backtrace.S
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/*
* linux/arch/unicore32/lib/backtrace.S
*
* Code specific to PKUnity SoC and UniCore ISA
*
* Copyright (C) 2001-2010 GUAN Xue-tao
*
* 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.
*/
#include <linux/linkage.h>
#include <asm/assembler.h>
.text
@ fp is 0 or stack frame
#define frame v4
#define sv_fp v5
#define sv_pc v6
#define offset v8
ENTRY(__backtrace)
mov r0, fp
ENTRY(c_backtrace)
#if !defined(CONFIG_FRAME_POINTER) || !defined(CONFIG_PRINTK)
mov pc, lr
ENDPROC(__backtrace)
ENDPROC(c_backtrace)
#else
stm.w (v4 - v8, lr), [sp-] @ Save an extra register
@ so we have a location...
mov.a frame, r0 @ if frame pointer is zero
beq no_frame @ we have no stack frames
1: stm.w (pc), [sp-] @ calculate offset of PC stored
ldw.w 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
* stm.w (r0 - r3), [sp-] (optional)
* corrected pc => stm.w sp, (..., fp, ip, lr, pc)
*/
for_each_frame:
1001: ldw sv_pc, [frame+], #0 @ get saved pc
1002: ldw sv_fp, [frame+], #-12 @ get saved fp
sub sv_pc, sv_pc, offset @ Correct PC for prefetching
1003: ldw r2, [sv_pc+], #-4 @ if stmfd sp, {args} exists,
ldw r3, .Ldsi+4 @ adjust saved 'pc' back one
cxor.a r3, r2 >> #14 @ instruction
beq 201f
sub r0, sv_pc, #4 @ allow for mov
b 202f
201:
sub r0, sv_pc, #8 @ allow for mov + stmia
202:
ldw r1, [frame+], #-4 @ get saved lr
mov r2, frame
b.l dump_backtrace_entry
ldw r1, [sv_pc+], #-4 @ if stmfd sp, {args} exists,
ldw r3, .Ldsi+4
cxor.a r3, r1 >> #14
bne 1004f
ldw r0, [frame+], #-8 @ get sp
sub r0, r0, #4 @ point at the last arg
b.l .Ldumpstm @ dump saved registers
1004: ldw r1, [sv_pc+], #0 @ if stmfd {, fp, ip, lr, pc}
ldw r3, .Ldsi @ instruction exists,
cxor.a r3, r1 >> #14
bne 201f
sub r0, frame, #16
b.l .Ldumpstm @ dump saved registers
201:
cxor.a sv_fp, #0 @ zero saved fp means
beq no_frame @ no further frames
csub.a sv_fp, frame @ next frame must be
mov frame, sv_fp @ above the current frame
bua for_each_frame
1006: adr r0, .Lbad
mov r1, frame
b.l printk
no_frame: ldm.w (v4 - v8, pc), [sp]+
ENDPROC(__backtrace)
ENDPROC(c_backtrace)
.pushsection __ex_table,"a"
.align 3
.long 1001b, 1006b
.long 1002b, 1006b
.long 1003b, 1006b
.long 1004b, 1006b
.popsection
#define instr v4
#define reg v5
#define stack v6
.Ldumpstm: stm.w (instr, reg, stack, v7, lr), [sp-]
mov stack, r0
mov instr, r1
mov reg, #14
mov v7, #0
1: mov r3, #1
csub.a reg, #8
bne 201f
sub reg, reg, #3
201:
cand.a instr, r3 << reg
beq 2f
add v7, v7, #1
cxor.a v7, #6
cmoveq v7, #1
cmoveq r1, #'\n'
cmovne r1, #' '
ldw.w r3, [stack]+, #-4
mov r2, reg
csub.a r2, #8
bsl 201f
sub r2, r2, #3
201:
cand.a instr, #0x40 @ if H is 1, high 16 regs
beq 201f
add r2, r2, #0x10 @ so r2 need add 16
201:
adr r0, .Lfp
b.l printk
2: sub.a reg, reg, #1
bns 1b
cxor.a v7, #0
beq 201f
adr r0, .Lcr
b.l printk
201: ldm.w (instr, reg, stack, v7, pc), [sp]+
.Lfp: .asciz "%cr%d:%08x"
.Lcr: .asciz "\n"
.Lbad: .asciz "Backtrace aborted due to bad frame pointer <%p>\n"
.align
.Ldsi: .word 0x92eec000 >> 14 @ stm.w sp, (... fp, ip, lr, pc)
.word 0x92e10000 >> 14 @ stm.w sp, ()
#endif