lkml.org 
[lkml]   [2012]   [Jun]   [4]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
From
Subject[BUGFIX PATCH] x86/insn: Fix to decode bsr/bsf/jmpe with operand-size prefix
Date
Fix x86 instruction decoder to decode bsr/bsf/jmpe with
operand-size prefix (66h). This fixes below failure of
the test case.

bsf/bsr/jmpe have a special encoding. Opcode map in
Intel Software Developers Manual vol2 says they have
TZCNT/LZCNT variants if it has F3h prefix. However, there
is no information if it has other 66h or F2h prefixes.
Current instruction decoder supposes that those are
a bad instruction, but it actually accept at least
operand-size prefix.

This fixes errors reported by test_get_len as below:

Warning: arch/x86/tools/test_get_len found difference at
<em_bsf>:ffffffff81036d87
Warning: ffffffff81036de5: 66 0f bc c2 bsf %dx,%ax
Warning: objdump says 4 bytes, but insn_get_length() says 3
Warning: arch/x86/tools/test_get_len found difference at
<em_bsr>:ffffffff81036ea6
Warning: ffffffff81036f04: 66 0f bd c2 bsr %dx,%ax
Warning: objdump says 4 bytes, but insn_get_length() says 3
Warning: decoded and checked 13298882 instructions with 2 warnings

Reported-by: Linus Torvalds <torvalds@linux-foundation.org>
Reported-by: Pekka Enberg <penberg@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Signed-off-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
---

arch/x86/lib/x86-opcode-map.txt | 8 ++++----
arch/x86/tools/gen-insn-attr-x86.awk | 14 +++++++++-----
2 files changed, 13 insertions(+), 9 deletions(-)

diff --git a/arch/x86/lib/x86-opcode-map.txt b/arch/x86/lib/x86-opcode-map.txt
index 8191379..5d7e51f 100644
--- a/arch/x86/lib/x86-opcode-map.txt
+++ b/arch/x86/lib/x86-opcode-map.txt
@@ -28,7 +28,7 @@
# - (66): the last prefix is 0x66
# - (F3): the last prefix is 0xF3
# - (F2): the last prefix is 0xF2
-#
+# - (!F3) : the last prefix is not 0xF3 (including non-last prefix case)

Table: one byte opcode
Referrer:
@@ -515,12 +515,12 @@ b4: LFS Gv,Mp
b5: LGS Gv,Mp
b6: MOVZX Gv,Eb
b7: MOVZX Gv,Ew
-b8: JMPE | POPCNT Gv,Ev (F3)
+b8: JMPE (!F3) | POPCNT Gv,Ev (F3)
b9: Grp10 (1A)
ba: Grp8 Ev,Ib (1A)
bb: BTC Ev,Gv
-bc: BSF Gv,Ev | TZCNT Gv,Ev (F3)
-bd: BSR Gv,Ev | LZCNT Gv,Ev (F3)
+bc: BSF Gv,Ev (!F3) | TZCNT Gv,Ev (F3)
+bd: BSR Gv,Ev (!F3) | LZCNT Gv,Ev (F3)
be: MOVSX Gv,Eb
bf: MOVSX Gv,Ew
# 0x0f 0xc0-0xcf
diff --git a/arch/x86/tools/gen-insn-attr-x86.awk b/arch/x86/tools/gen-insn-attr-x86.awk
index 5f6a5b6..ddcf39b 100644
--- a/arch/x86/tools/gen-insn-attr-x86.awk
+++ b/arch/x86/tools/gen-insn-attr-x86.awk
@@ -66,9 +66,10 @@ BEGIN {
rex_expr = "^REX(\\.[XRWB]+)*"
fpu_expr = "^ESC" # TODO

- lprefix1_expr = "\\(66\\)"
+ lprefix1_expr = "\\((66|!F3)\\)"
lprefix2_expr = "\\(F3\\)"
- lprefix3_expr = "\\(F2\\)"
+ lprefix3_expr = "\\((F2|!F3)\\)"
+ lprefix_expr = "\\((66|F2|F3)\\)"
max_lprefix = 4

# All opcodes starting with lower-case 'v' or with (v1) superscript
@@ -333,13 +334,16 @@ function convert_operands(count,opnd, i,j,imm,mod)
if (match(ext, lprefix1_expr)) {
lptable1[idx] = add_flags(lptable1[idx],flags)
variant = "INAT_VARIANT"
- } else if (match(ext, lprefix2_expr)) {
+ }
+ if (match(ext, lprefix2_expr)) {
lptable2[idx] = add_flags(lptable2[idx],flags)
variant = "INAT_VARIANT"
- } else if (match(ext, lprefix3_expr)) {
+ }
+ if (match(ext, lprefix3_expr)) {
lptable3[idx] = add_flags(lptable3[idx],flags)
variant = "INAT_VARIANT"
- } else {
+ }
+ if (!match(ext, lprefix_expr)){
table[idx] = add_flags(table[idx],flags)
}
}


\
 
 \ /
  Last update: 2012-06-04 19:41    [W:0.035 / U:0.252 seconds]
©2003-2018 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site