/* * linux/arch/arm/lib/backtrace.S * * Copyright (C) 1995, 1996 Russell King * * This program is free software; you can redistribute it and/or modify * it under the terms of the GNU General Public License version 2 as * published by the Free Software Foundation. * * 27/03/03 Ian Molton Clean up CONFIG_CPU * */ #include <linux/linkage.h> #include <asm/assembler.h> .text @ fp is 0 or stack frame #define frame r4 #define sv_fp r5 #define sv_pc r6 #define mask r7 #define offset r8 ENTRY(__backtrace) mov r1, #0x10 mov r0, fp ENTRY(c_backtrace) #if !defined(CONFIG_FRAME_POINTER) || !defined(CONFIG_PRINTK) mov pc, lr ENDPROC(__backtrace) ENDPROC(c_backtrace) #else stmfd sp!, {r4 - r8, lr} @ Save an extra register so we have a location... movs frame, r0 @ if frame pointer is zero beq no_frame @ we have no stack frames tst r1, #0x10 @ 26 or 32-bit mode? moveq mask, #0xfc000003 @ mask for 26-bit movne mask, #0 @ mask for 32-bit 1: stmfd sp!, {pc} @ calculate offset of PC stored ldr r0, [sp], #4 @ by stmfd for this CPU adr r1, 1b sub offset, r0, r1 /* * Stack frame layout: * optionally saved caller registers (r4 - r10) * saved fp * saved sp * saved lr * frame => saved pc * optionally saved arguments (r0 - r3) * saved sp => <next word> * * Functions start with the following code sequence: * mov ip, sp * stmfd sp!, {r0 - r3} (optional) * corrected pc => stmfd sp!, {..., fp, ip, lr, pc} */ for_each_frame: tst frame, mask @ Check for address exceptions bne no_frame 1001: ldr sv_pc, [frame, #0] @ get saved pc 1002: ldr sv_fp, [frame, #-12] @ get saved fp sub sv_pc, sv_pc, offset @ Correct PC for prefetching bic sv_pc, sv_pc, mask @ mask PC/LR for the mode 1003: ldr r2, [sv_pc, #-4] @ if stmfd sp!, {args} exists, ldr r3, .Ldsi+4 @ adjust saved 'pc' back one teq r3, r2, lsr #10 @ instruction subne r0, sv_pc, #4 @ allow for mov subeq r0, sv_pc, #8 @ allow for mov + stmia ldr r1, [frame, #-4] @ get saved lr mov r2, frame bic r1, r1, mask @ mask PC/LR for the mode bl dump_backtrace_entry ldr r1, [sv_pc, #-4] @ if stmfd sp!, {args} exists, ldr r3, .Ldsi+4 teq r3, r1, lsr #10 ldreq r0, [frame, #-8] @ get sp subeq r0, r0, #4 @ point at the last arg bleq .Ldumpstm @ dump saved registers 1004: ldr r1, [sv_pc, #0] @ if stmfd sp!, {..., fp, ip, lr, pc} ldr r3, .Ldsi @ instruction exists, teq r3, r1, lsr #10 subeq r0, frame, #16 bleq .Ldumpstm @ dump saved registers teq sv_fp, #0 @ zero saved fp means beq no_frame @ no further frames cmp sv_fp, frame @ next frame must be mov frame, sv_fp @ above the current frame bhi for_each_frame 1006: adr r0, .Lbad mov r1, frame bl printk no_frame: ldmfd sp!, {r4 - r8, pc} ENDPROC(__backtrace) ENDPROC(c_backtrace) .section __ex_table,"a" .align 3 .long 1001b, 1006b .long 1002b, 1006b .long 1003b, 1006b .long 1004b, 1006b .previous #define instr r4 #define reg r5 #define stack r6 .Ldumpstm: stmfd sp!, {instr, reg, stack, r7, lr} mov stack, r0 mov instr, r1 mov reg, #10 mov r7, #0 1: mov r3, #1 tst instr, r3, lsl reg beq 2f add r7, r7, #1 teq r7, #6 moveq r7, #1 moveq r1, #'\n' movne r1, #' ' ldr r3, [stack], #-4 mov r2, reg adr r0, .Lfp bl printk 2: subs reg, reg, #1 bpl 1b teq r7, #0 adrne r0, .Lcr blne printk ldmfd sp!, {instr, reg, stack, r7, pc} .Lfp: .asciz "%cr%d:%08x" .Lcr: .asciz "\n" .Lbad: .asciz "Backtrace aborted due to bad frame pointer <%p>\n" .align .Ldsi: .word 0xe92dd800 >> 10 @ stmfd sp!, {... fp, ip, lr, pc} .word 0xe92d0000 >> 10 @ stmfd sp!, {} #endif