Eric Seckler | 14a22db | 2020-02-03 13:47:08 +0000 | [diff] [blame^] | 1 | /* |
| 2 | * Copyright (C) 2020 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 "src/tracing/ipc/memfd.h" |
| 18 | |
| 19 | #include <errno.h> |
| 20 | |
| 21 | #define PERFETTO_MEMFD_ENABLED() \ |
| 22 | PERFETTO_BUILDFLAG(PERFETTO_OS_ANDROID) || \ |
| 23 | PERFETTO_BUILDFLAG(PERFETTO_OS_LINUX) |
| 24 | |
| 25 | #if PERFETTO_MEMFD_ENABLED() |
| 26 | |
| 27 | #include <stdio.h> |
| 28 | #include <string.h> |
| 29 | #include <sys/syscall.h> |
| 30 | #include <sys/utsname.h> |
| 31 | #include <unistd.h> |
| 32 | |
| 33 | // Some android build bots use a sysroot that doesn't support memfd when |
| 34 | // compiling for the host, so we redefine it if necessary. |
| 35 | #if !defined(__NR_memfd_create) |
| 36 | #if defined(__x86_64__) |
| 37 | #define __NR_memfd_create 319 |
| 38 | #elif defined(__i386__) |
| 39 | #define __NR_memfd_create 356 |
| 40 | #elif defined(__aarch64__) |
| 41 | #define __NR_memfd_create 279 |
| 42 | #elif defined(__arm__) |
| 43 | #define __NR_memfd_create 385 |
| 44 | #else |
| 45 | #error "unsupported sysroot without memfd support" |
| 46 | #endif |
| 47 | #endif // !defined(__NR_memfd_create) |
| 48 | |
| 49 | namespace perfetto { |
| 50 | bool HasMemfdSupport() { |
| 51 | static bool kSupportsMemfd = [] { |
| 52 | // Check kernel version supports memfd_create(). Some older kernels segfault |
| 53 | // executing memfd_create() rather than returning ENOSYS (b/116769556). |
| 54 | static constexpr int kRequiredMajor = 3; |
| 55 | static constexpr int kRequiredMinor = 17; |
| 56 | struct utsname uts; |
| 57 | int major, minor; |
| 58 | if (uname(&uts) == 0 && strcmp(uts.sysname, "Linux") == 0 && |
| 59 | sscanf(uts.release, "%d.%d", &major, &minor) == 2 && |
| 60 | ((major < kRequiredMajor || |
| 61 | (major == kRequiredMajor && minor < kRequiredMinor)))) { |
| 62 | return false; |
| 63 | } |
| 64 | |
| 65 | base::ScopedFile fd; |
| 66 | fd.reset(static_cast<int>(syscall(__NR_memfd_create, "perfetto_shmem", |
| 67 | MFD_CLOEXEC | MFD_ALLOW_SEALING))); |
| 68 | return !!fd; |
| 69 | }(); |
| 70 | return kSupportsMemfd; |
| 71 | } |
| 72 | |
| 73 | base::ScopedFile CreateMemfd(const char* name, unsigned int flags) { |
| 74 | if (!HasMemfdSupport()) { |
| 75 | errno = ENOSYS; |
| 76 | return base::ScopedFile(); |
| 77 | } |
| 78 | return base::ScopedFile( |
| 79 | static_cast<int>(syscall(__NR_memfd_create, name, flags))); |
| 80 | } |
| 81 | } // namespace perfetto |
| 82 | |
| 83 | #else // PERFETTO_MEMFD_ENABLED() |
| 84 | |
| 85 | namespace perfetto { |
| 86 | bool HasMemfdSupport() { |
| 87 | return false; |
| 88 | } |
| 89 | base::ScopedFile CreateMemfd(const char*, unsigned int) { |
| 90 | errno = ENOSYS; |
| 91 | return base::ScopedFile(); |
| 92 | } |
| 93 | } // namespace perfetto |
| 94 | |
| 95 | #endif // PERFETTO_MEMFD_ENABLED() |