1 files changed, 13 insertions, 0 deletions
diff --git a/src/runtime/export_test.go b/src/runtime/export_test.go
index 9b765550ca..3b33c8422b 100644
--- a/src/runtime/export_test.go
+++ b/src/runtime/export_test.go
@@ -245,3 +245,16 @@ func CountPagesInUse() (pagesInUse, counted uintptr) {
 
 	return
 }
+
+// BlockOnSystemStack switches to the system stack, prints "x\n" to
+// stderr, and blocks in a stack containing
+// "runtime.blockOnSystemStackInternal".
+func BlockOnSystemStack() {
+	systemstack(blockOnSystemStackInternal)
+}
+
+func blockOnSystemStackInternal() {
+	print("x\n")
+	lock(&deadlock)
+	lock(&deadlock)
+}