gmon.c

/*-
 * SPDX-License-Identifier: BSD-3-Clause
 *
 * Copyright (c) 1983, 1992, 1993
 *	The Regents of the University of California.  All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */

#include "namespace.h"
#include <sys/param.h>
#include <sys/time.h>
#include <sys/gmon.h>
#include <sys/mman.h>
#include <sys/sysctl.h>

#include <err.h>
#include <fcntl.h>
#include <inttypes.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include "un-namespace.h"

#include "libc_private.h"

struct gmonparam _gmonparam = { GMON_PROF_OFF };

static int	s_scale;
/* See profil(2) where this is described (incorrectly). */
#define	SCALE_SHIFT	16

#define ERR(s) _write(2, s, sizeof(s))

void	moncontrol(int);
static int hertz(void);
void	_mcleanup(void);

void
monstartup(u_long lowpc, u_long highpc)
{
	int o;
	char *cp;
	struct gmonparam *p = &_gmonparam;

	/*
	 * round lowpc and highpc to multiples of the density we're using
	 * so the rest of the scaling (here and in gprof) stays in ints.
	 */
	p->lowpc = ROUNDDOWN(lowpc, HISTFRACTION * sizeof(HISTCOUNTER));
	p->highpc = ROUNDUP(highpc, HISTFRACTION * sizeof(HISTCOUNTER));
	p->textsize = p->highpc - p->lowpc;
	p->kcountsize = p->textsize / HISTFRACTION;
	p->hashfraction = HASHFRACTION;
	p->fromssize = p->textsize / HASHFRACTION;
	p->tolimit = p->textsize * ARCDENSITY / 100;
	if (p->tolimit < MINARCS)
		p->tolimit = MINARCS;
	else if (p->tolimit > MAXARCS)
		p->tolimit = MAXARCS;
	p->tossize = p->tolimit * sizeof(struct tostruct);

	cp = mmap(NULL, p->kcountsize + p->fromssize + p->tossize,
	    PROT_READ | PROT_WRITE, MAP_ANON, -1, 0);
	if (cp == MAP_FAILED) {
		ERR("monstartup: out of memory\n");
		return;
	}
#ifdef notdef
	bzero(cp, p->kcountsize + p->fromssize + p->tossize);
#endif
	p->tos = (struct tostruct *)cp;
	cp += p->tossize;
	p->kcount = (u_short *)cp;
	cp += p->kcountsize;
	p->froms = (u_short *)cp;

	p->tos[0].link = 0;

	o = p->highpc - p->lowpc;
	s_scale = (p->kcountsize < o) ?
	    ((uintmax_t)p->kcountsize << SCALE_SHIFT) / o : (1 << SCALE_SHIFT);
	moncontrol(1);
}

void
_mcleanup(void)
{
	int fd;
	int fromindex;
	int endfrom;
	u_long frompc;
	int toindex;
	struct rawarc rawarc;
	struct gmonparam *p = &_gmonparam;
	struct gmonhdr gmonhdr, *hdr;
	struct clockinfo clockinfo;
	char outname[128];
	int mib[2];
	size_t size;
#ifdef DEBUG
	int log, len;
	char buf[200];
#endif

	if (p->state == GMON_PROF_ERROR)
		ERR("_mcleanup: tos overflow\n");

	size = sizeof(clockinfo);
	mib[0] = CTL_KERN;
	mib[1] = KERN_CLOCKRATE;
	if (sysctl(mib, 2, &clockinfo, &size, NULL, 0) < 0) {
		/*
		 * Best guess
		 */
		clockinfo.profhz = hertz();
	} else if (clockinfo.profhz == 0) {
		if (clockinfo.hz != 0)
			clockinfo.profhz = clockinfo.hz;
		else
			clockinfo.profhz = hertz();
	}

	moncontrol(0);
	if (getenv("PROFIL_USE_PID"))
		snprintf(outname, sizeof(outname), "%s.%d.gmon",
		    _getprogname(), getpid());
	else
		snprintf(outname, sizeof(outname), "%s.gmon", _getprogname());

	fd = _open(outname, O_CREAT|O_TRUNC|O_WRONLY|O_CLOEXEC, 0666);
	if (fd < 0) {
		_warn("_mcleanup: %s", outname);
		return;
	}
#ifdef DEBUG
	log = _open("gmon.log", O_CREAT|O_TRUNC|O_WRONLY|O_CLOEXEC, 0664);
	if (log < 0) {
		_warn("_mcleanup: gmon.log");
		return;
	}
	len = sprintf(buf, "[mcleanup1] kcount 0x%p ssiz %lu\n",
	    p->kcount, p->kcountsize);
	_write(log, buf, len);
#endif
	hdr = (struct gmonhdr *)&gmonhdr;
	bzero(hdr, sizeof(*hdr));
	hdr->lpc = p->lowpc;
	hdr->hpc = p->highpc;
	hdr->ncnt = p->kcountsize + sizeof(gmonhdr);
	hdr->version = GMONVERSION;
	hdr->profrate = clockinfo.profhz;
	_write(fd, (char *)hdr, sizeof *hdr);
	_write(fd, p->kcount, p->kcountsize);
	endfrom = p->fromssize / sizeof(*p->froms);
	for (fromindex = 0; fromindex < endfrom; fromindex++) {
		if (p->froms[fromindex] == 0)
			continue;

		frompc = p->lowpc;
		frompc += fromindex * p->hashfraction * sizeof(*p->froms);
		for (toindex = p->froms[fromindex]; toindex != 0;
		     toindex = p->tos[toindex].link) {
#ifdef DEBUG
			len = sprintf(buf,
			"[mcleanup2] frompc 0x%lx selfpc 0x%lx count %lu\n" ,
				frompc, p->tos[toindex].selfpc,
				p->tos[toindex].count);
			_write(log, buf, len);
#endif
			rawarc.raw_frompc = frompc;
			rawarc.raw_selfpc = p->tos[toindex].selfpc;
			rawarc.raw_count = p->tos[toindex].count;
			_write(fd, &rawarc, sizeof rawarc);
		}
	}
	_close(fd);
}

/*
 * Control profiling
 *	profiling is what mcount checks to see if
 *	all the data structures are ready.
 */
void
moncontrol(int mode)
{
	struct gmonparam *p = &_gmonparam;

	if (mode) {
		/* start */
		profil((char *)p->kcount, p->kcountsize, p->lowpc, s_scale);
		p->state = GMON_PROF_ON;
	} else {
		/* stop */
		profil((char *)0, 0, 0, 0);
		p->state = GMON_PROF_OFF;
	}
}

/*
 * discover the tick frequency of the machine
 * if something goes wrong, we return 0, an impossible hertz.
 */
static int
hertz(void)
{
	struct itimerval tim;

	tim.it_interval.tv_sec = 0;
	tim.it_interval.tv_usec = 1;
	tim.it_value.tv_sec = 0;
	tim.it_value.tv_usec = 0;
	setitimer(ITIMER_REAL, &tim, 0);
	setitimer(ITIMER_REAL, 0, &tim);
	if (tim.it_interval.tv_usec < 2)
		return(0);
	return (1000000 / tim.it_interval.tv_usec);
}