5 files changed, 61 insertions, 13 deletions
diff --git a/third_party/gvsync/BUILD b/third_party/gvsync/BUILD
index 4764eaa83..04a1fbeba 100644
--- a/third_party/gvsync/BUILD
+++ b/third_party/gvsync/BUILD
@@ -5,6 +5,8 @@ package(
     licenses = ["notice"],
 )
 
+exports_files(["LICENSE"])
+
 load("//tools/go_generics:defs.bzl", "go_template")
 
 go_template(
@@ -29,6 +31,8 @@ go_template(
 go_library(
     name = "gvsync",
     srcs = [
+        "downgradable_rwmutex_1_12_unsafe.go",
+        "downgradable_rwmutex_1_13_unsafe.go",
         "downgradable_rwmutex_unsafe.go",
         "gvsync.go",
         "memmove_unsafe.go",
diff --git a/third_party/gvsync/downgradable_rwmutex_1_12_unsafe.go b/third_party/gvsync/downgradable_rwmutex_1_12_unsafe.go
new file mode 100644
index 000000000..855b2a2b1
--- /dev/null
+++ b/third_party/gvsync/downgradable_rwmutex_1_12_unsafe.go
@@ -0,0 +1,21 @@
+// Copyright 2009 The Go Authors. All rights reserved.
+// 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 !go1.13
+
+// TODO(b/133868570): Delete once Go 1.12 is no longer supported.
+
+package gvsync
+
+import _ "unsafe"
+
+//go:linkname runtimeSemrelease112 sync.runtime_Semrelease
+func runtimeSemrelease112(s *uint32, handoff bool)
+
+func runtimeSemrelease(s *uint32, handoff bool, skipframes int) {
+	// 'skipframes' is only available starting from 1.13.
+	runtimeSemrelease112(s, handoff)
+}
diff --git a/third_party/gvsync/downgradable_rwmutex_1_13_unsafe.go b/third_party/gvsync/downgradable_rwmutex_1_13_unsafe.go
new file mode 100644
index 000000000..8baec5458
--- /dev/null
+++ b/third_party/gvsync/downgradable_rwmutex_1_13_unsafe.go
@@ -0,0 +1,16 @@
+// Copyright 2009 The Go Authors. All rights reserved.
+// 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 go1.13
+// +build !go1.14
+
+// Check go:linkname function signatures when updating Go version.
+
+package gvsync
+
+import _ "unsafe"
+
+//go:linkname runtimeSemrelease sync.runtime_Semrelease
+func runtimeSemrelease(s *uint32, handoff bool, skipframes int)
diff --git a/third_party/gvsync/downgradable_rwmutex_unsafe.go b/third_party/gvsync/downgradable_rwmutex_unsafe.go
index 4d43eb765..069939033 100644
--- a/third_party/gvsync/downgradable_rwmutex_unsafe.go
+++ b/third_party/gvsync/downgradable_rwmutex_unsafe.go
@@ -3,6 +3,11 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
+// +build go1.12
+// +build !go1.14
+
+// 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:
@@ -19,6 +24,9 @@ import (
 	"unsafe"
 )
 
+//go:linkname runtimeSemacquire sync.runtime_Semacquire
+func runtimeSemacquire(s *uint32)
+
 // DowngradableRWMutex is identical to sync.RWMutex, but adds the DowngradeLock
 // method.
 type DowngradableRWMutex struct {
@@ -62,7 +70,7 @@ func (rw *DowngradableRWMutex) RUnlock() {
 		// A writer is pending.
 		if atomic.AddInt32(&rw.readerWait, -1) == 0 {
 			// The last reader unblocks the writer.
-			runtimeSemrelease(&rw.writerSem, false)
+			runtimeSemrelease(&rw.writerSem, false, 0)
 		}
 	}
 	if RaceEnabled {
@@ -103,7 +111,7 @@ func (rw *DowngradableRWMutex) Unlock() {
 	}
 	// Unblock blocked readers, if any.
 	for i := 0; i < int(r); i++ {
-		runtimeSemrelease(&rw.readerSem, false)
+		runtimeSemrelease(&rw.readerSem, false, 0)
 	}
 	// Allow other writers to proceed.
 	rw.w.Unlock()
@@ -126,7 +134,7 @@ func (rw *DowngradableRWMutex) 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)
+		runtimeSemrelease(&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
@@ -136,9 +144,3 @@ func (rw *DowngradableRWMutex) DowngradeLock() {
 		RaceEnable()
 	}
 }
-
-//go:linkname runtimeSemacquire sync.runtime_Semacquire
-func runtimeSemacquire(s *uint32)
-
-//go:linkname runtimeSemrelease sync.runtime_Semrelease
-func runtimeSemrelease(s *uint32, handoff bool)
diff --git a/third_party/gvsync/memmove_unsafe.go b/third_party/gvsync/memmove_unsafe.go
index 4c8aa9ab6..84b69f215 100644
--- a/third_party/gvsync/memmove_unsafe.go
+++ b/third_party/gvsync/memmove_unsafe.go
@@ -3,12 +3,21 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
+// +build go1.12
+// +build !go1.14
+
+// Check go:linkname function signatures when updating Go version.
+
 package gvsync
 
 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
@@ -17,7 +26,3 @@ import (
 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)