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 */ 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 20#define sv_fp r5 21#define sv_pc r6 22#define mask r7 23#define offset r8 24 25ENTRY(__backtrace) 26 mov r1, #0x10 27 mov r0, fp 28 29ENTRY(c_backtrace) 30 31#if !defined(CONFIG_FRAME_POINTER) || !defined(CONFIG_PRINTK) 32 mov pc, lr 33ENDPROC(__backtrace) 34ENDPROC(c_backtrace) 35#else 36 stmfd sp!, {r4 - r8, lr} @ Save an extra register so we have a location... 37 movs frame, r0 @ if frame pointer is zero 38 beq no_frame @ we have no stack frames 39 40 tst r1, #0x10 @ 26 or 32-bit mode? 41 ARM( moveq mask, #0xfc000003 ) 42 THUMB( moveq mask, #0xfc000000 ) 43 THUMB( orreq mask, #0x03 ) 44 movne mask, #0 @ mask for 32-bit 45 461: stmfd sp!, {pc} @ calculate offset of PC stored 47 ldr r0, [sp], #4 @ by stmfd for this CPU 48 adr r1, 1b 49 sub offset, r0, r1 50 51/* 52 * Stack frame layout: 53 * optionally saved caller registers (r4 - r10) 54 * saved fp 55 * saved sp 56 * saved lr 57 * frame => saved pc 58 * optionally saved arguments (r0 - r3) 59 * saved sp => <next word> 60 * 61 * Functions start with the following code sequence: 62 * mov ip, sp 63 * stmfd sp!, {r0 - r3} (optional) 64 * corrected pc => stmfd sp!, {..., fp, ip, lr, pc} 65 */ 66for_each_frame: tst frame, mask @ Check for address exceptions 67 bne no_frame 68 691001: ldr sv_pc, [frame, #0] @ get saved pc 701002: ldr sv_fp, [frame, #-12] @ get saved fp 71 72 sub sv_pc, sv_pc, offset @ Correct PC for prefetching 73 bic sv_pc, sv_pc, mask @ mask PC/LR for the mode 74 751003: ldr r2, [sv_pc, #-4] @ if stmfd sp!, {args} exists, 76 ldr r3, .Ldsi+4 @ adjust saved 'pc' back one 77 teq r3, r2, lsr #10 @ instruction 78 subne r0, sv_pc, #4 @ allow for mov 79 subeq r0, sv_pc, #8 @ allow for mov + stmia 80 81 ldr r1, [frame, #-4] @ get saved lr 82 mov r2, frame 83 bic r1, r1, mask @ mask PC/LR for the mode 84 bl dump_backtrace_entry 85 86 ldr r1, [sv_pc, #-4] @ if stmfd sp!, {args} exists, 87 ldr r3, .Ldsi+4 88 teq r3, r1, lsr #10 89 ldreq r0, [frame, #-8] @ get sp 90 subeq r0, r0, #4 @ point at the last arg 91 bleq .Ldumpstm @ dump saved registers 92 931004: ldr r1, [sv_pc, #0] @ if stmfd sp!, {..., fp, ip, lr, pc} 94 ldr r3, .Ldsi @ instruction exists, 95 teq r3, r1, lsr #10 96 subeq r0, frame, #16 97 bleq .Ldumpstm @ dump saved registers 98 99 teq sv_fp, #0 @ zero saved fp means 100 beq no_frame @ no further frames 101 102 cmp sv_fp, frame @ next frame must be 103 mov frame, sv_fp @ above the current frame 104 bhi for_each_frame 105 1061006: adr r0, .Lbad 107 mov r1, frame 108 bl printk 109no_frame: ldmfd sp!, {r4 - r8, pc} 110ENDPROC(__backtrace) 111ENDPROC(c_backtrace) 112 113 .pushsection __ex_table,"a" 114 .align 3 115 .long 1001b, 1006b 116 .long 1002b, 1006b 117 .long 1003b, 1006b 118 .long 1004b, 1006b 119 .popsection 120 121#define instr r4 122#define reg r5 123#define stack r6 124 125.Ldumpstm: stmfd sp!, {instr, reg, stack, r7, lr} 126 mov stack, r0 127 mov instr, r1 128 mov reg, #10 129 mov r7, #0 1301: mov r3, #1 131 ARM( tst instr, r3, lsl reg ) 132 THUMB( lsl r3, reg ) 133 THUMB( tst instr, r3 ) 134 beq 2f 135 add r7, r7, #1 136 teq r7, #6 137 moveq r7, #1 138 moveq r1, #'\n' 139 movne r1, #' ' 140 ldr r3, [stack], #-4 141 mov r2, reg 142 adr r0, .Lfp 143 bl printk 1442: subs reg, reg, #1 145 bpl 1b 146 teq r7, #0 147 adrne r0, .Lcr 148 blne printk 149 ldmfd sp!, {instr, reg, stack, r7, pc} 150 151.Lfp: .asciz "%cr%d:%08x" 152.Lcr: .asciz "\n" 153.Lbad: .asciz "Backtrace aborted due to bad frame pointer <%p>\n" 154 .align 155.Ldsi: .word 0xe92dd800 >> 10 @ stmfd sp!, {... fp, ip, lr, pc} 156 .word 0xe92d0000 >> 10 @ stmfd sp!, {} 157 158#endif 159