Consolidate most synchronization primitive linknames in the sync package.

PiperOrigin-RevId: 345359823

21 files changed, 161 insertions, 336 deletions

diff --git a/pkg/sleep/BUILD b/pkg/sleep/BUILD
index ae0fe1522..48bcdd62b 100644
--- a/pkg/sleep/BUILD
+++ b/pkg/sleep/BUILD
@@ -5,10 +5,6 @@ package(licenses = ["notice"])
 go_library(
     name = "sleep",
     srcs = [
-        "commit_amd64.s",
-        "commit_arm64.s",
-        "commit_asm.go",
-        "commit_noasm.go",
         "sleep_unsafe.go",
     ],
     visibility = ["//:sandbox"],
diff --git a/pkg/sleep/commit_amd64.s b/pkg/sleep/commit_amd64.s
deleted file mode 100644
index bc4ac2c3c..000000000
--- a/pkg/sleep/commit_amd64.s
+++ /dev/null
@@ -1,35 +0,0 @@
-// 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.
-
-#include "textflag.h"
-
-#define preparingG 1
-
-// See commit_noasm.go for a description of commitSleep.
-//
-// func commitSleep(g uintptr, waitingG *uintptr) bool
-TEXT ·commitSleep(SB),NOSPLIT,$0-24
-	MOVQ waitingG+8(FP), CX
-	MOVQ g+0(FP), DX
-
-	// Store the G in waitingG if it's still preparingG. If it's anything
-	// else it means a waker has aborted the sleep.
-	MOVQ $preparingG, AX
-	LOCK
-	CMPXCHGQ DX, 0(CX)
-
-	SETEQ AX
-	MOVB AX, ret+16(FP)
-
-	RET
diff --git a/pkg/sleep/commit_arm64.s b/pkg/sleep/commit_arm64.s
deleted file mode 100644
index d0ef15b20..000000000
--- a/pkg/sleep/commit_arm64.s
+++ /dev/null
@@ -1,38 +0,0 @@
-// Copyright 2019 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.
-
-#include "textflag.h"
-
-#define preparingG 1
-
-// See commit_noasm.go for a description of commitSleep.
-//
-// func commitSleep(g uintptr, waitingG *uintptr) bool
-TEXT ·commitSleep(SB),NOSPLIT,$0-24
-	MOVD waitingG+8(FP), R0
-	MOVD $preparingG, R1
-	MOVD G+0(FP), R2
-
-	// Store the G in waitingG if it's still preparingG. If it's anything
-	// else it means a waker has aborted the sleep.
-again:
-        LDAXR   (R0), R3
-        CMP     R1, R3
-        BNE     ok
-        STLXR   R2, (R0), R3
-        CBNZ    R3, again
-ok:
-        CSET    EQ, R0
-        MOVB    R0, ret+16(FP)
-        RET
diff --git a/pkg/sleep/commit_asm.go b/pkg/sleep/commit_asm.go
deleted file mode 100644
index 75728a97d..000000000
--- a/pkg/sleep/commit_asm.go
+++ /dev/null
@@ -1,20 +0,0 @@
-// 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.
-
-// +build amd64 arm64
-
-package sleep
-
-// See commit_noasm.go for a description of commitSleep.
-func commitSleep(g uintptr, waitingG *uintptr) bool
diff --git a/pkg/sleep/commit_noasm.go b/pkg/sleep/commit_noasm.go
deleted file mode 100644
index f59061f37..000000000
--- a/pkg/sleep/commit_noasm.go
+++ /dev/null
@@ -1,33 +0,0 @@
-// 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.
-
-// +build !race
-// +build !amd64,!arm64
-
-package sleep
-
-import "sync/atomic"
-
-// commitSleep signals to wakers that the given g is now sleeping. Wakers can
-// then fetch it and wake it.
-//
-// The commit may fail if wakers have been asserted after our last check, in
-// which case they will have set s.waitingG to zero.
-//
-// It is written in assembly because it is called from g0, so it doesn't have
-// a race context.
-func commitSleep(g uintptr, waitingG *uintptr) bool {
-	// Try to store the G so that wakers know who to wake.
-	return atomic.CompareAndSwapUintptr(waitingG, preparingG, g)
-}
diff --git a/pkg/sleep/empty.s b/pkg/sleep/empty.s
deleted file mode 100644
index fb37360ac..000000000
--- a/pkg/sleep/empty.s
+++ /dev/null
@@ -1,15 +0,0 @@
-// 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.
-
-// Empty assembly file so empty func definitions work.
diff --git a/pkg/sleep/sleep_unsafe.go b/pkg/sleep/sleep_unsafe.go
index 19bce2afb..c44206b1e 100644
--- a/pkg/sleep/sleep_unsafe.go
+++ b/pkg/sleep/sleep_unsafe.go
@@ -12,11 +12,6 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-// +build go1.11
-// +build !go1.17
-
-// Check go:linkname function signatures when updating Go version.
-
 // Package sleep allows goroutines to efficiently sleep on multiple sources of
 // notifications (wakers). It offers O(1) complexity, which is different from
 // multi-channel selects which have O(n) complexity (where n is the number of
@@ -91,12 +86,6 @@ var (
 	assertedSleeper Sleeper
 )
 
-//go:linkname gopark runtime.gopark
-func gopark(unlockf func(uintptr, *uintptr) bool, wg *uintptr, reason uint8, traceEv byte, traceskip int)
-
-//go:linkname goready runtime.goready
-func goready(g uintptr, traceskip int)
-
 // Sleeper allows a goroutine to sleep and receive wake up notifications from
 // Wakers in an efficient way.
 //
@@ -189,7 +178,7 @@ func (s *Sleeper) nextWaker(block bool) *Waker {
 			// See:runtime2.go in the go runtime package for
 			// the values to pass as the waitReason here.
 			const waitReasonSelect = 9
-			gopark(commitSleep, &s.waitingG, waitReasonSelect, traceEvGoBlockSelect, 0)
+			sync.Gopark(commitSleep, unsafe.Pointer(&s.waitingG), sync.WaitReasonSelect, sync.TraceEvGoBlockSelect, 0)
 		}
 
 		// Pull the shared list out and reverse it in the local
@@ -212,6 +201,18 @@ func (s *Sleeper) nextWaker(block bool) *Waker {
 	return w
 }
 
+// commitSleep signals to wakers that the given g is now sleeping. Wakers can
+// then fetch it and wake it.
+//
+// The commit may fail if wakers have been asserted after our last check, in
+// which case they will have set s.waitingG to zero.
+//
+//go:norace
+//go:nosplit
+func commitSleep(g uintptr, waitingG unsafe.Pointer) bool {
+	return sync.RaceUncheckedAtomicCompareAndSwapUintptr((*uintptr)(waitingG), preparingG, g)
+}
+
 // Fetch fetches the next wake-up notification. If a notification is immediately
 // available, it is returned right away. Otherwise, the behavior depends on the
 // value of 'block': if true, the current goroutine blocks until a notification
@@ -311,7 +312,7 @@ func (s *Sleeper) enqueueAssertedWaker(w *Waker) {
 	case 0, preparingG:
 	default:
 		// We managed to get a G. Wake it up.
-		goready(g, 0)
+		sync.Goready(g, 0)
 	}
 }
 
diff --git a/pkg/sync/BUILD b/pkg/sync/BUILD
index 5bd4d09d1..be5bc99fc 100644
--- a/pkg/sync/BUILD
+++ b/pkg/sync/BUILD
@@ -33,15 +33,17 @@ go_library(
         "aliases.go",
         "checklocks_off_unsafe.go",
         "checklocks_on_unsafe.go",
-        "memmove_unsafe.go",
+        "goyield_go113_unsafe.go",
+        "goyield_unsafe.go",
         "mutex_unsafe.go",
         "nocopy.go",
         "norace_unsafe.go",
+        "race_amd64.s",
+        "race_arm64.s",
         "race_unsafe.go",
+        "runtime_unsafe.go",
         "rwmutex_unsafe.go",
         "seqcount.go",
-        "spin_legacy_unsafe.go",
-        "spin_unsafe.go",
         "sync.go",
     ],
     marshal = False,
diff --git a/pkg/sync/spin_legacy_unsafe.go b/pkg/sync/goyield_go113_unsafe.go
index 61fc7320e..8aee0d455 100644
--- a/pkg/sync/spin_legacy_unsafe.go
+++ b/pkg/sync/goyield_go113_unsafe.go
@@ -10,15 +10,8 @@ package sync
 
 import (
 	"runtime"
-	_ "unsafe" // for go:linkname
 )
 
-//go:linkname canSpin sync.runtime_canSpin
-func canSpin(i int) bool
-
-//go:linkname doSpin sync.runtime_doSpin
-func doSpin()
-
 func goyield() {
 	// goyield is not available until Go 1.14.
 	runtime.Gosched()
diff --git a/pkg/sync/spin_unsafe.go b/pkg/sync/goyield_unsafe.go
index 18e8fc743..672ee274d 100644
--- a/pkg/sync/spin_unsafe.go
+++ b/pkg/sync/goyield_unsafe.go
@@ -14,11 +14,5 @@ import (
 	_ "unsafe" // for go:linkname
 )
 
-//go:linkname canSpin sync.runtime_canSpin
-func canSpin(i int) bool
-
-//go:linkname doSpin sync.runtime_doSpin
-func doSpin()
-
 //go:linkname goyield runtime.goyield
 func goyield()
diff --git a/pkg/sync/memmove_unsafe.go b/pkg/sync/memmove_unsafe.go
deleted file mode 100644
index f5e630009..000000000
--- a/pkg/sync/memmove_unsafe.go
+++ /dev/null
@@ -1,28 +0,0 @@
-// Copyright 2019 The gVisor Authors.
-//
-// Use of this source code is governed by a BSD-style
-// license that can be found in the LICENSE file.
-
-// +build go1.12
-// +build !go1.17
-
-// Check go:linkname function signatures when updating Go version.
-
-package sync
-
-import (
-	"unsafe"
-)
-
-//go:linkname memmove runtime.memmove
-//go:noescape
-func memmove(to, from unsafe.Pointer, n uintptr)
-
-// Memmove is exported for SeqAtomicLoad/SeqAtomicTryLoad<T>, which can't
-// define it because go_generics can't update the go:linkname annotation.
-// Furthermore, go:linkname silently doesn't work if the local name is exported
-// (this is of course undocumented), which is why this indirection is
-// necessary.
-func Memmove(to, from unsafe.Pointer, n uintptr) {
-	memmove(to, from, n)
-}
diff --git a/pkg/sync/norace_unsafe.go b/pkg/sync/norace_unsafe.go
index 006055dd6..70b5f3a5e 100644
--- a/pkg/sync/norace_unsafe.go
+++ b/pkg/sync/norace_unsafe.go
@@ -8,6 +8,7 @@
 package sync
 
 import (
+	"sync/atomic"
 	"unsafe"
 )
 
@@ -33,3 +34,13 @@ func RaceRelease(addr unsafe.Pointer) {
 // RaceReleaseMerge has the same semantics as runtime.RaceReleaseMerge.
 func RaceReleaseMerge(addr unsafe.Pointer) {
 }
+
+// RaceUncheckedAtomicCompareAndSwapUintptr is equivalent to
+// sync/atomic.CompareAndSwapUintptr, but is not checked by the race detector.
+// This is necessary when implementing gopark callbacks, since no race context
+// is available during their execution.
+func RaceUncheckedAtomicCompareAndSwapUintptr(ptr *uintptr, old, new uintptr) bool {
+	// Use atomic.CompareAndSwapUintptr outside of race builds for
+	// inlinability.
+	return atomic.CompareAndSwapUintptr(ptr, old, new)
+}
diff --git a/pkg/syncevent/waiter_amd64.s b/pkg/sync/race_amd64.s
index 5e216b045..57bc0ec79 100644
--- a/pkg/syncevent/waiter_amd64.s
+++ b/pkg/sync/race_amd64.s
@@ -12,21 +12,22 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
+// +build race
+// +build amd64
+
 #include "textflag.h"
 
-// See waiter_noasm_unsafe.go for a description of waiterUnlock.
-//
-// func waiterUnlock(ptr unsafe.Pointer, wg *unsafe.Pointer) bool
-TEXT ·waiterUnlock(SB),NOSPLIT,$0-24
+// func RaceUncheckedAtomicCompareAndSwapUintptr(ptr *uintptr, old, new uintptr) bool
+TEXT ·RaceUncheckedAtomicCompareAndSwapUintptr(SB),NOSPLIT,$0-25
 	MOVQ ptr+0(FP), DI
-	MOVQ wg+8(FP), SI
+	MOVQ old+8(FP), AX
+	MOVQ new+16(FP), SI
 
-	MOVQ $·preparingG(SB), AX
 	LOCK
-	CMPXCHGQ DI, 0(SI)
+	CMPXCHGQ SI, 0(DI)
 
 	SETEQ AX
-	MOVB AX, ret+16(FP)
+	MOVB AX, ret+24(FP)
 
 	RET
 
diff --git a/pkg/syncevent/waiter_arm64.s b/pkg/sync/race_arm64.s
index f4c06f194..88f091fda 100644
--- a/pkg/syncevent/waiter_arm64.s
+++ b/pkg/sync/race_arm64.s
@@ -12,15 +12,16 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
+// +build race
+// +build arm64
+
 #include "textflag.h"
 
-// See waiter_noasm_unsafe.go for a description of waiterUnlock.
-//
-// func waiterUnlock(ptr unsafe.Pointer, wg *unsafe.Pointer) bool
-TEXT ·waiterUnlock(SB),NOSPLIT,$0-24
-	MOVD wg+8(FP), R0
-	MOVD $·preparingG(SB), R1
-	MOVD ptr+0(FP), R2
+// func RaceUncheckedAtomicCompareAndSwapUintptr(ptr *uintptr, old, new uintptr) bool
+TEXT ·RaceUncheckedAtomicCompareAndSwapUintptr(SB),NOSPLIT,$0-25
+	MOVD ptr+0(FP), R0
+	MOVD old+8(FP), R1
+	MOVD new+16(FP), R1
 again:
 	LDAXR (R0), R3
 	CMP R1, R3
@@ -29,6 +30,6 @@ again:
 	CBNZ R3, again
 ok:
 	CSET EQ, R0
-	MOVB R0, ret+16(FP)
+	MOVB R0, ret+24(FP)
 	RET
 
diff --git a/pkg/sync/race_unsafe.go b/pkg/sync/race_unsafe.go
index 31d8fa9a6..59985c270 100644
--- a/pkg/sync/race_unsafe.go
+++ b/pkg/sync/race_unsafe.go
@@ -39,3 +39,9 @@ func RaceRelease(addr unsafe.Pointer) {
 func RaceReleaseMerge(addr unsafe.Pointer) {
 	runtime.RaceReleaseMerge(addr)
 }
+
+// RaceUncheckedAtomicCompareAndSwapUintptr is equivalent to
+// sync/atomic.CompareAndSwapUintptr, but is not checked by the race detector.
+// This is necessary when implementing gopark callbacks, since no race context
+// is available during their execution.
+func RaceUncheckedAtomicCompareAndSwapUintptr(ptr *uintptr, old, new uintptr) bool
diff --git a/pkg/sync/runtime_unsafe.go b/pkg/sync/runtime_unsafe.go
new file mode 100644
index 000000000..7ad6a4434
--- /dev/null
+++ b/pkg/sync/runtime_unsafe.go
@@ -0,0 +1,76 @@
+// Copyright 2020 The gVisor Authors.
+//
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// +build go1.13
+// +build !go1.17
+
+// Check function signatures and constants when updating Go version.
+
+package sync
+
+import (
+	"unsafe"
+)
+
+// Note that go:linkname silently doesn't work if the local name is exported,
+// necessitating an indirection for exported functions.
+
+// Memmove is runtime.memmove, exported for SeqAtomicLoad/SeqAtomicTryLoad<T>.
+//
+//go:nosplit
+func Memmove(to, from unsafe.Pointer, n uintptr) {
+	memmove(to, from, n)
+}
+
+//go:linkname memmove runtime.memmove
+//go:noescape
+func memmove(to, from unsafe.Pointer, n uintptr)
+
+// Gopark is runtime.gopark. Gopark calls unlockf(pointer to runtime.g, lock);
+// if unlockf returns true, Gopark blocks until Goready(pointer to runtime.g)
+// is called. unlockf and its callees must be nosplit and norace, since stack
+// splitting and race context are not available where it is called.
+//
+//go:nosplit
+func Gopark(unlockf func(uintptr, unsafe.Pointer) bool, lock unsafe.Pointer, reason uint8, traceEv byte, traceskip int) {
+	gopark(unlockf, lock, reason, traceEv, traceskip)
+}
+
+//go:linkname gopark runtime.gopark
+func gopark(unlockf func(uintptr, unsafe.Pointer) bool, lock unsafe.Pointer, reason uint8, traceEv byte, traceskip int)
+
+// Goready is runtime.goready.
+//
+//go:nosplit
+func Goready(gp uintptr, traceskip int) {
+	goready(gp, traceskip)
+}
+
+//go:linkname goready runtime.goready
+func goready(gp uintptr, traceskip int)
+
+// Values for the reason argument to gopark, from Go's src/runtime/runtime2.go.
+const (
+	WaitReasonSelect uint8 = 9
+)
+
+// Values for the traceEv argument to gopark, from Go's src/runtime/trace.go.
+const (
+	TraceEvGoBlockSelect byte = 24
+)
+
+// These functions are only used within the sync package.
+
+//go:linkname semacquire sync.runtime_Semacquire
+func semacquire(s *uint32)
+
+//go:linkname semrelease sync.runtime_Semrelease
+func semrelease(s *uint32, handoff bool, skipframes int)
+
+//go:linkname canSpin sync.runtime_canSpin
+func canSpin(i int) bool
+
+//go:linkname doSpin sync.runtime_doSpin
+func doSpin()
diff --git a/pkg/sync/rwmutex_unsafe.go b/pkg/sync/rwmutex_unsafe.go
index fa023f5bb..dacd7772c 100644
--- a/pkg/sync/rwmutex_unsafe.go
+++ b/pkg/sync/rwmutex_unsafe.go
@@ -3,11 +3,6 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-// +build go1.13
-// +build !go1.17
-
-// Check go:linkname function signatures when updating Go version.
-
 // This is mostly copied from the standard library's sync/rwmutex.go.
 //
 // Happens-before relationships indicated to the race detector:
@@ -23,16 +18,10 @@ import (
 	"unsafe"
 )
 
-//go:linkname runtimeSemacquire sync.runtime_Semacquire
-func runtimeSemacquire(s *uint32)
-
-//go:linkname runtimeSemrelease sync.runtime_Semrelease
-func runtimeSemrelease(s *uint32, handoff bool, skipframes int)
-
 // RWMutex is identical to sync.RWMutex, but adds the DowngradeLock,
 // TryLock and TryRLock methods.
 type RWMutex struct {
-	// w is held if there are pending writers
+	// w is held by writers.
 	//
 	// We use CrossGoroutineMutex rather than Mutex because the lock
 	// annotation instrumentation in Mutex will trigger false positives in
@@ -78,7 +67,7 @@ func (rw *RWMutex) RLock() {
 	}
 	if atomic.AddInt32(&rw.readerCount, 1) < 0 {
 		// A writer is pending, wait for it.
-		runtimeSemacquire(&rw.readerSem)
+		semacquire(&rw.readerSem)
 	}
 	if RaceEnabled {
 		RaceEnable()
@@ -99,7 +88,7 @@ func (rw *RWMutex) RUnlock() {
 		// A writer is pending.
 		if atomic.AddInt32(&rw.readerWait, -1) == 0 {
 			// The last reader unblocks the writer.
-			runtimeSemrelease(&rw.writerSem, false, 0)
+			semrelease(&rw.writerSem, false, 0)
 		}
 	}
 	if RaceEnabled {
@@ -146,7 +135,7 @@ func (rw *RWMutex) Lock() {
 	r := atomic.AddInt32(&rw.readerCount, -rwmutexMaxReaders) + rwmutexMaxReaders
 	// Wait for active readers.
 	if r != 0 && atomic.AddInt32(&rw.readerWait, r) != 0 {
-		runtimeSemacquire(&rw.writerSem)
+		semacquire(&rw.writerSem)
 	}
 	if RaceEnabled {
 		RaceEnable()
@@ -168,7 +157,7 @@ func (rw *RWMutex) Unlock() {
 	}
 	// Unblock blocked readers, if any.
 	for i := 0; i < int(r); i++ {
-		runtimeSemrelease(&rw.readerSem, false, 0)
+		semrelease(&rw.readerSem, false, 0)
 	}
 	// Allow other writers to proceed.
 	rw.w.Unlock()
@@ -191,7 +180,7 @@ func (rw *RWMutex) DowngradeLock() {
 	// Unblock blocked readers, if any. Note that this loop starts as 1 since r
 	// includes this goroutine.
 	for i := 1; i < int(r); i++ {
-		runtimeSemrelease(&rw.readerSem, false, 0)
+		semrelease(&rw.readerSem, false, 0)
 	}
 	// Allow other writers to proceed to rw.w.Lock(). Note that they will still
 	// block on rw.writerSem since at least this reader exists, such that
diff --git a/pkg/syncevent/BUILD b/pkg/syncevent/BUILD
index 0500a22cf..42c553308 100644
--- a/pkg/syncevent/BUILD
+++ b/pkg/syncevent/BUILD
@@ -9,10 +9,6 @@ go_library(
         "receiver.go",
         "source.go",
         "syncevent.go",
-        "waiter_amd64.s",
-        "waiter_arm64.s",
-        "waiter_asm_unsafe.go",
-        "waiter_noasm_unsafe.go",
         "waiter_unsafe.go",
     ],
     visibility = ["//:sandbox"],
diff --git a/pkg/syncevent/waiter_asm_unsafe.go b/pkg/syncevent/waiter_asm_unsafe.go
deleted file mode 100644
index 19d6b0b15..000000000
--- a/pkg/syncevent/waiter_asm_unsafe.go
+++ /dev/null
@@ -1,24 +0,0 @@
-// Copyright 2020 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 amd64 arm64
-
-package syncevent
-
-import (
-	"unsafe"
-)
-
-// See waiter_noasm_unsafe.go for a description of waiterUnlock.
-func waiterUnlock(ptr unsafe.Pointer, wg *unsafe.Pointer) bool
diff --git a/pkg/syncevent/waiter_noasm_unsafe.go b/pkg/syncevent/waiter_noasm_unsafe.go
deleted file mode 100644
index 0f74a689c..000000000
--- a/pkg/syncevent/waiter_noasm_unsafe.go
+++ /dev/null
@@ -1,39 +0,0 @@
-// Copyright 2020 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.
-
-// waiterUnlock is called from g0, so when the race detector is enabled,
-// waiterUnlock must be implemented in assembly since no race context is
-// available.
-//
-// +build !race
-// +build !amd64,!arm64
-
-package syncevent
-
-import (
-	"sync/atomic"
-	"unsafe"
-)
-
-// waiterUnlock is the "unlock function" passed to runtime.gopark by
-// Waiter.Wait*. wg is &Waiter.g, and g is a pointer to the calling runtime.g.
-// waiterUnlock returns true if Waiter.Wait should sleep and false if sleeping
-// should be aborted.
-//
-//go:nosplit
-func waiterUnlock(ptr unsafe.Pointer, wg *unsafe.Pointer) bool {
-	// The only way this CAS can fail is if a call to Waiter.NotifyPending()
-	// has replaced *wg with nil, in which case we should not sleep.
-	return atomic.CompareAndSwapPointer(wg, (unsafe.Pointer)(&preparingG), ptr)
-}
diff --git a/pkg/syncevent/waiter_unsafe.go b/pkg/syncevent/waiter_unsafe.go
index 518f18479..b6ed2852d 100644
--- a/pkg/syncevent/waiter_unsafe.go
+++ b/pkg/syncevent/waiter_unsafe.go
@@ -12,11 +12,6 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-// +build go1.11
-// +build !go1.17
-
-// Check go:linkname function signatures when updating Go version.
-
 package syncevent
 
 import (
@@ -26,17 +21,6 @@ import (
 	"gvisor.dev/gvisor/pkg/sync"
 )
 
-//go:linkname gopark runtime.gopark
-func gopark(unlockf func(unsafe.Pointer, *unsafe.Pointer) bool, wg *unsafe.Pointer, reason uint8, traceEv byte, traceskip int)
-
-//go:linkname goready runtime.goready
-func goready(g unsafe.Pointer, traceskip int)
-
-const (
-	waitReasonSelect     = 9  // Go: src/runtime/runtime2.go
-	traceEvGoBlockSelect = 24 // Go: src/runtime/trace.go
-)
-
 // Waiter allows a goroutine to block on pending events received by a Receiver.
 //
 // Waiter.Init() must be called before first use.
@@ -45,20 +29,19 @@ type Waiter struct {
 
 	// g is one of:
 	//
-	// - nil: No goroutine is blocking in Wait.
+	// - 0: No goroutine is blocking in Wait.
 	//
-	// - &preparingG: A goroutine is in Wait preparing to sleep, but hasn't yet
+	// - preparingG: A goroutine is in Wait preparing to sleep, but hasn't yet
 	// completed waiterUnlock(). Thus the wait can only be interrupted by
-	// replacing the value of g with nil (the G may not be in state Gwaiting
-	// yet, so we can't call goready.)
+	// replacing the value of g with 0 (the G may not be in state Gwaiting yet,
+	// so we can't call goready.)
 	//
 	// - Otherwise: g is a pointer to the runtime.g in state Gwaiting for the
 	// goroutine blocked in Wait, which can only be woken by calling goready.
-	g unsafe.Pointer `state:"zerovalue"`
+	g uintptr `state:"zerovalue"`
 }
 
-// Sentinel object for Waiter.g.
-var preparingG struct{}
+const preparingG = 1
 
 // Init must be called before first use of w.
 func (w *Waiter) Init() {
@@ -99,21 +82,29 @@ func (w *Waiter) WaitFor(es Set) Set {
 		}
 
 		// Indicate that we're preparing to go to sleep.
-		atomic.StorePointer(&w.g, (unsafe.Pointer)(&preparingG))
+		atomic.StoreUintptr(&w.g, preparingG)
 
 		// If an event is pending, abort the sleep.
 		if p := w.r.Pending(); p&es != NoEvents {
-			atomic.StorePointer(&w.g, nil)
+			atomic.StoreUintptr(&w.g, 0)
 			return p
 		}
 
 		// If w.g is still preparingG (i.e. w.NotifyPending() has not been
-		// called or has not reached atomic.SwapPointer()), go to sleep until
+		// called or has not reached atomic.SwapUintptr()), go to sleep until
 		// w.NotifyPending() => goready().
-		gopark(waiterUnlock, &w.g, waitReasonSelect, traceEvGoBlockSelect, 0)
+		sync.Gopark(waiterCommit, unsafe.Pointer(&w.g), sync.WaitReasonSelect, sync.TraceEvGoBlockSelect, 0)
 	}
 }
 
+//go:norace
+//go:nosplit
+func waiterCommit(g uintptr, wg unsafe.Pointer) bool {
+	// The only way this CAS can fail is if a call to Waiter.NotifyPending()
+	// has replaced *wg with nil, in which case we should not sleep.
+	return sync.RaceUncheckedAtomicCompareAndSwapUintptr((*uintptr)(wg), preparingG, g)
+}
+
 // Ack marks the given events as not pending.
 func (w *Waiter) Ack(es Set) {
 	w.r.Ack(es)
@@ -135,20 +126,20 @@ func (w *Waiter) WaitAndAckAll() Set {
 
 	for {
 		// Indicate that we're preparing to go to sleep.
-		atomic.StorePointer(&w.g, (unsafe.Pointer)(&preparingG))
+		atomic.StoreUintptr(&w.g, preparingG)
 
 		// If an event is pending, abort the sleep.
 		if w.r.Pending() != NoEvents {
 			if p := w.r.PendingAndAckAll(); p != NoEvents {
-				atomic.StorePointer(&w.g, nil)
+				atomic.StoreUintptr(&w.g, 0)
 				return p
 			}
 		}
 
 		// If w.g is still preparingG (i.e. w.NotifyPending() has not been
-		// called or has not reached atomic.SwapPointer()), go to sleep until
+		// called or has not reached atomic.SwapUintptr()), go to sleep until
 		// w.NotifyPending() => goready().
-		gopark(waiterUnlock, &w.g, waitReasonSelect, traceEvGoBlockSelect, 0)
+		sync.Gopark(waiterCommit, unsafe.Pointer(&w.g), sync.WaitReasonSelect, sync.TraceEvGoBlockSelect, 0)
 
 		// Check for pending events. We call PendingAndAckAll() directly now since
 		// we only expect to be woken after events become pending.
@@ -171,14 +162,14 @@ func (w *Waiter) NotifyPending() {
 	// goroutine. NotifyPending is called after w.r.Pending() is updated, so
 	// concurrent and future calls to w.Wait() will observe pending events and
 	// abort sleeping.
-	if atomic.LoadPointer(&w.g) == nil {
+	if atomic.LoadUintptr(&w.g) == 0 {
 		return
 	}
 	// Wake a sleeping G, or prevent a G that is preparing to sleep from doing
 	// so. Swap is needed here to ensure that only one call to NotifyPending
 	// calls goready.
-	if g := atomic.SwapPointer(&w.g, nil); g != nil && g != (unsafe.Pointer)(&preparingG) {
-		goready(g, 0)
+	if g := atomic.SwapUintptr(&w.g, 0); g > preparingG {
+		sync.Goready(g, 0)
 	}
 }