1/* $NetBSD: atomic_cas_8.S,v 1.9 2021/07/28 07:32:20 skrll 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/* 37 * ARMv6 has load-exclusive/store-exclusive which works for both user 38 * and kernel. 39 */ 40ENTRY_NP(_atomic_cas_8) 41 mov ip, r0 /* we need r0 for return value */ 421: 43 ldrexb r0, [ip] /* load old value */ 44 cmp r0, r1 /* compare? */ 45#ifdef __thumb__ 46 bne 2f 47#else 48 RETc(ne) /* return if different */ 49#endif 50 strexb r3, r2, [ip] /* store new value */ 51 cmp r3, #0 /* succeed? */ 52 bne 1b /* nope, try again. */ 532: RET /* return. */ 54END(_atomic_cas_8) 55 56ATOMIC_OP_ALIAS(atomic_cas_8,_atomic_cas_8) 57STRONG_ALIAS(_atomic_cas_char,_atomic_cas_8) 58STRONG_ALIAS(_atomic_cas_uchar,_atomic_cas_8) 59 60ENTRY_NP(__sync_val_compare_and_swap_1) 61 push {r4, lr} 62 DMB 63 bl _atomic_cas_8 64 DMB 65 pop {r4, pc} 66END(__sync_val_compare_and_swap_1) 67 68#endif /* _ARM_ARCH_6 */ 69