KVM: x86 emulator: Use ctxt->_eip directly in do_insn_fetch_byte()

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>

diff --git a/arch/x86/kvm/emulate.c b/arch/x86/kvm/emulate.c
index 8b4cc5f..ce48dc4 100644 (file)
--- a/arch/x86/kvm/emulate.c
+++ b/arch/x86/kvm/emulate.c
@@ -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;
@@ -672,20 +680,21 @@ 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;
        }
@@ -693,20 +702,18 @@ static int do_insn_fetch(struct x86_emulate_ctxt *ctxt,
 }
 
 /* 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);                                              \
 })
 
 /*
@@ -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);
@@ -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) {
@@ -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)
@@ -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;
                }
        }
@@ -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:
@@ -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) {
@@ -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 */
@@ -3430,7 +3437,7 @@ done_prefixes:
        /* 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;
@@ -3438,13 +3445,13 @@ done_prefixes:
        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)
@@ -3577,7 +3584,7 @@ done_prefixes:
                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;
@@ -3630,7 +3637,7 @@ done_prefixes:
                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: