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88 lines
2.8 KiB
88 lines
2.8 KiB
/*
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* Copyright (C) 2018 The Android Open Source Project
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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 "membarrier.h"
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#include <errno.h>
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#include <stdio.h>
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#if !defined(_WIN32)
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#include <sys/syscall.h>
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#include <sys/utsname.h>
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#include <unistd.h>
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#endif
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#include "macros.h"
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#if defined(__BIONIC__)
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#include <atomic>
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#include <linux/membarrier.h>
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#define CHECK_MEMBARRIER_CMD(art_value, membarrier_value) \
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static_assert(static_cast<int>(art_value) == (membarrier_value), "Bad value for " # art_value)
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CHECK_MEMBARRIER_CMD(art::MembarrierCommand::kQuery, MEMBARRIER_CMD_QUERY);
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CHECK_MEMBARRIER_CMD(art::MembarrierCommand::kGlobal, MEMBARRIER_CMD_SHARED);
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CHECK_MEMBARRIER_CMD(art::MembarrierCommand::kPrivateExpedited, MEMBARRIER_CMD_PRIVATE_EXPEDITED);
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CHECK_MEMBARRIER_CMD(art::MembarrierCommand::kRegisterPrivateExpedited,
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MEMBARRIER_CMD_REGISTER_PRIVATE_EXPEDITED);
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CHECK_MEMBARRIER_CMD(art::MembarrierCommand::kPrivateExpedited, MEMBARRIER_CMD_PRIVATE_EXPEDITED);
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#undef CHECK_MEMBARRIER_CMD
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#endif // __BIONIC
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namespace art {
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#if defined(__NR_membarrier)
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int membarrier(MembarrierCommand command) {
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// Check kernel version supports membarrier(2).
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static constexpr int kRequiredMajor = 4;
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static constexpr int kRequiredMinor = 16;
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struct utsname uts;
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int major, minor;
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if (uname(&uts) != 0 ||
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strcmp(uts.sysname, "Linux") != 0 ||
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sscanf(uts.release, "%d.%d", &major, &minor) != 2 ||
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(major < kRequiredMajor || (major == kRequiredMajor && minor < kRequiredMinor))) {
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errno = ENOSYS;
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return -1;
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}
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#if defined(__BIONIC__)
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// Avoid calling membarrier on older Android versions where membarrier may be barred by secomp
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// causing the current process to be killed. The probing here could be considered expensive so
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// endeavour not to repeat too often.
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static int api_level = android_get_device_api_level();
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if (api_level < __ANDROID_API_Q__) {
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errno = ENOSYS;
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return -1;
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}
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#endif // __BIONIC__
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return syscall(__NR_membarrier, static_cast<int>(command), 0);
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}
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#else // __NR_membarrier
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int membarrier(MembarrierCommand command ATTRIBUTE_UNUSED) {
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// In principle this could be supported on linux, but Android's prebuilt glibc does not include
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// the system call number defintions (b/111199492).
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errno = ENOSYS;
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return -1;
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}
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#endif // __NR_membarrier
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} // namespace art
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