On Mon, Mar 27, 2023 at 14:15:09 +0200, Ard Biesheuvel wrote:
> On Mon, 27 Mar 2023 at 13:53, Leif Lindholm <quic_llind...@quicinc.com> wrote:
> >
> > On Mon, Mar 27, 2023 at 13:00:56 +0200, Ard Biesheuvel wrote:
> > > Implement a CPP macro that can be called from .S files to emit the .note
> > > section carrying the annotation that informs the linker that the object
> > > file is compatible with BTI control flow integrity checks.
> > >
> > > Signed-off-by: Ard Biesheuvel <a...@kernel.org>
> > > ---
> > > MdePkg/Include/AArch64/ProcessorBind.h | 31 ++++++++++++++++++++
> > > 1 file changed, 31 insertions(+)
> > >
> > > diff --git a/MdePkg/Include/AArch64/ProcessorBind.h
> > > b/MdePkg/Include/AArch64/ProcessorBind.h
> > > index abe2571245c665f3..11814f1ffaef698a 100644
> > > --- a/MdePkg/Include/AArch64/ProcessorBind.h
> > > +++ b/MdePkg/Include/AArch64/ProcessorBind.h
> > > @@ -186,6 +186,37 @@ typedef INT64 INTN;
> > > #define GCC_ASM_IMPORT(func__) \
> > > .extern _CONCATENATE (__USER_LABEL_PREFIX__, func__)
> > >
> > > +#if defined(__ARM_FEATURE_BTI_DEFAULT) && __ARM_FEATURE_BTI_DEFAULT == 1
> > > +#define AARCH64_BTI(__type) \
> > > + .ifnc __type, ;\
> > > + bti __type ;\
> > > + .endif ;\
> > > + .ifndef .Lgnu_bti_notesize ;\
> > > + .pushsection .note.gnu.property, "a" ;\
> > > + .set NT_GNU_PROPERTY_TYPE_0, 0x5 ;\
> > > + .set GNU_PROPERTY_AARCH64_FEATURE_1_AND, 0xc0000000 ;\
> > > + .set GNU_PROPERTY_AARCH64_FEATURE_1_BTI, 0x1 ;\
> > > + .align 3 ;\
> > > + .long .Lnamesize ;\
> > > + .long .Lgnu_bti_notesize ;\
> > > + .long NT_GNU_PROPERTY_TYPE_0 ;\
> > > +0: .asciz "GNU" ;\
> > > + .set .Lnamesize, . - 0b ;\
> > > + .align 3 ;\
> > > +1: .long GNU_PROPERTY_AARCH64_FEATURE_1_AND ;\
> > > + .long .Lvalsize ;\
> > > +2: .long GNU_PROPERTY_AARCH64_FEATURE_1_BTI ;\
> > > + .set .Lvalsize, . - 2b ;\
> > > + .align 3 ;\
> > > + .set .Lgnu_bti_notesize, . - 1b ;\
> > > + .popsection ;\
> > > + .endif
> > > +#endif
> > > +
> > > +#endif
> >
> > Is that second endif superflouous?
> >
>
> No the diff just turned out a bit odd.
Oh, I see - it's because you add this inside the if __GNUC__ || __clang__
and add the #ifndef AARCH64_BTI outside it. Which is necessary. Moving
on.
/
Leif
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