4 #include <linux/compiler.h>
5 #include <linux/types.h>
12 /* Second argument to futex syscall */
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 #define FUTEX_WAIT_REQUEUE_PI 11
27 #define FUTEX_CMP_REQUEUE_PI 12
29 #define FUTEX_PRIVATE_FLAG 128
30 #define FUTEX_CLOCK_REALTIME 256
31 #define FUTEX_CMD_MASK ~(FUTEX_PRIVATE_FLAG | FUTEX_CLOCK_REALTIME)
33 #define FUTEX_WAIT_PRIVATE (FUTEX_WAIT | FUTEX_PRIVATE_FLAG)
34 #define FUTEX_WAKE_PRIVATE (FUTEX_WAKE | FUTEX_PRIVATE_FLAG)
35 #define FUTEX_REQUEUE_PRIVATE (FUTEX_REQUEUE | FUTEX_PRIVATE_FLAG)
36 #define FUTEX_CMP_REQUEUE_PRIVATE (FUTEX_CMP_REQUEUE | FUTEX_PRIVATE_FLAG)
37 #define FUTEX_WAKE_OP_PRIVATE (FUTEX_WAKE_OP | FUTEX_PRIVATE_FLAG)
38 #define FUTEX_LOCK_PI_PRIVATE (FUTEX_LOCK_PI | FUTEX_PRIVATE_FLAG)
39 #define FUTEX_UNLOCK_PI_PRIVATE (FUTEX_UNLOCK_PI | FUTEX_PRIVATE_FLAG)
40 #define FUTEX_TRYLOCK_PI_PRIVATE (FUTEX_TRYLOCK_PI | FUTEX_PRIVATE_FLAG)
41 #define FUTEX_WAIT_BITSET_PRIVATE (FUTEX_WAIT_BITS | FUTEX_PRIVATE_FLAG)
42 #define FUTEX_WAKE_BITSET_PRIVATE (FUTEX_WAKE_BITS | FUTEX_PRIVATE_FLAG)
43 #define FUTEX_WAIT_REQUEUE_PI_PRIVATE (FUTEX_WAIT_REQUEUE_PI | \
45 #define FUTEX_CMP_REQUEUE_PI_PRIVATE (FUTEX_CMP_REQUEUE_PI | \
49 * Support for robust futexes: the kernel cleans up held futexes at
54 * Per-lock list entry - embedded in user-space locks, somewhere close
55 * to the futex field. (Note: user-space uses a double-linked list to
56 * achieve O(1) list add and remove, but the kernel only needs to know
57 * about the forward link)
59 * NOTE: this structure is part of the syscall ABI, and must not be
63 struct robust_list __user *next;
67 * Per-thread list head:
69 * NOTE: this structure is part of the syscall ABI, and must only be
70 * changed if the change is first communicated with the glibc folks.
71 * (When an incompatible change is done, we'll increase the structure
72 * size, which glibc will detect)
74 struct robust_list_head {
76 * The head of the list. Points back to itself if empty:
78 struct robust_list list;
81 * This relative offset is set by user-space, it gives the kernel
82 * the relative position of the futex field to examine. This way
83 * we keep userspace flexible, to freely shape its data-structure,
84 * without hardcoding any particular offset into the kernel:
89 * The death of the thread may race with userspace setting
90 * up a lock's links. So to handle this race, userspace first
91 * sets this field to the address of the to-be-taken lock,
92 * then does the lock acquire, and then adds itself to the
93 * list, and then clears this field. Hence the kernel will
94 * always have full knowledge of all locks that the thread
95 * _might_ have taken. We check the owner TID in any case,
96 * so only truly owned locks will be handled.
98 struct robust_list __user *list_op_pending;
102 * Are there any waiters for this robust futex:
104 #define FUTEX_WAITERS 0x80000000
107 * The kernel signals via this bit that a thread holding a futex
108 * has exited without unlocking the futex. The kernel also does
109 * a FUTEX_WAKE on such futexes, after setting the bit, to wake
110 * up any possible waiters:
112 #define FUTEX_OWNER_DIED 0x40000000
115 * The rest of the robust-futex field is for the TID:
117 #define FUTEX_TID_MASK 0x3fffffff
120 * This limit protects against a deliberately circular list.
121 * (Not worth introducing an rlimit for it)
123 #define ROBUST_LIST_LIMIT 2048
126 * bitset with all bits set for the FUTEX_xxx_BITSET OPs to request a
129 #define FUTEX_BITSET_MATCH_ANY 0xffffffff
132 long do_futex(u32 __user *uaddr, int op, u32 val, union ktime *timeout,
133 u32 __user *uaddr2, u32 val2, u32 val3);
136 handle_futex_death(u32 __user *uaddr, struct task_struct *curr, int pi);
139 * Futexes are matched on equal values of this key.
140 * The key type depends on whether it's a shared or private mapping.
141 * Don't rearrange members without looking at hash_futex().
143 * offset is aligned to a multiple of sizeof(u32) (== 4) by definition.
144 * We use the two low order bits of offset to tell what is the kind of key :
145 * 00 : Private process futex (PTHREAD_PROCESS_PRIVATE)
146 * (no reference on an inode or mm)
147 * 01 : Shared futex (PTHREAD_PROCESS_SHARED)
148 * mapped on a file (reference on the underlying inode)
149 * 10 : Shared futex (PTHREAD_PROCESS_SHARED)
150 * (but private mapping on an mm, and reference taken on it)
153 #define FUT_OFF_INODE 1 /* We set bit 0 if key has a reference on inode */
154 #define FUT_OFF_MMSHARED 2 /* We set bit 1 if key has a reference on mm */
163 unsigned long address;
164 struct mm_struct *mm;
174 #define FUTEX_KEY_INIT (union futex_key) { .both = { .ptr = NULL } }
177 extern void exit_robust_list(struct task_struct *curr);
178 extern void exit_pi_state_list(struct task_struct *curr);
179 extern int futex_cmpxchg_enabled;
181 static inline void exit_robust_list(struct task_struct *curr)
184 static inline void exit_pi_state_list(struct task_struct *curr)
188 #endif /* __KERNEL__ */
190 #define FUTEX_OP_SET 0 /* *(int *)UADDR2 = OPARG; */
191 #define FUTEX_OP_ADD 1 /* *(int *)UADDR2 += OPARG; */
192 #define FUTEX_OP_OR 2 /* *(int *)UADDR2 |= OPARG; */
193 #define FUTEX_OP_ANDN 3 /* *(int *)UADDR2 &= ~OPARG; */
194 #define FUTEX_OP_XOR 4 /* *(int *)UADDR2 ^= OPARG; */
196 #define FUTEX_OP_OPARG_SHIFT 8 /* Use (1 << OPARG) instead of OPARG. */
198 #define FUTEX_OP_CMP_EQ 0 /* if (oldval == CMPARG) wake */
199 #define FUTEX_OP_CMP_NE 1 /* if (oldval != CMPARG) wake */
200 #define FUTEX_OP_CMP_LT 2 /* if (oldval < CMPARG) wake */
201 #define FUTEX_OP_CMP_LE 3 /* if (oldval <= CMPARG) wake */
202 #define FUTEX_OP_CMP_GT 4 /* if (oldval > CMPARG) wake */
203 #define FUTEX_OP_CMP_GE 5 /* if (oldval >= CMPARG) wake */
205 /* FUTEX_WAKE_OP will perform atomically
206 int oldval = *(int *)UADDR2;
207 *(int *)UADDR2 = oldval OP OPARG;
208 if (oldval CMP CMPARG)
211 #define FUTEX_OP(op, oparg, cmp, cmparg) \
212 (((op & 0xf) << 28) | ((cmp & 0xf) << 24) \
213 | ((oparg & 0xfff) << 12) | (cmparg & 0xfff))