67 lines
1.6 KiB
C++
67 lines
1.6 KiB
C++
/*
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* Copyright (c) Facebook, Inc. and its affiliates.
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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#include <folly/portability/SysMembarrier.h>
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#include <mutex>
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#include <folly/Portability.h>
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#include <folly/portability/SysSyscall.h>
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#include <folly/portability/Unistd.h>
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#if FOLLY_X64 && !FOLLY_MOBILE && defined(__linux__)
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#define FOLLY_USE_SYS_MEMBARRIER 1
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#if !defined(__NR_membarrier)
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#define __NR_membarrier 324
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#endif
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#if __has_include(<linux/membarrier.h>)
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#include <linux/membarrier.h> // @manual
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#else
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#define MEMBARRIER_CMD_QUERY 0
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#define MEMBARRIER_CMD_SHARED 1
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#endif
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#endif
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namespace folly {
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namespace detail {
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bool sysMembarrierAvailable() {
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if (!kIsLinux) {
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return false;
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}
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#if FOLLY_USE_SYS_MEMBARRIER
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auto r = syscall(__NR_membarrier, MEMBARRIER_CMD_QUERY, /* flags = */ 0);
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if (r == -1) {
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return false;
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}
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return r & MEMBARRIER_CMD_SHARED;
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#else
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return false;
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#endif
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}
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int sysMembarrier() {
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#if FOLLY_USE_SYS_MEMBARRIER
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return syscall(__NR_membarrier, MEMBARRIER_CMD_SHARED, /* flags = */ 0);
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#else
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return -1;
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#endif
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}
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} // namespace detail
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} // namespace folly
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