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