1 /*
2 * Copyright (c) 1997, 2024, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
24
25 #include "precompiled.hpp"
26 #include "cds/aotLinkedClassBulkLoader.hpp"
27 #include "cds/cdsConfig.hpp"
28 #include "cds/heapShared.hpp"
29 #include "classfile/classFileParser.hpp"
30 #include "classfile/classFileStream.hpp"
31 #include "classfile/classLoader.hpp"
32 #include "classfile/classLoaderData.inline.hpp"
33 #include "classfile/classLoaderDataGraph.inline.hpp"
34 #include "classfile/classLoaderExt.hpp"
35 #include "classfile/classLoadInfo.hpp"
36 #include "classfile/dictionary.hpp"
37 #include "classfile/javaClasses.inline.hpp"
38 #include "classfile/klassFactory.hpp"
39 #include "classfile/loaderConstraints.hpp"
40 #include "classfile/modules.hpp"
41 #include "classfile/packageEntry.hpp"
42 #include "classfile/placeholders.hpp"
43 #include "classfile/protectionDomainCache.hpp"
44 #include "classfile/resolutionErrors.hpp"
45 #include "classfile/stringTable.hpp"
46 #include "classfile/symbolTable.hpp"
47 #include "classfile/systemDictionary.hpp"
48 #include "classfile/vmClasses.hpp"
49 #include "classfile/vmSymbols.hpp"
50 #include "gc/shared/gcTraceTime.inline.hpp"
51 #include "interpreter/bootstrapInfo.hpp"
52 #include "jfr/jfrEvents.hpp"
53 #include "jvm.h"
54 #include "logging/log.hpp"
55 #include "logging/logStream.hpp"
56 #include "memory/metaspaceClosure.hpp"
57 #include "memory/oopFactory.hpp"
58 #include "memory/resourceArea.hpp"
59 #include "memory/universe.hpp"
60 #include "oops/access.inline.hpp"
61 #include "oops/instanceKlass.hpp"
62 #include "oops/klass.inline.hpp"
63 #include "oops/method.inline.hpp"
64 #include "oops/objArrayKlass.hpp"
65 #include "oops/objArrayOop.inline.hpp"
66 #include "oops/oop.inline.hpp"
67 #include "oops/oop.hpp"
68 #include "oops/oopHandle.hpp"
69 #include "oops/oopHandle.inline.hpp"
70 #include "oops/symbol.hpp"
71 #include "oops/typeArrayKlass.hpp"
72 #include "prims/jvmtiExport.hpp"
73 #include "prims/methodHandles.hpp"
74 #include "runtime/arguments.hpp"
75 #include "runtime/atomic.hpp"
76 #include "runtime/handles.inline.hpp"
77 #include "runtime/java.hpp"
78 #include "runtime/javaCalls.hpp"
79 #include "runtime/mutexLocker.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 if (CDSConfig::is_dumping_final_static_archive()) {
144 AOTLinkedClassBulkLoader::load_platform_classes(THREAD);
145 }
146 } else {
147 // It must have been restored from the archived module graph
148 assert(CDSConfig::is_using_archive(), "must be");
149 assert(CDSConfig::is_using_full_module_graph(), "must be");
150 DEBUG_ONLY(
151 oop platform_loader = get_platform_class_loader_impl(CHECK);
152 assert(_java_platform_loader.resolve() == platform_loader, "must be");
153 )
154 }
155
156 if (_java_system_loader.is_empty()) {
157 oop system_loader = get_system_class_loader_impl(CHECK);
158 _java_system_loader = OopHandle(Universe::vm_global(), system_loader);
159 if (CDSConfig::is_dumping_final_static_archive()) {
160 AOTLinkedClassBulkLoader::load_app_classes(THREAD);
161 }
162 } else {
163 // It must have been restored from the archived module graph
164 assert(CDSConfig::is_using_archive(), "must be");
165 assert(CDSConfig::is_using_full_module_graph(), "must be");
166 DEBUG_ONLY(
167 oop system_loader = get_system_class_loader_impl(CHECK);
168 assert(_java_system_loader.resolve() == system_loader, "must be");
169 )
170 }
171 }
172
173 oop SystemDictionary::get_system_class_loader_impl(TRAPS) {
174 JavaValue result(T_OBJECT);
175 InstanceKlass* class_loader_klass = vmClasses::ClassLoader_klass();
176 JavaCalls::call_static(&result,
177 class_loader_klass,
178 vmSymbols::getSystemClassLoader_name(),
179 vmSymbols::void_classloader_signature(),
180 CHECK_NULL);
181 return result.get_oop();
182 }
183
184 oop SystemDictionary::get_platform_class_loader_impl(TRAPS) {
185 JavaValue result(T_OBJECT);
186 InstanceKlass* class_loader_klass = vmClasses::ClassLoader_klass();
187 JavaCalls::call_static(&result,
188 class_loader_klass,
189 vmSymbols::getPlatformClassLoader_name(),
190 vmSymbols::void_classloader_signature(),
191 CHECK_NULL);
192 return result.get_oop();
193 }
194
195 // Helper function
196 inline ClassLoaderData* class_loader_data(Handle class_loader) {
197 return ClassLoaderData::class_loader_data(class_loader());
198 }
199
200 ClassLoaderData* SystemDictionary::register_loader(Handle class_loader, bool create_mirror_cld) {
201 if (create_mirror_cld) {
202 // Add a new class loader data to the graph.
203 return ClassLoaderDataGraph::add(class_loader, true);
204 } else {
205 return (class_loader() == nullptr) ? ClassLoaderData::the_null_class_loader_data() :
206 ClassLoaderDataGraph::find_or_create(class_loader);
207 }
208 }
209
210 void SystemDictionary::set_system_loader(ClassLoaderData *cld) {
211 assert(_java_system_loader.is_empty(), "already set!");
212 _java_system_loader = cld->class_loader_handle();
213
214 }
215
216 void SystemDictionary::set_platform_loader(ClassLoaderData *cld) {
217 assert(_java_platform_loader.is_empty(), "already set!");
218 _java_platform_loader = cld->class_loader_handle();
219 }
220
221 // ----------------------------------------------------------------------------
222 // Parallel class loading check
223
224 static bool is_parallelCapable(Handle class_loader) {
225 if (class_loader.is_null()) return true;
226 return java_lang_ClassLoader::parallelCapable(class_loader());
227 }
228 // ----------------------------------------------------------------------------
229 // ParallelDefineClass flag does not apply to bootclass loader
230 static bool is_parallelDefine(Handle class_loader) {
231 if (class_loader.is_null()) return false;
232 if (AllowParallelDefineClass && java_lang_ClassLoader::parallelCapable(class_loader())) {
233 return true;
234 }
235 return false;
236 }
237
238 // Returns true if the passed class loader is the builtin application class loader
239 // or a custom system class loader. A customer system class loader can be
240 // specified via -Djava.system.class.loader.
241 bool SystemDictionary::is_system_class_loader(oop class_loader) {
242 if (class_loader == nullptr) {
243 return false;
244 }
245 return (class_loader->klass() == vmClasses::jdk_internal_loader_ClassLoaders_AppClassLoader_klass() ||
246 class_loader == _java_system_loader.peek());
247 }
248
249 // Returns true if the passed class loader is the platform class loader.
250 bool SystemDictionary::is_platform_class_loader(oop class_loader) {
251 if (class_loader == nullptr) {
252 return false;
253 }
254 return (class_loader->klass() == vmClasses::jdk_internal_loader_ClassLoaders_PlatformClassLoader_klass());
255 }
256
257 Handle SystemDictionary::get_loader_lock_or_null(Handle class_loader) {
258 // If class_loader is null or parallelCapable, the JVM doesn't acquire a lock while loading.
259 if (is_parallelCapable(class_loader)) {
260 return Handle();
261 } else {
262 return class_loader;
263 }
264 }
265
266 // ----------------------------------------------------------------------------
267 // Resolving of classes
268
269 Symbol* SystemDictionary::class_name_symbol(const char* name, Symbol* exception, TRAPS) {
270 if (name == nullptr) {
271 THROW_MSG_NULL(exception, "No class name given");
272 }
273 size_t name_len = strlen(name);
274 if (name_len > static_cast<size_t>(Symbol::max_length())) {
275 // It's impossible to create this class; the name cannot fit
276 // into the constant pool. If necessary report an abridged name
277 // in the exception message.
278 if (name_len > static_cast<size_t>(MaxStringPrintSize)) {
279 Exceptions::fthrow(THREAD_AND_LOCATION, exception,
280 "Class name exceeds maximum length of %d: %.*s ... (%zu characters omitted) ... %.*s",
281 Symbol::max_length(),
282 MaxStringPrintSize / 2,
283 name,
284 name_len - 2 * (MaxStringPrintSize / 2), // allows for odd value
285 MaxStringPrintSize / 2,
286 name + name_len - MaxStringPrintSize / 2);
287 }
288 else {
289 Exceptions::fthrow(THREAD_AND_LOCATION, exception,
290 "Class name exceeds maximum length of %d: %s",
291 Symbol::max_length(),
292 name);
293 }
294 return nullptr;
295 }
296 // Callers should ensure that the name is never an illegal UTF8 string.
297 assert(UTF8::is_legal_utf8((const unsigned char*)name, name_len, false),
298 "Class name is not a valid utf8 string.");
299
300 // Make a new symbol for the class name.
301 return SymbolTable::new_symbol(name);
302 }
303
304 #ifdef ASSERT
305 // Used to verify that class loading succeeded in adding k to the dictionary.
306 static void verify_dictionary_entry(Symbol* class_name, InstanceKlass* k) {
307 MutexLocker mu(SystemDictionary_lock);
308 ClassLoaderData* loader_data = k->class_loader_data();
309 Dictionary* dictionary = loader_data->dictionary();
310 assert(class_name == k->name(), "Must be the same");
311 InstanceKlass* kk = dictionary->find_class(JavaThread::current(), class_name);
312 assert(kk == k, "should be present in dictionary");
313 }
314 #endif
315
316 static void handle_resolution_exception(Symbol* class_name, bool throw_error, TRAPS) {
317 if (HAS_PENDING_EXCEPTION) {
318 // If we have a pending exception we forward it to the caller, unless throw_error is true,
319 // in which case we have to check whether the pending exception is a ClassNotFoundException,
320 // and convert it to a NoClassDefFoundError and chain the original ClassNotFoundException.
321 if (throw_error && PENDING_EXCEPTION->is_a(vmClasses::ClassNotFoundException_klass())) {
322 ResourceMark rm(THREAD);
323 Handle e(THREAD, PENDING_EXCEPTION);
324 CLEAR_PENDING_EXCEPTION;
325 THROW_MSG_CAUSE(vmSymbols::java_lang_NoClassDefFoundError(), class_name->as_C_string(), e);
326 } else {
327 return; // the caller will throw the incoming exception
328 }
329 }
330 // If the class is not found, ie, caller has checked that klass is null, throw the appropriate
331 // error or exception depending on the value of throw_error.
332 ResourceMark rm(THREAD);
333 if (throw_error) {
334 THROW_MSG(vmSymbols::java_lang_NoClassDefFoundError(), class_name->as_C_string());
335 } else {
336 THROW_MSG(vmSymbols::java_lang_ClassNotFoundException(), class_name->as_C_string());
337 }
338 }
339
340 // Forwards to resolve_or_null
341
342 Klass* SystemDictionary::resolve_or_fail(Symbol* class_name, Handle class_loader, Handle protection_domain,
343 bool throw_error, TRAPS) {
344 Klass* klass = resolve_or_null(class_name, class_loader, protection_domain, THREAD);
345 // Check for pending exception or null klass, and throw exception
346 if (HAS_PENDING_EXCEPTION || klass == nullptr) {
347 handle_resolution_exception(class_name, throw_error, CHECK_NULL);
348 }
349 return klass;
350 }
351
352 // Forwards to resolve_array_class_or_null or resolve_instance_class_or_null
353
354 Klass* SystemDictionary::resolve_or_null(Symbol* class_name, Handle class_loader, Handle protection_domain, TRAPS) {
355 if (Signature::is_array(class_name)) {
356 return resolve_array_class_or_null(class_name, class_loader, protection_domain, THREAD);
357 } else {
358 assert(class_name != nullptr && !Signature::is_array(class_name), "must be");
359 if (Signature::has_envelope(class_name)) {
360 ResourceMark rm(THREAD);
361 // Ignore wrapping L and ;.
362 TempNewSymbol name = SymbolTable::new_symbol(class_name->as_C_string() + 1,
363 class_name->utf8_length() - 2);
364 return resolve_instance_class_or_null(name, class_loader, protection_domain, THREAD);
365 } else {
366 return resolve_instance_class_or_null(class_name, class_loader, protection_domain, THREAD);
367 }
368 }
369 }
370
371 // Forwards to resolve_instance_class_or_null
372
373 Klass* SystemDictionary::resolve_array_class_or_null(Symbol* class_name,
374 Handle class_loader,
375 Handle protection_domain,
376 TRAPS) {
377 assert(Signature::is_array(class_name), "must be array");
378 ResourceMark rm(THREAD);
379 SignatureStream ss(class_name, false);
380 int ndims = ss.skip_array_prefix(); // skip all '['s
381 Klass* k = nullptr;
382 BasicType t = ss.type();
383 if (ss.has_envelope()) {
384 Symbol* obj_class = ss.as_symbol();
385 k = SystemDictionary::resolve_instance_class_or_null(obj_class,
386 class_loader,
387 protection_domain,
388 CHECK_NULL);
389 if (k != nullptr) {
390 k = k->array_klass(ndims, CHECK_NULL);
391 }
392 } else {
393 k = Universe::typeArrayKlass(t);
394 k = k->array_klass(ndims, CHECK_NULL);
395 }
396 return k;
397 }
398
399 static inline void log_circularity_error(Symbol* name, PlaceholderEntry* probe) {
400 LogTarget(Debug, class, load, placeholders) lt;
401 if (lt.is_enabled()) {
402 ResourceMark rm;
403 LogStream ls(lt);
404 ls.print("ClassCircularityError detected for placeholder entry %s", name->as_C_string());
405 probe->print_on(&ls);
406 ls.cr();
407 }
408 }
409
410 // Must be called for any superclass or superinterface resolution
411 // during class definition to allow class circularity checking
412 // superinterface callers:
413 // parse_interfaces - from defineClass
414 // superclass callers:
415 // ClassFileParser - from defineClass
416 // load_shared_class - while loading a class from shared archive
417 // resolve_instance_class_or_null:
418 // via: handle_parallel_super_load
419 // when resolving a class that has an existing placeholder with
420 // a saved superclass [i.e. a defineClass is currently in progress]
421 // If another thread is trying to resolve the class, it must do
422 // superclass checks on its own thread to catch class circularity and
423 // to avoid deadlock.
424 //
425 // resolve_with_circularity_detection adds a DETECT_CIRCULARITY placeholder to the placeholder table before calling
426 // resolve_instance_class_or_null. ClassCircularityError is detected when a DETECT_CIRCULARITY or LOAD_INSTANCE
427 // placeholder for the same thread, class, classloader is found.
428 // This can be seen with logging option: -Xlog:class+load+placeholders=debug.
429 //
430 InstanceKlass* SystemDictionary::resolve_with_circularity_detection(Symbol* class_name,
431 Symbol* next_name,
432 Handle class_loader,
433 Handle protection_domain,
434 bool is_superclass,
435 TRAPS) {
436
437 assert(next_name != nullptr, "null superclass for resolving");
438 assert(!Signature::is_array(next_name), "invalid superclass name");
439 #if INCLUDE_CDS
440 if (CDSConfig::is_dumping_static_archive()) {
441 // Special processing for handling UNREGISTERED shared classes.
442 InstanceKlass* k = SystemDictionaryShared::lookup_super_for_unregistered_class(class_name,
443 next_name, is_superclass);
444 if (k) {
445 return k;
446 }
447 }
448 #endif // INCLUDE_CDS
449
450 // If class_name is already loaded, just return the superclass or superinterface.
451 // Make sure there's a placeholder for the class_name before resolving.
452 // This is used as a claim that this thread is currently loading superclass/classloader
453 // and for ClassCircularity checks.
454
455 ClassLoaderData* loader_data = class_loader_data(class_loader);
456 Dictionary* dictionary = loader_data->dictionary();
457
458 // can't throw error holding a lock
459 bool throw_circularity_error = false;
460 {
461 MutexLocker mu(THREAD, SystemDictionary_lock);
462 InstanceKlass* klassk = dictionary->find_class(THREAD, class_name);
463 InstanceKlass* quicksuperk;
464 // To support parallel loading: if class is done loading, just return the superclass
465 // if the next_name matches class->super()->name() and if the class loaders match.
466 if (klassk != nullptr && is_superclass &&
467 ((quicksuperk = klassk->java_super()) != nullptr) &&
468 ((quicksuperk->name() == next_name) &&
469 (quicksuperk->class_loader() == class_loader()))) {
470 return quicksuperk;
471 } else {
472 // Must check ClassCircularity before checking if superclass is already loaded.
473 PlaceholderEntry* probe = PlaceholderTable::get_entry(class_name, loader_data);
474 if (probe && probe->check_seen_thread(THREAD, PlaceholderTable::DETECT_CIRCULARITY)) {
475 log_circularity_error(class_name, probe);
476 throw_circularity_error = true;
477 }
478 }
479
480 if (!throw_circularity_error) {
481 // Be careful not to exit resolve_with_circularity_detection without removing this placeholder.
482 PlaceholderEntry* newprobe = PlaceholderTable::find_and_add(class_name,
483 loader_data,
484 PlaceholderTable::DETECT_CIRCULARITY,
485 next_name, THREAD);
486 }
487 }
488
489 if (throw_circularity_error) {
490 ResourceMark rm(THREAD);
491 THROW_MSG_NULL(vmSymbols::java_lang_ClassCircularityError(), class_name->as_C_string());
492 }
493
494 // Resolve the superclass or superinterface, check results on return
495 InstanceKlass* superk =
496 SystemDictionary::resolve_instance_class_or_null(next_name,
497 class_loader,
498 protection_domain,
499 THREAD);
500
501 // Clean up placeholder entry.
502 {
503 MutexLocker mu(THREAD, SystemDictionary_lock);
504 PlaceholderTable::find_and_remove(class_name, loader_data, PlaceholderTable::DETECT_CIRCULARITY, THREAD);
505 SystemDictionary_lock->notify_all();
506 }
507
508 // Check for pending exception or null superk, and throw exception
509 if (HAS_PENDING_EXCEPTION || superk == nullptr) {
510 handle_resolution_exception(next_name, true, CHECK_NULL);
511 }
512
513 return superk;
514 }
515
516 // If the class in is in the placeholder table, class loading is in progress.
517 // For cases where the application changes threads to load classes, it
518 // is critical to ClassCircularity detection that we try loading
519 // the superclass on the new thread internally, so we do parallel
520 // superclass loading here. This avoids deadlock for ClassCircularity
521 // detection for parallelCapable class loaders that lock on a per-class lock.
522 static void handle_parallel_super_load(Symbol* name,
523 Symbol* superclassname,
524 Handle class_loader,
525 Handle protection_domain, TRAPS) {
526
527 // The result superk is not used; resolve_with_circularity_detection is called for circularity check only.
528 // This passes true to is_superclass even though it might not be the super class in order to perform the
529 // optimization anyway.
530 Klass* superk = SystemDictionary::resolve_with_circularity_detection(name,
531 superclassname,
532 class_loader,
533 protection_domain,
534 true,
535 CHECK);
536 }
537
538 // Bootstrap and non-parallel capable class loaders use the LOAD_INSTANCE placeholder to
539 // wait for parallel class loading and/or to check for circularity error for Xcomp when loading.
540 static bool needs_load_placeholder(Handle class_loader) {
541 return class_loader.is_null() || !is_parallelCapable(class_loader);
542 }
543
544 // Check for other threads loading this class either to throw CCE or wait in the case of the boot loader.
545 static InstanceKlass* handle_parallel_loading(JavaThread* current,
546 Symbol* name,
547 ClassLoaderData* loader_data,
548 bool must_wait_for_class_loading,
549 bool* throw_circularity_error) {
550 PlaceholderEntry* oldprobe = PlaceholderTable::get_entry(name, loader_data);
551 if (oldprobe != nullptr) {
552 // -Xcomp calls load_signature_classes which might result in loading
553 // a class that's already in the process of loading, so we detect CCE here also.
554 // Only need check_seen_thread once, not on each loop
555 if (oldprobe->check_seen_thread(current, PlaceholderTable::LOAD_INSTANCE)) {
556 log_circularity_error(name, oldprobe);
557 *throw_circularity_error = true;
558 return nullptr;
559 } else if (must_wait_for_class_loading) {
560 // Wait until the first thread has finished loading this class. Also wait until all the
561 // threads trying to load its superclass have removed their placeholders.
562 while (oldprobe != nullptr &&
563 (oldprobe->instance_load_in_progress() || oldprobe->circularity_detection_in_progress())) {
564
565 // LOAD_INSTANCE placeholders are used to implement parallel capable class loading
566 // for the bootclass loader.
567 SystemDictionary_lock->wait();
568
569 // Check if classloading completed while we were waiting
570 InstanceKlass* check = loader_data->dictionary()->find_class(current, name);
571 if (check != nullptr) {
572 // Klass is already loaded, so just return it
573 return check;
574 }
575 // check if other thread failed to load and cleaned up
576 oldprobe = PlaceholderTable::get_entry(name, loader_data);
577 }
578 }
579 }
580 return nullptr;
581 }
582
583 void SystemDictionary::post_class_load_event(EventClassLoad* event, const InstanceKlass* k, const ClassLoaderData* init_cld) {
584 assert(event != nullptr, "invariant");
585 assert(k != nullptr, "invariant");
586 event->set_loadedClass(k);
587 event->set_definingClassLoader(k->class_loader_data());
588 event->set_initiatingClassLoader(init_cld);
589 event->commit();
590 }
591
592 // SystemDictionary::resolve_instance_class_or_null is the main function for class name resolution.
593 // After checking if the InstanceKlass already exists, it checks for ClassCircularityError and
594 // whether the thread must wait for loading in parallel. It eventually calls load_instance_class,
595 // which will load the class via the bootstrap loader or call ClassLoader.loadClass().
596 // This can return null, an exception or an InstanceKlass.
597 InstanceKlass* SystemDictionary::resolve_instance_class_or_null(Symbol* name,
598 Handle class_loader,
599 Handle protection_domain,
600 TRAPS) {
601 // name must be in the form of "java/lang/Object" -- cannot be "Ljava/lang/Object;"
602 DEBUG_ONLY(ResourceMark rm(THREAD));
603 assert(name != nullptr && !Signature::is_array(name) &&
604 !Signature::has_envelope(name), "invalid class name: %s", name == nullptr ? "nullptr" : name->as_C_string());
605
606 EventClassLoad class_load_start_event;
607
608 HandleMark hm(THREAD);
609
610 // Fix for 4474172; see evaluation for more details
611 class_loader = Handle(THREAD, java_lang_ClassLoader::non_reflection_class_loader(class_loader()));
612 ClassLoaderData* loader_data = register_loader(class_loader);
613 Dictionary* dictionary = loader_data->dictionary();
614
615 // Do lookup to see if class already exists and the protection domain
616 // has the right access.
617 // This call uses find which checks protection domain already matches
618 // All subsequent calls use find_class, and set loaded_class so that
619 // before we return a result, we call out to java to check for valid protection domain.
620 InstanceKlass* probe = dictionary->find(THREAD, name, protection_domain);
621 if (probe != nullptr) return probe;
622
623 // Non-bootstrap class loaders will call out to class loader and
624 // define via jvm/jni_DefineClass which will acquire the
625 // class loader object lock to protect against multiple threads
626 // defining the class in parallel by accident.
627 // This lock must be acquired here so the waiter will find
628 // any successful result in the SystemDictionary and not attempt
629 // the define.
630 // ParallelCapable class loaders and the bootstrap classloader
631 // do not acquire lock here.
632 Handle lockObject = get_loader_lock_or_null(class_loader);
633 ObjectLocker ol(lockObject, THREAD);
634
635 bool circularity_detection_in_progress = false;
636 InstanceKlass* loaded_class = nullptr;
637 SymbolHandle superclassname; // Keep alive while loading in parallel thread.
638
639 guarantee(THREAD->can_call_java(),
640 "can not load classes with compiler thread: class=%s, classloader=%s",
641 name->as_C_string(),
642 class_loader.is_null() ? "null" : class_loader->klass()->name()->as_C_string());
643
644 // Check again (after locking) if the class already exists in SystemDictionary
645 {
646 MutexLocker mu(THREAD, SystemDictionary_lock);
647 InstanceKlass* check = dictionary->find_class(THREAD, name);
648 if (check != nullptr) {
649 // InstanceKlass is already loaded, but we still need to check protection domain below.
650 loaded_class = check;
651 } else {
652 PlaceholderEntry* placeholder = PlaceholderTable::get_entry(name, loader_data);
653 if (placeholder != nullptr && placeholder->circularity_detection_in_progress()) {
654 circularity_detection_in_progress = true;
655 superclassname = placeholder->next_klass_name();
656 assert(superclassname != nullptr, "superclass has to have a name");
657 }
658 }
659 }
660
661 // If the class is in the placeholder table with super_class set,
662 // handle superclass loading in progress.
663 if (circularity_detection_in_progress) {
664 handle_parallel_super_load(name, superclassname,
665 class_loader,
666 protection_domain,
667 CHECK_NULL);
668 }
669
670 bool throw_circularity_error = false;
671 if (loaded_class == nullptr) {
672 bool load_placeholder_added = false;
673
674 // Add placeholder entry to record loading instance class
675 // case 1. Bootstrap classloader
676 // This classloader supports parallelism at the classloader level
677 // but only allows a single thread to load a class/classloader pair.
678 // The LOAD_INSTANCE placeholder is the mechanism for mutual exclusion.
679 // case 2. parallelCapable user level classloaders
680 // These class loaders lock a per-class object lock when ClassLoader.loadClass()
681 // is called. A LOAD_INSTANCE placeholder isn't used for mutual exclusion.
682 // case 3. traditional classloaders that rely on the classloader object lock
683 // There should be no need for need for LOAD_INSTANCE for mutual exclusion,
684 // except the LOAD_INSTANCE placeholder is used to detect CCE for -Xcomp.
685 // TODO: should also be used to detect CCE for parallel capable class loaders but it's not.
686 {
687 MutexLocker mu(THREAD, SystemDictionary_lock);
688 if (needs_load_placeholder(class_loader)) {
689 loaded_class = handle_parallel_loading(THREAD,
690 name,
691 loader_data,
692 class_loader.is_null(),
693 &throw_circularity_error);
694 }
695
696 // Recheck if the class has been loaded for all class loader cases and
697 // add a LOAD_INSTANCE placeholder while holding the SystemDictionary_lock.
698 if (!throw_circularity_error && loaded_class == nullptr) {
699 InstanceKlass* check = dictionary->find_class(THREAD, name);
700 if (check != nullptr) {
701 loaded_class = check;
702 } else if (needs_load_placeholder(class_loader)) {
703 // Add the LOAD_INSTANCE token. Threads will wait on loading to complete for this thread.
704 PlaceholderEntry* newprobe = PlaceholderTable::find_and_add(name, loader_data,
705 PlaceholderTable::LOAD_INSTANCE,
706 nullptr,
707 THREAD);
708 load_placeholder_added = true;
709 }
710 }
711 }
712
713 // Must throw error outside of owning lock
714 if (throw_circularity_error) {
715 assert(!HAS_PENDING_EXCEPTION && !load_placeholder_added, "circularity error cleanup");
716 ResourceMark rm(THREAD);
717 THROW_MSG_NULL(vmSymbols::java_lang_ClassCircularityError(), name->as_C_string());
718 }
719
720 // Be careful when modifying this code: once you have run
721 // PlaceholderTable::find_and_add(PlaceholderTable::LOAD_INSTANCE),
722 // you need to find_and_remove it before returning.
723 // So be careful to not exit with a CHECK_ macro between these calls.
724
725 if (loaded_class == nullptr) {
726 // Do actual loading
727 loaded_class = load_instance_class(name, class_loader, THREAD);
728 }
729
730 if (load_placeholder_added) {
731 // clean up placeholder entries for LOAD_INSTANCE success or error
732 // This brackets the SystemDictionary updates for both defining
733 // and initiating loaders
734 MutexLocker mu(THREAD, SystemDictionary_lock);
735 PlaceholderTable::find_and_remove(name, loader_data, PlaceholderTable::LOAD_INSTANCE, THREAD);
736 SystemDictionary_lock->notify_all();
737 }
738 }
739
740 if (HAS_PENDING_EXCEPTION || loaded_class == nullptr) {
741 return nullptr;
742 }
743
744 if (class_load_start_event.should_commit()) {
745 post_class_load_event(&class_load_start_event, loaded_class, loader_data);
746 }
747
748 // Make sure we have the right class in the dictionary
749 DEBUG_ONLY(verify_dictionary_entry(name, loaded_class));
750
751 if (protection_domain() != nullptr) {
752 // A SecurityManager (if installed) may prevent this protection_domain from accessing loaded_class
753 // by throwing a SecurityException.
754 dictionary->check_package_access(loaded_class, class_loader, protection_domain, CHECK_NULL);
755 }
756
757 return loaded_class;
758 }
759
760
761 // This routine does not lock the system dictionary.
762 //
763 // Since readers don't hold a lock, we must make sure that system
764 // dictionary entries are added to in a safe way (all links must
765 // be updated in an MT-safe manner). All entries are removed during class
766 // unloading, when this class loader is no longer referenced.
767 //
768 // Callers should be aware that an entry could be added just after
769 // Dictionary is read here, so the caller will not see
770 // the new entry.
771
772 InstanceKlass* SystemDictionary::find_instance_klass(Thread* current,
773 Symbol* class_name,
774 Handle class_loader,
775 Handle protection_domain) {
776
777 // The result of this call should be consistent with the result
778 // of the call to resolve_instance_class_or_null().
779 // See evaluation 6790209 and 4474172 for more details.
780 oop class_loader_oop = java_lang_ClassLoader::non_reflection_class_loader(class_loader());
781 ClassLoaderData* loader_data = ClassLoaderData::class_loader_data_or_null(class_loader_oop);
782
783 if (loader_data == nullptr) {
784 // If the ClassLoaderData has not been setup,
785 // then the class loader has no entries in the dictionary.
786 return nullptr;
787 }
788
789 Dictionary* dictionary = loader_data->dictionary();
790 return dictionary->find(current, class_name, protection_domain);
791 }
792
793 // Look for a loaded instance or array klass by name. Do not do any loading.
794 // return null in case of error.
795 Klass* SystemDictionary::find_instance_or_array_klass(Thread* current,
796 Symbol* class_name,
797 Handle class_loader,
798 Handle protection_domain) {
799 Klass* k = nullptr;
800 assert(class_name != nullptr, "class name must be non nullptr");
801
802 if (Signature::is_array(class_name)) {
803 // The name refers to an array. Parse the name.
804 // dimension and object_key in FieldArrayInfo are assigned as a
805 // side-effect of this call
806 SignatureStream ss(class_name, false);
807 int ndims = ss.skip_array_prefix(); // skip all '['s
808 BasicType t = ss.type();
809 if (t != T_OBJECT) {
810 k = Universe::typeArrayKlass(t);
811 } else {
812 k = SystemDictionary::find_instance_klass(current, ss.as_symbol(), class_loader, protection_domain);
813 }
814 if (k != nullptr) {
815 k = k->array_klass_or_null(ndims);
816 }
817 } else {
818 k = find_instance_klass(current, class_name, class_loader, protection_domain);
819 }
820 return k;
821 }
822
823 // Note: this method is much like resolve_class_from_stream, but
824 // does not publish the classes in the SystemDictionary.
825 // Handles Lookup.defineClass hidden.
826 InstanceKlass* SystemDictionary::resolve_hidden_class_from_stream(
827 ClassFileStream* st,
828 Symbol* class_name,
829 Handle class_loader,
830 const ClassLoadInfo& cl_info,
831 TRAPS) {
832
833 EventClassLoad class_load_start_event;
834 ClassLoaderData* loader_data;
835
836 // - for hidden classes that are not strong: create a new CLD that has a class holder and
837 // whose loader is the Lookup class's loader.
838 // - for hidden class: add the class to the Lookup class's loader's CLD.
839 assert (cl_info.is_hidden(), "only used for hidden classes");
840 bool create_mirror_cld = !cl_info.is_strong_hidden();
841 loader_data = register_loader(class_loader, create_mirror_cld);
842
843 assert(st != nullptr, "invariant");
844 assert(st->need_verify(), "invariant");
845
846 // Parse stream and create a klass.
847 InstanceKlass* k = KlassFactory::create_from_stream(st,
848 class_name,
849 loader_data,
850 cl_info,
851 CHECK_NULL);
852 assert(k != nullptr, "no klass created");
853
854 // Hidden classes that are not strong must update ClassLoaderData holder
855 // so that they can be unloaded when the mirror is no longer referenced.
856 if (!cl_info.is_strong_hidden()) {
857 k->class_loader_data()->initialize_holder(Handle(THREAD, k->java_mirror()));
858 }
859
860 // Add to class hierarchy, and do possible deoptimizations.
861 k->add_to_hierarchy(THREAD);
862 // But, do not add to dictionary.
863
864 k->link_class(CHECK_NULL);
865
866 // notify jvmti
867 if (JvmtiExport::should_post_class_load()) {
868 JvmtiExport::post_class_load(THREAD, k);
869 }
870 if (class_load_start_event.should_commit()) {
871 post_class_load_event(&class_load_start_event, k, loader_data);
872 }
873
874 return k;
875 }
876
877 // Add a klass to the system from a stream (called by jni_DefineClass and
878 // JVM_DefineClass).
879 // Note: class_name can be null. In that case we do not know the name of
880 // the class until we have parsed the stream.
881 // This function either returns an InstanceKlass or throws an exception. It does
882 // not return null without a pending exception.
883 InstanceKlass* SystemDictionary::resolve_class_from_stream(
884 ClassFileStream* st,
885 Symbol* class_name,
886 Handle class_loader,
887 const ClassLoadInfo& cl_info,
888 TRAPS) {
889
890 HandleMark hm(THREAD);
891
892 ClassLoaderData* loader_data = register_loader(class_loader);
893
894 // Classloaders that support parallelism, e.g. bootstrap classloader,
895 // do not acquire lock here
896 Handle lockObject = get_loader_lock_or_null(class_loader);
897 ObjectLocker ol(lockObject, THREAD);
898
899 // Parse the stream and create a klass.
900 // Note that we do this even though this klass might
901 // already be present in the SystemDictionary, otherwise we would not
902 // throw potential ClassFormatErrors.
903 InstanceKlass* k = nullptr;
904
905 #if INCLUDE_CDS
906 if (!CDSConfig::is_dumping_static_archive()) {
907 k = SystemDictionaryShared::lookup_from_stream(class_name,
908 class_loader,
909 cl_info.protection_domain(),
910 st,
911 CHECK_NULL);
912 }
913 #endif
914
915 if (k == nullptr) {
916 k = KlassFactory::create_from_stream(st, class_name, loader_data, cl_info, CHECK_NULL);
917 }
918
919 assert(k != nullptr, "no klass created");
920 Symbol* h_name = k->name();
921 assert(class_name == nullptr || class_name == h_name, "name mismatch");
922
923 // Add class just loaded
924 // If a class loader supports parallel classloading, handle parallel define requests.
925 // find_or_define_instance_class may return a different InstanceKlass,
926 // in which case the old k would be deallocated
927 if (is_parallelCapable(class_loader)) {
928 k = find_or_define_instance_class(h_name, class_loader, k, CHECK_NULL);
929 } else {
930 define_instance_class(k, class_loader, THREAD);
931
932 // If defining the class throws an exception register 'k' for cleanup.
933 if (HAS_PENDING_EXCEPTION) {
934 assert(k != nullptr, "Must have an instance klass here!");
935 loader_data->add_to_deallocate_list(k);
936 return nullptr;
937 }
938 }
939
940 // Make sure we have an entry in the SystemDictionary on success
941 DEBUG_ONLY(verify_dictionary_entry(h_name, k));
942
943 return k;
944 }
945
946 InstanceKlass* SystemDictionary::resolve_from_stream(ClassFileStream* st,
947 Symbol* class_name,
948 Handle class_loader,
949 const ClassLoadInfo& cl_info,
950 TRAPS) {
951 if (cl_info.is_hidden()) {
952 return resolve_hidden_class_from_stream(st, class_name, class_loader, cl_info, CHECK_NULL);
953 } else {
954 return resolve_class_from_stream(st, class_name, class_loader, cl_info, CHECK_NULL);
955 }
956 }
957
958
959 #if INCLUDE_CDS
960 // Check if a shared class can be loaded by the specific classloader.
961 bool SystemDictionary::is_shared_class_visible(Symbol* class_name,
962 InstanceKlass* ik,
963 PackageEntry* pkg_entry,
964 Handle class_loader) {
965 assert(!ModuleEntryTable::javabase_moduleEntry()->is_patched(),
966 "Cannot use sharing if java.base is patched");
967
968 // (1) Check if we are loading into the same loader as in dump time.
969
970 if (ik->is_shared_boot_class()) {
971 if (class_loader() != nullptr) {
972 return false;
973 }
974 } else if (ik->is_shared_platform_class()) {
975 if (class_loader() != java_platform_loader()) {
976 return false;
977 }
978 } else if (ik->is_shared_app_class()) {
979 if (class_loader() != java_system_loader()) {
980 return false;
981 }
982 } else {
983 // ik was loaded by a custom loader during dump time
984 if (class_loader_data(class_loader)->is_builtin_class_loader_data()) {
985 return false;
986 } else {
987 return true;
988 }
989 }
990
991 // (2) Check if we are loading into the same module from the same location as in dump time.
992
993 if (CDSConfig::is_using_optimized_module_handling()) {
994 // Class visibility has not changed between dump time and run time, so a class
995 // that was visible (and thus archived) during dump time is always visible during runtime.
996 assert(SystemDictionary::is_shared_class_visible_impl(class_name, ik, pkg_entry, class_loader),
997 "visibility cannot change between dump time and runtime");
998 return true;
999 }
1000 return is_shared_class_visible_impl(class_name, ik, pkg_entry, class_loader);
1001 }
1002
1003 bool SystemDictionary::is_shared_class_visible_impl(Symbol* class_name,
1004 InstanceKlass* ik,
1005 PackageEntry* pkg_entry,
1006 Handle class_loader) {
1007 int scp_index = ik->shared_classpath_index();
1008 assert(!ik->is_shared_unregistered_class(), "this function should be called for built-in classes only");
1009 assert(scp_index >= 0, "must be");
1010 SharedClassPathEntry* scp_entry = FileMapInfo::shared_path(scp_index);
1011 if (!Universe::is_module_initialized()) {
1012 assert(scp_entry != nullptr, "must be");
1013 // At this point, no modules have been defined yet. KlassSubGraphInfo::check_allowed_klass()
1014 // has restricted the classes can be loaded at this step to be only:
1015 // [1] scp_entry->is_modules_image(): classes in java.base, or,
1016 // [2] HeapShared::is_a_test_class_in_unnamed_module(ik): classes in bootstrap/unnamed module
1017 assert(scp_entry->is_modules_image() || HeapShared::is_a_test_class_in_unnamed_module(ik),
1018 "only these classes can be loaded before the module system is initialized");
1019 assert(class_loader.is_null(), "sanity");
1020 return true;
1021 }
1022
1023 if (pkg_entry == nullptr) {
1024 // We might have looked up pkg_entry before the module system was initialized.
1025 // Need to reload it now.
1026 TempNewSymbol pkg_name = ClassLoader::package_from_class_name(class_name);
1027 if (pkg_name != nullptr) {
1028 pkg_entry = class_loader_data(class_loader)->packages()->lookup_only(pkg_name);
1029 }
1030 }
1031
1032 ModuleEntry* mod_entry = (pkg_entry == nullptr) ? nullptr : pkg_entry->module();
1033 bool should_be_in_named_module = (mod_entry != nullptr && mod_entry->is_named());
1034 bool was_archived_from_named_module = scp_entry->in_named_module();
1035 bool visible;
1036
1037 if (mod_entry != nullptr && mod_entry->location() == nullptr && mod_entry->is_named()) {
1038 // Archived module for dynamic proxies. It's always visible.
1039 assert(Modules::is_dynamic_proxy_module(mod_entry), "must be");
1040 visible = true;
1041 } else if (was_archived_from_named_module) {
1042 if (should_be_in_named_module) {
1043 // Is the module loaded from the same location as during dump time?
1044 visible = mod_entry->shared_path_index() == scp_index;
1045 if (visible) {
1046 assert(!mod_entry->is_patched(), "cannot load archived classes for patched module");
1047 }
1048 } else {
1049 // During dump time, this class was in a named module, but at run time, this class should be
1050 // in an unnamed module.
1051 visible = false;
1052 }
1053 } else {
1054 if (should_be_in_named_module) {
1055 // During dump time, this class was in an unnamed, but at run time, this class should be
1056 // in a named module.
1057 visible = false;
1058 } else {
1059 visible = true;
1060 }
1061 }
1062
1063 return visible;
1064 }
1065
1066 bool SystemDictionary::check_shared_class_super_type(InstanceKlass* klass, InstanceKlass* super_type,
1067 Handle class_loader, Handle protection_domain,
1068 bool is_superclass, TRAPS) {
1069 assert(super_type->is_shared(), "must be");
1070
1071 // Quick check if the super type has been already loaded.
1072 // + Don't do it for unregistered classes -- they can be unloaded so
1073 // super_type->class_loader_data() could be stale.
1074 // + Don't check if loader data is null, ie. the super_type isn't fully loaded.
1075 if (!super_type->is_shared_unregistered_class() && super_type->class_loader_data() != nullptr) {
1076 // Check if the superclass is loaded by the current class_loader
1077 Symbol* name = super_type->name();
1078 InstanceKlass* check = find_instance_klass(THREAD, name, class_loader, protection_domain);
1079 if (check == super_type) {
1080 return true;
1081 }
1082 }
1083
1084 Klass *found = resolve_with_circularity_detection(klass->name(), super_type->name(),
1085 class_loader, protection_domain, is_superclass, CHECK_false);
1086 if (found == super_type) {
1087 return true;
1088 } else {
1089 // The dynamically resolved super type is not the same as the one we used during dump time,
1090 // so we cannot use the class.
1091 return false;
1092 }
1093 }
1094
1095 bool SystemDictionary::check_shared_class_super_types(InstanceKlass* ik, Handle class_loader,
1096 Handle protection_domain, TRAPS) {
1097 // Check the superclass and interfaces. They must be the same
1098 // as in dump time, because the layout of <ik> depends on
1099 // the specific layout of ik->super() and ik->local_interfaces().
1100 //
1101 // If unexpected superclass or interfaces are found, we cannot
1102 // load <ik> from the shared archive.
1103
1104 if (ik->super() != nullptr) {
1105 bool check_super = check_shared_class_super_type(ik, InstanceKlass::cast(ik->super()),
1106 class_loader, protection_domain, true,
1107 CHECK_false);
1108 if (!check_super) {
1109 return false;
1110 }
1111 }
1112
1113 Array<InstanceKlass*>* interfaces = ik->local_interfaces();
1114 int num_interfaces = interfaces->length();
1115 for (int index = 0; index < num_interfaces; index++) {
1116 bool check_interface = check_shared_class_super_type(ik, interfaces->at(index), class_loader, protection_domain, false,
1117 CHECK_false);
1118 if (!check_interface) {
1119 return false;
1120 }
1121 }
1122
1123 return true;
1124 }
1125
1126 InstanceKlass* SystemDictionary::load_shared_lambda_proxy_class(InstanceKlass* ik,
1127 Handle class_loader,
1128 Handle protection_domain,
1129 PackageEntry* pkg_entry,
1130 TRAPS) {
1131 InstanceKlass* shared_nest_host = SystemDictionaryShared::get_shared_nest_host(ik);
1132 assert(shared_nest_host->is_shared(), "nest host must be in CDS archive");
1133 Symbol* cn = shared_nest_host->name();
1134 Klass *s = resolve_or_fail(cn, class_loader, protection_domain, true, CHECK_NULL);
1135 if (s != shared_nest_host) {
1136 // The dynamically resolved nest_host is not the same as the one we used during dump time,
1137 // so we cannot use ik.
1138 return nullptr;
1139 } else {
1140 assert(s->is_shared(), "must be");
1141 }
1142
1143 InstanceKlass* loaded_ik = load_shared_class(ik, class_loader, protection_domain, nullptr, pkg_entry, CHECK_NULL);
1144
1145 if (loaded_ik != nullptr) {
1146 assert(shared_nest_host->is_same_class_package(ik),
1147 "lambda proxy class and its nest host must be in the same package");
1148 // The lambda proxy class and its nest host have the same class loader and class loader data,
1149 // as verified in SystemDictionaryShared::add_lambda_proxy_class()
1150 assert(shared_nest_host->class_loader() == class_loader(), "mismatched class loader");
1151 assert(shared_nest_host->class_loader_data() == class_loader_data(class_loader), "mismatched class loader data");
1152 ik->set_nest_host(shared_nest_host);
1153 }
1154
1155 return loaded_ik;
1156 }
1157
1158 InstanceKlass* SystemDictionary::load_shared_class(InstanceKlass* ik,
1159 Handle class_loader,
1160 Handle protection_domain,
1161 const ClassFileStream *cfs,
1162 PackageEntry* pkg_entry,
1163 TRAPS) {
1164 assert(ik != nullptr, "sanity");
1165 assert(!ik->is_unshareable_info_restored(), "shared class can be restored only once");
1166 assert(Atomic::add(&ik->_shared_class_load_count, 1) == 1, "shared class loaded more than once");
1167 Symbol* class_name = ik->name();
1168
1169 if (!is_shared_class_visible(class_name, ik, pkg_entry, class_loader)) {
1170 ik->set_shared_loading_failed();
1171 return nullptr;
1172 }
1173
1174 bool check = check_shared_class_super_types(ik, class_loader, protection_domain, CHECK_NULL);
1175 if (!check) {
1176 ik->set_shared_loading_failed();
1177 return nullptr;
1178 }
1179
1180 InstanceKlass* new_ik = nullptr;
1181 // CFLH check is skipped for VM hidden classes (see KlassFactory::create_from_stream).
1182 // It will be skipped for shared VM hidden lambda proxy classes.
1183 if (!SystemDictionaryShared::is_hidden_lambda_proxy(ik)) {
1184 new_ik = KlassFactory::check_shared_class_file_load_hook(
1185 ik, class_name, class_loader, protection_domain, cfs, CHECK_NULL);
1186 }
1187 if (new_ik != nullptr) {
1188 // The class is changed by CFLH. Return the new class. The shared class is
1189 // not used.
1190 return new_ik;
1191 }
1192
1193 // Adjust methods to recover missing data. They need addresses for
1194 // interpreter entry points and their default native method address
1195 // must be reset.
1196
1197 // Shared classes are all currently loaded by either the bootstrap or
1198 // internal parallel class loaders, so this will never cause a deadlock
1199 // on a custom class loader lock.
1200 // Since this class is already locked with parallel capable class
1201 // loaders, including the bootstrap loader via the placeholder table,
1202 // this lock is currently a nop.
1203
1204 ClassLoaderData* loader_data = class_loader_data(class_loader);
1205 {
1206 HandleMark hm(THREAD);
1207 Handle lockObject = get_loader_lock_or_null(class_loader);
1208 ObjectLocker ol(lockObject, THREAD);
1209 // prohibited package check assumes all classes loaded from archive call
1210 // restore_unshareable_info which calls ik->set_package()
1211 ik->restore_unshareable_info(loader_data, protection_domain, pkg_entry, CHECK_NULL);
1212 }
1213
1214 load_shared_class_misc(ik, loader_data);
1215 return ik;
1216 }
1217
1218 void SystemDictionary::load_shared_class_misc(InstanceKlass* ik, ClassLoaderData* loader_data) {
1219 ik->print_class_load_logging(loader_data, nullptr, nullptr);
1220
1221 // For boot loader, ensure that GetSystemPackage knows that a class in this
1222 // package was loaded.
1223 if (loader_data->is_the_null_class_loader_data()) {
1224 s2 path_index = ik->shared_classpath_index();
1225 if (path_index >= 0) { // FIXME ... for lambda form classes
1226 ik->set_classpath_index(path_index);
1227
1228 if (CDSConfig::is_dumping_final_static_archive()) {
1229 if (path_index > ClassLoaderExt::max_used_path_index()) {
1230 ClassLoaderExt::set_max_used_path_index(path_index);
1231 }
1232 }
1233 }
1234 }
1235
1236 // notify a class loaded from shared object
1237 ClassLoadingService::notify_class_loaded(ik, true /* shared class */);
1238
1239 if (CDSConfig::is_dumping_final_static_archive()) {
1240 SystemDictionaryShared::init_dumptime_info(ik);
1241 if (SystemDictionary::is_platform_class_loader(loader_data->class_loader())) {
1242 ClassLoaderExt::set_has_platform_classes();
1243 } else if (SystemDictionary::is_system_class_loader(loader_data->class_loader())) {
1244 ClassLoaderExt::set_has_app_classes();
1245 }
1246 }
1247 }
1248
1249 #endif // INCLUDE_CDS
1250
1251 InstanceKlass* SystemDictionary::load_instance_class_impl(Symbol* class_name, Handle class_loader, TRAPS) {
1252
1253 if (class_loader.is_null()) {
1254 ResourceMark rm(THREAD);
1255 PackageEntry* pkg_entry = nullptr;
1256 bool search_only_bootloader_append = false;
1257
1258 // Find the package in the boot loader's package entry table.
1259 TempNewSymbol pkg_name = ClassLoader::package_from_class_name(class_name);
1260 if (pkg_name != nullptr) {
1261 pkg_entry = class_loader_data(class_loader)->packages()->lookup_only(pkg_name);
1262 }
1263
1264 // Prior to attempting to load the class, enforce the boot loader's
1265 // visibility boundaries.
1266 if (!Universe::is_module_initialized()) {
1267 // During bootstrapping, prior to module initialization, any
1268 // class attempting to be loaded must be checked against the
1269 // java.base packages in the boot loader's PackageEntryTable.
1270 // No class outside of java.base is allowed to be loaded during
1271 // this bootstrapping window.
1272 if (pkg_entry == nullptr || pkg_entry->in_unnamed_module()) {
1273 // Class is either in the unnamed package or in
1274 // a named package within the unnamed module. Either
1275 // case is outside of java.base, do not attempt to
1276 // load the class post java.base definition. If
1277 // java.base has not been defined, let the class load
1278 // and its package will be checked later by
1279 // ModuleEntryTable::verify_javabase_packages.
1280 if (ModuleEntryTable::javabase_defined()) {
1281 return nullptr;
1282 }
1283 } else {
1284 // Check that the class' package is defined within java.base.
1285 ModuleEntry* mod_entry = pkg_entry->module();
1286 Symbol* mod_entry_name = mod_entry->name();
1287 if (mod_entry_name->fast_compare(vmSymbols::java_base()) != 0) {
1288 return nullptr;
1289 }
1290 }
1291 } else {
1292 // After the module system has been initialized, check if the class'
1293 // package is in a module defined to the boot loader.
1294 if (pkg_name == nullptr || pkg_entry == nullptr || pkg_entry->in_unnamed_module()) {
1295 // Class is either in the unnamed package, in a named package
1296 // within a module not defined to the boot loader or in a
1297 // a named package within the unnamed module. In all cases,
1298 // limit visibility to search for the class only in the boot
1299 // loader's append path.
1300 if (!ClassLoader::has_bootclasspath_append()) {
1301 // If there is no bootclasspath append entry, no need to continue
1302 // searching.
1303 return nullptr;
1304 }
1305 search_only_bootloader_append = true;
1306 }
1307 }
1308
1309 // Prior to bootstrapping's module initialization, never load a class outside
1310 // of the boot loader's module path
1311 assert(Universe::is_module_initialized() ||
1312 !search_only_bootloader_append,
1313 "Attempt to load a class outside of boot loader's module path");
1314
1315 // Search for classes in the CDS archive.
1316 InstanceKlass* k = nullptr;
1317
1318 #if INCLUDE_CDS
1319 if (CDSConfig::is_using_archive())
1320 {
1321 PerfTraceElapsedTime vmtimer(ClassLoader::perf_shared_classload_time());
1322 InstanceKlass* ik = SystemDictionaryShared::find_builtin_class(class_name);
1323 if (ik != nullptr && ik->is_shared_boot_class() && !ik->shared_loading_failed()) {
1324 SharedClassLoadingMark slm(THREAD, ik);
1325 k = load_shared_class(ik, class_loader, Handle(), nullptr, pkg_entry, CHECK_NULL);
1326 }
1327 }
1328 #endif
1329
1330 if (k == nullptr) {
1331 // Use VM class loader
1332 PerfTraceElapsedTime vmtimer(ClassLoader::perf_sys_classload_time());
1333 k = ClassLoader::load_class(class_name, pkg_entry, search_only_bootloader_append, CHECK_NULL);
1334 }
1335
1336 // find_or_define_instance_class may return a different InstanceKlass
1337 if (k != nullptr) {
1338 CDS_ONLY(SharedClassLoadingMark slm(THREAD, k);)
1339 k = find_or_define_instance_class(class_name, class_loader, k, CHECK_NULL);
1340 }
1341 return k;
1342 } else {
1343 // Use user specified class loader to load class. Call loadClass operation on class_loader.
1344 ResourceMark rm(THREAD);
1345
1346 JavaThread* jt = THREAD;
1347
1348 PerfClassTraceTime vmtimer(ClassLoader::perf_app_classload_time(),
1349 ClassLoader::perf_app_classload_selftime(),
1350 ClassLoader::perf_app_classload_count(),
1351 jt->get_thread_stat()->perf_recursion_counts_addr(),
1352 jt->get_thread_stat()->perf_timers_addr(),
1353 PerfClassTraceTime::CLASS_LOAD);
1354
1355 // Translate to external class name format, i.e., convert '/' chars to '.'
1356 Handle string = java_lang_String::externalize_classname(class_name, CHECK_NULL);
1357
1358 JavaValue result(T_OBJECT);
1359
1360 InstanceKlass* spec_klass = vmClasses::ClassLoader_klass();
1361
1362 // Call public unsynchronized loadClass(String) directly for all class loaders.
1363 // For parallelCapable class loaders, JDK >=7, loadClass(String, boolean) will
1364 // acquire a class-name based lock rather than the class loader object lock.
1365 // JDK < 7 already acquire the class loader lock in loadClass(String, boolean).
1366 JavaCalls::call_virtual(&result,
1367 class_loader,
1368 spec_klass,
1369 vmSymbols::loadClass_name(),
1370 vmSymbols::string_class_signature(),
1371 string,
1372 CHECK_NULL);
1373
1374 assert(result.get_type() == T_OBJECT, "just checking");
1375 oop obj = result.get_oop();
1376
1377 // Primitive classes return null since forName() can not be
1378 // used to obtain any of the Class objects representing primitives or void
1379 if ((obj != nullptr) && !(java_lang_Class::is_primitive(obj))) {
1380 InstanceKlass* k = InstanceKlass::cast(java_lang_Class::as_Klass(obj));
1381 // For user defined Java class loaders, check that the name returned is
1382 // the same as that requested. This check is done for the bootstrap
1383 // loader when parsing the class file.
1384 if (class_name == k->name()) {
1385 return k;
1386 }
1387 }
1388 // Class is not found or has the wrong name, return null
1389 return nullptr;
1390 }
1391 }
1392
1393 InstanceKlass* SystemDictionary::load_instance_class(Symbol* name,
1394 Handle class_loader,
1395 TRAPS) {
1396
1397 InstanceKlass* loaded_class = load_instance_class_impl(name, class_loader, CHECK_NULL);
1398
1399 // If everything was OK (no exceptions, no null return value), and
1400 // class_loader is NOT the defining loader, do a little more bookkeeping.
1401 if (loaded_class != nullptr &&
1402 loaded_class->class_loader() != class_loader()) {
1403
1404 ClassLoaderData* loader_data = class_loader_data(class_loader);
1405 check_constraints(loaded_class, loader_data, false, CHECK_NULL);
1406
1407 // Record dependency for non-parent delegation.
1408 // This recording keeps the defining class loader of the klass (loaded_class) found
1409 // from being unloaded while the initiating class loader is loaded
1410 // even if the reference to the defining class loader is dropped
1411 // before references to the initiating class loader.
1412 loader_data->record_dependency(loaded_class);
1413
1414 update_dictionary(THREAD, loaded_class, loader_data);
1415
1416 if (JvmtiExport::should_post_class_load()) {
1417 JvmtiExport::post_class_load(THREAD, loaded_class);
1418 }
1419 }
1420 return loaded_class;
1421 }
1422
1423 static void post_class_define_event(InstanceKlass* k, const ClassLoaderData* def_cld) {
1424 EventClassDefine event;
1425 if (event.should_commit()) {
1426 event.set_definedClass(k);
1427 event.set_definingClassLoader(def_cld);
1428 event.commit();
1429 }
1430 }
1431
1432 void SystemDictionary::define_instance_class(InstanceKlass* k, Handle class_loader, TRAPS) {
1433
1434 ClassLoaderData* loader_data = k->class_loader_data();
1435 assert(loader_data->class_loader() == class_loader(), "they must be the same");
1436
1437 // Bootstrap and other parallel classloaders don't acquire a lock,
1438 // they use placeholder token.
1439 // If a parallelCapable class loader calls define_instance_class instead of
1440 // find_or_define_instance_class to get here, we have a timing
1441 // hole with systemDictionary updates and check_constraints
1442 if (!is_parallelCapable(class_loader)) {
1443 assert(ObjectSynchronizer::current_thread_holds_lock(THREAD,
1444 get_loader_lock_or_null(class_loader)),
1445 "define called without lock");
1446 }
1447
1448 // Check class-loading constraints. Throw exception if violation is detected.
1449 // Grabs and releases SystemDictionary_lock
1450 // The check_constraints/find_class call and update_dictionary sequence
1451 // must be "atomic" for a specific class/classloader pair so we never
1452 // define two different instanceKlasses for that class/classloader pair.
1453 // Existing classloaders will call define_instance_class with the
1454 // classloader lock held
1455 // Parallel classloaders will call find_or_define_instance_class
1456 // which will require a token to perform the define class
1457 check_constraints(k, loader_data, true, CHECK);
1458
1459 // Register class just loaded with class loader (placed in ArrayList)
1460 // Note we do this before updating the dictionary, as this can
1461 // fail with an OutOfMemoryError (if it does, we will *not* put this
1462 // class in the dictionary and will not update the class hierarchy).
1463 // JVMTI FollowReferences needs to find the classes this way.
1464 if (k->class_loader() != nullptr) {
1465 methodHandle m(THREAD, Universe::loader_addClass_method());
1466 JavaValue result(T_VOID);
1467 JavaCallArguments args(class_loader);
1468 args.push_oop(Handle(THREAD, k->java_mirror()));
1469 JavaCalls::call(&result, m, &args, CHECK);
1470 }
1471
1472 // Add to class hierarchy, and do possible deoptimizations.
1473 k->add_to_hierarchy(THREAD);
1474
1475 // Add to systemDictionary - so other classes can see it.
1476 // Grabs and releases SystemDictionary_lock
1477 update_dictionary(THREAD, k, loader_data);
1478
1479 // notify jvmti
1480 if (JvmtiExport::should_post_class_load()) {
1481 JvmtiExport::post_class_load(THREAD, k);
1482 }
1483 post_class_define_event(k, loader_data);
1484 }
1485
1486 // Support parallel classloading
1487 // All parallel class loaders, including bootstrap classloader
1488 // lock a placeholder entry for this class/class_loader pair
1489 // to allow parallel defines of different classes for this class loader
1490 // With AllowParallelDefine flag==true, in case they do not synchronize around
1491 // FindLoadedClass/DefineClass, calls, we check for parallel
1492 // loading for them, wait if a defineClass is in progress
1493 // and return the initial requestor's results
1494 // This flag does not apply to the bootstrap classloader.
1495 // With AllowParallelDefine flag==false, call through to define_instance_class
1496 // which will throw LinkageError: duplicate class definition.
1497 // False is the requested default.
1498 // For better performance, the class loaders should synchronize
1499 // findClass(), i.e. FindLoadedClass/DefineClassIfAbsent or they
1500 // potentially waste time reading and parsing the bytestream.
1501 // Note: VM callers should ensure consistency of k/class_name,class_loader
1502 // Be careful when modifying this code: once you have run
1503 // PlaceholderTable::find_and_add(PlaceholderTable::DEFINE_CLASS),
1504 // you need to find_and_remove it before returning.
1505 // So be careful to not exit with a CHECK_ macro between these calls.
1506 InstanceKlass* SystemDictionary::find_or_define_helper(Symbol* class_name, Handle class_loader,
1507 InstanceKlass* k, TRAPS) {
1508
1509 Symbol* name_h = k->name();
1510 ClassLoaderData* loader_data = class_loader_data(class_loader);
1511 Dictionary* dictionary = loader_data->dictionary();
1512
1513 // Hold SD lock around find_class and placeholder creation for DEFINE_CLASS
1514 {
1515 MutexLocker mu(THREAD, SystemDictionary_lock);
1516 // First check if class already defined
1517 if (is_parallelDefine(class_loader)) {
1518 InstanceKlass* check = dictionary->find_class(THREAD, name_h);
1519 if (check != nullptr) {
1520 return check;
1521 }
1522 }
1523
1524 // Acquire define token for this class/classloader
1525 PlaceholderEntry* probe = PlaceholderTable::find_and_add(name_h, loader_data,
1526 PlaceholderTable::DEFINE_CLASS, nullptr, THREAD);
1527 // Wait if another thread defining in parallel
1528 // All threads wait - even those that will throw duplicate class: otherwise
1529 // caller is surprised by LinkageError: duplicate, but findLoadedClass fails
1530 // if other thread has not finished updating dictionary
1531 while (probe->definer() != nullptr) {
1532 SystemDictionary_lock->wait();
1533 }
1534 // Only special cases allow parallel defines and can use other thread's results
1535 // Other cases fall through, and may run into duplicate defines
1536 // caught by finding an entry in the SystemDictionary
1537 if (is_parallelDefine(class_loader) && (probe->instance_klass() != nullptr)) {
1538 InstanceKlass* ik = probe->instance_klass();
1539 PlaceholderTable::find_and_remove(name_h, loader_data, PlaceholderTable::DEFINE_CLASS, THREAD);
1540 SystemDictionary_lock->notify_all();
1541 #ifdef ASSERT
1542 InstanceKlass* check = dictionary->find_class(THREAD, name_h);
1543 assert(check != nullptr, "definer missed recording success");
1544 #endif
1545 return ik;
1546 } else {
1547 // This thread will define the class (even if earlier thread tried and had an error)
1548 probe->set_definer(THREAD);
1549 }
1550 }
1551
1552 define_instance_class(k, class_loader, THREAD);
1553
1554 // definer must notify any waiting threads
1555 {
1556 MutexLocker mu(THREAD, SystemDictionary_lock);
1557 PlaceholderEntry* probe = PlaceholderTable::get_entry(name_h, loader_data);
1558 assert(probe != nullptr, "DEFINE_CLASS placeholder lost?");
1559 if (!HAS_PENDING_EXCEPTION) {
1560 probe->set_instance_klass(k);
1561 }
1562 probe->set_definer(nullptr);
1563 PlaceholderTable::find_and_remove(name_h, loader_data, PlaceholderTable::DEFINE_CLASS, THREAD);
1564 SystemDictionary_lock->notify_all();
1565 }
1566
1567 return HAS_PENDING_EXCEPTION ? nullptr : k;
1568 }
1569
1570 // If a class loader supports parallel classloading handle parallel define requests.
1571 // find_or_define_instance_class may return a different InstanceKlass
1572 InstanceKlass* SystemDictionary::find_or_define_instance_class(Symbol* class_name, Handle class_loader,
1573 InstanceKlass* k, TRAPS) {
1574 InstanceKlass* defined_k = find_or_define_helper(class_name, class_loader, k, THREAD);
1575 // Clean up original InstanceKlass if duplicate or error
1576 if (!HAS_PENDING_EXCEPTION && defined_k != k) {
1577 // If a parallel capable class loader already defined this class, register 'k' for cleanup.
1578 assert(defined_k != nullptr, "Should have a klass if there's no exception");
1579 k->class_loader_data()->add_to_deallocate_list(k);
1580 } else if (HAS_PENDING_EXCEPTION) {
1581 // Remove this InstanceKlass from the LoaderConstraintTable if added.
1582 LoaderConstraintTable::remove_failed_loaded_klass(k, class_loader_data(class_loader));
1583 assert(defined_k == nullptr, "Should not have a klass if there's an exception");
1584 k->class_loader_data()->add_to_deallocate_list(k);
1585 }
1586 return defined_k;
1587 }
1588
1589
1590 // ----------------------------------------------------------------------------
1591 // GC support
1592
1593 // Assumes classes in the SystemDictionary are only unloaded at a safepoint
1594 bool SystemDictionary::do_unloading(GCTimer* gc_timer) {
1595
1596 bool unloading_occurred;
1597 bool is_concurrent = !SafepointSynchronize::is_at_safepoint();
1598 {
1599 GCTraceTime(Debug, gc, phases) t("ClassLoaderData", gc_timer);
1600 assert_locked_or_safepoint(ClassLoaderDataGraph_lock); // caller locks.
1601 // First, mark for unload all ClassLoaderData referencing a dead class loader.
1602 unloading_occurred = ClassLoaderDataGraph::do_unloading();
1603 if (unloading_occurred) {
1604 ConditionalMutexLocker ml2(Module_lock, is_concurrent);
1605 JFR_ONLY(Jfr::on_unloading_classes();)
1606 MANAGEMENT_ONLY(FinalizerService::purge_unloaded();)
1607 ConditionalMutexLocker ml1(SystemDictionary_lock, is_concurrent);
1608 ClassLoaderDataGraph::clean_module_and_package_info();
1609 LoaderConstraintTable::purge_loader_constraints();
1610 ResolutionErrorTable::purge_resolution_errors();
1611 }
1612 }
1613
1614 GCTraceTime(Debug, gc, phases) t("Trigger cleanups", gc_timer);
1615
1616 if (unloading_occurred) {
1617 SymbolTable::trigger_cleanup();
1618
1619 if (java_lang_System::allow_security_manager()) {
1620 // Oops referenced by the protection domain cache table may get unreachable independently
1621 // of the class loader (eg. cached protection domain oops). So we need to
1622 // explicitly unlink them here.
1623 // All protection domain oops are linked to the caller class, so if nothing
1624 // unloads, this is not needed.
1625 ProtectionDomainCacheTable::trigger_cleanup();
1626 } else {
1627 assert(ProtectionDomainCacheTable::number_of_entries() == 0, "should be empty");
1628 }
1629
1630 ConditionalMutexLocker ml(ClassInitError_lock, is_concurrent);
1631 InstanceKlass::clean_initialization_error_table();
1632 }
1633
1634 return unloading_occurred;
1635 }
1636
1637 void SystemDictionary::methods_do(void f(Method*)) {
1638 // Walk methods in loaded classes
1639
1640 {
1641 MutexLocker ml(ClassLoaderDataGraph_lock);
1642 ClassLoaderDataGraph::methods_do(f);
1643 }
1644
1645 auto doit = [&] (InvokeMethodKey key, Method* method) {
1646 if (method != nullptr) {
1647 f(method);
1648 }
1649 };
1650
1651 {
1652 MutexLocker ml(InvokeMethodIntrinsicTable_lock);
1653 _invoke_method_intrinsic_table->iterate_all(doit);
1654 }
1655
1656 }
1657
1658 // ----------------------------------------------------------------------------
1659 // Initialization
1660
1661 void SystemDictionary::initialize(TRAPS) {
1662 _invoke_method_intrinsic_table = new (mtClass) InvokeMethodIntrinsicTable();
1663 _invoke_method_type_table = new (mtClass) InvokeMethodTypeTable();
1664 ResolutionErrorTable::initialize();
1665 LoaderConstraintTable::initialize();
1666 PlaceholderTable::initialize();
1667 ProtectionDomainCacheTable::initialize();
1668 #if INCLUDE_CDS
1669 SystemDictionaryShared::initialize();
1670 #endif
1671 // Resolve basic classes
1672 vmClasses::resolve_all(CHECK);
1673 // Resolve classes used by archived heap objects
1674 if (CDSConfig::is_using_archive()) {
1675 HeapShared::resolve_classes(THREAD);
1676 }
1677 }
1678
1679 // Constraints on class loaders. The details of the algorithm can be
1680 // found in the OOPSLA'98 paper "Dynamic Class Loading in the Java
1681 // Virtual Machine" by Sheng Liang and Gilad Bracha. The basic idea is
1682 // that the dictionary needs to maintain a set of constraints that
1683 // must be satisfied by all classes in the dictionary.
1684 // if defining is true, then LinkageError if already in dictionary
1685 // if initiating loader, then ok if InstanceKlass matches existing entry
1686
1687 void SystemDictionary::check_constraints(InstanceKlass* k,
1688 ClassLoaderData* loader_data,
1689 bool defining,
1690 TRAPS) {
1691 ResourceMark rm(THREAD);
1692 stringStream ss;
1693 bool throwException = false;
1694
1695 {
1696 Symbol* name = k->name();
1697
1698 MutexLocker mu(THREAD, SystemDictionary_lock);
1699
1700 InstanceKlass* check = loader_data->dictionary()->find_class(THREAD, name);
1701 if (check != nullptr) {
1702 // If different InstanceKlass - duplicate class definition,
1703 // else - ok, class loaded by a different thread in parallel.
1704 // We should only have found it if it was done loading and ok to use.
1705
1706 if ((defining == true) || (k != check)) {
1707 throwException = true;
1708 ss.print("loader %s", loader_data->loader_name_and_id());
1709 ss.print(" attempted duplicate %s definition for %s. (%s)",
1710 k->external_kind(), k->external_name(), k->class_in_module_of_loader(false, true));
1711 } else {
1712 return;
1713 }
1714 }
1715
1716 if (throwException == false) {
1717 if (LoaderConstraintTable::check_or_update(k, loader_data, name) == false) {
1718 throwException = true;
1719 ss.print("loader constraint violation: loader %s", loader_data->loader_name_and_id());
1720 ss.print(" wants to load %s %s.",
1721 k->external_kind(), k->external_name());
1722 Klass *existing_klass = LoaderConstraintTable::find_constrained_klass(name, loader_data);
1723 if (existing_klass != nullptr && existing_klass->class_loader_data() != loader_data) {
1724 ss.print(" A different %s with the same name was previously loaded by %s. (%s)",
1725 existing_klass->external_kind(),
1726 existing_klass->class_loader_data()->loader_name_and_id(),
1727 existing_klass->class_in_module_of_loader(false, true));
1728 } else {
1729 ss.print(" (%s)", k->class_in_module_of_loader(false, true));
1730 }
1731 }
1732 }
1733 }
1734
1735 // Throw error now if needed (cannot throw while holding
1736 // SystemDictionary_lock because of rank ordering)
1737 if (throwException == true) {
1738 THROW_MSG(vmSymbols::java_lang_LinkageError(), ss.as_string());
1739 }
1740 }
1741
1742 // Update class loader data dictionary - done after check_constraint and add_to_hierarchy
1743 // have been called.
1744 void SystemDictionary::update_dictionary(JavaThread* current,
1745 InstanceKlass* k,
1746 ClassLoaderData* loader_data) {
1747 MonitorLocker mu1(SystemDictionary_lock);
1748
1749 // Make a new dictionary entry.
1750 Symbol* name = k->name();
1751 Dictionary* dictionary = loader_data->dictionary();
1752 InstanceKlass* sd_check = dictionary->find_class(current, name);
1753 if (sd_check == nullptr) {
1754 dictionary->add_klass(current, name, k);
1755 }
1756 mu1.notify_all();
1757 }
1758
1759 #if INCLUDE_CDS
1760 // Indicate that loader_data has initiated the loading of class k, which
1761 // has already been defined by a parent loader.
1762 // This API should be used only by AOTLinkedClassBulkLoader
1763 void SystemDictionary::add_to_initiating_loader(JavaThread* current,
1764 InstanceKlass* k,
1765 ClassLoaderData* loader_data) {
1766 assert(CDSConfig::is_using_aot_linked_classes(), "must be");
1767 assert_locked_or_safepoint(SystemDictionary_lock);
1768 Symbol* name = k->name();
1769 Dictionary* dictionary = loader_data->dictionary();
1770 assert(k->is_loaded(), "must be");
1771 assert(k->class_loader_data() != loader_data, "only for classes defined by a parent loader");
1772 assert(dictionary->find_class(current, name) == nullptr, "sanity");
1773 dictionary->add_klass(current, name, k);
1774 }
1775 #endif
1776
1777 // Try to find a class name using the loader constraints. The
1778 // loader constraints might know about a class that isn't fully loaded
1779 // yet and these will be ignored.
1780 Klass* SystemDictionary::find_constrained_instance_or_array_klass(
1781 Thread* current, Symbol* class_name, Handle class_loader) {
1782
1783 // First see if it has been loaded directly.
1784 // Force the protection domain to be null. (This removes protection checks.)
1785 Handle no_protection_domain;
1786 Klass* klass = find_instance_or_array_klass(current, class_name, class_loader,
1787 no_protection_domain);
1788 if (klass != nullptr)
1789 return klass;
1790
1791 // Now look to see if it has been loaded elsewhere, and is subject to
1792 // a loader constraint that would require this loader to return the
1793 // klass that is already loaded.
1794 if (Signature::is_array(class_name)) {
1795 // For array classes, their Klass*s are not kept in the
1796 // constraint table. The element Klass*s are.
1797 SignatureStream ss(class_name, false);
1798 int ndims = ss.skip_array_prefix(); // skip all '['s
1799 BasicType t = ss.type();
1800 if (t != T_OBJECT) {
1801 klass = Universe::typeArrayKlass(t);
1802 } else {
1803 MutexLocker mu(current, SystemDictionary_lock);
1804 klass = LoaderConstraintTable::find_constrained_klass(ss.as_symbol(), class_loader_data(class_loader));
1805 }
1806 // If element class already loaded, allocate array klass
1807 if (klass != nullptr) {
1808 klass = klass->array_klass_or_null(ndims);
1809 }
1810 } else {
1811 MutexLocker mu(current, SystemDictionary_lock);
1812 // Non-array classes are easy: simply check the constraint table.
1813 klass = LoaderConstraintTable::find_constrained_klass(class_name, class_loader_data(class_loader));
1814 }
1815
1816 return klass;
1817 }
1818
1819 bool SystemDictionary::add_loader_constraint(Symbol* class_name,
1820 Klass* klass_being_linked,
1821 Handle class_loader1,
1822 Handle class_loader2) {
1823 ClassLoaderData* loader_data1 = class_loader_data(class_loader1);
1824 ClassLoaderData* loader_data2 = class_loader_data(class_loader2);
1825
1826 Symbol* constraint_name = nullptr;
1827
1828 if (!Signature::is_array(class_name)) {
1829 constraint_name = class_name;
1830 } else {
1831 // For array classes, their Klass*s are not kept in the
1832 // constraint table. The element classes are.
1833 SignatureStream ss(class_name, false);
1834 ss.skip_array_prefix(); // skip all '['s
1835 if (!ss.has_envelope()) {
1836 return true; // primitive types always pass
1837 }
1838 constraint_name = ss.as_symbol();
1839 // Increment refcount to keep constraint_name alive after
1840 // SignatureStream is destructed. It will be decremented below
1841 // before returning.
1842 constraint_name->increment_refcount();
1843 }
1844
1845 Dictionary* dictionary1 = loader_data1->dictionary();
1846 Dictionary* dictionary2 = loader_data2->dictionary();
1847
1848 JavaThread* current = JavaThread::current();
1849 {
1850 MutexLocker mu_s(SystemDictionary_lock);
1851 InstanceKlass* klass1 = dictionary1->find_class(current, constraint_name);
1852 InstanceKlass* klass2 = dictionary2->find_class(current, constraint_name);
1853 bool result = LoaderConstraintTable::add_entry(constraint_name, klass1, loader_data1,
1854 klass2, loader_data2);
1855 #if INCLUDE_CDS
1856 if (CDSConfig::is_dumping_archive() && klass_being_linked != nullptr &&
1857 !klass_being_linked->is_shared()) {
1858 SystemDictionaryShared::record_linking_constraint(constraint_name,
1859 InstanceKlass::cast(klass_being_linked),
1860 class_loader1, class_loader2);
1861 }
1862 #endif // INCLUDE_CDS
1863 if (Signature::is_array(class_name)) {
1864 constraint_name->decrement_refcount();
1865 }
1866 return result;
1867 }
1868 }
1869
1870 // Add entry to resolution error table to record the error when the first
1871 // attempt to resolve a reference to a class has failed.
1872 void SystemDictionary::add_resolution_error(const constantPoolHandle& pool, int which,
1873 Symbol* error, const char* message,
1874 Symbol* cause, const char* cause_msg) {
1875 {
1876 MutexLocker ml(Thread::current(), SystemDictionary_lock);
1877 ResolutionErrorEntry* entry = ResolutionErrorTable::find_entry(pool, which);
1878 if (entry == nullptr) {
1879 ResolutionErrorTable::add_entry(pool, which, error, message, cause, cause_msg);
1880 }
1881 }
1882 }
1883
1884 // Delete a resolution error for RedefineClasses for a constant pool is going away
1885 void SystemDictionary::delete_resolution_error(ConstantPool* pool) {
1886 ResolutionErrorTable::delete_entry(pool);
1887 }
1888
1889 // Lookup resolution error table. Returns error if found, otherwise null.
1890 Symbol* SystemDictionary::find_resolution_error(const constantPoolHandle& pool, int which,
1891 const char** message,
1892 Symbol** cause, const char** cause_msg) {
1893
1894 {
1895 MutexLocker ml(Thread::current(), SystemDictionary_lock);
1896 ResolutionErrorEntry* entry = ResolutionErrorTable::find_entry(pool, which);
1897 if (entry != nullptr) {
1898 *message = entry->message();
1899 *cause = entry->cause();
1900 *cause_msg = entry->cause_msg();
1901 return entry->error();
1902 } else {
1903 return nullptr;
1904 }
1905 }
1906 }
1907
1908 // Add an entry to resolution error table to record an error in resolving or
1909 // validating a nest host. This is used to construct informative error
1910 // messages when IllegalAccessError's occur. If an entry already exists it will
1911 // be updated with the nest host error message.
1912
1913 void SystemDictionary::add_nest_host_error(const constantPoolHandle& pool,
1914 int which,
1915 const char* message) {
1916 {
1917 MutexLocker ml(Thread::current(), SystemDictionary_lock);
1918 ResolutionErrorEntry* entry = ResolutionErrorTable::find_entry(pool, which);
1919 if (entry != nullptr && entry->nest_host_error() == nullptr) {
1920 // An existing entry means we had a true resolution failure (LinkageError) with our nest host, but we
1921 // still want to add the error message for the higher-level access checks to report. We should
1922 // only reach here under the same error condition, so we can ignore the potential race with setting
1923 // the message. If we see it is already set then we can ignore it.
1924 entry->set_nest_host_error(message);
1925 } else {
1926 ResolutionErrorTable::add_entry(pool, which, message);
1927 }
1928 }
1929 }
1930
1931 // Lookup any nest host error
1932 const char* SystemDictionary::find_nest_host_error(const constantPoolHandle& pool, int which) {
1933 {
1934 MutexLocker ml(Thread::current(), SystemDictionary_lock);
1935 ResolutionErrorEntry* entry = ResolutionErrorTable::find_entry(pool, which);
1936 if (entry != nullptr) {
1937 return entry->nest_host_error();
1938 } else {
1939 return nullptr;
1940 }
1941 }
1942 }
1943
1944 // Signature constraints ensure that callers and callees agree about
1945 // the meaning of type names in their signatures. This routine is the
1946 // intake for constraints. It collects them from several places:
1947 //
1948 // * LinkResolver::resolve_method (if check_access is true) requires
1949 // that the resolving class (the caller) and the defining class of
1950 // the resolved method (the callee) agree on each type in the
1951 // method's signature.
1952 //
1953 // * LinkResolver::resolve_interface_method performs exactly the same
1954 // checks.
1955 //
1956 // * LinkResolver::resolve_field requires that the constant pool
1957 // attempting to link to a field agree with the field's defining
1958 // class about the type of the field signature.
1959 //
1960 // * klassVtable::initialize_vtable requires that, when a class
1961 // overrides a vtable entry allocated by a superclass, that the
1962 // overriding method (i.e., the callee) agree with the superclass
1963 // on each type in the method's signature.
1964 //
1965 // * klassItable::initialize_itable requires that, when a class fills
1966 // in its itables, for each non-abstract method installed in an
1967 // itable, the method (i.e., the callee) agree with the interface
1968 // on each type in the method's signature.
1969 //
1970 // All those methods have a boolean (check_access, checkconstraints)
1971 // which turns off the checks. This is used from specialized contexts
1972 // such as bootstrapping, dumping, and debugging.
1973 //
1974 // No direct constraint is placed between the class and its
1975 // supertypes. Constraints are only placed along linked relations
1976 // between callers and callees. When a method overrides or implements
1977 // an abstract method in a supertype (superclass or interface), the
1978 // constraints are placed as if the supertype were the caller to the
1979 // overriding method. (This works well, since callers to the
1980 // supertype have already established agreement between themselves and
1981 // the supertype.) As a result of all this, a class can disagree with
1982 // its supertype about the meaning of a type name, as long as that
1983 // class neither calls a relevant method of the supertype, nor is
1984 // called (perhaps via an override) from the supertype.
1985 //
1986 //
1987 // SystemDictionary::check_signature_loaders(sig, klass_being_linked, l1, l2)
1988 //
1989 // Make sure all class components (including arrays) in the given
1990 // signature will be resolved to the same class in both loaders.
1991 // Returns the name of the type that failed a loader constraint check, or
1992 // null if no constraint failed. No exception except OOME is thrown.
1993 // Arrays are not added to the loader constraint table, their elements are.
1994 Symbol* SystemDictionary::check_signature_loaders(Symbol* signature,
1995 Klass* klass_being_linked,
1996 Handle loader1, Handle loader2,
1997 bool is_method) {
1998 // Nothing to do if loaders are the same.
1999 if (loader1() == loader2()) {
2000 return nullptr;
2001 }
2002
2003 for (SignatureStream ss(signature, is_method); !ss.is_done(); ss.next()) {
2004 if (ss.is_reference()) {
2005 Symbol* sig = ss.as_symbol();
2006 // Note: In the future, if template-like types can take
2007 // arguments, we will want to recognize them and dig out class
2008 // names hiding inside the argument lists.
2009 if (!add_loader_constraint(sig, klass_being_linked, loader1, loader2)) {
2010 return sig;
2011 }
2012 }
2013 }
2014 return nullptr;
2015 }
2016
2017 Method* SystemDictionary::find_method_handle_intrinsic(vmIntrinsicID iid,
2018 Symbol* signature,
2019 TRAPS) {
2020
2021 const int iid_as_int = vmIntrinsics::as_int(iid);
2022 assert(MethodHandles::is_signature_polymorphic(iid) &&
2023 MethodHandles::is_signature_polymorphic_intrinsic(iid) &&
2024 iid != vmIntrinsics::_invokeGeneric,
2025 "must be a known MH intrinsic iid=%d: %s", iid_as_int, vmIntrinsics::name_at(iid));
2026
2027 InvokeMethodKey key(signature, iid_as_int);
2028 Method** met = nullptr;
2029
2030 // We only want one entry in the table for this (signature/id, method) pair but the code
2031 // to create the intrinsic method needs to be outside the lock.
2032 // The first thread claims the entry by adding the key and the other threads wait, until the
2033 // Method has been added as the value.
2034 {
2035 MonitorLocker ml(THREAD, InvokeMethodIntrinsicTable_lock);
2036 while (true) {
2037 bool created;
2038 met = _invoke_method_intrinsic_table->put_if_absent(key, &created);
2039 assert(met != nullptr, "either created or found");
2040 if (*met != nullptr) {
2041 return *met;
2042 } else if (created) {
2043 // The current thread won the race and will try to create the full entry.
2044 break;
2045 } else {
2046 // Another thread beat us to it, so wait for them to complete
2047 // and return *met; or if they hit an error we get another try.
2048 ml.wait();
2049 // Note it is not safe to read *met here as that entry could have
2050 // been deleted, so we must loop and try put_if_absent again.
2051 }
2052 }
2053 }
2054
2055 methodHandle m = Method::make_method_handle_intrinsic(iid, signature, THREAD);
2056 bool throw_error = HAS_PENDING_EXCEPTION;
2057 if (!throw_error && (!Arguments::is_interpreter_only() || iid == vmIntrinsics::_linkToNative)) {
2058 // Generate a compiled form of the MH intrinsic
2059 // linkToNative doesn't have interpreter-specific implementation, so always has to go through compiled version.
2060 AdapterHandlerLibrary::create_native_wrapper(m);
2061 // Check if have the compiled code.
2062 throw_error = (!m->has_compiled_code());
2063 }
2064
2065 {
2066 MonitorLocker ml(THREAD, InvokeMethodIntrinsicTable_lock);
2067 if (throw_error) {
2068 // Remove the entry and let another thread try, or get the same exception.
2069 bool removed = _invoke_method_intrinsic_table->remove(key);
2070 assert(removed, "must be the owner");
2071 ml.notify_all();
2072 } else {
2073 signature->make_permanent(); // The signature is never unloaded.
2074 assert(Arguments::is_interpreter_only() || (m->has_compiled_code() &&
2075 m->code()->entry_point() == m->from_compiled_entry()),
2076 "MH intrinsic invariant");
2077 *met = m(); // insert the element
2078 ml.notify_all();
2079 return m();
2080 }
2081 }
2082
2083 // Throw OOM or the pending exception in the JavaThread
2084 if (throw_error && !HAS_PENDING_EXCEPTION) {
2085 THROW_MSG_NULL(vmSymbols::java_lang_OutOfMemoryError(),
2086 "Out of space in CodeCache for method handle intrinsic");
2087 }
2088 return nullptr;
2089 }
2090
2091 #if INCLUDE_CDS
2092 void SystemDictionary::get_all_method_handle_intrinsics(GrowableArray<Method*>* methods) {
2093 auto do_method = [&] (InvokeMethodKey& key, Method*& m) {
2094 methods->append(m);
2095 };
2096 _invoke_method_intrinsic_table->iterate_all(do_method);
2097 }
2098
2099 void SystemDictionary::restore_archived_method_handle_intrinsics() {
2100 if (UseSharedSpaces) {
2101 EXCEPTION_MARK;
2102 restore_archived_method_handle_intrinsics_impl(THREAD);
2103 if (HAS_PENDING_EXCEPTION) {
2104 vm_exit_during_initialization(err_msg("Failed to restore archived method handle intrinsics"));
2105 }
2106 }
2107 }
2108
2109 void SystemDictionary::restore_archived_method_handle_intrinsics_impl(TRAPS) {
2110 Array<Method*>* list = MetaspaceShared::archived_method_handle_intrinsics();
2111 for (int i = 0; i < list->length(); i++) {
2112 methodHandle m(THREAD, list->at(i));
2113 Method::restore_archived_method_handle_intrinsic(m, CHECK);
2114 m->constants()->restore_unshareable_info(CHECK);
2115 if (!Arguments::is_interpreter_only() || m->intrinsic_id() == vmIntrinsics::_linkToNative) {
2116 AdapterHandlerLibrary::create_native_wrapper(m);
2117 if (!m->has_compiled_code()) {
2118 ResourceMark rm(THREAD);
2119 vm_exit_during_initialization(err_msg("Failed to initialize method %s", m->external_name()));
2120 }
2121 }
2122
2123 const int iid_as_int = vmIntrinsics::as_int(m->intrinsic_id());
2124 InvokeMethodKey key(m->signature(), iid_as_int);
2125 bool created = _invoke_method_intrinsic_table->put(key, m());
2126 assert(created, "must be");
2127 }
2128 }
2129 #endif
2130
2131 // Helper for unpacking the return value from linkMethod and linkCallSite.
2132 static Method* unpack_method_and_appendix(Handle mname,
2133 Klass* accessing_klass,
2134 objArrayHandle appendix_box,
2135 Handle* appendix_result,
2136 TRAPS) {
2137 if (mname.not_null()) {
2138 Method* m = java_lang_invoke_MemberName::vmtarget(mname());
2139 if (m != nullptr) {
2140 oop appendix = appendix_box->obj_at(0);
2141 LogTarget(Info, methodhandles) lt;
2142 if (lt.develop_is_enabled()) {
2143 ResourceMark rm(THREAD);
2144 LogStream ls(lt);
2145 ls.print("Linked method=" INTPTR_FORMAT ": ", p2i(m));
2146 m->print_on(&ls);
2147 if (appendix != nullptr) { ls.print("appendix = "); appendix->print_on(&ls); }
2148 ls.cr();
2149 }
2150
2151 (*appendix_result) = Handle(THREAD, appendix);
2152 // the target is stored in the cpCache and if a reference to this
2153 // MemberName is dropped we need a way to make sure the
2154 // class_loader containing this method is kept alive.
2155 methodHandle mh(THREAD, m); // record_dependency can safepoint.
2156 ClassLoaderData* this_key = accessing_klass->class_loader_data();
2157 this_key->record_dependency(m->method_holder());
2158 return mh();
2159 }
2160 }
2161 THROW_MSG_NULL(vmSymbols::java_lang_LinkageError(), "bad value from MethodHandleNatives");
2162 }
2163
2164 Method* SystemDictionary::find_method_handle_invoker(Klass* klass,
2165 Symbol* name,
2166 Symbol* signature,
2167 Klass* accessing_klass,
2168 Handle* appendix_result,
2169 TRAPS) {
2170 guarantee(THREAD->can_call_java(), "");
2171 Handle method_type =
2172 SystemDictionary::find_method_handle_type(signature, accessing_klass, CHECK_NULL);
2173
2174 int ref_kind = JVM_REF_invokeVirtual;
2175 oop name_oop = StringTable::intern(name, CHECK_NULL);
2176 Handle name_str (THREAD, name_oop);
2177 objArrayHandle appendix_box = oopFactory::new_objArray_handle(vmClasses::Object_klass(), 1, CHECK_NULL);
2178 assert(appendix_box->obj_at(0) == nullptr, "");
2179
2180 // This should not happen. JDK code should take care of that.
2181 if (accessing_klass == nullptr || method_type.is_null()) {
2182 THROW_MSG_NULL(vmSymbols::java_lang_InternalError(), "bad invokehandle");
2183 }
2184
2185 // call java.lang.invoke.MethodHandleNatives::linkMethod(... String, MethodType) -> MemberName
2186 JavaCallArguments args;
2187 args.push_oop(Handle(THREAD, accessing_klass->java_mirror()));
2188 args.push_int(ref_kind);
2189 args.push_oop(Handle(THREAD, klass->java_mirror()));
2190 args.push_oop(name_str);
2191 args.push_oop(method_type);
2192 args.push_oop(appendix_box);
2193 JavaValue result(T_OBJECT);
2194 JavaCalls::call_static(&result,
2195 vmClasses::MethodHandleNatives_klass(),
2196 vmSymbols::linkMethod_name(),
2197 vmSymbols::linkMethod_signature(),
2198 &args, CHECK_NULL);
2199 Handle mname(THREAD, result.get_oop());
2200 return unpack_method_and_appendix(mname, accessing_klass, appendix_box, appendix_result, THREAD);
2201 }
2202
2203 // Decide if we can globally cache a lookup of this class, to be returned to any client that asks.
2204 // We must ensure that all class loaders everywhere will reach this class, for any client.
2205 // This is a safe bet for public classes in java.lang, such as Object and String.
2206 // We also include public classes in java.lang.invoke, because they appear frequently in system-level method types.
2207 // Out of an abundance of caution, we do not include any other classes, not even for packages like java.util.
2208 static bool is_always_visible_class(oop mirror) {
2209 Klass* klass = java_lang_Class::as_Klass(mirror);
2210 if (klass->is_objArray_klass()) {
2211 klass = ObjArrayKlass::cast(klass)->bottom_klass(); // check element type
2212 }
2213 if (klass->is_typeArray_klass()) {
2214 return true; // primitive array
2215 }
2216 assert(klass->is_instance_klass(), "%s", klass->external_name());
2217 return klass->is_public() &&
2218 (InstanceKlass::cast(klass)->is_same_class_package(vmClasses::Object_klass()) || // java.lang
2219 InstanceKlass::cast(klass)->is_same_class_package(vmClasses::MethodHandle_klass())); // java.lang.invoke
2220 }
2221
2222 // Find or construct the Java mirror (java.lang.Class instance) for
2223 // the given field type signature, as interpreted relative to the
2224 // given class loader. Handles primitives, void, references, arrays,
2225 // and all other reflectable types, except method types.
2226 // N.B. Code in reflection should use this entry point.
2227 Handle SystemDictionary::find_java_mirror_for_type(Symbol* signature,
2228 Klass* accessing_klass,
2229 Handle class_loader,
2230 Handle protection_domain,
2231 SignatureStream::FailureMode failure_mode,
2232 TRAPS) {
2233 assert(accessing_klass == nullptr || (class_loader.is_null() && protection_domain.is_null()),
2234 "one or the other, or perhaps neither");
2235
2236 // What we have here must be a valid field descriptor,
2237 // and all valid field descriptors are supported.
2238 // Produce the same java.lang.Class that reflection reports.
2239 if (accessing_klass != nullptr) {
2240 class_loader = Handle(THREAD, accessing_klass->class_loader());
2241 protection_domain = Handle(THREAD, accessing_klass->protection_domain());
2242 }
2243 ResolvingSignatureStream ss(signature, class_loader, protection_domain, false);
2244 oop mirror_oop = ss.as_java_mirror(failure_mode, CHECK_NH);
2245 if (mirror_oop == nullptr) {
2246 return Handle(); // report failure this way
2247 }
2248 Handle mirror(THREAD, mirror_oop);
2249
2250 if (accessing_klass != nullptr) {
2251 // Check accessibility, emulating ConstantPool::verify_constant_pool_resolve.
2252 Klass* sel_klass = java_lang_Class::as_Klass(mirror());
2253 if (sel_klass != nullptr) {
2254 LinkResolver::check_klass_accessibility(accessing_klass, sel_klass, CHECK_NH);
2255 }
2256 }
2257 return mirror;
2258 }
2259
2260
2261 // Ask Java code to find or construct a java.lang.invoke.MethodType for the given
2262 // signature, as interpreted relative to the given class loader.
2263 // Because of class loader constraints, all method handle usage must be
2264 // consistent with this loader.
2265 Handle SystemDictionary::find_method_handle_type(Symbol* signature,
2266 Klass* accessing_klass,
2267 TRAPS) {
2268 Handle empty;
2269 OopHandle* o;
2270 {
2271 MutexLocker ml(THREAD, InvokeMethodTypeTable_lock);
2272 o = _invoke_method_type_table->get(signature);
2273 }
2274
2275 if (o != nullptr) {
2276 oop mt = o->resolve();
2277 assert(java_lang_invoke_MethodType::is_instance(mt), "");
2278 return Handle(THREAD, mt);
2279 } else if (!THREAD->can_call_java()) {
2280 warning("SystemDictionary::find_method_handle_type called from compiler thread"); // FIXME
2281 return Handle(); // do not attempt from within compiler, unless it was cached
2282 }
2283
2284 Handle class_loader, protection_domain;
2285 if (accessing_klass != nullptr) {
2286 class_loader = Handle(THREAD, accessing_klass->class_loader());
2287 protection_domain = Handle(THREAD, accessing_klass->protection_domain());
2288 }
2289 bool can_be_cached = true;
2290 int npts = ArgumentCount(signature).size();
2291 objArrayHandle pts = oopFactory::new_objArray_handle(vmClasses::Class_klass(), npts, CHECK_(empty));
2292 int arg = 0;
2293 Handle rt; // the return type from the signature
2294 ResourceMark rm(THREAD);
2295 for (SignatureStream ss(signature); !ss.is_done(); ss.next()) {
2296 oop mirror = nullptr;
2297 if (can_be_cached) {
2298 // Use neutral class loader to lookup candidate classes to be placed in the cache.
2299 mirror = ss.as_java_mirror(Handle(), Handle(),
2300 SignatureStream::ReturnNull, CHECK_(empty));
2301 if (mirror == nullptr || (ss.is_reference() && !is_always_visible_class(mirror))) {
2302 // Fall back to accessing_klass context.
2303 can_be_cached = false;
2304 }
2305 }
2306 if (!can_be_cached) {
2307 // Resolve, throwing a real error if it doesn't work.
2308 mirror = ss.as_java_mirror(class_loader, protection_domain,
2309 SignatureStream::NCDFError, CHECK_(empty));
2310 }
2311 assert(mirror != nullptr, "%s", ss.as_symbol()->as_C_string());
2312 if (ss.at_return_type())
2313 rt = Handle(THREAD, mirror);
2314 else
2315 pts->obj_at_put(arg++, mirror);
2316
2317 // Check accessibility.
2318 if (!java_lang_Class::is_primitive(mirror) && accessing_klass != nullptr) {
2319 Klass* sel_klass = java_lang_Class::as_Klass(mirror);
2320 mirror = nullptr; // safety
2321 // Emulate ConstantPool::verify_constant_pool_resolve.
2322 LinkResolver::check_klass_accessibility(accessing_klass, sel_klass, CHECK_(empty));
2323 }
2324 }
2325 assert(arg == npts, "");
2326
2327 // call java.lang.invoke.MethodHandleNatives::findMethodHandleType(Class rt, Class[] pts) -> MethodType
2328 JavaCallArguments args(Handle(THREAD, rt()));
2329 args.push_oop(pts);
2330 JavaValue result(T_OBJECT);
2331 JavaCalls::call_static(&result,
2332 vmClasses::MethodHandleNatives_klass(),
2333 vmSymbols::findMethodHandleType_name(),
2334 vmSymbols::findMethodHandleType_signature(),
2335 &args, CHECK_(empty));
2336 Handle method_type(THREAD, result.get_oop());
2337
2338 if (can_be_cached) {
2339 // We can cache this MethodType inside the JVM.
2340 MutexLocker ml(THREAD, InvokeMethodTypeTable_lock);
2341 bool created = false;
2342 assert(method_type != nullptr, "unexpected null");
2343 OopHandle* h = _invoke_method_type_table->get(signature);
2344 if (h == nullptr) {
2345 signature->make_permanent(); // The signature is never unloaded.
2346 OopHandle elem = OopHandle(Universe::vm_global(), method_type());
2347 bool created = _invoke_method_type_table->put(signature, elem);
2348 assert(created, "better be created");
2349 }
2350 }
2351 // report back to the caller with the MethodType
2352 return method_type;
2353 }
2354
2355 Handle SystemDictionary::find_field_handle_type(Symbol* signature,
2356 Klass* accessing_klass,
2357 TRAPS) {
2358 Handle empty;
2359 ResourceMark rm(THREAD);
2360 SignatureStream ss(signature, /*is_method=*/ false);
2361 if (!ss.is_done()) {
2362 Handle class_loader, protection_domain;
2363 if (accessing_klass != nullptr) {
2364 class_loader = Handle(THREAD, accessing_klass->class_loader());
2365 protection_domain = Handle(THREAD, accessing_klass->protection_domain());
2366 }
2367 oop mirror = ss.as_java_mirror(class_loader, protection_domain, SignatureStream::NCDFError, CHECK_(empty));
2368 ss.next();
2369 if (ss.is_done()) {
2370 return Handle(THREAD, mirror);
2371 }
2372 }
2373 return empty;
2374 }
2375
2376 // Ask Java code to find or construct a method handle constant.
2377 Handle SystemDictionary::link_method_handle_constant(Klass* caller,
2378 int ref_kind, //e.g., JVM_REF_invokeVirtual
2379 Klass* callee,
2380 Symbol* name,
2381 Symbol* signature,
2382 TRAPS) {
2383 Handle empty;
2384 if (caller == nullptr) {
2385 THROW_MSG_(vmSymbols::java_lang_InternalError(), "bad MH constant", empty);
2386 }
2387 Handle name_str = java_lang_String::create_from_symbol(name, CHECK_(empty));
2388 Handle signature_str = java_lang_String::create_from_symbol(signature, CHECK_(empty));
2389
2390 // Put symbolic info from the MH constant into freshly created MemberName and resolve it.
2391 Handle mname = vmClasses::MemberName_klass()->allocate_instance_handle(CHECK_(empty));
2392 java_lang_invoke_MemberName::set_clazz(mname(), callee->java_mirror());
2393 java_lang_invoke_MemberName::set_name (mname(), name_str());
2394 java_lang_invoke_MemberName::set_type (mname(), signature_str());
2395 java_lang_invoke_MemberName::set_flags(mname(), MethodHandles::ref_kind_to_flags(ref_kind));
2396
2397 if (ref_kind == JVM_REF_invokeVirtual &&
2398 MethodHandles::is_signature_polymorphic_public_name(callee, name)) {
2399 // Skip resolution for public signature polymorphic methods such as
2400 // j.l.i.MethodHandle.invoke()/invokeExact() and those on VarHandle
2401 // They require appendix argument which MemberName resolution doesn't handle.
2402 // There's special logic on JDK side to handle them
2403 // (see MethodHandles.linkMethodHandleConstant() and MethodHandles.findVirtualForMH()).
2404 } else {
2405 MethodHandles::resolve_MemberName(mname, caller, 0, false /*speculative_resolve*/, CHECK_(empty));
2406 }
2407
2408 // After method/field resolution succeeded, it's safe to resolve MH signature as well.
2409 Handle type = MethodHandles::resolve_MemberName_type(mname, caller, CHECK_(empty));
2410
2411 // call java.lang.invoke.MethodHandleNatives::linkMethodHandleConstant(Class caller, int refKind, Class callee, String name, Object type) -> MethodHandle
2412 JavaCallArguments args;
2413 args.push_oop(Handle(THREAD, caller->java_mirror())); // the referring class
2414 args.push_int(ref_kind);
2415 args.push_oop(Handle(THREAD, callee->java_mirror())); // the target class
2416 args.push_oop(name_str);
2417 args.push_oop(type);
2418 JavaValue result(T_OBJECT);
2419 JavaCalls::call_static(&result,
2420 vmClasses::MethodHandleNatives_klass(),
2421 vmSymbols::linkMethodHandleConstant_name(),
2422 vmSymbols::linkMethodHandleConstant_signature(),
2423 &args, CHECK_(empty));
2424 return Handle(THREAD, result.get_oop());
2425 }
2426
2427 // Ask Java to run a bootstrap method, in order to create a dynamic call site
2428 // while linking an invokedynamic op, or compute a constant for Dynamic_info CP entry
2429 // with linkage results being stored back into the bootstrap specifier.
2430 void SystemDictionary::invoke_bootstrap_method(BootstrapInfo& bootstrap_specifier, TRAPS) {
2431 // Resolve the bootstrap specifier, its name, type, and static arguments
2432 bootstrap_specifier.resolve_bsm(CHECK);
2433
2434 // This should not happen. JDK code should take care of that.
2435 if (bootstrap_specifier.caller() == nullptr || bootstrap_specifier.type_arg().is_null()) {
2436 THROW_MSG(vmSymbols::java_lang_InternalError(), "Invalid bootstrap method invocation with no caller or type argument");
2437 }
2438
2439 bool is_indy = bootstrap_specifier.is_method_call();
2440 objArrayHandle appendix_box;
2441 if (is_indy) {
2442 // Some method calls may require an appendix argument. Arrange to receive it.
2443 appendix_box = oopFactory::new_objArray_handle(vmClasses::Object_klass(), 1, CHECK);
2444 assert(appendix_box->obj_at(0) == nullptr, "");
2445 }
2446
2447 // call condy: java.lang.invoke.MethodHandleNatives::linkDynamicConstant(caller, bsm, type, info)
2448 // indy: java.lang.invoke.MethodHandleNatives::linkCallSite(caller, bsm, name, mtype, info, &appendix)
2449 JavaCallArguments args;
2450 args.push_oop(Handle(THREAD, bootstrap_specifier.caller_mirror()));
2451 args.push_oop(bootstrap_specifier.bsm());
2452 args.push_oop(bootstrap_specifier.name_arg());
2453 args.push_oop(bootstrap_specifier.type_arg());
2454 args.push_oop(bootstrap_specifier.arg_values());
2455 if (is_indy) {
2456 args.push_oop(appendix_box);
2457 }
2458 JavaValue result(T_OBJECT);
2459 JavaCalls::call_static(&result,
2460 vmClasses::MethodHandleNatives_klass(),
2461 is_indy ? vmSymbols::linkCallSite_name() : vmSymbols::linkDynamicConstant_name(),
2462 is_indy ? vmSymbols::linkCallSite_signature() : vmSymbols::linkDynamicConstant_signature(),
2463 &args, CHECK);
2464
2465 Handle value(THREAD, result.get_oop());
2466 if (is_indy) {
2467 Handle appendix;
2468 Method* method = unpack_method_and_appendix(value,
2469 bootstrap_specifier.caller(),
2470 appendix_box,
2471 &appendix, CHECK);
2472 methodHandle mh(THREAD, method);
2473 bootstrap_specifier.set_resolved_method(mh, appendix);
2474 } else {
2475 bootstrap_specifier.set_resolved_value(value);
2476 }
2477
2478 // sanity check
2479 assert(bootstrap_specifier.is_resolved() ||
2480 (bootstrap_specifier.is_method_call() &&
2481 bootstrap_specifier.resolved_method().not_null()), "bootstrap method call failed");
2482 }
2483
2484
2485 bool SystemDictionary::is_nonpublic_Object_method(Method* m) {
2486 assert(m != nullptr, "Unexpected nullptr Method*");
2487 return !m->is_public() && m->method_holder() == vmClasses::Object_klass();
2488 }
2489
2490 // ----------------------------------------------------------------------------
2491
2492 void SystemDictionary::print_on(outputStream *st) {
2493 CDS_ONLY(SystemDictionaryShared::print_on(st));
2494 GCMutexLocker mu(SystemDictionary_lock);
2495
2496 ClassLoaderDataGraph::print_dictionary(st);
2497
2498 // Placeholders
2499 PlaceholderTable::print_on(st);
2500 st->cr();
2501
2502 // loader constraints - print under SD_lock
2503 LoaderConstraintTable::print_on(st);
2504 st->cr();
2505
2506 ProtectionDomainCacheTable::print_on(st);
2507 st->cr();
2508 }
2509
2510 void SystemDictionary::print() { print_on(tty); }
2511
2512 void SystemDictionary::verify() {
2513
2514 GCMutexLocker mu(SystemDictionary_lock);
2515
2516 // Verify dictionary
2517 ClassLoaderDataGraph::verify_dictionary();
2518
2519 // Verify constraint table
2520 LoaderConstraintTable::verify();
2521
2522 // Verify protection domain table
2523 ProtectionDomainCacheTable::verify();
2524 }
2525
2526 void SystemDictionary::dump(outputStream *st, bool verbose) {
2527 assert_locked_or_safepoint(SystemDictionary_lock);
2528 if (verbose) {
2529 print_on(st);
2530 } else {
2531 CDS_ONLY(SystemDictionaryShared::print_table_statistics(st));
2532 ClassLoaderDataGraph::print_table_statistics(st);
2533 LoaderConstraintTable::print_table_statistics(st);
2534 ProtectionDomainCacheTable::print_table_statistics(st);
2535 }
2536 }
2537
2538 // Utility for dumping dictionaries.
2539 SystemDictionaryDCmd::SystemDictionaryDCmd(outputStream* output, bool heap) :
2540 DCmdWithParser(output, heap),
2541 _verbose("-verbose", "Dump the content of each dictionary entry for all class loaders",
2542 "BOOLEAN", false, "false") {
2543 _dcmdparser.add_dcmd_option(&_verbose);
2544 }
2545
2546 void SystemDictionaryDCmd::execute(DCmdSource source, TRAPS) {
2547 VM_DumpHashtable dumper(output(), VM_DumpHashtable::DumpSysDict,
2548 _verbose.value());
2549 VMThread::execute(&dumper);
2550 }