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torvalds
GitHub Repository: torvalds/linux
 Path: blob/master/arch/arm/kernel/entry-v7m.S
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/* SPDX-License-Identifier: GPL-2.0-only */

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/*

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 * linux/arch/arm/kernel/entry-v7m.S

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 *

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 * Copyright (C) 2008 ARM Ltd.

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 *

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 * Low-level vector interface routines for the ARMv7-M architecture

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 */

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#include <asm/page.h>

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#include <asm/glue.h>

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#include <asm/thread_notify.h>

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#include <asm/v7m.h>

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#include "entry-header.S"

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#ifdef CONFIG_TRACE_IRQFLAGS

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#error "CONFIG_TRACE_IRQFLAGS not supported on the current ARMv7M implementation"

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#endif

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__invalid_entry:

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	v7m_exception_entry

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#ifdef CONFIG_PRINTK

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	adr	r0, strerr

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	mrs	r1, ipsr

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	mov	r2, lr

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	bl	_printk

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#endif

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	mov	r0, sp

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	bl	show_regs

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1:	b	1b

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ENDPROC(__invalid_entry)

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strerr:	.asciz	"\nUnhandled exception: IPSR = %08lx LR = %08lx\n"

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	.align	2

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__irq_entry:

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	v7m_exception_entry

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	@

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	@ Invoke the IRQ handler

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	@

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	mov	r0, sp

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	ldr_this_cpu sp, irq_stack_ptr, r1, r2

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	@

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	@ If we took the interrupt while running in the kernel, we may already

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	@ be using the IRQ stack, so revert to the original value in that case.

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	@

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	subs	r2, sp, r0		@ SP above bottom of IRQ stack?

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	rsbscs	r2, r2, #THREAD_SIZE	@ ... and below the top?

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	movcs	sp, r0

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	push	{r0, lr}		@ preserve LR and original SP

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	@ routine called with r0 = struct pt_regs *

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	bl	generic_handle_arch_irq

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	pop	{r0, lr}

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	mov	sp, r0

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	@

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	@ Check for any pending work if returning to user

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	@

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	ldr	r1, =BASEADDR_V7M_SCB

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	ldr	r0, [r1, V7M_SCB_ICSR]

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	tst	r0, V7M_SCB_ICSR_RETTOBASE

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	beq	2f

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	get_thread_info tsk

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	ldr	r2, [tsk, #TI_FLAGS]

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	movs	r2, r2, lsl #16

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	beq	2f			@ no work pending

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	mov	r0, #V7M_SCB_ICSR_PENDSVSET

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	str	r0, [r1, V7M_SCB_ICSR]	@ raise PendSV

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2:

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	@ registers r0-r3 and r12 are automatically restored on exception

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	@ return. r4-r7 were not clobbered in v7m_exception_entry so for

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	@ correctness they don't need to be restored. So only r8-r11 must be

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	@ restored here. The easiest way to do so is to restore r0-r7, too.

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	ldmia	sp!, {r0-r11}

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	add	sp, #PT_REGS_SIZE-S_IP

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	cpsie	i

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	bx	lr

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ENDPROC(__irq_entry)

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__pendsv_entry:

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	v7m_exception_entry

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	ldr	r1, =BASEADDR_V7M_SCB

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	mov	r0, #V7M_SCB_ICSR_PENDSVCLR

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	str	r0, [r1, V7M_SCB_ICSR]	@ clear PendSV

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	@ execute the pending work, including reschedule

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	get_thread_info tsk

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	mov	why, #0

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	b	ret_to_user_from_irq

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ENDPROC(__pendsv_entry)

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/*

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 * Register switch for ARMv7-M processors.

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 * r0 = previous task_struct, r1 = previous thread_info, r2 = next thread_info

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 * previous and next are guaranteed not to be the same.

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 */

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ENTRY(__switch_to)

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	.fnstart

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	.cantunwind

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	add	ip, r1, #TI_CPU_SAVE

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	stmia	ip!, {r4 - r11}		@ Store most regs on stack

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	str	sp, [ip], #4

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	str	lr, [ip], #4

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	mov	r5, r0

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	mov	r6, r2			@ Preserve 'next'

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	add	r4, r2, #TI_CPU_SAVE

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	ldr	r0, =thread_notify_head

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	mov	r1, #THREAD_NOTIFY_SWITCH

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	bl	atomic_notifier_call_chain

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	mov	r0, r5

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	mov	r1, r6

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	ldmia	r4, {r4 - r12, lr}	@ Load all regs saved previously

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	set_current r1, r2

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	mov	sp, ip

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	bx	lr

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	.fnend

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ENDPROC(__switch_to)

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	.data

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#if CONFIG_CPU_V7M_NUM_IRQ <= 112

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	.align	9

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#else

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	.align	10

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#endif

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/*

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 * Vector table (Natural alignment need to be ensured)

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 */

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ENTRY(vector_table)

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	.long	0			@ 0 - Reset stack pointer

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	.long	__invalid_entry		@ 1 - Reset

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	.long	__invalid_entry		@ 2 - NMI

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	.long	__invalid_entry		@ 3 - HardFault

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	.long	__invalid_entry		@ 4 - MemManage

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	.long	__invalid_entry		@ 5 - BusFault

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	.long	__invalid_entry		@ 6 - UsageFault

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	.long	__invalid_entry		@ 7 - Reserved

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	.long	__invalid_entry		@ 8 - Reserved

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	.long	__invalid_entry		@ 9 - Reserved

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	.long	__invalid_entry		@ 10 - Reserved

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	.long	vector_swi		@ 11 - SVCall

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	.long	__invalid_entry		@ 12 - Debug Monitor

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	.long	__invalid_entry		@ 13 - Reserved

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	.long	__pendsv_entry		@ 14 - PendSV

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	.long	__invalid_entry		@ 15 - SysTick

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	.rept	CONFIG_CPU_V7M_NUM_IRQ

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	.long	__irq_entry		@ External Interrupts

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	.endr

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	.align	2

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	.globl	exc_ret

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exc_ret:

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	.space	4

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