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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 | |
| parent | af040ffc9ba1e079ee4c0748aff64fa3d4716fa5 (diff) | |
| download | linux-6ebbf2ce437b33022d30badd49dc94d33ecfa498.tar.gz linux-6ebbf2ce437b33022d30badd49dc94d33ecfa498.tar.bz2 linux-6ebbf2ce437b33022d30badd49dc94d33ecfa498.zip | |
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>
106 files changed, 644 insertions, 607 deletions
diff --git a/arch/arm/crypto/aes-armv4.S b/arch/arm/crypto/aes-armv4.S index 3a14ea8fe97e..ebb9761fb572 100644 --- a/arch/arm/crypto/aes-armv4.S +++ b/arch/arm/crypto/aes-armv4.S @@ -35,6 +35,7 @@ @ that is being targetted. #include <linux/linkage.h> +#include <asm/assembler.h> .text @@ -648,7 +649,7 @@ _armv4_AES_set_encrypt_key: .Ldone: mov r0,#0 ldmia sp!,{r4-r12,lr} -.Labrt: mov pc,lr +.Labrt: ret lr ENDPROC(private_AES_set_encrypt_key) .align 5 diff --git a/arch/arm/include/asm/assembler.h b/arch/arm/include/asm/assembler.h index 906703a5b564..f67fd3afebdf 100644 --- a/arch/arm/include/asm/assembler.h +++ b/arch/arm/include/asm/assembler.h @@ -427,4 +427,25 @@ THUMB( orr \reg , \reg , #PSR_T_BIT ) #endif .endm + .irp c,,eq,ne,cs,cc,mi,pl,vs,vc,hi,ls,ge,lt,gt,le,hs,lo + .macro ret\c, reg +#if __LINUX_ARM_ARCH__ < 6 + mov\c pc, \reg +#else + .ifeqs "\reg", "lr" + bx\c \reg + .else + mov\c pc, \reg + .endif +#endif + .endm + .endr + + .macro ret.w, reg + ret \reg +#ifdef CONFIG_THUMB2_KERNEL + nop +#endif + .endm + #endif /* __ASM_ASSEMBLER_H__ */ diff --git a/arch/arm/include/asm/entry-macro-multi.S b/arch/arm/include/asm/entry-macro-multi.S index 88d61815f0c0..469a2b30fa27 100644 --- a/arch/arm/include/asm/entry-macro-multi.S +++ b/arch/arm/include/asm/entry-macro-multi.S @@ -35,5 +35,5 @@ \symbol_name: mov r8, lr arch_irq_handler_default - mov pc, r8 + ret r8 .endm diff --git a/arch/arm/kernel/debug.S b/arch/arm/kernel/debug.S index 14f7c3b14632..78c91b5f97d4 100644 --- a/arch/arm/kernel/debug.S +++ b/arch/arm/kernel/debug.S @@ -90,7 +90,7 @@ ENTRY(printascii) ldrneb r1, [r0], #1 teqne r1, #0 bne 1b - mov pc, lr + ret lr ENDPROC(printascii) ENTRY(printch) @@ -105,7 +105,7 @@ ENTRY(debug_ll_addr) addruart r2, r3, ip str r2, [r0] str r3, [r1] - mov pc, lr + ret lr ENDPROC(debug_ll_addr) #endif @@ -116,7 +116,7 @@ ENTRY(printascii) mov r0, #0x04 @ SYS_WRITE0 ARM( svc #0x123456 ) THUMB( svc #0xab ) - mov pc, lr + ret lr ENDPROC(printascii) ENTRY(printch) @@ -125,14 +125,14 @@ ENTRY(printch) 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 52a949a8077d..36276cdccfbc 100644 --- a/arch/arm/kernel/entry-armv.S +++ b/arch/arm/kernel/entry-armv.S @@ -224,7 +224,7 @@ svc_preempt: 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 @@ ENDPROC(__und_usr) .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 @@ call_fpe: #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 @@ call_fpe: 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 @@ ENTRY(fp_enter) .popsection ENTRY(no_fp) - mov pc, lr + ret lr ENDPROC(no_fp) __und_usr_fault_32: @@ -745,7 +745,7 @@ ENDPROC(__switch_to) #ifdef CONFIG_ARM_THUMB bx \reg #else - mov pc, \reg + ret \reg #endif .endm @@ -837,7 +837,7 @@ kuser_cmpxchg64_fixup: #if __LINUX_ARM_ARCH__ < 6 bcc kuser_cmpxchg32_fixup #endif - mov pc, lr + ret lr .previous #else @@ -905,7 +905,7 @@ kuser_cmpxchg32_fixup: 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 7139d4a7dea7..e52fe5a2d843 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 @@ ENTRY(ret_from_fork) 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 @@ ENDPROC(ftrace_graph_caller_old) .macro mcount_exit ldmia sp!, {r0-r3, ip, lr} - mov pc, ip + ret ip .endm ENTRY(__gnu_mcount_nc) @@ -298,7 +299,7 @@ UNWIND(.fnstart) #ifdef CONFIG_DYNAMIC_FTRACE mov ip, lr ldmia sp!, {lr} - mov pc, ip + ret ip #else __mcount #endif @@ -333,12 +334,12 @@ return_to_handler: 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) .Lftra |