Re: [PATCH 01/16] powerpc: Replace unreachable() with it's builtin variant in WARN_ON()

[Sathvika Vasireddy]

Hi Christophe,

On 26/08/22 15:48, Christophe Leroy wrote:
> Le 08/08/2022 à 13:48, Sathvika Vasireddy a écrit :
> > objtool is throwing *unannotated intra-function call*
> > warnings with a few instructions that are marked
> > unreachable. Replace unreachable() with __builtin_unreachable()
> > to fix these warnings, as the codegen remains same
> > with unreachable() and __builtin_unreachable().
> >
> > Signed-off-by: Sathvika Vasireddy <sv@xxxxxxxxxxxxx>
> > ---
> >    arch/powerpc/include/asm/bug.h | 2 +-
> >    1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/arch/powerpc/include/asm/bug.h b/arch/powerpc/include/asm/bug.h
> > index 61a4736355c2..074be1a78c56 100644
> > --- a/arch/powerpc/include/asm/bug.h
> > +++ b/arch/powerpc/include/asm/bug.h
> > @@ -99,7 +99,7 @@
> >    	__label__ __label_warn_on;				\
> >    								\
> >    	WARN_ENTRY("twi 31, 0, 0", BUGFLAG_WARNING | (flags), __label_warn_on); \
> > -	unreachable();						\
> > +	__builtin_unreachable();				\
> Should you add barrier_before_unreachable() before
> __builtin_unreachable() to avoid stack bombs ?
>
> See commit 173a3efd3edb ("bug.h: work around GCC PR82365 in BUG()")

Yes, adding barrier_before_unreachable() before __builtin_unreachable()

works around the build issues reported at 
https://lkml.org/lkml/2022/8/25/418.

I'll post a v2 with this change.

Thanks for the suggestion!

- Sathvika