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1 | // SPDX-FileCopyrightText: 1991-1994 by Xerox Corporation. All rights reserved. |
2 | // SPDX-FileCopyrightText: 1996-1999 by Silicon Graphics. All rights reserved. | |
3 | // SPDX-FileCopyrightText: 1999-2004 Hewlett-Packard Development Company, L.P. | |
4 | // SPDX-FileCopyrightText: 2009 Mathieu Desnoyers <mathieu.desnoyers@efficios.com> | |
5 | // SPDX-FileCopyrightText: 2010 Paul E. McKenney, IBM Corporation | |
6 | // | |
7 | // SPDX-License-Identifier: LicenseRef-Boehm-GC | |
8 | ||
6aca0125 JW |
9 | #ifndef _URCU_ARCH_UATOMIC_ARM_H |
10 | #define _URCU_ARCH_UATOMIC_ARM_H | |
fdbddd0b | 11 | |
67ecffc0 | 12 | /* |
6aca0125 | 13 | * Atomics for ARM. This approach is usable on kernels back to 2.6.15. |
fdbddd0b | 14 | * |
fdbddd0b PM |
15 | * Code inspired from libuatomic_ops-1.2, inherited in part from the |
16 | * Boehm-Demers-Weiser conservative garbage collector. | |
17 | */ | |
18 | ||
19 | #include <urcu/compiler.h> | |
20 | #include <urcu/system.h> | |
c278ffc7 | 21 | #include <urcu/arch.h> |
fdbddd0b PM |
22 | |
23 | #ifdef __cplusplus | |
24 | extern "C" { | |
67ecffc0 | 25 | #endif |
fdbddd0b PM |
26 | |
27 | /* xchg */ | |
c278ffc7 MD |
28 | |
29 | /* | |
30 | * Based on [1], __sync_lock_test_and_set() is not a full barrier, but | |
31 | * instead only an acquire barrier. Given that uatomic_xchg() acts as | |
32 | * both release and acquire barriers, we therefore need to have our own | |
33 | * release barrier before this operation. | |
34 | * | |
35 | * [1] https://gcc.gnu.org/onlinedocs/gcc-4.1.0/gcc/Atomic-Builtins.html | |
36 | */ | |
37 | #define uatomic_xchg(addr, v) \ | |
38 | ({ \ | |
39 | cmm_smp_mb(); \ | |
40 | __sync_lock_test_and_set(addr, v); \ | |
41 | }) | |
fdbddd0b | 42 | |
67ecffc0 | 43 | #ifdef __cplusplus |
fdbddd0b PM |
44 | } |
45 | #endif | |
46 | ||
a2e7bf9c | 47 | #include <urcu/uatomic/generic.h> |
fdbddd0b | 48 | |
6aca0125 | 49 | #endif /* _URCU_ARCH_UATOMIC_ARM_H */ |