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6ebbf2ce43
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>
159 lines
3.8 KiB
ArmAsm
159 lines
3.8 KiB
ArmAsm
/*
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* linux/arch/arm/mm/proc-v7m.S
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*
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* Copyright (C) 2008 ARM Ltd.
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* Copyright (C) 2001 Deep Blue Solutions Ltd.
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2 as
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* published by the Free Software Foundation.
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*
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* This is the "shell" of the ARMv7-M processor support.
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*/
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#include <linux/linkage.h>
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#include <asm/assembler.h>
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#include <asm/v7m.h>
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#include "proc-macros.S"
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ENTRY(cpu_v7m_proc_init)
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ret lr
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ENDPROC(cpu_v7m_proc_init)
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ENTRY(cpu_v7m_proc_fin)
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ret lr
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ENDPROC(cpu_v7m_proc_fin)
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/*
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* cpu_v7m_reset(loc)
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*
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* Perform a soft reset of the system. Put the CPU into the
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* same state as it would be if it had been reset, and branch
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* to what would be the reset vector.
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*
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* - loc - location to jump to for soft reset
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*/
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.align 5
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ENTRY(cpu_v7m_reset)
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ret r0
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ENDPROC(cpu_v7m_reset)
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/*
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* cpu_v7m_do_idle()
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*
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* Idle the processor (eg, wait for interrupt).
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*
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* IRQs are already disabled.
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*/
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ENTRY(cpu_v7m_do_idle)
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wfi
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ret lr
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ENDPROC(cpu_v7m_do_idle)
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ENTRY(cpu_v7m_dcache_clean_area)
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ret lr
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ENDPROC(cpu_v7m_dcache_clean_area)
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/*
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* There is no MMU, so here is nothing to do.
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*/
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ENTRY(cpu_v7m_switch_mm)
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ret lr
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ENDPROC(cpu_v7m_switch_mm)
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.globl cpu_v7m_suspend_size
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.equ cpu_v7m_suspend_size, 0
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#ifdef CONFIG_ARM_CPU_SUSPEND
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ENTRY(cpu_v7m_do_suspend)
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ret lr
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ENDPROC(cpu_v7m_do_suspend)
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ENTRY(cpu_v7m_do_resume)
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ret lr
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ENDPROC(cpu_v7m_do_resume)
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#endif
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.section ".text.init", #alloc, #execinstr
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/*
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* __v7m_setup
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*
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* This should be able to cover all ARMv7-M cores.
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*/
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__v7m_setup:
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@ Configure the vector table base address
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ldr r0, =BASEADDR_V7M_SCB
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ldr r12, =vector_table
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str r12, [r0, V7M_SCB_VTOR]
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@ enable UsageFault, BusFault and MemManage fault.
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ldr r5, [r0, #V7M_SCB_SHCSR]
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orr r5, #(V7M_SCB_SHCSR_USGFAULTENA | V7M_SCB_SHCSR_BUSFAULTENA | V7M_SCB_SHCSR_MEMFAULTENA)
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str r5, [r0, #V7M_SCB_SHCSR]
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@ Lower the priority of the SVC and PendSV exceptions
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mov r5, #0x80000000
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str r5, [r0, V7M_SCB_SHPR2] @ set SVC priority
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mov r5, #0x00800000
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str r5, [r0, V7M_SCB_SHPR3] @ set PendSV priority
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@ SVC to run the kernel in this mode
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adr r1, BSYM(1f)
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ldr r5, [r12, #11 * 4] @ read the SVC vector entry
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str r1, [r12, #11 * 4] @ write the temporary SVC vector entry
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mov r6, lr @ save LR
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mov r7, sp @ save SP
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ldr sp, =__v7m_setup_stack_top
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cpsie i
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svc #0
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1: cpsid i
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str r5, [r12, #11 * 4] @ restore the original SVC vector entry
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mov lr, r6 @ restore LR
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mov sp, r7 @ restore SP
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@ Special-purpose control register
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mov r1, #1
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msr control, r1 @ Thread mode has unpriviledged access
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@ Configure the System Control Register to ensure 8-byte stack alignment
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@ Note the STKALIGN bit is either RW or RAO.
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ldr r12, [r0, V7M_SCB_CCR] @ system control register
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orr r12, #V7M_SCB_CCR_STKALIGN
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str r12, [r0, V7M_SCB_CCR]
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ret lr
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ENDPROC(__v7m_setup)
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.align 2
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__v7m_setup_stack:
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.space 4 * 8 @ 8 registers
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__v7m_setup_stack_top:
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define_processor_functions v7m, dabort=nommu_early_abort, pabort=legacy_pabort, nommu=1
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.section ".rodata"
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string cpu_arch_name, "armv7m"
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string cpu_elf_name "v7m"
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string cpu_v7m_name "ARMv7-M"
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.section ".proc.info.init", #alloc, #execinstr
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/*
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* Match any ARMv7-M processor core.
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*/
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.type __v7m_proc_info, #object
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__v7m_proc_info:
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.long 0x000f0000 @ Required ID value
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.long 0x000f0000 @ Mask for ID
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.long 0 @ proc_info_list.__cpu_mm_mmu_flags
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.long 0 @ proc_info_list.__cpu_io_mmu_flags
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b __v7m_setup @ proc_info_list.__cpu_flush
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.long cpu_arch_name
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.long cpu_elf_name
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.long HWCAP_HALF|HWCAP_THUMB|HWCAP_FAST_MULT
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.long cpu_v7m_name
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.long v7m_processor_functions @ proc_info_list.proc
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.long 0 @ proc_info_list.tlb
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.long 0 @ proc_info_list.user
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.long nop_cache_fns @ proc_info_list.cache
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.size __v7m_proc_info, . - __v7m_proc_info
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