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1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 | #ifndef _LINUX_SHM_H_
#define _LINUX_SHM_H_
#include <linux/ipc.h>
struct shmid_ds {
struct ipc_perm shm_perm; /* operation perms */
int shm_segsz; /* size of segment (bytes) */
time_t shm_atime; /* last attach time */
time_t shm_dtime; /* last detach time */
time_t shm_ctime; /* last change time */
unsigned short shm_cpid; /* pid of creator */
unsigned short shm_lpid; /* pid of last operator */
short shm_nattch; /* no. of current attaches */
/* the following are private */
unsigned short shm_npages; /* size of segment (pages) */
unsigned long *shm_pages; /* array of ptrs to frames -> SHMMAX */
struct shm_desc *attaches; /* descriptors for attaches */
};
/* mode for attach */
#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 */
/* super user shmctl commands */
#define SHM_LOCK 11
#define SHM_UNLOCK 12
struct shminfo {
int shmmax;
int shmmin;
int shmmni;
int shmseg;
int shmall;
};
#define SHM_RANGE_START 0x40000000
#define SHM_RANGE_END 0x60000000
/* _SHM_ID_BITS is a variable you can adjust to */
/* tune the kernel. It determines the value of */
/* SHMMNI, which specifies the maximum no. of */
/* shared segments (system wide). SRB. */
#define _SHM_ID_BITS 7 /* keep as low as possible */
/* a static array is declared */
/* using SHMMNI */
#define __SHM_IDX_BITS (BITS_PER_PTR-2-SHM_IDX_SHIFT)
/* !!!!!!!?????
* Why reserve the two (2) high bits of the signature (shm_sgn) field?
* Since, as far as I can see, only the high bit is used (SHM_READ_ONLY).
* SRB.
*/
#define _SHM_IDX_BITS (__SHM_IDX_BITS+PAGE_SHIFT>=BITS_PER_PTR?\
BITS_PER_PTR-PAGE_SHIFT-1:__SHM_IDX_BITS) /* sanity check */
/* not present page table entry format bit 0 is 0, low byte defined in mm.h */
#define SHM_ID_SHIFT 8
#define SHM_ID_MASK ((1<<_SHM_ID_BITS)-1)
#define SHM_IDX_SHIFT (SHM_ID_SHIFT+_SHM_ID_BITS)
#define SHM_IDX_MASK ((1<<_SHM_IDX_BITS)-1)
#define SHM_READ_ONLY (1<<(BITS_PER_PTR-1))
#define SHMMAX 0x3fa000 /* max shared seg size (bytes) */
#define SHMMIN 1 /* really PAGE_SIZE */ /* min shared seg size (bytes) */
#define SHMMNI (1<<_SHM_ID_BITS) /* max num of segs system wide */
#define SHMALL (1<<(_SHM_IDX_BITS+_SHM_ID_BITS))/* max shm system wide (pages) */
#define SHMLBA 0x1000 /* attach addr a multiple of this */
#define SHMSEG SHMMNI /* max shared segs per process */
#ifdef __KERNEL__
/* shm_mode upper byte flags */
#define SHM_DEST 01000 /* segment will be destroyed on last detach */
#define SHM_LOCKED 02000 /* segment will not be swapped */
/* ipcs ctl commands */
#define SHM_STAT 13
#define SHM_INFO 14
struct shm_info {
int used_ids;
ulong shm_tot; /* total allocated shm */
ulong shm_rss; /* total resident shm */
ulong shm_swp; /* total swapped shm */
ulong swap_attempts;
ulong swap_successes;
};
/*
* Per process internal structure for managing segments.
* A shmat will add to and shmdt will remove from the list.
*/
struct shm_desc {
struct task_struct *task; /* attacher */
unsigned long shm_sgn; /* signature for this attach */
unsigned long start; /* virt addr of attach, multiple of SHMLBA */
unsigned long end; /* multiple of SHMLBA */
struct shm_desc *task_next; /* next attach for task */
struct shm_desc *seg_next; /* next attach for segment */
};
#endif /* __KERNEL__ */
#endif /* _LINUX_SHM_H_ */
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