1 #ifndef _LINUX_FUTEX_H
2 #define _LINUX_FUTEX_H
3
4 #include <linux/compiler.h>
5 #include <linux/types.h>
6
7 /* Second argument to futex syscall */
8
9
10 #define FUTEX_WAIT 0
11 #define FUTEX_WAKE 1
12 #define FUTEX_FD 2
13 #define FUTEX_REQUEUE 3
14 #define FUTEX_CMP_REQUEUE 4
15 #define FUTEX_WAKE_OP 5
16 #define FUTEX_LOCK_PI 6
17 #define FUTEX_UNLOCK_PI 7
18 #define FUTEX_TRYLOCK_PI 8
19 #define FUTEX_WAIT_BITSET 9
20 #define FUTEX_WAKE_BITSET 10
21 #define FUTEX_WAIT_REQUEUE_PI 11
22 #define FUTEX_CMP_REQUEUE_PI 12
23
24 #define FUTEX_PRIVATE_FLAG 128
25 #define FUTEX_CLOCK_REALTIME 256
26 #define FUTEX_CMD_MASK ~(FUTEX_PRIVATE_FLAG | FUTEX_CLOCK_REALTIME)
27
28 #define FUTEX_WAIT_PRIVATE (FUTEX_WAIT | FUTEX_PRIVATE_FLAG)
29 #define FUTEX_WAKE_PRIVATE (FUTEX_WAKE | FUTEX_PRIVATE_FLAG)
30 #define FUTEX_REQUEUE_PRIVATE (FUTEX_REQUEUE | FUTEX_PRIVATE_FLAG)
31 #define FUTEX_CMP_REQUEUE_PRIVATE (FUTEX_CMP_REQUEUE | FUTEX_PRIVATE_FLAG)
32 #define FUTEX_WAKE_OP_PRIVATE (FUTEX_WAKE_OP | FUTEX_PRIVATE_FLAG)
33 #define FUTEX_LOCK_PI_PRIVATE (FUTEX_LOCK_PI | FUTEX_PRIVATE_FLAG)
34 #define FUTEX_UNLOCK_PI_PRIVATE (FUTEX_UNLOCK_PI | FUTEX_PRIVATE_FLAG)
35 #define FUTEX_TRYLOCK_PI_PRIVATE (FUTEX_TRYLOCK_PI | FUTEX_PRIVATE_FLAG)
36 #define FUTEX_WAIT_BITSET_PRIVATE (FUTEX_WAIT_BITSET | FUTEX_PRIVATE_FLAG)
37 #define FUTEX_WAKE_BITSET_PRIVATE (FUTEX_WAKE_BITSET | FUTEX_PRIVATE_FLAG)
38 #define FUTEX_WAIT_REQUEUE_PI_PRIVATE (FUTEX_WAIT_REQUEUE_PI | \
39 FUTEX_PRIVATE_FLAG)
40 #define FUTEX_CMP_REQUEUE_PI_PRIVATE (FUTEX_CMP_REQUEUE_PI | \
41 FUTEX_PRIVATE_FLAG)
42
43 /*
44 * Support for robust futexes: the kernel cleans up held futexes at
45 * thread exit time.
46 */
47
48 /*
49 * Per-lock list entry - embedded in user-space locks, somewhere close
50 * to the futex field. (Note: user-space uses a double-linked list to
51 * achieve O(1) list add and remove, but the kernel only needs to know
52 * about the forward link)
53 *
54 * NOTE: this structure is part of the syscall ABI, and must not be
55 * changed.
56 */
57 struct robust_list {
58 struct robust_list __user *next;
59 };
60
61 /*
62 * Per-thread list head:
63 *
64 * NOTE: this structure is part of the syscall ABI, and must only be
65 * changed if the change is first communicated with the glibc folks.
66 * (When an incompatible change is done, we'll increase the structure
67 * size, which glibc will detect)
68 */
69 struct robust_list_head {
70 /*
71 * The head of the list. Points back to itself if empty:
72 */
73 struct robust_list list;
74
75 /*
76 * This relative offset is set by user-space, it gives the kernel
77 * the relative position of the futex field to examine. This way
78 * we keep userspace flexible, to freely shape its data-structure,
79 * without hardcoding any particular offset into the kernel:
80 */
81 long futex_offset;
82
83 /*
84 * The death of the thread may race with userspace setting
85 * up a lock's links. So to handle this race, userspace first
86 * sets this field to the address of the to-be-taken lock,
87 * then does the lock acquire, and then adds itself to the
88 * list, and then clears this field. Hence the kernel will
89 * always have full knowledge of all locks that the thread
90 * _might_ have taken. We check the owner TID in any case,
91 * so only truly owned locks will be handled.
92 */
93 struct robust_list __user *list_op_pending;
94 };
95
96 /*
97 * Are there any waiters for this robust futex:
98 */
99 #define FUTEX_WAITERS 0x80000000
100
101 /*
102 * The kernel signals via this bit that a thread holding a futex
103 * has exited without unlocking the futex. The kernel also does
104 * a FUTEX_WAKE on such futexes, after setting the bit, to wake
105 * up any possible waiters:
106 */
107 #define FUTEX_OWNER_DIED 0x40000000
108
109 /*
110 * The rest of the robust-futex field is for the TID:
111 */
112 #define FUTEX_TID_MASK 0x3fffffff
113
114 /*
115 * This limit protects against a deliberately circular list.
116 * (Not worth introducing an rlimit for it)
117 */
118 #define ROBUST_LIST_LIMIT 2048
119
120 /*
121 * bitset with all bits set for the FUTEX_xxx_BITSET OPs to request a
122 * match of any bit.
123 */
124 #define FUTEX_BITSET_MATCH_ANY 0xffffffff
125
126 #ifdef __KERNEL__
127 struct inode;
128 struct mm_struct;
129 struct task_struct;
130 union ktime;
131
132 long do_futex(u32 __user *uaddr, int op, u32 val, union ktime *timeout,
133 u32 __user *uaddr2, u32 val2, u32 val3);
134
135 extern int
136 handle_futex_death(u32 __user *uaddr, struct task_struct *curr, int pi);
137
138 /*
139 * Futexes are matched on equal values of this key.
140 * The key type depends on whether it's a shared or private mapping.
141 * Don't rearrange members without looking at hash_futex().
142 *
143 * offset is aligned to a multiple of sizeof(u32) (== 4) by definition.
144 * We use the two low order bits of offset to tell what is the kind of key :
145 * 00 : Private process futex (PTHREAD_PROCESS_PRIVATE)
146 * (no reference on an inode or mm)
147 * 01 : Shared futex (PTHREAD_PROCESS_SHARED)
148 * mapped on a file (reference on the underlying inode)
149 * 10 : Shared futex (PTHREAD_PROCESS_SHARED)
150 * (but private mapping on an mm, and reference taken on it)
151 */
152
153 #define FUT_OFF_INODE 1 /* We set bit 0 if key has a reference on inode */
154 #define FUT_OFF_MMSHARED 2 /* We set bit 1 if key has a reference on mm */
155
156 union futex_key {
157 struct {
158 unsigned long pgoff;
159 struct inode *inode;
160 int offset;
161 } shared;
162 struct {
163 unsigned long address;
164 struct mm_struct *mm;
165 int offset;
166 } private;
167 struct {
168 unsigned long word;
169 void *ptr;
170 int offset;
171 } both;
172 };
173
174 #define FUTEX_KEY_INIT (union futex_key) { .both = { .ptr = NULL } }
175
176 #ifdef CONFIG_FUTEX
177 extern void exit_robust_list(struct task_struct *curr);
178 extern void exit_pi_state_list(struct task_struct *curr);
179 extern int futex_cmpxchg_enabled;
180 #else
exit_robust_list(struct task_struct * curr)181 static inline void exit_robust_list(struct task_struct *curr)
182 {
183 }
exit_pi_state_list(struct task_struct * curr)184 static inline void exit_pi_state_list(struct task_struct *curr)
185 {
186 }
187 #endif
188 #endif /* __KERNEL__ */
189
190 #define FUTEX_OP_SET 0 /* *(int *)UADDR2 = OPARG; */
191 #define FUTEX_OP_ADD 1 /* *(int *)UADDR2 += OPARG; */
192 #define FUTEX_OP_OR 2 /* *(int *)UADDR2 |= OPARG; */
193 #define FUTEX_OP_ANDN 3 /* *(int *)UADDR2 &= ~OPARG; */
194 #define FUTEX_OP_XOR 4 /* *(int *)UADDR2 ^= OPARG; */
195
196 #define FUTEX_OP_OPARG_SHIFT 8 /* Use (1 << OPARG) instead of OPARG. */
197
198 #define FUTEX_OP_CMP_EQ 0 /* if (oldval == CMPARG) wake */
199 #define FUTEX_OP_CMP_NE 1 /* if (oldval != CMPARG) wake */
200 #define FUTEX_OP_CMP_LT 2 /* if (oldval < CMPARG) wake */
201 #define FUTEX_OP_CMP_LE 3 /* if (oldval <= CMPARG) wake */
202 #define FUTEX_OP_CMP_GT 4 /* if (oldval > CMPARG) wake */
203 #define FUTEX_OP_CMP_GE 5 /* if (oldval >= CMPARG) wake */
204
205 /* FUTEX_WAKE_OP will perform atomically
206 int oldval = *(int *)UADDR2;
207 *(int *)UADDR2 = oldval OP OPARG;
208 if (oldval CMP CMPARG)
209 wake UADDR2; */
210
211 #define FUTEX_OP(op, oparg, cmp, cmparg) \
212 (((op & 0xf) << 28) | ((cmp & 0xf) << 24) \
213 | ((oparg & 0xfff) << 12) | (cmparg & 0xfff))
214
215 #endif
216