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_clock_gettime) (clockid_t, struct timespec *)
  26   attribute_hidden;
  27 long int (*__vdso_getcpu) (unsigned *, unsigned *, void *) attribute_hidden;
  28
  29 extern long int __syscall_clock_gettime (clockid_t, struct timespec *);
  30
  31
  32 static inline void
  33 __vdso_platform_setup (void)
  34 {
  35   PREPARE_VERSION (linux26, "LINUX_2.6", 61765110);
  36
  37   void *p = _dl_vdso_vsym ("__vdso_clock_gettime", &linux26);
  38   if (p == NULL)
  39     p = __syscall_clock_gettime;
  40   PTR_MANGLE (p);
  41   __vdso_clock_gettime = p;
  42
  43   p = _dl_vdso_vsym ("__vdso_getcpu", &linux26);
  44   /* If the vDSO is not available we fall back on the old vsyscall.  */
  45 #define VSYSCALL_ADDR_vgetcpu   0xffffffffff600800
  46   if (p == NULL)
  47     p = (void *) VSYSCALL_ADDR_vgetcpu;
  48   PTR_MANGLE (p);
  49   __vdso_getcpu = p;
  50 }
  51
  52 # define VDSO_SETUP __vdso_platform_setup
  53 #endif
  54
  55 #include <csu/init-first.c>