1/* $NetBSD: sync_bool_compare_and_swap_1.S,v 1.1 2013/11/08 22:42:52 matt Exp $ */ 2 3/*- 4 * Copyright (c) 2013 The NetBSD Foundation, Inc. 5 * All rights reserved. 6 * 7 * This code is derived from software contributed to The NetBSD Foundation 8 * by Matt Thomas <matt@3am-software.com> 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#include "atomic_op_asm.h" 33 34#if defined(_ARM_ARCH_6) 35/* 36 * ARMv6 has load-exclusive/store-exclusive which works for both user 37 * and kernel. 38 */ 39ENTRY_NP(__sync_bool_compare_and_swap_1) 40 mov ip, r0 /* we need r0 for return value */ 41 mov r0, #0 /* assume no match */ 421: 43 ldrexb r3, [ip] /* load old value */ 44 cmp r3, r1 /* compare? */ 45#ifdef __thumb__ 46 bne 2f 47#else 48 RETc(ne) /* return if different */ 49#endif 50 strexb r0, r2, [ip] /* store new value */ 51 cmp r0, #0 /* succeed? */ 52 bne 1b /* nope, try again. */ 53 mov r0, #1 /* it was a success */ 54#ifdef _ARM_ARCH_7 55 dsb /* data synchronization barrier */ 56#else 57 mcr p15, 0, r3, c7, c10, 4 /* data synchronization barrier */ 58#endif 592: RET /* return. */ 60END(__sync_bool_compare_and_swap_1) 61 62#endif /* _ARM_ARCH_6 */ 63