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Release 4.15 include/uapi/linux/shm.h

/* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */
#ifndef _UAPI_LINUX_SHM_H_

#define _UAPI_LINUX_SHM_H_

#include <linux/ipc.h>
#include <linux/errno.h>
#include <asm-generic/hugetlb_encode.h>
#ifndef __KERNEL__
#include <unistd.h>
#endif

/*
 * SHMMNI, SHMMAX and SHMALL are default upper limits which can be
 * modified by sysctl. The SHMMAX and SHMALL values have been chosen to
 * be as large possible without facilitating scenarios where userspace
 * causes overflows when adjusting the limits via operations of the form
 * "retrieve current limit; add X; update limit". It is therefore not
 * advised to make SHMMAX and SHMALL any larger. These limits are
 * suitable for both 32 and 64-bit systems.
 */

#define SHMMIN 1			 
/* min shared seg size (bytes) */

#define SHMMNI 4096			 
/* max num of segs system wide */

#define SHMMAX (ULONG_MAX - (1UL << 24)) 
/* max shared seg size (bytes) */

#define SHMALL (ULONG_MAX - (1UL << 24)) 
/* max shm system wide (pages) */

#define SHMSEG SHMMNI			 
/* max shared segs per process */

/* Obsolete, used only for backwards compatibility and libc5 compiles */

struct shmid_ds {
	
struct ipc_perm		shm_perm;	/* operation perms */
	
int			shm_segsz;	/* size of segment (bytes) */
	
__kernel_time_t		shm_atime;	/* last attach time */
	
__kernel_time_t		shm_dtime;	/* last detach time */
	
__kernel_time_t		shm_ctime;	/* last change time */
	
__kernel_ipc_pid_t	shm_cpid;	/* pid of creator */
	
__kernel_ipc_pid_t	shm_lpid;	/* pid of last operator */
	
unsigned short		shm_nattch;	/* no. of current attaches */
	
unsigned short 		shm_unused;	/* compatibility */
	
void 			*shm_unused2;	/* ditto - used by DIPC */
	
void			*shm_unused3;	/* unused */
};

/* Include the definition of shmid64_ds and shminfo64 */
#include <asm/shmbuf.h>

/*
 * shmget() shmflg values.
 */
/* The bottom nine bits are the same as open(2) mode flags */

#define SHM_R		0400	
/* or S_IRUGO from <linux/stat.h> */

#define SHM_W		0200	
/* or S_IWUGO from <linux/stat.h> */
/* Bits 9 & 10 are IPC_CREAT and IPC_EXCL */

#define SHM_HUGETLB	04000	
/* segment will use huge TLB pages */

#define SHM_NORESERVE	010000	
/* don't check for reservations */

/*
 * Huge page size encoding when SHM_HUGETLB is specified, and a huge page
 * size other than the default is desired.  See hugetlb_encode.h
 */

#define SHM_HUGE_SHIFT	HUGETLB_FLAG_ENCODE_SHIFT

#define SHM_HUGE_MASK	HUGETLB_FLAG_ENCODE_MASK


#define SHM_HUGE_64KB	HUGETLB_FLAG_ENCODE_64KB

#define SHM_HUGE_512KB	HUGETLB_FLAG_ENCODE_512KB

#define SHM_HUGE_1MB	HUGETLB_FLAG_ENCODE_1MB

#define SHM_HUGE_2MB	HUGETLB_FLAG_ENCODE_2MB

#define SHM_HUGE_8MB	HUGETLB_FLAG_ENCODE_8MB

#define SHM_HUGE_16MB	HUGETLB_FLAG_ENCODE_16MB

#define SHM_HUGE_256MB	HUGETLB_FLAG_ENCODE_256MB

#define SHM_HUGE_1GB	HUGETLB_FLAG_ENCODE_1GB

#define SHM_HUGE_2GB	HUGETLB_FLAG_ENCODE_2GB

#define SHM_HUGE_16GB	HUGETLB_FLAG_ENCODE_16GB

/*
 * shmat() shmflg values
 */

#define	SHM_RDONLY	010000	
/* read-only access */

#define	SHM_RND		020000	
/* round attach address to SHMLBA boundary */

#define	SHM_REMAP	040000	
/* take-over region on attach */

#define	SHM_EXEC	0100000	
/* execution access */

/* super user shmctl commands */

#define SHM_LOCK 	11

#define SHM_UNLOCK 	12

/* ipcs ctl commands */

#define SHM_STAT 	13

#define SHM_INFO 	14

/* Obsolete, used only for backwards compatibility */

struct	shminfo {
	
int shmmax;
	
int shmmin;
	
int shmmni;
	
int shmseg;
	
int shmall;
};


struct shm_info {
	
int used_ids;
	
__kernel_ulong_t shm_tot;	/* total allocated shm */
	
__kernel_ulong_t shm_rss;	/* total resident shm */
	
__kernel_ulong_t shm_swp;	/* total swapped shm */
	
__kernel_ulong_t swap_attempts;
	
__kernel_ulong_t swap_successes;
};


#endif /* _UAPI_LINUX_SHM_H_ */

Overall Contributors

PersonTokensPropCommitsCommitProp
David Howells19070.37%116.67%
Mike Kravetz6624.44%116.67%
H. J. Lu51.85%116.67%
Manfred Spraul51.85%116.67%
Davidlohr Bueso A31.11%116.67%
Greg Kroah-Hartman10.37%116.67%
Total270100.00%6100.00%
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