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ARM: convert all "mov.* pc, reg" to "bx reg" for ARMv6+

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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>
This commit is contained in:
Russell King
2014-06-30 16:29:12 +01:00
parent af040ffc9b
commit 6ebbf2ce43
106 changed files with 644 additions and 607 deletions
Download Patch File Download Diff File Expand all files Collapse all files

16
arch/arm/mm/proc-arm720.S
View File

@@ -51,14 +51,14 @@
*/
ENTRY(cpu_arm720_dcache_clean_area)
ENTRY(cpu_arm720_proc_init)
mov pc, lr
ret lr
ENTRY(cpu_arm720_proc_fin)
mrc p15, 0, r0, c1, c0, 0
bic r0, r0, #0x1000 @ ...i............
bic r0, r0, #0x000e @ ............wca.
mcr p15, 0, r0, c1, c0, 0 @ disable caches
mov pc, lr
ret lr
/*
* Function: arm720_proc_do_idle(void)
@@ -66,7 +66,7 @@ ENTRY(cpu_arm720_proc_fin)
* Purpose : put the processor in proper idle mode
*/
ENTRY(cpu_arm720_do_idle)
mov pc, lr
ret lr
/*
* Function: arm720_switch_mm(unsigned long pgd_phys)
@@ -81,7 +81,7 @@ ENTRY(cpu_arm720_switch_mm)
mcr p15, 0, r0, c2, c0, 0 @ update page table ptr
mcr p15, 0, r1, c8, c7, 0 @ flush TLB (v4)
#endif
mov pc, lr
ret lr
/*
* Function: arm720_set_pte_ext(pte_t *ptep, pte_t pte, unsigned int ext)
@@ -94,7 +94,7 @@ ENTRY(cpu_arm720_set_pte_ext)
#ifdef CONFIG_MMU
armv3_set_pte_ext wc_disable=0
#endif
mov pc, lr
ret lr
/*
* Function: arm720_reset
@@ -112,7 +112,7 @@ ENTRY(cpu_arm720_reset)
bic ip, ip, #0x000f @ ............wcam
bic ip, ip, #0x2100 @ ..v....s........
mcr p15, 0, ip, c1, c0, 0 @ ctrl register
mov pc, r0
ret r0
ENDPROC(cpu_arm720_reset)
.popsection
@@ -128,7 +128,7 @@ __arm710_setup:
bic r0, r0, r5
ldr r5, arm710_cr1_set
orr r0, r0, r5
mov pc, lr @ __ret (head.S)
ret lr @ __ret (head.S)
.size __arm710_setup, . - __arm710_setup
/*
@@ -156,7 +156,7 @@ __arm720_setup:
mrc p15, 0, r0, c1, c0 @ get control register
bic r0, r0, r5
orr r0, r0, r6
mov pc, lr @ __ret (head.S)
ret lr @ __ret (head.S)
.size __arm720_setup, . - __arm720_setup
/*