include/linux/shm.h

   1 #ifndef _LINUX_SHM_H_
   2 #define _LINUX_SHM_H_
   3
   4 #include <asm/page.h>
   5 #include <uapi/linux/shm.h>
   6
   7 #define SHMALL (SHMMAX/PAGE_SIZE*(SHMMNI/16)) /* max shm system wide (pages) */
   8 #include <asm/shmparam.h>
   9 struct shmid_kernel /* private to the kernel */
  10 {
  11         struct kern_ipc_perm    shm_perm;
  12         struct file *           shm_file;
  13         unsigned long           shm_nattch;
  14         unsigned long           shm_segsz;
  15         time_t                  shm_atim;
  16         time_t                  shm_dtim;
  17         time_t                  shm_ctim;
  18         pid_t                   shm_cprid;
  19         pid_t                   shm_lprid;
  20         struct user_struct      *mlock_user;
  21
  22         /* The task created the shm object.  NULL if the task is dead. */
  23         struct task_struct      *shm_creator;
  24 };
  25
  26 /* shm_mode upper byte flags */
  27 #define SHM_DEST        01000   /* segment will be destroyed on last detach */
  28 #define SHM_LOCKED      02000   /* segment will not be swapped */
  29 #define SHM_HUGETLB     04000   /* segment will use huge TLB pages */
  30 #define SHM_NORESERVE   010000  /* don't check for reservations */
  31
  32 /* Bits [26:31] are reserved */
  33
  34 /*
  35  * When SHM_HUGETLB is set bits [26:31] encode the log2 of the huge page size.
  36  * This gives us 6 bits, which is enough until someone invents 128 bit address
  37  * spaces.
  38  *
  39  * Assume these are all power of twos.
  40  * When 0 use the default page size.
  41  */
  42 #define SHM_HUGE_SHIFT  26
  43 #define SHM_HUGE_MASK   0x3f
  44 #define SHM_HUGE_2MB    (21 << SHM_HUGE_SHIFT)
  45 #define SHM_HUGE_1GB    (30 << SHM_HUGE_SHIFT)
  46
  47 #ifdef CONFIG_SYSVIPC
  48 long do_shmat(int shmid, char __user *shmaddr, int shmflg, unsigned long *addr,
  49               unsigned long shmlba);
  50 extern int is_file_shm_hugepages(struct file *file);
  51 extern void exit_shm(struct task_struct *task);
  52 #else
  53 static inline long do_shmat(int shmid, char __user *shmaddr,
  54                             int shmflg, unsigned long *addr,
  55                             unsigned long shmlba)
  56 {
  57         return -ENOSYS;
  58 }
  59 static inline int is_file_shm_hugepages(struct file *file)
  60 {
  61         return 0;
  62 }
  63 static inline void exit_shm(struct task_struct *task)
  64 {
  65 }
  66 #endif
  67
  68 #endif /* _LINUX_SHM_H_ */