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 moveq mask, #0xfc000003 @ mask for 26-bit 42 movne mask, #0 @ mask for 32-bit 43 441: stmfd sp!, {pc} @ calculate offset of PC stored 45 ldr r0, [sp], #4 @ by stmfd for this CPU 46 adr r1, 1b 47 sub offset, r0, r1 48 49/* 50 * Stack frame layout: 51 * optionally saved caller registers (r4 - r10) 52 * saved fp 53 * saved sp 54 * saved lr 55 * frame => saved pc 56 * optionally saved arguments (r0 - r3) 57 * saved sp => <next word> 58 * 59 * Functions start with the following code sequence: 60 * mov ip, sp 61 * stmfd sp!, {r0 - r3} (optional) 62 * corrected pc => stmfd sp!, {..., fp, ip, lr, pc} 63 */ 64for_each_frame: tst frame, mask @ Check for address exceptions 65 bne no_frame 66 671001: ldr sv_pc, [frame, #0] @ get saved pc 681002: ldr sv_fp, [frame, #-12] @ get saved fp 69 70 sub sv_pc, sv_pc, offset @ Correct PC for prefetching 71 bic sv_pc, sv_pc, mask @ mask PC/LR for the mode 72 731003: ldr r2, [sv_pc, #-4] @ if stmfd sp!, {args} exists, 74 ldr r3, .Ldsi+4 @ adjust saved 'pc' back one 75 teq r3, r2, lsr #10 @ instruction 76 subne r0, sv_pc, #4 @ allow for mov 77 subeq r0, sv_pc, #8 @ allow for mov + stmia 78 79 ldr r1, [frame, #-4] @ get saved lr 80 mov r2, frame 81 bic r1, r1, mask @ mask PC/LR for the mode 82 bl dump_backtrace_entry 83 84 ldr r1, [sv_pc, #-4] @ if stmfd sp!, {args} exists, 85 ldr r3, .Ldsi+4 86 teq r3, r1, lsr #10 87 ldreq r0, [frame, #-8] @ get sp 88 subeq r0, r0, #4 @ point at the last arg 89 bleq .Ldumpstm @ dump saved registers 90 911004: ldr r1, [sv_pc, #0] @ if stmfd sp!, {..., fp, ip, lr, pc} 92 ldr r3, .Ldsi @ instruction exists, 93 teq r3, r1, lsr #10 94 subeq r0, frame, #16 95 bleq .Ldumpstm @ dump saved registers 96 97 teq sv_fp, #0 @ zero saved fp means 98 beq no_frame @ no further frames 99 100 cmp sv_fp, frame @ next frame must be 101 mov frame, sv_fp @ above the current frame 102 bhi for_each_frame 103 1041006: adr r0, .Lbad 105 mov r1, frame 106 bl printk 107no_frame: ldmfd sp!, {r4 - r8, pc} 108ENDPROC(__backtrace) 109ENDPROC(c_backtrace) 110 111 .section __ex_table,"a" 112 .align 3 113 .long 1001b, 1006b 114 .long 1002b, 1006b 115 .long 1003b, 1006b 116 .long 1004b, 1006b 117 .previous 118 119#define instr r4 120#define reg r5 121#define stack r6 122 123.Ldumpstm: stmfd sp!, {instr, reg, stack, r7, lr} 124 mov stack, r0 125 mov instr, r1 126 mov reg, #10 127 mov r7, #0 1281: mov r3, #1 129 tst instr, r3, lsl reg 130 beq 2f 131 add r7, r7, #1 132 teq r7, #6 133 moveq r7, #1 134 moveq r1, #'\n' 135 movne r1, #' ' 136 ldr r3, [stack], #-4 137 mov r2, reg 138 adr r0, .Lfp 139 bl printk 1402: subs reg, reg, #1 141 bpl 1b 142 teq r7, #0 143 adrne r0, .Lcr 144 blne printk 145 ldmfd sp!, {instr, reg, stack, r7, pc} 146 147.Lfp: .asciz "%cr%d:%08x" 148.Lcr: .asciz "\n" 149.Lbad: .asciz "Backtrace aborted due to bad frame pointer <%p>\n" 150 .align 151.Ldsi: .word 0xe92dd800 >> 10 @ stmfd sp!, {... fp, ip, lr, pc} 152 .word 0xe92d0000 >> 10 @ stmfd sp!, {} 153 154#endif 155