arch/x86/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 #include <linux/kdebug.h>
  16
  17 #include <asm/nmi.h>
  18 #include <asm/apic.h>
  19 #include <asm/ptrace.h>
  20
  21 static int profile_timer_exceptions_notify(struct notifier_block *self,
  22                                            unsigned long val, void *data)
  23 {
  24         struct die_args *args = (struct die_args *)data;
  25         int ret = NOTIFY_DONE;
  26
  27         switch (val) {
  28         case DIE_NMI:
  29                 oprofile_add_sample(args->regs, 0);
  30                 ret = NOTIFY_STOP;
  31                 break;
  32         default:
  33                 break;
  34         }
  35         return ret;
  36 }
  37
  38 static struct notifier_block profile_timer_exceptions_nb = {
  39         .notifier_call = profile_timer_exceptions_notify,
  40         .next = NULL,
  41         .priority = 0
  42 };
  43
  44 static int timer_start(void)
  45 {
  46         if (register_die_notifier(&profile_timer_exceptions_nb))
  47                 return 1;
  48         return 0;
  49 }
  50
  51
  52 static void timer_stop(void)
  53 {
  54         unregister_die_notifier(&profile_timer_exceptions_nb);
  55         synchronize_sched();  /* Allow already-started NMIs to complete. */
  56 }
  57
  58
  59 int __init op_nmi_timer_init(struct oprofile_operations *ops)
  60 {
  61         if ((nmi_watchdog != NMI_IO_APIC) || (atomic_read(&nmi_active) <= 0))
  62                 return -ENODEV;
  63
  64         ops->start = timer_start;
  65         ops->stop = timer_stop;
  66         ops->cpu_type = "timer";
  67         printk(KERN_INFO "oprofile: using NMI timer interrupt.\n");
  68         return 0;
  69 }