csu/gmon-start.c

   1 /* Code to enable profiling at program startup.
   2    Copyright (C) 1995-2013 Free Software Foundation, Inc.
   3    This file is part of the GNU C Library.
   4
   5    The GNU C Library is free software; you can redistribute it and/or
   6    modify it under the terms of the GNU Lesser General Public
   7    License as published by the Free Software Foundation; either
   8    version 2.1 of the License, or (at your option) any later version.
   9
  10    The GNU C Library is distributed in the hope that it will be useful,
  11    but WITHOUT ANY WARRANTY; without even the implied warranty of
  12    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  13    Lesser General Public License for more details.
  14
  15    You should have received a copy of the GNU Lesser General Public
  16    License along with the GNU C Library; if not, see
  17    <http://www.gnu.org/licenses/>.  */
  18
  19 #include <sys/types.h>
  20 #include <sys/gmon.h>
  21 #include <stdlib.h>
  22 #include <unistd.h>
  23 #define __ASSEMBLY__
  24 #include <entry.h>
  25
  26 /* Beginning and end of our code segment. We cannot declare them
  27    as the external functions since we want the addresses of those
  28    labels. Taking the address of a function may have different
  29    meanings on different platforms. */
  30 #ifdef ENTRY_POINT_DECL
  31 ENTRY_POINT_DECL(extern)
  32 #else
  33 extern char ENTRY_POINT[];
  34 #endif
  35 extern char etext[];
  36
  37 #ifndef TEXT_START
  38 # ifdef ENTRY_POINT_DECL
  39 #  define TEXT_START ENTRY_POINT
  40 # else
  41 #  define TEXT_START &ENTRY_POINT
  42 # endif
  43 #endif
  44
  45 /* We cannot use the normal constructor mechanism to call
  46    __gmon_start__ because gcrt1.o appears before crtbegin.o in the link.
  47    Instead crti.o calls it specially.  */
  48 extern void __gmon_start__ (void);
  49
  50 void
  51 __gmon_start__ (void)
  52 {
  53   /* Protect from being called more than once.  Since crti.o is linked
  54      into every shared library, each of their init functions will call us.  */
  55   static int called;
  56
  57   if (called)
  58     return;
  59
  60   called = 1;
  61
  62   /* Start keeping profiling records.  */
  63   __monstartup ((u_long) TEXT_START, (u_long) &etext);
  64
  65   /* Call _mcleanup before exiting; it will write out gmon.out from the
  66      collected data.  */
  67   atexit (&_mcleanup);
  68 }