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
10struct inode;
11struct mm_struct;
12struct 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
32union 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
56enum {
57	FUTEX_STATE_OK,
58	FUTEX_STATE_EXITING,
59	FUTEX_STATE_DEAD,
60};
61
62static 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
74void futex_exit_recursive(struct task_struct *tsk);
75void futex_exit_release(struct task_struct *tsk);
76void futex_exec_release(struct task_struct *tsk);
77
78long do_futex(u32 __user *uaddr, int op, u32 val, ktime_t *timeout,
79	      u32 __user *uaddr2, u32 val2, u32 val3);
80#else
81static inline void futex_init_task(struct task_struct *tsk) { }
82static inline void futex_exit_recursive(struct task_struct *tsk) { }
83static inline void futex_exit_release(struct task_struct *tsk) { }
84static inline void futex_exec_release(struct task_struct *tsk) { }
85static 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