| 1 | // SPDX-License-Identifier: GPL-2.0-only |
|---|---|
| 2 | /* |
| 3 | * arch/arm64/kernel/return_address.c |
| 4 | * |
| 5 | * Copyright (C) 2013 Linaro Limited |
| 6 | * Author: AKASHI Takahiro <takahiro.akashi@linaro.org> |
| 7 | */ |
| 8 | |
| 9 | #include <linux/export.h> |
| 10 | #include <linux/ftrace.h> |
| 11 | #include <linux/kprobes.h> |
| 12 | #include <linux/stacktrace.h> |
| 13 | |
| 14 | #include <asm/stack_pointer.h> |
| 15 | |
| 16 | struct return_address_data { |
| 17 | unsigned int level; |
| 18 | void *addr; |
| 19 | }; |
| 20 | |
| 21 | static bool save_return_addr(void *d, unsigned long pc) |
| 22 | { |
| 23 | struct return_address_data *data = d; |
| 24 | |
| 25 | if (!data->level) { |
| 26 | data->addr = (void *)pc; |
| 27 | return false; |
| 28 | } else { |
| 29 | --data->level; |
| 30 | return true; |
| 31 | } |
| 32 | } |
| 33 | NOKPROBE_SYMBOL(save_return_addr); |
| 34 | |
| 35 | void *return_address(unsigned int level) |
| 36 | { |
| 37 | struct return_address_data data; |
| 38 | |
| 39 | data.level = level + 2; |
| 40 | data.addr = NULL; |
| 41 | |
| 42 | arch_stack_walk(consume_entry: save_return_addr, cookie: &data, current, NULL); |
| 43 | |
| 44 | if (!data.level) |
| 45 | return data.addr; |
| 46 | else |
| 47 | return NULL; |
| 48 | } |
| 49 | EXPORT_SYMBOL_GPL(return_address); |
| 50 | NOKPROBE_SYMBOL(return_address); |
| 51 |