Re: [PATCH v7 1/2] x86-64: Save APX registers in ld.so trampoline

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

On Fri, Feb 16, 2024 at 12:21 AM H.J. Lu <hjl.tools@gmail.com> wrote:
>
> Add APX registers to STATE_SAVE_MASK so that APX registers are saved in
> ld.so trampoline.  This fixes BZ #31371.
>
> Also update STATE_SAVE_OFFSET and STATE_SAVE_MASK for i386 which will
> be used by i386 _dl_tlsdesc_dynamic.
> ---
>  sysdeps/x86/sysdep.h | 52 +++++++++++++++++++++++++++++++++++++++-----
>  1 file changed, 46 insertions(+), 6 deletions(-)
>
> diff --git a/sysdeps/x86/sysdep.h b/sysdeps/x86/sysdep.h
> index 85d0a8c943..837fd28734 100644
> --- a/sysdeps/x86/sysdep.h
> +++ b/sysdeps/x86/sysdep.h
> @@ -21,14 +21,54 @@
>
>  #include <sysdeps/generic/sysdep.h>
>
> +/* The extended state feature IDs in the state component bitmap.  */
> +#define X86_XSTATE_X87_ID      0
> +#define X86_XSTATE_SSE_ID      1
> +#define X86_XSTATE_AVX_ID      2
> +#define X86_XSTATE_BNDREGS_ID  3
> +#define X86_XSTATE_BNDCFG_ID   4
> +#define X86_XSTATE_K_ID                5
> +#define X86_XSTATE_ZMM_H_ID    6
> +#define X86_XSTATE_ZMM_ID      7
> +#define X86_XSTATE_PKRU_ID     9
> +#define X86_XSTATE_TILECFG_ID  17
> +#define X86_XSTATE_TILEDATA_ID 18
> +#define X86_XSTATE_APX_F_ID    19
> +
> +#ifdef __x86_64__
>  /* Offset for fxsave/xsave area used by _dl_runtime_resolve.  Also need
>     space to preserve RCX, RDX, RSI, RDI, R8, R9 and RAX.  It must be
> -   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.  */
> -#define STATE_SAVE_MASK \
> -  ((1 << 1) | (1 << 2) | (1 << 3) | (1 << 5) | (1 << 6) | (1 << 7))
> +   aligned to 16 bytes for fxsave and 64 bytes for xsave.
> +
> +   NB: Is is non-zero because of the 128-byte red-zone.  Some registers
> +   are saved on stack without adjusting stack pointer first.  When we
> +   update stack pointer to allocate more space, we need to take the
> +   red-zone into account.  */
> +# define STATE_SAVE_OFFSET (8 * 7 + 8)
> +
> +/* Save SSE, AVX, AVX512, mask, bound and APX registers.  Bound and APX
> +   registers are mutually exclusive.  */
> +# define STATE_SAVE_MASK               \
> +  ((1 << X86_XSTATE_SSE_ID)            \
> +   | (1 << X86_XSTATE_AVX_ID)          \
> +   | (1 << X86_XSTATE_BNDREGS_ID)      \
> +   | (1 << X86_XSTATE_K_ID)            \
> +   | (1 << X86_XSTATE_ZMM_H_ID)        \
> +   | (1 << X86_XSTATE_ZMM_ID)          \
> +   | (1 << X86_XSTATE_APX_F_ID))
Need tile here?
> +#else
> +/* Offset for fxsave/xsave area used by _dl_tlsdesc_dynamic.  Since i386
> +   doesn't have red-zone, use 0 here.  */
> +# define STATE_SAVE_OFFSET 0
> +
> +/* Save SSE, AVX, AXV512, mask and bound registers.   */
> +# define STATE_SAVE_MASK               \
> +  ((1 << X86_XSTATE_SSE_ID)            \
> +   | (1 << X86_XSTATE_AVX_ID)          \
> +   | (1 << X86_XSTATE_BNDREGS_ID)      \
> +   | (1 << X86_XSTATE_K_ID)            \
> +   | (1 << X86_XSTATE_ZMM_H_ID))
> +#endif
>
>  /* Constants for bits in __x86_string_control:  */
>
> --
> 2.43.0
>