1 /* 2 * Copyright (c) 2003, 2017, 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/dictionary.hpp" 27 #include "classfile/classLoaderData.inline.hpp" 28 #include "classfile/loaderConstraints.hpp" 29 #include "memory/resourceArea.hpp" 30 #include "oops/oop.inline.hpp" 31 #include "runtime/handles.inline.hpp" 32 #include "runtime/safepoint.hpp" 33 #include "utilities/hashtable.inline.hpp" 34 35 void LoaderConstraintEntry::set_loader(int i, oop p) { 36 set_loader_data(i, ClassLoaderData::class_loader_data(p)); 37 } 38 39 LoaderConstraintTable::LoaderConstraintTable(int table_size) 40 : Hashtable<InstanceKlass*, mtClass>(table_size, sizeof(LoaderConstraintEntry)) {}; 41 42 43 LoaderConstraintEntry* LoaderConstraintTable::new_entry( 44 unsigned int hash, Symbol* name, 45 InstanceKlass* klass, int num_loaders, 46 int max_loaders) { 47 LoaderConstraintEntry* entry; 48 entry = (LoaderConstraintEntry*)Hashtable<InstanceKlass*, mtClass>::new_entry(hash, klass); 49 entry->set_name(name); 50 entry->set_num_loaders(num_loaders); 51 entry->set_max_loaders(max_loaders); 52 return entry; 53 } 54 55 void LoaderConstraintTable::free_entry(LoaderConstraintEntry *entry) { 56 // decrement name refcount before freeing 57 entry->name()->decrement_refcount(); 58 Hashtable<InstanceKlass*, mtClass>::free_entry(entry); 59 } 60 61 // The loaderConstraintTable must always be accessed with the 62 // SystemDictionary lock held. This is true even for readers as 63 // entries in the table could be being dynamically resized. 64 65 LoaderConstraintEntry** LoaderConstraintTable::find_loader_constraint( 66 Symbol* name, Handle loader) { 67 68 unsigned int hash = compute_hash(name); 69 int index = hash_to_index(hash); 70 LoaderConstraintEntry** pp = bucket_addr(index); 71 ClassLoaderData* loader_data = ClassLoaderData::class_loader_data(loader()); 72 73 while (*pp) { 74 LoaderConstraintEntry* p = *pp; 75 if (p->hash() == hash) { 76 if (p->name() == name) { 77 for (int i = p->num_loaders() - 1; i >= 0; i--) { 78 if (p->loader_data(i) == loader_data) { 79 return pp; 80 } 81 } 82 } 83 } 84 pp = p->next_addr(); 85 } 86 return pp; 87 } 88 89 90 void LoaderConstraintTable::purge_loader_constraints() { 91 assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint"); 92 // Remove unloaded entries from constraint table 93 for (int index = 0; index < table_size(); index++) { 94 LoaderConstraintEntry** p = bucket_addr(index); 95 while(*p) { 96 LoaderConstraintEntry* probe = *p; 97 InstanceKlass* klass = probe->klass(); 98 // Remove klass that is no longer alive 99 if (klass != NULL && 100 klass->class_loader_data()->is_unloading()) { 101 probe->set_klass(NULL); 102 if (log_is_enabled(Info, class, loader, constraints)) { 103 ResourceMark rm; 104 outputStream* out = Log(class, loader, constraints)::info_stream(); 105 out->print_cr("purging class object from constraint for name %s," 106 " loader list:", 107 probe->name()->as_C_string()); 108 for (int i = 0; i < probe->num_loaders(); i++) { 109 out->print_cr(" [%d]: %s", i, 110 probe->loader_data(i)->loader_name()); 111 } 112 } 113 } 114 // Remove entries no longer alive from loader array 115 int n = 0; 116 while (n < probe->num_loaders()) { 117 if (probe->loader_data(n)->is_unloading()) { 118 if (log_is_enabled(Info, class, loader, constraints)) { 119 ResourceMark rm; 120 outputStream* out = Log(class, loader, constraints)::info_stream(); 121 out->print_cr("purging loader %s from constraint for name %s", 122 probe->loader_data(n)->loader_name(), 123 probe->name()->as_C_string() 124 ); 125 } 126 127 // Compact array 128 int num = probe->num_loaders() - 1; 129 probe->set_num_loaders(num); 130 probe->set_loader_data(n, probe->loader_data(num)); 131 probe->set_loader_data(num, NULL); 132 133 if (log_is_enabled(Info, class, loader, constraints)) { 134 ResourceMark rm; 135 outputStream* out = Log(class, loader, constraints)::info_stream(); 136 out->print_cr("new loader list:"); 137 for (int i = 0; i < probe->num_loaders(); i++) { 138 out->print_cr(" [%d]: %s", i, 139 probe->loader_data(i)->loader_name()); 140 } 141 } 142 143 continue; // current element replaced, so restart without 144 // incrementing n 145 } 146 n++; 147 } 148 // Check whether entry should be purged 149 if (probe->num_loaders() < 2) { 150 if (log_is_enabled(Info, class, loader, constraints)) { 151 ResourceMark rm; 152 outputStream* out = Log(class, loader, constraints)::info_stream(); 153 out->print_cr("purging complete constraint for name %s", 154 probe->name()->as_C_string()); 155 } 156 157 // Purge entry 158 *p = probe->next(); 159 FREE_C_HEAP_ARRAY(oop, probe->loaders()); 160 free_entry(probe); 161 } else { 162 #ifdef ASSERT 163 if (probe->klass() != NULL) { 164 ClassLoaderData* loader_data = 165 probe->klass()->class_loader_data(); 166 assert(!loader_data->is_unloading(), "klass should be live"); 167 } 168 #endif 169 // Go to next entry 170 p = probe->next_addr(); 171 } 172 } 173 } 174 } 175 176 void log_ldr_constraint_msg(Symbol* class_name, const char* reason, 177 Handle class_loader1, Handle class_loader2) { 178 if (log_is_enabled(Info, class, loader, constraints)) { 179 ResourceMark rm; 180 outputStream* out = Log(class, loader, constraints)::info_stream(); 181 out->print_cr("Failed to add constraint for name: %s, loader[0]: %s," 182 " loader[1]: %s, Reason: %s", 183 class_name->as_C_string(), 184 SystemDictionary::loader_name(class_loader1()), 185 SystemDictionary::loader_name(class_loader2()), 186 reason); 187 } 188 } 189 190 bool LoaderConstraintTable::add_entry(Symbol* class_name, 191 InstanceKlass* klass1, Handle class_loader1, 192 InstanceKlass* klass2, Handle class_loader2) { 193 if (klass1 != NULL && klass2 != NULL) { 194 if (klass1 == klass2) { 195 // Same type already loaded in both places. There is no need for any constraint. 196 return true; 197 } else { 198 log_ldr_constraint_msg(class_name, 199 "The class objects presented by loader[0] and loader[1] " 200 "are different", 201 class_loader1, class_loader2); 202 return false; 203 } 204 } 205 206 InstanceKlass* klass = klass1 != NULL ? klass1 : klass2; 207 LoaderConstraintEntry** pp1 = find_loader_constraint(class_name, class_loader1); 208 if (*pp1 != NULL && (*pp1)->klass() != NULL) { 209 if (klass != NULL) { 210 if (klass != (*pp1)->klass()) { 211 log_ldr_constraint_msg(class_name, 212 "The class object presented by loader[0] does not match " 213 "the stored class object in the constraint", 214 class_loader1, class_loader2); 215 return false; 216 } 217 } else { 218 klass = (*pp1)->klass(); 219 } 220 } 221 222 LoaderConstraintEntry** pp2 = find_loader_constraint(class_name, class_loader2); 223 if (*pp2 != NULL && (*pp2)->klass() != NULL) { 224 if (klass != NULL) { 225 if (klass != (*pp2)->klass()) { 226 log_ldr_constraint_msg(class_name, 227 "The class object presented by loader[1] does not match " 228 "the stored class object in the constraint", 229 class_loader1, class_loader2); 230 return false; 231 } 232 } else { 233 klass = (*pp2)->klass(); 234 } 235 } 236 237 if (*pp1 == NULL && *pp2 == NULL) { 238 unsigned int hash = compute_hash(class_name); 239 int index = hash_to_index(hash); 240 LoaderConstraintEntry* p; 241 p = new_entry(hash, class_name, klass, 2, 2); 242 p->set_loaders(NEW_C_HEAP_ARRAY(ClassLoaderData*, 2, mtClass)); 243 p->set_loader(0, class_loader1()); 244 p->set_loader(1, class_loader2()); 245 p->set_klass(klass); 246 p->set_next(bucket(index)); 247 set_entry(index, p); 248 if (log_is_enabled(Info, class, loader, constraints)) { 249 ResourceMark rm; 250 outputStream* out = Log(class, loader, constraints)::info_stream(); 251 out->print_cr("adding new constraint for name: %s, loader[0]: %s," 252 " loader[1]: %s", 253 class_name->as_C_string(), 254 SystemDictionary::loader_name(class_loader1()), 255 SystemDictionary::loader_name(class_loader2()) 256 ); 257 } 258 } else if (*pp1 == *pp2) { 259 /* constraint already imposed */ 260 if ((*pp1)->klass() == NULL) { 261 (*pp1)->set_klass(klass); 262 if (log_is_enabled(Info, class, loader, constraints)) { 263 ResourceMark rm; 264 outputStream* out = Log(class, loader, constraints)::info_stream(); 265 out->print_cr("setting class object in existing constraint for" 266 " name: %s and loader %s", 267 class_name->as_C_string(), 268 SystemDictionary::loader_name(class_loader1()) 269 ); 270 } 271 } else { 272 assert((*pp1)->klass() == klass, "loader constraints corrupted"); 273 } 274 } else if (*pp1 == NULL) { 275 extend_loader_constraint(*pp2, class_loader1, klass); 276 } else if (*pp2 == NULL) { 277 extend_loader_constraint(*pp1, class_loader2, klass); 278 } else { 279 merge_loader_constraints(pp1, pp2, klass); 280 } 281 282 return true; 283 } 284 285 286 // return true if the constraint was updated, false if the constraint is 287 // violated 288 bool LoaderConstraintTable::check_or_update(InstanceKlass* k, 289 Handle loader, 290 Symbol* name) { 291 LoaderConstraintEntry* p = *(find_loader_constraint(name, loader)); 292 if (p && p->klass() != NULL && p->klass() != k) { 293 if (log_is_enabled(Info, class, loader, constraints)) { 294 ResourceMark rm; 295 outputStream* out = Log(class, loader, constraints)::info_stream(); 296 out->print_cr("constraint check failed for name %s, loader %s: " 297 "the presented class object differs from that stored", 298 name->as_C_string(), 299 SystemDictionary::loader_name(loader())); 300 } 301 return false; 302 } else { 303 if (p && p->klass() == NULL) { 304 p->set_klass(k); 305 if (log_is_enabled(Info, class, loader, constraints)) { 306 ResourceMark rm; 307 outputStream* out = Log(class, loader, constraints)::info_stream(); 308 out->print_cr("updating constraint for name %s, loader %s, " 309 "by setting class object", 310 name->as_C_string(), 311 SystemDictionary::loader_name(loader())); 312 } 313 } 314 return true; 315 } 316 } 317 318 InstanceKlass* LoaderConstraintTable::find_constrained_klass(Symbol* name, 319 Handle loader) { 320 LoaderConstraintEntry *p = *(find_loader_constraint(name, loader)); 321 if (p != NULL && p->klass() != NULL) { 322 assert(p->klass()->is_instance_klass(), "sanity"); 323 if (p->klass()->is_loaded()) { 324 // Only return fully loaded classes. Classes found through the 325 // constraints might still be in the process of loading. 326 return NULL; 327 } 328 return p->klass(); 329 } 330 331 // No constraints, or else no klass loaded yet. 332 return NULL; 333 } 334 335 void LoaderConstraintTable::ensure_loader_constraint_capacity( 336 LoaderConstraintEntry *p, 337 int nfree) { 338 if (p->max_loaders() - p->num_loaders() < nfree) { 339 int n = nfree + p->num_loaders(); 340 ClassLoaderData** new_loaders = NEW_C_HEAP_ARRAY(ClassLoaderData*, n, mtClass); 341 memcpy(new_loaders, p->loaders(), sizeof(ClassLoaderData*) * p->num_loaders()); 342 p->set_max_loaders(n); 343 FREE_C_HEAP_ARRAY(ClassLoaderData*, p->loaders()); 344 p->set_loaders(new_loaders); 345 } 346 } 347 348 349 void LoaderConstraintTable::extend_loader_constraint(LoaderConstraintEntry* p, 350 Handle loader, 351 InstanceKlass* klass) { 352 ensure_loader_constraint_capacity(p, 1); 353 int num = p->num_loaders(); 354 p->set_loader(num, loader()); 355 p->set_num_loaders(num + 1); 356 if (log_is_enabled(Info, class, loader, constraints)) { 357 ResourceMark rm; 358 outputStream* out = Log(class, loader, constraints)::info_stream(); 359 out->print_cr("extending constraint for name %s by adding loader[%d]: %s %s", 360 p->name()->as_C_string(), 361 num, 362 SystemDictionary::loader_name(loader()), 363 (p->klass() == NULL ? " and setting class object" : "") 364 ); 365 } 366 if (p->klass() == NULL) { 367 p->set_klass(klass); 368 } else { 369 assert(klass == NULL || p->klass() == klass, "constraints corrupted"); 370 } 371 } 372 373 374 void LoaderConstraintTable::merge_loader_constraints( 375 LoaderConstraintEntry** pp1, 376 LoaderConstraintEntry** pp2, 377 InstanceKlass* klass) { 378 // make sure *pp1 has higher capacity 379 if ((*pp1)->max_loaders() < (*pp2)->max_loaders()) { 380 LoaderConstraintEntry** tmp = pp2; 381 pp2 = pp1; 382 pp1 = tmp; 383 } 384 385 LoaderConstraintEntry* p1 = *pp1; 386 LoaderConstraintEntry* p2 = *pp2; 387 388 ensure_loader_constraint_capacity(p1, p2->num_loaders()); 389 390 for (int i = 0; i < p2->num_loaders(); i++) { 391 int num = p1->num_loaders(); 392 p1->set_loader_data(num, p2->loader_data(i)); 393 p1->set_num_loaders(num + 1); 394 } 395 396 if (log_is_enabled(Info, class, loader, constraints)) { 397 ResourceMark rm; 398 outputStream* out = Log(class, loader, constraints)::info_stream(); 399 out->print_cr("merged constraints for name %s, new loader list:", 400 p1->name()->as_C_string() 401 ); 402 403 for (int i = 0; i < p1->num_loaders(); i++) { 404 out->print_cr(" [%d]: %s", i, 405 p1->loader_data(i)->loader_name()); 406 } 407 if (p1->klass() == NULL) { 408 out->print_cr("... and setting class object"); 409 } 410 } 411 412 // p1->klass() will hold NULL if klass, p2->klass(), and old 413 // p1->klass() are all NULL. In addition, all three must have 414 // matching non-NULL values, otherwise either the constraints would 415 // have been violated, or the constraints had been corrupted (and an 416 // assertion would fail). 417 if (p2->klass() != NULL) { 418 assert(p2->klass() == klass, "constraints corrupted"); 419 } 420 if (p1->klass() == NULL) { 421 p1->set_klass(klass); 422 } else { 423 assert(p1->klass() == klass, "constraints corrupted"); 424 } 425 426 *pp2 = p2->next(); 427 FREE_C_HEAP_ARRAY(oop, p2->loaders()); 428 free_entry(p2); 429 return; 430 } 431 432 433 void LoaderConstraintTable::verify(PlaceholderTable* placeholders) { 434 Thread *thread = Thread::current(); 435 for (int cindex = 0; cindex < table_size(); cindex++) { 436 for (LoaderConstraintEntry* probe = bucket(cindex); 437 probe != NULL; 438 probe = probe->next()) { 439 if (probe->klass() != NULL) { 440 InstanceKlass* ik = probe->klass(); 441 guarantee(ik->name() == probe->name(), "name should match"); 442 Symbol* name = ik->name(); 443 ClassLoaderData* loader_data = ik->class_loader_data(); 444 Dictionary* dictionary = loader_data->dictionary_or_null(); 445 assert(dictionary != NULL, "no dictionary for this loader constraint entry?"); 446 unsigned int d_hash = dictionary->compute_hash(name); 447 int d_index = dictionary->hash_to_index(d_hash); 448 InstanceKlass* k = dictionary->find_class(d_index, d_hash, name); 449 if (k != NULL) { 450 // We found the class in the system dictionary, so we should 451 // make sure that the Klass* matches what we already have. 452 guarantee(k == probe->klass(), "klass should be in dictionary"); 453 } else { 454 // If we don't find the class in the system dictionary, it 455 // has to be in the placeholders table. 456 unsigned int p_hash = placeholders->compute_hash(name); 457 int p_index = placeholders->hash_to_index(p_hash); 458 PlaceholderEntry* entry = placeholders->get_entry(p_index, p_hash, 459 name, loader_data); 460 461 // The InstanceKlass might not be on the entry, so the only 462 // thing we can check here is whether we were successful in 463 // finding the class in the placeholders table. 464 guarantee(entry != NULL, "klass should be in the placeholders"); 465 } 466 } 467 for (int n = 0; n< probe->num_loaders(); n++) { 468 assert(ClassLoaderDataGraph::contains_loader_data(probe->loader_data(n)), "The loader is missing"); 469 } 470 } 471 } 472 } 473 474 #ifndef PRODUCT 475 476 // Called with the system dictionary lock held 477 void LoaderConstraintTable::print() { 478 ResourceMark rm; 479 assert_locked_or_safepoint(SystemDictionary_lock); 480 tty->print_cr("Java loader constraints (entries=%d, constraints=%d)", 481 table_size(), number_of_entries()); 482 for (int cindex = 0; cindex < table_size(); cindex++) { 483 for (LoaderConstraintEntry* probe = bucket(cindex); 484 probe != NULL; 485 probe = probe->next()) { 486 tty->print("%4d: ", cindex); 487 probe->name()->print(); 488 tty->print(" , loaders:"); 489 for (int n = 0; n < probe->num_loaders(); n++) { 490 probe->loader_data(n)->print_value(); 491 tty->print(", "); 492 } 493 tty->cr(); 494 } 495 } 496 } 497 #endif