* [PATCH v2] MIPS: Only use current_stack_pointer on GCC
@ 2022-03-09 22:09 Kees Cook
2022-03-09 22:44 ` David Laight
2022-03-14 14:52 ` Thomas Bogendoerfer
0 siblings, 2 replies; 5+ messages in thread
From: Kees Cook @ 2022-03-09 22:09 UTC (permalink / raw)
To: Thomas Bogendoerfer
Cc: Kees Cook, Nathan Chancellor, Marc Zyngier, Guenter Roeck,
Yanteng Si, linux-mips, Nick Desaulniers, Mark Rutland,
linux-kernel, llvm, linux-hardening
Unfortunately, Clang did not have support for "sp" as a global register
definition, and was crashing after the addition of current_stack_pointer.
This has been fixed in Clang 15, but earlier Clang versions need to
avoid this code, so add a versioned test and revert back to the
open-coded asm instances. Fixes Clang build error:
fatal error: error in backend: Invalid register name global variable
Fixes: 200ed341b864 ("mips: Implement "current_stack_pointer"")
Reported-by: Nathan Chancellor <nathan@kernel.org>
Reviewed-by: Nathan Chancellor <nathan@kernel.org>
Link: https://lore.kernel.org/lkml/YikTQRql+il3HbrK@dev-arch.thelio-3990X
Cc: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
Cc: Marc Zyngier <maz@kernel.org>
Cc: Guenter Roeck <linux@roeck-us.net>
Cc: Yanteng Si <siyanteng01@gmail.com>
Cc: linux-mips@vger.kernel.org
Signed-off-by: Kees Cook <keescook@chromium.org>
---
v1: https://lore.kernel.org/lkml/20220309204537.390428-1-keescook@chromium.org
v2: - adjust Clang version (Nathan)
---
arch/mips/Kconfig | 2 +-
arch/mips/include/asm/thread_info.h | 2 ++
arch/mips/kernel/irq.c | 3 ++-
arch/mips/lib/uncached.c | 4 +++-
4 files changed, 8 insertions(+), 3 deletions(-)
diff --git a/arch/mips/Kconfig b/arch/mips/Kconfig
index 3f58b45fc953..0dae5f1e61cc 100644
--- a/arch/mips/Kconfig
+++ b/arch/mips/Kconfig
@@ -4,7 +4,7 @@ config MIPS
default y
select ARCH_32BIT_OFF_T if !64BIT
select ARCH_BINFMT_ELF_STATE if MIPS_FP_SUPPORT
- select ARCH_HAS_CURRENT_STACK_POINTER
+ select ARCH_HAS_CURRENT_STACK_POINTER if !CC_IS_CLANG || CLANG_VERSION >= 140000
select ARCH_HAS_DEBUG_VIRTUAL if !64BIT
select ARCH_HAS_FORTIFY_SOURCE
select ARCH_HAS_KCOV
diff --git a/arch/mips/include/asm/thread_info.h b/arch/mips/include/asm/thread_info.h
index 4463348d2372..ecae7470faa4 100644
--- a/arch/mips/include/asm/thread_info.h
+++ b/arch/mips/include/asm/thread_info.h
@@ -69,7 +69,9 @@ static inline struct thread_info *current_thread_info(void)
return __current_thread_info;
}
+#ifdef CONFIG_ARCH_HAS_CURRENT_STACK_POINTER
register unsigned long current_stack_pointer __asm__("sp");
+#endif
#endif /* !__ASSEMBLY__ */
diff --git a/arch/mips/kernel/irq.c b/arch/mips/kernel/irq.c
index fc313c49a417..5e11582fe308 100644
--- a/arch/mips/kernel/irq.c
+++ b/arch/mips/kernel/irq.c
@@ -75,8 +75,9 @@ void __init init_IRQ(void)
#ifdef CONFIG_DEBUG_STACKOVERFLOW
static inline void check_stack_overflow(void)
{
- unsigned long sp = current_stack_pointer;
+ unsigned long sp;
+ __asm__ __volatile__("move %0, $sp" : "=r" (sp));
sp &= THREAD_MASK;
/*
diff --git a/arch/mips/lib/uncached.c b/arch/mips/lib/uncached.c
index f8d4ca046c3e..f80a67c092b6 100644
--- a/arch/mips/lib/uncached.c
+++ b/arch/mips/lib/uncached.c
@@ -40,7 +40,9 @@ unsigned long run_uncached(void *func)
register long ret __asm__("$2");
long lfunc = (long)func, ufunc;
long usp;
- long sp = current_stack_pointer;
+ long sp;
+
+ __asm__("move %0, $sp" : "=r" (sp));
if (sp >= (long)CKSEG0 && sp < (long)CKSEG2)
usp = CKSEG1ADDR(sp);
--
2.32.0
^ permalink raw reply related [flat|nested] 5+ messages in thread
* RE: [PATCH v2] MIPS: Only use current_stack_pointer on GCC
2022-03-09 22:09 [PATCH v2] MIPS: Only use current_stack_pointer on GCC Kees Cook
@ 2022-03-09 22:44 ` David Laight
2022-03-10 18:20 ` Nick Desaulniers
2022-03-14 14:52 ` Thomas Bogendoerfer
1 sibling, 1 reply; 5+ messages in thread
From: David Laight @ 2022-03-09 22:44 UTC (permalink / raw)
To: 'Kees Cook', Thomas Bogendoerfer
Cc: Nathan Chancellor, Marc Zyngier, Guenter Roeck, Yanteng Si,
linux-mips, Nick Desaulniers, Mark Rutland, linux-kernel, llvm,
linux-hardening
From: Kees Cook
> Sent: 09 March 2022 22:10
>
> Unfortunately, Clang did not have support for "sp" as a global register
> definition, and was crashing after the addition of current_stack_pointer.
> This has been fixed in Clang 15, but earlier Clang versions need to
^^ 14
> avoid this code, so add a versioned test and revert back to the
> open-coded asm instances. Fixes Clang build error:
>
> fatal error: error in backend: Invalid register name global variable
David
-
Registered Address Lakeside, Bramley Road, Mount Farm, Milton Keynes, MK1 1PT, UK
Registration No: 1397386 (Wales)
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [PATCH v2] MIPS: Only use current_stack_pointer on GCC
2022-03-09 22:44 ` David Laight
@ 2022-03-10 18:20 ` Nick Desaulniers
0 siblings, 0 replies; 5+ messages in thread
From: Nick Desaulniers @ 2022-03-10 18:20 UTC (permalink / raw)
To: David Laight, Kees Cook
Cc: Thomas Bogendoerfer, Nathan Chancellor, Marc Zyngier,
Guenter Roeck, Yanteng Si, linux-mips, Mark Rutland,
linux-kernel, llvm, linux-hardening
On Wed, Mar 9, 2022 at 2:44 PM David Laight <David.Laight@aculab.com> wrote:
>
> From: Kees Cook
> > Sent: 09 March 2022 22:10
> >
> > Unfortunately, Clang did not have support for "sp" as a global register
> > definition, and was crashing after the addition of current_stack_pointer.
> > This has been fixed in Clang 15, but earlier Clang versions need to
> ^^ 14
Yeah, with that fixed:
Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
Once clang-14 is the minimally supported version, we can go back to
removing the inline asm for everyone.
> > avoid this code, so add a versioned test and revert back to the
> > open-coded asm instances. Fixes Clang build error:
> >
> > fatal error: error in backend: Invalid register name global variable
>
> David
>
> -
> Registered Address Lakeside, Bramley Road, Mount Farm, Milton Keynes, MK1 1PT, UK
> Registration No: 1397386 (Wales)
>
--
Thanks,
~Nick Desaulniers
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [PATCH v2] MIPS: Only use current_stack_pointer on GCC
2022-03-09 22:09 [PATCH v2] MIPS: Only use current_stack_pointer on GCC Kees Cook
2022-03-09 22:44 ` David Laight
@ 2022-03-14 14:52 ` Thomas Bogendoerfer
2022-03-15 18:09 ` Kees Cook
1 sibling, 1 reply; 5+ messages in thread
From: Thomas Bogendoerfer @ 2022-03-14 14:52 UTC (permalink / raw)
To: Kees Cook
Cc: Nathan Chancellor, Marc Zyngier, Guenter Roeck, Yanteng Si,
linux-mips, Nick Desaulniers, Mark Rutland, linux-kernel, llvm,
linux-hardening
On Wed, Mar 09, 2022 at 02:09:39PM -0800, Kees Cook wrote:
> Unfortunately, Clang did not have support for "sp" as a global register
> definition, and was crashing after the addition of current_stack_pointer.
> This has been fixed in Clang 15, but earlier Clang versions need to
> avoid this code, so add a versioned test and revert back to the
> open-coded asm instances. Fixes Clang build error:
>
> fatal error: error in backend: Invalid register name global variable
>
> Fixes: 200ed341b864 ("mips: Implement "current_stack_pointer"")
> Reported-by: Nathan Chancellor <nathan@kernel.org>
> Reviewed-by: Nathan Chancellor <nathan@kernel.org>
> Link: https://lore.kernel.org/lkml/YikTQRql+il3HbrK@dev-arch.thelio-3990X
> Cc: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
> Cc: Marc Zyngier <maz@kernel.org>
> Cc: Guenter Roeck <linux@roeck-us.net>
> Cc: Yanteng Si <siyanteng01@gmail.com>
> Cc: linux-mips@vger.kernel.org
> Signed-off-by: Kees Cook <keescook@chromium.org>
> ---
> v1: https://lore.kernel.org/lkml/20220309204537.390428-1-keescook@chromium.org
> v2: - adjust Clang version (Nathan)
> ---
> arch/mips/Kconfig | 2 +-
> arch/mips/include/asm/thread_info.h | 2 ++
> arch/mips/kernel/irq.c | 3 ++-
> arch/mips/lib/uncached.c | 4 +++-
> 4 files changed, 8 insertions(+), 3 deletions(-)
applied to mips-next with the Clang version in the decscription fixed.
Thomas.
--
Crap can work. Given enough thrust pigs will fly, but it's not necessarily a
good idea. [ RFC1925, 2.3 ]
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [PATCH v2] MIPS: Only use current_stack_pointer on GCC
2022-03-14 14:52 ` Thomas Bogendoerfer
@ 2022-03-15 18:09 ` Kees Cook
0 siblings, 0 replies; 5+ messages in thread
From: Kees Cook @ 2022-03-15 18:09 UTC (permalink / raw)
To: Thomas Bogendoerfer
Cc: Nathan Chancellor, Marc Zyngier, Guenter Roeck, Yanteng Si,
linux-mips, Nick Desaulniers, Mark Rutland, linux-kernel, llvm,
linux-hardening
On Mon, Mar 14, 2022 at 03:52:15PM +0100, Thomas Bogendoerfer wrote:
> On Wed, Mar 09, 2022 at 02:09:39PM -0800, Kees Cook wrote:
> > Unfortunately, Clang did not have support for "sp" as a global register
> > definition, and was crashing after the addition of current_stack_pointer.
> > This has been fixed in Clang 15, but earlier Clang versions need to
> > avoid this code, so add a versioned test and revert back to the
> > open-coded asm instances. Fixes Clang build error:
> >
> > fatal error: error in backend: Invalid register name global variable
> >
> > Fixes: 200ed341b864 ("mips: Implement "current_stack_pointer"")
> > Reported-by: Nathan Chancellor <nathan@kernel.org>
> > Reviewed-by: Nathan Chancellor <nathan@kernel.org>
> > Link: https://lore.kernel.org/lkml/YikTQRql+il3HbrK@dev-arch.thelio-3990X
> > Cc: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
> > Cc: Marc Zyngier <maz@kernel.org>
> > Cc: Guenter Roeck <linux@roeck-us.net>
> > Cc: Yanteng Si <siyanteng01@gmail.com>
> > Cc: linux-mips@vger.kernel.org
> > Signed-off-by: Kees Cook <keescook@chromium.org>
> > ---
> > v1: https://lore.kernel.org/lkml/20220309204537.390428-1-keescook@chromium.org
> > v2: - adjust Clang version (Nathan)
> > ---
> > arch/mips/Kconfig | 2 +-
> > arch/mips/include/asm/thread_info.h | 2 ++
> > arch/mips/kernel/irq.c | 3 ++-
> > arch/mips/lib/uncached.c | 4 +++-
> > 4 files changed, 8 insertions(+), 3 deletions(-)
>
> applied to mips-next with the Clang version in the decscription fixed.
Excellent; thanks very much!
-Kees
--
Kees Cook
^ permalink raw reply [flat|nested] 5+ messages in thread
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2022-03-09 22:09 [PATCH v2] MIPS: Only use current_stack_pointer on GCC Kees Cook
2022-03-09 22:44 ` David Laight
2022-03-10 18:20 ` Nick Desaulniers
2022-03-14 14:52 ` Thomas Bogendoerfer
2022-03-15 18:09 ` Kees Cook
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