Fix alignment issue with 64-bit atomics on 32 bit machines

1 files changed, 61 insertions, 0 deletions

diff --git a/pkg/tcpip/aligned.go b/pkg/tcpip/aligned.go
new file mode 100644
index 000000000..ea22c101f
--- /dev/null
+++ b/pkg/tcpip/aligned.go
@@ -0,0 +1,61 @@
+// Copyright 2021 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.
+
+// +build !arm,!386
+
+package tcpip
+
+import "sync/atomic"
+
+// AlignedAtomicInt64 is an atomic int64 that is guaranteed to be 64-bit
+// aligned, even on 32-bit systems. On 64-bit machines, it's just a regular
+// int64.
+//
+// See aligned_unsafe.go in this directory for justification.
+type AlignedAtomicInt64 struct {
+	value int64
+}
+
+func (aa *AlignedAtomicInt64) Load() int64 {
+	return atomic.LoadInt64(&aa.value)
+}
+
+func (aa *AlignedAtomicInt64) Store(v int64) {
+	atomic.StoreInt64(&aa.value, v)
+}
+
+func (aa *AlignedAtomicInt64) Add(v int64) int64 {
+	return atomic.AddInt64(&aa.value, v)
+}
+
+// AlignedAtomicUint64 is an atomic uint64 that is guaranteed to be 64-bit
+// aligned, even on 32-bit systems. On 64-bit machines, it's just a regular
+// uint64.
+//
+// See aligned_unsafe.go in this directory for justification.
+type AlignedAtomicUint64 struct {
+	value uint64
+}
+
+func (aa *AlignedAtomicUint64) Load() uint64 {
+	return atomic.LoadUint64(&aa.value)
+}
+
+func (aa *AlignedAtomicUint64) Store(v uint64) {
+	atomic.StoreUint64(&aa.value, v)
+}
+
+func (aa *AlignedAtomicUint64) Add(v uint64) uint64 {
+	return atomic.AddUint64(&aa.value, v)
+}