From: marc.zyngier@arm.com (Marc Zyngier)
To: linux-arm-kernel@lists.infradead.org
Subject: [PATCH] ARM: KVM: avoid add/sub on vcpu pointer
Date: Tue, 15 Jan 2013 11:20:29 +0000 [thread overview]
Message-ID: <1358248829-13764-1-git-send-email-marc.zyngier@arm.com> (raw)
Doing arithmetic on the vcpu pointer can be avoided by using
another register as a base. Saves a few instructions on the
switch path.
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
---
arch/arm/kvm/interrupts_head.S | 32 ++++++++++++++------------------
1 file changed, 14 insertions(+), 18 deletions(-)
diff --git a/arch/arm/kvm/interrupts_head.S b/arch/arm/kvm/interrupts_head.S
index 0e423be..d2442f9 100644
--- a/arch/arm/kvm/interrupts_head.S
+++ b/arch/arm/kvm/interrupts_head.S
@@ -264,11 +264,10 @@ vcpu .req r0 @ vcpu pointer always in r0
str r3, [vcpu, #CP15_OFFSET(c1_CPACR)]
str r4, [vcpu, #CP15_OFFSET(c2_TTBCR)]
str r5, [vcpu, #CP15_OFFSET(c3_DACR)]
- add vcpu, vcpu, #CP15_OFFSET(c2_TTBR0)
- strd r6, r7, [vcpu]
- add vcpu, vcpu, #CP15_OFFSET(c2_TTBR1) - CP15_OFFSET(c2_TTBR0)
- strd r8, r9, [vcpu]
- sub vcpu, vcpu, #CP15_OFFSET(c2_TTBR1)
+ add r2, vcpu, #CP15_OFFSET(c2_TTBR0)
+ strd r6, r7, [r2]
+ add r2, vcpu, #CP15_OFFSET(c2_TTBR1)
+ strd r8, r9, [r2]
str r10, [vcpu, #CP15_OFFSET(c10_PRRR)]
str r11, [vcpu, #CP15_OFFSET(c10_NMRR)]
str r12, [vcpu, #CP15_OFFSET(c0_CSSELR)]
@@ -362,11 +361,10 @@ vcpu .req r0 @ vcpu pointer always in r0
ldr r3, [vcpu, #CP15_OFFSET(c1_CPACR)]
ldr r4, [vcpu, #CP15_OFFSET(c2_TTBCR)]
ldr r5, [vcpu, #CP15_OFFSET(c3_DACR)]
- add vcpu, vcpu, #CP15_OFFSET(c2_TTBR0)
- ldrd r6, r7, [vcpu]
- add vcpu, vcpu, #CP15_OFFSET(c2_TTBR1) - CP15_OFFSET(c2_TTBR0)
- ldrd r8, r9, [vcpu]
- sub vcpu, vcpu, #CP15_OFFSET(c2_TTBR1)
+ add r12, vcpu, #CP15_OFFSET(c2_TTBR0)
+ ldrd r6, r7, [r12]
+ add r12, vcpu, #CP15_OFFSET(c2_TTBR1)
+ ldrd r8, r9, [r12]
ldr r10, [vcpu, #CP15_OFFSET(c10_PRRR)]
ldr r11, [vcpu, #CP15_OFFSET(c10_NMRR)]
ldr r12, [vcpu, #CP15_OFFSET(c0_CSSELR)]
@@ -479,7 +477,7 @@ vcpu .req r0 @ vcpu pointer always in r0
* for the host.
*
* Assumes vcpu pointer in vcpu reg
- * Clobbers r2-r4
+ * Clobbers r2-r5
*/
.macro save_timer_state
#ifdef CONFIG_KVM_ARM_TIMER
@@ -496,9 +494,8 @@ vcpu .req r0 @ vcpu pointer always in r0
mrrc p15, 3, r2, r3, c14 @ CNTV_CVAL
ldr r4, =VCPU_TIMER_CNTV_CVAL
- add vcpu, vcpu, r4
- strd r2, r3, [vcpu]
- sub vcpu, vcpu, r4
+ add r5, vcpu, r4
+ strd r2, r3, [r5]
1:
#endif
@@ -513,7 +510,7 @@ vcpu .req r0 @ vcpu pointer always in r0
* for the host.
*
* Assumes vcpu pointer in vcpu reg
- * Clobbers r2-r4
+ * Clobbers r2-r5
*/
.macro restore_timer_state
@ Disallow physical timer access for the guest
@@ -534,9 +531,8 @@ vcpu .req r0 @ vcpu pointer always in r0
mcrr p15, 4, r2, r3, c14 @ CNTVOFF
ldr r4, =VCPU_TIMER_CNTV_CVAL
- add vcpu, vcpu, r4
- ldrd r2, r3, [vcpu]
- sub vcpu, vcpu, r4
+ add r5, vcpu, r4
+ ldrd r2, r3, [r5]
mcrr p15, 3, r2, r3, c14 @ CNTV_CVAL
isb
--
1.8.1
next reply other threads:[~2013-01-15 11:20 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-01-15 11:20 Marc Zyngier [this message]
2013-01-15 14:35 ` [PATCH] ARM: KVM: avoid add/sub on vcpu pointer Christoffer Dall
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