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/archiveBuilder.hpp"
30 #include "cds/archiveUtils.inline.hpp"
31 #include "cds/cdsAccess.hpp"
32 #include "cds/cdsConfig.hpp"
33 #include "cds/cdsProtectionDomain.hpp"
34 #include "cds/heapShared.hpp"
35 #include "cds/lambdaFormInvokers.inline.hpp"
36 #include "classfile/classLoaderDataGraph.hpp"
37 #include "classfile/classLoaderData.hpp"
38 #include "classfile/classLoaderExt.hpp"
39 #include "classfile/classLoader.hpp"
40 #include "classfile/dictionary.hpp"
41 #include "classfile/javaClasses.hpp"
42 #include "classfile/systemDictionary.hpp"
43 #include "classfile/systemDictionaryShared.hpp"
44 #include "classfile/vmClasses.hpp"
45 #include "compiler/compilationPolicy.hpp"
46 #include "gc/shared/gcVMOperations.hpp"
47 #include "memory/resourceArea.hpp"
48 #include "oops/constantPool.inline.hpp"
49 #include "oops/instanceKlass.hpp"
50 #include "oops/klass.inline.hpp"
51 #include "oops/trainingData.hpp"
52 #include "runtime/handles.inline.hpp"
53 #include "runtime/javaCalls.hpp"
54 #include "runtime/java.hpp"
55 #include "runtime/perfData.inline.hpp"
56 #include "runtime/timer.hpp"
57 #include "services/management.hpp"
58
59 bool AOTLinkedClassBulkLoader::_boot2_completed = false;
60 bool AOTLinkedClassBulkLoader::_platform_completed = false;
61 bool AOTLinkedClassBulkLoader::_app_completed = false;
62 bool AOTLinkedClassBulkLoader::_all_completed = false;
63
64 static PerfCounter* _perf_classes_preloaded = nullptr;
65 static PerfTickCounters* _perf_class_preload_counters = nullptr;
66
67 void AOTLinkedClassBulkLoader::serialize(SerializeClosure* soc, bool is_static_archive) {
68 AOTLinkedClassTable::get(is_static_archive)->serialize(soc);
69
70 if (is_static_archive) {
71 if (soc->reading() && UsePerfData) {
72 JavaThread* THREAD = JavaThread::current();
73 NEWPERFEVENTCOUNTER(_perf_classes_preloaded, SUN_CLS, "preloadedClasses");
74 NEWPERFTICKCOUNTERS(_perf_class_preload_counters, SUN_CLS, "classPreload");
75 }
76 }
77 }
78
79 bool AOTLinkedClassBulkLoader::class_preloading_finished() {
80 if (!CDSConfig::is_using_aot_linked_classes()) {
81 return true;
82 } else {
83 // The ConstantPools of preloaded classes have references to other preloaded classes. We don't
84 // want any Java code (including JVMCI compiler) to use these classes until all of them
85 // are loaded.
86 return Atomic::load_acquire(&_all_completed);
87 }
88 }
89
90 void AOTLinkedClassBulkLoader::load_javabase_classes(JavaThread* current) {
91 assert(CDSConfig::is_using_aot_linked_classes(), "sanity");
92 load_classes_in_loader(current, AOTLinkedClassCategory::BOOT1, nullptr); // only java.base classes
93 }
94
95 void AOTLinkedClassBulkLoader::load_non_javabase_classes(JavaThread* current) {
96 assert(CDSConfig::is_using_aot_linked_classes(), "sanity");
97
98 // is_using_aot_linked_classes() requires is_using_full_module_graph(). As a result,
99 // the platform/system class loader should already have been initialized as part
100 // of the FMG support.
101 if (!CDSConfig::is_dumping_final_static_archive()) {
102 assert(CDSConfig::is_using_full_module_graph(), "must be");
103 }
104 assert(SystemDictionary::java_platform_loader() != nullptr, "must be");
105 assert(SystemDictionary::java_system_loader() != nullptr, "must be");
106
107 load_classes_in_loader(current, AOTLinkedClassCategory::BOOT2, nullptr); // all boot classes outside of java.base
108 _boot2_completed = true;
109
110 load_classes_in_loader(current, AOTLinkedClassCategory::PLATFORM, SystemDictionary::java_platform_loader());
111 _platform_completed = true;
112
113 load_classes_in_loader(current, AOTLinkedClassCategory::APP, SystemDictionary::java_system_loader());
114
115 if (PrintTrainingInfo) {
116 tty->print_cr("==================== archived_training_data ** after all classes preloaded ====================");
117 TrainingData::print_archived_training_data_on(tty);
118 }
119
120 if (log_is_enabled(Info, cds, jit)) {
121 CDSAccess::test_heap_access_api();
122 }
123
124
125 _app_completed = true;
126 Atomic::release_store(&_all_completed, true);
127 }
128
129 void AOTLinkedClassBulkLoader::load_classes_in_loader(JavaThread* current, AOTLinkedClassCategory class_category, oop class_loader_oop) {
130 load_classes_in_loader_impl(class_category, class_loader_oop, current);
131 if (current->has_pending_exception()) {
132 // We cannot continue, as we might have loaded some of the aot-linked classes, which
133 // may have dangling C++ pointers to other aot-linked classes that we have failed to load.
134 exit_on_exception(current);
135 }
136 }
137
138 void AOTLinkedClassBulkLoader::exit_on_exception(JavaThread* current) {
139 assert(current->has_pending_exception(), "precondition");
140 ResourceMark rm(current);
141 if (current->pending_exception()->is_a(vmClasses::OutOfMemoryError_klass())) {
142 log_error(cds)("Out of memory. Please run with a larger Java heap, current MaxHeapSize = "
143 "%zuM", MaxHeapSize/M);
144 } else {
145 log_error(cds)("%s: %s", current->pending_exception()->klass()->external_name(),
146 java_lang_String::as_utf8_string(java_lang_Throwable::message(current->pending_exception())));
147 }
148 vm_exit_during_initialization("Unexpected exception when loading aot-linked classes.");
149 }
150
151 void AOTLinkedClassBulkLoader::load_classes_in_loader_impl(AOTLinkedClassCategory class_category, oop class_loader_oop, TRAPS) {
152 Handle h_loader(THREAD, class_loader_oop);
153 load_table(AOTLinkedClassTable::for_static_archive(), class_category, h_loader, CHECK);
154 load_table(AOTLinkedClassTable::for_dynamic_archive(), class_category, h_loader, CHECK);
155
156 // Initialize the InstanceKlasses of all archived heap objects that are reachable from the
157 // archived java class mirrors.
158 //
159 // Only the classes in the static archive can have archived mirrors.
160 AOTLinkedClassTable* static_table = AOTLinkedClassTable::for_static_archive();
161 switch (class_category) {
162 case AOTLinkedClassCategory::BOOT1:
163 // Delayed until finish_loading_javabase_classes(), as the VM is not ready to
164 // execute some of the <clinit> methods.
165 break;
166 case AOTLinkedClassCategory::BOOT2:
167 init_required_classes_for_loader(h_loader, static_table->boot2(), CHECK);
168 break;
169 case AOTLinkedClassCategory::PLATFORM:
170 init_required_classes_for_loader(h_loader, static_table->platform(), CHECK);
171 break;
172 case AOTLinkedClassCategory::APP:
173 init_required_classes_for_loader(h_loader, static_table->app(), CHECK);
174 break;
175 case AOTLinkedClassCategory::UNREGISTERED:
176 ShouldNotReachHere();
177 break;
178 }
179
180 if (Universe::is_fully_initialized() && VerifyDuringStartup) {
181 // Make sure we're still in a clean state.
182 VM_Verify verify_op;
183 VMThread::execute(&verify_op);
184 }
185 }
186
187 void AOTLinkedClassBulkLoader::load_table(AOTLinkedClassTable* table, AOTLinkedClassCategory class_category, Handle loader, TRAPS) {
188 if (class_category != AOTLinkedClassCategory::BOOT1) {
189 assert(Universe::is_module_initialized(), "sanity");
190 }
191
192 const char* category_name = AOTClassLinker::class_category_name(class_category);
193 switch (class_category) {
194 case AOTLinkedClassCategory::BOOT1:
195 load_classes_impl(class_category, table->boot(), category_name, loader, CHECK);
196 break;
197
198 case AOTLinkedClassCategory::BOOT2:
199 load_classes_impl(class_category, table->boot2(), category_name, loader, CHECK);
200 break;
201
202 case AOTLinkedClassCategory::PLATFORM:
203 {
204 initiate_loading(THREAD, category_name, loader, table->boot());
205 initiate_loading(THREAD, category_name, loader, table->boot2());
206 load_classes_impl(class_category, table->platform(), category_name, loader, CHECK);
207 }
208 break;
209 case AOTLinkedClassCategory::APP:
210 {
211 initiate_loading(THREAD, category_name, loader, table->boot());
212 initiate_loading(THREAD, category_name, loader, table->boot2());
213 initiate_loading(THREAD, category_name, loader, table->platform());
214 load_classes_impl(class_category, table->app(), category_name, loader, CHECK);
215 }
216 break;
217 case AOTLinkedClassCategory::UNREGISTERED:
218 default:
219 ShouldNotReachHere(); // Currently aot-linked classes are not supported for this category.
220 break;
221 }
222 }
223
224 void AOTLinkedClassBulkLoader::load_classes_impl(AOTLinkedClassCategory class_category, Array<InstanceKlass*>* classes,
225 const char* category_name, Handle loader, TRAPS) {
226 if (classes == nullptr) {
227 return;
228 }
229
230 ClassLoaderData* loader_data = ClassLoaderData::class_loader_data(loader());
231
232 for (int i = 0; i < classes->length(); i++) {
233 if (UsePerfData) {
234 _perf_classes_preloaded->inc();
235 }
236 InstanceKlass* ik = classes->at(i);
237 if (log_is_enabled(Info, cds, aot, load)) {
238 ResourceMark rm(THREAD);
239 log_info(cds, aot, load)("%-5s %s%s%s", category_name, ik->external_name(),
240 ik->is_loaded() ? " (already loaded)" : "",
241 ik->is_hidden() ? " (hidden)" : "");
242 }
243
244 if (!ik->is_loaded()) {
245 if (ik->is_hidden()) {
246 load_hidden_class(loader_data, ik, CHECK);
247 } else {
248 InstanceKlass* actual;
249 if (loader_data == ClassLoaderData::the_null_class_loader_data()) {
250 actual = SystemDictionary::load_instance_class(ik->name(), loader, CHECK);
251 } else {
252 actual = SystemDictionaryShared::find_or_load_shared_class(ik->name(), loader, CHECK);
253 }
254
255 if (actual != ik) {
256 ResourceMark rm(THREAD);
257 log_error(cds)("Unable to resolve %s class from CDS archive: %s", category_name, ik->external_name());
258 log_error(cds)("Expected: " INTPTR_FORMAT ", actual: " INTPTR_FORMAT, p2i(ik), p2i(actual));
259 log_error(cds)("JVMTI class retransformation is not supported when archive was generated with -XX:+AOTClassLinking.");
260 MetaspaceShared::unrecoverable_loading_error();
261 }
262 assert(actual->is_loaded(), "must be");
263 }
264 }
265 }
266 }
267
268 // Initiate loading of the <classes> in the <initiating_loader>. The <classes> should have already been loaded
269 // by a parent loader of the <initiating_loader>. This is necessary for handling pre-resolved CP entries.
270 //
271 // For example, we initiate the loading of java/lang/String in the AppClassLoader. This will allow
272 // any App classes to have a pre-resolved ConstantPool entry that references java/lang/String.
273 //
274 // TODO: we can limit the number of initiated classes to only those that are actually referenced by
275 // AOT-linked classes loaded by <initiating_loader>.
276 void AOTLinkedClassBulkLoader::initiate_loading(JavaThread* current, const char* category_name,
277 Handle initiating_loader, Array<InstanceKlass*>* classes) {
278 if (classes == nullptr) {
279 return;
280 }
281
282 assert(initiating_loader() == SystemDictionary::java_platform_loader() ||
283 initiating_loader() == SystemDictionary::java_system_loader(), "must be");
284 ClassLoaderData* loader_data = ClassLoaderData::class_loader_data(initiating_loader());
285 MonitorLocker mu1(SystemDictionary_lock);
286
287 for (int i = 0; i < classes->length(); i++) {
288 InstanceKlass* ik = classes->at(i);
289 assert(ik->is_loaded(), "must have already been loaded by a parent loader");
290 assert(ik->class_loader() != initiating_loader(), "must be a parent loader");
291 assert(ik->class_loader() == nullptr ||
292 ik->class_loader() == SystemDictionary::java_platform_loader(), "must be");
293 if (ik->is_public() && !ik->is_hidden()) {
294 if (log_is_enabled(Info, cds, aot, load)) {
295 ResourceMark rm(current);
296 const char* defining_loader = (ik->class_loader() == nullptr ? "boot" : "plat");
297 log_info(cds, aot, load)("%s %s (initiated, defined by %s)", category_name, ik->external_name(),
298 defining_loader);
299 }
300 SystemDictionary::add_to_initiating_loader(current, ik, loader_data);
301 }
302 }
303 }
304
305 // Currently, we archive only three types of hidden classes:
306 // - LambdaForms
307 // - lambda proxy classes
308 // - StringConcat classes
309 // See HeapShared::is_archivable_hidden_klass().
310 //
311 // LambdaForm classes (with names like java/lang/invoke/LambdaForm$MH+0x800000015) logically
312 // belong to the boot loader, but they are usually stored in their own special ClassLoaderData to
313 // facilitate class unloading, as a LambdaForm may refer to a class loaded by a custom loader
314 // that may be unloaded.
315 //
316 // We only support AOT-resolution of indys in the boot/platform/app loader, so there's no need
317 // to support class unloading. For simplicity, we put all archived LambdaForm classes in the
318 // "main" ClassLoaderData of the boot loader.
319 //
320 // (Even if we were to support other loaders, we would still feel free to ignore any requirement
321 // of class unloading, for any class asset in the AOT cache. Anything that makes it into the AOT
322 // cache has a lifetime dispensation from unloading. After all, the AOT cache never grows, and
323 // we can assume that the user is content with its size, and doesn't need its footprint to shrink.)
324 //
325 // Lambda proxy classes are normally stored in the same ClassLoaderData as their nest hosts, and
326 // StringConcat are normally stored in the main ClassLoaderData of the boot class loader. We
327 // do the same for the archived copies of such classes.
328 void AOTLinkedClassBulkLoader::load_hidden_class(ClassLoaderData* loader_data, InstanceKlass* ik, TRAPS) {
329 assert(HeapShared::is_lambda_form_klass(ik) ||
330 HeapShared::is_lambda_proxy_klass(ik) ||
331 HeapShared::is_string_concat_klass(ik), "sanity");
332 DEBUG_ONLY({
333 assert(ik->java_super()->is_loaded(), "must be");
334 for (int i = 0; i < ik->local_interfaces()->length(); i++) {
335 assert(ik->local_interfaces()->at(i)->is_loaded(), "must be");
336 }
337 });
338
339 Handle pd;
340 PackageEntry* pkg_entry = nullptr;
341
342 // Since a hidden class does not have a name, it cannot be reloaded
343 // normally via the system dictionary. Instead, we have to finish the
344 // loading job here.
345
346 if (HeapShared::is_lambda_proxy_klass(ik)) {
347 InstanceKlass* nest_host = ik->nest_host_not_null();
348 assert(nest_host->is_loaded(), "must be");
349 pd = Handle(THREAD, nest_host->protection_domain());
350 pkg_entry = nest_host->package();
351 }
352
353 ik->restore_unshareable_info(loader_data, pd, pkg_entry, CHECK);
354 SystemDictionary::load_shared_class_misc(ik, loader_data);
355 ik->add_to_hierarchy(THREAD);
356 assert(ik->is_loaded(), "Must be in at least loaded state");
357
358 DEBUG_ONLY({
359 // Make sure we don't make this hidden class available by name, even if we don't
360 // use any special ClassLoaderData.
361 Handle loader(THREAD, loader_data->class_loader());
362 ResourceMark rm(THREAD);
363 assert(SystemDictionary::resolve_or_null(ik->name(), loader, THREAD) == nullptr,
364 "hidden classes cannot be accessible by name: %s", ik->external_name());
365 if (HAS_PENDING_EXCEPTION) {
366 CLEAR_PENDING_EXCEPTION;
367 }
368 });
369 }
370
371 void AOTLinkedClassBulkLoader::finish_loading_javabase_classes(TRAPS) {
372 init_required_classes_for_loader(Handle(), AOTLinkedClassTable::for_static_archive()->boot(), CHECK);
373 }
374
375 // Some AOT-linked classes for <class_loader> must be initialized early. This includes
376 // - classes that were AOT-initialized by AOTClassInitializer
377 // - the classes of all objects that are reachable from the archived mirrors of
378 // the AOT-linked classes for <class_loader>.
379 void AOTLinkedClassBulkLoader::init_required_classes_for_loader(Handle class_loader, Array<InstanceKlass*>* classes, TRAPS) {
380 if (classes != nullptr) {
381 for (int i = 0; i < classes->length(); i++) {
382 InstanceKlass* ik = classes->at(i);
383 if (ik->class_loader_data() == nullptr) {
384 // This class is not yet loaded. We will initialize it in a later phase.
385 // For example, we have loaded only AOTLinkedClassCategory::BOOT1 classes
386 // but k is part of AOTLinkedClassCategory::BOOT2.
387 continue;
388 }
389 if (ik->has_aot_initialized_mirror()) {
390 ik->initialize_with_aot_initialized_mirror(CHECK);
391 } else {
392 // Some cached heap objects may hold references to methods in aot-linked
393 // classes (via MemberName). We need to make sure all classes are
394 // linked to allow such MemberNames to be invoked.
395 if (ik->is_rewritten()) {
396 // (ik->is_rewritten() == false) means the class failed verification
397 // during the assembly phase, so there's no need to link it here.
398 ik->link_class(CHECK);
399 }
400 }
401 }
402 }
403
404 HeapShared::init_classes_for_special_subgraph(class_loader, CHECK);
405 }
406
407 bool AOTLinkedClassBulkLoader::is_pending_aot_linked_class(Klass* k) {
408 if (!CDSConfig::is_using_aot_linked_classes()) {
409 return false;
410 }
411
412 if (_all_completed) { // no more pending aot-linked classes
413 return false;
414 }
415
416 if (k->is_objArray_klass()) {
417 k = ObjArrayKlass::cast(k)->bottom_klass();
418 }
419 if (!k->is_instance_klass()) {
420 // type array klasses (and their higher dimensions),
421 // must have been loaded before a GC can ever happen.
422 return false;
423 }
424
425 // There's a small window during VM start-up where a not-yet loaded aot-linked
426 // class k may be discovered by the GC during VM initialization. This can happen
427 // when the heap contains an aot-cached instance of k, but k is not ready to be
428 // loaded yet. (TODO: JDK-8342429 eliminates this possibility)
429 //
430 // The following checks try to limit this window as much as possible for each of
431 // the four AOTLinkedClassCategory of classes that can be aot-linked.
432
433 InstanceKlass* ik = InstanceKlass::cast(k);
434 if (ik->is_shared_boot_class()) {
435 if (ik->module() != nullptr && ik->in_javabase_module()) {
436 // AOTLinkedClassCategory::BOOT1 -- all aot-linked classes in
437 // java.base must have been loaded before a GC can ever happen.
438 return false;
439 } else {
440 // AOTLinkedClassCategory::BOOT2 classes cannot be loaded until
441 // module system is ready.
442 return !_boot2_completed;
443 }
444 } else if (ik->is_shared_platform_class()) {
445 // AOTLinkedClassCategory::PLATFORM classes cannot be loaded until
446 // the platform class loader is initialized.
447 return !_platform_completed;
448 } else if (ik->is_shared_app_class()) {
449 // AOTLinkedClassCategory::APP cannot be loaded until the app class loader
450 // is initialized.
451 return !_app_completed;
452 } else {
453 return false;
454 }
455 }
456
457 void AOTLinkedClassBulkLoader::replay_training_at_init(Array<InstanceKlass*>* classes, TRAPS) {
458 if (classes != nullptr) {
459 for (int i = 0; i < classes->length(); i++) {
460 InstanceKlass* ik = classes->at(i);
461 if (ik->has_aot_initialized_mirror() && ik->is_initialized() && !ik->has_init_deps_processed()) {
462 CompilationPolicy::replay_training_at_init(ik, CHECK);
463 }
464 }
465 }
466 }
467
468 void AOTLinkedClassBulkLoader::replay_training_at_init_for_preloaded_classes(TRAPS) {
469 if (CDSConfig::is_using_aot_linked_classes() && TrainingData::have_data()) {
470 // Only static archive can have training data.
471 AOTLinkedClassTable* table = AOTLinkedClassTable::for_static_archive();
472 replay_training_at_init(table->boot(), CHECK);
473 replay_training_at_init(table->boot2(), CHECK);
474 replay_training_at_init(table->platform(), CHECK);
475 replay_training_at_init(table->app(), CHECK);
476 }
477 }
478
479 void AOTLinkedClassBulkLoader::print_counters_on(outputStream* st) {
480 if (UsePerfData && _perf_class_preload_counters != nullptr) {
481 st->print_cr("AOTLinkedClassBulkLoader:");
482 st->print_cr(" preload: " JLONG_FORMAT_W(6) "us (elapsed) " JLONG_FORMAT_W(6) " (thread) / " JLONG_FORMAT_W(5) " events",
483 _perf_class_preload_counters->elapsed_counter_value_us(),
484 _perf_class_preload_counters->thread_counter_value_us(),
485 _perf_classes_preloaded->get_value());
486 }
487 }