xref: /openbmc/linux/arch/arm/kernel/entry-v7m.S (revision e8f6f3b4) 
1/*
2 * linux/arch/arm/kernel/entry-v7m.S
3 *
4 * Copyright (C) 2008 ARM Ltd.
5 *
6 * This program is free software; you can redistribute it and/or modify
7 * it under the terms of the GNU General Public License version 2 as
8 * published by the Free Software Foundation.
9 *
10 * Low-level vector interface routines for the ARMv7-M architecture
11 */
12#include <asm/memory.h>
13#include <asm/glue.h>
14#include <asm/thread_notify.h>
15#include <asm/v7m.h>
16
17#include "entry-header.S"
18
19#ifdef CONFIG_TRACE_IRQFLAGS
20#error "CONFIG_TRACE_IRQFLAGS not supported on the current ARMv7M implementation"
21#endif
22
23__invalid_entry:
24	v7m_exception_entry
25	adr	r0, strerr
26	mrs	r1, ipsr
27	mov	r2, lr
28	bl	printk
29	mov	r0, sp
30	bl	show_regs
311:	b	1b
32ENDPROC(__invalid_entry)
33
34strerr:	.asciz	"\nUnhandled exception: IPSR = %08lx LR = %08lx\n"
35
36	.align	2
37__irq_entry:
38	v7m_exception_entry
39
40	@
41	@ Invoke the IRQ handler
42	@
43	mrs	r0, ipsr
44	ldr	r1, =V7M_xPSR_EXCEPTIONNO
45	and	r0, r1
46	sub	r0, #16
47	mov	r1, sp
48	stmdb	sp!, {lr}
49	@ routine called with r0 = irq number, r1 = struct pt_regs *
50	bl	nvic_handle_irq
51
52	pop	{lr}
53	@
54	@ Check for any pending work if returning to user
55	@
56	ldr	r1, =BASEADDR_V7M_SCB
57	ldr	r0, [r1, V7M_SCB_ICSR]
58	tst	r0, V7M_SCB_ICSR_RETTOBASE
59	beq	2f
60
61	get_thread_info tsk
62	ldr	r2, [tsk, #TI_FLAGS]
63	tst	r2, #_TIF_WORK_MASK
64	beq	2f			@ no work pending
65	mov	r0, #V7M_SCB_ICSR_PENDSVSET
66	str	r0, [r1, V7M_SCB_ICSR]	@ raise PendSV
67
682:
69	@ registers r0-r3 and r12 are automatically restored on exception
70	@ return. r4-r7 were not clobbered in v7m_exception_entry so for
71	@ correctness they don't need to be restored. So only r8-r11 must be
72	@ restored here. The easiest way to do so is to restore r0-r7, too.
73	ldmia	sp!, {r0-r11}
74	add	sp, #S_FRAME_SIZE-S_IP
75	cpsie	i
76	bx	lr
77ENDPROC(__irq_entry)
78
79__pendsv_entry:
80	v7m_exception_entry
81
82	ldr	r1, =BASEADDR_V7M_SCB
83	mov	r0, #V7M_SCB_ICSR_PENDSVCLR
84	str	r0, [r1, V7M_SCB_ICSR]	@ clear PendSV
85
86	@ execute the pending work, including reschedule
87	get_thread_info tsk
88	mov	why, #0
89	b	ret_to_user
90ENDPROC(__pendsv_entry)
91
92/*
93 * Register switch for ARMv7-M processors.
94 * r0 = previous task_struct, r1 = previous thread_info, r2 = next thread_info
95 * previous and next are guaranteed not to be the same.
96 */
97ENTRY(__switch_to)
98	.fnstart
99	.cantunwind
100	add	ip, r1, #TI_CPU_SAVE
101	stmia	ip!, {r4 - r11}		@ Store most regs on stack
102	str	sp, [ip], #4
103	str	lr, [ip], #4
104	mov	r5, r0
105	add	r4, r2, #TI_CPU_SAVE
106	ldr	r0, =thread_notify_head
107	mov	r1, #THREAD_NOTIFY_SWITCH
108	bl	atomic_notifier_call_chain
109	mov	ip, r4
110	mov	r0, r5
111	ldmia	ip!, {r4 - r11}		@ Load all regs saved previously
112	ldr	sp, [ip]
113	ldr	pc, [ip, #4]!
114	.fnend
115ENDPROC(__switch_to)
116
117	.data
118	.align	8
119/*
120 * Vector table (64 words => 256 bytes natural alignment)
121 */
122ENTRY(vector_table)
123	.long	0			@ 0 - Reset stack pointer
124	.long	__invalid_entry		@ 1 - Reset
125	.long	__invalid_entry		@ 2 - NMI
126	.long	__invalid_entry		@ 3 - HardFault
127	.long	__invalid_entry		@ 4 - MemManage
128	.long	__invalid_entry		@ 5 - BusFault
129	.long	__invalid_entry		@ 6 - UsageFault
130	.long	__invalid_entry		@ 7 - Reserved
131	.long	__invalid_entry		@ 8 - Reserved
132	.long	__invalid_entry		@ 9 - Reserved
133	.long	__invalid_entry		@ 10 - Reserved
134	.long	vector_swi		@ 11 - SVCall
135	.long	__invalid_entry		@ 12 - Debug Monitor
136	.long	__invalid_entry		@ 13 - Reserved
137	.long	__pendsv_entry		@ 14 - PendSV
138	.long	__invalid_entry		@ 15 - SysTick
139	.rept	64 - 16
140	.long	__irq_entry		@ 16..64 - External Interrupts
141	.endr
142