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

   1 /* Copyright (C) 2005-2015 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
  19 #include <sys/time.h>
  20
  21 #ifdef SHARED
  22
  23 # include <dl-vdso.h>
  24 # include <bits/libc-vdso.h>
  25 # include <dl-machine.h>
  26
  27 void *gettimeofday_ifunc (void) __asm__ ("__gettimeofday");
  28
  29 static int
  30 __gettimeofday_syscall (struct timeval *tv, struct timezone *tz)
  31 {
  32   return INLINE_SYSCALL (gettimeofday, 2, tv, tz);
  33 }
  34
  35 void *
  36 gettimeofday_ifunc (void)
  37 {
  38   PREPARE_VERSION (linux2615, "LINUX_2.6.15", 123718565);
  39
  40   /* If the vDSO is not available we fall back syscall.  */
  41   void *vdso_gettimeofday = _dl_vdso_vsym ("__kernel_gettimeofday", &linux2615);
  42   return (vdso_gettimeofday ? VDSO_IFUNC_RET (vdso_gettimeofday)
  43           : (void*)__gettimeofday_syscall);
  44 }
  45 asm (".type __gettimeofday, %gnu_indirect_function");
  46
  47 /* This is doing "libc_hidden_def (__gettimeofday)" but the compiler won't
  48    let us do it in C because it doesn't know we're defining __gettimeofday
  49    here in this file.  */
  50 asm (".globl __GI___gettimeofday");
  51
  52 /* __GI___gettimeofday is defined as hidden and for ppc32 it enables the
  53    compiler make a local call (symbol@local) for internal GLIBC usage. It
  54    means the PLT won't be used and the ifunc resolver will be called directly.
  55    For ppc64 a call to a function in another translation unit might use a
  56    different toc pointer thus disallowing direct branchess and making internal
  57    ifuncs calls safe.  */
  58 #ifdef __powerpc64__
  59 asm ("__GI___gettimeofday = __gettimeofday");
  60 #else
  61 int
  62 __gettimeofday_vsyscall (struct timeval *tv, struct timezone *tz)
  63 {
  64   return INLINE_VSYSCALL (gettimeofday, 2, tv, tz);
  65 }
  66 asm ("__GI___gettimeofday = __gettimeofday_vsyscall");
  67 #endif
  68
  69 #else
  70
  71 # include <sysdep.h>
  72 # include <errno.h>
  73
  74 int
  75 __gettimeofday (struct timeval *tv, struct timezone *tz)
  76 {
  77   return INLINE_SYSCALL (gettimeofday, 2, tv, tz);
  78 }
  79 libc_hidden_def (__gettimeofday)
  80
  81 #endif
  82 weak_alias (__gettimeofday, gettimeofday)
  83 libc_hidden_weak (gettimeofday)