1 /*
2 * Copyright (c) 2024, 2025, 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.
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23 */
24
25 #include "cds/aotClassInitializer.hpp"
26 #include "cds/aotClassLinker.hpp"
27 #include "cds/aotLinkedClassBulkLoader.hpp"
28 #include "cds/aotLinkedClassTable.hpp"
29 #include "cds/cdsConfig.hpp"
30 #include "cds/heapShared.hpp"
31 #include "classfile/classLoaderData.hpp"
32 #include "classfile/classLoaderDataShared.hpp"
33 #include "classfile/javaClasses.hpp"
34 #include "classfile/systemDictionary.hpp"
35 #include "classfile/systemDictionaryShared.hpp"
36 #include "classfile/vmClasses.hpp"
37 #include "compiler/compilationPolicy.hpp"
38 #include "gc/shared/gcVMOperations.hpp"
39 #include "memory/resourceArea.hpp"
40 #include "oops/instanceKlass.hpp"
41 #include "oops/klass.inline.hpp"
42 #include "oops/trainingData.hpp"
43 #include "runtime/handles.inline.hpp"
44 #include "runtime/java.hpp"
45 #include "runtime/serviceThread.hpp"
46 #include "utilities/growableArray.hpp"
47
48 void AOTLinkedClassBulkLoader::serialize(SerializeClosure* soc) {
49 AOTLinkedClassTable::get()->serialize(soc);
50 }
51
52 // This function is called before the VM executes any Java code (include AOT-compiled Java methods).
53 //
54 // We populate the boot/platform/app class loaders with classes from the AOT cache. This is a fundamental
55 // step in restoring the JVM's state from the snapshot recorded in the AOT cache: other AOT optimizations
56 // such as AOT compiled methods can make direct references to the preloaded classes, knowing that
57 // these classes are guaranteed to be in at least the "loaded" state.
58 //
59 // Note: we can't link the classes yet because SharedRuntime is not yet ready to generate adapters.
60 void AOTLinkedClassBulkLoader::preload_classes(JavaThread* current) {
61 preload_classes_impl(current);
62 if (current->has_pending_exception()) {
63 exit_on_exception(current);
64 }
65 }
66
67 void AOTLinkedClassBulkLoader::preload_classes_impl(TRAPS) {
68 precond(CDSConfig::is_using_aot_linked_classes());
69
70 ClassLoaderDataShared::restore_archived_modules_for_preloading_classes(THREAD);
71 Handle h_platform_loader(THREAD, SystemDictionary::java_platform_loader());
72 Handle h_system_loader(THREAD, SystemDictionary::java_system_loader());
73
74 AOTLinkedClassTable* table = AOTLinkedClassTable::get();
75
76 preload_classes_in_table(table->boot1(), "boot1", Handle(), CHECK);
77 preload_classes_in_table(table->boot2(), "boot2", Handle(), CHECK);
78
79 initiate_loading(THREAD, "plat", h_platform_loader, table->boot1());
80 initiate_loading(THREAD, "plat", h_platform_loader, table->boot2());
81 preload_classes_in_table(table->platform(), "plat", h_platform_loader, CHECK);
82
83 initiate_loading(THREAD, "app", h_system_loader, table->boot1());
84 initiate_loading(THREAD, "app", h_system_loader, table->boot2());
85 initiate_loading(THREAD, "app", h_system_loader, table->platform());
86 preload_classes_in_table(table->app(), "app", h_system_loader, CHECK);
87 }
88
89 void AOTLinkedClassBulkLoader::preload_classes_in_table(Array<InstanceKlass*>* classes,
90 const char* category_name, Handle loader, TRAPS) {
91 if (classes == nullptr) {
92 return;
93 }
94
95 for (int i = 0; i < classes->length(); i++) {
96 InstanceKlass* ik = classes->at(i);
97 if (log_is_enabled(Info, aot, load)) {
98 ResourceMark rm(THREAD);
99 log_info(aot, load)("%-5s %s%s", category_name, ik->external_name(),
100 ik->is_hidden() ? " (hidden)" : "");
101 }
102
103 SystemDictionary::preload_class(loader, ik, CHECK);
104
105 if (ik->is_hidden()) {
106 DEBUG_ONLY({
107 // Make sure we don't make this hidden class available by name, even if we don't
108 // use any special ClassLoaderData.
109 ResourceMark rm(THREAD);
110 assert(SystemDictionary::find_instance_klass(THREAD, ik->name(), loader) == nullptr,
111 "hidden classes cannot be accessible by name: %s", ik->external_name());
112 });
113 } else {
114 precond(SystemDictionary::find_instance_klass(THREAD, ik->name(), loader) == ik);
115 }
116 }
117 }
118
119 // Some cached heap objects may hold references to methods in aot-linked
120 // classes (via MemberName). We need to make sure all classes are
121 // linked before executing any bytecode.
122 void AOTLinkedClassBulkLoader::link_classes(JavaThread* current) {
123 link_classes_impl(current);
124 if (current->has_pending_exception()) {
125 exit_on_exception(current);
126 }
127 }
128
129 void AOTLinkedClassBulkLoader::link_classes_impl(TRAPS) {
130 precond(CDSConfig::is_using_aot_linked_classes());
131
132 AOTLinkedClassTable* table = AOTLinkedClassTable::get();
133
134 link_classes_in_table(table->boot1(), CHECK);
135 link_classes_in_table(table->boot2(), CHECK);
136 link_classes_in_table(table->platform(), CHECK);
137 link_classes_in_table(table->app(), CHECK);
138 }
139
140 void AOTLinkedClassBulkLoader::link_classes_in_table(Array<InstanceKlass*>* classes, TRAPS) {
141 if (classes != nullptr) {
142 for (int i = 0; i < classes->length(); i++) {
143 // NOTE: CDSConfig::is_preserving_verification_constraints() is required
144 // when storing ik in the AOT cache. This means we don't have to verify
145 // ik at all.
146 //
147 // Without is_preserving_verification_constraints(), ik->link_class() may cause
148 // class loading, which may result in invocation of ClassLoader::loadClass() calls,
149 // which CANNOT happen because we are not ready to execute any Java byecodes yet
150 // at this point.
151 InstanceKlass* ik = classes->at(i);
152 ik->link_class(CHECK);
153 }
154 }
155 }
156
157 #ifdef ASSERT
158 void AOTLinkedClassBulkLoader::validate_module_of_preloaded_classes() {
159 oop javabase_module_oop = ModuleEntryTable::javabase_moduleEntry()->module_oop();
160 for (int i = T_BOOLEAN; i < T_LONG+1; i++) {
161 TypeArrayKlass* tak = Universe::typeArrayKlass((BasicType)i);
162 validate_module(tak, "boot1", javabase_module_oop);
163 }
164
165 JavaThread* current = JavaThread::current();
166 Handle h_platform_loader(current, SystemDictionary::java_platform_loader());
167 Handle h_system_loader(current, SystemDictionary::java_system_loader());
168 AOTLinkedClassTable* table = AOTLinkedClassTable::get();
169
170 validate_module_of_preloaded_classes_in_table(table->boot1(), "boot1", Handle());
171 validate_module_of_preloaded_classes_in_table(table->boot2(), "boot2", Handle());
172 validate_module_of_preloaded_classes_in_table(table->platform(), "plat", h_platform_loader);
173 validate_module_of_preloaded_classes_in_table(table->app(), "app", h_system_loader);
174 }
175
176 void AOTLinkedClassBulkLoader::validate_module_of_preloaded_classes_in_table(Array<InstanceKlass*>* classes,
177 const char* category_name, Handle loader) {
178 if (classes == nullptr) {
179 return;
180 }
181
182 ClassLoaderData* loader_data = ClassLoaderData::class_loader_data(loader());
183 for (int i = 0; i < classes->length(); i++) {
184 InstanceKlass* ik = classes->at(i);
185 PackageEntry* pkg_entry = ik->package();
186 oop module_oop;
187 if (pkg_entry == nullptr) {
188 module_oop = loader_data->unnamed_module()->module_oop();
189 } else {
190 module_oop = pkg_entry->module()->module_oop();
191 }
192
193 validate_module(ik, category_name, module_oop);
194 }
195 }
196
197 void AOTLinkedClassBulkLoader::validate_module(Klass* k, const char* category_name, oop module_oop) {
198 assert(module_oop != nullptr, "module system must have been initialized");
199
200 if (log_is_enabled(Debug, aot, module)) {
201 ResourceMark rm;
202 log_debug(aot, module)("Validate module of %-5s %s", category_name, k->external_name());
203 }
204 precond(java_lang_Class::module(k->java_mirror()) == module_oop);
205
206 ArrayKlass* ak = k->array_klass_or_null();
207 while (ak != nullptr) {
208 if (log_is_enabled(Debug, aot, module)) {
209 ResourceMark rm;
210 log_debug(aot, module)("Validate module of %-5s %s", category_name, ak->external_name());
211 }
212 precond(java_lang_Class::module(ak->java_mirror()) == module_oop);
213 ak = ak->array_klass_or_null();
214 }
215 }
216 #endif
217
218 void AOTLinkedClassBulkLoader::init_javabase_classes(JavaThread* current) {
219 init_classes_for_loader(Handle(), AOTLinkedClassTable::get()->boot1(), current);
220 if (current->has_pending_exception()) {
221 exit_on_exception(current);
222 }
223 }
224
225 void AOTLinkedClassBulkLoader::init_non_javabase_classes(JavaThread* current) {
226 init_non_javabase_classes_impl(current);
227 if (current->has_pending_exception()) {
228 exit_on_exception(current);
229 }
230 }
231
232 void AOTLinkedClassBulkLoader::init_non_javabase_classes_impl(TRAPS) {
233 assert(CDSConfig::is_using_aot_linked_classes(), "sanity");
234
235 DEBUG_ONLY(validate_module_of_preloaded_classes());
236
237 // is_using_aot_linked_classes() requires is_using_full_module_graph(). As a result,
238 // the platform/system class loader should already have been initialized as part
239 // of the FMG support.
240 assert(CDSConfig::is_using_full_module_graph(), "must be");
241
242 Handle h_platform_loader(THREAD, SystemDictionary::java_platform_loader());
243 Handle h_system_loader(THREAD, SystemDictionary::java_system_loader());
244
245 assert(h_platform_loader() != nullptr, "must be");
246 assert(h_system_loader() != nullptr, "must be");
247
248 AOTLinkedClassTable* table = AOTLinkedClassTable::get();
249 init_classes_for_loader(Handle(), table->boot2(), CHECK);
250 init_classes_for_loader(h_platform_loader, table->platform(), CHECK);
251 init_classes_for_loader(h_system_loader, table->app(), CHECK);
252
253 if (Universe::is_fully_initialized() && VerifyDuringStartup) {
254 // Make sure we're still in a clean state.
255 VM_Verify verify_op;
256 VMThread::execute(&verify_op);
257 }
258
259 if (AOTPrintTrainingInfo) {
260 tty->print_cr("==================== archived_training_data ** after all classes preloaded ====================");
261 TrainingData::print_archived_training_data_on(tty);
262 }
263 }
264
265 // For the AOT cache to function properly, all classes in the AOTLinkedClassTable
266 // must be loaded and linked. In addition, AOT-initialized classes must be moved to
267 // the initialized state.
268 //
269 // We can encounter a failure during the loading, linking, or initialization of
270 // classes in the AOTLinkedClassTable only if:
271 // - We ran out of memory,
272 // - There is a serious error in the VM implemenation
273 // When this happens, the VM may be in an inconsistent state (e.g., we have a cached
274 // heap object of class X, but X is not linked). We must exit the JVM now.
275
276 void AOTLinkedClassBulkLoader::exit_on_exception(JavaThread* current) {
277 assert(current->has_pending_exception(), "precondition");
278 ResourceMark rm(current);
279 if (current->pending_exception()->is_a(vmClasses::OutOfMemoryError_klass())) {
280 log_error(aot)("Out of memory. Please run with a larger Java heap, current MaxHeapSize = "
281 "%zuM", MaxHeapSize/M);
282 } else {
283 oop message = java_lang_Throwable::message(current->pending_exception());
284 log_error(aot)("%s: %s", current->pending_exception()->klass()->external_name(),
285 message == nullptr ? "(no message)" : java_lang_String::as_utf8_string(message));
286 }
287 vm_exit_during_initialization("Unexpected exception when loading aot-linked classes.");
288 }
289
290 // Initiate loading of the <classes> in the <initiating_loader>. The <classes> should have already been loaded
291 // by a parent loader of the <initiating_loader>. This is necessary for handling pre-resolved CP entries.
292 //
293 // For example, we initiate the loading of java/lang/String in the AppClassLoader. This will allow
294 // any App classes to have a pre-resolved ConstantPool entry that references java/lang/String.
295 //
296 // TODO: we can limit the number of initiated classes to only those that are actually referenced by
297 // AOT-linked classes loaded by <initiating_loader>.
298 void AOTLinkedClassBulkLoader::initiate_loading(JavaThread* current, const char* category_name,
299 Handle initiating_loader, Array<InstanceKlass*>* classes) {
300 if (classes == nullptr) {
301 return;
302 }
303
304 assert(initiating_loader() == SystemDictionary::java_platform_loader() ||
305 initiating_loader() == SystemDictionary::java_system_loader(), "must be");
306 ClassLoaderData* loader_data = ClassLoaderData::class_loader_data(initiating_loader());
307 MonitorLocker mu1(SystemDictionary_lock);
308
309 for (int i = 0; i < classes->length(); i++) {
310 InstanceKlass* ik = classes->at(i);
311 assert(ik->is_loaded(), "must have already been loaded by a parent loader");
312 assert(ik->class_loader() != initiating_loader(), "must be a parent loader");
313 assert(ik->class_loader() == nullptr ||
314 ik->class_loader() == SystemDictionary::java_platform_loader(), "must be");
315 if (ik->is_public() && !ik->is_hidden()) {
316 if (log_is_enabled(Info, aot, load)) {
317 ResourceMark rm(current);
318 const char* defining_loader = (ik->class_loader() == nullptr ? "boot" : "plat");
319 log_info(aot, load)("%-5s %s (initiated, defined by %s)", category_name, ik->external_name(),
320 defining_loader);
321 }
322 SystemDictionary::add_to_initiating_loader(current, ik, loader_data);
323 }
324 }
325 }
326
327 // Some AOT-linked classes for <class_loader> must be initialized early. This includes
328 // - classes that were AOT-initialized by AOTClassInitializer
329 // - the classes of all objects that are reachable from the archived mirrors of
330 // the AOT-linked classes for <class_loader>.
331 void AOTLinkedClassBulkLoader::init_classes_for_loader(Handle class_loader, Array<InstanceKlass*>* classes, TRAPS) {
332 if (classes != nullptr) {
333 for (int i = 0; i < classes->length(); i++) {
334 InstanceKlass* ik = classes->at(i);
335 assert(ik->class_loader_data() != nullptr, "must be");
336 if (ik->has_aot_initialized_mirror()) {
337 ik->initialize_with_aot_initialized_mirror(CHECK);
338 }
339 }
340 }
341
342 HeapShared::init_classes_for_special_subgraph(class_loader, CHECK);
343 }
344
345 void AOTLinkedClassBulkLoader::replay_training_at_init(Array<InstanceKlass*>* classes, TRAPS) {
346 if (classes != nullptr) {
347 for (int i = 0; i < classes->length(); i++) {
348 InstanceKlass* ik = classes->at(i);
349 if (ik->has_aot_initialized_mirror() && ik->is_initialized() && !ik->has_init_deps_processed()) {
350 CompilationPolicy::replay_training_at_init(ik, CHECK);
351 }
352 }
353 }
354 }
355
356 void AOTLinkedClassBulkLoader::replay_training_at_init_for_preloaded_classes(TRAPS) {
357 if (CDSConfig::is_using_aot_linked_classes() && TrainingData::have_data()) {
358 AOTLinkedClassTable* table = AOTLinkedClassTable::get();
359 replay_training_at_init(table->boot1(), CHECK);
360 replay_training_at_init(table->boot2(), CHECK);
361 replay_training_at_init(table->platform(), CHECK);
362 replay_training_at_init(table->app(), CHECK);
363 }
364 }