| 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 | |
| 9 | #ifndef _URCU_ARCH_UATOMIC_ARM_H |
| 10 | #define _URCU_ARCH_UATOMIC_ARM_H |
| 11 | |
| 12 | /* |
| 13 | * Atomics for ARM. This approach is usable on kernels back to 2.6.15. |
| 14 | * |
| 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> |
| 21 | #include <urcu/arch.h> |
| 22 | |
| 23 | #ifdef __cplusplus |
| 24 | extern "C" { |
| 25 | #endif |
| 26 | |
| 27 | /* xchg */ |
| 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 | }) |
| 42 | |
| 43 | #ifdef __cplusplus |
| 44 | } |
| 45 | #endif |
| 46 | |
| 47 | #include <urcu/uatomic/generic.h> |
| 48 | |
| 49 | #endif /* _URCU_ARCH_UATOMIC_ARM_H */ |