include/uapi/asm-generic/sembuf.h

   1 /* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */
   2 #ifndef __ASM_GENERIC_SEMBUF_H
   3 #define __ASM_GENERIC_SEMBUF_H
   4
   5 #include <asm/bitsperlong.h>
   6 #include <asm/ipcbuf.h>
   7
   8 /*
   9  * The semid64_ds structure for x86 architecture.
  10  * Note extra padding because this structure is passed back and forth
  11  * between kernel and user space.
  12  *
  13  * semid64_ds was originally meant to be architecture specific, but
  14  * everyone just ended up making identical copies without specific
  15  * optimizations, so we may just as well all use the same one.
  16  *
  17  * 64 bit architectures use a 64-bit long time field here, while
  18  * 32 bit architectures have a pair of unsigned long values.
  19  *
  20  * On big-endian systems, the padding is in the wrong place for
  21  * historic reasons, so user space has to reconstruct a time_t
  22  * value using
  23  *
  24  * user_semid_ds.sem_otime = kernel_semid64_ds.sem_otime +
  25  *              ((long long)kernel_semid64_ds.sem_otime_high << 32)
  26  *
  27  * Pad space is left for 2 miscellaneous 32-bit values
  28  */
  29 struct semid64_ds {
  30         struct ipc64_perm sem_perm;     /* permissions .. see ipc.h */
  31 #if __BITS_PER_LONG == 64
  32         long            sem_otime;      /* last semop time */
  33         long            sem_ctime;      /* last change time */
  34 #else
  35         unsigned long   sem_otime;      /* last semop time */
  36         unsigned long   sem_otime_high;
  37         unsigned long   sem_ctime;      /* last change time */
  38         unsigned long   sem_ctime_high;
  39 #endif
  40         unsigned long   sem_nsems;      /* no. of semaphores in array */
  41         unsigned long   __unused3;
  42         unsigned long   __unused4;
  43 };
  44
  45 #endif /* __ASM_GENERIC_SEMBUF_H */