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 }