1/* $NetBSD: futex.h,v 1.7 2025/03/05 12:02:00 riastradh Exp $ */
2
3/*-
4 * Copyright (c) 2018, 2019 The NetBSD Foundation, Inc.
5 * All rights reserved.
6 *
7 * This code is derived from software contributed to The NetBSD Foundation
8 * by Taylor R. Campbell and Jason R. Thorpe.
9 *
10 * Redistribution and use in source and binary forms, with or without
11 * modification, are permitted provided that the following conditions
12 * are met:
13 * 1. Redistributions of source code must retain the above copyright
14 * notice, this list of conditions and the following disclaimer.
15 * 2. Redistributions in binary form must reproduce the above copyright
16 * notice, this list of conditions and the following disclaimer in the
17 * documentation and/or other materials provided with the distribution.
18 *
19 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
20 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
21 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
22 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
23 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
24 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
25 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
26 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
27 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
28 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
29 * POSSIBILITY OF SUCH DAMAGE.
30 */
31
32/*-
33 * Copyright (c) 2005 Emmanuel Dreyfus, all rights reserved.
34 *
35 * Redistribution and use in source and binary forms, with or without
36 * modification, are permitted provided that the following conditions
37 * are met:
38 * 1. Redistributions of source code must retain the above copyright
39 * notice, this list of conditions and the following disclaimer.
40 * 2. Redistributions in binary form must reproduce the above copyright
41 * notice, this list of conditions and the following disclaimer in the
42 * documentation and/or other materials provided with the distribution.
43 * 3. All advertising materials mentioning features or use of this software
44 * must display the following acknowledgement:
45 * This product includes software developed by Emmanuel Dreyfus
46 * 4. The name of the author may not be used to endorse or promote
47 * products derived from this software without specific prior written
48 * permission.
49 *
50 * THIS SOFTWARE IS PROVIDED BY THE THE AUTHOR AND CONTRIBUTORS ``AS IS''
51 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
52 * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
53 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS
54 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
55 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
56 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
57 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
58 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
59 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
60 * POSSIBILITY OF SUCH DAMAGE.
61 */
62
63#ifndef _SYS_FUTEX_H_
64#define _SYS_FUTEX_H_
65
66/*
67 * Definitions for the __futex(2) synchronization primitive.
68 *
69 * These definitions are intended to be ABI-compatible with the
70 * Linux futex(2) system call.
71 */
72
73#include <sys/timespec.h>
74
75#define FUTEX_WAIT 0
76#define FUTEX_WAKE 1
77#define FUTEX_FD 2
78#define FUTEX_REQUEUE 3
79#define FUTEX_CMP_REQUEUE 4
80#define FUTEX_WAKE_OP 5
81#define FUTEX_LOCK_PI 6
82#define FUTEX_UNLOCK_PI 7
83#define FUTEX_TRYLOCK_PI 8
84#define FUTEX_WAIT_BITSET 9
85#define FUTEX_WAKE_BITSET 10
86#define FUTEX_WAIT_REQUEUE_PI 11
87#define FUTEX_CMP_REQUEUE_PI 12
88
89#define FUTEX_PRIVATE_FLAG __BIT(7)
90#define FUTEX_CLOCK_REALTIME __BIT(8)
91
92#define FUTEX_CMD_MASK \
93 (~(FUTEX_PRIVATE_FLAG|FUTEX_CLOCK_REALTIME))
94
95#define FUTEX_OP_OP_MASK __BITS(28,31)
96#define FUTEX_OP_CMP_MASK __BITS(24,27)
97#define FUTEX_OP_OPARG_MASK __BITS(12,23)
98#define FUTEX_OP_CMPARG_MASK __BITS(0,11)
99
100#define FUTEX_OP(op, oparg, cmp, cmparg) \
101 (__SHIFTIN((op) & 0xf, FUTEX_OP_OP_MASK) |\
102 __SHIFTIN((oparg) & 0xfff, FUTEX_OP_OPARG_MASK)|\
103 __SHIFTIN((cmp) & 0xf, FUTEX_OP_CMP_MASK) |\
104 __SHIFTIN((cmparg) & 0xfff, FUTEX_OP_CMPARG_MASK))
105
106#define FUTEX_OP_SET 0
107#define FUTEX_OP_ADD 1
108#define FUTEX_OP_OR 2
109#define FUTEX_OP_ANDN 3
110#define FUTEX_OP_XOR 4
111#define FUTEX_OP_OPARG_SHIFT 8
112
113#define FUTEX_OP_CMP_EQ 0
114#define FUTEX_OP_CMP_NE 1
115#define FUTEX_OP_CMP_LT 2
116#define FUTEX_OP_CMP_LE 3
117#define FUTEX_OP_CMP_GT 4
118#define FUTEX_OP_CMP_GE 5
119
120/*
121 * FUTEX_SYNCOBJ_0 and FUTEX_SYNCOBJ_1 are extensions to the Linux
122 * futex API that are reserved for individual consumers of futexes
123 * to define information specific to that synchronzation object.
124 * Note that as a result there is a system-wide upper limit of
125 * 268,435,455 threads (as opposed to 1,073,741,823).
126 */
127#define FUTEX_WAITERS ((int)__BIT(31))
128#define FUTEX_OWNER_DIED ((int)__BIT(30))
129#define FUTEX_SYNCOBJ_1 ((int)__BIT(29))
130#define FUTEX_SYNCOBJ_0 ((int)__BIT(28))
131#define FUTEX_TID_MASK ((int)__BITS(0,27))
132
133#define FUTEX_BITSET_MATCH_ANY ((int)__BITS(0,31))
134
135/*
136 * The robust futex ABI consists of an array of 3 longwords, the address
137 * of which is registered with the kernel on a per-thread basis:
138 *
139 * 0: A pointer to a singly-linked list of "lock entries". If the
140 * list is empty, this points back to the list itself.
141 *
142 * 1: An offset from address of the "lock entry" to the 32-bit futex
143 * word associated with that lock entry (may be negative).
144 *
145 * 2: A "pending" pointer, for locks that are in the process of being
146 * acquired or released.
147 *
148 * PI futexes are handled slightly differently. User-space indicates
149 * an entry is for a PI futex by setting the last-significant bit.
150 */
151#define _FUTEX_ROBUST_HEAD_LIST 0
152#define _FUTEX_ROBUST_HEAD_OFFSET 1
153#define _FUTEX_ROBUST_HEAD_PENDING 2
154#define _FUTEX_ROBUST_HEAD_NWORDS 3
155#define _FUTEX_ROBUST_HEAD_SIZE (_FUTEX_ROBUST_HEAD_NWORDS * \
156 sizeof(u_long))
157#define _FUTEX_ROBUST_HEAD_SIZE32 (_FUTEX_ROBUST_HEAD_NWORDS * \
158 sizeof(uint32_t))
159#define _FUTEX_ROBUST_ENTRY_PI __BIT(0)
160
161#ifdef __LIBC_FUTEX_PRIVATE
162struct futex_robust_list {
163 struct futex_robust_list *next;
164};
165
166struct futex_robust_list_head {
167 struct futex_robust_list list;
168 long futex_offset;
169 struct futex_robust_list *pending_list;
170};
171#endif /* __LIBC_FUTEX_PRIVATE */
172
173#ifdef _KERNEL
174struct lwp;
175
176int futex_robust_head_lookup(struct lwp *, lwpid_t, void **);
177void futex_release_all_lwp(struct lwp *);
178int do_futex(int *, int, int, const struct timespec *, int *, int,
179 int, register_t *);
180void futex_sys_init(void);
181void futex_sys_fini(void);
182#endif /* _KERNEL */
183
184#endif /* ! _SYS_FUTEX_H_ */