release/src-rt-6.x.4708/linux/linux-2.6.36/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
  15 register unsigned long current_frame_pointer asm("r7");
  16
  17 struct stackframe {
  18         unsigned long lr;
  19         unsigned long fp;
  20 };
  21
  22 /*
  23  * Save stack-backtrace addresses into a stack_trace buffer.
  24  */
  25 void 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 }
  55 EXPORT_SYMBOL_GPL(save_stack_trace);