1#ifndef _LINUX_FUTEX_H
2#define _LINUX_FUTEX_H
3
4#include <linux/sched.h>
5
6union ktime;
7
8/* Second argument to futex syscall */
9
10
11#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
17#define FUTEX_LOCK_PI		6
18#define FUTEX_UNLOCK_PI		7
19#define FUTEX_TRYLOCK_PI	8
20
21#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
33/*
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/*
100 * The rest of the robust-futex field is for the TID:
101 */
102#define FUTEX_TID_MASK		0x3fffffff
103
104/*
105 * This limit protects against a deliberately circular list.
106 * (Not worth introducing an rlimit for it)
107 */
108#define ROBUST_LIST_LIMIT	2048
109
110#ifdef __KERNEL__
111long do_futex(u32 __user *uaddr, int op, u32 val, union ktime *timeout,
112	      u32 __user *uaddr2, u32 val2, u32 val3);
113
114extern int
115handle_futex_death(u32 __user *uaddr, struct task_struct *curr, int pi);
116
117/*
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.
123 * 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
135union 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};
152int get_futex_key(u32 __user *uaddr, struct rw_semaphore *shared,
153		  union futex_key *key);
154void get_futex_key_refs(union futex_key *key);
155void drop_futex_key_refs(union futex_key *key);
156
157#ifdef CONFIG_FUTEX
158extern void exit_robust_list(struct task_struct *curr);
159extern void exit_pi_state_list(struct task_struct *curr);
160#else
161static inline void exit_robust_list(struct task_struct *curr)
162{
163}
164static inline void exit_pi_state_list(struct task_struct *curr)
165{
166}
167#endif
168#endif /* __KERNEL__ */
169
170#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
195#endif
196