1 /*

     2  * Copyright (c) 2018, Oracle and/or its affiliates. All rights reserved.

     3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

     4  *

     5  * This code is free software; you can redistribute it and/or modify it

     6  * under the terms of the GNU General Public License version 2 only, as

     7  * published by the Free Software Foundation.

     8  *

     9  * This code is distributed in the hope that it will be useful, but WITHOUT

    10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

    11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

    12  * version 2 for more details (a copy is included in the LICENSE file that

    13  * accompanied this code).

    14  *

    15  * You should have received a copy of the GNU General Public License version

    16  * 2 along with this work; if not, write to the Free Software Foundation,

    17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

    18  *

    19  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

    20  * or visit www.oracle.com if you need additional information or have any

    21  * questions.

    22  *

    23  */

    24 

    25 package sun.jvm.hotspot.gc.z;

    26 

    27 import sun.jvm.hotspot.debugger.Address;

    28 import sun.jvm.hotspot.runtime.VM;

    29 import sun.jvm.hotspot.runtime.VMObject;

    30 import sun.jvm.hotspot.types.AddressField;

    31 import sun.jvm.hotspot.types.Type;

    32 import sun.jvm.hotspot.types.TypeDataBase;

    33 

    34 public class ZAddressRangeMapForPageTable  extends VMObject {

    35     private static AddressField mapField;

    36 

    37     private static long AddressRangeShift = ZGlobals.ZPageSizeMinShift;

    38 

    39     static {

    40         VM.registerVMInitializedObserver((o, d) -> initialize(VM.getVM().getTypeDataBase()));

    41     }

    42 

    43     static private synchronized void initialize(TypeDataBase db) {

    44         Type type = db.lookupType("ZAddressRangeMapForPageTable");

    45 

    46         mapField = type.getAddressField("_map");

    47     }

    48 

    49     public ZAddressRangeMapForPageTable(Address addr) {

    50         super(addr);

    51     }

    52 

    53     private Address map() {

    54         return mapField.getValue(addr);

    55     }

    56 

    57     private long index_for_addr(Address addr) {

    58         long index = ZAddress.offset(addr) >> AddressRangeShift;

    59 

    60         return index;

    61     }

    62 

    63     Address get(Address addr) {

    64         long index = index_for_addr(addr);

    65 

    66         return map().getAddressAt(index * VM.getVM().getBytesPerLong());

    67     }

    68 }