linux/include/linux/shm.h
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   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>
   9struct 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
  48long do_shmat(int shmid, char __user *shmaddr, int shmflg, unsigned long *addr,
  49              unsigned long shmlba);
  50extern int is_file_shm_hugepages(struct file *file);
  51extern void exit_shm(struct task_struct *task);
  52#else
  53static inline long do_shmat(int shmid, char __user *shmaddr,
  54                            int shmflg, unsigned long *addr,
  55                            unsigned long shmlba)
  56{
  57        return -ENOSYS;
  58}
  59static inline int is_file_shm_hugepages(struct file *file)
  60{
  61        return 0;
  62}
  63static inline void exit_shm(struct task_struct *task)
  64{
  65}
  66#endif
  67
  68#endif /* _LINUX_SHM_H_ */
  69
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