Initial effort at adding profiling support.

10 files changed, 906 insertions, 1 deletions

diff --git a/libc/sysdeps/linux/common/.cvsignore b/libc/sysdeps/linux/common/.cvsignore
index f8fa8225d..0232d6900 100644
--- a/libc/sysdeps/linux/common/.cvsignore
+++ b/libc/sysdeps/linux/common/.cvsignore
@@ -1,3 +1,4 @@
 crti.S
 crtn.S
 initfini.S
+gmon-start.S
diff --git a/libc/sysdeps/linux/common/Makefile b/libc/sysdeps/linux/common/Makefile
index 5b9717f2b..d51fc4281 100644
--- a/libc/sysdeps/linux/common/Makefile
+++ b/libc/sysdeps/linux/common/Makefile
@@ -29,6 +29,9 @@ CSRC=	waitpid.c getdnnm.c gethstnm.c getcwd.c ptrace.c \
 ifneq ($(strip $(EXCLUDE_BRK)),y)
 CSRC+=sbrk.c
 endif
+ifeq ($(strip $(UCLIBC_PROFILING)),y)
+CSRC+=gmon.c
+endif
 COBJS=$(patsubst %.c,%.o, $(CSRC))
 
 MSRC=syscalls.c
@@ -44,6 +47,9 @@ SAFECFLAGS := $(subst -g,,$(SAFECFLAGS))
 ifeq ($(strip $(DOPIC)),y)
 SAFECFLAGS+=-fPIC
 endif
+ifeq ($(strip $(UCLIBC_PROFILING)),y)
+SAFECFLAGS+=-DGMON_SUPPORT
+endif
 
 OBJ=$(COBJS) $(MOBJ)
 
diff --git a/libc/sysdeps/linux/common/bits/atomicity.h b/libc/sysdeps/linux/common/bits/atomicity.h
new file mode 100644
index 000000000..1a756498b
--- /dev/null
+++ b/libc/sysdeps/linux/common/bits/atomicity.h
@@ -0,0 +1,54 @@
+/* Low-level functions for atomic operations.  Stub version.
+   Copyright (C) 1997,2001 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, write to the Free
+   Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
+   02111-1307 USA.  */
+
+#ifndef _ATOMICITY_H
+#define _ATOMICITY_H	1
+
+#include <inttypes.h>
+
+#warning stub atomicity functions are not really atomic
+
+static inline int
+__attribute__ ((unused))
+exchange_and_add (volatile uint32_t *mem, int val)
+{
+  int result = *mem;
+  *mem += val;
+  return result;
+}
+
+static inline void
+__attribute__ ((unused))
+atomic_add (volatile uint32_t *mem, int val)
+{
+  *mem += val;
+}
+
+static inline int
+__attribute__ ((unused))
+compare_and_swap (volatile long int *p, long int oldval, long int newval)
+{
+  if (*p != oldval)
+    return 0;
+
+  *p = newval;
+  return 1;
+}
+
+#endif /* atomicity.h */
diff --git a/libc/sysdeps/linux/common/bits/machine-gmon.h b/libc/sysdeps/linux/common/bits/machine-gmon.h
new file mode 100644
index 000000000..eb046b068
--- /dev/null
+++ b/libc/sysdeps/linux/common/bits/machine-gmon.h
@@ -0,0 +1,54 @@
+/* Machine-dependent definitions for profiling support.  Generic GCC 2 version.
+   Copyright (C) 1996, 1997, 2000 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, write to the Free
+   Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
+   02111-1307 USA.  */
+
+/* GCC version 2 gives us a perfect magical function to get
+   just the information we need:
+     void *__builtin_return_address (unsigned int N)
+   returns the return address of the frame N frames up.  */
+
+/* Be warned that GCC cannot usefully compile __builtin_return_address(N)
+   for N != 0 on all machines.  In this case, you may have to write
+   your own version of _mcount().  */
+
+#if __GNUC__ < 2
+ #error "This file uses __builtin_return_address, a GCC 2 extension."
+#endif
+
+#include <sysdep.h>
+#ifndef NO_UNDERSCORES
+/* The asm symbols for C functions are `_function'.
+   The canonical name for the counter function is `mcount', no _.  */
+void _mcount (void) asm ("mcount");
+#else
+/* The canonical name for the function is `_mcount' in both C and asm,
+   but some old asm code might assume it's `mcount'.  */
+void _mcount (void);
+weak_alias (_mcount, mcount)
+#endif
+
+static void mcount_internal (u_long frompc, u_long selfpc);
+
+#define _MCOUNT_DECL(frompc, selfpc) \
+static inline void mcount_internal (u_long frompc, u_long selfpc)
+
+#define MCOUNT \
+void _mcount (void)							      \
+{									      \
+  mcount_internal ((u_long) RETURN_ADDRESS (1), (u_long) RETURN_ADDRESS (0)); \
+}
diff --git a/libc/sysdeps/linux/common/bits/profil-counter.h b/libc/sysdeps/linux/common/bits/profil-counter.h
new file mode 100644
index 000000000..9cae5840d
--- /dev/null
+++ b/libc/sysdeps/linux/common/bits/profil-counter.h
@@ -0,0 +1,27 @@
+/* Machine-dependent SIGPROF signal handler.  "Generic" version w/ sigcontext
+   Copyright (C) 1996, 1997 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, write to the Free
+   Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
+   02111-1307 USA.  */
+
+/* In many Unix systems signal handlers are called like this
+   and the interrupted PC is easily findable in the `struct sigcontext'.  */
+
+static void
+profil_counter (int signr, int code, struct sigcontext *scp)
+{
+  profil_count ((void *) scp->sc_pc);
+}
diff --git a/libc/sysdeps/linux/common/bits/sigcontextinfo.h b/libc/sysdeps/linux/common/bits/sigcontextinfo.h
new file mode 100644
index 000000000..40305b488
--- /dev/null
+++ b/libc/sysdeps/linux/common/bits/sigcontextinfo.h
@@ -0,0 +1,27 @@
+/* Copyright (C) 1998, 1999 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+   Contributed by Ulrich Drepper <drepper@cygnus.com>, 1998.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, write to the Free
+   Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
+   02111-1307 USA.  */
+
+/* In general we cannot provide any information.  */
+#define SIGCONTEXT struct sigcontext *
+#define SIGCONTEXT_EXTRA_ARGS
+#define GET_PC(ctx)	((void *) 0)
+#define GET_FRAME(ctx)	((void *) 0)
+#define GET_STACK(ctx)	((void *) 0)
+#define CALL_SIGHANDLER(handler, signo, ctx) \
+  (handler)((signo), SIGCONTEXT_EXTRA_ARGS (ctx))
diff --git a/libc/sysdeps/linux/common/bits/stackinfo.h b/libc/sysdeps/linux/common/bits/stackinfo.h
new file mode 100644
index 000000000..1ed7b9503
--- /dev/null
+++ b/libc/sysdeps/linux/common/bits/stackinfo.h
@@ -0,0 +1,34 @@
+/* Copyright (C) 1999 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, write to the Free
+   Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
+   02111-1307 USA.  */
+
+/* This file contains a bit of information about the stack allocation
+   of the processor.  Since there is no general truth we can't say
+   anything here.  */
+
+#ifndef _STACKINFO_H
+#define _STACKINFO_H	1
+
+#error Machine stack direction unknown.
+#if 0
+#define _STACK_GROWS_DOWN	1
+#define _STACK_GROWS_UP		1
+#endif
+
+#endif	/* stackinfo.h */
+
+
diff --git a/libc/sysdeps/linux/common/gmon-start.c b/libc/sysdeps/linux/common/gmon-start.c
new file mode 100644
index 000000000..6878a7a71
--- /dev/null
+++ b/libc/sysdeps/linux/common/gmon-start.c
@@ -0,0 +1,58 @@
+/* Code to enable profiling at program startup.
+   Copyright (C) 1995,1996,1997,2000,2001,2002 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, write to the Free
+   Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
+   02111-1307 USA.  */
+
+#include <features.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <sys/types.h>
+#include <sys/gmon.h>
+
+#ifdef __UCLIBC_PROFILING__
+
+/* Beginning and end of our code segment. We cannot declare them
+   as the external functions since we want the addresses of those
+   labels. Taking the address of a function may have different
+   meanings on different platforms. */
+
+extern void _start;
+extern void etext;
+
+
+void __gmon_start__ (void)
+{
+#ifdef __UCLIBC_CTOR_DTOR__
+    /* Protect from being called more than once.  Since crti.o is linked
+       into every shared library, each of their init functions will call us.  */
+    static int called;
+
+    if (called)
+	return;
+
+    called = 1;
+#endif
+
+    /* Start keeping profiling records.  */
+    monstartup ((u_long) &_start, (u_long) &etext);
+
+    /* Call _mcleanup before exiting; it will write out gmon.out from the
+       collected data.  */
+    atexit (&_mcleanup);
+}
+#endif
+
diff --git a/libc/sysdeps/linux/common/gmon.c b/libc/sysdeps/linux/common/gmon.c
new file mode 100644
index 000000000..b3fe788f7
--- /dev/null
+++ b/libc/sysdeps/linux/common/gmon.c
@@ -0,0 +1,641 @@
+/*-
+ * 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.
+ * 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 <features.h>
+#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 <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+#include <signal.h>
+#include <sys/time.h>
+#include <sys/types.h>
+
+#ifdef __UCLIBC_PROFILING__
+
+/*  Head of basic-block list or NULL. */
+struct __bb *__bb_head;
+
+struct gmonparam _gmonparam = { GMON_PROF_OFF };
+
+/*
+ * See profil(2) where this is described:
+ */
+static int	s_scale;
+#define		SCALE_1_TO_1	0x10000L
+
+#define ERR(s) write (STDERR_FILENO, s, sizeof (s) - 1)
+
+void moncontrol __P ((int mode));
+static void write_hist __P ((int fd));
+static void write_call_graph __P ((int fd));
+static void write_bb_counts __P ((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;
+
+    /* Don't change the state if we ran into an error.  */
+    if (p->state == GMON_PROF_ERROR)
+	return;
+
+    if (mode)
+    {
+	/* start */
+	profil((void *) p->kcount, p->kcountsize, p->lowpc, s_scale);
+	p->state = GMON_PROF_ON;
+    }
+    else
+    {
+	/* stop */
+	profil(NULL, 0, 0, 0);
+	p->state = GMON_PROF_OFF;
+    }
+}
+
+
+void monstartup (u_long lowpc, u_long highpc)
+{
+    register 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->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 = 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 = 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);
+}
+
+
+/* Return frequency of ticks reported by profil. */
+static int profile_frequency (void)
+{
+    /*
+     * Discover the tick frequency of the machine if something goes wrong,
+     * we return 0, an impossible hertz.
+     */
+    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);
+}
+
+
+static void write_hist (int fd)
+{
+    u_char tag = GMON_TAG_TIME_HIST;
+    struct gmon_hist_hdr thdr __attribute__ ((aligned (__alignof__ (char *))));
+
+    if (_gmonparam.kcountsize > 0)
+    {
+	struct iovec iov[3] =
+	{
+	    { &tag, sizeof (tag) },
+	    { &thdr, sizeof (struct gmon_hist_hdr) },
+	    { _gmonparam.kcount, _gmonparam.kcountsize }
+	};
+
+	*(char **) thdr.low_pc = (char *) _gmonparam.lowpc;
+	*(char **) thdr.high_pc = (char *) _gmonparam.highpc;
+	*(int32_t *) thdr.hist_size = (_gmonparam.kcountsize
+		/ sizeof (HISTCOUNTER));
+	*(int32_t *) thdr.prof_rate = profile_frequency ();
+	strncpy (thdr.dimen, "seconds", sizeof (thdr.dimen));
+	thdr.dimen_abbrev = 's';
+
+	writev (fd, iov, 3);
+    }
+}
+
+
+static void write_call_graph (int fd)
+{
+#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;
+    int 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;
+	    arc.selfpc = (char *) _gmonparam.tos[to_index].selfpc;
+	    arc.count  = _gmonparam.tos[to_index].count;
+	    memcpy (raw_arc + nfilled, &arc, sizeof (raw_arc [0]));
+
+	    if (++nfilled == NARCS_PER_WRITEV)
+	    {
+		writev (fd, iov, 2 * nfilled);
+		nfilled = 0;
+	    }
+	}
+    }
+    if (nfilled > 0)
+	writev (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 (fd, bbhead, 2);
+	for (nfilled = i = 0; i < ncounts; ++i)
+	{
+	    if (nfilled > (sizeof (bbbody) / sizeof (bbbody[0])) - 2)
+	    {
+		writev (fd, bbbody, nfilled);
+		nfilled = 0;
+	    }
+
+	    bbbody[nfilled++].iov_base = (char *) &grp->addresses[i];
+	    bbbody[nfilled++].iov_base = &grp->counts[i];
+	}
+	if (nfilled > 0)
+	    writev (fd, bbbody, nfilled);
+    }
+}
+
+
+static void write_gmon (void)
+{
+    struct gmon_hdr ghdr __attribute__ ((aligned (__alignof__ (int))));
+    int fd = -1;
+    char *env;
+
+#ifndef O_NOFOLLOW
+# define O_NOFOLLOW	0
+#endif
+
+    env = getenv ("GMON_OUT_PREFIX");
+    if (env != NULL 
+#if 0
+	    && !__libc_enable_secure
+#endif
+	    )
+    {
+	size_t len = strlen (env);
+	char buf[len + 20];
+	sprintf (buf, "%s.%u", env, getpid ());
+	fd = open (buf, O_CREAT|O_TRUNC|O_WRONLY|O_NOFOLLOW, 0666);
+    }
+
+    if (fd == -1)
+    {
+	fd = open ("gmon.out", O_CREAT|O_TRUNC|O_WRONLY|O_NOFOLLOW, 0666);
+	if (fd < 0)
+	{
+	    char buf[300];
+	    int errnum = errno;
+	    fprintf (stderr, "_mcleanup: gmon.out: %s\n",
+		    strerror_r (errnum, buf, sizeof buf));
+	    return;
+	}
+    }
+
+    /* write gmon.out header: */
+    memset (&ghdr, '\0', sizeof (struct gmon_hdr));
+    memcpy (&ghdr.cookie[0], GMON_MAGIC, sizeof (ghdr.cookie));
+    *(int32_t *) ghdr.version = GMON_VERSION;
+    write (fd, &ghdr, sizeof (struct gmon_hdr));
+
+    /* write PC histogram: */
+    write_hist (fd);
+
+    /* write call-graph: */
+    write_call_graph (fd);
+
+    /* write basic-block execution counts: */
+    write_bb_counts (fd);
+
+    close (fd);
+}
+
+
+void write_profiling (void)
+{
+    int save = _gmonparam.state;
+    _gmonparam.state = GMON_PROF_OFF;
+    if (save == GMON_PROF_ON)
+	write_gmon ();
+    _gmonparam.state = save;
+}
+
+
+void _mcleanup (void)
+{
+    moncontrol (0);
+
+    if (_gmonparam.state != GMON_PROF_ERROR)
+	write_gmon ();
+
+    /* free the memory. */
+    if (_gmonparam.tos != NULL)
+	free (_gmonparam.tos);
+}
+
+#ifndef SIGPROF
+
+/* Enable statistical profiling, writing samples of the PC into at most
+   SIZE bytes of SAMPLE_BUFFER; every processor clock tick while profiling
+   is enabled, the system examines the user PC and increments
+   SAMPLE_BUFFER[((PC - OFFSET) / 2) * SCALE / 65536].  If SCALE is zero,
+   disable profiling.  Returns zero on success, -1 on error.  */
+
+int profil (u_short *sample_buffer, size_t size, size_t offset, u_int scale)
+{
+    if (scale == 0)
+	/* Disable profiling.  */
+	return 0;
+
+    __set_errno (ENOSYS);
+    return -1;
+}
+
+#else
+
+static u_short *samples;
+static size_t nsamples;
+static size_t pc_offset;
+static u_int pc_scale;
+
+static inline void profil_count (void *pc)
+{
+    size_t i = (pc - pc_offset - (void *) 0) / 2;
+
+    if (sizeof (unsigned long long int) > sizeof (size_t))
+	i = (unsigned long long int) i * pc_scale / 65536;
+    else
+	i = i / 65536 * pc_scale + i % 65536 * pc_scale / 65536;
+
+    if (i < nsamples)
+	++samples[i];
+}
+
+/* Get the machine-dependent definition of `profil_counter', the signal
+   handler for SIGPROF.  It calls `profil_count' (above) with the PC of the
+   interrupted code.  */
+#include <bits/profil-counter.h>
+
+/* Enable statistical profiling, writing samples of the PC into at most
+   SIZE bytes of SAMPLE_BUFFER; every processor clock tick while profiling
+   is enabled, the system examines the user PC and increments
+   SAMPLE_BUFFER[((PC - OFFSET) / 2) * SCALE / 65536].  If SCALE is zero,
+   disable profiling.  Returns zero on success, -1 on error.  */
+
+int profil (u_short *sample_buffer, size_t size, size_t offset, u_int scale)
+{
+    static struct sigaction oact;
+    static struct itimerval otimer;
+    struct sigaction act;
+    struct itimerval timer;
+
+    if (sample_buffer == NULL)
+    {
+	/* Disable profiling.  */
+	if (samples == NULL)
+	    /* Wasn't turned on.  */
+	    return 0;
+
+	if (setitimer (ITIMER_PROF, &otimer, NULL) < 0)
+	    return -1;
+	samples = NULL;
+	return sigaction (SIGPROF, &oact, NULL);
+    }
+
+    if (samples)
+    {
+	/* Was already turned on.  Restore old timer and signal handler
+	   first.  */
+	if (setitimer (ITIMER_PROF, &otimer, NULL) < 0
+		|| sigaction (SIGPROF, &oact, NULL) < 0)
+	    return -1;
+    }
+
+    samples = sample_buffer;
+    nsamples = size / sizeof *samples;
+    pc_offset = offset;
+    pc_scale = scale;
+
+    act.sa_handler = (__sighandler_t) &profil_counter;
+    act.sa_flags = SA_RESTART;
+    __sigfillset (&act.sa_mask);
+    if (sigaction (SIGPROF, &act, &oact) < 0)
+	return -1;
+
+    timer.it_value.tv_sec = 0;
+    timer.it_value.tv_usec = 1;
+    timer.it_interval = timer.it_value;
+    return setitimer (ITIMER_PROF, &timer, &otimer);
+}
+
+#endif
+
+
+/* This file provides the machine-dependent definitions of the _MCOUNT_DECL
+   and MCOUNT macros.  */
+#include <bits/machine-gmon.h>
+#include <bits/atomicity.h>
+
+/*
+ * mcount is called on entry to each function compiled with the profiling
+ * switch set.  _mcount(), which is declared in a machine-dependent way
+ * with _MCOUNT_DECL, does the actual work and is either inlined into a
+ * C routine or called by an assembly stub.  In any case, this magic is
+ * taken care of by the MCOUNT definition in <machine/profile.h>.
+ *
+ * _mcount updates data structures that represent traversals of the
+ * program's call graph edges.  frompc and selfpc are the return
+ * address and function address that represents the given call graph edge.
+ *
+ * Note: the original BSD code used the same variable (frompcindex) for
+ * both frompcindex and frompc.  Any reasonable, modern compiler will
+ * perform this optimization.
+ */
+_MCOUNT_DECL(frompc, selfpc)	/* _mcount; may be static, inline, etc */
+{
+	register ARCINDEX *frompcindex;
+	register struct tostruct *top, *prevtop;
+	register struct gmonparam *p;
+	register ARCINDEX toindex;
+	int i;
+
+	p = &_gmonparam;
+	/*
+	 * check that we are profiling
+	 * and that we aren't recursively invoked.
+	 */
+	if (! compare_and_swap (&p->state, GMON_PROF_ON, GMON_PROF_BUSY))
+	  return;
+
+	/*
+	 * check that frompcindex is a reasonable pc value.
+	 * for example:	signal catchers get called from the stack,
+	 *		not from text space.  too bad.
+	 */
+	frompc -= p->lowpc;
+	if (frompc > p->textsize)
+		goto done;
+
+	/* The following test used to be
+		if (p->log_hashfraction >= 0)
+	   But we can simplify this if we assume the profiling data
+	   is always initialized by the functions in gmon.c.  But
+	   then it is possible to avoid a runtime check and use the
+	   smae `if' as in gmon.c.  So keep these tests in sync.  */
+	if ((HASHFRACTION & (HASHFRACTION - 1)) == 0) {
+	  /* avoid integer divide if possible: */
+	    i = frompc >> p->log_hashfraction;
+	} else {
+	    i = frompc / (p->hashfraction * sizeof(*p->froms));
+	}
+	frompcindex = &p->froms[i];
+	toindex = *frompcindex;
+	if (toindex == 0) {
+		/*
+		 *	first time traversing this arc
+		 */
+		toindex = ++p->tos[0].link;
+		if (toindex >= p->tolimit)
+			/* halt further profiling */
+			goto overflow;
+
+		*frompcindex = toindex;
+		top = &p->tos[toindex];
+		top->selfpc = selfpc;
+		top->count = 1;
+		top->link = 0;
+		goto done;
+	}
+	top = &p->tos[toindex];
+	if (top->selfpc == selfpc) {
+		/*
+		 * arc at front of chain; usual case.
+		 */
+		top->count++;
+		goto done;
+	}
+	/*
+	 * have to go looking down chain for it.
+	 * top points to what we are looking at,
+	 * prevtop points to previous top.
+	 * we know it is not at the head of the chain.
+	 */
+	for (; /* goto done */; ) {
+		if (top->link == 0) {
+			/*
+			 * top is end of the chain and none of the chain
+			 * had top->selfpc == selfpc.
+			 * so we allocate a new tostruct
+			 * and link it to the head of the chain.
+			 */
+			toindex = ++p->tos[0].link;
+			if (toindex >= p->tolimit)
+				goto overflow;
+
+			top = &p->tos[toindex];
+			top->selfpc = selfpc;
+			top->count = 1;
+			top->link = *frompcindex;
+			*frompcindex = toindex;
+			goto done;
+		}
+		/*
+		 * otherwise, check the next arc on the chain.
+		 */
+		prevtop = top;
+		top = &p->tos[top->link];
+		if (top->selfpc == selfpc) {
+			/*
+			 * there it is.
+			 * increment its count
+			 * move it to the head of the chain.
+			 */
+			top->count++;
+			toindex = prevtop->link;
+			prevtop->link = top->link;
+			top->link = *frompcindex;
+			*frompcindex = toindex;
+			goto done;
+		}
+
+	}
+done:
+	p->state = GMON_PROF_ON;
+	return;
+overflow:
+	p->state = GMON_PROF_ERROR;
+	return;
+}
+
+/*
+ * Actual definition of mcount function.  Defined in <machine/profile.h>,
+ * which is included by <sys/gmon.h>.
+ */
+MCOUNT
+
+#endif
+
diff --git a/libc/sysdeps/linux/common/initfini.c b/libc/sysdeps/linux/common/initfini.c
index 64fdf6eb4..ba4d68fc9 100644
--- a/libc/sysdeps/linux/common/initfini.c
+++ b/libc/sysdeps/linux/common/initfini.c
@@ -38,7 +38,6 @@
 
 #include <features.h>
 
-#undef GMON_SUPPORT
 
 /* We use embedded asm for .section unconditionally, as this makes it
    easier to insert the necessary directives into crtn.S. */
@@ -87,6 +86,7 @@ dummy (void (*foo) (void))
 asm ("\n/*@_init_PROLOG_BEGINS*/");
 
 #ifdef GMON_SUPPORT
+asm ("\n/*@_init_GMON_STUFF_BEGINS*/");
 static void
 call_gmon_start(void)
 {
@@ -96,6 +96,7 @@ call_gmon_start(void)
   if (gmon_start)
     gmon_start ();
 }
+asm ("\n/*@_init_GMON_STUFF_PAUSES*/");
 #endif
 
 SECTION (".init")
@@ -106,6 +107,7 @@ extern void _init (void);
 void _init (void)
 {
 #ifdef GMON_SUPPORT
+asm ("\n/*@_init_GMON_STUFF_UNPAUSES*/");
   /* We cannot use the normal constructor mechanism in gcrt1.o because it
      appears before crtbegin.o in the link, so the header elt of .ctors
      would come after the elt for __gmon_start__.  One approach is for
@@ -113,6 +115,7 @@ void _init (void)
      module which has a constructor; but then user code's constructors
      would come first, and not be profiled.  */
   call_gmon_start ();
+asm ("\n/*@_init_GMON_STUFF_ENDS*/");
 #else
   asm ("\n/*@_init_PROLOG_PAUSES*/");
   {