[FFmpeg-devel] [PATCH] arm64: Add Armv8.3-A PAC support to assembly files

[Martin Storsjö]

On Mon, 14 Feb 2022, Andre Kempe wrote:

> This patch adds optional support for Arm Pointer Authentication Codes.
>
> PAC support is turned on or off at compile time using additional
> compiler flags. Unless any of these is enabled explicitly, no additional
> code will be emitted at all.
>
> Signed-off-by: André Kempe <andre.kempe at arm.com>
> ---
> libavcodec/aarch64/fft_neon.S          |   3 +-
> libavcodec/aarch64/mdct_neon.S         |  17 ++++-
> libavcodec/aarch64/synth_filter_neon.S |   2 +
> libavutil/aarch64/asm.S                | 102 +++++++++++++++++++++++--
> 4 files changed, 113 insertions(+), 11 deletions(-)

LGTM, this looks generally correct and consistent to me.

But I realized one thing (which probably should be fixed both here and in 
dav1d, but which I guess we can fix separately afterwards too) - I guess 
we should only output the .note.gnu.property section if we're targeting 
ELF. (I guess that PAC/BTI aren't used on other platforms yet, but it's 
plausible that they will be, and then they won't use ELF note sections to 
signal it.)

// Martin