From: Bandan Das <bsd@redhat.com>
To: kvm@vger.kernel.org
Cc: Marcelo Tosatti <mtosatti@redhat.com>,
Paolo Bonzini <pbonzini@redhat.com>,
Gleb Natapov <gleb@kernel.org>,
linux-kernel@vger.kernel.org
Subject: [RFC PATCH v2 3/6] KVM: emulate: cleanup decode_rm
Date: Thu, 10 Apr 2014 20:03:29 -0400 [thread overview]
Message-ID: <1397174612-17373-4-git-send-email-bsd@redhat.com> (raw)
In-Reply-To: <1397174612-17373-1-git-send-email-bsd@redhat.com>
Remove the if conditional - that will help us avoid
an "else initialize to 0" Also, rearrange operators
for slightly better code.
Signed-off-by: Bandan Das <bsd@redhat.com>
---
arch/x86/kvm/emulate.c | 16 +++++++---------
1 file changed, 7 insertions(+), 9 deletions(-)
diff --git a/arch/x86/kvm/emulate.c b/arch/x86/kvm/emulate.c
index a6d9892..9cbaba2 100644
--- a/arch/x86/kvm/emulate.c
+++ b/arch/x86/kvm/emulate.c
@@ -1064,19 +1064,17 @@ static int decode_modrm(struct x86_emulate_ctxt *ctxt,
struct operand *op)
{
u8 sib;
- int index_reg = 0, base_reg = 0, scale;
+ int index_reg, base_reg, scale;
int rc = X86EMUL_CONTINUE;
ulong modrm_ea = 0;
- if (ctxt->rex_prefix) {
- ctxt->modrm_reg = (ctxt->rex_prefix & 4) << 1; /* REX.R */
- index_reg = (ctxt->rex_prefix & 2) << 2; /* REX.X */
- ctxt->modrm_rm = base_reg = (ctxt->rex_prefix & 1) << 3; /* REG.B */
- }
+ index_reg = (ctxt->rex_prefix << 2) & 8; /* REX.X */
+ base_reg = (ctxt->rex_prefix << 3) & 8; /* REG.B */
- ctxt->modrm_mod |= (ctxt->modrm & 0xc0) >> 6;
- ctxt->modrm_reg |= (ctxt->modrm & 0x38) >> 3;
- ctxt->modrm_rm |= (ctxt->modrm & 0x07);
+ ctxt->modrm_mod = (ctxt->modrm & 0xc0) >> 6;
+ ctxt->modrm_reg = ((ctxt->rex_prefix << 1) & 8) | /* REX.R */
+ ((ctxt->modrm & 0x38) >> 3);
+ ctxt->modrm_rm = base_reg | (ctxt->modrm & 0x07);
ctxt->modrm_seg = VCPU_SREG_DS;
if (ctxt->modrm_mod == 3) {
--
1.8.3.1
next prev parent reply other threads:[~2014-04-11 0:04 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-04-11 0:03 [RFC PATCH v2 0/6] Emulator speedups - avoid initializations where possible Bandan Das
2014-04-11 0:03 ` [RFC PATCH v2 1/6] KVM: emulate: move init_decode_cache to emulate.c Bandan Das
2014-04-11 0:03 ` [RFC PATCH v2 2/6] KVM: emulate: Remove ctxt->intercept and ctxt->check_perm checks Bandan Das
2014-04-11 0:03 ` Bandan Das [this message]
2014-04-13 12:51 ` [RFC PATCH v2 3/6] KVM: emulate: cleanup decode_rm Paolo Bonzini
2014-04-11 0:03 ` [RFC PATCH v2 4/6] KVM: emulate: clean up initializations in init_decode_cache Bandan Das
2014-04-11 0:03 ` [RFC PATCH v2 5/6] KVM: emulate: rework seg_override Bandan Das
2014-04-11 0:03 ` [RFC PATCH v2 6/6] KVM: emulate: remove memopp and rip_relative Bandan Das
2014-04-13 12:48 ` Paolo Bonzini
2014-04-14 14:01 ` Bandan Das
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