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