Re: [PATCH v5] sysdeps/clock_nanosleep: Use clock_nanosleep_time64 if avaliable

[Adhemerval Zanella <adhemerval.zanella@linaro.org>]

On 07/11/2019 15:11, Alistair Francis wrote:
> The clock_nanosleep syscall is not supported on newer 32-bit platforms (such
> as RV32). To fix this issue let's use clock_nanosleep_time64 if it is
> avaliable.
> ---
> 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
> 
> v5:
>  - Fix clock_nanosleep syscall
>  - Rebase on master
> 
> v4:
>  - Rebase on master
>  - Use __clock_nanosleep to avoid duplicate implementations
>  - Fix the error handling when a syscall fails
> v2:
>  - Explicitly include `#include <kernel-features.h>`
> 
>  include/time.h                            | 20 +++++++
>  sysdeps/unix/sysv/linux/clock_nanosleep.c | 66 +++++++++++++++++++++--
>  2 files changed, 81 insertions(+), 5 deletions(-)
> 
> diff --git a/include/time.h b/include/time.h
> index b3e635395db..03389bda290 100644
> --- a/include/time.h
> +++ b/include/time.h
> @@ -209,6 +209,26 @@ libc_hidden_proto (__difftime64)
>  
>  extern double __difftime (time_t time1, time_t time0);
>  
> +#if __TIMESIZE == 64
> +# define __thrd_sleep_time64 thrd_sleep

I think it should be on its own patch.

> +# define __clock_nanosleep_time64 __clock_nanosleep
> +# define __nanosleep_time64 __nanosleep

Same as before.

> +# define __nanosleep_nocancel_time64 __nanosleep_nocancel

There is no need to redirect this inexistent symbol.

> +#else
> +extern int __thrd_sleep_time64 (const struct __timespec64* time_point,
> +                                struct __timespec64* remaining);

As before.

> +libc_hidden_proto (__thrd_sleep_time64)
> +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 __nanosleep_time64 (const struct __timespec64 *requested_time,
> +                                struct __timespec64 *remaining);

As before.

> +libc_hidden_proto (__nanosleep_time64)
> +extern int __nanosleep_nocancel_time64 (const struct __timespec64 *requested_time,
> +                                        struct __timespec64 *remaining);
> +libc_hidden_proto (__nanosleep_nocancel_time64)

As before.

> +#endif
>  
>  /* Use in the clock_* functions.  Size of the field representing the
>     actual clock ID.  */
> diff --git a/sysdeps/unix/sysv/linux/clock_nanosleep.c b/sysdeps/unix/sysv/linux/clock_nanosleep.c
> index f3c6fd2d5f7..7212dcf9c6d 100644
> --- a/sysdeps/unix/sysv/linux/clock_nanosleep.c
> +++ b/sysdeps/unix/sysv/linux/clock_nanosleep.c
> @@ -16,6 +16,7 @@
>     <https://www.gnu.org/licenses/>.  */
>  
>  #include <time.h>
> +#include <kernel-features.h>
>  #include <errno.h>
>  
>  #include <sysdep-cancel.h>
> @@ -26,9 +27,11 @@
>  /* We can simply use the syscall.  The CPU clocks are not supported
>     with this function.  */
>  int
> -__clock_nanosleep (clockid_t clock_id, int flags, const struct timespec *req,
> -		   struct timespec *rem)
> +__clock_nanosleep_time64 (clockid_t clock_id, int flags, const struct __timespec64 *req,
> +                          struct __timespec64 *rem)
>  {
> +  int r;
> +
>    if (clock_id == CLOCK_THREAD_CPUTIME_ID)
>      return EINVAL;
>    if (clock_id == CLOCK_PROCESS_CPUTIME_ID)

Ok.

> @@ -37,11 +40,64 @@ __clock_nanosleep (clockid_t clock_id, int flags, const struct timespec *req,
>    /* If the call is interrupted by a signal handler or encounters an error,
>       it returns a positive value similar to errno.  */
>    INTERNAL_SYSCALL_DECL (err);
> -  int r = INTERNAL_SYSCALL_CANCEL (clock_nanosleep, err, clock_id, flags,
> -				   req, rem);
> +
> +#ifdef __ASSUME_TIME64_SYSCALLS
> +# ifndef __NR_clock_nanosleep_time64
> +#  define __NR_clock_nanosleep_time64 __NR_clock_nanosleep
> +# endif
> +  r = INTERNAL_SYSCALL_CANCEL (clock_nanosleep_time64, err, clock_id,
> +                               flags, req, rem);

Ok.

> +#else
> +# ifdef __NR_clock_nanosleep_time64
> +  r = INTERNAL_SYSCALL_CANCEL (clock_nanosleep_time64, err, clock_id,
> +                               flags, req, rem);
> +
> +  if (r == 0 || errno != ENOSYS)
> +    {
> +      return (INTERNAL_SYSCALL_ERROR_P (r, err)
> +              ? INTERNAL_SYSCALL_ERRNO (r, err) : 0);
> +    }

Ok.

> +# endif /* __NR_clock_nanosleep_time64 */
> +  struct timespec ts32, tr32;
> +
> +  if (! in_time_t_range (req->tv_sec))
> +    {
> +      __set_errno (EOVERFLOW);
> +      return -1;
> +    }
> +
> +  ts32 = valid_timespec64_to_timespec (*req);
> +  r =  INTERNAL_SYSCALL_CANCEL (clock_nanosleep, err, clock_id, flags,
> +                                &ts32, &tr32);
> +
> +  if ((r == 0 || errno != ENOSYS) && rem)
> +    *rem = valid_timespec_to_timespec64 (tr32);

I think we can assume __NR_nanosleep here.

> +#endif /* __ASSUME_TIME64_SYSCALLS */
> +
>    return (INTERNAL_SYSCALL_ERROR_P (r, err)
> -	  ? INTERNAL_SYSCALL_ERRNO (r, err) : 0);
> +          ? INTERNAL_SYSCALL_ERRNO (r, err) : 0);
>  }

This is just replacing a tab with spaces, I don't think it is really required.

> +
> +#if __TIMESIZE != 64
> +int
> +__clock_nanosleep (clockid_t clock_id, int flags, const struct timespec *req,
> +                   struct timespec *rem)
> +{
> +  int r;
> +  struct __timespec64 treq64, trem64;
> +
> +  treq64 = valid_timespec_to_timespec64 (*req);
> +  r = __clock_nanosleep_time64 (clock_id, flags, &treq64, &trem64);
> +
> +  if (r == 0 || errno != ENOSYS)
> +    {
> +      if (rem)
> +        *rem = valid_timespec64_to_timespec (trem64);

Wouldn't we copy uninitialised data for EINVAL/ENOTSUPP/EFAULT?

> +    }
> +
> +  return r;
> +}
> +#endif
>  libc_hidden_def (__clock_nanosleep)
>  versioned_symbol (libc, __clock_nanosleep, clock_nanosleep, GLIBC_2_17);
>  /* clock_nanosleep moved to libc in version 2.17;
> 

Ok