/* -*- linux-c -*- 
 * Perf Functions
 * Copyright (C) 2006 Red Hat Inc.
 * Copyright (C) 2010 Red Hat Inc.
 *
 * This file is part of systemtap, and is free software.  You can
 * redistribute it and/or modify it under the terms of the GNU General
 * Public License (GPL); either version 2, or (at your option) any
 * later version.
 */

#ifndef _PERF_C_
#define _PERF_C_

#include <linux/perf_event.h>

#include "perf.h"

/** @file perf.c
 * @brief Implements performance monitoring hardware support
 */

/** Initialize performance sampling
 * Call this during probe initialization to set up performance event sampling
 *
 * @param attr description of event to sample
 * @param callback function to call when perf event overflows
 */
static Perf _stp_perf_init (struct perf_event_attr *attr,
			    perf_overflow_handler_t callback)
{
	int cpu;
	Perf pe;

	pe = (Perf) _stp_kmalloc (sizeof(struct _Perf));
	if (pe == NULL)
		return NULL;
	pe->callback = callback;

	/* allocate space for the event descriptor for each cpu */
	pe->pd = (struct perf_event **)
		_stp_alloc_percpu (sizeof(struct perf_event *));
	if (pe->pd == NULL)
		goto exit1;

	/* initialize event on each processor */
	stp_for_each_cpu(cpu) {
		struct perf_event **event = per_cpu_ptr (pe->pd, cpu);
		*event = perf_event_create_kernel_counter(attr, cpu, -1,
							  callback);

		if (IS_ERR(*event)) {
			*event = NULL;
			goto exit2;
		}
	}
	return pe;

exit2:
	stp_for_each_cpu(cpu) {
		struct perf_event **event = per_cpu_ptr (pe->pd, cpu);
		if (*event) perf_event_release_kernel(*event);
	}
	_stp_free_percpu(pe->pd);
exit1:
	_stp_kfree(pe);
	return NULL;
}

/** Delete performance event.
 * Call this to shutdown performance event sampling
 *
 * @param pe
 */
static void _stp_perf_del (Perf pe)
{
	if (pe) {
		int cpu;
		/* shut down performance event sampling */
		stp_for_each_cpu(cpu) {
			struct perf_event **event = per_cpu_ptr (pe->pd, cpu);
			if (*event) {
				perf_event_release_kernel(*event);
			}
		}
		_stp_free_percpu (pe->pd);
		_stp_kfree (pe);
	}
}

#endif /* _PERF_C_ */