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>

3 files changed, 23 insertions, 23 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
diff --git a/arch/arm/mach-tegra/sleep-tegra30.S b/arch/arm/mach-tegra/sleep-tegra30.S
index b16d4a57fa59..09cad9b071de 100644
--- a/arch/arm/mach-tegra/sleep-tegra30.S
+++ b/arch/arm/mach-tegra/sleep-tegra30.S
@@ -142,7 +142,7 @@ ENTRY(tegra30_hotplug_shutdown)
         /* Powergate this CPU */
         mov     r0, #TEGRA30_POWER_HOTPLUG_SHUTDOWN
         bl      tegra30_cpu_shutdown
-        mov     pc, lr                  @ should never get here
+        ret     lr                      @ should never get here
 ENDPROC(tegra30_hotplug_shutdown)
 
 /*
@@ -161,7 +161,7 @@ ENTRY(tegra30_cpu_shutdown)
         bne     _no_cpu0_chk    @ It's not Tegra30
 
         cmp     r3, #0
-        moveq   pc, lr          @ Must never be called for CPU 0
+        reteq   lr              @ Must never be called for CPU 0
 _no_cpu0_chk:
 
         ldr     r12, =TEGRA_FLOW_CTRL_VIRT
@@ -266,7 +266,7 @@ ENTRY(tegra30_sleep_core_finish)
         mov32   r1, TEGRA_IRAM_LPx_RESUME_AREA
         add     r0, r0, r1
 
-        mov     pc, r3
+        ret     r3
 ENDPROC(tegra30_sleep_core_finish)
 
 /*
@@ -285,7 +285,7 @@ ENTRY(tegra30_sleep_cpu_secondary_finish)
         mov     r0, #0                          @ power mode flags (!hotplug)
         bl      tegra30_cpu_shutdown
         mov     r0, #1                          @ never return here
-        mov     pc, r7
+        ret     r7
 ENDPROC(tegra30_sleep_cpu_secondary_finish)
 
 /*
@@ -529,7 +529,7 @@ __no_dual_emc_chanl:
 
         mov32   r0, TEGRA_PMC_BASE
         ldr     r0, [r0, #PMC_SCRATCH41]
-        mov     pc, r0                  @ jump to tegra_resume
+        ret     r0                      @ jump to tegra_resume
 ENDPROC(tegra30_lp1_reset)
 
         .align  L1_CACHE_SHIFT
@@ -659,7 +659,7 @@ _no_pll_in_iddq:
         mov     r0, #0  /* brust policy = 32KHz */
         str     r0, [r5, #CLK_RESET_SCLK_BURST]
 
-        mov     pc, lr
+        ret     lr
 
 /*
  * tegra30_enter_sleep
@@ -819,7 +819,7 @@ pmc_io_dpd_skip:
 
         dsb
 
-        mov     pc, lr
+        ret     lr
 
         .ltorg
 /* dummy symbol for end of IRAM */
diff --git a/arch/arm/mach-tegra/sleep.S b/arch/arm/mach-tegra/sleep.S
index 8d06213fbc47..f024a5109e8e 100644
--- a/arch/arm/mach-tegra/sleep.S
+++ b/arch/arm/mach-tegra/sleep.S
@@ -87,7 +87,7 @@ ENTRY(tegra_init_l2_for_a15)
         mcrne   p15, 0x1, r0, c9, c0, 2
 _exit_init_l2_a15:
 
-        mov     pc, lr
+        ret     lr
 ENDPROC(tegra_init_l2_for_a15)
 
 /*
@@ -111,7 +111,7 @@ ENTRY(tegra_sleep_cpu_finish)
         add     r3, r3, r0
         mov     r0, r1
 
-        mov     pc, r3
+        ret     r3
 ENDPROC(tegra_sleep_cpu_finish)
 
 /*
@@ -139,7 +139,7 @@ ENTRY(tegra_shut_off_mmu)
         moveq   r3, #0
         streq   r3, [r2, #L2X0_CTRL]
 #endif
-        mov     pc, r0
+        ret     r0
 ENDPROC(tegra_shut_off_mmu)
         .popsection
 
@@ -156,6 +156,6 @@ ENTRY(tegra_switch_cpu_to_pllp)
         str     r0, [r5, #CLK_RESET_CCLK_BURST]
         mov     r0, #0
         str     r0, [r5, #CLK_RESET_CCLK_DIVIDER]
-        mov     pc, lr
+        ret     lr
 ENDPROC(tegra_switch_cpu_to_pllp)
 #endif