1/* $NetBSD: membar_ops.S,v 1.13 2022/04/21 12:06:31 riastradh Exp $ */ 2 3/*- 4 * Copyright (c) 2006, 2007 The NetBSD Foundation, Inc. 5 * All rights reserved. 6 * 7 * This code is derived from software contributed to The NetBSD Foundation 8 * by Jason R. Thorpe, and by Andrew Doran. 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 .text 35 .set noreorder 36 37LEAF(_membar_sync) 38 j ra 39 BDSYNC 40END(_membar_sync) 41ATOMIC_OP_ALIAS(membar_sync,_membar_sync) 42 43STRONG_ALIAS(_membar_enter,_membar_sync) 44ATOMIC_OP_ALIAS(membar_enter,_membar_sync) 45 46#ifdef __OCTEON__ 47 48/* 49 * cnMIPS guarantees load-before-load/store ordering without any 50 * barriers. So the only barriers we need are store-before-load (sync) 51 * and store-before-store (syncw, i.e., sync 4). See Table 2-32 52 * `Execution Ordering Rules' on p. 104 of Cavium OCTEON III CN78XX 53 * Hardware Reference Manual, CN78XX-HM-0.99E, September 2014: 54 * 55 * First Operation DLD [load instruction to a physical 56 * address that is L2/DRAM] 57 * Second Operation Any 58 * Execution Ordering Comments 59 * 60 * The second operation cannot appear to execute before 61 * the first (DLD) operation, regardless of the presence 62 * or absence of SYNC* instructions. 63 * 64 * Note: I'm not sure if this applies to earlier cnMIPS -- can't find 65 * it in the Cavium Networks OCTEON Plus CN50XX Hardware Reference 66 * Manual CN50XX-HM-0.99E, July 2008. Experimentally, on an erlite3 67 * (Cavium Octeon CN5020-500), I can easily detect reordering of 68 * store-before-store and store-before-load, but I haven't been able to 69 * detect any reordering of load-before-load or load-before-store. 70 * 71 * Note: On early cnMIPS (CN3xxx), there is an erratum which sometimes 72 * requires issuing two syncw's in a row. I don't know the details -- 73 * don't have documentation -- and in Linux it is only used for I/O 74 * purposes. 75 * 76 * Currently we don't build kernels that work on both Octeon and 77 * non-Octeon MIPS CPUs, so none of this is done with binary patching. 78 * For userlands we could use a separate shared library on Octeon with 79 * ld.so.conf to override the symbols with cheaper definitions, but we 80 * don't do that now. 81 */ 82 83LEAF(_membar_acquire) 84 j ra 85 nop 86END(_membar_acquire) 87ATOMIC_OP_ALIAS(membar_acquire,_membar_acquire) 88 89STRONG_ALIAS(_membar_consumer,_membar_acquire) 90ATOMIC_OP_ALIAS(membar_consumer,_membar_acquire) 91 92LEAF(_membar_release) 93 j ra 94 syncw 95END(_membar_release) 96ATOMIC_OP_ALIAS(membar_release,_membar_release) 97 98STRONG_ALIAS(_membar_exit,_membar_release) 99ATOMIC_OP_ALIAS(membar_exit,_membar_release) 100 101STRONG_ALIAS(_membar_producer,_membar_release) 102ATOMIC_OP_ALIAS(membar_producer,_membar_release) 103 104#else /* !__OCTEON__ */ 105 106STRONG_ALIAS(_membar_acquire,_membar_sync) 107ATOMIC_OP_ALIAS(membar_acquire,_membar_sync) 108STRONG_ALIAS(_membar_release,_membar_sync) 109ATOMIC_OP_ALIAS(membar_release,_membar_sync) 110STRONG_ALIAS(_membar_exit,_membar_sync) 111ATOMIC_OP_ALIAS(membar_exit,_membar_sync) 112STRONG_ALIAS(_membar_consumer,_membar_sync) 113ATOMIC_OP_ALIAS(membar_consumer,_membar_sync) 114STRONG_ALIAS(_membar_producer,_membar_sync) 115ATOMIC_OP_ALIAS(membar_producer,_membar_sync) 116 117#endif 118