Re: [PATCH] x86-64: Save APX registers in ld.so trampoline

[Noah Goldstein <goldstein.w.n@gmail.com>]

On Mon, Feb 12, 2024 at 12:46 AM H.J. Lu <hjl.tools@gmail.com> wrote:
>
> Remove bound registers from STATE_SAVE_MASK and add APX registers to
> STATE_SAVE_MASK so that APX registers are saved in ld.so trampoline.
> This fixes BZ #31371.
> ---
>  sysdeps/x86/sysdep.h | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/sysdeps/x86/sysdep.h b/sysdeps/x86/sysdep.h
> index 85d0a8c943..9877a3a46f 100644
> --- a/sysdeps/x86/sysdep.h
> +++ b/sysdeps/x86/sysdep.h
> @@ -26,9 +26,9 @@
>     aligned to 16 bytes for fxsave and 64 bytes for xsave.  */
>  #define STATE_SAVE_OFFSET (8 * 7 + 8)
>
> -/* Save SSE, AVX, AVX512, mask and bound registers.  */
> +/* Save SSE, AVX, AVX512, mask and APX registers.  */
>  #define STATE_SAVE_MASK \
> -  ((1 << 1) | (1 << 2) | (1 << 3) | (1 << 5) | (1 << 6) | (1 << 7))
> +  ((1 << 1) | (1 << 2) | (1 << 5) | (1 << 6) | (1 << 7) | (1 << 19))

Not 100% necessary for this patch, but defines for which bit
is associated with which state would probably make this easier
to maintain.

I.e
#define STATE_BIT_FP        (1 << 0)
#define STATE_BIT_SSE       (1 << 1)
#define STATE_BIT_YMM       (1 << 2)
#define STATE_BIT_BNDREGS   (1 << 3)
#define STATE_BIT_BNDCSR    (1 << 4)
#define STATE_BIT_OPMASK    (1 << 5)
#define STATE_BIT_ZMM_Hi256 (1 << 6)
#define STATE_BIT_Hi16_ZMM  (1 << 7)
#define STATE_BIT_APX       (1 << 19)

#define STATE_SAVE_MASK (STATE_BIT_FP | STATE_BIT_SSE | ...)
>
>  /* Constants for bits in __x86_string_control:  */
>
> --
> 2.43.0
>