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