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>

1 files changed, 12 insertions, 12 deletions

diff --git a/arch/arm/mach-tegra/sleep-tegra20.S b/arch/arm/mach-tegra/sleep-tegra20.S
index aaaf3abd2688..be4bc5f853f5 100644
--- a/arch/arm/mach-tegra/sleep-tegra20.S
+++ b/arch/arm/mach-tegra/sleep-tegra20.S
@@ -78,7 +78,7 @@ ENTRY(tegra20_hotplug_shutdown)
 	/* Put this CPU down */
 	cpu_id	r0
 	bl	tegra20_cpu_shutdown
-	mov	pc, lr			@ should never get here
+	ret	lr			@ should never get here
 ENDPROC(tegra20_hotplug_shutdown)
 
 /*
@@ -96,7 +96,7 @@ ENDPROC(tegra20_hotplug_shutdown)
  */
 ENTRY(tegra20_cpu_shutdown)
 	cmp	r0, #0
-	moveq	pc, lr			@ must not be called for CPU 0
+	reteq	lr			@ must not be called for CPU 0
 	mov32	r1, TEGRA_PMC_VIRT + PMC_SCRATCH41
 	mov	r12, #CPU_RESETTABLE
 	str	r12, [r1]
@@ -117,7 +117,7 @@ ENTRY(tegra20_cpu_shutdown)
 	cpu_id	r3
 	cmp	r3, r0
 	beq	.
-	mov	pc, lr
+	ret	lr
 ENDPROC(tegra20_cpu_shutdown)
 #endif
 
@@ -164,7 +164,7 @@ ENTRY(tegra_pen_lock)
 	cmpeq	r12, r0			@ !turn == cpu?
 	beq	1b			@ while !turn == cpu && flag[!cpu] == 1
 
-	mov	pc, lr			@ locked
+	ret	lr			@ locked
 ENDPROC(tegra_pen_lock)
 
 ENTRY(tegra_pen_unlock)
@@ -176,7 +176,7 @@ ENTRY(tegra_pen_unlock)
 	addne	r2, r3, #PMC_SCRATCH39
 	mov	r12, #0
 	str	r12, [r2]
-	mov     pc, lr
+	ret     lr
 ENDPROC(tegra_pen_unlock)
 
 /*
@@ -189,7 +189,7 @@ ENTRY(tegra20_cpu_clear_resettable)
 	mov32	r1, TEGRA_PMC_VIRT + PMC_SCRATCH41
 	mov	r12, #CPU_NOT_RESETTABLE
 	str	r12, [r1]
-	mov	pc, lr
+	ret	lr
 ENDPROC(tegra20_cpu_clear_resettable)
 
 /*
@@ -202,7 +202,7 @@ ENTRY(tegra20_cpu_set_resettable_soon)
 	mov32	r1, TEGRA_PMC_VIRT + PMC_SCRATCH41
 	mov	r12, #CPU_RESETTABLE_SOON
 	str	r12, [r1]
-	mov	pc, lr
+	ret	lr
 ENDPROC(tegra20_cpu_set_resettable_soon)
 
 /*
@@ -217,7 +217,7 @@ ENTRY(tegra20_cpu_is_resettable_soon)
 	cmp	r12, #CPU_RESETTABLE_SOON
 	moveq	r0, #1
 	movne	r0, #0
-	mov	pc, lr
+	ret	lr
 ENDPROC(tegra20_cpu_is_resettable_soon)
 
 /*
@@ -239,7 +239,7 @@ ENTRY(tegra20_sleep_core_finish)
 	mov32	r1, TEGRA_IRAM_LPx_RESUME_AREA
 	add	r0, r0, r1
 
-	mov	pc, r3
+	ret	r3
 ENDPROC(tegra20_sleep_core_finish)
 
 /*
@@ -402,7 +402,7 @@ exit_selfrefresh_loop:
 
 	mov32	r0, TEGRA_PMC_BASE
 	ldr	r0, [r0, #PMC_SCRATCH41]
-	mov	pc, r0			@ jump to tegra_resume
+	ret	r0			@ jump to tegra_resume
 ENDPROC(tegra20_lp1_reset)
 
 /*
@@ -455,7 +455,7 @@ tegra20_switch_cpu_to_clk32k:
 	mov	r0, #0	/* brust policy = 32KHz */
 	str	r0, [r5, #CLK_RESET_SCLK_BURST]
 
-	mov	pc, lr
+	ret	lr
 
 /*
  * tegra20_enter_sleep
@@ -535,7 +535,7 @@ padsave_done:
 	adr	r2, tegra20_sclk_save
 	str	r0, [r2]
 	dsb
-	mov	pc, lr
+	ret	lr
 
 tegra20_sdram_pad_address:
 	.word	TEGRA_APB_MISC_BASE + APB_MISC_XM2CFGCPADCTRL