2 * Copyright 2017 Facebook, Inc.
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
8 * http://www.apache.org/licenses/LICENSE-2.0
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
17 #include "SysMembarrier.h"
21 #include <folly/Portability.h>
22 #include <folly/portability/SysSyscall.h>
23 #include <folly/portability/Unistd.h>
25 #if FOLLY_X64 && !FOLLY_MOBILE && defined(__linux__)
26 #define FOLLY_USE_SYS_MEMBARRIER 1
27 #if !defined(__NR_membarrier)
28 #define __NR_membarrier 324
29 #define MEMBARRIER_CMD_QUERY 0
30 #define MEMBARRIER_CMD_SHARED 1
31 #elif FOLLY_HAVE_LINUX_MEMBARRIER_H
32 #include <linux/membarrier.h> // @manual
39 bool sysMembarrierAvailable() {
44 #if FOLLY_USE_SYS_MEMBARRIER
45 auto r = syscall(__NR_membarrier, MEMBARRIER_CMD_QUERY, /* flags = */ 0);
50 return r & MEMBARRIER_CMD_SHARED;
57 #if FOLLY_USE_SYS_MEMBARRIER
58 return syscall(__NR_membarrier, MEMBARRIER_CMD_SHARED, /* flags = */ 0);