1 /*
2 * Copyright (c) 2024, 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 "precompiled.hpp"
26 #include "cds/aotClassInitializer.hpp"
27 #include "cds/aotClassLinker.hpp"
28 #include "cds/aotLinkedClassBulkLoader.hpp"
29 #include "cds/aotLinkedClassTable.hpp"
30 #include "cds/cdsConfig.hpp"
31 #include "cds/heapShared.hpp"
32 #include "classfile/classLoaderData.hpp"
33 #include "classfile/systemDictionary.hpp"
34 #include "classfile/systemDictionaryShared.hpp"
35 #include "classfile/vmClasses.hpp"
36 #include "gc/shared/gcVMOperations.hpp"
37 #include "memory/resourceArea.hpp"
38 #include "oops/instanceKlass.hpp"
39 #include "oops/klass.inline.hpp"
40 #include "runtime/handles.inline.hpp"
41 #include "runtime/java.hpp"
42
43 bool AOTLinkedClassBulkLoader::_boot2_completed = false;
44 bool AOTLinkedClassBulkLoader::_platform_completed = false;
45 bool AOTLinkedClassBulkLoader::_app_completed = false;
46 bool AOTLinkedClassBulkLoader::_all_completed = false;
47
48 void AOTLinkedClassBulkLoader::serialize(SerializeClosure* soc, bool is_static_archive) {
49 AOTLinkedClassTable::get(is_static_archive)->serialize(soc);
50 }
51
52 void AOTLinkedClassBulkLoader::load_javabase_classes(JavaThread* current) {
53 assert(CDSConfig::is_using_aot_linked_classes(), "sanity");
54 load_classes_in_loader(current, AOTLinkedClassCategory::BOOT1, nullptr); // only java.base classes
55 }
56
57 void AOTLinkedClassBulkLoader::load_non_javabase_classes(JavaThread* current) {
58 assert(CDSConfig::is_using_aot_linked_classes(), "sanity");
59
60 // is_using_aot_linked_classes() requires is_using_full_module_graph(). As a result,
61 // the platform/system class loader should already have been initialized as part
62 // of the FMG support.
63 assert(CDSConfig::is_using_full_module_graph(), "must be");
64 assert(SystemDictionary::java_platform_loader() != nullptr, "must be");
65 assert(SystemDictionary::java_system_loader() != nullptr, "must be");
66
67 load_classes_in_loader(current, AOTLinkedClassCategory::BOOT2, nullptr); // all boot classes outside of java.base
68 _boot2_completed = true;
69
70 load_classes_in_loader(current, AOTLinkedClassCategory::PLATFORM, SystemDictionary::java_platform_loader());
71 _platform_completed = true;
72
73 load_classes_in_loader(current, AOTLinkedClassCategory::APP, SystemDictionary::java_system_loader());
74 _app_completed = true;
75 _all_completed = true;
76 }
77
78 void AOTLinkedClassBulkLoader::load_classes_in_loader(JavaThread* current, AOTLinkedClassCategory class_category, oop class_loader_oop) {
79 load_classes_in_loader_impl(class_category, class_loader_oop, current);
80 if (current->has_pending_exception()) {
81 // We cannot continue, as we might have loaded some of the aot-linked classes, which
82 // may have dangling C++ pointers to other aot-linked classes that we have failed to load.
83 exit_on_exception(current);
84 }
85 }
86
87 void AOTLinkedClassBulkLoader::exit_on_exception(JavaThread* current) {
88 assert(current->has_pending_exception(), "precondition");
89 ResourceMark rm(current);
90 if (current->pending_exception()->is_a(vmClasses::OutOfMemoryError_klass())) {
91 log_error(cds)("Out of memory. Please run with a larger Java heap, current MaxHeapSize = "
92 SIZE_FORMAT "M", MaxHeapSize/M);
93 } else {
94 log_error(cds)("%s: %s", current->pending_exception()->klass()->external_name(),
95 java_lang_String::as_utf8_string(java_lang_Throwable::message(current->pending_exception())));
96 }
97 vm_exit_during_initialization("Unexpected exception when loading aot-linked classes.");
98 }
99
100 void AOTLinkedClassBulkLoader::load_classes_in_loader_impl(AOTLinkedClassCategory class_category, oop class_loader_oop, TRAPS) {
101 Handle h_loader(THREAD, class_loader_oop);
102 load_table(AOTLinkedClassTable::for_static_archive(), class_category, h_loader, CHECK);
103 load_table(AOTLinkedClassTable::for_dynamic_archive(), class_category, h_loader, CHECK);
104
105 // Initialize the InstanceKlasses of all archived heap objects that are reachable from the
106 // archived java class mirrors.
107 //
108 // Only the classes in the static archive can have archived mirrors.
109 AOTLinkedClassTable* static_table = AOTLinkedClassTable::for_static_archive();
110 switch (class_category) {
111 case AOTLinkedClassCategory::BOOT1:
112 // Delayed until finish_loading_javabase_classes(), as the VM is not ready to
113 // execute some of the <clinit> methods.
114 break;
115 case AOTLinkedClassCategory::BOOT2:
116 init_required_classes_for_loader(h_loader, static_table->boot2(), CHECK);
117 break;
118 case AOTLinkedClassCategory::PLATFORM:
119 init_required_classes_for_loader(h_loader, static_table->platform(), CHECK);
120 break;
121 case AOTLinkedClassCategory::APP:
122 init_required_classes_for_loader(h_loader, static_table->app(), CHECK);
123 break;
124 case AOTLinkedClassCategory::UNREGISTERED:
125 ShouldNotReachHere();
126 break;
127 }
128
129 if (Universe::is_fully_initialized() && VerifyDuringStartup) {
130 // Make sure we're still in a clean state.
131 VM_Verify verify_op;
132 VMThread::execute(&verify_op);
133 }
134 }
135
136 void AOTLinkedClassBulkLoader::load_table(AOTLinkedClassTable* table, AOTLinkedClassCategory class_category, Handle loader, TRAPS) {
137 if (class_category != AOTLinkedClassCategory::BOOT1) {
138 assert(Universe::is_module_initialized(), "sanity");
139 }
140
141 const char* category_name = AOTClassLinker::class_category_name(class_category);
142 switch (class_category) {
143 case AOTLinkedClassCategory::BOOT1:
144 load_classes_impl(class_category, table->boot(), category_name, loader, CHECK);
145 break;
146
147 case AOTLinkedClassCategory::BOOT2:
148 load_classes_impl(class_category, table->boot2(), category_name, loader, CHECK);
149 break;
150
151 case AOTLinkedClassCategory::PLATFORM:
152 {
153 initiate_loading(THREAD, category_name, loader, table->boot());
154 initiate_loading(THREAD, category_name, loader, table->boot2());
155 load_classes_impl(class_category, table->platform(), category_name, loader, CHECK);
156 }
157 break;
158 case AOTLinkedClassCategory::APP:
159 {
160 initiate_loading(THREAD, category_name, loader, table->boot());
161 initiate_loading(THREAD, category_name, loader, table->boot2());
162 initiate_loading(THREAD, category_name, loader, table->platform());
163 load_classes_impl(class_category, table->app(), category_name, loader, CHECK);
164 }
165 break;
166 case AOTLinkedClassCategory::UNREGISTERED:
167 default:
168 ShouldNotReachHere(); // Currently aot-linked classes are not supported for this category.
169 break;
170 }
171 }
172
173 void AOTLinkedClassBulkLoader::load_classes_impl(AOTLinkedClassCategory class_category, Array<InstanceKlass*>* classes,
174 const char* category_name, Handle loader, TRAPS) {
175 if (classes == nullptr) {
176 return;
177 }
178
179 ClassLoaderData* loader_data = ClassLoaderData::class_loader_data(loader());
180
181 for (int i = 0; i < classes->length(); i++) {
182 InstanceKlass* ik = classes->at(i);
183 if (log_is_enabled(Info, cds, aot, load)) {
184 ResourceMark rm(THREAD);
185 log_info(cds, aot, load)("%-5s %s%s%s", category_name, ik->external_name(),
186 ik->is_loaded() ? " (already loaded)" : "",
187 ik->is_hidden() ? " (hidden)" : "");
188 }
189
190 if (!ik->is_loaded()) {
191 if (ik->is_hidden()) {
192 load_hidden_class(loader_data, ik, CHECK);
193 } else {
194 InstanceKlass* actual;
195 if (loader_data == ClassLoaderData::the_null_class_loader_data()) {
196 actual = SystemDictionary::load_instance_class(ik->name(), loader, CHECK);
197 } else {
198 actual = SystemDictionaryShared::find_or_load_shared_class(ik->name(), loader, CHECK);
199 }
200
201 if (actual != ik) {
202 ResourceMark rm(THREAD);
203 log_error(cds)("Unable to resolve %s class from CDS archive: %s", category_name, ik->external_name());
204 log_error(cds)("Expected: " INTPTR_FORMAT ", actual: " INTPTR_FORMAT, p2i(ik), p2i(actual));
205 log_error(cds)("JVMTI class retransformation is not supported when archive was generated with -XX:+AOTClassLinking.");
206 MetaspaceShared::unrecoverable_loading_error();
207 }
208 assert(actual->is_loaded(), "must be");
209 }
210 }
211 }
212 }
213
214 // Initiate loading of the <classes> in the <initiating_loader>. The <classes> should have already been loaded
215 // by a parent loader of the <initiating_loader>. This is necessary for handling pre-resolved CP entries.
216 //
217 // For example, we initiate the loading of java/lang/String in the AppClassLoader. This will allow
218 // any App classes to have a pre-resolved ConstantPool entry that references java/lang/String.
219 //
220 // TODO: we can limit the number of initiated classes to only those that are actually referenced by
221 // AOT-linked classes loaded by <initiating_loader>.
222 void AOTLinkedClassBulkLoader::initiate_loading(JavaThread* current, const char* category_name,
223 Handle initiating_loader, Array<InstanceKlass*>* classes) {
224 if (classes == nullptr) {
225 return;
226 }
227
228 assert(initiating_loader() == SystemDictionary::java_platform_loader() ||
229 initiating_loader() == SystemDictionary::java_system_loader(), "must be");
230 ClassLoaderData* loader_data = ClassLoaderData::class_loader_data(initiating_loader());
231 MonitorLocker mu1(SystemDictionary_lock);
232
233 for (int i = 0; i < classes->length(); i++) {
234 InstanceKlass* ik = classes->at(i);
235 assert(ik->is_loaded(), "must have already been loaded by a parent loader");
236 assert(ik->class_loader() != initiating_loader(), "must be a parent loader");
237 assert(ik->class_loader() == nullptr ||
238 ik->class_loader() == SystemDictionary::java_platform_loader(), "must be");
239 if (ik->is_public() && !ik->is_hidden()) {
240 if (log_is_enabled(Info, cds, aot, load)) {
241 ResourceMark rm(current);
242 const char* defining_loader = (ik->class_loader() == nullptr ? "boot" : "plat");
243 log_info(cds, aot, load)("%s %s (initiated, defined by %s)", category_name, ik->external_name(),
244 defining_loader);
245 }
246 SystemDictionary::add_to_initiating_loader(current, ik, loader_data);
247 }
248 }
249 }
250
251 // Currently, we archive only three types of hidden classes:
252 // - LambdaForms
253 // - lambda proxy classes
254 // - StringConcat classes
255 // See HeapShared::is_archivable_hidden_klass().
256 //
257 // LambdaForm classes (with names like java/lang/invoke/LambdaForm$MH+0x800000015) logically
258 // belong to the boot loader, but they are usually stored in their own special ClassLoaderData to
259 // facilitate class unloading, as a LambdaForm may refer to a class loaded by a custom loader
260 // that may be unloaded.
261 //
262 // We only support AOT-resolution of indys in the boot/platform/app loader, so there's no need
263 // to support class unloading. For simplicity, we put all archived LambdaForm classes in the
264 // "main" ClassLoaderData of the boot loader.
265 //
266 // (Even if we were to support other loaders, we would still feel free to ignore any requirement
267 // of class unloading, for any class asset in the AOT cache. Anything that makes it into the AOT
268 // cache has a lifetime dispensation from unloading. After all, the AOT cache never grows, and
269 // we can assume that the user is content with its size, and doesn't need its footprint to shrink.)
270 //
271 // Lambda proxy classes are normally stored in the same ClassLoaderData as their nest hosts, and
272 // StringConcat are normally stored in the main ClassLoaderData of the boot class loader. We
273 // do the same for the archived copies of such classes.
274 void AOTLinkedClassBulkLoader::load_hidden_class(ClassLoaderData* loader_data, InstanceKlass* ik, TRAPS) {
275 assert(HeapShared::is_lambda_form_klass(ik) ||
276 HeapShared::is_lambda_proxy_klass(ik) ||
277 HeapShared::is_string_concat_klass(ik), "sanity");
278 DEBUG_ONLY({
279 assert(ik->java_super()->is_loaded(), "must be");
280 for (int i = 0; i < ik->local_interfaces()->length(); i++) {
281 assert(ik->local_interfaces()->at(i)->is_loaded(), "must be");
282 }
283 });
284
285 Handle pd;
286 PackageEntry* pkg_entry = nullptr;
287
288 // Since a hidden class does not have a name, it cannot be reloaded
289 // normally via the system dictionary. Instead, we have to finish the
290 // loading job here.
291
292 if (HeapShared::is_lambda_proxy_klass(ik)) {
293 InstanceKlass* nest_host = ik->nest_host_not_null();
294 assert(nest_host->is_loaded(), "must be");
295 pd = Handle(THREAD, nest_host->protection_domain());
296 pkg_entry = nest_host->package();
297 }
298
299 ik->restore_unshareable_info(loader_data, pd, pkg_entry, CHECK);
300 SystemDictionary::load_shared_class_misc(ik, loader_data);
301 ik->add_to_hierarchy(THREAD);
302 assert(ik->is_loaded(), "Must be in at least loaded state");
303
304 DEBUG_ONLY({
305 // Make sure we don't make this hidden class available by name, even if we don't
306 // use any special ClassLoaderData.
307 Handle loader(THREAD, loader_data->class_loader());
308 ResourceMark rm(THREAD);
309 assert(SystemDictionary::resolve_or_null(ik->name(), loader, pd, THREAD) == nullptr,
310 "hidden classes cannot be accessible by name: %s", ik->external_name());
311 if (HAS_PENDING_EXCEPTION) {
312 CLEAR_PENDING_EXCEPTION;
313 }
314 });
315 }
316
317 void AOTLinkedClassBulkLoader::finish_loading_javabase_classes(TRAPS) {
318 init_required_classes_for_loader(Handle(), AOTLinkedClassTable::for_static_archive()->boot(), CHECK);
319 }
320
321 // Some AOT-linked classes for <class_loader> must be initialized early. This includes
322 // - classes that were AOT-initialized by AOTClassInitializer
323 // - the classes of all objects that are reachable from the archived mirrors of
324 // the AOT-linked classes for <class_loader>.
325 void AOTLinkedClassBulkLoader::init_required_classes_for_loader(Handle class_loader, Array<InstanceKlass*>* classes, TRAPS) {
326 if (classes != nullptr) {
327 for (int i = 0; i < classes->length(); i++) {
328 InstanceKlass* ik = classes->at(i);
329 if (ik->class_loader_data() == nullptr) {
330 // This class is not yet loaded. We will initialize it in a later phase.
331 // For example, we have loaded only AOTLinkedClassCategory::BOOT1 classes
332 // but k is part of AOTLinkedClassCategory::BOOT2.
333 continue;
334 }
335 if (ik->has_aot_initialized_mirror()) {
336 ik->initialize_with_aot_initialized_mirror(CHECK);
337 } else {
338 // Some cached heap objects may hold references to methods in aot-linked
339 // classes (via MemberName). We need to make sure all classes are
340 // linked to allow such MemberNames to be invoked.
341 ik->link_class(CHECK);
342 }
343 }
344 }
345
346 HeapShared::init_classes_for_special_subgraph(class_loader, CHECK);
347 }
348
349 bool AOTLinkedClassBulkLoader::is_pending_aot_linked_class(Klass* k) {
350 if (!CDSConfig::is_using_aot_linked_classes()) {
351 return false;
352 }
353
354 if (_all_completed) { // no more pending aot-linked classes
355 return false;
356 }
357
358 if (k->is_objArray_klass()) {
359 k = ObjArrayKlass::cast(k)->bottom_klass();
360 }
361 if (!k->is_instance_klass()) {
362 // type array klasses (and their higher dimensions),
363 // must have been loaded before a GC can ever happen.
364 return false;
365 }
366
367 // There's a small window during VM start-up where a not-yet loaded aot-linked
368 // class k may be discovered by the GC during VM initialization. This can happen
369 // when the heap contains an aot-cached instance of k, but k is not ready to be
370 // loaded yet. (TODO: JDK-8342429 eliminates this possibility)
371 //
372 // The following checks try to limit this window as much as possible for each of
373 // the four AOTLinkedClassCategory of classes that can be aot-linked.
374
375 InstanceKlass* ik = InstanceKlass::cast(k);
376 if (ik->is_shared_boot_class()) {
377 if (ik->module() != nullptr && ik->in_javabase_module()) {
378 // AOTLinkedClassCategory::BOOT1 -- all aot-linked classes in
379 // java.base must have been loaded before a GC can ever happen.
380 return false;
381 } else {
382 // AOTLinkedClassCategory::BOOT2 classes cannot be loaded until
383 // module system is ready.
384 return !_boot2_completed;
385 }
386 } else if (ik->is_shared_platform_class()) {
387 // AOTLinkedClassCategory::PLATFORM classes cannot be loaded until
388 // the platform class loader is initialized.
389 return !_platform_completed;
390 } else if (ik->is_shared_app_class()) {
391 // AOTLinkedClassCategory::APP cannot be loaded until the app class loader
392 // is initialized.
393 return !_app_completed;
394 } else {
395 return false;
396 }
397 }