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.runtime.VMObjectFactory;
  31 import sun.jvm.hotspot.types.CIntegerField;
  32 import sun.jvm.hotspot.types.Type;
  33 import sun.jvm.hotspot.types.TypeDataBase;
  34 
  35 public class ZPage extends VMObject {
  36     private static CIntegerField typeField;
  37     private static long virtualFieldOffset;
  38     private static CIntegerField topField;
  39     private static CIntegerField refcountField;
  40     private static long forwardingFieldOffset;
  41 
  42     static {
  43         VM.registerVMInitializedObserver((o, d) -> initialize(VM.getVM().getTypeDataBase()));
  44     }
  45 
  46     static private synchronized void initialize(TypeDataBase db) {
  47         Type type = db.lookupType("ZPage");
  48 
  49         typeField = type.getCIntegerField("_type");
  50         virtualFieldOffset = type.getField("_virtual").getOffset();
  51         topField = type.getCIntegerField("_top");
  52         refcountField = type.getCIntegerField("_refcount");
  53         forwardingFieldOffset = type.getField("_forwarding").getOffset();
  54     }
  55 
  56     public ZPage(Address addr) {
  57         super(addr);
  58     }
  59 
  60     private byte type() {
  61         return typeField.getJByte(addr);
  62     }
  63 
  64     private ZVirtualMemory virtual() {
  65         return (ZVirtualMemory)VMObjectFactory.newObject(ZVirtualMemory.class, addr.addOffsetTo(virtualFieldOffset));
  66     }
  67 
  68     private ZForwardingTable forwarding() {
  69         return (ZForwardingTable)VMObjectFactory.newObject(ZForwardingTable.class, addr.addOffsetTo(forwardingFieldOffset));
  70     }
  71 
  72     public long start() {
  73         return virtual().start();
  74     }
  75 
  76     public long top() {
  77         return topField.getJLong(addr);
  78     }
  79 
  80     public int refcount() {
  81         return topField.getJInt(addr);
  82     }
  83 
  84     Address forward_object(Address from) {
  85         // Lookup address in forwarding table
  86         long from_offset = ZAddress.offset(from);
  87         long from_index = (from_offset - start()) >> object_alignment_shift();
  88         ZForwardingTableEntry entry = forwarding().find(from_index);
  89         assert(!entry.is_empty());
  90         assert(entry.from_index() == from_index);
  91 
  92         return ZAddress.good(entry.to_offset());
  93     }
  94 
  95     Address relocate_object(Address from) {
  96         // Lookup address in forwarding table
  97         long from_offset = ZAddress.offset(from);
  98         long from_index = (from_offset - start()) >> object_alignment_shift();
  99         ZForwardingTableEntry entry = forwarding().find(from_index);
 100         if (!entry.is_empty() && entry.from_index() == from_index) {
 101           return ZAddress.good(entry.to_offset());
 102         }
 103 
 104         // There's no relocate operation in the SA.
 105         // Mimic object pinning and return the good view of the from object.
 106         return ZAddress.good(from);
 107     }
 108 
 109 
 110     long object_alignment_shift() {
 111         if (type() == ZGlobals.ZPageTypeSmall) {
 112             return ZGlobals.ZObjectAlignmentSmallShift();
 113         } else if (type() == ZGlobals.ZPageTypeMedium) {
 114             return ZGlobals.ZObjectAlignmentMediumShift;
 115         } else {
 116             assert(type() == ZGlobals.ZPageTypeLarge);
 117             return ZGlobals.ZObjectAlignmentLargeShift;
 118         }
 119     }
 120 }
--- EOF ---