x86/insn: Add XOP prefix instructions decoder support

Support decoding AMD's XOP prefix encoded instructions.

These instructions are introduced for Bulldozer micro architecture, and not
supported on Intel's processors. But when compiling kernel with
CONFIG_X86_NATIVE_CPU on some AMD processor (e.g. -march=bdver2), these
instructions can be used.

Closes: https://lore.kernel.org/all/871pq06728.fsf@wylie.me.uk/
Reported-by: Alan J. Wylie <alan@wylie.me.uk>
Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Tested-by: Alan J. Wylie <alan@wylie.me.uk>
Link: https://lore.kernel.org/175386161199.564247.597496379413236944.stgit@devnote2

2 files changed, 63 insertions, 3 deletions

diff --git a/tools/arch/x86/include/asm/inat.h b/tools/arch/x86/include/asm/inat.h
index 183aa662b165..099e926595bd 100644
--- a/tools/arch/x86/include/asm/inat.h
+++ b/tools/arch/x86/include/asm/inat.h
@@ -37,6 +37,8 @@
 #define INAT_PFX_EVEX	15	/* EVEX prefix */
 /* x86-64 REX2 prefix */
 #define INAT_PFX_REX2	16	/* 0xD5 */
+/* AMD XOP prefix */
+#define INAT_PFX_XOP	17	/* 0x8F */
 
 #define INAT_LSTPFX_MAX	3
 #define INAT_LGCPFX_MAX	11
@@ -77,6 +79,7 @@
 #define INAT_MOFFSET	(1 << (INAT_FLAG_OFFS + 3))
 #define INAT_VARIANT	(1 << (INAT_FLAG_OFFS + 4))
 #define INAT_VEXOK	(1 << (INAT_FLAG_OFFS + 5))
+#define INAT_XOPOK	INAT_VEXOK
 #define INAT_VEXONLY	(1 << (INAT_FLAG_OFFS + 6))
 #define INAT_EVEXONLY	(1 << (INAT_FLAG_OFFS + 7))
 #define INAT_NO_REX2	(1 << (INAT_FLAG_OFFS + 8))
@@ -111,6 +114,8 @@ extern insn_attr_t inat_get_group_attribute(insn_byte_t modrm,
 extern insn_attr_t inat_get_avx_attribute(insn_byte_t opcode,
 					  insn_byte_t vex_m,
 					  insn_byte_t vex_pp);
+extern insn_attr_t inat_get_xop_attribute(insn_byte_t opcode,
+					  insn_byte_t map_select);
 
 /* Attribute checking functions */
 static inline int inat_is_legacy_prefix(insn_attr_t attr)
@@ -164,6 +169,11 @@ static inline int inat_is_vex3_prefix(insn_attr_t attr)
 	return (attr & INAT_PFX_MASK) == INAT_PFX_VEX3;
 }
 
+static inline int inat_is_xop_prefix(insn_attr_t attr)
+{
+	return (attr & INAT_PFX_MASK) == INAT_PFX_XOP;
+}
+
 static inline int inat_is_escape(insn_attr_t attr)
 {
 	return attr & INAT_ESC_MASK;
@@ -229,6 +239,11 @@ static inline int inat_accept_vex(insn_attr_t attr)
 	return attr & INAT_VEXOK;
 }
 
+static inline int inat_accept_xop(insn_attr_t attr)
+{
+	return attr & INAT_XOPOK;
+}
+
 static inline int inat_must_vex(insn_attr_t attr)
 {
 	return attr & (INAT_VEXONLY | INAT_EVEXONLY);
diff --git a/tools/arch/x86/include/asm/insn.h b/tools/arch/x86/include/asm/insn.h
index 0e5abd896ad4..c683d609934b 100644
--- a/tools/arch/x86/include/asm/insn.h
+++ b/tools/arch/x86/include/asm/insn.h
@@ -71,7 +71,10 @@ struct insn {
 					 * prefixes.bytes[3]: last prefix
 					 */
 	struct insn_field rex_prefix;	/* REX prefix */
-	struct insn_field vex_prefix;	/* VEX prefix */
+	union {
+		struct insn_field vex_prefix;	/* VEX prefix */
+		struct insn_field xop_prefix;	/* XOP prefix */
+	};
 	struct insn_field opcode;	/*
 					 * opcode.bytes[0]: opcode1
 					 * opcode.bytes[1]: opcode2
@@ -135,6 +138,17 @@ struct insn {
 #define X86_VEX_V(vex)	(((vex) & 0x78) >> 3)	/* VEX3 Byte2, VEX2 Byte1 */
 #define X86_VEX_P(vex)	((vex) & 0x03)		/* VEX3 Byte2, VEX2 Byte1 */
 #define X86_VEX_M_MAX	0x1f			/* VEX3.M Maximum value */
+/* XOP bit fields */
+#define X86_XOP_R(xop)	((xop) & 0x80)	/* XOP Byte2 */
+#define X86_XOP_X(xop)	((xop) & 0x40)	/* XOP Byte2 */
+#define X86_XOP_B(xop)	((xop) & 0x20)	/* XOP Byte2 */
+#define X86_XOP_M(xop)	((xop) & 0x1f)	/* XOP Byte2 */
+#define X86_XOP_W(xop)	((xop) & 0x80)	/* XOP Byte3 */
+#define X86_XOP_V(xop)	((xop) & 0x78)	/* XOP Byte3 */
+#define X86_XOP_L(xop)	((xop) & 0x04)	/* XOP Byte3 */
+#define X86_XOP_P(xop)	((xop) & 0x03)	/* XOP Byte3 */
+#define X86_XOP_M_MIN	0x08	/* Min of XOP.M */
+#define X86_XOP_M_MAX	0x1f	/* Max of XOP.M */
 
 extern void insn_init(struct insn *insn, const void *kaddr, int buf_len, int x86_64);
 extern int insn_get_prefixes(struct insn *insn);
@@ -178,7 +192,7 @@ static inline insn_byte_t insn_rex2_m_bit(struct insn *insn)
 	return X86_REX2_M(insn->rex_prefix.bytes[1]);
 }
 
-static inline int insn_is_avx(struct insn *insn)
+static inline int insn_is_avx_or_xop(struct insn *insn)
 {
 	if (!insn->prefixes.got)
 		insn_get_prefixes(insn);
@@ -192,6 +206,22 @@ static inline int insn_is_evex(struct insn *insn)
 	return (insn->vex_prefix.nbytes == 4);
 }
 
+/* If we already know this is AVX/XOP encoded */
+static inline int avx_insn_is_xop(struct insn *insn)
+{
+	insn_attr_t attr = inat_get_opcode_attribute(insn->vex_prefix.bytes[0]);
+
+	return inat_is_xop_prefix(attr);
+}
+
+static inline int insn_is_xop(struct insn *insn)
+{
+	if (!insn_is_avx_or_xop(insn))
+		return 0;
+
+	return avx_insn_is_xop(insn);
+}
+
 static inline int insn_has_emulate_prefix(struct insn *insn)
 {
 	return !!insn->emulate_prefix_size;
@@ -222,11 +252,26 @@ static inline insn_byte_t insn_vex_w_bit(struct insn *insn)
 	return X86_VEX_W(insn->vex_prefix.bytes[2]);
 }
 
+static inline insn_byte_t insn_xop_map_bits(struct insn *insn)
+{
+	if (insn->xop_prefix.nbytes < 3)	/* XOP is 3 bytes */
+		return 0;
+	return X86_XOP_M(insn->xop_prefix.bytes[1]);
+}
+
+static inline insn_byte_t insn_xop_p_bits(struct insn *insn)
+{
+	return X86_XOP_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))
+	if (insn_is_avx_or_xop(insn)) {
+		if (avx_insn_is_xop(insn))
+			return insn_xop_p_bits(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]);