include/linux/shm.h

/* */
   1 #ifndef _LINUX_SHM_H_
   2 #define _LINUX_SHM_H_
   3 #include <linux/ipc.h>
   4 
   5 struct shmid_ds {
   6         struct ipc_perm shm_perm;       /* operation perms */
   7         int     shm_segsz;              /* size of segment (bytes) */
   8         time_t  shm_atime;              /* last attach time */
   9         time_t  shm_dtime;              /* last detach time */
  10         time_t  shm_ctime;              /* last change time */
  11         unsigned short  shm_cpid;       /* pid of creator */
  12         unsigned short  shm_lpid;       /* pid of last operator */
  13         short   shm_nattch;             /* no. of current attaches */
  14         /* the following are private */
  15         unsigned short   shm_npages;    /* size of segment (pages) */
  16         unsigned long   *shm_pages;     /* array of ptrs to frames -> SHMMAX */ 
  17         struct shm_desc *attaches;      /* descriptors for attaches */
  18 };
  19 
  20 /* mode for attach */
  21 #define SHM_RDONLY      010000  /* read-only access */
  22 #define SHM_RND         020000  /* round attach address to SHMLBA boundary */
  23 #define SHM_REMAP       040000  /* take-over region on attach */
  24 
  25 /* super user shmctl commands */
  26 #define SHM_LOCK        11
  27 #define SHM_UNLOCK      12
  28 
  29 struct  shminfo {
  30     int shmmax; 
  31     int shmmin; 
  32     int shmmni; 
  33     int shmseg; 
  34     int shmall; 
  35 };
  36 
  37 /* address range for shared memory attaches if no address passed to shmat() */
  38 #define SHM_RANGE_START 0x40000000
  39 #define SHM_RANGE_END   0x60000000
  40 
  41 /* format of page table entries that correspond to shared memory pages
  42    currently out in swap space (see also mm/swap.c):
  43    bit 0 (PAGE_PRESENT) is  = 0
  44    bits 7..1 (SWP_TYPE) are = SHM_SWP_TYPE
  45    bits 31..8 are used like this:
  46    bits 14..8 (SHM_ID) the id of the shared memory segment
  47    bits 29..15 (SHM_IDX) the index of the page within the shared memory segment
  48                     (actually only bits 24..15 get used since SHMMAX is so low)
  49    bit 31 (SHM_READ_ONLY) flag whether the page belongs to a read-only attach
  50 */
  51 
  52 #define SHM_ID_SHIFT    8
  53 /* Keep _SHM_ID_BITS as low as possible since SHMMNI depends on it and
  54    there is a static array of size SHMMNI. */
  55 #define _SHM_ID_BITS    7
  56 #define SHM_ID_MASK     ((1<<_SHM_ID_BITS)-1)
  57 
  58 #define SHM_IDX_SHIFT   (SHM_ID_SHIFT+_SHM_ID_BITS)
  59 #define _SHM_IDX_BITS   15
  60 #define SHM_IDX_MASK    ((1<<_SHM_IDX_BITS)-1)
  61 
  62 #define SHM_READ_ONLY   (1<<31)
  63 
  64 /* We must have SHM_ID_SHIFT + _SHM_ID_BITS + _SHM_IDX_BITS + 1 <= 32
  65    and SHMMAX <= (PAGE_SIZE << _SHM_IDX_BITS). */
  66 
  67 #define SHMMAX 0x3fa000                         /* max shared seg size (bytes) */
  68 #define SHMMIN 1         /* really PAGE_SIZE */ /* min shared seg size (bytes) */
  69 #define SHMMNI (1<<_SHM_ID_BITS)                /* max num of segs system wide */
  70 #define SHMALL (1<<(_SHM_IDX_BITS+_SHM_ID_BITS))/* max shm system wide (pages) */
  71 #define SHMLBA 0x1000                           /* attach addr a multiple of this */
  72 #define SHMSEG SHMMNI                           /* max shared segs per process */
  73 
  74 #ifdef __KERNEL__
  75 
  76 /* shm_mode upper byte flags */
  77 #define SHM_DEST        01000   /* segment will be destroyed on last detach */
  78 #define SHM_LOCKED      02000   /* segment will not be swapped */
  79 
  80 /* ipcs ctl commands */
  81 #define SHM_STAT        13
  82 #define SHM_INFO        14
  83 struct shm_info {
  84         int   used_ids;
  85         ulong shm_tot; /* total allocated shm */
  86         ulong shm_rss; /* total resident shm */
  87         ulong shm_swp; /* total swapped shm */
  88         ulong swap_attempts;
  89         ulong swap_successes;
  90 };
  91 
  92 
  93 /*
  94  * Per process internal structure for managing segments.
  95  * A shmat will add to and shmdt will remove from the list.
  96  */
  97 struct  shm_desc {
  98         struct task_struct *task;     /* attacher */
  99         unsigned long shm_sgn;        /* signature for this attach */
 100         unsigned long start;   /* virt addr of attach, multiple of SHMLBA */
 101         unsigned long end;            /* multiple of SHMLBA */
 102         struct shm_desc *task_next;   /* next attach for task */
 103         struct shm_desc *seg_next;    /* next attach for segment */
 104 };
 105 
 106 #endif /* __KERNEL__ */
 107 
 108 #endif /* _LINUX_SHM_H_ */
 109
/* */
root/include/linux/shm.h

INCLUDED FROM
