jvmtiRedefineClasses.cpp revision 1879:f95d63e2154a
1/* 2 * Copyright (c) 2003, 2010, 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/klassVtable.hpp" 34#include "prims/jvmtiImpl.hpp" 35#include "prims/jvmtiRedefineClasses.hpp" 36#include "prims/methodComparator.hpp" 37#include "runtime/deoptimization.hpp" 38#include "runtime/relocator.hpp" 39#include "utilities/bitMap.inline.hpp" 40 41 42objArrayOop VM_RedefineClasses::_old_methods = NULL; 43objArrayOop VM_RedefineClasses::_new_methods = NULL; 44methodOop* VM_RedefineClasses::_matching_old_methods = NULL; 45methodOop* VM_RedefineClasses::_matching_new_methods = NULL; 46methodOop* VM_RedefineClasses::_deleted_methods = NULL; 47methodOop* VM_RedefineClasses::_added_methods = NULL; 48int VM_RedefineClasses::_matching_methods_length = 0; 49int VM_RedefineClasses::_deleted_methods_length = 0; 50int VM_RedefineClasses::_added_methods_length = 0; 51klassOop VM_RedefineClasses::_the_class_oop = NULL; 52 53 54VM_RedefineClasses::VM_RedefineClasses(jint class_count, 55 const jvmtiClassDefinition *class_defs, 56 JvmtiClassLoadKind class_load_kind) { 57 _class_count = class_count; 58 _class_defs = class_defs; 59 _class_load_kind = class_load_kind; 60 _res = JVMTI_ERROR_NONE; 61} 62 63bool VM_RedefineClasses::doit_prologue() { 64 if (_class_count == 0) { 65 _res = JVMTI_ERROR_NONE; 66 return false; 67 } 68 if (_class_defs == NULL) { 69 _res = JVMTI_ERROR_NULL_POINTER; 70 return false; 71 } 72 for (int i = 0; i < _class_count; i++) { 73 if (_class_defs[i].klass == NULL) { 74 _res = JVMTI_ERROR_INVALID_CLASS; 75 return false; 76 } 77 if (_class_defs[i].class_byte_count == 0) { 78 _res = JVMTI_ERROR_INVALID_CLASS_FORMAT; 79 return false; 80 } 81 if (_class_defs[i].class_bytes == NULL) { 82 _res = JVMTI_ERROR_NULL_POINTER; 83 return false; 84 } 85 } 86 87 // Start timer after all the sanity checks; not quite accurate, but 88 // better than adding a bunch of stop() calls. 89 RC_TIMER_START(_timer_vm_op_prologue); 90 91 // We first load new class versions in the prologue, because somewhere down the 92 // call chain it is required that the current thread is a Java thread. 93 _res = load_new_class_versions(Thread::current()); 94 if (_res != JVMTI_ERROR_NONE) { 95 // Free os::malloc allocated memory in load_new_class_version. 96 os::free(_scratch_classes); 97 RC_TIMER_STOP(_timer_vm_op_prologue); 98 return false; 99 } 100 101 RC_TIMER_STOP(_timer_vm_op_prologue); 102 return true; 103} 104 105void VM_RedefineClasses::doit() { 106 Thread *thread = Thread::current(); 107 108 if (UseSharedSpaces) { 109 // Sharing is enabled so we remap the shared readonly space to 110 // shared readwrite, private just in case we need to redefine 111 // a shared class. We do the remap during the doit() phase of 112 // the safepoint to be safer. 113 if (!CompactingPermGenGen::remap_shared_readonly_as_readwrite()) { 114 RC_TRACE_WITH_THREAD(0x00000001, thread, 115 ("failed to remap shared readonly space to readwrite, private")); 116 _res = JVMTI_ERROR_INTERNAL; 117 return; 118 } 119 } 120 121 for (int i = 0; i < _class_count; i++) { 122 redefine_single_class(_class_defs[i].klass, _scratch_classes[i], thread); 123 } 124 // Disable any dependent concurrent compilations 125 SystemDictionary::notice_modification(); 126 127 // Set flag indicating that some invariants are no longer true. 128 // See jvmtiExport.hpp for detailed explanation. 129 JvmtiExport::set_has_redefined_a_class(); 130 131#ifdef ASSERT 132 SystemDictionary::classes_do(check_class, thread); 133#endif 134} 135 136void VM_RedefineClasses::doit_epilogue() { 137 // Free os::malloc allocated memory. 138 // The memory allocated in redefine will be free'ed in next VM operation. 139 os::free(_scratch_classes); 140 141 if (RC_TRACE_ENABLED(0x00000004)) { 142 // Used to have separate timers for "doit" and "all", but the timer 143 // overhead skewed the measurements. 144 jlong doit_time = _timer_rsc_phase1.milliseconds() + 145 _timer_rsc_phase2.milliseconds(); 146 jlong all_time = _timer_vm_op_prologue.milliseconds() + doit_time; 147 148 RC_TRACE(0x00000004, ("vm_op: all=" UINT64_FORMAT 149 " prologue=" UINT64_FORMAT " doit=" UINT64_FORMAT, all_time, 150 _timer_vm_op_prologue.milliseconds(), doit_time)); 151 RC_TRACE(0x00000004, 152 ("redefine_single_class: phase1=" UINT64_FORMAT " phase2=" UINT64_FORMAT, 153 _timer_rsc_phase1.milliseconds(), _timer_rsc_phase2.milliseconds())); 154 } 155} 156 157bool VM_RedefineClasses::is_modifiable_class(oop klass_mirror) { 158 // classes for primitives cannot be redefined 159 if (java_lang_Class::is_primitive(klass_mirror)) { 160 return false; 161 } 162 klassOop the_class_oop = java_lang_Class::as_klassOop(klass_mirror); 163 // classes for arrays cannot be redefined 164 if (the_class_oop == NULL || !Klass::cast(the_class_oop)->oop_is_instance()) { 165 return false; 166 } 167 return true; 168} 169 170// Append the current entry at scratch_i in scratch_cp to *merge_cp_p 171// where the end of *merge_cp_p is specified by *merge_cp_length_p. For 172// direct CP entries, there is just the current entry to append. For 173// indirect and double-indirect CP entries, there are zero or more 174// referenced CP entries along with the current entry to append. 175// Indirect and double-indirect CP entries are handled by recursive 176// calls to append_entry() as needed. The referenced CP entries are 177// always appended to *merge_cp_p before the referee CP entry. These 178// referenced CP entries may already exist in *merge_cp_p in which case 179// there is nothing extra to append and only the current entry is 180// appended. 181void VM_RedefineClasses::append_entry(constantPoolHandle scratch_cp, 182 int scratch_i, constantPoolHandle *merge_cp_p, int *merge_cp_length_p, 183 TRAPS) { 184 185 // append is different depending on entry tag type 186 switch (scratch_cp->tag_at(scratch_i).value()) { 187 188 // The old verifier is implemented outside the VM. It loads classes, 189 // but does not resolve constant pool entries directly so we never 190 // see Class entries here with the old verifier. Similarly the old 191 // verifier does not like Class entries in the input constant pool. 192 // The split-verifier is implemented in the VM so it can optionally 193 // and directly resolve constant pool entries to load classes. The 194 // split-verifier can accept either Class entries or UnresolvedClass 195 // entries in the input constant pool. We revert the appended copy 196 // back to UnresolvedClass so that either verifier will be happy 197 // with the constant pool entry. 198 case JVM_CONSTANT_Class: 199 { 200 // revert the copy to JVM_CONSTANT_UnresolvedClass 201 (*merge_cp_p)->unresolved_klass_at_put(*merge_cp_length_p, 202 scratch_cp->klass_name_at(scratch_i)); 203 204 if (scratch_i != *merge_cp_length_p) { 205 // The new entry in *merge_cp_p is at a different index than 206 // the new entry in scratch_cp so we need to map the index values. 207 map_index(scratch_cp, scratch_i, *merge_cp_length_p); 208 } 209 (*merge_cp_length_p)++; 210 } break; 211 212 // these are direct CP entries so they can be directly appended, 213 // but double and long take two constant pool entries 214 case JVM_CONSTANT_Double: // fall through 215 case JVM_CONSTANT_Long: 216 { 217 scratch_cp->copy_entry_to(scratch_i, *merge_cp_p, *merge_cp_length_p, 218 THREAD); 219 220 if (scratch_i != *merge_cp_length_p) { 221 // The new entry in *merge_cp_p is at a different index than 222 // the new entry in scratch_cp so we need to map the index values. 223 map_index(scratch_cp, scratch_i, *merge_cp_length_p); 224 } 225 (*merge_cp_length_p) += 2; 226 } break; 227 228 // these are direct CP entries so they can be directly appended 229 case JVM_CONSTANT_Float: // fall through 230 case JVM_CONSTANT_Integer: // fall through 231 case JVM_CONSTANT_Utf8: // fall through 232 233 // This was an indirect CP entry, but it has been changed into 234 // an interned string so this entry can be directly appended. 235 case JVM_CONSTANT_String: // fall through 236 237 // These were indirect CP entries, but they have been changed into 238 // symbolOops so these entries can be directly appended. 239 case JVM_CONSTANT_UnresolvedClass: // fall through 240 case JVM_CONSTANT_UnresolvedString: 241 { 242 scratch_cp->copy_entry_to(scratch_i, *merge_cp_p, *merge_cp_length_p, 243 THREAD); 244 245 if (scratch_i != *merge_cp_length_p) { 246 // The new entry in *merge_cp_p is at a different index than 247 // the new entry in scratch_cp so we need to map the index values. 248 map_index(scratch_cp, scratch_i, *merge_cp_length_p); 249 } 250 (*merge_cp_length_p)++; 251 } break; 252 253 // this is an indirect CP entry so it needs special handling 254 case JVM_CONSTANT_NameAndType: 255 { 256 int name_ref_i = scratch_cp->name_ref_index_at(scratch_i); 257 int new_name_ref_i = 0; 258 bool match = (name_ref_i < *merge_cp_length_p) && 259 scratch_cp->compare_entry_to(name_ref_i, *merge_cp_p, name_ref_i, 260 THREAD); 261 if (!match) { 262 // forward reference in *merge_cp_p or not a direct match 263 264 int found_i = scratch_cp->find_matching_entry(name_ref_i, *merge_cp_p, 265 THREAD); 266 if (found_i != 0) { 267 guarantee(found_i != name_ref_i, 268 "compare_entry_to() and find_matching_entry() do not agree"); 269 270 // Found a matching entry somewhere else in *merge_cp_p so 271 // just need a mapping entry. 272 new_name_ref_i = found_i; 273 map_index(scratch_cp, name_ref_i, found_i); 274 } else { 275 // no match found so we have to append this entry to *merge_cp_p 276 append_entry(scratch_cp, name_ref_i, merge_cp_p, merge_cp_length_p, 277 THREAD); 278 // The above call to append_entry() can only append one entry 279 // so the post call query of *merge_cp_length_p is only for 280 // the sake of consistency. 281 new_name_ref_i = *merge_cp_length_p - 1; 282 } 283 } 284 285 int signature_ref_i = scratch_cp->signature_ref_index_at(scratch_i); 286 int new_signature_ref_i = 0; 287 match = (signature_ref_i < *merge_cp_length_p) && 288 scratch_cp->compare_entry_to(signature_ref_i, *merge_cp_p, 289 signature_ref_i, THREAD); 290 if (!match) { 291 // forward reference in *merge_cp_p or not a direct match 292 293 int found_i = scratch_cp->find_matching_entry(signature_ref_i, 294 *merge_cp_p, THREAD); 295 if (found_i != 0) { 296 guarantee(found_i != signature_ref_i, 297 "compare_entry_to() and find_matching_entry() do not agree"); 298 299 // Found a matching entry somewhere else in *merge_cp_p so 300 // just need a mapping entry. 301 new_signature_ref_i = found_i; 302 map_index(scratch_cp, signature_ref_i, found_i); 303 } else { 304 // no match found so we have to append this entry to *merge_cp_p 305 append_entry(scratch_cp, signature_ref_i, merge_cp_p, 306 merge_cp_length_p, THREAD); 307 // The above call to append_entry() can only append one entry 308 // so the post call query of *merge_cp_length_p is only for 309 // the sake of consistency. 310 new_signature_ref_i = *merge_cp_length_p - 1; 311 } 312 } 313 314 // If the referenced entries already exist in *merge_cp_p, then 315 // both new_name_ref_i and new_signature_ref_i will both be 0. 316 // In that case, all we are appending is the current entry. 317 if (new_name_ref_i == 0) { 318 new_name_ref_i = name_ref_i; 319 } else { 320 RC_TRACE(0x00080000, 321 ("NameAndType entry@%d name_ref_index change: %d to %d", 322 *merge_cp_length_p, name_ref_i, new_name_ref_i)); 323 } 324 if (new_signature_ref_i == 0) { 325 new_signature_ref_i = signature_ref_i; 326 } else { 327 RC_TRACE(0x00080000, 328 ("NameAndType entry@%d signature_ref_index change: %d to %d", 329 *merge_cp_length_p, signature_ref_i, new_signature_ref_i)); 330 } 331 332 (*merge_cp_p)->name_and_type_at_put(*merge_cp_length_p, 333 new_name_ref_i, new_signature_ref_i); 334 if (scratch_i != *merge_cp_length_p) { 335 // The new entry in *merge_cp_p is at a different index than 336 // the new entry in scratch_cp so we need to map the index values. 337 map_index(scratch_cp, scratch_i, *merge_cp_length_p); 338 } 339 (*merge_cp_length_p)++; 340 } break; 341 342 // this is a double-indirect CP entry so it needs special handling 343 case JVM_CONSTANT_Fieldref: // fall through 344 case JVM_CONSTANT_InterfaceMethodref: // fall through 345 case JVM_CONSTANT_Methodref: 346 { 347 int klass_ref_i = scratch_cp->uncached_klass_ref_index_at(scratch_i); 348 int new_klass_ref_i = 0; 349 bool match = (klass_ref_i < *merge_cp_length_p) && 350 scratch_cp->compare_entry_to(klass_ref_i, *merge_cp_p, klass_ref_i, 351 THREAD); 352 if (!match) { 353 // forward reference in *merge_cp_p or not a direct match 354 355 int found_i = scratch_cp->find_matching_entry(klass_ref_i, *merge_cp_p, 356 THREAD); 357 if (found_i != 0) { 358 guarantee(found_i != klass_ref_i, 359 "compare_entry_to() and find_matching_entry() do not agree"); 360 361 // Found a matching entry somewhere else in *merge_cp_p so 362 // just need a mapping entry. 363 new_klass_ref_i = found_i; 364 map_index(scratch_cp, klass_ref_i, found_i); 365 } else { 366 // no match found so we have to append this entry to *merge_cp_p 367 append_entry(scratch_cp, klass_ref_i, merge_cp_p, merge_cp_length_p, 368 THREAD); 369 // The above call to append_entry() can only append one entry 370 // so the post call query of *merge_cp_length_p is only for 371 // the sake of consistency. Without the optimization where we 372 // use JVM_CONSTANT_UnresolvedClass, then up to two entries 373 // could be appended. 374 new_klass_ref_i = *merge_cp_length_p - 1; 375 } 376 } 377 378 int name_and_type_ref_i = 379 scratch_cp->uncached_name_and_type_ref_index_at(scratch_i); 380 int new_name_and_type_ref_i = 0; 381 match = (name_and_type_ref_i < *merge_cp_length_p) && 382 scratch_cp->compare_entry_to(name_and_type_ref_i, *merge_cp_p, 383 name_and_type_ref_i, THREAD); 384 if (!match) { 385 // forward reference in *merge_cp_p or not a direct match 386 387 int found_i = scratch_cp->find_matching_entry(name_and_type_ref_i, 388 *merge_cp_p, THREAD); 389 if (found_i != 0) { 390 guarantee(found_i != name_and_type_ref_i, 391 "compare_entry_to() and find_matching_entry() do not agree"); 392 393 // Found a matching entry somewhere else in *merge_cp_p so 394 // just need a mapping entry. 395 new_name_and_type_ref_i = found_i; 396 map_index(scratch_cp, name_and_type_ref_i, found_i); 397 } else { 398 // no match found so we have to append this entry to *merge_cp_p 399 append_entry(scratch_cp, name_and_type_ref_i, merge_cp_p, 400 merge_cp_length_p, THREAD); 401 // The above call to append_entry() can append more than 402 // one entry so the post call query of *merge_cp_length_p 403 // is required in order to get the right index for the 404 // JVM_CONSTANT_NameAndType entry. 405 new_name_and_type_ref_i = *merge_cp_length_p - 1; 406 } 407 } 408 409 // If the referenced entries already exist in *merge_cp_p, then 410 // both new_klass_ref_i and new_name_and_type_ref_i will both be 411 // 0. In that case, all we are appending is the current entry. 412 if (new_klass_ref_i == 0) { 413 new_klass_ref_i = klass_ref_i; 414 } 415 if (new_name_and_type_ref_i == 0) { 416 new_name_and_type_ref_i = name_and_type_ref_i; 417 } 418 419 const char *entry_name; 420 switch (scratch_cp->tag_at(scratch_i).value()) { 421 case JVM_CONSTANT_Fieldref: 422 entry_name = "Fieldref"; 423 (*merge_cp_p)->field_at_put(*merge_cp_length_p, new_klass_ref_i, 424 new_name_and_type_ref_i); 425 break; 426 case JVM_CONSTANT_InterfaceMethodref: 427 entry_name = "IFMethodref"; 428 (*merge_cp_p)->interface_method_at_put(*merge_cp_length_p, 429 new_klass_ref_i, new_name_and_type_ref_i); 430 break; 431 case JVM_CONSTANT_Methodref: 432 entry_name = "Methodref"; 433 (*merge_cp_p)->method_at_put(*merge_cp_length_p, new_klass_ref_i, 434 new_name_and_type_ref_i); 435 break; 436 default: 437 guarantee(false, "bad switch"); 438 break; 439 } 440 441 if (klass_ref_i != new_klass_ref_i) { 442 RC_TRACE(0x00080000, ("%s entry@%d class_index changed: %d to %d", 443 entry_name, *merge_cp_length_p, klass_ref_i, new_klass_ref_i)); 444 } 445 if (name_and_type_ref_i != new_name_and_type_ref_i) { 446 RC_TRACE(0x00080000, 447 ("%s entry@%d name_and_type_index changed: %d to %d", 448 entry_name, *merge_cp_length_p, name_and_type_ref_i, 449 new_name_and_type_ref_i)); 450 } 451 452 if (scratch_i != *merge_cp_length_p) { 453 // The new entry in *merge_cp_p is at a different index than 454 // the new entry in scratch_cp so we need to map the index values. 455 map_index(scratch_cp, scratch_i, *merge_cp_length_p); 456 } 457 (*merge_cp_length_p)++; 458 } break; 459 460 // At this stage, Class or UnresolvedClass could be here, but not 461 // ClassIndex 462 case JVM_CONSTANT_ClassIndex: // fall through 463 464 // Invalid is used as the tag for the second constant pool entry 465 // occupied by JVM_CONSTANT_Double or JVM_CONSTANT_Long. It should 466 // not be seen by itself. 467 case JVM_CONSTANT_Invalid: // fall through 468 469 // At this stage, String or UnresolvedString could be here, but not 470 // StringIndex 471 case JVM_CONSTANT_StringIndex: // fall through 472 473 // At this stage JVM_CONSTANT_UnresolvedClassInError should not be 474 // here 475 case JVM_CONSTANT_UnresolvedClassInError: // fall through 476 477 default: 478 { 479 // leave a breadcrumb 480 jbyte bad_value = scratch_cp->tag_at(scratch_i).value(); 481 ShouldNotReachHere(); 482 } break; 483 } // end switch tag value 484} // end append_entry() 485 486 487void VM_RedefineClasses::swap_all_method_annotations(int i, int j, instanceKlassHandle scratch_class) { 488 typeArrayOop save; 489 490 save = scratch_class->get_method_annotations_of(i); 491 scratch_class->set_method_annotations_of(i, scratch_class->get_method_annotations_of(j)); 492 scratch_class->set_method_annotations_of(j, save); 493 494 save = scratch_class->get_method_parameter_annotations_of(i); 495 scratch_class->set_method_parameter_annotations_of(i, scratch_class->get_method_parameter_annotations_of(j)); 496 scratch_class->set_method_parameter_annotations_of(j, save); 497 498 save = scratch_class->get_method_default_annotations_of(i); 499 scratch_class->set_method_default_annotations_of(i, scratch_class->get_method_default_annotations_of(j)); 500 scratch_class->set_method_default_annotations_of(j, save); 501} 502 503 504jvmtiError VM_RedefineClasses::compare_and_normalize_class_versions( 505 instanceKlassHandle the_class, 506 instanceKlassHandle scratch_class) { 507 int i; 508 509 // Check superclasses, or rather their names, since superclasses themselves can be 510 // requested to replace. 511 // Check for NULL superclass first since this might be java.lang.Object 512 if (the_class->super() != scratch_class->super() && 513 (the_class->super() == NULL || scratch_class->super() == NULL || 514 Klass::cast(the_class->super())->name() != 515 Klass::cast(scratch_class->super())->name())) { 516 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_HIERARCHY_CHANGED; 517 } 518 519 // Check if the number, names and order of directly implemented interfaces are the same. 520 // I think in principle we should just check if the sets of names of directly implemented 521 // interfaces are the same, i.e. the order of declaration (which, however, if changed in the 522 // .java file, also changes in .class file) should not matter. However, comparing sets is 523 // technically a bit more difficult, and, more importantly, I am not sure at present that the 524 // order of interfaces does not matter on the implementation level, i.e. that the VM does not 525 // rely on it somewhere. 526 objArrayOop k_interfaces = the_class->local_interfaces(); 527 objArrayOop k_new_interfaces = scratch_class->local_interfaces(); 528 int n_intfs = k_interfaces->length(); 529 if (n_intfs != k_new_interfaces->length()) { 530 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_HIERARCHY_CHANGED; 531 } 532 for (i = 0; i < n_intfs; i++) { 533 if (Klass::cast((klassOop) k_interfaces->obj_at(i))->name() != 534 Klass::cast((klassOop) k_new_interfaces->obj_at(i))->name()) { 535 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_HIERARCHY_CHANGED; 536 } 537 } 538 539 // Check whether class is in the error init state. 540 if (the_class->is_in_error_state()) { 541 // TBD #5057930: special error code is needed in 1.6 542 return JVMTI_ERROR_INVALID_CLASS; 543 } 544 545 // Check whether class modifiers are the same. 546 jushort old_flags = (jushort) the_class->access_flags().get_flags(); 547 jushort new_flags = (jushort) scratch_class->access_flags().get_flags(); 548 if (old_flags != new_flags) { 549 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_CLASS_MODIFIERS_CHANGED; 550 } 551 552 // Check if the number, names, types and order of fields declared in these classes 553 // are the same. 554 typeArrayOop k_old_fields = the_class->fields(); 555 typeArrayOop k_new_fields = scratch_class->fields(); 556 int n_fields = k_old_fields->length(); 557 if (n_fields != k_new_fields->length()) { 558 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_SCHEMA_CHANGED; 559 } 560 561 for (i = 0; i < n_fields; i += instanceKlass::next_offset) { 562 // access 563 old_flags = k_old_fields->ushort_at(i + instanceKlass::access_flags_offset); 564 new_flags = k_new_fields->ushort_at(i + instanceKlass::access_flags_offset); 565 if ((old_flags ^ new_flags) & JVM_RECOGNIZED_FIELD_MODIFIERS) { 566 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_SCHEMA_CHANGED; 567 } 568 // offset 569 if (k_old_fields->short_at(i + instanceKlass::low_offset) != 570 k_new_fields->short_at(i + instanceKlass::low_offset) || 571 k_old_fields->short_at(i + instanceKlass::high_offset) != 572 k_new_fields->short_at(i + instanceKlass::high_offset)) { 573 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_SCHEMA_CHANGED; 574 } 575 // name and signature 576 jshort name_index = k_old_fields->short_at(i + instanceKlass::name_index_offset); 577 jshort sig_index = k_old_fields->short_at(i +instanceKlass::signature_index_offset); 578 symbolOop name_sym1 = the_class->constants()->symbol_at(name_index); 579 symbolOop sig_sym1 = the_class->constants()->symbol_at(sig_index); 580 name_index = k_new_fields->short_at(i + instanceKlass::name_index_offset); 581 sig_index = k_new_fields->short_at(i + instanceKlass::signature_index_offset); 582 symbolOop name_sym2 = scratch_class->constants()->symbol_at(name_index); 583 symbolOop sig_sym2 = scratch_class->constants()->symbol_at(sig_index); 584 if (name_sym1 != name_sym2 || sig_sym1 != sig_sym2) { 585 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_SCHEMA_CHANGED; 586 } 587 } 588 589 // Do a parallel walk through the old and new methods. Detect 590 // cases where they match (exist in both), have been added in 591 // the new methods, or have been deleted (exist only in the 592 // old methods). The class file parser places methods in order 593 // by method name, but does not order overloaded methods by 594 // signature. In order to determine what fate befell the methods, 595 // this code places the overloaded new methods that have matching 596 // old methods in the same order as the old methods and places 597 // new overloaded methods at the end of overloaded methods of 598 // that name. The code for this order normalization is adapted 599 // from the algorithm used in instanceKlass::find_method(). 600 // Since we are swapping out of order entries as we find them, 601 // we only have to search forward through the overloaded methods. 602 // Methods which are added and have the same name as an existing 603 // method (but different signature) will be put at the end of 604 // the methods with that name, and the name mismatch code will 605 // handle them. 606 objArrayHandle k_old_methods(the_class->methods()); 607 objArrayHandle k_new_methods(scratch_class->methods()); 608 int n_old_methods = k_old_methods->length(); 609 int n_new_methods = k_new_methods->length(); 610 611 int ni = 0; 612 int oi = 0; 613 while (true) { 614 methodOop k_old_method; 615 methodOop k_new_method; 616 enum { matched, added, deleted, undetermined } method_was = undetermined; 617 618 if (oi >= n_old_methods) { 619 if (ni >= n_new_methods) { 620 break; // we've looked at everything, done 621 } 622 // New method at the end 623 k_new_method = (methodOop) k_new_methods->obj_at(ni); 624 method_was = added; 625 } else if (ni >= n_new_methods) { 626 // Old method, at the end, is deleted 627 k_old_method = (methodOop) k_old_methods->obj_at(oi); 628 method_was = deleted; 629 } else { 630 // There are more methods in both the old and new lists 631 k_old_method = (methodOop) k_old_methods->obj_at(oi); 632 k_new_method = (methodOop) k_new_methods->obj_at(ni); 633 if (k_old_method->name() != k_new_method->name()) { 634 // Methods are sorted by method name, so a mismatch means added 635 // or deleted 636 if (k_old_method->name()->fast_compare(k_new_method->name()) > 0) { 637 method_was = added; 638 } else { 639 method_was = deleted; 640 } 641 } else if (k_old_method->signature() == k_new_method->signature()) { 642 // Both the name and signature match 643 method_was = matched; 644 } else { 645 // The name matches, but the signature doesn't, which means we have to 646 // search forward through the new overloaded methods. 647 int nj; // outside the loop for post-loop check 648 for (nj = ni + 1; nj < n_new_methods; nj++) { 649 methodOop m = (methodOop)k_new_methods->obj_at(nj); 650 if (k_old_method->name() != m->name()) { 651 // reached another method name so no more overloaded methods 652 method_was = deleted; 653 break; 654 } 655 if (k_old_method->signature() == m->signature()) { 656 // found a match so swap the methods 657 k_new_methods->obj_at_put(ni, m); 658 k_new_methods->obj_at_put(nj, k_new_method); 659 k_new_method = m; 660 method_was = matched; 661 break; 662 } 663 } 664 665 if (nj >= n_new_methods) { 666 // reached the end without a match; so method was deleted 667 method_was = deleted; 668 } 669 } 670 } 671 672 switch (method_was) { 673 case matched: 674 // methods match, be sure modifiers do too 675 old_flags = (jushort) k_old_method->access_flags().get_flags(); 676 new_flags = (jushort) k_new_method->access_flags().get_flags(); 677 if ((old_flags ^ new_flags) & ~(JVM_ACC_NATIVE)) { 678 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_METHOD_MODIFIERS_CHANGED; 679 } 680 { 681 u2 new_num = k_new_method->method_idnum(); 682 u2 old_num = k_old_method->method_idnum(); 683 if (new_num != old_num) { 684 methodOop idnum_owner = scratch_class->method_with_idnum(old_num); 685 if (idnum_owner != NULL) { 686 // There is already a method assigned this idnum -- switch them 687 idnum_owner->set_method_idnum(new_num); 688 } 689 k_new_method->set_method_idnum(old_num); 690 swap_all_method_annotations(old_num, new_num, scratch_class); 691 } 692 } 693 RC_TRACE(0x00008000, ("Method matched: new: %s [%d] == old: %s [%d]", 694 k_new_method->name_and_sig_as_C_string(), ni, 695 k_old_method->name_and_sig_as_C_string(), oi)); 696 // advance to next pair of methods 697 ++oi; 698 ++ni; 699 break; 700 case added: 701 // method added, see if it is OK 702 new_flags = (jushort) k_new_method->access_flags().get_flags(); 703 if ((new_flags & JVM_ACC_PRIVATE) == 0 704 // hack: private should be treated as final, but alas 705 || (new_flags & (JVM_ACC_FINAL|JVM_ACC_STATIC)) == 0 706 ) { 707 // new methods must be private 708 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_METHOD_ADDED; 709 } 710 { 711 u2 num = the_class->next_method_idnum(); 712 if (num == constMethodOopDesc::UNSET_IDNUM) { 713 // cannot add any more methods 714 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_METHOD_ADDED; 715 } 716 u2 new_num = k_new_method->method_idnum(); 717 methodOop idnum_owner = scratch_class->method_with_idnum(num); 718 if (idnum_owner != NULL) { 719 // There is already a method assigned this idnum -- switch them 720 idnum_owner->set_method_idnum(new_num); 721 } 722 k_new_method->set_method_idnum(num); 723 swap_all_method_annotations(new_num, num, scratch_class); 724 } 725 RC_TRACE(0x00008000, ("Method added: new: %s [%d]", 726 k_new_method->name_and_sig_as_C_string(), ni)); 727 ++ni; // advance to next new method 728 break; 729 case deleted: 730 // method deleted, see if it is OK 731 old_flags = (jushort) k_old_method->access_flags().get_flags(); 732 if ((old_flags & JVM_ACC_PRIVATE) == 0 733 // hack: private should be treated as final, but alas 734 || (old_flags & (JVM_ACC_FINAL|JVM_ACC_STATIC)) == 0 735 ) { 736 // deleted methods must be private 737 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_METHOD_DELETED; 738 } 739 RC_TRACE(0x00008000, ("Method deleted: old: %s [%d]", 740 k_old_method->name_and_sig_as_C_string(), oi)); 741 ++oi; // advance to next old method 742 break; 743 default: 744 ShouldNotReachHere(); 745 } 746 } 747 748 return JVMTI_ERROR_NONE; 749} 750 751 752// Find new constant pool index value for old constant pool index value 753// by seaching the index map. Returns zero (0) if there is no mapped 754// value for the old constant pool index. 755int VM_RedefineClasses::find_new_index(int old_index) { 756 if (_index_map_count == 0) { 757 // map is empty so nothing can be found 758 return 0; 759 } 760 761 if (old_index < 1 || old_index >= _index_map_p->length()) { 762 // The old_index is out of range so it is not mapped. This should 763 // not happen in regular constant pool merging use, but it can 764 // happen if a corrupt annotation is processed. 765 return 0; 766 } 767 768 int value = _index_map_p->at(old_index); 769 if (value == -1) { 770 // the old_index is not mapped 771 return 0; 772 } 773 774 return value; 775} // end find_new_index() 776 777 778// Returns true if the current mismatch is due to a resolved/unresolved 779// class pair. Otherwise, returns false. 780bool VM_RedefineClasses::is_unresolved_class_mismatch(constantPoolHandle cp1, 781 int index1, constantPoolHandle cp2, int index2) { 782 783 jbyte t1 = cp1->tag_at(index1).value(); 784 if (t1 != JVM_CONSTANT_Class && t1 != JVM_CONSTANT_UnresolvedClass) { 785 return false; // wrong entry type; not our special case 786 } 787 788 jbyte t2 = cp2->tag_at(index2).value(); 789 if (t2 != JVM_CONSTANT_Class && t2 != JVM_CONSTANT_UnresolvedClass) { 790 return false; // wrong entry type; not our special case 791 } 792 793 if (t1 == t2) { 794 return false; // not a mismatch; not our special case 795 } 796 797 char *s1 = cp1->klass_name_at(index1)->as_C_string(); 798 char *s2 = cp2->klass_name_at(index2)->as_C_string(); 799 if (strcmp(s1, s2) != 0) { 800 return false; // strings don't match; not our special case 801 } 802 803 return true; // made it through the gauntlet; this is our special case 804} // end is_unresolved_class_mismatch() 805 806 807// Returns true if the current mismatch is due to a resolved/unresolved 808// string pair. Otherwise, returns false. 809bool VM_RedefineClasses::is_unresolved_string_mismatch(constantPoolHandle cp1, 810 int index1, constantPoolHandle cp2, int index2) { 811 812 jbyte t1 = cp1->tag_at(index1).value(); 813 if (t1 != JVM_CONSTANT_String && t1 != JVM_CONSTANT_UnresolvedString) { 814 return false; // wrong entry type; not our special case 815 } 816 817 jbyte t2 = cp2->tag_at(index2).value(); 818 if (t2 != JVM_CONSTANT_String && t2 != JVM_CONSTANT_UnresolvedString) { 819 return false; // wrong entry type; not our special case 820 } 821 822 if (t1 == t2) { 823 return false; // not a mismatch; not our special case 824 } 825 826 char *s1 = cp1->string_at_noresolve(index1); 827 char *s2 = cp2->string_at_noresolve(index2); 828 if (strcmp(s1, s2) != 0) { 829 return false; // strings don't match; not our special case 830 } 831 832 return true; // made it through the gauntlet; this is our special case 833} // end is_unresolved_string_mismatch() 834 835 836jvmtiError VM_RedefineClasses::load_new_class_versions(TRAPS) { 837 // For consistency allocate memory using os::malloc wrapper. 838 _scratch_classes = (instanceKlassHandle *) 839 os::malloc(sizeof(instanceKlassHandle) * _class_count); 840 if (_scratch_classes == NULL) { 841 return JVMTI_ERROR_OUT_OF_MEMORY; 842 } 843 844 ResourceMark rm(THREAD); 845 846 JvmtiThreadState *state = JvmtiThreadState::state_for(JavaThread::current()); 847 // state can only be NULL if the current thread is exiting which 848 // should not happen since we're trying to do a RedefineClasses 849 guarantee(state != NULL, "exiting thread calling load_new_class_versions"); 850 for (int i = 0; i < _class_count; i++) { 851 oop mirror = JNIHandles::resolve_non_null(_class_defs[i].klass); 852 // classes for primitives cannot be redefined 853 if (!is_modifiable_class(mirror)) { 854 return JVMTI_ERROR_UNMODIFIABLE_CLASS; 855 } 856 klassOop the_class_oop = java_lang_Class::as_klassOop(mirror); 857 instanceKlassHandle the_class = instanceKlassHandle(THREAD, the_class_oop); 858 symbolHandle the_class_sym = symbolHandle(THREAD, the_class->name()); 859 860 // RC_TRACE_WITH_THREAD macro has an embedded ResourceMark 861 RC_TRACE_WITH_THREAD(0x00000001, THREAD, 862 ("loading name=%s (avail_mem=" UINT64_FORMAT "K)", 863 the_class->external_name(), os::available_memory() >> 10)); 864 865 ClassFileStream st((u1*) _class_defs[i].class_bytes, 866 _class_defs[i].class_byte_count, (char *)"__VM_RedefineClasses__"); 867 868 // Parse the stream. 869 Handle the_class_loader(THREAD, the_class->class_loader()); 870 Handle protection_domain(THREAD, the_class->protection_domain()); 871 // Set redefined class handle in JvmtiThreadState class. 872 // This redefined class is sent to agent event handler for class file 873 // load hook event. 874 state->set_class_being_redefined(&the_class, _class_load_kind); 875 876 klassOop k = SystemDictionary::parse_stream(the_class_sym, 877 the_class_loader, 878 protection_domain, 879 &st, 880 THREAD); 881 // Clear class_being_redefined just to be sure. 882 state->clear_class_being_redefined(); 883 884 // TODO: if this is retransform, and nothing changed we can skip it 885 886 instanceKlassHandle scratch_class (THREAD, k); 887 888 if (HAS_PENDING_EXCEPTION) { 889 symbolOop ex_name = PENDING_EXCEPTION->klass()->klass_part()->name(); 890 // RC_TRACE_WITH_THREAD macro has an embedded ResourceMark 891 RC_TRACE_WITH_THREAD(0x00000002, THREAD, ("parse_stream exception: '%s'", 892 ex_name->as_C_string())); 893 CLEAR_PENDING_EXCEPTION; 894 895 if (ex_name == vmSymbols::java_lang_UnsupportedClassVersionError()) { 896 return JVMTI_ERROR_UNSUPPORTED_VERSION; 897 } else if (ex_name == vmSymbols::java_lang_ClassFormatError()) { 898 return JVMTI_ERROR_INVALID_CLASS_FORMAT; 899 } else if (ex_name == vmSymbols::java_lang_ClassCircularityError()) { 900 return JVMTI_ERROR_CIRCULAR_CLASS_DEFINITION; 901 } else if (ex_name == vmSymbols::java_lang_NoClassDefFoundError()) { 902 // The message will be "XXX (wrong name: YYY)" 903 return JVMTI_ERROR_NAMES_DONT_MATCH; 904 } else if (ex_name == vmSymbols::java_lang_OutOfMemoryError()) { 905 return JVMTI_ERROR_OUT_OF_MEMORY; 906 } else { // Just in case more exceptions can be thrown.. 907 return JVMTI_ERROR_FAILS_VERIFICATION; 908 } 909 } 910 911 // Ensure class is linked before redefine 912 if (!the_class->is_linked()) { 913 the_class->link_class(THREAD); 914 if (HAS_PENDING_EXCEPTION) { 915 symbolOop ex_name = PENDING_EXCEPTION->klass()->klass_part()->name(); 916 // RC_TRACE_WITH_THREAD macro has an embedded ResourceMark 917 RC_TRACE_WITH_THREAD(0x00000002, THREAD, ("link_class exception: '%s'", 918 ex_name->as_C_string())); 919 CLEAR_PENDING_EXCEPTION; 920 if (ex_name == vmSymbols::java_lang_OutOfMemoryError()) { 921 return JVMTI_ERROR_OUT_OF_MEMORY; 922 } else { 923 return JVMTI_ERROR_INTERNAL; 924 } 925 } 926 } 927 928 // Do the validity checks in compare_and_normalize_class_versions() 929 // before verifying the byte codes. By doing these checks first, we 930 // limit the number of functions that require redirection from 931 // the_class to scratch_class. In particular, we don't have to 932 // modify JNI GetSuperclass() and thus won't change its performance. 933 jvmtiError res = compare_and_normalize_class_versions(the_class, 934 scratch_class); 935 if (res != JVMTI_ERROR_NONE) { 936 return res; 937 } 938 939 // verify what the caller passed us 940 { 941 // The bug 6214132 caused the verification to fail. 942 // Information about the_class and scratch_class is temporarily 943 // recorded into jvmtiThreadState. This data is used to redirect 944 // the_class to scratch_class in the JVM_* functions called by the 945 // verifier. Please, refer to jvmtiThreadState.hpp for the detailed 946 // description. 947 RedefineVerifyMark rvm(&the_class, &scratch_class, state); 948 Verifier::verify( 949 scratch_class, Verifier::ThrowException, true, THREAD); 950 } 951 952 if (HAS_PENDING_EXCEPTION) { 953 symbolOop ex_name = PENDING_EXCEPTION->klass()->klass_part()->name(); 954 // RC_TRACE_WITH_THREAD macro has an embedded ResourceMark 955 RC_TRACE_WITH_THREAD(0x00000002, THREAD, 956 ("verify_byte_codes exception: '%s'", ex_name->as_C_string())); 957 CLEAR_PENDING_EXCEPTION; 958 if (ex_name == vmSymbols::java_lang_OutOfMemoryError()) { 959 return JVMTI_ERROR_OUT_OF_MEMORY; 960 } else { 961 // tell the caller the bytecodes are bad 962 return JVMTI_ERROR_FAILS_VERIFICATION; 963 } 964 } 965 966 res = merge_cp_and_rewrite(the_class, scratch_class, THREAD); 967 if (res != JVMTI_ERROR_NONE) { 968 return res; 969 } 970 971 if (VerifyMergedCPBytecodes) { 972 // verify what we have done during constant pool merging 973 { 974 RedefineVerifyMark rvm(&the_class, &scratch_class, state); 975 Verifier::verify(scratch_class, Verifier::ThrowException, true, THREAD); 976 } 977 978 if (HAS_PENDING_EXCEPTION) { 979 symbolOop ex_name = PENDING_EXCEPTION->klass()->klass_part()->name(); 980 // RC_TRACE_WITH_THREAD macro has an embedded ResourceMark 981 RC_TRACE_WITH_THREAD(0x00000002, THREAD, 982 ("verify_byte_codes post merge-CP exception: '%s'", 983 ex_name->as_C_string())); 984 CLEAR_PENDING_EXCEPTION; 985 if (ex_name == vmSymbols::java_lang_OutOfMemoryError()) { 986 return JVMTI_ERROR_OUT_OF_MEMORY; 987 } else { 988 // tell the caller that constant pool merging screwed up 989 return JVMTI_ERROR_INTERNAL; 990 } 991 } 992 } 993 994 Rewriter::rewrite(scratch_class, THREAD); 995 if (HAS_PENDING_EXCEPTION) { 996 symbolOop ex_name = PENDING_EXCEPTION->klass()->klass_part()->name(); 997 CLEAR_PENDING_EXCEPTION; 998 if (ex_name == vmSymbols::java_lang_OutOfMemoryError()) { 999 return JVMTI_ERROR_OUT_OF_MEMORY; 1000 } else { 1001 return JVMTI_ERROR_INTERNAL; 1002 } 1003 } 1004 1005 _scratch_classes[i] = scratch_class; 1006 1007 // RC_TRACE_WITH_THREAD macro has an embedded ResourceMark 1008 RC_TRACE_WITH_THREAD(0x00000001, THREAD, 1009 ("loaded name=%s (avail_mem=" UINT64_FORMAT "K)", 1010 the_class->external_name(), os::available_memory() >> 10)); 1011 } 1012 1013 return JVMTI_ERROR_NONE; 1014} 1015 1016 1017// Map old_index to new_index as needed. scratch_cp is only needed 1018// for RC_TRACE() calls. 1019void VM_RedefineClasses::map_index(constantPoolHandle scratch_cp, 1020 int old_index, int new_index) { 1021 if (find_new_index(old_index) != 0) { 1022 // old_index is already mapped 1023 return; 1024 } 1025 1026 if (old_index == new_index) { 1027 // no mapping is needed 1028 return; 1029 } 1030 1031 _index_map_p->at_put(old_index, new_index); 1032 _index_map_count++; 1033 1034 RC_TRACE(0x00040000, ("mapped tag %d at index %d to %d", 1035 scratch_cp->tag_at(old_index).value(), old_index, new_index)); 1036} // end map_index() 1037 1038 1039// Merge old_cp and scratch_cp and return the results of the merge via 1040// merge_cp_p. The number of entries in *merge_cp_p is returned via 1041// merge_cp_length_p. The entries in old_cp occupy the same locations 1042// in *merge_cp_p. Also creates a map of indices from entries in 1043// scratch_cp to the corresponding entry in *merge_cp_p. Index map 1044// entries are only created for entries in scratch_cp that occupy a 1045// different location in *merged_cp_p. 1046bool VM_RedefineClasses::merge_constant_pools(constantPoolHandle old_cp, 1047 constantPoolHandle scratch_cp, constantPoolHandle *merge_cp_p, 1048 int *merge_cp_length_p, TRAPS) { 1049 1050 if (merge_cp_p == NULL) { 1051 assert(false, "caller must provide scatch constantPool"); 1052 return false; // robustness 1053 } 1054 if (merge_cp_length_p == NULL) { 1055 assert(false, "caller must provide scatch CP length"); 1056 return false; // robustness 1057 } 1058 // Worst case we need old_cp->length() + scratch_cp()->length(), 1059 // but the caller might be smart so make sure we have at least 1060 // the minimum. 1061 if ((*merge_cp_p)->length() < old_cp->length()) { 1062 assert(false, "merge area too small"); 1063 return false; // robustness 1064 } 1065 1066 RC_TRACE_WITH_THREAD(0x00010000, THREAD, 1067 ("old_cp_len=%d, scratch_cp_len=%d", old_cp->length(), 1068 scratch_cp->length())); 1069 1070 { 1071 // Pass 0: 1072 // The old_cp is copied to *merge_cp_p; this means that any code 1073 // using old_cp does not have to change. This work looks like a 1074 // perfect fit for constantPoolOop::copy_cp_to(), but we need to 1075 // handle one special case: 1076 // - revert JVM_CONSTANT_Class to JVM_CONSTANT_UnresolvedClass 1077 // This will make verification happy. 1078 1079 int old_i; // index into old_cp 1080 1081 // index zero (0) is not used in constantPools 1082 for (old_i = 1; old_i < old_cp->length(); old_i++) { 1083 // leave debugging crumb 1084 jbyte old_tag = old_cp->tag_at(old_i).value(); 1085 switch (old_tag) { 1086 case JVM_CONSTANT_Class: 1087 // revert the copy to JVM_CONSTANT_UnresolvedClass 1088 (*merge_cp_p)->unresolved_klass_at_put(old_i, 1089 old_cp->klass_name_at(old_i)); 1090 break; 1091 1092 case JVM_CONSTANT_Double: 1093 case JVM_CONSTANT_Long: 1094 // just copy the entry to *merge_cp_p, but double and long take 1095 // two constant pool entries 1096 old_cp->copy_entry_to(old_i, *merge_cp_p, old_i, CHECK_0); 1097 old_i++; 1098 break; 1099 1100 default: 1101 // just copy the entry to *merge_cp_p 1102 old_cp->copy_entry_to(old_i, *merge_cp_p, old_i, CHECK_0); 1103 break; 1104 } 1105 } // end for each old_cp entry 1106 1107 // We don't need to sanity check that *merge_cp_length_p is within 1108 // *merge_cp_p bounds since we have the minimum on-entry check above. 1109 (*merge_cp_length_p) = old_i; 1110 } 1111 1112 // merge_cp_len should be the same as old_cp->length() at this point 1113 // so this trace message is really a "warm-and-breathing" message. 1114 RC_TRACE_WITH_THREAD(0x00020000, THREAD, 1115 ("after pass 0: merge_cp_len=%d", *merge_cp_length_p)); 1116 1117 int scratch_i; // index into scratch_cp 1118 { 1119 // Pass 1a: 1120 // Compare scratch_cp entries to the old_cp entries that we have 1121 // already copied to *merge_cp_p. In this pass, we are eliminating 1122 // exact duplicates (matching entry at same index) so we only 1123 // compare entries in the common indice range. 1124 int increment = 1; 1125 int pass1a_length = MIN2(old_cp->length(), scratch_cp->length()); 1126 for (scratch_i = 1; scratch_i < pass1a_length; scratch_i += increment) { 1127 switch (scratch_cp->tag_at(scratch_i).value()) { 1128 case JVM_CONSTANT_Double: 1129 case JVM_CONSTANT_Long: 1130 // double and long take two constant pool entries 1131 increment = 2; 1132 break; 1133 1134 default: 1135 increment = 1; 1136 break; 1137 } 1138 1139 bool match = scratch_cp->compare_entry_to(scratch_i, *merge_cp_p, 1140 scratch_i, CHECK_0); 1141 if (match) { 1142 // found a match at the same index so nothing more to do 1143 continue; 1144 } else if (is_unresolved_class_mismatch(scratch_cp, scratch_i, 1145 *merge_cp_p, scratch_i)) { 1146 // The mismatch in compare_entry_to() above is because of a 1147 // resolved versus unresolved class entry at the same index 1148 // with the same string value. Since Pass 0 reverted any 1149 // class entries to unresolved class entries in *merge_cp_p, 1150 // we go with the unresolved class entry. 1151 continue; 1152 } else if (is_unresolved_string_mismatch(scratch_cp, scratch_i, 1153 *merge_cp_p, scratch_i)) { 1154 // The mismatch in compare_entry_to() above is because of a 1155 // resolved versus unresolved string entry at the same index 1156 // with the same string value. We can live with whichever 1157 // happens to be at scratch_i in *merge_cp_p. 1158 continue; 1159 } 1160 1161 int found_i = scratch_cp->find_matching_entry(scratch_i, *merge_cp_p, 1162 CHECK_0); 1163 if (found_i != 0) { 1164 guarantee(found_i != scratch_i, 1165 "compare_entry_to() and find_matching_entry() do not agree"); 1166 1167 // Found a matching entry somewhere else in *merge_cp_p so 1168 // just need a mapping entry. 1169 map_index(scratch_cp, scratch_i, found_i); 1170 continue; 1171 } 1172 1173 // The find_matching_entry() call above could fail to find a match 1174 // due to a resolved versus unresolved class or string entry situation 1175 // like we solved above with the is_unresolved_*_mismatch() calls. 1176 // However, we would have to call is_unresolved_*_mismatch() over 1177 // all of *merge_cp_p (potentially) and that doesn't seem to be 1178 // worth the time. 1179 1180 // No match found so we have to append this entry and any unique 1181 // referenced entries to *merge_cp_p. 1182 append_entry(scratch_cp, scratch_i, merge_cp_p, merge_cp_length_p, 1183 CHECK_0); 1184 } 1185 } 1186 1187 RC_TRACE_WITH_THREAD(0x00020000, THREAD, 1188 ("after pass 1a: merge_cp_len=%d, scratch_i=%d, index_map_len=%d", 1189 *merge_cp_length_p, scratch_i, _index_map_count)); 1190 1191 if (scratch_i < scratch_cp->length()) { 1192 // Pass 1b: 1193 // old_cp is smaller than scratch_cp so there are entries in 1194 // scratch_cp that we have not yet processed. We take care of 1195 // those now. 1196 int increment = 1; 1197 for (; scratch_i < scratch_cp->length(); scratch_i += increment) { 1198 switch (scratch_cp->tag_at(scratch_i).value()) { 1199 case JVM_CONSTANT_Double: 1200 case JVM_CONSTANT_Long: 1201 // double and long take two constant pool entries 1202 increment = 2; 1203 break; 1204 1205 default: 1206 increment = 1; 1207 break; 1208 } 1209 1210 int found_i = 1211 scratch_cp->find_matching_entry(scratch_i, *merge_cp_p, CHECK_0); 1212 if (found_i != 0) { 1213 // Found a matching entry somewhere else in *merge_cp_p so 1214 // just need a mapping entry. 1215 map_index(scratch_cp, scratch_i, found_i); 1216 continue; 1217 } 1218 1219 // No match found so we have to append this entry and any unique 1220 // referenced entries to *merge_cp_p. 1221 append_entry(scratch_cp, scratch_i, merge_cp_p, merge_cp_length_p, 1222 CHECK_0); 1223 } 1224 1225 RC_TRACE_WITH_THREAD(0x00020000, THREAD, 1226 ("after pass 1b: merge_cp_len=%d, scratch_i=%d, index_map_len=%d", 1227 *merge_cp_length_p, scratch_i, _index_map_count)); 1228 } 1229 1230 return true; 1231} // end merge_constant_pools() 1232 1233 1234// Merge constant pools between the_class and scratch_class and 1235// potentially rewrite bytecodes in scratch_class to use the merged 1236// constant pool. 1237jvmtiError VM_RedefineClasses::merge_cp_and_rewrite( 1238 instanceKlassHandle the_class, instanceKlassHandle scratch_class, 1239 TRAPS) { 1240 // worst case merged constant pool length is old and new combined 1241 int merge_cp_length = the_class->constants()->length() 1242 + scratch_class->constants()->length(); 1243 1244 constantPoolHandle old_cp(THREAD, the_class->constants()); 1245 constantPoolHandle scratch_cp(THREAD, scratch_class->constants()); 1246 1247 // Constant pools are not easily reused so we allocate a new one 1248 // each time. 1249 // merge_cp is created unsafe for concurrent GC processing. It 1250 // should be marked safe before discarding it because, even if 1251 // garbage. If it crosses a card boundary, it may be scanned 1252 // in order to find the start of the first complete object on the card. 1253 constantPoolHandle merge_cp(THREAD, 1254 oopFactory::new_constantPool(merge_cp_length, 1255 methodOopDesc::IsUnsafeConc, 1256 THREAD)); 1257 int orig_length = old_cp->orig_length(); 1258 if (orig_length == 0) { 1259 // This old_cp is an actual original constant pool. We save 1260 // the original length in the merged constant pool so that 1261 // merge_constant_pools() can be more efficient. If a constant 1262 // pool has a non-zero orig_length() value, then that constant 1263 // pool was created by a merge operation in RedefineClasses. 1264 merge_cp->set_orig_length(old_cp->length()); 1265 } else { 1266 // This old_cp is a merged constant pool from a previous 1267 // RedefineClasses() calls so just copy the orig_length() 1268 // value. 1269 merge_cp->set_orig_length(old_cp->orig_length()); 1270 } 1271 1272 ResourceMark rm(THREAD); 1273 _index_map_count = 0; 1274 _index_map_p = new intArray(scratch_cp->length(), -1); 1275 1276 bool result = merge_constant_pools(old_cp, scratch_cp, &merge_cp, 1277 &merge_cp_length, THREAD); 1278 if (!result) { 1279 // The merge can fail due to memory allocation failure or due 1280 // to robustness checks. 1281 return JVMTI_ERROR_INTERNAL; 1282 } 1283 1284 RC_TRACE_WITH_THREAD(0x00010000, THREAD, 1285 ("merge_cp_len=%d, index_map_len=%d", merge_cp_length, _index_map_count)); 1286 1287 if (_index_map_count == 0) { 1288 // there is nothing to map between the new and merged constant pools 1289 1290 if (old_cp->length() == scratch_cp->length()) { 1291 // The old and new constant pools are the same length and the 1292 // index map is empty. This means that the three constant pools 1293 // are equivalent (but not the same). Unfortunately, the new 1294 // constant pool has not gone through link resolution nor have 1295 // the new class bytecodes gone through constant pool cache 1296 // rewriting so we can't use the old constant pool with the new 1297 // class. 1298 1299 merge_cp()->set_is_conc_safe(true); 1300 merge_cp = constantPoolHandle(); // toss the merged constant pool 1301 } else if (old_cp->length() < scratch_cp->length()) { 1302 // The old constant pool has fewer entries than the new constant 1303 // pool and the index map is empty. This means the new constant 1304 // pool is a superset of the old constant pool. However, the old 1305 // class bytecodes have already gone through constant pool cache 1306 // rewriting so we can't use the new constant pool with the old 1307 // class. 1308 1309 merge_cp()->set_is_conc_safe(true); 1310 merge_cp = constantPoolHandle(); // toss the merged constant pool 1311 } else { 1312 // The old constant pool has more entries than the new constant 1313 // pool and the index map is empty. This means that both the old 1314 // and merged constant pools are supersets of the new constant 1315 // pool. 1316 1317 // Replace the new constant pool with a shrunken copy of the 1318 // merged constant pool; the previous new constant pool will 1319 // get GCed. 1320 set_new_constant_pool(scratch_class, merge_cp, merge_cp_length, true, 1321 THREAD); 1322 // drop local ref to the merged constant pool 1323 merge_cp()->set_is_conc_safe(true); 1324 merge_cp = constantPoolHandle(); 1325 } 1326 } else { 1327 if (RC_TRACE_ENABLED(0x00040000)) { 1328 // don't want to loop unless we are tracing 1329 int count = 0; 1330 for (int i = 1; i < _index_map_p->length(); i++) { 1331 int value = _index_map_p->at(i); 1332 1333 if (value != -1) { 1334 RC_TRACE_WITH_THREAD(0x00040000, THREAD, 1335 ("index_map[%d]: old=%d new=%d", count, i, value)); 1336 count++; 1337 } 1338 } 1339 } 1340 1341 // We have entries mapped between the new and merged constant pools 1342 // so we have to rewrite some constant pool references. 1343 if (!rewrite_cp_refs(scratch_class, THREAD)) { 1344 return JVMTI_ERROR_INTERNAL; 1345 } 1346 1347 // Replace the new constant pool with a shrunken copy of the 1348 // merged constant pool so now the rewritten bytecodes have 1349 // valid references; the previous new constant pool will get 1350 // GCed. 1351 set_new_constant_pool(scratch_class, merge_cp, merge_cp_length, true, 1352 THREAD); 1353 merge_cp()->set_is_conc_safe(true); 1354 } 1355 assert(old_cp()->is_conc_safe(), "Just checking"); 1356 assert(scratch_cp()->is_conc_safe(), "Just checking"); 1357 1358 return JVMTI_ERROR_NONE; 1359} // end merge_cp_and_rewrite() 1360 1361 1362// Rewrite constant pool references in klass scratch_class. 1363bool VM_RedefineClasses::rewrite_cp_refs(instanceKlassHandle scratch_class, 1364 TRAPS) { 1365 1366 // rewrite constant pool references in the methods: 1367 if (!rewrite_cp_refs_in_methods(scratch_class, THREAD)) { 1368 // propagate failure back to caller 1369 return false; 1370 } 1371 1372 // rewrite constant pool references in the class_annotations: 1373 if (!rewrite_cp_refs_in_class_annotations(scratch_class, THREAD)) { 1374 // propagate failure back to caller 1375 return false; 1376 } 1377 1378 // rewrite constant pool references in the fields_annotations: 1379 if (!rewrite_cp_refs_in_fields_annotations(scratch_class, THREAD)) { 1380 // propagate failure back to caller 1381 return false; 1382 } 1383 1384 // rewrite constant pool references in the methods_annotations: 1385 if (!rewrite_cp_refs_in_methods_annotations(scratch_class, THREAD)) { 1386 // propagate failure back to caller 1387 return false; 1388 } 1389 1390 // rewrite constant pool references in the methods_parameter_annotations: 1391 if (!rewrite_cp_refs_in_methods_parameter_annotations(scratch_class, 1392 THREAD)) { 1393 // propagate failure back to caller 1394 return false; 1395 } 1396 1397 // rewrite constant pool references in the methods_default_annotations: 1398 if (!rewrite_cp_refs_in_methods_default_annotations(scratch_class, 1399 THREAD)) { 1400 // propagate failure back to caller 1401 return false; 1402 } 1403 1404 return true; 1405} // end rewrite_cp_refs() 1406 1407 1408// Rewrite constant pool references in the methods. 1409bool VM_RedefineClasses::rewrite_cp_refs_in_methods( 1410 instanceKlassHandle scratch_class, TRAPS) { 1411 1412 objArrayHandle methods(THREAD, scratch_class->methods()); 1413 1414 if (methods.is_null() || methods->length() == 0) { 1415 // no methods so nothing to do 1416 return true; 1417 } 1418 1419 // rewrite constant pool references in the methods: 1420 for (int i = methods->length() - 1; i >= 0; i--) { 1421 methodHandle method(THREAD, (methodOop)methods->obj_at(i)); 1422 methodHandle new_method; 1423 rewrite_cp_refs_in_method(method, &new_method, CHECK_false); 1424 if (!new_method.is_null()) { 1425 // the method has been replaced so save the new method version 1426 methods->obj_at_put(i, new_method()); 1427 } 1428 } 1429 1430 return true; 1431} 1432 1433 1434// Rewrite constant pool references in the specific method. This code 1435// was adapted from Rewriter::rewrite_method(). 1436void VM_RedefineClasses::rewrite_cp_refs_in_method(methodHandle method, 1437 methodHandle *new_method_p, TRAPS) { 1438 1439 *new_method_p = methodHandle(); // default is no new method 1440 1441 // We cache a pointer to the bytecodes here in code_base. If GC 1442 // moves the methodOop, then the bytecodes will also move which 1443 // will likely cause a crash. We create a No_Safepoint_Verifier 1444 // object to detect whether we pass a possible safepoint in this 1445 // code block. 1446 No_Safepoint_Verifier nsv; 1447 1448 // Bytecodes and their length 1449 address code_base = method->code_base(); 1450 int code_length = method->code_size(); 1451 1452 int bc_length; 1453 for (int bci = 0; bci < code_length; bci += bc_length) { 1454 address bcp = code_base + bci; 1455 Bytecodes::Code c = (Bytecodes::Code)(*bcp); 1456 1457 bc_length = Bytecodes::length_for(c); 1458 if (bc_length == 0) { 1459 // More complicated bytecodes report a length of zero so 1460 // we have to try again a slightly different way. 1461 bc_length = Bytecodes::length_at(bcp); 1462 } 1463 1464 assert(bc_length != 0, "impossible bytecode length"); 1465 1466 switch (c) { 1467 case Bytecodes::_ldc: 1468 { 1469 int cp_index = *(bcp + 1); 1470 int new_index = find_new_index(cp_index); 1471 1472 if (StressLdcRewrite && new_index == 0) { 1473 // If we are stressing ldc -> ldc_w rewriting, then we 1474 // always need a new_index value. 1475 new_index = cp_index; 1476 } 1477 if (new_index != 0) { 1478 // the original index is mapped so we have more work to do 1479 if (!StressLdcRewrite && new_index <= max_jubyte) { 1480 // The new value can still use ldc instead of ldc_w 1481 // unless we are trying to stress ldc -> ldc_w rewriting 1482 RC_TRACE_WITH_THREAD(0x00080000, THREAD, 1483 ("%s@" INTPTR_FORMAT " old=%d, new=%d", Bytecodes::name(c), 1484 bcp, cp_index, new_index)); 1485 *(bcp + 1) = new_index; 1486 } else { 1487 RC_TRACE_WITH_THREAD(0x00080000, THREAD, 1488 ("%s->ldc_w@" INTPTR_FORMAT " old=%d, new=%d", 1489 Bytecodes::name(c), bcp, cp_index, new_index)); 1490 // the new value needs ldc_w instead of ldc 1491 u_char inst_buffer[4]; // max instruction size is 4 bytes 1492 bcp = (address)inst_buffer; 1493 // construct new instruction sequence 1494 *bcp = Bytecodes::_ldc_w; 1495 bcp++; 1496 // Rewriter::rewrite_method() does not rewrite ldc -> ldc_w. 1497 // See comment below for difference between put_Java_u2() 1498 // and put_native_u2(). 1499 Bytes::put_Java_u2(bcp, new_index); 1500 1501 Relocator rc(method, NULL /* no RelocatorListener needed */); 1502 methodHandle m; 1503 { 1504 Pause_No_Safepoint_Verifier pnsv(&nsv); 1505 1506 // ldc is 2 bytes and ldc_w is 3 bytes 1507 m = rc.insert_space_at(bci, 3, inst_buffer, THREAD); 1508 if (m.is_null() || HAS_PENDING_EXCEPTION) { 1509 guarantee(false, "insert_space_at() failed"); 1510 } 1511 } 1512 1513 // return the new method so that the caller can update 1514 // the containing class 1515 *new_method_p = method = m; 1516 // switch our bytecode processing loop from the old method 1517 // to the new method 1518 code_base = method->code_base(); 1519 code_length = method->code_size(); 1520 bcp = code_base + bci; 1521 c = (Bytecodes::Code)(*bcp); 1522 bc_length = Bytecodes::length_for(c); 1523 assert(bc_length != 0, "sanity check"); 1524 } // end we need ldc_w instead of ldc 1525 } // end if there is a mapped index 1526 } break; 1527 1528 // these bytecodes have a two-byte constant pool index 1529 case Bytecodes::_anewarray : // fall through 1530 case Bytecodes::_checkcast : // fall through 1531 case Bytecodes::_getfield : // fall through 1532 case Bytecodes::_getstatic : // fall through 1533 case Bytecodes::_instanceof : // fall through 1534 case Bytecodes::_invokeinterface: // fall through 1535 case Bytecodes::_invokespecial : // fall through 1536 case Bytecodes::_invokestatic : // fall through 1537 case Bytecodes::_invokevirtual : // fall through 1538 case Bytecodes::_ldc_w : // fall through 1539 case Bytecodes::_ldc2_w : // fall through 1540 case Bytecodes::_multianewarray : // fall through 1541 case Bytecodes::_new : // fall through 1542 case Bytecodes::_putfield : // fall through 1543 case Bytecodes::_putstatic : 1544 { 1545 address p = bcp + 1; 1546 int cp_index = Bytes::get_Java_u2(p); 1547 int new_index = find_new_index(cp_index); 1548 if (new_index != 0) { 1549 // the original index is mapped so update w/ new value 1550 RC_TRACE_WITH_THREAD(0x00080000, THREAD, 1551 ("%s@" INTPTR_FORMAT " old=%d, new=%d", Bytecodes::name(c), 1552 bcp, cp_index, new_index)); 1553 // Rewriter::rewrite_method() uses put_native_u2() in this 1554 // situation because it is reusing the constant pool index 1555 // location for a native index into the constantPoolCache. 1556 // Since we are updating the constant pool index prior to 1557 // verification and constantPoolCache initialization, we 1558 // need to keep the new index in Java byte order. 1559 Bytes::put_Java_u2(p, new_index); 1560 } 1561 } break; 1562 } 1563 } // end for each bytecode 1564} // end rewrite_cp_refs_in_method() 1565 1566 1567// Rewrite constant pool references in the class_annotations field. 1568bool VM_RedefineClasses::rewrite_cp_refs_in_class_annotations( 1569 instanceKlassHandle scratch_class, TRAPS) { 1570 1571 typeArrayHandle class_annotations(THREAD, 1572 scratch_class->class_annotations()); 1573 if (class_annotations.is_null() || class_annotations->length() == 0) { 1574 // no class_annotations so nothing to do 1575 return true; 1576 } 1577 1578 RC_TRACE_WITH_THREAD(0x02000000, THREAD, 1579 ("class_annotations length=%d", class_annotations->length())); 1580 1581 int byte_i = 0; // byte index into class_annotations 1582 return rewrite_cp_refs_in_annotations_typeArray(class_annotations, byte_i, 1583 THREAD); 1584} 1585 1586 1587// Rewrite constant pool references in an annotations typeArray. This 1588// "structure" is adapted from the RuntimeVisibleAnnotations_attribute 1589// that is described in section 4.8.15 of the 2nd-edition of the VM spec: 1590// 1591// annotations_typeArray { 1592// u2 num_annotations; 1593// annotation annotations[num_annotations]; 1594// } 1595// 1596bool VM_RedefineClasses::rewrite_cp_refs_in_annotations_typeArray( 1597 typeArrayHandle annotations_typeArray, int &byte_i_ref, TRAPS) { 1598 1599 if ((byte_i_ref + 2) > annotations_typeArray->length()) { 1600 // not enough room for num_annotations field 1601 RC_TRACE_WITH_THREAD(0x02000000, THREAD, 1602 ("length() is too small for num_annotations field")); 1603 return false; 1604 } 1605 1606 u2 num_annotations = Bytes::get_Java_u2((address) 1607 annotations_typeArray->byte_at_addr(byte_i_ref)); 1608 byte_i_ref += 2; 1609 1610 RC_TRACE_WITH_THREAD(0x02000000, THREAD, 1611 ("num_annotations=%d", num_annotations)); 1612 1613 int calc_num_annotations = 0; 1614 for (; calc_num_annotations < num_annotations; calc_num_annotations++) { 1615 if (!rewrite_cp_refs_in_annotation_struct(annotations_typeArray, 1616 byte_i_ref, THREAD)) { 1617 RC_TRACE_WITH_THREAD(0x02000000, THREAD, 1618 ("bad annotation_struct at %d", calc_num_annotations)); 1619 // propagate failure back to caller 1620 return false; 1621 } 1622 } 1623 assert(num_annotations == calc_num_annotations, "sanity check"); 1624 1625 return true; 1626} // end rewrite_cp_refs_in_annotations_typeArray() 1627 1628 1629// Rewrite constant pool references in the annotation struct portion of 1630// an annotations_typeArray. This "structure" is from section 4.8.15 of 1631// the 2nd-edition of the VM spec: 1632// 1633// struct annotation { 1634// u2 type_index; 1635// u2 num_element_value_pairs; 1636// { 1637// u2 element_name_index; 1638// element_value value; 1639// } element_value_pairs[num_element_value_pairs]; 1640// } 1641// 1642bool VM_RedefineClasses::rewrite_cp_refs_in_annotation_struct( 1643 typeArrayHandle annotations_typeArray, int &byte_i_ref, TRAPS) { 1644 if ((byte_i_ref + 2 + 2) > annotations_typeArray->length()) { 1645 // not enough room for smallest annotation_struct 1646 RC_TRACE_WITH_THREAD(0x02000000, THREAD, 1647 ("length() is too small for annotation_struct")); 1648 return false; 1649 } 1650 1651 u2 type_index = rewrite_cp_ref_in_annotation_data(annotations_typeArray, 1652 byte_i_ref, "mapped old type_index=%d", THREAD); 1653 1654 u2 num_element_value_pairs = Bytes::get_Java_u2((address) 1655 annotations_typeArray->byte_at_addr( 1656 byte_i_ref)); 1657 byte_i_ref += 2; 1658 1659 RC_TRACE_WITH_THREAD(0x02000000, THREAD, 1660 ("type_index=%d num_element_value_pairs=%d", type_index, 1661 num_element_value_pairs)); 1662 1663 int calc_num_element_value_pairs = 0; 1664 for (; calc_num_element_value_pairs < num_element_value_pairs; 1665 calc_num_element_value_pairs++) { 1666 if ((byte_i_ref + 2) > annotations_typeArray->length()) { 1667 // not enough room for another element_name_index, let alone 1668 // the rest of another component 1669 RC_TRACE_WITH_THREAD(0x02000000, THREAD, 1670 ("length() is too small for element_name_index")); 1671 return false; 1672 } 1673 1674 u2 element_name_index = rewrite_cp_ref_in_annotation_data( 1675 annotations_typeArray, byte_i_ref, 1676 "mapped old element_name_index=%d", THREAD); 1677 1678 RC_TRACE_WITH_THREAD(0x02000000, THREAD, 1679 ("element_name_index=%d", element_name_index)); 1680 1681 if (!rewrite_cp_refs_in_element_value(annotations_typeArray, 1682 byte_i_ref, THREAD)) { 1683 RC_TRACE_WITH_THREAD(0x02000000, THREAD, 1684 ("bad element_value at %d", calc_num_element_value_pairs)); 1685 // propagate failure back to caller 1686 return false; 1687 } 1688 } // end for each component 1689 assert(num_element_value_pairs == calc_num_element_value_pairs, 1690 "sanity check"); 1691 1692 return true; 1693} // end rewrite_cp_refs_in_annotation_struct() 1694 1695 1696// Rewrite a constant pool reference at the current position in 1697// annotations_typeArray if needed. Returns the original constant 1698// pool reference if a rewrite was not needed or the new constant 1699// pool reference if a rewrite was needed. 1700u2 VM_RedefineClasses::rewrite_cp_ref_in_annotation_data( 1701 typeArrayHandle annotations_typeArray, int &byte_i_ref, 1702 const char * trace_mesg, TRAPS) { 1703 1704 address cp_index_addr = (address) 1705 annotations_typeArray->byte_at_addr(byte_i_ref); 1706 u2 old_cp_index = Bytes::get_Java_u2(cp_index_addr); 1707 u2 new_cp_index = find_new_index(old_cp_index); 1708 if (new_cp_index != 0) { 1709 RC_TRACE_WITH_THREAD(0x02000000, THREAD, (trace_mesg, old_cp_index)); 1710 Bytes::put_Java_u2(cp_index_addr, new_cp_index); 1711 old_cp_index = new_cp_index; 1712 } 1713 byte_i_ref += 2; 1714 return old_cp_index; 1715} 1716 1717 1718// Rewrite constant pool references in the element_value portion of an 1719// annotations_typeArray. This "structure" is from section 4.8.15.1 of 1720// the 2nd-edition of the VM spec: 1721// 1722// struct element_value { 1723// u1 tag; 1724// union { 1725// u2 const_value_index; 1726// { 1727// u2 type_name_index; 1728// u2 const_name_index; 1729// } enum_const_value; 1730// u2 class_info_index; 1731// annotation annotation_value; 1732// struct { 1733// u2 num_values; 1734// element_value values[num_values]; 1735// } array_value; 1736// } value; 1737// } 1738// 1739bool VM_RedefineClasses::rewrite_cp_refs_in_element_value( 1740 typeArrayHandle annotations_typeArray, int &byte_i_ref, TRAPS) { 1741 1742 if ((byte_i_ref + 1) > annotations_typeArray->length()) { 1743 // not enough room for a tag let alone the rest of an element_value 1744 RC_TRACE_WITH_THREAD(0x02000000, THREAD, 1745 ("length() is too small for a tag")); 1746 return false; 1747 } 1748 1749 u1 tag = annotations_typeArray->byte_at(byte_i_ref); 1750 byte_i_ref++; 1751 RC_TRACE_WITH_THREAD(0x02000000, THREAD, ("tag='%c'", tag)); 1752 1753 switch (tag) { 1754 // These BaseType tag values are from Table 4.2 in VM spec: 1755 case 'B': // byte 1756 case 'C': // char 1757 case 'D': // double 1758 case 'F': // float 1759 case 'I': // int 1760 case 'J': // long 1761 case 'S': // short 1762 case 'Z': // boolean 1763 1764 // The remaining tag values are from Table 4.8 in the 2nd-edition of 1765 // the VM spec: 1766 case 's': 1767 { 1768 // For the above tag values (including the BaseType values), 1769 // value.const_value_index is right union field. 1770 1771 if ((byte_i_ref + 2) > annotations_typeArray->length()) { 1772 // not enough room for a const_value_index 1773 RC_TRACE_WITH_THREAD(0x02000000, THREAD, 1774 ("length() is too small for a const_value_index")); 1775 return false; 1776 } 1777 1778 u2 const_value_index = rewrite_cp_ref_in_annotation_data( 1779 annotations_typeArray, byte_i_ref, 1780 "mapped old const_value_index=%d", THREAD); 1781 1782 RC_TRACE_WITH_THREAD(0x02000000, THREAD, 1783 ("const_value_index=%d", const_value_index)); 1784 } break; 1785 1786 case 'e': 1787 { 1788 // for the above tag value, value.enum_const_value is right union field 1789 1790 if ((byte_i_ref + 4) > annotations_typeArray->length()) { 1791 // not enough room for a enum_const_value 1792 RC_TRACE_WITH_THREAD(0x02000000, THREAD, 1793 ("length() is too small for a enum_const_value")); 1794 return false; 1795 } 1796 1797 u2 type_name_index = rewrite_cp_ref_in_annotation_data( 1798 annotations_typeArray, byte_i_ref, 1799 "mapped old type_name_index=%d", THREAD); 1800 1801 u2 const_name_index = rewrite_cp_ref_in_annotation_data( 1802 annotations_typeArray, byte_i_ref, 1803 "mapped old const_name_index=%d", THREAD); 1804 1805 RC_TRACE_WITH_THREAD(0x02000000, THREAD, 1806 ("type_name_index=%d const_name_index=%d", type_name_index, 1807 const_name_index)); 1808 } break; 1809 1810 case 'c': 1811 { 1812 // for the above tag value, value.class_info_index is right union field 1813 1814 if ((byte_i_ref + 2) > annotations_typeArray->length()) { 1815 // not enough room for a class_info_index 1816 RC_TRACE_WITH_THREAD(0x02000000, THREAD, 1817 ("length() is too small for a class_info_index")); 1818 return false; 1819 } 1820 1821 u2 class_info_index = rewrite_cp_ref_in_annotation_data( 1822 annotations_typeArray, byte_i_ref, 1823 "mapped old class_info_index=%d", THREAD); 1824 1825 RC_TRACE_WITH_THREAD(0x02000000, THREAD, 1826 ("class_info_index=%d", class_info_index)); 1827 } break; 1828 1829 case '@': 1830 // For the above tag value, value.attr_value is the right union 1831 // field. This is a nested annotation. 1832 if (!rewrite_cp_refs_in_annotation_struct(annotations_typeArray, 1833 byte_i_ref, THREAD)) { 1834 // propagate failure back to caller 1835 return false; 1836 } 1837 break; 1838 1839 case '[': 1840 { 1841 if ((byte_i_ref + 2) > annotations_typeArray->length()) { 1842 // not enough room for a num_values field 1843 RC_TRACE_WITH_THREAD(0x02000000, THREAD, 1844 ("length() is too small for a num_values field")); 1845 return false; 1846 } 1847 1848 // For the above tag value, value.array_value is the right union 1849 // field. This is an array of nested element_value. 1850 u2 num_values = Bytes::get_Java_u2((address) 1851 annotations_typeArray->byte_at_addr(byte_i_ref)); 1852 byte_i_ref += 2; 1853 RC_TRACE_WITH_THREAD(0x02000000, THREAD, ("num_values=%d", num_values)); 1854 1855 int calc_num_values = 0; 1856 for (; calc_num_values < num_values; calc_num_values++) { 1857 if (!rewrite_cp_refs_in_element_value( 1858 annotations_typeArray, byte_i_ref, THREAD)) { 1859 RC_TRACE_WITH_THREAD(0x02000000, THREAD, 1860 ("bad nested element_value at %d", calc_num_values)); 1861 // propagate failure back to caller 1862 return false; 1863 } 1864 } 1865 assert(num_values == calc_num_values, "sanity check"); 1866 } break; 1867 1868 default: 1869 RC_TRACE_WITH_THREAD(0x02000000, THREAD, ("bad tag=0x%x", tag)); 1870 return false; 1871 } // end decode tag field 1872 1873 return true; 1874} // end rewrite_cp_refs_in_element_value() 1875 1876 1877// Rewrite constant pool references in a fields_annotations field. 1878bool VM_RedefineClasses::rewrite_cp_refs_in_fields_annotations( 1879 instanceKlassHandle scratch_class, TRAPS) { 1880 1881 objArrayHandle fields_annotations(THREAD, 1882 scratch_class->fields_annotations()); 1883 1884 if (fields_annotations.is_null() || fields_annotations->length() == 0) { 1885 // no fields_annotations so nothing to do 1886 return true; 1887 } 1888 1889 RC_TRACE_WITH_THREAD(0x02000000, THREAD, 1890 ("fields_annotations length=%d", fields_annotations->length())); 1891 1892 for (int i = 0; i < fields_annotations->length(); i++) { 1893 typeArrayHandle field_annotations(THREAD, 1894 (typeArrayOop)fields_annotations->obj_at(i)); 1895 if (field_annotations.is_null() || field_annotations->length() == 0) { 1896 // this field does not have any annotations so skip it 1897 continue; 1898 } 1899 1900 int byte_i = 0; // byte index into field_annotations 1901 if (!rewrite_cp_refs_in_annotations_typeArray(field_annotations, byte_i, 1902 THREAD)) { 1903 RC_TRACE_WITH_THREAD(0x02000000, THREAD, 1904 ("bad field_annotations at %d", i)); 1905 // propagate failure back to caller 1906 return false; 1907 } 1908 } 1909 1910 return true; 1911} // end rewrite_cp_refs_in_fields_annotations() 1912 1913 1914// Rewrite constant pool references in a methods_annotations field. 1915bool VM_RedefineClasses::rewrite_cp_refs_in_methods_annotations( 1916 instanceKlassHandle scratch_class, TRAPS) { 1917 1918 objArrayHandle methods_annotations(THREAD, 1919 scratch_class->methods_annotations()); 1920 1921 if (methods_annotations.is_null() || methods_annotations->length() == 0) { 1922 // no methods_annotations so nothing to do 1923 return true; 1924 } 1925 1926 RC_TRACE_WITH_THREAD(0x02000000, THREAD, 1927 ("methods_annotations length=%d", methods_annotations->length())); 1928 1929 for (int i = 0; i < methods_annotations->length(); i++) { 1930 typeArrayHandle method_annotations(THREAD, 1931 (typeArrayOop)methods_annotations->obj_at(i)); 1932 if (method_annotations.is_null() || method_annotations->length() == 0) { 1933 // this method does not have any annotations so skip it 1934 continue; 1935 } 1936 1937 int byte_i = 0; // byte index into method_annotations 1938 if (!rewrite_cp_refs_in_annotations_typeArray(method_annotations, byte_i, 1939 THREAD)) { 1940 RC_TRACE_WITH_THREAD(0x02000000, THREAD, 1941 ("bad method_annotations at %d", i)); 1942 // propagate failure back to caller 1943 return false; 1944 } 1945 } 1946 1947 return true; 1948} // end rewrite_cp_refs_in_methods_annotations() 1949 1950 1951// Rewrite constant pool references in a methods_parameter_annotations 1952// field. This "structure" is adapted from the 1953// RuntimeVisibleParameterAnnotations_attribute described in section 1954// 4.8.17 of the 2nd-edition of the VM spec: 1955// 1956// methods_parameter_annotations_typeArray { 1957// u1 num_parameters; 1958// { 1959// u2 num_annotations; 1960// annotation annotations[num_annotations]; 1961// } parameter_annotations[num_parameters]; 1962// } 1963// 1964bool VM_RedefineClasses::rewrite_cp_refs_in_methods_parameter_annotations( 1965 instanceKlassHandle scratch_class, TRAPS) { 1966 1967 objArrayHandle methods_parameter_annotations(THREAD, 1968 scratch_class->methods_parameter_annotations()); 1969 1970 if (methods_parameter_annotations.is_null() 1971 || methods_parameter_annotations->length() == 0) { 1972 // no methods_parameter_annotations so nothing to do 1973 return true; 1974 } 1975 1976 RC_TRACE_WITH_THREAD(0x02000000, THREAD, 1977 ("methods_parameter_annotations length=%d", 1978 methods_parameter_annotations->length())); 1979 1980 for (int i = 0; i < methods_parameter_annotations->length(); i++) { 1981 typeArrayHandle method_parameter_annotations(THREAD, 1982 (typeArrayOop)methods_parameter_annotations->obj_at(i)); 1983 if (method_parameter_annotations.is_null() 1984 || method_parameter_annotations->length() == 0) { 1985 // this method does not have any parameter annotations so skip it 1986 continue; 1987 } 1988 1989 if (method_parameter_annotations->length() < 1) { 1990 // not enough room for a num_parameters field 1991 RC_TRACE_WITH_THREAD(0x02000000, THREAD, 1992 ("length() is too small for a num_parameters field at %d", i)); 1993 return false; 1994 } 1995 1996 int byte_i = 0; // byte index into method_parameter_annotations 1997 1998 u1 num_parameters = method_parameter_annotations->byte_at(byte_i); 1999 byte_i++; 2000 2001 RC_TRACE_WITH_THREAD(0x02000000, THREAD, 2002 ("num_parameters=%d", num_parameters)); 2003 2004 int calc_num_parameters = 0; 2005 for (; calc_num_parameters < num_parameters; calc_num_parameters++) { 2006 if (!rewrite_cp_refs_in_annotations_typeArray( 2007 method_parameter_annotations, byte_i, THREAD)) { 2008 RC_TRACE_WITH_THREAD(0x02000000, THREAD, 2009 ("bad method_parameter_annotations at %d", calc_num_parameters)); 2010 // propagate failure back to caller 2011 return false; 2012 } 2013 } 2014 assert(num_parameters == calc_num_parameters, "sanity check"); 2015 } 2016 2017 return true; 2018} // end rewrite_cp_refs_in_methods_parameter_annotations() 2019 2020 2021// Rewrite constant pool references in a methods_default_annotations 2022// field. This "structure" is adapted from the AnnotationDefault_attribute 2023// that is described in section 4.8.19 of the 2nd-edition of the VM spec: 2024// 2025// methods_default_annotations_typeArray { 2026// element_value default_value; 2027// } 2028// 2029bool VM_RedefineClasses::rewrite_cp_refs_in_methods_default_annotations( 2030 instanceKlassHandle scratch_class, TRAPS) { 2031 2032 objArrayHandle methods_default_annotations(THREAD, 2033 scratch_class->methods_default_annotations()); 2034 2035 if (methods_default_annotations.is_null() 2036 || methods_default_annotations->length() == 0) { 2037 // no methods_default_annotations so nothing to do 2038 return true; 2039 } 2040 2041 RC_TRACE_WITH_THREAD(0x02000000, THREAD, 2042 ("methods_default_annotations length=%d", 2043 methods_default_annotations->length())); 2044 2045 for (int i = 0; i < methods_default_annotations->length(); i++) { 2046 typeArrayHandle method_default_annotations(THREAD, 2047 (typeArrayOop)methods_default_annotations->obj_at(i)); 2048 if (method_default_annotations.is_null() 2049 || method_default_annotations->length() == 0) { 2050 // this method does not have any default annotations so skip it 2051 continue; 2052 } 2053 2054 int byte_i = 0; // byte index into method_default_annotations 2055 2056 if (!rewrite_cp_refs_in_element_value( 2057 method_default_annotations, byte_i, THREAD)) { 2058 RC_TRACE_WITH_THREAD(0x02000000, THREAD, 2059 ("bad default element_value at %d", i)); 2060 // propagate failure back to caller 2061 return false; 2062 } 2063 } 2064 2065 return true; 2066} // end rewrite_cp_refs_in_methods_default_annotations() 2067 2068 2069// Rewrite constant pool references in the method's stackmap table. 2070// These "structures" are adapted from the StackMapTable_attribute that 2071// is described in section 4.8.4 of the 6.0 version of the VM spec 2072// (dated 2005.10.26): 2073// file:///net/quincunx.sfbay/export/gbracha/ClassFile-Java6.pdf 2074// 2075// stack_map { 2076// u2 number_of_entries; 2077// stack_map_frame entries[number_of_entries]; 2078// } 2079// 2080void VM_RedefineClasses::rewrite_cp_refs_in_stack_map_table( 2081 methodHandle method, TRAPS) { 2082 2083 if (!method->has_stackmap_table()) { 2084 return; 2085 } 2086 2087 typeArrayOop stackmap_data = method->stackmap_data(); 2088 address stackmap_p = (address)stackmap_data->byte_at_addr(0); 2089 address stackmap_end = stackmap_p + stackmap_data->length(); 2090 2091 assert(stackmap_p + 2 <= stackmap_end, "no room for number_of_entries"); 2092 u2 number_of_entries = Bytes::get_Java_u2(stackmap_p); 2093 stackmap_p += 2; 2094 2095 RC_TRACE_WITH_THREAD(0x04000000, THREAD, 2096 ("number_of_entries=%u", number_of_entries)); 2097 2098 // walk through each stack_map_frame 2099 u2 calc_number_of_entries = 0; 2100 for (; calc_number_of_entries < number_of_entries; calc_number_of_entries++) { 2101 // The stack_map_frame structure is a u1 frame_type followed by 2102 // 0 or more bytes of data: 2103 // 2104 // union stack_map_frame { 2105 // same_frame; 2106 // same_locals_1_stack_item_frame; 2107 // same_locals_1_stack_item_frame_extended; 2108 // chop_frame; 2109 // same_frame_extended; 2110 // append_frame; 2111 // full_frame; 2112 // } 2113 2114 assert(stackmap_p + 1 <= stackmap_end, "no room for frame_type"); 2115 // The Linux compiler does not like frame_type to be u1 or u2. It 2116 // issues the following warning for the first if-statement below: 2117 // 2118 // "warning: comparison is always true due to limited range of data type" 2119 // 2120 u4 frame_type = *stackmap_p; 2121 stackmap_p++; 2122 2123 // same_frame { 2124 // u1 frame_type = SAME; /* 0-63 */ 2125 // } 2126 if (frame_type >= 0 && frame_type <= 63) { 2127 // nothing more to do for same_frame 2128 } 2129 2130 // same_locals_1_stack_item_frame { 2131 // u1 frame_type = SAME_LOCALS_1_STACK_ITEM; /* 64-127 */ 2132 // verification_type_info stack[1]; 2133 // } 2134 else if (frame_type >= 64 && frame_type <= 127) { 2135 rewrite_cp_refs_in_verification_type_info(stackmap_p, stackmap_end, 2136 calc_number_of_entries, frame_type, THREAD); 2137 } 2138 2139 // reserved for future use 2140 else if (frame_type >= 128 && frame_type <= 246) { 2141 // nothing more to do for reserved frame_types 2142 } 2143 2144 // same_locals_1_stack_item_frame_extended { 2145 // u1 frame_type = SAME_LOCALS_1_STACK_ITEM_EXTENDED; /* 247 */ 2146 // u2 offset_delta; 2147 // verification_type_info stack[1]; 2148 // } 2149 else if (frame_type == 247) { 2150 stackmap_p += 2; 2151 rewrite_cp_refs_in_verification_type_info(stackmap_p, stackmap_end, 2152 calc_number_of_entries, frame_type, THREAD); 2153 } 2154 2155 // chop_frame { 2156 // u1 frame_type = CHOP; /* 248-250 */ 2157 // u2 offset_delta; 2158 // } 2159 else if (frame_type >= 248 && frame_type <= 250) { 2160 stackmap_p += 2; 2161 } 2162 2163 // same_frame_extended { 2164 // u1 frame_type = SAME_FRAME_EXTENDED; /* 251*/ 2165 // u2 offset_delta; 2166 // } 2167 else if (frame_type == 251) { 2168 stackmap_p += 2; 2169 } 2170 2171 // append_frame { 2172 // u1 frame_type = APPEND; /* 252-254 */ 2173 // u2 offset_delta; 2174 // verification_type_info locals[frame_type - 251]; 2175 // } 2176 else if (frame_type >= 252 && frame_type <= 254) { 2177 assert(stackmap_p + 2 <= stackmap_end, 2178 "no room for offset_delta"); 2179 stackmap_p += 2; 2180 u1 len = frame_type - 251; 2181 for (u1 i = 0; i < len; i++) { 2182 rewrite_cp_refs_in_verification_type_info(stackmap_p, stackmap_end, 2183 calc_number_of_entries, frame_type, THREAD); 2184 } 2185 } 2186 2187 // full_frame { 2188 // u1 frame_type = FULL_FRAME; /* 255 */ 2189 // u2 offset_delta; 2190 // u2 number_of_locals; 2191 // verification_type_info locals[number_of_locals]; 2192 // u2 number_of_stack_items; 2193 // verification_type_info stack[number_of_stack_items]; 2194 // } 2195 else if (frame_type == 255) { 2196 assert(stackmap_p + 2 + 2 <= stackmap_end, 2197 "no room for smallest full_frame"); 2198 stackmap_p += 2; 2199 2200 u2 number_of_locals = Bytes::get_Java_u2(stackmap_p); 2201 stackmap_p += 2; 2202 2203 for (u2 locals_i = 0; locals_i < number_of_locals; locals_i++) { 2204 rewrite_cp_refs_in_verification_type_info(stackmap_p, stackmap_end, 2205 calc_number_of_entries, frame_type, THREAD); 2206 } 2207 2208 // Use the largest size for the number_of_stack_items, but only get 2209 // the right number of bytes. 2210 u2 number_of_stack_items = Bytes::get_Java_u2(stackmap_p); 2211 stackmap_p += 2; 2212 2213 for (u2 stack_i = 0; stack_i < number_of_stack_items; stack_i++) { 2214 rewrite_cp_refs_in_verification_type_info(stackmap_p, stackmap_end, 2215 calc_number_of_entries, frame_type, THREAD); 2216 } 2217 } 2218 } // end while there is a stack_map_frame 2219 assert(number_of_entries == calc_number_of_entries, "sanity check"); 2220} // end rewrite_cp_refs_in_stack_map_table() 2221 2222 2223// Rewrite constant pool references in the verification type info 2224// portion of the method's stackmap table. These "structures" are 2225// adapted from the StackMapTable_attribute that is described in 2226// section 4.8.4 of the 6.0 version of the VM spec (dated 2005.10.26): 2227// file:///net/quincunx.sfbay/export/gbracha/ClassFile-Java6.pdf 2228// 2229// The verification_type_info structure is a u1 tag followed by 0 or 2230// more bytes of data: 2231// 2232// union verification_type_info { 2233// Top_variable_info; 2234// Integer_variable_info; 2235// Float_variable_info; 2236// Long_variable_info; 2237// Double_variable_info; 2238// Null_variable_info; 2239// UninitializedThis_variable_info; 2240// Object_variable_info; 2241// Uninitialized_variable_info; 2242// } 2243// 2244void VM_RedefineClasses::rewrite_cp_refs_in_verification_type_info( 2245 address& stackmap_p_ref, address stackmap_end, u2 frame_i, 2246 u1 frame_type, TRAPS) { 2247 2248 assert(stackmap_p_ref + 1 <= stackmap_end, "no room for tag"); 2249 u1 tag = *stackmap_p_ref; 2250 stackmap_p_ref++; 2251 2252 switch (tag) { 2253 // Top_variable_info { 2254 // u1 tag = ITEM_Top; /* 0 */ 2255 // } 2256 // verificationType.hpp has zero as ITEM_Bogus instead of ITEM_Top 2257 case 0: // fall through 2258 2259 // Integer_variable_info { 2260 // u1 tag = ITEM_Integer; /* 1 */ 2261 // } 2262 case ITEM_Integer: // fall through 2263 2264 // Float_variable_info { 2265 // u1 tag = ITEM_Float; /* 2 */ 2266 // } 2267 case ITEM_Float: // fall through 2268 2269 // Double_variable_info { 2270 // u1 tag = ITEM_Double; /* 3 */ 2271 // } 2272 case ITEM_Double: // fall through 2273 2274 // Long_variable_info { 2275 // u1 tag = ITEM_Long; /* 4 */ 2276 // } 2277 case ITEM_Long: // fall through 2278 2279 // Null_variable_info { 2280 // u1 tag = ITEM_Null; /* 5 */ 2281 // } 2282 case ITEM_Null: // fall through 2283 2284 // UninitializedThis_variable_info { 2285 // u1 tag = ITEM_UninitializedThis; /* 6 */ 2286 // } 2287 case ITEM_UninitializedThis: 2288 // nothing more to do for the above tag types 2289 break; 2290 2291 // Object_variable_info { 2292 // u1 tag = ITEM_Object; /* 7 */ 2293 // u2 cpool_index; 2294 // } 2295 case ITEM_Object: 2296 { 2297 assert(stackmap_p_ref + 2 <= stackmap_end, "no room for cpool_index"); 2298 u2 cpool_index = Bytes::get_Java_u2(stackmap_p_ref); 2299 u2 new_cp_index = find_new_index(cpool_index); 2300 if (new_cp_index != 0) { 2301 RC_TRACE_WITH_THREAD(0x04000000, THREAD, 2302 ("mapped old cpool_index=%d", cpool_index)); 2303 Bytes::put_Java_u2(stackmap_p_ref, new_cp_index); 2304 cpool_index = new_cp_index; 2305 } 2306 stackmap_p_ref += 2; 2307 2308 RC_TRACE_WITH_THREAD(0x04000000, THREAD, 2309 ("frame_i=%u, frame_type=%u, cpool_index=%d", frame_i, 2310 frame_type, cpool_index)); 2311 } break; 2312 2313 // Uninitialized_variable_info { 2314 // u1 tag = ITEM_Uninitialized; /* 8 */ 2315 // u2 offset; 2316 // } 2317 case ITEM_Uninitialized: 2318 assert(stackmap_p_ref + 2 <= stackmap_end, "no room for offset"); 2319 stackmap_p_ref += 2; 2320 break; 2321 2322 default: 2323 RC_TRACE_WITH_THREAD(0x04000000, THREAD, 2324 ("frame_i=%u, frame_type=%u, bad tag=0x%x", frame_i, frame_type, tag)); 2325 ShouldNotReachHere(); 2326 break; 2327 } // end switch (tag) 2328} // end rewrite_cp_refs_in_verification_type_info() 2329 2330 2331// Change the constant pool associated with klass scratch_class to 2332// scratch_cp. If shrink is true, then scratch_cp_length elements 2333// are copied from scratch_cp to a smaller constant pool and the 2334// smaller constant pool is associated with scratch_class. 2335void VM_RedefineClasses::set_new_constant_pool( 2336 instanceKlassHandle scratch_class, constantPoolHandle scratch_cp, 2337 int scratch_cp_length, bool shrink, TRAPS) { 2338 assert(!shrink || scratch_cp->length() >= scratch_cp_length, "sanity check"); 2339 2340 if (shrink) { 2341 // scratch_cp is a merged constant pool and has enough space for a 2342 // worst case merge situation. We want to associate the minimum 2343 // sized constant pool with the klass to save space. 2344 constantPoolHandle smaller_cp(THREAD, 2345 oopFactory::new_constantPool(scratch_cp_length, 2346 methodOopDesc::IsUnsafeConc, 2347 THREAD)); 2348 // preserve orig_length() value in the smaller copy 2349 int orig_length = scratch_cp->orig_length(); 2350 assert(orig_length != 0, "sanity check"); 2351 smaller_cp->set_orig_length(orig_length); 2352 scratch_cp->copy_cp_to(1, scratch_cp_length - 1, smaller_cp, 1, THREAD); 2353 scratch_cp = smaller_cp; 2354 smaller_cp()->set_is_conc_safe(true); 2355 } 2356 2357 // attach new constant pool to klass 2358 scratch_cp->set_pool_holder(scratch_class()); 2359 2360 // attach klass to new constant pool 2361 scratch_class->set_constants(scratch_cp()); 2362 2363 int i; // for portability 2364 2365 // update each field in klass to use new constant pool indices as needed 2366 typeArrayHandle fields(THREAD, scratch_class->fields()); 2367 int n_fields = fields->length(); 2368 for (i = 0; i < n_fields; i += instanceKlass::next_offset) { 2369 jshort cur_index = fields->short_at(i + instanceKlass::name_index_offset); 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 fields->short_at_put(i + instanceKlass::name_index_offset, new_index); 2375 } 2376 cur_index = fields->short_at(i + instanceKlass::signature_index_offset); 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 fields->short_at_put(i + instanceKlass::signature_index_offset, 2382 new_index); 2383 } 2384 cur_index = fields->short_at(i + instanceKlass::initval_index_offset); 2385 new_index = find_new_index(cur_index); 2386 if (new_index != 0) { 2387 RC_TRACE_WITH_THREAD(0x00080000, THREAD, 2388 ("field-initval_index change: %d to %d", cur_index, new_index)); 2389 fields->short_at_put(i + instanceKlass::initval_index_offset, new_index); 2390 } 2391 cur_index = fields->short_at(i + instanceKlass::generic_signature_offset); 2392 new_index = find_new_index(cur_index); 2393 if (new_index != 0) { 2394 RC_TRACE_WITH_THREAD(0x00080000, THREAD, 2395 ("field-generic_signature change: %d to %d", cur_index, new_index)); 2396 fields->short_at_put(i + instanceKlass::generic_signature_offset, 2397 new_index); 2398 } 2399 } // end for each field 2400 2401 // Update constant pool indices in the inner classes info to use 2402 // new constant indices as needed. The inner classes info is a 2403 // quadruple: 2404 // (inner_class_info, outer_class_info, inner_name, inner_access_flags) 2405 typeArrayOop inner_class_list = scratch_class->inner_classes(); 2406 int icl_length = (inner_class_list == NULL) ? 0 : inner_class_list->length(); 2407 if (icl_length > 0) { 2408 typeArrayHandle inner_class_list_h(THREAD, inner_class_list); 2409 for (int i = 0; i < icl_length; 2410 i += instanceKlass::inner_class_next_offset) { 2411 int cur_index = inner_class_list_h->ushort_at(i 2412 + instanceKlass::inner_class_inner_class_info_offset); 2413 if (cur_index == 0) { 2414 continue; // JVM spec. allows null inner class refs so skip it 2415 } 2416 int new_index = find_new_index(cur_index); 2417 if (new_index != 0) { 2418 RC_TRACE_WITH_THREAD(0x00080000, THREAD, 2419 ("inner_class_info change: %d to %d", cur_index, new_index)); 2420 inner_class_list_h->ushort_at_put(i 2421 + instanceKlass::inner_class_inner_class_info_offset, new_index); 2422 } 2423 cur_index = inner_class_list_h->ushort_at(i 2424 + instanceKlass::inner_class_outer_class_info_offset); 2425 new_index = find_new_index(cur_index); 2426 if (new_index != 0) { 2427 RC_TRACE_WITH_THREAD(0x00080000, THREAD, 2428 ("outer_class_info change: %d to %d", cur_index, new_index)); 2429 inner_class_list_h->ushort_at_put(i 2430 + instanceKlass::inner_class_outer_class_info_offset, new_index); 2431 } 2432 cur_index = inner_class_list_h->ushort_at(i 2433 + instanceKlass::inner_class_inner_name_offset); 2434 new_index = find_new_index(cur_index); 2435 if (new_index != 0) { 2436 RC_TRACE_WITH_THREAD(0x00080000, THREAD, 2437 ("inner_name change: %d to %d", cur_index, new_index)); 2438 inner_class_list_h->ushort_at_put(i 2439 + instanceKlass::inner_class_inner_name_offset, new_index); 2440 } 2441 } // end for each inner class 2442 } // end if we have inner classes 2443 2444 // Attach each method in klass to the new constant pool and update 2445 // to use new constant pool indices as needed: 2446 objArrayHandle methods(THREAD, scratch_class->methods()); 2447 for (i = methods->length() - 1; i >= 0; i--) { 2448 methodHandle method(THREAD, (methodOop)methods->obj_at(i)); 2449 method->set_constants(scratch_cp()); 2450 2451 int new_index = find_new_index(method->name_index()); 2452 if (new_index != 0) { 2453 RC_TRACE_WITH_THREAD(0x00080000, THREAD, 2454 ("method-name_index change: %d to %d", method->name_index(), 2455 new_index)); 2456 method->set_name_index(new_index); 2457 } 2458 new_index = find_new_index(method->signature_index()); 2459 if (new_index != 0) { 2460 RC_TRACE_WITH_THREAD(0x00080000, THREAD, 2461 ("method-signature_index change: %d to %d", 2462 method->signature_index(), new_index)); 2463 method->set_signature_index(new_index); 2464 } 2465 new_index = find_new_index(method->generic_signature_index()); 2466 if (new_index != 0) { 2467 RC_TRACE_WITH_THREAD(0x00080000, THREAD, 2468 ("method-generic_signature_index change: %d to %d", 2469 method->generic_signature_index(), new_index)); 2470 method->set_generic_signature_index(new_index); 2471 } 2472 2473 // Update constant pool indices in the method's checked exception 2474 // table to use new constant indices as needed. 2475 int cext_length = method->checked_exceptions_length(); 2476 if (cext_length > 0) { 2477 CheckedExceptionElement * cext_table = 2478 method->checked_exceptions_start(); 2479 for (int j = 0; j < cext_length; j++) { 2480 int cur_index = cext_table[j].class_cp_index; 2481 int new_index = find_new_index(cur_index); 2482 if (new_index != 0) { 2483 RC_TRACE_WITH_THREAD(0x00080000, THREAD, 2484 ("cext-class_cp_index change: %d to %d", cur_index, new_index)); 2485 cext_table[j].class_cp_index = (u2)new_index; 2486 } 2487 } // end for each checked exception table entry 2488 } // end if there are checked exception table entries 2489 2490 // Update each catch type index in the method's exception table 2491 // to use new constant pool indices as needed. The exception table 2492 // holds quadruple entries of the form: 2493 // (beg_bci, end_bci, handler_bci, klass_index) 2494 const int beg_bci_offset = 0; 2495 const int end_bci_offset = 1; 2496 const int handler_bci_offset = 2; 2497 const int klass_index_offset = 3; 2498 const int entry_size = 4; 2499 2500 typeArrayHandle ex_table (THREAD, method->exception_table()); 2501 int ext_length = ex_table->length(); 2502 assert(ext_length % entry_size == 0, "exception table format has changed"); 2503 2504 for (int j = 0; j < ext_length; j += entry_size) { 2505 int cur_index = ex_table->int_at(j + klass_index_offset); 2506 int new_index = find_new_index(cur_index); 2507 if (new_index != 0) { 2508 RC_TRACE_WITH_THREAD(0x00080000, THREAD, 2509 ("ext-klass_index change: %d to %d", cur_index, new_index)); 2510 ex_table->int_at_put(j + klass_index_offset, new_index); 2511 } 2512 } // end for each exception table entry 2513 2514 // Update constant pool indices in the method's local variable 2515 // table to use new constant indices as needed. The local variable 2516 // table hold sextuple entries of the form: 2517 // (start_pc, length, name_index, descriptor_index, signature_index, slot) 2518 int lvt_length = method->localvariable_table_length(); 2519 if (lvt_length > 0) { 2520 LocalVariableTableElement * lv_table = 2521 method->localvariable_table_start(); 2522 for (int j = 0; j < lvt_length; j++) { 2523 int cur_index = lv_table[j].name_cp_index; 2524 int new_index = find_new_index(cur_index); 2525 if (new_index != 0) { 2526 RC_TRACE_WITH_THREAD(0x00080000, THREAD, 2527 ("lvt-name_cp_index change: %d to %d", cur_index, new_index)); 2528 lv_table[j].name_cp_index = (u2)new_index; 2529 } 2530 cur_index = lv_table[j].descriptor_cp_index; 2531 new_index = find_new_index(cur_index); 2532 if (new_index != 0) { 2533 RC_TRACE_WITH_THREAD(0x00080000, THREAD, 2534 ("lvt-descriptor_cp_index change: %d to %d", cur_index, 2535 new_index)); 2536 lv_table[j].descriptor_cp_index = (u2)new_index; 2537 } 2538 cur_index = lv_table[j].signature_cp_index; 2539 new_index = find_new_index(cur_index); 2540 if (new_index != 0) { 2541 RC_TRACE_WITH_THREAD(0x00080000, THREAD, 2542 ("lvt-signature_cp_index change: %d to %d", cur_index, new_index)); 2543 lv_table[j].signature_cp_index = (u2)new_index; 2544 } 2545 } // end for each local variable table entry 2546 } // end if there are local variable table entries 2547 2548 rewrite_cp_refs_in_stack_map_table(method, THREAD); 2549 } // end for each method 2550 assert(scratch_cp()->is_conc_safe(), "Just checking"); 2551} // end set_new_constant_pool() 2552 2553 2554// Unevolving classes may point to methods of the_class directly 2555// from their constant pool caches, itables, and/or vtables. We 2556// use the SystemDictionary::classes_do() facility and this helper 2557// to fix up these pointers. 2558// 2559// Note: We currently don't support updating the vtable in 2560// arrayKlassOops. See Open Issues in jvmtiRedefineClasses.hpp. 2561void VM_RedefineClasses::adjust_cpool_cache_and_vtable(klassOop k_oop, 2562 oop initiating_loader, TRAPS) { 2563 Klass *k = k_oop->klass_part(); 2564 if (k->oop_is_instance()) { 2565 HandleMark hm(THREAD); 2566 instanceKlass *ik = (instanceKlass *) k; 2567 2568 // HotSpot specific optimization! HotSpot does not currently 2569 // support delegation from the bootstrap class loader to a 2570 // user-defined class loader. This means that if the bootstrap 2571 // class loader is the initiating class loader, then it will also 2572 // be the defining class loader. This also means that classes 2573 // loaded by the bootstrap class loader cannot refer to classes 2574 // loaded by a user-defined class loader. Note: a user-defined 2575 // class loader can delegate to the bootstrap class loader. 2576 // 2577 // If the current class being redefined has a user-defined class 2578 // loader as its defining class loader, then we can skip all 2579 // classes loaded by the bootstrap class loader. 2580 bool is_user_defined = 2581 instanceKlass::cast(_the_class_oop)->class_loader() != NULL; 2582 if (is_user_defined && ik->class_loader() == NULL) { 2583 return; 2584 } 2585 2586 // This is a very busy routine. We don't want too much tracing 2587 // printed out. 2588 bool trace_name_printed = false; 2589 2590 // Very noisy: only enable this call if you are trying to determine 2591 // that a specific class gets found by this routine. 2592 // RC_TRACE macro has an embedded ResourceMark 2593 // RC_TRACE_WITH_THREAD(0x00100000, THREAD, 2594 // ("adjust check: name=%s", ik->external_name())); 2595 // trace_name_printed = true; 2596 2597 // Fix the vtable embedded in the_class and subclasses of the_class, 2598 // if one exists. We discard scratch_class and we don't keep an 2599 // instanceKlass around to hold obsolete methods so we don't have 2600 // any other instanceKlass embedded vtables to update. The vtable 2601 // holds the methodOops for virtual (but not final) methods. 2602 if (ik->vtable_length() > 0 && ik->is_subtype_of(_the_class_oop)) { 2603 // ik->vtable() creates a wrapper object; rm cleans it up 2604 ResourceMark rm(THREAD); 2605 ik->vtable()->adjust_method_entries(_matching_old_methods, 2606 _matching_new_methods, 2607 _matching_methods_length, 2608 &trace_name_printed); 2609 } 2610 2611 // If the current class has an itable and we are either redefining an 2612 // interface or if the current class is a subclass of the_class, then 2613 // we potentially have to fix the itable. If we are redefining an 2614 // interface, then we have to call adjust_method_entries() for 2615 // every instanceKlass that has an itable since there isn't a 2616 // subclass relationship between an interface and an instanceKlass. 2617 if (ik->itable_length() > 0 && (Klass::cast(_the_class_oop)->is_interface() 2618 || ik->is_subclass_of(_the_class_oop))) { 2619 // ik->itable() creates a wrapper object; rm cleans it up 2620 ResourceMark rm(THREAD); 2621 ik->itable()->adjust_method_entries(_matching_old_methods, 2622 _matching_new_methods, 2623 _matching_methods_length, 2624 &trace_name_printed); 2625 } 2626 2627 // The constant pools in other classes (other_cp) can refer to 2628 // methods in the_class. We have to update method information in 2629 // other_cp's cache. If other_cp has a previous version, then we 2630 // have to repeat the process for each previous version. The 2631 // constant pool cache holds the methodOops for non-virtual 2632 // methods and for virtual, final methods. 2633 // 2634 // Special case: if the current class is the_class, then new_cp 2635 // has already been attached to the_class and old_cp has already 2636 // been added as a previous version. The new_cp doesn't have any 2637 // cached references to old methods so it doesn't need to be 2638 // updated. We can simply start with the previous version(s) in 2639 // that case. 2640 constantPoolHandle other_cp; 2641 constantPoolCacheOop cp_cache; 2642 2643 if (k_oop != _the_class_oop) { 2644 // this klass' constant pool cache may need adjustment 2645 other_cp = constantPoolHandle(ik->constants()); 2646 cp_cache = other_cp->cache(); 2647 if (cp_cache != NULL) { 2648 cp_cache->adjust_method_entries(_matching_old_methods, 2649 _matching_new_methods, 2650 _matching_methods_length, 2651 &trace_name_printed); 2652 } 2653 } 2654 { 2655 ResourceMark rm(THREAD); 2656 // PreviousVersionInfo objects returned via PreviousVersionWalker 2657 // contain a GrowableArray of handles. We have to clean up the 2658 // GrowableArray _after_ the PreviousVersionWalker destructor 2659 // has destroyed the handles. 2660 { 2661 // the previous versions' constant pool caches may need adjustment 2662 PreviousVersionWalker pvw(ik); 2663 for (PreviousVersionInfo * pv_info = pvw.next_previous_version(); 2664 pv_info != NULL; pv_info = pvw.next_previous_version()) { 2665 other_cp = pv_info->prev_constant_pool_handle(); 2666 cp_cache = other_cp->cache(); 2667 if (cp_cache != NULL) { 2668 cp_cache->adjust_method_entries(_matching_old_methods, 2669 _matching_new_methods, 2670 _matching_methods_length, 2671 &trace_name_printed); 2672 } 2673 } 2674 } // pvw is cleaned up 2675 } // rm is cleaned up 2676 } 2677} 2678 2679void VM_RedefineClasses::update_jmethod_ids() { 2680 for (int j = 0; j < _matching_methods_length; ++j) { 2681 methodOop old_method = _matching_old_methods[j]; 2682 jmethodID jmid = old_method->find_jmethod_id_or_null(); 2683 if (jmid != NULL) { 2684 // There is a jmethodID, change it to point to the new method 2685 methodHandle new_method_h(_matching_new_methods[j]); 2686 JNIHandles::change_method_associated_with_jmethod_id(jmid, new_method_h); 2687 assert(JNIHandles::resolve_jmethod_id(jmid) == _matching_new_methods[j], 2688 "should be replaced"); 2689 } 2690 } 2691} 2692 2693void VM_RedefineClasses::check_methods_and_mark_as_obsolete( 2694 BitMap *emcp_methods, int * emcp_method_count_p) { 2695 *emcp_method_count_p = 0; 2696 int obsolete_count = 0; 2697 int old_index = 0; 2698 for (int j = 0; j < _matching_methods_length; ++j, ++old_index) { 2699 methodOop old_method = _matching_old_methods[j]; 2700 methodOop new_method = _matching_new_methods[j]; 2701 methodOop old_array_method; 2702 2703 // Maintain an old_index into the _old_methods array by skipping 2704 // deleted methods 2705 while ((old_array_method = (methodOop) _old_methods->obj_at(old_index)) 2706 != old_method) { 2707 ++old_index; 2708 } 2709 2710 if (MethodComparator::methods_EMCP(old_method, new_method)) { 2711 // The EMCP definition from JSR-163 requires the bytecodes to be 2712 // the same with the exception of constant pool indices which may 2713 // differ. However, the constants referred to by those indices 2714 // must be the same. 2715 // 2716 // We use methods_EMCP() for comparison since constant pool 2717 // merging can remove duplicate constant pool entries that were 2718 // present in the old method and removed from the rewritten new 2719 // method. A faster binary comparison function would consider the 2720 // old and new methods to be different when they are actually 2721 // EMCP. 2722 // 2723 // The old and new methods are EMCP and you would think that we 2724 // could get rid of one of them here and now and save some space. 2725 // However, the concept of EMCP only considers the bytecodes and 2726 // the constant pool entries in the comparison. Other things, 2727 // e.g., the line number table (LNT) or the local variable table 2728 // (LVT) don't count in the comparison. So the new (and EMCP) 2729 // method can have a new LNT that we need so we can't just 2730 // overwrite the new method with the old method. 2731 // 2732 // When this routine is called, we have already attached the new 2733 // methods to the_class so the old methods are effectively 2734 // overwritten. However, if an old method is still executing, 2735 // then the old method cannot be collected until sometime after 2736 // the old method call has returned. So the overwriting of old 2737 // methods by new methods will save us space except for those 2738 // (hopefully few) old methods that are still executing. 2739 // 2740 // A method refers to a constMethodOop and this presents another 2741 // possible avenue to space savings. The constMethodOop in the 2742 // new method contains possibly new attributes (LNT, LVT, etc). 2743 // At first glance, it seems possible to save space by replacing 2744 // the constMethodOop in the old method with the constMethodOop 2745 // from the new method. The old and new methods would share the 2746 // same constMethodOop and we would save the space occupied by 2747 // the old constMethodOop. However, the constMethodOop contains 2748 // a back reference to the containing method. Sharing the 2749 // constMethodOop between two methods could lead to confusion in 2750 // the code that uses the back reference. This would lead to 2751 // brittle code that could be broken in non-obvious ways now or 2752 // in the future. 2753 // 2754 // Another possibility is to copy the constMethodOop from the new 2755 // method to the old method and then overwrite the new method with 2756 // the old method. Since the constMethodOop contains the bytecodes 2757 // for the method embedded in the oop, this option would change 2758 // the bytecodes out from under any threads executing the old 2759 // method and make the thread's bcp invalid. Since EMCP requires 2760 // that the bytecodes be the same modulo constant pool indices, it 2761 // is straight forward to compute the correct new bcp in the new 2762 // constMethodOop from the old bcp in the old constMethodOop. The 2763 // time consuming part would be searching all the frames in all 2764 // of the threads to find all of the calls to the old method. 2765 // 2766 // It looks like we will have to live with the limited savings 2767 // that we get from effectively overwriting the old methods 2768 // when the new methods are attached to the_class. 2769 2770 // track which methods are EMCP for add_previous_version() call 2771 emcp_methods->set_bit(old_index); 2772 (*emcp_method_count_p)++; 2773 2774 // An EMCP method is _not_ obsolete. An obsolete method has a 2775 // different jmethodID than the current method. An EMCP method 2776 // has the same jmethodID as the current method. Having the 2777 // same jmethodID for all EMCP versions of a method allows for 2778 // a consistent view of the EMCP methods regardless of which 2779 // EMCP method you happen to have in hand. For example, a 2780 // breakpoint set in one EMCP method will work for all EMCP 2781 // versions of the method including the current one. 2782 } else { 2783 // mark obsolete methods as such 2784 old_method->set_is_obsolete(); 2785 obsolete_count++; 2786 2787 // obsolete methods need a unique idnum 2788 u2 num = instanceKlass::cast(_the_class_oop)->next_method_idnum(); 2789 if (num != constMethodOopDesc::UNSET_IDNUM) { 2790// u2 old_num = old_method->method_idnum(); 2791 old_method->set_method_idnum(num); 2792// TO DO: attach obsolete annotations to obsolete method's new idnum 2793 } 2794 // With tracing we try not to "yack" too much. The position of 2795 // this trace assumes there are fewer obsolete methods than 2796 // EMCP methods. 2797 RC_TRACE(0x00000100, ("mark %s(%s) as obsolete", 2798 old_method->name()->as_C_string(), 2799 old_method->signature()->as_C_string())); 2800 } 2801 old_method->set_is_old(); 2802 } 2803 for (int i = 0; i < _deleted_methods_length; ++i) { 2804 methodOop old_method = _deleted_methods[i]; 2805 2806 assert(old_method->vtable_index() < 0, 2807 "cannot delete methods with vtable entries");; 2808 2809 // Mark all deleted methods as old and obsolete 2810 old_method->set_is_old(); 2811 old_method->set_is_obsolete(); 2812 ++obsolete_count; 2813 // With tracing we try not to "yack" too much. The position of 2814 // this trace assumes there are fewer obsolete methods than 2815 // EMCP methods. 2816 RC_TRACE(0x00000100, ("mark deleted %s(%s) as obsolete", 2817 old_method->name()->as_C_string(), 2818 old_method->signature()->as_C_string())); 2819 } 2820 assert((*emcp_method_count_p + obsolete_count) == _old_methods->length(), 2821 "sanity check"); 2822 RC_TRACE(0x00000100, ("EMCP_cnt=%d, obsolete_cnt=%d", *emcp_method_count_p, 2823 obsolete_count)); 2824} 2825 2826// This internal class transfers the native function registration from old methods 2827// to new methods. It is designed to handle both the simple case of unchanged 2828// native methods and the complex cases of native method prefixes being added and/or 2829// removed. 2830// It expects only to be used during the VM_RedefineClasses op (a safepoint). 2831// 2832// This class is used after the new methods have been installed in "the_class". 2833// 2834// So, for example, the following must be handled. Where 'm' is a method and 2835// a number followed by an underscore is a prefix. 2836// 2837// Old Name New Name 2838// Simple transfer to new method m -> m 2839// Add prefix m -> 1_m 2840// Remove prefix 1_m -> m 2841// Simultaneous add of prefixes m -> 3_2_1_m 2842// Simultaneous removal of prefixes 3_2_1_m -> m 2843// Simultaneous add and remove 1_m -> 2_m 2844// Same, caused by prefix removal only 3_2_1_m -> 3_2_m 2845// 2846class TransferNativeFunctionRegistration { 2847 private: 2848 instanceKlassHandle the_class; 2849 int prefix_count; 2850 char** prefixes; 2851 2852 // Recursively search the binary tree of possibly prefixed method names. 2853 // Iteration could be used if all agents were well behaved. Full tree walk is 2854 // more resilent to agents not cleaning up intermediate methods. 2855 // Branch at each depth in the binary tree is: 2856 // (1) without the prefix. 2857 // (2) with the prefix. 2858 // where 'prefix' is the prefix at that 'depth' (first prefix, second prefix,...) 2859 methodOop search_prefix_name_space(int depth, char* name_str, size_t name_len, 2860 symbolOop signature) { 2861 symbolOop name_symbol = SymbolTable::probe(name_str, (int)name_len); 2862 if (name_symbol != NULL) { 2863 methodOop method = Klass::cast(the_class())->lookup_method(name_symbol, signature); 2864 if (method != NULL) { 2865 // Even if prefixed, intermediate methods must exist. 2866 if (method->is_native()) { 2867 // Wahoo, we found a (possibly prefixed) version of the method, return it. 2868 return method; 2869 } 2870 if (depth < prefix_count) { 2871 // Try applying further prefixes (other than this one). 2872 method = search_prefix_name_space(depth+1, name_str, name_len, signature); 2873 if (method != NULL) { 2874 return method; // found 2875 } 2876 2877 // Try adding this prefix to the method name and see if it matches 2878 // another method name. 2879 char* prefix = prefixes[depth]; 2880 size_t prefix_len = strlen(prefix); 2881 size_t trial_len = name_len + prefix_len; 2882 char* trial_name_str = NEW_RESOURCE_ARRAY(char, trial_len + 1); 2883 strcpy(trial_name_str, prefix); 2884 strcat(trial_name_str, name_str); 2885 method = search_prefix_name_space(depth+1, trial_name_str, trial_len, 2886 signature); 2887 if (method != NULL) { 2888 // If found along this branch, it was prefixed, mark as such 2889 method->set_is_prefixed_native(); 2890 return method; // found 2891 } 2892 } 2893 } 2894 } 2895 return NULL; // This whole branch bore nothing 2896 } 2897 2898 // Return the method name with old prefixes stripped away. 2899 char* method_name_without_prefixes(methodOop method) { 2900 symbolOop name = method->name(); 2901 char* name_str = name->as_utf8(); 2902 2903 // Old prefixing may be defunct, strip prefixes, if any. 2904 for (int i = prefix_count-1; i >= 0; i--) { 2905 char* prefix = prefixes[i]; 2906 size_t prefix_len = strlen(prefix); 2907 if (strncmp(prefix, name_str, prefix_len) == 0) { 2908 name_str += prefix_len; 2909 } 2910 } 2911 return name_str; 2912 } 2913 2914 // Strip any prefixes off the old native method, then try to find a 2915 // (possibly prefixed) new native that matches it. 2916 methodOop strip_and_search_for_new_native(methodOop method) { 2917 ResourceMark rm; 2918 char* name_str = method_name_without_prefixes(method); 2919 return search_prefix_name_space(0, name_str, strlen(name_str), 2920 method->signature()); 2921 } 2922 2923 public: 2924 2925 // Construct a native method transfer processor for this class. 2926 TransferNativeFunctionRegistration(instanceKlassHandle _the_class) { 2927 assert(SafepointSynchronize::is_at_safepoint(), "sanity check"); 2928 2929 the_class = _the_class; 2930 prefixes = JvmtiExport::get_all_native_method_prefixes(&prefix_count); 2931 } 2932 2933 // Attempt to transfer any of the old or deleted methods that are native 2934 void transfer_registrations(methodOop* old_methods, int methods_length) { 2935 for (int j = 0; j < methods_length; j++) { 2936 methodOop old_method = old_methods[j]; 2937 2938 if (old_method->is_native() && old_method->has_native_function()) { 2939 methodOop new_method = strip_and_search_for_new_native(old_method); 2940 if (new_method != NULL) { 2941 // Actually set the native function in the new method. 2942 // Redefine does not send events (except CFLH), certainly not this 2943 // behind the scenes re-registration. 2944 new_method->set_native_function(old_method->native_function(), 2945 !methodOopDesc::native_bind_event_is_interesting); 2946 } 2947 } 2948 } 2949 } 2950}; 2951 2952// Don't lose the association between a native method and its JNI function. 2953void VM_RedefineClasses::transfer_old_native_function_registrations(instanceKlassHandle the_class) { 2954 TransferNativeFunctionRegistration transfer(the_class); 2955 transfer.transfer_registrations(_deleted_methods, _deleted_methods_length); 2956 transfer.transfer_registrations(_matching_old_methods, _matching_methods_length); 2957} 2958 2959// Deoptimize all compiled code that depends on this class. 2960// 2961// If the can_redefine_classes capability is obtained in the onload 2962// phase then the compiler has recorded all dependencies from startup. 2963// In that case we need only deoptimize and throw away all compiled code 2964// that depends on the class. 2965// 2966// If can_redefine_classes is obtained sometime after the onload 2967// phase then the dependency information may be incomplete. In that case 2968// the first call to RedefineClasses causes all compiled code to be 2969// thrown away. As can_redefine_classes has been obtained then 2970// all future compilations will record dependencies so second and 2971// subsequent calls to RedefineClasses need only throw away code 2972// that depends on the class. 2973// 2974void VM_RedefineClasses::flush_dependent_code(instanceKlassHandle k_h, TRAPS) { 2975 assert_locked_or_safepoint(Compile_lock); 2976 2977 // All dependencies have been recorded from startup or this is a second or 2978 // subsequent use of RedefineClasses 2979 if (JvmtiExport::all_dependencies_are_recorded()) { 2980 Universe::flush_evol_dependents_on(k_h); 2981 } else { 2982 CodeCache::mark_all_nmethods_for_deoptimization(); 2983 2984 ResourceMark rm(THREAD); 2985 DeoptimizationMarker dm; 2986 2987 // Deoptimize all activations depending on marked nmethods 2988 Deoptimization::deoptimize_dependents(); 2989 2990 // Make the dependent methods not entrant (in VM_Deoptimize they are made zombies) 2991 CodeCache::make_marked_nmethods_not_entrant(); 2992 2993 // From now on we know that the dependency information is complete 2994 JvmtiExport::set_all_dependencies_are_recorded(true); 2995 } 2996} 2997 2998void VM_RedefineClasses::compute_added_deleted_matching_methods() { 2999 methodOop old_method; 3000 methodOop new_method; 3001 3002 _matching_old_methods = NEW_RESOURCE_ARRAY(methodOop, _old_methods->length()); 3003 _matching_new_methods = NEW_RESOURCE_ARRAY(methodOop, _old_methods->length()); 3004 _added_methods = NEW_RESOURCE_ARRAY(methodOop, _new_methods->length()); 3005 _deleted_methods = NEW_RESOURCE_ARRAY(methodOop, _old_methods->length()); 3006 3007 _matching_methods_length = 0; 3008 _deleted_methods_length = 0; 3009 _added_methods_length = 0; 3010 3011 int nj = 0; 3012 int oj = 0; 3013 while (true) { 3014 if (oj >= _old_methods->length()) { 3015 if (nj >= _new_methods->length()) { 3016 break; // we've looked at everything, done 3017 } 3018 // New method at the end 3019 new_method = (methodOop) _new_methods->obj_at(nj); 3020 _added_methods[_added_methods_length++] = new_method; 3021 ++nj; 3022 } else if (nj >= _new_methods->length()) { 3023 // Old method, at the end, is deleted 3024 old_method = (methodOop) _old_methods->obj_at(oj); 3025 _deleted_methods[_deleted_methods_length++] = old_method; 3026 ++oj; 3027 } else { 3028 old_method = (methodOop) _old_methods->obj_at(oj); 3029 new_method = (methodOop) _new_methods->obj_at(nj); 3030 if (old_method->name() == new_method->name()) { 3031 if (old_method->signature() == new_method->signature()) { 3032 _matching_old_methods[_matching_methods_length ] = old_method; 3033 _matching_new_methods[_matching_methods_length++] = new_method; 3034 ++nj; 3035 ++oj; 3036 } else { 3037 // added overloaded have already been moved to the end, 3038 // so this is a deleted overloaded method 3039 _deleted_methods[_deleted_methods_length++] = old_method; 3040 ++oj; 3041 } 3042 } else { // names don't match 3043 if (old_method->name()->fast_compare(new_method->name()) > 0) { 3044 // new method 3045 _added_methods[_added_methods_length++] = new_method; 3046 ++nj; 3047 } else { 3048 // deleted method 3049 _deleted_methods[_deleted_methods_length++] = old_method; 3050 ++oj; 3051 } 3052 } 3053 } 3054 } 3055 assert(_matching_methods_length + _deleted_methods_length == _old_methods->length(), "sanity"); 3056 assert(_matching_methods_length + _added_methods_length == _new_methods->length(), "sanity"); 3057} 3058 3059 3060 3061// Install the redefinition of a class: 3062// - house keeping (flushing breakpoints and caches, deoptimizing 3063// dependent compiled code) 3064// - replacing parts in the_class with parts from scratch_class 3065// - adding a weak reference to track the obsolete but interesting 3066// parts of the_class 3067// - adjusting constant pool caches and vtables in other classes 3068// that refer to methods in the_class. These adjustments use the 3069// SystemDictionary::classes_do() facility which only allows 3070// a helper method to be specified. The interesting parameters 3071// that we would like to pass to the helper method are saved in 3072// static global fields in the VM operation. 3073void VM_RedefineClasses::redefine_single_class(jclass the_jclass, 3074 instanceKlassHandle scratch_class, TRAPS) { 3075 3076 RC_TIMER_START(_timer_rsc_phase1); 3077 3078 oop the_class_mirror = JNIHandles::resolve_non_null(the_jclass); 3079 klassOop the_class_oop = java_lang_Class::as_klassOop(the_class_mirror); 3080 instanceKlassHandle the_class = instanceKlassHandle(THREAD, the_class_oop); 3081 3082#ifndef JVMTI_KERNEL 3083 // Remove all breakpoints in methods of this class 3084 JvmtiBreakpoints& jvmti_breakpoints = JvmtiCurrentBreakpoints::get_jvmti_breakpoints(); 3085 jvmti_breakpoints.clearall_in_class_at_safepoint(the_class_oop); 3086#endif // !JVMTI_KERNEL 3087 3088 if (the_class_oop == Universe::reflect_invoke_cache()->klass()) { 3089 // We are redefining java.lang.reflect.Method. Method.invoke() is 3090 // cached and users of the cache care about each active version of 3091 // the method so we have to track this previous version. 3092 // Do this before methods get switched 3093 Universe::reflect_invoke_cache()->add_previous_version( 3094 the_class->method_with_idnum(Universe::reflect_invoke_cache()->method_idnum())); 3095 } 3096 3097 // Deoptimize all compiled code that depends on this class 3098 flush_dependent_code(the_class, THREAD); 3099 3100 _old_methods = the_class->methods(); 3101 _new_methods = scratch_class->methods(); 3102 _the_class_oop = the_class_oop; 3103 compute_added_deleted_matching_methods(); 3104 update_jmethod_ids(); 3105 3106 // Attach new constant pool to the original klass. The original 3107 // klass still refers to the old constant pool (for now). 3108 scratch_class->constants()->set_pool_holder(the_class()); 3109 3110#if 0 3111 // In theory, with constant pool merging in place we should be able 3112 // to save space by using the new, merged constant pool in place of 3113 // the old constant pool(s). By "pool(s)" I mean the constant pool in 3114 // the klass version we are replacing now and any constant pool(s) in 3115 // previous versions of klass. Nice theory, doesn't work in practice. 3116 // When this code is enabled, even simple programs throw NullPointer 3117 // exceptions. I'm guessing that this is caused by some constant pool 3118 // cache difference between the new, merged constant pool and the 3119 // constant pool that was just being used by the klass. I'm keeping 3120 // this code around to archive the idea, but the code has to remain 3121 // disabled for now. 3122 3123 // Attach each old method to the new constant pool. This can be 3124 // done here since we are past the bytecode verification and 3125 // constant pool optimization phases. 3126 for (int i = _old_methods->length() - 1; i >= 0; i--) { 3127 methodOop method = (methodOop)_old_methods->obj_at(i); 3128 method->set_constants(scratch_class->constants()); 3129 } 3130 3131 { 3132 // walk all previous versions of the klass 3133 instanceKlass *ik = (instanceKlass *)the_class()->klass_part(); 3134 PreviousVersionWalker pvw(ik); 3135 instanceKlassHandle ikh; 3136 do { 3137 ikh = pvw.next_previous_version(); 3138 if (!ikh.is_null()) { 3139 ik = ikh(); 3140 3141 // attach previous version of klass to the new constant pool 3142 ik->set_constants(scratch_class->constants()); 3143 3144 // Attach each method in the previous version of klass to the 3145 // new constant pool 3146 objArrayOop prev_methods = ik->methods(); 3147 for (int i = prev_methods->length() - 1; i >= 0; i--) { 3148 methodOop method = (methodOop)prev_methods->obj_at(i); 3149 method->set_constants(scratch_class->constants()); 3150 } 3151 } 3152 } while (!ikh.is_null()); 3153 } 3154#endif 3155 3156 // Replace methods and constantpool 3157 the_class->set_methods(_new_methods); 3158 scratch_class->set_methods(_old_methods); // To prevent potential GCing of the old methods, 3159 // and to be able to undo operation easily. 3160 3161 constantPoolOop old_constants = the_class->constants(); 3162 the_class->set_constants(scratch_class->constants()); 3163 scratch_class->set_constants(old_constants); // See the previous comment. 3164#if 0 3165 // We are swapping the guts of "the new class" with the guts of "the 3166 // class". Since the old constant pool has just been attached to "the 3167 // new class", it seems logical to set the pool holder in the old 3168 // constant pool also. However, doing this will change the observable 3169 // class hierarchy for any old methods that are still executing. A 3170 // method can query the identity of its "holder" and this query uses 3171 // the method's constant pool link to find the holder. The change in 3172 // holding class from "the class" to "the new class" can confuse 3173 // things. 3174 // 3175 // Setting the old constant pool's holder will also cause 3176 // verification done during vtable initialization below to fail. 3177 // During vtable initialization, the vtable's class is verified to be 3178 // a subtype of the method's holder. The vtable's class is "the 3179 // class" and the method's holder is gotten from the constant pool 3180 // link in the method itself. For "the class"'s directly implemented 3181 // methods, the method holder is "the class" itself (as gotten from 3182 // the new constant pool). The check works fine in this case. The 3183 // check also works fine for methods inherited from super classes. 3184 // 3185 // Miranda methods are a little more complicated. A miranda method is 3186 // provided by an interface when the class implementing the interface 3187 // does not provide its own method. These interfaces are implemented 3188 // internally as an instanceKlass. These special instanceKlasses 3189 // share the constant pool of the class that "implements" the 3190 // interface. By sharing the constant pool, the method holder of a 3191 // miranda method is the class that "implements" the interface. In a 3192 // non-redefine situation, the subtype check works fine. However, if 3193 // the old constant pool's pool holder is modified, then the check 3194 // fails because there is no class hierarchy relationship between the 3195 // vtable's class and "the new class". 3196 3197 old_constants->set_pool_holder(scratch_class()); 3198#endif 3199 3200 // track which methods are EMCP for add_previous_version() call below 3201 BitMap emcp_methods(_old_methods->length()); 3202 int emcp_method_count = 0; 3203 emcp_methods.clear(); // clears 0..(length() - 1) 3204 check_methods_and_mark_as_obsolete(&emcp_methods, &emcp_method_count); 3205 transfer_old_native_function_registrations(the_class); 3206 3207 // The class file bytes from before any retransformable agents mucked 3208 // with them was cached on the scratch class, move to the_class. 3209 // Note: we still want to do this if nothing needed caching since it 3210 // should get cleared in the_class too. 3211 the_class->set_cached_class_file(scratch_class->get_cached_class_file_bytes(), 3212 scratch_class->get_cached_class_file_len()); 3213 3214 // Replace inner_classes 3215 typeArrayOop old_inner_classes = the_class->inner_classes(); 3216 the_class->set_inner_classes(scratch_class->inner_classes()); 3217 scratch_class->set_inner_classes(old_inner_classes); 3218 3219 // Initialize the vtable and interface table after 3220 // methods have been rewritten 3221 { 3222 ResourceMark rm(THREAD); 3223 // no exception should happen here since we explicitly 3224 // do not check loader constraints. 3225 // compare_and_normalize_class_versions has already checked: 3226 // - classloaders unchanged, signatures unchanged 3227 // - all instanceKlasses for redefined classes reused & contents updated 3228 the_class->vtable()->initialize_vtable(false, THREAD); 3229 the_class->itable()->initialize_itable(false, THREAD); 3230 assert(!HAS_PENDING_EXCEPTION || (THREAD->pending_exception()->is_a(SystemDictionary::ThreadDeath_klass())), "redefine exception"); 3231 } 3232 3233 // Leave arrays of jmethodIDs and itable index cache unchanged 3234 3235 // Copy the "source file name" attribute from new class version 3236 the_class->set_source_file_name(scratch_class->source_file_name()); 3237 3238 // Copy the "source debug extension" attribute from new class version 3239 the_class->set_source_debug_extension( 3240 scratch_class->source_debug_extension()); 3241 3242 // Use of javac -g could be different in the old and the new 3243 if (scratch_class->access_flags().has_localvariable_table() != 3244 the_class->access_flags().has_localvariable_table()) { 3245 3246 AccessFlags flags = the_class->access_flags(); 3247 if (scratch_class->access_flags().has_localvariable_table()) { 3248 flags.set_has_localvariable_table(); 3249 } else { 3250 flags.clear_has_localvariable_table(); 3251 } 3252 the_class->set_access_flags(flags); 3253 } 3254 3255 // Replace class annotation fields values 3256 typeArrayOop old_class_annotations = the_class->class_annotations(); 3257 the_class->set_class_annotations(scratch_class->class_annotations()); 3258 scratch_class->set_class_annotations(old_class_annotations); 3259 3260 // Replace fields annotation fields values 3261 objArrayOop old_fields_annotations = the_class->fields_annotations(); 3262 the_class->set_fields_annotations(scratch_class->fields_annotations()); 3263 scratch_class->set_fields_annotations(old_fields_annotations); 3264 3265 // Replace methods annotation fields values 3266 objArrayOop old_methods_annotations = the_class->methods_annotations(); 3267 the_class->set_methods_annotations(scratch_class->methods_annotations()); 3268 scratch_class->set_methods_annotations(old_methods_annotations); 3269 3270 // Replace methods parameter annotation fields values 3271 objArrayOop old_methods_parameter_annotations = 3272 the_class->methods_parameter_annotations(); 3273 the_class->set_methods_parameter_annotations( 3274 scratch_class->methods_parameter_annotations()); 3275 scratch_class->set_methods_parameter_annotations(old_methods_parameter_annotations); 3276 3277 // Replace methods default annotation fields values 3278 objArrayOop old_methods_default_annotations = 3279 the_class->methods_default_annotations(); 3280 the_class->set_methods_default_annotations( 3281 scratch_class->methods_default_annotations()); 3282 scratch_class->set_methods_default_annotations(old_methods_default_annotations); 3283 3284 // Replace minor version number of class file 3285 u2 old_minor_version = the_class->minor_version(); 3286 the_class->set_minor_version(scratch_class->minor_version()); 3287 scratch_class->set_minor_version(old_minor_version); 3288 3289 // Replace major version number of class file 3290 u2 old_major_version = the_class->major_version(); 3291 the_class->set_major_version(scratch_class->major_version()); 3292 scratch_class->set_major_version(old_major_version); 3293 3294 // Replace CP indexes for class and name+type of enclosing method 3295 u2 old_class_idx = the_class->enclosing_method_class_index(); 3296 u2 old_method_idx = the_class->enclosing_method_method_index(); 3297 the_class->set_enclosing_method_indices( 3298 scratch_class->enclosing_method_class_index(), 3299 scratch_class->enclosing_method_method_index()); 3300 scratch_class->set_enclosing_method_indices(old_class_idx, old_method_idx); 3301 3302 // keep track of previous versions of this class 3303 the_class->add_previous_version(scratch_class, &emcp_methods, 3304 emcp_method_count); 3305 3306 RC_TIMER_STOP(_timer_rsc_phase1); 3307 RC_TIMER_START(_timer_rsc_phase2); 3308 3309 // Adjust constantpool caches and vtables for all classes 3310 // that reference methods of the evolved class. 3311 SystemDictionary::classes_do(adjust_cpool_cache_and_vtable, THREAD); 3312 3313 if (the_class->oop_map_cache() != NULL) { 3314 // Flush references to any obsolete methods from the oop map cache 3315 // so that obsolete methods are not pinned. 3316 the_class->oop_map_cache()->flush_obsolete_entries(); 3317 } 3318 3319 // increment the classRedefinedCount field in the_class and in any 3320 // direct and indirect subclasses of the_class 3321 increment_class_counter((instanceKlass *)the_class()->klass_part(), THREAD); 3322 3323 // RC_TRACE macro has an embedded ResourceMark 3324 RC_TRACE_WITH_THREAD(0x00000001, THREAD, 3325 ("redefined name=%s, count=%d (avail_mem=" UINT64_FORMAT "K)", 3326 the_class->external_name(), 3327 java_lang_Class::classRedefinedCount(the_class_mirror), 3328 os::available_memory() >> 10)); 3329 3330 RC_TIMER_STOP(_timer_rsc_phase2); 3331} // end redefine_single_class() 3332 3333 3334// Increment the classRedefinedCount field in the specific instanceKlass 3335// and in all direct and indirect subclasses. 3336void VM_RedefineClasses::increment_class_counter(instanceKlass *ik, TRAPS) { 3337 oop class_mirror = ik->java_mirror(); 3338 klassOop class_oop = java_lang_Class::as_klassOop(class_mirror); 3339 int new_count = java_lang_Class::classRedefinedCount(class_mirror) + 1; 3340 java_lang_Class::set_classRedefinedCount(class_mirror, new_count); 3341 3342 if (class_oop != _the_class_oop) { 3343 // _the_class_oop count is printed at end of redefine_single_class() 3344 RC_TRACE_WITH_THREAD(0x00000008, THREAD, 3345 ("updated count in subclass=%s to %d", ik->external_name(), new_count)); 3346 } 3347 3348 for (Klass *subk = ik->subklass(); subk != NULL; 3349 subk = subk->next_sibling()) { 3350 klassOop sub = subk->as_klassOop(); 3351 instanceKlass *subik = (instanceKlass *)sub->klass_part(); 3352 3353 // recursively do subclasses of the current subclass 3354 increment_class_counter(subik, THREAD); 3355 } 3356} 3357 3358#ifndef PRODUCT 3359void 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 3378void 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 3431