Re: [RFC v3 02/23] sysdeps/gettimeofday: Use clock_gettime64 if avaliable

[Lukasz Majewski <lukma at denx dot de>]

Hi Alistair,

> Not all architectures support the obsolete gettimeofday so use the
> newer clock_gettime64 syscall if it is avaliable. This fixes RV32
> build issues.
> 
> Signed-off-by: Alistair Francis <alistair.francis@wdc.com>
> ---
>  ChangeLog                              |  1 +
>  sysdeps/unix/sysv/linux/gettimeofday.c | 28
> ++++++++++++++++++++++++++ 2 files changed, 29 insertions(+)
> 
> diff --git a/ChangeLog b/ChangeLog
> index 477b9b49b3..9ca390a9c3 100644
> --- a/ChangeLog
> +++ b/ChangeLog
> @@ -1028,6 +1028,7 @@
>  	* nptl/thrd_sleep.c: Use clock_nanosleep_time64 instead of
> nanosleep.
>  	* sysdeps/unix/sysv/linux/nanosleep.c: Likewise.
>  	* sysdeps/unix/sysv/linux/nanosleep_nocancel.c: Likewise.
> +	* sysdeps/unix/sysv/linux/gettimeofday.c: Use
> clock_gettime64 syscall for gettimeofday. 
>  2019-06-20  Dmitry V. Levin  <ldv@altlinux.org>
>  	    Florian Weimer  <fweimer@redhat.com>
> diff --git a/sysdeps/unix/sysv/linux/gettimeofday.c
> b/sysdeps/unix/sysv/linux/gettimeofday.c index a74f03825a..151b1e606c
> 100644 --- a/sysdeps/unix/sysv/linux/gettimeofday.c
> +++ b/sysdeps/unix/sysv/linux/gettimeofday.c
> @@ -32,7 +32,35 @@
>  int
>  __gettimeofday (struct timeval *tv, struct timezone *tz)
>  {
> +#ifdef __ASSUME_TIME64_SYSCALLS

I'm not the glibc expert but according to [1], the
__ASSUME_TIME64_SYSCALLS will be defined also for __WORDSIZE = 64 archs.

This means that this code will be executed on x86_64 and return with an
ENOTSUPP error as those archs shall not define clock_gettime64 and
will just use the clock_settime.

Please consider re-using pattern from clock_settime conversion [2].

> +  int ret;
> +  struct __timespec64 now;
> +
> +  ret = INLINE_VSYSCALL (clock_gettime64, 2, CLOCK_REALTIME,
> +                         &now);
> +
> +  /* Convert from timespec to timeval */
> +  tv->tv_sec = now.tv_sec;
> +  tv->tv_usec = now.tv_nsec / 1000;
> +
> +  return ret;
> +#else
> +# ifdef __NR_clock_gettime64
> +  long int ret;
> +  struct __timespec64 now;
> +
> +  ret = INLINE_VSYSCALL (clock_gettime64, 2, CLOCK_REALTIME,
> +                         &now);
> +
> +  /* Convert from timespec to timeval */
> +  tv->tv_sec = now.tv_sec;
> +  tv->tv_usec = now.tv_nsec / 1000;
> +
> +  if (ret == 0 || errno != ENOSYS)
> +    return ret;
> +# endif
>    return INLINE_VSYSCALL (gettimeofday, 2, tv, tz);
> +#endif
>  }
>  libc_hidden_def (__gettimeofday)
>  weak_alias (__gettimeofday, gettimeofday)

Note:

[1] - 
https://github.com/lmajewski/y2038_glibc/commit/1fdbc6002101a78a8a6a076bbb642b3082c2225d

[2] -
https://github.com/lmajewski/y2038_glibc/commit/69f842a8519ca13ed11fab0ff1bcc6fa1a524192

Best regards,

Lukasz Majewski

--

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