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1 | /* |
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 | */ | |
1da177e4 LT |
13 | #include <linux/linkage.h> |
14 | #include <asm/assembler.h> | |
15 | .text | |
16 | ||
17 | @ fp is 0 or stack frame | |
18 | ||
19 | #define frame r4 | |
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20 | #define sv_fp r5 |
21 | #define sv_pc r6 | |
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22 | #define mask r7 |
23 | #define offset r8 | |
24 | ||
25 | ENTRY(__backtrace) | |
26 | mov r1, #0x10 | |
27 | mov r0, fp | |
28 | ||
29 | ENTRY(c_backtrace) | |
30 | ||
3ee357f0 | 31 | #if !defined(CONFIG_FRAME_POINTER) || !defined(CONFIG_PRINTK) |
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32 | mov pc, lr |
33 | #else | |
1da177e4 | 34 | stmfd sp!, {r4 - r8, lr} @ Save an extra register so we have a location... |
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35 | movs frame, r0 @ if frame pointer is zero |
36 | beq no_frame @ we have no stack frames | |
37 | ||
38 | tst r1, #0x10 @ 26 or 32-bit mode? | |
39 | moveq mask, #0xfc000003 @ mask for 26-bit | |
40 | movne mask, #0 @ mask for 32-bit | |
41 | ||
42 | 1: stmfd sp!, {pc} @ calculate offset of PC stored | |
43 | ldr r0, [sp], #4 @ by stmfd for this CPU | |
44 | adr r1, 1b | |
1da177e4 LT |
45 | sub offset, r0, r1 |
46 | ||
7ab3f8d5 RK |
47 | /* |
48 | * Stack frame layout: | |
49 | * optionally saved caller registers (r4 - r10) | |
50 | * saved fp | |
51 | * saved sp | |
52 | * saved lr | |
53 | * frame => saved pc | |
54 | * optionally saved arguments (r0 - r3) | |
55 | * saved sp => <next word> | |
56 | * | |
57 | * Functions start with the following code sequence: | |
58 | * mov ip, sp | |
59 | * stmfd sp!, {r0 - r3} (optional) | |
60 | * corrected pc => stmfd sp!, {..., fp, ip, lr, pc} | |
61 | */ | |
62 | for_each_frame: tst frame, mask @ Check for address exceptions | |
63 | bne no_frame | |
64 | ||
65 | 1001: ldr sv_pc, [frame, #0] @ get saved pc | |
66 | 1002: ldr sv_fp, [frame, #-12] @ get saved fp | |
1da177e4 | 67 | |
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68 | sub sv_pc, sv_pc, offset @ Correct PC for prefetching |
69 | bic sv_pc, sv_pc, mask @ mask PC/LR for the mode | |
70 | ||
71 | 1003: ldr r2, [sv_pc, #-4] @ if stmfd sp!, {args} exists, | |
72 | ldr r3, .Ldsi+4 @ adjust saved 'pc' back one | |
73 | teq r3, r2, lsr #10 @ instruction | |
74 | subne r0, sv_pc, #4 @ allow for mov | |
75 | subeq r0, sv_pc, #8 @ allow for mov + stmia | |
76 | ||
77 | ldr r1, [frame, #-4] @ get saved lr | |
78 | mov r2, frame | |
79 | bic r1, r1, mask @ mask PC/LR for the mode | |
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80 | bl dump_backtrace_entry |
81 | ||
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82 | ldr r1, [sv_pc, #-4] @ if stmfd sp!, {args} exists, |
83 | ldr r3, .Ldsi+4 | |
84 | teq r3, r1, lsr #10 | |
85 | ldreq r0, [frame, #-8] @ get sp | |
86 | subeq r0, r0, #4 @ point at the last arg | |
87 | bleq .Ldumpstm @ dump saved registers | |
1da177e4 | 88 | |
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89 | 1004: ldr r1, [sv_pc, #0] @ if stmfd sp!, {..., fp, ip, lr, pc} |
90 | ldr r3, .Ldsi @ instruction exists, | |
91 | teq r3, r1, lsr #10 | |
92 | subeq r0, frame, #16 | |
93 | bleq .Ldumpstm @ dump saved registers | |
94 | ||
95 | teq sv_fp, #0 @ zero saved fp means | |
96 | beq no_frame @ no further frames | |
97 | ||
98 | cmp sv_fp, frame @ next frame must be | |
99 | mov frame, sv_fp @ above the current frame | |
100 | bhi for_each_frame | |
101 | ||
102 | 1006: adr r0, .Lbad | |
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103 | mov r1, frame |
104 | bl printk | |
7ab3f8d5 | 105 | no_frame: ldmfd sp!, {r4 - r8, pc} |
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106 | |
107 | .section __ex_table,"a" | |
108 | .align 3 | |
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109 | .long 1001b, 1006b |
110 | .long 1002b, 1006b | |
111 | .long 1003b, 1006b | |
112 | .long 1004b, 1006b | |
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113 | .previous |
114 | ||
115 | #define instr r4 | |
116 | #define reg r5 | |
117 | #define stack r6 | |
118 | ||
7ab3f8d5 | 119 | .Ldumpstm: stmfd sp!, {instr, reg, stack, r7, lr} |
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120 | mov stack, r0 |
121 | mov instr, r1 | |
7ab3f8d5 | 122 | mov reg, #10 |
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123 | mov r7, #0 |
124 | 1: mov r3, #1 | |
125 | tst instr, r3, lsl reg | |
126 | beq 2f | |
127 | add r7, r7, #1 | |
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128 | teq r7, #6 |
129 | moveq r7, #1 | |
130 | moveq r1, #'\n' | |
131 | movne r1, #' ' | |
132 | ldr r3, [stack], #-4 | |
133 | mov r2, reg | |
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134 | adr r0, .Lfp |
135 | bl printk | |
136 | 2: subs reg, reg, #1 | |
137 | bpl 1b | |
138 | teq r7, #0 | |
139 | adrne r0, .Lcr | |
140 | blne printk | |
7ab3f8d5 | 141 | ldmfd sp!, {instr, reg, stack, r7, pc} |
1da177e4 | 142 | |
7ab3f8d5 | 143 | .Lfp: .asciz "%cr%d:%08x" |
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144 | .Lcr: .asciz "\n" |
145 | .Lbad: .asciz "Backtrace aborted due to bad frame pointer <%p>\n" | |
146 | .align | |
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147 | .Ldsi: .word 0xe92dd800 >> 10 @ stmfd sp!, {... fp, ip, lr, pc} |
148 | .word 0xe92d0000 >> 10 @ stmfd sp!, {} | |
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149 | |
150 | #endif |