1 /* 2 * Copyright (c) 2016, Oracle and/or its affiliates. All rights reserved. 3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. 4 * 5 * This code is free software; you can redistribute it and/or modify it 6 * under the terms of the GNU General Public License version 2 only, as 7 * published by the Free Software Foundation. 8 * 9 * This code is distributed in the hope that it will be useful, but WITHOUT 10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 12 * version 2 for more details (a copy is included in the LICENSE file that 13 * accompanied this code). 14 * 15 * You should have received a copy of the GNU General Public License version 16 * 2 along with this work; if not, write to the Free Software Foundation, 17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. 18 * 19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA 20 * or visit www.oracle.com if you need additional information or have any 21 * questions. 22 * 23 */ 24 25 #include "precompiled.hpp" 26 #include "classfile/classLoaderData.hpp" 27 #include "classfile/javaClasses.hpp" 28 #include "classfile/moduleEntry.hpp" 29 #include "logging/log.hpp" 30 #include "memory/resourceArea.hpp" 31 #include "oops/symbol.hpp" 32 #include "prims/jni.h" 33 #include "runtime/handles.inline.hpp" 34 #include "runtime/safepoint.hpp" 35 #include "trace/traceMacros.hpp" 36 #include "utilities/events.hpp" 37 #include "utilities/growableArray.hpp" 38 #include "utilities/hashtable.inline.hpp" 39 #include "utilities/ostream.hpp" 40 41 ModuleEntry* ModuleEntryTable::_javabase_module = NULL; 42 43 void ModuleEntry::set_location(Symbol* location) { 44 if (_location != NULL) { 45 // _location symbol's refcounts are managed by ModuleEntry, 46 // must decrement the old one before updating. 47 _location->decrement_refcount(); 48 } 49 50 _location = location; 51 52 if (location != NULL) { 53 location->increment_refcount(); 54 } 55 } 56 57 bool ModuleEntry::is_non_jdk_module() { 58 ResourceMark rm; 59 if (location() != NULL) { 60 const char* loc = location()->as_C_string(); 61 if (strncmp(loc, "jrt:/java.", 10) != 0 && strncmp(loc, "jrt:/jdk.", 9) != 0) { 62 return true; 63 } 64 } 65 return false; 66 } 67 68 void ModuleEntry::set_version(Symbol* version) { 69 if (_version != NULL) { 70 // _version symbol's refcounts are managed by ModuleEntry, 71 // must decrement the old one before updating. 72 _version->decrement_refcount(); 73 } 74 75 _version = version; 76 77 if (version != NULL) { 78 version->increment_refcount(); 79 } 80 } 81 82 // Returns the shared ProtectionDomain 83 Handle ModuleEntry::shared_protection_domain() { 84 return Handle(JNIHandles::resolve(_pd)); 85 } 86 87 // Set the shared ProtectionDomain atomically 88 void ModuleEntry::set_shared_protection_domain(ClassLoaderData *loader_data, 89 Handle pd_h) { 90 // Create a JNI handle for the shared ProtectionDomain and save it atomically. 91 // If someone beats us setting the _pd cache, the created JNI handle is destroyed. 92 jobject obj = loader_data->add_handle(pd_h); 93 if (Atomic::cmpxchg_ptr(obj, &_pd, NULL) != NULL) { 94 loader_data->remove_handle(obj); 95 } 96 } 97 98 // Returns true if this module can read module m 99 bool ModuleEntry::can_read(ModuleEntry* m) const { 100 assert(m != NULL, "No module to lookup in this module's reads list"); 101 102 // Unnamed modules read everyone and all modules 103 // read java.base. If either of these conditions 104 // hold, readability has been established. 105 if (!this->is_named() || 106 (m == ModuleEntryTable::javabase_moduleEntry())) { 107 return true; 108 } 109 110 MutexLocker m1(Module_lock); 111 if (!has_reads()) { 112 return false; 113 } else { 114 return _reads->contains(m); 115 } 116 } 117 118 // Add a new module to this module's reads list 119 void ModuleEntry::add_read(ModuleEntry* m) { 120 MutexLocker m1(Module_lock); 121 if (m == NULL) { 122 set_can_read_all_unnamed(); 123 } else { 124 if (_reads == NULL) { 125 // Lazily create a module's reads list 126 _reads = new (ResourceObj::C_HEAP, mtModule)GrowableArray<ModuleEntry*>(MODULE_READS_SIZE, true); 127 } 128 129 // Determine, based on this newly established read edge to module m, 130 // if this module's read list should be walked at a GC safepoint. 131 set_read_walk_required(m->loader_data()); 132 133 // Establish readability to module m 134 _reads->append_if_missing(m); 135 } 136 } 137 138 // If the module's loader, that a read edge is being established to, is 139 // not the same loader as this module's and is not one of the 3 builtin 140 // class loaders, then this module's reads list must be walked at GC 141 // safepoint. Modules have the same life cycle as their defining class 142 // loaders and should be removed if dead. 143 void ModuleEntry::set_read_walk_required(ClassLoaderData* m_loader_data) { 144 assert_locked_or_safepoint(Module_lock); 145 if (!_must_walk_reads && 146 loader_data() != m_loader_data && 147 !m_loader_data->is_builtin_class_loader_data()) { 148 _must_walk_reads = true; 149 if (log_is_enabled(Trace, modules)) { 150 ResourceMark rm; 151 log_trace(modules)("ModuleEntry::set_read_walk_required(): module %s reads list must be walked", 152 (name() != NULL) ? name()->as_C_string() : UNNAMED_MODULE); 153 } 154 } 155 } 156 157 bool ModuleEntry::has_reads() const { 158 assert_locked_or_safepoint(Module_lock); 159 return ((_reads != NULL) && !_reads->is_empty()); 160 } 161 162 // Purge dead module entries out of reads list. 163 void ModuleEntry::purge_reads() { 164 assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint"); 165 166 if (_must_walk_reads && has_reads()) { 167 // This module's _must_walk_reads flag will be reset based 168 // on the remaining live modules on the reads list. 169 _must_walk_reads = false; 170 171 if (log_is_enabled(Trace, modules)) { 172 ResourceMark rm; 173 log_trace(modules)("ModuleEntry::purge_reads(): module %s reads list being walked", 174 (name() != NULL) ? name()->as_C_string() : UNNAMED_MODULE); 175 } 176 177 // Go backwards because this removes entries that are dead. 178 int len = _reads->length(); 179 for (int idx = len - 1; idx >= 0; idx--) { 180 ModuleEntry* module_idx = _reads->at(idx); 181 ClassLoaderData* cld_idx = module_idx->loader_data(); 182 if (cld_idx->is_unloading()) { 183 _reads->delete_at(idx); 184 } else { 185 // Update the need to walk this module's reads based on live modules 186 set_read_walk_required(cld_idx); 187 } 188 } 189 } 190 } 191 192 void ModuleEntry::module_reads_do(ModuleClosure* const f) { 193 assert_locked_or_safepoint(Module_lock); 194 assert(f != NULL, "invariant"); 195 196 if (has_reads()) { 197 int reads_len = _reads->length(); 198 for (int i = 0; i < reads_len; ++i) { 199 f->do_module(_reads->at(i)); 200 } 201 } 202 } 203 204 void ModuleEntry::delete_reads() { 205 assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint"); 206 delete _reads; 207 _reads = NULL; 208 } 209 210 ModuleEntryTable::ModuleEntryTable(int table_size) 211 : Hashtable<Symbol*, mtModule>(table_size, sizeof(ModuleEntry)), _unnamed_module(NULL) 212 { 213 } 214 215 ModuleEntryTable::~ModuleEntryTable() { 216 assert_locked_or_safepoint(Module_lock); 217 218 // Walk through all buckets and all entries in each bucket, 219 // freeing each entry. 220 for (int i = 0; i < table_size(); ++i) { 221 for (ModuleEntry* m = bucket(i); m != NULL;) { 222 ModuleEntry* to_remove = m; 223 // read next before freeing. 224 m = m->next(); 225 226 ResourceMark rm; 227 log_debug(modules)("ModuleEntryTable: deleting module: %s", to_remove->name() != NULL ? 228 to_remove->name()->as_C_string() : UNNAMED_MODULE); 229 230 // Clean out the C heap allocated reads list first before freeing the entry 231 to_remove->delete_reads(); 232 if (to_remove->name() != NULL) { 233 to_remove->name()->decrement_refcount(); 234 } 235 if (to_remove->version() != NULL) { 236 to_remove->version()->decrement_refcount(); 237 } 238 if (to_remove->location() != NULL) { 239 to_remove->location()->decrement_refcount(); 240 } 241 242 // Unlink from the Hashtable prior to freeing 243 unlink_entry(to_remove); 244 FREE_C_HEAP_ARRAY(char, to_remove); 245 } 246 } 247 assert(number_of_entries() == 0, "should have removed all entries"); 248 assert(new_entry_free_list() == NULL, "entry present on ModuleEntryTable's free list"); 249 free_buckets(); 250 } 251 252 void ModuleEntryTable::create_unnamed_module(ClassLoaderData* loader_data) { 253 assert(Module_lock->owned_by_self(), "should have the Module_lock"); 254 255 // Each ModuleEntryTable has exactly one unnamed module 256 if (loader_data->is_the_null_class_loader_data()) { 257 // For the boot loader, the java.lang.reflect.Module for the unnamed module 258 // is not known until a call to JVM_SetBootLoaderUnnamedModule is made. At 259 // this point initially create the ModuleEntry for the unnamed module. 260 _unnamed_module = new_entry(0, Handle(NULL), NULL, NULL, NULL, loader_data); 261 } else { 262 // For all other class loaders the java.lang.reflect.Module for their 263 // corresponding unnamed module can be found in the java.lang.ClassLoader object. 264 oop module = java_lang_ClassLoader::unnamedModule(loader_data->class_loader()); 265 _unnamed_module = new_entry(0, Handle(module), NULL, NULL, NULL, loader_data); 266 267 // Store pointer to the ModuleEntry in the unnamed module's java.lang.reflect.Module 268 // object. 269 java_lang_reflect_Module::set_module_entry(module, _unnamed_module); 270 } 271 272 // Add to bucket 0, no name to hash on 273 add_entry(0, _unnamed_module); 274 } 275 276 ModuleEntry* ModuleEntryTable::new_entry(unsigned int hash, Handle module_handle, Symbol* name, 277 Symbol* version, Symbol* location, 278 ClassLoaderData* loader_data) { 279 assert(Module_lock->owned_by_self(), "should have the Module_lock"); 280 ModuleEntry* entry = (ModuleEntry*) NEW_C_HEAP_ARRAY(char, entry_size(), mtModule); 281 282 // Initialize everything BasicHashtable would 283 entry->set_next(NULL); 284 entry->set_hash(hash); 285 entry->set_literal(name); 286 287 // Initialize fields specific to a ModuleEntry 288 entry->init(); 289 if (name != NULL) { 290 name->increment_refcount(); 291 } else { 292 // Unnamed modules can read all other unnamed modules. 293 entry->set_can_read_all_unnamed(); 294 } 295 296 if (!module_handle.is_null()) { 297 entry->set_module(loader_data->add_handle(module_handle)); 298 } 299 300 entry->set_loader_data(loader_data); 301 entry->set_version(version); 302 entry->set_location(location); 303 304 TRACE_INIT_ID(entry); 305 306 return entry; 307 } 308 309 void ModuleEntryTable::add_entry(int index, ModuleEntry* new_entry) { 310 assert(Module_lock->owned_by_self(), "should have the Module_lock"); 311 Hashtable<Symbol*, mtModule>::add_entry(index, (HashtableEntry<Symbol*, mtModule>*)new_entry); 312 } 313 314 ModuleEntry* ModuleEntryTable::locked_create_entry_or_null(Handle module_handle, 315 Symbol* module_name, 316 Symbol* module_version, 317 Symbol* module_location, 318 ClassLoaderData* loader_data) { 319 assert(module_name != NULL, "ModuleEntryTable locked_create_entry_or_null should never be called for unnamed module."); 320 assert(Module_lock->owned_by_self(), "should have the Module_lock"); 321 // Check if module already exists. 322 if (lookup_only(module_name) != NULL) { 323 return NULL; 324 } else { 325 ModuleEntry* entry = new_entry(compute_hash(module_name), module_handle, module_name, 326 module_version, module_location, loader_data); 327 add_entry(index_for(module_name), entry); 328 return entry; 329 } 330 } 331 332 // lookup_only by Symbol* to find a ModuleEntry. 333 ModuleEntry* ModuleEntryTable::lookup_only(Symbol* name) { 334 if (name == NULL) { 335 // Return this table's unnamed module 336 return unnamed_module(); 337 } 338 int index = index_for(name); 339 for (ModuleEntry* m = bucket(index); m != NULL; m = m->next()) { 340 if (m->name()->fast_compare(name) == 0) { 341 return m; 342 } 343 } 344 return NULL; 345 } 346 347 // Remove dead modules from all other alive modules' reads list. 348 // This should only occur at class unloading. 349 void ModuleEntryTable::purge_all_module_reads() { 350 assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint"); 351 for (int i = 0; i < table_size(); i++) { 352 for (ModuleEntry* entry = bucket(i); 353 entry != NULL; 354 entry = entry->next()) { 355 entry->purge_reads(); 356 } 357 } 358 } 359 360 void ModuleEntryTable::finalize_javabase(Handle module_handle, Symbol* version, Symbol* location) { 361 assert(Module_lock->owned_by_self(), "should have the Module_lock"); 362 ClassLoaderData* boot_loader_data = ClassLoaderData::the_null_class_loader_data(); 363 ModuleEntryTable* module_table = boot_loader_data->modules(); 364 365 assert(module_table != NULL, "boot loader's ModuleEntryTable not defined"); 366 367 if (module_handle.is_null()) { 368 fatal("Unable to finalize module definition for java.base"); 369 } 370 371 // Set java.lang.reflect.Module, version and location for java.base 372 ModuleEntry* jb_module = javabase_moduleEntry(); 373 assert(jb_module != NULL, "java.base ModuleEntry not defined"); 374 jb_module->set_version(version); 375 jb_module->set_location(location); 376 // Once java.base's ModuleEntry _module field is set with the known 377 // java.lang.reflect.Module, java.base is considered "defined" to the VM. 378 jb_module->set_module(boot_loader_data->add_handle(module_handle)); 379 380 // Store pointer to the ModuleEntry for java.base in the java.lang.reflect.Module object. 381 java_lang_reflect_Module::set_module_entry(module_handle(), jb_module); 382 } 383 384 // Within java.lang.Class instances there is a java.lang.reflect.Module field 385 // that must be set with the defining module. During startup, prior to java.base's 386 // definition, classes needing their module field set are added to the fixup_module_list. 387 // Their module field is set once java.base's java.lang.reflect.Module is known to the VM. 388 void ModuleEntryTable::patch_javabase_entries(Handle module_handle) { 389 if (module_handle.is_null()) { 390 fatal("Unable to patch the module field of classes loaded prior to java.base's definition, invalid java.lang.reflect.Module"); 391 } 392 393 // Do the fixups for the basic primitive types 394 java_lang_Class::set_module(Universe::int_mirror(), module_handle()); 395 java_lang_Class::set_module(Universe::float_mirror(), module_handle()); 396 java_lang_Class::set_module(Universe::double_mirror(), module_handle()); 397 java_lang_Class::set_module(Universe::byte_mirror(), module_handle()); 398 java_lang_Class::set_module(Universe::bool_mirror(), module_handle()); 399 java_lang_Class::set_module(Universe::char_mirror(), module_handle()); 400 java_lang_Class::set_module(Universe::long_mirror(), module_handle()); 401 java_lang_Class::set_module(Universe::short_mirror(), module_handle()); 402 java_lang_Class::set_module(Universe::void_mirror(), module_handle()); 403 404 // Do the fixups for classes that have already been created. 405 GrowableArray <Klass*>* list = java_lang_Class::fixup_module_field_list(); 406 int list_length = list->length(); 407 for (int i = 0; i < list_length; i++) { 408 Klass* k = list->at(i); 409 assert(k->is_klass(), "List should only hold classes"); 410 java_lang_Class::fixup_module_field(KlassHandle(k), module_handle); 411 k->class_loader_data()->dec_keep_alive(); 412 } 413 414 delete java_lang_Class::fixup_module_field_list(); 415 java_lang_Class::set_fixup_module_field_list(NULL); 416 } 417 418 void ModuleEntryTable::print(outputStream* st) { 419 st->print_cr("Module Entry Table (table_size=%d, entries=%d)", 420 table_size(), number_of_entries()); 421 for (int i = 0; i < table_size(); i++) { 422 for (ModuleEntry* probe = bucket(i); 423 probe != NULL; 424 probe = probe->next()) { 425 probe->print(st); 426 } 427 } 428 } 429 430 void ModuleEntry::print(outputStream* st) { 431 ResourceMark rm; 432 st->print_cr("entry " PTR_FORMAT " name %s module " PTR_FORMAT " loader %s version %s location %s strict %s next " PTR_FORMAT, 433 p2i(this), 434 name() == NULL ? UNNAMED_MODULE : name()->as_C_string(), 435 p2i(module()), 436 loader_data()->loader_name(), 437 version() != NULL ? version()->as_C_string() : "NULL", 438 location() != NULL ? location()->as_C_string() : "NULL", 439 BOOL_TO_STR(!can_read_all_unnamed()), p2i(next())); 440 } 441 442 void ModuleEntryTable::verify() { 443 int element_count = 0; 444 for (int i = 0; i < table_size(); i++) { 445 for (ModuleEntry* probe = bucket(i); 446 probe != NULL; 447 probe = probe->next()) { 448 probe->verify(); 449 element_count++; 450 } 451 } 452 guarantee(number_of_entries() == element_count, 453 "Verify of Module Entry Table failed"); 454 DEBUG_ONLY(verify_lookup_length((double)number_of_entries() / table_size(), "Module Entry Table")); 455 } 456 457 void ModuleEntry::verify() { 458 guarantee(loader_data() != NULL, "A module entry must be associated with a loader."); 459 }