1 /* 2 * Copyright (c) 2003, 2018, 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 "aot/aotLoader.hpp" 27 #include "classfile/classFileStream.hpp" 28 #include "classfile/metadataOnStackMark.hpp" 29 #include "classfile/systemDictionary.hpp" 30 #include "classfile/verifier.hpp" 31 #include "code/codeCache.hpp" 32 #include "compiler/compileBroker.hpp" 33 #include "interpreter/oopMapCache.hpp" 34 #include "interpreter/rewriter.hpp" 35 #include "logging/logStream.hpp" 36 #include "memory/metadataFactory.hpp" 37 #include "memory/metaspaceShared.hpp" 38 #include "memory/resourceArea.hpp" 39 #include "memory/universe.hpp" 40 #include "oops/fieldStreams.hpp" 41 #include "oops/klassVtable.hpp" 42 #include "oops/oop.inline.hpp" 43 #include "prims/jvmtiImpl.hpp" 44 #include "prims/jvmtiRedefineClasses.hpp" 45 #include "prims/jvmtiThreadState.inline.hpp" 46 #include "prims/resolvedMethodTable.hpp" 47 #include "prims/methodComparator.hpp" 48 #include "runtime/deoptimization.hpp" 49 #include "runtime/handles.inline.hpp" 50 #include "runtime/jniHandles.inline.hpp" 51 #include "runtime/relocator.hpp" 52 #include "runtime/safepointVerifiers.hpp" 53 #include "utilities/bitMap.inline.hpp" 54 #include "utilities/events.hpp" 55 56 Array<Method*>* VM_RedefineClasses::_old_methods = NULL; 57 Array<Method*>* VM_RedefineClasses::_new_methods = NULL; 58 Method** VM_RedefineClasses::_matching_old_methods = NULL; 59 Method** VM_RedefineClasses::_matching_new_methods = NULL; 60 Method** VM_RedefineClasses::_deleted_methods = NULL; 61 Method** VM_RedefineClasses::_added_methods = NULL; 62 int VM_RedefineClasses::_matching_methods_length = 0; 63 int VM_RedefineClasses::_deleted_methods_length = 0; 64 int VM_RedefineClasses::_added_methods_length = 0; 65 Klass* VM_RedefineClasses::_the_class = NULL; 66 67 68 VM_RedefineClasses::VM_RedefineClasses(jint class_count, 69 const jvmtiClassDefinition *class_defs, 70 JvmtiClassLoadKind class_load_kind) { 71 _class_count = class_count; 72 _class_defs = class_defs; 73 _class_load_kind = class_load_kind; 74 _any_class_has_resolved_methods = false; 75 _res = JVMTI_ERROR_NONE; 76 } 77 78 static inline InstanceKlass* get_ik(jclass def) { 79 oop mirror = JNIHandles::resolve_non_null(def); 80 return InstanceKlass::cast(java_lang_Class::as_Klass(mirror)); 81 } 82 83 // If any of the classes are being redefined, wait 84 // Parallel constant pool merging leads to indeterminate constant pools. 85 void VM_RedefineClasses::lock_classes() { 86 MutexLocker ml(RedefineClasses_lock); 87 bool has_redefined; 88 do { 89 has_redefined = false; 90 // Go through classes each time until none are being redefined. 91 for (int i = 0; i < _class_count; i++) { 92 if (get_ik(_class_defs[i].klass)->is_being_redefined()) { 93 RedefineClasses_lock->wait(); 94 has_redefined = true; 95 break; // for loop 96 } 97 } 98 } while (has_redefined); 99 for (int i = 0; i < _class_count; i++) { 100 get_ik(_class_defs[i].klass)->set_is_being_redefined(true); 101 } 102 RedefineClasses_lock->notify_all(); 103 } 104 105 void VM_RedefineClasses::unlock_classes() { 106 MutexLocker ml(RedefineClasses_lock); 107 for (int i = 0; i < _class_count; i++) { 108 assert(get_ik(_class_defs[i].klass)->is_being_redefined(), 109 "should be being redefined to get here"); 110 get_ik(_class_defs[i].klass)->set_is_being_redefined(false); 111 } 112 RedefineClasses_lock->notify_all(); 113 } 114 115 bool VM_RedefineClasses::doit_prologue() { 116 if (_class_count == 0) { 117 _res = JVMTI_ERROR_NONE; 118 return false; 119 } 120 if (_class_defs == NULL) { 121 _res = JVMTI_ERROR_NULL_POINTER; 122 return false; 123 } 124 for (int i = 0; i < _class_count; i++) { 125 if (_class_defs[i].klass == NULL) { 126 _res = JVMTI_ERROR_INVALID_CLASS; 127 return false; 128 } 129 if (_class_defs[i].class_byte_count == 0) { 130 _res = JVMTI_ERROR_INVALID_CLASS_FORMAT; 131 return false; 132 } 133 if (_class_defs[i].class_bytes == NULL) { 134 _res = JVMTI_ERROR_NULL_POINTER; 135 return false; 136 } 137 138 oop mirror = JNIHandles::resolve_non_null(_class_defs[i].klass); 139 // classes for primitives and arrays and vm anonymous classes cannot be redefined 140 // check here so following code can assume these classes are InstanceKlass 141 if (!is_modifiable_class(mirror)) { 142 _res = JVMTI_ERROR_UNMODIFIABLE_CLASS; 143 return false; 144 } 145 } 146 147 // Start timer after all the sanity checks; not quite accurate, but 148 // better than adding a bunch of stop() calls. 149 if (log_is_enabled(Info, redefine, class, timer)) { 150 _timer_vm_op_prologue.start(); 151 } 152 153 lock_classes(); 154 // We first load new class versions in the prologue, because somewhere down the 155 // call chain it is required that the current thread is a Java thread. 156 _res = load_new_class_versions(Thread::current()); 157 if (_res != JVMTI_ERROR_NONE) { 158 // free any successfully created classes, since none are redefined 159 for (int i = 0; i < _class_count; i++) { 160 if (_scratch_classes[i] != NULL) { 161 ClassLoaderData* cld = _scratch_classes[i]->class_loader_data(); 162 // Free the memory for this class at class unloading time. Not before 163 // because CMS might think this is still live. 164 InstanceKlass* ik = get_ik(_class_defs[i].klass); 165 if (ik->get_cached_class_file() == _scratch_classes[i]->get_cached_class_file()) { 166 // Don't double-free cached_class_file copied from the original class if error. 167 _scratch_classes[i]->set_cached_class_file(NULL); 168 } 169 cld->add_to_deallocate_list(InstanceKlass::cast(_scratch_classes[i])); 170 } 171 } 172 // Free os::malloc allocated memory in load_new_class_version. 173 os::free(_scratch_classes); 174 _timer_vm_op_prologue.stop(); 175 unlock_classes(); 176 return false; 177 } 178 179 _timer_vm_op_prologue.stop(); 180 return true; 181 } 182 183 void VM_RedefineClasses::doit() { 184 Thread *thread = Thread::current(); 185 186 #if INCLUDE_CDS 187 if (UseSharedSpaces) { 188 // Sharing is enabled so we remap the shared readonly space to 189 // shared readwrite, private just in case we need to redefine 190 // a shared class. We do the remap during the doit() phase of 191 // the safepoint to be safer. 192 if (!MetaspaceShared::remap_shared_readonly_as_readwrite()) { 193 log_info(redefine, class, load)("failed to remap shared readonly space to readwrite, private"); 194 _res = JVMTI_ERROR_INTERNAL; 195 return; 196 } 197 } 198 #endif 199 200 // Mark methods seen on stack and everywhere else so old methods are not 201 // cleaned up if they're on the stack. 202 MetadataOnStackMark md_on_stack(true); 203 HandleMark hm(thread); // make sure any handles created are deleted 204 // before the stack walk again. 205 206 for (int i = 0; i < _class_count; i++) { 207 redefine_single_class(_class_defs[i].klass, _scratch_classes[i], thread); 208 } 209 210 // Clean out MethodData pointing to old Method* 211 // Have to do this after all classes are redefined and all methods that 212 // are redefined are marked as old. 213 MethodDataCleaner clean_weak_method_links; 214 ClassLoaderDataGraph::classes_do(&clean_weak_method_links); 215 216 // JSR-292 support 217 if (_any_class_has_resolved_methods) { 218 bool trace_name_printed = false; 219 ResolvedMethodTable::adjust_method_entries(&trace_name_printed); 220 } 221 222 // Disable any dependent concurrent compilations 223 SystemDictionary::notice_modification(); 224 225 // Set flag indicating that some invariants are no longer true. 226 // See jvmtiExport.hpp for detailed explanation. 227 JvmtiExport::set_has_redefined_a_class(); 228 229 // check_class() is optionally called for product bits, but is 230 // always called for non-product bits. 231 #ifdef PRODUCT 232 if (log_is_enabled(Trace, redefine, class, obsolete, metadata)) { 233 #endif 234 log_trace(redefine, class, obsolete, metadata)("calling check_class"); 235 CheckClass check_class(thread); 236 ClassLoaderDataGraph::classes_do(&check_class); 237 #ifdef PRODUCT 238 } 239 #endif 240 } 241 242 void VM_RedefineClasses::doit_epilogue() { 243 unlock_classes(); 244 245 // Free os::malloc allocated memory. 246 os::free(_scratch_classes); 247 248 // Reset the_class to null for error printing. 249 _the_class = NULL; 250 251 if (log_is_enabled(Info, redefine, class, timer)) { 252 // Used to have separate timers for "doit" and "all", but the timer 253 // overhead skewed the measurements. 254 julong doit_time = _timer_rsc_phase1.milliseconds() + 255 _timer_rsc_phase2.milliseconds(); 256 julong all_time = _timer_vm_op_prologue.milliseconds() + doit_time; 257 258 log_info(redefine, class, timer) 259 ("vm_op: all=" JULONG_FORMAT " prologue=" JULONG_FORMAT " doit=" JULONG_FORMAT, 260 all_time, (julong)_timer_vm_op_prologue.milliseconds(), doit_time); 261 log_info(redefine, class, timer) 262 ("redefine_single_class: phase1=" JULONG_FORMAT " phase2=" JULONG_FORMAT, 263 (julong)_timer_rsc_phase1.milliseconds(), (julong)_timer_rsc_phase2.milliseconds()); 264 } 265 } 266 267 bool VM_RedefineClasses::is_modifiable_class(oop klass_mirror) { 268 // classes for primitives cannot be redefined 269 if (java_lang_Class::is_primitive(klass_mirror)) { 270 return false; 271 } 272 Klass* k = java_lang_Class::as_Klass(klass_mirror); 273 // classes for arrays cannot be redefined 274 if (k == NULL || !k->is_instance_klass()) { 275 return false; 276 } 277 278 // Cannot redefine or retransform an anonymous class. 279 if (InstanceKlass::cast(k)->is_anonymous()) { 280 return false; 281 } 282 return true; 283 } 284 285 // Append the current entry at scratch_i in scratch_cp to *merge_cp_p 286 // where the end of *merge_cp_p is specified by *merge_cp_length_p. For 287 // direct CP entries, there is just the current entry to append. For 288 // indirect and double-indirect CP entries, there are zero or more 289 // referenced CP entries along with the current entry to append. 290 // Indirect and double-indirect CP entries are handled by recursive 291 // calls to append_entry() as needed. The referenced CP entries are 292 // always appended to *merge_cp_p before the referee CP entry. These 293 // referenced CP entries may already exist in *merge_cp_p in which case 294 // there is nothing extra to append and only the current entry is 295 // appended. 296 void VM_RedefineClasses::append_entry(const constantPoolHandle& scratch_cp, 297 int scratch_i, constantPoolHandle *merge_cp_p, int *merge_cp_length_p, 298 TRAPS) { 299 300 // append is different depending on entry tag type 301 switch (scratch_cp->tag_at(scratch_i).value()) { 302 303 // The old verifier is implemented outside the VM. It loads classes, 304 // but does not resolve constant pool entries directly so we never 305 // see Class entries here with the old verifier. Similarly the old 306 // verifier does not like Class entries in the input constant pool. 307 // The split-verifier is implemented in the VM so it can optionally 308 // and directly resolve constant pool entries to load classes. The 309 // split-verifier can accept either Class entries or UnresolvedClass 310 // entries in the input constant pool. We revert the appended copy 311 // back to UnresolvedClass so that either verifier will be happy 312 // with the constant pool entry. 313 // 314 // this is an indirect CP entry so it needs special handling 315 case JVM_CONSTANT_Class: 316 case JVM_CONSTANT_UnresolvedClass: 317 { 318 int name_i = scratch_cp->klass_name_index_at(scratch_i); 319 int new_name_i = find_or_append_indirect_entry(scratch_cp, name_i, merge_cp_p, 320 merge_cp_length_p, THREAD); 321 322 if (new_name_i != name_i) { 323 log_trace(redefine, class, constantpool) 324 ("Class entry@%d name_index change: %d to %d", 325 *merge_cp_length_p, name_i, new_name_i); 326 } 327 328 (*merge_cp_p)->temp_unresolved_klass_at_put(*merge_cp_length_p, new_name_i); 329 if (scratch_i != *merge_cp_length_p) { 330 // The new entry in *merge_cp_p is at a different index than 331 // the new entry in scratch_cp so we need to map the index values. 332 map_index(scratch_cp, scratch_i, *merge_cp_length_p); 333 } 334 (*merge_cp_length_p)++; 335 } break; 336 337 // these are direct CP entries so they can be directly appended, 338 // but double and long take two constant pool entries 339 case JVM_CONSTANT_Double: // fall through 340 case JVM_CONSTANT_Long: 341 { 342 ConstantPool::copy_entry_to(scratch_cp, scratch_i, *merge_cp_p, *merge_cp_length_p, 343 THREAD); 344 345 if (scratch_i != *merge_cp_length_p) { 346 // The new entry in *merge_cp_p is at a different index than 347 // the new entry in scratch_cp so we need to map the index values. 348 map_index(scratch_cp, scratch_i, *merge_cp_length_p); 349 } 350 (*merge_cp_length_p) += 2; 351 } break; 352 353 // these are direct CP entries so they can be directly appended 354 case JVM_CONSTANT_Float: // fall through 355 case JVM_CONSTANT_Integer: // fall through 356 case JVM_CONSTANT_Utf8: // fall through 357 358 // This was an indirect CP entry, but it has been changed into 359 // Symbol*s so this entry can be directly appended. 360 case JVM_CONSTANT_String: // fall through 361 { 362 ConstantPool::copy_entry_to(scratch_cp, scratch_i, *merge_cp_p, *merge_cp_length_p, 363 THREAD); 364 365 if (scratch_i != *merge_cp_length_p) { 366 // The new entry in *merge_cp_p is at a different index than 367 // the new entry in scratch_cp so we need to map the index values. 368 map_index(scratch_cp, scratch_i, *merge_cp_length_p); 369 } 370 (*merge_cp_length_p)++; 371 } break; 372 373 // this is an indirect CP entry so it needs special handling 374 case JVM_CONSTANT_NameAndType: 375 { 376 int name_ref_i = scratch_cp->name_ref_index_at(scratch_i); 377 int new_name_ref_i = find_or_append_indirect_entry(scratch_cp, name_ref_i, merge_cp_p, 378 merge_cp_length_p, THREAD); 379 380 int signature_ref_i = scratch_cp->signature_ref_index_at(scratch_i); 381 int new_signature_ref_i = find_or_append_indirect_entry(scratch_cp, signature_ref_i, 382 merge_cp_p, merge_cp_length_p, 383 THREAD); 384 385 // If the referenced entries already exist in *merge_cp_p, then 386 // both new_name_ref_i and new_signature_ref_i will both be 0. 387 // In that case, all we are appending is the current entry. 388 if (new_name_ref_i != name_ref_i) { 389 log_trace(redefine, class, constantpool) 390 ("NameAndType entry@%d name_ref_index change: %d to %d", 391 *merge_cp_length_p, name_ref_i, new_name_ref_i); 392 } 393 if (new_signature_ref_i != signature_ref_i) { 394 log_trace(redefine, class, constantpool) 395 ("NameAndType entry@%d signature_ref_index change: %d to %d", 396 *merge_cp_length_p, signature_ref_i, new_signature_ref_i); 397 } 398 399 (*merge_cp_p)->name_and_type_at_put(*merge_cp_length_p, 400 new_name_ref_i, new_signature_ref_i); 401 if (scratch_i != *merge_cp_length_p) { 402 // The new entry in *merge_cp_p is at a different index than 403 // the new entry in scratch_cp so we need to map the index values. 404 map_index(scratch_cp, scratch_i, *merge_cp_length_p); 405 } 406 (*merge_cp_length_p)++; 407 } break; 408 409 // this is a double-indirect CP entry so it needs special handling 410 case JVM_CONSTANT_Fieldref: // fall through 411 case JVM_CONSTANT_InterfaceMethodref: // fall through 412 case JVM_CONSTANT_Methodref: 413 { 414 int klass_ref_i = scratch_cp->uncached_klass_ref_index_at(scratch_i); 415 int new_klass_ref_i = find_or_append_indirect_entry(scratch_cp, klass_ref_i, 416 merge_cp_p, merge_cp_length_p, THREAD); 417 418 int name_and_type_ref_i = scratch_cp->uncached_name_and_type_ref_index_at(scratch_i); 419 int new_name_and_type_ref_i = find_or_append_indirect_entry(scratch_cp, name_and_type_ref_i, 420 merge_cp_p, merge_cp_length_p, THREAD); 421 422 const char *entry_name = NULL; 423 switch (scratch_cp->tag_at(scratch_i).value()) { 424 case JVM_CONSTANT_Fieldref: 425 entry_name = "Fieldref"; 426 (*merge_cp_p)->field_at_put(*merge_cp_length_p, new_klass_ref_i, 427 new_name_and_type_ref_i); 428 break; 429 case JVM_CONSTANT_InterfaceMethodref: 430 entry_name = "IFMethodref"; 431 (*merge_cp_p)->interface_method_at_put(*merge_cp_length_p, 432 new_klass_ref_i, new_name_and_type_ref_i); 433 break; 434 case JVM_CONSTANT_Methodref: 435 entry_name = "Methodref"; 436 (*merge_cp_p)->method_at_put(*merge_cp_length_p, new_klass_ref_i, 437 new_name_and_type_ref_i); 438 break; 439 default: 440 guarantee(false, "bad switch"); 441 break; 442 } 443 444 if (klass_ref_i != new_klass_ref_i) { 445 log_trace(redefine, class, constantpool) 446 ("%s entry@%d class_index changed: %d to %d", entry_name, *merge_cp_length_p, klass_ref_i, new_klass_ref_i); 447 } 448 if (name_and_type_ref_i != new_name_and_type_ref_i) { 449 log_trace(redefine, class, constantpool) 450 ("%s entry@%d name_and_type_index changed: %d to %d", 451 entry_name, *merge_cp_length_p, name_and_type_ref_i, new_name_and_type_ref_i); 452 } 453 454 if (scratch_i != *merge_cp_length_p) { 455 // The new entry in *merge_cp_p is at a different index than 456 // the new entry in scratch_cp so we need to map the index values. 457 map_index(scratch_cp, scratch_i, *merge_cp_length_p); 458 } 459 (*merge_cp_length_p)++; 460 } break; 461 462 // this is an indirect CP entry so it needs special handling 463 case JVM_CONSTANT_MethodType: 464 { 465 int ref_i = scratch_cp->method_type_index_at(scratch_i); 466 int new_ref_i = find_or_append_indirect_entry(scratch_cp, ref_i, merge_cp_p, 467 merge_cp_length_p, THREAD); 468 if (new_ref_i != ref_i) { 469 log_trace(redefine, class, constantpool) 470 ("MethodType entry@%d ref_index change: %d to %d", *merge_cp_length_p, ref_i, new_ref_i); 471 } 472 (*merge_cp_p)->method_type_index_at_put(*merge_cp_length_p, new_ref_i); 473 if (scratch_i != *merge_cp_length_p) { 474 // The new entry in *merge_cp_p is at a different index than 475 // the new entry in scratch_cp so we need to map the index values. 476 map_index(scratch_cp, scratch_i, *merge_cp_length_p); 477 } 478 (*merge_cp_length_p)++; 479 } break; 480 481 // this is an indirect CP entry so it needs special handling 482 case JVM_CONSTANT_MethodHandle: 483 { 484 int ref_kind = scratch_cp->method_handle_ref_kind_at(scratch_i); 485 int ref_i = scratch_cp->method_handle_index_at(scratch_i); 486 int new_ref_i = find_or_append_indirect_entry(scratch_cp, ref_i, merge_cp_p, 487 merge_cp_length_p, THREAD); 488 if (new_ref_i != ref_i) { 489 log_trace(redefine, class, constantpool) 490 ("MethodHandle entry@%d ref_index change: %d to %d", *merge_cp_length_p, ref_i, new_ref_i); 491 } 492 (*merge_cp_p)->method_handle_index_at_put(*merge_cp_length_p, ref_kind, new_ref_i); 493 if (scratch_i != *merge_cp_length_p) { 494 // The new entry in *merge_cp_p is at a different index than 495 // the new entry in scratch_cp so we need to map the index values. 496 map_index(scratch_cp, scratch_i, *merge_cp_length_p); 497 } 498 (*merge_cp_length_p)++; 499 } break; 500 501 // this is an indirect CP entry so it needs special handling 502 case JVM_CONSTANT_Dynamic: // fall through 503 case JVM_CONSTANT_InvokeDynamic: 504 { 505 // Index of the bootstrap specifier in the operands array 506 int old_bs_i = scratch_cp->invoke_dynamic_bootstrap_specifier_index(scratch_i); 507 int new_bs_i = find_or_append_operand(scratch_cp, old_bs_i, merge_cp_p, 508 merge_cp_length_p, THREAD); 509 // The bootstrap method NameAndType_info index 510 int old_ref_i = scratch_cp->invoke_dynamic_name_and_type_ref_index_at(scratch_i); 511 int new_ref_i = find_or_append_indirect_entry(scratch_cp, old_ref_i, merge_cp_p, 512 merge_cp_length_p, THREAD); 513 if (new_bs_i != old_bs_i) { 514 log_trace(redefine, class, constantpool) 515 ("Dynamic entry@%d bootstrap_method_attr_index change: %d to %d", 516 *merge_cp_length_p, old_bs_i, new_bs_i); 517 } 518 if (new_ref_i != old_ref_i) { 519 log_trace(redefine, class, constantpool) 520 ("Dynamic entry@%d name_and_type_index change: %d to %d", *merge_cp_length_p, old_ref_i, new_ref_i); 521 } 522 523 if (scratch_cp->tag_at(scratch_i).is_dynamic_constant()) 524 (*merge_cp_p)->dynamic_constant_at_put(*merge_cp_length_p, new_bs_i, new_ref_i); 525 else 526 (*merge_cp_p)->invoke_dynamic_at_put(*merge_cp_length_p, new_bs_i, new_ref_i); 527 if (scratch_i != *merge_cp_length_p) { 528 // The new entry in *merge_cp_p is at a different index than 529 // the new entry in scratch_cp so we need to map the index values. 530 map_index(scratch_cp, scratch_i, *merge_cp_length_p); 531 } 532 (*merge_cp_length_p)++; 533 } break; 534 535 // At this stage, Class or UnresolvedClass could be in scratch_cp, but not 536 // ClassIndex 537 case JVM_CONSTANT_ClassIndex: // fall through 538 539 // Invalid is used as the tag for the second constant pool entry 540 // occupied by JVM_CONSTANT_Double or JVM_CONSTANT_Long. It should 541 // not be seen by itself. 542 case JVM_CONSTANT_Invalid: // fall through 543 544 // At this stage, String could be here, but not StringIndex 545 case JVM_CONSTANT_StringIndex: // fall through 546 547 // At this stage JVM_CONSTANT_UnresolvedClassInError should not be 548 // here 549 case JVM_CONSTANT_UnresolvedClassInError: // fall through 550 551 default: 552 { 553 // leave a breadcrumb 554 jbyte bad_value = scratch_cp->tag_at(scratch_i).value(); 555 ShouldNotReachHere(); 556 } break; 557 } // end switch tag value 558 } // end append_entry() 559 560 561 int VM_RedefineClasses::find_or_append_indirect_entry(const constantPoolHandle& scratch_cp, 562 int ref_i, constantPoolHandle *merge_cp_p, int *merge_cp_length_p, TRAPS) { 563 564 int new_ref_i = ref_i; 565 bool match = (ref_i < *merge_cp_length_p) && 566 scratch_cp->compare_entry_to(ref_i, *merge_cp_p, ref_i, THREAD); 567 568 if (!match) { 569 // forward reference in *merge_cp_p or not a direct match 570 int found_i = scratch_cp->find_matching_entry(ref_i, *merge_cp_p, THREAD); 571 if (found_i != 0) { 572 guarantee(found_i != ref_i, "compare_entry_to() and find_matching_entry() do not agree"); 573 // Found a matching entry somewhere else in *merge_cp_p so just need a mapping entry. 574 new_ref_i = found_i; 575 map_index(scratch_cp, ref_i, found_i); 576 } else { 577 // no match found so we have to append this entry to *merge_cp_p 578 append_entry(scratch_cp, ref_i, merge_cp_p, merge_cp_length_p, THREAD); 579 // The above call to append_entry() can only append one entry 580 // so the post call query of *merge_cp_length_p is only for 581 // the sake of consistency. 582 new_ref_i = *merge_cp_length_p - 1; 583 } 584 } 585 586 return new_ref_i; 587 } // end find_or_append_indirect_entry() 588 589 590 // Append a bootstrap specifier into the merge_cp operands that is semantically equal 591 // to the scratch_cp operands bootstrap specifier passed by the old_bs_i index. 592 // Recursively append new merge_cp entries referenced by the new bootstrap specifier. 593 void VM_RedefineClasses::append_operand(const constantPoolHandle& scratch_cp, int old_bs_i, 594 constantPoolHandle *merge_cp_p, int *merge_cp_length_p, TRAPS) { 595 596 int old_ref_i = scratch_cp->operand_bootstrap_method_ref_index_at(old_bs_i); 597 int new_ref_i = find_or_append_indirect_entry(scratch_cp, old_ref_i, merge_cp_p, 598 merge_cp_length_p, THREAD); 599 if (new_ref_i != old_ref_i) { 600 log_trace(redefine, class, constantpool) 601 ("operands entry@%d bootstrap method ref_index change: %d to %d", _operands_cur_length, old_ref_i, new_ref_i); 602 } 603 604 Array<u2>* merge_ops = (*merge_cp_p)->operands(); 605 int new_bs_i = _operands_cur_length; 606 // We have _operands_cur_length == 0 when the merge_cp operands is empty yet. 607 // However, the operand_offset_at(0) was set in the extend_operands() call. 608 int new_base = (new_bs_i == 0) ? (*merge_cp_p)->operand_offset_at(0) 609 : (*merge_cp_p)->operand_next_offset_at(new_bs_i - 1); 610 int argc = scratch_cp->operand_argument_count_at(old_bs_i); 611 612 ConstantPool::operand_offset_at_put(merge_ops, _operands_cur_length, new_base); 613 merge_ops->at_put(new_base++, new_ref_i); 614 merge_ops->at_put(new_base++, argc); 615 616 for (int i = 0; i < argc; i++) { 617 int old_arg_ref_i = scratch_cp->operand_argument_index_at(old_bs_i, i); 618 int new_arg_ref_i = find_or_append_indirect_entry(scratch_cp, old_arg_ref_i, merge_cp_p, 619 merge_cp_length_p, THREAD); 620 merge_ops->at_put(new_base++, new_arg_ref_i); 621 if (new_arg_ref_i != old_arg_ref_i) { 622 log_trace(redefine, class, constantpool) 623 ("operands entry@%d bootstrap method argument ref_index change: %d to %d", 624 _operands_cur_length, old_arg_ref_i, new_arg_ref_i); 625 } 626 } 627 if (old_bs_i != _operands_cur_length) { 628 // The bootstrap specifier in *merge_cp_p is at a different index than 629 // that in scratch_cp so we need to map the index values. 630 map_operand_index(old_bs_i, new_bs_i); 631 } 632 _operands_cur_length++; 633 } // end append_operand() 634 635 636 int VM_RedefineClasses::find_or_append_operand(const constantPoolHandle& scratch_cp, 637 int old_bs_i, constantPoolHandle *merge_cp_p, int *merge_cp_length_p, TRAPS) { 638 639 int new_bs_i = old_bs_i; // bootstrap specifier index 640 bool match = (old_bs_i < _operands_cur_length) && 641 scratch_cp->compare_operand_to(old_bs_i, *merge_cp_p, old_bs_i, THREAD); 642 643 if (!match) { 644 // forward reference in *merge_cp_p or not a direct match 645 int found_i = scratch_cp->find_matching_operand(old_bs_i, *merge_cp_p, 646 _operands_cur_length, THREAD); 647 if (found_i != -1) { 648 guarantee(found_i != old_bs_i, "compare_operand_to() and find_matching_operand() disagree"); 649 // found a matching operand somewhere else in *merge_cp_p so just need a mapping 650 new_bs_i = found_i; 651 map_operand_index(old_bs_i, found_i); 652 } else { 653 // no match found so we have to append this bootstrap specifier to *merge_cp_p 654 append_operand(scratch_cp, old_bs_i, merge_cp_p, merge_cp_length_p, THREAD); 655 new_bs_i = _operands_cur_length - 1; 656 } 657 } 658 return new_bs_i; 659 } // end find_or_append_operand() 660 661 662 void VM_RedefineClasses::finalize_operands_merge(const constantPoolHandle& merge_cp, TRAPS) { 663 if (merge_cp->operands() == NULL) { 664 return; 665 } 666 // Shrink the merge_cp operands 667 merge_cp->shrink_operands(_operands_cur_length, CHECK); 668 669 if (log_is_enabled(Trace, redefine, class, constantpool)) { 670 // don't want to loop unless we are tracing 671 int count = 0; 672 for (int i = 1; i < _operands_index_map_p->length(); i++) { 673 int value = _operands_index_map_p->at(i); 674 if (value != -1) { 675 log_trace(redefine, class, constantpool)("operands_index_map[%d]: old=%d new=%d", count, i, value); 676 count++; 677 } 678 } 679 } 680 // Clean-up 681 _operands_index_map_p = NULL; 682 _operands_cur_length = 0; 683 _operands_index_map_count = 0; 684 } // end finalize_operands_merge() 685 686 // Symbol* comparator for qsort 687 // The caller must have an active ResourceMark. 688 static int symcmp(const void* a, const void* b) { 689 char* astr = (*(Symbol**)a)->as_C_string(); 690 char* bstr = (*(Symbol**)b)->as_C_string(); 691 return strcmp(astr, bstr); 692 } 693 694 jvmtiError VM_RedefineClasses::compare_and_normalize_class_versions( 695 InstanceKlass* the_class, 696 InstanceKlass* scratch_class) { 697 int i; 698 699 // Check superclasses, or rather their names, since superclasses themselves can be 700 // requested to replace. 701 // Check for NULL superclass first since this might be java.lang.Object 702 if (the_class->super() != scratch_class->super() && 703 (the_class->super() == NULL || scratch_class->super() == NULL || 704 the_class->super()->name() != 705 scratch_class->super()->name())) { 706 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_HIERARCHY_CHANGED; 707 } 708 709 // Check if the number, names and order of directly implemented interfaces are the same. 710 // I think in principle we should just check if the sets of names of directly implemented 711 // interfaces are the same, i.e. the order of declaration (which, however, if changed in the 712 // .java file, also changes in .class file) should not matter. However, comparing sets is 713 // technically a bit more difficult, and, more importantly, I am not sure at present that the 714 // order of interfaces does not matter on the implementation level, i.e. that the VM does not 715 // rely on it somewhere. 716 Array<Klass*>* k_interfaces = the_class->local_interfaces(); 717 Array<Klass*>* k_new_interfaces = scratch_class->local_interfaces(); 718 int n_intfs = k_interfaces->length(); 719 if (n_intfs != k_new_interfaces->length()) { 720 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_HIERARCHY_CHANGED; 721 } 722 for (i = 0; i < n_intfs; i++) { 723 if (k_interfaces->at(i)->name() != 724 k_new_interfaces->at(i)->name()) { 725 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_HIERARCHY_CHANGED; 726 } 727 } 728 729 // Check whether class is in the error init state. 730 if (the_class->is_in_error_state()) { 731 // TBD #5057930: special error code is needed in 1.6 732 return JVMTI_ERROR_INVALID_CLASS; 733 } 734 735 // Check whether the class NestHost attribute has been changed. 736 { 737 Thread* thread = Thread::current(); 738 ResourceMark rm(thread); 739 JvmtiThreadState *state = JvmtiThreadState::state_for((JavaThread*)thread); 740 RedefineVerifyMark rvm(the_class, scratch_class, state); 741 u2 the_nest_host_idx = the_class->nest_host_index(); 742 u2 scr_nest_host_idx = scratch_class->nest_host_index(); 743 744 if (the_nest_host_idx != 0 && scr_nest_host_idx != 0) { 745 Symbol* the_sym = the_class->constants()->klass_name_at(the_nest_host_idx); 746 Symbol* scr_sym = scratch_class->constants()->klass_name_at(scr_nest_host_idx); 747 if (the_sym != scr_sym) { 748 log_trace(redefine, class, nestmates) 749 ("redefined class %s attribute change error: NestHost class: %s replaced with: %s", 750 the_class->external_name(), the_sym->as_C_string(), scr_sym->as_C_string()); 751 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_CLASS_ATTRIBUTE_CHANGED; 752 } 753 } else if ((the_nest_host_idx == 0) ^ (scr_nest_host_idx == 0)) { 754 const char* action_str = (the_nest_host_idx != 0) ? "removed" : "added"; 755 log_trace(redefine, class, nestmates) 756 ("redefined class %s attribute change error: NestHost attribute %s", 757 the_class->external_name(), action_str); 758 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_CLASS_ATTRIBUTE_CHANGED; 759 } 760 761 // Check whether the class NestMembers attribute has been changed. 762 Array<u2>* the_nest_members = the_class->nest_members(); 763 Array<u2>* scr_nest_members = scratch_class->nest_members(); 764 bool the_members_exists = the_nest_members != Universe::the_empty_short_array(); 765 bool scr_members_exists = scr_nest_members != Universe::the_empty_short_array(); 766 767 int members_len = the_nest_members->length(); 768 if (the_members_exists && scr_members_exists) { 769 if (members_len != scr_nest_members->length()) { 770 log_trace(redefine, class, nestmates) 771 ("redefined class %s attribute change error: NestMember len=%d changed to len=%d", 772 the_class->external_name(), members_len, scr_nest_members->length()); 773 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_CLASS_ATTRIBUTE_CHANGED; 774 } 775 776 // The order of entries in the NestMembers array is not specified so we 777 // have to explicitly check for the same contents. We do this by copying 778 // the referenced symbols into their own arrays, sorting them and then 779 // comparing each element pair. 780 781 Symbol** the_syms = NEW_RESOURCE_ARRAY_RETURN_NULL(Symbol*, members_len); 782 Symbol** scr_syms = NEW_RESOURCE_ARRAY_RETURN_NULL(Symbol*, members_len); 783 784 if (the_syms == NULL || scr_syms == NULL) { 785 return JVMTI_ERROR_OUT_OF_MEMORY; 786 } 787 788 for (int i = 0; i < members_len; i++) { 789 int the_cp_index = the_nest_members->at(i); 790 int scr_cp_index = scr_nest_members->at(i); 791 the_syms[i] = the_class->constants()->klass_name_at(the_cp_index); 792 scr_syms[i] = scratch_class->constants()->klass_name_at(scr_cp_index); 793 } 794 795 qsort(the_syms, members_len, sizeof(Symbol*), symcmp); 796 qsort(scr_syms, members_len, sizeof(Symbol*), symcmp); 797 798 for (int i = 0; i < members_len; i++) { 799 if (the_syms[i] != scr_syms[i]) { 800 log_trace(redefine, class, nestmates) 801 ("redefined class %s attribute change error: NestMembers[%d]: %s changed to %s", 802 the_class->external_name(), i, the_syms[i]->as_C_string(), scr_syms[i]->as_C_string()); 803 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_CLASS_ATTRIBUTE_CHANGED; 804 } 805 } 806 /* 807 for (int i = 0; i < members_len; i++) { 808 int the_cp_index = the_nest_members->at(i); 809 int scr_cp_index = scr_nest_members->at(i); 810 Symbol* the_sym = the_class->constants()->klass_name_at(the_cp_index); 811 Symbol* scr_sym = scratch_class->constants()->klass_name_at(scr_cp_index); 812 if (the_sym != scr_sym) { 813 log_trace(redefine, class, nestmates) 814 ("redefined class %s attribute change error: NestMembers[%d]: %s changed to %s", 815 the_class->external_name(), i, the_sym->as_C_string(), scr_sym->as_C_string()); 816 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_CLASS_ATTRIBUTE_CHANGED; 817 } 818 } 819 */ 820 } else if (the_members_exists ^ scr_members_exists) { 821 const char* action_str = (the_members_exists) ? "removed" : "added"; 822 log_trace(redefine, class, nestmates) 823 ("redefined class %s attribute change error: NestMembers attribute %s", 824 the_class->external_name(), action_str); 825 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_CLASS_ATTRIBUTE_CHANGED; 826 } 827 } 828 829 // Check whether class modifiers are the same. 830 jushort old_flags = (jushort) the_class->access_flags().get_flags(); 831 jushort new_flags = (jushort) scratch_class->access_flags().get_flags(); 832 if (old_flags != new_flags) { 833 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_CLASS_MODIFIERS_CHANGED; 834 } 835 836 // Check if the number, names, types and order of fields declared in these classes 837 // are the same. 838 JavaFieldStream old_fs(the_class); 839 JavaFieldStream new_fs(scratch_class); 840 for (; !old_fs.done() && !new_fs.done(); old_fs.next(), new_fs.next()) { 841 // access 842 old_flags = old_fs.access_flags().as_short(); 843 new_flags = new_fs.access_flags().as_short(); 844 if ((old_flags ^ new_flags) & JVM_RECOGNIZED_FIELD_MODIFIERS) { 845 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_SCHEMA_CHANGED; 846 } 847 // offset 848 if (old_fs.offset() != new_fs.offset()) { 849 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_SCHEMA_CHANGED; 850 } 851 // name and signature 852 Symbol* name_sym1 = the_class->constants()->symbol_at(old_fs.name_index()); 853 Symbol* sig_sym1 = the_class->constants()->symbol_at(old_fs.signature_index()); 854 Symbol* name_sym2 = scratch_class->constants()->symbol_at(new_fs.name_index()); 855 Symbol* sig_sym2 = scratch_class->constants()->symbol_at(new_fs.signature_index()); 856 if (name_sym1 != name_sym2 || sig_sym1 != sig_sym2) { 857 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_SCHEMA_CHANGED; 858 } 859 } 860 861 // If both streams aren't done then we have a differing number of 862 // fields. 863 if (!old_fs.done() || !new_fs.done()) { 864 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_SCHEMA_CHANGED; 865 } 866 867 // Do a parallel walk through the old and new methods. Detect 868 // cases where they match (exist in both), have been added in 869 // the new methods, or have been deleted (exist only in the 870 // old methods). The class file parser places methods in order 871 // by method name, but does not order overloaded methods by 872 // signature. In order to determine what fate befell the methods, 873 // this code places the overloaded new methods that have matching 874 // old methods in the same order as the old methods and places 875 // new overloaded methods at the end of overloaded methods of 876 // that name. The code for this order normalization is adapted 877 // from the algorithm used in InstanceKlass::find_method(). 878 // Since we are swapping out of order entries as we find them, 879 // we only have to search forward through the overloaded methods. 880 // Methods which are added and have the same name as an existing 881 // method (but different signature) will be put at the end of 882 // the methods with that name, and the name mismatch code will 883 // handle them. 884 Array<Method*>* k_old_methods(the_class->methods()); 885 Array<Method*>* k_new_methods(scratch_class->methods()); 886 int n_old_methods = k_old_methods->length(); 887 int n_new_methods = k_new_methods->length(); 888 Thread* thread = Thread::current(); 889 890 int ni = 0; 891 int oi = 0; 892 while (true) { 893 Method* k_old_method; 894 Method* k_new_method; 895 enum { matched, added, deleted, undetermined } method_was = undetermined; 896 897 if (oi >= n_old_methods) { 898 if (ni >= n_new_methods) { 899 break; // we've looked at everything, done 900 } 901 // New method at the end 902 k_new_method = k_new_methods->at(ni); 903 method_was = added; 904 } else if (ni >= n_new_methods) { 905 // Old method, at the end, is deleted 906 k_old_method = k_old_methods->at(oi); 907 method_was = deleted; 908 } else { 909 // There are more methods in both the old and new lists 910 k_old_method = k_old_methods->at(oi); 911 k_new_method = k_new_methods->at(ni); 912 if (k_old_method->name() != k_new_method->name()) { 913 // Methods are sorted by method name, so a mismatch means added 914 // or deleted 915 if (k_old_method->name()->fast_compare(k_new_method->name()) > 0) { 916 method_was = added; 917 } else { 918 method_was = deleted; 919 } 920 } else if (k_old_method->signature() == k_new_method->signature()) { 921 // Both the name and signature match 922 method_was = matched; 923 } else { 924 // The name matches, but the signature doesn't, which means we have to 925 // search forward through the new overloaded methods. 926 int nj; // outside the loop for post-loop check 927 for (nj = ni + 1; nj < n_new_methods; nj++) { 928 Method* m = k_new_methods->at(nj); 929 if (k_old_method->name() != m->name()) { 930 // reached another method name so no more overloaded methods 931 method_was = deleted; 932 break; 933 } 934 if (k_old_method->signature() == m->signature()) { 935 // found a match so swap the methods 936 k_new_methods->at_put(ni, m); 937 k_new_methods->at_put(nj, k_new_method); 938 k_new_method = m; 939 method_was = matched; 940 break; 941 } 942 } 943 944 if (nj >= n_new_methods) { 945 // reached the end without a match; so method was deleted 946 method_was = deleted; 947 } 948 } 949 } 950 951 switch (method_was) { 952 case matched: 953 // methods match, be sure modifiers do too 954 old_flags = (jushort) k_old_method->access_flags().get_flags(); 955 new_flags = (jushort) k_new_method->access_flags().get_flags(); 956 if ((old_flags ^ new_flags) & ~(JVM_ACC_NATIVE)) { 957 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_METHOD_MODIFIERS_CHANGED; 958 } 959 { 960 u2 new_num = k_new_method->method_idnum(); 961 u2 old_num = k_old_method->method_idnum(); 962 if (new_num != old_num) { 963 Method* idnum_owner = scratch_class->method_with_idnum(old_num); 964 if (idnum_owner != NULL) { 965 // There is already a method assigned this idnum -- switch them 966 // Take current and original idnum from the new_method 967 idnum_owner->set_method_idnum(new_num); 968 idnum_owner->set_orig_method_idnum(k_new_method->orig_method_idnum()); 969 } 970 // Take current and original idnum from the old_method 971 k_new_method->set_method_idnum(old_num); 972 k_new_method->set_orig_method_idnum(k_old_method->orig_method_idnum()); 973 if (thread->has_pending_exception()) { 974 return JVMTI_ERROR_OUT_OF_MEMORY; 975 } 976 } 977 } 978 log_trace(redefine, class, normalize) 979 ("Method matched: new: %s [%d] == old: %s [%d]", 980 k_new_method->name_and_sig_as_C_string(), ni, k_old_method->name_and_sig_as_C_string(), oi); 981 // advance to next pair of methods 982 ++oi; 983 ++ni; 984 break; 985 case added: 986 // method added, see if it is OK 987 new_flags = (jushort) k_new_method->access_flags().get_flags(); 988 if ((new_flags & JVM_ACC_PRIVATE) == 0 989 // hack: private should be treated as final, but alas 990 || (new_flags & (JVM_ACC_FINAL|JVM_ACC_STATIC)) == 0 991 ) { 992 // new methods must be private 993 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_METHOD_ADDED; 994 } 995 { 996 u2 num = the_class->next_method_idnum(); 997 if (num == ConstMethod::UNSET_IDNUM) { 998 // cannot add any more methods 999 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_METHOD_ADDED; 1000 } 1001 u2 new_num = k_new_method->method_idnum(); 1002 Method* idnum_owner = scratch_class->method_with_idnum(num); 1003 if (idnum_owner != NULL) { 1004 // There is already a method assigned this idnum -- switch them 1005 // Take current and original idnum from the new_method 1006 idnum_owner->set_method_idnum(new_num); 1007 idnum_owner->set_orig_method_idnum(k_new_method->orig_method_idnum()); 1008 } 1009 k_new_method->set_method_idnum(num); 1010 k_new_method->set_orig_method_idnum(num); 1011 if (thread->has_pending_exception()) { 1012 return JVMTI_ERROR_OUT_OF_MEMORY; 1013 } 1014 } 1015 log_trace(redefine, class, normalize) 1016 ("Method added: new: %s [%d]", k_new_method->name_and_sig_as_C_string(), ni); 1017 ++ni; // advance to next new method 1018 break; 1019 case deleted: 1020 // method deleted, see if it is OK 1021 old_flags = (jushort) k_old_method->access_flags().get_flags(); 1022 if ((old_flags & JVM_ACC_PRIVATE) == 0 1023 // hack: private should be treated as final, but alas 1024 || (old_flags & (JVM_ACC_FINAL|JVM_ACC_STATIC)) == 0 1025 ) { 1026 // deleted methods must be private 1027 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_METHOD_DELETED; 1028 } 1029 log_trace(redefine, class, normalize) 1030 ("Method deleted: old: %s [%d]", k_old_method->name_and_sig_as_C_string(), oi); 1031 ++oi; // advance to next old method 1032 break; 1033 default: 1034 ShouldNotReachHere(); 1035 } 1036 } 1037 1038 return JVMTI_ERROR_NONE; 1039 } 1040 1041 1042 // Find new constant pool index value for old constant pool index value 1043 // by seaching the index map. Returns zero (0) if there is no mapped 1044 // value for the old constant pool index. 1045 int VM_RedefineClasses::find_new_index(int old_index) { 1046 if (_index_map_count == 0) { 1047 // map is empty so nothing can be found 1048 return 0; 1049 } 1050 1051 if (old_index < 1 || old_index >= _index_map_p->length()) { 1052 // The old_index is out of range so it is not mapped. This should 1053 // not happen in regular constant pool merging use, but it can 1054 // happen if a corrupt annotation is processed. 1055 return 0; 1056 } 1057 1058 int value = _index_map_p->at(old_index); 1059 if (value == -1) { 1060 // the old_index is not mapped 1061 return 0; 1062 } 1063 1064 return value; 1065 } // end find_new_index() 1066 1067 1068 // Find new bootstrap specifier index value for old bootstrap specifier index 1069 // value by seaching the index map. Returns unused index (-1) if there is 1070 // no mapped value for the old bootstrap specifier index. 1071 int VM_RedefineClasses::find_new_operand_index(int old_index) { 1072 if (_operands_index_map_count == 0) { 1073 // map is empty so nothing can be found 1074 return -1; 1075 } 1076 1077 if (old_index == -1 || old_index >= _operands_index_map_p->length()) { 1078 // The old_index is out of range so it is not mapped. 1079 // This should not happen in regular constant pool merging use. 1080 return -1; 1081 } 1082 1083 int value = _operands_index_map_p->at(old_index); 1084 if (value == -1) { 1085 // the old_index is not mapped 1086 return -1; 1087 } 1088 1089 return value; 1090 } // end find_new_operand_index() 1091 1092 1093 // Returns true if the current mismatch is due to a resolved/unresolved 1094 // class pair. Otherwise, returns false. 1095 bool VM_RedefineClasses::is_unresolved_class_mismatch(const constantPoolHandle& cp1, 1096 int index1, const constantPoolHandle& cp2, int index2) { 1097 1098 jbyte t1 = cp1->tag_at(index1).value(); 1099 if (t1 != JVM_CONSTANT_Class && t1 != JVM_CONSTANT_UnresolvedClass) { 1100 return false; // wrong entry type; not our special case 1101 } 1102 1103 jbyte t2 = cp2->tag_at(index2).value(); 1104 if (t2 != JVM_CONSTANT_Class && t2 != JVM_CONSTANT_UnresolvedClass) { 1105 return false; // wrong entry type; not our special case 1106 } 1107 1108 if (t1 == t2) { 1109 return false; // not a mismatch; not our special case 1110 } 1111 1112 char *s1 = cp1->klass_name_at(index1)->as_C_string(); 1113 char *s2 = cp2->klass_name_at(index2)->as_C_string(); 1114 if (strcmp(s1, s2) != 0) { 1115 return false; // strings don't match; not our special case 1116 } 1117 1118 return true; // made it through the gauntlet; this is our special case 1119 } // end is_unresolved_class_mismatch() 1120 1121 1122 jvmtiError VM_RedefineClasses::load_new_class_versions(TRAPS) { 1123 1124 // For consistency allocate memory using os::malloc wrapper. 1125 _scratch_classes = (InstanceKlass**) 1126 os::malloc(sizeof(InstanceKlass*) * _class_count, mtClass); 1127 if (_scratch_classes == NULL) { 1128 return JVMTI_ERROR_OUT_OF_MEMORY; 1129 } 1130 // Zero initialize the _scratch_classes array. 1131 for (int i = 0; i < _class_count; i++) { 1132 _scratch_classes[i] = NULL; 1133 } 1134 1135 ResourceMark rm(THREAD); 1136 1137 JvmtiThreadState *state = JvmtiThreadState::state_for(JavaThread::current()); 1138 // state can only be NULL if the current thread is exiting which 1139 // should not happen since we're trying to do a RedefineClasses 1140 guarantee(state != NULL, "exiting thread calling load_new_class_versions"); 1141 for (int i = 0; i < _class_count; i++) { 1142 // Create HandleMark so that any handles created while loading new class 1143 // versions are deleted. Constant pools are deallocated while merging 1144 // constant pools 1145 HandleMark hm(THREAD); 1146 InstanceKlass* the_class = get_ik(_class_defs[i].klass); 1147 Symbol* the_class_sym = the_class->name(); 1148 1149 log_debug(redefine, class, load) 1150 ("loading name=%s kind=%d (avail_mem=" UINT64_FORMAT "K)", 1151 the_class->external_name(), _class_load_kind, os::available_memory() >> 10); 1152 1153 ClassFileStream st((u1*)_class_defs[i].class_bytes, 1154 _class_defs[i].class_byte_count, 1155 "__VM_RedefineClasses__", 1156 ClassFileStream::verify); 1157 1158 // Parse the stream. 1159 Handle the_class_loader(THREAD, the_class->class_loader()); 1160 Handle protection_domain(THREAD, the_class->protection_domain()); 1161 // Set redefined class handle in JvmtiThreadState class. 1162 // This redefined class is sent to agent event handler for class file 1163 // load hook event. 1164 state->set_class_being_redefined(the_class, _class_load_kind); 1165 1166 InstanceKlass* scratch_class = SystemDictionary::parse_stream( 1167 the_class_sym, 1168 the_class_loader, 1169 protection_domain, 1170 &st, 1171 THREAD); 1172 // Clear class_being_redefined just to be sure. 1173 state->clear_class_being_redefined(); 1174 1175 // TODO: if this is retransform, and nothing changed we can skip it 1176 1177 // Need to clean up allocated InstanceKlass if there's an error so assign 1178 // the result here. Caller deallocates all the scratch classes in case of 1179 // an error. 1180 _scratch_classes[i] = scratch_class; 1181 1182 if (HAS_PENDING_EXCEPTION) { 1183 Symbol* ex_name = PENDING_EXCEPTION->klass()->name(); 1184 log_info(redefine, class, load, exceptions)("parse_stream exception: '%s'", ex_name->as_C_string()); 1185 CLEAR_PENDING_EXCEPTION; 1186 1187 if (ex_name == vmSymbols::java_lang_UnsupportedClassVersionError()) { 1188 return JVMTI_ERROR_UNSUPPORTED_VERSION; 1189 } else if (ex_name == vmSymbols::java_lang_ClassFormatError()) { 1190 return JVMTI_ERROR_INVALID_CLASS_FORMAT; 1191 } else if (ex_name == vmSymbols::java_lang_ClassCircularityError()) { 1192 return JVMTI_ERROR_CIRCULAR_CLASS_DEFINITION; 1193 } else if (ex_name == vmSymbols::java_lang_NoClassDefFoundError()) { 1194 // The message will be "XXX (wrong name: YYY)" 1195 return JVMTI_ERROR_NAMES_DONT_MATCH; 1196 } else if (ex_name == vmSymbols::java_lang_OutOfMemoryError()) { 1197 return JVMTI_ERROR_OUT_OF_MEMORY; 1198 } else { // Just in case more exceptions can be thrown.. 1199 return JVMTI_ERROR_FAILS_VERIFICATION; 1200 } 1201 } 1202 1203 // Ensure class is linked before redefine 1204 if (!the_class->is_linked()) { 1205 the_class->link_class(THREAD); 1206 if (HAS_PENDING_EXCEPTION) { 1207 Symbol* ex_name = PENDING_EXCEPTION->klass()->name(); 1208 log_info(redefine, class, load, exceptions)("link_class exception: '%s'", ex_name->as_C_string()); 1209 CLEAR_PENDING_EXCEPTION; 1210 if (ex_name == vmSymbols::java_lang_OutOfMemoryError()) { 1211 return JVMTI_ERROR_OUT_OF_MEMORY; 1212 } else { 1213 return JVMTI_ERROR_INTERNAL; 1214 } 1215 } 1216 } 1217 1218 // Do the validity checks in compare_and_normalize_class_versions() 1219 // before verifying the byte codes. By doing these checks first, we 1220 // limit the number of functions that require redirection from 1221 // the_class to scratch_class. In particular, we don't have to 1222 // modify JNI GetSuperclass() and thus won't change its performance. 1223 jvmtiError res = compare_and_normalize_class_versions(the_class, 1224 scratch_class); 1225 if (res != JVMTI_ERROR_NONE) { 1226 return res; 1227 } 1228 1229 // verify what the caller passed us 1230 { 1231 // The bug 6214132 caused the verification to fail. 1232 // Information about the_class and scratch_class is temporarily 1233 // recorded into jvmtiThreadState. This data is used to redirect 1234 // the_class to scratch_class in the JVM_* functions called by the 1235 // verifier. Please, refer to jvmtiThreadState.hpp for the detailed 1236 // description. 1237 RedefineVerifyMark rvm(the_class, scratch_class, state); 1238 Verifier::verify( 1239 scratch_class, Verifier::ThrowException, true, THREAD); 1240 } 1241 1242 if (HAS_PENDING_EXCEPTION) { 1243 Symbol* ex_name = PENDING_EXCEPTION->klass()->name(); 1244 log_info(redefine, class, load, exceptions)("verify_byte_codes exception: '%s'", ex_name->as_C_string()); 1245 CLEAR_PENDING_EXCEPTION; 1246 if (ex_name == vmSymbols::java_lang_OutOfMemoryError()) { 1247 return JVMTI_ERROR_OUT_OF_MEMORY; 1248 } else { 1249 // tell the caller the bytecodes are bad 1250 return JVMTI_ERROR_FAILS_VERIFICATION; 1251 } 1252 } 1253 1254 res = merge_cp_and_rewrite(the_class, scratch_class, THREAD); 1255 if (HAS_PENDING_EXCEPTION) { 1256 Symbol* ex_name = PENDING_EXCEPTION->klass()->name(); 1257 log_info(redefine, class, load, exceptions)("merge_cp_and_rewrite exception: '%s'", ex_name->as_C_string()); 1258 CLEAR_PENDING_EXCEPTION; 1259 if (ex_name == vmSymbols::java_lang_OutOfMemoryError()) { 1260 return JVMTI_ERROR_OUT_OF_MEMORY; 1261 } else { 1262 return JVMTI_ERROR_INTERNAL; 1263 } 1264 } 1265 1266 if (VerifyMergedCPBytecodes) { 1267 // verify what we have done during constant pool merging 1268 { 1269 RedefineVerifyMark rvm(the_class, scratch_class, state); 1270 Verifier::verify(scratch_class, Verifier::ThrowException, true, THREAD); 1271 } 1272 1273 if (HAS_PENDING_EXCEPTION) { 1274 Symbol* ex_name = PENDING_EXCEPTION->klass()->name(); 1275 log_info(redefine, class, load, exceptions) 1276 ("verify_byte_codes post merge-CP exception: '%s'", ex_name->as_C_string()); 1277 CLEAR_PENDING_EXCEPTION; 1278 if (ex_name == vmSymbols::java_lang_OutOfMemoryError()) { 1279 return JVMTI_ERROR_OUT_OF_MEMORY; 1280 } else { 1281 // tell the caller that constant pool merging screwed up 1282 return JVMTI_ERROR_INTERNAL; 1283 } 1284 } 1285 } 1286 1287 Rewriter::rewrite(scratch_class, THREAD); 1288 if (!HAS_PENDING_EXCEPTION) { 1289 scratch_class->link_methods(THREAD); 1290 } 1291 if (HAS_PENDING_EXCEPTION) { 1292 Symbol* ex_name = PENDING_EXCEPTION->klass()->name(); 1293 log_info(redefine, class, load, exceptions) 1294 ("Rewriter::rewrite or link_methods exception: '%s'", ex_name->as_C_string()); 1295 CLEAR_PENDING_EXCEPTION; 1296 if (ex_name == vmSymbols::java_lang_OutOfMemoryError()) { 1297 return JVMTI_ERROR_OUT_OF_MEMORY; 1298 } else { 1299 return JVMTI_ERROR_INTERNAL; 1300 } 1301 } 1302 1303 log_debug(redefine, class, load) 1304 ("loaded name=%s (avail_mem=" UINT64_FORMAT "K)", the_class->external_name(), os::available_memory() >> 10); 1305 } 1306 1307 return JVMTI_ERROR_NONE; 1308 } 1309 1310 1311 // Map old_index to new_index as needed. scratch_cp is only needed 1312 // for log calls. 1313 void VM_RedefineClasses::map_index(const constantPoolHandle& scratch_cp, 1314 int old_index, int new_index) { 1315 if (find_new_index(old_index) != 0) { 1316 // old_index is already mapped 1317 return; 1318 } 1319 1320 if (old_index == new_index) { 1321 // no mapping is needed 1322 return; 1323 } 1324 1325 _index_map_p->at_put(old_index, new_index); 1326 _index_map_count++; 1327 1328 log_trace(redefine, class, constantpool) 1329 ("mapped tag %d at index %d to %d", scratch_cp->tag_at(old_index).value(), old_index, new_index); 1330 } // end map_index() 1331 1332 1333 // Map old_index to new_index as needed. 1334 void VM_RedefineClasses::map_operand_index(int old_index, int new_index) { 1335 if (find_new_operand_index(old_index) != -1) { 1336 // old_index is already mapped 1337 return; 1338 } 1339 1340 if (old_index == new_index) { 1341 // no mapping is needed 1342 return; 1343 } 1344 1345 _operands_index_map_p->at_put(old_index, new_index); 1346 _operands_index_map_count++; 1347 1348 log_trace(redefine, class, constantpool)("mapped bootstrap specifier at index %d to %d", old_index, new_index); 1349 } // end map_index() 1350 1351 1352 // Merge old_cp and scratch_cp and return the results of the merge via 1353 // merge_cp_p. The number of entries in *merge_cp_p is returned via 1354 // merge_cp_length_p. The entries in old_cp occupy the same locations 1355 // in *merge_cp_p. Also creates a map of indices from entries in 1356 // scratch_cp to the corresponding entry in *merge_cp_p. Index map 1357 // entries are only created for entries in scratch_cp that occupy a 1358 // different location in *merged_cp_p. 1359 bool VM_RedefineClasses::merge_constant_pools(const constantPoolHandle& old_cp, 1360 const constantPoolHandle& scratch_cp, constantPoolHandle *merge_cp_p, 1361 int *merge_cp_length_p, TRAPS) { 1362 1363 if (merge_cp_p == NULL) { 1364 assert(false, "caller must provide scratch constantPool"); 1365 return false; // robustness 1366 } 1367 if (merge_cp_length_p == NULL) { 1368 assert(false, "caller must provide scratch CP length"); 1369 return false; // robustness 1370 } 1371 // Worst case we need old_cp->length() + scratch_cp()->length(), 1372 // but the caller might be smart so make sure we have at least 1373 // the minimum. 1374 if ((*merge_cp_p)->length() < old_cp->length()) { 1375 assert(false, "merge area too small"); 1376 return false; // robustness 1377 } 1378 1379 log_info(redefine, class, constantpool)("old_cp_len=%d, scratch_cp_len=%d", old_cp->length(), scratch_cp->length()); 1380 1381 { 1382 // Pass 0: 1383 // The old_cp is copied to *merge_cp_p; this means that any code 1384 // using old_cp does not have to change. This work looks like a 1385 // perfect fit for ConstantPool*::copy_cp_to(), but we need to 1386 // handle one special case: 1387 // - revert JVM_CONSTANT_Class to JVM_CONSTANT_UnresolvedClass 1388 // This will make verification happy. 1389 1390 int old_i; // index into old_cp 1391 1392 // index zero (0) is not used in constantPools 1393 for (old_i = 1; old_i < old_cp->length(); old_i++) { 1394 // leave debugging crumb 1395 jbyte old_tag = old_cp->tag_at(old_i).value(); 1396 switch (old_tag) { 1397 case JVM_CONSTANT_Class: 1398 case JVM_CONSTANT_UnresolvedClass: 1399 // revert the copy to JVM_CONSTANT_UnresolvedClass 1400 // May be resolving while calling this so do the same for 1401 // JVM_CONSTANT_UnresolvedClass (klass_name_at() deals with transition) 1402 (*merge_cp_p)->temp_unresolved_klass_at_put(old_i, 1403 old_cp->klass_name_index_at(old_i)); 1404 break; 1405 1406 case JVM_CONSTANT_Double: 1407 case JVM_CONSTANT_Long: 1408 // just copy the entry to *merge_cp_p, but double and long take 1409 // two constant pool entries 1410 ConstantPool::copy_entry_to(old_cp, old_i, *merge_cp_p, old_i, CHECK_0); 1411 old_i++; 1412 break; 1413 1414 default: 1415 // just copy the entry to *merge_cp_p 1416 ConstantPool::copy_entry_to(old_cp, old_i, *merge_cp_p, old_i, CHECK_0); 1417 break; 1418 } 1419 } // end for each old_cp entry 1420 1421 ConstantPool::copy_operands(old_cp, *merge_cp_p, CHECK_0); 1422 (*merge_cp_p)->extend_operands(scratch_cp, CHECK_0); 1423 1424 // We don't need to sanity check that *merge_cp_length_p is within 1425 // *merge_cp_p bounds since we have the minimum on-entry check above. 1426 (*merge_cp_length_p) = old_i; 1427 } 1428 1429 // merge_cp_len should be the same as old_cp->length() at this point 1430 // so this trace message is really a "warm-and-breathing" message. 1431 log_debug(redefine, class, constantpool)("after pass 0: merge_cp_len=%d", *merge_cp_length_p); 1432 1433 int scratch_i; // index into scratch_cp 1434 { 1435 // Pass 1a: 1436 // Compare scratch_cp entries to the old_cp entries that we have 1437 // already copied to *merge_cp_p. In this pass, we are eliminating 1438 // exact duplicates (matching entry at same index) so we only 1439 // compare entries in the common indice range. 1440 int increment = 1; 1441 int pass1a_length = MIN2(old_cp->length(), scratch_cp->length()); 1442 for (scratch_i = 1; scratch_i < pass1a_length; scratch_i += increment) { 1443 switch (scratch_cp->tag_at(scratch_i).value()) { 1444 case JVM_CONSTANT_Double: 1445 case JVM_CONSTANT_Long: 1446 // double and long take two constant pool entries 1447 increment = 2; 1448 break; 1449 1450 default: 1451 increment = 1; 1452 break; 1453 } 1454 1455 bool match = scratch_cp->compare_entry_to(scratch_i, *merge_cp_p, 1456 scratch_i, CHECK_0); 1457 if (match) { 1458 // found a match at the same index so nothing more to do 1459 continue; 1460 } else if (is_unresolved_class_mismatch(scratch_cp, scratch_i, 1461 *merge_cp_p, scratch_i)) { 1462 // The mismatch in compare_entry_to() above is because of a 1463 // resolved versus unresolved class entry at the same index 1464 // with the same string value. Since Pass 0 reverted any 1465 // class entries to unresolved class entries in *merge_cp_p, 1466 // we go with the unresolved class entry. 1467 continue; 1468 } 1469 1470 int found_i = scratch_cp->find_matching_entry(scratch_i, *merge_cp_p, 1471 CHECK_0); 1472 if (found_i != 0) { 1473 guarantee(found_i != scratch_i, 1474 "compare_entry_to() and find_matching_entry() do not agree"); 1475 1476 // Found a matching entry somewhere else in *merge_cp_p so 1477 // just need a mapping entry. 1478 map_index(scratch_cp, scratch_i, found_i); 1479 continue; 1480 } 1481 1482 // The find_matching_entry() call above could fail to find a match 1483 // due to a resolved versus unresolved class or string entry situation 1484 // like we solved above with the is_unresolved_*_mismatch() calls. 1485 // However, we would have to call is_unresolved_*_mismatch() over 1486 // all of *merge_cp_p (potentially) and that doesn't seem to be 1487 // worth the time. 1488 1489 // No match found so we have to append this entry and any unique 1490 // referenced entries to *merge_cp_p. 1491 append_entry(scratch_cp, scratch_i, merge_cp_p, merge_cp_length_p, 1492 CHECK_0); 1493 } 1494 } 1495 1496 log_debug(redefine, class, constantpool) 1497 ("after pass 1a: merge_cp_len=%d, scratch_i=%d, index_map_len=%d", 1498 *merge_cp_length_p, scratch_i, _index_map_count); 1499 1500 if (scratch_i < scratch_cp->length()) { 1501 // Pass 1b: 1502 // old_cp is smaller than scratch_cp so there are entries in 1503 // scratch_cp that we have not yet processed. We take care of 1504 // those now. 1505 int increment = 1; 1506 for (; scratch_i < scratch_cp->length(); scratch_i += increment) { 1507 switch (scratch_cp->tag_at(scratch_i).value()) { 1508 case JVM_CONSTANT_Double: 1509 case JVM_CONSTANT_Long: 1510 // double and long take two constant pool entries 1511 increment = 2; 1512 break; 1513 1514 default: 1515 increment = 1; 1516 break; 1517 } 1518 1519 int found_i = 1520 scratch_cp->find_matching_entry(scratch_i, *merge_cp_p, CHECK_0); 1521 if (found_i != 0) { 1522 // Found a matching entry somewhere else in *merge_cp_p so 1523 // just need a mapping entry. 1524 map_index(scratch_cp, scratch_i, found_i); 1525 continue; 1526 } 1527 1528 // No match found so we have to append this entry and any unique 1529 // referenced entries to *merge_cp_p. 1530 append_entry(scratch_cp, scratch_i, merge_cp_p, merge_cp_length_p, 1531 CHECK_0); 1532 } 1533 1534 log_debug(redefine, class, constantpool) 1535 ("after pass 1b: merge_cp_len=%d, scratch_i=%d, index_map_len=%d", 1536 *merge_cp_length_p, scratch_i, _index_map_count); 1537 } 1538 finalize_operands_merge(*merge_cp_p, THREAD); 1539 1540 return true; 1541 } // end merge_constant_pools() 1542 1543 1544 // Scoped object to clean up the constant pool(s) created for merging 1545 class MergeCPCleaner { 1546 ClassLoaderData* _loader_data; 1547 ConstantPool* _cp; 1548 ConstantPool* _scratch_cp; 1549 public: 1550 MergeCPCleaner(ClassLoaderData* loader_data, ConstantPool* merge_cp) : 1551 _loader_data(loader_data), _cp(merge_cp), _scratch_cp(NULL) {} 1552 ~MergeCPCleaner() { 1553 _loader_data->add_to_deallocate_list(_cp); 1554 if (_scratch_cp != NULL) { 1555 _loader_data->add_to_deallocate_list(_scratch_cp); 1556 } 1557 } 1558 void add_scratch_cp(ConstantPool* scratch_cp) { _scratch_cp = scratch_cp; } 1559 }; 1560 1561 // Merge constant pools between the_class and scratch_class and 1562 // potentially rewrite bytecodes in scratch_class to use the merged 1563 // constant pool. 1564 jvmtiError VM_RedefineClasses::merge_cp_and_rewrite( 1565 InstanceKlass* the_class, InstanceKlass* scratch_class, 1566 TRAPS) { 1567 // worst case merged constant pool length is old and new combined 1568 int merge_cp_length = the_class->constants()->length() 1569 + scratch_class->constants()->length(); 1570 1571 // Constant pools are not easily reused so we allocate a new one 1572 // each time. 1573 // merge_cp is created unsafe for concurrent GC processing. It 1574 // should be marked safe before discarding it. Even though 1575 // garbage, if it crosses a card boundary, it may be scanned 1576 // in order to find the start of the first complete object on the card. 1577 ClassLoaderData* loader_data = the_class->class_loader_data(); 1578 ConstantPool* merge_cp_oop = 1579 ConstantPool::allocate(loader_data, 1580 merge_cp_length, 1581 CHECK_(JVMTI_ERROR_OUT_OF_MEMORY)); 1582 MergeCPCleaner cp_cleaner(loader_data, merge_cp_oop); 1583 1584 HandleMark hm(THREAD); // make sure handles are cleared before 1585 // MergeCPCleaner clears out merge_cp_oop 1586 constantPoolHandle merge_cp(THREAD, merge_cp_oop); 1587 1588 // Get constants() from the old class because it could have been rewritten 1589 // while we were at a safepoint allocating a new constant pool. 1590 constantPoolHandle old_cp(THREAD, the_class->constants()); 1591 constantPoolHandle scratch_cp(THREAD, scratch_class->constants()); 1592 1593 // If the length changed, the class was redefined out from under us. Return 1594 // an error. 1595 if (merge_cp_length != the_class->constants()->length() 1596 + scratch_class->constants()->length()) { 1597 return JVMTI_ERROR_INTERNAL; 1598 } 1599 1600 // Update the version number of the constant pools (may keep scratch_cp) 1601 merge_cp->increment_and_save_version(old_cp->version()); 1602 scratch_cp->increment_and_save_version(old_cp->version()); 1603 1604 ResourceMark rm(THREAD); 1605 _index_map_count = 0; 1606 _index_map_p = new intArray(scratch_cp->length(), scratch_cp->length(), -1); 1607 1608 _operands_cur_length = ConstantPool::operand_array_length(old_cp->operands()); 1609 _operands_index_map_count = 0; 1610 int operands_index_map_len = ConstantPool::operand_array_length(scratch_cp->operands()); 1611 _operands_index_map_p = new intArray(operands_index_map_len, operands_index_map_len, -1); 1612 1613 // reference to the cp holder is needed for copy_operands() 1614 merge_cp->set_pool_holder(scratch_class); 1615 bool result = merge_constant_pools(old_cp, scratch_cp, &merge_cp, 1616 &merge_cp_length, THREAD); 1617 merge_cp->set_pool_holder(NULL); 1618 1619 if (!result) { 1620 // The merge can fail due to memory allocation failure or due 1621 // to robustness checks. 1622 return JVMTI_ERROR_INTERNAL; 1623 } 1624 1625 log_info(redefine, class, constantpool)("merge_cp_len=%d, index_map_len=%d", merge_cp_length, _index_map_count); 1626 1627 if (_index_map_count == 0) { 1628 // there is nothing to map between the new and merged constant pools 1629 1630 if (old_cp->length() == scratch_cp->length()) { 1631 // The old and new constant pools are the same length and the 1632 // index map is empty. This means that the three constant pools 1633 // are equivalent (but not the same). Unfortunately, the new 1634 // constant pool has not gone through link resolution nor have 1635 // the new class bytecodes gone through constant pool cache 1636 // rewriting so we can't use the old constant pool with the new 1637 // class. 1638 1639 // toss the merged constant pool at return 1640 } else if (old_cp->length() < scratch_cp->length()) { 1641 // The old constant pool has fewer entries than the new constant 1642 // pool and the index map is empty. This means the new constant 1643 // pool is a superset of the old constant pool. However, the old 1644 // class bytecodes have already gone through constant pool cache 1645 // rewriting so we can't use the new constant pool with the old 1646 // class. 1647 1648 // toss the merged constant pool at return 1649 } else { 1650 // The old constant pool has more entries than the new constant 1651 // pool and the index map is empty. This means that both the old 1652 // and merged constant pools are supersets of the new constant 1653 // pool. 1654 1655 // Replace the new constant pool with a shrunken copy of the 1656 // merged constant pool 1657 set_new_constant_pool(loader_data, scratch_class, merge_cp, merge_cp_length, 1658 CHECK_(JVMTI_ERROR_OUT_OF_MEMORY)); 1659 // The new constant pool replaces scratch_cp so have cleaner clean it up. 1660 // It can't be cleaned up while there are handles to it. 1661 cp_cleaner.add_scratch_cp(scratch_cp()); 1662 } 1663 } else { 1664 if (log_is_enabled(Trace, redefine, class, constantpool)) { 1665 // don't want to loop unless we are tracing 1666 int count = 0; 1667 for (int i = 1; i < _index_map_p->length(); i++) { 1668 int value = _index_map_p->at(i); 1669 1670 if (value != -1) { 1671 log_trace(redefine, class, constantpool)("index_map[%d]: old=%d new=%d", count, i, value); 1672 count++; 1673 } 1674 } 1675 } 1676 1677 // We have entries mapped between the new and merged constant pools 1678 // so we have to rewrite some constant pool references. 1679 if (!rewrite_cp_refs(scratch_class, THREAD)) { 1680 return JVMTI_ERROR_INTERNAL; 1681 } 1682 1683 // Replace the new constant pool with a shrunken copy of the 1684 // merged constant pool so now the rewritten bytecodes have 1685 // valid references; the previous new constant pool will get 1686 // GCed. 1687 set_new_constant_pool(loader_data, scratch_class, merge_cp, merge_cp_length, 1688 CHECK_(JVMTI_ERROR_OUT_OF_MEMORY)); 1689 // The new constant pool replaces scratch_cp so have cleaner clean it up. 1690 // It can't be cleaned up while there are handles to it. 1691 cp_cleaner.add_scratch_cp(scratch_cp()); 1692 } 1693 1694 return JVMTI_ERROR_NONE; 1695 } // end merge_cp_and_rewrite() 1696 1697 1698 // Rewrite constant pool references in klass scratch_class. 1699 bool VM_RedefineClasses::rewrite_cp_refs(InstanceKlass* scratch_class, 1700 TRAPS) { 1701 1702 // rewrite constant pool references in the nest attributes: 1703 if (!rewrite_cp_refs_in_nest_attributes(scratch_class)) { 1704 // propagate failure back to caller 1705 return false; 1706 } 1707 1708 // rewrite constant pool references in the methods: 1709 if (!rewrite_cp_refs_in_methods(scratch_class, THREAD)) { 1710 // propagate failure back to caller 1711 return false; 1712 } 1713 1714 // rewrite constant pool references in the class_annotations: 1715 if (!rewrite_cp_refs_in_class_annotations(scratch_class, THREAD)) { 1716 // propagate failure back to caller 1717 return false; 1718 } 1719 1720 // rewrite constant pool references in the fields_annotations: 1721 if (!rewrite_cp_refs_in_fields_annotations(scratch_class, THREAD)) { 1722 // propagate failure back to caller 1723 return false; 1724 } 1725 1726 // rewrite constant pool references in the methods_annotations: 1727 if (!rewrite_cp_refs_in_methods_annotations(scratch_class, THREAD)) { 1728 // propagate failure back to caller 1729 return false; 1730 } 1731 1732 // rewrite constant pool references in the methods_parameter_annotations: 1733 if (!rewrite_cp_refs_in_methods_parameter_annotations(scratch_class, 1734 THREAD)) { 1735 // propagate failure back to caller 1736 return false; 1737 } 1738 1739 // rewrite constant pool references in the methods_default_annotations: 1740 if (!rewrite_cp_refs_in_methods_default_annotations(scratch_class, 1741 THREAD)) { 1742 // propagate failure back to caller 1743 return false; 1744 } 1745 1746 // rewrite constant pool references in the class_type_annotations: 1747 if (!rewrite_cp_refs_in_class_type_annotations(scratch_class, THREAD)) { 1748 // propagate failure back to caller 1749 return false; 1750 } 1751 1752 // rewrite constant pool references in the fields_type_annotations: 1753 if (!rewrite_cp_refs_in_fields_type_annotations(scratch_class, THREAD)) { 1754 // propagate failure back to caller 1755 return false; 1756 } 1757 1758 // rewrite constant pool references in the methods_type_annotations: 1759 if (!rewrite_cp_refs_in_methods_type_annotations(scratch_class, THREAD)) { 1760 // propagate failure back to caller 1761 return false; 1762 } 1763 1764 // There can be type annotations in the Code part of a method_info attribute. 1765 // These annotations are not accessible, even by reflection. 1766 // Currently they are not even parsed by the ClassFileParser. 1767 // If runtime access is added they will also need to be rewritten. 1768 1769 // rewrite source file name index: 1770 u2 source_file_name_idx = scratch_class->source_file_name_index(); 1771 if (source_file_name_idx != 0) { 1772 u2 new_source_file_name_idx = find_new_index(source_file_name_idx); 1773 if (new_source_file_name_idx != 0) { 1774 scratch_class->set_source_file_name_index(new_source_file_name_idx); 1775 } 1776 } 1777 1778 // rewrite class generic signature index: 1779 u2 generic_signature_index = scratch_class->generic_signature_index(); 1780 if (generic_signature_index != 0) { 1781 u2 new_generic_signature_index = find_new_index(generic_signature_index); 1782 if (new_generic_signature_index != 0) { 1783 scratch_class->set_generic_signature_index(new_generic_signature_index); 1784 } 1785 } 1786 1787 return true; 1788 } // end rewrite_cp_refs() 1789 1790 // Rewrite constant pool references in the NestHost and NestMembers attributes. 1791 bool VM_RedefineClasses::rewrite_cp_refs_in_nest_attributes( 1792 InstanceKlass* scratch_class) { 1793 1794 u2 cp_index = scratch_class->nest_host_index(); 1795 if (cp_index != 0) { 1796 scratch_class->set_nest_host_index(find_new_index(cp_index)); 1797 } 1798 Array<u2>* nest_members = scratch_class->nest_members(); 1799 for (int i = 0; i < nest_members->length(); i++) { 1800 u2 cp_index = nest_members->at(i); 1801 nest_members->at_put(i, find_new_index(cp_index)); 1802 } 1803 return true; 1804 } 1805 1806 // Rewrite constant pool references in the methods. 1807 bool VM_RedefineClasses::rewrite_cp_refs_in_methods( 1808 InstanceKlass* scratch_class, TRAPS) { 1809 1810 Array<Method*>* methods = scratch_class->methods(); 1811 1812 if (methods == NULL || methods->length() == 0) { 1813 // no methods so nothing to do 1814 return true; 1815 } 1816 1817 // rewrite constant pool references in the methods: 1818 for (int i = methods->length() - 1; i >= 0; i--) { 1819 methodHandle method(THREAD, methods->at(i)); 1820 methodHandle new_method; 1821 rewrite_cp_refs_in_method(method, &new_method, THREAD); 1822 if (!new_method.is_null()) { 1823 // the method has been replaced so save the new method version 1824 // even in the case of an exception. original method is on the 1825 // deallocation list. 1826 methods->at_put(i, new_method()); 1827 } 1828 if (HAS_PENDING_EXCEPTION) { 1829 Symbol* ex_name = PENDING_EXCEPTION->klass()->name(); 1830 log_info(redefine, class, load, exceptions)("rewrite_cp_refs_in_method exception: '%s'", ex_name->as_C_string()); 1831 // Need to clear pending exception here as the super caller sets 1832 // the JVMTI_ERROR_INTERNAL if the returned value is false. 1833 CLEAR_PENDING_EXCEPTION; 1834 return false; 1835 } 1836 } 1837 1838 return true; 1839 } 1840 1841 1842 // Rewrite constant pool references in the specific method. This code 1843 // was adapted from Rewriter::rewrite_method(). 1844 void VM_RedefineClasses::rewrite_cp_refs_in_method(methodHandle method, 1845 methodHandle *new_method_p, TRAPS) { 1846 1847 *new_method_p = methodHandle(); // default is no new method 1848 1849 // We cache a pointer to the bytecodes here in code_base. If GC 1850 // moves the Method*, then the bytecodes will also move which 1851 // will likely cause a crash. We create a NoSafepointVerifier 1852 // object to detect whether we pass a possible safepoint in this 1853 // code block. 1854 NoSafepointVerifier nsv; 1855 1856 // Bytecodes and their length 1857 address code_base = method->code_base(); 1858 int code_length = method->code_size(); 1859 1860 int bc_length; 1861 for (int bci = 0; bci < code_length; bci += bc_length) { 1862 address bcp = code_base + bci; 1863 Bytecodes::Code c = (Bytecodes::Code)(*bcp); 1864 1865 bc_length = Bytecodes::length_for(c); 1866 if (bc_length == 0) { 1867 // More complicated bytecodes report a length of zero so 1868 // we have to try again a slightly different way. 1869 bc_length = Bytecodes::length_at(method(), bcp); 1870 } 1871 1872 assert(bc_length != 0, "impossible bytecode length"); 1873 1874 switch (c) { 1875 case Bytecodes::_ldc: 1876 { 1877 int cp_index = *(bcp + 1); 1878 int new_index = find_new_index(cp_index); 1879 1880 if (StressLdcRewrite && new_index == 0) { 1881 // If we are stressing ldc -> ldc_w rewriting, then we 1882 // always need a new_index value. 1883 new_index = cp_index; 1884 } 1885 if (new_index != 0) { 1886 // the original index is mapped so we have more work to do 1887 if (!StressLdcRewrite && new_index <= max_jubyte) { 1888 // The new value can still use ldc instead of ldc_w 1889 // unless we are trying to stress ldc -> ldc_w rewriting 1890 log_trace(redefine, class, constantpool) 1891 ("%s@" INTPTR_FORMAT " old=%d, new=%d", Bytecodes::name(c), p2i(bcp), cp_index, new_index); 1892 *(bcp + 1) = new_index; 1893 } else { 1894 log_trace(redefine, class, constantpool) 1895 ("%s->ldc_w@" INTPTR_FORMAT " old=%d, new=%d", Bytecodes::name(c), p2i(bcp), cp_index, new_index); 1896 // the new value needs ldc_w instead of ldc 1897 u_char inst_buffer[4]; // max instruction size is 4 bytes 1898 bcp = (address)inst_buffer; 1899 // construct new instruction sequence 1900 *bcp = Bytecodes::_ldc_w; 1901 bcp++; 1902 // Rewriter::rewrite_method() does not rewrite ldc -> ldc_w. 1903 // See comment below for difference between put_Java_u2() 1904 // and put_native_u2(). 1905 Bytes::put_Java_u2(bcp, new_index); 1906 1907 Relocator rc(method, NULL /* no RelocatorListener needed */); 1908 methodHandle m; 1909 { 1910 PauseNoSafepointVerifier pnsv(&nsv); 1911 1912 // ldc is 2 bytes and ldc_w is 3 bytes 1913 m = rc.insert_space_at(bci, 3, inst_buffer, CHECK); 1914 } 1915 1916 // return the new method so that the caller can update 1917 // the containing class 1918 *new_method_p = method = m; 1919 // switch our bytecode processing loop from the old method 1920 // to the new method 1921 code_base = method->code_base(); 1922 code_length = method->code_size(); 1923 bcp = code_base + bci; 1924 c = (Bytecodes::Code)(*bcp); 1925 bc_length = Bytecodes::length_for(c); 1926 assert(bc_length != 0, "sanity check"); 1927 } // end we need ldc_w instead of ldc 1928 } // end if there is a mapped index 1929 } break; 1930 1931 // these bytecodes have a two-byte constant pool index 1932 case Bytecodes::_anewarray : // fall through 1933 case Bytecodes::_checkcast : // fall through 1934 case Bytecodes::_getfield : // fall through 1935 case Bytecodes::_getstatic : // fall through 1936 case Bytecodes::_instanceof : // fall through 1937 case Bytecodes::_invokedynamic : // fall through 1938 case Bytecodes::_invokeinterface: // fall through 1939 case Bytecodes::_invokespecial : // fall through 1940 case Bytecodes::_invokestatic : // fall through 1941 case Bytecodes::_invokevirtual : // fall through 1942 case Bytecodes::_ldc_w : // fall through 1943 case Bytecodes::_ldc2_w : // fall through 1944 case Bytecodes::_multianewarray : // fall through 1945 case Bytecodes::_new : // fall through 1946 case Bytecodes::_putfield : // fall through 1947 case Bytecodes::_putstatic : 1948 { 1949 address p = bcp + 1; 1950 int cp_index = Bytes::get_Java_u2(p); 1951 int new_index = find_new_index(cp_index); 1952 if (new_index != 0) { 1953 // the original index is mapped so update w/ new value 1954 log_trace(redefine, class, constantpool) 1955 ("%s@" INTPTR_FORMAT " old=%d, new=%d", Bytecodes::name(c),p2i(bcp), cp_index, new_index); 1956 // Rewriter::rewrite_method() uses put_native_u2() in this 1957 // situation because it is reusing the constant pool index 1958 // location for a native index into the ConstantPoolCache. 1959 // Since we are updating the constant pool index prior to 1960 // verification and ConstantPoolCache initialization, we 1961 // need to keep the new index in Java byte order. 1962 Bytes::put_Java_u2(p, new_index); 1963 } 1964 } break; 1965 default: 1966 break; 1967 } 1968 } // end for each bytecode 1969 1970 // We also need to rewrite the parameter name indexes, if there is 1971 // method parameter data present 1972 if(method->has_method_parameters()) { 1973 const int len = method->method_parameters_length(); 1974 MethodParametersElement* elem = method->method_parameters_start(); 1975 1976 for (int i = 0; i < len; i++) { 1977 const u2 cp_index = elem[i].name_cp_index; 1978 const u2 new_cp_index = find_new_index(cp_index); 1979 if (new_cp_index != 0) { 1980 elem[i].name_cp_index = new_cp_index; 1981 } 1982 } 1983 } 1984 } // end rewrite_cp_refs_in_method() 1985 1986 1987 // Rewrite constant pool references in the class_annotations field. 1988 bool VM_RedefineClasses::rewrite_cp_refs_in_class_annotations( 1989 InstanceKlass* scratch_class, TRAPS) { 1990 1991 AnnotationArray* class_annotations = scratch_class->class_annotations(); 1992 if (class_annotations == NULL || class_annotations->length() == 0) { 1993 // no class_annotations so nothing to do 1994 return true; 1995 } 1996 1997 log_debug(redefine, class, annotation)("class_annotations length=%d", class_annotations->length()); 1998 1999 int byte_i = 0; // byte index into class_annotations 2000 return rewrite_cp_refs_in_annotations_typeArray(class_annotations, byte_i, 2001 THREAD); 2002 } 2003 2004 2005 // Rewrite constant pool references in an annotations typeArray. This 2006 // "structure" is adapted from the RuntimeVisibleAnnotations_attribute 2007 // that is described in section 4.8.15 of the 2nd-edition of the VM spec: 2008 // 2009 // annotations_typeArray { 2010 // u2 num_annotations; 2011 // annotation annotations[num_annotations]; 2012 // } 2013 // 2014 bool VM_RedefineClasses::rewrite_cp_refs_in_annotations_typeArray( 2015 AnnotationArray* annotations_typeArray, int &byte_i_ref, TRAPS) { 2016 2017 if ((byte_i_ref + 2) > annotations_typeArray->length()) { 2018 // not enough room for num_annotations field 2019 log_debug(redefine, class, annotation)("length() is too small for num_annotations field"); 2020 return false; 2021 } 2022 2023 u2 num_annotations = Bytes::get_Java_u2((address) 2024 annotations_typeArray->adr_at(byte_i_ref)); 2025 byte_i_ref += 2; 2026 2027 log_debug(redefine, class, annotation)("num_annotations=%d", num_annotations); 2028 2029 int calc_num_annotations = 0; 2030 for (; calc_num_annotations < num_annotations; calc_num_annotations++) { 2031 if (!rewrite_cp_refs_in_annotation_struct(annotations_typeArray, 2032 byte_i_ref, THREAD)) { 2033 log_debug(redefine, class, annotation)("bad annotation_struct at %d", calc_num_annotations); 2034 // propagate failure back to caller 2035 return false; 2036 } 2037 } 2038 assert(num_annotations == calc_num_annotations, "sanity check"); 2039 2040 return true; 2041 } // end rewrite_cp_refs_in_annotations_typeArray() 2042 2043 2044 // Rewrite constant pool references in the annotation struct portion of 2045 // an annotations_typeArray. This "structure" is from section 4.8.15 of 2046 // the 2nd-edition of the VM spec: 2047 // 2048 // struct annotation { 2049 // u2 type_index; 2050 // u2 num_element_value_pairs; 2051 // { 2052 // u2 element_name_index; 2053 // element_value value; 2054 // } element_value_pairs[num_element_value_pairs]; 2055 // } 2056 // 2057 bool VM_RedefineClasses::rewrite_cp_refs_in_annotation_struct( 2058 AnnotationArray* annotations_typeArray, int &byte_i_ref, TRAPS) { 2059 if ((byte_i_ref + 2 + 2) > annotations_typeArray->length()) { 2060 // not enough room for smallest annotation_struct 2061 log_debug(redefine, class, annotation)("length() is too small for annotation_struct"); 2062 return false; 2063 } 2064 2065 u2 type_index = rewrite_cp_ref_in_annotation_data(annotations_typeArray, 2066 byte_i_ref, "type_index", THREAD); 2067 2068 u2 num_element_value_pairs = Bytes::get_Java_u2((address) 2069 annotations_typeArray->adr_at(byte_i_ref)); 2070 byte_i_ref += 2; 2071 2072 log_debug(redefine, class, annotation) 2073 ("type_index=%d num_element_value_pairs=%d", type_index, num_element_value_pairs); 2074 2075 int calc_num_element_value_pairs = 0; 2076 for (; calc_num_element_value_pairs < num_element_value_pairs; 2077 calc_num_element_value_pairs++) { 2078 if ((byte_i_ref + 2) > annotations_typeArray->length()) { 2079 // not enough room for another element_name_index, let alone 2080 // the rest of another component 2081 log_debug(redefine, class, annotation)("length() is too small for element_name_index"); 2082 return false; 2083 } 2084 2085 u2 element_name_index = rewrite_cp_ref_in_annotation_data( 2086 annotations_typeArray, byte_i_ref, 2087 "element_name_index", THREAD); 2088 2089 log_debug(redefine, class, annotation)("element_name_index=%d", element_name_index); 2090 2091 if (!rewrite_cp_refs_in_element_value(annotations_typeArray, 2092 byte_i_ref, THREAD)) { 2093 log_debug(redefine, class, annotation)("bad element_value at %d", calc_num_element_value_pairs); 2094 // propagate failure back to caller 2095 return false; 2096 } 2097 } // end for each component 2098 assert(num_element_value_pairs == calc_num_element_value_pairs, 2099 "sanity check"); 2100 2101 return true; 2102 } // end rewrite_cp_refs_in_annotation_struct() 2103 2104 2105 // Rewrite a constant pool reference at the current position in 2106 // annotations_typeArray if needed. Returns the original constant 2107 // pool reference if a rewrite was not needed or the new constant 2108 // pool reference if a rewrite was needed. 2109 u2 VM_RedefineClasses::rewrite_cp_ref_in_annotation_data( 2110 AnnotationArray* annotations_typeArray, int &byte_i_ref, 2111 const char * trace_mesg, TRAPS) { 2112 2113 address cp_index_addr = (address) 2114 annotations_typeArray->adr_at(byte_i_ref); 2115 u2 old_cp_index = Bytes::get_Java_u2(cp_index_addr); 2116 u2 new_cp_index = find_new_index(old_cp_index); 2117 if (new_cp_index != 0) { 2118 log_debug(redefine, class, annotation)("mapped old %s=%d", trace_mesg, old_cp_index); 2119 Bytes::put_Java_u2(cp_index_addr, new_cp_index); 2120 old_cp_index = new_cp_index; 2121 } 2122 byte_i_ref += 2; 2123 return old_cp_index; 2124 } 2125 2126 2127 // Rewrite constant pool references in the element_value portion of an 2128 // annotations_typeArray. This "structure" is from section 4.8.15.1 of 2129 // the 2nd-edition of the VM spec: 2130 // 2131 // struct element_value { 2132 // u1 tag; 2133 // union { 2134 // u2 const_value_index; 2135 // { 2136 // u2 type_name_index; 2137 // u2 const_name_index; 2138 // } enum_const_value; 2139 // u2 class_info_index; 2140 // annotation annotation_value; 2141 // struct { 2142 // u2 num_values; 2143 // element_value values[num_values]; 2144 // } array_value; 2145 // } value; 2146 // } 2147 // 2148 bool VM_RedefineClasses::rewrite_cp_refs_in_element_value( 2149 AnnotationArray* annotations_typeArray, int &byte_i_ref, TRAPS) { 2150 2151 if ((byte_i_ref + 1) > annotations_typeArray->length()) { 2152 // not enough room for a tag let alone the rest of an element_value 2153 log_debug(redefine, class, annotation)("length() is too small for a tag"); 2154 return false; 2155 } 2156 2157 u1 tag = annotations_typeArray->at(byte_i_ref); 2158 byte_i_ref++; 2159 log_debug(redefine, class, annotation)("tag='%c'", tag); 2160 2161 switch (tag) { 2162 // These BaseType tag values are from Table 4.2 in VM spec: 2163 case 'B': // byte 2164 case 'C': // char 2165 case 'D': // double 2166 case 'F': // float 2167 case 'I': // int 2168 case 'J': // long 2169 case 'S': // short 2170 case 'Z': // boolean 2171 2172 // The remaining tag values are from Table 4.8 in the 2nd-edition of 2173 // the VM spec: 2174 case 's': 2175 { 2176 // For the above tag values (including the BaseType values), 2177 // value.const_value_index is right union field. 2178 2179 if ((byte_i_ref + 2) > annotations_typeArray->length()) { 2180 // not enough room for a const_value_index 2181 log_debug(redefine, class, annotation)("length() is too small for a const_value_index"); 2182 return false; 2183 } 2184 2185 u2 const_value_index = rewrite_cp_ref_in_annotation_data( 2186 annotations_typeArray, byte_i_ref, 2187 "const_value_index", THREAD); 2188 2189 log_debug(redefine, class, annotation)("const_value_index=%d", const_value_index); 2190 } break; 2191 2192 case 'e': 2193 { 2194 // for the above tag value, value.enum_const_value is right union field 2195 2196 if ((byte_i_ref + 4) > annotations_typeArray->length()) { 2197 // not enough room for a enum_const_value 2198 log_debug(redefine, class, annotation)("length() is too small for a enum_const_value"); 2199 return false; 2200 } 2201 2202 u2 type_name_index = rewrite_cp_ref_in_annotation_data( 2203 annotations_typeArray, byte_i_ref, 2204 "type_name_index", THREAD); 2205 2206 u2 const_name_index = rewrite_cp_ref_in_annotation_data( 2207 annotations_typeArray, byte_i_ref, 2208 "const_name_index", THREAD); 2209 2210 log_debug(redefine, class, annotation) 2211 ("type_name_index=%d const_name_index=%d", type_name_index, const_name_index); 2212 } break; 2213 2214 case 'c': 2215 { 2216 // for the above tag value, value.class_info_index is right union field 2217 2218 if ((byte_i_ref + 2) > annotations_typeArray->length()) { 2219 // not enough room for a class_info_index 2220 log_debug(redefine, class, annotation)("length() is too small for a class_info_index"); 2221 return false; 2222 } 2223 2224 u2 class_info_index = rewrite_cp_ref_in_annotation_data( 2225 annotations_typeArray, byte_i_ref, 2226 "class_info_index", THREAD); 2227 2228 log_debug(redefine, class, annotation)("class_info_index=%d", class_info_index); 2229 } break; 2230 2231 case '@': 2232 // For the above tag value, value.attr_value is the right union 2233 // field. This is a nested annotation. 2234 if (!rewrite_cp_refs_in_annotation_struct(annotations_typeArray, 2235 byte_i_ref, THREAD)) { 2236 // propagate failure back to caller 2237 return false; 2238 } 2239 break; 2240 2241 case '[': 2242 { 2243 if ((byte_i_ref + 2) > annotations_typeArray->length()) { 2244 // not enough room for a num_values field 2245 log_debug(redefine, class, annotation)("length() is too small for a num_values field"); 2246 return false; 2247 } 2248 2249 // For the above tag value, value.array_value is the right union 2250 // field. This is an array of nested element_value. 2251 u2 num_values = Bytes::get_Java_u2((address) 2252 annotations_typeArray->adr_at(byte_i_ref)); 2253 byte_i_ref += 2; 2254 log_debug(redefine, class, annotation)("num_values=%d", num_values); 2255 2256 int calc_num_values = 0; 2257 for (; calc_num_values < num_values; calc_num_values++) { 2258 if (!rewrite_cp_refs_in_element_value( 2259 annotations_typeArray, byte_i_ref, THREAD)) { 2260 log_debug(redefine, class, annotation)("bad nested element_value at %d", calc_num_values); 2261 // propagate failure back to caller 2262 return false; 2263 } 2264 } 2265 assert(num_values == calc_num_values, "sanity check"); 2266 } break; 2267 2268 default: 2269 log_debug(redefine, class, annotation)("bad tag=0x%x", tag); 2270 return false; 2271 } // end decode tag field 2272 2273 return true; 2274 } // end rewrite_cp_refs_in_element_value() 2275 2276 2277 // Rewrite constant pool references in a fields_annotations field. 2278 bool VM_RedefineClasses::rewrite_cp_refs_in_fields_annotations( 2279 InstanceKlass* scratch_class, TRAPS) { 2280 2281 Array<AnnotationArray*>* fields_annotations = scratch_class->fields_annotations(); 2282 2283 if (fields_annotations == NULL || fields_annotations->length() == 0) { 2284 // no fields_annotations so nothing to do 2285 return true; 2286 } 2287 2288 log_debug(redefine, class, annotation)("fields_annotations length=%d", fields_annotations->length()); 2289 2290 for (int i = 0; i < fields_annotations->length(); i++) { 2291 AnnotationArray* field_annotations = fields_annotations->at(i); 2292 if (field_annotations == NULL || field_annotations->length() == 0) { 2293 // this field does not have any annotations so skip it 2294 continue; 2295 } 2296 2297 int byte_i = 0; // byte index into field_annotations 2298 if (!rewrite_cp_refs_in_annotations_typeArray(field_annotations, byte_i, 2299 THREAD)) { 2300 log_debug(redefine, class, annotation)("bad field_annotations at %d", i); 2301 // propagate failure back to caller 2302 return false; 2303 } 2304 } 2305 2306 return true; 2307 } // end rewrite_cp_refs_in_fields_annotations() 2308 2309 2310 // Rewrite constant pool references in a methods_annotations field. 2311 bool VM_RedefineClasses::rewrite_cp_refs_in_methods_annotations( 2312 InstanceKlass* scratch_class, TRAPS) { 2313 2314 for (int i = 0; i < scratch_class->methods()->length(); i++) { 2315 Method* m = scratch_class->methods()->at(i); 2316 AnnotationArray* method_annotations = m->constMethod()->method_annotations(); 2317 2318 if (method_annotations == NULL || method_annotations->length() == 0) { 2319 // this method does not have any annotations so skip it 2320 continue; 2321 } 2322 2323 int byte_i = 0; // byte index into method_annotations 2324 if (!rewrite_cp_refs_in_annotations_typeArray(method_annotations, byte_i, 2325 THREAD)) { 2326 log_debug(redefine, class, annotation)("bad method_annotations at %d", i); 2327 // propagate failure back to caller 2328 return false; 2329 } 2330 } 2331 2332 return true; 2333 } // end rewrite_cp_refs_in_methods_annotations() 2334 2335 2336 // Rewrite constant pool references in a methods_parameter_annotations 2337 // field. This "structure" is adapted from the 2338 // RuntimeVisibleParameterAnnotations_attribute described in section 2339 // 4.8.17 of the 2nd-edition of the VM spec: 2340 // 2341 // methods_parameter_annotations_typeArray { 2342 // u1 num_parameters; 2343 // { 2344 // u2 num_annotations; 2345 // annotation annotations[num_annotations]; 2346 // } parameter_annotations[num_parameters]; 2347 // } 2348 // 2349 bool VM_RedefineClasses::rewrite_cp_refs_in_methods_parameter_annotations( 2350 InstanceKlass* scratch_class, TRAPS) { 2351 2352 for (int i = 0; i < scratch_class->methods()->length(); i++) { 2353 Method* m = scratch_class->methods()->at(i); 2354 AnnotationArray* method_parameter_annotations = m->constMethod()->parameter_annotations(); 2355 if (method_parameter_annotations == NULL 2356 || method_parameter_annotations->length() == 0) { 2357 // this method does not have any parameter annotations so skip it 2358 continue; 2359 } 2360 2361 if (method_parameter_annotations->length() < 1) { 2362 // not enough room for a num_parameters field 2363 log_debug(redefine, class, annotation)("length() is too small for a num_parameters field at %d", i); 2364 return false; 2365 } 2366 2367 int byte_i = 0; // byte index into method_parameter_annotations 2368 2369 u1 num_parameters = method_parameter_annotations->at(byte_i); 2370 byte_i++; 2371 2372 log_debug(redefine, class, annotation)("num_parameters=%d", num_parameters); 2373 2374 int calc_num_parameters = 0; 2375 for (; calc_num_parameters < num_parameters; calc_num_parameters++) { 2376 if (!rewrite_cp_refs_in_annotations_typeArray( 2377 method_parameter_annotations, byte_i, THREAD)) { 2378 log_debug(redefine, class, annotation)("bad method_parameter_annotations at %d", calc_num_parameters); 2379 // propagate failure back to caller 2380 return false; 2381 } 2382 } 2383 assert(num_parameters == calc_num_parameters, "sanity check"); 2384 } 2385 2386 return true; 2387 } // end rewrite_cp_refs_in_methods_parameter_annotations() 2388 2389 2390 // Rewrite constant pool references in a methods_default_annotations 2391 // field. This "structure" is adapted from the AnnotationDefault_attribute 2392 // that is described in section 4.8.19 of the 2nd-edition of the VM spec: 2393 // 2394 // methods_default_annotations_typeArray { 2395 // element_value default_value; 2396 // } 2397 // 2398 bool VM_RedefineClasses::rewrite_cp_refs_in_methods_default_annotations( 2399 InstanceKlass* scratch_class, TRAPS) { 2400 2401 for (int i = 0; i < scratch_class->methods()->length(); i++) { 2402 Method* m = scratch_class->methods()->at(i); 2403 AnnotationArray* method_default_annotations = m->constMethod()->default_annotations(); 2404 if (method_default_annotations == NULL 2405 || method_default_annotations->length() == 0) { 2406 // this method does not have any default annotations so skip it 2407 continue; 2408 } 2409 2410 int byte_i = 0; // byte index into method_default_annotations 2411 2412 if (!rewrite_cp_refs_in_element_value( 2413 method_default_annotations, byte_i, THREAD)) { 2414 log_debug(redefine, class, annotation)("bad default element_value at %d", i); 2415 // propagate failure back to caller 2416 return false; 2417 } 2418 } 2419 2420 return true; 2421 } // end rewrite_cp_refs_in_methods_default_annotations() 2422 2423 2424 // Rewrite constant pool references in a class_type_annotations field. 2425 bool VM_RedefineClasses::rewrite_cp_refs_in_class_type_annotations( 2426 InstanceKlass* scratch_class, TRAPS) { 2427 2428 AnnotationArray* class_type_annotations = scratch_class->class_type_annotations(); 2429 if (class_type_annotations == NULL || class_type_annotations->length() == 0) { 2430 // no class_type_annotations so nothing to do 2431 return true; 2432 } 2433 2434 log_debug(redefine, class, annotation)("class_type_annotations length=%d", class_type_annotations->length()); 2435 2436 int byte_i = 0; // byte index into class_type_annotations 2437 return rewrite_cp_refs_in_type_annotations_typeArray(class_type_annotations, 2438 byte_i, "ClassFile", THREAD); 2439 } // end rewrite_cp_refs_in_class_type_annotations() 2440 2441 2442 // Rewrite constant pool references in a fields_type_annotations field. 2443 bool VM_RedefineClasses::rewrite_cp_refs_in_fields_type_annotations( 2444 InstanceKlass* scratch_class, TRAPS) { 2445 2446 Array<AnnotationArray*>* fields_type_annotations = scratch_class->fields_type_annotations(); 2447 if (fields_type_annotations == NULL || fields_type_annotations->length() == 0) { 2448 // no fields_type_annotations so nothing to do 2449 return true; 2450 } 2451 2452 log_debug(redefine, class, annotation)("fields_type_annotations length=%d", fields_type_annotations->length()); 2453 2454 for (int i = 0; i < fields_type_annotations->length(); i++) { 2455 AnnotationArray* field_type_annotations = fields_type_annotations->at(i); 2456 if (field_type_annotations == NULL || field_type_annotations->length() == 0) { 2457 // this field does not have any annotations so skip it 2458 continue; 2459 } 2460 2461 int byte_i = 0; // byte index into field_type_annotations 2462 if (!rewrite_cp_refs_in_type_annotations_typeArray(field_type_annotations, 2463 byte_i, "field_info", THREAD)) { 2464 log_debug(redefine, class, annotation)("bad field_type_annotations at %d", i); 2465 // propagate failure back to caller 2466 return false; 2467 } 2468 } 2469 2470 return true; 2471 } // end rewrite_cp_refs_in_fields_type_annotations() 2472 2473 2474 // Rewrite constant pool references in a methods_type_annotations field. 2475 bool VM_RedefineClasses::rewrite_cp_refs_in_methods_type_annotations( 2476 InstanceKlass* scratch_class, TRAPS) { 2477 2478 for (int i = 0; i < scratch_class->methods()->length(); i++) { 2479 Method* m = scratch_class->methods()->at(i); 2480 AnnotationArray* method_type_annotations = m->constMethod()->type_annotations(); 2481 2482 if (method_type_annotations == NULL || method_type_annotations->length() == 0) { 2483 // this method does not have any annotations so skip it 2484 continue; 2485 } 2486 2487 log_debug(redefine, class, annotation)("methods type_annotations length=%d", method_type_annotations->length()); 2488 2489 int byte_i = 0; // byte index into method_type_annotations 2490 if (!rewrite_cp_refs_in_type_annotations_typeArray(method_type_annotations, 2491 byte_i, "method_info", THREAD)) { 2492 log_debug(redefine, class, annotation)("bad method_type_annotations at %d", i); 2493 // propagate failure back to caller 2494 return false; 2495 } 2496 } 2497 2498 return true; 2499 } // end rewrite_cp_refs_in_methods_type_annotations() 2500 2501 2502 // Rewrite constant pool references in a type_annotations 2503 // field. This "structure" is adapted from the 2504 // RuntimeVisibleTypeAnnotations_attribute described in 2505 // section 4.7.20 of the Java SE 8 Edition of the VM spec: 2506 // 2507 // type_annotations_typeArray { 2508 // u2 num_annotations; 2509 // type_annotation annotations[num_annotations]; 2510 // } 2511 // 2512 bool VM_RedefineClasses::rewrite_cp_refs_in_type_annotations_typeArray( 2513 AnnotationArray* type_annotations_typeArray, int &byte_i_ref, 2514 const char * location_mesg, TRAPS) { 2515 2516 if ((byte_i_ref + 2) > type_annotations_typeArray->length()) { 2517 // not enough room for num_annotations field 2518 log_debug(redefine, class, annotation)("length() is too small for num_annotations field"); 2519 return false; 2520 } 2521 2522 u2 num_annotations = Bytes::get_Java_u2((address) 2523 type_annotations_typeArray->adr_at(byte_i_ref)); 2524 byte_i_ref += 2; 2525 2526 log_debug(redefine, class, annotation)("num_type_annotations=%d", num_annotations); 2527 2528 int calc_num_annotations = 0; 2529 for (; calc_num_annotations < num_annotations; calc_num_annotations++) { 2530 if (!rewrite_cp_refs_in_type_annotation_struct(type_annotations_typeArray, 2531 byte_i_ref, location_mesg, THREAD)) { 2532 log_debug(redefine, class, annotation)("bad type_annotation_struct at %d", calc_num_annotations); 2533 // propagate failure back to caller 2534 return false; 2535 } 2536 } 2537 assert(num_annotations == calc_num_annotations, "sanity check"); 2538 2539 if (byte_i_ref != type_annotations_typeArray->length()) { 2540 log_debug(redefine, class, annotation) 2541 ("read wrong amount of bytes at end of processing type_annotations_typeArray (%d of %d bytes were read)", 2542 byte_i_ref, type_annotations_typeArray->length()); 2543 return false; 2544 } 2545 2546 return true; 2547 } // end rewrite_cp_refs_in_type_annotations_typeArray() 2548 2549 2550 // Rewrite constant pool references in a type_annotation 2551 // field. This "structure" is adapted from the 2552 // RuntimeVisibleTypeAnnotations_attribute described in 2553 // section 4.7.20 of the Java SE 8 Edition of the VM spec: 2554 // 2555 // type_annotation { 2556 // u1 target_type; 2557 // union { 2558 // type_parameter_target; 2559 // supertype_target; 2560 // type_parameter_bound_target; 2561 // empty_target; 2562 // method_formal_parameter_target; 2563 // throws_target; 2564 // localvar_target; 2565 // catch_target; 2566 // offset_target; 2567 // type_argument_target; 2568 // } target_info; 2569 // type_path target_path; 2570 // annotation anno; 2571 // } 2572 // 2573 bool VM_RedefineClasses::rewrite_cp_refs_in_type_annotation_struct( 2574 AnnotationArray* type_annotations_typeArray, int &byte_i_ref, 2575 const char * location_mesg, TRAPS) { 2576 2577 if (!skip_type_annotation_target(type_annotations_typeArray, 2578 byte_i_ref, location_mesg, THREAD)) { 2579 return false; 2580 } 2581 2582 if (!skip_type_annotation_type_path(type_annotations_typeArray, 2583 byte_i_ref, THREAD)) { 2584 return false; 2585 } 2586 2587 if (!rewrite_cp_refs_in_annotation_struct(type_annotations_typeArray, 2588 byte_i_ref, THREAD)) { 2589 return false; 2590 } 2591 2592 return true; 2593 } // end rewrite_cp_refs_in_type_annotation_struct() 2594 2595 2596 // Read, verify and skip over the target_type and target_info part 2597 // so that rewriting can continue in the later parts of the struct. 2598 // 2599 // u1 target_type; 2600 // union { 2601 // type_parameter_target; 2602 // supertype_target; 2603 // type_parameter_bound_target; 2604 // empty_target; 2605 // method_formal_parameter_target; 2606 // throws_target; 2607 // localvar_target; 2608 // catch_target; 2609 // offset_target; 2610 // type_argument_target; 2611 // } target_info; 2612 // 2613 bool VM_RedefineClasses::skip_type_annotation_target( 2614 AnnotationArray* type_annotations_typeArray, int &byte_i_ref, 2615 const char * location_mesg, TRAPS) { 2616 2617 if ((byte_i_ref + 1) > type_annotations_typeArray->length()) { 2618 // not enough room for a target_type let alone the rest of a type_annotation 2619 log_debug(redefine, class, annotation)("length() is too small for a target_type"); 2620 return false; 2621 } 2622 2623 u1 target_type = type_annotations_typeArray->at(byte_i_ref); 2624 byte_i_ref += 1; 2625 log_debug(redefine, class, annotation)("target_type=0x%.2x", target_type); 2626 log_debug(redefine, class, annotation)("location=%s", location_mesg); 2627 2628 // Skip over target_info 2629 switch (target_type) { 2630 case 0x00: 2631 // kind: type parameter declaration of generic class or interface 2632 // location: ClassFile 2633 case 0x01: 2634 // kind: type parameter declaration of generic method or constructor 2635 // location: method_info 2636 2637 { 2638 // struct: 2639 // type_parameter_target { 2640 // u1 type_parameter_index; 2641 // } 2642 // 2643 if ((byte_i_ref + 1) > type_annotations_typeArray->length()) { 2644 log_debug(redefine, class, annotation)("length() is too small for a type_parameter_target"); 2645 return false; 2646 } 2647 2648 u1 type_parameter_index = type_annotations_typeArray->at(byte_i_ref); 2649 byte_i_ref += 1; 2650 2651 log_debug(redefine, class, annotation)("type_parameter_target: type_parameter_index=%d", type_parameter_index); 2652 } break; 2653 2654 case 0x10: 2655 // kind: type in extends clause of class or interface declaration 2656 // (including the direct superclass of an anonymous class declaration), 2657 // or in implements clause of interface declaration 2658 // location: ClassFile 2659 2660 { 2661 // struct: 2662 // supertype_target { 2663 // u2 supertype_index; 2664 // } 2665 // 2666 if ((byte_i_ref + 2) > type_annotations_typeArray->length()) { 2667 log_debug(redefine, class, annotation)("length() is too small for a supertype_target"); 2668 return false; 2669 } 2670 2671 u2 supertype_index = Bytes::get_Java_u2((address) 2672 type_annotations_typeArray->adr_at(byte_i_ref)); 2673 byte_i_ref += 2; 2674 2675 log_debug(redefine, class, annotation)("supertype_target: supertype_index=%d", supertype_index); 2676 } break; 2677 2678 case 0x11: 2679 // kind: type in bound of type parameter declaration of generic class or interface 2680 // location: ClassFile 2681 case 0x12: 2682 // kind: type in bound of type parameter declaration of generic method or constructor 2683 // location: method_info 2684 2685 { 2686 // struct: 2687 // type_parameter_bound_target { 2688 // u1 type_parameter_index; 2689 // u1 bound_index; 2690 // } 2691 // 2692 if ((byte_i_ref + 2) > type_annotations_typeArray->length()) { 2693 log_debug(redefine, class, annotation)("length() is too small for a type_parameter_bound_target"); 2694 return false; 2695 } 2696 2697 u1 type_parameter_index = type_annotations_typeArray->at(byte_i_ref); 2698 byte_i_ref += 1; 2699 u1 bound_index = type_annotations_typeArray->at(byte_i_ref); 2700 byte_i_ref += 1; 2701 2702 log_debug(redefine, class, annotation) 2703 ("type_parameter_bound_target: type_parameter_index=%d, bound_index=%d", type_parameter_index, bound_index); 2704 } break; 2705 2706 case 0x13: 2707 // kind: type in field declaration 2708 // location: field_info 2709 case 0x14: 2710 // kind: return type of method, or type of newly constructed object 2711 // location: method_info 2712 case 0x15: 2713 // kind: receiver type of method or constructor 2714 // location: method_info 2715 2716 { 2717 // struct: 2718 // empty_target { 2719 // } 2720 // 2721 log_debug(redefine, class, annotation)("empty_target"); 2722 } break; 2723 2724 case 0x16: 2725 // kind: type in formal parameter declaration of method, constructor, or lambda expression 2726 // location: method_info 2727 2728 { 2729 // struct: 2730 // formal_parameter_target { 2731 // u1 formal_parameter_index; 2732 // } 2733 // 2734 if ((byte_i_ref + 1) > type_annotations_typeArray->length()) { 2735 log_debug(redefine, class, annotation)("length() is too small for a formal_parameter_target"); 2736 return false; 2737 } 2738 2739 u1 formal_parameter_index = type_annotations_typeArray->at(byte_i_ref); 2740 byte_i_ref += 1; 2741 2742 log_debug(redefine, class, annotation) 2743 ("formal_parameter_target: formal_parameter_index=%d", formal_parameter_index); 2744 } break; 2745 2746 case 0x17: 2747 // kind: type in throws clause of method or constructor 2748 // location: method_info 2749 2750 { 2751 // struct: 2752 // throws_target { 2753 // u2 throws_type_index 2754 // } 2755 // 2756 if ((byte_i_ref + 2) > type_annotations_typeArray->length()) { 2757 log_debug(redefine, class, annotation)("length() is too small for a throws_target"); 2758 return false; 2759 } 2760 2761 u2 throws_type_index = Bytes::get_Java_u2((address) 2762 type_annotations_typeArray->adr_at(byte_i_ref)); 2763 byte_i_ref += 2; 2764 2765 log_debug(redefine, class, annotation)("throws_target: throws_type_index=%d", throws_type_index); 2766 } break; 2767 2768 case 0x40: 2769 // kind: type in local variable declaration 2770 // location: Code 2771 case 0x41: 2772 // kind: type in resource variable declaration 2773 // location: Code 2774 2775 { 2776 // struct: 2777 // localvar_target { 2778 // u2 table_length; 2779 // struct { 2780 // u2 start_pc; 2781 // u2 length; 2782 // u2 index; 2783 // } table[table_length]; 2784 // } 2785 // 2786 if ((byte_i_ref + 2) > type_annotations_typeArray->length()) { 2787 // not enough room for a table_length let alone the rest of a localvar_target 2788 log_debug(redefine, class, annotation)("length() is too small for a localvar_target table_length"); 2789 return false; 2790 } 2791 2792 u2 table_length = Bytes::get_Java_u2((address) 2793 type_annotations_typeArray->adr_at(byte_i_ref)); 2794 byte_i_ref += 2; 2795 2796 log_debug(redefine, class, annotation)("localvar_target: table_length=%d", table_length); 2797 2798 int table_struct_size = 2 + 2 + 2; // 3 u2 variables per table entry 2799 int table_size = table_length * table_struct_size; 2800 2801 if ((byte_i_ref + table_size) > type_annotations_typeArray->length()) { 2802 // not enough room for a table 2803 log_debug(redefine, class, annotation)("length() is too small for a table array of length %d", table_length); 2804 return false; 2805 } 2806 2807 // Skip over table 2808 byte_i_ref += table_size; 2809 } break; 2810 2811 case 0x42: 2812 // kind: type in exception parameter declaration 2813 // location: Code 2814 2815 { 2816 // struct: 2817 // catch_target { 2818 // u2 exception_table_index; 2819 // } 2820 // 2821 if ((byte_i_ref + 2) > type_annotations_typeArray->length()) { 2822 log_debug(redefine, class, annotation)("length() is too small for a catch_target"); 2823 return false; 2824 } 2825 2826 u2 exception_table_index = Bytes::get_Java_u2((address) 2827 type_annotations_typeArray->adr_at(byte_i_ref)); 2828 byte_i_ref += 2; 2829 2830 log_debug(redefine, class, annotation)("catch_target: exception_table_index=%d", exception_table_index); 2831 } break; 2832 2833 case 0x43: 2834 // kind: type in instanceof expression 2835 // location: Code 2836 case 0x44: 2837 // kind: type in new expression 2838 // location: Code 2839 case 0x45: 2840 // kind: type in method reference expression using ::new 2841 // location: Code 2842 case 0x46: 2843 // kind: type in method reference expression using ::Identifier 2844 // location: Code 2845 2846 { 2847 // struct: 2848 // offset_target { 2849 // u2 offset; 2850 // } 2851 // 2852 if ((byte_i_ref + 2) > type_annotations_typeArray->length()) { 2853 log_debug(redefine, class, annotation)("length() is too small for a offset_target"); 2854 return false; 2855 } 2856 2857 u2 offset = Bytes::get_Java_u2((address) 2858 type_annotations_typeArray->adr_at(byte_i_ref)); 2859 byte_i_ref += 2; 2860 2861 log_debug(redefine, class, annotation)("offset_target: offset=%d", offset); 2862 } break; 2863 2864 case 0x47: 2865 // kind: type in cast expression 2866 // location: Code 2867 case 0x48: 2868 // kind: type argument for generic constructor in new expression or 2869 // explicit constructor invocation statement 2870 // location: Code 2871 case 0x49: 2872 // kind: type argument for generic method in method invocation expression 2873 // location: Code 2874 case 0x4A: 2875 // kind: type argument for generic constructor in method reference expression using ::new 2876 // location: Code 2877 case 0x4B: 2878 // kind: type argument for generic method in method reference expression using ::Identifier 2879 // location: Code 2880 2881 { 2882 // struct: 2883 // type_argument_target { 2884 // u2 offset; 2885 // u1 type_argument_index; 2886 // } 2887 // 2888 if ((byte_i_ref + 3) > type_annotations_typeArray->length()) { 2889 log_debug(redefine, class, annotation)("length() is too small for a type_argument_target"); 2890 return false; 2891 } 2892 2893 u2 offset = Bytes::get_Java_u2((address) 2894 type_annotations_typeArray->adr_at(byte_i_ref)); 2895 byte_i_ref += 2; 2896 u1 type_argument_index = type_annotations_typeArray->at(byte_i_ref); 2897 byte_i_ref += 1; 2898 2899 log_debug(redefine, class, annotation) 2900 ("type_argument_target: offset=%d, type_argument_index=%d", offset, type_argument_index); 2901 } break; 2902 2903 default: 2904 log_debug(redefine, class, annotation)("unknown target_type"); 2905 #ifdef ASSERT 2906 ShouldNotReachHere(); 2907 #endif 2908 return false; 2909 } 2910 2911 return true; 2912 } // end skip_type_annotation_target() 2913 2914 2915 // Read, verify and skip over the type_path part so that rewriting 2916 // can continue in the later parts of the struct. 2917 // 2918 // type_path { 2919 // u1 path_length; 2920 // { 2921 // u1 type_path_kind; 2922 // u1 type_argument_index; 2923 // } path[path_length]; 2924 // } 2925 // 2926 bool VM_RedefineClasses::skip_type_annotation_type_path( 2927 AnnotationArray* type_annotations_typeArray, int &byte_i_ref, TRAPS) { 2928 2929 if ((byte_i_ref + 1) > type_annotations_typeArray->length()) { 2930 // not enough room for a path_length let alone the rest of the type_path 2931 log_debug(redefine, class, annotation)("length() is too small for a type_path"); 2932 return false; 2933 } 2934 2935 u1 path_length = type_annotations_typeArray->at(byte_i_ref); 2936 byte_i_ref += 1; 2937 2938 log_debug(redefine, class, annotation)("type_path: path_length=%d", path_length); 2939 2940 int calc_path_length = 0; 2941 for (; calc_path_length < path_length; calc_path_length++) { 2942 if ((byte_i_ref + 1 + 1) > type_annotations_typeArray->length()) { 2943 // not enough room for a path 2944 log_debug(redefine, class, annotation) 2945 ("length() is too small for path entry %d of %d", calc_path_length, path_length); 2946 return false; 2947 } 2948 2949 u1 type_path_kind = type_annotations_typeArray->at(byte_i_ref); 2950 byte_i_ref += 1; 2951 u1 type_argument_index = type_annotations_typeArray->at(byte_i_ref); 2952 byte_i_ref += 1; 2953 2954 log_debug(redefine, class, annotation) 2955 ("type_path: path[%d]: type_path_kind=%d, type_argument_index=%d", 2956 calc_path_length, type_path_kind, type_argument_index); 2957 2958 if (type_path_kind > 3 || (type_path_kind != 3 && type_argument_index != 0)) { 2959 // not enough room for a path 2960 log_debug(redefine, class, annotation)("inconsistent type_path values"); 2961 return false; 2962 } 2963 } 2964 assert(path_length == calc_path_length, "sanity check"); 2965 2966 return true; 2967 } // end skip_type_annotation_type_path() 2968 2969 2970 // Rewrite constant pool references in the method's stackmap table. 2971 // These "structures" are adapted from the StackMapTable_attribute that 2972 // is described in section 4.8.4 of the 6.0 version of the VM spec 2973 // (dated 2005.10.26): 2974 // file:///net/quincunx.sfbay/export/gbracha/ClassFile-Java6.pdf 2975 // 2976 // stack_map { 2977 // u2 number_of_entries; 2978 // stack_map_frame entries[number_of_entries]; 2979 // } 2980 // 2981 void VM_RedefineClasses::rewrite_cp_refs_in_stack_map_table( 2982 const methodHandle& method, TRAPS) { 2983 2984 if (!method->has_stackmap_table()) { 2985 return; 2986 } 2987 2988 AnnotationArray* stackmap_data = method->stackmap_data(); 2989 address stackmap_p = (address)stackmap_data->adr_at(0); 2990 address stackmap_end = stackmap_p + stackmap_data->length(); 2991 2992 assert(stackmap_p + 2 <= stackmap_end, "no room for number_of_entries"); 2993 u2 number_of_entries = Bytes::get_Java_u2(stackmap_p); 2994 stackmap_p += 2; 2995 2996 log_debug(redefine, class, stackmap)("number_of_entries=%u", number_of_entries); 2997 2998 // walk through each stack_map_frame 2999 u2 calc_number_of_entries = 0; 3000 for (; calc_number_of_entries < number_of_entries; calc_number_of_entries++) { 3001 // The stack_map_frame structure is a u1 frame_type followed by 3002 // 0 or more bytes of data: 3003 // 3004 // union stack_map_frame { 3005 // same_frame; 3006 // same_locals_1_stack_item_frame; 3007 // same_locals_1_stack_item_frame_extended; 3008 // chop_frame; 3009 // same_frame_extended; 3010 // append_frame; 3011 // full_frame; 3012 // } 3013 3014 assert(stackmap_p + 1 <= stackmap_end, "no room for frame_type"); 3015 u1 frame_type = *stackmap_p; 3016 stackmap_p++; 3017 3018 // same_frame { 3019 // u1 frame_type = SAME; /* 0-63 */ 3020 // } 3021 if (frame_type <= 63) { 3022 // nothing more to do for same_frame 3023 } 3024 3025 // same_locals_1_stack_item_frame { 3026 // u1 frame_type = SAME_LOCALS_1_STACK_ITEM; /* 64-127 */ 3027 // verification_type_info stack[1]; 3028 // } 3029 else if (frame_type >= 64 && frame_type <= 127) { 3030 rewrite_cp_refs_in_verification_type_info(stackmap_p, stackmap_end, 3031 calc_number_of_entries, frame_type, THREAD); 3032 } 3033 3034 // reserved for future use 3035 else if (frame_type >= 128 && frame_type <= 246) { 3036 // nothing more to do for reserved frame_types 3037 } 3038 3039 // same_locals_1_stack_item_frame_extended { 3040 // u1 frame_type = SAME_LOCALS_1_STACK_ITEM_EXTENDED; /* 247 */ 3041 // u2 offset_delta; 3042 // verification_type_info stack[1]; 3043 // } 3044 else if (frame_type == 247) { 3045 stackmap_p += 2; 3046 rewrite_cp_refs_in_verification_type_info(stackmap_p, stackmap_end, 3047 calc_number_of_entries, frame_type, THREAD); 3048 } 3049 3050 // chop_frame { 3051 // u1 frame_type = CHOP; /* 248-250 */ 3052 // u2 offset_delta; 3053 // } 3054 else if (frame_type >= 248 && frame_type <= 250) { 3055 stackmap_p += 2; 3056 } 3057 3058 // same_frame_extended { 3059 // u1 frame_type = SAME_FRAME_EXTENDED; /* 251*/ 3060 // u2 offset_delta; 3061 // } 3062 else if (frame_type == 251) { 3063 stackmap_p += 2; 3064 } 3065 3066 // append_frame { 3067 // u1 frame_type = APPEND; /* 252-254 */ 3068 // u2 offset_delta; 3069 // verification_type_info locals[frame_type - 251]; 3070 // } 3071 else if (frame_type >= 252 && frame_type <= 254) { 3072 assert(stackmap_p + 2 <= stackmap_end, 3073 "no room for offset_delta"); 3074 stackmap_p += 2; 3075 u1 len = frame_type - 251; 3076 for (u1 i = 0; i < len; i++) { 3077 rewrite_cp_refs_in_verification_type_info(stackmap_p, stackmap_end, 3078 calc_number_of_entries, frame_type, THREAD); 3079 } 3080 } 3081 3082 // full_frame { 3083 // u1 frame_type = FULL_FRAME; /* 255 */ 3084 // u2 offset_delta; 3085 // u2 number_of_locals; 3086 // verification_type_info locals[number_of_locals]; 3087 // u2 number_of_stack_items; 3088 // verification_type_info stack[number_of_stack_items]; 3089 // } 3090 else if (frame_type == 255) { 3091 assert(stackmap_p + 2 + 2 <= stackmap_end, 3092 "no room for smallest full_frame"); 3093 stackmap_p += 2; 3094 3095 u2 number_of_locals = Bytes::get_Java_u2(stackmap_p); 3096 stackmap_p += 2; 3097 3098 for (u2 locals_i = 0; locals_i < number_of_locals; locals_i++) { 3099 rewrite_cp_refs_in_verification_type_info(stackmap_p, stackmap_end, 3100 calc_number_of_entries, frame_type, THREAD); 3101 } 3102 3103 // Use the largest size for the number_of_stack_items, but only get 3104 // the right number of bytes. 3105 u2 number_of_stack_items = Bytes::get_Java_u2(stackmap_p); 3106 stackmap_p += 2; 3107 3108 for (u2 stack_i = 0; stack_i < number_of_stack_items; stack_i++) { 3109 rewrite_cp_refs_in_verification_type_info(stackmap_p, stackmap_end, 3110 calc_number_of_entries, frame_type, THREAD); 3111 } 3112 } 3113 } // end while there is a stack_map_frame 3114 assert(number_of_entries == calc_number_of_entries, "sanity check"); 3115 } // end rewrite_cp_refs_in_stack_map_table() 3116 3117 3118 // Rewrite constant pool references in the verification type info 3119 // portion of the method's stackmap table. These "structures" are 3120 // adapted from the StackMapTable_attribute that is described in 3121 // section 4.8.4 of the 6.0 version of the VM spec (dated 2005.10.26): 3122 // file:///net/quincunx.sfbay/export/gbracha/ClassFile-Java6.pdf 3123 // 3124 // The verification_type_info structure is a u1 tag followed by 0 or 3125 // more bytes of data: 3126 // 3127 // union verification_type_info { 3128 // Top_variable_info; 3129 // Integer_variable_info; 3130 // Float_variable_info; 3131 // Long_variable_info; 3132 // Double_variable_info; 3133 // Null_variable_info; 3134 // UninitializedThis_variable_info; 3135 // Object_variable_info; 3136 // Uninitialized_variable_info; 3137 // } 3138 // 3139 void VM_RedefineClasses::rewrite_cp_refs_in_verification_type_info( 3140 address& stackmap_p_ref, address stackmap_end, u2 frame_i, 3141 u1 frame_type, TRAPS) { 3142 3143 assert(stackmap_p_ref + 1 <= stackmap_end, "no room for tag"); 3144 u1 tag = *stackmap_p_ref; 3145 stackmap_p_ref++; 3146 3147 switch (tag) { 3148 // Top_variable_info { 3149 // u1 tag = ITEM_Top; /* 0 */ 3150 // } 3151 // verificationType.hpp has zero as ITEM_Bogus instead of ITEM_Top 3152 case 0: // fall through 3153 3154 // Integer_variable_info { 3155 // u1 tag = ITEM_Integer; /* 1 */ 3156 // } 3157 case ITEM_Integer: // fall through 3158 3159 // Float_variable_info { 3160 // u1 tag = ITEM_Float; /* 2 */ 3161 // } 3162 case ITEM_Float: // fall through 3163 3164 // Double_variable_info { 3165 // u1 tag = ITEM_Double; /* 3 */ 3166 // } 3167 case ITEM_Double: // fall through 3168 3169 // Long_variable_info { 3170 // u1 tag = ITEM_Long; /* 4 */ 3171 // } 3172 case ITEM_Long: // fall through 3173 3174 // Null_variable_info { 3175 // u1 tag = ITEM_Null; /* 5 */ 3176 // } 3177 case ITEM_Null: // fall through 3178 3179 // UninitializedThis_variable_info { 3180 // u1 tag = ITEM_UninitializedThis; /* 6 */ 3181 // } 3182 case ITEM_UninitializedThis: 3183 // nothing more to do for the above tag types 3184 break; 3185 3186 // Object_variable_info { 3187 // u1 tag = ITEM_Object; /* 7 */ 3188 // u2 cpool_index; 3189 // } 3190 case ITEM_Object: 3191 { 3192 assert(stackmap_p_ref + 2 <= stackmap_end, "no room for cpool_index"); 3193 u2 cpool_index = Bytes::get_Java_u2(stackmap_p_ref); 3194 u2 new_cp_index = find_new_index(cpool_index); 3195 if (new_cp_index != 0) { 3196 log_debug(redefine, class, stackmap)("mapped old cpool_index=%d", cpool_index); 3197 Bytes::put_Java_u2(stackmap_p_ref, new_cp_index); 3198 cpool_index = new_cp_index; 3199 } 3200 stackmap_p_ref += 2; 3201 3202 log_debug(redefine, class, stackmap) 3203 ("frame_i=%u, frame_type=%u, cpool_index=%d", frame_i, frame_type, cpool_index); 3204 } break; 3205 3206 // Uninitialized_variable_info { 3207 // u1 tag = ITEM_Uninitialized; /* 8 */ 3208 // u2 offset; 3209 // } 3210 case ITEM_Uninitialized: 3211 assert(stackmap_p_ref + 2 <= stackmap_end, "no room for offset"); 3212 stackmap_p_ref += 2; 3213 break; 3214 3215 default: 3216 log_debug(redefine, class, stackmap)("frame_i=%u, frame_type=%u, bad tag=0x%x", frame_i, frame_type, tag); 3217 ShouldNotReachHere(); 3218 break; 3219 } // end switch (tag) 3220 } // end rewrite_cp_refs_in_verification_type_info() 3221 3222 3223 // Change the constant pool associated with klass scratch_class to 3224 // scratch_cp. If shrink is true, then scratch_cp_length elements 3225 // are copied from scratch_cp to a smaller constant pool and the 3226 // smaller constant pool is associated with scratch_class. 3227 void VM_RedefineClasses::set_new_constant_pool( 3228 ClassLoaderData* loader_data, 3229 InstanceKlass* scratch_class, constantPoolHandle scratch_cp, 3230 int scratch_cp_length, TRAPS) { 3231 assert(scratch_cp->length() >= scratch_cp_length, "sanity check"); 3232 3233 // scratch_cp is a merged constant pool and has enough space for a 3234 // worst case merge situation. We want to associate the minimum 3235 // sized constant pool with the klass to save space. 3236 ConstantPool* cp = ConstantPool::allocate(loader_data, scratch_cp_length, CHECK); 3237 constantPoolHandle smaller_cp(THREAD, cp); 3238 3239 // preserve version() value in the smaller copy 3240 int version = scratch_cp->version(); 3241 assert(version != 0, "sanity check"); 3242 smaller_cp->set_version(version); 3243 3244 // attach klass to new constant pool 3245 // reference to the cp holder is needed for copy_operands() 3246 smaller_cp->set_pool_holder(scratch_class); 3247 3248 scratch_cp->copy_cp_to(1, scratch_cp_length - 1, smaller_cp, 1, THREAD); 3249 if (HAS_PENDING_EXCEPTION) { 3250 // Exception is handled in the caller 3251 loader_data->add_to_deallocate_list(smaller_cp()); 3252 return; 3253 } 3254 scratch_cp = smaller_cp; 3255 3256 // attach new constant pool to klass 3257 scratch_class->set_constants(scratch_cp()); 3258 scratch_cp->initialize_unresolved_klasses(loader_data, CHECK); 3259 3260 int i; // for portability 3261 3262 // update each field in klass to use new constant pool indices as needed 3263 for (JavaFieldStream fs(scratch_class); !fs.done(); fs.next()) { 3264 jshort cur_index = fs.name_index(); 3265 jshort new_index = find_new_index(cur_index); 3266 if (new_index != 0) { 3267 log_trace(redefine, class, constantpool)("field-name_index change: %d to %d", cur_index, new_index); 3268 fs.set_name_index(new_index); 3269 } 3270 cur_index = fs.signature_index(); 3271 new_index = find_new_index(cur_index); 3272 if (new_index != 0) { 3273 log_trace(redefine, class, constantpool)("field-signature_index change: %d to %d", cur_index, new_index); 3274 fs.set_signature_index(new_index); 3275 } 3276 cur_index = fs.initval_index(); 3277 new_index = find_new_index(cur_index); 3278 if (new_index != 0) { 3279 log_trace(redefine, class, constantpool)("field-initval_index change: %d to %d", cur_index, new_index); 3280 fs.set_initval_index(new_index); 3281 } 3282 cur_index = fs.generic_signature_index(); 3283 new_index = find_new_index(cur_index); 3284 if (new_index != 0) { 3285 log_trace(redefine, class, constantpool)("field-generic_signature change: %d to %d", cur_index, new_index); 3286 fs.set_generic_signature_index(new_index); 3287 } 3288 } // end for each field 3289 3290 // Update constant pool indices in the inner classes info to use 3291 // new constant indices as needed. The inner classes info is a 3292 // quadruple: 3293 // (inner_class_info, outer_class_info, inner_name, inner_access_flags) 3294 InnerClassesIterator iter(scratch_class); 3295 for (; !iter.done(); iter.next()) { 3296 int cur_index = iter.inner_class_info_index(); 3297 if (cur_index == 0) { 3298 continue; // JVM spec. allows null inner class refs so skip it 3299 } 3300 int new_index = find_new_index(cur_index); 3301 if (new_index != 0) { 3302 log_trace(redefine, class, constantpool)("inner_class_info change: %d to %d", cur_index, new_index); 3303 iter.set_inner_class_info_index(new_index); 3304 } 3305 cur_index = iter.outer_class_info_index(); 3306 new_index = find_new_index(cur_index); 3307 if (new_index != 0) { 3308 log_trace(redefine, class, constantpool)("outer_class_info change: %d to %d", cur_index, new_index); 3309 iter.set_outer_class_info_index(new_index); 3310 } 3311 cur_index = iter.inner_name_index(); 3312 new_index = find_new_index(cur_index); 3313 if (new_index != 0) { 3314 log_trace(redefine, class, constantpool)("inner_name change: %d to %d", cur_index, new_index); 3315 iter.set_inner_name_index(new_index); 3316 } 3317 } // end for each inner class 3318 3319 // Attach each method in klass to the new constant pool and update 3320 // to use new constant pool indices as needed: 3321 Array<Method*>* methods = scratch_class->methods(); 3322 for (i = methods->length() - 1; i >= 0; i--) { 3323 methodHandle method(THREAD, methods->at(i)); 3324 method->set_constants(scratch_cp()); 3325 3326 int new_index = find_new_index(method->name_index()); 3327 if (new_index != 0) { 3328 log_trace(redefine, class, constantpool) 3329 ("method-name_index change: %d to %d", method->name_index(), new_index); 3330 method->set_name_index(new_index); 3331 } 3332 new_index = find_new_index(method->signature_index()); 3333 if (new_index != 0) { 3334 log_trace(redefine, class, constantpool) 3335 ("method-signature_index change: %d to %d", method->signature_index(), new_index); 3336 method->set_signature_index(new_index); 3337 } 3338 new_index = find_new_index(method->generic_signature_index()); 3339 if (new_index != 0) { 3340 log_trace(redefine, class, constantpool) 3341 ("method-generic_signature_index change: %d to %d", method->generic_signature_index(), new_index); 3342 method->set_generic_signature_index(new_index); 3343 } 3344 3345 // Update constant pool indices in the method's checked exception 3346 // table to use new constant indices as needed. 3347 int cext_length = method->checked_exceptions_length(); 3348 if (cext_length > 0) { 3349 CheckedExceptionElement * cext_table = 3350 method->checked_exceptions_start(); 3351 for (int j = 0; j < cext_length; j++) { 3352 int cur_index = cext_table[j].class_cp_index; 3353 int new_index = find_new_index(cur_index); 3354 if (new_index != 0) { 3355 log_trace(redefine, class, constantpool)("cext-class_cp_index change: %d to %d", cur_index, new_index); 3356 cext_table[j].class_cp_index = (u2)new_index; 3357 } 3358 } // end for each checked exception table entry 3359 } // end if there are checked exception table entries 3360 3361 // Update each catch type index in the method's exception table 3362 // to use new constant pool indices as needed. The exception table 3363 // holds quadruple entries of the form: 3364 // (beg_bci, end_bci, handler_bci, klass_index) 3365 3366 ExceptionTable ex_table(method()); 3367 int ext_length = ex_table.length(); 3368 3369 for (int j = 0; j < ext_length; j ++) { 3370 int cur_index = ex_table.catch_type_index(j); 3371 int new_index = find_new_index(cur_index); 3372 if (new_index != 0) { 3373 log_trace(redefine, class, constantpool)("ext-klass_index change: %d to %d", cur_index, new_index); 3374 ex_table.set_catch_type_index(j, new_index); 3375 } 3376 } // end for each exception table entry 3377 3378 // Update constant pool indices in the method's local variable 3379 // table to use new constant indices as needed. The local variable 3380 // table hold sextuple entries of the form: 3381 // (start_pc, length, name_index, descriptor_index, signature_index, slot) 3382 int lvt_length = method->localvariable_table_length(); 3383 if (lvt_length > 0) { 3384 LocalVariableTableElement * lv_table = 3385 method->localvariable_table_start(); 3386 for (int j = 0; j < lvt_length; j++) { 3387 int cur_index = lv_table[j].name_cp_index; 3388 int new_index = find_new_index(cur_index); 3389 if (new_index != 0) { 3390 log_trace(redefine, class, constantpool)("lvt-name_cp_index change: %d to %d", cur_index, new_index); 3391 lv_table[j].name_cp_index = (u2)new_index; 3392 } 3393 cur_index = lv_table[j].descriptor_cp_index; 3394 new_index = find_new_index(cur_index); 3395 if (new_index != 0) { 3396 log_trace(redefine, class, constantpool)("lvt-descriptor_cp_index change: %d to %d", cur_index, new_index); 3397 lv_table[j].descriptor_cp_index = (u2)new_index; 3398 } 3399 cur_index = lv_table[j].signature_cp_index; 3400 new_index = find_new_index(cur_index); 3401 if (new_index != 0) { 3402 log_trace(redefine, class, constantpool)("lvt-signature_cp_index change: %d to %d", cur_index, new_index); 3403 lv_table[j].signature_cp_index = (u2)new_index; 3404 } 3405 } // end for each local variable table entry 3406 } // end if there are local variable table entries 3407 3408 rewrite_cp_refs_in_stack_map_table(method, THREAD); 3409 } // end for each method 3410 } // end set_new_constant_pool() 3411 3412 3413 // Unevolving classes may point to methods of the_class directly 3414 // from their constant pool caches, itables, and/or vtables. We 3415 // use the ClassLoaderDataGraph::classes_do() facility and this helper 3416 // to fix up these pointers. 3417 3418 // Adjust cpools and vtables closure 3419 void VM_RedefineClasses::AdjustCpoolCacheAndVtable::do_klass(Klass* k) { 3420 3421 // This is a very busy routine. We don't want too much tracing 3422 // printed out. 3423 bool trace_name_printed = false; 3424 InstanceKlass *the_class = InstanceKlass::cast(_the_class); 3425 3426 // If the class being redefined is java.lang.Object, we need to fix all 3427 // array class vtables also 3428 if (k->is_array_klass() && _the_class == SystemDictionary::Object_klass()) { 3429 k->vtable().adjust_method_entries(the_class, &trace_name_printed); 3430 3431 } else if (k->is_instance_klass()) { 3432 HandleMark hm(_thread); 3433 InstanceKlass *ik = InstanceKlass::cast(k); 3434 3435 // HotSpot specific optimization! HotSpot does not currently 3436 // support delegation from the bootstrap class loader to a 3437 // user-defined class loader. This means that if the bootstrap 3438 // class loader is the initiating class loader, then it will also 3439 // be the defining class loader. This also means that classes 3440 // loaded by the bootstrap class loader cannot refer to classes 3441 // loaded by a user-defined class loader. Note: a user-defined 3442 // class loader can delegate to the bootstrap class loader. 3443 // 3444 // If the current class being redefined has a user-defined class 3445 // loader as its defining class loader, then we can skip all 3446 // classes loaded by the bootstrap class loader. 3447 bool is_user_defined = (_the_class->class_loader() != NULL); 3448 if (is_user_defined && ik->class_loader() == NULL) { 3449 return; 3450 } 3451 3452 // Fix the vtable embedded in the_class and subclasses of the_class, 3453 // if one exists. We discard scratch_class and we don't keep an 3454 // InstanceKlass around to hold obsolete methods so we don't have 3455 // any other InstanceKlass embedded vtables to update. The vtable 3456 // holds the Method*s for virtual (but not final) methods. 3457 // Default methods, or concrete methods in interfaces are stored 3458 // in the vtable, so if an interface changes we need to check 3459 // adjust_method_entries() for every InstanceKlass, which will also 3460 // adjust the default method vtable indices. 3461 // We also need to adjust any default method entries that are 3462 // not yet in the vtable, because the vtable setup is in progress. 3463 // This must be done after we adjust the default_methods and 3464 // default_vtable_indices for methods already in the vtable. 3465 // If redefining Unsafe, walk all the vtables looking for entries. 3466 if (ik->vtable_length() > 0 && (_the_class->is_interface() 3467 || _the_class == SystemDictionary::internal_Unsafe_klass() 3468 || ik->is_subtype_of(_the_class))) { 3469 // ik->vtable() creates a wrapper object; rm cleans it up 3470 ResourceMark rm(_thread); 3471 3472 ik->vtable().adjust_method_entries(the_class, &trace_name_printed); 3473 ik->adjust_default_methods(the_class, &trace_name_printed); 3474 } 3475 3476 // If the current class has an itable and we are either redefining an 3477 // interface or if the current class is a subclass of the_class, then 3478 // we potentially have to fix the itable. If we are redefining an 3479 // interface, then we have to call adjust_method_entries() for 3480 // every InstanceKlass that has an itable since there isn't a 3481 // subclass relationship between an interface and an InstanceKlass. 3482 // If redefining Unsafe, walk all the itables looking for entries. 3483 if (ik->itable_length() > 0 && (_the_class->is_interface() 3484 || _the_class == SystemDictionary::internal_Unsafe_klass() 3485 || ik->is_subclass_of(_the_class))) { 3486 ResourceMark rm(_thread); 3487 ik->itable().adjust_method_entries(the_class, &trace_name_printed); 3488 } 3489 3490 // The constant pools in other classes (other_cp) can refer to 3491 // methods in the_class. We have to update method information in 3492 // other_cp's cache. If other_cp has a previous version, then we 3493 // have to repeat the process for each previous version. The 3494 // constant pool cache holds the Method*s for non-virtual 3495 // methods and for virtual, final methods. 3496 // 3497 // Special case: if the current class is the_class, then new_cp 3498 // has already been attached to the_class and old_cp has already 3499 // been added as a previous version. The new_cp doesn't have any 3500 // cached references to old methods so it doesn't need to be 3501 // updated. We can simply start with the previous version(s) in 3502 // that case. 3503 constantPoolHandle other_cp; 3504 ConstantPoolCache* cp_cache; 3505 3506 if (ik != _the_class) { 3507 // this klass' constant pool cache may need adjustment 3508 other_cp = constantPoolHandle(ik->constants()); 3509 cp_cache = other_cp->cache(); 3510 if (cp_cache != NULL) { 3511 cp_cache->adjust_method_entries(the_class, &trace_name_printed); 3512 } 3513 } 3514 3515 // the previous versions' constant pool caches may need adjustment 3516 for (InstanceKlass* pv_node = ik->previous_versions(); 3517 pv_node != NULL; 3518 pv_node = pv_node->previous_versions()) { 3519 cp_cache = pv_node->constants()->cache(); 3520 if (cp_cache != NULL) { 3521 cp_cache->adjust_method_entries(pv_node, &trace_name_printed); 3522 } 3523 } 3524 } 3525 } 3526 3527 // Clean method data for this class 3528 void VM_RedefineClasses::MethodDataCleaner::do_klass(Klass* k) { 3529 if (k->is_instance_klass()) { 3530 InstanceKlass *ik = InstanceKlass::cast(k); 3531 // Clean MethodData of this class's methods so they don't refer to 3532 // old methods that are no longer running. 3533 Array<Method*>* methods = ik->methods(); 3534 int num_methods = methods->length(); 3535 for (int index = 0; index < num_methods; ++index) { 3536 if (methods->at(index)->method_data() != NULL) { 3537 methods->at(index)->method_data()->clean_weak_method_links(); 3538 } 3539 } 3540 } 3541 } 3542 3543 void VM_RedefineClasses::update_jmethod_ids() { 3544 for (int j = 0; j < _matching_methods_length; ++j) { 3545 Method* old_method = _matching_old_methods[j]; 3546 jmethodID jmid = old_method->find_jmethod_id_or_null(); 3547 if (jmid != NULL) { 3548 // There is a jmethodID, change it to point to the new method 3549 methodHandle new_method_h(_matching_new_methods[j]); 3550 Method::change_method_associated_with_jmethod_id(jmid, new_method_h()); 3551 assert(Method::resolve_jmethod_id(jmid) == _matching_new_methods[j], 3552 "should be replaced"); 3553 } 3554 } 3555 } 3556 3557 int VM_RedefineClasses::check_methods_and_mark_as_obsolete() { 3558 int emcp_method_count = 0; 3559 int obsolete_count = 0; 3560 int old_index = 0; 3561 for (int j = 0; j < _matching_methods_length; ++j, ++old_index) { 3562 Method* old_method = _matching_old_methods[j]; 3563 Method* new_method = _matching_new_methods[j]; 3564 Method* old_array_method; 3565 3566 // Maintain an old_index into the _old_methods array by skipping 3567 // deleted methods 3568 while ((old_array_method = _old_methods->at(old_index)) != old_method) { 3569 ++old_index; 3570 } 3571 3572 if (MethodComparator::methods_EMCP(old_method, new_method)) { 3573 // The EMCP definition from JSR-163 requires the bytecodes to be 3574 // the same with the exception of constant pool indices which may 3575 // differ. However, the constants referred to by those indices 3576 // must be the same. 3577 // 3578 // We use methods_EMCP() for comparison since constant pool 3579 // merging can remove duplicate constant pool entries that were 3580 // present in the old method and removed from the rewritten new 3581 // method. A faster binary comparison function would consider the 3582 // old and new methods to be different when they are actually 3583 // EMCP. 3584 // 3585 // The old and new methods are EMCP and you would think that we 3586 // could get rid of one of them here and now and save some space. 3587 // However, the concept of EMCP only considers the bytecodes and 3588 // the constant pool entries in the comparison. Other things, 3589 // e.g., the line number table (LNT) or the local variable table 3590 // (LVT) don't count in the comparison. So the new (and EMCP) 3591 // method can have a new LNT that we need so we can't just 3592 // overwrite the new method with the old method. 3593 // 3594 // When this routine is called, we have already attached the new 3595 // methods to the_class so the old methods are effectively 3596 // overwritten. However, if an old method is still executing, 3597 // then the old method cannot be collected until sometime after 3598 // the old method call has returned. So the overwriting of old 3599 // methods by new methods will save us space except for those 3600 // (hopefully few) old methods that are still executing. 3601 // 3602 // A method refers to a ConstMethod* and this presents another 3603 // possible avenue to space savings. The ConstMethod* in the 3604 // new method contains possibly new attributes (LNT, LVT, etc). 3605 // At first glance, it seems possible to save space by replacing 3606 // the ConstMethod* in the old method with the ConstMethod* 3607 // from the new method. The old and new methods would share the 3608 // same ConstMethod* and we would save the space occupied by 3609 // the old ConstMethod*. However, the ConstMethod* contains 3610 // a back reference to the containing method. Sharing the 3611 // ConstMethod* between two methods could lead to confusion in 3612 // the code that uses the back reference. This would lead to 3613 // brittle code that could be broken in non-obvious ways now or 3614 // in the future. 3615 // 3616 // Another possibility is to copy the ConstMethod* from the new 3617 // method to the old method and then overwrite the new method with 3618 // the old method. Since the ConstMethod* contains the bytecodes 3619 // for the method embedded in the oop, this option would change 3620 // the bytecodes out from under any threads executing the old 3621 // method and make the thread's bcp invalid. Since EMCP requires 3622 // that the bytecodes be the same modulo constant pool indices, it 3623 // is straight forward to compute the correct new bcp in the new 3624 // ConstMethod* from the old bcp in the old ConstMethod*. The 3625 // time consuming part would be searching all the frames in all 3626 // of the threads to find all of the calls to the old method. 3627 // 3628 // It looks like we will have to live with the limited savings 3629 // that we get from effectively overwriting the old methods 3630 // when the new methods are attached to the_class. 3631 3632 // Count number of methods that are EMCP. The method will be marked 3633 // old but not obsolete if it is EMCP. 3634 emcp_method_count++; 3635 3636 // An EMCP method is _not_ obsolete. An obsolete method has a 3637 // different jmethodID than the current method. An EMCP method 3638 // has the same jmethodID as the current method. Having the 3639 // same jmethodID for all EMCP versions of a method allows for 3640 // a consistent view of the EMCP methods regardless of which 3641 // EMCP method you happen to have in hand. For example, a 3642 // breakpoint set in one EMCP method will work for all EMCP 3643 // versions of the method including the current one. 3644 } else { 3645 // mark obsolete methods as such 3646 old_method->set_is_obsolete(); 3647 obsolete_count++; 3648 3649 // obsolete methods need a unique idnum so they become new entries in 3650 // the jmethodID cache in InstanceKlass 3651 assert(old_method->method_idnum() == new_method->method_idnum(), "must match"); 3652 u2 num = InstanceKlass::cast(_the_class)->next_method_idnum(); 3653 if (num != ConstMethod::UNSET_IDNUM) { 3654 old_method->set_method_idnum(num); 3655 } 3656 3657 // With tracing we try not to "yack" too much. The position of 3658 // this trace assumes there are fewer obsolete methods than 3659 // EMCP methods. 3660 if (log_is_enabled(Trace, redefine, class, obsolete, mark)) { 3661 ResourceMark rm; 3662 log_trace(redefine, class, obsolete, mark) 3663 ("mark %s(%s) as obsolete", old_method->name()->as_C_string(), old_method->signature()->as_C_string()); 3664 } 3665 } 3666 old_method->set_is_old(); 3667 } 3668 for (int i = 0; i < _deleted_methods_length; ++i) { 3669 Method* old_method = _deleted_methods[i]; 3670 3671 assert(!old_method->has_vtable_index(), 3672 "cannot delete methods with vtable entries");; 3673 3674 // Mark all deleted methods as old, obsolete and deleted 3675 old_method->set_is_deleted(); 3676 old_method->set_is_old(); 3677 old_method->set_is_obsolete(); 3678 ++obsolete_count; 3679 // With tracing we try not to "yack" too much. The position of 3680 // this trace assumes there are fewer obsolete methods than 3681 // EMCP methods. 3682 if (log_is_enabled(Trace, redefine, class, obsolete, mark)) { 3683 ResourceMark rm; 3684 log_trace(redefine, class, obsolete, mark) 3685 ("mark deleted %s(%s) as obsolete", old_method->name()->as_C_string(), old_method->signature()->as_C_string()); 3686 } 3687 } 3688 assert((emcp_method_count + obsolete_count) == _old_methods->length(), 3689 "sanity check"); 3690 log_trace(redefine, class, obsolete, mark)("EMCP_cnt=%d, obsolete_cnt=%d", emcp_method_count, obsolete_count); 3691 return emcp_method_count; 3692 } 3693 3694 // This internal class transfers the native function registration from old methods 3695 // to new methods. It is designed to handle both the simple case of unchanged 3696 // native methods and the complex cases of native method prefixes being added and/or 3697 // removed. 3698 // It expects only to be used during the VM_RedefineClasses op (a safepoint). 3699 // 3700 // This class is used after the new methods have been installed in "the_class". 3701 // 3702 // So, for example, the following must be handled. Where 'm' is a method and 3703 // a number followed by an underscore is a prefix. 3704 // 3705 // Old Name New Name 3706 // Simple transfer to new method m -> m 3707 // Add prefix m -> 1_m 3708 // Remove prefix 1_m -> m 3709 // Simultaneous add of prefixes m -> 3_2_1_m 3710 // Simultaneous removal of prefixes 3_2_1_m -> m 3711 // Simultaneous add and remove 1_m -> 2_m 3712 // Same, caused by prefix removal only 3_2_1_m -> 3_2_m 3713 // 3714 class TransferNativeFunctionRegistration { 3715 private: 3716 InstanceKlass* the_class; 3717 int prefix_count; 3718 char** prefixes; 3719 3720 // Recursively search the binary tree of possibly prefixed method names. 3721 // Iteration could be used if all agents were well behaved. Full tree walk is 3722 // more resilent to agents not cleaning up intermediate methods. 3723 // Branch at each depth in the binary tree is: 3724 // (1) without the prefix. 3725 // (2) with the prefix. 3726 // where 'prefix' is the prefix at that 'depth' (first prefix, second prefix,...) 3727 Method* search_prefix_name_space(int depth, char* name_str, size_t name_len, 3728 Symbol* signature) { 3729 TempNewSymbol name_symbol = SymbolTable::probe(name_str, (int)name_len); 3730 if (name_symbol != NULL) { 3731 Method* method = the_class->lookup_method(name_symbol, signature); 3732 if (method != NULL) { 3733 // Even if prefixed, intermediate methods must exist. 3734 if (method->is_native()) { 3735 // Wahoo, we found a (possibly prefixed) version of the method, return it. 3736 return method; 3737 } 3738 if (depth < prefix_count) { 3739 // Try applying further prefixes (other than this one). 3740 method = search_prefix_name_space(depth+1, name_str, name_len, signature); 3741 if (method != NULL) { 3742 return method; // found 3743 } 3744 3745 // Try adding this prefix to the method name and see if it matches 3746 // another method name. 3747 char* prefix = prefixes[depth]; 3748 size_t prefix_len = strlen(prefix); 3749 size_t trial_len = name_len + prefix_len; 3750 char* trial_name_str = NEW_RESOURCE_ARRAY(char, trial_len + 1); 3751 strcpy(trial_name_str, prefix); 3752 strcat(trial_name_str, name_str); 3753 method = search_prefix_name_space(depth+1, trial_name_str, trial_len, 3754 signature); 3755 if (method != NULL) { 3756 // If found along this branch, it was prefixed, mark as such 3757 method->set_is_prefixed_native(); 3758 return method; // found 3759 } 3760 } 3761 } 3762 } 3763 return NULL; // This whole branch bore nothing 3764 } 3765 3766 // Return the method name with old prefixes stripped away. 3767 char* method_name_without_prefixes(Method* method) { 3768 Symbol* name = method->name(); 3769 char* name_str = name->as_utf8(); 3770 3771 // Old prefixing may be defunct, strip prefixes, if any. 3772 for (int i = prefix_count-1; i >= 0; i--) { 3773 char* prefix = prefixes[i]; 3774 size_t prefix_len = strlen(prefix); 3775 if (strncmp(prefix, name_str, prefix_len) == 0) { 3776 name_str += prefix_len; 3777 } 3778 } 3779 return name_str; 3780 } 3781 3782 // Strip any prefixes off the old native method, then try to find a 3783 // (possibly prefixed) new native that matches it. 3784 Method* strip_and_search_for_new_native(Method* method) { 3785 ResourceMark rm; 3786 char* name_str = method_name_without_prefixes(method); 3787 return search_prefix_name_space(0, name_str, strlen(name_str), 3788 method->signature()); 3789 } 3790 3791 public: 3792 3793 // Construct a native method transfer processor for this class. 3794 TransferNativeFunctionRegistration(InstanceKlass* _the_class) { 3795 assert(SafepointSynchronize::is_at_safepoint(), "sanity check"); 3796 3797 the_class = _the_class; 3798 prefixes = JvmtiExport::get_all_native_method_prefixes(&prefix_count); 3799 } 3800 3801 // Attempt to transfer any of the old or deleted methods that are native 3802 void transfer_registrations(Method** old_methods, int methods_length) { 3803 for (int j = 0; j < methods_length; j++) { 3804 Method* old_method = old_methods[j]; 3805 3806 if (old_method->is_native() && old_method->has_native_function()) { 3807 Method* new_method = strip_and_search_for_new_native(old_method); 3808 if (new_method != NULL) { 3809 // Actually set the native function in the new method. 3810 // Redefine does not send events (except CFLH), certainly not this 3811 // behind the scenes re-registration. 3812 new_method->set_native_function(old_method->native_function(), 3813 !Method::native_bind_event_is_interesting); 3814 } 3815 } 3816 } 3817 } 3818 }; 3819 3820 // Don't lose the association between a native method and its JNI function. 3821 void VM_RedefineClasses::transfer_old_native_function_registrations(InstanceKlass* the_class) { 3822 TransferNativeFunctionRegistration transfer(the_class); 3823 transfer.transfer_registrations(_deleted_methods, _deleted_methods_length); 3824 transfer.transfer_registrations(_matching_old_methods, _matching_methods_length); 3825 } 3826 3827 // Deoptimize all compiled code that depends on this class. 3828 // 3829 // If the can_redefine_classes capability is obtained in the onload 3830 // phase then the compiler has recorded all dependencies from startup. 3831 // In that case we need only deoptimize and throw away all compiled code 3832 // that depends on the class. 3833 // 3834 // If can_redefine_classes is obtained sometime after the onload 3835 // phase then the dependency information may be incomplete. In that case 3836 // the first call to RedefineClasses causes all compiled code to be 3837 // thrown away. As can_redefine_classes has been obtained then 3838 // all future compilations will record dependencies so second and 3839 // subsequent calls to RedefineClasses need only throw away code 3840 // that depends on the class. 3841 // 3842 void VM_RedefineClasses::flush_dependent_code(InstanceKlass* ik, TRAPS) { 3843 assert_locked_or_safepoint(Compile_lock); 3844 3845 // All dependencies have been recorded from startup or this is a second or 3846 // subsequent use of RedefineClasses 3847 if (JvmtiExport::all_dependencies_are_recorded()) { 3848 CodeCache::flush_evol_dependents_on(ik); 3849 } else { 3850 CodeCache::mark_all_nmethods_for_deoptimization(); 3851 3852 ResourceMark rm(THREAD); 3853 DeoptimizationMarker dm; 3854 3855 // Deoptimize all activations depending on marked nmethods 3856 Deoptimization::deoptimize_dependents(); 3857 3858 // Make the dependent methods not entrant 3859 CodeCache::make_marked_nmethods_not_entrant(); 3860 3861 // From now on we know that the dependency information is complete 3862 JvmtiExport::set_all_dependencies_are_recorded(true); 3863 } 3864 } 3865 3866 void VM_RedefineClasses::compute_added_deleted_matching_methods() { 3867 Method* old_method; 3868 Method* new_method; 3869 3870 _matching_old_methods = NEW_RESOURCE_ARRAY(Method*, _old_methods->length()); 3871 _matching_new_methods = NEW_RESOURCE_ARRAY(Method*, _old_methods->length()); 3872 _added_methods = NEW_RESOURCE_ARRAY(Method*, _new_methods->length()); 3873 _deleted_methods = NEW_RESOURCE_ARRAY(Method*, _old_methods->length()); 3874 3875 _matching_methods_length = 0; 3876 _deleted_methods_length = 0; 3877 _added_methods_length = 0; 3878 3879 int nj = 0; 3880 int oj = 0; 3881 while (true) { 3882 if (oj >= _old_methods->length()) { 3883 if (nj >= _new_methods->length()) { 3884 break; // we've looked at everything, done 3885 } 3886 // New method at the end 3887 new_method = _new_methods->at(nj); 3888 _added_methods[_added_methods_length++] = new_method; 3889 ++nj; 3890 } else if (nj >= _new_methods->length()) { 3891 // Old method, at the end, is deleted 3892 old_method = _old_methods->at(oj); 3893 _deleted_methods[_deleted_methods_length++] = old_method; 3894 ++oj; 3895 } else { 3896 old_method = _old_methods->at(oj); 3897 new_method = _new_methods->at(nj); 3898 if (old_method->name() == new_method->name()) { 3899 if (old_method->signature() == new_method->signature()) { 3900 _matching_old_methods[_matching_methods_length ] = old_method; 3901 _matching_new_methods[_matching_methods_length++] = new_method; 3902 ++nj; 3903 ++oj; 3904 } else { 3905 // added overloaded have already been moved to the end, 3906 // so this is a deleted overloaded method 3907 _deleted_methods[_deleted_methods_length++] = old_method; 3908 ++oj; 3909 } 3910 } else { // names don't match 3911 if (old_method->name()->fast_compare(new_method->name()) > 0) { 3912 // new method 3913 _added_methods[_added_methods_length++] = new_method; 3914 ++nj; 3915 } else { 3916 // deleted method 3917 _deleted_methods[_deleted_methods_length++] = old_method; 3918 ++oj; 3919 } 3920 } 3921 } 3922 } 3923 assert(_matching_methods_length + _deleted_methods_length == _old_methods->length(), "sanity"); 3924 assert(_matching_methods_length + _added_methods_length == _new_methods->length(), "sanity"); 3925 } 3926 3927 3928 void VM_RedefineClasses::swap_annotations(InstanceKlass* the_class, 3929 InstanceKlass* scratch_class) { 3930 // Swap annotation fields values 3931 Annotations* old_annotations = the_class->annotations(); 3932 the_class->set_annotations(scratch_class->annotations()); 3933 scratch_class->set_annotations(old_annotations); 3934 } 3935 3936 3937 // Install the redefinition of a class: 3938 // - house keeping (flushing breakpoints and caches, deoptimizing 3939 // dependent compiled code) 3940 // - replacing parts in the_class with parts from scratch_class 3941 // - adding a weak reference to track the obsolete but interesting 3942 // parts of the_class 3943 // - adjusting constant pool caches and vtables in other classes 3944 // that refer to methods in the_class. These adjustments use the 3945 // ClassLoaderDataGraph::classes_do() facility which only allows 3946 // a helper method to be specified. The interesting parameters 3947 // that we would like to pass to the helper method are saved in 3948 // static global fields in the VM operation. 3949 void VM_RedefineClasses::redefine_single_class(jclass the_jclass, 3950 InstanceKlass* scratch_class, TRAPS) { 3951 3952 HandleMark hm(THREAD); // make sure handles from this call are freed 3953 3954 if (log_is_enabled(Info, redefine, class, timer)) { 3955 _timer_rsc_phase1.start(); 3956 } 3957 3958 InstanceKlass* the_class = get_ik(the_jclass); 3959 3960 // Remove all breakpoints in methods of this class 3961 JvmtiBreakpoints& jvmti_breakpoints = JvmtiCurrentBreakpoints::get_jvmti_breakpoints(); 3962 jvmti_breakpoints.clearall_in_class_at_safepoint(the_class); 3963 3964 // Deoptimize all compiled code that depends on this class 3965 flush_dependent_code(the_class, THREAD); 3966 3967 _old_methods = the_class->methods(); 3968 _new_methods = scratch_class->methods(); 3969 _the_class = the_class; 3970 compute_added_deleted_matching_methods(); 3971 update_jmethod_ids(); 3972 3973 _any_class_has_resolved_methods = the_class->has_resolved_methods() || _any_class_has_resolved_methods; 3974 3975 // Attach new constant pool to the original klass. The original 3976 // klass still refers to the old constant pool (for now). 3977 scratch_class->constants()->set_pool_holder(the_class); 3978 3979 #if 0 3980 // In theory, with constant pool merging in place we should be able 3981 // to save space by using the new, merged constant pool in place of 3982 // the old constant pool(s). By "pool(s)" I mean the constant pool in 3983 // the klass version we are replacing now and any constant pool(s) in 3984 // previous versions of klass. Nice theory, doesn't work in practice. 3985 // When this code is enabled, even simple programs throw NullPointer 3986 // exceptions. I'm guessing that this is caused by some constant pool 3987 // cache difference between the new, merged constant pool and the 3988 // constant pool that was just being used by the klass. I'm keeping 3989 // this code around to archive the idea, but the code has to remain 3990 // disabled for now. 3991 3992 // Attach each old method to the new constant pool. This can be 3993 // done here since we are past the bytecode verification and 3994 // constant pool optimization phases. 3995 for (int i = _old_methods->length() - 1; i >= 0; i--) { 3996 Method* method = _old_methods->at(i); 3997 method->set_constants(scratch_class->constants()); 3998 } 3999 4000 // NOTE: this doesn't work because you can redefine the same class in two 4001 // threads, each getting their own constant pool data appended to the 4002 // original constant pool. In order for the new methods to work when they 4003 // become old methods, they need to keep their updated copy of the constant pool. 4004 4005 { 4006 // walk all previous versions of the klass 4007 InstanceKlass *ik = the_class; 4008 PreviousVersionWalker pvw(ik); 4009 do { 4010 ik = pvw.next_previous_version(); 4011 if (ik != NULL) { 4012 4013 // attach previous version of klass to the new constant pool 4014 ik->set_constants(scratch_class->constants()); 4015 4016 // Attach each method in the previous version of klass to the 4017 // new constant pool 4018 Array<Method*>* prev_methods = ik->methods(); 4019 for (int i = prev_methods->length() - 1; i >= 0; i--) { 4020 Method* method = prev_methods->at(i); 4021 method->set_constants(scratch_class->constants()); 4022 } 4023 } 4024 } while (ik != NULL); 4025 } 4026 #endif 4027 4028 // Replace methods and constantpool 4029 the_class->set_methods(_new_methods); 4030 scratch_class->set_methods(_old_methods); // To prevent potential GCing of the old methods, 4031 // and to be able to undo operation easily. 4032 4033 Array<int>* old_ordering = the_class->method_ordering(); 4034 the_class->set_method_ordering(scratch_class->method_ordering()); 4035 scratch_class->set_method_ordering(old_ordering); 4036 4037 ConstantPool* old_constants = the_class->constants(); 4038 the_class->set_constants(scratch_class->constants()); 4039 scratch_class->set_constants(old_constants); // See the previous comment. 4040 #if 0 4041 // We are swapping the guts of "the new class" with the guts of "the 4042 // class". Since the old constant pool has just been attached to "the 4043 // new class", it seems logical to set the pool holder in the old 4044 // constant pool also. However, doing this will change the observable 4045 // class hierarchy for any old methods that are still executing. A 4046 // method can query the identity of its "holder" and this query uses 4047 // the method's constant pool link to find the holder. The change in 4048 // holding class from "the class" to "the new class" can confuse 4049 // things. 4050 // 4051 // Setting the old constant pool's holder will also cause 4052 // verification done during vtable initialization below to fail. 4053 // During vtable initialization, the vtable's class is verified to be 4054 // a subtype of the method's holder. The vtable's class is "the 4055 // class" and the method's holder is gotten from the constant pool 4056 // link in the method itself. For "the class"'s directly implemented 4057 // methods, the method holder is "the class" itself (as gotten from 4058 // the new constant pool). The check works fine in this case. The 4059 // check also works fine for methods inherited from super classes. 4060 // 4061 // Miranda methods are a little more complicated. A miranda method is 4062 // provided by an interface when the class implementing the interface 4063 // does not provide its own method. These interfaces are implemented 4064 // internally as an InstanceKlass. These special instanceKlasses 4065 // share the constant pool of the class that "implements" the 4066 // interface. By sharing the constant pool, the method holder of a 4067 // miranda method is the class that "implements" the interface. In a 4068 // non-redefine situation, the subtype check works fine. However, if 4069 // the old constant pool's pool holder is modified, then the check 4070 // fails because there is no class hierarchy relationship between the 4071 // vtable's class and "the new class". 4072 4073 old_constants->set_pool_holder(scratch_class()); 4074 #endif 4075 4076 // track number of methods that are EMCP for add_previous_version() call below 4077 int emcp_method_count = check_methods_and_mark_as_obsolete(); 4078 transfer_old_native_function_registrations(the_class); 4079 4080 // The class file bytes from before any retransformable agents mucked 4081 // with them was cached on the scratch class, move to the_class. 4082 // Note: we still want to do this if nothing needed caching since it 4083 // should get cleared in the_class too. 4084 if (the_class->get_cached_class_file() == 0) { 4085 // the_class doesn't have a cache yet so copy it 4086 the_class->set_cached_class_file(scratch_class->get_cached_class_file()); 4087 } 4088 else if (scratch_class->get_cached_class_file() != 4089 the_class->get_cached_class_file()) { 4090 // The same class can be present twice in the scratch classes list or there 4091 // are multiple concurrent RetransformClasses calls on different threads. 4092 // In such cases we have to deallocate scratch_class cached_class_file. 4093 os::free(scratch_class->get_cached_class_file()); 4094 } 4095 4096 // NULL out in scratch class to not delete twice. The class to be redefined 4097 // always owns these bytes. 4098 scratch_class->set_cached_class_file(NULL); 4099 4100 // Replace inner_classes 4101 Array<u2>* old_inner_classes = the_class->inner_classes(); 4102 the_class->set_inner_classes(scratch_class->inner_classes()); 4103 scratch_class->set_inner_classes(old_inner_classes); 4104 4105 // Initialize the vtable and interface table after 4106 // methods have been rewritten 4107 { 4108 ResourceMark rm(THREAD); 4109 // no exception should happen here since we explicitly 4110 // do not check loader constraints. 4111 // compare_and_normalize_class_versions has already checked: 4112 // - classloaders unchanged, signatures unchanged 4113 // - all instanceKlasses for redefined classes reused & contents updated 4114 the_class->vtable().initialize_vtable(false, THREAD); 4115 the_class->itable().initialize_itable(false, THREAD); 4116 assert(!HAS_PENDING_EXCEPTION || (THREAD->pending_exception()->is_a(SystemDictionary::ThreadDeath_klass())), "redefine exception"); 4117 } 4118 4119 // Leave arrays of jmethodIDs and itable index cache unchanged 4120 4121 // Copy the "source file name" attribute from new class version 4122 the_class->set_source_file_name_index( 4123 scratch_class->source_file_name_index()); 4124 4125 // Copy the "source debug extension" attribute from new class version 4126 the_class->set_source_debug_extension( 4127 scratch_class->source_debug_extension(), 4128 scratch_class->source_debug_extension() == NULL ? 0 : 4129 (int)strlen(scratch_class->source_debug_extension())); 4130 4131 // Use of javac -g could be different in the old and the new 4132 if (scratch_class->access_flags().has_localvariable_table() != 4133 the_class->access_flags().has_localvariable_table()) { 4134 4135 AccessFlags flags = the_class->access_flags(); 4136 if (scratch_class->access_flags().has_localvariable_table()) { 4137 flags.set_has_localvariable_table(); 4138 } else { 4139 flags.clear_has_localvariable_table(); 4140 } 4141 the_class->set_access_flags(flags); 4142 } 4143 4144 swap_annotations(the_class, scratch_class); 4145 4146 // Replace minor version number of class file 4147 u2 old_minor_version = the_class->minor_version(); 4148 the_class->set_minor_version(scratch_class->minor_version()); 4149 scratch_class->set_minor_version(old_minor_version); 4150 4151 // Replace major version number of class file 4152 u2 old_major_version = the_class->major_version(); 4153 the_class->set_major_version(scratch_class->major_version()); 4154 scratch_class->set_major_version(old_major_version); 4155 4156 // Replace CP indexes for class and name+type of enclosing method 4157 u2 old_class_idx = the_class->enclosing_method_class_index(); 4158 u2 old_method_idx = the_class->enclosing_method_method_index(); 4159 the_class->set_enclosing_method_indices( 4160 scratch_class->enclosing_method_class_index(), 4161 scratch_class->enclosing_method_method_index()); 4162 scratch_class->set_enclosing_method_indices(old_class_idx, old_method_idx); 4163 4164 // Replace fingerprint data 4165 the_class->set_has_passed_fingerprint_check(scratch_class->has_passed_fingerprint_check()); 4166 the_class->store_fingerprint(scratch_class->get_stored_fingerprint()); 4167 4168 the_class->set_has_been_redefined(); 4169 4170 if (!the_class->should_be_initialized()) { 4171 // Class was already initialized, so AOT has only seen the original version. 4172 // We need to let AOT look at it again. 4173 AOTLoader::load_for_klass(the_class, THREAD); 4174 } 4175 4176 // keep track of previous versions of this class 4177 the_class->add_previous_version(scratch_class, emcp_method_count); 4178 4179 _timer_rsc_phase1.stop(); 4180 if (log_is_enabled(Info, redefine, class, timer)) { 4181 _timer_rsc_phase2.start(); 4182 } 4183 4184 // Adjust constantpool caches and vtables for all classes 4185 // that reference methods of the evolved class. 4186 AdjustCpoolCacheAndVtable adjust_cpool_cache_and_vtable(THREAD); 4187 ClassLoaderDataGraph::classes_do(&adjust_cpool_cache_and_vtable); 4188 4189 if (the_class->oop_map_cache() != NULL) { 4190 // Flush references to any obsolete methods from the oop map cache 4191 // so that obsolete methods are not pinned. 4192 the_class->oop_map_cache()->flush_obsolete_entries(); 4193 } 4194 4195 increment_class_counter((InstanceKlass *)the_class, THREAD); 4196 { 4197 ResourceMark rm(THREAD); 4198 // increment the classRedefinedCount field in the_class and in any 4199 // direct and indirect subclasses of the_class 4200 log_info(redefine, class, load) 4201 ("redefined name=%s, count=%d (avail_mem=" UINT64_FORMAT "K)", 4202 the_class->external_name(), java_lang_Class::classRedefinedCount(the_class->java_mirror()), os::available_memory() >> 10); 4203 Events::log_redefinition(THREAD, "redefined class name=%s, count=%d", 4204 the_class->external_name(), 4205 java_lang_Class::classRedefinedCount(the_class->java_mirror())); 4206 4207 } 4208 _timer_rsc_phase2.stop(); 4209 } // end redefine_single_class() 4210 4211 4212 // Increment the classRedefinedCount field in the specific InstanceKlass 4213 // and in all direct and indirect subclasses. 4214 void VM_RedefineClasses::increment_class_counter(InstanceKlass *ik, TRAPS) { 4215 oop class_mirror = ik->java_mirror(); 4216 Klass* class_oop = java_lang_Class::as_Klass(class_mirror); 4217 int new_count = java_lang_Class::classRedefinedCount(class_mirror) + 1; 4218 java_lang_Class::set_classRedefinedCount(class_mirror, new_count); 4219 4220 if (class_oop != _the_class) { 4221 // _the_class count is printed at end of redefine_single_class() 4222 log_debug(redefine, class, subclass)("updated count in subclass=%s to %d", ik->external_name(), new_count); 4223 } 4224 4225 for (Klass *subk = ik->subklass(); subk != NULL; 4226 subk = subk->next_sibling()) { 4227 if (subk->is_instance_klass()) { 4228 // Only update instanceKlasses 4229 InstanceKlass *subik = InstanceKlass::cast(subk); 4230 // recursively do subclasses of the current subclass 4231 increment_class_counter(subik, THREAD); 4232 } 4233 } 4234 } 4235 4236 void VM_RedefineClasses::CheckClass::do_klass(Klass* k) { 4237 bool no_old_methods = true; // be optimistic 4238 4239 // Both array and instance classes have vtables. 4240 // a vtable should never contain old or obsolete methods 4241 ResourceMark rm(_thread); 4242 if (k->vtable_length() > 0 && 4243 !k->vtable().check_no_old_or_obsolete_entries()) { 4244 if (log_is_enabled(Trace, redefine, class, obsolete, metadata)) { 4245 log_trace(redefine, class, obsolete, metadata) 4246 ("klassVtable::check_no_old_or_obsolete_entries failure -- OLD or OBSOLETE method found -- class: %s", 4247 k->signature_name()); 4248 k->vtable().dump_vtable(); 4249 } 4250 no_old_methods = false; 4251 } 4252 4253 if (k->is_instance_klass()) { 4254 HandleMark hm(_thread); 4255 InstanceKlass *ik = InstanceKlass::cast(k); 4256 4257 // an itable should never contain old or obsolete methods 4258 if (ik->itable_length() > 0 && 4259 !ik->itable().check_no_old_or_obsolete_entries()) { 4260 if (log_is_enabled(Trace, redefine, class, obsolete, metadata)) { 4261 log_trace(redefine, class, obsolete, metadata) 4262 ("klassItable::check_no_old_or_obsolete_entries failure -- OLD or OBSOLETE method found -- class: %s", 4263 ik->signature_name()); 4264 ik->itable().dump_itable(); 4265 } 4266 no_old_methods = false; 4267 } 4268 4269 // the constant pool cache should never contain non-deleted old or obsolete methods 4270 if (ik->constants() != NULL && 4271 ik->constants()->cache() != NULL && 4272 !ik->constants()->cache()->check_no_old_or_obsolete_entries()) { 4273 if (log_is_enabled(Trace, redefine, class, obsolete, metadata)) { 4274 log_trace(redefine, class, obsolete, metadata) 4275 ("cp-cache::check_no_old_or_obsolete_entries failure -- OLD or OBSOLETE method found -- class: %s", 4276 ik->signature_name()); 4277 ik->constants()->cache()->dump_cache(); 4278 } 4279 no_old_methods = false; 4280 } 4281 } 4282 4283 // print and fail guarantee if old methods are found. 4284 if (!no_old_methods) { 4285 if (log_is_enabled(Trace, redefine, class, obsolete, metadata)) { 4286 dump_methods(); 4287 } else { 4288 log_trace(redefine, class)("Use the '-Xlog:redefine+class*:' option " 4289 "to see more info about the following guarantee() failure."); 4290 } 4291 guarantee(false, "OLD and/or OBSOLETE method(s) found"); 4292 } 4293 } 4294 4295 4296 void VM_RedefineClasses::dump_methods() { 4297 int j; 4298 log_trace(redefine, class, dump)("_old_methods --"); 4299 for (j = 0; j < _old_methods->length(); ++j) { 4300 LogStreamHandle(Trace, redefine, class, dump) log_stream; 4301 Method* m = _old_methods->at(j); 4302 log_stream.print("%4d (%5d) ", j, m->vtable_index()); 4303 m->access_flags().print_on(&log_stream); 4304 log_stream.print(" -- "); 4305 m->print_name(&log_stream); 4306 log_stream.cr(); 4307 } 4308 log_trace(redefine, class, dump)("_new_methods --"); 4309 for (j = 0; j < _new_methods->length(); ++j) { 4310 LogStreamHandle(Trace, redefine, class, dump) log_stream; 4311 Method* m = _new_methods->at(j); 4312 log_stream.print("%4d (%5d) ", j, m->vtable_index()); 4313 m->access_flags().print_on(&log_stream); 4314 log_stream.print(" -- "); 4315 m->print_name(&log_stream); 4316 log_stream.cr(); 4317 } 4318 log_trace(redefine, class, dump)("_matching_methods --"); 4319 for (j = 0; j < _matching_methods_length; ++j) { 4320 LogStreamHandle(Trace, redefine, class, dump) log_stream; 4321 Method* m = _matching_old_methods[j]; 4322 log_stream.print("%4d (%5d) ", j, m->vtable_index()); 4323 m->access_flags().print_on(&log_stream); 4324 log_stream.print(" -- "); 4325 m->print_name(); 4326 log_stream.cr(); 4327 4328 m = _matching_new_methods[j]; 4329 log_stream.print(" (%5d) ", m->vtable_index()); 4330 m->access_flags().print_on(&log_stream); 4331 log_stream.cr(); 4332 } 4333 log_trace(redefine, class, dump)("_deleted_methods --"); 4334 for (j = 0; j < _deleted_methods_length; ++j) { 4335 LogStreamHandle(Trace, redefine, class, dump) log_stream; 4336 Method* m = _deleted_methods[j]; 4337 log_stream.print("%4d (%5d) ", j, m->vtable_index()); 4338 m->access_flags().print_on(&log_stream); 4339 log_stream.print(" -- "); 4340 m->print_name(&log_stream); 4341 log_stream.cr(); 4342 } 4343 log_trace(redefine, class, dump)("_added_methods --"); 4344 for (j = 0; j < _added_methods_length; ++j) { 4345 LogStreamHandle(Trace, redefine, class, dump) log_stream; 4346 Method* m = _added_methods[j]; 4347 log_stream.print("%4d (%5d) ", j, m->vtable_index()); 4348 m->access_flags().print_on(&log_stream); 4349 log_stream.print(" -- "); 4350 m->print_name(&log_stream); 4351 log_stream.cr(); 4352 } 4353 } 4354 4355 void VM_RedefineClasses::print_on_error(outputStream* st) const { 4356 VM_Operation::print_on_error(st); 4357 if (_the_class != NULL) { 4358 ResourceMark rm; 4359 st->print_cr(", redefining class %s", _the_class->external_name()); 4360 } 4361 }