glibc/gmon/gmon.c

/*-
 * Copyright (c) 1983, 1992, 1993, 2011
 *	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.
 * 4. 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 <sys/param.h>
#include <sys/time.h>
#include <sys/gmon.h>
#include <sys/gmon_out.h>
#include <sys/uio.h>

#include <errno.h>
#include <stdio.h>
#include <fcntl.h>
#include <unistd.h>
#include <wchar.h>

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <stddef.h>
#include <unistd.h>
#include <libc-internal.h>
#include <not-cancel.h>

#define TUNABLE_NAMESPACE gmon
#include <elf/dl-tunables.h>

#ifdef PIC
# include <link.h>

static int
callback (struct dl_phdr_info *info, size_t size, void *data)
{
  if (info->dlpi_name[0] == '\0')
    {
      /* The link map for the executable is created by calling
	 _dl_new_object with "" as filename.  dl_iterate_phdr
	 calls the callback function with filename from the
	 link map as dlpi_name.  */
      u_long *load_address = data;
      *load_address = (u_long) info->dlpi_addr;
      return 1;
    }

  return 0;
}
#endif

/*  Head of basic-block list or NULL. */
struct __bb *__bb_head attribute_hidden;

struct gmonparam _gmonparam attribute_hidden = { GMON_PROF_OFF };

/*
 * See profil(2) where this is described:
 */
static int	s_scale;
#define		SCALE_1_TO_1	0x10000L

#define ERR(s) __write_nocancel (STDERR_FILENO, s, sizeof (s) - 1)

void moncontrol (int mode);
void __moncontrol (int mode);
libc_hidden_proto (__moncontrol)
static void write_hist (int fd, u_long load_address);
static void write_call_graph (int fd, u_long load_address);
static void write_bb_counts (int 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;

  /* Treat start request as stop if error or gmon not initialized. */
  if (mode && p->state != GMON_PROF_ERROR && p->tos != NULL)
    {
      /* start */
      __profil((void *) p->kcount, p->kcountsize, p->lowpc, s_scale);
      p->state = GMON_PROF_ON;
    }
  else
    {
      /* stop */
      __profil(NULL, 0, 0, 0);
      /* Don't change the state if we ran into an error. */
      if (p->state != GMON_PROF_ERROR)
        p->state = GMON_PROF_OFF;
    }
}
libc_hidden_def (__moncontrol)
weak_alias (__moncontrol, moncontrol)


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

  /* Read minarcs/maxarcs tunables. */
  minarcs = TUNABLE_GET (minarcs, int32_t, NULL);
  maxarcs = TUNABLE_GET (maxarcs, int32_t, NULL);
  if (maxarcs < minarcs)
    {
      ERR("monstartup: maxarcs < minarcs, setting maxarcs = minarcs\n");
      maxarcs = minarcs;
    }

  /*
   * If we are incorrectly called twice in a row (without an
   * intervening call to _mcleanup), ignore the second call to
   * prevent leaking memory.
   */
  if (p->tos != NULL)
      return;

  /*
   * 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;
  /* This looks like a typo, but it's here to align the p->froms
     section.  */
  p->kcountsize = ROUNDUP(p->textsize / HISTFRACTION, sizeof(*p->froms));
  p->hashfraction = HASHFRACTION;
  p->log_hashfraction = -1;
  /* The following test must be kept in sync with the corresponding
     test in mcount.c.  */
  if ((HASHFRACTION & (HASHFRACTION - 1)) == 0) {
      /* if HASHFRACTION is a power of two, mcount can use shifting
	 instead of integer division.  Precompute shift amount. */
      p->log_hashfraction = ffs(p->hashfraction * sizeof(*p->froms)) - 1;
  }
  p->fromssize = ROUNDUP(p->textsize / HASHFRACTION, sizeof(*p->froms));
  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 = calloc (p->kcountsize + p->fromssize + p->tossize, 1);
  if (! cp)
    {
      ERR("monstartup: out of memory\n");
      p->tos = NULL;
      p->state = GMON_PROF_ERROR;
      return;
    }
  p->tos = (struct tostruct *)cp;
  cp += p->tossize;
  p->kcount = (HISTCOUNTER *)cp;
  cp += p->kcountsize;
  p->froms = (ARCINDEX *)cp;

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

  o = p->highpc - p->lowpc;
  if (p->kcountsize < (u_long) o)
    {
#ifndef hp300
      s_scale = ((float)p->kcountsize / o ) * SCALE_1_TO_1;
#else
      /* avoid floating point operations */
      int quot = o / p->kcountsize;

      if (quot >= 0x10000)
	s_scale = 1;
      else if (quot >= 0x100)
	s_scale = 0x10000 / quot;
      else if (o >= 0x800000)
	s_scale = 0x1000000 / (o / (p->kcountsize >> 8));
      else
	s_scale = 0x1000000 / ((o << 8) / p->kcountsize);
#endif
    } else
      s_scale = SCALE_1_TO_1;

  __moncontrol(1);
}
weak_alias (__monstartup, monstartup)


static void
write_hist (int fd, u_long load_address)
{
  u_char tag = GMON_TAG_TIME_HIST;

  if (_gmonparam.kcountsize > 0)
    {
      struct real_gmon_hist_hdr
      {
	char *low_pc;
	char *high_pc;
	int32_t hist_size;
	int32_t prof_rate;
	char dimen[15];
	char dimen_abbrev;
      } thdr;
      struct iovec iov[3] =
	{
	  { &tag, sizeof (tag) },
	  { &thdr, sizeof (struct gmon_hist_hdr) },
	  { _gmonparam.kcount, _gmonparam.kcountsize }
	};

      if (sizeof (thdr) != sizeof (struct gmon_hist_hdr)
	  || (offsetof (struct real_gmon_hist_hdr, low_pc)
	      != offsetof (struct gmon_hist_hdr, low_pc))
	  || (offsetof (struct real_gmon_hist_hdr, high_pc)
	      != offsetof (struct gmon_hist_hdr, high_pc))
	  || (offsetof (struct real_gmon_hist_hdr, hist_size)
	      != offsetof (struct gmon_hist_hdr, hist_size))
	  || (offsetof (struct real_gmon_hist_hdr, prof_rate)
	      != offsetof (struct gmon_hist_hdr, prof_rate))
	  || (offsetof (struct real_gmon_hist_hdr, dimen)
	      != offsetof (struct gmon_hist_hdr, dimen))
	  || (offsetof (struct real_gmon_hist_hdr, dimen_abbrev)
	      != offsetof (struct gmon_hist_hdr, dimen_abbrev)))
	abort ();

      thdr.low_pc = (char *) _gmonparam.lowpc - load_address;
      thdr.high_pc = (char *) _gmonparam.highpc - load_address;
      thdr.hist_size = _gmonparam.kcountsize / sizeof (HISTCOUNTER);
      thdr.prof_rate = __profile_frequency ();
      strncpy (thdr.dimen, "seconds", sizeof (thdr.dimen));
      thdr.dimen_abbrev = 's';

      __writev_nocancel_nostatus (fd, iov, 3);
    }
}


static void
write_call_graph (int fd, u_long load_address)
{
#define NARCS_PER_WRITEV	32
  u_char tag = GMON_TAG_CG_ARC;
  struct gmon_cg_arc_record raw_arc[NARCS_PER_WRITEV]
    __attribute__ ((aligned (__alignof__ (char*))));
  ARCINDEX from_index, to_index;
  u_long from_len;
  u_long frompc;
  struct iovec iov[2 * NARCS_PER_WRITEV];
  int nfilled;

  for (nfilled = 0; nfilled < NARCS_PER_WRITEV; ++nfilled)
    {
      iov[2 * nfilled].iov_base = &tag;
      iov[2 * nfilled].iov_len = sizeof (tag);

      iov[2 * nfilled + 1].iov_base = &raw_arc[nfilled];
      iov[2 * nfilled + 1].iov_len = sizeof (struct gmon_cg_arc_record);
    }

  nfilled = 0;
  from_len = _gmonparam.fromssize / sizeof (*_gmonparam.froms);
  for (from_index = 0; from_index < from_len; ++from_index)
    {
      if (_gmonparam.froms[from_index] == 0)
	continue;

      frompc = _gmonparam.lowpc;
      frompc += (from_index * _gmonparam.hashfraction
		 * sizeof (*_gmonparam.froms));
      for (to_index = _gmonparam.froms[from_index];
	   to_index != 0;
	   to_index = _gmonparam.tos[to_index].link)
	{
	  struct arc
	    {
	      char *frompc;
	      char *selfpc;
	      int32_t count;
	    }
	  arc;

	  arc.frompc = (char *) frompc - load_address;
	  arc.selfpc = ((char *) _gmonparam.tos[to_index].selfpc
			- load_address);
	  arc.count  = _gmonparam.tos[to_index].count;
	  memcpy (raw_arc + nfilled, &arc, sizeof (raw_arc [0]));

	  if (++nfilled == NARCS_PER_WRITEV)
	    {
	      __writev_nocancel_nostatus (fd, iov, 2 * nfilled);
	      nfilled = 0;
	    }
	}
    }
  if (nfilled > 0)
    __writev_nocancel_nostatus (fd, iov, 2 * nfilled);
}


static void
write_bb_counts (int fd)
{
  struct __bb *grp;
  u_char tag = GMON_TAG_BB_COUNT;
  size_t ncounts;
  size_t i;

  struct iovec bbhead[2] =
    {
      { &tag, sizeof (tag) },
      { &ncounts, sizeof (ncounts) }
    };
  struct iovec bbbody[8];
  size_t nfilled;

  for (i = 0; i < (sizeof (bbbody) / sizeof (bbbody[0])); i += 2)
    {
      bbbody[i].iov_len = sizeof (grp->addresses[0]);
      bbbody[i + 1].iov_len = sizeof (grp->counts[0]);
    }

  /* Write each group of basic-block info (all basic-blocks in a
     compilation unit form a single group). */

  for (grp = __bb_head; grp; grp = grp->next)
    {
      ncounts = grp->ncounts;
      __writev_nocancel_nostatus (fd, bbhead, 2);
      for (nfilled = i = 0; i < ncounts; ++i)
	{
	  if (nfilled > (sizeof (bbbody) / sizeof (bbbody[0])) - 2)
	    {
	      __writev_nocancel_nostatus (fd, bbbody, nfilled);
	      nfilled = 0;
	    }

	  bbbody[nfilled++].iov_base = (char *) &grp->addresses[i];
	  bbbody[nfilled++].iov_base = &grp->counts[i];
	}
      if (nfilled > 0)
	__writev_nocancel_nostatus (fd, bbbody, nfilled);
    }
}


static void
write_gmon (void)
{
    int fd = -1;
    char *env;

    env = getenv ("GMON_OUT_PREFIX");
    if (env != NULL && !__libc_enable_secure)
      {
	size_t len = strlen (env);
	char buf[len + 20];
	__snprintf (buf, sizeof (buf), "%s.%u", env, __getpid ());
	fd = __open_nocancel (buf, O_CREAT | O_TRUNC | O_WRONLY | O_NOFOLLOW
			      | O_CLOEXEC, 0666);
      }

    if (fd == -1)
      {
	fd = __open_nocancel ("gmon.out", O_CREAT | O_TRUNC | O_WRONLY
			      | O_NOFOLLOW | O_CLOEXEC, 0666);
	if (fd < 0)
	  {
	    char buf[300];
	    int errnum = errno;
	    __fxprintf (NULL, "_mcleanup: gmon.out: %s\n",
			__strerror_r (errnum, buf, sizeof buf));
	    return;
	  }
      }

    /* write gmon.out header: */
    struct real_gmon_hdr
    {
      char cookie[4];
      int32_t version;
      char spare[3 * 4];
    } ghdr;
    if (sizeof (ghdr) != sizeof (struct gmon_hdr)
	|| (offsetof (struct real_gmon_hdr, cookie)
	    != offsetof (struct gmon_hdr, cookie))
	|| (offsetof (struct real_gmon_hdr, version)
	    != offsetof (struct gmon_hdr, version)))
      abort ();
    memcpy (&ghdr.cookie[0], GMON_MAGIC, sizeof (ghdr.cookie));
    ghdr.version = GMON_VERSION;
    memset (ghdr.spare, '\0', sizeof (ghdr.spare));
    __write_nocancel (fd, &ghdr, sizeof (struct gmon_hdr));

    /* Get load_address to profile PIE.  */
    u_long load_address = 0;
#ifdef PIC
    __dl_iterate_phdr (callback, &load_address);
#endif

    /* write PC histogram: */
    write_hist (fd, load_address);

    /* write call-graph: */
    write_call_graph (fd, load_address);

    /* write basic-block execution counts: */
    write_bb_counts (fd);

    __close_nocancel_nostatus (fd);
}


#ifdef PROF
void
__write_profiling (void)
{
  int save = _gmonparam.state;
  _gmonparam.state = GMON_PROF_OFF;
  if (save == GMON_PROF_ON)
    write_gmon ();
  _gmonparam.state = save;
}

/* This symbol isn't used anywhere in the DSO and it is not exported.
   This would normally mean it should be removed to get the same API
   in static libraries.  But since profiling is special in static libs
   anyway we keep it.  But not when building the DSO since some
   quality assurance tests will otherwise trigger.  */
weak_alias (__write_profiling, write_profiling)
#endif


void
_mcleanup (void)
{
  __moncontrol (0);

  if (_gmonparam.state != GMON_PROF_ERROR && _gmonparam.tos != NULL)
    write_gmon ();

  /* free the memory. */
  free (_gmonparam.tos);

  /* reset buffer to initial state for safety */
  memset(&_gmonparam, 0, sizeof _gmonparam);
  /* somewhat confusingly, ON=0, OFF=3 */
  _gmonparam.state = GMON_PROF_OFF;
}