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 <[email protected]>
Cc: Thomas Bogendoerfer <[email protected]>
Cc: Marc Zyngier <[email protected]>
Cc: Guenter Roeck <[email protected]>
Cc: Yanteng Si <[email protected]>
Cc: [email protected]
Signed-off-by: Kees Cook <[email protected]>
---
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..15769013f46e 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 >= 150000
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
Nit: I think the subject needs to be updated (I assume this was written
before Nick's fix?).
On Wed, Mar 09, 2022 at 12:45:37PM -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 <[email protected]>
> Cc: Thomas Bogendoerfer <[email protected]>
> Cc: Marc Zyngier <[email protected]>
> Cc: Guenter Roeck <[email protected]>
> Cc: Yanteng Si <[email protected]>
> Cc: [email protected]
> Signed-off-by: Kees Cook <[email protected]>
Thanks for sending this!
Reviewed-by: Nathan Chancellor <[email protected]>
> ---
> 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..15769013f46e 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 >= 150000
Nit: This can be 140000, as release/14.x has received the fix:
https://github.com/llvm/llvm-project/commit/0826716786cd4a8c7cbcb8c01e4d9fac46b7a17a
> 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
>
On Wed, Mar 09, 2022 at 01:51:13PM -0700, Nathan Chancellor wrote:
> Nit: I think the subject needs to be updated (I assume this was written
> before Nick's fix?).
>
> On Wed, Mar 09, 2022 at 12:45:37PM -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 <[email protected]>
> > Cc: Thomas Bogendoerfer <[email protected]>
> > Cc: Marc Zyngier <[email protected]>
> > Cc: Guenter Roeck <[email protected]>
> > Cc: Yanteng Si <[email protected]>
> > Cc: [email protected]
> > Signed-off-by: Kees Cook <[email protected]>
>
> Thanks for sending this!
>
> Reviewed-by: Nathan Chancellor <[email protected]>
>
> > ---
> > 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..15769013f46e 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 >= 150000
>
> Nit: This can be 140000, as release/14.x has received the fix:
>
> https://github.com/llvm/llvm-project/commit/0826716786cd4a8c7cbcb8c01e4d9fac46b7a17a
Oh! Excellent. Thanks; I missed that it made the branch. I'll send a v2.
--
Kees Cook