x86emul: all push flavors are data moves

Make all paths leading to the "push" label have the Mov flag set, and
ASSERT() that to be the case. For the opcode FF group the adjustment is
benign for the paths not leading to "push", as they all set dst.type to
OP_NONE

Signed-off-by: Jan Beulich <jbeulich@suse.com>

--- a/xen/arch/x86/x86_emulate/x86_emulate.c
+++ b/xen/arch/x86/x86_emulate/x86_emulate.c
@@ -122,7 +122,7 @@ static uint8_t opcode_table[256] = {
     ImplicitOps, ImplicitOps, ImplicitOps, ImplicitOps,
     /* 0x98 - 0x9F */
     ImplicitOps, ImplicitOps, ImplicitOps, ImplicitOps,
-    ImplicitOps, ImplicitOps, ImplicitOps, ImplicitOps,
+    ImplicitOps|Mov, ImplicitOps|Mov, ImplicitOps, ImplicitOps,
     /* 0xA0 - 0xA7 */
     ByteOp|ImplicitOps|Mov, ImplicitOps|Mov,
     ByteOp|ImplicitOps|Mov, ImplicitOps|Mov,
@@ -1903,7 +1903,7 @@ x86_emulate(
                 /* fall through */
             case 3: /* call (far, absolute indirect) */
             case 5: /* jmp (far, absolute indirect) */
-                d = DstNone|SrcMem|ModRM;
+                d = DstNone | SrcMem | ModRM | Mov;
                 break;
             }
             break;
@@ -2347,7 +2347,7 @@ x86_emulate(
     case 0x68: /* push imm{16,32,64} */
     case 0x6a: /* push imm8 */
     push:
-        d |= Mov; /* force writeback */
+        ASSERT(d & Mov); /* writeback needed */
         dst.type  = OP_MEM;
         dst.bytes = mode_64bit() && (op_bytes == 4) ? 8 : op_bytes;
         dst.val = src.val;