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| author | Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com> | 2011-12-05 21:05:39 +0900 |
|---|---|---|
| committer | Ingo Molnar <mingo@elte.hu> | 2011-12-05 14:53:15 +0100 |
| commit | 130b78b2bf16d5d89091db38374faef896360cf9 (patch) | |
| tree | 46f1f553aba35de8e2ffea42128e2237da479dc6 | |
| parent | 1056c3e916f12cdd8042ab27dfccbb3a9e871df0 (diff) | |
| download | linux-130b78b2bf16d5d89091db38374faef896360cf9.tar.bz2 | |
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>
| -rw-r--r-- | arch/x86/lib/inat.c | 9 | ||||
| -rw-r--r-- | arch/x86/lib/insn.c | 4 |
2 files changed, 11 insertions, 2 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]; } diff --git a/arch/x86/lib/insn.c b/arch/x86/lib/insn.c index 374562ed6704..5a1f9f3e3fbb 100644 --- a/arch/x86/lib/insn.c +++ b/arch/x86/lib/insn.c @@ -202,7 +202,7 @@ void insn_get_opcode(struct insn *insn) m = insn_vex_m_bits(insn); p = insn_vex_p_bits(insn); insn->attr = inat_get_avx_attribute(op, m, p); - if (!inat_accept_vex(insn->attr)) + if (!inat_accept_vex(insn->attr) && !inat_is_group(insn->attr)) insn->attr = 0; /* This instruction is bad */ goto end; /* VEX has only 1 byte for opcode */ } @@ -249,6 +249,8 @@ void insn_get_modrm(struct insn *insn) pfx = insn_last_prefix(insn); insn->attr = inat_get_group_attribute(mod, pfx, insn->attr); + if (insn_is_avx(insn) && !inat_accept_vex(insn->attr)) + insn->attr = 0; /* This is bad */ } } |