1 | /* Low-level locking access to futex facilities. Linux version. |
2 | Copyright (C) 2005-2019 Free Software Foundation, Inc. |
3 | This file is part of the GNU C Library. |
4 | |
5 | The GNU C Library is free software; you can redistribute it and/or |
6 | modify it under the terms of the GNU Lesser General Public |
7 | License as published by the Free Software Foundation; either |
8 | version 2.1 of the License, or (at your option) any later version. |
9 | |
10 | The GNU C Library is distributed in the hope that it will be useful, |
11 | but WITHOUT ANY WARRANTY; without even the implied warranty of |
12 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
13 | Lesser General Public License for more details. |
14 | |
15 | You should have received a copy of the GNU Lesser General Public |
16 | License along with the GNU C Library. If not, see |
17 | <http://www.gnu.org/licenses/>. */ |
18 | |
19 | #ifndef _LOWLEVELLOCK_FUTEX_H |
20 | #define _LOWLEVELLOCK_FUTEX_H 1 |
21 | |
22 | #ifndef __ASSEMBLER__ |
23 | #include <sysdep.h> |
24 | #include <sysdep-cancel.h> |
25 | #include <kernel-features.h> |
26 | #endif |
27 | |
28 | #define FUTEX_WAIT 0 |
29 | #define FUTEX_WAKE 1 |
30 | #define FUTEX_REQUEUE 3 |
31 | #define FUTEX_CMP_REQUEUE 4 |
32 | #define FUTEX_WAKE_OP 5 |
33 | #define FUTEX_OP_CLEAR_WAKE_IF_GT_ONE ((4 << 24) | 1) |
34 | #define FUTEX_LOCK_PI 6 |
35 | #define FUTEX_UNLOCK_PI 7 |
36 | #define FUTEX_TRYLOCK_PI 8 |
37 | #define FUTEX_WAIT_BITSET 9 |
38 | #define FUTEX_WAKE_BITSET 10 |
39 | #define FUTEX_WAIT_REQUEUE_PI 11 |
40 | #define FUTEX_CMP_REQUEUE_PI 12 |
41 | #define FUTEX_PRIVATE_FLAG 128 |
42 | #define FUTEX_CLOCK_REALTIME 256 |
43 | |
44 | #define FUTEX_BITSET_MATCH_ANY 0xffffffff |
45 | |
46 | /* Values for 'private' parameter of locking macros. Yes, the |
47 | definition seems to be backwards. But it is not. The bit will be |
48 | reversed before passing to the system call. */ |
49 | #define LLL_PRIVATE 0 |
50 | #define LLL_SHARED FUTEX_PRIVATE_FLAG |
51 | |
52 | #ifndef __ASSEMBLER__ |
53 | |
54 | #if IS_IN (libc) || IS_IN (rtld) |
55 | /* In libc.so or ld.so all futexes are private. */ |
56 | # define __lll_private_flag(fl, private) \ |
57 | ({ \ |
58 | /* Prevent warnings in callers of this macro. */ \ |
59 | int __lll_private_flag_priv __attribute__ ((unused)); \ |
60 | __lll_private_flag_priv = (private); \ |
61 | ((fl) | FUTEX_PRIVATE_FLAG); \ |
62 | }) |
63 | #else |
64 | # define __lll_private_flag(fl, private) \ |
65 | (((fl) | FUTEX_PRIVATE_FLAG) ^ (private)) |
66 | #endif |
67 | |
68 | #define lll_futex_syscall(nargs, futexp, op, ...) \ |
69 | ({ \ |
70 | INTERNAL_SYSCALL_DECL (__err); \ |
71 | long int __ret = INTERNAL_SYSCALL (futex, __err, nargs, futexp, op, \ |
72 | __VA_ARGS__); \ |
73 | (__glibc_unlikely (INTERNAL_SYSCALL_ERROR_P (__ret, __err)) \ |
74 | ? -INTERNAL_SYSCALL_ERRNO (__ret, __err) : 0); \ |
75 | }) |
76 | |
77 | #define lll_futex_wait(futexp, val, private) \ |
78 | lll_futex_timed_wait (futexp, val, NULL, private) |
79 | |
80 | #define lll_futex_timed_wait(futexp, val, timeout, private) \ |
81 | lll_futex_syscall (4, futexp, \ |
82 | __lll_private_flag (FUTEX_WAIT, private), \ |
83 | val, timeout) |
84 | |
85 | /* Verify whether the supplied clockid is supported by |
86 | lll_futex_clock_wait_bitset. */ |
87 | #define lll_futex_supported_clockid(clockid) \ |
88 | ((clockid) == CLOCK_REALTIME || (clockid) == CLOCK_MONOTONIC) |
89 | |
90 | /* The kernel currently only supports CLOCK_MONOTONIC or |
91 | CLOCK_REALTIME timeouts for FUTEX_WAIT_BITSET. We could attempt to |
92 | convert others here but currently do not. */ |
93 | #define lll_futex_clock_wait_bitset(futexp, val, clockid, timeout, private) \ |
94 | ({ \ |
95 | long int __ret; \ |
96 | if (lll_futex_supported_clockid (clockid)) \ |
97 | { \ |
98 | const unsigned int clockbit = \ |
99 | (clockid == CLOCK_REALTIME) ? FUTEX_CLOCK_REALTIME : 0; \ |
100 | const int op = \ |
101 | __lll_private_flag (FUTEX_WAIT_BITSET | clockbit, private); \ |
102 | \ |
103 | __ret = lll_futex_syscall (6, futexp, op, val, \ |
104 | timeout, NULL /* Unused. */, \ |
105 | FUTEX_BITSET_MATCH_ANY); \ |
106 | } \ |
107 | else \ |
108 | __ret = -EINVAL; \ |
109 | __ret; \ |
110 | }) |
111 | |
112 | #define lll_futex_wake(futexp, nr, private) \ |
113 | lll_futex_syscall (4, futexp, \ |
114 | __lll_private_flag (FUTEX_WAKE, private), nr, 0) |
115 | |
116 | /* Returns non-zero if error happened, zero if success. */ |
117 | #define lll_futex_requeue(futexp, nr_wake, nr_move, mutex, val, private) \ |
118 | lll_futex_syscall (6, futexp, \ |
119 | __lll_private_flag (FUTEX_CMP_REQUEUE, private), \ |
120 | nr_wake, nr_move, mutex, val) |
121 | |
122 | /* Returns non-zero if error happened, zero if success. */ |
123 | #define lll_futex_wake_unlock(futexp, nr_wake, nr_wake2, futexp2, private) \ |
124 | lll_futex_syscall (6, futexp, \ |
125 | __lll_private_flag (FUTEX_WAKE_OP, private), \ |
126 | nr_wake, nr_wake2, futexp2, \ |
127 | FUTEX_OP_CLEAR_WAKE_IF_GT_ONE) |
128 | |
129 | /* Priority Inheritance support. */ |
130 | #define lll_futex_wait_requeue_pi(futexp, val, mutex, private) \ |
131 | lll_futex_timed_wait_requeue_pi (futexp, val, NULL, 0, mutex, private) |
132 | |
133 | #define lll_futex_timed_wait_requeue_pi(futexp, val, timeout, clockbit, \ |
134 | mutex, private) \ |
135 | lll_futex_syscall (5, futexp, \ |
136 | __lll_private_flag (FUTEX_WAIT_REQUEUE_PI \ |
137 | | (clockbit), private), \ |
138 | val, timeout, mutex) |
139 | |
140 | |
141 | #define lll_futex_cmp_requeue_pi(futexp, nr_wake, nr_move, mutex, \ |
142 | val, private) \ |
143 | lll_futex_syscall (6, futexp, \ |
144 | __lll_private_flag (FUTEX_CMP_REQUEUE_PI, \ |
145 | private), \ |
146 | nr_wake, nr_move, mutex, val) |
147 | |
148 | |
149 | /* Cancellable futex macros. */ |
150 | #define lll_futex_wait_cancel(futexp, val, private) \ |
151 | ({ \ |
152 | int __oldtype = CANCEL_ASYNC (); \ |
153 | long int __err = lll_futex_wait (futexp, val, LLL_SHARED); \ |
154 | CANCEL_RESET (__oldtype); \ |
155 | __err; \ |
156 | }) |
157 | |
158 | #define lll_futex_timed_wait_cancel(futexp, val, timeout, private) \ |
159 | ({ \ |
160 | int __oldtype = CANCEL_ASYNC (); \ |
161 | long int __err = lll_futex_timed_wait (futexp, val, timeout, private); \ |
162 | CANCEL_RESET (__oldtype); \ |
163 | __err; \ |
164 | }) |
165 | |
166 | #endif /* !__ASSEMBLER__ */ |
167 | |
168 | #endif /* lowlevellock-futex.h */ |
169 | |