# HG changeset patch
# User Keir Fraser <keir.fraser@citrix.com>
# Date 1250694095 -3600
# Node ID 090e394202d0bb0089abc5e5276ed7fda283567d
# Parent  daf1ff2c7dbd59b2ab31e6427be58ffdc14e10fd
x86_emulate: Fixes for 'mov rm16,sreg'

1. Memory reads should be 16 bits only
2. Attempt to load %cs should result in #UD

Signed-off-by: Keir Fraser <keir.fraser@citrix.com>
xen-unstable changeset:   20035:3fe64f43944f
xen-unstable date:        Fri Aug 07 10:53:22 2009 +0100

Index: xen-3.4.1-testing/xen/arch/x86/x86_emulate/x86_emulate.c
===================================================================
--- xen-3.4.1-testing.orig/xen/arch/x86/x86_emulate/x86_emulate.c
+++ xen-3.4.1-testing/xen/arch/x86/x86_emulate/x86_emulate.c
@@ -113,7 +113,7 @@ static uint8_t opcode_table[256] = {
     ByteOp|DstMem|SrcReg|ModRM|Mov, DstMem|SrcReg|ModRM|Mov,
     ByteOp|DstReg|SrcMem|ModRM|Mov, DstReg|SrcMem|ModRM|Mov,
     DstMem|SrcReg|ModRM|Mov, DstReg|SrcNone|ModRM,
-    DstReg|SrcMem|ModRM|Mov, DstMem|SrcNone|ModRM|Mov,
+    DstReg|SrcMem16|ModRM|Mov, DstMem|SrcNone|ModRM|Mov,
     /* 0x90 - 0x97 */
     ImplicitOps, ImplicitOps, ImplicitOps, ImplicitOps,
     ImplicitOps, ImplicitOps, ImplicitOps, ImplicitOps,
@@ -2008,6 +2008,7 @@ x86_emulate(
     case 0x8e: /* mov r/m,Sreg */ {
         enum x86_segment seg = decode_segment(modrm_reg);
         generate_exception_if(seg == decode_segment_failed, EXC_UD, -1);
+        generate_exception_if(seg == x86_seg_cs, EXC_UD, -1);
         if ( (rc = load_seg(seg, (uint16_t)src.val, ctxt, ops)) != 0 )
             goto done;
         if ( seg == x86_seg_ss )