1 /*
   2  * Copyright (c) 1997, 2019, 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 "jvm.h"
  27 #include "aot/aotLoader.hpp"
  28 #include "classfile/classFileParser.hpp"
  29 #include "classfile/classFileStream.hpp"
  30 #include "classfile/classLoader.hpp"
  31 #include "classfile/classLoaderData.inline.hpp"
  32 #include "classfile/classLoaderDataGraph.inline.hpp"
  33 #include "classfile/classLoaderExt.hpp"
  34 #include "classfile/dictionary.hpp"
  35 #include "classfile/javaClasses.inline.hpp"
  36 #include "classfile/klassFactory.hpp"
  37 #include "classfile/loaderConstraints.hpp"
  38 #include "classfile/packageEntry.hpp"
  39 #include "classfile/placeholders.hpp"
  40 #include "classfile/protectionDomainCache.hpp"
  41 #include "classfile/resolutionErrors.hpp"
  42 #include "classfile/stringTable.hpp"
  43 #include "classfile/systemDictionary.hpp"
  44 #include "classfile/vmSymbols.hpp"
  45 #include "code/codeCache.hpp"
  46 #include "compiler/compileBroker.hpp"
  47 #include "gc/shared/gcTraceTime.inline.hpp"
  48 #include "gc/shared/oopStorage.inline.hpp"
  49 #include "interpreter/bytecodeStream.hpp"
  50 #include "interpreter/interpreter.hpp"
  51 #include "jfr/jfrEvents.hpp"
  52 #include "logging/log.hpp"
  53 #include "logging/logStream.hpp"
  54 #include "memory/filemap.hpp"
  55 #include "memory/heapShared.hpp"
  56 #include "memory/metaspaceClosure.hpp"
  57 #include "memory/oopFactory.hpp"
  58 #include "memory/resourceArea.hpp"
  59 #include "oops/access.inline.hpp"
  60 #include "oops/instanceKlass.hpp"
  61 #include "oops/instanceRefKlass.hpp"
  62 #include "oops/klass.inline.hpp"
  63 #include "oops/method.inline.hpp"
  64 #include "oops/methodData.hpp"
  65 #include "oops/objArrayKlass.hpp"
  66 #include "oops/objArrayOop.inline.hpp"
  67 #include "oops/oop.inline.hpp"
  68 #include "oops/symbol.hpp"
  69 #include "oops/typeArrayKlass.hpp"
  70 #include "prims/jvmtiExport.hpp"
  71 #include "prims/resolvedMethodTable.hpp"
  72 #include "prims/methodHandles.hpp"
  73 #include "runtime/arguments.hpp"
  74 #include "runtime/biasedLocking.hpp"
  75 #include "runtime/fieldType.hpp"
  76 #include "runtime/handles.inline.hpp"
  77 #include "runtime/java.hpp"
  78 #include "runtime/javaCalls.hpp"
  79 #include "runtime/mutexLocker.hpp"
  80 #include "runtime/orderAccess.hpp"
  81 #include "runtime/sharedRuntime.hpp"
  82 #include "runtime/signature.hpp"
  83 #include "services/classLoadingService.hpp"
  84 #include "services/diagnosticCommand.hpp"
  85 #include "services/threadService.hpp"
  86 #include "utilities/macros.hpp"
  87 #if INCLUDE_CDS
  88 #include "classfile/systemDictionaryShared.hpp"
  89 #endif
  90 #if INCLUDE_JVMCI
  91 #include "jvmci/jvmciRuntime.hpp"
  92 #endif
  93 #if INCLUDE_JFR
  94 #include "jfr/jfr.hpp"
  95 #endif
  96 
  97 PlaceholderTable*      SystemDictionary::_placeholders        = NULL;
  98 LoaderConstraintTable* SystemDictionary::_loader_constraints  = NULL;
  99 ResolutionErrorTable*  SystemDictionary::_resolution_errors   = NULL;
 100 SymbolPropertyTable*   SystemDictionary::_invoke_method_table = NULL;
 101 ProtectionDomainCacheTable*   SystemDictionary::_pd_cache_table = NULL;
 102 
 103 int         SystemDictionary::_number_of_modifications = 0;
 104 oop         SystemDictionary::_system_loader_lock_obj     =  NULL;
 105 
 106 InstanceKlass*      SystemDictionary::_well_known_klasses[SystemDictionary::WKID_LIMIT]
 107                                                           =  { NULL /*, NULL...*/ };
 108 
 109 InstanceKlass*      SystemDictionary::_box_klasses[T_VOID+1]      =  { NULL /*, NULL...*/ };
 110 
 111 oop         SystemDictionary::_java_system_loader         =  NULL;
 112 oop         SystemDictionary::_java_platform_loader       =  NULL;
 113 
 114 bool        SystemDictionary::_has_checkPackageAccess     =  false;
 115 
 116 // Default ProtectionDomainCacheSize value
 117 
 118 const int defaultProtectionDomainCacheSize = 1009;
 119 
 120 OopStorage* SystemDictionary::_vm_weak_oop_storage = NULL;
 121 
 122 
 123 // ----------------------------------------------------------------------------
 124 // Java-level SystemLoader and PlatformLoader
 125 
 126 oop SystemDictionary::java_system_loader() {
 127   return _java_system_loader;
 128 }
 129 
 130 oop SystemDictionary::java_platform_loader() {
 131   return _java_platform_loader;
 132 }
 133 
 134 void SystemDictionary::compute_java_loaders(TRAPS) {
 135   JavaValue result(T_OBJECT);
 136   InstanceKlass* class_loader_klass = SystemDictionary::ClassLoader_klass();
 137   JavaCalls::call_static(&result,
 138                          class_loader_klass,
 139                          vmSymbols::getSystemClassLoader_name(),
 140                          vmSymbols::void_classloader_signature(),
 141                          CHECK);
 142 
 143   _java_system_loader = (oop)result.get_jobject();
 144 
 145   JavaCalls::call_static(&result,
 146                          class_loader_klass,
 147                          vmSymbols::getPlatformClassLoader_name(),
 148                          vmSymbols::void_classloader_signature(),
 149                          CHECK);
 150 
 151   _java_platform_loader = (oop)result.get_jobject();
 152 }
 153 
 154 ClassLoaderData* SystemDictionary::register_loader(Handle class_loader) {
 155   if (class_loader() == NULL) return ClassLoaderData::the_null_class_loader_data();
 156   return ClassLoaderDataGraph::find_or_create(class_loader);
 157 }
 158 
 159 // ----------------------------------------------------------------------------
 160 // Parallel class loading check
 161 
 162 bool SystemDictionary::is_parallelCapable(Handle class_loader) {
 163   if (class_loader.is_null()) return true;
 164   if (AlwaysLockClassLoader) return false;
 165   return java_lang_ClassLoader::parallelCapable(class_loader());
 166 }
 167 // ----------------------------------------------------------------------------
 168 // ParallelDefineClass flag does not apply to bootclass loader
 169 bool SystemDictionary::is_parallelDefine(Handle class_loader) {
 170    if (class_loader.is_null()) return false;
 171    if (AllowParallelDefineClass && java_lang_ClassLoader::parallelCapable(class_loader())) {
 172      return true;
 173    }
 174    return false;
 175 }
 176 
 177 // Returns true if the passed class loader is the builtin application class loader
 178 // or a custom system class loader. A customer system class loader can be
 179 // specified via -Djava.system.class.loader.
 180 bool SystemDictionary::is_system_class_loader(oop class_loader) {
 181   if (class_loader == NULL) {
 182     return false;
 183   }
 184   return (class_loader->klass() == SystemDictionary::jdk_internal_loader_ClassLoaders_AppClassLoader_klass() ||
 185          oopDesc::equals(class_loader, _java_system_loader));
 186 }
 187 
 188 // Returns true if the passed class loader is the platform class loader.
 189 bool SystemDictionary::is_platform_class_loader(oop class_loader) {
 190   if (class_loader == NULL) {
 191     return false;
 192   }
 193   return (class_loader->klass() == SystemDictionary::jdk_internal_loader_ClassLoaders_PlatformClassLoader_klass());
 194 }
 195 
 196 // ----------------------------------------------------------------------------
 197 // Resolving of classes
 198 
 199 // Forwards to resolve_or_null
 200 
 201 Klass* SystemDictionary::resolve_or_fail(Symbol* class_name, Handle class_loader, Handle protection_domain, bool throw_error, TRAPS) {
 202   Klass* klass = resolve_or_null(class_name, class_loader, protection_domain, THREAD);
 203   if (HAS_PENDING_EXCEPTION || klass == NULL) {
 204     // can return a null klass
 205     klass = handle_resolution_exception(class_name, throw_error, klass, THREAD);
 206   }
 207   return klass;
 208 }
 209 
 210 Klass* SystemDictionary::handle_resolution_exception(Symbol* class_name,
 211                                                      bool throw_error,
 212                                                      Klass* klass, TRAPS) {
 213   if (HAS_PENDING_EXCEPTION) {
 214     // If we have a pending exception we forward it to the caller, unless throw_error is true,
 215     // in which case we have to check whether the pending exception is a ClassNotFoundException,
 216     // and if so convert it to a NoClassDefFoundError
 217     // And chain the original ClassNotFoundException
 218     if (throw_error && PENDING_EXCEPTION->is_a(SystemDictionary::ClassNotFoundException_klass())) {
 219       ResourceMark rm(THREAD);
 220       assert(klass == NULL, "Should not have result with exception pending");
 221       Handle e(THREAD, PENDING_EXCEPTION);
 222       CLEAR_PENDING_EXCEPTION;
 223       THROW_MSG_CAUSE_NULL(vmSymbols::java_lang_NoClassDefFoundError(), class_name->as_C_string(), e);
 224     } else {
 225       return NULL;
 226     }
 227   }
 228   // Class not found, throw appropriate error or exception depending on value of throw_error
 229   if (klass == NULL) {
 230     ResourceMark rm(THREAD);
 231     if (throw_error) {
 232       THROW_MSG_NULL(vmSymbols::java_lang_NoClassDefFoundError(), class_name->as_C_string());
 233     } else {
 234       THROW_MSG_NULL(vmSymbols::java_lang_ClassNotFoundException(), class_name->as_C_string());
 235     }
 236   }
 237   return klass;
 238 }
 239 
 240 
 241 Klass* SystemDictionary::resolve_or_fail(Symbol* class_name,
 242                                            bool throw_error, TRAPS)
 243 {
 244   return resolve_or_fail(class_name, Handle(), Handle(), throw_error, THREAD);
 245 }
 246 
 247 
 248 // Forwards to resolve_array_class_or_null or resolve_instance_class_or_null
 249 
 250 Klass* SystemDictionary::resolve_or_null(Symbol* class_name, Handle class_loader, Handle protection_domain, TRAPS) {
 251   if (FieldType::is_array(class_name)) {
 252     return resolve_array_class_or_null(class_name, class_loader, protection_domain, THREAD);
 253   } else {
 254     return resolve_instance_class_or_null_helper(class_name, class_loader, protection_domain, THREAD);
 255   }
 256 }
 257 
 258 // name may be in the form of "java/lang/Object" or "Ljava/lang/Object;"
 259 InstanceKlass* SystemDictionary::resolve_instance_class_or_null_helper(Symbol* class_name,
 260                                                                        Handle class_loader,
 261                                                                        Handle protection_domain,
 262                                                                        TRAPS) {
 263   assert(class_name != NULL && !FieldType::is_array(class_name), "must be");
 264   if (FieldType::is_obj(class_name)) {
 265     ResourceMark rm(THREAD);
 266     // Ignore wrapping L and ;.
 267     TempNewSymbol name = SymbolTable::new_symbol(class_name->as_C_string() + 1,
 268                                    class_name->utf8_length() - 2, CHECK_NULL);
 269     return resolve_instance_class_or_null(name, class_loader, protection_domain, THREAD);
 270   } else {
 271     return resolve_instance_class_or_null(class_name, class_loader, protection_domain, THREAD);
 272   }
 273 }
 274 
 275 Klass* SystemDictionary::resolve_or_null(Symbol* class_name, TRAPS) {
 276   return resolve_or_null(class_name, Handle(), Handle(), THREAD);
 277 }
 278 
 279 // Forwards to resolve_instance_class_or_null
 280 
 281 Klass* SystemDictionary::resolve_array_class_or_null(Symbol* class_name,
 282                                                      Handle class_loader,
 283                                                      Handle protection_domain,
 284                                                      TRAPS) {
 285   assert(FieldType::is_array(class_name), "must be array");
 286   Klass* k = NULL;
 287   FieldArrayInfo fd;
 288   // dimension and object_key in FieldArrayInfo are assigned as a side-effect
 289   // of this call
 290   BasicType t = FieldType::get_array_info(class_name, fd, CHECK_NULL);
 291   if (t == T_OBJECT) {
 292     // naked oop "k" is OK here -- we assign back into it
 293     k = SystemDictionary::resolve_instance_class_or_null(fd.object_key(),
 294                                                          class_loader,
 295                                                          protection_domain,
 296                                                          CHECK_NULL);
 297     if (k != NULL) {
 298       k = k->array_klass(fd.dimension(), CHECK_NULL);
 299     }
 300   } else {
 301     k = Universe::typeArrayKlassObj(t);
 302     k = TypeArrayKlass::cast(k)->array_klass(fd.dimension(), CHECK_NULL);
 303   }
 304   return k;
 305 }
 306 
 307 
 308 // Must be called for any super-class or super-interface resolution
 309 // during class definition to allow class circularity checking
 310 // super-interface callers:
 311 //    parse_interfaces - for defineClass & jvmtiRedefineClasses
 312 // super-class callers:
 313 //   ClassFileParser - for defineClass & jvmtiRedefineClasses
 314 //   load_shared_class - while loading a class from shared archive
 315 //   resolve_instance_class_or_null:
 316 //     via: handle_parallel_super_load
 317 //      when resolving a class that has an existing placeholder with
 318 //      a saved superclass [i.e. a defineClass is currently in progress]
 319 //      if another thread is trying to resolve the class, it must do
 320 //      super-class checks on its own thread to catch class circularity
 321 // This last call is critical in class circularity checking for cases
 322 // where classloading is delegated to different threads and the
 323 // classloader lock is released.
 324 // Take the case: Base->Super->Base
 325 //   1. If thread T1 tries to do a defineClass of class Base
 326 //    resolve_super_or_fail creates placeholder: T1, Base (super Super)
 327 //   2. resolve_instance_class_or_null does not find SD or placeholder for Super
 328 //    so it tries to load Super
 329 //   3. If we load the class internally, or user classloader uses same thread
 330 //      loadClassFromxxx or defineClass via parseClassFile Super ...
 331 //      3.1 resolve_super_or_fail creates placeholder: T1, Super (super Base)
 332 //      3.3 resolve_instance_class_or_null Base, finds placeholder for Base
 333 //      3.4 calls resolve_super_or_fail Base
 334 //      3.5 finds T1,Base -> throws class circularity
 335 //OR 4. If T2 tries to resolve Super via defineClass Super ...
 336 //      4.1 resolve_super_or_fail creates placeholder: T2, Super (super Base)
 337 //      4.2 resolve_instance_class_or_null Base, finds placeholder for Base (super Super)
 338 //      4.3 calls resolve_super_or_fail Super in parallel on own thread T2
 339 //      4.4 finds T2, Super -> throws class circularity
 340 // Must be called, even if superclass is null, since this is
 341 // where the placeholder entry is created which claims this
 342 // thread is loading this class/classloader.
 343 // Be careful when modifying this code: once you have run
 344 // placeholders()->find_and_add(PlaceholderTable::LOAD_SUPER),
 345 // you need to find_and_remove it before returning.
 346 // So be careful to not exit with a CHECK_ macro betweeen these calls.
 347 InstanceKlass* SystemDictionary::resolve_super_or_fail(Symbol* child_name,
 348                                                        Symbol* super_name,
 349                                                        Handle class_loader,
 350                                                        Handle protection_domain,
 351                                                        bool is_superclass,
 352                                                        TRAPS) {
 353   assert(!FieldType::is_array(super_name), "invalid super class name");
 354 #if INCLUDE_CDS
 355   if (DumpSharedSpaces) {
 356     // Special processing for handling UNREGISTERED shared classes.
 357     InstanceKlass* k = SystemDictionaryShared::dump_time_resolve_super_or_fail(child_name,
 358         super_name, class_loader, protection_domain, is_superclass, CHECK_NULL);
 359     if (k) {
 360       return k;
 361     }
 362   }
 363 #endif // INCLUDE_CDS
 364 
 365   // Double-check, if child class is already loaded, just return super-class,interface
 366   // Don't add a placedholder if already loaded, i.e. already in appropriate class loader
 367   // dictionary.
 368   // Make sure there's a placeholder for the *child* before resolving.
 369   // Used as a claim that this thread is currently loading superclass/classloader
 370   // Used here for ClassCircularity checks and also for heap verification
 371   // (every InstanceKlass needs to be in its class loader dictionary or have a placeholder).
 372   // Must check ClassCircularity before checking if super class is already loaded.
 373   //
 374   // We might not already have a placeholder if this child_name was
 375   // first seen via resolve_from_stream (jni_DefineClass or JVM_DefineClass);
 376   // the name of the class might not be known until the stream is actually
 377   // parsed.
 378   // Bugs 4643874, 4715493
 379 
 380   ClassLoaderData* loader_data = class_loader_data(class_loader);
 381   Dictionary* dictionary = loader_data->dictionary();
 382   unsigned int d_hash = dictionary->compute_hash(child_name);
 383   unsigned int p_hash = placeholders()->compute_hash(child_name);
 384   int p_index = placeholders()->hash_to_index(p_hash);
 385   // can't throw error holding a lock
 386   bool child_already_loaded = false;
 387   bool throw_circularity_error = false;
 388   {
 389     MutexLocker mu(SystemDictionary_lock, THREAD);
 390     InstanceKlass* childk = find_class(d_hash, child_name, dictionary);
 391     InstanceKlass* quicksuperk;
 392     // to support // loading: if child done loading, just return superclass
 393     // if super_name, & class_loader don't match:
 394     // if initial define, SD update will give LinkageError
 395     // if redefine: compare_class_versions will give HIERARCHY_CHANGED
 396     // so we don't throw an exception here.
 397     // see: nsk redefclass014 & java.lang.instrument Instrument032
 398     if ((childk != NULL ) && (is_superclass) &&
 399         ((quicksuperk = childk->java_super()) != NULL) &&
 400          ((quicksuperk->name() == super_name) &&
 401             (oopDesc::equals(quicksuperk->class_loader(), class_loader())))) {
 402            return quicksuperk;
 403     } else {
 404       PlaceholderEntry* probe = placeholders()->get_entry(p_index, p_hash, child_name, loader_data);
 405       if (probe && probe->check_seen_thread(THREAD, PlaceholderTable::LOAD_SUPER)) {
 406           throw_circularity_error = true;
 407       }
 408     }
 409     if (!throw_circularity_error) {
 410       // Be careful not to exit resolve_super
 411       PlaceholderEntry* newprobe = placeholders()->find_and_add(p_index, p_hash, child_name, loader_data, PlaceholderTable::LOAD_SUPER, super_name, THREAD);
 412     }
 413   }
 414   if (throw_circularity_error) {
 415       ResourceMark rm(THREAD);
 416       THROW_MSG_NULL(vmSymbols::java_lang_ClassCircularityError(), child_name->as_C_string());
 417   }
 418 
 419 // java.lang.Object should have been found above
 420   assert(super_name != NULL, "null super class for resolving");
 421   // Resolve the super class or interface, check results on return
 422   InstanceKlass* superk =
 423     SystemDictionary::resolve_instance_class_or_null_helper(super_name,
 424                                                             class_loader,
 425                                                             protection_domain,
 426                                                             THREAD);
 427 
 428   // Clean up of placeholders moved so that each classloadAction registrar self-cleans up
 429   // It is no longer necessary to keep the placeholder table alive until update_dictionary
 430   // or error. GC used to walk the placeholder table as strong roots.
 431   // The instanceKlass is kept alive because the class loader is on the stack,
 432   // which keeps the loader_data alive, as well as all instanceKlasses in
 433   // the loader_data. parseClassFile adds the instanceKlass to loader_data.
 434   {
 435     MutexLocker mu(SystemDictionary_lock, THREAD);
 436     placeholders()->find_and_remove(p_index, p_hash, child_name, loader_data, PlaceholderTable::LOAD_SUPER, THREAD);
 437     SystemDictionary_lock->notify_all();
 438   }
 439   if (HAS_PENDING_EXCEPTION || superk == NULL) {
 440     // can null superk
 441     Klass* k = handle_resolution_exception(super_name, true, superk, THREAD);
 442     assert(k == NULL || k == superk, "must be");
 443     if (k == NULL) {
 444       superk = NULL;
 445     }
 446   }
 447 
 448   return superk;
 449 }
 450 
 451 void SystemDictionary::validate_protection_domain(InstanceKlass* klass,
 452                                                   Handle class_loader,
 453                                                   Handle protection_domain,
 454                                                   TRAPS) {
 455   if(!has_checkPackageAccess()) return;
 456 
 457   // Now we have to call back to java to check if the initating class has access
 458   JavaValue result(T_VOID);
 459   LogTarget(Debug, protectiondomain) lt;
 460   if (lt.is_enabled()) {
 461     ResourceMark rm;
 462     // Print out trace information
 463     LogStream ls(lt);
 464     ls.print_cr("Checking package access");
 465     if (class_loader() != NULL) {
 466       ls.print("class loader: ");
 467       class_loader()->print_value_on(&ls);
 468     } else {
 469       ls.print_cr("class loader: NULL");
 470     }
 471     if (protection_domain() != NULL) {
 472       ls.print(" protection domain: ");
 473       protection_domain()->print_value_on(&ls);
 474     } else {
 475       ls.print_cr(" protection domain: NULL");
 476     }
 477     ls.print(" loading: "); klass->print_value_on(&ls);
 478     ls.cr();
 479   }
 480 
 481   // This handle and the class_loader handle passed in keeps this class from
 482   // being unloaded through several GC points.
 483   // The class_loader handle passed in is the initiating loader.
 484   Handle mirror(THREAD, klass->java_mirror());
 485 
 486   InstanceKlass* system_loader = SystemDictionary::ClassLoader_klass();
 487   JavaCalls::call_special(&result,
 488                          class_loader,
 489                          system_loader,
 490                          vmSymbols::checkPackageAccess_name(),
 491                          vmSymbols::class_protectiondomain_signature(),
 492                          mirror,
 493                          protection_domain,
 494                          THREAD);
 495 
 496   if (HAS_PENDING_EXCEPTION) {
 497     log_debug(protectiondomain)("DENIED !!!!!!!!!!!!!!!!!!!!!");
 498   } else {
 499    log_debug(protectiondomain)("granted");
 500   }
 501 
 502   if (HAS_PENDING_EXCEPTION) return;
 503 
 504   // If no exception has been thrown, we have validated the protection domain
 505   // Insert the protection domain of the initiating class into the set.
 506   {
 507     ClassLoaderData* loader_data = class_loader_data(class_loader);
 508     Dictionary* dictionary = loader_data->dictionary();
 509 
 510     Symbol*  kn = klass->name();
 511     unsigned int d_hash = dictionary->compute_hash(kn);
 512 
 513     MutexLocker mu(SystemDictionary_lock, THREAD);
 514     int d_index = dictionary->hash_to_index(d_hash);
 515     dictionary->add_protection_domain(d_index, d_hash, klass,
 516                                       protection_domain, THREAD);
 517   }
 518 }
 519 
 520 // We only get here if this thread finds that another thread
 521 // has already claimed the placeholder token for the current operation,
 522 // but that other thread either never owned or gave up the
 523 // object lock
 524 // Waits on SystemDictionary_lock to indicate placeholder table updated
 525 // On return, caller must recheck placeholder table state
 526 //
 527 // We only get here if
 528 //  1) custom classLoader, i.e. not bootstrap classloader
 529 //  2) custom classLoader has broken the class loader objectLock
 530 //     so another thread got here in parallel
 531 //
 532 // lockObject must be held.
 533 // Complicated dance due to lock ordering:
 534 // Must first release the classloader object lock to
 535 // allow initial definer to complete the class definition
 536 // and to avoid deadlock
 537 // Reclaim classloader lock object with same original recursion count
 538 // Must release SystemDictionary_lock after notify, since
 539 // class loader lock must be claimed before SystemDictionary_lock
 540 // to prevent deadlocks
 541 //
 542 // The notify allows applications that did an untimed wait() on
 543 // the classloader object lock to not hang.
 544 void SystemDictionary::double_lock_wait(Handle lockObject, TRAPS) {
 545   assert_lock_strong(SystemDictionary_lock);
 546 
 547   bool calledholdinglock
 548       = ObjectSynchronizer::current_thread_holds_lock((JavaThread*)THREAD, lockObject);
 549   assert(calledholdinglock,"must hold lock for notify");
 550   assert((!oopDesc::equals(lockObject(), _system_loader_lock_obj) && !is_parallelCapable(lockObject)), "unexpected double_lock_wait");
 551   ObjectSynchronizer::notifyall(lockObject, THREAD);
 552   intptr_t recursions =  ObjectSynchronizer::complete_exit(lockObject, THREAD);
 553   SystemDictionary_lock->wait();
 554   SystemDictionary_lock->unlock();
 555   ObjectSynchronizer::reenter(lockObject, recursions, THREAD);
 556   SystemDictionary_lock->lock();
 557 }
 558 
 559 // If the class in is in the placeholder table, class loading is in progress
 560 // For cases where the application changes threads to load classes, it
 561 // is critical to ClassCircularity detection that we try loading
 562 // the superclass on the same thread internally, so we do parallel
 563 // super class loading here.
 564 // This also is critical in cases where the original thread gets stalled
 565 // even in non-circularity situations.
 566 // Note: must call resolve_super_or_fail even if null super -
 567 // to force placeholder entry creation for this class for circularity detection
 568 // Caller must check for pending exception
 569 // Returns non-null Klass* if other thread has completed load
 570 // and we are done,
 571 // If return null Klass* and no pending exception, the caller must load the class
 572 InstanceKlass* SystemDictionary::handle_parallel_super_load(
 573     Symbol* name, Symbol* superclassname, Handle class_loader,
 574     Handle protection_domain, Handle lockObject, TRAPS) {
 575 
 576   ClassLoaderData* loader_data = class_loader_data(class_loader);
 577   Dictionary* dictionary = loader_data->dictionary();
 578   unsigned int d_hash = dictionary->compute_hash(name);
 579   unsigned int p_hash = placeholders()->compute_hash(name);
 580   int p_index = placeholders()->hash_to_index(p_hash);
 581 
 582   // superk is not used, resolve_super called for circularity check only
 583   // This code is reached in two situations. One if this thread
 584   // is loading the same class twice (e.g. ClassCircularity, or
 585   // java.lang.instrument).
 586   // The second is if another thread started the resolve_super first
 587   // and has not yet finished.
 588   // In both cases the original caller will clean up the placeholder
 589   // entry on error.
 590   Klass* superk = SystemDictionary::resolve_super_or_fail(name,
 591                                                           superclassname,
 592                                                           class_loader,
 593                                                           protection_domain,
 594                                                           true,
 595                                                           CHECK_NULL);
 596 
 597   // parallelCapable class loaders do NOT wait for parallel superclass loads to complete
 598   // Serial class loaders and bootstrap classloader do wait for superclass loads
 599  if (!class_loader.is_null() && is_parallelCapable(class_loader)) {
 600     MutexLocker mu(SystemDictionary_lock, THREAD);
 601     // Check if classloading completed while we were loading superclass or waiting
 602     return find_class(d_hash, name, dictionary);
 603   }
 604 
 605   // must loop to both handle other placeholder updates
 606   // and spurious notifications
 607   bool super_load_in_progress = true;
 608   PlaceholderEntry* placeholder;
 609   while (super_load_in_progress) {
 610     MutexLocker mu(SystemDictionary_lock, THREAD);
 611     // Check if classloading completed while we were loading superclass or waiting
 612     InstanceKlass* check = find_class(d_hash, name, dictionary);
 613     if (check != NULL) {
 614       // Klass is already loaded, so just return it
 615       return check;
 616     } else {
 617       placeholder = placeholders()->get_entry(p_index, p_hash, name, loader_data);
 618       if (placeholder && placeholder->super_load_in_progress() ){
 619         // We only get here if the application has released the
 620         // classloader lock when another thread was in the middle of loading a
 621         // superclass/superinterface for this class, and now
 622         // this thread is also trying to load this class.
 623         // To minimize surprises, the first thread that started to
 624         // load a class should be the one to complete the loading
 625         // with the classfile it initially expected.
 626         // This logic has the current thread wait once it has done
 627         // all the superclass/superinterface loading it can, until
 628         // the original thread completes the class loading or fails
 629         // If it completes we will use the resulting InstanceKlass
 630         // which we will find below in the systemDictionary.
 631         // We also get here for parallel bootstrap classloader
 632         if (class_loader.is_null()) {
 633           SystemDictionary_lock->wait();
 634         } else {
 635           double_lock_wait(lockObject, THREAD);
 636         }
 637       } else {
 638         // If not in SD and not in PH, other thread's load must have failed
 639         super_load_in_progress = false;
 640       }
 641     }
 642   }
 643   return NULL;
 644 }
 645 
 646 static void post_class_load_event(EventClassLoad* event, const InstanceKlass* k, const ClassLoaderData* init_cld) {
 647   assert(event != NULL, "invariant");
 648   assert(k != NULL, "invariant");
 649   assert(event->should_commit(), "invariant");
 650   event->set_loadedClass(k);
 651   event->set_definingClassLoader(k->class_loader_data());
 652   event->set_initiatingClassLoader(init_cld);
 653   event->commit();
 654 }
 655 
 656 
 657 // Be careful when modifying this code: once you have run
 658 // placeholders()->find_and_add(PlaceholderTable::LOAD_INSTANCE),
 659 // you need to find_and_remove it before returning.
 660 // So be careful to not exit with a CHECK_ macro betweeen these calls.
 661 //
 662 // name must be in the form of "java/lang/Object" -- cannot be "Ljava/lang/Object;"
 663 InstanceKlass* SystemDictionary::resolve_instance_class_or_null(Symbol* name,
 664                                                                 Handle class_loader,
 665                                                                 Handle protection_domain,
 666                                                                 TRAPS) {
 667   assert(name != NULL && !FieldType::is_array(name) &&
 668          !FieldType::is_obj(name), "invalid class name");
 669 
 670   EventClassLoad class_load_start_event;
 671 
 672   HandleMark hm(THREAD);
 673 
 674   // Fix for 4474172; see evaluation for more details
 675   class_loader = Handle(THREAD, java_lang_ClassLoader::non_reflection_class_loader(class_loader()));
 676   ClassLoaderData* loader_data = register_loader(class_loader);
 677   Dictionary* dictionary = loader_data->dictionary();
 678   unsigned int d_hash = dictionary->compute_hash(name);
 679 
 680   // Do lookup to see if class already exist and the protection domain
 681   // has the right access
 682   // This call uses find which checks protection domain already matches
 683   // All subsequent calls use find_class, and set has_loaded_class so that
 684   // before we return a result we call out to java to check for valid protection domain
 685   // to allow returning the Klass* and add it to the pd_set if it is valid
 686   {
 687     InstanceKlass* probe = dictionary->find(d_hash, name, protection_domain);
 688     if (probe != NULL) return probe;
 689   }
 690 
 691   // Non-bootstrap class loaders will call out to class loader and
 692   // define via jvm/jni_DefineClass which will acquire the
 693   // class loader object lock to protect against multiple threads
 694   // defining the class in parallel by accident.
 695   // This lock must be acquired here so the waiter will find
 696   // any successful result in the SystemDictionary and not attempt
 697   // the define.
 698   // ParallelCapable Classloaders and the bootstrap classloader
 699   // do not acquire lock here.
 700   bool DoObjectLock = true;
 701   if (is_parallelCapable(class_loader)) {
 702     DoObjectLock = false;
 703   }
 704 
 705   unsigned int p_hash = placeholders()->compute_hash(name);
 706   int p_index = placeholders()->hash_to_index(p_hash);
 707 
 708   // Class is not in SystemDictionary so we have to do loading.
 709   // Make sure we are synchronized on the class loader before we proceed
 710   Handle lockObject = compute_loader_lock_object(class_loader, THREAD);
 711   check_loader_lock_contention(lockObject, THREAD);
 712   ObjectLocker ol(lockObject, THREAD, DoObjectLock);
 713 
 714   // Check again (after locking) if class already exist in SystemDictionary
 715   bool class_has_been_loaded   = false;
 716   bool super_load_in_progress  = false;
 717   bool havesupername = false;
 718   InstanceKlass* k = NULL;
 719   PlaceholderEntry* placeholder;
 720   Symbol* superclassname = NULL;
 721 
 722   assert(THREAD->can_call_java(),
 723          "can not load classes with compiler thread: class=%s, classloader=%s",
 724          name->as_C_string(),
 725          class_loader.is_null() ? "null" : class_loader->klass()->name()->as_C_string());
 726   {
 727     MutexLocker mu(SystemDictionary_lock, THREAD);
 728     InstanceKlass* check = find_class(d_hash, name, dictionary);
 729     if (check != NULL) {
 730       // InstanceKlass is already loaded, so just return it
 731       class_has_been_loaded = true;
 732       k = check;
 733     } else {
 734       placeholder = placeholders()->get_entry(p_index, p_hash, name, loader_data);
 735       if (placeholder && placeholder->super_load_in_progress()) {
 736          super_load_in_progress = true;
 737          if (placeholder->havesupername() == true) {
 738            superclassname = placeholder->supername();
 739            havesupername = true;
 740          }
 741       }
 742     }
 743   }
 744 
 745   // If the class is in the placeholder table, class loading is in progress
 746   if (super_load_in_progress && havesupername==true) {
 747     k = handle_parallel_super_load(name,
 748                                    superclassname,
 749                                    class_loader,
 750                                    protection_domain,
 751                                    lockObject, THREAD);
 752     if (HAS_PENDING_EXCEPTION) {
 753       return NULL;
 754     }
 755     if (k != NULL) {
 756       class_has_been_loaded = true;
 757     }
 758   }
 759 
 760   bool throw_circularity_error = false;
 761   if (!class_has_been_loaded) {
 762     bool load_instance_added = false;
 763 
 764     // add placeholder entry to record loading instance class
 765     // Five cases:
 766     // All cases need to prevent modifying bootclasssearchpath
 767     // in parallel with a classload of same classname
 768     // Redefineclasses uses existence of the placeholder for the duration
 769     // of the class load to prevent concurrent redefinition of not completely
 770     // defined classes.
 771     // case 1. traditional classloaders that rely on the classloader object lock
 772     //   - no other need for LOAD_INSTANCE
 773     // case 2. traditional classloaders that break the classloader object lock
 774     //    as a deadlock workaround. Detection of this case requires that
 775     //    this check is done while holding the classloader object lock,
 776     //    and that lock is still held when calling classloader's loadClass.
 777     //    For these classloaders, we ensure that the first requestor
 778     //    completes the load and other requestors wait for completion.
 779     // case 3. Bootstrap classloader - don't own objectLocker
 780     //    This classloader supports parallelism at the classloader level,
 781     //    but only allows a single load of a class/classloader pair.
 782     //    No performance benefit and no deadlock issues.
 783     // case 4. parallelCapable user level classloaders - without objectLocker
 784     //    Allow parallel classloading of a class/classloader pair
 785 
 786     {
 787       MutexLocker mu(SystemDictionary_lock, THREAD);
 788       if (class_loader.is_null() || !is_parallelCapable(class_loader)) {
 789         PlaceholderEntry* oldprobe = placeholders()->get_entry(p_index, p_hash, name, loader_data);
 790         if (oldprobe) {
 791           // only need check_seen_thread once, not on each loop
 792           // 6341374 java/lang/Instrument with -Xcomp
 793           if (oldprobe->check_seen_thread(THREAD, PlaceholderTable::LOAD_INSTANCE)) {
 794             throw_circularity_error = true;
 795           } else {
 796             // case 1: traditional: should never see load_in_progress.
 797             while (!class_has_been_loaded && oldprobe && oldprobe->instance_load_in_progress()) {
 798 
 799               // case 3: bootstrap classloader: prevent futile classloading,
 800               // wait on first requestor
 801               if (class_loader.is_null()) {
 802                 SystemDictionary_lock->wait();
 803               } else {
 804               // case 2: traditional with broken classloader lock. wait on first
 805               // requestor.
 806                 double_lock_wait(lockObject, THREAD);
 807               }
 808               // Check if classloading completed while we were waiting
 809               InstanceKlass* check = find_class(d_hash, name, dictionary);
 810               if (check != NULL) {
 811                 // Klass is already loaded, so just return it
 812                 k = check;
 813                 class_has_been_loaded = true;
 814               }
 815               // check if other thread failed to load and cleaned up
 816               oldprobe = placeholders()->get_entry(p_index, p_hash, name, loader_data);
 817             }
 818           }
 819         }
 820       }
 821       // All cases: add LOAD_INSTANCE holding SystemDictionary_lock
 822       // case 4: parallelCapable: allow competing threads to try
 823       // LOAD_INSTANCE in parallel
 824 
 825       if (!throw_circularity_error && !class_has_been_loaded) {
 826         PlaceholderEntry* newprobe = placeholders()->find_and_add(p_index, p_hash, name, loader_data, PlaceholderTable::LOAD_INSTANCE, NULL, THREAD);
 827         load_instance_added = true;
 828         // For class loaders that do not acquire the classloader object lock,
 829         // if they did not catch another thread holding LOAD_INSTANCE,
 830         // need a check analogous to the acquire ObjectLocker/find_class
 831         // i.e. now that we hold the LOAD_INSTANCE token on loading this class/CL
 832         // one final check if the load has already completed
 833         // class loaders holding the ObjectLock shouldn't find the class here
 834         InstanceKlass* check = find_class(d_hash, name, dictionary);
 835         if (check != NULL) {
 836         // Klass is already loaded, so return it after checking/adding protection domain
 837           k = check;
 838           class_has_been_loaded = true;
 839         }
 840       }
 841     }
 842 
 843     // must throw error outside of owning lock
 844     if (throw_circularity_error) {
 845       assert(!HAS_PENDING_EXCEPTION && load_instance_added == false,"circularity error cleanup");
 846       ResourceMark rm(THREAD);
 847       THROW_MSG_NULL(vmSymbols::java_lang_ClassCircularityError(), name->as_C_string());
 848     }
 849 
 850     if (!class_has_been_loaded) {
 851 
 852       // Do actual loading
 853       k = load_instance_class(name, class_loader, THREAD);
 854 
 855       // If everything was OK (no exceptions, no null return value), and
 856       // class_loader is NOT the defining loader, do a little more bookkeeping.
 857       if (!HAS_PENDING_EXCEPTION && k != NULL &&
 858         !oopDesc::equals(k->class_loader(), class_loader())) {
 859 
 860         check_constraints(d_hash, k, class_loader, false, THREAD);
 861 
 862         // Need to check for a PENDING_EXCEPTION again; check_constraints
 863         // can throw but we may have to remove entry from the placeholder table below.
 864         if (!HAS_PENDING_EXCEPTION) {
 865           // Record dependency for non-parent delegation.
 866           // This recording keeps the defining class loader of the klass (k) found
 867           // from being unloaded while the initiating class loader is loaded
 868           // even if the reference to the defining class loader is dropped
 869           // before references to the initiating class loader.
 870           loader_data->record_dependency(k);
 871 
 872           { // Grabbing the Compile_lock prevents systemDictionary updates
 873             // during compilations.
 874             MutexLocker mu(Compile_lock, THREAD);
 875             update_dictionary(d_hash, p_index, p_hash,
 876               k, class_loader, THREAD);
 877           }
 878 
 879           if (JvmtiExport::should_post_class_load()) {
 880             Thread *thread = THREAD;
 881             assert(thread->is_Java_thread(), "thread->is_Java_thread()");
 882             JvmtiExport::post_class_load((JavaThread *) thread, k);
 883           }
 884         }
 885       }
 886     } // load_instance_class
 887 
 888     if (load_instance_added == true) {
 889       // clean up placeholder entries for LOAD_INSTANCE success or error
 890       // This brackets the SystemDictionary updates for both defining
 891       // and initiating loaders
 892       MutexLocker mu(SystemDictionary_lock, THREAD);
 893       placeholders()->find_and_remove(p_index, p_hash, name, loader_data, PlaceholderTable::LOAD_INSTANCE, THREAD);
 894       SystemDictionary_lock->notify_all();
 895     }
 896   }
 897 
 898   if (HAS_PENDING_EXCEPTION || k == NULL) {
 899     return NULL;
 900   }
 901   if (class_load_start_event.should_commit()) {
 902     post_class_load_event(&class_load_start_event, k, loader_data);
 903   }
 904 #ifdef ASSERT
 905   {
 906     ClassLoaderData* loader_data = k->class_loader_data();
 907     MutexLocker mu(SystemDictionary_lock, THREAD);
 908     InstanceKlass* kk = find_class(name, loader_data);
 909     assert(kk == k, "should be present in dictionary");
 910   }
 911 #endif
 912 
 913   // return if the protection domain in NULL
 914   if (protection_domain() == NULL) return k;
 915 
 916   // Check the protection domain has the right access
 917   if (dictionary->is_valid_protection_domain(d_hash, name,
 918                                              protection_domain)) {
 919     return k;
 920   }
 921 
 922   // Verify protection domain. If it fails an exception is thrown
 923   validate_protection_domain(k, class_loader, protection_domain, CHECK_NULL);
 924 
 925   return k;
 926 }
 927 
 928 
 929 // This routine does not lock the system dictionary.
 930 //
 931 // Since readers don't hold a lock, we must make sure that system
 932 // dictionary entries are only removed at a safepoint (when only one
 933 // thread is running), and are added to in a safe way (all links must
 934 // be updated in an MT-safe manner).
 935 //
 936 // Callers should be aware that an entry could be added just after
 937 // _dictionary->bucket(index) is read here, so the caller will not see
 938 // the new entry.
 939 
 940 Klass* SystemDictionary::find(Symbol* class_name,
 941                               Handle class_loader,
 942                               Handle protection_domain,
 943                               TRAPS) {
 944 
 945   // The result of this call should be consistent with the result
 946   // of the call to resolve_instance_class_or_null().
 947   // See evaluation 6790209 and 4474172 for more details.
 948   class_loader = Handle(THREAD, java_lang_ClassLoader::non_reflection_class_loader(class_loader()));
 949   ClassLoaderData* loader_data = ClassLoaderData::class_loader_data_or_null(class_loader());
 950 
 951   if (loader_data == NULL) {
 952     // If the ClassLoaderData has not been setup,
 953     // then the class loader has no entries in the dictionary.
 954     return NULL;
 955   }
 956 
 957   Dictionary* dictionary = loader_data->dictionary();
 958   unsigned int d_hash = dictionary->compute_hash(class_name);
 959   return dictionary->find(d_hash, class_name,
 960                           protection_domain);
 961 }
 962 
 963 
 964 // Look for a loaded instance or array klass by name.  Do not do any loading.
 965 // return NULL in case of error.
 966 Klass* SystemDictionary::find_instance_or_array_klass(Symbol* class_name,
 967                                                       Handle class_loader,
 968                                                       Handle protection_domain,
 969                                                       TRAPS) {
 970   Klass* k = NULL;
 971   assert(class_name != NULL, "class name must be non NULL");
 972 
 973   if (FieldType::is_array(class_name)) {
 974     // The name refers to an array.  Parse the name.
 975     // dimension and object_key in FieldArrayInfo are assigned as a
 976     // side-effect of this call
 977     FieldArrayInfo fd;
 978     BasicType t = FieldType::get_array_info(class_name, fd, CHECK_(NULL));
 979     if (t != T_OBJECT) {
 980       k = Universe::typeArrayKlassObj(t);
 981     } else {
 982       k = SystemDictionary::find(fd.object_key(), class_loader, protection_domain, THREAD);
 983     }
 984     if (k != NULL) {
 985       k = k->array_klass_or_null(fd.dimension());
 986     }
 987   } else {
 988     k = find(class_name, class_loader, protection_domain, THREAD);
 989   }
 990   return k;
 991 }
 992 
 993 // Note: this method is much like resolve_from_stream, but
 994 // does not publish the classes via the SystemDictionary.
 995 // Handles Lookup.defineClass nonfindable, unsafe_DefineAnonymousClass
 996 // and redefineclasses. RedefinedClasses do not add to the class hierarchy.
 997 InstanceKlass* SystemDictionary::parse_stream(Symbol* class_name,
 998                                               Handle class_loader,
 999                                               Handle protection_domain,
1000                                               ClassFileStream* st,
1001                                               const InstanceKlass* unsafe_anonymous_host,
1002                                               GrowableArray<Handle>* cp_patches,
1003                                               const bool is_nonfindable,
1004                                               const bool is_weaknonfindable,
1005                                               const bool can_access_vm_annotations,
1006                                               InstanceKlass* dynamic_nest_host,
1007                                               Handle classData,
1008                                               TRAPS) {
1009 
1010   EventClassLoad class_load_start_event;
1011 
1012   ClassLoaderData* loader_data;
1013 
1014   if (unsafe_anonymous_host != NULL) {
1015     // - for unsafe anonymous class: create a new short-lived CLD that uses the same
1016     //                               class loader as the unsafe_anonymous_host.
1017     guarantee(oopDesc::equals(unsafe_anonymous_host->class_loader(), class_loader()), "should be the same");
1018     loader_data = ClassLoaderData::shortlived_class_loader_data(class_loader);
1019   } else if (is_nonfindable) {
1020     // - for weak nonfindable class: create a new short-lived CLD whose loader is
1021     //                               the Lookup class' loader.
1022     // - for nonfindable class: add the class to the Lookup class' loader's CLD.
1023     if (is_weaknonfindable) {
1024       loader_data = ClassLoaderData::shortlived_class_loader_data(class_loader);
1025     } else {
1026       // This nonfindable class goes into the regular CLD pool for this loader.
1027       loader_data = register_loader(class_loader);
1028     }
1029   } else {
1030     loader_data = ClassLoaderData::class_loader_data(class_loader());
1031   }
1032 
1033   assert(st != NULL, "invariant");
1034   assert(st->need_verify(), "invariant");
1035 
1036   // Parse stream and create a klass.
1037   // Note that we do this even though this klass might
1038   // already be present in the SystemDictionary, otherwise we would not
1039   // throw potential ClassFormatErrors.
1040 
1041   InstanceKlass* k = KlassFactory::create_from_stream(st,
1042                                                       class_name,
1043                                                       loader_data,
1044                                                       protection_domain,
1045                                                       unsafe_anonymous_host,
1046                                                       cp_patches,
1047                                                       is_nonfindable,
1048                                                       can_access_vm_annotations,
1049                                                       dynamic_nest_host,
1050                                                       classData,
1051                                                       CHECK_NULL);
1052 
1053   if ((is_nonfindable || (unsafe_anonymous_host != NULL)) && k != NULL) {
1054     // Weak nonfindable and unsafe anonymous classes must update ClassLoaderData holder
1055     // so that they can be unloaded when the mirror is no longer referenced.
1056     if (is_weaknonfindable || (unsafe_anonymous_host != NULL)) {
1057       k->class_loader_data()->initialize_holder(Handle(THREAD, k->java_mirror()));
1058     }
1059 
1060     {
1061       MutexLocker mu_r(Compile_lock, THREAD);
1062 
1063       // Add to class hierarchy, initialize vtables, and do possible
1064       // deoptimizations.
1065       add_to_hierarchy(k, CHECK_NULL); // No exception, but can block
1066 
1067       // But, do not add to dictionary.
1068 
1069       // compiled code dependencies need to be validated anyway
1070       notice_modification();
1071     }
1072 
1073     // Rewrite and patch constant pool here.
1074     k->link_class(CHECK_NULL);
1075     if (cp_patches != NULL) {
1076       k->constants()->patch_resolved_references(cp_patches);
1077     }
1078 
1079     // Initialize it now, since nobody else will.
1080     // FIXME: why must we eager initialize? It should be initialized upon use.
1081     k->eager_initialize(CHECK_NULL);
1082 
1083     // notify jvmti
1084     if (JvmtiExport::should_post_class_load()) {
1085         assert(THREAD->is_Java_thread(), "thread->is_Java_thread()");
1086         JvmtiExport::post_class_load((JavaThread *) THREAD, k);
1087     }
1088     if (class_load_start_event.should_commit()) {
1089       post_class_load_event(&class_load_start_event, k, loader_data);
1090     }
1091   }
1092   assert(unsafe_anonymous_host != NULL || NULL == cp_patches,
1093          "cp_patches only found with unsafe_anonymous_host");
1094 
1095   return k;
1096 }
1097 
1098 // Add a klass to the system from a stream (called by jni_DefineClass and
1099 // JVM_DefineClass).
1100 // Note: class_name can be NULL. In that case we do not know the name of
1101 // the class until we have parsed the stream.
1102 
1103 InstanceKlass* SystemDictionary::resolve_from_stream(Symbol* class_name,
1104                                                      Handle class_loader,
1105                                                      Handle protection_domain,
1106                                                      ClassFileStream* st,
1107                                                      InstanceKlass* dynamic_nest_host,
1108                                                      TRAPS) {
1109 
1110   HandleMark hm(THREAD);
1111 
1112   // Classloaders that support parallelism, e.g. bootstrap classloader,
1113   // do not acquire lock here
1114   bool DoObjectLock = true;
1115   if (is_parallelCapable(class_loader)) {
1116     DoObjectLock = false;
1117   }
1118 
1119   ClassLoaderData* loader_data = register_loader(class_loader);
1120 
1121   // Make sure we are synchronized on the class loader before we proceed
1122   Handle lockObject = compute_loader_lock_object(class_loader, THREAD);
1123   check_loader_lock_contention(lockObject, THREAD);
1124   ObjectLocker ol(lockObject, THREAD, DoObjectLock);
1125 
1126   assert(st != NULL, "invariant");
1127 
1128   // Parse the stream and create a klass.
1129   // Note that we do this even though this klass might
1130   // already be present in the SystemDictionary, otherwise we would not
1131   // throw potential ClassFormatErrors.
1132  InstanceKlass* k = NULL;
1133 
1134 #if INCLUDE_CDS
1135   if (!DumpSharedSpaces) {
1136     k = SystemDictionaryShared::lookup_from_stream(class_name,
1137                                                    class_loader,
1138                                                    protection_domain,
1139                                                    st,
1140                                                    CHECK_NULL);
1141   }
1142 #endif
1143 
1144   if (k == NULL) {
1145     if (st->buffer() == NULL) {
1146       return NULL;
1147     }
1148     k = KlassFactory::create_from_stream(st,
1149                                          class_name,
1150                                          loader_data,
1151                                          protection_domain,
1152                                          NULL,  // unsafe_anonymous_host
1153                                          NULL,  // cp_patches
1154                                          false, // is_nonfindable
1155                                          false, // can_access_vm_annotations
1156                                          dynamic_nest_host,
1157                                          Handle(), // classData
1158                                          CHECK_NULL);
1159   }
1160 
1161   assert(k != NULL, "no klass created");
1162   Symbol* h_name = k->name();
1163   assert(class_name == NULL || class_name == h_name, "name mismatch");
1164 
1165   // Add class just loaded
1166   // If a class loader supports parallel classloading handle parallel define requests
1167   // find_or_define_instance_class may return a different InstanceKlass
1168   if (is_parallelCapable(class_loader)) {
1169     InstanceKlass* defined_k = find_or_define_instance_class(h_name, class_loader, k, THREAD);
1170     if (!HAS_PENDING_EXCEPTION && defined_k != k) {
1171       // If a parallel capable class loader already defined this class, register 'k' for cleanup.
1172       assert(defined_k != NULL, "Should have a klass if there's no exception");
1173       loader_data->add_to_deallocate_list(k);
1174       k = defined_k;
1175     }
1176   } else {
1177     define_instance_class(k, THREAD);
1178   }
1179 
1180   // If defining the class throws an exception register 'k' for cleanup.
1181   if (HAS_PENDING_EXCEPTION) {
1182     assert(k != NULL, "Must have an instance klass here!");
1183     loader_data->add_to_deallocate_list(k);
1184     return NULL;
1185   }
1186 
1187   // Make sure we have an entry in the SystemDictionary on success
1188   debug_only( {
1189     MutexLocker mu(SystemDictionary_lock, THREAD);
1190 
1191     Klass* check = find_class(h_name, k->class_loader_data());
1192     assert(check == k, "should be present in the dictionary");
1193   } );
1194 
1195   return k;
1196 }
1197 
1198 #if INCLUDE_CDS
1199 // Load a class for boot loader from the shared spaces. This also
1200 // forces the super class and all interfaces to be loaded.
1201 InstanceKlass* SystemDictionary::load_shared_boot_class(Symbol* class_name,
1202                                                         TRAPS) {
1203   InstanceKlass* ik = SystemDictionaryShared::find_builtin_class(class_name);
1204   if (ik != NULL && ik->is_shared_boot_class()) {
1205     return load_shared_class(ik, Handle(), Handle(), NULL, THREAD);
1206   }
1207   return NULL;
1208 }
1209 
1210 // Check if a shared class can be loaded by the specific classloader:
1211 //
1212 // NULL classloader:
1213 //   - Module class from "modules" jimage. ModuleEntry must be defined in the classloader.
1214 //   - Class from -Xbootclasspath/a. The class has no defined PackageEntry, or must
1215 //     be defined in an unnamed module.
1216 bool SystemDictionary::is_shared_class_visible(Symbol* class_name,
1217                                                InstanceKlass* ik,
1218                                                Handle class_loader, TRAPS) {
1219   assert(!ModuleEntryTable::javabase_moduleEntry()->is_patched(),
1220          "Cannot use sharing if java.base is patched");
1221   ResourceMark rm;
1222   int path_index = ik->shared_classpath_index();
1223   ClassLoaderData* loader_data = class_loader_data(class_loader);
1224   if (path_index < 0) {
1225     // path_index < 0 indicates that the class is intended for a custom loader
1226     // and should not be loaded by boot/platform/app loaders
1227     if (loader_data->is_builtin_class_loader_data()) {
1228       return false;
1229     } else {
1230       return true;
1231     }
1232   }
1233   SharedClassPathEntry* ent =
1234             (SharedClassPathEntry*)FileMapInfo::shared_path(path_index);
1235   if (!Universe::is_module_initialized()) {
1236     assert(ent != NULL && ent->is_modules_image(),
1237            "Loading non-bootstrap classes before the module system is initialized");
1238     assert(class_loader.is_null(), "sanity");
1239     return true;
1240   }
1241   // Get the pkg_entry from the classloader
1242   TempNewSymbol pkg_name = NULL;
1243   PackageEntry* pkg_entry = NULL;
1244   ModuleEntry* mod_entry = NULL;
1245   const char* pkg_string = NULL;
1246   pkg_name = InstanceKlass::package_from_name(class_name, CHECK_false);
1247   if (pkg_name != NULL) {
1248     pkg_string = pkg_name->as_C_string();
1249     if (loader_data != NULL) {
1250       pkg_entry = loader_data->packages()->lookup_only(pkg_name);
1251     }
1252     if (pkg_entry != NULL) {
1253       mod_entry = pkg_entry->module();
1254     }
1255   }
1256 
1257   // If the archived class is from a module that has been patched at runtime,
1258   // the class cannot be loaded from the archive.
1259   if (mod_entry != NULL && mod_entry->is_patched()) {
1260     return false;
1261   }
1262 
1263   if (class_loader.is_null()) {
1264     assert(ent != NULL, "Shared class for NULL classloader must have valid SharedClassPathEntry");
1265     // The NULL classloader can load archived class originated from the
1266     // "modules" jimage and the -Xbootclasspath/a. For class from the
1267     // "modules" jimage, the PackageEntry/ModuleEntry must be defined
1268     // by the NULL classloader.
1269     if (mod_entry != NULL) {
1270       // PackageEntry/ModuleEntry is found in the classloader. Check if the
1271       // ModuleEntry's location agrees with the archived class' origination.
1272       if (ent->is_modules_image() && mod_entry->location()->starts_with("jrt:")) {
1273         return true; // Module class from the "module" jimage
1274       }
1275     }
1276 
1277     // If the archived class is not from the "module" jimage, the class can be
1278     // loaded by the NULL classloader if
1279     //
1280     // 1. the class is from the unamed package
1281     // 2. or, the class is not from a module defined in the NULL classloader
1282     // 3. or, the class is from an unamed module
1283     if (!ent->is_modules_image() && ik->is_shared_boot_class()) {
1284       // the class is from the -Xbootclasspath/a
1285       if (pkg_string == NULL ||
1286           pkg_entry == NULL ||
1287           pkg_entry->in_unnamed_module()) {
1288         assert(mod_entry == NULL ||
1289                mod_entry == loader_data->unnamed_module(),
1290                "the unnamed module is not defined in the classloader");
1291         return true;
1292       }
1293     }
1294     return false;
1295   } else {
1296     bool res = SystemDictionaryShared::is_shared_class_visible_for_classloader(
1297               ik, class_loader, pkg_string, pkg_name,
1298               pkg_entry, mod_entry, CHECK_(false));
1299     return res;
1300   }
1301 }
1302 
1303 InstanceKlass* SystemDictionary::load_shared_class(InstanceKlass* ik,
1304                                                    Handle class_loader,
1305                                                    Handle protection_domain,
1306                                                    const ClassFileStream *cfs,
1307                                                    TRAPS) {
1308 
1309   if (ik != NULL) {
1310     Symbol* class_name = ik->name();
1311 
1312     bool visible = is_shared_class_visible(
1313                             class_name, ik, class_loader, CHECK_NULL);
1314     if (!visible) {
1315       return NULL;
1316     }
1317 
1318     // Resolve the superclass and interfaces. They must be the same
1319     // as in dump time, because the layout of <ik> depends on
1320     // the specific layout of ik->super() and ik->local_interfaces().
1321     //
1322     // If unexpected superclass or interfaces are found, we cannot
1323     // load <ik> from the shared archive.
1324 
1325     if (ik->super() != NULL) {
1326       Symbol*  cn = ik->super()->name();
1327       Klass *s = resolve_super_or_fail(class_name, cn,
1328                                        class_loader, protection_domain, true, CHECK_NULL);
1329       if (s != ik->super()) {
1330         // The dynamically resolved super class is not the same as the one we used during dump time,
1331         // so we cannot use ik.
1332         return NULL;
1333       } else {
1334         assert(s->is_shared(), "must be");
1335       }
1336     }
1337 
1338     Array<InstanceKlass*>* interfaces = ik->local_interfaces();
1339     int num_interfaces = interfaces->length();
1340     for (int index = 0; index < num_interfaces; index++) {
1341       InstanceKlass* k = interfaces->at(index);
1342       Symbol* name  = k->name();
1343       Klass* i = resolve_super_or_fail(class_name, name, class_loader, protection_domain, false, CHECK_NULL);
1344       if (k != i) {
1345         // The dynamically resolved interface class is not the same as the one we used during dump time,
1346         // so we cannot use ik.
1347         return NULL;
1348       } else {
1349         assert(i->is_shared(), "must be");
1350       }
1351     }
1352 
1353     InstanceKlass* new_ik = KlassFactory::check_shared_class_file_load_hook(
1354         ik, class_name, class_loader, protection_domain, cfs, CHECK_NULL);
1355     if (new_ik != NULL) {
1356       // The class is changed by CFLH. Return the new class. The shared class is
1357       // not used.
1358       return new_ik;
1359     }
1360 
1361     // Adjust methods to recover missing data.  They need addresses for
1362     // interpreter entry points and their default native method address
1363     // must be reset.
1364 
1365     // Updating methods must be done under a lock so multiple
1366     // threads don't update these in parallel
1367     //
1368     // Shared classes are all currently loaded by either the bootstrap or
1369     // internal parallel class loaders, so this will never cause a deadlock
1370     // on a custom class loader lock.
1371 
1372     ClassLoaderData* loader_data = ClassLoaderData::class_loader_data(class_loader());
1373     {
1374       HandleMark hm(THREAD);
1375       Handle lockObject = compute_loader_lock_object(class_loader, THREAD);
1376       check_loader_lock_contention(lockObject, THREAD);
1377       ObjectLocker ol(lockObject, THREAD, true);
1378       // prohibited package check assumes all classes loaded from archive call
1379       // restore_unshareable_info which calls ik->set_package()
1380       ik->restore_unshareable_info(loader_data, protection_domain, CHECK_NULL);
1381     }
1382 
1383     ik->print_class_load_logging(loader_data, NULL, NULL);
1384 
1385     // For boot loader, ensure that GetSystemPackage knows that a class in this
1386     // package was loaded.
1387     if (class_loader.is_null()) {
1388       int path_index = ik->shared_classpath_index();
1389       ResourceMark rm;
1390       ClassLoader::add_package(ik->name()->as_C_string(), path_index, THREAD);
1391     }
1392 
1393     if (DumpLoadedClassList != NULL && classlist_file->is_open()) {
1394       // Only dump the classes that can be stored into CDS archive
1395       if (SystemDictionaryShared::is_sharing_possible(loader_data)) {
1396         ResourceMark rm(THREAD);
1397         classlist_file->print_cr("%s", ik->name()->as_C_string());
1398         classlist_file->flush();
1399       }
1400     }
1401 
1402     // notify a class loaded from shared object
1403     ClassLoadingService::notify_class_loaded(ik, true /* shared class */);
1404 
1405     ik->set_has_passed_fingerprint_check(false);
1406     if (UseAOT && ik->supers_have_passed_fingerprint_checks()) {
1407       uint64_t aot_fp = AOTLoader::get_saved_fingerprint(ik);
1408       uint64_t cds_fp = ik->get_stored_fingerprint();
1409       if (aot_fp != 0 && aot_fp == cds_fp) {
1410         // This class matches with a class saved in an AOT library
1411         ik->set_has_passed_fingerprint_check(true);
1412       } else {
1413         ResourceMark rm;
1414         log_info(class, fingerprint)("%s :  expected = " PTR64_FORMAT " actual = " PTR64_FORMAT, ik->external_name(), aot_fp, cds_fp);
1415       }
1416     }
1417   }
1418   return ik;
1419 }
1420 #endif // INCLUDE_CDS
1421 
1422 InstanceKlass* SystemDictionary::load_instance_class(Symbol* class_name, Handle class_loader, TRAPS) {
1423 
1424   if (class_loader.is_null()) {
1425     ResourceMark rm;
1426     PackageEntry* pkg_entry = NULL;
1427     bool search_only_bootloader_append = false;
1428     ClassLoaderData *loader_data = class_loader_data(class_loader);
1429 
1430     // Find the package in the boot loader's package entry table.
1431     TempNewSymbol pkg_name = InstanceKlass::package_from_name(class_name, CHECK_NULL);
1432     if (pkg_name != NULL) {
1433       pkg_entry = loader_data->packages()->lookup_only(pkg_name);
1434     }
1435 
1436     // Prior to attempting to load the class, enforce the boot loader's
1437     // visibility boundaries.
1438     if (!Universe::is_module_initialized()) {
1439       // During bootstrapping, prior to module initialization, any
1440       // class attempting to be loaded must be checked against the
1441       // java.base packages in the boot loader's PackageEntryTable.
1442       // No class outside of java.base is allowed to be loaded during
1443       // this bootstrapping window.
1444       if (pkg_entry == NULL || pkg_entry->in_unnamed_module()) {
1445         // Class is either in the unnamed package or in
1446         // a named package within the unnamed module.  Either
1447         // case is outside of java.base, do not attempt to
1448         // load the class post java.base definition.  If
1449         // java.base has not been defined, let the class load
1450         // and its package will be checked later by
1451         // ModuleEntryTable::verify_javabase_packages.
1452         if (ModuleEntryTable::javabase_defined()) {
1453           return NULL;
1454         }
1455       } else {
1456         // Check that the class' package is defined within java.base.
1457         ModuleEntry* mod_entry = pkg_entry->module();
1458         Symbol* mod_entry_name = mod_entry->name();
1459         if (mod_entry_name->fast_compare(vmSymbols::java_base()) != 0) {
1460           return NULL;
1461         }
1462       }
1463     } else {
1464       // After the module system has been initialized, check if the class'
1465       // package is in a module defined to the boot loader.
1466       if (pkg_name == NULL || pkg_entry == NULL || pkg_entry->in_unnamed_module()) {
1467         // Class is either in the unnamed package, in a named package
1468         // within a module not defined to the boot loader or in a
1469         // a named package within the unnamed module.  In all cases,
1470         // limit visibility to search for the class only in the boot
1471         // loader's append path.
1472         search_only_bootloader_append = true;
1473       }
1474     }
1475 
1476     // Prior to bootstrapping's module initialization, never load a class outside
1477     // of the boot loader's module path
1478     assert(Universe::is_module_initialized() ||
1479            !search_only_bootloader_append,
1480            "Attempt to load a class outside of boot loader's module path");
1481 
1482     // Search for classes in the CDS archive.
1483     InstanceKlass* k = NULL;
1484     {
1485 #if INCLUDE_CDS
1486       PerfTraceTime vmtimer(ClassLoader::perf_shared_classload_time());
1487       k = load_shared_boot_class(class_name, THREAD);
1488 #endif
1489     }
1490 
1491     if (k == NULL) {
1492       // Use VM class loader
1493       PerfTraceTime vmtimer(ClassLoader::perf_sys_classload_time());
1494       k = ClassLoader::load_class(class_name, search_only_bootloader_append, CHECK_NULL);
1495     }
1496 
1497     // find_or_define_instance_class may return a different InstanceKlass
1498     if (k != NULL) {
1499       InstanceKlass* defined_k =
1500         find_or_define_instance_class(class_name, class_loader, k, THREAD);
1501       if (!HAS_PENDING_EXCEPTION && defined_k != k) {
1502         // If a parallel capable class loader already defined this class, register 'k' for cleanup.
1503         assert(defined_k != NULL, "Should have a klass if there's no exception");
1504         loader_data->add_to_deallocate_list(k);
1505         k = defined_k;
1506       } else if (HAS_PENDING_EXCEPTION) {
1507         loader_data->add_to_deallocate_list(k);
1508         return NULL;
1509       }
1510     }
1511     return k;
1512   } else {
1513     // Use user specified class loader to load class. Call loadClass operation on class_loader.
1514     ResourceMark rm(THREAD);
1515 
1516     assert(THREAD->is_Java_thread(), "must be a JavaThread");
1517     JavaThread* jt = (JavaThread*) THREAD;
1518 
1519     PerfClassTraceTime vmtimer(ClassLoader::perf_app_classload_time(),
1520                                ClassLoader::perf_app_classload_selftime(),
1521                                ClassLoader::perf_app_classload_count(),
1522                                jt->get_thread_stat()->perf_recursion_counts_addr(),
1523                                jt->get_thread_stat()->perf_timers_addr(),
1524                                PerfClassTraceTime::CLASS_LOAD);
1525 
1526     Handle s = java_lang_String::create_from_symbol(class_name, CHECK_NULL);
1527     // Translate to external class name format, i.e., convert '/' chars to '.'
1528     Handle string = java_lang_String::externalize_classname(s, CHECK_NULL);
1529 
1530     JavaValue result(T_OBJECT);
1531 
1532     InstanceKlass* spec_klass = SystemDictionary::ClassLoader_klass();
1533 
1534     // Call public unsynchronized loadClass(String) directly for all class loaders.
1535     // For parallelCapable class loaders, JDK >=7, loadClass(String, boolean) will
1536     // acquire a class-name based lock rather than the class loader object lock.
1537     // JDK < 7 already acquire the class loader lock in loadClass(String, boolean).
1538     JavaCalls::call_virtual(&result,
1539                             class_loader,
1540                             spec_klass,
1541                             vmSymbols::loadClass_name(),
1542                             vmSymbols::string_class_signature(),
1543                             string,
1544                             CHECK_NULL);
1545 
1546     assert(result.get_type() == T_OBJECT, "just checking");
1547     oop obj = (oop) result.get_jobject();
1548 
1549     // Primitive classes return null since forName() can not be
1550     // used to obtain any of the Class objects representing primitives or void
1551     if ((obj != NULL) && !(java_lang_Class::is_primitive(obj))) {
1552       InstanceKlass* k = InstanceKlass::cast(java_lang_Class::as_Klass(obj));
1553       // For user defined Java class loaders, check that the name returned is
1554       // the same as that requested.  This check is done for the bootstrap
1555       // loader when parsing the class file.
1556       if (class_name == k->name()) {
1557         return k;
1558       }
1559     }
1560     // Class is not found or has the wrong name, return NULL
1561     return NULL;
1562   }
1563 }
1564 
1565 static void post_class_define_event(InstanceKlass* k, const ClassLoaderData* def_cld) {
1566   EventClassDefine event;
1567   if (event.should_commit()) {
1568     event.set_definedClass(k);
1569     event.set_definingClassLoader(def_cld);
1570     event.commit();
1571   }
1572 }
1573 
1574 void SystemDictionary::define_instance_class(InstanceKlass* k, TRAPS) {
1575 
1576   HandleMark hm(THREAD);
1577   ClassLoaderData* loader_data = k->class_loader_data();
1578   Handle class_loader_h(THREAD, loader_data->class_loader());
1579 
1580  // for bootstrap and other parallel classloaders don't acquire lock,
1581  // use placeholder token
1582  // If a parallelCapable class loader calls define_instance_class instead of
1583  // find_or_define_instance_class to get here, we have a timing
1584  // hole with systemDictionary updates and check_constraints
1585  if (!class_loader_h.is_null() && !is_parallelCapable(class_loader_h)) {
1586     assert(ObjectSynchronizer::current_thread_holds_lock((JavaThread*)THREAD,
1587          compute_loader_lock_object(class_loader_h, THREAD)),
1588          "define called without lock");
1589   }
1590 
1591   // Check class-loading constraints. Throw exception if violation is detected.
1592   // Grabs and releases SystemDictionary_lock
1593   // The check_constraints/find_class call and update_dictionary sequence
1594   // must be "atomic" for a specific class/classloader pair so we never
1595   // define two different instanceKlasses for that class/classloader pair.
1596   // Existing classloaders will call define_instance_class with the
1597   // classloader lock held
1598   // Parallel classloaders will call find_or_define_instance_class
1599   // which will require a token to perform the define class
1600   Symbol*  name_h = k->name();
1601   Dictionary* dictionary = loader_data->dictionary();
1602   unsigned int d_hash = dictionary->compute_hash(name_h);
1603   check_constraints(d_hash, k, class_loader_h, true, CHECK);
1604 
1605   // Register class just loaded with class loader (placed in Vector)
1606   // Note we do this before updating the dictionary, as this can
1607   // fail with an OutOfMemoryError (if it does, we will *not* put this
1608   // class in the dictionary and will not update the class hierarchy).
1609   // JVMTI FollowReferences needs to find the classes this way.
1610   if (k->class_loader() != NULL) {
1611     methodHandle m(THREAD, Universe::loader_addClass_method());
1612     JavaValue result(T_VOID);
1613     JavaCallArguments args(class_loader_h);
1614     args.push_oop(Handle(THREAD, k->java_mirror()));
1615     JavaCalls::call(&result, m, &args, CHECK);
1616   }
1617 
1618   // Add the new class. We need recompile lock during update of CHA.
1619   {
1620     unsigned int p_hash = placeholders()->compute_hash(name_h);
1621     int p_index = placeholders()->hash_to_index(p_hash);
1622 
1623     MutexLocker mu_r(Compile_lock, THREAD);
1624 
1625     // Add to class hierarchy, initialize vtables, and do possible
1626     // deoptimizations.
1627     add_to_hierarchy(k, CHECK); // No exception, but can block
1628 
1629     // Add to systemDictionary - so other classes can see it.
1630     // Grabs and releases SystemDictionary_lock
1631     update_dictionary(d_hash, p_index, p_hash,
1632                       k, class_loader_h, THREAD);
1633   }
1634   k->eager_initialize(THREAD);
1635 
1636   // notify jvmti
1637   if (JvmtiExport::should_post_class_load()) {
1638       assert(THREAD->is_Java_thread(), "thread->is_Java_thread()");
1639       JvmtiExport::post_class_load((JavaThread *) THREAD, k);
1640 
1641   }
1642   post_class_define_event(k, loader_data);
1643 }
1644 
1645 // Support parallel classloading
1646 // All parallel class loaders, including bootstrap classloader
1647 // lock a placeholder entry for this class/class_loader pair
1648 // to allow parallel defines of different classes for this class loader
1649 // With AllowParallelDefine flag==true, in case they do not synchronize around
1650 // FindLoadedClass/DefineClass, calls, we check for parallel
1651 // loading for them, wait if a defineClass is in progress
1652 // and return the initial requestor's results
1653 // This flag does not apply to the bootstrap classloader.
1654 // With AllowParallelDefine flag==false, call through to define_instance_class
1655 // which will throw LinkageError: duplicate class definition.
1656 // False is the requested default.
1657 // For better performance, the class loaders should synchronize
1658 // findClass(), i.e. FindLoadedClass/DefineClassIfAbsent or they
1659 // potentially waste time reading and parsing the bytestream.
1660 // Note: VM callers should ensure consistency of k/class_name,class_loader
1661 // Be careful when modifying this code: once you have run
1662 // placeholders()->find_and_add(PlaceholderTable::DEFINE_CLASS),
1663 // you need to find_and_remove it before returning.
1664 // So be careful to not exit with a CHECK_ macro betweeen these calls.
1665 InstanceKlass* SystemDictionary::find_or_define_instance_class(Symbol* class_name, Handle class_loader,
1666                                                                InstanceKlass* k, TRAPS) {
1667 
1668   Symbol*  name_h = k->name(); // passed in class_name may be null
1669   ClassLoaderData* loader_data = class_loader_data(class_loader);
1670   Dictionary* dictionary = loader_data->dictionary();
1671 
1672   unsigned int d_hash = dictionary->compute_hash(name_h);
1673 
1674   // Hold SD lock around find_class and placeholder creation for DEFINE_CLASS
1675   unsigned int p_hash = placeholders()->compute_hash(name_h);
1676   int p_index = placeholders()->hash_to_index(p_hash);
1677   PlaceholderEntry* probe;
1678 
1679   {
1680     MutexLocker mu(SystemDictionary_lock, THREAD);
1681     // First check if class already defined
1682     if (is_parallelDefine(class_loader)) {
1683       InstanceKlass* check = find_class(d_hash, name_h, dictionary);
1684       if (check != NULL) {
1685         return check;
1686       }
1687     }
1688 
1689     // Acquire define token for this class/classloader
1690     probe = placeholders()->find_and_add(p_index, p_hash, name_h, loader_data, PlaceholderTable::DEFINE_CLASS, NULL, THREAD);
1691     // Wait if another thread defining in parallel
1692     // All threads wait - even those that will throw duplicate class: otherwise
1693     // caller is surprised by LinkageError: duplicate, but findLoadedClass fails
1694     // if other thread has not finished updating dictionary
1695     while (probe->definer() != NULL) {
1696       SystemDictionary_lock->wait();
1697     }
1698     // Only special cases allow parallel defines and can use other thread's results
1699     // Other cases fall through, and may run into duplicate defines
1700     // caught by finding an entry in the SystemDictionary
1701     if (is_parallelDefine(class_loader) && (probe->instance_klass() != NULL)) {
1702         placeholders()->find_and_remove(p_index, p_hash, name_h, loader_data, PlaceholderTable::DEFINE_CLASS, THREAD);
1703         SystemDictionary_lock->notify_all();
1704 #ifdef ASSERT
1705         InstanceKlass* check = find_class(d_hash, name_h, dictionary);
1706         assert(check != NULL, "definer missed recording success");
1707 #endif
1708         return probe->instance_klass();
1709     } else {
1710       // This thread will define the class (even if earlier thread tried and had an error)
1711       probe->set_definer(THREAD);
1712     }
1713   }
1714 
1715   define_instance_class(k, THREAD);
1716 
1717   Handle linkage_exception = Handle(); // null handle
1718 
1719   // definer must notify any waiting threads
1720   {
1721     MutexLocker mu(SystemDictionary_lock, THREAD);
1722     PlaceholderEntry* probe = placeholders()->get_entry(p_index, p_hash, name_h, loader_data);
1723     assert(probe != NULL, "DEFINE_CLASS placeholder lost?");
1724     if (probe != NULL) {
1725       if (HAS_PENDING_EXCEPTION) {
1726         linkage_exception = Handle(THREAD,PENDING_EXCEPTION);
1727         CLEAR_PENDING_EXCEPTION;
1728       } else {
1729         probe->set_instance_klass(k);
1730       }
1731       probe->set_definer(NULL);
1732       placeholders()->find_and_remove(p_index, p_hash, name_h, loader_data, PlaceholderTable::DEFINE_CLASS, THREAD);
1733       SystemDictionary_lock->notify_all();
1734     }
1735   }
1736 
1737   // Can't throw exception while holding lock due to rank ordering
1738   if (linkage_exception() != NULL) {
1739     THROW_OOP_(linkage_exception(), NULL); // throws exception and returns
1740   }
1741 
1742   return k;
1743 }
1744 
1745 Handle SystemDictionary::compute_loader_lock_object(Handle class_loader, TRAPS) {
1746   // If class_loader is NULL we synchronize on _system_loader_lock_obj
1747   if (class_loader.is_null()) {
1748     return Handle(THREAD, _system_loader_lock_obj);
1749   } else {
1750     return class_loader;
1751   }
1752 }
1753 
1754 // This method is added to check how often we have to wait to grab loader
1755 // lock. The results are being recorded in the performance counters defined in
1756 // ClassLoader::_sync_systemLoaderLockContentionRate and
1757 // ClassLoader::_sync_nonSystemLoaderLockConteionRate.
1758 void SystemDictionary::check_loader_lock_contention(Handle loader_lock, TRAPS) {
1759   if (!UsePerfData) {
1760     return;
1761   }
1762 
1763   assert(!loader_lock.is_null(), "NULL lock object");
1764 
1765   if (ObjectSynchronizer::query_lock_ownership((JavaThread*)THREAD, loader_lock)
1766       == ObjectSynchronizer::owner_other) {
1767     // contention will likely happen, so increment the corresponding
1768     // contention counter.
1769     if (oopDesc::equals(loader_lock(), _system_loader_lock_obj)) {
1770       ClassLoader::sync_systemLoaderLockContentionRate()->inc();
1771     } else {
1772       ClassLoader::sync_nonSystemLoaderLockContentionRate()->inc();
1773     }
1774   }
1775 }
1776 
1777 // ----------------------------------------------------------------------------
1778 // Lookup
1779 
1780 InstanceKlass* SystemDictionary::find_class(unsigned int hash,
1781                                             Symbol* class_name,
1782                                             Dictionary* dictionary) {
1783   assert_locked_or_safepoint(SystemDictionary_lock);
1784   int index = dictionary->hash_to_index(hash);
1785   return dictionary->find_class(index, hash, class_name);
1786 }
1787 
1788 
1789 // Basic find on classes in the midst of being loaded
1790 Symbol* SystemDictionary::find_placeholder(Symbol* class_name,
1791                                            ClassLoaderData* loader_data) {
1792   assert_locked_or_safepoint(SystemDictionary_lock);
1793   unsigned int p_hash = placeholders()->compute_hash(class_name);
1794   int p_index = placeholders()->hash_to_index(p_hash);
1795   return placeholders()->find_entry(p_index, p_hash, class_name, loader_data);
1796 }
1797 
1798 
1799 // Used for assertions and verification only
1800 // Precalculating the hash and index is an optimization because there are many lookups
1801 // before adding the class.
1802 InstanceKlass* SystemDictionary::find_class(Symbol* class_name, ClassLoaderData* loader_data) {
1803   assert_locked_or_safepoint(SystemDictionary_lock);
1804   #ifndef ASSERT
1805   guarantee(VerifyBeforeGC      ||
1806             VerifyDuringGC      ||
1807             VerifyBeforeExit    ||
1808             VerifyDuringStartup ||
1809             VerifyAfterGC, "too expensive");
1810   #endif
1811 
1812   Dictionary* dictionary = loader_data->dictionary();
1813   unsigned int d_hash = dictionary->compute_hash(class_name);
1814   return find_class(d_hash, class_name, dictionary);
1815 }
1816 
1817 
1818 // ----------------------------------------------------------------------------
1819 // Update hierachy. This is done before the new klass has been added to the SystemDictionary. The Recompile_lock
1820 // is held, to ensure that the compiler is not using the class hierachy, and that deoptimization will kick in
1821 // before a new class is used.
1822 
1823 void SystemDictionary::add_to_hierarchy(InstanceKlass* k, TRAPS) {
1824   assert(k != NULL, "just checking");
1825   assert_locked_or_safepoint(Compile_lock);
1826 
1827   k->set_init_state(InstanceKlass::loaded);
1828   // make sure init_state store is already done.
1829   // The compiler reads the hierarchy outside of the Compile_lock.
1830   // Access ordering is used to add to hierarchy.
1831 
1832   // Link into hierachy.
1833   k->append_to_sibling_list();                    // add to superklass/sibling list
1834   k->process_interfaces(THREAD);                  // handle all "implements" declarations
1835 
1836   // Now flush all code that depended on old class hierarchy.
1837   // Note: must be done *after* linking k into the hierarchy (was bug 12/9/97)
1838   CodeCache::flush_dependents_on(k);
1839 }
1840 
1841 // ----------------------------------------------------------------------------
1842 // GC support
1843 
1844 // Assumes classes in the SystemDictionary are only unloaded at a safepoint
1845 // Note: anonymous classes are not in the SD.
1846 bool SystemDictionary::do_unloading(GCTimer* gc_timer) {
1847 
1848   bool unloading_occurred;
1849   bool is_concurrent = !SafepointSynchronize::is_at_safepoint();
1850   {
1851     GCTraceTime(Debug, gc, phases) t("ClassLoaderData", gc_timer);
1852     assert_locked_or_safepoint(ClassLoaderDataGraph_lock);  // caller locks.
1853     // First, mark for unload all ClassLoaderData referencing a dead class loader.
1854     unloading_occurred = ClassLoaderDataGraph::do_unloading();
1855     if (unloading_occurred) {
1856       MutexLockerEx ml2(is_concurrent ? Module_lock : NULL);
1857       JFR_ONLY(Jfr::on_unloading_classes();)
1858 
1859       MutexLockerEx ml1(is_concurrent ? SystemDictionary_lock : NULL);
1860       ClassLoaderDataGraph::clean_module_and_package_info();
1861       constraints()->purge_loader_constraints();
1862       resolution_errors()->purge_resolution_errors();
1863     }
1864   }
1865 
1866   GCTraceTime(Debug, gc, phases) t("Trigger cleanups", gc_timer);
1867   // Trigger cleaning the ResolvedMethodTable even if no unloading occurred.
1868   ResolvedMethodTable::trigger_cleanup();
1869 
1870   if (unloading_occurred) {
1871     SymbolTable::trigger_cleanup();
1872 
1873     // Oops referenced by the protection domain cache table may get unreachable independently
1874     // of the class loader (eg. cached protection domain oops). So we need to
1875     // explicitly unlink them here.
1876     // All protection domain oops are linked to the caller class, so if nothing
1877     // unloads, this is not needed.
1878     _pd_cache_table->trigger_cleanup();
1879   }
1880 
1881   return unloading_occurred;
1882 }
1883 
1884 void SystemDictionary::oops_do(OopClosure* f) {
1885   f->do_oop(&_java_system_loader);
1886   f->do_oop(&_java_platform_loader);
1887   f->do_oop(&_system_loader_lock_obj);
1888   CDS_ONLY(SystemDictionaryShared::oops_do(f);)
1889 
1890   // Visit extra methods
1891   invoke_method_table()->oops_do(f);
1892 }
1893 
1894 // CDS: scan and relocate all classes referenced by _well_known_klasses[].
1895 void SystemDictionary::well_known_klasses_do(MetaspaceClosure* it) {
1896   for (int id = FIRST_WKID; id < WKID_LIMIT; id++) {
1897     it->push(well_known_klass_addr((WKID)id));
1898   }
1899 }
1900 
1901 void SystemDictionary::methods_do(void f(Method*)) {
1902   // Walk methods in loaded classes
1903   MutexLocker ml(ClassLoaderDataGraph_lock);
1904   ClassLoaderDataGraph::methods_do(f);
1905   // Walk method handle intrinsics
1906   invoke_method_table()->methods_do(f);
1907 }
1908 
1909 // ----------------------------------------------------------------------------
1910 // Initialization
1911 
1912 void SystemDictionary::initialize(TRAPS) {
1913   // Allocate arrays
1914   _placeholders        = new PlaceholderTable(_placeholder_table_size);
1915   _number_of_modifications = 0;
1916   _loader_constraints  = new LoaderConstraintTable(_loader_constraint_size);
1917   _resolution_errors   = new ResolutionErrorTable(_resolution_error_size);
1918   _invoke_method_table = new SymbolPropertyTable(_invoke_method_size);
1919   _pd_cache_table = new ProtectionDomainCacheTable(defaultProtectionDomainCacheSize);
1920 
1921   // Allocate private object used as system class loader lock
1922   _system_loader_lock_obj = oopFactory::new_intArray(0, CHECK);
1923   // Initialize basic classes
1924   resolve_well_known_classes(CHECK);
1925 }
1926 
1927 // Compact table of directions on the initialization of klasses:
1928 static const short wk_init_info[] = {
1929   #define WK_KLASS_INIT_INFO(name, symbol) \
1930     ((short)vmSymbols::VM_SYMBOL_ENUM_NAME(symbol)),
1931 
1932   WK_KLASSES_DO(WK_KLASS_INIT_INFO)
1933   #undef WK_KLASS_INIT_INFO
1934   0
1935 };
1936 
1937 #ifdef ASSERT
1938 bool SystemDictionary::is_well_known_klass(Symbol* class_name) {
1939   int sid;
1940   for (int i = 0; (sid = wk_init_info[i]) != 0; i++) {
1941     Symbol* symbol = vmSymbols::symbol_at((vmSymbols::SID)sid);
1942     if (class_name == symbol) {
1943       return true;
1944     }
1945   }
1946   return false;
1947 }
1948 #endif
1949 
1950 bool SystemDictionary::resolve_wk_klass(WKID id, TRAPS) {
1951   assert(id >= (int)FIRST_WKID && id < (int)WKID_LIMIT, "oob");
1952   int sid = wk_init_info[id - FIRST_WKID];
1953   Symbol* symbol = vmSymbols::symbol_at((vmSymbols::SID)sid);
1954   InstanceKlass** klassp = &_well_known_klasses[id];
1955 
1956 
1957 #if INCLUDE_JVMCI
1958   if (id >= FIRST_JVMCI_WKID) {
1959     assert(EnableJVMCI, "resolve JVMCI classes only when EnableJVMCI is true");
1960   }
1961 #endif
1962 
1963   if ((*klassp) == NULL) {
1964     Klass* k = resolve_or_fail(symbol, true, CHECK_0);
1965     (*klassp) = InstanceKlass::cast(k);
1966   }
1967   return ((*klassp) != NULL);
1968 }
1969 
1970 void SystemDictionary::resolve_wk_klasses_until(WKID limit_id, WKID &start_id, TRAPS) {
1971   assert((int)start_id <= (int)limit_id, "IDs are out of order!");
1972   for (int id = (int)start_id; id < (int)limit_id; id++) {
1973     assert(id >= (int)FIRST_WKID && id < (int)WKID_LIMIT, "oob");
1974     resolve_wk_klass((WKID)id, CHECK);
1975   }
1976 
1977   // move the starting value forward to the limit:
1978   start_id = limit_id;
1979 }
1980 
1981 void SystemDictionary::resolve_well_known_classes(TRAPS) {
1982   assert(WK_KLASS(Object_klass) == NULL, "well-known classes should only be initialized once");
1983 
1984   // Create the ModuleEntry for java.base.  This call needs to be done here,
1985   // after vmSymbols::initialize() is called but before any classes are pre-loaded.
1986   ClassLoader::classLoader_init2(CHECK);
1987 
1988   // Preload commonly used klasses
1989   WKID scan = FIRST_WKID;
1990   // first do Object, then String, Class
1991 #if INCLUDE_CDS
1992   if (UseSharedSpaces) {
1993     resolve_wk_klasses_through(WK_KLASS_ENUM_NAME(Object_klass), scan, CHECK);
1994 
1995     // It's unsafe to access the archived heap regions before they
1996     // are fixed up, so we must do the fixup as early as possible
1997     // before the archived java objects are accessed by functions
1998     // such as java_lang_Class::restore_archived_mirror and
1999     // ConstantPool::restore_unshareable_info (restores the archived
2000     // resolved_references array object).
2001     //
2002     // HeapShared::fixup_mapped_heap_regions() fills the empty
2003     // spaces in the archived heap regions and may use
2004     // SystemDictionary::Object_klass(), so we can do this only after
2005     // Object_klass is resolved. See the above resolve_wk_klasses_through()
2006     // call. No mirror objects are accessed/restored in the above call.
2007     // Mirrors are restored after java.lang.Class is loaded.
2008     HeapShared::fixup_mapped_heap_regions();
2009 
2010     // Initialize the constant pool for the Object_class
2011     assert(Object_klass()->is_shared(), "must be");
2012     Object_klass()->constants()->restore_unshareable_info(CHECK);
2013     resolve_wk_klasses_through(WK_KLASS_ENUM_NAME(Class_klass), scan, CHECK);
2014   } else
2015 #endif
2016   {
2017     resolve_wk_klasses_through(WK_KLASS_ENUM_NAME(Class_klass), scan, CHECK);
2018   }
2019 
2020   // Calculate offsets for String and Class classes since they are loaded and
2021   // can be used after this point.
2022   java_lang_String::compute_offsets();
2023   java_lang_Class::compute_offsets();
2024 
2025   // Fixup mirrors for classes loaded before java.lang.Class.
2026   // These calls iterate over the objects currently in the perm gen
2027   // so calling them at this point is matters (not before when there
2028   // are fewer objects and not later after there are more objects
2029   // in the perm gen.
2030   Universe::initialize_basic_type_mirrors(CHECK);
2031   Universe::fixup_mirrors(CHECK);
2032 
2033   // do a bunch more:
2034   resolve_wk_klasses_through(WK_KLASS_ENUM_NAME(Reference_klass), scan, CHECK);
2035 
2036   // Preload ref klasses and set reference types
2037   InstanceKlass::cast(WK_KLASS(Reference_klass))->set_reference_type(REF_OTHER);
2038   InstanceRefKlass::update_nonstatic_oop_maps(WK_KLASS(Reference_klass));
2039 
2040   resolve_wk_klasses_through(WK_KLASS_ENUM_NAME(PhantomReference_klass), scan, CHECK);
2041   InstanceKlass::cast(WK_KLASS(SoftReference_klass))->set_reference_type(REF_SOFT);
2042   InstanceKlass::cast(WK_KLASS(WeakReference_klass))->set_reference_type(REF_WEAK);
2043   InstanceKlass::cast(WK_KLASS(FinalReference_klass))->set_reference_type(REF_FINAL);
2044   InstanceKlass::cast(WK_KLASS(PhantomReference_klass))->set_reference_type(REF_PHANTOM);
2045 
2046   // JSR 292 classes
2047   WKID jsr292_group_start = WK_KLASS_ENUM_NAME(MethodHandle_klass);
2048   WKID jsr292_group_end   = WK_KLASS_ENUM_NAME(VolatileCallSite_klass);
2049   resolve_wk_klasses_until(jsr292_group_start, scan, CHECK);
2050   resolve_wk_klasses_through(jsr292_group_end, scan, CHECK);
2051   WKID last = NOT_JVMCI(WKID_LIMIT) JVMCI_ONLY(FIRST_JVMCI_WKID);
2052   resolve_wk_klasses_until(last, scan, CHECK);
2053 
2054   _box_klasses[T_BOOLEAN] = WK_KLASS(Boolean_klass);
2055   _box_klasses[T_CHAR]    = WK_KLASS(Character_klass);
2056   _box_klasses[T_FLOAT]   = WK_KLASS(Float_klass);
2057   _box_klasses[T_DOUBLE]  = WK_KLASS(Double_klass);
2058   _box_klasses[T_BYTE]    = WK_KLASS(Byte_klass);
2059   _box_klasses[T_SHORT]   = WK_KLASS(Short_klass);
2060   _box_klasses[T_INT]     = WK_KLASS(Integer_klass);
2061   _box_klasses[T_LONG]    = WK_KLASS(Long_klass);
2062   //_box_klasses[T_OBJECT]  = WK_KLASS(object_klass);
2063   //_box_klasses[T_ARRAY]   = WK_KLASS(object_klass);
2064 
2065   { // Compute whether we should use checkPackageAccess or NOT
2066     Method* method = InstanceKlass::cast(ClassLoader_klass())->find_method(vmSymbols::checkPackageAccess_name(), vmSymbols::class_protectiondomain_signature());
2067     _has_checkPackageAccess = (method != NULL);
2068   }
2069 
2070 #ifdef ASSERT
2071   if (UseSharedSpaces) {
2072     assert(JvmtiExport::is_early_phase(),
2073            "All well known classes must be resolved in JVMTI early phase");
2074     for (int i = FIRST_WKID; i < last; i++) {
2075       InstanceKlass* k = _well_known_klasses[i];
2076       assert(k->is_shared(), "must not be replaced by JVMTI class file load hook");
2077     }
2078   }
2079 #endif
2080 }
2081 
2082 // Tells if a given klass is a box (wrapper class, such as java.lang.Integer).
2083 // If so, returns the basic type it holds.  If not, returns T_OBJECT.
2084 BasicType SystemDictionary::box_klass_type(Klass* k) {
2085   assert(k != NULL, "");
2086   for (int i = T_BOOLEAN; i < T_VOID+1; i++) {
2087     if (_box_klasses[i] == k)
2088       return (BasicType)i;
2089   }
2090   return T_OBJECT;
2091 }
2092 
2093 // Constraints on class loaders. The details of the algorithm can be
2094 // found in the OOPSLA'98 paper "Dynamic Class Loading in the Java
2095 // Virtual Machine" by Sheng Liang and Gilad Bracha.  The basic idea is
2096 // that the dictionary needs to maintain a set of contraints that
2097 // must be satisfied by all classes in the dictionary.
2098 // if defining is true, then LinkageError if already in dictionary
2099 // if initiating loader, then ok if InstanceKlass matches existing entry
2100 
2101 void SystemDictionary::check_constraints(unsigned int d_hash,
2102                                          InstanceKlass* k,
2103                                          Handle class_loader,
2104                                          bool defining,
2105                                          TRAPS) {
2106   ResourceMark rm(THREAD);
2107   stringStream ss;
2108   bool throwException = false;
2109 
2110   {
2111     Symbol *name = k->name();
2112     ClassLoaderData *loader_data = class_loader_data(class_loader);
2113 
2114     MutexLocker mu(SystemDictionary_lock, THREAD);
2115 
2116     InstanceKlass* check = find_class(d_hash, name, loader_data->dictionary());
2117     if (check != NULL) {
2118       // If different InstanceKlass - duplicate class definition,
2119       // else - ok, class loaded by a different thread in parallel.
2120       // We should only have found it if it was done loading and ok to use.
2121       // The dictionary only holds instance classes, placeholders
2122       // also hold array classes.
2123 
2124       assert(check->is_instance_klass(), "noninstance in systemdictionary");
2125       if ((defining == true) || (k != check)) {
2126         throwException = true;
2127         ss.print("loader %s", loader_data->loader_name_and_id());
2128         ss.print(" attempted duplicate %s definition for %s. (%s)",
2129                  k->external_kind(), k->external_name(), k->class_in_module_of_loader(false, true));
2130       } else {
2131         return;
2132       }
2133     }
2134 
2135 #ifdef ASSERT
2136     Symbol* ph_check = find_placeholder(name, loader_data);
2137     assert(ph_check == NULL || ph_check == name, "invalid symbol");
2138 #endif
2139 
2140     if (throwException == false) {
2141       if (constraints()->check_or_update(k, class_loader, name) == false) {
2142         throwException = true;
2143         ss.print("loader constraint violation: loader %s", loader_data->loader_name_and_id());
2144         ss.print(" wants to load %s %s.",
2145                  k->external_kind(), k->external_name());
2146         Klass *existing_klass = constraints()->find_constrained_klass(name, class_loader);
2147         if (existing_klass != NULL && existing_klass->class_loader() != class_loader()) {
2148           ss.print(" A different %s with the same name was previously loaded by %s. (%s)",
2149                    existing_klass->external_kind(),
2150                    existing_klass->class_loader_data()->loader_name_and_id(),
2151                    existing_klass->class_in_module_of_loader(false, true));
2152         } else {
2153           ss.print(" (%s)", k->class_in_module_of_loader(false, true));
2154         }
2155       }
2156     }
2157   }
2158 
2159   // Throw error now if needed (cannot throw while holding
2160   // SystemDictionary_lock because of rank ordering)
2161   if (throwException == true) {
2162     THROW_MSG(vmSymbols::java_lang_LinkageError(), ss.as_string());
2163   }
2164 }
2165 
2166 // Update class loader data dictionary - done after check_constraint and add_to_hierachy
2167 // have been called.
2168 void SystemDictionary::update_dictionary(unsigned int d_hash,
2169                                          int p_index, unsigned int p_hash,
2170                                          InstanceKlass* k,
2171                                          Handle class_loader,
2172                                          TRAPS) {
2173   // Compile_lock prevents systemDictionary updates during compilations
2174   assert_locked_or_safepoint(Compile_lock);
2175   Symbol*  name  = k->name();
2176   ClassLoaderData *loader_data = class_loader_data(class_loader);
2177 
2178   {
2179     MutexLocker mu1(SystemDictionary_lock, THREAD);
2180 
2181     // See whether biased locking is enabled and if so set it for this
2182     // klass.
2183     // Note that this must be done past the last potential blocking
2184     // point / safepoint. We enable biased locking lazily using a
2185     // VM_Operation to iterate the SystemDictionary and installing the
2186     // biasable mark word into each InstanceKlass's prototype header.
2187     // To avoid race conditions where we accidentally miss enabling the
2188     // optimization for one class in the process of being added to the
2189     // dictionary, we must not safepoint after the test of
2190     // BiasedLocking::enabled().
2191     if (UseBiasedLocking && BiasedLocking::enabled()) {
2192       // Set biased locking bit for all loaded classes; it will be
2193       // cleared if revocation occurs too often for this type
2194       // NOTE that we must only do this when the class is initally
2195       // defined, not each time it is referenced from a new class loader
2196       if (oopDesc::equals(k->class_loader(), class_loader())) {
2197         k->set_prototype_header(markOopDesc::biased_locking_prototype());
2198       }
2199     }
2200 
2201     // Make a new dictionary entry.
2202     Dictionary* dictionary = loader_data->dictionary();
2203     InstanceKlass* sd_check = find_class(d_hash, name, dictionary);
2204     if (sd_check == NULL) {
2205       dictionary->add_klass(d_hash, name, k);
2206 
2207       notice_modification();
2208     }
2209   #ifdef ASSERT
2210     sd_check = find_class(d_hash, name, dictionary);
2211     assert (sd_check != NULL, "should have entry in dictionary");
2212     // Note: there may be a placeholder entry: for circularity testing
2213     // or for parallel defines
2214   #endif
2215     SystemDictionary_lock->notify_all();
2216   }
2217 }
2218 
2219 
2220 // Try to find a class name using the loader constraints.  The
2221 // loader constraints might know about a class that isn't fully loaded
2222 // yet and these will be ignored.
2223 Klass* SystemDictionary::find_constrained_instance_or_array_klass(
2224                     Symbol* class_name, Handle class_loader, TRAPS) {
2225 
2226   // First see if it has been loaded directly.
2227   // Force the protection domain to be null.  (This removes protection checks.)
2228   Handle no_protection_domain;
2229   Klass* klass = find_instance_or_array_klass(class_name, class_loader,
2230                                               no_protection_domain, CHECK_NULL);
2231   if (klass != NULL)
2232     return klass;
2233 
2234   // Now look to see if it has been loaded elsewhere, and is subject to
2235   // a loader constraint that would require this loader to return the
2236   // klass that is already loaded.
2237   if (FieldType::is_array(class_name)) {
2238     // For array classes, their Klass*s are not kept in the
2239     // constraint table. The element Klass*s are.
2240     FieldArrayInfo fd;
2241     BasicType t = FieldType::get_array_info(class_name, fd, CHECK_(NULL));
2242     if (t != T_OBJECT) {
2243       klass = Universe::typeArrayKlassObj(t);
2244     } else {
2245       MutexLocker mu(SystemDictionary_lock, THREAD);
2246       klass = constraints()->find_constrained_klass(fd.object_key(), class_loader);
2247     }
2248     // If element class already loaded, allocate array klass
2249     if (klass != NULL) {
2250       klass = klass->array_klass_or_null(fd.dimension());
2251     }
2252   } else {
2253     MutexLocker mu(SystemDictionary_lock, THREAD);
2254     // Non-array classes are easy: simply check the constraint table.
2255     klass = constraints()->find_constrained_klass(class_name, class_loader);
2256   }
2257 
2258   return klass;
2259 }
2260 
2261 
2262 bool SystemDictionary::add_loader_constraint(Symbol* class_name,
2263                                              Handle class_loader1,
2264                                              Handle class_loader2,
2265                                              Thread* THREAD) {
2266   ClassLoaderData* loader_data1 = class_loader_data(class_loader1);
2267   ClassLoaderData* loader_data2 = class_loader_data(class_loader2);
2268 
2269   Symbol* constraint_name = NULL;
2270   // Needs to be in same scope as constraint_name in case a Symbol is created and
2271   // assigned to constraint_name.
2272   FieldArrayInfo fd;
2273   if (!FieldType::is_array(class_name)) {
2274     constraint_name = class_name;
2275   } else {
2276     // For array classes, their Klass*s are not kept in the
2277     // constraint table. The element classes are.
2278     BasicType t = FieldType::get_array_info(class_name, fd, CHECK_(false));
2279     // primitive types always pass
2280     if (t != T_OBJECT) {
2281       return true;
2282     } else {
2283       constraint_name = fd.object_key();
2284     }
2285   }
2286 
2287   Dictionary* dictionary1 = loader_data1->dictionary();
2288   unsigned int d_hash1 = dictionary1->compute_hash(constraint_name);
2289 
2290   Dictionary* dictionary2 = loader_data2->dictionary();
2291   unsigned int d_hash2 = dictionary2->compute_hash(constraint_name);
2292 
2293   {
2294     MutexLocker mu_s(SystemDictionary_lock, THREAD);
2295     InstanceKlass* klass1 = find_class(d_hash1, constraint_name, dictionary1);
2296     InstanceKlass* klass2 = find_class(d_hash2, constraint_name, dictionary2);
2297     return constraints()->add_entry(constraint_name, klass1, class_loader1,
2298                                     klass2, class_loader2);
2299   }
2300 }
2301 
2302 // Add entry to resolution error table to record the error when the first
2303 // attempt to resolve a reference to a class has failed.
2304 void SystemDictionary::add_resolution_error(const constantPoolHandle& pool, int which,
2305                                             Symbol* error, Symbol* message) {
2306   unsigned int hash = resolution_errors()->compute_hash(pool, which);
2307   int index = resolution_errors()->hash_to_index(hash);
2308   {
2309     MutexLocker ml(SystemDictionary_lock, Thread::current());
2310     resolution_errors()->add_entry(index, hash, pool, which, error, message);
2311   }
2312 }
2313 
2314 // Delete a resolution error for RedefineClasses for a constant pool is going away
2315 void SystemDictionary::delete_resolution_error(ConstantPool* pool) {
2316   resolution_errors()->delete_entry(pool);
2317 }
2318 
2319 // Lookup resolution error table. Returns error if found, otherwise NULL.
2320 Symbol* SystemDictionary::find_resolution_error(const constantPoolHandle& pool, int which,
2321                                                 Symbol** message) {
2322   unsigned int hash = resolution_errors()->compute_hash(pool, which);
2323   int index = resolution_errors()->hash_to_index(hash);
2324   {
2325     MutexLocker ml(SystemDictionary_lock, Thread::current());
2326     ResolutionErrorEntry* entry = resolution_errors()->find_entry(index, hash, pool, which);
2327     if (entry != NULL) {
2328       *message = entry->message();
2329       return entry->error();
2330     } else {
2331       return NULL;
2332     }
2333   }
2334 }
2335 
2336 
2337 // Signature constraints ensure that callers and callees agree about
2338 // the meaning of type names in their signatures.  This routine is the
2339 // intake for constraints.  It collects them from several places:
2340 //
2341 //  * LinkResolver::resolve_method (if check_access is true) requires
2342 //    that the resolving class (the caller) and the defining class of
2343 //    the resolved method (the callee) agree on each type in the
2344 //    method's signature.
2345 //
2346 //  * LinkResolver::resolve_interface_method performs exactly the same
2347 //    checks.
2348 //
2349 //  * LinkResolver::resolve_field requires that the constant pool
2350 //    attempting to link to a field agree with the field's defining
2351 //    class about the type of the field signature.
2352 //
2353 //  * klassVtable::initialize_vtable requires that, when a class
2354 //    overrides a vtable entry allocated by a superclass, that the
2355 //    overriding method (i.e., the callee) agree with the superclass
2356 //    on each type in the method's signature.
2357 //
2358 //  * klassItable::initialize_itable requires that, when a class fills
2359 //    in its itables, for each non-abstract method installed in an
2360 //    itable, the method (i.e., the callee) agree with the interface
2361 //    on each type in the method's signature.
2362 //
2363 // All those methods have a boolean (check_access, checkconstraints)
2364 // which turns off the checks.  This is used from specialized contexts
2365 // such as bootstrapping, dumping, and debugging.
2366 //
2367 // No direct constraint is placed between the class and its
2368 // supertypes.  Constraints are only placed along linked relations
2369 // between callers and callees.  When a method overrides or implements
2370 // an abstract method in a supertype (superclass or interface), the
2371 // constraints are placed as if the supertype were the caller to the
2372 // overriding method.  (This works well, since callers to the
2373 // supertype have already established agreement between themselves and
2374 // the supertype.)  As a result of all this, a class can disagree with
2375 // its supertype about the meaning of a type name, as long as that
2376 // class neither calls a relevant method of the supertype, nor is
2377 // called (perhaps via an override) from the supertype.
2378 //
2379 //
2380 // SystemDictionary::check_signature_loaders(sig, l1, l2)
2381 //
2382 // Make sure all class components (including arrays) in the given
2383 // signature will be resolved to the same class in both loaders.
2384 // Returns the name of the type that failed a loader constraint check, or
2385 // NULL if no constraint failed.  No exception except OOME is thrown.
2386 // Arrays are not added to the loader constraint table, their elements are.
2387 Symbol* SystemDictionary::check_signature_loaders(Symbol* signature,
2388                                                Handle loader1, Handle loader2,
2389                                                bool is_method, TRAPS)  {
2390   // Nothing to do if loaders are the same.
2391   if (oopDesc::equals(loader1(), loader2())) {
2392     return NULL;
2393   }
2394 
2395   SignatureStream sig_strm(signature, is_method);
2396   while (!sig_strm.is_done()) {
2397     if (sig_strm.is_object()) {
2398       Symbol* sig = sig_strm.as_symbol(CHECK_NULL);
2399       if (!add_loader_constraint(sig, loader1, loader2, THREAD)) {
2400         return sig;
2401       }
2402     }
2403     sig_strm.next();
2404   }
2405   return NULL;
2406 }
2407 
2408 
2409 methodHandle SystemDictionary::find_method_handle_intrinsic(vmIntrinsics::ID iid,
2410                                                             Symbol* signature,
2411                                                             TRAPS) {
2412   methodHandle empty;
2413   assert(MethodHandles::is_signature_polymorphic(iid) &&
2414          MethodHandles::is_signature_polymorphic_intrinsic(iid) &&
2415          iid != vmIntrinsics::_invokeGeneric,
2416          "must be a known MH intrinsic iid=%d: %s", iid, vmIntrinsics::name_at(iid));
2417 
2418   unsigned int hash  = invoke_method_table()->compute_hash(signature, iid);
2419   int          index = invoke_method_table()->hash_to_index(hash);
2420   SymbolPropertyEntry* spe = invoke_method_table()->find_entry(index, hash, signature, iid);
2421   methodHandle m;
2422   if (spe == NULL || spe->method() == NULL) {
2423     spe = NULL;
2424     // Must create lots of stuff here, but outside of the SystemDictionary lock.
2425     m = Method::make_method_handle_intrinsic(iid, signature, CHECK_(empty));
2426     if (!Arguments::is_interpreter_only()) {
2427       // Generate a compiled form of the MH intrinsic.
2428       AdapterHandlerLibrary::create_native_wrapper(m);
2429       // Check if have the compiled code.
2430       if (!m->has_compiled_code()) {
2431         THROW_MSG_(vmSymbols::java_lang_VirtualMachineError(),
2432                    "Out of space in CodeCache for method handle intrinsic", empty);
2433       }
2434     }
2435     // Now grab the lock.  We might have to throw away the new method,
2436     // if a racing thread has managed to install one at the same time.
2437     {
2438       MutexLocker ml(SystemDictionary_lock, THREAD);
2439       spe = invoke_method_table()->find_entry(index, hash, signature, iid);
2440       if (spe == NULL)
2441         spe = invoke_method_table()->add_entry(index, hash, signature, iid);
2442       if (spe->method() == NULL)
2443         spe->set_method(m());
2444     }
2445   }
2446 
2447   assert(spe != NULL && spe->method() != NULL, "");
2448   assert(Arguments::is_interpreter_only() || (spe->method()->has_compiled_code() &&
2449          spe->method()->code()->entry_point() == spe->method()->from_compiled_entry()),
2450          "MH intrinsic invariant");
2451   return spe->method();
2452 }
2453 
2454 // Helper for unpacking the return value from linkMethod and linkCallSite.
2455 static methodHandle unpack_method_and_appendix(Handle mname,
2456                                                Klass* accessing_klass,
2457                                                objArrayHandle appendix_box,
2458                                                Handle* appendix_result,
2459                                                TRAPS) {
2460   methodHandle empty;
2461   if (mname.not_null()) {
2462     Method* m = java_lang_invoke_MemberName::vmtarget(mname());
2463     if (m != NULL) {
2464       oop appendix = appendix_box->obj_at(0);
2465       if (TraceMethodHandles) {
2466     #ifndef PRODUCT
2467         ttyLocker ttyl;
2468         tty->print("Linked method=" INTPTR_FORMAT ": ", p2i(m));
2469         m->print();
2470         if (appendix != NULL) { tty->print("appendix = "); appendix->print(); }
2471         tty->cr();
2472     #endif //PRODUCT
2473       }
2474       (*appendix_result) = Handle(THREAD, appendix);
2475       // the target is stored in the cpCache and if a reference to this
2476       // MemberName is dropped we need a way to make sure the
2477       // class_loader containing this method is kept alive.
2478       ClassLoaderData* this_key = accessing_klass->class_loader_data();
2479       this_key->record_dependency(m->method_holder());
2480       return methodHandle(THREAD, m);
2481     }
2482   }
2483   THROW_MSG_(vmSymbols::java_lang_LinkageError(), "bad value from MethodHandleNatives", empty);
2484   return empty;
2485 }
2486 
2487 methodHandle SystemDictionary::find_method_handle_invoker(Klass* klass,
2488                                                           Symbol* name,
2489                                                           Symbol* signature,
2490                                                           Klass* accessing_klass,
2491                                                           Handle *appendix_result,
2492                                                           TRAPS) {
2493   methodHandle empty;
2494   assert(THREAD->can_call_java() ,"");
2495   Handle method_type =
2496     SystemDictionary::find_method_handle_type(signature, accessing_klass, CHECK_(empty));
2497 
2498   int ref_kind = JVM_REF_invokeVirtual;
2499   oop name_oop = StringTable::intern(name, CHECK_(empty));
2500   Handle name_str (THREAD, name_oop);
2501   objArrayHandle appendix_box = oopFactory::new_objArray_handle(SystemDictionary::Object_klass(), 1, CHECK_(empty));
2502   assert(appendix_box->obj_at(0) == NULL, "");
2503 
2504   // This should not happen.  JDK code should take care of that.
2505   if (accessing_klass == NULL || method_type.is_null()) {
2506     THROW_MSG_(vmSymbols::java_lang_InternalError(), "bad invokehandle", empty);
2507   }
2508 
2509   // call java.lang.invoke.MethodHandleNatives::linkMethod(... String, MethodType) -> MemberName
2510   JavaCallArguments args;
2511   args.push_oop(Handle(THREAD, accessing_klass->java_mirror()));
2512   args.push_int(ref_kind);
2513   args.push_oop(Handle(THREAD, klass->java_mirror()));
2514   args.push_oop(name_str);
2515   args.push_oop(method_type);
2516   args.push_oop(appendix_box);
2517   JavaValue result(T_OBJECT);
2518   JavaCalls::call_static(&result,
2519                          SystemDictionary::MethodHandleNatives_klass(),
2520                          vmSymbols::linkMethod_name(),
2521                          vmSymbols::linkMethod_signature(),
2522                          &args, CHECK_(empty));
2523   Handle mname(THREAD, (oop) result.get_jobject());
2524   return unpack_method_and_appendix(mname, accessing_klass, appendix_box, appendix_result, THREAD);
2525 }
2526 
2527 // Decide if we can globally cache a lookup of this class, to be returned to any client that asks.
2528 // We must ensure that all class loaders everywhere will reach this class, for any client.
2529 // This is a safe bet for public classes in java.lang, such as Object and String.
2530 // We also include public classes in java.lang.invoke, because they appear frequently in system-level method types.
2531 // Out of an abundance of caution, we do not include any other classes, not even for packages like java.util.
2532 static bool is_always_visible_class(oop mirror) {
2533   Klass* klass = java_lang_Class::as_Klass(mirror);
2534   if (klass->is_objArray_klass()) {
2535     klass = ObjArrayKlass::cast(klass)->bottom_klass(); // check element type
2536   }
2537   if (klass->is_typeArray_klass()) {
2538     return true; // primitive array
2539   }
2540   assert(klass->is_instance_klass(), "%s", klass->external_name());
2541   return klass->is_public() &&
2542          (InstanceKlass::cast(klass)->is_same_class_package(SystemDictionary::Object_klass()) ||       // java.lang
2543           InstanceKlass::cast(klass)->is_same_class_package(SystemDictionary::MethodHandle_klass()));  // java.lang.invoke
2544 }
2545 
2546 
2547 // Return the Java mirror (java.lang.Class instance) for a single-character
2548 // descriptor.  This result, when available, is the same as produced by the
2549 // heavier API point of the same name that takes a Symbol.
2550 oop SystemDictionary::find_java_mirror_for_type(char signature_char) {
2551   return java_lang_Class::primitive_mirror(char2type(signature_char));
2552 }
2553 
2554 // Find or construct the Java mirror (java.lang.Class instance) for a
2555 // for the given field type signature, as interpreted relative to the
2556 // given class loader.  Handles primitives, void, references, arrays,
2557 // and all other reflectable types, except method types.
2558 // N.B.  Code in reflection should use this entry point.
2559 Handle SystemDictionary::find_java_mirror_for_type(Symbol* signature,
2560                                                    Klass* accessing_klass,
2561                                                    Handle class_loader,
2562                                                    Handle protection_domain,
2563                                                    SignatureStream::FailureMode failure_mode,
2564                                                    TRAPS) {
2565   Handle empty;
2566 
2567   assert(accessing_klass == NULL || (class_loader.is_null() && protection_domain.is_null()),
2568          "one or the other, or perhaps neither");
2569 
2570   Symbol* type = signature;
2571 
2572   // What we have here must be a valid field descriptor,
2573   // and all valid field descriptors are supported.
2574   // Produce the same java.lang.Class that reflection reports.
2575   if (type->utf8_length() == 1) {
2576 
2577     // It's a primitive.  (Void has a primitive mirror too.)
2578     char ch = type->char_at(0);
2579     assert(is_java_primitive(char2type(ch)) || ch == 'V', "");
2580     return Handle(THREAD, find_java_mirror_for_type(ch));
2581 
2582   } else if (FieldType::is_obj(type) || FieldType::is_array(type)) {
2583 
2584     // It's a reference type.
2585     if (accessing_klass != NULL) {
2586       class_loader      = Handle(THREAD, accessing_klass->class_loader());
2587       protection_domain = Handle(THREAD, accessing_klass->protection_domain());
2588     }
2589     Klass* constant_type_klass;
2590     if (failure_mode == SignatureStream::ReturnNull) {
2591       constant_type_klass = resolve_or_null(type, class_loader, protection_domain,
2592                                             CHECK_(empty));
2593     } else {
2594       bool throw_error = (failure_mode == SignatureStream::NCDFError);
2595       constant_type_klass = resolve_or_fail(type, class_loader, protection_domain,
2596                                             throw_error, CHECK_(empty));
2597     }
2598     if (constant_type_klass == NULL) {
2599       return Handle();  // report failure this way
2600     }
2601     Handle mirror(THREAD, constant_type_klass->java_mirror());
2602 
2603     // Check accessibility, emulating ConstantPool::verify_constant_pool_resolve.
2604     if (accessing_klass != NULL) {
2605       Klass* sel_klass = constant_type_klass;
2606       bool fold_type_to_class = true;
2607       LinkResolver::check_klass_accessability(accessing_klass, sel_klass,
2608                                               fold_type_to_class, CHECK_(empty));
2609     }
2610 
2611     return mirror;
2612 
2613   }
2614 
2615   // Fall through to an error.
2616   assert(false, "unsupported mirror syntax");
2617   THROW_MSG_(vmSymbols::java_lang_InternalError(), "unsupported mirror syntax", empty);
2618 }
2619 
2620 
2621 // Ask Java code to find or construct a java.lang.invoke.MethodType for the given
2622 // signature, as interpreted relative to the given class loader.
2623 // Because of class loader constraints, all method handle usage must be
2624 // consistent with this loader.
2625 Handle SystemDictionary::find_method_handle_type(Symbol* signature,
2626                                                  Klass* accessing_klass,
2627                                                  TRAPS) {
2628   Handle empty;
2629   vmIntrinsics::ID null_iid = vmIntrinsics::_none;  // distinct from all method handle invoker intrinsics
2630   unsigned int hash  = invoke_method_table()->compute_hash(signature, null_iid);
2631   int          index = invoke_method_table()->hash_to_index(hash);
2632   SymbolPropertyEntry* spe = invoke_method_table()->find_entry(index, hash, signature, null_iid);
2633   if (spe != NULL && spe->method_type() != NULL) {
2634     assert(java_lang_invoke_MethodType::is_instance(spe->method_type()), "");
2635     return Handle(THREAD, spe->method_type());
2636   } else if (!THREAD->can_call_java()) {
2637     warning("SystemDictionary::find_method_handle_type called from compiler thread");  // FIXME
2638     return Handle();  // do not attempt from within compiler, unless it was cached
2639   }
2640 
2641   Handle class_loader, protection_domain;
2642   if (accessing_klass != NULL) {
2643     class_loader      = Handle(THREAD, accessing_klass->class_loader());
2644     protection_domain = Handle(THREAD, accessing_klass->protection_domain());
2645   }
2646   bool can_be_cached = true;
2647   int npts = ArgumentCount(signature).size();
2648   objArrayHandle pts = oopFactory::new_objArray_handle(SystemDictionary::Class_klass(), npts, CHECK_(empty));
2649   int arg = 0;
2650   Handle rt; // the return type from the signature
2651   ResourceMark rm(THREAD);
2652   for (SignatureStream ss(signature); !ss.is_done(); ss.next()) {
2653     oop mirror = NULL;
2654     if (can_be_cached) {
2655       // Use neutral class loader to lookup candidate classes to be placed in the cache.
2656       mirror = ss.as_java_mirror(Handle(), Handle(),
2657                                  SignatureStream::ReturnNull, CHECK_(empty));
2658       if (mirror == NULL || (ss.is_object() && !is_always_visible_class(mirror))) {
2659         // Fall back to accessing_klass context.
2660         can_be_cached = false;
2661       }
2662     }
2663     if (!can_be_cached) {
2664       // Resolve, throwing a real error if it doesn't work.
2665       mirror = ss.as_java_mirror(class_loader, protection_domain,
2666                                  SignatureStream::NCDFError, CHECK_(empty));
2667     }
2668     assert(mirror != NULL, "%s", ss.as_symbol(THREAD)->as_C_string());
2669     if (ss.at_return_type())
2670       rt = Handle(THREAD, mirror);
2671     else
2672       pts->obj_at_put(arg++, mirror);
2673 
2674     // Check accessibility.
2675     if (!java_lang_Class::is_primitive(mirror) && accessing_klass != NULL) {
2676       Klass* sel_klass = java_lang_Class::as_Klass(mirror);
2677       mirror = NULL;  // safety
2678       // Emulate ConstantPool::verify_constant_pool_resolve.
2679       bool fold_type_to_class = true;
2680       LinkResolver::check_klass_accessability(accessing_klass, sel_klass,
2681                                               fold_type_to_class, CHECK_(empty));
2682     }
2683   }
2684   assert(arg == npts, "");
2685 
2686   // call java.lang.invoke.MethodHandleNatives::findMethodHandleType(Class rt, Class[] pts) -> MethodType
2687   JavaCallArguments args(Handle(THREAD, rt()));
2688   args.push_oop(pts);
2689   JavaValue result(T_OBJECT);
2690   JavaCalls::call_static(&result,
2691                          SystemDictionary::MethodHandleNatives_klass(),
2692                          vmSymbols::findMethodHandleType_name(),
2693                          vmSymbols::findMethodHandleType_signature(),
2694                          &args, CHECK_(empty));
2695   Handle method_type(THREAD, (oop) result.get_jobject());
2696 
2697   if (can_be_cached) {
2698     // We can cache this MethodType inside the JVM.
2699     MutexLocker ml(SystemDictionary_lock, THREAD);
2700     spe = invoke_method_table()->find_entry(index, hash, signature, null_iid);
2701     if (spe == NULL)
2702       spe = invoke_method_table()->add_entry(index, hash, signature, null_iid);
2703     if (spe->method_type() == NULL) {
2704       spe->set_method_type(method_type());
2705     }
2706   }
2707 
2708   // report back to the caller with the MethodType
2709   return method_type;
2710 }
2711 
2712 Handle SystemDictionary::find_field_handle_type(Symbol* signature,
2713                                                 Klass* accessing_klass,
2714                                                 TRAPS) {
2715   Handle empty;
2716   ResourceMark rm(THREAD);
2717   SignatureStream ss(signature, /*is_method=*/ false);
2718   if (!ss.is_done()) {
2719     Handle class_loader, protection_domain;
2720     if (accessing_klass != NULL) {
2721       class_loader      = Handle(THREAD, accessing_klass->class_loader());
2722       protection_domain = Handle(THREAD, accessing_klass->protection_domain());
2723     }
2724     oop mirror = ss.as_java_mirror(class_loader, protection_domain, SignatureStream::NCDFError, CHECK_(empty));
2725     ss.next();
2726     if (ss.is_done()) {
2727       return Handle(THREAD, mirror);
2728     }
2729   }
2730   return empty;
2731 }
2732 
2733 // Ask Java code to find or construct a method handle constant.
2734 Handle SystemDictionary::link_method_handle_constant(Klass* caller,
2735                                                      int ref_kind, //e.g., JVM_REF_invokeVirtual
2736                                                      Klass* callee,
2737                                                      Symbol* name,
2738                                                      Symbol* signature,
2739                                                      TRAPS) {
2740   Handle empty;
2741   if (caller == NULL) {
2742     THROW_MSG_(vmSymbols::java_lang_InternalError(), "bad MH constant", empty);
2743   }
2744   Handle name_str      = java_lang_String::create_from_symbol(name,      CHECK_(empty));
2745   Handle signature_str = java_lang_String::create_from_symbol(signature, CHECK_(empty));
2746 
2747   // Put symbolic info from the MH constant into freshly created MemberName and resolve it.
2748   Handle mname = MemberName_klass()->allocate_instance_handle(CHECK_(empty));
2749   java_lang_invoke_MemberName::set_clazz(mname(), callee->java_mirror());
2750   java_lang_invoke_MemberName::set_name (mname(), name_str());
2751   java_lang_invoke_MemberName::set_type (mname(), signature_str());
2752   java_lang_invoke_MemberName::set_flags(mname(), MethodHandles::ref_kind_to_flags(ref_kind));
2753 
2754   if (ref_kind == JVM_REF_invokeVirtual &&
2755       MethodHandles::is_signature_polymorphic_public_name(callee, name)) {
2756     // Skip resolution for public signature polymorphic methods such as
2757     // j.l.i.MethodHandle.invoke()/invokeExact() and those on VarHandle
2758     // They require appendix argument which MemberName resolution doesn't handle.
2759     // There's special logic on JDK side to handle them
2760     // (see MethodHandles.linkMethodHandleConstant() and MethodHandles.findVirtualForMH()).
2761   } else {
2762     MethodHandles::resolve_MemberName(mname, caller, /*speculative_resolve*/false, CHECK_(empty));
2763   }
2764 
2765   // After method/field resolution succeeded, it's safe to resolve MH signature as well.
2766   Handle type = MethodHandles::resolve_MemberName_type(mname, caller, CHECK_(empty));
2767 
2768   // call java.lang.invoke.MethodHandleNatives::linkMethodHandleConstant(Class caller, int refKind, Class callee, String name, Object type) -> MethodHandle
2769   JavaCallArguments args;
2770   args.push_oop(Handle(THREAD, caller->java_mirror()));  // the referring class
2771   args.push_int(ref_kind);
2772   args.push_oop(Handle(THREAD, callee->java_mirror()));  // the target class
2773   args.push_oop(name_str);
2774   args.push_oop(type);
2775   JavaValue result(T_OBJECT);
2776   JavaCalls::call_static(&result,
2777                          SystemDictionary::MethodHandleNatives_klass(),
2778                          vmSymbols::linkMethodHandleConstant_name(),
2779                          vmSymbols::linkMethodHandleConstant_signature(),
2780                          &args, CHECK_(empty));
2781   return Handle(THREAD, (oop) result.get_jobject());
2782 }
2783 
2784 // Ask Java to compute a constant by invoking a BSM given a Dynamic_info CP entry
2785 Handle SystemDictionary::link_dynamic_constant(Klass* caller,
2786                                                int condy_index,
2787                                                Handle bootstrap_specifier,
2788                                                Symbol* name,
2789                                                Symbol* type,
2790                                                TRAPS) {
2791   Handle empty;
2792   Handle bsm, info;
2793   if (java_lang_invoke_MethodHandle::is_instance(bootstrap_specifier())) {
2794     bsm = bootstrap_specifier;
2795   } else {
2796     assert(bootstrap_specifier->is_objArray(), "");
2797     objArrayOop args = (objArrayOop) bootstrap_specifier();
2798     assert(args->length() == 2, "");
2799     bsm  = Handle(THREAD, args->obj_at(0));
2800     info = Handle(THREAD, args->obj_at(1));
2801   }
2802   guarantee(java_lang_invoke_MethodHandle::is_instance(bsm()),
2803             "caller must supply a valid BSM");
2804 
2805   // This should not happen.  JDK code should take care of that.
2806   if (caller == NULL) {
2807     THROW_MSG_(vmSymbols::java_lang_InternalError(), "bad dynamic constant", empty);
2808   }
2809 
2810   Handle constant_name = java_lang_String::create_from_symbol(name, CHECK_(empty));
2811 
2812   // Resolve the constant type in the context of the caller class
2813   Handle type_mirror = find_java_mirror_for_type(type, caller, SignatureStream::NCDFError,
2814                                                  CHECK_(empty));
2815 
2816   // call java.lang.invoke.MethodHandleNatives::linkConstantDyanmic(caller, condy_index, bsm, type, info)
2817   JavaCallArguments args;
2818   args.push_oop(Handle(THREAD, caller->java_mirror()));
2819   args.push_int(condy_index);
2820   args.push_oop(bsm);
2821   args.push_oop(constant_name);
2822   args.push_oop(type_mirror);
2823   args.push_oop(info);
2824   JavaValue result(T_OBJECT);
2825   JavaCalls::call_static(&result,
2826                          SystemDictionary::MethodHandleNatives_klass(),
2827                          vmSymbols::linkDynamicConstant_name(),
2828                          vmSymbols::linkDynamicConstant_signature(),
2829                          &args, CHECK_(empty));
2830 
2831   return Handle(THREAD, (oop) result.get_jobject());
2832 }
2833 
2834 // Ask Java code to find or construct a java.lang.invoke.CallSite for the given
2835 // name and signature, as interpreted relative to the given class loader.
2836 methodHandle SystemDictionary::find_dynamic_call_site_invoker(Klass* caller,
2837                                                               int indy_index,
2838                                                               Handle bootstrap_specifier,
2839                                                               Symbol* name,
2840                                                               Symbol* type,
2841                                                               Handle *appendix_result,
2842                                                               TRAPS) {
2843   methodHandle empty;
2844   Handle bsm, info;
2845   if (java_lang_invoke_MethodHandle::is_instance(bootstrap_specifier())) {
2846     bsm = bootstrap_specifier;
2847   } else {
2848     objArrayOop args = (objArrayOop) bootstrap_specifier();
2849     assert(args->length() == 2, "");
2850     bsm  = Handle(THREAD, args->obj_at(0));
2851     info = Handle(THREAD, args->obj_at(1));
2852   }
2853   guarantee(java_lang_invoke_MethodHandle::is_instance(bsm()),
2854             "caller must supply a valid BSM");
2855 
2856   Handle method_name = java_lang_String::create_from_symbol(name, CHECK_(empty));
2857   Handle method_type = find_method_handle_type(type, caller, CHECK_(empty));
2858 
2859   // This should not happen.  JDK code should take care of that.
2860   if (caller == NULL || method_type.is_null()) {
2861     THROW_MSG_(vmSymbols::java_lang_InternalError(), "bad invokedynamic", empty);
2862   }
2863 
2864   objArrayHandle appendix_box = oopFactory::new_objArray_handle(SystemDictionary::Object_klass(), 1, CHECK_(empty));
2865   assert(appendix_box->obj_at(0) == NULL, "");
2866 
2867   // call java.lang.invoke.MethodHandleNatives::linkCallSite(caller, indy_index, bsm, name, mtype, info, &appendix)
2868   JavaCallArguments args;
2869   args.push_oop(Handle(THREAD, caller->java_mirror()));
2870   args.push_int(indy_index);
2871   args.push_oop(bsm);
2872   args.push_oop(method_name);
2873   args.push_oop(method_type);
2874   args.push_oop(info);
2875   args.push_oop(appendix_box);
2876   JavaValue result(T_OBJECT);
2877   JavaCalls::call_static(&result,
2878                          SystemDictionary::MethodHandleNatives_klass(),
2879                          vmSymbols::linkCallSite_name(),
2880                          vmSymbols::linkCallSite_signature(),
2881                          &args, CHECK_(empty));
2882   Handle mname(THREAD, (oop) result.get_jobject());
2883   return unpack_method_and_appendix(mname, caller, appendix_box, appendix_result, THREAD);
2884 }
2885 
2886 // Protection domain cache table handling
2887 
2888 ProtectionDomainCacheEntry* SystemDictionary::cache_get(Handle protection_domain) {
2889   return _pd_cache_table->get(protection_domain);
2890 }
2891 
2892 // ----------------------------------------------------------------------------
2893 
2894 void SystemDictionary::print_on(outputStream *st) {
2895   CDS_ONLY(SystemDictionaryShared::print_on(st));
2896   GCMutexLocker mu(SystemDictionary_lock);
2897 
2898   ClassLoaderDataGraph::print_dictionary(st);
2899 
2900   // Placeholders
2901   placeholders()->print_on(st);
2902   st->cr();
2903 
2904   // loader constraints - print under SD_lock
2905   constraints()->print_on(st);
2906   st->cr();
2907 
2908   _pd_cache_table->print_on(st);
2909   st->cr();
2910 }
2911 
2912 void SystemDictionary::verify() {
2913   guarantee(constraints() != NULL,
2914             "Verify of loader constraints failed");
2915   guarantee(placeholders()->number_of_entries() >= 0,
2916             "Verify of placeholders failed");
2917 
2918   GCMutexLocker mu(SystemDictionary_lock);
2919 
2920   // Verify dictionary
2921   ClassLoaderDataGraph::verify_dictionary();
2922 
2923   placeholders()->verify();
2924 
2925   // Verify constraint table
2926   guarantee(constraints() != NULL, "Verify of loader constraints failed");
2927   constraints()->verify(placeholders());
2928 
2929   _pd_cache_table->verify();
2930 }
2931 
2932 void SystemDictionary::dump(outputStream *st, bool verbose) {
2933   assert_locked_or_safepoint(SystemDictionary_lock);
2934   if (verbose) {
2935     print_on(st);
2936   } else {
2937     CDS_ONLY(SystemDictionaryShared::print_table_statistics(st));
2938     ClassLoaderDataGraph::print_dictionary_statistics(st);
2939     placeholders()->print_table_statistics(st, "Placeholder Table");
2940     constraints()->print_table_statistics(st, "LoaderConstraints Table");
2941     _pd_cache_table->print_table_statistics(st, "ProtectionDomainCache Table");
2942   }
2943 }
2944 
2945 // Utility for dumping dictionaries.
2946 SystemDictionaryDCmd::SystemDictionaryDCmd(outputStream* output, bool heap) :
2947                                  DCmdWithParser(output, heap),
2948   _verbose("-verbose", "Dump the content of each dictionary entry for all class loaders",
2949            "BOOLEAN", false, "false") {
2950   _dcmdparser.add_dcmd_option(&_verbose);
2951 }
2952 
2953 void SystemDictionaryDCmd::execute(DCmdSource source, TRAPS) {
2954   VM_DumpHashtable dumper(output(), VM_DumpHashtable::DumpSysDict,
2955                          _verbose.value());
2956   VMThread::execute(&dumper);
2957 }
2958 
2959 int SystemDictionaryDCmd::num_arguments() {
2960   ResourceMark rm;
2961   SystemDictionaryDCmd* dcmd = new SystemDictionaryDCmd(NULL, false);
2962   if (dcmd != NULL) {
2963     DCmdMark mark(dcmd);
2964     return dcmd->_dcmdparser.num_arguments();
2965   } else {
2966     return 0;
2967   }
2968 }
2969 
2970 void SystemDictionary::initialize_oop_storage() {
2971   _vm_weak_oop_storage =
2972     new OopStorage("VM Weak Oop Handles",
2973                    VMWeakAlloc_lock,
2974                    VMWeakActive_lock);
2975 }
2976 
2977 OopStorage* SystemDictionary::vm_weak_oop_storage() {
2978   assert(_vm_weak_oop_storage != NULL, "Uninitialized");
2979   return _vm_weak_oop_storage;
2980 }