From: Nadav Amit <namit@xxxxxxxxxxxxxxxxx>
3.12-stable review patch. If anyone has any objections, please let me know.
===============
commit 58b7075d059f7d37ca86c76fb1446fa3447b9f4f upstream.
In 64-bit, stack operations default to 64-bits, but can be overriden (to
16-bit) using opsize override prefix. In contrast, near-branches are always
64-bit. This patch distinguish between the different behaviors.
Signed-off-by: Nadav Amit <namit@xxxxxxxxxxxxxxxxx>
Signed-off-by: Bruce Rogers <brogers@xxxxxxxx>
Signed-off-by: Jiri Slaby <jslaby@xxxxxxx>
---
arch/x86/kvm/emulate.c | 23 ++++++++++++++---------
1 file changed, 14 insertions(+), 9 deletions(-)
diff --git a/arch/x86/kvm/emulate.c b/arch/x86/kvm/emulate.c
index 4cb80f2c6fdb..987fdb379df6 100644
--- a/arch/x86/kvm/emulate.c
+++ b/arch/x86/kvm/emulate.c
@@ -161,6 +161,7 @@
#define Fastop ((u64)1 << 44) /* Use opcode::u.fastop */
#define NoWrite ((u64)1 << 45) /* No writeback */
#define SrcWrite ((u64)1 << 46) /* Write back src operand */
+#define NearBranch ((u64)1 << 52) /* Near branches */
#define DstXacc (DstAccLo | SrcAccHi | SrcWrite)
@@ -3646,9 +3647,9 @@ static const struct opcode group4[] = {
static const struct opcode group5[] = {
F(DstMem | SrcNone | Lock, em_inc),
F(DstMem | SrcNone | Lock, em_dec),
- I(SrcMem | Stack, em_call_near_abs),
+ I(SrcMem | NearBranch, em_call_near_abs),
I(SrcMemFAddr | ImplicitOps | Stack, em_call_far),
- I(SrcMem | Stack, em_jmp_abs),
+ I(SrcMem | NearBranch, em_jmp_abs),
I(SrcMemFAddr | ImplicitOps, em_jmp_far),
I(SrcMem | Stack, em_push), D(Undefined),
};
@@ -3812,7 +3813,7 @@ static const struct opcode opcode_table[256] = {
I2bvIP(DstDI | SrcDX | Mov | String | Unaligned, em_in, ins, check_perm_in), /* insb, insw/insd */
I2bvIP(SrcSI | DstDX | String, em_out, outs, check_perm_out), /* outsb, outsw/outsd */
/* 0x70 - 0x7F */
- X16(D(SrcImmByte)),
+ X16(D(SrcImmByte | NearBranch)),
/* 0x80 - 0x87 */
G(ByteOp | DstMem | SrcImm, group1),
G(DstMem | SrcImm, group1),
@@ -3850,8 +3851,8 @@ static const struct opcode opcode_table[256] = {
X8(I(DstReg | SrcImm64 | Mov, em_mov)),
/* 0xC0 - 0xC7 */
G(ByteOp | Src2ImmByte, group2), G(Src2ImmByte, group2),
- I(ImplicitOps | Stack | SrcImmU16, em_ret_near_imm),
- I(ImplicitOps | Stack, em_ret),
+ I(ImplicitOps | NearBranch | SrcImmU16, em_ret_near_imm),
+ I(ImplicitOps | NearBranch, em_ret),
I(DstReg | SrcMemFAddr | ModRM | No64 | Src2ES, em_lseg),
I(DstReg | SrcMemFAddr | ModRM | No64 | Src2DS, em_lseg),
G(ByteOp, group11), G(0, group11),
@@ -3872,11 +3873,11 @@ static const struct opcode opcode_table[256] = {
N, E(0, &escape_d9), N, E(0, &escape_db), N, E(0, &escape_dd), N, N,
/* 0xE0 - 0xE7 */
X3(I(SrcImmByte, em_loop)),
- I(SrcImmByte, em_jcxz),
+ I(SrcImmByte | NearBranch, em_jcxz),
I2bvIP(SrcImmUByte | DstAcc, em_in, in, check_perm_in),
I2bvIP(SrcAcc | DstImmUByte, em_out, out, check_perm_out),
/* 0xE8 - 0xEF */
- I(SrcImm | Stack, em_call), D(SrcImm | ImplicitOps),
+ I(SrcImm | NearBranch, em_call), D(SrcImm | ImplicitOps),
I(SrcImmFAddr | No64, em_jmp_far), D(SrcImmByte | ImplicitOps),
I2bvIP(SrcDX | DstAcc, em_in, in, check_perm_in),
I2bvIP(SrcAcc | DstDX, em_out, out, check_perm_out),
@@ -4356,8 +4357,12 @@ done_prefixes:
if (!(ctxt->d & VendorSpecific) && ctxt->only_vendor_specific_insn)
return EMULATION_FAILED;
- if (mode == X86EMUL_MODE_PROT64 && (ctxt->d & Stack))
- ctxt->op_bytes = 8;
+ if (mode == X86EMUL_MODE_PROT64) {
+ if (ctxt->op_bytes == 4 && (ctxt->d & Stack))
+ ctxt->op_bytes = 8;
+ else if (ctxt->d & NearBranch)
+ ctxt->op_bytes = 8;
+ }
if (ctxt->d & Op3264) {
if (mode == X86EMUL_MODE_PROT64)
--
2.2.2
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