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.
22 *
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
46 void AOTLinkedClassBulkLoader::serialize(SerializeClosure* soc) {
47 AOTLinkedClassTable::get()->serialize(soc);
48 }
49
50 // This function is called before the VM executes any Java code (include AOT-compiled Java methods).
51 //
52 // We populate the boot/platform/app class loaders with classes from the AOT cache. This is a fundamental
53 // step in restoring the JVM's state from the snapshot recorded in the AOT cache: other AOT optimizations
54 // such as AOT compiled methods can make direct references to the preloaded classes, knowing that
55 // these classes are guaranteed to be in at least the "loaded" state.
56 void AOTLinkedClassBulkLoader::preload_classes(JavaThread* current) {
57 preload_classes_impl(current);
58 if (current->has_pending_exception()) {
59 exit_on_exception(current);
60 }
61 }
62
63 void AOTLinkedClassBulkLoader::preload_classes_impl(TRAPS) {
64 precond(CDSConfig::is_using_aot_linked_classes());
65
66 ClassLoaderDataShared::restore_archived_modules_for_preloading_classes(THREAD);
67 Handle h_platform_loader(THREAD, SystemDictionary::java_platform_loader());
68 Handle h_system_loader(THREAD, SystemDictionary::java_system_loader());
69
70 AOTLinkedClassTable* table = AOTLinkedClassTable::get();
71
72 preload_classes_in_table(table->boot1(), "boot1", Handle(), CHECK);
73 preload_classes_in_table(table->boot2(), "boot2", Handle(), CHECK);
74
75 initiate_loading(THREAD, "plat", h_platform_loader, table->boot1());
76 initiate_loading(THREAD, "plat", h_platform_loader, table->boot2());
77 preload_classes_in_table(table->platform(), "plat", h_platform_loader, CHECK);
78
79 initiate_loading(THREAD, "app", h_system_loader, table->boot1());
80 initiate_loading(THREAD, "app", h_system_loader, table->boot2());
81 initiate_loading(THREAD, "app", h_system_loader, table->platform());
82 preload_classes_in_table(table->app(), "app", h_system_loader, CHECK);
83 }
84
85 void AOTLinkedClassBulkLoader::preload_classes_in_table(Array<InstanceKlass*>* classes,
86 const char* category_name, Handle loader, TRAPS) {
87 if (classes == nullptr) {
88 return;
89 }
90
91 for (int i = 0; i < classes->length(); i++) {
92 InstanceKlass* ik = classes->at(i);
93 if (log_is_enabled(Info, aot, load)) {
94 ResourceMark rm(THREAD);
95 log_info(aot, load)("%-5s %s%s", category_name, ik->external_name(),
96 ik->is_hidden() ? " (hidden)" : "");
97 }
98
99 SystemDictionary::preload_class(loader, ik, CHECK);
100
101 if (ik->is_hidden()) {
102 DEBUG_ONLY({
103 // Make sure we don't make this hidden class available by name, even if we don't
104 // use any special ClassLoaderData.
105 ResourceMark rm(THREAD);
106 assert(SystemDictionary::find_instance_klass(THREAD, ik->name(), loader) == nullptr,
107 "hidden classes cannot be accessible by name: %s", ik->external_name());
108 });
109 } else {
110 precond(SystemDictionary::find_instance_klass(THREAD, ik->name(), loader) == ik);
111 }
112 }
113 }
114
115 #ifdef ASSERT
116 void AOTLinkedClassBulkLoader::validate_module_of_preloaded_classes() {
117 oop javabase_module_oop = ModuleEntryTable::javabase_moduleEntry()->module_oop();
118 for (int i = T_BOOLEAN; i < T_LONG+1; i++) {
119 TypeArrayKlass* tak = Universe::typeArrayKlass((BasicType)i);
120 validate_module(tak, "boot1", javabase_module_oop);
121 }
122
123 JavaThread* current = JavaThread::current();
124 Handle h_platform_loader(current, SystemDictionary::java_platform_loader());
125 Handle h_system_loader(current, SystemDictionary::java_system_loader());
126 AOTLinkedClassTable* table = AOTLinkedClassTable::get();
127
128 validate_module_of_preloaded_classes_in_table(table->boot1(), "boot1", Handle());
129 validate_module_of_preloaded_classes_in_table(table->boot2(), "boot2", Handle());
130 validate_module_of_preloaded_classes_in_table(table->platform(), "plat", h_platform_loader);
131 validate_module_of_preloaded_classes_in_table(table->app(), "app", h_system_loader);
132 }
133
134 void AOTLinkedClassBulkLoader::validate_module_of_preloaded_classes_in_table(Array<InstanceKlass*>* classes,
135 const char* category_name, Handle loader) {
136 if (classes == nullptr) {
137 return;
138 }
139
140 ClassLoaderData* loader_data = ClassLoaderData::class_loader_data(loader());
141 for (int i = 0; i < classes->length(); i++) {
142 InstanceKlass* ik = classes->at(i);
143 PackageEntry* pkg_entry = ik->package();
144 oop module_oop;
145 if (pkg_entry == nullptr) {
146 module_oop = loader_data->unnamed_module()->module_oop();
147 } else {
148 module_oop = pkg_entry->module()->module_oop();
149 }
150
151 validate_module(ik, category_name, module_oop);
152 }
153 }
154
155 void AOTLinkedClassBulkLoader::validate_module(Klass* k, const char* category_name, oop module_oop) {
156 assert(module_oop != nullptr, "module system must have been initialized");
157
158 if (log_is_enabled(Debug, aot, module)) {
159 ResourceMark rm;
160 log_debug(aot, module)("Validate module of %-5s %s", category_name, k->external_name());
161 }
162 precond(java_lang_Class::module(k->java_mirror()) == module_oop);
163
164 ArrayKlass* ak = k->array_klass_or_null();
165 while (ak != nullptr) {
166 if (log_is_enabled(Debug, aot, module)) {
167 ResourceMark rm;
168 log_debug(aot, module)("Validate module of %-5s %s", category_name, ak->external_name());
169 }
170 precond(java_lang_Class::module(ak->java_mirror()) == module_oop);
171 ak = ak->array_klass_or_null();
172 }
173 }
174 #endif
175
176 // Link all java.base classes in the AOTLinkedClassTable. Of those classes,
177 // move the ones that have been AOT-initialized to the "initialized" state.
178 void AOTLinkedClassBulkLoader::link_or_init_javabase_classes(JavaThread* current) {
179 link_or_init_classes_for_loader(Handle(), AOTLinkedClassTable::get()->boot1(), current);
180 if (current->has_pending_exception()) {
181 exit_on_exception(current);
182 }
183 }
184
185 // Do the same thing as link_or_init_javabase_classes(), but for the classes that are not
186 // in the java.base module.
187 void AOTLinkedClassBulkLoader::link_or_init_non_javabase_classes(JavaThread* current) {
188 link_or_init_non_javabase_classes_impl(current);
189 if (current->has_pending_exception()) {
190 exit_on_exception(current);
191 }
192 }
193
194 void AOTLinkedClassBulkLoader::link_or_init_non_javabase_classes_impl(TRAPS) {
195 assert(CDSConfig::is_using_aot_linked_classes(), "sanity");
196
197 DEBUG_ONLY(validate_module_of_preloaded_classes());
198
199 // is_using_aot_linked_classes() requires is_using_full_module_graph(). As a result,
200 // the platform/system class loader should already have been initialized as part
201 // of the FMG support.
202 assert(CDSConfig::is_using_full_module_graph(), "must be");
203
204 Handle h_platform_loader(THREAD, SystemDictionary::java_platform_loader());
205 Handle h_system_loader(THREAD, SystemDictionary::java_system_loader());
206
207 assert(h_platform_loader() != nullptr, "must be");
208 assert(h_system_loader() != nullptr, "must be");
209
210 AOTLinkedClassTable* table = AOTLinkedClassTable::get();
211 link_or_init_classes_for_loader(Handle(), table->boot2(), CHECK);
212 link_or_init_classes_for_loader(h_platform_loader, table->platform(), CHECK);
213 link_or_init_classes_for_loader(h_system_loader, table->app(), CHECK);
214
215 if (Universe::is_fully_initialized() && VerifyDuringStartup) {
216 // Make sure we're still in a clean state.
217 VM_Verify verify_op;
218 VMThread::execute(&verify_op);
219 }
220
221 if (AOTPrintTrainingInfo) {
222 tty->print_cr("==================== archived_training_data ** after all classes preloaded ====================");
223 TrainingData::print_archived_training_data_on(tty);
224 }
225 }
226
227 // For the AOT cache to function properly, all classes in the AOTLinkedClassTable
228 // must be loaded and linked. In addition, AOT-initialized classes must be moved to
229 // the initialized state.
230 //
231 // We can encounter a failure during the loading, linking, or initialization of
232 // classes in the AOTLinkedClassTable only if:
233 // - We ran out of memory,
234 // - There is a serious error in the VM implemenation
235 // When this happens, the VM may be in an inconsistent state (e.g., we have a cached
236 // heap object of class X, but X is not linked). We must exit the JVM now.
237
238 void AOTLinkedClassBulkLoader::exit_on_exception(JavaThread* current) {
239 assert(current->has_pending_exception(), "precondition");
240 ResourceMark rm(current);
241 if (current->pending_exception()->is_a(vmClasses::OutOfMemoryError_klass())) {
242 log_error(aot)("Out of memory. Please run with a larger Java heap, current MaxHeapSize = "
243 "%zuM", MaxHeapSize/M);
244 } else {
245 log_error(aot)("%s: %s", current->pending_exception()->klass()->external_name(),
246 java_lang_String::as_utf8_string(java_lang_Throwable::message(current->pending_exception())));
247 }
248 vm_exit_during_initialization("Unexpected exception when loading aot-linked classes.");
249 }
250
251 // Initiate loading of the <classes> in the <initiating_loader>. The <classes> should have already been loaded
252 // by a parent loader of the <initiating_loader>. This is necessary for handling pre-resolved CP entries.
253 //
254 // For example, we initiate the loading of java/lang/String in the AppClassLoader. This will allow
255 // any App classes to have a pre-resolved ConstantPool entry that references java/lang/String.
256 //
257 // TODO: we can limit the number of initiated classes to only those that are actually referenced by
258 // AOT-linked classes loaded by <initiating_loader>.
259 void AOTLinkedClassBulkLoader::initiate_loading(JavaThread* current, const char* category_name,
260 Handle initiating_loader, Array<InstanceKlass*>* classes) {
261 if (classes == nullptr) {
262 return;
263 }
264
265 assert(initiating_loader() == SystemDictionary::java_platform_loader() ||
266 initiating_loader() == SystemDictionary::java_system_loader(), "must be");
267 ClassLoaderData* loader_data = ClassLoaderData::class_loader_data(initiating_loader());
268 MonitorLocker mu1(SystemDictionary_lock);
269
270 for (int i = 0; i < classes->length(); i++) {
271 InstanceKlass* ik = classes->at(i);
272 assert(ik->is_loaded(), "must have already been loaded by a parent loader");
273 assert(ik->class_loader() != initiating_loader(), "must be a parent loader");
274 assert(ik->class_loader() == nullptr ||
275 ik->class_loader() == SystemDictionary::java_platform_loader(), "must be");
276 if (ik->is_public() && !ik->is_hidden()) {
277 if (log_is_enabled(Info, aot, load)) {
278 ResourceMark rm(current);
279 const char* defining_loader = (ik->class_loader() == nullptr ? "boot" : "plat");
280 log_info(aot, load)("%-5s %s (initiated, defined by %s)", category_name, ik->external_name(),
281 defining_loader);
282 }
283 SystemDictionary::add_to_initiating_loader(current, ik, loader_data);
284 }
285 }
286 }
287
288 // Some AOT-linked classes for <class_loader> must be initialized early. This includes
289 // - classes that were AOT-initialized by AOTClassInitializer
290 // - the classes of all objects that are reachable from the archived mirrors of
291 // the AOT-linked classes for <class_loader>.
292 void AOTLinkedClassBulkLoader::link_or_init_classes_for_loader(Handle class_loader, Array<InstanceKlass*>* classes, TRAPS) {
293 if (classes != nullptr) {
294 for (int i = 0; i < classes->length(); i++) {
295 InstanceKlass* ik = classes->at(i);
296 if (ik->class_loader_data() == nullptr) {
297 // This class is not yet loaded. We will initialize it in a later phase.
298 // For example, we have loaded only AOTLinkedClassCategory::BOOT1 classes
299 // but k is part of AOTLinkedClassCategory::BOOT2.
300 continue;
301 }
302 if (ik->has_aot_initialized_mirror()) {
303 ik->initialize_with_aot_initialized_mirror(CHECK);
304 } else {
305 // Some cached heap objects may hold references to methods in aot-linked
306 // classes (via MemberName). We need to make sure all classes are
307 // linked to allow such MemberNames to be invoked.
308 ik->link_class(CHECK);
309 }
310 }
311 }
312
313 HeapShared::init_classes_for_special_subgraph(class_loader, CHECK);
314 }
315
316 void AOTLinkedClassBulkLoader::replay_training_at_init(Array<InstanceKlass*>* classes, TRAPS) {
317 if (classes != nullptr) {
318 for (int i = 0; i < classes->length(); i++) {
319 InstanceKlass* ik = classes->at(i);
320 if (ik->has_aot_initialized_mirror() && ik->is_initialized() && !ik->has_init_deps_processed()) {
321 CompilationPolicy::replay_training_at_init(ik, CHECK);
322 }
323 }
324 }
325 }
326
327 void AOTLinkedClassBulkLoader::replay_training_at_init_for_preloaded_classes(TRAPS) {
328 if (CDSConfig::is_using_aot_linked_classes() && TrainingData::have_data()) {
329 AOTLinkedClassTable* table = AOTLinkedClassTable::get();
330 replay_training_at_init(table->boot1(), CHECK);
331 replay_training_at_init(table->boot2(), CHECK);
332 replay_training_at_init(table->platform(), CHECK);
333 replay_training_at_init(table->app(), CHECK);
334 }
335 }