glibc/csu/gmon-start.c

86 lines
3.1 KiB
C

/* Code to enable profiling at program startup.
Copyright (C) 1995-2023 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.
In addition to the permissions in the GNU Lesser General Public
License, the Free Software Foundation gives you unlimited
permission to link the compiled version of this file with other
programs, and to distribute those programs without any restriction
coming from the use of this file. (The GNU Lesser General Public
License restrictions do apply in other respects; for example, they
cover modification of the file, and distribution when not linked
into another program.)
Note that people who make modified versions of this file are not
obligated to grant this special exception for their modified
versions; it is their choice whether to do so. The GNU Lesser
General Public License gives permission to release a modified
version without this exception; this exception also makes it
possible to release a modified version which carries forward this
exception.
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 <sys/gmon.h>
#include <stdlib.h>
#include <unistd.h>
#include <elf-initfini.h>
/* Use __executable_start as the lowest address to keep profiling records
if it provided by the linker. */
extern const char __executable_start[] __attribute__ ((visibility ("hidden")));
extern char etext[];
#if !ELF_INITFINI
/* Instead of defining __gmon_start__ globally in gcrt1.o, we make it
static and just put a pointer to it into the .preinit_array
section. */
# define GMON_START_ARRAY_SECTION ".preinit_array"
#endif
#ifdef GMON_START_ARRAY_SECTION
static void __gmon_start__ (void);
static void (*const gmon_start_initializer) (void)
__attribute__ ((used, section (GMON_START_ARRAY_SECTION))) = &__gmon_start__;
static
#else
/* We cannot use the normal constructor mechanism to call
__gmon_start__ because gcrt1.o appears before crtbegin.o in the link.
Instead crti.o calls it specially. */
extern void __gmon_start__ (void);
#endif
void
__gmon_start__ (void)
{
/* 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;
/* Start keeping profiling records. */
__monstartup ((u_long) &__executable_start, (u_long) &etext);
/* Call _mcleanup before exiting; it will write out gmon.out from the
collected data. */
atexit (&_mcleanup);
}