stacktrace.c

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/*
 * Stack trace utility
 *
 * Copyright 2008 Christoph Hellwig, IBM Corp.
 *
 *
 *      This program is free software; you can redistribute it and/or
 *      modify it under the terms of the GNU General Public License
 *      as published by the Free Software Foundation; either version
 *      2 of the License, or (at your option) any later version.
 */

#include <linux/export.h>
#include <linux/sched.h>
#include <linux/stacktrace.h>
#include <asm/ptrace.h>
#include <asm/processor.h>

/*
 * Save stack-backtrace addresses into a stack_trace buffer.
 */
static void save_context_stack(struct stack_trace *trace, unsigned long sp,
            struct task_struct *tsk, int savesched)
{
    for (;;) {
        unsigned long *stack = (unsigned long *) sp;
        unsigned long newsp, ip;

        if (!validate_sp(sp, tsk, STACK_FRAME_OVERHEAD))
            return;

        newsp = stack[0];
        ip = stack[STACK_FRAME_LR_SAVE];

        if (savesched || !in_sched_functions(ip)) {
            if (!trace->skip)
                trace->entries[trace->nr_entries++] = ip;
            else
                trace->skip--;
        }

        if (trace->nr_entries >= trace->max_entries)
            return;

        sp = newsp;
    }
}

void save_stack_trace(struct stack_trace *trace)
{
    unsigned long sp;

    asm("mr %0,1" : "=r" (sp));

    save_context_stack(trace, sp, current, 1);
}
EXPORT_SYMBOL_GPL(save_stack_trace);

void save_stack_trace_tsk(struct task_struct *tsk, struct stack_trace *trace)
{
    save_context_stack(trace, tsk->thread.ksp, tsk, 0);
}
EXPORT_SYMBOL_GPL(save_stack_trace_tsk);