[RFC-resend 0/2] compat: in_compat_syscall() differs on x86

[RFC-resend 0/2] compat: in_compat_syscall() differs on x86

[Dmitry Safonov]

Reading xfrm (ipsec) code I've found such code:

: #ifdef CONFIG_COMPAT
:         if (in_compat_syscall())
:                 return -EOPNOTSUPP;
: #endif

While I can read that it's false on native i386, it's a bit misleading
and in result it's better to introduce a helper for that.
Grepping other code, I've found that there are already such helpers.
And the uniq behavior of in_compat_syscall() on x86 is disturbing.

Adjusting it to generic with the following..

(on the first non-resend RFC I managed to forget Cc'ing Andy..
 sorry about that, was sure I did add him).

Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: Andy Lutomirsky <luto@kernel.org>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Herbert Xu <herbert@gondor.apana.org.au>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: John Stultz <john.stultz@linaro.org>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Steffen Klassert <steffen.klassert@secunet.com>
Cc: Stephen Boyd <sboyd@kernel.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: x86@kernel.org
Cc: linux-efi@vger.kernel.org
Cc: netdev@vger.kernel.org
Cc: Dmitry Safonov <0x7f454c46@gmail.com>

Dmitry Safonov (2):
  x86/compat: Adjust in_compat_syscall() to generic code under !COMPAT
  compat: Cleanup in_compat_syscall() callers

 arch/x86/include/asm/compat.h  |  9 ++++++++-
 arch/x86/include/asm/ftrace.h  |  4 +---
 arch/x86/kernel/process_64.c   |  4 ++--
 arch/x86/kernel/sys_x86_64.c   | 11 ++++++-----
 arch/x86/mm/hugetlbpage.c      |  4 ++--
 arch/x86/mm/mmap.c             |  2 +-
 drivers/firmware/efi/efivars.c | 16 ++++------------
 include/linux/compat.h         |  4 ++--
 kernel/time/time.c             |  2 +-
 net/xfrm/xfrm_state.c          |  2 --
 net/xfrm/xfrm_user.c           |  2 --
 11 files changed, 27 insertions(+), 33 deletions(-)

-- 
2.13.6

[RFC-resend 1/2] x86/compat: Adjust in_compat_syscall() to generic code under !COMPAT

[Dmitry Safonov]

The result of in_compat_syscall() can be pictured as:

x86 platform:
    ---------------------------------------------------
    |  Arch\syscall  |  64-bit  |   ia32   |   x32    |
    |-------------------------------------------------|
    |     x86_64     |  false   |   true   |   true   |
    |-------------------------------------------------|
    |      i686      |          |  <true>  |          |
    ---------------------------------------------------

Other platforms:
    -------------------------------------------
    |  Arch\syscall  |  64-bit  |   compat    |
    |-----------------------------------------|
    |     64-bit     |  false   |    true     |
    |-----------------------------------------|
    |    32-bit(?)   |          |   <false>   |
    -------------------------------------------

As it seen, the result of in_compat_syscall() on generic 32-bit platform
differs from i686.

There is no reason for in_compat_syscall() == true on native i686.
It also easy to misread code if the result on native 32-bit platform
differs between arches.
Because of that non arch-specific code has many places with:
    if (IS_ENABLED(CONFIG_COMPAT) && in_compat_syscall())
in different variations.

It looks-like the only non-x86 code which uses in_compat_syscall() not
under CONFIG_COMPAT guard is in amd/amdkfd. But according to
the commit a18069c132cb ("amdkfd: Disable support for 32-bit user
processes"), it actually should be disabled on native i686.

Rename in_compat_syscall() to in_32bit_syscall() for x86-specific code
and make in_compat_syscall() false under !CONFIG_COMPAT.

With a following patch I'll clean generic users which were forced
to check IS_ENABLED(CONFIG_COMPAT) with in_compat_syscall().

Signed-off-by: Dmitry Safonov <dima@arista.com>
---
 arch/x86/include/asm/compat.h |  9 ++++++++-
 arch/x86/include/asm/ftrace.h |  4 +---
 arch/x86/kernel/process_64.c  |  4 ++--
 arch/x86/kernel/sys_x86_64.c  | 11 ++++++-----
 arch/x86/mm/hugetlbpage.c     |  4 ++--
 arch/x86/mm/mmap.c            |  2 +-
 include/linux/compat.h        |  4 ++--
 7 files changed, 22 insertions(+), 16 deletions(-)

diff --git a/arch/x86/include/asm/compat.h b/arch/x86/include/asm/compat.h
index fb97cf7c4137..626bcf1d037d 100644
--- a/arch/x86/include/asm/compat.h
+++ b/arch/x86/include/asm/compat.h
@@ -232,11 +232,18 @@ static inline bool in_x32_syscall(void)
 	return false;
 }
 
-static inline bool in_compat_syscall(void)
+static inline bool in_32bit_syscall(void)
 {
 	return in_ia32_syscall() || in_x32_syscall();
 }
+
+#ifdef CONFIG_COMPAT
+static inline bool in_compat_syscall(void)
+{
+	return in_32bit_syscall();
+}
 #define in_compat_syscall in_compat_syscall	/* override the generic impl */
+#endif
 
 struct compat_siginfo;
 int __copy_siginfo_to_user32(struct compat_siginfo __user *to,
diff --git a/arch/x86/include/asm/ftrace.h b/arch/x86/include/asm/ftrace.h
index c18ed65287d5..cf350639e76d 100644
--- a/arch/x86/include/asm/ftrace.h
+++ b/arch/x86/include/asm/ftrace.h
@@ -76,9 +76,7 @@ static inline bool arch_syscall_match_sym_name(const char *sym, const char *name
 #define ARCH_TRACE_IGNORE_COMPAT_SYSCALLS 1
 static inline bool arch_trace_is_compat_syscall(struct pt_regs *regs)
 {
-	if (in_compat_syscall())
-		return true;
-	return false;
+	return in_32bit_syscall();
 }
 #endif /* CONFIG_FTRACE_SYSCALLS && CONFIG_IA32_EMULATION */
 #endif /* !COMPILE_OFFSETS */
diff --git a/arch/x86/kernel/process_64.c b/arch/x86/kernel/process_64.c
index ea5ea850348d..f96d9ee80086 100644
--- a/arch/x86/kernel/process_64.c
+++ b/arch/x86/kernel/process_64.c
@@ -573,10 +573,10 @@ static void __set_personality_x32(void)
 		current->mm->context.ia32_compat = TIF_X32;
 	current->personality &= ~READ_IMPLIES_EXEC;
 	/*
-	 * in_compat_syscall() uses the presence of the x32 syscall bit
+	 * in_32bit_syscall() uses the presence of the x32 syscall bit
 	 * flag to determine compat status.  The x86 mmap() code relies on
 	 * the syscall bitness so set x32 syscall bit right here to make
-	 * in_compat_syscall() work during exec().
+	 * in_32bit_syscall() work during exec().
 	 *
 	 * Pretend to come from a x32 execve.
 	 */
diff --git a/arch/x86/kernel/sys_x86_64.c b/arch/x86/kernel/sys_x86_64.c
index 6a78d4b36a79..f7476ce23b6e 100644
--- a/arch/x86/kernel/sys_x86_64.c
+++ b/arch/x86/kernel/sys_x86_64.c
@@ -105,7 +105,7 @@ SYSCALL_DEFINE6(mmap, unsigned long, addr, unsigned long, len,
 static void find_start_end(unsigned long addr, unsigned long flags,
 		unsigned long *begin, unsigned long *end)
 {
-	if (!in_compat_syscall() && (flags & MAP_32BIT)) {
+	if (!in_32bit_syscall() && (flags & MAP_32BIT)) {
 		/* This is usually used needed to map code in small
 		   model, so it needs to be in the first 31bit. Limit
 		   it to that.  This means we need to move the
@@ -122,7 +122,7 @@ static void find_start_end(unsigned long addr, unsigned long flags,
 	}
 
 	*begin	= get_mmap_base(1);
-	if (in_compat_syscall())
+	if (in_32bit_syscall())
 		*end = task_size_32bit();
 	else
 		*end = task_size_64bit(addr > DEFAULT_MAP_WINDOW);
@@ -193,7 +193,7 @@ arch_get_unmapped_area_topdown(struct file *filp, const unsigned long addr0,
 		return addr;
 
 	/* for MAP_32BIT mappings we force the legacy mmap base */
-	if (!in_compat_syscall() && (flags & MAP_32BIT))
+	if (!in_32bit_syscall() && (flags & MAP_32BIT))
 		goto bottomup;
 
 	/* requesting a specific address */
@@ -217,9 +217,10 @@ arch_get_unmapped_area_topdown(struct file *filp, const unsigned long addr0,
 	 * If hint address is above DEFAULT_MAP_WINDOW, look for unmapped area
 	 * in the full address space.
 	 *
-	 * !in_compat_syscall() check to avoid high addresses for x32.
+	 * !in_32bit_syscall() check to avoid high addresses for x32
+	 * (and make it no op on native i386).
 	 */
-	if (addr > DEFAULT_MAP_WINDOW && !in_compat_syscall())
+	if (addr > DEFAULT_MAP_WINDOW && !in_32bit_syscall())
 		info.high_limit += TASK_SIZE_MAX - DEFAULT_MAP_WINDOW;
 
 	info.align_mask = 0;
diff --git a/arch/x86/mm/hugetlbpage.c b/arch/x86/mm/hugetlbpage.c
index 00b296617ca4..92e4c4b85bba 100644
--- a/arch/x86/mm/hugetlbpage.c
+++ b/arch/x86/mm/hugetlbpage.c
@@ -92,7 +92,7 @@ static unsigned long hugetlb_get_unmapped_area_bottomup(struct file *file,
 	 * If hint address is above DEFAULT_MAP_WINDOW, look for unmapped area
 	 * in the full address space.
 	 */
-	info.high_limit = in_compat_syscall() ?
+	info.high_limit = in_32bit_syscall() ?
 		task_size_32bit() : task_size_64bit(addr > DEFAULT_MAP_WINDOW);
 
 	info.align_mask = PAGE_MASK & ~huge_page_mask(h);
@@ -116,7 +116,7 @@ static unsigned long hugetlb_get_unmapped_area_topdown(struct file *file,
 	 * If hint address is above DEFAULT_MAP_WINDOW, look for unmapped area
 	 * in the full address space.
 	 */
-	if (addr > DEFAULT_MAP_WINDOW && !in_compat_syscall())
+	if (addr > DEFAULT_MAP_WINDOW && !in_32bit_syscall())
 		info.high_limit += TASK_SIZE_MAX - DEFAULT_MAP_WINDOW;
 
 	info.align_mask = PAGE_MASK & ~huge_page_mask(h);
diff --git a/arch/x86/mm/mmap.c b/arch/x86/mm/mmap.c
index 1e95d57760cf..db3165714521 100644
--- a/arch/x86/mm/mmap.c
+++ b/arch/x86/mm/mmap.c
@@ -166,7 +166,7 @@ unsigned long get_mmap_base(int is_legacy)
 	struct mm_struct *mm = current->mm;
 
 #ifdef CONFIG_HAVE_ARCH_COMPAT_MMAP_BASES
-	if (in_compat_syscall()) {
+	if (in_32bit_syscall()) {
 		return is_legacy ? mm->mmap_compat_legacy_base
 				 : mm->mmap_compat_base;
 	}
diff --git a/include/linux/compat.h b/include/linux/compat.h
index 1a3c4f37e908..ac643a2f5f4b 100644
--- a/include/linux/compat.h
+++ b/include/linux/compat.h
@@ -1033,9 +1033,9 @@ int kcompat_sys_fstatfs64(unsigned int fd, compat_size_t sz,
 #else /* !CONFIG_COMPAT */
 
 #define is_compat_task() (0)
-#ifndef in_compat_syscall
+/* Ensure no one redefines in_compat_syscall() under !CONFIG_COMPAT */
+#define in_compat_syscall in_compat_syscall
 static inline bool in_compat_syscall(void) { return false; }
-#endif
 
 #endif /* CONFIG_COMPAT */
 
-- 
2.13.6

[RFC-resend 2/2] compat: Cleanup in_compat_syscall() callers

[Dmitry Safonov]

Now that in_compat_syscall() == false on native i686, it's possible to
remove some ifdeffery and no more needed helpers.

Signed-off-by: Dmitry Safonov <dima@arista.com>
---
 drivers/firmware/efi/efivars.c | 16 ++++------------
 kernel/time/time.c             |  2 +-
 net/xfrm/xfrm_state.c          |  2 --
 net/xfrm/xfrm_user.c           |  2 --
 4 files changed, 5 insertions(+), 17 deletions(-)

diff --git a/drivers/firmware/efi/efivars.c b/drivers/firmware/efi/efivars.c
index 3e626fd9bd4e..8061667a6765 100644
--- a/drivers/firmware/efi/efivars.c
+++ b/drivers/firmware/efi/efivars.c
@@ -229,14 +229,6 @@ sanity_check(struct efi_variable *var, efi_char16_t *name, efi_guid_t vendor,
 	return 0;
 }
 
-static inline bool is_compat(void)
-{
-	if (IS_ENABLED(CONFIG_COMPAT) && in_compat_syscall())
-		return true;
-
-	return false;
-}
-
 static void
 copy_out_compat(struct efi_variable *dst, struct compat_efi_variable *src)
 {
@@ -263,7 +255,7 @@ efivar_store_raw(struct efivar_entry *entry, const char *buf, size_t count)
 	u8 *data;
 	int err;
 
-	if (is_compat()) {
+	if (in_compat_syscall()) {
 		struct compat_efi_variable *compat;
 
 		if (count != sizeof(*compat))
@@ -324,7 +316,7 @@ efivar_show_raw(struct efivar_entry *entry, char *buf)
 			     &entry->var.DataSize, entry->var.Data))
 		return -EIO;
 
-	if (is_compat()) {
+	if (in_compat_syscall()) {
 		compat = (struct compat_efi_variable *)buf;
 
 		size = sizeof(*compat);
@@ -418,7 +410,7 @@ static ssize_t efivar_create(struct file *filp, struct kobject *kobj,
 	struct compat_efi_variable *compat = (struct compat_efi_variable *)buf;
 	struct efi_variable *new_var = (struct efi_variable *)buf;
 	struct efivar_entry *new_entry;
-	bool need_compat = is_compat();
+	bool need_compat = in_compat_syscall();
 	efi_char16_t *name;
 	unsigned long size;
 	u32 attributes;
@@ -495,7 +487,7 @@ static ssize_t efivar_delete(struct file *filp, struct kobject *kobj,
 	if (!capable(CAP_SYS_ADMIN))
 		return -EACCES;
 
-	if (is_compat()) {
+	if (in_compat_syscall()) {
 		if (count != sizeof(*compat))
 			return -EINVAL;
 
diff --git a/kernel/time/time.c b/kernel/time/time.c
index ccdb351277ee..4638e8cb6378 100644
--- a/kernel/time/time.c
+++ b/kernel/time/time.c
@@ -863,7 +863,7 @@ int get_timespec64(struct timespec64 *ts,
 	ts->tv_sec = kts.tv_sec;
 
 	/* Zero out the padding for 32 bit systems or in compat mode */
-	if (IS_ENABLED(CONFIG_64BIT_TIME) && (!IS_ENABLED(CONFIG_64BIT) || in_compat_syscall()))
+	if (IS_ENABLED(CONFIG_64BIT_TIME) && in_compat_syscall())
 		kts.tv_nsec &= 0xFFFFFFFFUL;
 
 	ts->tv_nsec = kts.tv_nsec;
diff --git a/net/xfrm/xfrm_state.c b/net/xfrm/xfrm_state.c
index b669262682c9..dc4a9f1fb941 100644
--- a/net/xfrm/xfrm_state.c
+++ b/net/xfrm/xfrm_state.c
@@ -2077,10 +2077,8 @@ int xfrm_user_policy(struct sock *sk, int optname, u8 __user *optval, int optlen
 	struct xfrm_mgr *km;
 	struct xfrm_policy *pol = NULL;
 
-#ifdef CONFIG_COMPAT
 	if (in_compat_syscall())
 		return -EOPNOTSUPP;
-#endif
 
 	if (!optval && !optlen) {
 		xfrm_sk_policy_insert(sk, XFRM_POLICY_IN, NULL);
diff --git a/net/xfrm/xfrm_user.c b/net/xfrm/xfrm_user.c
index df7ca2dabc48..c3aedf8a99ff 100644
--- a/net/xfrm/xfrm_user.c
+++ b/net/xfrm/xfrm_user.c
@@ -2621,10 +2621,8 @@ static int xfrm_user_rcv_msg(struct sk_buff *skb, struct nlmsghdr *nlh,
 	const struct xfrm_link *link;
 	int type, err;
 
-#ifdef CONFIG_COMPAT
 	if (in_compat_syscall())
 		return -EOPNOTSUPP;
-#endif
 
 	type = nlh->nlmsg_type;
 	if (type > XFRM_MSG_MAX)
-- 
2.13.6

Re: [RFC-resend 1/2] x86/compat: Adjust in_compat_syscall() to generic code under !COMPAT

[Andy Lutomirski]

> On Oct 12, 2018, at 6:42 AM, Dmitry Safonov <dima@arista.com> wrote:
> 
> The result of in_compat_syscall() can be pictured as:
> 
> x86 platform:
>    ---------------------------------------------------
>    |  Arch\syscall  |  64-bit  |   ia32   |   x32    |
>    |-------------------------------------------------|
>    |     x86_64     |  false   |   true   |   true   |
>    |-------------------------------------------------|
>    |      i686      |          |  <true>  |          |
>    ---------------------------------------------------
> 
> Other platforms:
>    -------------------------------------------
>    |  Arch\syscall  |  64-bit  |   compat    |
>    |-----------------------------------------|
>    |     64-bit     |  false   |    true     |
>    |-----------------------------------------|
>    |    32-bit(?)   |          |   <false>   |
>    -------------------------------------------
> 
> 

Yikes. This is probably even my fault!

Reviewed-by: Andy Lutomirski <luto@kernel.org>

And, if you want:

Apologized-for-by: Andy Lutomirski <luto@kernel.org>

[tip:x86/urgent] x86/compat: Adjust in_compat_syscall() to generic code under !COMPAT

[tip-bot for Dmitry Safonov]

Commit-ID:  a846446b1914d1e3d996d657754f43fde89bab51
Gitweb:     https://git.kernel.org/tip/a846446b1914d1e3d996d657754f43fde89bab51
Author:     Dmitry Safonov <dima@arista.com>
AuthorDate: Fri, 12 Oct 2018 14:42:52 +0100
Committer:  Thomas Gleixner <tglx@linutronix.de>
CommitDate: Thu, 1 Nov 2018 12:59:25 +0100

x86/compat: Adjust in_compat_syscall() to generic code under !COMPAT

The result of in_compat_syscall() can be pictured as:

x86 platform:
    ---------------------------------------------------
    |  Arch\syscall  |  64-bit  |   ia32   |   x32    |
    |-------------------------------------------------|
    |     x86_64     |  false   |   true   |   true   |
    |-------------------------------------------------|
    |      i686      |          |  <true>  |          |
    ---------------------------------------------------

Other platforms:
    -------------------------------------------
    |  Arch\syscall  |  64-bit  |   compat    |
    |-----------------------------------------|
    |     64-bit     |  false   |    true     |
    |-----------------------------------------|
    |    32-bit(?)   |          |   <false>   |
    -------------------------------------------

As seen, the result of in_compat_syscall() on generic 32-bit platform
differs from i686.

There is no reason for in_compat_syscall() == true on native i686.  It also
easy to misread code if the result on native 32-bit platform differs
between arches.

Because of that non arch-specific code has many places with:
    if (IS_ENABLED(CONFIG_COMPAT) && in_compat_syscall())
in different variations.

It looks-like the only non-x86 code which uses in_compat_syscall() not
under CONFIG_COMPAT guard is in amd/amdkfd. But according to the commit
a18069c132cb ("amdkfd: Disable support for 32-bit user processes"), it
actually should be disabled on native i686.

Rename in_compat_syscall() to in_32bit_syscall() for x86-specific code
and make in_compat_syscall() false under !CONFIG_COMPAT.

A follow on patch will clean up generic users which were forced to check
IS_ENABLED(CONFIG_COMPAT) with in_compat_syscall().

Signed-off-by: Dmitry Safonov <dima@arista.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Andy Lutomirski <luto@kernel.org>
Cc: Dmitry Safonov <0x7f454c46@gmail.com>
Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Herbert Xu <herbert@gondor.apana.org.au>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: John Stultz <john.stultz@linaro.org>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Steffen Klassert <steffen.klassert@secunet.com>
Cc: Stephen Boyd <sboyd@kernel.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: linux-efi@vger.kernel.org
Cc: netdev@vger.kernel.org
Link: https://lkml.kernel.org/r/20181012134253.23266-2-dima@arista.com

---
 arch/x86/include/asm/compat.h |  9 ++++++++-
 arch/x86/include/asm/ftrace.h |  4 +---
 arch/x86/kernel/process_64.c  |  4 ++--
 arch/x86/kernel/sys_x86_64.c  | 11 ++++++-----
 arch/x86/mm/hugetlbpage.c     |  4 ++--
 arch/x86/mm/mmap.c            |  2 +-
 include/linux/compat.h        |  4 ++--
 7 files changed, 22 insertions(+), 16 deletions(-)

diff --git a/arch/x86/include/asm/compat.h b/arch/x86/include/asm/compat.h
index fab4df16a3c4..22c4dfe65992 100644
--- a/arch/x86/include/asm/compat.h
+++ b/arch/x86/include/asm/compat.h
@@ -217,11 +217,18 @@ static inline bool in_x32_syscall(void)
 	return false;
 }
 
-static inline bool in_compat_syscall(void)
+static inline bool in_32bit_syscall(void)
 {
 	return in_ia32_syscall() || in_x32_syscall();
 }
+
+#ifdef CONFIG_COMPAT
+static inline bool in_compat_syscall(void)
+{
+	return in_32bit_syscall();
+}
 #define in_compat_syscall in_compat_syscall	/* override the generic impl */
+#endif
 
 struct compat_siginfo;
 int __copy_siginfo_to_user32(struct compat_siginfo __user *to,
diff --git a/arch/x86/include/asm/ftrace.h b/arch/x86/include/asm/ftrace.h
index c18ed65287d5..cf350639e76d 100644
--- a/arch/x86/include/asm/ftrace.h
+++ b/arch/x86/include/asm/ftrace.h
@@ -76,9 +76,7 @@ static inline bool arch_syscall_match_sym_name(const char *sym, const char *name
 #define ARCH_TRACE_IGNORE_COMPAT_SYSCALLS 1
 static inline bool arch_trace_is_compat_syscall(struct pt_regs *regs)
 {
-	if (in_compat_syscall())
-		return true;
-	return false;
+	return in_32bit_syscall();
 }
 #endif /* CONFIG_FTRACE_SYSCALLS && CONFIG_IA32_EMULATION */
 #endif /* !COMPILE_OFFSETS */
diff --git a/arch/x86/kernel/process_64.c b/arch/x86/kernel/process_64.c
index 31b4755369f0..0e0b4288a4b2 100644
--- a/arch/x86/kernel/process_64.c
+++ b/arch/x86/kernel/process_64.c
@@ -701,10 +701,10 @@ static void __set_personality_x32(void)
 		current->mm->context.ia32_compat = TIF_X32;
 	current->personality &= ~READ_IMPLIES_EXEC;
 	/*
-	 * in_compat_syscall() uses the presence of the x32 syscall bit
+	 * in_32bit_syscall() uses the presence of the x32 syscall bit
 	 * flag to determine compat status.  The x86 mmap() code relies on
 	 * the syscall bitness so set x32 syscall bit right here to make
-	 * in_compat_syscall() work during exec().
+	 * in_32bit_syscall() work during exec().
 	 *
 	 * Pretend to come from a x32 execve.
 	 */
diff --git a/arch/x86/kernel/sys_x86_64.c b/arch/x86/kernel/sys_x86_64.c
index 6a78d4b36a79..f7476ce23b6e 100644
--- a/arch/x86/kernel/sys_x86_64.c
+++ b/arch/x86/kernel/sys_x86_64.c
@@ -105,7 +105,7 @@ out:
 static void find_start_end(unsigned long addr, unsigned long flags,
 		unsigned long *begin, unsigned long *end)
 {
-	if (!in_compat_syscall() && (flags & MAP_32BIT)) {
+	if (!in_32bit_syscall() && (flags & MAP_32BIT)) {
 		/* This is usually used needed to map code in small
 		   model, so it needs to be in the first 31bit. Limit
 		   it to that.  This means we need to move the
@@ -122,7 +122,7 @@ static void find_start_end(unsigned long addr, unsigned long flags,
 	}
 
 	*begin	= get_mmap_base(1);
-	if (in_compat_syscall())
+	if (in_32bit_syscall())
 		*end = task_size_32bit();
 	else
 		*end = task_size_64bit(addr > DEFAULT_MAP_WINDOW);
@@ -193,7 +193,7 @@ arch_get_unmapped_area_topdown(struct file *filp, const unsigned long addr0,
 		return addr;
 
 	/* for MAP_32BIT mappings we force the legacy mmap base */
-	if (!in_compat_syscall() && (flags & MAP_32BIT))
+	if (!in_32bit_syscall() && (flags & MAP_32BIT))
 		goto bottomup;
 
 	/* requesting a specific address */
@@ -217,9 +217,10 @@ get_unmapped_area:
 	 * If hint address is above DEFAULT_MAP_WINDOW, look for unmapped area
 	 * in the full address space.
 	 *
-	 * !in_compat_syscall() check to avoid high addresses for x32.
+	 * !in_32bit_syscall() check to avoid high addresses for x32
+	 * (and make it no op on native i386).
 	 */
-	if (addr > DEFAULT_MAP_WINDOW && !in_compat_syscall())
+	if (addr > DEFAULT_MAP_WINDOW && !in_32bit_syscall())
 		info.high_limit += TASK_SIZE_MAX - DEFAULT_MAP_WINDOW;
 
 	info.align_mask = 0;
diff --git a/arch/x86/mm/hugetlbpage.c b/arch/x86/mm/hugetlbpage.c
index 00b296617ca4..92e4c4b85bba 100644
--- a/arch/x86/mm/hugetlbpage.c
+++ b/arch/x86/mm/hugetlbpage.c
@@ -92,7 +92,7 @@ static unsigned long hugetlb_get_unmapped_area_bottomup(struct file *file,
 	 * If hint address is above DEFAULT_MAP_WINDOW, look for unmapped area
 	 * in the full address space.
 	 */
-	info.high_limit = in_compat_syscall() ?
+	info.high_limit = in_32bit_syscall() ?
 		task_size_32bit() : task_size_64bit(addr > DEFAULT_MAP_WINDOW);
 
 	info.align_mask = PAGE_MASK & ~huge_page_mask(h);
@@ -116,7 +116,7 @@ static unsigned long hugetlb_get_unmapped_area_topdown(struct file *file,
 	 * If hint address is above DEFAULT_MAP_WINDOW, look for unmapped area
 	 * in the full address space.
 	 */
-	if (addr > DEFAULT_MAP_WINDOW && !in_compat_syscall())
+	if (addr > DEFAULT_MAP_WINDOW && !in_32bit_syscall())
 		info.high_limit += TASK_SIZE_MAX - DEFAULT_MAP_WINDOW;
 
 	info.align_mask = PAGE_MASK & ~huge_page_mask(h);
diff --git a/arch/x86/mm/mmap.c b/arch/x86/mm/mmap.c
index 1e95d57760cf..db3165714521 100644
--- a/arch/x86/mm/mmap.c
+++ b/arch/x86/mm/mmap.c
@@ -166,7 +166,7 @@ unsigned long get_mmap_base(int is_legacy)
 	struct mm_struct *mm = current->mm;
 
 #ifdef CONFIG_HAVE_ARCH_COMPAT_MMAP_BASES
-	if (in_compat_syscall()) {
+	if (in_32bit_syscall()) {
 		return is_legacy ? mm->mmap_compat_legacy_base
 				 : mm->mmap_compat_base;
 	}
diff --git a/include/linux/compat.h b/include/linux/compat.h
index d30e4dbd4be2..f1ef24c68fcc 100644
--- a/include/linux/compat.h
+++ b/include/linux/compat.h
@@ -1029,9 +1029,9 @@ int kcompat_sys_fstatfs64(unsigned int fd, compat_size_t sz,
 #else /* !CONFIG_COMPAT */
 
 #define is_compat_task() (0)
-#ifndef in_compat_syscall
+/* Ensure no one redefines in_compat_syscall() under !CONFIG_COMPAT */
+#define in_compat_syscall in_compat_syscall
 static inline bool in_compat_syscall(void) { return false; }
-#endif
 
 #endif /* CONFIG_COMPAT */
 

[tip:x86/urgent] compat: Cleanup in_compat_syscall() callers

[tip-bot for Dmitry Safonov]

Commit-ID:  98f76206b33504b934209d16196477dfa519a807
Gitweb:     https://git.kernel.org/tip/98f76206b33504b934209d16196477dfa519a807
Author:     Dmitry Safonov <dima@arista.com>
AuthorDate: Fri, 12 Oct 2018 14:42:53 +0100
Committer:  Thomas Gleixner <tglx@linutronix.de>
CommitDate: Thu, 1 Nov 2018 13:02:21 +0100

compat: Cleanup in_compat_syscall() callers

Now that in_compat_syscall() is consistent on all architectures and does
not longer report true on native i686, the workarounds (ifdeffery and
helpers) can be removed.

Signed-off-by: Dmitry Safonov <dima@arista.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Dmitry Safonov <0x7f454c46@gmail.com>
Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: Andy Lutomirsky <luto@kernel.org>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Herbert Xu <herbert@gondor.apana.org.au>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: John Stultz <john.stultz@linaro.org>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Steffen Klassert <steffen.klassert@secunet.com>
Cc: Stephen Boyd <sboyd@kernel.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: linux-efi@vger.kernel.org
Cc: netdev@vger.kernel.org
Link: https://lkml.kernel.org/r/20181012134253.23266-3-dima@arista.com

---
 drivers/firmware/efi/efivars.c | 16 ++++------------
 kernel/time/time.c             |  2 +-
 net/xfrm/xfrm_state.c          |  2 --
 net/xfrm/xfrm_user.c           |  2 --
 4 files changed, 5 insertions(+), 17 deletions(-)

diff --git a/drivers/firmware/efi/efivars.c b/drivers/firmware/efi/efivars.c
index 3e626fd9bd4e..8061667a6765 100644
--- a/drivers/firmware/efi/efivars.c
+++ b/drivers/firmware/efi/efivars.c
@@ -229,14 +229,6 @@ sanity_check(struct efi_variable *var, efi_char16_t *name, efi_guid_t vendor,
 	return 0;
 }
 
-static inline bool is_compat(void)
-{
-	if (IS_ENABLED(CONFIG_COMPAT) && in_compat_syscall())
-		return true;
-
-	return false;
-}
-
 static void
 copy_out_compat(struct efi_variable *dst, struct compat_efi_variable *src)
 {
@@ -263,7 +255,7 @@ efivar_store_raw(struct efivar_entry *entry, const char *buf, size_t count)
 	u8 *data;
 	int err;
 
-	if (is_compat()) {
+	if (in_compat_syscall()) {
 		struct compat_efi_variable *compat;
 
 		if (count != sizeof(*compat))
@@ -324,7 +316,7 @@ efivar_show_raw(struct efivar_entry *entry, char *buf)
 			     &entry->var.DataSize, entry->var.Data))
 		return -EIO;
 
-	if (is_compat()) {
+	if (in_compat_syscall()) {
 		compat = (struct compat_efi_variable *)buf;
 
 		size = sizeof(*compat);
@@ -418,7 +410,7 @@ static ssize_t efivar_create(struct file *filp, struct kobject *kobj,
 	struct compat_efi_variable *compat = (struct compat_efi_variable *)buf;
 	struct efi_variable *new_var = (struct efi_variable *)buf;
 	struct efivar_entry *new_entry;
-	bool need_compat = is_compat();
+	bool need_compat = in_compat_syscall();
 	efi_char16_t *name;
 	unsigned long size;
 	u32 attributes;
@@ -495,7 +487,7 @@ static ssize_t efivar_delete(struct file *filp, struct kobject *kobj,
 	if (!capable(CAP_SYS_ADMIN))
 		return -EACCES;
 
-	if (is_compat()) {
+	if (in_compat_syscall()) {
 		if (count != sizeof(*compat))
 			return -EINVAL;
 
diff --git a/kernel/time/time.c b/kernel/time/time.c
index e3a7f7fd3abc..ad204cf6d001 100644
--- a/kernel/time/time.c
+++ b/kernel/time/time.c
@@ -842,7 +842,7 @@ int get_timespec64(struct timespec64 *ts,
 	ts->tv_sec = kts.tv_sec;
 
 	/* Zero out the padding for 32 bit systems or in compat mode */
-	if (IS_ENABLED(CONFIG_64BIT_TIME) && (!IS_ENABLED(CONFIG_64BIT) || in_compat_syscall()))
+	if (IS_ENABLED(CONFIG_64BIT_TIME) && in_compat_syscall())
 		kts.tv_nsec &= 0xFFFFFFFFUL;
 
 	ts->tv_nsec = kts.tv_nsec;
diff --git a/net/xfrm/xfrm_state.c b/net/xfrm/xfrm_state.c
index b669262682c9..dc4a9f1fb941 100644
--- a/net/xfrm/xfrm_state.c
+++ b/net/xfrm/xfrm_state.c
@@ -2077,10 +2077,8 @@ int xfrm_user_policy(struct sock *sk, int optname, u8 __user *optval, int optlen
 	struct xfrm_mgr *km;
 	struct xfrm_policy *pol = NULL;
 
-#ifdef CONFIG_COMPAT
 	if (in_compat_syscall())
 		return -EOPNOTSUPP;
-#endif
 
 	if (!optval && !optlen) {
 		xfrm_sk_policy_insert(sk, XFRM_POLICY_IN, NULL);
diff --git a/net/xfrm/xfrm_user.c b/net/xfrm/xfrm_user.c
index ca7a207b81a9..c9a84e22f5d5 100644
--- a/net/xfrm/xfrm_user.c
+++ b/net/xfrm/xfrm_user.c
@@ -2621,10 +2621,8 @@ static int xfrm_user_rcv_msg(struct sk_buff *skb, struct nlmsghdr *nlh,
 	const struct xfrm_link *link;
 	int type, err;
 
-#ifdef CONFIG_COMPAT
 	if (in_compat_syscall())
 		return -EOPNOTSUPP;
-#endif
 
 	type = nlh->nlmsg_type;
 	if (type > XFRM_MSG_MAX)