1// SPDX-License-Identifier: GPL-2.0
2/*
3 * arch/sh/kernel/return_address.c
4 *
5 * Copyright (C) 2009  Matt Fleming
6 * Copyright (C) 2009  Paul Mundt
7 */
8#include <linux/kernel.h>
9#include <linux/module.h>
10#include <asm/dwarf.h>
11
12#ifdef CONFIG_DWARF_UNWINDER
13
14void *return_address(unsigned int depth)
15{
16	struct dwarf_frame *frame;
17	unsigned long ra;
18	int i;
19
20	for (i = 0, frame = NULL, ra = 0; i <= depth; i++) {
21		struct dwarf_frame *tmp;
22
23		tmp = dwarf_unwind_stack(ra, frame);
24		if (!tmp)
25			return NULL;
26
27		if (frame)
28			dwarf_free_frame(frame);
29
30		frame = tmp;
31
32		if (!frame || !frame->return_addr)
33			break;
34
35		ra = frame->return_addr;
36	}
37
38	/* Failed to unwind the stack to the specified depth. */
39	WARN_ON(i != depth + 1);
40
41	if (frame)
42		dwarf_free_frame(frame);
43
44	return (void *)ra;
45}
46
47#else
48
49void *return_address(unsigned int depth)
50{
51	return NULL;
52}
53
54#endif
55
56EXPORT_SYMBOL_GPL(return_address);
57