--- /dev/null	2018-04-03 12:55:20.301839954 +0200
+++ new/src/jdk.hotspot.agent/share/classes/sun/jvm/hotspot/gc/z/ZAddressRangeMapForPageTable.java	2018-06-08 19:46:52.523123199 +0200
@@ -0,0 +1,68 @@
+/*
+ * Copyright (c) 2018, Oracle and/or its affiliates. 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
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ *
+ */
+
+package sun.jvm.hotspot.gc.z;
+
+import sun.jvm.hotspot.debugger.Address;
+import sun.jvm.hotspot.runtime.VM;
+import sun.jvm.hotspot.runtime.VMObject;
+import sun.jvm.hotspot.types.AddressField;
+import sun.jvm.hotspot.types.Type;
+import sun.jvm.hotspot.types.TypeDataBase;
+
+public class ZAddressRangeMapForPageTable  extends VMObject {
+    private static AddressField mapField;
+
+    private static long AddressRangeShift = ZGlobals.ZPageSizeMinShift;
+
+    static {
+        VM.registerVMInitializedObserver((o, d) -> initialize(VM.getVM().getTypeDataBase()));
+    }
+
+    static private synchronized void initialize(TypeDataBase db) {
+        Type type = db.lookupType("ZAddressRangeMapForPageTable");
+
+        mapField = type.getAddressField("_map");
+    }
+
+    public ZAddressRangeMapForPageTable(Address addr) {
+        super(addr);
+    }
+
+    private Address map() {
+        return mapField.getValue(addr);
+    }
+
+    private long index_for_addr(Address addr) {
+        long index = ZAddress.offset(addr) >> AddressRangeShift;
+
+        return index;
+    }
+
+    Address get(Address addr) {
+        long index = index_for_addr(addr);
+
+        return map().getAddressAt(index * VM.getVM().getBytesPerLong());
+    }
+}