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 int save_return_addr(struct stackframe *frame, void *d)
20{
21	struct return_address_data *data = d;
22
23	if (!data->level) {
24		data->addr = (void *)frame->pc;
25
26		return 1;
27	} else {
28		--data->level;
29		return 0;
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);
44	frame.pc = (unsigned long)return_address;
 
 
 
 
 
 
45
46	walk_stackframe(&frame, save_return_addr, &data);
47
48	if (!data.level)
49		return data.addr;
50	else
51		return NULL;
52}
53
54EXPORT_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);