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Subject[PATCH 05/42] KVM: x86 emulator: Add 'push/pop sreg' instructions
Date
From: Mohammed Gamal <m.gamal005@gmail.com>

[avi: avoid buffer overflow]

Signed-off-by: Mohammed Gamal <m.gamal005@gmail.com>
Signed-off-by: Avi Kivity <avi@redhat.com>
---
arch/x86/kvm/emulate.c | 107 +++++++++++++++++++++++++++++++++++++++++++++---
1 files changed, 101 insertions(+), 6 deletions(-)
diff --git a/arch/x86/kvm/emulate.c b/arch/x86/kvm/emulate.c
index 1be5cd6..1cdfec5 100644
--- a/arch/x86/kvm/emulate.c
+++ b/arch/x86/kvm/emulate.c
@@ -92,19 +92,22 @@ static u32 opcode_table[256] = {
/* 0x00 - 0x07 */
ByteOp | DstMem | SrcReg | ModRM, DstMem | SrcReg | ModRM,
ByteOp | DstReg | SrcMem | ModRM, DstReg | SrcMem | ModRM,
- ByteOp | DstAcc | SrcImm, DstAcc | SrcImm, 0, 0,
+ ByteOp | DstAcc | SrcImm, DstAcc | SrcImm,
+ ImplicitOps | Stack, ImplicitOps | Stack,
/* 0x08 - 0x0F */
ByteOp | DstMem | SrcReg | ModRM, DstMem | SrcReg | ModRM,
ByteOp | DstReg | SrcMem | ModRM, DstReg | SrcMem | ModRM,
- 0, 0, 0, 0,
+ 0, 0, ImplicitOps | Stack, 0,
/* 0x10 - 0x17 */
ByteOp | DstMem | SrcReg | ModRM, DstMem | SrcReg | ModRM,
ByteOp | DstReg | SrcMem | ModRM, DstReg | SrcMem | ModRM,
- ByteOp | DstAcc | SrcImm, DstAcc | SrcImm, 0, 0,
+ ByteOp | DstAcc | SrcImm, DstAcc | SrcImm,
+ ImplicitOps | Stack, ImplicitOps | Stack,
/* 0x18 - 0x1F */
ByteOp | DstMem | SrcReg | ModRM, DstMem | SrcReg | ModRM,
ByteOp | DstReg | SrcMem | ModRM, DstReg | SrcMem | ModRM,
- ByteOp | DstAcc | SrcImm, DstAcc | SrcImm, 0, 0,
+ ByteOp | DstAcc | SrcImm, DstAcc | SrcImm,
+ ImplicitOps | Stack, ImplicitOps | Stack,
/* 0x20 - 0x27 */
ByteOp | DstMem | SrcReg | ModRM, DstMem | SrcReg | ModRM,
ByteOp | DstReg | SrcMem | ModRM, DstReg | SrcMem | ModRM,
@@ -244,11 +247,13 @@ static u32 twobyte_table[256] = {
/* 0x90 - 0x9F */
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
/* 0xA0 - 0xA7 */
- 0, 0, 0, DstMem | SrcReg | ModRM | BitOp,
+ ImplicitOps | Stack, ImplicitOps | Stack,
+ 0, DstMem | SrcReg | ModRM | BitOp,
DstMem | SrcReg | Src2ImmByte | ModRM,
DstMem | SrcReg | Src2CL | ModRM, 0, 0,
/* 0xA8 - 0xAF */
- 0, 0, 0, DstMem | SrcReg | ModRM | BitOp,
+ ImplicitOps | Stack, ImplicitOps | Stack,
+ 0, DstMem | SrcReg | ModRM | BitOp,
DstMem | SrcReg | Src2ImmByte | ModRM,
DstMem | SrcReg | Src2CL | ModRM,
ModRM, 0,
@@ -1186,6 +1191,32 @@ static int emulate_pop(struct x86_emulate_ctxt *ctxt,
return rc;
}

+static void emulate_push_sreg(struct x86_emulate_ctxt *ctxt, int seg)
+{
+ struct decode_cache *c = &ctxt->decode;
+ struct kvm_segment segment;
+
+ kvm_x86_ops->get_segment(ctxt->vcpu, &segment, seg);
+
+ c->src.val = segment.selector;
+ emulate_push(ctxt);
+}
+
+static int emulate_pop_sreg(struct x86_emulate_ctxt *ctxt,
+ struct x86_emulate_ops *ops, int seg)
+{
+ struct decode_cache *c = &ctxt->decode;
+ unsigned long selector;
+ int rc;
+
+ rc = emulate_pop(ctxt, ops, &selector, c->op_bytes);
+ if (rc != 0)
+ return rc;
+
+ rc = kvm_load_segment_descriptor(ctxt->vcpu, (u16)selector, 1, seg);
+ return rc;
+}
+
static inline int emulate_grp1a(struct x86_emulate_ctxt *ctxt,
struct x86_emulate_ops *ops)
{
@@ -1707,18 +1738,66 @@ special_insn:
add: /* add */
emulate_2op_SrcV("add", c->src, c->dst, ctxt->eflags);
break;
+ case 0x06: /* push es */
+ if (ctxt->mode == X86EMUL_MODE_PROT64)
+ goto cannot_emulate;
+
+ emulate_push_sreg(ctxt, VCPU_SREG_ES);
+ break;
+ case 0x07: /* pop es */
+ if (ctxt->mode == X86EMUL_MODE_PROT64)
+ goto cannot_emulate;
+
+ rc = emulate_pop_sreg(ctxt, ops, VCPU_SREG_ES);
+ if (rc != 0)
+ goto done;
+ break;
case 0x08 ... 0x0d:
or: /* or */
emulate_2op_SrcV("or", c->src, c->dst, ctxt->eflags);
break;
+ case 0x0e: /* push cs */
+ if (ctxt->mode == X86EMUL_MODE_PROT64)
+ goto cannot_emulate;
+
+ emulate_push_sreg(ctxt, VCPU_SREG_CS);
+ break;
case 0x10 ... 0x15:
adc: /* adc */
emulate_2op_SrcV("adc", c->src, c->dst, ctxt->eflags);
break;
+ case 0x16: /* push ss */
+ if (ctxt->mode == X86EMUL_MODE_PROT64)
+ goto cannot_emulate;
+
+ emulate_push_sreg(ctxt, VCPU_SREG_SS);
+ break;
+ case 0x17: /* pop ss */
+ if (ctxt->mode == X86EMUL_MODE_PROT64)
+ goto cannot_emulate;
+
+ rc = emulate_pop_sreg(ctxt, ops, VCPU_SREG_SS);
+ if (rc != 0)
+ goto done;
+ break;
case 0x18 ... 0x1d:
sbb: /* sbb */
emulate_2op_SrcV("sbb", c->src, c->dst, ctxt->eflags);
break;
+ case 0x1e: /* push ds */
+ if (ctxt->mode == X86EMUL_MODE_PROT64)
+ goto cannot_emulate;
+
+ emulate_push_sreg(ctxt, VCPU_SREG_DS);
+ break;
+ case 0x1f: /* pop ds */
+ if (ctxt->mode == X86EMUL_MODE_PROT64)
+ goto cannot_emulate;
+
+ rc = emulate_pop_sreg(ctxt, ops, VCPU_SREG_DS);
+ if (rc != 0)
+ goto done;
+ break;
case 0x20 ... 0x25:
and: /* and */
emulate_2op_SrcV("and", c->src, c->dst, ctxt->eflags);
@@ -2297,6 +2376,14 @@ twobyte_insn:
jmp_rel(c, c->src.val);
c->dst.type = OP_NONE;
break;
+ case 0xa0: /* push fs */
+ emulate_push_sreg(ctxt, VCPU_SREG_FS);
+ break;
+ case 0xa1: /* pop fs */
+ rc = emulate_pop_sreg(ctxt, ops, VCPU_SREG_FS);
+ if (rc != 0)
+ goto done;
+ break;
case 0xa3:
bt: /* bt */
c->dst.type = OP_NONE;
@@ -2308,6 +2395,14 @@ twobyte_insn:
case 0xa5: /* shld cl, r, r/m */
emulate_2op_cl("shld", c->src2, c->src, c->dst, ctxt->eflags);
break;
+ case 0xa8: /* push gs */
+ emulate_push_sreg(ctxt, VCPU_SREG_GS);
+ break;
+ case 0xa9: /* pop gs */
+ rc = emulate_pop_sreg(ctxt, ops, VCPU_SREG_GS);
+ if (rc != 0)
+ goto done;
+ break;
case 0xab:
bts: /* bts */
/* only subword offset */
--
1.6.5.2


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