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SubjectRe: [RFC v5 47/57] arm64: assembler: Add macro to annotate asm function having non standard stack-frame.
On Thu, Jan 23, 2020 at 01:45:58PM +0000, Julien Thierry wrote:
> On 1/21/20 10:30 AM, Will Deacon wrote:
> > On Thu, Jan 09, 2020 at 04:02:50PM +0000, Julien Thierry wrote:
> > > From: Raphael Gault <raphael.gault@arm.com>
> > > diff --git a/include/linux/frame.h b/include/linux/frame.h
> > > index 02d3ca2d9598..1e35e58ab259 100644
> > > --- a/include/linux/frame.h
> > > +++ b/include/linux/frame.h
> > > @@ -11,14 +11,31 @@
> > > *
> > > * For more information, see tools/objtool/Documentation/stack-validation.txt.
> > > */
> > > +#ifndef __ASSEMBLY__
> > > #define STACK_FRAME_NON_STANDARD(func) \
> > > static void __used __section(.discard.func_stack_frame_non_standard) \
> > > *__func_stack_frame_non_standard_##func = func
> > > +#else
> > > + /*
> > > + * This macro is the arm64 assembler equivalent of the
> > > + * macro STACK_FRAME_NON_STANDARD define at
> > > + * ~/include/linux/frame.h
> > > + */
> > > + .macro asm_stack_frame_non_standard func
> > > + .pushsection ".discard.func_stack_frame_non_standard"
> > > + .quad \func
> > > + .popsection
> > > + .endm
> > >
> > > +#endif /* __ASSEMBLY__ */
> > > #else /* !CONFIG_STACK_VALIDATION */
> > >
> > > +#ifndef __ASSEMBLY__
> > > #define STACK_FRAME_NON_STANDARD(func)
> > > -
> > > +#else
> > > + .macro asm_stack_frame_non_standard func
> > > + .endm
> > > +#endif /* __ASSEMBLY__ */
> >
> > Hmm. Given that we're currently going through the exercise of converting
> > a bunch of ENTRY/ENDPROC macros to use the new SYM_{CODE,FUNC}_{START,END}
> > macros, I would much prefer for this to be a new flavour of those.
> >
> > In fact, can you just use SYM_CODE_* for this?
> >
>
> You mean to not introduce the STACK_FRAME_NON_STANDARD() macro and just mark
> the asm callable symbols that don't set up a stackframe as SYM_CODE_* ?

Yes, unless I'm mistaken, SYM_CODE_* is intended for that sort of thing
anyway.

Will

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