Add x86 32 bit vDSO time function support

Linux 3.15 adds support for clock_gettime, gettimeofday, and time vDSO
(commit id 37c975545ec63320789962bf307f000f08fabd48).  This patch adds
GLIBC supports to use such symbol when they are avaiable.

Along with x86 vDSO support, this patch cleanup x86_64 code by moving
all common code to x86 common folder.  Only init-first.c is different
between implementations.

1 files changed, 54 insertions, 0 deletions

diff --git a/sysdeps/unix/sysv/linux/x86/gettimeofday.c b/sysdeps/unix/sysv/linux/x86/gettimeofday.c
new file mode 100644
index 0000000000..c820fd767b
--- /dev/null
+++ b/sysdeps/unix/sysv/linux/x86/gettimeofday.c
@@ -0,0 +1,54 @@
+/* gettimeofday - get the time.  Linux/x86 version.
+   Copyright (C) 2015 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <http://www.gnu.org/licenses/>.  */
+
+#include <sys/time.h>
+
+#ifdef SHARED
+
+# include <dl-vdso.h>
+
+void *gettimeofday_ifunc (void) __asm__ ("__gettimeofday");
+
+void *
+gettimeofday_ifunc (void)
+{
+  PREPARE_VERSION_KNOWN (linux26, LINUX_2_6);
+
+  /* If the vDSO is not available we fall back on the old vsyscall.  */
+  return (_dl_vdso_vsym ("__vdso_gettimeofday", &linux26)
+	  ?: GETTIMEOFAY_FALLBACK);
+}
+asm (".type __gettimeofday, %gnu_indirect_function");
+
+libc_ifunc_hidden_def(__gettimeofday)
+
+#else
+
+# include <sysdep.h>
+# include <errno.h>
+
+int
+__gettimeofday (struct timeval *tv, struct timezone *tz)
+{
+  return INLINE_SYSCALL (gettimeofday, 2, tv, tz);
+}
+libc_hidden_def (__gettimeofday)
+
+#endif
+weak_alias (__gettimeofday, gettimeofday)
+libc_hidden_weak (gettimeofday)