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