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| author | Aurelien Jarno <aurelien@aurel32.net> | 2010-03-06 18:02:31 +0100 |
|---|---|---|
| committer | Aurelien Jarno <aurelien@aurel32.net> | 2010-03-10 08:43:43 +0100 |
| commit | b16f827bdf7444b8cd338b9ecb654b4752f47225 (patch) | |
| tree | 03ed0f417f2ba6db17a230b5e19430ada973e328 /target-i386/translate.c | |
| parent | 1298cb6804d6073ef3cb9c06e663ee59d06d92cc (diff) | |
| download | qemu-b16f827bdf7444b8cd338b9ecb654b4752f47225.tar.gz | |
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>
Diffstat (limited to 'target-i386/translate.c')
| -rw-r--r-- | target-i386/translate.c | 4 |
1 files changed, 2 insertions, 2 deletions
diff --git a/target-i386/translate.c b/target-i386/translate.c index 7a99e2055a..9dafc880bf 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); |