stacktrace.c

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/*
 * Stack trace management functions
 *
 * Copyright (C) 2007 Atmel Corporation
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 */
#include <linux/sched.h>
#include <linux/stacktrace.h>
#include <linux/thread_info.h>
#include <linux/module.h>

register unsigned long current_frame_pointer asm("r7");

struct stackframe {
    unsigned long lr;
    unsigned long fp;
};

/*
 * Save stack-backtrace addresses into a stack_trace buffer.
 */
void save_stack_trace(struct stack_trace *trace)
{
    unsigned long low, high;
    unsigned long fp;
    struct stackframe *frame;
    int skip = trace->skip;

    low = (unsigned long)task_stack_page(current);
    high = low + THREAD_SIZE;
    fp = current_frame_pointer;

    while (fp >= low && fp <= (high - 8)) {
        frame = (struct stackframe *)fp;

        if (skip) {
            skip--;
        } else {
            trace->entries[trace->nr_entries++] = frame->lr;
            if (trace->nr_entries >= trace->max_entries)
                break;
        }

        /*
         * The next frame must be at a higher address than the
         * current frame.
         */
        low = fp + 8;
        fp = frame->fp;
    }
}
EXPORT_SYMBOL_GPL(save_stack_trace);