1 /*
2 * Copyright (c) 1997, 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 *
38 #include "classfile/packageEntry.hpp"
39 #include "classfile/placeholders.hpp"
40 #include "classfile/resolutionErrors.hpp"
41 #include "classfile/stringTable.hpp"
42 #include "classfile/symbolTable.hpp"
43 #include "classfile/systemDictionary.hpp"
44 #include "classfile/vmClasses.hpp"
45 #include "classfile/vmSymbols.hpp"
46 #include "gc/shared/gcTraceTime.inline.hpp"
47 #include "interpreter/bootstrapInfo.hpp"
48 #include "jfr/jfrEvents.hpp"
49 #include "jvm.h"
50 #include "logging/log.hpp"
51 #include "logging/logStream.hpp"
52 #include "memory/metaspaceClosure.hpp"
53 #include "memory/oopFactory.hpp"
54 #include "memory/resourceArea.hpp"
55 #include "memory/universe.hpp"
56 #include "oops/access.inline.hpp"
57 #include "oops/constantPool.inline.hpp"
58 #include "oops/instanceKlass.hpp"
59 #include "oops/klass.inline.hpp"
60 #include "oops/method.inline.hpp"
61 #include "oops/objArrayKlass.hpp"
62 #include "oops/objArrayOop.inline.hpp"
63 #include "oops/oop.inline.hpp"
64 #include "oops/oopHandle.inline.hpp"
65 #include "oops/symbol.hpp"
66 #include "oops/typeArrayKlass.hpp"
67 #include "prims/jvmtiExport.hpp"
68 #include "prims/methodHandles.hpp"
69 #include "runtime/arguments.hpp"
70 #include "runtime/atomicAccess.hpp"
71 #include "runtime/handles.inline.hpp"
72 #include "runtime/java.hpp"
73 #include "runtime/javaCalls.hpp"
74 #include "runtime/mutexLocker.hpp"
75 #include "runtime/sharedRuntime.hpp"
76 #include "runtime/signature.hpp"
77 #include "runtime/synchronizer.hpp"
78 #include "services/classLoadingService.hpp"
79 #include "services/diagnosticCommand.hpp"
80 #include "services/finalizerService.hpp"
81 #include "services/threadService.hpp"
82 #include "utilities/growableArray.hpp"
83 #include "utilities/macros.hpp"
84 #include "utilities/utf8.hpp"
85 #if INCLUDE_CDS
86 #include "classfile/systemDictionaryShared.hpp"
87 #endif
88 #if INCLUDE_JFR
89 #include "jfr/jfr.hpp"
90 #endif
91
92 class InvokeMethodKey : public StackObj {
93 private:
94 Symbol* _symbol;
169 CHECK_NULL);
170 return result.get_oop();
171 }
172
173 oop SystemDictionary::get_platform_class_loader_impl(TRAPS) {
174 JavaValue result(T_OBJECT);
175 InstanceKlass* class_loader_klass = vmClasses::ClassLoader_klass();
176 JavaCalls::call_static(&result,
177 class_loader_klass,
178 vmSymbols::getPlatformClassLoader_name(),
179 vmSymbols::void_classloader_signature(),
180 CHECK_NULL);
181 return result.get_oop();
182 }
183
184 // Helper function
185 inline ClassLoaderData* class_loader_data(Handle class_loader) {
186 return ClassLoaderData::class_loader_data(class_loader());
187 }
188
189 ClassLoaderData* SystemDictionary::register_loader(Handle class_loader, bool create_mirror_cld) {
190 if (create_mirror_cld) {
191 // Add a new class loader data to the graph.
192 return ClassLoaderDataGraph::add(class_loader, true);
193 } else {
194 return (class_loader() == nullptr) ? ClassLoaderData::the_null_class_loader_data() :
195 ClassLoaderDataGraph::find_or_create(class_loader);
196 }
197 }
198
199 void SystemDictionary::set_system_loader(ClassLoaderData *cld) {
200 if (_java_system_loader.is_empty()) {
201 _java_system_loader = cld->class_loader_handle();
202 } else {
203 assert(_java_system_loader.resolve() == cld->class_loader(), "sanity");
204 }
205 }
206
207 void SystemDictionary::set_platform_loader(ClassLoaderData *cld) {
208 if (_java_platform_loader.is_empty()) {
209 _java_platform_loader = cld->class_loader_handle();
210 } else {
211 assert(_java_platform_loader.resolve() == cld->class_loader(), "sanity");
212 }
213 }
214
215 // ----------------------------------------------------------------------------
383 }
384 } else {
385 k = Universe::typeArrayKlass(t);
386 k = k->array_klass(ndims, CHECK_NULL);
387 }
388 return k;
389 }
390
391 static inline void log_circularity_error(Symbol* name, PlaceholderEntry* probe) {
392 LogTarget(Debug, class, load, placeholders) lt;
393 if (lt.is_enabled()) {
394 ResourceMark rm;
395 LogStream ls(lt);
396 ls.print("ClassCircularityError detected for placeholder entry %s", name->as_C_string());
397 probe->print_on(&ls);
398 ls.cr();
399 }
400 }
401
402 // Must be called for any superclass or superinterface resolution
403 // during class definition to allow class circularity checking
404 // superinterface callers:
405 // parse_interfaces - from defineClass
406 // superclass callers:
407 // ClassFileParser - from defineClass
408 // load_shared_class - while loading a class from shared archive
409 // resolve_instance_class_or_null:
410 // via: handle_parallel_super_load
411 // when resolving a class that has an existing placeholder with
412 // a saved superclass [i.e. a defineClass is currently in progress]
413 // If another thread is trying to resolve the class, it must do
414 // superclass checks on its own thread to catch class circularity and
415 // to avoid deadlock.
416 //
417 // resolve_with_circularity_detection adds a DETECT_CIRCULARITY placeholder to the placeholder table before calling
418 // resolve_instance_class_or_null. ClassCircularityError is detected when a DETECT_CIRCULARITY or LOAD_INSTANCE
419 // placeholder for the same thread, class, classloader is found.
420 // This can be seen with logging option: -Xlog:class+load+placeholders=debug.
421 //
422 InstanceKlass* SystemDictionary::resolve_with_circularity_detection(Symbol* class_name,
423 Symbol* next_name,
424 Handle class_loader,
425 bool is_superclass,
426 TRAPS) {
427
428 assert(next_name != nullptr, "null superclass for resolving");
429 assert(!Signature::is_array(next_name), "invalid superclass name");
430
431 ClassLoaderData* loader_data = class_loader_data(class_loader);
432
433 if (is_superclass) {
434 InstanceKlass* klassk = loader_data->dictionary()->find_class(THREAD, class_name);
435 if (klassk != nullptr) {
436 // We can come here for two reasons:
437 // (a) RedefineClasses -- the class is already loaded
438 // (b) Rarely, the class might have been loaded by a parallel thread
439 // We can do a quick check against the already assigned superclass's name and loader.
440 InstanceKlass* superk = klassk->super();
441 if (superk != nullptr &&
442 superk->name() == next_name &&
443 superk->class_loader() == class_loader()) {
444 return superk;
445 }
446 }
447 }
448
449 // can't throw error holding a lock
450 bool throw_circularity_error = false;
451 {
452 MutexLocker mu(THREAD, SystemDictionary_lock);
453
454 // Must check ClassCircularity before resolving next_name (superclass or interface).
455 PlaceholderEntry* probe = PlaceholderTable::get_entry(class_name, loader_data);
456 if (probe != nullptr && probe->check_seen_thread(THREAD, PlaceholderTable::DETECT_CIRCULARITY)) {
457 log_circularity_error(class_name, probe);
458 throw_circularity_error = true;
459 }
460
461 // Make sure there's a placeholder for the class_name before resolving.
462 // This is used as a claim that this thread is currently loading superclass/classloader
463 // and for ClassCircularity checks.
464 if (!throw_circularity_error) {
465 // Be careful not to exit resolve_with_circularity_detection without removing this placeholder.
466 PlaceholderEntry* newprobe = PlaceholderTable::find_and_add(class_name,
467 loader_data,
468 PlaceholderTable::DETECT_CIRCULARITY,
469 next_name, THREAD);
470 }
471 }
472
473 if (throw_circularity_error) {
474 ResourceMark rm(THREAD);
475 THROW_MSG_NULL(vmSymbols::java_lang_ClassCircularityError(), class_name->as_C_string());
476 }
477
478 // Resolve the superclass or superinterface, check results on return
479 InstanceKlass* superk =
480 SystemDictionary::resolve_instance_class_or_null(next_name,
481 class_loader,
482 THREAD);
483
484 // Clean up placeholder entry.
485 {
486 MutexLocker mu(THREAD, SystemDictionary_lock);
487 PlaceholderTable::find_and_remove(class_name, loader_data, PlaceholderTable::DETECT_CIRCULARITY, THREAD);
488 SystemDictionary_lock->notify_all();
489 }
490
491 // Check for pending exception or null superk, and throw exception
492 if (HAS_PENDING_EXCEPTION || superk == nullptr) {
493 handle_resolution_exception(next_name, true, CHECK_NULL);
494 }
495
496 return superk;
497 }
498
896
897 InstanceKlass* SystemDictionary::resolve_from_stream(ClassFileStream* st,
898 Symbol* class_name,
899 Handle class_loader,
900 const ClassLoadInfo& cl_info,
901 TRAPS) {
902 if (cl_info.is_hidden()) {
903 return resolve_hidden_class_from_stream(st, class_name, class_loader, cl_info, CHECK_NULL);
904 } else {
905 return resolve_class_from_stream(st, class_name, class_loader, cl_info, CHECK_NULL);
906 }
907 }
908
909
910 #if INCLUDE_CDS
911 // Check if a shared class can be loaded by the specific classloader.
912 bool SystemDictionary::is_shared_class_visible(Symbol* class_name,
913 InstanceKlass* ik,
914 PackageEntry* pkg_entry,
915 Handle class_loader) {
916 assert(!ModuleEntryTable::javabase_moduleEntry()->is_patched(),
917 "Cannot use sharing if java.base is patched");
918
919 // (1) Check if we are loading into the same loader as in dump time.
920
921 if (ik->defined_by_boot_loader()) {
922 if (class_loader() != nullptr) {
923 return false;
924 }
925 } else if (ik->defined_by_platform_loader()) {
926 if (class_loader() != java_platform_loader()) {
927 return false;
928 }
929 } else if (ik->defined_by_app_loader()) {
930 if (class_loader() != java_system_loader()) {
931 return false;
932 }
933 } else {
934 // ik was loaded by a custom loader during dump time
935 if (class_loader_data(class_loader)->is_builtin_class_loader_data()) {
1051 class_loader, true,
1052 CHECK_false);
1053 if (!check_super) {
1054 return false;
1055 }
1056 }
1057
1058 Array<InstanceKlass*>* interfaces = ik->local_interfaces();
1059 int num_interfaces = interfaces->length();
1060 for (int index = 0; index < num_interfaces; index++) {
1061 bool check_interface = check_shared_class_super_type(ik, interfaces->at(index), class_loader, false,
1062 CHECK_false);
1063 if (!check_interface) {
1064 return false;
1065 }
1066 }
1067
1068 return true;
1069 }
1070
1071 InstanceKlass* SystemDictionary::load_shared_class(InstanceKlass* ik,
1072 Handle class_loader,
1073 Handle protection_domain,
1074 const ClassFileStream *cfs,
1075 PackageEntry* pkg_entry,
1076 TRAPS) {
1077 assert(ik != nullptr, "sanity");
1078 assert(ik->in_aot_cache(), "sanity");
1079 assert(!ik->is_unshareable_info_restored(), "shared class can be restored only once");
1080 assert(AtomicAccess::add(&ik->_shared_class_load_count, 1) == 1, "shared class loaded more than once");
1081 Symbol* class_name = ik->name();
1082
1083 if (!is_shared_class_visible(class_name, ik, pkg_entry, class_loader)) {
1084 ik->set_shared_loading_failed();
1085 return nullptr;
1086 }
1087
1088 bool check = check_shared_class_super_types(ik, class_loader, CHECK_NULL);
1089 if (!check) {
1090 ik->set_shared_loading_failed();
1091 return nullptr;
1092 }
1093
1094 InstanceKlass* new_ik = nullptr;
1095 // CFLH check is skipped for VM hidden classes (see KlassFactory::create_from_stream).
1096 // It will be skipped for shared VM hidden lambda proxy classes.
1097 if (!ik->is_hidden()) {
1098 new_ik = KlassFactory::check_shared_class_file_load_hook(
1099 ik, class_name, class_loader, protection_domain, cfs, CHECK_NULL);
1100 }
1101 if (new_ik != nullptr) {
1102 // The class is changed by CFLH. Return the new class. The shared class is
1103 // not used.
1104 return new_ik;
1105 }
1106
1107 // Adjust methods to recover missing data. They need addresses for
1108 // interpreter entry points and their default native method address
1109 // must be reset.
1110
1111 // Shared classes are all currently loaded by either the bootstrap or
1112 // internal parallel class loaders, so this will never cause a deadlock
1113 // on a custom class loader lock.
1114 // Since this class is already locked with parallel capable class
1115 // loaders, including the bootstrap loader via the placeholder table,
1116 // this lock is currently a nop.
1117
1118 ClassLoaderData* loader_data = class_loader_data(class_loader);
1119 {
1120 HandleMark hm(THREAD);
1121 Handle lockObject = get_loader_lock_or_null(class_loader);
1122 ObjectLocker ol(lockObject, THREAD);
1123 // prohibited package check assumes all classes loaded from archive call
1124 // restore_unshareable_info which calls ik->set_package()
1125 ik->restore_unshareable_info(loader_data, protection_domain, pkg_entry, CHECK_NULL);
1126 }
1127
1128 load_shared_class_misc(ik, loader_data);
1129 return ik;
1130 }
1131
1132 void SystemDictionary::load_shared_class_misc(InstanceKlass* ik, ClassLoaderData* loader_data) {
1133 ik->print_class_load_logging(loader_data, nullptr, nullptr);
1134
1135 // For boot loader, ensure that GetSystemPackage knows that a class in this
1136 // package was loaded.
1137 if (loader_data->is_the_null_class_loader_data()) {
1138 s2 path_index = ik->shared_classpath_index();
1139 ik->set_classpath_index(path_index);
1140 }
1141
1142 // notify a class loaded from shared object
1143 ClassLoadingService::notify_class_loaded(ik, true /* shared class */);
1144
1145 if (CDSConfig::is_dumping_final_static_archive()) {
1146 SystemDictionaryShared::init_dumptime_info_from_preimage(ik);
1147 }
1148 }
1690 }
1691 }
1692
1693 // Update class loader data dictionary - done after check_constraint and add_to_hierarchy
1694 // have been called.
1695 void SystemDictionary::update_dictionary(JavaThread* current,
1696 InstanceKlass* k,
1697 ClassLoaderData* loader_data) {
1698 MonitorLocker mu1(SystemDictionary_lock);
1699
1700 // Make a new dictionary entry.
1701 Symbol* name = k->name();
1702 Dictionary* dictionary = loader_data->dictionary();
1703 InstanceKlass* sd_check = dictionary->find_class(current, name);
1704 if (sd_check == nullptr) {
1705 dictionary->add_klass(current, name, k);
1706 }
1707 mu1.notify_all();
1708 }
1709
1710 #if INCLUDE_CDS
1711 // Indicate that loader_data has initiated the loading of class k, which
1712 // has already been defined by a parent loader.
1713 // This API should be used only by AOTLinkedClassBulkLoader
1714 void SystemDictionary::add_to_initiating_loader(JavaThread* current,
1715 InstanceKlass* k,
1716 ClassLoaderData* loader_data) {
1717 assert(CDSConfig::is_using_aot_linked_classes(), "must be");
1718 assert_locked_or_safepoint(SystemDictionary_lock);
1719 Symbol* name = k->name();
1720 Dictionary* dictionary = loader_data->dictionary();
1721 assert(k->is_loaded(), "must be");
1722 assert(k->class_loader_data() != loader_data, "only for classes defined by a parent loader");
1723 assert(dictionary->find_class(current, name) == nullptr, "sanity");
1724 dictionary->add_klass(current, name, k);
1725 }
1726 #endif
1727
1728 // Try to find a class name using the loader constraints. The
1729 // loader constraints might know about a class that isn't fully loaded
1730 // yet and these will be ignored.
1731 Klass* SystemDictionary::find_constrained_instance_or_array_klass(
1732 Thread* current, Symbol* class_name, Handle class_loader) {
1733
1734 // First see if it has been loaded directly.
1735 Klass* klass = find_instance_or_array_klass(current, class_name, class_loader);
1736 if (klass != nullptr)
1737 return klass;
1738
1739 // Now look to see if it has been loaded elsewhere, and is subject to
1740 // a loader constraint that would require this loader to return the
1741 // klass that is already loaded.
1742 if (Signature::is_array(class_name)) {
1743 // For array classes, their Klass*s are not kept in the
1744 // constraint table. The element Klass*s are.
1745 SignatureStream ss(class_name, false);
1746 int ndims = ss.skip_array_prefix(); // skip all '['s
|
1 /*
2 * Copyright (c) 1997, 2026, 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 *
38 #include "classfile/packageEntry.hpp"
39 #include "classfile/placeholders.hpp"
40 #include "classfile/resolutionErrors.hpp"
41 #include "classfile/stringTable.hpp"
42 #include "classfile/symbolTable.hpp"
43 #include "classfile/systemDictionary.hpp"
44 #include "classfile/vmClasses.hpp"
45 #include "classfile/vmSymbols.hpp"
46 #include "gc/shared/gcTraceTime.inline.hpp"
47 #include "interpreter/bootstrapInfo.hpp"
48 #include "jfr/jfrEvents.hpp"
49 #include "jvm.h"
50 #include "logging/log.hpp"
51 #include "logging/logStream.hpp"
52 #include "memory/metaspaceClosure.hpp"
53 #include "memory/oopFactory.hpp"
54 #include "memory/resourceArea.hpp"
55 #include "memory/universe.hpp"
56 #include "oops/access.inline.hpp"
57 #include "oops/constantPool.inline.hpp"
58 #include "oops/fieldStreams.inline.hpp"
59 #include "oops/inlineKlass.inline.hpp"
60 #include "oops/instanceKlass.hpp"
61 #include "oops/klass.inline.hpp"
62 #include "oops/method.inline.hpp"
63 #include "oops/objArrayKlass.hpp"
64 #include "oops/objArrayOop.inline.hpp"
65 #include "oops/oop.inline.hpp"
66 #include "oops/oopHandle.inline.hpp"
67 #include "oops/symbol.hpp"
68 #include "oops/typeArrayKlass.hpp"
69 #include "prims/jvmtiExport.hpp"
70 #include "prims/methodHandles.hpp"
71 #include "runtime/arguments.hpp"
72 #include "runtime/atomicAccess.hpp"
73 #include "runtime/handles.inline.hpp"
74 #include "runtime/java.hpp"
75 #include "runtime/javaCalls.hpp"
76 #include "runtime/mutexLocker.hpp"
77 #include "runtime/os.hpp"
78 #include "runtime/sharedRuntime.hpp"
79 #include "runtime/signature.hpp"
80 #include "runtime/synchronizer.hpp"
81 #include "services/classLoadingService.hpp"
82 #include "services/diagnosticCommand.hpp"
83 #include "services/finalizerService.hpp"
84 #include "services/threadService.hpp"
85 #include "utilities/growableArray.hpp"
86 #include "utilities/macros.hpp"
87 #include "utilities/utf8.hpp"
88 #if INCLUDE_CDS
89 #include "classfile/systemDictionaryShared.hpp"
90 #endif
91 #if INCLUDE_JFR
92 #include "jfr/jfr.hpp"
93 #endif
94
95 class InvokeMethodKey : public StackObj {
96 private:
97 Symbol* _symbol;
172 CHECK_NULL);
173 return result.get_oop();
174 }
175
176 oop SystemDictionary::get_platform_class_loader_impl(TRAPS) {
177 JavaValue result(T_OBJECT);
178 InstanceKlass* class_loader_klass = vmClasses::ClassLoader_klass();
179 JavaCalls::call_static(&result,
180 class_loader_klass,
181 vmSymbols::getPlatformClassLoader_name(),
182 vmSymbols::void_classloader_signature(),
183 CHECK_NULL);
184 return result.get_oop();
185 }
186
187 // Helper function
188 inline ClassLoaderData* class_loader_data(Handle class_loader) {
189 return ClassLoaderData::class_loader_data(class_loader());
190 }
191
192 // These migrated value classes are loaded by the bootstrap class loader but are added to the initiating
193 // loaders automatically so that fields of these types can be found and potentially flattened during
194 // field layout.
195 static void add_migrated_value_classes(ClassLoaderData* cld) {
196 JavaThread* current = JavaThread::current();
197 auto add_klass = [&] (Symbol* classname) {
198 InstanceKlass* ik = SystemDictionary::find_instance_klass(current, classname, Handle(current, nullptr));
199 assert(ik != nullptr, "Must exist");
200 SystemDictionary::add_to_initiating_loader(current, ik, cld);
201 };
202
203 MonitorLocker mu1(SystemDictionary_lock);
204 vmSymbols::migrated_class_names_do(add_klass);
205 }
206
207 ClassLoaderData* SystemDictionary::register_loader(Handle class_loader, bool create_mirror_cld) {
208 if (create_mirror_cld) {
209 // Add a new class loader data to the graph.
210 return ClassLoaderDataGraph::add(class_loader, true);
211 } else {
212 if (class_loader() == nullptr) {
213 return ClassLoaderData::the_null_class_loader_data();
214 } else {
215 bool created = false;
216 ClassLoaderData* cld = ClassLoaderDataGraph::find_or_create(class_loader, created);
217 if (created && Arguments::enable_preview()) {
218 if (CDSConfig::is_using_aot_linked_classes() && java_system_loader() == nullptr) {
219 // We are inside AOTLinkedClassBulkLoader::preload_classes().
220 //
221 // AOTLinkedClassBulkLoader will automatically initiate the loading of all archived
222 // public classes from the boot loader into platform/system loaders, so there's
223 // no need to call add_migrated_value_classes().
224 } else {
225 add_migrated_value_classes(cld);
226 }
227 }
228 return cld;
229 }
230 }
231 }
232
233 void SystemDictionary::set_system_loader(ClassLoaderData *cld) {
234 if (_java_system_loader.is_empty()) {
235 _java_system_loader = cld->class_loader_handle();
236 } else {
237 assert(_java_system_loader.resolve() == cld->class_loader(), "sanity");
238 }
239 }
240
241 void SystemDictionary::set_platform_loader(ClassLoaderData *cld) {
242 if (_java_platform_loader.is_empty()) {
243 _java_platform_loader = cld->class_loader_handle();
244 } else {
245 assert(_java_platform_loader.resolve() == cld->class_loader(), "sanity");
246 }
247 }
248
249 // ----------------------------------------------------------------------------
417 }
418 } else {
419 k = Universe::typeArrayKlass(t);
420 k = k->array_klass(ndims, CHECK_NULL);
421 }
422 return k;
423 }
424
425 static inline void log_circularity_error(Symbol* name, PlaceholderEntry* probe) {
426 LogTarget(Debug, class, load, placeholders) lt;
427 if (lt.is_enabled()) {
428 ResourceMark rm;
429 LogStream ls(lt);
430 ls.print("ClassCircularityError detected for placeholder entry %s", name->as_C_string());
431 probe->print_on(&ls);
432 ls.cr();
433 }
434 }
435
436 // Must be called for any superclass or superinterface resolution
437 // during class definition, or may be called for inline field layout processing
438 // to detect class circularity errors.
439 // superinterface callers:
440 // parse_interfaces - from defineClass
441 // superclass callers:
442 // ClassFileParser - from defineClass
443 // load_shared_class - while loading a class from shared archive
444 // resolve_instance_class_or_null:
445 // via: handle_parallel_super_load
446 // when resolving a class that has an existing placeholder with
447 // a saved superclass [i.e. a defineClass is currently in progress]
448 // If another thread is trying to resolve the class, it must do
449 // superclass checks on its own thread to catch class circularity and
450 // to avoid deadlock.
451 // inline field layout callers:
452 // The field's class must be loaded to determine layout.
453 //
454 // resolve_with_circularity_detection adds a DETECT_CIRCULARITY placeholder to the placeholder table before calling
455 // resolve_instance_class_or_null. ClassCircularityError is detected when a DETECT_CIRCULARITY or LOAD_INSTANCE
456 // placeholder for the same thread, class, and classloader is found.
457 // This can be seen with logging option: -Xlog:class+load+placeholders=debug.
458 //
459 InstanceKlass* SystemDictionary::resolve_with_circularity_detection(Symbol* class_name,
460 Symbol* next_name,
461 Handle class_loader,
462 bool is_superclass,
463 TRAPS) {
464
465 assert(next_name != nullptr, "null superclass for resolving");
466 assert(!Signature::is_array(next_name), "invalid superclass name");
467
468 ClassLoaderData* loader_data = class_loader_data(class_loader);
469
470 if (is_superclass) {
471 InstanceKlass* klassk = loader_data->dictionary()->find_class(THREAD, class_name);
472 if (klassk != nullptr) {
473 // We can come here for two reasons:
474 // (a) RedefineClasses -- the class is already loaded
475 // (b) Rarely, the class might have been loaded by a parallel thread
476 // We can do a quick check against the already assigned superclass's name and loader.
477 InstanceKlass* superk = klassk->super();
478 if (superk != nullptr &&
479 superk->name() == next_name &&
480 superk->class_loader() == class_loader()) {
481 return superk;
482 }
483 }
484 }
485
486 // can't throw error holding a lock
487 bool throw_circularity_error = false;
488 {
489 MutexLocker mu(THREAD, SystemDictionary_lock);
490
491 // Must check ClassCircularity before resolving next_name (superclass, interface, field types or speculatively preloaded argument types).
492 PlaceholderEntry* probe = PlaceholderTable::get_entry(class_name, loader_data);
493 if (probe != nullptr && probe->check_seen_thread(THREAD, PlaceholderTable::DETECT_CIRCULARITY)) {
494 log_circularity_error(class_name, probe);
495 throw_circularity_error = true;
496 }
497
498 // Make sure there's a placeholder for the class_name before resolving.
499 // This is used as a claim that this thread is currently loading superclass/classloader
500 // and for ClassCircularity checks.
501 if (!throw_circularity_error) {
502 // Be careful not to exit resolve_with_circularity_detection without removing this placeholder.
503 PlaceholderEntry* newprobe = PlaceholderTable::find_and_add(class_name,
504 loader_data,
505 PlaceholderTable::DETECT_CIRCULARITY,
506 next_name, THREAD);
507 }
508 }
509
510 if (throw_circularity_error) {
511 ResourceMark rm(THREAD);
512 THROW_MSG_NULL(vmSymbols::java_lang_ClassCircularityError(), class_name->as_C_string());
513 }
514
515 // Resolve the superclass, superinterface, field type or speculatively preloaded argument types and check results on return.
516 InstanceKlass* superk =
517 SystemDictionary::resolve_instance_class_or_null(next_name,
518 class_loader,
519 THREAD);
520
521 // Clean up placeholder entry.
522 {
523 MutexLocker mu(THREAD, SystemDictionary_lock);
524 PlaceholderTable::find_and_remove(class_name, loader_data, PlaceholderTable::DETECT_CIRCULARITY, THREAD);
525 SystemDictionary_lock->notify_all();
526 }
527
528 // Check for pending exception or null superk, and throw exception
529 if (HAS_PENDING_EXCEPTION || superk == nullptr) {
530 handle_resolution_exception(next_name, true, CHECK_NULL);
531 }
532
533 return superk;
534 }
535
933
934 InstanceKlass* SystemDictionary::resolve_from_stream(ClassFileStream* st,
935 Symbol* class_name,
936 Handle class_loader,
937 const ClassLoadInfo& cl_info,
938 TRAPS) {
939 if (cl_info.is_hidden()) {
940 return resolve_hidden_class_from_stream(st, class_name, class_loader, cl_info, CHECK_NULL);
941 } else {
942 return resolve_class_from_stream(st, class_name, class_loader, cl_info, CHECK_NULL);
943 }
944 }
945
946
947 #if INCLUDE_CDS
948 // Check if a shared class can be loaded by the specific classloader.
949 bool SystemDictionary::is_shared_class_visible(Symbol* class_name,
950 InstanceKlass* ik,
951 PackageEntry* pkg_entry,
952 Handle class_loader) {
953
954 assert(!ModuleEntryTable::javabase_moduleEntry()->is_patched(),
955 "Cannot use sharing if java.base is patched");
956
957 // (1) Check if we are loading into the same loader as in dump time.
958
959 if (ik->defined_by_boot_loader()) {
960 if (class_loader() != nullptr) {
961 return false;
962 }
963 } else if (ik->defined_by_platform_loader()) {
964 if (class_loader() != java_platform_loader()) {
965 return false;
966 }
967 } else if (ik->defined_by_app_loader()) {
968 if (class_loader() != java_system_loader()) {
969 return false;
970 }
971 } else {
972 // ik was loaded by a custom loader during dump time
973 if (class_loader_data(class_loader)->is_builtin_class_loader_data()) {
1089 class_loader, true,
1090 CHECK_false);
1091 if (!check_super) {
1092 return false;
1093 }
1094 }
1095
1096 Array<InstanceKlass*>* interfaces = ik->local_interfaces();
1097 int num_interfaces = interfaces->length();
1098 for (int index = 0; index < num_interfaces; index++) {
1099 bool check_interface = check_shared_class_super_type(ik, interfaces->at(index), class_loader, false,
1100 CHECK_false);
1101 if (!check_interface) {
1102 return false;
1103 }
1104 }
1105
1106 return true;
1107 }
1108
1109 // Pre-load class referred to in non-static null-free instance field. These fields trigger MANDATORY loading.
1110 // Some pre-loading does not fail fatally
1111 bool SystemDictionary::preload_from_null_free_field(InstanceKlass* ik, Handle class_loader, Symbol* sig, int field_index, TRAPS) {
1112 TempNewSymbol name = Signature::strip_envelope(sig);
1113 log_info(class, preload)("Preloading of class %s during loading of shared class %s. "
1114 "Cause: a null-free non-static field is declared with this type",
1115 name->as_C_string(), ik->name()->as_C_string());
1116 InstanceKlass* real_k = SystemDictionary::resolve_with_circularity_detection(ik->name(), name,
1117 class_loader, false, CHECK_false);
1118 if (HAS_PENDING_EXCEPTION) {
1119 log_info(class, preload)("Preloading of class %s during loading of class %s "
1120 "(cause: null-free non-static field) failed: %s",
1121 name->as_C_string(), ik->name()->as_C_string(),
1122 PENDING_EXCEPTION->klass()->name()->as_C_string());
1123 return false; // Exception is still pending
1124 }
1125
1126 InstanceKlass* k = ik->get_inline_type_field_klass_or_null(field_index);
1127 if (real_k != k) {
1128 // oops, the app has substituted a different version of k! Does not fail fatally
1129 log_info(class, preload)("Preloading of class %s during loading of shared class %s "
1130 "(cause: null-free non-static field) failed : "
1131 "app substituted a different version of %s",
1132 name->as_C_string(), ik->name()->as_C_string(),
1133 name->as_C_string());
1134 return false;
1135 }
1136 log_info(class, preload)("Preloading of class %s during loading of shared class %s "
1137 "(cause: null-free non-static field) succeeded",
1138 name->as_C_string(), ik->name()->as_C_string());
1139
1140 assert(real_k != nullptr, "Sanity check");
1141 InstanceKlass::check_can_be_annotated_with_NullRestricted(real_k, ik->name(), CHECK_false);
1142
1143 return true;
1144 }
1145
1146 // Tries to pre-load classes referred to in non-static nullable instance fields if they are found in the
1147 // loadable descriptors attribute. If loading fails, we can fail silently.
1148 void SystemDictionary::try_preload_from_loadable_descriptors(InstanceKlass* ik, Handle class_loader, Symbol* sig, int field_index, TRAPS) {
1149 TempNewSymbol name = Signature::strip_envelope(sig);
1150 if (name != ik->name() && ik->is_class_in_loadable_descriptors_attribute(sig)) {
1151 log_info(class, preload)("Preloading of class %s during loading of shared class %s. "
1152 "Cause: field type in LoadableDescriptors attribute",
1153 name->as_C_string(), ik->name()->as_C_string());
1154 InstanceKlass* real_k = SystemDictionary::resolve_with_circularity_detection(ik->name(), name,
1155 class_loader, false, THREAD);
1156 if (HAS_PENDING_EXCEPTION) {
1157 CLEAR_PENDING_EXCEPTION;
1158 }
1159
1160 InstanceKlass* k = ik->get_inline_type_field_klass_or_null(field_index);
1161 if (real_k != k) {
1162 // oops, the app has substituted a different version of k!
1163 log_info(class, preload)("Preloading of class %s during loading of shared class %s "
1164 "(cause: field type in LoadableDescriptors attribute) failed : "
1165 "app substituted a different version of %s",
1166 name->as_C_string(), ik->name()->as_C_string(),
1167 k->name()->as_C_string());
1168 return;
1169 } else if (real_k != nullptr) {
1170 log_info(class, preload)("Preloading of class %s during loading of shared class %s "
1171 "(cause: field type in LoadableDescriptors attribute) succeeded",
1172 name->as_C_string(), ik->name()->as_C_string());
1173 }
1174 }
1175 }
1176
1177
1178 InstanceKlass* SystemDictionary::load_shared_class(InstanceKlass* ik,
1179 Handle class_loader,
1180 Handle protection_domain,
1181 const ClassFileStream *cfs,
1182 PackageEntry* pkg_entry,
1183 TRAPS) {
1184 assert(ik != nullptr, "sanity");
1185 assert(ik->in_aot_cache(), "sanity");
1186 assert(!ik->is_unshareable_info_restored(), "shared class can be restored only once");
1187 assert(AtomicAccess::add(&ik->_shared_class_load_count, 1) == 1, "shared class loaded more than once");
1188 Symbol* class_name = ik->name();
1189
1190 if (!is_shared_class_visible(class_name, ik, pkg_entry, class_loader)) {
1191 ik->set_shared_loading_failed();
1192 return nullptr;
1193 }
1194
1195 bool check = check_shared_class_super_types(ik, class_loader, CHECK_NULL);
1196 if (!check) {
1197 ik->set_shared_loading_failed();
1198 return nullptr;
1199 }
1200
1201 if (ik->has_inline_type_fields()) {
1202 for (AllFieldStream fs(ik); !fs.done(); fs.next()) {
1203 if (fs.access_flags().is_static()) continue;
1204
1205 Symbol* sig = fs.signature();
1206 int field_index = fs.index();
1207
1208 if (fs.is_null_free_inline_type()) {
1209 // A false return means that the class didn't load for other reasons than an exception.
1210 bool check = preload_from_null_free_field(ik, class_loader, sig, field_index, CHECK_NULL);
1211 if (!check) {
1212 ik->set_shared_loading_failed();
1213 return nullptr;
1214 }
1215 } else if (Signature::has_envelope(sig)) {
1216 // Pending exceptions are cleared so we can fail silently
1217 try_preload_from_loadable_descriptors(ik, class_loader, sig, field_index, CHECK_NULL);
1218 }
1219 }
1220 }
1221
1222 InstanceKlass* new_ik = nullptr;
1223 // CFLH check is skipped for VM hidden classes (see KlassFactory::create_from_stream).
1224 // It will be skipped for shared VM hidden lambda proxy classes.
1225 if (!ik->is_hidden()) {
1226 new_ik = KlassFactory::check_shared_class_file_load_hook(
1227 ik, class_name, class_loader, protection_domain, cfs, CHECK_NULL);
1228 }
1229 if (new_ik != nullptr) {
1230 // The class is changed by CFLH. Return the new class. The shared class is
1231 // not used.
1232 return new_ik;
1233 }
1234
1235 // Adjust methods to recover missing data. They need addresses for
1236 // interpreter entry points and their default native method address
1237 // must be reset.
1238
1239 // Shared classes are all currently loaded by either the bootstrap or
1240 // internal parallel class loaders, so this will never cause a deadlock
1241 // on a custom class loader lock.
1242 // Since this class is already locked with parallel capable class
1243 // loaders, including the bootstrap loader via the placeholder table,
1244 // this lock is currently a nop.
1245
1246 ClassLoaderData* loader_data = class_loader_data(class_loader);
1247 {
1248 HandleMark hm(THREAD);
1249 Handle lockObject = get_loader_lock_or_null(class_loader);
1250 ObjectLocker ol(lockObject, THREAD);
1251 // prohibited package check assumes all classes loaded from archive call
1252 // restore_unshareable_info which calls ik->set_package()
1253 ik->restore_unshareable_info(loader_data, protection_domain, pkg_entry, CHECK_NULL);
1254 }
1255
1256 load_shared_class_misc(ik, loader_data);
1257
1258 return ik;
1259 }
1260
1261 void SystemDictionary::load_shared_class_misc(InstanceKlass* ik, ClassLoaderData* loader_data) {
1262 ik->print_class_load_logging(loader_data, nullptr, nullptr);
1263
1264 // For boot loader, ensure that GetSystemPackage knows that a class in this
1265 // package was loaded.
1266 if (loader_data->is_the_null_class_loader_data()) {
1267 s2 path_index = ik->shared_classpath_index();
1268 ik->set_classpath_index(path_index);
1269 }
1270
1271 // notify a class loaded from shared object
1272 ClassLoadingService::notify_class_loaded(ik, true /* shared class */);
1273
1274 if (CDSConfig::is_dumping_final_static_archive()) {
1275 SystemDictionaryShared::init_dumptime_info_from_preimage(ik);
1276 }
1277 }
1819 }
1820 }
1821
1822 // Update class loader data dictionary - done after check_constraint and add_to_hierarchy
1823 // have been called.
1824 void SystemDictionary::update_dictionary(JavaThread* current,
1825 InstanceKlass* k,
1826 ClassLoaderData* loader_data) {
1827 MonitorLocker mu1(SystemDictionary_lock);
1828
1829 // Make a new dictionary entry.
1830 Symbol* name = k->name();
1831 Dictionary* dictionary = loader_data->dictionary();
1832 InstanceKlass* sd_check = dictionary->find_class(current, name);
1833 if (sd_check == nullptr) {
1834 dictionary->add_klass(current, name, k);
1835 }
1836 mu1.notify_all();
1837 }
1838
1839 // Indicate that loader_data has initiated the loading of class k, which
1840 // has already been defined by a parent loader.
1841 // This API is used by AOTLinkedClassBulkLoader and to register boxing
1842 // classes from java.lang in all class loaders to enable more value
1843 // classes optimizations
1844 void SystemDictionary::add_to_initiating_loader(JavaThread* current,
1845 InstanceKlass* k,
1846 ClassLoaderData* loader_data) {
1847 assert_locked_or_safepoint(SystemDictionary_lock);
1848 Symbol* name = k->name();
1849 Dictionary* dictionary = loader_data->dictionary();
1850 assert(k->is_loaded(), "must be");
1851 assert(k->class_loader_data() != loader_data, "only for classes defined by a parent loader");
1852 if (dictionary->find_class(current, name) == nullptr) {
1853 dictionary->add_klass(current, name, k);
1854 }
1855 }
1856
1857 // Try to find a class name using the loader constraints. The
1858 // loader constraints might know about a class that isn't fully loaded
1859 // yet and these will be ignored.
1860 Klass* SystemDictionary::find_constrained_instance_or_array_klass(
1861 Thread* current, Symbol* class_name, Handle class_loader) {
1862
1863 // First see if it has been loaded directly.
1864 Klass* klass = find_instance_or_array_klass(current, class_name, class_loader);
1865 if (klass != nullptr)
1866 return klass;
1867
1868 // Now look to see if it has been loaded elsewhere, and is subject to
1869 // a loader constraint that would require this loader to return the
1870 // klass that is already loaded.
1871 if (Signature::is_array(class_name)) {
1872 // For array classes, their Klass*s are not kept in the
1873 // constraint table. The element Klass*s are.
1874 SignatureStream ss(class_name, false);
1875 int ndims = ss.skip_array_prefix(); // skip all '['s
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