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KVM: x86 emulator: Use ctxt->_eip directly in do_insn_fetch_byte()
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Instead of passing ctxt->_eip from insn_fetch() call sites, get it from
ctxt in do_insn_fetch_byte().  This is done by replacing the argument
_eip of insn_fetch() with _ctxt, which should be better than letting the
macro use ctxt silently in its body.

Though this changes the place where ctxt->_eip is incremented from
insn_fetch() to do_insn_fetch_byte(), this does not have any real
effect.

Signed-off-by: Takuya Yoshikawa <yoshikawa.takuya@oss.ntt.co.jp>
Signed-off-by: Avi Kivity <avi@redhat.com>
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Takuya Yoshikawa authored and Avi Kivity committed Sep 25, 2011
1 parent 743eeb0 commit 807941b
Showing 1 changed file with 43 additions and 36 deletions.
79 changes: 43 additions & 36 deletions arch/x86/kvm/emulate.c
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Original file line number Diff line number Diff line change
Expand Up @@ -651,18 +651,26 @@ static int segmented_read_std(struct x86_emulate_ctxt *ctxt,
return ctxt->ops->read_std(ctxt, linear, data, size, &ctxt->exception);
}

static int do_insn_fetch_byte(struct x86_emulate_ctxt *ctxt,
unsigned long eip, u8 *dest)
/*
* Fetch the next byte of the instruction being emulated which is pointed to
* by ctxt->_eip, then increment ctxt->_eip.
*
* Also prefetch the remaining bytes of the instruction without crossing page
* boundary if they are not in fetch_cache yet.
*/
static int do_insn_fetch_byte(struct x86_emulate_ctxt *ctxt, u8 *dest)
{
struct fetch_cache *fc = &ctxt->fetch;
int rc;
int size, cur_size;

if (eip == fc->end) {
if (ctxt->_eip == fc->end) {
unsigned long linear;
struct segmented_address addr = { .seg=VCPU_SREG_CS, .ea=eip};
struct segmented_address addr = { .seg = VCPU_SREG_CS,
.ea = ctxt->_eip };
cur_size = fc->end - fc->start;
size = min(15UL - cur_size, PAGE_SIZE - offset_in_page(eip));
size = min(15UL - cur_size,
PAGE_SIZE - offset_in_page(ctxt->_eip));
rc = __linearize(ctxt, addr, size, false, true, &linear);
if (rc != X86EMUL_CONTINUE)
return rc;
Expand All @@ -672,41 +680,40 @@ static int do_insn_fetch_byte(struct x86_emulate_ctxt *ctxt,
return rc;
fc->end += size;
}
*dest = fc->data[eip - fc->start];
*dest = fc->data[ctxt->_eip - fc->start];
ctxt->_eip++;
return X86EMUL_CONTINUE;
}

static int do_insn_fetch(struct x86_emulate_ctxt *ctxt,
unsigned long eip, void *dest, unsigned size)
void *dest, unsigned size)
{
int rc;

/* x86 instructions are limited to 15 bytes. */
if (eip + size - ctxt->eip > 15)
if (ctxt->_eip + size - ctxt->eip > 15)
return X86EMUL_UNHANDLEABLE;
while (size--) {
rc = do_insn_fetch_byte(ctxt, eip++, dest++);
rc = do_insn_fetch_byte(ctxt, dest++);
if (rc != X86EMUL_CONTINUE)
return rc;
}
return X86EMUL_CONTINUE;
}

/* Fetch next part of the instruction being emulated. */
#define insn_fetch(_type, _size, _eip) \
#define insn_fetch(_type, _size, _ctxt) \
({ unsigned long _x; \
rc = do_insn_fetch(ctxt, (_eip), &_x, (_size)); \
rc = do_insn_fetch(_ctxt, &_x, (_size)); \
if (rc != X86EMUL_CONTINUE) \
goto done; \
(_eip) += (_size); \
(_type)_x; \
})

#define insn_fetch_arr(_arr, _size, _eip) \
({ rc = do_insn_fetch(ctxt, (_eip), _arr, (_size)); \
#define insn_fetch_arr(_arr, _size, _ctxt) \
({ rc = do_insn_fetch(_ctxt, _arr, (_size)); \
if (rc != X86EMUL_CONTINUE) \
goto done; \
(_eip) += (_size); \
})

/*
Expand Down Expand Up @@ -894,7 +901,7 @@ static int decode_modrm(struct x86_emulate_ctxt *ctxt,
ctxt->modrm_rm = base_reg = (ctxt->rex_prefix & 1) << 3; /* REG.B */
}

ctxt->modrm = insn_fetch(u8, 1, ctxt->_eip);
ctxt->modrm = insn_fetch(u8, 1, ctxt);
ctxt->modrm_mod |= (ctxt->modrm & 0xc0) >> 6;
ctxt->modrm_reg |= (ctxt->modrm & 0x38) >> 3;
ctxt->modrm_rm |= (ctxt->modrm & 0x07);
Expand Down Expand Up @@ -928,13 +935,13 @@ static int decode_modrm(struct x86_emulate_ctxt *ctxt,
switch (ctxt->modrm_mod) {
case 0:
if (ctxt->modrm_rm == 6)
modrm_ea += insn_fetch(u16, 2, ctxt->_eip);
modrm_ea += insn_fetch(u16, 2, ctxt);
break;
case 1:
modrm_ea += insn_fetch(s8, 1, ctxt->_eip);
modrm_ea += insn_fetch(s8, 1, ctxt);
break;
case 2:
modrm_ea += insn_fetch(u16, 2, ctxt->_eip);
modrm_ea += insn_fetch(u16, 2, ctxt);
break;
}
switch (ctxt->modrm_rm) {
Expand Down Expand Up @@ -971,13 +978,13 @@ static int decode_modrm(struct x86_emulate_ctxt *ctxt,
} else {
/* 32/64-bit ModR/M decode. */
if ((ctxt->modrm_rm & 7) == 4) {
sib = insn_fetch(u8, 1, ctxt->_eip);
sib = insn_fetch(u8, 1, ctxt);
index_reg |= (sib >> 3) & 7;
base_reg |= sib & 7;
scale = sib >> 6;

if ((base_reg & 7) == 5 && ctxt->modrm_mod == 0)
modrm_ea += insn_fetch(s32, 4, ctxt->_eip);
modrm_ea += insn_fetch(s32, 4, ctxt);
else
modrm_ea += ctxt->regs[base_reg];
if (index_reg != 4)
Expand All @@ -990,13 +997,13 @@ static int decode_modrm(struct x86_emulate_ctxt *ctxt,
switch (ctxt->modrm_mod) {
case 0:
if (ctxt->modrm_rm == 5)
modrm_ea += insn_fetch(s32, 4, ctxt->_eip);
modrm_ea += insn_fetch(s32, 4, ctxt);
break;
case 1:
modrm_ea += insn_fetch(s8, 1, ctxt->_eip);
modrm_ea += insn_fetch(s8, 1, ctxt);
break;
case 2:
modrm_ea += insn_fetch(s32, 4, ctxt->_eip);
modrm_ea += insn_fetch(s32, 4, ctxt);
break;
}
}
Expand All @@ -1013,13 +1020,13 @@ static int decode_abs(struct x86_emulate_ctxt *ctxt,
op->type = OP_MEM;
switch (ctxt->ad_bytes) {
case 2:
op->addr.mem.ea = insn_fetch(u16, 2, ctxt->_eip);
op->addr.mem.ea = insn_fetch(u16, 2, ctxt);
break;
case 4:
op->addr.mem.ea = insn_fetch(u32, 4, ctxt->_eip);
op->addr.mem.ea = insn_fetch(u32, 4, ctxt);
break;
case 8:
op->addr.mem.ea = insn_fetch(u64, 8, ctxt->_eip);
op->addr.mem.ea = insn_fetch(u64, 8, ctxt);
break;
}
done:
Expand Down Expand Up @@ -3309,13 +3316,13 @@ static int decode_imm(struct x86_emulate_ctxt *ctxt, struct operand *op,
/* NB. Immediates are sign-extended as necessary. */
switch (op->bytes) {
case 1:
op->val = insn_fetch(s8, 1, ctxt->_eip);
op->val = insn_fetch(s8, 1, ctxt);
break;
case 2:
op->val = insn_fetch(s16, 2, ctxt->_eip);
op->val = insn_fetch(s16, 2, ctxt);
break;
case 4:
op->val = insn_fetch(s32, 4, ctxt->_eip);
op->val = insn_fetch(s32, 4, ctxt);
break;
}
if (!sign_extension) {
Expand Down Expand Up @@ -3374,7 +3381,7 @@ int x86_decode_insn(struct x86_emulate_ctxt *ctxt, void *insn, int insn_len)

/* Legacy prefixes. */
for (;;) {
switch (ctxt->b = insn_fetch(u8, 1, ctxt->_eip)) {
switch (ctxt->b = insn_fetch(u8, 1, ctxt)) {
case 0x66: /* operand-size override */
op_prefix = true;
/* switch between 2/4 bytes */
Expand Down Expand Up @@ -3430,21 +3437,21 @@ int x86_decode_insn(struct x86_emulate_ctxt *ctxt, void *insn, int insn_len)
/* Two-byte opcode? */
if (ctxt->b == 0x0f) {
ctxt->twobyte = 1;
ctxt->b = insn_fetch(u8, 1, ctxt->_eip);
ctxt->b = insn_fetch(u8, 1, ctxt);
opcode = twobyte_table[ctxt->b];
}
ctxt->d = opcode.flags;

while (ctxt->d & GroupMask) {
switch (ctxt->d & GroupMask) {
case Group:
ctxt->modrm = insn_fetch(u8, 1, ctxt->_eip);
ctxt->modrm = insn_fetch(u8, 1, ctxt);
--ctxt->_eip;
goffset = (ctxt->modrm >> 3) & 7;
opcode = opcode.u.group[goffset];
break;
case GroupDual:
ctxt->modrm = insn_fetch(u8, 1, ctxt->_eip);
ctxt->modrm = insn_fetch(u8, 1, ctxt);
--ctxt->_eip;
goffset = (ctxt->modrm >> 3) & 7;
if ((ctxt->modrm >> 6) == 3)
Expand Down Expand Up @@ -3577,7 +3584,7 @@ int x86_decode_insn(struct x86_emulate_ctxt *ctxt, void *insn, int insn_len)
ctxt->src.type = OP_IMM;
ctxt->src.addr.mem.ea = ctxt->_eip;
ctxt->src.bytes = ctxt->op_bytes + 2;
insn_fetch_arr(ctxt->src.valptr, ctxt->src.bytes, ctxt->_eip);
insn_fetch_arr(ctxt->src.valptr, ctxt->src.bytes, ctxt);
break;
case SrcMemFAddr:
memop.bytes = ctxt->op_bytes + 2;
Expand Down Expand Up @@ -3630,7 +3637,7 @@ int x86_decode_insn(struct x86_emulate_ctxt *ctxt, void *insn, int insn_len)
ctxt->dst.type = OP_IMM;
ctxt->dst.addr.mem.ea = ctxt->_eip;
ctxt->dst.bytes = 1;
ctxt->dst.val = insn_fetch(u8, 1, ctxt->_eip);
ctxt->dst.val = insn_fetch(u8, 1, ctxt);
break;
case DstMem:
case DstMem64:
Expand Down

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