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
  14 register unsigned long current_frame_pointer asm("r7");
  15
  16 struct stackframe {
  17         unsigned long lr;
  18         unsigned long fp;
  19 };
  20
  21 /*
  22  * Save stack-backtrace addresses into a stack_trace buffer.
  23  */
  24 void save_stack_trace(struct stack_trace *trace)
  25 {
  26         unsigned long low, high;
  27         unsigned long fp;
  28         struct stackframe *frame;
  29         int skip = trace->skip;
  30
  31         low = (unsigned long)task_stack_page(current);
  32         high = low + THREAD_SIZE;
  33         fp = current_frame_pointer;
  34
  35         while (fp >= low && fp <= (high - 8)) {
  36                 frame = (struct stackframe *)fp;
  37
  38                 if (skip) {
  39                         skip--;
  40                 } else {
  41                         trace->entries[trace->nr_entries++] = frame->lr;
  42                         if (trace->nr_entries >= trace->max_entries)
  43                                 break;
  44                 }
  45
  46                 /*
  47                  * The next frame must be at a higher address than the
  48                  * current frame.
  49                  */
  50                 low = fp + 8;
  51                 fp = frame->fp;
  52         }
  53 }