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131 lines
3.4 KiB
131 lines
3.4 KiB
/* SPDX-License-Identifier: GPL-2.0-only */ |
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/* |
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* linux/arch/arm/lib/backtrace.S |
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* |
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* Copyright (C) 1995, 1996 Russell King |
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* |
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* 27/03/03 Ian Molton Clean up CONFIG_CPU |
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*/ |
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#include <linux/kern_levels.h> |
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#include <linux/linkage.h> |
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#include <asm/assembler.h> |
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.text |
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@ fp is 0 or stack frame |
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#define frame r4 |
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#define sv_fp r5 |
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#define sv_pc r6 |
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#define mask r7 |
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#define offset r8 |
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#define loglvl r9 |
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ENTRY(c_backtrace) |
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#if !defined(CONFIG_FRAME_POINTER) || !defined(CONFIG_PRINTK) |
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ret lr |
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ENDPROC(c_backtrace) |
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#else |
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stmfd sp!, {r4 - r9, lr} @ Save an extra register so we have a location... |
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movs frame, r0 @ if frame pointer is zero |
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beq no_frame @ we have no stack frames |
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mov loglvl, r2 |
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tst r1, #0x10 @ 26 or 32-bit mode? |
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ARM( moveq mask, #0xfc000003 ) |
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THUMB( moveq mask, #0xfc000000 ) |
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THUMB( orreq mask, #0x03 ) |
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movne mask, #0 @ mask for 32-bit |
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1: stmfd sp!, {pc} @ calculate offset of PC stored |
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ldr r0, [sp], #4 @ by stmfd for this CPU |
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adr r1, 1b |
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sub offset, r0, r1 |
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/* |
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* Stack frame layout: |
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* optionally saved caller registers (r4 - r10) |
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* saved fp |
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* saved sp |
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* saved lr |
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* frame => saved pc |
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* optionally saved arguments (r0 - r3) |
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* saved sp => <next word> |
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* |
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* Functions start with the following code sequence: |
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* mov ip, sp |
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* stmfd sp!, {r0 - r3} (optional) |
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* corrected pc => stmfd sp!, {..., fp, ip, lr, pc} |
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*/ |
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for_each_frame: tst frame, mask @ Check for address exceptions |
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bne no_frame |
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1001: ldr sv_pc, [frame, #0] @ get saved pc |
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1002: ldr sv_fp, [frame, #-12] @ get saved fp |
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sub sv_pc, sv_pc, offset @ Correct PC for prefetching |
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bic sv_pc, sv_pc, mask @ mask PC/LR for the mode |
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1003: ldr r2, [sv_pc, #-4] @ if stmfd sp!, {args} exists, |
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ldr r3, .Ldsi+4 @ adjust saved 'pc' back one |
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teq r3, r2, lsr #11 @ instruction |
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subne r0, sv_pc, #4 @ allow for mov |
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subeq r0, sv_pc, #8 @ allow for mov + stmia |
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ldr r1, [frame, #-4] @ get saved lr |
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mov r2, frame |
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bic r1, r1, mask @ mask PC/LR for the mode |
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mov r3, loglvl |
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bl dump_backtrace_entry |
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ldr r1, [sv_pc, #-4] @ if stmfd sp!, {args} exists, |
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ldr r3, .Ldsi+4 |
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teq r3, r1, lsr #11 |
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ldreq r0, [frame, #-8] @ get sp |
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subeq r0, r0, #4 @ point at the last arg |
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mov r2, loglvl |
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bleq dump_backtrace_stm @ dump saved registers |
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1004: ldr r1, [sv_pc, #0] @ if stmfd sp!, {..., fp, ip, lr, pc} |
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ldr r3, .Ldsi @ instruction exists, |
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teq r3, r1, lsr #11 |
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subeq r0, frame, #16 |
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mov r2, loglvl |
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bleq dump_backtrace_stm @ dump saved registers |
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teq sv_fp, #0 @ zero saved fp means |
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beq no_frame @ no further frames |
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cmp sv_fp, frame @ next frame must be |
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mov frame, sv_fp @ above the current frame |
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#ifdef CONFIG_IRQSTACKS |
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@ |
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@ Kernel stacks may be discontiguous in memory. If the next |
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@ frame is below the previous frame, accept it as long as it |
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@ lives in kernel memory. |
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@ |
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cmpls sv_fp, #PAGE_OFFSET |
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#endif |
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bhi for_each_frame |
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1006: adr r0, .Lbad |
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mov r1, loglvl |
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mov r2, frame |
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bl _printk |
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no_frame: ldmfd sp!, {r4 - r9, pc} |
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ENDPROC(c_backtrace) |
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.pushsection __ex_table,"a" |
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.align 3 |
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.long 1001b, 1006b |
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.long 1002b, 1006b |
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.long 1003b, 1006b |
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.long 1004b, 1006b |
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.popsection |
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.Lbad: .asciz "%sBacktrace aborted due to bad frame pointer <%p>\n" |
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.align |
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.Ldsi: .word 0xe92dd800 >> 11 @ stmfd sp!, {... fp, ip, lr, pc} |
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.word 0xe92d0000 >> 11 @ stmfd sp!, {} |
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#endif
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