Patchwork [v3,2/2] sysdeps/clock_gettime: Use clock_gettime64 if avaliable

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Submitter Alistair Francis
Date Nov. 23, 2019, 10:27 p.m.
Message ID <20191123222708.17021-2-alistair.francis@wdc.com>
Download mbox | patch
Permalink /patch/36159/
State New
Headers show

Comments

Alistair Francis - Nov. 23, 2019, 10:27 p.m.
With the clock_gettime64 call we prefer to use vDSO. There is no call
to clock_gettime64 on glibc with older headers and kernel 5.1+ if it
doesn't support vDSO.
---
This was patch was runtime tested with RV32 and RV64
It was build tested using the ./scripts/build-many-glibcs.py script.

I also ran:
$ make ; make install ; make check
tests on native ARM (32-bit) with the following three confiugrations:
 - 4.19 Kernel and 4.19 Headers
 - 5.2 Kernel and 4.19 Headers
 - 5.2 Kernel and 5.2 Headers
and didn't see any regressions

v3:
 - Assume HAVE_CLOCK_GETTIME64_VSYSCALL means we have __NR_clock_gettime64
 - Change code style to be more glibc-ish
v2:
 - Add commit message
 - Change ret_64 to int

 include/time.h                          |  3 ++
 sysdeps/unix/sysv/linux/clock_gettime.c | 44 ++++++++++++++++++++++++-
 2 files changed, 46 insertions(+), 1 deletion(-)
Alistair Francis - Dec. 3, 2019, 6:56 p.m.
On Sat, Nov 23, 2019 at 2:32 PM Alistair Francis
<alistair.francis@wdc.com> wrote:
>
> With the clock_gettime64 call we prefer to use vDSO. There is no call
> to clock_gettime64 on glibc with older headers and kernel 5.1+ if it
> doesn't support vDSO.

Ping!

Alistair

> ---
> This was patch was runtime tested with RV32 and RV64
> It was build tested using the ./scripts/build-many-glibcs.py script.
>
> I also ran:
> $ make ; make install ; make check
> tests on native ARM (32-bit) with the following three confiugrations:
>  - 4.19 Kernel and 4.19 Headers
>  - 5.2 Kernel and 4.19 Headers
>  - 5.2 Kernel and 5.2 Headers
> and didn't see any regressions
>
> v3:
>  - Assume HAVE_CLOCK_GETTIME64_VSYSCALL means we have __NR_clock_gettime64
>  - Change code style to be more glibc-ish
> v2:
>  - Add commit message
>  - Change ret_64 to int
>
>  include/time.h                          |  3 ++
>  sysdeps/unix/sysv/linux/clock_gettime.c | 44 ++++++++++++++++++++++++-
>  2 files changed, 46 insertions(+), 1 deletion(-)
>
> diff --git a/include/time.h b/include/time.h
> index d7800eb30f..c19c73ae09 100644
> --- a/include/time.h
> +++ b/include/time.h
> @@ -211,11 +211,14 @@ extern double __difftime (time_t time1, time_t time0);
>
>  #if __TIMESIZE == 64
>  # define __clock_nanosleep_time64 __clock_nanosleep
> +# define __clock_gettime64 __clock_gettime
>  #else
>  extern int __clock_nanosleep_time64 (clockid_t clock_id,
>                                       int flags, const struct __timespec64 *req,
>                                       struct __timespec64 *rem);
>  libc_hidden_proto (__clock_nanosleep_time64)
> +extern int __clock_gettime64 (clockid_t clock_id, struct __timespec64 *tp);
> +libc_hidden_proto (__clock_gettime64)
>  #endif
>
>  /* Use in the clock_* functions.  Size of the field representing the
> diff --git a/sysdeps/unix/sysv/linux/clock_gettime.c b/sysdeps/unix/sysv/linux/clock_gettime.c
> index ca40983f6c..875c4fe905 100644
> --- a/sysdeps/unix/sysv/linux/clock_gettime.c
> +++ b/sysdeps/unix/sysv/linux/clock_gettime.c
> @@ -17,6 +17,7 @@
>     <https://www.gnu.org/licenses/>.  */
>
>  #include <sysdep.h>
> +#include <kernel-features.h>
>  #include <errno.h>
>  #include <time.h>
>  #include "kernel-posix-cpu-timers.h"
> @@ -30,10 +31,51 @@
>
>  /* Get current value of CLOCK and store it in TP.  */
>  int
> +__clock_gettime64 (clockid_t clock_id, struct __timespec64 *tp)
> +{
> +#ifdef __ASSUME_TIME64_SYSCALLS
> +# ifndef __NR_clock_gettime64
> +#  define __NR_clock_gettime64   __NR_clock_gettime
> +#  define __vdso_clock_gettime64 __vdso_clock_gettime
> +# endif
> +   return INLINE_VSYSCALL (clock_gettime64, 2, clock_id, tp);
> +#else
> +# if defined HAVE_CLOCK_GETTIME64_VSYSCALL
> +  int ret64 = INLINE_VSYSCALL (clock_gettime64, 2, clock_id, tp);
> +  if (ret64 == 0 || errno != ENOSYS)
> +    return ret64;
> +# endif
> +  struct timespec tp32;
> +  int ret = INLINE_VSYSCALL (clock_gettime, 2, clock_id, &tp32);
> +  if (ret == 0)
> +    *tp = valid_timespec_to_timespec64 (tp32);
> +  return ret;
> +#endif
> +}
> +
> +#if __TIMESIZE != 64
> +int
>  __clock_gettime (clockid_t clock_id, struct timespec *tp)
>  {
> -  return INLINE_VSYSCALL (clock_gettime, 2, clock_id, tp);
> +  int ret;
> +  struct __timespec64 tp64;
> +
> +  ret = __clock_gettime64 (clock_id, &tp64);
> +
> +  if (ret == 0)
> +    {
> +      if (! in_time_t_range (tp64.tv_sec))
> +        {
> +          __set_errno (EOVERFLOW);
> +          return -1;
> +        }
> +
> +      *tp = valid_timespec64_to_timespec (tp64);
> +    }
> +
> +  return ret;
>  }
> +#endif
>  libc_hidden_def (__clock_gettime)
>
>  versioned_symbol (libc, __clock_gettime, clock_gettime, GLIBC_2_17);
> --
> 2.24.0
>
Adhemerval Zanella Netto - Dec. 3, 2019, 7:29 p.m.
On 23/11/2019 19:27, Alistair Francis wrote:
> With the clock_gettime64 call we prefer to use vDSO. There is no call
> to clock_gettime64 on glibc with older headers and kernel 5.1+ if it
> doesn't support vDSO.

Ok with the fix below regarding HAVE_CLOCK_GETTIME64_VSYSCALL.

> ---
> This was patch was runtime tested with RV32 and RV64
> It was build tested using the ./scripts/build-many-glibcs.py script.
> 
> I also ran:
> $ make ; make install ; make check
> tests on native ARM (32-bit) with the following three confiugrations:
>  - 4.19 Kernel and 4.19 Headers
>  - 5.2 Kernel and 4.19 Headers
>  - 5.2 Kernel and 5.2 Headers
> and didn't see any regressions
> 
> v3:
>  - Assume HAVE_CLOCK_GETTIME64_VSYSCALL means we have __NR_clock_gettime64
>  - Change code style to be more glibc-ish
> v2:
>  - Add commit message
>  - Change ret_64 to int
> 
>  include/time.h                          |  3 ++
>  sysdeps/unix/sysv/linux/clock_gettime.c | 44 ++++++++++++++++++++++++-
>  2 files changed, 46 insertions(+), 1 deletion(-)
> 
> diff --git a/include/time.h b/include/time.h
> index d7800eb30f..c19c73ae09 100644
> --- a/include/time.h
> +++ b/include/time.h
> @@ -211,11 +211,14 @@ extern double __difftime (time_t time1, time_t time0);
>  
>  #if __TIMESIZE == 64
>  # define __clock_nanosleep_time64 __clock_nanosleep
> +# define __clock_gettime64 __clock_gettime
>  #else
>  extern int __clock_nanosleep_time64 (clockid_t clock_id,
>                                       int flags, const struct __timespec64 *req,
>                                       struct __timespec64 *rem);
>  libc_hidden_proto (__clock_nanosleep_time64)
> +extern int __clock_gettime64 (clockid_t clock_id, struct __timespec64 *tp);
> +libc_hidden_proto (__clock_gettime64)
>  #endif
>  
>  /* Use in the clock_* functions.  Size of the field representing the
> diff --git a/sysdeps/unix/sysv/linux/clock_gettime.c b/sysdeps/unix/sysv/linux/clock_gettime.c
> index ca40983f6c..875c4fe905 100644
> --- a/sysdeps/unix/sysv/linux/clock_gettime.c
> +++ b/sysdeps/unix/sysv/linux/clock_gettime.c
> @@ -17,6 +17,7 @@
>     <https://www.gnu.org/licenses/>.  */
>  
>  #include <sysdep.h>
> +#include <kernel-features.h>
>  #include <errno.h>
>  #include <time.h>
>  #include "kernel-posix-cpu-timers.h"
> @@ -30,10 +31,51 @@
>  
>  /* Get current value of CLOCK and store it in TP.  */
>  int
> +__clock_gettime64 (clockid_t clock_id, struct __timespec64 *tp)
> +{
> +#ifdef __ASSUME_TIME64_SYSCALLS
> +# ifndef __NR_clock_gettime64
> +#  define __NR_clock_gettime64   __NR_clock_gettime
> +#  define __vdso_clock_gettime64 __vdso_clock_gettime
> +# endif
> +   return INLINE_VSYSCALL (clock_gettime64, 2, clock_id, tp);

Ok, in this case either __vdso_clock_gettime/__NR_clock_gettime or
__vdso_clock_gettime64/__NR_clock_gettime64 will be called.

> +#else
> +# if defined HAVE_CLOCK_GETTIME64_VSYSCALL
> +  int ret64 = INLINE_VSYSCALL (clock_gettime64, 2, clock_id, tp);
> +  if (ret64 == 0 || errno != ENOSYS)
> +    return ret64;
> +# endif
This should be:

#if defined __NR_clock_gettime64
  int ret64 = INLINE_VSYSCALL (clock_gettime64, ...)
  [...]

And before sysdep-vdso.h it should be.

#if defined HAVE_CLOCK_GETTIME_VSYSCALL || defined HAVE_CLOCK_GETTIME64_VSYSCALL
# define HAVE_SYSCALL
#endif

If !HAVE_SYSCALL the INLINE_VSYSCALL is defined as INLINE_SYCALL.
It means that if an architecture does provide __NR_clock_gettime64
but not provide HAVE_CLOCK_GETTIME64_VSYSCALL, it will still use
the syscall. This code only uses the syscall if the vDSO is still
present.

I hope I can get my vDSO refactor, which would simplify a bit this
code.

> +  struct timespec tp32;
> +  int ret = INLINE_VSYSCALL (clock_gettime, 2, clock_id, &tp32);
> +  if (ret == 0)
> +    *tp = valid_timespec_to_timespec64 (tp32);
> +  return ret;
> +#endif
> +}

Ok, old fallback to time32 vdso/syscall.

> +
> +#if __TIMESIZE != 64
> +int
>  __clock_gettime (clockid_t clock_id, struct timespec *tp)
>  {
> -  return INLINE_VSYSCALL (clock_gettime, 2, clock_id, tp);
> +  int ret;
> +  struct __timespec64 tp64;
> +
> +  ret = __clock_gettime64 (clock_id, &tp64);
> +
> +  if (ret == 0)
> +    {
> +      if (! in_time_t_range (tp64.tv_sec))
> +        {
> +          __set_errno (EOVERFLOW);
> +          return -1;
> +        }
> +
> +      *tp = valid_timespec64_to_timespec (tp64);
> +    }
> +
> +  return ret;
>  }
> +#endif
>  libc_hidden_def (__clock_gettime)
>  
>  versioned_symbol (libc, __clock_gettime, clock_gettime, GLIBC_2_17);
> 

Ok.
Adhemerval Zanella Netto - Dec. 4, 2019, 5:24 p.m.
On 03/12/2019 16:29, Adhemerval Zanella wrote:
> 
> 
> On 23/11/2019 19:27, Alistair Francis wrote:
>> With the clock_gettime64 call we prefer to use vDSO. There is no call
>> to clock_gettime64 on glibc with older headers and kernel 5.1+ if it
>> doesn't support vDSO.
> 
> Ok with the fix below regarding HAVE_CLOCK_GETTIME64_VSYSCALL.

As [1] I think we can handle both the cases:

  8.  Define both __NR_clock_gettime64, provide a 64-bit vDSO, define
      __NR_clock_gettime, and provide a 32-bit vDSO.
      - i.e: some 32-bits ports built against kernel header equal or newer
        then v5.1 (i386, arm, and mips).

  9.  Define both __NR_clock_gettime64, provide a 64-bit vDSO, and
      define __NR_clock_gettime (unlikely, but possible)..

With my vDSO refactor to use relro data structures.

This patch is ok.

Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>

[1] https://sourceware.org/ml/libc-alpha/2019-12/msg00142.html

> 
>> ---
>> This was patch was runtime tested with RV32 and RV64
>> It was build tested using the ./scripts/build-many-glibcs.py script.
>>
>> I also ran:
>> $ make ; make install ; make check
>> tests on native ARM (32-bit) with the following three confiugrations:
>>  - 4.19 Kernel and 4.19 Headers
>>  - 5.2 Kernel and 4.19 Headers
>>  - 5.2 Kernel and 5.2 Headers
>> and didn't see any regressions
>>
>> v3:
>>  - Assume HAVE_CLOCK_GETTIME64_VSYSCALL means we have __NR_clock_gettime64
>>  - Change code style to be more glibc-ish
>> v2:
>>  - Add commit message
>>  - Change ret_64 to int
>>
>>  include/time.h                          |  3 ++
>>  sysdeps/unix/sysv/linux/clock_gettime.c | 44 ++++++++++++++++++++++++-
>>  2 files changed, 46 insertions(+), 1 deletion(-)
>>
>> diff --git a/include/time.h b/include/time.h
>> index d7800eb30f..c19c73ae09 100644
>> --- a/include/time.h
>> +++ b/include/time.h
>> @@ -211,11 +211,14 @@ extern double __difftime (time_t time1, time_t time0);
>>  
>>  #if __TIMESIZE == 64
>>  # define __clock_nanosleep_time64 __clock_nanosleep
>> +# define __clock_gettime64 __clock_gettime
>>  #else
>>  extern int __clock_nanosleep_time64 (clockid_t clock_id,
>>                                       int flags, const struct __timespec64 *req,
>>                                       struct __timespec64 *rem);
>>  libc_hidden_proto (__clock_nanosleep_time64)
>> +extern int __clock_gettime64 (clockid_t clock_id, struct __timespec64 *tp);
>> +libc_hidden_proto (__clock_gettime64)
>>  #endif
>>  
>>  /* Use in the clock_* functions.  Size of the field representing the
>> diff --git a/sysdeps/unix/sysv/linux/clock_gettime.c b/sysdeps/unix/sysv/linux/clock_gettime.c
>> index ca40983f6c..875c4fe905 100644
>> --- a/sysdeps/unix/sysv/linux/clock_gettime.c
>> +++ b/sysdeps/unix/sysv/linux/clock_gettime.c
>> @@ -17,6 +17,7 @@
>>     <https://www.gnu.org/licenses/>.  */
>>  
>>  #include <sysdep.h>
>> +#include <kernel-features.h>
>>  #include <errno.h>
>>  #include <time.h>
>>  #include "kernel-posix-cpu-timers.h"
>> @@ -30,10 +31,51 @@
>>  
>>  /* Get current value of CLOCK and store it in TP.  */
>>  int
>> +__clock_gettime64 (clockid_t clock_id, struct __timespec64 *tp)
>> +{
>> +#ifdef __ASSUME_TIME64_SYSCALLS
>> +# ifndef __NR_clock_gettime64
>> +#  define __NR_clock_gettime64   __NR_clock_gettime
>> +#  define __vdso_clock_gettime64 __vdso_clock_gettime
>> +# endif
>> +   return INLINE_VSYSCALL (clock_gettime64, 2, clock_id, tp);
> 
> Ok, in this case either __vdso_clock_gettime/__NR_clock_gettime or
> __vdso_clock_gettime64/__NR_clock_gettime64 will be called.
> 
>> +#else
>> +# if defined HAVE_CLOCK_GETTIME64_VSYSCALL
>> +  int ret64 = INLINE_VSYSCALL (clock_gettime64, 2, clock_id, tp);
>> +  if (ret64 == 0 || errno != ENOSYS)
>> +    return ret64;
>> +# endif
> This should be:
> 
> #if defined __NR_clock_gettime64
>   int ret64 = INLINE_VSYSCALL (clock_gettime64, ...)
>   [...]
> 
> And before sysdep-vdso.h it should be.
> 
> #if defined HAVE_CLOCK_GETTIME_VSYSCALL || defined HAVE_CLOCK_GETTIME64_VSYSCALL
> # define HAVE_SYSCALL
> #endif
> 
> If !HAVE_SYSCALL the INLINE_VSYSCALL is defined as INLINE_SYCALL.
> It means that if an architecture does provide __NR_clock_gettime64
> but not provide HAVE_CLOCK_GETTIME64_VSYSCALL, it will still use
> the syscall. This code only uses the syscall if the vDSO is still
> present.
> 
> I hope I can get my vDSO refactor, which would simplify a bit this
> code.
> 
>> +  struct timespec tp32;
>> +  int ret = INLINE_VSYSCALL (clock_gettime, 2, clock_id, &tp32);
>> +  if (ret == 0)
>> +    *tp = valid_timespec_to_timespec64 (tp32);
>> +  return ret;
>> +#endif
>> +}
> 
> Ok, old fallback to time32 vdso/syscall.
> 
>> +
>> +#if __TIMESIZE != 64
>> +int
>>  __clock_gettime (clockid_t clock_id, struct timespec *tp)
>>  {
>> -  return INLINE_VSYSCALL (clock_gettime, 2, clock_id, tp);
>> +  int ret;
>> +  struct __timespec64 tp64;
>> +
>> +  ret = __clock_gettime64 (clock_id, &tp64);
>> +
>> +  if (ret == 0)
>> +    {
>> +      if (! in_time_t_range (tp64.tv_sec))
>> +        {
>> +          __set_errno (EOVERFLOW);
>> +          return -1;
>> +        }
>> +
>> +      *tp = valid_timespec64_to_timespec (tp64);
>> +    }
>> +
>> +  return ret;
>>  }
>> +#endif
>>  libc_hidden_def (__clock_gettime)
>>  
>>  versioned_symbol (libc, __clock_gettime, clock_gettime, GLIBC_2_17);
>>
> 
> Ok.
>
Alistair Francis - Dec. 4, 2019, 5:42 p.m.
On Wed, Dec 4, 2019 at 9:24 AM Adhemerval Zanella
<adhemerval.zanella@linaro.org> wrote:
>
>
>
> On 03/12/2019 16:29, Adhemerval Zanella wrote:
> >
> >
> > On 23/11/2019 19:27, Alistair Francis wrote:
> >> With the clock_gettime64 call we prefer to use vDSO. There is no call
> >> to clock_gettime64 on glibc with older headers and kernel 5.1+ if it
> >> doesn't support vDSO.
> >
> > Ok with the fix below regarding HAVE_CLOCK_GETTIME64_VSYSCALL.
>
> As [1] I think we can handle both the cases:
>
>   8.  Define both __NR_clock_gettime64, provide a 64-bit vDSO, define
>       __NR_clock_gettime, and provide a 32-bit vDSO.
>       - i.e: some 32-bits ports built against kernel header equal or newer
>         then v5.1 (i386, arm, and mips).
>
>   9.  Define both __NR_clock_gettime64, provide a 64-bit vDSO, and
>       define __NR_clock_gettime (unlikely, but possible)..
>
> With my vDSO refactor to use relro data structures.
>
> This patch is ok.
>
> Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>

Thanks :)

I'll apply these two patches later today unless there are any other comments.

Alistair

>
> [1] https://sourceware.org/ml/libc-alpha/2019-12/msg00142.html
>
> >
> >> ---
> >> This was patch was runtime tested with RV32 and RV64
> >> It was build tested using the ./scripts/build-many-glibcs.py script.
> >>
> >> I also ran:
> >> $ make ; make install ; make check
> >> tests on native ARM (32-bit) with the following three confiugrations:
> >>  - 4.19 Kernel and 4.19 Headers
> >>  - 5.2 Kernel and 4.19 Headers
> >>  - 5.2 Kernel and 5.2 Headers
> >> and didn't see any regressions
> >>
> >> v3:
> >>  - Assume HAVE_CLOCK_GETTIME64_VSYSCALL means we have __NR_clock_gettime64
> >>  - Change code style to be more glibc-ish
> >> v2:
> >>  - Add commit message
> >>  - Change ret_64 to int
> >>
> >>  include/time.h                          |  3 ++
> >>  sysdeps/unix/sysv/linux/clock_gettime.c | 44 ++++++++++++++++++++++++-
> >>  2 files changed, 46 insertions(+), 1 deletion(-)
> >>
> >> diff --git a/include/time.h b/include/time.h
> >> index d7800eb30f..c19c73ae09 100644
> >> --- a/include/time.h
> >> +++ b/include/time.h
> >> @@ -211,11 +211,14 @@ extern double __difftime (time_t time1, time_t time0);
> >>
> >>  #if __TIMESIZE == 64
> >>  # define __clock_nanosleep_time64 __clock_nanosleep
> >> +# define __clock_gettime64 __clock_gettime
> >>  #else
> >>  extern int __clock_nanosleep_time64 (clockid_t clock_id,
> >>                                       int flags, const struct __timespec64 *req,
> >>                                       struct __timespec64 *rem);
> >>  libc_hidden_proto (__clock_nanosleep_time64)
> >> +extern int __clock_gettime64 (clockid_t clock_id, struct __timespec64 *tp);
> >> +libc_hidden_proto (__clock_gettime64)
> >>  #endif
> >>
> >>  /* Use in the clock_* functions.  Size of the field representing the
> >> diff --git a/sysdeps/unix/sysv/linux/clock_gettime.c b/sysdeps/unix/sysv/linux/clock_gettime.c
> >> index ca40983f6c..875c4fe905 100644
> >> --- a/sysdeps/unix/sysv/linux/clock_gettime.c
> >> +++ b/sysdeps/unix/sysv/linux/clock_gettime.c
> >> @@ -17,6 +17,7 @@
> >>     <https://www.gnu.org/licenses/>.  */
> >>
> >>  #include <sysdep.h>
> >> +#include <kernel-features.h>
> >>  #include <errno.h>
> >>  #include <time.h>
> >>  #include "kernel-posix-cpu-timers.h"
> >> @@ -30,10 +31,51 @@
> >>
> >>  /* Get current value of CLOCK and store it in TP.  */
> >>  int
> >> +__clock_gettime64 (clockid_t clock_id, struct __timespec64 *tp)
> >> +{
> >> +#ifdef __ASSUME_TIME64_SYSCALLS
> >> +# ifndef __NR_clock_gettime64
> >> +#  define __NR_clock_gettime64   __NR_clock_gettime
> >> +#  define __vdso_clock_gettime64 __vdso_clock_gettime
> >> +# endif
> >> +   return INLINE_VSYSCALL (clock_gettime64, 2, clock_id, tp);
> >
> > Ok, in this case either __vdso_clock_gettime/__NR_clock_gettime or
> > __vdso_clock_gettime64/__NR_clock_gettime64 will be called.
> >
> >> +#else
> >> +# if defined HAVE_CLOCK_GETTIME64_VSYSCALL
> >> +  int ret64 = INLINE_VSYSCALL (clock_gettime64, 2, clock_id, tp);
> >> +  if (ret64 == 0 || errno != ENOSYS)
> >> +    return ret64;
> >> +# endif
> > This should be:
> >
> > #if defined __NR_clock_gettime64
> >   int ret64 = INLINE_VSYSCALL (clock_gettime64, ...)
> >   [...]
> >
> > And before sysdep-vdso.h it should be.
> >
> > #if defined HAVE_CLOCK_GETTIME_VSYSCALL || defined HAVE_CLOCK_GETTIME64_VSYSCALL
> > # define HAVE_SYSCALL
> > #endif
> >
> > If !HAVE_SYSCALL the INLINE_VSYSCALL is defined as INLINE_SYCALL.
> > It means that if an architecture does provide __NR_clock_gettime64
> > but not provide HAVE_CLOCK_GETTIME64_VSYSCALL, it will still use
> > the syscall. This code only uses the syscall if the vDSO is still
> > present.
> >
> > I hope I can get my vDSO refactor, which would simplify a bit this
> > code.
> >
> >> +  struct timespec tp32;
> >> +  int ret = INLINE_VSYSCALL (clock_gettime, 2, clock_id, &tp32);
> >> +  if (ret == 0)
> >> +    *tp = valid_timespec_to_timespec64 (tp32);
> >> +  return ret;
> >> +#endif
> >> +}
> >
> > Ok, old fallback to time32 vdso/syscall.
> >
> >> +
> >> +#if __TIMESIZE != 64
> >> +int
> >>  __clock_gettime (clockid_t clock_id, struct timespec *tp)
> >>  {
> >> -  return INLINE_VSYSCALL (clock_gettime, 2, clock_id, tp);
> >> +  int ret;
> >> +  struct __timespec64 tp64;
> >> +
> >> +  ret = __clock_gettime64 (clock_id, &tp64);
> >> +
> >> +  if (ret == 0)
> >> +    {
> >> +      if (! in_time_t_range (tp64.tv_sec))
> >> +        {
> >> +          __set_errno (EOVERFLOW);
> >> +          return -1;
> >> +        }
> >> +
> >> +      *tp = valid_timespec64_to_timespec (tp64);
> >> +    }
> >> +
> >> +  return ret;
> >>  }
> >> +#endif
> >>  libc_hidden_def (__clock_gettime)
> >>
> >>  versioned_symbol (libc, __clock_gettime, clock_gettime, GLIBC_2_17);
> >>
> >
> > Ok.
> >

Patch

diff --git a/include/time.h b/include/time.h
index d7800eb30f..c19c73ae09 100644
--- a/include/time.h
+++ b/include/time.h
@@ -211,11 +211,14 @@  extern double __difftime (time_t time1, time_t time0);
 
 #if __TIMESIZE == 64
 # define __clock_nanosleep_time64 __clock_nanosleep
+# define __clock_gettime64 __clock_gettime
 #else
 extern int __clock_nanosleep_time64 (clockid_t clock_id,
                                      int flags, const struct __timespec64 *req,
                                      struct __timespec64 *rem);
 libc_hidden_proto (__clock_nanosleep_time64)
+extern int __clock_gettime64 (clockid_t clock_id, struct __timespec64 *tp);
+libc_hidden_proto (__clock_gettime64)
 #endif
 
 /* Use in the clock_* functions.  Size of the field representing the
diff --git a/sysdeps/unix/sysv/linux/clock_gettime.c b/sysdeps/unix/sysv/linux/clock_gettime.c
index ca40983f6c..875c4fe905 100644
--- a/sysdeps/unix/sysv/linux/clock_gettime.c
+++ b/sysdeps/unix/sysv/linux/clock_gettime.c
@@ -17,6 +17,7 @@ 
    <https://www.gnu.org/licenses/>.  */
 
 #include <sysdep.h>
+#include <kernel-features.h>
 #include <errno.h>
 #include <time.h>
 #include "kernel-posix-cpu-timers.h"
@@ -30,10 +31,51 @@ 
 
 /* Get current value of CLOCK and store it in TP.  */
 int
+__clock_gettime64 (clockid_t clock_id, struct __timespec64 *tp)
+{
+#ifdef __ASSUME_TIME64_SYSCALLS
+# ifndef __NR_clock_gettime64
+#  define __NR_clock_gettime64   __NR_clock_gettime
+#  define __vdso_clock_gettime64 __vdso_clock_gettime
+# endif
+   return INLINE_VSYSCALL (clock_gettime64, 2, clock_id, tp);
+#else
+# if defined HAVE_CLOCK_GETTIME64_VSYSCALL
+  int ret64 = INLINE_VSYSCALL (clock_gettime64, 2, clock_id, tp);
+  if (ret64 == 0 || errno != ENOSYS)
+    return ret64;
+# endif
+  struct timespec tp32;
+  int ret = INLINE_VSYSCALL (clock_gettime, 2, clock_id, &tp32);
+  if (ret == 0)
+    *tp = valid_timespec_to_timespec64 (tp32);
+  return ret;
+#endif
+}
+
+#if __TIMESIZE != 64
+int
 __clock_gettime (clockid_t clock_id, struct timespec *tp)
 {
-  return INLINE_VSYSCALL (clock_gettime, 2, clock_id, tp);
+  int ret;
+  struct __timespec64 tp64;
+
+  ret = __clock_gettime64 (clock_id, &tp64);
+
+  if (ret == 0)
+    {
+      if (! in_time_t_range (tp64.tv_sec))
+        {
+          __set_errno (EOVERFLOW);
+          return -1;
+        }
+
+      *tp = valid_timespec64_to_timespec (tp64);
+    }
+
+  return ret;
 }
+#endif
 libc_hidden_def (__clock_gettime)
 
 versioned_symbol (libc, __clock_gettime, clock_gettime, GLIBC_2_17);