/arch/unicore32/lib/backtrace.S

  1/* SPDX-License-Identifier: GPL-2.0-only */
  2/*
  3 * linux/arch/unicore32/lib/backtrace.S
  4 *
  5 * Code specific to PKUnity SoC and UniCore ISA
  6 *
  7 * Copyright (C) 2001-2010 GUAN Xue-tao
  8 */
  9#include <linux/linkage.h>
 10#include <asm/assembler.h>
 11		.text
 12
 13@ fp is 0 or stack frame
 14
 15#define frame	v4
 16#define sv_fp	v5
 17#define sv_pc	v6
 18#define offset	v8
 19
 20ENTRY(__backtrace)
 21		mov	r0, fp
 22
 23ENTRY(c_backtrace)
 24
 25#if !defined(CONFIG_FRAME_POINTER) || !defined(CONFIG_PRINTK)
 26		mov	pc, lr
 27ENDPROC(__backtrace)
 28ENDPROC(c_backtrace)
 29#else
 30		stm.w	(v4 - v8, lr), [sp-]	@ Save an extra register
 31						@ so we have a location...
 32		mov.a	frame, r0		@ if frame pointer is zero
 33		beq	no_frame		@ we have no stack frames
 34
 351:		stm.w	(pc), [sp-]		@ calculate offset of PC stored
 36		ldw.w	r0, [sp]+, #4		@ by stmfd for this CPU
 37		adr	r1, 1b
 38		sub	offset, r0, r1
 39
 40/*
 41 * Stack frame layout:
 42 *             optionally saved caller registers (r4 - r10)
 43 *             saved fp
 44 *             saved sp
 45 *             saved lr
 46 *    frame => saved pc
 47 *             optionally saved arguments (r0 - r3)
 48 * saved sp => <next word>
 49 *
 50 * Functions start with the following code sequence:
 51 *                  mov   ip, sp
 52 *                  stm.w (r0 - r3), [sp-] (optional)
 53 * corrected pc =>  stm.w sp, (..., fp, ip, lr, pc)
 54 */
 55for_each_frame:
 56
 571001:		ldw	sv_pc, [frame+], #0	@ get saved pc
 581002:		ldw	sv_fp, [frame+], #-12	@ get saved fp
 59
 60		sub	sv_pc, sv_pc, offset	@ Correct PC for prefetching
 61
 621003:		ldw	r2, [sv_pc+], #-4	@ if stmfd sp, {args} exists,
 63		ldw	r3, .Ldsi+4		@ adjust saved 'pc' back one
 64		cxor.a	r3, r2 >> #14		@ instruction
 65		beq	201f
 66		sub	r0, sv_pc, #4		@ allow for mov
 67		b	202f
 68201:
 69		sub	r0, sv_pc, #8		@ allow for mov + stmia
 70202:
 71		ldw	r1, [frame+], #-4	@ get saved lr
 72		mov	r2, frame
 73		b.l	dump_backtrace_entry
 74
 75		ldw	r1, [sv_pc+], #-4	@ if stmfd sp, {args} exists,
 76		ldw	r3, .Ldsi+4
 77		cxor.a	r3, r1 >> #14
 78		bne	1004f
 79		ldw	r0, [frame+], #-8	@ get sp
 80		sub	r0, r0, #4		@ point at the last arg
 81		b.l	.Ldumpstm		@ dump saved registers
 82
 831004:		ldw	r1, [sv_pc+], #0	@ if stmfd {, fp, ip, lr, pc}
 84		ldw	r3, .Ldsi		@ instruction exists,
 85		cxor.a	r3, r1 >> #14
 86		bne	201f
 87		sub	r0, frame, #16
 88		b.l	.Ldumpstm		@ dump saved registers
 89201:
 90		cxor.a	sv_fp, #0		@ zero saved fp means
 91		beq	no_frame		@ no further frames
 92
 93		csub.a	sv_fp, frame		@ next frame must be
 94		mov	frame, sv_fp		@ above the current frame
 95		bua	for_each_frame
 96
 971006:		adr	r0, .Lbad
 98		mov	r1, frame
 99		b.l	printk
100no_frame:	ldm.w	(v4 - v8, pc), [sp]+
101ENDPROC(__backtrace)
102ENDPROC(c_backtrace)
103
104		.pushsection __ex_table,"a"
105		.align	3
106		.long	1001b, 1006b
107		.long	1002b, 1006b
108		.long	1003b, 1006b
109		.long	1004b, 1006b
110		.popsection
111
112#define instr v4
113#define reg   v5
114#define stack v6
115
116.Ldumpstm:	stm.w	(instr, reg, stack, v7, lr), [sp-]
117		mov	stack, r0
118		mov	instr, r1
119		mov	reg, #14
120		mov	v7, #0
1211:		mov	r3, #1
122		csub.a	reg, #8
123		bne	201f
124		sub	reg, reg, #3
125201:
126		cand.a	instr, r3 << reg
127		beq	2f
128		add	v7, v7, #1
129		cxor.a	v7, #6
130		cmoveq	v7, #1
131		cmoveq	r1, #'\n'
132		cmovne	r1, #' '
133		ldw.w	r3, [stack]+, #-4
134		mov	r2, reg
135		csub.a	r2, #8
136		bsl	201f
137		sub	r2, r2, #3
138201:
139		cand.a	instr, #0x40		@ if H is 1, high 16 regs
140		beq	201f
141		add	r2, r2, #0x10		@ so r2 need add 16
142201:
143		adr	r0, .Lfp
144		b.l	printk
1452:		sub.a	reg, reg, #1
146		bns	1b
147		cxor.a	v7, #0
148		beq	201f
149		adr	r0, .Lcr
150		b.l	printk
151201:		ldm.w	(instr, reg, stack, v7, pc), [sp]+
152
153.Lfp:		.asciz	"%cr%d:%08x"
154.Lcr:		.asciz	"\n"
155.Lbad:		.asciz	"Backtrace aborted due to bad frame pointer <%p>\n"
156		.align
157.Ldsi:		.word	0x92eec000 >> 14	@ stm.w sp, (... fp, ip, lr, pc)
158		.word	0x92e10000 >> 14	@ stm.w sp, ()
159
160#endif