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);
61

source code of linux/arch/arm/kernel/return_address.c