1 #ifndef _LINUX_FUTEX_H
2 #define _LINUX_FUTEX_H
3
4 #include <linux/compiler.h>
5 #include <linux/types.h>
6
7 struct inode;
8 struct mm_struct;
9 struct task_struct;
10 union 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_CLOCK_REALTIME 256
29 #define FUTEX_CMD_MASK ~(FUTEX_PRIVATE_FLAG | FUTEX_CLOCK_REALTIME)
30
31 #define FUTEX_WAIT_PRIVATE (FUTEX_WAIT | FUTEX_PRIVATE_FLAG)
32 #define FUTEX_WAKE_PRIVATE (FUTEX_WAKE | FUTEX_PRIVATE_FLAG)
33 #define FUTEX_REQUEUE_PRIVATE (FUTEX_REQUEUE | FUTEX_PRIVATE_FLAG)
34 #define FUTEX_CMP_REQUEUE_PRIVATE (FUTEX_CMP_REQUEUE | FUTEX_PRIVATE_FLAG)
35 #define FUTEX_WAKE_OP_PRIVATE (FUTEX_WAKE_OP | FUTEX_PRIVATE_FLAG)
36 #define FUTEX_LOCK_PI_PRIVATE (FUTEX_LOCK_PI | FUTEX_PRIVATE_FLAG)
37 #define FUTEX_UNLOCK_PI_PRIVATE (FUTEX_UNLOCK_PI | FUTEX_PRIVATE_FLAG)
38 #define FUTEX_TRYLOCK_PI_PRIVATE (FUTEX_TRYLOCK_PI | FUTEX_PRIVATE_FLAG)
39 #define FUTEX_WAIT_BITSET_PRIVATE (FUTEX_WAIT_BITS | FUTEX_PRIVATE_FLAG)
40 #define FUTEX_WAKE_BITSET_PRIVATE (FUTEX_WAKE_BITS | FUTEX_PRIVATE_FLAG)
41
42 /*
43 * Support for robust futexes: the kernel cleans up held futexes at
44 * thread exit time.
45 */
46
47 /*
48 * Per-lock list entry - embedded in user-space locks, somewhere close
49 * to the futex field. (Note: user-space uses a double-linked list to
50 * achieve O(1) list add and remove, but the kernel only needs to know
51 * about the forward link)
52 *
53 * NOTE: this structure is part of the syscall ABI, and must not be
54 * changed.
55 */
56 struct robust_list {
57 struct robust_list __user *next;
58 };
59
60 /*
61 * Per-thread list head:
62 *
63 * NOTE: this structure is part of the syscall ABI, and must only be
64 * changed if the change is first communicated with the glibc folks.
65 * (When an incompatible change is done, we'll increase the structure
66 * size, which glibc will detect)
67 */
68 struct robust_list_head {
69 /*
70 * The head of the list. Points back to itself if empty:
71 */
72 struct robust_list list;
73
74 /*
75 * This relative offset is set by user-space, it gives the kernel
76 * the relative position of the futex field to examine. This way
77 * we keep userspace flexible, to freely shape its data-structure,
78 * without hardcoding any particular offset into the kernel:
79 */
80 long futex_offset;
81
82 /*
83 * The death of the thread may race with userspace setting
84 * up a lock's links. So to handle this race, userspace first
85 * sets this field to the address of the to-be-taken lock,
86 * then does the lock acquire, and then adds itself to the
87 * list, and then clears this field. Hence the kernel will
88 * always have full knowledge of all locks that the thread
89 * _might_ have taken. We check the owner TID in any case,
90 * so only truly owned locks will be handled.
91 */
92 struct robust_list __user *list_op_pending;
93 };
94
95 /*
96 * Are there any waiters for this robust futex:
97 */
98 #define FUTEX_WAITERS 0x80000000
99
100 /*
101 * The kernel signals via this bit that a thread holding a futex
102 * has exited without unlocking the futex. The kernel also does
103 * a FUTEX_WAKE on such futexes, after setting the bit, to wake
104 * up any possible waiters:
105 */
106 #define FUTEX_OWNER_DIED 0x40000000
107
108 /*
109 * The rest of the robust-futex field is for the TID:
110 */
111 #define FUTEX_TID_MASK 0x3fffffff
112
113 /*
114 * This limit protects against a deliberately circular list.
115 * (Not worth introducing an rlimit for it)
116 */
117 #define ROBUST_LIST_LIMIT 2048
118
119 /*
120 * bitset with all bits set for the FUTEX_xxx_BITSET OPs to request a
121 * match of any bit.
122 */
123 #define FUTEX_BITSET_MATCH_ANY 0xffffffff
124
125 #ifdef __KERNEL__
126 long do_futex(u32 __user *uaddr, int op, u32 val, union ktime *timeout,
127 u32 __user *uaddr2, u32 val2, u32 val3);
128
129 extern int
130 handle_futex_death(u32 __user *uaddr, struct task_struct *curr, int pi);
131
132 /*
133 * Futexes are matched on equal values of this key.
134 * The key type depends on whether it's a shared or private mapping.
135 * Don't rearrange members without looking at hash_futex().
136 *
137 * offset is aligned to a multiple of sizeof(u32) (== 4) by definition.
138 * We use the two low order bits of offset to tell what is the kind of key :
139 * 00 : Private process futex (PTHREAD_PROCESS_PRIVATE)
140 * (no reference on an inode or mm)
141 * 01 : Shared futex (PTHREAD_PROCESS_SHARED)
142 * mapped on a file (reference on the underlying inode)
143 * 10 : Shared futex (PTHREAD_PROCESS_SHARED)
144 * (but private mapping on an mm, and reference taken on it)
145 */
146
147 #define FUT_OFF_INODE 1 /* We set bit 0 if key has a reference on inode */
148 #define FUT_OFF_MMSHARED 2 /* We set bit 1 if key has a reference on mm */
149
150 union futex_key {
151 struct {
152 unsigned long pgoff;
153 struct inode *inode;
154 int offset;
155 } shared;
156 struct {
157 unsigned long address;
158 struct mm_struct *mm;
159 int offset;
160 } private;
161 struct {
162 unsigned long word;
163 void *ptr;
164 int offset;
165 } both;
166 };
167
168 #define FUTEX_KEY_INIT (union futex_key) { .both = { .ptr = NULL } }
169
170 #ifdef CONFIG_FUTEX
171 extern void exit_robust_list(struct task_struct *curr);
172 extern void exit_pi_state_list(struct task_struct *curr);
173 extern int futex_cmpxchg_enabled;
174 #else
exit_robust_list(struct task_struct * curr)175 static inline void exit_robust_list(struct task_struct *curr)
176 {
177 }
exit_pi_state_list(struct task_struct * curr)178 static inline void exit_pi_state_list(struct task_struct *curr)
179 {
180 }
181 #endif
182 #endif /* __KERNEL__ */
183
184 #define FUTEX_OP_SET 0 /* *(int *)UADDR2 = OPARG; */
185 #define FUTEX_OP_ADD 1 /* *(int *)UADDR2 += OPARG; */
186 #define FUTEX_OP_OR 2 /* *(int *)UADDR2 |= OPARG; */
187 #define FUTEX_OP_ANDN 3 /* *(int *)UADDR2 &= ~OPARG; */
188 #define FUTEX_OP_XOR 4 /* *(int *)UADDR2 ^= OPARG; */
189
190 #define FUTEX_OP_OPARG_SHIFT 8 /* Use (1 << OPARG) instead of OPARG. */
191
192 #define FUTEX_OP_CMP_EQ 0 /* if (oldval == CMPARG) wake */
193 #define FUTEX_OP_CMP_NE 1 /* if (oldval != CMPARG) wake */
194 #define FUTEX_OP_CMP_LT 2 /* if (oldval < CMPARG) wake */
195 #define FUTEX_OP_CMP_LE 3 /* if (oldval <= CMPARG) wake */
196 #define FUTEX_OP_CMP_GT 4 /* if (oldval > CMPARG) wake */
197 #define FUTEX_OP_CMP_GE 5 /* if (oldval >= CMPARG) wake */
198
199 /* FUTEX_WAKE_OP will perform atomically
200 int oldval = *(int *)UADDR2;
201 *(int *)UADDR2 = oldval OP OPARG;
202 if (oldval CMP CMPARG)
203 wake UADDR2; */
204
205 #define FUTEX_OP(op, oparg, cmp, cmparg) \
206 (((op & 0xf) << 28) | ((cmp & 0xf) << 24) \
207 | ((oparg & 0xfff) << 12) | (cmparg & 0xfff))
208
209 #endif
210