From: Takuya Yoshikawa <yoshikawa.takuya@xxxxxxxxxxxxx>
Recently, emulate_push family functions started to call writeback()
during their emulation. This clearly shows that the usual writeback()
which is done at the end of x86_emulate_insn() cannot cover all cases.
Furthermore, suppressing writeback by changing dst operand's type is
not simple when conditional writeback must be taken care of.
This patch improves this situation a bit by making emulate_push()
itself do writeback and removes scattered writebacks from callers.
This is done by splitting the writeback for OP_MEM case out from
writeback() as a new helper function, writeback_to_mem(), and call it
directly from emulate_push().
Signed-off-by: Takuya Yoshikawa <yoshikawa.takuya@xxxxxxxxxxxxx>
---
arch/x86/kvm/emulate.c | 111 ++++++++++++++++++++---------------------------
1 files changed, 47 insertions(+), 64 deletions(-)
diff --git a/arch/x86/kvm/emulate.c b/arch/x86/kvm/emulate.c
index 8a73805..fe3419a 100644
--- a/arch/x86/kvm/emulate.c
+++ b/arch/x86/kvm/emulate.c
@@ -1069,6 +1069,20 @@ static void write_register_operand(struct operand *op)
}
}
+static int writeback_to_mem(struct x86_emulate_ctxt *ctxt,
+ struct x86_emulate_ops *ops,
+ struct decode_cache *c)
+{
+ if (c->lock_prefix)
+ return ops->cmpxchg_emulated(linear(ctxt, c->dst.addr.mem),
+ &c->dst.orig_val, &c->dst.val, c->dst.bytes,
+ &ctxt->exception, ctxt->vcpu);
+ else
+ return ops->write_emulated(linear(ctxt, c->dst.addr.mem),
+ &c->dst.val, c->dst.bytes,
+ &ctxt->exception, ctxt->vcpu);
+}
+
static inline int writeback(struct x86_emulate_ctxt *ctxt,
struct x86_emulate_ops *ops)
{
@@ -1080,21 +1094,7 @@ static inline int writeback(struct x86_emulate_ctxt *ctxt,
write_register_operand(&c->dst);
break;
case OP_MEM:
- if (c->lock_prefix)
- rc = ops->cmpxchg_emulated(
- linear(ctxt, c->dst.addr.mem),
- &c->dst.orig_val,
- &c->dst.val,
- c->dst.bytes,
- &ctxt->exception,
- ctxt->vcpu);
- else
- rc = ops->write_emulated(
- linear(ctxt, c->dst.addr.mem),
- &c->dst.val,
- c->dst.bytes,
- &ctxt->exception,
- ctxt->vcpu);
+ rc = writeback_to_mem(ctxt, ops, c);
if (rc != X86EMUL_CONTINUE)
return rc;
break;
@@ -1107,17 +1107,21 @@ static inline int writeback(struct x86_emulate_ctxt *ctxt,
return X86EMUL_CONTINUE;
}
-static inline void emulate_push(struct x86_emulate_ctxt *ctxt,
- struct x86_emulate_ops *ops)
+static inline int emulate_push(struct x86_emulate_ctxt *ctxt,
+ struct x86_emulate_ops *ops)
{
struct decode_cache *c = &ctxt->decode;
+ int rc;
- c->dst.type = OP_MEM;
c->dst.bytes = c->op_bytes;
c->dst.val = c->src.val;
register_address_increment(c, &c->regs[VCPU_REGS_RSP], -c->op_bytes);
c->dst.addr.mem.ea = register_address(c, c->regs[VCPU_REGS_RSP]);
c->dst.addr.mem.seg = VCPU_SREG_SS;
+
+ rc = writeback_to_mem(ctxt, ops, c);
+ c->dst.type = OP_NONE;
+ return rc;
}
static int emulate_pop(struct x86_emulate_ctxt *ctxt,
@@ -1179,14 +1183,13 @@ static int emulate_popf(struct x86_emulate_ctxt *ctxt,
return rc;
}
-static void emulate_push_sreg(struct x86_emulate_ctxt *ctxt,
- struct x86_emulate_ops *ops, int seg)
+static int emulate_push_sreg(struct x86_emulate_ctxt *ctxt,
+ struct x86_emulate_ops *ops, int seg)
{
struct decode_cache *c = &ctxt->decode;
c->src.val = ops->get_segment_selector(seg, ctxt->vcpu);
-
- emulate_push(ctxt, ops);
+ return emulate_push(ctxt, ops);
}
static int emulate_pop_sreg(struct x86_emulate_ctxt *ctxt,
@@ -1216,18 +1219,13 @@ static int emulate_pusha(struct x86_emulate_ctxt *ctxt,
(reg == VCPU_REGS_RSP) ?
(c->src.val = old_esp) : (c->src.val = c->regs[reg]);
- emulate_push(ctxt, ops);
-
- rc = writeback(ctxt, ops);
+ rc = emulate_push(ctxt, ops);
if (rc != X86EMUL_CONTINUE)
return rc;
++reg;
}
- /* Disable writeback. */
- c->dst.type = OP_NONE;
-
return rc;
}
@@ -1265,22 +1263,19 @@ int emulate_int_real(struct x86_emulate_ctxt *ctxt,
/* TODO: Add limit checks */
c->src.val = ctxt->eflags;
- emulate_push(ctxt, ops);
- rc = writeback(ctxt, ops);
+ rc = emulate_push(ctxt, ops);
if (rc != X86EMUL_CONTINUE)
return rc;
ctxt->eflags &= ~(EFLG_IF | EFLG_TF | EFLG_AC);
c->src.val = ops->get_segment_selector(VCPU_SREG_CS, ctxt->vcpu);
- emulate_push(ctxt, ops);
- rc = writeback(ctxt, ops);
+ rc = emulate_push(ctxt, ops);
if (rc != X86EMUL_CONTINUE)
return rc;
c->src.val = c->eip;
- emulate_push(ctxt, ops);
- rc = writeback(ctxt, ops);
+ rc = emulate_push(ctxt, ops);
if (rc != X86EMUL_CONTINUE)
return rc;
@@ -1475,6 +1470,7 @@ static inline int emulate_grp45(struct x86_emulate_ctxt *ctxt,
struct x86_emulate_ops *ops)
{
struct decode_cache *c = &ctxt->decode;
+ int rc = X86EMUL_CONTINUE;
switch (c->modrm_reg) {
case 0: /* inc */
@@ -1488,17 +1484,17 @@ static inline int emulate_grp45(struct x86_emulate_ctxt *ctxt,
old_eip = c->eip;
c->eip = c->src.val;
c->src.val = old_eip;
- emulate_push(ctxt, ops);
+ rc = emulate_push(ctxt, ops);
break;
}
case 4: /* jmp abs */
c->eip = c->src.val;
break;
case 6: /* push */
- emulate_push(ctxt, ops);
+ rc = emulate_push(ctxt, ops);
break;
}
- return X86EMUL_CONTINUE;
+ return rc;
}
static inline int emulate_grp9(struct x86_emulate_ctxt *ctxt,
@@ -2142,7 +2138,7 @@ static int emulator_do_task_switch(struct x86_emulate_ctxt *ctxt,
c->op_bytes = c->ad_bytes = (next_tss_desc.type & 8) ? 4 : 2;
c->lock_prefix = 0;
c->src.val = (unsigned long) error_code;
- emulate_push(ctxt, ops);
+ ret = emulate_push(ctxt, ops);
}
return ret;
@@ -2157,16 +2153,12 @@ int emulator_task_switch(struct x86_emulate_ctxt *ctxt,
int rc;
c->eip = ctxt->eip;
- c->dst.type = OP_NONE;
rc = emulator_do_task_switch(ctxt, ops, tss_selector, reason,
has_error_code, error_code);
- if (rc == X86EMUL_CONTINUE) {
- rc = writeback(ctxt, ops);
- if (rc == X86EMUL_CONTINUE)
- ctxt->eip = c->eip;
- }
+ if (rc == X86EMUL_CONTINUE)
+ ctxt->eip = c->eip;
return (rc == X86EMUL_UNHANDLEABLE) ? -1 : 0;
}
@@ -2184,8 +2176,7 @@ static void string_addr_inc(struct x86_emulate_ctxt *ctxt, unsigned seg,
static int em_push(struct x86_emulate_ctxt *ctxt)
{
- emulate_push(ctxt, ctxt->ops);
- return X86EMUL_CONTINUE;
+ return emulate_push(ctxt, ctxt->ops);
}
static int em_das(struct x86_emulate_ctxt *ctxt)
@@ -2245,20 +2236,12 @@ static int em_call_far(struct x86_emulate_ctxt *ctxt)
memcpy(&c->eip, c->src.valptr, c->op_bytes);
c->src.val = old_cs;
- emulate_push(ctxt, ctxt->ops);
- rc = writeback(ctxt, ctxt->ops);
+ rc = emulate_push(ctxt, ctxt->ops);
if (rc != X86EMUL_CONTINUE)
return rc;
c->src.val = old_eip;
- emulate_push(ctxt, ctxt->ops);
- rc = writeback(ctxt, ctxt->ops);
- if (rc != X86EMUL_CONTINUE)
- return rc;
-
- c->dst.type = OP_NONE;
-
- return X86EMUL_CONTINUE;
+ return emulate_push(ctxt, ctxt->ops);
}
static int em_ret_near_imm(struct x86_emulate_ctxt *ctxt)
@@ -3039,7 +3022,7 @@ special_insn:
emulate_2op_SrcV("add", c->src, c->dst, ctxt->eflags);
break;
case 0x06: /* push es */
- emulate_push_sreg(ctxt, ops, VCPU_SREG_ES);
+ rc = emulate_push_sreg(ctxt, ops, VCPU_SREG_ES);
break;
case 0x07: /* pop es */
rc = emulate_pop_sreg(ctxt, ops, VCPU_SREG_ES);
@@ -3049,14 +3032,14 @@ special_insn:
emulate_2op_SrcV("or", c->src, c->dst, ctxt->eflags);
break;
case 0x0e: /* push cs */
- emulate_push_sreg(ctxt, ops, VCPU_SREG_CS);
+ rc = emulate_push_sreg(ctxt, ops, VCPU_SREG_CS);
break;
case 0x10 ... 0x15:
adc: /* adc */
emulate_2op_SrcV("adc", c->src, c->dst, ctxt->eflags);
break;
case 0x16: /* push ss */
- emulate_push_sreg(ctxt, ops, VCPU_SREG_SS);
+ rc = emulate_push_sreg(ctxt, ops, VCPU_SREG_SS);
break;
case 0x17: /* pop ss */
rc = emulate_pop_sreg(ctxt, ops, VCPU_SREG_SS);
@@ -3066,7 +3049,7 @@ special_insn:
emulate_2op_SrcV("sbb", c->src, c->dst, ctxt->eflags);
break;
case 0x1e: /* push ds */
- emulate_push_sreg(ctxt, ops, VCPU_SREG_DS);
+ rc = emulate_push_sreg(ctxt, ops, VCPU_SREG_DS);
break;
case 0x1f: /* pop ds */
rc = emulate_pop_sreg(ctxt, ops, VCPU_SREG_DS);
@@ -3204,7 +3187,7 @@ special_insn:
break;
case 0x9c: /* pushf */
c->src.val = (unsigned long) ctxt->eflags;
- emulate_push(ctxt, ops);
+ rc = emulate_push(ctxt, ops);
break;
case 0x9d: /* popf */
c->dst.type = OP_REG;
@@ -3280,7 +3263,7 @@ special_insn:
long int rel = c->src.val;
c->src.val = (unsigned long) c->eip;
jmp_rel(c, rel);
- emulate_push(ctxt, ops);
+ rc = emulate_push(ctxt, ops);
break;
}
case 0xe9: /* jmp rel */
@@ -3605,7 +3588,7 @@ twobyte_insn:
c->dst.val = test_cc(c->b, ctxt->eflags);
break;
case 0xa0: /* push fs */
- emulate_push_sreg(ctxt, ops, VCPU_SREG_FS);
+ rc = emulate_push_sreg(ctxt, ops, VCPU_SREG_FS);
break;
case 0xa1: /* pop fs */
rc = emulate_pop_sreg(ctxt, ops, VCPU_SREG_FS);
@@ -3622,7 +3605,7 @@ twobyte_insn:
emulate_2op_cl("shld", c->src2, c->src, c->dst, ctxt->eflags);
break;
case 0xa8: /* push gs */
- emulate_push_sreg(ctxt, ops, VCPU_SREG_GS);
+ rc = emulate_push_sreg(ctxt, ops, VCPU_SREG_GS);
break;
case 0xa9: /* pop gs */
rc = emulate_pop_sreg(ctxt, ops, VCPU_SREG_GS);
--
1.7.1
--
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