	CHECK_SI_SIZE   (_sigfault, 8*sizeof(int));
 
 	BUILD_BUG_ON(offsetof(siginfo_t, si_addr) != 0x10);
@@ -138,8 +138,10 @@ static inline void signal_compat_build_tests(void)
 	BUILD_BUG_ON(offsetof(siginfo_t, si_pkey) != 0x20);
 	BUILD_BUG_ON(offsetof(compat_siginfo_t, si_pkey) != 0x14);
 
-	BUILD_BUG_ON(offsetof(siginfo_t, si_perf) != 0x18);
-	BUILD_BUG_ON(offsetof(compat_siginfo_t, si_perf) != 0x10);
+	BUILD_BUG_ON(offsetof(siginfo_t, si_perf_data) != 0x18);
+	BUILD_BUG_ON(offsetof(siginfo_t, si_perf_type) != 0x20);
+	BUILD_BUG_ON(offsetof(compat_siginfo_t, si_perf_data) != 0x10);
+	BUILD_BUG_ON(offsetof(compat_siginfo_t, si_perf_type) != 0x18);
 
 	CHECK_CSI_OFFSET(_sigpoll);
 	CHECK_CSI_SIZE  (_sigpoll, 2*sizeof(int));
diff --git a/fs/signalfd.c b/fs/signalfd.c
index 83130244f653..335ad39f3900 100644
--- a/fs/signalfd.c
+++ b/fs/signalfd.c
@@ -134,7 +134,8 @@ static int signalfd_copyinfo(struct signalfd_siginfo __user *uinfo,
 		break;
 	case SIL_FAULT_PERF_EVENT:
 		new.ssi_addr = (long) kinfo->si_addr;
-		new.ssi_perf = kinfo->si_perf;
+		new.ssi_perf_type = kinfo->si_perf_type;
+		new.ssi_perf_data = kinfo->si_perf_data;
 		break;
 	case SIL_CHLD:
 		new.ssi_pid    = kinfo->si_pid;
diff --git a/include/linux/compat.h b/include/linux/compat.h
index d81493248bf3..9190a1c2aac7 100644
--- a/include/linux/compat.h
+++ b/include/linux/compat.h
@@ -241,7 +241,10 @@ typedef struct compat_siginfo {
 					u32 _pkey;
 				} _addr_pkey;
 				/* used when si_code=TRAP_PERF */
-				compat_ulong_t _perf;
+				struct {
+					u64 _data;
+					u32 _type;
+				} _perf;
 			};
 		} _sigfault;
 
diff --git a/include/uapi/asm-generic/siginfo.h b/include/uapi/asm-generic/siginfo.h
index 1fcede623a73..dbe3dd90876f 100644
--- a/include/uapi/asm-generic/siginfo.h
+++ b/include/uapi/asm-generic/siginfo.h
@@ -112,7 +112,10 @@ union __sifields {
 				__u32 _pkey;
 			} _addr_pkey;
 			/* used when si_code=TRAP_PERF */
-			unsigned long _perf;
+			struct {
+				__u64 _data;
+				__u32 _type;
+			} _perf;
 		};
 	} _sigfault;
 
@@ -168,7 +171,8 @@ typedef struct siginfo {
 #define si_lower	_sifields._sigfault._addr_bnd._lower
 #define si_upper	_sifields._sigfault._addr_bnd._upper
 #define si_pkey		_sifields._sigfault._addr_pkey._pkey
-#define si_perf		_sifields._sigfault._perf
+#define si_perf_data	_sifields._sigfault._perf._data
+#define si_perf_type	_sifields._sigfault._perf._type
 #define si_band		_sifields._sigpoll._band
 #define si_fd		_sifields._sigpoll._fd
 #define si_call_addr	_sifields._sigsys._call_addr
diff --git a/include/uapi/linux/signalfd.h b/include/uapi/linux/signalfd.h
index 7e333042c7e3..e78dddf433fc 100644
--- a/include/uapi/linux/signalfd.h
+++ b/include/uapi/linux/signalfd.h
@@ -39,8 +39,8 @@ struct signalfd_siginfo {
 	__s32 ssi_syscall;
 	__u64 ssi_call_addr;
 	__u32 ssi_arch;
-	__u32 __pad3;
-	__u64 ssi_perf;
+	__u32 ssi_perf_type;
+	__u64 ssi_perf_data;
 
 	/*
 	 * Pad strcture to 128 bytes. Remember to update the
diff --git a/kernel/signal.c b/kernel/signal.c
index 49560ceac048..7fec9d1c5b11 100644
--- a/kernel/signal.c
+++ b/kernel/signal.c
@@ -1758,11 +1758,13 @@ int force_sig_perf(void __user *addr, u32 type, u64 sig_data)
 	struct kernel_siginfo info;
 
 	clear_siginfo(&info);
-	info.si_signo = SIGTRAP;
-	info.si_errno = type;
-	info.si_code  = TRAP_PERF;
-	info.si_addr  = addr;
-	info.si_perf  = sig_data;
+	info.si_signo     = SIGTRAP;
+	info.si_errno     = 0;
+	info.si_code      = TRAP_PERF;
+	info.si_addr      = addr;
+	info.si_perf_data = sig_data;
+	info.si_perf_type = type;
+
 	return force_sig_info(&info);
 }
 
@@ -3380,7 +3382,8 @@ void copy_siginfo_to_external32(struct compat_siginfo *to,
 		break;
 	case SIL_FAULT_PERF_EVENT:
 		to->si_addr = ptr_to_compat(from->si_addr);
-		to->si_perf = from->si_perf;
+		to->si_perf_data = from->si_perf_data;
+		to->si_perf_type = from->si_perf_type;
 		break;
 	case SIL_CHLD:
 		to->si_pid = from->si_pid;
@@ -3456,7 +3459,8 @@ static int post_copy_siginfo_from_user32(kernel_siginfo_t *to,
 		break;
 	case SIL_FAULT_PERF_EVENT:
 		to->si_addr = compat_ptr(from->si_addr);
-		to->si_perf = from->si_perf;
+		to->si_perf_data = from->si_perf_data;
+		to->si_perf_type = from->si_perf_type;
 		break;
 	case SIL_CHLD:
 		to->si_pid    = from->si_pid;
@@ -4639,7 +4643,8 @@ static inline void siginfo_buildtime_checks(void)
 	CHECK_OFFSET(si_lower);
 	CHECK_OFFSET(si_upper);
 	CHECK_OFFSET(si_pkey);
-	CHECK_OFFSET(si_perf);
+	CHECK_OFFSET(si_perf_data);
+	CHECK_OFFSET(si_perf_type);
 
 	/* sigpoll */
 	CHECK_OFFSET(si_band);
diff --git a/tools/testing/selftests/perf_events/sigtrap_threads.c b/tools/testing/selftests/perf_events/sigtrap_threads.c
index 78ddf5e11625..fde123066a8c 100644
--- a/tools/testing/selftests/perf_events/sigtrap_threads.c
+++ b/tools/testing/selftests/perf_events/sigtrap_threads.c
@@ -164,8 +164,8 @@ TEST_F(sigtrap_threads, enable_event)
 	EXPECT_EQ(ctx.signal_count, NUM_THREADS);
 	EXPECT_EQ(ctx.tids_want_signal, 0);
 	EXPECT_EQ(ctx.first_siginfo.si_addr, &ctx.iterate_on);
-	EXPECT_EQ(ctx.first_siginfo.si_errno, PERF_TYPE_BREAKPOINT);
-	EXPECT_EQ(ctx.first_siginfo.si_perf, TEST_SIG_DATA(&ctx.iterate_on));
+	EXPECT_EQ(ctx.first_siginfo.si_perf_type, PERF_TYPE_BREAKPOINT);
+	EXPECT_EQ(ctx.first_siginfo.si_perf_data, TEST_SIG_DATA(&ctx.iterate_on));
 
 	/* Check enabled for parent. */
 	ctx.iterate_on = 0;
@@ -183,8 +183,8 @@ TEST_F(sigtrap_threads, modify_and_enable_event)
 	EXPECT_EQ(ctx.signal_count, NUM_THREADS);
 	EXPECT_EQ(ctx.tids_want_signal, 0);
 	EXPECT_EQ(ctx.first_siginfo.si_addr, &ctx.iterate_on);
-	EXPECT_EQ(ctx.first_siginfo.si_errno, PERF_TYPE_BREAKPOINT);
-	EXPECT_EQ(ctx.first_siginfo.si_perf, TEST_SIG_DATA(&ctx.iterate_on));
+	EXPECT_EQ(ctx.first_siginfo.si_perf_type, PERF_TYPE_BREAKPOINT);
+	EXPECT_EQ(ctx.first_siginfo.si_perf_data, TEST_SIG_DATA(&ctx.iterate_on));
 
 	/* Check enabled for parent. */
 	ctx.iterate_on = 0;
@@ -203,8 +203,8 @@ TEST_F(sigtrap_threads, signal_stress)
 	EXPECT_EQ(ctx.signal_count, NUM_THREADS * ctx.iterate_on);
 	EXPECT_EQ(ctx.tids_want_signal, 0);
 	EXPECT_EQ(ctx.first_siginfo.si_addr, &ctx.iterate_on);
-	EXPECT_EQ(ctx.first_siginfo.si_errno, PERF_TYPE_BREAKPOINT);
-	EXPECT_EQ(ctx.first_siginfo.si_perf, TEST_SIG_DATA(&ctx.iterate_on));
+	EXPECT_EQ(ctx.first_siginfo.si_perf_type, PERF_TYPE_BREAKPOINT);
+	EXPECT_EQ(ctx.first_siginfo.si_perf_data, TEST_SIG_DATA(&ctx.iterate_on));
 }
 
 TEST_HARNESS_MAIN
-- 
2.30.1

[PATCH 12/12] signalfd: Remove SIL_FAULT_PERF_EVENT fields from signalfd_siginfo

[Eric W. Beiderman]

From: "Eric W. Biederman" <ebiederm@xmission.com>

With the addition of ssi_perf_data and ssi_perf_type struct signalfd_siginfo
is dangerously close to running out of space.  All that remains is just
enough space for two additional 64bit fields.  A practice of adding all
possible siginfo_t fields into struct singalfd_siginfo can not be supported
as adding the missing fields ssi_lower, ssi_upper, and ssi_pkey would
require two 64bit fields and one 32bit fields.  In practice the fields
ssi_perf_data and ssi_perf_type can never be used by signalfd as the signal
that generates them always delivers them synchronously to the thread that
triggers them.

Therefore until someone actually needs the fields ssi_perf_data and
ssi_perf_type in signalfd_siginfo remove them.  This leaves a bit more room
for future expansion.

Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
---
 fs/signalfd.c                 | 16 ++++++----------
 include/uapi/linux/signalfd.h |  4 +---
 2 files changed, 7 insertions(+), 13 deletions(-)

diff --git a/fs/signalfd.c b/fs/signalfd.c
index 335ad39f3900..040e1cf90528 100644
--- a/fs/signalfd.c
+++ b/fs/signalfd.c
@@ -114,12 +114,13 @@ static int signalfd_copyinfo(struct signalfd_siginfo __user *uinfo,
 		break;
 	case SIL_FAULT_BNDERR:
 	case SIL_FAULT_PKUERR:
+	case SIL_FAULT_PERF_EVENT:
 		/*
-		 * Fall through to the SIL_FAULT case.  Both SIL_FAULT_BNDERR
-		 * and SIL_FAULT_PKUERR are only generated by faults that
-		 * deliver them synchronously to userspace.  In case someone
-		 * injects one of these signals and signalfd catches it treat
-		 * it as SIL_FAULT.
+		 * Fall through to the SIL_FAULT case.  SIL_FAULT_BNDERR,
+		 * SIL_FAULT_PKUERR, and SIL_FAULT_PERF_EVENT are only
+		 * generated by faults that deliver them synchronously to
+		 * userspace.  In case someone injects one of these signals
+		 * and signalfd catches it treat it as SIL_FAULT.
 		 */
 	case SIL_FAULT:
 		new.ssi_addr = (long) kinfo->si_addr;
@@ -132,11 +133,6 @@ static int signalfd_copyinfo(struct signalfd_siginfo __user *uinfo,
 		new.ssi_addr = (long) kinfo->si_addr;
 		new.ssi_addr_lsb = (short) kinfo->si_addr_lsb;
 		break;
-	case SIL_FAULT_PERF_EVENT:
-		new.ssi_addr = (long) kinfo->si_addr;
-		new.ssi_perf_type = kinfo->si_perf_type;
-		new.ssi_perf_data = kinfo->si_perf_data;
-		break;
 	case SIL_CHLD:
 		new.ssi_pid    = kinfo->si_pid;
 		new.ssi_uid    = kinfo->si_uid;
diff --git a/include/uapi/linux/signalfd.h b/include/uapi/linux/signalfd.h
index e78dddf433fc..83429a05b698 100644
--- a/include/uapi/linux/signalfd.h
+++ b/include/uapi/linux/signalfd.h
@@ -39,8 +39,6 @@ struct signalfd_siginfo {
 	__s32 ssi_syscall;
 	__u64 ssi_call_addr;
 	__u32 ssi_arch;
-	__u32 ssi_perf_type;
-	__u64 ssi_perf_data;
 
 	/*
 	 * Pad strcture to 128 bytes. Remember to update the
@@ -51,7 +49,7 @@ struct signalfd_siginfo {
 	 * comes out of a read(2) and we really don't want to have
 	 * a compat on read(2).
 	 */
-	__u8 __pad[16];
+	__u8 __pad[28];
 };
 
 
-- 
2.30.1

[PATCH v3 00/12] signal: sort out si_trapno and si_perf

[Eric W. Biederman]

This set of changes sorts out the ABI issues with SIGTRAP TRAP_PERF, and
hopefully will can get merged before any userspace code starts using the
new ABI.

The big ideas are:
- Placing the asserts first to prevent unexpected ABI changes
- si_trapno becomming ordinary fault subfield.
- struct signalfd_siginfo is almost full

This set of changes starts out with Marco's static_assert changes and
additional one of my own that enforces the fact that the alignment of
siginfo_t is also part of the ABI.  Together these build time
checks verify there are no unexpected ABI changes in the changes
that follow.

The field si_trapno is changed to become an ordinary extension of the
_sigfault member of siginfo.

The code is refactored a bit and then si_perf_type is added along side
si_perf_data in the _perf subfield of _sigfault of siginfo_t.

Finally the signalfd_siginfo fields are removed as they appear to be
filling up the structure without userspace actually being able to use
them.

v2: https://lkml.kernel.org/r/m14kfjh8et.fsf_-_@fess.ebiederm.org
v1: https://lkml.kernel.org/r/m1zgxfs7zq.fsf_-_@fess.ebiederm.org

Eric W. Biederman (9):
      signal: Verify the alignment and size of siginfo_t
      siginfo: Move si_trapno inside the union inside _si_fault
      signal: Implement SIL_FAULT_TRAPNO
      signal: Use dedicated helpers to send signals with si_trapno set
      signal: Remove __ARCH_SI_TRAPNO
      signal: Rename SIL_PERF_EVENT SIL_FAULT_PERF_EVENT for consistency
      signal: Factor force_sig_perf out of perf_sigtrap
      signal: Deliver all of the siginfo perf data in _perf
      signalfd: Remove SIL_FAULT_PERF_EVENT fields from signalfd_siginfo

Marco Elver (3):
      sparc64: Add compile-time asserts for siginfo_t offsets
      arm: Add compile-time asserts for siginfo_t offsets
      arm64: Add compile-time asserts for siginfo_t offsets

 arch/alpha/include/uapi/asm/siginfo.h              |   2 -
 arch/alpha/kernel/osf_sys.c                        |   2 +-
 arch/alpha/kernel/signal.c                         |   4 +-
 arch/alpha/kernel/traps.c                          |  24 ++---
 arch/alpha/mm/fault.c                              |   4 +-
 arch/arm/kernel/signal.c                           |  39 +++++++
 arch/arm64/kernel/signal.c                         |  39 +++++++
 arch/arm64/kernel/signal32.c                       |  39 +++++++
 arch/mips/include/uapi/asm/siginfo.h               |   2 -
 arch/sparc/include/uapi/asm/siginfo.h              |   3 -
 arch/sparc/kernel/process_64.c                     |   2 +-
 arch/sparc/kernel/signal32.c                       |  37 +++++++
 arch/sparc/kernel/signal_64.c                      |  36 +++++++
 arch/sparc/kernel/sys_sparc_32.c                   |   2 +-
 arch/sparc/kernel/sys_sparc_64.c                   |   2 +-
 arch/sparc/kernel/traps_32.c                       |  22 ++--
 arch/sparc/kernel/traps_64.c                       |  44 ++++----
 arch/sparc/kernel/unaligned_32.c                   |   2 +-
 arch/sparc/mm/fault_32.c                           |   2 +-
 arch/sparc/mm/fault_64.c                           |   2 +-
 arch/x86/kernel/signal_compat.c                    |  15 ++-
 fs/signalfd.c                                      |  23 ++---
 include/linux/compat.h                             |  10 +-
 include/linux/sched/signal.h                       |  13 +--
 include/linux/signal.h                             |   3 +-
 include/uapi/asm-generic/siginfo.h                 |  20 ++--
 include/uapi/linux/signalfd.h                      |   4 +-
 kernel/events/core.c                               |  11 +-
 kernel/signal.c                                    | 113 +++++++++++++--------
 .../selftests/perf_events/sigtrap_threads.c        |  12 +--
 30 files changed, 373 insertions(+), 160 deletions(-)

Re: [PATCH v3 00/12] signal: sort out si_trapno and si_perf

[Marco Elver]

On Tue, 4 May 2021 at 23:13, Eric W. Biederman <ebiederm@xmission.com> wrote:
>
> This set of changes sorts out the ABI issues with SIGTRAP TRAP_PERF, and
> hopefully will can get merged before any userspace code starts using the
> new ABI.
>
> The big ideas are:
> - Placing the asserts first to prevent unexpected ABI changes
> - si_trapno becomming ordinary fault subfield.
> - struct signalfd_siginfo is almost full
>
> This set of changes starts out with Marco's static_assert changes and
> additional one of my own that enforces the fact that the alignment of
> siginfo_t is also part of the ABI.  Together these build time
> checks verify there are no unexpected ABI changes in the changes
> that follow.
>
> The field si_trapno is changed to become an ordinary extension of the
> _sigfault member of siginfo.
>
> The code is refactored a bit and then si_perf_type is added along side
> si_perf_data in the _perf subfield of _sigfault of siginfo_t.
>
> Finally the signalfd_siginfo fields are removed as they appear to be
> filling up the structure without userspace actually being able to use
> them.
>
> v2: https://lkml.kernel.org/r/m14kfjh8et.fsf_-_@fess.ebiederm.org
> v1: https://lkml.kernel.org/r/m1zgxfs7zq.fsf_-_@fess.ebiederm.org
>
> Eric W. Biederman (9):
>       signal: Verify the alignment and size of siginfo_t
>       siginfo: Move si_trapno inside the union inside _si_fault
>       signal: Implement SIL_FAULT_TRAPNO
>       signal: Use dedicated helpers to send signals with si_trapno set
>       signal: Remove __ARCH_SI_TRAPNO
>       signal: Rename SIL_PERF_EVENT SIL_FAULT_PERF_EVENT for consistency
>       signal: Factor force_sig_perf out of perf_sigtrap
>       signal: Deliver all of the siginfo perf data in _perf
>       signalfd: Remove SIL_FAULT_PERF_EVENT fields from signalfd_siginfo
>
> Marco Elver (3):
>       sparc64: Add compile-time asserts for siginfo_t offsets
>       arm: Add compile-time asserts for siginfo_t offsets
>       arm64: Add compile-time asserts for siginfo_t offsets

I can't seem to see the rest of them in my inbox. LKML also is missing
them: https://lore.kernel.org/linux-api/m1tuni8ano.fsf_-_@fess.ebiederm.org/

Something must have swallowed them. Could you resend?
I'll then test in the morning.

Thanks,
-- Marco

Re: [PATCH v3 00/12] signal: sort out si_trapno and si_perf

[Eric W. Biederman]

Marco Elver <elver@google.com> writes:

> On Tue, 4 May 2021 at 23:13, Eric W. Biederman <ebiederm@xmission.com> wrote:
>>
>> This set of changes sorts out the ABI issues with SIGTRAP TRAP_PERF, and
>> hopefully will can get merged before any userspace code starts using the
>> new ABI.
>>
>> The big ideas are:
>> - Placing the asserts first to prevent unexpected ABI changes
>> - si_trapno becomming ordinary fault subfield.
>> - struct signalfd_siginfo is almost full
>>
>> This set of changes starts out with Marco's static_assert changes and
>> additional one of my own that enforces the fact that the alignment of
>> siginfo_t is also part of the ABI.  Together these build time
>> checks verify there are no unexpected ABI changes in the changes
>> that follow.
>>
>> The field si_trapno is changed to become an ordinary extension of the
>> _sigfault member of siginfo.
>>
>> The code is refactored a bit and then si_perf_type is added along side
>> si_perf_data in the _perf subfield of _sigfault of siginfo_t.
>>
>> Finally the signalfd_siginfo fields are removed as they appear to be
>> filling up the structure without userspace actually being able to use
>> them.
>>
>> v2: https://lkml.kernel.org/r/m14kfjh8et.fsf_-_@fess.ebiederm.org
>> v1: https://lkml.kernel.org/r/m1zgxfs7zq.fsf_-_@fess.ebiederm.org
>>
>> Eric W. Biederman (9):
>>       signal: Verify the alignment and size of siginfo_t
>>       siginfo: Move si_trapno inside the union inside _si_fault
>>       signal: Implement SIL_FAULT_TRAPNO
>>       signal: Use dedicated helpers to send signals with si_trapno set
>>       signal: Remove __ARCH_SI_TRAPNO
>>       signal: Rename SIL_PERF_EVENT SIL_FAULT_PERF_EVENT for consistency
>>       signal: Factor force_sig_perf out of perf_sigtrap
>>       signal: Deliver all of the siginfo perf data in _perf
>>       signalfd: Remove SIL_FAULT_PERF_EVENT fields from signalfd_siginfo
>>
>> Marco Elver (3):
>>       sparc64: Add compile-time asserts for siginfo_t offsets
>>       arm: Add compile-time asserts for siginfo_t offsets
>>       arm64: Add compile-time asserts for siginfo_t offsets
>
> I can't seem to see the rest of them in my inbox. LKML also is missing
> them: https://lore.kernel.org/linux-api/m1tuni8ano.fsf_-_@fess.ebiederm.org/
>
> Something must have swallowed them. Could you resend?
> I'll then test in the morning.

They got stuck going out you should see them any time now.
Sorry about that.

Eric

[PATCH v3 01/12] sparc64: Add compile-time asserts for siginfo_t offsets

[Eric W. Beiderman]

From: Marco Elver <elver@google.com>

To help catch ABI breaks at compile-time, add compile-time assertions to
verify the siginfo_t layout. Unlike other architectures, sparc64 is
special, because it is one of few architectures requiring si_trapno.
ABI breaks around that field would only be caught here.

Link: https://lkml.kernel.org/r/m11rat9f85.fsf@fess.ebiederm.org
Suggested-by: Eric W. Biederman <ebiederm@xmission.com>
Acked-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Marco Elver <elver@google.com>
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
---
 arch/sparc/kernel/signal32.c  | 34 ++++++++++++++++++++++++++++++++++
 arch/sparc/kernel/signal_64.c | 33 +++++++++++++++++++++++++++++++++
 2 files changed, 67 insertions(+)

diff --git a/arch/sparc/kernel/signal32.c b/arch/sparc/kernel/signal32.c
index e9695a06492f..778ed5c26d4a 100644
--- a/arch/sparc/kernel/signal32.c
+++ b/arch/sparc/kernel/signal32.c
@@ -745,3 +745,37 @@ asmlinkage int do_sys32_sigstack(u32 u_ssptr, u32 u_ossptr, unsigned long sp)
 out:
 	return ret;
 }
+
+/*
+ * Compile-time assertions for siginfo_t offsets. Check NSIG* as well, as
+ * changes likely come with new fields that should be added below.
+ */
+static_assert(NSIGILL	== 11);
+static_assert(NSIGFPE	== 15);
+static_assert(NSIGSEGV	== 9);
+static_assert(NSIGBUS	== 5);
+static_assert(NSIGTRAP	== 6);
+static_assert(NSIGCHLD	== 6);
+static_assert(NSIGSYS	== 2);
+static_assert(offsetof(compat_siginfo_t, si_signo)	== 0x00);
+static_assert(offsetof(compat_siginfo_t, si_errno)	== 0x04);
+static_assert(offsetof(compat_siginfo_t, si_code)	== 0x08);
+static_assert(offsetof(compat_siginfo_t, si_pid)	== 0x0c);
+static_assert(offsetof(compat_siginfo_t, si_uid)	== 0x10);
+static_assert(offsetof(compat_siginfo_t, si_tid)	== 0x0c);
+static_assert(offsetof(compat_siginfo_t, si_overrun)	== 0x10);
+static_assert(offsetof(compat_siginfo_t, si_status)	== 0x14);
+static_assert(offsetof(compat_siginfo_t, si_utime)	== 0x18);
+static_assert(offsetof(compat_siginfo_t, si_stime)	== 0x1c);
+static_assert(offsetof(compat_siginfo_t, si_value)	== 0x14);
+static_assert(offsetof(compat_siginfo_t, si_int)	== 0x14);
+static_assert(offsetof(compat_siginfo_t, si_ptr)	== 0x14);
+static_assert(offsetof(compat_siginfo_t, si_addr)	== 0x0c);
+static_assert(offsetof(compat_siginfo_t, si_trapno)	== 0x10);
+static_assert(offsetof(compat_siginfo_t, si_addr_lsb)	== 0x14);
+static_assert(offsetof(compat_siginfo_t, si_lower)	== 0x18);
+static_assert(offsetof(compat_siginfo_t, si_upper)	== 0x1c);
+static_assert(offsetof(compat_siginfo_t, si_pkey)	== 0x18);
+static_assert(offsetof(compat_siginfo_t, si_perf)	== 0x14);
+static_assert(offsetof(compat_siginfo_t, si_band)	== 0x0c);
+static_assert(offsetof(compat_siginfo_t, si_fd)		== 0x10);
diff --git a/arch/sparc/kernel/signal_64.c b/arch/sparc/kernel/signal_64.c
index a0eec62c825d..c9bbf5f29078 100644
--- a/arch/sparc/kernel/signal_64.c
+++ b/arch/sparc/kernel/signal_64.c
@@ -556,3 +556,36 @@ void do_notify_resume(struct pt_regs *regs, unsigned long orig_i0, unsigned long
 	user_enter();
 }
 
+/*
+ * Compile-time assertions for siginfo_t offsets. Check NSIG* as well, as
+ * changes likely come with new fields that should be added below.
+ */
+static_assert(NSIGILL	== 11);
+static_assert(NSIGFPE	== 15);
+static_assert(NSIGSEGV	== 9);
+static_assert(NSIGBUS	== 5);
+static_assert(NSIGTRAP	== 6);
+static_assert(NSIGCHLD	== 6);
+static_assert(NSIGSYS	== 2);
+static_assert(offsetof(siginfo_t, si_signo)	== 0x00);
+static_assert(offsetof(siginfo_t, si_errno)	== 0x04);
+static_assert(offsetof(siginfo_t, si_code)	== 0x08);
+static_assert(offsetof(siginfo_t, si_pid)	== 0x10);
+static_assert(offsetof(siginfo_t, si_uid)	== 0x14);
+static_assert(offsetof(siginfo_t, si_tid)	== 0x10);
+static_assert(offsetof(siginfo_t, si_overrun)	== 0x14);
+static_assert(offsetof(siginfo_t, si_status)	== 0x18);
+static_assert(offsetof(siginfo_t, si_utime)	== 0x20);
+static_assert(offsetof(siginfo_t, si_stime)	== 0x28);
+static_assert(offsetof(siginfo_t, si_value)	== 0x18);
+static_assert(offsetof(siginfo_t, si_int)	== 0x18);
+static_assert(offsetof(siginfo_t, si_ptr)	== 0x18);
+static_assert(offsetof(siginfo_t, si_addr)	== 0x10);
+static_assert(offsetof(siginfo_t, si_trapno)	== 0x18);
+static_assert(offsetof(siginfo_t, si_addr_lsb)	== 0x20);
+static_assert(offsetof(siginfo_t, si_lower)	== 0x28);
+static_assert(offsetof(siginfo_t, si_upper)	== 0x30);
+static_assert(offsetof(siginfo_t, si_pkey)	== 0x28);
+static_assert(offsetof(siginfo_t, si_perf)	== 0x20);
+static_assert(offsetof(siginfo_t, si_band)	== 0x10);
+static_assert(offsetof(siginfo_t, si_fd)	== 0x14);
-- 
2.30.1

[PATCH v3 02/12] arm: Add compile-time asserts for siginfo_t offsets

[Eric W. Beiderman]

From: Marco Elver <elver@google.com>

To help catch ABI breaks at compile-time, add compile-time assertions to
verify the siginfo_t layout.

This could have caught that we cannot portably add 64-bit integers to
siginfo_t on 32-bit architectures like Arm before reaching -next:
https://lkml.kernel.org/r/20210422191823.79012-1-elver@google.com

Signed-off-by: Marco Elver <elver@google.com>
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
---
 arch/arm/kernel/signal.c | 36 ++++++++++++++++++++++++++++++++++++
 1 file changed, 36 insertions(+)

diff --git a/arch/arm/kernel/signal.c b/arch/arm/kernel/signal.c
index a3a38d0a4c85..2dac5d2c5cf6 100644
--- a/arch/arm/kernel/signal.c
+++ b/arch/arm/kernel/signal.c
@@ -725,3 +725,39 @@ asmlinkage void do_rseq_syscall(struct pt_regs *regs)
 	rseq_syscall(regs);
 }
 #endif
+
+/*
+ * Compile-time assertions for siginfo_t offsets. Check NSIG* as well, as
+ * changes likely come with new fields that should be added below.
+ */
+static_assert(NSIGILL	== 11);
+static_assert(NSIGFPE	== 15);
+static_assert(NSIGSEGV	== 9);
+static_assert(NSIGBUS	== 5);
+static_assert(NSIGTRAP	== 6);
+static_assert(NSIGCHLD	== 6);
+static_assert(NSIGSYS	== 2);
+static_assert(offsetof(siginfo_t, si_signo)	== 0x00);
+static_assert(offsetof(siginfo_t, si_errno)	== 0x04);
+static_assert(offsetof(siginfo_t, si_code)	== 0x08);
+static_assert(offsetof(siginfo_t, si_pid)	== 0x0c);
+static_assert(offsetof(siginfo_t, si_uid)	== 0x10);
+static_assert(offsetof(siginfo_t, si_tid)	== 0x0c);
+static_assert(offsetof(siginfo_t, si_overrun)	== 0x10);
+static_assert(offsetof(siginfo_t, si_status)	== 0x14);
+static_assert(offsetof(siginfo_t, si_utime)	== 0x18);
+static_assert(offsetof(siginfo_t, si_stime)	== 0x1c);
+static_assert(offsetof(siginfo_t, si_value)	== 0x14);
+static_assert(offsetof(siginfo_t, si_int)	== 0x14);
+static_assert(offsetof(siginfo_t, si_ptr)	== 0x14);
+static_assert(offsetof(siginfo_t, si_addr)	== 0x0c);
+static_assert(offsetof(siginfo_t, si_addr_lsb)	== 0x10);
+static_assert(offsetof(siginfo_t, si_lower)	== 0x14);
+static_assert(offsetof(siginfo_t, si_upper)	== 0x18);
+static_assert(offsetof(siginfo_t, si_pkey)	== 0x14);
+static_assert(offsetof(siginfo_t, si_perf)	== 0x10);
+static_assert(offsetof(siginfo_t, si_band)	== 0x0c);
+static_assert(offsetof(siginfo_t, si_fd)	== 0x10);
+static_assert(offsetof(siginfo_t, si_call_addr)	== 0x0c);
+static_assert(offsetof(siginfo_t, si_syscall)	== 0x10);
+static_assert(offsetof(siginfo_t, si_arch)	== 0x14);
-- 
2.30.1

[PATCH v3 03/12] arm64: Add compile-time asserts for siginfo_t offsets

[Eric W. Beiderman]

From: Marco Elver <elver@google.com>

To help catch ABI breaks at compile-time, add compile-time assertions to
verify the siginfo_t layout.

Signed-off-by: Marco Elver <elver@google.com>
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
---
 arch/arm64/kernel/signal.c   | 36 ++++++++++++++++++++++++++++++++++++
 arch/arm64/kernel/signal32.c | 36 ++++++++++++++++++++++++++++++++++++
 2 files changed, 72 insertions(+)

diff --git a/arch/arm64/kernel/signal.c b/arch/arm64/kernel/signal.c
index 6237486ff6bb..af8bd2af1298 100644
--- a/arch/arm64/kernel/signal.c
+++ b/arch/arm64/kernel/signal.c
@@ -973,3 +973,39 @@ void __init minsigstksz_setup(void)
 		round_up(sizeof(struct frame_record), 16) +
 		16; /* max alignment padding */
 }
+
+/*
+ * Compile-time assertions for siginfo_t offsets. Check NSIG* as well, as
+ * changes likely come with new fields that should be added below.
+ */
+static_assert(NSIGILL	== 11);
+static_assert(NSIGFPE	== 15);
+static_assert(NSIGSEGV	== 9);
+static_assert(NSIGBUS	== 5);
+static_assert(NSIGTRAP	== 6);
+static_assert(NSIGCHLD	== 6);
+static_assert(NSIGSYS	== 2);
+static_assert(offsetof(siginfo_t, si_signo)	== 0x00);
+static_assert(offsetof(siginfo_t, si_errno)	== 0x04);
+static_assert(offsetof(siginfo_t, si_code)	== 0x08);
+static_assert(offsetof(siginfo_t, si_pid)	== 0x10);
+static_assert(offsetof(siginfo_t, si_uid)	== 0x14);
+static_assert(offsetof(siginfo_t, si_tid)	== 0x10);
+static_assert(offsetof(siginfo_t, si_overrun)	== 0x14);
+static_assert(offsetof(siginfo_t, si_status)	== 0x18);
+static_assert(offsetof(siginfo_t, si_utime)	== 0x20);
+static_assert(offsetof(siginfo_t, si_stime)	== 0x28);
+static_assert(offsetof(siginfo_t, si_value)	== 0x18);
+static_assert(offsetof(siginfo_t, si_int)	== 0x18);
+static_assert(offsetof(siginfo_t, si_ptr)	== 0x18);
+static_assert(offsetof(siginfo_t, si_addr)	== 0x10);
+static_assert(offsetof(siginfo_t, si_addr_lsb)	== 0x18);
+static_assert(offsetof(siginfo_t, si_lower)	== 0x20);
+static_assert(offsetof(siginfo_t, si_upper)	== 0x28);
+static_assert(offsetof(siginfo_t, si_pkey)	== 0x20);
+static_assert(offsetof(siginfo_t, si_perf)	== 0x18);
+static_assert(offsetof(siginfo_t, si_band)	== 0x10);
+static_assert(offsetof(siginfo_t, si_fd)	== 0x18);
+static_assert(offsetof(siginfo_t, si_call_addr)	== 0x10);
+static_assert(offsetof(siginfo_t, si_syscall)	== 0x18);
+static_assert(offsetof(siginfo_t, si_arch)	== 0x1c);
diff --git a/arch/arm64/kernel/signal32.c b/arch/arm64/kernel/signal32.c
index 2f507f565c48..b6afb646515f 100644
--- a/arch/arm64/kernel/signal32.c
+++ b/arch/arm64/kernel/signal32.c
@@ -457,3 +457,39 @@ void compat_setup_restart_syscall(struct pt_regs *regs)
 {
        regs->regs[7] = __NR_compat_restart_syscall;
 }
+
+/*
+ * Compile-time assertions for siginfo_t offsets. Check NSIG* as well, as
+ * changes likely come with new fields that should be added below.
+ */
+static_assert(NSIGILL	== 11);
+static_assert(NSIGFPE	== 15);
+static_assert(NSIGSEGV	== 9);
+static_assert(NSIGBUS	== 5);
+static_assert(NSIGTRAP	== 6);
+static_assert(NSIGCHLD	== 6);
+static_assert(NSIGSYS	== 2);
+static_assert(offsetof(compat_siginfo_t, si_signo)	== 0x00);
+static_assert(offsetof(compat_siginfo_t, si_errno)	== 0x04);
+static_assert(offsetof(compat_siginfo_t, si_code)	== 0x08);
+static_assert(offsetof(compat_siginfo_t, si_pid)	== 0x0c);
+static_assert(offsetof(compat_siginfo_t, si_uid)	== 0x10);
+static_assert(offsetof(compat_siginfo_t, si_tid)	== 0x0c);
+static_assert(offsetof(compat_siginfo_t, si_overrun)	== 0x10);
+static_assert(offsetof(compat_siginfo_t, si_status)	== 0x14);
+static_assert(offsetof(compat_siginfo_t, si_utime)	== 0x18);
+static_assert(offsetof(compat_siginfo_t, si_stime)	== 0x1c);
+static_assert(offsetof(compat_siginfo_t, si_value)	== 0x14);
+static_assert(offsetof(compat_siginfo_t, si_int)	== 0x14);
+static_assert(offsetof(compat_siginfo_t, si_ptr)	== 0x14);
+static_assert(offsetof(compat_siginfo_t, si_addr)	== 0x0c);
+static_assert(offsetof(compat_siginfo_t, si_addr_lsb)	== 0x10);
+static_assert(offsetof(compat_siginfo_t, si_lower)	== 0x14);
+static_assert(offsetof(compat_siginfo_t, si_upper)	== 0x18);
+static_assert(offsetof(compat_siginfo_t, si_pkey)	== 0x14);
+static_assert(offsetof(compat_siginfo_t, si_perf)	== 0x10);
+static_assert(offsetof(compat_siginfo_t, si_band)	== 0x0c);
+static_assert(offsetof(compat_siginfo_t, si_fd)		== 0x10);
+static_assert(offsetof(compat_siginfo_t, si_call_addr)	== 0x0c);
+static_assert(offsetof(compat_siginfo_t, si_syscall)	== 0x10);
+static_assert(offsetof(compat_siginfo_t, si_arch)	== 0x14);
-- 
2.30.1

[PATCH v3 04/12] signal: Verify the alignment and size of siginfo_t

[Eric W. Beiderman]

From: "Eric W. Biederman" <ebiederm@xmission.com>

Update the static assertions about siginfo_t to also describe
it's alignment and size.

While investigating if it was possible to add a 64bit field into
siginfo_t[1] it became apparent that the alignment of siginfo_t
is as much a part of the ABI as the size of the structure.

If the alignment changes siginfo_t when embedded in another structure
can move to a different offset.  Which is not acceptable from an ABI
structure.

So document that fact and add static assertions to notify developers
if they change change the alignment by accident.

[1] https://lkml.kernel.org/r/YJEZdhe6JGFNYlum@elver.google.com
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
---
 arch/arm/kernel/signal.c           | 2 ++
 arch/arm64/kernel/signal.c         | 2 ++
 arch/arm64/kernel/signal32.c       | 2 ++
 arch/sparc/kernel/signal32.c       | 2 ++
 arch/sparc/kernel/signal_64.c      | 2 ++
 arch/x86/kernel/signal_compat.c    | 6 ++++++
 include/uapi/asm-generic/siginfo.h | 5 +++++
 7 files changed, 21 insertions(+)

diff --git a/arch/arm/kernel/signal.c b/arch/arm/kernel/signal.c
index 2dac5d2c5cf6..643bcb0f091b 100644
--- a/arch/arm/kernel/signal.c
+++ b/arch/arm/kernel/signal.c
@@ -737,6 +737,8 @@ static_assert(NSIGBUS	== 5);
 static_assert(NSIGTRAP	== 6);
 static_assert(NSIGCHLD	== 6);
 static_assert(NSIGSYS	== 2);
+static_assert(sizeof(siginfo_t) == 128);
+static_assert(__alignof__(siginfo_t) == 4);
 static_assert(offsetof(siginfo_t, si_signo)	== 0x00);
 static_assert(offsetof(siginfo_t, si_errno)	== 0x04);
 static_assert(offsetof(siginfo_t, si_code)	== 0x08);
diff --git a/arch/arm64/kernel/signal.c b/arch/arm64/kernel/signal.c
index af8bd2af1298..ad4bd27fc044 100644
--- a/arch/arm64/kernel/signal.c
+++ b/arch/arm64/kernel/signal.c
@@ -985,6 +985,8 @@ static_assert(NSIGBUS	== 5);
 static_assert(NSIGTRAP	== 6);
 static_assert(NSIGCHLD	== 6);
 static_assert(NSIGSYS	== 2);
+static_assert(sizeof(siginfo_t) == 128);
+static_assert(__alignof__(siginfo_t) == 8);
 static_assert(offsetof(siginfo_t, si_signo)	== 0x00);
 static_assert(offsetof(siginfo_t, si_errno)	== 0x04);
 static_assert(offsetof(siginfo_t, si_code)	== 0x08);
diff --git a/arch/arm64/kernel/signal32.c b/arch/arm64/kernel/signal32.c
index b6afb646515f..ee6c7484e130 100644
--- a/arch/arm64/kernel/signal32.c
+++ b/arch/arm64/kernel/signal32.c
@@ -469,6 +469,8 @@ static_assert(NSIGBUS	== 5);
 static_assert(NSIGTRAP	== 6);
 static_assert(NSIGCHLD	== 6);
 static_assert(NSIGSYS	== 2);
+static_assert(sizeof(compat_siginfo_t) == 128);
+static_assert(__alignof__(compat_siginfo_t) == 4);
 static_assert(offsetof(compat_siginfo_t, si_signo)	== 0x00);
 static_assert(offsetof(compat_siginfo_t, si_errno)	== 0x04);
 static_assert(offsetof(compat_siginfo_t, si_code)	== 0x08);
diff --git a/arch/sparc/kernel/signal32.c b/arch/sparc/kernel/signal32.c
index 778ed5c26d4a..32b977f253e3 100644
--- a/arch/sparc/kernel/signal32.c
+++ b/arch/sparc/kernel/signal32.c
@@ -757,6 +757,8 @@ static_assert(NSIGBUS	== 5);
 static_assert(NSIGTRAP	== 6);
 static_assert(NSIGCHLD	== 6);
 static_assert(NSIGSYS	== 2);
+static_assert(sizeof(compat_siginfo_t) == 128);
+static_assert(__alignof__(compat_siginfo_t) == 4);
 static_assert(offsetof(compat_siginfo_t, si_signo)	== 0x00);
 static_assert(offsetof(compat_siginfo_t, si_errno)	== 0x04);
 static_assert(offsetof(compat_siginfo_t, si_code)	== 0x08);
diff --git a/arch/sparc/kernel/signal_64.c b/arch/sparc/kernel/signal_64.c
index c9bbf5f29078..e9dda9db156c 100644
--- a/arch/sparc/kernel/signal_64.c
+++ b/arch/sparc/kernel/signal_64.c
@@ -567,6 +567,8 @@ static_assert(NSIGBUS	== 5);
 static_assert(NSIGTRAP	== 6);
 static_assert(NSIGCHLD	== 6);
 static_assert(NSIGSYS	== 2);
+static_assert(sizeof(siginfo_t) == 128);
+static_assert(__alignof__(siginfo_t) == 8);
 static_assert(offsetof(siginfo_t, si_signo)	== 0x00);
 static_assert(offsetof(siginfo_t, si_errno)	== 0x04);
 static_assert(offsetof(siginfo_t, si_code)	== 0x08);
diff --git a/arch/x86/kernel/signal_compat.c b/arch/x86/kernel/signal_compat.c
index 0e5d0a7e203b..e735bc129331 100644
--- a/arch/x86/kernel/signal_compat.c
+++ b/arch/x86/kernel/signal_compat.c
@@ -34,7 +34,13 @@ static inline void signal_compat_build_tests(void)
 	BUILD_BUG_ON(NSIGSYS  != 2);
 
 	/* This is part of the ABI and can never change in size: */
+	BUILD_BUG_ON(sizeof(siginfo_t) != 128);
 	BUILD_BUG_ON(sizeof(compat_siginfo_t) != 128);
+
+	/* This is a part of the ABI and can never change in alignment */
+	BUILD_BUG_ON(__alignof__(siginfo_t) != 8);
+	BUILD_BUG_ON(__alignof__(compat_siginfo_t) != 4);
+
 	/*
 	 * The offsets of all the (unioned) si_fields are fixed
 	 * in the ABI, of course.  Make sure none of them ever
diff --git a/include/uapi/asm-generic/siginfo.h b/include/uapi/asm-generic/siginfo.h
index 03d6f6d2c1fe..91c80d0c10c5 100644
--- a/include/uapi/asm-generic/siginfo.h
+++ b/include/uapi/asm-generic/siginfo.h
@@ -29,6 +29,11 @@ typedef union sigval {
 #define __ARCH_SI_ATTRIBUTES
 #endif
 
+/*
+ * Be careful when extending this union.  On 32bit siginfo_t is 32bit
+ * aligned.  Which means that a 64bit field or any other field that
+ * would increase the alignment of siginfo_t will break the ABI.
+ */
 union __sifields {
 	/* kill() */
 	struct {
-- 
2.30.1

Re: [PATCH v3 04/12] signal: Verify the alignment and size of siginfo_t

[Marco Elver]

On Wed, 5 May 2021 at 16:11, Eric W. Beiderman <ebiederm@xmission.com> wrote:
> From: "Eric W. Biederman" <ebiederm@xmission.com>
>
> Update the static assertions about siginfo_t to also describe
> it's alignment and size.
>
> While investigating if it was possible to add a 64bit field into
> siginfo_t[1] it became apparent that the alignment of siginfo_t
> is as much a part of the ABI as the size of the structure.
>
> If the alignment changes siginfo_t when embedded in another structure
> can move to a different offset.  Which is not acceptable from an ABI
> structure.
>
> So document that fact and add static assertions to notify developers
> if they change change the alignment by accident.
>
> [1] https://lkml.kernel.org/r/YJEZdhe6JGFNYlum@elver.google.com
> Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>

Acked-by: Marco Elver <elver@google.com>

> ---
>  arch/arm/kernel/signal.c           | 2 ++
>  arch/arm64/kernel/signal.c         | 2 ++
>  arch/arm64/kernel/signal32.c       | 2 ++
>  arch/sparc/kernel/signal32.c       | 2 ++
>  arch/sparc/kernel/signal_64.c      | 2 ++
>  arch/x86/kernel/signal_compat.c    | 6 ++++++
>  include/uapi/asm-generic/siginfo.h | 5 +++++
>  7 files changed, 21 insertions(+)
>
> diff --git a/arch/arm/kernel/signal.c b/arch/arm/kernel/signal.c
> index 2dac5d2c5cf6..643bcb0f091b 100644
> --- a/arch/arm/kernel/signal.c
> +++ b/arch/arm/kernel/signal.c
> @@ -737,6 +737,8 @@ static_assert(NSIGBUS       == 5);
>  static_assert(NSIGTRAP == 6);
>  static_assert(NSIGCHLD == 6);
>  static_assert(NSIGSYS  == 2);
> +static_assert(sizeof(siginfo_t) == 128);
> +static_assert(__alignof__(siginfo_t) == 4);
>  static_assert(offsetof(siginfo_t, si_signo)    == 0x00);
>  static_assert(offsetof(siginfo_t, si_errno)    == 0x04);
>  static_assert(offsetof(siginfo_t, si_code)     == 0x08);
> diff --git a/arch/arm64/kernel/signal.c b/arch/arm64/kernel/signal.c
> index af8bd2af1298..ad4bd27fc044 100644
> --- a/arch/arm64/kernel/signal.c
> +++ b/arch/arm64/kernel/signal.c
> @@ -985,6 +985,8 @@ static_assert(NSIGBUS       == 5);
>  static_assert(NSIGTRAP == 6);
>  static_assert(NSIGCHLD == 6);
>  static_assert(NSIGSYS  == 2);
> +static_assert(sizeof(siginfo_t) == 128);

Would using SI_MAX_SIZE be appropriate? Perhaps not.. in case somebody
changes it, given these static asserts are meant to double-check.

I leave it to you to decide what makes more sense.

> +static_assert(__alignof__(siginfo_t) == 8);
>  static_assert(offsetof(siginfo_t, si_signo)    == 0x00);
>  static_assert(offsetof(siginfo_t, si_errno)    == 0x04);
>  static_assert(offsetof(siginfo_t, si_code)     == 0x08);
> diff --git a/arch/arm64/kernel/signal32.c b/arch/arm64/kernel/signal32.c
> index b6afb646515f..ee6c7484e130 100644
> --- a/arch/arm64/kernel/signal32.c
> +++ b/arch/arm64/kernel/signal32.c
> @@ -469,6 +469,8 @@ static_assert(NSIGBUS       == 5);
>  static_assert(NSIGTRAP == 6);
>  static_assert(NSIGCHLD == 6);
>  static_assert(NSIGSYS  == 2);
> +static_assert(sizeof(compat_siginfo_t) == 128);
> +static_assert(__alignof__(compat_siginfo_t) == 4);
>  static_assert(offsetof(compat_siginfo_t, si_signo)     == 0x00);
>  static_assert(offsetof(compat_siginfo_t, si_errno)     == 0x04);
>  static_assert(offsetof(compat_siginfo_t, si_code)      == 0x08);
> diff --git a/arch/sparc/kernel/signal32.c b/arch/sparc/kernel/signal32.c
> index 778ed5c26d4a..32b977f253e3 100644
> --- a/arch/sparc/kernel/signal32.c
> +++ b/arch/sparc/kernel/signal32.c
> @@ -757,6 +757,8 @@ static_assert(NSIGBUS       == 5);
>  static_assert(NSIGTRAP == 6);
>  static_assert(NSIGCHLD == 6);
>  static_assert(NSIGSYS  == 2);
> +static_assert(sizeof(compat_siginfo_t) == 128);
> +static_assert(__alignof__(compat_siginfo_t) == 4);
>  static_assert(offsetof(compat_siginfo_t, si_signo)     == 0x00);
>  static_assert(offsetof(compat_siginfo_t, si_errno)     == 0x04);
>  static_assert(offsetof(compat_siginfo_t, si_code)      == 0x08);
> diff --git a/arch/sparc/kernel/signal_64.c b/arch/sparc/kernel/signal_64.c
> index c9bbf5f29078..e9dda9db156c 100644
> --- a/arch/sparc/kernel/signal_64.c
> +++ b/arch/sparc/kernel/signal_64.c
> @@ -567,6 +567,8 @@ static_assert(NSIGBUS       == 5);
>  static_assert(NSIGTRAP == 6);
>  static_assert(NSIGCHLD == 6);
>  static_assert(NSIGSYS  == 2);
> +static_assert(sizeof(siginfo_t) == 128);
> +static_assert(__alignof__(siginfo_t) == 8);
>  static_assert(offsetof(siginfo_t, si_signo)    == 0x00);
>  static_assert(offsetof(siginfo_t, si_errno)    == 0x04);
>  static_assert(offsetof(siginfo_t, si_code)     == 0x08);
> diff --git a/arch/x86/kernel/signal_compat.c b/arch/x86/kernel/signal_compat.c
> index 0e5d0a7e203b..e735bc129331 100644
> --- a/arch/x86/kernel/signal_compat.c
> +++ b/arch/x86/kernel/signal_compat.c
> @@ -34,7 +34,13 @@ static inline void signal_compat_build_tests(void)
>         BUILD_BUG_ON(NSIGSYS  != 2);
>
>         /* This is part of the ABI and can never change in size: */
> +       BUILD_BUG_ON(sizeof(siginfo_t) != 128);
>         BUILD_BUG_ON(sizeof(compat_siginfo_t) != 128);
> +
> +       /* This is a part of the ABI and can never change in alignment */
> +       BUILD_BUG_ON(__alignof__(siginfo_t) != 8);
> +       BUILD_BUG_ON(__alignof__(compat_siginfo_t) != 4);
> +
>         /*
>          * The offsets of all the (unioned) si_fields are fixed
>          * in the ABI, of course.  Make sure none of them ever
> diff --git a/include/uapi/asm-generic/siginfo.h b/include/uapi/asm-generic/siginfo.h
> index 03d6f6d2c1fe..91c80d0c10c5 100644
> --- a/include/uapi/asm-generic/siginfo.h
> +++ b/include/uapi/asm-generic/siginfo.h
> @@ -29,6 +29,11 @@ typedef union sigval {
>  #define __ARCH_SI_ATTRIBUTES
>  #endif
>
> +/*
> + * Be careful when extending this union.  On 32bit siginfo_t is 32bit
> + * aligned.  Which means that a 64bit field or any other field that
> + * would increase the alignment of siginfo_t will break the ABI.
> + */
>  union __sifields {
>         /* kill() */
>         struct {
> --
> 2.30.1
>

[PATCH v3 05/12] siginfo: Move si_trapno inside the union inside _si_fault

[Eric W. Beiderman]

From: "Eric W. Biederman" <ebiederm@xmission.com>

It turns out that linux uses si_trapno very sparingly, and as such it
can be considered extra information for a very narrow selection of
signals, rather than information that is present with every fault
reported in siginfo.

As such move si_trapno inside the union inside of _si_fault.  This
results in no change in placement, and makes it eaiser
to extend _si_fault in the future as this reduces the number of
special cases.  In particular with si_trapno included in the union it
is no longer a concern that the union must be pointer alligned on most
architectures because the union followes immediately after si_addr
which is a pointer.

This change results in a difference in siginfo field placement on
sparc and alpha for the fields si_addr_lsb, si_lower, si_upper,
si_pkey, and si_perf.  These architectures do not implement the
signals that would use si_addr_lsb, si_lower, si_upper, si_pkey, and
si_perf.  Further these architecture have not yet implemented the
userspace that would use si_perf.

The point of this change is in fact to correct these placement issues
before sparc or alpha grow userspace that cares.  This change was
discussed[1] and the agreement is that this change is currently safe.

[1]: https://lkml.kernel.org/r/CAK8P3a0+uKYwL1NhY6Hvtieghba2hKYGD6hcKx5n8=4Gtt+pHA@mail.gmail.com
Acked-by: Marco Elver <elver@google.com>
v1: https://lkml.kernel.org/r/m1tunns7yf.fsf_-_@fess.ebiederm.org
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
---
 arch/sparc/kernel/signal32.c       | 10 +++++-----
 arch/sparc/kernel/signal_64.c      | 10 +++++-----
 arch/x86/kernel/signal_compat.c    |  3 +++
 include/linux/compat.h             |  5 ++---
 include/uapi/asm-generic/siginfo.h |  7 ++-----
 kernel/signal.c                    |  1 +
 6 files changed, 18 insertions(+), 18 deletions(-)

diff --git a/arch/sparc/kernel/signal32.c b/arch/sparc/kernel/signal32.c
index 32b977f253e3..5573722e34ad 100644
--- a/arch/sparc/kernel/signal32.c
+++ b/arch/sparc/kernel/signal32.c
@@ -774,10 +774,10 @@ static_assert(offsetof(compat_siginfo_t, si_int)	== 0x14);
 static_assert(offsetof(compat_siginfo_t, si_ptr)	== 0x14);
 static_assert(offsetof(compat_siginfo_t, si_addr)	== 0x0c);
 static_assert(offsetof(compat_siginfo_t, si_trapno)	== 0x10);
-static_assert(offsetof(compat_siginfo_t, si_addr_lsb)	== 0x14);
-static_assert(offsetof(compat_siginfo_t, si_lower)	== 0x18);
-static_assert(offsetof(compat_siginfo_t, si_upper)	== 0x1c);
-static_assert(offsetof(compat_siginfo_t, si_pkey)	== 0x18);
-static_assert(offsetof(compat_siginfo_t, si_perf)	== 0x14);
+static_assert(offsetof(compat_siginfo_t, si_addr_lsb)	== 0x10);
+static_assert(offsetof(compat_siginfo_t, si_lower)	== 0x14);
+static_assert(offsetof(compat_siginfo_t, si_upper)	== 0x18);
+static_assert(offsetof(compat_siginfo_t, si_pkey)	== 0x14);
+static_assert(offsetof(compat_siginfo_t, si_perf)	== 0x10);
 static_assert(offsetof(compat_siginfo_t, si_band)	== 0x0c);
 static_assert(offsetof(compat_siginfo_t, si_fd)		== 0x10);
diff --git a/arch/sparc/kernel/signal_64.c b/arch/sparc/kernel/signal_64.c
index e9dda9db156c..a69a78984c36 100644
--- a/arch/sparc/kernel/signal_64.c
+++ b/arch/sparc/kernel/signal_64.c
@@ -584,10 +584,10 @@ static_assert(offsetof(siginfo_t, si_int)	== 0x18);
 static_assert(offsetof(siginfo_t, si_ptr)	== 0x18);
 static_assert(offsetof(siginfo_t, si_addr)	== 0x10);
 static_assert(offsetof(siginfo_t, si_trapno)	== 0x18);
-static_assert(offsetof(siginfo_t, si_addr_lsb)	== 0x20);
-static_assert(offsetof(siginfo_t, si_lower)	== 0x28);
-static_assert(offsetof(siginfo_t, si_upper)	== 0x30);
-static_assert(offsetof(siginfo_t, si_pkey)	== 0x28);
-static_assert(offsetof(siginfo_t, si_perf)	== 0x20);
+static_assert(offsetof(siginfo_t, si_addr_lsb)	== 0x18);
+static_assert(offsetof(siginfo_t, si_lower)	== 0x20);
+static_assert(offsetof(siginfo_t, si_upper)	== 0x28);
+static_assert(offsetof(siginfo_t, si_pkey)	== 0x20);
+static_assert(offsetof(siginfo_t, si_perf)	== 0x18);
 static_assert(offsetof(siginfo_t, si_band)	== 0x10);
 static_assert(offsetof(siginfo_t, si_fd)	== 0x14);
diff --git a/arch/x86/kernel/signal_compat.c b/arch/x86/kernel/signal_compat.c
index e735bc129331..c9601f092a1e 100644
--- a/arch/x86/kernel/signal_compat.c
+++ b/arch/x86/kernel/signal_compat.c
@@ -133,6 +133,9 @@ static inline void signal_compat_build_tests(void)
 	BUILD_BUG_ON(offsetof(siginfo_t, si_addr) != 0x10);
 	BUILD_BUG_ON(offsetof(compat_siginfo_t, si_addr) != 0x0C);
 
+	BUILD_BUG_ON(offsetof(siginfo_t, si_trapno) != 0x18);
+	BUILD_BUG_ON(offsetof(compat_siginfo_t, si_trapno) != 0x10);
+
 	BUILD_BUG_ON(offsetof(siginfo_t, si_addr_lsb) != 0x18);
 	BUILD_BUG_ON(offsetof(compat_siginfo_t, si_addr_lsb) != 0x10);
 
diff --git a/include/linux/compat.h b/include/linux/compat.h
index f0d2dd35d408..6af7bef15e94 100644
--- a/include/linux/compat.h
+++ b/include/linux/compat.h
@@ -214,12 +214,11 @@ typedef struct compat_siginfo {
 		/* SIGILL, SIGFPE, SIGSEGV, SIGBUS, SIGTRAP, SIGEMT */
 		struct {
 			compat_uptr_t _addr;	/* faulting insn/memory ref. */
-#ifdef __ARCH_SI_TRAPNO
-			int _trapno;	/* TRAP # which caused the signal */
-#endif
 #define __COMPAT_ADDR_BND_PKEY_PAD  (__alignof__(compat_uptr_t) < sizeof(short) ? \
 				     sizeof(short) : __alignof__(compat_uptr_t))
 			union {
+				/* used on alpha and sparc */
+				int _trapno;	/* TRAP # which caused the signal */
 				/*
 				 * used when si_code=BUS_MCEERR_AR or
 				 * used when si_code=BUS_MCEERR_AO
diff --git a/include/uapi/asm-generic/siginfo.h b/include/uapi/asm-generic/siginfo.h
index 91c80d0c10c5..3503282021aa 100644
--- a/include/uapi/asm-generic/siginfo.h
+++ b/include/uapi/asm-generic/siginfo.h
@@ -68,9 +68,6 @@ union __sifields {
 	/* SIGILL, SIGFPE, SIGSEGV, SIGBUS, SIGTRAP, SIGEMT */
 	struct {
 		void __user *_addr; /* faulting insn/memory ref. */
-#ifdef __ARCH_SI_TRAPNO
-		int _trapno;	/* TRAP # which caused the signal */
-#endif
 #ifdef __ia64__
 		int _imm;		/* immediate value for "break" */
 		unsigned int _flags;	/* see ia64 si_flags */
@@ -80,6 +77,8 @@ union __sifields {
 #define __ADDR_BND_PKEY_PAD  (__alignof__(void *) < sizeof(short) ? \
 			      sizeof(short) : __alignof__(void *))
 		union {
+			/* used on alpha and sparc */
+			int _trapno;	/* TRAP # which caused the signal */
 			/*
 			 * used when si_code=BUS_MCEERR_AR or
 			 * used when si_code=BUS_MCEERR_AO
@@ -155,9 +154,7 @@ typedef struct siginfo {
 #define si_int		_sifields._rt._sigval.sival_int
 #define si_ptr		_sifields._rt._sigval.sival_ptr
 #define si_addr		_sifields._sigfault._addr
-#ifdef __ARCH_SI_TRAPNO
 #define si_trapno	_sifields._sigfault._trapno
-#endif
 #define si_addr_lsb	_sifields._sigfault._addr_lsb
 #define si_lower	_sifields._sigfault._addr_bnd._lower
 #define si_upper	_sifields._sigfault._addr_bnd._upper
diff --git a/kernel/signal.c b/kernel/signal.c
index c3017aa8024a..65888aec65a0 100644
--- a/kernel/signal.c
+++ b/kernel/signal.c
@@ -4607,6 +4607,7 @@ static inline void siginfo_buildtime_checks(void)
 
 	/* sigfault */
 	CHECK_OFFSET(si_addr);
+	CHECK_OFFSET(si_trapno);
 	CHECK_OFFSET(si_addr_lsb);
 	CHECK_OFFSET(si_lower);
 	CHECK_OFFSET(si_upper);
-- 
2.30.1

[PATCH v3 06/12] signal: Implement SIL_FAULT_TRAPNO

[Eric W. Beiderman]

From: "Eric W. Biederman" <ebiederm@xmission.com>

Now that si_trapno is part of the union in _si_fault and available on
all architectures, add SIL_FAULT_TRAPNO and update siginfo_layout to
return SIL_FAULT_TRAPNO when si_trapno is actually used.

Update the code that uses siginfo_layout to deal with SIL_FAULT_TRAPNO
and have the same code ignore si_trapno in in all other cases.

v1: https://lkml.kernel.org/r/m1o8dvs7s7.fsf_-_@fess.ebiederm.org
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
---
 fs/signalfd.c          |  8 +++-----
 include/linux/signal.h |  1 +
 kernel/signal.c        | 37 +++++++++++++++----------------------
 3 files changed, 19 insertions(+), 27 deletions(-)

diff --git a/fs/signalfd.c b/fs/signalfd.c
index 040a1142915f..e87e59581653 100644
--- a/fs/signalfd.c
+++ b/fs/signalfd.c
@@ -123,15 +123,13 @@ static int signalfd_copyinfo(struct signalfd_siginfo __user *uinfo,
 		 */
 	case SIL_FAULT:
 		new.ssi_addr = (long) kinfo->si_addr;
-#ifdef __ARCH_SI_TRAPNO
+		break;
+	case SIL_FAULT_TRAPNO:
+		new.ssi_addr = (long) kinfo->si_addr;
 		new.ssi_trapno = kinfo->si_trapno;
-#endif
 		break;
 	case SIL_FAULT_MCEERR:
 		new.ssi_addr = (long) kinfo->si_addr;
-#ifdef __ARCH_SI_TRAPNO
-		new.ssi_trapno = kinfo->si_trapno;
-#endif
 		new.ssi_addr_lsb = (short) kinfo->si_addr_lsb;
 		break;
 	case SIL_PERF_EVENT:
diff --git a/include/linux/signal.h b/include/linux/signal.h
index 1e98548d7cf6..5160fd45e5ca 100644
--- a/include/linux/signal.h
+++ b/include/linux/signal.h
@@ -40,6 +40,7 @@ enum siginfo_layout {
 	SIL_TIMER,
 	SIL_POLL,
 	SIL_FAULT,
+	SIL_FAULT_TRAPNO,
 	SIL_FAULT_MCEERR,
 	SIL_FAULT_BNDERR,
 	SIL_FAULT_PKUERR,
diff --git a/kernel/signal.c b/kernel/signal.c
index 65888aec65a0..3d3ba7949788 100644
--- a/kernel/signal.c
+++ b/kernel/signal.c
@@ -1194,6 +1194,7 @@ static inline bool has_si_pid_and_uid(struct kernel_siginfo *info)
 	case SIL_TIMER:
 	case SIL_POLL:
 	case SIL_FAULT:
+	case SIL_FAULT_TRAPNO:
 	case SIL_FAULT_MCEERR:
 	case SIL_FAULT_BNDERR:
 	case SIL_FAULT_PKUERR:
@@ -2527,6 +2528,7 @@ static void hide_si_addr_tag_bits(struct ksignal *ksig)
 {
 	switch (siginfo_layout(ksig->sig, ksig->info.si_code)) {
 	case SIL_FAULT:
+	case SIL_FAULT_TRAPNO:
 	case SIL_FAULT_MCEERR:
 	case SIL_FAULT_BNDERR:
 	case SIL_FAULT_PKUERR:
@@ -3206,6 +3208,13 @@ enum siginfo_layout siginfo_layout(unsigned sig, int si_code)
 			if ((sig == SIGBUS) &&
 			    (si_code >= BUS_MCEERR_AR) && (si_code <= BUS_MCEERR_AO))
 				layout = SIL_FAULT_MCEERR;
+			else if (IS_ENABLED(CONFIG_ALPHA) &&
+				 ((sig == SIGFPE) ||
+				  ((sig == SIGTRAP) && (si_code == TRAP_UNK))))
+				layout = SIL_FAULT_TRAPNO;
+			else if (IS_ENABLED(CONFIG_SPARC) &&
+				 (sig == SIGILL) && (si_code == ILL_ILLTRP))
+				layout = SIL_FAULT_TRAPNO;
 			else if ((sig == SIGSEGV) && (si_code == SEGV_BNDERR))
 				layout = SIL_FAULT_BNDERR;
 #ifdef SEGV_PKUERR
@@ -3317,30 +3326,22 @@ void copy_siginfo_to_external32(struct compat_siginfo *to,
 		break;
 	case SIL_FAULT:
 		to->si_addr = ptr_to_compat(from->si_addr);
-#ifdef __ARCH_SI_TRAPNO
+		break;
+	case SIL_FAULT_TRAPNO:
+		to->si_addr = ptr_to_compat(from->si_addr);
 		to->si_trapno = from->si_trapno;
-#endif
 		break;
 	case SIL_FAULT_MCEERR:
 		to->si_addr = ptr_to_compat(from->si_addr);
-#ifdef __ARCH_SI_TRAPNO
-		to->si_trapno = from->si_trapno;
-#endif
 		to->si_addr_lsb = from->si_addr_lsb;
 		break;
 	case SIL_FAULT_BNDERR:
 		to->si_addr = ptr_to_compat(from->si_addr);
-#ifdef __ARCH_SI_TRAPNO
-		to->si_trapno = from->si_trapno;
-#endif
 		to->si_lower = ptr_to_compat(from->si_lower);
 		to->si_upper = ptr_to_compat(from->si_upper);
 		break;
 	case SIL_FAULT_PKUERR:
 		to->si_addr = ptr_to_compat(from->si_addr);
-#ifdef __ARCH_SI_TRAPNO
-		to->si_trapno = from->si_trapno;
-#endif
 		to->si_pkey = from->si_pkey;
 		break;
 	case SIL_PERF_EVENT:
@@ -3401,30 +3402,22 @@ static int post_copy_siginfo_from_user32(kernel_siginfo_t *to,
 		break;
 	case SIL_FAULT:
 		to->si_addr = compat_ptr(from->si_addr);
-#ifdef __ARCH_SI_TRAPNO
+		break;
+	case SIL_FAULT_TRAPNO:
+		to->si_addr = compat_ptr(from->si_addr);
 		to->si_trapno = from->si_trapno;
-#endif
 		break;
 	case SIL_FAULT_MCEERR:
 		to->si_addr = compat_ptr(from->si_addr);
-#ifdef __ARCH_SI_TRAPNO
-		to->si_trapno = from->si_trapno;
-#endif
 		to->si_addr_lsb = from->si_addr_lsb;
 		break;
 	case SIL_FAULT_BNDERR:
 		to->si_addr = compat_ptr(from->si_addr);
-#ifdef __ARCH_SI_TRAPNO
-		to->si_trapno = from->si_trapno;
-#endif
 		to->si_lower = compat_ptr(from->si_lower);
 		to->si_upper = compat_ptr(from->si_upper);
 		break;
 	case SIL_FAULT_PKUERR:
 		to->si_addr = compat_ptr(from->si_addr);
-#ifdef __ARCH_SI_TRAPNO
-		to->si_trapno = from->si_trapno;
-#endif
 		to->si_pkey = from->si_pkey;
 		break;
 	case SIL_PERF_EVENT:
-- 
2.30.1

Re: [PATCH v3 06/12] signal: Implement SIL_FAULT_TRAPNO

[Marco Elver]

On Wed, 5 May 2021 at 16:11, Eric W. Beiderman <ebiederm@xmission.com> wrote:
> From: "Eric W. Biederman" <ebiederm@xmission.com>
>
> Now that si_trapno is part of the union in _si_fault and available on
> all architectures, add SIL_FAULT_TRAPNO and update siginfo_layout to
> return SIL_FAULT_TRAPNO when si_trapno is actually used.
>
> Update the code that uses siginfo_layout to deal with SIL_FAULT_TRAPNO
> and have the same code ignore si_trapno in in all other cases.
>
> v1: https://lkml.kernel.org/r/m1o8dvs7s7.fsf_-_@fess.ebiederm.org
> Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>

Reviewed-by: Marco Elver <elver@google.com>


> ---
>  fs/signalfd.c          |  8 +++-----
>  include/linux/signal.h |  1 +
>  kernel/signal.c        | 37 +++++++++++++++----------------------
>  3 files changed, 19 insertions(+), 27 deletions(-)
>
> diff --git a/fs/signalfd.c b/fs/signalfd.c
> index 040a1142915f..e87e59581653 100644
> --- a/fs/signalfd.c
> +++ b/fs/signalfd.c
> @@ -123,15 +123,13 @@ static int signalfd_copyinfo(struct signalfd_siginfo __user *uinfo,
>                  */
>         case SIL_FAULT:
>                 new.ssi_addr = (long) kinfo->si_addr;
> -#ifdef __ARCH_SI_TRAPNO
> +               break;
> +       case SIL_FAULT_TRAPNO:
> +               new.ssi_addr = (long) kinfo->si_addr;
>                 new.ssi_trapno = kinfo->si_trapno;
> -#endif
>                 break;
>         case SIL_FAULT_MCEERR:
>                 new.ssi_addr = (long) kinfo->si_addr;
> -#ifdef __ARCH_SI_TRAPNO
> -               new.ssi_trapno = kinfo->si_trapno;
> -#endif
>                 new.ssi_addr_lsb = (short) kinfo->si_addr_lsb;
>                 break;
>         case SIL_PERF_EVENT:
> diff --git a/include/linux/signal.h b/include/linux/signal.h
> index 1e98548d7cf6..5160fd45e5ca 100644
> --- a/include/linux/signal.h
> +++ b/include/linux/signal.h
> @@ -40,6 +40,7 @@ enum siginfo_layout {
>         SIL_TIMER,
>         SIL_POLL,
>         SIL_FAULT,
> +       SIL_FAULT_TRAPNO,
>         SIL_FAULT_MCEERR,
>         SIL_FAULT_BNDERR,
>         SIL_FAULT_PKUERR,
> diff --git a/kernel/signal.c b/kernel/signal.c
> index 65888aec65a0..3d3ba7949788 100644
> --- a/kernel/signal.c
> +++ b/kernel/signal.c
> @@ -1194,6 +1194,7 @@ static inline bool has_si_pid_and_uid(struct kernel_siginfo *info)
>         case SIL_TIMER:
>         case SIL_POLL:
>         case SIL_FAULT:
> +       case SIL_FAULT_TRAPNO:
>         case SIL_FAULT_MCEERR:
>         case SIL_FAULT_BNDERR:
>         case SIL_FAULT_PKUERR:
> @@ -2527,6 +2528,7 @@ static void hide_si_addr_tag_bits(struct ksignal *ksig)
>  {
>         switch (siginfo_layout(ksig->sig, ksig->info.si_code)) {
>         case SIL_FAULT:
> +       case SIL_FAULT_TRAPNO:
>         case SIL_FAULT_MCEERR:
>         case SIL_FAULT_BNDERR:
>         case SIL_FAULT_PKUERR:
> @@ -3206,6 +3208,13 @@ enum siginfo_layout siginfo_layout(unsigned sig, int si_code)
>                         if ((sig == SIGBUS) &&
>                             (si_code >= BUS_MCEERR_AR) && (si_code <= BUS_MCEERR_AO))
>                                 layout = SIL_FAULT_MCEERR;
> +                       else if (IS_ENABLED(CONFIG_ALPHA) &&
> +                                ((sig == SIGFPE) ||
> +                                 ((sig == SIGTRAP) && (si_code == TRAP_UNK))))
> +                               layout = SIL_FAULT_TRAPNO;
> +                       else if (IS_ENABLED(CONFIG_SPARC) &&
> +                                (sig == SIGILL) && (si_code == ILL_ILLTRP))
> +                               layout = SIL_FAULT_TRAPNO;
>                         else if ((sig == SIGSEGV) && (si_code == SEGV_BNDERR))
>                                 layout = SIL_FAULT_BNDERR;
>  #ifdef SEGV_PKUERR
> @@ -3317,30 +3326,22 @@ void copy_siginfo_to_external32(struct compat_siginfo *to,
>                 break;
>         case SIL_FAULT:
>                 to->si_addr = ptr_to_compat(from->si_addr);
> -#ifdef __ARCH_SI_TRAPNO
> +               break;
> +       case SIL_FAULT_TRAPNO:
> +               to->si_addr = ptr_to_compat(from->si_addr);
>                 to->si_trapno = from->si_trapno;
> -#endif
>                 break;
>         case SIL_FAULT_MCEERR:
>                 to->si_addr = ptr_to_compat(from->si_addr);
> -#ifdef __ARCH_SI_TRAPNO
> -               to->si_trapno = from->si_trapno;
> -#endif
>                 to->si_addr_lsb = from->si_addr_lsb;
>                 break;
>         case SIL_FAULT_BNDERR:
>                 to->si_addr = ptr_to_compat(from->si_addr);
> -#ifdef __ARCH_SI_TRAPNO
> -               to->si_trapno = from->si_trapno;
> -#endif
>                 to->si_lower = ptr_to_compat(from->si_lower);
>                 to->si_upper = ptr_to_compat(from->si_upper);
>                 break;
>         case SIL_FAULT_PKUERR:
>                 to->si_addr = ptr_to_compat(from->si_addr);
> -#ifdef __ARCH_SI_TRAPNO
> -               to->si_trapno = from->si_trapno;
> -#endif
>                 to->si_pkey = from->si_pkey;
>                 break;
>         case SIL_PERF_EVENT:
> @@ -3401,30 +3402,22 @@ static int post_copy_siginfo_from_user32(kernel_siginfo_t *to,
>                 break;
>         case SIL_FAULT:
>                 to->si_addr = compat_ptr(from->si_addr);
> -#ifdef __ARCH_SI_TRAPNO
> +               break;
> +       case SIL_FAULT_TRAPNO:
> +               to->si_addr = compat_ptr(from->si_addr);
>                 to->si_trapno = from->si_trapno;
> -#endif
>                 break;
>         case SIL_FAULT_MCEERR:
>                 to->si_addr = compat_ptr(from->si_addr);
> -#ifdef __ARCH_SI_TRAPNO
> -               to->si_trapno = from->si_trapno;
> -#endif
>                 to->si_addr_lsb = from->si_addr_lsb;
>                 break;
>         case SIL_FAULT_BNDERR:
>                 to->si_addr = compat_ptr(from->si_addr);
> -#ifdef __ARCH_SI_TRAPNO
> -               to->si_trapno = from->si_trapno;
> -#endif
>                 to->si_lower = compat_ptr(from->si_lower);
>                 to->si_upper = compat_ptr(from->si_upper);
>                 break;
>         case SIL_FAULT_PKUERR:
>                 to->si_addr = compat_ptr(from->si_addr);
> -#ifdef __ARCH_SI_TRAPNO
> -               to->si_trapno = from->si_trapno;
> -#endif
>                 to->si_pkey = from->si_pkey;
>                 break;
>         case SIL_PERF_EVENT:
> --
> 2.30.1

[PATCH v3 07/12] signal: Use dedicated helpers to send signals with si_trapno set

[Eric W. Beiderman]

From: "Eric W. Biederman" <ebiederm@xmission.com>

Now that si_trapno is no longer expected to be present for every fault
reported using siginfo on alpha and sparc remove the trapno parameter
from force_sig_fault, force_sig_fault_to_task and send_sig_fault.

Add two new helpers force_sig_fault_trapno and send_sig_fautl_trapno
for those signals where trapno is expected to be set.

v1: https://lkml.kernel.org/r/m1eeers7q7.fsf_-_@fess.ebiederm.org
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
---
 arch/alpha/kernel/osf_sys.c      |  2 +-
 arch/alpha/kernel/signal.c       |  4 +--
 arch/alpha/kernel/traps.c        | 24 ++++++++---------
 arch/alpha/mm/fault.c            |  4 +--
 arch/sparc/kernel/process_64.c   |  2 +-
 arch/sparc/kernel/sys_sparc_32.c |  2 +-
 arch/sparc/kernel/sys_sparc_64.c |  2 +-
 arch/sparc/kernel/traps_32.c     | 22 ++++++++--------
 arch/sparc/kernel/traps_64.c     | 44 ++++++++++++++------------------
 arch/sparc/kernel/unaligned_32.c |  2 +-
 arch/sparc/mm/fault_32.c         |  2 +-
 arch/sparc/mm/fault_64.c         |  2 +-
 include/linux/sched/signal.h     | 12 +++------
 kernel/signal.c                  | 41 +++++++++++++++++++++--------
 14 files changed, 88 insertions(+), 77 deletions(-)

diff --git a/arch/alpha/kernel/osf_sys.c b/arch/alpha/kernel/osf_sys.c
index d5367a1c6300..80c5d7fbe66a 100644
--- a/arch/alpha/kernel/osf_sys.c
+++ b/arch/alpha/kernel/osf_sys.c
@@ -878,7 +878,7 @@ SYSCALL_DEFINE5(osf_setsysinfo, unsigned long, op, void __user *, buffer,
 
 			send_sig_fault(SIGFPE, si_code,
 				       (void __user *)NULL,  /* FIXME */
-				       0, current);
+				       current);
  		}
 		return 0;
 	}
diff --git a/arch/alpha/kernel/signal.c b/arch/alpha/kernel/signal.c
index 948b89789da8..bc077babafab 100644
--- a/arch/alpha/kernel/signal.c
+++ b/arch/alpha/kernel/signal.c
@@ -219,7 +219,7 @@ do_sigreturn(struct sigcontext __user *sc)
 
 	/* Send SIGTRAP if we're single-stepping: */
 	if (ptrace_cancel_bpt (current)) {
-		send_sig_fault(SIGTRAP, TRAP_BRKPT, (void __user *) regs->pc, 0,
+		send_sig_fault(SIGTRAP, TRAP_BRKPT, (void __user *) regs->pc,
 			       current);
 	}
 	return;
@@ -247,7 +247,7 @@ do_rt_sigreturn(struct rt_sigframe __user *frame)
 
 	/* Send SIGTRAP if we're single-stepping: */
 	if (ptrace_cancel_bpt (current)) {
-		send_sig_fault(SIGTRAP, TRAP_BRKPT, (void __user *) regs->pc, 0,
+		send_sig_fault(SIGTRAP, TRAP_BRKPT, (void __user *) regs->pc,
 			       current);
 	}
 	return;
diff --git a/arch/alpha/kernel/traps.c b/arch/alpha/kernel/traps.c
index 921d4b6e4d95..0dddf9ecc1f4 100644
--- a/arch/alpha/kernel/traps.c
+++ b/arch/alpha/kernel/traps.c
@@ -227,7 +227,7 @@ do_entArith(unsigned long summary, unsigned long write_mask,
 	}
 	die_if_kernel("Arithmetic fault", regs, 0, NULL);
 
-	send_sig_fault(SIGFPE, si_code, (void __user *) regs->pc, 0, current);
+	send_sig_fault_trapno(SIGFPE, si_code, (void __user *) regs->pc, 0, current);
 }
 
 asmlinkage void
@@ -268,12 +268,12 @@ do_entIF(unsigned long type, struct pt_regs *regs)
 			regs->pc -= 4;	/* make pc point to former bpt */
 		}
 
-		send_sig_fault(SIGTRAP, TRAP_BRKPT, (void __user *)regs->pc, 0,
+		send_sig_fault(SIGTRAP, TRAP_BRKPT, (void __user *)regs->pc,
 			       current);
 		return;
 
 	      case 1: /* bugcheck */
-		send_sig_fault(SIGTRAP, TRAP_UNK, (void __user *) regs->pc, 0,
+		send_sig_fault(SIGTRAP, TRAP_UNK, (void __user *) regs->pc,
 			       current);
 		return;
 		
@@ -335,8 +335,8 @@ do_entIF(unsigned long type, struct pt_regs *regs)
 			break;
 		}
 
-		send_sig_fault(signo, code, (void __user *) regs->pc, regs->r16,
-			       current);
+		send_sig_fault_trapno(signo, code, (void __user *) regs->pc,
+				      regs->r16, current);
 		return;
 
 	      case 4: /* opDEC */
@@ -360,9 +360,9 @@ do_entIF(unsigned long type, struct pt_regs *regs)
 			if (si_code == 0)
 				return;
 			if (si_code > 0) {
-				send_sig_fault(SIGFPE, si_code,
-					       (void __user *) regs->pc, 0,
-					       current);
+				send_sig_fault_trapno(SIGFPE, si_code,
+						      (void __user *) regs->pc,
+						      0, current);
 				return;
 			}
 		}
@@ -387,7 +387,7 @@ do_entIF(unsigned long type, struct pt_regs *regs)
 		      ;
 	}
 
-	send_sig_fault(SIGILL, ILL_ILLOPC, (void __user *)regs->pc, 0, current);
+	send_sig_fault(SIGILL, ILL_ILLOPC, (void __user *)regs->pc, current);
 }
 
 /* There is an ifdef in the PALcode in MILO that enables a 
@@ -402,7 +402,7 @@ do_entDbg(struct pt_regs *regs)
 {
 	die_if_kernel("Instruction fault", regs, 0, NULL);
 
-	force_sig_fault(SIGILL, ILL_ILLOPC, (void __user *)regs->pc, 0);
+	force_sig_fault(SIGILL, ILL_ILLOPC, (void __user *)regs->pc);
 }
 
 
@@ -964,12 +964,12 @@ do_entUnaUser(void __user * va, unsigned long opcode,
 			si_code = SEGV_MAPERR;
 		mmap_read_unlock(mm);
 	}
-	send_sig_fault(SIGSEGV, si_code, va, 0, current);
+	send_sig_fault(SIGSEGV, si_code, va, current);
 	return;
 
 give_sigbus:
 	regs->pc -= 4;
-	send_sig_fault(SIGBUS, BUS_ADRALN, va, 0, current);
+	send_sig_fault(SIGBUS, BUS_ADRALN, va, current);
 	return;
 }
 
diff --git a/arch/alpha/mm/fault.c b/arch/alpha/mm/fault.c
index 09172f017efc..eee5102c3d88 100644
--- a/arch/alpha/mm/fault.c
+++ b/arch/alpha/mm/fault.c
@@ -219,13 +219,13 @@ do_page_fault(unsigned long address, unsigned long mmcsr,
 	mmap_read_unlock(mm);
 	/* Send a sigbus, regardless of whether we were in kernel
 	   or user mode.  */
-	force_sig_fault(SIGBUS, BUS_ADRERR, (void __user *) address, 0);
+	force_sig_fault(SIGBUS, BUS_ADRERR, (void __user *) address);
 	if (!user_mode(regs))
 		goto no_context;
 	return;
 
  do_sigsegv:
-	force_sig_fault(SIGSEGV, si_code, (void __user *) address, 0);
+	force_sig_fault(SIGSEGV, si_code, (void __user *) address);
 	return;
 
 #ifdef CONFIG_ALPHA_LARGE_VMALLOC
diff --git a/arch/sparc/kernel/process_64.c b/arch/sparc/kernel/process_64.c
index 7afd0a859a78..29e67854d5a4 100644
--- a/arch/sparc/kernel/process_64.c
+++ b/arch/sparc/kernel/process_64.c
@@ -518,7 +518,7 @@ void synchronize_user_stack(void)
 
 static void stack_unaligned(unsigned long sp)
 {
-	force_sig_fault(SIGBUS, BUS_ADRALN, (void __user *) sp, 0);
+	force_sig_fault(SIGBUS, BUS_ADRALN, (void __user *) sp);
 }
 
 static const char uwfault32[] = KERN_INFO \
diff --git a/arch/sparc/kernel/sys_sparc_32.c b/arch/sparc/kernel/sys_sparc_32.c
index be77538bc038..082a551897ed 100644
--- a/arch/sparc/kernel/sys_sparc_32.c
+++ b/arch/sparc/kernel/sys_sparc_32.c
@@ -151,7 +151,7 @@ sparc_breakpoint (struct pt_regs *regs)
 #ifdef DEBUG_SPARC_BREAKPOINT
         printk ("TRAP: Entering kernel PC=%x, nPC=%x\n", regs->pc, regs->npc);
 #endif
-	force_sig_fault(SIGTRAP, TRAP_BRKPT, (void __user *)regs->pc, 0);
+	force_sig_fault(SIGTRAP, TRAP_BRKPT, (void __user *)regs->pc);
 
 #ifdef DEBUG_SPARC_BREAKPOINT
 	printk ("TRAP: Returning to space: PC=%x nPC=%x\n", regs->pc, regs->npc);
diff --git a/arch/sparc/kernel/sys_sparc_64.c b/arch/sparc/kernel/sys_sparc_64.c
index 6b92fadb6ec7..1e9a9e016237 100644
--- a/arch/sparc/kernel/sys_sparc_64.c
+++ b/arch/sparc/kernel/sys_sparc_64.c
@@ -514,7 +514,7 @@ asmlinkage void sparc_breakpoint(struct pt_regs *regs)
 #ifdef DEBUG_SPARC_BREAKPOINT
         printk ("TRAP: Entering kernel PC=%lx, nPC=%lx\n", regs->tpc, regs->tnpc);
 #endif
-	force_sig_fault(SIGTRAP, TRAP_BRKPT, (void __user *)regs->tpc, 0);
+	force_sig_fault(SIGTRAP, TRAP_BRKPT, (void __user *)regs->tpc);
 #ifdef DEBUG_SPARC_BREAKPOINT
 	printk ("TRAP: Returning to space: PC=%lx nPC=%lx\n", regs->tpc, regs->tnpc);
 #endif
diff --git a/arch/sparc/kernel/traps_32.c b/arch/sparc/kernel/traps_32.c
index 247a0d9683b2..5630e5a395e0 100644
--- a/arch/sparc/kernel/traps_32.c
+++ b/arch/sparc/kernel/traps_32.c
@@ -102,8 +102,8 @@ void do_hw_interrupt(struct pt_regs *regs, unsigned long type)
 	if(regs->psr & PSR_PS)
 		die_if_kernel("Kernel bad trap", regs);
 
-	force_sig_fault(SIGILL, ILL_ILLTRP,
-			(void __user *)regs->pc, type - 0x80);
+	force_sig_fault_trapno(SIGILL, ILL_ILLTRP,
+			       (void __user *)regs->pc, type - 0x80);
 }
 
 void do_illegal_instruction(struct pt_regs *regs, unsigned long pc, unsigned long npc,
@@ -116,7 +116,7 @@ void do_illegal_instruction(struct pt_regs *regs, unsigned long pc, unsigned lon
 	       regs->pc, *(unsigned long *)regs->pc);
 #endif
 
-	send_sig_fault(SIGILL, ILL_ILLOPC, (void __user *)pc, 0, current);
+	send_sig_fault(SIGILL, ILL_ILLOPC, (void __user *)pc, current);
 }
 
 void do_priv_instruction(struct pt_regs *regs, unsigned long pc, unsigned long npc,
@@ -124,7 +124,7 @@ void do_priv_instruction(struct pt_regs *regs, unsigned long pc, unsigned long n
 {
 	if(psr & PSR_PS)
 		die_if_kernel("Penguin instruction from Penguin mode??!?!", regs);
-	send_sig_fault(SIGILL, ILL_PRVOPC, (void __user *)pc, 0, current);
+	send_sig_fault(SIGILL, ILL_PRVOPC, (void __user *)pc, current);
 }
 
 /* XXX User may want to be allowed to do this. XXX */
@@ -145,7 +145,7 @@ void do_memaccess_unaligned(struct pt_regs *regs, unsigned long pc, unsigned lon
 #endif
 	send_sig_fault(SIGBUS, BUS_ADRALN,
 		       /* FIXME: Should dig out mna address */ (void *)0,
-		       0, current);
+		       current);
 }
 
 static unsigned long init_fsr = 0x0UL;
@@ -291,7 +291,7 @@ void do_fpe_trap(struct pt_regs *regs, unsigned long pc, unsigned long npc,
 		else if (fsr & 0x01)
 			code = FPE_FLTRES;
 	}
-	send_sig_fault(SIGFPE, code, (void __user *)pc, 0, fpt);
+	send_sig_fault(SIGFPE, code, (void __user *)pc, fpt);
 #ifndef CONFIG_SMP
 	last_task_used_math = NULL;
 #endif
@@ -305,7 +305,7 @@ void handle_tag_overflow(struct pt_regs *regs, unsigned long pc, unsigned long n
 {
 	if(psr & PSR_PS)
 		die_if_kernel("Penguin overflow trap from kernel mode", regs);
-	send_sig_fault(SIGEMT, EMT_TAGOVF, (void __user *)pc, 0, current);
+	send_sig_fault(SIGEMT, EMT_TAGOVF, (void __user *)pc, current);
 }
 
 void handle_watchpoint(struct pt_regs *regs, unsigned long pc, unsigned long npc,
@@ -327,13 +327,13 @@ void handle_reg_access(struct pt_regs *regs, unsigned long pc, unsigned long npc
 	printk("Register Access Exception at PC %08lx NPC %08lx PSR %08lx\n",
 	       pc, npc, psr);
 #endif
-	force_sig_fault(SIGBUS, BUS_OBJERR, (void __user *)pc, 0);
+	force_sig_fault(SIGBUS, BUS_OBJERR, (void __user *)pc);
 }
 
 void handle_cp_disabled(struct pt_regs *regs, unsigned long pc, unsigned long npc,
 			unsigned long psr)
 {
-	send_sig_fault(SIGILL, ILL_COPROC, (void __user *)pc, 0, current);
+	send_sig_fault(SIGILL, ILL_COPROC, (void __user *)pc, current);
 }
 
 void handle_cp_exception(struct pt_regs *regs, unsigned long pc, unsigned long npc,
@@ -343,13 +343,13 @@ void handle_cp_exception(struct pt_regs *regs, unsigned long pc, unsigned long n
 	printk("Co-Processor Exception at PC %08lx NPC %08lx PSR %08lx\n",
 	       pc, npc, psr);
 #endif
-	send_sig_fault(SIGILL, ILL_COPROC, (void __user *)pc, 0, current);
+	send_sig_fault(SIGILL, ILL_COPROC, (void __user *)pc, current);
 }
 
 void handle_hw_divzero(struct pt_regs *regs, unsigned long pc, unsigned long npc,
 		       unsigned long psr)
 {
-	send_sig_fault(SIGFPE, FPE_INTDIV, (void __user *)pc, 0, current);
+	send_sig_fault(SIGFPE, FPE_INTDIV, (void __user *)pc, current);
 }
 
 #ifdef CONFIG_DEBUG_BUGVERBOSE
diff --git a/arch/sparc/kernel/traps_64.c b/arch/sparc/kernel/traps_64.c
index a850dccd78ea..6863025ed56d 100644
--- a/arch/sparc/kernel/traps_64.c
+++ b/arch/sparc/kernel/traps_64.c
@@ -107,8 +107,8 @@ void bad_trap(struct pt_regs *regs, long lvl)
 		regs->tpc &= 0xffffffff;
 		regs->tnpc &= 0xffffffff;
 	}
-	force_sig_fault(SIGILL, ILL_ILLTRP,
-			(void __user *)regs->tpc, lvl);
+	force_sig_fault_trapno(SIGILL, ILL_ILLTRP,
+			       (void __user *)regs->tpc, lvl);
 }
 
 void bad_trap_tl1(struct pt_regs *regs, long lvl)
@@ -201,8 +201,7 @@ void spitfire_insn_access_exception(struct pt_regs *regs, unsigned long sfsr, un
 		regs->tpc &= 0xffffffff;
 		regs->tnpc &= 0xffffffff;
 	}
-	force_sig_fault(SIGSEGV, SEGV_MAPERR,
-			(void __user *)regs->tpc, 0);
+	force_sig_fault(SIGSEGV, SEGV_MAPERR, (void __user *)regs->tpc);
 out:
 	exception_exit(prev_state);
 }
@@ -237,7 +236,7 @@ void sun4v_insn_access_exception(struct pt_regs *regs, unsigned long addr, unsig
 		regs->tpc &= 0xffffffff;
 		regs->tnpc &= 0xffffffff;
 	}
-	force_sig_fault(SIGSEGV, SEGV_MAPERR, (void __user *) addr, 0);
+	force_sig_fault(SIGSEGV, SEGV_MAPERR, (void __user *) addr);
 }
 
 void sun4v_insn_access_exception_tl1(struct pt_regs *regs, unsigned long addr, unsigned long type_ctx)
@@ -321,7 +320,7 @@ void spitfire_data_access_exception(struct pt_regs *regs, unsigned long sfsr, un
 	if (is_no_fault_exception(regs))
 		return;
 
-	force_sig_fault(SIGSEGV, SEGV_MAPERR, (void __user *)sfar, 0);
+	force_sig_fault(SIGSEGV, SEGV_MAPERR, (void __user *)sfar);
 out:
 	exception_exit(prev_state);
 }
@@ -385,13 +384,13 @@ void sun4v_data_access_exception(struct pt_regs *regs, unsigned long addr, unsig
 	 */
 	switch (type) {
 	case HV_FAULT_TYPE_INV_ASI:
-		force_sig_fault(SIGILL, ILL_ILLADR, (void __user *)addr, 0);
+		force_sig_fault(SIGILL, ILL_ILLADR, (void __user *)addr);
 		break;
 	case HV_FAULT_TYPE_MCD_DIS:
-		force_sig_fault(SIGSEGV, SEGV_ACCADI, (void __user *)addr, 0);
+		force_sig_fault(SIGSEGV, SEGV_ACCADI, (void __user *)addr);
 		break;
 	default:
-		force_sig_fault(SIGSEGV, SEGV_MAPERR, (void __user *)addr, 0);
+		force_sig_fault(SIGSEGV, SEGV_MAPERR, (void __user *)addr);
 		break;
 	}
 }
@@ -568,7 +567,7 @@ static void spitfire_ue_log(unsigned long afsr, unsigned long afar, unsigned lon
 		regs->tpc &= 0xffffffff;
 		regs->tnpc &= 0xffffffff;
 	}
-	force_sig_fault(SIGBUS, BUS_OBJERR, (void *)0, 0);
+	force_sig_fault(SIGBUS, BUS_OBJERR, (void *)0);
 }
 
 void spitfire_access_error(struct pt_regs *regs, unsigned long status_encoded, unsigned long afar)
@@ -2069,8 +2068,7 @@ void do_mcd_err(struct pt_regs *regs, struct sun4v_error_entry ent)
 	/* Send SIGSEGV to the userspace process with the right signal
 	 * code
 	 */
-	force_sig_fault(SIGSEGV, SEGV_ADIDERR, (void __user *)ent.err_raddr,
-			0);
+	force_sig_fault(SIGSEGV, SEGV_ADIDERR, (void __user *)ent.err_raddr);
 }
 
 /* We run with %pil set to PIL_NORMAL_MAX and PSTATE_IE enabled in %pstate.
@@ -2184,7 +2182,7 @@ bool sun4v_nonresum_error_user_handled(struct pt_regs *regs,
 	}
 	if (attrs & SUN4V_ERR_ATTRS_PIO) {
 		force_sig_fault(SIGBUS, BUS_ADRERR,
-				(void __user *)sun4v_get_vaddr(regs), 0);
+				(void __user *)sun4v_get_vaddr(regs));
 		return true;
 	}
 
@@ -2340,8 +2338,7 @@ static void do_fpe_common(struct pt_regs *regs)
 			else if (fsr & 0x01)
 				code = FPE_FLTRES;
 		}
-		force_sig_fault(SIGFPE, code,
-				(void __user *)regs->tpc, 0);
+		force_sig_fault(SIGFPE, code, (void __user *)regs->tpc);
 	}
 }
 
@@ -2395,8 +2392,7 @@ void do_tof(struct pt_regs *regs)
 		regs->tpc &= 0xffffffff;
 		regs->tnpc &= 0xffffffff;
 	}
-	force_sig_fault(SIGEMT, EMT_TAGOVF,
-			(void __user *)regs->tpc, 0);
+	force_sig_fault(SIGEMT, EMT_TAGOVF, (void __user *)regs->tpc);
 out:
 	exception_exit(prev_state);
 }
@@ -2415,8 +2411,7 @@ void do_div0(struct pt_regs *regs)
 		regs->tpc &= 0xffffffff;
 		regs->tnpc &= 0xffffffff;
 	}
-	force_sig_fault(SIGFPE, FPE_INTDIV,
-			(void __user *)regs->tpc, 0);
+	force_sig_fault(SIGFPE, FPE_INTDIV, (void __user *)regs->tpc);
 out:
 	exception_exit(prev_state);
 }
@@ -2612,7 +2607,7 @@ void do_illegal_instruction(struct pt_regs *regs)
 			}
 		}
 	}
-	force_sig_fault(SIGILL, ILL_ILLOPC, (void __user *)pc, 0);
+	force_sig_fault(SIGILL, ILL_ILLOPC, (void __user *)pc);
 out:
 	exception_exit(prev_state);
 }
@@ -2632,7 +2627,7 @@ void mem_address_unaligned(struct pt_regs *regs, unsigned long sfar, unsigned lo
 	if (is_no_fault_exception(regs))
 		return;
 
-	force_sig_fault(SIGBUS, BUS_ADRALN, (void __user *)sfar, 0);
+	force_sig_fault(SIGBUS, BUS_ADRALN, (void __user *)sfar);
 out:
 	exception_exit(prev_state);
 }
@@ -2650,7 +2645,7 @@ void sun4v_do_mna(struct pt_regs *regs, unsigned long addr, unsigned long type_c
 	if (is_no_fault_exception(regs))
 		return;
 
-	force_sig_fault(SIGBUS, BUS_ADRALN, (void __user *) addr, 0);
+	force_sig_fault(SIGBUS, BUS_ADRALN, (void __user *) addr);
 }
 
 /* sun4v_mem_corrupt_detect_precise() - Handle precise exception on an ADI
@@ -2697,7 +2692,7 @@ void sun4v_mem_corrupt_detect_precise(struct pt_regs *regs, unsigned long addr,
 		regs->tpc &= 0xffffffff;
 		regs->tnpc &= 0xffffffff;
 	}
-	force_sig_fault(SIGSEGV, SEGV_ADIPERR, (void __user *)addr, 0);
+	force_sig_fault(SIGSEGV, SEGV_ADIPERR, (void __user *)addr);
 }
 
 void do_privop(struct pt_regs *regs)
@@ -2712,8 +2707,7 @@ void do_privop(struct pt_regs *regs)
 		regs->tpc &= 0xffffffff;
 		regs->tnpc &= 0xffffffff;
 	}
-	force_sig_fault(SIGILL, ILL_PRVOPC,
-			(void __user *)regs->tpc, 0);
+	force_sig_fault(SIGILL, ILL_PRVOPC, (void __user *)regs->tpc);
 out:
 	exception_exit(prev_state);
 }
diff --git a/arch/sparc/kernel/unaligned_32.c b/arch/sparc/kernel/unaligned_32.c
index ef5c5207c9ff..455f0258c745 100644
--- a/arch/sparc/kernel/unaligned_32.c
+++ b/arch/sparc/kernel/unaligned_32.c
@@ -278,5 +278,5 @@ asmlinkage void user_unaligned_trap(struct pt_regs *regs, unsigned int insn)
 {
 	send_sig_fault(SIGBUS, BUS_ADRALN,
 		       (void __user *)safe_compute_effective_address(regs, insn),
-		       0, current);
+		       current);
 }
diff --git a/arch/sparc/mm/fault_32.c b/arch/sparc/mm/fault_32.c
index de2031c2b2d7..fa858626b85b 100644
--- a/arch/sparc/mm/fault_32.c
+++ b/arch/sparc/mm/fault_32.c
@@ -83,7 +83,7 @@ static void __do_fault_siginfo(int code, int sig, struct pt_regs *regs,
 		show_signal_msg(regs, sig, code,
 				addr, current);
 
-	force_sig_fault(sig, code, (void __user *) addr, 0);
+	force_sig_fault(sig, code, (void __user *) addr);
 }
 
 static unsigned long compute_si_addr(struct pt_regs *regs, int text_fault)
diff --git a/arch/sparc/mm/fault_64.c b/arch/sparc/mm/fault_64.c
index 0a6bcc85fba7..9a9652a15fed 100644
--- a/arch/sparc/mm/fault_64.c
+++ b/arch/sparc/mm/fault_64.c
@@ -176,7 +176,7 @@ static void do_fault_siginfo(int code, int sig, struct pt_regs *regs,
 	if (unlikely(show_unhandled_signals))
 		show_signal_msg(regs, sig, code, addr, current);
 
-	force_sig_fault(sig, code, (void __user *) addr, 0);
+	force_sig_fault(sig, code, (void __user *) addr);
 }
 
 static unsigned int get_fault_insn(struct pt_regs *regs, unsigned int insn)
diff --git a/include/linux/sched/signal.h b/include/linux/sched/signal.h
index 3f6a0fcaa10c..7daa425f3055 100644
--- a/include/linux/sched/signal.h
+++ b/include/linux/sched/signal.h
@@ -298,11 +298,6 @@ static inline void kernel_signal_stop(void)
 
 	schedule();
 }
-#ifdef __ARCH_SI_TRAPNO
-# define ___ARCH_SI_TRAPNO(_a1) , _a1
-#else
-# define ___ARCH_SI_TRAPNO(_a1)
-#endif
 #ifdef __ia64__
 # define ___ARCH_SI_IA64(_a1, _a2, _a3) , _a1, _a2, _a3
 #else
@@ -310,14 +305,11 @@ static inline void kernel_signal_stop(void)
 #endif
 
 int force_sig_fault_to_task(int sig, int code, void __user *addr
-	___ARCH_SI_TRAPNO(int trapno)
 	___ARCH_SI_IA64(int imm, unsigned int flags, unsigned long isr)
 	, struct task_struct *t);
 int force_sig_fault(int sig, int code, void __user *addr
-	___ARCH_SI_TRAPNO(int trapno)
 	___ARCH_SI_IA64(int imm, unsigned int flags, unsigned long isr));
 int send_sig_fault(int sig, int code, void __user *addr
-	___ARCH_SI_TRAPNO(int trapno)
 	___ARCH_SI_IA64(int imm, unsigned int flags, unsigned long isr)
 	, struct task_struct *t);
 
@@ -327,6 +319,10 @@ int send_sig_mceerr(int code, void __user *, short, struct task_struct *);
 int force_sig_bnderr(void __user *addr, void __user *lower, void __user *upper);
 int force_sig_pkuerr(void __user *addr, u32 pkey);
 
+int force_sig_fault_trapno(int sig, int code, void __user *addr, int trapno);
+int send_sig_fault_trapno(int sig, int code, void __user *addr, int trapno,
+			  struct task_struct *task);
+
 int force_sig_ptrace_errno_trap(int errno, void __user *addr);
 
 extern int send_sig_info(int, struct kernel_siginfo *, struct task_struct *);
diff --git a/kernel/signal.c b/kernel/signal.c
index 3d3ba7949788..7eaa8d84db4c 100644
--- a/kernel/signal.c
+++ b/kernel/signal.c
@@ -1651,7 +1651,6 @@ void force_sigsegv(int sig)
 }
 
 int force_sig_fault_to_task(int sig, int code, void __user *addr
-	___ARCH_SI_TRAPNO(int trapno)
 	___ARCH_SI_IA64(int imm, unsigned int flags, unsigned long isr)
 	, struct task_struct *t)
 {
@@ -1662,9 +1661,6 @@ int force_sig_fault_to_task(int sig, int code, void __user *addr
 	info.si_errno = 0;
 	info.si_code  = code;
 	info.si_addr  = addr;
-#ifdef __ARCH_SI_TRAPNO
-	info.si_trapno = trapno;
-#endif
 #ifdef __ia64__
 	info.si_imm = imm;
 	info.si_flags = flags;
@@ -1674,16 +1670,13 @@ int force_sig_fault_to_task(int sig, int code, void __user *addr
 }
 
 int force_sig_fault(int sig, int code, void __user *addr
-	___ARCH_SI_TRAPNO(int trapno)
 	___ARCH_SI_IA64(int imm, unsigned int flags, unsigned long isr))
 {
 	return force_sig_fault_to_task(sig, code, addr
-				       ___ARCH_SI_TRAPNO(trapno)
 				       ___ARCH_SI_IA64(imm, flags, isr), current);
 }
 
 int send_sig_fault(int sig, int code, void __user *addr
-	___ARCH_SI_TRAPNO(int trapno)
 	___ARCH_SI_IA64(int imm, unsigned int flags, unsigned long isr)
 	, struct task_struct *t)
 {
@@ -1694,9 +1687,6 @@ int send_sig_fault(int sig, int code, void __user *addr
 	info.si_errno = 0;
 	info.si_code  = code;
 	info.si_addr  = addr;
-#ifdef __ARCH_SI_TRAPNO
-	info.si_trapno = trapno;
-#endif
 #ifdef __ia64__
 	info.si_imm = imm;
 	info.si_flags = flags;
@@ -1763,6 +1753,37 @@ int force_sig_pkuerr(void __user *addr, u32 pkey)
 }
 #endif
 
+#if IS_ENABLED(CONFIG_SPARC)
+int force_sig_fault_trapno(int sig, int code, void __user *addr, int trapno)
+{
+	struct kernel_siginfo info;
+
+	clear_siginfo(&info);
+	info.si_signo = sig;
+	info.si_errno = 0;
+	info.si_code  = code;
+	info.si_addr  = addr;
+	info.si_trapno = trapno;
+	return force_sig_info(&info);
+}
+#endif
+
+#if IS_ENABLED(CONFIG_ALPHA)
+int send_sig_fault_trapno(int sig, int code, void __user *addr, int trapno,
+			  struct task_struct *t)
+{
+	struct kernel_siginfo info;
+
+	clear_siginfo(&info);
+	info.si_signo = sig;
+	info.si_errno = 0;
+	info.si_code  = code;
+	info.si_addr  = addr;
+	info.si_trapno = trapno;
+	return send_sig_info(info.si_signo, &info, t);
+}
+#endif
+
 /* For the crazy architectures that include trap information in
  * the errno field, instead of an actual errno value.
  */
-- 
2.30.1

Re: [PATCH v3 07/12] signal: Use dedicated helpers to send signals with si_trapno set

[Marco Elver]

On Wed, 5 May 2021 at 16:11, Eric W. Beiderman <ebiederm@xmission.com> wrote:
> From: "Eric W. Biederman" <ebiederm@xmission.com>
>
> Now that si_trapno is no longer expected to be present for every fault
> reported using siginfo on alpha and sparc remove the trapno parameter
> from force_sig_fault, force_sig_fault_to_task and send_sig_fault.
>
> Add two new helpers force_sig_fault_trapno and send_sig_fautl_trapno
> for those signals where trapno is expected to be set.
>
> v1: https://lkml.kernel.org/r/m1eeers7q7.fsf_-_@fess.ebiederm.org
> Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>

Reviewed-by: Marco Elver <elver@google.com>



> ---
>  arch/alpha/kernel/osf_sys.c      |  2 +-
>  arch/alpha/kernel/signal.c       |  4 +--
>  arch/alpha/kernel/traps.c        | 24 ++++++++---------
>  arch/alpha/mm/fault.c            |  4 +--
>  arch/sparc/kernel/process_64.c   |  2 +-
>  arch/sparc/kernel/sys_sparc_32.c |  2 +-
>  arch/sparc/kernel/sys_sparc_64.c |  2 +-
>  arch/sparc/kernel/traps_32.c     | 22 ++++++++--------
>  arch/sparc/kernel/traps_64.c     | 44 ++++++++++++++------------------
>  arch/sparc/kernel/unaligned_32.c |  2 +-
>  arch/sparc/mm/fault_32.c         |  2 +-
>  arch/sparc/mm/fault_64.c         |  2 +-
>  include/linux/sched/signal.h     | 12 +++------
>  kernel/signal.c                  | 41 +++++++++++++++++++++--------
>  14 files changed, 88 insertions(+), 77 deletions(-)
>
> diff --git a/arch/alpha/kernel/osf_sys.c b/arch/alpha/kernel/osf_sys.c
> index d5367a1c6300..80c5d7fbe66a 100644
> --- a/arch/alpha/kernel/osf_sys.c
> +++ b/arch/alpha/kernel/osf_sys.c
> @@ -878,7 +878,7 @@ SYSCALL_DEFINE5(osf_setsysinfo, unsigned long, op, void __user *, buffer,
>
>                         send_sig_fault(SIGFPE, si_code,
>                                        (void __user *)NULL,  /* FIXME */
> -                                      0, current);
> +                                      current);
>                 }
>                 return 0;
>         }
> diff --git a/arch/alpha/kernel/signal.c b/arch/alpha/kernel/signal.c
> index 948b89789da8..bc077babafab 100644
> --- a/arch/alpha/kernel/signal.c
> +++ b/arch/alpha/kernel/signal.c
> @@ -219,7 +219,7 @@ do_sigreturn(struct sigcontext __user *sc)
>
>         /* Send SIGTRAP if we're single-stepping: */
>         if (ptrace_cancel_bpt (current)) {
> -               send_sig_fault(SIGTRAP, TRAP_BRKPT, (void __user *) regs->pc, 0,
> +               send_sig_fault(SIGTRAP, TRAP_BRKPT, (void __user *) regs->pc,
>                                current);
>         }
>         return;
> @@ -247,7 +247,7 @@ do_rt_sigreturn(struct rt_sigframe __user *frame)
>
>         /* Send SIGTRAP if we're single-stepping: */
>         if (ptrace_cancel_bpt (current)) {
> -               send_sig_fault(SIGTRAP, TRAP_BRKPT, (void __user *) regs->pc, 0,
> +               send_sig_fault(SIGTRAP, TRAP_BRKPT, (void __user *) regs->pc,
>                                current);
>         }
>         return;
> diff --git a/arch/alpha/kernel/traps.c b/arch/alpha/kernel/traps.c
> index 921d4b6e4d95..0dddf9ecc1f4 100644
> --- a/arch/alpha/kernel/traps.c
> +++ b/arch/alpha/kernel/traps.c
> @@ -227,7 +227,7 @@ do_entArith(unsigned long summary, unsigned long write_mask,
>         }
>         die_if_kernel("Arithmetic fault", regs, 0, NULL);
>
> -       send_sig_fault(SIGFPE, si_code, (void __user *) regs->pc, 0, current);
> +       send_sig_fault_trapno(SIGFPE, si_code, (void __user *) regs->pc, 0, current);
>  }
>
>  asmlinkage void
> @@ -268,12 +268,12 @@ do_entIF(unsigned long type, struct pt_regs *regs)
>                         regs->pc -= 4;  /* make pc point to former bpt */
>                 }
>
> -               send_sig_fault(SIGTRAP, TRAP_BRKPT, (void __user *)regs->pc, 0,
> +               send_sig_fault(SIGTRAP, TRAP_BRKPT, (void __user *)regs->pc,
>                                current);
>                 return;
>
>               case 1: /* bugcheck */
> -               send_sig_fault(SIGTRAP, TRAP_UNK, (void __user *) regs->pc, 0,
> +               send_sig_fault(SIGTRAP, TRAP_UNK, (void __user *) regs->pc,
>                                current);
>                 return;
>
> @@ -335,8 +335,8 @@ do_entIF(unsigned long type, struct pt_regs *regs)
>                         break;
>                 }
>
> -               send_sig_fault(signo, code, (void __user *) regs->pc, regs->r16,
> -                              current);
> +               send_sig_fault_trapno(signo, code, (void __user *) regs->pc,
> +                                     regs->r16, current);
>                 return;
>
>               case 4: /* opDEC */
> @@ -360,9 +360,9 @@ do_entIF(unsigned long type, struct pt_regs *regs)
>                         if (si_code == 0)
>                                 return;
>                         if (si_code > 0) {
> -                               send_sig_fault(SIGFPE, si_code,
> -                                              (void __user *) regs->pc, 0,
> -                                              current);
> +                               send_sig_fault_trapno(SIGFPE, si_code,
> +                                                     (void __user *) regs->pc,
> +                                                     0, current);
>                                 return;
>                         }
>                 }
> @@ -387,7 +387,7 @@ do_entIF(unsigned long type, struct pt_regs *regs)
>                       ;
>         }
>
> -       send_sig_fault(SIGILL, ILL_ILLOPC, (void __user *)regs->pc, 0, current);
> +       send_sig_fault(SIGILL, ILL_ILLOPC, (void __user *)regs->pc, current);
>  }
>
>  /* There is an ifdef in the PALcode in MILO that enables a
> @@ -402,7 +402,7 @@ do_entDbg(struct pt_regs *regs)
>  {
>         die_if_kernel("Instruction fault", regs, 0, NULL);
>
> -       force_sig_fault(SIGILL, ILL_ILLOPC, (void __user *)regs->pc, 0);
> +       force_sig_fault(SIGILL, ILL_ILLOPC, (void __user *)regs->pc);
>  }
>
>
> @@ -964,12 +964,12 @@ do_entUnaUser(void __user * va, unsigned long opcode,
>                         si_code = SEGV_MAPERR;
>                 mmap_read_unlock(mm);
>         }
> -       send_sig_fault(SIGSEGV, si_code, va, 0, current);
> +       send_sig_fault(SIGSEGV, si_code, va, current);
>         return;
>
>  give_sigbus:
>         regs->pc -= 4;
> -       send_sig_fault(SIGBUS, BUS_ADRALN, va, 0, current);
> +       send_sig_fault(SIGBUS, BUS_ADRALN, va, current);
>         return;
>  }
>
> diff --git a/arch/alpha/mm/fault.c b/arch/alpha/mm/fault.c
> index 09172f017efc..eee5102c3d88 100644
> --- a/arch/alpha/mm/fault.c
> +++ b/arch/alpha/mm/fault.c
> @@ -219,13 +219,13 @@ do_page_fault(unsigned long address, unsigned long mmcsr,
>         mmap_read_unlock(mm);
>         /* Send a sigbus, regardless of whether we were in kernel
>            or user mode.  */
> -       force_sig_fault(SIGBUS, BUS_ADRERR, (void __user *) address, 0);
> +       force_sig_fault(SIGBUS, BUS_ADRERR, (void __user *) address);
>         if (!user_mode(regs))
>                 goto no_context;
>         return;
>
>   do_sigsegv:
> -       force_sig_fault(SIGSEGV, si_code, (void __user *) address, 0);
> +       force_sig_fault(SIGSEGV, si_code, (void __user *) address);
>         return;
>
>  #ifdef CONFIG_ALPHA_LARGE_VMALLOC
> diff --git a/arch/sparc/kernel/process_64.c b/arch/sparc/kernel/process_64.c
> index 7afd0a859a78..29e67854d5a4 100644
> --- a/arch/sparc/kernel/process_64.c
> +++ b/arch/sparc/kernel/process_64.c
> @@ -518,7 +518,7 @@ void synchronize_user_stack(void)
>
>  static void stack_unaligned(unsigned long sp)
>  {
> -       force_sig_fault(SIGBUS, BUS_ADRALN, (void __user *) sp, 0);
> +       force_sig_fault(SIGBUS, BUS_ADRALN, (void __user *) sp);
>  }
>
>  static const char uwfault32[] = KERN_INFO \
> diff --git a/arch/sparc/kernel/sys_sparc_32.c b/arch/sparc/kernel/sys_sparc_32.c
> index be77538bc038..082a551897ed 100644
> --- a/arch/sparc/kernel/sys_sparc_32.c
> +++ b/arch/sparc/kernel/sys_sparc_32.c
> @@ -151,7 +151,7 @@ sparc_breakpoint (struct pt_regs *regs)
>  #ifdef DEBUG_SPARC_BREAKPOINT
>          printk ("TRAP: Entering kernel PC=%x, nPC=%x\n", regs->pc, regs->npc);
>  #endif
> -       force_sig_fault(SIGTRAP, TRAP_BRKPT, (void __user *)regs->pc, 0);
> +       force_sig_fault(SIGTRAP, TRAP_BRKPT, (void __user *)regs->pc);
>
>  #ifdef DEBUG_SPARC_BREAKPOINT
>         printk ("TRAP: Returning to space: PC=%x nPC=%x\n", regs->pc, regs->npc);
> diff --git a/arch/sparc/kernel/sys_sparc_64.c b/arch/sparc/kernel/sys_sparc_64.c
> index 6b92fadb6ec7..1e9a9e016237 100644
> --- a/arch/sparc/kernel/sys_sparc_64.c
> +++ b/arch/sparc/kernel/sys_sparc_64.c
> @@ -514,7 +514,7 @@ asmlinkage void sparc_breakpoint(struct pt_regs *regs)
>  #ifdef DEBUG_SPARC_BREAKPOINT
>          printk ("TRAP: Entering kernel PC=%lx, nPC=%lx\n", regs->tpc, regs->tnpc);
>  #endif
> -       force_sig_fault(SIGTRAP, TRAP_BRKPT, (void __user *)regs->tpc, 0);
> +       force_sig_fault(SIGTRAP, TRAP_BRKPT, (void __user *)regs->tpc);
>  #ifdef DEBUG_SPARC_BREAKPOINT
>         printk ("TRAP: Returning to space: PC=%lx nPC=%lx\n", regs->tpc, regs->tnpc);
>  #endif
> diff --git a/arch/sparc/kernel/traps_32.c b/arch/sparc/kernel/traps_32.c
> index 247a0d9683b2..5630e5a395e0 100644
> --- a/arch/sparc/kernel/traps_32.c
> +++ b/arch/sparc/kernel/traps_32.c
> @@ -102,8 +102,8 @@ void do_hw_interrupt(struct pt_regs *regs, unsigned long type)
>         if(regs->psr & PSR_PS)
>                 die_if_kernel("Kernel bad trap", regs);
>
> -       force_sig_fault(SIGILL, ILL_ILLTRP,
> -                       (void __user *)regs->pc, type - 0x80);
> +       force_sig_fault_trapno(SIGILL, ILL_ILLTRP,
> +                              (void __user *)regs->pc, type - 0x80);
>  }
>
>  void do_illegal_instruction(struct pt_regs *regs, unsigned long pc, unsigned long npc,
> @@ -116,7 +116,7 @@ void do_illegal_instruction(struct pt_regs *regs, unsigned long pc, unsigned lon
>                regs->pc, *(unsigned long *)regs->pc);
>  #endif
>
> -       send_sig_fault(SIGILL, ILL_ILLOPC, (void __user *)pc, 0, current);
> +       send_sig_fault(SIGILL, ILL_ILLOPC, (void __user *)pc, current);
>  }
>
>  void do_priv_instruction(struct pt_regs *regs, unsigned long pc, unsigned long npc,
> @@ -124,7 +124,7 @@ void do_priv_instruction(struct pt_regs *regs, unsigned long pc, unsigned long n
>  {
>         if(psr & PSR_PS)
>                 die_if_kernel("Penguin instruction from Penguin mode??!?!", regs);
> -       send_sig_fault(SIGILL, ILL_PRVOPC, (void __user *)pc, 0, current);
> +       send_sig_fault(SIGILL, ILL_PRVOPC, (void __user *)pc, current);
>  }
>
>  /* XXX User may want to be allowed to do this. XXX */
> @@ -145,7 +145,7 @@ void do_memaccess_unaligned(struct pt_regs *regs, unsigned long pc, unsigned lon
>  #endif
>         send_sig_fault(SIGBUS, BUS_ADRALN,
>                        /* FIXME: Should dig out mna address */ (void *)0,
> -                      0, current);
> +                      current);
>  }
>
>  static unsigned long init_fsr = 0x0UL;
> @@ -291,7 +291,7 @@ void do_fpe_trap(struct pt_regs *regs, unsigned long pc, unsigned long npc,
>                 else if (fsr & 0x01)
>                         code = FPE_FLTRES;
>         }
> -       send_sig_fault(SIGFPE, code, (void __user *)pc, 0, fpt);
> +       send_sig_fault(SIGFPE, code, (void __user *)pc, fpt);
>  #ifndef CONFIG_SMP
>         last_task_used_math = NULL;
>  #endif
> @@ -305,7 +305,7 @@ void handle_tag_overflow(struct pt_regs *regs, unsigned long pc, unsigned long n
>  {
>         if(psr & PSR_PS)
>                 die_if_kernel("Penguin overflow trap from kernel mode", regs);
> -       send_sig_fault(SIGEMT, EMT_TAGOVF, (void __user *)pc, 0, current);
> +       send_sig_fault(SIGEMT, EMT_TAGOVF, (void __user *)pc, current);
>  }
>
>  void handle_watchpoint(struct pt_regs *regs, unsigned long pc, unsigned long npc,
> @@ -327,13 +327,13 @@ void handle_reg_access(struct pt_regs *regs, unsigned long pc, unsigned long npc
>         printk("Register Access Exception at PC %08lx NPC %08lx PSR %08lx\n",
>                pc, npc, psr);
>  #endif
> -       force_sig_fault(SIGBUS, BUS_OBJERR, (void __user *)pc, 0);
> +       force_sig_fault(SIGBUS, BUS_OBJERR, (void __user *)pc);
>  }
>
>  void handle_cp_disabled(struct pt_regs *regs, unsigned long pc, unsigned long npc,
>                         unsigned long psr)
>  {
> -       send_sig_fault(SIGILL, ILL_COPROC, (void __user *)pc, 0, current);
> +       send_sig_fault(SIGILL, ILL_COPROC, (void __user *)pc, current);
>  }
>
>  void handle_cp_exception(struct pt_regs *regs, unsigned long pc, unsigned long npc,
> @@ -343,13 +343,13 @@ void handle_cp_exception(struct pt_regs *regs, unsigned long pc, unsigned long n
>         printk("Co-Processor Exception at PC %08lx NPC %08lx PSR %08lx\n",
>                pc, npc, psr);
>  #endif
> -       send_sig_fault(SIGILL, ILL_COPROC, (void __user *)pc, 0, current);
> +       send_sig_fault(SIGILL, ILL_COPROC, (void __user *)pc, current);
>  }
>
>  void handle_hw_divzero(struct pt_regs *regs, unsigned long pc, unsigned long npc,
>                        unsigned long psr)
>  {
> -       send_sig_fault(SIGFPE, FPE_INTDIV, (void __user *)pc, 0, current);
> +       send_sig_fault(SIGFPE, FPE_INTDIV, (void __user *)pc, current);
>  }
>
>  #ifdef CONFIG_DEBUG_BUGVERBOSE
> diff --git a/arch/sparc/kernel/traps_64.c b/arch/sparc/kernel/traps_64.c
> index a850dccd78ea..6863025ed56d 100644
> --- a/arch/sparc/kernel/traps_64.c
> +++ b/arch/sparc/kernel/traps_64.c
> @@ -107,8 +107,8 @@ void bad_trap(struct pt_regs *regs, long lvl)
>                 regs->tpc &= 0xffffffff;
>                 regs->tnpc &= 0xffffffff;
>         }
> -       force_sig_fault(SIGILL, ILL_ILLTRP,
> -                       (void __user *)regs->tpc, lvl);
> +       force_sig_fault_trapno(SIGILL, ILL_ILLTRP,
> +                              (void __user *)regs->tpc, lvl);
>  }
>
>  void bad_trap_tl1(struct pt_regs *regs, long lvl)
> @@ -201,8 +201,7 @@ void spitfire_insn_access_exception(struct pt_regs *regs, unsigned long sfsr, un
>                 regs->tpc &= 0xffffffff;
>                 regs->tnpc &= 0xffffffff;
>         }
> -       force_sig_fault(SIGSEGV, SEGV_MAPERR,
> -                       (void __user *)regs->tpc, 0);
> +       force_sig_fault(SIGSEGV, SEGV_MAPERR, (void __user *)regs->tpc);
>  out:
>         exception_exit(prev_state);
>  }
> @@ -237,7 +236,7 @@ void sun4v_insn_access_exception(struct pt_regs *regs, unsigned long addr, unsig
>                 regs->tpc &= 0xffffffff;
>                 regs->tnpc &= 0xffffffff;
>         }
> -       force_sig_fault(SIGSEGV, SEGV_MAPERR, (void __user *) addr, 0);
> +       force_sig_fault(SIGSEGV, SEGV_MAPERR, (void __user *) addr);
>  }
>
>  void sun4v_insn_access_exception_tl1(struct pt_regs *regs, unsigned long addr, unsigned long type_ctx)
> @@ -321,7 +320,7 @@ void spitfire_data_access_exception(struct pt_regs *regs, unsigned long sfsr, un
>         if (is_no_fault_exception(regs))
>                 return;
>
> -       force_sig_fault(SIGSEGV, SEGV_MAPERR, (void __user *)sfar, 0);
> +       force_sig_fault(SIGSEGV, SEGV_MAPERR, (void __user *)sfar);
>  out:
>         exception_exit(prev_state);
>  }
> @@ -385,13 +384,13 @@ void sun4v_data_access_exception(struct pt_regs *regs, unsigned long addr, unsig
>          */
>         switch (type) {
>         case HV_FAULT_TYPE_INV_ASI:
> -               force_sig_fault(SIGILL, ILL_ILLADR, (void __user *)addr, 0);
> +               force_sig_fault(SIGILL, ILL_ILLADR, (void __user *)addr);
>                 break;
>         case HV_FAULT_TYPE_MCD_DIS:
> -               force_sig_fault(SIGSEGV, SEGV_ACCADI, (void __user *)addr, 0);
> +               force_sig_fault(SIGSEGV, SEGV_ACCADI, (void __user *)addr);
>                 break;
>         default:
> -               force_sig_fault(SIGSEGV, SEGV_MAPERR, (void __user *)addr, 0);
> +               force_sig_fault(SIGSEGV, SEGV_MAPERR, (void __user *)addr);
>                 break;
>         }
>  }
> @@ -568,7 +567,7 @@ static void spitfire_ue_log(unsigned long afsr, unsigned long afar, unsigned lon
>                 regs->tpc &= 0xffffffff;
>                 regs->tnpc &= 0xffffffff;
>         }
> -       force_sig_fault(SIGBUS, BUS_OBJERR, (void *)0, 0);
> +       force_sig_fault(SIGBUS, BUS_OBJERR, (void *)0);
>  }
>
>  void spitfire_access_error(struct pt_regs *regs, unsigned long status_encoded, unsigned long afar)
> @@ -2069,8 +2068,7 @@ void do_mcd_err(struct pt_regs *regs, struct sun4v_error_entry ent)
>         /* Send SIGSEGV to the userspace process with the right signal
>          * code
>          */
> -       force_sig_fault(SIGSEGV, SEGV_ADIDERR, (void __user *)ent.err_raddr,
> -                       0);
> +       force_sig_fault(SIGSEGV, SEGV_ADIDERR, (void __user *)ent.err_raddr);
>  }
>
>  /* We run with %pil set to PIL_NORMAL_MAX and PSTATE_IE enabled in %pstate.
> @@ -2184,7 +2182,7 @@ bool sun4v_nonresum_error_user_handled(struct pt_regs *regs,
>         }
>         if (attrs & SUN4V_ERR_ATTRS_PIO) {
>                 force_sig_fault(SIGBUS, BUS_ADRERR,
> -                               (void __user *)sun4v_get_vaddr(regs), 0);
> +                               (void __user *)sun4v_get_vaddr(regs));
>                 return true;
>         }
>
> @@ -2340,8 +2338,7 @@ static void do_fpe_common(struct pt_regs *regs)
>                         else if (fsr & 0x01)
>                                 code = FPE_FLTRES;
>                 }
> -               force_sig_fault(SIGFPE, code,
> -                               (void __user *)regs->tpc, 0);
> +               force_sig_fault(SIGFPE, code, (void __user *)regs->tpc);
>         }
>  }
>
> @@ -2395,8 +2392,7 @@ void do_tof(struct pt_regs *regs)
>                 regs->tpc &= 0xffffffff;
>                 regs->tnpc &= 0xffffffff;
>         }
> -       force_sig_fault(SIGEMT, EMT_TAGOVF,
> -                       (void __user *)regs->tpc, 0);
> +       force_sig_fault(SIGEMT, EMT_TAGOVF, (void __user *)regs->tpc);
>  out:
>         exception_exit(prev_state);
>  }
> @@ -2415,8 +2411,7 @@ void do_div0(struct pt_regs *regs)
>                 regs->tpc &= 0xffffffff;
>                 regs->tnpc &= 0xffffffff;
>         }
> -       force_sig_fault(SIGFPE, FPE_INTDIV,
> -                       (void __user *)regs->tpc, 0);
> +       force_sig_fault(SIGFPE, FPE_INTDIV, (void __user *)regs->tpc);
>  out:
>         exception_exit(prev_state);
>  }
> @@ -2612,7 +2607,7 @@ void do_illegal_instruction(struct pt_regs *regs)
>                         }
>                 }
>         }
> -       force_sig_fault(SIGILL, ILL_ILLOPC, (void __user *)pc, 0);
> +       force_sig_fault(SIGILL, ILL_ILLOPC, (void __user *)pc);
>  out:
>         exception_exit(prev_state);
>  }
> @@ -2632,7 +2627,7 @@ void mem_address_unaligned(struct pt_regs *regs, unsigned long sfar, unsigned lo
>         if (is_no_fault_exception(regs))
>                 return;
>
> -       force_sig_fault(SIGBUS, BUS_ADRALN, (void __user *)sfar, 0);
> +       force_sig_fault(SIGBUS, BUS_ADRALN, (void __user *)sfar);
>  out:
>         exception_exit(prev_state);
>  }
> @@ -2650,7 +2645,7 @@ void sun4v_do_mna(struct pt_regs *regs, unsigned long addr, unsigned long type_c
>         if (is_no_fault_exception(regs))
>                 return;
>
> -       force_sig_fault(SIGBUS, BUS_ADRALN, (void __user *) addr, 0);
> +       force_sig_fault(SIGBUS, BUS_ADRALN, (void __user *) addr);
>  }
>
>  /* sun4v_mem_corrupt_detect_precise() - Handle precise exception on an ADI
> @@ -2697,7 +2692,7 @@ void sun4v_mem_corrupt_detect_precise(struct pt_regs *regs, unsigned long addr,
>                 regs->tpc &= 0xffffffff;
>                 regs->tnpc &= 0xffffffff;
>         }
> -       force_sig_fault(SIGSEGV, SEGV_ADIPERR, (void __user *)addr, 0);
> +       force_sig_fault(SIGSEGV, SEGV_ADIPERR, (void __user *)addr);
>  }
>
>  void do_privop(struct pt_regs *regs)
> @@ -2712,8 +2707,7 @@ void do_privop(struct pt_regs *regs)
>                 regs->tpc &= 0xffffffff;
>                 regs->tnpc &= 0xffffffff;
>         }
> -       force_sig_fault(SIGILL, ILL_PRVOPC,
> -                       (void __user *)regs->tpc, 0);
> +       force_sig_fault(SIGILL, ILL_PRVOPC, (void __user *)regs->tpc);
>  out:
>         exception_exit(prev_state);
>  }
> diff --git a/arch/sparc/kernel/unaligned_32.c b/arch/sparc/kernel/unaligned_32.c
> index ef5c5207c9ff..455f0258c745 100644
> --- a/arch/sparc/kernel/unaligned_32.c
> +++ b/arch/sparc/kernel/unaligned_32.c
> @@ -278,5 +278,5 @@ asmlinkage void user_unaligned_trap(struct pt_regs *regs, unsigned int insn)
>  {
>         send_sig_fault(SIGBUS, BUS_ADRALN,
>                        (void __user *)safe_compute_effective_address(regs, insn),
> -                      0, current);
> +                      current);
>  }
> diff --git a/arch/sparc/mm/fault_32.c b/arch/sparc/mm/fault_32.c
> index de2031c2b2d7..fa858626b85b 100644
> --- a/arch/sparc/mm/fault_32.c
> +++ b/arch/sparc/mm/fault_32.c
> @@ -83,7 +83,7 @@ static void __do_fault_siginfo(int code, int sig, struct pt_regs *regs,
>                 show_signal_msg(regs, sig, code,
>                                 addr, current);
>
> -       force_sig_fault(sig, code, (void __user *) addr, 0);
> +       force_sig_fault(sig, code, (void __user *) addr);
>  }
>
>  static unsigned long compute_si_addr(struct pt_regs *regs, int text_fault)
> diff --git a/arch/sparc/mm/fault_64.c b/arch/sparc/mm/fault_64.c
> index 0a6bcc85fba7..9a9652a15fed 100644
> --- a/arch/sparc/mm/fault_64.c
> +++ b/arch/sparc/mm/fault_64.c
> @@ -176,7 +176,7 @@ static void do_fault_siginfo(int code, int sig, struct pt_regs *regs,
>         if (unlikely(show_unhandled_signals))
>                 show_signal_msg(regs, sig, code, addr, current);
>
> -       force_sig_fault(sig, code, (void __user *) addr, 0);
> +       force_sig_fault(sig, code, (void __user *) addr);
>  }
>
>  static unsigned int get_fault_insn(struct pt_regs *regs, unsigned int insn)
> diff --git a/include/linux/sched/signal.h b/include/linux/sched/signal.h
> index 3f6a0fcaa10c..7daa425f3055 100644
> --- a/include/linux/sched/signal.h
> +++ b/include/linux/sched/signal.h
> @@ -298,11 +298,6 @@ static inline void kernel_signal_stop(void)
>
>         schedule();
>  }
> -#ifdef __ARCH_SI_TRAPNO
> -# define ___ARCH_SI_TRAPNO(_a1) , _a1
> -#else
> -# define ___ARCH_SI_TRAPNO(_a1)
> -#endif
>  #ifdef __ia64__
>  # define ___ARCH_SI_IA64(_a1, _a2, _a3) , _a1, _a2, _a3
>  #else
> @@ -310,14 +305,11 @@ static inline void kernel_signal_stop(void)
>  #endif
>
>  int force_sig_fault_to_task(int sig, int code, void __user *addr
> -       ___ARCH_SI_TRAPNO(int trapno)
>         ___ARCH_SI_IA64(int imm, unsigned int flags, unsigned long isr)
>         , struct task_struct *t);
>  int force_sig_fault(int sig, int code, void __user *addr
> -       ___ARCH_SI_TRAPNO(int trapno)
>         ___ARCH_SI_IA64(int imm, unsigned int flags, unsigned long isr));
>  int send_sig_fault(int sig, int code, void __user *addr
> -       ___ARCH_SI_TRAPNO(int trapno)
>         ___ARCH_SI_IA64(int imm, unsigned int flags, unsigned long isr)
>         , struct task_struct *t);
>
> @@ -327,6 +319,10 @@ int send_sig_mceerr(int code, void __user *, short, struct task_struct *);
>  int force_sig_bnderr(void __user *addr, void __user *lower, void __user *upper);
>  int force_sig_pkuerr(void __user *addr, u32 pkey);
>
> +int force_sig_fault_trapno(int sig, int code, void __user *addr, int trapno);
> +int send_sig_fault_trapno(int sig, int code, void __user *addr, int trapno,
> +                         struct task_struct *task);
> +
>  int force_sig_ptrace_errno_trap(int errno, void __user *addr);
>
>  extern int send_sig_info(int, struct kernel_siginfo *, struct task_struct *);
> diff --git a/kernel/signal.c b/kernel/signal.c
> index 3d3ba7949788..7eaa8d84db4c 100644
> --- a/kernel/signal.c
> +++ b/kernel/signal.c
> @@ -1651,7 +1651,6 @@ void force_sigsegv(int sig)
>  }
>
>  int force_sig_fault_to_task(int sig, int code, void __user *addr
> -       ___ARCH_SI_TRAPNO(int trapno)
>         ___ARCH_SI_IA64(int imm, unsigned int flags, unsigned long isr)
>         , struct task_struct *t)
>  {
> @@ -1662,9 +1661,6 @@ int force_sig_fault_to_task(int sig, int code, void __user *addr
>         info.si_errno = 0;
>         info.si_code  = code;
>         info.si_addr  = addr;
> -#ifdef __ARCH_SI_TRAPNO
> -       info.si_trapno = trapno;
> -#endif
>  #ifdef __ia64__
>         info.si_imm = imm;
>         info.si_flags = flags;
> @@ -1674,16 +1670,13 @@ int force_sig_fault_to_task(int sig, int code, void __user *addr
>  }
>
>  int force_sig_fault(int sig, int code, void __user *addr
> -       ___ARCH_SI_TRAPNO(int trapno)
>         ___ARCH_SI_IA64(int imm, unsigned int flags, unsigned long isr))
>  {
>         return force_sig_fault_to_task(sig, code, addr
> -                                      ___ARCH_SI_TRAPNO(trapno)
>                                        ___ARCH_SI_IA64(imm, flags, isr), current);
>  }
>
>  int send_sig_fault(int sig, int code, void __user *addr
> -       ___ARCH_SI_TRAPNO(int trapno)
>         ___ARCH_SI_IA64(int imm, unsigned int flags, unsigned long isr)
>         , struct task_struct *t)
>  {
> @@ -1694,9 +1687,6 @@ int send_sig_fault(int sig, int code, void __user *addr
>         info.si_errno = 0;
>         info.si_code  = code;
>         info.si_addr  = addr;
> -#ifdef __ARCH_SI_TRAPNO
> -       info.si_trapno = trapno;
> -#endif
>  #ifdef __ia64__
>         info.si_imm = imm;
>         info.si_flags = flags;
> @@ -1763,6 +1753,37 @@ int force_sig_pkuerr(void __user *addr, u32 pkey)
>  }
>  #endif
>
> +#if IS_ENABLED(CONFIG_SPARC)
> +int force_sig_fault_trapno(int sig, int code, void __user *addr, int trapno)
> +{
> +       struct kernel_siginfo info;
> +
> +       clear_siginfo(&info);
> +       info.si_signo = sig;
> +       info.si_errno = 0;
> +       info.si_code  = code;
> +       info.si_addr  = addr;
> +       info.si_trapno = trapno;
> +       return force_sig_info(&info);
> +}
> +#endif
> +
> +#if IS_ENABLED(CONFIG_ALPHA)
> +int send_sig_fault_trapno(int sig, int code, void __user *addr, int trapno,
> +                         struct task_struct *t)
> +{
> +       struct kernel_siginfo info;
> +
> +       clear_siginfo(&info);
> +       info.si_signo = sig;
> +       info.si_errno = 0;
> +       info.si_code  = code;
> +       info.si_addr  = addr;
> +       info.si_trapno = trapno;
> +       return send_sig_info(info.si_signo, &info, t);
> +}
> +#endif
> +
>  /* For the crazy architectures that include trap information in
>   * the errno field, instead of an actual errno value.
>   */
> --
> 2.30.1

[PATCH v3 08/12] signal: Remove __ARCH_SI_TRAPNO

[Eric W. Beiderman]

From: "Eric W. Biederman" <ebiederm@xmission.com>

Now that this define is no longer used remove it from the kernel.

v1: https://lkml.kernel.org/r/m18s4zs7nu.fsf_-_@fess.ebiederm.org
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
---
 arch/alpha/include/uapi/asm/siginfo.h | 2 --
 arch/mips/include/uapi/asm/siginfo.h  | 2 --
 arch/sparc/include/uapi/asm/siginfo.h | 3 ---
 3 files changed, 7 deletions(-)

diff --git a/arch/alpha/include/uapi/asm/siginfo.h b/arch/alpha/include/uapi/asm/siginfo.h
index 6e1a2af2f962..e08eae88182b 100644
--- a/arch/alpha/include/uapi/asm/siginfo.h
+++ b/arch/alpha/include/uapi/asm/siginfo.h
@@ -2,8 +2,6 @@
 #ifndef _ALPHA_SIGINFO_H
 #define _ALPHA_SIGINFO_H
 
-#define __ARCH_SI_TRAPNO
-
 #include <asm-generic/siginfo.h>
 
 #endif
diff --git a/arch/mips/include/uapi/asm/siginfo.h b/arch/mips/include/uapi/asm/siginfo.h
index c34c7eef0a1c..8cb8bd061a68 100644
--- a/arch/mips/include/uapi/asm/siginfo.h
+++ b/arch/mips/include/uapi/asm/siginfo.h
@@ -10,9 +10,7 @@
 #ifndef _UAPI_ASM_SIGINFO_H
 #define _UAPI_ASM_SIGINFO_H
 
-
 #define __ARCH_SIGEV_PREAMBLE_SIZE (sizeof(long) + 2*sizeof(int))
-#undef __ARCH_SI_TRAPNO /* exception code needs to fill this ...  */
 
 #define __ARCH_HAS_SWAPPED_SIGINFO
 
diff --git a/arch/sparc/include/uapi/asm/siginfo.h b/arch/sparc/include/uapi/asm/siginfo.h
index 68bdde4c2a2e..0e7c27522aed 100644
--- a/arch/sparc/include/uapi/asm/siginfo.h
+++ b/arch/sparc/include/uapi/asm/siginfo.h
@@ -8,9 +8,6 @@
 
 #endif /* defined(__sparc__) && defined(__arch64__) */
 
-
-#define __ARCH_SI_TRAPNO
-
 #include <asm-generic/siginfo.h>
 
 
-- 
2.30.1

Re: [PATCH v3 08/12] signal: Remove __ARCH_SI_TRAPNO

[Marco Elver]

On Wed, 5 May 2021 at 16:11, Eric W. Beiderman <ebiederm@xmission.com> wrote:
> From: "Eric W. Biederman" <ebiederm@xmission.com>
>
> Now that this define is no longer used remove it from the kernel.
>
> v1: https://lkml.kernel.org/r/m18s4zs7nu.fsf_-_@fess.ebiederm.org
> Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>

Reviewed-by: Marco Elver <elver@google.com>



> ---
>  arch/alpha/include/uapi/asm/siginfo.h | 2 --
>  arch/mips/include/uapi/asm/siginfo.h  | 2 --
>  arch/sparc/include/uapi/asm/siginfo.h | 3 ---
>  3 files changed, 7 deletions(-)
>
> diff --git a/arch/alpha/include/uapi/asm/siginfo.h b/arch/alpha/include/uapi/asm/siginfo.h
> index 6e1a2af2f962..e08eae88182b 100644
> --- a/arch/alpha/include/uapi/asm/siginfo.h
> +++ b/arch/alpha/include/uapi/asm/siginfo.h
> @@ -2,8 +2,6 @@
>  #ifndef _ALPHA_SIGINFO_H
>  #define _ALPHA_SIGINFO_H
>
> -#define __ARCH_SI_TRAPNO
> -
>  #include <asm-generic/siginfo.h>
>
>  #endif
> diff --git a/arch/mips/include/uapi/asm/siginfo.h b/arch/mips/include/uapi/asm/siginfo.h
> index c34c7eef0a1c..8cb8bd061a68 100644
> --- a/arch/mips/include/uapi/asm/siginfo.h
> +++ b/arch/mips/include/uapi/asm/siginfo.h
> @@ -10,9 +10,7 @@
>  #ifndef _UAPI_ASM_SIGINFO_H
>  #define _UAPI_ASM_SIGINFO_H
>
> -
>  #define __ARCH_SIGEV_PREAMBLE_SIZE (sizeof(long) + 2*sizeof(int))
> -#undef __ARCH_SI_TRAPNO /* exception code needs to fill this ...  */
>
>  #define __ARCH_HAS_SWAPPED_SIGINFO
>
> diff --git a/arch/sparc/include/uapi/asm/siginfo.h b/arch/sparc/include/uapi/asm/siginfo.h
> index 68bdde4c2a2e..0e7c27522aed 100644
> --- a/arch/sparc/include/uapi/asm/siginfo.h
> +++ b/arch/sparc/include/uapi/asm/siginfo.h
> @@ -8,9 +8,6 @@
>
>  #endif /* defined(__sparc__) && defined(__arch64__) */
>
> -
> -#define __ARCH_SI_TRAPNO
> -
>  #include <asm-generic/siginfo.h>
>
>
> --
> 2.30.1

[PATCH v3 09/12] signal: Rename SIL_PERF_EVENT SIL_FAULT_PERF_EVENT for consistency

[Eric W. Beiderman]

From: "Eric W. Biederman" <ebiederm@xmission.com>

It helps to know which part of the siginfo structure the siginfo_layout
value is talking about.

v1: https://lkml.kernel.org/r/m18s4zs7nu.fsf_-_@fess.ebiederm.org
Acked-by: Marco Elver <elver@google.com>
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
---
 fs/signalfd.c          |  2 +-
 include/linux/signal.h |  2 +-
 kernel/signal.c        | 10 +++++-----
 3 files changed, 7 insertions(+), 7 deletions(-)

diff --git a/fs/signalfd.c b/fs/signalfd.c
index e87e59581653..83130244f653 100644
--- a/fs/signalfd.c
+++ b/fs/signalfd.c
@@ -132,7 +132,7 @@ static int signalfd_copyinfo(struct signalfd_siginfo __user *uinfo,
 		new.ssi_addr = (long) kinfo->si_addr;
 		new.ssi_addr_lsb = (short) kinfo->si_addr_lsb;
 		break;
-	case SIL_PERF_EVENT:
+	case SIL_FAULT_PERF_EVENT:
 		new.ssi_addr = (long) kinfo->si_addr;
 		new.ssi_perf = kinfo->si_perf;
 		break;
diff --git a/include/linux/signal.h b/include/linux/signal.h
index 5160fd45e5ca..ed896d790e46 100644
--- a/include/linux/signal.h
+++ b/include/linux/signal.h
@@ -44,7 +44,7 @@ enum siginfo_layout {
 	SIL_FAULT_MCEERR,
 	SIL_FAULT_BNDERR,
 	SIL_FAULT_PKUERR,
-	SIL_PERF_EVENT,
+	SIL_FAULT_PERF_EVENT,
 	SIL_CHLD,
 	SIL_RT,
 	SIL_SYS,
diff --git a/kernel/signal.c b/kernel/signal.c
index 7eaa8d84db4c..697c5fe58db8 100644
--- a/kernel/signal.c
+++ b/kernel/signal.c
@@ -1198,7 +1198,7 @@ static inline bool has_si_pid_and_uid(struct kernel_siginfo *info)
 	case SIL_FAULT_MCEERR:
 	case SIL_FAULT_BNDERR:
 	case SIL_FAULT_PKUERR:
-	case SIL_PERF_EVENT:
+	case SIL_FAULT_PERF_EVENT:
 	case SIL_SYS:
 		ret = false;
 		break;
@@ -2553,7 +2553,7 @@ static void hide_si_addr_tag_bits(struct ksignal *ksig)
 	case SIL_FAULT_MCEERR:
 	case SIL_FAULT_BNDERR:
 	case SIL_FAULT_PKUERR:
-	case SIL_PERF_EVENT:
+	case SIL_FAULT_PERF_EVENT:
 		ksig->info.si_addr = arch_untagged_si_addr(
 			ksig->info.si_addr, ksig->sig, ksig->info.si_code);
 		break;
@@ -3243,7 +3243,7 @@ enum siginfo_layout siginfo_layout(unsigned sig, int si_code)
 				layout = SIL_FAULT_PKUERR;
 #endif
 			else if ((sig == SIGTRAP) && (si_code == TRAP_PERF))
-				layout = SIL_PERF_EVENT;
+				layout = SIL_FAULT_PERF_EVENT;
 		}
 		else if (si_code <= NSIGPOLL)
 			layout = SIL_POLL;
@@ -3365,7 +3365,7 @@ void copy_siginfo_to_external32(struct compat_siginfo *to,
 		to->si_addr = ptr_to_compat(from->si_addr);
 		to->si_pkey = from->si_pkey;
 		break;
-	case SIL_PERF_EVENT:
+	case SIL_FAULT_PERF_EVENT:
 		to->si_addr = ptr_to_compat(from->si_addr);
 		to->si_perf = from->si_perf;
 		break;
@@ -3441,7 +3441,7 @@ static int post_copy_siginfo_from_user32(kernel_siginfo_t *to,
 		to->si_addr = compat_ptr(from->si_addr);
 		to->si_pkey = from->si_pkey;
 		break;
-	case SIL_PERF_EVENT:
+	case SIL_FAULT_PERF_EVENT:
 		to->si_addr = compat_ptr(from->si_addr);
 		to->si_perf = from->si_perf;
 		break;
-- 
2.30.1

Re: [PATCH v3 09/12] signal: Rename SIL_PERF_EVENT SIL_FAULT_PERF_EVENT for consistency

[Marco Elver]

On Wed, 5 May 2021 at 16:11, Eric W. Beiderman <ebiederm@xmission.com> wrote:
> From: "Eric W. Biederman" <ebiederm@xmission.com>
>
> It helps to know which part of the siginfo structure the siginfo_layout
> value is talking about.
>
> v1: https://lkml.kernel.org/r/m18s4zs7nu.fsf_-_@fess.ebiederm.org
> Acked-by: Marco Elver <elver@google.com>
> Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>

Reviewed-by: Marco Elver <elver@google.com>



> ---
>  fs/signalfd.c          |  2 +-
>  include/linux/signal.h |  2 +-
>  kernel/signal.c        | 10 +++++-----
>  3 files changed, 7 insertions(+), 7 deletions(-)
>
> diff --git a/fs/signalfd.c b/fs/signalfd.c
> index e87e59581653..83130244f653 100644
> --- a/fs/signalfd.c
> +++ b/fs/signalfd.c
> @@ -132,7 +132,7 @@ static int signalfd_copyinfo(struct signalfd_siginfo __user *uinfo,
>                 new.ssi_addr = (long) kinfo->si_addr;
>                 new.ssi_addr_lsb = (short) kinfo->si_addr_lsb;
>                 break;
> -       case SIL_PERF_EVENT:
> +       case SIL_FAULT_PERF_EVENT:
>                 new.ssi_addr = (long) kinfo->si_addr;
>                 new.ssi_perf = kinfo->si_perf;
>                 break;
> diff --git a/include/linux/signal.h b/include/linux/signal.h
> index 5160fd45e5ca..ed896d790e46 100644
> --- a/include/linux/signal.h
> +++ b/include/linux/signal.h
> @@ -44,7 +44,7 @@ enum siginfo_layout {
>         SIL_FAULT_MCEERR,
>         SIL_FAULT_BNDERR,
>         SIL_FAULT_PKUERR,
> -       SIL_PERF_EVENT,
> +       SIL_FAULT_PERF_EVENT,
>         SIL_CHLD,
>         SIL_RT,
>         SIL_SYS,
> diff --git a/kernel/signal.c b/kernel/signal.c
> index 7eaa8d84db4c..697c5fe58db8 100644
> --- a/kernel/signal.c
> +++ b/kernel/signal.c
> @@ -1198,7 +1198,7 @@ static inline bool has_si_pid_and_uid(struct kernel_siginfo *info)
>         case SIL_FAULT_MCEERR:
>         case SIL_FAULT_BNDERR:
>         case SIL_FAULT_PKUERR:
> -       case SIL_PERF_EVENT:
> +       case SIL_FAULT_PERF_EVENT:
>         case SIL_SYS:
>                 ret = false;
>                 break;
> @@ -2553,7 +2553,7 @@ static void hide_si_addr_tag_bits(struct ksignal *ksig)
>         case SIL_FAULT_MCEERR:
>         case SIL_FAULT_BNDERR:
>         case SIL_FAULT_PKUERR:
> -       case SIL_PERF_EVENT:
> +       case SIL_FAULT_PERF_EVENT:
>                 ksig->info.si_addr = arch_untagged_si_addr(
>                         ksig->info.si_addr, ksig->sig, ksig->info.si_code);
>                 break;
> @@ -3243,7 +3243,7 @@ enum siginfo_layout siginfo_layout(unsigned sig, int si_code)
>                                 layout = SIL_FAULT_PKUERR;
>  #endif
>                         else if ((sig == SIGTRAP) && (si_code == TRAP_PERF))
> -                               layout = SIL_PERF_EVENT;
> +                               layout = SIL_FAULT_PERF_EVENT;
>                 }
>                 else if (si_code <= NSIGPOLL)
>                         layout = SIL_POLL;
> @@ -3365,7 +3365,7 @@ void copy_siginfo_to_external32(struct compat_siginfo *to,
>                 to->si_addr = ptr_to_compat(from->si_addr);
>                 to->si_pkey = from->si_pkey;
>                 break;
> -       case SIL_PERF_EVENT:
> +       case SIL_FAULT_PERF_EVENT:
>                 to->si_addr = ptr_to_compat(from->si_addr);
>                 to->si_perf = from->si_perf;
>                 break;
> @@ -3441,7 +3441,7 @@ static int post_copy_siginfo_from_user32(kernel_siginfo_t *to,
>                 to->si_addr = compat_ptr(from->si_addr);
>                 to->si_pkey = from->si_pkey;
>                 break;
> -       case SIL_PERF_EVENT:
> +       case SIL_FAULT_PERF_EVENT:
>                 to->si_addr = compat_ptr(from->si_addr);
>                 to->si_perf = from->si_perf;
>                 break;
> --
> 2.30.1
>
> --
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[PATCH v3 10/12] signal: Factor force_sig_perf out of perf_sigtrap

[Eric W. Beiderman]

From: "Eric W. Biederman" <ebiederm@xmission.com>

Separate generating the signal from deciding it needs to be sent.

v1: https://lkml.kernel.org/r/m17dkjqqxz.fsf_-_@fess.ebiederm.org
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
---
 include/linux/sched/signal.h |  1 +
 kernel/events/core.c         | 11 ++---------
 kernel/signal.c              | 13 +++++++++++++
 3 files changed, 16 insertions(+), 9 deletions(-)

diff --git a/include/linux/sched/signal.h b/include/linux/sched/signal.h
index 7daa425f3055..1e2f61a1a512 100644
--- a/include/linux/sched/signal.h
+++ b/include/linux/sched/signal.h
@@ -318,6 +318,7 @@ int send_sig_mceerr(int code, void __user *, short, struct task_struct *);
 
 int force_sig_bnderr(void __user *addr, void __user *lower, void __user *upper);
 int force_sig_pkuerr(void __user *addr, u32 pkey);
+int force_sig_perf(void __user *addr, u32 type, u64 sig_data);
 
 int force_sig_fault_trapno(int sig, int code, void __user *addr, int trapno);
 int send_sig_fault_trapno(int sig, int code, void __user *addr, int trapno,
diff --git a/kernel/events/core.c b/kernel/events/core.c
index 928b166d888e..48ea8863183b 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -6394,8 +6394,6 @@ void perf_event_wakeup(struct perf_event *event)
 
 static void perf_sigtrap(struct perf_event *event)
 {
-	struct kernel_siginfo info;
-
 	/*
 	 * We'd expect this to only occur if the irq_work is delayed and either
 	 * ctx->task or current has changed in the meantime. This can be the
@@ -6410,13 +6408,8 @@ static void perf_sigtrap(struct perf_event *event)
 	if (current->flags & PF_EXITING)
 		return;
 
-	clear_siginfo(&info);
-	info.si_signo = SIGTRAP;
-	info.si_code = TRAP_PERF;
-	info.si_errno = event->attr.type;
-	info.si_perf = event->attr.sig_data;
-	info.si_addr = (void __user *)event->pending_addr;
-	force_sig_info(&info);
+	force_sig_perf((void __user *)event->pending_addr,
+		       event->attr.type, event->attr.sig_data);
 }
 
 static void perf_pending_event_disable(struct perf_event *event)
diff --git a/kernel/signal.c b/kernel/signal.c
index 697c5fe58db8..49560ceac048 100644
--- a/kernel/signal.c
+++ b/kernel/signal.c
@@ -1753,6 +1753,19 @@ int force_sig_pkuerr(void __user *addr, u32 pkey)
 }
 #endif
 
+int force_sig_perf(void __user *addr, u32 type, u64 sig_data)
+{
+	struct kernel_siginfo info;
+
+	clear_siginfo(&info);
+	info.si_signo = SIGTRAP;
+	info.si_errno = type;
+	info.si_code  = TRAP_PERF;
+	info.si_addr  = addr;
+	info.si_perf  = sig_data;
+	return force_sig_info(&info);
+}
+
 #if IS_ENABLED(CONFIG_SPARC)
 int force_sig_fault_trapno(int sig, int code, void __user *addr, int trapno)
 {
-- 
2.30.1

Re: [PATCH v3 10/12] signal: Factor force_sig_perf out of perf_sigtrap

[Marco Elver]

On Wed, 5 May 2021 at 16:11, Eric W. Beiderman <ebiederm@xmission.com> wrote:
> From: "Eric W. Biederman" <ebiederm@xmission.com>
>
> Separate generating the signal from deciding it needs to be sent.
>
> v1: https://lkml.kernel.org/r/m17dkjqqxz.fsf_-_@fess.ebiederm.org
> Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>

Reviewed-by: Marco Elver <elver@google.com>


> ---
>  include/linux/sched/signal.h |  1 +
>  kernel/events/core.c         | 11 ++---------
>  kernel/signal.c              | 13 +++++++++++++
>  3 files changed, 16 insertions(+), 9 deletions(-)
>
> diff --git a/include/linux/sched/signal.h b/include/linux/sched/signal.h
> index 7daa425f3055..1e2f61a1a512 100644
> --- a/include/linux/sched/signal.h
> +++ b/include/linux/sched/signal.h
> @@ -318,6 +318,7 @@ int send_sig_mceerr(int code, void __user *, short, struct task_struct *);
>
>  int force_sig_bnderr(void __user *addr, void __user *lower, void __user *upper);
>  int force_sig_pkuerr(void __user *addr, u32 pkey);
> +int force_sig_perf(void __user *addr, u32 type, u64 sig_data);
>
>  int force_sig_fault_trapno(int sig, int code, void __user *addr, int trapno);
>  int send_sig_fault_trapno(int sig, int code, void __user *addr, int trapno,
> diff --git a/kernel/events/core.c b/kernel/events/core.c
> index 928b166d888e..48ea8863183b 100644
> --- a/kernel/events/core.c
> +++ b/kernel/events/core.c
> @@ -6394,8 +6394,6 @@ void perf_event_wakeup(struct perf_event *event)
>
>  static void perf_sigtrap(struct perf_event *event)
>  {
> -       struct kernel_siginfo info;
> -
>         /*
>          * We'd expect this to only occur if the irq_work is delayed and either
>          * ctx->task or current has changed in the meantime. This can be the
> @@ -6410,13 +6408,8 @@ static void perf_sigtrap(struct perf_event *event)
>         if (current->flags & PF_EXITING)
>                 return;
>
> -       clear_siginfo(&info);
> -       info.si_signo = SIGTRAP;
> -       info.si_code = TRAP_PERF;
> -       info.si_errno = event->attr.type;
> -       info.si_perf = event->attr.sig_data;
> -       info.si_addr = (void __user *)event->pending_addr;
> -       force_sig_info(&info);
> +       force_sig_perf((void __user *)event->pending_addr,
> +                      event->attr.type, event->attr.sig_data);
>  }
>
>  static void perf_pending_event_disable(struct perf_event *event)
> diff --git a/kernel/signal.c b/kernel/signal.c
> index 697c5fe58db8..49560ceac048 100644
> --- a/kernel/signal.c
> +++ b/kernel/signal.c
> @@ -1753,6 +1753,19 @@ int force_sig_pkuerr(void __user *addr, u32 pkey)
>  }
>  #endif
>
> +int force_sig_perf(void __user *addr, u32 type, u64 sig_data)
> +{
> +       struct kernel_siginfo info;
> +
> +       clear_siginfo(&info);
> +       info.si_signo = SIGTRAP;
> +       info.si_errno = type;
> +       info.si_code  = TRAP_PERF;
> +       info.si_addr  = addr;
> +       info.si_perf  = sig_data;
> +       return force_sig_info(&info);
> +}
> +
>  #if IS_ENABLED(CONFIG_SPARC)
>  int force_sig_fault_trapno(int sig, int code, void __user *addr, int trapno)
>  {
> --
> 2.30.1
>

Re: [PATCH v3 10/12] signal: Factor force_sig_perf out of perf_sigtrap

[Peter Zijlstra]

On Wed, May 05, 2021 at 09:10:59AM -0500, Eric W. Beiderman wrote:
> From: "Eric W. Biederman" <ebiederm@xmission.com>
> 
> Separate generating the signal from deciding it needs to be sent.
> 
> v1: https://lkml.kernel.org/r/m17dkjqqxz.fsf_-_@fess.ebiederm.org
> Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>

Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>

Thanks for cleaning all that up.

[PATCH v3 11/12] signal: Deliver all of the siginfo perf data in _perf

[Eric W. Beiderman]

From: "Eric W. Biederman" <ebiederm@xmission.com>

Don't abuse si_errno and deliver all of the perf data in _perf member
of siginfo_t.

The data field in the perf data structures in a u64 to allow a pointer
to be encoded without needed to implement a 32bit and 64bit version of
the same structure.  There already exists a 32bit and 64bit versions
siginfo_t, and the 32bit version can not include a 64bit member as it
only has 32bit alignment.  So unsigned long is used in siginfo_t
instead of a u64 as unsigned long can encode a pointer on all
architectures linux supports.

v1: https://lkml.kernel.org/r/m11rarqqx2.fsf_-_@fess.ebiederm.org
v2: https://lkml.kernel.org/r/20210503203814.25487-10-ebiederm@xmission.com
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
---
 arch/arm/kernel/signal.c                      |  3 ++-
 arch/arm64/kernel/signal.c                    |  3 ++-
 arch/arm64/kernel/signal32.c                  |  3 ++-
 arch/sparc/kernel/signal32.c                  |  3 ++-
 arch/sparc/kernel/signal_64.c                 |  3 ++-
 arch/x86/kernel/signal_compat.c               |  6 ++++--
 fs/signalfd.c                                 |  3 ++-
 include/linux/compat.h                        |  5 ++++-
 include/uapi/asm-generic/siginfo.h            |  8 +++++--
 include/uapi/linux/signalfd.h                 |  4 ++--
 kernel/signal.c                               | 21 ++++++++++++-------
 .../selftests/perf_events/sigtrap_threads.c   | 12 +++++------
 12 files changed, 47 insertions(+), 27 deletions(-)

diff --git a/arch/arm/kernel/signal.c b/arch/arm/kernel/signal.c
index 643bcb0f091b..f3800c0f428b 100644
--- a/arch/arm/kernel/signal.c
+++ b/arch/arm/kernel/signal.c
@@ -757,7 +757,8 @@ static_assert(offsetof(siginfo_t, si_addr_lsb)	== 0x10);
 static_assert(offsetof(siginfo_t, si_lower)	== 0x14);
 static_assert(offsetof(siginfo_t, si_upper)	== 0x18);
 static_assert(offsetof(siginfo_t, si_pkey)	== 0x14);
-static_assert(offsetof(siginfo_t, si_perf)	== 0x10);
+static_assert(offsetof(siginfo_t, si_perf_data)	== 0x10);
+static_assert(offsetof(siginfo_t, si_perf_type)	== 0x14);
 static_assert(offsetof(siginfo_t, si_band)	== 0x0c);
 static_assert(offsetof(siginfo_t, si_fd)	== 0x10);
 static_assert(offsetof(siginfo_t, si_call_addr)	== 0x0c);
diff --git a/arch/arm64/kernel/signal.c b/arch/arm64/kernel/signal.c
index ad4bd27fc044..b3978b468bd4 100644
--- a/arch/arm64/kernel/signal.c
+++ b/arch/arm64/kernel/signal.c
@@ -1005,7 +1005,8 @@ static_assert(offsetof(siginfo_t, si_addr_lsb)	== 0x18);
 static_assert(offsetof(siginfo_t, si_lower)	== 0x20);
 static_assert(offsetof(siginfo_t, si_upper)	== 0x28);
 static_assert(offsetof(siginfo_t, si_pkey)	== 0x20);
-static_assert(offsetof(siginfo_t, si_perf)	== 0x18);
+static_assert(offsetof(siginfo_t, si_perf_data)	== 0x18);
+static_assert(offsetof(siginfo_t, si_perf_type)	== 0x20);
 static_assert(offsetof(siginfo_t, si_band)	== 0x10);
 static_assert(offsetof(siginfo_t, si_fd)	== 0x18);
 static_assert(offsetof(siginfo_t, si_call_addr)	== 0x10);
diff --git a/arch/arm64/kernel/signal32.c b/arch/arm64/kernel/signal32.c
index ee6c7484e130..d3be01c46bec 100644
--- a/arch/arm64/kernel/signal32.c
+++ b/arch/arm64/kernel/signal32.c
@@ -489,7 +489,8 @@ static_assert(offsetof(compat_siginfo_t, si_addr_lsb)	== 0x10);
 static_assert(offsetof(compat_siginfo_t, si_lower)	== 0x14);
 static_assert(offsetof(compat_siginfo_t, si_upper)	== 0x18);
 static_assert(offsetof(compat_siginfo_t, si_pkey)	== 0x14);
-static_assert(offsetof(compat_siginfo_t, si_perf)	== 0x10);
+static_assert(offsetof(compat_siginfo_t, si_perf_data)	== 0x10);
+static_assert(offsetof(compat_siginfo_t, si_perf_type)	== 0x14);
 static_assert(offsetof(compat_siginfo_t, si_band)	== 0x0c);
 static_assert(offsetof(compat_siginfo_t, si_fd)		== 0x10);
 static_assert(offsetof(compat_siginfo_t, si_call_addr)	== 0x0c);
diff --git a/arch/sparc/kernel/signal32.c b/arch/sparc/kernel/signal32.c
index 5573722e34ad..4276b9e003ca 100644
--- a/arch/sparc/kernel/signal32.c
+++ b/arch/sparc/kernel/signal32.c
@@ -778,6 +778,7 @@ static_assert(offsetof(compat_siginfo_t, si_addr_lsb)	== 0x10);
 static_assert(offsetof(compat_siginfo_t, si_lower)	== 0x14);
 static_assert(offsetof(compat_siginfo_t, si_upper)	== 0x18);
 static_assert(offsetof(compat_siginfo_t, si_pkey)	== 0x14);
-static_assert(offsetof(compat_siginfo_t, si_perf)	== 0x10);
+static_assert(offsetof(compat_siginfo_t, si_perf_data)	== 0x10);
+static_assert(offsetof(compat_siginfo_t, si_perf_type)	== 0x14);
 static_assert(offsetof(compat_siginfo_t, si_band)	== 0x0c);
 static_assert(offsetof(compat_siginfo_t, si_fd)		== 0x10);
diff --git a/arch/sparc/kernel/signal_64.c b/arch/sparc/kernel/signal_64.c
index a69a78984c36..cea23cf95600 100644
--- a/arch/sparc/kernel/signal_64.c
+++ b/arch/sparc/kernel/signal_64.c
@@ -588,6 +588,7 @@ static_assert(offsetof(siginfo_t, si_addr_lsb)	== 0x18);
 static_assert(offsetof(siginfo_t, si_lower)	== 0x20);
 static_assert(offsetof(siginfo_t, si_upper)	== 0x28);
 static_assert(offsetof(siginfo_t, si_pkey)	== 0x20);
-static_assert(offsetof(siginfo_t, si_perf)	== 0x18);
+static_assert(offsetof(siginfo_t, si_perf_data)	== 0x18);
+static_assert(offsetof(siginfo_t, si_perf_type)	== 0x20);
 static_assert(offsetof(siginfo_t, si_band)	== 0x10);
 static_assert(offsetof(siginfo_t, si_fd)	== 0x14);
diff --git a/arch/x86/kernel/signal_compat.c b/arch/x86/kernel/signal_compat.c
index c9601f092a1e..b52407c56000 100644
--- a/arch/x86/kernel/signal_compat.c
+++ b/arch/x86/kernel/signal_compat.c
@@ -147,8 +147,10 @@ static inline void signal_compat_build_tests(void)
 	BUILD_BUG_ON(offsetof(siginfo_t, si_pkey) != 0x20);
 	BUILD_BUG_ON(offsetof(compat_siginfo_t, si_pkey) != 0x14);
 
-	BUILD_BUG_ON(offsetof(siginfo_t, si_perf) != 0x18);
-	BUILD_BUG_ON(offsetof(compat_siginfo_t, si_perf) != 0x10);
+	BUILD_BUG_ON(offsetof(siginfo_t, si_perf_data) != 0x18);
+	BUILD_BUG_ON(offsetof(siginfo_t, si_perf_type) != 0x20);
+	BUILD_BUG_ON(offsetof(compat_siginfo_t, si_perf_data) != 0x10);
+	BUILD_BUG_ON(offsetof(compat_siginfo_t, si_perf_type) != 0x14);
 
 	CHECK_CSI_OFFSET(_sigpoll);
 	CHECK_CSI_SIZE  (_sigpoll, 2*sizeof(int));
diff --git a/fs/signalfd.c b/fs/signalfd.c
index 83130244f653..335ad39f3900 100644
--- a/fs/signalfd.c
+++ b/fs/signalfd.c
@@ -134,7 +134,8 @@ static int signalfd_copyinfo(struct signalfd_siginfo __user *uinfo,
 		break;
 	case SIL_FAULT_PERF_EVENT:
 		new.ssi_addr = (long) kinfo->si_addr;
-		new.ssi_perf = kinfo->si_perf;
+		new.ssi_perf_type = kinfo->si_perf_type;
+		new.ssi_perf_data = kinfo->si_perf_data;
 		break;
 	case SIL_CHLD:
 		new.ssi_pid    = kinfo->si_pid;
diff --git a/include/linux/compat.h b/include/linux/compat.h
index 6af7bef15e94..a27fffaae121 100644
--- a/include/linux/compat.h
+++ b/include/linux/compat.h
@@ -236,7 +236,10 @@ typedef struct compat_siginfo {
 					u32 _pkey;
 				} _addr_pkey;
 				/* used when si_code=TRAP_PERF */
-				compat_ulong_t _perf;
+				struct {
+					compat_ulong_t _data;
+					u32 _type;
+				} _perf;
 			};
 		} _sigfault;
 
diff --git a/include/uapi/asm-generic/siginfo.h b/include/uapi/asm-generic/siginfo.h
index 3503282021aa..3ba180f550d7 100644
--- a/include/uapi/asm-generic/siginfo.h
+++ b/include/uapi/asm-generic/siginfo.h
@@ -96,7 +96,10 @@ union __sifields {
 				__u32 _pkey;
 			} _addr_pkey;
 			/* used when si_code=TRAP_PERF */
-			unsigned long _perf;
+			struct {
+				unsigned long _data;
+				__u32 _type;
+			} _perf;
 		};
 	} _sigfault;
 
@@ -159,7 +162,8 @@ typedef struct siginfo {
 #define si_lower	_sifields._sigfault._addr_bnd._lower
 #define si_upper	_sifields._sigfault._addr_bnd._upper
 #define si_pkey		_sifields._sigfault._addr_pkey._pkey
-#define si_perf		_sifields._sigfault._perf
+#define si_perf_data	_sifields._sigfault._perf._data
+#define si_perf_type	_sifields._sigfault._perf._type
 #define si_band		_sifields._sigpoll._band
 #define si_fd		_sifields._sigpoll._fd
 #define si_call_addr	_sifields._sigsys._call_addr
diff --git a/include/uapi/linux/signalfd.h b/include/uapi/linux/signalfd.h
index 7e333042c7e3..e78dddf433fc 100644
--- a/include/uapi/linux/signalfd.h
+++ b/include/uapi/linux/signalfd.h
@@ -39,8 +39,8 @@ struct signalfd_siginfo {
 	__s32 ssi_syscall;
 	__u64 ssi_call_addr;
 	__u32 ssi_arch;
-	__u32 __pad3;
-	__u64 ssi_perf;
+	__u32 ssi_perf_type;
+	__u64 ssi_perf_data;
 
 	/*
 	 * Pad strcture to 128 bytes. Remember to update the
diff --git a/kernel/signal.c b/kernel/signal.c
index 49560ceac048..7fec9d1c5b11 100644
--- a/kernel/signal.c
+++ b/kernel/signal.c
@@ -1758,11 +1758,13 @@ int force_sig_perf(void __user *addr, u32 type, u64 sig_data)
 	struct kernel_siginfo info;
 
 	clear_siginfo(&info);
-	info.si_signo = SIGTRAP;
-	info.si_errno = type;
-	info.si_code  = TRAP_PERF;
-	info.si_addr  = addr;
-	info.si_perf  = sig_data;
+	info.si_signo     = SIGTRAP;
+	info.si_errno     = 0;
+	info.si_code      = TRAP_PERF;
+	info.si_addr      = addr;
+	info.si_perf_data = sig_data;
+	info.si_perf_type = type;
+
 	return force_sig_info(&info);
 }
 
@@ -3380,7 +3382,8 @@ void copy_siginfo_to_external32(struct compat_siginfo *to,
 		break;
 	case SIL_FAULT_PERF_EVENT:
 		to->si_addr = ptr_to_compat(from->si_addr);
-		to->si_perf = from->si_perf;
+		to->si_perf_data = from->si_perf_data;
+		to->si_perf_type = from->si_perf_type;
 		break;
 	case SIL_CHLD:
 		to->si_pid = from->si_pid;
@@ -3456,7 +3459,8 @@ static int post_copy_siginfo_from_user32(kernel_siginfo_t *to,
 		break;
 	case SIL_FAULT_PERF_EVENT:
 		to->si_addr = compat_ptr(from->si_addr);
-		to->si_perf = from->si_perf;
+		to->si_perf_data = from->si_perf_data;
+		to->si_perf_type = from->si_perf_type;
 		break;
 	case SIL_CHLD:
 		to->si_pid    = from->si_pid;
@@ -4639,7 +4643,8 @@ static inline void siginfo_buildtime_checks(void)
 	CHECK_OFFSET(si_lower);
 	CHECK_OFFSET(si_upper);
 	CHECK_OFFSET(si_pkey);
-	CHECK_OFFSET(si_perf);
+	CHECK_OFFSET(si_perf_data);
+	CHECK_OFFSET(si_perf_type);
 
 	/* sigpoll */
 	CHECK_OFFSET(si_band);
diff --git a/tools/testing/selftests/perf_events/sigtrap_threads.c b/tools/testing/selftests/perf_events/sigtrap_threads.c
index 78ddf5e11625..fde123066a8c 100644
--- a/tools/testing/selftests/perf_events/sigtrap_threads.c
+++ b/tools/testing/selftests/perf_events/sigtrap_threads.c
@@ -164,8 +164,8 @@ TEST_F(sigtrap_threads, enable_event)
 	EXPECT_EQ(ctx.signal_count, NUM_THREADS);
 	EXPECT_EQ(ctx.tids_want_signal, 0);
 	EXPECT_EQ(ctx.first_siginfo.si_addr, &ctx.iterate_on);
-	EXPECT_EQ(ctx.first_siginfo.si_errno, PERF_TYPE_BREAKPOINT);
-	EXPECT_EQ(ctx.first_siginfo.si_perf, TEST_SIG_DATA(&ctx.iterate_on));
+	EXPECT_EQ(ctx.first_siginfo.si_perf_type, PERF_TYPE_BREAKPOINT);
+	EXPECT_EQ(ctx.first_siginfo.si_perf_data, TEST_SIG_DATA(&ctx.iterate_on));
 
 	/* Check enabled for parent. */
 	ctx.iterate_on = 0;
@@ -183,8 +183,8 @@ TEST_F(sigtrap_threads, modify_and_enable_event)
 	EXPECT_EQ(ctx.signal_count, NUM_THREADS);
 	EXPECT_EQ(ctx.tids_want_signal, 0);
 	EXPECT_EQ(ctx.first_siginfo.si_addr, &ctx.iterate_on);
-	EXPECT_EQ(ctx.first_siginfo.si_errno, PERF_TYPE_BREAKPOINT);
-	EXPECT_EQ(ctx.first_siginfo.si_perf, TEST_SIG_DATA(&ctx.iterate_on));
+	EXPECT_EQ(ctx.first_siginfo.si_perf_type, PERF_TYPE_BREAKPOINT);
+	EXPECT_EQ(ctx.first_siginfo.si_perf_data, TEST_SIG_DATA(&ctx.iterate_on));
 
 	/* Check enabled for parent. */
 	ctx.iterate_on = 0;
@@ -203,8 +203,8 @@ TEST_F(sigtrap_threads, signal_stress)
 	EXPECT_EQ(ctx.signal_count, NUM_THREADS * ctx.iterate_on);
 	EXPECT_EQ(ctx.tids_want_signal, 0);
 	EXPECT_EQ(ctx.first_siginfo.si_addr, &ctx.iterate_on);
-	EXPECT_EQ(ctx.first_siginfo.si_errno, PERF_TYPE_BREAKPOINT);
-	EXPECT_EQ(ctx.first_siginfo.si_perf, TEST_SIG_DATA(&ctx.iterate_on));
+	EXPECT_EQ(ctx.first_siginfo.si_perf_type, PERF_TYPE_BREAKPOINT);
+	EXPECT_EQ(ctx.first_siginfo.si_perf_data, TEST_SIG_DATA(&ctx.iterate_on));
 }
 
 TEST_HARNESS_MAIN
-- 
2.30.1

Re: [PATCH v3 11/12] signal: Deliver all of the siginfo perf data in _perf

[Marco Elver]

On Wed, 5 May 2021 at 16:11, Eric W. Beiderman <ebiederm@xmission.com> wrote:
> From: "Eric W. Biederman" <ebiederm@xmission.com>
>
> Don't abuse si_errno and deliver all of the perf data in _perf member
> of siginfo_t.
>
> The data field in the perf data structures in a u64 to allow a pointer
> to be encoded without needed to implement a 32bit and 64bit version of
> the same structure.  There already exists a 32bit and 64bit versions
> siginfo_t, and the 32bit version can not include a 64bit member as it
> only has 32bit alignment.  So unsigned long is used in siginfo_t
> instead of a u64 as unsigned long can encode a pointer on all
> architectures linux supports.

Since there is no functional change (we already had the unsigned long
here), the explanation made me think there was a change in that area
(but there wasn't). (Can leave as-is, but a "Note: " or similar if you
deem it appropriate.)

> v1: https://lkml.kernel.org/r/m11rarqqx2.fsf_-_@fess.ebiederm.org
> v2: https://lkml.kernel.org/r/20210503203814.25487-10-ebiederm@xmission.com
> Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>

Reviewed-by: Marco Elver <elver@google.com>

Thank you!


> ---
>  arch/arm/kernel/signal.c                      |  3 ++-
>  arch/arm64/kernel/signal.c                    |  3 ++-
>  arch/arm64/kernel/signal32.c                  |  3 ++-
>  arch/sparc/kernel/signal32.c                  |  3 ++-
>  arch/sparc/kernel/signal_64.c                 |  3 ++-
>  arch/x86/kernel/signal_compat.c               |  6 ++++--
>  fs/signalfd.c                                 |  3 ++-
>  include/linux/compat.h                        |  5 ++++-
>  include/uapi/asm-generic/siginfo.h            |  8 +++++--
>  include/uapi/linux/signalfd.h                 |  4 ++--
>  kernel/signal.c                               | 21 ++++++++++++-------
>  .../selftests/perf_events/sigtrap_threads.c   | 12 +++++------
>  12 files changed, 47 insertions(+), 27 deletions(-)
>
> diff --git a/arch/arm/kernel/signal.c b/arch/arm/kernel/signal.c
> index 643bcb0f091b..f3800c0f428b 100644
> --- a/arch/arm/kernel/signal.c
> +++ b/arch/arm/kernel/signal.c
> @@ -757,7 +757,8 @@ static_assert(offsetof(siginfo_t, si_addr_lsb)      == 0x10);
>  static_assert(offsetof(siginfo_t, si_lower)    == 0x14);
>  static_assert(offsetof(siginfo_t, si_upper)    == 0x18);
>  static_assert(offsetof(siginfo_t, si_pkey)     == 0x14);
> -static_assert(offsetof(siginfo_t, si_perf)     == 0x10);
> +static_assert(offsetof(siginfo_t, si_perf_data)        == 0x10);
> +static_assert(offsetof(siginfo_t, si_perf_type)        == 0x14);
>  static_assert(offsetof(siginfo_t, si_band)     == 0x0c);
>  static_assert(offsetof(siginfo_t, si_fd)       == 0x10);
>  static_assert(offsetof(siginfo_t, si_call_addr)        == 0x0c);
> diff --git a/arch/arm64/kernel/signal.c b/arch/arm64/kernel/signal.c
> index ad4bd27fc044..b3978b468bd4 100644
> --- a/arch/arm64/kernel/signal.c
> +++ b/arch/arm64/kernel/signal.c
> @@ -1005,7 +1005,8 @@ static_assert(offsetof(siginfo_t, si_addr_lsb)    == 0x18);
>  static_assert(offsetof(siginfo_t, si_lower)    == 0x20);
>  static_assert(offsetof(siginfo_t, si_upper)    == 0x28);
>  static_assert(offsetof(siginfo_t, si_pkey)     == 0x20);
> -static_assert(offsetof(siginfo_t, si_perf)     == 0x18);
> +static_assert(offsetof(siginfo_t, si_perf_data)        == 0x18);
> +static_assert(offsetof(siginfo_t, si_perf_type)        == 0x20);
>  static_assert(offsetof(siginfo_t, si_band)     == 0x10);
>  static_assert(offsetof(siginfo_t, si_fd)       == 0x18);
>  static_assert(offsetof(siginfo_t, si_call_addr)        == 0x10);
> diff --git a/arch/arm64/kernel/signal32.c b/arch/arm64/kernel/signal32.c
> index ee6c7484e130..d3be01c46bec 100644
> --- a/arch/arm64/kernel/signal32.c
> +++ b/arch/arm64/kernel/signal32.c
> @@ -489,7 +489,8 @@ static_assert(offsetof(compat_siginfo_t, si_addr_lsb)       == 0x10);
>  static_assert(offsetof(compat_siginfo_t, si_lower)     == 0x14);
>  static_assert(offsetof(compat_siginfo_t, si_upper)     == 0x18);
>  static_assert(offsetof(compat_siginfo_t, si_pkey)      == 0x14);
> -static_assert(offsetof(compat_siginfo_t, si_perf)      == 0x10);
> +static_assert(offsetof(compat_siginfo_t, si_perf_data) == 0x10);
> +static_assert(offsetof(compat_siginfo_t, si_perf_type) == 0x14);
>  static_assert(offsetof(compat_siginfo_t, si_band)      == 0x0c);
>  static_assert(offsetof(compat_siginfo_t, si_fd)                == 0x10);
>  static_assert(offsetof(compat_siginfo_t, si_call_addr) == 0x0c);
> diff --git a/arch/sparc/kernel/signal32.c b/arch/sparc/kernel/signal32.c
> index 5573722e34ad..4276b9e003ca 100644
> --- a/arch/sparc/kernel/signal32.c
> +++ b/arch/sparc/kernel/signal32.c
> @@ -778,6 +778,7 @@ static_assert(offsetof(compat_siginfo_t, si_addr_lsb)       == 0x10);
>  static_assert(offsetof(compat_siginfo_t, si_lower)     == 0x14);
>  static_assert(offsetof(compat_siginfo_t, si_upper)     == 0x18);
>  static_assert(offsetof(compat_siginfo_t, si_pkey)      == 0x14);
> -static_assert(offsetof(compat_siginfo_t, si_perf)      == 0x10);
> +static_assert(offsetof(compat_siginfo_t, si_perf_data) == 0x10);
> +static_assert(offsetof(compat_siginfo_t, si_perf_type) == 0x14);
>  static_assert(offsetof(compat_siginfo_t, si_band)      == 0x0c);
>  static_assert(offsetof(compat_siginfo_t, si_fd)                == 0x10);
> diff --git a/arch/sparc/kernel/signal_64.c b/arch/sparc/kernel/signal_64.c
> index a69a78984c36..cea23cf95600 100644
> --- a/arch/sparc/kernel/signal_64.c
> +++ b/arch/sparc/kernel/signal_64.c
> @@ -588,6 +588,7 @@ static_assert(offsetof(siginfo_t, si_addr_lsb)      == 0x18);
>  static_assert(offsetof(siginfo_t, si_lower)    == 0x20);
>  static_assert(offsetof(siginfo_t, si_upper)    == 0x28);
>  static_assert(offsetof(siginfo_t, si_pkey)     == 0x20);
> -static_assert(offsetof(siginfo_t, si_perf)     == 0x18);
> +static_assert(offsetof(siginfo_t, si_perf_data)        == 0x18);
> +static_assert(offsetof(siginfo_t, si_perf_type)        == 0x20);
>  static_assert(offsetof(siginfo_t, si_band)     == 0x10);
>  static_assert(offsetof(siginfo_t, si_fd)       == 0x14);
> diff --git a/arch/x86/kernel/signal_compat.c b/arch/x86/kernel/signal_compat.c
> index c9601f092a1e..b52407c56000 100644
> --- a/arch/x86/kernel/signal_compat.c
> +++ b/arch/x86/kernel/signal_compat.c
> @@ -147,8 +147,10 @@ static inline void signal_compat_build_tests(void)
>         BUILD_BUG_ON(offsetof(siginfo_t, si_pkey) != 0x20);
>         BUILD_BUG_ON(offsetof(compat_siginfo_t, si_pkey) != 0x14);
>
> -       BUILD_BUG_ON(offsetof(siginfo_t, si_perf) != 0x18);
> -       BUILD_BUG_ON(offsetof(compat_siginfo_t, si_perf) != 0x10);
> +       BUILD_BUG_ON(offsetof(siginfo_t, si_perf_data) != 0x18);
> +       BUILD_BUG_ON(offsetof(siginfo_t, si_perf_type) != 0x20);
> +       BUILD_BUG_ON(offsetof(compat_siginfo_t, si_perf_data) != 0x10);
> +       BUILD_BUG_ON(offsetof(compat_siginfo_t, si_perf_type) != 0x14);
>
>         CHECK_CSI_OFFSET(_sigpoll);
>         CHECK_CSI_SIZE  (_sigpoll, 2*sizeof(int));
> diff --git a/fs/signalfd.c b/fs/signalfd.c
> index 83130244f653..335ad39f3900 100644
> --- a/fs/signalfd.c
> +++ b/fs/signalfd.c
> @@ -134,7 +134,8 @@ static int signalfd_copyinfo(struct signalfd_siginfo __user *uinfo,
>                 break;
>         case SIL_FAULT_PERF_EVENT:
>                 new.ssi_addr = (long) kinfo->si_addr;
> -               new.ssi_perf = kinfo->si_perf;
> +               new.ssi_perf_type = kinfo->si_perf_type;
> +               new.ssi_perf_data = kinfo->si_perf_data;
>                 break;
>         case SIL_CHLD:
>                 new.ssi_pid    = kinfo->si_pid;
> diff --git a/include/linux/compat.h b/include/linux/compat.h
> index 6af7bef15e94..a27fffaae121 100644
> --- a/include/linux/compat.h
> +++ b/include/linux/compat.h
> @@ -236,7 +236,10 @@ typedef struct compat_siginfo {
>                                         u32 _pkey;
>                                 } _addr_pkey;
>                                 /* used when si_code=TRAP_PERF */
> -                               compat_ulong_t _perf;
> +                               struct {
> +                                       compat_ulong_t _data;
> +                                       u32 _type;
> +                               } _perf;
>                         };
>                 } _sigfault;
>
> diff --git a/include/uapi/asm-generic/siginfo.h b/include/uapi/asm-generic/siginfo.h
> index 3503282021aa..3ba180f550d7 100644
> --- a/include/uapi/asm-generic/siginfo.h
> +++ b/include/uapi/asm-generic/siginfo.h
> @@ -96,7 +96,10 @@ union __sifields {
>                                 __u32 _pkey;
>                         } _addr_pkey;
>                         /* used when si_code=TRAP_PERF */
> -                       unsigned long _perf;
> +                       struct {
> +                               unsigned long _data;
> +                               __u32 _type;
> +                       } _perf;
>                 };
>         } _sigfault;
>
> @@ -159,7 +162,8 @@ typedef struct siginfo {
>  #define si_lower       _sifields._sigfault._addr_bnd._lower
>  #define si_upper       _sifields._sigfault._addr_bnd._upper
>  #define si_pkey                _sifields._sigfault._addr_pkey._pkey
> -#define si_perf                _sifields._sigfault._perf
> +#define si_perf_data   _sifields._sigfault._perf._data
> +#define si_perf_type   _sifields._sigfault._perf._type
>  #define si_band                _sifields._sigpoll._band
>  #define si_fd          _sifields._sigpoll._fd
>  #define si_call_addr   _sifields._sigsys._call_addr
> diff --git a/include/uapi/linux/signalfd.h b/include/uapi/linux/signalfd.h
> index 7e333042c7e3..e78dddf433fc 100644
> --- a/include/uapi/linux/signalfd.h
> +++ b/include/uapi/linux/signalfd.h
> @@ -39,8 +39,8 @@ struct signalfd_siginfo {
>         __s32 ssi_syscall;
>         __u64 ssi_call_addr;
>         __u32 ssi_arch;
> -       __u32 __pad3;
> -       __u64 ssi_perf;
> +       __u32 ssi_perf_type;
> +       __u64 ssi_perf_data;
>
>         /*
>          * Pad strcture to 128 bytes. Remember to update the
> diff --git a/kernel/signal.c b/kernel/signal.c
> index 49560ceac048..7fec9d1c5b11 100644
> --- a/kernel/signal.c
> +++ b/kernel/signal.c
> @@ -1758,11 +1758,13 @@ int force_sig_perf(void __user *addr, u32 type, u64 sig_data)
>         struct kernel_siginfo info;
>
>         clear_siginfo(&info);
> -       info.si_signo = SIGTRAP;
> -       info.si_errno = type;
> -       info.si_code  = TRAP_PERF;
> -       info.si_addr  = addr;
> -       info.si_perf  = sig_data;
> +       info.si_signo     = SIGTRAP;
> +       info.si_errno     = 0;
> +       info.si_code      = TRAP_PERF;
> +       info.si_addr      = addr;
> +       info.si_perf_data = sig_data;
> +       info.si_perf_type = type;
> +
>         return force_sig_info(&info);
>  }
>
> @@ -3380,7 +3382,8 @@ void copy_siginfo_to_external32(struct compat_siginfo *to,
>                 break;
>         case SIL_FAULT_PERF_EVENT:
>                 to->si_addr = ptr_to_compat(from->si_addr);
> -               to->si_perf = from->si_perf;
> +               to->si_perf_data = from->si_perf_data;
> +               to->si_perf_type = from->si_perf_type;
>                 break;
>         case SIL_CHLD:
>                 to->si_pid = from->si_pid;
> @@ -3456,7 +3459,8 @@ static int post_copy_siginfo_from_user32(kernel_siginfo_t *to,
>                 break;
>         case SIL_FAULT_PERF_EVENT:
>                 to->si_addr = compat_ptr(from->si_addr);
> -               to->si_perf = from->si_perf;
> +               to->si_perf_data = from->si_perf_data;
> +               to->si_perf_type = from->si_perf_type;
>                 break;
>         case SIL_CHLD:
>                 to->si_pid    = from->si_pid;
> @@ -4639,7 +4643,8 @@ static inline void siginfo_buildtime_checks(void)
>         CHECK_OFFSET(si_lower);
>         CHECK_OFFSET(si_upper);
>         CHECK_OFFSET(si_pkey);
> -       CHECK_OFFSET(si_perf);
> +       CHECK_OFFSET(si_perf_data);
> +       CHECK_OFFSET(si_perf_type);
>
>         /* sigpoll */
>         CHECK_OFFSET(si_band);
> diff --git a/tools/testing/selftests/perf_events/sigtrap_threads.c b/tools/testing/selftests/perf_events/sigtrap_threads.c
> index 78ddf5e11625..fde123066a8c 100644
> --- a/tools/testing/selftests/perf_events/sigtrap_threads.c
> +++ b/tools/testing/selftests/perf_events/sigtrap_threads.c
> @@ -164,8 +164,8 @@ TEST_F(sigtrap_threads, enable_event)
>         EXPECT_EQ(ctx.signal_count, NUM_THREADS);
>         EXPECT_EQ(ctx.tids_want_signal, 0);
>         EXPECT_EQ(ctx.first_siginfo.si_addr, &ctx.iterate_on);
> -       EXPECT_EQ(ctx.first_siginfo.si_errno, PERF_TYPE_BREAKPOINT);
> -       EXPECT_EQ(ctx.first_siginfo.si_perf, TEST_SIG_DATA(&ctx.iterate_on));
> +       EXPECT_EQ(ctx.first_siginfo.si_perf_type, PERF_TYPE_BREAKPOINT);
> +       EXPECT_EQ(ctx.first_siginfo.si_perf_data, TEST_SIG_DATA(&ctx.iterate_on));
>
>         /* Check enabled for parent. */
>         ctx.iterate_on = 0;
> @@ -183,8 +183,8 @@ TEST_F(sigtrap_threads, modify_and_enable_event)
>         EXPECT_EQ(ctx.signal_count, NUM_THREADS);
>         EXPECT_EQ(ctx.tids_want_signal, 0);
>         EXPECT_EQ(ctx.first_siginfo.si_addr, &ctx.iterate_on);
> -       EXPECT_EQ(ctx.first_siginfo.si_errno, PERF_TYPE_BREAKPOINT);
> -       EXPECT_EQ(ctx.first_siginfo.si_perf, TEST_SIG_DATA(&ctx.iterate_on));
> +       EXPECT_EQ(ctx.first_siginfo.si_perf_type, PERF_TYPE_BREAKPOINT);
> +       EXPECT_EQ(ctx.first_siginfo.si_perf_data, TEST_SIG_DATA(&ctx.iterate_on));
>
>         /* Check enabled for parent. */
>         ctx.iterate_on = 0;
> @@ -203,8 +203,8 @@ TEST_F(sigtrap_threads, signal_stress)
>         EXPECT_EQ(ctx.signal_count, NUM_THREADS * ctx.iterate_on);
>         EXPECT_EQ(ctx.tids_want_signal, 0);
>         EXPECT_EQ(ctx.first_siginfo.si_addr, &ctx.iterate_on);
> -       EXPECT_EQ(ctx.first_siginfo.si_errno, PERF_TYPE_BREAKPOINT);
> -       EXPECT_EQ(ctx.first_siginfo.si_perf, TEST_SIG_DATA(&ctx.iterate_on));
> +       EXPECT_EQ(ctx.first_siginfo.si_perf_type, PERF_TYPE_BREAKPOINT);
> +       EXPECT_EQ(ctx.first_siginfo.si_perf_data, TEST_SIG_DATA(&ctx.iterate_on));
>  }
>
>  TEST_HARNESS_MAIN
> --
> 2.30.1
>

[PATCH v3 12/12] signalfd: Remove SIL_FAULT_PERF_EVENT fields from signalfd_siginfo

[Eric W. Beiderman]

From: "Eric W. Biederman" <ebiederm@xmission.com>

With the addition of ssi_perf_data and ssi_perf_type struct signalfd_siginfo
is dangerously close to running out of space.  All that remains is just
enough space for two additional 64bit fields.  A practice of adding all
possible siginfo_t fields into struct singalfd_siginfo can not be supported
as adding the missing fields ssi_lower, ssi_upper, and ssi_pkey would
require two 64bit fields and one 32bit fields.  In practice the fields
ssi_perf_data and ssi_perf_type can never be used by signalfd as the signal
that generates them always delivers them synchronously to the thread that
triggers them.

Therefore until someone actually needs the fields ssi_perf_data and
ssi_perf_type in signalfd_siginfo remove them.  This leaves a bit more room
for future expansion.

v1: https://lkml.kernel.org/r/20210503203814.25487-12-ebiederm@xmission.com
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
---
 fs/signalfd.c                 | 16 ++++++----------
 include/uapi/linux/signalfd.h |  4 +---
 2 files changed, 7 insertions(+), 13 deletions(-)

diff --git a/fs/signalfd.c b/fs/signalfd.c
index 335ad39f3900..040e1cf90528 100644
--- a/fs/signalfd.c
+++ b/fs/signalfd.c
@@ -114,12 +114,13 @@ static int signalfd_copyinfo(struct signalfd_siginfo __user *uinfo,
 		break;
 	case SIL_FAULT_BNDERR:
 	case SIL_FAULT_PKUERR:
+	case SIL_FAULT_PERF_EVENT:
 		/*
-		 * Fall through to the SIL_FAULT case.  Both SIL_FAULT_BNDERR
-		 * and SIL_FAULT_PKUERR are only generated by faults that
-		 * deliver them synchronously to userspace.  In case someone
-		 * injects one of these signals and signalfd catches it treat
-		 * it as SIL_FAULT.
+		 * Fall through to the SIL_FAULT case.  SIL_FAULT_BNDERR,
+		 * SIL_FAULT_PKUERR, and SIL_FAULT_PERF_EVENT are only
+		 * generated by faults that deliver them synchronously to
+		 * userspace.  In case someone injects one of these signals
+		 * and signalfd catches it treat it as SIL_FAULT.
 		 */
 	case SIL_FAULT:
 		new.ssi_addr = (long) kinfo->si_addr;
@@ -132,11 +133,6 @@ static int signalfd_copyinfo(struct signalfd_siginfo __user *uinfo,
 		new.ssi_addr = (long) kinfo->si_addr;
 		new.ssi_addr_lsb = (short) kinfo->si_addr_lsb;
 		break;
-	case SIL_FAULT_PERF_EVENT:
-		new.ssi_addr = (long) kinfo->si_addr;
-		new.ssi_perf_type = kinfo->si_perf_type;
-		new.ssi_perf_data = kinfo->si_perf_data;
-		break;
 	case SIL_CHLD:
 		new.ssi_pid    = kinfo->si_pid;
 		new.ssi_uid    = kinfo->si_uid;
diff --git a/include/uapi/linux/signalfd.h b/include/uapi/linux/signalfd.h
index e78dddf433fc..83429a05b698 100644
--- a/include/uapi/linux/signalfd.h
+++ b/include/uapi/linux/signalfd.h
@@ -39,8 +39,6 @@ struct signalfd_siginfo {
 	__s32 ssi_syscall;
 	__u64 ssi_call_addr;
 	__u32 ssi_arch;
-	__u32 ssi_perf_type;
-	__u64 ssi_perf_data;
 
 	/*
 	 * Pad strcture to 128 bytes. Remember to update the
@@ -51,7 +49,7 @@ struct signalfd_siginfo {
 	 * comes out of a read(2) and we really don't want to have
 	 * a compat on read(2).
 	 */
-	__u8 __pad[16];
+	__u8 __pad[28];
 };
 
 
-- 
2.30.1

Re: [PATCH v3 12/12] signalfd: Remove SIL_FAULT_PERF_EVENT fields from signalfd_siginfo

[Marco Elver]

On Wed, 5 May 2021 at 16:11, Eric W. Beiderman <ebiederm@xmission.com> wrote:
> From: "Eric W. Biederman" <ebiederm@xmission.com>
>
> With the addition of ssi_perf_data and ssi_perf_type struct signalfd_siginfo
> is dangerously close to running out of space.  All that remains is just
> enough space for two additional 64bit fields.  A practice of adding all
> possible siginfo_t fields into struct singalfd_siginfo can not be supported
> as adding the missing fields ssi_lower, ssi_upper, and ssi_pkey would
> require two 64bit fields and one 32bit fields.  In practice the fields
> ssi_perf_data and ssi_perf_type can never be used by signalfd as the signal
> that generates them always delivers them synchronously to the thread that
> triggers them.
>
> Therefore until someone actually needs the fields ssi_perf_data and
> ssi_perf_type in signalfd_siginfo remove them.  This leaves a bit more room
> for future expansion.
>
> v1: https://lkml.kernel.org/r/20210503203814.25487-12-ebiederm@xmission.com
> Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>

Reviewed-by: Marco Elver <elver@google.com>


> ---
>  fs/signalfd.c                 | 16 ++++++----------
>  include/uapi/linux/signalfd.h |  4 +---
>  2 files changed, 7 insertions(+), 13 deletions(-)
>
> diff --git a/fs/signalfd.c b/fs/signalfd.c
> index 335ad39f3900..040e1cf90528 100644
> --- a/fs/signalfd.c
> +++ b/fs/signalfd.c
> @@ -114,12 +114,13 @@ static int signalfd_copyinfo(struct signalfd_siginfo __user *uinfo,
>                 break;
>         case SIL_FAULT_BNDERR:
>         case SIL_FAULT_PKUERR:
> +       case SIL_FAULT_PERF_EVENT:
>                 /*
> -                * Fall through to the SIL_FAULT case.  Both SIL_FAULT_BNDERR
> -                * and SIL_FAULT_PKUERR are only generated by faults that
> -                * deliver them synchronously to userspace.  In case someone
> -                * injects one of these signals and signalfd catches it treat
> -                * it as SIL_FAULT.
> +                * Fall through to the SIL_FAULT case.  SIL_FAULT_BNDERR,
> +                * SIL_FAULT_PKUERR, and SIL_FAULT_PERF_EVENT are only
> +                * generated by faults that deliver them synchronously to
> +                * userspace.  In case someone injects one of these signals
> +                * and signalfd catches it treat it as SIL_FAULT.
>                  */
>         case SIL_FAULT:
>                 new.ssi_addr = (long) kinfo->si_addr;
> @@ -132,11 +133,6 @@ static int signalfd_copyinfo(struct signalfd_siginfo __user *uinfo,
>                 new.ssi_addr = (long) kinfo->si_addr;
>                 new.ssi_addr_lsb = (short) kinfo->si_addr_lsb;
>                 break;
> -       case SIL_FAULT_PERF_EVENT:
> -               new.ssi_addr = (long) kinfo->si_addr;
> -               new.ssi_perf_type = kinfo->si_perf_type;
> -               new.ssi_perf_data = kinfo->si_perf_data;
> -               break;
>         case SIL_CHLD:
>                 new.ssi_pid    = kinfo->si_pid;
>                 new.ssi_uid    = kinfo->si_uid;
> diff --git a/include/uapi/linux/signalfd.h b/include/uapi/linux/signalfd.h
> index e78dddf433fc..83429a05b698 100644
> --- a/include/uapi/linux/signalfd.h
> +++ b/include/uapi/linux/signalfd.h
> @@ -39,8 +39,6 @@ struct signalfd_siginfo {
>         __s32 ssi_syscall;
>         __u64 ssi_call_addr;
>         __u32 ssi_arch;
> -       __u32 ssi_perf_type;
> -       __u64 ssi_perf_data;
>
>         /*
>          * Pad strcture to 128 bytes. Remember to update the
> @@ -51,7 +49,7 @@ struct signalfd_siginfo {
>          * comes out of a read(2) and we really don't want to have
>          * a compat on read(2).
>          */
> -       __u8 __pad[16];
> +       __u8 __pad[28];
>  };
>
>
> --
> 2.30.1

Re: [PATCH v3 00/12] signal: sort out si_trapno and si_perf

[Marco Elver]

On Tue, 4 May 2021 at 23:13, Eric W. Biederman <ebiederm@xmission.com> wrote:
> This set of changes sorts out the ABI issues with SIGTRAP TRAP_PERF, and
> hopefully will can get merged before any userspace code starts using the
> new ABI.
>
> The big ideas are:
> - Placing the asserts first to prevent unexpected ABI changes
> - si_trapno becomming ordinary fault subfield.
> - struct signalfd_siginfo is almost full
>
> This set of changes starts out with Marco's static_assert changes and
> additional one of my own that enforces the fact that the alignment of
> siginfo_t is also part of the ABI.  Together these build time
> checks verify there are no unexpected ABI changes in the changes
> that follow.
>
> The field si_trapno is changed to become an ordinary extension of the
> _sigfault member of siginfo.
>
> The code is refactored a bit and then si_perf_type is added along side
> si_perf_data in the _perf subfield of _sigfault of siginfo_t.
>
> Finally the signalfd_siginfo fields are removed as they appear to be
> filling up the structure without userspace actually being able to use
> them.
>
> v2: https://lkml.kernel.org/r/m14kfjh8et.fsf_-_@fess.ebiederm.org
> v1: https://lkml.kernel.org/r/m1zgxfs7zq.fsf_-_@fess.ebiederm.org
>
> Eric W. Biederman (9):
>       signal: Verify the alignment and size of siginfo_t
>       siginfo: Move si_trapno inside the union inside _si_fault
>       signal: Implement SIL_FAULT_TRAPNO
>       signal: Use dedicated helpers to send signals with si_trapno set
>       signal: Remove __ARCH_SI_TRAPNO
>       signal: Rename SIL_PERF_EVENT SIL_FAULT_PERF_EVENT for consistency
>       signal: Factor force_sig_perf out of perf_sigtrap
>       signal: Deliver all of the siginfo perf data in _perf
>       signalfd: Remove SIL_FAULT_PERF_EVENT fields from signalfd_siginfo
>
> Marco Elver (3):
>       sparc64: Add compile-time asserts for siginfo_t offsets
>       arm: Add compile-time asserts for siginfo_t offsets
>       arm64: Add compile-time asserts for siginfo_t offsets
>
>  arch/alpha/include/uapi/asm/siginfo.h              |   2 -
>  arch/alpha/kernel/osf_sys.c                        |   2 +-
>  arch/alpha/kernel/signal.c                         |   4 +-
>  arch/alpha/kernel/traps.c                          |  24 ++---
>  arch/alpha/mm/fault.c                              |   4 +-
>  arch/arm/kernel/signal.c                           |  39 +++++++
>  arch/arm64/kernel/signal.c                         |  39 +++++++
>  arch/arm64/kernel/signal32.c                       |  39 +++++++
>  arch/mips/include/uapi/asm/siginfo.h               |   2 -
>  arch/sparc/include/uapi/asm/siginfo.h              |   3 -
>  arch/sparc/kernel/process_64.c                     |   2 +-
>  arch/sparc/kernel/signal32.c                       |  37 +++++++
>  arch/sparc/kernel/signal_64.c                      |  36 +++++++
>  arch/sparc/kernel/sys_sparc_32.c                   |   2 +-
>  arch/sparc/kernel/sys_sparc_64.c                   |   2 +-
>  arch/sparc/kernel/traps_32.c                       |  22 ++--
>  arch/sparc/kernel/traps_64.c                       |  44 ++++----
>  arch/sparc/kernel/unaligned_32.c                   |   2 +-
>  arch/sparc/mm/fault_32.c                           |   2 +-
>  arch/sparc/mm/fault_64.c                           |   2 +-
>  arch/x86/kernel/signal_compat.c                    |  15 ++-
>  fs/signalfd.c                                      |  23 ++---
>  include/linux/compat.h                             |  10 +-
>  include/linux/sched/signal.h                       |  13 +--
>  include/linux/signal.h                             |   3 +-
>  include/uapi/asm-generic/siginfo.h                 |  20 ++--
>  include/uapi/linux/signalfd.h                      |   4 +-
>  kernel/events/core.c                               |  11 +-
>  kernel/signal.c                                    | 113 +++++++++++++--------
>  .../selftests/perf_events/sigtrap_threads.c        |  12 +--
>  30 files changed, 373 insertions(+), 160 deletions(-)

Looks good, thanks a lot! I ran selftests/perf_events on x86-64, and
build-tested x86-32, arm, arm64, sparc, alpha.

I added my Reviewed/Acked-by to the various patches.

Thanks,
-- Marco

Re: [PATCH v3 00/12] signal: sort out si_trapno and si_perf

[Geert Uytterhoeven]

Hi Eric,

On Tue, May 4, 2021 at 11:14 PM Eric W. Biederman <ebiederm@xmission.com> wrote:
> This set of changes sorts out the ABI issues with SIGTRAP TRAP_PERF, and
> hopefully will can get merged before any userspace code starts using the
> new ABI.
>
> The big ideas are:
> - Placing the asserts first to prevent unexpected ABI changes
> - si_trapno becomming ordinary fault subfield.
> - struct signalfd_siginfo is almost full
>
> This set of changes starts out with Marco's static_assert changes and
> additional one of my own that enforces the fact that the alignment of
> siginfo_t is also part of the ABI.  Together these build time
> checks verify there are no unexpected ABI changes in the changes
> that follow.
>
> The field si_trapno is changed to become an ordinary extension of the
> _sigfault member of siginfo.
>
> The code is refactored a bit and then si_perf_type is added along side
> si_perf_data in the _perf subfield of _sigfault of siginfo_t.
>
> Finally the signalfd_siginfo fields are removed as they appear to be
> filling up the structure without userspace actually being able to use
> them.

Thanks for your series, which is now in next-20210506.

>  arch/alpha/include/uapi/asm/siginfo.h              |   2 -
>  arch/alpha/kernel/osf_sys.c                        |   2 +-
>  arch/alpha/kernel/signal.c                         |   4 +-
>  arch/alpha/kernel/traps.c                          |  24 ++---
>  arch/alpha/mm/fault.c                              |   4 +-
>  arch/arm/kernel/signal.c                           |  39 +++++++
>  arch/arm64/kernel/signal.c                         |  39 +++++++
>  arch/arm64/kernel/signal32.c                       |  39 +++++++
>  arch/mips/include/uapi/asm/siginfo.h               |   2 -
>  arch/sparc/include/uapi/asm/siginfo.h              |   3 -
>  arch/sparc/kernel/process_64.c                     |   2 +-
>  arch/sparc/kernel/signal32.c                       |  37 +++++++
>  arch/sparc/kernel/signal_64.c                      |  36 +++++++
>  arch/sparc/kernel/sys_sparc_32.c                   |   2 +-
>  arch/sparc/kernel/sys_sparc_64.c                   |   2 +-
>  arch/sparc/kernel/traps_32.c                       |  22 ++--
>  arch/sparc/kernel/traps_64.c                       |  44 ++++----
>  arch/sparc/kernel/unaligned_32.c                   |   2 +-
>  arch/sparc/mm/fault_32.c                           |   2 +-
>  arch/sparc/mm/fault_64.c                           |   2 +-
>  arch/x86/kernel/signal_compat.c                    |  15 ++-

No changes needed for other architectures?
All m68k configs are broken with

arch/m68k/kernel/signal.c:626:35: error: 'siginfo_t' {aka 'struct
siginfo'} has no member named 'si_perf'; did you mean 'si_errno'?

See e.g. http://kisskb.ellerman.id.au/kisskb/buildresult/14537820/

There are still a few more references left to si_perf:

$ git grep -n -w si_perf
Next/merge.log:2902:Merging userns/for-next (4cf4e48fff05 signal: sort
out si_trapno and si_perf)
arch/m68k/kernel/signal.c:626:  BUILD_BUG_ON(offsetof(siginfo_t,
si_perf) != 0x10);
include/uapi/linux/perf_event.h:467:     * siginfo_t::si_perf, e.g. to
permit user to identify the event.
tools/testing/selftests/perf_events/sigtrap_threads.c:46:/* Unique
value to check si_perf is correctly set from
perf_event_attr::sig_data. */

Thanks!

Gr{oetje,eeting}s,

                        Geert


--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds

Re: [PATCH v3 00/12] signal: sort out si_trapno and si_perf

[Marco Elver]

On Thu, May 06, 2021 at 09:00AM +0200, Geert Uytterhoeven wrote:
[...]
> No changes needed for other architectures?
> All m68k configs are broken with
> 
> arch/m68k/kernel/signal.c:626:35: error: 'siginfo_t' {aka 'struct
> siginfo'} has no member named 'si_perf'; did you mean 'si_errno'?
> 
> See e.g. http://kisskb.ellerman.id.au/kisskb/buildresult/14537820/
> 
> There are still a few more references left to si_perf:
> 
> $ git grep -n -w si_perf
> Next/merge.log:2902:Merging userns/for-next (4cf4e48fff05 signal: sort
> out si_trapno and si_perf)
> arch/m68k/kernel/signal.c:626:  BUILD_BUG_ON(offsetof(siginfo_t,
> si_perf) != 0x10);
> include/uapi/linux/perf_event.h:467:     * siginfo_t::si_perf, e.g. to
> permit user to identify the event.
> tools/testing/selftests/perf_events/sigtrap_threads.c:46:/* Unique
> value to check si_perf is correctly set from
> perf_event_attr::sig_data. */

I think we're missing the below in "signal: Deliver all of the siginfo
perf data in _perf".

Thanks,
-- Marco

------ >8 ------

diff --git a/arch/m68k/kernel/signal.c b/arch/m68k/kernel/signal.c
index a4b7ee1df211..8f215e79e70e 100644
--- a/arch/m68k/kernel/signal.c
+++ b/arch/m68k/kernel/signal.c
@@ -623,7 +623,8 @@ static inline void siginfo_build_tests(void)
 	BUILD_BUG_ON(offsetof(siginfo_t, si_pkey) != 0x12);
 
 	/* _sigfault._perf */
-	BUILD_BUG_ON(offsetof(siginfo_t, si_perf) != 0x10);
+	BUILD_BUG_ON(offsetof(siginfo_t, si_perf_data) != 0x10);
+	BUILD_BUG_ON(offsetof(siginfo_t, si_perf_type) != 0x14);
 
 	/* _sigpoll */
 	BUILD_BUG_ON(offsetof(siginfo_t, si_band)   != 0x0c);
diff --git a/include/uapi/linux/perf_event.h b/include/uapi/linux/perf_event.h
index bf8143505c49..f92880a15645 100644
--- a/include/uapi/linux/perf_event.h
+++ b/include/uapi/linux/perf_event.h
@@ -464,7 +464,7 @@ struct perf_event_attr {
 
 	/*
 	 * User provided data if sigtrap=1, passed back to user via
-	 * siginfo_t::si_perf, e.g. to permit user to identify the event.
+	 * siginfo_t::si_perf_data, e.g. to permit user to identify the event.
 	 */
 	__u64	sig_data;
 };
diff --git a/tools/testing/selftests/perf_events/sigtrap_threads.c b/tools/testing/selftests/perf_events/sigtrap_threads.c
index fde123066a8c..8e83cf91513a 100644
--- a/tools/testing/selftests/perf_events/sigtrap_threads.c
+++ b/tools/testing/selftests/perf_events/sigtrap_threads.c
@@ -43,7 +43,7 @@ static struct {
 	siginfo_t first_siginfo;	/* First observed siginfo_t. */
 } ctx;
 
-/* Unique value to check si_perf is correctly set from perf_event_attr::sig_data. */
+/* Unique value to check si_perf_data is correctly set from perf_event_attr::sig_data. */
 #define TEST_SIG_DATA(addr) (~(unsigned long)(addr))
 
 static struct perf_event_attr make_event_attr(bool enabled, volatile void *addr)

Re: [PATCH v3 00/12] signal: sort out si_trapno and si_perf

[Eric W. Biederman]

For the moment I am adding this to my for-next branch.  I plan to
respin and fold this in but I am not certain what my schedule looks like
today.  So I figure making certain I have a fix out (so I stop breaking
m68k) is more important than having a perfect patch.

Eric

From: "Eric W. Biederman" <ebiederm@xmission.com>
Date: Thu, 6 May 2021 10:17:10 -0500
Subject: [PATCH] signal: Remove the last few si_perf references

I accidentially overlooked a few references to si_perf when sorting
out the ABI update those references now.

Fixes: f6a2c711f1e3 ("signal: Deliver all of the siginfo perf data in _perf")
Suggested-by: Marco Elver <elver@google.com>
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
---
 arch/m68k/kernel/signal.c                             | 3 ++-
 include/uapi/linux/perf_event.h                       | 2 +-
 tools/testing/selftests/perf_events/sigtrap_threads.c | 2 +-
 3 files changed, 4 insertions(+), 3 deletions(-)

diff --git a/arch/m68k/kernel/signal.c b/arch/m68k/kernel/signal.c
index a4b7ee1df211..8f215e79e70e 100644
--- a/arch/m68k/kernel/signal.c
+++ b/arch/m68k/kernel/signal.c
@@ -623,7 +623,8 @@ static inline void siginfo_build_tests(void)
 	BUILD_BUG_ON(offsetof(siginfo_t, si_pkey) != 0x12);
 
 	/* _sigfault._perf */
-	BUILD_BUG_ON(offsetof(siginfo_t, si_perf) != 0x10);
+	BUILD_BUG_ON(offsetof(siginfo_t, si_perf_data) != 0x10);
+	BUILD_BUG_ON(offsetof(siginfo_t, si_perf_type) != 0x14);
 
 	/* _sigpoll */
 	BUILD_BUG_ON(offsetof(siginfo_t, si_band)   != 0x0c);
diff --git a/include/uapi/linux/perf_event.h b/include/uapi/linux/perf_event.h
index e54e639248c8..7b14753b3d38 100644
--- a/include/uapi/linux/perf_event.h
+++ b/include/uapi/linux/perf_event.h
@@ -464,7 +464,7 @@ struct perf_event_attr {
 
 	/*
 	 * User provided data if sigtrap=1, passed back to user via
-	 * siginfo_t::si_perf, e.g. to permit user to identify the event.
+	 * siginfo_t::si_perf_data, e.g. to permit user to identify the event.
 	 */
 	__u64	sig_data;
 };
diff --git a/tools/testing/selftests/perf_events/sigtrap_threads.c b/tools/testing/selftests/perf_events/sigtrap_threads.c
index fde123066a8c..8e83cf91513a 100644
--- a/tools/testing/selftests/perf_events/sigtrap_threads.c
+++ b/tools/testing/selftests/perf_events/sigtrap_threads.c
@@ -43,7 +43,7 @@ static struct {
 	siginfo_t first_siginfo;	/* First observed siginfo_t. */
 } ctx;
 
-/* Unique value to check si_perf is correctly set from perf_event_attr::sig_data. */
+/* Unique value to check si_perf_data is correctly set from perf_event_attr::sig_data. */
 #define TEST_SIG_DATA(addr) (~(unsigned long)(addr))
 
 static struct perf_event_attr make_event_attr(bool enabled, volatile void *addr)
-- 
2.30.1

Re: [PATCH v3 00/12] signal: sort out si_trapno and si_perf

[Eric W. Biederman]

Geert Uytterhoeven <geert@linux-m68k.org> writes:

> Hi Eric,
>
> On Tue, May 4, 2021 at 11:14 PM Eric W. Biederman <ebiederm@xmission.com> wrote:
>> This set of changes sorts out the ABI issues with SIGTRAP TRAP_PERF, and
>> hopefully will can get merged before any userspace code starts using the
>> new ABI.
>>
>> The big ideas are:
>> - Placing the asserts first to prevent unexpected ABI changes
>> - si_trapno becomming ordinary fault subfield.
>> - struct signalfd_siginfo is almost full
>>
>> This set of changes starts out with Marco's static_assert changes and
>> additional one of my own that enforces the fact that the alignment of
>> siginfo_t is also part of the ABI.  Together these build time
>> checks verify there are no unexpected ABI changes in the changes
>> that follow.
>>
>> The field si_trapno is changed to become an ordinary extension of the
>> _sigfault member of siginfo.
>>
>> The code is refactored a bit and then si_perf_type is added along side
>> si_perf_data in the _perf subfield of _sigfault of siginfo_t.
>>
>> Finally the signalfd_siginfo fields are removed as they appear to be
>> filling up the structure without userspace actually being able to use
>> them.
>
> Thanks for your series, which is now in next-20210506.
>
>>  arch/alpha/include/uapi/asm/siginfo.h              |   2 -
>>  arch/alpha/kernel/osf_sys.c                        |   2 +-
>>  arch/alpha/kernel/signal.c                         |   4 +-
>>  arch/alpha/kernel/traps.c                          |  24 ++---
>>  arch/alpha/mm/fault.c                              |   4 +-
>>  arch/arm/kernel/signal.c                           |  39 +++++++
>>  arch/arm64/kernel/signal.c                         |  39 +++++++
>>  arch/arm64/kernel/signal32.c                       |  39 +++++++
>>  arch/mips/include/uapi/asm/siginfo.h               |   2 -
>>  arch/sparc/include/uapi/asm/siginfo.h              |   3 -
>>  arch/sparc/kernel/process_64.c                     |   2 +-
>>  arch/sparc/kernel/signal32.c                       |  37 +++++++
>>  arch/sparc/kernel/signal_64.c                      |  36 +++++++
>>  arch/sparc/kernel/sys_sparc_32.c                   |   2 +-
>>  arch/sparc/kernel/sys_sparc_64.c                   |   2 +-
>>  arch/sparc/kernel/traps_32.c                       |  22 ++--
>>  arch/sparc/kernel/traps_64.c                       |  44 ++++----
>>  arch/sparc/kernel/unaligned_32.c                   |   2 +-
>>  arch/sparc/mm/fault_32.c                           |   2 +-
>>  arch/sparc/mm/fault_64.c                           |   2 +-
>>  arch/x86/kernel/signal_compat.c                    |  15 ++-
>
> No changes needed for other architectures?
> All m68k configs are broken with

Thanks.  I hadn't realized that si_perf asserts existed on m68k.
Thankfully linux-next caught this these.

Looking a little more deeply, it is strange that this is tested on m68k.
The architecture does not implement HAVE_PERF_EVENTS so it is impossible
for this signal to be generated.

On the off chance this these new signals will appear on m68k someday I
will update the assertion.

> arch/m68k/kernel/signal.c:626:35: error: 'siginfo_t' {aka 'struct
> siginfo'} has no member named 'si_perf'; did you mean 'si_errno'?
>
> See e.g. http://kisskb.ellerman.id.au/kisskb/buildresult/14537820/
>
> There are still a few more references left to si_perf:
>
> $ git grep -n -w si_perf
> Next/merge.log:2902:Merging userns/for-next (4cf4e48fff05 signal: sort
> out si_trapno and si_perf)
> arch/m68k/kernel/signal.c:626:  BUILD_BUG_ON(offsetof(siginfo_t,
> si_perf) != 0x10);
> include/uapi/linux/perf_event.h:467:     * siginfo_t::si_perf, e.g. to
> permit user to identify the event.
> tools/testing/selftests/perf_events/sigtrap_threads.c:46:/* Unique
> value to check si_perf is correctly set from
> perf_event_attr::sig_data. */

I will sweep them up as well.

Eric

[GIT PULL] siginfo: ABI fixes for v5.13-rc2

[Eric W. Biederman]

Linus,

Please pull the for-v5.13-rc2 branch from the git tree:

  git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace.git for-v5.13-rc2

  HEAD: addd6821190ebf1e9fece0b7848db667fd280e2e signalfd: Remove SIL_FAULT_PERF_EVENT fields from signalfd_siginfo

During the merge window an issue with si_perf and the siginfo ABI came
up.  The alpha and sparc siginfo structure layout had changed with the
addition of SIGTRAP TRAP_PERF and the new field si_perf.

The reason only alpha and sparc were affected is that they are the
only architectures that use si_trapno.

Looking deeper it was discovered that si_trapno is used for only
a few select signals on alpha and sparc, and that none of the
other _sigfault fields past si_addr are used at all.  Which means
technically no regression on alpha and sparc.

While the alignment concerns might be dismissed the abuse of
si_errno by SIGTRAP TRAP_PERF does have the potential to cause
regressions in existing userspace.

While we still have time before userspace starts using and depending on
the new definition siginfo for SIGTRAP TRAP_PERF this set of changes
cleans up siginfo_t.

- The si_trapno field is demoted from magic alpha and sparc status and
  made an ordinary union member of the _sigfault member of siginfo_t.
  Without moving it of course.

- si_perf is replaced with si_perf_data and si_perf_type ending the
  abuse of si_errno.

- BUILD_BUG_ONs are added and various helpers are modified to
  accommodate this change.

- Unnecessary additions to signalfd_siginfo are removed.

v3: https://lkml.kernel.org/r/m1tuni8ano.fsf_-_@fess.ebiederm.org
v2: https://lkml.kernel.org/r/m14kfjh8et.fsf_-_@fess.ebiederm.org
v1: https://lkml.kernel.org/r/m1zgxfs7zq.fsf_-_@fess.ebiederm.org

You might notice a recent rebase.  This code has been sitting in
linux-next as  ef566ba2d7d9 ("signal: Remove the last few si_perf
references").  Which results in the exact same code as the branch
I am sending you but the commits differ to keep git bisect working.

The difference is that I squashed a fix for a mips BUILD_BUG_ON about
si_perf into the commit that replaces si_perf with si_perf_data and
si_perf_type.  This keeps the kernel building on all architectures for
all commits keeping git-bisect working for everyone.

Eric W. Biederman (9):
      signal: Verify the alignment and size of siginfo_t
      siginfo: Move si_trapno inside the union inside _si_fault
      signal: Implement SIL_FAULT_TRAPNO
      signal: Use dedicated helpers to send signals with si_trapno set
      signal: Remove __ARCH_SI_TRAPNO
      signal: Rename SIL_PERF_EVENT SIL_FAULT_PERF_EVENT for consistency
      signal: Factor force_sig_perf out of perf_sigtrap
      signal: Deliver all of the siginfo perf data in _perf
      signalfd: Remove SIL_FAULT_PERF_EVENT fields from signalfd_siginfo

Marco Elver (3):
      sparc64: Add compile-time asserts for siginfo_t offsets
      arm: Add compile-time asserts for siginfo_t offsets
      arm64: Add compile-time asserts for siginfo_t offsets

 arch/alpha/include/uapi/asm/siginfo.h              |   2 -
 arch/alpha/kernel/osf_sys.c                        |   2 +-
 arch/alpha/kernel/signal.c                         |   4 +-
 arch/alpha/kernel/traps.c                          |  24 ++---
 arch/alpha/mm/fault.c                              |   4 +-
 arch/arm/kernel/signal.c                           |  39 +++++++
 arch/arm64/kernel/signal.c                         |  39 +++++++
 arch/arm64/kernel/signal32.c                       |  39 +++++++
 arch/m68k/kernel/signal.c                          |   3 +-
 arch/mips/include/uapi/asm/siginfo.h               |   2 -
 arch/sparc/include/uapi/asm/siginfo.h              |   3 -
 arch/sparc/kernel/process_64.c                     |   2 +-
 arch/sparc/kernel/signal32.c                       |  37 +++++++
 arch/sparc/kernel/signal_64.c                      |  36 +++++++
 arch/sparc/kernel/sys_sparc_32.c                   |   2 +-
 arch/sparc/kernel/sys_sparc_64.c                   |   2 +-
 arch/sparc/kernel/traps_32.c                       |  22 ++--
 arch/sparc/kernel/traps_64.c                       |  44 ++++----
 arch/sparc/kernel/unaligned_32.c                   |   2 +-
 arch/sparc/mm/fault_32.c                           |   2 +-
 arch/sparc/mm/fault_64.c                           |   2 +-
 arch/x86/kernel/signal_compat.c                    |  15 ++-
 fs/signalfd.c                                      |  23 ++---
 include/linux/compat.h                             |  10 +-
 include/linux/sched/signal.h                       |  13 +--
 include/linux/signal.h                             |   3 +-
 include/uapi/asm-generic/siginfo.h                 |  20 ++--
 include/uapi/linux/perf_event.h                    |   2 +-
 include/uapi/linux/signalfd.h                      |   4 +-
 kernel/events/core.c                               |  11 +-
 kernel/signal.c                                    | 113 +++++++++++++--------
 .../selftests/perf_events/sigtrap_threads.c        |  14 +--
 32 files changed, 377 insertions(+), 163 deletions(-)

Eric

Re: [GIT PULL] siginfo: ABI fixes for v5.13-rc2

[Linus Torvalds]

On Thu, May 13, 2021 at 9:55 PM Eric W. Biederman <ebiederm@xmission.com> wrote:
>
> Please pull the for-v5.13-rc2 branch from the git tree:

I really don't like this tree.

The immediate cause for "no" is the silly

 #if IS_ENABLED(CONFIG_SPARC)

and

 #if IS_ENABLED(CONFIG_ALPHA)

code in kernel/signal.c. It has absolutely zero business being there,
when those architectures have a perfectly fine arch/*/kernel/signal.c
file where that code would make much more sense *WITHOUT* any odd
preprocessor games.

But there are other oddities too, like the new

    send_sig_fault_trapno(SIGFPE, si_code, (void __user *) regs->pc,
0, current);

in the alpha code, which fundamentally seems bogus: using
send_sig_fault_trapno() with a '0' for trapno seems entirely
incorrect, since the *ONLY* point of that function is to set si_trapno
to something non-zero.

So it would seem that a plain send_sig_fault() without that 0 would be
the right thing to do.

This also mixes in a lot of other stuff than just the fixes. Which
would have been ok during the merge window, but I'm definitely not
happy about it now.

             Linus

Re: [GIT PULL] siginfo: ABI fixes for v5.13-rc2

[Eric W. Biederman]

Linus Torvalds <torvalds@linux-foundation.org> writes:

> On Thu, May 13, 2021 at 9:55 PM Eric W. Biederman <ebiederm@xmission.com> wrote:
>>
>> Please pull the for-v5.13-rc2 branch from the git tree:
>
> I really don't like this tree.
>
> The immediate cause for "no" is the silly
>
>  #if IS_ENABLED(CONFIG_SPARC)
>
> and
>
>  #if IS_ENABLED(CONFIG_ALPHA)
>
> code in kernel/signal.c. It has absolutely zero business being there,
> when those architectures have a perfectly fine arch/*/kernel/signal.c
> file where that code would make much more sense *WITHOUT* any odd
> preprocessor games.

The code is generic it just happens those functions are only used on
sparc and alpha.  Further I really want to make filling out siginfo_t
happen in dedicated functions as much as possible in kernel/signal.c.
The probably of getting it wrong without a helper functions is very
strong.  As the code I am fixing demonstrates.

The IS_ENABLED(arch) is mostly there so we can delete the code if/when
the architectures are retired in another decade or so.

> But there are other oddities too, like the new
>
>     send_sig_fault_trapno(SIGFPE, si_code, (void __user *) regs->pc,
> 0, current);
>
> in the alpha code, which fundamentally seems bogus: using
> send_sig_fault_trapno() with a '0' for trapno seems entirely
> incorrect, since the *ONLY* point of that function is to set si_trapno
> to something non-zero.
>
> So it would seem that a plain send_sig_fault() without that 0 would be
> the right thing to do.

As it happens the floating point emulation code on alpha is inconsistent
with the non floating point emulation code.  When using real floating
point hardware SIGFPE on alpha always set si_trapno.  The floating point
emulation code does not look like it has ever set si_trapno.

I continued to used send_sig_fault_trapno to point out that
inconsistency.

If alpha floating point emulation was in active use I expect we would
care enough to put something other than 0 in there.

> This also mixes in a lot of other stuff than just the fixes. Which
> would have been ok during the merge window, but I'm definitely not
> happy about it now.

If the breakage that came with SIGTRAP TRAP_PERF had not been discovered
during the merge window I would not be sending this now.  It took a
little time to dig to the bottom, then the code needed just a little
extra time to sit, so there were not surprises.

As for mixing things, I am not quite certain what you are referring to.
All of the changes relate to keeping people from shooting themselves
in the foot with when using siginfo.

The most noise comes from send_sig_fault vs send_sig_fault_trapno, and
force_sig_fault vs force_sig_fault_trapno.  That is fundamental to the
siginfo fix as it is there to ensure that is safe to treat si_trapno
as an ordinary _sigfault union member.  Which in turns makes alpha
and sparc no longer special with respect to _sigfault, just a little
eccentric.

I will concede that renaming SIL_PERF_EVENT to SIL_FAULT_PERF_EVENT is
unnecessary, but it certainly makes it clear that we are dealing
with _sigfault and not some other part of siginfo_t.

Eric

Re: [GIT PULL] siginfo: ABI fixes for v5.13-rc2

[Eric W. Biederman]

ebiederm@xmission.com (Eric W. Biederman) writes:

> Linus Torvalds <torvalds@linux-foundation.org> writes:
>
>> On Thu, May 13, 2021 at 9:55 PM Eric W. Biederman <ebiederm@xmission.com> wrote:
>>>
>>> Please pull the for-v5.13-rc2 branch from the git tree:
>>
>> I really don't like this tree.
>>
>> The immediate cause for "no" is the silly
>>
>>  #if IS_ENABLED(CONFIG_SPARC)
>>
>> and
>>
>>  #if IS_ENABLED(CONFIG_ALPHA)
>>
>> code in kernel/signal.c. It has absolutely zero business being there,
>> when those architectures have a perfectly fine arch/*/kernel/signal.c
>> file where that code would make much more sense *WITHOUT* any odd
>> preprocessor games.
>
> The code is generic it just happens those functions are only used on
> sparc and alpha.  Further I really want to make filling out siginfo_t
> happen in dedicated functions as much as possible in kernel/signal.c.
> The probably of getting it wrong without a helper functions is very
> strong.  As the code I am fixing demonstrates.
>
> The IS_ENABLED(arch) is mostly there so we can delete the code if/when
> the architectures are retired in another decade or so.

There is also the question of why alpha allows userspace to block
SIGFPE.

If it turns out that alpha is just silly by allowing synchronous
exceptions to be blocked, then the code really becomes generic and
shared shared between sparc and alpha.

Which is really why the code does not make sense in some architecture
specific version of signal.c.  That and the fact the two functions
are almost identical.

If you want I can remove the #ifdefs and we can take up slightly more
space until someone implements -ffunction-sections.

Do you know if alpha will be stuck triggering the same floating point
error if the SIGFPE is blocked or can alpha somehow continue past it?

If alpha using send_sig instead of force_sig is historical and does not
reflect the reality of the hardware alpha can be converted and several
of the send_sig variants can be removed.  Otherwise alpha remains the
odd man out, and the code can remain until all of the alpha hardware
dies.  (I don't think anyone is manufacturing alpha hardware anymore).

I would look it up but I have lost access to whatever alpha
documentation I had.

Eric

Re: [GIT PULL] siginfo: ABI fixes for v5.13-rc2

[Ingo Molnar]

* Eric W. Biederman <ebiederm@xmission.com> wrote:

> Looking deeper it was discovered that si_trapno is used for only
> a few select signals on alpha and sparc, and that none of the
> other _sigfault fields past si_addr are used at all.  Which means
> technically no regression on alpha and sparc.

If there's no functional regression on any platform, could much of this 
wait until v5.14, or do we want some of these cleanups right now?

The fixes seem to be for long-existing bugs, not fresh regressions, AFAICS. 
The asserts & cleanups are useful, but not regression fixes.

I.e. this is a bit scary:

>  32 files changed, 377 insertions(+), 163 deletions(-)

at -rc2 time.

Thanks,

	Ingo

Re: [GIT PULL] siginfo: ABI fixes for v5.13-rc2

[Eric W. Biederman]

Ingo Molnar <mingo@kernel.org> writes:

> * Eric W. Biederman <ebiederm@xmission.com> wrote:
>
>> Looking deeper it was discovered that si_trapno is used for only
>> a few select signals on alpha and sparc, and that none of the
>> other _sigfault fields past si_addr are used at all.  Which means
>> technically no regression on alpha and sparc.
>
> If there's no functional regression on any platform, could much of this 
> wait until v5.14, or do we want some of these cleanups right now?
>
> The fixes seem to be for long-existing bugs, not fresh regressions, AFAICS. 
> The asserts & cleanups are useful, but not regression fixes.
>
> I.e. this is a bit scary:

The new ABI for SIGTRAP TRAP perf that came in the merge window is
broken and wrong.  We need to revert/disable the new SIGTRAP TRAP_PERF
or have a fix before v5.13.

The issue is old crap getting in the way of a new addition.  I think I
might see a smaller code change on how to get to something compatible
with this.

>>  32 files changed, 377 insertions(+), 163 deletions(-)
>
> at -rc2 time.

The additions are all tests to make certain everything is fine.
The actual code change without the assertions (tests) is essentially
a wash.

Eric

[GIT PULL] siginfo: ABI fixes for v5.13-rc3

[Eric W. Biederman]

Linus,

Please pull the for-v5.13-rc3 branch from the git tree:

  git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace.git for-v5.13-rc3

  HEAD: 922e3013046b79b444c87eda5baf43afae1326a8 signalfd: Remove SIL_FAULT_PERF_EVENT fields from signalfd_siginfo


During the merge window an issue with si_perf and the siginfo ABI came
up.  The alpha and sparc siginfo structure layout had changed with the
addition of SIGTRAP TRAP_PERF and the new field si_perf.

The reason only alpha and sparc were affected is that they are the
only architectures that use si_trapno.

Looking deeper it was discovered that si_trapno is used for only
a few select signals on alpha and sparc, and that none of the
other _sigfault fields past si_addr are used at all.  Which means
technically no regression on alpha and sparc.

While the alignment concerns might be dismissed the abuse of
si_errno by SIGTRAP TRAP_PERF does have the potential to cause
regressions in existing userspace.

While we still have time before userspace starts using and depending on
the new definition siginfo for SIGTRAP TRAP_PERF this set of changes
cleans up siginfo_t.

- The si_trapno field is demoted from magic alpha and sparc status and
  made an ordinary union member of the _sigfault member of siginfo_t.
  Without moving it of course.

- si_perf is replaced with si_perf_data and si_perf_type ending the
  abuse of si_errno.

- Unnecessary additions to signalfd_siginfo are removed.

v4: https://lkml.kernel.org/r/m1a6ot5e2h.fsf_-_@fess.ebiederm.org
v3: https://lkml.kernel.org/r/m1tuni8ano.fsf_-_@fess.ebiederm.org
v2: https://lkml.kernel.org/r/m14kfjh8et.fsf_-_@fess.ebiederm.org
v1: https://lkml.kernel.org/r/m1zgxfs7zq.fsf_-_@fess.ebiederm.org

This version drops the tests and fine grained handling of si_trapno
on alpha and sparc (replaced assuming si_trapno is valid for
all but the faults that defined different data).

Hopefully this is enough to not be scary as a fix for the ABI issues.

Tested-by: Marco Elver <elver@google.com>

Eric W. Biederman (5):
      siginfo: Move si_trapno inside the union inside _si_fault
      signal: Implement SIL_FAULT_TRAPNO
      signal: Factor force_sig_perf out of perf_sigtrap
      signal: Deliver all of the siginfo perf data in _perf
      signalfd: Remove SIL_PERF_EVENT fields from signalfd_siginfo


 arch/m68k/kernel/signal.c                          |  3 +-
 arch/x86/kernel/signal_compat.c                    |  9 +++-
 fs/signalfd.c                                      | 23 ++++-----
 include/linux/compat.h                             | 10 ++--
 include/linux/sched/signal.h                       |  1 +
 include/linux/signal.h                             |  1 +
 include/uapi/asm-generic/siginfo.h                 | 15 +++---
 include/uapi/linux/perf_event.h                    |  2 +-
 include/uapi/linux/signalfd.h                      |  4 +-
 kernel/events/core.c                               | 11 +---
 kernel/signal.c                                    | 59 +++++++++++++---------
 .../selftests/perf_events/sigtrap_threads.c        | 14 ++---
 12 files changed, 79 insertions(+), 73 deletions(-)

Eric

Re: [GIT PULL] siginfo: ABI fixes for v5.13-rc3

[pr-tracker-bot]

The pull request you sent on Fri, 21 May 2021 09:59:53 -0500:

> git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace.git for-v5.13-rc3

has been merged into torvalds/linux.git:
https://git.kernel.org/torvalds/c/a0e31f3a38e77612ed8967aaad28db6d3ee674b5

Thank you!

-- 
Deet-doot-dot, I am a bot.
https://korg.docs.kernel.org/prtracker.html

[PATCH v4 0/5] siginfo: ABI fixes for TRAP_PERF

[Eric W. Biederman]

During the merge window an issue with si_perf and the siginfo ABI came
up.  The alpha and sparc siginfo structure layout had changed with the
addition of SIGTRAP TRAP_PERF and the new field si_perf.

The reason only alpha and sparc were affected is that they are the
only architectures that use si_trapno.

Looking deeper it was discovered that si_trapno is used for only
a few select signals on alpha and sparc, and that none of the
other _sigfault fields past si_addr are used at all.  Which means
technically no regression on alpha and sparc.

While the alignment concerns might be dismissed the abuse of
si_errno by SIGTRAP TRAP_PERF does have the potential to cause
regressions in existing userspace.

While we still have time before userspace starts using and depending on
the new definition siginfo for SIGTRAP TRAP_PERF this set of changes
cleans up siginfo_t.

- The si_trapno field is demoted from magic alpha and sparc status and
  made an ordinary union member of the _sigfault member of siginfo_t.
  Without moving it of course.

- si_perf is replaced with si_perf_data and si_perf_type ending the
  abuse of si_errno.

- Unnecessary additions to signalfd_siginfo are removed.

v3: https://lkml.kernel.org/r/m1tuni8ano.fsf_-_@fess.ebiederm.org
v2: https://lkml.kernel.org/r/m14kfjh8et.fsf_-_@fess.ebiederm.org
v1: https://lkml.kernel.org/r/m1zgxfs7zq.fsf_-_@fess.ebiederm.org

This version drops the tests and fine grained handling of si_trapno
on alpha and sparc (replaced assuming si_trapno is valid for
all but the faults that defined different data).

Eric W. Biederman (5):
      siginfo: Move si_trapno inside the union inside _si_fault
      signal: Implement SIL_FAULT_TRAPNO
      signal: Factor force_sig_perf out of perf_sigtrap
      signal: Deliver all of the siginfo perf data in _perf
      signalfd: Remove SIL_PERF_EVENT fields from signalfd_siginfo


 arch/m68k/kernel/signal.c                          |  3 +-
 arch/x86/kernel/signal_compat.c                    |  9 +++-
 fs/signalfd.c                                      | 23 ++++-----
 include/linux/compat.h                             | 10 ++--
 include/linux/sched/signal.h                       |  1 +
 include/linux/signal.h                             |  1 +
 include/uapi/asm-generic/siginfo.h                 | 15 +++---
 include/uapi/linux/perf_event.h                    |  2 +-
 include/uapi/linux/signalfd.h                      |  4 +-
 kernel/events/core.c                               | 11 +---
 kernel/signal.c                                    | 59 +++++++++++++---------
 .../selftests/perf_events/sigtrap_threads.c        | 14 ++---
 12 files changed, 79 insertions(+), 73 deletions(-)

[PATCH v4 1/5] siginfo: Move si_trapno inside the union inside _si_fault

[Eric W. Beiderman]

From: "Eric W. Biederman" <ebiederm@xmission.com>

It turns out that linux uses si_trapno very sparingly, and as such it
can be considered extra information for a very narrow selection of
signals, rather than information that is present with every fault
reported in siginfo.

As such move si_trapno inside the union inside of _si_fault.  This
results in no change in placement, and makes it eaiser
to extend _si_fault in the future as this reduces the number of
special cases.  In particular with si_trapno included in the union it
is no longer a concern that the union must be pointer aligned on most
architectures because the union follows immediately after si_addr
which is a pointer.

This change results in a difference in siginfo field placement on
sparc and alpha for the fields si_addr_lsb, si_lower, si_upper,
si_pkey, and si_perf.  These architectures do not implement the
signals that would use si_addr_lsb, si_lower, si_upper, si_pkey, and
si_perf.  Further these architecture have not yet implemented the
userspace that would use si_perf.

The point of this change is in fact to correct these placement issues
before sparc or alpha grow userspace that cares.  This change was
discussed[1] and the agreement is that this change is currently safe.

[1]: https://lkml.kernel.org/r/CAK8P3a0+uKYwL1NhY6Hvtieghba2hKYGD6hcKx5n8=4Gtt+pHA@mail.gmail.com
Acked-by: Marco Elver <elver@google.com>
v1: https://lkml.kernel.org/r/m1tunns7yf.fsf_-_@fess.ebiederm.org
v2: https://lkml.kernel.org/r/20210505141101.11519-5-ebiederm@xmission.com
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
---
 arch/x86/kernel/signal_compat.c    | 3 +++
 include/linux/compat.h             | 5 ++---
 include/uapi/asm-generic/siginfo.h | 7 ++-----
 kernel/signal.c                    | 1 +
 4 files changed, 8 insertions(+), 8 deletions(-)

diff --git a/arch/x86/kernel/signal_compat.c b/arch/x86/kernel/signal_compat.c
index 0e5d0a7e203b..a9fcabd8a5e5 100644
--- a/arch/x86/kernel/signal_compat.c
+++ b/arch/x86/kernel/signal_compat.c
@@ -127,6 +127,9 @@ static inline void signal_compat_build_tests(void)
 	BUILD_BUG_ON(offsetof(siginfo_t, si_addr) != 0x10);
 	BUILD_BUG_ON(offsetof(compat_siginfo_t, si_addr) != 0x0C);
 
+	BUILD_BUG_ON(offsetof(siginfo_t, si_trapno) != 0x18);
+	BUILD_BUG_ON(offsetof(compat_siginfo_t, si_trapno) != 0x10);
+
 	BUILD_BUG_ON(offsetof(siginfo_t, si_addr_lsb) != 0x18);
 	BUILD_BUG_ON(offsetof(compat_siginfo_t, si_addr_lsb) != 0x10);
 
diff --git a/include/linux/compat.h b/include/linux/compat.h
index f0d2dd35d408..6af7bef15e94 100644
--- a/include/linux/compat.h
+++ b/include/linux/compat.h
@@ -214,12 +214,11 @@ typedef struct compat_siginfo {
 		/* SIGILL, SIGFPE, SIGSEGV, SIGBUS, SIGTRAP, SIGEMT */
 		struct {
 			compat_uptr_t _addr;	/* faulting insn/memory ref. */
-#ifdef __ARCH_SI_TRAPNO
-			int _trapno;	/* TRAP # which caused the signal */
-#endif
 #define __COMPAT_ADDR_BND_PKEY_PAD  (__alignof__(compat_uptr_t) < sizeof(short) ? \
 				     sizeof(short) : __alignof__(compat_uptr_t))
 			union {
+				/* used on alpha and sparc */
+				int _trapno;	/* TRAP # which caused the signal */
 				/*
 				 * used when si_code=BUS_MCEERR_AR or
 				 * used when si_code=BUS_MCEERR_AO
diff --git a/include/uapi/asm-generic/siginfo.h b/include/uapi/asm-generic/siginfo.h
index 03d6f6d2c1fe..e663bf117b46 100644
--- a/include/uapi/asm-generic/siginfo.h
+++ b/include/uapi/asm-generic/siginfo.h
@@ -63,9 +63,6 @@ union __sifields {
 	/* SIGILL, SIGFPE, SIGSEGV, SIGBUS, SIGTRAP, SIGEMT */
 	struct {
 		void __user *_addr; /* faulting insn/memory ref. */
-#ifdef __ARCH_SI_TRAPNO
-		int _trapno;	/* TRAP # which caused the signal */
-#endif
 #ifdef __ia64__
 		int _imm;		/* immediate value for "break" */
 		unsigned int _flags;	/* see ia64 si_flags */
@@ -75,6 +72,8 @@ union __sifields {
 #define __ADDR_BND_PKEY_PAD  (__alignof__(void *) < sizeof(short) ? \
 			      sizeof(short) : __alignof__(void *))
 		union {
+			/* used on alpha and sparc */
+			int _trapno;	/* TRAP # which caused the signal */
 			/*
 			 * used when si_code=BUS_MCEERR_AR or
 			 * used when si_code=BUS_MCEERR_AO
@@ -150,9 +149,7 @@ typedef struct siginfo {
 #define si_int		_sifields._rt._sigval.sival_int
 #define si_ptr		_sifields._rt._sigval.sival_ptr
 #define si_addr		_sifields._sigfault._addr
-#ifdef __ARCH_SI_TRAPNO
 #define si_trapno	_sifields._sigfault._trapno
-#endif
 #define si_addr_lsb	_sifields._sigfault._addr_lsb
 #define si_lower	_sifields._sigfault._addr_bnd._lower
 #define si_upper	_sifields._sigfault._addr_bnd._upper
diff --git a/kernel/signal.c b/kernel/signal.c
index c3017aa8024a..65888aec65a0 100644
--- a/kernel/signal.c
+++ b/kernel/signal.c
@@ -4607,6 +4607,7 @@ static inline void siginfo_buildtime_checks(void)
 
 	/* sigfault */
 	CHECK_OFFSET(si_addr);
+	CHECK_OFFSET(si_trapno);
 	CHECK_OFFSET(si_addr_lsb);
 	CHECK_OFFSET(si_lower);
 	CHECK_OFFSET(si_upper);
-- 
2.30.1

[PATCH v4 2/5] signal: Implement SIL_FAULT_TRAPNO

[Eric W. Beiderman]

From: "Eric W. Biederman" <ebiederm@xmission.com>

Now that si_trapno is part of the union in _si_fault and available on
all architectures, add SIL_FAULT_TRAPNO and update siginfo_layout to
return SIL_FAULT_TRAPNO when the code assumes si_trapno is valid.

There is room for future changes to reduce when si_trapno is valid but
this is all that is needed to make si_trapno and the other members of
the the union in _sigfault mutually exclusive.

Update the code that uses siginfo_layout to deal with SIL_FAULT_TRAPNO
and have the same code ignore si_trapno in in all other cases.

v1: https://lkml.kernel.org/r/m1o8dvs7s7.fsf_-_@fess.ebiederm.org
v2: https://lkml.kernel.org/r/20210505141101.11519-6-ebiederm@xmission.com
Reviewed-by: Marco Elver <elver@google.com>
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
---
 fs/signalfd.c          |  8 +++-----
 include/linux/signal.h |  1 +
 kernel/signal.c        | 34 ++++++++++++----------------------
 3 files changed, 16 insertions(+), 27 deletions(-)

diff --git a/fs/signalfd.c b/fs/signalfd.c
index 040a1142915f..e87e59581653 100644
--- a/fs/signalfd.c
+++ b/fs/signalfd.c
@@ -123,15 +123,13 @@ static int signalfd_copyinfo(struct signalfd_siginfo __user *uinfo,
 		 */
 	case SIL_FAULT:
 		new.ssi_addr = (long) kinfo->si_addr;
-#ifdef __ARCH_SI_TRAPNO
+		break;
+	case SIL_FAULT_TRAPNO:
+		new.ssi_addr = (long) kinfo->si_addr;
 		new.ssi_trapno = kinfo->si_trapno;
-#endif
 		break;
 	case SIL_FAULT_MCEERR:
 		new.ssi_addr = (long) kinfo->si_addr;
-#ifdef __ARCH_SI_TRAPNO
-		new.ssi_trapno = kinfo->si_trapno;
-#endif
 		new.ssi_addr_lsb = (short) kinfo->si_addr_lsb;
 		break;
 	case SIL_PERF_EVENT:
diff --git a/include/linux/signal.h b/include/linux/signal.h
index 1e98548d7cf6..5160fd45e5ca 100644
--- a/include/linux/signal.h
+++ b/include/linux/signal.h
@@ -40,6 +40,7 @@ enum siginfo_layout {
 	SIL_TIMER,
 	SIL_POLL,
 	SIL_FAULT,
+	SIL_FAULT_TRAPNO,
 	SIL_FAULT_MCEERR,
 	SIL_FAULT_BNDERR,
 	SIL_FAULT_PKUERR,
diff --git a/kernel/signal.c b/kernel/signal.c
index 65888aec65a0..597594ee72de 100644
--- a/kernel/signal.c
+++ b/kernel/signal.c
@@ -1194,6 +1194,7 @@ static inline bool has_si_pid_and_uid(struct kernel_siginfo *info)
 	case SIL_TIMER:
 	case SIL_POLL:
 	case SIL_FAULT:
+	case SIL_FAULT_TRAPNO:
 	case SIL_FAULT_MCEERR:
 	case SIL_FAULT_BNDERR:
 	case SIL_FAULT_PKUERR:
@@ -2527,6 +2528,7 @@ static void hide_si_addr_tag_bits(struct ksignal *ksig)
 {
 	switch (siginfo_layout(ksig->sig, ksig->info.si_code)) {
 	case SIL_FAULT:
+	case SIL_FAULT_TRAPNO:
 	case SIL_FAULT_MCEERR:
 	case SIL_FAULT_BNDERR:
 	case SIL_FAULT_PKUERR:
@@ -3214,6 +3216,10 @@ enum siginfo_layout siginfo_layout(unsigned sig, int si_code)
 #endif
 			else if ((sig == SIGTRAP) && (si_code == TRAP_PERF))
 				layout = SIL_PERF_EVENT;
+#ifdef __ARCH_SI_TRAPNO
+			else if (layout == SIL_FAULT)
+				layout = SIL_FAULT_TRAPNO;
+#endif
 		}
 		else if (si_code <= NSIGPOLL)
 			layout = SIL_POLL;
@@ -3317,30 +3323,22 @@ void copy_siginfo_to_external32(struct compat_siginfo *to,
 		break;
 	case SIL_FAULT:
 		to->si_addr = ptr_to_compat(from->si_addr);
-#ifdef __ARCH_SI_TRAPNO
+		break;
+	case SIL_FAULT_TRAPNO:
+		to->si_addr = ptr_to_compat(from->si_addr);
 		to->si_trapno = from->si_trapno;
-#endif
 		break;
 	case SIL_FAULT_MCEERR:
 		to->si_addr = ptr_to_compat(from->si_addr);
-#ifdef __ARCH_SI_TRAPNO
-		to->si_trapno = from->si_trapno;
-#endif
 		to->si_addr_lsb = from->si_addr_lsb;
 		break;
 	case SIL_FAULT_BNDERR:
 		to->si_addr = ptr_to_compat(from->si_addr);
-#ifdef __ARCH_SI_TRAPNO
-		to->si_trapno = from->si_trapno;
-#endif
 		to->si_lower = ptr_to_compat(from->si_lower);
 		to->si_upper = ptr_to_compat(from->si_upper);
 		break;
 	case SIL_FAULT_PKUERR:
 		to->si_addr = ptr_to_compat(from->si_addr);
-#ifdef __ARCH_SI_TRAPNO
-		to->si_trapno = from->si_trapno;
-#endif
 		to->si_pkey = from->si_pkey;
 		break;
 	case SIL_PERF_EVENT:
@@ -3401,30 +3399,22 @@ static int post_copy_siginfo_from_user32(kernel_siginfo_t *to,
 		break;
 	case SIL_FAULT:
 		to->si_addr = compat_ptr(from->si_addr);
-#ifdef __ARCH_SI_TRAPNO
+		break;
+	case SIL_FAULT_TRAPNO:
+		to->si_addr = compat_ptr(from->si_addr);
 		to->si_trapno = from->si_trapno;
-#endif
 		break;
 	case SIL_FAULT_MCEERR:
 		to->si_addr = compat_ptr(from->si_addr);
-#ifdef __ARCH_SI_TRAPNO
-		to->si_trapno = from->si_trapno;
-#endif
 		to->si_addr_lsb = from->si_addr_lsb;
 		break;
 	case SIL_FAULT_BNDERR:
 		to->si_addr = compat_ptr(from->si_addr);
-#ifdef __ARCH_SI_TRAPNO
-		to->si_trapno = from->si_trapno;
-#endif
 		to->si_lower = compat_ptr(from->si_lower);
 		to->si_upper = compat_ptr(from->si_upper);
 		break;
 	case SIL_FAULT_PKUERR:
 		to->si_addr = compat_ptr(from->si_addr);
-#ifdef __ARCH_SI_TRAPNO
-		to->si_trapno = from->si_trapno;
-#endif
 		to->si_pkey = from->si_pkey;
 		break;
 	case SIL_PERF_EVENT:
-- 
2.30.1

[PATCH v4 3/5] signal: Factor force_sig_perf out of perf_sigtrap

[Eric W. Beiderman]

From: "Eric W. Biederman" <ebiederm@xmission.com>

Separate filling in siginfo for TRAP_PERF from deciding that
siginal needs to be sent.

There are enough little details that need to be correct when
properly filling in siginfo_t that it is easy to make mistakes
if filling in the siginfo_t is in the same function with other
logic.  So factor out force_sig_perf to reduce the cognative
load of on reviewers, maintainers and implementors.

v1: https://lkml.kernel.org/r/m17dkjqqxz.fsf_-_@fess.ebiederm.org
v2: https://lkml.kernel.org/r/20210505141101.11519-10-ebiederm@xmission.com
Reviewed-by: Marco Elver <elver@google.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
---
 include/linux/sched/signal.h |  1 +
 kernel/events/core.c         | 11 ++---------
 kernel/signal.c              | 13 +++++++++++++
 3 files changed, 16 insertions(+), 9 deletions(-)

diff --git a/include/linux/sched/signal.h b/include/linux/sched/signal.h
index 3f6a0fcaa10c..7f4278fa21fe 100644
--- a/include/linux/sched/signal.h
+++ b/include/linux/sched/signal.h
@@ -326,6 +326,7 @@ int send_sig_mceerr(int code, void __user *, short, struct task_struct *);
 
 int force_sig_bnderr(void __user *addr, void __user *lower, void __user *upper);
 int force_sig_pkuerr(void __user *addr, u32 pkey);
+int force_sig_perf(void __user *addr, u32 type, u64 sig_data);
 
 int force_sig_ptrace_errno_trap(int errno, void __user *addr);
 
diff --git a/kernel/events/core.c b/kernel/events/core.c
index 928b166d888e..48ea8863183b 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -6394,8 +6394,6 @@ void perf_event_wakeup(struct perf_event *event)
 
 static void perf_sigtrap(struct perf_event *event)
 {
-	struct kernel_siginfo info;
-
 	/*
 	 * We'd expect this to only occur if the irq_work is delayed and either
 	 * ctx->task or current has changed in the meantime. This can be the
@@ -6410,13 +6408,8 @@ static void perf_sigtrap(struct perf_event *event)
 	if (current->flags & PF_EXITING)
 		return;
 
-	clear_siginfo(&info);
-	info.si_signo = SIGTRAP;
-	info.si_code = TRAP_PERF;
-	info.si_errno = event->attr.type;
-	info.si_perf = event->attr.sig_data;
-	info.si_addr = (void __user *)event->pending_addr;
-	force_sig_info(&info);
+	force_sig_perf((void __user *)event->pending_addr,
+		       event->attr.type, event->attr.sig_data);
 }
 
 static void perf_pending_event_disable(struct perf_event *event)
diff --git a/kernel/signal.c b/kernel/signal.c
index 597594ee72de..3a18d13c39b2 100644
--- a/kernel/signal.c
+++ b/kernel/signal.c
@@ -1763,6 +1763,19 @@ int force_sig_pkuerr(void __user *addr, u32 pkey)
 }
 #endif
 
+int force_sig_perf(void __user *addr, u32 type, u64 sig_data)
+{
+	struct kernel_siginfo info;
+
+	clear_siginfo(&info);
+	info.si_signo = SIGTRAP;
+	info.si_errno = type;
+	info.si_code  = TRAP_PERF;
+	info.si_addr  = addr;
+	info.si_perf  = sig_data;
+	return force_sig_info(&info);
+}
+
 /* For the crazy architectures that include trap information in
  * the errno field, instead of an actual errno value.
  */
-- 
2.30.1

[PATCH v4 4/5] signal: Deliver all of the siginfo perf data in _perf

[Eric W. Beiderman]

From: "Eric W. Biederman" <ebiederm@xmission.com>

Don't abuse si_errno and deliver all of the perf data in _perf member
of siginfo_t.

Note: The data field in the perf data structures in a u64 to allow a
pointer to be encoded without needed to implement a 32bit and 64bit
version of the same structure.  There already exists a 32bit and 64bit
versions siginfo_t, and the 32bit version can not include a 64bit
member as it only has 32bit alignment.  So unsigned long is used in
siginfo_t instead of a u64 as unsigned long can encode a pointer on
all architectures linux supports.

v1: https://lkml.kernel.org/r/m11rarqqx2.fsf_-_@fess.ebiederm.org
v2: https://lkml.kernel.org/r/20210503203814.25487-10-ebiederm@xmission.com
v3: https://lkml.kernel.org/r/20210505141101.11519-11-ebiederm@xmission.com
Reviewed-by: Marco Elver <elver@google.com>
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
---
 arch/m68k/kernel/signal.c                     |  3 ++-
 arch/x86/kernel/signal_compat.c               |  6 ++++--
 fs/signalfd.c                                 |  3 ++-
 include/linux/compat.h                        |  5 ++++-
 include/uapi/asm-generic/siginfo.h            |  8 +++++--
 include/uapi/linux/perf_event.h               |  2 +-
 include/uapi/linux/signalfd.h                 |  4 ++--
 kernel/signal.c                               | 21 ++++++++++++-------
 .../selftests/perf_events/sigtrap_threads.c   | 14 ++++++-------
 9 files changed, 41 insertions(+), 25 deletions(-)

diff --git a/arch/m68k/kernel/signal.c b/arch/m68k/kernel/signal.c
index a4b7ee1df211..8f215e79e70e 100644
--- a/arch/m68k/kernel/signal.c
+++ b/arch/m68k/kernel/signal.c
@@ -623,7 +623,8 @@ static inline void siginfo_build_tests(void)
 	BUILD_BUG_ON(offsetof(siginfo_t, si_pkey) != 0x12);
 
 	/* _sigfault._perf */
-	BUILD_BUG_ON(offsetof(siginfo_t, si_perf) != 0x10);
+	BUILD_BUG_ON(offsetof(siginfo_t, si_perf_data) != 0x10);
+	BUILD_BUG_ON(offsetof(siginfo_t, si_perf_type) != 0x14);
 
 	/* _sigpoll */
 	BUILD_BUG_ON(offsetof(siginfo_t, si_band)   != 0x0c);
diff --git a/arch/x86/kernel/signal_compat.c b/arch/x86/kernel/signal_compat.c
index a9fcabd8a5e5..06743ec054d2 100644
--- a/arch/x86/kernel/signal_compat.c
+++ b/arch/x86/kernel/signal_compat.c
@@ -141,8 +141,10 @@ static inline void signal_compat_build_tests(void)
 	BUILD_BUG_ON(offsetof(siginfo_t, si_pkey) != 0x20);
 	BUILD_BUG_ON(offsetof(compat_siginfo_t, si_pkey) != 0x14);
 
-	BUILD_BUG_ON(offsetof(siginfo_t, si_perf) != 0x18);
-	BUILD_BUG_ON(offsetof(compat_siginfo_t, si_perf) != 0x10);
+	BUILD_BUG_ON(offsetof(siginfo_t, si_perf_data) != 0x18);
+	BUILD_BUG_ON(offsetof(siginfo_t, si_perf_type) != 0x20);
+	BUILD_BUG_ON(offsetof(compat_siginfo_t, si_perf_data) != 0x10);
+	BUILD_BUG_ON(offsetof(compat_siginfo_t, si_perf_type) != 0x14);
 
 	CHECK_CSI_OFFSET(_sigpoll);
 	CHECK_CSI_SIZE  (_sigpoll, 2*sizeof(int));
diff --git a/fs/signalfd.c b/fs/signalfd.c
index e87e59581653..373df2f12415 100644
--- a/fs/signalfd.c
+++ b/fs/signalfd.c
@@ -134,7 +134,8 @@ static int signalfd_copyinfo(struct signalfd_siginfo __user *uinfo,
 		break;
 	case SIL_PERF_EVENT:
 		new.ssi_addr = (long) kinfo->si_addr;
-		new.ssi_perf = kinfo->si_perf;
+		new.ssi_perf_type = kinfo->si_perf_type;
+		new.ssi_perf_data = kinfo->si_perf_data;
 		break;
 	case SIL_CHLD:
 		new.ssi_pid    = kinfo->si_pid;
diff --git a/include/linux/compat.h b/include/linux/compat.h
index 6af7bef15e94..a27fffaae121 100644
--- a/include/linux/compat.h
+++ b/include/linux/compat.h
@@ -236,7 +236,10 @@ typedef struct compat_siginfo {
 					u32 _pkey;
 				} _addr_pkey;
 				/* used when si_code=TRAP_PERF */
-				compat_ulong_t _perf;
+				struct {
+					compat_ulong_t _data;
+					u32 _type;
+				} _perf;
 			};
 		} _sigfault;
 
diff --git a/include/uapi/asm-generic/siginfo.h b/include/uapi/asm-generic/siginfo.h
index e663bf117b46..5a3c221f4c9d 100644
--- a/include/uapi/asm-generic/siginfo.h
+++ b/include/uapi/asm-generic/siginfo.h
@@ -91,7 +91,10 @@ union __sifields {
 				__u32 _pkey;
 			} _addr_pkey;
 			/* used when si_code=TRAP_PERF */
-			unsigned long _perf;
+			struct {
+				unsigned long _data;
+				__u32 _type;
+			} _perf;
 		};
 	} _sigfault;
 
@@ -154,7 +157,8 @@ typedef struct siginfo {
 #define si_lower	_sifields._sigfault._addr_bnd._lower
 #define si_upper	_sifields._sigfault._addr_bnd._upper
 #define si_pkey		_sifields._sigfault._addr_pkey._pkey
-#define si_perf		_sifields._sigfault._perf
+#define si_perf_data	_sifields._sigfault._perf._data
+#define si_perf_type	_sifields._sigfault._perf._type
 #define si_band		_sifields._sigpoll._band
 #define si_fd		_sifields._sigpoll._fd
 #define si_call_addr	_sifields._sigsys._call_addr
diff --git a/include/uapi/linux/perf_event.h b/include/uapi/linux/perf_event.h
index e54e639248c8..7b14753b3d38 100644
--- a/include/uapi/linux/perf_event.h
+++ b/include/uapi/linux/perf_event.h
@@ -464,7 +464,7 @@ struct perf_event_attr {
 
 	/*
 	 * User provided data if sigtrap=1, passed back to user via
-	 * siginfo_t::si_perf, e.g. to permit user to identify the event.
+	 * siginfo_t::si_perf_data, e.g. to permit user to identify the event.
 	 */
 	__u64	sig_data;
 };
diff --git a/include/uapi/linux/signalfd.h b/include/uapi/linux/signalfd.h
index 7e333042c7e3..e78dddf433fc 100644
--- a/include/uapi/linux/signalfd.h
+++ b/include/uapi/linux/signalfd.h
@@ -39,8 +39,8 @@ struct signalfd_siginfo {
 	__s32 ssi_syscall;
 	__u64 ssi_call_addr;
 	__u32 ssi_arch;
-	__u32 __pad3;
-	__u64 ssi_perf;
+	__u32 ssi_perf_type;
+	__u64 ssi_perf_data;
 
 	/*
 	 * Pad strcture to 128 bytes. Remember to update the
diff --git a/kernel/signal.c b/kernel/signal.c
index 3a18d13c39b2..dca53515ae3f 100644
--- a/kernel/signal.c
+++ b/kernel/signal.c
@@ -1768,11 +1768,13 @@ int force_sig_perf(void __user *addr, u32 type, u64 sig_data)
 	struct kernel_siginfo info;
 
 	clear_siginfo(&info);
-	info.si_signo = SIGTRAP;
-	info.si_errno = type;
-	info.si_code  = TRAP_PERF;
-	info.si_addr  = addr;
-	info.si_perf  = sig_data;
+	info.si_signo     = SIGTRAP;
+	info.si_errno     = 0;
+	info.si_code      = TRAP_PERF;
+	info.si_addr      = addr;
+	info.si_perf_data = sig_data;
+	info.si_perf_type = type;
+
 	return force_sig_info(&info);
 }
 
@@ -3356,7 +3358,8 @@ void copy_siginfo_to_external32(struct compat_siginfo *to,
 		break;
 	case SIL_PERF_EVENT:
 		to->si_addr = ptr_to_compat(from->si_addr);
-		to->si_perf = from->si_perf;
+		to->si_perf_data = from->si_perf_data;
+		to->si_perf_type = from->si_perf_type;
 		break;
 	case SIL_CHLD:
 		to->si_pid = from->si_pid;
@@ -3432,7 +3435,8 @@ static int post_copy_siginfo_from_user32(kernel_siginfo_t *to,
 		break;
 	case SIL_PERF_EVENT:
 		to->si_addr = compat_ptr(from->si_addr);
-		to->si_perf = from->si_perf;
+		to->si_perf_data = from->si_perf_data;
+		to->si_perf_type = from->si_perf_type;
 		break;
 	case SIL_CHLD:
 		to->si_pid    = from->si_pid;
@@ -4615,7 +4619,8 @@ static inline void siginfo_buildtime_checks(void)
 	CHECK_OFFSET(si_lower);
 	CHECK_OFFSET(si_upper);
 	CHECK_OFFSET(si_pkey);
-	CHECK_OFFSET(si_perf);
+	CHECK_OFFSET(si_perf_data);
+	CHECK_OFFSET(si_perf_type);
 
 	/* sigpoll */
 	CHECK_OFFSET(si_band);
diff --git a/tools/testing/selftests/perf_events/sigtrap_threads.c b/tools/testing/selftests/perf_events/sigtrap_threads.c
index 78ddf5e11625..8e83cf91513a 100644
--- a/tools/testing/selftests/perf_events/sigtrap_threads.c
+++ b/tools/testing/selftests/perf_events/sigtrap_threads.c
@@ -43,7 +43,7 @@ static struct {
 	siginfo_t first_siginfo;	/* First observed siginfo_t. */
 } ctx;
 
-/* Unique value to check si_perf is correctly set from perf_event_attr::sig_data. */
+/* Unique value to check si_perf_data is correctly set from perf_event_attr::sig_data. */
 #define TEST_SIG_DATA(addr) (~(unsigned long)(addr))
 
 static struct perf_event_attr make_event_attr(bool enabled, volatile void *addr)
@@ -164,8 +164,8 @@ TEST_F(sigtrap_threads, enable_event)
 	EXPECT_EQ(ctx.signal_count, NUM_THREADS);
 	EXPECT_EQ(ctx.tids_want_signal, 0);
 	EXPECT_EQ(ctx.first_siginfo.si_addr, &ctx.iterate_on);
-	EXPECT_EQ(ctx.first_siginfo.si_errno, PERF_TYPE_BREAKPOINT);
-	EXPECT_EQ(ctx.first_siginfo.si_perf, TEST_SIG_DATA(&ctx.iterate_on));
+	EXPECT_EQ(ctx.first_siginfo.si_perf_type, PERF_TYPE_BREAKPOINT);
+	EXPECT_EQ(ctx.first_siginfo.si_perf_data, TEST_SIG_DATA(&ctx.iterate_on));
 
 	/* Check enabled for parent. */
 	ctx.iterate_on = 0;
@@ -183,8 +183,8 @@ TEST_F(sigtrap_threads, modify_and_enable_event)
 	EXPECT_EQ(ctx.signal_count, NUM_THREADS);
 	EXPECT_EQ(ctx.tids_want_signal, 0);
 	EXPECT_EQ(ctx.first_siginfo.si_addr, &ctx.iterate_on);
-	EXPECT_EQ(ctx.first_siginfo.si_errno, PERF_TYPE_BREAKPOINT);
-	EXPECT_EQ(ctx.first_siginfo.si_perf, TEST_SIG_DATA(&ctx.iterate_on));
+	EXPECT_EQ(ctx.first_siginfo.si_perf_type, PERF_TYPE_BREAKPOINT);
+	EXPECT_EQ(ctx.first_siginfo.si_perf_data, TEST_SIG_DATA(&ctx.iterate_on));
 
 	/* Check enabled for parent. */
 	ctx.iterate_on = 0;
@@ -203,8 +203,8 @@ TEST_F(sigtrap_threads, signal_stress)
 	EXPECT_EQ(ctx.signal_count, NUM_THREADS * ctx.iterate_on);
 	EXPECT_EQ(ctx.tids_want_signal, 0);
 	EXPECT_EQ(ctx.first_siginfo.si_addr, &ctx.iterate_on);
-	EXPECT_EQ(ctx.first_siginfo.si_errno, PERF_TYPE_BREAKPOINT);
-	EXPECT_EQ(ctx.first_siginfo.si_perf, TEST_SIG_DATA(&ctx.iterate_on));
+	EXPECT_EQ(ctx.first_siginfo.si_perf_type, PERF_TYPE_BREAKPOINT);
+	EXPECT_EQ(ctx.first_siginfo.si_perf_data, TEST_SIG_DATA(&ctx.iterate_on));
 }
 
 TEST_HARNESS_MAIN
-- 
2.30.1

[PATCH v4 5/5] signalfd: Remove SIL_PERF_EVENT fields from signalfd_siginfo

[Eric W. Beiderman]

From: "Eric W. Biederman" <ebiederm@xmission.com>

With the addition of ssi_perf_data and ssi_perf_type struct signalfd_siginfo
is dangerously close to running out of space.  All that remains is just
enough space for two additional 64bit fields.  A practice of adding all
possible siginfo_t fields into struct singalfd_siginfo can not be supported
as adding the missing fields ssi_lower, ssi_upper, and ssi_pkey would
require two 64bit fields and one 32bit fields.  In practice the fields
ssi_perf_data and ssi_perf_type can never be used by signalfd as the signal
that generates them always delivers them synchronously to the thread that
triggers them.

Therefore until someone actually needs the fields ssi_perf_data and
ssi_perf_type in signalfd_siginfo remove them.  This leaves a bit more room
for future expansion.

v1: https://lkml.kernel.org/r/20210503203814.25487-12-ebiederm@xmission.com
v2: https://lkml.kernel.org/r/20210505141101.11519-12-ebiederm@xmission.com
Reviewed-by: Marco Elver <elver@google.com>
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
---
 fs/signalfd.c                 | 16 ++++++----------
 include/uapi/linux/signalfd.h |  4 +---
 2 files changed, 7 insertions(+), 13 deletions(-)

diff --git a/fs/signalfd.c b/fs/signalfd.c
index 373df2f12415..167b5889db4b 100644
--- a/fs/signalfd.c
+++ b/fs/signalfd.c
@@ -114,12 +114,13 @@ static int signalfd_copyinfo(struct signalfd_siginfo __user *uinfo,
 		break;
 	case SIL_FAULT_BNDERR:
 	case SIL_FAULT_PKUERR:
+	case SIL_PERF_EVENT:
 		/*
-		 * Fall through to the SIL_FAULT case.  Both SIL_FAULT_BNDERR
-		 * and SIL_FAULT_PKUERR are only generated by faults that
-		 * deliver them synchronously to userspace.  In case someone
-		 * injects one of these signals and signalfd catches it treat
-		 * it as SIL_FAULT.
+		 * Fall through to the SIL_FAULT case.  SIL_FAULT_BNDERR,
+		 * SIL_FAULT_PKUERR, and SIL_PERF_EVENT are only
+		 * generated by faults that deliver them synchronously to
+		 * userspace.  In case someone injects one of these signals
+		 * and signalfd catches it treat it as SIL_FAULT.
 		 */
 	case SIL_FAULT:
 		new.ssi_addr = (long) kinfo->si_addr;
@@ -132,11 +133,6 @@ static int signalfd_copyinfo(struct signalfd_siginfo __user *uinfo,
 		new.ssi_addr = (long) kinfo->si_addr;
 		new.ssi_addr_lsb = (short) kinfo->si_addr_lsb;
 		break;
-	case SIL_PERF_EVENT:
-		new.ssi_addr = (long) kinfo->si_addr;
-		new.ssi_perf_type = kinfo->si_perf_type;
-		new.ssi_perf_data = kinfo->si_perf_data;
-		break;
 	case SIL_CHLD:
 		new.ssi_pid    = kinfo->si_pid;
 		new.ssi_uid    = kinfo->si_uid;
diff --git a/include/uapi/linux/signalfd.h b/include/uapi/linux/signalfd.h
index e78dddf433fc..83429a05b698 100644
--- a/include/uapi/linux/signalfd.h
+++ b/include/uapi/linux/signalfd.h
@@ -39,8 +39,6 @@ struct signalfd_siginfo {
 	__s32 ssi_syscall;
 	__u64 ssi_call_addr;
 	__u32 ssi_arch;
-	__u32 ssi_perf_type;
-	__u64 ssi_perf_data;
 
 	/*
 	 * Pad strcture to 128 bytes. Remember to update the
@@ -51,7 +49,7 @@ struct signalfd_siginfo {
 	 * comes out of a read(2) and we really don't want to have
 	 * a compat on read(2).
 	 */
-	__u8 __pad[16];
+	__u8 __pad[28];
 };
 
 
-- 
2.30.1

Re: [PATCH v4 0/5] siginfo: ABI fixes for TRAP_PERF

[Marco Elver]

On Mon, 17 May 2021 at 21:58, Eric W. Biederman <ebiederm@xmission.com> wrote:
>
> During the merge window an issue with si_perf and the siginfo ABI came
> up.  The alpha and sparc siginfo structure layout had changed with the
> addition of SIGTRAP TRAP_PERF and the new field si_perf.
>
> The reason only alpha and sparc were affected is that they are the
> only architectures that use si_trapno.
>
> Looking deeper it was discovered that si_trapno is used for only
> a few select signals on alpha and sparc, and that none of the
> other _sigfault fields past si_addr are used at all.  Which means
> technically no regression on alpha and sparc.
>
> While the alignment concerns might be dismissed the abuse of
> si_errno by SIGTRAP TRAP_PERF does have the potential to cause
> regressions in existing userspace.
>
> While we still have time before userspace starts using and depending on
> the new definition siginfo for SIGTRAP TRAP_PERF this set of changes
> cleans up siginfo_t.
>
> - The si_trapno field is demoted from magic alpha and sparc status and
>   made an ordinary union member of the _sigfault member of siginfo_t.
>   Without moving it of course.
>
> - si_perf is replaced with si_perf_data and si_perf_type ending the
>   abuse of si_errno.
>
> - Unnecessary additions to signalfd_siginfo are removed.
>
> v3: https://lkml.kernel.org/r/m1tuni8ano.fsf_-_@fess.ebiederm.org
> v2: https://lkml.kernel.org/r/m14kfjh8et.fsf_-_@fess.ebiederm.org
> v1: https://lkml.kernel.org/r/m1zgxfs7zq.fsf_-_@fess.ebiederm.org
>
> This version drops the tests and fine grained handling of si_trapno
> on alpha and sparc (replaced assuming si_trapno is valid for
> all but the faults that defined different data).

And just to clarify, the rest of the series (including static-asserts)
for the next merge-window will be sent once this series is all sorted,
correct?

> Eric W. Biederman (5):
>       siginfo: Move si_trapno inside the union inside _si_fault
>       signal: Implement SIL_FAULT_TRAPNO
>       signal: Factor force_sig_perf out of perf_sigtrap
>       signal: Deliver all of the siginfo perf data in _perf
>       signalfd: Remove SIL_PERF_EVENT fields from signalfd_siginfo

Looks good, thank you! I build-tested (defconfig -- x86_64, i386, arm,
arm64, m68k, sparc, alpha) this series together with a local patch to
pull in the static asserts from v3. Also re-ran perf_events kselftests
on x86_64 (native and 32bit compat).

Thanks,
-- Marco

Re: [PATCH v4 0/5] siginfo: ABI fixes for TRAP_PERF

[Eric W. Biederman]

Marco Elver <elver@google.com> writes:

> On Mon, 17 May 2021 at 21:58, Eric W. Biederman <ebiederm@xmission.com> wrote:
>>
>> During the merge window an issue with si_perf and the siginfo ABI came
>> up.  The alpha and sparc siginfo structure layout had changed with the
>> addition of SIGTRAP TRAP_PERF and the new field si_perf.
>>
>> The reason only alpha and sparc were affected is that they are the
>> only architectures that use si_trapno.
>>
>> Looking deeper it was discovered that si_trapno is used for only
>> a few select signals on alpha and sparc, and that none of the
>> other _sigfault fields past si_addr are used at all.  Which means
>> technically no regression on alpha and sparc.
>>
>> While the alignment concerns might be dismissed the abuse of
>> si_errno by SIGTRAP TRAP_PERF does have the potential to cause
>> regressions in existing userspace.
>>
>> While we still have time before userspace starts using and depending on
>> the new definition siginfo for SIGTRAP TRAP_PERF this set of changes
>> cleans up siginfo_t.
>>
>> - The si_trapno field is demoted from magic alpha and sparc status and
>>   made an ordinary union member of the _sigfault member of siginfo_t.
>>   Without moving it of course.
>>
>> - si_perf is replaced with si_perf_data and si_perf_type ending the
>>   abuse of si_errno.
>>
>> - Unnecessary additions to signalfd_siginfo are removed.
>>
>> v3: https://lkml.kernel.org/r/m1tuni8ano.fsf_-_@fess.ebiederm.org
>> v2: https://lkml.kernel.org/r/m14kfjh8et.fsf_-_@fess.ebiederm.org
>> v1: https://lkml.kernel.org/r/m1zgxfs7zq.fsf_-_@fess.ebiederm.org
>>
>> This version drops the tests and fine grained handling of si_trapno
>> on alpha and sparc (replaced assuming si_trapno is valid for
>> all but the faults that defined different data).
>
> And just to clarify, the rest of the series (including static-asserts)
> for the next merge-window will be sent once this series is all sorted,
> correct?

That is the plan.

I really wonder about alphas use of si_trapno, and alphas use send_sig
instead of force_sig.  It could be worth looking into those as it
has the potential to simplify the code.

>> Eric W. Biederman (5):
>>       siginfo: Move si_trapno inside the union inside _si_fault
>>       signal: Implement SIL_FAULT_TRAPNO
>>       signal: Factor force_sig_perf out of perf_sigtrap
>>       signal: Deliver all of the siginfo perf data in _perf
>>       signalfd: Remove SIL_PERF_EVENT fields from signalfd_siginfo
>
> Looks good, thank you! I build-tested (defconfig -- x86_64, i386, arm,
> arm64, m68k, sparc, alpha) this series together with a local patch to
> pull in the static asserts from v3. Also re-ran perf_events kselftests
> on x86_64 (native and 32bit compat).

Thanks,

Can I have your Tested-by?

Eric

Re: [PATCH v4 0/5] siginfo: ABI fixes for TRAP_PERF

[Marco Elver]

On Tue, 18 May 2021 at 05:47, Eric W. Biederman <ebiederm@xmission.com> wrote:
>
> Marco Elver <elver@google.com> writes:
>
> > On Mon, 17 May 2021 at 21:58, Eric W. Biederman <ebiederm@xmission.com> wrote:
> >>
> >> During the merge window an issue with si_perf and the siginfo ABI came
> >> up.  The alpha and sparc siginfo structure layout had changed with the
> >> addition of SIGTRAP TRAP_PERF and the new field si_perf.
> >>
> >> The reason only alpha and sparc were affected is that they are the
> >> only architectures that use si_trapno.
> >>
> >> Looking deeper it was discovered that si_trapno is used for only
> >> a few select signals on alpha and sparc, and that none of the
> >> other _sigfault fields past si_addr are used at all.  Which means
> >> technically no regression on alpha and sparc.
> >>
> >> While the alignment concerns might be dismissed the abuse of
> >> si_errno by SIGTRAP TRAP_PERF does have the potential to cause
> >> regressions in existing userspace.
> >>
> >> While we still have time before userspace starts using and depending on
> >> the new definition siginfo for SIGTRAP TRAP_PERF this set of changes
> >> cleans up siginfo_t.
> >>
> >> - The si_trapno field is demoted from magic alpha and sparc status and
> >>   made an ordinary union member of the _sigfault member of siginfo_t.
> >>   Without moving it of course.
> >>
> >> - si_perf is replaced with si_perf_data and si_perf_type ending the
> >>   abuse of si_errno.
> >>
> >> - Unnecessary additions to signalfd_siginfo are removed.
> >>
> >> v3: https://lkml.kernel.org/r/m1tuni8ano.fsf_-_@fess.ebiederm.org
> >> v2: https://lkml.kernel.org/r/m14kfjh8et.fsf_-_@fess.ebiederm.org
> >> v1: https://lkml.kernel.org/r/m1zgxfs7zq.fsf_-_@fess.ebiederm.org
> >>
> >> This version drops the tests and fine grained handling of si_trapno
> >> on alpha and sparc (replaced assuming si_trapno is valid for
> >> all but the faults that defined different data).
> >
> > And just to clarify, the rest of the series (including static-asserts)
> > for the next merge-window will be sent once this series is all sorted,
> > correct?
>
> That is the plan.
>
> I really wonder about alphas use of si_trapno, and alphas use send_sig
> instead of force_sig.  It could be worth looking into those as it
> has the potential to simplify the code.
>
> >> Eric W. Biederman (5):
> >>       siginfo: Move si_trapno inside the union inside _si_fault
> >>       signal: Implement SIL_FAULT_TRAPNO
> >>       signal: Factor force_sig_perf out of perf_sigtrap
> >>       signal: Deliver all of the siginfo perf data in _perf
> >>       signalfd: Remove SIL_PERF_EVENT fields from signalfd_siginfo
> >
> > Looks good, thank you! I build-tested (defconfig -- x86_64, i386, arm,
> > arm64, m68k, sparc, alpha) this series together with a local patch to
> > pull in the static asserts from v3. Also re-ran perf_events kselftests
> > on x86_64 (native and 32bit compat).
>
> Thanks,
>
> Can I have your Tested-by?

Of course,

  Tested-by: Marco Elver <elver@google.com>

Thanks,
-- Marco

Re: [RFC][PATCH 0/3] signal: Move si_trapno into the _si_fault union

[Marco Elver]

On Sat, 1 May 2021 at 02:37, Marco Elver <elver@google.com> wrote:
> On Sat, 1 May 2021 at 01:48, Eric W. Biederman <ebiederm@xmission.com> wrote:
> >
> > Well with 7 patches instead of 3 that was a little more than I thought
> > I was going to send.
> >
> > However that does demonstrate what I am thinking, and I think most of
> > the changes are reasonable at this point.
> >
> > I am very curious how synchronous this all is, because if this code
> > is truly synchronous updating signalfd to handle this class of signal
> > doesn't really make sense.

Just a note on this: the reason for adding signalfd support was based
on the comment at SIL_FAULT_PKUERR:

>                 /*
>                   * Fall through to the SIL_FAULT case.  Both SIL_FAULT_BNDERR
>                   * and SIL_FAULT_PKUERR are only generated by faults that
>                   * deliver them synchronously to userspace.  In case someone
>                   * injects one of these signals and signalfd catches it treat
>                   * it as SIL_FAULT.
>                   */

The same would hold for SIL_FAULT_PERF_EVENT, where somebody injects
(re-injects perhaps?) such an event. But otherwise, yes,
non-synchronous handling of SIGTRAP/TRAP_PERF is pretty useless for
almost all usecases I can think of.

Thanks,
-- Marco

[PATCH 0/6] Final si_trapno bits

[Eric W. Biederman]

As a part of a fix for the ABI of the newly added SIGTRAP TRAP_PERF a
si_trapno was reduced to an ordinary extention of the _sigfault case
of struct siginfo.

When Linus saw the complete set of changes come in as a fix he requested
that the set of changes be trimmed down to just what was necessary to
fix the SIGTRAP TRAP_PERF ABI.

I had intended to get the rest of the changes into the merge window for
v5.14 but I dropped the ball.

I have made the changes to stop using __ARCH_SI_TRAPNO be per
architecture so they are easier to review.  In doing so I found one
place on alpha where I used send_sig_fault instead of
send_sig_fault_trapno(... si_trapno = 0).  That would not have changed
the userspace behavior but it did make the kernel code less clear.

My rule in these patches is everywhere that siginfo layout calls
for SIL_FAULT_TRAPNO the code uses either force_sig_fault_trapno
or send_sig_fault_trapno.

And of course I have rebased and compile tested Marco's compile time
assert patches.

Eric


Eric W. Biederman (3):
      signal/sparc: si_trapno is only used with SIGILL ILL_ILLTRP
      signal/alpha: si_trapno is only used with SIGFPE and SIGTRAP TRAP_UNK
      signal: Remove the generic __ARCH_SI_TRAPNO support

Marco Elver (3):
      sparc64: Add compile-time asserts for siginfo_t offsets
      arm: Add compile-time asserts for siginfo_t offsets
      arm64: Add compile-time asserts for siginfo_t offsets

 arch/alpha/include/uapi/asm/siginfo.h |  2 --
 arch/alpha/kernel/osf_sys.c           |  2 +-
 arch/alpha/kernel/signal.c            |  4 +--
 arch/alpha/kernel/traps.c             | 26 +++++++++---------
 arch/alpha/mm/fault.c                 |  4 +--
 arch/arm/kernel/signal.c              | 37 +++++++++++++++++++++++++
 arch/arm64/kernel/signal.c            | 37 +++++++++++++++++++++++++
 arch/arm64/kernel/signal32.c          | 37 +++++++++++++++++++++++++
 arch/mips/include/uapi/asm/siginfo.h  |  2 --
 arch/sparc/include/uapi/asm/siginfo.h |  3 --
 arch/sparc/kernel/process_64.c        |  2 +-
 arch/sparc/kernel/signal32.c          | 35 +++++++++++++++++++++++
 arch/sparc/kernel/signal_64.c         | 34 +++++++++++++++++++++++
 arch/sparc/kernel/sys_sparc_32.c      |  2 +-
 arch/sparc/kernel/sys_sparc_64.c      |  2 +-
 arch/sparc/kernel/traps_32.c          | 22 +++++++--------
 arch/sparc/kernel/traps_64.c          | 44 +++++++++++++----------------
 arch/sparc/kernel/unaligned_32.c      |  2 +-
 arch/sparc/mm/fault_32.c              |  2 +-
 arch/sparc/mm/fault_64.c              |  2 +-
 include/linux/sched/signal.h          | 11 ++------
 kernel/signal.c                       | 52 ++++++++++++++++++++++++++---------
 22 files changed, 276 insertions(+), 88 deletions(-)

[PATCH 1/6] sparc64: Add compile-time asserts for siginfo_t offsets

[Eric W. Biederman]

From: Marco Elver <elver@google.com>

To help catch ABI breaks at compile-time, add compile-time assertions to
verify the siginfo_t layout. Unlike other architectures, sparc64 is
special, because it is one of few architectures requiring si_trapno.
ABI breaks around that field would only be caught here.

Link: https://lkml.kernel.org/r/m11rat9f85.fsf@fess.ebiederm.org
Link: https://lkml.kernel.org/r/20210429190734.624918-1-elver@google.com
Link: https://lkml.kernel.org/r/20210505141101.11519-1-ebiederm@xmission.com
Suggested-by: Eric W. Biederman <ebiederm@xmission.com>
Acked-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Marco Elver <elver@google.com>
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
---
 arch/sparc/kernel/signal32.c  | 35 +++++++++++++++++++++++++++++++++++
 arch/sparc/kernel/signal_64.c | 34 ++++++++++++++++++++++++++++++++++
 2 files changed, 69 insertions(+)

diff --git a/arch/sparc/kernel/signal32.c b/arch/sparc/kernel/signal32.c
index e9695a06492f..65fd26ae9d25 100644
--- a/arch/sparc/kernel/signal32.c
+++ b/arch/sparc/kernel/signal32.c
@@ -745,3 +745,38 @@ asmlinkage int do_sys32_sigstack(u32 u_ssptr, u32 u_ossptr, unsigned long sp)
 out:
 	return ret;
 }
+
+/*
+ * Compile-time assertions for siginfo_t offsets. Check NSIG* as well, as
+ * changes likely come with new fields that should be added below.
+ */
+static_assert(NSIGILL	== 11);
+static_assert(NSIGFPE	== 15);
+static_assert(NSIGSEGV	== 9);
+static_assert(NSIGBUS	== 5);
+static_assert(NSIGTRAP	== 6);
+static_assert(NSIGCHLD	== 6);
+static_assert(NSIGSYS	== 2);
+static_assert(offsetof(compat_siginfo_t, si_signo)	== 0x00);
+static_assert(offsetof(compat_siginfo_t, si_errno)	== 0x04);
+static_assert(offsetof(compat_siginfo_t, si_code)	== 0x08);
+static_assert(offsetof(compat_siginfo_t, si_pid)	== 0x0c);
+static_assert(offsetof(compat_siginfo_t, si_uid)	== 0x10);
+static_assert(offsetof(compat_siginfo_t, si_tid)	== 0x0c);
+static_assert(offsetof(compat_siginfo_t, si_overrun)	== 0x10);
+static_assert(offsetof(compat_siginfo_t, si_status)	== 0x14);
+static_assert(offsetof(compat_siginfo_t, si_utime)	== 0x18);
+static_assert(offsetof(compat_siginfo_t, si_stime)	== 0x1c);
+static_assert(offsetof(compat_siginfo_t, si_value)	== 0x14);
+static_assert(offsetof(compat_siginfo_t, si_int)	== 0x14);
+static_assert(offsetof(compat_siginfo_t, si_ptr)	== 0x14);
+static_assert(offsetof(compat_siginfo_t, si_addr)	== 0x0c);
+static_assert(offsetof(compat_siginfo_t, si_trapno)	== 0x10);
+static_assert(offsetof(compat_siginfo_t, si_addr_lsb)	== 0x10);
+static_assert(offsetof(compat_siginfo_t, si_lower)	== 0x14);
+static_assert(offsetof(compat_siginfo_t, si_upper)	== 0x18);
+static_assert(offsetof(compat_siginfo_t, si_pkey)	== 0x14);
+static_assert(offsetof(compat_siginfo_t, si_perf_data)	== 0x10);
+static_assert(offsetof(compat_siginfo_t, si_perf_type)	== 0x14);
+static_assert(offsetof(compat_siginfo_t, si_band)	== 0x0c);
+static_assert(offsetof(compat_siginfo_t, si_fd)		== 0x10);
diff --git a/arch/sparc/kernel/signal_64.c b/arch/sparc/kernel/signal_64.c
index a0eec62c825d..a58e0cc45d24 100644
--- a/arch/sparc/kernel/signal_64.c
+++ b/arch/sparc/kernel/signal_64.c
@@ -556,3 +556,37 @@ void do_notify_resume(struct pt_regs *regs, unsigned long orig_i0, unsigned long
 	user_enter();
 }
 
+/*
+ * Compile-time assertions for siginfo_t offsets. Check NSIG* as well, as
+ * changes likely come with new fields that should be added below.
+ */
+static_assert(NSIGILL	== 11);
+static_assert(NSIGFPE	== 15);
+static_assert(NSIGSEGV	== 9);
+static_assert(NSIGBUS	== 5);
+static_assert(NSIGTRAP	== 6);
+static_assert(NSIGCHLD	== 6);
+static_assert(NSIGSYS	== 2);
+static_assert(offsetof(siginfo_t, si_signo)	== 0x00);
+static_assert(offsetof(siginfo_t, si_errno)	== 0x04);
+static_assert(offsetof(siginfo_t, si_code)	== 0x08);
+static_assert(offsetof(siginfo_t, si_pid)	== 0x10);
+static_assert(offsetof(siginfo_t, si_uid)	== 0x14);
+static_assert(offsetof(siginfo_t, si_tid)	== 0x10);
+static_assert(offsetof(siginfo_t, si_overrun)	== 0x14);
+static_assert(offsetof(siginfo_t, si_status)	== 0x18);
+static_assert(offsetof(siginfo_t, si_utime)	== 0x20);
+static_assert(offsetof(siginfo_t, si_stime)	== 0x28);
+static_assert(offsetof(siginfo_t, si_value)	== 0x18);
+static_assert(offsetof(siginfo_t, si_int)	== 0x18);
+static_assert(offsetof(siginfo_t, si_ptr)	== 0x18);
+static_assert(offsetof(siginfo_t, si_addr)	== 0x10);
+static_assert(offsetof(siginfo_t, si_trapno)	== 0x18);
+static_assert(offsetof(siginfo_t, si_addr_lsb)	== 0x18);
+static_assert(offsetof(siginfo_t, si_lower)	== 0x20);
+static_assert(offsetof(siginfo_t, si_upper)	== 0x28);
+static_assert(offsetof(siginfo_t, si_pkey)	== 0x20);
+static_assert(offsetof(siginfo_t, si_perf_data)	== 0x18);
+static_assert(offsetof(siginfo_t, si_perf_type)	== 0x20);
+static_assert(offsetof(siginfo_t, si_band)	== 0x10);
+static_assert(offsetof(siginfo_t, si_fd)	== 0x14);
-- 
2.20.1

[PATCH 2/6] arm: Add compile-time asserts for siginfo_t offsets

[Eric W. Biederman]

From: Marco Elver <elver@google.com>

To help catch ABI breaks at compile-time, add compile-time assertions to
verify the siginfo_t layout.

This could have caught that we cannot portably add 64-bit integers to
siginfo_t on 32-bit architectures like Arm before reaching -next:
https://lkml.kernel.org/r/20210422191823.79012-1-elver@google.com

Link: https://lkml.kernel.org/r/20210429190734.624918-2-elver@google.com
Link: https://lkml.kernel.org/r/20210505141101.11519-2-ebiederm@xmission.com
Signed-off-by: Marco Elver <elver@google.com>
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
---
 arch/arm/kernel/signal.c | 37 +++++++++++++++++++++++++++++++++++++
 1 file changed, 37 insertions(+)

diff --git a/arch/arm/kernel/signal.c b/arch/arm/kernel/signal.c
index a3a38d0a4c85..7ef453e8a96f 100644
--- a/arch/arm/kernel/signal.c
+++ b/arch/arm/kernel/signal.c
@@ -725,3 +725,40 @@ asmlinkage void do_rseq_syscall(struct pt_regs *regs)
 	rseq_syscall(regs);
 }
 #endif
+
+/*
+ * Compile-time assertions for siginfo_t offsets. Check NSIG* as well, as
+ * changes likely come with new fields that should be added below.
+ */
+static_assert(NSIGILL	== 11);
+static_assert(NSIGFPE	== 15);
+static_assert(NSIGSEGV	== 9);
+static_assert(NSIGBUS	== 5);
+static_assert(NSIGTRAP	== 6);
+static_assert(NSIGCHLD	== 6);
+static_assert(NSIGSYS	== 2);
+static_assert(offsetof(siginfo_t, si_signo)	== 0x00);
+static_assert(offsetof(siginfo_t, si_errno)	== 0x04);
+static_assert(offsetof(siginfo_t, si_code)	== 0x08);
+static_assert(offsetof(siginfo_t, si_pid)	== 0x0c);
+static_assert(offsetof(siginfo_t, si_uid)	== 0x10);
+static_assert(offsetof(siginfo_t, si_tid)	== 0x0c);
+static_assert(offsetof(siginfo_t, si_overrun)	== 0x10);
+static_assert(offsetof(siginfo_t, si_status)	== 0x14);
+static_assert(offsetof(siginfo_t, si_utime)	== 0x18);
+static_assert(offsetof(siginfo_t, si_stime)	== 0x1c);
+static_assert(offsetof(siginfo_t, si_value)	== 0x14);
+static_assert(offsetof(siginfo_t, si_int)	== 0x14);
+static_assert(offsetof(siginfo_t, si_ptr)	== 0x14);
+static_assert(offsetof(siginfo_t, si_addr)	== 0x0c);
+static_assert(offsetof(siginfo_t, si_addr_lsb)	== 0x10);
+static_assert(offsetof(siginfo_t, si_lower)	== 0x14);
+static_assert(offsetof(siginfo_t, si_upper)	== 0x18);
+static_assert(offsetof(siginfo_t, si_pkey)	== 0x14);
+static_assert(offsetof(siginfo_t, si_perf_data)	== 0x10);
+static_assert(offsetof(siginfo_t, si_perf_type)	== 0x14);
+static_assert(offsetof(siginfo_t, si_band)	== 0x0c);
+static_assert(offsetof(siginfo_t, si_fd)	== 0x10);
+static_assert(offsetof(siginfo_t, si_call_addr)	== 0x0c);
+static_assert(offsetof(siginfo_t, si_syscall)	== 0x10);
+static_assert(offsetof(siginfo_t, si_arch)	== 0x14);
-- 
2.20.1

[PATCH 3/6] arm64: Add compile-time asserts for siginfo_t offsets

[Eric W. Biederman]

From: Marco Elver <elver@google.com>

To help catch ABI breaks at compile-time, add compile-time assertions to
verify the siginfo_t layout.

Link: https://lkml.kernel.org/r/20210505141101.11519-3-ebiederm@xmission.com
Link: https://lkml.kernel.org/r/20210429190734.624918-3-elver@google.com
Signed-off-by: Marco Elver <elver@google.com>
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
---
 arch/arm64/kernel/signal.c   | 37 ++++++++++++++++++++++++++++++++++++
 arch/arm64/kernel/signal32.c | 37 ++++++++++++++++++++++++++++++++++++
 2 files changed, 74 insertions(+)

diff --git a/arch/arm64/kernel/signal.c b/arch/arm64/kernel/signal.c
index f8192f4ae0b8..4413b6a4e32a 100644
--- a/arch/arm64/kernel/signal.c
+++ b/arch/arm64/kernel/signal.c
@@ -999,3 +999,40 @@ void __init minsigstksz_setup(void)
 		round_up(sizeof(struct frame_record), 16) +
 		16; /* max alignment padding */
 }
+
+/*
+ * Compile-time assertions for siginfo_t offsets. Check NSIG* as well, as
+ * changes likely come with new fields that should be added below.
+ */
+static_assert(NSIGILL	== 11);
+static_assert(NSIGFPE	== 15);
+static_assert(NSIGSEGV	== 9);
+static_assert(NSIGBUS	== 5);
+static_assert(NSIGTRAP	== 6);
+static_assert(NSIGCHLD	== 6);
+static_assert(NSIGSYS	== 2);
+static_assert(offsetof(siginfo_t, si_signo)	== 0x00);
+static_assert(offsetof(siginfo_t, si_errno)	== 0x04);
+static_assert(offsetof(siginfo_t, si_code)	== 0x08);
+static_assert(offsetof(siginfo_t, si_pid)	== 0x10);
+static_assert(offsetof(siginfo_t, si_uid)	== 0x14);
+static_assert(offsetof(siginfo_t, si_tid)	== 0x10);
+static_assert(offsetof(siginfo_t, si_overrun)	== 0x14);
+static_assert(offsetof(siginfo_t, si_status)	== 0x18);
+static_assert(offsetof(siginfo_t, si_utime)	== 0x20);
+static_assert(offsetof(siginfo_t, si_stime)	== 0x28);
+static_assert(offsetof(siginfo_t, si_value)	== 0x18);
+static_assert(offsetof(siginfo_t, si_int)	== 0x18);
+static_assert(offsetof(siginfo_t, si_ptr)	== 0x18);
+static_assert(offsetof(siginfo_t, si_addr)	== 0x10);
+static_assert(offsetof(siginfo_t, si_addr_lsb)	== 0x18);
+static_assert(offsetof(siginfo_t, si_lower)	== 0x20);
+static_assert(offsetof(siginfo_t, si_upper)	== 0x28);
+static_assert(offsetof(siginfo_t, si_pkey)	== 0x20);
+static_assert(offsetof(siginfo_t, si_perf_data)	== 0x18);
+static_assert(offsetof(siginfo_t, si_perf_type)	== 0x20);
+static_assert(offsetof(siginfo_t, si_band)	== 0x10);
+static_assert(offsetof(siginfo_t, si_fd)	== 0x18);
+static_assert(offsetof(siginfo_t, si_call_addr)	== 0x10);
+static_assert(offsetof(siginfo_t, si_syscall)	== 0x18);
+static_assert(offsetof(siginfo_t, si_arch)	== 0x1c);
diff --git a/arch/arm64/kernel/signal32.c b/arch/arm64/kernel/signal32.c
index 2f507f565c48..ab1775216712 100644
--- a/arch/arm64/kernel/signal32.c
+++ b/arch/arm64/kernel/signal32.c
@@ -457,3 +457,40 @@ void compat_setup_restart_syscall(struct pt_regs *regs)
 {
        regs->regs[7] = __NR_compat_restart_syscall;
 }
+
+/*
+ * Compile-time assertions for siginfo_t offsets. Check NSIG* as well, as
+ * changes likely come with new fields that should be added below.
+ */
+static_assert(NSIGILL	== 11);
+static_assert(NSIGFPE	== 15);
+static_assert(NSIGSEGV	== 9);
+static_assert(NSIGBUS	== 5);
+static_assert(NSIGTRAP	== 6);
+static_assert(NSIGCHLD	== 6);
+static_assert(NSIGSYS	== 2);
+static_assert(offsetof(compat_siginfo_t, si_signo)	== 0x00);
+static_assert(offsetof(compat_siginfo_t, si_errno)	== 0x04);
+static_assert(offsetof(compat_siginfo_t, si_code)	== 0x08);
+static_assert(offsetof(compat_siginfo_t, si_pid)	== 0x0c);
+static_assert(offsetof(compat_siginfo_t, si_uid)	== 0x10);
+static_assert(offsetof(compat_siginfo_t, si_tid)	== 0x0c);
+static_assert(offsetof(compat_siginfo_t, si_overrun)	== 0x10);
+static_assert(offsetof(compat_siginfo_t, si_status)	== 0x14);
+static_assert(offsetof(compat_siginfo_t, si_utime)	== 0x18);
+static_assert(offsetof(compat_siginfo_t, si_stime)	== 0x1c);
+static_assert(offsetof(compat_siginfo_t, si_value)	== 0x14);
+static_assert(offsetof(compat_siginfo_t, si_int)	== 0x14);
+static_assert(offsetof(compat_siginfo_t, si_ptr)	== 0x14);
+static_assert(offsetof(compat_siginfo_t, si_addr)	== 0x0c);
+static_assert(offsetof(compat_siginfo_t, si_addr_lsb)	== 0x10);
+static_assert(offsetof(compat_siginfo_t, si_lower)	== 0x14);
+static_assert(offsetof(compat_siginfo_t, si_upper)	== 0x18);
+static_assert(offsetof(compat_siginfo_t, si_pkey)	== 0x14);
+static_assert(offsetof(compat_siginfo_t, si_perf_data)	== 0x10);
+static_assert(offsetof(compat_siginfo_t, si_perf_type)	== 0x14);
+static_assert(offsetof(compat_siginfo_t, si_band)	== 0x0c);
+static_assert(offsetof(compat_siginfo_t, si_fd)		== 0x10);
+static_assert(offsetof(compat_siginfo_t, si_call_addr)	== 0x0c);
+static_assert(offsetof(compat_siginfo_t, si_syscall)	== 0x10);
+static_assert(offsetof(compat_siginfo_t, si_arch)	== 0x14);
-- 
2.20.1

[PATCH 4/6] signal/sparc: si_trapno is only used with SIGILL ILL_ILLTRP

[Eric W. Biederman]

While reviewing the signal handlers on sparc it became clear that
si_trapno is only set to a non-zero value when sending SIGILL with
si_code ILL_ILLTRP.

Add force_sig_fault_trapno and send SIGILL ILL_ILLTRP with it.

Remove the define of __ARCH_SI_TRAPNO and remove the always zero
si_trapno parameter from send_sig_fault and force_sig_fault.

v1: https://lkml.kernel.org/r/m1eeers7q7.fsf_-_@fess.ebiederm.org
v2: https://lkml.kernel.org/r/20210505141101.11519-7-ebiederm@xmission.com
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
---
 arch/sparc/include/uapi/asm/siginfo.h |  3 --
 arch/sparc/kernel/process_64.c        |  2 +-
 arch/sparc/kernel/sys_sparc_32.c      |  2 +-
 arch/sparc/kernel/sys_sparc_64.c      |  2 +-
 arch/sparc/kernel/traps_32.c          | 22 +++++++-------
 arch/sparc/kernel/traps_64.c          | 44 ++++++++++++---------------
 arch/sparc/kernel/unaligned_32.c      |  2 +-
 arch/sparc/mm/fault_32.c              |  2 +-
 arch/sparc/mm/fault_64.c              |  2 +-
 include/linux/sched/signal.h          |  1 +
 kernel/signal.c                       | 19 ++++++++++++
 11 files changed, 56 insertions(+), 45 deletions(-)

diff --git a/arch/sparc/include/uapi/asm/siginfo.h b/arch/sparc/include/uapi/asm/siginfo.h
index 68bdde4c2a2e..0e7c27522aed 100644
--- a/arch/sparc/include/uapi/asm/siginfo.h
+++ b/arch/sparc/include/uapi/asm/siginfo.h
@@ -8,9 +8,6 @@
 
 #endif /* defined(__sparc__) && defined(__arch64__) */
 
-
-#define __ARCH_SI_TRAPNO
-
 #include <asm-generic/siginfo.h>
 
 
diff --git a/arch/sparc/kernel/process_64.c b/arch/sparc/kernel/process_64.c
index d33c58a58d4f..547b06b49ce3 100644
--- a/arch/sparc/kernel/process_64.c
+++ b/arch/sparc/kernel/process_64.c
@@ -518,7 +518,7 @@ void synchronize_user_stack(void)
 
 static void stack_unaligned(unsigned long sp)
 {
-	force_sig_fault(SIGBUS, BUS_ADRALN, (void __user *) sp, 0);
+	force_sig_fault(SIGBUS, BUS_ADRALN, (void __user *) sp);
 }
 
 static const char uwfault32[] = KERN_INFO \
diff --git a/arch/sparc/kernel/sys_sparc_32.c b/arch/sparc/kernel/sys_sparc_32.c
index be77538bc038..082a551897ed 100644
--- a/arch/sparc/kernel/sys_sparc_32.c
+++ b/arch/sparc/kernel/sys_sparc_32.c
@@ -151,7 +151,7 @@ sparc_breakpoint (struct pt_regs *regs)
 #ifdef DEBUG_SPARC_BREAKPOINT
         printk ("TRAP: Entering kernel PC=%x, nPC=%x\n", regs->pc, regs->npc);
 #endif
-	force_sig_fault(SIGTRAP, TRAP_BRKPT, (void __user *)regs->pc, 0);
+	force_sig_fault(SIGTRAP, TRAP_BRKPT, (void __user *)regs->pc);
 
 #ifdef DEBUG_SPARC_BREAKPOINT
 	printk ("TRAP: Returning to space: PC=%x nPC=%x\n", regs->pc, regs->npc);
diff --git a/arch/sparc/kernel/sys_sparc_64.c b/arch/sparc/kernel/sys_sparc_64.c
index 6b92fadb6ec7..1e9a9e016237 100644
--- a/arch/sparc/kernel/sys_sparc_64.c
+++ b/arch/sparc/kernel/sys_sparc_64.c
@@ -514,7 +514,7 @@ asmlinkage void sparc_breakpoint(struct pt_regs *regs)
 #ifdef DEBUG_SPARC_BREAKPOINT
         printk ("TRAP: Entering kernel PC=%lx, nPC=%lx\n", regs->tpc, regs->tnpc);
 #endif
-	force_sig_fault(SIGTRAP, TRAP_BRKPT, (void __user *)regs->tpc, 0);
+	force_sig_fault(SIGTRAP, TRAP_BRKPT, (void __user *)regs->tpc);
 #ifdef DEBUG_SPARC_BREAKPOINT
 	printk ("TRAP: Returning to space: PC=%lx nPC=%lx\n", regs->tpc, regs->tnpc);
 #endif
diff --git a/arch/sparc/kernel/traps_32.c b/arch/sparc/kernel/traps_32.c
index 247a0d9683b2..5630e5a395e0 100644
--- a/arch/sparc/kernel/traps_32.c
+++ b/arch/sparc/kernel/traps_32.c
@@ -102,8 +102,8 @@ void do_hw_interrupt(struct pt_regs *regs, unsigned long type)
 	if(regs->psr & PSR_PS)
 		die_if_kernel("Kernel bad trap", regs);
 
-	force_sig_fault(SIGILL, ILL_ILLTRP,
-			(void __user *)regs->pc, type - 0x80);
+	force_sig_fault_trapno(SIGILL, ILL_ILLTRP,
+			       (void __user *)regs->pc, type - 0x80);
 }
 
 void do_illegal_instruction(struct pt_regs *regs, unsigned long pc, unsigned long npc,
@@ -116,7 +116,7 @@ void do_illegal_instruction(struct pt_regs *regs, unsigned long pc, unsigned lon
 	       regs->pc, *(unsigned long *)regs->pc);
 #endif
 
-	send_sig_fault(SIGILL, ILL_ILLOPC, (void __user *)pc, 0, current);
+	send_sig_fault(SIGILL, ILL_ILLOPC, (void __user *)pc, current);
 }
 
 void do_priv_instruction(struct pt_regs *regs, unsigned long pc, unsigned long npc,
@@ -124,7 +124,7 @@ void do_priv_instruction(struct pt_regs *regs, unsigned long pc, unsigned long n
 {
 	if(psr & PSR_PS)
 		die_if_kernel("Penguin instruction from Penguin mode??!?!", regs);
-	send_sig_fault(SIGILL, ILL_PRVOPC, (void __user *)pc, 0, current);
+	send_sig_fault(SIGILL, ILL_PRVOPC, (void __user *)pc, current);
 }
 
 /* XXX User may want to be allowed to do this. XXX */
@@ -145,7 +145,7 @@ void do_memaccess_unaligned(struct pt_regs *regs, unsigned long pc, unsigned lon
 #endif
 	send_sig_fault(SIGBUS, BUS_ADRALN,
 		       /* FIXME: Should dig out mna address */ (void *)0,
-		       0, current);
+		       current);
 }
 
 static unsigned long init_fsr = 0x0UL;
@@ -291,7 +291,7 @@ void do_fpe_trap(struct pt_regs *regs, unsigned long pc, unsigned long npc,
 		else if (fsr & 0x01)
 			code = FPE_FLTRES;
 	}
-	send_sig_fault(SIGFPE, code, (void __user *)pc, 0, fpt);
+	send_sig_fault(SIGFPE, code, (void __user *)pc, fpt);
 #ifndef CONFIG_SMP
 	last_task_used_math = NULL;
 #endif
@@ -305,7 +305,7 @@ void handle_tag_overflow(struct pt_regs *regs, unsigned long pc, unsigned long n
 {
 	if(psr & PSR_PS)
 		die_if_kernel("Penguin overflow trap from kernel mode", regs);
-	send_sig_fault(SIGEMT, EMT_TAGOVF, (void __user *)pc, 0, current);
+	send_sig_fault(SIGEMT, EMT_TAGOVF, (void __user *)pc, current);
 }
 
 void handle_watchpoint(struct pt_regs *regs, unsigned long pc, unsigned long npc,
@@ -327,13 +327,13 @@ void handle_reg_access(struct pt_regs *regs, unsigned long pc, unsigned long npc
 	printk("Register Access Exception at PC %08lx NPC %08lx PSR %08lx\n",
 	       pc, npc, psr);
 #endif
-	force_sig_fault(SIGBUS, BUS_OBJERR, (void __user *)pc, 0);
+	force_sig_fault(SIGBUS, BUS_OBJERR, (void __user *)pc);
 }
 
 void handle_cp_disabled(struct pt_regs *regs, unsigned long pc, unsigned long npc,
 			unsigned long psr)
 {
-	send_sig_fault(SIGILL, ILL_COPROC, (void __user *)pc, 0, current);
+	send_sig_fault(SIGILL, ILL_COPROC, (void __user *)pc, current);
 }
 
 void handle_cp_exception(struct pt_regs *regs, unsigned long pc, unsigned long npc,
@@ -343,13 +343,13 @@ void handle_cp_exception(struct pt_regs *regs, unsigned long pc, unsigned long n
 	printk("Co-Processor Exception at PC %08lx NPC %08lx PSR %08lx\n",
 	       pc, npc, psr);
 #endif
-	send_sig_fault(SIGILL, ILL_COPROC, (void __user *)pc, 0, current);
+	send_sig_fault(SIGILL, ILL_COPROC, (void __user *)pc, current);
 }
 
 void handle_hw_divzero(struct pt_regs *regs, unsigned long pc, unsigned long npc,
 		       unsigned long psr)
 {
-	send_sig_fault(SIGFPE, FPE_INTDIV, (void __user *)pc, 0, current);
+	send_sig_fault(SIGFPE, FPE_INTDIV, (void __user *)pc, current);
 }
 
 #ifdef CONFIG_DEBUG_BUGVERBOSE
diff --git a/arch/sparc/kernel/traps_64.c b/arch/sparc/kernel/traps_64.c
index a850dccd78ea..6863025ed56d 100644
--- a/arch/sparc/kernel/traps_64.c
+++ b/arch/sparc/kernel/traps_64.c
@@ -107,8 +107,8 @@ void bad_trap(struct pt_regs *regs, long lvl)
 		regs->tpc &= 0xffffffff;
 		regs->tnpc &= 0xffffffff;
 	}
-	force_sig_fault(SIGILL, ILL_ILLTRP,
-			(void __user *)regs->tpc, lvl);
+	force_sig_fault_trapno(SIGILL, ILL_ILLTRP,
+			       (void __user *)regs->tpc, lvl);
 }
 
 void bad_trap_tl1(struct pt_regs *regs, long lvl)
@@ -201,8 +201,7 @@ void spitfire_insn_access_exception(struct pt_regs *regs, unsigned long sfsr, un
 		regs->tpc &= 0xffffffff;
 		regs->tnpc &= 0xffffffff;
 	}
-	force_sig_fault(SIGSEGV, SEGV_MAPERR,
-			(void __user *)regs->tpc, 0);
+	force_sig_fault(SIGSEGV, SEGV_MAPERR, (void __user *)regs->tpc);
 out:
 	exception_exit(prev_state);
 }
@@ -237,7 +236,7 @@ void sun4v_insn_access_exception(struct pt_regs *regs, unsigned long addr, unsig
 		regs->tpc &= 0xffffffff;
 		regs->tnpc &= 0xffffffff;
 	}
-	force_sig_fault(SIGSEGV, SEGV_MAPERR, (void __user *) addr, 0);
+	force_sig_fault(SIGSEGV, SEGV_MAPERR, (void __user *) addr);
 }
 
 void sun4v_insn_access_exception_tl1(struct pt_regs *regs, unsigned long addr, unsigned long type_ctx)
@@ -321,7 +320,7 @@ void spitfire_data_access_exception(struct pt_regs *regs, unsigned long sfsr, un
 	if (is_no_fault_exception(regs))
 		return;
 
-	force_sig_fault(SIGSEGV, SEGV_MAPERR, (void __user *)sfar, 0);
+	force_sig_fault(SIGSEGV, SEGV_MAPERR, (void __user *)sfar);
 out:
 	exception_exit(prev_state);
 }
@@ -385,13 +384,13 @@ void sun4v_data_access_exception(struct pt_regs *regs, unsigned long addr, unsig
 	 */
 	switch (type) {
 	case HV_FAULT_TYPE_INV_ASI:
-		force_sig_fault(SIGILL, ILL_ILLADR, (void __user *)addr, 0);
+		force_sig_fault(SIGILL, ILL_ILLADR, (void __user *)addr);
 		break;
 	case HV_FAULT_TYPE_MCD_DIS:
-		force_sig_fault(SIGSEGV, SEGV_ACCADI, (void __user *)addr, 0);
+		force_sig_fault(SIGSEGV, SEGV_ACCADI, (void __user *)addr);
 		break;
 	default:
-		force_sig_fault(SIGSEGV, SEGV_MAPERR, (void __user *)addr, 0);
+		force_sig_fault(SIGSEGV, SEGV_MAPERR, (void __user *)addr);
 		break;
 	}
 }
@@ -568,7 +567,7 @@ static void spitfire_ue_log(unsigned long afsr, unsigned long afar, unsigned lon
 		regs->tpc &= 0xffffffff;
 		regs->tnpc &= 0xffffffff;
 	}
-	force_sig_fault(SIGBUS, BUS_OBJERR, (void *)0, 0);
+	force_sig_fault(SIGBUS, BUS_OBJERR, (void *)0);
 }
 
 void spitfire_access_error(struct pt_regs *regs, unsigned long status_encoded, unsigned long afar)
@@ -2069,8 +2068,7 @@ void do_mcd_err(struct pt_regs *regs, struct sun4v_error_entry ent)
 	/* Send SIGSEGV to the userspace process with the right signal
 	 * code
 	 */
-	force_sig_fault(SIGSEGV, SEGV_ADIDERR, (void __user *)ent.err_raddr,
-			0);
+	force_sig_fault(SIGSEGV, SEGV_ADIDERR, (void __user *)ent.err_raddr);
 }
 
 /* We run with %pil set to PIL_NORMAL_MAX and PSTATE_IE enabled in %pstate.
@@ -2184,7 +2182,7 @@ bool sun4v_nonresum_error_user_handled(struct pt_regs *regs,
 	}
 	if (attrs & SUN4V_ERR_ATTRS_PIO) {
 		force_sig_fault(SIGBUS, BUS_ADRERR,
-				(void __user *)sun4v_get_vaddr(regs), 0);
+				(void __user *)sun4v_get_vaddr(regs));
 		return true;
 	}
 
@@ -2340,8 +2338,7 @@ static void do_fpe_common(struct pt_regs *regs)
 			else if (fsr & 0x01)
 				code = FPE_FLTRES;
 		}
-		force_sig_fault(SIGFPE, code,
-				(void __user *)regs->tpc, 0);
+		force_sig_fault(SIGFPE, code, (void __user *)regs->tpc);
 	}
 }
 
@@ -2395,8 +2392,7 @@ void do_tof(struct pt_regs *regs)
 		regs->tpc &= 0xffffffff;
 		regs->tnpc &= 0xffffffff;
 	}
-	force_sig_fault(SIGEMT, EMT_TAGOVF,
-			(void __user *)regs->tpc, 0);
+	force_sig_fault(SIGEMT, EMT_TAGOVF, (void __user *)regs->tpc);
 out:
 	exception_exit(prev_state);
 }
@@ -2415,8 +2411,7 @@ void do_div0(struct pt_regs *regs)
 		regs->tpc &= 0xffffffff;
 		regs->tnpc &= 0xffffffff;
 	}
-	force_sig_fault(SIGFPE, FPE_INTDIV,
-			(void __user *)regs->tpc, 0);
+	force_sig_fault(SIGFPE, FPE_INTDIV, (void __user *)regs->tpc);
 out:
 	exception_exit(prev_state);
 }
@@ -2612,7 +2607,7 @@ void do_illegal_instruction(struct pt_regs *regs)
 			}
 		}
 	}
-	force_sig_fault(SIGILL, ILL_ILLOPC, (void __user *)pc, 0);
+	force_sig_fault(SIGILL, ILL_ILLOPC, (void __user *)pc);
 out:
 	exception_exit(prev_state);
 }
@@ -2632,7 +2627,7 @@ void mem_address_unaligned(struct pt_regs *regs, unsigned long sfar, unsigned lo
 	if (is_no_fault_exception(regs))
 		return;
 
-	force_sig_fault(SIGBUS, BUS_ADRALN, (void __user *)sfar, 0);
+	force_sig_fault(SIGBUS, BUS_ADRALN, (void __user *)sfar);
 out:
 	exception_exit(prev_state);
 }
@@ -2650,7 +2645,7 @@ void sun4v_do_mna(struct pt_regs *regs, unsigned long addr, unsigned long type_c
 	if (is_no_fault_exception(regs))
 		return;
 
-	force_sig_fault(SIGBUS, BUS_ADRALN, (void __user *) addr, 0);
+	force_sig_fault(SIGBUS, BUS_ADRALN, (void __user *) addr);
 }
 
 /* sun4v_mem_corrupt_detect_precise() - Handle precise exception on an ADI
@@ -2697,7 +2692,7 @@ void sun4v_mem_corrupt_detect_precise(struct pt_regs *regs, unsigned long addr,
 		regs->tpc &= 0xffffffff;
 		regs->tnpc &= 0xffffffff;
 	}
-	force_sig_fault(SIGSEGV, SEGV_ADIPERR, (void __user *)addr, 0);
+	force_sig_fault(SIGSEGV, SEGV_ADIPERR, (void __user *)addr);
 }
 
 void do_privop(struct pt_regs *regs)
@@ -2712,8 +2707,7 @@ void do_privop(struct pt_regs *regs)
 		regs->tpc &= 0xffffffff;
 		regs->tnpc &= 0xffffffff;
 	}
-	force_sig_fault(SIGILL, ILL_PRVOPC,
-			(void __user *)regs->tpc, 0);
+	force_sig_fault(SIGILL, ILL_PRVOPC, (void __user *)regs->tpc);
 out:
 	exception_exit(prev_state);
 }
diff --git a/arch/sparc/kernel/unaligned_32.c b/arch/sparc/kernel/unaligned_32.c
index ef5c5207c9ff..455f0258c745 100644
--- a/arch/sparc/kernel/unaligned_32.c
+++ b/arch/sparc/kernel/unaligned_32.c
@@ -278,5 +278,5 @@ asmlinkage void user_unaligned_trap(struct pt_regs *regs, unsigned int insn)
 {
 	send_sig_fault(SIGBUS, BUS_ADRALN,
 		       (void __user *)safe_compute_effective_address(regs, insn),
-		       0, current);
+		       current);
 }
diff --git a/arch/sparc/mm/fault_32.c b/arch/sparc/mm/fault_32.c
index de2031c2b2d7..fa858626b85b 100644
--- a/arch/sparc/mm/fault_32.c
+++ b/arch/sparc/mm/fault_32.c
@@ -83,7 +83,7 @@ static void __do_fault_siginfo(int code, int sig, struct pt_regs *regs,
 		show_signal_msg(regs, sig, code,
 				addr, current);
 
-	force_sig_fault(sig, code, (void __user *) addr, 0);
+	force_sig_fault(sig, code, (void __user *) addr);
 }
 
 static unsigned long compute_si_addr(struct pt_regs *regs, int text_fault)
diff --git a/arch/sparc/mm/fault_64.c b/arch/sparc/mm/fault_64.c
index 0a6bcc85fba7..9a9652a15fed 100644
--- a/arch/sparc/mm/fault_64.c
+++ b/arch/sparc/mm/fault_64.c
@@ -176,7 +176,7 @@ static void do_fault_siginfo(int code, int sig, struct pt_regs *regs,
 	if (unlikely(show_unhandled_signals))
 		show_signal_msg(regs, sig, code, addr, current);
 
-	force_sig_fault(sig, code, (void __user *) addr, 0);
+	force_sig_fault(sig, code, (void __user *) addr);
 }
 
 static unsigned int get_fault_insn(struct pt_regs *regs, unsigned int insn)
diff --git a/include/linux/sched/signal.h b/include/linux/sched/signal.h
index b9126fe06c3f..99a9ab2b169a 100644
--- a/include/linux/sched/signal.h
+++ b/include/linux/sched/signal.h
@@ -329,6 +329,7 @@ int force_sig_pkuerr(void __user *addr, u32 pkey);
 int force_sig_perf(void __user *addr, u32 type, u64 sig_data);
 
 int force_sig_ptrace_errno_trap(int errno, void __user *addr);
+int force_sig_fault_trapno(int sig, int code, void __user *addr, int trapno);
 
 extern int send_sig_info(int, struct kernel_siginfo *, struct task_struct *);
 extern void force_sigsegv(int sig);
diff --git a/kernel/signal.c b/kernel/signal.c
index a3229add4455..87a374225277 100644
--- a/kernel/signal.c
+++ b/kernel/signal.c
@@ -1808,6 +1808,22 @@ int force_sig_ptrace_errno_trap(int errno, void __user *addr)
 	return force_sig_info(&info);
 }
 
+/* For the rare architectures that include trap information using
+ * si_trapno.
+ */
+int force_sig_fault_trapno(int sig, int code, void __user *addr, int trapno)
+{
+	struct kernel_siginfo info;
+
+	clear_siginfo(&info);
+	info.si_signo = sig;
+	info.si_errno = 0;
+	info.si_code  = code;
+	info.si_addr  = addr;
+	info.si_trapno = trapno;
+	return force_sig_info(&info);
+}
+
 int kill_pgrp(struct pid *pid, int sig, int priv)
 {
 	int ret;
@@ -3243,6 +3259,9 @@ enum siginfo_layout siginfo_layout(unsigned sig, int si_code)
 #endif
 			else if ((sig == SIGTRAP) && (si_code == TRAP_PERF))
 				layout = SIL_PERF_EVENT;
+			else if (IS_ENABLED(CONFIG_SPARC) &&
+				 (sig == SIGILL) && (si_code == ILL_ILLTRP))
+				layout = SIL_FAULT_TRAPNO;
 #ifdef __ARCH_SI_TRAPNO
 			else if (layout == SIL_FAULT)
 				layout = SIL_FAULT_TRAPNO;
-- 
2.20.1

Re: [PATCH 4/6] signal/sparc: si_trapno is only used with SIGILL ILL_ILLTRP

[Marco Elver]

On Thu, 15 Jul 2021 at 20:12, Eric W. Biederman <ebiederm@xmission.com> wrote:
> While reviewing the signal handlers on sparc it became clear that
> si_trapno is only set to a non-zero value when sending SIGILL with
> si_code ILL_ILLTRP.
>
> Add force_sig_fault_trapno and send SIGILL ILL_ILLTRP with it.
>
> Remove the define of __ARCH_SI_TRAPNO and remove the always zero
> si_trapno parameter from send_sig_fault and force_sig_fault.
>
> v1: https://lkml.kernel.org/r/m1eeers7q7.fsf_-_@fess.ebiederm.org
> v2: https://lkml.kernel.org/r/20210505141101.11519-7-ebiederm@xmission.com
> Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>

Reviewed-by: Marco Elver <elver@google.com>

> ---
>  arch/sparc/include/uapi/asm/siginfo.h |  3 --
>  arch/sparc/kernel/process_64.c        |  2 +-
>  arch/sparc/kernel/sys_sparc_32.c      |  2 +-
>  arch/sparc/kernel/sys_sparc_64.c      |  2 +-
>  arch/sparc/kernel/traps_32.c          | 22 +++++++-------
>  arch/sparc/kernel/traps_64.c          | 44 ++++++++++++---------------
>  arch/sparc/kernel/unaligned_32.c      |  2 +-
>  arch/sparc/mm/fault_32.c              |  2 +-
>  arch/sparc/mm/fault_64.c              |  2 +-
>  include/linux/sched/signal.h          |  1 +
>  kernel/signal.c                       | 19 ++++++++++++
>  11 files changed, 56 insertions(+), 45 deletions(-)
>
> diff --git a/arch/sparc/include/uapi/asm/siginfo.h b/arch/sparc/include/uapi/asm/siginfo.h
> index 68bdde4c2a2e..0e7c27522aed 100644
> --- a/arch/sparc/include/uapi/asm/siginfo.h
> +++ b/arch/sparc/include/uapi/asm/siginfo.h
> @@ -8,9 +8,6 @@
>
>  #endif /* defined(__sparc__) && defined(__arch64__) */
>
> -
> -#define __ARCH_SI_TRAPNO
> -
>  #include <asm-generic/siginfo.h>
>
>
> diff --git a/arch/sparc/kernel/process_64.c b/arch/sparc/kernel/process_64.c
> index d33c58a58d4f..547b06b49ce3 100644
> --- a/arch/sparc/kernel/process_64.c
> +++ b/arch/sparc/kernel/process_64.c
> @@ -518,7 +518,7 @@ void synchronize_user_stack(void)
>
>  static void stack_unaligned(unsigned long sp)
>  {
> -       force_sig_fault(SIGBUS, BUS_ADRALN, (void __user *) sp, 0);
> +       force_sig_fault(SIGBUS, BUS_ADRALN, (void __user *) sp);
>  }
>
>  static const char uwfault32[] = KERN_INFO \
> diff --git a/arch/sparc/kernel/sys_sparc_32.c b/arch/sparc/kernel/sys_sparc_32.c
> index be77538bc038..082a551897ed 100644
> --- a/arch/sparc/kernel/sys_sparc_32.c
> +++ b/arch/sparc/kernel/sys_sparc_32.c
> @@ -151,7 +151,7 @@ sparc_breakpoint (struct pt_regs *regs)
>  #ifdef DEBUG_SPARC_BREAKPOINT
>          printk ("TRAP: Entering kernel PC=%x, nPC=%x\n", regs->pc, regs->npc);
>  #endif
> -       force_sig_fault(SIGTRAP, TRAP_BRKPT, (void __user *)regs->pc, 0);
> +       force_sig_fault(SIGTRAP, TRAP_BRKPT, (void __user *)regs->pc);
>
>  #ifdef DEBUG_SPARC_BREAKPOINT
>         printk ("TRAP: Returning to space: PC=%x nPC=%x\n", regs->pc, regs->npc);
> diff --git a/arch/sparc/kernel/sys_sparc_64.c b/arch/sparc/kernel/sys_sparc_64.c
> index 6b92fadb6ec7..1e9a9e016237 100644
> --- a/arch/sparc/kernel/sys_sparc_64.c
> +++ b/arch/sparc/kernel/sys_sparc_64.c
> @@ -514,7 +514,7 @@ asmlinkage void sparc_breakpoint(struct pt_regs *regs)
>  #ifdef DEBUG_SPARC_BREAKPOINT
>          printk ("TRAP: Entering kernel PC=%lx, nPC=%lx\n", regs->tpc, regs->tnpc);
>  #endif
> -       force_sig_fault(SIGTRAP, TRAP_BRKPT, (void __user *)regs->tpc, 0);
> +       force_sig_fault(SIGTRAP, TRAP_BRKPT, (void __user *)regs->tpc);
>  #ifdef DEBUG_SPARC_BREAKPOINT
>         printk ("TRAP: Returning to space: PC=%lx nPC=%lx\n", regs->tpc, regs->tnpc);
>  #endif
> diff --git a/arch/sparc/kernel/traps_32.c b/arch/sparc/kernel/traps_32.c
> index 247a0d9683b2..5630e5a395e0 100644
> --- a/arch/sparc/kernel/traps_32.c
> +++ b/arch/sparc/kernel/traps_32.c
> @@ -102,8 +102,8 @@ void do_hw_interrupt(struct pt_regs *regs, unsigned long type)
>         if(regs->psr & PSR_PS)
>                 die_if_kernel("Kernel bad trap", regs);
>
> -       force_sig_fault(SIGILL, ILL_ILLTRP,
> -                       (void __user *)regs->pc, type - 0x80);
> +       force_sig_fault_trapno(SIGILL, ILL_ILLTRP,
> +                              (void __user *)regs->pc, type - 0x80);
>  }
>
>  void do_illegal_instruction(struct pt_regs *regs, unsigned long pc, unsigned long npc,
> @@ -116,7 +116,7 @@ void do_illegal_instruction(struct pt_regs *regs, unsigned long pc, unsigned lon
>                regs->pc, *(unsigned long *)regs->pc);
>  #endif
>
> -       send_sig_fault(SIGILL, ILL_ILLOPC, (void __user *)pc, 0, current);
> +       send_sig_fault(SIGILL, ILL_ILLOPC, (void __user *)pc, current);
>  }
>
>  void do_priv_instruction(struct pt_regs *regs, unsigned long pc, unsigned long npc,
> @@ -124,7 +124,7 @@ void do_priv_instruction(struct pt_regs *regs, unsigned long pc, unsigned long n
>  {
>         if(psr & PSR_PS)
>                 die_if_kernel("Penguin instruction from Penguin mode??!?!", regs);
> -       send_sig_fault(SIGILL, ILL_PRVOPC, (void __user *)pc, 0, current);
> +       send_sig_fault(SIGILL, ILL_PRVOPC, (void __user *)pc, current);
>  }
>
>  /* XXX User may want to be allowed to do this. XXX */
> @@ -145,7 +145,7 @@ void do_memaccess_unaligned(struct pt_regs *regs, unsigned long pc, unsigned lon
>  #endif
>         send_sig_fault(SIGBUS, BUS_ADRALN,
>                        /* FIXME: Should dig out mna address */ (void *)0,
> -                      0, current);
> +                      current);
>  }
>
>  static unsigned long init_fsr = 0x0UL;
> @@ -291,7 +291,7 @@ void do_fpe_trap(struct pt_regs *regs, unsigned long pc, unsigned long npc,
>                 else if (fsr & 0x01)
>                         code = FPE_FLTRES;
>         }
> -       send_sig_fault(SIGFPE, code, (void __user *)pc, 0, fpt);
> +       send_sig_fault(SIGFPE, code, (void __user *)pc, fpt);
>  #ifndef CONFIG_SMP
>         last_task_used_math = NULL;
>  #endif
> @@ -305,7 +305,7 @@ void handle_tag_overflow(struct pt_regs *regs, unsigned long pc, unsigned long n
>  {
>         if(psr & PSR_PS)
>                 die_if_kernel("Penguin overflow trap from kernel mode", regs);
> -       send_sig_fault(SIGEMT, EMT_TAGOVF, (void __user *)pc, 0, current);
> +       send_sig_fault(SIGEMT, EMT_TAGOVF, (void __user *)pc, current);
>  }
>
>  void handle_watchpoint(struct pt_regs *regs, unsigned long pc, unsigned long npc,
> @@ -327,13 +327,13 @@ void handle_reg_access(struct pt_regs *regs, unsigned long pc, unsigned long npc
>         printk("Register Access Exception at PC %08lx NPC %08lx PSR %08lx\n",
>                pc, npc, psr);
>  #endif
> -       force_sig_fault(SIGBUS, BUS_OBJERR, (void __user *)pc, 0);
> +       force_sig_fault(SIGBUS, BUS_OBJERR, (void __user *)pc);
>  }
>
>  void handle_cp_disabled(struct pt_regs *regs, unsigned long pc, unsigned long npc,
>                         unsigned long psr)
>  {
> -       send_sig_fault(SIGILL, ILL_COPROC, (void __user *)pc, 0, current);
> +       send_sig_fault(SIGILL, ILL_COPROC, (void __user *)pc, current);
>  }
>
>  void handle_cp_exception(struct pt_regs *regs, unsigned long pc, unsigned long npc,
> @@ -343,13 +343,13 @@ void handle_cp_exception(struct pt_regs *regs, unsigned long pc, unsigned long n
>         printk("Co-Processor Exception at PC %08lx NPC %08lx PSR %08lx\n",
>                pc, npc, psr);
>  #endif
> -       send_sig_fault(SIGILL, ILL_COPROC, (void __user *)pc, 0, current);
> +       send_sig_fault(SIGILL, ILL_COPROC, (void __user *)pc, current);
>  }
>
>  void handle_hw_divzero(struct pt_regs *regs, unsigned long pc, unsigned long npc,
>                        unsigned long psr)
>  {
> -       send_sig_fault(SIGFPE, FPE_INTDIV, (void __user *)pc, 0, current);
> +       send_sig_fault(SIGFPE, FPE_INTDIV, (void __user *)pc, current);
>  }
>
>  #ifdef CONFIG_DEBUG_BUGVERBOSE
> diff --git a/arch/sparc/kernel/traps_64.c b/arch/sparc/kernel/traps_64.c
> index a850dccd78ea..6863025ed56d 100644
> --- a/arch/sparc/kernel/traps_64.c
> +++ b/arch/sparc/kernel/traps_64.c
> @@ -107,8 +107,8 @@ void bad_trap(struct pt_regs *regs, long lvl)
>                 regs->tpc &= 0xffffffff;
>                 regs->tnpc &= 0xffffffff;
>         }
> -       force_sig_fault(SIGILL, ILL_ILLTRP,
> -                       (void __user *)regs->tpc, lvl);
> +       force_sig_fault_trapno(SIGILL, ILL_ILLTRP,
> +                              (void __user *)regs->tpc, lvl);
>  }
>
>  void bad_trap_tl1(struct pt_regs *regs, long lvl)
> @@ -201,8 +201,7 @@ void spitfire_insn_access_exception(struct pt_regs *regs, unsigned long sfsr, un
>                 regs->tpc &= 0xffffffff;
>                 regs->tnpc &= 0xffffffff;
>         }
> -       force_sig_fault(SIGSEGV, SEGV_MAPERR,
> -                       (void __user *)regs->tpc, 0);
> +       force_sig_fault(SIGSEGV, SEGV_MAPERR, (void __user *)regs->tpc);
>  out:
>         exception_exit(prev_state);
>  }
> @@ -237,7 +236,7 @@ void sun4v_insn_access_exception(struct pt_regs *regs, unsigned long addr, unsig
>                 regs->tpc &= 0xffffffff;
>                 regs->tnpc &= 0xffffffff;
>         }
> -       force_sig_fault(SIGSEGV, SEGV_MAPERR, (void __user *) addr, 0);
> +       force_sig_fault(SIGSEGV, SEGV_MAPERR, (void __user *) addr);
>  }
>
>  void sun4v_insn_access_exception_tl1(struct pt_regs *regs, unsigned long addr, unsigned long type_ctx)
> @@ -321,7 +320,7 @@ void spitfire_data_access_exception(struct pt_regs *regs, unsigned long sfsr, un
>         if (is_no_fault_exception(regs))
>                 return;
>
> -       force_sig_fault(SIGSEGV, SEGV_MAPERR, (void __user *)sfar, 0);
> +       force_sig_fault(SIGSEGV, SEGV_MAPERR, (void __user *)sfar);
>  out:
>         exception_exit(prev_state);
>  }
> @@ -385,13 +384,13 @@ void sun4v_data_access_exception(struct pt_regs *regs, unsigned long addr, unsig
>          */
>         switch (type) {
>         case HV_FAULT_TYPE_INV_ASI:
> -               force_sig_fault(SIGILL, ILL_ILLADR, (void __user *)addr, 0);
> +               force_sig_fault(SIGILL, ILL_ILLADR, (void __user *)addr);
>                 break;
>         case HV_FAULT_TYPE_MCD_DIS:
> -               force_sig_fault(SIGSEGV, SEGV_ACCADI, (void __user *)addr, 0);
> +               force_sig_fault(SIGSEGV, SEGV_ACCADI, (void __user *)addr);
>                 break;
>         default:
> -               force_sig_fault(SIGSEGV, SEGV_MAPERR, (void __user *)addr, 0);
> +               force_sig_fault(SIGSEGV, SEGV_MAPERR, (void __user *)addr);
>                 break;
>         }
>  }
> @@ -568,7 +567,7 @@ static void spitfire_ue_log(unsigned long afsr, unsigned long afar, unsigned lon
>                 regs->tpc &= 0xffffffff;
>                 regs->tnpc &= 0xffffffff;
>         }
> -       force_sig_fault(SIGBUS, BUS_OBJERR, (void *)0, 0);
> +       force_sig_fault(SIGBUS, BUS_OBJERR, (void *)0);
>  }
>
>  void spitfire_access_error(struct pt_regs *regs, unsigned long status_encoded, unsigned long afar)
> @@ -2069,8 +2068,7 @@ void do_mcd_err(struct pt_regs *regs, struct sun4v_error_entry ent)
>         /* Send SIGSEGV to the userspace process with the right signal
>          * code
>          */
> -       force_sig_fault(SIGSEGV, SEGV_ADIDERR, (void __user *)ent.err_raddr,
> -                       0);
> +       force_sig_fault(SIGSEGV, SEGV_ADIDERR, (void __user *)ent.err_raddr);
>  }
>
>  /* We run with %pil set to PIL_NORMAL_MAX and PSTATE_IE enabled in %pstate.
> @@ -2184,7 +2182,7 @@ bool sun4v_nonresum_error_user_handled(struct pt_regs *regs,
>         }
>         if (attrs & SUN4V_ERR_ATTRS_PIO) {
>                 force_sig_fault(SIGBUS, BUS_ADRERR,
> -                               (void __user *)sun4v_get_vaddr(regs), 0);
> +                               (void __user *)sun4v_get_vaddr(regs));
>                 return true;
>         }
>
> @@ -2340,8 +2338,7 @@ static void do_fpe_common(struct pt_regs *regs)
>                         else if (fsr & 0x01)
>                                 code = FPE_FLTRES;
>                 }
> -               force_sig_fault(SIGFPE, code,
> -                               (void __user *)regs->tpc, 0);
> +               force_sig_fault(SIGFPE, code, (void __user *)regs->tpc);
>         }
>  }
>
> @@ -2395,8 +2392,7 @@ void do_tof(struct pt_regs *regs)
>                 regs->tpc &= 0xffffffff;
>                 regs->tnpc &= 0xffffffff;
>         }
> -       force_sig_fault(SIGEMT, EMT_TAGOVF,
> -                       (void __user *)regs->tpc, 0);
> +       force_sig_fault(SIGEMT, EMT_TAGOVF, (void __user *)regs->tpc);
>  out:
>         exception_exit(prev_state);
>  }
> @@ -2415,8 +2411,7 @@ void do_div0(struct pt_regs *regs)
>                 regs->tpc &= 0xffffffff;
>                 regs->tnpc &= 0xffffffff;
>         }
> -       force_sig_fault(SIGFPE, FPE_INTDIV,
> -                       (void __user *)regs->tpc, 0);
> +       force_sig_fault(SIGFPE, FPE_INTDIV, (void __user *)regs->tpc);
>  out:
>         exception_exit(prev_state);
>  }
> @@ -2612,7 +2607,7 @@ void do_illegal_instruction(struct pt_regs *regs)
>                         }
>                 }
>         }
> -       force_sig_fault(SIGILL, ILL_ILLOPC, (void __user *)pc, 0);
> +       force_sig_fault(SIGILL, ILL_ILLOPC, (void __user *)pc);
>  out:
>         exception_exit(prev_state);
>  }
> @@ -2632,7 +2627,7 @@ void mem_address_unaligned(struct pt_regs *regs, unsigned long sfar, unsigned lo
>         if (is_no_fault_exception(regs))
>                 return;
>
> -       force_sig_fault(SIGBUS, BUS_ADRALN, (void __user *)sfar, 0);
> +       force_sig_fault(SIGBUS, BUS_ADRALN, (void __user *)sfar);
>  out:
>         exception_exit(prev_state);
>  }
> @@ -2650,7 +2645,7 @@ void sun4v_do_mna(struct pt_regs *regs, unsigned long addr, unsigned long type_c
>         if (is_no_fault_exception(regs))
>                 return;
>
> -       force_sig_fault(SIGBUS, BUS_ADRALN, (void __user *) addr, 0);
> +       force_sig_fault(SIGBUS, BUS_ADRALN, (void __user *) addr);
>  }
>
>  /* sun4v_mem_corrupt_detect_precise() - Handle precise exception on an ADI
> @@ -2697,7 +2692,7 @@ void sun4v_mem_corrupt_detect_precise(struct pt_regs *regs, unsigned long addr,
>                 regs->tpc &= 0xffffffff;
>                 regs->tnpc &= 0xffffffff;
>         }
> -       force_sig_fault(SIGSEGV, SEGV_ADIPERR, (void __user *)addr, 0);
> +       force_sig_fault(SIGSEGV, SEGV_ADIPERR, (void __user *)addr);
>  }
>
>  void do_privop(struct pt_regs *regs)
> @@ -2712,8 +2707,7 @@ void do_privop(struct pt_regs *regs)
>                 regs->tpc &= 0xffffffff;
>                 regs->tnpc &= 0xffffffff;
>         }
> -       force_sig_fault(SIGILL, ILL_PRVOPC,
> -                       (void __user *)regs->tpc, 0);
> +       force_sig_fault(SIGILL, ILL_PRVOPC, (void __user *)regs->tpc);
>  out:
>         exception_exit(prev_state);
>  }
> diff --git a/arch/sparc/kernel/unaligned_32.c b/arch/sparc/kernel/unaligned_32.c
> index ef5c5207c9ff..455f0258c745 100644
> --- a/arch/sparc/kernel/unaligned_32.c
> +++ b/arch/sparc/kernel/unaligned_32.c
> @@ -278,5 +278,5 @@ asmlinkage void user_unaligned_trap(struct pt_regs *regs, unsigned int insn)
>  {
>         send_sig_fault(SIGBUS, BUS_ADRALN,
>                        (void __user *)safe_compute_effective_address(regs, insn),
> -                      0, current);
> +                      current);
>  }
> diff --git a/arch/sparc/mm/fault_32.c b/arch/sparc/mm/fault_32.c
> index de2031c2b2d7..fa858626b85b 100644
> --- a/arch/sparc/mm/fault_32.c
> +++ b/arch/sparc/mm/fault_32.c
> @@ -83,7 +83,7 @@ static void __do_fault_siginfo(int code, int sig, struct pt_regs *regs,
>                 show_signal_msg(regs, sig, code,
>                                 addr, current);
>
> -       force_sig_fault(sig, code, (void __user *) addr, 0);
> +       force_sig_fault(sig, code, (void __user *) addr);
>  }
>
>  static unsigned long compute_si_addr(struct pt_regs *regs, int text_fault)
> diff --git a/arch/sparc/mm/fault_64.c b/arch/sparc/mm/fault_64.c
> index 0a6bcc85fba7..9a9652a15fed 100644
> --- a/arch/sparc/mm/fault_64.c
> +++ b/arch/sparc/mm/fault_64.c
> @@ -176,7 +176,7 @@ static void do_fault_siginfo(int code, int sig, struct pt_regs *regs,
>         if (unlikely(show_unhandled_signals))
>                 show_signal_msg(regs, sig, code, addr, current);
>
> -       force_sig_fault(sig, code, (void __user *) addr, 0);
> +       force_sig_fault(sig, code, (void __user *) addr);
>  }
>
>  static unsigned int get_fault_insn(struct pt_regs *regs, unsigned int insn)
> diff --git a/include/linux/sched/signal.h b/include/linux/sched/signal.h
> index b9126fe06c3f..99a9ab2b169a 100644
> --- a/include/linux/sched/signal.h
> +++ b/include/linux/sched/signal.h
> @@ -329,6 +329,7 @@ int force_sig_pkuerr(void __user *addr, u32 pkey);
>  int force_sig_perf(void __user *addr, u32 type, u64 sig_data);
>
>  int force_sig_ptrace_errno_trap(int errno, void __user *addr);
> +int force_sig_fault_trapno(int sig, int code, void __user *addr, int trapno);
>
>  extern int send_sig_info(int, struct kernel_siginfo *, struct task_struct *);
>  extern void force_sigsegv(int sig);
> diff --git a/kernel/signal.c b/kernel/signal.c
> index a3229add4455..87a374225277 100644
> --- a/kernel/signal.c
> +++ b/kernel/signal.c
> @@ -1808,6 +1808,22 @@ int force_sig_ptrace_errno_trap(int errno, void __user *addr)
>         return force_sig_info(&info);
>  }
>
> +/* For the rare architectures that include trap information using
> + * si_trapno.
> + */
> +int force_sig_fault_trapno(int sig, int code, void __user *addr, int trapno)
> +{
> +       struct kernel_siginfo info;
> +
> +       clear_siginfo(&info);
> +       info.si_signo = sig;
> +       info.si_errno = 0;
> +       info.si_code  = code;
> +       info.si_addr  = addr;
> +       info.si_trapno = trapno;
> +       return force_sig_info(&info);
> +}
> +
>  int kill_pgrp(struct pid *pid, int sig, int priv)
>  {
>         int ret;
> @@ -3243,6 +3259,9 @@ enum siginfo_layout siginfo_layout(unsigned sig, int si_code)
>  #endif
>                         else if ((sig == SIGTRAP) && (si_code == TRAP_PERF))
>                                 layout = SIL_PERF_EVENT;
> +                       else if (IS_ENABLED(CONFIG_SPARC) &&
> +                                (sig == SIGILL) && (si_code == ILL_ILLTRP))
> +                               layout = SIL_FAULT_TRAPNO;
>  #ifdef __ARCH_SI_TRAPNO
>                         else if (layout == SIL_FAULT)
>                                 layout = SIL_FAULT_TRAPNO;
> --
> 2.20.1
>
> --
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[PATCH 5/6] signal/alpha: si_trapno is only used with SIGFPE and SIGTRAP TRAP_UNK

[Eric W. Biederman]

While reviewing the signal handlers on alpha it became clear that
si_trapno is only set to a non-zero value when sending SIGFPE and when
sending SITGRAP with si_code TRAP_UNK.

Add send_sig_fault_trapno and send SIGTRAP TRAP_UNK, and SIGFPE with it.

Remove the define of __ARCH_SI_TRAPNO and remove the always zero
si_trapno parameter from send_sig_fault and force_sig_fault.

v1: https://lkml.kernel.org/r/m1eeers7q7.fsf_-_@fess.ebiederm.org
v2: https://lkml.kernel.org/r/20210505141101.11519-7-ebiederm@xmission.com
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
---
 arch/alpha/include/uapi/asm/siginfo.h |  2 --
 arch/alpha/kernel/osf_sys.c           |  2 +-
 arch/alpha/kernel/signal.c            |  4 ++--
 arch/alpha/kernel/traps.c             | 26 +++++++++++++-------------
 arch/alpha/mm/fault.c                 |  4 ++--
 include/linux/sched/signal.h          |  2 ++
 kernel/signal.c                       | 21 +++++++++++++++++++++
 7 files changed, 41 insertions(+), 20 deletions(-)

diff --git a/arch/alpha/include/uapi/asm/siginfo.h b/arch/alpha/include/uapi/asm/siginfo.h
index 6e1a2af2f962..e08eae88182b 100644
--- a/arch/alpha/include/uapi/asm/siginfo.h
+++ b/arch/alpha/include/uapi/asm/siginfo.h
@@ -2,8 +2,6 @@
 #ifndef _ALPHA_SIGINFO_H
 #define _ALPHA_SIGINFO_H
 
-#define __ARCH_SI_TRAPNO
-
 #include <asm-generic/siginfo.h>
 
 #endif
diff --git a/arch/alpha/kernel/osf_sys.c b/arch/alpha/kernel/osf_sys.c
index d5367a1c6300..bbdb1a9a5fd8 100644
--- a/arch/alpha/kernel/osf_sys.c
+++ b/arch/alpha/kernel/osf_sys.c
@@ -876,7 +876,7 @@ SYSCALL_DEFINE5(osf_setsysinfo, unsigned long, op, void __user *, buffer,
 			if (fex & IEEE_TRAP_ENABLE_DZE) si_code = FPE_FLTDIV;
 			if (fex & IEEE_TRAP_ENABLE_INV) si_code = FPE_FLTINV;
 
-			send_sig_fault(SIGFPE, si_code,
+			send_sig_fault_trapno(SIGFPE, si_code,
 				       (void __user *)NULL,  /* FIXME */
 				       0, current);
  		}
diff --git a/arch/alpha/kernel/signal.c b/arch/alpha/kernel/signal.c
index 948b89789da8..bc077babafab 100644
--- a/arch/alpha/kernel/signal.c
+++ b/arch/alpha/kernel/signal.c
@@ -219,7 +219,7 @@ do_sigreturn(struct sigcontext __user *sc)
 
 	/* Send SIGTRAP if we're single-stepping: */
 	if (ptrace_cancel_bpt (current)) {
-		send_sig_fault(SIGTRAP, TRAP_BRKPT, (void __user *) regs->pc, 0,
+		send_sig_fault(SIGTRAP, TRAP_BRKPT, (void __user *) regs->pc,
 			       current);
 	}
 	return;
@@ -247,7 +247,7 @@ do_rt_sigreturn(struct rt_sigframe __user *frame)
 
 	/* Send SIGTRAP if we're single-stepping: */
 	if (ptrace_cancel_bpt (current)) {
-		send_sig_fault(SIGTRAP, TRAP_BRKPT, (void __user *) regs->pc, 0,
+		send_sig_fault(SIGTRAP, TRAP_BRKPT, (void __user *) regs->pc,
 			       current);
 	}
 	return;
diff --git a/arch/alpha/kernel/traps.c b/arch/alpha/kernel/traps.c
index 921d4b6e4d95..e9e3de18793b 100644
--- a/arch/alpha/kernel/traps.c
+++ b/arch/alpha/kernel/traps.c
@@ -227,7 +227,7 @@ do_entArith(unsigned long summary, unsigned long write_mask,
 	}
 	die_if_kernel("Arithmetic fault", regs, 0, NULL);
 
-	send_sig_fault(SIGFPE, si_code, (void __user *) regs->pc, 0, current);
+	send_sig_fault_trapno(SIGFPE, si_code, (void __user *) regs->pc, 0, current);
 }
 
 asmlinkage void
@@ -268,13 +268,13 @@ do_entIF(unsigned long type, struct pt_regs *regs)
 			regs->pc -= 4;	/* make pc point to former bpt */
 		}
 
-		send_sig_fault(SIGTRAP, TRAP_BRKPT, (void __user *)regs->pc, 0,
+		send_sig_fault(SIGTRAP, TRAP_BRKPT, (void __user *)regs->pc,
 			       current);
 		return;
 
 	      case 1: /* bugcheck */
-		send_sig_fault(SIGTRAP, TRAP_UNK, (void __user *) regs->pc, 0,
-			       current);
+		send_sig_fault_trapno(SIGTRAP, TRAP_UNK,
+				      (void __user *) regs->pc, 0, current);
 		return;
 		
 	      case 2: /* gentrap */
@@ -335,8 +335,8 @@ do_entIF(unsigned long type, struct pt_regs *regs)
 			break;
 		}
 
-		send_sig_fault(signo, code, (void __user *) regs->pc, regs->r16,
-			       current);
+		send_sig_fault_trapno(signo, code, (void __user *) regs->pc,
+				      regs->r16, current);
 		return;
 
 	      case 4: /* opDEC */
@@ -360,9 +360,9 @@ do_entIF(unsigned long type, struct pt_regs *regs)
 			if (si_code == 0)
 				return;
 			if (si_code > 0) {
-				send_sig_fault(SIGFPE, si_code,
-					       (void __user *) regs->pc, 0,
-					       current);
+				send_sig_fault_trapno(SIGFPE, si_code,
+						      (void __user *) regs->pc,
+						      0, current);
 				return;
 			}
 		}
@@ -387,7 +387,7 @@ do_entIF(unsigned long type, struct pt_regs *regs)
 		      ;
 	}
 
-	send_sig_fault(SIGILL, ILL_ILLOPC, (void __user *)regs->pc, 0, current);
+	send_sig_fault(SIGILL, ILL_ILLOPC, (void __user *)regs->pc, current);
 }
 
 /* There is an ifdef in the PALcode in MILO that enables a 
@@ -402,7 +402,7 @@ do_entDbg(struct pt_regs *regs)
 {
 	die_if_kernel("Instruction fault", regs, 0, NULL);
 
-	force_sig_fault(SIGILL, ILL_ILLOPC, (void __user *)regs->pc, 0);
+	force_sig_fault(SIGILL, ILL_ILLOPC, (void __user *)regs->pc);
 }
 
 
@@ -964,12 +964,12 @@ do_entUnaUser(void __user * va, unsigned long opcode,
 			si_code = SEGV_MAPERR;
 		mmap_read_unlock(mm);
 	}
-	send_sig_fault(SIGSEGV, si_code, va, 0, current);
+	send_sig_fault(SIGSEGV, si_code, va, current);
 	return;
 
 give_sigbus:
 	regs->pc -= 4;
-	send_sig_fault(SIGBUS, BUS_ADRALN, va, 0, current);
+	send_sig_fault(SIGBUS, BUS_ADRALN, va, current);
 	return;
 }
 
diff --git a/arch/alpha/mm/fault.c b/arch/alpha/mm/fault.c
index 09172f017efc..eee5102c3d88 100644
--- a/arch/alpha/mm/fault.c
+++ b/arch/alpha/mm/fault.c
@@ -219,13 +219,13 @@ do_page_fault(unsigned long address, unsigned long mmcsr,
 	mmap_read_unlock(mm);
 	/* Send a sigbus, regardless of whether we were in kernel
 	   or user mode.  */
-	force_sig_fault(SIGBUS, BUS_ADRERR, (void __user *) address, 0);
+	force_sig_fault(SIGBUS, BUS_ADRERR, (void __user *) address);
 	if (!user_mode(regs))
 		goto no_context;
 	return;
 
  do_sigsegv:
-	force_sig_fault(SIGSEGV, si_code, (void __user *) address, 0);
+	force_sig_fault(SIGSEGV, si_code, (void __user *) address);
 	return;
 
 #ifdef CONFIG_ALPHA_LARGE_VMALLOC
diff --git a/include/linux/sched/signal.h b/include/linux/sched/signal.h
index 99a9ab2b169a..6657184cef07 100644
--- a/include/linux/sched/signal.h
+++ b/include/linux/sched/signal.h
@@ -330,6 +330,8 @@ int force_sig_perf(void __user *addr, u32 type, u64 sig_data);
 
 int force_sig_ptrace_errno_trap(int errno, void __user *addr);
 int force_sig_fault_trapno(int sig, int code, void __user *addr, int trapno);
+int send_sig_fault_trapno(int sig, int code, void __user *addr, int trapno,
+			struct task_struct *t);
 
 extern int send_sig_info(int, struct kernel_siginfo *, struct task_struct *);
 extern void force_sigsegv(int sig);
diff --git a/kernel/signal.c b/kernel/signal.c
index 87a374225277..ae06a424aa72 100644
--- a/kernel/signal.c
+++ b/kernel/signal.c
@@ -1824,6 +1824,23 @@ int force_sig_fault_trapno(int sig, int code, void __user *addr, int trapno)
 	return force_sig_info(&info);
 }
 
+/* For the rare architectures that include trap information using
+ * si_trapno.
+ */
+int send_sig_fault_trapno(int sig, int code, void __user *addr, int trapno,
+			  struct task_struct *t)
+{
+	struct kernel_siginfo info;
+
+	clear_siginfo(&info);
+	info.si_signo = sig;
+	info.si_errno = 0;
+	info.si_code  = code;
+	info.si_addr  = addr;
+	info.si_trapno = trapno;
+	return send_sig_info(info.si_signo, &info, t);
+}
+
 int kill_pgrp(struct pid *pid, int sig, int priv)
 {
 	int ret;
@@ -3262,6 +3279,10 @@ enum siginfo_layout siginfo_layout(unsigned sig, int si_code)
 			else if (IS_ENABLED(CONFIG_SPARC) &&
 				 (sig == SIGILL) && (si_code == ILL_ILLTRP))
 				layout = SIL_FAULT_TRAPNO;
+			else if (IS_ENABLED(CONFIG_ALPHA) &&
+				 ((sig == SIGFPE) ||
+				  ((sig == SIGTRAP) && (si_code == TRAP_UNK))))
+				layout = SIL_FAULT_TRAPNO;
 #ifdef __ARCH_SI_TRAPNO
 			else if (layout == SIL_FAULT)
 				layout = SIL_FAULT_TRAPNO;
-- 
2.20.1

Re: [PATCH 5/6] signal/alpha: si_trapno is only used with SIGFPE and SIGTRAP TRAP_UNK

[Marco Elver]

On Thu, 15 Jul 2021 at 20:13, Eric W. Biederman <ebiederm@xmission.com> wrote:
> While reviewing the signal handlers on alpha it became clear that
> si_trapno is only set to a non-zero value when sending SIGFPE and when
> sending SITGRAP with si_code TRAP_UNK.
>
> Add send_sig_fault_trapno and send SIGTRAP TRAP_UNK, and SIGFPE with it.
>
> Remove the define of __ARCH_SI_TRAPNO and remove the always zero
> si_trapno parameter from send_sig_fault and force_sig_fault.
>
> v1: https://lkml.kernel.org/r/m1eeers7q7.fsf_-_@fess.ebiederm.org
> v2: https://lkml.kernel.org/r/20210505141101.11519-7-ebiederm@xmission.com
> Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>

Reviewed-by: Marco Elver <elver@google.com>

> ---
>  arch/alpha/include/uapi/asm/siginfo.h |  2 --
>  arch/alpha/kernel/osf_sys.c           |  2 +-
>  arch/alpha/kernel/signal.c            |  4 ++--
>  arch/alpha/kernel/traps.c             | 26 +++++++++++++-------------
>  arch/alpha/mm/fault.c                 |  4 ++--
>  include/linux/sched/signal.h          |  2 ++
>  kernel/signal.c                       | 21 +++++++++++++++++++++
>  7 files changed, 41 insertions(+), 20 deletions(-)
>
> diff --git a/arch/alpha/include/uapi/asm/siginfo.h b/arch/alpha/include/uapi/asm/siginfo.h
> index 6e1a2af2f962..e08eae88182b 100644
> --- a/arch/alpha/include/uapi/asm/siginfo.h
> +++ b/arch/alpha/include/uapi/asm/siginfo.h
> @@ -2,8 +2,6 @@
>  #ifndef _ALPHA_SIGINFO_H
>  #define _ALPHA_SIGINFO_H
>
> -#define __ARCH_SI_TRAPNO
> -
>  #include <asm-generic/siginfo.h>
>
>  #endif
> diff --git a/arch/alpha/kernel/osf_sys.c b/arch/alpha/kernel/osf_sys.c
> index d5367a1c6300..bbdb1a9a5fd8 100644
> --- a/arch/alpha/kernel/osf_sys.c
> +++ b/arch/alpha/kernel/osf_sys.c
> @@ -876,7 +876,7 @@ SYSCALL_DEFINE5(osf_setsysinfo, unsigned long, op, void __user *, buffer,
>                         if (fex & IEEE_TRAP_ENABLE_DZE) si_code = FPE_FLTDIV;
>                         if (fex & IEEE_TRAP_ENABLE_INV) si_code = FPE_FLTINV;
>
> -                       send_sig_fault(SIGFPE, si_code,
> +                       send_sig_fault_trapno(SIGFPE, si_code,
>                                        (void __user *)NULL,  /* FIXME */
>                                        0, current);
>                 }
> diff --git a/arch/alpha/kernel/signal.c b/arch/alpha/kernel/signal.c
> index 948b89789da8..bc077babafab 100644
> --- a/arch/alpha/kernel/signal.c
> +++ b/arch/alpha/kernel/signal.c
> @@ -219,7 +219,7 @@ do_sigreturn(struct sigcontext __user *sc)
>
>         /* Send SIGTRAP if we're single-stepping: */
>         if (ptrace_cancel_bpt (current)) {
> -               send_sig_fault(SIGTRAP, TRAP_BRKPT, (void __user *) regs->pc, 0,
> +               send_sig_fault(SIGTRAP, TRAP_BRKPT, (void __user *) regs->pc,
>                                current);
>         }
>         return;
> @@ -247,7 +247,7 @@ do_rt_sigreturn(struct rt_sigframe __user *frame)
>
>         /* Send SIGTRAP if we're single-stepping: */
>         if (ptrace_cancel_bpt (current)) {
> -               send_sig_fault(SIGTRAP, TRAP_BRKPT, (void __user *) regs->pc, 0,
> +               send_sig_fault(SIGTRAP, TRAP_BRKPT, (void __user *) regs->pc,
>                                current);
>         }
>         return;
> diff --git a/arch/alpha/kernel/traps.c b/arch/alpha/kernel/traps.c
> index 921d4b6e4d95..e9e3de18793b 100644
> --- a/arch/alpha/kernel/traps.c
> +++ b/arch/alpha/kernel/traps.c
> @@ -227,7 +227,7 @@ do_entArith(unsigned long summary, unsigned long write_mask,
>         }
>         die_if_kernel("Arithmetic fault", regs, 0, NULL);
>
> -       send_sig_fault(SIGFPE, si_code, (void __user *) regs->pc, 0, current);
> +       send_sig_fault_trapno(SIGFPE, si_code, (void __user *) regs->pc, 0, current);
>  }
>
>  asmlinkage void
> @@ -268,13 +268,13 @@ do_entIF(unsigned long type, struct pt_regs *regs)
>                         regs->pc -= 4;  /* make pc point to former bpt */
>                 }
>
> -               send_sig_fault(SIGTRAP, TRAP_BRKPT, (void __user *)regs->pc, 0,
> +               send_sig_fault(SIGTRAP, TRAP_BRKPT, (void __user *)regs->pc,
>                                current);
>                 return;
>
>               case 1: /* bugcheck */
> -               send_sig_fault(SIGTRAP, TRAP_UNK, (void __user *) regs->pc, 0,
> -                              current);
> +               send_sig_fault_trapno(SIGTRAP, TRAP_UNK,
> +                                     (void __user *) regs->pc, 0, current);
>                 return;
>
>               case 2: /* gentrap */
> @@ -335,8 +335,8 @@ do_entIF(unsigned long type, struct pt_regs *regs)
>                         break;
>                 }
>
> -               send_sig_fault(signo, code, (void __user *) regs->pc, regs->r16,
> -                              current);
> +               send_sig_fault_trapno(signo, code, (void __user *) regs->pc,
> +                                     regs->r16, current);
>                 return;
>
>               case 4: /* opDEC */
> @@ -360,9 +360,9 @@ do_entIF(unsigned long type, struct pt_regs *regs)
>                         if (si_code == 0)
>                                 return;
>                         if (si_code > 0) {
> -                               send_sig_fault(SIGFPE, si_code,
> -                                              (void __user *) regs->pc, 0,
> -                                              current);
> +                               send_sig_fault_trapno(SIGFPE, si_code,
> +                                                     (void __user *) regs->pc,
> +                                                     0, current);
>                                 return;
>                         }
>                 }
> @@ -387,7 +387,7 @@ do_entIF(unsigned long type, struct pt_regs *regs)
>                       ;
>         }
>
> -       send_sig_fault(SIGILL, ILL_ILLOPC, (void __user *)regs->pc, 0, current);
> +       send_sig_fault(SIGILL, ILL_ILLOPC, (void __user *)regs->pc, current);
>  }
>
>  /* There is an ifdef in the PALcode in MILO that enables a
> @@ -402,7 +402,7 @@ do_entDbg(struct pt_regs *regs)
>  {
>         die_if_kernel("Instruction fault", regs, 0, NULL);
>
> -       force_sig_fault(SIGILL, ILL_ILLOPC, (void __user *)regs->pc, 0);
> +       force_sig_fault(SIGILL, ILL_ILLOPC, (void __user *)regs->pc);
>  }
>
>
> @@ -964,12 +964,12 @@ do_entUnaUser(void __user * va, unsigned long opcode,
>                         si_code = SEGV_MAPERR;
>                 mmap_read_unlock(mm);
>         }
> -       send_sig_fault(SIGSEGV, si_code, va, 0, current);
> +       send_sig_fault(SIGSEGV, si_code, va, current);
>         return;
>
>  give_sigbus:
>         regs->pc -= 4;
> -       send_sig_fault(SIGBUS, BUS_ADRALN, va, 0, current);
> +       send_sig_fault(SIGBUS, BUS_ADRALN, va, current);
>         return;
>  }
>
> diff --git a/arch/alpha/mm/fault.c b/arch/alpha/mm/fault.c
> index 09172f017efc..eee5102c3d88 100644
> --- a/arch/alpha/mm/fault.c
> +++ b/arch/alpha/mm/fault.c
> @@ -219,13 +219,13 @@ do_page_fault(unsigned long address, unsigned long mmcsr,
>         mmap_read_unlock(mm);
>         /* Send a sigbus, regardless of whether we were in kernel
>            or user mode.  */
> -       force_sig_fault(SIGBUS, BUS_ADRERR, (void __user *) address, 0);
> +       force_sig_fault(SIGBUS, BUS_ADRERR, (void __user *) address);
>         if (!user_mode(regs))
>                 goto no_context;
>         return;
>
>   do_sigsegv:
> -       force_sig_fault(SIGSEGV, si_code, (void __user *) address, 0);
> +       force_sig_fault(SIGSEGV, si_code, (void __user *) address);
>         return;
>
>  #ifdef CONFIG_ALPHA_LARGE_VMALLOC
> diff --git a/include/linux/sched/signal.h b/include/linux/sched/signal.h
> index 99a9ab2b169a..6657184cef07 100644
> --- a/include/linux/sched/signal.h
> +++ b/include/linux/sched/signal.h
> @@ -330,6 +330,8 @@ int force_sig_perf(void __user *addr, u32 type, u64 sig_data);
>
>  int force_sig_ptrace_errno_trap(int errno, void __user *addr);
>  int force_sig_fault_trapno(int sig, int code, void __user *addr, int trapno);
> +int send_sig_fault_trapno(int sig, int code, void __user *addr, int trapno,
> +                       struct task_struct *t);
>
>  extern int send_sig_info(int, struct kernel_siginfo *, struct task_struct *);
>  extern void force_sigsegv(int sig);
> diff --git a/kernel/signal.c b/kernel/signal.c
> index 87a374225277..ae06a424aa72 100644
> --- a/kernel/signal.c
> +++ b/kernel/signal.c
> @@ -1824,6 +1824,23 @@ int force_sig_fault_trapno(int sig, int code, void __user *addr, int trapno)
>         return force_sig_info(&info);
>  }
>
> +/* For the rare architectures that include trap information using
> + * si_trapno.
> + */
> +int send_sig_fault_trapno(int sig, int code, void __user *addr, int trapno,
> +                         struct task_struct *t)
> +{
> +       struct kernel_siginfo info;
> +
> +       clear_siginfo(&info);
> +       info.si_signo = sig;
> +       info.si_errno = 0;
> +       info.si_code  = code;
> +       info.si_addr  = addr;
> +       info.si_trapno = trapno;
> +       return send_sig_info(info.si_signo, &info, t);
> +}
> +
>  int kill_pgrp(struct pid *pid, int sig, int priv)
>  {
>         int ret;
> @@ -3262,6 +3279,10 @@ enum siginfo_layout siginfo_layout(unsigned sig, int si_code)
>                         else if (IS_ENABLED(CONFIG_SPARC) &&
>                                  (sig == SIGILL) && (si_code == ILL_ILLTRP))
>                                 layout = SIL_FAULT_TRAPNO;
> +                       else if (IS_ENABLED(CONFIG_ALPHA) &&
> +                                ((sig == SIGFPE) ||
> +                                 ((sig == SIGTRAP) && (si_code == TRAP_UNK))))
> +                               layout = SIL_FAULT_TRAPNO;
>  #ifdef __ARCH_SI_TRAPNO
>                         else if (layout == SIL_FAULT)
>                                 layout = SIL_FAULT_TRAPNO;
> --
> 2.20.1
>

[PATCH 6/6] signal: Remove the generic __ARCH_SI_TRAPNO support

[Eric W. Biederman]

Now that __ARCH_SI_TRAPNO is no longer set by any architecture remove
all of the code it enabled from the kernel.

On alpha and sparc a more explict approach of using
send_sig_fault_trapno or force_sig_fault_trapno in the very limited
circumstances where si_trapno was set to a non-zero value.

The generic support that is being removed always set si_trapno on all
fault signals.  With only SIGILL ILL_ILLTRAP on sparc and SIGFPE and
SIGTRAP TRAP_UNK on alpla providing si_trapno values asking all senders
of fault signals to provide an si_trapno value does not make sense.

Making si_trapno an ordinary extension of the fault siginfo layout has
enabled the architecture generic implementation of SIGTRAP TRAP_PERF,
and enables other faulting signals to grow architecture generic
senders as well.

v1: https://lkml.kernel.org/r/m18s4zs7nu.fsf_-_@fess.ebiederm.org
v2: https://lkml.kernel.org/r/20210505141101.11519-8-ebiederm@xmission.com
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
---
 arch/mips/include/uapi/asm/siginfo.h |  2 --
 include/linux/sched/signal.h         |  8 --------
 kernel/signal.c                      | 14 --------------
 3 files changed, 24 deletions(-)

diff --git a/arch/mips/include/uapi/asm/siginfo.h b/arch/mips/include/uapi/asm/siginfo.h
index c34c7eef0a1c..8cb8bd061a68 100644
--- a/arch/mips/include/uapi/asm/siginfo.h
+++ b/arch/mips/include/uapi/asm/siginfo.h
@@ -10,9 +10,7 @@
 #ifndef _UAPI_ASM_SIGINFO_H
 #define _UAPI_ASM_SIGINFO_H
 
-
 #define __ARCH_SIGEV_PREAMBLE_SIZE (sizeof(long) + 2*sizeof(int))
-#undef __ARCH_SI_TRAPNO /* exception code needs to fill this ...  */
 
 #define __ARCH_HAS_SWAPPED_SIGINFO
 
diff --git a/include/linux/sched/signal.h b/include/linux/sched/signal.h
index 6657184cef07..928e0025d358 100644
--- a/include/linux/sched/signal.h
+++ b/include/linux/sched/signal.h
@@ -298,11 +298,6 @@ static inline void kernel_signal_stop(void)
 
 	schedule();
 }
-#ifdef __ARCH_SI_TRAPNO
-# define ___ARCH_SI_TRAPNO(_a1) , _a1
-#else
-# define ___ARCH_SI_TRAPNO(_a1)
-#endif
 #ifdef __ia64__
 # define ___ARCH_SI_IA64(_a1, _a2, _a3) , _a1, _a2, _a3
 #else
@@ -310,14 +305,11 @@ static inline void kernel_signal_stop(void)
 #endif
 
 int force_sig_fault_to_task(int sig, int code, void __user *addr
-	___ARCH_SI_TRAPNO(int trapno)
 	___ARCH_SI_IA64(int imm, unsigned int flags, unsigned long isr)
 	, struct task_struct *t);
 int force_sig_fault(int sig, int code, void __user *addr
-	___ARCH_SI_TRAPNO(int trapno)
 	___ARCH_SI_IA64(int imm, unsigned int flags, unsigned long isr));
 int send_sig_fault(int sig, int code, void __user *addr
-	___ARCH_SI_TRAPNO(int trapno)
 	___ARCH_SI_IA64(int imm, unsigned int flags, unsigned long isr)
 	, struct task_struct *t);
 
diff --git a/kernel/signal.c b/kernel/signal.c
index ae06a424aa72..2181423e562a 100644
--- a/kernel/signal.c
+++ b/kernel/signal.c
@@ -1666,7 +1666,6 @@ void force_sigsegv(int sig)
 }
 
 int force_sig_fault_to_task(int sig, int code, void __user *addr
-	___ARCH_SI_TRAPNO(int trapno)
 	___ARCH_SI_IA64(int imm, unsigned int flags, unsigned long isr)
 	, struct task_struct *t)
 {
@@ -1677,9 +1676,6 @@ int force_sig_fault_to_task(int sig, int code, void __user *addr
 	info.si_errno = 0;
 	info.si_code  = code;
 	info.si_addr  = addr;
-#ifdef __ARCH_SI_TRAPNO
-	info.si_trapno = trapno;
-#endif
 #ifdef __ia64__
 	info.si_imm = imm;
 	info.si_flags = flags;
@@ -1689,16 +1685,13 @@ int force_sig_fault_to_task(int sig, int code, void __user *addr
 }
 
 int force_sig_fault(int sig, int code, void __user *addr
-	___ARCH_SI_TRAPNO(int trapno)
 	___ARCH_SI_IA64(int imm, unsigned int flags, unsigned long isr))
 {
 	return force_sig_fault_to_task(sig, code, addr
-				       ___ARCH_SI_TRAPNO(trapno)
 				       ___ARCH_SI_IA64(imm, flags, isr), current);
 }
 
 int send_sig_fault(int sig, int code, void __user *addr
-	___ARCH_SI_TRAPNO(int trapno)
 	___ARCH_SI_IA64(int imm, unsigned int flags, unsigned long isr)
 	, struct task_struct *t)
 {
@@ -1709,9 +1702,6 @@ int send_sig_fault(int sig, int code, void __user *addr
 	info.si_errno = 0;
 	info.si_code  = code;
 	info.si_addr  = addr;
-#ifdef __ARCH_SI_TRAPNO
-	info.si_trapno = trapno;
-#endif
 #ifdef __ia64__
 	info.si_imm = imm;
 	info.si_flags = flags;
@@ -3283,10 +3273,6 @@ enum siginfo_layout siginfo_layout(unsigned sig, int si_code)
 				 ((sig == SIGFPE) ||
 				  ((sig == SIGTRAP) && (si_code == TRAP_UNK))))
 				layout = SIL_FAULT_TRAPNO;
-#ifdef __ARCH_SI_TRAPNO
-			else if (layout == SIL_FAULT)
-				layout = SIL_FAULT_TRAPNO;
-#endif
 		}
 		else if (si_code <= NSIGPOLL)
 			layout = SIL_POLL;
-- 
2.20.1

Re: [PATCH 6/6] signal: Remove the generic __ARCH_SI_TRAPNO support

[Marco Elver]

On Thu, 15 Jul 2021 at 20:13, Eric W. Biederman <ebiederm@xmission.com> wrote:
> Now that __ARCH_SI_TRAPNO is no longer set by any architecture remove
> all of the code it enabled from the kernel.
>
> On alpha and sparc a more explict approach of using
> send_sig_fault_trapno or force_sig_fault_trapno in the very limited
> circumstances where si_trapno was set to a non-zero value.
>
> The generic support that is being removed always set si_trapno on all
> fault signals.  With only SIGILL ILL_ILLTRAP on sparc and SIGFPE and
> SIGTRAP TRAP_UNK on alpla providing si_trapno values asking all senders
> of fault signals to provide an si_trapno value does not make sense.
>
> Making si_trapno an ordinary extension of the fault siginfo layout has
> enabled the architecture generic implementation of SIGTRAP TRAP_PERF,
> and enables other faulting signals to grow architecture generic
> senders as well.
>
> v1: https://lkml.kernel.org/r/m18s4zs7nu.fsf_-_@fess.ebiederm.org
> v2: https://lkml.kernel.org/r/20210505141101.11519-8-ebiederm@xmission.com
> Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>

Reviewed-by: Marco Elver <elver@google.com>

> ---
>  arch/mips/include/uapi/asm/siginfo.h |  2 --
>  include/linux/sched/signal.h         |  8 --------
>  kernel/signal.c                      | 14 --------------
>  3 files changed, 24 deletions(-)
>
> diff --git a/arch/mips/include/uapi/asm/siginfo.h b/arch/mips/include/uapi/asm/siginfo.h
> index c34c7eef0a1c..8cb8bd061a68 100644
> --- a/arch/mips/include/uapi/asm/siginfo.h
> +++ b/arch/mips/include/uapi/asm/siginfo.h
> @@ -10,9 +10,7 @@
>  #ifndef _UAPI_ASM_SIGINFO_H
>  #define _UAPI_ASM_SIGINFO_H
>
> -
>  #define __ARCH_SIGEV_PREAMBLE_SIZE (sizeof(long) + 2*sizeof(int))
> -#undef __ARCH_SI_TRAPNO /* exception code needs to fill this ...  */
>
>  #define __ARCH_HAS_SWAPPED_SIGINFO
>
> diff --git a/include/linux/sched/signal.h b/include/linux/sched/signal.h
> index 6657184cef07..928e0025d358 100644
> --- a/include/linux/sched/signal.h
> +++ b/include/linux/sched/signal.h
> @@ -298,11 +298,6 @@ static inline void kernel_signal_stop(void)
>
>         schedule();
>  }
> -#ifdef __ARCH_SI_TRAPNO
> -# define ___ARCH_SI_TRAPNO(_a1) , _a1
> -#else
> -# define ___ARCH_SI_TRAPNO(_a1)
> -#endif
>  #ifdef __ia64__
>  # define ___ARCH_SI_IA64(_a1, _a2, _a3) , _a1, _a2, _a3
>  #else
> @@ -310,14 +305,11 @@ static inline void kernel_signal_stop(void)
>  #endif
>
>  int force_sig_fault_to_task(int sig, int code, void __user *addr
> -       ___ARCH_SI_TRAPNO(int trapno)
>         ___ARCH_SI_IA64(int imm, unsigned int flags, unsigned long isr)
>         , struct task_struct *t);
>  int force_sig_fault(int sig, int code, void __user *addr
> -       ___ARCH_SI_TRAPNO(int trapno)
>         ___ARCH_SI_IA64(int imm, unsigned int flags, unsigned long isr));
>  int send_sig_fault(int sig, int code, void __user *addr
> -       ___ARCH_SI_TRAPNO(int trapno)
>         ___ARCH_SI_IA64(int imm, unsigned int flags, unsigned long isr)
>         , struct task_struct *t);
>
> diff --git a/kernel/signal.c b/kernel/signal.c
> index ae06a424aa72..2181423e562a 100644
> --- a/kernel/signal.c
> +++ b/kernel/signal.c
> @@ -1666,7 +1666,6 @@ void force_sigsegv(int sig)
>  }
>
>  int force_sig_fault_to_task(int sig, int code, void __user *addr
> -       ___ARCH_SI_TRAPNO(int trapno)
>         ___ARCH_SI_IA64(int imm, unsigned int flags, unsigned long isr)
>         , struct task_struct *t)
>  {
> @@ -1677,9 +1676,6 @@ int force_sig_fault_to_task(int sig, int code, void __user *addr
>         info.si_errno = 0;
>         info.si_code  = code;
>         info.si_addr  = addr;
> -#ifdef __ARCH_SI_TRAPNO
> -       info.si_trapno = trapno;
> -#endif
>  #ifdef __ia64__
>         info.si_imm = imm;
>         info.si_flags = flags;
> @@ -1689,16 +1685,13 @@ int force_sig_fault_to_task(int sig, int code, void __user *addr
>  }
>
>  int force_sig_fault(int sig, int code, void __user *addr
> -       ___ARCH_SI_TRAPNO(int trapno)
>         ___ARCH_SI_IA64(int imm, unsigned int flags, unsigned long isr))
>  {
>         return force_sig_fault_to_task(sig, code, addr
> -                                      ___ARCH_SI_TRAPNO(trapno)
>                                        ___ARCH_SI_IA64(imm, flags, isr), current);
>  }
>
>  int send_sig_fault(int sig, int code, void __user *addr
> -       ___ARCH_SI_TRAPNO(int trapno)
>         ___ARCH_SI_IA64(int imm, unsigned int flags, unsigned long isr)
>         , struct task_struct *t)
>  {
> @@ -1709,9 +1702,6 @@ int send_sig_fault(int sig, int code, void __user *addr
>         info.si_errno = 0;
>         info.si_code  = code;
>         info.si_addr  = addr;
> -#ifdef __ARCH_SI_TRAPNO
> -       info.si_trapno = trapno;
> -#endif
>  #ifdef __ia64__
>         info.si_imm = imm;
>         info.si_flags = flags;
> @@ -3283,10 +3273,6 @@ enum siginfo_layout siginfo_layout(unsigned sig, int si_code)
>                                  ((sig == SIGFPE) ||
>                                   ((sig == SIGTRAP) && (si_code == TRAP_UNK))))
>                                 layout = SIL_FAULT_TRAPNO;
> -#ifdef __ARCH_SI_TRAPNO
> -                       else if (layout == SIL_FAULT)
> -                               layout = SIL_FAULT_TRAPNO;
> -#endif
>                 }
>                 else if (si_code <= NSIGPOLL)
>                         layout = SIL_POLL;
> --
> 2.20.1
>

Re: [PATCH 0/6] Final si_trapno bits

[Marco Elver]

On Thu, Jul 15, 2021 at 01:09PM -0500, Eric W. Biederman wrote:
> As a part of a fix for the ABI of the newly added SIGTRAP TRAP_PERF a
> si_trapno was reduced to an ordinary extention of the _sigfault case
> of struct siginfo.
> 
> When Linus saw the complete set of changes come in as a fix he requested
> that the set of changes be trimmed down to just what was necessary to
> fix the SIGTRAP TRAP_PERF ABI.
> 
> I had intended to get the rest of the changes into the merge window for
> v5.14 but I dropped the ball.
> 
> I have made the changes to stop using __ARCH_SI_TRAPNO be per
> architecture so they are easier to review.  In doing so I found one
> place on alpha where I used send_sig_fault instead of
> send_sig_fault_trapno(... si_trapno = 0).  That would not have changed
> the userspace behavior but it did make the kernel code less clear.
> 
> My rule in these patches is everywhere that siginfo layout calls
> for SIL_FAULT_TRAPNO the code uses either force_sig_fault_trapno
> or send_sig_fault_trapno.
> 
> And of course I have rebased and compile tested Marco's compile time
> assert patches.
> 
> Eric
> 
> 
> Eric W. Biederman (3):
>       signal/sparc: si_trapno is only used with SIGILL ILL_ILLTRP
>       signal/alpha: si_trapno is only used with SIGFPE and SIGTRAP TRAP_UNK
>       signal: Remove the generic __ARCH_SI_TRAPNO support
> 
> Marco Elver (3):
>       sparc64: Add compile-time asserts for siginfo_t offsets
>       arm: Add compile-time asserts for siginfo_t offsets
>       arm64: Add compile-time asserts for siginfo_t offsets

Nice, thanks for the respin. If I diffed it right, I see this is almost
(modulo what you mentioned above) equivalent to:
  https://lore.kernel.org/linux-api/m1tuni8ano.fsf_-_@fess.ebiederm.org/
+ what's already in mainline. It's only missing:

	signal: Verify the alignment and size of siginfo_t
	signal: Rename SIL_PERF_EVENT SIL_FAULT_PERF_EVENT for consistency

Would this be appropriate for this series, or rather separately, or
dropped completely?

Thanks,
-- Marco

Re: [PATCH 0/6] Final si_trapno bits

[Eric W. Biederman]

Marco Elver <elver@google.com> writes:

> On Thu, Jul 15, 2021 at 01:09PM -0500, Eric W. Biederman wrote:
>> As a part of a fix for the ABI of the newly added SIGTRAP TRAP_PERF a
>> si_trapno was reduced to an ordinary extention of the _sigfault case
>> of struct siginfo.
>> 
>> When Linus saw the complete set of changes come in as a fix he requested
>> that the set of changes be trimmed down to just what was necessary to
>> fix the SIGTRAP TRAP_PERF ABI.
>> 
>> I had intended to get the rest of the changes into the merge window for
>> v5.14 but I dropped the ball.
>> 
>> I have made the changes to stop using __ARCH_SI_TRAPNO be per
>> architecture so they are easier to review.  In doing so I found one
>> place on alpha where I used send_sig_fault instead of
>> send_sig_fault_trapno(... si_trapno = 0).  That would not have changed
>> the userspace behavior but it did make the kernel code less clear.
>> 
>> My rule in these patches is everywhere that siginfo layout calls
>> for SIL_FAULT_TRAPNO the code uses either force_sig_fault_trapno
>> or send_sig_fault_trapno.
>> 
>> And of course I have rebased and compile tested Marco's compile time
>> assert patches.
>> 
>> Eric
>> 
>> 
>> Eric W. Biederman (3):
>>       signal/sparc: si_trapno is only used with SIGILL ILL_ILLTRP
>>       signal/alpha: si_trapno is only used with SIGFPE and SIGTRAP TRAP_UNK
>>       signal: Remove the generic __ARCH_SI_TRAPNO support
>> 
>> Marco Elver (3):
>>       sparc64: Add compile-time asserts for siginfo_t offsets
>>       arm: Add compile-time asserts for siginfo_t offsets
>>       arm64: Add compile-time asserts for siginfo_t offsets
>
> Nice, thanks for the respin. If I diffed it right, I see this is almost
> (modulo what you mentioned above) equivalent to:
>   https://lore.kernel.org/linux-api/m1tuni8ano.fsf_-_@fess.ebiederm.org/
> + what's already in mainline. It's only missing:
>
> 	signal: Verify the alignment and size of siginfo_t
> 	signal: Rename SIL_PERF_EVENT SIL_FAULT_PERF_EVENT for consistency
>
> Would this be appropriate for this series, or rather separately, or
> dropped completely?

Appropriate I just overlooked them.

Eric

Re: [PATCH 0/6] Final si_trapno bits

[Marco Elver]

On Fri, 16 Jul 2021 at 18:09, Eric W. Biederman <ebiederm@xmission.com> wrote:
> Marco Elver <elver@google.com> writes:
> > On Thu, Jul 15, 2021 at 01:09PM -0500, Eric W. Biederman wrote:
> >> As a part of a fix for the ABI of the newly added SIGTRAP TRAP_PERF a
> >> si_trapno was reduced to an ordinary extention of the _sigfault case
> >> of struct siginfo.
> >>
> >> When Linus saw the complete set of changes come in as a fix he requested
> >> that the set of changes be trimmed down to just what was necessary to
> >> fix the SIGTRAP TRAP_PERF ABI.
> >>
> >> I had intended to get the rest of the changes into the merge window for
> >> v5.14 but I dropped the ball.
> >>
> >> I have made the changes to stop using __ARCH_SI_TRAPNO be per
> >> architecture so they are easier to review.  In doing so I found one
> >> place on alpha where I used send_sig_fault instead of
> >> send_sig_fault_trapno(... si_trapno = 0).  That would not have changed
> >> the userspace behavior but it did make the kernel code less clear.
> >>
> >> My rule in these patches is everywhere that siginfo layout calls
> >> for SIL_FAULT_TRAPNO the code uses either force_sig_fault_trapno
> >> or send_sig_fault_trapno.
> >>
> >> And of course I have rebased and compile tested Marco's compile time
> >> assert patches.
> >>
> >> Eric
> >>
> >>
> >> Eric W. Biederman (3):
> >>       signal/sparc: si_trapno is only used with SIGILL ILL_ILLTRP
> >>       signal/alpha: si_trapno is only used with SIGFPE and SIGTRAP TRAP_UNK
> >>       signal: Remove the generic __ARCH_SI_TRAPNO support
> >>
> >> Marco Elver (3):
> >>       sparc64: Add compile-time asserts for siginfo_t offsets
> >>       arm: Add compile-time asserts for siginfo_t offsets
> >>       arm64: Add compile-time asserts for siginfo_t offsets
> >
> > Nice, thanks for the respin. If I diffed it right, I see this is almost
> > (modulo what you mentioned above) equivalent to:
> >   https://lore.kernel.org/linux-api/m1tuni8ano.fsf_-_@fess.ebiederm.org/
> > + what's already in mainline. It's only missing:
> >
> >       signal: Verify the alignment and size of siginfo_t
> >       signal: Rename SIL_PERF_EVENT SIL_FAULT_PERF_EVENT for consistency
> >
> > Would this be appropriate for this series, or rather separately, or
> > dropped completely?
>
> Appropriate I just overlooked them.

Full series with the 2 patches just sent looks good to me.

Thanks,
-- Marco

[PATCH 7/7] signal: Verify the alignment and size of siginfo_t

[Eric W. Biederman]

Update the static assertions about siginfo_t to also describe
it's alignment and size.

While investigating if it was possible to add a 64bit field into
siginfo_t[1] it became apparent that the alignment of siginfo_t
is as much a part of the ABI as the size of the structure.

If the alignment changes siginfo_t when embedded in another structure
can move to a different offset.  Which is not acceptable from an ABI
structure.

So document that fact and add static assertions to notify developers
if they change change the alignment by accident.

[1] https://lkml.kernel.org/r/YJEZdhe6JGFNYlum@elver.google.com
Acked-by: Marco Elver <elver@google.com>
v1: https://lkml.kernel.org/r/20210505141101.11519-4-ebiederm@xmission.co
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
---
 arch/arm/kernel/signal.c           | 2 ++
 arch/arm64/kernel/signal.c         | 2 ++
 arch/arm64/kernel/signal32.c       | 2 ++
 arch/sparc/kernel/signal32.c       | 2 ++
 arch/sparc/kernel/signal_64.c      | 2 ++
 arch/x86/kernel/signal_compat.c    | 6 ++++++
 include/uapi/asm-generic/siginfo.h | 5 +++++
 7 files changed, 21 insertions(+)

diff --git a/arch/arm/kernel/signal.c b/arch/arm/kernel/signal.c
index 7ef453e8a96f..f3800c0f428b 100644
--- a/arch/arm/kernel/signal.c
+++ b/arch/arm/kernel/signal.c
@@ -737,6 +737,8 @@ static_assert(NSIGBUS	== 5);
 static_assert(NSIGTRAP	== 6);
 static_assert(NSIGCHLD	== 6);
 static_assert(NSIGSYS	== 2);
+static_assert(sizeof(siginfo_t) == 128);
+static_assert(__alignof__(siginfo_t) == 4);
 static_assert(offsetof(siginfo_t, si_signo)	== 0x00);
 static_assert(offsetof(siginfo_t, si_errno)	== 0x04);
 static_assert(offsetof(siginfo_t, si_code)	== 0x08);
diff --git a/arch/arm64/kernel/signal.c b/arch/arm64/kernel/signal.c
index 4413b6a4e32a..d3721e01441b 100644
--- a/arch/arm64/kernel/signal.c
+++ b/arch/arm64/kernel/signal.c
@@ -1011,6 +1011,8 @@ static_assert(NSIGBUS	== 5);
 static_assert(NSIGTRAP	== 6);
 static_assert(NSIGCHLD	== 6);
 static_assert(NSIGSYS	== 2);
+static_assert(sizeof(siginfo_t) == 128);
+static_assert(__alignof__(siginfo_t) == 8);
 static_assert(offsetof(siginfo_t, si_signo)	== 0x00);
 static_assert(offsetof(siginfo_t, si_errno)	== 0x04);
 static_assert(offsetof(siginfo_t, si_code)	== 0x08);
diff --git a/arch/arm64/kernel/signal32.c b/arch/arm64/kernel/signal32.c
index ab1775216712..d3be01c46bec 100644
--- a/arch/arm64/kernel/signal32.c
+++ b/arch/arm64/kernel/signal32.c
@@ -469,6 +469,8 @@ static_assert(NSIGBUS	== 5);
 static_assert(NSIGTRAP	== 6);
 static_assert(NSIGCHLD	== 6);
 static_assert(NSIGSYS	== 2);
+static_assert(sizeof(compat_siginfo_t) == 128);
+static_assert(__alignof__(compat_siginfo_t) == 4);
 static_assert(offsetof(compat_siginfo_t, si_signo)	== 0x00);
 static_assert(offsetof(compat_siginfo_t, si_errno)	== 0x04);
 static_assert(offsetof(compat_siginfo_t, si_code)	== 0x08);
diff --git a/arch/sparc/kernel/signal32.c b/arch/sparc/kernel/signal32.c
index 65fd26ae9d25..4276b9e003ca 100644
--- a/arch/sparc/kernel/signal32.c
+++ b/arch/sparc/kernel/signal32.c
@@ -757,6 +757,8 @@ static_assert(NSIGBUS	== 5);
 static_assert(NSIGTRAP	== 6);
 static_assert(NSIGCHLD	== 6);
 static_assert(NSIGSYS	== 2);
+static_assert(sizeof(compat_siginfo_t) == 128);
+static_assert(__alignof__(compat_siginfo_t) == 4);
 static_assert(offsetof(compat_siginfo_t, si_signo)	== 0x00);
 static_assert(offsetof(compat_siginfo_t, si_errno)	== 0x04);
 static_assert(offsetof(compat_siginfo_t, si_code)	== 0x08);
diff --git a/arch/sparc/kernel/signal_64.c b/arch/sparc/kernel/signal_64.c
index a58e0cc45d24..cea23cf95600 100644
--- a/arch/sparc/kernel/signal_64.c
+++ b/arch/sparc/kernel/signal_64.c
@@ -567,6 +567,8 @@ static_assert(NSIGBUS	== 5);
 static_assert(NSIGTRAP	== 6);
 static_assert(NSIGCHLD	== 6);
 static_assert(NSIGSYS	== 2);
+static_assert(sizeof(siginfo_t) == 128);
+static_assert(__alignof__(siginfo_t) == 8);
 static_assert(offsetof(siginfo_t, si_signo)	== 0x00);
 static_assert(offsetof(siginfo_t, si_errno)	== 0x04);
 static_assert(offsetof(siginfo_t, si_code)	== 0x08);
diff --git a/arch/x86/kernel/signal_compat.c b/arch/x86/kernel/signal_compat.c
index 06743ec054d2..b52407c56000 100644
--- a/arch/x86/kernel/signal_compat.c
+++ b/arch/x86/kernel/signal_compat.c
@@ -34,7 +34,13 @@ static inline void signal_compat_build_tests(void)
 	BUILD_BUG_ON(NSIGSYS  != 2);
 
 	/* This is part of the ABI and can never change in size: */
+	BUILD_BUG_ON(sizeof(siginfo_t) != 128);
 	BUILD_BUG_ON(sizeof(compat_siginfo_t) != 128);
+
+	/* This is a part of the ABI and can never change in alignment */
+	BUILD_BUG_ON(__alignof__(siginfo_t) != 8);
+	BUILD_BUG_ON(__alignof__(compat_siginfo_t) != 4);
+
 	/*
 	 * The offsets of all the (unioned) si_fields are fixed
 	 * in the ABI, of course.  Make sure none of them ever
diff --git a/include/uapi/asm-generic/siginfo.h b/include/uapi/asm-generic/siginfo.h
index 5a3c221f4c9d..3ba180f550d7 100644
--- a/include/uapi/asm-generic/siginfo.h
+++ b/include/uapi/asm-generic/siginfo.h
@@ -29,6 +29,11 @@ typedef union sigval {
 #define __ARCH_SI_ATTRIBUTES
 #endif
 
+/*
+ * Be careful when extending this union.  On 32bit siginfo_t is 32bit
+ * aligned.  Which means that a 64bit field or any other field that
+ * would increase the alignment of siginfo_t will break the ABI.
+ */
 union __sifields {
 	/* kill() */
 	struct {
-- 
2.20.1

[PATCH 8/6] signal: Rename SIL_PERF_EVENT SIL_FAULT_PERF_EVENT for consistency

[Eric W. Biederman]

It helps to know which part of the siginfo structure the siginfo_layout
value is talking about.

v1: https://lkml.kernel.org/r/m18s4zs7nu.fsf_-_@fess.ebiederm.org
v2: https://lkml.kernel.org/r/20210505141101.11519-9-ebiederm@xmission.com
Acked-by: Marco Elver <elver@google.com>
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
---
 fs/signalfd.c          |  4 ++--
 include/linux/signal.h |  2 +-
 kernel/signal.c        | 10 +++++-----
 3 files changed, 8 insertions(+), 8 deletions(-)

diff --git a/fs/signalfd.c b/fs/signalfd.c
index 167b5889db4b..040e1cf90528 100644
--- a/fs/signalfd.c
+++ b/fs/signalfd.c
@@ -114,10 +114,10 @@ static int signalfd_copyinfo(struct signalfd_siginfo __user *uinfo,
 		break;
 	case SIL_FAULT_BNDERR:
 	case SIL_FAULT_PKUERR:
-	case SIL_PERF_EVENT:
+	case SIL_FAULT_PERF_EVENT:
 		/*
 		 * Fall through to the SIL_FAULT case.  SIL_FAULT_BNDERR,
-		 * SIL_FAULT_PKUERR, and SIL_PERF_EVENT are only
+		 * SIL_FAULT_PKUERR, and SIL_FAULT_PERF_EVENT are only
 		 * generated by faults that deliver them synchronously to
 		 * userspace.  In case someone injects one of these signals
 		 * and signalfd catches it treat it as SIL_FAULT.
diff --git a/include/linux/signal.h b/include/linux/signal.h
index 3454c7ff0778..3f96a6374e4f 100644
--- a/include/linux/signal.h
+++ b/include/linux/signal.h
@@ -44,7 +44,7 @@ enum siginfo_layout {
 	SIL_FAULT_MCEERR,
 	SIL_FAULT_BNDERR,
 	SIL_FAULT_PKUERR,
-	SIL_PERF_EVENT,
+	SIL_FAULT_PERF_EVENT,
 	SIL_CHLD,
 	SIL_RT,
 	SIL_SYS,
diff --git a/kernel/signal.c b/kernel/signal.c
index 2181423e562a..332b21f2fe72 100644
--- a/kernel/signal.c
+++ b/kernel/signal.c
@@ -1213,7 +1213,7 @@ static inline bool has_si_pid_and_uid(struct kernel_siginfo *info)
 	case SIL_FAULT_MCEERR:
 	case SIL_FAULT_BNDERR:
 	case SIL_FAULT_PKUERR:
-	case SIL_PERF_EVENT:
+	case SIL_FAULT_PERF_EVENT:
 	case SIL_SYS:
 		ret = false;
 		break;
@@ -2580,7 +2580,7 @@ static void hide_si_addr_tag_bits(struct ksignal *ksig)
 	case SIL_FAULT_MCEERR:
 	case SIL_FAULT_BNDERR:
 	case SIL_FAULT_PKUERR:
-	case SIL_PERF_EVENT:
+	case SIL_FAULT_PERF_EVENT:
 		ksig->info.si_addr = arch_untagged_si_addr(
 			ksig->info.si_addr, ksig->sig, ksig->info.si_code);
 		break;
@@ -3265,7 +3265,7 @@ enum siginfo_layout siginfo_layout(unsigned sig, int si_code)
 				layout = SIL_FAULT_PKUERR;
 #endif
 			else if ((sig == SIGTRAP) && (si_code == TRAP_PERF))
-				layout = SIL_PERF_EVENT;
+				layout = SIL_FAULT_PERF_EVENT;
 			else if (IS_ENABLED(CONFIG_SPARC) &&
 				 (sig == SIGILL) && (si_code == ILL_ILLTRP))
 				layout = SIL_FAULT_TRAPNO;
@@ -3394,7 +3394,7 @@ void copy_siginfo_to_external32(struct compat_siginfo *to,
 		to->si_addr = ptr_to_compat(from->si_addr);
 		to->si_pkey = from->si_pkey;
 		break;
-	case SIL_PERF_EVENT:
+	case SIL_FAULT_PERF_EVENT:
 		to->si_addr = ptr_to_compat(from->si_addr);
 		to->si_perf_data = from->si_perf_data;
 		to->si_perf_type = from->si_perf_type;
@@ -3471,7 +3471,7 @@ static int post_copy_siginfo_from_user32(kernel_siginfo_t *to,
 		to->si_addr = compat_ptr(from->si_addr);
 		to->si_pkey = from->si_pkey;
 		break;
-	case SIL_PERF_EVENT:
+	case SIL_FAULT_PERF_EVENT:
 		to->si_addr = compat_ptr(from->si_addr);
 		to->si_perf_data = from->si_perf_data;
 		to->si_perf_type = from->si_perf_type;
-- 
2.20.1

Re: siginfo_t ABI break on sparc64 from si_addr_lsb move 3y ago

[Arnd Bergmann]

On Fri, Apr 30, 2021 at 7:08 PM Eric W. Biederman <ebiederm@xmission.com> wrote:
>
> The code is only safe if the analysis that says we can move si_trapno
> and perhaps the ia64 fields into the union is correct.  It looks like
> ia64 much more actively uses it's signal extension fields including for
> SIGTRAP, so I am not at all certain the generic definition of
> perf_sigtrap is safe on ia64.
>
> > I suppose in theory sparc64 or alpha might start using the other
> > fields in the future, and an application might be compiled against
> > mismatched headers, but that is unlikely and is already broken
> > with the current headers.
>
> If we localize the use of si_trapno to just a few special cases on alpha
> and sparc I think we don't even need to worry about breaking userspace
> on any architecture.  It will complicate siginfo_layout, but it is a
> complication that reflects reality.

Ok.

> I don't have a clue how any of this affects ia64.  Does perf work on
> ia64?  Does perf work on sparc, and alpha?
>
> If perf works on ia64 we need to take a hard look at what is going on
> there as well.

ia64 never had perf support. It had oprofile until very recently, and it
had a custom thing before that. My feeling is that it's increasingly
unlikely to ever gain perf support in the future, given that oprofile
(in user space) has required kernel perf support (in kernel) for a
long time and nobody cared about that being broken either.

sparc64 has perf support for Sun UltraSPARC 3/3+/3i/4+/T1/T2/T3
and Oracle SPARC T4/T5/M7 but lacks support for most CPUs from
Oracle, Fujitsu and the rest, in particular anything from the last
ten years.
Alpha has perf support for EV67, EV68, EV7, EV79, and EV69, i.e.
anything from 1996 to the end in 2004.

      Arnd