8266453: Shenandoah: Disable write protections before patching nmethod in nmethod_barrier on MacOSX/AArch64

Reviewed-by: rkennke

Author: zhengyu123

src/hotspot/share/gc/shenandoah/shenandoahBarrierSetNMethod.cpp

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2019, Red Hat, Inc. All rights reserved.
+ * Copyright (c) 2019, 2021, Red Hat, Inc. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -33,6 +33,7 @@
 #include "gc/shenandoah/shenandoahThreadLocalData.hpp"
 #include "memory/iterator.hpp"
 #include "memory/resourceArea.hpp"
+#include "runtime/threadWXSetters.inline.hpp"
 
 bool ShenandoahBarrierSetNMethod::nmethod_entry_barrier(nmethod* nm) {
   ShenandoahReentrantLock* lock = ShenandoahNMethod::lock_for_nmethod(nm);
@@ -45,6 +46,8 @@ bool ShenandoahBarrierSetNMethod::nmethod_entry_barrier(nmethod* nm) {
     return true;
   }
 
+  MACOS_AARCH64_ONLY(ThreadWXEnable wx(WXWrite, Thread::current());)
+
   if (nm->is_unloading()) {
     // We don't need to take the lock when unlinking nmethods from
     // the Method, because it is only concurrently unlinked by