1// SPDX-License-Identifier: GPL-2.0-only
 2/*
 3 * arch/arm64/kernel/return_address.c
 4 *
 5 * Copyright (C) 2013 Linaro Limited
 6 * Author: AKASHI Takahiro <takahiro.akashi@linaro.org>
 7 */
 8
 9#include <linux/export.h>
10#include <linux/ftrace.h>
11#include <linux/kprobes.h>
12#include <linux/stacktrace.h>
13
14#include <asm/stack_pointer.h>
15
16struct return_address_data {
17	unsigned int level;
18	void *addr;
19};
20
21static bool save_return_addr(void *d, unsigned long pc)
22{
23	struct return_address_data *data = d;
24
25	if (!data->level) {
26		data->addr = (void *)pc;
27		return false;
28	} else {
29		--data->level;
30		return true;
31	}
32}
33NOKPROBE_SYMBOL(save_return_addr);
34
35void *return_address(unsigned int level)
36{
37	struct return_address_data data;
38
39	data.level = level + 2;
40	data.addr = NULL;
41
42	arch_stack_walk(save_return_addr, &data, current, NULL);
43
44	if (!data.level)
45		return data.addr;
46	else
47		return NULL;
48}
49EXPORT_SYMBOL_GPL(return_address);
50NOKPROBE_SYMBOL(return_address);