1 files changed, 95 insertions, 0 deletions
diff --git a/src/tracing/ipc/memfd.cc b/src/tracing/ipc/memfd.cc
new file mode 100644
index 000000000..64025bf41
--- /dev/null
+++ b/src/tracing/ipc/memfd.cc
@@ -0,0 +1,95 @@
+/*
+ * Copyright (C) 2020 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 "src/tracing/ipc/memfd.h"
+
+#include <errno.h>
+
+#define PERFETTO_MEMFD_ENABLED()             \
+  PERFETTO_BUILDFLAG(PERFETTO_OS_ANDROID) || \
+      PERFETTO_BUILDFLAG(PERFETTO_OS_LINUX)
+
+#if PERFETTO_MEMFD_ENABLED()
+
+#include <stdio.h>
+#include <string.h>
+#include <sys/syscall.h>
+#include <sys/utsname.h>
+#include <unistd.h>
+
+// Some android build bots use a sysroot that doesn't support memfd when
+// compiling for the host, so we redefine it if necessary.
+#if !defined(__NR_memfd_create)
+#if defined(__x86_64__)
+#define __NR_memfd_create 319
+#elif defined(__i386__)
+#define __NR_memfd_create 356
+#elif defined(__aarch64__)
+#define __NR_memfd_create 279
+#elif defined(__arm__)
+#define __NR_memfd_create 385
+#else
+#error "unsupported sysroot without memfd support"
+#endif
+#endif  // !defined(__NR_memfd_create)
+
+namespace perfetto {
+bool HasMemfdSupport() {
+  static bool kSupportsMemfd = [] {
+    // Check kernel version supports memfd_create(). Some older kernels segfault
+    // executing memfd_create() rather than returning ENOSYS (b/116769556).
+    static constexpr int kRequiredMajor = 3;
+    static constexpr int kRequiredMinor = 17;
+    struct utsname uts;
+    int major, minor;
+    if (uname(&uts) == 0 && strcmp(uts.sysname, "Linux") == 0 &&
+        sscanf(uts.release, "%d.%d", &major, &minor) == 2 &&
+        ((major < kRequiredMajor ||
+          (major == kRequiredMajor && minor < kRequiredMinor)))) {
+      return false;
+    }
+
+    base::ScopedFile fd;
+    fd.reset(static_cast<int>(syscall(__NR_memfd_create, "perfetto_shmem",
+                                      MFD_CLOEXEC | MFD_ALLOW_SEALING)));
+    return !!fd;
+  }();
+  return kSupportsMemfd;
+}
+
+base::ScopedFile CreateMemfd(const char* name, unsigned int flags) {
+  if (!HasMemfdSupport()) {
+    errno = ENOSYS;
+    return base::ScopedFile();
+  }
+  return base::ScopedFile(
+      static_cast<int>(syscall(__NR_memfd_create, name, flags)));
+}
+}  // namespace perfetto
+
+#else  // PERFETTO_MEMFD_ENABLED()
+
+namespace perfetto {
+bool HasMemfdSupport() {
+  return false;
+}
+base::ScopedFile CreateMemfd(const char*, unsigned int) {
+  errno = ENOSYS;
+  return base::ScopedFile();
+}
+}  // namespace perfetto
+
+#endif  // PERFETTO_MEMFD_ENABLED()