/*

 * bts_smpl.c - example of Intel Branch Trace Stack sampling

 *

 * Copyright (c) 2009 Google, Inc

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

 *

 * Based on:

 * Copyright (c) 2003-2006 Hewlett-Packard Development Company, L.P.

 * Contributed by Stephane Eranian <eranian@hpl.hp.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 <stdio.h>

#include <stdlib.h>

#include <stdarg.h>

#include <errno.h>

#include <unistd.h>

#include <string.h>

#include <signal.h>

#include <stdarg.h>

#include <getopt.h>

#include <setjmp.h>

#include <limits.h>

#include <time.h>

#include <sys/time.h>

#include <sys/ptrace.h>

#include <sys/wait.h>

#include <sys/poll.h>

#include <sys/mman.h>

#include <sys/resource.h>

#include <err.h>

#include "perf_util.h"

#define SMPL_PERIOD	24000000ULL

typedef struct {

	int opt_no_show;

	int opt_inherit;

	int mmap_pages;

} options_t;

static jmp_buf jbuf;

static uint64_t collected_samples, lost_samples;

static perf_event_desc_t *fds;

static int num_fds;

static options_t options;

static struct option the_options[]={

	{ "help", 0, 0,  1},

	{ "no-show", 0, &options.opt_no_show, 1},

	{ 0, 0, 0, 0}

};

static void

cld_handler(int n)

{

	longjmp(jbuf, 1);

}

int

child(char **arg)

{

	/*

	 * force the task to stop before executing the first

	 * user level instruction

	 */

	ptrace(PTRACE_TRACEME, 0, NULL, NULL);

	execvp(arg[0], arg);

	/* not reached */

	return -1;

}

struct timeval last_read, this_read;

static void

process_smpl_buf(perf_event_desc_t *hw)

{

	struct perf_event_header ehdr;

	int ret;

	for(;;) {

		ret = perf_read_buffer(hw, &ehdr, sizeof(ehdr));

		if (ret)

			return; /* nothing to read */

		switch(ehdr.type) {

			case PERF_RECORD_SAMPLE:

				perf_display_sample(fds, num_fds, hw - fds, &ehdr, stdout);

				collected_samples++;

				break;

			case PERF_RECORD_EXIT:

				display_exit(hw, stdout);

				break;

			case PERF_RECORD_LOST:

				display_lost(hw, fds, num_fds, stdout);

				break;

			case PERF_RECORD_THROTTLE:

				display_freq(1, hw, stdout);

				break;

			case PERF_RECORD_UNTHROTTLE:

				display_freq(0, hw, stdout);

				break;

			default:

				printf("unknown sample type %d sz=%d\n", ehdr.type, ehdr.size);

				perf_skip_buffer(hw, ehdr.size - sizeof(ehdr));

		}

	}

}

int

mainloop(char **arg)

{

	static uint64_t ovfl_count; /* static to avoid setjmp issue */

	struct pollfd pollfds[1];

	size_t map_size = 0;

	sigset_t bmask;

	pid_t pid;

	uint64_t val[2];

	int status, ret;

	if (pfm_initialize() != PFM_SUCCESS)

		errx(1, "libpfm initialization failed\n");

	map_size = (options.mmap_pages+1)*getpagesize();

	/*

	 * does allocate fds

	 */

	ret = perf_setup_list_events("branches:u", &fds, &num_fds);

	if (ret || !num_fds)

		errx(1, "cannot setup event");

	memset(pollfds, 0, sizeof(pollfds));

	/*

	 * Create the child task

	 */

	if ((pid=fork()) == -1)

		err(1, "cannot fork process\n");

	if (pid == 0)

		exit(child(arg));

	/*

	 * wait for the child to exec

	 */

	ret = waitpid(pid, &status, WUNTRACED);

	if (ret == -1)

		err(1, "waitpid failed");

	if (WIFEXITED(status))

		errx(1, "task %s [%d] exited already status %d\n", arg[0], pid, WEXITSTATUS(status));

	fds[0].fd = -1;

	fds[0].hw.disabled = 0; /* start immediately */

	if (options.opt_inherit)

		fds[0].hw.inherit = 1;

	fds[0].hw.sample_type = PERF_SAMPLE_IP|PERF_SAMPLE_ADDR;

	/*

	 * BTS only supported at user level

	 */

	if (fds[0].hw.exclude_user ||fds[0].hw.exclude_kernel == 0)

		errx(1, "BTS currently supported only at the user level\n");

	/*

	 * period MUST be one to trigger BTS: tracing not sampling anymore

	 */

	fds[0].hw.sample_period = 1;

	fds[0].hw.exclude_kernel = 1;

	fds[0].hw.exclude_hv = 1;

	fds[0].hw.read_format |= PERF_FORMAT_ID;

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

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

		err(1, "cannot attach event %s", fds[0].name);

	fds[0].buf = mmap(NULL, map_size, PROT_READ|PROT_WRITE, MAP_SHARED, fds[0].fd, 0);

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

		err(1, "cannot mmap buffer");

	/* does not include header page */

	fds[0].pgmsk = (options.mmap_pages*getpagesize())-1;

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

	if (ret == -1)

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

	fds[0].id = val[1];

	printf("%"PRIu64"  %s\n", fds[0].id, fds[0].name);

	/*

	 * effectively activate monitoring

	 */

	ptrace(PTRACE_DETACH, pid, NULL, 0);

	signal(SIGCHLD, cld_handler);

	pollfds[0].fd = fds[0].fd;

	pollfds[0].events = POLLIN;

	if (setjmp(jbuf) == 1)

		goto terminate_session;

	sigemptyset(&bmask);

	sigaddset(&bmask, SIGCHLD);

	/*

	 * core loop

	 */

	for(;;) {

		ret = poll(pollfds, 1, -1);

		if (ret < 0 && errno == EINTR)

			break;

		ovfl_count++;

		ret = sigprocmask(SIG_SETMASK, &bmask, NULL);

		if (ret)

			err(1, "setmask");

		process_smpl_buf(&fds[0]);

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

		if (ret)

			err(1, "unblock");

	}

terminate_session:

	/*

	 * cleanup child

	 */

	wait4(pid, &status, 0, NULL);

	close(fds[0].fd);

	/* check for partial event buffer */

	process_smpl_buf(&fds[0]);

	munmap(fds[0].buf, map_size);

	free(fds);

	printf("%"PRIu64" samples collected in %"PRIu64" poll events, %"PRIu64" lost samples\n",

		collected_samples,

		ovfl_count, lost_samples);

	return 0;

}

static void

usage(void)

{

	printf("usage: bts_smpl [-h] [--help] [-i] [-m mmap_pages] cmd\n");

}

int

main(int argc, char **argv)

{

	int c;

	while ((c=getopt_long(argc, argv,"+hm:p:if", the_options, 0)) != -1) {

		switch(c) {

			case 0: continue;

			case 'i':

				options.opt_inherit = 1;

				break;

			case 'm':

				if (options.mmap_pages)

					errx(1, "mmap pages already set\n");

				options.mmap_pages = atoi(optarg);

				break;

			case 'h':

				usage();

				exit(0);

			default:

				errx(1, "unknown option");

		}

	}

	if (argv[optind] == NULL)

		errx(1, "you must specify a command to execute\n");

	if (!options.mmap_pages)

		options.mmap_pages = 4;

	return mainloop(argv+optind);

}