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 "logging/log.hpp"
41 #include "memory/filemap.hpp"
42 #include "memory/oopFactory.hpp"
43 #include "oops/instanceKlass.hpp"
44 #include "oops/instanceRefKlass.hpp"
45 #include "oops/klass.inline.hpp"
46 #include "oops/methodData.hpp"
47 #include "oops/objArrayKlass.hpp"
48 #include "oops/objArrayOop.inline.hpp"
49 #include "oops/oop.inline.hpp"
50 #include "oops/typeArrayKlass.hpp"
51 #include "prims/jvmtiEnvBase.hpp"
52 #include "prims/methodHandles.hpp"
53 #include "runtime/arguments.hpp"
54 #include "runtime/biasedLocking.hpp"
55 #include "runtime/fieldType.hpp"
56 #include "runtime/handles.inline.hpp"
57 #include "runtime/java.hpp"
58 #include "runtime/javaCalls.hpp"
59 #include "runtime/mutexLocker.hpp"
60 #include "runtime/orderAccess.inline.hpp"
61 #include "runtime/signature.hpp"
62 #include "services/classLoadingService.hpp"
63 #include "services/threadService.hpp"
64 #include "utilities/macros.hpp"
65 #include "utilities/ticks.hpp"
66 #if INCLUDE_CDS
67 #include "classfile/sharedClassUtil.hpp"
68 #include "classfile/systemDictionaryShared.hpp"
69 #endif
70 #if INCLUDE_JVMCI
71 #include "jvmci/jvmciRuntime.hpp"
72 #endif
73 #if INCLUDE_TRACE
74 #include "trace/tracing.hpp"
75 #endif
76
77 Dictionary* SystemDictionary::_dictionary = NULL;
78 PlaceholderTable* SystemDictionary::_placeholders = NULL;
79 Dictionary* SystemDictionary::_shared_dictionary = NULL;
80 LoaderConstraintTable* SystemDictionary::_loader_constraints = NULL;
81 ResolutionErrorTable* SystemDictionary::_resolution_errors = NULL;
82 SymbolPropertyTable* SystemDictionary::_invoke_method_table = NULL;
83
84
85 int SystemDictionary::_number_of_modifications = 0;
86 int SystemDictionary::_sdgeneration = 0;
87 const int SystemDictionary::_primelist[_prime_array_size] = {1009,2017,4049,5051,10103,
88 20201,40423,99991};
89
90 oop SystemDictionary::_system_loader_lock_obj = NULL;
91
92 InstanceKlass* SystemDictionary::_well_known_klasses[SystemDictionary::WKID_LIMIT]
93 = { NULL /*, NULL...*/ };
94
95 InstanceKlass* SystemDictionary::_box_klasses[T_VOID+1] = { NULL /*, NULL...*/ };
96
97 oop SystemDictionary::_java_system_loader = NULL;
98
99 bool SystemDictionary::_has_loadClassInternal = false;
100 bool SystemDictionary::_has_checkPackageAccess = false;
101
102 // lazily initialized klass variables
103 InstanceKlass* volatile SystemDictionary::_abstract_ownable_synchronizer_klass = NULL;
104
105
106 // ----------------------------------------------------------------------------
107 // Java-level SystemLoader
108
109 oop SystemDictionary::java_system_loader() {
110 return _java_system_loader;
111 }
112
113 void SystemDictionary::compute_java_system_loader(TRAPS) {
114 KlassHandle system_klass(THREAD, WK_KLASS(ClassLoader_klass));
115 JavaValue result(T_OBJECT);
116 JavaCalls::call_static(&result,
117 KlassHandle(THREAD, WK_KLASS(ClassLoader_klass)),
118 vmSymbols::getSystemClassLoader_name(),
119 vmSymbols::void_classloader_signature(),
120 CHECK);
121
122 _java_system_loader = (oop)result.get_jobject();
123
124 CDS_ONLY(SystemDictionaryShared::initialize(CHECK);)
125 }
126
127
128 ClassLoaderData* SystemDictionary::register_loader(Handle class_loader, TRAPS) {
129 if (class_loader() == NULL) return ClassLoaderData::the_null_class_loader_data();
130 return ClassLoaderDataGraph::find_or_create(class_loader, THREAD);
131 }
132
133 // ----------------------------------------------------------------------------
134 // debugging
135
136 #ifdef ASSERT
137
138 // return true if class_name contains no '.' (internal format is '/')
139 bool SystemDictionary::is_internal_format(Symbol* class_name) {
140 if (class_name != NULL) {
141 ResourceMark rm;
142 char* name = class_name->as_C_string();
143 return strchr(name, '.') == NULL;
144 } else {
145 return true;
146 }
147 }
148
149 #endif
150
151 // ----------------------------------------------------------------------------
152 // Parallel class loading check
153
154 bool SystemDictionary::is_parallelCapable(Handle class_loader) {
155 if (UnsyncloadClass || class_loader.is_null()) return true;
156 if (AlwaysLockClassLoader) return false;
157 return java_lang_ClassLoader::parallelCapable(class_loader());
158 }
159 // ----------------------------------------------------------------------------
160 // ParallelDefineClass flag does not apply to bootclass loader
161 bool SystemDictionary::is_parallelDefine(Handle class_loader) {
162 if (class_loader.is_null()) return false;
163 if (AllowParallelDefineClass && java_lang_ClassLoader::parallelCapable(class_loader())) {
164 return true;
165 }
166 return false;
167 }
168
169 /**
170 * Returns true if the passed class loader is the extension class loader.
171 */
172 bool SystemDictionary::is_ext_class_loader(Handle class_loader) {
173 if (class_loader.is_null()) {
174 return false;
175 }
176 return (class_loader->klass()->name() == vmSymbols::sun_misc_Launcher_ExtClassLoader());
177 }
178
179 // ----------------------------------------------------------------------------
180 // Resolving of classes
181
182 // Forwards to resolve_or_null
183
184 Klass* SystemDictionary::resolve_or_fail(Symbol* class_name, Handle class_loader, Handle protection_domain, bool throw_error, TRAPS) {
185 Klass* klass = resolve_or_null(class_name, class_loader, protection_domain, THREAD);
186 if (HAS_PENDING_EXCEPTION || klass == NULL) {
187 KlassHandle k_h(THREAD, klass);
188 // can return a null klass
189 klass = handle_resolution_exception(class_name, throw_error, k_h, THREAD);
190 }
191 return klass;
192 }
193
194 Klass* SystemDictionary::handle_resolution_exception(Symbol* class_name,
195 bool throw_error,
196 KlassHandle klass_h, TRAPS) {
197 if (HAS_PENDING_EXCEPTION) {
198 // If we have a pending exception we forward it to the caller, unless throw_error is true,
199 // in which case we have to check whether the pending exception is a ClassNotFoundException,
200 // and if so convert it to a NoClassDefFoundError
201 // And chain the original ClassNotFoundException
202 if (throw_error && PENDING_EXCEPTION->is_a(SystemDictionary::ClassNotFoundException_klass())) {
203 ResourceMark rm(THREAD);
204 assert(klass_h() == NULL, "Should not have result with exception pending");
205 Handle e(THREAD, PENDING_EXCEPTION);
206 CLEAR_PENDING_EXCEPTION;
207 THROW_MSG_CAUSE_NULL(vmSymbols::java_lang_NoClassDefFoundError(), class_name->as_C_string(), e);
208 } else {
209 return NULL;
210 }
211 }
212 // Class not found, throw appropriate error or exception depending on value of throw_error
213 if (klass_h() == NULL) {
214 ResourceMark rm(THREAD);
215 if (throw_error) {
216 THROW_MSG_NULL(vmSymbols::java_lang_NoClassDefFoundError(), class_name->as_C_string());
217 } else {
218 THROW_MSG_NULL(vmSymbols::java_lang_ClassNotFoundException(), class_name->as_C_string());
219 }
220 }
221 return (Klass*)klass_h();
222 }
223
224
225 Klass* SystemDictionary::resolve_or_fail(Symbol* class_name,
226 bool throw_error, TRAPS)
227 {
228 return resolve_or_fail(class_name, Handle(), Handle(), throw_error, THREAD);
229 }
230
231
232 // Forwards to resolve_instance_class_or_null
233
234 Klass* SystemDictionary::resolve_or_null(Symbol* class_name, Handle class_loader, Handle protection_domain, TRAPS) {
235 assert(THREAD->can_call_java(),
236 "can not load classes with compiler thread: class=%s, classloader=%s",
237 class_name->as_C_string(),
238 class_loader.is_null() ? "null" : class_loader->klass()->name()->as_C_string());
239 if (FieldType::is_array(class_name)) {
240 return resolve_array_class_or_null(class_name, class_loader, protection_domain, THREAD);
241 } else if (FieldType::is_obj(class_name)) {
242 ResourceMark rm(THREAD);
243 // Ignore wrapping L and ;.
244 TempNewSymbol name = SymbolTable::new_symbol(class_name->as_C_string() + 1,
245 class_name->utf8_length() - 2, CHECK_NULL);
246 return resolve_instance_class_or_null(name, class_loader, protection_domain, THREAD);
247 } else {
248 return resolve_instance_class_or_null(class_name, class_loader, protection_domain, THREAD);
249 }
250 }
251
252 Klass* SystemDictionary::resolve_or_null(Symbol* class_name, TRAPS) {
253 return resolve_or_null(class_name, Handle(), Handle(), THREAD);
254 }
255
256 // Forwards to resolve_instance_class_or_null
257
258 Klass* SystemDictionary::resolve_array_class_or_null(Symbol* class_name,
259 Handle class_loader,
260 Handle protection_domain,
261 TRAPS) {
262 assert(FieldType::is_array(class_name), "must be array");
263 Klass* k = NULL;
264 FieldArrayInfo fd;
265 // dimension and object_key in FieldArrayInfo are assigned as a side-effect
266 // of this call
267 BasicType t = FieldType::get_array_info(class_name, fd, CHECK_NULL);
268 if (t == T_OBJECT) {
269 // naked oop "k" is OK here -- we assign back into it
270 k = SystemDictionary::resolve_instance_class_or_null(fd.object_key(),
271 class_loader,
272 protection_domain,
273 CHECK_NULL);
274 if (k != NULL) {
275 k = k->array_klass(fd.dimension(), CHECK_NULL);
276 }
277 } else {
278 k = Universe::typeArrayKlassObj(t);
279 k = TypeArrayKlass::cast(k)->array_klass(fd.dimension(), CHECK_NULL);
280 }
281 return k;
282 }
283
284
285 // Must be called for any super-class or super-interface resolution
286 // during class definition to allow class circularity checking
287 // super-interface callers:
288 // parse_interfaces - for defineClass & jvmtiRedefineClasses
289 // super-class callers:
290 // ClassFileParser - for defineClass & jvmtiRedefineClasses
291 // load_shared_class - while loading a class from shared archive
292 // resolve_instance_class_or_null:
293 // via: handle_parallel_super_load
294 // when resolving a class that has an existing placeholder with
295 // a saved superclass [i.e. a defineClass is currently in progress]
296 // if another thread is trying to resolve the class, it must do
297 // super-class checks on its own thread to catch class circularity
298 // This last call is critical in class circularity checking for cases
299 // where classloading is delegated to different threads and the
300 // classloader lock is released.
301 // Take the case: Base->Super->Base
302 // 1. If thread T1 tries to do a defineClass of class Base
303 // resolve_super_or_fail creates placeholder: T1, Base (super Super)
304 // 2. resolve_instance_class_or_null does not find SD or placeholder for Super
305 // so it tries to load Super
306 // 3. If we load the class internally, or user classloader uses same thread
307 // loadClassFromxxx or defineClass via parseClassFile Super ...
308 // 3.1 resolve_super_or_fail creates placeholder: T1, Super (super Base)
309 // 3.3 resolve_instance_class_or_null Base, finds placeholder for Base
310 // 3.4 calls resolve_super_or_fail Base
311 // 3.5 finds T1,Base -> throws class circularity
312 //OR 4. If T2 tries to resolve Super via defineClass Super ...
313 // 4.1 resolve_super_or_fail creates placeholder: T2, Super (super Base)
314 // 4.2 resolve_instance_class_or_null Base, finds placeholder for Base (super Super)
315 // 4.3 calls resolve_super_or_fail Super in parallel on own thread T2
316 // 4.4 finds T2, Super -> throws class circularity
317 // Must be called, even if superclass is null, since this is
318 // where the placeholder entry is created which claims this
319 // thread is loading this class/classloader.
320 Klass* SystemDictionary::resolve_super_or_fail(Symbol* child_name,
321 Symbol* class_name,
322 Handle class_loader,
323 Handle protection_domain,
324 bool is_superclass,
325 TRAPS) {
326 #if INCLUDE_CDS
327 if (DumpSharedSpaces) {
328 // Special processing for CDS dump time.
329 Klass* k = SystemDictionaryShared::dump_time_resolve_super_or_fail(child_name,
330 class_name, class_loader, protection_domain, is_superclass, CHECK_NULL);
331 if (k) {
332 return k;
333 }
334 }
335 #endif // INCLUDE_CDS
336
337 // Double-check, if child class is already loaded, just return super-class,interface
338 // Don't add a placedholder if already loaded, i.e. already in system dictionary
339 // Make sure there's a placeholder for the *child* before resolving.
340 // Used as a claim that this thread is currently loading superclass/classloader
341 // Used here for ClassCircularity checks and also for heap verification
342 // (every InstanceKlass in the heap needs to be in the system dictionary
343 // or have a placeholder).
344 // Must check ClassCircularity before checking if super class is already loaded
345 //
346 // We might not already have a placeholder if this child_name was
347 // first seen via resolve_from_stream (jni_DefineClass or JVM_DefineClass);
348 // the name of the class might not be known until the stream is actually
349 // parsed.
350 // Bugs 4643874, 4715493
351 // compute_hash can have a safepoint
352
353 ClassLoaderData* loader_data = class_loader_data(class_loader);
354 unsigned int d_hash = dictionary()->compute_hash(child_name, loader_data);
355 int d_index = dictionary()->hash_to_index(d_hash);
356 unsigned int p_hash = placeholders()->compute_hash(child_name, loader_data);
357 int p_index = placeholders()->hash_to_index(p_hash);
358 // can't throw error holding a lock
359 bool child_already_loaded = false;
360 bool throw_circularity_error = false;
361 {
362 MutexLocker mu(SystemDictionary_lock, THREAD);
363 Klass* childk = find_class(d_index, d_hash, child_name, loader_data);
364 Klass* quicksuperk;
365 // to support // loading: if child done loading, just return superclass
366 // if class_name, & class_loader don't match:
367 // if initial define, SD update will give LinkageError
368 // if redefine: compare_class_versions will give HIERARCHY_CHANGED
369 // so we don't throw an exception here.
370 // see: nsk redefclass014 & java.lang.instrument Instrument032
371 if ((childk != NULL ) && (is_superclass) &&
372 ((quicksuperk = childk->super()) != NULL) &&
373
374 ((quicksuperk->name() == class_name) &&
375 (quicksuperk->class_loader() == class_loader()))) {
376 return quicksuperk;
377 } else {
378 PlaceholderEntry* probe = placeholders()->get_entry(p_index, p_hash, child_name, loader_data);
379 if (probe && probe->check_seen_thread(THREAD, PlaceholderTable::LOAD_SUPER)) {
380 throw_circularity_error = true;
381 }
382 }
383 if (!throw_circularity_error) {
384 PlaceholderEntry* newprobe = placeholders()->find_and_add(p_index, p_hash, child_name, loader_data, PlaceholderTable::LOAD_SUPER, class_name, THREAD);
385 }
386 }
387 if (throw_circularity_error) {
388 ResourceMark rm(THREAD);
389 THROW_MSG_NULL(vmSymbols::java_lang_ClassCircularityError(), child_name->as_C_string());
390 }
391
392 // java.lang.Object should have been found above
393 assert(class_name != NULL, "null super class for resolving");
394 // Resolve the super class or interface, check results on return
395 Klass* superk = SystemDictionary::resolve_or_null(class_name,
396 class_loader,
397 protection_domain,
398 THREAD);
399
400 KlassHandle superk_h(THREAD, superk);
401
402 // Clean up of placeholders moved so that each classloadAction registrar self-cleans up
403 // It is no longer necessary to keep the placeholder table alive until update_dictionary
404 // or error. GC used to walk the placeholder table as strong roots.
405 // The instanceKlass is kept alive because the class loader is on the stack,
406 // which keeps the loader_data alive, as well as all instanceKlasses in
407 // the loader_data. parseClassFile adds the instanceKlass to loader_data.
408 {
409 MutexLocker mu(SystemDictionary_lock, THREAD);
410 placeholders()->find_and_remove(p_index, p_hash, child_name, loader_data, PlaceholderTable::LOAD_SUPER, THREAD);
411 SystemDictionary_lock->notify_all();
412 }
413 if (HAS_PENDING_EXCEPTION || superk_h() == NULL) {
414 // can null superk
415 superk_h = KlassHandle(THREAD, handle_resolution_exception(class_name, true, superk_h, THREAD));
416 }
417
418 return superk_h();
419 }
420
421 void SystemDictionary::validate_protection_domain(instanceKlassHandle klass,
422 Handle class_loader,
423 Handle protection_domain,
424 TRAPS) {
425 if(!has_checkPackageAccess()) return;
426
427 // Now we have to call back to java to check if the initating class has access
428 JavaValue result(T_VOID);
429 if (TraceProtectionDomainVerification) {
430 // Print out trace information
431 tty->print_cr("Checking package access");
432 tty->print(" - class loader: "); class_loader()->print_value_on(tty); tty->cr();
433 tty->print(" - protection domain: "); protection_domain()->print_value_on(tty); tty->cr();
434 tty->print(" - loading: "); klass()->print_value_on(tty); tty->cr();
435 }
436
437 KlassHandle system_loader(THREAD, SystemDictionary::ClassLoader_klass());
438 JavaCalls::call_special(&result,
439 class_loader,
440 system_loader,
441 vmSymbols::checkPackageAccess_name(),
442 vmSymbols::class_protectiondomain_signature(),
443 Handle(THREAD, klass->java_mirror()),
444 protection_domain,
445 THREAD);
446
447 if (TraceProtectionDomainVerification) {
448 if (HAS_PENDING_EXCEPTION) {
449 tty->print_cr(" -> DENIED !!!!!!!!!!!!!!!!!!!!!");
450 } else {
451 tty->print_cr(" -> granted");
452 }
453 tty->cr();
454 }
455
456 if (HAS_PENDING_EXCEPTION) return;
457
458 // If no exception has been thrown, we have validated the protection domain
459 // Insert the protection domain of the initiating class into the set.
460 {
461 // We recalculate the entry here -- we've called out to java since
462 // the last time it was calculated.
463 ClassLoaderData* loader_data = class_loader_data(class_loader);
464
465 Symbol* kn = klass->name();
466 unsigned int d_hash = dictionary()->compute_hash(kn, loader_data);
467 int d_index = dictionary()->hash_to_index(d_hash);
468
469 MutexLocker mu(SystemDictionary_lock, THREAD);
470 {
471 // Note that we have an entry, and entries can be deleted only during GC,
472 // so we cannot allow GC to occur while we're holding this entry.
473
474 // We're using a No_Safepoint_Verifier to catch any place where we
475 // might potentially do a GC at all.
476 // Dictionary::do_unloading() asserts that classes in SD are only
477 // unloaded at a safepoint. Anonymous classes are not in SD.
478 No_Safepoint_Verifier nosafepoint;
479 dictionary()->add_protection_domain(d_index, d_hash, klass, loader_data,
480 protection_domain, THREAD);
481 }
482 }
483 }
484
485 // We only get here if this thread finds that another thread
486 // has already claimed the placeholder token for the current operation,
487 // but that other thread either never owned or gave up the
488 // object lock
489 // Waits on SystemDictionary_lock to indicate placeholder table updated
490 // On return, caller must recheck placeholder table state
491 //
492 // We only get here if
493 // 1) custom classLoader, i.e. not bootstrap classloader
494 // 2) UnsyncloadClass not set
495 // 3) custom classLoader has broken the class loader objectLock
496 // so another thread got here in parallel
497 //
498 // lockObject must be held.
499 // Complicated dance due to lock ordering:
500 // Must first release the classloader object lock to
501 // allow initial definer to complete the class definition
502 // and to avoid deadlock
503 // Reclaim classloader lock object with same original recursion count
504 // Must release SystemDictionary_lock after notify, since
505 // class loader lock must be claimed before SystemDictionary_lock
506 // to prevent deadlocks
507 //
508 // The notify allows applications that did an untimed wait() on
509 // the classloader object lock to not hang.
510 void SystemDictionary::double_lock_wait(Handle lockObject, TRAPS) {
511 assert_lock_strong(SystemDictionary_lock);
512
513 bool calledholdinglock
514 = ObjectSynchronizer::current_thread_holds_lock((JavaThread*)THREAD, lockObject);
515 assert(calledholdinglock,"must hold lock for notify");
516 assert((!(lockObject() == _system_loader_lock_obj) && !is_parallelCapable(lockObject)), "unexpected double_lock_wait");
517 ObjectSynchronizer::notifyall(lockObject, THREAD);
518 intptr_t recursions = ObjectSynchronizer::complete_exit(lockObject, THREAD);
519 SystemDictionary_lock->wait();
520 SystemDictionary_lock->unlock();
521 ObjectSynchronizer::reenter(lockObject, recursions, THREAD);
522 SystemDictionary_lock->lock();
523 }
524
525 // If the class in is in the placeholder table, class loading is in progress
526 // For cases where the application changes threads to load classes, it
527 // is critical to ClassCircularity detection that we try loading
528 // the superclass on the same thread internally, so we do parallel
529 // super class loading here.
530 // This also is critical in cases where the original thread gets stalled
531 // even in non-circularity situations.
532 // Note: must call resolve_super_or_fail even if null super -
533 // to force placeholder entry creation for this class for circularity detection
534 // Caller must check for pending exception
535 // Returns non-null Klass* if other thread has completed load
536 // and we are done,
537 // If return null Klass* and no pending exception, the caller must load the class
538 instanceKlassHandle SystemDictionary::handle_parallel_super_load(
539 Symbol* name, Symbol* superclassname, Handle class_loader,
540 Handle protection_domain, Handle lockObject, TRAPS) {
541
542 instanceKlassHandle nh = instanceKlassHandle(); // null Handle
543 ClassLoaderData* loader_data = class_loader_data(class_loader);
544 unsigned int d_hash = dictionary()->compute_hash(name, loader_data);
545 int d_index = dictionary()->hash_to_index(d_hash);
546 unsigned int p_hash = placeholders()->compute_hash(name, loader_data);
547 int p_index = placeholders()->hash_to_index(p_hash);
548
549 // superk is not used, resolve_super called for circularity check only
550 // This code is reached in two situations. One if this thread
551 // is loading the same class twice (e.g. ClassCircularity, or
552 // java.lang.instrument).
553 // The second is if another thread started the resolve_super first
554 // and has not yet finished.
555 // In both cases the original caller will clean up the placeholder
556 // entry on error.
557 Klass* superk = SystemDictionary::resolve_super_or_fail(name,
558 superclassname,
559 class_loader,
560 protection_domain,
561 true,
562 CHECK_(nh));
563
564 // parallelCapable class loaders do NOT wait for parallel superclass loads to complete
565 // Serial class loaders and bootstrap classloader do wait for superclass loads
566 if (!class_loader.is_null() && is_parallelCapable(class_loader)) {
567 MutexLocker mu(SystemDictionary_lock, THREAD);
568 // Check if classloading completed while we were loading superclass or waiting
569 Klass* check = find_class(d_index, d_hash, name, loader_data);
570 if (check != NULL) {
571 // Klass is already loaded, so just return it
572 return(instanceKlassHandle(THREAD, check));
573 } else {
574 return nh;
575 }
576 }
577
578 // must loop to both handle other placeholder updates
579 // and spurious notifications
580 bool super_load_in_progress = true;
581 PlaceholderEntry* placeholder;
582 while (super_load_in_progress) {
583 MutexLocker mu(SystemDictionary_lock, THREAD);
584 // Check if classloading completed while we were loading superclass or waiting
585 Klass* check = find_class(d_index, d_hash, name, loader_data);
586 if (check != NULL) {
587 // Klass is already loaded, so just return it
588 return(instanceKlassHandle(THREAD, check));
589 } else {
590 placeholder = placeholders()->get_entry(p_index, p_hash, name, loader_data);
591 if (placeholder && placeholder->super_load_in_progress() ){
592 // Before UnsyncloadClass:
593 // We only get here if the application has released the
594 // classloader lock when another thread was in the middle of loading a
595 // superclass/superinterface for this class, and now
596 // this thread is also trying to load this class.
597 // To minimize surprises, the first thread that started to
598 // load a class should be the one to complete the loading
599 // with the classfile it initially expected.
600 // This logic has the current thread wait once it has done
601 // all the superclass/superinterface loading it can, until
602 // the original thread completes the class loading or fails
603 // If it completes we will use the resulting InstanceKlass
604 // which we will find below in the systemDictionary.
605 // We also get here for parallel bootstrap classloader
606 if (class_loader.is_null()) {
607 SystemDictionary_lock->wait();
608 } else {
609 double_lock_wait(lockObject, THREAD);
610 }
611 } else {
612 // If not in SD and not in PH, other thread's load must have failed
613 super_load_in_progress = false;
614 }
615 }
616 }
617 return (nh);
618 }
619
620
621 Klass* SystemDictionary::resolve_instance_class_or_null(Symbol* name,
622 Handle class_loader,
623 Handle protection_domain,
624 TRAPS) {
625 assert(name != NULL && !FieldType::is_array(name) &&
626 !FieldType::is_obj(name), "invalid class name");
627
628 Ticks class_load_start_time = Ticks::now();
629
630 // Fix for 4474172; see evaluation for more details
631 class_loader = Handle(THREAD, java_lang_ClassLoader::non_reflection_class_loader(class_loader()));
632 ClassLoaderData *loader_data = register_loader(class_loader, CHECK_NULL);
633
634 // Do lookup to see if class already exist and the protection domain
635 // has the right access
636 // This call uses find which checks protection domain already matches
637 // All subsequent calls use find_class, and set has_loaded_class so that
638 // before we return a result we call out to java to check for valid protection domain
639 // to allow returning the Klass* and add it to the pd_set if it is valid
640 unsigned int d_hash = dictionary()->compute_hash(name, loader_data);
641 int d_index = dictionary()->hash_to_index(d_hash);
642 Klass* probe = dictionary()->find(d_index, d_hash, name, loader_data,
643 protection_domain, THREAD);
644 if (probe != NULL) return probe;
645
646
647 // Non-bootstrap class loaders will call out to class loader and
648 // define via jvm/jni_DefineClass which will acquire the
649 // class loader object lock to protect against multiple threads
650 // defining the class in parallel by accident.
651 // This lock must be acquired here so the waiter will find
652 // any successful result in the SystemDictionary and not attempt
653 // the define
654 // ParallelCapable Classloaders and the bootstrap classloader,
655 // or all classloaders with UnsyncloadClass do not acquire lock here
656 bool DoObjectLock = true;
657 if (is_parallelCapable(class_loader)) {
658 DoObjectLock = false;
659 }
660
661 unsigned int p_hash = placeholders()->compute_hash(name, loader_data);
662 int p_index = placeholders()->hash_to_index(p_hash);
663
664 // Class is not in SystemDictionary so we have to do loading.
665 // Make sure we are synchronized on the class loader before we proceed
666 Handle lockObject = compute_loader_lock_object(class_loader, THREAD);
667 check_loader_lock_contention(lockObject, THREAD);
668 ObjectLocker ol(lockObject, THREAD, DoObjectLock);
669
670 // Check again (after locking) if class already exist in SystemDictionary
671 bool class_has_been_loaded = false;
672 bool super_load_in_progress = false;
673 bool havesupername = false;
674 instanceKlassHandle k;
675 PlaceholderEntry* placeholder;
676 Symbol* superclassname = NULL;
677
678 {
679 MutexLocker mu(SystemDictionary_lock, THREAD);
680 Klass* check = find_class(d_index, d_hash, name, loader_data);
681 if (check != NULL) {
682 // Klass is already loaded, so just return it
683 class_has_been_loaded = true;
684 k = instanceKlassHandle(THREAD, check);
685 } else {
686 placeholder = placeholders()->get_entry(p_index, p_hash, name, loader_data);
687 if (placeholder && placeholder->super_load_in_progress()) {
688 super_load_in_progress = true;
689 if (placeholder->havesupername() == true) {
690 superclassname = placeholder->supername();
691 havesupername = true;
692 }
693 }
694 }
695 }
696
697 // If the class is in the placeholder table, class loading is in progress
698 if (super_load_in_progress && havesupername==true) {
699 k = SystemDictionary::handle_parallel_super_load(name, superclassname,
700 class_loader, protection_domain, lockObject, THREAD);
701 if (HAS_PENDING_EXCEPTION) {
702 return NULL;
703 }
704 if (!k.is_null()) {
705 class_has_been_loaded = true;
706 }
707 }
708
709 bool throw_circularity_error = false;
710 if (!class_has_been_loaded) {
711 bool load_instance_added = false;
712
713 // add placeholder entry to record loading instance class
714 // Five cases:
715 // All cases need to prevent modifying bootclasssearchpath
716 // in parallel with a classload of same classname
717 // Redefineclasses uses existence of the placeholder for the duration
718 // of the class load to prevent concurrent redefinition of not completely
719 // defined classes.
720 // case 1. traditional classloaders that rely on the classloader object lock
721 // - no other need for LOAD_INSTANCE
722 // case 2. traditional classloaders that break the classloader object lock
723 // as a deadlock workaround. Detection of this case requires that
724 // this check is done while holding the classloader object lock,
725 // and that lock is still held when calling classloader's loadClass.
726 // For these classloaders, we ensure that the first requestor
727 // completes the load and other requestors wait for completion.
728 // case 3. UnsyncloadClass - don't use objectLocker
729 // With this flag, we allow parallel classloading of a
730 // class/classloader pair
731 // case4. Bootstrap classloader - don't own objectLocker
732 // This classloader supports parallelism at the classloader level,
733 // but only allows a single load of a class/classloader pair.
734 // No performance benefit and no deadlock issues.
735 // case 5. parallelCapable user level classloaders - without objectLocker
736 // Allow parallel classloading of a class/classloader pair
737
738 {
739 MutexLocker mu(SystemDictionary_lock, THREAD);
740 if (class_loader.is_null() || !is_parallelCapable(class_loader)) {
741 PlaceholderEntry* oldprobe = placeholders()->get_entry(p_index, p_hash, name, loader_data);
742 if (oldprobe) {
743 // only need check_seen_thread once, not on each loop
744 // 6341374 java/lang/Instrument with -Xcomp
745 if (oldprobe->check_seen_thread(THREAD, PlaceholderTable::LOAD_INSTANCE)) {
746 throw_circularity_error = true;
747 } else {
748 // case 1: traditional: should never see load_in_progress.
749 while (!class_has_been_loaded && oldprobe && oldprobe->instance_load_in_progress()) {
750
751 // case 4: bootstrap classloader: prevent futile classloading,
752 // wait on first requestor
753 if (class_loader.is_null()) {
754 SystemDictionary_lock->wait();
755 } else {
756 // case 2: traditional with broken classloader lock. wait on first
757 // requestor.
758 double_lock_wait(lockObject, THREAD);
759 }
760 // Check if classloading completed while we were waiting
761 Klass* check = find_class(d_index, d_hash, name, loader_data);
762 if (check != NULL) {
763 // Klass is already loaded, so just return it
764 k = instanceKlassHandle(THREAD, check);
765 class_has_been_loaded = true;
766 }
767 // check if other thread failed to load and cleaned up
768 oldprobe = placeholders()->get_entry(p_index, p_hash, name, loader_data);
769 }
770 }
771 }
772 }
773 // All cases: add LOAD_INSTANCE holding SystemDictionary_lock
774 // case 3: UnsyncloadClass || case 5: parallelCapable: allow competing threads to try
775 // LOAD_INSTANCE in parallel
776
777 if (!throw_circularity_error && !class_has_been_loaded) {
778 PlaceholderEntry* newprobe = placeholders()->find_and_add(p_index, p_hash, name, loader_data, PlaceholderTable::LOAD_INSTANCE, NULL, THREAD);
779 load_instance_added = true;
780 // For class loaders that do not acquire the classloader object lock,
781 // if they did not catch another thread holding LOAD_INSTANCE,
782 // need a check analogous to the acquire ObjectLocker/find_class
783 // i.e. now that we hold the LOAD_INSTANCE token on loading this class/CL
784 // one final check if the load has already completed
785 // class loaders holding the ObjectLock shouldn't find the class here
786 Klass* check = find_class(d_index, d_hash, name, loader_data);
787 if (check != NULL) {
788 // Klass is already loaded, so return it after checking/adding protection domain
789 k = instanceKlassHandle(THREAD, check);
790 class_has_been_loaded = true;
791 }
792 }
793 }
794
795 // must throw error outside of owning lock
796 if (throw_circularity_error) {
797 assert(!HAS_PENDING_EXCEPTION && load_instance_added == false,"circularity error cleanup");
798 ResourceMark rm(THREAD);
799 THROW_MSG_NULL(vmSymbols::java_lang_ClassCircularityError(), name->as_C_string());
800 }
801
802 if (!class_has_been_loaded) {
803
804 // Do actual loading
805 k = load_instance_class(name, class_loader, THREAD);
806
807 // For UnsyncloadClass only
808 // If they got a linkageError, check if a parallel class load succeeded.
809 // If it did, then for bytecode resolution the specification requires
810 // that we return the same result we did for the other thread, i.e. the
811 // successfully loaded InstanceKlass
812 // Should not get here for classloaders that support parallelism
813 // with the new cleaner mechanism, even with AllowParallelDefineClass
814 // Bootstrap goes through here to allow for an extra guarantee check
815 if (UnsyncloadClass || (class_loader.is_null())) {
816 if (k.is_null() && HAS_PENDING_EXCEPTION
817 && PENDING_EXCEPTION->is_a(SystemDictionary::LinkageError_klass())) {
818 MutexLocker mu(SystemDictionary_lock, THREAD);
819 Klass* check = find_class(d_index, d_hash, name, loader_data);
820 if (check != NULL) {
821 // Klass is already loaded, so just use it
822 k = instanceKlassHandle(THREAD, check);
823 CLEAR_PENDING_EXCEPTION;
824 guarantee((!class_loader.is_null()), "dup definition for bootstrap loader?");
825 }
826 }
827 }
828
829 // If everything was OK (no exceptions, no null return value), and
830 // class_loader is NOT the defining loader, do a little more bookkeeping.
831 if (!HAS_PENDING_EXCEPTION && !k.is_null() &&
832 k->class_loader() != class_loader()) {
833
834 check_constraints(d_index, d_hash, k, class_loader, false, THREAD);
835
836 // Need to check for a PENDING_EXCEPTION again; check_constraints
837 // can throw and doesn't use the CHECK macro.
838 if (!HAS_PENDING_EXCEPTION) {
839 { // Grabbing the Compile_lock prevents systemDictionary updates
840 // during compilations.
841 MutexLocker mu(Compile_lock, THREAD);
842 update_dictionary(d_index, d_hash, p_index, p_hash,
843 k, class_loader, THREAD);
844 }
845
846 if (JvmtiExport::should_post_class_load()) {
847 Thread *thread = THREAD;
848 assert(thread->is_Java_thread(), "thread->is_Java_thread()");
849 JvmtiExport::post_class_load((JavaThread *) thread, k());
850 }
851 }
852 }
853 } // load_instance_class loop
854
855 if (load_instance_added == true) {
856 // clean up placeholder entries for LOAD_INSTANCE success or error
857 // This brackets the SystemDictionary updates for both defining
858 // and initiating loaders
859 MutexLocker mu(SystemDictionary_lock, THREAD);
860 placeholders()->find_and_remove(p_index, p_hash, name, loader_data, PlaceholderTable::LOAD_INSTANCE, THREAD);
861 SystemDictionary_lock->notify_all();
862 }
863 }
864
865 if (HAS_PENDING_EXCEPTION || k.is_null()) {
866 return NULL;
867 }
868
869 post_class_load_event(class_load_start_time, k, class_loader);
870
871 #ifdef ASSERT
872 {
873 ClassLoaderData* loader_data = k->class_loader_data();
874 MutexLocker mu(SystemDictionary_lock, THREAD);
875 Klass* kk = find_class(name, loader_data);
876 assert(kk == k(), "should be present in dictionary");
877 }
878 #endif
879
880 // return if the protection domain in NULL
881 if (protection_domain() == NULL) return k();
882
883 // Check the protection domain has the right access
884 {
885 MutexLocker mu(SystemDictionary_lock, THREAD);
886 // Note that we have an entry, and entries can be deleted only during GC,
887 // so we cannot allow GC to occur while we're holding this entry.
888 // We're using a No_Safepoint_Verifier to catch any place where we
889 // might potentially do a GC at all.
890 // Dictionary::do_unloading() asserts that classes in SD are only
891 // unloaded at a safepoint. Anonymous classes are not in SD.
892 No_Safepoint_Verifier nosafepoint;
893 if (dictionary()->is_valid_protection_domain(d_index, d_hash, name,
894 loader_data,
895 protection_domain)) {
896 return k();
897 }
898 }
899
900 // Verify protection domain. If it fails an exception is thrown
901 validate_protection_domain(k, class_loader, protection_domain, CHECK_NULL);
902
903 return k();
904 }
905
906
907 // This routine does not lock the system dictionary.
908 //
909 // Since readers don't hold a lock, we must make sure that system
910 // dictionary entries are only removed at a safepoint (when only one
911 // thread is running), and are added to in a safe way (all links must
912 // be updated in an MT-safe manner).
913 //
914 // Callers should be aware that an entry could be added just after
915 // _dictionary->bucket(index) is read here, so the caller will not see
916 // the new entry.
917
918 Klass* SystemDictionary::find(Symbol* class_name,
919 Handle class_loader,
920 Handle protection_domain,
921 TRAPS) {
922
923 // The result of this call should be consistent with the result
924 // of the call to resolve_instance_class_or_null().
925 // See evaluation 6790209 and 4474172 for more details.
926 class_loader = Handle(THREAD, java_lang_ClassLoader::non_reflection_class_loader(class_loader()));
927 ClassLoaderData* loader_data = ClassLoaderData::class_loader_data_or_null(class_loader());
928
929 if (loader_data == NULL) {
930 // If the ClassLoaderData has not been setup,
931 // then the class loader has no entries in the dictionary.
932 return NULL;
933 }
934
935 unsigned int d_hash = dictionary()->compute_hash(class_name, loader_data);
936 int d_index = dictionary()->hash_to_index(d_hash);
937
938 {
939 // Note that we have an entry, and entries can be deleted only during GC,
940 // so we cannot allow GC to occur while we're holding this entry.
941 // We're using a No_Safepoint_Verifier to catch any place where we
942 // might potentially do a GC at all.
943 // Dictionary::do_unloading() asserts that classes in SD are only
944 // unloaded at a safepoint. Anonymous classes are not in SD.
945 No_Safepoint_Verifier nosafepoint;
946 return dictionary()->find(d_index, d_hash, class_name, loader_data,
947 protection_domain, THREAD);
948 }
949 }
950
951
952 // Look for a loaded instance or array klass by name. Do not do any loading.
953 // return NULL in case of error.
954 Klass* SystemDictionary::find_instance_or_array_klass(Symbol* class_name,
955 Handle class_loader,
956 Handle protection_domain,
957 TRAPS) {
958 Klass* k = NULL;
959 assert(class_name != NULL, "class name must be non NULL");
960
961 if (FieldType::is_array(class_name)) {
962 // The name refers to an array. Parse the name.
963 // dimension and object_key in FieldArrayInfo are assigned as a
964 // side-effect of this call
965 FieldArrayInfo fd;
966 BasicType t = FieldType::get_array_info(class_name, fd, CHECK_(NULL));
967 if (t != T_OBJECT) {
968 k = Universe::typeArrayKlassObj(t);
969 } else {
970 k = SystemDictionary::find(fd.object_key(), class_loader, protection_domain, THREAD);
971 }
972 if (k != NULL) {
973 k = k->array_klass_or_null(fd.dimension());
974 }
975 } else {
976 k = find(class_name, class_loader, protection_domain, THREAD);
977 }
978 return k;
979 }
980
981 // Note: this method is much like resolve_from_stream, but
982 // updates no supplemental data structures.
983 // TODO consolidate the two methods with a helper routine?
984 Klass* SystemDictionary::parse_stream(Symbol* class_name,
985 Handle class_loader,
986 Handle protection_domain,
987 ClassFileStream* st,
988 KlassHandle host_klass,
989 GrowableArray<Handle>* cp_patches,
990 TRAPS) {
991 TempNewSymbol parsed_name = NULL;
992
993 Ticks class_load_start_time = Ticks::now();
994
995 ClassLoaderData* loader_data;
996 if (host_klass.not_null()) {
997 // Create a new CLD for anonymous class, that uses the same class loader
998 // as the host_klass
999 guarantee(host_klass->class_loader() == class_loader(), "should be the same");
1000 guarantee(!DumpSharedSpaces, "must not create anonymous classes when dumping");
1001 loader_data = ClassLoaderData::anonymous_class_loader_data(class_loader(), CHECK_NULL);
1002 loader_data->record_dependency(host_klass(), CHECK_NULL);
1003 } else {
1004 loader_data = ClassLoaderData::class_loader_data(class_loader());
1005 }
1006
1007 // Parse the stream. Note that we do this even though this klass might
1008 // already be present in the SystemDictionary, otherwise we would not
1009 // throw potential ClassFormatErrors.
1010 //
1011 // Note: "name" is updated.
1012
1013 instanceKlassHandle k = ClassFileParser(st).parseClassFile(class_name,
1014 loader_data,
1015 protection_domain,
1016 host_klass,
1017 cp_patches,
1018 parsed_name,
1019 true,
1020 THREAD);
1021
1022
1023 if (host_klass.not_null() && k.not_null()) {
1024 // If it's anonymous, initialize it now, since nobody else will.
1025
1026 {
1027 MutexLocker mu_r(Compile_lock, THREAD);
1028
1029 // Add to class hierarchy, initialize vtables, and do possible
1030 // deoptimizations.
1031 add_to_hierarchy(k, CHECK_NULL); // No exception, but can block
1032
1033 // But, do not add to system dictionary.
1034
1035 // compiled code dependencies need to be validated anyway
1036 notice_modification();
1037 }
1038
1039 // Rewrite and patch constant pool here.
1040 k->link_class(CHECK_NULL);
1041 if (cp_patches != NULL) {
1042 k->constants()->patch_resolved_references(cp_patches);
1043 }
1044 k->eager_initialize(CHECK_NULL);
1045
1046 // notify jvmti
1047 if (JvmtiExport::should_post_class_load()) {
1048 assert(THREAD->is_Java_thread(), "thread->is_Java_thread()");
1049 JvmtiExport::post_class_load((JavaThread *) THREAD, k());
1050 }
1051
1052 post_class_load_event(class_load_start_time, k, class_loader);
1053 }
1054 assert(host_klass.not_null() || cp_patches == NULL,
1055 "cp_patches only found with host_klass");
1056
1057 return k();
1058 }
1059
1060 // Add a klass to the system from a stream (called by jni_DefineClass and
1061 // JVM_DefineClass).
1062 // Note: class_name can be NULL. In that case we do not know the name of
1063 // the class until we have parsed the stream.
1064
1065 Klass* SystemDictionary::resolve_from_stream(Symbol* class_name,
1066 Handle class_loader,
1067 Handle protection_domain,
1068 ClassFileStream* st,
1069 bool verify,
1070 TRAPS) {
1071
1072 // Classloaders that support parallelism, e.g. bootstrap classloader,
1073 // or all classloaders with UnsyncloadClass do not acquire lock here
1074 bool DoObjectLock = true;
1075 if (is_parallelCapable(class_loader)) {
1076 DoObjectLock = false;
1077 }
1078
1079 ClassLoaderData* loader_data = register_loader(class_loader, CHECK_NULL);
1080
1081 // Make sure we are synchronized on the class loader before we proceed
1082 Handle lockObject = compute_loader_lock_object(class_loader, THREAD);
1083 check_loader_lock_contention(lockObject, THREAD);
1084 ObjectLocker ol(lockObject, THREAD, DoObjectLock);
1085
1086 TempNewSymbol parsed_name = NULL;
1087
1088 // Parse the stream. Note that we do this even though this klass might
1089 // already be present in the SystemDictionary, otherwise we would not
1090 // throw potential ClassFormatErrors.
1091 //
1092 // Note: "name" is updated.
1093
1094 instanceKlassHandle k;
1095
1096 #if INCLUDE_CDS
1097 k = SystemDictionaryShared::lookup_from_stream(class_name,
1098 class_loader,
1099 protection_domain,
1100 st,
1101 verify,
1102 CHECK_NULL);
1103 #endif
1104
1105 if (k.not_null()) {
1106 parsed_name = k->name();
1107 } else {
1108 if (st->buffer() == NULL) {
1109 return NULL;
1110 }
1111 k = ClassFileParser(st).parseClassFile(class_name,
1112 loader_data,
1113 protection_domain,
1114 parsed_name,
1115 verify,
1116 THREAD);
1117 }
1118
1119 const char* pkg = "java/";
1120 if (!HAS_PENDING_EXCEPTION &&
1121 !class_loader.is_null() &&
1122 parsed_name != NULL &&
1123 !strncmp((const char*)parsed_name->bytes(), pkg, strlen(pkg))) {
1124 // It is illegal to define classes in the "java." package from
1125 // JVM_DefineClass or jni_DefineClass unless you're the bootclassloader
1126 ResourceMark rm(THREAD);
1127 char* name = parsed_name->as_C_string();
1128 char* index = strrchr(name, '/');
1129 *index = '\0'; // chop to just the package name
1130 while ((index = strchr(name, '/')) != NULL) {
1131 *index = '.'; // replace '/' with '.' in package name
1132 }
1133 const char* fmt = "Prohibited package name: %s";
1134 size_t len = strlen(fmt) + strlen(name);
1135 char* message = NEW_RESOURCE_ARRAY(char, len);
1136 jio_snprintf(message, len, fmt, name);
1137 Exceptions::_throw_msg(THREAD_AND_LOCATION,
1138 vmSymbols::java_lang_SecurityException(), message);
1139 }
1140
1141 if (!HAS_PENDING_EXCEPTION) {
1142 assert(parsed_name != NULL, "Sanity");
1143 assert(class_name == NULL || class_name == parsed_name, "name mismatch");
1144 // Verification prevents us from creating names with dots in them, this
1145 // asserts that that's the case.
1146 assert(is_internal_format(parsed_name),
1147 "external class name format used internally");
1148
1149 // Add class just loaded
1150 // If a class loader supports parallel classloading handle parallel define requests
1151 // find_or_define_instance_class may return a different InstanceKlass
1152 if (is_parallelCapable(class_loader)) {
1153 k = find_or_define_instance_class(class_name, class_loader, k, THREAD);
1154 } else {
1155 define_instance_class(k, THREAD);
1156 }
1157 }
1158
1159 // Make sure we have an entry in the SystemDictionary on success
1160 debug_only( {
1161 if (!HAS_PENDING_EXCEPTION) {
1162 assert(parsed_name != NULL, "parsed_name is still null?");
1163 Symbol* h_name = k->name();
1164 ClassLoaderData *defining_loader_data = k->class_loader_data();
1165
1166 MutexLocker mu(SystemDictionary_lock, THREAD);
1167
1168 Klass* check = find_class(parsed_name, loader_data);
1169 assert(check == k(), "should be present in the dictionary");
1170
1171 Klass* check2 = find_class(h_name, defining_loader_data);
1172 assert(check == check2, "name inconsistancy in SystemDictionary");
1173 }
1174 } );
1175
1176 return k();
1177 }
1178
1179 #if INCLUDE_CDS
1180 void SystemDictionary::set_shared_dictionary(HashtableBucket<mtClass>* t, int length,
1181 int number_of_entries) {
1182 assert(length == _nof_buckets * sizeof(HashtableBucket<mtClass>),
1183 "bad shared dictionary size.");
1184 _shared_dictionary = new Dictionary(_nof_buckets, t, number_of_entries);
1185 }
1186
1187
1188 // If there is a shared dictionary, then find the entry for the
1189 // given shared system class, if any.
1190
1191 Klass* SystemDictionary::find_shared_class(Symbol* class_name) {
1192 if (shared_dictionary() != NULL) {
1193 unsigned int d_hash = shared_dictionary()->compute_hash(class_name, NULL);
1194 int d_index = shared_dictionary()->hash_to_index(d_hash);
1195
1196 return shared_dictionary()->find_shared_class(d_index, d_hash, class_name);
1197 } else {
1198 return NULL;
1199 }
1200 }
1201
1202
1203 // Load a class from the shared spaces (found through the shared system
1204 // dictionary). Force the superclass and all interfaces to be loaded.
1205 // Update the class definition to include sibling classes and no
1206 // subclasses (yet). [Classes in the shared space are not part of the
1207 // object hierarchy until loaded.]
1208
1209 instanceKlassHandle SystemDictionary::load_shared_class(
1210 Symbol* class_name, Handle class_loader, TRAPS) {
1211 instanceKlassHandle ik (THREAD, find_shared_class(class_name));
1212 // Make sure we only return the boot class for the NULL classloader.
1213 if (ik.not_null() &&
1214 SharedClassUtil::is_shared_boot_class(ik()) && class_loader.is_null()) {
1215 Handle protection_domain;
1216 return load_shared_class(ik, class_loader, protection_domain, THREAD);
1217 }
1218 return instanceKlassHandle();
1219 }
1220
1221 instanceKlassHandle SystemDictionary::load_shared_class(instanceKlassHandle ik,
1222 Handle class_loader,
1223 Handle protection_domain, TRAPS) {
1224 if (ik.not_null()) {
1225 instanceKlassHandle nh = instanceKlassHandle(); // null Handle
1226 Symbol* class_name = ik->name();
1227
1228 // Found the class, now load the superclass and interfaces. If they
1229 // are shared, add them to the main system dictionary and reset
1230 // their hierarchy references (supers, subs, and interfaces).
1231
1232 if (ik->super() != NULL) {
1233 Symbol* cn = ik->super()->name();
1234 Klass *s = resolve_super_or_fail(class_name, cn,
1235 class_loader, protection_domain, true, CHECK_(nh));
1236 if (s != ik->super()) {
1237 // The dynamically resolved super class is not the same as the one we used during dump time,
1238 // so we cannot use ik.
1239 return nh;
1240 }
1241 }
1242
1243 Array<Klass*>* interfaces = ik->local_interfaces();
1244 int num_interfaces = interfaces->length();
1245 for (int index = 0; index < num_interfaces; index++) {
1246 Klass* k = interfaces->at(index);
1247
1248 // Note: can not use InstanceKlass::cast here because
1249 // interfaces' InstanceKlass's C++ vtbls haven't been
1250 // reinitialized yet (they will be once the interface classes
1251 // are loaded)
1252 Symbol* name = k->name();
1253 Klass* i = resolve_super_or_fail(class_name, name, class_loader, protection_domain, false, CHECK_(nh));
1254 if (k != i) {
1255 // The dynamically resolved interface class is not the same as the one we used during dump time,
1256 // so we cannot use ik.
1257 return nh;
1258 }
1259 }
1260
1261 // Adjust methods to recover missing data. They need addresses for
1262 // interpreter entry points and their default native method address
1263 // must be reset.
1264
1265 // Updating methods must be done under a lock so multiple
1266 // threads don't update these in parallel
1267 //
1268 // Shared classes are all currently loaded by either the bootstrap or
1269 // internal parallel class loaders, so this will never cause a deadlock
1270 // on a custom class loader lock.
1271
1272 ClassLoaderData* loader_data = ClassLoaderData::class_loader_data(class_loader());
1273 {
1274 Handle lockObject = compute_loader_lock_object(class_loader, THREAD);
1275 check_loader_lock_contention(lockObject, THREAD);
1276 ObjectLocker ol(lockObject, THREAD, true);
1277 ik->restore_unshareable_info(loader_data, protection_domain, CHECK_(nh));
1278 }
1279
1280 if (TraceClassLoading) {
1281 ResourceMark rm;
1282 tty->print("[Loaded %s", ik->external_name());
1283 tty->print(" from shared objects file");
1284 if (class_loader.not_null()) {
1285 tty->print(" by %s", loader_data->loader_name());
1286 }
1287 tty->print_cr("]");
1288 }
1289
1290 if (log_is_enabled(Debug, classload)) {
1291 ik()->print_loading_log(LogLevel::Debug, loader_data, NULL);
1292 }
1293 if (log_is_enabled(Trace, classload)) {
1294 ik()->print_loading_log(LogLevel::Trace, loader_data, NULL);
1295 }
1296
1297 if (DumpLoadedClassList != NULL && classlist_file->is_open()) {
1298 // Only dump the classes that can be stored into CDS archive
1299 if (SystemDictionaryShared::is_sharing_possible(loader_data)) {
1300 ResourceMark rm(THREAD);
1301 classlist_file->print_cr("%s", ik->name()->as_C_string());
1302 classlist_file->flush();
1303 }
1304 }
1305
1306 // notify a class loaded from shared object
1307 ClassLoadingService::notify_class_loaded(ik(), true /* shared class */);
1308 }
1309 return ik;
1310 }
1311 #endif // INCLUDE_CDS
1312
1313 instanceKlassHandle SystemDictionary::load_instance_class(Symbol* class_name, Handle class_loader, TRAPS) {
1314 instanceKlassHandle nh = instanceKlassHandle(); // null Handle
1315 if (class_loader.is_null()) {
1316
1317 // Search the shared system dictionary for classes preloaded into the
1318 // shared spaces.
1319 instanceKlassHandle k;
1320 {
1321 #if INCLUDE_CDS
1322 PerfTraceTime vmtimer(ClassLoader::perf_shared_classload_time());
1323 k = load_shared_class(class_name, class_loader, THREAD);
1324 #endif
1325 }
1326
1327 if (k.is_null()) {
1328 // Use VM class loader
1329 PerfTraceTime vmtimer(ClassLoader::perf_sys_classload_time());
1330 k = ClassLoader::load_classfile(class_name, CHECK_(nh));
1331 }
1332
1333 // find_or_define_instance_class may return a different InstanceKlass
1334 if (!k.is_null()) {
1335 k = find_or_define_instance_class(class_name, class_loader, k, CHECK_(nh));
1336 }
1337 return k;
1338 } else {
1339 // Use user specified class loader to load class. Call loadClass operation on class_loader.
1340 ResourceMark rm(THREAD);
1341
1342 assert(THREAD->is_Java_thread(), "must be a JavaThread");
1343 JavaThread* jt = (JavaThread*) THREAD;
1344
1345 PerfClassTraceTime vmtimer(ClassLoader::perf_app_classload_time(),
1346 ClassLoader::perf_app_classload_selftime(),
1347 ClassLoader::perf_app_classload_count(),
1348 jt->get_thread_stat()->perf_recursion_counts_addr(),
1349 jt->get_thread_stat()->perf_timers_addr(),
1350 PerfClassTraceTime::CLASS_LOAD);
1351
1352 Handle s = java_lang_String::create_from_symbol(class_name, CHECK_(nh));
1353 // Translate to external class name format, i.e., convert '/' chars to '.'
1354 Handle string = java_lang_String::externalize_classname(s, CHECK_(nh));
1355
1356 JavaValue result(T_OBJECT);
1357
1358 KlassHandle spec_klass (THREAD, SystemDictionary::ClassLoader_klass());
1359
1360 // Call public unsynchronized loadClass(String) directly for all class loaders
1361 // for parallelCapable class loaders. JDK >=7, loadClass(String, boolean) will
1362 // acquire a class-name based lock rather than the class loader object lock.
1363 // JDK < 7 already acquire the class loader lock in loadClass(String, boolean),
1364 // so the call to loadClassInternal() was not required.
1365 //
1366 // UnsyncloadClass flag means both call loadClass(String) and do
1367 // not acquire the class loader lock even for class loaders that are
1368 // not parallelCapable. This was a risky transitional
1369 // flag for diagnostic purposes only. It is risky to call
1370 // custom class loaders without synchronization.
1371 // WARNING If a custom class loader does NOT synchronizer findClass, or callers of
1372 // findClass, the UnsyncloadClass flag risks unexpected timing bugs in the field.
1373 // Do NOT assume this will be supported in future releases.
1374 //
1375 // Added MustCallLoadClassInternal in case we discover in the field
1376 // a customer that counts on this call
1377 if (MustCallLoadClassInternal && has_loadClassInternal()) {
1378 JavaCalls::call_special(&result,
1379 class_loader,
1380 spec_klass,
1381 vmSymbols::loadClassInternal_name(),
1382 vmSymbols::string_class_signature(),
1383 string,
1384 CHECK_(nh));
1385 } else {
1386 JavaCalls::call_virtual(&result,
1387 class_loader,
1388 spec_klass,
1389 vmSymbols::loadClass_name(),
1390 vmSymbols::string_class_signature(),
1391 string,
1392 CHECK_(nh));
1393 }
1394
1395 assert(result.get_type() == T_OBJECT, "just checking");
1396 oop obj = (oop) result.get_jobject();
1397
1398 // Primitive classes return null since forName() can not be
1399 // used to obtain any of the Class objects representing primitives or void
1400 if ((obj != NULL) && !(java_lang_Class::is_primitive(obj))) {
1401 instanceKlassHandle k =
1402 instanceKlassHandle(THREAD, java_lang_Class::as_Klass(obj));
1403 // For user defined Java class loaders, check that the name returned is
1404 // the same as that requested. This check is done for the bootstrap
1405 // loader when parsing the class file.
1406 if (class_name == k->name()) {
1407 return k;
1408 }
1409 }
1410 // Class is not found or has the wrong name, return NULL
1411 return nh;
1412 }
1413 }
1414
1415 void SystemDictionary::define_instance_class(instanceKlassHandle k, TRAPS) {
1416
1417 ClassLoaderData* loader_data = k->class_loader_data();
1418 Handle class_loader_h(THREAD, loader_data->class_loader());
1419
1420 // for bootstrap and other parallel classloaders don't acquire lock,
1421 // use placeholder token
1422 // If a parallelCapable class loader calls define_instance_class instead of
1423 // find_or_define_instance_class to get here, we have a timing
1424 // hole with systemDictionary updates and check_constraints
1425 if (!class_loader_h.is_null() && !is_parallelCapable(class_loader_h)) {
1426 assert(ObjectSynchronizer::current_thread_holds_lock((JavaThread*)THREAD,
1427 compute_loader_lock_object(class_loader_h, THREAD)),
1428 "define called without lock");
1429 }
1430
1431 // Check class-loading constraints. Throw exception if violation is detected.
1432 // Grabs and releases SystemDictionary_lock
1433 // The check_constraints/find_class call and update_dictionary sequence
1434 // must be "atomic" for a specific class/classloader pair so we never
1435 // define two different instanceKlasses for that class/classloader pair.
1436 // Existing classloaders will call define_instance_class with the
1437 // classloader lock held
1438 // Parallel classloaders will call find_or_define_instance_class
1439 // which will require a token to perform the define class
1440 Symbol* name_h = k->name();
1441 unsigned int d_hash = dictionary()->compute_hash(name_h, loader_data);
1442 int d_index = dictionary()->hash_to_index(d_hash);
1443 check_constraints(d_index, d_hash, k, class_loader_h, true, CHECK);
1444
1445 // Register class just loaded with class loader (placed in Vector)
1446 // Note we do this before updating the dictionary, as this can
1447 // fail with an OutOfMemoryError (if it does, we will *not* put this
1448 // class in the dictionary and will not update the class hierarchy).
1449 // JVMTI FollowReferences needs to find the classes this way.
1450 if (k->class_loader() != NULL) {
1451 methodHandle m(THREAD, Universe::loader_addClass_method());
1452 JavaValue result(T_VOID);
1453 JavaCallArguments args(class_loader_h);
1454 args.push_oop(Handle(THREAD, k->java_mirror()));
1455 JavaCalls::call(&result, m, &args, CHECK);
1456 }
1457
1458 // Add the new class. We need recompile lock during update of CHA.
1459 {
1460 unsigned int p_hash = placeholders()->compute_hash(name_h, loader_data);
1461 int p_index = placeholders()->hash_to_index(p_hash);
1462
1463 MutexLocker mu_r(Compile_lock, THREAD);
1464
1465 // Add to class hierarchy, initialize vtables, and do possible
1466 // deoptimizations.
1467 add_to_hierarchy(k, CHECK); // No exception, but can block
1468
1469 // Add to systemDictionary - so other classes can see it.
1470 // Grabs and releases SystemDictionary_lock
1471 update_dictionary(d_index, d_hash, p_index, p_hash,
1472 k, class_loader_h, THREAD);
1473 }
1474 k->eager_initialize(THREAD);
1475
1476 // notify jvmti
1477 if (JvmtiExport::should_post_class_load()) {
1478 assert(THREAD->is_Java_thread(), "thread->is_Java_thread()");
1479 JvmtiExport::post_class_load((JavaThread *) THREAD, k());
1480
1481 }
1482
1483 }
1484
1485 // Support parallel classloading
1486 // All parallel class loaders, including bootstrap classloader
1487 // lock a placeholder entry for this class/class_loader pair
1488 // to allow parallel defines of different classes for this class loader
1489 // With AllowParallelDefine flag==true, in case they do not synchronize around
1490 // FindLoadedClass/DefineClass, calls, we check for parallel
1491 // loading for them, wait if a defineClass is in progress
1492 // and return the initial requestor's results
1493 // This flag does not apply to the bootstrap classloader.
1494 // With AllowParallelDefine flag==false, call through to define_instance_class
1495 // which will throw LinkageError: duplicate class definition.
1496 // False is the requested default.
1497 // For better performance, the class loaders should synchronize
1498 // findClass(), i.e. FindLoadedClass/DefineClassIfAbsent or they
1499 // potentially waste time reading and parsing the bytestream.
1500 // Note: VM callers should ensure consistency of k/class_name,class_loader
1501 instanceKlassHandle SystemDictionary::find_or_define_instance_class(Symbol* class_name, Handle class_loader, instanceKlassHandle k, TRAPS) {
1502
1503 instanceKlassHandle nh = instanceKlassHandle(); // null Handle
1504 Symbol* name_h = k->name(); // passed in class_name may be null
1505 ClassLoaderData* loader_data = class_loader_data(class_loader);
1506
1507 unsigned int d_hash = dictionary()->compute_hash(name_h, loader_data);
1508 int d_index = dictionary()->hash_to_index(d_hash);
1509
1510 // Hold SD lock around find_class and placeholder creation for DEFINE_CLASS
1511 unsigned int p_hash = placeholders()->compute_hash(name_h, loader_data);
1512 int p_index = placeholders()->hash_to_index(p_hash);
1513 PlaceholderEntry* probe;
1514
1515 {
1516 MutexLocker mu(SystemDictionary_lock, THREAD);
1517 // First check if class already defined
1518 if (UnsyncloadClass || (is_parallelDefine(class_loader))) {
1519 Klass* check = find_class(d_index, d_hash, name_h, loader_data);
1520 if (check != NULL) {
1521 return(instanceKlassHandle(THREAD, check));
1522 }
1523 }
1524
1525 // Acquire define token for this class/classloader
1526 probe = placeholders()->find_and_add(p_index, p_hash, name_h, loader_data, PlaceholderTable::DEFINE_CLASS, NULL, THREAD);
1527 // Wait if another thread defining in parallel
1528 // All threads wait - even those that will throw duplicate class: otherwise
1529 // caller is surprised by LinkageError: duplicate, but findLoadedClass fails
1530 // if other thread has not finished updating dictionary
1531 while (probe->definer() != NULL) {
1532 SystemDictionary_lock->wait();
1533 }
1534 // Only special cases allow parallel defines and can use other thread's results
1535 // Other cases fall through, and may run into duplicate defines
1536 // caught by finding an entry in the SystemDictionary
1537 if ((UnsyncloadClass || is_parallelDefine(class_loader)) && (probe->instance_klass() != NULL)) {
1538 placeholders()->find_and_remove(p_index, p_hash, name_h, loader_data, PlaceholderTable::DEFINE_CLASS, THREAD);
1539 SystemDictionary_lock->notify_all();
1540 #ifdef ASSERT
1541 Klass* check = find_class(d_index, d_hash, name_h, loader_data);
1542 assert(check != NULL, "definer missed recording success");
1543 #endif
1544 return(instanceKlassHandle(THREAD, probe->instance_klass()));
1545 } else {
1546 // This thread will define the class (even if earlier thread tried and had an error)
1547 probe->set_definer(THREAD);
1548 }
1549 }
1550
1551 define_instance_class(k, THREAD);
1552
1553 Handle linkage_exception = Handle(); // null handle
1554
1555 // definer must notify any waiting threads
1556 {
1557 MutexLocker mu(SystemDictionary_lock, THREAD);
1558 PlaceholderEntry* probe = placeholders()->get_entry(p_index, p_hash, name_h, loader_data);
1559 assert(probe != NULL, "DEFINE_CLASS placeholder lost?");
1560 if (probe != NULL) {
1561 if (HAS_PENDING_EXCEPTION) {
1562 linkage_exception = Handle(THREAD,PENDING_EXCEPTION);
1563 CLEAR_PENDING_EXCEPTION;
1564 } else {
1565 probe->set_instance_klass(k());
1566 }
1567 probe->set_definer(NULL);
1568 placeholders()->find_and_remove(p_index, p_hash, name_h, loader_data, PlaceholderTable::DEFINE_CLASS, THREAD);
1569 SystemDictionary_lock->notify_all();
1570 }
1571 }
1572
1573 // Can't throw exception while holding lock due to rank ordering
1574 if (linkage_exception() != NULL) {
1575 THROW_OOP_(linkage_exception(), nh); // throws exception and returns
1576 }
1577
1578 return k;
1579 }
1580 Handle SystemDictionary::compute_loader_lock_object(Handle class_loader, TRAPS) {
1581 // If class_loader is NULL we synchronize on _system_loader_lock_obj
1582 if (class_loader.is_null()) {
1583 return Handle(THREAD, _system_loader_lock_obj);
1584 } else {
1585 return class_loader;
1586 }
1587 }
1588
1589 // This method is added to check how often we have to wait to grab loader
1590 // lock. The results are being recorded in the performance counters defined in
1591 // ClassLoader::_sync_systemLoaderLockContentionRate and
1592 // ClassLoader::_sync_nonSystemLoaderLockConteionRate.
1593 void SystemDictionary::check_loader_lock_contention(Handle loader_lock, TRAPS) {
1594 if (!UsePerfData) {
1595 return;
1596 }
1597
1598 assert(!loader_lock.is_null(), "NULL lock object");
1599
1600 if (ObjectSynchronizer::query_lock_ownership((JavaThread*)THREAD, loader_lock)
1601 == ObjectSynchronizer::owner_other) {
1602 // contention will likely happen, so increment the corresponding
1603 // contention counter.
1604 if (loader_lock() == _system_loader_lock_obj) {
1605 ClassLoader::sync_systemLoaderLockContentionRate()->inc();
1606 } else {
1607 ClassLoader::sync_nonSystemLoaderLockContentionRate()->inc();
1608 }
1609 }
1610 }
1611
1612 // ----------------------------------------------------------------------------
1613 // Lookup
1614
1615 Klass* SystemDictionary::find_class(int index, unsigned int hash,
1616 Symbol* class_name,
1617 ClassLoaderData* loader_data) {
1618 assert_locked_or_safepoint(SystemDictionary_lock);
1619 assert (index == dictionary()->index_for(class_name, loader_data),
1620 "incorrect index?");
1621
1622 Klass* k = dictionary()->find_class(index, hash, class_name, loader_data);
1623 return k;
1624 }
1625
1626
1627 // Basic find on classes in the midst of being loaded
1628 Symbol* SystemDictionary::find_placeholder(Symbol* class_name,
1629 ClassLoaderData* loader_data) {
1630 assert_locked_or_safepoint(SystemDictionary_lock);
1631 unsigned int p_hash = placeholders()->compute_hash(class_name, loader_data);
1632 int p_index = placeholders()->hash_to_index(p_hash);
1633 return placeholders()->find_entry(p_index, p_hash, class_name, loader_data);
1634 }
1635
1636
1637 // Used for assertions and verification only
1638 Klass* SystemDictionary::find_class(Symbol* class_name, ClassLoaderData* loader_data) {
1639 #ifndef ASSERT
1640 guarantee(VerifyBeforeGC ||
1641 VerifyDuringGC ||
1642 VerifyBeforeExit ||
1643 VerifyDuringStartup ||
1644 VerifyAfterGC, "too expensive");
1645 #endif
1646 assert_locked_or_safepoint(SystemDictionary_lock);
1647
1648 // First look in the loaded class array
1649 unsigned int d_hash = dictionary()->compute_hash(class_name, loader_data);
1650 int d_index = dictionary()->hash_to_index(d_hash);
1651 return find_class(d_index, d_hash, class_name, loader_data);
1652 }
1653
1654
1655 // Get the next class in the diictionary.
1656 Klass* SystemDictionary::try_get_next_class() {
1657 return dictionary()->try_get_next_class();
1658 }
1659
1660
1661 // ----------------------------------------------------------------------------
1662 // Update hierachy. This is done before the new klass has been added to the SystemDictionary. The Recompile_lock
1663 // is held, to ensure that the compiler is not using the class hierachy, and that deoptimization will kick in
1664 // before a new class is used.
1665
1666 void SystemDictionary::add_to_hierarchy(instanceKlassHandle k, TRAPS) {
1667 assert(k.not_null(), "just checking");
1668 assert_locked_or_safepoint(Compile_lock);
1669
1670 // Link into hierachy. Make sure the vtables are initialized before linking into
1671 k->append_to_sibling_list(); // add to superklass/sibling list
1672 k->process_interfaces(THREAD); // handle all "implements" declarations
1673 k->set_init_state(InstanceKlass::loaded);
1674 // Now flush all code that depended on old class hierarchy.
1675 // Note: must be done *after* linking k into the hierarchy (was bug 12/9/97)
1676 // Also, first reinitialize vtable because it may have gotten out of synch
1677 // while the new class wasn't connected to the class hierarchy.
1678 CodeCache::flush_dependents_on(k);
1679 }
1680
1681 // ----------------------------------------------------------------------------
1682 // GC support
1683
1684 // Following roots during mark-sweep is separated in two phases.
1685 //
1686 // The first phase follows preloaded classes and all other system
1687 // classes, since these will never get unloaded anyway.
1688 //
1689 // The second phase removes (unloads) unreachable classes from the
1690 // system dictionary and follows the remaining classes' contents.
1691
1692 void SystemDictionary::always_strong_oops_do(OopClosure* blk) {
1693 roots_oops_do(blk, NULL);
1694 }
1695
1696 void SystemDictionary::always_strong_classes_do(KlassClosure* closure) {
1697 // Follow all system classes and temporary placeholders in dictionary
1698 dictionary()->always_strong_classes_do(closure);
1699
1700 // Placeholders. These represent classes we're actively loading.
1701 placeholders()->classes_do(closure);
1702 }
1703
1704 // Calculate a "good" systemdictionary size based
1705 // on predicted or current loaded classes count
1706 int SystemDictionary::calculate_systemdictionary_size(int classcount) {
1707 int newsize = _old_default_sdsize;
1708 if ((classcount > 0) && !DumpSharedSpaces) {
1709 int desiredsize = classcount/_average_depth_goal;
1710 for (newsize = _primelist[_sdgeneration]; _sdgeneration < _prime_array_size -1;
1711 newsize = _primelist[++_sdgeneration]) {
1712 if (desiredsize <= newsize) {
1713 break;
1714 }
1715 }
1716 }
1717 return newsize;
1718 }
1719
1720 #ifdef ASSERT
1721 class VerifySDReachableAndLiveClosure : public OopClosure {
1722 private:
1723 BoolObjectClosure* _is_alive;
1724
1725 template <class T> void do_oop_work(T* p) {
1726 oop obj = oopDesc::load_decode_heap_oop(p);
1727 guarantee(_is_alive->do_object_b(obj), "Oop in system dictionary must be live");
1728 }
1729
1730 public:
1731 VerifySDReachableAndLiveClosure(BoolObjectClosure* is_alive) : OopClosure(), _is_alive(is_alive) { }
1732
1733 virtual void do_oop(oop* p) { do_oop_work(p); }
1734 virtual void do_oop(narrowOop* p) { do_oop_work(p); }
1735 };
1736 #endif
1737
1738 // Assumes classes in the SystemDictionary are only unloaded at a safepoint
1739 // Note: anonymous classes are not in the SD.
1740 bool SystemDictionary::do_unloading(BoolObjectClosure* is_alive,
1741 bool clean_previous_versions) {
1742 // First, mark for unload all ClassLoaderData referencing a dead class loader.
1743 bool unloading_occurred = ClassLoaderDataGraph::do_unloading(is_alive,
1744 clean_previous_versions);
1745 if (unloading_occurred) {
1746 dictionary()->do_unloading();
1747 constraints()->purge_loader_constraints();
1748 resolution_errors()->purge_resolution_errors();
1749 }
1750 // Oops referenced by the system dictionary may get unreachable independently
1751 // of the class loader (eg. cached protection domain oops). So we need to
1752 // explicitly unlink them here instead of in Dictionary::do_unloading.
1753 dictionary()->unlink(is_alive);
1754 #ifdef ASSERT
1755 VerifySDReachableAndLiveClosure cl(is_alive);
1756 dictionary()->oops_do(&cl);
1757 #endif
1758 return unloading_occurred;
1759 }
1760
1761 void SystemDictionary::roots_oops_do(OopClosure* strong, OopClosure* weak) {
1762 strong->do_oop(&_java_system_loader);
1763 strong->do_oop(&_system_loader_lock_obj);
1764 CDS_ONLY(SystemDictionaryShared::roots_oops_do(strong);)
1765
1766 // Adjust dictionary
1767 dictionary()->roots_oops_do(strong, weak);
1768
1769 // Visit extra methods
1770 invoke_method_table()->oops_do(strong);
1771 }
1772
1773 void SystemDictionary::oops_do(OopClosure* f) {
1774 f->do_oop(&_java_system_loader);
1775 f->do_oop(&_system_loader_lock_obj);
1776 CDS_ONLY(SystemDictionaryShared::oops_do(f);)
1777
1778 // Adjust dictionary
1779 dictionary()->oops_do(f);
1780
1781 // Visit extra methods
1782 invoke_method_table()->oops_do(f);
1783 }
1784
1785 // Extended Class redefinition support.
1786 // If one of these classes is replaced, we need to replace it in these places.
1787 // KlassClosure::do_klass should take the address of a class but we can
1788 // change that later.
1789 void SystemDictionary::preloaded_classes_do(KlassClosure* f) {
1790 for (int k = (int)FIRST_WKID; k < (int)WKID_LIMIT; k++) {
1791 f->do_klass(_well_known_klasses[k]);
1792 }
1793
1794 {
1795 for (int i = 0; i < T_VOID+1; i++) {
1796 if (_box_klasses[i] != NULL) {
1797 assert(i >= T_BOOLEAN, "checking");
1798 f->do_klass(_box_klasses[i]);
1799 }
1800 }
1801 }
1802
1803 FilteredFieldsMap::classes_do(f);
1804 }
1805
1806 void SystemDictionary::lazily_loaded_classes_do(KlassClosure* f) {
1807 f->do_klass(_abstract_ownable_synchronizer_klass);
1808 }
1809
1810 // Just the classes from defining class loaders
1811 // Don't iterate over placeholders
1812 void SystemDictionary::classes_do(void f(Klass*)) {
1813 dictionary()->classes_do(f);
1814 }
1815
1816 // Added for initialize_itable_for_klass
1817 // Just the classes from defining class loaders
1818 // Don't iterate over placeholders
1819 void SystemDictionary::classes_do(void f(Klass*, TRAPS), TRAPS) {
1820 dictionary()->classes_do(f, CHECK);
1821 }
1822
1823 // All classes, and their class loaders
1824 // Don't iterate over placeholders
1825 void SystemDictionary::classes_do(void f(Klass*, ClassLoaderData*)) {
1826 dictionary()->classes_do(f);
1827 }
1828
1829 void SystemDictionary::placeholders_do(void f(Symbol*)) {
1830 placeholders()->entries_do(f);
1831 }
1832
1833 void SystemDictionary::methods_do(void f(Method*)) {
1834 dictionary()->methods_do(f);
1835 invoke_method_table()->methods_do(f);
1836 }
1837
1838 void SystemDictionary::remove_classes_in_error_state() {
1839 dictionary()->remove_classes_in_error_state();
1840 }
1841
1842 // ----------------------------------------------------------------------------
1843 // Lazily load klasses
1844
1845 void SystemDictionary::load_abstract_ownable_synchronizer_klass(TRAPS) {
1846 // if multiple threads calling this function, only one thread will load
1847 // the class. The other threads will find the loaded version once the
1848 // class is loaded.
1849 Klass* aos = _abstract_ownable_synchronizer_klass;
1850 if (aos == NULL) {
1851 Klass* k = resolve_or_fail(vmSymbols::java_util_concurrent_locks_AbstractOwnableSynchronizer(), true, CHECK);
1852 // Force a fence to prevent any read before the write completes
1853 OrderAccess::fence();
1854 _abstract_ownable_synchronizer_klass = InstanceKlass::cast(k);
1855 }
1856 }
1857
1858 // ----------------------------------------------------------------------------
1859 // Initialization
1860
1861 void SystemDictionary::initialize(TRAPS) {
1862 // Allocate arrays
1863 assert(dictionary() == NULL,
1864 "SystemDictionary should only be initialized once");
1865 _sdgeneration = 0;
1866 _dictionary = new Dictionary(calculate_systemdictionary_size(PredictedLoadedClassCount));
1867 _placeholders = new PlaceholderTable(_nof_buckets);
1868 _number_of_modifications = 0;
1869 _loader_constraints = new LoaderConstraintTable(_loader_constraint_size);
1870 _resolution_errors = new ResolutionErrorTable(_resolution_error_size);
1871 _invoke_method_table = new SymbolPropertyTable(_invoke_method_size);
1872
1873 // Allocate private object used as system class loader lock
1874 _system_loader_lock_obj = oopFactory::new_intArray(0, CHECK);
1875 // Initialize basic classes
1876 initialize_preloaded_classes(CHECK);
1877 }
1878
1879 // Compact table of directions on the initialization of klasses:
1880 static const short wk_init_info[] = {
1881 #define WK_KLASS_INIT_INFO(name, symbol, option) \
1882 ( ((int)vmSymbols::VM_SYMBOL_ENUM_NAME(symbol) \
1883 << SystemDictionary::CEIL_LG_OPTION_LIMIT) \
1884 | (int)SystemDictionary::option ),
1885 WK_KLASSES_DO(WK_KLASS_INIT_INFO)
1886 #undef WK_KLASS_INIT_INFO
1887 0
1888 };
1889
1890 bool SystemDictionary::initialize_wk_klass(WKID id, int init_opt, TRAPS) {
1891 assert(id >= (int)FIRST_WKID && id < (int)WKID_LIMIT, "oob");
1892 int info = wk_init_info[id - FIRST_WKID];
1893 int sid = (info >> CEIL_LG_OPTION_LIMIT);
1894 Symbol* symbol = vmSymbols::symbol_at((vmSymbols::SID)sid);
1895 InstanceKlass** klassp = &_well_known_klasses[id];
1896 bool must_load = (init_opt < SystemDictionary::Opt);
1897 if ((*klassp) == NULL) {
1898 Klass* k;
1899 if (must_load) {
1900 k = resolve_or_fail(symbol, true, CHECK_0); // load required class
1901 } else {
1902 k = resolve_or_null(symbol, CHECK_0); // load optional klass
1903 }
1904 (*klassp) = (k == NULL) ? NULL : InstanceKlass::cast(k);
1905 }
1906 return ((*klassp) != NULL);
1907 }
1908
1909 void SystemDictionary::initialize_wk_klasses_until(WKID limit_id, WKID &start_id, TRAPS) {
1910 assert((int)start_id <= (int)limit_id, "IDs are out of order!");
1911 for (int id = (int)start_id; id < (int)limit_id; id++) {
1912 assert(id >= (int)FIRST_WKID && id < (int)WKID_LIMIT, "oob");
1913 int info = wk_init_info[id - FIRST_WKID];
1914 int sid = (info >> CEIL_LG_OPTION_LIMIT);
1915 int opt = (info & right_n_bits(CEIL_LG_OPTION_LIMIT));
1916
1917 initialize_wk_klass((WKID)id, opt, CHECK);
1918 }
1919
1920 // move the starting value forward to the limit:
1921 start_id = limit_id;
1922 }
1923
1924 void SystemDictionary::initialize_preloaded_classes(TRAPS) {
1925 assert(WK_KLASS(Object_klass) == NULL, "preloaded classes should only be initialized once");
1926 // Preload commonly used klasses
1927 WKID scan = FIRST_WKID;
1928 // first do Object, then String, Class
1929 if (UseSharedSpaces) {
1930 initialize_wk_klasses_through(WK_KLASS_ENUM_NAME(Object_klass), scan, CHECK);
1931 // Initialize the constant pool for the Object_class
1932 InstanceKlass* ik = InstanceKlass::cast(Object_klass());
1933 ik->constants()->restore_unshareable_info(CHECK);
1934 initialize_wk_klasses_through(WK_KLASS_ENUM_NAME(Class_klass), scan, CHECK);
1935 } else {
1936 initialize_wk_klasses_through(WK_KLASS_ENUM_NAME(Class_klass), scan, CHECK);
1937 }
1938
1939 // Calculate offsets for String and Class classes since they are loaded and
1940 // can be used after this point.
1941 java_lang_String::compute_offsets();
1942 java_lang_Class::compute_offsets();
1943
1944 // Fixup mirrors for classes loaded before java.lang.Class.
1945 // These calls iterate over the objects currently in the perm gen
1946 // so calling them at this point is matters (not before when there
1947 // are fewer objects and not later after there are more objects
1948 // in the perm gen.
1949 Universe::initialize_basic_type_mirrors(CHECK);
1950 Universe::fixup_mirrors(CHECK);
1951
1952 // do a bunch more:
1953 initialize_wk_klasses_through(WK_KLASS_ENUM_NAME(Reference_klass), scan, CHECK);
1954
1955 // Preload ref klasses and set reference types
1956 InstanceKlass::cast(WK_KLASS(Reference_klass))->set_reference_type(REF_OTHER);
1957 InstanceRefKlass::update_nonstatic_oop_maps(WK_KLASS(Reference_klass));
1958
1959 initialize_wk_klasses_through(WK_KLASS_ENUM_NAME(Cleaner_klass), scan, CHECK);
1960 InstanceKlass::cast(WK_KLASS(SoftReference_klass))->set_reference_type(REF_SOFT);
1961 InstanceKlass::cast(WK_KLASS(WeakReference_klass))->set_reference_type(REF_WEAK);
1962 InstanceKlass::cast(WK_KLASS(FinalReference_klass))->set_reference_type(REF_FINAL);
1963 InstanceKlass::cast(WK_KLASS(PhantomReference_klass))->set_reference_type(REF_PHANTOM);
1964 InstanceKlass::cast(WK_KLASS(Cleaner_klass))->set_reference_type(REF_CLEANER);
1965
1966 // JSR 292 classes
1967 WKID jsr292_group_start = WK_KLASS_ENUM_NAME(MethodHandle_klass);
1968 WKID jsr292_group_end = WK_KLASS_ENUM_NAME(VolatileCallSite_klass);
1969 initialize_wk_klasses_until(jsr292_group_start, scan, CHECK);
1970 initialize_wk_klasses_through(jsr292_group_end, scan, CHECK);
1971 initialize_wk_klasses_until(NOT_JVMCI(WKID_LIMIT) JVMCI_ONLY(FIRST_JVMCI_WKID), scan, CHECK);
1972
1973 _box_klasses[T_BOOLEAN] = WK_KLASS(Boolean_klass);
1974 _box_klasses[T_CHAR] = WK_KLASS(Character_klass);
1975 _box_klasses[T_FLOAT] = WK_KLASS(Float_klass);
1976 _box_klasses[T_DOUBLE] = WK_KLASS(Double_klass);
1977 _box_klasses[T_BYTE] = WK_KLASS(Byte_klass);
1978 _box_klasses[T_SHORT] = WK_KLASS(Short_klass);
1979 _box_klasses[T_INT] = WK_KLASS(Integer_klass);
1980 _box_klasses[T_LONG] = WK_KLASS(Long_klass);
1981 //_box_klasses[T_OBJECT] = WK_KLASS(object_klass);
1982 //_box_klasses[T_ARRAY] = WK_KLASS(object_klass);
1983
1984 { // Compute whether we should use loadClass or loadClassInternal when loading classes.
1985 Method* method = InstanceKlass::cast(ClassLoader_klass())->find_method(vmSymbols::loadClassInternal_name(), vmSymbols::string_class_signature());
1986 _has_loadClassInternal = (method != NULL);
1987 }
1988 { // Compute whether we should use checkPackageAccess or NOT
1989 Method* method = InstanceKlass::cast(ClassLoader_klass())->find_method(vmSymbols::checkPackageAccess_name(), vmSymbols::class_protectiondomain_signature());
1990 _has_checkPackageAccess = (method != NULL);
1991 }
1992 }
1993
1994 // Tells if a given klass is a box (wrapper class, such as java.lang.Integer).
1995 // If so, returns the basic type it holds. If not, returns T_OBJECT.
1996 BasicType SystemDictionary::box_klass_type(Klass* k) {
1997 assert(k != NULL, "");
1998 for (int i = T_BOOLEAN; i < T_VOID+1; i++) {
1999 if (_box_klasses[i] == k)
2000 return (BasicType)i;
2001 }
2002 return T_OBJECT;
2003 }
2004
2005 // Constraints on class loaders. The details of the algorithm can be
2006 // found in the OOPSLA'98 paper "Dynamic Class Loading in the Java
2007 // Virtual Machine" by Sheng Liang and Gilad Bracha. The basic idea is
2008 // that the system dictionary needs to maintain a set of contraints that
2009 // must be satisfied by all classes in the dictionary.
2010 // if defining is true, then LinkageError if already in systemDictionary
2011 // if initiating loader, then ok if InstanceKlass matches existing entry
2012
2013 void SystemDictionary::check_constraints(int d_index, unsigned int d_hash,
2014 instanceKlassHandle k,
2015 Handle class_loader, bool defining,
2016 TRAPS) {
2017 const char *linkage_error1 = NULL;
2018 const char *linkage_error2 = NULL;
2019 {
2020 Symbol* name = k->name();
2021 ClassLoaderData *loader_data = class_loader_data(class_loader);
2022
2023 MutexLocker mu(SystemDictionary_lock, THREAD);
2024
2025 Klass* check = find_class(d_index, d_hash, name, loader_data);
2026 if (check != (Klass*)NULL) {
2027 // if different InstanceKlass - duplicate class definition,
2028 // else - ok, class loaded by a different thread in parallel,
2029 // we should only have found it if it was done loading and ok to use
2030 // system dictionary only holds instance classes, placeholders
2031 // also holds array classes
2032
2033 assert(check->is_instance_klass(), "noninstance in systemdictionary");
2034 if ((defining == true) || (k() != check)) {
2035 linkage_error1 = "loader (instance of ";
2036 linkage_error2 = "): attempted duplicate class definition for name: \"";
2037 } else {
2038 return;
2039 }
2040 }
2041
2042 #ifdef ASSERT
2043 Symbol* ph_check = find_placeholder(name, loader_data);
2044 assert(ph_check == NULL || ph_check == name, "invalid symbol");
2045 #endif
2046
2047 if (linkage_error1 == NULL) {
2048 if (constraints()->check_or_update(k, class_loader, name) == false) {
2049 linkage_error1 = "loader constraint violation: loader (instance of ";
2050 linkage_error2 = ") previously initiated loading for a different type with name \"";
2051 }
2052 }
2053 }
2054
2055 // Throw error now if needed (cannot throw while holding
2056 // SystemDictionary_lock because of rank ordering)
2057
2058 if (linkage_error1) {
2059 ResourceMark rm(THREAD);
2060 const char* class_loader_name = loader_name(class_loader());
2061 char* type_name = k->name()->as_C_string();
2062 size_t buflen = strlen(linkage_error1) + strlen(class_loader_name) +
2063 strlen(linkage_error2) + strlen(type_name) + 2; // +2 for '"' and null byte.
2064 char* buf = NEW_RESOURCE_ARRAY_IN_THREAD(THREAD, char, buflen);
2065 jio_snprintf(buf, buflen, "%s%s%s%s\"", linkage_error1, class_loader_name, linkage_error2, type_name);
2066 THROW_MSG(vmSymbols::java_lang_LinkageError(), buf);
2067 }
2068 }
2069
2070
2071 // Update system dictionary - done after check_constraint and add_to_hierachy
2072 // have been called.
2073 void SystemDictionary::update_dictionary(int d_index, unsigned int d_hash,
2074 int p_index, unsigned int p_hash,
2075 instanceKlassHandle k,
2076 Handle class_loader,
2077 TRAPS) {
2078 // Compile_lock prevents systemDictionary updates during compilations
2079 assert_locked_or_safepoint(Compile_lock);
2080 Symbol* name = k->name();
2081 ClassLoaderData *loader_data = class_loader_data(class_loader);
2082
2083 {
2084 MutexLocker mu1(SystemDictionary_lock, THREAD);
2085
2086 // See whether biased locking is enabled and if so set it for this
2087 // klass.
2088 // Note that this must be done past the last potential blocking
2089 // point / safepoint. We enable biased locking lazily using a
2090 // VM_Operation to iterate the SystemDictionary and installing the
2091 // biasable mark word into each InstanceKlass's prototype header.
2092 // To avoid race conditions where we accidentally miss enabling the
2093 // optimization for one class in the process of being added to the
2094 // dictionary, we must not safepoint after the test of
2095 // BiasedLocking::enabled().
2096 if (UseBiasedLocking && BiasedLocking::enabled()) {
2097 // Set biased locking bit for all loaded classes; it will be
2098 // cleared if revocation occurs too often for this type
2099 // NOTE that we must only do this when the class is initally
2100 // defined, not each time it is referenced from a new class loader
2101 if (k->class_loader() == class_loader()) {
2102 k->set_prototype_header(markOopDesc::biased_locking_prototype());
2103 }
2104 }
2105
2106 // Make a new system dictionary entry.
2107 Klass* sd_check = find_class(d_index, d_hash, name, loader_data);
2108 if (sd_check == NULL) {
2109 dictionary()->add_klass(name, loader_data, k);
2110 notice_modification();
2111 }
2112 #ifdef ASSERT
2113 sd_check = find_class(d_index, d_hash, name, loader_data);
2114 assert (sd_check != NULL, "should have entry in system dictionary");
2115 // Note: there may be a placeholder entry: for circularity testing
2116 // or for parallel defines
2117 #endif
2118 SystemDictionary_lock->notify_all();
2119 }
2120 }
2121
2122
2123 // Try to find a class name using the loader constraints. The
2124 // loader constraints might know about a class that isn't fully loaded
2125 // yet and these will be ignored.
2126 Klass* SystemDictionary::find_constrained_instance_or_array_klass(
2127 Symbol* class_name, Handle class_loader, TRAPS) {
2128
2129 // First see if it has been loaded directly.
2130 // Force the protection domain to be null. (This removes protection checks.)
2131 Handle no_protection_domain;
2132 Klass* klass = find_instance_or_array_klass(class_name, class_loader,
2133 no_protection_domain, CHECK_NULL);
2134 if (klass != NULL)
2135 return klass;
2136
2137 // Now look to see if it has been loaded elsewhere, and is subject to
2138 // a loader constraint that would require this loader to return the
2139 // klass that is already loaded.
2140 if (FieldType::is_array(class_name)) {
2141 // For array classes, their Klass*s are not kept in the
2142 // constraint table. The element Klass*s are.
2143 FieldArrayInfo fd;
2144 BasicType t = FieldType::get_array_info(class_name, fd, CHECK_(NULL));
2145 if (t != T_OBJECT) {
2146 klass = Universe::typeArrayKlassObj(t);
2147 } else {
2148 MutexLocker mu(SystemDictionary_lock, THREAD);
2149 klass = constraints()->find_constrained_klass(fd.object_key(), class_loader);
2150 }
2151 // If element class already loaded, allocate array klass
2152 if (klass != NULL) {
2153 klass = klass->array_klass_or_null(fd.dimension());
2154 }
2155 } else {
2156 MutexLocker mu(SystemDictionary_lock, THREAD);
2157 // Non-array classes are easy: simply check the constraint table.
2158 klass = constraints()->find_constrained_klass(class_name, class_loader);
2159 }
2160
2161 return klass;
2162 }
2163
2164
2165 bool SystemDictionary::add_loader_constraint(Symbol* class_name,
2166 Handle class_loader1,
2167 Handle class_loader2,
2168 Thread* THREAD) {
2169 ClassLoaderData* loader_data1 = class_loader_data(class_loader1);
2170 ClassLoaderData* loader_data2 = class_loader_data(class_loader2);
2171
2172 Symbol* constraint_name = NULL;
2173 if (!FieldType::is_array(class_name)) {
2174 constraint_name = class_name;
2175 } else {
2176 // For array classes, their Klass*s are not kept in the
2177 // constraint table. The element classes are.
2178 FieldArrayInfo fd;
2179 BasicType t = FieldType::get_array_info(class_name, fd, CHECK_(false));
2180 // primitive types always pass
2181 if (t != T_OBJECT) {
2182 return true;
2183 } else {
2184 constraint_name = fd.object_key();
2185 }
2186 }
2187 unsigned int d_hash1 = dictionary()->compute_hash(constraint_name, loader_data1);
2188 int d_index1 = dictionary()->hash_to_index(d_hash1);
2189
2190 unsigned int d_hash2 = dictionary()->compute_hash(constraint_name, loader_data2);
2191 int d_index2 = dictionary()->hash_to_index(d_hash2);
2192 {
2193 MutexLocker mu_s(SystemDictionary_lock, THREAD);
2194
2195 // Better never do a GC while we're holding these oops
2196 No_Safepoint_Verifier nosafepoint;
2197
2198 Klass* klass1 = find_class(d_index1, d_hash1, constraint_name, loader_data1);
2199 Klass* klass2 = find_class(d_index2, d_hash2, constraint_name, loader_data2);
2200 return constraints()->add_entry(constraint_name, klass1, class_loader1,
2201 klass2, class_loader2);
2202 }
2203 }
2204
2205 // Add entry to resolution error table to record the error when the first
2206 // attempt to resolve a reference to a class has failed.
2207 void SystemDictionary::add_resolution_error(const constantPoolHandle& pool, int which,
2208 Symbol* error, Symbol* message) {
2209 unsigned int hash = resolution_errors()->compute_hash(pool, which);
2210 int index = resolution_errors()->hash_to_index(hash);
2211 {
2212 MutexLocker ml(SystemDictionary_lock, Thread::current());
2213 resolution_errors()->add_entry(index, hash, pool, which, error, message);
2214 }
2215 }
2216
2217 // Delete a resolution error for RedefineClasses for a constant pool is going away
2218 void SystemDictionary::delete_resolution_error(ConstantPool* pool) {
2219 resolution_errors()->delete_entry(pool);
2220 }
2221
2222 // Lookup resolution error table. Returns error if found, otherwise NULL.
2223 Symbol* SystemDictionary::find_resolution_error(const constantPoolHandle& pool, int which,
2224 Symbol** message) {
2225 unsigned int hash = resolution_errors()->compute_hash(pool, which);
2226 int index = resolution_errors()->hash_to_index(hash);
2227 {
2228 MutexLocker ml(SystemDictionary_lock, Thread::current());
2229 ResolutionErrorEntry* entry = resolution_errors()->find_entry(index, hash, pool, which);
2230 if (entry != NULL) {
2231 *message = entry->message();
2232 return entry->error();
2233 } else {
2234 return NULL;
2235 }
2236 }
2237 }
2238
2239
2240 // Signature constraints ensure that callers and callees agree about
2241 // the meaning of type names in their signatures. This routine is the
2242 // intake for constraints. It collects them from several places:
2243 //
2244 // * LinkResolver::resolve_method (if check_access is true) requires
2245 // that the resolving class (the caller) and the defining class of
2246 // the resolved method (the callee) agree on each type in the
2247 // method's signature.
2248 //
2249 // * LinkResolver::resolve_interface_method performs exactly the same
2250 // checks.
2251 //
2252 // * LinkResolver::resolve_field requires that the constant pool
2253 // attempting to link to a field agree with the field's defining
2254 // class about the type of the field signature.
2255 //
2256 // * klassVtable::initialize_vtable requires that, when a class
2257 // overrides a vtable entry allocated by a superclass, that the
2258 // overriding method (i.e., the callee) agree with the superclass
2259 // on each type in the method's signature.
2260 //
2261 // * klassItable::initialize_itable requires that, when a class fills
2262 // in its itables, for each non-abstract method installed in an
2263 // itable, the method (i.e., the callee) agree with the interface
2264 // on each type in the method's signature.
2265 //
2266 // All those methods have a boolean (check_access, checkconstraints)
2267 // which turns off the checks. This is used from specialized contexts
2268 // such as bootstrapping, dumping, and debugging.
2269 //
2270 // No direct constraint is placed between the class and its
2271 // supertypes. Constraints are only placed along linked relations
2272 // between callers and callees. When a method overrides or implements
2273 // an abstract method in a supertype (superclass or interface), the
2274 // constraints are placed as if the supertype were the caller to the
2275 // overriding method. (This works well, since callers to the
2276 // supertype have already established agreement between themselves and
2277 // the supertype.) As a result of all this, a class can disagree with
2278 // its supertype about the meaning of a type name, as long as that
2279 // class neither calls a relevant method of the supertype, nor is
2280 // called (perhaps via an override) from the supertype.
2281 //
2282 //
2283 // SystemDictionary::check_signature_loaders(sig, l1, l2)
2284 //
2285 // Make sure all class components (including arrays) in the given
2286 // signature will be resolved to the same class in both loaders.
2287 // Returns the name of the type that failed a loader constraint check, or
2288 // NULL if no constraint failed. No exception except OOME is thrown.
2289 // Arrays are not added to the loader constraint table, their elements are.
2290 Symbol* SystemDictionary::check_signature_loaders(Symbol* signature,
2291 Handle loader1, Handle loader2,
2292 bool is_method, TRAPS) {
2293 // Nothing to do if loaders are the same.
2294 if (loader1() == loader2()) {
2295 return NULL;
2296 }
2297
2298 SignatureStream sig_strm(signature, is_method);
2299 while (!sig_strm.is_done()) {
2300 if (sig_strm.is_object()) {
2301 Symbol* sig = sig_strm.as_symbol(CHECK_NULL);
2302 if (!add_loader_constraint(sig, loader1, loader2, THREAD)) {
2303 return sig;
2304 }
2305 }
2306 sig_strm.next();
2307 }
2308 return NULL;
2309 }
2310
2311
2312 methodHandle SystemDictionary::find_method_handle_intrinsic(vmIntrinsics::ID iid,
2313 Symbol* signature,
2314 TRAPS) {
2315 methodHandle empty;
2316 assert(MethodHandles::is_signature_polymorphic(iid) &&
2317 MethodHandles::is_signature_polymorphic_intrinsic(iid) &&
2318 iid != vmIntrinsics::_invokeGeneric,
2319 "must be a known MH intrinsic iid=%d: %s", iid, vmIntrinsics::name_at(iid));
2320
2321 unsigned int hash = invoke_method_table()->compute_hash(signature, iid);
2322 int index = invoke_method_table()->hash_to_index(hash);
2323 SymbolPropertyEntry* spe = invoke_method_table()->find_entry(index, hash, signature, iid);
2324 methodHandle m;
2325 if (spe == NULL || spe->method() == NULL) {
2326 spe = NULL;
2327 // Must create lots of stuff here, but outside of the SystemDictionary lock.
2328 m = Method::make_method_handle_intrinsic(iid, signature, CHECK_(empty));
2329 if (!Arguments::is_interpreter_only()) {
2330 // Generate a compiled form of the MH intrinsic.
2331 AdapterHandlerLibrary::create_native_wrapper(m);
2332 // Check if have the compiled code.
2333 if (!m->has_compiled_code()) {
2334 THROW_MSG_(vmSymbols::java_lang_VirtualMachineError(),
2335 "out of space in CodeCache for method handle intrinsic", empty);
2336 }
2337 }
2338 // Now grab the lock. We might have to throw away the new method,
2339 // if a racing thread has managed to install one at the same time.
2340 {
2341 MutexLocker ml(SystemDictionary_lock, THREAD);
2342 spe = invoke_method_table()->find_entry(index, hash, signature, iid);
2343 if (spe == NULL)
2344 spe = invoke_method_table()->add_entry(index, hash, signature, iid);
2345 if (spe->method() == NULL)
2346 spe->set_method(m());
2347 }
2348 }
2349
2350 assert(spe != NULL && spe->method() != NULL, "");
2351 assert(Arguments::is_interpreter_only() || (spe->method()->has_compiled_code() &&
2352 spe->method()->code()->entry_point() == spe->method()->from_compiled_entry()),
2353 "MH intrinsic invariant");
2354 return spe->method();
2355 }
2356
2357 // Helper for unpacking the return value from linkMethod and linkCallSite.
2358 static methodHandle unpack_method_and_appendix(Handle mname,
2359 KlassHandle accessing_klass,
2360 objArrayHandle appendix_box,
2361 Handle* appendix_result,
2362 TRAPS) {
2363 methodHandle empty;
2364 if (mname.not_null()) {
2365 Metadata* vmtarget = java_lang_invoke_MemberName::vmtarget(mname());
2366 if (vmtarget != NULL && vmtarget->is_method()) {
2367 Method* m = (Method*)vmtarget;
2368 oop appendix = appendix_box->obj_at(0);
2369 if (TraceMethodHandles) {
2370 #ifndef PRODUCT
2371 tty->print("Linked method=" INTPTR_FORMAT ": ", p2i(m));
2372 m->print();
2373 if (appendix != NULL) { tty->print("appendix = "); appendix->print(); }
2374 tty->cr();
2375 #endif //PRODUCT
2376 }
2377 (*appendix_result) = Handle(THREAD, appendix);
2378 // the target is stored in the cpCache and if a reference to this
2379 // MethodName is dropped we need a way to make sure the
2380 // class_loader containing this method is kept alive.
2381 // FIXME: the appendix might also preserve this dependency.
2382 ClassLoaderData* this_key = InstanceKlass::cast(accessing_klass())->class_loader_data();
2383 this_key->record_dependency(m->method_holder(), CHECK_NULL); // Can throw OOM
2384 return methodHandle(THREAD, m);
2385 }
2386 }
2387 THROW_MSG_(vmSymbols::java_lang_LinkageError(), "bad value from MethodHandleNatives", empty);
2388 return empty;
2389 }
2390
2391 methodHandle SystemDictionary::find_method_handle_invoker(Symbol* name,
2392 Symbol* signature,
2393 KlassHandle accessing_klass,
2394 Handle *appendix_result,
2395 Handle *method_type_result,
2396 TRAPS) {
2397 methodHandle empty;
2398 assert(THREAD->can_call_java() ,"");
2399 Handle method_type =
2400 SystemDictionary::find_method_handle_type(signature, accessing_klass, CHECK_(empty));
2401
2402 KlassHandle mh_klass = SystemDictionary::MethodHandle_klass();
2403 int ref_kind = JVM_REF_invokeVirtual;
2404 Handle name_str = StringTable::intern(name, CHECK_(empty));
2405 objArrayHandle appendix_box = oopFactory::new_objArray(SystemDictionary::Object_klass(), 1, CHECK_(empty));
2406 assert(appendix_box->obj_at(0) == NULL, "");
2407
2408 // This should not happen. JDK code should take care of that.
2409 if (accessing_klass.is_null() || method_type.is_null()) {
2410 THROW_MSG_(vmSymbols::java_lang_InternalError(), "bad invokehandle", empty);
2411 }
2412
2413 // call java.lang.invoke.MethodHandleNatives::linkMethod(... String, MethodType) -> MemberName
2414 JavaCallArguments args;
2415 args.push_oop(accessing_klass()->java_mirror());
2416 args.push_int(ref_kind);
2417 args.push_oop(mh_klass()->java_mirror());
2418 args.push_oop(name_str());
2419 args.push_oop(method_type());
2420 args.push_oop(appendix_box());
2421 JavaValue result(T_OBJECT);
2422 JavaCalls::call_static(&result,
2423 SystemDictionary::MethodHandleNatives_klass(),
2424 vmSymbols::linkMethod_name(),
2425 vmSymbols::linkMethod_signature(),
2426 &args, CHECK_(empty));
2427 Handle mname(THREAD, (oop) result.get_jobject());
2428 (*method_type_result) = method_type;
2429 return unpack_method_and_appendix(mname, accessing_klass, appendix_box, appendix_result, THREAD);
2430 }
2431
2432 // Decide if we can globally cache a lookup of this class, to be returned to any client that asks.
2433 // We must ensure that all class loaders everywhere will reach this class, for any client.
2434 // This is a safe bet for public classes in java.lang, such as Object and String.
2435 // We also include public classes in java.lang.invoke, because they appear frequently in system-level method types.
2436 // Out of an abundance of caution, we do not include any other classes, not even for packages like java.util.
2437 static bool is_always_visible_class(oop mirror) {
2438 Klass* klass = java_lang_Class::as_Klass(mirror);
2439 if (klass->is_objArray_klass()) {
2440 klass = ObjArrayKlass::cast(klass)->bottom_klass(); // check element type
2441 }
2442 if (klass->is_typeArray_klass()) {
2443 return true; // primitive array
2444 }
2445 assert(klass->is_instance_klass(), "%s", klass->external_name());
2446 return klass->is_public() &&
2447 (InstanceKlass::cast(klass)->is_same_class_package(SystemDictionary::Object_klass()) || // java.lang
2448 InstanceKlass::cast(klass)->is_same_class_package(SystemDictionary::MethodHandle_klass())); // java.lang.invoke
2449 }
2450
2451 // Ask Java code to find or construct a java.lang.invoke.MethodType for the given
2452 // signature, as interpreted relative to the given class loader.
2453 // Because of class loader constraints, all method handle usage must be
2454 // consistent with this loader.
2455 Handle SystemDictionary::find_method_handle_type(Symbol* signature,
2456 KlassHandle accessing_klass,
2457 TRAPS) {
2458 Handle empty;
2459 vmIntrinsics::ID null_iid = vmIntrinsics::_none; // distinct from all method handle invoker intrinsics
2460 unsigned int hash = invoke_method_table()->compute_hash(signature, null_iid);
2461 int index = invoke_method_table()->hash_to_index(hash);
2462 SymbolPropertyEntry* spe = invoke_method_table()->find_entry(index, hash, signature, null_iid);
2463 if (spe != NULL && spe->method_type() != NULL) {
2464 assert(java_lang_invoke_MethodType::is_instance(spe->method_type()), "");
2465 return Handle(THREAD, spe->method_type());
2466 } else if (!THREAD->can_call_java()) {
2467 warning("SystemDictionary::find_method_handle_type called from compiler thread"); // FIXME
2468 return Handle(); // do not attempt from within compiler, unless it was cached
2469 }
2470
2471 Handle class_loader, protection_domain;
2472 if (accessing_klass.not_null()) {
2473 class_loader = Handle(THREAD, InstanceKlass::cast(accessing_klass())->class_loader());
2474 protection_domain = Handle(THREAD, InstanceKlass::cast(accessing_klass())->protection_domain());
2475 }
2476 bool can_be_cached = true;
2477 int npts = ArgumentCount(signature).size();
2478 objArrayHandle pts = oopFactory::new_objArray(SystemDictionary::Class_klass(), npts, CHECK_(empty));
2479 int arg = 0;
2480 Handle rt; // the return type from the signature
2481 ResourceMark rm(THREAD);
2482 for (SignatureStream ss(signature); !ss.is_done(); ss.next()) {
2483 oop mirror = NULL;
2484 if (can_be_cached) {
2485 // Use neutral class loader to lookup candidate classes to be placed in the cache.
2486 mirror = ss.as_java_mirror(Handle(), Handle(),
2487 SignatureStream::ReturnNull, CHECK_(empty));
2488 if (mirror == NULL || (ss.is_object() && !is_always_visible_class(mirror))) {
2489 // Fall back to accessing_klass context.
2490 can_be_cached = false;
2491 }
2492 }
2493 if (!can_be_cached) {
2494 // Resolve, throwing a real error if it doesn't work.
2495 mirror = ss.as_java_mirror(class_loader, protection_domain,
2496 SignatureStream::NCDFError, CHECK_(empty));
2497 }
2498 assert(!oopDesc::is_null(mirror), "%s", ss.as_symbol(THREAD)->as_C_string());
2499 if (ss.at_return_type())
2500 rt = Handle(THREAD, mirror);
2501 else
2502 pts->obj_at_put(arg++, mirror);
2503
2504 // Check accessibility.
2505 if (ss.is_object() && accessing_klass.not_null()) {
2506 Klass* sel_klass = java_lang_Class::as_Klass(mirror);
2507 mirror = NULL; // safety
2508 // Emulate ConstantPool::verify_constant_pool_resolve.
2509 if (sel_klass->is_objArray_klass())
2510 sel_klass = ObjArrayKlass::cast(sel_klass)->bottom_klass();
2511 if (sel_klass->is_instance_klass()) {
2512 KlassHandle sel_kh(THREAD, sel_klass);
2513 LinkResolver::check_klass_accessability(accessing_klass, sel_kh, CHECK_(empty));
2514 }
2515 }
2516 }
2517 assert(arg == npts, "");
2518
2519 // call java.lang.invoke.MethodHandleNatives::findMethodType(Class rt, Class[] pts) -> MethodType
2520 JavaCallArguments args(Handle(THREAD, rt()));
2521 args.push_oop(pts());
2522 JavaValue result(T_OBJECT);
2523 JavaCalls::call_static(&result,
2524 SystemDictionary::MethodHandleNatives_klass(),
2525 vmSymbols::findMethodHandleType_name(),
2526 vmSymbols::findMethodHandleType_signature(),
2527 &args, CHECK_(empty));
2528 Handle method_type(THREAD, (oop) result.get_jobject());
2529
2530 if (can_be_cached) {
2531 // We can cache this MethodType inside the JVM.
2532 MutexLocker ml(SystemDictionary_lock, THREAD);
2533 spe = invoke_method_table()->find_entry(index, hash, signature, null_iid);
2534 if (spe == NULL)
2535 spe = invoke_method_table()->add_entry(index, hash, signature, null_iid);
2536 if (spe->method_type() == NULL) {
2537 spe->set_method_type(method_type());
2538 }
2539 }
2540
2541 // report back to the caller with the MethodType
2542 return method_type;
2543 }
2544
2545 // Ask Java code to find or construct a method handle constant.
2546 Handle SystemDictionary::link_method_handle_constant(KlassHandle caller,
2547 int ref_kind, //e.g., JVM_REF_invokeVirtual
2548 KlassHandle callee,
2549 Symbol* name_sym,
2550 Symbol* signature,
2551 TRAPS) {
2552 Handle empty;
2553 Handle name = java_lang_String::create_from_symbol(name_sym, CHECK_(empty));
2554 Handle type;
2555 if (signature->utf8_length() > 0 && signature->byte_at(0) == '(') {
2556 type = find_method_handle_type(signature, caller, CHECK_(empty));
2557 } else if (caller.is_null()) {
2558 // This should not happen. JDK code should take care of that.
2559 THROW_MSG_(vmSymbols::java_lang_InternalError(), "bad MH constant", empty);
2560 } else {
2561 ResourceMark rm(THREAD);
2562 SignatureStream ss(signature, false);
2563 if (!ss.is_done()) {
2564 oop mirror = ss.as_java_mirror(caller->class_loader(), caller->protection_domain(),
2565 SignatureStream::NCDFError, CHECK_(empty));
2566 type = Handle(THREAD, mirror);
2567 ss.next();
2568 if (!ss.is_done()) type = Handle(); // error!
2569 }
2570 }
2571 if (type.is_null()) {
2572 THROW_MSG_(vmSymbols::java_lang_LinkageError(), "bad signature", empty);
2573 }
2574
2575 // call java.lang.invoke.MethodHandleNatives::linkMethodHandleConstant(Class caller, int refKind, Class callee, String name, Object type) -> MethodHandle
2576 JavaCallArguments args;
2577 args.push_oop(caller->java_mirror()); // the referring class
2578 args.push_int(ref_kind);
2579 args.push_oop(callee->java_mirror()); // the target class
2580 args.push_oop(name());
2581 args.push_oop(type());
2582 JavaValue result(T_OBJECT);
2583 JavaCalls::call_static(&result,
2584 SystemDictionary::MethodHandleNatives_klass(),
2585 vmSymbols::linkMethodHandleConstant_name(),
2586 vmSymbols::linkMethodHandleConstant_signature(),
2587 &args, CHECK_(empty));
2588 return Handle(THREAD, (oop) result.get_jobject());
2589 }
2590
2591 // Ask Java code to find or construct a java.lang.invoke.CallSite for the given
2592 // name and signature, as interpreted relative to the given class loader.
2593 methodHandle SystemDictionary::find_dynamic_call_site_invoker(KlassHandle caller,
2594 Handle bootstrap_specifier,
2595 Symbol* name,
2596 Symbol* type,
2597 Handle *appendix_result,
2598 Handle *method_type_result,
2599 TRAPS) {
2600 methodHandle empty;
2601 Handle bsm, info;
2602 if (java_lang_invoke_MethodHandle::is_instance(bootstrap_specifier())) {
2603 bsm = bootstrap_specifier;
2604 } else {
2605 assert(bootstrap_specifier->is_objArray(), "");
2606 objArrayHandle args(THREAD, (objArrayOop) bootstrap_specifier());
2607 int len = args->length();
2608 assert(len >= 1, "");
2609 bsm = Handle(THREAD, args->obj_at(0));
2610 if (len > 1) {
2611 objArrayOop args1 = oopFactory::new_objArray(SystemDictionary::Object_klass(), len-1, CHECK_(empty));
2612 for (int i = 1; i < len; i++)
2613 args1->obj_at_put(i-1, args->obj_at(i));
2614 info = Handle(THREAD, args1);
2615 }
2616 }
2617 guarantee(java_lang_invoke_MethodHandle::is_instance(bsm()),
2618 "caller must supply a valid BSM");
2619
2620 Handle method_name = java_lang_String::create_from_symbol(name, CHECK_(empty));
2621 Handle method_type = find_method_handle_type(type, caller, CHECK_(empty));
2622
2623 // This should not happen. JDK code should take care of that.
2624 if (caller.is_null() || method_type.is_null()) {
2625 THROW_MSG_(vmSymbols::java_lang_InternalError(), "bad invokedynamic", empty);
2626 }
2627
2628 objArrayHandle appendix_box = oopFactory::new_objArray(SystemDictionary::Object_klass(), 1, CHECK_(empty));
2629 assert(appendix_box->obj_at(0) == NULL, "");
2630
2631 // call java.lang.invoke.MethodHandleNatives::linkCallSite(caller, bsm, name, mtype, info, &appendix)
2632 JavaCallArguments args;
2633 args.push_oop(caller->java_mirror());
2634 args.push_oop(bsm());
2635 args.push_oop(method_name());
2636 args.push_oop(method_type());
2637 args.push_oop(info());
2638 args.push_oop(appendix_box);
2639 JavaValue result(T_OBJECT);
2640 JavaCalls::call_static(&result,
2641 SystemDictionary::MethodHandleNatives_klass(),
2642 vmSymbols::linkCallSite_name(),
2643 vmSymbols::linkCallSite_signature(),
2644 &args, CHECK_(empty));
2645 Handle mname(THREAD, (oop) result.get_jobject());
2646 (*method_type_result) = method_type;
2647 return unpack_method_and_appendix(mname, caller, appendix_box, appendix_result, THREAD);
2648 }
2649
2650 // Since the identity hash code for symbols changes when the symbols are
2651 // moved from the regular perm gen (hash in the mark word) to the shared
2652 // spaces (hash is the address), the classes loaded into the dictionary
2653 // may be in the wrong buckets.
2654
2655 void SystemDictionary::reorder_dictionary() {
2656 dictionary()->reorder_dictionary();
2657 }
2658
2659
2660 void SystemDictionary::copy_buckets(char** top, char* end) {
2661 dictionary()->copy_buckets(top, end);
2662 }
2663
2664
2665 void SystemDictionary::copy_table(char** top, char* end) {
2666 dictionary()->copy_table(top, end);
2667 }
2668
2669
2670 void SystemDictionary::reverse() {
2671 dictionary()->reverse();
2672 }
2673
2674 int SystemDictionary::number_of_classes() {
2675 return dictionary()->number_of_entries();
2676 }
2677
2678
2679 // ----------------------------------------------------------------------------
2680 void SystemDictionary::print_shared(bool details) {
2681 shared_dictionary()->print(details);
2682 }
2683
2684 void SystemDictionary::print(bool details) {
2685 dictionary()->print(details);
2686
2687 // Placeholders
2688 GCMutexLocker mu(SystemDictionary_lock);
2689 placeholders()->print();
2690
2691 // loader constraints - print under SD_lock
2692 constraints()->print();
2693 }
2694
2695
2696 void SystemDictionary::verify() {
2697 guarantee(dictionary() != NULL, "Verify of system dictionary failed");
2698 guarantee(constraints() != NULL,
2699 "Verify of loader constraints failed");
2700 guarantee(dictionary()->number_of_entries() >= 0 &&
2701 placeholders()->number_of_entries() >= 0,
2702 "Verify of system dictionary failed");
2703
2704 // Verify dictionary
2705 dictionary()->verify();
2706
2707 GCMutexLocker mu(SystemDictionary_lock);
2708 placeholders()->verify();
2709
2710 // Verify constraint table
2711 guarantee(constraints() != NULL, "Verify of loader constraints failed");
2712 constraints()->verify(dictionary(), placeholders());
2713 }
2714
2715 // utility function for class load event
2716 void SystemDictionary::post_class_load_event(const Ticks& start_time,
2717 instanceKlassHandle k,
2718 Handle initiating_loader) {
2719 #if INCLUDE_TRACE
2720 EventClassLoad event(UNTIMED);
2721 if (event.should_commit()) {
2722 event.set_starttime(start_time);
2723 event.set_loadedClass(k());
2724 oop defining_class_loader = k->class_loader();
2725 event.set_definingClassLoader(defining_class_loader != NULL ?
2726 defining_class_loader->klass() : (Klass*)NULL);
2727 oop class_loader = initiating_loader.is_null() ? (oop)NULL : initiating_loader();
2728 event.set_initiatingClassLoader(class_loader != NULL ?
2729 class_loader->klass() : (Klass*)NULL);
2730 event.commit();
2731 }
2732 #endif // INCLUDE_TRACE
2733 }
2734