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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/mm/proc-arm940.S
parentaf040ffc9ba1e079ee4c0748aff64fa3d4716fa5 (diff)
downloadlinux-6ebbf2ce437b33022d30badd49dc94d33ecfa498.tar.bz2
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-König <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/mm/proc-arm940.S')
-rw-r--r--arch/arm/mm/proc-arm940.S24
1 files changed, 12 insertions, 12 deletions
diff --git a/arch/arm/mm/proc-arm940.S b/arch/arm/mm/proc-arm940.S
index 1c39a704ff6e..e5212d489377 100644
--- a/arch/arm/mm/proc-arm940.S
+++ b/arch/arm/mm/proc-arm940.S
@@ -31,7 +31,7 @@
*/
ENTRY(cpu_arm940_proc_init)
ENTRY(cpu_arm940_switch_mm)
- mov pc, lr
+ ret lr
/*
* cpu_arm940_proc_fin()
@@ -41,7 +41,7 @@ ENTRY(cpu_arm940_proc_fin)
bic r0, r0, #0x00001000 @ i-cache
bic r0, r0, #0x00000004 @ d-cache
mcr p15, 0, r0, c1, c0, 0 @ disable caches
- mov pc, lr
+ ret lr
/*
* cpu_arm940_reset(loc)
@@ -58,7 +58,7 @@ ENTRY(cpu_arm940_reset)
bic ip, ip, #0x00000005 @ .............c.p
bic ip, ip, #0x00001000 @ i-cache
mcr p15, 0, ip, c1, c0, 0 @ ctrl register
- mov pc, r0
+ ret r0
ENDPROC(cpu_arm940_reset)
.popsection
@@ -68,7 +68,7 @@ ENDPROC(cpu_arm940_reset)
.align 5
ENTRY(cpu_arm940_do_idle)
mcr p15, 0, r0, c7, c0, 4 @ Wait for interrupt
- mov pc, lr
+ ret lr
/*
* flush_icache_all()
@@ -78,7 +78,7 @@ ENTRY(cpu_arm940_do_idle)
ENTRY(arm940_flush_icache_all)
mov r0, #0
mcr p15, 0, r0, c7, c5, 0 @ invalidate I cache
- mov pc, lr
+ ret lr
ENDPROC(arm940_flush_icache_all)
/*
@@ -122,7 +122,7 @@ ENTRY(arm940_flush_user_cache_range)
tst r2, #VM_EXEC
mcrne p15, 0, ip, c7, c5, 0 @ invalidate I cache
mcrne p15, 0, ip, c7, c10, 4 @ drain WB
- mov pc, lr
+ ret lr
/*
* coherent_kern_range(start, end)
@@ -170,7 +170,7 @@ ENTRY(arm940_flush_kern_dcache_area)
bcs 1b @ segments 7 to 0
mcr p15, 0, r0, c7, c5, 0 @ invalidate I cache
mcr p15, 0, r0, c7, c10, 4 @ drain WB
- mov pc, lr
+ ret lr
/*
* dma_inv_range(start, end)
@@ -191,7 +191,7 @@ arm940_dma_inv_range:
subs r1, r1, #1 << 4
bcs 1b @ segments 7 to 0
mcr p15, 0, ip, c7, c10, 4 @ drain WB
- mov pc, lr
+ ret lr
/*
* dma_clean_range(start, end)
@@ -215,7 +215,7 @@ ENTRY(cpu_arm940_dcache_clean_area)
bcs 1b @ segments 7 to 0
#endif
mcr p15, 0, ip, c7, c10, 4 @ drain WB
- mov pc, lr
+ ret lr
/*
* dma_flush_range(start, end)
@@ -241,7 +241,7 @@ ENTRY(arm940_dma_flush_range)
subs r1, r1, #1 << 4
bcs 1b @ segments 7 to 0
mcr p15, 0, ip, c7, c10, 4 @ drain WB
- mov pc, lr
+ ret lr
/*
* dma_map_area(start, size, dir)
@@ -264,7 +264,7 @@ ENDPROC(arm940_dma_map_area)
* - dir - DMA direction
*/
ENTRY(arm940_dma_unmap_area)
- mov pc, lr
+ ret lr
ENDPROC(arm940_dma_unmap_area)
.globl arm940_flush_kern_cache_louis
@@ -337,7 +337,7 @@ __arm940_setup:
orr r0, r0, #0x00001000 @ I-cache
orr r0, r0, #0x00000005 @ MPU/D-cache
- mov pc, lr
+ ret lr
.size __arm940_setup, . - __arm940_setup