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authorAurelien Jarno <aurelien@aurel32.net>2010-03-06 18:02:31 +0100
committerAurelien Jarno <aurelien@aurel32.net>2010-03-10 08:52:46 +0100
commitd2df336c582d74650f4ccc3ef4e84ac86c2868fe (patch)
tree4f130f5d89984eea71bd177f9abb05db2dc9071c /target-i386
parentFix segfault with ram_size > 4095M without kvm (diff)
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target-i386: fix SIB decoding with index = 4
A SIB byte with an index of 4 means "no scaled index", even if the scale value is not 0. In 64-bit mode, if REX.X is used, an index of 4 selects %r12. This is correctly handled by the computation of the index variable, which includes the index bits, and also the REX.X prefix: index = ((code >> 3) & 7) | REX_X(s); Thanks to Avi Kivity, Jamie Lokier and Malc for the analysis of the problem and the initial patch. Signed-off-by: Aurelien Jarno <aurelien@aurel32.net> (cherry picked from commit b16f827bdf7444b8cd338b9ecb654b4752f47225)
Diffstat (limited to 'target-i386')
-rw-r--r--target-i386/translate.c4
1 files changed, 2 insertions, 2 deletions
diff --git a/target-i386/translate.c b/target-i386/translate.c
index 0f7255d9d..a61db16ec 100644
--- a/target-i386/translate.c
+++ b/target-i386/translate.c
@@ -2047,8 +2047,8 @@ static void gen_lea_modrm(DisasContext *s, int modrm, int *reg_ptr, int *offset_
gen_op_movl_A0_im(disp);
}
}
- /* XXX: index == 4 is always invalid */
- if (havesib && (index != 4 || scale != 0)) {
+ /* index == 4 means no index */
+ if (havesib && (index != 4)) {
#ifdef TARGET_X86_64
if (s->aflag == 2) {
gen_op_addq_A0_reg_sN(scale, index);