include/linux/shm.h

   1 #ifndef _LINUX_SHM_H_
   2 #define _LINUX_SHM_H_
   3
   4 #include <linux/list.h>
   5 #include <asm/page.h>
   6 #include <uapi/linux/shm.h>
   7 #include <asm/shmparam.h>
   8
   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         struct list_head        shm_clist;      /* list by creator */
  25 } __randomize_layout;
  26
  27 /* shm_mode upper byte flags */
  28 #define SHM_DEST        01000   /* segment will be destroyed on last detach */
  29 #define SHM_LOCKED      02000   /* segment will not be swapped */
  30 #define SHM_HUGETLB     04000   /* segment will use huge TLB pages */
  31 #define SHM_NORESERVE   010000  /* don't check for reservations */
  32
  33 /* Bits [26:31] are reserved */
  34
  35 /*
  36  * When SHM_HUGETLB is set bits [26:31] encode the log2 of the huge page size.
  37  * This gives us 6 bits, which is enough until someone invents 128 bit address
  38  * spaces.
  39  *
  40  * Assume these are all power of twos.
  41  * When 0 use the default page size.
  42  */
  43 #define SHM_HUGE_SHIFT  26
  44 #define SHM_HUGE_MASK   0x3f
  45 #define SHM_HUGE_2MB    (21 << SHM_HUGE_SHIFT)
  46 #define SHM_HUGE_1GB    (30 << SHM_HUGE_SHIFT)
  47
  48 #ifdef CONFIG_SYSVIPC
  49 struct sysv_shm {
  50         struct list_head shm_clist;
  51 };
  52
  53 long do_shmat(int shmid, char __user *shmaddr, int shmflg, unsigned long *addr,
  54               unsigned long shmlba);
  55 bool is_file_shm_hugepages(struct file *file);
  56 void exit_shm(struct task_struct *task);
  57 #define shm_init_task(task) INIT_LIST_HEAD(&(task)->sysvshm.shm_clist)
  58 #else
  59 struct sysv_shm {
  60         /* empty */
  61 };
  62
  63 static inline long do_shmat(int shmid, char __user *shmaddr,
  64                             int shmflg, unsigned long *addr,
  65                             unsigned long shmlba)
  66 {
  67         return -ENOSYS;
  68 }
  69 static inline bool is_file_shm_hugepages(struct file *file)
  70 {
  71         return false;
  72 }
  73 static inline void exit_shm(struct task_struct *task)
  74 {
  75 }
  76 static inline void shm_init_task(struct task_struct *task)
  77 {
  78 }
  79 #endif
  80
  81 #endif /* _LINUX_SHM_H_ */