svn commit: r360176 - in head/sys/amd64: include vmm
Conrad Meyer
cem at FreeBSD.org
Tue Apr 21 21:33:07 UTC 2020
Author: cem
Date: Tue Apr 21 21:33:06 2020
New Revision: 360176
URL: https://svnweb.freebsd.org/changeset/base/360176
Log:
vmm(4): Decode 3-byte VEX-prefixed instructions
Reviewed by: grehan
Differential Revision: https://reviews.freebsd.org/D24462
Modified:
head/sys/amd64/include/vmm.h
head/sys/amd64/vmm/vmm_instruction_emul.c
Modified: head/sys/amd64/include/vmm.h
==============================================================================
--- head/sys/amd64/include/vmm.h Tue Apr 21 19:38:32 2020 (r360175)
+++ head/sys/amd64/include/vmm.h Tue Apr 21 21:33:06 2020 (r360176)
@@ -541,7 +541,8 @@ struct vie {
rm:4;
uint8_t ss:2, /* SIB byte */
- _sparebits:2,
+ vex_present:1, /* VEX prefixed */
+ vex_l:1, /* L bit */
index:4, /* SIB byte */
base:4; /* SIB byte */
@@ -550,7 +551,11 @@ struct vie {
uint8_t scale;
- uint8_t _sparebytes[3];
+ uint8_t vex_reg:4, /* vvvv: first source register specifier */
+ vex_pp:2, /* pp */
+ _sparebits:2;
+
+ uint8_t _sparebytes[2];
int base_register; /* VM_REG_GUEST_xyz */
int index_register; /* VM_REG_GUEST_xyz */
Modified: head/sys/amd64/vmm/vmm_instruction_emul.c
==============================================================================
--- head/sys/amd64/vmm/vmm_instruction_emul.c Tue Apr 21 19:38:32 2020 (r360175)
+++ head/sys/amd64/vmm/vmm_instruction_emul.c Tue Apr 21 21:33:06 2020 (r360176)
@@ -94,10 +94,13 @@ enum {
#define VIE_OP_F_NO_MODRM (1 << 3)
#define VIE_OP_F_NO_GLA_VERIFICATION (1 << 4)
+static const struct vie_op three_byte_opcodes_0f38[256] = {
+};
+
static const struct vie_op two_byte_opcodes[256] = {
[0xAE] = {
- .op_byte = 0xAE,
- .op_type = VIE_OP_TYPE_TWOB_GRP15,
+ .op_byte = 0xAE,
+ .op_type = VIE_OP_TYPE_TWOB_GRP15,
},
[0xB6] = {
.op_byte = 0xB6,
@@ -2286,6 +2289,81 @@ decode_prefixes(struct vie *vie, enum vm_cpu_mode cpu_
}
/*
+ * § 2.3.5, "The VEX Prefix", SDM Vol 2.
+ */
+ if ((cpu_mode == CPU_MODE_64BIT || cpu_mode == CPU_MODE_COMPATIBILITY)
+ && x == 0xC4) {
+ const struct vie_op *optab;
+
+ /* 3-byte VEX prefix. */
+ vie->vex_present = 1;
+
+ vie_advance(vie);
+ if (vie_peek(vie, &x))
+ return (-1);
+
+ /*
+ * 2nd byte: [R', X', B', mmmmm[4:0]]. Bits are inverted
+ * relative to REX encoding.
+ */
+ vie->rex_r = x & 0x80 ? 0 : 1;
+ vie->rex_x = x & 0x40 ? 0 : 1;
+ vie->rex_b = x & 0x20 ? 0 : 1;
+
+ switch (x & 0x1F) {
+ case 0x2:
+ /* 0F 38. */
+ optab = three_byte_opcodes_0f38;
+ break;
+ case 0x1:
+ /* 0F class - nothing handled here yet. */
+ /* FALLTHROUGH */
+ case 0x3:
+ /* 0F 3A class - nothing handled here yet. */
+ /* FALLTHROUGH */
+ default:
+ /* Reserved (#UD). */
+ return (-1);
+ }
+
+ vie_advance(vie);
+ if (vie_peek(vie, &x))
+ return (-1);
+
+ /* 3rd byte: [W, vvvv[6:3], L, pp[1:0]]. */
+ vie->rex_w = x & 0x80 ? 1 : 0;
+
+ vie->vex_reg = ((~(unsigned)x & 0x78u) >> 3);
+ vie->vex_l = !!(x & 0x4);
+ vie->vex_pp = (x & 0x3);
+
+ /* PP: 1=66 2=F3 3=F2 prefixes. */
+ switch (vie->vex_pp) {
+ case 0x1:
+ vie->opsize_override = 1;
+ break;
+ case 0x2:
+ vie->repz_present = 1;
+ break;
+ case 0x3:
+ vie->repnz_present = 1;
+ break;
+ }
+
+ vie_advance(vie);
+
+ /* Opcode, sans literal prefix prefix. */
+ if (vie_peek(vie, &x))
+ return (-1);
+
+ vie->op = optab[x];
+ if (vie->op.op_type == VIE_OP_TYPE_NONE)
+ return (-1);
+
+ vie_advance(vie);
+ }
+
+ /*
* Section "Operand-Size And Address-Size Attributes", Intel SDM, Vol 1
*/
if (cpu_mode == CPU_MODE_64BIT) {
@@ -2336,6 +2414,10 @@ decode_opcode(struct vie *vie)
if (vie_peek(vie, &x))
return (-1);
+
+ /* Already did this via VEX prefix. */
+ if (vie->op.op_type != VIE_OP_TYPE_NONE)
+ return (0);
vie->op = one_byte_opcodes[x];
More information about the svn-src-head
mailing list