/*

 * smpl_core_pebs_sys.c - Intel Core processor PEBS system-wide example 

 *

 * Copyright (c) 2008 Google, Inc

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

 *

 * Based on code:

 * Copyright (c) 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.

 */

#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 <signal.h>

#include <syscall.h>

#include <unistd.h>

#include <poll.h>

#include <sys/wait.h>

#include <sys/mman.h>

#include <perfmon/perfmon.h>

#include <perfmon/perfmon_pebs_core_smpl.h>

#include <perfmon/pfmlib.h>

#include <perfmon/pfmlib_core.h>

#include <perfmon/pfmlib_intel_atom.h>

#include "../detect_pmcs.h"

#define SMPL_EVENT	"INSTRUCTIONS_RETIRED" /* not all event support PEBS */

#define NUM_PMCS	16

#define NUM_PMDS	16

#define SMPL_PERIOD	100000ULL	 /* must not use more bits than actual HW counter width */

typedef pfm_pebs_core_smpl_hdr_t	smpl_hdr_t;

typedef pfm_pebs_core_smpl_entry_t	smpl_entry_t;

typedef pfm_pebs_core_smpl_arg_t	smpl_arg_t;

#define FMT_NAME			PFM_PEBS_CORE_SMPL_NAME

static uint64_t collected_samples;

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);

}

static void

warning(char *fmt, ...)

{

	va_list ap;

	va_start(ap, fmt);

	vfprintf(stderr, fmt, ap);

	va_end(ap);

}

int

child(char **arg)

{

	/*

	 * force the task to stop before executing the first

	 * user level instruction

	 */

	execvp(arg[0], arg);

	/* not reached */

	exit(1);

}

static void

process_smpl_buf(smpl_hdr_t *hdr)

{

	static uint64_t last_overflow = ~0; /* initialize to biggest value possible */

	static uint64_t last_count;

	smpl_entry_t *ent;

	uint64_t entry;

	unsigned long count;

	count = (hdr->ds.pebs_index - hdr->ds.pebs_buf_base)/sizeof(*ent);

	if (hdr->overflows == last_overflow && last_count == count) {

		warning("skipping identical set of samples %"PRIu64" = %"PRIu64"\n",

			hdr->overflows, last_overflow);

		return;	

	}

	last_count = count;

	last_overflow = hdr->overflows;

	/*

	 * the beginning of the buffer does not necessarily follow the header

	 * due to alignement.

	 */

	ent   = (smpl_entry_t *)((unsigned long)(hdr+1)+ hdr->start_offs);

	entry = collected_samples;

	while(count--) {

		/*

		 * print some of the machine registers of each sample

		 */

		printf("entry %06"PRIu64" eflags:0x%08llx EAX:0x%08llx ESP:0x%08llx IP:0x%08llx\n",

			entry,

			(unsigned long long)ent->eflags,

			(unsigned long long)ent->eax,

			(unsigned long long)ent->esp,

			(unsigned long long)ent->ip);

		ent++;

		entry++;

	}

	collected_samples = entry;

}

/*

 * pin task to CPU

 */

#ifndef __NR_sched_setaffinity

#error "you need to define __NR_sched_setaffinity"

#endif

#define MAX_CPUS	2048

#define NR_CPU_BITS	(MAX_CPUS>>3)

int

pin_cpu(pid_t pid, unsigned int cpu)

{

	uint64_t my_mask[NR_CPU_BITS];

	if (cpu >= MAX_CPUS)

		fatal_error("this program supports only up to %d CPUs\n", MAX_CPUS);

	my_mask[cpu>>6] = 1ULL << (cpu&63);

	return syscall(__NR_sched_setaffinity, pid, sizeof(my_mask), &my_mask);

}

static volatile int done;

static void handler(int n)

{

	done = 1;

}

int

main(int argc, char **argv)

{

	pfmlib_input_param_t inp;

	pfmlib_output_param_t outp;

	pfmlib_core_input_param_t mod_inp;

	pfmlib_options_t pfmlib_options;

	pfarg_pmr_t pc[NUM_PMCS];

	pfarg_pmd_attr_t pd[NUM_PMDS];

	pfarg_sinfo_t sif;

	struct pollfd fds;

	smpl_arg_t buf_arg;

	pfarg_msg_t msg;

	smpl_hdr_t *hdr;

	void *buf_addr;

	uint64_t pebs_size;

	pid_t pid;

	int ret, fd, type;

	unsigned int i;

	uint32_t ctx_flags;

	if (argc < 2)

		fatal_error("you need to pass a program to sample\n");

	if (pfm_initialize() != PFMLIB_SUCCESS)

		fatal_error("libpfm intialization failed\n");

	/*

	 * check we are on an Intel Core PMU

	 */

	pfm_get_pmu_type(&type);

	if (type != PFMLIB_INTEL_CORE_PMU && type != PFMLIB_INTEL_ATOM_PMU)

		fatal_error("This program only works with an Intel Core processor\n");

	/*

	 * pass options to library (optional)

	 */

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

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

	pfmlib_options.pfm_verbose = 1; /* set to 1 for verbose */

	pfm_set_options(&pfmlib_options);

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

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

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

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

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

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

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

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

	/*

	 * search for our sampling event

	 */

	if (pfm_find_full_event(SMPL_EVENT, &inp.pfp_events[0]) != PFMLIB_SUCCESS)

		fatal_error("cannot find sampling event %s\n", SMPL_EVENT);

	inp.pfp_event_count = 1;

	inp.pfp_dfl_plm = PFM_PLM3;

	/*

	 * important: inform libpfm we do use PEBS

	 */

	mod_inp.pfp_core_pebs.pebs_used = 1;

	/*

	 * sampling buffer parameters

	 */

	pebs_size = 3 * getpagesize();

	buf_arg.buf_size = pebs_size;

	/*

	 * sampling period cannot use more bits than HW counter can supoprt

	 */

	buf_arg.cnt_reset = -SMPL_PERIOD;

	/*

	 * We want a system-wide context for sampling

	 */

	ctx_flags = PFM_FL_SYSTEM_WIDE | PFM_FL_SMPL_FMT;

	/*

	 * trigger notification (interrupt) when reaching the very end of

	 * the buffer

	 */

	buf_arg.intr_thres = (pebs_size/sizeof(smpl_entry_t))*90/100;

	/*

 	 * we want to measure CPU0, thus we pin ourself to the CPU before invoking

 	 * perfmon. This ensures that the sampling buffer will be allocated on the

 	 * same NUMA node.

 	 */

	ret = pin_cpu(getpid(), 0);

	if (ret)

		fatal_error("cannot pin on CPU0");

	/*

	 * create session and sampling buffer

	 */

	fd = pfm_create(ctx_flags, &sif, FMT_NAME, &buf_arg, sizeof(buf_arg));

	if (fd == -1) {

		if (errno == ENOSYS) {

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

		}

		fatal_error("cannot create session %s, maybe you do not have the PEBS sampling format in the kernel.\nCheck /sys/kernel/perfmon/formats\n", strerror(errno));

	}

	/*

	 * map buffer into our address space

	 */

	buf_addr = mmap(NULL, (size_t)buf_arg.buf_size, PROT_READ, MAP_PRIVATE, fd, 0);

	printf("session [%d] buffer mapped @%p\n", fd, buf_addr);

	if (buf_addr == MAP_FAILED)

		fatal_error("cannot mmap sampling buffer errno %d\n", errno);

	hdr = (smpl_hdr_t *)buf_addr;

	printf("pebs_base=0x%llx pebs_end=0x%llx index=0x%llx\n"

	       "intr=0x%llx version=%u.%u\n"

	       "entry_size=%zu ds_size=%zu\n",

			(unsigned long long)hdr->ds.pebs_buf_base,

			(unsigned long long)hdr->ds.pebs_abs_max,

			(unsigned long long)hdr->ds.pebs_index,

			(unsigned long long)hdr->ds.pebs_intr_thres,

			PFM_VERSION_MAJOR(hdr->version),

			PFM_VERSION_MINOR(hdr->version),

			sizeof(smpl_entry_t),

			sizeof(hdr->ds));

	if (PFM_VERSION_MAJOR(hdr->version) < 1)

		fatal_error("invalid buffer format version\n");

	/*

	 * get which PMC registers are available

	 */

	detect_unavail_pmu_regs(&sif, &inp.pfp_unavail_pmcs, NULL);

	/*

	 * let libpfm figure out how to assign event onto PMU registers

	 */

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

		fatal_error("cannot assign event %s\n", SMPL_EVENT);

	/*

	 * propagate PMC setup from libpfm to perfmon

	 */

	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;

		/*

		 * must disable 64-bit emulation on the PMC0 counter.

		 * PMC0 is the only counter useable with PEBS. We must disable

		 * 64-bit emulation to avoid getting interrupts for each

		 * sampling period, PEBS takes care of this part.

		 */

		if (pc[i].reg_num == 0)

			pc[i].reg_flags = PFM_REGFL_NO_EMUL64;

	}

	/*

	 * propagate PMD set from libpfm to perfmon

	 */

	for (i=0; i < outp.pfp_pmd_count; i++)

		pd[i].reg_num = outp.pfp_pmds[i].reg_num;

	/*

	 * setup sampling period for first counter

	 * we want notification on overflow, i.e., when buffer is full

	 */

	pd[0].reg_flags = PFM_REGFL_OVFL_NOTIFY;

	pd[0].reg_value = -SMPL_PERIOD;

	pd[0].reg_long_reset = -SMPL_PERIOD;

	pd[0].reg_short_reset = -SMPL_PERIOD;

	/*

	 * Now program the registers

	 */

	if (pfm_write(fd, 0, PFM_RW_PMC, pc, outp.pfp_pmc_count * sizeof(*pc)) == -1)

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

	if (pfm_write(fd, 0, PFM_RW_PMD_ATTR, pd, outp.pfp_pmd_count * sizeof(*pd)) == -1)

		fatal_error("pfm_write(PMD) error errno %d\n",errno);

	/*

	 *  attach the session to CPU0

	 */

	if (pfm_attach(fd, 0, 0) == -1)

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

	/*

	 * Create the child task

	 */

	signal(SIGCHLD, handler);

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

		fatal_error("Cannot fork process\n");

	if (pid == 0) {

		/* child does not inherit context file descriptor */

		close(fd);

		/* if child is too short-lived we may not measure it */

		child(argv+1);

	}

	/*

	 * start monitoring

	 */

	if (pfm_set_state(fd, 0, PFM_ST_START) == -1)

		fatal_error("pfm_set_state(start) error errno %d\n",errno);

	fds.fd = fd;

	fds.events = POLLIN;

	/*

	 * core loop

	 */

	for(;done == 0;) {

		/*

		 * Must use a timeout to avoid a race condition

		 * with the SIGCHLD signal

		 */

		ret = poll(&fds, 1, 500);

		/*

		 * if timeout expired, then check done

		 */

		if (ret == 0)

			continue;

		if (ret == -1) {

			if(ret == -1 && errno == EINTR) {

				warning("read interrupted, retrying\n");

				continue;

			}

			fatal_error("poll failed: %s\n", strerror(errno));

		}

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

		if (ret == -1)

			fatal_error("cannot read perfmon msg: %s\n", strerror(errno));

		switch(msg.type) {

			case PFM_MSG_OVFL: /* the sampling buffer is full */

				process_smpl_buf(hdr);

				/*

				 * reactivate monitoring once we are done with the samples

				 * in syste-wide, interface guarantees monitoring is active

				 * upon return from the pfm_restart() syscall

				 */

				if (pfm_set_state(fd, 0, PFM_ST_RESTART) == -1)

					fatal_error("pfm_set_state(restart) error errno %d\n",errno);

				break;

			default: fatal_error("unknown message type %d\n", msg.type);

		}

	}

	/*

	 * cleanup child

	 */

	waitpid(pid, NULL, 0);

	/*

	 * stop monitoring, this is required in order to guarantee that the PEBS buffer

	 * header is updated with the latest position, such that we see see the final

	 * samples

	 */

	if (pfm_set_state(fd, 0, PFM_ST_STOP) == -1)

		fatal_error("pfm_set_state(stop) error errno %d\n",errno);

	/*

	 * check for any leftover samples. Must have monitoring stopped

	 * for this operation to have guarantee it is up to date

	 */

	process_smpl_buf(hdr);

	/*

	 * close session

	 */

	close(fd);

	/*

	 * unmap sampling buffer and actually free the perfmon session

	 */

	munmap(buf_addr, (size_t)buf_arg.buf_size);

	return 0;

}