sysdeps/unix/sysv/linux/x86_64/init-first.c

   1 /* Initialization code run first thing by the ELF startup code.  Linux/x86-64.
   2    Copyright (C) 2007-2015 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 #ifdef SHARED
  20 # include <time.h>
  21 # include <sysdep.h>
  22 # include <dl-vdso.h>
  23 # include <libc-vdso.h>
  24
  25 long int (*VDSO_SYMBOL(clock_gettime)) (clockid_t, struct timespec *)
  26   attribute_hidden;
  27 long int (*VDSO_SYMBOL(getcpu)) (unsigned *, unsigned *, void *)
  28   attribute_hidden;
  29
  30 extern long int __syscall_clock_gettime (clockid_t, struct timespec *);
  31
  32
  33 static inline void
  34 __vdso_platform_setup (void)
  35 {
  36   PREPARE_VERSION (linux26, "LINUX_2.6", 61765110);
  37
  38   void *p = _dl_vdso_vsym ("__vdso_clock_gettime", &linux26);
  39   if (p == NULL)
  40     p = __syscall_clock_gettime;
  41   PTR_MANGLE (p);
  42   VDSO_SYMBOL(clock_gettime) = p;
  43
  44   p = _dl_vdso_vsym ("__vdso_getcpu", &linux26);
  45   /* If the vDSO is not available we fall back on the old vsyscall.  */
  46 #define VSYSCALL_ADDR_vgetcpu   0xffffffffff600800
  47   if (p == NULL)
  48     p = (void *) VSYSCALL_ADDR_vgetcpu;
  49   PTR_MANGLE (p);
  50   VDSO_SYMBOL(getcpu) = p;
  51 }
  52
  53 # define VDSO_SETUP __vdso_platform_setup
  54 #endif
  55
  56 #include <csu/init-first.c>