arch/hexagon/kernel/stacktrace.c

   1 /*
   2  * Stacktrace support for Hexagon
   3  *
   4  * Copyright (c) 2010-2011, The Linux Foundation. All rights reserved.
   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 and
   8  * only version 2 as published by the Free Software Foundation.
   9  *
  10  * This program is distributed in the hope that it will be useful,
  11  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  12  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  13  * GNU General Public License for more details.
  14  *
  15  * You should have received a copy of the GNU General Public License
  16  * along with this program; if not, write to the Free Software
  17  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
  18  * 02110-1301, USA.
  19  */
  20
  21 #include <linux/sched.h>
  22 #include <linux/stacktrace.h>
  23 #include <linux/thread_info.h>
  24 #include <linux/module.h>
  25
  26 register unsigned long current_frame_pointer asm("r30");
  27
  28 struct stackframe {
  29         unsigned long fp;
  30         unsigned long rets;
  31 };
  32
  33 /*
  34  * Save stack-backtrace addresses into a stack_trace buffer.
  35  */
  36 void save_stack_trace(struct stack_trace *trace)
  37 {
  38         unsigned long low, high;
  39         unsigned long fp;
  40         struct stackframe *frame;
  41         int skip = trace->skip;
  42
  43         low = (unsigned long)task_stack_page(current);
  44         high = low + THREAD_SIZE;
  45         fp = current_frame_pointer;
  46
  47         while (fp >= low && fp <= (high - sizeof(*frame))) {
  48                 frame = (struct stackframe *)fp;
  49
  50                 if (skip) {
  51                         skip--;
  52                 } else {
  53                         trace->entries[trace->nr_entries++] = frame->rets;
  54                         if (trace->nr_entries >= trace->max_entries)
  55                                 break;
  56                 }
  57
  58                 /*
  59                  * The next frame must be at a higher address than the
  60                  * current frame.
  61                  */
  62                 low = fp + sizeof(*frame);
  63                 fp = frame->fp;
  64         }
  65 }
  66 EXPORT_SYMBOL_GPL(save_stack_trace);