1 /*
2 * Copyright (c) 1997, 2024, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
24
25 #include "precompiled.hpp"
26 #include "cds/cdsConfig.hpp"
27 #include "cds/heapShared.hpp"
28 #include "classfile/classFileParser.hpp"
29 #include "classfile/classFileStream.hpp"
30 #include "classfile/classLoader.hpp"
31 #include "classfile/classLoaderData.inline.hpp"
32 #include "classfile/classLoaderDataGraph.inline.hpp"
33 #include "classfile/classLoaderExt.hpp"
34 #include "classfile/classLoadInfo.hpp"
35 #include "classfile/dictionary.hpp"
36 #include "classfile/javaClasses.inline.hpp"
37 #include "classfile/klassFactory.hpp"
38 #include "classfile/loaderConstraints.hpp"
39 #include "classfile/packageEntry.hpp"
40 #include "classfile/placeholders.hpp"
41 #include "classfile/protectionDomainCache.hpp"
42 #include "classfile/resolutionErrors.hpp"
43 #include "classfile/stringTable.hpp"
44 #include "classfile/symbolTable.hpp"
45 #include "classfile/systemDictionary.hpp"
46 #include "classfile/vmClasses.hpp"
47 #include "classfile/vmSymbols.hpp"
48 #include "gc/shared/gcTraceTime.inline.hpp"
49 #include "interpreter/bootstrapInfo.hpp"
50 #include "jfr/jfrEvents.hpp"
51 #include "jvm.h"
52 #include "logging/log.hpp"
53 #include "logging/logStream.hpp"
54 #include "memory/metaspaceClosure.hpp"
55 #include "memory/oopFactory.hpp"
56 #include "memory/resourceArea.hpp"
57 #include "memory/universe.hpp"
58 #include "oops/access.inline.hpp"
59 #include "oops/fieldStreams.inline.hpp"
60 #include "oops/instanceKlass.hpp"
61 #include "oops/klass.inline.hpp"
62 #include "oops/method.inline.hpp"
63 #include "oops/objArrayKlass.hpp"
64 #include "oops/objArrayOop.inline.hpp"
65 #include "oops/oop.inline.hpp"
66 #include "oops/oop.hpp"
67 #include "oops/oopHandle.hpp"
68 #include "oops/oopHandle.inline.hpp"
69 #include "oops/symbol.hpp"
70 #include "oops/typeArrayKlass.hpp"
71 #include "oops/inlineKlass.inline.hpp"
72 #include "prims/jvmtiExport.hpp"
73 #include "prims/methodHandles.hpp"
74 #include "runtime/arguments.hpp"
75 #include "runtime/atomic.hpp"
76 #include "runtime/handles.inline.hpp"
77 #include "runtime/java.hpp"
78 #include "runtime/javaCalls.hpp"
79 #include "runtime/mutexLocker.hpp"
80 #include "runtime/os.hpp"
81 #include "runtime/sharedRuntime.hpp"
82 #include "runtime/signature.hpp"
83 #include "runtime/synchronizer.hpp"
84 #include "services/classLoadingService.hpp"
85 #include "services/diagnosticCommand.hpp"
86 #include "services/finalizerService.hpp"
87 #include "services/threadService.hpp"
88 #include "utilities/macros.hpp"
89 #include "utilities/utf8.hpp"
90 #if INCLUDE_CDS
91 #include "classfile/systemDictionaryShared.hpp"
92 #endif
93 #if INCLUDE_JFR
94 #include "jfr/jfr.hpp"
95 #endif
96
97 class InvokeMethodKey : public StackObj {
98 private:
99 Symbol* _symbol;
100 intptr_t _iid;
101
102 public:
103 InvokeMethodKey(Symbol* symbol, intptr_t iid) :
104 _symbol(symbol),
105 _iid(iid) {}
106
107 static bool key_comparison(InvokeMethodKey const &k1, InvokeMethodKey const &k2){
108 return k1._symbol == k2._symbol && k1._iid == k2._iid;
109 }
110
111 static unsigned int compute_hash(const InvokeMethodKey &k) {
112 Symbol* sym = k._symbol;
113 intptr_t iid = k._iid;
114 unsigned int hash = (unsigned int) sym -> identity_hash();
115 return (unsigned int) (hash ^ iid);
116 }
117
118 };
119
120 using InvokeMethodIntrinsicTable = ResourceHashtable<InvokeMethodKey, Method*, 139, AnyObj::C_HEAP, mtClass,
121 InvokeMethodKey::compute_hash, InvokeMethodKey::key_comparison>;
122 static InvokeMethodIntrinsicTable* _invoke_method_intrinsic_table;
123 using InvokeMethodTypeTable = ResourceHashtable<SymbolHandle, OopHandle, 139, AnyObj::C_HEAP, mtClass, SymbolHandle::compute_hash>;
124 static InvokeMethodTypeTable* _invoke_method_type_table;
125
126 OopHandle SystemDictionary::_java_system_loader;
127 OopHandle SystemDictionary::_java_platform_loader;
128
129 // ----------------------------------------------------------------------------
130 // Java-level SystemLoader and PlatformLoader
131 oop SystemDictionary::java_system_loader() {
132 return _java_system_loader.resolve();
133 }
134
135 oop SystemDictionary::java_platform_loader() {
136 return _java_platform_loader.resolve();
137 }
138
139 void SystemDictionary::compute_java_loaders(TRAPS) {
140 if (_java_system_loader.is_empty()) {
141 oop system_loader = get_system_class_loader_impl(CHECK);
142 _java_system_loader = OopHandle(Universe::vm_global(), system_loader);
143 } else {
144 // It must have been restored from the archived module graph
145 assert(CDSConfig::is_using_archive(), "must be");
146 assert(CDSConfig::is_using_full_module_graph(), "must be");
147 DEBUG_ONLY(
148 oop system_loader = get_system_class_loader_impl(CHECK);
149 assert(_java_system_loader.resolve() == system_loader, "must be");
150 )
151 }
152
153 if (_java_platform_loader.is_empty()) {
154 oop platform_loader = get_platform_class_loader_impl(CHECK);
155 _java_platform_loader = OopHandle(Universe::vm_global(), platform_loader);
156 } else {
157 // It must have been restored from the archived module graph
158 assert(CDSConfig::is_using_archive(), "must be");
159 assert(CDSConfig::is_using_full_module_graph(), "must be");
160 DEBUG_ONLY(
161 oop platform_loader = get_platform_class_loader_impl(CHECK);
162 assert(_java_platform_loader.resolve() == platform_loader, "must be");
163 )
164 }
165 }
166
167 oop SystemDictionary::get_system_class_loader_impl(TRAPS) {
168 JavaValue result(T_OBJECT);
169 InstanceKlass* class_loader_klass = vmClasses::ClassLoader_klass();
170 JavaCalls::call_static(&result,
171 class_loader_klass,
172 vmSymbols::getSystemClassLoader_name(),
173 vmSymbols::void_classloader_signature(),
174 CHECK_NULL);
175 return result.get_oop();
176 }
177
178 oop SystemDictionary::get_platform_class_loader_impl(TRAPS) {
179 JavaValue result(T_OBJECT);
180 InstanceKlass* class_loader_klass = vmClasses::ClassLoader_klass();
181 JavaCalls::call_static(&result,
182 class_loader_klass,
183 vmSymbols::getPlatformClassLoader_name(),
184 vmSymbols::void_classloader_signature(),
185 CHECK_NULL);
186 return result.get_oop();
187 }
188
189 // Helper function
190 inline ClassLoaderData* class_loader_data(Handle class_loader) {
191 return ClassLoaderData::class_loader_data(class_loader());
192 }
193
194 ClassLoaderData* SystemDictionary::register_loader(Handle class_loader, bool create_mirror_cld) {
195 if (create_mirror_cld) {
196 // Add a new class loader data to the graph.
197 return ClassLoaderDataGraph::add(class_loader, true);
198 } else {
199 return (class_loader() == nullptr) ? ClassLoaderData::the_null_class_loader_data() :
200 ClassLoaderDataGraph::find_or_create(class_loader);
201 }
202 }
203
204 void SystemDictionary::set_system_loader(ClassLoaderData *cld) {
205 assert(_java_system_loader.is_empty(), "already set!");
206 _java_system_loader = cld->class_loader_handle();
207
208 }
209
210 void SystemDictionary::set_platform_loader(ClassLoaderData *cld) {
211 assert(_java_platform_loader.is_empty(), "already set!");
212 _java_platform_loader = cld->class_loader_handle();
213 }
214
215 // ----------------------------------------------------------------------------
216 // Parallel class loading check
217
218 static bool is_parallelCapable(Handle class_loader) {
219 if (class_loader.is_null()) return true;
220 return java_lang_ClassLoader::parallelCapable(class_loader());
221 }
222 // ----------------------------------------------------------------------------
223 // ParallelDefineClass flag does not apply to bootclass loader
224 static bool is_parallelDefine(Handle class_loader) {
225 if (class_loader.is_null()) return false;
226 if (AllowParallelDefineClass && java_lang_ClassLoader::parallelCapable(class_loader())) {
227 return true;
228 }
229 return false;
230 }
231
232 // Returns true if the passed class loader is the builtin application class loader
233 // or a custom system class loader. A customer system class loader can be
234 // specified via -Djava.system.class.loader.
235 bool SystemDictionary::is_system_class_loader(oop class_loader) {
236 if (class_loader == nullptr) {
237 return false;
238 }
239 return (class_loader->klass() == vmClasses::jdk_internal_loader_ClassLoaders_AppClassLoader_klass() ||
240 class_loader == _java_system_loader.peek());
241 }
242
243 // Returns true if the passed class loader is the platform class loader.
244 bool SystemDictionary::is_platform_class_loader(oop class_loader) {
245 if (class_loader == nullptr) {
246 return false;
247 }
248 return (class_loader->klass() == vmClasses::jdk_internal_loader_ClassLoaders_PlatformClassLoader_klass());
249 }
250
251 Handle SystemDictionary::get_loader_lock_or_null(Handle class_loader) {
252 // If class_loader is null or parallelCapable, the JVM doesn't acquire a lock while loading.
253 if (is_parallelCapable(class_loader)) {
254 return Handle();
255 } else {
256 return class_loader;
257 }
258 }
259
260 // ----------------------------------------------------------------------------
261 // Resolving of classes
262
263 Symbol* SystemDictionary::class_name_symbol(const char* name, Symbol* exception, TRAPS) {
264 if (name == nullptr) {
265 THROW_MSG_NULL(exception, "No class name given");
266 }
267 size_t name_len = strlen(name);
268 if (name_len > static_cast<size_t>(Symbol::max_length())) {
269 // It's impossible to create this class; the name cannot fit
270 // into the constant pool. If necessary report an abridged name
271 // in the exception message.
272 if (name_len > static_cast<size_t>(MaxStringPrintSize)) {
273 Exceptions::fthrow(THREAD_AND_LOCATION, exception,
274 "Class name exceeds maximum length of %d: %.*s ... (%zu characters omitted) ... %.*s",
275 Symbol::max_length(),
276 MaxStringPrintSize / 2,
277 name,
278 name_len - 2 * (MaxStringPrintSize / 2), // allows for odd value
279 MaxStringPrintSize / 2,
280 name + name_len - MaxStringPrintSize / 2);
281 }
282 else {
283 Exceptions::fthrow(THREAD_AND_LOCATION, exception,
284 "Class name exceeds maximum length of %d: %s",
285 Symbol::max_length(),
286 name);
287 }
288 return nullptr;
289 }
290 // Callers should ensure that the name is never an illegal UTF8 string.
291 assert(UTF8::is_legal_utf8((const unsigned char*)name, name_len, false),
292 "Class name is not a valid utf8 string.");
293
294 // Make a new symbol for the class name.
295 return SymbolTable::new_symbol(name);
296 }
297
298 #ifdef ASSERT
299 // Used to verify that class loading succeeded in adding k to the dictionary.
300 static void verify_dictionary_entry(Symbol* class_name, InstanceKlass* k) {
301 MutexLocker mu(SystemDictionary_lock);
302 ClassLoaderData* loader_data = k->class_loader_data();
303 Dictionary* dictionary = loader_data->dictionary();
304 assert(class_name == k->name(), "Must be the same");
305 InstanceKlass* kk = dictionary->find_class(JavaThread::current(), class_name);
306 assert(kk == k, "should be present in dictionary");
307 }
308 #endif
309
310 static void handle_resolution_exception(Symbol* class_name, bool throw_error, TRAPS) {
311 if (HAS_PENDING_EXCEPTION) {
312 // If we have a pending exception we forward it to the caller, unless throw_error is true,
313 // in which case we have to check whether the pending exception is a ClassNotFoundException,
314 // and convert it to a NoClassDefFoundError and chain the original ClassNotFoundException.
315 if (throw_error && PENDING_EXCEPTION->is_a(vmClasses::ClassNotFoundException_klass())) {
316 ResourceMark rm(THREAD);
317 Handle e(THREAD, PENDING_EXCEPTION);
318 CLEAR_PENDING_EXCEPTION;
319 THROW_MSG_CAUSE(vmSymbols::java_lang_NoClassDefFoundError(), class_name->as_C_string(), e);
320 } else {
321 return; // the caller will throw the incoming exception
322 }
323 }
324 // If the class is not found, ie, caller has checked that klass is null, throw the appropriate
325 // error or exception depending on the value of throw_error.
326 ResourceMark rm(THREAD);
327 if (throw_error) {
328 THROW_MSG(vmSymbols::java_lang_NoClassDefFoundError(), class_name->as_C_string());
329 } else {
330 THROW_MSG(vmSymbols::java_lang_ClassNotFoundException(), class_name->as_C_string());
331 }
332 }
333
334 // Forwards to resolve_or_null
335
336 Klass* SystemDictionary::resolve_or_fail(Symbol* class_name, Handle class_loader, Handle protection_domain,
337 bool throw_error, TRAPS) {
338 Klass* klass = resolve_or_null(class_name, class_loader, protection_domain, THREAD);
339 // Check for pending exception or null klass, and throw exception
340 if (HAS_PENDING_EXCEPTION || klass == nullptr) {
341 handle_resolution_exception(class_name, throw_error, CHECK_NULL);
342 }
343 return klass;
344 }
345
346 // Forwards to resolve_array_class_or_null or resolve_instance_class_or_null
347
348 Klass* SystemDictionary::resolve_or_null(Symbol* class_name, Handle class_loader, Handle protection_domain, TRAPS) {
349 if (Signature::is_array(class_name)) {
350 return resolve_array_class_or_null(class_name, class_loader, protection_domain, THREAD);
351 } else {
352 assert(class_name != nullptr && !Signature::is_array(class_name), "must be");
353 if (Signature::has_envelope(class_name)) {
354 ResourceMark rm(THREAD);
355 // Ignore wrapping L and ; (and Q and ; for value types).
356 TempNewSymbol name = SymbolTable::new_symbol(class_name->as_C_string() + 1,
357 class_name->utf8_length() - 2);
358 return resolve_instance_class_or_null(name, class_loader, protection_domain, THREAD);
359 } else {
360 return resolve_instance_class_or_null(class_name, class_loader, protection_domain, THREAD);
361 }
362 }
363 }
364
365 // Forwards to resolve_instance_class_or_null
366
367 Klass* SystemDictionary::resolve_array_class_or_null(Symbol* class_name,
368 Handle class_loader,
369 Handle protection_domain,
370 TRAPS) {
371 assert(Signature::is_array(class_name), "must be array");
372 ResourceMark rm(THREAD);
373 SignatureStream ss(class_name, false);
374 int ndims = ss.skip_array_prefix(); // skip all '['s
375 Klass* k = nullptr;
376 BasicType t = ss.type();
377 if (ss.has_envelope()) {
378 Symbol* obj_class = ss.as_symbol();
379 k = SystemDictionary::resolve_instance_class_or_null(obj_class,
380 class_loader,
381 protection_domain,
382 CHECK_NULL);
383 if (k != nullptr) {
384 k = k->array_klass(ndims, CHECK_NULL);
385 }
386 } else {
387 k = Universe::typeArrayKlass(t);
388 k = k->array_klass(ndims, CHECK_NULL);
389 }
390 return k;
391 }
392
393 static inline void log_circularity_error(Symbol* name, PlaceholderEntry* probe) {
394 LogTarget(Debug, class, load, placeholders) lt;
395 if (lt.is_enabled()) {
396 ResourceMark rm;
397 LogStream ls(lt);
398 ls.print("ClassCircularityError detected for placeholder entry %s", name->as_C_string());
399 probe->print_on(&ls);
400 ls.cr();
401 }
402 }
403
404 // Must be called for any superclass or superinterface resolution
405 // during class definition to allow class circularity checking
406 // superinterface callers:
407 // parse_interfaces - from defineClass
408 // superclass callers:
409 // ClassFileParser - from defineClass
410 // load_shared_class - while loading a class from shared archive
411 // resolve_instance_class_or_null:
412 // via: handle_parallel_super_load
413 // when resolving a class that has an existing placeholder with
414 // a saved superclass [i.e. a defineClass is currently in progress]
415 // If another thread is trying to resolve the class, it must do
416 // superclass checks on its own thread to catch class circularity and
417 // to avoid deadlock.
418 //
419 // resolve_with_circularity_detection adds a DETECT_CIRCULARITY placeholder to the placeholder table before calling
420 // resolve_instance_class_or_null. ClassCircularityError is detected when a DETECT_CIRCULARITY or LOAD_INSTANCE
421 // placeholder for the same thread, class, classloader is found.
422 // This can be seen with logging option: -Xlog:class+load+placeholders=debug.
423 //
424 InstanceKlass* SystemDictionary::resolve_with_circularity_detection(Symbol* class_name,
425 Symbol* next_name,
426 Handle class_loader,
427 Handle protection_domain,
428 bool is_superclass,
429 TRAPS) {
430
431 assert(next_name != nullptr, "null superclass for resolving");
432 assert(!Signature::is_array(next_name), "invalid superclass name");
433 #if INCLUDE_CDS
434 if (CDSConfig::is_dumping_static_archive()) {
435 // Special processing for handling UNREGISTERED shared classes.
436 InstanceKlass* k = SystemDictionaryShared::lookup_super_for_unregistered_class(class_name,
437 next_name, is_superclass);
438 if (k) {
439 return k;
440 }
441 }
442 #endif // INCLUDE_CDS
443
444 // If class_name is already loaded, just return the superclass or superinterface.
445 // Make sure there's a placeholder for the class_name before resolving.
446 // This is used as a claim that this thread is currently loading superclass/classloader
447 // and for ClassCircularity checks.
448
449 ClassLoaderData* loader_data = class_loader_data(class_loader);
450 Dictionary* dictionary = loader_data->dictionary();
451
452 // can't throw error holding a lock
453 bool throw_circularity_error = false;
454 {
455 MutexLocker mu(THREAD, SystemDictionary_lock);
456 InstanceKlass* klassk = dictionary->find_class(THREAD, class_name);
457 InstanceKlass* quicksuperk;
458 // To support parallel loading: if class is done loading, just return the superclass
459 // if the next_name matches class->super()->name() and if the class loaders match.
460 // Otherwise, a LinkageError will be thrown later.
461 if (klassk != nullptr && is_superclass &&
462 ((quicksuperk = klassk->java_super()) != nullptr) &&
463 ((quicksuperk->name() == next_name) &&
464 (quicksuperk->class_loader() == class_loader()))) {
465 return quicksuperk;
466 } else {
467 // Must check ClassCircularity before checking if superclass is already loaded.
468 PlaceholderEntry* probe = PlaceholderTable::get_entry(class_name, loader_data);
469 if (probe && probe->check_seen_thread(THREAD, PlaceholderTable::DETECT_CIRCULARITY)) {
470 log_circularity_error(class_name, probe);
471 throw_circularity_error = true;
472 }
473 }
474
475 if (!throw_circularity_error) {
476 // Be careful not to exit resolve_with_circularity_detection without removing this placeholder.
477 PlaceholderEntry* newprobe = PlaceholderTable::find_and_add(class_name,
478 loader_data,
479 PlaceholderTable::DETECT_CIRCULARITY,
480 next_name, THREAD);
481 }
482 }
483
484 if (throw_circularity_error) {
485 ResourceMark rm(THREAD);
486 THROW_MSG_NULL(vmSymbols::java_lang_ClassCircularityError(), class_name->as_C_string());
487 }
488
489 // Resolve the superclass or superinterface, check results on return
490 InstanceKlass* superk =
491 SystemDictionary::resolve_instance_class_or_null(next_name,
492 class_loader,
493 protection_domain,
494 THREAD);
495
496 // Clean up placeholder entry.
497 {
498 MutexLocker mu(THREAD, SystemDictionary_lock);
499 PlaceholderTable::find_and_remove(class_name, loader_data, PlaceholderTable::DETECT_CIRCULARITY, THREAD);
500 SystemDictionary_lock->notify_all();
501 }
502
503 // Check for pending exception or null superk, and throw exception
504 if (HAS_PENDING_EXCEPTION || superk == nullptr) {
505 handle_resolution_exception(next_name, true, CHECK_NULL);
506 }
507
508 return superk;
509 }
510
511 // If the class in is in the placeholder table, class loading is in progress.
512 // For cases where the application changes threads to load classes, it
513 // is critical to ClassCircularity detection that we try loading
514 // the superclass on the new thread internally, so we do parallel
515 // superclass loading here. This avoids deadlock for ClassCircularity
516 // detection for parallelCapable class loaders that lock on a per-class lock.
517 static void handle_parallel_super_load(Symbol* name,
518 Symbol* superclassname,
519 Handle class_loader,
520 Handle protection_domain, TRAPS) {
521
522 // The result superk is not used; resolve_with_circularity_detection is called for circularity check only.
523 // This passes true to is_superclass even though it might not be the super class in order to perform the
524 // optimization anyway.
525 Klass* superk = SystemDictionary::resolve_with_circularity_detection(name,
526 superclassname,
527 class_loader,
528 protection_domain,
529 true,
530 CHECK);
531 }
532
533 // Bootstrap and non-parallel capable class loaders use the LOAD_INSTANCE placeholder to
534 // wait for parallel class loading and/or to check for circularity error for Xcomp when loading.
535 static bool needs_load_placeholder(Handle class_loader) {
536 return class_loader.is_null() || !is_parallelCapable(class_loader);
537 }
538
539 // Check for other threads loading this class either to throw CCE or wait in the case of the boot loader.
540 static InstanceKlass* handle_parallel_loading(JavaThread* current,
541 Symbol* name,
542 ClassLoaderData* loader_data,
543 bool must_wait_for_class_loading,
544 bool* throw_circularity_error) {
545 PlaceholderEntry* oldprobe = PlaceholderTable::get_entry(name, loader_data);
546 if (oldprobe != nullptr) {
547 // -Xcomp calls load_signature_classes which might result in loading
548 // a class that's already in the process of loading, so we detect CCE here also.
549 // Only need check_seen_thread once, not on each loop
550 if (oldprobe->check_seen_thread(current, PlaceholderTable::LOAD_INSTANCE)) {
551 log_circularity_error(name, oldprobe);
552 *throw_circularity_error = true;
553 return nullptr;
554 } else if (must_wait_for_class_loading) {
555 // Wait until the first thread has finished loading this class. Also wait until all the
556 // threads trying to load its superclass have removed their placeholders.
557 while (oldprobe != nullptr &&
558 (oldprobe->instance_load_in_progress() || oldprobe->circularity_detection_in_progress())) {
559
560 // LOAD_INSTANCE placeholders are used to implement parallel capable class loading
561 // for the bootclass loader.
562 SystemDictionary_lock->wait();
563
564 // Check if classloading completed while we were waiting
565 InstanceKlass* check = loader_data->dictionary()->find_class(current, name);
566 if (check != nullptr) {
567 // Klass is already loaded, so just return it
568 return check;
569 }
570 // check if other thread failed to load and cleaned up
571 oldprobe = PlaceholderTable::get_entry(name, loader_data);
572 }
573 }
574 }
575 return nullptr;
576 }
577
578 void SystemDictionary::post_class_load_event(EventClassLoad* event, const InstanceKlass* k, const ClassLoaderData* init_cld) {
579 assert(event != nullptr, "invariant");
580 assert(k != nullptr, "invariant");
581 event->set_loadedClass(k);
582 event->set_definingClassLoader(k->class_loader_data());
583 event->set_initiatingClassLoader(init_cld);
584 event->commit();
585 }
586
587 // SystemDictionary::resolve_instance_class_or_null is the main function for class name resolution.
588 // After checking if the InstanceKlass already exists, it checks for ClassCircularityError and
589 // whether the thread must wait for loading in parallel. It eventually calls load_instance_class,
590 // which will load the class via the bootstrap loader or call ClassLoader.loadClass().
591 // This can return null, an exception or an InstanceKlass.
592 InstanceKlass* SystemDictionary::resolve_instance_class_or_null(Symbol* name,
593 Handle class_loader,
594 Handle protection_domain,
595 TRAPS) {
596 // name must be in the form of "java/lang/Object" -- cannot be "Ljava/lang/Object;"
597 DEBUG_ONLY(ResourceMark rm(THREAD));
598 assert(name != nullptr && !Signature::is_array(name) &&
599 !Signature::has_envelope(name), "invalid class name: %s", name == nullptr ? "nullptr" : name->as_C_string());
600
601 EventClassLoad class_load_start_event;
602
603 HandleMark hm(THREAD);
604
605 // Fix for 4474172; see evaluation for more details
606 class_loader = Handle(THREAD, java_lang_ClassLoader::non_reflection_class_loader(class_loader()));
607 ClassLoaderData* loader_data = register_loader(class_loader);
608 Dictionary* dictionary = loader_data->dictionary();
609
610 // Do lookup to see if class already exists and the protection domain
611 // has the right access.
612 // This call uses find which checks protection domain already matches
613 // All subsequent calls use find_class, and set loaded_class so that
614 // before we return a result, we call out to java to check for valid protection domain.
615 InstanceKlass* probe = dictionary->find(THREAD, name, protection_domain);
616 if (probe != nullptr) return probe;
617
618 // Non-bootstrap class loaders will call out to class loader and
619 // define via jvm/jni_DefineClass which will acquire the
620 // class loader object lock to protect against multiple threads
621 // defining the class in parallel by accident.
622 // This lock must be acquired here so the waiter will find
623 // any successful result in the SystemDictionary and not attempt
624 // the define.
625 // ParallelCapable class loaders and the bootstrap classloader
626 // do not acquire lock here.
627 Handle lockObject = get_loader_lock_or_null(class_loader);
628 ObjectLocker ol(lockObject, THREAD);
629
630 bool circularity_detection_in_progress = false;
631 InstanceKlass* loaded_class = nullptr;
632 SymbolHandle superclassname; // Keep alive while loading in parallel thread.
633
634 guarantee(THREAD->can_call_java(),
635 "can not load classes with compiler thread: class=%s, classloader=%s",
636 name->as_C_string(),
637 class_loader.is_null() ? "null" : class_loader->klass()->name()->as_C_string());
638
639 // Check again (after locking) if the class already exists in SystemDictionary
640 {
641 MutexLocker mu(THREAD, SystemDictionary_lock);
642 InstanceKlass* check = dictionary->find_class(THREAD, name);
643 if (check != nullptr) {
644 // InstanceKlass is already loaded, but we still need to check protection domain below.
645 loaded_class = check;
646 } else {
647 PlaceholderEntry* placeholder = PlaceholderTable::get_entry(name, loader_data);
648 if (placeholder != nullptr && placeholder->circularity_detection_in_progress()) {
649 circularity_detection_in_progress = true;
650 superclassname = placeholder->next_klass_name();
651 assert(superclassname != nullptr, "superclass has to have a name");
652 }
653 }
654 }
655
656 // If the class is in the placeholder table with super_class set,
657 // handle superclass loading in progress.
658 if (circularity_detection_in_progress) {
659 handle_parallel_super_load(name, superclassname,
660 class_loader,
661 protection_domain,
662 CHECK_NULL);
663 }
664
665 bool throw_circularity_error = false;
666 if (loaded_class == nullptr) {
667 bool load_placeholder_added = false;
668
669 // Add placeholder entry to record loading instance class
670 // case 1. Bootstrap classloader
671 // This classloader supports parallelism at the classloader level
672 // but only allows a single thread to load a class/classloader pair.
673 // The LOAD_INSTANCE placeholder is the mechanism for mutual exclusion.
674 // case 2. parallelCapable user level classloaders
675 // These class loaders lock a per-class object lock when ClassLoader.loadClass()
676 // is called. A LOAD_INSTANCE placeholder isn't used for mutual exclusion.
677 // case 3. traditional classloaders that rely on the classloader object lock
678 // There should be no need for need for LOAD_INSTANCE for mutual exclusion,
679 // except the LOAD_INSTANCE placeholder is used to detect CCE for -Xcomp.
680 // TODO: should also be used to detect CCE for parallel capable class loaders but it's not.
681 {
682 MutexLocker mu(THREAD, SystemDictionary_lock);
683 if (needs_load_placeholder(class_loader)) {
684 loaded_class = handle_parallel_loading(THREAD,
685 name,
686 loader_data,
687 class_loader.is_null(),
688 &throw_circularity_error);
689 }
690
691 // Recheck if the class has been loaded for all class loader cases and
692 // add a LOAD_INSTANCE placeholder while holding the SystemDictionary_lock.
693 if (!throw_circularity_error && loaded_class == nullptr) {
694 InstanceKlass* check = dictionary->find_class(THREAD, name);
695 if (check != nullptr) {
696 loaded_class = check;
697 } else if (needs_load_placeholder(class_loader)) {
698 // Add the LOAD_INSTANCE token. Threads will wait on loading to complete for this thread.
699 PlaceholderEntry* newprobe = PlaceholderTable::find_and_add(name, loader_data,
700 PlaceholderTable::LOAD_INSTANCE,
701 nullptr,
702 THREAD);
703 load_placeholder_added = true;
704 }
705 }
706 }
707
708 // Must throw error outside of owning lock
709 if (throw_circularity_error) {
710 assert(!HAS_PENDING_EXCEPTION && !load_placeholder_added, "circularity error cleanup");
711 ResourceMark rm(THREAD);
712 THROW_MSG_NULL(vmSymbols::java_lang_ClassCircularityError(), name->as_C_string());
713 }
714
715 // Be careful when modifying this code: once you have run
716 // PlaceholderTable::find_and_add(PlaceholderTable::LOAD_INSTANCE),
717 // you need to find_and_remove it before returning.
718 // So be careful to not exit with a CHECK_ macro between these calls.
719
720 if (loaded_class == nullptr) {
721 // Do actual loading
722 loaded_class = load_instance_class(name, class_loader, THREAD);
723 }
724
725 if (load_placeholder_added) {
726 // clean up placeholder entries for LOAD_INSTANCE success or error
727 // This brackets the SystemDictionary updates for both defining
728 // and initiating loaders
729 MutexLocker mu(THREAD, SystemDictionary_lock);
730 PlaceholderTable::find_and_remove(name, loader_data, PlaceholderTable::LOAD_INSTANCE, THREAD);
731 SystemDictionary_lock->notify_all();
732 }
733 }
734
735 if (HAS_PENDING_EXCEPTION || loaded_class == nullptr) {
736 return nullptr;
737 }
738
739 if (class_load_start_event.should_commit()) {
740 post_class_load_event(&class_load_start_event, loaded_class, loader_data);
741 }
742
743 // Make sure we have the right class in the dictionary
744 DEBUG_ONLY(verify_dictionary_entry(name, loaded_class));
745
746 if (protection_domain() != nullptr) {
747 // A SecurityManager (if installed) may prevent this protection_domain from accessing loaded_class
748 // by throwing a SecurityException.
749 dictionary->check_package_access(loaded_class, class_loader, protection_domain, CHECK_NULL);
750 }
751
752 return loaded_class;
753 }
754
755
756 // This routine does not lock the system dictionary.
757 //
758 // Since readers don't hold a lock, we must make sure that system
759 // dictionary entries are added to in a safe way (all links must
760 // be updated in an MT-safe manner). All entries are removed during class
761 // unloading, when this class loader is no longer referenced.
762 //
763 // Callers should be aware that an entry could be added just after
764 // Dictionary is read here, so the caller will not see
765 // the new entry.
766
767 InstanceKlass* SystemDictionary::find_instance_klass(Thread* current,
768 Symbol* class_name,
769 Handle class_loader,
770 Handle protection_domain) {
771
772 // The result of this call should be consistent with the result
773 // of the call to resolve_instance_class_or_null().
774 // See evaluation 6790209 and 4474172 for more details.
775 oop class_loader_oop = java_lang_ClassLoader::non_reflection_class_loader(class_loader());
776 ClassLoaderData* loader_data = ClassLoaderData::class_loader_data_or_null(class_loader_oop);
777
778 if (loader_data == nullptr) {
779 // If the ClassLoaderData has not been setup,
780 // then the class loader has no entries in the dictionary.
781 return nullptr;
782 }
783
784 Dictionary* dictionary = loader_data->dictionary();
785 return dictionary->find(current, class_name, protection_domain);
786 }
787
788 // Look for a loaded instance or array klass by name. Do not do any loading.
789 // return null in case of error.
790 Klass* SystemDictionary::find_instance_or_array_klass(Thread* current,
791 Symbol* class_name,
792 Handle class_loader,
793 Handle protection_domain) {
794 Klass* k = nullptr;
795 assert(class_name != nullptr, "class name must be non nullptr");
796
797 if (Signature::is_array(class_name)) {
798 // The name refers to an array. Parse the name.
799 // dimension and object_key in FieldArrayInfo are assigned as a
800 // side-effect of this call
801 SignatureStream ss(class_name, false);
802 int ndims = ss.skip_array_prefix(); // skip all '['s
803 BasicType t = ss.type();
804 if (t != T_OBJECT) {
805 k = Universe::typeArrayKlass(t);
806 } else {
807 k = SystemDictionary::find_instance_klass(current, ss.as_symbol(), class_loader, protection_domain);
808 }
809 if (k != nullptr) {
810 k = k->array_klass_or_null(ndims);
811 }
812 } else {
813 k = find_instance_klass(current, class_name, class_loader, protection_domain);
814 }
815 return k;
816 }
817
818 // Note: this method is much like resolve_class_from_stream, but
819 // does not publish the classes in the SystemDictionary.
820 // Handles Lookup.defineClass hidden.
821 InstanceKlass* SystemDictionary::resolve_hidden_class_from_stream(
822 ClassFileStream* st,
823 Symbol* class_name,
824 Handle class_loader,
825 const ClassLoadInfo& cl_info,
826 TRAPS) {
827
828 EventClassLoad class_load_start_event;
829 ClassLoaderData* loader_data;
830
831 // - for hidden classes that are not strong: create a new CLD that has a class holder and
832 // whose loader is the Lookup class's loader.
833 // - for hidden class: add the class to the Lookup class's loader's CLD.
834 assert (cl_info.is_hidden(), "only used for hidden classes");
835 bool create_mirror_cld = !cl_info.is_strong_hidden();
836 loader_data = register_loader(class_loader, create_mirror_cld);
837
838 assert(st != nullptr, "invariant");
839 assert(st->need_verify(), "invariant");
840
841 // Parse stream and create a klass.
842 InstanceKlass* k = KlassFactory::create_from_stream(st,
843 class_name,
844 loader_data,
845 cl_info,
846 CHECK_NULL);
847 assert(k != nullptr, "no klass created");
848
849 // Hidden classes that are not strong must update ClassLoaderData holder
850 // so that they can be unloaded when the mirror is no longer referenced.
851 if (!cl_info.is_strong_hidden()) {
852 k->class_loader_data()->initialize_holder(Handle(THREAD, k->java_mirror()));
853 }
854
855 // Add to class hierarchy, and do possible deoptimizations.
856 k->add_to_hierarchy(THREAD);
857 // But, do not add to dictionary.
858
859 k->link_class(CHECK_NULL);
860
861 // notify jvmti
862 if (JvmtiExport::should_post_class_load()) {
863 JvmtiExport::post_class_load(THREAD, k);
864 }
865 if (class_load_start_event.should_commit()) {
866 post_class_load_event(&class_load_start_event, k, loader_data);
867 }
868
869 return k;
870 }
871
872 // Add a klass to the system from a stream (called by jni_DefineClass and
873 // JVM_DefineClass).
874 // Note: class_name can be null. In that case we do not know the name of
875 // the class until we have parsed the stream.
876 // This function either returns an InstanceKlass or throws an exception. It does
877 // not return null without a pending exception.
878 InstanceKlass* SystemDictionary::resolve_class_from_stream(
879 ClassFileStream* st,
880 Symbol* class_name,
881 Handle class_loader,
882 const ClassLoadInfo& cl_info,
883 TRAPS) {
884
885 HandleMark hm(THREAD);
886
887 ClassLoaderData* loader_data = register_loader(class_loader);
888
889 // Classloaders that support parallelism, e.g. bootstrap classloader,
890 // do not acquire lock here
891 Handle lockObject = get_loader_lock_or_null(class_loader);
892 ObjectLocker ol(lockObject, THREAD);
893
894 // Parse the stream and create a klass.
895 // Note that we do this even though this klass might
896 // already be present in the SystemDictionary, otherwise we would not
897 // throw potential ClassFormatErrors.
898 InstanceKlass* k = nullptr;
899
900 #if INCLUDE_CDS
901 if (!CDSConfig::is_dumping_static_archive()) {
902 k = SystemDictionaryShared::lookup_from_stream(class_name,
903 class_loader,
904 cl_info.protection_domain(),
905 st,
906 CHECK_NULL);
907 }
908 #endif
909
910 if (k == nullptr) {
911 k = KlassFactory::create_from_stream(st, class_name, loader_data, cl_info, CHECK_NULL);
912 }
913
914 assert(k != nullptr, "no klass created");
915 Symbol* h_name = k->name();
916 assert(class_name == nullptr || class_name == h_name, "name mismatch");
917
918 // Add class just loaded
919 // If a class loader supports parallel classloading, handle parallel define requests.
920 // find_or_define_instance_class may return a different InstanceKlass,
921 // in which case the old k would be deallocated
922 if (is_parallelCapable(class_loader)) {
923 k = find_or_define_instance_class(h_name, class_loader, k, CHECK_NULL);
924 } else {
925 define_instance_class(k, class_loader, THREAD);
926
927 // If defining the class throws an exception register 'k' for cleanup.
928 if (HAS_PENDING_EXCEPTION) {
929 assert(k != nullptr, "Must have an instance klass here!");
930 loader_data->add_to_deallocate_list(k);
931 return nullptr;
932 }
933 }
934
935 // Make sure we have an entry in the SystemDictionary on success
936 DEBUG_ONLY(verify_dictionary_entry(h_name, k));
937
938 return k;
939 }
940
941 InstanceKlass* SystemDictionary::resolve_from_stream(ClassFileStream* st,
942 Symbol* class_name,
943 Handle class_loader,
944 const ClassLoadInfo& cl_info,
945 TRAPS) {
946 if (cl_info.is_hidden()) {
947 return resolve_hidden_class_from_stream(st, class_name, class_loader, cl_info, CHECK_NULL);
948 } else {
949 return resolve_class_from_stream(st, class_name, class_loader, cl_info, CHECK_NULL);
950 }
951 }
952
953
954 #if INCLUDE_CDS
955 // Check if a shared class can be loaded by the specific classloader.
956 bool SystemDictionary::is_shared_class_visible(Symbol* class_name,
957 InstanceKlass* ik,
958 PackageEntry* pkg_entry,
959 Handle class_loader) {
960 assert(!CDSConfig::module_patching_disables_cds(), "Cannot use CDS");
961
962 // (1) Check if we are loading into the same loader as in dump time.
963
964 if (ik->is_shared_boot_class()) {
965 if (class_loader() != nullptr) {
966 return false;
967 }
968 } else if (ik->is_shared_platform_class()) {
969 if (class_loader() != java_platform_loader()) {
970 return false;
971 }
972 } else if (ik->is_shared_app_class()) {
973 if (class_loader() != java_system_loader()) {
974 return false;
975 }
976 } else {
977 // ik was loaded by a custom loader during dump time
978 if (class_loader_data(class_loader)->is_builtin_class_loader_data()) {
979 return false;
980 } else {
981 return true;
982 }
983 }
984
985 // (2) Check if we are loading into the same module from the same location as in dump time.
986
987 if (CDSConfig::is_using_optimized_module_handling()) {
988 // Class visibility has not changed between dump time and run time, so a class
989 // that was visible (and thus archived) during dump time is always visible during runtime.
990 assert(SystemDictionary::is_shared_class_visible_impl(class_name, ik, pkg_entry, class_loader),
991 "visibility cannot change between dump time and runtime");
992 return true;
993 }
994 return is_shared_class_visible_impl(class_name, ik, pkg_entry, class_loader);
995 }
996
997 bool SystemDictionary::is_shared_class_visible_impl(Symbol* class_name,
998 InstanceKlass* ik,
999 PackageEntry* pkg_entry,
1000 Handle class_loader) {
1001 int scp_index = ik->shared_classpath_index();
1002 assert(!ik->is_shared_unregistered_class(), "this function should be called for built-in classes only");
1003 assert(scp_index >= 0, "must be");
1004 SharedClassPathEntry* scp_entry = FileMapInfo::shared_path(scp_index);
1005 if (!Universe::is_module_initialized()) {
1006 assert(scp_entry != nullptr, "must be");
1007 // At this point, no modules have been defined yet. KlassSubGraphInfo::check_allowed_klass()
1008 // has restricted the classes can be loaded at this step to be only:
1009 // [1] scp_entry->is_modules_image(): classes in java.base, or,
1010 // [2] HeapShared::is_a_test_class_in_unnamed_module(ik): classes in bootstrap/unnamed module
1011 assert(scp_entry->is_modules_image() || HeapShared::is_a_test_class_in_unnamed_module(ik),
1012 "only these classes can be loaded before the module system is initialized");
1013 assert(class_loader.is_null(), "sanity");
1014 return true;
1015 }
1016
1017 if (pkg_entry == nullptr) {
1018 // We might have looked up pkg_entry before the module system was initialized.
1019 // Need to reload it now.
1020 TempNewSymbol pkg_name = ClassLoader::package_from_class_name(class_name);
1021 if (pkg_name != nullptr) {
1022 pkg_entry = class_loader_data(class_loader)->packages()->lookup_only(pkg_name);
1023 }
1024 }
1025
1026 ModuleEntry* mod_entry = (pkg_entry == nullptr) ? nullptr : pkg_entry->module();
1027 bool should_be_in_named_module = (mod_entry != nullptr && mod_entry->is_named());
1028 bool was_archived_from_named_module = scp_entry->in_named_module();
1029 bool visible;
1030
1031 if (was_archived_from_named_module) {
1032 if (should_be_in_named_module) {
1033 // Is the module loaded from the same location as during dump time?
1034 visible = mod_entry->shared_path_index() == scp_index;
1035 if (visible) {
1036 assert(!CDSConfig::module_patching_disables_cds(), "Cannot use CDS");
1037 }
1038 } else {
1039 // During dump time, this class was in a named module, but at run time, this class should be
1040 // in an unnamed module.
1041 visible = false;
1042 }
1043 } else {
1044 if (should_be_in_named_module) {
1045 // During dump time, this class was in an unnamed, but at run time, this class should be
1046 // in a named module.
1047 visible = false;
1048 } else {
1049 visible = true;
1050 }
1051 }
1052
1053 return visible;
1054 }
1055
1056 bool SystemDictionary::check_shared_class_super_type(InstanceKlass* klass, InstanceKlass* super_type,
1057 Handle class_loader, Handle protection_domain,
1058 bool is_superclass, TRAPS) {
1059 assert(super_type->is_shared(), "must be");
1060
1061 // Quick check if the super type has been already loaded.
1062 // + Don't do it for unregistered classes -- they can be unloaded so
1063 // super_type->class_loader_data() could be stale.
1064 // + Don't check if loader data is null, ie. the super_type isn't fully loaded.
1065 if (!super_type->is_shared_unregistered_class() && super_type->class_loader_data() != nullptr) {
1066 // Check if the superclass is loaded by the current class_loader
1067 Symbol* name = super_type->name();
1068 InstanceKlass* check = find_instance_klass(THREAD, name, class_loader, protection_domain);
1069 if (check == super_type) {
1070 return true;
1071 }
1072 }
1073
1074 Klass *found = resolve_with_circularity_detection(klass->name(), super_type->name(),
1075 class_loader, protection_domain, is_superclass, CHECK_false);
1076 if (found == super_type) {
1077 return true;
1078 } else {
1079 // The dynamically resolved super type is not the same as the one we used during dump time,
1080 // so we cannot use the class.
1081 return false;
1082 }
1083 }
1084
1085 bool SystemDictionary::check_shared_class_super_types(InstanceKlass* ik, Handle class_loader,
1086 Handle protection_domain, TRAPS) {
1087 // Check the superclass and interfaces. They must be the same
1088 // as in dump time, because the layout of <ik> depends on
1089 // the specific layout of ik->super() and ik->local_interfaces().
1090 //
1091 // If unexpected superclass or interfaces are found, we cannot
1092 // load <ik> from the shared archive.
1093
1094 if (ik->super() != nullptr) {
1095 bool check_super = check_shared_class_super_type(ik, InstanceKlass::cast(ik->super()),
1096 class_loader, protection_domain, true,
1097 CHECK_false);
1098 if (!check_super) {
1099 return false;
1100 }
1101 }
1102
1103 Array<InstanceKlass*>* interfaces = ik->local_interfaces();
1104 int num_interfaces = interfaces->length();
1105 for (int index = 0; index < num_interfaces; index++) {
1106 bool check_interface = check_shared_class_super_type(ik, interfaces->at(index), class_loader, protection_domain, false,
1107 CHECK_false);
1108 if (!check_interface) {
1109 return false;
1110 }
1111 }
1112
1113 return true;
1114 }
1115
1116 InstanceKlass* SystemDictionary::load_shared_lambda_proxy_class(InstanceKlass* ik,
1117 Handle class_loader,
1118 Handle protection_domain,
1119 PackageEntry* pkg_entry,
1120 TRAPS) {
1121 InstanceKlass* shared_nest_host = SystemDictionaryShared::get_shared_nest_host(ik);
1122 assert(shared_nest_host->is_shared(), "nest host must be in CDS archive");
1123 Symbol* cn = shared_nest_host->name();
1124 Klass *s = resolve_or_fail(cn, class_loader, protection_domain, true, CHECK_NULL);
1125 if (s != shared_nest_host) {
1126 // The dynamically resolved nest_host is not the same as the one we used during dump time,
1127 // so we cannot use ik.
1128 return nullptr;
1129 } else {
1130 assert(s->is_shared(), "must be");
1131 }
1132
1133 InstanceKlass* loaded_ik = load_shared_class(ik, class_loader, protection_domain, nullptr, pkg_entry, CHECK_NULL);
1134
1135 if (loaded_ik != nullptr) {
1136 assert(shared_nest_host->is_same_class_package(ik),
1137 "lambda proxy class and its nest host must be in the same package");
1138 // The lambda proxy class and its nest host have the same class loader and class loader data,
1139 // as verified in SystemDictionaryShared::add_lambda_proxy_class()
1140 assert(shared_nest_host->class_loader() == class_loader(), "mismatched class loader");
1141 assert(shared_nest_host->class_loader_data() == class_loader_data(class_loader), "mismatched class loader data");
1142 ik->set_nest_host(shared_nest_host);
1143 }
1144
1145 return loaded_ik;
1146 }
1147
1148 InstanceKlass* SystemDictionary::load_shared_class(InstanceKlass* ik,
1149 Handle class_loader,
1150 Handle protection_domain,
1151 const ClassFileStream *cfs,
1152 PackageEntry* pkg_entry,
1153 TRAPS) {
1154 assert(ik != nullptr, "sanity");
1155 assert(!ik->is_unshareable_info_restored(), "shared class can be restored only once");
1156 assert(Atomic::add(&ik->_shared_class_load_count, 1) == 1, "shared class loaded more than once");
1157 Symbol* class_name = ik->name();
1158
1159 if (!is_shared_class_visible(class_name, ik, pkg_entry, class_loader)) {
1160 ik->set_shared_loading_failed();
1161 return nullptr;
1162 }
1163
1164 bool check = check_shared_class_super_types(ik, class_loader, protection_domain, CHECK_NULL);
1165 if (!check) {
1166 ik->set_shared_loading_failed();
1167 return nullptr;
1168 }
1169
1170 if (ik->has_inline_type_fields()) {
1171 for (AllFieldStream fs(ik); !fs.done(); fs.next()) {
1172 if (fs.access_flags().is_static()) continue;
1173 Symbol* sig = fs.signature();
1174 if (fs.is_null_free_inline_type()) {
1175 // Pre-load inline class
1176 TempNewSymbol name = Signature::strip_envelope(sig);
1177 Klass* real_k = SystemDictionary::resolve_with_circularity_detection_or_fail(ik->name(), name,
1178 class_loader, protection_domain, false, CHECK_NULL);
1179 Klass* k = ik->get_inline_type_field_klass_or_null(fs.index());
1180 if (real_k != k) {
1181 // oops, the app has substituted a different version of k!
1182 return nullptr;
1183 }
1184 } else if (Signature::has_envelope(sig)) {
1185 TempNewSymbol name = Signature::strip_envelope(sig);
1186 if (name != ik->name() && ik->is_class_in_loadable_descriptors_attribute(name)) {
1187 Klass* real_k = SystemDictionary::resolve_with_circularity_detection_or_fail(ik->name(), name,
1188 class_loader, protection_domain, false, THREAD);
1189 if (HAS_PENDING_EXCEPTION) {
1190 CLEAR_PENDING_EXCEPTION;
1191 }
1192 Klass* k = ik->get_inline_type_field_klass_or_null(fs.index());
1193 if (real_k != k) {
1194 // oops, the app has substituted a different version of k!
1195 return nullptr;
1196 }
1197 }
1198 }
1199 }
1200 }
1201
1202 InstanceKlass* new_ik = nullptr;
1203 // CFLH check is skipped for VM hidden classes (see KlassFactory::create_from_stream).
1204 // It will be skipped for shared VM hidden lambda proxy classes.
1205 if (!SystemDictionaryShared::is_hidden_lambda_proxy(ik)) {
1206 new_ik = KlassFactory::check_shared_class_file_load_hook(
1207 ik, class_name, class_loader, protection_domain, cfs, CHECK_NULL);
1208 }
1209 if (new_ik != nullptr) {
1210 // The class is changed by CFLH. Return the new class. The shared class is
1211 // not used.
1212 return new_ik;
1213 }
1214
1215 // Adjust methods to recover missing data. They need addresses for
1216 // interpreter entry points and their default native method address
1217 // must be reset.
1218
1219 // Shared classes are all currently loaded by either the bootstrap or
1220 // internal parallel class loaders, so this will never cause a deadlock
1221 // on a custom class loader lock.
1222 // Since this class is already locked with parallel capable class
1223 // loaders, including the bootstrap loader via the placeholder table,
1224 // this lock is currently a nop.
1225
1226 ClassLoaderData* loader_data = class_loader_data(class_loader);
1227 {
1228 HandleMark hm(THREAD);
1229 Handle lockObject = get_loader_lock_or_null(class_loader);
1230 ObjectLocker ol(lockObject, THREAD);
1231 // prohibited package check assumes all classes loaded from archive call
1232 // restore_unshareable_info which calls ik->set_package()
1233 ik->restore_unshareable_info(loader_data, protection_domain, pkg_entry, CHECK_NULL);
1234 }
1235
1236 load_shared_class_misc(ik, loader_data);
1237
1238 return ik;
1239 }
1240
1241 void SystemDictionary::load_shared_class_misc(InstanceKlass* ik, ClassLoaderData* loader_data) {
1242 ik->print_class_load_logging(loader_data, nullptr, nullptr);
1243
1244 // For boot loader, ensure that GetSystemPackage knows that a class in this
1245 // package was loaded.
1246 if (loader_data->is_the_null_class_loader_data()) {
1247 s2 path_index = ik->shared_classpath_index();
1248 ik->set_classpath_index(path_index);
1249 }
1250
1251 // notify a class loaded from shared object
1252 ClassLoadingService::notify_class_loaded(ik, true /* shared class */);
1253 }
1254
1255 #endif // INCLUDE_CDS
1256
1257 InstanceKlass* SystemDictionary::load_instance_class_impl(Symbol* class_name, Handle class_loader, TRAPS) {
1258
1259 if (class_loader.is_null()) {
1260 ResourceMark rm(THREAD);
1261 PackageEntry* pkg_entry = nullptr;
1262 bool search_only_bootloader_append = false;
1263
1264 // Find the package in the boot loader's package entry table.
1265 TempNewSymbol pkg_name = ClassLoader::package_from_class_name(class_name);
1266 if (pkg_name != nullptr) {
1267 pkg_entry = class_loader_data(class_loader)->packages()->lookup_only(pkg_name);
1268 }
1269
1270 // Prior to attempting to load the class, enforce the boot loader's
1271 // visibility boundaries.
1272 if (!Universe::is_module_initialized()) {
1273 // During bootstrapping, prior to module initialization, any
1274 // class attempting to be loaded must be checked against the
1275 // java.base packages in the boot loader's PackageEntryTable.
1276 // No class outside of java.base is allowed to be loaded during
1277 // this bootstrapping window.
1278 if (pkg_entry == nullptr || pkg_entry->in_unnamed_module()) {
1279 // Class is either in the unnamed package or in
1280 // a named package within the unnamed module. Either
1281 // case is outside of java.base, do not attempt to
1282 // load the class post java.base definition. If
1283 // java.base has not been defined, let the class load
1284 // and its package will be checked later by
1285 // ModuleEntryTable::verify_javabase_packages.
1286 if (ModuleEntryTable::javabase_defined()) {
1287 return nullptr;
1288 }
1289 } else {
1290 // Check that the class' package is defined within java.base.
1291 ModuleEntry* mod_entry = pkg_entry->module();
1292 Symbol* mod_entry_name = mod_entry->name();
1293 if (mod_entry_name->fast_compare(vmSymbols::java_base()) != 0) {
1294 return nullptr;
1295 }
1296 }
1297 } else {
1298 // After the module system has been initialized, check if the class'
1299 // package is in a module defined to the boot loader.
1300 if (pkg_name == nullptr || pkg_entry == nullptr || pkg_entry->in_unnamed_module()) {
1301 // Class is either in the unnamed package, in a named package
1302 // within a module not defined to the boot loader or in a
1303 // a named package within the unnamed module. In all cases,
1304 // limit visibility to search for the class only in the boot
1305 // loader's append path.
1306 if (!ClassLoader::has_bootclasspath_append()) {
1307 // If there is no bootclasspath append entry, no need to continue
1308 // searching.
1309 return nullptr;
1310 }
1311 search_only_bootloader_append = true;
1312 }
1313 }
1314
1315 // Prior to bootstrapping's module initialization, never load a class outside
1316 // of the boot loader's module path
1317 assert(Universe::is_module_initialized() ||
1318 !search_only_bootloader_append,
1319 "Attempt to load a class outside of boot loader's module path");
1320
1321 // Search for classes in the CDS archive.
1322 InstanceKlass* k = nullptr;
1323
1324 #if INCLUDE_CDS
1325 if (CDSConfig::is_using_archive())
1326 {
1327 PerfTraceTime vmtimer(ClassLoader::perf_shared_classload_time());
1328 InstanceKlass* ik = SystemDictionaryShared::find_builtin_class(class_name);
1329 if (ik != nullptr && ik->is_shared_boot_class() && !ik->shared_loading_failed()) {
1330 SharedClassLoadingMark slm(THREAD, ik);
1331 k = load_shared_class(ik, class_loader, Handle(), nullptr, pkg_entry, CHECK_NULL);
1332 }
1333 }
1334 #endif
1335
1336 if (k == nullptr) {
1337 // Use VM class loader
1338 PerfTraceTime vmtimer(ClassLoader::perf_sys_classload_time());
1339 k = ClassLoader::load_class(class_name, pkg_entry, search_only_bootloader_append, CHECK_NULL);
1340 }
1341
1342 // find_or_define_instance_class may return a different InstanceKlass
1343 if (k != nullptr) {
1344 CDS_ONLY(SharedClassLoadingMark slm(THREAD, k);)
1345 k = find_or_define_instance_class(class_name, class_loader, k, CHECK_NULL);
1346 }
1347 return k;
1348 } else {
1349 // Use user specified class loader to load class. Call loadClass operation on class_loader.
1350 ResourceMark rm(THREAD);
1351
1352 JavaThread* jt = THREAD;
1353
1354 PerfClassTraceTime vmtimer(ClassLoader::perf_app_classload_time(),
1355 ClassLoader::perf_app_classload_selftime(),
1356 ClassLoader::perf_app_classload_count(),
1357 jt->get_thread_stat()->perf_recursion_counts_addr(),
1358 jt->get_thread_stat()->perf_timers_addr(),
1359 PerfClassTraceTime::CLASS_LOAD);
1360
1361 // Translate to external class name format, i.e., convert '/' chars to '.'
1362 Handle string = java_lang_String::externalize_classname(class_name, CHECK_NULL);
1363
1364 JavaValue result(T_OBJECT);
1365
1366 InstanceKlass* spec_klass = vmClasses::ClassLoader_klass();
1367
1368 // Call public unsynchronized loadClass(String) directly for all class loaders.
1369 // For parallelCapable class loaders, JDK >=7, loadClass(String, boolean) will
1370 // acquire a class-name based lock rather than the class loader object lock.
1371 // JDK < 7 already acquire the class loader lock in loadClass(String, boolean).
1372 JavaCalls::call_virtual(&result,
1373 class_loader,
1374 spec_klass,
1375 vmSymbols::loadClass_name(),
1376 vmSymbols::string_class_signature(),
1377 string,
1378 CHECK_NULL);
1379
1380 assert(result.get_type() == T_OBJECT, "just checking");
1381 oop obj = result.get_oop();
1382
1383 // Primitive classes return null since forName() can not be
1384 // used to obtain any of the Class objects representing primitives or void
1385 if ((obj != nullptr) && !(java_lang_Class::is_primitive(obj))) {
1386 InstanceKlass* k = InstanceKlass::cast(java_lang_Class::as_Klass(obj));
1387 // For user defined Java class loaders, check that the name returned is
1388 // the same as that requested. This check is done for the bootstrap
1389 // loader when parsing the class file.
1390 if (class_name == k->name()) {
1391 return k;
1392 }
1393 }
1394 // Class is not found or has the wrong name, return null
1395 return nullptr;
1396 }
1397 }
1398
1399 InstanceKlass* SystemDictionary::load_instance_class(Symbol* name,
1400 Handle class_loader,
1401 TRAPS) {
1402
1403 InstanceKlass* loaded_class = load_instance_class_impl(name, class_loader, CHECK_NULL);
1404
1405 // If everything was OK (no exceptions, no null return value), and
1406 // class_loader is NOT the defining loader, do a little more bookkeeping.
1407 if (loaded_class != nullptr &&
1408 loaded_class->class_loader() != class_loader()) {
1409
1410 ClassLoaderData* loader_data = class_loader_data(class_loader);
1411 check_constraints(loaded_class, loader_data, false, CHECK_NULL);
1412
1413 // Record dependency for non-parent delegation.
1414 // This recording keeps the defining class loader of the klass (loaded_class) found
1415 // from being unloaded while the initiating class loader is loaded
1416 // even if the reference to the defining class loader is dropped
1417 // before references to the initiating class loader.
1418 loader_data->record_dependency(loaded_class);
1419
1420 update_dictionary(THREAD, loaded_class, loader_data);
1421
1422 if (JvmtiExport::should_post_class_load()) {
1423 JvmtiExport::post_class_load(THREAD, loaded_class);
1424 }
1425 }
1426 return loaded_class;
1427 }
1428
1429 static void post_class_define_event(InstanceKlass* k, const ClassLoaderData* def_cld) {
1430 EventClassDefine event;
1431 if (event.should_commit()) {
1432 event.set_definedClass(k);
1433 event.set_definingClassLoader(def_cld);
1434 event.commit();
1435 }
1436 }
1437
1438 void SystemDictionary::define_instance_class(InstanceKlass* k, Handle class_loader, TRAPS) {
1439
1440 ClassLoaderData* loader_data = k->class_loader_data();
1441 assert(loader_data->class_loader() == class_loader(), "they must be the same");
1442
1443 // Bootstrap and other parallel classloaders don't acquire a lock,
1444 // they use placeholder token.
1445 // If a parallelCapable class loader calls define_instance_class instead of
1446 // find_or_define_instance_class to get here, we have a timing
1447 // hole with systemDictionary updates and check_constraints
1448 if (!is_parallelCapable(class_loader)) {
1449 assert(ObjectSynchronizer::current_thread_holds_lock(THREAD,
1450 get_loader_lock_or_null(class_loader)),
1451 "define called without lock");
1452 }
1453
1454 // Check class-loading constraints. Throw exception if violation is detected.
1455 // Grabs and releases SystemDictionary_lock
1456 // The check_constraints/find_class call and update_dictionary sequence
1457 // must be "atomic" for a specific class/classloader pair so we never
1458 // define two different instanceKlasses for that class/classloader pair.
1459 // Existing classloaders will call define_instance_class with the
1460 // classloader lock held
1461 // Parallel classloaders will call find_or_define_instance_class
1462 // which will require a token to perform the define class
1463 check_constraints(k, loader_data, true, CHECK);
1464
1465 // Register class just loaded with class loader (placed in ArrayList)
1466 // Note we do this before updating the dictionary, as this can
1467 // fail with an OutOfMemoryError (if it does, we will *not* put this
1468 // class in the dictionary and will not update the class hierarchy).
1469 // JVMTI FollowReferences needs to find the classes this way.
1470 if (k->class_loader() != nullptr) {
1471 methodHandle m(THREAD, Universe::loader_addClass_method());
1472 JavaValue result(T_VOID);
1473 JavaCallArguments args(class_loader);
1474 args.push_oop(Handle(THREAD, k->java_mirror()));
1475 JavaCalls::call(&result, m, &args, CHECK);
1476 }
1477
1478 // Add to class hierarchy, and do possible deoptimizations.
1479 k->add_to_hierarchy(THREAD);
1480
1481 // Add to systemDictionary - so other classes can see it.
1482 // Grabs and releases SystemDictionary_lock
1483 update_dictionary(THREAD, k, loader_data);
1484
1485 // notify jvmti
1486 if (JvmtiExport::should_post_class_load()) {
1487 JvmtiExport::post_class_load(THREAD, k);
1488 }
1489 post_class_define_event(k, loader_data);
1490 }
1491
1492 // Support parallel classloading
1493 // All parallel class loaders, including bootstrap classloader
1494 // lock a placeholder entry for this class/class_loader pair
1495 // to allow parallel defines of different classes for this class loader
1496 // With AllowParallelDefine flag==true, in case they do not synchronize around
1497 // FindLoadedClass/DefineClass, calls, we check for parallel
1498 // loading for them, wait if a defineClass is in progress
1499 // and return the initial requestor's results
1500 // This flag does not apply to the bootstrap classloader.
1501 // With AllowParallelDefine flag==false, call through to define_instance_class
1502 // which will throw LinkageError: duplicate class definition.
1503 // False is the requested default.
1504 // For better performance, the class loaders should synchronize
1505 // findClass(), i.e. FindLoadedClass/DefineClassIfAbsent or they
1506 // potentially waste time reading and parsing the bytestream.
1507 // Note: VM callers should ensure consistency of k/class_name,class_loader
1508 // Be careful when modifying this code: once you have run
1509 // PlaceholderTable::find_and_add(PlaceholderTable::DEFINE_CLASS),
1510 // you need to find_and_remove it before returning.
1511 // So be careful to not exit with a CHECK_ macro between these calls.
1512 InstanceKlass* SystemDictionary::find_or_define_helper(Symbol* class_name, Handle class_loader,
1513 InstanceKlass* k, TRAPS) {
1514
1515 Symbol* name_h = k->name();
1516 ClassLoaderData* loader_data = class_loader_data(class_loader);
1517 Dictionary* dictionary = loader_data->dictionary();
1518
1519 // Hold SD lock around find_class and placeholder creation for DEFINE_CLASS
1520 {
1521 MutexLocker mu(THREAD, SystemDictionary_lock);
1522 // First check if class already defined
1523 if (is_parallelDefine(class_loader)) {
1524 InstanceKlass* check = dictionary->find_class(THREAD, name_h);
1525 if (check != nullptr) {
1526 return check;
1527 }
1528 }
1529
1530 // Acquire define token for this class/classloader
1531 PlaceholderEntry* probe = PlaceholderTable::find_and_add(name_h, loader_data,
1532 PlaceholderTable::DEFINE_CLASS, nullptr, THREAD);
1533 // Wait if another thread defining in parallel
1534 // All threads wait - even those that will throw duplicate class: otherwise
1535 // caller is surprised by LinkageError: duplicate, but findLoadedClass fails
1536 // if other thread has not finished updating dictionary
1537 while (probe->definer() != nullptr) {
1538 SystemDictionary_lock->wait();
1539 }
1540 // Only special cases allow parallel defines and can use other thread's results
1541 // Other cases fall through, and may run into duplicate defines
1542 // caught by finding an entry in the SystemDictionary
1543 if (is_parallelDefine(class_loader) && (probe->instance_klass() != nullptr)) {
1544 InstanceKlass* ik = probe->instance_klass();
1545 PlaceholderTable::find_and_remove(name_h, loader_data, PlaceholderTable::DEFINE_CLASS, THREAD);
1546 SystemDictionary_lock->notify_all();
1547 #ifdef ASSERT
1548 InstanceKlass* check = dictionary->find_class(THREAD, name_h);
1549 assert(check != nullptr, "definer missed recording success");
1550 #endif
1551 return ik;
1552 } else {
1553 // This thread will define the class (even if earlier thread tried and had an error)
1554 probe->set_definer(THREAD);
1555 }
1556 }
1557
1558 define_instance_class(k, class_loader, THREAD);
1559
1560 // definer must notify any waiting threads
1561 {
1562 MutexLocker mu(THREAD, SystemDictionary_lock);
1563 PlaceholderEntry* probe = PlaceholderTable::get_entry(name_h, loader_data);
1564 assert(probe != nullptr, "DEFINE_CLASS placeholder lost?");
1565 if (!HAS_PENDING_EXCEPTION) {
1566 probe->set_instance_klass(k);
1567 }
1568 probe->set_definer(nullptr);
1569 PlaceholderTable::find_and_remove(name_h, loader_data, PlaceholderTable::DEFINE_CLASS, THREAD);
1570 SystemDictionary_lock->notify_all();
1571 }
1572
1573 return HAS_PENDING_EXCEPTION ? nullptr : k;
1574 }
1575
1576 // If a class loader supports parallel classloading handle parallel define requests.
1577 // find_or_define_instance_class may return a different InstanceKlass
1578 InstanceKlass* SystemDictionary::find_or_define_instance_class(Symbol* class_name, Handle class_loader,
1579 InstanceKlass* k, TRAPS) {
1580 InstanceKlass* defined_k = find_or_define_helper(class_name, class_loader, k, THREAD);
1581 // Clean up original InstanceKlass if duplicate or error
1582 if (!HAS_PENDING_EXCEPTION && defined_k != k) {
1583 // If a parallel capable class loader already defined this class, register 'k' for cleanup.
1584 assert(defined_k != nullptr, "Should have a klass if there's no exception");
1585 k->class_loader_data()->add_to_deallocate_list(k);
1586 } else if (HAS_PENDING_EXCEPTION) {
1587 // Remove this InstanceKlass from the LoaderConstraintTable if added.
1588 LoaderConstraintTable::remove_failed_loaded_klass(k, class_loader_data(class_loader));
1589 assert(defined_k == nullptr, "Should not have a klass if there's an exception");
1590 k->class_loader_data()->add_to_deallocate_list(k);
1591 }
1592 return defined_k;
1593 }
1594
1595
1596 // ----------------------------------------------------------------------------
1597 // GC support
1598
1599 // Assumes classes in the SystemDictionary are only unloaded at a safepoint
1600 bool SystemDictionary::do_unloading(GCTimer* gc_timer) {
1601
1602 bool unloading_occurred;
1603 bool is_concurrent = !SafepointSynchronize::is_at_safepoint();
1604 {
1605 GCTraceTime(Debug, gc, phases) t("ClassLoaderData", gc_timer);
1606 assert_locked_or_safepoint(ClassLoaderDataGraph_lock); // caller locks.
1607 // First, mark for unload all ClassLoaderData referencing a dead class loader.
1608 unloading_occurred = ClassLoaderDataGraph::do_unloading();
1609 if (unloading_occurred) {
1610 ConditionalMutexLocker ml2(Module_lock, is_concurrent);
1611 JFR_ONLY(Jfr::on_unloading_classes();)
1612 MANAGEMENT_ONLY(FinalizerService::purge_unloaded();)
1613 ConditionalMutexLocker ml1(SystemDictionary_lock, is_concurrent);
1614 ClassLoaderDataGraph::clean_module_and_package_info();
1615 LoaderConstraintTable::purge_loader_constraints();
1616 ResolutionErrorTable::purge_resolution_errors();
1617 }
1618 }
1619
1620 GCTraceTime(Debug, gc, phases) t("Trigger cleanups", gc_timer);
1621
1622 if (unloading_occurred) {
1623 SymbolTable::trigger_cleanup();
1624
1625 if (java_lang_System::allow_security_manager()) {
1626 // Oops referenced by the protection domain cache table may get unreachable independently
1627 // of the class loader (eg. cached protection domain oops). So we need to
1628 // explicitly unlink them here.
1629 // All protection domain oops are linked to the caller class, so if nothing
1630 // unloads, this is not needed.
1631 ProtectionDomainCacheTable::trigger_cleanup();
1632 } else {
1633 assert(ProtectionDomainCacheTable::number_of_entries() == 0, "should be empty");
1634 }
1635
1636 ConditionalMutexLocker ml(ClassInitError_lock, is_concurrent);
1637 InstanceKlass::clean_initialization_error_table();
1638 }
1639
1640 return unloading_occurred;
1641 }
1642
1643 void SystemDictionary::methods_do(void f(Method*)) {
1644 // Walk methods in loaded classes
1645
1646 {
1647 MutexLocker ml(ClassLoaderDataGraph_lock);
1648 ClassLoaderDataGraph::methods_do(f);
1649 }
1650
1651 auto doit = [&] (InvokeMethodKey key, Method* method) {
1652 if (method != nullptr) {
1653 f(method);
1654 }
1655 };
1656
1657 {
1658 MutexLocker ml(InvokeMethodIntrinsicTable_lock);
1659 _invoke_method_intrinsic_table->iterate_all(doit);
1660 }
1661
1662 }
1663
1664 // ----------------------------------------------------------------------------
1665 // Initialization
1666
1667 void SystemDictionary::initialize(TRAPS) {
1668 _invoke_method_intrinsic_table = new (mtClass) InvokeMethodIntrinsicTable();
1669 _invoke_method_type_table = new (mtClass) InvokeMethodTypeTable();
1670 ResolutionErrorTable::initialize();
1671 LoaderConstraintTable::initialize();
1672 PlaceholderTable::initialize();
1673 ProtectionDomainCacheTable::initialize();
1674 #if INCLUDE_CDS
1675 SystemDictionaryShared::initialize();
1676 #endif
1677 // Resolve basic classes
1678 vmClasses::resolve_all(CHECK);
1679 // Resolve classes used by archived heap objects
1680 if (CDSConfig::is_using_archive()) {
1681 HeapShared::resolve_classes(THREAD);
1682 }
1683 }
1684
1685 // Constraints on class loaders. The details of the algorithm can be
1686 // found in the OOPSLA'98 paper "Dynamic Class Loading in the Java
1687 // Virtual Machine" by Sheng Liang and Gilad Bracha. The basic idea is
1688 // that the dictionary needs to maintain a set of constraints that
1689 // must be satisfied by all classes in the dictionary.
1690 // if defining is true, then LinkageError if already in dictionary
1691 // if initiating loader, then ok if InstanceKlass matches existing entry
1692
1693 void SystemDictionary::check_constraints(InstanceKlass* k,
1694 ClassLoaderData* loader_data,
1695 bool defining,
1696 TRAPS) {
1697 ResourceMark rm(THREAD);
1698 stringStream ss;
1699 bool throwException = false;
1700
1701 {
1702 Symbol* name = k->name();
1703
1704 MutexLocker mu(THREAD, SystemDictionary_lock);
1705
1706 InstanceKlass* check = loader_data->dictionary()->find_class(THREAD, name);
1707 if (check != nullptr) {
1708 // If different InstanceKlass - duplicate class definition,
1709 // else - ok, class loaded by a different thread in parallel.
1710 // We should only have found it if it was done loading and ok to use.
1711
1712 if ((defining == true) || (k != check)) {
1713 throwException = true;
1714 ss.print("loader %s", loader_data->loader_name_and_id());
1715 ss.print(" attempted duplicate %s definition for %s. (%s)",
1716 k->external_kind(), k->external_name(), k->class_in_module_of_loader(false, true));
1717 } else {
1718 return;
1719 }
1720 }
1721
1722 if (throwException == false) {
1723 if (LoaderConstraintTable::check_or_update(k, loader_data, name) == false) {
1724 throwException = true;
1725 ss.print("loader constraint violation: loader %s", loader_data->loader_name_and_id());
1726 ss.print(" wants to load %s %s.",
1727 k->external_kind(), k->external_name());
1728 Klass *existing_klass = LoaderConstraintTable::find_constrained_klass(name, loader_data);
1729 if (existing_klass != nullptr && existing_klass->class_loader_data() != loader_data) {
1730 ss.print(" A different %s with the same name was previously loaded by %s. (%s)",
1731 existing_klass->external_kind(),
1732 existing_klass->class_loader_data()->loader_name_and_id(),
1733 existing_klass->class_in_module_of_loader(false, true));
1734 } else {
1735 ss.print(" (%s)", k->class_in_module_of_loader(false, true));
1736 }
1737 }
1738 }
1739 }
1740
1741 // Throw error now if needed (cannot throw while holding
1742 // SystemDictionary_lock because of rank ordering)
1743 if (throwException == true) {
1744 THROW_MSG(vmSymbols::java_lang_LinkageError(), ss.as_string());
1745 }
1746 }
1747
1748 // Update class loader data dictionary - done after check_constraint and add_to_hierarchy
1749 // have been called.
1750 void SystemDictionary::update_dictionary(JavaThread* current,
1751 InstanceKlass* k,
1752 ClassLoaderData* loader_data) {
1753 MonitorLocker mu1(SystemDictionary_lock);
1754
1755 // Make a new dictionary entry.
1756 Symbol* name = k->name();
1757 Dictionary* dictionary = loader_data->dictionary();
1758 InstanceKlass* sd_check = dictionary->find_class(current, name);
1759 if (sd_check == nullptr) {
1760 dictionary->add_klass(current, name, k);
1761 }
1762 mu1.notify_all();
1763 }
1764
1765
1766 // Try to find a class name using the loader constraints. The
1767 // loader constraints might know about a class that isn't fully loaded
1768 // yet and these will be ignored.
1769 Klass* SystemDictionary::find_constrained_instance_or_array_klass(
1770 Thread* current, Symbol* class_name, Handle class_loader) {
1771
1772 // First see if it has been loaded directly.
1773 // Force the protection domain to be null. (This removes protection checks.)
1774 Handle no_protection_domain;
1775 Klass* klass = find_instance_or_array_klass(current, class_name, class_loader,
1776 no_protection_domain);
1777 if (klass != nullptr)
1778 return klass;
1779
1780 // Now look to see if it has been loaded elsewhere, and is subject to
1781 // a loader constraint that would require this loader to return the
1782 // klass that is already loaded.
1783 if (Signature::is_array(class_name)) {
1784 // For array classes, their Klass*s are not kept in the
1785 // constraint table. The element Klass*s are.
1786 SignatureStream ss(class_name, false);
1787 int ndims = ss.skip_array_prefix(); // skip all '['s
1788 BasicType t = ss.type();
1789 if (t != T_OBJECT) {
1790 klass = Universe::typeArrayKlass(t);
1791 } else {
1792 MutexLocker mu(current, SystemDictionary_lock);
1793 klass = LoaderConstraintTable::find_constrained_klass(ss.as_symbol(), class_loader_data(class_loader));
1794 }
1795 // If element class already loaded, allocate array klass
1796 if (klass != nullptr) {
1797 klass = klass->array_klass_or_null(ndims);
1798 }
1799 } else {
1800 MutexLocker mu(current, SystemDictionary_lock);
1801 // Non-array classes are easy: simply check the constraint table.
1802 klass = LoaderConstraintTable::find_constrained_klass(class_name, class_loader_data(class_loader));
1803 }
1804
1805 return klass;
1806 }
1807
1808 bool SystemDictionary::add_loader_constraint(Symbol* class_name,
1809 Klass* klass_being_linked,
1810 Handle class_loader1,
1811 Handle class_loader2) {
1812 ClassLoaderData* loader_data1 = class_loader_data(class_loader1);
1813 ClassLoaderData* loader_data2 = class_loader_data(class_loader2);
1814
1815 Symbol* constraint_name = nullptr;
1816
1817 if (!Signature::is_array(class_name)) {
1818 constraint_name = class_name;
1819 } else {
1820 // For array classes, their Klass*s are not kept in the
1821 // constraint table. The element classes are.
1822 SignatureStream ss(class_name, false);
1823 ss.skip_array_prefix(); // skip all '['s
1824 if (!ss.has_envelope()) {
1825 return true; // primitive types always pass
1826 }
1827 constraint_name = ss.as_symbol();
1828 // Increment refcount to keep constraint_name alive after
1829 // SignatureStream is destructed. It will be decremented below
1830 // before returning.
1831 constraint_name->increment_refcount();
1832 }
1833
1834 Dictionary* dictionary1 = loader_data1->dictionary();
1835 Dictionary* dictionary2 = loader_data2->dictionary();
1836
1837 JavaThread* current = JavaThread::current();
1838 {
1839 MutexLocker mu_s(SystemDictionary_lock);
1840 InstanceKlass* klass1 = dictionary1->find_class(current, constraint_name);
1841 InstanceKlass* klass2 = dictionary2->find_class(current, constraint_name);
1842 bool result = LoaderConstraintTable::add_entry(constraint_name, klass1, loader_data1,
1843 klass2, loader_data2);
1844 #if INCLUDE_CDS
1845 if (CDSConfig::is_dumping_archive() && klass_being_linked != nullptr &&
1846 !klass_being_linked->is_shared()) {
1847 SystemDictionaryShared::record_linking_constraint(constraint_name,
1848 InstanceKlass::cast(klass_being_linked),
1849 class_loader1, class_loader2);
1850 }
1851 #endif // INCLUDE_CDS
1852 if (Signature::is_array(class_name)) {
1853 constraint_name->decrement_refcount();
1854 }
1855 return result;
1856 }
1857 }
1858
1859 // Add entry to resolution error table to record the error when the first
1860 // attempt to resolve a reference to a class has failed.
1861 void SystemDictionary::add_resolution_error(const constantPoolHandle& pool, int which,
1862 Symbol* error, const char* message,
1863 Symbol* cause, const char* cause_msg) {
1864 {
1865 MutexLocker ml(Thread::current(), SystemDictionary_lock);
1866 ResolutionErrorEntry* entry = ResolutionErrorTable::find_entry(pool, which);
1867 if (entry == nullptr) {
1868 ResolutionErrorTable::add_entry(pool, which, error, message, cause, cause_msg);
1869 }
1870 }
1871 }
1872
1873 // Delete a resolution error for RedefineClasses for a constant pool is going away
1874 void SystemDictionary::delete_resolution_error(ConstantPool* pool) {
1875 ResolutionErrorTable::delete_entry(pool);
1876 }
1877
1878 // Lookup resolution error table. Returns error if found, otherwise null.
1879 Symbol* SystemDictionary::find_resolution_error(const constantPoolHandle& pool, int which,
1880 const char** message,
1881 Symbol** cause, const char** cause_msg) {
1882
1883 {
1884 MutexLocker ml(Thread::current(), SystemDictionary_lock);
1885 ResolutionErrorEntry* entry = ResolutionErrorTable::find_entry(pool, which);
1886 if (entry != nullptr) {
1887 *message = entry->message();
1888 *cause = entry->cause();
1889 *cause_msg = entry->cause_msg();
1890 return entry->error();
1891 } else {
1892 return nullptr;
1893 }
1894 }
1895 }
1896
1897 // Add an entry to resolution error table to record an error in resolving or
1898 // validating a nest host. This is used to construct informative error
1899 // messages when IllegalAccessError's occur. If an entry already exists it will
1900 // be updated with the nest host error message.
1901
1902 void SystemDictionary::add_nest_host_error(const constantPoolHandle& pool,
1903 int which,
1904 const char* message) {
1905 {
1906 MutexLocker ml(Thread::current(), SystemDictionary_lock);
1907 ResolutionErrorEntry* entry = ResolutionErrorTable::find_entry(pool, which);
1908 if (entry != nullptr && entry->nest_host_error() == nullptr) {
1909 // An existing entry means we had a true resolution failure (LinkageError) with our nest host, but we
1910 // still want to add the error message for the higher-level access checks to report. We should
1911 // only reach here under the same error condition, so we can ignore the potential race with setting
1912 // the message. If we see it is already set then we can ignore it.
1913 entry->set_nest_host_error(message);
1914 } else {
1915 ResolutionErrorTable::add_entry(pool, which, message);
1916 }
1917 }
1918 }
1919
1920 // Lookup any nest host error
1921 const char* SystemDictionary::find_nest_host_error(const constantPoolHandle& pool, int which) {
1922 {
1923 MutexLocker ml(Thread::current(), SystemDictionary_lock);
1924 ResolutionErrorEntry* entry = ResolutionErrorTable::find_entry(pool, which);
1925 if (entry != nullptr) {
1926 return entry->nest_host_error();
1927 } else {
1928 return nullptr;
1929 }
1930 }
1931 }
1932
1933 // Signature constraints ensure that callers and callees agree about
1934 // the meaning of type names in their signatures. This routine is the
1935 // intake for constraints. It collects them from several places:
1936 //
1937 // * LinkResolver::resolve_method (if check_access is true) requires
1938 // that the resolving class (the caller) and the defining class of
1939 // the resolved method (the callee) agree on each type in the
1940 // method's signature.
1941 //
1942 // * LinkResolver::resolve_interface_method performs exactly the same
1943 // checks.
1944 //
1945 // * LinkResolver::resolve_field requires that the constant pool
1946 // attempting to link to a field agree with the field's defining
1947 // class about the type of the field signature.
1948 //
1949 // * klassVtable::initialize_vtable requires that, when a class
1950 // overrides a vtable entry allocated by a superclass, that the
1951 // overriding method (i.e., the callee) agree with the superclass
1952 // on each type in the method's signature.
1953 //
1954 // * klassItable::initialize_itable requires that, when a class fills
1955 // in its itables, for each non-abstract method installed in an
1956 // itable, the method (i.e., the callee) agree with the interface
1957 // on each type in the method's signature.
1958 //
1959 // All those methods have a boolean (check_access, checkconstraints)
1960 // which turns off the checks. This is used from specialized contexts
1961 // such as bootstrapping, dumping, and debugging.
1962 //
1963 // No direct constraint is placed between the class and its
1964 // supertypes. Constraints are only placed along linked relations
1965 // between callers and callees. When a method overrides or implements
1966 // an abstract method in a supertype (superclass or interface), the
1967 // constraints are placed as if the supertype were the caller to the
1968 // overriding method. (This works well, since callers to the
1969 // supertype have already established agreement between themselves and
1970 // the supertype.) As a result of all this, a class can disagree with
1971 // its supertype about the meaning of a type name, as long as that
1972 // class neither calls a relevant method of the supertype, nor is
1973 // called (perhaps via an override) from the supertype.
1974 //
1975 //
1976 // SystemDictionary::check_signature_loaders(sig, klass_being_linked, l1, l2)
1977 //
1978 // Make sure all class components (including arrays) in the given
1979 // signature will be resolved to the same class in both loaders.
1980 // Returns the name of the type that failed a loader constraint check, or
1981 // null if no constraint failed. No exception except OOME is thrown.
1982 // Arrays are not added to the loader constraint table, their elements are.
1983 Symbol* SystemDictionary::check_signature_loaders(Symbol* signature,
1984 Klass* klass_being_linked,
1985 Handle loader1, Handle loader2,
1986 bool is_method) {
1987 // Nothing to do if loaders are the same.
1988 if (loader1() == loader2()) {
1989 return nullptr;
1990 }
1991
1992 for (SignatureStream ss(signature, is_method); !ss.is_done(); ss.next()) {
1993 if (ss.is_reference()) {
1994 Symbol* sig = ss.as_symbol();
1995 // Note: In the future, if template-like types can take
1996 // arguments, we will want to recognize them and dig out class
1997 // names hiding inside the argument lists.
1998 if (!add_loader_constraint(sig, klass_being_linked, loader1, loader2)) {
1999 return sig;
2000 }
2001 }
2002 }
2003 return nullptr;
2004 }
2005
2006 Method* SystemDictionary::find_method_handle_intrinsic(vmIntrinsicID iid,
2007 Symbol* signature,
2008 TRAPS) {
2009
2010 const int iid_as_int = vmIntrinsics::as_int(iid);
2011 assert(MethodHandles::is_signature_polymorphic(iid) &&
2012 MethodHandles::is_signature_polymorphic_intrinsic(iid) &&
2013 iid != vmIntrinsics::_invokeGeneric,
2014 "must be a known MH intrinsic iid=%d: %s", iid_as_int, vmIntrinsics::name_at(iid));
2015
2016 InvokeMethodKey key(signature, iid_as_int);
2017 Method** met = nullptr;
2018
2019 // We only want one entry in the table for this (signature/id, method) pair but the code
2020 // to create the intrinsic method needs to be outside the lock.
2021 // The first thread claims the entry by adding the key and the other threads wait, until the
2022 // Method has been added as the value.
2023 {
2024 MonitorLocker ml(THREAD, InvokeMethodIntrinsicTable_lock);
2025 while (true) {
2026 bool created;
2027 met = _invoke_method_intrinsic_table->put_if_absent(key, &created);
2028 assert(met != nullptr, "either created or found");
2029 if (*met != nullptr) {
2030 return *met;
2031 } else if (created) {
2032 // The current thread won the race and will try to create the full entry.
2033 break;
2034 } else {
2035 // Another thread beat us to it, so wait for them to complete
2036 // and return *met; or if they hit an error we get another try.
2037 ml.wait();
2038 // Note it is not safe to read *met here as that entry could have
2039 // been deleted, so we must loop and try put_if_absent again.
2040 }
2041 }
2042 }
2043
2044 methodHandle m = Method::make_method_handle_intrinsic(iid, signature, THREAD);
2045 bool throw_error = HAS_PENDING_EXCEPTION;
2046 if (!throw_error && (!Arguments::is_interpreter_only() || iid == vmIntrinsics::_linkToNative)) {
2047 // Generate a compiled form of the MH intrinsic
2048 // linkToNative doesn't have interpreter-specific implementation, so always has to go through compiled version.
2049 AdapterHandlerLibrary::create_native_wrapper(m);
2050 // Check if have the compiled code.
2051 throw_error = (!m->has_compiled_code());
2052 }
2053
2054 {
2055 MonitorLocker ml(THREAD, InvokeMethodIntrinsicTable_lock);
2056 if (throw_error) {
2057 // Remove the entry and let another thread try, or get the same exception.
2058 bool removed = _invoke_method_intrinsic_table->remove(key);
2059 assert(removed, "must be the owner");
2060 ml.notify_all();
2061 } else {
2062 signature->make_permanent(); // The signature is never unloaded.
2063 assert(Arguments::is_interpreter_only() || (m->has_compiled_code() &&
2064 m->code()->entry_point() == m->from_compiled_entry()),
2065 "MH intrinsic invariant");
2066 *met = m(); // insert the element
2067 ml.notify_all();
2068 return m();
2069 }
2070 }
2071
2072 // Throw OOM or the pending exception in the JavaThread
2073 if (throw_error && !HAS_PENDING_EXCEPTION) {
2074 THROW_MSG_NULL(vmSymbols::java_lang_OutOfMemoryError(),
2075 "Out of space in CodeCache for method handle intrinsic");
2076 }
2077 return nullptr;
2078 }
2079
2080 // Helper for unpacking the return value from linkMethod and linkCallSite.
2081 static Method* unpack_method_and_appendix(Handle mname,
2082 Klass* accessing_klass,
2083 objArrayHandle appendix_box,
2084 Handle* appendix_result,
2085 TRAPS) {
2086 if (mname.not_null()) {
2087 Method* m = java_lang_invoke_MemberName::vmtarget(mname());
2088 if (m != nullptr) {
2089 oop appendix = appendix_box->obj_at(0);
2090 LogTarget(Info, methodhandles) lt;
2091 if (lt.develop_is_enabled()) {
2092 ResourceMark rm(THREAD);
2093 LogStream ls(lt);
2094 ls.print("Linked method=" INTPTR_FORMAT ": ", p2i(m));
2095 m->print_on(&ls);
2096 if (appendix != nullptr) { ls.print("appendix = "); appendix->print_on(&ls); }
2097 ls.cr();
2098 }
2099
2100 (*appendix_result) = Handle(THREAD, appendix);
2101 // the target is stored in the cpCache and if a reference to this
2102 // MemberName is dropped we need a way to make sure the
2103 // class_loader containing this method is kept alive.
2104 methodHandle mh(THREAD, m); // record_dependency can safepoint.
2105 ClassLoaderData* this_key = accessing_klass->class_loader_data();
2106 this_key->record_dependency(m->method_holder());
2107 return mh();
2108 }
2109 }
2110 THROW_MSG_NULL(vmSymbols::java_lang_LinkageError(), "bad value from MethodHandleNatives");
2111 }
2112
2113 Method* SystemDictionary::find_method_handle_invoker(Klass* klass,
2114 Symbol* name,
2115 Symbol* signature,
2116 Klass* accessing_klass,
2117 Handle* appendix_result,
2118 TRAPS) {
2119 guarantee(THREAD->can_call_java(), "");
2120 Handle method_type =
2121 SystemDictionary::find_method_handle_type(signature, accessing_klass, CHECK_NULL);
2122
2123 int ref_kind = JVM_REF_invokeVirtual;
2124 oop name_oop = StringTable::intern(name, CHECK_NULL);
2125 Handle name_str (THREAD, name_oop);
2126 objArrayHandle appendix_box = oopFactory::new_objArray_handle(vmClasses::Object_klass(), 1, CHECK_NULL);
2127 assert(appendix_box->obj_at(0) == nullptr, "");
2128
2129 // This should not happen. JDK code should take care of that.
2130 if (accessing_klass == nullptr || method_type.is_null()) {
2131 THROW_MSG_NULL(vmSymbols::java_lang_InternalError(), "bad invokehandle");
2132 }
2133
2134 // call java.lang.invoke.MethodHandleNatives::linkMethod(... String, MethodType) -> MemberName
2135 JavaCallArguments args;
2136 args.push_oop(Handle(THREAD, accessing_klass->java_mirror()));
2137 args.push_int(ref_kind);
2138 args.push_oop(Handle(THREAD, klass->java_mirror()));
2139 args.push_oop(name_str);
2140 args.push_oop(method_type);
2141 args.push_oop(appendix_box);
2142 JavaValue result(T_OBJECT);
2143 JavaCalls::call_static(&result,
2144 vmClasses::MethodHandleNatives_klass(),
2145 vmSymbols::linkMethod_name(),
2146 vmSymbols::linkMethod_signature(),
2147 &args, CHECK_NULL);
2148 Handle mname(THREAD, result.get_oop());
2149 return unpack_method_and_appendix(mname, accessing_klass, appendix_box, appendix_result, THREAD);
2150 }
2151
2152 // Decide if we can globally cache a lookup of this class, to be returned to any client that asks.
2153 // We must ensure that all class loaders everywhere will reach this class, for any client.
2154 // This is a safe bet for public classes in java.lang, such as Object and String.
2155 // We also include public classes in java.lang.invoke, because they appear frequently in system-level method types.
2156 // Out of an abundance of caution, we do not include any other classes, not even for packages like java.util.
2157 static bool is_always_visible_class(oop mirror) {
2158 Klass* klass = java_lang_Class::as_Klass(mirror);
2159 if (klass->is_objArray_klass()) {
2160 klass = ObjArrayKlass::cast(klass)->bottom_klass(); // check element type
2161 }
2162 if (klass->is_typeArray_klass()) {
2163 return true; // primitive array
2164 }
2165 assert(klass->is_instance_klass(), "%s", klass->external_name());
2166 return klass->is_public() &&
2167 (InstanceKlass::cast(klass)->is_same_class_package(vmClasses::Object_klass()) || // java.lang
2168 InstanceKlass::cast(klass)->is_same_class_package(vmClasses::MethodHandle_klass())); // java.lang.invoke
2169 }
2170
2171 // Find or construct the Java mirror (java.lang.Class instance) for
2172 // the given field type signature, as interpreted relative to the
2173 // given class loader. Handles primitives, void, references, arrays,
2174 // and all other reflectable types, except method types.
2175 // N.B. Code in reflection should use this entry point.
2176 Handle SystemDictionary::find_java_mirror_for_type(Symbol* signature,
2177 Klass* accessing_klass,
2178 Handle class_loader,
2179 Handle protection_domain,
2180 SignatureStream::FailureMode failure_mode,
2181 TRAPS) {
2182 assert(accessing_klass == nullptr || (class_loader.is_null() && protection_domain.is_null()),
2183 "one or the other, or perhaps neither");
2184
2185 // What we have here must be a valid field descriptor,
2186 // and all valid field descriptors are supported.
2187 // Produce the same java.lang.Class that reflection reports.
2188 if (accessing_klass != nullptr) {
2189 class_loader = Handle(THREAD, accessing_klass->class_loader());
2190 protection_domain = Handle(THREAD, accessing_klass->protection_domain());
2191 }
2192 ResolvingSignatureStream ss(signature, class_loader, protection_domain, false);
2193 oop mirror_oop = ss.as_java_mirror(failure_mode, CHECK_NH);
2194 if (mirror_oop == nullptr) {
2195 return Handle(); // report failure this way
2196 }
2197 Handle mirror(THREAD, mirror_oop);
2198
2199 if (accessing_klass != nullptr) {
2200 // Check accessibility, emulating ConstantPool::verify_constant_pool_resolve.
2201 Klass* sel_klass = java_lang_Class::as_Klass(mirror());
2202 if (sel_klass != nullptr) {
2203 LinkResolver::check_klass_accessibility(accessing_klass, sel_klass, CHECK_NH);
2204 }
2205 }
2206 return mirror;
2207 }
2208
2209
2210 // Ask Java code to find or construct a java.lang.invoke.MethodType for the given
2211 // signature, as interpreted relative to the given class loader.
2212 // Because of class loader constraints, all method handle usage must be
2213 // consistent with this loader.
2214 Handle SystemDictionary::find_method_handle_type(Symbol* signature,
2215 Klass* accessing_klass,
2216 TRAPS) {
2217 Handle empty;
2218 OopHandle* o;
2219 {
2220 MutexLocker ml(THREAD, InvokeMethodTypeTable_lock);
2221 o = _invoke_method_type_table->get(signature);
2222 }
2223
2224 if (o != nullptr) {
2225 oop mt = o->resolve();
2226 assert(java_lang_invoke_MethodType::is_instance(mt), "");
2227 return Handle(THREAD, mt);
2228 } else if (!THREAD->can_call_java()) {
2229 warning("SystemDictionary::find_method_handle_type called from compiler thread"); // FIXME
2230 return Handle(); // do not attempt from within compiler, unless it was cached
2231 }
2232
2233 Handle class_loader, protection_domain;
2234 if (accessing_klass != nullptr) {
2235 class_loader = Handle(THREAD, accessing_klass->class_loader());
2236 protection_domain = Handle(THREAD, accessing_klass->protection_domain());
2237 }
2238 bool can_be_cached = true;
2239 int npts = ArgumentCount(signature).size();
2240 objArrayHandle pts = oopFactory::new_objArray_handle(vmClasses::Class_klass(), npts, CHECK_(empty));
2241 int arg = 0;
2242 Handle rt; // the return type from the signature
2243 ResourceMark rm(THREAD);
2244 for (SignatureStream ss(signature); !ss.is_done(); ss.next()) {
2245 oop mirror = nullptr;
2246 if (can_be_cached) {
2247 // Use neutral class loader to lookup candidate classes to be placed in the cache.
2248 mirror = ss.as_java_mirror(Handle(), Handle(),
2249 SignatureStream::ReturnNull, CHECK_(empty));
2250 if (mirror == nullptr || (ss.is_reference() && !is_always_visible_class(mirror))) {
2251 // Fall back to accessing_klass context.
2252 can_be_cached = false;
2253 }
2254 }
2255 if (!can_be_cached) {
2256 // Resolve, throwing a real error if it doesn't work.
2257 mirror = ss.as_java_mirror(class_loader, protection_domain,
2258 SignatureStream::NCDFError, CHECK_(empty));
2259 }
2260 assert(mirror != nullptr, "%s", ss.as_symbol()->as_C_string());
2261 if (ss.at_return_type())
2262 rt = Handle(THREAD, mirror);
2263 else
2264 pts->obj_at_put(arg++, mirror);
2265
2266 // Check accessibility.
2267 if (!java_lang_Class::is_primitive(mirror) && accessing_klass != nullptr) {
2268 Klass* sel_klass = java_lang_Class::as_Klass(mirror);
2269 mirror = nullptr; // safety
2270 // Emulate ConstantPool::verify_constant_pool_resolve.
2271 LinkResolver::check_klass_accessibility(accessing_klass, sel_klass, CHECK_(empty));
2272 }
2273 }
2274 assert(arg == npts, "");
2275
2276 // call java.lang.invoke.MethodHandleNatives::findMethodHandleType(Class rt, Class[] pts) -> MethodType
2277 JavaCallArguments args(Handle(THREAD, rt()));
2278 args.push_oop(pts);
2279 JavaValue result(T_OBJECT);
2280 JavaCalls::call_static(&result,
2281 vmClasses::MethodHandleNatives_klass(),
2282 vmSymbols::findMethodHandleType_name(),
2283 vmSymbols::findMethodHandleType_signature(),
2284 &args, CHECK_(empty));
2285 Handle method_type(THREAD, result.get_oop());
2286
2287 if (can_be_cached) {
2288 // We can cache this MethodType inside the JVM.
2289 MutexLocker ml(THREAD, InvokeMethodTypeTable_lock);
2290 bool created = false;
2291 assert(method_type != nullptr, "unexpected null");
2292 OopHandle* h = _invoke_method_type_table->get(signature);
2293 if (h == nullptr) {
2294 signature->make_permanent(); // The signature is never unloaded.
2295 OopHandle elem = OopHandle(Universe::vm_global(), method_type());
2296 bool created = _invoke_method_type_table->put(signature, elem);
2297 assert(created, "better be created");
2298 }
2299 }
2300 // report back to the caller with the MethodType
2301 return method_type;
2302 }
2303
2304 Handle SystemDictionary::find_field_handle_type(Symbol* signature,
2305 Klass* accessing_klass,
2306 TRAPS) {
2307 Handle empty;
2308 ResourceMark rm(THREAD);
2309 SignatureStream ss(signature, /*is_method=*/ false);
2310 if (!ss.is_done()) {
2311 Handle class_loader, protection_domain;
2312 if (accessing_klass != nullptr) {
2313 class_loader = Handle(THREAD, accessing_klass->class_loader());
2314 protection_domain = Handle(THREAD, accessing_klass->protection_domain());
2315 }
2316 oop mirror = ss.as_java_mirror(class_loader, protection_domain, SignatureStream::NCDFError, CHECK_(empty));
2317 ss.next();
2318 if (ss.is_done()) {
2319 return Handle(THREAD, mirror);
2320 }
2321 }
2322 return empty;
2323 }
2324
2325 // Ask Java code to find or construct a method handle constant.
2326 Handle SystemDictionary::link_method_handle_constant(Klass* caller,
2327 int ref_kind, //e.g., JVM_REF_invokeVirtual
2328 Klass* callee,
2329 Symbol* name,
2330 Symbol* signature,
2331 TRAPS) {
2332 Handle empty;
2333 if (caller == nullptr) {
2334 THROW_MSG_(vmSymbols::java_lang_InternalError(), "bad MH constant", empty);
2335 }
2336 Handle name_str = java_lang_String::create_from_symbol(name, CHECK_(empty));
2337 Handle signature_str = java_lang_String::create_from_symbol(signature, CHECK_(empty));
2338
2339 // Put symbolic info from the MH constant into freshly created MemberName and resolve it.
2340 Handle mname = vmClasses::MemberName_klass()->allocate_instance_handle(CHECK_(empty));
2341 java_lang_invoke_MemberName::set_clazz(mname(), callee->java_mirror());
2342 java_lang_invoke_MemberName::set_name (mname(), name_str());
2343 java_lang_invoke_MemberName::set_type (mname(), signature_str());
2344 java_lang_invoke_MemberName::set_flags(mname(), MethodHandles::ref_kind_to_flags(ref_kind));
2345
2346 if (ref_kind == JVM_REF_invokeVirtual &&
2347 MethodHandles::is_signature_polymorphic_public_name(callee, name)) {
2348 // Skip resolution for public signature polymorphic methods such as
2349 // j.l.i.MethodHandle.invoke()/invokeExact() and those on VarHandle
2350 // They require appendix argument which MemberName resolution doesn't handle.
2351 // There's special logic on JDK side to handle them
2352 // (see MethodHandles.linkMethodHandleConstant() and MethodHandles.findVirtualForMH()).
2353 } else {
2354 MethodHandles::resolve_MemberName(mname, caller, 0, false /*speculative_resolve*/, CHECK_(empty));
2355 }
2356
2357 // After method/field resolution succeeded, it's safe to resolve MH signature as well.
2358 Handle type = MethodHandles::resolve_MemberName_type(mname, caller, CHECK_(empty));
2359
2360 // call java.lang.invoke.MethodHandleNatives::linkMethodHandleConstant(Class caller, int refKind, Class callee, String name, Object type) -> MethodHandle
2361 JavaCallArguments args;
2362 args.push_oop(Handle(THREAD, caller->java_mirror())); // the referring class
2363 args.push_int(ref_kind);
2364 args.push_oop(Handle(THREAD, callee->java_mirror())); // the target class
2365 args.push_oop(name_str);
2366 args.push_oop(type);
2367 JavaValue result(T_OBJECT);
2368 JavaCalls::call_static(&result,
2369 vmClasses::MethodHandleNatives_klass(),
2370 vmSymbols::linkMethodHandleConstant_name(),
2371 vmSymbols::linkMethodHandleConstant_signature(),
2372 &args, CHECK_(empty));
2373 return Handle(THREAD, result.get_oop());
2374 }
2375
2376 // Ask Java to run a bootstrap method, in order to create a dynamic call site
2377 // while linking an invokedynamic op, or compute a constant for Dynamic_info CP entry
2378 // with linkage results being stored back into the bootstrap specifier.
2379 void SystemDictionary::invoke_bootstrap_method(BootstrapInfo& bootstrap_specifier, TRAPS) {
2380 // Resolve the bootstrap specifier, its name, type, and static arguments
2381 bootstrap_specifier.resolve_bsm(CHECK);
2382
2383 // This should not happen. JDK code should take care of that.
2384 if (bootstrap_specifier.caller() == nullptr || bootstrap_specifier.type_arg().is_null()) {
2385 THROW_MSG(vmSymbols::java_lang_InternalError(), "Invalid bootstrap method invocation with no caller or type argument");
2386 }
2387
2388 bool is_indy = bootstrap_specifier.is_method_call();
2389 objArrayHandle appendix_box;
2390 if (is_indy) {
2391 // Some method calls may require an appendix argument. Arrange to receive it.
2392 appendix_box = oopFactory::new_objArray_handle(vmClasses::Object_klass(), 1, CHECK);
2393 assert(appendix_box->obj_at(0) == nullptr, "");
2394 }
2395
2396 // call condy: java.lang.invoke.MethodHandleNatives::linkDynamicConstant(caller, bsm, type, info)
2397 // indy: java.lang.invoke.MethodHandleNatives::linkCallSite(caller, bsm, name, mtype, info, &appendix)
2398 JavaCallArguments args;
2399 args.push_oop(Handle(THREAD, bootstrap_specifier.caller_mirror()));
2400 args.push_oop(bootstrap_specifier.bsm());
2401 args.push_oop(bootstrap_specifier.name_arg());
2402 args.push_oop(bootstrap_specifier.type_arg());
2403 args.push_oop(bootstrap_specifier.arg_values());
2404 if (is_indy) {
2405 args.push_oop(appendix_box);
2406 }
2407 JavaValue result(T_OBJECT);
2408 JavaCalls::call_static(&result,
2409 vmClasses::MethodHandleNatives_klass(),
2410 is_indy ? vmSymbols::linkCallSite_name() : vmSymbols::linkDynamicConstant_name(),
2411 is_indy ? vmSymbols::linkCallSite_signature() : vmSymbols::linkDynamicConstant_signature(),
2412 &args, CHECK);
2413
2414 Handle value(THREAD, result.get_oop());
2415 if (is_indy) {
2416 Handle appendix;
2417 Method* method = unpack_method_and_appendix(value,
2418 bootstrap_specifier.caller(),
2419 appendix_box,
2420 &appendix, CHECK);
2421 methodHandle mh(THREAD, method);
2422 bootstrap_specifier.set_resolved_method(mh, appendix);
2423 } else {
2424 bootstrap_specifier.set_resolved_value(value);
2425 }
2426
2427 // sanity check
2428 assert(bootstrap_specifier.is_resolved() ||
2429 (bootstrap_specifier.is_method_call() &&
2430 bootstrap_specifier.resolved_method().not_null()), "bootstrap method call failed");
2431 }
2432
2433
2434 bool SystemDictionary::is_nonpublic_Object_method(Method* m) {
2435 assert(m != nullptr, "Unexpected nullptr Method*");
2436 return !m->is_public() && m->method_holder() == vmClasses::Object_klass();
2437 }
2438
2439 // ----------------------------------------------------------------------------
2440
2441 void SystemDictionary::print_on(outputStream *st) {
2442 CDS_ONLY(SystemDictionaryShared::print_on(st));
2443 GCMutexLocker mu(SystemDictionary_lock);
2444
2445 ClassLoaderDataGraph::print_dictionary(st);
2446
2447 // Placeholders
2448 PlaceholderTable::print_on(st);
2449 st->cr();
2450
2451 // loader constraints - print under SD_lock
2452 LoaderConstraintTable::print_on(st);
2453 st->cr();
2454
2455 ProtectionDomainCacheTable::print_on(st);
2456 st->cr();
2457 }
2458
2459 void SystemDictionary::print() { print_on(tty); }
2460
2461 void SystemDictionary::verify() {
2462
2463 GCMutexLocker mu(SystemDictionary_lock);
2464
2465 // Verify dictionary
2466 ClassLoaderDataGraph::verify_dictionary();
2467
2468 // Verify constraint table
2469 LoaderConstraintTable::verify();
2470
2471 // Verify protection domain table
2472 ProtectionDomainCacheTable::verify();
2473 }
2474
2475 void SystemDictionary::dump(outputStream *st, bool verbose) {
2476 assert_locked_or_safepoint(SystemDictionary_lock);
2477 if (verbose) {
2478 print_on(st);
2479 } else {
2480 CDS_ONLY(SystemDictionaryShared::print_table_statistics(st));
2481 ClassLoaderDataGraph::print_table_statistics(st);
2482 LoaderConstraintTable::print_table_statistics(st);
2483 ProtectionDomainCacheTable::print_table_statistics(st);
2484 }
2485 }
2486
2487 // Utility for dumping dictionaries.
2488 SystemDictionaryDCmd::SystemDictionaryDCmd(outputStream* output, bool heap) :
2489 DCmdWithParser(output, heap),
2490 _verbose("-verbose", "Dump the content of each dictionary entry for all class loaders",
2491 "BOOLEAN", false, "false") {
2492 _dcmdparser.add_dcmd_option(&_verbose);
2493 }
2494
2495 void SystemDictionaryDCmd::execute(DCmdSource source, TRAPS) {
2496 VM_DumpHashtable dumper(output(), VM_DumpHashtable::DumpSysDict,
2497 _verbose.value());
2498 VMThread::execute(&dumper);
2499 }