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 *
23 */
24
25 #include "cds/aotClassLocation.hpp"
26 #include "cds/cdsConfig.hpp"
27 #include "cds/heapShared.hpp"
28 #include "classfile/classFileParser.hpp"
29 #include "classfile/classFileStream.hpp"
30 #include "classfile/classLoader.hpp"
31 #include "classfile/classLoaderData.inline.hpp"
32 #include "classfile/classLoaderDataGraph.inline.hpp"
33 #include "classfile/classLoaderExt.hpp"
34 #include "classfile/classLoadInfo.hpp"
35 #include "classfile/dictionary.hpp"
36 #include "classfile/javaClasses.inline.hpp"
37 #include "classfile/klassFactory.hpp"
38 #include "classfile/loaderConstraints.hpp"
39 #include "classfile/packageEntry.hpp"
40 #include "classfile/placeholders.hpp"
41 #include "classfile/resolutionErrors.hpp"
42 #include "classfile/stringTable.hpp"
43 #include "classfile/symbolTable.hpp"
44 #include "classfile/systemDictionary.hpp"
45 #include "classfile/vmClasses.hpp"
46 #include "classfile/vmSymbols.hpp"
47 #include "gc/shared/gcTraceTime.inline.hpp"
48 #include "interpreter/bootstrapInfo.hpp"
49 #include "jfr/jfrEvents.hpp"
50 #include "jvm.h"
51 #include "logging/log.hpp"
52 #include "logging/logStream.hpp"
53 #include "memory/metaspaceClosure.hpp"
54 #include "memory/oopFactory.hpp"
55 #include "memory/resourceArea.hpp"
56 #include "memory/universe.hpp"
57 #include "oops/access.inline.hpp"
58 #include "oops/fieldStreams.inline.hpp"
59 #include "oops/instanceKlass.hpp"
60 #include "oops/klass.inline.hpp"
61 #include "oops/method.inline.hpp"
62 #include "oops/objArrayKlass.hpp"
63 #include "oops/objArrayOop.inline.hpp"
64 #include "oops/oop.inline.hpp"
65 #include "oops/oop.hpp"
66 #include "oops/oopHandle.hpp"
67 #include "oops/oopHandle.inline.hpp"
68 #include "oops/symbol.hpp"
69 #include "oops/typeArrayKlass.hpp"
70 #include "oops/inlineKlass.inline.hpp"
71 #include "prims/jvmtiExport.hpp"
72 #include "prims/methodHandles.hpp"
73 #include "runtime/arguments.hpp"
74 #include "runtime/atomic.hpp"
75 #include "runtime/handles.inline.hpp"
76 #include "runtime/java.hpp"
77 #include "runtime/javaCalls.hpp"
78 #include "runtime/mutexLocker.hpp"
79 #include "runtime/os.hpp"
80 #include "runtime/sharedRuntime.hpp"
81 #include "runtime/signature.hpp"
82 #include "runtime/synchronizer.hpp"
83 #include "services/classLoadingService.hpp"
84 #include "services/diagnosticCommand.hpp"
85 #include "services/finalizerService.hpp"
86 #include "services/threadService.hpp"
87 #include "utilities/growableArray.hpp"
88 #include "utilities/macros.hpp"
89 #include "utilities/utf8.hpp"
90 #if INCLUDE_CDS
91 #include "classfile/systemDictionaryShared.hpp"
92 #endif
93 #if INCLUDE_JFR
94 #include "jfr/jfr.hpp"
95 #endif
96
97 class InvokeMethodKey : public StackObj {
98 private:
99 Symbol* _symbol;
100 intptr_t _iid;
101
102 public:
103 InvokeMethodKey(Symbol* symbol, intptr_t iid) :
104 _symbol(symbol),
105 _iid(iid) {}
106
107 static bool key_comparison(InvokeMethodKey const &k1, InvokeMethodKey const &k2){
108 return k1._symbol == k2._symbol && k1._iid == k2._iid;
109 }
110
111 static unsigned int compute_hash(const InvokeMethodKey &k) {
112 Symbol* sym = k._symbol;
113 intptr_t iid = k._iid;
114 unsigned int hash = (unsigned int) sym -> identity_hash();
115 return (unsigned int) (hash ^ iid);
116 }
117
118 };
119
120 using InvokeMethodIntrinsicTable = ResourceHashtable<InvokeMethodKey, Method*, 139, AnyObj::C_HEAP, mtClass,
121 InvokeMethodKey::compute_hash, InvokeMethodKey::key_comparison>;
122 static InvokeMethodIntrinsicTable* _invoke_method_intrinsic_table;
123 using InvokeMethodTypeTable = ResourceHashtable<SymbolHandle, OopHandle, 139, AnyObj::C_HEAP, mtClass, SymbolHandle::compute_hash>;
124 static InvokeMethodTypeTable* _invoke_method_type_table;
125
126 OopHandle SystemDictionary::_java_system_loader;
127 OopHandle SystemDictionary::_java_platform_loader;
128
129 // ----------------------------------------------------------------------------
130 // Java-level SystemLoader and PlatformLoader
131 oop SystemDictionary::java_system_loader() {
132 return _java_system_loader.resolve();
133 }
134
135 oop SystemDictionary::java_platform_loader() {
136 return _java_platform_loader.resolve();
137 }
138
139 void SystemDictionary::compute_java_loaders(TRAPS) {
140 if (_java_platform_loader.is_empty()) {
141 oop platform_loader = get_platform_class_loader_impl(CHECK);
142 _java_platform_loader = OopHandle(Universe::vm_global(), platform_loader);
143 } else {
144 // It must have been restored from the archived module graph
145 assert(CDSConfig::is_using_archive(), "must be");
146 assert(CDSConfig::is_using_full_module_graph(), "must be");
147 DEBUG_ONLY(
148 oop platform_loader = get_platform_class_loader_impl(CHECK);
149 assert(_java_platform_loader.resolve() == platform_loader, "must be");
150 )
151 }
152
153 if (_java_system_loader.is_empty()) {
154 oop system_loader = get_system_class_loader_impl(CHECK);
155 _java_system_loader = OopHandle(Universe::vm_global(), system_loader);
156 } else {
157 // It must have been restored from the archived module graph
158 assert(CDSConfig::is_using_archive(), "must be");
159 assert(CDSConfig::is_using_full_module_graph(), "must be");
160 DEBUG_ONLY(
161 oop system_loader = get_system_class_loader_impl(CHECK);
162 assert(_java_system_loader.resolve() == system_loader, "must be");
163 )
164 }
165 }
166
167 oop SystemDictionary::get_system_class_loader_impl(TRAPS) {
168 JavaValue result(T_OBJECT);
169 InstanceKlass* class_loader_klass = vmClasses::ClassLoader_klass();
170 JavaCalls::call_static(&result,
171 class_loader_klass,
172 vmSymbols::getSystemClassLoader_name(),
173 vmSymbols::void_classloader_signature(),
174 CHECK_NULL);
175 return result.get_oop();
176 }
177
178 oop SystemDictionary::get_platform_class_loader_impl(TRAPS) {
179 JavaValue result(T_OBJECT);
180 InstanceKlass* class_loader_klass = vmClasses::ClassLoader_klass();
181 JavaCalls::call_static(&result,
182 class_loader_klass,
183 vmSymbols::getPlatformClassLoader_name(),
184 vmSymbols::void_classloader_signature(),
185 CHECK_NULL);
186 return result.get_oop();
187 }
188
189 // Helper function
190 inline ClassLoaderData* class_loader_data(Handle class_loader) {
191 return ClassLoaderData::class_loader_data(class_loader());
192 }
193
194 // These migrated value classes are loaded by the bootstrap class loader but are added to the initiating
195 // loaders automatically so that fields of these types can be found and potentially flattened during
196 // field layout.
197 static void add_migrated_value_classes(ClassLoaderData* cld) {
198 JavaThread* current = JavaThread::current();
199 auto add_klass = [&] (Symbol* classname) {
200 InstanceKlass* ik = SystemDictionary::find_instance_klass(current, classname, Handle(current, nullptr));
201 assert(ik != nullptr, "Must exist");
202 SystemDictionary::add_to_initiating_loader(current, ik, cld);
203 };
204
205 MonitorLocker mu1(SystemDictionary_lock);
206 vmSymbols::migrated_class_names_do(add_klass);
207 }
208
209 ClassLoaderData* SystemDictionary::register_loader(Handle class_loader, bool create_mirror_cld) {
210 if (create_mirror_cld) {
211 // Add a new class loader data to the graph.
212 return ClassLoaderDataGraph::add(class_loader, true);
213 } else {
214 if (class_loader() == nullptr) {
215 return ClassLoaderData::the_null_class_loader_data();
216 } else {
217 ClassLoaderData* cld = ClassLoaderDataGraph::find_or_create(class_loader);
218 if (EnableValhalla) {
219 add_migrated_value_classes(cld);
220 }
221 return cld;
222 }
223 }
224 }
225
226 void SystemDictionary::set_system_loader(ClassLoaderData *cld) {
227 assert(_java_system_loader.is_empty(), "already set!");
228 _java_system_loader = cld->class_loader_handle();
229
230 }
231
232 void SystemDictionary::set_platform_loader(ClassLoaderData *cld) {
233 assert(_java_platform_loader.is_empty(), "already set!");
234 _java_platform_loader = cld->class_loader_handle();
235 }
236
237 // ----------------------------------------------------------------------------
238 // Parallel class loading check
239
240 static bool is_parallelCapable(Handle class_loader) {
241 if (class_loader.is_null()) return true;
242 return java_lang_ClassLoader::parallelCapable(class_loader());
243 }
244 // ----------------------------------------------------------------------------
245 // ParallelDefineClass flag does not apply to bootclass loader
246 static bool is_parallelDefine(Handle class_loader) {
247 if (class_loader.is_null()) return false;
248 if (AllowParallelDefineClass && java_lang_ClassLoader::parallelCapable(class_loader())) {
249 return true;
250 }
251 return false;
252 }
253
254 // Returns true if the passed class loader is the builtin application class loader
255 // or a custom system class loader. A customer system class loader can be
256 // specified via -Djava.system.class.loader.
257 bool SystemDictionary::is_system_class_loader(oop class_loader) {
258 if (class_loader == nullptr) {
259 return false;
260 }
261 return (class_loader->klass() == vmClasses::jdk_internal_loader_ClassLoaders_AppClassLoader_klass() ||
262 class_loader == _java_system_loader.peek());
263 }
264
265 // Returns true if the passed class loader is the platform class loader.
266 bool SystemDictionary::is_platform_class_loader(oop class_loader) {
267 if (class_loader == nullptr) {
268 return false;
269 }
270 return (class_loader->klass() == vmClasses::jdk_internal_loader_ClassLoaders_PlatformClassLoader_klass());
271 }
272
273 Handle SystemDictionary::get_loader_lock_or_null(Handle class_loader) {
274 // If class_loader is null or parallelCapable, the JVM doesn't acquire a lock while loading.
275 if (is_parallelCapable(class_loader)) {
276 return Handle();
277 } else {
278 return class_loader;
279 }
280 }
281
282 // ----------------------------------------------------------------------------
283 // Resolving of classes
284
285 Symbol* SystemDictionary::class_name_symbol(const char* name, Symbol* exception, TRAPS) {
286 if (name == nullptr) {
287 THROW_MSG_NULL(exception, "No class name given");
288 }
289 size_t name_len = strlen(name);
290 if (name_len > static_cast<size_t>(Symbol::max_length())) {
291 // It's impossible to create this class; the name cannot fit
292 // into the constant pool. If necessary report an abridged name
293 // in the exception message.
294 if (name_len > static_cast<size_t>(MaxStringPrintSize)) {
295 Exceptions::fthrow(THREAD_AND_LOCATION, exception,
296 "Class name exceeds maximum length of %d: %.*s ... (%zu characters omitted) ... %.*s",
297 Symbol::max_length(),
298 MaxStringPrintSize / 2,
299 name,
300 name_len - 2 * (MaxStringPrintSize / 2), // allows for odd value
301 MaxStringPrintSize / 2,
302 name + name_len - MaxStringPrintSize / 2);
303 }
304 else {
305 Exceptions::fthrow(THREAD_AND_LOCATION, exception,
306 "Class name exceeds maximum length of %d: %s",
307 Symbol::max_length(),
308 name);
309 }
310 return nullptr;
311 }
312 // Callers should ensure that the name is never an illegal UTF8 string.
313 assert(UTF8::is_legal_utf8((const unsigned char*)name, name_len, false),
314 "Class name is not a valid utf8 string.");
315
316 // Make a new symbol for the class name.
317 return SymbolTable::new_symbol(name);
318 }
319
320 #ifdef ASSERT
321 // Used to verify that class loading succeeded in adding k to the dictionary.
322 static void verify_dictionary_entry(Symbol* class_name, InstanceKlass* k) {
323 MutexLocker mu(SystemDictionary_lock);
324 ClassLoaderData* loader_data = k->class_loader_data();
325 Dictionary* dictionary = loader_data->dictionary();
326 assert(class_name == k->name(), "Must be the same");
327 InstanceKlass* kk = dictionary->find_class(JavaThread::current(), class_name);
328 assert(kk == k, "should be present in dictionary");
329 }
330 #endif
331
332 static void handle_resolution_exception(Symbol* class_name, bool throw_error, TRAPS) {
333 if (HAS_PENDING_EXCEPTION) {
334 // If we have a pending exception we forward it to the caller, unless throw_error is true,
335 // in which case we have to check whether the pending exception is a ClassNotFoundException,
336 // and convert it to a NoClassDefFoundError and chain the original ClassNotFoundException.
337 if (throw_error && PENDING_EXCEPTION->is_a(vmClasses::ClassNotFoundException_klass())) {
338 ResourceMark rm(THREAD);
339 Handle e(THREAD, PENDING_EXCEPTION);
340 CLEAR_PENDING_EXCEPTION;
341 THROW_MSG_CAUSE(vmSymbols::java_lang_NoClassDefFoundError(), class_name->as_C_string(), e);
342 } else {
343 return; // the caller will throw the incoming exception
344 }
345 }
346 // If the class is not found, ie, caller has checked that klass is null, throw the appropriate
347 // error or exception depending on the value of throw_error.
348 ResourceMark rm(THREAD);
349 if (throw_error) {
350 THROW_MSG(vmSymbols::java_lang_NoClassDefFoundError(), class_name->as_C_string());
351 } else {
352 THROW_MSG(vmSymbols::java_lang_ClassNotFoundException(), class_name->as_C_string());
353 }
354 }
355
356 // Forwards to resolve_or_null
357
358 Klass* SystemDictionary::resolve_or_fail(Symbol* class_name, Handle class_loader,
359 bool throw_error, TRAPS) {
360 Klass* klass = resolve_or_null(class_name, class_loader, THREAD);
361 // Check for pending exception or null klass, and throw exception
362 if (HAS_PENDING_EXCEPTION || klass == nullptr) {
363 handle_resolution_exception(class_name, throw_error, CHECK_NULL);
364 }
365 return klass;
366 }
367
368 // Forwards to resolve_array_class_or_null or resolve_instance_class_or_null
369
370 Klass* SystemDictionary::resolve_or_null(Symbol* class_name, Handle class_loader, TRAPS) {
371 if (Signature::is_array(class_name)) {
372 return resolve_array_class_or_null(class_name, class_loader, THREAD);
373 } else {
374 assert(class_name != nullptr && !Signature::is_array(class_name), "must be");
375 if (Signature::has_envelope(class_name)) {
376 ResourceMark rm(THREAD);
377 // Ignore wrapping L and ; (and Q and ; for value types).
378 TempNewSymbol name = SymbolTable::new_symbol(class_name->as_C_string() + 1,
379 class_name->utf8_length() - 2);
380 return resolve_instance_class_or_null(name, class_loader, THREAD);
381 } else {
382 return resolve_instance_class_or_null(class_name, class_loader, THREAD);
383 }
384 }
385 }
386
387 // Forwards to resolve_instance_class_or_null
388
389 Klass* SystemDictionary::resolve_array_class_or_null(Symbol* class_name,
390 Handle class_loader,
391 TRAPS) {
392 assert(Signature::is_array(class_name), "must be array");
393 ResourceMark rm(THREAD);
394 SignatureStream ss(class_name, false);
395 int ndims = ss.skip_array_prefix(); // skip all '['s
396 Klass* k = nullptr;
397 BasicType t = ss.type();
398 if (ss.has_envelope()) {
399 Symbol* obj_class = ss.as_symbol();
400 k = SystemDictionary::resolve_instance_class_or_null(obj_class,
401 class_loader,
402 CHECK_NULL);
403 if (k != nullptr) {
404 k = k->array_klass(ndims, CHECK_NULL);
405 }
406 } else {
407 k = Universe::typeArrayKlass(t);
408 k = k->array_klass(ndims, CHECK_NULL);
409 }
410 return k;
411 }
412
413 static inline void log_circularity_error(Symbol* name, PlaceholderEntry* probe) {
414 LogTarget(Debug, class, load, placeholders) lt;
415 if (lt.is_enabled()) {
416 ResourceMark rm;
417 LogStream ls(lt);
418 ls.print("ClassCircularityError detected for placeholder entry %s", name->as_C_string());
419 probe->print_on(&ls);
420 ls.cr();
421 }
422 }
423
424 // Must be called for any superclass or superinterface resolution
425 // during class definition to allow class circularity checking
426 // superinterface callers:
427 // parse_interfaces - from defineClass
428 // superclass callers:
429 // ClassFileParser - from defineClass
430 // load_shared_class - while loading a class from shared archive
431 // resolve_instance_class_or_null:
432 // via: handle_parallel_super_load
433 // when resolving a class that has an existing placeholder with
434 // a saved superclass [i.e. a defineClass is currently in progress]
435 // If another thread is trying to resolve the class, it must do
436 // superclass checks on its own thread to catch class circularity and
437 // to avoid deadlock.
438 //
439 // resolve_with_circularity_detection adds a DETECT_CIRCULARITY placeholder to the placeholder table before calling
440 // resolve_instance_class_or_null. ClassCircularityError is detected when a DETECT_CIRCULARITY or LOAD_INSTANCE
441 // placeholder for the same thread, class, classloader is found.
442 // This can be seen with logging option: -Xlog:class+load+placeholders=debug.
443 //
444 InstanceKlass* SystemDictionary::resolve_with_circularity_detection(Symbol* class_name,
445 Symbol* next_name,
446 Handle class_loader,
447 bool is_superclass,
448 TRAPS) {
449
450 assert(next_name != nullptr, "null superclass for resolving");
451 assert(!Signature::is_array(next_name), "invalid superclass name");
452
453 ClassLoaderData* loader_data = class_loader_data(class_loader);
454
455 if (is_superclass) {
456 InstanceKlass* klassk = loader_data->dictionary()->find_class(THREAD, class_name);
457 if (klassk != nullptr) {
458 // We can come here for two reasons:
459 // (a) RedefineClasses -- the class is already loaded
460 // (b) Rarely, the class might have been loaded by a parallel thread
461 // We can do a quick check against the already assigned superclass's name and loader.
462 InstanceKlass* superk = klassk->java_super();
463 if (superk != nullptr &&
464 superk->name() == next_name &&
465 superk->class_loader() == class_loader()) {
466 return superk;
467 }
468 }
469 }
470
471 // can't throw error holding a lock
472 bool throw_circularity_error = false;
473 {
474 MutexLocker mu(THREAD, SystemDictionary_lock);
475
476 // Must check ClassCircularity before resolving next_name (superclass or interface).
477 PlaceholderEntry* probe = PlaceholderTable::get_entry(class_name, loader_data);
478 if (probe != nullptr && probe->check_seen_thread(THREAD, PlaceholderTable::DETECT_CIRCULARITY)) {
479 log_circularity_error(class_name, probe);
480 throw_circularity_error = true;
481 }
482
483 // Make sure there's a placeholder for the class_name before resolving.
484 // This is used as a claim that this thread is currently loading superclass/classloader
485 // and for ClassCircularity checks.
486 if (!throw_circularity_error) {
487 // Be careful not to exit resolve_with_circularity_detection without removing this placeholder.
488 PlaceholderEntry* newprobe = PlaceholderTable::find_and_add(class_name,
489 loader_data,
490 PlaceholderTable::DETECT_CIRCULARITY,
491 next_name, THREAD);
492 }
493 }
494
495 if (throw_circularity_error) {
496 ResourceMark rm(THREAD);
497 THROW_MSG_NULL(vmSymbols::java_lang_ClassCircularityError(), class_name->as_C_string());
498 }
499
500 // Resolve the superclass or superinterface, check results on return
501 InstanceKlass* superk =
502 SystemDictionary::resolve_instance_class_or_null(next_name,
503 class_loader,
504 THREAD);
505
506 // Clean up placeholder entry.
507 {
508 MutexLocker mu(THREAD, SystemDictionary_lock);
509 PlaceholderTable::find_and_remove(class_name, loader_data, PlaceholderTable::DETECT_CIRCULARITY, THREAD);
510 SystemDictionary_lock->notify_all();
511 }
512
513 // Check for pending exception or null superk, and throw exception
514 if (HAS_PENDING_EXCEPTION || superk == nullptr) {
515 handle_resolution_exception(next_name, true, CHECK_NULL);
516 }
517
518 return superk;
519 }
520
521 // If the class in is in the placeholder table, class loading is in progress.
522 // For cases where the application changes threads to load classes, it
523 // is critical to ClassCircularity detection that we try loading
524 // the superclass on the new thread internally, so we do parallel
525 // superclass loading here. This avoids deadlock for ClassCircularity
526 // detection for parallelCapable class loaders that lock on a per-class lock.
527 static void handle_parallel_super_load(Symbol* name,
528 Symbol* superclassname,
529 Handle class_loader,
530 TRAPS) {
531
532 // The result superk is not used; resolve_with_circularity_detection is called for circularity check only.
533 // This passes false to is_superclass to skip doing the unlikely optimization.
534 Klass* superk = SystemDictionary::resolve_with_circularity_detection(name,
535 superclassname,
536 class_loader,
537 false,
538 CHECK);
539 }
540
541 // Bootstrap and non-parallel capable class loaders use the LOAD_INSTANCE placeholder to
542 // wait for parallel class loading and/or to check for circularity error for Xcomp when loading.
543 static bool needs_load_placeholder(Handle class_loader) {
544 return class_loader.is_null() || !is_parallelCapable(class_loader);
545 }
546
547 // Check for other threads loading this class either to throw CCE or wait in the case of the boot loader.
548 static InstanceKlass* handle_parallel_loading(JavaThread* current,
549 Symbol* name,
550 ClassLoaderData* loader_data,
551 bool must_wait_for_class_loading,
552 bool* throw_circularity_error) {
553 PlaceholderEntry* oldprobe = PlaceholderTable::get_entry(name, loader_data);
554 if (oldprobe != nullptr) {
555 // -Xcomp calls load_signature_classes which might result in loading
556 // a class that's already in the process of loading, so we detect CCE here also.
557 // Only need check_seen_thread once, not on each loop
558 if (oldprobe->check_seen_thread(current, PlaceholderTable::LOAD_INSTANCE)) {
559 log_circularity_error(name, oldprobe);
560 *throw_circularity_error = true;
561 return nullptr;
562 } else if (must_wait_for_class_loading) {
563 // Wait until the first thread has finished loading this class. Also wait until all the
564 // threads trying to load its superclass have removed their placeholders.
565 while (oldprobe != nullptr &&
566 (oldprobe->instance_load_in_progress() || oldprobe->circularity_detection_in_progress())) {
567
568 // LOAD_INSTANCE placeholders are used to implement parallel capable class loading
569 // for the bootclass loader.
570 SystemDictionary_lock->wait();
571
572 // Check if classloading completed while we were waiting
573 InstanceKlass* check = loader_data->dictionary()->find_class(current, name);
574 if (check != nullptr) {
575 // Klass is already loaded, so just return it
576 return check;
577 }
578 // check if other thread failed to load and cleaned up
579 oldprobe = PlaceholderTable::get_entry(name, loader_data);
580 }
581 }
582 }
583 return nullptr;
584 }
585
586 void SystemDictionary::post_class_load_event(EventClassLoad* event, const InstanceKlass* k, const ClassLoaderData* init_cld) {
587 assert(event != nullptr, "invariant");
588 assert(k != nullptr, "invariant");
589 event->set_loadedClass(k);
590 event->set_definingClassLoader(k->class_loader_data());
591 event->set_initiatingClassLoader(init_cld);
592 event->commit();
593 }
594
595 // SystemDictionary::resolve_instance_class_or_null is the main function for class name resolution.
596 // After checking if the InstanceKlass already exists, it checks for ClassCircularityError and
597 // whether the thread must wait for loading in parallel. It eventually calls load_instance_class,
598 // which will load the class via the bootstrap loader or call ClassLoader.loadClass().
599 // This can return null, an exception or an InstanceKlass.
600 InstanceKlass* SystemDictionary::resolve_instance_class_or_null(Symbol* name,
601 Handle class_loader,
602 TRAPS) {
603 // name must be in the form of "java/lang/Object" -- cannot be "Ljava/lang/Object;"
604 DEBUG_ONLY(ResourceMark rm(THREAD));
605 assert(name != nullptr && !Signature::is_array(name) &&
606 !Signature::has_envelope(name), "invalid class name: %s", name == nullptr ? "nullptr" : name->as_C_string());
607
608 EventClassLoad class_load_start_event;
609
610 HandleMark hm(THREAD);
611
612 ClassLoaderData* loader_data = register_loader(class_loader);
613 Dictionary* dictionary = loader_data->dictionary();
614
615 // Do lookup to see if class already exists.
616 InstanceKlass* probe = dictionary->find_class(THREAD, name);
617 if (probe != nullptr) return probe;
618
619 // Non-bootstrap class loaders will call out to class loader and
620 // define via jvm/jni_DefineClass which will acquire the
621 // class loader object lock to protect against multiple threads
622 // defining the class in parallel by accident.
623 // This lock must be acquired here so the waiter will find
624 // any successful result in the SystemDictionary and not attempt
625 // the define.
626 // ParallelCapable class loaders and the bootstrap classloader
627 // do not acquire lock here.
628 Handle lockObject = get_loader_lock_or_null(class_loader);
629 ObjectLocker ol(lockObject, THREAD);
630
631 bool circularity_detection_in_progress = false;
632 InstanceKlass* loaded_class = nullptr;
633 SymbolHandle superclassname; // Keep alive while loading in parallel thread.
634
635 guarantee(THREAD->can_call_java(),
636 "can not load classes with compiler thread: class=%s, classloader=%s",
637 name->as_C_string(),
638 class_loader.is_null() ? "null" : class_loader->klass()->name()->as_C_string());
639
640 // Check again (after locking) if the class already exists in SystemDictionary
641 {
642 MutexLocker mu(THREAD, SystemDictionary_lock);
643 InstanceKlass* check = dictionary->find_class(THREAD, name);
644 if (check != nullptr) {
645 // InstanceKlass is already loaded, but we still need to check protection domain below.
646 loaded_class = check;
647 } else {
648 PlaceholderEntry* placeholder = PlaceholderTable::get_entry(name, loader_data);
649 if (placeholder != nullptr && placeholder->circularity_detection_in_progress()) {
650 circularity_detection_in_progress = true;
651 superclassname = placeholder->next_klass_name();
652 assert(superclassname != nullptr, "superclass has to have a name");
653 }
654 }
655 }
656
657 // If the class is in the placeholder table with super_class set,
658 // handle superclass loading in progress.
659 if (circularity_detection_in_progress) {
660 handle_parallel_super_load(name, superclassname,
661 class_loader,
662 CHECK_NULL);
663 }
664
665 bool throw_circularity_error = false;
666 if (loaded_class == nullptr) {
667 bool load_placeholder_added = false;
668
669 // Add placeholder entry to record loading instance class
670 // case 1. Bootstrap classloader
671 // This classloader supports parallelism at the classloader level
672 // but only allows a single thread to load a class/classloader pair.
673 // The LOAD_INSTANCE placeholder is the mechanism for mutual exclusion.
674 // case 2. parallelCapable user level classloaders
675 // These class loaders lock a per-class object lock when ClassLoader.loadClass()
676 // is called. A LOAD_INSTANCE placeholder isn't used for mutual exclusion.
677 // case 3. traditional classloaders that rely on the classloader object lock
678 // There should be no need for need for LOAD_INSTANCE for mutual exclusion,
679 // except the LOAD_INSTANCE placeholder is used to detect CCE for -Xcomp.
680 // TODO: should also be used to detect CCE for parallel capable class loaders but it's not.
681 {
682 MutexLocker mu(THREAD, SystemDictionary_lock);
683 if (needs_load_placeholder(class_loader)) {
684 loaded_class = handle_parallel_loading(THREAD,
685 name,
686 loader_data,
687 class_loader.is_null(),
688 &throw_circularity_error);
689 }
690
691 // Recheck if the class has been loaded for all class loader cases and
692 // add a LOAD_INSTANCE placeholder while holding the SystemDictionary_lock.
693 if (!throw_circularity_error && loaded_class == nullptr) {
694 InstanceKlass* check = dictionary->find_class(THREAD, name);
695 if (check != nullptr) {
696 loaded_class = check;
697 } else if (needs_load_placeholder(class_loader)) {
698 // Add the LOAD_INSTANCE token. Threads will wait on loading to complete for this thread.
699 PlaceholderEntry* newprobe = PlaceholderTable::find_and_add(name, loader_data,
700 PlaceholderTable::LOAD_INSTANCE,
701 nullptr,
702 THREAD);
703 load_placeholder_added = true;
704 }
705 }
706 }
707
708 // Must throw error outside of owning lock
709 if (throw_circularity_error) {
710 assert(!HAS_PENDING_EXCEPTION && !load_placeholder_added, "circularity error cleanup");
711 ResourceMark rm(THREAD);
712 THROW_MSG_NULL(vmSymbols::java_lang_ClassCircularityError(), name->as_C_string());
713 }
714
715 // Be careful when modifying this code: once you have run
716 // PlaceholderTable::find_and_add(PlaceholderTable::LOAD_INSTANCE),
717 // you need to find_and_remove it before returning.
718 // So be careful to not exit with a CHECK_ macro between these calls.
719
720 if (loaded_class == nullptr) {
721 // Do actual loading
722 loaded_class = load_instance_class(name, class_loader, THREAD);
723 }
724
725 if (load_placeholder_added) {
726 // clean up placeholder entries for LOAD_INSTANCE success or error
727 // This brackets the SystemDictionary updates for both defining
728 // and initiating loaders
729 MutexLocker mu(THREAD, SystemDictionary_lock);
730 PlaceholderTable::find_and_remove(name, loader_data, PlaceholderTable::LOAD_INSTANCE, THREAD);
731 SystemDictionary_lock->notify_all();
732 }
733 }
734
735 if (HAS_PENDING_EXCEPTION || loaded_class == nullptr) {
736 return nullptr;
737 }
738
739 if (class_load_start_event.should_commit()) {
740 post_class_load_event(&class_load_start_event, loaded_class, loader_data);
741 }
742
743 // Make sure we have the right class in the dictionary
744 DEBUG_ONLY(verify_dictionary_entry(name, loaded_class));
745
746 return loaded_class;
747 }
748
749
750 // This routine does not lock the system dictionary.
751 //
752 // Since readers don't hold a lock, we must make sure that system
753 // dictionary entries are added to in a safe way (all links must
754 // be updated in an MT-safe manner). All entries are removed during class
755 // unloading, when this class loader is no longer referenced.
756 //
757 // Callers should be aware that an entry could be added just after
758 // Dictionary is read here, so the caller will not see
759 // the new entry.
760
761 InstanceKlass* SystemDictionary::find_instance_klass(Thread* current,
762 Symbol* class_name,
763 Handle class_loader) {
764
765 ClassLoaderData* loader_data = ClassLoaderData::class_loader_data_or_null(class_loader());
766 if (loader_data == nullptr) {
767 // If the ClassLoaderData has not been setup,
768 // then the class loader has no entries in the dictionary.
769 return nullptr;
770 }
771
772 Dictionary* dictionary = loader_data->dictionary();
773 return dictionary->find_class(current, class_name);
774 }
775
776 // Look for a loaded instance or array klass by name. Do not do any loading.
777 // return null in case of error.
778 Klass* SystemDictionary::find_instance_or_array_klass(Thread* current,
779 Symbol* class_name,
780 Handle class_loader) {
781 Klass* k = nullptr;
782 assert(class_name != nullptr, "class name must be non nullptr");
783
784 if (Signature::is_array(class_name)) {
785 // The name refers to an array. Parse the name.
786 // dimension and object_key in FieldArrayInfo are assigned as a
787 // side-effect of this call
788 SignatureStream ss(class_name, false);
789 int ndims = ss.skip_array_prefix(); // skip all '['s
790 BasicType t = ss.type();
791 if (t != T_OBJECT) {
792 k = Universe::typeArrayKlass(t);
793 } else {
794 k = SystemDictionary::find_instance_klass(current, ss.as_symbol(), class_loader);
795 }
796 if (k != nullptr) {
797 k = k->array_klass_or_null(ndims);
798 }
799 } else {
800 k = find_instance_klass(current, class_name, class_loader);
801 }
802 return k;
803 }
804
805 // Note: this method is much like resolve_class_from_stream, but
806 // does not publish the classes in the SystemDictionary.
807 // Handles Lookup.defineClass hidden.
808 InstanceKlass* SystemDictionary::resolve_hidden_class_from_stream(
809 ClassFileStream* st,
810 Symbol* class_name,
811 Handle class_loader,
812 const ClassLoadInfo& cl_info,
813 TRAPS) {
814
815 EventClassLoad class_load_start_event;
816 ClassLoaderData* loader_data;
817
818 // - for hidden classes that are not strong: create a new CLD that has a class holder and
819 // whose loader is the Lookup class's loader.
820 // - for hidden class: add the class to the Lookup class's loader's CLD.
821 assert (cl_info.is_hidden(), "only used for hidden classes");
822 bool create_mirror_cld = !cl_info.is_strong_hidden();
823 loader_data = register_loader(class_loader, create_mirror_cld);
824
825 assert(st != nullptr, "invariant");
826
827 // Parse stream and create a klass.
828 InstanceKlass* k = KlassFactory::create_from_stream(st,
829 class_name,
830 loader_data,
831 cl_info,
832 CHECK_NULL);
833 assert(k != nullptr, "no klass created");
834
835 // Hidden classes that are not strong must update ClassLoaderData holder
836 // so that they can be unloaded when the mirror is no longer referenced.
837 if (!cl_info.is_strong_hidden()) {
838 k->class_loader_data()->initialize_holder(Handle(THREAD, k->java_mirror()));
839 }
840
841 // Add to class hierarchy, and do possible deoptimizations.
842 k->add_to_hierarchy(THREAD);
843 // But, do not add to dictionary.
844
845 k->link_class(CHECK_NULL);
846
847 // notify jvmti
848 if (JvmtiExport::should_post_class_load()) {
849 JvmtiExport::post_class_load(THREAD, k);
850 }
851 if (class_load_start_event.should_commit()) {
852 post_class_load_event(&class_load_start_event, k, loader_data);
853 }
854
855 return k;
856 }
857
858 // Add a klass to the system from a stream (called by jni_DefineClass and
859 // JVM_DefineClass).
860 // Note: class_name can be null. In that case we do not know the name of
861 // the class until we have parsed the stream.
862 // This function either returns an InstanceKlass or throws an exception. It does
863 // not return null without a pending exception.
864 InstanceKlass* SystemDictionary::resolve_class_from_stream(
865 ClassFileStream* st,
866 Symbol* class_name,
867 Handle class_loader,
868 const ClassLoadInfo& cl_info,
869 TRAPS) {
870
871 HandleMark hm(THREAD);
872
873 ClassLoaderData* loader_data = register_loader(class_loader);
874
875 // Classloaders that support parallelism, e.g. bootstrap classloader,
876 // do not acquire lock here
877 Handle lockObject = get_loader_lock_or_null(class_loader);
878 ObjectLocker ol(lockObject, THREAD);
879
880 // Parse the stream and create a klass.
881 // Note that we do this even though this klass might
882 // already be present in the SystemDictionary, otherwise we would not
883 // throw potential ClassFormatErrors.
884 InstanceKlass* k = nullptr;
885
886 #if INCLUDE_CDS
887 if (!CDSConfig::is_dumping_static_archive()) {
888 k = SystemDictionaryShared::lookup_from_stream(class_name,
889 class_loader,
890 cl_info.protection_domain(),
891 st,
892 CHECK_NULL);
893 }
894 #endif
895
896 if (k == nullptr) {
897 k = KlassFactory::create_from_stream(st, class_name, loader_data, cl_info, CHECK_NULL);
898 }
899
900 assert(k != nullptr, "no klass created");
901 Symbol* h_name = k->name();
902 assert(class_name == nullptr || class_name == h_name, "name mismatch");
903
904 // Add class just loaded
905 // If a class loader supports parallel classloading, handle parallel define requests.
906 // find_or_define_instance_class may return a different InstanceKlass,
907 // in which case the old k would be deallocated
908 if (is_parallelCapable(class_loader)) {
909 k = find_or_define_instance_class(h_name, class_loader, k, CHECK_NULL);
910 } else {
911 define_instance_class(k, class_loader, THREAD);
912
913 // If defining the class throws an exception register 'k' for cleanup.
914 if (HAS_PENDING_EXCEPTION) {
915 assert(k != nullptr, "Must have an instance klass here!");
916 loader_data->add_to_deallocate_list(k);
917 return nullptr;
918 }
919 }
920
921 // Make sure we have an entry in the SystemDictionary on success
922 DEBUG_ONLY(verify_dictionary_entry(h_name, k));
923
924 return k;
925 }
926
927 InstanceKlass* SystemDictionary::resolve_from_stream(ClassFileStream* st,
928 Symbol* class_name,
929 Handle class_loader,
930 const ClassLoadInfo& cl_info,
931 TRAPS) {
932 if (cl_info.is_hidden()) {
933 return resolve_hidden_class_from_stream(st, class_name, class_loader, cl_info, CHECK_NULL);
934 } else {
935 return resolve_class_from_stream(st, class_name, class_loader, cl_info, CHECK_NULL);
936 }
937 }
938
939
940 #if INCLUDE_CDS
941 // Check if a shared class can be loaded by the specific classloader.
942 bool SystemDictionary::is_shared_class_visible(Symbol* class_name,
943 InstanceKlass* ik,
944 PackageEntry* pkg_entry,
945 Handle class_loader) {
946 assert(!CDSConfig::module_patching_disables_cds(), "Cannot use CDS");
947
948 // (1) Check if we are loading into the same loader as in dump time.
949
950 if (ik->defined_by_boot_loader()) {
951 if (class_loader() != nullptr) {
952 return false;
953 }
954 } else if (ik->defined_by_platform_loader()) {
955 if (class_loader() != java_platform_loader()) {
956 return false;
957 }
958 } else if (ik->defined_by_app_loader()) {
959 if (class_loader() != java_system_loader()) {
960 return false;
961 }
962 } else {
963 // ik was loaded by a custom loader during dump time
964 if (class_loader_data(class_loader)->is_builtin_class_loader_data()) {
965 return false;
966 } else {
967 return true;
968 }
969 }
970
971 // (2) Check if we are loading into the same module from the same location as in dump time.
972
973 if (CDSConfig::is_using_optimized_module_handling()) {
974 // Class visibility has not changed between dump time and run time, so a class
975 // that was visible (and thus archived) during dump time is always visible during runtime.
976 assert(SystemDictionary::is_shared_class_visible_impl(class_name, ik, pkg_entry, class_loader),
977 "visibility cannot change between dump time and runtime");
978 return true;
979 }
980 return is_shared_class_visible_impl(class_name, ik, pkg_entry, class_loader);
981 }
982
983 bool SystemDictionary::is_shared_class_visible_impl(Symbol* class_name,
984 InstanceKlass* ik,
985 PackageEntry* pkg_entry,
986 Handle class_loader) {
987 int scp_index = ik->shared_classpath_index();
988 assert(!ik->defined_by_other_loaders(), "this function should be called for built-in classes only");
989 assert(scp_index >= 0, "must be");
990 const AOTClassLocation* cl = AOTClassLocationConfig::runtime()->class_location_at(scp_index);
991 if (!Universe::is_module_initialized()) {
992 assert(cl != nullptr, "must be");
993 // At this point, no modules have been defined yet. KlassSubGraphInfo::check_allowed_klass()
994 // has restricted the classes can be loaded at this step to be only:
995 // [1] cs->is_modules_image(): classes in java.base, or,
996 // [2] HeapShared::is_a_test_class_in_unnamed_module(ik): classes in bootstrap/unnamed module
997 assert(cl->is_modules_image() || HeapShared::is_a_test_class_in_unnamed_module(ik),
998 "only these classes can be loaded before the module system is initialized");
999 assert(class_loader.is_null(), "sanity");
1000 return true;
1001 }
1002
1003 if (pkg_entry == nullptr) {
1004 // We might have looked up pkg_entry before the module system was initialized.
1005 // Need to reload it now.
1006 TempNewSymbol pkg_name = ClassLoader::package_from_class_name(class_name);
1007 if (pkg_name != nullptr) {
1008 pkg_entry = class_loader_data(class_loader)->packages()->lookup_only(pkg_name);
1009 }
1010 }
1011
1012 ModuleEntry* mod_entry = (pkg_entry == nullptr) ? nullptr : pkg_entry->module();
1013 bool should_be_in_named_module = (mod_entry != nullptr && mod_entry->is_named());
1014 bool was_archived_from_named_module = !cl->has_unnamed_module();
1015 bool visible;
1016
1017 if (was_archived_from_named_module) {
1018 if (should_be_in_named_module) {
1019 // Is the module loaded from the same location as during dump time?
1020 visible = mod_entry->shared_path_index() == scp_index;
1021 if (visible) {
1022 assert(!CDSConfig::module_patching_disables_cds(), "Cannot use CDS");
1023 }
1024 } else {
1025 // During dump time, this class was in a named module, but at run time, this class should be
1026 // in an unnamed module.
1027 visible = false;
1028 }
1029 } else {
1030 if (should_be_in_named_module) {
1031 // During dump time, this class was in an unnamed, but at run time, this class should be
1032 // in a named module.
1033 visible = false;
1034 } else {
1035 visible = true;
1036 }
1037 }
1038
1039 return visible;
1040 }
1041
1042 bool SystemDictionary::check_shared_class_super_type(InstanceKlass* klass, InstanceKlass* super_type,
1043 Handle class_loader, bool is_superclass, TRAPS) {
1044 assert(super_type->is_shared(), "must be");
1045
1046 // Quick check if the super type has been already loaded.
1047 // + Don't do it for unregistered classes -- they can be unloaded so
1048 // super_type->class_loader_data() could be stale.
1049 // + Don't check if loader data is null, ie. the super_type isn't fully loaded.
1050 if (!super_type->defined_by_other_loaders() && super_type->class_loader_data() != nullptr) {
1051 // Check if the superclass is loaded by the current class_loader
1052 Symbol* name = super_type->name();
1053 InstanceKlass* check = find_instance_klass(THREAD, name, class_loader);
1054 if (check == super_type) {
1055 return true;
1056 }
1057 }
1058
1059 Klass *found = resolve_with_circularity_detection(klass->name(), super_type->name(),
1060 class_loader, is_superclass, CHECK_false);
1061 if (found == super_type) {
1062 return true;
1063 } else {
1064 // The dynamically resolved super type is not the same as the one we used during dump time,
1065 // so we cannot use the class.
1066 return false;
1067 }
1068 }
1069
1070 bool SystemDictionary::check_shared_class_super_types(InstanceKlass* ik, Handle class_loader, TRAPS) {
1071 // Check the superclass and interfaces. They must be the same
1072 // as in dump time, because the layout of <ik> depends on
1073 // the specific layout of ik->super() and ik->local_interfaces().
1074 //
1075 // If unexpected superclass or interfaces are found, we cannot
1076 // load <ik> from the shared archive.
1077
1078 if (ik->super() != nullptr) {
1079 bool check_super = check_shared_class_super_type(ik, InstanceKlass::cast(ik->super()),
1080 class_loader, true,
1081 CHECK_false);
1082 if (!check_super) {
1083 return false;
1084 }
1085 }
1086
1087 Array<InstanceKlass*>* interfaces = ik->local_interfaces();
1088 int num_interfaces = interfaces->length();
1089 for (int index = 0; index < num_interfaces; index++) {
1090 bool check_interface = check_shared_class_super_type(ik, interfaces->at(index), class_loader, false,
1091 CHECK_false);
1092 if (!check_interface) {
1093 return false;
1094 }
1095 }
1096
1097 return true;
1098 }
1099
1100 // Pre-load class referred to in non-static null-free instance field. These fields trigger MANDATORY loading.
1101 // Some pre-loading does not fail fatally
1102 bool SystemDictionary::preload_from_null_free_field(InstanceKlass* ik, Handle class_loader, Symbol* sig, int field_index, TRAPS) {
1103 TempNewSymbol name = Signature::strip_envelope(sig);
1104 log_info(class, preload)("Preloading class %s during loading of shared class %s. "
1105 "Cause: a null-free non-static field is declared with this type",
1106 name->as_C_string(), ik->name()->as_C_string());
1107 InstanceKlass* real_k = SystemDictionary::resolve_with_circularity_detection_or_fail(ik->name(), name,
1108 class_loader, false, CHECK_false);
1109 if (HAS_PENDING_EXCEPTION) {
1110 log_warning(class, preload)("Preloading of class %s during loading of class %s "
1111 "(cause: null-free non-static field) failed: %s",
1112 name->as_C_string(), ik->name()->as_C_string(),
1113 PENDING_EXCEPTION->klass()->name()->as_C_string());
1114 return false; // Exception is still pending
1115 }
1116
1117 InstanceKlass* k = ik->get_inline_type_field_klass_or_null(field_index);
1118 if (real_k != k) {
1119 // oops, the app has substituted a different version of k! Does not fail fatally
1120 log_warning(class, preload)("Preloading of class %s during loading of shared class %s "
1121 "(cause: null-free non-static field) failed : "
1122 "app substituted a different version of %s",
1123 name->as_C_string(), ik->name()->as_C_string(),
1124 name->as_C_string());
1125 return false;
1126 }
1127 log_info(class, preload)("Preloading of class %s during loading of shared class %s "
1128 "(cause: null-free non-static field) succeeded",
1129 name->as_C_string(), ik->name()->as_C_string());
1130
1131 assert(real_k != nullptr, "Sanity check");
1132 InstanceKlass::check_can_be_annotated_with_NullRestricted(real_k, ik->name(), CHECK_false);
1133
1134 return true;
1135 }
1136
1137 // Tries to pre-load classes referred to in non-static nullable instance fields if they are found in the
1138 // loadable descriptors attribute. If loading fails, we can fail silently.
1139 void SystemDictionary::try_preload_from_loadable_descriptors(InstanceKlass* ik, Handle class_loader, Symbol* sig, int field_index, TRAPS) {
1140 TempNewSymbol name = Signature::strip_envelope(sig);
1141 if (name != ik->name() && ik->is_class_in_loadable_descriptors_attribute(sig)) {
1142 log_info(class, preload)("Preloading class %s during loading of shared class %s. "
1143 "Cause: field type in LoadableDescriptors attribute",
1144 name->as_C_string(), ik->name()->as_C_string());
1145 InstanceKlass* real_k = SystemDictionary::resolve_with_circularity_detection_or_fail(ik->name(), name,
1146 class_loader, false, THREAD);
1147 if (HAS_PENDING_EXCEPTION) {
1148 CLEAR_PENDING_EXCEPTION;
1149 }
1150
1151 InstanceKlass* k = ik->get_inline_type_field_klass_or_null(field_index);
1152 if (real_k != k) {
1153 // oops, the app has substituted a different version of k!
1154 log_warning(class, preload)("Preloading of class %s during loading of shared class %s "
1155 "(cause: field type in LoadableDescriptors attribute) failed : "
1156 "app substituted a different version of %s",
1157 name->as_C_string(), ik->name()->as_C_string(),
1158 k->name()->as_C_string());
1159 return;
1160 } else if (real_k != nullptr) {
1161 log_info(class, preload)("Preloading of class %s during loading of shared class %s "
1162 "(cause: field type in LoadableDescriptors attribute) succeeded",
1163 name->as_C_string(), ik->name()->as_C_string());
1164 }
1165 }
1166 }
1167
1168
1169 InstanceKlass* SystemDictionary::load_shared_class(InstanceKlass* ik,
1170 Handle class_loader,
1171 Handle protection_domain,
1172 const ClassFileStream *cfs,
1173 PackageEntry* pkg_entry,
1174 TRAPS) {
1175 assert(ik != nullptr, "sanity");
1176 assert(ik->is_shared(), "sanity");
1177 assert(!ik->is_unshareable_info_restored(), "shared class can be restored only once");
1178 assert(Atomic::add(&ik->_shared_class_load_count, 1) == 1, "shared class loaded more than once");
1179 Symbol* class_name = ik->name();
1180
1181 if (!is_shared_class_visible(class_name, ik, pkg_entry, class_loader)) {
1182 ik->set_shared_loading_failed();
1183 return nullptr;
1184 }
1185
1186 bool check = check_shared_class_super_types(ik, class_loader, CHECK_NULL);
1187 if (!check) {
1188 ik->set_shared_loading_failed();
1189 return nullptr;
1190 }
1191
1192 if (ik->has_inline_type_fields()) {
1193 for (AllFieldStream fs(ik); !fs.done(); fs.next()) {
1194 if (fs.access_flags().is_static()) continue;
1195
1196 Symbol* sig = fs.signature();
1197 int field_index = fs.index();
1198
1199 if (fs.is_null_free_inline_type()) {
1200 // A false return means that the class didn't load for other reasons than an exception.
1201 bool check = preload_from_null_free_field(ik, class_loader, sig, field_index, CHECK_NULL);
1202 if (!check) {
1203 ik->set_shared_loading_failed();
1204 return nullptr;
1205 }
1206 } else if (Signature::has_envelope(sig)) {
1207 // Pending exceptions are cleared so we can fail silently
1208 try_preload_from_loadable_descriptors(ik, class_loader, sig, field_index, CHECK_NULL);
1209 }
1210 }
1211 }
1212
1213 InstanceKlass* new_ik = nullptr;
1214 // CFLH check is skipped for VM hidden classes (see KlassFactory::create_from_stream).
1215 // It will be skipped for shared VM hidden lambda proxy classes.
1216 if (!ik->is_hidden()) {
1217 new_ik = KlassFactory::check_shared_class_file_load_hook(
1218 ik, class_name, class_loader, protection_domain, cfs, CHECK_NULL);
1219 }
1220 if (new_ik != nullptr) {
1221 // The class is changed by CFLH. Return the new class. The shared class is
1222 // not used.
1223 return new_ik;
1224 }
1225
1226 // Adjust methods to recover missing data. They need addresses for
1227 // interpreter entry points and their default native method address
1228 // must be reset.
1229
1230 // Shared classes are all currently loaded by either the bootstrap or
1231 // internal parallel class loaders, so this will never cause a deadlock
1232 // on a custom class loader lock.
1233 // Since this class is already locked with parallel capable class
1234 // loaders, including the bootstrap loader via the placeholder table,
1235 // this lock is currently a nop.
1236
1237 ClassLoaderData* loader_data = class_loader_data(class_loader);
1238 {
1239 HandleMark hm(THREAD);
1240 Handle lockObject = get_loader_lock_or_null(class_loader);
1241 ObjectLocker ol(lockObject, THREAD);
1242 // prohibited package check assumes all classes loaded from archive call
1243 // restore_unshareable_info which calls ik->set_package()
1244 ik->restore_unshareable_info(loader_data, protection_domain, pkg_entry, CHECK_NULL);
1245 }
1246
1247 load_shared_class_misc(ik, loader_data);
1248
1249 return ik;
1250 }
1251
1252 void SystemDictionary::load_shared_class_misc(InstanceKlass* ik, ClassLoaderData* loader_data) {
1253 ik->print_class_load_logging(loader_data, nullptr, nullptr);
1254
1255 // For boot loader, ensure that GetSystemPackage knows that a class in this
1256 // package was loaded.
1257 if (loader_data->is_the_null_class_loader_data()) {
1258 s2 path_index = ik->shared_classpath_index();
1259 ik->set_classpath_index(path_index);
1260 }
1261
1262 // notify a class loaded from shared object
1263 ClassLoadingService::notify_class_loaded(ik, true /* shared class */);
1264
1265 if (CDSConfig::is_dumping_final_static_archive()) {
1266 SystemDictionaryShared::init_dumptime_info_from_preimage(ik);
1267 }
1268 }
1269
1270 #endif // INCLUDE_CDS
1271
1272 InstanceKlass* SystemDictionary::load_instance_class_impl(Symbol* class_name, Handle class_loader, TRAPS) {
1273
1274 if (class_loader.is_null()) {
1275 ResourceMark rm(THREAD);
1276 PackageEntry* pkg_entry = nullptr;
1277 bool search_only_bootloader_append = false;
1278
1279 // Find the package in the boot loader's package entry table.
1280 TempNewSymbol pkg_name = ClassLoader::package_from_class_name(class_name);
1281 if (pkg_name != nullptr) {
1282 pkg_entry = class_loader_data(class_loader)->packages()->lookup_only(pkg_name);
1283 }
1284
1285 // Prior to attempting to load the class, enforce the boot loader's
1286 // visibility boundaries.
1287 if (!Universe::is_module_initialized()) {
1288 // During bootstrapping, prior to module initialization, any
1289 // class attempting to be loaded must be checked against the
1290 // java.base packages in the boot loader's PackageEntryTable.
1291 // No class outside of java.base is allowed to be loaded during
1292 // this bootstrapping window.
1293 if (pkg_entry == nullptr || pkg_entry->in_unnamed_module()) {
1294 // Class is either in the unnamed package or in
1295 // a named package within the unnamed module. Either
1296 // case is outside of java.base, do not attempt to
1297 // load the class post java.base definition. If
1298 // java.base has not been defined, let the class load
1299 // and its package will be checked later by
1300 // ModuleEntryTable::verify_javabase_packages.
1301 if (ModuleEntryTable::javabase_defined()) {
1302 return nullptr;
1303 }
1304 } else {
1305 // Check that the class' package is defined within java.base.
1306 ModuleEntry* mod_entry = pkg_entry->module();
1307 Symbol* mod_entry_name = mod_entry->name();
1308 if (mod_entry_name->fast_compare(vmSymbols::java_base()) != 0) {
1309 return nullptr;
1310 }
1311 }
1312 } else {
1313 // After the module system has been initialized, check if the class'
1314 // package is in a module defined to the boot loader.
1315 if (pkg_name == nullptr || pkg_entry == nullptr || pkg_entry->in_unnamed_module()) {
1316 // Class is either in the unnamed package, in a named package
1317 // within a module not defined to the boot loader or in a
1318 // a named package within the unnamed module. In all cases,
1319 // limit visibility to search for the class only in the boot
1320 // loader's append path.
1321 if (!ClassLoader::has_bootclasspath_append()) {
1322 // If there is no bootclasspath append entry, no need to continue
1323 // searching.
1324 return nullptr;
1325 }
1326 search_only_bootloader_append = true;
1327 }
1328 }
1329
1330 // Prior to bootstrapping's module initialization, never load a class outside
1331 // of the boot loader's module path
1332 assert(Universe::is_module_initialized() ||
1333 !search_only_bootloader_append,
1334 "Attempt to load a class outside of boot loader's module path");
1335
1336 // Search for classes in the CDS archive.
1337 InstanceKlass* k = nullptr;
1338
1339 #if INCLUDE_CDS
1340 if (CDSConfig::is_using_archive())
1341 {
1342 PerfTraceTime vmtimer(ClassLoader::perf_shared_classload_time());
1343 InstanceKlass* ik = SystemDictionaryShared::find_builtin_class(class_name);
1344 if (ik != nullptr && ik->defined_by_boot_loader() && !ik->shared_loading_failed()) {
1345 SharedClassLoadingMark slm(THREAD, ik);
1346 k = load_shared_class(ik, class_loader, Handle(), nullptr, pkg_entry, CHECK_NULL);
1347 }
1348 }
1349 #endif
1350
1351 if (k == nullptr) {
1352 // Use VM class loader
1353 PerfTraceTime vmtimer(ClassLoader::perf_sys_classload_time());
1354 k = ClassLoader::load_class(class_name, pkg_entry, search_only_bootloader_append, CHECK_NULL);
1355 }
1356
1357 // find_or_define_instance_class may return a different InstanceKlass
1358 if (k != nullptr) {
1359 CDS_ONLY(SharedClassLoadingMark slm(THREAD, k);)
1360 k = find_or_define_instance_class(class_name, class_loader, k, CHECK_NULL);
1361 }
1362 return k;
1363 } else {
1364 // Use user specified class loader to load class. Call loadClass operation on class_loader.
1365 ResourceMark rm(THREAD);
1366
1367 JavaThread* jt = THREAD;
1368
1369 PerfClassTraceTime vmtimer(ClassLoader::perf_app_classload_time(),
1370 ClassLoader::perf_app_classload_selftime(),
1371 ClassLoader::perf_app_classload_count(),
1372 jt->get_thread_stat()->perf_recursion_counts_addr(),
1373 jt->get_thread_stat()->perf_timers_addr(),
1374 PerfClassTraceTime::CLASS_LOAD);
1375
1376 // Translate to external class name format, i.e., convert '/' chars to '.'
1377 Handle string = java_lang_String::externalize_classname(class_name, CHECK_NULL);
1378
1379 JavaValue result(T_OBJECT);
1380
1381 InstanceKlass* spec_klass = vmClasses::ClassLoader_klass();
1382
1383 // Call public unsynchronized loadClass(String) directly for all class loaders.
1384 // For parallelCapable class loaders, JDK >=7, loadClass(String, boolean) will
1385 // acquire a class-name based lock rather than the class loader object lock.
1386 // JDK < 7 already acquire the class loader lock in loadClass(String, boolean).
1387 JavaCalls::call_virtual(&result,
1388 class_loader,
1389 spec_klass,
1390 vmSymbols::loadClass_name(),
1391 vmSymbols::string_class_signature(),
1392 string,
1393 CHECK_NULL);
1394
1395 assert(result.get_type() == T_OBJECT, "just checking");
1396 oop obj = result.get_oop();
1397
1398 // Primitive classes return null since forName() can not be
1399 // used to obtain any of the Class objects representing primitives or void
1400 if ((obj != nullptr) && !(java_lang_Class::is_primitive(obj))) {
1401 InstanceKlass* k = InstanceKlass::cast(java_lang_Class::as_Klass(obj));
1402 // For user defined Java class loaders, check that the name returned is
1403 // the same as that requested. This check is done for the bootstrap
1404 // loader when parsing the class file.
1405 if (class_name == k->name()) {
1406 return k;
1407 }
1408 }
1409 // Class is not found or has the wrong name, return null
1410 return nullptr;
1411 }
1412 }
1413
1414 InstanceKlass* SystemDictionary::load_instance_class(Symbol* name,
1415 Handle class_loader,
1416 TRAPS) {
1417
1418 InstanceKlass* loaded_class = load_instance_class_impl(name, class_loader, CHECK_NULL);
1419
1420 // If everything was OK (no exceptions, no null return value), and
1421 // class_loader is NOT the defining loader, do a little more bookkeeping.
1422 if (loaded_class != nullptr &&
1423 loaded_class->class_loader() != class_loader()) {
1424
1425 ClassLoaderData* loader_data = class_loader_data(class_loader);
1426 check_constraints(loaded_class, loader_data, false, CHECK_NULL);
1427
1428 // Record dependency for non-parent delegation.
1429 // This recording keeps the defining class loader of the klass (loaded_class) found
1430 // from being unloaded while the initiating class loader is loaded
1431 // even if the reference to the defining class loader is dropped
1432 // before references to the initiating class loader.
1433 loader_data->record_dependency(loaded_class);
1434
1435 update_dictionary(THREAD, loaded_class, loader_data);
1436
1437 if (JvmtiExport::should_post_class_load()) {
1438 JvmtiExport::post_class_load(THREAD, loaded_class);
1439 }
1440 }
1441 return loaded_class;
1442 }
1443
1444 static void post_class_define_event(InstanceKlass* k, const ClassLoaderData* def_cld) {
1445 EventClassDefine event;
1446 if (event.should_commit()) {
1447 event.set_definedClass(k);
1448 event.set_definingClassLoader(def_cld);
1449 event.commit();
1450 }
1451 }
1452
1453 void SystemDictionary::define_instance_class(InstanceKlass* k, Handle class_loader, TRAPS) {
1454
1455 ClassLoaderData* loader_data = k->class_loader_data();
1456 assert(loader_data->class_loader() == class_loader(), "they must be the same");
1457
1458 // Bootstrap and other parallel classloaders don't acquire a lock,
1459 // they use placeholder token.
1460 // If a parallelCapable class loader calls define_instance_class instead of
1461 // find_or_define_instance_class to get here, we have a timing
1462 // hole with systemDictionary updates and check_constraints
1463 if (!is_parallelCapable(class_loader)) {
1464 assert(ObjectSynchronizer::current_thread_holds_lock(THREAD,
1465 get_loader_lock_or_null(class_loader)),
1466 "define called without lock");
1467 }
1468
1469 // Check class-loading constraints. Throw exception if violation is detected.
1470 // Grabs and releases SystemDictionary_lock
1471 // The check_constraints/find_class call and update_dictionary sequence
1472 // must be "atomic" for a specific class/classloader pair so we never
1473 // define two different instanceKlasses for that class/classloader pair.
1474 // Existing classloaders will call define_instance_class with the
1475 // classloader lock held
1476 // Parallel classloaders will call find_or_define_instance_class
1477 // which will require a token to perform the define class
1478 check_constraints(k, loader_data, true, CHECK);
1479
1480 // Register class just loaded with class loader (placed in ArrayList)
1481 // Note we do this before updating the dictionary, as this can
1482 // fail with an OutOfMemoryError (if it does, we will *not* put this
1483 // class in the dictionary and will not update the class hierarchy).
1484 // JVMTI FollowReferences needs to find the classes this way.
1485 if (k->class_loader() != nullptr) {
1486 methodHandle m(THREAD, Universe::loader_addClass_method());
1487 JavaValue result(T_VOID);
1488 JavaCallArguments args(class_loader);
1489 args.push_oop(Handle(THREAD, k->java_mirror()));
1490 JavaCalls::call(&result, m, &args, CHECK);
1491 }
1492
1493 // Add to class hierarchy, and do possible deoptimizations.
1494 k->add_to_hierarchy(THREAD);
1495
1496 // Add to systemDictionary - so other classes can see it.
1497 // Grabs and releases SystemDictionary_lock
1498 update_dictionary(THREAD, k, loader_data);
1499
1500 // notify jvmti
1501 if (JvmtiExport::should_post_class_load()) {
1502 JvmtiExport::post_class_load(THREAD, k);
1503 }
1504 post_class_define_event(k, loader_data);
1505 }
1506
1507 // Support parallel classloading
1508 // All parallel class loaders, including bootstrap classloader
1509 // lock a placeholder entry for this class/class_loader pair
1510 // to allow parallel defines of different classes for this class loader
1511 // With AllowParallelDefine flag==true, in case they do not synchronize around
1512 // FindLoadedClass/DefineClass, calls, we check for parallel
1513 // loading for them, wait if a defineClass is in progress
1514 // and return the initial requestor's results
1515 // This flag does not apply to the bootstrap classloader.
1516 // With AllowParallelDefine flag==false, call through to define_instance_class
1517 // which will throw LinkageError: duplicate class definition.
1518 // False is the requested default.
1519 // For better performance, the class loaders should synchronize
1520 // findClass(), i.e. FindLoadedClass/DefineClassIfAbsent or they
1521 // potentially waste time reading and parsing the bytestream.
1522 // Note: VM callers should ensure consistency of k/class_name,class_loader
1523 // Be careful when modifying this code: once you have run
1524 // PlaceholderTable::find_and_add(PlaceholderTable::DEFINE_CLASS),
1525 // you need to find_and_remove it before returning.
1526 // So be careful to not exit with a CHECK_ macro between these calls.
1527 InstanceKlass* SystemDictionary::find_or_define_helper(Symbol* class_name, Handle class_loader,
1528 InstanceKlass* k, TRAPS) {
1529
1530 Symbol* name_h = k->name();
1531 ClassLoaderData* loader_data = class_loader_data(class_loader);
1532 Dictionary* dictionary = loader_data->dictionary();
1533
1534 // Hold SD lock around find_class and placeholder creation for DEFINE_CLASS
1535 {
1536 MutexLocker mu(THREAD, SystemDictionary_lock);
1537 // First check if class already defined
1538 if (is_parallelDefine(class_loader)) {
1539 InstanceKlass* check = dictionary->find_class(THREAD, name_h);
1540 if (check != nullptr) {
1541 return check;
1542 }
1543 }
1544
1545 // Acquire define token for this class/classloader
1546 PlaceholderEntry* probe = PlaceholderTable::find_and_add(name_h, loader_data,
1547 PlaceholderTable::DEFINE_CLASS, nullptr, THREAD);
1548 // Wait if another thread defining in parallel
1549 // All threads wait - even those that will throw duplicate class: otherwise
1550 // caller is surprised by LinkageError: duplicate, but findLoadedClass fails
1551 // if other thread has not finished updating dictionary
1552 while (probe->definer() != nullptr) {
1553 SystemDictionary_lock->wait();
1554 }
1555 // Only special cases allow parallel defines and can use other thread's results
1556 // Other cases fall through, and may run into duplicate defines
1557 // caught by finding an entry in the SystemDictionary
1558 if (is_parallelDefine(class_loader) && (probe->instance_klass() != nullptr)) {
1559 InstanceKlass* ik = probe->instance_klass();
1560 PlaceholderTable::find_and_remove(name_h, loader_data, PlaceholderTable::DEFINE_CLASS, THREAD);
1561 SystemDictionary_lock->notify_all();
1562 #ifdef ASSERT
1563 InstanceKlass* check = dictionary->find_class(THREAD, name_h);
1564 assert(check != nullptr, "definer missed recording success");
1565 #endif
1566 return ik;
1567 } else {
1568 // This thread will define the class (even if earlier thread tried and had an error)
1569 probe->set_definer(THREAD);
1570 }
1571 }
1572
1573 define_instance_class(k, class_loader, THREAD);
1574
1575 // definer must notify any waiting threads
1576 {
1577 MutexLocker mu(THREAD, SystemDictionary_lock);
1578 PlaceholderEntry* probe = PlaceholderTable::get_entry(name_h, loader_data);
1579 assert(probe != nullptr, "DEFINE_CLASS placeholder lost?");
1580 if (!HAS_PENDING_EXCEPTION) {
1581 probe->set_instance_klass(k);
1582 }
1583 probe->set_definer(nullptr);
1584 PlaceholderTable::find_and_remove(name_h, loader_data, PlaceholderTable::DEFINE_CLASS, THREAD);
1585 SystemDictionary_lock->notify_all();
1586 }
1587
1588 return HAS_PENDING_EXCEPTION ? nullptr : k;
1589 }
1590
1591 // If a class loader supports parallel classloading handle parallel define requests.
1592 // find_or_define_instance_class may return a different InstanceKlass
1593 InstanceKlass* SystemDictionary::find_or_define_instance_class(Symbol* class_name, Handle class_loader,
1594 InstanceKlass* k, TRAPS) {
1595 InstanceKlass* defined_k = find_or_define_helper(class_name, class_loader, k, THREAD);
1596 // Clean up original InstanceKlass if duplicate or error
1597 if (!HAS_PENDING_EXCEPTION && defined_k != k) {
1598 // If a parallel capable class loader already defined this class, register 'k' for cleanup.
1599 assert(defined_k != nullptr, "Should have a klass if there's no exception");
1600 k->class_loader_data()->add_to_deallocate_list(k);
1601 } else if (HAS_PENDING_EXCEPTION) {
1602 // Remove this InstanceKlass from the LoaderConstraintTable if added.
1603 LoaderConstraintTable::remove_failed_loaded_klass(k, class_loader_data(class_loader));
1604 assert(defined_k == nullptr, "Should not have a klass if there's an exception");
1605 k->class_loader_data()->add_to_deallocate_list(k);
1606 }
1607 return defined_k;
1608 }
1609
1610
1611 // ----------------------------------------------------------------------------
1612 // GC support
1613
1614 // Assumes classes in the SystemDictionary are only unloaded at a safepoint
1615 bool SystemDictionary::do_unloading(GCTimer* gc_timer) {
1616
1617 bool unloading_occurred;
1618 bool is_concurrent = !SafepointSynchronize::is_at_safepoint();
1619 {
1620 GCTraceTime(Debug, gc, phases) t("ClassLoaderData", gc_timer);
1621 assert_locked_or_safepoint(ClassLoaderDataGraph_lock); // caller locks.
1622 // First, mark for unload all ClassLoaderData referencing a dead class loader.
1623 unloading_occurred = ClassLoaderDataGraph::do_unloading();
1624 if (unloading_occurred) {
1625 ConditionalMutexLocker ml2(Module_lock, is_concurrent);
1626 JFR_ONLY(Jfr::on_unloading_classes();)
1627 MANAGEMENT_ONLY(FinalizerService::purge_unloaded();)
1628 ConditionalMutexLocker ml1(SystemDictionary_lock, is_concurrent);
1629 ClassLoaderDataGraph::clean_module_and_package_info();
1630 LoaderConstraintTable::purge_loader_constraints();
1631 ResolutionErrorTable::purge_resolution_errors();
1632 }
1633 }
1634
1635 GCTraceTime(Debug, gc, phases) t("Trigger cleanups", gc_timer);
1636
1637 if (unloading_occurred) {
1638 SymbolTable::trigger_cleanup();
1639
1640 ConditionalMutexLocker ml(ClassInitError_lock, is_concurrent);
1641 InstanceKlass::clean_initialization_error_table();
1642 }
1643
1644 return unloading_occurred;
1645 }
1646
1647 void SystemDictionary::methods_do(void f(Method*)) {
1648 // Walk methods in loaded classes
1649
1650 {
1651 MutexLocker ml(ClassLoaderDataGraph_lock);
1652 ClassLoaderDataGraph::methods_do(f);
1653 }
1654
1655 auto doit = [&] (InvokeMethodKey key, Method* method) {
1656 if (method != nullptr) {
1657 f(method);
1658 }
1659 };
1660
1661 {
1662 MutexLocker ml(InvokeMethodIntrinsicTable_lock);
1663 _invoke_method_intrinsic_table->iterate_all(doit);
1664 }
1665
1666 }
1667
1668 // ----------------------------------------------------------------------------
1669 // Initialization
1670
1671 void SystemDictionary::initialize(TRAPS) {
1672 _invoke_method_intrinsic_table = new (mtClass) InvokeMethodIntrinsicTable();
1673 _invoke_method_type_table = new (mtClass) InvokeMethodTypeTable();
1674 ResolutionErrorTable::initialize();
1675 LoaderConstraintTable::initialize();
1676 PlaceholderTable::initialize();
1677 #if INCLUDE_CDS
1678 SystemDictionaryShared::initialize();
1679 if (CDSConfig::is_dumping_archive()) {
1680 AOTClassLocationConfig::dumptime_init(THREAD);
1681 }
1682 #endif
1683 // Resolve basic classes
1684 vmClasses::resolve_all(CHECK);
1685 // Resolve classes used by archived heap objects
1686 if (CDSConfig::is_using_archive()) {
1687 HeapShared::resolve_classes(THREAD);
1688 }
1689 }
1690
1691 // Constraints on class loaders. The details of the algorithm can be
1692 // found in the OOPSLA'98 paper "Dynamic Class Loading in the Java
1693 // Virtual Machine" by Sheng Liang and Gilad Bracha. The basic idea is
1694 // that the dictionary needs to maintain a set of constraints that
1695 // must be satisfied by all classes in the dictionary.
1696 // if defining is true, then LinkageError if already in dictionary
1697 // if initiating loader, then ok if InstanceKlass matches existing entry
1698
1699 void SystemDictionary::check_constraints(InstanceKlass* k,
1700 ClassLoaderData* loader_data,
1701 bool defining,
1702 TRAPS) {
1703 ResourceMark rm(THREAD);
1704 stringStream ss;
1705 bool throwException = false;
1706
1707 {
1708 Symbol* name = k->name();
1709
1710 MutexLocker mu(THREAD, SystemDictionary_lock);
1711
1712 InstanceKlass* check = loader_data->dictionary()->find_class(THREAD, name);
1713 if (check != nullptr) {
1714 // If different InstanceKlass - duplicate class definition,
1715 // else - ok, class loaded by a different thread in parallel.
1716 // We should only have found it if it was done loading and ok to use.
1717
1718 if ((defining == true) || (k != check)) {
1719 throwException = true;
1720 ss.print("loader %s", loader_data->loader_name_and_id());
1721 ss.print(" attempted duplicate %s definition for %s. (%s)",
1722 k->external_kind(), k->external_name(), k->class_in_module_of_loader(false, true));
1723 } else {
1724 return;
1725 }
1726 }
1727
1728 if (throwException == false) {
1729 if (LoaderConstraintTable::check_or_update(k, loader_data, name) == false) {
1730 throwException = true;
1731 ss.print("loader constraint violation: loader %s", loader_data->loader_name_and_id());
1732 ss.print(" wants to load %s %s.",
1733 k->external_kind(), k->external_name());
1734 Klass *existing_klass = LoaderConstraintTable::find_constrained_klass(name, loader_data);
1735 if (existing_klass != nullptr && existing_klass->class_loader_data() != loader_data) {
1736 ss.print(" A different %s with the same name was previously loaded by %s. (%s)",
1737 existing_klass->external_kind(),
1738 existing_klass->class_loader_data()->loader_name_and_id(),
1739 existing_klass->class_in_module_of_loader(false, true));
1740 } else {
1741 ss.print(" (%s)", k->class_in_module_of_loader(false, true));
1742 }
1743 }
1744 }
1745 }
1746
1747 // Throw error now if needed (cannot throw while holding
1748 // SystemDictionary_lock because of rank ordering)
1749 if (throwException == true) {
1750 THROW_MSG(vmSymbols::java_lang_LinkageError(), ss.as_string());
1751 }
1752 }
1753
1754 // Update class loader data dictionary - done after check_constraint and add_to_hierarchy
1755 // have been called.
1756 void SystemDictionary::update_dictionary(JavaThread* current,
1757 InstanceKlass* k,
1758 ClassLoaderData* loader_data) {
1759 MonitorLocker mu1(SystemDictionary_lock);
1760
1761 // Make a new dictionary entry.
1762 Symbol* name = k->name();
1763 Dictionary* dictionary = loader_data->dictionary();
1764 InstanceKlass* sd_check = dictionary->find_class(current, name);
1765 if (sd_check == nullptr) {
1766 dictionary->add_klass(current, name, k);
1767 }
1768 mu1.notify_all();
1769 }
1770
1771 // Indicate that loader_data has initiated the loading of class k, which
1772 // has already been defined by a parent loader.
1773 // This API is used by AOTLinkedClassBulkLoader and to register boxing
1774 // classes from java.lang in all class loaders to enable more value
1775 // classes optimizations
1776 void SystemDictionary::add_to_initiating_loader(JavaThread* current,
1777 InstanceKlass* k,
1778 ClassLoaderData* loader_data) {
1779 assert_locked_or_safepoint(SystemDictionary_lock);
1780 Symbol* name = k->name();
1781 Dictionary* dictionary = loader_data->dictionary();
1782 assert(k->is_loaded(), "must be");
1783 assert(k->class_loader_data() != loader_data, "only for classes defined by a parent loader");
1784 if (dictionary->find_class(current, name) == nullptr) {
1785 dictionary->add_klass(current, name, k);
1786 }
1787 }
1788
1789 // Try to find a class name using the loader constraints. The
1790 // loader constraints might know about a class that isn't fully loaded
1791 // yet and these will be ignored.
1792 Klass* SystemDictionary::find_constrained_instance_or_array_klass(
1793 Thread* current, Symbol* class_name, Handle class_loader) {
1794
1795 // First see if it has been loaded directly.
1796 Klass* klass = find_instance_or_array_klass(current, class_name, class_loader);
1797 if (klass != nullptr)
1798 return klass;
1799
1800 // Now look to see if it has been loaded elsewhere, and is subject to
1801 // a loader constraint that would require this loader to return the
1802 // klass that is already loaded.
1803 if (Signature::is_array(class_name)) {
1804 // For array classes, their Klass*s are not kept in the
1805 // constraint table. The element Klass*s are.
1806 SignatureStream ss(class_name, false);
1807 int ndims = ss.skip_array_prefix(); // skip all '['s
1808 BasicType t = ss.type();
1809 if (t != T_OBJECT) {
1810 klass = Universe::typeArrayKlass(t);
1811 } else {
1812 MutexLocker mu(current, SystemDictionary_lock);
1813 klass = LoaderConstraintTable::find_constrained_klass(ss.as_symbol(), class_loader_data(class_loader));
1814 }
1815 // If element class already loaded, allocate array klass
1816 if (klass != nullptr) {
1817 klass = klass->array_klass_or_null(ndims);
1818 }
1819 } else {
1820 MutexLocker mu(current, SystemDictionary_lock);
1821 // Non-array classes are easy: simply check the constraint table.
1822 klass = LoaderConstraintTable::find_constrained_klass(class_name, class_loader_data(class_loader));
1823 }
1824
1825 return klass;
1826 }
1827
1828 bool SystemDictionary::add_loader_constraint(Symbol* class_name,
1829 Klass* klass_being_linked,
1830 Handle class_loader1,
1831 Handle class_loader2) {
1832 ClassLoaderData* loader_data1 = class_loader_data(class_loader1);
1833 ClassLoaderData* loader_data2 = class_loader_data(class_loader2);
1834
1835 Symbol* constraint_name = nullptr;
1836
1837 if (!Signature::is_array(class_name)) {
1838 constraint_name = class_name;
1839 } else {
1840 // For array classes, their Klass*s are not kept in the
1841 // constraint table. The element classes are.
1842 SignatureStream ss(class_name, false);
1843 ss.skip_array_prefix(); // skip all '['s
1844 if (!ss.has_envelope()) {
1845 return true; // primitive types always pass
1846 }
1847 constraint_name = ss.as_symbol();
1848 // Increment refcount to keep constraint_name alive after
1849 // SignatureStream is destructed. It will be decremented below
1850 // before returning.
1851 constraint_name->increment_refcount();
1852 }
1853
1854 Dictionary* dictionary1 = loader_data1->dictionary();
1855 Dictionary* dictionary2 = loader_data2->dictionary();
1856
1857 JavaThread* current = JavaThread::current();
1858 {
1859 MutexLocker mu_s(SystemDictionary_lock);
1860 InstanceKlass* klass1 = dictionary1->find_class(current, constraint_name);
1861 InstanceKlass* klass2 = dictionary2->find_class(current, constraint_name);
1862 bool result = LoaderConstraintTable::add_entry(constraint_name, klass1, loader_data1,
1863 klass2, loader_data2);
1864 #if INCLUDE_CDS
1865 if (CDSConfig::is_dumping_archive() && klass_being_linked != nullptr &&
1866 !klass_being_linked->is_shared()) {
1867 SystemDictionaryShared::record_linking_constraint(constraint_name,
1868 InstanceKlass::cast(klass_being_linked),
1869 class_loader1, class_loader2);
1870 }
1871 #endif // INCLUDE_CDS
1872 if (Signature::is_array(class_name)) {
1873 constraint_name->decrement_refcount();
1874 }
1875 return result;
1876 }
1877 }
1878
1879 // Add entry to resolution error table to record the error when the first
1880 // attempt to resolve a reference to a class has failed.
1881 void SystemDictionary::add_resolution_error(const constantPoolHandle& pool, int which,
1882 Symbol* error, const char* message,
1883 Symbol* cause, const char* cause_msg) {
1884 {
1885 MutexLocker ml(Thread::current(), SystemDictionary_lock);
1886 ResolutionErrorEntry* entry = ResolutionErrorTable::find_entry(pool, which);
1887 if (entry == nullptr) {
1888 ResolutionErrorTable::add_entry(pool, which, error, message, cause, cause_msg);
1889 }
1890 }
1891 }
1892
1893 // Delete a resolution error for RedefineClasses for a constant pool is going away
1894 void SystemDictionary::delete_resolution_error(ConstantPool* pool) {
1895 ResolutionErrorTable::delete_entry(pool);
1896 }
1897
1898 // Lookup resolution error table. Returns error if found, otherwise null.
1899 Symbol* SystemDictionary::find_resolution_error(const constantPoolHandle& pool, int which,
1900 const char** message,
1901 Symbol** cause, const char** cause_msg) {
1902
1903 {
1904 MutexLocker ml(Thread::current(), SystemDictionary_lock);
1905 ResolutionErrorEntry* entry = ResolutionErrorTable::find_entry(pool, which);
1906 if (entry != nullptr) {
1907 *message = entry->message();
1908 *cause = entry->cause();
1909 *cause_msg = entry->cause_msg();
1910 return entry->error();
1911 } else {
1912 return nullptr;
1913 }
1914 }
1915 }
1916
1917 // Add an entry to resolution error table to record an error in resolving or
1918 // validating a nest host. This is used to construct informative error
1919 // messages when IllegalAccessError's occur. If an entry already exists it will
1920 // be updated with the nest host error message.
1921
1922 void SystemDictionary::add_nest_host_error(const constantPoolHandle& pool,
1923 int which,
1924 const char* message) {
1925 {
1926 MutexLocker ml(Thread::current(), SystemDictionary_lock);
1927 ResolutionErrorEntry* entry = ResolutionErrorTable::find_entry(pool, which);
1928 if (entry != nullptr && entry->nest_host_error() == nullptr) {
1929 // An existing entry means we had a true resolution failure (LinkageError) with our nest host, but we
1930 // still want to add the error message for the higher-level access checks to report. We should
1931 // only reach here under the same error condition, so we can ignore the potential race with setting
1932 // the message. If we see it is already set then we can ignore it.
1933 entry->set_nest_host_error(message);
1934 } else {
1935 ResolutionErrorTable::add_entry(pool, which, message);
1936 }
1937 }
1938 }
1939
1940 // Lookup any nest host error
1941 const char* SystemDictionary::find_nest_host_error(const constantPoolHandle& pool, int which) {
1942 {
1943 MutexLocker ml(Thread::current(), SystemDictionary_lock);
1944 ResolutionErrorEntry* entry = ResolutionErrorTable::find_entry(pool, which);
1945 if (entry != nullptr) {
1946 return entry->nest_host_error();
1947 } else {
1948 return nullptr;
1949 }
1950 }
1951 }
1952
1953 // Signature constraints ensure that callers and callees agree about
1954 // the meaning of type names in their signatures. This routine is the
1955 // intake for constraints. It collects them from several places:
1956 //
1957 // * LinkResolver::resolve_method (if check_access is true) requires
1958 // that the resolving class (the caller) and the defining class of
1959 // the resolved method (the callee) agree on each type in the
1960 // method's signature.
1961 //
1962 // * LinkResolver::resolve_interface_method performs exactly the same
1963 // checks.
1964 //
1965 // * LinkResolver::resolve_field requires that the constant pool
1966 // attempting to link to a field agree with the field's defining
1967 // class about the type of the field signature.
1968 //
1969 // * klassVtable::initialize_vtable requires that, when a class
1970 // overrides a vtable entry allocated by a superclass, that the
1971 // overriding method (i.e., the callee) agree with the superclass
1972 // on each type in the method's signature.
1973 //
1974 // * klassItable::initialize_itable requires that, when a class fills
1975 // in its itables, for each non-abstract method installed in an
1976 // itable, the method (i.e., the callee) agree with the interface
1977 // on each type in the method's signature.
1978 //
1979 // All those methods have a boolean (check_access, checkconstraints)
1980 // which turns off the checks. This is used from specialized contexts
1981 // such as bootstrapping, dumping, and debugging.
1982 //
1983 // No direct constraint is placed between the class and its
1984 // supertypes. Constraints are only placed along linked relations
1985 // between callers and callees. When a method overrides or implements
1986 // an abstract method in a supertype (superclass or interface), the
1987 // constraints are placed as if the supertype were the caller to the
1988 // overriding method. (This works well, since callers to the
1989 // supertype have already established agreement between themselves and
1990 // the supertype.) As a result of all this, a class can disagree with
1991 // its supertype about the meaning of a type name, as long as that
1992 // class neither calls a relevant method of the supertype, nor is
1993 // called (perhaps via an override) from the supertype.
1994 //
1995 //
1996 // SystemDictionary::check_signature_loaders(sig, klass_being_linked, l1, l2)
1997 //
1998 // Make sure all class components (including arrays) in the given
1999 // signature will be resolved to the same class in both loaders.
2000 // Returns the name of the type that failed a loader constraint check, or
2001 // null if no constraint failed. No exception except OOME is thrown.
2002 // Arrays are not added to the loader constraint table, their elements are.
2003 Symbol* SystemDictionary::check_signature_loaders(Symbol* signature,
2004 Klass* klass_being_linked,
2005 Handle loader1, Handle loader2,
2006 bool is_method) {
2007 // Nothing to do if loaders are the same.
2008 if (loader1() == loader2()) {
2009 return nullptr;
2010 }
2011
2012 for (SignatureStream ss(signature, is_method); !ss.is_done(); ss.next()) {
2013 if (ss.is_reference()) {
2014 Symbol* sig = ss.as_symbol();
2015 // Note: In the future, if template-like types can take
2016 // arguments, we will want to recognize them and dig out class
2017 // names hiding inside the argument lists.
2018 if (!add_loader_constraint(sig, klass_being_linked, loader1, loader2)) {
2019 return sig;
2020 }
2021 }
2022 }
2023 return nullptr;
2024 }
2025
2026 Method* SystemDictionary::find_method_handle_intrinsic(vmIntrinsicID iid,
2027 Symbol* signature,
2028 TRAPS) {
2029
2030 const int iid_as_int = vmIntrinsics::as_int(iid);
2031 assert(MethodHandles::is_signature_polymorphic(iid) &&
2032 MethodHandles::is_signature_polymorphic_intrinsic(iid) &&
2033 iid != vmIntrinsics::_invokeGeneric,
2034 "must be a known MH intrinsic iid=%d: %s", iid_as_int, vmIntrinsics::name_at(iid));
2035
2036 InvokeMethodKey key(signature, iid_as_int);
2037 Method** met = nullptr;
2038
2039 // We only want one entry in the table for this (signature/id, method) pair but the code
2040 // to create the intrinsic method needs to be outside the lock.
2041 // The first thread claims the entry by adding the key and the other threads wait, until the
2042 // Method has been added as the value.
2043 {
2044 MonitorLocker ml(THREAD, InvokeMethodIntrinsicTable_lock);
2045 while (true) {
2046 bool created;
2047 met = _invoke_method_intrinsic_table->put_if_absent(key, &created);
2048 assert(met != nullptr, "either created or found");
2049 if (*met != nullptr) {
2050 return *met;
2051 } else if (created) {
2052 // The current thread won the race and will try to create the full entry.
2053 break;
2054 } else {
2055 // Another thread beat us to it, so wait for them to complete
2056 // and return *met; or if they hit an error we get another try.
2057 ml.wait();
2058 // Note it is not safe to read *met here as that entry could have
2059 // been deleted, so we must loop and try put_if_absent again.
2060 }
2061 }
2062 }
2063
2064 methodHandle m = Method::make_method_handle_intrinsic(iid, signature, THREAD);
2065 bool throw_error = HAS_PENDING_EXCEPTION;
2066 if (!throw_error && (!Arguments::is_interpreter_only() || iid == vmIntrinsics::_linkToNative)) {
2067 // Generate a compiled form of the MH intrinsic
2068 // linkToNative doesn't have interpreter-specific implementation, so always has to go through compiled version.
2069 AdapterHandlerLibrary::create_native_wrapper(m);
2070 // Check if have the compiled code.
2071 throw_error = (!m->has_compiled_code());
2072 }
2073
2074 {
2075 MonitorLocker ml(THREAD, InvokeMethodIntrinsicTable_lock);
2076 if (throw_error) {
2077 // Remove the entry and let another thread try, or get the same exception.
2078 bool removed = _invoke_method_intrinsic_table->remove(key);
2079 assert(removed, "must be the owner");
2080 ml.notify_all();
2081 } else {
2082 signature->make_permanent(); // The signature is never unloaded.
2083 assert(Arguments::is_interpreter_only() || (m->has_compiled_code() &&
2084 m->code()->entry_point() == m->from_compiled_entry()),
2085 "MH intrinsic invariant");
2086 *met = m(); // insert the element
2087 ml.notify_all();
2088 return m();
2089 }
2090 }
2091
2092 // Throw OOM or the pending exception in the JavaThread
2093 if (throw_error && !HAS_PENDING_EXCEPTION) {
2094 THROW_MSG_NULL(vmSymbols::java_lang_OutOfMemoryError(),
2095 "Out of space in CodeCache for method handle intrinsic");
2096 }
2097 return nullptr;
2098 }
2099
2100 #if INCLUDE_CDS
2101 void SystemDictionary::get_all_method_handle_intrinsics(GrowableArray<Method*>* methods) {
2102 assert(SafepointSynchronize::is_at_safepoint(), "must be");
2103 auto do_method = [&] (InvokeMethodKey& key, Method*& m) {
2104 methods->append(m);
2105 };
2106 _invoke_method_intrinsic_table->iterate_all(do_method);
2107 }
2108
2109 void SystemDictionary::restore_archived_method_handle_intrinsics() {
2110 if (UseSharedSpaces) {
2111 EXCEPTION_MARK;
2112 restore_archived_method_handle_intrinsics_impl(THREAD);
2113 if (HAS_PENDING_EXCEPTION) {
2114 // This is probably caused by OOM -- other parts of the CDS archive have direct pointers to
2115 // the archived method handle intrinsics, so we can't really recover from this failure.
2116 vm_exit_during_initialization(err_msg("Failed to restore archived method handle intrinsics. Try to increase heap size."));
2117 }
2118 }
2119 }
2120
2121 void SystemDictionary::restore_archived_method_handle_intrinsics_impl(TRAPS) {
2122 Array<Method*>* list = MetaspaceShared::archived_method_handle_intrinsics();
2123 for (int i = 0; i < list->length(); i++) {
2124 methodHandle m(THREAD, list->at(i));
2125 Method::restore_archived_method_handle_intrinsic(m, CHECK);
2126 m->constants()->restore_unshareable_info(CHECK);
2127 if (!Arguments::is_interpreter_only() || m->intrinsic_id() == vmIntrinsics::_linkToNative) {
2128 AdapterHandlerLibrary::create_native_wrapper(m);
2129 if (!m->has_compiled_code()) {
2130 ResourceMark rm(THREAD);
2131 vm_exit_during_initialization(err_msg("Failed to initialize method %s", m->external_name()));
2132 }
2133 }
2134
2135 // There's no need to grab the InvokeMethodIntrinsicTable_lock, as we are still very early in
2136 // VM start-up -- in init_globals2() -- so we are still running a single Java thread. It's not
2137 // possible to have a contention.
2138 const int iid_as_int = vmIntrinsics::as_int(m->intrinsic_id());
2139 InvokeMethodKey key(m->signature(), iid_as_int);
2140 bool created = _invoke_method_intrinsic_table->put(key, m());
2141 assert(created, "unexpected contention");
2142 }
2143 }
2144 #endif // INCLUDE_CDS
2145
2146 // Helper for unpacking the return value from linkMethod and linkCallSite.
2147 static Method* unpack_method_and_appendix(Handle mname,
2148 Klass* accessing_klass,
2149 objArrayHandle appendix_box,
2150 Handle* appendix_result,
2151 TRAPS) {
2152 if (mname.not_null()) {
2153 Method* m = java_lang_invoke_MemberName::vmtarget(mname());
2154 if (m != nullptr) {
2155 oop appendix = appendix_box->obj_at(0);
2156 LogTarget(Info, methodhandles) lt;
2157 if (lt.develop_is_enabled()) {
2158 ResourceMark rm(THREAD);
2159 LogStream ls(lt);
2160 ls.print("Linked method=" INTPTR_FORMAT ": ", p2i(m));
2161 m->print_on(&ls);
2162 if (appendix != nullptr) { ls.print("appendix = "); appendix->print_on(&ls); }
2163 ls.cr();
2164 }
2165
2166 (*appendix_result) = Handle(THREAD, appendix);
2167 // the target is stored in the cpCache and if a reference to this
2168 // MemberName is dropped we need a way to make sure the
2169 // class_loader containing this method is kept alive.
2170 methodHandle mh(THREAD, m); // record_dependency can safepoint.
2171 ClassLoaderData* this_key = accessing_klass->class_loader_data();
2172 this_key->record_dependency(m->method_holder());
2173 return mh();
2174 }
2175 }
2176 THROW_MSG_NULL(vmSymbols::java_lang_LinkageError(), "bad value from MethodHandleNatives");
2177 }
2178
2179 Method* SystemDictionary::find_method_handle_invoker(Klass* klass,
2180 Symbol* name,
2181 Symbol* signature,
2182 Klass* accessing_klass,
2183 Handle* appendix_result,
2184 TRAPS) {
2185 guarantee(THREAD->can_call_java(), "");
2186 Handle method_type =
2187 SystemDictionary::find_method_handle_type(signature, accessing_klass, CHECK_NULL);
2188
2189 int ref_kind = JVM_REF_invokeVirtual;
2190 oop name_oop = StringTable::intern(name, CHECK_NULL);
2191 Handle name_str (THREAD, name_oop);
2192 objArrayHandle appendix_box = oopFactory::new_objArray_handle(vmClasses::Object_klass(), 1, CHECK_NULL);
2193 assert(appendix_box->obj_at(0) == nullptr, "");
2194
2195 // This should not happen. JDK code should take care of that.
2196 if (accessing_klass == nullptr || method_type.is_null()) {
2197 THROW_MSG_NULL(vmSymbols::java_lang_InternalError(), "bad invokehandle");
2198 }
2199
2200 // call java.lang.invoke.MethodHandleNatives::linkMethod(... String, MethodType) -> MemberName
2201 JavaCallArguments args;
2202 args.push_oop(Handle(THREAD, accessing_klass->java_mirror()));
2203 args.push_int(ref_kind);
2204 args.push_oop(Handle(THREAD, klass->java_mirror()));
2205 args.push_oop(name_str);
2206 args.push_oop(method_type);
2207 args.push_oop(appendix_box);
2208 JavaValue result(T_OBJECT);
2209 JavaCalls::call_static(&result,
2210 vmClasses::MethodHandleNatives_klass(),
2211 vmSymbols::linkMethod_name(),
2212 vmSymbols::linkMethod_signature(),
2213 &args, CHECK_NULL);
2214 Handle mname(THREAD, result.get_oop());
2215 return unpack_method_and_appendix(mname, accessing_klass, appendix_box, appendix_result, THREAD);
2216 }
2217
2218 // Decide if we can globally cache a lookup of this class, to be returned to any client that asks.
2219 // We must ensure that all class loaders everywhere will reach this class, for any client.
2220 // This is a safe bet for public classes in java.lang, such as Object and String.
2221 // We also include public classes in java.lang.invoke, because they appear frequently in system-level method types.
2222 // Out of an abundance of caution, we do not include any other classes, not even for packages like java.util.
2223 static bool is_always_visible_class(oop mirror) {
2224 Klass* klass = java_lang_Class::as_Klass(mirror);
2225 if (klass->is_objArray_klass()) {
2226 klass = ObjArrayKlass::cast(klass)->bottom_klass(); // check element type
2227 }
2228 if (klass->is_typeArray_klass()) {
2229 return true; // primitive array
2230 }
2231 assert(klass->is_instance_klass(), "%s", klass->external_name());
2232 return klass->is_public() &&
2233 (InstanceKlass::cast(klass)->is_same_class_package(vmClasses::Object_klass()) || // java.lang
2234 InstanceKlass::cast(klass)->is_same_class_package(vmClasses::MethodHandle_klass())); // java.lang.invoke
2235 }
2236
2237 // Find or construct the Java mirror (java.lang.Class instance) for
2238 // the given field type signature, as interpreted relative to the
2239 // given class loader. Handles primitives, void, references, arrays,
2240 // and all other reflectable types, except method types.
2241 // N.B. Code in reflection should use this entry point.
2242 Handle SystemDictionary::find_java_mirror_for_type(Symbol* signature,
2243 Klass* accessing_klass,
2244 SignatureStream::FailureMode failure_mode,
2245 TRAPS) {
2246
2247 Handle class_loader;
2248
2249 // What we have here must be a valid field descriptor,
2250 // and all valid field descriptors are supported.
2251 // Produce the same java.lang.Class that reflection reports.
2252 if (accessing_klass != nullptr) {
2253 class_loader = Handle(THREAD, accessing_klass->class_loader());
2254 }
2255 ResolvingSignatureStream ss(signature, class_loader, false);
2256 oop mirror_oop = ss.as_java_mirror(failure_mode, CHECK_NH);
2257 if (mirror_oop == nullptr) {
2258 return Handle(); // report failure this way
2259 }
2260 Handle mirror(THREAD, mirror_oop);
2261
2262 if (accessing_klass != nullptr) {
2263 // Check accessibility, emulating ConstantPool::verify_constant_pool_resolve.
2264 Klass* sel_klass = java_lang_Class::as_Klass(mirror());
2265 if (sel_klass != nullptr) {
2266 LinkResolver::check_klass_accessibility(accessing_klass, sel_klass, CHECK_NH);
2267 }
2268 }
2269 return mirror;
2270 }
2271
2272
2273 // Ask Java code to find or construct a java.lang.invoke.MethodType for the given
2274 // signature, as interpreted relative to the given class loader.
2275 // Because of class loader constraints, all method handle usage must be
2276 // consistent with this loader.
2277 Handle SystemDictionary::find_method_handle_type(Symbol* signature,
2278 Klass* accessing_klass,
2279 TRAPS) {
2280 Handle empty;
2281 OopHandle* o;
2282 {
2283 MutexLocker ml(THREAD, InvokeMethodTypeTable_lock);
2284 o = _invoke_method_type_table->get(signature);
2285 }
2286
2287 if (o != nullptr) {
2288 oop mt = o->resolve();
2289 assert(java_lang_invoke_MethodType::is_instance(mt), "");
2290 return Handle(THREAD, mt);
2291 } else if (!THREAD->can_call_java()) {
2292 warning("SystemDictionary::find_method_handle_type called from compiler thread"); // FIXME
2293 return Handle(); // do not attempt from within compiler, unless it was cached
2294 }
2295
2296 Handle class_loader;
2297 if (accessing_klass != nullptr) {
2298 class_loader = Handle(THREAD, accessing_klass->class_loader());
2299 }
2300 bool can_be_cached = true;
2301 int npts = ArgumentCount(signature).size();
2302 objArrayHandle pts = oopFactory::new_objArray_handle(vmClasses::Class_klass(), npts, CHECK_(empty));
2303 int arg = 0;
2304 Handle rt; // the return type from the signature
2305 ResourceMark rm(THREAD);
2306 for (SignatureStream ss(signature); !ss.is_done(); ss.next()) {
2307 oop mirror = nullptr;
2308 if (can_be_cached) {
2309 // Use neutral class loader to lookup candidate classes to be placed in the cache.
2310 mirror = ss.as_java_mirror(Handle(), SignatureStream::ReturnNull, CHECK_(empty));
2311 if (mirror == nullptr || (ss.is_reference() && !is_always_visible_class(mirror))) {
2312 // Fall back to accessing_klass context.
2313 can_be_cached = false;
2314 }
2315 }
2316 if (!can_be_cached) {
2317 // Resolve, throwing a real error if it doesn't work.
2318 mirror = ss.as_java_mirror(class_loader, SignatureStream::NCDFError, CHECK_(empty));
2319 }
2320 assert(mirror != nullptr, "%s", ss.as_symbol()->as_C_string());
2321 if (ss.at_return_type())
2322 rt = Handle(THREAD, mirror);
2323 else
2324 pts->obj_at_put(arg++, mirror);
2325
2326 // Check accessibility.
2327 if (!java_lang_Class::is_primitive(mirror) && accessing_klass != nullptr) {
2328 Klass* sel_klass = java_lang_Class::as_Klass(mirror);
2329 mirror = nullptr; // safety
2330 // Emulate ConstantPool::verify_constant_pool_resolve.
2331 LinkResolver::check_klass_accessibility(accessing_klass, sel_klass, CHECK_(empty));
2332 }
2333 }
2334 assert(arg == npts, "");
2335
2336 // call java.lang.invoke.MethodHandleNatives::findMethodHandleType(Class rt, Class[] pts) -> MethodType
2337 JavaCallArguments args(Handle(THREAD, rt()));
2338 args.push_oop(pts);
2339 JavaValue result(T_OBJECT);
2340 JavaCalls::call_static(&result,
2341 vmClasses::MethodHandleNatives_klass(),
2342 vmSymbols::findMethodHandleType_name(),
2343 vmSymbols::findMethodHandleType_signature(),
2344 &args, CHECK_(empty));
2345 Handle method_type(THREAD, result.get_oop());
2346
2347 if (can_be_cached) {
2348 // We can cache this MethodType inside the JVM.
2349 MutexLocker ml(THREAD, InvokeMethodTypeTable_lock);
2350 bool created = false;
2351 assert(method_type != nullptr, "unexpected null");
2352 OopHandle* h = _invoke_method_type_table->get(signature);
2353 if (h == nullptr) {
2354 signature->make_permanent(); // The signature is never unloaded.
2355 OopHandle elem = OopHandle(Universe::vm_global(), method_type());
2356 bool created = _invoke_method_type_table->put(signature, elem);
2357 assert(created, "better be created");
2358 }
2359 }
2360 // report back to the caller with the MethodType
2361 return method_type;
2362 }
2363
2364 Handle SystemDictionary::find_field_handle_type(Symbol* signature,
2365 Klass* accessing_klass,
2366 TRAPS) {
2367 Handle empty;
2368 ResourceMark rm(THREAD);
2369 SignatureStream ss(signature, /*is_method=*/ false);
2370 if (!ss.is_done()) {
2371 Handle class_loader;
2372 if (accessing_klass != nullptr) {
2373 class_loader = Handle(THREAD, accessing_klass->class_loader());
2374 }
2375 oop mirror = ss.as_java_mirror(class_loader, SignatureStream::NCDFError, CHECK_(empty));
2376 ss.next();
2377 if (ss.is_done()) {
2378 return Handle(THREAD, mirror);
2379 }
2380 }
2381 return empty;
2382 }
2383
2384 // Ask Java code to find or construct a method handle constant.
2385 Handle SystemDictionary::link_method_handle_constant(Klass* caller,
2386 int ref_kind, //e.g., JVM_REF_invokeVirtual
2387 Klass* callee,
2388 Symbol* name,
2389 Symbol* signature,
2390 TRAPS) {
2391 Handle empty;
2392 if (caller == nullptr) {
2393 THROW_MSG_(vmSymbols::java_lang_InternalError(), "bad MH constant", empty);
2394 }
2395 Handle name_str = java_lang_String::create_from_symbol(name, CHECK_(empty));
2396 Handle signature_str = java_lang_String::create_from_symbol(signature, CHECK_(empty));
2397
2398 // Put symbolic info from the MH constant into freshly created MemberName and resolve it.
2399 Handle mname = vmClasses::MemberName_klass()->allocate_instance_handle(CHECK_(empty));
2400 java_lang_invoke_MemberName::set_clazz(mname(), callee->java_mirror());
2401 java_lang_invoke_MemberName::set_name (mname(), name_str());
2402 java_lang_invoke_MemberName::set_type (mname(), signature_str());
2403 java_lang_invoke_MemberName::set_flags(mname(), MethodHandles::ref_kind_to_flags(ref_kind));
2404
2405 if (ref_kind == JVM_REF_invokeVirtual &&
2406 MethodHandles::is_signature_polymorphic_public_name(callee, name)) {
2407 // Skip resolution for public signature polymorphic methods such as
2408 // j.l.i.MethodHandle.invoke()/invokeExact() and those on VarHandle
2409 // They require appendix argument which MemberName resolution doesn't handle.
2410 // There's special logic on JDK side to handle them
2411 // (see MethodHandles.linkMethodHandleConstant() and MethodHandles.findVirtualForMH()).
2412 } else {
2413 MethodHandles::resolve_MemberName(mname, caller, 0, false /*speculative_resolve*/, CHECK_(empty));
2414 }
2415
2416 // After method/field resolution succeeded, it's safe to resolve MH signature as well.
2417 Handle type = MethodHandles::resolve_MemberName_type(mname, caller, CHECK_(empty));
2418
2419 // call java.lang.invoke.MethodHandleNatives::linkMethodHandleConstant(Class caller, int refKind, Class callee, String name, Object type) -> MethodHandle
2420 JavaCallArguments args;
2421 args.push_oop(Handle(THREAD, caller->java_mirror())); // the referring class
2422 args.push_int(ref_kind);
2423 args.push_oop(Handle(THREAD, callee->java_mirror())); // the target class
2424 args.push_oop(name_str);
2425 args.push_oop(type);
2426 JavaValue result(T_OBJECT);
2427 JavaCalls::call_static(&result,
2428 vmClasses::MethodHandleNatives_klass(),
2429 vmSymbols::linkMethodHandleConstant_name(),
2430 vmSymbols::linkMethodHandleConstant_signature(),
2431 &args, CHECK_(empty));
2432 return Handle(THREAD, result.get_oop());
2433 }
2434
2435 // Ask Java to run a bootstrap method, in order to create a dynamic call site
2436 // while linking an invokedynamic op, or compute a constant for Dynamic_info CP entry
2437 // with linkage results being stored back into the bootstrap specifier.
2438 void SystemDictionary::invoke_bootstrap_method(BootstrapInfo& bootstrap_specifier, TRAPS) {
2439 // Resolve the bootstrap specifier, its name, type, and static arguments
2440 bootstrap_specifier.resolve_bsm(CHECK);
2441
2442 // This should not happen. JDK code should take care of that.
2443 if (bootstrap_specifier.caller() == nullptr || bootstrap_specifier.type_arg().is_null()) {
2444 THROW_MSG(vmSymbols::java_lang_InternalError(), "Invalid bootstrap method invocation with no caller or type argument");
2445 }
2446
2447 bool is_indy = bootstrap_specifier.is_method_call();
2448 objArrayHandle appendix_box;
2449 if (is_indy) {
2450 // Some method calls may require an appendix argument. Arrange to receive it.
2451 appendix_box = oopFactory::new_objArray_handle(vmClasses::Object_klass(), 1, CHECK);
2452 assert(appendix_box->obj_at(0) == nullptr, "");
2453 }
2454
2455 // call condy: java.lang.invoke.MethodHandleNatives::linkDynamicConstant(caller, bsm, type, info)
2456 // indy: java.lang.invoke.MethodHandleNatives::linkCallSite(caller, bsm, name, mtype, info, &appendix)
2457 JavaCallArguments args;
2458 args.push_oop(Handle(THREAD, bootstrap_specifier.caller_mirror()));
2459 args.push_oop(bootstrap_specifier.bsm());
2460 args.push_oop(bootstrap_specifier.name_arg());
2461 args.push_oop(bootstrap_specifier.type_arg());
2462 args.push_oop(bootstrap_specifier.arg_values());
2463 if (is_indy) {
2464 args.push_oop(appendix_box);
2465 }
2466 JavaValue result(T_OBJECT);
2467 JavaCalls::call_static(&result,
2468 vmClasses::MethodHandleNatives_klass(),
2469 is_indy ? vmSymbols::linkCallSite_name() : vmSymbols::linkDynamicConstant_name(),
2470 is_indy ? vmSymbols::linkCallSite_signature() : vmSymbols::linkDynamicConstant_signature(),
2471 &args, CHECK);
2472
2473 Handle value(THREAD, result.get_oop());
2474 if (is_indy) {
2475 Handle appendix;
2476 Method* method = unpack_method_and_appendix(value,
2477 bootstrap_specifier.caller(),
2478 appendix_box,
2479 &appendix, CHECK);
2480 methodHandle mh(THREAD, method);
2481 bootstrap_specifier.set_resolved_method(mh, appendix);
2482 } else {
2483 bootstrap_specifier.set_resolved_value(value);
2484 }
2485
2486 // sanity check
2487 assert(bootstrap_specifier.is_resolved() ||
2488 (bootstrap_specifier.is_method_call() &&
2489 bootstrap_specifier.resolved_method().not_null()), "bootstrap method call failed");
2490 }
2491
2492
2493 bool SystemDictionary::is_nonpublic_Object_method(Method* m) {
2494 assert(m != nullptr, "Unexpected nullptr Method*");
2495 return !m->is_public() && m->method_holder() == vmClasses::Object_klass();
2496 }
2497
2498 // ----------------------------------------------------------------------------
2499
2500 void SystemDictionary::print_on(outputStream *st) {
2501 CDS_ONLY(SystemDictionaryShared::print_on(st));
2502 GCMutexLocker mu(SystemDictionary_lock);
2503
2504 ClassLoaderDataGraph::print_dictionary(st);
2505
2506 // Placeholders
2507 PlaceholderTable::print_on(st);
2508 st->cr();
2509
2510 // loader constraints - print under SD_lock
2511 LoaderConstraintTable::print_on(st);
2512 st->cr();
2513 }
2514
2515 void SystemDictionary::print() { print_on(tty); }
2516
2517 void SystemDictionary::verify() {
2518
2519 GCMutexLocker mu(SystemDictionary_lock);
2520
2521 // Verify dictionary
2522 ClassLoaderDataGraph::verify_dictionary();
2523
2524 // Verify constraint table
2525 LoaderConstraintTable::verify();
2526 }
2527
2528 void SystemDictionary::dump(outputStream *st, bool verbose) {
2529 assert_locked_or_safepoint(SystemDictionary_lock);
2530 if (verbose) {
2531 print_on(st);
2532 } else {
2533 CDS_ONLY(SystemDictionaryShared::print_table_statistics(st));
2534 ClassLoaderDataGraph::print_table_statistics(st);
2535 LoaderConstraintTable::print_table_statistics(st);
2536 }
2537 }
2538
2539 // Utility for dumping dictionaries.
2540 SystemDictionaryDCmd::SystemDictionaryDCmd(outputStream* output, bool heap) :
2541 DCmdWithParser(output, heap),
2542 _verbose("-verbose", "Dump the content of each dictionary entry for all class loaders",
2543 "BOOLEAN", false, "false") {
2544 _dcmdparser.add_dcmd_option(&_verbose);
2545 }
2546
2547 void SystemDictionaryDCmd::execute(DCmdSource source, TRAPS) {
2548 VM_DumpHashtable dumper(output(), VM_DumpHashtable::DumpSysDict,
2549 _verbose.value());
2550 VMThread::execute(&dumper);
2551 }