1 /* 2 * Copyright (c) 2003, 2011, Oracle and/or its affiliates. All rights reserved. 3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. 4 * 5 * This code is free software; you can redistribute it and/or modify it 6 * under the terms of the GNU General Public License version 2 only, as 7 * published by the Free Software Foundation. 8 * 9 * This code is distributed in the hope that it will be useful, but WITHOUT 10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 12 * version 2 for more details (a copy is included in the LICENSE file that 13 * accompanied this code). 14 * 15 * You should have received a copy of the GNU General Public License version 16 * 2 along with this work; if not, write to the Free Software Foundation, 17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. 18 * 19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA 20 * or visit www.oracle.com if you need additional information or have any 21 * questions. 22 * 23 */ 24 25 #include "precompiled.hpp" 26 #include "classfile/systemDictionary.hpp" 27 #include "classfile/verifier.hpp" 28 #include "code/codeCache.hpp" 29 #include "interpreter/oopMapCache.hpp" 30 #include "interpreter/rewriter.hpp" 31 #include "memory/gcLocker.hpp" 32 #include "memory/universe.inline.hpp" 33 #include "oops/fieldStreams.hpp" 34 #include "oops/klassVtable.hpp" 35 #include "prims/jvmtiImpl.hpp" 36 #include "prims/jvmtiRedefineClasses.hpp" 37 #include "prims/methodComparator.hpp" 38 #include "runtime/deoptimization.hpp" 39 #include "runtime/relocator.hpp" 40 #include "utilities/bitMap.inline.hpp" 41 42 43 objArrayOop VM_RedefineClasses::_old_methods = NULL; 44 objArrayOop VM_RedefineClasses::_new_methods = NULL; 45 methodOop* VM_RedefineClasses::_matching_old_methods = NULL; 46 methodOop* VM_RedefineClasses::_matching_new_methods = NULL; 47 methodOop* VM_RedefineClasses::_deleted_methods = NULL; 48 methodOop* VM_RedefineClasses::_added_methods = NULL; 49 int VM_RedefineClasses::_matching_methods_length = 0; 50 int VM_RedefineClasses::_deleted_methods_length = 0; 51 int VM_RedefineClasses::_added_methods_length = 0; 52 klassOop VM_RedefineClasses::_the_class_oop = NULL; 53 54 55 VM_RedefineClasses::VM_RedefineClasses(jint class_count, 56 const jvmtiClassDefinition *class_defs, 57 JvmtiClassLoadKind class_load_kind) { 58 _class_count = class_count; 59 _class_defs = class_defs; 60 _class_load_kind = class_load_kind; 61 _res = JVMTI_ERROR_NONE; 62 } 63 64 bool VM_RedefineClasses::doit_prologue() { 65 if (_class_count == 0) { 66 _res = JVMTI_ERROR_NONE; 67 return false; 68 } 69 if (_class_defs == NULL) { 70 _res = JVMTI_ERROR_NULL_POINTER; 71 return false; 72 } 73 for (int i = 0; i < _class_count; i++) { 74 if (_class_defs[i].klass == NULL) { 75 _res = JVMTI_ERROR_INVALID_CLASS; 76 return false; 77 } 78 if (_class_defs[i].class_byte_count == 0) { 79 _res = JVMTI_ERROR_INVALID_CLASS_FORMAT; 80 return false; 81 } 82 if (_class_defs[i].class_bytes == NULL) { 83 _res = JVMTI_ERROR_NULL_POINTER; 84 return false; 85 } 86 } 87 88 // Start timer after all the sanity checks; not quite accurate, but 89 // better than adding a bunch of stop() calls. 90 RC_TIMER_START(_timer_vm_op_prologue); 91 92 // We first load new class versions in the prologue, because somewhere down the 93 // call chain it is required that the current thread is a Java thread. 94 _res = load_new_class_versions(Thread::current()); 95 if (_res != JVMTI_ERROR_NONE) { 96 // Free os::malloc allocated memory in load_new_class_version. 97 os::free(_scratch_classes); 98 RC_TIMER_STOP(_timer_vm_op_prologue); 99 return false; 100 } 101 102 RC_TIMER_STOP(_timer_vm_op_prologue); 103 return true; 104 } 105 106 void VM_RedefineClasses::doit() { 107 Thread *thread = Thread::current(); 108 109 if (UseSharedSpaces) { 110 // Sharing is enabled so we remap the shared readonly space to 111 // shared readwrite, private just in case we need to redefine 112 // a shared class. We do the remap during the doit() phase of 113 // the safepoint to be safer. 114 if (!CompactingPermGenGen::remap_shared_readonly_as_readwrite()) { 115 RC_TRACE_WITH_THREAD(0x00000001, thread, 116 ("failed to remap shared readonly space to readwrite, private")); 117 _res = JVMTI_ERROR_INTERNAL; 118 return; 119 } 120 } 121 122 for (int i = 0; i < _class_count; i++) { 123 redefine_single_class(_class_defs[i].klass, _scratch_classes[i], thread); 124 } 125 // Disable any dependent concurrent compilations 126 SystemDictionary::notice_modification(); 127 128 // Set flag indicating that some invariants are no longer true. 129 // See jvmtiExport.hpp for detailed explanation. 130 JvmtiExport::set_has_redefined_a_class(); 131 132 #ifdef ASSERT 133 SystemDictionary::classes_do(check_class, thread); 134 #endif 135 } 136 137 void VM_RedefineClasses::doit_epilogue() { 138 // Free os::malloc allocated memory. 139 // The memory allocated in redefine will be free'ed in next VM operation. 140 os::free(_scratch_classes); 141 142 if (RC_TRACE_ENABLED(0x00000004)) { 143 // Used to have separate timers for "doit" and "all", but the timer 144 // overhead skewed the measurements. 145 jlong doit_time = _timer_rsc_phase1.milliseconds() + 146 _timer_rsc_phase2.milliseconds(); 147 jlong all_time = _timer_vm_op_prologue.milliseconds() + doit_time; 148 149 RC_TRACE(0x00000004, ("vm_op: all=" UINT64_FORMAT 150 " prologue=" UINT64_FORMAT " doit=" UINT64_FORMAT, all_time, 151 _timer_vm_op_prologue.milliseconds(), doit_time)); 152 RC_TRACE(0x00000004, 153 ("redefine_single_class: phase1=" UINT64_FORMAT " phase2=" UINT64_FORMAT, 154 _timer_rsc_phase1.milliseconds(), _timer_rsc_phase2.milliseconds())); 155 } 156 } 157 158 bool VM_RedefineClasses::is_modifiable_class(oop klass_mirror) { 159 // classes for primitives cannot be redefined 160 if (java_lang_Class::is_primitive(klass_mirror)) { 161 return false; 162 } 163 klassOop the_class_oop = java_lang_Class::as_klassOop(klass_mirror); 164 // classes for arrays cannot be redefined 165 if (the_class_oop == NULL || !Klass::cast(the_class_oop)->oop_is_instance()) { 166 return false; 167 } 168 return true; 169 } 170 171 // Append the current entry at scratch_i in scratch_cp to *merge_cp_p 172 // where the end of *merge_cp_p is specified by *merge_cp_length_p. For 173 // direct CP entries, there is just the current entry to append. For 174 // indirect and double-indirect CP entries, there are zero or more 175 // referenced CP entries along with the current entry to append. 176 // Indirect and double-indirect CP entries are handled by recursive 177 // calls to append_entry() as needed. The referenced CP entries are 178 // always appended to *merge_cp_p before the referee CP entry. These 179 // referenced CP entries may already exist in *merge_cp_p in which case 180 // there is nothing extra to append and only the current entry is 181 // appended. 182 void VM_RedefineClasses::append_entry(constantPoolHandle scratch_cp, 183 int scratch_i, constantPoolHandle *merge_cp_p, int *merge_cp_length_p, 184 TRAPS) { 185 186 // append is different depending on entry tag type 187 switch (scratch_cp->tag_at(scratch_i).value()) { 188 189 // The old verifier is implemented outside the VM. It loads classes, 190 // but does not resolve constant pool entries directly so we never 191 // see Class entries here with the old verifier. Similarly the old 192 // verifier does not like Class entries in the input constant pool. 193 // The split-verifier is implemented in the VM so it can optionally 194 // and directly resolve constant pool entries to load classes. The 195 // split-verifier can accept either Class entries or UnresolvedClass 196 // entries in the input constant pool. We revert the appended copy 197 // back to UnresolvedClass so that either verifier will be happy 198 // with the constant pool entry. 199 case JVM_CONSTANT_Class: 200 { 201 // revert the copy to JVM_CONSTANT_UnresolvedClass 202 (*merge_cp_p)->unresolved_klass_at_put(*merge_cp_length_p, 203 scratch_cp->klass_name_at(scratch_i)); 204 205 if (scratch_i != *merge_cp_length_p) { 206 // The new entry in *merge_cp_p is at a different index than 207 // the new entry in scratch_cp so we need to map the index values. 208 map_index(scratch_cp, scratch_i, *merge_cp_length_p); 209 } 210 (*merge_cp_length_p)++; 211 } break; 212 213 // these are direct CP entries so they can be directly appended, 214 // but double and long take two constant pool entries 215 case JVM_CONSTANT_Double: // fall through 216 case JVM_CONSTANT_Long: 217 { 218 constantPoolOopDesc::copy_entry_to(scratch_cp, scratch_i, *merge_cp_p, *merge_cp_length_p, 219 THREAD); 220 221 if (scratch_i != *merge_cp_length_p) { 222 // The new entry in *merge_cp_p is at a different index than 223 // the new entry in scratch_cp so we need to map the index values. 224 map_index(scratch_cp, scratch_i, *merge_cp_length_p); 225 } 226 (*merge_cp_length_p) += 2; 227 } break; 228 229 // these are direct CP entries so they can be directly appended 230 case JVM_CONSTANT_Float: // fall through 231 case JVM_CONSTANT_Integer: // fall through 232 case JVM_CONSTANT_Utf8: // fall through 233 234 // This was an indirect CP entry, but it has been changed into 235 // an interned string so this entry can be directly appended. 236 case JVM_CONSTANT_String: // fall through 237 238 // These were indirect CP entries, but they have been changed into 239 // Symbol*s so these entries can be directly appended. 240 case JVM_CONSTANT_UnresolvedClass: // fall through 241 case JVM_CONSTANT_UnresolvedString: 242 { 243 constantPoolOopDesc::copy_entry_to(scratch_cp, scratch_i, *merge_cp_p, *merge_cp_length_p, 244 THREAD); 245 246 if (scratch_i != *merge_cp_length_p) { 247 // The new entry in *merge_cp_p is at a different index than 248 // the new entry in scratch_cp so we need to map the index values. 249 map_index(scratch_cp, scratch_i, *merge_cp_length_p); 250 } 251 (*merge_cp_length_p)++; 252 } break; 253 254 // this is an indirect CP entry so it needs special handling 255 case JVM_CONSTANT_NameAndType: 256 { 257 int name_ref_i = scratch_cp->name_ref_index_at(scratch_i); 258 int new_name_ref_i = 0; 259 bool match = (name_ref_i < *merge_cp_length_p) && 260 scratch_cp->compare_entry_to(name_ref_i, *merge_cp_p, name_ref_i, 261 THREAD); 262 if (!match) { 263 // forward reference in *merge_cp_p or not a direct match 264 265 int found_i = scratch_cp->find_matching_entry(name_ref_i, *merge_cp_p, 266 THREAD); 267 if (found_i != 0) { 268 guarantee(found_i != name_ref_i, 269 "compare_entry_to() and find_matching_entry() do not agree"); 270 271 // Found a matching entry somewhere else in *merge_cp_p so 272 // just need a mapping entry. 273 new_name_ref_i = found_i; 274 map_index(scratch_cp, name_ref_i, found_i); 275 } else { 276 // no match found so we have to append this entry to *merge_cp_p 277 append_entry(scratch_cp, name_ref_i, merge_cp_p, merge_cp_length_p, 278 THREAD); 279 // The above call to append_entry() can only append one entry 280 // so the post call query of *merge_cp_length_p is only for 281 // the sake of consistency. 282 new_name_ref_i = *merge_cp_length_p - 1; 283 } 284 } 285 286 int signature_ref_i = scratch_cp->signature_ref_index_at(scratch_i); 287 int new_signature_ref_i = 0; 288 match = (signature_ref_i < *merge_cp_length_p) && 289 scratch_cp->compare_entry_to(signature_ref_i, *merge_cp_p, 290 signature_ref_i, THREAD); 291 if (!match) { 292 // forward reference in *merge_cp_p or not a direct match 293 294 int found_i = scratch_cp->find_matching_entry(signature_ref_i, 295 *merge_cp_p, THREAD); 296 if (found_i != 0) { 297 guarantee(found_i != signature_ref_i, 298 "compare_entry_to() and find_matching_entry() do not agree"); 299 300 // Found a matching entry somewhere else in *merge_cp_p so 301 // just need a mapping entry. 302 new_signature_ref_i = found_i; 303 map_index(scratch_cp, signature_ref_i, found_i); 304 } else { 305 // no match found so we have to append this entry to *merge_cp_p 306 append_entry(scratch_cp, signature_ref_i, merge_cp_p, 307 merge_cp_length_p, THREAD); 308 // The above call to append_entry() can only append one entry 309 // so the post call query of *merge_cp_length_p is only for 310 // the sake of consistency. 311 new_signature_ref_i = *merge_cp_length_p - 1; 312 } 313 } 314 315 // If the referenced entries already exist in *merge_cp_p, then 316 // both new_name_ref_i and new_signature_ref_i will both be 0. 317 // In that case, all we are appending is the current entry. 318 if (new_name_ref_i == 0) { 319 new_name_ref_i = name_ref_i; 320 } else { 321 RC_TRACE(0x00080000, 322 ("NameAndType entry@%d name_ref_index change: %d to %d", 323 *merge_cp_length_p, name_ref_i, new_name_ref_i)); 324 } 325 if (new_signature_ref_i == 0) { 326 new_signature_ref_i = signature_ref_i; 327 } else { 328 RC_TRACE(0x00080000, 329 ("NameAndType entry@%d signature_ref_index change: %d to %d", 330 *merge_cp_length_p, signature_ref_i, new_signature_ref_i)); 331 } 332 333 (*merge_cp_p)->name_and_type_at_put(*merge_cp_length_p, 334 new_name_ref_i, new_signature_ref_i); 335 if (scratch_i != *merge_cp_length_p) { 336 // The new entry in *merge_cp_p is at a different index than 337 // the new entry in scratch_cp so we need to map the index values. 338 map_index(scratch_cp, scratch_i, *merge_cp_length_p); 339 } 340 (*merge_cp_length_p)++; 341 } break; 342 343 // this is a double-indirect CP entry so it needs special handling 344 case JVM_CONSTANT_Fieldref: // fall through 345 case JVM_CONSTANT_InterfaceMethodref: // fall through 346 case JVM_CONSTANT_Methodref: 347 { 348 int klass_ref_i = scratch_cp->uncached_klass_ref_index_at(scratch_i); 349 int new_klass_ref_i = 0; 350 bool match = (klass_ref_i < *merge_cp_length_p) && 351 scratch_cp->compare_entry_to(klass_ref_i, *merge_cp_p, klass_ref_i, 352 THREAD); 353 if (!match) { 354 // forward reference in *merge_cp_p or not a direct match 355 356 int found_i = scratch_cp->find_matching_entry(klass_ref_i, *merge_cp_p, 357 THREAD); 358 if (found_i != 0) { 359 guarantee(found_i != klass_ref_i, 360 "compare_entry_to() and find_matching_entry() do not agree"); 361 362 // Found a matching entry somewhere else in *merge_cp_p so 363 // just need a mapping entry. 364 new_klass_ref_i = found_i; 365 map_index(scratch_cp, klass_ref_i, found_i); 366 } else { 367 // no match found so we have to append this entry to *merge_cp_p 368 append_entry(scratch_cp, klass_ref_i, merge_cp_p, merge_cp_length_p, 369 THREAD); 370 // The above call to append_entry() can only append one entry 371 // so the post call query of *merge_cp_length_p is only for 372 // the sake of consistency. Without the optimization where we 373 // use JVM_CONSTANT_UnresolvedClass, then up to two entries 374 // could be appended. 375 new_klass_ref_i = *merge_cp_length_p - 1; 376 } 377 } 378 379 int name_and_type_ref_i = 380 scratch_cp->uncached_name_and_type_ref_index_at(scratch_i); 381 int new_name_and_type_ref_i = 0; 382 match = (name_and_type_ref_i < *merge_cp_length_p) && 383 scratch_cp->compare_entry_to(name_and_type_ref_i, *merge_cp_p, 384 name_and_type_ref_i, THREAD); 385 if (!match) { 386 // forward reference in *merge_cp_p or not a direct match 387 388 int found_i = scratch_cp->find_matching_entry(name_and_type_ref_i, 389 *merge_cp_p, THREAD); 390 if (found_i != 0) { 391 guarantee(found_i != name_and_type_ref_i, 392 "compare_entry_to() and find_matching_entry() do not agree"); 393 394 // Found a matching entry somewhere else in *merge_cp_p so 395 // just need a mapping entry. 396 new_name_and_type_ref_i = found_i; 397 map_index(scratch_cp, name_and_type_ref_i, found_i); 398 } else { 399 // no match found so we have to append this entry to *merge_cp_p 400 append_entry(scratch_cp, name_and_type_ref_i, merge_cp_p, 401 merge_cp_length_p, THREAD); 402 // The above call to append_entry() can append more than 403 // one entry so the post call query of *merge_cp_length_p 404 // is required in order to get the right index for the 405 // JVM_CONSTANT_NameAndType entry. 406 new_name_and_type_ref_i = *merge_cp_length_p - 1; 407 } 408 } 409 410 // If the referenced entries already exist in *merge_cp_p, then 411 // both new_klass_ref_i and new_name_and_type_ref_i will both be 412 // 0. In that case, all we are appending is the current entry. 413 if (new_klass_ref_i == 0) { 414 new_klass_ref_i = klass_ref_i; 415 } 416 if (new_name_and_type_ref_i == 0) { 417 new_name_and_type_ref_i = name_and_type_ref_i; 418 } 419 420 const char *entry_name; 421 switch (scratch_cp->tag_at(scratch_i).value()) { 422 case JVM_CONSTANT_Fieldref: 423 entry_name = "Fieldref"; 424 (*merge_cp_p)->field_at_put(*merge_cp_length_p, new_klass_ref_i, 425 new_name_and_type_ref_i); 426 break; 427 case JVM_CONSTANT_InterfaceMethodref: 428 entry_name = "IFMethodref"; 429 (*merge_cp_p)->interface_method_at_put(*merge_cp_length_p, 430 new_klass_ref_i, new_name_and_type_ref_i); 431 break; 432 case JVM_CONSTANT_Methodref: 433 entry_name = "Methodref"; 434 (*merge_cp_p)->method_at_put(*merge_cp_length_p, new_klass_ref_i, 435 new_name_and_type_ref_i); 436 break; 437 default: 438 guarantee(false, "bad switch"); 439 break; 440 } 441 442 if (klass_ref_i != new_klass_ref_i) { 443 RC_TRACE(0x00080000, ("%s entry@%d class_index changed: %d to %d", 444 entry_name, *merge_cp_length_p, klass_ref_i, new_klass_ref_i)); 445 } 446 if (name_and_type_ref_i != new_name_and_type_ref_i) { 447 RC_TRACE(0x00080000, 448 ("%s entry@%d name_and_type_index changed: %d to %d", 449 entry_name, *merge_cp_length_p, name_and_type_ref_i, 450 new_name_and_type_ref_i)); 451 } 452 453 if (scratch_i != *merge_cp_length_p) { 454 // The new entry in *merge_cp_p is at a different index than 455 // the new entry in scratch_cp so we need to map the index values. 456 map_index(scratch_cp, scratch_i, *merge_cp_length_p); 457 } 458 (*merge_cp_length_p)++; 459 } break; 460 461 // At this stage, Class or UnresolvedClass could be here, but not 462 // ClassIndex 463 case JVM_CONSTANT_ClassIndex: // fall through 464 465 // Invalid is used as the tag for the second constant pool entry 466 // occupied by JVM_CONSTANT_Double or JVM_CONSTANT_Long. It should 467 // not be seen by itself. 468 case JVM_CONSTANT_Invalid: // fall through 469 470 // At this stage, String or UnresolvedString could be here, but not 471 // StringIndex 472 case JVM_CONSTANT_StringIndex: // fall through 473 474 // At this stage JVM_CONSTANT_UnresolvedClassInError should not be 475 // here 476 case JVM_CONSTANT_UnresolvedClassInError: // fall through 477 478 default: 479 { 480 // leave a breadcrumb 481 jbyte bad_value = scratch_cp->tag_at(scratch_i).value(); 482 ShouldNotReachHere(); 483 } break; 484 } // end switch tag value 485 } // end append_entry() 486 487 488 void VM_RedefineClasses::swap_all_method_annotations(int i, int j, instanceKlassHandle scratch_class) { 489 typeArrayOop save; 490 491 save = scratch_class->get_method_annotations_of(i); 492 scratch_class->set_method_annotations_of(i, scratch_class->get_method_annotations_of(j)); 493 scratch_class->set_method_annotations_of(j, save); 494 495 save = scratch_class->get_method_parameter_annotations_of(i); 496 scratch_class->set_method_parameter_annotations_of(i, scratch_class->get_method_parameter_annotations_of(j)); 497 scratch_class->set_method_parameter_annotations_of(j, save); 498 499 save = scratch_class->get_method_default_annotations_of(i); 500 scratch_class->set_method_default_annotations_of(i, scratch_class->get_method_default_annotations_of(j)); 501 scratch_class->set_method_default_annotations_of(j, save); 502 } 503 504 505 jvmtiError VM_RedefineClasses::compare_and_normalize_class_versions( 506 instanceKlassHandle the_class, 507 instanceKlassHandle scratch_class) { 508 int i; 509 510 // Check superclasses, or rather their names, since superclasses themselves can be 511 // requested to replace. 512 // Check for NULL superclass first since this might be java.lang.Object 513 if (the_class->super() != scratch_class->super() && 514 (the_class->super() == NULL || scratch_class->super() == NULL || 515 Klass::cast(the_class->super())->name() != 516 Klass::cast(scratch_class->super())->name())) { 517 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_HIERARCHY_CHANGED; 518 } 519 520 // Check if the number, names and order of directly implemented interfaces are the same. 521 // I think in principle we should just check if the sets of names of directly implemented 522 // interfaces are the same, i.e. the order of declaration (which, however, if changed in the 523 // .java file, also changes in .class file) should not matter. However, comparing sets is 524 // technically a bit more difficult, and, more importantly, I am not sure at present that the 525 // order of interfaces does not matter on the implementation level, i.e. that the VM does not 526 // rely on it somewhere. 527 objArrayOop k_interfaces = the_class->local_interfaces(); 528 objArrayOop k_new_interfaces = scratch_class->local_interfaces(); 529 int n_intfs = k_interfaces->length(); 530 if (n_intfs != k_new_interfaces->length()) { 531 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_HIERARCHY_CHANGED; 532 } 533 for (i = 0; i < n_intfs; i++) { 534 if (Klass::cast((klassOop) k_interfaces->obj_at(i))->name() != 535 Klass::cast((klassOop) k_new_interfaces->obj_at(i))->name()) { 536 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_HIERARCHY_CHANGED; 537 } 538 } 539 540 // Check whether class is in the error init state. 541 if (the_class->is_in_error_state()) { 542 // TBD #5057930: special error code is needed in 1.6 543 return JVMTI_ERROR_INVALID_CLASS; 544 } 545 546 // Check whether class modifiers are the same. 547 jushort old_flags = (jushort) the_class->access_flags().get_flags(); 548 jushort new_flags = (jushort) scratch_class->access_flags().get_flags(); 549 if (old_flags != new_flags) { 550 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_CLASS_MODIFIERS_CHANGED; 551 } 552 553 // Check if the number, names, types and order of fields declared in these classes 554 // are the same. 555 JavaFieldStream old_fs(the_class); 556 JavaFieldStream new_fs(scratch_class); 557 for (; !old_fs.done() && !new_fs.done(); old_fs.next(), new_fs.next()) { 558 // access 559 old_flags = old_fs.access_flags().as_short(); 560 new_flags = new_fs.access_flags().as_short(); 561 if ((old_flags ^ new_flags) & JVM_RECOGNIZED_FIELD_MODIFIERS) { 562 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_SCHEMA_CHANGED; 563 } 564 // offset 565 if (old_fs.offset() != new_fs.offset()) { 566 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_SCHEMA_CHANGED; 567 } 568 // name and signature 569 Symbol* name_sym1 = the_class->constants()->symbol_at(old_fs.name_index()); 570 Symbol* sig_sym1 = the_class->constants()->symbol_at(old_fs.signature_index()); 571 Symbol* name_sym2 = scratch_class->constants()->symbol_at(new_fs.name_index()); 572 Symbol* sig_sym2 = scratch_class->constants()->symbol_at(new_fs.signature_index()); 573 if (name_sym1 != name_sym2 || sig_sym1 != sig_sym2) { 574 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_SCHEMA_CHANGED; 575 } 576 } 577 578 // If both streams aren't done then we have a differing number of 579 // fields. 580 if (!old_fs.done() || !new_fs.done()) { 581 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_SCHEMA_CHANGED; 582 } 583 584 // Do a parallel walk through the old and new methods. Detect 585 // cases where they match (exist in both), have been added in 586 // the new methods, or have been deleted (exist only in the 587 // old methods). The class file parser places methods in order 588 // by method name, but does not order overloaded methods by 589 // signature. In order to determine what fate befell the methods, 590 // this code places the overloaded new methods that have matching 591 // old methods in the same order as the old methods and places 592 // new overloaded methods at the end of overloaded methods of 593 // that name. The code for this order normalization is adapted 594 // from the algorithm used in instanceKlass::find_method(). 595 // Since we are swapping out of order entries as we find them, 596 // we only have to search forward through the overloaded methods. 597 // Methods which are added and have the same name as an existing 598 // method (but different signature) will be put at the end of 599 // the methods with that name, and the name mismatch code will 600 // handle them. 601 objArrayHandle k_old_methods(the_class->methods()); 602 objArrayHandle k_new_methods(scratch_class->methods()); 603 int n_old_methods = k_old_methods->length(); 604 int n_new_methods = k_new_methods->length(); 605 606 int ni = 0; 607 int oi = 0; 608 while (true) { 609 methodOop k_old_method; 610 methodOop k_new_method; 611 enum { matched, added, deleted, undetermined } method_was = undetermined; 612 613 if (oi >= n_old_methods) { 614 if (ni >= n_new_methods) { 615 break; // we've looked at everything, done 616 } 617 // New method at the end 618 k_new_method = (methodOop) k_new_methods->obj_at(ni); 619 method_was = added; 620 } else if (ni >= n_new_methods) { 621 // Old method, at the end, is deleted 622 k_old_method = (methodOop) k_old_methods->obj_at(oi); 623 method_was = deleted; 624 } else { 625 // There are more methods in both the old and new lists 626 k_old_method = (methodOop) k_old_methods->obj_at(oi); 627 k_new_method = (methodOop) k_new_methods->obj_at(ni); 628 if (k_old_method->name() != k_new_method->name()) { 629 // Methods are sorted by method name, so a mismatch means added 630 // or deleted 631 if (k_old_method->name()->fast_compare(k_new_method->name()) > 0) { 632 method_was = added; 633 } else { 634 method_was = deleted; 635 } 636 } else if (k_old_method->signature() == k_new_method->signature()) { 637 // Both the name and signature match 638 method_was = matched; 639 } else { 640 // The name matches, but the signature doesn't, which means we have to 641 // search forward through the new overloaded methods. 642 int nj; // outside the loop for post-loop check 643 for (nj = ni + 1; nj < n_new_methods; nj++) { 644 methodOop m = (methodOop)k_new_methods->obj_at(nj); 645 if (k_old_method->name() != m->name()) { 646 // reached another method name so no more overloaded methods 647 method_was = deleted; 648 break; 649 } 650 if (k_old_method->signature() == m->signature()) { 651 // found a match so swap the methods 652 k_new_methods->obj_at_put(ni, m); 653 k_new_methods->obj_at_put(nj, k_new_method); 654 k_new_method = m; 655 method_was = matched; 656 break; 657 } 658 } 659 660 if (nj >= n_new_methods) { 661 // reached the end without a match; so method was deleted 662 method_was = deleted; 663 } 664 } 665 } 666 667 switch (method_was) { 668 case matched: 669 // methods match, be sure modifiers do too 670 old_flags = (jushort) k_old_method->access_flags().get_flags(); 671 new_flags = (jushort) k_new_method->access_flags().get_flags(); 672 if ((old_flags ^ new_flags) & ~(JVM_ACC_NATIVE)) { 673 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_METHOD_MODIFIERS_CHANGED; 674 } 675 { 676 u2 new_num = k_new_method->method_idnum(); 677 u2 old_num = k_old_method->method_idnum(); 678 if (new_num != old_num) { 679 methodOop idnum_owner = scratch_class->method_with_idnum(old_num); 680 if (idnum_owner != NULL) { 681 // There is already a method assigned this idnum -- switch them 682 idnum_owner->set_method_idnum(new_num); 683 } 684 k_new_method->set_method_idnum(old_num); 685 swap_all_method_annotations(old_num, new_num, scratch_class); 686 } 687 } 688 RC_TRACE(0x00008000, ("Method matched: new: %s [%d] == old: %s [%d]", 689 k_new_method->name_and_sig_as_C_string(), ni, 690 k_old_method->name_and_sig_as_C_string(), oi)); 691 // advance to next pair of methods 692 ++oi; 693 ++ni; 694 break; 695 case added: 696 // method added, see if it is OK 697 new_flags = (jushort) k_new_method->access_flags().get_flags(); 698 if ((new_flags & JVM_ACC_PRIVATE) == 0 699 // hack: private should be treated as final, but alas 700 || (new_flags & (JVM_ACC_FINAL|JVM_ACC_STATIC)) == 0 701 ) { 702 // new methods must be private 703 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_METHOD_ADDED; 704 } 705 { 706 u2 num = the_class->next_method_idnum(); 707 if (num == constMethodOopDesc::UNSET_IDNUM) { 708 // cannot add any more methods 709 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_METHOD_ADDED; 710 } 711 u2 new_num = k_new_method->method_idnum(); 712 methodOop idnum_owner = scratch_class->method_with_idnum(num); 713 if (idnum_owner != NULL) { 714 // There is already a method assigned this idnum -- switch them 715 idnum_owner->set_method_idnum(new_num); 716 } 717 k_new_method->set_method_idnum(num); 718 swap_all_method_annotations(new_num, num, scratch_class); 719 } 720 RC_TRACE(0x00008000, ("Method added: new: %s [%d]", 721 k_new_method->name_and_sig_as_C_string(), ni)); 722 ++ni; // advance to next new method 723 break; 724 case deleted: 725 // method deleted, see if it is OK 726 old_flags = (jushort) k_old_method->access_flags().get_flags(); 727 if ((old_flags & JVM_ACC_PRIVATE) == 0 728 // hack: private should be treated as final, but alas 729 || (old_flags & (JVM_ACC_FINAL|JVM_ACC_STATIC)) == 0 730 ) { 731 // deleted methods must be private 732 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_METHOD_DELETED; 733 } 734 RC_TRACE(0x00008000, ("Method deleted: old: %s [%d]", 735 k_old_method->name_and_sig_as_C_string(), oi)); 736 ++oi; // advance to next old method 737 break; 738 default: 739 ShouldNotReachHere(); 740 } 741 } 742 743 return JVMTI_ERROR_NONE; 744 } 745 746 747 // Find new constant pool index value for old constant pool index value 748 // by seaching the index map. Returns zero (0) if there is no mapped 749 // value for the old constant pool index. 750 int VM_RedefineClasses::find_new_index(int old_index) { 751 if (_index_map_count == 0) { 752 // map is empty so nothing can be found 753 return 0; 754 } 755 756 if (old_index < 1 || old_index >= _index_map_p->length()) { 757 // The old_index is out of range so it is not mapped. This should 758 // not happen in regular constant pool merging use, but it can 759 // happen if a corrupt annotation is processed. 760 return 0; 761 } 762 763 int value = _index_map_p->at(old_index); 764 if (value == -1) { 765 // the old_index is not mapped 766 return 0; 767 } 768 769 return value; 770 } // end find_new_index() 771 772 773 // Returns true if the current mismatch is due to a resolved/unresolved 774 // class pair. Otherwise, returns false. 775 bool VM_RedefineClasses::is_unresolved_class_mismatch(constantPoolHandle cp1, 776 int index1, constantPoolHandle cp2, int index2) { 777 778 jbyte t1 = cp1->tag_at(index1).value(); 779 if (t1 != JVM_CONSTANT_Class && t1 != JVM_CONSTANT_UnresolvedClass) { 780 return false; // wrong entry type; not our special case 781 } 782 783 jbyte t2 = cp2->tag_at(index2).value(); 784 if (t2 != JVM_CONSTANT_Class && t2 != JVM_CONSTANT_UnresolvedClass) { 785 return false; // wrong entry type; not our special case 786 } 787 788 if (t1 == t2) { 789 return false; // not a mismatch; not our special case 790 } 791 792 char *s1 = cp1->klass_name_at(index1)->as_C_string(); 793 char *s2 = cp2->klass_name_at(index2)->as_C_string(); 794 if (strcmp(s1, s2) != 0) { 795 return false; // strings don't match; not our special case 796 } 797 798 return true; // made it through the gauntlet; this is our special case 799 } // end is_unresolved_class_mismatch() 800 801 802 // Returns true if the current mismatch is due to a resolved/unresolved 803 // string pair. Otherwise, returns false. 804 bool VM_RedefineClasses::is_unresolved_string_mismatch(constantPoolHandle cp1, 805 int index1, constantPoolHandle cp2, int index2) { 806 807 jbyte t1 = cp1->tag_at(index1).value(); 808 if (t1 != JVM_CONSTANT_String && t1 != JVM_CONSTANT_UnresolvedString) { 809 return false; // wrong entry type; not our special case 810 } 811 812 jbyte t2 = cp2->tag_at(index2).value(); 813 if (t2 != JVM_CONSTANT_String && t2 != JVM_CONSTANT_UnresolvedString) { 814 return false; // wrong entry type; not our special case 815 } 816 817 if (t1 == t2) { 818 return false; // not a mismatch; not our special case 819 } 820 821 char *s1 = cp1->string_at_noresolve(index1); 822 char *s2 = cp2->string_at_noresolve(index2); 823 if (strcmp(s1, s2) != 0) { 824 return false; // strings don't match; not our special case 825 } 826 827 return true; // made it through the gauntlet; this is our special case 828 } // end is_unresolved_string_mismatch() 829 830 831 jvmtiError VM_RedefineClasses::load_new_class_versions(TRAPS) { 832 // For consistency allocate memory using os::malloc wrapper. 833 _scratch_classes = (instanceKlassHandle *) 834 os::malloc(sizeof(instanceKlassHandle) * _class_count); 835 if (_scratch_classes == NULL) { 836 return JVMTI_ERROR_OUT_OF_MEMORY; 837 } 838 839 ResourceMark rm(THREAD); 840 841 JvmtiThreadState *state = JvmtiThreadState::state_for(JavaThread::current()); 842 // state can only be NULL if the current thread is exiting which 843 // should not happen since we're trying to do a RedefineClasses 844 guarantee(state != NULL, "exiting thread calling load_new_class_versions"); 845 for (int i = 0; i < _class_count; i++) { 846 oop mirror = JNIHandles::resolve_non_null(_class_defs[i].klass); 847 // classes for primitives cannot be redefined 848 if (!is_modifiable_class(mirror)) { 849 return JVMTI_ERROR_UNMODIFIABLE_CLASS; 850 } 851 klassOop the_class_oop = java_lang_Class::as_klassOop(mirror); 852 instanceKlassHandle the_class = instanceKlassHandle(THREAD, the_class_oop); 853 Symbol* the_class_sym = the_class->name(); 854 855 // RC_TRACE_WITH_THREAD macro has an embedded ResourceMark 856 RC_TRACE_WITH_THREAD(0x00000001, THREAD, 857 ("loading name=%s kind=%d (avail_mem=" UINT64_FORMAT "K)", 858 the_class->external_name(), _class_load_kind, 859 os::available_memory() >> 10)); 860 861 ClassFileStream st((u1*) _class_defs[i].class_bytes, 862 _class_defs[i].class_byte_count, (char *)"__VM_RedefineClasses__"); 863 864 // Parse the stream. 865 Handle the_class_loader(THREAD, the_class->class_loader()); 866 Handle protection_domain(THREAD, the_class->protection_domain()); 867 // Set redefined class handle in JvmtiThreadState class. 868 // This redefined class is sent to agent event handler for class file 869 // load hook event. 870 state->set_class_being_redefined(&the_class, _class_load_kind); 871 872 klassOop k = SystemDictionary::parse_stream(the_class_sym, 873 the_class_loader, 874 protection_domain, 875 &st, 876 THREAD); 877 // Clear class_being_redefined just to be sure. 878 state->clear_class_being_redefined(); 879 880 // TODO: if this is retransform, and nothing changed we can skip it 881 882 instanceKlassHandle scratch_class (THREAD, k); 883 884 if (HAS_PENDING_EXCEPTION) { 885 Symbol* ex_name = PENDING_EXCEPTION->klass()->klass_part()->name(); 886 // RC_TRACE_WITH_THREAD macro has an embedded ResourceMark 887 RC_TRACE_WITH_THREAD(0x00000002, THREAD, ("parse_stream exception: '%s'", 888 ex_name->as_C_string())); 889 CLEAR_PENDING_EXCEPTION; 890 891 if (ex_name == vmSymbols::java_lang_UnsupportedClassVersionError()) { 892 return JVMTI_ERROR_UNSUPPORTED_VERSION; 893 } else if (ex_name == vmSymbols::java_lang_ClassFormatError()) { 894 return JVMTI_ERROR_INVALID_CLASS_FORMAT; 895 } else if (ex_name == vmSymbols::java_lang_ClassCircularityError()) { 896 return JVMTI_ERROR_CIRCULAR_CLASS_DEFINITION; 897 } else if (ex_name == vmSymbols::java_lang_NoClassDefFoundError()) { 898 // The message will be "XXX (wrong name: YYY)" 899 return JVMTI_ERROR_NAMES_DONT_MATCH; 900 } else if (ex_name == vmSymbols::java_lang_OutOfMemoryError()) { 901 return JVMTI_ERROR_OUT_OF_MEMORY; 902 } else { // Just in case more exceptions can be thrown.. 903 return JVMTI_ERROR_FAILS_VERIFICATION; 904 } 905 } 906 907 // Ensure class is linked before redefine 908 if (!the_class->is_linked()) { 909 the_class->link_class(THREAD); 910 if (HAS_PENDING_EXCEPTION) { 911 Symbol* ex_name = PENDING_EXCEPTION->klass()->klass_part()->name(); 912 // RC_TRACE_WITH_THREAD macro has an embedded ResourceMark 913 RC_TRACE_WITH_THREAD(0x00000002, THREAD, ("link_class exception: '%s'", 914 ex_name->as_C_string())); 915 CLEAR_PENDING_EXCEPTION; 916 if (ex_name == vmSymbols::java_lang_OutOfMemoryError()) { 917 return JVMTI_ERROR_OUT_OF_MEMORY; 918 } else { 919 return JVMTI_ERROR_INTERNAL; 920 } 921 } 922 } 923 924 // Do the validity checks in compare_and_normalize_class_versions() 925 // before verifying the byte codes. By doing these checks first, we 926 // limit the number of functions that require redirection from 927 // the_class to scratch_class. In particular, we don't have to 928 // modify JNI GetSuperclass() and thus won't change its performance. 929 jvmtiError res = compare_and_normalize_class_versions(the_class, 930 scratch_class); 931 if (res != JVMTI_ERROR_NONE) { 932 return res; 933 } 934 935 // verify what the caller passed us 936 { 937 // The bug 6214132 caused the verification to fail. 938 // Information about the_class and scratch_class is temporarily 939 // recorded into jvmtiThreadState. This data is used to redirect 940 // the_class to scratch_class in the JVM_* functions called by the 941 // verifier. Please, refer to jvmtiThreadState.hpp for the detailed 942 // description. 943 RedefineVerifyMark rvm(&the_class, &scratch_class, state); 944 Verifier::verify( 945 scratch_class, Verifier::ThrowException, true, THREAD); 946 } 947 948 if (HAS_PENDING_EXCEPTION) { 949 Symbol* ex_name = PENDING_EXCEPTION->klass()->klass_part()->name(); 950 // RC_TRACE_WITH_THREAD macro has an embedded ResourceMark 951 RC_TRACE_WITH_THREAD(0x00000002, THREAD, 952 ("verify_byte_codes exception: '%s'", ex_name->as_C_string())); 953 CLEAR_PENDING_EXCEPTION; 954 if (ex_name == vmSymbols::java_lang_OutOfMemoryError()) { 955 return JVMTI_ERROR_OUT_OF_MEMORY; 956 } else { 957 // tell the caller the bytecodes are bad 958 return JVMTI_ERROR_FAILS_VERIFICATION; 959 } 960 } 961 962 res = merge_cp_and_rewrite(the_class, scratch_class, THREAD); 963 if (res != JVMTI_ERROR_NONE) { 964 return res; 965 } 966 967 if (VerifyMergedCPBytecodes) { 968 // verify what we have done during constant pool merging 969 { 970 RedefineVerifyMark rvm(&the_class, &scratch_class, state); 971 Verifier::verify(scratch_class, Verifier::ThrowException, true, THREAD); 972 } 973 974 if (HAS_PENDING_EXCEPTION) { 975 Symbol* ex_name = PENDING_EXCEPTION->klass()->klass_part()->name(); 976 // RC_TRACE_WITH_THREAD macro has an embedded ResourceMark 977 RC_TRACE_WITH_THREAD(0x00000002, THREAD, 978 ("verify_byte_codes post merge-CP exception: '%s'", 979 ex_name->as_C_string())); 980 CLEAR_PENDING_EXCEPTION; 981 if (ex_name == vmSymbols::java_lang_OutOfMemoryError()) { 982 return JVMTI_ERROR_OUT_OF_MEMORY; 983 } else { 984 // tell the caller that constant pool merging screwed up 985 return JVMTI_ERROR_INTERNAL; 986 } 987 } 988 } 989 990 Rewriter::rewrite(scratch_class, THREAD); 991 if (!HAS_PENDING_EXCEPTION) { 992 Rewriter::relocate_and_link(scratch_class, THREAD); 993 } 994 if (HAS_PENDING_EXCEPTION) { 995 Symbol* ex_name = PENDING_EXCEPTION->klass()->klass_part()->name(); 996 CLEAR_PENDING_EXCEPTION; 997 if (ex_name == vmSymbols::java_lang_OutOfMemoryError()) { 998 return JVMTI_ERROR_OUT_OF_MEMORY; 999 } else { 1000 return JVMTI_ERROR_INTERNAL; 1001 } 1002 } 1003 1004 _scratch_classes[i] = scratch_class; 1005 1006 // RC_TRACE_WITH_THREAD macro has an embedded ResourceMark 1007 RC_TRACE_WITH_THREAD(0x00000001, THREAD, 1008 ("loaded name=%s (avail_mem=" UINT64_FORMAT "K)", 1009 the_class->external_name(), os::available_memory() >> 10)); 1010 } 1011 1012 return JVMTI_ERROR_NONE; 1013 } 1014 1015 1016 // Map old_index to new_index as needed. scratch_cp is only needed 1017 // for RC_TRACE() calls. 1018 void VM_RedefineClasses::map_index(constantPoolHandle scratch_cp, 1019 int old_index, int new_index) { 1020 if (find_new_index(old_index) != 0) { 1021 // old_index is already mapped 1022 return; 1023 } 1024 1025 if (old_index == new_index) { 1026 // no mapping is needed 1027 return; 1028 } 1029 1030 _index_map_p->at_put(old_index, new_index); 1031 _index_map_count++; 1032 1033 RC_TRACE(0x00040000, ("mapped tag %d at index %d to %d", 1034 scratch_cp->tag_at(old_index).value(), old_index, new_index)); 1035 } // end map_index() 1036 1037 1038 // Merge old_cp and scratch_cp and return the results of the merge via 1039 // merge_cp_p. The number of entries in *merge_cp_p is returned via 1040 // merge_cp_length_p. The entries in old_cp occupy the same locations 1041 // in *merge_cp_p. Also creates a map of indices from entries in 1042 // scratch_cp to the corresponding entry in *merge_cp_p. Index map 1043 // entries are only created for entries in scratch_cp that occupy a 1044 // different location in *merged_cp_p. 1045 bool VM_RedefineClasses::merge_constant_pools(constantPoolHandle old_cp, 1046 constantPoolHandle scratch_cp, constantPoolHandle *merge_cp_p, 1047 int *merge_cp_length_p, TRAPS) { 1048 1049 if (merge_cp_p == NULL) { 1050 assert(false, "caller must provide scatch constantPool"); 1051 return false; // robustness 1052 } 1053 if (merge_cp_length_p == NULL) { 1054 assert(false, "caller must provide scatch CP length"); 1055 return false; // robustness 1056 } 1057 // Worst case we need old_cp->length() + scratch_cp()->length(), 1058 // but the caller might be smart so make sure we have at least 1059 // the minimum. 1060 if ((*merge_cp_p)->length() < old_cp->length()) { 1061 assert(false, "merge area too small"); 1062 return false; // robustness 1063 } 1064 1065 RC_TRACE_WITH_THREAD(0x00010000, THREAD, 1066 ("old_cp_len=%d, scratch_cp_len=%d", old_cp->length(), 1067 scratch_cp->length())); 1068 1069 { 1070 // Pass 0: 1071 // The old_cp is copied to *merge_cp_p; this means that any code 1072 // using old_cp does not have to change. This work looks like a 1073 // perfect fit for constantPoolOop::copy_cp_to(), but we need to 1074 // handle one special case: 1075 // - revert JVM_CONSTANT_Class to JVM_CONSTANT_UnresolvedClass 1076 // This will make verification happy. 1077 1078 int old_i; // index into old_cp 1079 1080 // index zero (0) is not used in constantPools 1081 for (old_i = 1; old_i < old_cp->length(); old_i++) { 1082 // leave debugging crumb 1083 jbyte old_tag = old_cp->tag_at(old_i).value(); 1084 switch (old_tag) { 1085 case JVM_CONSTANT_Class: 1086 case JVM_CONSTANT_UnresolvedClass: 1087 // revert the copy to JVM_CONSTANT_UnresolvedClass 1088 // May be resolving while calling this so do the same for 1089 // JVM_CONSTANT_UnresolvedClass (klass_name_at() deals with transition) 1090 (*merge_cp_p)->unresolved_klass_at_put(old_i, 1091 old_cp->klass_name_at(old_i)); 1092 break; 1093 1094 case JVM_CONSTANT_Double: 1095 case JVM_CONSTANT_Long: 1096 // just copy the entry to *merge_cp_p, but double and long take 1097 // two constant pool entries 1098 constantPoolOopDesc::copy_entry_to(old_cp, old_i, *merge_cp_p, old_i, CHECK_0); 1099 old_i++; 1100 break; 1101 1102 default: 1103 // just copy the entry to *merge_cp_p 1104 constantPoolOopDesc::copy_entry_to(old_cp, old_i, *merge_cp_p, old_i, CHECK_0); 1105 break; 1106 } 1107 } // end for each old_cp entry 1108 1109 // We don't need to sanity check that *merge_cp_length_p is within 1110 // *merge_cp_p bounds since we have the minimum on-entry check above. 1111 (*merge_cp_length_p) = old_i; 1112 } 1113 1114 // merge_cp_len should be the same as old_cp->length() at this point 1115 // so this trace message is really a "warm-and-breathing" message. 1116 RC_TRACE_WITH_THREAD(0x00020000, THREAD, 1117 ("after pass 0: merge_cp_len=%d", *merge_cp_length_p)); 1118 1119 int scratch_i; // index into scratch_cp 1120 { 1121 // Pass 1a: 1122 // Compare scratch_cp entries to the old_cp entries that we have 1123 // already copied to *merge_cp_p. In this pass, we are eliminating 1124 // exact duplicates (matching entry at same index) so we only 1125 // compare entries in the common indice range. 1126 int increment = 1; 1127 int pass1a_length = MIN2(old_cp->length(), scratch_cp->length()); 1128 for (scratch_i = 1; scratch_i < pass1a_length; scratch_i += increment) { 1129 switch (scratch_cp->tag_at(scratch_i).value()) { 1130 case JVM_CONSTANT_Double: 1131 case JVM_CONSTANT_Long: 1132 // double and long take two constant pool entries 1133 increment = 2; 1134 break; 1135 1136 default: 1137 increment = 1; 1138 break; 1139 } 1140 1141 bool match = scratch_cp->compare_entry_to(scratch_i, *merge_cp_p, 1142 scratch_i, CHECK_0); 1143 if (match) { 1144 // found a match at the same index so nothing more to do 1145 continue; 1146 } else if (is_unresolved_class_mismatch(scratch_cp, scratch_i, 1147 *merge_cp_p, scratch_i)) { 1148 // The mismatch in compare_entry_to() above is because of a 1149 // resolved versus unresolved class entry at the same index 1150 // with the same string value. Since Pass 0 reverted any 1151 // class entries to unresolved class entries in *merge_cp_p, 1152 // we go with the unresolved class entry. 1153 continue; 1154 } else if (is_unresolved_string_mismatch(scratch_cp, scratch_i, 1155 *merge_cp_p, scratch_i)) { 1156 // The mismatch in compare_entry_to() above is because of a 1157 // resolved versus unresolved string entry at the same index 1158 // with the same string value. We can live with whichever 1159 // happens to be at scratch_i in *merge_cp_p. 1160 continue; 1161 } 1162 1163 int found_i = scratch_cp->find_matching_entry(scratch_i, *merge_cp_p, 1164 CHECK_0); 1165 if (found_i != 0) { 1166 guarantee(found_i != scratch_i, 1167 "compare_entry_to() and find_matching_entry() do not agree"); 1168 1169 // Found a matching entry somewhere else in *merge_cp_p so 1170 // just need a mapping entry. 1171 map_index(scratch_cp, scratch_i, found_i); 1172 continue; 1173 } 1174 1175 // The find_matching_entry() call above could fail to find a match 1176 // due to a resolved versus unresolved class or string entry situation 1177 // like we solved above with the is_unresolved_*_mismatch() calls. 1178 // However, we would have to call is_unresolved_*_mismatch() over 1179 // all of *merge_cp_p (potentially) and that doesn't seem to be 1180 // worth the time. 1181 1182 // No match found so we have to append this entry and any unique 1183 // referenced entries to *merge_cp_p. 1184 append_entry(scratch_cp, scratch_i, merge_cp_p, merge_cp_length_p, 1185 CHECK_0); 1186 } 1187 } 1188 1189 RC_TRACE_WITH_THREAD(0x00020000, THREAD, 1190 ("after pass 1a: merge_cp_len=%d, scratch_i=%d, index_map_len=%d", 1191 *merge_cp_length_p, scratch_i, _index_map_count)); 1192 1193 if (scratch_i < scratch_cp->length()) { 1194 // Pass 1b: 1195 // old_cp is smaller than scratch_cp so there are entries in 1196 // scratch_cp that we have not yet processed. We take care of 1197 // those now. 1198 int increment = 1; 1199 for (; scratch_i < scratch_cp->length(); scratch_i += increment) { 1200 switch (scratch_cp->tag_at(scratch_i).value()) { 1201 case JVM_CONSTANT_Double: 1202 case JVM_CONSTANT_Long: 1203 // double and long take two constant pool entries 1204 increment = 2; 1205 break; 1206 1207 default: 1208 increment = 1; 1209 break; 1210 } 1211 1212 int found_i = 1213 scratch_cp->find_matching_entry(scratch_i, *merge_cp_p, CHECK_0); 1214 if (found_i != 0) { 1215 // Found a matching entry somewhere else in *merge_cp_p so 1216 // just need a mapping entry. 1217 map_index(scratch_cp, scratch_i, found_i); 1218 continue; 1219 } 1220 1221 // No match found so we have to append this entry and any unique 1222 // referenced entries to *merge_cp_p. 1223 append_entry(scratch_cp, scratch_i, merge_cp_p, merge_cp_length_p, 1224 CHECK_0); 1225 } 1226 1227 RC_TRACE_WITH_THREAD(0x00020000, THREAD, 1228 ("after pass 1b: merge_cp_len=%d, scratch_i=%d, index_map_len=%d", 1229 *merge_cp_length_p, scratch_i, _index_map_count)); 1230 } 1231 1232 return true; 1233 } // end merge_constant_pools() 1234 1235 1236 // Merge constant pools between the_class and scratch_class and 1237 // potentially rewrite bytecodes in scratch_class to use the merged 1238 // constant pool. 1239 jvmtiError VM_RedefineClasses::merge_cp_and_rewrite( 1240 instanceKlassHandle the_class, instanceKlassHandle scratch_class, 1241 TRAPS) { 1242 // worst case merged constant pool length is old and new combined 1243 int merge_cp_length = the_class->constants()->length() 1244 + scratch_class->constants()->length(); 1245 1246 constantPoolHandle old_cp(THREAD, the_class->constants()); 1247 constantPoolHandle scratch_cp(THREAD, scratch_class->constants()); 1248 1249 // Constant pools are not easily reused so we allocate a new one 1250 // each time. 1251 // merge_cp is created unsafe for concurrent GC processing. It 1252 // should be marked safe before discarding it. Even though 1253 // garbage, if it crosses a card boundary, it may be scanned 1254 // in order to find the start of the first complete object on the card. 1255 constantPoolHandle merge_cp(THREAD, 1256 oopFactory::new_constantPool(merge_cp_length, 1257 oopDesc::IsUnsafeConc, 1258 THREAD)); 1259 int orig_length = old_cp->orig_length(); 1260 if (orig_length == 0) { 1261 // This old_cp is an actual original constant pool. We save 1262 // the original length in the merged constant pool so that 1263 // merge_constant_pools() can be more efficient. If a constant 1264 // pool has a non-zero orig_length() value, then that constant 1265 // pool was created by a merge operation in RedefineClasses. 1266 merge_cp->set_orig_length(old_cp->length()); 1267 } else { 1268 // This old_cp is a merged constant pool from a previous 1269 // RedefineClasses() calls so just copy the orig_length() 1270 // value. 1271 merge_cp->set_orig_length(old_cp->orig_length()); 1272 } 1273 1274 ResourceMark rm(THREAD); 1275 _index_map_count = 0; 1276 _index_map_p = new intArray(scratch_cp->length(), -1); 1277 1278 bool result = merge_constant_pools(old_cp, scratch_cp, &merge_cp, 1279 &merge_cp_length, THREAD); 1280 if (!result) { 1281 // The merge can fail due to memory allocation failure or due 1282 // to robustness checks. 1283 return JVMTI_ERROR_INTERNAL; 1284 } 1285 1286 RC_TRACE_WITH_THREAD(0x00010000, THREAD, 1287 ("merge_cp_len=%d, index_map_len=%d", merge_cp_length, _index_map_count)); 1288 1289 if (_index_map_count == 0) { 1290 // there is nothing to map between the new and merged constant pools 1291 1292 if (old_cp->length() == scratch_cp->length()) { 1293 // The old and new constant pools are the same length and the 1294 // index map is empty. This means that the three constant pools 1295 // are equivalent (but not the same). Unfortunately, the new 1296 // constant pool has not gone through link resolution nor have 1297 // the new class bytecodes gone through constant pool cache 1298 // rewriting so we can't use the old constant pool with the new 1299 // class. 1300 1301 merge_cp()->set_is_conc_safe(true); 1302 merge_cp = constantPoolHandle(); // toss the merged constant pool 1303 } else if (old_cp->length() < scratch_cp->length()) { 1304 // The old constant pool has fewer entries than the new constant 1305 // pool and the index map is empty. This means the new constant 1306 // pool is a superset of the old constant pool. However, the old 1307 // class bytecodes have already gone through constant pool cache 1308 // rewriting so we can't use the new constant pool with the old 1309 // class. 1310 1311 merge_cp()->set_is_conc_safe(true); 1312 merge_cp = constantPoolHandle(); // toss the merged constant pool 1313 } else { 1314 // The old constant pool has more entries than the new constant 1315 // pool and the index map is empty. This means that both the old 1316 // and merged constant pools are supersets of the new constant 1317 // pool. 1318 1319 // Replace the new constant pool with a shrunken copy of the 1320 // merged constant pool; the previous new constant pool will 1321 // get GCed. 1322 set_new_constant_pool(scratch_class, merge_cp, merge_cp_length, true, 1323 THREAD); 1324 // drop local ref to the merged constant pool 1325 merge_cp()->set_is_conc_safe(true); 1326 merge_cp = constantPoolHandle(); 1327 } 1328 } else { 1329 if (RC_TRACE_ENABLED(0x00040000)) { 1330 // don't want to loop unless we are tracing 1331 int count = 0; 1332 for (int i = 1; i < _index_map_p->length(); i++) { 1333 int value = _index_map_p->at(i); 1334 1335 if (value != -1) { 1336 RC_TRACE_WITH_THREAD(0x00040000, THREAD, 1337 ("index_map[%d]: old=%d new=%d", count, i, value)); 1338 count++; 1339 } 1340 } 1341 } 1342 1343 // We have entries mapped between the new and merged constant pools 1344 // so we have to rewrite some constant pool references. 1345 if (!rewrite_cp_refs(scratch_class, THREAD)) { 1346 return JVMTI_ERROR_INTERNAL; 1347 } 1348 1349 // Replace the new constant pool with a shrunken copy of the 1350 // merged constant pool so now the rewritten bytecodes have 1351 // valid references; the previous new constant pool will get 1352 // GCed. 1353 set_new_constant_pool(scratch_class, merge_cp, merge_cp_length, true, 1354 THREAD); 1355 merge_cp()->set_is_conc_safe(true); 1356 } 1357 assert(old_cp()->is_conc_safe(), "Just checking"); 1358 assert(scratch_cp()->is_conc_safe(), "Just checking"); 1359 1360 return JVMTI_ERROR_NONE; 1361 } // end merge_cp_and_rewrite() 1362 1363 1364 // Rewrite constant pool references in klass scratch_class. 1365 bool VM_RedefineClasses::rewrite_cp_refs(instanceKlassHandle scratch_class, 1366 TRAPS) { 1367 1368 // rewrite constant pool references in the methods: 1369 if (!rewrite_cp_refs_in_methods(scratch_class, THREAD)) { 1370 // propagate failure back to caller 1371 return false; 1372 } 1373 1374 // rewrite constant pool references in the class_annotations: 1375 if (!rewrite_cp_refs_in_class_annotations(scratch_class, THREAD)) { 1376 // propagate failure back to caller 1377 return false; 1378 } 1379 1380 // rewrite constant pool references in the fields_annotations: 1381 if (!rewrite_cp_refs_in_fields_annotations(scratch_class, THREAD)) { 1382 // propagate failure back to caller 1383 return false; 1384 } 1385 1386 // rewrite constant pool references in the methods_annotations: 1387 if (!rewrite_cp_refs_in_methods_annotations(scratch_class, THREAD)) { 1388 // propagate failure back to caller 1389 return false; 1390 } 1391 1392 // rewrite constant pool references in the methods_parameter_annotations: 1393 if (!rewrite_cp_refs_in_methods_parameter_annotations(scratch_class, 1394 THREAD)) { 1395 // propagate failure back to caller 1396 return false; 1397 } 1398 1399 // rewrite constant pool references in the methods_default_annotations: 1400 if (!rewrite_cp_refs_in_methods_default_annotations(scratch_class, 1401 THREAD)) { 1402 // propagate failure back to caller 1403 return false; 1404 } 1405 1406 return true; 1407 } // end rewrite_cp_refs() 1408 1409 1410 // Rewrite constant pool references in the methods. 1411 bool VM_RedefineClasses::rewrite_cp_refs_in_methods( 1412 instanceKlassHandle scratch_class, TRAPS) { 1413 1414 objArrayHandle methods(THREAD, scratch_class->methods()); 1415 1416 if (methods.is_null() || methods->length() == 0) { 1417 // no methods so nothing to do 1418 return true; 1419 } 1420 1421 // rewrite constant pool references in the methods: 1422 for (int i = methods->length() - 1; i >= 0; i--) { 1423 methodHandle method(THREAD, (methodOop)methods->obj_at(i)); 1424 methodHandle new_method; 1425 rewrite_cp_refs_in_method(method, &new_method, CHECK_false); 1426 if (!new_method.is_null()) { 1427 // the method has been replaced so save the new method version 1428 methods->obj_at_put(i, new_method()); 1429 } 1430 } 1431 1432 return true; 1433 } 1434 1435 1436 // Rewrite constant pool references in the specific method. This code 1437 // was adapted from Rewriter::rewrite_method(). 1438 void VM_RedefineClasses::rewrite_cp_refs_in_method(methodHandle method, 1439 methodHandle *new_method_p, TRAPS) { 1440 1441 *new_method_p = methodHandle(); // default is no new method 1442 1443 // We cache a pointer to the bytecodes here in code_base. If GC 1444 // moves the methodOop, then the bytecodes will also move which 1445 // will likely cause a crash. We create a No_Safepoint_Verifier 1446 // object to detect whether we pass a possible safepoint in this 1447 // code block. 1448 No_Safepoint_Verifier nsv; 1449 1450 // Bytecodes and their length 1451 address code_base = method->code_base(); 1452 int code_length = method->code_size(); 1453 1454 int bc_length; 1455 for (int bci = 0; bci < code_length; bci += bc_length) { 1456 address bcp = code_base + bci; 1457 Bytecodes::Code c = (Bytecodes::Code)(*bcp); 1458 1459 bc_length = Bytecodes::length_for(c); 1460 if (bc_length == 0) { 1461 // More complicated bytecodes report a length of zero so 1462 // we have to try again a slightly different way. 1463 bc_length = Bytecodes::length_at(method(), bcp); 1464 } 1465 1466 assert(bc_length != 0, "impossible bytecode length"); 1467 1468 switch (c) { 1469 case Bytecodes::_ldc: 1470 { 1471 int cp_index = *(bcp + 1); 1472 int new_index = find_new_index(cp_index); 1473 1474 if (StressLdcRewrite && new_index == 0) { 1475 // If we are stressing ldc -> ldc_w rewriting, then we 1476 // always need a new_index value. 1477 new_index = cp_index; 1478 } 1479 if (new_index != 0) { 1480 // the original index is mapped so we have more work to do 1481 if (!StressLdcRewrite && new_index <= max_jubyte) { 1482 // The new value can still use ldc instead of ldc_w 1483 // unless we are trying to stress ldc -> ldc_w rewriting 1484 RC_TRACE_WITH_THREAD(0x00080000, THREAD, 1485 ("%s@" INTPTR_FORMAT " old=%d, new=%d", Bytecodes::name(c), 1486 bcp, cp_index, new_index)); 1487 *(bcp + 1) = new_index; 1488 } else { 1489 RC_TRACE_WITH_THREAD(0x00080000, THREAD, 1490 ("%s->ldc_w@" INTPTR_FORMAT " old=%d, new=%d", 1491 Bytecodes::name(c), bcp, cp_index, new_index)); 1492 // the new value needs ldc_w instead of ldc 1493 u_char inst_buffer[4]; // max instruction size is 4 bytes 1494 bcp = (address)inst_buffer; 1495 // construct new instruction sequence 1496 *bcp = Bytecodes::_ldc_w; 1497 bcp++; 1498 // Rewriter::rewrite_method() does not rewrite ldc -> ldc_w. 1499 // See comment below for difference between put_Java_u2() 1500 // and put_native_u2(). 1501 Bytes::put_Java_u2(bcp, new_index); 1502 1503 Relocator rc(method, NULL /* no RelocatorListener needed */); 1504 methodHandle m; 1505 { 1506 Pause_No_Safepoint_Verifier pnsv(&nsv); 1507 1508 // ldc is 2 bytes and ldc_w is 3 bytes 1509 m = rc.insert_space_at(bci, 3, inst_buffer, THREAD); 1510 if (m.is_null() || HAS_PENDING_EXCEPTION) { 1511 guarantee(false, "insert_space_at() failed"); 1512 } 1513 } 1514 1515 // return the new method so that the caller can update 1516 // the containing class 1517 *new_method_p = method = m; 1518 // switch our bytecode processing loop from the old method 1519 // to the new method 1520 code_base = method->code_base(); 1521 code_length = method->code_size(); 1522 bcp = code_base + bci; 1523 c = (Bytecodes::Code)(*bcp); 1524 bc_length = Bytecodes::length_for(c); 1525 assert(bc_length != 0, "sanity check"); 1526 } // end we need ldc_w instead of ldc 1527 } // end if there is a mapped index 1528 } break; 1529 1530 // these bytecodes have a two-byte constant pool index 1531 case Bytecodes::_anewarray : // fall through 1532 case Bytecodes::_checkcast : // fall through 1533 case Bytecodes::_getfield : // fall through 1534 case Bytecodes::_getstatic : // fall through 1535 case Bytecodes::_instanceof : // fall through 1536 case Bytecodes::_invokeinterface: // fall through 1537 case Bytecodes::_invokespecial : // fall through 1538 case Bytecodes::_invokestatic : // fall through 1539 case Bytecodes::_invokevirtual : // fall through 1540 case Bytecodes::_ldc_w : // fall through 1541 case Bytecodes::_ldc2_w : // fall through 1542 case Bytecodes::_multianewarray : // fall through 1543 case Bytecodes::_new : // fall through 1544 case Bytecodes::_putfield : // fall through 1545 case Bytecodes::_putstatic : 1546 { 1547 address p = bcp + 1; 1548 int cp_index = Bytes::get_Java_u2(p); 1549 int new_index = find_new_index(cp_index); 1550 if (new_index != 0) { 1551 // the original index is mapped so update w/ new value 1552 RC_TRACE_WITH_THREAD(0x00080000, THREAD, 1553 ("%s@" INTPTR_FORMAT " old=%d, new=%d", Bytecodes::name(c), 1554 bcp, cp_index, new_index)); 1555 // Rewriter::rewrite_method() uses put_native_u2() in this 1556 // situation because it is reusing the constant pool index 1557 // location for a native index into the constantPoolCache. 1558 // Since we are updating the constant pool index prior to 1559 // verification and constantPoolCache initialization, we 1560 // need to keep the new index in Java byte order. 1561 Bytes::put_Java_u2(p, new_index); 1562 } 1563 } break; 1564 } 1565 } // end for each bytecode 1566 } // end rewrite_cp_refs_in_method() 1567 1568 1569 // Rewrite constant pool references in the class_annotations field. 1570 bool VM_RedefineClasses::rewrite_cp_refs_in_class_annotations( 1571 instanceKlassHandle scratch_class, TRAPS) { 1572 1573 typeArrayHandle class_annotations(THREAD, 1574 scratch_class->class_annotations()); 1575 if (class_annotations.is_null() || class_annotations->length() == 0) { 1576 // no class_annotations so nothing to do 1577 return true; 1578 } 1579 1580 RC_TRACE_WITH_THREAD(0x02000000, THREAD, 1581 ("class_annotations length=%d", class_annotations->length())); 1582 1583 int byte_i = 0; // byte index into class_annotations 1584 return rewrite_cp_refs_in_annotations_typeArray(class_annotations, byte_i, 1585 THREAD); 1586 } 1587 1588 1589 // Rewrite constant pool references in an annotations typeArray. This 1590 // "structure" is adapted from the RuntimeVisibleAnnotations_attribute 1591 // that is described in section 4.8.15 of the 2nd-edition of the VM spec: 1592 // 1593 // annotations_typeArray { 1594 // u2 num_annotations; 1595 // annotation annotations[num_annotations]; 1596 // } 1597 // 1598 bool VM_RedefineClasses::rewrite_cp_refs_in_annotations_typeArray( 1599 typeArrayHandle annotations_typeArray, int &byte_i_ref, TRAPS) { 1600 1601 if ((byte_i_ref + 2) > annotations_typeArray->length()) { 1602 // not enough room for num_annotations field 1603 RC_TRACE_WITH_THREAD(0x02000000, THREAD, 1604 ("length() is too small for num_annotations field")); 1605 return false; 1606 } 1607 1608 u2 num_annotations = Bytes::get_Java_u2((address) 1609 annotations_typeArray->byte_at_addr(byte_i_ref)); 1610 byte_i_ref += 2; 1611 1612 RC_TRACE_WITH_THREAD(0x02000000, THREAD, 1613 ("num_annotations=%d", num_annotations)); 1614 1615 int calc_num_annotations = 0; 1616 for (; calc_num_annotations < num_annotations; calc_num_annotations++) { 1617 if (!rewrite_cp_refs_in_annotation_struct(annotations_typeArray, 1618 byte_i_ref, THREAD)) { 1619 RC_TRACE_WITH_THREAD(0x02000000, THREAD, 1620 ("bad annotation_struct at %d", calc_num_annotations)); 1621 // propagate failure back to caller 1622 return false; 1623 } 1624 } 1625 assert(num_annotations == calc_num_annotations, "sanity check"); 1626 1627 return true; 1628 } // end rewrite_cp_refs_in_annotations_typeArray() 1629 1630 1631 // Rewrite constant pool references in the annotation struct portion of 1632 // an annotations_typeArray. This "structure" is from section 4.8.15 of 1633 // the 2nd-edition of the VM spec: 1634 // 1635 // struct annotation { 1636 // u2 type_index; 1637 // u2 num_element_value_pairs; 1638 // { 1639 // u2 element_name_index; 1640 // element_value value; 1641 // } element_value_pairs[num_element_value_pairs]; 1642 // } 1643 // 1644 bool VM_RedefineClasses::rewrite_cp_refs_in_annotation_struct( 1645 typeArrayHandle annotations_typeArray, int &byte_i_ref, TRAPS) { 1646 if ((byte_i_ref + 2 + 2) > annotations_typeArray->length()) { 1647 // not enough room for smallest annotation_struct 1648 RC_TRACE_WITH_THREAD(0x02000000, THREAD, 1649 ("length() is too small for annotation_struct")); 1650 return false; 1651 } 1652 1653 u2 type_index = rewrite_cp_ref_in_annotation_data(annotations_typeArray, 1654 byte_i_ref, "mapped old type_index=%d", THREAD); 1655 1656 u2 num_element_value_pairs = Bytes::get_Java_u2((address) 1657 annotations_typeArray->byte_at_addr( 1658 byte_i_ref)); 1659 byte_i_ref += 2; 1660 1661 RC_TRACE_WITH_THREAD(0x02000000, THREAD, 1662 ("type_index=%d num_element_value_pairs=%d", type_index, 1663 num_element_value_pairs)); 1664 1665 int calc_num_element_value_pairs = 0; 1666 for (; calc_num_element_value_pairs < num_element_value_pairs; 1667 calc_num_element_value_pairs++) { 1668 if ((byte_i_ref + 2) > annotations_typeArray->length()) { 1669 // not enough room for another element_name_index, let alone 1670 // the rest of another component 1671 RC_TRACE_WITH_THREAD(0x02000000, THREAD, 1672 ("length() is too small for element_name_index")); 1673 return false; 1674 } 1675 1676 u2 element_name_index = rewrite_cp_ref_in_annotation_data( 1677 annotations_typeArray, byte_i_ref, 1678 "mapped old element_name_index=%d", THREAD); 1679 1680 RC_TRACE_WITH_THREAD(0x02000000, THREAD, 1681 ("element_name_index=%d", element_name_index)); 1682 1683 if (!rewrite_cp_refs_in_element_value(annotations_typeArray, 1684 byte_i_ref, THREAD)) { 1685 RC_TRACE_WITH_THREAD(0x02000000, THREAD, 1686 ("bad element_value at %d", calc_num_element_value_pairs)); 1687 // propagate failure back to caller 1688 return false; 1689 } 1690 } // end for each component 1691 assert(num_element_value_pairs == calc_num_element_value_pairs, 1692 "sanity check"); 1693 1694 return true; 1695 } // end rewrite_cp_refs_in_annotation_struct() 1696 1697 1698 // Rewrite a constant pool reference at the current position in 1699 // annotations_typeArray if needed. Returns the original constant 1700 // pool reference if a rewrite was not needed or the new constant 1701 // pool reference if a rewrite was needed. 1702 u2 VM_RedefineClasses::rewrite_cp_ref_in_annotation_data( 1703 typeArrayHandle annotations_typeArray, int &byte_i_ref, 1704 const char * trace_mesg, TRAPS) { 1705 1706 address cp_index_addr = (address) 1707 annotations_typeArray->byte_at_addr(byte_i_ref); 1708 u2 old_cp_index = Bytes::get_Java_u2(cp_index_addr); 1709 u2 new_cp_index = find_new_index(old_cp_index); 1710 if (new_cp_index != 0) { 1711 RC_TRACE_WITH_THREAD(0x02000000, THREAD, (trace_mesg, old_cp_index)); 1712 Bytes::put_Java_u2(cp_index_addr, new_cp_index); 1713 old_cp_index = new_cp_index; 1714 } 1715 byte_i_ref += 2; 1716 return old_cp_index; 1717 } 1718 1719 1720 // Rewrite constant pool references in the element_value portion of an 1721 // annotations_typeArray. This "structure" is from section 4.8.15.1 of 1722 // the 2nd-edition of the VM spec: 1723 // 1724 // struct element_value { 1725 // u1 tag; 1726 // union { 1727 // u2 const_value_index; 1728 // { 1729 // u2 type_name_index; 1730 // u2 const_name_index; 1731 // } enum_const_value; 1732 // u2 class_info_index; 1733 // annotation annotation_value; 1734 // struct { 1735 // u2 num_values; 1736 // element_value values[num_values]; 1737 // } array_value; 1738 // } value; 1739 // } 1740 // 1741 bool VM_RedefineClasses::rewrite_cp_refs_in_element_value( 1742 typeArrayHandle annotations_typeArray, int &byte_i_ref, TRAPS) { 1743 1744 if ((byte_i_ref + 1) > annotations_typeArray->length()) { 1745 // not enough room for a tag let alone the rest of an element_value 1746 RC_TRACE_WITH_THREAD(0x02000000, THREAD, 1747 ("length() is too small for a tag")); 1748 return false; 1749 } 1750 1751 u1 tag = annotations_typeArray->byte_at(byte_i_ref); 1752 byte_i_ref++; 1753 RC_TRACE_WITH_THREAD(0x02000000, THREAD, ("tag='%c'", tag)); 1754 1755 switch (tag) { 1756 // These BaseType tag values are from Table 4.2 in VM spec: 1757 case 'B': // byte 1758 case 'C': // char 1759 case 'D': // double 1760 case 'F': // float 1761 case 'I': // int 1762 case 'J': // long 1763 case 'S': // short 1764 case 'Z': // boolean 1765 1766 // The remaining tag values are from Table 4.8 in the 2nd-edition of 1767 // the VM spec: 1768 case 's': 1769 { 1770 // For the above tag values (including the BaseType values), 1771 // value.const_value_index is right union field. 1772 1773 if ((byte_i_ref + 2) > annotations_typeArray->length()) { 1774 // not enough room for a const_value_index 1775 RC_TRACE_WITH_THREAD(0x02000000, THREAD, 1776 ("length() is too small for a const_value_index")); 1777 return false; 1778 } 1779 1780 u2 const_value_index = rewrite_cp_ref_in_annotation_data( 1781 annotations_typeArray, byte_i_ref, 1782 "mapped old const_value_index=%d", THREAD); 1783 1784 RC_TRACE_WITH_THREAD(0x02000000, THREAD, 1785 ("const_value_index=%d", const_value_index)); 1786 } break; 1787 1788 case 'e': 1789 { 1790 // for the above tag value, value.enum_const_value is right union field 1791 1792 if ((byte_i_ref + 4) > annotations_typeArray->length()) { 1793 // not enough room for a enum_const_value 1794 RC_TRACE_WITH_THREAD(0x02000000, THREAD, 1795 ("length() is too small for a enum_const_value")); 1796 return false; 1797 } 1798 1799 u2 type_name_index = rewrite_cp_ref_in_annotation_data( 1800 annotations_typeArray, byte_i_ref, 1801 "mapped old type_name_index=%d", THREAD); 1802 1803 u2 const_name_index = rewrite_cp_ref_in_annotation_data( 1804 annotations_typeArray, byte_i_ref, 1805 "mapped old const_name_index=%d", THREAD); 1806 1807 RC_TRACE_WITH_THREAD(0x02000000, THREAD, 1808 ("type_name_index=%d const_name_index=%d", type_name_index, 1809 const_name_index)); 1810 } break; 1811 1812 case 'c': 1813 { 1814 // for the above tag value, value.class_info_index is right union field 1815 1816 if ((byte_i_ref + 2) > annotations_typeArray->length()) { 1817 // not enough room for a class_info_index 1818 RC_TRACE_WITH_THREAD(0x02000000, THREAD, 1819 ("length() is too small for a class_info_index")); 1820 return false; 1821 } 1822 1823 u2 class_info_index = rewrite_cp_ref_in_annotation_data( 1824 annotations_typeArray, byte_i_ref, 1825 "mapped old class_info_index=%d", THREAD); 1826 1827 RC_TRACE_WITH_THREAD(0x02000000, THREAD, 1828 ("class_info_index=%d", class_info_index)); 1829 } break; 1830 1831 case '@': 1832 // For the above tag value, value.attr_value is the right union 1833 // field. This is a nested annotation. 1834 if (!rewrite_cp_refs_in_annotation_struct(annotations_typeArray, 1835 byte_i_ref, THREAD)) { 1836 // propagate failure back to caller 1837 return false; 1838 } 1839 break; 1840 1841 case '[': 1842 { 1843 if ((byte_i_ref + 2) > annotations_typeArray->length()) { 1844 // not enough room for a num_values field 1845 RC_TRACE_WITH_THREAD(0x02000000, THREAD, 1846 ("length() is too small for a num_values field")); 1847 return false; 1848 } 1849 1850 // For the above tag value, value.array_value is the right union 1851 // field. This is an array of nested element_value. 1852 u2 num_values = Bytes::get_Java_u2((address) 1853 annotations_typeArray->byte_at_addr(byte_i_ref)); 1854 byte_i_ref += 2; 1855 RC_TRACE_WITH_THREAD(0x02000000, THREAD, ("num_values=%d", num_values)); 1856 1857 int calc_num_values = 0; 1858 for (; calc_num_values < num_values; calc_num_values++) { 1859 if (!rewrite_cp_refs_in_element_value( 1860 annotations_typeArray, byte_i_ref, THREAD)) { 1861 RC_TRACE_WITH_THREAD(0x02000000, THREAD, 1862 ("bad nested element_value at %d", calc_num_values)); 1863 // propagate failure back to caller 1864 return false; 1865 } 1866 } 1867 assert(num_values == calc_num_values, "sanity check"); 1868 } break; 1869 1870 default: 1871 RC_TRACE_WITH_THREAD(0x02000000, THREAD, ("bad tag=0x%x", tag)); 1872 return false; 1873 } // end decode tag field 1874 1875 return true; 1876 } // end rewrite_cp_refs_in_element_value() 1877 1878 1879 // Rewrite constant pool references in a fields_annotations field. 1880 bool VM_RedefineClasses::rewrite_cp_refs_in_fields_annotations( 1881 instanceKlassHandle scratch_class, TRAPS) { 1882 1883 objArrayHandle fields_annotations(THREAD, 1884 scratch_class->fields_annotations()); 1885 1886 if (fields_annotations.is_null() || fields_annotations->length() == 0) { 1887 // no fields_annotations so nothing to do 1888 return true; 1889 } 1890 1891 RC_TRACE_WITH_THREAD(0x02000000, THREAD, 1892 ("fields_annotations length=%d", fields_annotations->length())); 1893 1894 for (int i = 0; i < fields_annotations->length(); i++) { 1895 typeArrayHandle field_annotations(THREAD, 1896 (typeArrayOop)fields_annotations->obj_at(i)); 1897 if (field_annotations.is_null() || field_annotations->length() == 0) { 1898 // this field does not have any annotations so skip it 1899 continue; 1900 } 1901 1902 int byte_i = 0; // byte index into field_annotations 1903 if (!rewrite_cp_refs_in_annotations_typeArray(field_annotations, byte_i, 1904 THREAD)) { 1905 RC_TRACE_WITH_THREAD(0x02000000, THREAD, 1906 ("bad field_annotations at %d", i)); 1907 // propagate failure back to caller 1908 return false; 1909 } 1910 } 1911 1912 return true; 1913 } // end rewrite_cp_refs_in_fields_annotations() 1914 1915 1916 // Rewrite constant pool references in a methods_annotations field. 1917 bool VM_RedefineClasses::rewrite_cp_refs_in_methods_annotations( 1918 instanceKlassHandle scratch_class, TRAPS) { 1919 1920 objArrayHandle methods_annotations(THREAD, 1921 scratch_class->methods_annotations()); 1922 1923 if (methods_annotations.is_null() || methods_annotations->length() == 0) { 1924 // no methods_annotations so nothing to do 1925 return true; 1926 } 1927 1928 RC_TRACE_WITH_THREAD(0x02000000, THREAD, 1929 ("methods_annotations length=%d", methods_annotations->length())); 1930 1931 for (int i = 0; i < methods_annotations->length(); i++) { 1932 typeArrayHandle method_annotations(THREAD, 1933 (typeArrayOop)methods_annotations->obj_at(i)); 1934 if (method_annotations.is_null() || method_annotations->length() == 0) { 1935 // this method does not have any annotations so skip it 1936 continue; 1937 } 1938 1939 int byte_i = 0; // byte index into method_annotations 1940 if (!rewrite_cp_refs_in_annotations_typeArray(method_annotations, byte_i, 1941 THREAD)) { 1942 RC_TRACE_WITH_THREAD(0x02000000, THREAD, 1943 ("bad method_annotations at %d", i)); 1944 // propagate failure back to caller 1945 return false; 1946 } 1947 } 1948 1949 return true; 1950 } // end rewrite_cp_refs_in_methods_annotations() 1951 1952 1953 // Rewrite constant pool references in a methods_parameter_annotations 1954 // field. This "structure" is adapted from the 1955 // RuntimeVisibleParameterAnnotations_attribute described in section 1956 // 4.8.17 of the 2nd-edition of the VM spec: 1957 // 1958 // methods_parameter_annotations_typeArray { 1959 // u1 num_parameters; 1960 // { 1961 // u2 num_annotations; 1962 // annotation annotations[num_annotations]; 1963 // } parameter_annotations[num_parameters]; 1964 // } 1965 // 1966 bool VM_RedefineClasses::rewrite_cp_refs_in_methods_parameter_annotations( 1967 instanceKlassHandle scratch_class, TRAPS) { 1968 1969 objArrayHandle methods_parameter_annotations(THREAD, 1970 scratch_class->methods_parameter_annotations()); 1971 1972 if (methods_parameter_annotations.is_null() 1973 || methods_parameter_annotations->length() == 0) { 1974 // no methods_parameter_annotations so nothing to do 1975 return true; 1976 } 1977 1978 RC_TRACE_WITH_THREAD(0x02000000, THREAD, 1979 ("methods_parameter_annotations length=%d", 1980 methods_parameter_annotations->length())); 1981 1982 for (int i = 0; i < methods_parameter_annotations->length(); i++) { 1983 typeArrayHandle method_parameter_annotations(THREAD, 1984 (typeArrayOop)methods_parameter_annotations->obj_at(i)); 1985 if (method_parameter_annotations.is_null() 1986 || method_parameter_annotations->length() == 0) { 1987 // this method does not have any parameter annotations so skip it 1988 continue; 1989 } 1990 1991 if (method_parameter_annotations->length() < 1) { 1992 // not enough room for a num_parameters field 1993 RC_TRACE_WITH_THREAD(0x02000000, THREAD, 1994 ("length() is too small for a num_parameters field at %d", i)); 1995 return false; 1996 } 1997 1998 int byte_i = 0; // byte index into method_parameter_annotations 1999 2000 u1 num_parameters = method_parameter_annotations->byte_at(byte_i); 2001 byte_i++; 2002 2003 RC_TRACE_WITH_THREAD(0x02000000, THREAD, 2004 ("num_parameters=%d", num_parameters)); 2005 2006 int calc_num_parameters = 0; 2007 for (; calc_num_parameters < num_parameters; calc_num_parameters++) { 2008 if (!rewrite_cp_refs_in_annotations_typeArray( 2009 method_parameter_annotations, byte_i, THREAD)) { 2010 RC_TRACE_WITH_THREAD(0x02000000, THREAD, 2011 ("bad method_parameter_annotations at %d", calc_num_parameters)); 2012 // propagate failure back to caller 2013 return false; 2014 } 2015 } 2016 assert(num_parameters == calc_num_parameters, "sanity check"); 2017 } 2018 2019 return true; 2020 } // end rewrite_cp_refs_in_methods_parameter_annotations() 2021 2022 2023 // Rewrite constant pool references in a methods_default_annotations 2024 // field. This "structure" is adapted from the AnnotationDefault_attribute 2025 // that is described in section 4.8.19 of the 2nd-edition of the VM spec: 2026 // 2027 // methods_default_annotations_typeArray { 2028 // element_value default_value; 2029 // } 2030 // 2031 bool VM_RedefineClasses::rewrite_cp_refs_in_methods_default_annotations( 2032 instanceKlassHandle scratch_class, TRAPS) { 2033 2034 objArrayHandle methods_default_annotations(THREAD, 2035 scratch_class->methods_default_annotations()); 2036 2037 if (methods_default_annotations.is_null() 2038 || methods_default_annotations->length() == 0) { 2039 // no methods_default_annotations so nothing to do 2040 return true; 2041 } 2042 2043 RC_TRACE_WITH_THREAD(0x02000000, THREAD, 2044 ("methods_default_annotations length=%d", 2045 methods_default_annotations->length())); 2046 2047 for (int i = 0; i < methods_default_annotations->length(); i++) { 2048 typeArrayHandle method_default_annotations(THREAD, 2049 (typeArrayOop)methods_default_annotations->obj_at(i)); 2050 if (method_default_annotations.is_null() 2051 || method_default_annotations->length() == 0) { 2052 // this method does not have any default annotations so skip it 2053 continue; 2054 } 2055 2056 int byte_i = 0; // byte index into method_default_annotations 2057 2058 if (!rewrite_cp_refs_in_element_value( 2059 method_default_annotations, byte_i, THREAD)) { 2060 RC_TRACE_WITH_THREAD(0x02000000, THREAD, 2061 ("bad default element_value at %d", i)); 2062 // propagate failure back to caller 2063 return false; 2064 } 2065 } 2066 2067 return true; 2068 } // end rewrite_cp_refs_in_methods_default_annotations() 2069 2070 2071 // Rewrite constant pool references in the method's stackmap table. 2072 // These "structures" are adapted from the StackMapTable_attribute that 2073 // is described in section 4.8.4 of the 6.0 version of the VM spec 2074 // (dated 2005.10.26): 2075 // file:///net/quincunx.sfbay/export/gbracha/ClassFile-Java6.pdf 2076 // 2077 // stack_map { 2078 // u2 number_of_entries; 2079 // stack_map_frame entries[number_of_entries]; 2080 // } 2081 // 2082 void VM_RedefineClasses::rewrite_cp_refs_in_stack_map_table( 2083 methodHandle method, TRAPS) { 2084 2085 if (!method->has_stackmap_table()) { 2086 return; 2087 } 2088 2089 typeArrayOop stackmap_data = method->stackmap_data(); 2090 address stackmap_p = (address)stackmap_data->byte_at_addr(0); 2091 address stackmap_end = stackmap_p + stackmap_data->length(); 2092 2093 assert(stackmap_p + 2 <= stackmap_end, "no room for number_of_entries"); 2094 u2 number_of_entries = Bytes::get_Java_u2(stackmap_p); 2095 stackmap_p += 2; 2096 2097 RC_TRACE_WITH_THREAD(0x04000000, THREAD, 2098 ("number_of_entries=%u", number_of_entries)); 2099 2100 // walk through each stack_map_frame 2101 u2 calc_number_of_entries = 0; 2102 for (; calc_number_of_entries < number_of_entries; calc_number_of_entries++) { 2103 // The stack_map_frame structure is a u1 frame_type followed by 2104 // 0 or more bytes of data: 2105 // 2106 // union stack_map_frame { 2107 // same_frame; 2108 // same_locals_1_stack_item_frame; 2109 // same_locals_1_stack_item_frame_extended; 2110 // chop_frame; 2111 // same_frame_extended; 2112 // append_frame; 2113 // full_frame; 2114 // } 2115 2116 assert(stackmap_p + 1 <= stackmap_end, "no room for frame_type"); 2117 // The Linux compiler does not like frame_type to be u1 or u2. It 2118 // issues the following warning for the first if-statement below: 2119 // 2120 // "warning: comparison is always true due to limited range of data type" 2121 // 2122 u4 frame_type = *stackmap_p; 2123 stackmap_p++; 2124 2125 // same_frame { 2126 // u1 frame_type = SAME; /* 0-63 */ 2127 // } 2128 if (frame_type >= 0 && frame_type <= 63) { 2129 // nothing more to do for same_frame 2130 } 2131 2132 // same_locals_1_stack_item_frame { 2133 // u1 frame_type = SAME_LOCALS_1_STACK_ITEM; /* 64-127 */ 2134 // verification_type_info stack[1]; 2135 // } 2136 else if (frame_type >= 64 && frame_type <= 127) { 2137 rewrite_cp_refs_in_verification_type_info(stackmap_p, stackmap_end, 2138 calc_number_of_entries, frame_type, THREAD); 2139 } 2140 2141 // reserved for future use 2142 else if (frame_type >= 128 && frame_type <= 246) { 2143 // nothing more to do for reserved frame_types 2144 } 2145 2146 // same_locals_1_stack_item_frame_extended { 2147 // u1 frame_type = SAME_LOCALS_1_STACK_ITEM_EXTENDED; /* 247 */ 2148 // u2 offset_delta; 2149 // verification_type_info stack[1]; 2150 // } 2151 else if (frame_type == 247) { 2152 stackmap_p += 2; 2153 rewrite_cp_refs_in_verification_type_info(stackmap_p, stackmap_end, 2154 calc_number_of_entries, frame_type, THREAD); 2155 } 2156 2157 // chop_frame { 2158 // u1 frame_type = CHOP; /* 248-250 */ 2159 // u2 offset_delta; 2160 // } 2161 else if (frame_type >= 248 && frame_type <= 250) { 2162 stackmap_p += 2; 2163 } 2164 2165 // same_frame_extended { 2166 // u1 frame_type = SAME_FRAME_EXTENDED; /* 251*/ 2167 // u2 offset_delta; 2168 // } 2169 else if (frame_type == 251) { 2170 stackmap_p += 2; 2171 } 2172 2173 // append_frame { 2174 // u1 frame_type = APPEND; /* 252-254 */ 2175 // u2 offset_delta; 2176 // verification_type_info locals[frame_type - 251]; 2177 // } 2178 else if (frame_type >= 252 && frame_type <= 254) { 2179 assert(stackmap_p + 2 <= stackmap_end, 2180 "no room for offset_delta"); 2181 stackmap_p += 2; 2182 u1 len = frame_type - 251; 2183 for (u1 i = 0; i < len; i++) { 2184 rewrite_cp_refs_in_verification_type_info(stackmap_p, stackmap_end, 2185 calc_number_of_entries, frame_type, THREAD); 2186 } 2187 } 2188 2189 // full_frame { 2190 // u1 frame_type = FULL_FRAME; /* 255 */ 2191 // u2 offset_delta; 2192 // u2 number_of_locals; 2193 // verification_type_info locals[number_of_locals]; 2194 // u2 number_of_stack_items; 2195 // verification_type_info stack[number_of_stack_items]; 2196 // } 2197 else if (frame_type == 255) { 2198 assert(stackmap_p + 2 + 2 <= stackmap_end, 2199 "no room for smallest full_frame"); 2200 stackmap_p += 2; 2201 2202 u2 number_of_locals = Bytes::get_Java_u2(stackmap_p); 2203 stackmap_p += 2; 2204 2205 for (u2 locals_i = 0; locals_i < number_of_locals; locals_i++) { 2206 rewrite_cp_refs_in_verification_type_info(stackmap_p, stackmap_end, 2207 calc_number_of_entries, frame_type, THREAD); 2208 } 2209 2210 // Use the largest size for the number_of_stack_items, but only get 2211 // the right number of bytes. 2212 u2 number_of_stack_items = Bytes::get_Java_u2(stackmap_p); 2213 stackmap_p += 2; 2214 2215 for (u2 stack_i = 0; stack_i < number_of_stack_items; stack_i++) { 2216 rewrite_cp_refs_in_verification_type_info(stackmap_p, stackmap_end, 2217 calc_number_of_entries, frame_type, THREAD); 2218 } 2219 } 2220 } // end while there is a stack_map_frame 2221 assert(number_of_entries == calc_number_of_entries, "sanity check"); 2222 } // end rewrite_cp_refs_in_stack_map_table() 2223 2224 2225 // Rewrite constant pool references in the verification type info 2226 // portion of the method's stackmap table. These "structures" are 2227 // adapted from the StackMapTable_attribute that is described in 2228 // section 4.8.4 of the 6.0 version of the VM spec (dated 2005.10.26): 2229 // file:///net/quincunx.sfbay/export/gbracha/ClassFile-Java6.pdf 2230 // 2231 // The verification_type_info structure is a u1 tag followed by 0 or 2232 // more bytes of data: 2233 // 2234 // union verification_type_info { 2235 // Top_variable_info; 2236 // Integer_variable_info; 2237 // Float_variable_info; 2238 // Long_variable_info; 2239 // Double_variable_info; 2240 // Null_variable_info; 2241 // UninitializedThis_variable_info; 2242 // Object_variable_info; 2243 // Uninitialized_variable_info; 2244 // } 2245 // 2246 void VM_RedefineClasses::rewrite_cp_refs_in_verification_type_info( 2247 address& stackmap_p_ref, address stackmap_end, u2 frame_i, 2248 u1 frame_type, TRAPS) { 2249 2250 assert(stackmap_p_ref + 1 <= stackmap_end, "no room for tag"); 2251 u1 tag = *stackmap_p_ref; 2252 stackmap_p_ref++; 2253 2254 switch (tag) { 2255 // Top_variable_info { 2256 // u1 tag = ITEM_Top; /* 0 */ 2257 // } 2258 // verificationType.hpp has zero as ITEM_Bogus instead of ITEM_Top 2259 case 0: // fall through 2260 2261 // Integer_variable_info { 2262 // u1 tag = ITEM_Integer; /* 1 */ 2263 // } 2264 case ITEM_Integer: // fall through 2265 2266 // Float_variable_info { 2267 // u1 tag = ITEM_Float; /* 2 */ 2268 // } 2269 case ITEM_Float: // fall through 2270 2271 // Double_variable_info { 2272 // u1 tag = ITEM_Double; /* 3 */ 2273 // } 2274 case ITEM_Double: // fall through 2275 2276 // Long_variable_info { 2277 // u1 tag = ITEM_Long; /* 4 */ 2278 // } 2279 case ITEM_Long: // fall through 2280 2281 // Null_variable_info { 2282 // u1 tag = ITEM_Null; /* 5 */ 2283 // } 2284 case ITEM_Null: // fall through 2285 2286 // UninitializedThis_variable_info { 2287 // u1 tag = ITEM_UninitializedThis; /* 6 */ 2288 // } 2289 case ITEM_UninitializedThis: 2290 // nothing more to do for the above tag types 2291 break; 2292 2293 // Object_variable_info { 2294 // u1 tag = ITEM_Object; /* 7 */ 2295 // u2 cpool_index; 2296 // } 2297 case ITEM_Object: 2298 { 2299 assert(stackmap_p_ref + 2 <= stackmap_end, "no room for cpool_index"); 2300 u2 cpool_index = Bytes::get_Java_u2(stackmap_p_ref); 2301 u2 new_cp_index = find_new_index(cpool_index); 2302 if (new_cp_index != 0) { 2303 RC_TRACE_WITH_THREAD(0x04000000, THREAD, 2304 ("mapped old cpool_index=%d", cpool_index)); 2305 Bytes::put_Java_u2(stackmap_p_ref, new_cp_index); 2306 cpool_index = new_cp_index; 2307 } 2308 stackmap_p_ref += 2; 2309 2310 RC_TRACE_WITH_THREAD(0x04000000, THREAD, 2311 ("frame_i=%u, frame_type=%u, cpool_index=%d", frame_i, 2312 frame_type, cpool_index)); 2313 } break; 2314 2315 // Uninitialized_variable_info { 2316 // u1 tag = ITEM_Uninitialized; /* 8 */ 2317 // u2 offset; 2318 // } 2319 case ITEM_Uninitialized: 2320 assert(stackmap_p_ref + 2 <= stackmap_end, "no room for offset"); 2321 stackmap_p_ref += 2; 2322 break; 2323 2324 default: 2325 RC_TRACE_WITH_THREAD(0x04000000, THREAD, 2326 ("frame_i=%u, frame_type=%u, bad tag=0x%x", frame_i, frame_type, tag)); 2327 ShouldNotReachHere(); 2328 break; 2329 } // end switch (tag) 2330 } // end rewrite_cp_refs_in_verification_type_info() 2331 2332 2333 // Change the constant pool associated with klass scratch_class to 2334 // scratch_cp. If shrink is true, then scratch_cp_length elements 2335 // are copied from scratch_cp to a smaller constant pool and the 2336 // smaller constant pool is associated with scratch_class. 2337 void VM_RedefineClasses::set_new_constant_pool( 2338 instanceKlassHandle scratch_class, constantPoolHandle scratch_cp, 2339 int scratch_cp_length, bool shrink, TRAPS) { 2340 assert(!shrink || scratch_cp->length() >= scratch_cp_length, "sanity check"); 2341 2342 if (shrink) { 2343 // scratch_cp is a merged constant pool and has enough space for a 2344 // worst case merge situation. We want to associate the minimum 2345 // sized constant pool with the klass to save space. 2346 constantPoolHandle smaller_cp(THREAD, 2347 oopFactory::new_constantPool(scratch_cp_length, 2348 oopDesc::IsUnsafeConc, 2349 THREAD)); 2350 // preserve orig_length() value in the smaller copy 2351 int orig_length = scratch_cp->orig_length(); 2352 assert(orig_length != 0, "sanity check"); 2353 smaller_cp->set_orig_length(orig_length); 2354 scratch_cp->copy_cp_to(1, scratch_cp_length - 1, smaller_cp, 1, THREAD); 2355 scratch_cp = smaller_cp; 2356 smaller_cp()->set_is_conc_safe(true); 2357 } 2358 2359 // attach new constant pool to klass 2360 scratch_cp->set_pool_holder(scratch_class()); 2361 2362 // attach klass to new constant pool 2363 scratch_class->set_constants(scratch_cp()); 2364 2365 int i; // for portability 2366 2367 // update each field in klass to use new constant pool indices as needed 2368 for (JavaFieldStream fs(scratch_class); !fs.done(); fs.next()) { 2369 jshort cur_index = fs.name_index(); 2370 jshort new_index = find_new_index(cur_index); 2371 if (new_index != 0) { 2372 RC_TRACE_WITH_THREAD(0x00080000, THREAD, 2373 ("field-name_index change: %d to %d", cur_index, new_index)); 2374 fs.set_name_index(new_index); 2375 } 2376 cur_index = fs.signature_index(); 2377 new_index = find_new_index(cur_index); 2378 if (new_index != 0) { 2379 RC_TRACE_WITH_THREAD(0x00080000, THREAD, 2380 ("field-signature_index change: %d to %d", cur_index, new_index)); 2381 fs.set_signature_index(new_index); 2382 } 2383 cur_index = fs.initval_index(); 2384 new_index = find_new_index(cur_index); 2385 if (new_index != 0) { 2386 RC_TRACE_WITH_THREAD(0x00080000, THREAD, 2387 ("field-initval_index change: %d to %d", cur_index, new_index)); 2388 fs.set_initval_index(new_index); 2389 } 2390 cur_index = fs.generic_signature_index(); 2391 new_index = find_new_index(cur_index); 2392 if (new_index != 0) { 2393 RC_TRACE_WITH_THREAD(0x00080000, THREAD, 2394 ("field-generic_signature change: %d to %d", cur_index, new_index)); 2395 fs.set_generic_signature_index(new_index); 2396 } 2397 } // end for each field 2398 2399 // Update constant pool indices in the inner classes info to use 2400 // new constant indices as needed. The inner classes info is a 2401 // quadruple: 2402 // (inner_class_info, outer_class_info, inner_name, inner_access_flags) 2403 InnerClassesIterator iter(scratch_class); 2404 for (; !iter.done(); iter.next()) { 2405 int cur_index = iter.inner_class_info_index(); 2406 if (cur_index == 0) { 2407 continue; // JVM spec. allows null inner class refs so skip it 2408 } 2409 int new_index = find_new_index(cur_index); 2410 if (new_index != 0) { 2411 RC_TRACE_WITH_THREAD(0x00080000, THREAD, 2412 ("inner_class_info change: %d to %d", cur_index, new_index)); 2413 iter.set_inner_class_info_index(new_index); 2414 } 2415 cur_index = iter.outer_class_info_index(); 2416 new_index = find_new_index(cur_index); 2417 if (new_index != 0) { 2418 RC_TRACE_WITH_THREAD(0x00080000, THREAD, 2419 ("outer_class_info change: %d to %d", cur_index, new_index)); 2420 iter.set_outer_class_info_index(new_index); 2421 } 2422 cur_index = iter.inner_name_index(); 2423 new_index = find_new_index(cur_index); 2424 if (new_index != 0) { 2425 RC_TRACE_WITH_THREAD(0x00080000, THREAD, 2426 ("inner_name change: %d to %d", cur_index, new_index)); 2427 iter.set_inner_name_index(new_index); 2428 } 2429 } // end for each inner class 2430 2431 // Attach each method in klass to the new constant pool and update 2432 // to use new constant pool indices as needed: 2433 objArrayHandle methods(THREAD, scratch_class->methods()); 2434 for (i = methods->length() - 1; i >= 0; i--) { 2435 methodHandle method(THREAD, (methodOop)methods->obj_at(i)); 2436 method->set_constants(scratch_cp()); 2437 2438 int new_index = find_new_index(method->name_index()); 2439 if (new_index != 0) { 2440 RC_TRACE_WITH_THREAD(0x00080000, THREAD, 2441 ("method-name_index change: %d to %d", method->name_index(), 2442 new_index)); 2443 method->set_name_index(new_index); 2444 } 2445 new_index = find_new_index(method->signature_index()); 2446 if (new_index != 0) { 2447 RC_TRACE_WITH_THREAD(0x00080000, THREAD, 2448 ("method-signature_index change: %d to %d", 2449 method->signature_index(), new_index)); 2450 method->set_signature_index(new_index); 2451 } 2452 new_index = find_new_index(method->generic_signature_index()); 2453 if (new_index != 0) { 2454 RC_TRACE_WITH_THREAD(0x00080000, THREAD, 2455 ("method-generic_signature_index change: %d to %d", 2456 method->generic_signature_index(), new_index)); 2457 method->set_generic_signature_index(new_index); 2458 } 2459 2460 // Update constant pool indices in the method's checked exception 2461 // table to use new constant indices as needed. 2462 int cext_length = method->checked_exceptions_length(); 2463 if (cext_length > 0) { 2464 CheckedExceptionElement * cext_table = 2465 method->checked_exceptions_start(); 2466 for (int j = 0; j < cext_length; j++) { 2467 int cur_index = cext_table[j].class_cp_index; 2468 int new_index = find_new_index(cur_index); 2469 if (new_index != 0) { 2470 RC_TRACE_WITH_THREAD(0x00080000, THREAD, 2471 ("cext-class_cp_index change: %d to %d", cur_index, new_index)); 2472 cext_table[j].class_cp_index = (u2)new_index; 2473 } 2474 } // end for each checked exception table entry 2475 } // end if there are checked exception table entries 2476 2477 // Update each catch type index in the method's exception table 2478 // to use new constant pool indices as needed. The exception table 2479 // holds quadruple entries of the form: 2480 // (beg_bci, end_bci, handler_bci, klass_index) 2481 const int beg_bci_offset = 0; 2482 const int end_bci_offset = 1; 2483 const int handler_bci_offset = 2; 2484 const int klass_index_offset = 3; 2485 const int entry_size = 4; 2486 2487 typeArrayHandle ex_table (THREAD, method->exception_table()); 2488 int ext_length = ex_table->length(); 2489 assert(ext_length % entry_size == 0, "exception table format has changed"); 2490 2491 for (int j = 0; j < ext_length; j += entry_size) { 2492 int cur_index = ex_table->int_at(j + klass_index_offset); 2493 int new_index = find_new_index(cur_index); 2494 if (new_index != 0) { 2495 RC_TRACE_WITH_THREAD(0x00080000, THREAD, 2496 ("ext-klass_index change: %d to %d", cur_index, new_index)); 2497 ex_table->int_at_put(j + klass_index_offset, new_index); 2498 } 2499 } // end for each exception table entry 2500 2501 // Update constant pool indices in the method's local variable 2502 // table to use new constant indices as needed. The local variable 2503 // table hold sextuple entries of the form: 2504 // (start_pc, length, name_index, descriptor_index, signature_index, slot) 2505 int lvt_length = method->localvariable_table_length(); 2506 if (lvt_length > 0) { 2507 LocalVariableTableElement * lv_table = 2508 method->localvariable_table_start(); 2509 for (int j = 0; j < lvt_length; j++) { 2510 int cur_index = lv_table[j].name_cp_index; 2511 int new_index = find_new_index(cur_index); 2512 if (new_index != 0) { 2513 RC_TRACE_WITH_THREAD(0x00080000, THREAD, 2514 ("lvt-name_cp_index change: %d to %d", cur_index, new_index)); 2515 lv_table[j].name_cp_index = (u2)new_index; 2516 } 2517 cur_index = lv_table[j].descriptor_cp_index; 2518 new_index = find_new_index(cur_index); 2519 if (new_index != 0) { 2520 RC_TRACE_WITH_THREAD(0x00080000, THREAD, 2521 ("lvt-descriptor_cp_index change: %d to %d", cur_index, 2522 new_index)); 2523 lv_table[j].descriptor_cp_index = (u2)new_index; 2524 } 2525 cur_index = lv_table[j].signature_cp_index; 2526 new_index = find_new_index(cur_index); 2527 if (new_index != 0) { 2528 RC_TRACE_WITH_THREAD(0x00080000, THREAD, 2529 ("lvt-signature_cp_index change: %d to %d", cur_index, new_index)); 2530 lv_table[j].signature_cp_index = (u2)new_index; 2531 } 2532 } // end for each local variable table entry 2533 } // end if there are local variable table entries 2534 2535 rewrite_cp_refs_in_stack_map_table(method, THREAD); 2536 } // end for each method 2537 assert(scratch_cp()->is_conc_safe(), "Just checking"); 2538 } // end set_new_constant_pool() 2539 2540 2541 // Unevolving classes may point to methods of the_class directly 2542 // from their constant pool caches, itables, and/or vtables. We 2543 // use the SystemDictionary::classes_do() facility and this helper 2544 // to fix up these pointers. 2545 // 2546 // Note: We currently don't support updating the vtable in 2547 // arrayKlassOops. See Open Issues in jvmtiRedefineClasses.hpp. 2548 void VM_RedefineClasses::adjust_cpool_cache_and_vtable(klassOop k_oop, 2549 oop initiating_loader, TRAPS) { 2550 Klass *k = k_oop->klass_part(); 2551 if (k->oop_is_instance()) { 2552 HandleMark hm(THREAD); 2553 instanceKlass *ik = (instanceKlass *) k; 2554 2555 // HotSpot specific optimization! HotSpot does not currently 2556 // support delegation from the bootstrap class loader to a 2557 // user-defined class loader. This means that if the bootstrap 2558 // class loader is the initiating class loader, then it will also 2559 // be the defining class loader. This also means that classes 2560 // loaded by the bootstrap class loader cannot refer to classes 2561 // loaded by a user-defined class loader. Note: a user-defined 2562 // class loader can delegate to the bootstrap class loader. 2563 // 2564 // If the current class being redefined has a user-defined class 2565 // loader as its defining class loader, then we can skip all 2566 // classes loaded by the bootstrap class loader. 2567 bool is_user_defined = 2568 instanceKlass::cast(_the_class_oop)->class_loader() != NULL; 2569 if (is_user_defined && ik->class_loader() == NULL) { 2570 return; 2571 } 2572 2573 // This is a very busy routine. We don't want too much tracing 2574 // printed out. 2575 bool trace_name_printed = false; 2576 2577 // Very noisy: only enable this call if you are trying to determine 2578 // that a specific class gets found by this routine. 2579 // RC_TRACE macro has an embedded ResourceMark 2580 // RC_TRACE_WITH_THREAD(0x00100000, THREAD, 2581 // ("adjust check: name=%s", ik->external_name())); 2582 // trace_name_printed = true; 2583 2584 // Fix the vtable embedded in the_class and subclasses of the_class, 2585 // if one exists. We discard scratch_class and we don't keep an 2586 // instanceKlass around to hold obsolete methods so we don't have 2587 // any other instanceKlass embedded vtables to update. The vtable 2588 // holds the methodOops for virtual (but not final) methods. 2589 if (ik->vtable_length() > 0 && ik->is_subtype_of(_the_class_oop)) { 2590 // ik->vtable() creates a wrapper object; rm cleans it up 2591 ResourceMark rm(THREAD); 2592 ik->vtable()->adjust_method_entries(_matching_old_methods, 2593 _matching_new_methods, 2594 _matching_methods_length, 2595 &trace_name_printed); 2596 } 2597 2598 // If the current class has an itable and we are either redefining an 2599 // interface or if the current class is a subclass of the_class, then 2600 // we potentially have to fix the itable. If we are redefining an 2601 // interface, then we have to call adjust_method_entries() for 2602 // every instanceKlass that has an itable since there isn't a 2603 // subclass relationship between an interface and an instanceKlass. 2604 if (ik->itable_length() > 0 && (Klass::cast(_the_class_oop)->is_interface() 2605 || ik->is_subclass_of(_the_class_oop))) { 2606 // ik->itable() creates a wrapper object; rm cleans it up 2607 ResourceMark rm(THREAD); 2608 ik->itable()->adjust_method_entries(_matching_old_methods, 2609 _matching_new_methods, 2610 _matching_methods_length, 2611 &trace_name_printed); 2612 } 2613 2614 // The constant pools in other classes (other_cp) can refer to 2615 // methods in the_class. We have to update method information in 2616 // other_cp's cache. If other_cp has a previous version, then we 2617 // have to repeat the process for each previous version. The 2618 // constant pool cache holds the methodOops for non-virtual 2619 // methods and for virtual, final methods. 2620 // 2621 // Special case: if the current class is the_class, then new_cp 2622 // has already been attached to the_class and old_cp has already 2623 // been added as a previous version. The new_cp doesn't have any 2624 // cached references to old methods so it doesn't need to be 2625 // updated. We can simply start with the previous version(s) in 2626 // that case. 2627 constantPoolHandle other_cp; 2628 constantPoolCacheOop cp_cache; 2629 2630 if (k_oop != _the_class_oop) { 2631 // this klass' constant pool cache may need adjustment 2632 other_cp = constantPoolHandle(ik->constants()); 2633 cp_cache = other_cp->cache(); 2634 if (cp_cache != NULL) { 2635 cp_cache->adjust_method_entries(_matching_old_methods, 2636 _matching_new_methods, 2637 _matching_methods_length, 2638 &trace_name_printed); 2639 } 2640 } 2641 { 2642 ResourceMark rm(THREAD); 2643 // PreviousVersionInfo objects returned via PreviousVersionWalker 2644 // contain a GrowableArray of handles. We have to clean up the 2645 // GrowableArray _after_ the PreviousVersionWalker destructor 2646 // has destroyed the handles. 2647 { 2648 // the previous versions' constant pool caches may need adjustment 2649 PreviousVersionWalker pvw(ik); 2650 for (PreviousVersionInfo * pv_info = pvw.next_previous_version(); 2651 pv_info != NULL; pv_info = pvw.next_previous_version()) { 2652 other_cp = pv_info->prev_constant_pool_handle(); 2653 cp_cache = other_cp->cache(); 2654 if (cp_cache != NULL) { 2655 cp_cache->adjust_method_entries(_matching_old_methods, 2656 _matching_new_methods, 2657 _matching_methods_length, 2658 &trace_name_printed); 2659 } 2660 } 2661 } // pvw is cleaned up 2662 } // rm is cleaned up 2663 } 2664 } 2665 2666 void VM_RedefineClasses::update_jmethod_ids() { 2667 for (int j = 0; j < _matching_methods_length; ++j) { 2668 methodOop old_method = _matching_old_methods[j]; 2669 jmethodID jmid = old_method->find_jmethod_id_or_null(); 2670 if (jmid != NULL) { 2671 // There is a jmethodID, change it to point to the new method 2672 methodHandle new_method_h(_matching_new_methods[j]); 2673 JNIHandles::change_method_associated_with_jmethod_id(jmid, new_method_h); 2674 assert(JNIHandles::resolve_jmethod_id(jmid) == _matching_new_methods[j], 2675 "should be replaced"); 2676 } 2677 } 2678 } 2679 2680 void VM_RedefineClasses::check_methods_and_mark_as_obsolete( 2681 BitMap *emcp_methods, int * emcp_method_count_p) { 2682 *emcp_method_count_p = 0; 2683 int obsolete_count = 0; 2684 int old_index = 0; 2685 for (int j = 0; j < _matching_methods_length; ++j, ++old_index) { 2686 methodOop old_method = _matching_old_methods[j]; 2687 methodOop new_method = _matching_new_methods[j]; 2688 methodOop old_array_method; 2689 2690 // Maintain an old_index into the _old_methods array by skipping 2691 // deleted methods 2692 while ((old_array_method = (methodOop) _old_methods->obj_at(old_index)) 2693 != old_method) { 2694 ++old_index; 2695 } 2696 2697 if (MethodComparator::methods_EMCP(old_method, new_method)) { 2698 // The EMCP definition from JSR-163 requires the bytecodes to be 2699 // the same with the exception of constant pool indices which may 2700 // differ. However, the constants referred to by those indices 2701 // must be the same. 2702 // 2703 // We use methods_EMCP() for comparison since constant pool 2704 // merging can remove duplicate constant pool entries that were 2705 // present in the old method and removed from the rewritten new 2706 // method. A faster binary comparison function would consider the 2707 // old and new methods to be different when they are actually 2708 // EMCP. 2709 // 2710 // The old and new methods are EMCP and you would think that we 2711 // could get rid of one of them here and now and save some space. 2712 // However, the concept of EMCP only considers the bytecodes and 2713 // the constant pool entries in the comparison. Other things, 2714 // e.g., the line number table (LNT) or the local variable table 2715 // (LVT) don't count in the comparison. So the new (and EMCP) 2716 // method can have a new LNT that we need so we can't just 2717 // overwrite the new method with the old method. 2718 // 2719 // When this routine is called, we have already attached the new 2720 // methods to the_class so the old methods are effectively 2721 // overwritten. However, if an old method is still executing, 2722 // then the old method cannot be collected until sometime after 2723 // the old method call has returned. So the overwriting of old 2724 // methods by new methods will save us space except for those 2725 // (hopefully few) old methods that are still executing. 2726 // 2727 // A method refers to a constMethodOop and this presents another 2728 // possible avenue to space savings. The constMethodOop in the 2729 // new method contains possibly new attributes (LNT, LVT, etc). 2730 // At first glance, it seems possible to save space by replacing 2731 // the constMethodOop in the old method with the constMethodOop 2732 // from the new method. The old and new methods would share the 2733 // same constMethodOop and we would save the space occupied by 2734 // the old constMethodOop. However, the constMethodOop contains 2735 // a back reference to the containing method. Sharing the 2736 // constMethodOop between two methods could lead to confusion in 2737 // the code that uses the back reference. This would lead to 2738 // brittle code that could be broken in non-obvious ways now or 2739 // in the future. 2740 // 2741 // Another possibility is to copy the constMethodOop from the new 2742 // method to the old method and then overwrite the new method with 2743 // the old method. Since the constMethodOop contains the bytecodes 2744 // for the method embedded in the oop, this option would change 2745 // the bytecodes out from under any threads executing the old 2746 // method and make the thread's bcp invalid. Since EMCP requires 2747 // that the bytecodes be the same modulo constant pool indices, it 2748 // is straight forward to compute the correct new bcp in the new 2749 // constMethodOop from the old bcp in the old constMethodOop. The 2750 // time consuming part would be searching all the frames in all 2751 // of the threads to find all of the calls to the old method. 2752 // 2753 // It looks like we will have to live with the limited savings 2754 // that we get from effectively overwriting the old methods 2755 // when the new methods are attached to the_class. 2756 2757 // track which methods are EMCP for add_previous_version() call 2758 emcp_methods->set_bit(old_index); 2759 (*emcp_method_count_p)++; 2760 2761 // An EMCP method is _not_ obsolete. An obsolete method has a 2762 // different jmethodID than the current method. An EMCP method 2763 // has the same jmethodID as the current method. Having the 2764 // same jmethodID for all EMCP versions of a method allows for 2765 // a consistent view of the EMCP methods regardless of which 2766 // EMCP method you happen to have in hand. For example, a 2767 // breakpoint set in one EMCP method will work for all EMCP 2768 // versions of the method including the current one. 2769 } else { 2770 // mark obsolete methods as such 2771 old_method->set_is_obsolete(); 2772 obsolete_count++; 2773 2774 // obsolete methods need a unique idnum 2775 u2 num = instanceKlass::cast(_the_class_oop)->next_method_idnum(); 2776 if (num != constMethodOopDesc::UNSET_IDNUM) { 2777 // u2 old_num = old_method->method_idnum(); 2778 old_method->set_method_idnum(num); 2779 // TO DO: attach obsolete annotations to obsolete method's new idnum 2780 } 2781 // With tracing we try not to "yack" too much. The position of 2782 // this trace assumes there are fewer obsolete methods than 2783 // EMCP methods. 2784 RC_TRACE(0x00000100, ("mark %s(%s) as obsolete", 2785 old_method->name()->as_C_string(), 2786 old_method->signature()->as_C_string())); 2787 } 2788 old_method->set_is_old(); 2789 } 2790 for (int i = 0; i < _deleted_methods_length; ++i) { 2791 methodOop old_method = _deleted_methods[i]; 2792 2793 assert(old_method->vtable_index() < 0, 2794 "cannot delete methods with vtable entries");; 2795 2796 // Mark all deleted methods as old and obsolete 2797 old_method->set_is_old(); 2798 old_method->set_is_obsolete(); 2799 ++obsolete_count; 2800 // With tracing we try not to "yack" too much. The position of 2801 // this trace assumes there are fewer obsolete methods than 2802 // EMCP methods. 2803 RC_TRACE(0x00000100, ("mark deleted %s(%s) as obsolete", 2804 old_method->name()->as_C_string(), 2805 old_method->signature()->as_C_string())); 2806 } 2807 assert((*emcp_method_count_p + obsolete_count) == _old_methods->length(), 2808 "sanity check"); 2809 RC_TRACE(0x00000100, ("EMCP_cnt=%d, obsolete_cnt=%d", *emcp_method_count_p, 2810 obsolete_count)); 2811 } 2812 2813 // This internal class transfers the native function registration from old methods 2814 // to new methods. It is designed to handle both the simple case of unchanged 2815 // native methods and the complex cases of native method prefixes being added and/or 2816 // removed. 2817 // It expects only to be used during the VM_RedefineClasses op (a safepoint). 2818 // 2819 // This class is used after the new methods have been installed in "the_class". 2820 // 2821 // So, for example, the following must be handled. Where 'm' is a method and 2822 // a number followed by an underscore is a prefix. 2823 // 2824 // Old Name New Name 2825 // Simple transfer to new method m -> m 2826 // Add prefix m -> 1_m 2827 // Remove prefix 1_m -> m 2828 // Simultaneous add of prefixes m -> 3_2_1_m 2829 // Simultaneous removal of prefixes 3_2_1_m -> m 2830 // Simultaneous add and remove 1_m -> 2_m 2831 // Same, caused by prefix removal only 3_2_1_m -> 3_2_m 2832 // 2833 class TransferNativeFunctionRegistration { 2834 private: 2835 instanceKlassHandle the_class; 2836 int prefix_count; 2837 char** prefixes; 2838 2839 // Recursively search the binary tree of possibly prefixed method names. 2840 // Iteration could be used if all agents were well behaved. Full tree walk is 2841 // more resilent to agents not cleaning up intermediate methods. 2842 // Branch at each depth in the binary tree is: 2843 // (1) without the prefix. 2844 // (2) with the prefix. 2845 // where 'prefix' is the prefix at that 'depth' (first prefix, second prefix,...) 2846 methodOop search_prefix_name_space(int depth, char* name_str, size_t name_len, 2847 Symbol* signature) { 2848 TempNewSymbol name_symbol = SymbolTable::probe(name_str, (int)name_len); 2849 if (name_symbol != NULL) { 2850 methodOop method = Klass::cast(the_class())->lookup_method(name_symbol, signature); 2851 if (method != NULL) { 2852 // Even if prefixed, intermediate methods must exist. 2853 if (method->is_native()) { 2854 // Wahoo, we found a (possibly prefixed) version of the method, return it. 2855 return method; 2856 } 2857 if (depth < prefix_count) { 2858 // Try applying further prefixes (other than this one). 2859 method = search_prefix_name_space(depth+1, name_str, name_len, signature); 2860 if (method != NULL) { 2861 return method; // found 2862 } 2863 2864 // Try adding this prefix to the method name and see if it matches 2865 // another method name. 2866 char* prefix = prefixes[depth]; 2867 size_t prefix_len = strlen(prefix); 2868 size_t trial_len = name_len + prefix_len; 2869 char* trial_name_str = NEW_RESOURCE_ARRAY(char, trial_len + 1); 2870 strcpy(trial_name_str, prefix); 2871 strcat(trial_name_str, name_str); 2872 method = search_prefix_name_space(depth+1, trial_name_str, trial_len, 2873 signature); 2874 if (method != NULL) { 2875 // If found along this branch, it was prefixed, mark as such 2876 method->set_is_prefixed_native(); 2877 return method; // found 2878 } 2879 } 2880 } 2881 } 2882 return NULL; // This whole branch bore nothing 2883 } 2884 2885 // Return the method name with old prefixes stripped away. 2886 char* method_name_without_prefixes(methodOop method) { 2887 Symbol* name = method->name(); 2888 char* name_str = name->as_utf8(); 2889 2890 // Old prefixing may be defunct, strip prefixes, if any. 2891 for (int i = prefix_count-1; i >= 0; i--) { 2892 char* prefix = prefixes[i]; 2893 size_t prefix_len = strlen(prefix); 2894 if (strncmp(prefix, name_str, prefix_len) == 0) { 2895 name_str += prefix_len; 2896 } 2897 } 2898 return name_str; 2899 } 2900 2901 // Strip any prefixes off the old native method, then try to find a 2902 // (possibly prefixed) new native that matches it. 2903 methodOop strip_and_search_for_new_native(methodOop method) { 2904 ResourceMark rm; 2905 char* name_str = method_name_without_prefixes(method); 2906 return search_prefix_name_space(0, name_str, strlen(name_str), 2907 method->signature()); 2908 } 2909 2910 public: 2911 2912 // Construct a native method transfer processor for this class. 2913 TransferNativeFunctionRegistration(instanceKlassHandle _the_class) { 2914 assert(SafepointSynchronize::is_at_safepoint(), "sanity check"); 2915 2916 the_class = _the_class; 2917 prefixes = JvmtiExport::get_all_native_method_prefixes(&prefix_count); 2918 } 2919 2920 // Attempt to transfer any of the old or deleted methods that are native 2921 void transfer_registrations(methodOop* old_methods, int methods_length) { 2922 for (int j = 0; j < methods_length; j++) { 2923 methodOop old_method = old_methods[j]; 2924 2925 if (old_method->is_native() && old_method->has_native_function()) { 2926 methodOop new_method = strip_and_search_for_new_native(old_method); 2927 if (new_method != NULL) { 2928 // Actually set the native function in the new method. 2929 // Redefine does not send events (except CFLH), certainly not this 2930 // behind the scenes re-registration. 2931 new_method->set_native_function(old_method->native_function(), 2932 !methodOopDesc::native_bind_event_is_interesting); 2933 } 2934 } 2935 } 2936 } 2937 }; 2938 2939 // Don't lose the association between a native method and its JNI function. 2940 void VM_RedefineClasses::transfer_old_native_function_registrations(instanceKlassHandle the_class) { 2941 TransferNativeFunctionRegistration transfer(the_class); 2942 transfer.transfer_registrations(_deleted_methods, _deleted_methods_length); 2943 transfer.transfer_registrations(_matching_old_methods, _matching_methods_length); 2944 } 2945 2946 // Deoptimize all compiled code that depends on this class. 2947 // 2948 // If the can_redefine_classes capability is obtained in the onload 2949 // phase then the compiler has recorded all dependencies from startup. 2950 // In that case we need only deoptimize and throw away all compiled code 2951 // that depends on the class. 2952 // 2953 // If can_redefine_classes is obtained sometime after the onload 2954 // phase then the dependency information may be incomplete. In that case 2955 // the first call to RedefineClasses causes all compiled code to be 2956 // thrown away. As can_redefine_classes has been obtained then 2957 // all future compilations will record dependencies so second and 2958 // subsequent calls to RedefineClasses need only throw away code 2959 // that depends on the class. 2960 // 2961 void VM_RedefineClasses::flush_dependent_code(instanceKlassHandle k_h, TRAPS) { 2962 assert_locked_or_safepoint(Compile_lock); 2963 2964 // All dependencies have been recorded from startup or this is a second or 2965 // subsequent use of RedefineClasses 2966 if (JvmtiExport::all_dependencies_are_recorded()) { 2967 Universe::flush_evol_dependents_on(k_h); 2968 } else { 2969 CodeCache::mark_all_nmethods_for_deoptimization(); 2970 2971 ResourceMark rm(THREAD); 2972 DeoptimizationMarker dm; 2973 2974 // Deoptimize all activations depending on marked nmethods 2975 Deoptimization::deoptimize_dependents(); 2976 2977 // Make the dependent methods not entrant (in VM_Deoptimize they are made zombies) 2978 CodeCache::make_marked_nmethods_not_entrant(); 2979 2980 // From now on we know that the dependency information is complete 2981 JvmtiExport::set_all_dependencies_are_recorded(true); 2982 } 2983 } 2984 2985 void VM_RedefineClasses::compute_added_deleted_matching_methods() { 2986 methodOop old_method; 2987 methodOop new_method; 2988 2989 _matching_old_methods = NEW_RESOURCE_ARRAY(methodOop, _old_methods->length()); 2990 _matching_new_methods = NEW_RESOURCE_ARRAY(methodOop, _old_methods->length()); 2991 _added_methods = NEW_RESOURCE_ARRAY(methodOop, _new_methods->length()); 2992 _deleted_methods = NEW_RESOURCE_ARRAY(methodOop, _old_methods->length()); 2993 2994 _matching_methods_length = 0; 2995 _deleted_methods_length = 0; 2996 _added_methods_length = 0; 2997 2998 int nj = 0; 2999 int oj = 0; 3000 while (true) { 3001 if (oj >= _old_methods->length()) { 3002 if (nj >= _new_methods->length()) { 3003 break; // we've looked at everything, done 3004 } 3005 // New method at the end 3006 new_method = (methodOop) _new_methods->obj_at(nj); 3007 _added_methods[_added_methods_length++] = new_method; 3008 ++nj; 3009 } else if (nj >= _new_methods->length()) { 3010 // Old method, at the end, is deleted 3011 old_method = (methodOop) _old_methods->obj_at(oj); 3012 _deleted_methods[_deleted_methods_length++] = old_method; 3013 ++oj; 3014 } else { 3015 old_method = (methodOop) _old_methods->obj_at(oj); 3016 new_method = (methodOop) _new_methods->obj_at(nj); 3017 if (old_method->name() == new_method->name()) { 3018 if (old_method->signature() == new_method->signature()) { 3019 _matching_old_methods[_matching_methods_length ] = old_method; 3020 _matching_new_methods[_matching_methods_length++] = new_method; 3021 ++nj; 3022 ++oj; 3023 } else { 3024 // added overloaded have already been moved to the end, 3025 // so this is a deleted overloaded method 3026 _deleted_methods[_deleted_methods_length++] = old_method; 3027 ++oj; 3028 } 3029 } else { // names don't match 3030 if (old_method->name()->fast_compare(new_method->name()) > 0) { 3031 // new method 3032 _added_methods[_added_methods_length++] = new_method; 3033 ++nj; 3034 } else { 3035 // deleted method 3036 _deleted_methods[_deleted_methods_length++] = old_method; 3037 ++oj; 3038 } 3039 } 3040 } 3041 } 3042 assert(_matching_methods_length + _deleted_methods_length == _old_methods->length(), "sanity"); 3043 assert(_matching_methods_length + _added_methods_length == _new_methods->length(), "sanity"); 3044 } 3045 3046 3047 3048 // Install the redefinition of a class: 3049 // - house keeping (flushing breakpoints and caches, deoptimizing 3050 // dependent compiled code) 3051 // - replacing parts in the_class with parts from scratch_class 3052 // - adding a weak reference to track the obsolete but interesting 3053 // parts of the_class 3054 // - adjusting constant pool caches and vtables in other classes 3055 // that refer to methods in the_class. These adjustments use the 3056 // SystemDictionary::classes_do() facility which only allows 3057 // a helper method to be specified. The interesting parameters 3058 // that we would like to pass to the helper method are saved in 3059 // static global fields in the VM operation. 3060 void VM_RedefineClasses::redefine_single_class(jclass the_jclass, 3061 instanceKlassHandle scratch_class, TRAPS) { 3062 3063 RC_TIMER_START(_timer_rsc_phase1); 3064 3065 oop the_class_mirror = JNIHandles::resolve_non_null(the_jclass); 3066 klassOop the_class_oop = java_lang_Class::as_klassOop(the_class_mirror); 3067 instanceKlassHandle the_class = instanceKlassHandle(THREAD, the_class_oop); 3068 3069 #ifndef JVMTI_KERNEL 3070 // Remove all breakpoints in methods of this class 3071 JvmtiBreakpoints& jvmti_breakpoints = JvmtiCurrentBreakpoints::get_jvmti_breakpoints(); 3072 jvmti_breakpoints.clearall_in_class_at_safepoint(the_class_oop); 3073 #endif // !JVMTI_KERNEL 3074 3075 if (the_class_oop == Universe::reflect_invoke_cache()->klass()) { 3076 // We are redefining java.lang.reflect.Method. Method.invoke() is 3077 // cached and users of the cache care about each active version of 3078 // the method so we have to track this previous version. 3079 // Do this before methods get switched 3080 Universe::reflect_invoke_cache()->add_previous_version( 3081 the_class->method_with_idnum(Universe::reflect_invoke_cache()->method_idnum())); 3082 } 3083 3084 // Deoptimize all compiled code that depends on this class 3085 flush_dependent_code(the_class, THREAD); 3086 3087 _old_methods = the_class->methods(); 3088 _new_methods = scratch_class->methods(); 3089 _the_class_oop = the_class_oop; 3090 compute_added_deleted_matching_methods(); 3091 update_jmethod_ids(); 3092 3093 // Attach new constant pool to the original klass. The original 3094 // klass still refers to the old constant pool (for now). 3095 scratch_class->constants()->set_pool_holder(the_class()); 3096 3097 #if 0 3098 // In theory, with constant pool merging in place we should be able 3099 // to save space by using the new, merged constant pool in place of 3100 // the old constant pool(s). By "pool(s)" I mean the constant pool in 3101 // the klass version we are replacing now and any constant pool(s) in 3102 // previous versions of klass. Nice theory, doesn't work in practice. 3103 // When this code is enabled, even simple programs throw NullPointer 3104 // exceptions. I'm guessing that this is caused by some constant pool 3105 // cache difference between the new, merged constant pool and the 3106 // constant pool that was just being used by the klass. I'm keeping 3107 // this code around to archive the idea, but the code has to remain 3108 // disabled for now. 3109 3110 // Attach each old method to the new constant pool. This can be 3111 // done here since we are past the bytecode verification and 3112 // constant pool optimization phases. 3113 for (int i = _old_methods->length() - 1; i >= 0; i--) { 3114 methodOop method = (methodOop)_old_methods->obj_at(i); 3115 method->set_constants(scratch_class->constants()); 3116 } 3117 3118 { 3119 // walk all previous versions of the klass 3120 instanceKlass *ik = (instanceKlass *)the_class()->klass_part(); 3121 PreviousVersionWalker pvw(ik); 3122 instanceKlassHandle ikh; 3123 do { 3124 ikh = pvw.next_previous_version(); 3125 if (!ikh.is_null()) { 3126 ik = ikh(); 3127 3128 // attach previous version of klass to the new constant pool 3129 ik->set_constants(scratch_class->constants()); 3130 3131 // Attach each method in the previous version of klass to the 3132 // new constant pool 3133 objArrayOop prev_methods = ik->methods(); 3134 for (int i = prev_methods->length() - 1; i >= 0; i--) { 3135 methodOop method = (methodOop)prev_methods->obj_at(i); 3136 method->set_constants(scratch_class->constants()); 3137 } 3138 } 3139 } while (!ikh.is_null()); 3140 } 3141 #endif 3142 3143 // Replace methods and constantpool 3144 the_class->set_methods(_new_methods); 3145 scratch_class->set_methods(_old_methods); // To prevent potential GCing of the old methods, 3146 // and to be able to undo operation easily. 3147 3148 constantPoolOop old_constants = the_class->constants(); 3149 the_class->set_constants(scratch_class->constants()); 3150 scratch_class->set_constants(old_constants); // See the previous comment. 3151 #if 0 3152 // We are swapping the guts of "the new class" with the guts of "the 3153 // class". Since the old constant pool has just been attached to "the 3154 // new class", it seems logical to set the pool holder in the old 3155 // constant pool also. However, doing this will change the observable 3156 // class hierarchy for any old methods that are still executing. A 3157 // method can query the identity of its "holder" and this query uses 3158 // the method's constant pool link to find the holder. The change in 3159 // holding class from "the class" to "the new class" can confuse 3160 // things. 3161 // 3162 // Setting the old constant pool's holder will also cause 3163 // verification done during vtable initialization below to fail. 3164 // During vtable initialization, the vtable's class is verified to be 3165 // a subtype of the method's holder. The vtable's class is "the 3166 // class" and the method's holder is gotten from the constant pool 3167 // link in the method itself. For "the class"'s directly implemented 3168 // methods, the method holder is "the class" itself (as gotten from 3169 // the new constant pool). The check works fine in this case. The 3170 // check also works fine for methods inherited from super classes. 3171 // 3172 // Miranda methods are a little more complicated. A miranda method is 3173 // provided by an interface when the class implementing the interface 3174 // does not provide its own method. These interfaces are implemented 3175 // internally as an instanceKlass. These special instanceKlasses 3176 // share the constant pool of the class that "implements" the 3177 // interface. By sharing the constant pool, the method holder of a 3178 // miranda method is the class that "implements" the interface. In a 3179 // non-redefine situation, the subtype check works fine. However, if 3180 // the old constant pool's pool holder is modified, then the check 3181 // fails because there is no class hierarchy relationship between the 3182 // vtable's class and "the new class". 3183 3184 old_constants->set_pool_holder(scratch_class()); 3185 #endif 3186 3187 // track which methods are EMCP for add_previous_version() call below 3188 BitMap emcp_methods(_old_methods->length()); 3189 int emcp_method_count = 0; 3190 emcp_methods.clear(); // clears 0..(length() - 1) 3191 check_methods_and_mark_as_obsolete(&emcp_methods, &emcp_method_count); 3192 transfer_old_native_function_registrations(the_class); 3193 3194 // The class file bytes from before any retransformable agents mucked 3195 // with them was cached on the scratch class, move to the_class. 3196 // Note: we still want to do this if nothing needed caching since it 3197 // should get cleared in the_class too. 3198 if (the_class->get_cached_class_file_bytes() == 0) { 3199 // the_class doesn't have a cache yet so copy it 3200 the_class->set_cached_class_file( 3201 scratch_class->get_cached_class_file_bytes(), 3202 scratch_class->get_cached_class_file_len()); 3203 } 3204 #ifndef PRODUCT 3205 else { 3206 assert(the_class->get_cached_class_file_bytes() == 3207 scratch_class->get_cached_class_file_bytes(), "cache ptrs must match"); 3208 assert(the_class->get_cached_class_file_len() == 3209 scratch_class->get_cached_class_file_len(), "cache lens must match"); 3210 } 3211 #endif 3212 3213 // Replace inner_classes 3214 typeArrayOop old_inner_classes = the_class->inner_classes(); 3215 the_class->set_inner_classes(scratch_class->inner_classes()); 3216 scratch_class->set_inner_classes(old_inner_classes); 3217 3218 // Initialize the vtable and interface table after 3219 // methods have been rewritten 3220 { 3221 ResourceMark rm(THREAD); 3222 // no exception should happen here since we explicitly 3223 // do not check loader constraints. 3224 // compare_and_normalize_class_versions has already checked: 3225 // - classloaders unchanged, signatures unchanged 3226 // - all instanceKlasses for redefined classes reused & contents updated 3227 the_class->vtable()->initialize_vtable(false, THREAD); 3228 the_class->itable()->initialize_itable(false, THREAD); 3229 assert(!HAS_PENDING_EXCEPTION || (THREAD->pending_exception()->is_a(SystemDictionary::ThreadDeath_klass())), "redefine exception"); 3230 } 3231 3232 // Leave arrays of jmethodIDs and itable index cache unchanged 3233 3234 // Copy the "source file name" attribute from new class version 3235 the_class->set_source_file_name(scratch_class->source_file_name()); 3236 3237 // Copy the "source debug extension" attribute from new class version 3238 the_class->set_source_debug_extension( 3239 scratch_class->source_debug_extension()); 3240 3241 // Use of javac -g could be different in the old and the new 3242 if (scratch_class->access_flags().has_localvariable_table() != 3243 the_class->access_flags().has_localvariable_table()) { 3244 3245 AccessFlags flags = the_class->access_flags(); 3246 if (scratch_class->access_flags().has_localvariable_table()) { 3247 flags.set_has_localvariable_table(); 3248 } else { 3249 flags.clear_has_localvariable_table(); 3250 } 3251 the_class->set_access_flags(flags); 3252 } 3253 3254 // Replace class annotation fields values 3255 typeArrayOop old_class_annotations = the_class->class_annotations(); 3256 the_class->set_class_annotations(scratch_class->class_annotations()); 3257 scratch_class->set_class_annotations(old_class_annotations); 3258 3259 // Replace fields annotation fields values 3260 objArrayOop old_fields_annotations = the_class->fields_annotations(); 3261 the_class->set_fields_annotations(scratch_class->fields_annotations()); 3262 scratch_class->set_fields_annotations(old_fields_annotations); 3263 3264 // Replace methods annotation fields values 3265 objArrayOop old_methods_annotations = the_class->methods_annotations(); 3266 the_class->set_methods_annotations(scratch_class->methods_annotations()); 3267 scratch_class->set_methods_annotations(old_methods_annotations); 3268 3269 // Replace methods parameter annotation fields values 3270 objArrayOop old_methods_parameter_annotations = 3271 the_class->methods_parameter_annotations(); 3272 the_class->set_methods_parameter_annotations( 3273 scratch_class->methods_parameter_annotations()); 3274 scratch_class->set_methods_parameter_annotations(old_methods_parameter_annotations); 3275 3276 // Replace methods default annotation fields values 3277 objArrayOop old_methods_default_annotations = 3278 the_class->methods_default_annotations(); 3279 the_class->set_methods_default_annotations( 3280 scratch_class->methods_default_annotations()); 3281 scratch_class->set_methods_default_annotations(old_methods_default_annotations); 3282 3283 // Replace minor version number of class file 3284 u2 old_minor_version = the_class->minor_version(); 3285 the_class->set_minor_version(scratch_class->minor_version()); 3286 scratch_class->set_minor_version(old_minor_version); 3287 3288 // Replace major version number of class file 3289 u2 old_major_version = the_class->major_version(); 3290 the_class->set_major_version(scratch_class->major_version()); 3291 scratch_class->set_major_version(old_major_version); 3292 3293 // Replace CP indexes for class and name+type of enclosing method 3294 u2 old_class_idx = the_class->enclosing_method_class_index(); 3295 u2 old_method_idx = the_class->enclosing_method_method_index(); 3296 the_class->set_enclosing_method_indices( 3297 scratch_class->enclosing_method_class_index(), 3298 scratch_class->enclosing_method_method_index()); 3299 scratch_class->set_enclosing_method_indices(old_class_idx, old_method_idx); 3300 3301 // keep track of previous versions of this class 3302 the_class->add_previous_version(scratch_class, &emcp_methods, 3303 emcp_method_count); 3304 3305 RC_TIMER_STOP(_timer_rsc_phase1); 3306 RC_TIMER_START(_timer_rsc_phase2); 3307 3308 // Adjust constantpool caches and vtables for all classes 3309 // that reference methods of the evolved class. 3310 SystemDictionary::classes_do(adjust_cpool_cache_and_vtable, THREAD); 3311 3312 if (the_class->oop_map_cache() != NULL) { 3313 // Flush references to any obsolete methods from the oop map cache 3314 // so that obsolete methods are not pinned. 3315 the_class->oop_map_cache()->flush_obsolete_entries(); 3316 } 3317 3318 // increment the classRedefinedCount field in the_class and in any 3319 // direct and indirect subclasses of the_class 3320 increment_class_counter((instanceKlass *)the_class()->klass_part(), THREAD); 3321 3322 // RC_TRACE macro has an embedded ResourceMark 3323 RC_TRACE_WITH_THREAD(0x00000001, THREAD, 3324 ("redefined name=%s, count=%d (avail_mem=" UINT64_FORMAT "K)", 3325 the_class->external_name(), 3326 java_lang_Class::classRedefinedCount(the_class_mirror), 3327 os::available_memory() >> 10)); 3328 3329 RC_TIMER_STOP(_timer_rsc_phase2); 3330 } // end redefine_single_class() 3331 3332 3333 // Increment the classRedefinedCount field in the specific instanceKlass 3334 // and in all direct and indirect subclasses. 3335 void VM_RedefineClasses::increment_class_counter(instanceKlass *ik, TRAPS) { 3336 oop class_mirror = ik->java_mirror(); 3337 klassOop class_oop = java_lang_Class::as_klassOop(class_mirror); 3338 int new_count = java_lang_Class::classRedefinedCount(class_mirror) + 1; 3339 java_lang_Class::set_classRedefinedCount(class_mirror, new_count); 3340 3341 if (class_oop != _the_class_oop) { 3342 // _the_class_oop count is printed at end of redefine_single_class() 3343 RC_TRACE_WITH_THREAD(0x00000008, THREAD, 3344 ("updated count in subclass=%s to %d", ik->external_name(), new_count)); 3345 } 3346 3347 for (Klass *subk = ik->subklass(); subk != NULL; 3348 subk = subk->next_sibling()) { 3349 if (subk->oop_is_instance()) { 3350 // Only update instanceKlasses 3351 instanceKlass *subik = (instanceKlass*)subk; 3352 // recursively do subclasses of the current subclass 3353 increment_class_counter(subik, THREAD); 3354 } 3355 } 3356 } 3357 3358 #ifndef PRODUCT 3359 void VM_RedefineClasses::check_class(klassOop k_oop, 3360 oop initiating_loader, TRAPS) { 3361 Klass *k = k_oop->klass_part(); 3362 if (k->oop_is_instance()) { 3363 HandleMark hm(THREAD); 3364 instanceKlass *ik = (instanceKlass *) k; 3365 3366 if (ik->vtable_length() > 0) { 3367 ResourceMark rm(THREAD); 3368 if (!ik->vtable()->check_no_old_entries()) { 3369 tty->print_cr("klassVtable::check_no_old_entries failure -- OLD method found -- class: %s", ik->signature_name()); 3370 ik->vtable()->dump_vtable(); 3371 dump_methods(); 3372 assert(false, "OLD method found"); 3373 } 3374 } 3375 } 3376 } 3377 3378 void VM_RedefineClasses::dump_methods() { 3379 int j; 3380 tty->print_cr("_old_methods --"); 3381 for (j = 0; j < _old_methods->length(); ++j) { 3382 methodOop m = (methodOop) _old_methods->obj_at(j); 3383 tty->print("%4d (%5d) ", j, m->vtable_index()); 3384 m->access_flags().print_on(tty); 3385 tty->print(" -- "); 3386 m->print_name(tty); 3387 tty->cr(); 3388 } 3389 tty->print_cr("_new_methods --"); 3390 for (j = 0; j < _new_methods->length(); ++j) { 3391 methodOop m = (methodOop) _new_methods->obj_at(j); 3392 tty->print("%4d (%5d) ", j, m->vtable_index()); 3393 m->access_flags().print_on(tty); 3394 tty->print(" -- "); 3395 m->print_name(tty); 3396 tty->cr(); 3397 } 3398 tty->print_cr("_matching_(old/new)_methods --"); 3399 for (j = 0; j < _matching_methods_length; ++j) { 3400 methodOop m = _matching_old_methods[j]; 3401 tty->print("%4d (%5d) ", j, m->vtable_index()); 3402 m->access_flags().print_on(tty); 3403 tty->print(" -- "); 3404 m->print_name(tty); 3405 tty->cr(); 3406 m = _matching_new_methods[j]; 3407 tty->print(" (%5d) ", m->vtable_index()); 3408 m->access_flags().print_on(tty); 3409 tty->cr(); 3410 } 3411 tty->print_cr("_deleted_methods --"); 3412 for (j = 0; j < _deleted_methods_length; ++j) { 3413 methodOop m = _deleted_methods[j]; 3414 tty->print("%4d (%5d) ", j, m->vtable_index()); 3415 m->access_flags().print_on(tty); 3416 tty->print(" -- "); 3417 m->print_name(tty); 3418 tty->cr(); 3419 } 3420 tty->print_cr("_added_methods --"); 3421 for (j = 0; j < _added_methods_length; ++j) { 3422 methodOop m = _added_methods[j]; 3423 tty->print("%4d (%5d) ", j, m->vtable_index()); 3424 m->access_flags().print_on(tty); 3425 tty->print(" -- "); 3426 m->print_name(tty); 3427 tty->cr(); 3428 } 3429 } 3430 #endif