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Orion Hodson563ada22018-09-04 11:28:31 +01001/*
2 * Copyright (C) 2018 The Android Open Source Project
3 *
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
7 *
8 * http://www.apache.org/licenses/LICENSE-2.0
9 *
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.
15 */
16
17#include "membarrier.h"
18
19#include <errno.h>
Wang Han3f43b932019-09-14 16:47:47 +000020#include <stdio.h>
Orion Hodson563ada22018-09-04 11:28:31 +010021
David Sehr10db8fe2018-07-18 11:01:20 -070022#if !defined(_WIN32)
Orion Hodson563ada22018-09-04 11:28:31 +010023#include <sys/syscall.h>
Lokesh Gidra58520df2020-05-13 17:08:43 +000024#include <sys/utsname.h>
Orion Hodson563ada22018-09-04 11:28:31 +010025#include <unistd.h>
David Sehr10db8fe2018-07-18 11:01:20 -070026#endif
Orion Hodson563ada22018-09-04 11:28:31 +010027#include "macros.h"
28
29#if defined(__BIONIC__)
30
31#include <atomic>
Orion Hodson563ada22018-09-04 11:28:31 +010032#include <linux/membarrier.h>
33
34#define CHECK_MEMBARRIER_CMD(art_value, membarrier_value) \
Andreas Gampe584771b2018-10-18 13:22:23 -070035 static_assert(static_cast<int>(art_value) == (membarrier_value), "Bad value for " # art_value)
Orion Hodson563ada22018-09-04 11:28:31 +010036CHECK_MEMBARRIER_CMD(art::MembarrierCommand::kQuery, MEMBARRIER_CMD_QUERY);
37CHECK_MEMBARRIER_CMD(art::MembarrierCommand::kGlobal, MEMBARRIER_CMD_SHARED);
38CHECK_MEMBARRIER_CMD(art::MembarrierCommand::kPrivateExpedited, MEMBARRIER_CMD_PRIVATE_EXPEDITED);
39CHECK_MEMBARRIER_CMD(art::MembarrierCommand::kRegisterPrivateExpedited,
40 MEMBARRIER_CMD_REGISTER_PRIVATE_EXPEDITED);
41CHECK_MEMBARRIER_CMD(art::MembarrierCommand::kPrivateExpedited, MEMBARRIER_CMD_PRIVATE_EXPEDITED);
42#undef CHECK_MEMBARRIER_CMD
43
44#endif // __BIONIC
45
46namespace art {
47
Vladimir Markoc2167442023-01-17 14:34:08 +000048#if defined(__NR_membarrier)
Zhen Zhang6c2275d2023-01-18 20:56:22 +000049
Vladimir Markoc2bdabb2023-07-11 14:35:19 +020050static bool IsMemBarrierSupported() {
Wang Han3f43b932019-09-14 16:47:47 +000051 // Check kernel version supports membarrier(2).
Vladimir Markoc280a8a2023-07-31 13:33:12 +020052 // MEMBARRIER_CMD_QUERY is supported since Linux 4.3.
53 // MEMBARRIER_CMD_PRIVATE_EXPEDITED is supported since Linux 4.14.
54 // MEMBARRIER_CMD_PRIVATE_EXPEDITED_SYNC_CORE is supported since Linux 4.16.
55 // Lowest Linux version useful for ART is 4.14.
Lokesh Gidra58520df2020-05-13 17:08:43 +000056 static constexpr int kRequiredMajor = 4;
Vladimir Markoc280a8a2023-07-31 13:33:12 +020057 static constexpr int kRequiredMinor = 14;
Lokesh Gidra58520df2020-05-13 17:08:43 +000058 struct utsname uts;
59 int major, minor;
60 if (uname(&uts) != 0 ||
61 strcmp(uts.sysname, "Linux") != 0 ||
62 sscanf(uts.release, "%d.%d", &major, &minor) != 2 ||
63 (major < kRequiredMajor || (major == kRequiredMajor && minor < kRequiredMinor))) {
Vladimir Markoc2bdabb2023-07-11 14:35:19 +020064 return false;
Wang Han3f43b932019-09-14 16:47:47 +000065 }
Orion Hodson563ada22018-09-04 11:28:31 +010066#if defined(__BIONIC__)
67 // Avoid calling membarrier on older Android versions where membarrier may be barred by secomp
68 // causing the current process to be killed. The probing here could be considered expensive so
69 // endeavour not to repeat too often.
Vladimir Markoc2bdabb2023-07-11 14:35:19 +020070 int api_level = android_get_device_api_level();
Orion Hodson563ada22018-09-04 11:28:31 +010071 if (api_level < __ANDROID_API_Q__) {
Vladimir Markoc2bdabb2023-07-11 14:35:19 +020072 return false;
73 }
74#endif // __BIONIC__
75 return true;
76}
77
78int membarrier(MembarrierCommand command) {
79 static const bool membarrier_supported = IsMemBarrierSupported();
80 if (UNLIKELY(!membarrier_supported)) {
Orion Hodson563ada22018-09-04 11:28:31 +010081 errno = ENOSYS;
82 return -1;
83 }
Orion Hodson563ada22018-09-04 11:28:31 +010084 return syscall(__NR_membarrier, static_cast<int>(command), 0);
Zhen Zhang6c2275d2023-01-18 20:56:22 +000085}
86
Orion Hodson563ada22018-09-04 11:28:31 +010087#else // __NR_membarrier
Zhen Zhang6c2275d2023-01-18 20:56:22 +000088
Stefano Cianciulli78f3c722023-05-16 10:32:54 +000089int membarrier([[maybe_unused]] MembarrierCommand command) {
Orion Hodson563ada22018-09-04 11:28:31 +010090 // In principle this could be supported on linux, but Android's prebuilt glibc does not include
Vladimir Markoc2bdabb2023-07-11 14:35:19 +020091 // the system call number definitions (b/111199492).
Orion Hodson563ada22018-09-04 11:28:31 +010092 errno = ENOSYS;
93 return -1;
Vladimir Markoc2167442023-01-17 14:34:08 +000094}
Orion Hodson563ada22018-09-04 11:28:31 +010095
Zhen Zhang6c2275d2023-01-18 20:56:22 +000096#endif // __NR_membarrier
97
Orion Hodson563ada22018-09-04 11:28:31 +010098} // namespace art