1 /*
2 * Copyright (c) 2018, 2026, 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.memory;
26
27 import java.util.*;
28 import sun.jvm.hotspot.debugger.Address;
29 import sun.jvm.hotspot.runtime.VM;
30 import sun.jvm.hotspot.runtime.VMObject;
31 import sun.jvm.hotspot.runtime.VMObjectFactory;
32 import sun.jvm.hotspot.types.*;
33 import sun.jvm.hotspot.utilities.Observable;
34 import sun.jvm.hotspot.utilities.Observer;
35
36 public class FileMapInfo {
37 private static FileMapHeader headerObj;
38
39 // Fields for handling the copied C++ vtables
40 private static Address rwRegionBaseAddress;
41 private static Address rwRegionEndAddress;
42 private static Address vtablesIndex;
43 private static Address mapped_base_address;
44
45 // HashMap created by mapping the vTable addresses in the rw region with
46 // the corresponding metadata type.
47 private static Map<Address, Type> vTableTypeMap;
48
49 private static Type metadataTypeArray[];
50
51 static {
52 VM.registerVMInitializedObserver(new Observer() {
53 public void update(Observable o, Object data) {
54 initialize(VM.getVM().getTypeDataBase());
55 }
56 });
57 }
58
59 static Address getStatic_AddressField(Type type, String fieldName) {
60 AddressField field = type.getAddressField(fieldName);
61 return field.getValue();
62 }
63
64 static Address get_AddressField(Type type, Address instance, String fieldName) {
65 AddressField field = type.getAddressField(fieldName);
66 return field.getValue(instance);
67 }
68
69 static long get_CIntegerField(Type type, Address instance, String fieldName) {
70 CIntegerField field = type.getCIntegerField(fieldName);
71 return field.getValue(instance);
72 }
73
74 // C equivalent: return &header->_regions[index];
75 static Address get_CDSFileMapRegion(Type FileMapHeader_type, Address header, int index) {
76 AddressField regionsField = FileMapHeader_type.getAddressField("_regions[0]");
77
78 // size_t offset = offsetof(FileMapHeader, _regions[0]);
79 // CDSFileMapRegion* regions_0 = ((char*)header) + offset; // regions_0 = &header->_regions[index];
80 // return ((char*)regions_0) + index * sizeof(CDSFileMapRegion);
81 long offset = regionsField.getOffset();
82 Address regions_0 = header.addOffsetTo(offset);
83 return regions_0.addOffsetTo(index * regionsField.getSize());
84 }
85
86 private static void initialize(TypeDataBase db) {
87 vTableTypeMap = null; // force vTableTypeMap to get re-initialized later
88
89 Type FileMapInfo_type = db.lookupType("FileMapInfo");
90 Type FileMapHeader_type = db.lookupType("FileMapHeader");
91 Type CDSFileMapRegion_type = db.lookupType("CDSFileMapRegion");
92
93 // FileMapInfo * info = FileMapInfo::_current_info;
94 // FileMapHeader* header = info->_header
95 Address info = getStatic_AddressField(FileMapInfo_type, "_current_info");
96 Address header = get_AddressField(FileMapInfo_type, info, "_header");
97 headerObj = VMObjectFactory.newObject(FileMapHeader.class, header);
98
99 // char* mapped_base_address = header->_mapped_base_address
100 // narrowPtr cloned_vtable_narrowPtr = header->_cloned_vtable_offset
101 // size_t cloned_vtable_offset = AOTCompressedPointers::get_byte_offset(cloned_vtable_narrowPtr);
102 // CppVtableInfo** vtablesIndex = mapped_base_address + cloned_vtable_offset;
103 mapped_base_address = get_AddressField(FileMapHeader_type, header, "_mapped_base_address");
104 long cloned_vtable_narrowPtr = get_CIntegerField(FileMapHeader_type, header, "_cloned_vtables");
105 long cloned_vtable_offset = cloned_vtable_narrowPtr; // Currently narrowPtr is the same as offset
106 vtablesIndex = mapped_base_address.addOffsetTo(cloned_vtable_offset);
107
108 // CDSFileMapRegion* rw_region = &header->_region[rw];
109 // char* rwRegionBaseAddress = rw_region->_mapped_base;
110 // size_t used = rw_region->_used;
111 // char* rwRegionEndAddress = rwRegionBaseAddress + used;
112 Address rw_region = get_CDSFileMapRegion(FileMapHeader_type, header, 0);
113 rwRegionBaseAddress = get_AddressField(CDSFileMapRegion_type, rw_region, "_mapped_base");
114 long used = get_CIntegerField(CDSFileMapRegion_type, rw_region, "_used");
115 rwRegionEndAddress = rwRegionBaseAddress.addOffsetTo(used);
116
117 populateMetadataTypeArray(db);
118 }
119
120 private static void populateMetadataTypeArray(TypeDataBase db) {
121 metadataTypeArray = new Type[11];
122 // The order needs to match up with CPP_VTABLE_TYPES_DO in src/hotspot/share/cds/cppVtables.cpp
123
124 metadataTypeArray[0] = db.lookupType("ConstantPool");
125 metadataTypeArray[1] = db.lookupType("InstanceKlass");
126 metadataTypeArray[2] = db.lookupType("InstanceClassLoaderKlass");
127 metadataTypeArray[3] = db.lookupType("InstanceMirrorKlass");
128 metadataTypeArray[4] = db.lookupType("InstanceRefKlass");
129 metadataTypeArray[5] = db.lookupType("InstanceStackChunkKlass");
130 metadataTypeArray[6] = db.lookupType("Method");
131 metadataTypeArray[7] = db.lookupType("MethodData");
132 metadataTypeArray[8] = db.lookupType("MethodCounters");
133 metadataTypeArray[9] = db.lookupType("ObjArrayKlass");
134 metadataTypeArray[10] = db.lookupType("TypeArrayKlass");
135 }
136
137 public FileMapHeader getHeader() {
138 return headerObj;
139 }
140
141 public boolean inCopiedVtableSpace(Address vptrAddress) {
142 FileMapHeader fmHeader = getHeader();
143 return fmHeader.inCopiedVtableSpace(vptrAddress);
144 }
145
146 public Type getTypeForVptrAddress(Address vptrAddress) {
147 if (vTableTypeMap == null) {
148 getHeader().createVtableTypeMapping();
149 }
150 return vTableTypeMap.get(vptrAddress);
151 }
152
153
154 //------------------------------------------------------------------------------------------
155
156 public static class FileMapHeader extends VMObject {
157
158 public FileMapHeader(Address addr) {
159 super(addr);
160 }
161
162 public boolean inCopiedVtableSpace(Address vptrAddress) {
163 if (vptrAddress == null) {
164 return false;
165 }
166 if (vptrAddress.greaterThan(rwRegionBaseAddress) &&
167 vptrAddress.lessThanOrEqual(rwRegionEndAddress)) {
168 return true;
169 }
170 return false;
171 }
172
173 public void createVtableTypeMapping() {
174 vTableTypeMap = new HashMap<Address, Type>();
175 long addressSize = VM.getVM().getAddressSize();
176
177 // vtablesIndex points to to an array like this:
178 // long info[] = {
179 // offset of the CppVtableInfo for ConstantPool,
180 // offset of the CppVtableInfo for InstanceKlass,
181 // offset of the CppVtableInfo for InstanceClassLoaderKlass,
182 // ...
183 // };
184 //
185 // class CppVtableInfo {
186 // intptr_t _vtable_size;
187 // intptr_t _cloned_vtable[1];
188 // ...
189 // };
190 //
191 // The loop below computes the following
192 // CppVtableInfo* t_ConstantPool = mapped_base_address + info[0];
193 // CppVtableInfo* t_InstanceKlass = mapped_base_address + info[1];
194 // ...
195 //
196 // If we have the following objects
197 // ConstantPool* cp = ....; // an archived constant pool
198 // InstanceKlass* ik = ....;// an archived class
199 //
200 // then the following holds true:
201 // ((intptr_t**)cp)[0] == &t_ConstantPool->_cloned_vtable[0] // The vtable for archived ConstantPools
202 // ((intptr_t**)ik)[0] == &t_InstanceKlass->_cloned_vtable[0] // The vtable for archived InstanceKlasses
203 //
204 // To get an idea what these address look like, do this:
205 //
206 // $ java -Xlog:cds+vtables=debug -XX:+UnlockDiagnosticVMOptions -XX:ArchiveRelocationMode=0 --version
207 // [0.002s][debug][cds,vtables] Copying 14 vtable entries for ConstantPool to 0x800000018
208 // [0.002s][debug][cds,vtables] Copying 41 vtable entries for InstanceKlass to 0x800000090
209 // [0.002s][debug][cds,vtables] Copying 41 vtable entries for InstanceClassLoaderKlass to 0x8000001e0
210 // [0.002s][debug][cds,vtables] Copying 41 vtable entries for InstanceMirrorKlass to 0x800000330
211 // [0.002s][debug][cds,vtables] Copying 41 vtable entries for InstanceRefKlass to 0x800000480
212 // [0.002s][debug][cds,vtables] Copying 41 vtable entries for InstanceStackChunkKlass to 0x8000005d0
213 // [0.002s][debug][cds,vtables] Copying 14 vtable entries for Method to 0x800000720
214 // [0.002s][debug][cds,vtables] Copying 42 vtable entries for ObjArrayKlass to 0x800000798
215 // [0.002s][debug][cds,vtables] Copying 42 vtable entries for TypeArrayKlass to 0x8000008f0
216 // java 23-internal 2024-09-17
217 // ...
218
219 for (int i=0; i < metadataTypeArray.length; i++) {
220 long vtable_offset = vtablesIndex.getJLongAt(i * addressSize); // long offset = _index[i]
221
222 // CppVtableInfo* t = the address of the CppVtableInfo for the i-th table
223 Address vtableInfoAddress = mapped_base_address.addOffsetTo(vtable_offset);
224
225 // vtableAddress = &t->_cloned_vtable[0]
226 Address vtableAddress = vtableInfoAddress.addOffsetTo(addressSize);
227
228 vTableTypeMap.put(vtableAddress, metadataTypeArray[i]);
229 }
230 }
231 }
232 }