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 */
33struct 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 */
45struct 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
96long do_futex(u32 __user *uaddr, int op, u32 val, unsigned long timeout,
97	      u32 __user *uaddr2, u32 val2, u32 val3);
98
99extern int
100handle_futex_death(u32 __user *uaddr, struct task_struct *curr, int pi);
101
102#ifdef CONFIG_FUTEX
103extern void exit_robust_list(struct task_struct *curr);
104extern void exit_pi_state_list(struct task_struct *curr);
105#else
106static inline void exit_robust_list(struct task_struct *curr)
107{
108}
109static 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