1 files changed, 49 insertions, 0 deletions
diff --git a/vdso/barrier.h b/vdso/barrier.h
new file mode 100644
index 000000000..edba4afb5
--- /dev/null
+++ b/vdso/barrier.h
@@ -0,0 +1,49 @@
+// Copyright 2018 The gVisor Authors.
+//
+// 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.
+
+#ifndef VDSO_BARRIER_H_
+#define VDSO_BARRIER_H_
+
+namespace vdso {
+
+// Compiler Optimization barrier.
+inline void barrier(void) { __asm__ __volatile__("" ::: "memory"); }
+
+#if __x86_64__
+
+inline void memory_barrier(void) {
+  __asm__ __volatile__("mfence" ::: "memory");
+}
+inline void read_barrier(void) { barrier(); }
+inline void write_barrier(void) { barrier(); }
+
+#elif __aarch64__
+
+inline void memory_barrier(void) {
+  __asm__ __volatile__("dmb ish" ::: "memory");
+}
+inline void read_barrier(void) {
+  __asm__ __volatile__("dmb ishld" ::: "memory");
+}
+inline void write_barrier(void) {
+  __asm__ __volatile__("dmb ishst" ::: "memory");
+}
+
+#else
+#error "unsupported architecture"
+#endif
+
+}  // namespace vdso
+
+#endif  // VDSO_BARRIER_H_