Line data    Source code

       1             : /* SPDX-License-Identifier: GPL-2.0 */
       2             : #ifndef _LINUX_FUTEX_H
       3             : #define _LINUX_FUTEX_H
       4             : 
       5             : #include <linux/sched.h>
       6             : #include <linux/ktime.h>
       7             : 
       8             : #include <uapi/linux/futex.h>
       9             : 
      10             : struct inode;
      11             : struct mm_struct;
      12             : struct task_struct;
      13             : 
      14             : /*
      15             :  * Futexes are matched on equal values of this key.
      16             :  * The key type depends on whether it's a shared or private mapping.
      17             :  * Don't rearrange members without looking at hash_futex().
      18             :  *
      19             :  * offset is aligned to a multiple of sizeof(u32) (== 4) by definition.
      20             :  * We use the two low order bits of offset to tell what is the kind of key :
      21             :  *  00 : Private process futex (PTHREAD_PROCESS_PRIVATE)
      22             :  *       (no reference on an inode or mm)
      23             :  *  01 : Shared futex (PTHREAD_PROCESS_SHARED)
      24             :  *      mapped on a file (reference on the underlying inode)
      25             :  *  10 : Shared futex (PTHREAD_PROCESS_SHARED)
      26             :  *       (but private mapping on an mm, and reference taken on it)
      27             : */
      28             : 
      29             : #define FUT_OFF_INODE    1 /* We set bit 0 if key has a reference on inode */
      30             : #define FUT_OFF_MMSHARED 2 /* We set bit 1 if key has a reference on mm */
      31             : 
      32             : union futex_key {
      33             :         struct {
      34             :                 u64 i_seq;
      35             :                 unsigned long pgoff;
      36             :                 unsigned int offset;
      37             :         } shared;
      38             :         struct {
      39             :                 union {
      40             :                         struct mm_struct *mm;
      41             :                         u64 __tmp;
      42             :                 };
      43             :                 unsigned long address;
      44             :                 unsigned int offset;
      45             :         } private;
      46             :         struct {
      47             :                 u64 ptr;
      48             :                 unsigned long word;
      49             :                 unsigned int offset;
      50             :         } both;
      51             : };
      52             : 
      53             : #define FUTEX_KEY_INIT (union futex_key) { .both = { .ptr = 0ULL } }
      54             : 
      55             : #ifdef CONFIG_FUTEX
      56             : enum {
      57             :         FUTEX_STATE_OK,
      58             :         FUTEX_STATE_EXITING,
      59             :         FUTEX_STATE_DEAD,
      60             : };
      61             : 
      62         916 : static inline void futex_init_task(struct task_struct *tsk)
      63             : {
      64         916 :         tsk->robust_list = NULL;
      65             : #ifdef CONFIG_COMPAT
      66         916 :         tsk->compat_robust_list = NULL;
      67             : #endif
      68         916 :         INIT_LIST_HEAD(&tsk->pi_state_list);
      69         916 :         tsk->pi_state_cache = NULL;
      70         916 :         tsk->futex_state = FUTEX_STATE_OK;
      71         916 :         mutex_init(&tsk->futex_exit_mutex);
      72         916 : }
      73             : 
      74             : void futex_exit_recursive(struct task_struct *tsk);
      75             : void futex_exit_release(struct task_struct *tsk);
      76             : void futex_exec_release(struct task_struct *tsk);
      77             : 
      78             : long do_futex(u32 __user *uaddr, int op, u32 val, ktime_t *timeout,
      79             :               u32 __user *uaddr2, u32 val2, u32 val3);
      80             : #else
      81             : static inline void futex_init_task(struct task_struct *tsk) { }
      82             : static inline void futex_exit_recursive(struct task_struct *tsk) { }
      83             : static inline void futex_exit_release(struct task_struct *tsk) { }
      84             : static inline void futex_exec_release(struct task_struct *tsk) { }
      85             : static inline long do_futex(u32 __user *uaddr, int op, u32 val,
      86             :                             ktime_t *timeout, u32 __user *uaddr2,
      87             :                             u32 val2, u32 val3)
      88             : {
      89             :         return -EINVAL;
      90             : }
      91             : #endif
      92             : 
      93             : #endif