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