[v2] Add x86 32 bit vDSO time function support

Message ID 5436D48C.2090509@linux.vnet.ibm.com
State Superseded
Headers

Commit Message

Adhemerval Zanella Netto Oct. 9, 2014, 6:31 p.m. UTC
  Hi,

This is a respin of my x86 vDSO cleanup / time support.  The new ftime testcase
showed the initial patch was not really generating correct code for internal
ifunc for i386. Similar to a previous bug that was presented in ppc32, linker
creates an incorrect PLT stub for internal __gettimeofday usage. I tried some
binutils (2.23, 2.24, master), but all show the same behavior. x86_64 is ok,
I checked and ftime does call __gettimeofday from vDSO.

I didn't dig into this issue, so if someone with more experience in i386 ABI
could take a look it will helpful. Currently I'm setting the internal
getimeofday for i386 to its syscall version. 

Checked on i386 and x86_64 on a 3.10 kernel and on a 3.16 kernel.

--

2014-10-09  Adhemerval Zanella  <azanella@linux.vnet.ibm.com>
	    Stefani Seibold  <stefani@seibold.net>

	* sysdeps/unix/sysv/linux/x86_64/Makefile [$(subdir) = elf]
	(sysdep_routines): Add dl-vdso here, ...
	* sysdeps/unix/sysv/linux/x86/Makefile [$(subdir) = elf]
	(sysdep_routines): ... not here.
	* sysdeps/unix/sysv/linux/i386/gettimeofday.c: New file: set syscall
	fallback when vDSO is not presented.
	* sysdeps/unix/sysv/linux/x86_64/init-first.c (__vdso_clock_gettime):
	Define with libc_hidden_proto/libc_hidden_data_def definitions.
	(_libc_vdso_platform_setup): Rename to __vdso_platform_setup.
	* sysdeps/unix/sysv/linux/i386/init-first.c: New file: likewise.
	* sysdeps/unix/sysv/linux/i386/time.c: New file: likewise.
	* sysdeps/unix/sysv/linux/x86_64/bits/libc-vdso.h: Moved to ...
	* sysdeps/unix/sysv/linux/x86/libc-vdso.h: ... here.
	* sysdeps/unix/sysv/linux/x86_64/clock_gettime.c: Move to ...
	* sysdeps/unix/sysv/linux/x86/clock_gettime.c: ... here.
	* sysdeps/unix/sysv/linux/x86_64/gettimeofday.c: Move to ...
	* sysdeps/unix/sysv/linux/x86/gettimeofday.c: ... here.  Also added
	fallback configurable symbol when vDSO is not available.
	* sysdeps/unix/sysv/linux/x86_64/time.c: Move to ...
	* sysdeps/unix/sysv/linux/x86/time.c: ... here.  Also refactored to
	be able to redefine fallback symbol when vDSO is not available.
	* sysdeps/unix/sysv/linux/x86_64/timespec_get.c: Move to ...
	* sysdeps/unix/sysv/linux/x86/timespec_get.c: ... here.
---
  

Comments

Nathan Lynch Oct. 9, 2014, 8:50 p.m. UTC | #1
On 10/09/2014 01:31 PM, Adhemerval Zanella wrote:
> 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 0000000..dc3b1ba
> --- /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) 2014 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 (linux26, "LINUX_2.6", 61765110);

Perhaps:

     PREPARE_VERSION_KNOWN (linux26, LINUX_2_6);

(here and several other places)


> +
> +  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>

[...]

> diff --git a/sysdeps/unix/sysv/linux/x86/clock_gettime.c b/sysdeps/unix/sysv/linux/x86/clock_gettime.c
> new file mode 100644
> index 0000000..2547a8c
> --- /dev/null
> +++ b/sysdeps/unix/sysv/linux/x86/clock_gettime.c
> @@ -0,0 +1,38 @@
> +/* Get the current value of a clock.  Linux/x86 version.
> +   Copyright (C) 2014 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 <libc-vdso.h>
> +
> +#ifdef SHARED
> +# define SYSCALL_GETTIME(id, tp) \
> +  ({ long int (*f) (clockid_t, struct timespec *) = __vdso_clock_gettime; \
> +  long int v_ret;							  \
> +  PTR_DEMANGLE (f);							  \
> +  v_ret = (*f) (id, tp);						  \
> +  if (INTERNAL_SYSCALL_ERROR_P (v_ret, )) {				  \
> +    __set_errno (INTERNAL_SYSCALL_ERRNO (v_ret, ));			  \
> +    v_ret = -1;								  \
> +  }									  \
> +  v_ret; })

Does introducing the dispatch through function pointer here cause a
measurable performance regression on i386 kernels which lack the VDSO?
If so, is that a concern?

When I've tried this approach on ARM, it appears to do so (around 5%
slowdown).


> +# define INTERNAL_GETTIME(id, tp) \
> +  ({ long int (*f) (clockid_t, struct timespec *) = __vdso_clock_gettime; \
> +  PTR_DEMANGLE (f);							  \
> +  (*f) (id, tp); })
> +#endif

I'm probably missing something, but I am failing to see the need for an
INTERNAL_GETTIME definition in
sysdeps/unix/sysv/linux/x86/clock_gettime.c.  I know this patch is
merely moving existing code, but sysdeps/unix/sysv/linux/clock_gettime.c
does not use INTERNAL_GETTIME, and neither does
sysdeps/unix/clock_gettime.c.

INTERNAL_GETTIME is needed for timespec_get, but I am not seeing the
need to duplicate it for clock_gettime.
  
Adhemerval Zanella Netto Nov. 3, 2014, 8:30 p.m. UTC | #2
On 09-10-2014 17:50, Nathan Lynch wrote:
> On 10/09/2014 01:31 PM, Adhemerval Zanella wrote:
>> +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 (linux26, "LINUX_2.6", 61765110);
> Perhaps:
>
>      PREPARE_VERSION_KNOWN (linux26, LINUX_2_6);
>
> (here and several other places)

Thanks, I fixed it on all the places nows.

>
>> +#ifdef SHARED
>> +# define SYSCALL_GETTIME(id, tp) \
>> +  ({ long int (*f) (clockid_t, struct timespec *) = __vdso_clock_gettime; \
>> +  long int v_ret;							  \
>> +  PTR_DEMANGLE (f);							  \
>> +  v_ret = (*f) (id, tp);						  \
>> +  if (INTERNAL_SYSCALL_ERROR_P (v_ret, )) {				  \
>> +    __set_errno (INTERNAL_SYSCALL_ERRNO (v_ret, ));			  \
>> +    v_ret = -1;								  \
>> +  }									  \
>> +  v_ret; })
> Does introducing the dispatch through function pointer here cause a
> measurable performance regression on i386 kernels which lack the VDSO?
> If so, is that a concern?
>
> When I've tried this approach on ARM, it appears to do so (around 5%
> slowdown).

Using a simple benchmark (in attachments) the difference in such scenarios is not
as drastic as ARM it seems:

kernel: Linux birita 3.13.0-39
CPU:    Intel(R) Core(TM)2 CPU          6600  @ 2.40GHz

EGLIBC 2.19-0ubuntu6.3: 1415.12 cycles
GLIBC 2.20 master:      1421.66 cycles

>
>
>> +# define INTERNAL_GETTIME(id, tp) \
>> +  ({ long int (*f) (clockid_t, struct timespec *) = __vdso_clock_gettime; \
>> +  PTR_DEMANGLE (f);							  \
>> +  (*f) (id, tp); })
>> +#endif
> I'm probably missing something, but I am failing to see the need for an
> INTERNAL_GETTIME definition in
> sysdeps/unix/sysv/linux/x86/clock_gettime.c.  I know this patch is
> merely moving existing code, but sysdeps/unix/sysv/linux/clock_gettime.c
> does not use INTERNAL_GETTIME, and neither does
> sysdeps/unix/clock_gettime.c.
>
> INTERNAL_GETTIME is needed for timespec_get, but I am not seeing the
> need to duplicate it for clock_gettime.

i386 does not define HAVE_CLOCK_GETTIME_VSYSCALL and thus:

sysdeps/unix/sysv/linux/clock_gettime.c:

 26: # define INTERNAL_VSYSCALL INTERNAL_SYSCALL

and then if INTERNAL_GETTIME is not defined, it will as:

 37 #ifndef INTERNAL_GETTIME
 38 # define INTERNAL_GETTIME(id, tp) \
 39   INTERNAL_VSYSCALL (clock_gettime, err, 2, id, tp)
 40 #endif

And without proper set the PTR_DEMANGLE is not called either.

With PREPARE_VERSION_KNOWN fixes, is it ok to commit?
  
Adhemerval Zanella Netto Nov. 3, 2014, 9:42 p.m. UTC | #3
On 03-11-2014 18:30, Adhemerval Zanella wrote:
> On 09-10-2014 17:50, Nathan Lynch wrote:
>> On 10/09/2014 01:31 PM, Adhemerval Zanella wrote:
>>> +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 (linux26, "LINUX_2.6", 61765110);
>> Perhaps:
>>
>>      PREPARE_VERSION_KNOWN (linux26, LINUX_2_6);
>>
>> (here and several other places)
> Thanks, I fixed it on all the places nows.
>
>>> +#ifdef SHARED
>>> +# define SYSCALL_GETTIME(id, tp) \
>>> +  ({ long int (*f) (clockid_t, struct timespec *) = __vdso_clock_gettime; \
>>> +  long int v_ret;							  \
>>> +  PTR_DEMANGLE (f);							  \
>>> +  v_ret = (*f) (id, tp);						  \
>>> +  if (INTERNAL_SYSCALL_ERROR_P (v_ret, )) {				  \
>>> +    __set_errno (INTERNAL_SYSCALL_ERRNO (v_ret, ));			  \
>>> +    v_ret = -1;								  \
>>> +  }									  \
>>> +  v_ret; })
>> Does introducing the dispatch through function pointer here cause a
>> measurable performance regression on i386 kernels which lack the VDSO?
>> If so, is that a concern?
>>
>> When I've tried this approach on ARM, it appears to do so (around 5%
>> slowdown).
> Using a simple benchmark (in attachments) the difference in such scenarios is not
> as drastic as ARM it seems:
>
> kernel: Linux birita 3.13.0-39
> CPU:    Intel(R) Core(TM)2 CPU          6600  @ 2.40GHz
>
> EGLIBC 2.19-0ubuntu6.3: 1415.12 cycles
> GLIBC 2.20 master:      1421.66 cycles
>
>>
>>> +# define INTERNAL_GETTIME(id, tp) \
>>> +  ({ long int (*f) (clockid_t, struct timespec *) = __vdso_clock_gettime; \
>>> +  PTR_DEMANGLE (f);							  \
>>> +  (*f) (id, tp); })
>>> +#endif
>> I'm probably missing something, but I am failing to see the need for an
>> INTERNAL_GETTIME definition in
>> sysdeps/unix/sysv/linux/x86/clock_gettime.c.  I know this patch is
>> merely moving existing code, but sysdeps/unix/sysv/linux/clock_gettime.c
>> does not use INTERNAL_GETTIME, and neither does
>> sysdeps/unix/clock_gettime.c.
>>
>> INTERNAL_GETTIME is needed for timespec_get, but I am not seeing the
>> need to duplicate it for clock_gettime.
> i386 does not define HAVE_CLOCK_GETTIME_VSYSCALL and thus:
>
> sysdeps/unix/sysv/linux/clock_gettime.c:
>
>  26: # define INTERNAL_VSYSCALL INTERNAL_SYSCALL
>
> and then if INTERNAL_GETTIME is not defined, it will as:
>
>  37 #ifndef INTERNAL_GETTIME
>  38 # define INTERNAL_GETTIME(id, tp) \
>  39   INTERNAL_VSYSCALL (clock_gettime, err, 2, id, tp)
>  40 #endif
>
> And without proper set the PTR_DEMANGLE is not called either.
>
> With PREPARE_VERSION_KNOWN fixes, is it ok to commit?
>
Send the missing simple benchmark.
  
Nathan Lynch Nov. 3, 2014, 11:51 p.m. UTC | #4
On 11/03/2014 02:30 PM, Adhemerval Zanella wrote:
> On 09-10-2014 17:50, Nathan Lynch wrote:
>> On 10/09/2014 01:31 PM, Adhemerval Zanella wrote:
>>
>>> +#ifdef SHARED
>>> +# define SYSCALL_GETTIME(id, tp) \
>>> +  ({ long int (*f) (clockid_t, struct timespec *) = __vdso_clock_gettime; \
>>> +  long int v_ret;							  \
>>> +  PTR_DEMANGLE (f);							  \
>>> +  v_ret = (*f) (id, tp);						  \
>>> +  if (INTERNAL_SYSCALL_ERROR_P (v_ret, )) {				  \
>>> +    __set_errno (INTERNAL_SYSCALL_ERRNO (v_ret, ));			  \
>>> +    v_ret = -1;								  \
>>> +  }									  \
>>> +  v_ret; })
>> Does introducing the dispatch through function pointer here cause a
>> measurable performance regression on i386 kernels which lack the VDSO?
>> If so, is that a concern?
>>
>> When I've tried this approach on ARM, it appears to do so (around 5%
>> slowdown).
> 
> Using a simple benchmark (in attachments) the difference in such scenarios is not
> as drastic as ARM it seems:
> 
> kernel: Linux birita 3.13.0-39
> CPU:    Intel(R) Core(TM)2 CPU          6600  @ 2.40GHz
> 
> EGLIBC 2.19-0ubuntu6.3: 1415.12 cycles
> GLIBC 2.20 master:      1421.66 cycles

OK.


>>> +# define INTERNAL_GETTIME(id, tp) \
>>> +  ({ long int (*f) (clockid_t, struct timespec *) = __vdso_clock_gettime; \
>>> +  PTR_DEMANGLE (f);							  \
>>> +  (*f) (id, tp); })
>>> +#endif
>> I'm probably missing something, but I am failing to see the need for an
>> INTERNAL_GETTIME definition in
>> sysdeps/unix/sysv/linux/x86/clock_gettime.c.  I know this patch is
>> merely moving existing code, but sysdeps/unix/sysv/linux/clock_gettime.c
>> does not use INTERNAL_GETTIME, and neither does
>> sysdeps/unix/clock_gettime.c.
>>
>> INTERNAL_GETTIME is needed for timespec_get, but I am not seeing the
>> need to duplicate it for clock_gettime.
> 
> i386 does not define HAVE_CLOCK_GETTIME_VSYSCALL and thus:
> 
> sysdeps/unix/sysv/linux/clock_gettime.c:
> 
>  26: # define INTERNAL_VSYSCALL INTERNAL_SYSCALL
> 
> and then if INTERNAL_GETTIME is not defined, it will as:
> 
>  37 #ifndef INTERNAL_GETTIME
>  38 # define INTERNAL_GETTIME(id, tp) \
>  39   INTERNAL_VSYSCALL (clock_gettime, err, 2, id, tp)
>  40 #endif
> 
> And without proper set the PTR_DEMANGLE is not called either.

I think my point might be better expressed as: why is INTERNAL_GETTIME
defined in linux/clock_gettime.c at all?  It is not used in the
clock_gettime implementation.

The only use in glibc of a macro by that name is in
linux/timespec_get.c, and the arch can override it in its own
timespec_get.c (as x86_64 currently does).


> With PREPARE_VERSION_KNOWN fixes, is it ok to commit?

I have no objection, FWIW.
  

Patch

diff --git a/sysdeps/unix/sysv/linux/i386/gettimeofday.c b/sysdeps/unix/sysv/linux/i386/gettimeofday.c
new file mode 100644
index 0000000..2b58fd5
--- /dev/null
+++ b/sysdeps/unix/sysv/linux/i386/gettimeofday.c
@@ -0,0 +1,39 @@ 
+/* gettimeofday - get the time.  Linux/i386 version.
+   Copyright (C) 2014 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>
+# include <errno.h>
+
+/* If the vDSO is not available we fall back on the syscall.  */
+static int
+__gettimeofday_syscall (struct timeval *tv, struct timezone *tz)
+{
+  return INLINE_SYSCALL (gettimeofday, 2, tv, tz);
+}
+# define GETTIMEOFAY_FALLBACK (void*) (&__gettimeofday_syscall)
+# undef libc_ifunc_hidden_def
+# define libc_ifunc_hidden_def(name)  \
+  libc_ifunc_hidden_def1 (__GI_##name, __gettimeofday_syscall)
+
+#endif
+
+#include <sysdeps/unix/sysv/linux/x86/gettimeofday.c>
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 0000000..dc3b1ba
--- /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) 2014 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 (linux26, "LINUX_2.6", 61765110);
+
+  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>
diff --git a/sysdeps/unix/sysv/linux/i386/time.c b/sysdeps/unix/sysv/linux/i386/time.c
new file mode 100644
index 0000000..45b8a50
--- /dev/null
+++ b/sysdeps/unix/sysv/linux/i386/time.c
@@ -0,0 +1,37 @@ 
+/* time -- Get number of seconds since Epoch.  Linux/i386 version.
+   Copyright (C) 2014 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 <dl-vdso.h>
+# include <errno.h>
+
+/* If the vDSO is not available we fall back on the old vsyscall.  */
+static time_t
+__time_syscall (time_t *t)
+{
+  INTERNAL_SYSCALL_DECL (err);
+  return INTERNAL_SYSCALL (time, err, 1, t);
+}
+# define TIME_FALLBACK  (void*) &__time_syscall
+# undef libc_ifunc_hidden_def
+# define libc_ifunc_hidden_def(name)  \
+  libc_ifunc_hidden_def1 (__GI_##name, __time_syscall)
+#endif
+
+#include <sysdeps/unix/sysv/linux/x86/time.c>
diff --git a/sysdeps/unix/sysv/linux/x86/Makefile b/sysdeps/unix/sysv/linux/x86/Makefile
index 0281f87..d6be472 100644
--- a/sysdeps/unix/sysv/linux/x86/Makefile
+++ b/sysdeps/unix/sysv/linux/x86/Makefile
@@ -19,3 +19,7 @@  libpthread-sysdep_routines += init-arch
 libpthread-sysdep_routines += elision-lock elision-unlock elision-timed \
 			      elision-trylock
 endif
+
+ifeq ($(subdir),elf)
+sysdep_routines += dl-vdso
+endif
diff --git a/sysdeps/unix/sysv/linux/x86/clock_gettime.c b/sysdeps/unix/sysv/linux/x86/clock_gettime.c
new file mode 100644
index 0000000..2547a8c
--- /dev/null
+++ b/sysdeps/unix/sysv/linux/x86/clock_gettime.c
@@ -0,0 +1,38 @@ 
+/* Get the current value of a clock.  Linux/x86 version.
+   Copyright (C) 2014 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 <libc-vdso.h>
+
+#ifdef SHARED
+# define SYSCALL_GETTIME(id, tp) \
+  ({ long int (*f) (clockid_t, struct timespec *) = __vdso_clock_gettime; \
+  long int v_ret;							  \
+  PTR_DEMANGLE (f);							  \
+  v_ret = (*f) (id, tp);						  \
+  if (INTERNAL_SYSCALL_ERROR_P (v_ret, )) {				  \
+    __set_errno (INTERNAL_SYSCALL_ERRNO (v_ret, ));			  \
+    v_ret = -1;								  \
+  }									  \
+  v_ret; })
+# define INTERNAL_GETTIME(id, tp) \
+  ({ long int (*f) (clockid_t, struct timespec *) = __vdso_clock_gettime; \
+  PTR_DEMANGLE (f);							  \
+  (*f) (id, tp); })
+#endif
+
+#include <sysdeps/unix/sysv/linux/clock_gettime.c>
diff --git a/sysdeps/unix/sysv/linux/x86/gettimeofday.c b/sysdeps/unix/sysv/linux/x86/gettimeofday.c
new file mode 100644
index 0000000..54a3c1f
--- /dev/null
+++ b/sysdeps/unix/sysv/linux/x86/gettimeofday.c
@@ -0,0 +1,53 @@ 
+/* gettimeofday - get the time.  Linux/x86 version.
+   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 (linux26, "LINUX_2.6", 61765110);
+
+  /* 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)
diff --git a/sysdeps/unix/sysv/linux/x86/libc-vdso.h b/sysdeps/unix/sysv/linux/x86/libc-vdso.h
new file mode 100644
index 0000000..f291924
--- /dev/null
+++ b/sysdeps/unix/sysv/linux/x86/libc-vdso.h
@@ -0,0 +1,31 @@ 
+/* Resolve function pointers to VDSO functions.
+   Copyright (C) 2005-2014 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/>.  */
+
+#ifndef _LIBC_VDSO_H
+#define _LIBC_VDSO_H
+
+#include <time.h>
+#include <sys/time.h>
+
+#ifdef SHARED
+
+extern long int (*__vdso_clock_gettime) (clockid_t, struct timespec *);
+
+#endif
+
+#endif /* _LIBC_VDSO_H */
diff --git a/sysdeps/unix/sysv/linux/x86/time.c b/sysdeps/unix/sysv/linux/x86/time.c
new file mode 100644
index 0000000..f567d12
--- /dev/null
+++ b/sysdeps/unix/sysv/linux/x86/time.c
@@ -0,0 +1,49 @@ 
+/* time -- Get number of seconds since Epoch.  Linux/x86 version.
+   Copyright (C) 2014 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 <time.h>
+
+#ifdef SHARED
+
+#include <dl-vdso.h>
+
+void *time_ifunc (void) __asm__ ("time");
+
+void *
+time_ifunc (void)
+{
+  PREPARE_VERSION (linux26, "LINUX_2.6", 61765110);
+
+  return _dl_vdso_vsym ("__vdso_time", &linux26) ?: TIME_FALLBACK;
+}
+asm (".type time, %gnu_indirect_function");
+
+libc_ifunc_hidden_def(time)
+
+#else
+
+# include <sysdep.h>
+
+time_t
+time (time_t *t)
+{
+  INTERNAL_SYSCALL_DECL (err);
+  return INTERNAL_SYSCALL (time, err, 1, t);
+}
+
+#endif
diff --git a/sysdeps/unix/sysv/linux/x86/timespec_get.c b/sysdeps/unix/sysv/linux/x86/timespec_get.c
new file mode 100644
index 0000000..4b6d721
--- /dev/null
+++ b/sysdeps/unix/sysv/linux/x86/timespec_get.c
@@ -0,0 +1,29 @@ 
+/* timespec_get -- returns the calendar time based on a given time base.
+   Linux/x86 version.
+   Copyright (C) 2014 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 <libc-vdso.h>
+
+#ifdef SHARED
+# define INTERNAL_GETTIME(id, tp) \
+  ({ long int (*f) (clockid_t, struct timespec *) = __vdso_clock_gettime; \
+  PTR_DEMANGLE (f);							  \
+  (*f) (id, tp); })
+#endif
+
+#include <sysdeps/unix/sysv/linux/timespec_get.c>
diff --git a/sysdeps/unix/sysv/linux/x86_64/Makefile b/sysdeps/unix/sysv/linux/x86_64/Makefile
index d6a9d36..9b82155 100644
--- a/sysdeps/unix/sysv/linux/x86_64/Makefile
+++ b/sysdeps/unix/sysv/linux/x86_64/Makefile
@@ -13,7 +13,3 @@  endif
 ifeq ($(subdir),misc)
 gen-as-const-headers += sigaltstack-offsets.sym
 endif
-
-ifeq ($(subdir),elf)
-sysdep_routines += dl-vdso
-endif
diff --git a/sysdeps/unix/sysv/linux/x86_64/bits/libc-vdso.h b/sysdeps/unix/sysv/linux/x86_64/bits/libc-vdso.h
deleted file mode 100644
index f291924..0000000
--- a/sysdeps/unix/sysv/linux/x86_64/bits/libc-vdso.h
+++ /dev/null
@@ -1,31 +0,0 @@ 
-/* Resolve function pointers to VDSO functions.
-   Copyright (C) 2005-2014 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/>.  */
-
-#ifndef _LIBC_VDSO_H
-#define _LIBC_VDSO_H
-
-#include <time.h>
-#include <sys/time.h>
-
-#ifdef SHARED
-
-extern long int (*__vdso_clock_gettime) (clockid_t, struct timespec *);
-
-#endif
-
-#endif /* _LIBC_VDSO_H */
diff --git a/sysdeps/unix/sysv/linux/x86_64/clock_gettime.c b/sysdeps/unix/sysv/linux/x86_64/clock_gettime.c
deleted file mode 100644
index f712110..0000000
--- a/sysdeps/unix/sysv/linux/x86_64/clock_gettime.c
+++ /dev/null
@@ -1,20 +0,0 @@ 
-#include "bits/libc-vdso.h"
-
-#ifdef SHARED
-# define SYSCALL_GETTIME(id, tp) \
-  ({ long int (*f) (clockid_t, struct timespec *) = __vdso_clock_gettime; \
-  long int v_ret;							  \
-  PTR_DEMANGLE (f);							  \
-  v_ret = f (id, tp);							  \
-  if (INTERNAL_SYSCALL_ERROR_P (v_ret, )) {				  \
-    __set_errno (INTERNAL_SYSCALL_ERRNO (v_ret, ));			  \
-    v_ret = -1;								  \
-  }									  \
-  v_ret; })
-# define INTERNAL_GETTIME(id, tp) \
-  ({ long int (*f) (clockid_t, struct timespec *) = __vdso_clock_gettime; \
-  PTR_DEMANGLE (f);							  \
-  f (id, tp); })
-#endif
-
-#include "../clock_gettime.c"
diff --git a/sysdeps/unix/sysv/linux/x86_64/gettimeofday.c b/sysdeps/unix/sysv/linux/x86_64/gettimeofday.c
index 440ca7f..defefbc 100644
--- a/sysdeps/unix/sysv/linux/x86_64/gettimeofday.c
+++ b/sysdeps/unix/sysv/linux/x86_64/gettimeofday.c
@@ -18,42 +18,9 @@ 
 #include <sys/time.h>
 
 #ifdef SHARED
-
-# include <dl-vdso.h>
-
+/* If the vDSO is not available we fall back on the old vsyscall.  */
 # define VSYSCALL_ADDR_vgettimeofday	0xffffffffff600000ul
-
-void *gettimeofday_ifunc (void) __asm__ ("__gettimeofday");
-
-void *
-gettimeofday_ifunc (void)
-{
-  PREPARE_VERSION (linux26, "LINUX_2.6", 61765110);
-
-  /* If the vDSO is not available we fall back on the old vsyscall.  */
-  return (_dl_vdso_vsym ("__vdso_gettimeofday", &linux26)
-	  ?: (void *) VSYSCALL_ADDR_vgettimeofday);
-}
-asm (".type __gettimeofday, %gnu_indirect_function");
-
-/* This is doing "libc_hidden_def (__gettimeofday)" but the compiler won't
-   let us do it in C because it doesn't know we're defining __gettimeofday
-   here in this file.  */
-asm (".globl __GI___gettimeofday\n"
-     "__GI___gettimeofday = __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)
-
+# define GETTIMEOFAY_FALLBACK  (void*)VSYSCALL_ADDR_vgettimeofday
 #endif
-weak_alias (__gettimeofday, gettimeofday)
-libc_hidden_weak (gettimeofday)
+
+#include <sysdeps/unix/sysv/linux/x86/gettimeofday.c>
diff --git a/sysdeps/unix/sysv/linux/x86_64/init-first.c b/sysdeps/unix/sysv/linux/x86_64/init-first.c
index fb090df..827751a 100644
--- a/sysdeps/unix/sysv/linux/x86_64/init-first.c
+++ b/sysdeps/unix/sysv/linux/x86_64/init-first.c
@@ -20,20 +20,20 @@ 
 # include <time.h>
 # include <sysdep.h>
 # include <dl-vdso.h>
-# include <bits/libc-vdso.h>
+# include <libc-vdso.h>
 
 long int (*__vdso_clock_gettime) (clockid_t, struct timespec *)
   __attribute__ ((nocommon));
-strong_alias (__vdso_clock_gettime, __GI___vdso_clock_gettime attribute_hidden)
+libc_hidden_proto (__vdso_clock_gettime)
+libc_hidden_data_def (__vdso_clock_gettime)
 
 long int (*__vdso_getcpu) (unsigned *, unsigned *, void *) attribute_hidden;
 
-
 extern long int __syscall_clock_gettime (clockid_t, struct timespec *);
 
 
 static inline void
-_libc_vdso_platform_setup (void)
+__vdso_platform_setup (void)
 {
   PREPARE_VERSION (linux26, "LINUX_2.6", 61765110);
 
@@ -41,7 +41,7 @@  _libc_vdso_platform_setup (void)
   if (p == NULL)
     p = __syscall_clock_gettime;
   PTR_MANGLE (p);
-  __GI___vdso_clock_gettime = p;
+  __vdso_clock_gettime = p;
 
   p = _dl_vdso_vsym ("__vdso_getcpu", &linux26);
   /* If the vDSO is not available we fall back on the old vsyscall.  */
@@ -52,7 +52,7 @@  _libc_vdso_platform_setup (void)
   __vdso_getcpu = p;
 }
 
-# define VDSO_SETUP _libc_vdso_platform_setup
+# define VDSO_SETUP __vdso_platform_setup
 #endif
 
 #include <csu/init-first.c>
diff --git a/sysdeps/unix/sysv/linux/x86_64/time.c b/sysdeps/unix/sysv/linux/x86_64/time.c
index 79f1fab..ec1393b 100644
--- a/sysdeps/unix/sysv/linux/x86_64/time.c
+++ b/sysdeps/unix/sysv/linux/x86_64/time.c
@@ -16,45 +16,9 @@ 
    <http://www.gnu.org/licenses/>.  */
 
 #ifdef SHARED
-/* Redefine time so that the compiler won't complain about the type
-   mismatch with the IFUNC selector in strong_alias, below.  */
-#undef time
-#define time __redirect_time
-#include <time.h>
-
-#include <dl-vdso.h>
-
+/* If the vDSO is not available we fall back on the old vsyscall.  */
 #define VSYSCALL_ADDR_vtime	0xffffffffff600400
-
-/* Avoid DWARF definition DIE on ifunc symbol so that GDB can handle
-   ifunc symbol properly.  */
-extern __typeof (__redirect_time) __libc_time;
-void *time_ifunc (void) __asm__ ("__libc_time");
-
-void *
-time_ifunc (void)
-{
-  PREPARE_VERSION (linux26, "LINUX_2.6", 61765110);
-
-  /* If the vDSO is not available we fall back on the old vsyscall.  */
-  return _dl_vdso_vsym ("__vdso_time", &linux26) ?: (void *) VSYSCALL_ADDR_vtime;
-}
-__asm (".type __libc_time, %gnu_indirect_function");
-
-#undef time
-strong_alias (__libc_time, time)
-libc_hidden_ver (__libc_time, time)
-
-#else
-
-# include <time.h>
-# include <sysdep.h>
-
-time_t
-time (time_t *t)
-{
-  INTERNAL_SYSCALL_DECL (err);
-  return INTERNAL_SYSCALL (time, err, 1, t);
-}
-
+#define TIME_FALLBACK           (void*)VSYSCALL_ADDR_vtime
 #endif
+
+#include <sysdeps/unix/sysv/linux/x86/time.c>
diff --git a/sysdeps/unix/sysv/linux/x86_64/timespec_get.c b/sysdeps/unix/sysv/linux/x86_64/timespec_get.c
deleted file mode 100644
index cb26068..0000000
--- a/sysdeps/unix/sysv/linux/x86_64/timespec_get.c
+++ /dev/null
@@ -1,10 +0,0 @@ 
-#include "bits/libc-vdso.h"
-
-#ifdef SHARED
-# define INTERNAL_GETTIME(id, tp) \
-  ({ long int (*f) (clockid_t, struct timespec *) = __vdso_clock_gettime; \
-  PTR_DEMANGLE (f);							  \
-  f (id, tp); })
-#endif
-
-#include "../timespec_get.c"