1 /*
2 * Copyright (c) 2018, 2019, 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 java.util.ArrayList;
28 import java.util.List;
29
30 import sun.jvm.hotspot.debugger.Address;
31 import sun.jvm.hotspot.debugger.OopHandle;
32 import sun.jvm.hotspot.gc.shared.LiveRegionsProvider;
33 import sun.jvm.hotspot.memory.MemRegion;
34 import sun.jvm.hotspot.oops.Oop;
35 import sun.jvm.hotspot.oops.UnknownOopException;
36 import sun.jvm.hotspot.runtime.VM;
37 import sun.jvm.hotspot.runtime.VMObject;
38 import sun.jvm.hotspot.runtime.VMObjectFactory;
39 import sun.jvm.hotspot.types.AddressField;
40 import sun.jvm.hotspot.types.CIntegerField;
41 import sun.jvm.hotspot.types.Type;
42 import sun.jvm.hotspot.types.TypeDataBase;
43
44 public class ZPage extends VMObject implements LiveRegionsProvider {
45 private static CIntegerField typeField;
46 private static CIntegerField seqnumField;
47 private static long virtualFieldOffset;
48 private static AddressField topField;
49 private static CIntegerField refcountField;
50 private static long forwardingFieldOffset;
51
52 static {
53 VM.registerVMInitializedObserver((o, d) -> initialize(VM.getVM().getTypeDataBase()));
54 }
55
56 static private synchronized void initialize(TypeDataBase db) {
57 Type type = db.lookupType("ZPage");
58
59 typeField = type.getCIntegerField("_type");
60 seqnumField = type.getCIntegerField("_seqnum");
61 virtualFieldOffset = type.getField("_virtual").getOffset();
62 topField = type.getAddressField("_top");
63 refcountField = type.getCIntegerField("_refcount");
64 forwardingFieldOffset = type.getField("_forwarding").getOffset();
65 }
66
67 public ZPage(Address addr) {
68 super(addr);
69 }
70
71 private byte type() {
72 return typeField.getJByte(addr);
73 }
74
75 private int seqnum() {
76 return seqnumField.getJInt(addr);
77 }
78
79 private ZVirtualMemory virtual() {
80 return VMObjectFactory.newObject(ZVirtualMemory.class, addr.addOffsetTo(virtualFieldOffset));
81 }
82
83 private Address top() {
84 return topField.getValue(addr);
85 }
86
87 private int refcount() {
88 // refcount is uint32_t so need to be cautious when using this field.
89 return refcountField.getJInt(addr);
90 }
91
92 private ZForwardingTable forwarding() {
93 return VMObjectFactory.newObject(ZForwardingTable.class, addr.addOffsetTo(forwardingFieldOffset));
94 }
95
96 private boolean is_forwarding() {
97 return forwarding().table() != null;
98 }
99
100 private boolean is_relocatable() {
101 return is_active() && seqnum() < ZGlobals.ZGlobalSeqNum();
102 }
103
104 private boolean isPageRelocating() {
105 assert(is_active());
106 // is_forwarding(): Has a (relocation) forwarding table
107 // is_relocatable(): Has not been freed yet
108 return is_forwarding() && is_relocatable();
109 }
110
111 long start() {
112 return virtual().start();
113 }
114
115 long size() {
116 return virtual().end() - virtual().start();
117 }
118
119 Address forward_object(Address from) {
120 // Lookup address in forwarding table
121 long from_offset = ZAddress.offset(from);
122 long from_index = (from_offset - start()) >> object_alignment_shift();
123 ZForwardingTableEntry entry = forwarding().find(from_index);
124 assert(!entry.is_empty());
125 assert(entry.from_index() == from_index);
126
127 return ZAddress.good(entry.to_offset());
128 }
129
130 Address relocate_object(Address from) {
131 // Lookup address in forwarding table
132 long from_offset = ZAddress.offset(from);
133 long from_index = (from_offset - start()) >> object_alignment_shift();
134 ZForwardingTableEntry entry = forwarding().find(from_index);
135 if (!entry.is_empty() && entry.from_index() == from_index) {
136 return ZAddress.good(entry.to_offset());
137 }
138
139 // There's no relocate operation in the SA.
140 // Mimic object pinning and return the good view of the from object.
141 return ZAddress.good(from);
142 }
143
144 long object_alignment_shift() {
145 if (type() == ZGlobals.ZPageTypeSmall) {
146 return ZGlobals.ZObjectAlignmentSmallShift();
147 } else if (type() == ZGlobals.ZPageTypeMedium) {
148 return ZGlobals.ZObjectAlignmentMediumShift;
149 } else {
150 assert(type() == ZGlobals.ZPageTypeLarge);
151 return ZGlobals.ZObjectAlignmentLargeShift;
152 }
153 }
154
155 long objectAlignmentSize() {
156 return 1 << object_alignment_shift();
157 }
158
159 public boolean is_active() {
160 return refcount() != 0;
161 }
162
163 private long getObjectSize(Address good) {
164 OopHandle handle = good.addOffsetToAsOopHandle(0);
165 Oop obj = null;
166
167 try {
168 obj = VM.getVM().getObjectHeap().newOop(handle);
169 } catch (UnknownOopException exp) {
170 throw new RuntimeException(" UnknownOopException " + exp);
171 }
172
173 return VM.getVM().alignUp(obj.getObjectSize(), objectAlignmentSize());
174 }
175
176 private void addNotRelocatedRegions(List<MemRegion> regions) {
177 MemRegion mr = null;
178
179 // Some objects have already been forwarded to new locations.
180 long topValue = top().asLongValue();
181 for (long offsetValue = start(); offsetValue < topValue;) {
182 Address from = ZAddress.good(ZUtils.longToAddress(offsetValue));
183
184 Address to = relocate_object(from);
185
186 long byteSize;
187 try {
188 byteSize = getObjectSize(to);
189 } catch (Exception e) {
190 // Parsing the ZHeap is inherently unsafe
191 // when classes have been unloaded. Dead objects
192 // might have stale Klass pointers, and there's
193 // no way to get the size of the dead object.
194 //
195 // If possible, run with -XX:-ClassUnloading
196 // to ensure that all Klasses are kept alive.
197 System.err.println("Unparsable regions found. Skipping: "
198 + from
199 + " "
200 + from.addOffsetTo(topValue - offsetValue));
201
202 // Can't proceed further. Just return the collected regions.
203 return;
204 }
205
206 if (from.equals(to)) {
207 // Not relocated - add region
208 if (mr == null) {
209 mr = new MemRegion(from, 0 /* wordSize */);
210 regions.add(mr);
211 }
212
213 long wordSize = byteSize / VM.getVM().getBytesPerWord();
214 mr.setWordSize(mr.wordSize() + wordSize);
215 } else {
216 // Forwarded somewhere else, split region.
217 mr = null;
218 }
219
220 offsetValue += byteSize;
221 }
222 }
223
224 public List<MemRegion> getLiveRegions() {
225 List<MemRegion> res = new ArrayList<>();
226
227 if (isPageRelocating()) {
228 addNotRelocatedRegions(res);
229 } else {
230 Address start = ZAddress.good(ZUtils.longToAddress(start()));
231
232 // Can't convert top() to a "good" address because it might
233 // be at the top of the "offset" range, and therefore also
234 // looks like one of the color bits. Instead use the "good"
235 // address and add the size.
236 long size = top().asLongValue() - start();
237 Address end = start.addOffsetTo(size);
238
239 res.add(new MemRegion(start, end));
240 }
241
242 return res;
243 }
244 }