--- a/src/hotspot/share/runtime/os.hpp	Thu Jul 19 09:46:29 2018 -0700
+++ b/src/hotspot/share/runtime/os.hpp	Thu Jul 19 10:17:22 2018 -0700
@@ -412,6 +412,9 @@
   static void    make_polling_page_unreadable();
   static void    make_polling_page_readable();
 
+  // Check if pointer points to readable memory (by 4-byte read access)
+  static bool    is_readable_pointer(const void* p);
+
   // Routines used to serialize the thread state without using membars
   static void    serialize_thread_states();