x86_emulate: Emulate RETF and RETF imm16.

Signed-off-by: Keir Fraser <keir.fraser@citrix.com>

diff --git a/xen/arch/x86/x86_emulate.c b/xen/arch/x86/x86_emulate.c
index d6d849c14dd4fd4a0b83e01821b09521cee7935f..1397732a7f7f80209d054904be6f632ad968ec92 100644 (file)
--- a/xen/arch/x86/x86_emulate.c
+++ b/xen/arch/x86/x86_emulate.c
@@ -152,7 +152,8 @@ static uint8_t opcode_table[256] = {
     DstReg|SrcMem|ModRM|Mov, DstReg|SrcMem|ModRM|Mov,
     ByteOp|DstMem|SrcImm|ModRM|Mov, DstMem|SrcImm|ModRM|Mov,
     /* 0xC8 - 0xCF */
-    0, 0, 0, 0, ImplicitOps, ImplicitOps, ImplicitOps, ImplicitOps,
+    0, 0, ImplicitOps, ImplicitOps,
+    ImplicitOps, ImplicitOps, ImplicitOps, ImplicitOps,
     /* 0xD0 - 0xD7 */
     ByteOp|DstMem|SrcImplicit|ModRM, DstMem|SrcImplicit|ModRM, 
     ByteOp|DstMem|SrcImplicit|ModRM, DstMem|SrcImplicit|ModRM, 
@@ -2262,6 +2263,20 @@ x86_emulate(
         break;
     }
 
+    case 0xca: /* ret imm16 (far) */
+    case 0xcb: /* ret (far) */ {
+        int offset = (b == 0xca) ? insn_fetch_type(uint16_t) : 0;
+        op_bytes = mode_64bit() ? 8 : op_bytes;
+        if ( (rc = ops->read(x86_seg_ss, sp_post_inc(op_bytes),
+                             &dst.val, op_bytes, ctxt)) || 
+             (rc = ops->read(x86_seg_ss, sp_post_inc(op_bytes + offset),
+                             &src.val, op_bytes, ctxt)) ||
+             (rc = load_seg(x86_seg_cs, (uint16_t)src.val, ctxt, ops)) )
+            goto done;
+        _regs.eip = dst.val;
+        break;
+    }
+
     case 0xcc: /* int3 */
         src.val = EXC_BP;
         goto swint;