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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
Linus Torvalds1da177e2005-04-16 15:20:36 -070025ENTRY(c_backtrace)
26
Malcolm Parsons3ee357f2006-03-25 21:58:03 +000027#if !defined(CONFIG_FRAME_POINTER) || !defined(CONFIG_PRINTK)
Linus Torvalds1da177e2005-04-16 15:20:36 -070028 mov pc, lr
Catalin Marinas93ed3972008-08-28 11:22:32 +010029ENDPROC(c_backtrace)
Linus Torvalds1da177e2005-04-16 15:20:36 -070030#else
Linus Torvalds1da177e2005-04-16 15:20:36 -070031 stmfd sp!, {r4 - r8, lr} @ Save an extra register so we have a location...
Russell King7ab3f8d2007-03-02 15:01:36 +000032 movs frame, r0 @ if frame pointer is zero
33 beq no_frame @ we have no stack frames
Linus Torvalds1da177e2005-04-16 15:20:36 -070034
Russell King7ab3f8d2007-03-02 15:01:36 +000035 tst r1, #0x10 @ 26 or 32-bit mode?
Catalin Marinas8b592782009-07-24 12:32:57 +010036 ARM( moveq mask, #0xfc000003 )
37 THUMB( moveq mask, #0xfc000000 )
38 THUMB( orreq mask, #0x03 )
Russell King7ab3f8d2007-03-02 15:01:36 +000039 movne mask, #0 @ mask for 32-bit
40
411: stmfd sp!, {pc} @ calculate offset of PC stored
42 ldr r0, [sp], #4 @ by stmfd for this CPU
43 adr r1, 1b
Linus Torvalds1da177e2005-04-16 15:20:36 -070044 sub offset, r0, r1
45
Russell King7ab3f8d2007-03-02 15:01:36 +000046/*
47 * Stack frame layout:
48 * optionally saved caller registers (r4 - r10)
49 * saved fp
50 * saved sp
51 * saved lr
52 * frame => saved pc
53 * optionally saved arguments (r0 - r3)
54 * saved sp => <next word>
55 *
56 * Functions start with the following code sequence:
57 * mov ip, sp
58 * stmfd sp!, {r0 - r3} (optional)
59 * corrected pc => stmfd sp!, {..., fp, ip, lr, pc}
60 */
61for_each_frame: tst frame, mask @ Check for address exceptions
62 bne no_frame
Linus Torvalds1da177e2005-04-16 15:20:36 -070063
Russell King7ab3f8d2007-03-02 15:01:36 +0000641001: ldr sv_pc, [frame, #0] @ get saved pc
651002: ldr sv_fp, [frame, #-12] @ get saved fp
66
67 sub sv_pc, sv_pc, offset @ Correct PC for prefetching
68 bic sv_pc, sv_pc, mask @ mask PC/LR for the mode
69
701003: ldr r2, [sv_pc, #-4] @ if stmfd sp!, {args} exists,
71 ldr r3, .Ldsi+4 @ adjust saved 'pc' back one
72 teq r3, r2, lsr #10 @ instruction
73 subne r0, sv_pc, #4 @ allow for mov
74 subeq r0, sv_pc, #8 @ allow for mov + stmia
75
76 ldr r1, [frame, #-4] @ get saved lr
77 mov r2, frame
78 bic r1, r1, mask @ mask PC/LR for the mode
Linus Torvalds1da177e2005-04-16 15:20:36 -070079 bl dump_backtrace_entry
80
Russell King7ab3f8d2007-03-02 15:01:36 +000081 ldr r1, [sv_pc, #-4] @ if stmfd sp!, {args} exists,
82 ldr r3, .Ldsi+4
83 teq r3, r1, lsr #10
84 ldreq r0, [frame, #-8] @ get sp
85 subeq r0, r0, #4 @ point at the last arg
86 bleq .Ldumpstm @ dump saved registers
Linus Torvalds1da177e2005-04-16 15:20:36 -070087
Russell King7ab3f8d2007-03-02 15:01:36 +0000881004: ldr r1, [sv_pc, #0] @ if stmfd sp!, {..., fp, ip, lr, pc}
89 ldr r3, .Ldsi @ instruction exists,
90 teq r3, r1, lsr #10
91 subeq r0, frame, #16
92 bleq .Ldumpstm @ dump saved registers
Linus Torvalds1da177e2005-04-16 15:20:36 -070093
Russell King7ab3f8d2007-03-02 15:01:36 +000094 teq sv_fp, #0 @ zero saved fp means
95 beq no_frame @ no further frames
Linus Torvalds1da177e2005-04-16 15:20:36 -070096
Russell King7ab3f8d2007-03-02 15:01:36 +000097 cmp sv_fp, frame @ next frame must be
98 mov frame, sv_fp @ above the current frame
99 bhi for_each_frame
Linus Torvalds1da177e2005-04-16 15:20:36 -0700100
Russell King7ab3f8d2007-03-02 15:01:36 +00001011006: adr r0, .Lbad
Linus Torvalds1da177e2005-04-16 15:20:36 -0700102 mov r1, frame
103 bl printk
Russell King7ab3f8d2007-03-02 15:01:36 +0000104no_frame: ldmfd sp!, {r4 - r8, pc}
Catalin Marinas93ed3972008-08-28 11:22:32 +0100105ENDPROC(c_backtrace)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700106
Russell King42604152010-04-19 10:15:03 +0100107 .pushsection __ex_table,"a"
Linus Torvalds1da177e2005-04-16 15:20:36 -0700108 .align 3
Russell King7ab3f8d2007-03-02 15:01:36 +0000109 .long 1001b, 1006b
110 .long 1002b, 1006b
111 .long 1003b, 1006b
112 .long 1004b, 1006b
Russell King42604152010-04-19 10:15:03 +0100113 .popsection
Linus Torvalds1da177e2005-04-16 15:20:36 -0700114
115#define instr r4
116#define reg r5
117#define stack r6
118
Russell King7ab3f8d2007-03-02 15:01:36 +0000119.Ldumpstm: stmfd sp!, {instr, reg, stack, r7, lr}
Linus Torvalds1da177e2005-04-16 15:20:36 -0700120 mov stack, r0
121 mov instr, r1
Russell King7ab3f8d2007-03-02 15:01:36 +0000122 mov reg, #10
Linus Torvalds1da177e2005-04-16 15:20:36 -0700123 mov r7, #0
1241: mov r3, #1
Catalin Marinas8b592782009-07-24 12:32:57 +0100125 ARM( tst instr, r3, lsl reg )
126 THUMB( lsl r3, reg )
127 THUMB( tst instr, r3 )
Linus Torvalds1da177e2005-04-16 15:20:36 -0700128 beq 2f
129 add r7, r7, #1
Russell King7ab3f8d2007-03-02 15:01:36 +0000130 teq r7, #6
131 moveq r7, #1
132 moveq r1, #'\n'
133 movne r1, #' '
134 ldr r3, [stack], #-4
135 mov r2, reg
Linus Torvalds1da177e2005-04-16 15:20:36 -0700136 adr r0, .Lfp
137 bl printk
1382: subs reg, reg, #1
139 bpl 1b
140 teq r7, #0
141 adrne r0, .Lcr
142 blne printk
Russell King7ab3f8d2007-03-02 15:01:36 +0000143 ldmfd sp!, {instr, reg, stack, r7, pc}
Linus Torvalds1da177e2005-04-16 15:20:36 -0700144
Russell King7ab3f8d2007-03-02 15:01:36 +0000145.Lfp: .asciz "%cr%d:%08x"
Linus Torvalds1da177e2005-04-16 15:20:36 -0700146.Lcr: .asciz "\n"
147.Lbad: .asciz "Backtrace aborted due to bad frame pointer <%p>\n"
148 .align
Russell King7ab3f8d2007-03-02 15:01:36 +0000149.Ldsi: .word 0xe92dd800 >> 10 @ stmfd sp!, {... fp, ip, lr, pc}
150 .word 0xe92d0000 >> 10 @ stmfd sp!, {}
Linus Torvalds1da177e2005-04-16 15:20:36 -0700151
152#endif