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Subject[PATCH 39/54] KVM: x86 emulator: Fix stack instructions on 64-bit mode
Date
Stack instructions are always 64-bit on 64-bit mode; many of the
emulated stack instructions did not take that into account. Fix by
adding a 'Stack' bitflag and setting the operand size appropriately
during the decode stage (except for 'push r/m', which is in a group
with a few other instructions, so it gets its own treatment).

This fixes random crashes on Vista x64.

Signed-off-by: Avi Kivity <avi@qumranet.com>
---
drivers/kvm/x86_emulate.c | 27 +++++++++++++++------------
1 files changed, 15 insertions(+), 12 deletions(-)
diff --git a/drivers/kvm/x86_emulate.c b/drivers/kvm/x86_emulate.c
index f423b0e..0a6ab06 100644
--- a/drivers/kvm/x86_emulate.c
+++ b/drivers/kvm/x86_emulate.c
@@ -65,6 +65,7 @@
#define BitOp (1<<8)
#define MemAbs (1<<9) /* Memory operand is absolute displacement */
#define String (1<<10) /* String instruction (rep capable) */
+#define Stack (1<<11) /* Stack instruction (push/pop) */

static u16 opcode_table[256] = {
/* 0x00 - 0x07 */
@@ -104,14 +105,16 @@ static u16 opcode_table[256] = {
/* 0x48 - 0x4F */
DstReg, DstReg, DstReg, DstReg, DstReg, DstReg, DstReg, DstReg,
/* 0x50 - 0x57 */
- SrcReg, SrcReg, SrcReg, SrcReg, SrcReg, SrcReg, SrcReg, SrcReg,
+ SrcReg | Stack, SrcReg | Stack, SrcReg | Stack, SrcReg | Stack,
+ SrcReg | Stack, SrcReg | Stack, SrcReg | Stack, SrcReg | Stack,
/* 0x58 - 0x5F */
- DstReg, DstReg, DstReg, DstReg, DstReg, DstReg, DstReg, DstReg,
+ DstReg | Stack, DstReg | Stack, DstReg | Stack, DstReg | Stack,
+ DstReg | Stack, DstReg | Stack, DstReg | Stack, DstReg | Stack,
/* 0x60 - 0x67 */
0, 0, 0, DstReg | SrcMem32 | ModRM | Mov /* movsxd (x86/64) */ ,
0, 0, 0, 0,
/* 0x68 - 0x6F */
- 0, 0, ImplicitOps|Mov, 0,
+ 0, 0, ImplicitOps | Mov | Stack, 0,
SrcNone | ByteOp | ImplicitOps, SrcNone | ImplicitOps, /* insb, insw/insd */
SrcNone | ByteOp | ImplicitOps, SrcNone | ImplicitOps, /* outsb, outsw/outsd */
/* 0x70 - 0x77 */
@@ -128,9 +131,10 @@ static u16 opcode_table[256] = {
/* 0x88 - 0x8F */
ByteOp | DstMem | SrcReg | ModRM | Mov, DstMem | SrcReg | ModRM | Mov,
ByteOp | DstReg | SrcMem | ModRM | Mov, DstReg | SrcMem | ModRM | Mov,
- 0, ModRM | DstReg, 0, DstMem | SrcNone | ModRM | Mov,
+ 0, ModRM | DstReg, 0, DstMem | SrcNone | ModRM | Mov | Stack,
/* 0x90 - 0x9F */
- 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, ImplicitOps, ImplicitOps, 0, 0,
+ 0, 0, 0, 0, 0, 0, 0, 0,
+ 0, 0, 0, 0, ImplicitOps | Stack, ImplicitOps | Stack, 0, 0,
/* 0xA0 - 0xA7 */
ByteOp | DstReg | SrcMem | Mov | MemAbs, DstReg | SrcMem | Mov | MemAbs,
ByteOp | DstMem | SrcReg | Mov | MemAbs, DstMem | SrcReg | Mov | MemAbs,
@@ -144,7 +148,7 @@ static u16 opcode_table[256] = {
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
/* 0xC0 - 0xC7 */
ByteOp | DstMem | SrcImm | ModRM, DstMem | SrcImmByte | ModRM,
- 0, ImplicitOps, 0, 0,
+ 0, ImplicitOps | Stack, 0, 0,
ByteOp | DstMem | SrcImm | ModRM | Mov, DstMem | SrcImm | ModRM | Mov,
/* 0xC8 - 0xCF */
0, 0, 0, 0, 0, 0, 0, 0,
@@ -157,7 +161,8 @@ static u16 opcode_table[256] = {
/* 0xE0 - 0xE7 */
0, 0, 0, 0, 0, 0, 0, 0,
/* 0xE8 - 0xEF */
- ImplicitOps, SrcImm|ImplicitOps, 0, SrcImmByte|ImplicitOps, 0, 0, 0, 0,
+ ImplicitOps | Stack, SrcImm|ImplicitOps, 0, SrcImmByte|ImplicitOps,
+ 0, 0, 0, 0,
/* 0xF0 - 0xF7 */
0, 0, 0, 0,
ImplicitOps, ImplicitOps,
@@ -868,6 +873,9 @@ done_prefixes:
}
}

+ if (mode == X86EMUL_MODE_PROT64 && (c->d & Stack))
+ c->op_bytes = 8;
+
/* ModRM and SIB bytes. */
if (c->d & ModRM)
rc = decode_modrm(ctxt, ops);
@@ -988,11 +996,6 @@ static inline int emulate_grp1a(struct x86_emulate_ctxt *ctxt,
struct decode_cache *c = &ctxt->decode;
int rc;

- /* 64-bit mode: POP always pops a 64-bit operand. */
-
- if (ctxt->mode == X86EMUL_MODE_PROT64)
- c->dst.bytes = 8;
-
rc = ops->read_std(register_address(ctxt->ss_base,
c->regs[VCPU_REGS_RSP]),
&c->dst.val, c->dst.bytes, ctxt->vcpu);
--
1.5.3.7


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