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/**
* @file nmi_timer_int.c
*
* @remark Copyright 2011 Advanced Micro Devices, Inc.
*
* @author Robert Richter <robert.richter@amd.com>
*/
#include <linux/init.h>
#include <linux/smp.h>
#include <linux/errno.h>
#include <linux/oprofile.h>
#include <linux/perf_event.h>
#ifdef CONFIG_OPROFILE_NMI_TIMER
static DEFINE_PER_CPU(struct perf_event *, nmi_timer_events);
static int ctr_running;
static struct perf_event_attr nmi_timer_attr = {
.type = PERF_TYPE_HARDWARE,
.config = PERF_COUNT_HW_CPU_CYCLES,
.size = sizeof(struct perf_event_attr),
.pinned = 1,
.disabled = 1,
};
static void nmi_timer_callback(struct perf_event *event,
struct perf_sample_data *data,
struct pt_regs *regs)
{
event->hw.interrupts = 0; /* don't throttle interrupts */
oprofile_add_sample(regs, 0);
}
static int nmi_timer_start_cpu(int cpu)
{
struct perf_event *event = per_cpu(nmi_timer_events, cpu);
if (!event) {
event = perf_event_create_kernel_counter(&nmi_timer_attr, cpu, NULL,
nmi_timer_callback, NULL);
if (IS_ERR(event))
return PTR_ERR(event);
per_cpu(nmi_timer_events, cpu) = event;
}
if (event && ctr_running)
perf_event_enable(event);
return 0;
}
static void nmi_timer_stop_cpu(int cpu)
{
struct perf_event *event = per_cpu(nmi_timer_events, cpu);
if (event && ctr_running)
perf_event_disable(event);
}
static int nmi_timer_cpu_notifier(struct notifier_block *b, unsigned long action,
void *data)
{
int cpu = (unsigned long)data;
switch (action) {
case CPU_DOWN_FAILED:
case CPU_ONLINE:
nmi_timer_start_cpu(cpu);
break;
case CPU_DOWN_PREPARE:
nmi_timer_stop_cpu(cpu);
break;
}
return NOTIFY_DONE;
}
static struct notifier_block nmi_timer_cpu_nb = {
.notifier_call = nmi_timer_cpu_notifier
};
static int nmi_timer_start(void)
{
int cpu;
get_online_cpus();
ctr_running = 1;
for_each_online_cpu(cpu)
nmi_timer_start_cpu(cpu);
put_online_cpus();
return 0;
}
static void nmi_timer_stop(void)
{
int cpu;
get_online_cpus();
for_each_online_cpu(cpu)
nmi_timer_stop_cpu(cpu);
ctr_running = 0;
put_online_cpus();
}
static void nmi_timer_shutdown(void)
{
struct perf_event *event;
int cpu;
get_online_cpus();
unregister_cpu_notifier(&nmi_timer_cpu_nb);
for_each_possible_cpu(cpu) {
event = per_cpu(nmi_timer_events, cpu);
if (!event)
continue;
perf_event_disable(event);
per_cpu(nmi_timer_events, cpu) = NULL;
perf_event_release_kernel(event);
}
put_online_cpus();
}
static int nmi_timer_setup(void)
{
int cpu, err;
u64 period;
/* clock cycles per tick: */
period = (u64)cpu_khz * 1000;
do_div(period, HZ);
nmi_timer_attr.sample_period = period;
get_online_cpus();
err = register_cpu_notifier(&nmi_timer_cpu_nb);
if (err)
goto out;
/* can't attach events to offline cpus: */
for_each_online_cpu(cpu) {
err = nmi_timer_start_cpu(cpu);
if (err)
break;
}
if (err)
nmi_timer_shutdown();
out:
put_online_cpus();
return err;
}
int __init op_nmi_timer_init(struct oprofile_operations *ops)
{
int err = 0;
err = nmi_timer_setup();
if (err)
return err;
nmi_timer_shutdown(); /* only check, don't alloc */
ops->create_files = NULL;
ops->setup = nmi_timer_setup;
ops->shutdown = nmi_timer_shutdown;
ops->start = nmi_timer_start;
ops->stop = nmi_timer_stop;
ops->cpu_type = "timer";
printk(KERN_INFO "oprofile: using NMI timer interrupt.\n");
return 0;
}
#endif
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