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af8cc960 PZ |
1 | /* SPDX-License-Identifier: GPL-2.0 */ |
2 | #ifndef _FUTEX_H | |
3 | #define _FUTEX_H | |
4 | ||
85dc28fa | 5 | #include <linux/futex.h> |
807ff7ed | 6 | #include <linux/rtmutex.h> |
e5c68284 PZ |
7 | #include <linux/sched/wake_q.h> |
8 | ||
4d381673 PZ |
9 | #ifdef CONFIG_PREEMPT_RT |
10 | #include <linux/rcuwait.h> | |
11 | #endif | |
12 | ||
af8cc960 PZ |
13 | #include <asm/futex.h> |
14 | ||
15 | /* | |
16 | * Futex flags used to encode options to functions and preserve them across | |
17 | * restarts. | |
18 | */ | |
19 | #ifdef CONFIG_MMU | |
20 | # define FLAGS_SHARED 0x01 | |
21 | #else | |
22 | /* | |
23 | * NOMMU does not have per process address space. Let the compiler optimize | |
24 | * code away. | |
25 | */ | |
26 | # define FLAGS_SHARED 0x00 | |
27 | #endif | |
28 | #define FLAGS_CLOCKRT 0x02 | |
29 | #define FLAGS_HAS_TIMEOUT 0x04 | |
30 | ||
af8cc960 PZ |
31 | #ifdef CONFIG_FAIL_FUTEX |
32 | extern bool should_fail_futex(bool fshared); | |
33 | #else | |
34 | static inline bool should_fail_futex(bool fshared) | |
35 | { | |
36 | return false; | |
37 | } | |
38 | #endif | |
39 | ||
85dc28fa PZ |
40 | /* |
41 | * Hash buckets are shared by all the futex_keys that hash to the same | |
42 | * location. Each key may have multiple futex_q structures, one for each task | |
43 | * waiting on a futex. | |
44 | */ | |
45 | struct futex_hash_bucket { | |
46 | atomic_t waiters; | |
47 | spinlock_t lock; | |
48 | struct plist_head chain; | |
49 | } ____cacheline_aligned_in_smp; | |
50 | ||
51 | /* | |
52 | * Priority Inheritance state: | |
53 | */ | |
54 | struct futex_pi_state { | |
55 | /* | |
56 | * list of 'owned' pi_state instances - these have to be | |
57 | * cleaned up in do_exit() if the task exits prematurely: | |
58 | */ | |
59 | struct list_head list; | |
60 | ||
61 | /* | |
62 | * The PI object: | |
63 | */ | |
64 | struct rt_mutex_base pi_mutex; | |
65 | ||
66 | struct task_struct *owner; | |
67 | refcount_t refcount; | |
68 | ||
69 | union futex_key key; | |
70 | } __randomize_layout; | |
71 | ||
72 | /** | |
73 | * struct futex_q - The hashed futex queue entry, one per waiting task | |
74 | * @list: priority-sorted list of tasks waiting on this futex | |
75 | * @task: the task waiting on the futex | |
76 | * @lock_ptr: the hash bucket lock | |
77 | * @key: the key the futex is hashed on | |
78 | * @pi_state: optional priority inheritance state | |
79 | * @rt_waiter: rt_waiter storage for use with requeue_pi | |
80 | * @requeue_pi_key: the requeue_pi target futex key | |
81 | * @bitset: bitset for the optional bitmasked wakeup | |
82 | * @requeue_state: State field for futex_requeue_pi() | |
83 | * @requeue_wait: RCU wait for futex_requeue_pi() (RT only) | |
84 | * | |
85 | * We use this hashed waitqueue, instead of a normal wait_queue_entry_t, so | |
86 | * we can wake only the relevant ones (hashed queues may be shared). | |
87 | * | |
88 | * A futex_q has a woken state, just like tasks have TASK_RUNNING. | |
89 | * It is considered woken when plist_node_empty(&q->list) || q->lock_ptr == 0. | |
90 | * The order of wakeup is always to make the first condition true, then | |
91 | * the second. | |
92 | * | |
93 | * PI futexes are typically woken before they are removed from the hash list via | |
94 | * the rt_mutex code. See futex_unqueue_pi(). | |
95 | */ | |
96 | struct futex_q { | |
97 | struct plist_node list; | |
98 | ||
99 | struct task_struct *task; | |
100 | spinlock_t *lock_ptr; | |
101 | union futex_key key; | |
102 | struct futex_pi_state *pi_state; | |
103 | struct rt_mutex_waiter *rt_waiter; | |
104 | union futex_key *requeue_pi_key; | |
105 | u32 bitset; | |
106 | atomic_t requeue_state; | |
107 | #ifdef CONFIG_PREEMPT_RT | |
108 | struct rcuwait requeue_wait; | |
109 | #endif | |
110 | } __randomize_layout; | |
111 | ||
112 | extern const struct futex_q futex_q_init; | |
113 | ||
114 | enum futex_access { | |
115 | FUTEX_READ, | |
116 | FUTEX_WRITE | |
117 | }; | |
118 | ||
119 | extern int get_futex_key(u32 __user *uaddr, bool fshared, union futex_key *key, | |
120 | enum futex_access rw); | |
121 | ||
85dc28fa PZ |
122 | extern struct hrtimer_sleeper * |
123 | futex_setup_timer(ktime_t *time, struct hrtimer_sleeper *timeout, | |
124 | int flags, u64 range_ns); | |
125 | ||
e5c68284 PZ |
126 | extern struct futex_hash_bucket *futex_hash(union futex_key *key); |
127 | ||
128 | /** | |
129 | * futex_match - Check whether two futex keys are equal | |
130 | * @key1: Pointer to key1 | |
131 | * @key2: Pointer to key2 | |
132 | * | |
133 | * Return 1 if two futex_keys are equal, 0 otherwise. | |
134 | */ | |
135 | static inline int futex_match(union futex_key *key1, union futex_key *key2) | |
136 | { | |
137 | return (key1 && key2 | |
138 | && key1->both.word == key2->both.word | |
139 | && key1->both.ptr == key2->both.ptr | |
140 | && key1->both.offset == key2->both.offset); | |
141 | } | |
142 | ||
143 | extern int futex_wait_setup(u32 __user *uaddr, u32 val, unsigned int flags, | |
144 | struct futex_q *q, struct futex_hash_bucket **hb); | |
145 | extern void futex_wait_queue(struct futex_hash_bucket *hb, struct futex_q *q, | |
146 | struct hrtimer_sleeper *timeout); | |
147 | extern void futex_wake_mark(struct wake_q_head *wake_q, struct futex_q *q); | |
148 | ||
85dc28fa PZ |
149 | extern int fault_in_user_writeable(u32 __user *uaddr); |
150 | extern int futex_cmpxchg_value_locked(u32 *curval, u32 __user *uaddr, u32 uval, u32 newval); | |
151 | extern int futex_get_value_locked(u32 *dest, u32 __user *from); | |
152 | extern struct futex_q *futex_top_waiter(struct futex_hash_bucket *hb, union futex_key *key); | |
153 | ||
e5c68284 | 154 | extern void __futex_unqueue(struct futex_q *q); |
85dc28fa | 155 | extern void __futex_queue(struct futex_q *q, struct futex_hash_bucket *hb); |
a046f1a0 PZ |
156 | extern int futex_unqueue(struct futex_q *q); |
157 | ||
158 | /** | |
159 | * futex_queue() - Enqueue the futex_q on the futex_hash_bucket | |
160 | * @q: The futex_q to enqueue | |
161 | * @hb: The destination hash bucket | |
162 | * | |
163 | * The hb->lock must be held by the caller, and is released here. A call to | |
164 | * futex_queue() is typically paired with exactly one call to futex_unqueue(). The | |
165 | * exceptions involve the PI related operations, which may use futex_unqueue_pi() | |
166 | * or nothing if the unqueue is done as part of the wake process and the unqueue | |
167 | * state is implicit in the state of woken task (see futex_wait_requeue_pi() for | |
168 | * an example). | |
169 | */ | |
170 | static inline void futex_queue(struct futex_q *q, struct futex_hash_bucket *hb) | |
171 | __releases(&hb->lock) | |
172 | { | |
173 | __futex_queue(q, hb); | |
174 | spin_unlock(&hb->lock); | |
175 | } | |
176 | ||
85dc28fa PZ |
177 | extern void futex_unqueue_pi(struct futex_q *q); |
178 | ||
179 | extern void wait_for_owner_exiting(int ret, struct task_struct *exiting); | |
180 | ||
e5c68284 PZ |
181 | /* |
182 | * Reflects a new waiter being added to the waitqueue. | |
183 | */ | |
184 | static inline void futex_hb_waiters_inc(struct futex_hash_bucket *hb) | |
185 | { | |
186 | #ifdef CONFIG_SMP | |
187 | atomic_inc(&hb->waiters); | |
188 | /* | |
189 | * Full barrier (A), see the ordering comment above. | |
190 | */ | |
191 | smp_mb__after_atomic(); | |
192 | #endif | |
193 | } | |
194 | ||
195 | /* | |
196 | * Reflects a waiter being removed from the waitqueue by wakeup | |
197 | * paths. | |
198 | */ | |
199 | static inline void futex_hb_waiters_dec(struct futex_hash_bucket *hb) | |
200 | { | |
201 | #ifdef CONFIG_SMP | |
202 | atomic_dec(&hb->waiters); | |
203 | #endif | |
204 | } | |
205 | ||
a046f1a0 PZ |
206 | static inline int futex_hb_waiters_pending(struct futex_hash_bucket *hb) |
207 | { | |
208 | #ifdef CONFIG_SMP | |
209 | /* | |
210 | * Full barrier (B), see the ordering comment above. | |
211 | */ | |
212 | smp_mb(); | |
213 | return atomic_read(&hb->waiters); | |
214 | #else | |
215 | return 1; | |
216 | #endif | |
217 | } | |
218 | ||
85dc28fa PZ |
219 | extern struct futex_hash_bucket *futex_q_lock(struct futex_q *q); |
220 | extern void futex_q_unlock(struct futex_hash_bucket *hb); | |
221 | ||
222 | ||
223 | extern int futex_lock_pi_atomic(u32 __user *uaddr, struct futex_hash_bucket *hb, | |
224 | union futex_key *key, | |
225 | struct futex_pi_state **ps, | |
226 | struct task_struct *task, | |
227 | struct task_struct **exiting, | |
228 | int set_waiters); | |
229 | ||
230 | extern int refill_pi_state_cache(void); | |
231 | extern void get_pi_state(struct futex_pi_state *pi_state); | |
232 | extern void put_pi_state(struct futex_pi_state *pi_state); | |
233 | extern int fixup_pi_owner(u32 __user *uaddr, struct futex_q *q, int locked); | |
234 | ||
e5c68284 PZ |
235 | /* |
236 | * Express the locking dependencies for lockdep: | |
237 | */ | |
238 | static inline void | |
239 | double_lock_hb(struct futex_hash_bucket *hb1, struct futex_hash_bucket *hb2) | |
240 | { | |
bff7c57c PZ |
241 | if (hb1 > hb2) |
242 | swap(hb1, hb2); | |
243 | ||
244 | spin_lock(&hb1->lock); | |
245 | if (hb1 != hb2) | |
246 | spin_lock_nested(&hb2->lock, SINGLE_DEPTH_NESTING); | |
e5c68284 PZ |
247 | } |
248 | ||
249 | static inline void | |
250 | double_unlock_hb(struct futex_hash_bucket *hb1, struct futex_hash_bucket *hb2) | |
251 | { | |
252 | spin_unlock(&hb1->lock); | |
253 | if (hb1 != hb2) | |
254 | spin_unlock(&hb2->lock); | |
255 | } | |
256 | ||
85dc28fa PZ |
257 | /* syscalls */ |
258 | ||
af8cc960 PZ |
259 | extern int futex_wait_requeue_pi(u32 __user *uaddr, unsigned int flags, u32 |
260 | val, ktime_t *abs_time, u32 bitset, u32 __user | |
261 | *uaddr2); | |
262 | ||
263 | extern int futex_requeue(u32 __user *uaddr1, unsigned int flags, | |
264 | u32 __user *uaddr2, int nr_wake, int nr_requeue, | |
265 | u32 *cmpval, int requeue_pi); | |
266 | ||
267 | extern int futex_wait(u32 __user *uaddr, unsigned int flags, u32 val, | |
268 | ktime_t *abs_time, u32 bitset); | |
269 | ||
bf69bad3 AA |
270 | /** |
271 | * struct futex_vector - Auxiliary struct for futex_waitv() | |
272 | * @w: Userspace provided data | |
273 | * @q: Kernel side data | |
274 | * | |
275 | * Struct used to build an array with all data need for futex_waitv() | |
276 | */ | |
277 | struct futex_vector { | |
278 | struct futex_waitv w; | |
279 | struct futex_q q; | |
280 | }; | |
281 | ||
282 | extern int futex_wait_multiple(struct futex_vector *vs, unsigned int count, | |
283 | struct hrtimer_sleeper *to); | |
284 | ||
af8cc960 PZ |
285 | extern int futex_wake(u32 __user *uaddr, unsigned int flags, int nr_wake, u32 bitset); |
286 | ||
287 | extern int futex_wake_op(u32 __user *uaddr1, unsigned int flags, | |
288 | u32 __user *uaddr2, int nr_wake, int nr_wake2, int op); | |
289 | ||
290 | extern int futex_unlock_pi(u32 __user *uaddr, unsigned int flags); | |
291 | ||
292 | extern int futex_lock_pi(u32 __user *uaddr, unsigned int flags, ktime_t *time, int trylock); | |
293 | ||
294 | #endif /* _FUTEX_H */ |