sysdeps/unix/sysv/linux/x86_64/gettimeofday.c

   1 /* Copyright (C) 2002-2014 Free Software Foundation, Inc.
   2    This file is part of the GNU C Library.
   3
   4    The GNU C Library is free software; you can redistribute it and/or
   5    modify it under the terms of the GNU Lesser General Public
   6    License as published by the Free Software Foundation; either
   7    version 2.1 of the License, or (at your option) any later version.
   8
   9    The GNU C Library is distributed in the hope that it will be useful,
  10    but WITHOUT ANY WARRANTY; without even the implied warranty of
  11    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  12    Lesser General Public License for more details.
  13
  14    You should have received a copy of the GNU Lesser General Public
  15    License along with the GNU C Library; if not, see
  16    <http://www.gnu.org/licenses/>.  */
  17
  18 #include <sys/time.h>
  19
  20 #ifdef SHARED
  21
  22 # include <dl-vdso.h>
  23
  24 # define VSYSCALL_ADDR_vgettimeofday    0xffffffffff600000ul
  25
  26 void *gettimeofday_ifunc (void) __asm__ ("__gettimeofday");
  27
  28 void *
  29 gettimeofday_ifunc (void)
  30 {
  31   PREPARE_VERSION (linux26, "LINUX_2.6", 61765110);
  32
  33   /* If the vDSO is not available we fall back on the old vsyscall.  */
  34   return (_dl_vdso_vsym ("__vdso_gettimeofday", &linux26)
  35           ?: (void *) VSYSCALL_ADDR_vgettimeofday);
  36 }
  37 asm (".type __gettimeofday, %gnu_indirect_function");
  38
  39 /* This is doing "libc_hidden_def (__gettimeofday)" but the compiler won't
  40    let us do it in C because it doesn't know we're defining __gettimeofday
  41    here in this file.  */
  42 asm (".globl __GI___gettimeofday\n"
  43      "__GI___gettimeofday = __gettimeofday");
  44
  45 #else
  46
  47 # include <sysdep.h>
  48 # include <errno.h>
  49
  50 int
  51 __gettimeofday (struct timeval *tv, struct timezone *tz)
  52 {
  53   return INLINE_SYSCALL (gettimeofday, 2, tv, tz);
  54 }
  55 libc_hidden_def (__gettimeofday)
  56
  57 #endif
  58 weak_alias (__gettimeofday, gettimeofday)
  59 libc_hidden_weak (gettimeofday)