arm64/kernel/return_address.c

0001 // SPDX-License-Identifier: GPL-2.0-only
0002 /*
0003  * arch/arm64/kernel/return_address.c
0004  *
0005  * Copyright (C) 2013 Linaro Limited
0006  * Author: AKASHI Takahiro <takahiro.akashi@linaro.org>
0007  */
0008
0009 #include <linux/export.h>
0010 #include <linux/ftrace.h>
0011 #include <linux/kprobes.h>
0012 #include <linux/stacktrace.h>
0013
0014 #include <asm/stack_pointer.h>
0015
0016 struct return_address_data {
0017     unsigned int level;
0018     void *addr;
0019 };
0020
0021 static bool save_return_addr(void *d, unsigned long pc)
0022 {
0023     struct return_address_data *data = d;
0024
0025     if (!data->level) {
0026         data->addr = (void *)pc;
0027         return false;
0028     } else {
0029         --data->level;
0030         return true;
0031     }
0032 }
0033 NOKPROBE_SYMBOL(save_return_addr);
0034
0035 void *return_address(unsigned int level)
0036 {
0037     struct return_address_data data;
0038
0039     data.level = level + 2;
0040     data.addr = NULL;
0041
0042     arch_stack_walk(save_return_addr, &data, current, NULL);
0043
0044     if (!data.level)
0045         return data.addr;
0046     else
0047         return NULL;
0048 }
0049 EXPORT_SYMBOL_GPL(return_address);
0050 NOKPROBE_SYMBOL(return_address);