target-i386: Fix addr16 prefix
While ADDSEG will only be false in 16-bit mode for LEA, it can be
false even in other cases when 16-bit addresses are obtained via
the 67h prefix in 32-bit mode. In this case, gen_lea_v_seg forgets
to add a nonzero FS or GS base if CS/DS/ES/SS are all zero. This
case is pretty rare but happens when booting Windows 95/98, and
this patch fixes it.
The bug is visible since commit d6a291498, but it was introduced
together with gen_lea_v_seg and it probably could be reproduced
with a "addr16 gs movsb" instruction as early as in commit
ca2f29f555805d07fb0b9ebfbbfc4e3656530977.
Reported-by: Hervé Poussineau <hpoussin@reactos.org>
Tested-by: Hervé Poussineau <hpoussin@reactos.org>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Message-Id: <1456931078-21635-1-git-send-email-pbonzini@redhat.com>
Signed-off-by: Richard Henderson <rth@twiddle.net>
diff --git a/target-i386/translate.c b/target-i386/translate.c
index b73c237..0b67165 100644
--- a/target-i386/translate.c
+++ b/target-i386/translate.c
@@ -466,15 +466,15 @@
break;
case MO_16:
/* 16 bit address */
- if (ovr_seg < 0) {
- ovr_seg = def_seg;
- }
tcg_gen_ext16u_tl(cpu_A0, a0);
- /* ADDSEG will only be false in 16-bit mode for LEA. */
- if (!s->addseg) {
- return;
- }
a0 = cpu_A0;
+ if (ovr_seg < 0) {
+ if (s->addseg) {
+ ovr_seg = def_seg;
+ } else {
+ return;
+ }
+ }
break;
default:
tcg_abort();