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authorMasami Hiramatsu <masami.hiramatsu.pt@hitachi.com>2011-12-05 16:05:39 +0400
committerIngo Molnar <mingo@elte.hu>2011-12-05 17:53:15 +0400
commit130b78b2bf16d5d89091db38374faef896360cf9 (patch)
tree46f1f553aba35de8e2ffea42128e2237da479dc6 /arch/x86/lib/inat.c
parent1056c3e916f12cdd8042ab27dfccbb3a9e871df0 (diff)
downloadlinux-130b78b2bf16d5d89091db38374faef896360cf9.tar.xz
x86: Fix instruction decoder to handle grouped AVX instructions
For reducing memory usage of attribute table, x86 instruction decoder puts "Group" attribute only on "no-last-prefix" attribute table (same as vex_p == 0 case). Thus, the decoder should look no-last-prefix table first, and then only if it is not a group, move on to "with-last-prefix" table (vex_p != 0). However, current implementation, inat_get_avx_attribute() looks with-last-prefix directly. So, when decoding a grouped AVX instruction, the decoder fails to find correct group because there is no "Group" attribute on the table. This ends up with the mis-decoding of instructions, as Ingo reported in http://thread.gmane.org/gmane.linux.kernel/1214103 This patch fixes it to check no-last-prefix table first even if that is an AVX instruction, and get an attribute from "with last-prefix" table only if that is not a group. Reported-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: yrl.pp-manager.tt@hitachi.com Link: http://lkml.kernel.org/r/20111205120539.15475.91428.stgit@cloud Signed-off-by: Ingo Molnar <mingo@elte.hu>
Diffstat (limited to 'arch/x86/lib/inat.c')
-rw-r--r--arch/x86/lib/inat.c9
1 files changed, 8 insertions, 1 deletions
diff --git a/arch/x86/lib/inat.c b/arch/x86/lib/inat.c
index 46fc4ee09fc4..88ad5fbda6e1 100644
--- a/arch/x86/lib/inat.c
+++ b/arch/x86/lib/inat.c
@@ -82,9 +82,16 @@ insn_attr_t inat_get_avx_attribute(insn_byte_t opcode, insn_byte_t vex_m,
const insn_attr_t *table;
if (vex_m > X86_VEX_M_MAX || vex_p > INAT_LSTPFX_MAX)
return 0;
- table = inat_avx_tables[vex_m][vex_p];
+ /* At first, this checks the master table */
+ table = inat_avx_tables[vex_m][0];
if (!table)
return 0;
+ if (!inat_is_group(table[opcode]) && vex_p) {
+ /* If this is not a group, get attribute directly */
+ table = inat_avx_tables[vex_m][vex_p];
+ if (!table)
+ return 0;
+ }
return table[opcode];
}