x86: Fix to decode grouped AVX with VEX pp bits

Fix to decode grouped AVX with VEX pp bits which should be
handled as same as last-prefixes. This fixes below warnings
in posttest with CONFIG_CRYPTO_SHA1_SSSE3=y.

 Warning: arch/x86/tools/test_get_len found difference at <sha1_transform_avx>:ffffffff810d5fc0
 Warning: ffffffff810d6069:	c5 f9 73 de 04       	vpsrldq $0x4,%xmm6,%xmm0
 Warning: objdump says 5 bytes, but insn_get_length() says 4
 ...

With this change, test_get_len can decode it correctly.

 $ arch/x86/tools/test_get_len -v -y
 ffffffff810d6069:       c5 f9 73 de 04          vpsrldq $0x4,%xmm6,%xmm0
 Succeed: decoded and checked 1 instructions

Reported-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Cc: yrl.pp-manager.tt@hitachi.com
Link: http://lkml.kernel.org/r/20120210053340.30429.73410.stgit@localhost.localdomain
Signed-off-by: Ingo Molnar <mingo@elte.hu>

1 files changed, 12 insertions, 6 deletions

diff --git a/arch/x86/include/asm/insn.h b/arch/x86/include/asm/insn.h
index 74df3f1eddfd..48eb30a86062 100644
--- a/arch/x86/include/asm/insn.h
+++ b/arch/x86/include/asm/insn.h
@@ -96,12 +96,6 @@ struct insn {
 #define X86_VEX_P(vex)  ((vex) & 0x03)          /* VEX3 Byte2, VEX2 Byte1 */
 #define X86_VEX_M_MAX   0x1f                    /* VEX3.M Maximum value */
 
-/* The last prefix is needed for two-byte and three-byte opcodes */
-static inline insn_byte_t insn_last_prefix(struct insn *insn)
-{
-        return insn->prefixes.bytes[3];
-}
-
 extern void insn_init(struct insn *insn, const void *kaddr, int x86_64);
 extern void insn_get_prefixes(struct insn *insn);
 extern void insn_get_opcode(struct insn *insn);
@@ -160,6 +154,18 @@ static inline insn_byte_t insn_vex_p_bits(struct insn *insn)
                 return X86_VEX_P(insn->vex_prefix.bytes[2]);
 }
 
+/* Get the last prefix id from last prefix or VEX prefix */
+static inline int insn_last_prefix_id(struct insn *insn)
+{
+        if (insn_is_avx(insn))
+                return insn_vex_p_bits(insn);   /* VEX_p is a SIMD prefix id */
+
+        if (insn->prefixes.bytes[3])
+                return inat_get_last_prefix_id(insn->prefixes.bytes[3]);
+
+        return 0;
+}
+
 /* Offset of each field from kaddr */
 static inline int insn_offset_rex_prefix(struct insn *insn)
 {