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
7 /*
8 * The semid64_ds structure for x86 architecture.
9 * Note extra padding because this structure is passed back and forth
10 * between kernel and user space.
11 *
12 * semid64_ds was originally meant to be architecture specific, but
13 * everyone just ended up making identical copies without specific
14 * optimizations, so we may just as well all use the same one.
15 *
16 * 64 bit architectures use a 64-bit __kernel_time_t here, while
17 * 32 bit architectures have a pair of unsigned long values.
18 * so they do not need the first two padding words.
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 __kernel_time_t sem_otime; /* last semop time */
33 __kernel_time_t 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 */