LXR linux/arch/arm/kernel/return

   1/*
   2 * arch/arm/kernel/return_address.c
   3 *
   4 * Copyright (C) 2009 Uwe Kleine-Koenig <u.kleine-koenig@pengutronix.de>
   5 * for Pengutronix
   6 *
   7 * This program is free software; you can redistribute it and/or modify it
   8 * under the terms of the GNU General Public License version 2 as published by
   9 * the Free Software Foundation.
  10 */
  11#include <linux/module.h>
  12
  13#if defined(CONFIG_FRAME_POINTER) && !defined(CONFIG_ARM_UNWIND)
  14#include <linux/sched.h>
  15
  16#include <asm/stacktrace.h>
  17
  18struct return_address_data {
  19        unsigned int level;
  20        void *addr;
  21};
  22
  23static int save_return_addr(struct stackframe *frame, void *d)
  24{
  25        struct return_address_data *data = d;
  26
  27        if (!data->level) {
  28                data->addr = (void *)frame->lr;
  29
  30                return 1;
  31        } else {
  32                --data->level;
  33                return 0;
  34        }
  35}
  36
  37void *return_address(unsigned int level)
  38{
  39        struct return_address_data data;
  40        struct stackframe frame;
  41        register unsigned long current_sp asm ("sp");
  42
  43        data.level = level + 1;
  44
  45        frame.fp = (unsigned long)__builtin_frame_address(0);
  46        frame.sp = current_sp;
  47        frame.lr = (unsigned long)__builtin_return_address(0);
  48        frame.pc = (unsigned long)return_address;
  49
  50        walk_stackframe(&frame, save_return_addr, &data);
  51
  52        if (!data.level)
  53                return data.addr;
  54        else
  55                return NULL;
  56}
  57
  58#else /* if defined(CONFIG_FRAME_POINTER) && !defined(CONFIG_ARM_UNWIND) */
  59
  60#if defined(CONFIG_ARM_UNWIND)
  61#warning "TODO: return_address should use unwind tables"
  62#endif
  63
  64void *return_address(unsigned int level)
  65{
  66        return NULL;
  67}
  68
  69#endif /* if defined(CONFIG_FRAME_POINTER) && !defined(CONFIG_ARM_UNWIND) / else */
  70
  71EXPORT_SYMBOL_GPL(return_address);
  72