[FFmpeg-devel] [PATCH 2/2] aarch64: Add Armv8.5-A BTI support

Jonathan Wright Jonathan.Wright at arm.com
Tue Nov 16 13:31:49 EET 2021


> +#if (GNU_PROPERTY_AARCH64_BTI != 0)
> +    .pushsection .note.gnu.property, "a";
> +    .balign 8;
> +    .long 4;
> +    .long 0x10;
> +    .long 0x5;
> +    .asciz "GNU";
> +    .long 0xc0000000; /* GNU_PROPERTY_AARCH64_FEATURE_1_AND */
> +    .long 4;
> +    .long GNU_PROPERTY_AARCH64_BTI;
> +    .long 0
> +    .popsection

The trailing semicolons here are superfluous. They'd be needed if stacking
all of it on one single line, but as it's split over multiple lines (which
I like), it's not needed, so I'd suggest removing them.

Also, I'd prefer to have these directives indented in the same way as the
rest of main directives in the file, i.e. with 8 leading spaces.

> +#endif
> +
>  .macro  function name, export=0, align=2
>      .macro endfunc
>  ELF     .size   \name, . - \name
> @@ -49,6 +78,7 @@ FUNC    .endfunc
>  ELF     .type   EXTERN_ASM\name, %function
>  FUNC    .func   EXTERN_ASM\name
>  EXTERN_ASM\name:
> +    AARCH64_VALID_CALL_TARGET
>      .else

I'd also prefer to have this aligned one step deeper, along with the
.size/.type/.func above.

I can make these hopefully innocent changes before pushing, if that's ok
with you. If you want to try out the modifications, my version, ready to
be pushed, is available at
https://github.com/mstorsjo/FFmpeg/commits/aarch64-bti.


Thanks for picking these up, Martin. Your modified version of the change
looks fine to push - no issues when tested on our BTI-enabled test
environment.

Thanks,
Jonathan
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