Author: neel
Date: Wed Jan 30 04:09:09 2013
New Revision: 246108
URL: http://svnweb.freebsd.org/changeset/base/246108
Log:
Add emulation support for instruction "88/r: mov r/m8, r8".
This instruction moves a byte from a register to a memory location.
Tested by: tycho nightingale at pluribusnetworks com
Modified:
head/sys/amd64/include/vmm_instruction_emul.h
head/sys/amd64/vmm/vmm_instruction_emul.c
Modified: head/sys/amd64/include/vmm_instruction_emul.h
==============================================================================
--- head/sys/amd64/include/vmm_instruction_emul.h Wed Jan 30 01:43:00
2013 (r246107)
+++ head/sys/amd64/include/vmm_instruction_emul.h Wed Jan 30 04:09:09
2013 (r246108)
@@ -49,7 +49,8 @@ struct vie {
uint8_t rex_w:1, /* REX prefix */
rex_r:1,
rex_x:1,
- rex_b:1;
+ rex_b:1,
+ rex_present:1;
uint8_t mod:2, /* ModRM byte */
reg:4,
Modified: head/sys/amd64/vmm/vmm_instruction_emul.c
==============================================================================
--- head/sys/amd64/vmm/vmm_instruction_emul.c Wed Jan 30 01:43:00 2013
(r246107)
+++ head/sys/amd64/vmm/vmm_instruction_emul.c Wed Jan 30 04:09:09 2013
(r246108)
@@ -65,6 +65,10 @@ enum {
#define VIE_OP_F_IMM8 (1 << 1) /* 8-bit immediate
operand */
static const struct vie_op one_byte_opcodes[256] = {
+ [0x88] = {
+ .op_byte = 0x88,
+ .op_type = VIE_OP_TYPE_MOV,
+ },
[0x89] = {
.op_byte = 0x89,
.op_type = VIE_OP_TYPE_MOV,
@@ -161,6 +165,46 @@ vie_read_register(void *vm, int vcpuid,
}
static int
+vie_read_bytereg(void *vm, int vcpuid, struct vie *vie, uint8_t *rval)
+{
+ uint64_t val;
+ int error, rshift;
+ enum vm_reg_name reg;
+
+ rshift = 0;
+ reg = gpr_map[vie->reg];
+
+ /*
+ * 64-bit mode imposes limitations on accessing legacy byte registers.
+ *
+ * The legacy high-byte registers cannot be addressed if the REX
+ * prefix is present. In this case the values 4, 5, 6 and 7 of the
+ * 'ModRM:reg' field address %spl, %bpl, %sil and %dil respectively.
+ *
+ * If the REX prefix is not present then the values 4, 5, 6 and 7
+ * of the 'ModRM:reg' field address the legacy high-byte registers,
+ * %ah, %ch, %dh and %bh respectively.
+ */
+ if (!vie->rex_present) {
+ if (vie->reg & 0x4) {
+ /*
+ * Obtain the value of %ah by reading %rax and shifting
+ * right by 8 bits (same for %bh, %ch and %dh).
+ */
+ rshift = 8;
+ reg = gpr_map[vie->reg & 0x3];
+ }
+ }
+
+ if (!vie_valid_register(reg))
+ return (EINVAL);
+
+ error = vm_get_register(vm, vcpuid, reg, &val);
+ *rval = val >> rshift;
+ return (error);
+}
+
+static int
vie_update_register(void *vm, int vcpuid, enum vm_reg_name reg,
uint64_t val, int size)
{
@@ -209,12 +253,24 @@ emulate_mov(void *vm, int vcpuid, uint64
{
int error, size;
enum vm_reg_name reg;
+ uint8_t byte;
uint64_t val;
size = 4;
error = EINVAL;
switch (vie->op.op_byte) {
+ case 0x88:
+ /*
+ * MOV byte from reg (ModRM:reg) to mem (ModRM:r/m)
+ * 88/r: mov r/m8, r8
+ * REX + 88/r: mov r/m8, r8 (%ah, %ch, %dh, %bh not available)
+ */
+ size = 1;
+ error = vie_read_bytereg(vm, vcpuid, vie, &byte);
+ if (error == 0)
+ error = memwrite(vm, vcpuid, gpa, byte, size, arg);
+ break;
case 0x89:
/*
* MOV from reg (ModRM:reg) to mem (ModRM:r/m)
@@ -497,6 +553,8 @@ decode_rex(struct vie *vie)
return (-1);
if (x >= 0x40 && x <= 0x4F) {
+ vie->rex_present = 1;
+
vie->rex_w = x & 0x8 ? 1 : 0;
vie->rex_r = x & 0x4 ? 1 : 0;
vie->rex_x = x & 0x2 ? 1 : 0;
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