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/* Low-level statistical profiling support function. Mostly POSIX.1 version.
Copyright (C) 1996-2024 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, see
<https://www.gnu.org/licenses/>. */
#include <sys/types.h>
#include <unistd.h>
#include <errno.h>
#include <signal.h>
#include <sys/time.h>
#include <stdint.h>
#include <libc-internal.h>
#include <sigsetops.h>
#ifndef SIGPROF
#include <gmon/profil.c>
#else
static u_short *samples;
static size_t nsamples;
static size_t pc_offset;
static u_int pc_scale;
static inline void
profil_count (uintptr_t pc)
{
size_t i = (pc - pc_offset) / 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 "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)
{
struct sigaction act;
struct itimerval timer;
#if !IS_IN (rtld)
static struct sigaction oact;
static struct itimerval otimer;
# define oact_ptr &oact
# define otimer_ptr &otimer
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;
}
#else
/* In ld.so profiling should never be disabled once it runs. */
//assert (sample_buffer != NULL);
# define oact_ptr NULL
# define otimer_ptr NULL
#endif
samples = sample_buffer;
nsamples = size / sizeof *samples;
pc_offset = offset;
pc_scale = scale;
#ifdef SA_SIGINFO
act.sa_sigaction = __profil_counter;
act.sa_flags = SA_SIGINFO;
#else
act.sa_handler = __profil_counter;
act.sa_flags = 0;
#endif
act.sa_flags |= SA_RESTART;
__sigfillset (&act.sa_mask);
if (__sigaction (SIGPROF, &act, oact_ptr) < 0)
return -1;
timer.it_value.tv_sec = 0;
timer.it_value.tv_usec = 1000000 / __profile_frequency ();
timer.it_interval = timer.it_value;
return __setitimer (ITIMER_PROF, &timer, otimer_ptr);
}
weak_alias (__profil, profil)
#endif
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