LXR linux/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
  26register unsigned long current_frame_pointer asm("r30");
  27
  28struct stackframe {
  29        unsigned long fp;
  30        unsigned long rets;
  31};
  32
  33/*
  34 * Save stack-backtrace addresses into a stack_trace buffer.
  35 */
  36void 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}
  66EXPORT_SYMBOL_GPL(save_stack_trace);
  67