# HG changeset patch
# User Keir Fraser <keir.fraser@xxxxxxxxxx>
# Date 1196014053 0
# Node ID 6d129d0933942ca2ff672c1f23cf26379c1db129
# Parent 7c6944d861b21772faa1898a00322a382166ca6e
x86_emulate: Emulate CMPS and SCAS string-compare instructions.
Signed-off-by: Keir Fraser <keir.fraser@xxxxxxxxxx>
---
xen/arch/x86/x86_emulate.c | 51 ++++++++++++++++++++++++++++++++++++++++++---
1 files changed, 48 insertions(+), 3 deletions(-)
diff -r 7c6944d861b2 -r 6d129d093394 xen/arch/x86/x86_emulate.c
--- a/xen/arch/x86/x86_emulate.c Sun Nov 25 18:06:30 2007 +0000
+++ b/xen/arch/x86/x86_emulate.c Sun Nov 25 18:07:33 2007 +0000
@@ -131,11 +131,13 @@ static uint8_t opcode_table[256] = {
/* 0xA0 - 0xA7 */
ByteOp|ImplicitOps|Mov, ImplicitOps|Mov,
ByteOp|ImplicitOps|Mov, ImplicitOps|Mov,
- ByteOp|ImplicitOps|Mov, ImplicitOps|Mov, 0, 0,
+ ByteOp|ImplicitOps|Mov, ImplicitOps|Mov,
+ ByteOp|ImplicitOps, ImplicitOps,
/* 0xA8 - 0xAF */
ByteOp|DstReg|SrcImm, DstReg|SrcImm,
ByteOp|ImplicitOps|Mov, ImplicitOps|Mov,
- ByteOp|ImplicitOps|Mov, ImplicitOps|Mov, 0, 0,
+ ByteOp|ImplicitOps|Mov, ImplicitOps|Mov,
+ ByteOp|ImplicitOps, ImplicitOps,
/* 0xB0 - 0xB7 */
ByteOp|DstReg|SrcImm|Mov, ByteOp|DstReg|SrcImm|Mov,
ByteOp|DstReg|SrcImm|Mov, ByteOp|DstReg|SrcImm|Mov,
@@ -828,6 +830,8 @@ x86_emulate(
uint8_t b, d, sib, sib_index, sib_base, twobyte = 0, rex_prefix = 0;
uint8_t modrm, modrm_mod = 0, modrm_reg = 0, modrm_rm = 0;
unsigned int op_bytes, def_op_bytes, ad_bytes, def_ad_bytes;
+#define REPE_PREFIX 1
+#define REPNE_PREFIX 2
unsigned int lock_prefix = 0, rep_prefix = 0;
int override_seg = -1, rc = X86EMUL_OKAY;
struct operand src, dst;
@@ -882,8 +886,10 @@ x86_emulate(
lock_prefix = 1;
break;
case 0xf2: /* REPNE/REPNZ */
+ rep_prefix = REPNE_PREFIX;
+ break;
case 0xf3: /* REP/REPE/REPZ */
- rep_prefix = 1;
+ rep_prefix = REPE_PREFIX;
break;
case 0x40 ... 0x4f: /* REX */
if ( !mode_64bit() )
@@ -2161,6 +2167,27 @@ x86_emulate(
_regs.edi, (_regs.eflags & EFLG_DF) ? -dst.bytes : dst.bytes);
break;
+ case 0xa6 ... 0xa7: /* cmps */ {
+ unsigned long next_eip = _regs.eip;
+ handle_rep_prefix();
+ src.bytes = dst.bytes = (d & ByteOp) ? 1 : op_bytes;
+ if ( (rc = ops->read(ea.mem.seg, truncate_ea(_regs.esi),
+ &dst.val, dst.bytes, ctxt)) ||
+ (rc = ops->read(x86_seg_es, truncate_ea(_regs.edi),
+ &src.val, src.bytes, ctxt)) )
+ goto done;
+ register_address_increment(
+ _regs.esi, (_regs.eflags & EFLG_DF) ? -dst.bytes : dst.bytes);
+ register_address_increment(
+ _regs.edi, (_regs.eflags & EFLG_DF) ? -src.bytes : src.bytes);
+ /* cmp: dst - src ==> src=*%%edi,dst=*%%esi ==> *%%esi - *%%edi */
+ emulate_2op_SrcV("cmp", src, dst, _regs.eflags);
+ if ( ((rep_prefix == REPE_PREFIX) && !(_regs.eflags & EFLG_ZF)) ||
+ ((rep_prefix == REPNE_PREFIX) && (_regs.eflags & EFLG_ZF)) )
+ _regs.eip = next_eip;
+ break;
+ }
+
case 0xaa ... 0xab: /* stos */
handle_rep_prefix();
dst.type = OP_MEM;
@@ -2183,6 +2210,24 @@ x86_emulate(
register_address_increment(
_regs.esi, (_regs.eflags & EFLG_DF) ? -dst.bytes : dst.bytes);
break;
+
+ case 0xae ... 0xaf: /* scas */ {
+ unsigned long next_eip = _regs.eip;
+ handle_rep_prefix();
+ src.bytes = dst.bytes = (d & ByteOp) ? 1 : op_bytes;
+ dst.val = _regs.eax;
+ if ( (rc = ops->read(x86_seg_es, truncate_ea(_regs.edi),
+ &src.val, src.bytes, ctxt)) != 0 )
+ goto done;
+ register_address_increment(
+ _regs.edi, (_regs.eflags & EFLG_DF) ? -src.bytes : src.bytes);
+ /* cmp: dst - src ==> src=*%%edi,dst=%%eax ==> %%eax - *%%edi */
+ emulate_2op_SrcV("cmp", src, dst, _regs.eflags);
+ if ( ((rep_prefix == REPE_PREFIX) && !(_regs.eflags & EFLG_ZF)) ||
+ ((rep_prefix == REPNE_PREFIX) && (_regs.eflags & EFLG_ZF)) )
+ _regs.eip = next_eip;
+ break;
+ }
case 0xc2: /* ret imm16 (near) */
case 0xc3: /* ret (near) */ {
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