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Linus Torvalds1da177e2005-04-16 15:20:36 -07001/*
2 * linux/arch/arm/lib/backtrace.S
3 *
4 * Copyright (C) 1995, 1996 Russell King
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 * 27/03/03 Ian Molton Clean up CONFIG_CPU
11 *
12 */
Linus Torvalds1da177e2005-04-16 15:20:36 -070013#include <linux/linkage.h>
14#include <asm/assembler.h>
15 .text
16
17@ fp is 0 or stack frame
18
19#define frame r4
Russell King7ab3f8d2007-03-02 15:01:36 +000020#define sv_fp r5
21#define sv_pc r6
Linus Torvalds1da177e2005-04-16 15:20:36 -070022#define mask r7
23#define offset r8
24
25ENTRY(__backtrace)
26 mov r1, #0x10
27 mov r0, fp
28
29ENTRY(c_backtrace)
30
Malcolm Parsons3ee357f2006-03-25 21:58:03 +000031#if !defined(CONFIG_FRAME_POINTER) || !defined(CONFIG_PRINTK)
Linus Torvalds1da177e2005-04-16 15:20:36 -070032 mov pc, lr
Catalin Marinas93ed3972008-08-28 11:22:32 +010033ENDPROC(__backtrace)
34ENDPROC(c_backtrace)
Linus Torvalds1da177e2005-04-16 15:20:36 -070035#else
Linus Torvalds1da177e2005-04-16 15:20:36 -070036 stmfd sp!, {r4 - r8, lr} @ Save an extra register so we have a location...
Russell King7ab3f8d2007-03-02 15:01:36 +000037 movs frame, r0 @ if frame pointer is zero
38 beq no_frame @ we have no stack frames
Linus Torvalds1da177e2005-04-16 15:20:36 -070039
Russell King7ab3f8d2007-03-02 15:01:36 +000040 tst r1, #0x10 @ 26 or 32-bit mode?
Catalin Marinas8b592782009-07-24 12:32:57 +010041 ARM( moveq mask, #0xfc000003 )
42 THUMB( moveq mask, #0xfc000000 )
43 THUMB( orreq mask, #0x03 )
Russell King7ab3f8d2007-03-02 15:01:36 +000044 movne mask, #0 @ mask for 32-bit
45
461: stmfd sp!, {pc} @ calculate offset of PC stored
47 ldr r0, [sp], #4 @ by stmfd for this CPU
48 adr r1, 1b
Linus Torvalds1da177e2005-04-16 15:20:36 -070049 sub offset, r0, r1
50
Russell King7ab3f8d2007-03-02 15:01:36 +000051/*
52 * Stack frame layout:
53 * optionally saved caller registers (r4 - r10)
54 * saved fp
55 * saved sp
56 * saved lr
57 * frame => saved pc
58 * optionally saved arguments (r0 - r3)
59 * saved sp => <next word>
60 *
61 * Functions start with the following code sequence:
62 * mov ip, sp
63 * stmfd sp!, {r0 - r3} (optional)
64 * corrected pc => stmfd sp!, {..., fp, ip, lr, pc}
65 */
66for_each_frame: tst frame, mask @ Check for address exceptions
67 bne no_frame
Linus Torvalds1da177e2005-04-16 15:20:36 -070068
Russell King7ab3f8d2007-03-02 15:01:36 +0000691001: ldr sv_pc, [frame, #0] @ get saved pc
701002: ldr sv_fp, [frame, #-12] @ get saved fp
71
72 sub sv_pc, sv_pc, offset @ Correct PC for prefetching
73 bic sv_pc, sv_pc, mask @ mask PC/LR for the mode
74
751003: ldr r2, [sv_pc, #-4] @ if stmfd sp!, {args} exists,
76 ldr r3, .Ldsi+4 @ adjust saved 'pc' back one
77 teq r3, r2, lsr #10 @ instruction
78 subne r0, sv_pc, #4 @ allow for mov
79 subeq r0, sv_pc, #8 @ allow for mov + stmia
80
81 ldr r1, [frame, #-4] @ get saved lr
82 mov r2, frame
83 bic r1, r1, mask @ mask PC/LR for the mode
Linus Torvalds1da177e2005-04-16 15:20:36 -070084 bl dump_backtrace_entry
85
Russell King7ab3f8d2007-03-02 15:01:36 +000086 ldr r1, [sv_pc, #-4] @ if stmfd sp!, {args} exists,
87 ldr r3, .Ldsi+4
88 teq r3, r1, lsr #10
89 ldreq r0, [frame, #-8] @ get sp
90 subeq r0, r0, #4 @ point at the last arg
91 bleq .Ldumpstm @ dump saved registers
Linus Torvalds1da177e2005-04-16 15:20:36 -070092
Russell King7ab3f8d2007-03-02 15:01:36 +0000931004: ldr r1, [sv_pc, #0] @ if stmfd sp!, {..., fp, ip, lr, pc}
94 ldr r3, .Ldsi @ instruction exists,
95 teq r3, r1, lsr #10
96 subeq r0, frame, #16
97 bleq .Ldumpstm @ dump saved registers
Linus Torvalds1da177e2005-04-16 15:20:36 -070098
Russell King7ab3f8d2007-03-02 15:01:36 +000099 teq sv_fp, #0 @ zero saved fp means
100 beq no_frame @ no further frames
Linus Torvalds1da177e2005-04-16 15:20:36 -0700101
Russell King7ab3f8d2007-03-02 15:01:36 +0000102 cmp sv_fp, frame @ next frame must be
103 mov frame, sv_fp @ above the current frame
104 bhi for_each_frame
Linus Torvalds1da177e2005-04-16 15:20:36 -0700105
Russell King7ab3f8d2007-03-02 15:01:36 +00001061006: adr r0, .Lbad
Linus Torvalds1da177e2005-04-16 15:20:36 -0700107 mov r1, frame
108 bl printk
Russell King7ab3f8d2007-03-02 15:01:36 +0000109no_frame: ldmfd sp!, {r4 - r8, pc}
Catalin Marinas93ed3972008-08-28 11:22:32 +0100110ENDPROC(__backtrace)
111ENDPROC(c_backtrace)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700112
Russell King42604152010-04-19 10:15:03 +0100113 .pushsection __ex_table,"a"
Linus Torvalds1da177e2005-04-16 15:20:36 -0700114 .align 3
Russell King7ab3f8d2007-03-02 15:01:36 +0000115 .long 1001b, 1006b
116 .long 1002b, 1006b
117 .long 1003b, 1006b
118 .long 1004b, 1006b
Russell King42604152010-04-19 10:15:03 +0100119 .popsection
Linus Torvalds1da177e2005-04-16 15:20:36 -0700120
121#define instr r4
122#define reg r5
123#define stack r6
124
Russell King7ab3f8d2007-03-02 15:01:36 +0000125.Ldumpstm: stmfd sp!, {instr, reg, stack, r7, lr}
Linus Torvalds1da177e2005-04-16 15:20:36 -0700126 mov stack, r0
127 mov instr, r1
Russell King7ab3f8d2007-03-02 15:01:36 +0000128 mov reg, #10
Linus Torvalds1da177e2005-04-16 15:20:36 -0700129 mov r7, #0
1301: mov r3, #1
Catalin Marinas8b592782009-07-24 12:32:57 +0100131 ARM( tst instr, r3, lsl reg )
132 THUMB( lsl r3, reg )
133 THUMB( tst instr, r3 )
Linus Torvalds1da177e2005-04-16 15:20:36 -0700134 beq 2f
135 add r7, r7, #1
Russell King7ab3f8d2007-03-02 15:01:36 +0000136 teq r7, #6
137 moveq r7, #1
138 moveq r1, #'\n'
139 movne r1, #' '
140 ldr r3, [stack], #-4
141 mov r2, reg
Linus Torvalds1da177e2005-04-16 15:20:36 -0700142 adr r0, .Lfp
143 bl printk
1442: subs reg, reg, #1
145 bpl 1b
146 teq r7, #0
147 adrne r0, .Lcr
148 blne printk
Russell King7ab3f8d2007-03-02 15:01:36 +0000149 ldmfd sp!, {instr, reg, stack, r7, pc}
Linus Torvalds1da177e2005-04-16 15:20:36 -0700150
Russell King7ab3f8d2007-03-02 15:01:36 +0000151.Lfp: .asciz "%cr%d:%08x"
Linus Torvalds1da177e2005-04-16 15:20:36 -0700152.Lcr: .asciz "\n"
153.Lbad: .asciz "Backtrace aborted due to bad frame pointer <%p>\n"
154 .align
Russell King7ab3f8d2007-03-02 15:01:36 +0000155.Ldsi: .word 0xe92dd800 >> 10 @ stmfd sp!, {... fp, ip, lr, pc}
156 .word 0xe92d0000 >> 10 @ stmfd sp!, {}
Linus Torvalds1da177e2005-04-16 15:20:36 -0700157
158#endif