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 
futex_init_task(struct task_struct * tsk)62 static inline void futex_init_task(struct task_struct *tsk)
63 {
64 	tsk->robust_list = NULL;
65 #ifdef CONFIG_COMPAT
66 	tsk->compat_robust_list = NULL;
67 #endif
68 	INIT_LIST_HEAD(&tsk->pi_state_list);
69 	tsk->pi_state_cache = NULL;
70 	tsk->futex_state = FUTEX_STATE_OK;
71 	mutex_init(&tsk->futex_exit_mutex);
72 }
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
futex_init_task(struct task_struct * tsk)81 static inline void futex_init_task(struct task_struct *tsk) { }
futex_exit_recursive(struct task_struct * tsk)82 static inline void futex_exit_recursive(struct task_struct *tsk) { }
futex_exit_release(struct task_struct * tsk)83 static inline void futex_exit_release(struct task_struct *tsk) { }
futex_exec_release(struct task_struct * tsk)84 static inline void futex_exec_release(struct task_struct *tsk) { }
do_futex(u32 __user * uaddr,int op,u32 val,ktime_t * timeout,u32 __user * uaddr2,u32 val2,u32 val3)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
94