1 /*
2 * Copyright (c) 1997, 2024, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
24
25 #include "precompiled.hpp"
26 #include "cds/cdsConfig.hpp"
27 #include "cds/heapShared.hpp"
28 #include "classfile/classFileParser.hpp"
29 #include "classfile/classFileStream.hpp"
30 #include "classfile/classLoader.hpp"
31 #include "classfile/classLoaderData.inline.hpp"
32 #include "classfile/classLoaderDataGraph.inline.hpp"
33 #include "classfile/classLoaderExt.hpp"
34 #include "classfile/classLoadInfo.hpp"
35 #include "classfile/dictionary.hpp"
36 #include "classfile/javaClasses.inline.hpp"
37 #include "classfile/klassFactory.hpp"
38 #include "classfile/loaderConstraints.hpp"
39 #include "classfile/modules.hpp"
40 #include "classfile/packageEntry.hpp"
41 #include "classfile/placeholders.hpp"
42 #include "classfile/protectionDomainCache.hpp"
43 #include "classfile/resolutionErrors.hpp"
44 #include "classfile/stringTable.hpp"
45 #include "classfile/symbolTable.hpp"
46 #include "classfile/systemDictionary.hpp"
47 #include "classfile/vmClasses.hpp"
48 #include "classfile/vmSymbols.hpp"
49 #include "gc/shared/gcTraceTime.inline.hpp"
50 #include "interpreter/bootstrapInfo.hpp"
51 #include "jfr/jfrEvents.hpp"
52 #include "jvm.h"
53 #include "logging/log.hpp"
54 #include "logging/logStream.hpp"
55 #include "memory/metaspaceClosure.hpp"
56 #include "memory/oopFactory.hpp"
57 #include "memory/resourceArea.hpp"
58 #include "memory/universe.hpp"
59 #include "oops/access.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 "prims/jvmtiExport.hpp"
72 #include "prims/methodHandles.hpp"
73 #include "runtime/arguments.hpp"
74 #include "runtime/atomic.hpp"
75 #include "runtime/handles.inline.hpp"
76 #include "runtime/java.hpp"
77 #include "runtime/javaCalls.hpp"
78 #include "runtime/mutexLocker.hpp"
79 #include "runtime/sharedRuntime.hpp"
80 #include "runtime/signature.hpp"
81 #include "runtime/synchronizer.hpp"
82 #include "services/classLoadingService.hpp"
83 #include "services/diagnosticCommand.hpp"
84 #include "services/finalizerService.hpp"
85 #include "services/threadService.hpp"
86 #include "utilities/growableArray.hpp"
87 #include "utilities/macros.hpp"
88 #include "utilities/utf8.hpp"
89 #if INCLUDE_CDS
90 #include "classfile/systemDictionaryShared.hpp"
91 #endif
92 #if INCLUDE_JFR
93 #include "jfr/jfr.hpp"
94 #endif
95
96 class InvokeMethodKey : public StackObj {
97 private:
98 Symbol* _symbol;
99 intptr_t _iid;
100
101 public:
102 InvokeMethodKey(Symbol* symbol, intptr_t iid) :
103 _symbol(symbol),
104 _iid(iid) {}
105
106 static bool key_comparison(InvokeMethodKey const &k1, InvokeMethodKey const &k2){
107 return k1._symbol == k2._symbol && k1._iid == k2._iid;
108 }
109
110 static unsigned int compute_hash(const InvokeMethodKey &k) {
111 Symbol* sym = k._symbol;
112 intptr_t iid = k._iid;
113 unsigned int hash = (unsigned int) sym -> identity_hash();
114 return (unsigned int) (hash ^ iid);
115 }
116
117 };
118
119 using InvokeMethodIntrinsicTable = ResourceHashtable<InvokeMethodKey, Method*, 139, AnyObj::C_HEAP, mtClass,
120 InvokeMethodKey::compute_hash, InvokeMethodKey::key_comparison>;
121 static InvokeMethodIntrinsicTable* _invoke_method_intrinsic_table;
122 using InvokeMethodTypeTable = ResourceHashtable<SymbolHandle, OopHandle, 139, AnyObj::C_HEAP, mtClass, SymbolHandle::compute_hash>;
123 static InvokeMethodTypeTable* _invoke_method_type_table;
124
125 OopHandle SystemDictionary::_java_system_loader;
126 OopHandle SystemDictionary::_java_platform_loader;
127
128 // ----------------------------------------------------------------------------
129 // Java-level SystemLoader and PlatformLoader
130 oop SystemDictionary::java_system_loader() {
131 return _java_system_loader.resolve();
132 }
133
134 oop SystemDictionary::java_platform_loader() {
135 return _java_platform_loader.resolve();
136 }
137
138 void SystemDictionary::compute_java_loaders(TRAPS) {
139 if (_java_platform_loader.is_empty()) {
140 oop platform_loader = get_platform_class_loader_impl(CHECK);
141 _java_platform_loader = OopHandle(Universe::vm_global(), platform_loader);
142 } else {
143 // It must have been restored from the archived module graph
144 assert(CDSConfig::is_using_archive(), "must be");
145 assert(CDSConfig::is_using_full_module_graph(), "must be");
146 DEBUG_ONLY(
147 oop platform_loader = get_platform_class_loader_impl(CHECK);
148 assert(_java_platform_loader.resolve() == platform_loader, "must be");
149 )
150 }
151
152 if (_java_system_loader.is_empty()) {
153 oop system_loader = get_system_class_loader_impl(CHECK);
154 _java_system_loader = OopHandle(Universe::vm_global(), system_loader);
155 } else {
156 // It must have been restored from the archived module graph
157 assert(CDSConfig::is_using_archive(), "must be");
158 assert(CDSConfig::is_using_full_module_graph(), "must be");
159 DEBUG_ONLY(
160 oop system_loader = get_system_class_loader_impl(CHECK);
161 assert(_java_system_loader.resolve() == system_loader, "must be");
162 )
163 }
164
165 if (CDSConfig::is_dumping_final_static_archive()) {
166 AOTLinkedClassBulkLoader::load_non_javabase_classes(THREAD);
167 }
168 }
169
170 oop SystemDictionary::get_system_class_loader_impl(TRAPS) {
171 JavaValue result(T_OBJECT);
172 InstanceKlass* class_loader_klass = vmClasses::ClassLoader_klass();
173 JavaCalls::call_static(&result,
174 class_loader_klass,
175 vmSymbols::getSystemClassLoader_name(),
176 vmSymbols::void_classloader_signature(),
177 CHECK_NULL);
178 return result.get_oop();
179 }
180
181 oop SystemDictionary::get_platform_class_loader_impl(TRAPS) {
182 JavaValue result(T_OBJECT);
183 InstanceKlass* class_loader_klass = vmClasses::ClassLoader_klass();
184 JavaCalls::call_static(&result,
185 class_loader_klass,
186 vmSymbols::getPlatformClassLoader_name(),
187 vmSymbols::void_classloader_signature(),
188 CHECK_NULL);
189 return result.get_oop();
190 }
191
192 // Helper function
193 inline ClassLoaderData* class_loader_data(Handle class_loader) {
194 return ClassLoaderData::class_loader_data(class_loader());
195 }
196
197 ClassLoaderData* SystemDictionary::register_loader(Handle class_loader, bool create_mirror_cld) {
198 if (create_mirror_cld) {
199 // Add a new class loader data to the graph.
200 return ClassLoaderDataGraph::add(class_loader, true);
201 } else {
202 return (class_loader() == nullptr) ? ClassLoaderData::the_null_class_loader_data() :
203 ClassLoaderDataGraph::find_or_create(class_loader);
204 }
205 }
206
207 void SystemDictionary::set_system_loader(ClassLoaderData *cld) {
208 assert(_java_system_loader.is_empty(), "already set!");
209 _java_system_loader = cld->class_loader_handle();
210
211 }
212
213 void SystemDictionary::set_platform_loader(ClassLoaderData *cld) {
214 assert(_java_platform_loader.is_empty(), "already set!");
215 _java_platform_loader = cld->class_loader_handle();
216 }
217
218 // ----------------------------------------------------------------------------
219 // Parallel class loading check
220
221 static bool is_parallelCapable(Handle class_loader) {
222 if (class_loader.is_null()) return true;
223 return java_lang_ClassLoader::parallelCapable(class_loader());
224 }
225 // ----------------------------------------------------------------------------
226 // ParallelDefineClass flag does not apply to bootclass loader
227 static bool is_parallelDefine(Handle class_loader) {
228 if (class_loader.is_null()) return false;
229 if (AllowParallelDefineClass && java_lang_ClassLoader::parallelCapable(class_loader())) {
230 return true;
231 }
232 return false;
233 }
234
235 // Returns true if the passed class loader is the builtin application class loader
236 // or a custom system class loader. A customer system class loader can be
237 // specified via -Djava.system.class.loader.
238 bool SystemDictionary::is_system_class_loader(oop class_loader) {
239 if (class_loader == nullptr) {
240 return false;
241 }
242 return (class_loader->klass() == vmClasses::jdk_internal_loader_ClassLoaders_AppClassLoader_klass() ||
243 class_loader == _java_system_loader.peek());
244 }
245
246 // Returns true if the passed class loader is the platform class loader.
247 bool SystemDictionary::is_platform_class_loader(oop class_loader) {
248 if (class_loader == nullptr) {
249 return false;
250 }
251 return (class_loader->klass() == vmClasses::jdk_internal_loader_ClassLoaders_PlatformClassLoader_klass());
252 }
253
254 Handle SystemDictionary::get_loader_lock_or_null(Handle class_loader) {
255 // If class_loader is null or parallelCapable, the JVM doesn't acquire a lock while loading.
256 if (is_parallelCapable(class_loader)) {
257 return Handle();
258 } else {
259 return class_loader;
260 }
261 }
262
263 // ----------------------------------------------------------------------------
264 // Resolving of classes
265
266 Symbol* SystemDictionary::class_name_symbol(const char* name, Symbol* exception, TRAPS) {
267 if (name == nullptr) {
268 THROW_MSG_NULL(exception, "No class name given");
269 }
270 size_t name_len = strlen(name);
271 if (name_len > static_cast<size_t>(Symbol::max_length())) {
272 // It's impossible to create this class; the name cannot fit
273 // into the constant pool. If necessary report an abridged name
274 // in the exception message.
275 if (name_len > static_cast<size_t>(MaxStringPrintSize)) {
276 Exceptions::fthrow(THREAD_AND_LOCATION, exception,
277 "Class name exceeds maximum length of %d: %.*s ... (%zu characters omitted) ... %.*s",
278 Symbol::max_length(),
279 MaxStringPrintSize / 2,
280 name,
281 name_len - 2 * (MaxStringPrintSize / 2), // allows for odd value
282 MaxStringPrintSize / 2,
283 name + name_len - MaxStringPrintSize / 2);
284 }
285 else {
286 Exceptions::fthrow(THREAD_AND_LOCATION, exception,
287 "Class name exceeds maximum length of %d: %s",
288 Symbol::max_length(),
289 name);
290 }
291 return nullptr;
292 }
293 // Callers should ensure that the name is never an illegal UTF8 string.
294 assert(UTF8::is_legal_utf8((const unsigned char*)name, name_len, false),
295 "Class name is not a valid utf8 string.");
296
297 // Make a new symbol for the class name.
298 return SymbolTable::new_symbol(name);
299 }
300
301 #ifdef ASSERT
302 // Used to verify that class loading succeeded in adding k to the dictionary.
303 static void verify_dictionary_entry(Symbol* class_name, InstanceKlass* k) {
304 MutexLocker mu(SystemDictionary_lock);
305 ClassLoaderData* loader_data = k->class_loader_data();
306 Dictionary* dictionary = loader_data->dictionary();
307 assert(class_name == k->name(), "Must be the same");
308 InstanceKlass* kk = dictionary->find_class(JavaThread::current(), class_name);
309 assert(kk == k, "should be present in dictionary");
310 }
311 #endif
312
313 static void handle_resolution_exception(Symbol* class_name, bool throw_error, TRAPS) {
314 if (HAS_PENDING_EXCEPTION) {
315 // If we have a pending exception we forward it to the caller, unless throw_error is true,
316 // in which case we have to check whether the pending exception is a ClassNotFoundException,
317 // and convert it to a NoClassDefFoundError and chain the original ClassNotFoundException.
318 if (throw_error && PENDING_EXCEPTION->is_a(vmClasses::ClassNotFoundException_klass())) {
319 ResourceMark rm(THREAD);
320 Handle e(THREAD, PENDING_EXCEPTION);
321 CLEAR_PENDING_EXCEPTION;
322 THROW_MSG_CAUSE(vmSymbols::java_lang_NoClassDefFoundError(), class_name->as_C_string(), e);
323 } else {
324 return; // the caller will throw the incoming exception
325 }
326 }
327 // If the class is not found, ie, caller has checked that klass is null, throw the appropriate
328 // error or exception depending on the value of throw_error.
329 ResourceMark rm(THREAD);
330 if (throw_error) {
331 THROW_MSG(vmSymbols::java_lang_NoClassDefFoundError(), class_name->as_C_string());
332 } else {
333 THROW_MSG(vmSymbols::java_lang_ClassNotFoundException(), class_name->as_C_string());
334 }
335 }
336
337 // Forwards to resolve_or_null
338
339 Klass* SystemDictionary::resolve_or_fail(Symbol* class_name, Handle class_loader, Handle protection_domain,
340 bool throw_error, TRAPS) {
341 Klass* klass = resolve_or_null(class_name, class_loader, protection_domain, THREAD);
342 // Check for pending exception or null klass, and throw exception
343 if (HAS_PENDING_EXCEPTION || klass == nullptr) {
344 handle_resolution_exception(class_name, throw_error, CHECK_NULL);
345 }
346 return klass;
347 }
348
349 // Forwards to resolve_array_class_or_null or resolve_instance_class_or_null
350
351 Klass* SystemDictionary::resolve_or_null(Symbol* class_name, Handle class_loader, Handle protection_domain, TRAPS) {
352 if (Signature::is_array(class_name)) {
353 return resolve_array_class_or_null(class_name, class_loader, protection_domain, THREAD);
354 } else {
355 assert(class_name != nullptr && !Signature::is_array(class_name), "must be");
356 if (Signature::has_envelope(class_name)) {
357 ResourceMark rm(THREAD);
358 // Ignore wrapping L and ;.
359 TempNewSymbol name = SymbolTable::new_symbol(class_name->as_C_string() + 1,
360 class_name->utf8_length() - 2);
361 return resolve_instance_class_or_null(name, class_loader, protection_domain, THREAD);
362 } else {
363 return resolve_instance_class_or_null(class_name, class_loader, protection_domain, THREAD);
364 }
365 }
366 }
367
368 // Forwards to resolve_instance_class_or_null
369
370 Klass* SystemDictionary::resolve_array_class_or_null(Symbol* class_name,
371 Handle class_loader,
372 Handle protection_domain,
373 TRAPS) {
374 assert(Signature::is_array(class_name), "must be array");
375 ResourceMark rm(THREAD);
376 SignatureStream ss(class_name, false);
377 int ndims = ss.skip_array_prefix(); // skip all '['s
378 Klass* k = nullptr;
379 BasicType t = ss.type();
380 if (ss.has_envelope()) {
381 Symbol* obj_class = ss.as_symbol();
382 k = SystemDictionary::resolve_instance_class_or_null(obj_class,
383 class_loader,
384 protection_domain,
385 CHECK_NULL);
386 if (k != nullptr) {
387 k = k->array_klass(ndims, CHECK_NULL);
388 }
389 } else {
390 k = Universe::typeArrayKlass(t);
391 k = k->array_klass(ndims, CHECK_NULL);
392 }
393 return k;
394 }
395
396 static inline void log_circularity_error(Symbol* name, PlaceholderEntry* probe) {
397 LogTarget(Debug, class, load, placeholders) lt;
398 if (lt.is_enabled()) {
399 ResourceMark rm;
400 LogStream ls(lt);
401 ls.print("ClassCircularityError detected for placeholder entry %s", name->as_C_string());
402 probe->print_on(&ls);
403 ls.cr();
404 }
405 }
406
407 // Must be called for any superclass or superinterface resolution
408 // during class definition to allow class circularity checking
409 // superinterface callers:
410 // parse_interfaces - from defineClass
411 // superclass callers:
412 // ClassFileParser - from defineClass
413 // load_shared_class - while loading a class from shared archive
414 // resolve_instance_class_or_null:
415 // via: handle_parallel_super_load
416 // when resolving a class that has an existing placeholder with
417 // a saved superclass [i.e. a defineClass is currently in progress]
418 // If another thread is trying to resolve the class, it must do
419 // superclass checks on its own thread to catch class circularity and
420 // to avoid deadlock.
421 //
422 // resolve_with_circularity_detection adds a DETECT_CIRCULARITY placeholder to the placeholder table before calling
423 // resolve_instance_class_or_null. ClassCircularityError is detected when a DETECT_CIRCULARITY or LOAD_INSTANCE
424 // placeholder for the same thread, class, classloader is found.
425 // This can be seen with logging option: -Xlog:class+load+placeholders=debug.
426 //
427 InstanceKlass* SystemDictionary::resolve_with_circularity_detection(Symbol* class_name,
428 Symbol* next_name,
429 Handle class_loader,
430 Handle protection_domain,
431 bool is_superclass,
432 TRAPS) {
433
434 assert(next_name != nullptr, "null superclass for resolving");
435 assert(!Signature::is_array(next_name), "invalid superclass name");
436 #if INCLUDE_CDS
437 if (CDSConfig::is_dumping_static_archive()) {
438 // Special processing for handling UNREGISTERED shared classes.
439 InstanceKlass* k = SystemDictionaryShared::lookup_super_for_unregistered_class(class_name,
440 next_name, is_superclass);
441 if (k) {
442 return k;
443 }
444 }
445 #endif // INCLUDE_CDS
446
447 // If class_name is already loaded, just return the superclass or superinterface.
448 // Make sure there's a placeholder for the class_name before resolving.
449 // This is used as a claim that this thread is currently loading superclass/classloader
450 // and for ClassCircularity checks.
451
452 ClassLoaderData* loader_data = class_loader_data(class_loader);
453 Dictionary* dictionary = loader_data->dictionary();
454
455 // can't throw error holding a lock
456 bool throw_circularity_error = false;
457 {
458 MutexLocker mu(THREAD, SystemDictionary_lock);
459 InstanceKlass* klassk = dictionary->find_class(THREAD, class_name);
460 InstanceKlass* quicksuperk;
461 // To support parallel loading: if class is done loading, just return the superclass
462 // if the next_name matches class->super()->name() and if the class loaders match.
463 if (klassk != nullptr && is_superclass &&
464 ((quicksuperk = klassk->java_super()) != nullptr) &&
465 ((quicksuperk->name() == next_name) &&
466 (quicksuperk->class_loader() == class_loader()))) {
467 return quicksuperk;
468 } else {
469 // Must check ClassCircularity before checking if superclass is already loaded.
470 PlaceholderEntry* probe = PlaceholderTable::get_entry(class_name, loader_data);
471 if (probe && probe->check_seen_thread(THREAD, PlaceholderTable::DETECT_CIRCULARITY)) {
472 log_circularity_error(class_name, probe);
473 throw_circularity_error = true;
474 }
475 }
476
477 if (!throw_circularity_error) {
478 // Be careful not to exit resolve_with_circularity_detection without removing this placeholder.
479 PlaceholderEntry* newprobe = PlaceholderTable::find_and_add(class_name,
480 loader_data,
481 PlaceholderTable::DETECT_CIRCULARITY,
482 next_name, THREAD);
483 }
484 }
485
486 if (throw_circularity_error) {
487 ResourceMark rm(THREAD);
488 THROW_MSG_NULL(vmSymbols::java_lang_ClassCircularityError(), class_name->as_C_string());
489 }
490
491 // Resolve the superclass or superinterface, check results on return
492 InstanceKlass* superk =
493 SystemDictionary::resolve_instance_class_or_null(next_name,
494 class_loader,
495 protection_domain,
496 THREAD);
497
498 // Clean up placeholder entry.
499 {
500 MutexLocker mu(THREAD, SystemDictionary_lock);
501 PlaceholderTable::find_and_remove(class_name, loader_data, PlaceholderTable::DETECT_CIRCULARITY, THREAD);
502 SystemDictionary_lock->notify_all();
503 }
504
505 // Check for pending exception or null superk, and throw exception
506 if (HAS_PENDING_EXCEPTION || superk == nullptr) {
507 handle_resolution_exception(next_name, true, CHECK_NULL);
508 }
509
510 return superk;
511 }
512
513 // If the class in is in the placeholder table, class loading is in progress.
514 // For cases where the application changes threads to load classes, it
515 // is critical to ClassCircularity detection that we try loading
516 // the superclass on the new thread internally, so we do parallel
517 // superclass loading here. This avoids deadlock for ClassCircularity
518 // detection for parallelCapable class loaders that lock on a per-class lock.
519 static void handle_parallel_super_load(Symbol* name,
520 Symbol* superclassname,
521 Handle class_loader,
522 Handle protection_domain, TRAPS) {
523
524 // The result superk is not used; resolve_with_circularity_detection is called for circularity check only.
525 // This passes true to is_superclass even though it might not be the super class in order to perform the
526 // optimization anyway.
527 Klass* superk = SystemDictionary::resolve_with_circularity_detection(name,
528 superclassname,
529 class_loader,
530 protection_domain,
531 true,
532 CHECK);
533 }
534
535 // Bootstrap and non-parallel capable class loaders use the LOAD_INSTANCE placeholder to
536 // wait for parallel class loading and/or to check for circularity error for Xcomp when loading.
537 static bool needs_load_placeholder(Handle class_loader) {
538 return class_loader.is_null() || !is_parallelCapable(class_loader);
539 }
540
541 // Check for other threads loading this class either to throw CCE or wait in the case of the boot loader.
542 static InstanceKlass* handle_parallel_loading(JavaThread* current,
543 Symbol* name,
544 ClassLoaderData* loader_data,
545 bool must_wait_for_class_loading,
546 bool* throw_circularity_error) {
547 PlaceholderEntry* oldprobe = PlaceholderTable::get_entry(name, loader_data);
548 if (oldprobe != nullptr) {
549 // -Xcomp calls load_signature_classes which might result in loading
550 // a class that's already in the process of loading, so we detect CCE here also.
551 // Only need check_seen_thread once, not on each loop
552 if (oldprobe->check_seen_thread(current, PlaceholderTable::LOAD_INSTANCE)) {
553 log_circularity_error(name, oldprobe);
554 *throw_circularity_error = true;
555 return nullptr;
556 } else if (must_wait_for_class_loading) {
557 // Wait until the first thread has finished loading this class. Also wait until all the
558 // threads trying to load its superclass have removed their placeholders.
559 while (oldprobe != nullptr &&
560 (oldprobe->instance_load_in_progress() || oldprobe->circularity_detection_in_progress())) {
561
562 // LOAD_INSTANCE placeholders are used to implement parallel capable class loading
563 // for the bootclass loader.
564 SystemDictionary_lock->wait();
565
566 // Check if classloading completed while we were waiting
567 InstanceKlass* check = loader_data->dictionary()->find_class(current, name);
568 if (check != nullptr) {
569 // Klass is already loaded, so just return it
570 return check;
571 }
572 // check if other thread failed to load and cleaned up
573 oldprobe = PlaceholderTable::get_entry(name, loader_data);
574 }
575 }
576 }
577 return nullptr;
578 }
579
580 void SystemDictionary::post_class_load_event(EventClassLoad* event, const InstanceKlass* k, const ClassLoaderData* init_cld) {
581 assert(event != nullptr, "invariant");
582 assert(k != nullptr, "invariant");
583 event->set_loadedClass(k);
584 event->set_definingClassLoader(k->class_loader_data());
585 event->set_initiatingClassLoader(init_cld);
586 event->commit();
587 }
588
589 // SystemDictionary::resolve_instance_class_or_null is the main function for class name resolution.
590 // After checking if the InstanceKlass already exists, it checks for ClassCircularityError and
591 // whether the thread must wait for loading in parallel. It eventually calls load_instance_class,
592 // which will load the class via the bootstrap loader or call ClassLoader.loadClass().
593 // This can return null, an exception or an InstanceKlass.
594 InstanceKlass* SystemDictionary::resolve_instance_class_or_null(Symbol* name,
595 Handle class_loader,
596 Handle protection_domain,
597 TRAPS) {
598 // name must be in the form of "java/lang/Object" -- cannot be "Ljava/lang/Object;"
599 DEBUG_ONLY(ResourceMark rm(THREAD));
600 assert(name != nullptr && !Signature::is_array(name) &&
601 !Signature::has_envelope(name), "invalid class name: %s", name == nullptr ? "nullptr" : name->as_C_string());
602
603 EventClassLoad class_load_start_event;
604
605 HandleMark hm(THREAD);
606
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 ClassLoaderData* loader_data = ClassLoaderData::class_loader_data_or_null(class_loader());
773 if (loader_data == nullptr) {
774 // If the ClassLoaderData has not been setup,
775 // then the class loader has no entries in the dictionary.
776 return nullptr;
777 }
778
779 Dictionary* dictionary = loader_data->dictionary();
780 return dictionary->find(current, class_name, protection_domain);
781 }
782
783 // Look for a loaded instance or array klass by name. Do not do any loading.
784 // return null in case of error.
785 Klass* SystemDictionary::find_instance_or_array_klass(Thread* current,
786 Symbol* class_name,
787 Handle class_loader,
788 Handle protection_domain) {
789 Klass* k = nullptr;
790 assert(class_name != nullptr, "class name must be non nullptr");
791
792 if (Signature::is_array(class_name)) {
793 // The name refers to an array. Parse the name.
794 // dimension and object_key in FieldArrayInfo are assigned as a
795 // side-effect of this call
796 SignatureStream ss(class_name, false);
797 int ndims = ss.skip_array_prefix(); // skip all '['s
798 BasicType t = ss.type();
799 if (t != T_OBJECT) {
800 k = Universe::typeArrayKlass(t);
801 } else {
802 k = SystemDictionary::find_instance_klass(current, ss.as_symbol(), class_loader, protection_domain);
803 }
804 if (k != nullptr) {
805 k = k->array_klass_or_null(ndims);
806 }
807 } else {
808 k = find_instance_klass(current, class_name, class_loader, protection_domain);
809 }
810 return k;
811 }
812
813 // Note: this method is much like resolve_class_from_stream, but
814 // does not publish the classes in the SystemDictionary.
815 // Handles Lookup.defineClass hidden.
816 InstanceKlass* SystemDictionary::resolve_hidden_class_from_stream(
817 ClassFileStream* st,
818 Symbol* class_name,
819 Handle class_loader,
820 const ClassLoadInfo& cl_info,
821 TRAPS) {
822
823 EventClassLoad class_load_start_event;
824 ClassLoaderData* loader_data;
825
826 // - for hidden classes that are not strong: create a new CLD that has a class holder and
827 // whose loader is the Lookup class's loader.
828 // - for hidden class: add the class to the Lookup class's loader's CLD.
829 assert (cl_info.is_hidden(), "only used for hidden classes");
830 bool create_mirror_cld = !cl_info.is_strong_hidden();
831 loader_data = register_loader(class_loader, create_mirror_cld);
832
833 assert(st != nullptr, "invariant");
834
835 // Parse stream and create a klass.
836 InstanceKlass* k = KlassFactory::create_from_stream(st,
837 class_name,
838 loader_data,
839 cl_info,
840 CHECK_NULL);
841 assert(k != nullptr, "no klass created");
842
843 // Hidden classes that are not strong must update ClassLoaderData holder
844 // so that they can be unloaded when the mirror is no longer referenced.
845 if (!cl_info.is_strong_hidden()) {
846 k->class_loader_data()->initialize_holder(Handle(THREAD, k->java_mirror()));
847 }
848
849 // Add to class hierarchy, and do possible deoptimizations.
850 k->add_to_hierarchy(THREAD);
851 // But, do not add to dictionary.
852
853 k->link_class(CHECK_NULL);
854
855 // notify jvmti
856 if (JvmtiExport::should_post_class_load()) {
857 JvmtiExport::post_class_load(THREAD, k);
858 }
859 if (class_load_start_event.should_commit()) {
860 post_class_load_event(&class_load_start_event, k, loader_data);
861 }
862
863 return k;
864 }
865
866 // Add a klass to the system from a stream (called by jni_DefineClass and
867 // JVM_DefineClass).
868 // Note: class_name can be null. In that case we do not know the name of
869 // the class until we have parsed the stream.
870 // This function either returns an InstanceKlass or throws an exception. It does
871 // not return null without a pending exception.
872 InstanceKlass* SystemDictionary::resolve_class_from_stream(
873 ClassFileStream* st,
874 Symbol* class_name,
875 Handle class_loader,
876 const ClassLoadInfo& cl_info,
877 TRAPS) {
878
879 HandleMark hm(THREAD);
880
881 ClassLoaderData* loader_data = register_loader(class_loader);
882
883 // Classloaders that support parallelism, e.g. bootstrap classloader,
884 // do not acquire lock here
885 Handle lockObject = get_loader_lock_or_null(class_loader);
886 ObjectLocker ol(lockObject, THREAD);
887
888 // Parse the stream and create a klass.
889 // Note that we do this even though this klass might
890 // already be present in the SystemDictionary, otherwise we would not
891 // throw potential ClassFormatErrors.
892 InstanceKlass* k = nullptr;
893
894 #if INCLUDE_CDS
895 if (!CDSConfig::is_dumping_static_archive()) {
896 k = SystemDictionaryShared::lookup_from_stream(class_name,
897 class_loader,
898 cl_info.protection_domain(),
899 st,
900 CHECK_NULL);
901 }
902 #endif
903
904 if (k == nullptr) {
905 k = KlassFactory::create_from_stream(st, class_name, loader_data, cl_info, CHECK_NULL);
906 }
907
908 assert(k != nullptr, "no klass created");
909 Symbol* h_name = k->name();
910 assert(class_name == nullptr || class_name == h_name, "name mismatch");
911
912 // Add class just loaded
913 // If a class loader supports parallel classloading, handle parallel define requests.
914 // find_or_define_instance_class may return a different InstanceKlass,
915 // in which case the old k would be deallocated
916 if (is_parallelCapable(class_loader)) {
917 k = find_or_define_instance_class(h_name, class_loader, k, CHECK_NULL);
918 } else {
919 define_instance_class(k, class_loader, THREAD);
920
921 // If defining the class throws an exception register 'k' for cleanup.
922 if (HAS_PENDING_EXCEPTION) {
923 assert(k != nullptr, "Must have an instance klass here!");
924 loader_data->add_to_deallocate_list(k);
925 return nullptr;
926 }
927 }
928
929 // Make sure we have an entry in the SystemDictionary on success
930 DEBUG_ONLY(verify_dictionary_entry(h_name, k));
931
932 return k;
933 }
934
935 InstanceKlass* SystemDictionary::resolve_from_stream(ClassFileStream* st,
936 Symbol* class_name,
937 Handle class_loader,
938 const ClassLoadInfo& cl_info,
939 TRAPS) {
940 if (cl_info.is_hidden()) {
941 return resolve_hidden_class_from_stream(st, class_name, class_loader, cl_info, CHECK_NULL);
942 } else {
943 return resolve_class_from_stream(st, class_name, class_loader, cl_info, CHECK_NULL);
944 }
945 }
946
947
948 #if INCLUDE_CDS
949 // Check if a shared class can be loaded by the specific classloader.
950 bool SystemDictionary::is_shared_class_visible(Symbol* class_name,
951 InstanceKlass* ik,
952 PackageEntry* pkg_entry,
953 Handle class_loader) {
954 assert(!ModuleEntryTable::javabase_moduleEntry()->is_patched(),
955 "Cannot use sharing if java.base is patched");
956
957 // (1) Check if we are loading into the same loader as in dump time.
958
959 if (ik->is_shared_boot_class()) {
960 if (class_loader() != nullptr) {
961 return false;
962 }
963 } else if (ik->is_shared_platform_class()) {
964 if (class_loader() != java_platform_loader()) {
965 return false;
966 }
967 } else if (ik->is_shared_app_class()) {
968 if (class_loader() != java_system_loader()) {
969 return false;
970 }
971 } else {
972 // ik was loaded by a custom loader during dump time
973 if (class_loader_data(class_loader)->is_builtin_class_loader_data()) {
974 return false;
975 } else {
976 return true;
977 }
978 }
979
980 // (2) Check if we are loading into the same module from the same location as in dump time.
981
982 if (CDSConfig::is_using_optimized_module_handling()) {
983 // Class visibility has not changed between dump time and run time, so a class
984 // that was visible (and thus archived) during dump time is always visible during runtime.
985 assert(SystemDictionary::is_shared_class_visible_impl(class_name, ik, pkg_entry, class_loader),
986 "visibility cannot change between dump time and runtime");
987 return true;
988 }
989 return is_shared_class_visible_impl(class_name, ik, pkg_entry, class_loader);
990 }
991
992 bool SystemDictionary::is_shared_class_visible_impl(Symbol* class_name,
993 InstanceKlass* ik,
994 PackageEntry* pkg_entry,
995 Handle class_loader) {
996 int scp_index = ik->shared_classpath_index();
997 assert(!ik->is_shared_unregistered_class(), "this function should be called for built-in classes only");
998 assert(scp_index >= 0, "must be");
999 SharedClassPathEntry* scp_entry = FileMapInfo::shared_path(scp_index);
1000 if (!Universe::is_module_initialized()) {
1001 assert(scp_entry != nullptr, "must be");
1002 // At this point, no modules have been defined yet. KlassSubGraphInfo::check_allowed_klass()
1003 // has restricted the classes can be loaded at this step to be only:
1004 // [1] scp_entry->is_modules_image(): classes in java.base, or,
1005 // [2] HeapShared::is_a_test_class_in_unnamed_module(ik): classes in bootstrap/unnamed module
1006 assert(scp_entry->is_modules_image() || HeapShared::is_a_test_class_in_unnamed_module(ik),
1007 "only these classes can be loaded before the module system is initialized");
1008 assert(class_loader.is_null(), "sanity");
1009 return true;
1010 }
1011
1012 if (pkg_entry == nullptr) {
1013 // We might have looked up pkg_entry before the module system was initialized.
1014 // Need to reload it now.
1015 TempNewSymbol pkg_name = ClassLoader::package_from_class_name(class_name);
1016 if (pkg_name != nullptr) {
1017 pkg_entry = class_loader_data(class_loader)->packages()->lookup_only(pkg_name);
1018 }
1019 }
1020
1021 ModuleEntry* mod_entry = (pkg_entry == nullptr) ? nullptr : pkg_entry->module();
1022 bool should_be_in_named_module = (mod_entry != nullptr && mod_entry->is_named());
1023 bool was_archived_from_named_module = scp_entry->in_named_module();
1024 bool visible;
1025
1026 if (mod_entry != nullptr && mod_entry->location() == nullptr && mod_entry->is_named()) {
1027 // Archived module for dynamic proxies. It's always visible.
1028 assert(Modules::is_dynamic_proxy_module(mod_entry), "must be");
1029 visible = true;
1030 } else if (was_archived_from_named_module) {
1031 if (should_be_in_named_module) {
1032 // Is the module loaded from the same location as during dump time?
1033 visible = mod_entry->shared_path_index() == scp_index;
1034 if (visible) {
1035 assert(!mod_entry->is_patched(), "cannot load archived classes for patched module");
1036 }
1037 } else {
1038 // During dump time, this class was in a named module, but at run time, this class should be
1039 // in an unnamed module.
1040 visible = false;
1041 }
1042 } else {
1043 if (should_be_in_named_module) {
1044 // During dump time, this class was in an unnamed, but at run time, this class should be
1045 // in a named module.
1046 visible = false;
1047 } else {
1048 visible = true;
1049 }
1050 }
1051
1052 return visible;
1053 }
1054
1055 bool SystemDictionary::check_shared_class_super_type(InstanceKlass* klass, InstanceKlass* super_type,
1056 Handle class_loader, Handle protection_domain,
1057 bool is_superclass, TRAPS) {
1058 assert(super_type->is_shared(), "must be");
1059
1060 // Quick check if the super type has been already loaded.
1061 // + Don't do it for unregistered classes -- they can be unloaded so
1062 // super_type->class_loader_data() could be stale.
1063 // + Don't check if loader data is null, ie. the super_type isn't fully loaded.
1064 if (!super_type->is_shared_unregistered_class() && super_type->class_loader_data() != nullptr) {
1065 // Check if the superclass is loaded by the current class_loader
1066 Symbol* name = super_type->name();
1067 InstanceKlass* check = find_instance_klass(THREAD, name, class_loader, protection_domain);
1068 if (check == super_type) {
1069 return true;
1070 }
1071 }
1072
1073 Klass *found = resolve_with_circularity_detection(klass->name(), super_type->name(),
1074 class_loader, protection_domain, is_superclass, CHECK_false);
1075 if (found == super_type) {
1076 return true;
1077 } else {
1078 // The dynamically resolved super type is not the same as the one we used during dump time,
1079 // so we cannot use the class.
1080 return false;
1081 }
1082 }
1083
1084 bool SystemDictionary::check_shared_class_super_types(InstanceKlass* ik, Handle class_loader,
1085 Handle protection_domain, TRAPS) {
1086 // Check the superclass and interfaces. They must be the same
1087 // as in dump time, because the layout of <ik> depends on
1088 // the specific layout of ik->super() and ik->local_interfaces().
1089 //
1090 // If unexpected superclass or interfaces are found, we cannot
1091 // load <ik> from the shared archive.
1092
1093 if (ik->super() != nullptr) {
1094 bool check_super = check_shared_class_super_type(ik, InstanceKlass::cast(ik->super()),
1095 class_loader, protection_domain, true,
1096 CHECK_false);
1097 if (!check_super) {
1098 return false;
1099 }
1100 }
1101
1102 Array<InstanceKlass*>* interfaces = ik->local_interfaces();
1103 int num_interfaces = interfaces->length();
1104 for (int index = 0; index < num_interfaces; index++) {
1105 bool check_interface = check_shared_class_super_type(ik, interfaces->at(index), class_loader, protection_domain, false,
1106 CHECK_false);
1107 if (!check_interface) {
1108 return false;
1109 }
1110 }
1111
1112 return true;
1113 }
1114
1115 InstanceKlass* SystemDictionary::load_shared_lambda_proxy_class(InstanceKlass* ik,
1116 Handle class_loader,
1117 Handle protection_domain,
1118 PackageEntry* pkg_entry,
1119 TRAPS) {
1120 InstanceKlass* shared_nest_host = SystemDictionaryShared::get_shared_nest_host(ik);
1121 assert(shared_nest_host->is_shared(), "nest host must be in CDS archive");
1122 Symbol* cn = shared_nest_host->name();
1123 Klass *s = resolve_or_fail(cn, class_loader, protection_domain, true, CHECK_NULL);
1124 if (s != shared_nest_host) {
1125 // The dynamically resolved nest_host is not the same as the one we used during dump time,
1126 // so we cannot use ik.
1127 return nullptr;
1128 } else {
1129 assert(s->is_shared(), "must be");
1130 }
1131
1132 InstanceKlass* loaded_ik = load_shared_class(ik, class_loader, protection_domain, nullptr, pkg_entry, CHECK_NULL);
1133
1134 if (loaded_ik != nullptr) {
1135 assert(shared_nest_host->is_same_class_package(ik),
1136 "lambda proxy class and its nest host must be in the same package");
1137 // The lambda proxy class and its nest host have the same class loader and class loader data,
1138 // as verified in SystemDictionaryShared::add_lambda_proxy_class()
1139 assert(shared_nest_host->class_loader() == class_loader(), "mismatched class loader");
1140 assert(shared_nest_host->class_loader_data() == class_loader_data(class_loader), "mismatched class loader data");
1141 ik->set_nest_host(shared_nest_host);
1142 }
1143
1144 return loaded_ik;
1145 }
1146
1147 InstanceKlass* SystemDictionary::load_shared_class(InstanceKlass* ik,
1148 Handle class_loader,
1149 Handle protection_domain,
1150 const ClassFileStream *cfs,
1151 PackageEntry* pkg_entry,
1152 TRAPS) {
1153 assert(ik != nullptr, "sanity");
1154 assert(!ik->is_unshareable_info_restored(), "shared class can be restored only once");
1155 assert(Atomic::add(&ik->_shared_class_load_count, 1) == 1, "shared class loaded more than once");
1156 Symbol* class_name = ik->name();
1157
1158 if (!is_shared_class_visible(class_name, ik, pkg_entry, class_loader)) {
1159 ik->set_shared_loading_failed();
1160 return nullptr;
1161 }
1162
1163 bool check = check_shared_class_super_types(ik, class_loader, protection_domain, CHECK_NULL);
1164 if (!check) {
1165 ik->set_shared_loading_failed();
1166 return nullptr;
1167 }
1168
1169 InstanceKlass* new_ik = nullptr;
1170 // CFLH check is skipped for VM hidden classes (see KlassFactory::create_from_stream).
1171 // It will be skipped for shared VM hidden lambda proxy classes.
1172 if (!SystemDictionaryShared::is_hidden_lambda_proxy(ik)) {
1173 new_ik = KlassFactory::check_shared_class_file_load_hook(
1174 ik, class_name, class_loader, protection_domain, cfs, CHECK_NULL);
1175 }
1176 if (new_ik != nullptr) {
1177 // The class is changed by CFLH. Return the new class. The shared class is
1178 // not used.
1179 return new_ik;
1180 }
1181
1182 // Adjust methods to recover missing data. They need addresses for
1183 // interpreter entry points and their default native method address
1184 // must be reset.
1185
1186 // Shared classes are all currently loaded by either the bootstrap or
1187 // internal parallel class loaders, so this will never cause a deadlock
1188 // on a custom class loader lock.
1189 // Since this class is already locked with parallel capable class
1190 // loaders, including the bootstrap loader via the placeholder table,
1191 // this lock is currently a nop.
1192
1193 ClassLoaderData* loader_data = class_loader_data(class_loader);
1194 {
1195 HandleMark hm(THREAD);
1196 Handle lockObject = get_loader_lock_or_null(class_loader);
1197 ObjectLocker ol(lockObject, THREAD);
1198 // prohibited package check assumes all classes loaded from archive call
1199 // restore_unshareable_info which calls ik->set_package()
1200 ik->restore_unshareable_info(loader_data, protection_domain, pkg_entry, CHECK_NULL);
1201 }
1202
1203 load_shared_class_misc(ik, loader_data);
1204 return ik;
1205 }
1206
1207 void SystemDictionary::load_shared_class_misc(InstanceKlass* ik, ClassLoaderData* loader_data) {
1208 ik->print_class_load_logging(loader_data, nullptr, nullptr);
1209
1210 // For boot loader, ensure that GetSystemPackage knows that a class in this
1211 // package was loaded.
1212 if (loader_data->is_the_null_class_loader_data()) {
1213 s2 path_index = ik->shared_classpath_index();
1214 if (path_index >= 0) { // FIXME ... for lambda form classes
1215 ik->set_classpath_index(path_index);
1216
1217 if (CDSConfig::is_dumping_final_static_archive()) {
1218 if (path_index > ClassLoaderExt::max_used_path_index()) {
1219 ClassLoaderExt::set_max_used_path_index(path_index);
1220 }
1221 }
1222 }
1223 }
1224
1225 // notify a class loaded from shared object
1226 ClassLoadingService::notify_class_loaded(ik, true /* shared class */);
1227
1228 if (CDSConfig::is_dumping_final_static_archive()) {
1229 SystemDictionaryShared::init_dumptime_info(ik);
1230 if (SystemDictionary::is_platform_class_loader(loader_data->class_loader())) {
1231 ClassLoaderExt::set_has_platform_classes();
1232 } else if (SystemDictionary::is_system_class_loader(loader_data->class_loader())) {
1233 ClassLoaderExt::set_has_app_classes();
1234 }
1235 }
1236 }
1237
1238 #endif // INCLUDE_CDS
1239
1240 InstanceKlass* SystemDictionary::load_instance_class_impl(Symbol* class_name, Handle class_loader, TRAPS) {
1241
1242 if (class_loader.is_null()) {
1243 ResourceMark rm(THREAD);
1244 PackageEntry* pkg_entry = nullptr;
1245 bool search_only_bootloader_append = false;
1246
1247 // Find the package in the boot loader's package entry table.
1248 TempNewSymbol pkg_name = ClassLoader::package_from_class_name(class_name);
1249 if (pkg_name != nullptr) {
1250 pkg_entry = class_loader_data(class_loader)->packages()->lookup_only(pkg_name);
1251 }
1252
1253 // Prior to attempting to load the class, enforce the boot loader's
1254 // visibility boundaries.
1255 if (!Universe::is_module_initialized()) {
1256 // During bootstrapping, prior to module initialization, any
1257 // class attempting to be loaded must be checked against the
1258 // java.base packages in the boot loader's PackageEntryTable.
1259 // No class outside of java.base is allowed to be loaded during
1260 // this bootstrapping window.
1261 if (pkg_entry == nullptr || pkg_entry->in_unnamed_module()) {
1262 // Class is either in the unnamed package or in
1263 // a named package within the unnamed module. Either
1264 // case is outside of java.base, do not attempt to
1265 // load the class post java.base definition. If
1266 // java.base has not been defined, let the class load
1267 // and its package will be checked later by
1268 // ModuleEntryTable::verify_javabase_packages.
1269 if (ModuleEntryTable::javabase_defined()) {
1270 return nullptr;
1271 }
1272 } else {
1273 // Check that the class' package is defined within java.base.
1274 ModuleEntry* mod_entry = pkg_entry->module();
1275 Symbol* mod_entry_name = mod_entry->name();
1276 if (mod_entry_name->fast_compare(vmSymbols::java_base()) != 0) {
1277 return nullptr;
1278 }
1279 }
1280 } else {
1281 // After the module system has been initialized, check if the class'
1282 // package is in a module defined to the boot loader.
1283 if (pkg_name == nullptr || pkg_entry == nullptr || pkg_entry->in_unnamed_module()) {
1284 // Class is either in the unnamed package, in a named package
1285 // within a module not defined to the boot loader or in a
1286 // a named package within the unnamed module. In all cases,
1287 // limit visibility to search for the class only in the boot
1288 // loader's append path.
1289 if (!ClassLoader::has_bootclasspath_append()) {
1290 // If there is no bootclasspath append entry, no need to continue
1291 // searching.
1292 return nullptr;
1293 }
1294 search_only_bootloader_append = true;
1295 }
1296 }
1297
1298 // Prior to bootstrapping's module initialization, never load a class outside
1299 // of the boot loader's module path
1300 assert(Universe::is_module_initialized() ||
1301 !search_only_bootloader_append,
1302 "Attempt to load a class outside of boot loader's module path");
1303
1304 // Search for classes in the CDS archive.
1305 InstanceKlass* k = nullptr;
1306
1307 #if INCLUDE_CDS
1308 if (CDSConfig::is_using_archive())
1309 {
1310 PerfTraceElapsedTime vmtimer(ClassLoader::perf_shared_classload_time());
1311 InstanceKlass* ik = SystemDictionaryShared::find_builtin_class(class_name);
1312 if (ik != nullptr && ik->is_shared_boot_class() && !ik->shared_loading_failed()) {
1313 SharedClassLoadingMark slm(THREAD, ik);
1314 k = load_shared_class(ik, class_loader, Handle(), nullptr, pkg_entry, CHECK_NULL);
1315 }
1316 }
1317 #endif
1318
1319 if (k == nullptr) {
1320 // Use VM class loader
1321 PerfTraceElapsedTime vmtimer(ClassLoader::perf_sys_classload_time());
1322 k = ClassLoader::load_class(class_name, pkg_entry, search_only_bootloader_append, CHECK_NULL);
1323 }
1324
1325 // find_or_define_instance_class may return a different InstanceKlass
1326 if (k != nullptr) {
1327 CDS_ONLY(SharedClassLoadingMark slm(THREAD, k);)
1328 k = find_or_define_instance_class(class_name, class_loader, k, CHECK_NULL);
1329 }
1330 return k;
1331 } else {
1332 // Use user specified class loader to load class. Call loadClass operation on class_loader.
1333 ResourceMark rm(THREAD);
1334
1335 JavaThread* jt = THREAD;
1336
1337 PerfClassTraceTime vmtimer(ClassLoader::perf_app_classload_time(),
1338 ClassLoader::perf_app_classload_selftime(),
1339 ClassLoader::perf_app_classload_count(),
1340 jt->get_thread_stat()->perf_recursion_counts_addr(),
1341 jt->get_thread_stat()->perf_timers_addr(),
1342 PerfClassTraceTime::CLASS_LOAD);
1343
1344 // Translate to external class name format, i.e., convert '/' chars to '.'
1345 Handle string = java_lang_String::externalize_classname(class_name, CHECK_NULL);
1346
1347 JavaValue result(T_OBJECT);
1348
1349 InstanceKlass* spec_klass = vmClasses::ClassLoader_klass();
1350
1351 // Call public unsynchronized loadClass(String) directly for all class loaders.
1352 // For parallelCapable class loaders, JDK >=7, loadClass(String, boolean) will
1353 // acquire a class-name based lock rather than the class loader object lock.
1354 // JDK < 7 already acquire the class loader lock in loadClass(String, boolean).
1355 JavaCalls::call_virtual(&result,
1356 class_loader,
1357 spec_klass,
1358 vmSymbols::loadClass_name(),
1359 vmSymbols::string_class_signature(),
1360 string,
1361 CHECK_NULL);
1362
1363 assert(result.get_type() == T_OBJECT, "just checking");
1364 oop obj = result.get_oop();
1365
1366 // Primitive classes return null since forName() can not be
1367 // used to obtain any of the Class objects representing primitives or void
1368 if ((obj != nullptr) && !(java_lang_Class::is_primitive(obj))) {
1369 InstanceKlass* k = InstanceKlass::cast(java_lang_Class::as_Klass(obj));
1370 // For user defined Java class loaders, check that the name returned is
1371 // the same as that requested. This check is done for the bootstrap
1372 // loader when parsing the class file.
1373 if (class_name == k->name()) {
1374 return k;
1375 }
1376 }
1377 // Class is not found or has the wrong name, return null
1378 return nullptr;
1379 }
1380 }
1381
1382 InstanceKlass* SystemDictionary::load_instance_class(Symbol* name,
1383 Handle class_loader,
1384 TRAPS) {
1385
1386 InstanceKlass* loaded_class = load_instance_class_impl(name, class_loader, CHECK_NULL);
1387
1388 // If everything was OK (no exceptions, no null return value), and
1389 // class_loader is NOT the defining loader, do a little more bookkeeping.
1390 if (loaded_class != nullptr &&
1391 loaded_class->class_loader() != class_loader()) {
1392
1393 ClassLoaderData* loader_data = class_loader_data(class_loader);
1394 check_constraints(loaded_class, loader_data, false, CHECK_NULL);
1395
1396 // Record dependency for non-parent delegation.
1397 // This recording keeps the defining class loader of the klass (loaded_class) found
1398 // from being unloaded while the initiating class loader is loaded
1399 // even if the reference to the defining class loader is dropped
1400 // before references to the initiating class loader.
1401 loader_data->record_dependency(loaded_class);
1402
1403 update_dictionary(THREAD, loaded_class, loader_data);
1404
1405 if (JvmtiExport::should_post_class_load()) {
1406 JvmtiExport::post_class_load(THREAD, loaded_class);
1407 }
1408 }
1409 return loaded_class;
1410 }
1411
1412 static void post_class_define_event(InstanceKlass* k, const ClassLoaderData* def_cld) {
1413 EventClassDefine event;
1414 if (event.should_commit()) {
1415 event.set_definedClass(k);
1416 event.set_definingClassLoader(def_cld);
1417 event.commit();
1418 }
1419 }
1420
1421 void SystemDictionary::define_instance_class(InstanceKlass* k, Handle class_loader, TRAPS) {
1422
1423 ClassLoaderData* loader_data = k->class_loader_data();
1424 assert(loader_data->class_loader() == class_loader(), "they must be the same");
1425
1426 // Bootstrap and other parallel classloaders don't acquire a lock,
1427 // they use placeholder token.
1428 // If a parallelCapable class loader calls define_instance_class instead of
1429 // find_or_define_instance_class to get here, we have a timing
1430 // hole with systemDictionary updates and check_constraints
1431 if (!is_parallelCapable(class_loader)) {
1432 assert(ObjectSynchronizer::current_thread_holds_lock(THREAD,
1433 get_loader_lock_or_null(class_loader)),
1434 "define called without lock");
1435 }
1436
1437 // Check class-loading constraints. Throw exception if violation is detected.
1438 // Grabs and releases SystemDictionary_lock
1439 // The check_constraints/find_class call and update_dictionary sequence
1440 // must be "atomic" for a specific class/classloader pair so we never
1441 // define two different instanceKlasses for that class/classloader pair.
1442 // Existing classloaders will call define_instance_class with the
1443 // classloader lock held
1444 // Parallel classloaders will call find_or_define_instance_class
1445 // which will require a token to perform the define class
1446 check_constraints(k, loader_data, true, CHECK);
1447
1448 // Register class just loaded with class loader (placed in ArrayList)
1449 // Note we do this before updating the dictionary, as this can
1450 // fail with an OutOfMemoryError (if it does, we will *not* put this
1451 // class in the dictionary and will not update the class hierarchy).
1452 // JVMTI FollowReferences needs to find the classes this way.
1453 if (k->class_loader() != nullptr) {
1454 methodHandle m(THREAD, Universe::loader_addClass_method());
1455 JavaValue result(T_VOID);
1456 JavaCallArguments args(class_loader);
1457 args.push_oop(Handle(THREAD, k->java_mirror()));
1458 JavaCalls::call(&result, m, &args, CHECK);
1459 }
1460
1461 // Add to class hierarchy, and do possible deoptimizations.
1462 k->add_to_hierarchy(THREAD);
1463
1464 // Add to systemDictionary - so other classes can see it.
1465 // Grabs and releases SystemDictionary_lock
1466 update_dictionary(THREAD, k, loader_data);
1467
1468 // notify jvmti
1469 if (JvmtiExport::should_post_class_load()) {
1470 JvmtiExport::post_class_load(THREAD, k);
1471 }
1472 post_class_define_event(k, loader_data);
1473 }
1474
1475 // Support parallel classloading
1476 // All parallel class loaders, including bootstrap classloader
1477 // lock a placeholder entry for this class/class_loader pair
1478 // to allow parallel defines of different classes for this class loader
1479 // With AllowParallelDefine flag==true, in case they do not synchronize around
1480 // FindLoadedClass/DefineClass, calls, we check for parallel
1481 // loading for them, wait if a defineClass is in progress
1482 // and return the initial requestor's results
1483 // This flag does not apply to the bootstrap classloader.
1484 // With AllowParallelDefine flag==false, call through to define_instance_class
1485 // which will throw LinkageError: duplicate class definition.
1486 // False is the requested default.
1487 // For better performance, the class loaders should synchronize
1488 // findClass(), i.e. FindLoadedClass/DefineClassIfAbsent or they
1489 // potentially waste time reading and parsing the bytestream.
1490 // Note: VM callers should ensure consistency of k/class_name,class_loader
1491 // Be careful when modifying this code: once you have run
1492 // PlaceholderTable::find_and_add(PlaceholderTable::DEFINE_CLASS),
1493 // you need to find_and_remove it before returning.
1494 // So be careful to not exit with a CHECK_ macro between these calls.
1495 InstanceKlass* SystemDictionary::find_or_define_helper(Symbol* class_name, Handle class_loader,
1496 InstanceKlass* k, TRAPS) {
1497
1498 Symbol* name_h = k->name();
1499 ClassLoaderData* loader_data = class_loader_data(class_loader);
1500 Dictionary* dictionary = loader_data->dictionary();
1501
1502 // Hold SD lock around find_class and placeholder creation for DEFINE_CLASS
1503 {
1504 MutexLocker mu(THREAD, SystemDictionary_lock);
1505 // First check if class already defined
1506 if (is_parallelDefine(class_loader)) {
1507 InstanceKlass* check = dictionary->find_class(THREAD, name_h);
1508 if (check != nullptr) {
1509 return check;
1510 }
1511 }
1512
1513 // Acquire define token for this class/classloader
1514 PlaceholderEntry* probe = PlaceholderTable::find_and_add(name_h, loader_data,
1515 PlaceholderTable::DEFINE_CLASS, nullptr, THREAD);
1516 // Wait if another thread defining in parallel
1517 // All threads wait - even those that will throw duplicate class: otherwise
1518 // caller is surprised by LinkageError: duplicate, but findLoadedClass fails
1519 // if other thread has not finished updating dictionary
1520 while (probe->definer() != nullptr) {
1521 SystemDictionary_lock->wait();
1522 }
1523 // Only special cases allow parallel defines and can use other thread's results
1524 // Other cases fall through, and may run into duplicate defines
1525 // caught by finding an entry in the SystemDictionary
1526 if (is_parallelDefine(class_loader) && (probe->instance_klass() != nullptr)) {
1527 InstanceKlass* ik = probe->instance_klass();
1528 PlaceholderTable::find_and_remove(name_h, loader_data, PlaceholderTable::DEFINE_CLASS, THREAD);
1529 SystemDictionary_lock->notify_all();
1530 #ifdef ASSERT
1531 InstanceKlass* check = dictionary->find_class(THREAD, name_h);
1532 assert(check != nullptr, "definer missed recording success");
1533 #endif
1534 return ik;
1535 } else {
1536 // This thread will define the class (even if earlier thread tried and had an error)
1537 probe->set_definer(THREAD);
1538 }
1539 }
1540
1541 define_instance_class(k, class_loader, THREAD);
1542
1543 // definer must notify any waiting threads
1544 {
1545 MutexLocker mu(THREAD, SystemDictionary_lock);
1546 PlaceholderEntry* probe = PlaceholderTable::get_entry(name_h, loader_data);
1547 assert(probe != nullptr, "DEFINE_CLASS placeholder lost?");
1548 if (!HAS_PENDING_EXCEPTION) {
1549 probe->set_instance_klass(k);
1550 }
1551 probe->set_definer(nullptr);
1552 PlaceholderTable::find_and_remove(name_h, loader_data, PlaceholderTable::DEFINE_CLASS, THREAD);
1553 SystemDictionary_lock->notify_all();
1554 }
1555
1556 return HAS_PENDING_EXCEPTION ? nullptr : k;
1557 }
1558
1559 // If a class loader supports parallel classloading handle parallel define requests.
1560 // find_or_define_instance_class may return a different InstanceKlass
1561 InstanceKlass* SystemDictionary::find_or_define_instance_class(Symbol* class_name, Handle class_loader,
1562 InstanceKlass* k, TRAPS) {
1563 InstanceKlass* defined_k = find_or_define_helper(class_name, class_loader, k, THREAD);
1564 // Clean up original InstanceKlass if duplicate or error
1565 if (!HAS_PENDING_EXCEPTION && defined_k != k) {
1566 // If a parallel capable class loader already defined this class, register 'k' for cleanup.
1567 assert(defined_k != nullptr, "Should have a klass if there's no exception");
1568 k->class_loader_data()->add_to_deallocate_list(k);
1569 } else if (HAS_PENDING_EXCEPTION) {
1570 // Remove this InstanceKlass from the LoaderConstraintTable if added.
1571 LoaderConstraintTable::remove_failed_loaded_klass(k, class_loader_data(class_loader));
1572 assert(defined_k == nullptr, "Should not have a klass if there's an exception");
1573 k->class_loader_data()->add_to_deallocate_list(k);
1574 }
1575 return defined_k;
1576 }
1577
1578
1579 // ----------------------------------------------------------------------------
1580 // GC support
1581
1582 // Assumes classes in the SystemDictionary are only unloaded at a safepoint
1583 bool SystemDictionary::do_unloading(GCTimer* gc_timer) {
1584
1585 bool unloading_occurred;
1586 bool is_concurrent = !SafepointSynchronize::is_at_safepoint();
1587 {
1588 GCTraceTime(Debug, gc, phases) t("ClassLoaderData", gc_timer);
1589 assert_locked_or_safepoint(ClassLoaderDataGraph_lock); // caller locks.
1590 // First, mark for unload all ClassLoaderData referencing a dead class loader.
1591 unloading_occurred = ClassLoaderDataGraph::do_unloading();
1592 if (unloading_occurred) {
1593 ConditionalMutexLocker ml2(Module_lock, is_concurrent);
1594 JFR_ONLY(Jfr::on_unloading_classes();)
1595 MANAGEMENT_ONLY(FinalizerService::purge_unloaded();)
1596 ConditionalMutexLocker ml1(SystemDictionary_lock, is_concurrent);
1597 ClassLoaderDataGraph::clean_module_and_package_info();
1598 LoaderConstraintTable::purge_loader_constraints();
1599 ResolutionErrorTable::purge_resolution_errors();
1600 }
1601 }
1602
1603 GCTraceTime(Debug, gc, phases) t("Trigger cleanups", gc_timer);
1604
1605 if (unloading_occurred) {
1606 SymbolTable::trigger_cleanup();
1607
1608 if (java_lang_System::allow_security_manager()) {
1609 // Oops referenced by the protection domain cache table may get unreachable independently
1610 // of the class loader (eg. cached protection domain oops). So we need to
1611 // explicitly unlink them here.
1612 // All protection domain oops are linked to the caller class, so if nothing
1613 // unloads, this is not needed.
1614 ProtectionDomainCacheTable::trigger_cleanup();
1615 } else {
1616 assert(ProtectionDomainCacheTable::number_of_entries() == 0, "should be empty");
1617 }
1618
1619 ConditionalMutexLocker ml(ClassInitError_lock, is_concurrent);
1620 InstanceKlass::clean_initialization_error_table();
1621 }
1622
1623 return unloading_occurred;
1624 }
1625
1626 void SystemDictionary::methods_do(void f(Method*)) {
1627 // Walk methods in loaded classes
1628
1629 {
1630 MutexLocker ml(ClassLoaderDataGraph_lock);
1631 ClassLoaderDataGraph::methods_do(f);
1632 }
1633
1634 auto doit = [&] (InvokeMethodKey key, Method* method) {
1635 if (method != nullptr) {
1636 f(method);
1637 }
1638 };
1639
1640 {
1641 MutexLocker ml(InvokeMethodIntrinsicTable_lock);
1642 _invoke_method_intrinsic_table->iterate_all(doit);
1643 }
1644
1645 }
1646
1647 // ----------------------------------------------------------------------------
1648 // Initialization
1649
1650 void SystemDictionary::initialize(TRAPS) {
1651 _invoke_method_intrinsic_table = new (mtClass) InvokeMethodIntrinsicTable();
1652 _invoke_method_type_table = new (mtClass) InvokeMethodTypeTable();
1653 ResolutionErrorTable::initialize();
1654 LoaderConstraintTable::initialize();
1655 PlaceholderTable::initialize();
1656 ProtectionDomainCacheTable::initialize();
1657 #if INCLUDE_CDS
1658 SystemDictionaryShared::initialize();
1659 #endif
1660 // Resolve basic classes
1661 vmClasses::resolve_all(CHECK);
1662 // Resolve classes used by archived heap objects
1663 if (CDSConfig::is_using_archive()) {
1664 HeapShared::resolve_classes(THREAD);
1665 }
1666 }
1667
1668 // Constraints on class loaders. The details of the algorithm can be
1669 // found in the OOPSLA'98 paper "Dynamic Class Loading in the Java
1670 // Virtual Machine" by Sheng Liang and Gilad Bracha. The basic idea is
1671 // that the dictionary needs to maintain a set of constraints that
1672 // must be satisfied by all classes in the dictionary.
1673 // if defining is true, then LinkageError if already in dictionary
1674 // if initiating loader, then ok if InstanceKlass matches existing entry
1675
1676 void SystemDictionary::check_constraints(InstanceKlass* k,
1677 ClassLoaderData* loader_data,
1678 bool defining,
1679 TRAPS) {
1680 ResourceMark rm(THREAD);
1681 stringStream ss;
1682 bool throwException = false;
1683
1684 {
1685 Symbol* name = k->name();
1686
1687 MutexLocker mu(THREAD, SystemDictionary_lock);
1688
1689 InstanceKlass* check = loader_data->dictionary()->find_class(THREAD, name);
1690 if (check != nullptr) {
1691 // If different InstanceKlass - duplicate class definition,
1692 // else - ok, class loaded by a different thread in parallel.
1693 // We should only have found it if it was done loading and ok to use.
1694
1695 if ((defining == true) || (k != check)) {
1696 throwException = true;
1697 ss.print("loader %s", loader_data->loader_name_and_id());
1698 ss.print(" attempted duplicate %s definition for %s. (%s)",
1699 k->external_kind(), k->external_name(), k->class_in_module_of_loader(false, true));
1700 } else {
1701 return;
1702 }
1703 }
1704
1705 if (throwException == false) {
1706 if (LoaderConstraintTable::check_or_update(k, loader_data, name) == false) {
1707 throwException = true;
1708 ss.print("loader constraint violation: loader %s", loader_data->loader_name_and_id());
1709 ss.print(" wants to load %s %s.",
1710 k->external_kind(), k->external_name());
1711 Klass *existing_klass = LoaderConstraintTable::find_constrained_klass(name, loader_data);
1712 if (existing_klass != nullptr && existing_klass->class_loader_data() != loader_data) {
1713 ss.print(" A different %s with the same name was previously loaded by %s. (%s)",
1714 existing_klass->external_kind(),
1715 existing_klass->class_loader_data()->loader_name_and_id(),
1716 existing_klass->class_in_module_of_loader(false, true));
1717 } else {
1718 ss.print(" (%s)", k->class_in_module_of_loader(false, true));
1719 }
1720 }
1721 }
1722 }
1723
1724 // Throw error now if needed (cannot throw while holding
1725 // SystemDictionary_lock because of rank ordering)
1726 if (throwException == true) {
1727 THROW_MSG(vmSymbols::java_lang_LinkageError(), ss.as_string());
1728 }
1729 }
1730
1731 // Update class loader data dictionary - done after check_constraint and add_to_hierarchy
1732 // have been called.
1733 void SystemDictionary::update_dictionary(JavaThread* current,
1734 InstanceKlass* k,
1735 ClassLoaderData* loader_data) {
1736 MonitorLocker mu1(SystemDictionary_lock);
1737
1738 // Make a new dictionary entry.
1739 Symbol* name = k->name();
1740 Dictionary* dictionary = loader_data->dictionary();
1741 InstanceKlass* sd_check = dictionary->find_class(current, name);
1742 if (sd_check == nullptr) {
1743 dictionary->add_klass(current, name, k);
1744 }
1745 mu1.notify_all();
1746 }
1747
1748 #if INCLUDE_CDS
1749 // Indicate that loader_data has initiated the loading of class k, which
1750 // has already been defined by a parent loader.
1751 // This API should be used only by AOTLinkedClassBulkLoader
1752 void SystemDictionary::add_to_initiating_loader(JavaThread* current,
1753 InstanceKlass* k,
1754 ClassLoaderData* loader_data) {
1755 assert(CDSConfig::is_using_aot_linked_classes(), "must be");
1756 assert_locked_or_safepoint(SystemDictionary_lock);
1757 Symbol* name = k->name();
1758 Dictionary* dictionary = loader_data->dictionary();
1759 assert(k->is_loaded(), "must be");
1760 assert(k->class_loader_data() != loader_data, "only for classes defined by a parent loader");
1761 assert(dictionary->find_class(current, name) == nullptr, "sanity");
1762 dictionary->add_klass(current, name, k);
1763 }
1764 #endif
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 #if INCLUDE_CDS
2081 void SystemDictionary::get_all_method_handle_intrinsics(GrowableArray<Method*>* methods) {
2082 assert(SafepointSynchronize::is_at_safepoint(), "must be");
2083 auto do_method = [&] (InvokeMethodKey& key, Method*& m) {
2084 methods->append(m);
2085 };
2086 _invoke_method_intrinsic_table->iterate_all(do_method);
2087 }
2088
2089 void SystemDictionary::restore_archived_method_handle_intrinsics() {
2090 if (UseSharedSpaces) {
2091 EXCEPTION_MARK;
2092 restore_archived_method_handle_intrinsics_impl(THREAD);
2093 if (HAS_PENDING_EXCEPTION) {
2094 // This is probably caused by OOM -- other parts of the CDS archive have direct pointers to
2095 // the archived method handle intrinsics, so we can't really recover from this failure.
2096 vm_exit_during_initialization(err_msg("Failed to restore archived method handle intrinsics. Try to increase heap size."));
2097 }
2098 }
2099 }
2100
2101 void SystemDictionary::restore_archived_method_handle_intrinsics_impl(TRAPS) {
2102 Array<Method*>* list = MetaspaceShared::archived_method_handle_intrinsics();
2103 for (int i = 0; i < list->length(); i++) {
2104 methodHandle m(THREAD, list->at(i));
2105 Method::restore_archived_method_handle_intrinsic(m, CHECK);
2106 m->constants()->restore_unshareable_info(CHECK);
2107 if (!Arguments::is_interpreter_only() || m->intrinsic_id() == vmIntrinsics::_linkToNative) {
2108 AdapterHandlerLibrary::create_native_wrapper(m);
2109 if (!m->has_compiled_code()) {
2110 ResourceMark rm(THREAD);
2111 vm_exit_during_initialization(err_msg("Failed to initialize method %s", m->external_name()));
2112 }
2113 }
2114
2115 // There's no need to grab the InvokeMethodIntrinsicTable_lock, as we are still very early in
2116 // VM start-up -- in init_globals2() -- so we are still running a single Java thread. It's not
2117 // possible to have a contention.
2118 const int iid_as_int = vmIntrinsics::as_int(m->intrinsic_id());
2119 InvokeMethodKey key(m->signature(), iid_as_int);
2120 bool created = _invoke_method_intrinsic_table->put(key, m());
2121 assert(created, "unexpected contention");
2122 }
2123 }
2124 #endif // INCLUDE_CDS
2125
2126 // Helper for unpacking the return value from linkMethod and linkCallSite.
2127 static Method* unpack_method_and_appendix(Handle mname,
2128 Klass* accessing_klass,
2129 objArrayHandle appendix_box,
2130 Handle* appendix_result,
2131 TRAPS) {
2132 if (mname.not_null()) {
2133 Method* m = java_lang_invoke_MemberName::vmtarget(mname());
2134 if (m != nullptr) {
2135 oop appendix = appendix_box->obj_at(0);
2136 LogTarget(Info, methodhandles) lt;
2137 if (lt.develop_is_enabled()) {
2138 ResourceMark rm(THREAD);
2139 LogStream ls(lt);
2140 ls.print("Linked method=" INTPTR_FORMAT ": ", p2i(m));
2141 m->print_on(&ls);
2142 if (appendix != nullptr) { ls.print("appendix = "); appendix->print_on(&ls); }
2143 ls.cr();
2144 }
2145
2146 (*appendix_result) = Handle(THREAD, appendix);
2147 // the target is stored in the cpCache and if a reference to this
2148 // MemberName is dropped we need a way to make sure the
2149 // class_loader containing this method is kept alive.
2150 methodHandle mh(THREAD, m); // record_dependency can safepoint.
2151 ClassLoaderData* this_key = accessing_klass->class_loader_data();
2152 this_key->record_dependency(m->method_holder());
2153 return mh();
2154 }
2155 }
2156 THROW_MSG_NULL(vmSymbols::java_lang_LinkageError(), "bad value from MethodHandleNatives");
2157 }
2158
2159 Method* SystemDictionary::find_method_handle_invoker(Klass* klass,
2160 Symbol* name,
2161 Symbol* signature,
2162 Klass* accessing_klass,
2163 Handle* appendix_result,
2164 TRAPS) {
2165 guarantee(THREAD->can_call_java(), "");
2166 Handle method_type =
2167 SystemDictionary::find_method_handle_type(signature, accessing_klass, CHECK_NULL);
2168
2169 int ref_kind = JVM_REF_invokeVirtual;
2170 oop name_oop = StringTable::intern(name, CHECK_NULL);
2171 Handle name_str (THREAD, name_oop);
2172 objArrayHandle appendix_box = oopFactory::new_objArray_handle(vmClasses::Object_klass(), 1, CHECK_NULL);
2173 assert(appendix_box->obj_at(0) == nullptr, "");
2174
2175 // This should not happen. JDK code should take care of that.
2176 if (accessing_klass == nullptr || method_type.is_null()) {
2177 THROW_MSG_NULL(vmSymbols::java_lang_InternalError(), "bad invokehandle");
2178 }
2179
2180 // call java.lang.invoke.MethodHandleNatives::linkMethod(... String, MethodType) -> MemberName
2181 JavaCallArguments args;
2182 args.push_oop(Handle(THREAD, accessing_klass->java_mirror()));
2183 args.push_int(ref_kind);
2184 args.push_oop(Handle(THREAD, klass->java_mirror()));
2185 args.push_oop(name_str);
2186 args.push_oop(method_type);
2187 args.push_oop(appendix_box);
2188 JavaValue result(T_OBJECT);
2189 JavaCalls::call_static(&result,
2190 vmClasses::MethodHandleNatives_klass(),
2191 vmSymbols::linkMethod_name(),
2192 vmSymbols::linkMethod_signature(),
2193 &args, CHECK_NULL);
2194 Handle mname(THREAD, result.get_oop());
2195 return unpack_method_and_appendix(mname, accessing_klass, appendix_box, appendix_result, THREAD);
2196 }
2197
2198 // Decide if we can globally cache a lookup of this class, to be returned to any client that asks.
2199 // We must ensure that all class loaders everywhere will reach this class, for any client.
2200 // This is a safe bet for public classes in java.lang, such as Object and String.
2201 // We also include public classes in java.lang.invoke, because they appear frequently in system-level method types.
2202 // Out of an abundance of caution, we do not include any other classes, not even for packages like java.util.
2203 static bool is_always_visible_class(oop mirror) {
2204 Klass* klass = java_lang_Class::as_Klass(mirror);
2205 if (klass->is_objArray_klass()) {
2206 klass = ObjArrayKlass::cast(klass)->bottom_klass(); // check element type
2207 }
2208 if (klass->is_typeArray_klass()) {
2209 return true; // primitive array
2210 }
2211 assert(klass->is_instance_klass(), "%s", klass->external_name());
2212 return klass->is_public() &&
2213 (InstanceKlass::cast(klass)->is_same_class_package(vmClasses::Object_klass()) || // java.lang
2214 InstanceKlass::cast(klass)->is_same_class_package(vmClasses::MethodHandle_klass())); // java.lang.invoke
2215 }
2216
2217 // Find or construct the Java mirror (java.lang.Class instance) for
2218 // the given field type signature, as interpreted relative to the
2219 // given class loader. Handles primitives, void, references, arrays,
2220 // and all other reflectable types, except method types.
2221 // N.B. Code in reflection should use this entry point.
2222 Handle SystemDictionary::find_java_mirror_for_type(Symbol* signature,
2223 Klass* accessing_klass,
2224 Handle class_loader,
2225 Handle protection_domain,
2226 SignatureStream::FailureMode failure_mode,
2227 TRAPS) {
2228 assert(accessing_klass == nullptr || (class_loader.is_null() && protection_domain.is_null()),
2229 "one or the other, or perhaps neither");
2230
2231 // What we have here must be a valid field descriptor,
2232 // and all valid field descriptors are supported.
2233 // Produce the same java.lang.Class that reflection reports.
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 ResolvingSignatureStream ss(signature, class_loader, protection_domain, false);
2239 oop mirror_oop = ss.as_java_mirror(failure_mode, CHECK_NH);
2240 if (mirror_oop == nullptr) {
2241 return Handle(); // report failure this way
2242 }
2243 Handle mirror(THREAD, mirror_oop);
2244
2245 if (accessing_klass != nullptr) {
2246 // Check accessibility, emulating ConstantPool::verify_constant_pool_resolve.
2247 Klass* sel_klass = java_lang_Class::as_Klass(mirror());
2248 if (sel_klass != nullptr) {
2249 LinkResolver::check_klass_accessibility(accessing_klass, sel_klass, CHECK_NH);
2250 }
2251 }
2252 return mirror;
2253 }
2254
2255
2256 // Ask Java code to find or construct a java.lang.invoke.MethodType for the given
2257 // signature, as interpreted relative to the given class loader.
2258 // Because of class loader constraints, all method handle usage must be
2259 // consistent with this loader.
2260 Handle SystemDictionary::find_method_handle_type(Symbol* signature,
2261 Klass* accessing_klass,
2262 TRAPS) {
2263 Handle empty;
2264 OopHandle* o;
2265 {
2266 MutexLocker ml(THREAD, InvokeMethodTypeTable_lock);
2267 o = _invoke_method_type_table->get(signature);
2268 }
2269
2270 if (o != nullptr) {
2271 oop mt = o->resolve();
2272 assert(java_lang_invoke_MethodType::is_instance(mt), "");
2273 return Handle(THREAD, mt);
2274 } else if (!THREAD->can_call_java()) {
2275 warning("SystemDictionary::find_method_handle_type called from compiler thread"); // FIXME
2276 return Handle(); // do not attempt from within compiler, unless it was cached
2277 }
2278
2279 Handle class_loader, protection_domain;
2280 if (accessing_klass != nullptr) {
2281 class_loader = Handle(THREAD, accessing_klass->class_loader());
2282 protection_domain = Handle(THREAD, accessing_klass->protection_domain());
2283 }
2284 bool can_be_cached = true;
2285 int npts = ArgumentCount(signature).size();
2286 objArrayHandle pts = oopFactory::new_objArray_handle(vmClasses::Class_klass(), npts, CHECK_(empty));
2287 int arg = 0;
2288 Handle rt; // the return type from the signature
2289 ResourceMark rm(THREAD);
2290 for (SignatureStream ss(signature); !ss.is_done(); ss.next()) {
2291 oop mirror = nullptr;
2292 if (can_be_cached) {
2293 // Use neutral class loader to lookup candidate classes to be placed in the cache.
2294 mirror = ss.as_java_mirror(Handle(), Handle(),
2295 SignatureStream::ReturnNull, CHECK_(empty));
2296 if (mirror == nullptr || (ss.is_reference() && !is_always_visible_class(mirror))) {
2297 // Fall back to accessing_klass context.
2298 can_be_cached = false;
2299 }
2300 }
2301 if (!can_be_cached) {
2302 // Resolve, throwing a real error if it doesn't work.
2303 mirror = ss.as_java_mirror(class_loader, protection_domain,
2304 SignatureStream::NCDFError, CHECK_(empty));
2305 }
2306 assert(mirror != nullptr, "%s", ss.as_symbol()->as_C_string());
2307 if (ss.at_return_type())
2308 rt = Handle(THREAD, mirror);
2309 else
2310 pts->obj_at_put(arg++, mirror);
2311
2312 // Check accessibility.
2313 if (!java_lang_Class::is_primitive(mirror) && accessing_klass != nullptr) {
2314 Klass* sel_klass = java_lang_Class::as_Klass(mirror);
2315 mirror = nullptr; // safety
2316 // Emulate ConstantPool::verify_constant_pool_resolve.
2317 LinkResolver::check_klass_accessibility(accessing_klass, sel_klass, CHECK_(empty));
2318 }
2319 }
2320 assert(arg == npts, "");
2321
2322 // call java.lang.invoke.MethodHandleNatives::findMethodHandleType(Class rt, Class[] pts) -> MethodType
2323 JavaCallArguments args(Handle(THREAD, rt()));
2324 args.push_oop(pts);
2325 JavaValue result(T_OBJECT);
2326 JavaCalls::call_static(&result,
2327 vmClasses::MethodHandleNatives_klass(),
2328 vmSymbols::findMethodHandleType_name(),
2329 vmSymbols::findMethodHandleType_signature(),
2330 &args, CHECK_(empty));
2331 Handle method_type(THREAD, result.get_oop());
2332
2333 if (can_be_cached) {
2334 // We can cache this MethodType inside the JVM.
2335 MutexLocker ml(THREAD, InvokeMethodTypeTable_lock);
2336 bool created = false;
2337 assert(method_type != nullptr, "unexpected null");
2338 OopHandle* h = _invoke_method_type_table->get(signature);
2339 if (h == nullptr) {
2340 signature->make_permanent(); // The signature is never unloaded.
2341 OopHandle elem = OopHandle(Universe::vm_global(), method_type());
2342 bool created = _invoke_method_type_table->put(signature, elem);
2343 assert(created, "better be created");
2344 }
2345 }
2346 // report back to the caller with the MethodType
2347 return method_type;
2348 }
2349
2350 Handle SystemDictionary::find_field_handle_type(Symbol* signature,
2351 Klass* accessing_klass,
2352 TRAPS) {
2353 Handle empty;
2354 ResourceMark rm(THREAD);
2355 SignatureStream ss(signature, /*is_method=*/ false);
2356 if (!ss.is_done()) {
2357 Handle class_loader, protection_domain;
2358 if (accessing_klass != nullptr) {
2359 class_loader = Handle(THREAD, accessing_klass->class_loader());
2360 protection_domain = Handle(THREAD, accessing_klass->protection_domain());
2361 }
2362 oop mirror = ss.as_java_mirror(class_loader, protection_domain, SignatureStream::NCDFError, CHECK_(empty));
2363 ss.next();
2364 if (ss.is_done()) {
2365 return Handle(THREAD, mirror);
2366 }
2367 }
2368 return empty;
2369 }
2370
2371 // Ask Java code to find or construct a method handle constant.
2372 Handle SystemDictionary::link_method_handle_constant(Klass* caller,
2373 int ref_kind, //e.g., JVM_REF_invokeVirtual
2374 Klass* callee,
2375 Symbol* name,
2376 Symbol* signature,
2377 TRAPS) {
2378 Handle empty;
2379 if (caller == nullptr) {
2380 THROW_MSG_(vmSymbols::java_lang_InternalError(), "bad MH constant", empty);
2381 }
2382 Handle name_str = java_lang_String::create_from_symbol(name, CHECK_(empty));
2383 Handle signature_str = java_lang_String::create_from_symbol(signature, CHECK_(empty));
2384
2385 // Put symbolic info from the MH constant into freshly created MemberName and resolve it.
2386 Handle mname = vmClasses::MemberName_klass()->allocate_instance_handle(CHECK_(empty));
2387 java_lang_invoke_MemberName::set_clazz(mname(), callee->java_mirror());
2388 java_lang_invoke_MemberName::set_name (mname(), name_str());
2389 java_lang_invoke_MemberName::set_type (mname(), signature_str());
2390 java_lang_invoke_MemberName::set_flags(mname(), MethodHandles::ref_kind_to_flags(ref_kind));
2391
2392 if (ref_kind == JVM_REF_invokeVirtual &&
2393 MethodHandles::is_signature_polymorphic_public_name(callee, name)) {
2394 // Skip resolution for public signature polymorphic methods such as
2395 // j.l.i.MethodHandle.invoke()/invokeExact() and those on VarHandle
2396 // They require appendix argument which MemberName resolution doesn't handle.
2397 // There's special logic on JDK side to handle them
2398 // (see MethodHandles.linkMethodHandleConstant() and MethodHandles.findVirtualForMH()).
2399 } else {
2400 MethodHandles::resolve_MemberName(mname, caller, 0, false /*speculative_resolve*/, CHECK_(empty));
2401 }
2402
2403 // After method/field resolution succeeded, it's safe to resolve MH signature as well.
2404 Handle type = MethodHandles::resolve_MemberName_type(mname, caller, CHECK_(empty));
2405
2406 // call java.lang.invoke.MethodHandleNatives::linkMethodHandleConstant(Class caller, int refKind, Class callee, String name, Object type) -> MethodHandle
2407 JavaCallArguments args;
2408 args.push_oop(Handle(THREAD, caller->java_mirror())); // the referring class
2409 args.push_int(ref_kind);
2410 args.push_oop(Handle(THREAD, callee->java_mirror())); // the target class
2411 args.push_oop(name_str);
2412 args.push_oop(type);
2413 JavaValue result(T_OBJECT);
2414 JavaCalls::call_static(&result,
2415 vmClasses::MethodHandleNatives_klass(),
2416 vmSymbols::linkMethodHandleConstant_name(),
2417 vmSymbols::linkMethodHandleConstant_signature(),
2418 &args, CHECK_(empty));
2419 return Handle(THREAD, result.get_oop());
2420 }
2421
2422 // Ask Java to run a bootstrap method, in order to create a dynamic call site
2423 // while linking an invokedynamic op, or compute a constant for Dynamic_info CP entry
2424 // with linkage results being stored back into the bootstrap specifier.
2425 void SystemDictionary::invoke_bootstrap_method(BootstrapInfo& bootstrap_specifier, TRAPS) {
2426 // Resolve the bootstrap specifier, its name, type, and static arguments
2427 bootstrap_specifier.resolve_bsm(CHECK);
2428
2429 // This should not happen. JDK code should take care of that.
2430 if (bootstrap_specifier.caller() == nullptr || bootstrap_specifier.type_arg().is_null()) {
2431 THROW_MSG(vmSymbols::java_lang_InternalError(), "Invalid bootstrap method invocation with no caller or type argument");
2432 }
2433
2434 bool is_indy = bootstrap_specifier.is_method_call();
2435 objArrayHandle appendix_box;
2436 if (is_indy) {
2437 // Some method calls may require an appendix argument. Arrange to receive it.
2438 appendix_box = oopFactory::new_objArray_handle(vmClasses::Object_klass(), 1, CHECK);
2439 assert(appendix_box->obj_at(0) == nullptr, "");
2440 }
2441
2442 // call condy: java.lang.invoke.MethodHandleNatives::linkDynamicConstant(caller, bsm, type, info)
2443 // indy: java.lang.invoke.MethodHandleNatives::linkCallSite(caller, bsm, name, mtype, info, &appendix)
2444 JavaCallArguments args;
2445 args.push_oop(Handle(THREAD, bootstrap_specifier.caller_mirror()));
2446 args.push_oop(bootstrap_specifier.bsm());
2447 args.push_oop(bootstrap_specifier.name_arg());
2448 args.push_oop(bootstrap_specifier.type_arg());
2449 args.push_oop(bootstrap_specifier.arg_values());
2450 if (is_indy) {
2451 args.push_oop(appendix_box);
2452 }
2453 JavaValue result(T_OBJECT);
2454 JavaCalls::call_static(&result,
2455 vmClasses::MethodHandleNatives_klass(),
2456 is_indy ? vmSymbols::linkCallSite_name() : vmSymbols::linkDynamicConstant_name(),
2457 is_indy ? vmSymbols::linkCallSite_signature() : vmSymbols::linkDynamicConstant_signature(),
2458 &args, CHECK);
2459
2460 Handle value(THREAD, result.get_oop());
2461 if (is_indy) {
2462 Handle appendix;
2463 Method* method = unpack_method_and_appendix(value,
2464 bootstrap_specifier.caller(),
2465 appendix_box,
2466 &appendix, CHECK);
2467 methodHandle mh(THREAD, method);
2468 bootstrap_specifier.set_resolved_method(mh, appendix);
2469 } else {
2470 bootstrap_specifier.set_resolved_value(value);
2471 }
2472
2473 // sanity check
2474 assert(bootstrap_specifier.is_resolved() ||
2475 (bootstrap_specifier.is_method_call() &&
2476 bootstrap_specifier.resolved_method().not_null()), "bootstrap method call failed");
2477 }
2478
2479
2480 bool SystemDictionary::is_nonpublic_Object_method(Method* m) {
2481 assert(m != nullptr, "Unexpected nullptr Method*");
2482 return !m->is_public() && m->method_holder() == vmClasses::Object_klass();
2483 }
2484
2485 // ----------------------------------------------------------------------------
2486
2487 void SystemDictionary::print_on(outputStream *st) {
2488 CDS_ONLY(SystemDictionaryShared::print_on(st));
2489 GCMutexLocker mu(SystemDictionary_lock);
2490
2491 ClassLoaderDataGraph::print_dictionary(st);
2492
2493 // Placeholders
2494 PlaceholderTable::print_on(st);
2495 st->cr();
2496
2497 // loader constraints - print under SD_lock
2498 LoaderConstraintTable::print_on(st);
2499 st->cr();
2500
2501 ProtectionDomainCacheTable::print_on(st);
2502 st->cr();
2503 }
2504
2505 void SystemDictionary::print() { print_on(tty); }
2506
2507 void SystemDictionary::verify() {
2508
2509 GCMutexLocker mu(SystemDictionary_lock);
2510
2511 // Verify dictionary
2512 ClassLoaderDataGraph::verify_dictionary();
2513
2514 // Verify constraint table
2515 LoaderConstraintTable::verify();
2516
2517 // Verify protection domain table
2518 ProtectionDomainCacheTable::verify();
2519 }
2520
2521 void SystemDictionary::dump(outputStream *st, bool verbose) {
2522 assert_locked_or_safepoint(SystemDictionary_lock);
2523 if (verbose) {
2524 print_on(st);
2525 } else {
2526 CDS_ONLY(SystemDictionaryShared::print_table_statistics(st));
2527 ClassLoaderDataGraph::print_table_statistics(st);
2528 LoaderConstraintTable::print_table_statistics(st);
2529 ProtectionDomainCacheTable::print_table_statistics(st);
2530 }
2531 }
2532
2533 // Utility for dumping dictionaries.
2534 SystemDictionaryDCmd::SystemDictionaryDCmd(outputStream* output, bool heap) :
2535 DCmdWithParser(output, heap),
2536 _verbose("-verbose", "Dump the content of each dictionary entry for all class loaders",
2537 "BOOLEAN", false, "false") {
2538 _dcmdparser.add_dcmd_option(&_verbose);
2539 }
2540
2541 void SystemDictionaryDCmd::execute(DCmdSource source, TRAPS) {
2542 VM_DumpHashtable dumper(output(), VM_DumpHashtable::DumpSysDict,
2543 _verbose.value());
2544 VMThread::execute(&dumper);
2545 }