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[Qemu-devel] [PATCH] target/i386: Fix handling of VEX prefixes
From: |
Peter Maydell |
Subject: |
[Qemu-devel] [PATCH] target/i386: Fix handling of VEX prefixes |
Date: |
Wed, 13 Dec 2017 11:19:19 +0000 |
In commit e3af7c788b73a6495eb9d94992ef11f6ad6f3c56 we
replaced direct calls to to cpu_ld*_code() with calls
to the x86_ld*_code() wrappers which incorporate an
advance of s->pc. Unfortunately we didn't notice that
in one place the old code was deliberately not incrementing
s->pc:
@@ -4501,7 +4528,7 @@ static target_ulong disas_insn(DisasContext *s, CPUState
*cpu)
static const int pp_prefix[4] = {
0, PREFIX_DATA, PREFIX_REPZ, PREFIX_REPNZ
};
- int vex3, vex2 = cpu_ldub_code(env, s->pc);
+ int vex3, vex2 = x86_ldub_code(env, s);
if (!CODE64(s) && (vex2 & 0xc0) != 0xc0) {
/* 4.1.4.6: In 32-bit mode, bits [7:6] must be 11b,
This meant we were mishandling this set of instructions.
Remove the manual advance of s->pc for the "is VEX" case
(which is now done by x86_ldub_code()) and instead rewind
PC in the case where we decide that this isn't really VEX.
Signed-off-by: Peter Maydell <address@hidden>
Cc: address@hidden
Reported-by: Alexandro Sanchez Bach <address@hidden>
---
I checked the rest of the changes in e3af7c788b73a and
I don't think we made this mistake anywhere else.
---
target/i386/translate.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/target/i386/translate.c b/target/i386/translate.c
index 088a9d9..ed5b69d 100644
--- a/target/i386/translate.c
+++ b/target/i386/translate.c
@@ -4547,9 +4547,9 @@ static target_ulong disas_insn(DisasContext *s, CPUState
*cpu)
if (!CODE64(s) && (vex2 & 0xc0) != 0xc0) {
/* 4.1.4.6: In 32-bit mode, bits [7:6] must be 11b,
otherwise the instruction is LES or LDS. */
+ s->pc--; /* rewind the advance_pc() x86_ldub_code() did */
break;
}
- s->pc++;
/* 4.1.1-4.1.3: No preceding lock, 66, f2, f3, or rex prefixes. */
if (prefixes & (PREFIX_REPZ | PREFIX_REPNZ
--
2.7.4
- [Qemu-devel] [PATCH] target/i386: Fix handling of VEX prefixes,
Peter Maydell <=