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?
/
Leif
> +
> +#ifndef AARCH64_BTI
> +#define AARCH64_BTI(__type)
> #endif
>
> /**
> --
> 2.39.2
>
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