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KVM: x86 emulator: address size and operand size overrides are sticky 

Current implementation is to toggle, which is incorrect.  Patch ported from
corresponding Xen code.

Signed-off-by: Avi Kivity <avi@qumranet.com>
This commit is contained in:
Avi Kivity 2007-11-22 14:16:12 +02:00
parent 90e0a28f6b
commit f21b8bf4cc
1 changed files with 12 additions and 7 deletions
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19
drivers/kvm/x86_emulate.c
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@ -758,6 +758,7 @@ x86_decode_insn(struct x86_emulate_ctxt *ctxt, struct x86_emulate_ops *ops)
struct decode_cache *c = &ctxt->decode;
int rc = 0;
int mode = ctxt->mode;
int def_op_bytes, def_ad_bytes;
/* Shadow copy of register state. Committed on successful emulation. */
@ -768,34 +769,38 @@ x86_decode_insn(struct x86_emulate_ctxt *ctxt, struct x86_emulate_ops *ops)
switch (mode) {
case X86EMUL_MODE_REAL:
case X86EMUL_MODE_PROT16:
c->op_bytes = c->ad_bytes = 2;
def_op_bytes = def_ad_bytes = 2;
break;
case X86EMUL_MODE_PROT32:
c->op_bytes = c->ad_bytes = 4;
def_op_bytes = def_ad_bytes = 4;
break;
#ifdef CONFIG_X86_64
case X86EMUL_MODE_PROT64:
c->op_bytes = 4;
c->ad_bytes = 8;
def_op_bytes = 4;
def_ad_bytes = 8;
break;
#endif
default:
return -1;
}
c->op_bytes = def_op_bytes;
c->ad_bytes = def_ad_bytes;
/* Legacy prefixes. */
for (;;) {
switch (c->b = insn_fetch(u8, 1, c->eip)) {
case 0x66: /* operand-size override */
c->op_bytes ^= 6; /* switch between 2/4 bytes */
/* switch between 2/4 bytes */
c->op_bytes = def_op_bytes ^ 6;
break;
case 0x67: /* address-size override */
if (mode == X86EMUL_MODE_PROT64)
/* switch between 4/8 bytes */
c->ad_bytes ^= 12;
c->ad_bytes = def_ad_bytes ^ 12;
else
/* switch between 2/4 bytes */
c->ad_bytes ^= 6;
c->ad_bytes = def_ad_bytes ^ 6;
break;
case 0x2e: /* CS override */
c->override_base = &ctxt->cs_base;