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1 | /* Copyright (C) 2010 Free Software Foundation, Inc. |
2 | Contributed by ARM Ltd. | |
3 | ||
4 | This file is part of the GNU OpenMP Library (libgomp). | |
5 | ||
6 | Libgomp is free software; you can redistribute it and/or modify it | |
7 | under the terms of the GNU General Public License as published by | |
8 | the Free Software Foundation; either version 3, or (at your option) | |
9 | any later version. | |
10 | ||
11 | Libgomp is distributed in the hope that it will be useful, but WITHOUT ANY | |
12 | WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS | |
13 | FOR A PARTICULAR PURPOSE. See the GNU General Public License for | |
14 | more details. | |
15 | ||
16 | Under Section 7 of GPL version 3, you are granted additional | |
17 | permissions described in the GCC Runtime Library Exception, version | |
18 | 3.1, as published by the Free Software Foundation. | |
19 | ||
20 | You should have received a copy of the GNU General Public License and | |
21 | a copy of the GCC Runtime Library Exception along with this program; | |
22 | see the files COPYING3 and COPYING.RUNTIME respectively. If not, see | |
23 | <http://www.gnu.org/licenses/>. */ | |
24 | ||
25 | /* Provide target-specific access to the futex system call. */ | |
26 | ||
27 | /* The include file hierachy above us (wait.h) has pushed visibility | |
28 | hidden, this will be applied to prototypes with headers we include | |
29 | with the effect that we cannot link against an external function | |
30 | (syscall). The solution here is to push default visibility, include | |
31 | our required headers then reinstante the original visibility. */ | |
32 | ||
33 | #pragma GCC visibility push(default) | |
34 | ||
35 | #define _GNU_SOURCE | |
36 | #include <unistd.h> | |
37 | #include <sys/syscall.h> | |
38 | ||
39 | #pragma GCC visibility pop | |
40 | ||
41 | static inline void | |
42 | futex_wait (int *addr, int val) | |
43 | { | |
44 | long err = syscall (SYS_futex, addr, gomp_futex_wait, val); | |
45 | if (__builtin_expect (err == -ENOSYS, 0)) | |
46 | { | |
47 | gomp_futex_wait &= ~FUTEX_PRIVATE_FLAG; | |
48 | gomp_futex_wake &= ~FUTEX_PRIVATE_FLAG; | |
49 | syscall (SYS_futex, addr, gomp_futex_wait, val); | |
50 | } | |
51 | } | |
52 | ||
53 | static inline void | |
54 | futex_wake (int *addr, int count) | |
55 | { | |
56 | long err = syscall (SYS_futex, addr, gomp_futex_wake, count); | |
57 | if (__builtin_expect (err == -ENOSYS, 0)) | |
58 | { | |
59 | gomp_futex_wait &= ~FUTEX_PRIVATE_FLAG; | |
60 | gomp_futex_wake &= ~FUTEX_PRIVATE_FLAG; | |
61 | syscall (SYS_futex, addr, gomp_futex_wake, count); | |
62 | } | |
63 | } | |
64 | ||
65 | static inline void | |
66 | cpu_relax (void) | |
67 | { | |
68 | __asm volatile ("" : : : "memory"); | |
69 | } | |
70 | ||
71 | static inline void | |
72 | atomic_write_barrier (void) | |
73 | { | |
74 | __sync_synchronize (); | |
75 | } |