LXR linux/arch/avr32/kernel/stacktrace.c

   1/*
   2 * Stack trace management functions
   3 *
   4 * Copyright (C) 2007 Atmel Corporation
   5 *
   6 * This program is free software; you can redistribute it and/or modify
   7 * it under the terms of the GNU General Public License version 2 as
   8 * published by the Free Software Foundation.
   9 */
  10#include <linux/sched.h>
  11#include <linux/stacktrace.h>
  12#include <linux/thread_info.h>
  13#include <linux/module.h>
  14
  15register unsigned long current_frame_pointer asm("r7");
  16
  17struct stackframe {
  18        unsigned long lr;
  19        unsigned long fp;
  20};
  21
  22/*
  23 * Save stack-backtrace addresses into a stack_trace buffer.
  24 */
  25void save_stack_trace(struct stack_trace *trace)
  26{
  27        unsigned long low, high;
  28        unsigned long fp;
  29        struct stackframe *frame;
  30        int skip = trace->skip;
  31
  32        low = (unsigned long)task_stack_page(current);
  33        high = low + THREAD_SIZE;
  34        fp = current_frame_pointer;
  35
  36        while (fp >= low && fp <= (high - 8)) {
  37                frame = (struct stackframe *)fp;
  38
  39                if (skip) {
  40                        skip--;
  41                } else {
  42                        trace->entries[trace->nr_entries++] = frame->lr;
  43                        if (trace->nr_entries >= trace->max_entries)
  44                                break;
  45                }
  46
  47                /*
  48                 * The next frame must be at a higher address than the
  49                 * current frame.
  50                 */
  51                low = fp + 8;
  52                fp = frame->fp;
  53        }
  54}
  55EXPORT_SYMBOL_GPL(save_stack_trace);
  56