1/*
2 *  linux/arch/arm26/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#include <linux/linkage.h>
11#include <asm/assembler.h>
12		.text
13
14@ fp is 0 or stack frame
15
16#define frame	r4
17#define next	r5
18#define save	r6
19#define mask	r7
20#define offset	r8
21
22ENTRY(__backtrace)
23		mov	r1, #0x10
24		mov	r0, fp
25
26ENTRY(c_backtrace)
27
28#ifdef CONFIG_NO_FRAME_POINTER
29		mov	pc, lr
30#else
31
32		stmfd	sp!, {r4 - r8, lr}	@ Save an extra register so we have a location...
33		mov	mask, #0xfc000003
34		tst	mask, r0
35		movne	r0, #0
36		movs	frame, r0
371:		moveq	r0, #-2
38		LOADREGS(eqfd, sp!, {r4 - r8, pc})
39
402:		stmfd	sp!, {pc}		@ calculate offset of PC in STMIA instruction
41		ldr	r0, [sp], #4
42		adr	r1, 2b - 4
43		sub	offset, r0, r1
44
453:		tst	frame, mask		@ Check for address exceptions...
46		bne	1b
47
481001:		ldr	next, [frame, #-12]	@ get fp
491002:		ldr	r2, [frame, #-4]	@ get lr
501003:		ldr	r3, [frame, #0]		@ get pc
51		sub	save, r3, offset	@ Correct PC for prefetching
52		bic	save, save, mask
531004:		ldr	r1, [save, #0]		@ get instruction at function
54		mov	r1, r1, lsr #10
55		ldr	r3, .Ldsi+4
56		teq	r1, r3
57		subeq	save, save, #4
58		adr	r0, .Lfe
59		mov	r1, save
60		bic	r2, r2, mask
61		bl	printk			@ print pc and link register
62
63		ldr	r0, [frame, #-8]	@ get sp
64		sub	r0, r0, #4
651005:		ldr	r1, [save, #4]		@ get instruction at function+4
66		mov	r3, r1, lsr #10
67		ldr	r2, .Ldsi+4
68		teq	r3, r2			@ Check for stmia sp!, {args}
69		addeq	save, save, #4		@ next instruction
70		bleq	.Ldumpstm
71
72		sub	r0, frame, #16
731006:		ldr	r1, [save, #4]		@ Get 'stmia sp!, {rlist, fp, ip, lr, pc}' instruction
74		mov	r3, r1, lsr #10
75		ldr	r2, .Ldsi
76		teq	r3, r2
77		bleq	.Ldumpstm
78
79		teq	frame, next
80		movne	frame, next
81		teqne	frame, #0
82		bne	3b
83		LOADREGS(fd, sp!, {r4 - r8, pc})
84
85/*
86 * Fixup for LDMDB
87 */
88		.section .fixup,"ax"
89		.align	0
901007:		ldr	r0, =.Lbad
91		mov	r1, frame
92		bl	printk
93		LOADREGS(fd, sp!, {r4 - r8, pc})
94		.ltorg
95		.previous
96
97		.section __ex_table,"a"
98		.align	3
99		.long	1001b, 1007b
100		.long	1002b, 1007b
101		.long	1003b, 1007b
102		.long	1004b, 1007b
103		.long	1005b, 1007b
104		.long	1006b, 1007b
105		.previous
106
107#define instr r4
108#define reg   r5
109#define stack r6
110
111.Ldumpstm:	stmfd	sp!, {instr, reg, stack, r7, lr}
112		mov	stack, r0
113		mov	instr, r1
114		mov	reg, #9
115		mov	r7, #0
1161:		mov	r3, #1
117		tst	instr, r3, lsl reg
118		beq	2f
119		add	r7, r7, #1
120		teq	r7, #4
121		moveq	r7, #0
122		moveq	r3, #'\n'
123		movne	r3, #' '
124		ldr	r2, [stack], #-4
125		mov	r1, reg
126		adr	r0, .Lfp
127		bl	printk
1282:		subs	reg, reg, #1
129		bpl	1b
130		teq	r7, #0
131		adrne	r0, .Lcr
132		blne	printk
133		mov	r0, stack
134		LOADREGS(fd, sp!, {instr, reg, stack, r7, pc})
135
136.Lfe:		.asciz	"Function entered at [<%p>] from [<%p>]\n"
137.Lfp:		.asciz	" r%d = %08X%c"
138.Lcr:		.asciz	"\n"
139.Lbad:		.asciz	"Backtrace aborted due to bad frame pointer <%p>\n"
140		.align
141.Ldsi:		.word	0x00e92dd8 >> 2
142		.word	0x00e92d00 >> 2
143
144#endif
145