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/sched/task_stack.h>
  23#include <linux/stacktrace.h>
  24#include <linux/thread_info.h>
  25#include <linux/module.h>
  26
  27register unsigned long current_frame_pointer asm("r30");
  28
  29struct stackframe {
  30        unsigned long fp;
  31        unsigned long rets;
  32};
  33
  34/*
  35 * Save stack-backtrace addresses into a stack_trace buffer.
  36 */
  37void save_stack_trace(struct stack_trace *trace)
  38{
  39        unsigned long low, high;
  40        unsigned long fp;
  41        struct stackframe *frame;
  42        int skip = trace->skip;
  43
  44        low = (unsigned long)task_stack_page(current);
  45        high = low + THREAD_SIZE;
  46        fp = current_frame_pointer;
  47
  48        while (fp >= low && fp <= (high - sizeof(*frame))) {
  49                frame = (struct stackframe *)fp;
  50
  51                if (skip) {
  52                        skip--;
  53                } else {
  54                        trace->entries[trace->nr_entries++] = frame->rets;
  55                        if (trace->nr_entries >= trace->max_entries)
  56                                break;
  57                }
  58
  59                /*
  60                 * The next frame must be at a higher address than the
  61                 * current frame.
  62                 */
  63                low = fp + sizeof(*frame);
  64                fp = frame->fp;
  65        }
  66}
  67EXPORT_SYMBOL_GPL(save_stack_trace);
  68