1/*
 2 * arch/arm/kernel/return_address.c
 3 *
 4 * Copyright (C) 2009 Uwe Kleine-Koenig <u.kleine-koenig@pengutronix.de>
 5 * for Pengutronix
 6 *
 7 * This program is free software; you can redistribute it and/or modify it
 8 * under the terms of the GNU General Public License version 2 as published by
 9 * the Free Software Foundation.
10 */
11#include <linux/export.h>
12#include <linux/ftrace.h>
13
14#if defined(CONFIG_FRAME_POINTER) && !defined(CONFIG_ARM_UNWIND)
15#include <linux/sched.h>
16
17#include <asm/stacktrace.h>
18
19struct return_address_data {
20	unsigned int level;
21	void *addr;
22};
23
24static int save_return_addr(struct stackframe *frame, void *d)
25{
26	struct return_address_data *data = d;
27
28	if (!data->level) {
29		data->addr = (void *)frame->lr;
30
31		return 1;
32	} else {
33		--data->level;
34		return 0;
35	}
36}
37
38void *return_address(unsigned int level)
39{
40	struct return_address_data data;
41	struct stackframe frame;
42	register unsigned long current_sp asm ("sp");
43
44	data.level = level + 1;
 
45
46	frame.fp = (unsigned long)__builtin_frame_address(0);
47	frame.sp = current_sp;
48	frame.lr = (unsigned long)__builtin_return_address(0);
49	frame.pc = (unsigned long)return_address;
50
51	walk_stackframe(&frame, save_return_addr, &data);
52
53	if (!data.level)
54		return data.addr;
55	else
56		return NULL;
57}
58
59#else /* if defined(CONFIG_FRAME_POINTER) && !defined(CONFIG_ARM_UNWIND) */
60
61#if defined(CONFIG_ARM_UNWIND)
62#warning "TODO: return_address should use unwind tables"
63#endif
64
65void *return_address(unsigned int level)
66{
67	return NULL;
68}
69
70#endif /* if defined(CONFIG_FRAME_POINTER) && !defined(CONFIG_ARM_UNWIND) / else */
71
72EXPORT_SYMBOL_GPL(return_address);

 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
11#if defined(CONFIG_FRAME_POINTER) && !defined(CONFIG_ARM_UNWIND)
12#include <linux/sched.h>
13
14#include <asm/stacktrace.h>
15
16struct return_address_data {
17	unsigned int level;
18	void *addr;
19};
20
21static int save_return_addr(struct stackframe *frame, void *d)
22{
23	struct return_address_data *data = d;
24
25	if (!data->level) {
26		data->addr = (void *)frame->pc;
27
28		return 1;
29	} else {
30		--data->level;
31		return 0;
32	}
33}
34
35void *return_address(unsigned int level)
36{
37	struct return_address_data data;
38	struct stackframe frame;
 
39
40	data.level = level + 2;
41	data.addr = NULL;
42
43	frame.fp = (unsigned long)__builtin_frame_address(0);
44	frame.sp = current_stack_pointer;
45	frame.lr = (unsigned long)__builtin_return_address(0);
46	frame.pc = (unsigned long)return_address;
47
48	walk_stackframe(&frame, save_return_addr, &data);
49
50	if (!data.level)
51		return data.addr;
52	else
53		return NULL;
54}
55
56#endif /* if defined(CONFIG_FRAME_POINTER) && !defined(CONFIG_ARM_UNWIND) */
 
 
 
 
 
 
 
 
 
 
 
57
58EXPORT_SYMBOL_GPL(return_address);