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d2912cb1 | 1 | /* SPDX-License-Identifier: GPL-2.0-only */ |
1da177e4 LT |
2 | /* |
3 | * linux/arch/arm/lib/backtrace.S | |
4 | * | |
5 | * Copyright (C) 1995, 1996 Russell King | |
6 | * | |
1da177e4 | 7 | * 27/03/03 Ian Molton Clean up CONFIG_CPU |
1da177e4 | 8 | */ |
24c66dfd | 9 | #include <linux/kern_levels.h> |
1da177e4 LT |
10 | #include <linux/linkage.h> |
11 | #include <asm/assembler.h> | |
12 | .text | |
13 | ||
14 | @ fp is 0 or stack frame | |
15 | ||
16 | #define frame r4 | |
7ab3f8d5 RK |
17 | #define sv_fp r5 |
18 | #define sv_pc r6 | |
1da177e4 LT |
19 | #define mask r7 |
20 | #define offset r8 | |
5489ab50 | 21 | #define loglvl r9 |
1da177e4 | 22 | |
1da177e4 LT |
23 | ENTRY(c_backtrace) |
24 | ||
3ee357f0 | 25 | #if !defined(CONFIG_FRAME_POINTER) || !defined(CONFIG_PRINTK) |
6ebbf2ce | 26 | ret lr |
93ed3970 | 27 | ENDPROC(c_backtrace) |
1da177e4 | 28 | #else |
5489ab50 | 29 | stmfd sp!, {r4 - r9, lr} @ Save an extra register so we have a location... |
7ab3f8d5 RK |
30 | movs frame, r0 @ if frame pointer is zero |
31 | beq no_frame @ we have no stack frames | |
5489ab50 | 32 | mov loglvl, r2 |
7ab3f8d5 RK |
33 | |
34 | tst r1, #0x10 @ 26 or 32-bit mode? | |
8b592783 CM |
35 | ARM( moveq mask, #0xfc000003 ) |
36 | THUMB( moveq mask, #0xfc000000 ) | |
37 | THUMB( orreq mask, #0x03 ) | |
7ab3f8d5 RK |
38 | movne mask, #0 @ mask for 32-bit |
39 | ||
40 | 1: stmfd sp!, {pc} @ calculate offset of PC stored | |
41 | ldr r0, [sp], #4 @ by stmfd for this CPU | |
42 | adr r1, 1b | |
1da177e4 LT |
43 | sub offset, r0, r1 |
44 | ||
7ab3f8d5 RK |
45 | /* |
46 | * Stack frame layout: | |
47 | * optionally saved caller registers (r4 - r10) | |
48 | * saved fp | |
49 | * saved sp | |
50 | * saved lr | |
51 | * frame => saved pc | |
52 | * optionally saved arguments (r0 - r3) | |
53 | * saved sp => <next word> | |
54 | * | |
55 | * Functions start with the following code sequence: | |
56 | * mov ip, sp | |
57 | * stmfd sp!, {r0 - r3} (optional) | |
58 | * corrected pc => stmfd sp!, {..., fp, ip, lr, pc} | |
59 | */ | |
60 | for_each_frame: tst frame, mask @ Check for address exceptions | |
61 | bne no_frame | |
62 | ||
63 | 1001: ldr sv_pc, [frame, #0] @ get saved pc | |
64 | 1002: ldr sv_fp, [frame, #-12] @ get saved fp | |
1da177e4 | 65 | |
7ab3f8d5 RK |
66 | sub sv_pc, sv_pc, offset @ Correct PC for prefetching |
67 | bic sv_pc, sv_pc, mask @ mask PC/LR for the mode | |
68 | ||
69 | 1003: ldr r2, [sv_pc, #-4] @ if stmfd sp!, {args} exists, | |
70 | ldr r3, .Ldsi+4 @ adjust saved 'pc' back one | |
69389837 | 71 | teq r3, r2, lsr #11 @ instruction |
7ab3f8d5 RK |
72 | subne r0, sv_pc, #4 @ allow for mov |
73 | subeq r0, sv_pc, #8 @ allow for mov + stmia | |
74 | ||
75 | ldr r1, [frame, #-4] @ get saved lr | |
76 | mov r2, frame | |
77 | bic r1, r1, mask @ mask PC/LR for the mode | |
5489ab50 | 78 | mov r3, loglvl |
1da177e4 LT |
79 | bl dump_backtrace_entry |
80 | ||
7ab3f8d5 RK |
81 | ldr r1, [sv_pc, #-4] @ if stmfd sp!, {args} exists, |
82 | ldr r3, .Ldsi+4 | |
ef41b5c9 | 83 | teq r3, r1, lsr #11 |
7ab3f8d5 RK |
84 | ldreq r0, [frame, #-8] @ get sp |
85 | subeq r0, r0, #4 @ point at the last arg | |
5489ab50 | 86 | mov r2, loglvl |
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 |
5489ab50 | 93 | mov r2, loglvl |
24c66dfd | 94 | bleq dump_backtrace_stm @ dump saved registers |
7ab3f8d5 RK |
95 | |
96 | teq sv_fp, #0 @ zero saved fp means | |
97 | beq no_frame @ no further frames | |
98 | ||
99 | cmp sv_fp, frame @ next frame must be | |
100 | mov frame, sv_fp @ above the current frame | |
101 | bhi for_each_frame | |
102 | ||
103 | 1006: adr r0, .Lbad | |
5489ab50 DS |
104 | mov r1, loglvl |
105 | mov r2, frame | |
1da177e4 | 106 | bl printk |
5489ab50 | 107 | no_frame: ldmfd sp!, {r4 - r9, pc} |
93ed3970 | 108 | ENDPROC(c_backtrace) |
1da177e4 | 109 | |
4260415f | 110 | .pushsection __ex_table,"a" |
1da177e4 | 111 | .align 3 |
7ab3f8d5 RK |
112 | .long 1001b, 1006b |
113 | .long 1002b, 1006b | |
114 | .long 1003b, 1006b | |
115 | .long 1004b, 1006b | |
4260415f | 116 | .popsection |
1da177e4 | 117 | |
5489ab50 | 118 | .Lbad: .asciz "%sBacktrace aborted due to bad frame pointer <%p>\n" |
1da177e4 | 119 | .align |
ef41b5c9 RK |
120 | .Ldsi: .word 0xe92dd800 >> 11 @ stmfd sp!, {... fp, ip, lr, pc} |
121 | .word 0xe92d0000 >> 11 @ stmfd sp!, {} | |
1da177e4 LT |
122 | |
123 | #endif |