[16/23] linux: Add time64 pselect support

  The syscall __NR_pselect6_time64 (32-bit) or __NR_pselect6 (64-bit)
is used as default.  For architectures with __ASSUME_TIME64_SYSCALLS
the 32-bit fallback uses __NR_pselec6.

To accomodate microblaze missing pselect6 support on kernel older
than 3.15 the fallback is moved to its own function to the microblaze
specific implementation can override it.

Checked on x86_64-linux-gnu and i686-linux-gnu (on 5.4 and on 4.15
kernel).
---
 include/sys/select.h                         | 10 +++
 sysdeps/unix/sysv/linux/microblaze/pselect.c | 38 ++++------
 sysdeps/unix/sysv/linux/pselect.c            | 80 +++++++++++++++++---
 3 files changed, 93 insertions(+), 35 deletions(-)
  

Ping.

On 13/07/2020 14:10, Adhemerval Zanella wrote:
> The syscall __NR_pselect6_time64 (32-bit) or __NR_pselect6 (64-bit)
> is used as default.  For architectures with __ASSUME_TIME64_SYSCALLS
> the 32-bit fallback uses __NR_pselec6.
> 
> To accomodate microblaze missing pselect6 support on kernel older
> than 3.15 the fallback is moved to its own function to the microblaze
> specific implementation can override it.
> 
> Checked on x86_64-linux-gnu and i686-linux-gnu (on 5.4 and on 4.15
> kernel).
> ---
>  include/sys/select.h                         | 10 +++
>  sysdeps/unix/sysv/linux/microblaze/pselect.c | 38 ++++------
>  sysdeps/unix/sysv/linux/pselect.c            | 80 +++++++++++++++++---
>  3 files changed, 93 insertions(+), 35 deletions(-)
> 
> diff --git a/include/sys/select.h b/include/sys/select.h
> index 07bb49b994..460dee9295 100644
> --- a/include/sys/select.h
> +++ b/include/sys/select.h
> @@ -3,6 +3,16 @@
>  
>  #ifndef _ISOMAC
>  /* Now define the internal interfaces.  */
> +# if __TIMESIZE == 64
> +#  define __pselect64 __pselect
> +#else
> +# include <struct___timespec64.h>
> +extern int __pselect64 (int __nfds, fd_set *__readfds,
> +			fd_set *__writefds, fd_set *__exceptfds,
> +			const struct __timespec64 *__timeout,
> +			const __sigset_t *__sigmask);
> +libc_hidden_proto (__pselect64)
> +#endif
>  extern int __pselect (int __nfds, fd_set *__readfds,
>  		      fd_set *__writefds, fd_set *__exceptfds,
>  		      const struct timespec *__timeout,
> diff --git a/sysdeps/unix/sysv/linux/microblaze/pselect.c b/sysdeps/unix/sysv/linux/microblaze/pselect.c
> index 1dfc3b8fc9..e73a98e178 100644
> --- a/sysdeps/unix/sysv/linux/microblaze/pselect.c
> +++ b/sysdeps/unix/sysv/linux/microblaze/pselect.c
> @@ -23,38 +23,27 @@
>  #include <sysdep-cancel.h>
>  
>  #ifndef __ASSUME_PSELECT
> -# define __pselect __pselect_syscall
> -#endif
> -
> -/* If pselect is supported, just use the Linux generic implementation.  */
> -#include <sysdeps/unix/sysv/linux/pselect.c>
> -
> -#ifndef __ASSUME_PSELECT
> -# undef __pselect
> -int
> -__pselect (int nfds, fd_set *readfds, fd_set *writefds, fd_set *exceptfds,
> -	   const struct timespec *timeout, const sigset_t *sigmask)
> +static int
> +__pselect64_fallback (int nfds, fd_set *readfds, fd_set *writefds,
> +		      fd_set *exceptfds, const struct __timespec64 *timeout,
> +		      const sigset_t *sigmask)
>  {
> -  int ret = __pselect_syscall (nfds, readfds, writefds, exceptfds, timeout,
> -			       sigmask);
> -  if (ret >= 0 || errno != ENOSYS)
> -    return ret;
> -
>    /* The fallback uses 'select' which shows the race condition regarding
>       signal mask set/restore, requires two additional syscalls, and has
>       a worse timeout precision (microseconds instead of nanoseconds).  */
>  
> -  struct timeval tval, *ptval = NULL;
> +  struct timeval tv32, *ptv32 = NULL;
>    if (timeout != NULL)
>      {
> -      if (! valid_nanoseconds (timeout->tv_nsec))
> +      if (! in_time_t_range (timeout->tv_sec)
> +	  || ! valid_nanoseconds (timeout->tv_nsec))
>  	{
>  	  __set_errno (EINVAL);
>  	  return -1;
>  	}
>  
> -      TIMESPEC_TO_TIMEVAL (&tval, timeout);
> -      ptval = &tval;
> +      tv32 = valid_timespec64_to_timeval (*timeout);
> +      ptv32 = &tv32;
>      }
>  
>    sigset_t savemask;
> @@ -62,12 +51,15 @@ __pselect (int nfds, fd_set *readfds, fd_set *writefds, fd_set *exceptfds,
>      __sigprocmask (SIG_SETMASK, sigmask, &savemask);
>  
>    /* select itself is a cancellation entrypoint.  */
> -  ret = __select (nfds, readfds, writefds, exceptfds, ptval);
> +  int r = __select (nfds, readfds, writefds, exceptfds, ptv32);
>  
>    if (sigmask != NULL)
>      __sigprocmask (SIG_SETMASK, &savemask, NULL);
>  
> -  return ret;
> +  return r;
>  }
> -weak_alias (__pselect, pselect)
> +# define PSELECT64_FALLBACK
>  #endif
> +
> +/* If pselect is supported, just use the Linux generic implementation.  */
> +#include <sysdeps/unix/sysv/linux/pselect.c>
> diff --git a/sysdeps/unix/sysv/linux/pselect.c b/sysdeps/unix/sysv/linux/pselect.c
> index 304db03338..c31a13767a 100644
> --- a/sysdeps/unix/sysv/linux/pselect.c
> +++ b/sysdeps/unix/sysv/linux/pselect.c
> @@ -18,14 +18,41 @@
>  
>  #include <sys/select.h>
>  #include <sysdep-cancel.h>
> +#include <time64-support.h>
> +
> +#if !defined (__ASSUME_TIME64_SYSCALLS) && !defined (PSELECT64_FALLBACK)
> +static int
> +__pselect64_fallback (int nfds, fd_set *readfds, fd_set *writefds,
> +		      fd_set *exceptfds, const struct __timespec64 *timeout,
> +		      const sigset_t *sigmask)
> +{
> +  struct timespec ts32, *pts32 = NULL;
> +  if (timeout != NULL)
> +    {
> +      if (! in_time_t_range (timeout->tv_sec))
> +	{
> +	  __set_errno (EINVAL);
> +	  return -1;
> +	}
> +
> +      ts32 = valid_timespec64_to_timespec (*timeout);
> +      pts32 = &ts32;
> +    }
> +
> +  return SYSCALL_CANCEL (pselect6, nfds, readfds, writefds, exceptfds,
> +			 pts32,
> +			 ((__syscall_ulong_t[]){ (uintptr_t) sigmask,
> +						 __NSIG_BYTES }));
> +}
> +#endif
>  
>  int
> -__pselect (int nfds, fd_set *readfds, fd_set *writefds, fd_set *exceptfds,
> -	   const struct timespec *timeout, const sigset_t *sigmask)
> +__pselect64 (int nfds, fd_set *readfds, fd_set *writefds, fd_set *exceptfds,
> +	     const struct __timespec64 *timeout, const sigset_t *sigmask)
>  {
>    /* The Linux kernel can in some situations update the timeout value.
>       We do not want that so use a local variable.  */
> -  struct timespec tval;
> +  struct __timespec64 tval;
>    if (timeout != NULL)
>      {
>        tval = *timeout;
> @@ -36,18 +63,47 @@ __pselect (int nfds, fd_set *readfds, fd_set *writefds, fd_set *exceptfds,
>       we can only pass in 6 directly.  If there is an architecture with
>       support for more parameters a new version of this file needs to
>       be created.  */
> -  struct
> -  {
> -    __syscall_ulong_t ss;
> -    __syscall_ulong_t ss_len;
> -  } data;
>  
> -  data.ss = (__syscall_ulong_t) (uintptr_t) sigmask;
> -  data.ss_len = __NSIG_BYTES;
> +#ifndef __NR_pselect6_time64
> +# define __NR_pselect6_time64 __NR_pselect6
> +#endif
> +  int r;
> +  if (supports_time64 ())
> +    {
> +      r = SYSCALL_CANCEL (pselect6_time64, nfds, readfds, writefds, exceptfds,
> +			  timeout,
> +			  ((__syscall_ulong_t[]){ (uintptr_t) sigmask,
> +						  __NSIG_BYTES }));
> +      if (r == 0 || errno != ENOSYS)
> +	return r;
>  
> -  return SYSCALL_CANCEL (pselect6, nfds, readfds, writefds, exceptfds,
> -                         timeout, &data);
> +      mark_time64_unsupported ();
> +    }
> +
> +#ifndef __ASSUME_TIME64_SYSCALLS
> +  r = __pselect64_fallback (nfds, readfds, writefds, exceptfds, timeout,
> +			    sigmask);
> +#endif
> +  return r;
>  }
> +
> +#if __TIMESIZE != 64
> +libc_hidden_def (__pselect64)
> +
> +int
> +__pselect (int nfds, fd_set *readfds, fd_set *writefds, fd_set *exceptfds,
> +	   const struct timespec *timeout, const sigset_t *sigmask)
> +{
> +  struct __timespec64 ts64, *pts64 = NULL;
> +  if (timeout != NULL)
> +    {
> +      ts64 = valid_timespec_to_timespec64 (*timeout);
> +      pts64 = &ts64;
> +    }
> +  return __pselect64 (nfds, readfds, writefds, exceptfds, pts64, sigmask);
> +}
> +#endif
> +
>  #ifndef __pselect
>  weak_alias (__pselect, pselect)
>  #endif
>