1 /*
2 * Copyright (c) 1997, 2015, 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 "classfile/classLoaderData.inline.hpp"
27 #include "classfile/dictionary.hpp"
28 #include "classfile/javaClasses.inline.hpp"
29 #include "classfile/loaderConstraints.hpp"
30 #include "classfile/placeholders.hpp"
31 #include "classfile/resolutionErrors.hpp"
32 #include "classfile/stringTable.hpp"
33 #include "classfile/systemDictionary.hpp"
34 #include "classfile/vmSymbols.hpp"
35 #include "code/codeCache.hpp"
36 #include "compiler/compileBroker.hpp"
37 #include "gc/shared/gcLocker.hpp"
38 #include "interpreter/bytecodeStream.hpp"
39 #include "interpreter/interpreter.hpp"
40 #include "memory/filemap.hpp"
41 #include "memory/oopFactory.hpp"
42 #include "oops/instanceKlass.hpp"
43 #include "oops/instanceRefKlass.hpp"
44 #include "oops/klass.inline.hpp"
45 #include "oops/methodData.hpp"
46 #include "oops/objArrayKlass.hpp"
47 #include "oops/objArrayOop.inline.hpp"
48 #include "oops/oop.inline.hpp"
49 #include "oops/typeArrayKlass.hpp"
50 #include "prims/jvmtiEnvBase.hpp"
51 #include "prims/methodHandles.hpp"
52 #include "runtime/arguments.hpp"
53 #include "runtime/biasedLocking.hpp"
54 #include "runtime/fieldType.hpp"
55 #include "runtime/handles.inline.hpp"
56 #include "runtime/java.hpp"
57 #include "runtime/javaCalls.hpp"
58 #include "runtime/mutexLocker.hpp"
59 #include "runtime/orderAccess.inline.hpp"
60 #include "runtime/signature.hpp"
61 #include "services/classLoadingService.hpp"
62 #include "services/threadService.hpp"
63 #include "utilities/macros.hpp"
64 #include "utilities/ticks.hpp"
65 #if INCLUDE_CDS
66 #include "classfile/sharedClassUtil.hpp"
67 #include "classfile/systemDictionaryShared.hpp"
68 #endif
69 #if INCLUDE_JVMCI
70 #include "jvmci/jvmciRuntime.hpp"
71 #endif
72 #if INCLUDE_TRACE
73 #include "trace/tracing.hpp"
74 #endif
75
76 Dictionary* SystemDictionary::_dictionary = NULL;
77 PlaceholderTable* SystemDictionary::_placeholders = NULL;
78 Dictionary* SystemDictionary::_shared_dictionary = NULL;
79 LoaderConstraintTable* SystemDictionary::_loader_constraints = NULL;
80 ResolutionErrorTable* SystemDictionary::_resolution_errors = NULL;
81 SymbolPropertyTable* SystemDictionary::_invoke_method_table = NULL;
82
83
84 int SystemDictionary::_number_of_modifications = 0;
85 int SystemDictionary::_sdgeneration = 0;
86 const int SystemDictionary::_primelist[_prime_array_size] = {1009,2017,4049,5051,10103,
87 20201,40423,99991};
88
89 oop SystemDictionary::_system_loader_lock_obj = NULL;
90
91 InstanceKlass* SystemDictionary::_well_known_klasses[SystemDictionary::WKID_LIMIT]
92 = { NULL /*, NULL...*/ };
93
94 InstanceKlass* SystemDictionary::_box_klasses[T_VOID+1] = { NULL /*, NULL...*/ };
95
96 oop SystemDictionary::_java_system_loader = NULL;
97
98 bool SystemDictionary::_has_loadClassInternal = false;
99 bool SystemDictionary::_has_checkPackageAccess = false;
100
101 // lazily initialized klass variables
102 InstanceKlass* volatile SystemDictionary::_abstract_ownable_synchronizer_klass = NULL;
103
104
105 // ----------------------------------------------------------------------------
106 // Java-level SystemLoader
107
108 oop SystemDictionary::java_system_loader() {
109 return _java_system_loader;
110 }
111
112 void SystemDictionary::compute_java_system_loader(TRAPS) {
113 KlassHandle system_klass(THREAD, WK_KLASS(ClassLoader_klass));
114 JavaValue result(T_OBJECT);
115 JavaCalls::call_static(&result,
116 KlassHandle(THREAD, WK_KLASS(ClassLoader_klass)),
117 vmSymbols::getSystemClassLoader_name(),
118 vmSymbols::void_classloader_signature(),
119 CHECK);
120
121 _java_system_loader = (oop)result.get_jobject();
122
123 CDS_ONLY(SystemDictionaryShared::initialize(CHECK);)
124 }
125
126
127 ClassLoaderData* SystemDictionary::register_loader(Handle class_loader, TRAPS) {
128 if (class_loader() == NULL) return ClassLoaderData::the_null_class_loader_data();
129 return ClassLoaderDataGraph::find_or_create(class_loader, THREAD);
130 }
131
132 // ----------------------------------------------------------------------------
133 // debugging
134
135 #ifdef ASSERT
136
137 // return true if class_name contains no '.' (internal format is '/')
138 bool SystemDictionary::is_internal_format(Symbol* class_name) {
139 if (class_name != NULL) {
140 ResourceMark rm;
141 char* name = class_name->as_C_string();
142 return strchr(name, '.') == NULL;
143 } else {
144 return true;
145 }
146 }
147
148 #endif
149
150 // ----------------------------------------------------------------------------
151 // Parallel class loading check
152
153 bool SystemDictionary::is_parallelCapable(Handle class_loader) {
154 if (UnsyncloadClass || class_loader.is_null()) return true;
155 if (AlwaysLockClassLoader) return false;
156 return java_lang_ClassLoader::parallelCapable(class_loader());
157 }
158 // ----------------------------------------------------------------------------
159 // ParallelDefineClass flag does not apply to bootclass loader
160 bool SystemDictionary::is_parallelDefine(Handle class_loader) {
161 if (class_loader.is_null()) return false;
162 if (AllowParallelDefineClass && java_lang_ClassLoader::parallelCapable(class_loader())) {
163 return true;
164 }
165 return false;
166 }
167
168 /**
169 * Returns true if the passed class loader is the extension class loader.
170 */
171 bool SystemDictionary::is_ext_class_loader(Handle class_loader) {
172 if (class_loader.is_null()) {
173 return false;
174 }
175 return (class_loader->klass()->name() == vmSymbols::sun_misc_Launcher_ExtClassLoader());
176 }
177
178 // ----------------------------------------------------------------------------
179 // Resolving of classes
180
181 // Forwards to resolve_or_null
182
183 Klass* SystemDictionary::resolve_or_fail(Symbol* class_name, Handle class_loader, Handle protection_domain, bool throw_error, TRAPS) {
184 Klass* klass = resolve_or_null(class_name, class_loader, protection_domain, THREAD);
185 if (HAS_PENDING_EXCEPTION || klass == NULL) {
186 KlassHandle k_h(THREAD, klass);
187 // can return a null klass
188 klass = handle_resolution_exception(class_name, throw_error, k_h, THREAD);
189 }
190 return klass;
191 }
192
193 Klass* SystemDictionary::handle_resolution_exception(Symbol* class_name,
194 bool throw_error,
195 KlassHandle klass_h, TRAPS) {
196 if (HAS_PENDING_EXCEPTION) {
197 // If we have a pending exception we forward it to the caller, unless throw_error is true,
198 // in which case we have to check whether the pending exception is a ClassNotFoundException,
199 // and if so convert it to a NoClassDefFoundError
200 // And chain the original ClassNotFoundException
201 if (throw_error && PENDING_EXCEPTION->is_a(SystemDictionary::ClassNotFoundException_klass())) {
202 ResourceMark rm(THREAD);
203 assert(klass_h() == NULL, "Should not have result with exception pending");
204 Handle e(THREAD, PENDING_EXCEPTION);
205 CLEAR_PENDING_EXCEPTION;
206 THROW_MSG_CAUSE_NULL(vmSymbols::java_lang_NoClassDefFoundError(), class_name->as_C_string(), e);
207 } else {
208 return NULL;
209 }
210 }
211 // Class not found, throw appropriate error or exception depending on value of throw_error
212 if (klass_h() == NULL) {
213 ResourceMark rm(THREAD);
214 if (throw_error) {
215 THROW_MSG_NULL(vmSymbols::java_lang_NoClassDefFoundError(), class_name->as_C_string());
216 } else {
217 THROW_MSG_NULL(vmSymbols::java_lang_ClassNotFoundException(), class_name->as_C_string());
218 }
219 }
220 return (Klass*)klass_h();
221 }
222
223
224 Klass* SystemDictionary::resolve_or_fail(Symbol* class_name,
225 bool throw_error, TRAPS)
226 {
227 return resolve_or_fail(class_name, Handle(), Handle(), throw_error, THREAD);
228 }
229
230
231 // Forwards to resolve_instance_class_or_null
232
233 Klass* SystemDictionary::resolve_or_null(Symbol* class_name, Handle class_loader, Handle protection_domain, TRAPS) {
234 assert(THREAD->can_call_java(),
235 "can not load classes with compiler thread: class=%s, classloader=%s",
236 class_name->as_C_string(),
237 class_loader.is_null() ? "null" : class_loader->klass()->name()->as_C_string());
238 if (FieldType::is_array(class_name)) {
239 return resolve_array_class_or_null(class_name, class_loader, protection_domain, THREAD);
240 } else if (FieldType::is_obj(class_name)) {
241 ResourceMark rm(THREAD);
242 // Ignore wrapping L and ;.
243 TempNewSymbol name = SymbolTable::new_symbol(class_name->as_C_string() + 1,
244 class_name->utf8_length() - 2, CHECK_NULL);
245 return resolve_instance_class_or_null(name, class_loader, protection_domain, THREAD);
246 } else {
247 return resolve_instance_class_or_null(class_name, class_loader, protection_domain, THREAD);
248 }
249 }
250
251 Klass* SystemDictionary::resolve_or_null(Symbol* class_name, TRAPS) {
252 return resolve_or_null(class_name, Handle(), Handle(), THREAD);
253 }
254
255 // Forwards to resolve_instance_class_or_null
256
257 Klass* SystemDictionary::resolve_array_class_or_null(Symbol* class_name,
258 Handle class_loader,
259 Handle protection_domain,
260 TRAPS) {
261 assert(FieldType::is_array(class_name), "must be array");
262 Klass* k = NULL;
263 FieldArrayInfo fd;
264 // dimension and object_key in FieldArrayInfo are assigned as a side-effect
265 // of this call
266 BasicType t = FieldType::get_array_info(class_name, fd, CHECK_NULL);
267 if (t == T_OBJECT) {
268 // naked oop "k" is OK here -- we assign back into it
269 k = SystemDictionary::resolve_instance_class_or_null(fd.object_key(),
270 class_loader,
271 protection_domain,
272 CHECK_NULL);
273 if (k != NULL) {
274 k = k->array_klass(fd.dimension(), CHECK_NULL);
275 }
276 } else {
277 k = Universe::typeArrayKlassObj(t);
278 k = TypeArrayKlass::cast(k)->array_klass(fd.dimension(), CHECK_NULL);
279 }
280 return k;
281 }
282
283
284 // Must be called for any super-class or super-interface resolution
285 // during class definition to allow class circularity checking
286 // super-interface callers:
287 // parse_interfaces - for defineClass & jvmtiRedefineClasses
288 // super-class callers:
289 // ClassFileParser - for defineClass & jvmtiRedefineClasses
290 // load_shared_class - while loading a class from shared archive
291 // resolve_instance_class_or_null:
292 // via: handle_parallel_super_load
293 // when resolving a class that has an existing placeholder with
294 // a saved superclass [i.e. a defineClass is currently in progress]
295 // if another thread is trying to resolve the class, it must do
296 // super-class checks on its own thread to catch class circularity
297 // This last call is critical in class circularity checking for cases
298 // where classloading is delegated to different threads and the
299 // classloader lock is released.
300 // Take the case: Base->Super->Base
301 // 1. If thread T1 tries to do a defineClass of class Base
302 // resolve_super_or_fail creates placeholder: T1, Base (super Super)
303 // 2. resolve_instance_class_or_null does not find SD or placeholder for Super
304 // so it tries to load Super
305 // 3. If we load the class internally, or user classloader uses same thread
306 // loadClassFromxxx or defineClass via parseClassFile Super ...
307 // 3.1 resolve_super_or_fail creates placeholder: T1, Super (super Base)
308 // 3.3 resolve_instance_class_or_null Base, finds placeholder for Base
309 // 3.4 calls resolve_super_or_fail Base
310 // 3.5 finds T1,Base -> throws class circularity
311 //OR 4. If T2 tries to resolve Super via defineClass Super ...
312 // 4.1 resolve_super_or_fail creates placeholder: T2, Super (super Base)
313 // 4.2 resolve_instance_class_or_null Base, finds placeholder for Base (super Super)
314 // 4.3 calls resolve_super_or_fail Super in parallel on own thread T2
315 // 4.4 finds T2, Super -> throws class circularity
316 // Must be called, even if superclass is null, since this is
317 // where the placeholder entry is created which claims this
318 // thread is loading this class/classloader.
319 Klass* SystemDictionary::resolve_super_or_fail(Symbol* child_name,
320 Symbol* class_name,
321 Handle class_loader,
322 Handle protection_domain,
323 bool is_superclass,
324 TRAPS) {
325 #if INCLUDE_CDS
326 if (DumpSharedSpaces) {
327 // Special processing for CDS dump time.
328 Klass* k = SystemDictionaryShared::dump_time_resolve_super_or_fail(child_name,
329 class_name, class_loader, protection_domain, is_superclass, CHECK_NULL);
330 if (k) {
331 return k;
332 }
333 }
334 #endif
335
336 // Double-check, if child class is already loaded, just return super-class,interface
337 // Don't add a placedholder if already loaded, i.e. already in system dictionary
338 // Make sure there's a placeholder for the *child* before resolving.
339 // Used as a claim that this thread is currently loading superclass/classloader
340 // Used here for ClassCircularity checks and also for heap verification
341 // (every InstanceKlass in the heap needs to be in the system dictionary
342 // or have a placeholder).
343 // Must check ClassCircularity before checking if super class is already loaded
344 //
345 // We might not already have a placeholder if this child_name was
346 // first seen via resolve_from_stream (jni_DefineClass or JVM_DefineClass);
347 // the name of the class might not be known until the stream is actually
348 // parsed.
349 // Bugs 4643874, 4715493
350 // compute_hash can have a safepoint
351
352 ClassLoaderData* loader_data = class_loader_data(class_loader);
353 unsigned int d_hash = dictionary()->compute_hash(child_name, loader_data);
354 int d_index = dictionary()->hash_to_index(d_hash);
355 unsigned int p_hash = placeholders()->compute_hash(child_name, loader_data);
356 int p_index = placeholders()->hash_to_index(p_hash);
357 // can't throw error holding a lock
358 bool child_already_loaded = false;
359 bool throw_circularity_error = false;
360 {
361 MutexLocker mu(SystemDictionary_lock, THREAD);
362 Klass* childk = find_class(d_index, d_hash, child_name, loader_data);
363 Klass* quicksuperk;
364 // to support // loading: if child done loading, just return superclass
365 // if class_name, & class_loader don't match:
366 // if initial define, SD update will give LinkageError
367 // if redefine: compare_class_versions will give HIERARCHY_CHANGED
368 // so we don't throw an exception here.
369 // see: nsk redefclass014 & java.lang.instrument Instrument032
370 if ((childk != NULL ) && (is_superclass) &&
371 ((quicksuperk = childk->super()) != NULL) &&
372
373 ((quicksuperk->name() == class_name) &&
374 (quicksuperk->class_loader() == class_loader()))) {
375 return quicksuperk;
376 } else {
377 PlaceholderEntry* probe = placeholders()->get_entry(p_index, p_hash, child_name, loader_data);
378 if (probe && probe->check_seen_thread(THREAD, PlaceholderTable::LOAD_SUPER)) {
379 throw_circularity_error = true;
380 }
381 }
382 if (!throw_circularity_error) {
383 PlaceholderEntry* newprobe = placeholders()->find_and_add(p_index, p_hash, child_name, loader_data, PlaceholderTable::LOAD_SUPER, class_name, THREAD);
384 }
385 }
386 if (throw_circularity_error) {
387 ResourceMark rm(THREAD);
388 THROW_MSG_NULL(vmSymbols::java_lang_ClassCircularityError(), child_name->as_C_string());
389 }
390
391 // java.lang.Object should have been found above
392 assert(class_name != NULL, "null super class for resolving");
393 // Resolve the super class or interface, check results on return
394 Klass* superk = SystemDictionary::resolve_or_null(class_name,
395 class_loader,
396 protection_domain,
397 THREAD);
398
399 KlassHandle superk_h(THREAD, superk);
400
401 // Clean up of placeholders moved so that each classloadAction registrar self-cleans up
402 // It is no longer necessary to keep the placeholder table alive until update_dictionary
403 // or error. GC used to walk the placeholder table as strong roots.
404 // The instanceKlass is kept alive because the class loader is on the stack,
405 // which keeps the loader_data alive, as well as all instanceKlasses in
406 // the loader_data. parseClassFile adds the instanceKlass to loader_data.
407 {
408 MutexLocker mu(SystemDictionary_lock, THREAD);
409 placeholders()->find_and_remove(p_index, p_hash, child_name, loader_data, PlaceholderTable::LOAD_SUPER, THREAD);
410 SystemDictionary_lock->notify_all();
411 }
412 if (HAS_PENDING_EXCEPTION || superk_h() == NULL) {
413 // can null superk
414 superk_h = KlassHandle(THREAD, handle_resolution_exception(class_name, true, superk_h, THREAD));
415 }
416
417 return superk_h();
418 }
419
420 void SystemDictionary::validate_protection_domain(instanceKlassHandle klass,
421 Handle class_loader,
422 Handle protection_domain,
423 TRAPS) {
424 if(!has_checkPackageAccess()) return;
425
426 // Now we have to call back to java to check if the initating class has access
427 JavaValue result(T_VOID);
428 if (TraceProtectionDomainVerification) {
429 // Print out trace information
430 tty->print_cr("Checking package access");
431 tty->print(" - class loader: "); class_loader()->print_value_on(tty); tty->cr();
432 tty->print(" - protection domain: "); protection_domain()->print_value_on(tty); tty->cr();
433 tty->print(" - loading: "); klass()->print_value_on(tty); tty->cr();
434 }
435
436 KlassHandle system_loader(THREAD, SystemDictionary::ClassLoader_klass());
437 JavaCalls::call_special(&result,
438 class_loader,
439 system_loader,
440 vmSymbols::checkPackageAccess_name(),
441 vmSymbols::class_protectiondomain_signature(),
442 Handle(THREAD, klass->java_mirror()),
443 protection_domain,
444 THREAD);
445
446 if (TraceProtectionDomainVerification) {
447 if (HAS_PENDING_EXCEPTION) {
448 tty->print_cr(" -> DENIED !!!!!!!!!!!!!!!!!!!!!");
449 } else {
450 tty->print_cr(" -> granted");
451 }
452 tty->cr();
453 }
454
455 if (HAS_PENDING_EXCEPTION) return;
456
457 // If no exception has been thrown, we have validated the protection domain
458 // Insert the protection domain of the initiating class into the set.
459 {
460 // We recalculate the entry here -- we've called out to java since
461 // the last time it was calculated.
462 ClassLoaderData* loader_data = class_loader_data(class_loader);
463
464 Symbol* kn = klass->name();
465 unsigned int d_hash = dictionary()->compute_hash(kn, loader_data);
466 int d_index = dictionary()->hash_to_index(d_hash);
467
468 MutexLocker mu(SystemDictionary_lock, THREAD);
469 {
470 // Note that we have an entry, and entries can be deleted only during GC,
471 // so we cannot allow GC to occur while we're holding this entry.
472
473 // We're using a No_Safepoint_Verifier to catch any place where we
474 // might potentially do a GC at all.
475 // Dictionary::do_unloading() asserts that classes in SD are only
476 // unloaded at a safepoint. Anonymous classes are not in SD.
477 No_Safepoint_Verifier nosafepoint;
478 dictionary()->add_protection_domain(d_index, d_hash, klass, loader_data,
479 protection_domain, THREAD);
480 }
481 }
482 }
483
484 // We only get here if this thread finds that another thread
485 // has already claimed the placeholder token for the current operation,
486 // but that other thread either never owned or gave up the
487 // object lock
488 // Waits on SystemDictionary_lock to indicate placeholder table updated
489 // On return, caller must recheck placeholder table state
490 //
491 // We only get here if
492 // 1) custom classLoader, i.e. not bootstrap classloader
493 // 2) UnsyncloadClass not set
494 // 3) custom classLoader has broken the class loader objectLock
495 // so another thread got here in parallel
496 //
497 // lockObject must be held.
498 // Complicated dance due to lock ordering:
499 // Must first release the classloader object lock to
500 // allow initial definer to complete the class definition
501 // and to avoid deadlock
502 // Reclaim classloader lock object with same original recursion count
503 // Must release SystemDictionary_lock after notify, since
504 // class loader lock must be claimed before SystemDictionary_lock
505 // to prevent deadlocks
506 //
507 // The notify allows applications that did an untimed wait() on
508 // the classloader object lock to not hang.
509 void SystemDictionary::double_lock_wait(Handle lockObject, TRAPS) {
510 assert_lock_strong(SystemDictionary_lock);
511
512 bool calledholdinglock
513 = ObjectSynchronizer::current_thread_holds_lock((JavaThread*)THREAD, lockObject);
514 assert(calledholdinglock,"must hold lock for notify");
515 assert((!(lockObject() == _system_loader_lock_obj) && !is_parallelCapable(lockObject)), "unexpected double_lock_wait");
516 ObjectSynchronizer::notifyall(lockObject, THREAD);
517 intptr_t recursions = ObjectSynchronizer::complete_exit(lockObject, THREAD);
518 SystemDictionary_lock->wait();
519 SystemDictionary_lock->unlock();
520 ObjectSynchronizer::reenter(lockObject, recursions, THREAD);
521 SystemDictionary_lock->lock();
522 }
523
524 // If the class in is in the placeholder table, class loading is in progress
525 // For cases where the application changes threads to load classes, it
526 // is critical to ClassCircularity detection that we try loading
527 // the superclass on the same thread internally, so we do parallel
528 // super class loading here.
529 // This also is critical in cases where the original thread gets stalled
530 // even in non-circularity situations.
531 // Note: must call resolve_super_or_fail even if null super -
532 // to force placeholder entry creation for this class for circularity detection
533 // Caller must check for pending exception
534 // Returns non-null Klass* if other thread has completed load
535 // and we are done,
536 // If return null Klass* and no pending exception, the caller must load the class
537 instanceKlassHandle SystemDictionary::handle_parallel_super_load(
538 Symbol* name, Symbol* superclassname, Handle class_loader,
539 Handle protection_domain, Handle lockObject, TRAPS) {
540
541 instanceKlassHandle nh = instanceKlassHandle(); // null Handle
542 ClassLoaderData* loader_data = class_loader_data(class_loader);
543 unsigned int d_hash = dictionary()->compute_hash(name, loader_data);
544 int d_index = dictionary()->hash_to_index(d_hash);
545 unsigned int p_hash = placeholders()->compute_hash(name, loader_data);
546 int p_index = placeholders()->hash_to_index(p_hash);
547
548 // superk is not used, resolve_super called for circularity check only
549 // This code is reached in two situations. One if this thread
550 // is loading the same class twice (e.g. ClassCircularity, or
551 // java.lang.instrument).
552 // The second is if another thread started the resolve_super first
553 // and has not yet finished.
554 // In both cases the original caller will clean up the placeholder
555 // entry on error.
556 Klass* superk = SystemDictionary::resolve_super_or_fail(name,
557 superclassname,
558 class_loader,
559 protection_domain,
560 true,
561 CHECK_(nh));
562
563 // parallelCapable class loaders do NOT wait for parallel superclass loads to complete
564 // Serial class loaders and bootstrap classloader do wait for superclass loads
565 if (!class_loader.is_null() && is_parallelCapable(class_loader)) {
566 MutexLocker mu(SystemDictionary_lock, THREAD);
567 // Check if classloading completed while we were loading superclass or waiting
568 Klass* check = find_class(d_index, d_hash, name, loader_data);
569 if (check != NULL) {
570 // Klass is already loaded, so just return it
571 return(instanceKlassHandle(THREAD, check));
572 } else {
573 return nh;
574 }
575 }
576
577 // must loop to both handle other placeholder updates
578 // and spurious notifications
579 bool super_load_in_progress = true;
580 PlaceholderEntry* placeholder;
581 while (super_load_in_progress) {
582 MutexLocker mu(SystemDictionary_lock, THREAD);
583 // Check if classloading completed while we were loading superclass or waiting
584 Klass* check = find_class(d_index, d_hash, name, loader_data);
585 if (check != NULL) {
586 // Klass is already loaded, so just return it
587 return(instanceKlassHandle(THREAD, check));
588 } else {
589 placeholder = placeholders()->get_entry(p_index, p_hash, name, loader_data);
590 if (placeholder && placeholder->super_load_in_progress() ){
591 // Before UnsyncloadClass:
592 // We only get here if the application has released the
593 // classloader lock when another thread was in the middle of loading a
594 // superclass/superinterface for this class, and now
595 // this thread is also trying to load this class.
596 // To minimize surprises, the first thread that started to
597 // load a class should be the one to complete the loading
598 // with the classfile it initially expected.
599 // This logic has the current thread wait once it has done
600 // all the superclass/superinterface loading it can, until
601 // the original thread completes the class loading or fails
602 // If it completes we will use the resulting InstanceKlass
603 // which we will find below in the systemDictionary.
604 // We also get here for parallel bootstrap classloader
605 if (class_loader.is_null()) {
606 SystemDictionary_lock->wait();
607 } else {
608 double_lock_wait(lockObject, THREAD);
609 }
610 } else {
611 // If not in SD and not in PH, other thread's load must have failed
612 super_load_in_progress = false;
613 }
614 }
615 }
616 return (nh);
617 }
618
619
620 Klass* SystemDictionary::resolve_instance_class_or_null(Symbol* name,
621 Handle class_loader,
622 Handle protection_domain,
623 TRAPS) {
624 assert(name != NULL && !FieldType::is_array(name) &&
625 !FieldType::is_obj(name), "invalid class name");
626
627 Ticks class_load_start_time = Ticks::now();
628
629 // Fix for 4474172; see evaluation for more details
630 class_loader = Handle(THREAD, java_lang_ClassLoader::non_reflection_class_loader(class_loader()));
631 ClassLoaderData *loader_data = register_loader(class_loader, CHECK_NULL);
632
633 // Do lookup to see if class already exist and the protection domain
634 // has the right access
635 // This call uses find which checks protection domain already matches
636 // All subsequent calls use find_class, and set has_loaded_class so that
637 // before we return a result we call out to java to check for valid protection domain
638 // to allow returning the Klass* and add it to the pd_set if it is valid
639 unsigned int d_hash = dictionary()->compute_hash(name, loader_data);
640 int d_index = dictionary()->hash_to_index(d_hash);
641 Klass* probe = dictionary()->find(d_index, d_hash, name, loader_data,
642 protection_domain, THREAD);
643 if (probe != NULL) return probe;
644
645
646 // Non-bootstrap class loaders will call out to class loader and
647 // define via jvm/jni_DefineClass which will acquire the
648 // class loader object lock to protect against multiple threads
649 // defining the class in parallel by accident.
650 // This lock must be acquired here so the waiter will find
651 // any successful result in the SystemDictionary and not attempt
652 // the define
653 // ParallelCapable Classloaders and the bootstrap classloader,
654 // or all classloaders with UnsyncloadClass do not acquire lock here
655 bool DoObjectLock = true;
656 if (is_parallelCapable(class_loader)) {
657 DoObjectLock = false;
658 }
659
660 unsigned int p_hash = placeholders()->compute_hash(name, loader_data);
661 int p_index = placeholders()->hash_to_index(p_hash);
662
663 // Class is not in SystemDictionary so we have to do loading.
664 // Make sure we are synchronized on the class loader before we proceed
665 Handle lockObject = compute_loader_lock_object(class_loader, THREAD);
666 check_loader_lock_contention(lockObject, THREAD);
667 ObjectLocker ol(lockObject, THREAD, DoObjectLock);
668
669 // Check again (after locking) if class already exist in SystemDictionary
670 bool class_has_been_loaded = false;
671 bool super_load_in_progress = false;
672 bool havesupername = false;
673 instanceKlassHandle k;
674 PlaceholderEntry* placeholder;
675 Symbol* superclassname = NULL;
676
677 {
678 MutexLocker mu(SystemDictionary_lock, THREAD);
679 Klass* check = find_class(d_index, d_hash, name, loader_data);
680 if (check != NULL) {
681 // Klass is already loaded, so just return it
682 class_has_been_loaded = true;
683 k = instanceKlassHandle(THREAD, check);
684 } else {
685 placeholder = placeholders()->get_entry(p_index, p_hash, name, loader_data);
686 if (placeholder && placeholder->super_load_in_progress()) {
687 super_load_in_progress = true;
688 if (placeholder->havesupername() == true) {
689 superclassname = placeholder->supername();
690 havesupername = true;
691 }
692 }
693 }
694 }
695
696 // If the class is in the placeholder table, class loading is in progress
697 if (super_load_in_progress && havesupername==true) {
698 k = SystemDictionary::handle_parallel_super_load(name, superclassname,
699 class_loader, protection_domain, lockObject, THREAD);
700 if (HAS_PENDING_EXCEPTION) {
701 return NULL;
702 }
703 if (!k.is_null()) {
704 class_has_been_loaded = true;
705 }
706 }
707
708 bool throw_circularity_error = false;
709 if (!class_has_been_loaded) {
710 bool load_instance_added = false;
711
712 // add placeholder entry to record loading instance class
713 // Five cases:
714 // All cases need to prevent modifying bootclasssearchpath
715 // in parallel with a classload of same classname
716 // Redefineclasses uses existence of the placeholder for the duration
717 // of the class load to prevent concurrent redefinition of not completely
718 // defined classes.
719 // case 1. traditional classloaders that rely on the classloader object lock
720 // - no other need for LOAD_INSTANCE
721 // case 2. traditional classloaders that break the classloader object lock
722 // as a deadlock workaround. Detection of this case requires that
723 // this check is done while holding the classloader object lock,
724 // and that lock is still held when calling classloader's loadClass.
725 // For these classloaders, we ensure that the first requestor
726 // completes the load and other requestors wait for completion.
727 // case 3. UnsyncloadClass - don't use objectLocker
728 // With this flag, we allow parallel classloading of a
729 // class/classloader pair
730 // case4. Bootstrap classloader - don't own objectLocker
731 // This classloader supports parallelism at the classloader level,
732 // but only allows a single load of a class/classloader pair.
733 // No performance benefit and no deadlock issues.
734 // case 5. parallelCapable user level classloaders - without objectLocker
735 // Allow parallel classloading of a class/classloader pair
736
737 {
738 MutexLocker mu(SystemDictionary_lock, THREAD);
739 if (class_loader.is_null() || !is_parallelCapable(class_loader)) {
740 PlaceholderEntry* oldprobe = placeholders()->get_entry(p_index, p_hash, name, loader_data);
741 if (oldprobe) {
742 // only need check_seen_thread once, not on each loop
743 // 6341374 java/lang/Instrument with -Xcomp
744 if (oldprobe->check_seen_thread(THREAD, PlaceholderTable::LOAD_INSTANCE)) {
745 throw_circularity_error = true;
746 } else {
747 // case 1: traditional: should never see load_in_progress.
748 while (!class_has_been_loaded && oldprobe && oldprobe->instance_load_in_progress()) {
749
750 // case 4: bootstrap classloader: prevent futile classloading,
751 // wait on first requestor
752 if (class_loader.is_null()) {
753 SystemDictionary_lock->wait();
754 } else {
755 // case 2: traditional with broken classloader lock. wait on first
756 // requestor.
757 double_lock_wait(lockObject, THREAD);
758 }
759 // Check if classloading completed while we were waiting
760 Klass* check = find_class(d_index, d_hash, name, loader_data);
761 if (check != NULL) {
762 // Klass is already loaded, so just return it
763 k = instanceKlassHandle(THREAD, check);
764 class_has_been_loaded = true;
765 }
766 // check if other thread failed to load and cleaned up
767 oldprobe = placeholders()->get_entry(p_index, p_hash, name, loader_data);
768 }
769 }
770 }
771 }
772 // All cases: add LOAD_INSTANCE holding SystemDictionary_lock
773 // case 3: UnsyncloadClass || case 5: parallelCapable: allow competing threads to try
774 // LOAD_INSTANCE in parallel
775
776 if (!throw_circularity_error && !class_has_been_loaded) {
777 PlaceholderEntry* newprobe = placeholders()->find_and_add(p_index, p_hash, name, loader_data, PlaceholderTable::LOAD_INSTANCE, NULL, THREAD);
778 load_instance_added = true;
779 // For class loaders that do not acquire the classloader object lock,
780 // if they did not catch another thread holding LOAD_INSTANCE,
781 // need a check analogous to the acquire ObjectLocker/find_class
782 // i.e. now that we hold the LOAD_INSTANCE token on loading this class/CL
783 // one final check if the load has already completed
784 // class loaders holding the ObjectLock shouldn't find the class here
785 Klass* check = find_class(d_index, d_hash, name, loader_data);
786 if (check != NULL) {
787 // Klass is already loaded, so return it after checking/adding protection domain
788 k = instanceKlassHandle(THREAD, check);
789 class_has_been_loaded = true;
790 }
791 }
792 }
793
794 // must throw error outside of owning lock
795 if (throw_circularity_error) {
796 assert(!HAS_PENDING_EXCEPTION && load_instance_added == false,"circularity error cleanup");
797 ResourceMark rm(THREAD);
798 THROW_MSG_NULL(vmSymbols::java_lang_ClassCircularityError(), name->as_C_string());
799 }
800
801 if (!class_has_been_loaded) {
802
803 // Do actual loading
804 k = load_instance_class(name, class_loader, THREAD);
805
806 // For UnsyncloadClass only
807 // If they got a linkageError, check if a parallel class load succeeded.
808 // If it did, then for bytecode resolution the specification requires
809 // that we return the same result we did for the other thread, i.e. the
810 // successfully loaded InstanceKlass
811 // Should not get here for classloaders that support parallelism
812 // with the new cleaner mechanism, even with AllowParallelDefineClass
813 // Bootstrap goes through here to allow for an extra guarantee check
814 if (UnsyncloadClass || (class_loader.is_null())) {
815 if (k.is_null() && HAS_PENDING_EXCEPTION
816 && PENDING_EXCEPTION->is_a(SystemDictionary::LinkageError_klass())) {
817 MutexLocker mu(SystemDictionary_lock, THREAD);
818 Klass* check = find_class(d_index, d_hash, name, loader_data);
819 if (check != NULL) {
820 // Klass is already loaded, so just use it
821 k = instanceKlassHandle(THREAD, check);
822 CLEAR_PENDING_EXCEPTION;
823 guarantee((!class_loader.is_null()), "dup definition for bootstrap loader?");
824 }
825 }
826 }
827
828 // If everything was OK (no exceptions, no null return value), and
829 // class_loader is NOT the defining loader, do a little more bookkeeping.
830 if (!HAS_PENDING_EXCEPTION && !k.is_null() &&
831 k->class_loader() != class_loader()) {
832
833 check_constraints(d_index, d_hash, k, class_loader, false, THREAD);
834
835 // Need to check for a PENDING_EXCEPTION again; check_constraints
836 // can throw and doesn't use the CHECK macro.
837 if (!HAS_PENDING_EXCEPTION) {
838 { // Grabbing the Compile_lock prevents systemDictionary updates
839 // during compilations.
840 MutexLocker mu(Compile_lock, THREAD);
841 update_dictionary(d_index, d_hash, p_index, p_hash,
842 k, class_loader, THREAD);
843 }
844
845 if (JvmtiExport::should_post_class_load()) {
846 Thread *thread = THREAD;
847 assert(thread->is_Java_thread(), "thread->is_Java_thread()");
848 JvmtiExport::post_class_load((JavaThread *) thread, k());
849 }
850 }
851 }
852 } // load_instance_class loop
853
854 if (load_instance_added == true) {
855 // clean up placeholder entries for LOAD_INSTANCE success or error
856 // This brackets the SystemDictionary updates for both defining
857 // and initiating loaders
858 MutexLocker mu(SystemDictionary_lock, THREAD);
859 placeholders()->find_and_remove(p_index, p_hash, name, loader_data, PlaceholderTable::LOAD_INSTANCE, THREAD);
860 SystemDictionary_lock->notify_all();
861 }
862 }
863
864 if (HAS_PENDING_EXCEPTION || k.is_null()) {
865 return NULL;
866 }
867
868 post_class_load_event(class_load_start_time, k, class_loader);
869
870 #ifdef ASSERT
871 {
872 ClassLoaderData* loader_data = k->class_loader_data();
873 MutexLocker mu(SystemDictionary_lock, THREAD);
874 Klass* kk = find_class(name, loader_data);
875 assert(kk == k(), "should be present in dictionary");
876 }
877 #endif
878
879 // return if the protection domain in NULL
880 if (protection_domain() == NULL) return k();
881
882 // Check the protection domain has the right access
883 {
884 MutexLocker mu(SystemDictionary_lock, THREAD);
885 // Note that we have an entry, and entries can be deleted only during GC,
886 // so we cannot allow GC to occur while we're holding this entry.
887 // We're using a No_Safepoint_Verifier to catch any place where we
888 // might potentially do a GC at all.
889 // Dictionary::do_unloading() asserts that classes in SD are only
890 // unloaded at a safepoint. Anonymous classes are not in SD.
891 No_Safepoint_Verifier nosafepoint;
892 if (dictionary()->is_valid_protection_domain(d_index, d_hash, name,
893 loader_data,
894 protection_domain)) {
895 return k();
896 }
897 }
898
899 // Verify protection domain. If it fails an exception is thrown
900 validate_protection_domain(k, class_loader, protection_domain, CHECK_NULL);
901
902 return k();
903 }
904
905
906 // This routine does not lock the system dictionary.
907 //
908 // Since readers don't hold a lock, we must make sure that system
909 // dictionary entries are only removed at a safepoint (when only one
910 // thread is running), and are added to in a safe way (all links must
911 // be updated in an MT-safe manner).
912 //
913 // Callers should be aware that an entry could be added just after
914 // _dictionary->bucket(index) is read here, so the caller will not see
915 // the new entry.
916
917 Klass* SystemDictionary::find(Symbol* class_name,
918 Handle class_loader,
919 Handle protection_domain,
920 TRAPS) {
921
922 // The result of this call should be consistent with the result
923 // of the call to resolve_instance_class_or_null().
924 // See evaluation 6790209 and 4474172 for more details.
925 class_loader = Handle(THREAD, java_lang_ClassLoader::non_reflection_class_loader(class_loader()));
926 ClassLoaderData* loader_data = ClassLoaderData::class_loader_data_or_null(class_loader());
927
928 if (loader_data == NULL) {
929 // If the ClassLoaderData has not been setup,
930 // then the class loader has no entries in the dictionary.
931 return NULL;
932 }
933
934 unsigned int d_hash = dictionary()->compute_hash(class_name, loader_data);
935 int d_index = dictionary()->hash_to_index(d_hash);
936
937 {
938 // Note that we have an entry, and entries can be deleted only during GC,
939 // so we cannot allow GC to occur while we're holding this entry.
940 // We're using a No_Safepoint_Verifier to catch any place where we
941 // might potentially do a GC at all.
942 // Dictionary::do_unloading() asserts that classes in SD are only
943 // unloaded at a safepoint. Anonymous classes are not in SD.
944 No_Safepoint_Verifier nosafepoint;
945 return dictionary()->find(d_index, d_hash, class_name, loader_data,
946 protection_domain, THREAD);
947 }
948 }
949
950
951 // Look for a loaded instance or array klass by name. Do not do any loading.
952 // return NULL in case of error.
953 Klass* SystemDictionary::find_instance_or_array_klass(Symbol* class_name,
954 Handle class_loader,
955 Handle protection_domain,
956 TRAPS) {
957 Klass* k = NULL;
958 assert(class_name != NULL, "class name must be non NULL");
959
960 if (FieldType::is_array(class_name)) {
961 // The name refers to an array. Parse the name.
962 // dimension and object_key in FieldArrayInfo are assigned as a
963 // side-effect of this call
964 FieldArrayInfo fd;
965 BasicType t = FieldType::get_array_info(class_name, fd, CHECK_(NULL));
966 if (t != T_OBJECT) {
967 k = Universe::typeArrayKlassObj(t);
968 } else {
969 k = SystemDictionary::find(fd.object_key(), class_loader, protection_domain, THREAD);
970 }
971 if (k != NULL) {
972 k = k->array_klass_or_null(fd.dimension());
973 }
974 } else {
975 k = find(class_name, class_loader, protection_domain, THREAD);
976 }
977 return k;
978 }
979
980 // Note: this method is much like resolve_from_stream, but
981 // updates no supplemental data structures.
982 // TODO consolidate the two methods with a helper routine?
983 Klass* SystemDictionary::parse_stream(Symbol* class_name,
984 Handle class_loader,
985 Handle protection_domain,
986 ClassFileStream* st,
987 KlassHandle host_klass,
988 GrowableArray<Handle>* cp_patches,
989 TRAPS) {
990 TempNewSymbol parsed_name = NULL;
991
992 Ticks class_load_start_time = Ticks::now();
993
994 ClassLoaderData* loader_data;
995 if (host_klass.not_null()) {
996 // Create a new CLD for anonymous class, that uses the same class loader
997 // as the host_klass
998 guarantee(host_klass->class_loader() == class_loader(), "should be the same");
999 guarantee(!DumpSharedSpaces, "must not create anonymous classes when dumping");
1000 loader_data = ClassLoaderData::anonymous_class_loader_data(class_loader(), CHECK_NULL);
1001 loader_data->record_dependency(host_klass(), CHECK_NULL);
1002 } else {
1003 loader_data = ClassLoaderData::class_loader_data(class_loader());
1004 }
1005
1006 // Parse the stream. Note that we do this even though this klass might
1007 // already be present in the SystemDictionary, otherwise we would not
1008 // throw potential ClassFormatErrors.
1009 //
1010 // Note: "name" is updated.
1011
1012 instanceKlassHandle k = ClassFileParser(st).parseClassFile(class_name,
1013 loader_data,
1014 protection_domain,
1015 host_klass,
1016 cp_patches,
1017 parsed_name,
1018 true,
1019 THREAD);
1020
1021
1022 if (host_klass.not_null() && k.not_null()) {
1023 // If it's anonymous, initialize it now, since nobody else will.
1024
1025 {
1026 MutexLocker mu_r(Compile_lock, THREAD);
1027
1028 // Add to class hierarchy, initialize vtables, and do possible
1029 // deoptimizations.
1030 add_to_hierarchy(k, CHECK_NULL); // No exception, but can block
1031
1032 // But, do not add to system dictionary.
1033
1034 // compiled code dependencies need to be validated anyway
1035 notice_modification();
1036 }
1037
1038 // Rewrite and patch constant pool here.
1039 k->link_class(CHECK_NULL);
1040 if (cp_patches != NULL) {
1041 k->constants()->patch_resolved_references(cp_patches);
1042 }
1043 k->eager_initialize(CHECK_NULL);
1044
1045 // notify jvmti
1046 if (JvmtiExport::should_post_class_load()) {
1047 assert(THREAD->is_Java_thread(), "thread->is_Java_thread()");
1048 JvmtiExport::post_class_load((JavaThread *) THREAD, k());
1049 }
1050
1051 post_class_load_event(class_load_start_time, k, class_loader);
1052 }
1053 assert(host_klass.not_null() || cp_patches == NULL,
1054 "cp_patches only found with host_klass");
1055
1056 return k();
1057 }
1058
1059 // Add a klass to the system from a stream (called by jni_DefineClass and
1060 // JVM_DefineClass).
1061 // Note: class_name can be NULL. In that case we do not know the name of
1062 // the class until we have parsed the stream.
1063
1064 Klass* SystemDictionary::resolve_from_stream(Symbol* class_name,
1065 Handle class_loader,
1066 Handle protection_domain,
1067 ClassFileStream* st,
1068 bool verify,
1069 TRAPS) {
1070
1071 // Classloaders that support parallelism, e.g. bootstrap classloader,
1072 // or all classloaders with UnsyncloadClass do not acquire lock here
1073 bool DoObjectLock = true;
1074 if (is_parallelCapable(class_loader)) {
1075 DoObjectLock = false;
1076 }
1077
1078 ClassLoaderData* loader_data = register_loader(class_loader, CHECK_NULL);
1079
1080 // Make sure we are synchronized on the class loader before we proceed
1081 Handle lockObject = compute_loader_lock_object(class_loader, THREAD);
1082 check_loader_lock_contention(lockObject, THREAD);
1083 ObjectLocker ol(lockObject, THREAD, DoObjectLock);
1084
1085 #if INCLUDE_CDS
1086 instanceKlassHandle sk =
1087 SystemDictionaryShared::resolve_from_shared_space(class_name,
1088 class_loader,
1089 protection_domain,
1090 st,
1091 verify,
1092 CHECK_NULL);
1093 if (sk.not_null()) {
1094 assert(MetaspaceShared::is_in_shared_space(sk()), "must be");
1095
1096 // Make sure we have an entry in the SystemDictionary on success
1097 debug_only( {
1098 Symbol* h_name = sk->name();
1099 ClassLoaderData *defining_loader_data = sk->class_loader_data();
1100
1101 MutexLocker mu(SystemDictionary_lock, THREAD);
1102
1103 Klass* check = find_class(h_name, loader_data);
1104 assert(check == sk(), "should be present in the dictionary");
1105
1106 Klass* check2 = find_class(h_name, defining_loader_data);
1107 assert(check == check2, "name inconsistancy in SystemDictionary");
1108 } );
1109
1110 return sk();
1111 }
1112 #endif
1113
1114 TempNewSymbol parsed_name = NULL;
1115
1116 // Parse the stream. Note that we do this even though this klass might
1117 // already be present in the SystemDictionary, otherwise we would not
1118 // throw potential ClassFormatErrors.
1119 //
1120 // Note: "name" is updated.
1121
1122 instanceKlassHandle k = ClassFileParser(st).parseClassFile(class_name,
1123 loader_data,
1124 protection_domain,
1125 parsed_name,
1126 verify,
1127 THREAD);
1128
1129 const char* pkg = "java/";
1130 if (!HAS_PENDING_EXCEPTION &&
1131 !class_loader.is_null() &&
1132 parsed_name != NULL &&
1133 !strncmp((const char*)parsed_name->bytes(), pkg, strlen(pkg))) {
1134 // It is illegal to define classes in the "java." package from
1135 // JVM_DefineClass or jni_DefineClass unless you're the bootclassloader
1136 ResourceMark rm(THREAD);
1137 char* name = parsed_name->as_C_string();
1138 char* index = strrchr(name, '/');
1139 *index = '\0'; // chop to just the package name
1140 while ((index = strchr(name, '/')) != NULL) {
1141 *index = '.'; // replace '/' with '.' in package name
1142 }
1143 const char* fmt = "Prohibited package name: %s";
1144 size_t len = strlen(fmt) + strlen(name);
1145 char* message = NEW_RESOURCE_ARRAY(char, len);
1146 jio_snprintf(message, len, fmt, name);
1147 Exceptions::_throw_msg(THREAD_AND_LOCATION,
1148 vmSymbols::java_lang_SecurityException(), message);
1149 }
1150
1151 if (!HAS_PENDING_EXCEPTION) {
1152 assert(parsed_name != NULL, "Sanity");
1153 assert(class_name == NULL || class_name == parsed_name, "name mismatch");
1154 // Verification prevents us from creating names with dots in them, this
1155 // asserts that that's the case.
1156 assert(is_internal_format(parsed_name),
1157 "external class name format used internally");
1158
1159 // Add class just loaded
1160 // If a class loader supports parallel classloading handle parallel define requests
1161 // find_or_define_instance_class may return a different InstanceKlass
1162 if (is_parallelCapable(class_loader)) {
1163 k = find_or_define_instance_class(class_name, class_loader, k, THREAD);
1164 } else {
1165 define_instance_class(k, THREAD);
1166 }
1167 }
1168
1169 // Make sure we have an entry in the SystemDictionary on success
1170 debug_only( {
1171 if (!HAS_PENDING_EXCEPTION) {
1172 assert(parsed_name != NULL, "parsed_name is still null?");
1173 Symbol* h_name = k->name();
1174 ClassLoaderData *defining_loader_data = k->class_loader_data();
1175
1176 MutexLocker mu(SystemDictionary_lock, THREAD);
1177
1178 Klass* check = find_class(parsed_name, loader_data);
1179 assert(check == k(), "should be present in the dictionary");
1180
1181 Klass* check2 = find_class(h_name, defining_loader_data);
1182 assert(check == check2, "name inconsistancy in SystemDictionary");
1183 }
1184 } );
1185
1186 return k();
1187 }
1188
1189 #if INCLUDE_CDS
1190 void SystemDictionary::set_shared_dictionary(HashtableBucket<mtClass>* t, int length,
1191 int number_of_entries) {
1192 assert(length == _nof_buckets * sizeof(HashtableBucket<mtClass>),
1193 "bad shared dictionary size.");
1194 _shared_dictionary = new Dictionary(_nof_buckets, t, number_of_entries);
1195 }
1196
1197
1198 // If there is a shared dictionary, then find the entry for the
1199 // given shared system class, if any.
1200
1201 Klass* SystemDictionary::find_shared_class(Symbol* class_name) {
1202 if (shared_dictionary() != NULL) {
1203 unsigned int d_hash = shared_dictionary()->compute_hash(class_name, NULL);
1204 int d_index = shared_dictionary()->hash_to_index(d_hash);
1205
1206 return shared_dictionary()->find_shared_class(d_index, d_hash, class_name);
1207 } else {
1208 return NULL;
1209 }
1210 }
1211
1212
1213 // Load a class from the shared spaces (found through the shared system
1214 // dictionary). Force the superclass and all interfaces to be loaded.
1215 // Update the class definition to include sibling classes and no
1216 // subclasses (yet). [Classes in the shared space are not part of the
1217 // object hierarchy until loaded.]
1218
1219 instanceKlassHandle SystemDictionary::load_shared_class(
1220 Symbol* class_name, Handle class_loader, TRAPS) {
1221 instanceKlassHandle ik (THREAD, find_shared_class(class_name));
1222 // Make sure we only return the boot class for the NULL classloader.
1223 if (ik.not_null() &&
1224 SharedClassUtil::is_shared_boot_class(ik()) && class_loader.is_null()) {
1225 Handle protection_domain;
1226 return load_shared_class(ik, class_loader, protection_domain, THREAD);
1227 }
1228 return instanceKlassHandle();
1229 }
1230
1231 instanceKlassHandle SystemDictionary::load_shared_class(instanceKlassHandle ik,
1232 Handle class_loader,
1233 Handle protection_domain, TRAPS) {
1234 if (ik.not_null()) {
1235 instanceKlassHandle nh = instanceKlassHandle(); // null Handle
1236 Symbol* class_name = ik->name();
1237
1238 // Found the class, now load the superclass and interfaces. If they
1239 // are shared, add them to the main system dictionary and reset
1240 // their hierarchy references (supers, subs, and interfaces).
1241
1242 if (ik->super() != NULL) {
1243 Symbol* cn = ik->super()->name();
1244 Klass *s = resolve_super_or_fail(class_name, cn,
1245 class_loader, protection_domain, true, CHECK_(nh));
1246 if (s != ik->super()) {
1247 // The dynamically resolved super class is not the same as the one we used during dump time,
1248 // so we cannot use ik.
1249 return nh;
1250 }
1251 }
1252
1253 Array<Klass*>* interfaces = ik->local_interfaces();
1254 int num_interfaces = interfaces->length();
1255 for (int index = 0; index < num_interfaces; index++) {
1256 Klass* k = interfaces->at(index);
1257
1258 // Note: can not use InstanceKlass::cast here because
1259 // interfaces' InstanceKlass's C++ vtbls haven't been
1260 // reinitialized yet (they will be once the interface classes
1261 // are loaded)
1262 Symbol* name = k->name();
1263 Klass* i = resolve_super_or_fail(class_name, name, class_loader, protection_domain, false, CHECK_(nh));
1264 if (k != i) {
1265 // The dynamically resolved interface class is not the same as the one we used during dump time,
1266 // so we cannot use ik.
1267 return nh;
1268 }
1269 }
1270
1271 // Adjust methods to recover missing data. They need addresses for
1272 // interpreter entry points and their default native method address
1273 // must be reset.
1274
1275 // Updating methods must be done under a lock so multiple
1276 // threads don't update these in parallel
1277 //
1278 // Shared classes are all currently loaded by either the bootstrap or
1279 // internal parallel class loaders, so this will never cause a deadlock
1280 // on a custom class loader lock.
1281
1282 ClassLoaderData* loader_data = ClassLoaderData::class_loader_data(class_loader());
1283 {
1284 Handle lockObject = compute_loader_lock_object(class_loader, THREAD);
1285 check_loader_lock_contention(lockObject, THREAD);
1286 ObjectLocker ol(lockObject, THREAD, true);
1287 ik->restore_unshareable_info(loader_data, protection_domain, CHECK_(nh));
1288 }
1289
1290 if (TraceClassLoading) {
1291 ResourceMark rm;
1292 tty->print("[Loaded %s", ik->external_name());
1293 tty->print(" from shared objects file");
1294 if (class_loader.not_null()) {
1295 tty->print(" by %s", loader_data->loader_name());
1296 }
1297 tty->print_cr("]");
1298 }
1299
1300 if (DumpLoadedClassList != NULL && classlist_file->is_open()) {
1301 // Only dump the classes that can be stored into CDS archive
1302 if (SystemDictionaryShared::is_sharing_possible(loader_data)) {
1303 ResourceMark rm(THREAD);
1304 classlist_file->print_cr("%s", ik->name()->as_C_string());
1305 classlist_file->flush();
1306 }
1307 }
1308
1309 // notify a class loaded from shared object
1310 ClassLoadingService::notify_class_loaded(ik(), true /* shared class */);
1311 }
1312 return ik;
1313 }
1314 #endif // INCLUDE_CDS
1315
1316 instanceKlassHandle SystemDictionary::load_instance_class(Symbol* class_name, Handle class_loader, TRAPS) {
1317 instanceKlassHandle nh = instanceKlassHandle(); // null Handle
1318 if (class_loader.is_null()) {
1319
1320 // Search the shared system dictionary for classes preloaded into the
1321 // shared spaces.
1322 instanceKlassHandle k;
1323 {
1324 #if INCLUDE_CDS
1325 PerfTraceTime vmtimer(ClassLoader::perf_shared_classload_time());
1326 k = load_shared_class(class_name, class_loader, THREAD);
1327 #endif
1328 }
1329
1330 if (k.is_null()) {
1331 // Use VM class loader
1332 PerfTraceTime vmtimer(ClassLoader::perf_sys_classload_time());
1333 k = ClassLoader::load_classfile(class_name, CHECK_(nh));
1334 }
1335
1336 // find_or_define_instance_class may return a different InstanceKlass
1337 if (!k.is_null()) {
1338 k = find_or_define_instance_class(class_name, class_loader, k, CHECK_(nh));
1339 }
1340 return k;
1341 } else {
1342 // Use user specified class loader to load class. Call loadClass operation on class_loader.
1343 ResourceMark rm(THREAD);
1344
1345 assert(THREAD->is_Java_thread(), "must be a JavaThread");
1346 JavaThread* jt = (JavaThread*) THREAD;
1347
1348 PerfClassTraceTime vmtimer(ClassLoader::perf_app_classload_time(),
1349 ClassLoader::perf_app_classload_selftime(),
1350 ClassLoader::perf_app_classload_count(),
1351 jt->get_thread_stat()->perf_recursion_counts_addr(),
1352 jt->get_thread_stat()->perf_timers_addr(),
1353 PerfClassTraceTime::CLASS_LOAD);
1354
1355 Handle s = java_lang_String::create_from_symbol(class_name, CHECK_(nh));
1356 // Translate to external class name format, i.e., convert '/' chars to '.'
1357 Handle string = java_lang_String::externalize_classname(s, CHECK_(nh));
1358
1359 JavaValue result(T_OBJECT);
1360
1361 KlassHandle spec_klass (THREAD, SystemDictionary::ClassLoader_klass());
1362
1363 // Call public unsynchronized loadClass(String) directly for all class loaders
1364 // for parallelCapable class loaders. JDK >=7, loadClass(String, boolean) will
1365 // acquire a class-name based lock rather than the class loader object lock.
1366 // JDK < 7 already acquire the class loader lock in loadClass(String, boolean),
1367 // so the call to loadClassInternal() was not required.
1368 //
1369 // UnsyncloadClass flag means both call loadClass(String) and do
1370 // not acquire the class loader lock even for class loaders that are
1371 // not parallelCapable. This was a risky transitional
1372 // flag for diagnostic purposes only. It is risky to call
1373 // custom class loaders without synchronization.
1374 // WARNING If a custom class loader does NOT synchronizer findClass, or callers of
1375 // findClass, the UnsyncloadClass flag risks unexpected timing bugs in the field.
1376 // Do NOT assume this will be supported in future releases.
1377 //
1378 // Added MustCallLoadClassInternal in case we discover in the field
1379 // a customer that counts on this call
1380 if (MustCallLoadClassInternal && has_loadClassInternal()) {
1381 JavaCalls::call_special(&result,
1382 class_loader,
1383 spec_klass,
1384 vmSymbols::loadClassInternal_name(),
1385 vmSymbols::string_class_signature(),
1386 string,
1387 CHECK_(nh));
1388 } else {
1389 JavaCalls::call_virtual(&result,
1390 class_loader,
1391 spec_klass,
1392 vmSymbols::loadClass_name(),
1393 vmSymbols::string_class_signature(),
1394 string,
1395 CHECK_(nh));
1396 }
1397
1398 assert(result.get_type() == T_OBJECT, "just checking");
1399 oop obj = (oop) result.get_jobject();
1400
1401 // Primitive classes return null since forName() can not be
1402 // used to obtain any of the Class objects representing primitives or void
1403 if ((obj != NULL) && !(java_lang_Class::is_primitive(obj))) {
1404 instanceKlassHandle k =
1405 instanceKlassHandle(THREAD, java_lang_Class::as_Klass(obj));
1406 // For user defined Java class loaders, check that the name returned is
1407 // the same as that requested. This check is done for the bootstrap
1408 // loader when parsing the class file.
1409 if (class_name == k->name()) {
1410 return k;
1411 }
1412 }
1413 // Class is not found or has the wrong name, return NULL
1414 return nh;
1415 }
1416 }
1417
1418 void SystemDictionary::define_instance_class(instanceKlassHandle k, TRAPS) {
1419
1420 ClassLoaderData* loader_data = k->class_loader_data();
1421 Handle class_loader_h(THREAD, loader_data->class_loader());
1422
1423 // for bootstrap and other parallel classloaders don't acquire lock,
1424 // use placeholder token
1425 // If a parallelCapable class loader calls define_instance_class instead of
1426 // find_or_define_instance_class to get here, we have a timing
1427 // hole with systemDictionary updates and check_constraints
1428 if (!class_loader_h.is_null() && !is_parallelCapable(class_loader_h)) {
1429 assert(ObjectSynchronizer::current_thread_holds_lock((JavaThread*)THREAD,
1430 compute_loader_lock_object(class_loader_h, THREAD)),
1431 "define called without lock");
1432 }
1433
1434 // Check class-loading constraints. Throw exception if violation is detected.
1435 // Grabs and releases SystemDictionary_lock
1436 // The check_constraints/find_class call and update_dictionary sequence
1437 // must be "atomic" for a specific class/classloader pair so we never
1438 // define two different instanceKlasses for that class/classloader pair.
1439 // Existing classloaders will call define_instance_class with the
1440 // classloader lock held
1441 // Parallel classloaders will call find_or_define_instance_class
1442 // which will require a token to perform the define class
1443 Symbol* name_h = k->name();
1444 unsigned int d_hash = dictionary()->compute_hash(name_h, loader_data);
1445 int d_index = dictionary()->hash_to_index(d_hash);
1446 check_constraints(d_index, d_hash, k, class_loader_h, true, CHECK);
1447
1448 // Register class just loaded with class loader (placed in Vector)
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() != NULL) {
1454 methodHandle m(THREAD, Universe::loader_addClass_method());
1455 JavaValue result(T_VOID);
1456 JavaCallArguments args(class_loader_h);
1457 args.push_oop(Handle(THREAD, k->java_mirror()));
1458 JavaCalls::call(&result, m, &args, CHECK);
1459 }
1460
1461 // Add the new class. We need recompile lock during update of CHA.
1462 {
1463 unsigned int p_hash = placeholders()->compute_hash(name_h, loader_data);
1464 int p_index = placeholders()->hash_to_index(p_hash);
1465
1466 MutexLocker mu_r(Compile_lock, THREAD);
1467
1468 // Add to class hierarchy, initialize vtables, and do possible
1469 // deoptimizations.
1470 add_to_hierarchy(k, CHECK); // No exception, but can block
1471
1472 // Add to systemDictionary - so other classes can see it.
1473 // Grabs and releases SystemDictionary_lock
1474 update_dictionary(d_index, d_hash, p_index, p_hash,
1475 k, class_loader_h, THREAD);
1476 }
1477 k->eager_initialize(THREAD);
1478
1479 // notify jvmti
1480 if (JvmtiExport::should_post_class_load()) {
1481 assert(THREAD->is_Java_thread(), "thread->is_Java_thread()");
1482 JvmtiExport::post_class_load((JavaThread *) THREAD, k());
1483
1484 }
1485
1486 }
1487
1488 // Support parallel classloading
1489 // All parallel class loaders, including bootstrap classloader
1490 // lock a placeholder entry for this class/class_loader pair
1491 // to allow parallel defines of different classes for this class loader
1492 // With AllowParallelDefine flag==true, in case they do not synchronize around
1493 // FindLoadedClass/DefineClass, calls, we check for parallel
1494 // loading for them, wait if a defineClass is in progress
1495 // and return the initial requestor's results
1496 // This flag does not apply to the bootstrap classloader.
1497 // With AllowParallelDefine flag==false, call through to define_instance_class
1498 // which will throw LinkageError: duplicate class definition.
1499 // False is the requested default.
1500 // For better performance, the class loaders should synchronize
1501 // findClass(), i.e. FindLoadedClass/DefineClassIfAbsent or they
1502 // potentially waste time reading and parsing the bytestream.
1503 // Note: VM callers should ensure consistency of k/class_name,class_loader
1504 instanceKlassHandle SystemDictionary::find_or_define_instance_class(Symbol* class_name, Handle class_loader, instanceKlassHandle k, TRAPS) {
1505
1506 instanceKlassHandle nh = instanceKlassHandle(); // null Handle
1507 Symbol* name_h = k->name(); // passed in class_name may be null
1508 ClassLoaderData* loader_data = class_loader_data(class_loader);
1509
1510 unsigned int d_hash = dictionary()->compute_hash(name_h, loader_data);
1511 int d_index = dictionary()->hash_to_index(d_hash);
1512
1513 // Hold SD lock around find_class and placeholder creation for DEFINE_CLASS
1514 unsigned int p_hash = placeholders()->compute_hash(name_h, loader_data);
1515 int p_index = placeholders()->hash_to_index(p_hash);
1516 PlaceholderEntry* probe;
1517
1518 {
1519 MutexLocker mu(SystemDictionary_lock, THREAD);
1520 // First check if class already defined
1521 if (UnsyncloadClass || (is_parallelDefine(class_loader))) {
1522 Klass* check = find_class(d_index, d_hash, name_h, loader_data);
1523 if (check != NULL) {
1524 return(instanceKlassHandle(THREAD, check));
1525 }
1526 }
1527
1528 // Acquire define token for this class/classloader
1529 probe = placeholders()->find_and_add(p_index, p_hash, name_h, loader_data, PlaceholderTable::DEFINE_CLASS, NULL, THREAD);
1530 // Wait if another thread defining in parallel
1531 // All threads wait - even those that will throw duplicate class: otherwise
1532 // caller is surprised by LinkageError: duplicate, but findLoadedClass fails
1533 // if other thread has not finished updating dictionary
1534 while (probe->definer() != NULL) {
1535 SystemDictionary_lock->wait();
1536 }
1537 // Only special cases allow parallel defines and can use other thread's results
1538 // Other cases fall through, and may run into duplicate defines
1539 // caught by finding an entry in the SystemDictionary
1540 if ((UnsyncloadClass || is_parallelDefine(class_loader)) && (probe->instance_klass() != NULL)) {
1541 placeholders()->find_and_remove(p_index, p_hash, name_h, loader_data, PlaceholderTable::DEFINE_CLASS, THREAD);
1542 SystemDictionary_lock->notify_all();
1543 #ifdef ASSERT
1544 Klass* check = find_class(d_index, d_hash, name_h, loader_data);
1545 assert(check != NULL, "definer missed recording success");
1546 #endif
1547 return(instanceKlassHandle(THREAD, probe->instance_klass()));
1548 } else {
1549 // This thread will define the class (even if earlier thread tried and had an error)
1550 probe->set_definer(THREAD);
1551 }
1552 }
1553
1554 define_instance_class(k, THREAD);
1555
1556 Handle linkage_exception = Handle(); // null handle
1557
1558 // definer must notify any waiting threads
1559 {
1560 MutexLocker mu(SystemDictionary_lock, THREAD);
1561 PlaceholderEntry* probe = placeholders()->get_entry(p_index, p_hash, name_h, loader_data);
1562 assert(probe != NULL, "DEFINE_CLASS placeholder lost?");
1563 if (probe != NULL) {
1564 if (HAS_PENDING_EXCEPTION) {
1565 linkage_exception = Handle(THREAD,PENDING_EXCEPTION);
1566 CLEAR_PENDING_EXCEPTION;
1567 } else {
1568 probe->set_instance_klass(k());
1569 }
1570 probe->set_definer(NULL);
1571 placeholders()->find_and_remove(p_index, p_hash, name_h, loader_data, PlaceholderTable::DEFINE_CLASS, THREAD);
1572 SystemDictionary_lock->notify_all();
1573 }
1574 }
1575
1576 // Can't throw exception while holding lock due to rank ordering
1577 if (linkage_exception() != NULL) {
1578 THROW_OOP_(linkage_exception(), nh); // throws exception and returns
1579 }
1580
1581 return k;
1582 }
1583 Handle SystemDictionary::compute_loader_lock_object(Handle class_loader, TRAPS) {
1584 // If class_loader is NULL we synchronize on _system_loader_lock_obj
1585 if (class_loader.is_null()) {
1586 return Handle(THREAD, _system_loader_lock_obj);
1587 } else {
1588 return class_loader;
1589 }
1590 }
1591
1592 // This method is added to check how often we have to wait to grab loader
1593 // lock. The results are being recorded in the performance counters defined in
1594 // ClassLoader::_sync_systemLoaderLockContentionRate and
1595 // ClassLoader::_sync_nonSystemLoaderLockConteionRate.
1596 void SystemDictionary::check_loader_lock_contention(Handle loader_lock, TRAPS) {
1597 if (!UsePerfData) {
1598 return;
1599 }
1600
1601 assert(!loader_lock.is_null(), "NULL lock object");
1602
1603 if (ObjectSynchronizer::query_lock_ownership((JavaThread*)THREAD, loader_lock)
1604 == ObjectSynchronizer::owner_other) {
1605 // contention will likely happen, so increment the corresponding
1606 // contention counter.
1607 if (loader_lock() == _system_loader_lock_obj) {
1608 ClassLoader::sync_systemLoaderLockContentionRate()->inc();
1609 } else {
1610 ClassLoader::sync_nonSystemLoaderLockContentionRate()->inc();
1611 }
1612 }
1613 }
1614
1615 // ----------------------------------------------------------------------------
1616 // Lookup
1617
1618 Klass* SystemDictionary::find_class(int index, unsigned int hash,
1619 Symbol* class_name,
1620 ClassLoaderData* loader_data) {
1621 assert_locked_or_safepoint(SystemDictionary_lock);
1622 assert (index == dictionary()->index_for(class_name, loader_data),
1623 "incorrect index?");
1624
1625 Klass* k = dictionary()->find_class(index, hash, class_name, loader_data);
1626 return k;
1627 }
1628
1629
1630 // Basic find on classes in the midst of being loaded
1631 Symbol* SystemDictionary::find_placeholder(Symbol* class_name,
1632 ClassLoaderData* loader_data) {
1633 assert_locked_or_safepoint(SystemDictionary_lock);
1634 unsigned int p_hash = placeholders()->compute_hash(class_name, loader_data);
1635 int p_index = placeholders()->hash_to_index(p_hash);
1636 return placeholders()->find_entry(p_index, p_hash, class_name, loader_data);
1637 }
1638
1639
1640 // Used for assertions and verification only
1641 Klass* SystemDictionary::find_class(Symbol* class_name, ClassLoaderData* loader_data) {
1642 #ifndef ASSERT
1643 guarantee(VerifyBeforeGC ||
1644 VerifyDuringGC ||
1645 VerifyBeforeExit ||
1646 VerifyDuringStartup ||
1647 VerifyAfterGC, "too expensive");
1648 #endif
1649 assert_locked_or_safepoint(SystemDictionary_lock);
1650
1651 // First look in the loaded class array
1652 unsigned int d_hash = dictionary()->compute_hash(class_name, loader_data);
1653 int d_index = dictionary()->hash_to_index(d_hash);
1654 return find_class(d_index, d_hash, class_name, loader_data);
1655 }
1656
1657
1658 // Get the next class in the diictionary.
1659 Klass* SystemDictionary::try_get_next_class() {
1660 return dictionary()->try_get_next_class();
1661 }
1662
1663
1664 // ----------------------------------------------------------------------------
1665 // Update hierachy. This is done before the new klass has been added to the SystemDictionary. The Recompile_lock
1666 // is held, to ensure that the compiler is not using the class hierachy, and that deoptimization will kick in
1667 // before a new class is used.
1668
1669 void SystemDictionary::add_to_hierarchy(instanceKlassHandle k, TRAPS) {
1670 assert(k.not_null(), "just checking");
1671 assert_locked_or_safepoint(Compile_lock);
1672
1673 // Link into hierachy. Make sure the vtables are initialized before linking into
1674 k->append_to_sibling_list(); // add to superklass/sibling list
1675 k->process_interfaces(THREAD); // handle all "implements" declarations
1676 k->set_init_state(InstanceKlass::loaded);
1677 // Now flush all code that depended on old class hierarchy.
1678 // Note: must be done *after* linking k into the hierarchy (was bug 12/9/97)
1679 // Also, first reinitialize vtable because it may have gotten out of synch
1680 // while the new class wasn't connected to the class hierarchy.
1681 CodeCache::flush_dependents_on(k);
1682 }
1683
1684 // ----------------------------------------------------------------------------
1685 // GC support
1686
1687 // Following roots during mark-sweep is separated in two phases.
1688 //
1689 // The first phase follows preloaded classes and all other system
1690 // classes, since these will never get unloaded anyway.
1691 //
1692 // The second phase removes (unloads) unreachable classes from the
1693 // system dictionary and follows the remaining classes' contents.
1694
1695 void SystemDictionary::always_strong_oops_do(OopClosure* blk) {
1696 roots_oops_do(blk, NULL);
1697 }
1698
1699 void SystemDictionary::always_strong_classes_do(KlassClosure* closure) {
1700 // Follow all system classes and temporary placeholders in dictionary
1701 dictionary()->always_strong_classes_do(closure);
1702
1703 // Placeholders. These represent classes we're actively loading.
1704 placeholders()->classes_do(closure);
1705 }
1706
1707 // Calculate a "good" systemdictionary size based
1708 // on predicted or current loaded classes count
1709 int SystemDictionary::calculate_systemdictionary_size(int classcount) {
1710 int newsize = _old_default_sdsize;
1711 if ((classcount > 0) && !DumpSharedSpaces) {
1712 int desiredsize = classcount/_average_depth_goal;
1713 for (newsize = _primelist[_sdgeneration]; _sdgeneration < _prime_array_size -1;
1714 newsize = _primelist[++_sdgeneration]) {
1715 if (desiredsize <= newsize) {
1716 break;
1717 }
1718 }
1719 }
1720 return newsize;
1721 }
1722
1723 #ifdef ASSERT
1724 class VerifySDReachableAndLiveClosure : public OopClosure {
1725 private:
1726 BoolObjectClosure* _is_alive;
1727
1728 template <class T> void do_oop_work(T* p) {
1729 oop obj = oopDesc::load_decode_heap_oop(p);
1730 guarantee(_is_alive->do_object_b(obj), "Oop in system dictionary must be live");
1731 }
1732
1733 public:
1734 VerifySDReachableAndLiveClosure(BoolObjectClosure* is_alive) : OopClosure(), _is_alive(is_alive) { }
1735
1736 virtual void do_oop(oop* p) { do_oop_work(p); }
1737 virtual void do_oop(narrowOop* p) { do_oop_work(p); }
1738 };
1739 #endif
1740
1741 // Assumes classes in the SystemDictionary are only unloaded at a safepoint
1742 // Note: anonymous classes are not in the SD.
1743 bool SystemDictionary::do_unloading(BoolObjectClosure* is_alive,
1744 bool clean_previous_versions) {
1745 // First, mark for unload all ClassLoaderData referencing a dead class loader.
1746 bool unloading_occurred = ClassLoaderDataGraph::do_unloading(is_alive,
1747 clean_previous_versions);
1748 if (unloading_occurred) {
1749 dictionary()->do_unloading();
1750 constraints()->purge_loader_constraints();
1751 resolution_errors()->purge_resolution_errors();
1752 }
1753 // Oops referenced by the system dictionary may get unreachable independently
1754 // of the class loader (eg. cached protection domain oops). So we need to
1755 // explicitly unlink them here instead of in Dictionary::do_unloading.
1756 dictionary()->unlink(is_alive);
1757 #ifdef ASSERT
1758 VerifySDReachableAndLiveClosure cl(is_alive);
1759 dictionary()->oops_do(&cl);
1760 #endif
1761 return unloading_occurred;
1762 }
1763
1764 void SystemDictionary::roots_oops_do(OopClosure* strong, OopClosure* weak) {
1765 strong->do_oop(&_java_system_loader);
1766 strong->do_oop(&_system_loader_lock_obj);
1767 CDS_ONLY(SystemDictionaryShared::roots_oops_do(strong);)
1768
1769 // Adjust dictionary
1770 dictionary()->roots_oops_do(strong, weak);
1771
1772 // Visit extra methods
1773 invoke_method_table()->oops_do(strong);
1774 }
1775
1776 void SystemDictionary::oops_do(OopClosure* f) {
1777 f->do_oop(&_java_system_loader);
1778 f->do_oop(&_system_loader_lock_obj);
1779 CDS_ONLY(SystemDictionaryShared::oops_do(f);)
1780
1781 // Adjust dictionary
1782 dictionary()->oops_do(f);
1783
1784 // Visit extra methods
1785 invoke_method_table()->oops_do(f);
1786 }
1787
1788 // Extended Class redefinition support.
1789 // If one of these classes is replaced, we need to replace it in these places.
1790 // KlassClosure::do_klass should take the address of a class but we can
1791 // change that later.
1792 void SystemDictionary::preloaded_classes_do(KlassClosure* f) {
1793 for (int k = (int)FIRST_WKID; k < (int)WKID_LIMIT; k++) {
1794 f->do_klass(_well_known_klasses[k]);
1795 }
1796
1797 {
1798 for (int i = 0; i < T_VOID+1; i++) {
1799 if (_box_klasses[i] != NULL) {
1800 assert(i >= T_BOOLEAN, "checking");
1801 f->do_klass(_box_klasses[i]);
1802 }
1803 }
1804 }
1805
1806 FilteredFieldsMap::classes_do(f);
1807 }
1808
1809 void SystemDictionary::lazily_loaded_classes_do(KlassClosure* f) {
1810 f->do_klass(_abstract_ownable_synchronizer_klass);
1811 }
1812
1813 // Just the classes from defining class loaders
1814 // Don't iterate over placeholders
1815 void SystemDictionary::classes_do(void f(Klass*)) {
1816 dictionary()->classes_do(f);
1817 }
1818
1819 // Added for initialize_itable_for_klass
1820 // Just the classes from defining class loaders
1821 // Don't iterate over placeholders
1822 void SystemDictionary::classes_do(void f(Klass*, TRAPS), TRAPS) {
1823 dictionary()->classes_do(f, CHECK);
1824 }
1825
1826 // All classes, and their class loaders
1827 // Don't iterate over placeholders
1828 void SystemDictionary::classes_do(void f(Klass*, ClassLoaderData*)) {
1829 dictionary()->classes_do(f);
1830 }
1831
1832 void SystemDictionary::placeholders_do(void f(Symbol*)) {
1833 placeholders()->entries_do(f);
1834 }
1835
1836 void SystemDictionary::methods_do(void f(Method*)) {
1837 dictionary()->methods_do(f);
1838 invoke_method_table()->methods_do(f);
1839 }
1840
1841 void SystemDictionary::remove_classes_in_error_state() {
1842 dictionary()->remove_classes_in_error_state();
1843 }
1844
1845 // ----------------------------------------------------------------------------
1846 // Lazily load klasses
1847
1848 void SystemDictionary::load_abstract_ownable_synchronizer_klass(TRAPS) {
1849 // if multiple threads calling this function, only one thread will load
1850 // the class. The other threads will find the loaded version once the
1851 // class is loaded.
1852 Klass* aos = _abstract_ownable_synchronizer_klass;
1853 if (aos == NULL) {
1854 Klass* k = resolve_or_fail(vmSymbols::java_util_concurrent_locks_AbstractOwnableSynchronizer(), true, CHECK);
1855 // Force a fence to prevent any read before the write completes
1856 OrderAccess::fence();
1857 _abstract_ownable_synchronizer_klass = InstanceKlass::cast(k);
1858 }
1859 }
1860
1861 // ----------------------------------------------------------------------------
1862 // Initialization
1863
1864 void SystemDictionary::initialize(TRAPS) {
1865 // Allocate arrays
1866 assert(dictionary() == NULL,
1867 "SystemDictionary should only be initialized once");
1868 _sdgeneration = 0;
1869 _dictionary = new Dictionary(calculate_systemdictionary_size(PredictedLoadedClassCount));
1870 _placeholders = new PlaceholderTable(_nof_buckets);
1871 _number_of_modifications = 0;
1872 _loader_constraints = new LoaderConstraintTable(_loader_constraint_size);
1873 _resolution_errors = new ResolutionErrorTable(_resolution_error_size);
1874 _invoke_method_table = new SymbolPropertyTable(_invoke_method_size);
1875
1876 // Allocate private object used as system class loader lock
1877 _system_loader_lock_obj = oopFactory::new_intArray(0, CHECK);
1878 // Initialize basic classes
1879 initialize_preloaded_classes(CHECK);
1880 }
1881
1882 // Compact table of directions on the initialization of klasses:
1883 static const short wk_init_info[] = {
1884 #define WK_KLASS_INIT_INFO(name, symbol, option) \
1885 ( ((int)vmSymbols::VM_SYMBOL_ENUM_NAME(symbol) \
1886 << SystemDictionary::CEIL_LG_OPTION_LIMIT) \
1887 | (int)SystemDictionary::option ),
1888 WK_KLASSES_DO(WK_KLASS_INIT_INFO)
1889 #undef WK_KLASS_INIT_INFO
1890 0
1891 };
1892
1893 bool SystemDictionary::initialize_wk_klass(WKID id, int init_opt, TRAPS) {
1894 assert(id >= (int)FIRST_WKID && id < (int)WKID_LIMIT, "oob");
1895 int info = wk_init_info[id - FIRST_WKID];
1896 int sid = (info >> CEIL_LG_OPTION_LIMIT);
1897 Symbol* symbol = vmSymbols::symbol_at((vmSymbols::SID)sid);
1898 InstanceKlass** klassp = &_well_known_klasses[id];
1899 bool must_load = (init_opt < SystemDictionary::Opt);
1900 if ((*klassp) == NULL) {
1901 Klass* k;
1902 if (must_load) {
1903 k = resolve_or_fail(symbol, true, CHECK_0); // load required class
1904 } else {
1905 k = resolve_or_null(symbol, CHECK_0); // load optional klass
1906 }
1907 (*klassp) = (k == NULL) ? NULL : InstanceKlass::cast(k);
1908 }
1909 return ((*klassp) != NULL);
1910 }
1911
1912 void SystemDictionary::initialize_wk_klasses_until(WKID limit_id, WKID &start_id, TRAPS) {
1913 assert((int)start_id <= (int)limit_id, "IDs are out of order!");
1914 for (int id = (int)start_id; id < (int)limit_id; id++) {
1915 assert(id >= (int)FIRST_WKID && id < (int)WKID_LIMIT, "oob");
1916 int info = wk_init_info[id - FIRST_WKID];
1917 int sid = (info >> CEIL_LG_OPTION_LIMIT);
1918 int opt = (info & right_n_bits(CEIL_LG_OPTION_LIMIT));
1919
1920 initialize_wk_klass((WKID)id, opt, CHECK);
1921 }
1922
1923 // move the starting value forward to the limit:
1924 start_id = limit_id;
1925 }
1926
1927 void SystemDictionary::initialize_preloaded_classes(TRAPS) {
1928 assert(WK_KLASS(Object_klass) == NULL, "preloaded classes should only be initialized once");
1929 // Preload commonly used klasses
1930 WKID scan = FIRST_WKID;
1931 // first do Object, then String, Class
1932 if (UseSharedSpaces) {
1933 initialize_wk_klasses_through(WK_KLASS_ENUM_NAME(Object_klass), scan, CHECK);
1934 // Initialize the constant pool for the Object_class
1935 InstanceKlass* ik = InstanceKlass::cast(Object_klass());
1936 ik->constants()->restore_unshareable_info(CHECK);
1937 initialize_wk_klasses_through(WK_KLASS_ENUM_NAME(Class_klass), scan, CHECK);
1938 } else {
1939 initialize_wk_klasses_through(WK_KLASS_ENUM_NAME(Class_klass), scan, CHECK);
1940 }
1941
1942 // Calculate offsets for String and Class classes since they are loaded and
1943 // can be used after this point.
1944 java_lang_String::compute_offsets();
1945 java_lang_Class::compute_offsets();
1946
1947 // Fixup mirrors for classes loaded before java.lang.Class.
1948 // These calls iterate over the objects currently in the perm gen
1949 // so calling them at this point is matters (not before when there
1950 // are fewer objects and not later after there are more objects
1951 // in the perm gen.
1952 Universe::initialize_basic_type_mirrors(CHECK);
1953 Universe::fixup_mirrors(CHECK);
1954
1955 // do a bunch more:
1956 initialize_wk_klasses_through(WK_KLASS_ENUM_NAME(Reference_klass), scan, CHECK);
1957
1958 // Preload ref klasses and set reference types
1959 InstanceKlass::cast(WK_KLASS(Reference_klass))->set_reference_type(REF_OTHER);
1960 InstanceRefKlass::update_nonstatic_oop_maps(WK_KLASS(Reference_klass));
1961
1962 initialize_wk_klasses_through(WK_KLASS_ENUM_NAME(Cleaner_klass), scan, CHECK);
1963 InstanceKlass::cast(WK_KLASS(SoftReference_klass))->set_reference_type(REF_SOFT);
1964 InstanceKlass::cast(WK_KLASS(WeakReference_klass))->set_reference_type(REF_WEAK);
1965 InstanceKlass::cast(WK_KLASS(FinalReference_klass))->set_reference_type(REF_FINAL);
1966 InstanceKlass::cast(WK_KLASS(PhantomReference_klass))->set_reference_type(REF_PHANTOM);
1967 InstanceKlass::cast(WK_KLASS(Cleaner_klass))->set_reference_type(REF_CLEANER);
1968
1969 // JSR 292 classes
1970 WKID jsr292_group_start = WK_KLASS_ENUM_NAME(MethodHandle_klass);
1971 WKID jsr292_group_end = WK_KLASS_ENUM_NAME(VolatileCallSite_klass);
1972 initialize_wk_klasses_until(jsr292_group_start, scan, CHECK);
1973 initialize_wk_klasses_through(jsr292_group_end, scan, CHECK);
1974 initialize_wk_klasses_until(NOT_JVMCI(WKID_LIMIT) JVMCI_ONLY(FIRST_JVMCI_WKID), scan, CHECK);
1975
1976 _box_klasses[T_BOOLEAN] = WK_KLASS(Boolean_klass);
1977 _box_klasses[T_CHAR] = WK_KLASS(Character_klass);
1978 _box_klasses[T_FLOAT] = WK_KLASS(Float_klass);
1979 _box_klasses[T_DOUBLE] = WK_KLASS(Double_klass);
1980 _box_klasses[T_BYTE] = WK_KLASS(Byte_klass);
1981 _box_klasses[T_SHORT] = WK_KLASS(Short_klass);
1982 _box_klasses[T_INT] = WK_KLASS(Integer_klass);
1983 _box_klasses[T_LONG] = WK_KLASS(Long_klass);
1984 //_box_klasses[T_OBJECT] = WK_KLASS(object_klass);
1985 //_box_klasses[T_ARRAY] = WK_KLASS(object_klass);
1986
1987 { // Compute whether we should use loadClass or loadClassInternal when loading classes.
1988 Method* method = InstanceKlass::cast(ClassLoader_klass())->find_method(vmSymbols::loadClassInternal_name(), vmSymbols::string_class_signature());
1989 _has_loadClassInternal = (method != NULL);
1990 }
1991 { // Compute whether we should use checkPackageAccess or NOT
1992 Method* method = InstanceKlass::cast(ClassLoader_klass())->find_method(vmSymbols::checkPackageAccess_name(), vmSymbols::class_protectiondomain_signature());
1993 _has_checkPackageAccess = (method != NULL);
1994 }
1995 }
1996
1997 // Tells if a given klass is a box (wrapper class, such as java.lang.Integer).
1998 // If so, returns the basic type it holds. If not, returns T_OBJECT.
1999 BasicType SystemDictionary::box_klass_type(Klass* k) {
2000 assert(k != NULL, "");
2001 for (int i = T_BOOLEAN; i < T_VOID+1; i++) {
2002 if (_box_klasses[i] == k)
2003 return (BasicType)i;
2004 }
2005 return T_OBJECT;
2006 }
2007
2008 // Constraints on class loaders. The details of the algorithm can be
2009 // found in the OOPSLA'98 paper "Dynamic Class Loading in the Java
2010 // Virtual Machine" by Sheng Liang and Gilad Bracha. The basic idea is
2011 // that the system dictionary needs to maintain a set of contraints that
2012 // must be satisfied by all classes in the dictionary.
2013 // if defining is true, then LinkageError if already in systemDictionary
2014 // if initiating loader, then ok if InstanceKlass matches existing entry
2015
2016 void SystemDictionary::check_constraints(int d_index, unsigned int d_hash,
2017 instanceKlassHandle k,
2018 Handle class_loader, bool defining,
2019 TRAPS) {
2020 const char *linkage_error1 = NULL;
2021 const char *linkage_error2 = NULL;
2022 {
2023 Symbol* name = k->name();
2024 ClassLoaderData *loader_data = class_loader_data(class_loader);
2025
2026 MutexLocker mu(SystemDictionary_lock, THREAD);
2027
2028 Klass* check = find_class(d_index, d_hash, name, loader_data);
2029 if (check != (Klass*)NULL) {
2030 // if different InstanceKlass - duplicate class definition,
2031 // else - ok, class loaded by a different thread in parallel,
2032 // we should only have found it if it was done loading and ok to use
2033 // system dictionary only holds instance classes, placeholders
2034 // also holds array classes
2035
2036 assert(check->is_instance_klass(), "noninstance in systemdictionary");
2037 if ((defining == true) || (k() != check)) {
2038 linkage_error1 = "loader (instance of ";
2039 linkage_error2 = "): attempted duplicate class definition for name: \"";
2040 } else {
2041 return;
2042 }
2043 }
2044
2045 #ifdef ASSERT
2046 Symbol* ph_check = find_placeholder(name, loader_data);
2047 assert(ph_check == NULL || ph_check == name, "invalid symbol");
2048 #endif
2049
2050 if (linkage_error1 == NULL) {
2051 if (constraints()->check_or_update(k, class_loader, name) == false) {
2052 linkage_error1 = "loader constraint violation: loader (instance of ";
2053 linkage_error2 = ") previously initiated loading for a different type with name \"";
2054 }
2055 }
2056 }
2057
2058 // Throw error now if needed (cannot throw while holding
2059 // SystemDictionary_lock because of rank ordering)
2060
2061 if (linkage_error1) {
2062 ResourceMark rm(THREAD);
2063 const char* class_loader_name = loader_name(class_loader());
2064 char* type_name = k->name()->as_C_string();
2065 size_t buflen = strlen(linkage_error1) + strlen(class_loader_name) +
2066 strlen(linkage_error2) + strlen(type_name) + 2; // +2 for '"' and null byte.
2067 char* buf = NEW_RESOURCE_ARRAY_IN_THREAD(THREAD, char, buflen);
2068 jio_snprintf(buf, buflen, "%s%s%s%s\"", linkage_error1, class_loader_name, linkage_error2, type_name);
2069 THROW_MSG(vmSymbols::java_lang_LinkageError(), buf);
2070 }
2071 }
2072
2073
2074 // Update system dictionary - done after check_constraint and add_to_hierachy
2075 // have been called.
2076 void SystemDictionary::update_dictionary(int d_index, unsigned int d_hash,
2077 int p_index, unsigned int p_hash,
2078 instanceKlassHandle k,
2079 Handle class_loader,
2080 TRAPS) {
2081 // Compile_lock prevents systemDictionary updates during compilations
2082 assert_locked_or_safepoint(Compile_lock);
2083 Symbol* name = k->name();
2084 ClassLoaderData *loader_data = class_loader_data(class_loader);
2085
2086 {
2087 MutexLocker mu1(SystemDictionary_lock, THREAD);
2088
2089 // See whether biased locking is enabled and if so set it for this
2090 // klass.
2091 // Note that this must be done past the last potential blocking
2092 // point / safepoint. We enable biased locking lazily using a
2093 // VM_Operation to iterate the SystemDictionary and installing the
2094 // biasable mark word into each InstanceKlass's prototype header.
2095 // To avoid race conditions where we accidentally miss enabling the
2096 // optimization for one class in the process of being added to the
2097 // dictionary, we must not safepoint after the test of
2098 // BiasedLocking::enabled().
2099 if (UseBiasedLocking && BiasedLocking::enabled()) {
2100 // Set biased locking bit for all loaded classes; it will be
2101 // cleared if revocation occurs too often for this type
2102 // NOTE that we must only do this when the class is initally
2103 // defined, not each time it is referenced from a new class loader
2104 if (k->class_loader() == class_loader()) {
2105 k->set_prototype_header(markOopDesc::biased_locking_prototype());
2106 }
2107 }
2108
2109 // Make a new system dictionary entry.
2110 Klass* sd_check = find_class(d_index, d_hash, name, loader_data);
2111 if (sd_check == NULL) {
2112 dictionary()->add_klass(name, loader_data, k);
2113 notice_modification();
2114 }
2115 #ifdef ASSERT
2116 sd_check = find_class(d_index, d_hash, name, loader_data);
2117 assert (sd_check != NULL, "should have entry in system dictionary");
2118 // Note: there may be a placeholder entry: for circularity testing
2119 // or for parallel defines
2120 #endif
2121 SystemDictionary_lock->notify_all();
2122 }
2123 }
2124
2125
2126 // Try to find a class name using the loader constraints. The
2127 // loader constraints might know about a class that isn't fully loaded
2128 // yet and these will be ignored.
2129 Klass* SystemDictionary::find_constrained_instance_or_array_klass(
2130 Symbol* class_name, Handle class_loader, TRAPS) {
2131
2132 // First see if it has been loaded directly.
2133 // Force the protection domain to be null. (This removes protection checks.)
2134 Handle no_protection_domain;
2135 Klass* klass = find_instance_or_array_klass(class_name, class_loader,
2136 no_protection_domain, CHECK_NULL);
2137 if (klass != NULL)
2138 return klass;
2139
2140 // Now look to see if it has been loaded elsewhere, and is subject to
2141 // a loader constraint that would require this loader to return the
2142 // klass that is already loaded.
2143 if (FieldType::is_array(class_name)) {
2144 // For array classes, their Klass*s are not kept in the
2145 // constraint table. The element Klass*s are.
2146 FieldArrayInfo fd;
2147 BasicType t = FieldType::get_array_info(class_name, fd, CHECK_(NULL));
2148 if (t != T_OBJECT) {
2149 klass = Universe::typeArrayKlassObj(t);
2150 } else {
2151 MutexLocker mu(SystemDictionary_lock, THREAD);
2152 klass = constraints()->find_constrained_klass(fd.object_key(), class_loader);
2153 }
2154 // If element class already loaded, allocate array klass
2155 if (klass != NULL) {
2156 klass = klass->array_klass_or_null(fd.dimension());
2157 }
2158 } else {
2159 MutexLocker mu(SystemDictionary_lock, THREAD);
2160 // Non-array classes are easy: simply check the constraint table.
2161 klass = constraints()->find_constrained_klass(class_name, class_loader);
2162 }
2163
2164 return klass;
2165 }
2166
2167
2168 bool SystemDictionary::add_loader_constraint(Symbol* class_name,
2169 Handle class_loader1,
2170 Handle class_loader2,
2171 Thread* THREAD) {
2172 ClassLoaderData* loader_data1 = class_loader_data(class_loader1);
2173 ClassLoaderData* loader_data2 = class_loader_data(class_loader2);
2174
2175 Symbol* constraint_name = NULL;
2176 if (!FieldType::is_array(class_name)) {
2177 constraint_name = class_name;
2178 } else {
2179 // For array classes, their Klass*s are not kept in the
2180 // constraint table. The element classes are.
2181 FieldArrayInfo fd;
2182 BasicType t = FieldType::get_array_info(class_name, fd, CHECK_(false));
2183 // primitive types always pass
2184 if (t != T_OBJECT) {
2185 return true;
2186 } else {
2187 constraint_name = fd.object_key();
2188 }
2189 }
2190 unsigned int d_hash1 = dictionary()->compute_hash(constraint_name, loader_data1);
2191 int d_index1 = dictionary()->hash_to_index(d_hash1);
2192
2193 unsigned int d_hash2 = dictionary()->compute_hash(constraint_name, loader_data2);
2194 int d_index2 = dictionary()->hash_to_index(d_hash2);
2195 {
2196 MutexLocker mu_s(SystemDictionary_lock, THREAD);
2197
2198 // Better never do a GC while we're holding these oops
2199 No_Safepoint_Verifier nosafepoint;
2200
2201 Klass* klass1 = find_class(d_index1, d_hash1, constraint_name, loader_data1);
2202 Klass* klass2 = find_class(d_index2, d_hash2, constraint_name, loader_data2);
2203 return constraints()->add_entry(constraint_name, klass1, class_loader1,
2204 klass2, class_loader2);
2205 }
2206 }
2207
2208 // Add entry to resolution error table to record the error when the first
2209 // attempt to resolve a reference to a class has failed.
2210 void SystemDictionary::add_resolution_error(const constantPoolHandle& pool, int which,
2211 Symbol* error, Symbol* message) {
2212 unsigned int hash = resolution_errors()->compute_hash(pool, which);
2213 int index = resolution_errors()->hash_to_index(hash);
2214 {
2215 MutexLocker ml(SystemDictionary_lock, Thread::current());
2216 resolution_errors()->add_entry(index, hash, pool, which, error, message);
2217 }
2218 }
2219
2220 // Delete a resolution error for RedefineClasses for a constant pool is going away
2221 void SystemDictionary::delete_resolution_error(ConstantPool* pool) {
2222 resolution_errors()->delete_entry(pool);
2223 }
2224
2225 // Lookup resolution error table. Returns error if found, otherwise NULL.
2226 Symbol* SystemDictionary::find_resolution_error(const constantPoolHandle& pool, int which,
2227 Symbol** message) {
2228 unsigned int hash = resolution_errors()->compute_hash(pool, which);
2229 int index = resolution_errors()->hash_to_index(hash);
2230 {
2231 MutexLocker ml(SystemDictionary_lock, Thread::current());
2232 ResolutionErrorEntry* entry = resolution_errors()->find_entry(index, hash, pool, which);
2233 if (entry != NULL) {
2234 *message = entry->message();
2235 return entry->error();
2236 } else {
2237 return NULL;
2238 }
2239 }
2240 }
2241
2242
2243 // Signature constraints ensure that callers and callees agree about
2244 // the meaning of type names in their signatures. This routine is the
2245 // intake for constraints. It collects them from several places:
2246 //
2247 // * LinkResolver::resolve_method (if check_access is true) requires
2248 // that the resolving class (the caller) and the defining class of
2249 // the resolved method (the callee) agree on each type in the
2250 // method's signature.
2251 //
2252 // * LinkResolver::resolve_interface_method performs exactly the same
2253 // checks.
2254 //
2255 // * LinkResolver::resolve_field requires that the constant pool
2256 // attempting to link to a field agree with the field's defining
2257 // class about the type of the field signature.
2258 //
2259 // * klassVtable::initialize_vtable requires that, when a class
2260 // overrides a vtable entry allocated by a superclass, that the
2261 // overriding method (i.e., the callee) agree with the superclass
2262 // on each type in the method's signature.
2263 //
2264 // * klassItable::initialize_itable requires that, when a class fills
2265 // in its itables, for each non-abstract method installed in an
2266 // itable, the method (i.e., the callee) agree with the interface
2267 // on each type in the method's signature.
2268 //
2269 // All those methods have a boolean (check_access, checkconstraints)
2270 // which turns off the checks. This is used from specialized contexts
2271 // such as bootstrapping, dumping, and debugging.
2272 //
2273 // No direct constraint is placed between the class and its
2274 // supertypes. Constraints are only placed along linked relations
2275 // between callers and callees. When a method overrides or implements
2276 // an abstract method in a supertype (superclass or interface), the
2277 // constraints are placed as if the supertype were the caller to the
2278 // overriding method. (This works well, since callers to the
2279 // supertype have already established agreement between themselves and
2280 // the supertype.) As a result of all this, a class can disagree with
2281 // its supertype about the meaning of a type name, as long as that
2282 // class neither calls a relevant method of the supertype, nor is
2283 // called (perhaps via an override) from the supertype.
2284 //
2285 //
2286 // SystemDictionary::check_signature_loaders(sig, l1, l2)
2287 //
2288 // Make sure all class components (including arrays) in the given
2289 // signature will be resolved to the same class in both loaders.
2290 // Returns the name of the type that failed a loader constraint check, or
2291 // NULL if no constraint failed. No exception except OOME is thrown.
2292 // Arrays are not added to the loader constraint table, their elements are.
2293 Symbol* SystemDictionary::check_signature_loaders(Symbol* signature,
2294 Handle loader1, Handle loader2,
2295 bool is_method, TRAPS) {
2296 // Nothing to do if loaders are the same.
2297 if (loader1() == loader2()) {
2298 return NULL;
2299 }
2300
2301 SignatureStream sig_strm(signature, is_method);
2302 while (!sig_strm.is_done()) {
2303 if (sig_strm.is_object()) {
2304 Symbol* sig = sig_strm.as_symbol(CHECK_NULL);
2305 if (!add_loader_constraint(sig, loader1, loader2, THREAD)) {
2306 return sig;
2307 }
2308 }
2309 sig_strm.next();
2310 }
2311 return NULL;
2312 }
2313
2314
2315 methodHandle SystemDictionary::find_method_handle_intrinsic(vmIntrinsics::ID iid,
2316 Symbol* signature,
2317 TRAPS) {
2318 methodHandle empty;
2319 assert(MethodHandles::is_signature_polymorphic(iid) &&
2320 MethodHandles::is_signature_polymorphic_intrinsic(iid) &&
2321 iid != vmIntrinsics::_invokeGeneric,
2322 "must be a known MH intrinsic iid=%d: %s", iid, vmIntrinsics::name_at(iid));
2323
2324 unsigned int hash = invoke_method_table()->compute_hash(signature, iid);
2325 int index = invoke_method_table()->hash_to_index(hash);
2326 SymbolPropertyEntry* spe = invoke_method_table()->find_entry(index, hash, signature, iid);
2327 methodHandle m;
2328 if (spe == NULL || spe->method() == NULL) {
2329 spe = NULL;
2330 // Must create lots of stuff here, but outside of the SystemDictionary lock.
2331 m = Method::make_method_handle_intrinsic(iid, signature, CHECK_(empty));
2332 if (!Arguments::is_interpreter_only()) {
2333 // Generate a compiled form of the MH intrinsic.
2334 AdapterHandlerLibrary::create_native_wrapper(m);
2335 // Check if have the compiled code.
2336 if (!m->has_compiled_code()) {
2337 THROW_MSG_(vmSymbols::java_lang_VirtualMachineError(),
2338 "out of space in CodeCache for method handle intrinsic", empty);
2339 }
2340 }
2341 // Now grab the lock. We might have to throw away the new method,
2342 // if a racing thread has managed to install one at the same time.
2343 {
2344 MutexLocker ml(SystemDictionary_lock, THREAD);
2345 spe = invoke_method_table()->find_entry(index, hash, signature, iid);
2346 if (spe == NULL)
2347 spe = invoke_method_table()->add_entry(index, hash, signature, iid);
2348 if (spe->method() == NULL)
2349 spe->set_method(m());
2350 }
2351 }
2352
2353 assert(spe != NULL && spe->method() != NULL, "");
2354 assert(Arguments::is_interpreter_only() || (spe->method()->has_compiled_code() &&
2355 spe->method()->code()->entry_point() == spe->method()->from_compiled_entry()),
2356 "MH intrinsic invariant");
2357 return spe->method();
2358 }
2359
2360 // Helper for unpacking the return value from linkMethod and linkCallSite.
2361 static methodHandle unpack_method_and_appendix(Handle mname,
2362 KlassHandle accessing_klass,
2363 objArrayHandle appendix_box,
2364 Handle* appendix_result,
2365 TRAPS) {
2366 methodHandle empty;
2367 if (mname.not_null()) {
2368 Metadata* vmtarget = java_lang_invoke_MemberName::vmtarget(mname());
2369 if (vmtarget != NULL && vmtarget->is_method()) {
2370 Method* m = (Method*)vmtarget;
2371 oop appendix = appendix_box->obj_at(0);
2372 if (TraceMethodHandles) {
2373 #ifndef PRODUCT
2374 tty->print("Linked method=" INTPTR_FORMAT ": ", p2i(m));
2375 m->print();
2376 if (appendix != NULL) { tty->print("appendix = "); appendix->print(); }
2377 tty->cr();
2378 #endif //PRODUCT
2379 }
2380 (*appendix_result) = Handle(THREAD, appendix);
2381 // the target is stored in the cpCache and if a reference to this
2382 // MethodName is dropped we need a way to make sure the
2383 // class_loader containing this method is kept alive.
2384 // FIXME: the appendix might also preserve this dependency.
2385 ClassLoaderData* this_key = InstanceKlass::cast(accessing_klass())->class_loader_data();
2386 this_key->record_dependency(m->method_holder(), CHECK_NULL); // Can throw OOM
2387 return methodHandle(THREAD, m);
2388 }
2389 }
2390 THROW_MSG_(vmSymbols::java_lang_LinkageError(), "bad value from MethodHandleNatives", empty);
2391 return empty;
2392 }
2393
2394 methodHandle SystemDictionary::find_method_handle_invoker(Symbol* name,
2395 Symbol* signature,
2396 KlassHandle accessing_klass,
2397 Handle *appendix_result,
2398 Handle *method_type_result,
2399 TRAPS) {
2400 methodHandle empty;
2401 assert(THREAD->can_call_java() ,"");
2402 Handle method_type =
2403 SystemDictionary::find_method_handle_type(signature, accessing_klass, CHECK_(empty));
2404
2405 KlassHandle mh_klass = SystemDictionary::MethodHandle_klass();
2406 int ref_kind = JVM_REF_invokeVirtual;
2407 Handle name_str = StringTable::intern(name, CHECK_(empty));
2408 objArrayHandle appendix_box = oopFactory::new_objArray(SystemDictionary::Object_klass(), 1, CHECK_(empty));
2409 assert(appendix_box->obj_at(0) == NULL, "");
2410
2411 // This should not happen. JDK code should take care of that.
2412 if (accessing_klass.is_null() || method_type.is_null()) {
2413 THROW_MSG_(vmSymbols::java_lang_InternalError(), "bad invokehandle", empty);
2414 }
2415
2416 // call java.lang.invoke.MethodHandleNatives::linkMethod(... String, MethodType) -> MemberName
2417 JavaCallArguments args;
2418 args.push_oop(accessing_klass()->java_mirror());
2419 args.push_int(ref_kind);
2420 args.push_oop(mh_klass()->java_mirror());
2421 args.push_oop(name_str());
2422 args.push_oop(method_type());
2423 args.push_oop(appendix_box());
2424 JavaValue result(T_OBJECT);
2425 JavaCalls::call_static(&result,
2426 SystemDictionary::MethodHandleNatives_klass(),
2427 vmSymbols::linkMethod_name(),
2428 vmSymbols::linkMethod_signature(),
2429 &args, CHECK_(empty));
2430 Handle mname(THREAD, (oop) result.get_jobject());
2431 (*method_type_result) = method_type;
2432 return unpack_method_and_appendix(mname, accessing_klass, appendix_box, appendix_result, THREAD);
2433 }
2434
2435 // Decide if we can globally cache a lookup of this class, to be returned to any client that asks.
2436 // We must ensure that all class loaders everywhere will reach this class, for any client.
2437 // This is a safe bet for public classes in java.lang, such as Object and String.
2438 // We also include public classes in java.lang.invoke, because they appear frequently in system-level method types.
2439 // Out of an abundance of caution, we do not include any other classes, not even for packages like java.util.
2440 static bool is_always_visible_class(oop mirror) {
2441 Klass* klass = java_lang_Class::as_Klass(mirror);
2442 if (klass->is_objArray_klass()) {
2443 klass = ObjArrayKlass::cast(klass)->bottom_klass(); // check element type
2444 }
2445 if (klass->is_typeArray_klass()) {
2446 return true; // primitive array
2447 }
2448 assert(klass->is_instance_klass(), "%s", klass->external_name());
2449 return klass->is_public() &&
2450 (InstanceKlass::cast(klass)->is_same_class_package(SystemDictionary::Object_klass()) || // java.lang
2451 InstanceKlass::cast(klass)->is_same_class_package(SystemDictionary::MethodHandle_klass())); // java.lang.invoke
2452 }
2453
2454 // Ask Java code to find or construct a java.lang.invoke.MethodType for the given
2455 // signature, as interpreted relative to the given class loader.
2456 // Because of class loader constraints, all method handle usage must be
2457 // consistent with this loader.
2458 Handle SystemDictionary::find_method_handle_type(Symbol* signature,
2459 KlassHandle accessing_klass,
2460 TRAPS) {
2461 Handle empty;
2462 vmIntrinsics::ID null_iid = vmIntrinsics::_none; // distinct from all method handle invoker intrinsics
2463 unsigned int hash = invoke_method_table()->compute_hash(signature, null_iid);
2464 int index = invoke_method_table()->hash_to_index(hash);
2465 SymbolPropertyEntry* spe = invoke_method_table()->find_entry(index, hash, signature, null_iid);
2466 if (spe != NULL && spe->method_type() != NULL) {
2467 assert(java_lang_invoke_MethodType::is_instance(spe->method_type()), "");
2468 return Handle(THREAD, spe->method_type());
2469 } else if (!THREAD->can_call_java()) {
2470 warning("SystemDictionary::find_method_handle_type called from compiler thread"); // FIXME
2471 return Handle(); // do not attempt from within compiler, unless it was cached
2472 }
2473
2474 Handle class_loader, protection_domain;
2475 if (accessing_klass.not_null()) {
2476 class_loader = Handle(THREAD, InstanceKlass::cast(accessing_klass())->class_loader());
2477 protection_domain = Handle(THREAD, InstanceKlass::cast(accessing_klass())->protection_domain());
2478 }
2479 bool can_be_cached = true;
2480 int npts = ArgumentCount(signature).size();
2481 objArrayHandle pts = oopFactory::new_objArray(SystemDictionary::Class_klass(), npts, CHECK_(empty));
2482 int arg = 0;
2483 Handle rt; // the return type from the signature
2484 ResourceMark rm(THREAD);
2485 for (SignatureStream ss(signature); !ss.is_done(); ss.next()) {
2486 oop mirror = NULL;
2487 if (can_be_cached) {
2488 // Use neutral class loader to lookup candidate classes to be placed in the cache.
2489 mirror = ss.as_java_mirror(Handle(), Handle(),
2490 SignatureStream::ReturnNull, CHECK_(empty));
2491 if (mirror == NULL || (ss.is_object() && !is_always_visible_class(mirror))) {
2492 // Fall back to accessing_klass context.
2493 can_be_cached = false;
2494 }
2495 }
2496 if (!can_be_cached) {
2497 // Resolve, throwing a real error if it doesn't work.
2498 mirror = ss.as_java_mirror(class_loader, protection_domain,
2499 SignatureStream::NCDFError, CHECK_(empty));
2500 }
2501 assert(!oopDesc::is_null(mirror), "%s", ss.as_symbol(THREAD)->as_C_string());
2502 if (ss.at_return_type())
2503 rt = Handle(THREAD, mirror);
2504 else
2505 pts->obj_at_put(arg++, mirror);
2506
2507 // Check accessibility.
2508 if (ss.is_object() && accessing_klass.not_null()) {
2509 Klass* sel_klass = java_lang_Class::as_Klass(mirror);
2510 mirror = NULL; // safety
2511 // Emulate ConstantPool::verify_constant_pool_resolve.
2512 if (sel_klass->is_objArray_klass())
2513 sel_klass = ObjArrayKlass::cast(sel_klass)->bottom_klass();
2514 if (sel_klass->is_instance_klass()) {
2515 KlassHandle sel_kh(THREAD, sel_klass);
2516 LinkResolver::check_klass_accessability(accessing_klass, sel_kh, CHECK_(empty));
2517 }
2518 }
2519 }
2520 assert(arg == npts, "");
2521
2522 // call java.lang.invoke.MethodHandleNatives::findMethodType(Class rt, Class[] pts) -> MethodType
2523 JavaCallArguments args(Handle(THREAD, rt()));
2524 args.push_oop(pts());
2525 JavaValue result(T_OBJECT);
2526 JavaCalls::call_static(&result,
2527 SystemDictionary::MethodHandleNatives_klass(),
2528 vmSymbols::findMethodHandleType_name(),
2529 vmSymbols::findMethodHandleType_signature(),
2530 &args, CHECK_(empty));
2531 Handle method_type(THREAD, (oop) result.get_jobject());
2532
2533 if (can_be_cached) {
2534 // We can cache this MethodType inside the JVM.
2535 MutexLocker ml(SystemDictionary_lock, THREAD);
2536 spe = invoke_method_table()->find_entry(index, hash, signature, null_iid);
2537 if (spe == NULL)
2538 spe = invoke_method_table()->add_entry(index, hash, signature, null_iid);
2539 if (spe->method_type() == NULL) {
2540 spe->set_method_type(method_type());
2541 }
2542 }
2543
2544 // report back to the caller with the MethodType
2545 return method_type;
2546 }
2547
2548 // Ask Java code to find or construct a method handle constant.
2549 Handle SystemDictionary::link_method_handle_constant(KlassHandle caller,
2550 int ref_kind, //e.g., JVM_REF_invokeVirtual
2551 KlassHandle callee,
2552 Symbol* name_sym,
2553 Symbol* signature,
2554 TRAPS) {
2555 Handle empty;
2556 Handle name = java_lang_String::create_from_symbol(name_sym, CHECK_(empty));
2557 Handle type;
2558 if (signature->utf8_length() > 0 && signature->byte_at(0) == '(') {
2559 type = find_method_handle_type(signature, caller, CHECK_(empty));
2560 } else if (caller.is_null()) {
2561 // This should not happen. JDK code should take care of that.
2562 THROW_MSG_(vmSymbols::java_lang_InternalError(), "bad MH constant", empty);
2563 } else {
2564 ResourceMark rm(THREAD);
2565 SignatureStream ss(signature, false);
2566 if (!ss.is_done()) {
2567 oop mirror = ss.as_java_mirror(caller->class_loader(), caller->protection_domain(),
2568 SignatureStream::NCDFError, CHECK_(empty));
2569 type = Handle(THREAD, mirror);
2570 ss.next();
2571 if (!ss.is_done()) type = Handle(); // error!
2572 }
2573 }
2574 if (type.is_null()) {
2575 THROW_MSG_(vmSymbols::java_lang_LinkageError(), "bad signature", empty);
2576 }
2577
2578 // call java.lang.invoke.MethodHandleNatives::linkMethodHandleConstant(Class caller, int refKind, Class callee, String name, Object type) -> MethodHandle
2579 JavaCallArguments args;
2580 args.push_oop(caller->java_mirror()); // the referring class
2581 args.push_int(ref_kind);
2582 args.push_oop(callee->java_mirror()); // the target class
2583 args.push_oop(name());
2584 args.push_oop(type());
2585 JavaValue result(T_OBJECT);
2586 JavaCalls::call_static(&result,
2587 SystemDictionary::MethodHandleNatives_klass(),
2588 vmSymbols::linkMethodHandleConstant_name(),
2589 vmSymbols::linkMethodHandleConstant_signature(),
2590 &args, CHECK_(empty));
2591 return Handle(THREAD, (oop) result.get_jobject());
2592 }
2593
2594 // Ask Java code to find or construct a java.lang.invoke.CallSite for the given
2595 // name and signature, as interpreted relative to the given class loader.
2596 methodHandle SystemDictionary::find_dynamic_call_site_invoker(KlassHandle caller,
2597 Handle bootstrap_specifier,
2598 Symbol* name,
2599 Symbol* type,
2600 Handle *appendix_result,
2601 Handle *method_type_result,
2602 TRAPS) {
2603 methodHandle empty;
2604 Handle bsm, info;
2605 if (java_lang_invoke_MethodHandle::is_instance(bootstrap_specifier())) {
2606 bsm = bootstrap_specifier;
2607 } else {
2608 assert(bootstrap_specifier->is_objArray(), "");
2609 objArrayHandle args(THREAD, (objArrayOop) bootstrap_specifier());
2610 int len = args->length();
2611 assert(len >= 1, "");
2612 bsm = Handle(THREAD, args->obj_at(0));
2613 if (len > 1) {
2614 objArrayOop args1 = oopFactory::new_objArray(SystemDictionary::Object_klass(), len-1, CHECK_(empty));
2615 for (int i = 1; i < len; i++)
2616 args1->obj_at_put(i-1, args->obj_at(i));
2617 info = Handle(THREAD, args1);
2618 }
2619 }
2620 guarantee(java_lang_invoke_MethodHandle::is_instance(bsm()),
2621 "caller must supply a valid BSM");
2622
2623 Handle method_name = java_lang_String::create_from_symbol(name, CHECK_(empty));
2624 Handle method_type = find_method_handle_type(type, caller, CHECK_(empty));
2625
2626 // This should not happen. JDK code should take care of that.
2627 if (caller.is_null() || method_type.is_null()) {
2628 THROW_MSG_(vmSymbols::java_lang_InternalError(), "bad invokedynamic", empty);
2629 }
2630
2631 objArrayHandle appendix_box = oopFactory::new_objArray(SystemDictionary::Object_klass(), 1, CHECK_(empty));
2632 assert(appendix_box->obj_at(0) == NULL, "");
2633
2634 // call java.lang.invoke.MethodHandleNatives::linkCallSite(caller, bsm, name, mtype, info, &appendix)
2635 JavaCallArguments args;
2636 args.push_oop(caller->java_mirror());
2637 args.push_oop(bsm());
2638 args.push_oop(method_name());
2639 args.push_oop(method_type());
2640 args.push_oop(info());
2641 args.push_oop(appendix_box);
2642 JavaValue result(T_OBJECT);
2643 JavaCalls::call_static(&result,
2644 SystemDictionary::MethodHandleNatives_klass(),
2645 vmSymbols::linkCallSite_name(),
2646 vmSymbols::linkCallSite_signature(),
2647 &args, CHECK_(empty));
2648 Handle mname(THREAD, (oop) result.get_jobject());
2649 (*method_type_result) = method_type;
2650 return unpack_method_and_appendix(mname, caller, appendix_box, appendix_result, THREAD);
2651 }
2652
2653 // Since the identity hash code for symbols changes when the symbols are
2654 // moved from the regular perm gen (hash in the mark word) to the shared
2655 // spaces (hash is the address), the classes loaded into the dictionary
2656 // may be in the wrong buckets.
2657
2658 void SystemDictionary::reorder_dictionary() {
2659 dictionary()->reorder_dictionary();
2660 }
2661
2662
2663 void SystemDictionary::copy_buckets(char** top, char* end) {
2664 dictionary()->copy_buckets(top, end);
2665 }
2666
2667
2668 void SystemDictionary::copy_table(char** top, char* end) {
2669 dictionary()->copy_table(top, end);
2670 }
2671
2672
2673 void SystemDictionary::reverse() {
2674 dictionary()->reverse();
2675 }
2676
2677 int SystemDictionary::number_of_classes() {
2678 return dictionary()->number_of_entries();
2679 }
2680
2681
2682 // ----------------------------------------------------------------------------
2683 void SystemDictionary::print_shared(bool details) {
2684 shared_dictionary()->print(details);
2685 }
2686
2687 void SystemDictionary::print(bool details) {
2688 dictionary()->print(details);
2689
2690 // Placeholders
2691 GCMutexLocker mu(SystemDictionary_lock);
2692 placeholders()->print();
2693
2694 // loader constraints - print under SD_lock
2695 constraints()->print();
2696 }
2697
2698
2699 void SystemDictionary::verify() {
2700 guarantee(dictionary() != NULL, "Verify of system dictionary failed");
2701 guarantee(constraints() != NULL,
2702 "Verify of loader constraints failed");
2703 guarantee(dictionary()->number_of_entries() >= 0 &&
2704 placeholders()->number_of_entries() >= 0,
2705 "Verify of system dictionary failed");
2706
2707 // Verify dictionary
2708 dictionary()->verify();
2709
2710 GCMutexLocker mu(SystemDictionary_lock);
2711 placeholders()->verify();
2712
2713 // Verify constraint table
2714 guarantee(constraints() != NULL, "Verify of loader constraints failed");
2715 constraints()->verify(dictionary(), placeholders());
2716 }
2717
2718 // utility function for class load event
2719 void SystemDictionary::post_class_load_event(const Ticks& start_time,
2720 instanceKlassHandle k,
2721 Handle initiating_loader) {
2722 #if INCLUDE_TRACE
2723 EventClassLoad event(UNTIMED);
2724 if (event.should_commit()) {
2725 event.set_starttime(start_time);
2726 event.set_loadedClass(k());
2727 oop defining_class_loader = k->class_loader();
2728 event.set_definingClassLoader(defining_class_loader != NULL ?
2729 defining_class_loader->klass() : (Klass*)NULL);
2730 oop class_loader = initiating_loader.is_null() ? (oop)NULL : initiating_loader();
2731 event.set_initiatingClassLoader(class_loader != NULL ?
2732 class_loader->klass() : (Klass*)NULL);
2733 event.commit();
2734 }
2735 #endif // INCLUDE_TRACE
2736 }
2737