Re: [PATCH] ntdll: Reserve space for the whole 64-bit YMM context in struct x86_thread_data.

[Zhiyi Zhang]

Wine-Bug: https://bugs.winehq.org/show_bug.cgi?id=51262

On 6/12/21 3:11 PM, Zebediah Figura wrote:
> Fixes a regression introduced by 308a5e7c4d01525184b057058949c68c0ee77dba.
>
> This was previously broken, but happened to work until the aforementioned
> commit put the YMM state right at the end of a page.
> Signed-off-by: Zebediah Figura
>
> I don't know how accurate "some" is; both of my development machines suffer from
> this. It manifests as a stack overflow trying to execute any 32-bit program. The
> processors in question are AMD cores manufactured in 2012 and 2018.
>
> dlls/ntdll/unix/signal_i386.c | 53 +++++++++++------------------------
>  1 file changed, 16 insertions(+), 37 deletions(-)
>
> diff --git a/dlls/ntdll/unix/signal_i386.c b/dlls/ntdll/unix/signal_i386.c
> index 0b2b269505f..446fed25eb8 100644
> --- a/dlls/ntdll/unix/signal_i386.c
> +++ b/dlls/ntdll/unix/signal_i386.c
> @@ -461,24 +461,6 @@ enum i386_trap_code
>  #endif
>  };
>
> -struct syscall_xsave
> -{
> - union
> - {
> -
>    XSAVE_FORMAT       xsave;
> -
>    FLOATING_SAVE_AREA fsave;
> - } u;
> - struct
> - {
> -
>    ULONG64 mask;
> -
>    ULONG64 compaction_mask;
> -
>    ULONG64 reserved[6];
> -
>    M128A   ymm_high[8];
> - } xstate;
>
> -};
> -
>
> -C_ASSERT( sizeof(struct syscall_xsave) == 0x2c0 );
> -
>
> struct syscall_frame
>  {
>      DWORD              restore_flags;  /* 000 */
> @@ -504,16 +486,13 @@ struct syscall_frame
>          XSAVE_FORMAT       xsave;
>          FLOATING_SAVE_AREA fsave;
>      } u;
> - struct                            /* 240 */
> - {
> -
>    ULONG64 mask;
> -
>    ULONG64 compaction_mask;
> -
>    ULONG64 reserved[6];
> -
>    M128A   ymm_high[8];
> - } xstate;
> - /* Leave space for the whole set of YMM registers. They're not used in
> -
> * 32-bit mode, but some processors fault if they're not in writable memory.
> -
> */
> - XSTATE             xstate;         /* 240 */
>
> };
>
> -C_ASSERT( sizeof(struct syscall_frame) == 0x300 );
> +C_ASSERT( sizeof(struct syscall_frame) == 0x380 );
>
> struct x86_thread_data
>  {
> @@ -1011,7 +990,7 @@ NTSTATUS WINAPI NtSetContextThread( HANDLE handle, const CONTEXT *context )
>          memcpy( &frame->u.xsave, context->ExtendedRegisters, sizeof(frame->u.xsave) );
>          /* reset the current interrupt status */
>          frame->u.xsave.StatusWord &= frame->u.xsave.ControlWord | 0xff80;
> -
>    frame->xstate.mask |= XSTATE_MASK_LEGACY;
> -
>    frame->xstate.Mask |= XSTATE_MASK_LEGACY;
> }
>    else if (flags & CONTEXT_FLOATING_POINT)
>    {
>
> @@ -1023,7 +1002,7 @@ NTSTATUS WINAPI NtSetContextThread( HANDLE handle, const CONTEXT *context )
>          {
>              frame->u.fsave = context->FloatSave;
>          }
> -
>    frame->xstate.mask |= XSTATE_MASK_LEGACY_FLOATING_POINT;
> -
>    frame->xstate.Mask |= XSTATE_MASK_LEGACY_FLOATING_POINT;
> }
>    if (flags & CONTEXT_XSTATE)
>    {
>
> @@ -1032,10 +1011,10 @@ NTSTATUS WINAPI NtSetContextThread( HANDLE handle, const CONTEXT *context )
>      if (xs->Mask & XSTATE_MASK_GSSE)
>      {
> -
>        frame->xstate.mask |= XSTATE_MASK_GSSE;
> -
>        memcpy( &frame->xstate.ymm_high, &xs->YmmContext, sizeof(frame->xstate.ymm_high) );
> -
>        frame->xstate.Mask |= XSTATE_MASK_GSSE;
> -
>        frame->xstate.YmmContext = xs->YmmContext;
>    }
> -
>    else frame->xstate.mask &= ~XSTATE_MASK_GSSE;
> -
>    else frame->xstate.Mask &= ~XSTATE_MASK_GSSE;
>
> }
>
> frame->restore_flags |= flags & ~CONTEXT_INTEGER;
>
> @@ -1104,7 +1083,7 @@ NTSTATUS WINAPI NtGetContextThread( HANDLE handle, CONTEXT *context )
>                  context->FloatSave = frame->u.fsave;
>              }
>              else if (!xstate_compaction_enabled ||
> -
>                 (frame->xstate.mask & XSTATE_MASK_LEGACY_FLOATING_POINT))
> -
>                 (frame->xstate.Mask & XSTATE_MASK_LEGACY_FLOATING_POINT))
>        {
>            fpux_to_fpu( &context->FloatSave, &frame->u.xsave );
>        }
>
> @@ -1120,7 +1099,7 @@ NTSTATUS WINAPI NtGetContextThread( HANDLE handle, CONTEXT *context )
>              XSAVE_FORMAT *xs = (XSAVE_FORMAT *)context->ExtendedRegisters;
>          if (!xstate_compaction_enabled ||
> -
>            (frame->xstate.mask & XSTATE_MASK_LEGACY_FLOATING_POINT))
> -
>            (frame->xstate.Mask & XSTATE_MASK_LEGACY_FLOATING_POINT))
>        {
>            memcpy( xs, &frame->u.xsave, FIELD_OFFSET( XSAVE_FORMAT, MxCsr ));
>            memcpy( xs->FloatRegisters, frame->u.xsave.FloatRegisters,
>
> @@ -1133,7 +1112,7 @@ NTSTATUS WINAPI NtGetContextThread( HANDLE handle, CONTEXT *context )
>                  xs->ControlWord = 0x37f;
>              }
> -
>        if (!xstate_compaction_enabled || (frame->xstate.mask & XSTATE_MASK_LEGACY_SSE))
> -
>        if (!xstate_compaction_enabled || (frame->xstate.Mask & XSTATE_MASK_LEGACY_SSE))
>        {
>            memcpy( xs->XmmRegisters, frame->u.xsave.XmmRegisters, sizeof( xs->XmmRegisters ));
>            xs->MxCsr      = frame->u.xsave.MxCsr;
>
> @@ -1168,7 +1147,7 @@ NTSTATUS WINAPI NtGetContextThread( HANDLE handle, CONTEXT *context )
>                  return STATUS_INVALID_PARAMETER;
>          mask = (xstate_compaction_enabled ? xstate->CompactionMask : xstate->Mask) & XSTATE_MASK_GSSE;
> -
>        xstate->Mask = frame->xstate.mask & mask;
> -
>        xstate->Mask = frame->xstate.Mask & mask;
>        xstate->CompactionMask = xstate_compaction_enabled ? (0x8000000000000000 | mask) : 0;
>        memset( xstate->Reserved, 0, sizeof(xstate->Reserved) );
>        if (xstate->Mask)
>
> @@ -1176,7 +1155,7 @@ NTSTATUS WINAPI NtGetContextThread( HANDLE handle, CONTEXT *context )
>                  if (context_ex->XState.Length < sizeof(XSTATE))
>                      return STATUS_BUFFER_OVERFLOW;
> -
>            memcpy( &xstate->YmmContext, frame->xstate.ymm_high, sizeof(frame->xstate.ymm_high) );
> -
>            xstate->YmmContext = frame->xstate.YmmContext;
>        }
>    }
> }
>
> @@ -2401,7 +2380,7 @@ __ASM_GLOBAL_FUNC( signal_start_thread,
>                     /* set syscall frame */
>                     "cmpl $0,%fs:0x1f8\n\t"      /* x86_thread_data()->syscall_frame */
>                     "jnz 1f\n\t"
> -
>               "leal -0x300(%esp),%eax\n\t" /* sizeof(struct syscall_frame) */
> -
>               "leal -0x380(%esp),%eax\n\t" /* sizeof(struct syscall_frame) */
>               "andl $~63,%eax\n\t"
>               "movl %eax,%fs:0x1f8\n"      /* x86_thread_data()->syscall_frame */
>               /* switch to thread stack */