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 
return_address(unsigned int depth)14 void *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 
return_address(unsigned int depth)49 void *return_address(unsigned int depth)
50 {
51 	return NULL;
52 }
53 
54 #endif
55 
56 EXPORT_SYMBOL_GPL(return_address);
57