/*

 * task_attach_timeout.c - attach to another task for monitoring for a short while

 *

 * Copyright (c) 2002-2006 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.

 *

 * This file is part of libpfm, a performance monitoring support library for

 * applications on Linux/ia64.

 */

#include <sys/types.h>

#include <inttypes.h>

#include <stdio.h>

#include <stdlib.h>

#include <stdarg.h>

#include <errno.h>

#include <unistd.h>

#include <string.h>

#include <stdarg.h>

#include <sys/wait.h>

#include <sys/ptrace.h>

#include <sys/poll.h>

#include <perfmon/pfmlib.h>

#include <perfmon/perfmon.h>

#define NUM_PMCS PFMLIB_MAX_PMCS

#define NUM_PMDS PFMLIB_MAX_PMDS

#define MAX_EVT_NAME_LEN	128

static void fatal_error(char *fmt,...) __attribute__((noreturn));

static void

fatal_error(char *fmt, ...)

{

	va_list ap;

	va_start(ap, fmt);

	vfprintf(stderr, fmt, ap);

	va_end(ap);

	exit(1);

}

int

parent(pid_t pid, unsigned long delay)

{

	pfmlib_input_param_t inp;

	pfmlib_output_param_t outp;

	pfarg_context_t ctx[1];

	pfarg_reg_t pc[NUM_PMCS];

	pfarg_reg_t pd[NUM_PMDS];

	pfarg_load_t load_args;

	struct pollfd pollfd;

	pfm_msg_t msg;

	unsigned int i, num_counters;

	int status, ret;

	int ctx_fd;

	char name[MAX_EVT_NAME_LEN];

	memset(pc, 0, sizeof(ctx));

	memset(pd, 0, sizeof(ctx));

	memset(ctx, 0, sizeof(ctx));

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

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

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

	pfm_get_num_counters(&num_counters);

	if (pfm_get_cycle_event(&inp.pfp_events[0]) != PFMLIB_SUCCESS)

		fatal_error("cannot find cycle event\n");

	if (pfm_get_inst_retired_event(&inp.pfp_events[1]) != PFMLIB_SUCCESS)

		fatal_error("cannot find inst retired event\n");

	i = 2;

	if (num_counters < i) {

		i = num_counters;

		printf("too many events provided (max=%d events), using first %d event(s)\n", num_counters, i);

	}

	/*

	 * set the privilege mode:

	 * 	PFM_PLM3 : user level

	 * 	PFM_PLM0 : kernel level

	 */

	inp.pfp_dfl_plm   = PFM_PLM3;

	/*

	 * how many counters we use

	 */

	inp.pfp_event_count = i;

	/*

	 * let the library figure out the values for the PMCS

	 */

	if ((ret=pfm_dispatch_events(&inp, NULL, &outp, NULL)) != PFMLIB_SUCCESS) {

		fatal_error("cannot configure events: %s\n", pfm_strerror(ret));

	}

	/*

	 * now create a context. we will later attach it to the task we are creating.

	 */

	if (perfmonctl(0, PFM_CREATE_CONTEXT, ctx, 1) == -1) {

		if (errno == ENOSYS) {

			fatal_error("Your kernel does not have performance monitoring support!\n");

		}

		fatal_error("Can't create PFM context %s\n", strerror(errno));

	}

	/*

	 * extract the identifier for our context

	 */

	ctx_fd = ctx[0].ctx_fd;

	/*

	 * use our file descriptor for the poll.

	 * we are interested in read events only.

	 */

	pollfd.fd     = ctx_fd;

	pollfd.events = POLLIN;

	/*

	 * Now prepare the argument to initialize the PMDs and PMCS.

	 * We must pfp_pmc_count to determine the number of PMC to intialize.

	 * We must use pfp_event_count to determine the number of PMD to initialize.

	 * Some events causes extra PMCs to be used, so  pfp_pmc_count may be >= pfp_event_count.

	 *

	 * This step is new compared to libpfm-2.x. It is necessary because the library no

	 * longer knows about the kernel data structures.

	 */

	for (i=0; i < outp.pfp_pmc_count; i++) {

		pc[i].reg_num   = outp.pfp_pmcs[i].reg_num;

		pc[i].reg_value = outp.pfp_pmcs[i].reg_value;

	}

	/*

	 * the PMC controlling the event ALWAYS come first, that's why this loop

	 * is safe even when extra PMC are needed to support a particular event.

	 */

	for (i=0; i < inp.pfp_event_count; i++) {

		pd[i].reg_num   = pc[i].reg_num;

	}

	/*

	 * Now program the registers

	 *

	 * We don't use the save variable to indicate the number of elements passed to

	 * the kernel because, as we said earlier, pc may contain more elements than

	 * the number of events we specified, i.e., contains more thann counting monitors.

	 */

	if (perfmonctl(ctx_fd, PFM_WRITE_PMCS, pc, outp.pfp_pmc_count) == -1) {

		fatal_error("perfmonctl error PFM_WRITE_PMCS errno %d\n",errno);

	}

	if (perfmonctl(ctx_fd, PFM_WRITE_PMDS, pd, inp.pfp_event_count) == -1) {

		fatal_error("perfmonctl error PFM_WRITE_PMDS errno %d\n",errno);

	}

	ret = ptrace(PTRACE_ATTACH, pid, NULL, 0);

	if (ret == -1) {

		fatal_error("cannot attach to %d: %s\n", pid, strerror(errno));

	}

	/*

	 * wait for the child to be actually stopped

	 */

	waitpid(pid, &status, WUNTRACED);

	/*

	 * check if process exited early

	 */

	if (WIFEXITED(status)) {

		fatal_error("command process %d exited too early with status %d\n", pid, WEXITSTATUS(status));

	}

	/*

	 * the task is stopped at this point

	 */

	/*

	 * now we load (i.e., attach) the context to ourself

	 */

	load_args.load_pid = pid;

	if (perfmonctl(ctx_fd, PFM_LOAD_CONTEXT, &load_args, 1) == -1) {

		fatal_error("perfmonctl error PFM_LOAD_CONTEXT errno %d\n",errno);

	}

	/*

	 * activate monitoring. The task is still STOPPED at this point. Monitoring

	 * will not take effect until the execution of the task is resumed.

	 */

	if (perfmonctl(ctx_fd, PFM_START, NULL, 0) == -1) {

		fatal_error("perfmonctl error PFM_START errno %d\n",errno);

	}

	/*

	 * now resume execution of the task, effectively activating

	 * monitoring.

	 */

	ptrace(PTRACE_DETACH, pid, NULL, 0);

	printf("attached to [%d], timeout set to %lu seconds\n", pid, delay);

	/*

	 * now the task is running

	 */

	/*

	 * We cannot simply do a waitpid() because we may be attaching to a process

	 * totally unrelated to our program. Instead we use a perfmon facility that

	 * notifies us when the monitoring task is exiting.

	 *

	 * When a task with a monitoring context attached to it exits, a PFM_MSG_END

	 * is generated. It can be retrieve with a simple read() on the context's descriptor.

	 *

	 * Another reason why you might return from the read is if there was a counter

	 * overflow, unlikely in this example.

	 *

	 * To measure only for short period of time, use select or poll with a timeout,

	 * see task_attach_timeout.c

	 *

	 */

	ret = poll(&pollfd, 1, delay*1000);

	switch( ret ) {

		case -1:

			fatal_error("cannot read from descriptor: %s\n", strerror(errno));

			/* no return */

		case  1:

			/*

	 		 * there is a message, i.e., the program exited before our timeout

	 		 */

			if (ret == 1) {

				/*

		 		* extract message

		 		*/

				ret = read(ctx_fd, &msg, sizeof(msg));

				if (msg.type != PFM_MSG_END) {

					fatal_error("unexpected msg type : %d\n", msg.type);

				}

			}

			break;

		case   0:

			/*

			 * we timed out, we need to stop the task to unload

			 */

			ret = ptrace(PTRACE_ATTACH, pid, NULL, 0);

			if (ret == -1) {

				fatal_error("cannot attach to %d: %s\n", pid, strerror(errno));

			}

			/*

			 * wait for task to be actually stopped

			 */

			waitpid(pid, &status, WUNTRACED);

			/*

	 		 * check if process exited, then no need to unload

	 		 */

			if (WIFEXITED(status)) goto read_results;

			if (perfmonctl(ctx_fd, PFM_UNLOAD_CONTEXT, NULL, 0) == -1) {

				fatal_error("perfmonctl error PFM_UNLOAD_CONTEXT errno %d\n",errno);

			}

			/*

			 * let it run free again

			 */

			ptrace(PTRACE_DETACH, pid, NULL, 0);

			break;

		default:

			fatal_error("unexpected return from poll: %d\n", ret);

	}

read_results:

	/*

	 * now simply read the results.

	 */

	if (perfmonctl(ctx_fd, PFM_READ_PMDS, pd, inp.pfp_event_count) == -1) {

		fatal_error("perfmonctl error READ_PMDS errno %d\n",errno);

		return -1;

	}

	/*

	 * print the results

	 *

	 * It is important to realize, that the first event we specified may not

	 * be in PMD4. Not all events can be measured by any monitor. That's why

	 * we need to use the pc[] array to figure out where event i was allocated.

	 *

	 */

	for (i=0; i < inp.pfp_event_count; i++) {

		pfm_get_full_event_name(&inp.pfp_events[i], name, MAX_EVT_NAME_LEN);

		printf("PMD%u %20"PRIu64" %s\n",

			pd[i].reg_num,

			pd[i].reg_value,

			name);

	}

	/*

	 * free the context

	 */

	close(ctx_fd);

	return 0;

}

int

main(int argc, char **argv)

{

	pfmlib_options_t pfmlib_options;

	unsigned long delay;

	pid_t pid;

	if (argc < 2) {

		fatal_error("usage: %s pid [timeout]\n", argv[0]);

	}

	pid   = atoi(argv[1]);

	delay = argc > 2 ? strtoul(argv[2], NULL, 10) : 10;

	/*

	 * Initialize pfm library (required before we can use it)

	 */

	if (pfm_initialize() != PFMLIB_SUCCESS) {

		printf("Can't initialize library\n");

		exit(1);

	}

	/*

	 * pass options to library (optional)

	 */

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

	pfmlib_options.pfm_debug = 0; /* set to 1 for debug */

	pfm_set_options(&pfmlib_options);

	return parent(pid, delay);

}