1 /* $NetBSD: barrier.h,v 1.21 2023/02/25 12:23:36 riastradh 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 Taylor R. Campbell. 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 #ifndef _ASM_BARRIER_H_ 33 #define _ASM_BARRIER_H_ 34 35 #include <sys/atomic.h> 36 37 #include <linux/compiler.h> 38 39 #ifdef _KERNEL_OPT 40 #include "opt_multiprocessor.h" 41 #else 42 #define MULTIPROCESSOR 1 /* safer to assume multiprocessor */ 43 #endif 44 45 /* 46 * I/O memory barriers. drm uses these to order memory operations on 47 * normal or write-combining/prefetchable, or uncacheable I/O 48 * operations, for coordination between the CPU and I/O devices. 49 * 50 * In NetBSD, this is normally done with bus_space_barrier, but Linux 51 * doesn't pass around the bus space tag and handle needed for that. 52 */ 53 #if defined(__aarch64__) 54 #include <arm/cpufunc.h> 55 #define mb() dsb(sy) 56 #define wmb() dsb(st) 57 #define rmb() dsb(ld) 58 #elif defined(__arm__) 59 #include <arm/cpufunc.h> 60 #define mb() dsb() 61 #define wmb() mb() 62 #define rmb() mb() 63 #elif defined(__i386__) || defined(__x86_64__) 64 #include <x86/cpufunc.h> 65 #define mb() x86_mfence() 66 #define wmb() x86_sfence() 67 #define rmb() x86_lfence() 68 #elif defined(__powerpc__) 69 #define mb() __asm __volatile ("eieio" ::: "memory") 70 #define wmb() mb() 71 #define rmb() mb() 72 #elif defined(__sparc__) || defined(__sparc64__) 73 #ifdef __sparc64__ 74 #define mb() __asm __volatile ("membar #MemIssue" ::: "memory") 75 #else 76 #define mb() membar_sync() /* ldstub */ 77 #endif 78 #define wmb() mb() /* XXX could maybe be __insn_barrier in TSO */ 79 #define rmb() mb() /* XXX could maybe be __insn_barrier in TSO */ 80 #elif defined(__mips__) 81 #include <mips/locore.h> 82 #define mb() wbflush() 83 #define wmb() mb() 84 #define rmb() mb() 85 #elif defined(__alpha__) 86 #include <machine/alpha_cpu.h> 87 #define mb() alpha_mb() 88 #define wmb() alpha_wmb() 89 #define rmb() mb() 90 #else 91 #error Missing Linux memory-mapped I/O barriers for this architecture. 92 #endif 93 94 /* 95 * MP memory barriers. drm uses these to order memory operations on 96 * normal memory for coordination between CPUs. Aliases for NetBSD's 97 * membar_*. 98 */ 99 #ifdef MULTIPROCESSOR 100 # define smp_mb membar_sync 101 # define smp_wmb membar_producer 102 # define smp_rmb membar_consumer 103 # define smp_mb__before_atomic membar_release 104 # define smp_mb__after_atomic membar_acquire 105 #else 106 # define smp_mb() __insn_barrier() 107 # define smp_wmb() __insn_barrier() 108 # define smp_rmb() __insn_barrier() 109 # define smp_mb__before_atomic() __nothing 110 # define smp_mb__after_atomic() __nothing 111 #endif 112 113 #endif /* _ASM_BARRIER_H_ */ 114