1 #ifndef _LINUX_FUTEX_H
2 #define _LINUX_FUTEX_H
3
4 #include <linux/sched.h>
5
6 /* Second argument to futex syscall */
7
8
9 #define FUTEX_WAIT 0
10 #define FUTEX_WAKE 1
11 #define FUTEX_FD 2
12 #define FUTEX_REQUEUE 3
13 #define FUTEX_CMP_REQUEUE 4
14 #define FUTEX_WAKE_OP 5
15 #define FUTEX_LOCK_PI 6
16 #define FUTEX_UNLOCK_PI 7
17 #define FUTEX_TRYLOCK_PI 8
18
19 /*
20 * Support for robust futexes: the kernel cleans up held futexes at
21 * thread exit time.
22 */
23
24 /*
25 * Per-lock list entry - embedded in user-space locks, somewhere close
26 * to the futex field. (Note: user-space uses a double-linked list to
27 * achieve O(1) list add and remove, but the kernel only needs to know
28 * about the forward link)
29 *
30 * NOTE: this structure is part of the syscall ABI, and must not be
31 * changed.
32 */
33 struct robust_list {
34 struct robust_list __user *next;
35 };
36
37 /*
38 * Per-thread list head:
39 *
40 * NOTE: this structure is part of the syscall ABI, and must only be
41 * changed if the change is first communicated with the glibc folks.
42 * (When an incompatible change is done, we'll increase the structure
43 * size, which glibc will detect)
44 */
45 struct robust_list_head {
46 /*
47 * The head of the list. Points back to itself if empty:
48 */
49 struct robust_list list;
50
51 /*
52 * This relative offset is set by user-space, it gives the kernel
53 * the relative position of the futex field to examine. This way
54 * we keep userspace flexible, to freely shape its data-structure,
55 * without hardcoding any particular offset into the kernel:
56 */
57 long futex_offset;
58
59 /*
60 * The death of the thread may race with userspace setting
61 * up a lock's links. So to handle this race, userspace first
62 * sets this field to the address of the to-be-taken lock,
63 * then does the lock acquire, and then adds itself to the
64 * list, and then clears this field. Hence the kernel will
65 * always have full knowledge of all locks that the thread
66 * _might_ have taken. We check the owner TID in any case,
67 * so only truly owned locks will be handled.
68 */
69 struct robust_list __user *list_op_pending;
70 };
71
72 /*
73 * Are there any waiters for this robust futex:
74 */
75 #define FUTEX_WAITERS 0x80000000
76
77 /*
78 * The kernel signals via this bit that a thread holding a futex
79 * has exited without unlocking the futex. The kernel also does
80 * a FUTEX_WAKE on such futexes, after setting the bit, to wake
81 * up any possible waiters:
82 */
83 #define FUTEX_OWNER_DIED 0x40000000
84
85 /*
86 * The rest of the robust-futex field is for the TID:
87 */
88 #define FUTEX_TID_MASK 0x3fffffff
89
90 /*
91 * This limit protects against a deliberately circular list.
92 * (Not worth introducing an rlimit for it)
93 */
94 #define ROBUST_LIST_LIMIT 2048
95
96 long do_futex(u32 __user *uaddr, int op, u32 val, unsigned long timeout,
97 u32 __user *uaddr2, u32 val2, u32 val3);
98
99 extern int
100 handle_futex_death(u32 __user *uaddr, struct task_struct *curr, int pi);
101
102 #ifdef CONFIG_FUTEX
103 extern void exit_robust_list(struct task_struct *curr);
104 extern void exit_pi_state_list(struct task_struct *curr);
105 #else
exit_robust_list(struct task_struct * curr)106 static inline void exit_robust_list(struct task_struct *curr)
107 {
108 }
exit_pi_state_list(struct task_struct * curr)109 static inline void exit_pi_state_list(struct task_struct *curr)
110 {
111 }
112 #endif
113
114 #define FUTEX_OP_SET 0 /* *(int *)UADDR2 = OPARG; */
115 #define FUTEX_OP_ADD 1 /* *(int *)UADDR2 += OPARG; */
116 #define FUTEX_OP_OR 2 /* *(int *)UADDR2 |= OPARG; */
117 #define FUTEX_OP_ANDN 3 /* *(int *)UADDR2 &= ~OPARG; */
118 #define FUTEX_OP_XOR 4 /* *(int *)UADDR2 ^= OPARG; */
119
120 #define FUTEX_OP_OPARG_SHIFT 8 /* Use (1 << OPARG) instead of OPARG. */
121
122 #define FUTEX_OP_CMP_EQ 0 /* if (oldval == CMPARG) wake */
123 #define FUTEX_OP_CMP_NE 1 /* if (oldval != CMPARG) wake */
124 #define FUTEX_OP_CMP_LT 2 /* if (oldval < CMPARG) wake */
125 #define FUTEX_OP_CMP_LE 3 /* if (oldval <= CMPARG) wake */
126 #define FUTEX_OP_CMP_GT 4 /* if (oldval > CMPARG) wake */
127 #define FUTEX_OP_CMP_GE 5 /* if (oldval >= CMPARG) wake */
128
129 /* FUTEX_WAKE_OP will perform atomically
130 int oldval = *(int *)UADDR2;
131 *(int *)UADDR2 = oldval OP OPARG;
132 if (oldval CMP CMPARG)
133 wake UADDR2; */
134
135 #define FUTEX_OP(op, oparg, cmp, cmparg) \
136 (((op & 0xf) << 28) | ((cmp & 0xf) << 24) \
137 | ((oparg & 0xfff) << 12) | (cmparg & 0xfff))
138
139 #endif
140