/*

 * notify_self.c - example of how you can use overflow notifications

 *

 * Copyright (c) 2009 Google, Inc

 * Contributed by Stephane Eranian <eranian@gmail.com>

 *

 * 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 <sys/types.h>

#include <inttypes.h>

#include <stdio.h>

#include <stdlib.h>

#include <errno.h>

#include <unistd.h>

#include <string.h>

#include <signal.h>

#include <fcntl.h>

#include <err.h>

#include <locale.h>

#include <sys/ioctl.h>

#include <sys/mman.h>

#include "perf_util.h"

#define SMPL_PERIOD	2400000000ULL

static volatile unsigned long notification_received;

static perf_event_desc_t *fds = NULL;

static int num_fds = 0;

static int buffer_pages = 1; /* size of buffer payload (must be power of 2)*/

static void

sigio_handler(int n, siginfo_t *info, void *uc)

{

	struct perf_event_header ehdr;

	int ret, id;

	/*

	 * positive si_code indicate kernel generated signal

	 * which is normal for SIGIO

	 */

	if (info->si_code < 0)

		errx(1, "signal not generated by kernel");

	/*

	 * SIGPOLL = SIGIO

	 * expect POLL_HUP instead of POLL_IN because we are

	 * in one-shot mode (IOC_REFRESH)

	 */

	if (info->si_code != POLL_HUP)

		errx(1, "signal not generated by SIGIO");

	id = perf_fd2event(fds, num_fds, info->si_fd);

	if (id == -1)

		errx(1, "no event associated with fd=%d", info->si_fd);

	ret = perf_read_buffer(fds+id, &ehdr, sizeof(ehdr));

	if (ret)

		errx(1, "cannot read event header");

	if (ehdr.type != PERF_RECORD_SAMPLE) {

		warnx("unexpected sample type=%d, skipping\n", ehdr.type);

		perf_skip_buffer(fds+id, ehdr.size);

		goto skip;

	}

	printf("Notification:%lu ", notification_received);

	ret = perf_display_sample(fds, num_fds, 0, &ehdr, stdout);

	/*

	 * increment our notification counter

	 */

	notification_received++;

skip:

	/*

	 * rearm the counter for one more shot

	 */

	ret = ioctl(info->si_fd, PERF_EVENT_IOC_REFRESH, 1);

	if (ret == -1)

		err(1, "cannot refresh");

}

/*

 * infinite loop waiting for notification to get out

 */

void

busyloop(void)

{

	/*

	 * busy loop to burn CPU cycles

	 */

	for(;notification_received < 20;) ;

}

int

main(int argc, char **argv)

{

	struct sigaction act;

	sigset_t new, old;

	uint64_t *val;

	size_t sz, pgsz;

	int ret, i;

	setlocale(LC_ALL, "");

	ret = pfm_initialize();

	if (ret != PFM_SUCCESS)

		errx(1, "Cannot initialize library: %s", pfm_strerror(ret));

	pgsz = sysconf(_SC_PAGESIZE);

	/*

	 * Install the signal handler (SIGIO)

	 * need SA_SIGINFO because we need the fd

	 * in the signal handler

	 */

	memset(&act, 0, sizeof(act));

	act.sa_sigaction = sigio_handler;

	act.sa_flags = SA_SIGINFO;

	sigaction (SIGIO, &act, 0);

	sigemptyset(&old;;

	sigemptyset(&new;;

	sigaddset(&new, SIGIO);

	ret = sigprocmask(SIG_SETMASK, NULL, &old;;

	if (ret)

		err(1, "sigprocmask failed");

	if (sigismember(&old, SIGIO)) {

		warnx("program started with SIGIO masked, unmasking it now\n");

		ret = sigprocmask(SIG_UNBLOCK, &new, NULL);

		if (ret)

			err(1, "sigprocmask failed");

	}

	/*

 	 * allocates fd for us

 	 */

	ret = perf_setup_list_events("cycles,"

				       "instructions",

					&fds, &num_fds);

	if (ret || (num_fds == 0))

		exit(1);

	fds[0].fd = -1;

	for(i=0; i < num_fds; i++) {

		/* want a notification for every each added to the buffer */

		fds[i].hw.disabled = !i;

		if (!i) {

			fds[i].hw.wakeup_events = 1;

			fds[i].hw.sample_type = PERF_SAMPLE_IP|PERF_SAMPLE_READ|PERF_SAMPLE_PERIOD;

			fds[i].hw.sample_period = SMPL_PERIOD;

			/* read() returns event identification for signal handler */

			fds[i].hw.read_format = PERF_FORMAT_GROUP|PERF_FORMAT_ID|PERF_FORMAT_SCALE;

		}

		fds[i].fd = perf_event_open(&fds[i].hw, 0, -1, fds[0].fd, 0);

		if (fds[i].fd == -1)

			err(1, "cannot attach event %s", fds[i].name);

	}

	sz = (3+2*num_fds)*sizeof(uint64_t);

	val = malloc(sz);

	if (!val)

		err(1, "cannot allocated memory");

	/*

	 * On overflow, the non lead events are stored in the sample.

	 * However we need some key to figure the order in which they

	 * were laid out in the buffer. The file descriptor does not

	 * work for this. Instead, we extract a unique ID for each event.

	 * That id will be part of the sample for each event value.

	 * Therefore we will be able to match value to events

	 *

	 * PERF_FORMAT_ID: returns unique 64-bit identifier in addition

	 * to event value.

	 */

	if (fds[0].fd == -1)

		errx(1, "cannot create event 0");

	ret = read(fds[0].fd, val, sz);

	if (ret == -1)

		err(1, "cannot read id %zu", sizeof(val));

	/*

	 * we are using PERF_FORMAT_GROUP, therefore the structure

	 * of val is as follows:

	 *

	 *      { u64           nr;

	 *        { u64         time_enabled; } && PERF_FORMAT_ENABLED

	 *        { u64         time_running; } && PERF_FORMAT_RUNNING

	 *        { u64         value;                  

	 *          { u64       id;           } && PERF_FORMAT_ID

	 *        }             cntr[nr];               

	 * We are skipping the first 3 values (nr, time_enabled, time_running)

	 * and then for each event we get a pair of values.

	 */ 

	for(i=0; i < num_fds; i++) {

		fds[i].id = val[2*i+1+3];

		printf("%"PRIu64"  %s\n", fds[i].id, fds[i].name);

	}

	fds[0].buf = mmap(NULL, (buffer_pages+1)*pgsz, PROT_READ|PROT_WRITE, MAP_SHARED, fds[0].fd, 0);

	if (fds[0].buf == MAP_FAILED)

		err(1, "cannot mmap buffer");

	fds[0].pgmsk = (buffer_pages * pgsz) - 1;

	/*

	 * setup asynchronous notification on the file descriptor

	 */

	ret = fcntl(fds[0].fd, F_SETFL, fcntl(fds[0].fd, F_GETFL, 0) | O_ASYNC);

	if (ret == -1)

		err(1, "cannot set ASYNC");

	/*

 	 * necessary if we want to get the file descriptor for

 	 * which the SIGIO is sent in siginfo->si_fd.

 	 * SA_SIGINFO in itself is not enough

 	 */

	ret = fcntl(fds[0].fd, F_SETSIG, SIGIO);

	if (ret == -1)

		err(1, "cannot setsig");

	/*

	 * get ownership of the descriptor

	 */

	ret = fcntl(fds[0].fd, F_SETOWN, getpid());

	if (ret == -1)

		err(1, "cannot setown");

	/*

	 * enable the group for one period

	 */

	ret = ioctl(fds[0].fd, PERF_EVENT_IOC_REFRESH , 1);

	if (ret == -1)

		err(1, "cannot refresh");

	busyloop();

	ret = ioctl(fds[0].fd, PERF_EVENT_IOC_DISABLE, 1);

	if (ret == -1)

		err(1, "cannot disable");

	/*

	 * destroy our session

	 */

	for(i=0; i < num_fds; i++)

		close(fds[i].fd);

	perf_free_fds(fds, num_fds);

	free(val);

	/* free libpfm resources cleanly */

	pfm_terminate();

	return 0;

}