From 4c9340fcbf0cb10c230925e24f082478f7c458a0 Mon Sep 17 00:00:00 2001
From: Kevin Krakauer <krakauer@google.com>
Date: Thu, 18 Mar 2021 15:38:13 -0700
Subject: [PATCH 1/8] Fix alignment issue with 64-bit atomics on 32 bit
 machines

---
 pkg/tcpip/BUILD             |  2 +
 pkg/tcpip/aligned.go        | 61 ++++++++++++++++++++++++++++
 pkg/tcpip/aligned_unsafe.go | 80 +++++++++++++++++++++++++++++++++++++
 pkg/tcpip/socketops.go      |  8 ++--
 pkg/tcpip/tcpip.go          |  4 +-
 5 files changed, 149 insertions(+), 6 deletions(-)
 create mode 100644 pkg/tcpip/aligned.go
 create mode 100644 pkg/tcpip/aligned_unsafe.go

diff --git a/pkg/tcpip/BUILD b/pkg/tcpip/BUILD
index e96ba50ae..5237eba76 100644
--- a/pkg/tcpip/BUILD
+++ b/pkg/tcpip/BUILD
@@ -19,6 +19,8 @@ go_template_instance(
 go_library(
     name = "tcpip",
     srcs = [
+        "aligned.go",
+        "aligned_unsafe.go",
         "errors.go",
         "sock_err_list.go",
         "socketops.go",
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)
+}
diff --git a/pkg/tcpip/aligned_unsafe.go b/pkg/tcpip/aligned_unsafe.go
new file mode 100644
index 000000000..35e869453
--- /dev/null
+++ b/pkg/tcpip/aligned_unsafe.go
@@ -0,0 +1,80 @@
+// 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"
+	"unsafe"
+)
+
+// AlignedAtomicInt64 is an atomic int64 that is guaranteed to be 64-bit
+// aligned, even on 32-bit systems.
+//
+// Per https://golang.org/pkg/sync/atomic/#pkg-note-BUG:
+//
+// "On ARM, 386, and 32-bit MIPS, it is the caller's responsibility to arrange
+// for 64-bit alignment of 64-bit words accessed atomically. The first word in
+// a variable or in an allocated struct, array, or slice can be relied upon to
+// be 64-bit aligned."
+type AlignedAtomicInt64 struct {
+	value [15]byte
+}
+
+func (aa *AlignedAtomicInt64) ptr() *int64 {
+	return (*int64)(unsafe.Pointer((uintptr(unsafe.Pointer(&aa.value)) + 7) &^ 7))
+}
+
+func (aa *AlignedAtomicInt64) Load() int64 {
+	return atomic.LoadInt64(aa.ptr())
+}
+
+func (aa *AlignedAtomicInt64) Store(v int64) {
+	atomic.StoreInt64(aa.ptr(), v)
+}
+
+func (aa *AlignedAtomicInt64) Add(v int64) int64 {
+	return atomic.AddInt64(aa.ptr(), v)
+}
+
+// AlignedAtomicUint64 is an atomic uint64 that is guaranteed to be 64-bit
+// aligned, even on 32-bit systems.
+//
+// Per https://golang.org/pkg/sync/atomic/#pkg-note-BUG:
+//
+// "On ARM, 386, and 32-bit MIPS, it is the caller's responsibility to arrange
+// for 64-bit alignment of 64-bit words accessed atomically. The first word in
+// a variable or in an allocated struct, array, or slice can be relied upon to
+// be 64-bit aligned."
+type AlignedAtomicUint64 struct {
+	value [15]byte
+}
+
+func (aa *AlignedAtomicUint64) ptr() *uint64 {
+	return (*uint64)(unsafe.Pointer((uintptr(unsafe.Pointer(&aa.value)) + 7) &^ 7))
+}
+
+func (aa *AlignedAtomicUint64) Load() uint64 {
+	return atomic.LoadUint64(aa.ptr())
+}
+
+func (aa *AlignedAtomicUint64) Store(v uint64) {
+	atomic.StoreUint64(aa.ptr(), v)
+}
+
+func (aa *AlignedAtomicUint64) Add(v uint64) uint64 {
+	return atomic.AddUint64(aa.ptr(), v)
+}
diff --git a/pkg/tcpip/socketops.go b/pkg/tcpip/socketops.go
index a6c877158..8158e238d 100644
--- a/pkg/tcpip/socketops.go
+++ b/pkg/tcpip/socketops.go
@@ -213,7 +213,7 @@ type SocketOptions struct {
 	getSendBufferLimits GetSendBufferLimits `state:"manual"`
 
 	// sendBufferSize determines the send buffer size for this socket.
-	sendBufferSize int64
+	sendBufferSize AlignedAtomicInt64
 
 	// getReceiveBufferLimits provides the handler to get the min, default and
 	// max size for receive buffer. It is initialized at the creation time and
@@ -612,7 +612,7 @@ func (so *SocketOptions) SetBindToDevice(bindToDevice int32) Error {
 
 // GetSendBufferSize gets value for SO_SNDBUF option.
 func (so *SocketOptions) GetSendBufferSize() int64 {
-	return atomic.LoadInt64(&so.sendBufferSize)
+	return so.sendBufferSize.Load()
 }
 
 // SetSendBufferSize sets value for SO_SNDBUF option. notify indicates if the
@@ -621,7 +621,7 @@ func (so *SocketOptions) SetSendBufferSize(sendBufferSize int64, notify bool) {
 	v := sendBufferSize
 
 	if !notify {
-		atomic.StoreInt64(&so.sendBufferSize, v)
+		so.sendBufferSize.Store(v)
 		return
 	}
 
@@ -647,7 +647,7 @@ func (so *SocketOptions) SetSendBufferSize(sendBufferSize int64, notify bool) {
 
 	// Notify endpoint about change in buffer size.
 	newSz := so.handler.OnSetSendBufferSize(v)
-	atomic.StoreInt64(&so.sendBufferSize, newSz)
+	so.sendBufferSize.Store(newSz)
 }
 
 // GetReceiveBufferSize gets value for SO_RCVBUF option.
diff --git a/pkg/tcpip/tcpip.go b/pkg/tcpip/tcpip.go
index d5f941c5f..1bc13ef68 100644
--- a/pkg/tcpip/tcpip.go
+++ b/pkg/tcpip/tcpip.go
@@ -1220,7 +1220,7 @@ type NetworkProtocolNumber uint32
 
 // A StatCounter keeps track of a statistic.
 type StatCounter struct {
-	count uint64
+	count AlignedAtomicUint64
 }
 
 // Increment adds one to the counter.
@@ -1240,7 +1240,7 @@ func (s *StatCounter) Value(name ...string) uint64 {
 
 // IncrementBy increments the counter by v.
 func (s *StatCounter) IncrementBy(v uint64) {
-	atomic.AddUint64(&s.count, v)
+	s.count.Add(v)
 }
 
 func (s *StatCounter) String() string {

From 1e2ba2666135e7f28cb3c4185add5a257ad53637 Mon Sep 17 00:00:00 2001
From: Kevin Krakauer <krakauer@google.com>
Date: Fri, 19 Mar 2021 13:44:26 -0700
Subject: [PATCH 2/8] Moved to atomicbitops and renamed files

---
 pkg/atomicbitops/BUILD                                       | 2 ++
 .../aligned_32bit_unsafe.go}                                 | 2 +-
 pkg/{tcpip/aligned.go => atomicbitops/aligned_64bit.go}      | 2 +-
 pkg/tcpip/BUILD                                              | 3 +--
 pkg/tcpip/socketops.go                                       | 3 ++-
 pkg/tcpip/stack/BUILD                                        | 1 +
 pkg/tcpip/stack/stack.go                                     | 5 +++--
 pkg/tcpip/tcpip.go                                           | 3 ++-
 8 files changed, 13 insertions(+), 8 deletions(-)
 rename pkg/{tcpip/aligned_unsafe.go => atomicbitops/aligned_32bit_unsafe.go} (99%)
 rename pkg/{tcpip/aligned.go => atomicbitops/aligned_64bit.go} (98%)

diff --git a/pkg/atomicbitops/BUILD b/pkg/atomicbitops/BUILD
index 1a30f6967..11072d4de 100644
--- a/pkg/atomicbitops/BUILD
+++ b/pkg/atomicbitops/BUILD
@@ -5,6 +5,8 @@ package(licenses = ["notice"])
 go_library(
     name = "atomicbitops",
     srcs = [
+        "aligned_32bit_unsafe.go",
+        "aligned_64bit.go",
         "atomicbitops.go",
         "atomicbitops_amd64.s",
         "atomicbitops_arm64.s",
diff --git a/pkg/tcpip/aligned_unsafe.go b/pkg/atomicbitops/aligned_32bit_unsafe.go
similarity index 99%
rename from pkg/tcpip/aligned_unsafe.go
rename to pkg/atomicbitops/aligned_32bit_unsafe.go
index 35e869453..1d71a0641 100644
--- a/pkg/tcpip/aligned_unsafe.go
+++ b/pkg/atomicbitops/aligned_32bit_unsafe.go
@@ -14,7 +14,7 @@
 
 // +build arm 386
 
-package tcpip
+package atomicbitops
 
 import (
 	"sync/atomic"
diff --git a/pkg/tcpip/aligned.go b/pkg/atomicbitops/aligned_64bit.go
similarity index 98%
rename from pkg/tcpip/aligned.go
rename to pkg/atomicbitops/aligned_64bit.go
index ea22c101f..21043c53d 100644
--- a/pkg/tcpip/aligned.go
+++ b/pkg/atomicbitops/aligned_64bit.go
@@ -14,7 +14,7 @@
 
 // +build !arm,!386
 
-package tcpip
+package atomicbitops
 
 import "sync/atomic"
 
diff --git a/pkg/tcpip/BUILD b/pkg/tcpip/BUILD
index 5237eba76..ea46c30da 100644
--- a/pkg/tcpip/BUILD
+++ b/pkg/tcpip/BUILD
@@ -19,8 +19,6 @@ go_template_instance(
 go_library(
     name = "tcpip",
     srcs = [
-        "aligned.go",
-        "aligned_unsafe.go",
         "errors.go",
         "sock_err_list.go",
         "socketops.go",
@@ -31,6 +29,7 @@ go_library(
     ],
     visibility = ["//visibility:public"],
     deps = [
+        "//pkg/atomicbitops",
         "//pkg/sync",
         "//pkg/tcpip/buffer",
         "//pkg/waiter",
diff --git a/pkg/tcpip/socketops.go b/pkg/tcpip/socketops.go
index 8158e238d..b26936b7f 100644
--- a/pkg/tcpip/socketops.go
+++ b/pkg/tcpip/socketops.go
@@ -18,6 +18,7 @@ import (
 	"math"
 	"sync/atomic"
 
+	"gvisor.dev/gvisor/pkg/atomicbitops"
 	"gvisor.dev/gvisor/pkg/sync"
 )
 
@@ -213,7 +214,7 @@ type SocketOptions struct {
 	getSendBufferLimits GetSendBufferLimits `state:"manual"`
 
 	// sendBufferSize determines the send buffer size for this socket.
-	sendBufferSize AlignedAtomicInt64
+	sendBufferSize atomicbitops.AlignedAtomicInt64
 
 	// getReceiveBufferLimits provides the handler to get the min, default and
 	// max size for receive buffer. It is initialized at the creation time and
diff --git a/pkg/tcpip/stack/BUILD b/pkg/tcpip/stack/BUILD
index 2bd6a67f5..63ab31083 100644
--- a/pkg/tcpip/stack/BUILD
+++ b/pkg/tcpip/stack/BUILD
@@ -73,6 +73,7 @@ go_library(
     ],
     visibility = ["//visibility:public"],
     deps = [
+        "//pkg/atomicbitops",
         "//pkg/ilist",
         "//pkg/log",
         "//pkg/rand",
diff --git a/pkg/tcpip/stack/stack.go b/pkg/tcpip/stack/stack.go
index 436392f23..3d9e1e286 100644
--- a/pkg/tcpip/stack/stack.go
+++ b/pkg/tcpip/stack/stack.go
@@ -29,6 +29,7 @@ import (
 	"time"
 
 	"golang.org/x/time/rate"
+	"gvisor.dev/gvisor/pkg/atomicbitops"
 	"gvisor.dev/gvisor/pkg/rand"
 	"gvisor.dev/gvisor/pkg/sync"
 	"gvisor.dev/gvisor/pkg/tcpip"
@@ -65,10 +66,10 @@ type ResumableEndpoint interface {
 }
 
 // uniqueIDGenerator is a default unique ID generator.
-type uniqueIDGenerator uint64
+type uniqueIDGenerator atomicbitops.AlignedAtomicUint64
 
 func (u *uniqueIDGenerator) UniqueID() uint64 {
-	return atomic.AddUint64((*uint64)(u), 1)
+	return ((*atomicbitops.AlignedAtomicUint64)(u)).Add(1)
 }
 
 // Stack is a networking stack, with all supported protocols, NICs, and route
diff --git a/pkg/tcpip/tcpip.go b/pkg/tcpip/tcpip.go
index 1bc13ef68..b39af42c4 100644
--- a/pkg/tcpip/tcpip.go
+++ b/pkg/tcpip/tcpip.go
@@ -40,6 +40,7 @@ import (
 	"sync/atomic"
 	"time"
 
+	"gvisor.dev/gvisor/pkg/atomicbitops"
 	"gvisor.dev/gvisor/pkg/sync"
 	"gvisor.dev/gvisor/pkg/waiter"
 )
@@ -1220,7 +1221,7 @@ type NetworkProtocolNumber uint32
 
 // A StatCounter keeps track of a statistic.
 type StatCounter struct {
-	count AlignedAtomicUint64
+	count atomicbitops.AlignedAtomicUint64
 }
 
 // Increment adds one to the counter.

From 413f1d654f2b0fb8c43fe9e22d8083789abdf856 Mon Sep 17 00:00:00 2001
From: Kevin Krakauer <krakauer@google.com>
Date: Fri, 19 Mar 2021 14:19:16 -0700
Subject: [PATCH 3/8] Added comments

---
 pkg/atomicbitops/aligned_32bit_unsafe.go | 6 ++++++
 pkg/atomicbitops/aligned_64bit.go        | 6 ++++++
 2 files changed, 12 insertions(+)

diff --git a/pkg/atomicbitops/aligned_32bit_unsafe.go b/pkg/atomicbitops/aligned_32bit_unsafe.go
index 1d71a0641..a5c762f67 100644
--- a/pkg/atomicbitops/aligned_32bit_unsafe.go
+++ b/pkg/atomicbitops/aligned_32bit_unsafe.go
@@ -38,14 +38,17 @@ func (aa *AlignedAtomicInt64) ptr() *int64 {
 	return (*int64)(unsafe.Pointer((uintptr(unsafe.Pointer(&aa.value)) + 7) &^ 7))
 }
 
+// Load is analagous to atomic.LoadInt64.
 func (aa *AlignedAtomicInt64) Load() int64 {
 	return atomic.LoadInt64(aa.ptr())
 }
 
+// Store is analagous to atomic.StoreInt64.
 func (aa *AlignedAtomicInt64) Store(v int64) {
 	atomic.StoreInt64(aa.ptr(), v)
 }
 
+// Add is analagous to atomic.AddInt64.
 func (aa *AlignedAtomicInt64) Add(v int64) int64 {
 	return atomic.AddInt64(aa.ptr(), v)
 }
@@ -67,14 +70,17 @@ func (aa *AlignedAtomicUint64) ptr() *uint64 {
 	return (*uint64)(unsafe.Pointer((uintptr(unsafe.Pointer(&aa.value)) + 7) &^ 7))
 }
 
+// Load is analagous to atomic.LoadUint64.
 func (aa *AlignedAtomicUint64) Load() uint64 {
 	return atomic.LoadUint64(aa.ptr())
 }
 
+// Store is analagous to atomic.StoreUint64.
 func (aa *AlignedAtomicUint64) Store(v uint64) {
 	atomic.StoreUint64(aa.ptr(), v)
 }
 
+// Add is analagous to atomic.AddUint64.
 func (aa *AlignedAtomicUint64) Add(v uint64) uint64 {
 	return atomic.AddUint64(aa.ptr(), v)
 }
diff --git a/pkg/atomicbitops/aligned_64bit.go b/pkg/atomicbitops/aligned_64bit.go
index 21043c53d..5898653d8 100644
--- a/pkg/atomicbitops/aligned_64bit.go
+++ b/pkg/atomicbitops/aligned_64bit.go
@@ -27,14 +27,17 @@ type AlignedAtomicInt64 struct {
 	value int64
 }
 
+// Load is analagous to atomic.LoadInt64.
 func (aa *AlignedAtomicInt64) Load() int64 {
 	return atomic.LoadInt64(&aa.value)
 }
 
+// Store is analagous to atomic.StoreInt64.
 func (aa *AlignedAtomicInt64) Store(v int64) {
 	atomic.StoreInt64(&aa.value, v)
 }
 
+// Add is analagous to atomic.AddInt64.
 func (aa *AlignedAtomicInt64) Add(v int64) int64 {
 	return atomic.AddInt64(&aa.value, v)
 }
@@ -48,14 +51,17 @@ type AlignedAtomicUint64 struct {
 	value uint64
 }
 
+// Load is analagous to atomic.LoadUint64.
 func (aa *AlignedAtomicUint64) Load() uint64 {
 	return atomic.LoadUint64(&aa.value)
 }
 
+// Store is analagous to atomic.StoreUint64.
 func (aa *AlignedAtomicUint64) Store(v uint64) {
 	atomic.StoreUint64(&aa.value, v)
 }
 
+// Add is analagous to atomic.AddUint64.
 func (aa *AlignedAtomicUint64) Add(v uint64) uint64 {
 	return atomic.AddUint64(&aa.value, v)
 }

From a6c623ed9f971d6fbebddaf9ad03d357994647cc Mon Sep 17 00:00:00 2001
From: Kevin Krakauer <krakauer@google.com>
Date: Tue, 30 Mar 2021 15:03:08 -0700
Subject: [PATCH 4/8] Added more comments

---
 pkg/atomicbitops/aligned_32bit_unsafe.go | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/pkg/atomicbitops/aligned_32bit_unsafe.go b/pkg/atomicbitops/aligned_32bit_unsafe.go
index a5c762f67..200fc0092 100644
--- a/pkg/atomicbitops/aligned_32bit_unsafe.go
+++ b/pkg/atomicbitops/aligned_32bit_unsafe.go
@@ -35,6 +35,9 @@ type AlignedAtomicInt64 struct {
 }
 
 func (aa *AlignedAtomicInt64) ptr() *int64 {
+	// In the 15-byte aa.value, there are guaranteed to be 8 contiguous
+	// bytes with 64-bit alignment. We find an address in this range by
+	// adding 7, then clear the 3 least significant bits to get its start.
 	return (*int64)(unsafe.Pointer((uintptr(unsafe.Pointer(&aa.value)) + 7) &^ 7))
 }
 
@@ -67,6 +70,9 @@ type AlignedAtomicUint64 struct {
 }
 
 func (aa *AlignedAtomicUint64) ptr() *uint64 {
+	// In the 15-byte aa.value, there are guaranteed to be 8 contiguous
+	// bytes with 64-bit alignment. We find an address in this range by
+	// adding 7, then clear the 3 least significant bits to get its start.
 	return (*uint64)(unsafe.Pointer((uintptr(unsafe.Pointer(&aa.value)) + 7) &^ 7))
 }
 

From eded0d28de7f62423e496d89fd2699bb02e2744f Mon Sep 17 00:00:00 2001
From: Kevin Krakauer <krakauer@google.com>
Date: Mon, 5 Apr 2021 11:54:50 -0700
Subject: [PATCH 5/8] mark types as saveable

---
 pkg/atomicbitops/aligned_32bit_unsafe.go | 4 ++++
 pkg/atomicbitops/aligned_64bit.go        | 4 ++++
 2 files changed, 8 insertions(+)

diff --git a/pkg/atomicbitops/aligned_32bit_unsafe.go b/pkg/atomicbitops/aligned_32bit_unsafe.go
index 200fc0092..3ebbee7b1 100644
--- a/pkg/atomicbitops/aligned_32bit_unsafe.go
+++ b/pkg/atomicbitops/aligned_32bit_unsafe.go
@@ -30,6 +30,8 @@ import (
 // for 64-bit alignment of 64-bit words accessed atomically. The first word in
 // a variable or in an allocated struct, array, or slice can be relied upon to
 // be 64-bit aligned."
+//
+// +stateify savable
 type AlignedAtomicInt64 struct {
 	value [15]byte
 }
@@ -65,6 +67,8 @@ func (aa *AlignedAtomicInt64) Add(v int64) int64 {
 // for 64-bit alignment of 64-bit words accessed atomically. The first word in
 // a variable or in an allocated struct, array, or slice can be relied upon to
 // be 64-bit aligned."
+//
+// +stateify savable
 type AlignedAtomicUint64 struct {
 	value [15]byte
 }
diff --git a/pkg/atomicbitops/aligned_64bit.go b/pkg/atomicbitops/aligned_64bit.go
index 5898653d8..0f3da590f 100644
--- a/pkg/atomicbitops/aligned_64bit.go
+++ b/pkg/atomicbitops/aligned_64bit.go
@@ -23,6 +23,8 @@ import "sync/atomic"
 // int64.
 //
 // See aligned_unsafe.go in this directory for justification.
+//
+// +stateify savable
 type AlignedAtomicInt64 struct {
 	value int64
 }
@@ -47,6 +49,8 @@ func (aa *AlignedAtomicInt64) Add(v int64) int64 {
 // uint64.
 //
 // See aligned_unsafe.go in this directory for justification.
+//
+// +stateify savable
 type AlignedAtomicUint64 struct {
 	value uint64
 }

From b8681e6093e5f818c385f83a91be545cc35e07a9 Mon Sep 17 00:00:00 2001
From: Kevin Krakauer <krakauer@google.com>
Date: Thu, 6 May 2021 13:56:00 -0700
Subject: [PATCH 6/8] fix rebase error

---
 pkg/tcpip/tcpip.go | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/pkg/tcpip/tcpip.go b/pkg/tcpip/tcpip.go
index b39af42c4..7e7415df4 100644
--- a/pkg/tcpip/tcpip.go
+++ b/pkg/tcpip/tcpip.go
@@ -37,7 +37,6 @@ import (
 	"reflect"
 	"strconv"
 	"strings"
-	"sync/atomic"
 	"time"
 
 	"gvisor.dev/gvisor/pkg/atomicbitops"
@@ -1236,7 +1235,7 @@ func (s *StatCounter) Decrement() {
 
 // Value returns the current value of the counter.
 func (s *StatCounter) Value(name ...string) uint64 {
-	return atomic.LoadUint64(&s.count)
+	return s.count.Load()
 }
 
 // IncrementBy increments the counter by v.

From 66de003e19642b5d6eb6d3f7660ad638271f3477 Mon Sep 17 00:00:00 2001
From: Kevin Krakauer <krakauer@google.com>
Date: Thu, 6 May 2021 15:01:09 -0700
Subject: [PATCH 7/8] fix build constraints

---
 pkg/atomicbitops/aligned_64bit.go | 2 +-
 tools/bazeldefs/tags.bzl          | 4 ++++
 2 files changed, 5 insertions(+), 1 deletion(-)

diff --git a/pkg/atomicbitops/aligned_64bit.go b/pkg/atomicbitops/aligned_64bit.go
index 0f3da590f..869ba40cd 100644
--- a/pkg/atomicbitops/aligned_64bit.go
+++ b/pkg/atomicbitops/aligned_64bit.go
@@ -12,7 +12,7 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-// +build !arm,!386
+// +build amd64 arm64
 
 package atomicbitops
 
diff --git a/tools/bazeldefs/tags.bzl b/tools/bazeldefs/tags.bzl
index f5d7a7b21..6564c3b25 100644
--- a/tools/bazeldefs/tags.bzl
+++ b/tools/bazeldefs/tags.bzl
@@ -33,6 +33,10 @@ archs = [
     "_s390x",
     "_sparc64",
     "_x86",
+
+    # Pseudo-architectures to group by word side.
+    "_32bit",
+    "_64bit",
 ]
 
 oses = [

From 314a5f8d7e7402e66ba5d22f79fa13143a7b69d0 Mon Sep 17 00:00:00 2001
From: Kevin Krakauer <krakauer@google.com>
Date: Fri, 7 May 2021 13:51:09 -0700
Subject: [PATCH 8/8] explicitly 0-index backing array

---
 pkg/atomicbitops/aligned_32bit_unsafe.go | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/pkg/atomicbitops/aligned_32bit_unsafe.go b/pkg/atomicbitops/aligned_32bit_unsafe.go
index 3ebbee7b1..776da53b0 100644
--- a/pkg/atomicbitops/aligned_32bit_unsafe.go
+++ b/pkg/atomicbitops/aligned_32bit_unsafe.go
@@ -40,7 +40,7 @@ func (aa *AlignedAtomicInt64) ptr() *int64 {
 	// In the 15-byte aa.value, there are guaranteed to be 8 contiguous
 	// bytes with 64-bit alignment. We find an address in this range by
 	// adding 7, then clear the 3 least significant bits to get its start.
-	return (*int64)(unsafe.Pointer((uintptr(unsafe.Pointer(&aa.value)) + 7) &^ 7))
+	return (*int64)(unsafe.Pointer((uintptr(unsafe.Pointer(&aa.value[0])) + 7) &^ 7))
 }
 
 // Load is analagous to atomic.LoadInt64.
@@ -77,7 +77,7 @@ func (aa *AlignedAtomicUint64) ptr() *uint64 {
 	// In the 15-byte aa.value, there are guaranteed to be 8 contiguous
 	// bytes with 64-bit alignment. We find an address in this range by
 	// adding 7, then clear the 3 least significant bits to get its start.
-	return (*uint64)(unsafe.Pointer((uintptr(unsafe.Pointer(&aa.value)) + 7) &^ 7))
+	return (*uint64)(unsafe.Pointer((uintptr(unsafe.Pointer(&aa.value[0])) + 7) &^ 7))
 }
 
 // Load is analagous to atomic.LoadUint64.