arch/arm64/kernel/return_address.c

   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(save_return_addr, &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);