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Linus Torvalds1da177e2005-04-16 15:20:36 -07001#ifndef _LINUX_FUTEX_H
2#define _LINUX_FUTEX_H
3
Alexey Dobriyan286100a2008-01-25 21:08:34 +01004#include <linux/compiler.h>
5#include <linux/types.h>
Ingo Molnar0771dfe2006-03-27 01:16:22 -08006
Alexey Dobriyan286100a2008-01-25 21:08:34 +01007struct inode;
8struct mm_struct;
9struct task_struct;
Pierre Peifferc19384b2007-05-09 02:35:02 -070010union ktime;
11
Linus Torvalds1da177e2005-04-16 15:20:36 -070012/* Second argument to futex syscall */
13
14
Jakub Jelinek4732efb2005-09-06 15:16:25 -070015#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
Ingo Molnarc87e2832006-06-27 02:54:58 -070021#define FUTEX_LOCK_PI 6
22#define FUTEX_UNLOCK_PI 7
23#define FUTEX_TRYLOCK_PI 8
Thomas Gleixnercd689982008-02-01 17:45:14 +010024#define FUTEX_WAIT_BITSET 9
25#define FUTEX_WAKE_BITSET 10
Darren Hart52400ba2009-04-03 13:40:49 -070026#define FUTEX_WAIT_REQUEUE_PI 11
Darren Hartba9c22f2009-04-20 22:22:22 -070027#define FUTEX_CMP_REQUEUE_PI 12
Linus Torvalds1da177e2005-04-16 15:20:36 -070028
Eric Dumazet34f01cc2007-05-09 02:35:04 -070029#define FUTEX_PRIVATE_FLAG 128
Thomas Gleixner1acdac12008-11-20 10:02:53 -080030#define FUTEX_CLOCK_REALTIME 256
31#define FUTEX_CMD_MASK ~(FUTEX_PRIVATE_FLAG | FUTEX_CLOCK_REALTIME)
Eric Dumazet34f01cc2007-05-09 02:35:04 -070032
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)
Thomas Gleixnercd689982008-02-01 17:45:14 +010041#define FUTEX_WAIT_BITSET_PRIVATE (FUTEX_WAIT_BITS | FUTEX_PRIVATE_FLAG)
42#define FUTEX_WAKE_BITSET_PRIVATE (FUTEX_WAKE_BITS | FUTEX_PRIVATE_FLAG)
Darren Hart52400ba2009-04-03 13:40:49 -070043#define FUTEX_WAIT_REQUEUE_PI_PRIVATE (FUTEX_WAIT_REQUEUE_PI | \
44 FUTEX_PRIVATE_FLAG)
Darren Hart52400ba2009-04-03 13:40:49 -070045#define FUTEX_CMP_REQUEUE_PI_PRIVATE (FUTEX_CMP_REQUEUE_PI | \
46 FUTEX_PRIVATE_FLAG)
Eric Dumazet34f01cc2007-05-09 02:35:04 -070047
Ingo Molnar0771dfe2006-03-27 01:16:22 -080048/*
49 * Support for robust futexes: the kernel cleans up held futexes at
50 * thread exit time.
51 */
52
53/*
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)
58 *
59 * NOTE: this structure is part of the syscall ABI, and must not be
60 * changed.
61 */
62struct robust_list {
63 struct robust_list __user *next;
64};
65
66/*
67 * Per-thread list head:
68 *
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)
73 */
74struct robust_list_head {
75 /*
76 * The head of the list. Points back to itself if empty:
77 */
78 struct robust_list list;
79
80 /*
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:
85 */
86 long futex_offset;
87
88 /*
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.
97 */
98 struct robust_list __user *list_op_pending;
99};
100
101/*
102 * Are there any waiters for this robust futex:
103 */
104#define FUTEX_WAITERS 0x80000000
105
106/*
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:
111 */
112#define FUTEX_OWNER_DIED 0x40000000
113
114/*
Ingo Molnar0771dfe2006-03-27 01:16:22 -0800115 * The rest of the robust-futex field is for the TID:
116 */
Thomas Gleixnerbd197232007-06-17 21:11:10 +0200117#define FUTEX_TID_MASK 0x3fffffff
Ingo Molnar0771dfe2006-03-27 01:16:22 -0800118
119/*
Ingo Molnar76b81e22006-03-27 01:16:28 -0800120 * This limit protects against a deliberately circular list.
121 * (Not worth introducing an rlimit for it)
Ingo Molnar0771dfe2006-03-27 01:16:22 -0800122 */
Ingo Molnar76b81e22006-03-27 01:16:28 -0800123#define ROBUST_LIST_LIMIT 2048
Ingo Molnar0771dfe2006-03-27 01:16:22 -0800124
Thomas Gleixnercd689982008-02-01 17:45:14 +0100125/*
126 * bitset with all bits set for the FUTEX_xxx_BITSET OPs to request a
127 * match of any bit.
128 */
129#define FUTEX_BITSET_MATCH_ANY 0xffffffff
130
David Woodhouse58f64d82006-12-10 02:19:11 -0800131#ifdef __KERNEL__
Pierre Peifferc19384b2007-05-09 02:35:02 -0700132long do_futex(u32 __user *uaddr, int op, u32 val, union ktime *timeout,
Ingo Molnare2970f22006-06-27 02:54:47 -0700133 u32 __user *uaddr2, u32 val2, u32 val3);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700134
Ingo Molnare3f2dde2006-07-29 05:17:57 +0200135extern int
136handle_futex_death(u32 __user *uaddr, struct task_struct *curr, int pi);
Ingo Molnar0771dfe2006-03-27 01:16:22 -0800137
Rusty Russell9adef582007-05-08 00:26:42 -0700138/*
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().
142 *
143 * offset is aligned to a multiple of sizeof(u32) (== 4) by definition.
Eric Dumazet34f01cc2007-05-09 02:35:04 -0700144 * 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)
151*/
152
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 */
155
Rusty Russell9adef582007-05-08 00:26:42 -0700156union futex_key {
157 struct {
158 unsigned long pgoff;
159 struct inode *inode;
160 int offset;
161 } shared;
162 struct {
163 unsigned long address;
164 struct mm_struct *mm;
165 int offset;
166 } private;
167 struct {
168 unsigned long word;
169 void *ptr;
170 int offset;
171 } both;
172};
Rusty Russell9adef582007-05-08 00:26:42 -0700173
Peter Zijlstra38d47c12008-09-26 19:32:20 +0200174#define FUTEX_KEY_INIT (union futex_key) { .both = { .ptr = NULL } }
175
Ingo Molnar0771dfe2006-03-27 01:16:22 -0800176#ifdef CONFIG_FUTEX
177extern void exit_robust_list(struct task_struct *curr);
Ingo Molnarc87e2832006-06-27 02:54:58 -0700178extern void exit_pi_state_list(struct task_struct *curr);
Thomas Gleixnera0c1e902008-02-23 15:23:57 -0800179extern int futex_cmpxchg_enabled;
Ingo Molnar0771dfe2006-03-27 01:16:22 -0800180#else
181static inline void exit_robust_list(struct task_struct *curr)
182{
183}
Ingo Molnarc87e2832006-06-27 02:54:58 -0700184static inline void exit_pi_state_list(struct task_struct *curr)
185{
186}
Ingo Molnar0771dfe2006-03-27 01:16:22 -0800187#endif
David Woodhouse58f64d82006-12-10 02:19:11 -0800188#endif /* __KERNEL__ */
Ingo Molnar0771dfe2006-03-27 01:16:22 -0800189
Jakub Jelinek4732efb2005-09-06 15:16:25 -0700190#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; */
195
196#define FUTEX_OP_OPARG_SHIFT 8 /* Use (1 << OPARG) instead of OPARG. */
197
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 */
204
205/* FUTEX_WAKE_OP will perform atomically
206 int oldval = *(int *)UADDR2;
207 *(int *)UADDR2 = oldval OP OPARG;
208 if (oldval CMP CMPARG)
209 wake UADDR2; */
210
211#define FUTEX_OP(op, oparg, cmp, cmparg) \
212 (((op & 0xf) << 28) | ((cmp & 0xf) << 24) \
213 | ((oparg & 0xfff) << 12) | (cmparg & 0xfff))
214
Linus Torvalds1da177e2005-04-16 15:20:36 -0700215#endif