ntdll: Use syscall frame for x86_64 YMM context in NtGetContextThread.

dlls/ntdll/unix/signal_x86_64.c

@@ -1541,56 +1541,6 @@ static void save_context( struct xcontext *xcontext, const ucontext_t *sigcontex
 
 
 /***********************************************************************
- *           save_xstate
- *
- * Save the XState context
- */
-static inline NTSTATUS save_xstate( CONTEXT *context )
-{
-    CONTEXT_EX *context_ex = (CONTEXT_EX *)(context + 1);
-    DECLSPEC_ALIGN(64) struct
-    {
-        XSAVE_FORMAT xsave;
-        XSTATE xstate;
-    }
-    xsave_area;
-    XSTATE *xs;
-
-    if (!(user_shared_data->XState.EnabledFeatures && (xs = xstate_from_context( context ))))
-        return STATUS_SUCCESS;
-
-    if (context_ex->XState.Length < offsetof(XSTATE, YmmContext)
-            || context_ex->XState.Length > sizeof(XSTATE))
-        return STATUS_INVALID_PARAMETER;
-
-    if (user_shared_data->XState.CompactionEnabled)
-    {
-        /* xsavec doesn't use anything from the save area. */
-        __asm__ volatile( "xsavec %0" : "=m"(xsave_area)
-                : "a" ((unsigned int)(xs->CompactionMask & (1 << XSTATE_AVX))), "d" (0) );
-    }
-    else
-    {
-        /* xsave preserves those bits in the mask which are not in EDX:EAX, so zero it. */
-        xsave_area.xstate.Mask = xsave_area.xstate.CompactionMask = 0;
-        __asm__ volatile( "xsave %0" : "=m"(xsave_area)
-                : "a" ((unsigned int)(xs->Mask & (1 << XSTATE_AVX))), "d" (0) );
-    }
-
-    memcpy(xs, &xsave_area.xstate, offsetof(XSTATE, YmmContext));
-    if (xs->Mask & (1 << XSTATE_AVX))
-    {
-        if (context_ex->XState.Length < sizeof(XSTATE))
-            return STATUS_BUFFER_OVERFLOW;
-
-        memcpy(&xs->YmmContext, &xsave_area.xstate.YmmContext, sizeof(xs->YmmContext));
-    }
-
-    return STATUS_SUCCESS;
-}
-
-
-/***********************************************************************
  *           restore_context
  *
  * Build a sigcontext from the register values.
@@ -1895,17 +1845,14 @@ NTSTATUS WINAPI NtSetContextThread( HANDLE handle, const CONTEXT *context )
  */
 NTSTATUS WINAPI NtGetContextThread( HANDLE handle, CONTEXT *context )
 {
-    NTSTATUS ret, xsave_status;
+    NTSTATUS ret;
     DWORD needed_flags;
     struct syscall_frame *frame = amd64_thread_data()->syscall_frame;
     BOOL self = (handle == GetCurrentThread());
+    XSTATE *xstate;
 
     if (!context) return STATUS_INVALID_PARAMETER;
 
-    /* Save xstate before any calls which can potentially change volatile ymm registers.
-     * E. g., debug output will clobber ymm registers. */
-    xsave_status = self ? save_xstate( context ) : STATUS_SUCCESS;
-
     needed_flags = context->ContextFlags & ~CONTEXT_AMD64;
 
     /* debug registers require a server call */
@@ -1975,9 +1922,32 @@ NTSTATUS WINAPI NtGetContextThread( HANDLE handle, CONTEXT *context )
             amd64_thread_data()->dr6 = context->Dr6;
             amd64_thread_data()->dr7 = context->Dr7;
         }
+        if (user_shared_data->XState.EnabledFeatures && (xstate = xstate_from_context( context )))
+        {
+            struct syscall_xsave *xsave = get_syscall_xsave( frame );
+            CONTEXT_EX *context_ex = (CONTEXT_EX *)(context + 1);
+            const BOOL compaction_enabled = user_shared_data->XState.CompactionEnabled;
+            unsigned int mask;
+
+            if (context_ex->XState.Length < offsetof(XSTATE, YmmContext)
+                || context_ex->XState.Length > sizeof(XSTATE))
+                return STATUS_INVALID_PARAMETER;
+
+            mask = (compaction_enabled ? xstate->CompactionMask : xstate->Mask) & XSTATE_MASK_GSSE;
+            xstate->Mask = xsave->xstate.Mask & mask;
+            xstate->CompactionMask = compaction_enabled ? (0x8000000000000000 | mask) : 0;
+            memset( xstate->Reserved, 0, sizeof(xstate->Reserved) );
+            if (xstate->Mask)
+            {
+                if (context_ex->XState.Length < sizeof(XSTATE))
+                    return STATUS_BUFFER_OVERFLOW;
+
+                memcpy( &xstate->YmmContext, &xsave->xstate.YmmContext, sizeof(xstate->YmmContext) );
+            }
+        }
     }
 
-    return xsave_status;
+    return STATUS_SUCCESS;
 }
 
 extern void CDECL raise_func_trampoline( void *dispatcher );