1 /*
2 * Copyright (c) 1997, 2024, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
24
25 #include "precompiled.hpp"
26 #include "cds/cdsConfig.hpp"
27 #include "cds/heapShared.hpp"
28 #include "classfile/classFileParser.hpp"
29 #include "classfile/classFileStream.hpp"
30 #include "classfile/classLoader.hpp"
31 #include "classfile/classLoaderData.inline.hpp"
32 #include "classfile/classLoaderDataGraph.inline.hpp"
33 #include "classfile/classLoaderExt.hpp"
34 #include "classfile/classLoadInfo.hpp"
35 #include "classfile/dictionary.hpp"
36 #include "classfile/javaClasses.inline.hpp"
37 #include "classfile/klassFactory.hpp"
38 #include "classfile/loaderConstraints.hpp"
39 #include "classfile/packageEntry.hpp"
40 #include "classfile/placeholders.hpp"
41 #include "classfile/protectionDomainCache.hpp"
42 #include "classfile/resolutionErrors.hpp"
43 #include "classfile/stringTable.hpp"
44 #include "classfile/symbolTable.hpp"
45 #include "classfile/systemDictionary.hpp"
46 #include "classfile/vmClasses.hpp"
47 #include "classfile/vmSymbols.hpp"
48 #include "gc/shared/gcTraceTime.inline.hpp"
49 #include "interpreter/bootstrapInfo.hpp"
50 #include "jfr/jfrEvents.hpp"
51 #include "jvm.h"
52 #include "logging/log.hpp"
53 #include "logging/logStream.hpp"
54 #include "memory/metaspaceClosure.hpp"
55 #include "memory/oopFactory.hpp"
56 #include "memory/resourceArea.hpp"
57 #include "memory/universe.hpp"
58 #include "oops/access.inline.hpp"
59 #include "oops/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
165 oop SystemDictionary::get_system_class_loader_impl(TRAPS) {
166 JavaValue result(T_OBJECT);
167 InstanceKlass* class_loader_klass = vmClasses::ClassLoader_klass();
168 JavaCalls::call_static(&result,
169 class_loader_klass,
170 vmSymbols::getSystemClassLoader_name(),
171 vmSymbols::void_classloader_signature(),
172 CHECK_NULL);
173 return result.get_oop();
174 }
175
176 oop SystemDictionary::get_platform_class_loader_impl(TRAPS) {
177 JavaValue result(T_OBJECT);
178 InstanceKlass* class_loader_klass = vmClasses::ClassLoader_klass();
179 JavaCalls::call_static(&result,
180 class_loader_klass,
181 vmSymbols::getPlatformClassLoader_name(),
182 vmSymbols::void_classloader_signature(),
183 CHECK_NULL);
184 return result.get_oop();
185 }
186
187 // Helper function
188 inline ClassLoaderData* class_loader_data(Handle class_loader) {
189 return ClassLoaderData::class_loader_data(class_loader());
190 }
191
192 ClassLoaderData* SystemDictionary::register_loader(Handle class_loader, bool create_mirror_cld) {
193 if (create_mirror_cld) {
194 // Add a new class loader data to the graph.
195 return ClassLoaderDataGraph::add(class_loader, true);
196 } else {
197 return (class_loader() == nullptr) ? ClassLoaderData::the_null_class_loader_data() :
198 ClassLoaderDataGraph::find_or_create(class_loader);
199 }
200 }
201
202 void SystemDictionary::set_system_loader(ClassLoaderData *cld) {
203 assert(_java_system_loader.is_empty(), "already set!");
204 _java_system_loader = cld->class_loader_handle();
205
206 }
207
208 void SystemDictionary::set_platform_loader(ClassLoaderData *cld) {
209 assert(_java_platform_loader.is_empty(), "already set!");
210 _java_platform_loader = cld->class_loader_handle();
211 }
212
213 // ----------------------------------------------------------------------------
214 // Parallel class loading check
215
216 static bool is_parallelCapable(Handle class_loader) {
217 if (class_loader.is_null()) return true;
218 return java_lang_ClassLoader::parallelCapable(class_loader());
219 }
220 // ----------------------------------------------------------------------------
221 // ParallelDefineClass flag does not apply to bootclass loader
222 static bool is_parallelDefine(Handle class_loader) {
223 if (class_loader.is_null()) return false;
224 if (AllowParallelDefineClass && java_lang_ClassLoader::parallelCapable(class_loader())) {
225 return true;
226 }
227 return false;
228 }
229
230 // Returns true if the passed class loader is the builtin application class loader
231 // or a custom system class loader. A customer system class loader can be
232 // specified via -Djava.system.class.loader.
233 bool SystemDictionary::is_system_class_loader(oop class_loader) {
234 if (class_loader == nullptr) {
235 return false;
236 }
237 return (class_loader->klass() == vmClasses::jdk_internal_loader_ClassLoaders_AppClassLoader_klass() ||
238 class_loader == _java_system_loader.peek());
239 }
240
241 // Returns true if the passed class loader is the platform class loader.
242 bool SystemDictionary::is_platform_class_loader(oop class_loader) {
243 if (class_loader == nullptr) {
244 return false;
245 }
246 return (class_loader->klass() == vmClasses::jdk_internal_loader_ClassLoaders_PlatformClassLoader_klass());
247 }
248
249 Handle SystemDictionary::get_loader_lock_or_null(Handle class_loader) {
250 // If class_loader is null or parallelCapable, the JVM doesn't acquire a lock while loading.
251 if (is_parallelCapable(class_loader)) {
252 return Handle();
253 } else {
254 return class_loader;
255 }
256 }
257
258 // ----------------------------------------------------------------------------
259 // Resolving of classes
260
261 Symbol* SystemDictionary::class_name_symbol(const char* name, Symbol* exception, TRAPS) {
262 if (name == nullptr) {
263 THROW_MSG_NULL(exception, "No class name given");
264 }
265 size_t name_len = strlen(name);
266 if (name_len > static_cast<size_t>(Symbol::max_length())) {
267 // It's impossible to create this class; the name cannot fit
268 // into the constant pool. If necessary report an abridged name
269 // in the exception message.
270 if (name_len > static_cast<size_t>(MaxStringPrintSize)) {
271 Exceptions::fthrow(THREAD_AND_LOCATION, exception,
272 "Class name exceeds maximum length of %d: %.*s ... (%zu characters omitted) ... %.*s",
273 Symbol::max_length(),
274 MaxStringPrintSize / 2,
275 name,
276 name_len - 2 * (MaxStringPrintSize / 2), // allows for odd value
277 MaxStringPrintSize / 2,
278 name + name_len - MaxStringPrintSize / 2);
279 }
280 else {
281 Exceptions::fthrow(THREAD_AND_LOCATION, exception,
282 "Class name exceeds maximum length of %d: %s",
283 Symbol::max_length(),
284 name);
285 }
286 return nullptr;
287 }
288 // Callers should ensure that the name is never an illegal UTF8 string.
289 assert(UTF8::is_legal_utf8((const unsigned char*)name, name_len, false),
290 "Class name is not a valid utf8 string.");
291
292 // Make a new symbol for the class name.
293 return SymbolTable::new_symbol(name);
294 }
295
296 #ifdef ASSERT
297 // Used to verify that class loading succeeded in adding k to the dictionary.
298 static void verify_dictionary_entry(Symbol* class_name, InstanceKlass* k) {
299 MutexLocker mu(SystemDictionary_lock);
300 ClassLoaderData* loader_data = k->class_loader_data();
301 Dictionary* dictionary = loader_data->dictionary();
302 assert(class_name == k->name(), "Must be the same");
303 InstanceKlass* kk = dictionary->find_class(JavaThread::current(), class_name);
304 assert(kk == k, "should be present in dictionary");
305 }
306 #endif
307
308 static void handle_resolution_exception(Symbol* class_name, bool throw_error, TRAPS) {
309 if (HAS_PENDING_EXCEPTION) {
310 // If we have a pending exception we forward it to the caller, unless throw_error is true,
311 // in which case we have to check whether the pending exception is a ClassNotFoundException,
312 // and convert it to a NoClassDefFoundError and chain the original ClassNotFoundException.
313 if (throw_error && PENDING_EXCEPTION->is_a(vmClasses::ClassNotFoundException_klass())) {
314 ResourceMark rm(THREAD);
315 Handle e(THREAD, PENDING_EXCEPTION);
316 CLEAR_PENDING_EXCEPTION;
317 THROW_MSG_CAUSE(vmSymbols::java_lang_NoClassDefFoundError(), class_name->as_C_string(), e);
318 } else {
319 return; // the caller will throw the incoming exception
320 }
321 }
322 // If the class is not found, ie, caller has checked that klass is null, throw the appropriate
323 // error or exception depending on the value of throw_error.
324 ResourceMark rm(THREAD);
325 if (throw_error) {
326 THROW_MSG(vmSymbols::java_lang_NoClassDefFoundError(), class_name->as_C_string());
327 } else {
328 THROW_MSG(vmSymbols::java_lang_ClassNotFoundException(), class_name->as_C_string());
329 }
330 }
331
332 // Forwards to resolve_or_null
333
334 Klass* SystemDictionary::resolve_or_fail(Symbol* class_name, Handle class_loader, Handle protection_domain,
335 bool throw_error, TRAPS) {
336 Klass* klass = resolve_or_null(class_name, class_loader, protection_domain, THREAD);
337 // Check for pending exception or null klass, and throw exception
338 if (HAS_PENDING_EXCEPTION || klass == nullptr) {
339 handle_resolution_exception(class_name, throw_error, CHECK_NULL);
340 }
341 return klass;
342 }
343
344 // Forwards to resolve_array_class_or_null or resolve_instance_class_or_null
345
346 Klass* SystemDictionary::resolve_or_null(Symbol* class_name, Handle class_loader, Handle protection_domain, TRAPS) {
347 if (Signature::is_array(class_name)) {
348 return resolve_array_class_or_null(class_name, class_loader, protection_domain, THREAD);
349 } else {
350 assert(class_name != nullptr && !Signature::is_array(class_name), "must be");
351 if (Signature::has_envelope(class_name)) {
352 ResourceMark rm(THREAD);
353 // Ignore wrapping L and ;.
354 TempNewSymbol name = SymbolTable::new_symbol(class_name->as_C_string() + 1,
355 class_name->utf8_length() - 2);
356 return resolve_instance_class_or_null(name, class_loader, protection_domain, THREAD);
357 } else {
358 return resolve_instance_class_or_null(class_name, class_loader, protection_domain, THREAD);
359 }
360 }
361 }
362
363 // Forwards to resolve_instance_class_or_null
364
365 Klass* SystemDictionary::resolve_array_class_or_null(Symbol* class_name,
366 Handle class_loader,
367 Handle protection_domain,
368 TRAPS) {
369 assert(Signature::is_array(class_name), "must be array");
370 ResourceMark rm(THREAD);
371 SignatureStream ss(class_name, false);
372 int ndims = ss.skip_array_prefix(); // skip all '['s
373 Klass* k = nullptr;
374 BasicType t = ss.type();
375 if (ss.has_envelope()) {
376 Symbol* obj_class = ss.as_symbol();
377 k = SystemDictionary::resolve_instance_class_or_null(obj_class,
378 class_loader,
379 protection_domain,
380 CHECK_NULL);
381 if (k != nullptr) {
382 k = k->array_klass(ndims, CHECK_NULL);
383 }
384 } else {
385 k = Universe::typeArrayKlass(t);
386 k = k->array_klass(ndims, CHECK_NULL);
387 }
388 return k;
389 }
390
391 static inline void log_circularity_error(Symbol* name, PlaceholderEntry* probe) {
392 LogTarget(Debug, class, load, placeholders) lt;
393 if (lt.is_enabled()) {
394 ResourceMark rm;
395 LogStream ls(lt);
396 ls.print("ClassCircularityError detected for placeholder entry %s", name->as_C_string());
397 probe->print_on(&ls);
398 ls.cr();
399 }
400 }
401
402 // Must be called for any superclass or superinterface resolution
403 // during class definition to allow class circularity checking
404 // superinterface callers:
405 // parse_interfaces - from defineClass
406 // superclass callers:
407 // ClassFileParser - from defineClass
408 // load_shared_class - while loading a class from shared archive
409 // resolve_instance_class_or_null:
410 // via: handle_parallel_super_load
411 // when resolving a class that has an existing placeholder with
412 // a saved superclass [i.e. a defineClass is currently in progress]
413 // If another thread is trying to resolve the class, it must do
414 // superclass checks on its own thread to catch class circularity and
415 // to avoid deadlock.
416 //
417 // resolve_with_circularity_detection adds a DETECT_CIRCULARITY placeholder to the placeholder table before calling
418 // resolve_instance_class_or_null. ClassCircularityError is detected when a DETECT_CIRCULARITY or LOAD_INSTANCE
419 // placeholder for the same thread, class, classloader is found.
420 // This can be seen with logging option: -Xlog:class+load+placeholders=debug.
421 //
422 InstanceKlass* SystemDictionary::resolve_with_circularity_detection(Symbol* class_name,
423 Symbol* next_name,
424 Handle class_loader,
425 Handle protection_domain,
426 bool is_superclass,
427 TRAPS) {
428
429 assert(next_name != nullptr, "null superclass for resolving");
430 assert(!Signature::is_array(next_name), "invalid superclass name");
431 #if INCLUDE_CDS
432 if (CDSConfig::is_dumping_static_archive()) {
433 // Special processing for handling UNREGISTERED shared classes.
434 InstanceKlass* k = SystemDictionaryShared::lookup_super_for_unregistered_class(class_name,
435 next_name, is_superclass);
436 if (k) {
437 return k;
438 }
439 }
440 #endif // INCLUDE_CDS
441
442 // If class_name is already loaded, just return the superclass or superinterface.
443 // Make sure there's a placeholder for the class_name before resolving.
444 // This is used as a claim that this thread is currently loading superclass/classloader
445 // and for ClassCircularity checks.
446
447 ClassLoaderData* loader_data = class_loader_data(class_loader);
448 Dictionary* dictionary = loader_data->dictionary();
449
450 // can't throw error holding a lock
451 bool throw_circularity_error = false;
452 {
453 MutexLocker mu(THREAD, SystemDictionary_lock);
454 InstanceKlass* klassk = dictionary->find_class(THREAD, class_name);
455 InstanceKlass* quicksuperk;
456 // To support parallel loading: if class is done loading, just return the superclass
457 // if the next_name matches class->super()->name() and if the class loaders match.
458 if (klassk != nullptr && is_superclass &&
459 ((quicksuperk = klassk->java_super()) != nullptr) &&
460 ((quicksuperk->name() == next_name) &&
461 (quicksuperk->class_loader() == class_loader()))) {
462 return quicksuperk;
463 } else {
464 // Must check ClassCircularity before checking if superclass is already loaded.
465 PlaceholderEntry* probe = PlaceholderTable::get_entry(class_name, loader_data);
466 if (probe && probe->check_seen_thread(THREAD, PlaceholderTable::DETECT_CIRCULARITY)) {
467 log_circularity_error(class_name, probe);
468 throw_circularity_error = true;
469 }
470 }
471
472 if (!throw_circularity_error) {
473 // Be careful not to exit resolve_with_circularity_detection without removing this placeholder.
474 PlaceholderEntry* newprobe = PlaceholderTable::find_and_add(class_name,
475 loader_data,
476 PlaceholderTable::DETECT_CIRCULARITY,
477 next_name, THREAD);
478 }
479 }
480
481 if (throw_circularity_error) {
482 ResourceMark rm(THREAD);
483 THROW_MSG_NULL(vmSymbols::java_lang_ClassCircularityError(), class_name->as_C_string());
484 }
485
486 // Resolve the superclass or superinterface, check results on return
487 InstanceKlass* superk =
488 SystemDictionary::resolve_instance_class_or_null(next_name,
489 class_loader,
490 protection_domain,
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 Handle protection_domain, 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 protection_domain,
526 true,
527 CHECK);
528 }
529
530 // Bootstrap and non-parallel capable class loaders use the LOAD_INSTANCE placeholder to
531 // wait for parallel class loading and/or to check for circularity error for Xcomp when loading.
532 static bool needs_load_placeholder(Handle class_loader) {
533 return class_loader.is_null() || !is_parallelCapable(class_loader);
534 }
535
536 // Check for other threads loading this class either to throw CCE or wait in the case of the boot loader.
537 static InstanceKlass* handle_parallel_loading(JavaThread* current,
538 Symbol* name,
539 ClassLoaderData* loader_data,
540 bool must_wait_for_class_loading,
541 bool* throw_circularity_error) {
542 PlaceholderEntry* oldprobe = PlaceholderTable::get_entry(name, loader_data);
543 if (oldprobe != nullptr) {
544 // -Xcomp calls load_signature_classes which might result in loading
545 // a class that's already in the process of loading, so we detect CCE here also.
546 // Only need check_seen_thread once, not on each loop
547 if (oldprobe->check_seen_thread(current, PlaceholderTable::LOAD_INSTANCE)) {
548 log_circularity_error(name, oldprobe);
549 *throw_circularity_error = true;
550 return nullptr;
551 } else if (must_wait_for_class_loading) {
552 // Wait until the first thread has finished loading this class. Also wait until all the
553 // threads trying to load its superclass have removed their placeholders.
554 while (oldprobe != nullptr &&
555 (oldprobe->instance_load_in_progress() || oldprobe->circularity_detection_in_progress())) {
556
557 // LOAD_INSTANCE placeholders are used to implement parallel capable class loading
558 // for the bootclass loader.
559 SystemDictionary_lock->wait();
560
561 // Check if classloading completed while we were waiting
562 InstanceKlass* check = loader_data->dictionary()->find_class(current, name);
563 if (check != nullptr) {
564 // Klass is already loaded, so just return it
565 return check;
566 }
567 // check if other thread failed to load and cleaned up
568 oldprobe = PlaceholderTable::get_entry(name, loader_data);
569 }
570 }
571 }
572 return nullptr;
573 }
574
575 void SystemDictionary::post_class_load_event(EventClassLoad* event, const InstanceKlass* k, const ClassLoaderData* init_cld) {
576 assert(event != nullptr, "invariant");
577 assert(k != nullptr, "invariant");
578 event->set_loadedClass(k);
579 event->set_definingClassLoader(k->class_loader_data());
580 event->set_initiatingClassLoader(init_cld);
581 event->commit();
582 }
583
584 // SystemDictionary::resolve_instance_class_or_null is the main function for class name resolution.
585 // After checking if the InstanceKlass already exists, it checks for ClassCircularityError and
586 // whether the thread must wait for loading in parallel. It eventually calls load_instance_class,
587 // which will load the class via the bootstrap loader or call ClassLoader.loadClass().
588 // This can return null, an exception or an InstanceKlass.
589 InstanceKlass* SystemDictionary::resolve_instance_class_or_null(Symbol* name,
590 Handle class_loader,
591 Handle protection_domain,
592 TRAPS) {
593 // name must be in the form of "java/lang/Object" -- cannot be "Ljava/lang/Object;"
594 DEBUG_ONLY(ResourceMark rm(THREAD));
595 assert(name != nullptr && !Signature::is_array(name) &&
596 !Signature::has_envelope(name), "invalid class name: %s", name == nullptr ? "nullptr" : name->as_C_string());
597
598 EventClassLoad class_load_start_event;
599
600 HandleMark hm(THREAD);
601
602 ClassLoaderData* loader_data = register_loader(class_loader);
603 Dictionary* dictionary = loader_data->dictionary();
604
605 // Do lookup to see if class already exists and the protection domain
606 // has the right access.
607 // This call uses find which checks protection domain already matches
608 // All subsequent calls use find_class, and set loaded_class so that
609 // before we return a result, we call out to java to check for valid protection domain.
610 InstanceKlass* probe = dictionary->find(THREAD, name, protection_domain);
611 if (probe != nullptr) return probe;
612
613 // Non-bootstrap class loaders will call out to class loader and
614 // define via jvm/jni_DefineClass which will acquire the
615 // class loader object lock to protect against multiple threads
616 // defining the class in parallel by accident.
617 // This lock must be acquired here so the waiter will find
618 // any successful result in the SystemDictionary and not attempt
619 // the define.
620 // ParallelCapable class loaders and the bootstrap classloader
621 // do not acquire lock here.
622 Handle lockObject = get_loader_lock_or_null(class_loader);
623 ObjectLocker ol(lockObject, THREAD);
624
625 bool circularity_detection_in_progress = false;
626 InstanceKlass* loaded_class = nullptr;
627 SymbolHandle superclassname; // Keep alive while loading in parallel thread.
628
629 guarantee(THREAD->can_call_java(),
630 "can not load classes with compiler thread: class=%s, classloader=%s",
631 name->as_C_string(),
632 class_loader.is_null() ? "null" : class_loader->klass()->name()->as_C_string());
633
634 // Check again (after locking) if the class already exists in SystemDictionary
635 {
636 MutexLocker mu(THREAD, SystemDictionary_lock);
637 InstanceKlass* check = dictionary->find_class(THREAD, name);
638 if (check != nullptr) {
639 // InstanceKlass is already loaded, but we still need to check protection domain below.
640 loaded_class = check;
641 } else {
642 PlaceholderEntry* placeholder = PlaceholderTable::get_entry(name, loader_data);
643 if (placeholder != nullptr && placeholder->circularity_detection_in_progress()) {
644 circularity_detection_in_progress = true;
645 superclassname = placeholder->next_klass_name();
646 assert(superclassname != nullptr, "superclass has to have a name");
647 }
648 }
649 }
650
651 // If the class is in the placeholder table with super_class set,
652 // handle superclass loading in progress.
653 if (circularity_detection_in_progress) {
654 handle_parallel_super_load(name, superclassname,
655 class_loader,
656 protection_domain,
657 CHECK_NULL);
658 }
659
660 bool throw_circularity_error = false;
661 if (loaded_class == nullptr) {
662 bool load_placeholder_added = false;
663
664 // Add placeholder entry to record loading instance class
665 // case 1. Bootstrap classloader
666 // This classloader supports parallelism at the classloader level
667 // but only allows a single thread to load a class/classloader pair.
668 // The LOAD_INSTANCE placeholder is the mechanism for mutual exclusion.
669 // case 2. parallelCapable user level classloaders
670 // These class loaders lock a per-class object lock when ClassLoader.loadClass()
671 // is called. A LOAD_INSTANCE placeholder isn't used for mutual exclusion.
672 // case 3. traditional classloaders that rely on the classloader object lock
673 // There should be no need for need for LOAD_INSTANCE for mutual exclusion,
674 // except the LOAD_INSTANCE placeholder is used to detect CCE for -Xcomp.
675 // TODO: should also be used to detect CCE for parallel capable class loaders but it's not.
676 {
677 MutexLocker mu(THREAD, SystemDictionary_lock);
678 if (needs_load_placeholder(class_loader)) {
679 loaded_class = handle_parallel_loading(THREAD,
680 name,
681 loader_data,
682 class_loader.is_null(),
683 &throw_circularity_error);
684 }
685
686 // Recheck if the class has been loaded for all class loader cases and
687 // add a LOAD_INSTANCE placeholder while holding the SystemDictionary_lock.
688 if (!throw_circularity_error && loaded_class == nullptr) {
689 InstanceKlass* check = dictionary->find_class(THREAD, name);
690 if (check != nullptr) {
691 loaded_class = check;
692 } else if (needs_load_placeholder(class_loader)) {
693 // Add the LOAD_INSTANCE token. Threads will wait on loading to complete for this thread.
694 PlaceholderEntry* newprobe = PlaceholderTable::find_and_add(name, loader_data,
695 PlaceholderTable::LOAD_INSTANCE,
696 nullptr,
697 THREAD);
698 load_placeholder_added = true;
699 }
700 }
701 }
702
703 // Must throw error outside of owning lock
704 if (throw_circularity_error) {
705 assert(!HAS_PENDING_EXCEPTION && !load_placeholder_added, "circularity error cleanup");
706 ResourceMark rm(THREAD);
707 THROW_MSG_NULL(vmSymbols::java_lang_ClassCircularityError(), name->as_C_string());
708 }
709
710 // Be careful when modifying this code: once you have run
711 // PlaceholderTable::find_and_add(PlaceholderTable::LOAD_INSTANCE),
712 // you need to find_and_remove it before returning.
713 // So be careful to not exit with a CHECK_ macro between these calls.
714
715 if (loaded_class == nullptr) {
716 // Do actual loading
717 loaded_class = load_instance_class(name, class_loader, THREAD);
718 }
719
720 if (load_placeholder_added) {
721 // clean up placeholder entries for LOAD_INSTANCE success or error
722 // This brackets the SystemDictionary updates for both defining
723 // and initiating loaders
724 MutexLocker mu(THREAD, SystemDictionary_lock);
725 PlaceholderTable::find_and_remove(name, loader_data, PlaceholderTable::LOAD_INSTANCE, THREAD);
726 SystemDictionary_lock->notify_all();
727 }
728 }
729
730 if (HAS_PENDING_EXCEPTION || loaded_class == nullptr) {
731 return nullptr;
732 }
733
734 if (class_load_start_event.should_commit()) {
735 post_class_load_event(&class_load_start_event, loaded_class, loader_data);
736 }
737
738 // Make sure we have the right class in the dictionary
739 DEBUG_ONLY(verify_dictionary_entry(name, loaded_class));
740
741 if (protection_domain() != nullptr) {
742 // A SecurityManager (if installed) may prevent this protection_domain from accessing loaded_class
743 // by throwing a SecurityException.
744 dictionary->check_package_access(loaded_class, class_loader, protection_domain, CHECK_NULL);
745 }
746
747 return loaded_class;
748 }
749
750
751 // This routine does not lock the system dictionary.
752 //
753 // Since readers don't hold a lock, we must make sure that system
754 // dictionary entries are added to in a safe way (all links must
755 // be updated in an MT-safe manner). All entries are removed during class
756 // unloading, when this class loader is no longer referenced.
757 //
758 // Callers should be aware that an entry could be added just after
759 // Dictionary is read here, so the caller will not see
760 // the new entry.
761
762 InstanceKlass* SystemDictionary::find_instance_klass(Thread* current,
763 Symbol* class_name,
764 Handle class_loader,
765 Handle protection_domain) {
766
767 ClassLoaderData* loader_data = ClassLoaderData::class_loader_data_or_null(class_loader());
768 if (loader_data == nullptr) {
769 // If the ClassLoaderData has not been setup,
770 // then the class loader has no entries in the dictionary.
771 return nullptr;
772 }
773
774 Dictionary* dictionary = loader_data->dictionary();
775 return dictionary->find(current, class_name, protection_domain);
776 }
777
778 // Look for a loaded instance or array klass by name. Do not do any loading.
779 // return null in case of error.
780 Klass* SystemDictionary::find_instance_or_array_klass(Thread* current,
781 Symbol* class_name,
782 Handle class_loader,
783 Handle protection_domain) {
784 Klass* k = nullptr;
785 assert(class_name != nullptr, "class name must be non nullptr");
786
787 if (Signature::is_array(class_name)) {
788 // The name refers to an array. Parse the name.
789 // dimension and object_key in FieldArrayInfo are assigned as a
790 // side-effect of this call
791 SignatureStream ss(class_name, false);
792 int ndims = ss.skip_array_prefix(); // skip all '['s
793 BasicType t = ss.type();
794 if (t != T_OBJECT) {
795 k = Universe::typeArrayKlass(t);
796 } else {
797 k = SystemDictionary::find_instance_klass(current, ss.as_symbol(), class_loader, protection_domain);
798 }
799 if (k != nullptr) {
800 k = k->array_klass_or_null(ndims);
801 }
802 } else {
803 k = find_instance_klass(current, class_name, class_loader, protection_domain);
804 }
805 return k;
806 }
807
808 // Note: this method is much like resolve_class_from_stream, but
809 // does not publish the classes in the SystemDictionary.
810 // Handles Lookup.defineClass hidden.
811 InstanceKlass* SystemDictionary::resolve_hidden_class_from_stream(
812 ClassFileStream* st,
813 Symbol* class_name,
814 Handle class_loader,
815 const ClassLoadInfo& cl_info,
816 TRAPS) {
817
818 EventClassLoad class_load_start_event;
819 ClassLoaderData* loader_data;
820
821 // - for hidden classes that are not strong: create a new CLD that has a class holder and
822 // whose loader is the Lookup class's loader.
823 // - for hidden class: add the class to the Lookup class's loader's CLD.
824 assert (cl_info.is_hidden(), "only used for hidden classes");
825 bool create_mirror_cld = !cl_info.is_strong_hidden();
826 loader_data = register_loader(class_loader, create_mirror_cld);
827
828 assert(st != nullptr, "invariant");
829
830 // Parse stream and create a klass.
831 InstanceKlass* k = KlassFactory::create_from_stream(st,
832 class_name,
833 loader_data,
834 cl_info,
835 CHECK_NULL);
836 assert(k != nullptr, "no klass created");
837
838 // Hidden classes that are not strong must update ClassLoaderData holder
839 // so that they can be unloaded when the mirror is no longer referenced.
840 if (!cl_info.is_strong_hidden()) {
841 k->class_loader_data()->initialize_holder(Handle(THREAD, k->java_mirror()));
842 }
843
844 // Add to class hierarchy, and do possible deoptimizations.
845 k->add_to_hierarchy(THREAD);
846 // But, do not add to dictionary.
847
848 k->link_class(CHECK_NULL);
849
850 // notify jvmti
851 if (JvmtiExport::should_post_class_load()) {
852 JvmtiExport::post_class_load(THREAD, k);
853 }
854 if (class_load_start_event.should_commit()) {
855 post_class_load_event(&class_load_start_event, k, loader_data);
856 }
857
858 return k;
859 }
860
861 // Add a klass to the system from a stream (called by jni_DefineClass and
862 // JVM_DefineClass).
863 // Note: class_name can be null. In that case we do not know the name of
864 // the class until we have parsed the stream.
865 // This function either returns an InstanceKlass or throws an exception. It does
866 // not return null without a pending exception.
867 InstanceKlass* SystemDictionary::resolve_class_from_stream(
868 ClassFileStream* st,
869 Symbol* class_name,
870 Handle class_loader,
871 const ClassLoadInfo& cl_info,
872 TRAPS) {
873
874 HandleMark hm(THREAD);
875
876 ClassLoaderData* loader_data = register_loader(class_loader);
877
878 // Classloaders that support parallelism, e.g. bootstrap classloader,
879 // do not acquire lock here
880 Handle lockObject = get_loader_lock_or_null(class_loader);
881 ObjectLocker ol(lockObject, THREAD);
882
883 // Parse the stream and create a klass.
884 // Note that we do this even though this klass might
885 // already be present in the SystemDictionary, otherwise we would not
886 // throw potential ClassFormatErrors.
887 InstanceKlass* k = nullptr;
888
889 #if INCLUDE_CDS
890 if (!CDSConfig::is_dumping_static_archive()) {
891 k = SystemDictionaryShared::lookup_from_stream(class_name,
892 class_loader,
893 cl_info.protection_domain(),
894 st,
895 CHECK_NULL);
896 }
897 #endif
898
899 if (k == nullptr) {
900 k = KlassFactory::create_from_stream(st, class_name, loader_data, cl_info, CHECK_NULL);
901 }
902
903 assert(k != nullptr, "no klass created");
904 Symbol* h_name = k->name();
905 assert(class_name == nullptr || class_name == h_name, "name mismatch");
906
907 // Add class just loaded
908 // If a class loader supports parallel classloading, handle parallel define requests.
909 // find_or_define_instance_class may return a different InstanceKlass,
910 // in which case the old k would be deallocated
911 if (is_parallelCapable(class_loader)) {
912 k = find_or_define_instance_class(h_name, class_loader, k, CHECK_NULL);
913 } else {
914 define_instance_class(k, class_loader, THREAD);
915
916 // If defining the class throws an exception register 'k' for cleanup.
917 if (HAS_PENDING_EXCEPTION) {
918 assert(k != nullptr, "Must have an instance klass here!");
919 loader_data->add_to_deallocate_list(k);
920 return nullptr;
921 }
922 }
923
924 // Make sure we have an entry in the SystemDictionary on success
925 DEBUG_ONLY(verify_dictionary_entry(h_name, k));
926
927 return k;
928 }
929
930 InstanceKlass* SystemDictionary::resolve_from_stream(ClassFileStream* st,
931 Symbol* class_name,
932 Handle class_loader,
933 const ClassLoadInfo& cl_info,
934 TRAPS) {
935 if (cl_info.is_hidden()) {
936 return resolve_hidden_class_from_stream(st, class_name, class_loader, cl_info, CHECK_NULL);
937 } else {
938 return resolve_class_from_stream(st, class_name, class_loader, cl_info, CHECK_NULL);
939 }
940 }
941
942
943 #if INCLUDE_CDS
944 // Check if a shared class can be loaded by the specific classloader.
945 bool SystemDictionary::is_shared_class_visible(Symbol* class_name,
946 InstanceKlass* ik,
947 PackageEntry* pkg_entry,
948 Handle class_loader) {
949 assert(!ModuleEntryTable::javabase_moduleEntry()->is_patched(),
950 "Cannot use sharing if java.base is patched");
951
952 // (1) Check if we are loading into the same loader as in dump time.
953
954 if (ik->is_shared_boot_class()) {
955 if (class_loader() != nullptr) {
956 return false;
957 }
958 } else if (ik->is_shared_platform_class()) {
959 if (class_loader() != java_platform_loader()) {
960 return false;
961 }
962 } else if (ik->is_shared_app_class()) {
963 if (class_loader() != java_system_loader()) {
964 return false;
965 }
966 } else {
967 // ik was loaded by a custom loader during dump time
968 if (class_loader_data(class_loader)->is_builtin_class_loader_data()) {
969 return false;
970 } else {
971 return true;
972 }
973 }
974
975 // (2) Check if we are loading into the same module from the same location as in dump time.
976
977 if (CDSConfig::is_using_optimized_module_handling()) {
978 // Class visibility has not changed between dump time and run time, so a class
979 // that was visible (and thus archived) during dump time is always visible during runtime.
980 assert(SystemDictionary::is_shared_class_visible_impl(class_name, ik, pkg_entry, class_loader),
981 "visibility cannot change between dump time and runtime");
982 return true;
983 }
984 return is_shared_class_visible_impl(class_name, ik, pkg_entry, class_loader);
985 }
986
987 bool SystemDictionary::is_shared_class_visible_impl(Symbol* class_name,
988 InstanceKlass* ik,
989 PackageEntry* pkg_entry,
990 Handle class_loader) {
991 int scp_index = ik->shared_classpath_index();
992 assert(!ik->is_shared_unregistered_class(), "this function should be called for built-in classes only");
993 assert(scp_index >= 0, "must be");
994 SharedClassPathEntry* scp_entry = FileMapInfo::shared_path(scp_index);
995 if (!Universe::is_module_initialized()) {
996 assert(scp_entry != nullptr, "must be");
997 // At this point, no modules have been defined yet. KlassSubGraphInfo::check_allowed_klass()
998 // has restricted the classes can be loaded at this step to be only:
999 // [1] scp_entry->is_modules_image(): classes in java.base, or,
1000 // [2] HeapShared::is_a_test_class_in_unnamed_module(ik): classes in bootstrap/unnamed module
1001 assert(scp_entry->is_modules_image() || HeapShared::is_a_test_class_in_unnamed_module(ik),
1002 "only these classes can be loaded before the module system is initialized");
1003 assert(class_loader.is_null(), "sanity");
1004 return true;
1005 }
1006
1007 if (pkg_entry == nullptr) {
1008 // We might have looked up pkg_entry before the module system was initialized.
1009 // Need to reload it now.
1010 TempNewSymbol pkg_name = ClassLoader::package_from_class_name(class_name);
1011 if (pkg_name != nullptr) {
1012 pkg_entry = class_loader_data(class_loader)->packages()->lookup_only(pkg_name);
1013 }
1014 }
1015
1016 ModuleEntry* mod_entry = (pkg_entry == nullptr) ? nullptr : pkg_entry->module();
1017 bool should_be_in_named_module = (mod_entry != nullptr && mod_entry->is_named());
1018 bool was_archived_from_named_module = scp_entry->in_named_module();
1019 bool visible;
1020
1021 if (was_archived_from_named_module) {
1022 if (should_be_in_named_module) {
1023 // Is the module loaded from the same location as during dump time?
1024 visible = mod_entry->shared_path_index() == scp_index;
1025 if (visible) {
1026 assert(!mod_entry->is_patched(), "cannot load archived classes for patched module");
1027 }
1028 } else {
1029 // During dump time, this class was in a named module, but at run time, this class should be
1030 // in an unnamed module.
1031 visible = false;
1032 }
1033 } else {
1034 if (should_be_in_named_module) {
1035 // During dump time, this class was in an unnamed, but at run time, this class should be
1036 // in a named module.
1037 visible = false;
1038 } else {
1039 visible = true;
1040 }
1041 }
1042
1043 return visible;
1044 }
1045
1046 bool SystemDictionary::check_shared_class_super_type(InstanceKlass* klass, InstanceKlass* super_type,
1047 Handle class_loader, Handle protection_domain,
1048 bool is_superclass, TRAPS) {
1049 assert(super_type->is_shared(), "must be");
1050
1051 // Quick check if the super type has been already loaded.
1052 // + Don't do it for unregistered classes -- they can be unloaded so
1053 // super_type->class_loader_data() could be stale.
1054 // + Don't check if loader data is null, ie. the super_type isn't fully loaded.
1055 if (!super_type->is_shared_unregistered_class() && super_type->class_loader_data() != nullptr) {
1056 // Check if the superclass is loaded by the current class_loader
1057 Symbol* name = super_type->name();
1058 InstanceKlass* check = find_instance_klass(THREAD, name, class_loader, protection_domain);
1059 if (check == super_type) {
1060 return true;
1061 }
1062 }
1063
1064 Klass *found = resolve_with_circularity_detection(klass->name(), super_type->name(),
1065 class_loader, protection_domain, is_superclass, CHECK_false);
1066 if (found == super_type) {
1067 return true;
1068 } else {
1069 // The dynamically resolved super type is not the same as the one we used during dump time,
1070 // so we cannot use the class.
1071 return false;
1072 }
1073 }
1074
1075 bool SystemDictionary::check_shared_class_super_types(InstanceKlass* ik, Handle class_loader,
1076 Handle protection_domain, TRAPS) {
1077 // Check the superclass and interfaces. They must be the same
1078 // as in dump time, because the layout of <ik> depends on
1079 // the specific layout of ik->super() and ik->local_interfaces().
1080 //
1081 // If unexpected superclass or interfaces are found, we cannot
1082 // load <ik> from the shared archive.
1083
1084 if (ik->super() != nullptr) {
1085 bool check_super = check_shared_class_super_type(ik, InstanceKlass::cast(ik->super()),
1086 class_loader, protection_domain, true,
1087 CHECK_false);
1088 if (!check_super) {
1089 return false;
1090 }
1091 }
1092
1093 Array<InstanceKlass*>* interfaces = ik->local_interfaces();
1094 int num_interfaces = interfaces->length();
1095 for (int index = 0; index < num_interfaces; index++) {
1096 bool check_interface = check_shared_class_super_type(ik, interfaces->at(index), class_loader, protection_domain, false,
1097 CHECK_false);
1098 if (!check_interface) {
1099 return false;
1100 }
1101 }
1102
1103 return true;
1104 }
1105
1106 InstanceKlass* SystemDictionary::load_shared_lambda_proxy_class(InstanceKlass* ik,
1107 Handle class_loader,
1108 Handle protection_domain,
1109 PackageEntry* pkg_entry,
1110 TRAPS) {
1111 InstanceKlass* shared_nest_host = SystemDictionaryShared::get_shared_nest_host(ik);
1112 assert(shared_nest_host->is_shared(), "nest host must be in CDS archive");
1113 Symbol* cn = shared_nest_host->name();
1114 Klass *s = resolve_or_fail(cn, class_loader, protection_domain, true, CHECK_NULL);
1115 if (s != shared_nest_host) {
1116 // The dynamically resolved nest_host is not the same as the one we used during dump time,
1117 // so we cannot use ik.
1118 return nullptr;
1119 } else {
1120 assert(s->is_shared(), "must be");
1121 }
1122
1123 InstanceKlass* loaded_ik = load_shared_class(ik, class_loader, protection_domain, nullptr, pkg_entry, CHECK_NULL);
1124
1125 if (loaded_ik != nullptr) {
1126 assert(shared_nest_host->is_same_class_package(ik),
1127 "lambda proxy class and its nest host must be in the same package");
1128 // The lambda proxy class and its nest host have the same class loader and class loader data,
1129 // as verified in SystemDictionaryShared::add_lambda_proxy_class()
1130 assert(shared_nest_host->class_loader() == class_loader(), "mismatched class loader");
1131 assert(shared_nest_host->class_loader_data() == class_loader_data(class_loader), "mismatched class loader data");
1132 ik->set_nest_host(shared_nest_host);
1133 }
1134
1135 return loaded_ik;
1136 }
1137
1138 InstanceKlass* SystemDictionary::load_shared_class(InstanceKlass* ik,
1139 Handle class_loader,
1140 Handle protection_domain,
1141 const ClassFileStream *cfs,
1142 PackageEntry* pkg_entry,
1143 TRAPS) {
1144 assert(ik != nullptr, "sanity");
1145 assert(!ik->is_unshareable_info_restored(), "shared class can be restored only once");
1146 assert(Atomic::add(&ik->_shared_class_load_count, 1) == 1, "shared class loaded more than once");
1147 Symbol* class_name = ik->name();
1148
1149 if (!is_shared_class_visible(class_name, ik, pkg_entry, class_loader)) {
1150 ik->set_shared_loading_failed();
1151 return nullptr;
1152 }
1153
1154 bool check = check_shared_class_super_types(ik, class_loader, protection_domain, CHECK_NULL);
1155 if (!check) {
1156 ik->set_shared_loading_failed();
1157 return nullptr;
1158 }
1159
1160 InstanceKlass* new_ik = nullptr;
1161 // CFLH check is skipped for VM hidden classes (see KlassFactory::create_from_stream).
1162 // It will be skipped for shared VM hidden lambda proxy classes.
1163 if (!SystemDictionaryShared::is_hidden_lambda_proxy(ik)) {
1164 new_ik = KlassFactory::check_shared_class_file_load_hook(
1165 ik, class_name, class_loader, protection_domain, cfs, CHECK_NULL);
1166 }
1167 if (new_ik != nullptr) {
1168 // The class is changed by CFLH. Return the new class. The shared class is
1169 // not used.
1170 return new_ik;
1171 }
1172
1173 // Adjust methods to recover missing data. They need addresses for
1174 // interpreter entry points and their default native method address
1175 // must be reset.
1176
1177 // Shared classes are all currently loaded by either the bootstrap or
1178 // internal parallel class loaders, so this will never cause a deadlock
1179 // on a custom class loader lock.
1180 // Since this class is already locked with parallel capable class
1181 // loaders, including the bootstrap loader via the placeholder table,
1182 // this lock is currently a nop.
1183
1184 ClassLoaderData* loader_data = class_loader_data(class_loader);
1185 {
1186 HandleMark hm(THREAD);
1187 Handle lockObject = get_loader_lock_or_null(class_loader);
1188 ObjectLocker ol(lockObject, THREAD);
1189 // prohibited package check assumes all classes loaded from archive call
1190 // restore_unshareable_info which calls ik->set_package()
1191 ik->restore_unshareable_info(loader_data, protection_domain, pkg_entry, CHECK_NULL);
1192 }
1193
1194 load_shared_class_misc(ik, loader_data);
1195 return ik;
1196 }
1197
1198 void SystemDictionary::load_shared_class_misc(InstanceKlass* ik, ClassLoaderData* loader_data) {
1199 ik->print_class_load_logging(loader_data, nullptr, nullptr);
1200
1201 // For boot loader, ensure that GetSystemPackage knows that a class in this
1202 // package was loaded.
1203 if (loader_data->is_the_null_class_loader_data()) {
1204 s2 path_index = ik->shared_classpath_index();
1205 ik->set_classpath_index(path_index);
1206 }
1207
1208 // notify a class loaded from shared object
1209 ClassLoadingService::notify_class_loaded(ik, true /* shared class */);
1210 }
1211
1212 #endif // INCLUDE_CDS
1213
1214 InstanceKlass* SystemDictionary::load_instance_class_impl(Symbol* class_name, Handle class_loader, TRAPS) {
1215
1216 if (class_loader.is_null()) {
1217 ResourceMark rm(THREAD);
1218 PackageEntry* pkg_entry = nullptr;
1219 bool search_only_bootloader_append = false;
1220
1221 // Find the package in the boot loader's package entry table.
1222 TempNewSymbol pkg_name = ClassLoader::package_from_class_name(class_name);
1223 if (pkg_name != nullptr) {
1224 pkg_entry = class_loader_data(class_loader)->packages()->lookup_only(pkg_name);
1225 }
1226
1227 // Prior to attempting to load the class, enforce the boot loader's
1228 // visibility boundaries.
1229 if (!Universe::is_module_initialized()) {
1230 // During bootstrapping, prior to module initialization, any
1231 // class attempting to be loaded must be checked against the
1232 // java.base packages in the boot loader's PackageEntryTable.
1233 // No class outside of java.base is allowed to be loaded during
1234 // this bootstrapping window.
1235 if (pkg_entry == nullptr || pkg_entry->in_unnamed_module()) {
1236 // Class is either in the unnamed package or in
1237 // a named package within the unnamed module. Either
1238 // case is outside of java.base, do not attempt to
1239 // load the class post java.base definition. If
1240 // java.base has not been defined, let the class load
1241 // and its package will be checked later by
1242 // ModuleEntryTable::verify_javabase_packages.
1243 if (ModuleEntryTable::javabase_defined()) {
1244 return nullptr;
1245 }
1246 } else {
1247 // Check that the class' package is defined within java.base.
1248 ModuleEntry* mod_entry = pkg_entry->module();
1249 Symbol* mod_entry_name = mod_entry->name();
1250 if (mod_entry_name->fast_compare(vmSymbols::java_base()) != 0) {
1251 return nullptr;
1252 }
1253 }
1254 } else {
1255 // After the module system has been initialized, check if the class'
1256 // package is in a module defined to the boot loader.
1257 if (pkg_name == nullptr || pkg_entry == nullptr || pkg_entry->in_unnamed_module()) {
1258 // Class is either in the unnamed package, in a named package
1259 // within a module not defined to the boot loader or in a
1260 // a named package within the unnamed module. In all cases,
1261 // limit visibility to search for the class only in the boot
1262 // loader's append path.
1263 if (!ClassLoader::has_bootclasspath_append()) {
1264 // If there is no bootclasspath append entry, no need to continue
1265 // searching.
1266 return nullptr;
1267 }
1268 search_only_bootloader_append = true;
1269 }
1270 }
1271
1272 // Prior to bootstrapping's module initialization, never load a class outside
1273 // of the boot loader's module path
1274 assert(Universe::is_module_initialized() ||
1275 !search_only_bootloader_append,
1276 "Attempt to load a class outside of boot loader's module path");
1277
1278 // Search for classes in the CDS archive.
1279 InstanceKlass* k = nullptr;
1280
1281 #if INCLUDE_CDS
1282 if (CDSConfig::is_using_archive())
1283 {
1284 PerfTraceTime vmtimer(ClassLoader::perf_shared_classload_time());
1285 InstanceKlass* ik = SystemDictionaryShared::find_builtin_class(class_name);
1286 if (ik != nullptr && ik->is_shared_boot_class() && !ik->shared_loading_failed()) {
1287 SharedClassLoadingMark slm(THREAD, ik);
1288 k = load_shared_class(ik, class_loader, Handle(), nullptr, pkg_entry, CHECK_NULL);
1289 }
1290 }
1291 #endif
1292
1293 if (k == nullptr) {
1294 // Use VM class loader
1295 PerfTraceTime vmtimer(ClassLoader::perf_sys_classload_time());
1296 k = ClassLoader::load_class(class_name, pkg_entry, search_only_bootloader_append, CHECK_NULL);
1297 }
1298
1299 // find_or_define_instance_class may return a different InstanceKlass
1300 if (k != nullptr) {
1301 CDS_ONLY(SharedClassLoadingMark slm(THREAD, k);)
1302 k = find_or_define_instance_class(class_name, class_loader, k, CHECK_NULL);
1303 }
1304 return k;
1305 } else {
1306 // Use user specified class loader to load class. Call loadClass operation on class_loader.
1307 ResourceMark rm(THREAD);
1308
1309 JavaThread* jt = THREAD;
1310
1311 PerfClassTraceTime vmtimer(ClassLoader::perf_app_classload_time(),
1312 ClassLoader::perf_app_classload_selftime(),
1313 ClassLoader::perf_app_classload_count(),
1314 jt->get_thread_stat()->perf_recursion_counts_addr(),
1315 jt->get_thread_stat()->perf_timers_addr(),
1316 PerfClassTraceTime::CLASS_LOAD);
1317
1318 // Translate to external class name format, i.e., convert '/' chars to '.'
1319 Handle string = java_lang_String::externalize_classname(class_name, CHECK_NULL);
1320
1321 JavaValue result(T_OBJECT);
1322
1323 InstanceKlass* spec_klass = vmClasses::ClassLoader_klass();
1324
1325 // Call public unsynchronized loadClass(String) directly for all class loaders.
1326 // For parallelCapable class loaders, JDK >=7, loadClass(String, boolean) will
1327 // acquire a class-name based lock rather than the class loader object lock.
1328 // JDK < 7 already acquire the class loader lock in loadClass(String, boolean).
1329 JavaCalls::call_virtual(&result,
1330 class_loader,
1331 spec_klass,
1332 vmSymbols::loadClass_name(),
1333 vmSymbols::string_class_signature(),
1334 string,
1335 CHECK_NULL);
1336
1337 assert(result.get_type() == T_OBJECT, "just checking");
1338 oop obj = result.get_oop();
1339
1340 // Primitive classes return null since forName() can not be
1341 // used to obtain any of the Class objects representing primitives or void
1342 if ((obj != nullptr) && !(java_lang_Class::is_primitive(obj))) {
1343 InstanceKlass* k = InstanceKlass::cast(java_lang_Class::as_Klass(obj));
1344 // For user defined Java class loaders, check that the name returned is
1345 // the same as that requested. This check is done for the bootstrap
1346 // loader when parsing the class file.
1347 if (class_name == k->name()) {
1348 return k;
1349 }
1350 }
1351 // Class is not found or has the wrong name, return null
1352 return nullptr;
1353 }
1354 }
1355
1356 InstanceKlass* SystemDictionary::load_instance_class(Symbol* name,
1357 Handle class_loader,
1358 TRAPS) {
1359
1360 InstanceKlass* loaded_class = load_instance_class_impl(name, class_loader, CHECK_NULL);
1361
1362 // If everything was OK (no exceptions, no null return value), and
1363 // class_loader is NOT the defining loader, do a little more bookkeeping.
1364 if (loaded_class != nullptr &&
1365 loaded_class->class_loader() != class_loader()) {
1366
1367 ClassLoaderData* loader_data = class_loader_data(class_loader);
1368 check_constraints(loaded_class, loader_data, false, CHECK_NULL);
1369
1370 // Record dependency for non-parent delegation.
1371 // This recording keeps the defining class loader of the klass (loaded_class) found
1372 // from being unloaded while the initiating class loader is loaded
1373 // even if the reference to the defining class loader is dropped
1374 // before references to the initiating class loader.
1375 loader_data->record_dependency(loaded_class);
1376
1377 update_dictionary(THREAD, loaded_class, loader_data);
1378
1379 if (JvmtiExport::should_post_class_load()) {
1380 JvmtiExport::post_class_load(THREAD, loaded_class);
1381 }
1382 }
1383 return loaded_class;
1384 }
1385
1386 static void post_class_define_event(InstanceKlass* k, const ClassLoaderData* def_cld) {
1387 EventClassDefine event;
1388 if (event.should_commit()) {
1389 event.set_definedClass(k);
1390 event.set_definingClassLoader(def_cld);
1391 event.commit();
1392 }
1393 }
1394
1395 void SystemDictionary::define_instance_class(InstanceKlass* k, Handle class_loader, TRAPS) {
1396
1397 ClassLoaderData* loader_data = k->class_loader_data();
1398 assert(loader_data->class_loader() == class_loader(), "they must be the same");
1399
1400 // Bootstrap and other parallel classloaders don't acquire a lock,
1401 // they use placeholder token.
1402 // If a parallelCapable class loader calls define_instance_class instead of
1403 // find_or_define_instance_class to get here, we have a timing
1404 // hole with systemDictionary updates and check_constraints
1405 if (!is_parallelCapable(class_loader)) {
1406 assert(ObjectSynchronizer::current_thread_holds_lock(THREAD,
1407 get_loader_lock_or_null(class_loader)),
1408 "define called without lock");
1409 }
1410
1411 // Check class-loading constraints. Throw exception if violation is detected.
1412 // Grabs and releases SystemDictionary_lock
1413 // The check_constraints/find_class call and update_dictionary sequence
1414 // must be "atomic" for a specific class/classloader pair so we never
1415 // define two different instanceKlasses for that class/classloader pair.
1416 // Existing classloaders will call define_instance_class with the
1417 // classloader lock held
1418 // Parallel classloaders will call find_or_define_instance_class
1419 // which will require a token to perform the define class
1420 check_constraints(k, loader_data, true, CHECK);
1421
1422 // Register class just loaded with class loader (placed in ArrayList)
1423 // Note we do this before updating the dictionary, as this can
1424 // fail with an OutOfMemoryError (if it does, we will *not* put this
1425 // class in the dictionary and will not update the class hierarchy).
1426 // JVMTI FollowReferences needs to find the classes this way.
1427 if (k->class_loader() != nullptr) {
1428 methodHandle m(THREAD, Universe::loader_addClass_method());
1429 JavaValue result(T_VOID);
1430 JavaCallArguments args(class_loader);
1431 args.push_oop(Handle(THREAD, k->java_mirror()));
1432 JavaCalls::call(&result, m, &args, CHECK);
1433 }
1434
1435 // Add to class hierarchy, and do possible deoptimizations.
1436 k->add_to_hierarchy(THREAD);
1437
1438 // Add to systemDictionary - so other classes can see it.
1439 // Grabs and releases SystemDictionary_lock
1440 update_dictionary(THREAD, k, loader_data);
1441
1442 // notify jvmti
1443 if (JvmtiExport::should_post_class_load()) {
1444 JvmtiExport::post_class_load(THREAD, k);
1445 }
1446 post_class_define_event(k, loader_data);
1447 }
1448
1449 // Support parallel classloading
1450 // All parallel class loaders, including bootstrap classloader
1451 // lock a placeholder entry for this class/class_loader pair
1452 // to allow parallel defines of different classes for this class loader
1453 // With AllowParallelDefine flag==true, in case they do not synchronize around
1454 // FindLoadedClass/DefineClass, calls, we check for parallel
1455 // loading for them, wait if a defineClass is in progress
1456 // and return the initial requestor's results
1457 // This flag does not apply to the bootstrap classloader.
1458 // With AllowParallelDefine flag==false, call through to define_instance_class
1459 // which will throw LinkageError: duplicate class definition.
1460 // False is the requested default.
1461 // For better performance, the class loaders should synchronize
1462 // findClass(), i.e. FindLoadedClass/DefineClassIfAbsent or they
1463 // potentially waste time reading and parsing the bytestream.
1464 // Note: VM callers should ensure consistency of k/class_name,class_loader
1465 // Be careful when modifying this code: once you have run
1466 // PlaceholderTable::find_and_add(PlaceholderTable::DEFINE_CLASS),
1467 // you need to find_and_remove it before returning.
1468 // So be careful to not exit with a CHECK_ macro between these calls.
1469 InstanceKlass* SystemDictionary::find_or_define_helper(Symbol* class_name, Handle class_loader,
1470 InstanceKlass* k, TRAPS) {
1471
1472 Symbol* name_h = k->name();
1473 ClassLoaderData* loader_data = class_loader_data(class_loader);
1474 Dictionary* dictionary = loader_data->dictionary();
1475
1476 // Hold SD lock around find_class and placeholder creation for DEFINE_CLASS
1477 {
1478 MutexLocker mu(THREAD, SystemDictionary_lock);
1479 // First check if class already defined
1480 if (is_parallelDefine(class_loader)) {
1481 InstanceKlass* check = dictionary->find_class(THREAD, name_h);
1482 if (check != nullptr) {
1483 return check;
1484 }
1485 }
1486
1487 // Acquire define token for this class/classloader
1488 PlaceholderEntry* probe = PlaceholderTable::find_and_add(name_h, loader_data,
1489 PlaceholderTable::DEFINE_CLASS, nullptr, THREAD);
1490 // Wait if another thread defining in parallel
1491 // All threads wait - even those that will throw duplicate class: otherwise
1492 // caller is surprised by LinkageError: duplicate, but findLoadedClass fails
1493 // if other thread has not finished updating dictionary
1494 while (probe->definer() != nullptr) {
1495 SystemDictionary_lock->wait();
1496 }
1497 // Only special cases allow parallel defines and can use other thread's results
1498 // Other cases fall through, and may run into duplicate defines
1499 // caught by finding an entry in the SystemDictionary
1500 if (is_parallelDefine(class_loader) && (probe->instance_klass() != nullptr)) {
1501 InstanceKlass* ik = probe->instance_klass();
1502 PlaceholderTable::find_and_remove(name_h, loader_data, PlaceholderTable::DEFINE_CLASS, THREAD);
1503 SystemDictionary_lock->notify_all();
1504 #ifdef ASSERT
1505 InstanceKlass* check = dictionary->find_class(THREAD, name_h);
1506 assert(check != nullptr, "definer missed recording success");
1507 #endif
1508 return ik;
1509 } else {
1510 // This thread will define the class (even if earlier thread tried and had an error)
1511 probe->set_definer(THREAD);
1512 }
1513 }
1514
1515 define_instance_class(k, class_loader, THREAD);
1516
1517 // definer must notify any waiting threads
1518 {
1519 MutexLocker mu(THREAD, SystemDictionary_lock);
1520 PlaceholderEntry* probe = PlaceholderTable::get_entry(name_h, loader_data);
1521 assert(probe != nullptr, "DEFINE_CLASS placeholder lost?");
1522 if (!HAS_PENDING_EXCEPTION) {
1523 probe->set_instance_klass(k);
1524 }
1525 probe->set_definer(nullptr);
1526 PlaceholderTable::find_and_remove(name_h, loader_data, PlaceholderTable::DEFINE_CLASS, THREAD);
1527 SystemDictionary_lock->notify_all();
1528 }
1529
1530 return HAS_PENDING_EXCEPTION ? nullptr : k;
1531 }
1532
1533 // If a class loader supports parallel classloading handle parallel define requests.
1534 // find_or_define_instance_class may return a different InstanceKlass
1535 InstanceKlass* SystemDictionary::find_or_define_instance_class(Symbol* class_name, Handle class_loader,
1536 InstanceKlass* k, TRAPS) {
1537 InstanceKlass* defined_k = find_or_define_helper(class_name, class_loader, k, THREAD);
1538 // Clean up original InstanceKlass if duplicate or error
1539 if (!HAS_PENDING_EXCEPTION && defined_k != k) {
1540 // If a parallel capable class loader already defined this class, register 'k' for cleanup.
1541 assert(defined_k != nullptr, "Should have a klass if there's no exception");
1542 k->class_loader_data()->add_to_deallocate_list(k);
1543 } else if (HAS_PENDING_EXCEPTION) {
1544 // Remove this InstanceKlass from the LoaderConstraintTable if added.
1545 LoaderConstraintTable::remove_failed_loaded_klass(k, class_loader_data(class_loader));
1546 assert(defined_k == nullptr, "Should not have a klass if there's an exception");
1547 k->class_loader_data()->add_to_deallocate_list(k);
1548 }
1549 return defined_k;
1550 }
1551
1552
1553 // ----------------------------------------------------------------------------
1554 // GC support
1555
1556 // Assumes classes in the SystemDictionary are only unloaded at a safepoint
1557 bool SystemDictionary::do_unloading(GCTimer* gc_timer) {
1558
1559 bool unloading_occurred;
1560 bool is_concurrent = !SafepointSynchronize::is_at_safepoint();
1561 {
1562 GCTraceTime(Debug, gc, phases) t("ClassLoaderData", gc_timer);
1563 assert_locked_or_safepoint(ClassLoaderDataGraph_lock); // caller locks.
1564 // First, mark for unload all ClassLoaderData referencing a dead class loader.
1565 unloading_occurred = ClassLoaderDataGraph::do_unloading();
1566 if (unloading_occurred) {
1567 ConditionalMutexLocker ml2(Module_lock, is_concurrent);
1568 JFR_ONLY(Jfr::on_unloading_classes();)
1569 MANAGEMENT_ONLY(FinalizerService::purge_unloaded();)
1570 ConditionalMutexLocker ml1(SystemDictionary_lock, is_concurrent);
1571 ClassLoaderDataGraph::clean_module_and_package_info();
1572 LoaderConstraintTable::purge_loader_constraints();
1573 ResolutionErrorTable::purge_resolution_errors();
1574 }
1575 }
1576
1577 GCTraceTime(Debug, gc, phases) t("Trigger cleanups", gc_timer);
1578
1579 if (unloading_occurred) {
1580 SymbolTable::trigger_cleanup();
1581
1582 if (java_lang_System::allow_security_manager()) {
1583 // Oops referenced by the protection domain cache table may get unreachable independently
1584 // of the class loader (eg. cached protection domain oops). So we need to
1585 // explicitly unlink them here.
1586 // All protection domain oops are linked to the caller class, so if nothing
1587 // unloads, this is not needed.
1588 ProtectionDomainCacheTable::trigger_cleanup();
1589 } else {
1590 assert(ProtectionDomainCacheTable::number_of_entries() == 0, "should be empty");
1591 }
1592
1593 ConditionalMutexLocker ml(ClassInitError_lock, is_concurrent);
1594 InstanceKlass::clean_initialization_error_table();
1595 }
1596
1597 return unloading_occurred;
1598 }
1599
1600 void SystemDictionary::methods_do(void f(Method*)) {
1601 // Walk methods in loaded classes
1602
1603 {
1604 MutexLocker ml(ClassLoaderDataGraph_lock);
1605 ClassLoaderDataGraph::methods_do(f);
1606 }
1607
1608 auto doit = [&] (InvokeMethodKey key, Method* method) {
1609 if (method != nullptr) {
1610 f(method);
1611 }
1612 };
1613
1614 {
1615 MutexLocker ml(InvokeMethodIntrinsicTable_lock);
1616 _invoke_method_intrinsic_table->iterate_all(doit);
1617 }
1618
1619 }
1620
1621 // ----------------------------------------------------------------------------
1622 // Initialization
1623
1624 void SystemDictionary::initialize(TRAPS) {
1625 _invoke_method_intrinsic_table = new (mtClass) InvokeMethodIntrinsicTable();
1626 _invoke_method_type_table = new (mtClass) InvokeMethodTypeTable();
1627 ResolutionErrorTable::initialize();
1628 LoaderConstraintTable::initialize();
1629 PlaceholderTable::initialize();
1630 ProtectionDomainCacheTable::initialize();
1631 #if INCLUDE_CDS
1632 SystemDictionaryShared::initialize();
1633 #endif
1634 // Resolve basic classes
1635 vmClasses::resolve_all(CHECK);
1636 // Resolve classes used by archived heap objects
1637 if (CDSConfig::is_using_archive()) {
1638 HeapShared::resolve_classes(THREAD);
1639 }
1640 }
1641
1642 // Constraints on class loaders. The details of the algorithm can be
1643 // found in the OOPSLA'98 paper "Dynamic Class Loading in the Java
1644 // Virtual Machine" by Sheng Liang and Gilad Bracha. The basic idea is
1645 // that the dictionary needs to maintain a set of constraints that
1646 // must be satisfied by all classes in the dictionary.
1647 // if defining is true, then LinkageError if already in dictionary
1648 // if initiating loader, then ok if InstanceKlass matches existing entry
1649
1650 void SystemDictionary::check_constraints(InstanceKlass* k,
1651 ClassLoaderData* loader_data,
1652 bool defining,
1653 TRAPS) {
1654 ResourceMark rm(THREAD);
1655 stringStream ss;
1656 bool throwException = false;
1657
1658 {
1659 Symbol* name = k->name();
1660
1661 MutexLocker mu(THREAD, SystemDictionary_lock);
1662
1663 InstanceKlass* check = loader_data->dictionary()->find_class(THREAD, name);
1664 if (check != nullptr) {
1665 // If different InstanceKlass - duplicate class definition,
1666 // else - ok, class loaded by a different thread in parallel.
1667 // We should only have found it if it was done loading and ok to use.
1668
1669 if ((defining == true) || (k != check)) {
1670 throwException = true;
1671 ss.print("loader %s", loader_data->loader_name_and_id());
1672 ss.print(" attempted duplicate %s definition for %s. (%s)",
1673 k->external_kind(), k->external_name(), k->class_in_module_of_loader(false, true));
1674 } else {
1675 return;
1676 }
1677 }
1678
1679 if (throwException == false) {
1680 if (LoaderConstraintTable::check_or_update(k, loader_data, name) == false) {
1681 throwException = true;
1682 ss.print("loader constraint violation: loader %s", loader_data->loader_name_and_id());
1683 ss.print(" wants to load %s %s.",
1684 k->external_kind(), k->external_name());
1685 Klass *existing_klass = LoaderConstraintTable::find_constrained_klass(name, loader_data);
1686 if (existing_klass != nullptr && existing_klass->class_loader_data() != loader_data) {
1687 ss.print(" A different %s with the same name was previously loaded by %s. (%s)",
1688 existing_klass->external_kind(),
1689 existing_klass->class_loader_data()->loader_name_and_id(),
1690 existing_klass->class_in_module_of_loader(false, true));
1691 } else {
1692 ss.print(" (%s)", k->class_in_module_of_loader(false, true));
1693 }
1694 }
1695 }
1696 }
1697
1698 // Throw error now if needed (cannot throw while holding
1699 // SystemDictionary_lock because of rank ordering)
1700 if (throwException == true) {
1701 THROW_MSG(vmSymbols::java_lang_LinkageError(), ss.as_string());
1702 }
1703 }
1704
1705 // Update class loader data dictionary - done after check_constraint and add_to_hierarchy
1706 // have been called.
1707 void SystemDictionary::update_dictionary(JavaThread* current,
1708 InstanceKlass* k,
1709 ClassLoaderData* loader_data) {
1710 MonitorLocker mu1(SystemDictionary_lock);
1711
1712 // Make a new dictionary entry.
1713 Symbol* name = k->name();
1714 Dictionary* dictionary = loader_data->dictionary();
1715 InstanceKlass* sd_check = dictionary->find_class(current, name);
1716 if (sd_check == nullptr) {
1717 dictionary->add_klass(current, name, k);
1718 }
1719 mu1.notify_all();
1720 }
1721
1722 #if INCLUDE_CDS
1723 // Indicate that loader_data has initiated the loading of class k, which
1724 // has already been defined by a parent loader.
1725 // This API should be used only by AOTLinkedClassBulkLoader
1726 void SystemDictionary::add_to_initiating_loader(JavaThread* current,
1727 InstanceKlass* k,
1728 ClassLoaderData* loader_data) {
1729 assert(CDSConfig::is_using_aot_linked_classes(), "must be");
1730 assert_locked_or_safepoint(SystemDictionary_lock);
1731 Symbol* name = k->name();
1732 Dictionary* dictionary = loader_data->dictionary();
1733 assert(k->is_loaded(), "must be");
1734 assert(k->class_loader_data() != loader_data, "only for classes defined by a parent loader");
1735 assert(dictionary->find_class(current, name) == nullptr, "sanity");
1736 dictionary->add_klass(current, name, k);
1737 }
1738 #endif
1739
1740 // Try to find a class name using the loader constraints. The
1741 // loader constraints might know about a class that isn't fully loaded
1742 // yet and these will be ignored.
1743 Klass* SystemDictionary::find_constrained_instance_or_array_klass(
1744 Thread* current, Symbol* class_name, Handle class_loader) {
1745
1746 // First see if it has been loaded directly.
1747 // Force the protection domain to be null. (This removes protection checks.)
1748 Handle no_protection_domain;
1749 Klass* klass = find_instance_or_array_klass(current, class_name, class_loader,
1750 no_protection_domain);
1751 if (klass != nullptr)
1752 return klass;
1753
1754 // Now look to see if it has been loaded elsewhere, and is subject to
1755 // a loader constraint that would require this loader to return the
1756 // klass that is already loaded.
1757 if (Signature::is_array(class_name)) {
1758 // For array classes, their Klass*s are not kept in the
1759 // constraint table. The element Klass*s are.
1760 SignatureStream ss(class_name, false);
1761 int ndims = ss.skip_array_prefix(); // skip all '['s
1762 BasicType t = ss.type();
1763 if (t != T_OBJECT) {
1764 klass = Universe::typeArrayKlass(t);
1765 } else {
1766 MutexLocker mu(current, SystemDictionary_lock);
1767 klass = LoaderConstraintTable::find_constrained_klass(ss.as_symbol(), class_loader_data(class_loader));
1768 }
1769 // If element class already loaded, allocate array klass
1770 if (klass != nullptr) {
1771 klass = klass->array_klass_or_null(ndims);
1772 }
1773 } else {
1774 MutexLocker mu(current, SystemDictionary_lock);
1775 // Non-array classes are easy: simply check the constraint table.
1776 klass = LoaderConstraintTable::find_constrained_klass(class_name, class_loader_data(class_loader));
1777 }
1778
1779 return klass;
1780 }
1781
1782 bool SystemDictionary::add_loader_constraint(Symbol* class_name,
1783 Klass* klass_being_linked,
1784 Handle class_loader1,
1785 Handle class_loader2) {
1786 ClassLoaderData* loader_data1 = class_loader_data(class_loader1);
1787 ClassLoaderData* loader_data2 = class_loader_data(class_loader2);
1788
1789 Symbol* constraint_name = nullptr;
1790
1791 if (!Signature::is_array(class_name)) {
1792 constraint_name = class_name;
1793 } else {
1794 // For array classes, their Klass*s are not kept in the
1795 // constraint table. The element classes are.
1796 SignatureStream ss(class_name, false);
1797 ss.skip_array_prefix(); // skip all '['s
1798 if (!ss.has_envelope()) {
1799 return true; // primitive types always pass
1800 }
1801 constraint_name = ss.as_symbol();
1802 // Increment refcount to keep constraint_name alive after
1803 // SignatureStream is destructed. It will be decremented below
1804 // before returning.
1805 constraint_name->increment_refcount();
1806 }
1807
1808 Dictionary* dictionary1 = loader_data1->dictionary();
1809 Dictionary* dictionary2 = loader_data2->dictionary();
1810
1811 JavaThread* current = JavaThread::current();
1812 {
1813 MutexLocker mu_s(SystemDictionary_lock);
1814 InstanceKlass* klass1 = dictionary1->find_class(current, constraint_name);
1815 InstanceKlass* klass2 = dictionary2->find_class(current, constraint_name);
1816 bool result = LoaderConstraintTable::add_entry(constraint_name, klass1, loader_data1,
1817 klass2, loader_data2);
1818 #if INCLUDE_CDS
1819 if (CDSConfig::is_dumping_archive() && klass_being_linked != nullptr &&
1820 !klass_being_linked->is_shared()) {
1821 SystemDictionaryShared::record_linking_constraint(constraint_name,
1822 InstanceKlass::cast(klass_being_linked),
1823 class_loader1, class_loader2);
1824 }
1825 #endif // INCLUDE_CDS
1826 if (Signature::is_array(class_name)) {
1827 constraint_name->decrement_refcount();
1828 }
1829 return result;
1830 }
1831 }
1832
1833 // Add entry to resolution error table to record the error when the first
1834 // attempt to resolve a reference to a class has failed.
1835 void SystemDictionary::add_resolution_error(const constantPoolHandle& pool, int which,
1836 Symbol* error, const char* message,
1837 Symbol* cause, const char* cause_msg) {
1838 {
1839 MutexLocker ml(Thread::current(), SystemDictionary_lock);
1840 ResolutionErrorEntry* entry = ResolutionErrorTable::find_entry(pool, which);
1841 if (entry == nullptr) {
1842 ResolutionErrorTable::add_entry(pool, which, error, message, cause, cause_msg);
1843 }
1844 }
1845 }
1846
1847 // Delete a resolution error for RedefineClasses for a constant pool is going away
1848 void SystemDictionary::delete_resolution_error(ConstantPool* pool) {
1849 ResolutionErrorTable::delete_entry(pool);
1850 }
1851
1852 // Lookup resolution error table. Returns error if found, otherwise null.
1853 Symbol* SystemDictionary::find_resolution_error(const constantPoolHandle& pool, int which,
1854 const char** message,
1855 Symbol** cause, const char** cause_msg) {
1856
1857 {
1858 MutexLocker ml(Thread::current(), SystemDictionary_lock);
1859 ResolutionErrorEntry* entry = ResolutionErrorTable::find_entry(pool, which);
1860 if (entry != nullptr) {
1861 *message = entry->message();
1862 *cause = entry->cause();
1863 *cause_msg = entry->cause_msg();
1864 return entry->error();
1865 } else {
1866 return nullptr;
1867 }
1868 }
1869 }
1870
1871 // Add an entry to resolution error table to record an error in resolving or
1872 // validating a nest host. This is used to construct informative error
1873 // messages when IllegalAccessError's occur. If an entry already exists it will
1874 // be updated with the nest host error message.
1875
1876 void SystemDictionary::add_nest_host_error(const constantPoolHandle& pool,
1877 int which,
1878 const char* message) {
1879 {
1880 MutexLocker ml(Thread::current(), SystemDictionary_lock);
1881 ResolutionErrorEntry* entry = ResolutionErrorTable::find_entry(pool, which);
1882 if (entry != nullptr && entry->nest_host_error() == nullptr) {
1883 // An existing entry means we had a true resolution failure (LinkageError) with our nest host, but we
1884 // still want to add the error message for the higher-level access checks to report. We should
1885 // only reach here under the same error condition, so we can ignore the potential race with setting
1886 // the message. If we see it is already set then we can ignore it.
1887 entry->set_nest_host_error(message);
1888 } else {
1889 ResolutionErrorTable::add_entry(pool, which, message);
1890 }
1891 }
1892 }
1893
1894 // Lookup any nest host error
1895 const char* SystemDictionary::find_nest_host_error(const constantPoolHandle& pool, int which) {
1896 {
1897 MutexLocker ml(Thread::current(), SystemDictionary_lock);
1898 ResolutionErrorEntry* entry = ResolutionErrorTable::find_entry(pool, which);
1899 if (entry != nullptr) {
1900 return entry->nest_host_error();
1901 } else {
1902 return nullptr;
1903 }
1904 }
1905 }
1906
1907 // Signature constraints ensure that callers and callees agree about
1908 // the meaning of type names in their signatures. This routine is the
1909 // intake for constraints. It collects them from several places:
1910 //
1911 // * LinkResolver::resolve_method (if check_access is true) requires
1912 // that the resolving class (the caller) and the defining class of
1913 // the resolved method (the callee) agree on each type in the
1914 // method's signature.
1915 //
1916 // * LinkResolver::resolve_interface_method performs exactly the same
1917 // checks.
1918 //
1919 // * LinkResolver::resolve_field requires that the constant pool
1920 // attempting to link to a field agree with the field's defining
1921 // class about the type of the field signature.
1922 //
1923 // * klassVtable::initialize_vtable requires that, when a class
1924 // overrides a vtable entry allocated by a superclass, that the
1925 // overriding method (i.e., the callee) agree with the superclass
1926 // on each type in the method's signature.
1927 //
1928 // * klassItable::initialize_itable requires that, when a class fills
1929 // in its itables, for each non-abstract method installed in an
1930 // itable, the method (i.e., the callee) agree with the interface
1931 // on each type in the method's signature.
1932 //
1933 // All those methods have a boolean (check_access, checkconstraints)
1934 // which turns off the checks. This is used from specialized contexts
1935 // such as bootstrapping, dumping, and debugging.
1936 //
1937 // No direct constraint is placed between the class and its
1938 // supertypes. Constraints are only placed along linked relations
1939 // between callers and callees. When a method overrides or implements
1940 // an abstract method in a supertype (superclass or interface), the
1941 // constraints are placed as if the supertype were the caller to the
1942 // overriding method. (This works well, since callers to the
1943 // supertype have already established agreement between themselves and
1944 // the supertype.) As a result of all this, a class can disagree with
1945 // its supertype about the meaning of a type name, as long as that
1946 // class neither calls a relevant method of the supertype, nor is
1947 // called (perhaps via an override) from the supertype.
1948 //
1949 //
1950 // SystemDictionary::check_signature_loaders(sig, klass_being_linked, l1, l2)
1951 //
1952 // Make sure all class components (including arrays) in the given
1953 // signature will be resolved to the same class in both loaders.
1954 // Returns the name of the type that failed a loader constraint check, or
1955 // null if no constraint failed. No exception except OOME is thrown.
1956 // Arrays are not added to the loader constraint table, their elements are.
1957 Symbol* SystemDictionary::check_signature_loaders(Symbol* signature,
1958 Klass* klass_being_linked,
1959 Handle loader1, Handle loader2,
1960 bool is_method) {
1961 // Nothing to do if loaders are the same.
1962 if (loader1() == loader2()) {
1963 return nullptr;
1964 }
1965
1966 for (SignatureStream ss(signature, is_method); !ss.is_done(); ss.next()) {
1967 if (ss.is_reference()) {
1968 Symbol* sig = ss.as_symbol();
1969 // Note: In the future, if template-like types can take
1970 // arguments, we will want to recognize them and dig out class
1971 // names hiding inside the argument lists.
1972 if (!add_loader_constraint(sig, klass_being_linked, loader1, loader2)) {
1973 return sig;
1974 }
1975 }
1976 }
1977 return nullptr;
1978 }
1979
1980 Method* SystemDictionary::find_method_handle_intrinsic(vmIntrinsicID iid,
1981 Symbol* signature,
1982 TRAPS) {
1983
1984 const int iid_as_int = vmIntrinsics::as_int(iid);
1985 assert(MethodHandles::is_signature_polymorphic(iid) &&
1986 MethodHandles::is_signature_polymorphic_intrinsic(iid) &&
1987 iid != vmIntrinsics::_invokeGeneric,
1988 "must be a known MH intrinsic iid=%d: %s", iid_as_int, vmIntrinsics::name_at(iid));
1989
1990 InvokeMethodKey key(signature, iid_as_int);
1991 Method** met = nullptr;
1992
1993 // We only want one entry in the table for this (signature/id, method) pair but the code
1994 // to create the intrinsic method needs to be outside the lock.
1995 // The first thread claims the entry by adding the key and the other threads wait, until the
1996 // Method has been added as the value.
1997 {
1998 MonitorLocker ml(THREAD, InvokeMethodIntrinsicTable_lock);
1999 while (true) {
2000 bool created;
2001 met = _invoke_method_intrinsic_table->put_if_absent(key, &created);
2002 assert(met != nullptr, "either created or found");
2003 if (*met != nullptr) {
2004 return *met;
2005 } else if (created) {
2006 // The current thread won the race and will try to create the full entry.
2007 break;
2008 } else {
2009 // Another thread beat us to it, so wait for them to complete
2010 // and return *met; or if they hit an error we get another try.
2011 ml.wait();
2012 // Note it is not safe to read *met here as that entry could have
2013 // been deleted, so we must loop and try put_if_absent again.
2014 }
2015 }
2016 }
2017
2018 methodHandle m = Method::make_method_handle_intrinsic(iid, signature, THREAD);
2019 bool throw_error = HAS_PENDING_EXCEPTION;
2020 if (!throw_error && (!Arguments::is_interpreter_only() || iid == vmIntrinsics::_linkToNative)) {
2021 // Generate a compiled form of the MH intrinsic
2022 // linkToNative doesn't have interpreter-specific implementation, so always has to go through compiled version.
2023 AdapterHandlerLibrary::create_native_wrapper(m);
2024 // Check if have the compiled code.
2025 throw_error = (!m->has_compiled_code());
2026 }
2027
2028 {
2029 MonitorLocker ml(THREAD, InvokeMethodIntrinsicTable_lock);
2030 if (throw_error) {
2031 // Remove the entry and let another thread try, or get the same exception.
2032 bool removed = _invoke_method_intrinsic_table->remove(key);
2033 assert(removed, "must be the owner");
2034 ml.notify_all();
2035 } else {
2036 signature->make_permanent(); // The signature is never unloaded.
2037 assert(Arguments::is_interpreter_only() || (m->has_compiled_code() &&
2038 m->code()->entry_point() == m->from_compiled_entry()),
2039 "MH intrinsic invariant");
2040 *met = m(); // insert the element
2041 ml.notify_all();
2042 return m();
2043 }
2044 }
2045
2046 // Throw OOM or the pending exception in the JavaThread
2047 if (throw_error && !HAS_PENDING_EXCEPTION) {
2048 THROW_MSG_NULL(vmSymbols::java_lang_OutOfMemoryError(),
2049 "Out of space in CodeCache for method handle intrinsic");
2050 }
2051 return nullptr;
2052 }
2053
2054 #if INCLUDE_CDS
2055 void SystemDictionary::get_all_method_handle_intrinsics(GrowableArray<Method*>* methods) {
2056 assert(SafepointSynchronize::is_at_safepoint(), "must be");
2057 auto do_method = [&] (InvokeMethodKey& key, Method*& m) {
2058 methods->append(m);
2059 };
2060 _invoke_method_intrinsic_table->iterate_all(do_method);
2061 }
2062
2063 void SystemDictionary::restore_archived_method_handle_intrinsics() {
2064 if (UseSharedSpaces) {
2065 EXCEPTION_MARK;
2066 restore_archived_method_handle_intrinsics_impl(THREAD);
2067 if (HAS_PENDING_EXCEPTION) {
2068 // This is probably caused by OOM -- other parts of the CDS archive have direct pointers to
2069 // the archived method handle intrinsics, so we can't really recover from this failure.
2070 vm_exit_during_initialization(err_msg("Failed to restore archived method handle intrinsics. Try to increase heap size."));
2071 }
2072 }
2073 }
2074
2075 void SystemDictionary::restore_archived_method_handle_intrinsics_impl(TRAPS) {
2076 Array<Method*>* list = MetaspaceShared::archived_method_handle_intrinsics();
2077 for (int i = 0; i < list->length(); i++) {
2078 methodHandle m(THREAD, list->at(i));
2079 Method::restore_archived_method_handle_intrinsic(m, CHECK);
2080 m->constants()->restore_unshareable_info(CHECK);
2081 if (!Arguments::is_interpreter_only() || m->intrinsic_id() == vmIntrinsics::_linkToNative) {
2082 AdapterHandlerLibrary::create_native_wrapper(m);
2083 if (!m->has_compiled_code()) {
2084 ResourceMark rm(THREAD);
2085 vm_exit_during_initialization(err_msg("Failed to initialize method %s", m->external_name()));
2086 }
2087 }
2088
2089 // There's no need to grab the InvokeMethodIntrinsicTable_lock, as we are still very early in
2090 // VM start-up -- in init_globals2() -- so we are still running a single Java thread. It's not
2091 // possible to have a contention.
2092 const int iid_as_int = vmIntrinsics::as_int(m->intrinsic_id());
2093 InvokeMethodKey key(m->signature(), iid_as_int);
2094 bool created = _invoke_method_intrinsic_table->put(key, m());
2095 assert(created, "unexpected contention");
2096 }
2097 }
2098 #endif // INCLUDE_CDS
2099
2100 // Helper for unpacking the return value from linkMethod and linkCallSite.
2101 static Method* unpack_method_and_appendix(Handle mname,
2102 Klass* accessing_klass,
2103 objArrayHandle appendix_box,
2104 Handle* appendix_result,
2105 TRAPS) {
2106 if (mname.not_null()) {
2107 Method* m = java_lang_invoke_MemberName::vmtarget(mname());
2108 if (m != nullptr) {
2109 oop appendix = appendix_box->obj_at(0);
2110 LogTarget(Info, methodhandles) lt;
2111 if (lt.develop_is_enabled()) {
2112 ResourceMark rm(THREAD);
2113 LogStream ls(lt);
2114 ls.print("Linked method=" INTPTR_FORMAT ": ", p2i(m));
2115 m->print_on(&ls);
2116 if (appendix != nullptr) { ls.print("appendix = "); appendix->print_on(&ls); }
2117 ls.cr();
2118 }
2119
2120 (*appendix_result) = Handle(THREAD, appendix);
2121 // the target is stored in the cpCache and if a reference to this
2122 // MemberName is dropped we need a way to make sure the
2123 // class_loader containing this method is kept alive.
2124 methodHandle mh(THREAD, m); // record_dependency can safepoint.
2125 ClassLoaderData* this_key = accessing_klass->class_loader_data();
2126 this_key->record_dependency(m->method_holder());
2127 return mh();
2128 }
2129 }
2130 THROW_MSG_NULL(vmSymbols::java_lang_LinkageError(), "bad value from MethodHandleNatives");
2131 }
2132
2133 Method* SystemDictionary::find_method_handle_invoker(Klass* klass,
2134 Symbol* name,
2135 Symbol* signature,
2136 Klass* accessing_klass,
2137 Handle* appendix_result,
2138 TRAPS) {
2139 guarantee(THREAD->can_call_java(), "");
2140 Handle method_type =
2141 SystemDictionary::find_method_handle_type(signature, accessing_klass, CHECK_NULL);
2142
2143 int ref_kind = JVM_REF_invokeVirtual;
2144 oop name_oop = StringTable::intern(name, CHECK_NULL);
2145 Handle name_str (THREAD, name_oop);
2146 objArrayHandle appendix_box = oopFactory::new_objArray_handle(vmClasses::Object_klass(), 1, CHECK_NULL);
2147 assert(appendix_box->obj_at(0) == nullptr, "");
2148
2149 // This should not happen. JDK code should take care of that.
2150 if (accessing_klass == nullptr || method_type.is_null()) {
2151 THROW_MSG_NULL(vmSymbols::java_lang_InternalError(), "bad invokehandle");
2152 }
2153
2154 // call java.lang.invoke.MethodHandleNatives::linkMethod(... String, MethodType) -> MemberName
2155 JavaCallArguments args;
2156 args.push_oop(Handle(THREAD, accessing_klass->java_mirror()));
2157 args.push_int(ref_kind);
2158 args.push_oop(Handle(THREAD, klass->java_mirror()));
2159 args.push_oop(name_str);
2160 args.push_oop(method_type);
2161 args.push_oop(appendix_box);
2162 JavaValue result(T_OBJECT);
2163 JavaCalls::call_static(&result,
2164 vmClasses::MethodHandleNatives_klass(),
2165 vmSymbols::linkMethod_name(),
2166 vmSymbols::linkMethod_signature(),
2167 &args, CHECK_NULL);
2168 Handle mname(THREAD, result.get_oop());
2169 return unpack_method_and_appendix(mname, accessing_klass, appendix_box, appendix_result, THREAD);
2170 }
2171
2172 // Decide if we can globally cache a lookup of this class, to be returned to any client that asks.
2173 // We must ensure that all class loaders everywhere will reach this class, for any client.
2174 // This is a safe bet for public classes in java.lang, such as Object and String.
2175 // We also include public classes in java.lang.invoke, because they appear frequently in system-level method types.
2176 // Out of an abundance of caution, we do not include any other classes, not even for packages like java.util.
2177 static bool is_always_visible_class(oop mirror) {
2178 Klass* klass = java_lang_Class::as_Klass(mirror);
2179 if (klass->is_objArray_klass()) {
2180 klass = ObjArrayKlass::cast(klass)->bottom_klass(); // check element type
2181 }
2182 if (klass->is_typeArray_klass()) {
2183 return true; // primitive array
2184 }
2185 assert(klass->is_instance_klass(), "%s", klass->external_name());
2186 return klass->is_public() &&
2187 (InstanceKlass::cast(klass)->is_same_class_package(vmClasses::Object_klass()) || // java.lang
2188 InstanceKlass::cast(klass)->is_same_class_package(vmClasses::MethodHandle_klass())); // java.lang.invoke
2189 }
2190
2191 // Find or construct the Java mirror (java.lang.Class instance) for
2192 // the given field type signature, as interpreted relative to the
2193 // given class loader. Handles primitives, void, references, arrays,
2194 // and all other reflectable types, except method types.
2195 // N.B. Code in reflection should use this entry point.
2196 Handle SystemDictionary::find_java_mirror_for_type(Symbol* signature,
2197 Klass* accessing_klass,
2198 Handle class_loader,
2199 Handle protection_domain,
2200 SignatureStream::FailureMode failure_mode,
2201 TRAPS) {
2202 assert(accessing_klass == nullptr || (class_loader.is_null() && protection_domain.is_null()),
2203 "one or the other, or perhaps neither");
2204
2205 // What we have here must be a valid field descriptor,
2206 // and all valid field descriptors are supported.
2207 // Produce the same java.lang.Class that reflection reports.
2208 if (accessing_klass != nullptr) {
2209 class_loader = Handle(THREAD, accessing_klass->class_loader());
2210 protection_domain = Handle(THREAD, accessing_klass->protection_domain());
2211 }
2212 ResolvingSignatureStream ss(signature, class_loader, protection_domain, false);
2213 oop mirror_oop = ss.as_java_mirror(failure_mode, CHECK_NH);
2214 if (mirror_oop == nullptr) {
2215 return Handle(); // report failure this way
2216 }
2217 Handle mirror(THREAD, mirror_oop);
2218
2219 if (accessing_klass != nullptr) {
2220 // Check accessibility, emulating ConstantPool::verify_constant_pool_resolve.
2221 Klass* sel_klass = java_lang_Class::as_Klass(mirror());
2222 if (sel_klass != nullptr) {
2223 LinkResolver::check_klass_accessibility(accessing_klass, sel_klass, CHECK_NH);
2224 }
2225 }
2226 return mirror;
2227 }
2228
2229
2230 // Ask Java code to find or construct a java.lang.invoke.MethodType for the given
2231 // signature, as interpreted relative to the given class loader.
2232 // Because of class loader constraints, all method handle usage must be
2233 // consistent with this loader.
2234 Handle SystemDictionary::find_method_handle_type(Symbol* signature,
2235 Klass* accessing_klass,
2236 TRAPS) {
2237 Handle empty;
2238 OopHandle* o;
2239 {
2240 MutexLocker ml(THREAD, InvokeMethodTypeTable_lock);
2241 o = _invoke_method_type_table->get(signature);
2242 }
2243
2244 if (o != nullptr) {
2245 oop mt = o->resolve();
2246 assert(java_lang_invoke_MethodType::is_instance(mt), "");
2247 return Handle(THREAD, mt);
2248 } else if (!THREAD->can_call_java()) {
2249 warning("SystemDictionary::find_method_handle_type called from compiler thread"); // FIXME
2250 return Handle(); // do not attempt from within compiler, unless it was cached
2251 }
2252
2253 Handle class_loader, protection_domain;
2254 if (accessing_klass != nullptr) {
2255 class_loader = Handle(THREAD, accessing_klass->class_loader());
2256 protection_domain = Handle(THREAD, accessing_klass->protection_domain());
2257 }
2258 bool can_be_cached = true;
2259 int npts = ArgumentCount(signature).size();
2260 objArrayHandle pts = oopFactory::new_objArray_handle(vmClasses::Class_klass(), npts, CHECK_(empty));
2261 int arg = 0;
2262 Handle rt; // the return type from the signature
2263 ResourceMark rm(THREAD);
2264 for (SignatureStream ss(signature); !ss.is_done(); ss.next()) {
2265 oop mirror = nullptr;
2266 if (can_be_cached) {
2267 // Use neutral class loader to lookup candidate classes to be placed in the cache.
2268 mirror = ss.as_java_mirror(Handle(), Handle(),
2269 SignatureStream::ReturnNull, CHECK_(empty));
2270 if (mirror == nullptr || (ss.is_reference() && !is_always_visible_class(mirror))) {
2271 // Fall back to accessing_klass context.
2272 can_be_cached = false;
2273 }
2274 }
2275 if (!can_be_cached) {
2276 // Resolve, throwing a real error if it doesn't work.
2277 mirror = ss.as_java_mirror(class_loader, protection_domain,
2278 SignatureStream::NCDFError, CHECK_(empty));
2279 }
2280 assert(mirror != nullptr, "%s", ss.as_symbol()->as_C_string());
2281 if (ss.at_return_type())
2282 rt = Handle(THREAD, mirror);
2283 else
2284 pts->obj_at_put(arg++, mirror);
2285
2286 // Check accessibility.
2287 if (!java_lang_Class::is_primitive(mirror) && accessing_klass != nullptr) {
2288 Klass* sel_klass = java_lang_Class::as_Klass(mirror);
2289 mirror = nullptr; // safety
2290 // Emulate ConstantPool::verify_constant_pool_resolve.
2291 LinkResolver::check_klass_accessibility(accessing_klass, sel_klass, CHECK_(empty));
2292 }
2293 }
2294 assert(arg == npts, "");
2295
2296 // call java.lang.invoke.MethodHandleNatives::findMethodHandleType(Class rt, Class[] pts) -> MethodType
2297 JavaCallArguments args(Handle(THREAD, rt()));
2298 args.push_oop(pts);
2299 JavaValue result(T_OBJECT);
2300 JavaCalls::call_static(&result,
2301 vmClasses::MethodHandleNatives_klass(),
2302 vmSymbols::findMethodHandleType_name(),
2303 vmSymbols::findMethodHandleType_signature(),
2304 &args, CHECK_(empty));
2305 Handle method_type(THREAD, result.get_oop());
2306
2307 if (can_be_cached) {
2308 // We can cache this MethodType inside the JVM.
2309 MutexLocker ml(THREAD, InvokeMethodTypeTable_lock);
2310 bool created = false;
2311 assert(method_type != nullptr, "unexpected null");
2312 OopHandle* h = _invoke_method_type_table->get(signature);
2313 if (h == nullptr) {
2314 signature->make_permanent(); // The signature is never unloaded.
2315 OopHandle elem = OopHandle(Universe::vm_global(), method_type());
2316 bool created = _invoke_method_type_table->put(signature, elem);
2317 assert(created, "better be created");
2318 }
2319 }
2320 // report back to the caller with the MethodType
2321 return method_type;
2322 }
2323
2324 Handle SystemDictionary::find_field_handle_type(Symbol* signature,
2325 Klass* accessing_klass,
2326 TRAPS) {
2327 Handle empty;
2328 ResourceMark rm(THREAD);
2329 SignatureStream ss(signature, /*is_method=*/ false);
2330 if (!ss.is_done()) {
2331 Handle class_loader, protection_domain;
2332 if (accessing_klass != nullptr) {
2333 class_loader = Handle(THREAD, accessing_klass->class_loader());
2334 protection_domain = Handle(THREAD, accessing_klass->protection_domain());
2335 }
2336 oop mirror = ss.as_java_mirror(class_loader, protection_domain, SignatureStream::NCDFError, CHECK_(empty));
2337 ss.next();
2338 if (ss.is_done()) {
2339 return Handle(THREAD, mirror);
2340 }
2341 }
2342 return empty;
2343 }
2344
2345 // Ask Java code to find or construct a method handle constant.
2346 Handle SystemDictionary::link_method_handle_constant(Klass* caller,
2347 int ref_kind, //e.g., JVM_REF_invokeVirtual
2348 Klass* callee,
2349 Symbol* name,
2350 Symbol* signature,
2351 TRAPS) {
2352 Handle empty;
2353 if (caller == nullptr) {
2354 THROW_MSG_(vmSymbols::java_lang_InternalError(), "bad MH constant", empty);
2355 }
2356 Handle name_str = java_lang_String::create_from_symbol(name, CHECK_(empty));
2357 Handle signature_str = java_lang_String::create_from_symbol(signature, CHECK_(empty));
2358
2359 // Put symbolic info from the MH constant into freshly created MemberName and resolve it.
2360 Handle mname = vmClasses::MemberName_klass()->allocate_instance_handle(CHECK_(empty));
2361 java_lang_invoke_MemberName::set_clazz(mname(), callee->java_mirror());
2362 java_lang_invoke_MemberName::set_name (mname(), name_str());
2363 java_lang_invoke_MemberName::set_type (mname(), signature_str());
2364 java_lang_invoke_MemberName::set_flags(mname(), MethodHandles::ref_kind_to_flags(ref_kind));
2365
2366 if (ref_kind == JVM_REF_invokeVirtual &&
2367 MethodHandles::is_signature_polymorphic_public_name(callee, name)) {
2368 // Skip resolution for public signature polymorphic methods such as
2369 // j.l.i.MethodHandle.invoke()/invokeExact() and those on VarHandle
2370 // They require appendix argument which MemberName resolution doesn't handle.
2371 // There's special logic on JDK side to handle them
2372 // (see MethodHandles.linkMethodHandleConstant() and MethodHandles.findVirtualForMH()).
2373 } else {
2374 MethodHandles::resolve_MemberName(mname, caller, 0, false /*speculative_resolve*/, CHECK_(empty));
2375 }
2376
2377 // After method/field resolution succeeded, it's safe to resolve MH signature as well.
2378 Handle type = MethodHandles::resolve_MemberName_type(mname, caller, CHECK_(empty));
2379
2380 // call java.lang.invoke.MethodHandleNatives::linkMethodHandleConstant(Class caller, int refKind, Class callee, String name, Object type) -> MethodHandle
2381 JavaCallArguments args;
2382 args.push_oop(Handle(THREAD, caller->java_mirror())); // the referring class
2383 args.push_int(ref_kind);
2384 args.push_oop(Handle(THREAD, callee->java_mirror())); // the target class
2385 args.push_oop(name_str);
2386 args.push_oop(type);
2387 JavaValue result(T_OBJECT);
2388 JavaCalls::call_static(&result,
2389 vmClasses::MethodHandleNatives_klass(),
2390 vmSymbols::linkMethodHandleConstant_name(),
2391 vmSymbols::linkMethodHandleConstant_signature(),
2392 &args, CHECK_(empty));
2393 return Handle(THREAD, result.get_oop());
2394 }
2395
2396 // Ask Java to run a bootstrap method, in order to create a dynamic call site
2397 // while linking an invokedynamic op, or compute a constant for Dynamic_info CP entry
2398 // with linkage results being stored back into the bootstrap specifier.
2399 void SystemDictionary::invoke_bootstrap_method(BootstrapInfo& bootstrap_specifier, TRAPS) {
2400 // Resolve the bootstrap specifier, its name, type, and static arguments
2401 bootstrap_specifier.resolve_bsm(CHECK);
2402
2403 // This should not happen. JDK code should take care of that.
2404 if (bootstrap_specifier.caller() == nullptr || bootstrap_specifier.type_arg().is_null()) {
2405 THROW_MSG(vmSymbols::java_lang_InternalError(), "Invalid bootstrap method invocation with no caller or type argument");
2406 }
2407
2408 bool is_indy = bootstrap_specifier.is_method_call();
2409 objArrayHandle appendix_box;
2410 if (is_indy) {
2411 // Some method calls may require an appendix argument. Arrange to receive it.
2412 appendix_box = oopFactory::new_objArray_handle(vmClasses::Object_klass(), 1, CHECK);
2413 assert(appendix_box->obj_at(0) == nullptr, "");
2414 }
2415
2416 // call condy: java.lang.invoke.MethodHandleNatives::linkDynamicConstant(caller, bsm, type, info)
2417 // indy: java.lang.invoke.MethodHandleNatives::linkCallSite(caller, bsm, name, mtype, info, &appendix)
2418 JavaCallArguments args;
2419 args.push_oop(Handle(THREAD, bootstrap_specifier.caller_mirror()));
2420 args.push_oop(bootstrap_specifier.bsm());
2421 args.push_oop(bootstrap_specifier.name_arg());
2422 args.push_oop(bootstrap_specifier.type_arg());
2423 args.push_oop(bootstrap_specifier.arg_values());
2424 if (is_indy) {
2425 args.push_oop(appendix_box);
2426 }
2427 JavaValue result(T_OBJECT);
2428 JavaCalls::call_static(&result,
2429 vmClasses::MethodHandleNatives_klass(),
2430 is_indy ? vmSymbols::linkCallSite_name() : vmSymbols::linkDynamicConstant_name(),
2431 is_indy ? vmSymbols::linkCallSite_signature() : vmSymbols::linkDynamicConstant_signature(),
2432 &args, CHECK);
2433
2434 Handle value(THREAD, result.get_oop());
2435 if (is_indy) {
2436 Handle appendix;
2437 Method* method = unpack_method_and_appendix(value,
2438 bootstrap_specifier.caller(),
2439 appendix_box,
2440 &appendix, CHECK);
2441 methodHandle mh(THREAD, method);
2442 bootstrap_specifier.set_resolved_method(mh, appendix);
2443 } else {
2444 bootstrap_specifier.set_resolved_value(value);
2445 }
2446
2447 // sanity check
2448 assert(bootstrap_specifier.is_resolved() ||
2449 (bootstrap_specifier.is_method_call() &&
2450 bootstrap_specifier.resolved_method().not_null()), "bootstrap method call failed");
2451 }
2452
2453
2454 bool SystemDictionary::is_nonpublic_Object_method(Method* m) {
2455 assert(m != nullptr, "Unexpected nullptr Method*");
2456 return !m->is_public() && m->method_holder() == vmClasses::Object_klass();
2457 }
2458
2459 // ----------------------------------------------------------------------------
2460
2461 void SystemDictionary::print_on(outputStream *st) {
2462 CDS_ONLY(SystemDictionaryShared::print_on(st));
2463 GCMutexLocker mu(SystemDictionary_lock);
2464
2465 ClassLoaderDataGraph::print_dictionary(st);
2466
2467 // Placeholders
2468 PlaceholderTable::print_on(st);
2469 st->cr();
2470
2471 // loader constraints - print under SD_lock
2472 LoaderConstraintTable::print_on(st);
2473 st->cr();
2474
2475 ProtectionDomainCacheTable::print_on(st);
2476 st->cr();
2477 }
2478
2479 void SystemDictionary::print() { print_on(tty); }
2480
2481 void SystemDictionary::verify() {
2482
2483 GCMutexLocker mu(SystemDictionary_lock);
2484
2485 // Verify dictionary
2486 ClassLoaderDataGraph::verify_dictionary();
2487
2488 // Verify constraint table
2489 LoaderConstraintTable::verify();
2490
2491 // Verify protection domain table
2492 ProtectionDomainCacheTable::verify();
2493 }
2494
2495 void SystemDictionary::dump(outputStream *st, bool verbose) {
2496 assert_locked_or_safepoint(SystemDictionary_lock);
2497 if (verbose) {
2498 print_on(st);
2499 } else {
2500 CDS_ONLY(SystemDictionaryShared::print_table_statistics(st));
2501 ClassLoaderDataGraph::print_table_statistics(st);
2502 LoaderConstraintTable::print_table_statistics(st);
2503 ProtectionDomainCacheTable::print_table_statistics(st);
2504 }
2505 }
2506
2507 // Utility for dumping dictionaries.
2508 SystemDictionaryDCmd::SystemDictionaryDCmd(outputStream* output, bool heap) :
2509 DCmdWithParser(output, heap),
2510 _verbose("-verbose", "Dump the content of each dictionary entry for all class loaders",
2511 "BOOLEAN", false, "false") {
2512 _dcmdparser.add_dcmd_option(&_verbose);
2513 }
2514
2515 void SystemDictionaryDCmd::execute(DCmdSource source, TRAPS) {
2516 VM_DumpHashtable dumper(output(), VM_DumpHashtable::DumpSysDict,
2517 _verbose.value());
2518 VMThread::execute(&dumper);
2519 }