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Date: Wed, 19 Jul 2017 10:58:59 -0700
From: Thomas Garnier <thgarnie@...gle.com>
To: Russell King <linux@...linux.org.uk>,
Thomas Garnier <thgarnie@...gle.com>,
Thomas Gleixner <tglx@...utronix.de>,
Catalin Marinas <catalin.marinas@....com>,
Will Deacon <will.deacon@....com>,
Dave Martin <Dave.Martin@....com>,
Chris Metcalf <cmetcalf@...lanox.com>,
Pratyush Anand <panand@...hat.com>,
leonard.crestez@....com
Cc: linux-arm-kernel@...ts.infradead.org,
linux-kernel@...r.kernel.org,
kernel-hardening@...ts.openwall.com
Subject: [PATCH 2/3] arm/syscalls: Optimize work flags assembly check
Remove the double branch and use tsteq instead.
Suggested-by: Russell King <linux@...linux.org.uk>
Signed-off-by: Thomas Garnier <thgarnie@...gle.com>
---
arch/arm/kernel/entry-common.S | 7 ++-----
1 file changed, 2 insertions(+), 5 deletions(-)
diff --git a/arch/arm/kernel/entry-common.S b/arch/arm/kernel/entry-common.S
index e33c32d56193..6e094b639d83 100644
--- a/arch/arm/kernel/entry-common.S
+++ b/arch/arm/kernel/entry-common.S
@@ -42,8 +42,7 @@ ret_fast_syscall:
disable_irq_notrace @ disable interrupts
ldr r1, [tsk, #TI_FLAGS] @ re-check for syscall tracing
tst r1, #_TIF_SYSCALL_WORK
- bne fast_work_pending
- tst r1, #_TIF_WORK_MASK
+ tsteq r1, #_TIF_WORK_MASK
bne fast_work_pending
/* perform architecture specific actions before user return */
@@ -70,14 +69,12 @@ ret_fast_syscall:
disable_irq_notrace @ disable interrupts
ldr r1, [tsk, #TI_FLAGS] @ re-check for syscall tracing
tst r1, #_TIF_SYSCALL_WORK
- bne fast_work_pending
- tst r1, #_TIF_WORK_MASK
+ tsteq r1, #_TIF_WORK_MASK
beq no_work_pending
UNWIND(.fnend )
ENDPROC(ret_fast_syscall)
/* Slower path - fall through to work_pending */
-fast_work_pending:
#endif
tst r1, #_TIF_SYSCALL_WORK
--
2.14.0.rc0.284.gd933b75aa4-goog
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