Re: [PATCH v6 3/3] sysv: linux: Pass 64-bit version of semctl syscall

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

On 29/04/2020 20:24, Alistair Francis wrote:
> On Wed, Apr 29, 2020 at 2:09 PM Adhemerval Zanella
> <adhemerval.zanella@linaro.org> wrote:
>>
>>
>>
>> On 28/04/2020 19:05, Alistair Francis via Libc-alpha wrote:
>>> The semctl_syscall() function passes a union semun to the kernel. The
>>> union includes struct semid_ds as a member. On 32-bit architectures the
>>> Linux kernel provides a *_high version of the 32-bit sem_otime and
>>> sem_ctime values. These can be combined to get a 64-bit version of the
>>> time.
>>>
>>> This patch adjusts the struct semid_ds to support the *_high versions
>>> of sem_otime and sem_ctime. For 32-bit systems with a 64-bit time_t
>>> this can be used to get a 64-bit time from the two 32-bit values.
>>>
>>> Due to alignment differences between 64-bit and 32-bit variables we
>>> also need to set nsems to ensure it's correct.
>>
>> I think this approach might trigger an issue on semid_ds definition for
>> time64 that I only noticed now.
>>
>> Since the idea of semctl is not use a different entrypoint neither to add
>> aditional flag when issuing the syscall (either semctl or ipc), with this
>> change we need to assure that __TIMESIZE == 32 sem_otime alignment matches
>> __TIMESIZE == 64 one.
> 
> I don't follow. We don't assume that sem_otime has the same allignment
> for __TIMESIZE == 32 and 64. In fact for RV32 they are not alligned
> the same.
> 
>>
>> However for semid_ds and msqid_ds time_t members can't not properly aligned
>> to be expanded to 64-bit (shmid_ds has a shm_segsz field before the
>> timestamp fields) due to the ipc_perm header consisting of 9 32-bit words
>> except on parisc/powerpc/sparc.  The alignment difference will make
>> semctl once programs states build against a semid_ds with time_t
>> being an 64-bit type.
> 
> I am missing something here as well, as that is exactly what RV32 is
> testing and the glibc tests are passing (and a LInux rootFS boots).

The issue is for architectures that might select the __TIMESIZE at build
time, so two different semid_ds structure might be used with semctl.
For instance, on arm with current scheme:

For __TIMESIZE == 32:
  sizeof (struct ipc_perm):              36
  sizeof (struct semid_ds):              72
  offsetof (struct semid_ds, sem_perm):  0
  offsetof (struct semid_ds, sem_otime): 40
  offsetof (struct semid_ds, sem_ctime): 48
  offsetof (struct semid_ds, sem_nsems): 56

For __TIMESIZE == 64:
  sizeof (struct ipc_perm):              36
  sizeof (struct semid_ds):              64
  offsetof (struct semid_ds, sem_perm):  0
  offsetof (struct semid_ds, sem_otime): 36
  offsetof (struct semid_ds, sem_ctime): 44
  offsetof (struct semid_ds, sem_nsems): 52

The syscall itself will use the expected structure, however the code:

  if (ret >= 0 && restore)
    {
      arg.buf = orig;
      arg.buf->sem_perm  = tmp.sem_perm;
      arg.buf->sem_otime = tmp.sem_otime
                           | ((time_t) tmp.sem_otime_high << 32);
      arg.buf->sem_ctime = tmp.sem_ctime
                           | ((time_t) tmp.sem_ctime_high << 32);
      arg.buf->sem_nsems = tmp.sem_nsems;

will write down the timestamps on wrong place for time64 timestamps.

This is not an issue for 32-bit architectures that does not have
support for 32-bit time_t (as RV32).

> 
>>
>> So we have 2 options here:
>>
>>   1. Keep the semid_ds layout as the kernel expected one and add the
>>      newer time64 timestamps at the *end*, and redefine the command
>>      arguments that passes a struct semid_ds to use
>>      (IPC_STAT, SEM_STAT, SEM_STAT_ANY) to indicate that the semid_ds
>>      is a time64 one.  The IPC_64 bit might be a feasible hack since
>>      kernel won't use on possible new commands.

This solution would require to redefine IPC_STAT, SEM_STAT, SEM_STAT_ANY to
a different value for when building for __TIMESIZE==64 on ABIs that support
its selection.  The easiest way would to parametrize the ipc commands
that handle per architecture:

   /* On each ABI that supports __TIMESIZE==32.  */
   #if __TIMESIZE == 64
   # define __IPC_CMD_TIME_64 0x100  /* Same as __IPC_64.  */
   #else
   # define __IPC_CMD_TIME_64 0x0
   #endif
   #define __IPC_TIME_64 1

If fro architecture only support __TIMESIZE64 (default):

   #define __IPC_CMD_TIME64 0x0
   #define __IPC_TIME_64    0

Then on Linux ipc.h:

   #define IPC_STAT         (2 | __IPC_CMD_TIME_64)

Same for sem.h:

   #define SEM_STAT        (18 | __IPC_CMD_TIME_64)
   #define SEM_STAT_ANY    (20 | __IPC_CMD_TIME_64)

Then on semctl.c (totally untested):

---
union semun
{ 
  int val;                      /* value for SETVAL */
#if __IPC_TIME_64
  struct __semid_ds32 *buf32;
#endif
  struct semid_ds *buf;         /* buffer for IPC_STAT & IPC_SET */
  unsigned short int *array;    /* array for GETALL & SETALL */
  struct seminfo *__buf;        /* buffer for IPC_INFO */
};

int
__new_semctl (int semid, int semnum, int cmd, ...)
{
  /* POSIX states ipc_perm mode should have type of mode_t.  */
  _Static_assert (sizeof ((struct semid_ds){0}.sem_perm.mode)
                  == sizeof (mode_t),
                  "sizeof (msqid_ds.msg_perm.mode) != sizeof (mode_t)");

  union semun arg = { 0 };
  va_list ap;

  /* Get the argument only if required.  Ignore the __IPC_STAT_64.  */
  switch (cmd & ~__IPC_CMD_TIME_64)
    {
    case SETVAL:                        /* arg.val */
    case GETALL:                        /* arg.array */
    case SETALL:
    case IPC_STAT & ~__IPC_CMD_TIME_64: /* arg.buf */
    case IPC_SET:
    case SEM_STAT & ~__IPC_CMD_TIME_64:
    case IPC_INFO:                      /* arg.__buf */
    case SEM_INFO:
      va_start (ap, cmd);
      arg = va_arg (ap, union semun);
      va_end (ap);
      break;
    }

#ifdef __IPC_TIME_64
  struct __semid_ds32 tmp32;
  struct __semid_ds64 *orig64;
  if (cmd & __IPC_STAT_64)
    {
       tmp32 = (struct __semid_ds32) { 0 };
       orig64 = (struct __semid_ds64 *) arg.buf;
       arg.buf32 = tmp32;
    }
#endif

#ifdef __ASSUME_SYSVIPC_BROKEN_MODE_T
  struct semid_ds tmpds;
  if (cmd == IPC_SET)
    {
      tmpds = *arg.buf;
      tmpds.sem_perm.mode *= 0x10000U;
      arg.buf = &tmpds;
    }
#endif

  int ret = semctl_syscall (semid, semnum, cmd & ~__IPC_CMD_TIME_64, arg);
  if (ret < 0)
    return ret;

  switch (cmd & ~__IPC_CMD_TIME_64)
    {
    case IPC_STAT:
    case SEM_STAT:
    case SEM_STAT_ANY:
#ifdef __ASSUME_SYSVIPC_BROKEN_MODE_T
# if __IPC_TIME_64
      arg.buf32->sem_perm.mode >>= 16;
# else
      arg.buf->sem_perm.mode >>= 16;
# endif
#else
      /* Old Linux kernel versions might not clear the mode padding.  */
      if (sizeof ((struct semid_ds){0}.sem_perm.mode)
          !  = sizeof (__kernel_mode_t))
# if __IPC_TIME_64
        arg.buf32->sem_perm.mode &= 0xFFFF;
# else
        arg.buf->sem_perm.mode &= 0xFFFF;
# endif
#endif
    }

#ifdef __IPC_TIME_64
  if (cmd & & ~__IPC_CMD_TIME_64)
    {
      orig64->sem_perm = tmp32.sem_perm;
      orig64->sem_otime = tmp32.sem_otime
			  | ((__time64_t) tmp32.sem_otime_high << 32);
      orig64->sem_ctime = tmp32.sem_ctime
			  | ((__time64_t) tmp32.sem_ctime_high << 32);
      orig64->sem_nsems = tmp32.sem_nsems;
      arg.buf = (struct semid_ds *) orig64;
    }
#endif

  return ret;
}
---

So basically:

  1. If an ABI issues 'semctl (semid, semnum, IPC_STAT, ...)' with 
     IPC_STAT without _IPC_CMD_TIME_64, the provided semid_ds buffe
     will be used directly on the syscall.  This is the case for
     64-bit architectures and 32-bit architecture without
     __TIMESIZE==32 support (RV32 for instance).

  2. If an ABI issues 'semctl (semid, semnum, IPC_STAT, ...)' with
     IPC_STAT with _IPC_CMD_TIME_64 then __TIMESIZE==64 is implied.
     A temporary __semid_ds32 will be used to issue the syscall and its
     contents will be copied to users semid_ds buffer (which is also
     implied to be the __TIMESIZE==64).

There is the requeriment to use define __semid_ds64 that uses __time64_t
explicitly for architecture that support __TIMESIZE==32.

(The handling of __ASSUME_SYSVIPC_BROKEN_MODE_T and the kernel issue
regarding sem_perm.mode clearing could be improved/simplified).

>>
>>   2. Add a new semctl64 to handle the time64 one semid_ds.
>>
>>> ---
>>>  .../unix/sysv/linux/hppa/struct__semid_ds32.h | 32 +++++++++++++
>>>  .../unix/sysv/linux/mips/struct__semid_ds32.h | 30 ++++++++++++
>>>  .../sysv/linux/powerpc/struct__semid_ds32.h   | 32 +++++++++++++
>>>  sysdeps/unix/sysv/linux/semctl.c              | 47 +++++++++++++++++--
>>>  .../sysv/linux/sparc/struct__semid_ds32.h     | 32 +++++++++++++
>>>  sysdeps/unix/sysv/linux/struct__semid_ds32.h  | 32 +++++++++++++
>>>  .../unix/sysv/linux/x86/struct__semid_ds32.h  | 32 +++++++++++++
>>>  7 files changed, 233 insertions(+), 4 deletions(-)
>>>  create mode 100644 sysdeps/unix/sysv/linux/hppa/struct__semid_ds32.h
>>>  create mode 100644 sysdeps/unix/sysv/linux/mips/struct__semid_ds32.h
>>>  create mode 100644 sysdeps/unix/sysv/linux/powerpc/struct__semid_ds32.h
>>>  create mode 100644 sysdeps/unix/sysv/linux/sparc/struct__semid_ds32.h
>>>  create mode 100644 sysdeps/unix/sysv/linux/struct__semid_ds32.h
>>>  create mode 100644 sysdeps/unix/sysv/linux/x86/struct__semid_ds32.h
>>>
>>> diff --git a/sysdeps/unix/sysv/linux/hppa/struct__semid_ds32.h b/sysdeps/unix/sysv/linux/hppa/struct__semid_ds32.h
>>> new file mode 100644
>>> index 0000000000..9eceaaff2d
>>> --- /dev/null
>>> +++ b/sysdeps/unix/sysv/linux/hppa/struct__semid_ds32.h
>>> @@ -0,0 +1,32 @@
>>> +/* HPPA implementation of the semaphore struct __semid_ds32.
>>> +   Copyright (C) 1995-2020 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
>>> +   <https://www.gnu.org/licenses/>.  */
>>> +
>>> +#if __WORDSIZE == 32
>>> +/* This is the "new" y2038 types defined after the 5.1 kernel. It allows
>>> +   the kernel to use {o,c}time{_high} values to support a 64-bit time_t.  */
>>> +struct __semid_ds32 {
>>> +  struct ipc_perm sem_perm;              /* operation permission struct */
>>> +  __syscall_ulong_t   sem_otime_high;    /* last semop() time high */
>>> +  __syscall_ulong_t   sem_otime;         /* last semop() time */
>>> +  __syscall_ulong_t   sem_ctime_high;    /* last time changed by semctl() high */
>>> +  __syscall_ulong_t   sem_ctime;         /* last time changed by semctl() */
>>> +  __syscall_ulong_t   sem_nsems;         /* number of semaphores in set */
>>> +  __syscall_ulong_t   __glibc_reserved3;
>>> +  __syscall_ulong_t   __glibc_reserved4;
>>> +};
>>> +#endif
>>
>> No need to define it for __WORDSIZE == 32, the ABI just supports it
>> anyway.
> 
> Ok, I have removed these.
> 
>>
>>> diff --git a/sysdeps/unix/sysv/linux/mips/struct__semid_ds32.h b/sysdeps/unix/sysv/linux/mips/struct__semid_ds32.h
>>> new file mode 100644
>>> index 0000000000..2e3e2fc562
>>> --- /dev/null
>>> +++ b/sysdeps/unix/sysv/linux/mips/struct__semid_ds32.h
>>> @@ -0,0 +1,30 @@
>>> +/* MIPS implementation of the semaphore struct __semid_ds32.
>>> +   Copyright (C) 1995-2020 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
>>> +   <https://www.gnu.org/licenses/>.  */
>>> +
>>> +#if __WORDSIZE == 32
>>> +/* This is the "new" y2038 types defined after the 5.1 kernel. It allows
>>> +   the kernel to use {o,c}time{_high} values to support a 64-bit time_t.  */
>>> +struct __semid_ds32 {
>>> +  struct ipc_perm sem_perm;              /* operation permission struct */
>>> +  __syscall_ulong_t   sem_otime;         /* last semop time */
>>> +  __syscall_ulong_t   sem_ctime;         /* last change time */
>>> +  __syscall_ulong_t   sem_nsems;         /* number of semaphores in set */
>>> +  __syscall_ulong_t   sem_otime_high;
>>> +  __syscall_ulong_t   sem_ctime_high;
>>> +};
>>> +#endif
>>
>> Ok, it cover mips64-n32 as well.
>>
>>> diff --git a/sysdeps/unix/sysv/linux/powerpc/struct__semid_ds32.h b/sysdeps/unix/sysv/linux/powerpc/struct__semid_ds32.h
>>> new file mode 100644
>>> index 0000000000..f509db5a02
>>> --- /dev/null
>>> +++ b/sysdeps/unix/sysv/linux/powerpc/struct__semid_ds32.h
>>> @@ -0,0 +1,32 @@
>>> +/* PowerPC implementation of the semaphore struct __semid_ds32.
>>> +   Copyright (C) 1995-2020 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
>>> +   <https://www.gnu.org/licenses/>.  */
>>> +
>>> +#if __WORDSIZE == 32
>>> +/* This is the "new" y2038 types defined after the 5.1 kernel. It allows
>>> +   the kernel to use {o,c}time{_high} values to support a 64-bit time_t.  */
>>> +struct __semid_ds32 {
>>> +  struct ipc_perm sem_perm;              /* operation permission struct */
>>> +  __syscall_ulong_t   sem_otime_high;    /* last semop() time high */
>>> +  __syscall_ulong_t   sem_otime;         /* last semop() time */
>>> +  __syscall_ulong_t   sem_ctime_high;    /* last time changed by semctl() high */
>>> +  __syscall_ulong_t   sem_ctime;         /* last time changed by semctl() */
>>> +  __syscall_ulong_t   sem_nsems;         /* number of semaphores in set */
>>> +  __syscall_ulong_t   __glibc_reserved3;
>>> +  __syscall_ulong_t   __glibc_reserved4;
>>> +};
>>> +#endif
>>
>> Ok.
>>
>>> diff --git a/sysdeps/unix/sysv/linux/semctl.c b/sysdeps/unix/sysv/linux/semctl.c
>>> index 30571af49f..0634cc1abe 100644
>>> --- a/sysdeps/unix/sysv/linux/semctl.c
>>> +++ b/sysdeps/unix/sysv/linux/semctl.c
>>> @@ -22,8 +22,13 @@
>>>  #include <sysdep.h>
>>>  #include <shlib-compat.h>
>>>  #include <errno.h>
>>> +#include <struct__semid_ds32.h>
>>>  #include <linux/posix_types.h>  /* For __kernel_mode_t.  */
>>>
>>> +#define IPC_TIME64 \
>>> + (__WORDSIZE == 32 && __TIMESIZE == 64 \
>>> +     && (!defined __SYSCALL_WORDSIZE || __SYSCALL_WORDSIZE == 32))
>>
>> I think it would be better to move this definition to the common
>> ipc_priv.h header since it will most likely be used on msgctl
>> and shmctl y2038 support as well.
> 
> Done.
> 
>>
>>> +
>>>  /* Define a `union semun' suitable for Linux here.  */
>>>  union semun
>>>  {
>>> @@ -44,13 +49,47 @@ union semun
>>>  static int
>>>  semctl_syscall (int semid, int semnum, int cmd, union semun arg)
>>>  {
>>> +  int ret;
>>> +#if IPC_TIME64
>>
>> I think we shoul add a comment stating why we need a auxiliary buffer
>> for STAT/STAT_ANY operations.  Something like:
>>
>>    A temporary buffer is used to avoid both an issue where the export
>>    semid_ds might not have follow kernel expected layout (due
>>    sem_{o,c}time alignment in 64-bit time case) and the issue where
>>    some kernel version might not clear the high bits when returning
>>    then sem_{o,c}time information.
> 
> Added
> 
>>
>>> +  struct __semid_ds32 tmp;
>>> +  struct semid_ds *orig;
>>> +  bool restore = false;
>>> +  if (cmd == IPC_STAT || cmd == SEM_STAT || cmd == SEM_STAT_ANY)
>>> +    {
>>> +      tmp = (struct __semid_ds32) {
>>> +        .sem_perm  = arg.buf->sem_perm,
>>> +        .sem_otime = arg.buf->sem_otime,
>>> +        .sem_ctime = arg.buf->sem_ctime,
>>> +        .sem_nsems = arg.buf->sem_nsems,
>>> +      };
>>
>> We need to fully initialize the temporary struct to avoid a kernel
>> issue fixed in 4693916846269d633a3664586650dbfac2c5562f (4.14) where
>> kernel does not clear the timestamps high bits.
> 
> Added.
> 
>>
>>> +      orig = arg.buf;
>>> +      arg.buf = (struct semid_ds*)&tmp;
>>
>> Space before &tmp.
> 
> Added.
> 
>>
>>> +      restore = true;
>>> +    }
>>> +#endif
>>> +
>>>  #ifdef __ASSUME_DIRECT_SYSVIPC_SYSCALLS
>>> -  return INLINE_SYSCALL_CALL (semctl, semid, semnum, cmd | __IPC_64,
>>> -                           arg.array);
>>> +  ret = INLINE_SYSCALL_CALL (semctl, semid, semnum, cmd | __IPC_64,
>>> +                             arg.array);
>>>  #else
>>> -  return INLINE_SYSCALL_CALL (ipc, IPCOP_semctl, semid, semnum, cmd | __IPC_64,
>>> -                           SEMCTL_ARG_ADDRESS (arg));
>>> +  ret = INLINE_SYSCALL_CALL (ipc, IPCOP_semctl, semid, semnum, cmd | __IPC_64,
>>> +                             SEMCTL_ARG_ADDRESS (arg));
>>>  #endif
>>
>> Ok.
>>
>>> +
>>> +#if IPC_TIME64
>>> +  if (ret >= 0 && restore)
>>> +    {
>>> +      arg.buf = orig;
>>> +      arg.buf->sem_perm  = tmp.sem_perm;
>>> +      arg.buf->sem_otime = tmp.sem_otime
>>> +                           | ((time_t) tmp.sem_otime_high << 32);
>>> +      arg.buf->sem_ctime = tmp.sem_ctime
>>> +                           | ((time_t) tmp.sem_ctime_high << 32);
>>> +      arg.buf->sem_nsems = tmp.sem_nsems;
>>
>> I think it would be better to use __time64_t explicit here.
> 
> Done.
> 
> Alistair
> 
>>
>>> +    }
>>> +#endif
>>> +
>>> +    return ret;
>>>  }
>>>
>>>  int
>>> diff --git a/sysdeps/unix/sysv/linux/sparc/struct__semid_ds32.h b/sysdeps/unix/sysv/linux/sparc/struct__semid_ds32.h
>>> new file mode 100644
>>> index 0000000000..f641825d37
>>> --- /dev/null
>>> +++ b/sysdeps/unix/sysv/linux/sparc/struct__semid_ds32.h
>>> @@ -0,0 +1,32 @@
>>> +/* Sparc implementation of the semaphore struct __semid_ds32.
>>> +   Copyright (C) 1995-2020 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
>>> +   <https://www.gnu.org/licenses/>.  */
>>> +
>>> +#if __WORDSIZE == 32
>>> +/* This is the "new" y2038 types defined after the 5.1 kernel. It allows
>>> +   the kernel to use {o,c}time{_high} values to support a 64-bit time_t.  */
>>> +struct __semid_ds32 {
>>> +  struct ipc_perm sem_perm;              /* operation permission struct */
>>> +  __syscall_ulong_t   sem_otime_high;    /* last semop() time high */
>>> +  __syscall_ulong_t   sem_otime;         /* last semop() time */
>>> +  __syscall_ulong_t   sem_ctime_high;    /* last time changed by semctl() high */
>>> +  __syscall_ulong_t   sem_ctime;         /* last time changed by semctl() */
>>> +  __syscall_ulong_t   sem_nsems;         /* number of semaphores in set */
>>> +  __syscall_ulong_t   __glibc_reserved3;
>>> +  __syscall_ulong_t   __glibc_reserved4;
>>> +};
>>> +#endif
>>
>> Ok.
>>
>>> diff --git a/sysdeps/unix/sysv/linux/struct__semid_ds32.h b/sysdeps/unix/sysv/linux/struct__semid_ds32.h
>>> new file mode 100644
>>> index 0000000000..51ff83206d
>>> --- /dev/null
>>> +++ b/sysdeps/unix/sysv/linux/struct__semid_ds32.h
>>> @@ -0,0 +1,32 @@
>>> +/* Generic implementation of the semaphore struct __semid_ds32.
>>> +   Copyright (C) 1995-2020 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
>>> +   <https://www.gnu.org/licenses/>.  */
>>> +
>>> +#if __WORDSIZE == 32
>>> +/* This is the "new" y2038 types defined after the 5.1 kernel. It allows
>>> +   the kernel to use {o,c}time{_high} values to support a 64-bit time_t.  */
>>> +struct __semid_ds32 {
>>> +  struct ipc_perm sem_perm;              /* operation permission struct */
>>> +  __syscall_ulong_t   sem_otime;         /* last semop() time */
>>> +  __syscall_ulong_t   sem_otime_high;    /* last semop() time high */
>>> +  __syscall_ulong_t   sem_ctime;         /* last time changed by semctl() */
>>> +  __syscall_ulong_t   sem_ctime_high;    /* last time changed by semctl() high */
>>> +  __syscall_ulong_t   sem_nsems;         /* number of semaphores in set */
>>> +  __syscall_ulong_t   __glibc_reserved3;
>>> +  __syscall_ulong_t   __glibc_reserved4;
>>> +};
>>> +#endif
>>
>> Ok.
>>
>>> diff --git a/sysdeps/unix/sysv/linux/x86/struct__semid_ds32.h b/sysdeps/unix/sysv/linux/x86/struct__semid_ds32.h
>>> new file mode 100644
>>> index 0000000000..f65c9fc877
>>> --- /dev/null
>>> +++ b/sysdeps/unix/sysv/linux/x86/struct__semid_ds32.h
>>> @@ -0,0 +1,32 @@
>>> +/* x86 implementation of the semaphore struct __semid_ds32.
>>> +   Copyright (C) 1995-2020 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
>>> +   <https://www.gnu.org/licenses/>.  */
>>> +
>>> +#ifdef __i386__
>>> +/* This is the "new" y2038 types defined after the 5.1 kernel. It allows
>>> +   the kernel to use {o,c}time{_high} values to support a 64-bit time_t.  */
>>> +struct __semid_ds32 {
>>> +  struct ipc_perm sem_perm;              /* operation permission struct */
>>> +  __syscall_ulong_t   sem_otime;         /* last semop() time */
>>> +  __syscall_ulong_t   sem_otime_high;    /* last semop() time high */
>>> +  __syscall_ulong_t   sem_ctime;         /* last time changed by semctl() */
>>> +  __syscall_ulong_t   sem_ctime_high;    /* last time changed by semctl() high */
>>> +  __syscall_ulong_t   sem_nsems;         /* number of semaphores in set */
>>> +  __syscall_ulong_t   __glibc_reserved3;
>>> +  __syscall_ulong_t   __glibc_reserved4;
>>> +};
>>> +#endif
>>>
>>
>> Ok.
>>
>>