linux/arch/x86/lib/inat.c
Masami Hiramatsu 130b78b2bf 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>
2011-12-05 14:53:15 +01:00

98 lines
2.7 KiB
C

/*
* x86 instruction attribute tables
*
* Written by Masami Hiramatsu <mhiramat@redhat.com>
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
*
*/
#include <asm/insn.h>
/* Attribute tables are generated from opcode map */
#include "inat-tables.c"
/* Attribute search APIs */
insn_attr_t inat_get_opcode_attribute(insn_byte_t opcode)
{
return inat_primary_table[opcode];
}
insn_attr_t inat_get_escape_attribute(insn_byte_t opcode, insn_byte_t last_pfx,
insn_attr_t esc_attr)
{
const insn_attr_t *table;
insn_attr_t lpfx_attr;
int n, m = 0;
n = inat_escape_id(esc_attr);
if (last_pfx) {
lpfx_attr = inat_get_opcode_attribute(last_pfx);
m = inat_last_prefix_id(lpfx_attr);
}
table = inat_escape_tables[n][0];
if (!table)
return 0;
if (inat_has_variant(table[opcode]) && m) {
table = inat_escape_tables[n][m];
if (!table)
return 0;
}
return table[opcode];
}
insn_attr_t inat_get_group_attribute(insn_byte_t modrm, insn_byte_t last_pfx,
insn_attr_t grp_attr)
{
const insn_attr_t *table;
insn_attr_t lpfx_attr;
int n, m = 0;
n = inat_group_id(grp_attr);
if (last_pfx) {
lpfx_attr = inat_get_opcode_attribute(last_pfx);
m = inat_last_prefix_id(lpfx_attr);
}
table = inat_group_tables[n][0];
if (!table)
return inat_group_common_attribute(grp_attr);
if (inat_has_variant(table[X86_MODRM_REG(modrm)]) && m) {
table = inat_group_tables[n][m];
if (!table)
return inat_group_common_attribute(grp_attr);
}
return table[X86_MODRM_REG(modrm)] |
inat_group_common_attribute(grp_attr);
}
insn_attr_t inat_get_avx_attribute(insn_byte_t opcode, insn_byte_t vex_m,
insn_byte_t vex_p)
{
const insn_attr_t *table;
if (vex_m > X86_VEX_M_MAX || vex_p > INAT_LSTPFX_MAX)
return 0;
/* 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];
}