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 | |
14 | struct return_address_data { |
15 | unsigned int level; |
16 | void *addr; |
17 | }; |
18 | |
19 | static 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 | |
33 | void *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 | here: |
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 | |
60 | EXPORT_SYMBOL_GPL(return_address); |
61 |