[Xen-changelog] [xen-unstable] [XEN] Fix SIB byte decode when extended by REX.X and REX.B.

[Xen patchbot-unstable <patchbot-unstable@xxxxxxxxxxxxxxxxxxx>]

# HG changeset patch
# User kfraser@xxxxxxxxxxxxxxxxxxxxx
# Node ID b1d538e557eebfdc72680c3d9087ecea396d0abe
# Parent  5d6be0099bdfebb260480176a2e051d83b18d3ed
[XEN] Fix SIB byte decode when extended by REX.X and REX.B.
Signed-off-by: Keir Fraser <keir@xxxxxxxxxxxxx>
---
 xen/arch/x86/x86_emulate.c |    4 ++--
 1 files changed, 2 insertions(+), 2 deletions(-)

diff -r 5d6be0099bdf -r b1d538e557ee xen/arch/x86/x86_emulate.c
--- a/xen/arch/x86/x86_emulate.c        Thu Nov 30 13:05:27 2006 +0000
+++ b/xen/arch/x86/x86_emulate.c        Thu Nov 30 14:04:36 2006 +0000
@@ -611,8 +611,8 @@ x86_emulate_memop(
             if ( modrm_rm == 4 )
             {
                 sib = insn_fetch(uint8_t);
-                sib_index = ((sib >> 3) & 7) | ((modrm << 2) & 8);
-                sib_base  = (sib & 7) | ((modrm << 3) & 8);
+                sib_index = ((sib >> 3) & 7) | ((rex_prefix << 2) & 8);
+                sib_base  = (sib & 7) | ((rex_prefix << 3) & 8);
                 if ( sib_index != 4 )
                     ea_off = *(long *)decode_register(sib_index, &_regs, 0);
                 ea_off <<= (sib >> 6) & 3;

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