blob: 490dbf3fa0829733a90442c1078add5a8a996a18 [file] [log] [blame]
/*
* Copyright (C) 2018 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#include "membarrier.h"
#include <errno.h>
#include <sys/syscall.h>
#include <unistd.h>
#include "macros.h"
#if defined(__BIONIC__)
#include <atomic>
#include <android/get_device_api_level.h>
#include <linux/membarrier.h>
#define CHECK_MEMBARRIER_CMD(art_value, membarrier_value) \
static_assert(static_cast<int>(art_value) == membarrier_value, "Bad value for " # art_value)
CHECK_MEMBARRIER_CMD(art::MembarrierCommand::kQuery, MEMBARRIER_CMD_QUERY);
CHECK_MEMBARRIER_CMD(art::MembarrierCommand::kGlobal, MEMBARRIER_CMD_SHARED);
CHECK_MEMBARRIER_CMD(art::MembarrierCommand::kPrivateExpedited, MEMBARRIER_CMD_PRIVATE_EXPEDITED);
CHECK_MEMBARRIER_CMD(art::MembarrierCommand::kRegisterPrivateExpedited,
MEMBARRIER_CMD_REGISTER_PRIVATE_EXPEDITED);
CHECK_MEMBARRIER_CMD(art::MembarrierCommand::kPrivateExpedited, MEMBARRIER_CMD_PRIVATE_EXPEDITED);
#undef CHECK_MEMBARRIER_CMD
#endif // __BIONIC
namespace art {
#if defined(__NR_membarrier)
int membarrier(MembarrierCommand command) {
#if defined(__BIONIC__)
// Avoid calling membarrier on older Android versions where membarrier may be barred by secomp
// causing the current process to be killed. The probing here could be considered expensive so
// endeavour not to repeat too often.
static int api_level = android_get_device_api_level();
if (api_level < __ANDROID_API_Q__) {
errno = ENOSYS;
return -1;
}
#endif // __BIONIC__
return syscall(__NR_membarrier, static_cast<int>(command), 0);
}
#else // __NR_membarrier
int membarrier(MembarrierCommand command ATTRIBUTE_UNUSED) {
// In principle this could be supported on linux, but Android's prebuilt glibc does not include
// the system call number defintions (b/111199492).
errno = ENOSYS;
return -1;
}
#endif // __NR_membarrier
} // namespace art