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 most architectures (though it came from x86_32
10  * originally). Note extra padding because this structure is passed back and
11  * forth 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 */
46