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, 52 insertions, 0 deletions

diff --git a/sysdeps/unix/sysv/linux/i386/init-first.c b/sysdeps/unix/sysv/linux/i386/init-first.c
new file mode 100644
index 0000000000..4be65d7e47
--- /dev/null
+++ b/sysdeps/unix/sysv/linux/i386/init-first.c
@@ -0,0 +1,52 @@
+/* Initialization code run first thing by the ELF startup code.  Linux/i386.
+   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/>.  */
+
+#ifdef SHARED
+# include <time.h>
+# include <sysdep.h>
+# include <dl-vdso.h>
+# include <libc-vdso.h>
+
+long int (*__vdso_clock_gettime) (clockid_t, struct timespec *)
+  __attribute__ ((nocommon));
+libc_hidden_proto (__vdso_clock_gettime)
+libc_hidden_data_def (__vdso_clock_gettime)
+
+static long int
+clock_gettime_syscall (clockid_t id, struct timespec *tp)
+{
+  INTERNAL_SYSCALL_DECL (err);
+  return INTERNAL_SYSCALL (clock_gettime, err, 2, id, tp);
+}
+
+static inline void
+__vdso_platform_setup (void)
+{
+  PREPARE_VERSION_KNOWN (linux26, LINUX_2_6);
+
+  void *p = _dl_vdso_vsym ("__vdso_clock_gettime", &linux26);
+  if (p == NULL)
+    p = clock_gettime_syscall;
+  PTR_MANGLE (p);
+  __vdso_clock_gettime = p;
+}
+
+# define VDSO_SETUP __vdso_platform_setup
+#endif
+
+#include <csu/init-first.c>