pmu.cpp

/*
 * Copyright (c) 2017-2019 ARM Limited.
 *
 * SPDX-License-Identifier: MIT
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to
 * deal in the Software without restriction, including without limitation the
 * rights to use, copy, modify, merge, publish, distribute, sublicense, and/or
 * sell copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in all
 * copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 * SOFTWARE.
 */

#include "pmu.h"

#include <asm/unistd.h>
#include <cstring>
#include <stdexcept>
#include <sys/ioctl.h>

namespace vkb
{
PMU::PMU() :
    _perf_config()
{
	_perf_config.type = PERF_TYPE_HARDWARE;
	_perf_config.size = sizeof(perf_event_attr);

	// Start disabled
	_perf_config.disabled = 1;
	// The inherit bit specifies that this counter should count events of child
	// tasks as well as the task specified
	_perf_config.inherit = 1;
	// Enables saving of event counts on context switch for inherited tasks
	_perf_config.inherit_stat = 1;
}

PMU::PMU(uint64_t config) :
    PMU()
{
	open(config);
}

PMU::~PMU()
{
	close();
}

void PMU::open(uint64_t config)
{
	_perf_config.config = config;
	open(_perf_config);
}

void PMU::open(const perf_event_attr &perf_config)
{
	// Measure this process/thread (+ children) on any CPU
	_fd = syscall(__NR_perf_event_open, &perf_config, 0, -1, -1, 0);

	if (_fd < 0)
	{
		throw std::runtime_error("perf_event_open failed");
	}

	const int result = ioctl(_fd, PERF_EVENT_IOC_ENABLE, 0);
	if (result == -1)
	{
		throw std::runtime_error("Failed to enable PMU counter: " + std::to_string(errno));
	}
}

void PMU::close()
{
	if (_fd != -1)
	{
		::close(_fd);
		_fd = -1;
	}
}

void PMU::reset()
{
	const int result = ioctl(_fd, PERF_EVENT_IOC_RESET, 0);
	if (result == -1)
	{
		throw std::runtime_error("Failed to reset PMU counter: " + std::to_string(errno));
	}
}
}        // namespace vkb