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1da177e4 LT |
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 | */ | |
24c66dfd | 13 | #include <linux/kern_levels.h> |
1da177e4 LT |
14 | #include <linux/linkage.h> |
15 | #include <asm/assembler.h> | |
16 | .text | |
17 | ||
18 | @ fp is 0 or stack frame | |
19 | ||
20 | #define frame r4 | |
7ab3f8d5 RK |
21 | #define sv_fp r5 |
22 | #define sv_pc r6 | |
1da177e4 LT |
23 | #define mask r7 |
24 | #define offset r8 | |
25 | ||
1da177e4 LT |
26 | ENTRY(c_backtrace) |
27 | ||
3ee357f0 | 28 | #if !defined(CONFIG_FRAME_POINTER) || !defined(CONFIG_PRINTK) |
6ebbf2ce | 29 | ret lr |
93ed3970 | 30 | ENDPROC(c_backtrace) |
1da177e4 | 31 | #else |
1da177e4 | 32 | stmfd sp!, {r4 - r8, lr} @ Save an extra register so we have a location... |
7ab3f8d5 RK |
33 | movs frame, r0 @ if frame pointer is zero |
34 | beq no_frame @ we have no stack frames | |
35 | ||
36 | tst r1, #0x10 @ 26 or 32-bit mode? | |
8b592783 CM |
37 | ARM( moveq mask, #0xfc000003 ) |
38 | THUMB( moveq mask, #0xfc000000 ) | |
39 | THUMB( orreq mask, #0x03 ) | |
7ab3f8d5 RK |
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 | |
7ab3f8d5 RK |
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 | ||
7ab3f8d5 RK |
82 | ldr r1, [sv_pc, #-4] @ if stmfd sp!, {args} exists, |
83 | ldr r3, .Ldsi+4 | |
ef41b5c9 | 84 | teq r3, r1, lsr #11 |
7ab3f8d5 RK |
85 | ldreq r0, [frame, #-8] @ get sp |
86 | subeq r0, r0, #4 @ point at the last arg | |
24c66dfd | 87 | bleq dump_backtrace_stm @ dump saved registers |
1da177e4 | 88 | |
7ab3f8d5 RK |
89 | 1004: ldr r1, [sv_pc, #0] @ if stmfd sp!, {..., fp, ip, lr, pc} |
90 | ldr r3, .Ldsi @ instruction exists, | |
ef41b5c9 | 91 | teq r3, r1, lsr #11 |
7ab3f8d5 | 92 | subeq r0, frame, #16 |
24c66dfd | 93 | bleq dump_backtrace_stm @ dump saved registers |
7ab3f8d5 RK |
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} |
93ed3970 | 106 | ENDPROC(c_backtrace) |
1da177e4 | 107 | |
4260415f | 108 | .pushsection __ex_table,"a" |
1da177e4 | 109 | .align 3 |
7ab3f8d5 RK |
110 | .long 1001b, 1006b |
111 | .long 1002b, 1006b | |
112 | .long 1003b, 1006b | |
113 | .long 1004b, 1006b | |
4260415f | 114 | .popsection |
1da177e4 | 115 | |
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116 | .Lbad: .asciz "Backtrace aborted due to bad frame pointer <%p>\n" |
117 | .align | |
ef41b5c9 RK |
118 | .Ldsi: .word 0xe92dd800 >> 11 @ stmfd sp!, {... fp, ip, lr, pc} |
119 | .word 0xe92d0000 >> 11 @ stmfd sp!, {} | |
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120 | |
121 | #endif |