x86: Remove vsyscall usage

Message ID 553963C1.2080600@linaro.org
State New
Headers show

Commit Message

Adhemerval Zanella April 23, 2015, 9:27 p.m.
This patch removes the vsyscall usage for x86_64 port.  As indicated
by kernel code comments [1], vsyscalls are a legacy ABI and its concept
is problematic:

- It interferes with ASLR.
- It's awkward to write code that lives in kernel addresses but is
  callable by userspace at fixed addresses.
- The whole concept is impossible for 32-bit compat userspace.
- UML cannot easily virtualize a vsyscall.

The VDSO is a better approach for such functionality.  Tested on i686,
x86_64, and x32.

[1] arch/x86/kernel/vsyscall_64.c

--

	* sysdeps/unix/sysv/linux/i386/gettimeofday.c
	(__gettimeofday_syscall): Remove.
	* sysdeps/unix/sysv/linux/i386/time.c (__time_syscall): Remove.
	* sysdeps/unix/sysv/linux/x86/gettimeofday.c (__gettimeofday_syscall):
	Add function.
	(gettimeofday_ifunc): Use __gettimeofday_syscall as fallback mechanism
	if vDSO is not present.
	* sysdeps/unix/sysv/linux/x86/time.c (__time_syscall): Add function.
	(time_ifunc): Use __time_syscall as fallback mechanism if vDSO is not
	present.
	* sysdeps/unix/sysv/linux/x86_64/gettimeofday.c: Remove file.
	* sysdeps/unix/sysv/linux/x86_64/time.c: Likewise.

---

Comments

Adhemerval Zanella May 11, 2015, 7:12 p.m. | #1
Ping.

On 23-04-2015 18:27, Adhemerval Zanella wrote:
> This patch removes the vsyscall usage for x86_64 port.  As indicated
> by kernel code comments [1], vsyscalls are a legacy ABI and its concept
> is problematic:
> 
> - It interferes with ASLR.
> - It's awkward to write code that lives in kernel addresses but is
>   callable by userspace at fixed addresses.
> - The whole concept is impossible for 32-bit compat userspace.
> - UML cannot easily virtualize a vsyscall.
> 
> The VDSO is a better approach for such functionality.  Tested on i686,
> x86_64, and x32.
> 
> [1] arch/x86/kernel/vsyscall_64.c
> 
> --
> 
> 	* sysdeps/unix/sysv/linux/i386/gettimeofday.c
> 	(__gettimeofday_syscall): Remove.
> 	* sysdeps/unix/sysv/linux/i386/time.c (__time_syscall): Remove.
> 	* sysdeps/unix/sysv/linux/x86/gettimeofday.c (__gettimeofday_syscall):
> 	Add function.
> 	(gettimeofday_ifunc): Use __gettimeofday_syscall as fallback mechanism
> 	if vDSO is not present.
> 	* sysdeps/unix/sysv/linux/x86/time.c (__time_syscall): Add function.
> 	(time_ifunc): Use __time_syscall as fallback mechanism if vDSO is not
> 	present.
> 	* sysdeps/unix/sysv/linux/x86_64/gettimeofday.c: Remove file.
> 	* sysdeps/unix/sysv/linux/x86_64/time.c: Likewise.
> 
> ---
> 
> diff --git a/sysdeps/unix/sysv/linux/i386/gettimeofday.c b/sysdeps/unix/sysv/linux/i386/gettimeofday.c
> index 3e00eb4..fdb0fab 100644
> --- a/sysdeps/unix/sysv/linux/i386/gettimeofday.c
> +++ b/sysdeps/unix/sysv/linux/i386/gettimeofday.c
> @@ -20,16 +20,6 @@
>  
>  #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)
> diff --git a/sysdeps/unix/sysv/linux/i386/time.c b/sysdeps/unix/sysv/linux/i386/time.c
> index e8a4e59..66b9a6c 100644
> --- a/sysdeps/unix/sysv/linux/i386/time.c
> +++ b/sysdeps/unix/sysv/linux/i386/time.c
> @@ -18,17 +18,6 @@
>  
>  #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)
> diff --git a/sysdeps/unix/sysv/linux/x86/gettimeofday.c b/sysdeps/unix/sysv/linux/x86/gettimeofday.c
> index c820fd7..c9cb6ea 100644
> --- a/sysdeps/unix/sysv/linux/x86/gettimeofday.c
> +++ b/sysdeps/unix/sysv/linux/x86/gettimeofday.c
> @@ -21,6 +21,14 @@
>  #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);
> +}
>  
>  void *gettimeofday_ifunc (void) __asm__ ("__gettimeofday");
>  
> @@ -31,7 +39,7 @@ gettimeofday_ifunc (void)
>  
>    /* If the vDSO is not available we fall back on the old vsyscall.  */
>    return (_dl_vdso_vsym ("__vdso_gettimeofday", &linux26)
> -	  ?: GETTIMEOFAY_FALLBACK);
> +	  ?: (void*) (&__gettimeofday_syscall));
>  }
>  asm (".type __gettimeofday, %gnu_indirect_function");
>  
> diff --git a/sysdeps/unix/sysv/linux/x86/time.c b/sysdeps/unix/sysv/linux/x86/time.c
> index 1ab9248..3459e17 100644
> --- a/sysdeps/unix/sysv/linux/x86/time.c
> +++ b/sysdeps/unix/sysv/linux/x86/time.c
> @@ -21,6 +21,15 @@
>  #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);
> +}
>  
>  void *time_ifunc (void) __asm__ ("time");
>  
> @@ -29,7 +38,8 @@ time_ifunc (void)
>  {
>    PREPARE_VERSION_KNOWN (linux26, LINUX_2_6);
>  
> -  return _dl_vdso_vsym ("__vdso_time", &linux26) ?: TIME_FALLBACK;
> +  return _dl_vdso_vsym ("__vdso_time", &linux26)
> +			?: (void*) &__time_syscall;
>  }
>  asm (".type time, %gnu_indirect_function");
>  
> diff --git a/sysdeps/unix/sysv/linux/x86_64/gettimeofday.c b/sysdeps/unix/sysv/linux/x86_64/gettimeofday.c
> deleted file mode 100644
> index daa14de..0000000
> --- a/sysdeps/unix/sysv/linux/x86_64/gettimeofday.c
> +++ /dev/null
> @@ -1,26 +0,0 @@
> -/* Copyright (C) 2002-2015 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
> -/* If the vDSO is not available we fall back on the old vsyscall.  */
> -# define VSYSCALL_ADDR_vgettimeofday	0xffffffffff600000ul
> -# define GETTIMEOFAY_FALLBACK  (void*)VSYSCALL_ADDR_vgettimeofday
> -#endif
> -
> -#include <sysdeps/unix/sysv/linux/x86/gettimeofday.c>
> diff --git a/sysdeps/unix/sysv/linux/x86_64/time.c b/sysdeps/unix/sysv/linux/x86_64/time.c
> deleted file mode 100644
> index 6ceb819..0000000
> --- a/sysdeps/unix/sysv/linux/x86_64/time.c
> +++ /dev/null
> @@ -1,24 +0,0 @@
> -/* Copyright (C) 2001-2015 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
> -/* If the vDSO is not available we fall back on the old vsyscall.  */
> -#define VSYSCALL_ADDR_vtime	0xffffffffff600400
> -#define TIME_FALLBACK           (void*)VSYSCALL_ADDR_vtime
> -#endif
> -
> -#include <sysdeps/unix/sysv/linux/x86/time.c>
>
Adhemerval Zanella June 5, 2015, 6:59 p.m. | #2
Ping.

On 11-05-2015 16:12, Adhemerval Zanella wrote:
> Ping.
> 
> On 23-04-2015 18:27, Adhemerval Zanella wrote:
>> This patch removes the vsyscall usage for x86_64 port.  As indicated
>> by kernel code comments [1], vsyscalls are a legacy ABI and its concept
>> is problematic:
>>
>> - It interferes with ASLR.
>> - It's awkward to write code that lives in kernel addresses but is
>>   callable by userspace at fixed addresses.
>> - The whole concept is impossible for 32-bit compat userspace.
>> - UML cannot easily virtualize a vsyscall.
>>
>> The VDSO is a better approach for such functionality.  Tested on i686,
>> x86_64, and x32.
>>
>> [1] arch/x86/kernel/vsyscall_64.c
>>
>> --
>>
>> 	* sysdeps/unix/sysv/linux/i386/gettimeofday.c
>> 	(__gettimeofday_syscall): Remove.
>> 	* sysdeps/unix/sysv/linux/i386/time.c (__time_syscall): Remove.
>> 	* sysdeps/unix/sysv/linux/x86/gettimeofday.c (__gettimeofday_syscall):
>> 	Add function.
>> 	(gettimeofday_ifunc): Use __gettimeofday_syscall as fallback mechanism
>> 	if vDSO is not present.
>> 	* sysdeps/unix/sysv/linux/x86/time.c (__time_syscall): Add function.
>> 	(time_ifunc): Use __time_syscall as fallback mechanism if vDSO is not
>> 	present.
>> 	* sysdeps/unix/sysv/linux/x86_64/gettimeofday.c: Remove file.
>> 	* sysdeps/unix/sysv/linux/x86_64/time.c: Likewise.
>>
>> ---
>>
>> diff --git a/sysdeps/unix/sysv/linux/i386/gettimeofday.c b/sysdeps/unix/sysv/linux/i386/gettimeofday.c
>> index 3e00eb4..fdb0fab 100644
>> --- a/sysdeps/unix/sysv/linux/i386/gettimeofday.c
>> +++ b/sysdeps/unix/sysv/linux/i386/gettimeofday.c
>> @@ -20,16 +20,6 @@
>>  
>>  #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)
>> diff --git a/sysdeps/unix/sysv/linux/i386/time.c b/sysdeps/unix/sysv/linux/i386/time.c
>> index e8a4e59..66b9a6c 100644
>> --- a/sysdeps/unix/sysv/linux/i386/time.c
>> +++ b/sysdeps/unix/sysv/linux/i386/time.c
>> @@ -18,17 +18,6 @@
>>  
>>  #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)
>> diff --git a/sysdeps/unix/sysv/linux/x86/gettimeofday.c b/sysdeps/unix/sysv/linux/x86/gettimeofday.c
>> index c820fd7..c9cb6ea 100644
>> --- a/sysdeps/unix/sysv/linux/x86/gettimeofday.c
>> +++ b/sysdeps/unix/sysv/linux/x86/gettimeofday.c
>> @@ -21,6 +21,14 @@
>>  #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);
>> +}
>>  
>>  void *gettimeofday_ifunc (void) __asm__ ("__gettimeofday");
>>  
>> @@ -31,7 +39,7 @@ gettimeofday_ifunc (void)
>>  
>>    /* If the vDSO is not available we fall back on the old vsyscall.  */
>>    return (_dl_vdso_vsym ("__vdso_gettimeofday", &linux26)
>> -	  ?: GETTIMEOFAY_FALLBACK);
>> +	  ?: (void*) (&__gettimeofday_syscall));
>>  }
>>  asm (".type __gettimeofday, %gnu_indirect_function");
>>  
>> diff --git a/sysdeps/unix/sysv/linux/x86/time.c b/sysdeps/unix/sysv/linux/x86/time.c
>> index 1ab9248..3459e17 100644
>> --- a/sysdeps/unix/sysv/linux/x86/time.c
>> +++ b/sysdeps/unix/sysv/linux/x86/time.c
>> @@ -21,6 +21,15 @@
>>  #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);
>> +}
>>  
>>  void *time_ifunc (void) __asm__ ("time");
>>  
>> @@ -29,7 +38,8 @@ time_ifunc (void)
>>  {
>>    PREPARE_VERSION_KNOWN (linux26, LINUX_2_6);
>>  
>> -  return _dl_vdso_vsym ("__vdso_time", &linux26) ?: TIME_FALLBACK;
>> +  return _dl_vdso_vsym ("__vdso_time", &linux26)
>> +			?: (void*) &__time_syscall;
>>  }
>>  asm (".type time, %gnu_indirect_function");
>>  
>> diff --git a/sysdeps/unix/sysv/linux/x86_64/gettimeofday.c b/sysdeps/unix/sysv/linux/x86_64/gettimeofday.c
>> deleted file mode 100644
>> index daa14de..0000000
>> --- a/sysdeps/unix/sysv/linux/x86_64/gettimeofday.c
>> +++ /dev/null
>> @@ -1,26 +0,0 @@
>> -/* Copyright (C) 2002-2015 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
>> -/* If the vDSO is not available we fall back on the old vsyscall.  */
>> -# define VSYSCALL_ADDR_vgettimeofday	0xffffffffff600000ul
>> -# define GETTIMEOFAY_FALLBACK  (void*)VSYSCALL_ADDR_vgettimeofday
>> -#endif
>> -
>> -#include <sysdeps/unix/sysv/linux/x86/gettimeofday.c>
>> diff --git a/sysdeps/unix/sysv/linux/x86_64/time.c b/sysdeps/unix/sysv/linux/x86_64/time.c
>> deleted file mode 100644
>> index 6ceb819..0000000
>> --- a/sysdeps/unix/sysv/linux/x86_64/time.c
>> +++ /dev/null
>> @@ -1,24 +0,0 @@
>> -/* Copyright (C) 2001-2015 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
>> -/* If the vDSO is not available we fall back on the old vsyscall.  */
>> -#define VSYSCALL_ADDR_vtime	0xffffffffff600400
>> -#define TIME_FALLBACK           (void*)VSYSCALL_ADDR_vtime
>> -#endif
>> -
>> -#include <sysdeps/unix/sysv/linux/x86/time.c>
>>
Adhemerval Zanella June 9, 2015, 8:31 p.m. | #3
I will commit it soon if noone opposes it.

On 05-06-2015 15:59, Adhemerval Zanella wrote:
> Ping.
> 
> On 11-05-2015 16:12, Adhemerval Zanella wrote:
>> Ping.
>>
>> On 23-04-2015 18:27, Adhemerval Zanella wrote:
>>> This patch removes the vsyscall usage for x86_64 port.  As indicated
>>> by kernel code comments [1], vsyscalls are a legacy ABI and its concept
>>> is problematic:
>>>
>>> - It interferes with ASLR.
>>> - It's awkward to write code that lives in kernel addresses but is
>>>   callable by userspace at fixed addresses.
>>> - The whole concept is impossible for 32-bit compat userspace.
>>> - UML cannot easily virtualize a vsyscall.
>>>
>>> The VDSO is a better approach for such functionality.  Tested on i686,
>>> x86_64, and x32.
>>>
>>> [1] arch/x86/kernel/vsyscall_64.c
>>>
>>> --
>>>
>>> 	* sysdeps/unix/sysv/linux/i386/gettimeofday.c
>>> 	(__gettimeofday_syscall): Remove.
>>> 	* sysdeps/unix/sysv/linux/i386/time.c (__time_syscall): Remove.
>>> 	* sysdeps/unix/sysv/linux/x86/gettimeofday.c (__gettimeofday_syscall):
>>> 	Add function.
>>> 	(gettimeofday_ifunc): Use __gettimeofday_syscall as fallback mechanism
>>> 	if vDSO is not present.
>>> 	* sysdeps/unix/sysv/linux/x86/time.c (__time_syscall): Add function.
>>> 	(time_ifunc): Use __time_syscall as fallback mechanism if vDSO is not
>>> 	present.
>>> 	* sysdeps/unix/sysv/linux/x86_64/gettimeofday.c: Remove file.
>>> 	* sysdeps/unix/sysv/linux/x86_64/time.c: Likewise.
>>>
>>> ---
>>>
>>> diff --git a/sysdeps/unix/sysv/linux/i386/gettimeofday.c b/sysdeps/unix/sysv/linux/i386/gettimeofday.c
>>> index 3e00eb4..fdb0fab 100644
>>> --- a/sysdeps/unix/sysv/linux/i386/gettimeofday.c
>>> +++ b/sysdeps/unix/sysv/linux/i386/gettimeofday.c
>>> @@ -20,16 +20,6 @@
>>>  
>>>  #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)
>>> diff --git a/sysdeps/unix/sysv/linux/i386/time.c b/sysdeps/unix/sysv/linux/i386/time.c
>>> index e8a4e59..66b9a6c 100644
>>> --- a/sysdeps/unix/sysv/linux/i386/time.c
>>> +++ b/sysdeps/unix/sysv/linux/i386/time.c
>>> @@ -18,17 +18,6 @@
>>>  
>>>  #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)
>>> diff --git a/sysdeps/unix/sysv/linux/x86/gettimeofday.c b/sysdeps/unix/sysv/linux/x86/gettimeofday.c
>>> index c820fd7..c9cb6ea 100644
>>> --- a/sysdeps/unix/sysv/linux/x86/gettimeofday.c
>>> +++ b/sysdeps/unix/sysv/linux/x86/gettimeofday.c
>>> @@ -21,6 +21,14 @@
>>>  #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);
>>> +}
>>>  
>>>  void *gettimeofday_ifunc (void) __asm__ ("__gettimeofday");
>>>  
>>> @@ -31,7 +39,7 @@ gettimeofday_ifunc (void)
>>>  
>>>    /* If the vDSO is not available we fall back on the old vsyscall.  */
>>>    return (_dl_vdso_vsym ("__vdso_gettimeofday", &linux26)
>>> -	  ?: GETTIMEOFAY_FALLBACK);
>>> +	  ?: (void*) (&__gettimeofday_syscall));
>>>  }
>>>  asm (".type __gettimeofday, %gnu_indirect_function");
>>>  
>>> diff --git a/sysdeps/unix/sysv/linux/x86/time.c b/sysdeps/unix/sysv/linux/x86/time.c
>>> index 1ab9248..3459e17 100644
>>> --- a/sysdeps/unix/sysv/linux/x86/time.c
>>> +++ b/sysdeps/unix/sysv/linux/x86/time.c
>>> @@ -21,6 +21,15 @@
>>>  #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);
>>> +}
>>>  
>>>  void *time_ifunc (void) __asm__ ("time");
>>>  
>>> @@ -29,7 +38,8 @@ time_ifunc (void)
>>>  {
>>>    PREPARE_VERSION_KNOWN (linux26, LINUX_2_6);
>>>  
>>> -  return _dl_vdso_vsym ("__vdso_time", &linux26) ?: TIME_FALLBACK;
>>> +  return _dl_vdso_vsym ("__vdso_time", &linux26)
>>> +			?: (void*) &__time_syscall;
>>>  }
>>>  asm (".type time, %gnu_indirect_function");
>>>  
>>> diff --git a/sysdeps/unix/sysv/linux/x86_64/gettimeofday.c b/sysdeps/unix/sysv/linux/x86_64/gettimeofday.c
>>> deleted file mode 100644
>>> index daa14de..0000000
>>> --- a/sysdeps/unix/sysv/linux/x86_64/gettimeofday.c
>>> +++ /dev/null
>>> @@ -1,26 +0,0 @@
>>> -/* Copyright (C) 2002-2015 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
>>> -/* If the vDSO is not available we fall back on the old vsyscall.  */
>>> -# define VSYSCALL_ADDR_vgettimeofday	0xffffffffff600000ul
>>> -# define GETTIMEOFAY_FALLBACK  (void*)VSYSCALL_ADDR_vgettimeofday
>>> -#endif
>>> -
>>> -#include <sysdeps/unix/sysv/linux/x86/gettimeofday.c>
>>> diff --git a/sysdeps/unix/sysv/linux/x86_64/time.c b/sysdeps/unix/sysv/linux/x86_64/time.c
>>> deleted file mode 100644
>>> index 6ceb819..0000000
>>> --- a/sysdeps/unix/sysv/linux/x86_64/time.c
>>> +++ /dev/null
>>> @@ -1,24 +0,0 @@
>>> -/* Copyright (C) 2001-2015 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
>>> -/* If the vDSO is not available we fall back on the old vsyscall.  */
>>> -#define VSYSCALL_ADDR_vtime	0xffffffffff600400
>>> -#define TIME_FALLBACK           (void*)VSYSCALL_ADDR_vtime
>>> -#endif
>>> -
>>> -#include <sysdeps/unix/sysv/linux/x86/time.c>
>>>

Patch

diff --git a/sysdeps/unix/sysv/linux/i386/gettimeofday.c b/sysdeps/unix/sysv/linux/i386/gettimeofday.c
index 3e00eb4..fdb0fab 100644
--- a/sysdeps/unix/sysv/linux/i386/gettimeofday.c
+++ b/sysdeps/unix/sysv/linux/i386/gettimeofday.c
@@ -20,16 +20,6 @@ 
 
 #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)
diff --git a/sysdeps/unix/sysv/linux/i386/time.c b/sysdeps/unix/sysv/linux/i386/time.c
index e8a4e59..66b9a6c 100644
--- a/sysdeps/unix/sysv/linux/i386/time.c
+++ b/sysdeps/unix/sysv/linux/i386/time.c
@@ -18,17 +18,6 @@ 
 
 #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)
diff --git a/sysdeps/unix/sysv/linux/x86/gettimeofday.c b/sysdeps/unix/sysv/linux/x86/gettimeofday.c
index c820fd7..c9cb6ea 100644
--- a/sysdeps/unix/sysv/linux/x86/gettimeofday.c
+++ b/sysdeps/unix/sysv/linux/x86/gettimeofday.c
@@ -21,6 +21,14 @@ 
 #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);
+}
 
 void *gettimeofday_ifunc (void) __asm__ ("__gettimeofday");
 
@@ -31,7 +39,7 @@  gettimeofday_ifunc (void)
 
   /* If the vDSO is not available we fall back on the old vsyscall.  */
   return (_dl_vdso_vsym ("__vdso_gettimeofday", &linux26)
-	  ?: GETTIMEOFAY_FALLBACK);
+	  ?: (void*) (&__gettimeofday_syscall));
 }
 asm (".type __gettimeofday, %gnu_indirect_function");
 
diff --git a/sysdeps/unix/sysv/linux/x86/time.c b/sysdeps/unix/sysv/linux/x86/time.c
index 1ab9248..3459e17 100644
--- a/sysdeps/unix/sysv/linux/x86/time.c
+++ b/sysdeps/unix/sysv/linux/x86/time.c
@@ -21,6 +21,15 @@ 
 #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);
+}
 
 void *time_ifunc (void) __asm__ ("time");
 
@@ -29,7 +38,8 @@  time_ifunc (void)
 {
   PREPARE_VERSION_KNOWN (linux26, LINUX_2_6);
 
-  return _dl_vdso_vsym ("__vdso_time", &linux26) ?: TIME_FALLBACK;
+  return _dl_vdso_vsym ("__vdso_time", &linux26)
+			?: (void*) &__time_syscall;
 }
 asm (".type time, %gnu_indirect_function");
 
diff --git a/sysdeps/unix/sysv/linux/x86_64/gettimeofday.c b/sysdeps/unix/sysv/linux/x86_64/gettimeofday.c
deleted file mode 100644
index daa14de..0000000
--- a/sysdeps/unix/sysv/linux/x86_64/gettimeofday.c
+++ /dev/null
@@ -1,26 +0,0 @@ 
-/* Copyright (C) 2002-2015 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
-/* If the vDSO is not available we fall back on the old vsyscall.  */
-# define VSYSCALL_ADDR_vgettimeofday	0xffffffffff600000ul
-# define GETTIMEOFAY_FALLBACK  (void*)VSYSCALL_ADDR_vgettimeofday
-#endif
-
-#include <sysdeps/unix/sysv/linux/x86/gettimeofday.c>
diff --git a/sysdeps/unix/sysv/linux/x86_64/time.c b/sysdeps/unix/sysv/linux/x86_64/time.c
deleted file mode 100644
index 6ceb819..0000000
--- a/sysdeps/unix/sysv/linux/x86_64/time.c
+++ /dev/null
@@ -1,24 +0,0 @@ 
-/* Copyright (C) 2001-2015 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
-/* If the vDSO is not available we fall back on the old vsyscall.  */
-#define VSYSCALL_ADDR_vtime	0xffffffffff600400
-#define TIME_FALLBACK           (void*)VSYSCALL_ADDR_vtime
-#endif
-
-#include <sysdeps/unix/sysv/linux/x86/time.c>