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

   1 /* Copyright (C) 2001-2015 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 #ifdef SHARED
  19 /* Redefine time so that the compiler won't complain about the type
  20    mismatch with the IFUNC selector in strong_alias, below.  */
  21 #undef time
  22 #define time __redirect_time
  23 #include <time.h>
  24
  25 #include <dl-vdso.h>
  26
  27 #define VSYSCALL_ADDR_vtime     0xffffffffff600400
  28
  29 /* Avoid DWARF definition DIE on ifunc symbol so that GDB can handle
  30    ifunc symbol properly.  */
  31 extern __typeof (__redirect_time) __libc_time;
  32 void *time_ifunc (void) __asm__ ("__libc_time");
  33
  34 void *
  35 time_ifunc (void)
  36 {
  37   PREPARE_VERSION (linux26, "LINUX_2.6", 61765110);
  38
  39   /* If the vDSO is not available we fall back on the old vsyscall.  */
  40   return _dl_vdso_vsym ("__vdso_time", &linux26) ?: (void *) VSYSCALL_ADDR_vtime;
  41 }
  42 __asm (".type __libc_time, %gnu_indirect_function");
  43
  44 #undef time
  45 strong_alias (__libc_time, time)
  46 libc_hidden_ver (__libc_time, time)
  47
  48 #else
  49
  50 # include <time.h>
  51 # include <sysdep.h>
  52
  53 time_t
  54 time (time_t *t)
  55 {
  56   INTERNAL_SYSCALL_DECL (err);
  57   return INTERNAL_SYSCALL (time, err, 1, t);
  58 }
  59
  60 #endif