Commit-ID: a2a2d19f434380cd00fe31c9ea1734939eb2dadd
Gitweb: http://repo.or.cz/w/nasm.git?a=commitdiff;h=a2a2d19f434380cd00fe31c9ea1734939eb2dadd
Author: Cyrill Gorcunov <gor...@gm...>
AuthorDate: Thu, 5 Nov 2015 01:14:05 +0300
Committer: Cyrill Gorcunov <gor...@gm...>
CommitDate: Thu, 5 Nov 2015 01:14:45 +0300
disasm: Fix disassembling of evex prefix
As been pointed by @hpa evex is pretty fine in ia-32.
Quoting Peter
| This is wrong, though; EVEX is permitted in 32-bit mode just as VEX is.
| The key thing is that bits [7:5] have to be 1 in 32-bit mode. It is
| unclear what happens if these bits are 110 as that depends on if it is
| decoded using the modr/m decoder or not. For VEX prefixes we accept
| them as VEX in that case, which may not match the CPU.
This is a fix for commit db6ecf9b76a2
Reported-by: "H. Peter Anvin" <hp...@zy...>
Signed-off-by: Cyrill Gorcunov <gor...@gm...>
---
disasm.c | 6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)
diff --git a/disasm.c b/disasm.c
index da39632..51c6578 100644
--- a/disasm.c
+++ b/disasm.c
@@ -1215,9 +1215,9 @@ int32_t disasm(uint8_t *data, char *output, int outbufsize, int segsize,
case 0x62:
{
- uint8_t evex_p0 = data[1] & 0x0f;
- if (segsize == 64 &&
- ((evex_p0 >= 0x01) && (evex_p0 <= 0x03))) {
+ if (segsize == 64 || ((data[1] & 0xc0) == 0xc0)) {
+ uint8_t evex_p0 = data[1] & 0x0f;
+
data++; /* 62h EVEX prefix */
prefix.evex[0] = *data++;
prefix.evex[1] = *data++;
|
