arch/arm/kernel/return_address.c

   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 int save_return_addr(struct stackframe *frame, void *d)
  20 {
  21         struct return_address_data *data = d;
  22
  23         if (!data->level) {
  24                 data->addr = (void *)frame->pc;
  25
  26                 return 1;
  27         } else {
  28                 --data->level;
  29                 return 0;
  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         frame.pc = (unsigned long)return_address;
  45
  46         walk_stackframe(&frame, save_return_addr, &data);
  47
  48         if (!data.level)
  49                 return data.addr;
  50         else
  51                 return NULL;
  52 }
  53
  54 EXPORT_SYMBOL_GPL(return_address);