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nmi_timer_int.c

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/**
 * @file nmi_timer_int.c
 *
 * @remark Copyright 2003 OProfile authors
 * @remark Read the file COPYING
 *
 * @author Zwane Mwaikambo <zwane@linuxpower.ca>
 */

#include <linux/init.h>
#include <linux/smp.h>
#include <linux/errno.h>
#include <linux/oprofile.h>
#include <linux/rcupdate.h>
#include <linux/kdebug.h>

#include <asm/nmi.h>
#include <asm/apic.h>
#include <asm/ptrace.h>
 
static int profile_timer_exceptions_notify(struct notifier_block *self,
                                 unsigned long val, void *data)
{
      struct die_args *args = (struct die_args *)data;
      int ret = NOTIFY_DONE;

      switch(val) {
      case DIE_NMI:
            oprofile_add_sample(args->regs, 0);
            ret = NOTIFY_STOP;
            break;
      default:
            break;
      }
      return ret;
}

static struct notifier_block profile_timer_exceptions_nb = {
      .notifier_call = profile_timer_exceptions_notify,
      .next = NULL,
      .priority = 0
};

static int timer_start(void)
{
      if (register_die_notifier(&profile_timer_exceptions_nb))
            return 1;
      return 0;
}


static void timer_stop(void)
{
      unregister_die_notifier(&profile_timer_exceptions_nb);
      synchronize_sched();  /* Allow already-started NMIs to complete. */
}


int __init op_nmi_timer_init(struct oprofile_operations * ops)
{
      if ((nmi_watchdog != NMI_IO_APIC) || (atomic_read(&nmi_active) <= 0))
            return -ENODEV;

      ops->start = timer_start;
      ops->stop = timer_stop;
      ops->cpu_type = "timer";
      printk(KERN_INFO "oprofile: using NMI timer interrupt.\n");
      return 0;
}

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