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