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authorAvi Kivity <avi@qumranet.com>2008-06-15 22:09:11 -0700
committerAvi Kivity <avi@qumranet.com>2008-07-20 12:42:34 +0300
commitf5b4edcd52e78556800f90d08bfc9126416ac82f (patch)
tree5c40b9781cf18d66c9e71b837ffc3eaddac48ddb /arch
parent84411d85dacdb6665578608c6a70fc8b819761a8 (diff)
KVM: x86 emulator: simplify rip relative decoding
rip relative decoding is relative to the instruction pointer of the next instruction; by moving address adjustment until after decoding is complete, we remove the need to determine the instruction size. Signed-off-by: Avi Kivity <avi@qumranet.com>
Diffstat (limited to 'arch')
-rw-r--r--arch/x86/kvm/x86_emulate.c23
1 files changed, 5 insertions, 18 deletions
diff --git a/arch/x86/kvm/x86_emulate.c b/arch/x86/kvm/x86_emulate.c
index c3a823174f3..20b604489c3 100644
--- a/arch/x86/kvm/x86_emulate.c
+++ b/arch/x86/kvm/x86_emulate.c
@@ -664,7 +664,7 @@ static int decode_modrm(struct x86_emulate_ctxt *ctxt,
{
struct decode_cache *c = &ctxt->decode;
u8 sib;
- int index_reg = 0, base_reg = 0, scale, rip_relative = 0;
+ int index_reg = 0, base_reg = 0, scale;
int rc = 0;
if (c->rex_prefix) {
@@ -754,7 +754,7 @@ static int decode_modrm(struct x86_emulate_ctxt *ctxt,
c->modrm_ea += c->regs[index_reg] << scale;
} else if ((c->modrm_rm & 7) == 5 && c->modrm_mod == 0) {
if (ctxt->mode == X86EMUL_MODE_PROT64)
- rip_relative = 1;
+ c->rip_relative = 1;
} else
c->modrm_ea += c->regs[c->modrm_rm];
switch (c->modrm_mod) {
@@ -770,22 +770,6 @@ static int decode_modrm(struct x86_emulate_ctxt *ctxt,
break;
}
}
- if (rip_relative) {
- c->modrm_ea += c->eip;
- switch (c->d & SrcMask) {
- case SrcImmByte:
- c->modrm_ea += 1;
- break;
- case SrcImm:
- if (c->d & ByteOp)
- c->modrm_ea += 1;
- else
- if (c->op_bytes == 8)
- c->modrm_ea += 4;
- else
- c->modrm_ea += c->op_bytes;
- }
- }
done:
return rc;
}
@@ -1044,6 +1028,9 @@ done_prefixes:
break;
}
+ if (c->rip_relative)
+ c->modrm_ea += c->eip;
+
done:
return (rc == X86EMUL_UNHANDLEABLE) ? -1 : 0;
}