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authorRussell King <rmk+kernel@arm.linux.org.uk>2014-06-30 16:29:12 +0100
committerRussell King <rmk+kernel@arm.linux.org.uk>2014-07-18 12:29:04 +0100
commit6ebbf2ce437b33022d30badd49dc94d33ecfa498 (patch)
treebc015e35b456a28bb0e501803a454dc0c0d3291a /arch/arm/mach-s3c24xx
parentaf040ffc9ba1e079ee4c0748aff64fa3d4716fa5 (diff)
downloadlinux-linaro-stable-6ebbf2ce437b33022d30badd49dc94d33ecfa498.tar.gz
ARM: convert all "mov.* pc, reg" to "bx reg" for ARMv6+
ARMv6 and greater introduced a new instruction ("bx") which can be used to return from function calls. Recent CPUs perform better when the "bx lr" instruction is used rather than the "mov pc, lr" instruction, and this sequence is strongly recommended to be used by the ARM architecture manual (section A.4.1.1). We provide a new macro "ret" with all its variants for the condition code which will resolve to the appropriate instruction. Rather than doing this piecemeal, and miss some instances, change all the "mov pc" instances to use the new macro, with the exception of the "movs" instruction and the kprobes code. This allows us to detect the "mov pc, lr" case and fix it up - and also gives us the possibility of deploying this for other registers depending on the CPU selection. Reported-by: Will Deacon <will.deacon@arm.com> Tested-by: Stephen Warren <swarren@nvidia.com> # Tegra Jetson TK1 Tested-by: Robert Jarzmik <robert.jarzmik@free.fr> # mioa701_bootresume.S Tested-by: Andrew Lunn <andrew@lunn.ch> # Kirkwood Tested-by: Shawn Guo <shawn.guo@freescale.com> Tested-by: Tony Lindgren <tony@atomide.com> # OMAPs Tested-by: Gregory CLEMENT <gregory.clement@free-electrons.com> # Armada XP, 375, 385 Acked-by: Sekhar Nori <nsekhar@ti.com> # DaVinci Acked-by: Christoffer Dall <christoffer.dall@linaro.org> # kvm/hyp Acked-by: Haojian Zhuang <haojian.zhuang@gmail.com> # PXA3xx Acked-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com> # Xen Tested-by: Uwe Kleine-K├Ânig <u.kleine-koenig@pengutronix.de> # ARMv7M Tested-by: Simon Horman <horms+renesas@verge.net.au> # Shmobile Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Diffstat (limited to 'arch/arm/mach-s3c24xx')
-rw-r--r--arch/arm/mach-s3c24xx/sleep-s3c2410.S2
-rw-r--r--arch/arm/mach-s3c24xx/sleep-s3c2412.S2
2 files changed, 2 insertions, 2 deletions
diff --git a/arch/arm/mach-s3c24xx/sleep-s3c2410.S b/arch/arm/mach-s3c24xx/sleep-s3c2410.S
index c9b91223697c..875ba8911127 100644
--- a/arch/arm/mach-s3c24xx/sleep-s3c2410.S
+++ b/arch/arm/mach-s3c24xx/sleep-s3c2410.S
@@ -66,4 +66,4 @@ s3c2410_do_sleep:
streq r8, [r5] @ SDRAM power-down config
streq r9, [r6] @ CPU sleep
1: beq 1b
- mov pc, r14
+ ret lr
diff --git a/arch/arm/mach-s3c24xx/sleep-s3c2412.S b/arch/arm/mach-s3c24xx/sleep-s3c2412.S
index 5adaceb7da13..6bf5b4d8743c 100644
--- a/arch/arm/mach-s3c24xx/sleep-s3c2412.S
+++ b/arch/arm/mach-s3c24xx/sleep-s3c2412.S
@@ -65,4 +65,4 @@ s3c2412_sleep_enter1:
strne r9, [r3]
bne s3c2412_sleep_enter1
- mov pc, r14
+ ret lr