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>
diff --git a/arch/arm/kernel/debug.S b/arch/arm/kernel/debug.S
index 14f7c3b1..78c91b5 100644
--- a/arch/arm/kernel/debug.S
+++ b/arch/arm/kernel/debug.S
@@ -90,7 +90,7 @@
ldrneb r1, [r0], #1
teqne r1, #0
bne 1b
- mov pc, lr
+ ret lr
ENDPROC(printascii)
ENTRY(printch)
@@ -105,7 +105,7 @@
addruart r2, r3, ip
str r2, [r0]
str r3, [r1]
- mov pc, lr
+ ret lr
ENDPROC(debug_ll_addr)
#endif
@@ -116,7 +116,7 @@
mov r0, #0x04 @ SYS_WRITE0
ARM( svc #0x123456 )
THUMB( svc #0xab )
- mov pc, lr
+ ret lr
ENDPROC(printascii)
ENTRY(printch)
@@ -125,14 +125,14 @@
mov r0, #0x03 @ SYS_WRITEC
ARM( svc #0x123456 )
THUMB( svc #0xab )
- mov pc, lr
+ ret lr
ENDPROC(printch)
ENTRY(debug_ll_addr)
mov r2, #0
str r2, [r0]
str r2, [r1]
- mov pc, lr
+ ret lr
ENDPROC(debug_ll_addr)
#endif
diff --git a/arch/arm/kernel/entry-armv.S b/arch/arm/kernel/entry-armv.S
index 52a949a..36276cd 100644
--- a/arch/arm/kernel/entry-armv.S
+++ b/arch/arm/kernel/entry-armv.S
@@ -224,7 +224,7 @@
1: bl preempt_schedule_irq @ irq en/disable is done inside
ldr r0, [tsk, #TI_FLAGS] @ get new tasks TI_FLAGS
tst r0, #_TIF_NEED_RESCHED
- moveq pc, r8 @ go again
+ reteq r8 @ go again
b 1b
#endif
@@ -490,7 +490,7 @@
.pushsection .fixup, "ax"
.align 2
4: str r4, [sp, #S_PC] @ retry current instruction
- mov pc, r9
+ ret r9
.popsection
.pushsection __ex_table,"a"
.long 1b, 4b
@@ -552,7 +552,7 @@
#endif
tst r0, #0x08000000 @ only CDP/CPRT/LDC/STC have bit 27
tstne r0, #0x04000000 @ bit 26 set on both ARM and Thumb-2
- moveq pc, lr
+ reteq lr
and r8, r0, #0x00000f00 @ mask out CP number
THUMB( lsr r8, r8, #8 )
mov r7, #1
@@ -571,33 +571,33 @@
THUMB( add pc, r8 )
nop
- movw_pc lr @ CP#0
+ ret.w lr @ CP#0
W(b) do_fpe @ CP#1 (FPE)
W(b) do_fpe @ CP#2 (FPE)
- movw_pc lr @ CP#3
+ ret.w lr @ CP#3
#ifdef CONFIG_CRUNCH
b crunch_task_enable @ CP#4 (MaverickCrunch)
b crunch_task_enable @ CP#5 (MaverickCrunch)
b crunch_task_enable @ CP#6 (MaverickCrunch)
#else
- movw_pc lr @ CP#4
- movw_pc lr @ CP#5
- movw_pc lr @ CP#6
+ ret.w lr @ CP#4
+ ret.w lr @ CP#5
+ ret.w lr @ CP#6
#endif
- movw_pc lr @ CP#7
- movw_pc lr @ CP#8
- movw_pc lr @ CP#9
+ ret.w lr @ CP#7
+ ret.w lr @ CP#8
+ ret.w lr @ CP#9
#ifdef CONFIG_VFP
W(b) do_vfp @ CP#10 (VFP)
W(b) do_vfp @ CP#11 (VFP)
#else
- movw_pc lr @ CP#10 (VFP)
- movw_pc lr @ CP#11 (VFP)
+ ret.w lr @ CP#10 (VFP)
+ ret.w lr @ CP#11 (VFP)
#endif
- movw_pc lr @ CP#12
- movw_pc lr @ CP#13
- movw_pc lr @ CP#14 (Debug)
- movw_pc lr @ CP#15 (Control)
+ ret.w lr @ CP#12
+ ret.w lr @ CP#13
+ ret.w lr @ CP#14 (Debug)
+ ret.w lr @ CP#15 (Control)
#ifdef NEED_CPU_ARCHITECTURE
.align 2
@@ -649,7 +649,7 @@
.popsection
ENTRY(no_fp)
- mov pc, lr
+ ret lr
ENDPROC(no_fp)
__und_usr_fault_32:
@@ -745,7 +745,7 @@
#ifdef CONFIG_ARM_THUMB
bx \reg
#else
- mov pc, \reg
+ ret \reg
#endif
.endm
@@ -837,7 +837,7 @@
#if __LINUX_ARM_ARCH__ < 6
bcc kuser_cmpxchg32_fixup
#endif
- mov pc, lr
+ ret lr
.previous
#else
@@ -905,7 +905,7 @@
subs r8, r4, r7
rsbcss r8, r8, #(2b - 1b)
strcs r7, [sp, #S_PC]
- mov pc, lr
+ ret lr
.previous
#else
diff --git a/arch/arm/kernel/entry-common.S b/arch/arm/kernel/entry-common.S
index 7139d4a..e52fe5a 100644
--- a/arch/arm/kernel/entry-common.S
+++ b/arch/arm/kernel/entry-common.S
@@ -8,6 +8,7 @@
* published by the Free Software Foundation.
*/
+#include <asm/assembler.h>
#include <asm/unistd.h>
#include <asm/ftrace.h>
#include <asm/unwind.h>
@@ -88,7 +89,7 @@
cmp r5, #0
movne r0, r4
adrne lr, BSYM(1f)
- movne pc, r5
+ retne r5
1: get_thread_info tsk
b ret_slow_syscall
ENDPROC(ret_from_fork)
@@ -290,7 +291,7 @@
.macro mcount_exit
ldmia sp!, {r0-r3, ip, lr}
- mov pc, ip
+ ret ip
.endm
ENTRY(__gnu_mcount_nc)
@@ -298,7 +299,7 @@
#ifdef CONFIG_DYNAMIC_FTRACE
mov ip, lr
ldmia sp!, {lr}
- mov pc, ip
+ ret ip
#else
__mcount
#endif
@@ -333,12 +334,12 @@
bl ftrace_return_to_handler
mov lr, r0 @ r0 has real ret addr
ldmia sp!, {r0-r3}
- mov pc, lr
+ ret lr
#endif
ENTRY(ftrace_stub)
.Lftrace_stub:
- mov pc, lr
+ ret lr
ENDPROC(ftrace_stub)
#endif /* CONFIG_FUNCTION_TRACER */
@@ -561,7 +562,7 @@
streq r5, [sp, #4]
beq sys_mmap_pgoff
mov r0, #-EINVAL
- mov pc, lr
+ ret lr
#else
str r5, [sp, #4]
b sys_mmap_pgoff
diff --git a/arch/arm/kernel/entry-header.S b/arch/arm/kernel/entry-header.S
index 5d702f89..8db307d 100644
--- a/arch/arm/kernel/entry-header.S
+++ b/arch/arm/kernel/entry-header.S
@@ -240,12 +240,6 @@
movs pc, lr @ return & move spsr_svc into cpsr
.endm
- @
- @ 32-bit wide "mov pc, reg"
- @
- .macro movw_pc, reg
- mov pc, \reg
- .endm
#else /* CONFIG_THUMB2_KERNEL */
.macro svc_exit, rpsr, irq = 0
.if \irq != 0
@@ -304,14 +298,6 @@
movs pc, lr @ return & move spsr_svc into cpsr
.endm
#endif /* ifdef CONFIG_CPU_V7M / else */
-
- @
- @ 32-bit wide "mov pc, reg"
- @
- .macro movw_pc, reg
- mov pc, \reg
- nop
- .endm
#endif /* !CONFIG_THUMB2_KERNEL */
/*
diff --git a/arch/arm/kernel/fiqasm.S b/arch/arm/kernel/fiqasm.S
index 207f9d6..8dd26e1 100644
--- a/arch/arm/kernel/fiqasm.S
+++ b/arch/arm/kernel/fiqasm.S
@@ -32,7 +32,7 @@
ldr lr, [r0]
msr cpsr_c, r1 @ return to SVC mode
mov r0, r0 @ avoid hazard prior to ARMv4
- mov pc, lr
+ ret lr
ENDPROC(__set_fiq_regs)
ENTRY(__get_fiq_regs)
@@ -45,5 +45,5 @@
str lr, [r0]
msr cpsr_c, r1 @ return to SVC mode
mov r0, r0 @ avoid hazard prior to ARMv4
- mov pc, lr
+ ret lr
ENDPROC(__get_fiq_regs)
diff --git a/arch/arm/kernel/head-common.S b/arch/arm/kernel/head-common.S
index 572a383..8733012 100644
--- a/arch/arm/kernel/head-common.S
+++ b/arch/arm/kernel/head-common.S
@@ -10,6 +10,7 @@
* published by the Free Software Foundation.
*
*/
+#include <asm/assembler.h>
#define ATAG_CORE 0x54410001
#define ATAG_CORE_SIZE ((2*4 + 3*4) >> 2)
@@ -61,10 +62,10 @@
cmp r5, r6
bne 1f
-2: mov pc, lr @ atag/dtb pointer is ok
+2: ret lr @ atag/dtb pointer is ok
1: mov r2, #0
- mov pc, lr
+ ret lr
ENDPROC(__vet_atags)
/*
@@ -162,7 +163,7 @@
cmp r5, r6
blo 1b
mov r5, #0 @ unknown processor
-2: mov pc, lr
+2: ret lr
ENDPROC(__lookup_processor_type)
/*
diff --git a/arch/arm/kernel/head-nommu.S b/arch/arm/kernel/head-nommu.S
index 716249c..cc176b6 100644
--- a/arch/arm/kernel/head-nommu.S
+++ b/arch/arm/kernel/head-nommu.S
@@ -82,7 +82,7 @@
adr lr, BSYM(1f) @ return (PIC) address
ARM( add pc, r10, #PROCINFO_INITFUNC )
THUMB( add r12, r10, #PROCINFO_INITFUNC )
- THUMB( mov pc, r12 )
+ THUMB( ret r12 )
1: b __after_proc_init
ENDPROC(stext)
@@ -119,7 +119,7 @@
mov r13, r12 @ __secondary_switched address
ARM( add pc, r10, #PROCINFO_INITFUNC )
THUMB( add r12, r10, #PROCINFO_INITFUNC )
- THUMB( mov pc, r12 )
+ THUMB( ret r12 )
ENDPROC(secondary_startup)
ENTRY(__secondary_switched)
@@ -164,7 +164,7 @@
#endif
mcr p15, 0, r0, c1, c0, 0 @ write control reg
#endif /* CONFIG_CPU_CP15 */
- mov pc, r13
+ ret r13
ENDPROC(__after_proc_init)
.ltorg
@@ -254,7 +254,7 @@
orr r0, r0, #CR_M @ Set SCTRL.M (MPU on)
mcr p15, 0, r0, c1, c0, 0 @ Enable MPU
isb
- mov pc,lr
+ ret lr
ENDPROC(__setup_mpu)
#endif
#include "head-common.S"
diff --git a/arch/arm/kernel/head.S b/arch/arm/kernel/head.S
index 2c35f0f..664eee8 100644
--- a/arch/arm/kernel/head.S
+++ b/arch/arm/kernel/head.S
@@ -140,7 +140,7 @@
mov r8, r4 @ set TTBR1 to swapper_pg_dir
ARM( add pc, r10, #PROCINFO_INITFUNC )
THUMB( add r12, r10, #PROCINFO_INITFUNC )
- THUMB( mov pc, r12 )
+ THUMB( ret r12 )
1: b __enable_mmu
ENDPROC(stext)
.ltorg
@@ -335,7 +335,7 @@
sub r4, r4, #0x1000 @ point to the PGD table
mov r4, r4, lsr #ARCH_PGD_SHIFT
#endif
- mov pc, lr
+ ret lr
ENDPROC(__create_page_tables)
.ltorg
.align
@@ -383,7 +383,7 @@
ARM( add pc, r10, #PROCINFO_INITFUNC ) @ initialise processor
@ (return control reg)
THUMB( add r12, r10, #PROCINFO_INITFUNC )
- THUMB( mov pc, r12 )
+ THUMB( ret r12 )
ENDPROC(secondary_startup)
/*
@@ -468,7 +468,7 @@
instr_sync
mov r3, r3
mov r3, r13
- mov pc, r3
+ ret r3
__turn_mmu_on_end:
ENDPROC(__turn_mmu_on)
.popsection
@@ -487,7 +487,7 @@
orr r4, r4, #0x0000b000
orr r4, r4, #0x00000020 @ val 0x4100b020
teq r3, r4 @ ARM 11MPCore?
- moveq pc, lr @ yes, assume SMP
+ reteq lr @ yes, assume SMP
mrc p15, 0, r0, c0, c0, 5 @ read MPIDR
and r0, r0, #0xc0000000 @ multiprocessing extensions and
@@ -500,7 +500,7 @@
orr r4, r4, #0x0000c000
orr r4, r4, #0x00000090
teq r3, r4 @ Check for ARM Cortex-A9
- movne pc, lr @ Not ARM Cortex-A9,
+ retne lr @ Not ARM Cortex-A9,
@ If a future SoC *does* use 0x0 as the PERIPH_BASE, then the
@ below address check will need to be #ifdef'd or equivalent
@@ -512,7 +512,7 @@
ARM_BE8(rev r0, r0) @ byteswap if big endian
and r0, r0, #0x3 @ number of CPUs
teq r0, #0x0 @ is 1?
- movne pc, lr
+ retne lr
__fixup_smp_on_up:
adr r0, 1f
@@ -539,7 +539,7 @@
.text
__do_fixup_smp_on_up:
cmp r4, r5
- movhs pc, lr
+ reths lr
ldmia r4!, {r0, r6}
ARM( str r6, [r0, r3] )
THUMB( add r0, r0, r3 )
@@ -672,7 +672,7 @@
2: cmp r4, r5
ldrcc r7, [r4], #4 @ use branch for delay slot
bcc 1b
- mov pc, lr
+ ret lr
#endif
ENDPROC(__fixup_a_pv_table)
diff --git a/arch/arm/kernel/hyp-stub.S b/arch/arm/kernel/hyp-stub.S
index 797b1a6a..56ce6290 100644
--- a/arch/arm/kernel/hyp-stub.S
+++ b/arch/arm/kernel/hyp-stub.S
@@ -99,7 +99,7 @@
* immediately.
*/
compare_cpu_mode_with_primary r4, r5, r6, r7
- movne pc, lr
+ retne lr
/*
* Once we have given up on one CPU, we do not try to install the
@@ -111,7 +111,7 @@
*/
cmp r4, #HYP_MODE
- movne pc, lr @ give up if the CPU is not in HYP mode
+ retne lr @ give up if the CPU is not in HYP mode
/*
* Configure HSCTLR to set correct exception endianness/instruction set
@@ -201,7 +201,7 @@
@ fall through
ENTRY(__hyp_set_vectors)
__HVC(0)
- mov pc, lr
+ ret lr
ENDPROC(__hyp_set_vectors)
#ifndef ZIMAGE
diff --git a/arch/arm/kernel/iwmmxt.S b/arch/arm/kernel/iwmmxt.S
index a5599cf..0960be7 100644
--- a/arch/arm/kernel/iwmmxt.S
+++ b/arch/arm/kernel/iwmmxt.S
@@ -179,7 +179,7 @@
get_thread_info r10
#endif
4: dec_preempt_count r10, r3
- mov pc, lr
+ ret lr
/*
* Back up Concan regs to save area and disable access to them
@@ -265,7 +265,7 @@
mov r3, lr @ preserve return address
bl concan_dump
msr cpsr_c, ip @ restore interrupt mode
- mov pc, r3
+ ret r3
/*
* Restore Concan state from given memory address
@@ -301,7 +301,7 @@
mov r3, lr @ preserve return address
bl concan_load
msr cpsr_c, ip @ restore interrupt mode
- mov pc, r3
+ ret r3
/*
* Concan handling on task switch
@@ -323,7 +323,7 @@
add r3, r0, #TI_IWMMXT_STATE @ get next task Concan save area
ldr r2, [r2] @ get current Concan owner
teq r2, r3 @ next task owns it?
- movne pc, lr @ no: leave Concan disabled
+ retne lr @ no: leave Concan disabled
1: @ flip Concan access
XSC(eor r1, r1, #0x3)
@@ -350,7 +350,7 @@
eors r0, r0, r1 @ if equal...
streq r0, [r3] @ then clear ownership
msr cpsr_c, r2 @ restore interrupts
- mov pc, lr
+ ret lr
.data
concan_owner:
diff --git a/arch/arm/kernel/relocate_kernel.S b/arch/arm/kernel/relocate_kernel.S
index 9585896..35e7258 100644
--- a/arch/arm/kernel/relocate_kernel.S
+++ b/arch/arm/kernel/relocate_kernel.S
@@ -3,6 +3,7 @@
*/
#include <linux/linkage.h>
+#include <asm/assembler.h>
#include <asm/kexec.h>
.align 3 /* not needed for this code, but keeps fncpy() happy */
@@ -59,7 +60,7 @@
mov r0,#0
ldr r1,kexec_mach_type
ldr r2,kexec_boot_atags
- ARM( mov pc, lr )
+ ARM( ret lr )
THUMB( bx lr )
.align
diff --git a/arch/arm/kernel/sleep.S b/arch/arm/kernel/sleep.S
index 1b880db..e1e60e5 100644
--- a/arch/arm/kernel/sleep.S
+++ b/arch/arm/kernel/sleep.S
@@ -107,7 +107,7 @@
instr_sync
mov r0, r0
mov r0, r0
- mov pc, r3 @ jump to virtual address
+ ret r3 @ jump to virtual address
ENDPROC(cpu_resume_mmu)
.popsection
cpu_resume_after_mmu:
