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6f52b16c | 1 | /* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */ |
607ca46e DH |
2 | #ifndef _UAPI_LINUX_FUTEX_H |
3 | #define _UAPI_LINUX_FUTEX_H | |
4 | ||
5 | #include <linux/compiler.h> | |
6 | #include <linux/types.h> | |
7 | ||
8 | /* Second argument to futex syscall */ | |
9 | ||
10 | ||
11 | #define FUTEX_WAIT 0 | |
12 | #define FUTEX_WAKE 1 | |
13 | #define FUTEX_FD 2 | |
14 | #define FUTEX_REQUEUE 3 | |
15 | #define FUTEX_CMP_REQUEUE 4 | |
16 | #define FUTEX_WAKE_OP 5 | |
17 | #define FUTEX_LOCK_PI 6 | |
18 | #define FUTEX_UNLOCK_PI 7 | |
19 | #define FUTEX_TRYLOCK_PI 8 | |
20 | #define FUTEX_WAIT_BITSET 9 | |
21 | #define FUTEX_WAKE_BITSET 10 | |
22 | #define FUTEX_WAIT_REQUEUE_PI 11 | |
23 | #define FUTEX_CMP_REQUEUE_PI 12 | |
24 | ||
25 | #define FUTEX_PRIVATE_FLAG 128 | |
26 | #define FUTEX_CLOCK_REALTIME 256 | |
27 | #define FUTEX_CMD_MASK ~(FUTEX_PRIVATE_FLAG | FUTEX_CLOCK_REALTIME) | |
28 | ||
29 | #define FUTEX_WAIT_PRIVATE (FUTEX_WAIT | FUTEX_PRIVATE_FLAG) | |
30 | #define FUTEX_WAKE_PRIVATE (FUTEX_WAKE | FUTEX_PRIVATE_FLAG) | |
31 | #define FUTEX_REQUEUE_PRIVATE (FUTEX_REQUEUE | FUTEX_PRIVATE_FLAG) | |
32 | #define FUTEX_CMP_REQUEUE_PRIVATE (FUTEX_CMP_REQUEUE | FUTEX_PRIVATE_FLAG) | |
33 | #define FUTEX_WAKE_OP_PRIVATE (FUTEX_WAKE_OP | FUTEX_PRIVATE_FLAG) | |
34 | #define FUTEX_LOCK_PI_PRIVATE (FUTEX_LOCK_PI | FUTEX_PRIVATE_FLAG) | |
35 | #define FUTEX_UNLOCK_PI_PRIVATE (FUTEX_UNLOCK_PI | FUTEX_PRIVATE_FLAG) | |
36 | #define FUTEX_TRYLOCK_PI_PRIVATE (FUTEX_TRYLOCK_PI | FUTEX_PRIVATE_FLAG) | |
37 | #define FUTEX_WAIT_BITSET_PRIVATE (FUTEX_WAIT_BITSET | FUTEX_PRIVATE_FLAG) | |
38 | #define FUTEX_WAKE_BITSET_PRIVATE (FUTEX_WAKE_BITSET | FUTEX_PRIVATE_FLAG) | |
39 | #define FUTEX_WAIT_REQUEUE_PI_PRIVATE (FUTEX_WAIT_REQUEUE_PI | \ | |
40 | FUTEX_PRIVATE_FLAG) | |
41 | #define FUTEX_CMP_REQUEUE_PI_PRIVATE (FUTEX_CMP_REQUEUE_PI | \ | |
42 | FUTEX_PRIVATE_FLAG) | |
43 | ||
44 | /* | |
45 | * Support for robust futexes: the kernel cleans up held futexes at | |
46 | * thread exit time. | |
47 | */ | |
48 | ||
49 | /* | |
50 | * Per-lock list entry - embedded in user-space locks, somewhere close | |
51 | * to the futex field. (Note: user-space uses a double-linked list to | |
52 | * achieve O(1) list add and remove, but the kernel only needs to know | |
53 | * about the forward link) | |
54 | * | |
55 | * NOTE: this structure is part of the syscall ABI, and must not be | |
56 | * changed. | |
57 | */ | |
58 | struct robust_list { | |
59 | struct robust_list __user *next; | |
60 | }; | |
61 | ||
62 | /* | |
63 | * Per-thread list head: | |
64 | * | |
65 | * NOTE: this structure is part of the syscall ABI, and must only be | |
66 | * changed if the change is first communicated with the glibc folks. | |
67 | * (When an incompatible change is done, we'll increase the structure | |
68 | * size, which glibc will detect) | |
69 | */ | |
70 | struct robust_list_head { | |
71 | /* | |
72 | * The head of the list. Points back to itself if empty: | |
73 | */ | |
74 | struct robust_list list; | |
75 | ||
76 | /* | |
77 | * This relative offset is set by user-space, it gives the kernel | |
78 | * the relative position of the futex field to examine. This way | |
79 | * we keep userspace flexible, to freely shape its data-structure, | |
80 | * without hardcoding any particular offset into the kernel: | |
81 | */ | |
82 | long futex_offset; | |
83 | ||
84 | /* | |
85 | * The death of the thread may race with userspace setting | |
86 | * up a lock's links. So to handle this race, userspace first | |
87 | * sets this field to the address of the to-be-taken lock, | |
88 | * then does the lock acquire, and then adds itself to the | |
89 | * list, and then clears this field. Hence the kernel will | |
90 | * always have full knowledge of all locks that the thread | |
91 | * _might_ have taken. We check the owner TID in any case, | |
92 | * so only truly owned locks will be handled. | |
93 | */ | |
94 | struct robust_list __user *list_op_pending; | |
95 | }; | |
96 | ||
97 | /* | |
98 | * Are there any waiters for this robust futex: | |
99 | */ | |
100 | #define FUTEX_WAITERS 0x80000000 | |
101 | ||
102 | /* | |
103 | * The kernel signals via this bit that a thread holding a futex | |
104 | * has exited without unlocking the futex. The kernel also does | |
105 | * a FUTEX_WAKE on such futexes, after setting the bit, to wake | |
106 | * up any possible waiters: | |
107 | */ | |
108 | #define FUTEX_OWNER_DIED 0x40000000 | |
109 | ||
110 | /* | |
111 | * The rest of the robust-futex field is for the TID: | |
112 | */ | |
113 | #define FUTEX_TID_MASK 0x3fffffff | |
114 | ||
115 | /* | |
116 | * This limit protects against a deliberately circular list. | |
117 | * (Not worth introducing an rlimit for it) | |
118 | */ | |
119 | #define ROBUST_LIST_LIMIT 2048 | |
120 | ||
121 | /* | |
122 | * bitset with all bits set for the FUTEX_xxx_BITSET OPs to request a | |
123 | * match of any bit. | |
124 | */ | |
125 | #define FUTEX_BITSET_MATCH_ANY 0xffffffff | |
126 | ||
127 | ||
128 | #define FUTEX_OP_SET 0 /* *(int *)UADDR2 = OPARG; */ | |
129 | #define FUTEX_OP_ADD 1 /* *(int *)UADDR2 += OPARG; */ | |
130 | #define FUTEX_OP_OR 2 /* *(int *)UADDR2 |= OPARG; */ | |
131 | #define FUTEX_OP_ANDN 3 /* *(int *)UADDR2 &= ~OPARG; */ | |
132 | #define FUTEX_OP_XOR 4 /* *(int *)UADDR2 ^= OPARG; */ | |
133 | ||
134 | #define FUTEX_OP_OPARG_SHIFT 8 /* Use (1 << OPARG) instead of OPARG. */ | |
135 | ||
136 | #define FUTEX_OP_CMP_EQ 0 /* if (oldval == CMPARG) wake */ | |
137 | #define FUTEX_OP_CMP_NE 1 /* if (oldval != CMPARG) wake */ | |
138 | #define FUTEX_OP_CMP_LT 2 /* if (oldval < CMPARG) wake */ | |
139 | #define FUTEX_OP_CMP_LE 3 /* if (oldval <= CMPARG) wake */ | |
140 | #define FUTEX_OP_CMP_GT 4 /* if (oldval > CMPARG) wake */ | |
141 | #define FUTEX_OP_CMP_GE 5 /* if (oldval >= CMPARG) wake */ | |
142 | ||
143 | /* FUTEX_WAKE_OP will perform atomically | |
144 | int oldval = *(int *)UADDR2; | |
145 | *(int *)UADDR2 = oldval OP OPARG; | |
146 | if (oldval CMP CMPARG) | |
147 | wake UADDR2; */ | |
148 | ||
149 | #define FUTEX_OP(op, oparg, cmp, cmparg) \ | |
150 | (((op & 0xf) << 28) | ((cmp & 0xf) << 24) \ | |
151 | | ((oparg & 0xfff) << 12) | (cmparg & 0xfff)) | |
152 | ||
153 | #endif /* _UAPI_LINUX_FUTEX_H */ |