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
30 1: b 1b
31 ENDPROC(__invalid_entry)
32
33 strerr: .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
76 2:
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
85 ENDPROC(__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
98 ENDPROC(__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 */
105 ENTRY(__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
125 ENDPROC(__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 */
137 ENTRY(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
159 exc_ret:
160 .space 4
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