linux: Consolidate Linux gettimeofday

The IFUNC bypass to vDSO is used when USE_IFUNC_GETTIMEOFDAY is set.
Currently aarch64, powerpc*, and x86 defines it.  Otherwise the
generic implementation is used, which calls clock_gettime.

Checked on aarch64-linux-gnu, powerpc64le-linux-gnu,
powerpc64-linux-gnu, powerpc-linux-gnu-power4, x86_64-linux-gnu,
and i686-linux-gnu.

Reviewed-by: Siddhesh Poyarekar <siddhesh@sourceware.org>

1 files changed, 57 insertions, 0 deletions

diff --git a/sysdeps/unix/sysv/linux/gettimeofday.c b/sysdeps/unix/sysv/linux/gettimeofday.c
new file mode 100644
index 0000000000..80d6819e5a
--- /dev/null
+++ b/sysdeps/unix/sysv/linux/gettimeofday.c
@@ -0,0 +1,57 @@
+/* gettimeofday - set time.  Linux version.
+   Copyright (C) 2020 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
+   <https://www.gnu.org/licenses/>.  */
+
+/* Optimize the function call by setting the PLT directly to vDSO symbol.  */
+#ifdef USE_IFUNC_GETTIMEOFDAY
+# include <time.h>
+# include <string.h>
+# include <sysdep.h>
+# include <sysdep-vdso.h>
+
+# ifdef SHARED
+#  include <dl-vdso.h>
+
+static int
+__gettimeofday_syscall (struct timeval *restrict tv, void *restrict tz)
+{
+  if (__glibc_unlikely (tz != 0))
+    memset (tz, 0, sizeof *tz);
+  return INLINE_SYSCALL_CALL (gettimeofday, tv, tz);
+}
+
+# undef INIT_ARCH
+# define INIT_ARCH() \
+  void *vdso_gettimeofday = get_vdso_symbol (HAVE_GETTIMEOFDAY_VSYSCALL)
+libc_ifunc (__gettimeofday,
+	    vdso_gettimeofday ? VDSO_IFUNC_RET (vdso_gettimeofday)
+			      : (void *) __gettimeofday_syscall)
+
+# else
+int
+__gettimeofday (struct timeval *restrict tv, void *restrict tz)
+{
+  if (__glibc_unlikely (tz != 0))
+    memset (tz, 0, sizeof *tz);
+
+  return INLINE_VSYSCALL (gettimeofday, 2, tv, tz);
+}
+# endif
+weak_alias (__gettimeofday, gettimeofday)
+#else /* USE_IFUNC_GETTIMEOFDAY  */
+# include <time/gettimeofday.c>
+#endif