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.CIntegerField; 31 import sun.jvm.hotspot.types.Type; 32 import sun.jvm.hotspot.types.TypeDataBase; 33 34 class ZPage extends VMObject { 35 private static CIntegerField typeField; 36 private static long virtualFieldOffset; 37 private static long forwardingFieldOffset; 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("ZPage"); 45 46 typeField = type.getCIntegerField("_type"); 47 virtualFieldOffset = type.getField("_virtual").getOffset(); 48 forwardingFieldOffset = type.getField("_forwarding").getOffset(); 49 } 50 51 ZPage(Address addr) { 52 super(addr); 53 } 54 55 private byte type() { 56 return typeField.getJByte(addr); 57 } 58 59 private ZVirtualMemory virtual() { 60 return new ZVirtualMemory(addr.addOffsetTo(virtualFieldOffset)); 61 } 62 63 private ZForwardingTable forwarding() { 64 return new ZForwardingTable(addr.addOffsetTo(forwardingFieldOffset)); 65 } 66 67 private long start() { 68 return virtual().start(); 69 } 70 71 Address forward_object(Address from) { 72 // Lookup address in forwarding table 73 long from_offset = ZAddress.offset(from); 74 long from_index = (from_offset - start()) >> object_alignment_shift(); 75 ZForwardingTableEntry entry = forwarding().find(from_index); 76 assert(!entry.is_empty()); 77 assert(entry.from_index() == from_index); 78 79 return ZAddress.good(entry.to_offset()); 80 } 81 82 Address relocate_object(Address from) { 83 // Lookup address in forwarding table 84 long from_offset = ZAddress.offset(from); 85 long from_index = (from_offset - start()) >> object_alignment_shift(); 86 ZForwardingTableEntry entry = forwarding().find(from_index); 87 if (!entry.is_empty() && entry.from_index() == from_index) { 88 return ZAddress.good(entry.to_offset()); 89 } 90 91 // There's no relocate operation in the SA. Simply use the from address and hope for the best. 92 return from; 93 } 94 95 96 long object_alignment_shift() { 97 switch (type()) { 98 case ZGlobals.ZPageTypeSmall: 99 return ZGlobals.ZObjectAlignmentSmallShift(); 100 101 case ZGlobals.ZPageTypeMedium: 102 return ZGlobals.ZObjectAlignmentMediumShift; 103 104 default: 105 assert(type() == ZGlobals.ZPageTypeLarge); 106 return ZGlobals.ZObjectAlignmentLargeShift; 107 } 108 } 109 }