xref: /linux/include/uapi/linux/shm.h (revision 2a785996)
1 /* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */
2 #ifndef _UAPI_LINUX_SHM_H_
3 #define _UAPI_LINUX_SHM_H_
4 
5 #include <linux/ipc.h>
6 #include <linux/errno.h>
7 #include <asm-generic/hugetlb_encode.h>
8 #ifndef __KERNEL__
9 #include <unistd.h>
10 #endif
11 
12 /*
13  * SHMMNI, SHMMAX and SHMALL are default upper limits which can be
14  * modified by sysctl. The SHMMAX and SHMALL values have been chosen to
15  * be as large possible without facilitating scenarios where userspace
16  * causes overflows when adjusting the limits via operations of the form
17  * "retrieve current limit; add X; update limit". It is therefore not
18  * advised to make SHMMAX and SHMALL any larger. These limits are
19  * suitable for both 32 and 64-bit systems.
20  */
21 #define SHMMIN 1			 /* min shared seg size (bytes) */
22 #define SHMMNI 4096			 /* max num of segs system wide */
23 #define SHMMAX (ULONG_MAX - (1UL << 24)) /* max shared seg size (bytes) */
24 #define SHMALL (ULONG_MAX - (1UL << 24)) /* max shm system wide (pages) */
25 #define SHMSEG SHMMNI			 /* max shared segs per process */
26 
27 /* Obsolete, used only for backwards compatibility and libc5 compiles */
28 struct shmid_ds {
29 	struct ipc_perm		shm_perm;	/* operation perms */
30 	int			shm_segsz;	/* size of segment (bytes) */
31 	__kernel_old_time_t	shm_atime;	/* last attach time */
32 	__kernel_old_time_t	shm_dtime;	/* last detach time */
33 	__kernel_old_time_t	shm_ctime;	/* last change time */
34 	__kernel_ipc_pid_t	shm_cpid;	/* pid of creator */
35 	__kernel_ipc_pid_t	shm_lpid;	/* pid of last operator */
36 	unsigned short		shm_nattch;	/* no. of current attaches */
37 	unsigned short 		shm_unused;	/* compatibility */
38 	void 			*shm_unused2;	/* ditto - used by DIPC */
39 	void			*shm_unused3;	/* unused */
40 };
41 
42 /* Include the definition of shmid64_ds and shminfo64 */
43 #include <asm/shmbuf.h>
44 
45 /*
46  * shmget() shmflg values.
47  */
48 /* The bottom nine bits are the same as open(2) mode flags */
49 #define SHM_R		0400	/* or S_IRUGO from <linux/stat.h> */
50 #define SHM_W		0200	/* or S_IWUGO from <linux/stat.h> */
51 /* Bits 9 & 10 are IPC_CREAT and IPC_EXCL */
52 #define SHM_HUGETLB	04000	/* segment will use huge TLB pages */
53 #define SHM_NORESERVE	010000	/* don't check for reservations */
54 
55 /*
56  * Huge page size encoding when SHM_HUGETLB is specified, and a huge page
57  * size other than the default is desired.  See hugetlb_encode.h
58  */
59 #define SHM_HUGE_SHIFT	HUGETLB_FLAG_ENCODE_SHIFT
60 #define SHM_HUGE_MASK	HUGETLB_FLAG_ENCODE_MASK
61 
62 #define SHM_HUGE_64KB	HUGETLB_FLAG_ENCODE_64KB
63 #define SHM_HUGE_512KB	HUGETLB_FLAG_ENCODE_512KB
64 #define SHM_HUGE_1MB	HUGETLB_FLAG_ENCODE_1MB
65 #define SHM_HUGE_2MB	HUGETLB_FLAG_ENCODE_2MB
66 #define SHM_HUGE_8MB	HUGETLB_FLAG_ENCODE_8MB
67 #define SHM_HUGE_16MB	HUGETLB_FLAG_ENCODE_16MB
68 #define SHM_HUGE_32MB	HUGETLB_FLAG_ENCODE_32MB
69 #define SHM_HUGE_256MB	HUGETLB_FLAG_ENCODE_256MB
70 #define SHM_HUGE_512MB	HUGETLB_FLAG_ENCODE_512MB
71 #define SHM_HUGE_1GB	HUGETLB_FLAG_ENCODE_1GB
72 #define SHM_HUGE_2GB	HUGETLB_FLAG_ENCODE_2GB
73 #define SHM_HUGE_16GB	HUGETLB_FLAG_ENCODE_16GB
74 
75 /*
76  * shmat() shmflg values
77  */
78 #define	SHM_RDONLY	010000	/* read-only access */
79 #define	SHM_RND		020000	/* round attach address to SHMLBA boundary */
80 #define	SHM_REMAP	040000	/* take-over region on attach */
81 #define	SHM_EXEC	0100000	/* execution access */
82 
83 /* super user shmctl commands */
84 #define SHM_LOCK 	11
85 #define SHM_UNLOCK 	12
86 
87 /* ipcs ctl commands */
88 #define SHM_STAT	13
89 #define SHM_INFO	14
90 #define SHM_STAT_ANY    15
91 
92 /* Obsolete, used only for backwards compatibility */
93 struct	shminfo {
94 	int shmmax;
95 	int shmmin;
96 	int shmmni;
97 	int shmseg;
98 	int shmall;
99 };
100 
101 struct shm_info {
102 	int used_ids;
103 	__kernel_ulong_t shm_tot;	/* total allocated shm */
104 	__kernel_ulong_t shm_rss;	/* total resident shm */
105 	__kernel_ulong_t shm_swp;	/* total swapped shm */
106 	__kernel_ulong_t swap_attempts;
107 	__kernel_ulong_t swap_successes;
108 };
109 
110 
111 #endif /* _UAPI_LINUX_SHM_H_ */
112