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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 | |
181 | static inline void exit_robust_list(struct task_struct *curr) | |
182 | { | |
183 | } | |
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 |