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| author | Russell King <rmk+kernel@arm.linux.org.uk> | 2014-06-30 16:29:12 +0100 |
|---|---|---|
| committer | Russell King <rmk+kernel@arm.linux.org.uk> | 2014-07-18 12:29:04 +0100 |
| commit | 6ebbf2ce437b33022d30badd49dc94d33ecfa498 (patch) | |
| tree | bc015e35b456a28bb0e501803a454dc0c0d3291a /arch/arm/mm/proc-v6.S | |
| parent | af040ffc9ba1e079ee4c0748aff64fa3d4716fa5 (diff) | |
| download | linux-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-v6.S')
| -rw-r--r-- | arch/arm/mm/proc-v6.S | 16 |
1 files changed, 8 insertions, 8 deletions
diff --git a/arch/arm/mm/proc-v6.S b/arch/arm/mm/proc-v6.S index 32b3558321c4..d0390f4b3f18 100644 --- a/arch/arm/mm/proc-v6.S +++ b/arch/arm/mm/proc-v6.S @@ -36,14 +36,14 @@ #define PMD_FLAGS_SMP PMD_SECT_WBWA|PMD_SECT_S ENTRY(cpu_v6_proc_init) - mov pc, lr + ret lr ENTRY(cpu_v6_proc_fin) mrc p15, 0, r0, c1, c0, 0 @ ctrl register bic r0, r0, #0x1000 @ ...i............ bic r0, r0, #0x0006 @ .............ca. mcr p15, 0, r0, c1, c0, 0 @ disable caches - mov pc, lr + ret lr /* * cpu_v6_reset(loc) @@ -62,7 +62,7 @@ ENTRY(cpu_v6_reset) mcr p15, 0, r1, c1, c0, 0 @ disable MMU mov r1, #0 mcr p15, 0, r1, c7, c5, 4 @ ISB - mov pc, r0 + ret r0 ENDPROC(cpu_v6_reset) .popsection @@ -77,14 +77,14 @@ ENTRY(cpu_v6_do_idle) mov r1, #0 mcr p15, 0, r1, c7, c10, 4 @ DWB - WFI may enter a low-power mode mcr p15, 0, r1, c7, c0, 4 @ wait for interrupt - mov pc, lr + ret lr ENTRY(cpu_v6_dcache_clean_area) 1: mcr p15, 0, r0, c7, c10, 1 @ clean D entry add r0, r0, #D_CACHE_LINE_SIZE subs r1, r1, #D_CACHE_LINE_SIZE bhi 1b - mov pc, lr + ret lr /* * cpu_v6_switch_mm(pgd_phys, tsk) @@ -113,7 +113,7 @@ ENTRY(cpu_v6_switch_mm) #endif mcr p15, 0, r1, c13, c0, 1 @ set context ID #endif - mov pc, lr + ret lr /* * cpu_v6_set_pte_ext(ptep, pte, ext) @@ -131,7 +131,7 @@ ENTRY(cpu_v6_set_pte_ext) #ifdef CONFIG_MMU armv6_set_pte_ext cpu_v6 #endif - mov pc, lr + ret lr /* Suspend/resume support: taken from arch/arm/mach-s3c64xx/sleep.S */ .globl cpu_v6_suspend_size @@ -241,7 +241,7 @@ __v6_setup: mcreq p15, 0, r5, c1, c0, 1 @ write aux control reg orreq r0, r0, #(1 << 21) @ low interrupt latency configuration #endif - mov pc, lr @ return to head.S:__ret + ret lr @ return to head.S:__ret /* * V X F I D LR |