arch/i386/oprofile/nmi_timer_int.c

   1 /**
   2  * @file nmi_timer_int.c
   3  *
   4  * @remark Copyright 2003 OProfile authors
   5  * @remark Read the file COPYING
   6  *
   7  * @author Zwane Mwaikambo <zwane@linuxpower.ca>
   8  */
   9
  10 #include <linux/init.h>
  11 #include <linux/smp.h>
  12 #include <linux/errno.h>
  13 #include <linux/oprofile.h>
  14 #include <linux/rcupdate.h>
  15
  16
  17 #include <asm/nmi.h>
  18 #include <asm/apic.h>
  19 #include <asm/ptrace.h>
  20 #include <asm/kdebug.h>
  21
  22 static int profile_timer_exceptions_notify(struct notifier_block *self,
  23                                            unsigned long val, void *data)
  24 {
  25         struct die_args *args = (struct die_args *)data;
  26         int ret = NOTIFY_DONE;
  27
  28         switch(val) {
  29         case DIE_NMI:
  30                 oprofile_add_sample(args->regs, 0);
  31                 ret = NOTIFY_STOP;
  32                 break;
  33         default:
  34                 break;
  35         }
  36         return ret;
  37 }
  38
  39 static struct notifier_block profile_timer_exceptions_nb = {
  40         .notifier_call = profile_timer_exceptions_notify,
  41         .next = NULL,
  42         .priority = 0
  43 };
  44
  45 static int timer_start(void)
  46 {
  47         if (register_die_notifier(&profile_timer_exceptions_nb))
  48                 return 1;
  49         return 0;
  50 }
  51
  52
  53 static void timer_stop(void)
  54 {
  55         unregister_die_notifier(&profile_timer_exceptions_nb);
  56         synchronize_sched();  /* Allow already-started NMIs to complete. */
  57 }
  58
  59
  60 int __init op_nmi_timer_init(struct oprofile_operations * ops)
  61 {
  62         if ((nmi_watchdog != NMI_IO_APIC) || (atomic_read(&nmi_active) <= 0))
  63                 return -ENODEV;
  64
  65         ops->start = timer_start;
  66         ops->stop = timer_stop;
  67         ops->cpu_type = "timer";
  68         printk(KERN_INFO "oprofile: using NMI timer interrupt.\n");
  69         return 0;
  70 }