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Linus Torvalds1da177e2005-04-16 15:20:36 -07001#ifndef _LINUX_FUTEX_H
2#define _LINUX_FUTEX_H
3
Ingo Molnar0771dfe2006-03-27 01:16:22 -08004#include <linux/sched.h>
5
Pierre Peifferc19384b2007-05-09 02:35:02 -07006union ktime;
7
Linus Torvalds1da177e2005-04-16 15:20:36 -07008/* Second argument to futex syscall */
9
10
Jakub Jelinek4732efb2005-09-06 15:16:25 -070011#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
Ingo Molnarc87e2832006-06-27 02:54:58 -070017#define FUTEX_LOCK_PI 6
18#define FUTEX_UNLOCK_PI 7
19#define FUTEX_TRYLOCK_PI 8
Linus Torvalds1da177e2005-04-16 15:20:36 -070020
Eric Dumazet34f01cc2007-05-09 02:35:04 -070021#define FUTEX_PRIVATE_FLAG 128
22#define FUTEX_CMD_MASK ~FUTEX_PRIVATE_FLAG
23
24#define FUTEX_WAIT_PRIVATE (FUTEX_WAIT | FUTEX_PRIVATE_FLAG)
25#define FUTEX_WAKE_PRIVATE (FUTEX_WAKE | FUTEX_PRIVATE_FLAG)
26#define FUTEX_REQUEUE_PRIVATE (FUTEX_REQUEUE | FUTEX_PRIVATE_FLAG)
27#define FUTEX_CMP_REQUEUE_PRIVATE (FUTEX_CMP_REQUEUE | FUTEX_PRIVATE_FLAG)
28#define FUTEX_WAKE_OP_PRIVATE (FUTEX_WAKE_OP | FUTEX_PRIVATE_FLAG)
29#define FUTEX_LOCK_PI_PRIVATE (FUTEX_LOCK_PI | FUTEX_PRIVATE_FLAG)
30#define FUTEX_UNLOCK_PI_PRIVATE (FUTEX_UNLOCK_PI | FUTEX_PRIVATE_FLAG)
31#define FUTEX_TRYLOCK_PI_PRIVATE (FUTEX_TRYLOCK_PI | FUTEX_PRIVATE_FLAG)
32
Ingo Molnar0771dfe2006-03-27 01:16:22 -080033/*
34 * Support for robust futexes: the kernel cleans up held futexes at
35 * thread exit time.
36 */
37
38/*
39 * Per-lock list entry - embedded in user-space locks, somewhere close
40 * to the futex field. (Note: user-space uses a double-linked list to
41 * achieve O(1) list add and remove, but the kernel only needs to know
42 * about the forward link)
43 *
44 * NOTE: this structure is part of the syscall ABI, and must not be
45 * changed.
46 */
47struct robust_list {
48 struct robust_list __user *next;
49};
50
51/*
52 * Per-thread list head:
53 *
54 * NOTE: this structure is part of the syscall ABI, and must only be
55 * changed if the change is first communicated with the glibc folks.
56 * (When an incompatible change is done, we'll increase the structure
57 * size, which glibc will detect)
58 */
59struct robust_list_head {
60 /*
61 * The head of the list. Points back to itself if empty:
62 */
63 struct robust_list list;
64
65 /*
66 * This relative offset is set by user-space, it gives the kernel
67 * the relative position of the futex field to examine. This way
68 * we keep userspace flexible, to freely shape its data-structure,
69 * without hardcoding any particular offset into the kernel:
70 */
71 long futex_offset;
72
73 /*
74 * The death of the thread may race with userspace setting
75 * up a lock's links. So to handle this race, userspace first
76 * sets this field to the address of the to-be-taken lock,
77 * then does the lock acquire, and then adds itself to the
78 * list, and then clears this field. Hence the kernel will
79 * always have full knowledge of all locks that the thread
80 * _might_ have taken. We check the owner TID in any case,
81 * so only truly owned locks will be handled.
82 */
83 struct robust_list __user *list_op_pending;
84};
85
86/*
87 * Are there any waiters for this robust futex:
88 */
89#define FUTEX_WAITERS 0x80000000
90
91/*
92 * The kernel signals via this bit that a thread holding a futex
93 * has exited without unlocking the futex. The kernel also does
94 * a FUTEX_WAKE on such futexes, after setting the bit, to wake
95 * up any possible waiters:
96 */
97#define FUTEX_OWNER_DIED 0x40000000
98
99/*
Ingo Molnar0771dfe2006-03-27 01:16:22 -0800100 * The rest of the robust-futex field is for the TID:
101 */
Thomas Gleixnerbd197232007-06-17 21:11:10 +0200102#define FUTEX_TID_MASK 0x3fffffff
Ingo Molnar0771dfe2006-03-27 01:16:22 -0800103
104/*
Ingo Molnar76b81e22006-03-27 01:16:28 -0800105 * This limit protects against a deliberately circular list.
106 * (Not worth introducing an rlimit for it)
Ingo Molnar0771dfe2006-03-27 01:16:22 -0800107 */
Ingo Molnar76b81e22006-03-27 01:16:28 -0800108#define ROBUST_LIST_LIMIT 2048
Ingo Molnar0771dfe2006-03-27 01:16:22 -0800109
David Woodhouse58f64d82006-12-10 02:19:11 -0800110#ifdef __KERNEL__
Pierre Peifferc19384b2007-05-09 02:35:02 -0700111long do_futex(u32 __user *uaddr, int op, u32 val, union ktime *timeout,
Ingo Molnare2970f22006-06-27 02:54:47 -0700112 u32 __user *uaddr2, u32 val2, u32 val3);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700113
Ingo Molnare3f2dde2006-07-29 05:17:57 +0200114extern int
115handle_futex_death(u32 __user *uaddr, struct task_struct *curr, int pi);
Ingo Molnar0771dfe2006-03-27 01:16:22 -0800116
Rusty Russell9adef582007-05-08 00:26:42 -0700117/*
118 * Futexes are matched on equal values of this key.
119 * The key type depends on whether it's a shared or private mapping.
120 * Don't rearrange members without looking at hash_futex().
121 *
122 * offset is aligned to a multiple of sizeof(u32) (== 4) by definition.
Eric Dumazet34f01cc2007-05-09 02:35:04 -0700123 * We use the two low order bits of offset to tell what is the kind of key :
124 * 00 : Private process futex (PTHREAD_PROCESS_PRIVATE)
125 * (no reference on an inode or mm)
126 * 01 : Shared futex (PTHREAD_PROCESS_SHARED)
127 * mapped on a file (reference on the underlying inode)
128 * 10 : Shared futex (PTHREAD_PROCESS_SHARED)
129 * (but private mapping on an mm, and reference taken on it)
130*/
131
132#define FUT_OFF_INODE 1 /* We set bit 0 if key has a reference on inode */
133#define FUT_OFF_MMSHARED 2 /* We set bit 1 if key has a reference on mm */
134
Rusty Russell9adef582007-05-08 00:26:42 -0700135union futex_key {
136 struct {
137 unsigned long pgoff;
138 struct inode *inode;
139 int offset;
140 } shared;
141 struct {
142 unsigned long address;
143 struct mm_struct *mm;
144 int offset;
145 } private;
146 struct {
147 unsigned long word;
148 void *ptr;
149 int offset;
150 } both;
151};
Eric Dumazet34f01cc2007-05-09 02:35:04 -0700152int get_futex_key(u32 __user *uaddr, struct rw_semaphore *shared,
153 union futex_key *key);
Rusty Russell9adef582007-05-08 00:26:42 -0700154void get_futex_key_refs(union futex_key *key);
155void drop_futex_key_refs(union futex_key *key);
156
Ingo Molnar0771dfe2006-03-27 01:16:22 -0800157#ifdef CONFIG_FUTEX
158extern void exit_robust_list(struct task_struct *curr);
Ingo Molnarc87e2832006-06-27 02:54:58 -0700159extern void exit_pi_state_list(struct task_struct *curr);
Ingo Molnar0771dfe2006-03-27 01:16:22 -0800160#else
161static inline void exit_robust_list(struct task_struct *curr)
162{
163}
Ingo Molnarc87e2832006-06-27 02:54:58 -0700164static inline void exit_pi_state_list(struct task_struct *curr)
165{
166}
Ingo Molnar0771dfe2006-03-27 01:16:22 -0800167#endif
David Woodhouse58f64d82006-12-10 02:19:11 -0800168#endif /* __KERNEL__ */
Ingo Molnar0771dfe2006-03-27 01:16:22 -0800169
Jakub Jelinek4732efb2005-09-06 15:16:25 -0700170#define FUTEX_OP_SET 0 /* *(int *)UADDR2 = OPARG; */
171#define FUTEX_OP_ADD 1 /* *(int *)UADDR2 += OPARG; */
172#define FUTEX_OP_OR 2 /* *(int *)UADDR2 |= OPARG; */
173#define FUTEX_OP_ANDN 3 /* *(int *)UADDR2 &= ~OPARG; */
174#define FUTEX_OP_XOR 4 /* *(int *)UADDR2 ^= OPARG; */
175
176#define FUTEX_OP_OPARG_SHIFT 8 /* Use (1 << OPARG) instead of OPARG. */
177
178#define FUTEX_OP_CMP_EQ 0 /* if (oldval == CMPARG) wake */
179#define FUTEX_OP_CMP_NE 1 /* if (oldval != CMPARG) wake */
180#define FUTEX_OP_CMP_LT 2 /* if (oldval < CMPARG) wake */
181#define FUTEX_OP_CMP_LE 3 /* if (oldval <= CMPARG) wake */
182#define FUTEX_OP_CMP_GT 4 /* if (oldval > CMPARG) wake */
183#define FUTEX_OP_CMP_GE 5 /* if (oldval >= CMPARG) wake */
184
185/* FUTEX_WAKE_OP will perform atomically
186 int oldval = *(int *)UADDR2;
187 *(int *)UADDR2 = oldval OP OPARG;
188 if (oldval CMP CMPARG)
189 wake UADDR2; */
190
191#define FUTEX_OP(op, oparg, cmp, cmparg) \
192 (((op & 0xf) << 28) | ((cmp & 0xf) << 24) \
193 | ((oparg & 0xfff) << 12) | (cmparg & 0xfff))
194
Linus Torvalds1da177e2005-04-16 15:20:36 -0700195#endif