Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
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linux
1#ifndef _LINUX_FUTEX_H
2#define _LINUX_FUTEX_H
3
4#include <linux/compiler.h>
5#include <linux/types.h>
6
7struct inode;
8struct mm_struct;
9struct task_struct;
10union ktime;
11
12/* Second argument to futex syscall */
13
14
15#define FUTEX_WAIT 0
16#define FUTEX_WAKE 1
17#define FUTEX_FD 2
18#define FUTEX_REQUEUE 3
19#define FUTEX_CMP_REQUEUE 4
20#define FUTEX_WAKE_OP 5
21#define FUTEX_LOCK_PI 6
22#define FUTEX_UNLOCK_PI 7
23#define FUTEX_TRYLOCK_PI 8
24#define FUTEX_WAIT_BITSET 9
25#define FUTEX_WAKE_BITSET 10
26
27#define FUTEX_PRIVATE_FLAG 128
28#define FUTEX_CMD_MASK ~FUTEX_PRIVATE_FLAG
29
30#define FUTEX_WAIT_PRIVATE (FUTEX_WAIT | FUTEX_PRIVATE_FLAG)
31#define FUTEX_WAKE_PRIVATE (FUTEX_WAKE | FUTEX_PRIVATE_FLAG)
32#define FUTEX_REQUEUE_PRIVATE (FUTEX_REQUEUE | FUTEX_PRIVATE_FLAG)
33#define FUTEX_CMP_REQUEUE_PRIVATE (FUTEX_CMP_REQUEUE | FUTEX_PRIVATE_FLAG)
34#define FUTEX_WAKE_OP_PRIVATE (FUTEX_WAKE_OP | FUTEX_PRIVATE_FLAG)
35#define FUTEX_LOCK_PI_PRIVATE (FUTEX_LOCK_PI | FUTEX_PRIVATE_FLAG)
36#define FUTEX_UNLOCK_PI_PRIVATE (FUTEX_UNLOCK_PI | FUTEX_PRIVATE_FLAG)
37#define FUTEX_TRYLOCK_PI_PRIVATE (FUTEX_TRYLOCK_PI | FUTEX_PRIVATE_FLAG)
38#define FUTEX_WAIT_BITSET_PRIVATE (FUTEX_WAIT_BITS | FUTEX_PRIVATE_FLAG)
39#define FUTEX_WAKE_BITSET_PRIVATE (FUTEX_WAKE_BITS | FUTEX_PRIVATE_FLAG)
40
41/*
42 * Support for robust futexes: the kernel cleans up held futexes at
43 * thread exit time.
44 */
45
46/*
47 * Per-lock list entry - embedded in user-space locks, somewhere close
48 * to the futex field. (Note: user-space uses a double-linked list to
49 * achieve O(1) list add and remove, but the kernel only needs to know
50 * about the forward link)
51 *
52 * NOTE: this structure is part of the syscall ABI, and must not be
53 * changed.
54 */
55struct robust_list {
56 struct robust_list __user *next;
57};
58
59/*
60 * Per-thread list head:
61 *
62 * NOTE: this structure is part of the syscall ABI, and must only be
63 * changed if the change is first communicated with the glibc folks.
64 * (When an incompatible change is done, we'll increase the structure
65 * size, which glibc will detect)
66 */
67struct robust_list_head {
68 /*
69 * The head of the list. Points back to itself if empty:
70 */
71 struct robust_list list;
72
73 /*
74 * This relative offset is set by user-space, it gives the kernel
75 * the relative position of the futex field to examine. This way
76 * we keep userspace flexible, to freely shape its data-structure,
77 * without hardcoding any particular offset into the kernel:
78 */
79 long futex_offset;
80
81 /*
82 * The death of the thread may race with userspace setting
83 * up a lock's links. So to handle this race, userspace first
84 * sets this field to the address of the to-be-taken lock,
85 * then does the lock acquire, and then adds itself to the
86 * list, and then clears this field. Hence the kernel will
87 * always have full knowledge of all locks that the thread
88 * _might_ have taken. We check the owner TID in any case,
89 * so only truly owned locks will be handled.
90 */
91 struct robust_list __user *list_op_pending;
92};
93
94/*
95 * Are there any waiters for this robust futex:
96 */
97#define FUTEX_WAITERS 0x80000000
98
99/*
100 * The kernel signals via this bit that a thread holding a futex
101 * has exited without unlocking the futex. The kernel also does
102 * a FUTEX_WAKE on such futexes, after setting the bit, to wake
103 * up any possible waiters:
104 */
105#define FUTEX_OWNER_DIED 0x40000000
106
107/*
108 * The rest of the robust-futex field is for the TID:
109 */
110#define FUTEX_TID_MASK 0x3fffffff
111
112/*
113 * This limit protects against a deliberately circular list.
114 * (Not worth introducing an rlimit for it)
115 */
116#define ROBUST_LIST_LIMIT 2048
117
118/*
119 * bitset with all bits set for the FUTEX_xxx_BITSET OPs to request a
120 * match of any bit.
121 */
122#define FUTEX_BITSET_MATCH_ANY 0xffffffff
123
124#ifdef __KERNEL__
125long do_futex(u32 __user *uaddr, int op, u32 val, union ktime *timeout,
126 u32 __user *uaddr2, u32 val2, u32 val3);
127
128extern int
129handle_futex_death(u32 __user *uaddr, struct task_struct *curr, int pi);
130
131/*
132 * Futexes are matched on equal values of this key.
133 * The key type depends on whether it's a shared or private mapping.
134 * Don't rearrange members without looking at hash_futex().
135 *
136 * offset is aligned to a multiple of sizeof(u32) (== 4) by definition.
137 * We use the two low order bits of offset to tell what is the kind of key :
138 * 00 : Private process futex (PTHREAD_PROCESS_PRIVATE)
139 * (no reference on an inode or mm)
140 * 01 : Shared futex (PTHREAD_PROCESS_SHARED)
141 * mapped on a file (reference on the underlying inode)
142 * 10 : Shared futex (PTHREAD_PROCESS_SHARED)
143 * (but private mapping on an mm, and reference taken on it)
144*/
145
146#define FUT_OFF_INODE 1 /* We set bit 0 if key has a reference on inode */
147#define FUT_OFF_MMSHARED 2 /* We set bit 1 if key has a reference on mm */
148
149union futex_key {
150 struct {
151 unsigned long pgoff;
152 struct inode *inode;
153 int offset;
154 } shared;
155 struct {
156 unsigned long address;
157 struct mm_struct *mm;
158 int offset;
159 } private;
160 struct {
161 unsigned long word;
162 void *ptr;
163 int offset;
164 } both;
165};
166
167#ifdef CONFIG_FUTEX
168extern void exit_robust_list(struct task_struct *curr);
169extern void exit_pi_state_list(struct task_struct *curr);
170extern int futex_cmpxchg_enabled;
171#else
172static inline void exit_robust_list(struct task_struct *curr)
173{
174}
175static inline void exit_pi_state_list(struct task_struct *curr)
176{
177}
178#endif
179#endif /* __KERNEL__ */
180
181#define FUTEX_OP_SET 0 /* *(int *)UADDR2 = OPARG; */
182#define FUTEX_OP_ADD 1 /* *(int *)UADDR2 += OPARG; */
183#define FUTEX_OP_OR 2 /* *(int *)UADDR2 |= OPARG; */
184#define FUTEX_OP_ANDN 3 /* *(int *)UADDR2 &= ~OPARG; */
185#define FUTEX_OP_XOR 4 /* *(int *)UADDR2 ^= OPARG; */
186
187#define FUTEX_OP_OPARG_SHIFT 8 /* Use (1 << OPARG) instead of OPARG. */
188
189#define FUTEX_OP_CMP_EQ 0 /* if (oldval == CMPARG) wake */
190#define FUTEX_OP_CMP_NE 1 /* if (oldval != CMPARG) wake */
191#define FUTEX_OP_CMP_LT 2 /* if (oldval < CMPARG) wake */
192#define FUTEX_OP_CMP_LE 3 /* if (oldval <= CMPARG) wake */
193#define FUTEX_OP_CMP_GT 4 /* if (oldval > CMPARG) wake */
194#define FUTEX_OP_CMP_GE 5 /* if (oldval >= CMPARG) wake */
195
196/* FUTEX_WAKE_OP will perform atomically
197 int oldval = *(int *)UADDR2;
198 *(int *)UADDR2 = oldval OP OPARG;
199 if (oldval CMP CMPARG)
200 wake UADDR2; */
201
202#define FUTEX_OP(op, oparg, cmp, cmparg) \
203 (((op & 0xf) << 28) | ((cmp & 0xf) << 24) \
204 | ((oparg & 0xfff) << 12) | (cmparg & 0xfff))
205
206#endif