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