| 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 |