xref: /openbmc/linux/arch/arm/kernel/entry-v7m.S (revision 3d40aed8) 
1/* SPDX-License-Identifier: GPL-2.0-only */
2/*
3 * linux/arch/arm/kernel/entry-v7m.S
4 *
5 * Copyright (C) 2008 ARM Ltd.
6 *
7 * Low-level vector interface routines for the ARMv7-M architecture
8 */
9#include <asm/page.h>
10#include <asm/glue.h>
11#include <asm/thread_notify.h>
12#include <asm/v7m.h>
13
14#include "entry-header.S"
15
16#ifdef CONFIG_TRACE_IRQFLAGS
17#error "CONFIG_TRACE_IRQFLAGS not supported on the current ARMv7M implementation"
18#endif
19
20__invalid_entry:
21	v7m_exception_entry
22#ifdef CONFIG_PRINTK
23	adr	r0, strerr
24	mrs	r1, ipsr
25	mov	r2, lr
26	bl	_printk
27#endif
28	mov	r0, sp
29	bl	show_regs
301:	b	1b
31ENDPROC(__invalid_entry)
32
33strerr:	.asciz	"\nUnhandled exception: IPSR = %08lx LR = %08lx\n"
34
35	.align	2
36__irq_entry:
37	v7m_exception_entry
38
39	@
40	@ Invoke the IRQ handler
41	@
42	mov	r0, sp
43	ldr_this_cpu sp, irq_stack_ptr, r1, r2
44
45	@
46	@ If we took the interrupt while running in the kernel, we may already
47	@ be using the IRQ stack, so revert to the original value in that case.
48	@
49	subs	r2, sp, r0		@ SP above bottom of IRQ stack?
50	rsbscs	r2, r2, #THREAD_SIZE	@ ... and below the top?
51	movcs	sp, r0
52
53	push	{r0, lr}		@ preserve LR and original SP
54
55	@ routine called with r0 = struct pt_regs *
56	bl	generic_handle_arch_irq
57
58	pop	{r0, lr}
59	mov	sp, r0
60
61	@
62	@ Check for any pending work if returning to user
63	@
64	ldr	r1, =BASEADDR_V7M_SCB
65	ldr	r0, [r1, V7M_SCB_ICSR]
66	tst	r0, V7M_SCB_ICSR_RETTOBASE
67	beq	2f
68
69	get_thread_info tsk
70	ldr	r2, [tsk, #TI_FLAGS]
71	movs	r2, r2, lsl #16
72	beq	2f			@ no work pending
73	mov	r0, #V7M_SCB_ICSR_PENDSVSET
74	str	r0, [r1, V7M_SCB_ICSR]	@ raise PendSV
75
762:
77	@ registers r0-r3 and r12 are automatically restored on exception
78	@ return. r4-r7 were not clobbered in v7m_exception_entry so for
79	@ correctness they don't need to be restored. So only r8-r11 must be
80	@ restored here. The easiest way to do so is to restore r0-r7, too.
81	ldmia	sp!, {r0-r11}
82	add	sp, #PT_REGS_SIZE-S_IP
83	cpsie	i
84	bx	lr
85ENDPROC(__irq_entry)
86
87__pendsv_entry:
88	v7m_exception_entry
89
90	ldr	r1, =BASEADDR_V7M_SCB
91	mov	r0, #V7M_SCB_ICSR_PENDSVCLR
92	str	r0, [r1, V7M_SCB_ICSR]	@ clear PendSV
93
94	@ execute the pending work, including reschedule
95	get_thread_info tsk
96	mov	why, #0
97	b	ret_to_user_from_irq
98ENDPROC(__pendsv_entry)
99
100/*
101 * Register switch for ARMv7-M processors.
102 * r0 = previous task_struct, r1 = previous thread_info, r2 = next thread_info
103 * previous and next are guaranteed not to be the same.
104 */
105ENTRY(__switch_to)
106	.fnstart
107	.cantunwind
108	add	ip, r1, #TI_CPU_SAVE
109	stmia	ip!, {r4 - r11}		@ Store most regs on stack
110	str	sp, [ip], #4
111	str	lr, [ip], #4
112	mov	r5, r0
113	mov	r6, r2			@ Preserve 'next'
114	add	r4, r2, #TI_CPU_SAVE
115	ldr	r0, =thread_notify_head
116	mov	r1, #THREAD_NOTIFY_SWITCH
117	bl	atomic_notifier_call_chain
118	mov	r0, r5
119	mov	r1, r6
120	ldmia	r4, {r4 - r12, lr}	@ Load all regs saved previously
121	set_current r1, r2
122	mov	sp, ip
123	bx	lr
124	.fnend
125ENDPROC(__switch_to)
126
127	.data
128#if CONFIG_CPU_V7M_NUM_IRQ <= 112
129	.align	9
130#else
131	.align	10
132#endif
133
134/*
135 * Vector table (Natural alignment need to be ensured)
136 */
137ENTRY(vector_table)
138	.long	0			@ 0 - Reset stack pointer
139	.long	__invalid_entry		@ 1 - Reset
140	.long	__invalid_entry		@ 2 - NMI
141	.long	__invalid_entry		@ 3 - HardFault
142	.long	__invalid_entry		@ 4 - MemManage
143	.long	__invalid_entry		@ 5 - BusFault
144	.long	__invalid_entry		@ 6 - UsageFault
145	.long	__invalid_entry		@ 7 - Reserved
146	.long	__invalid_entry		@ 8 - Reserved
147	.long	__invalid_entry		@ 9 - Reserved
148	.long	__invalid_entry		@ 10 - Reserved
149	.long	vector_swi		@ 11 - SVCall
150	.long	__invalid_entry		@ 12 - Debug Monitor
151	.long	__invalid_entry		@ 13 - Reserved
152	.long	__pendsv_entry		@ 14 - PendSV
153	.long	__invalid_entry		@ 15 - SysTick
154	.rept	CONFIG_CPU_V7M_NUM_IRQ
155	.long	__irq_entry		@ External Interrupts
156	.endr
157	.align	2
158	.globl	exc_ret
159exc_ret:
160	.space	4
161