1/*
 2 * arch/arm/kernel/return_address.c
 3 *
 4 * Copyright (C) 2009 Uwe Kleine-Koenig <u.kleine-koenig@pengutronix.de>
 5 * for Pengutronix
 6 *
 7 * This program is free software; you can redistribute it and/or modify it
 8 * under the terms of the GNU General Public License version 2 as published by
 9 * the Free Software Foundation.
10 */
11#include <linux/export.h>
12#include <linux/ftrace.h>
13
14#if defined(CONFIG_FRAME_POINTER) && !defined(CONFIG_ARM_UNWIND)
15#include <linux/sched.h>
16
17#include <asm/stacktrace.h>
18
19struct return_address_data {
20	unsigned int level;
21	void *addr;
22};
23
24static int save_return_addr(struct stackframe *frame, void *d)
25{
26	struct return_address_data *data = d;
27
28	if (!data->level) {
29		data->addr = (void *)frame->pc;
30
31		return 1;
32	} else {
33		--data->level;
34		return 0;
35	}
36}
37
38void *return_address(unsigned int level)
39{
40	struct return_address_data data;
41	struct stackframe frame;
42
43	data.level = level + 2;
44	data.addr = NULL;
45
46	frame.fp = (unsigned long)__builtin_frame_address(0);
47	frame.sp = current_stack_pointer;
48	frame.lr = (unsigned long)__builtin_return_address(0);
49	frame.pc = (unsigned long)return_address;
 
 
 
 
 
 
50
51	walk_stackframe(&frame, save_return_addr, &data);
52
53	if (!data.level)
54		return data.addr;
55	else
56		return NULL;
57}
58
59#endif /* if defined(CONFIG_FRAME_POINTER) && !defined(CONFIG_ARM_UNWIND) */
60
61EXPORT_SYMBOL_GPL(return_address);

 1// SPDX-License-Identifier: GPL-2.0-only
 2/*
 3 * arch/arm/kernel/return_address.c
 4 *
 5 * Copyright (C) 2009 Uwe Kleine-Koenig <u.kleine-koenig@pengutronix.de>
 6 * for Pengutronix
 
 
 
 
 7 */
 8#include <linux/export.h>
 9#include <linux/ftrace.h>
 
 
10#include <linux/sched.h>
11
12#include <asm/stacktrace.h>
13
14struct return_address_data {
15	unsigned int level;
16	void *addr;
17};
18
19static bool save_return_addr(void *d, unsigned long pc)
20{
21	struct return_address_data *data = d;
22
23	if (!data->level) {
24		data->addr = (void *)pc;
25
26		return false;
27	} else {
28		--data->level;
29		return true;
30	}
31}
32
33void *return_address(unsigned int level)
34{
35	struct return_address_data data;
36	struct stackframe frame;
37
38	data.level = level + 2;
39	data.addr = NULL;
40
41	frame.fp = (unsigned long)__builtin_frame_address(0);
42	frame.sp = current_stack_pointer;
43	frame.lr = (unsigned long)__builtin_return_address(0);
44here:
45	frame.pc = (unsigned long)&&here;
46#ifdef CONFIG_KRETPROBES
47	frame.kr_cur = NULL;
48	frame.tsk = current;
49#endif
50	frame.ex_frame = false;
51
52	walk_stackframe(&frame, save_return_addr, &data);
53
54	if (!data.level)
55		return data.addr;
56	else
57		return NULL;
58}
 
 
59
60EXPORT_SYMBOL_GPL(return_address);