oprof.c

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#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/init.h>
#include <linux/oprofile.h>
#include <linux/moduleparam.h>
#include <linux/workqueue.h>
#include <linux/time.h>
#include <linux/mutex.h>

#include "oprof.h"
#include "event_buffer.h"
#include "cpu_buffer.h"
#include "buffer_sync.h"
#include "oprofile_stats.h"

struct oprofile_operations oprofile_ops;

unsigned long oprofile_started;
unsigned long oprofile_backtrace_depth;
static unsigned long is_setup;
static DEFINE_MUTEX(start_mutex);

/* timer
   0 - use performance monitoring hardware if available
   1 - use the timer int mechanism regardless
 */
static int timer = 0;

int oprofile_setup(void)
{
    int err;

    mutex_lock(&start_mutex);

    if ((err = alloc_cpu_buffers()))
        goto out;

    if ((err = alloc_event_buffer()))
        goto out1;

    if (oprofile_ops.setup && (err = oprofile_ops.setup()))
        goto out2;

    /* Note even though this starts part of the
     * profiling overhead, it's necessary to prevent
     * us missing task deaths and eventually oopsing
     * when trying to process the event buffer.
     */
    if (oprofile_ops.sync_start) {
        int sync_ret = oprofile_ops.sync_start();
        switch (sync_ret) {
        case 0:
            goto post_sync;
        case 1:
            goto do_generic;
        case -1:
            goto out3;
        default:
            goto out3;
        }
    }
do_generic:
    if ((err = sync_start()))
        goto out3;

post_sync:
    is_setup = 1;
    mutex_unlock(&start_mutex);
    return 0;

out3:
    if (oprofile_ops.shutdown)
        oprofile_ops.shutdown();
out2:
    free_event_buffer();
out1:
    free_cpu_buffers();
out:
    mutex_unlock(&start_mutex);
    return err;
}

#ifdef CONFIG_OPROFILE_EVENT_MULTIPLEX

static void switch_worker(struct work_struct *work);
static DECLARE_DELAYED_WORK(switch_work, switch_worker);

static void start_switch_worker(void)
{
    if (oprofile_ops.switch_events)
        schedule_delayed_work(&switch_work, oprofile_time_slice);
}

static void stop_switch_worker(void)
{
    cancel_delayed_work_sync(&switch_work);
}

static void switch_worker(struct work_struct *work)
{
    if (oprofile_ops.switch_events())
        return;

    atomic_inc(&oprofile_stats.multiplex_counter);
    start_switch_worker();
}

/* User inputs in ms, converts to jiffies */
int oprofile_set_timeout(unsigned long val_msec)
{
    int err = 0;
    unsigned long time_slice;

    mutex_lock(&start_mutex);

    if (oprofile_started) {
        err = -EBUSY;
        goto out;
    }

    if (!oprofile_ops.switch_events) {
        err = -EINVAL;
        goto out;
    }

    time_slice = msecs_to_jiffies(val_msec);
    if (time_slice == MAX_JIFFY_OFFSET) {
        err = -EINVAL;
        goto out;
    }

    oprofile_time_slice = time_slice;

out:
    mutex_unlock(&start_mutex);
    return err;

}

#else

static inline void start_switch_worker(void) { }
static inline void stop_switch_worker(void) { }

#endif

/* Actually start profiling (echo 1>/dev/oprofile/enable) */
int oprofile_start(void)
{
    int err = -EINVAL;

    mutex_lock(&start_mutex);

    if (!is_setup)
        goto out;

    err = 0;

    if (oprofile_started)
        goto out;

    oprofile_reset_stats();

    if ((err = oprofile_ops.start()))
        goto out;

    start_switch_worker();

    oprofile_started = 1;
out:
    mutex_unlock(&start_mutex);
    return err;
}


/* echo 0>/dev/oprofile/enable */
void oprofile_stop(void)
{
    mutex_lock(&start_mutex);
    if (!oprofile_started)
        goto out;
    oprofile_ops.stop();
    oprofile_started = 0;

    stop_switch_worker();

    /* wake up the daemon to read what remains */
    wake_up_buffer_waiter();
out:
    mutex_unlock(&start_mutex);
}


void oprofile_shutdown(void)
{
    mutex_lock(&start_mutex);
    if (oprofile_ops.sync_stop) {
        int sync_ret = oprofile_ops.sync_stop();
        switch (sync_ret) {
        case 0:
            goto post_sync;
        case 1:
            goto do_generic;
        default:
            goto post_sync;
        }
    }
do_generic:
    sync_stop();
post_sync:
    if (oprofile_ops.shutdown)
        oprofile_ops.shutdown();
    is_setup = 0;
    free_event_buffer();
    free_cpu_buffers();
    mutex_unlock(&start_mutex);
}

int oprofile_set_ulong(unsigned long *addr, unsigned long val)
{
    int err = -EBUSY;

    mutex_lock(&start_mutex);
    if (!oprofile_started) {
        *addr = val;
        err = 0;
    }
    mutex_unlock(&start_mutex);

    return err;
}

static int timer_mode;

static int __init oprofile_init(void)
{
    int err;

    /* always init architecture to setup backtrace support */
    timer_mode = 0;
    err = oprofile_arch_init(&oprofile_ops);
    if (!err) {
        if (!timer && !oprofilefs_register())
            return 0;
        oprofile_arch_exit();
    }

    /* setup timer mode: */
    timer_mode = 1;
    /* no nmi timer mode if oprofile.timer is set */
    if (timer || op_nmi_timer_init(&oprofile_ops)) {
        err = oprofile_timer_init(&oprofile_ops);
        if (err)
            return err;
    }

    return oprofilefs_register();
}


static void __exit oprofile_exit(void)
{
    oprofilefs_unregister();
    if (!timer_mode)
        oprofile_arch_exit();
}


module_init(oprofile_init);
module_exit(oprofile_exit);

module_param_named(timer, timer, int, 0644);
MODULE_PARM_DESC(timer, "force use of timer interrupt");

MODULE_LICENSE("GPL");
MODULE_AUTHOR("John Levon <[email protected]>");
MODULE_DESCRIPTION("OProfile system profiler");