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 
profile_timer_exceptions_notify(struct notifier_block * self,unsigned long val,void * data)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 = NMI_LOW_PRIOR,
42 };
43 
timer_start(void)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 
timer_stop(void)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 
op_nmi_timer_init(struct oprofile_operations * ops)59 int __init op_nmi_timer_init(struct oprofile_operations *ops)
60 {
61 	ops->start = timer_start;
62 	ops->stop = timer_stop;
63 	ops->cpu_type = "timer";
64 	printk(KERN_INFO "oprofile: using NMI timer interrupt.\n");
65 	return 0;
66 }
67