1 /* 2 * Copyright (c) 2003, 2014, 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/metadataOnStackMark.hpp" 27 #include "classfile/systemDictionary.hpp" 28 #include "classfile/verifier.hpp" 29 #include "code/codeCache.hpp" 30 #include "compiler/compileBroker.hpp" 31 #include "interpreter/oopMapCache.hpp" 32 #include "interpreter/rewriter.hpp" 33 #include "memory/gcLocker.hpp" 34 #include "memory/metadataFactory.hpp" 35 #include "memory/metaspaceShared.hpp" 36 #include "memory/universe.inline.hpp" 37 #include "oops/fieldStreams.hpp" 38 #include "oops/klassVtable.hpp" 39 #include "prims/jvmtiImpl.hpp" 40 #include "prims/jvmtiRedefineClasses.hpp" 41 #include "prims/methodComparator.hpp" 42 #include "runtime/deoptimization.hpp" 43 #include "runtime/relocator.hpp" 44 #include "utilities/bitMap.inline.hpp" 45 46 PRAGMA_FORMAT_MUTE_WARNINGS_FOR_GCC 47 48 Array<Method*>* VM_RedefineClasses::_old_methods = NULL; 49 Array<Method*>* VM_RedefineClasses::_new_methods = NULL; 50 Method** VM_RedefineClasses::_matching_old_methods = NULL; 51 Method** VM_RedefineClasses::_matching_new_methods = NULL; 52 Method** VM_RedefineClasses::_deleted_methods = NULL; 53 Method** VM_RedefineClasses::_added_methods = NULL; 54 int VM_RedefineClasses::_matching_methods_length = 0; 55 int VM_RedefineClasses::_deleted_methods_length = 0; 56 int VM_RedefineClasses::_added_methods_length = 0; 57 Klass* VM_RedefineClasses::_the_class_oop = NULL; 58 59 60 VM_RedefineClasses::VM_RedefineClasses(jint class_count, 61 const jvmtiClassDefinition *class_defs, 62 JvmtiClassLoadKind class_load_kind) { 63 _class_count = class_count; 64 _class_defs = class_defs; 65 _class_load_kind = class_load_kind; 66 _res = JVMTI_ERROR_NONE; 67 } 68 69 bool VM_RedefineClasses::doit_prologue() { 70 if (_class_count == 0) { 71 _res = JVMTI_ERROR_NONE; 72 return false; 73 } 74 if (_class_defs == NULL) { 75 _res = JVMTI_ERROR_NULL_POINTER; 76 return false; 77 } 78 for (int i = 0; i < _class_count; i++) { 79 if (_class_defs[i].klass == NULL) { 80 _res = JVMTI_ERROR_INVALID_CLASS; 81 return false; 82 } 83 if (_class_defs[i].class_byte_count == 0) { 84 _res = JVMTI_ERROR_INVALID_CLASS_FORMAT; 85 return false; 86 } 87 if (_class_defs[i].class_bytes == NULL) { 88 _res = JVMTI_ERROR_NULL_POINTER; 89 return false; 90 } 91 } 92 93 // Start timer after all the sanity checks; not quite accurate, but 94 // better than adding a bunch of stop() calls. 95 RC_TIMER_START(_timer_vm_op_prologue); 96 97 // We first load new class versions in the prologue, because somewhere down the 98 // call chain it is required that the current thread is a Java thread. 99 _res = load_new_class_versions(Thread::current()); 100 if (_res != JVMTI_ERROR_NONE) { 101 // free any successfully created classes, since none are redefined 102 for (int i = 0; i < _class_count; i++) { 103 if (_scratch_classes[i] != NULL) { 104 ClassLoaderData* cld = _scratch_classes[i]->class_loader_data(); 105 // Free the memory for this class at class unloading time. Not before 106 // because CMS might think this is still live. 107 cld->add_to_deallocate_list((InstanceKlass*)_scratch_classes[i]); 108 } 109 } 110 // Free os::malloc allocated memory in load_new_class_version. 111 os::free(_scratch_classes); 112 RC_TIMER_STOP(_timer_vm_op_prologue); 113 return false; 114 } 115 116 RC_TIMER_STOP(_timer_vm_op_prologue); 117 return true; 118 } 119 120 void VM_RedefineClasses::doit() { 121 Thread *thread = Thread::current(); 122 123 if (UseSharedSpaces) { 124 // Sharing is enabled so we remap the shared readonly space to 125 // shared readwrite, private just in case we need to redefine 126 // a shared class. We do the remap during the doit() phase of 127 // the safepoint to be safer. 128 if (!MetaspaceShared::remap_shared_readonly_as_readwrite()) { 129 RC_TRACE_WITH_THREAD(0x00000001, thread, 130 ("failed to remap shared readonly space to readwrite, private")); 131 _res = JVMTI_ERROR_INTERNAL; 132 return; 133 } 134 } 135 136 // Mark methods seen on stack and everywhere else so old methods are not 137 // cleaned up if they're on the stack. 138 MetadataOnStackMark md_on_stack(true); 139 HandleMark hm(thread); // make sure any handles created are deleted 140 // before the stack walk again. 141 142 for (int i = 0; i < _class_count; i++) { 143 redefine_single_class(_class_defs[i].klass, _scratch_classes[i], thread); 144 ClassLoaderData* cld = _scratch_classes[i]->class_loader_data(); 145 // Free the memory for this class at class unloading time. Not before 146 // because CMS might think this is still live. 147 cld->add_to_deallocate_list((InstanceKlass*)_scratch_classes[i]); 148 _scratch_classes[i] = NULL; 149 } 150 151 // Disable any dependent concurrent compilations 152 SystemDictionary::notice_modification(); 153 154 // Set flag indicating that some invariants are no longer true. 155 // See jvmtiExport.hpp for detailed explanation. 156 JvmtiExport::set_has_redefined_a_class(); 157 158 // check_class() is optionally called for product bits, but is 159 // always called for non-product bits. 160 #ifdef PRODUCT 161 if (RC_TRACE_ENABLED(0x00004000)) { 162 #endif 163 RC_TRACE_WITH_THREAD(0x00004000, thread, ("calling check_class")); 164 CheckClass check_class(thread); 165 ClassLoaderDataGraph::classes_do(&check_class); 166 #ifdef PRODUCT 167 } 168 #endif 169 } 170 171 void VM_RedefineClasses::doit_epilogue() { 172 // Free os::malloc allocated memory. 173 os::free(_scratch_classes); 174 175 if (RC_TRACE_ENABLED(0x00000004)) { 176 // Used to have separate timers for "doit" and "all", but the timer 177 // overhead skewed the measurements. 178 jlong doit_time = _timer_rsc_phase1.milliseconds() + 179 _timer_rsc_phase2.milliseconds(); 180 jlong all_time = _timer_vm_op_prologue.milliseconds() + doit_time; 181 182 RC_TRACE(0x00000004, ("vm_op: all=" UINT64_FORMAT 183 " prologue=" UINT64_FORMAT " doit=" UINT64_FORMAT, all_time, 184 _timer_vm_op_prologue.milliseconds(), doit_time)); 185 RC_TRACE(0x00000004, 186 ("redefine_single_class: phase1=" UINT64_FORMAT " phase2=" UINT64_FORMAT, 187 _timer_rsc_phase1.milliseconds(), _timer_rsc_phase2.milliseconds())); 188 } 189 } 190 191 bool VM_RedefineClasses::is_modifiable_class(oop klass_mirror) { 192 // classes for primitives cannot be redefined 193 if (java_lang_Class::is_primitive(klass_mirror)) { 194 return false; 195 } 196 Klass* the_class_oop = java_lang_Class::as_Klass(klass_mirror); 197 // classes for arrays cannot be redefined 198 if (the_class_oop == NULL || !the_class_oop->oop_is_instance()) { 199 return false; 200 } 201 return true; 202 } 203 204 // Append the current entry at scratch_i in scratch_cp to *merge_cp_p 205 // where the end of *merge_cp_p is specified by *merge_cp_length_p. For 206 // direct CP entries, there is just the current entry to append. For 207 // indirect and double-indirect CP entries, there are zero or more 208 // referenced CP entries along with the current entry to append. 209 // Indirect and double-indirect CP entries are handled by recursive 210 // calls to append_entry() as needed. The referenced CP entries are 211 // always appended to *merge_cp_p before the referee CP entry. These 212 // referenced CP entries may already exist in *merge_cp_p in which case 213 // there is nothing extra to append and only the current entry is 214 // appended. 215 void VM_RedefineClasses::append_entry(constantPoolHandle scratch_cp, 216 int scratch_i, constantPoolHandle *merge_cp_p, int *merge_cp_length_p, 217 TRAPS) { 218 219 // append is different depending on entry tag type 220 switch (scratch_cp->tag_at(scratch_i).value()) { 221 222 // The old verifier is implemented outside the VM. It loads classes, 223 // but does not resolve constant pool entries directly so we never 224 // see Class entries here with the old verifier. Similarly the old 225 // verifier does not like Class entries in the input constant pool. 226 // The split-verifier is implemented in the VM so it can optionally 227 // and directly resolve constant pool entries to load classes. The 228 // split-verifier can accept either Class entries or UnresolvedClass 229 // entries in the input constant pool. We revert the appended copy 230 // back to UnresolvedClass so that either verifier will be happy 231 // with the constant pool entry. 232 case JVM_CONSTANT_Class: 233 { 234 // revert the copy to JVM_CONSTANT_UnresolvedClass 235 (*merge_cp_p)->unresolved_klass_at_put(*merge_cp_length_p, 236 scratch_cp->klass_name_at(scratch_i)); 237 238 if (scratch_i != *merge_cp_length_p) { 239 // The new entry in *merge_cp_p is at a different index than 240 // the new entry in scratch_cp so we need to map the index values. 241 map_index(scratch_cp, scratch_i, *merge_cp_length_p); 242 } 243 (*merge_cp_length_p)++; 244 } break; 245 246 // these are direct CP entries so they can be directly appended, 247 // but double and long take two constant pool entries 248 case JVM_CONSTANT_Double: // fall through 249 case JVM_CONSTANT_Long: 250 { 251 ConstantPool::copy_entry_to(scratch_cp, scratch_i, *merge_cp_p, *merge_cp_length_p, 252 THREAD); 253 254 if (scratch_i != *merge_cp_length_p) { 255 // The new entry in *merge_cp_p is at a different index than 256 // the new entry in scratch_cp so we need to map the index values. 257 map_index(scratch_cp, scratch_i, *merge_cp_length_p); 258 } 259 (*merge_cp_length_p) += 2; 260 } break; 261 262 // these are direct CP entries so they can be directly appended 263 case JVM_CONSTANT_Float: // fall through 264 case JVM_CONSTANT_Integer: // fall through 265 case JVM_CONSTANT_Utf8: // fall through 266 267 // This was an indirect CP entry, but it has been changed into 268 // Symbol*s so this entry can be directly appended. 269 case JVM_CONSTANT_String: // fall through 270 271 // These were indirect CP entries, but they have been changed into 272 // Symbol*s so these entries can be directly appended. 273 case JVM_CONSTANT_UnresolvedClass: // fall through 274 { 275 ConstantPool::copy_entry_to(scratch_cp, scratch_i, *merge_cp_p, *merge_cp_length_p, 276 THREAD); 277 278 if (scratch_i != *merge_cp_length_p) { 279 // The new entry in *merge_cp_p is at a different index than 280 // the new entry in scratch_cp so we need to map the index values. 281 map_index(scratch_cp, scratch_i, *merge_cp_length_p); 282 } 283 (*merge_cp_length_p)++; 284 } break; 285 286 // this is an indirect CP entry so it needs special handling 287 case JVM_CONSTANT_NameAndType: 288 { 289 int name_ref_i = scratch_cp->name_ref_index_at(scratch_i); 290 int new_name_ref_i = find_or_append_indirect_entry(scratch_cp, name_ref_i, merge_cp_p, 291 merge_cp_length_p, THREAD); 292 293 int signature_ref_i = scratch_cp->signature_ref_index_at(scratch_i); 294 int new_signature_ref_i = find_or_append_indirect_entry(scratch_cp, signature_ref_i, 295 merge_cp_p, merge_cp_length_p, 296 THREAD); 297 298 // If the referenced entries already exist in *merge_cp_p, then 299 // both new_name_ref_i and new_signature_ref_i will both be 0. 300 // In that case, all we are appending is the current entry. 301 if (new_name_ref_i != name_ref_i) { 302 RC_TRACE(0x00080000, 303 ("NameAndType entry@%d name_ref_index change: %d to %d", 304 *merge_cp_length_p, name_ref_i, new_name_ref_i)); 305 } 306 if (new_signature_ref_i != signature_ref_i) { 307 RC_TRACE(0x00080000, 308 ("NameAndType entry@%d signature_ref_index change: %d to %d", 309 *merge_cp_length_p, signature_ref_i, new_signature_ref_i)); 310 } 311 312 (*merge_cp_p)->name_and_type_at_put(*merge_cp_length_p, 313 new_name_ref_i, new_signature_ref_i); 314 if (scratch_i != *merge_cp_length_p) { 315 // The new entry in *merge_cp_p is at a different index than 316 // the new entry in scratch_cp so we need to map the index values. 317 map_index(scratch_cp, scratch_i, *merge_cp_length_p); 318 } 319 (*merge_cp_length_p)++; 320 } break; 321 322 // this is a double-indirect CP entry so it needs special handling 323 case JVM_CONSTANT_Fieldref: // fall through 324 case JVM_CONSTANT_InterfaceMethodref: // fall through 325 case JVM_CONSTANT_Methodref: 326 { 327 int klass_ref_i = scratch_cp->uncached_klass_ref_index_at(scratch_i); 328 int new_klass_ref_i = find_or_append_indirect_entry(scratch_cp, klass_ref_i, 329 merge_cp_p, merge_cp_length_p, THREAD); 330 331 int name_and_type_ref_i = scratch_cp->uncached_name_and_type_ref_index_at(scratch_i); 332 int new_name_and_type_ref_i = find_or_append_indirect_entry(scratch_cp, name_and_type_ref_i, 333 merge_cp_p, merge_cp_length_p, THREAD); 334 335 const char *entry_name; 336 switch (scratch_cp->tag_at(scratch_i).value()) { 337 case JVM_CONSTANT_Fieldref: 338 entry_name = "Fieldref"; 339 (*merge_cp_p)->field_at_put(*merge_cp_length_p, new_klass_ref_i, 340 new_name_and_type_ref_i); 341 break; 342 case JVM_CONSTANT_InterfaceMethodref: 343 entry_name = "IFMethodref"; 344 (*merge_cp_p)->interface_method_at_put(*merge_cp_length_p, 345 new_klass_ref_i, new_name_and_type_ref_i); 346 break; 347 case JVM_CONSTANT_Methodref: 348 entry_name = "Methodref"; 349 (*merge_cp_p)->method_at_put(*merge_cp_length_p, new_klass_ref_i, 350 new_name_and_type_ref_i); 351 break; 352 default: 353 guarantee(false, "bad switch"); 354 break; 355 } 356 357 if (klass_ref_i != new_klass_ref_i) { 358 RC_TRACE(0x00080000, ("%s entry@%d class_index changed: %d to %d", 359 entry_name, *merge_cp_length_p, klass_ref_i, new_klass_ref_i)); 360 } 361 if (name_and_type_ref_i != new_name_and_type_ref_i) { 362 RC_TRACE(0x00080000, 363 ("%s entry@%d name_and_type_index changed: %d to %d", 364 entry_name, *merge_cp_length_p, name_and_type_ref_i, 365 new_name_and_type_ref_i)); 366 } 367 368 if (scratch_i != *merge_cp_length_p) { 369 // The new entry in *merge_cp_p is at a different index than 370 // the new entry in scratch_cp so we need to map the index values. 371 map_index(scratch_cp, scratch_i, *merge_cp_length_p); 372 } 373 (*merge_cp_length_p)++; 374 } break; 375 376 // this is an indirect CP entry so it needs special handling 377 case JVM_CONSTANT_MethodType: 378 { 379 int ref_i = scratch_cp->method_type_index_at(scratch_i); 380 int new_ref_i = find_or_append_indirect_entry(scratch_cp, ref_i, merge_cp_p, 381 merge_cp_length_p, THREAD); 382 if (new_ref_i != ref_i) { 383 RC_TRACE(0x00080000, 384 ("MethodType entry@%d ref_index change: %d to %d", 385 *merge_cp_length_p, ref_i, new_ref_i)); 386 } 387 (*merge_cp_p)->method_type_index_at_put(*merge_cp_length_p, new_ref_i); 388 if (scratch_i != *merge_cp_length_p) { 389 // The new entry in *merge_cp_p is at a different index than 390 // the new entry in scratch_cp so we need to map the index values. 391 map_index(scratch_cp, scratch_i, *merge_cp_length_p); 392 } 393 (*merge_cp_length_p)++; 394 } break; 395 396 // this is an indirect CP entry so it needs special handling 397 case JVM_CONSTANT_MethodHandle: 398 { 399 int ref_kind = scratch_cp->method_handle_ref_kind_at(scratch_i); 400 int ref_i = scratch_cp->method_handle_index_at(scratch_i); 401 int new_ref_i = find_or_append_indirect_entry(scratch_cp, ref_i, merge_cp_p, 402 merge_cp_length_p, THREAD); 403 if (new_ref_i != ref_i) { 404 RC_TRACE(0x00080000, 405 ("MethodHandle entry@%d ref_index change: %d to %d", 406 *merge_cp_length_p, ref_i, new_ref_i)); 407 } 408 (*merge_cp_p)->method_handle_index_at_put(*merge_cp_length_p, ref_kind, new_ref_i); 409 if (scratch_i != *merge_cp_length_p) { 410 // The new entry in *merge_cp_p is at a different index than 411 // the new entry in scratch_cp so we need to map the index values. 412 map_index(scratch_cp, scratch_i, *merge_cp_length_p); 413 } 414 (*merge_cp_length_p)++; 415 } break; 416 417 // this is an indirect CP entry so it needs special handling 418 case JVM_CONSTANT_InvokeDynamic: 419 { 420 // Index of the bootstrap specifier in the operands array 421 int old_bs_i = scratch_cp->invoke_dynamic_bootstrap_specifier_index(scratch_i); 422 int new_bs_i = find_or_append_operand(scratch_cp, old_bs_i, merge_cp_p, 423 merge_cp_length_p, THREAD); 424 // The bootstrap method NameAndType_info index 425 int old_ref_i = scratch_cp->invoke_dynamic_name_and_type_ref_index_at(scratch_i); 426 int new_ref_i = find_or_append_indirect_entry(scratch_cp, old_ref_i, merge_cp_p, 427 merge_cp_length_p, THREAD); 428 if (new_bs_i != old_bs_i) { 429 RC_TRACE(0x00080000, 430 ("InvokeDynamic entry@%d bootstrap_method_attr_index change: %d to %d", 431 *merge_cp_length_p, old_bs_i, new_bs_i)); 432 } 433 if (new_ref_i != old_ref_i) { 434 RC_TRACE(0x00080000, 435 ("InvokeDynamic entry@%d name_and_type_index change: %d to %d", 436 *merge_cp_length_p, old_ref_i, new_ref_i)); 437 } 438 439 (*merge_cp_p)->invoke_dynamic_at_put(*merge_cp_length_p, new_bs_i, new_ref_i); 440 if (scratch_i != *merge_cp_length_p) { 441 // The new entry in *merge_cp_p is at a different index than 442 // the new entry in scratch_cp so we need to map the index values. 443 map_index(scratch_cp, scratch_i, *merge_cp_length_p); 444 } 445 (*merge_cp_length_p)++; 446 } break; 447 448 // At this stage, Class or UnresolvedClass could be here, but not 449 // ClassIndex 450 case JVM_CONSTANT_ClassIndex: // fall through 451 452 // Invalid is used as the tag for the second constant pool entry 453 // occupied by JVM_CONSTANT_Double or JVM_CONSTANT_Long. It should 454 // not be seen by itself. 455 case JVM_CONSTANT_Invalid: // fall through 456 457 // At this stage, String could be here, but not StringIndex 458 case JVM_CONSTANT_StringIndex: // fall through 459 460 // At this stage JVM_CONSTANT_UnresolvedClassInError should not be 461 // here 462 case JVM_CONSTANT_UnresolvedClassInError: // fall through 463 464 default: 465 { 466 // leave a breadcrumb 467 jbyte bad_value = scratch_cp->tag_at(scratch_i).value(); 468 ShouldNotReachHere(); 469 } break; 470 } // end switch tag value 471 } // end append_entry() 472 473 474 int VM_RedefineClasses::find_or_append_indirect_entry(constantPoolHandle scratch_cp, 475 int ref_i, constantPoolHandle *merge_cp_p, int *merge_cp_length_p, TRAPS) { 476 477 int new_ref_i = ref_i; 478 bool match = (ref_i < *merge_cp_length_p) && 479 scratch_cp->compare_entry_to(ref_i, *merge_cp_p, ref_i, THREAD); 480 481 if (!match) { 482 // forward reference in *merge_cp_p or not a direct match 483 int found_i = scratch_cp->find_matching_entry(ref_i, *merge_cp_p, THREAD); 484 if (found_i != 0) { 485 guarantee(found_i != ref_i, "compare_entry_to() and find_matching_entry() do not agree"); 486 // Found a matching entry somewhere else in *merge_cp_p so just need a mapping entry. 487 new_ref_i = found_i; 488 map_index(scratch_cp, ref_i, found_i); 489 } else { 490 // no match found so we have to append this entry to *merge_cp_p 491 append_entry(scratch_cp, ref_i, merge_cp_p, merge_cp_length_p, THREAD); 492 // The above call to append_entry() can only append one entry 493 // so the post call query of *merge_cp_length_p is only for 494 // the sake of consistency. 495 new_ref_i = *merge_cp_length_p - 1; 496 } 497 } 498 499 return new_ref_i; 500 } // end find_or_append_indirect_entry() 501 502 503 // Append a bootstrap specifier into the merge_cp operands that is semantically equal 504 // to the scratch_cp operands bootstrap specifier passed by the old_bs_i index. 505 // Recursively append new merge_cp entries referenced by the new bootstrap specifier. 506 void VM_RedefineClasses::append_operand(constantPoolHandle scratch_cp, int old_bs_i, 507 constantPoolHandle *merge_cp_p, int *merge_cp_length_p, TRAPS) { 508 509 int old_ref_i = scratch_cp->operand_bootstrap_method_ref_index_at(old_bs_i); 510 int new_ref_i = find_or_append_indirect_entry(scratch_cp, old_ref_i, merge_cp_p, 511 merge_cp_length_p, THREAD); 512 if (new_ref_i != old_ref_i) { 513 RC_TRACE(0x00080000, 514 ("operands entry@%d bootstrap method ref_index change: %d to %d", 515 _operands_cur_length, old_ref_i, new_ref_i)); 516 } 517 518 Array<u2>* merge_ops = (*merge_cp_p)->operands(); 519 int new_bs_i = _operands_cur_length; 520 // We have _operands_cur_length == 0 when the merge_cp operands is empty yet. 521 // However, the operand_offset_at(0) was set in the extend_operands() call. 522 int new_base = (new_bs_i == 0) ? (*merge_cp_p)->operand_offset_at(0) 523 : (*merge_cp_p)->operand_next_offset_at(new_bs_i - 1); 524 int argc = scratch_cp->operand_argument_count_at(old_bs_i); 525 526 ConstantPool::operand_offset_at_put(merge_ops, _operands_cur_length, new_base); 527 merge_ops->at_put(new_base++, new_ref_i); 528 merge_ops->at_put(new_base++, argc); 529 530 for (int i = 0; i < argc; i++) { 531 int old_arg_ref_i = scratch_cp->operand_argument_index_at(old_bs_i, i); 532 int new_arg_ref_i = find_or_append_indirect_entry(scratch_cp, old_arg_ref_i, merge_cp_p, 533 merge_cp_length_p, THREAD); 534 merge_ops->at_put(new_base++, new_arg_ref_i); 535 if (new_arg_ref_i != old_arg_ref_i) { 536 RC_TRACE(0x00080000, 537 ("operands entry@%d bootstrap method argument ref_index change: %d to %d", 538 _operands_cur_length, old_arg_ref_i, new_arg_ref_i)); 539 } 540 } 541 if (old_bs_i != _operands_cur_length) { 542 // The bootstrap specifier in *merge_cp_p is at a different index than 543 // that in scratch_cp so we need to map the index values. 544 map_operand_index(old_bs_i, new_bs_i); 545 } 546 _operands_cur_length++; 547 } // end append_operand() 548 549 550 int VM_RedefineClasses::find_or_append_operand(constantPoolHandle scratch_cp, 551 int old_bs_i, constantPoolHandle *merge_cp_p, int *merge_cp_length_p, TRAPS) { 552 553 int new_bs_i = old_bs_i; // bootstrap specifier index 554 bool match = (old_bs_i < _operands_cur_length) && 555 scratch_cp->compare_operand_to(old_bs_i, *merge_cp_p, old_bs_i, THREAD); 556 557 if (!match) { 558 // forward reference in *merge_cp_p or not a direct match 559 int found_i = scratch_cp->find_matching_operand(old_bs_i, *merge_cp_p, 560 _operands_cur_length, THREAD); 561 if (found_i != -1) { 562 guarantee(found_i != old_bs_i, "compare_operand_to() and find_matching_operand() disagree"); 563 // found a matching operand somewhere else in *merge_cp_p so just need a mapping 564 new_bs_i = found_i; 565 map_operand_index(old_bs_i, found_i); 566 } else { 567 // no match found so we have to append this bootstrap specifier to *merge_cp_p 568 append_operand(scratch_cp, old_bs_i, merge_cp_p, merge_cp_length_p, THREAD); 569 new_bs_i = _operands_cur_length - 1; 570 } 571 } 572 return new_bs_i; 573 } // end find_or_append_operand() 574 575 576 void VM_RedefineClasses::finalize_operands_merge(constantPoolHandle merge_cp, TRAPS) { 577 if (merge_cp->operands() == NULL) { 578 return; 579 } 580 // Shrink the merge_cp operands 581 merge_cp->shrink_operands(_operands_cur_length, CHECK); 582 583 if (RC_TRACE_ENABLED(0x00040000)) { 584 // don't want to loop unless we are tracing 585 int count = 0; 586 for (int i = 1; i < _operands_index_map_p->length(); i++) { 587 int value = _operands_index_map_p->at(i); 588 if (value != -1) { 589 RC_TRACE_WITH_THREAD(0x00040000, THREAD, 590 ("operands_index_map[%d]: old=%d new=%d", count, i, value)); 591 count++; 592 } 593 } 594 } 595 // Clean-up 596 _operands_index_map_p = NULL; 597 _operands_cur_length = 0; 598 _operands_index_map_count = 0; 599 } // end finalize_operands_merge() 600 601 602 jvmtiError VM_RedefineClasses::compare_and_normalize_class_versions( 603 instanceKlassHandle the_class, 604 instanceKlassHandle scratch_class) { 605 int i; 606 607 // Check superclasses, or rather their names, since superclasses themselves can be 608 // requested to replace. 609 // Check for NULL superclass first since this might be java.lang.Object 610 if (the_class->super() != scratch_class->super() && 611 (the_class->super() == NULL || scratch_class->super() == NULL || 612 the_class->super()->name() != 613 scratch_class->super()->name())) { 614 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_HIERARCHY_CHANGED; 615 } 616 617 // Check if the number, names and order of directly implemented interfaces are the same. 618 // I think in principle we should just check if the sets of names of directly implemented 619 // interfaces are the same, i.e. the order of declaration (which, however, if changed in the 620 // .java file, also changes in .class file) should not matter. However, comparing sets is 621 // technically a bit more difficult, and, more importantly, I am not sure at present that the 622 // order of interfaces does not matter on the implementation level, i.e. that the VM does not 623 // rely on it somewhere. 624 Array<Klass*>* k_interfaces = the_class->local_interfaces(); 625 Array<Klass*>* k_new_interfaces = scratch_class->local_interfaces(); 626 int n_intfs = k_interfaces->length(); 627 if (n_intfs != k_new_interfaces->length()) { 628 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_HIERARCHY_CHANGED; 629 } 630 for (i = 0; i < n_intfs; i++) { 631 if (k_interfaces->at(i)->name() != 632 k_new_interfaces->at(i)->name()) { 633 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_HIERARCHY_CHANGED; 634 } 635 } 636 637 // Check whether class is in the error init state. 638 if (the_class->is_in_error_state()) { 639 // TBD #5057930: special error code is needed in 1.6 640 return JVMTI_ERROR_INVALID_CLASS; 641 } 642 643 // Check whether class modifiers are the same. 644 jushort old_flags = (jushort) the_class->access_flags().get_flags(); 645 jushort new_flags = (jushort) scratch_class->access_flags().get_flags(); 646 if (old_flags != new_flags) { 647 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_CLASS_MODIFIERS_CHANGED; 648 } 649 650 // Check if the number, names, types and order of fields declared in these classes 651 // are the same. 652 JavaFieldStream old_fs(the_class); 653 JavaFieldStream new_fs(scratch_class); 654 for (; !old_fs.done() && !new_fs.done(); old_fs.next(), new_fs.next()) { 655 // access 656 old_flags = old_fs.access_flags().as_short(); 657 new_flags = new_fs.access_flags().as_short(); 658 if ((old_flags ^ new_flags) & JVM_RECOGNIZED_FIELD_MODIFIERS) { 659 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_SCHEMA_CHANGED; 660 } 661 // offset 662 if (old_fs.offset() != new_fs.offset()) { 663 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_SCHEMA_CHANGED; 664 } 665 // name and signature 666 Symbol* name_sym1 = the_class->constants()->symbol_at(old_fs.name_index()); 667 Symbol* sig_sym1 = the_class->constants()->symbol_at(old_fs.signature_index()); 668 Symbol* name_sym2 = scratch_class->constants()->symbol_at(new_fs.name_index()); 669 Symbol* sig_sym2 = scratch_class->constants()->symbol_at(new_fs.signature_index()); 670 if (name_sym1 != name_sym2 || sig_sym1 != sig_sym2) { 671 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_SCHEMA_CHANGED; 672 } 673 } 674 675 // If both streams aren't done then we have a differing number of 676 // fields. 677 if (!old_fs.done() || !new_fs.done()) { 678 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_SCHEMA_CHANGED; 679 } 680 681 // Do a parallel walk through the old and new methods. Detect 682 // cases where they match (exist in both), have been added in 683 // the new methods, or have been deleted (exist only in the 684 // old methods). The class file parser places methods in order 685 // by method name, but does not order overloaded methods by 686 // signature. In order to determine what fate befell the methods, 687 // this code places the overloaded new methods that have matching 688 // old methods in the same order as the old methods and places 689 // new overloaded methods at the end of overloaded methods of 690 // that name. The code for this order normalization is adapted 691 // from the algorithm used in InstanceKlass::find_method(). 692 // Since we are swapping out of order entries as we find them, 693 // we only have to search forward through the overloaded methods. 694 // Methods which are added and have the same name as an existing 695 // method (but different signature) will be put at the end of 696 // the methods with that name, and the name mismatch code will 697 // handle them. 698 Array<Method*>* k_old_methods(the_class->methods()); 699 Array<Method*>* k_new_methods(scratch_class->methods()); 700 int n_old_methods = k_old_methods->length(); 701 int n_new_methods = k_new_methods->length(); 702 Thread* thread = Thread::current(); 703 704 int ni = 0; 705 int oi = 0; 706 while (true) { 707 Method* k_old_method; 708 Method* k_new_method; 709 enum { matched, added, deleted, undetermined } method_was = undetermined; 710 711 if (oi >= n_old_methods) { 712 if (ni >= n_new_methods) { 713 break; // we've looked at everything, done 714 } 715 // New method at the end 716 k_new_method = k_new_methods->at(ni); 717 method_was = added; 718 } else if (ni >= n_new_methods) { 719 // Old method, at the end, is deleted 720 k_old_method = k_old_methods->at(oi); 721 method_was = deleted; 722 } else { 723 // There are more methods in both the old and new lists 724 k_old_method = k_old_methods->at(oi); 725 k_new_method = k_new_methods->at(ni); 726 if (k_old_method->name() != k_new_method->name()) { 727 // Methods are sorted by method name, so a mismatch means added 728 // or deleted 729 if (k_old_method->name()->fast_compare(k_new_method->name()) > 0) { 730 method_was = added; 731 } else { 732 method_was = deleted; 733 } 734 } else if (k_old_method->signature() == k_new_method->signature()) { 735 // Both the name and signature match 736 method_was = matched; 737 } else { 738 // The name matches, but the signature doesn't, which means we have to 739 // search forward through the new overloaded methods. 740 int nj; // outside the loop for post-loop check 741 for (nj = ni + 1; nj < n_new_methods; nj++) { 742 Method* m = k_new_methods->at(nj); 743 if (k_old_method->name() != m->name()) { 744 // reached another method name so no more overloaded methods 745 method_was = deleted; 746 break; 747 } 748 if (k_old_method->signature() == m->signature()) { 749 // found a match so swap the methods 750 k_new_methods->at_put(ni, m); 751 k_new_methods->at_put(nj, k_new_method); 752 k_new_method = m; 753 method_was = matched; 754 break; 755 } 756 } 757 758 if (nj >= n_new_methods) { 759 // reached the end without a match; so method was deleted 760 method_was = deleted; 761 } 762 } 763 } 764 765 switch (method_was) { 766 case matched: 767 // methods match, be sure modifiers do too 768 old_flags = (jushort) k_old_method->access_flags().get_flags(); 769 new_flags = (jushort) k_new_method->access_flags().get_flags(); 770 if ((old_flags ^ new_flags) & ~(JVM_ACC_NATIVE)) { 771 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_METHOD_MODIFIERS_CHANGED; 772 } 773 { 774 u2 new_num = k_new_method->method_idnum(); 775 u2 old_num = k_old_method->method_idnum(); 776 if (new_num != old_num) { 777 Method* idnum_owner = scratch_class->method_with_idnum(old_num); 778 if (idnum_owner != NULL) { 779 // There is already a method assigned this idnum -- switch them 780 idnum_owner->set_method_idnum(new_num); 781 } 782 k_new_method->set_method_idnum(old_num); 783 if (thread->has_pending_exception()) { 784 return JVMTI_ERROR_OUT_OF_MEMORY; 785 } 786 } 787 } 788 RC_TRACE(0x00008000, ("Method matched: new: %s [%d] == old: %s [%d]", 789 k_new_method->name_and_sig_as_C_string(), ni, 790 k_old_method->name_and_sig_as_C_string(), oi)); 791 // advance to next pair of methods 792 ++oi; 793 ++ni; 794 break; 795 case added: 796 // method added, see if it is OK 797 new_flags = (jushort) k_new_method->access_flags().get_flags(); 798 if ((new_flags & JVM_ACC_PRIVATE) == 0 799 // hack: private should be treated as final, but alas 800 || (new_flags & (JVM_ACC_FINAL|JVM_ACC_STATIC)) == 0 801 ) { 802 // new methods must be private 803 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_METHOD_ADDED; 804 } 805 { 806 u2 num = the_class->next_method_idnum(); 807 if (num == ConstMethod::UNSET_IDNUM) { 808 // cannot add any more methods 809 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_METHOD_ADDED; 810 } 811 u2 new_num = k_new_method->method_idnum(); 812 Method* idnum_owner = scratch_class->method_with_idnum(num); 813 if (idnum_owner != NULL) { 814 // There is already a method assigned this idnum -- switch them 815 idnum_owner->set_method_idnum(new_num); 816 } 817 k_new_method->set_method_idnum(num); 818 if (thread->has_pending_exception()) { 819 return JVMTI_ERROR_OUT_OF_MEMORY; 820 } 821 } 822 RC_TRACE(0x00008000, ("Method added: new: %s [%d]", 823 k_new_method->name_and_sig_as_C_string(), ni)); 824 ++ni; // advance to next new method 825 break; 826 case deleted: 827 // method deleted, see if it is OK 828 old_flags = (jushort) k_old_method->access_flags().get_flags(); 829 if ((old_flags & JVM_ACC_PRIVATE) == 0 830 // hack: private should be treated as final, but alas 831 || (old_flags & (JVM_ACC_FINAL|JVM_ACC_STATIC)) == 0 832 ) { 833 // deleted methods must be private 834 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_METHOD_DELETED; 835 } 836 RC_TRACE(0x00008000, ("Method deleted: old: %s [%d]", 837 k_old_method->name_and_sig_as_C_string(), oi)); 838 ++oi; // advance to next old method 839 break; 840 default: 841 ShouldNotReachHere(); 842 } 843 } 844 845 return JVMTI_ERROR_NONE; 846 } 847 848 849 // Find new constant pool index value for old constant pool index value 850 // by seaching the index map. Returns zero (0) if there is no mapped 851 // value for the old constant pool index. 852 int VM_RedefineClasses::find_new_index(int old_index) { 853 if (_index_map_count == 0) { 854 // map is empty so nothing can be found 855 return 0; 856 } 857 858 if (old_index < 1 || old_index >= _index_map_p->length()) { 859 // The old_index is out of range so it is not mapped. This should 860 // not happen in regular constant pool merging use, but it can 861 // happen if a corrupt annotation is processed. 862 return 0; 863 } 864 865 int value = _index_map_p->at(old_index); 866 if (value == -1) { 867 // the old_index is not mapped 868 return 0; 869 } 870 871 return value; 872 } // end find_new_index() 873 874 875 // Find new bootstrap specifier index value for old bootstrap specifier index 876 // value by seaching the index map. Returns unused index (-1) if there is 877 // no mapped value for the old bootstrap specifier index. 878 int VM_RedefineClasses::find_new_operand_index(int old_index) { 879 if (_operands_index_map_count == 0) { 880 // map is empty so nothing can be found 881 return -1; 882 } 883 884 if (old_index == -1 || old_index >= _operands_index_map_p->length()) { 885 // The old_index is out of range so it is not mapped. 886 // This should not happen in regular constant pool merging use. 887 return -1; 888 } 889 890 int value = _operands_index_map_p->at(old_index); 891 if (value == -1) { 892 // the old_index is not mapped 893 return -1; 894 } 895 896 return value; 897 } // end find_new_operand_index() 898 899 900 // Returns true if the current mismatch is due to a resolved/unresolved 901 // class pair. Otherwise, returns false. 902 bool VM_RedefineClasses::is_unresolved_class_mismatch(constantPoolHandle cp1, 903 int index1, constantPoolHandle cp2, int index2) { 904 905 jbyte t1 = cp1->tag_at(index1).value(); 906 if (t1 != JVM_CONSTANT_Class && t1 != JVM_CONSTANT_UnresolvedClass) { 907 return false; // wrong entry type; not our special case 908 } 909 910 jbyte t2 = cp2->tag_at(index2).value(); 911 if (t2 != JVM_CONSTANT_Class && t2 != JVM_CONSTANT_UnresolvedClass) { 912 return false; // wrong entry type; not our special case 913 } 914 915 if (t1 == t2) { 916 return false; // not a mismatch; not our special case 917 } 918 919 char *s1 = cp1->klass_name_at(index1)->as_C_string(); 920 char *s2 = cp2->klass_name_at(index2)->as_C_string(); 921 if (strcmp(s1, s2) != 0) { 922 return false; // strings don't match; not our special case 923 } 924 925 return true; // made it through the gauntlet; this is our special case 926 } // end is_unresolved_class_mismatch() 927 928 929 jvmtiError VM_RedefineClasses::load_new_class_versions(TRAPS) { 930 931 // For consistency allocate memory using os::malloc wrapper. 932 _scratch_classes = (Klass**) 933 os::malloc(sizeof(Klass*) * _class_count, mtClass); 934 if (_scratch_classes == NULL) { 935 return JVMTI_ERROR_OUT_OF_MEMORY; 936 } 937 // Zero initialize the _scratch_classes array. 938 for (int i = 0; i < _class_count; i++) { 939 _scratch_classes[i] = NULL; 940 } 941 942 ResourceMark rm(THREAD); 943 944 JvmtiThreadState *state = JvmtiThreadState::state_for(JavaThread::current()); 945 // state can only be NULL if the current thread is exiting which 946 // should not happen since we're trying to do a RedefineClasses 947 guarantee(state != NULL, "exiting thread calling load_new_class_versions"); 948 for (int i = 0; i < _class_count; i++) { 949 // Create HandleMark so that any handles created while loading new class 950 // versions are deleted. Constant pools are deallocated while merging 951 // constant pools 952 HandleMark hm(THREAD); 953 954 oop mirror = JNIHandles::resolve_non_null(_class_defs[i].klass); 955 // classes for primitives cannot be redefined 956 if (!is_modifiable_class(mirror)) { 957 return JVMTI_ERROR_UNMODIFIABLE_CLASS; 958 } 959 Klass* the_class_oop = java_lang_Class::as_Klass(mirror); 960 instanceKlassHandle the_class = instanceKlassHandle(THREAD, the_class_oop); 961 Symbol* the_class_sym = the_class->name(); 962 963 // RC_TRACE_WITH_THREAD macro has an embedded ResourceMark 964 RC_TRACE_WITH_THREAD(0x00000001, THREAD, 965 ("loading name=%s kind=%d (avail_mem=" UINT64_FORMAT "K)", 966 the_class->external_name(), _class_load_kind, 967 os::available_memory() >> 10)); 968 969 ClassFileStream st((u1*) _class_defs[i].class_bytes, 970 _class_defs[i].class_byte_count, (char *)"__VM_RedefineClasses__"); 971 972 // Parse the stream. 973 Handle the_class_loader(THREAD, the_class->class_loader()); 974 Handle protection_domain(THREAD, the_class->protection_domain()); 975 // Set redefined class handle in JvmtiThreadState class. 976 // This redefined class is sent to agent event handler for class file 977 // load hook event. 978 state->set_class_being_redefined(&the_class, _class_load_kind); 979 980 Klass* k = SystemDictionary::parse_stream(the_class_sym, 981 the_class_loader, 982 protection_domain, 983 &st, 984 THREAD); 985 // Clear class_being_redefined just to be sure. 986 state->clear_class_being_redefined(); 987 988 // TODO: if this is retransform, and nothing changed we can skip it 989 990 instanceKlassHandle scratch_class (THREAD, k); 991 992 // Need to clean up allocated InstanceKlass if there's an error so assign 993 // the result here. Caller deallocates all the scratch classes in case of 994 // an error. 995 _scratch_classes[i] = k; 996 997 if (HAS_PENDING_EXCEPTION) { 998 Symbol* ex_name = PENDING_EXCEPTION->klass()->name(); 999 // RC_TRACE_WITH_THREAD macro has an embedded ResourceMark 1000 RC_TRACE_WITH_THREAD(0x00000002, THREAD, ("parse_stream exception: '%s'", 1001 ex_name->as_C_string())); 1002 CLEAR_PENDING_EXCEPTION; 1003 1004 if (ex_name == vmSymbols::java_lang_UnsupportedClassVersionError()) { 1005 return JVMTI_ERROR_UNSUPPORTED_VERSION; 1006 } else if (ex_name == vmSymbols::java_lang_ClassFormatError()) { 1007 return JVMTI_ERROR_INVALID_CLASS_FORMAT; 1008 } else if (ex_name == vmSymbols::java_lang_ClassCircularityError()) { 1009 return JVMTI_ERROR_CIRCULAR_CLASS_DEFINITION; 1010 } else if (ex_name == vmSymbols::java_lang_NoClassDefFoundError()) { 1011 // The message will be "XXX (wrong name: YYY)" 1012 return JVMTI_ERROR_NAMES_DONT_MATCH; 1013 } else if (ex_name == vmSymbols::java_lang_OutOfMemoryError()) { 1014 return JVMTI_ERROR_OUT_OF_MEMORY; 1015 } else { // Just in case more exceptions can be thrown.. 1016 return JVMTI_ERROR_FAILS_VERIFICATION; 1017 } 1018 } 1019 1020 // Ensure class is linked before redefine 1021 if (!the_class->is_linked()) { 1022 the_class->link_class(THREAD); 1023 if (HAS_PENDING_EXCEPTION) { 1024 Symbol* ex_name = PENDING_EXCEPTION->klass()->name(); 1025 // RC_TRACE_WITH_THREAD macro has an embedded ResourceMark 1026 RC_TRACE_WITH_THREAD(0x00000002, THREAD, ("link_class exception: '%s'", 1027 ex_name->as_C_string())); 1028 CLEAR_PENDING_EXCEPTION; 1029 if (ex_name == vmSymbols::java_lang_OutOfMemoryError()) { 1030 return JVMTI_ERROR_OUT_OF_MEMORY; 1031 } else { 1032 return JVMTI_ERROR_INTERNAL; 1033 } 1034 } 1035 } 1036 1037 // Do the validity checks in compare_and_normalize_class_versions() 1038 // before verifying the byte codes. By doing these checks first, we 1039 // limit the number of functions that require redirection from 1040 // the_class to scratch_class. In particular, we don't have to 1041 // modify JNI GetSuperclass() and thus won't change its performance. 1042 jvmtiError res = compare_and_normalize_class_versions(the_class, 1043 scratch_class); 1044 if (res != JVMTI_ERROR_NONE) { 1045 return res; 1046 } 1047 1048 // verify what the caller passed us 1049 { 1050 // The bug 6214132 caused the verification to fail. 1051 // Information about the_class and scratch_class is temporarily 1052 // recorded into jvmtiThreadState. This data is used to redirect 1053 // the_class to scratch_class in the JVM_* functions called by the 1054 // verifier. Please, refer to jvmtiThreadState.hpp for the detailed 1055 // description. 1056 RedefineVerifyMark rvm(&the_class, &scratch_class, state); 1057 Verifier::verify( 1058 scratch_class, Verifier::ThrowException, true, THREAD); 1059 } 1060 1061 if (HAS_PENDING_EXCEPTION) { 1062 Symbol* ex_name = PENDING_EXCEPTION->klass()->name(); 1063 // RC_TRACE_WITH_THREAD macro has an embedded ResourceMark 1064 RC_TRACE_WITH_THREAD(0x00000002, THREAD, 1065 ("verify_byte_codes exception: '%s'", ex_name->as_C_string())); 1066 CLEAR_PENDING_EXCEPTION; 1067 if (ex_name == vmSymbols::java_lang_OutOfMemoryError()) { 1068 return JVMTI_ERROR_OUT_OF_MEMORY; 1069 } else { 1070 // tell the caller the bytecodes are bad 1071 return JVMTI_ERROR_FAILS_VERIFICATION; 1072 } 1073 } 1074 1075 res = merge_cp_and_rewrite(the_class, scratch_class, THREAD); 1076 if (HAS_PENDING_EXCEPTION) { 1077 Symbol* ex_name = PENDING_EXCEPTION->klass()->name(); 1078 // RC_TRACE_WITH_THREAD macro has an embedded ResourceMark 1079 RC_TRACE_WITH_THREAD(0x00000002, THREAD, 1080 ("merge_cp_and_rewrite exception: '%s'", ex_name->as_C_string())); 1081 CLEAR_PENDING_EXCEPTION; 1082 if (ex_name == vmSymbols::java_lang_OutOfMemoryError()) { 1083 return JVMTI_ERROR_OUT_OF_MEMORY; 1084 } else { 1085 return JVMTI_ERROR_INTERNAL; 1086 } 1087 } 1088 1089 if (VerifyMergedCPBytecodes) { 1090 // verify what we have done during constant pool merging 1091 { 1092 RedefineVerifyMark rvm(&the_class, &scratch_class, state); 1093 Verifier::verify(scratch_class, Verifier::ThrowException, true, THREAD); 1094 } 1095 1096 if (HAS_PENDING_EXCEPTION) { 1097 Symbol* ex_name = PENDING_EXCEPTION->klass()->name(); 1098 // RC_TRACE_WITH_THREAD macro has an embedded ResourceMark 1099 RC_TRACE_WITH_THREAD(0x00000002, THREAD, 1100 ("verify_byte_codes post merge-CP exception: '%s'", 1101 ex_name->as_C_string())); 1102 CLEAR_PENDING_EXCEPTION; 1103 if (ex_name == vmSymbols::java_lang_OutOfMemoryError()) { 1104 return JVMTI_ERROR_OUT_OF_MEMORY; 1105 } else { 1106 // tell the caller that constant pool merging screwed up 1107 return JVMTI_ERROR_INTERNAL; 1108 } 1109 } 1110 } 1111 1112 Rewriter::rewrite(scratch_class, THREAD); 1113 if (!HAS_PENDING_EXCEPTION) { 1114 scratch_class->link_methods(THREAD); 1115 } 1116 if (HAS_PENDING_EXCEPTION) { 1117 Symbol* ex_name = PENDING_EXCEPTION->klass()->name(); 1118 // RC_TRACE_WITH_THREAD macro has an embedded ResourceMark 1119 RC_TRACE_WITH_THREAD(0x00000002, THREAD, 1120 ("Rewriter::rewrite or link_methods exception: '%s'", ex_name->as_C_string())); 1121 CLEAR_PENDING_EXCEPTION; 1122 if (ex_name == vmSymbols::java_lang_OutOfMemoryError()) { 1123 return JVMTI_ERROR_OUT_OF_MEMORY; 1124 } else { 1125 return JVMTI_ERROR_INTERNAL; 1126 } 1127 } 1128 1129 // RC_TRACE_WITH_THREAD macro has an embedded ResourceMark 1130 RC_TRACE_WITH_THREAD(0x00000001, THREAD, 1131 ("loaded name=%s (avail_mem=" UINT64_FORMAT "K)", 1132 the_class->external_name(), os::available_memory() >> 10)); 1133 } 1134 1135 return JVMTI_ERROR_NONE; 1136 } 1137 1138 1139 // Map old_index to new_index as needed. scratch_cp is only needed 1140 // for RC_TRACE() calls. 1141 void VM_RedefineClasses::map_index(constantPoolHandle scratch_cp, 1142 int old_index, int new_index) { 1143 if (find_new_index(old_index) != 0) { 1144 // old_index is already mapped 1145 return; 1146 } 1147 1148 if (old_index == new_index) { 1149 // no mapping is needed 1150 return; 1151 } 1152 1153 _index_map_p->at_put(old_index, new_index); 1154 _index_map_count++; 1155 1156 RC_TRACE(0x00040000, ("mapped tag %d at index %d to %d", 1157 scratch_cp->tag_at(old_index).value(), old_index, new_index)); 1158 } // end map_index() 1159 1160 1161 // Map old_index to new_index as needed. 1162 void VM_RedefineClasses::map_operand_index(int old_index, int new_index) { 1163 if (find_new_operand_index(old_index) != -1) { 1164 // old_index is already mapped 1165 return; 1166 } 1167 1168 if (old_index == new_index) { 1169 // no mapping is needed 1170 return; 1171 } 1172 1173 _operands_index_map_p->at_put(old_index, new_index); 1174 _operands_index_map_count++; 1175 1176 RC_TRACE(0x00040000, ("mapped bootstrap specifier at index %d to %d", old_index, new_index)); 1177 } // end map_index() 1178 1179 1180 // Merge old_cp and scratch_cp and return the results of the merge via 1181 // merge_cp_p. The number of entries in *merge_cp_p is returned via 1182 // merge_cp_length_p. The entries in old_cp occupy the same locations 1183 // in *merge_cp_p. Also creates a map of indices from entries in 1184 // scratch_cp to the corresponding entry in *merge_cp_p. Index map 1185 // entries are only created for entries in scratch_cp that occupy a 1186 // different location in *merged_cp_p. 1187 bool VM_RedefineClasses::merge_constant_pools(constantPoolHandle old_cp, 1188 constantPoolHandle scratch_cp, constantPoolHandle *merge_cp_p, 1189 int *merge_cp_length_p, TRAPS) { 1190 1191 if (merge_cp_p == NULL) { 1192 assert(false, "caller must provide scratch constantPool"); 1193 return false; // robustness 1194 } 1195 if (merge_cp_length_p == NULL) { 1196 assert(false, "caller must provide scratch CP length"); 1197 return false; // robustness 1198 } 1199 // Worst case we need old_cp->length() + scratch_cp()->length(), 1200 // but the caller might be smart so make sure we have at least 1201 // the minimum. 1202 if ((*merge_cp_p)->length() < old_cp->length()) { 1203 assert(false, "merge area too small"); 1204 return false; // robustness 1205 } 1206 1207 RC_TRACE_WITH_THREAD(0x00010000, THREAD, 1208 ("old_cp_len=%d, scratch_cp_len=%d", old_cp->length(), 1209 scratch_cp->length())); 1210 1211 { 1212 // Pass 0: 1213 // The old_cp is copied to *merge_cp_p; this means that any code 1214 // using old_cp does not have to change. This work looks like a 1215 // perfect fit for ConstantPool*::copy_cp_to(), but we need to 1216 // handle one special case: 1217 // - revert JVM_CONSTANT_Class to JVM_CONSTANT_UnresolvedClass 1218 // This will make verification happy. 1219 1220 int old_i; // index into old_cp 1221 1222 // index zero (0) is not used in constantPools 1223 for (old_i = 1; old_i < old_cp->length(); old_i++) { 1224 // leave debugging crumb 1225 jbyte old_tag = old_cp->tag_at(old_i).value(); 1226 switch (old_tag) { 1227 case JVM_CONSTANT_Class: 1228 case JVM_CONSTANT_UnresolvedClass: 1229 // revert the copy to JVM_CONSTANT_UnresolvedClass 1230 // May be resolving while calling this so do the same for 1231 // JVM_CONSTANT_UnresolvedClass (klass_name_at() deals with transition) 1232 (*merge_cp_p)->unresolved_klass_at_put(old_i, 1233 old_cp->klass_name_at(old_i)); 1234 break; 1235 1236 case JVM_CONSTANT_Double: 1237 case JVM_CONSTANT_Long: 1238 // just copy the entry to *merge_cp_p, but double and long take 1239 // two constant pool entries 1240 ConstantPool::copy_entry_to(old_cp, old_i, *merge_cp_p, old_i, CHECK_0); 1241 old_i++; 1242 break; 1243 1244 default: 1245 // just copy the entry to *merge_cp_p 1246 ConstantPool::copy_entry_to(old_cp, old_i, *merge_cp_p, old_i, CHECK_0); 1247 break; 1248 } 1249 } // end for each old_cp entry 1250 1251 ConstantPool::copy_operands(old_cp, *merge_cp_p, CHECK_0); 1252 (*merge_cp_p)->extend_operands(scratch_cp, CHECK_0); 1253 1254 // We don't need to sanity check that *merge_cp_length_p is within 1255 // *merge_cp_p bounds since we have the minimum on-entry check above. 1256 (*merge_cp_length_p) = old_i; 1257 } 1258 1259 // merge_cp_len should be the same as old_cp->length() at this point 1260 // so this trace message is really a "warm-and-breathing" message. 1261 RC_TRACE_WITH_THREAD(0x00020000, THREAD, 1262 ("after pass 0: merge_cp_len=%d", *merge_cp_length_p)); 1263 1264 int scratch_i; // index into scratch_cp 1265 { 1266 // Pass 1a: 1267 // Compare scratch_cp entries to the old_cp entries that we have 1268 // already copied to *merge_cp_p. In this pass, we are eliminating 1269 // exact duplicates (matching entry at same index) so we only 1270 // compare entries in the common indice range. 1271 int increment = 1; 1272 int pass1a_length = MIN2(old_cp->length(), scratch_cp->length()); 1273 for (scratch_i = 1; scratch_i < pass1a_length; scratch_i += increment) { 1274 switch (scratch_cp->tag_at(scratch_i).value()) { 1275 case JVM_CONSTANT_Double: 1276 case JVM_CONSTANT_Long: 1277 // double and long take two constant pool entries 1278 increment = 2; 1279 break; 1280 1281 default: 1282 increment = 1; 1283 break; 1284 } 1285 1286 bool match = scratch_cp->compare_entry_to(scratch_i, *merge_cp_p, 1287 scratch_i, CHECK_0); 1288 if (match) { 1289 // found a match at the same index so nothing more to do 1290 continue; 1291 } else if (is_unresolved_class_mismatch(scratch_cp, scratch_i, 1292 *merge_cp_p, scratch_i)) { 1293 // The mismatch in compare_entry_to() above is because of a 1294 // resolved versus unresolved class entry at the same index 1295 // with the same string value. Since Pass 0 reverted any 1296 // class entries to unresolved class entries in *merge_cp_p, 1297 // we go with the unresolved class entry. 1298 continue; 1299 } 1300 1301 int found_i = scratch_cp->find_matching_entry(scratch_i, *merge_cp_p, 1302 CHECK_0); 1303 if (found_i != 0) { 1304 guarantee(found_i != scratch_i, 1305 "compare_entry_to() and find_matching_entry() do not agree"); 1306 1307 // Found a matching entry somewhere else in *merge_cp_p so 1308 // just need a mapping entry. 1309 map_index(scratch_cp, scratch_i, found_i); 1310 continue; 1311 } 1312 1313 // The find_matching_entry() call above could fail to find a match 1314 // due to a resolved versus unresolved class or string entry situation 1315 // like we solved above with the is_unresolved_*_mismatch() calls. 1316 // However, we would have to call is_unresolved_*_mismatch() over 1317 // all of *merge_cp_p (potentially) and that doesn't seem to be 1318 // worth the time. 1319 1320 // No match found so we have to append this entry and any unique 1321 // referenced entries to *merge_cp_p. 1322 append_entry(scratch_cp, scratch_i, merge_cp_p, merge_cp_length_p, 1323 CHECK_0); 1324 } 1325 } 1326 1327 RC_TRACE_WITH_THREAD(0x00020000, THREAD, 1328 ("after pass 1a: merge_cp_len=%d, scratch_i=%d, index_map_len=%d", 1329 *merge_cp_length_p, scratch_i, _index_map_count)); 1330 1331 if (scratch_i < scratch_cp->length()) { 1332 // Pass 1b: 1333 // old_cp is smaller than scratch_cp so there are entries in 1334 // scratch_cp that we have not yet processed. We take care of 1335 // those now. 1336 int increment = 1; 1337 for (; scratch_i < scratch_cp->length(); scratch_i += increment) { 1338 switch (scratch_cp->tag_at(scratch_i).value()) { 1339 case JVM_CONSTANT_Double: 1340 case JVM_CONSTANT_Long: 1341 // double and long take two constant pool entries 1342 increment = 2; 1343 break; 1344 1345 default: 1346 increment = 1; 1347 break; 1348 } 1349 1350 int found_i = 1351 scratch_cp->find_matching_entry(scratch_i, *merge_cp_p, CHECK_0); 1352 if (found_i != 0) { 1353 // Found a matching entry somewhere else in *merge_cp_p so 1354 // just need a mapping entry. 1355 map_index(scratch_cp, scratch_i, found_i); 1356 continue; 1357 } 1358 1359 // No match found so we have to append this entry and any unique 1360 // referenced entries to *merge_cp_p. 1361 append_entry(scratch_cp, scratch_i, merge_cp_p, merge_cp_length_p, 1362 CHECK_0); 1363 } 1364 1365 RC_TRACE_WITH_THREAD(0x00020000, THREAD, 1366 ("after pass 1b: merge_cp_len=%d, scratch_i=%d, index_map_len=%d", 1367 *merge_cp_length_p, scratch_i, _index_map_count)); 1368 } 1369 finalize_operands_merge(*merge_cp_p, THREAD); 1370 1371 return true; 1372 } // end merge_constant_pools() 1373 1374 1375 // Scoped object to clean up the constant pool(s) created for merging 1376 class MergeCPCleaner { 1377 ClassLoaderData* _loader_data; 1378 ConstantPool* _cp; 1379 ConstantPool* _scratch_cp; 1380 public: 1381 MergeCPCleaner(ClassLoaderData* loader_data, ConstantPool* merge_cp) : 1382 _loader_data(loader_data), _cp(merge_cp), _scratch_cp(NULL) {} 1383 ~MergeCPCleaner() { 1384 _loader_data->add_to_deallocate_list(_cp); 1385 if (_scratch_cp != NULL) { 1386 _loader_data->add_to_deallocate_list(_scratch_cp); 1387 } 1388 } 1389 void add_scratch_cp(ConstantPool* scratch_cp) { _scratch_cp = scratch_cp; } 1390 }; 1391 1392 // Merge constant pools between the_class and scratch_class and 1393 // potentially rewrite bytecodes in scratch_class to use the merged 1394 // constant pool. 1395 jvmtiError VM_RedefineClasses::merge_cp_and_rewrite( 1396 instanceKlassHandle the_class, instanceKlassHandle scratch_class, 1397 TRAPS) { 1398 // worst case merged constant pool length is old and new combined 1399 int merge_cp_length = the_class->constants()->length() 1400 + scratch_class->constants()->length(); 1401 1402 // Constant pools are not easily reused so we allocate a new one 1403 // each time. 1404 // merge_cp is created unsafe for concurrent GC processing. It 1405 // should be marked safe before discarding it. Even though 1406 // garbage, if it crosses a card boundary, it may be scanned 1407 // in order to find the start of the first complete object on the card. 1408 ClassLoaderData* loader_data = the_class->class_loader_data(); 1409 ConstantPool* merge_cp_oop = 1410 ConstantPool::allocate(loader_data, 1411 merge_cp_length, 1412 CHECK_(JVMTI_ERROR_OUT_OF_MEMORY)); 1413 MergeCPCleaner cp_cleaner(loader_data, merge_cp_oop); 1414 1415 HandleMark hm(THREAD); // make sure handles are cleared before 1416 // MergeCPCleaner clears out merge_cp_oop 1417 constantPoolHandle merge_cp(THREAD, merge_cp_oop); 1418 1419 // Get constants() from the old class because it could have been rewritten 1420 // while we were at a safepoint allocating a new constant pool. 1421 constantPoolHandle old_cp(THREAD, the_class->constants()); 1422 constantPoolHandle scratch_cp(THREAD, scratch_class->constants()); 1423 1424 // If the length changed, the class was redefined out from under us. Return 1425 // an error. 1426 if (merge_cp_length != the_class->constants()->length() 1427 + scratch_class->constants()->length()) { 1428 return JVMTI_ERROR_INTERNAL; 1429 } 1430 1431 // Update the version number of the constant pool 1432 merge_cp->increment_and_save_version(old_cp->version()); 1433 1434 ResourceMark rm(THREAD); 1435 _index_map_count = 0; 1436 _index_map_p = new intArray(scratch_cp->length(), -1); 1437 1438 _operands_cur_length = ConstantPool::operand_array_length(old_cp->operands()); 1439 _operands_index_map_count = 0; 1440 _operands_index_map_p = new intArray( 1441 ConstantPool::operand_array_length(scratch_cp->operands()), -1); 1442 1443 // reference to the cp holder is needed for copy_operands() 1444 merge_cp->set_pool_holder(scratch_class()); 1445 bool result = merge_constant_pools(old_cp, scratch_cp, &merge_cp, 1446 &merge_cp_length, THREAD); 1447 merge_cp->set_pool_holder(NULL); 1448 1449 if (!result) { 1450 // The merge can fail due to memory allocation failure or due 1451 // to robustness checks. 1452 return JVMTI_ERROR_INTERNAL; 1453 } 1454 1455 RC_TRACE_WITH_THREAD(0x00010000, THREAD, 1456 ("merge_cp_len=%d, index_map_len=%d", merge_cp_length, _index_map_count)); 1457 1458 if (_index_map_count == 0) { 1459 // there is nothing to map between the new and merged constant pools 1460 1461 if (old_cp->length() == scratch_cp->length()) { 1462 // The old and new constant pools are the same length and the 1463 // index map is empty. This means that the three constant pools 1464 // are equivalent (but not the same). Unfortunately, the new 1465 // constant pool has not gone through link resolution nor have 1466 // the new class bytecodes gone through constant pool cache 1467 // rewriting so we can't use the old constant pool with the new 1468 // class. 1469 1470 // toss the merged constant pool at return 1471 } else if (old_cp->length() < scratch_cp->length()) { 1472 // The old constant pool has fewer entries than the new constant 1473 // pool and the index map is empty. This means the new constant 1474 // pool is a superset of the old constant pool. However, the old 1475 // class bytecodes have already gone through constant pool cache 1476 // rewriting so we can't use the new constant pool with the old 1477 // class. 1478 1479 // toss the merged constant pool at return 1480 } else { 1481 // The old constant pool has more entries than the new constant 1482 // pool and the index map is empty. This means that both the old 1483 // and merged constant pools are supersets of the new constant 1484 // pool. 1485 1486 // Replace the new constant pool with a shrunken copy of the 1487 // merged constant pool 1488 set_new_constant_pool(loader_data, scratch_class, merge_cp, merge_cp_length, 1489 CHECK_(JVMTI_ERROR_OUT_OF_MEMORY)); 1490 // The new constant pool replaces scratch_cp so have cleaner clean it up. 1491 // It can't be cleaned up while there are handles to it. 1492 cp_cleaner.add_scratch_cp(scratch_cp()); 1493 } 1494 } else { 1495 if (RC_TRACE_ENABLED(0x00040000)) { 1496 // don't want to loop unless we are tracing 1497 int count = 0; 1498 for (int i = 1; i < _index_map_p->length(); i++) { 1499 int value = _index_map_p->at(i); 1500 1501 if (value != -1) { 1502 RC_TRACE_WITH_THREAD(0x00040000, THREAD, 1503 ("index_map[%d]: old=%d new=%d", count, i, value)); 1504 count++; 1505 } 1506 } 1507 } 1508 1509 // We have entries mapped between the new and merged constant pools 1510 // so we have to rewrite some constant pool references. 1511 if (!rewrite_cp_refs(scratch_class, THREAD)) { 1512 return JVMTI_ERROR_INTERNAL; 1513 } 1514 1515 // Replace the new constant pool with a shrunken copy of the 1516 // merged constant pool so now the rewritten bytecodes have 1517 // valid references; the previous new constant pool will get 1518 // GCed. 1519 set_new_constant_pool(loader_data, scratch_class, merge_cp, merge_cp_length, 1520 CHECK_(JVMTI_ERROR_OUT_OF_MEMORY)); 1521 // The new constant pool replaces scratch_cp so have cleaner clean it up. 1522 // It can't be cleaned up while there are handles to it. 1523 cp_cleaner.add_scratch_cp(scratch_cp()); 1524 } 1525 1526 return JVMTI_ERROR_NONE; 1527 } // end merge_cp_and_rewrite() 1528 1529 1530 // Rewrite constant pool references in klass scratch_class. 1531 bool VM_RedefineClasses::rewrite_cp_refs(instanceKlassHandle scratch_class, 1532 TRAPS) { 1533 1534 // rewrite constant pool references in the methods: 1535 if (!rewrite_cp_refs_in_methods(scratch_class, THREAD)) { 1536 // propagate failure back to caller 1537 return false; 1538 } 1539 1540 // rewrite constant pool references in the class_annotations: 1541 if (!rewrite_cp_refs_in_class_annotations(scratch_class, THREAD)) { 1542 // propagate failure back to caller 1543 return false; 1544 } 1545 1546 // rewrite constant pool references in the fields_annotations: 1547 if (!rewrite_cp_refs_in_fields_annotations(scratch_class, THREAD)) { 1548 // propagate failure back to caller 1549 return false; 1550 } 1551 1552 // rewrite constant pool references in the methods_annotations: 1553 if (!rewrite_cp_refs_in_methods_annotations(scratch_class, THREAD)) { 1554 // propagate failure back to caller 1555 return false; 1556 } 1557 1558 // rewrite constant pool references in the methods_parameter_annotations: 1559 if (!rewrite_cp_refs_in_methods_parameter_annotations(scratch_class, 1560 THREAD)) { 1561 // propagate failure back to caller 1562 return false; 1563 } 1564 1565 // rewrite constant pool references in the methods_default_annotations: 1566 if (!rewrite_cp_refs_in_methods_default_annotations(scratch_class, 1567 THREAD)) { 1568 // propagate failure back to caller 1569 return false; 1570 } 1571 1572 // rewrite source file name index: 1573 u2 source_file_name_idx = scratch_class->source_file_name_index(); 1574 if (source_file_name_idx != 0) { 1575 u2 new_source_file_name_idx = find_new_index(source_file_name_idx); 1576 if (new_source_file_name_idx != 0) { 1577 scratch_class->set_source_file_name_index(new_source_file_name_idx); 1578 } 1579 } 1580 1581 // rewrite class generic signature index: 1582 u2 generic_signature_index = scratch_class->generic_signature_index(); 1583 if (generic_signature_index != 0) { 1584 u2 new_generic_signature_index = find_new_index(generic_signature_index); 1585 if (new_generic_signature_index != 0) { 1586 scratch_class->set_generic_signature_index(new_generic_signature_index); 1587 } 1588 } 1589 1590 return true; 1591 } // end rewrite_cp_refs() 1592 1593 // Rewrite constant pool references in the methods. 1594 bool VM_RedefineClasses::rewrite_cp_refs_in_methods( 1595 instanceKlassHandle scratch_class, TRAPS) { 1596 1597 Array<Method*>* methods = scratch_class->methods(); 1598 1599 if (methods == NULL || methods->length() == 0) { 1600 // no methods so nothing to do 1601 return true; 1602 } 1603 1604 // rewrite constant pool references in the methods: 1605 for (int i = methods->length() - 1; i >= 0; i--) { 1606 methodHandle method(THREAD, methods->at(i)); 1607 methodHandle new_method; 1608 rewrite_cp_refs_in_method(method, &new_method, THREAD); 1609 if (!new_method.is_null()) { 1610 // the method has been replaced so save the new method version 1611 // even in the case of an exception. original method is on the 1612 // deallocation list. 1613 methods->at_put(i, new_method()); 1614 } 1615 if (HAS_PENDING_EXCEPTION) { 1616 Symbol* ex_name = PENDING_EXCEPTION->klass()->name(); 1617 // RC_TRACE_WITH_THREAD macro has an embedded ResourceMark 1618 RC_TRACE_WITH_THREAD(0x00000002, THREAD, 1619 ("rewrite_cp_refs_in_method exception: '%s'", ex_name->as_C_string())); 1620 // Need to clear pending exception here as the super caller sets 1621 // the JVMTI_ERROR_INTERNAL if the returned value is false. 1622 CLEAR_PENDING_EXCEPTION; 1623 return false; 1624 } 1625 } 1626 1627 return true; 1628 } 1629 1630 1631 // Rewrite constant pool references in the specific method. This code 1632 // was adapted from Rewriter::rewrite_method(). 1633 void VM_RedefineClasses::rewrite_cp_refs_in_method(methodHandle method, 1634 methodHandle *new_method_p, TRAPS) { 1635 1636 *new_method_p = methodHandle(); // default is no new method 1637 1638 // We cache a pointer to the bytecodes here in code_base. If GC 1639 // moves the Method*, then the bytecodes will also move which 1640 // will likely cause a crash. We create a No_Safepoint_Verifier 1641 // object to detect whether we pass a possible safepoint in this 1642 // code block. 1643 No_Safepoint_Verifier nsv; 1644 1645 // Bytecodes and their length 1646 address code_base = method->code_base(); 1647 int code_length = method->code_size(); 1648 1649 int bc_length; 1650 for (int bci = 0; bci < code_length; bci += bc_length) { 1651 address bcp = code_base + bci; 1652 Bytecodes::Code c = (Bytecodes::Code)(*bcp); 1653 1654 bc_length = Bytecodes::length_for(c); 1655 if (bc_length == 0) { 1656 // More complicated bytecodes report a length of zero so 1657 // we have to try again a slightly different way. 1658 bc_length = Bytecodes::length_at(method(), bcp); 1659 } 1660 1661 assert(bc_length != 0, "impossible bytecode length"); 1662 1663 switch (c) { 1664 case Bytecodes::_ldc: 1665 { 1666 int cp_index = *(bcp + 1); 1667 int new_index = find_new_index(cp_index); 1668 1669 if (StressLdcRewrite && new_index == 0) { 1670 // If we are stressing ldc -> ldc_w rewriting, then we 1671 // always need a new_index value. 1672 new_index = cp_index; 1673 } 1674 if (new_index != 0) { 1675 // the original index is mapped so we have more work to do 1676 if (!StressLdcRewrite && new_index <= max_jubyte) { 1677 // The new value can still use ldc instead of ldc_w 1678 // unless we are trying to stress ldc -> ldc_w rewriting 1679 RC_TRACE_WITH_THREAD(0x00080000, THREAD, 1680 ("%s@" INTPTR_FORMAT " old=%d, new=%d", Bytecodes::name(c), 1681 bcp, cp_index, new_index)); 1682 *(bcp + 1) = new_index; 1683 } else { 1684 RC_TRACE_WITH_THREAD(0x00080000, THREAD, 1685 ("%s->ldc_w@" INTPTR_FORMAT " old=%d, new=%d", 1686 Bytecodes::name(c), bcp, cp_index, new_index)); 1687 // the new value needs ldc_w instead of ldc 1688 u_char inst_buffer[4]; // max instruction size is 4 bytes 1689 bcp = (address)inst_buffer; 1690 // construct new instruction sequence 1691 *bcp = Bytecodes::_ldc_w; 1692 bcp++; 1693 // Rewriter::rewrite_method() does not rewrite ldc -> ldc_w. 1694 // See comment below for difference between put_Java_u2() 1695 // and put_native_u2(). 1696 Bytes::put_Java_u2(bcp, new_index); 1697 1698 Relocator rc(method, NULL /* no RelocatorListener needed */); 1699 methodHandle m; 1700 { 1701 Pause_No_Safepoint_Verifier pnsv(&nsv); 1702 1703 // ldc is 2 bytes and ldc_w is 3 bytes 1704 m = rc.insert_space_at(bci, 3, inst_buffer, CHECK); 1705 } 1706 1707 // return the new method so that the caller can update 1708 // the containing class 1709 *new_method_p = method = m; 1710 // switch our bytecode processing loop from the old method 1711 // to the new method 1712 code_base = method->code_base(); 1713 code_length = method->code_size(); 1714 bcp = code_base + bci; 1715 c = (Bytecodes::Code)(*bcp); 1716 bc_length = Bytecodes::length_for(c); 1717 assert(bc_length != 0, "sanity check"); 1718 } // end we need ldc_w instead of ldc 1719 } // end if there is a mapped index 1720 } break; 1721 1722 // these bytecodes have a two-byte constant pool index 1723 case Bytecodes::_anewarray : // fall through 1724 case Bytecodes::_checkcast : // fall through 1725 case Bytecodes::_getfield : // fall through 1726 case Bytecodes::_getstatic : // fall through 1727 case Bytecodes::_instanceof : // fall through 1728 case Bytecodes::_invokedynamic : // fall through 1729 case Bytecodes::_invokeinterface: // fall through 1730 case Bytecodes::_invokespecial : // fall through 1731 case Bytecodes::_invokestatic : // fall through 1732 case Bytecodes::_invokevirtual : // fall through 1733 case Bytecodes::_ldc_w : // fall through 1734 case Bytecodes::_ldc2_w : // fall through 1735 case Bytecodes::_multianewarray : // fall through 1736 case Bytecodes::_new : // fall through 1737 case Bytecodes::_putfield : // fall through 1738 case Bytecodes::_putstatic : 1739 { 1740 address p = bcp + 1; 1741 int cp_index = Bytes::get_Java_u2(p); 1742 int new_index = find_new_index(cp_index); 1743 if (new_index != 0) { 1744 // the original index is mapped so update w/ new value 1745 RC_TRACE_WITH_THREAD(0x00080000, THREAD, 1746 ("%s@" INTPTR_FORMAT " old=%d, new=%d", Bytecodes::name(c), 1747 bcp, cp_index, new_index)); 1748 // Rewriter::rewrite_method() uses put_native_u2() in this 1749 // situation because it is reusing the constant pool index 1750 // location for a native index into the ConstantPoolCache. 1751 // Since we are updating the constant pool index prior to 1752 // verification and ConstantPoolCache initialization, we 1753 // need to keep the new index in Java byte order. 1754 Bytes::put_Java_u2(p, new_index); 1755 } 1756 } break; 1757 } 1758 } // end for each bytecode 1759 1760 // We also need to rewrite the parameter name indexes, if there is 1761 // method parameter data present 1762 if(method->has_method_parameters()) { 1763 const int len = method->method_parameters_length(); 1764 MethodParametersElement* elem = method->method_parameters_start(); 1765 1766 for (int i = 0; i < len; i++) { 1767 const u2 cp_index = elem[i].name_cp_index; 1768 const u2 new_cp_index = find_new_index(cp_index); 1769 if (new_cp_index != 0) { 1770 elem[i].name_cp_index = new_cp_index; 1771 } 1772 } 1773 } 1774 } // end rewrite_cp_refs_in_method() 1775 1776 1777 // Rewrite constant pool references in the class_annotations field. 1778 bool VM_RedefineClasses::rewrite_cp_refs_in_class_annotations( 1779 instanceKlassHandle scratch_class, TRAPS) { 1780 1781 AnnotationArray* class_annotations = scratch_class->class_annotations(); 1782 if (class_annotations == NULL || class_annotations->length() == 0) { 1783 // no class_annotations so nothing to do 1784 return true; 1785 } 1786 1787 RC_TRACE_WITH_THREAD(0x02000000, THREAD, 1788 ("class_annotations length=%d", class_annotations->length())); 1789 1790 int byte_i = 0; // byte index into class_annotations 1791 return rewrite_cp_refs_in_annotations_typeArray(class_annotations, byte_i, 1792 THREAD); 1793 } 1794 1795 1796 // Rewrite constant pool references in an annotations typeArray. This 1797 // "structure" is adapted from the RuntimeVisibleAnnotations_attribute 1798 // that is described in section 4.8.15 of the 2nd-edition of the VM spec: 1799 // 1800 // annotations_typeArray { 1801 // u2 num_annotations; 1802 // annotation annotations[num_annotations]; 1803 // } 1804 // 1805 bool VM_RedefineClasses::rewrite_cp_refs_in_annotations_typeArray( 1806 AnnotationArray* annotations_typeArray, int &byte_i_ref, TRAPS) { 1807 1808 if ((byte_i_ref + 2) > annotations_typeArray->length()) { 1809 // not enough room for num_annotations field 1810 RC_TRACE_WITH_THREAD(0x02000000, THREAD, 1811 ("length() is too small for num_annotations field")); 1812 return false; 1813 } 1814 1815 u2 num_annotations = Bytes::get_Java_u2((address) 1816 annotations_typeArray->adr_at(byte_i_ref)); 1817 byte_i_ref += 2; 1818 1819 RC_TRACE_WITH_THREAD(0x02000000, THREAD, 1820 ("num_annotations=%d", num_annotations)); 1821 1822 int calc_num_annotations = 0; 1823 for (; calc_num_annotations < num_annotations; calc_num_annotations++) { 1824 if (!rewrite_cp_refs_in_annotation_struct(annotations_typeArray, 1825 byte_i_ref, THREAD)) { 1826 RC_TRACE_WITH_THREAD(0x02000000, THREAD, 1827 ("bad annotation_struct at %d", calc_num_annotations)); 1828 // propagate failure back to caller 1829 return false; 1830 } 1831 } 1832 assert(num_annotations == calc_num_annotations, "sanity check"); 1833 1834 return true; 1835 } // end rewrite_cp_refs_in_annotations_typeArray() 1836 1837 1838 // Rewrite constant pool references in the annotation struct portion of 1839 // an annotations_typeArray. This "structure" is from section 4.8.15 of 1840 // the 2nd-edition of the VM spec: 1841 // 1842 // struct annotation { 1843 // u2 type_index; 1844 // u2 num_element_value_pairs; 1845 // { 1846 // u2 element_name_index; 1847 // element_value value; 1848 // } element_value_pairs[num_element_value_pairs]; 1849 // } 1850 // 1851 bool VM_RedefineClasses::rewrite_cp_refs_in_annotation_struct( 1852 AnnotationArray* annotations_typeArray, int &byte_i_ref, TRAPS) { 1853 if ((byte_i_ref + 2 + 2) > annotations_typeArray->length()) { 1854 // not enough room for smallest annotation_struct 1855 RC_TRACE_WITH_THREAD(0x02000000, THREAD, 1856 ("length() is too small for annotation_struct")); 1857 return false; 1858 } 1859 1860 u2 type_index = rewrite_cp_ref_in_annotation_data(annotations_typeArray, 1861 byte_i_ref, "mapped old type_index=%d", THREAD); 1862 1863 u2 num_element_value_pairs = Bytes::get_Java_u2((address) 1864 annotations_typeArray->adr_at(byte_i_ref)); 1865 byte_i_ref += 2; 1866 1867 RC_TRACE_WITH_THREAD(0x02000000, THREAD, 1868 ("type_index=%d num_element_value_pairs=%d", type_index, 1869 num_element_value_pairs)); 1870 1871 int calc_num_element_value_pairs = 0; 1872 for (; calc_num_element_value_pairs < num_element_value_pairs; 1873 calc_num_element_value_pairs++) { 1874 if ((byte_i_ref + 2) > annotations_typeArray->length()) { 1875 // not enough room for another element_name_index, let alone 1876 // the rest of another component 1877 RC_TRACE_WITH_THREAD(0x02000000, THREAD, 1878 ("length() is too small for element_name_index")); 1879 return false; 1880 } 1881 1882 u2 element_name_index = rewrite_cp_ref_in_annotation_data( 1883 annotations_typeArray, byte_i_ref, 1884 "mapped old element_name_index=%d", THREAD); 1885 1886 RC_TRACE_WITH_THREAD(0x02000000, THREAD, 1887 ("element_name_index=%d", element_name_index)); 1888 1889 if (!rewrite_cp_refs_in_element_value(annotations_typeArray, 1890 byte_i_ref, THREAD)) { 1891 RC_TRACE_WITH_THREAD(0x02000000, THREAD, 1892 ("bad element_value at %d", calc_num_element_value_pairs)); 1893 // propagate failure back to caller 1894 return false; 1895 } 1896 } // end for each component 1897 assert(num_element_value_pairs == calc_num_element_value_pairs, 1898 "sanity check"); 1899 1900 return true; 1901 } // end rewrite_cp_refs_in_annotation_struct() 1902 1903 1904 // Rewrite a constant pool reference at the current position in 1905 // annotations_typeArray if needed. Returns the original constant 1906 // pool reference if a rewrite was not needed or the new constant 1907 // pool reference if a rewrite was needed. 1908 PRAGMA_DIAG_PUSH 1909 PRAGMA_FORMAT_NONLITERAL_IGNORED 1910 u2 VM_RedefineClasses::rewrite_cp_ref_in_annotation_data( 1911 AnnotationArray* annotations_typeArray, int &byte_i_ref, 1912 const char * trace_mesg, TRAPS) { 1913 1914 address cp_index_addr = (address) 1915 annotations_typeArray->adr_at(byte_i_ref); 1916 u2 old_cp_index = Bytes::get_Java_u2(cp_index_addr); 1917 u2 new_cp_index = find_new_index(old_cp_index); 1918 if (new_cp_index != 0) { 1919 RC_TRACE_WITH_THREAD(0x02000000, THREAD, (trace_mesg, old_cp_index)); 1920 Bytes::put_Java_u2(cp_index_addr, new_cp_index); 1921 old_cp_index = new_cp_index; 1922 } 1923 byte_i_ref += 2; 1924 return old_cp_index; 1925 } 1926 PRAGMA_DIAG_POP 1927 1928 1929 // Rewrite constant pool references in the element_value portion of an 1930 // annotations_typeArray. This "structure" is from section 4.8.15.1 of 1931 // the 2nd-edition of the VM spec: 1932 // 1933 // struct element_value { 1934 // u1 tag; 1935 // union { 1936 // u2 const_value_index; 1937 // { 1938 // u2 type_name_index; 1939 // u2 const_name_index; 1940 // } enum_const_value; 1941 // u2 class_info_index; 1942 // annotation annotation_value; 1943 // struct { 1944 // u2 num_values; 1945 // element_value values[num_values]; 1946 // } array_value; 1947 // } value; 1948 // } 1949 // 1950 bool VM_RedefineClasses::rewrite_cp_refs_in_element_value( 1951 AnnotationArray* annotations_typeArray, int &byte_i_ref, TRAPS) { 1952 1953 if ((byte_i_ref + 1) > annotations_typeArray->length()) { 1954 // not enough room for a tag let alone the rest of an element_value 1955 RC_TRACE_WITH_THREAD(0x02000000, THREAD, 1956 ("length() is too small for a tag")); 1957 return false; 1958 } 1959 1960 u1 tag = annotations_typeArray->at(byte_i_ref); 1961 byte_i_ref++; 1962 RC_TRACE_WITH_THREAD(0x02000000, THREAD, ("tag='%c'", tag)); 1963 1964 switch (tag) { 1965 // These BaseType tag values are from Table 4.2 in VM spec: 1966 case 'B': // byte 1967 case 'C': // char 1968 case 'D': // double 1969 case 'F': // float 1970 case 'I': // int 1971 case 'J': // long 1972 case 'S': // short 1973 case 'Z': // boolean 1974 1975 // The remaining tag values are from Table 4.8 in the 2nd-edition of 1976 // the VM spec: 1977 case 's': 1978 { 1979 // For the above tag values (including the BaseType values), 1980 // value.const_value_index is right union field. 1981 1982 if ((byte_i_ref + 2) > annotations_typeArray->length()) { 1983 // not enough room for a const_value_index 1984 RC_TRACE_WITH_THREAD(0x02000000, THREAD, 1985 ("length() is too small for a const_value_index")); 1986 return false; 1987 } 1988 1989 u2 const_value_index = rewrite_cp_ref_in_annotation_data( 1990 annotations_typeArray, byte_i_ref, 1991 "mapped old const_value_index=%d", THREAD); 1992 1993 RC_TRACE_WITH_THREAD(0x02000000, THREAD, 1994 ("const_value_index=%d", const_value_index)); 1995 } break; 1996 1997 case 'e': 1998 { 1999 // for the above tag value, value.enum_const_value is right union field 2000 2001 if ((byte_i_ref + 4) > annotations_typeArray->length()) { 2002 // not enough room for a enum_const_value 2003 RC_TRACE_WITH_THREAD(0x02000000, THREAD, 2004 ("length() is too small for a enum_const_value")); 2005 return false; 2006 } 2007 2008 u2 type_name_index = rewrite_cp_ref_in_annotation_data( 2009 annotations_typeArray, byte_i_ref, 2010 "mapped old type_name_index=%d", THREAD); 2011 2012 u2 const_name_index = rewrite_cp_ref_in_annotation_data( 2013 annotations_typeArray, byte_i_ref, 2014 "mapped old const_name_index=%d", THREAD); 2015 2016 RC_TRACE_WITH_THREAD(0x02000000, THREAD, 2017 ("type_name_index=%d const_name_index=%d", type_name_index, 2018 const_name_index)); 2019 } break; 2020 2021 case 'c': 2022 { 2023 // for the above tag value, value.class_info_index is right union field 2024 2025 if ((byte_i_ref + 2) > annotations_typeArray->length()) { 2026 // not enough room for a class_info_index 2027 RC_TRACE_WITH_THREAD(0x02000000, THREAD, 2028 ("length() is too small for a class_info_index")); 2029 return false; 2030 } 2031 2032 u2 class_info_index = rewrite_cp_ref_in_annotation_data( 2033 annotations_typeArray, byte_i_ref, 2034 "mapped old class_info_index=%d", THREAD); 2035 2036 RC_TRACE_WITH_THREAD(0x02000000, THREAD, 2037 ("class_info_index=%d", class_info_index)); 2038 } break; 2039 2040 case '@': 2041 // For the above tag value, value.attr_value is the right union 2042 // field. This is a nested annotation. 2043 if (!rewrite_cp_refs_in_annotation_struct(annotations_typeArray, 2044 byte_i_ref, THREAD)) { 2045 // propagate failure back to caller 2046 return false; 2047 } 2048 break; 2049 2050 case '[': 2051 { 2052 if ((byte_i_ref + 2) > annotations_typeArray->length()) { 2053 // not enough room for a num_values field 2054 RC_TRACE_WITH_THREAD(0x02000000, THREAD, 2055 ("length() is too small for a num_values field")); 2056 return false; 2057 } 2058 2059 // For the above tag value, value.array_value is the right union 2060 // field. This is an array of nested element_value. 2061 u2 num_values = Bytes::get_Java_u2((address) 2062 annotations_typeArray->adr_at(byte_i_ref)); 2063 byte_i_ref += 2; 2064 RC_TRACE_WITH_THREAD(0x02000000, THREAD, ("num_values=%d", num_values)); 2065 2066 int calc_num_values = 0; 2067 for (; calc_num_values < num_values; calc_num_values++) { 2068 if (!rewrite_cp_refs_in_element_value( 2069 annotations_typeArray, byte_i_ref, THREAD)) { 2070 RC_TRACE_WITH_THREAD(0x02000000, THREAD, 2071 ("bad nested element_value at %d", calc_num_values)); 2072 // propagate failure back to caller 2073 return false; 2074 } 2075 } 2076 assert(num_values == calc_num_values, "sanity check"); 2077 } break; 2078 2079 default: 2080 RC_TRACE_WITH_THREAD(0x02000000, THREAD, ("bad tag=0x%x", tag)); 2081 return false; 2082 } // end decode tag field 2083 2084 return true; 2085 } // end rewrite_cp_refs_in_element_value() 2086 2087 2088 // Rewrite constant pool references in a fields_annotations field. 2089 bool VM_RedefineClasses::rewrite_cp_refs_in_fields_annotations( 2090 instanceKlassHandle scratch_class, TRAPS) { 2091 2092 Array<AnnotationArray*>* fields_annotations = scratch_class->fields_annotations(); 2093 2094 if (fields_annotations == NULL || fields_annotations->length() == 0) { 2095 // no fields_annotations so nothing to do 2096 return true; 2097 } 2098 2099 RC_TRACE_WITH_THREAD(0x02000000, THREAD, 2100 ("fields_annotations length=%d", fields_annotations->length())); 2101 2102 for (int i = 0; i < fields_annotations->length(); i++) { 2103 AnnotationArray* field_annotations = fields_annotations->at(i); 2104 if (field_annotations == NULL || field_annotations->length() == 0) { 2105 // this field does not have any annotations so skip it 2106 continue; 2107 } 2108 2109 int byte_i = 0; // byte index into field_annotations 2110 if (!rewrite_cp_refs_in_annotations_typeArray(field_annotations, byte_i, 2111 THREAD)) { 2112 RC_TRACE_WITH_THREAD(0x02000000, THREAD, 2113 ("bad field_annotations at %d", i)); 2114 // propagate failure back to caller 2115 return false; 2116 } 2117 } 2118 2119 return true; 2120 } // end rewrite_cp_refs_in_fields_annotations() 2121 2122 2123 // Rewrite constant pool references in a methods_annotations field. 2124 bool VM_RedefineClasses::rewrite_cp_refs_in_methods_annotations( 2125 instanceKlassHandle scratch_class, TRAPS) { 2126 2127 for (int i = 0; i < scratch_class->methods()->length(); i++) { 2128 Method* m = scratch_class->methods()->at(i); 2129 AnnotationArray* method_annotations = m->constMethod()->method_annotations(); 2130 2131 if (method_annotations == NULL || method_annotations->length() == 0) { 2132 // this method does not have any annotations so skip it 2133 continue; 2134 } 2135 2136 int byte_i = 0; // byte index into method_annotations 2137 if (!rewrite_cp_refs_in_annotations_typeArray(method_annotations, byte_i, 2138 THREAD)) { 2139 RC_TRACE_WITH_THREAD(0x02000000, THREAD, 2140 ("bad method_annotations at %d", i)); 2141 // propagate failure back to caller 2142 return false; 2143 } 2144 } 2145 2146 return true; 2147 } // end rewrite_cp_refs_in_methods_annotations() 2148 2149 2150 // Rewrite constant pool references in a methods_parameter_annotations 2151 // field. This "structure" is adapted from the 2152 // RuntimeVisibleParameterAnnotations_attribute described in section 2153 // 4.8.17 of the 2nd-edition of the VM spec: 2154 // 2155 // methods_parameter_annotations_typeArray { 2156 // u1 num_parameters; 2157 // { 2158 // u2 num_annotations; 2159 // annotation annotations[num_annotations]; 2160 // } parameter_annotations[num_parameters]; 2161 // } 2162 // 2163 bool VM_RedefineClasses::rewrite_cp_refs_in_methods_parameter_annotations( 2164 instanceKlassHandle scratch_class, TRAPS) { 2165 2166 for (int i = 0; i < scratch_class->methods()->length(); i++) { 2167 Method* m = scratch_class->methods()->at(i); 2168 AnnotationArray* method_parameter_annotations = m->constMethod()->parameter_annotations(); 2169 if (method_parameter_annotations == NULL 2170 || method_parameter_annotations->length() == 0) { 2171 // this method does not have any parameter annotations so skip it 2172 continue; 2173 } 2174 2175 if (method_parameter_annotations->length() < 1) { 2176 // not enough room for a num_parameters field 2177 RC_TRACE_WITH_THREAD(0x02000000, THREAD, 2178 ("length() is too small for a num_parameters field at %d", i)); 2179 return false; 2180 } 2181 2182 int byte_i = 0; // byte index into method_parameter_annotations 2183 2184 u1 num_parameters = method_parameter_annotations->at(byte_i); 2185 byte_i++; 2186 2187 RC_TRACE_WITH_THREAD(0x02000000, THREAD, 2188 ("num_parameters=%d", num_parameters)); 2189 2190 int calc_num_parameters = 0; 2191 for (; calc_num_parameters < num_parameters; calc_num_parameters++) { 2192 if (!rewrite_cp_refs_in_annotations_typeArray( 2193 method_parameter_annotations, byte_i, THREAD)) { 2194 RC_TRACE_WITH_THREAD(0x02000000, THREAD, 2195 ("bad method_parameter_annotations at %d", calc_num_parameters)); 2196 // propagate failure back to caller 2197 return false; 2198 } 2199 } 2200 assert(num_parameters == calc_num_parameters, "sanity check"); 2201 } 2202 2203 return true; 2204 } // end rewrite_cp_refs_in_methods_parameter_annotations() 2205 2206 2207 // Rewrite constant pool references in a methods_default_annotations 2208 // field. This "structure" is adapted from the AnnotationDefault_attribute 2209 // that is described in section 4.8.19 of the 2nd-edition of the VM spec: 2210 // 2211 // methods_default_annotations_typeArray { 2212 // element_value default_value; 2213 // } 2214 // 2215 bool VM_RedefineClasses::rewrite_cp_refs_in_methods_default_annotations( 2216 instanceKlassHandle scratch_class, TRAPS) { 2217 2218 for (int i = 0; i < scratch_class->methods()->length(); i++) { 2219 Method* m = scratch_class->methods()->at(i); 2220 AnnotationArray* method_default_annotations = m->constMethod()->default_annotations(); 2221 if (method_default_annotations == NULL 2222 || method_default_annotations->length() == 0) { 2223 // this method does not have any default annotations so skip it 2224 continue; 2225 } 2226 2227 int byte_i = 0; // byte index into method_default_annotations 2228 2229 if (!rewrite_cp_refs_in_element_value( 2230 method_default_annotations, byte_i, THREAD)) { 2231 RC_TRACE_WITH_THREAD(0x02000000, THREAD, 2232 ("bad default element_value at %d", i)); 2233 // propagate failure back to caller 2234 return false; 2235 } 2236 } 2237 2238 return true; 2239 } // end rewrite_cp_refs_in_methods_default_annotations() 2240 2241 2242 // Rewrite constant pool references in the method's stackmap table. 2243 // These "structures" are adapted from the StackMapTable_attribute that 2244 // is described in section 4.8.4 of the 6.0 version of the VM spec 2245 // (dated 2005.10.26): 2246 // file:///net/quincunx.sfbay/export/gbracha/ClassFile-Java6.pdf 2247 // 2248 // stack_map { 2249 // u2 number_of_entries; 2250 // stack_map_frame entries[number_of_entries]; 2251 // } 2252 // 2253 void VM_RedefineClasses::rewrite_cp_refs_in_stack_map_table( 2254 methodHandle method, TRAPS) { 2255 2256 if (!method->has_stackmap_table()) { 2257 return; 2258 } 2259 2260 AnnotationArray* stackmap_data = method->stackmap_data(); 2261 address stackmap_p = (address)stackmap_data->adr_at(0); 2262 address stackmap_end = stackmap_p + stackmap_data->length(); 2263 2264 assert(stackmap_p + 2 <= stackmap_end, "no room for number_of_entries"); 2265 u2 number_of_entries = Bytes::get_Java_u2(stackmap_p); 2266 stackmap_p += 2; 2267 2268 RC_TRACE_WITH_THREAD(0x04000000, THREAD, 2269 ("number_of_entries=%u", number_of_entries)); 2270 2271 // walk through each stack_map_frame 2272 u2 calc_number_of_entries = 0; 2273 for (; calc_number_of_entries < number_of_entries; calc_number_of_entries++) { 2274 // The stack_map_frame structure is a u1 frame_type followed by 2275 // 0 or more bytes of data: 2276 // 2277 // union stack_map_frame { 2278 // same_frame; 2279 // same_locals_1_stack_item_frame; 2280 // same_locals_1_stack_item_frame_extended; 2281 // chop_frame; 2282 // same_frame_extended; 2283 // append_frame; 2284 // full_frame; 2285 // } 2286 2287 assert(stackmap_p + 1 <= stackmap_end, "no room for frame_type"); 2288 // The Linux compiler does not like frame_type to be u1 or u2. It 2289 // issues the following warning for the first if-statement below: 2290 // 2291 // "warning: comparison is always true due to limited range of data type" 2292 // 2293 u4 frame_type = *stackmap_p; 2294 stackmap_p++; 2295 2296 // same_frame { 2297 // u1 frame_type = SAME; /* 0-63 */ 2298 // } 2299 if (frame_type >= 0 && frame_type <= 63) { 2300 // nothing more to do for same_frame 2301 } 2302 2303 // same_locals_1_stack_item_frame { 2304 // u1 frame_type = SAME_LOCALS_1_STACK_ITEM; /* 64-127 */ 2305 // verification_type_info stack[1]; 2306 // } 2307 else if (frame_type >= 64 && frame_type <= 127) { 2308 rewrite_cp_refs_in_verification_type_info(stackmap_p, stackmap_end, 2309 calc_number_of_entries, frame_type, THREAD); 2310 } 2311 2312 // reserved for future use 2313 else if (frame_type >= 128 && frame_type <= 246) { 2314 // nothing more to do for reserved frame_types 2315 } 2316 2317 // same_locals_1_stack_item_frame_extended { 2318 // u1 frame_type = SAME_LOCALS_1_STACK_ITEM_EXTENDED; /* 247 */ 2319 // u2 offset_delta; 2320 // verification_type_info stack[1]; 2321 // } 2322 else if (frame_type == 247) { 2323 stackmap_p += 2; 2324 rewrite_cp_refs_in_verification_type_info(stackmap_p, stackmap_end, 2325 calc_number_of_entries, frame_type, THREAD); 2326 } 2327 2328 // chop_frame { 2329 // u1 frame_type = CHOP; /* 248-250 */ 2330 // u2 offset_delta; 2331 // } 2332 else if (frame_type >= 248 && frame_type <= 250) { 2333 stackmap_p += 2; 2334 } 2335 2336 // same_frame_extended { 2337 // u1 frame_type = SAME_FRAME_EXTENDED; /* 251*/ 2338 // u2 offset_delta; 2339 // } 2340 else if (frame_type == 251) { 2341 stackmap_p += 2; 2342 } 2343 2344 // append_frame { 2345 // u1 frame_type = APPEND; /* 252-254 */ 2346 // u2 offset_delta; 2347 // verification_type_info locals[frame_type - 251]; 2348 // } 2349 else if (frame_type >= 252 && frame_type <= 254) { 2350 assert(stackmap_p + 2 <= stackmap_end, 2351 "no room for offset_delta"); 2352 stackmap_p += 2; 2353 u1 len = frame_type - 251; 2354 for (u1 i = 0; i < len; i++) { 2355 rewrite_cp_refs_in_verification_type_info(stackmap_p, stackmap_end, 2356 calc_number_of_entries, frame_type, THREAD); 2357 } 2358 } 2359 2360 // full_frame { 2361 // u1 frame_type = FULL_FRAME; /* 255 */ 2362 // u2 offset_delta; 2363 // u2 number_of_locals; 2364 // verification_type_info locals[number_of_locals]; 2365 // u2 number_of_stack_items; 2366 // verification_type_info stack[number_of_stack_items]; 2367 // } 2368 else if (frame_type == 255) { 2369 assert(stackmap_p + 2 + 2 <= stackmap_end, 2370 "no room for smallest full_frame"); 2371 stackmap_p += 2; 2372 2373 u2 number_of_locals = Bytes::get_Java_u2(stackmap_p); 2374 stackmap_p += 2; 2375 2376 for (u2 locals_i = 0; locals_i < number_of_locals; locals_i++) { 2377 rewrite_cp_refs_in_verification_type_info(stackmap_p, stackmap_end, 2378 calc_number_of_entries, frame_type, THREAD); 2379 } 2380 2381 // Use the largest size for the number_of_stack_items, but only get 2382 // the right number of bytes. 2383 u2 number_of_stack_items = Bytes::get_Java_u2(stackmap_p); 2384 stackmap_p += 2; 2385 2386 for (u2 stack_i = 0; stack_i < number_of_stack_items; stack_i++) { 2387 rewrite_cp_refs_in_verification_type_info(stackmap_p, stackmap_end, 2388 calc_number_of_entries, frame_type, THREAD); 2389 } 2390 } 2391 } // end while there is a stack_map_frame 2392 assert(number_of_entries == calc_number_of_entries, "sanity check"); 2393 } // end rewrite_cp_refs_in_stack_map_table() 2394 2395 2396 // Rewrite constant pool references in the verification type info 2397 // portion of the method's stackmap table. These "structures" are 2398 // adapted from the StackMapTable_attribute that is described in 2399 // section 4.8.4 of the 6.0 version of the VM spec (dated 2005.10.26): 2400 // file:///net/quincunx.sfbay/export/gbracha/ClassFile-Java6.pdf 2401 // 2402 // The verification_type_info structure is a u1 tag followed by 0 or 2403 // more bytes of data: 2404 // 2405 // union verification_type_info { 2406 // Top_variable_info; 2407 // Integer_variable_info; 2408 // Float_variable_info; 2409 // Long_variable_info; 2410 // Double_variable_info; 2411 // Null_variable_info; 2412 // UninitializedThis_variable_info; 2413 // Object_variable_info; 2414 // Uninitialized_variable_info; 2415 // } 2416 // 2417 void VM_RedefineClasses::rewrite_cp_refs_in_verification_type_info( 2418 address& stackmap_p_ref, address stackmap_end, u2 frame_i, 2419 u1 frame_type, TRAPS) { 2420 2421 assert(stackmap_p_ref + 1 <= stackmap_end, "no room for tag"); 2422 u1 tag = *stackmap_p_ref; 2423 stackmap_p_ref++; 2424 2425 switch (tag) { 2426 // Top_variable_info { 2427 // u1 tag = ITEM_Top; /* 0 */ 2428 // } 2429 // verificationType.hpp has zero as ITEM_Bogus instead of ITEM_Top 2430 case 0: // fall through 2431 2432 // Integer_variable_info { 2433 // u1 tag = ITEM_Integer; /* 1 */ 2434 // } 2435 case ITEM_Integer: // fall through 2436 2437 // Float_variable_info { 2438 // u1 tag = ITEM_Float; /* 2 */ 2439 // } 2440 case ITEM_Float: // fall through 2441 2442 // Double_variable_info { 2443 // u1 tag = ITEM_Double; /* 3 */ 2444 // } 2445 case ITEM_Double: // fall through 2446 2447 // Long_variable_info { 2448 // u1 tag = ITEM_Long; /* 4 */ 2449 // } 2450 case ITEM_Long: // fall through 2451 2452 // Null_variable_info { 2453 // u1 tag = ITEM_Null; /* 5 */ 2454 // } 2455 case ITEM_Null: // fall through 2456 2457 // UninitializedThis_variable_info { 2458 // u1 tag = ITEM_UninitializedThis; /* 6 */ 2459 // } 2460 case ITEM_UninitializedThis: 2461 // nothing more to do for the above tag types 2462 break; 2463 2464 // Object_variable_info { 2465 // u1 tag = ITEM_Object; /* 7 */ 2466 // u2 cpool_index; 2467 // } 2468 case ITEM_Object: 2469 { 2470 assert(stackmap_p_ref + 2 <= stackmap_end, "no room for cpool_index"); 2471 u2 cpool_index = Bytes::get_Java_u2(stackmap_p_ref); 2472 u2 new_cp_index = find_new_index(cpool_index); 2473 if (new_cp_index != 0) { 2474 RC_TRACE_WITH_THREAD(0x04000000, THREAD, 2475 ("mapped old cpool_index=%d", cpool_index)); 2476 Bytes::put_Java_u2(stackmap_p_ref, new_cp_index); 2477 cpool_index = new_cp_index; 2478 } 2479 stackmap_p_ref += 2; 2480 2481 RC_TRACE_WITH_THREAD(0x04000000, THREAD, 2482 ("frame_i=%u, frame_type=%u, cpool_index=%d", frame_i, 2483 frame_type, cpool_index)); 2484 } break; 2485 2486 // Uninitialized_variable_info { 2487 // u1 tag = ITEM_Uninitialized; /* 8 */ 2488 // u2 offset; 2489 // } 2490 case ITEM_Uninitialized: 2491 assert(stackmap_p_ref + 2 <= stackmap_end, "no room for offset"); 2492 stackmap_p_ref += 2; 2493 break; 2494 2495 default: 2496 RC_TRACE_WITH_THREAD(0x04000000, THREAD, 2497 ("frame_i=%u, frame_type=%u, bad tag=0x%x", frame_i, frame_type, tag)); 2498 ShouldNotReachHere(); 2499 break; 2500 } // end switch (tag) 2501 } // end rewrite_cp_refs_in_verification_type_info() 2502 2503 2504 // Change the constant pool associated with klass scratch_class to 2505 // scratch_cp. If shrink is true, then scratch_cp_length elements 2506 // are copied from scratch_cp to a smaller constant pool and the 2507 // smaller constant pool is associated with scratch_class. 2508 void VM_RedefineClasses::set_new_constant_pool( 2509 ClassLoaderData* loader_data, 2510 instanceKlassHandle scratch_class, constantPoolHandle scratch_cp, 2511 int scratch_cp_length, TRAPS) { 2512 assert(scratch_cp->length() >= scratch_cp_length, "sanity check"); 2513 2514 // scratch_cp is a merged constant pool and has enough space for a 2515 // worst case merge situation. We want to associate the minimum 2516 // sized constant pool with the klass to save space. 2517 ConstantPool* cp = ConstantPool::allocate(loader_data, scratch_cp_length, CHECK); 2518 constantPoolHandle smaller_cp(THREAD, cp); 2519 2520 // preserve version() value in the smaller copy 2521 int version = scratch_cp->version(); 2522 assert(version != 0, "sanity check"); 2523 smaller_cp->set_version(version); 2524 2525 // attach klass to new constant pool 2526 // reference to the cp holder is needed for copy_operands() 2527 smaller_cp->set_pool_holder(scratch_class()); 2528 2529 scratch_cp->copy_cp_to(1, scratch_cp_length - 1, smaller_cp, 1, THREAD); 2530 if (HAS_PENDING_EXCEPTION) { 2531 // Exception is handled in the caller 2532 loader_data->add_to_deallocate_list(smaller_cp()); 2533 return; 2534 } 2535 scratch_cp = smaller_cp; 2536 2537 // attach new constant pool to klass 2538 scratch_class->set_constants(scratch_cp()); 2539 2540 int i; // for portability 2541 2542 // update each field in klass to use new constant pool indices as needed 2543 for (JavaFieldStream fs(scratch_class); !fs.done(); fs.next()) { 2544 jshort cur_index = fs.name_index(); 2545 jshort new_index = find_new_index(cur_index); 2546 if (new_index != 0) { 2547 RC_TRACE_WITH_THREAD(0x00080000, THREAD, 2548 ("field-name_index change: %d to %d", cur_index, new_index)); 2549 fs.set_name_index(new_index); 2550 } 2551 cur_index = fs.signature_index(); 2552 new_index = find_new_index(cur_index); 2553 if (new_index != 0) { 2554 RC_TRACE_WITH_THREAD(0x00080000, THREAD, 2555 ("field-signature_index change: %d to %d", cur_index, new_index)); 2556 fs.set_signature_index(new_index); 2557 } 2558 cur_index = fs.initval_index(); 2559 new_index = find_new_index(cur_index); 2560 if (new_index != 0) { 2561 RC_TRACE_WITH_THREAD(0x00080000, THREAD, 2562 ("field-initval_index change: %d to %d", cur_index, new_index)); 2563 fs.set_initval_index(new_index); 2564 } 2565 cur_index = fs.generic_signature_index(); 2566 new_index = find_new_index(cur_index); 2567 if (new_index != 0) { 2568 RC_TRACE_WITH_THREAD(0x00080000, THREAD, 2569 ("field-generic_signature change: %d to %d", cur_index, new_index)); 2570 fs.set_generic_signature_index(new_index); 2571 } 2572 } // end for each field 2573 2574 // Update constant pool indices in the inner classes info to use 2575 // new constant indices as needed. The inner classes info is a 2576 // quadruple: 2577 // (inner_class_info, outer_class_info, inner_name, inner_access_flags) 2578 InnerClassesIterator iter(scratch_class); 2579 for (; !iter.done(); iter.next()) { 2580 int cur_index = iter.inner_class_info_index(); 2581 if (cur_index == 0) { 2582 continue; // JVM spec. allows null inner class refs so skip it 2583 } 2584 int new_index = find_new_index(cur_index); 2585 if (new_index != 0) { 2586 RC_TRACE_WITH_THREAD(0x00080000, THREAD, 2587 ("inner_class_info change: %d to %d", cur_index, new_index)); 2588 iter.set_inner_class_info_index(new_index); 2589 } 2590 cur_index = iter.outer_class_info_index(); 2591 new_index = find_new_index(cur_index); 2592 if (new_index != 0) { 2593 RC_TRACE_WITH_THREAD(0x00080000, THREAD, 2594 ("outer_class_info change: %d to %d", cur_index, new_index)); 2595 iter.set_outer_class_info_index(new_index); 2596 } 2597 cur_index = iter.inner_name_index(); 2598 new_index = find_new_index(cur_index); 2599 if (new_index != 0) { 2600 RC_TRACE_WITH_THREAD(0x00080000, THREAD, 2601 ("inner_name change: %d to %d", cur_index, new_index)); 2602 iter.set_inner_name_index(new_index); 2603 } 2604 } // end for each inner class 2605 2606 // Attach each method in klass to the new constant pool and update 2607 // to use new constant pool indices as needed: 2608 Array<Method*>* methods = scratch_class->methods(); 2609 for (i = methods->length() - 1; i >= 0; i--) { 2610 methodHandle method(THREAD, methods->at(i)); 2611 method->set_constants(scratch_cp()); 2612 2613 int new_index = find_new_index(method->name_index()); 2614 if (new_index != 0) { 2615 RC_TRACE_WITH_THREAD(0x00080000, THREAD, 2616 ("method-name_index change: %d to %d", method->name_index(), 2617 new_index)); 2618 method->set_name_index(new_index); 2619 } 2620 new_index = find_new_index(method->signature_index()); 2621 if (new_index != 0) { 2622 RC_TRACE_WITH_THREAD(0x00080000, THREAD, 2623 ("method-signature_index change: %d to %d", 2624 method->signature_index(), new_index)); 2625 method->set_signature_index(new_index); 2626 } 2627 new_index = find_new_index(method->generic_signature_index()); 2628 if (new_index != 0) { 2629 RC_TRACE_WITH_THREAD(0x00080000, THREAD, 2630 ("method-generic_signature_index change: %d to %d", 2631 method->generic_signature_index(), new_index)); 2632 method->set_generic_signature_index(new_index); 2633 } 2634 2635 // Update constant pool indices in the method's checked exception 2636 // table to use new constant indices as needed. 2637 int cext_length = method->checked_exceptions_length(); 2638 if (cext_length > 0) { 2639 CheckedExceptionElement * cext_table = 2640 method->checked_exceptions_start(); 2641 for (int j = 0; j < cext_length; j++) { 2642 int cur_index = cext_table[j].class_cp_index; 2643 int new_index = find_new_index(cur_index); 2644 if (new_index != 0) { 2645 RC_TRACE_WITH_THREAD(0x00080000, THREAD, 2646 ("cext-class_cp_index change: %d to %d", cur_index, new_index)); 2647 cext_table[j].class_cp_index = (u2)new_index; 2648 } 2649 } // end for each checked exception table entry 2650 } // end if there are checked exception table entries 2651 2652 // Update each catch type index in the method's exception table 2653 // to use new constant pool indices as needed. The exception table 2654 // holds quadruple entries of the form: 2655 // (beg_bci, end_bci, handler_bci, klass_index) 2656 2657 ExceptionTable ex_table(method()); 2658 int ext_length = ex_table.length(); 2659 2660 for (int j = 0; j < ext_length; j ++) { 2661 int cur_index = ex_table.catch_type_index(j); 2662 int new_index = find_new_index(cur_index); 2663 if (new_index != 0) { 2664 RC_TRACE_WITH_THREAD(0x00080000, THREAD, 2665 ("ext-klass_index change: %d to %d", cur_index, new_index)); 2666 ex_table.set_catch_type_index(j, new_index); 2667 } 2668 } // end for each exception table entry 2669 2670 // Update constant pool indices in the method's local variable 2671 // table to use new constant indices as needed. The local variable 2672 // table hold sextuple entries of the form: 2673 // (start_pc, length, name_index, descriptor_index, signature_index, slot) 2674 int lvt_length = method->localvariable_table_length(); 2675 if (lvt_length > 0) { 2676 LocalVariableTableElement * lv_table = 2677 method->localvariable_table_start(); 2678 for (int j = 0; j < lvt_length; j++) { 2679 int cur_index = lv_table[j].name_cp_index; 2680 int new_index = find_new_index(cur_index); 2681 if (new_index != 0) { 2682 RC_TRACE_WITH_THREAD(0x00080000, THREAD, 2683 ("lvt-name_cp_index change: %d to %d", cur_index, new_index)); 2684 lv_table[j].name_cp_index = (u2)new_index; 2685 } 2686 cur_index = lv_table[j].descriptor_cp_index; 2687 new_index = find_new_index(cur_index); 2688 if (new_index != 0) { 2689 RC_TRACE_WITH_THREAD(0x00080000, THREAD, 2690 ("lvt-descriptor_cp_index change: %d to %d", cur_index, 2691 new_index)); 2692 lv_table[j].descriptor_cp_index = (u2)new_index; 2693 } 2694 cur_index = lv_table[j].signature_cp_index; 2695 new_index = find_new_index(cur_index); 2696 if (new_index != 0) { 2697 RC_TRACE_WITH_THREAD(0x00080000, THREAD, 2698 ("lvt-signature_cp_index change: %d to %d", cur_index, new_index)); 2699 lv_table[j].signature_cp_index = (u2)new_index; 2700 } 2701 } // end for each local variable table entry 2702 } // end if there are local variable table entries 2703 2704 rewrite_cp_refs_in_stack_map_table(method, THREAD); 2705 } // end for each method 2706 } // end set_new_constant_pool() 2707 2708 2709 // Unevolving classes may point to methods of the_class directly 2710 // from their constant pool caches, itables, and/or vtables. We 2711 // use the ClassLoaderDataGraph::classes_do() facility and this helper 2712 // to fix up these pointers. 2713 2714 // Adjust cpools and vtables closure 2715 void VM_RedefineClasses::AdjustCpoolCacheAndVtable::do_klass(Klass* k) { 2716 2717 // This is a very busy routine. We don't want too much tracing 2718 // printed out. 2719 bool trace_name_printed = false; 2720 2721 // Very noisy: only enable this call if you are trying to determine 2722 // that a specific class gets found by this routine. 2723 // RC_TRACE macro has an embedded ResourceMark 2724 // RC_TRACE_WITH_THREAD(0x00100000, THREAD, 2725 // ("adjust check: name=%s", k->external_name())); 2726 // trace_name_printed = true; 2727 2728 // If the class being redefined is java.lang.Object, we need to fix all 2729 // array class vtables also 2730 if (k->oop_is_array() && _the_class_oop == SystemDictionary::Object_klass()) { 2731 k->vtable()->adjust_method_entries(_matching_old_methods, 2732 _matching_new_methods, 2733 _matching_methods_length, 2734 &trace_name_printed); 2735 } else if (k->oop_is_instance()) { 2736 HandleMark hm(_thread); 2737 InstanceKlass *ik = InstanceKlass::cast(k); 2738 2739 // HotSpot specific optimization! HotSpot does not currently 2740 // support delegation from the bootstrap class loader to a 2741 // user-defined class loader. This means that if the bootstrap 2742 // class loader is the initiating class loader, then it will also 2743 // be the defining class loader. This also means that classes 2744 // loaded by the bootstrap class loader cannot refer to classes 2745 // loaded by a user-defined class loader. Note: a user-defined 2746 // class loader can delegate to the bootstrap class loader. 2747 // 2748 // If the current class being redefined has a user-defined class 2749 // loader as its defining class loader, then we can skip all 2750 // classes loaded by the bootstrap class loader. 2751 bool is_user_defined = 2752 InstanceKlass::cast(_the_class_oop)->class_loader() != NULL; 2753 if (is_user_defined && ik->class_loader() == NULL) { 2754 return; 2755 } 2756 2757 // Fix the vtable embedded in the_class and subclasses of the_class, 2758 // if one exists. We discard scratch_class and we don't keep an 2759 // InstanceKlass around to hold obsolete methods so we don't have 2760 // any other InstanceKlass embedded vtables to update. The vtable 2761 // holds the Method*s for virtual (but not final) methods. 2762 // Default methods, or concrete methods in interfaces are stored 2763 // in the vtable, so if an interface changes we need to check 2764 // adjust_method_entries() for every InstanceKlass, which will also 2765 // adjust the default method vtable indices. 2766 // We also need to adjust any default method entries that are 2767 // not yet in the vtable, because the vtable setup is in progress. 2768 // This must be done after we adjust the default_methods and 2769 // default_vtable_indices for methods already in the vtable. 2770 if (ik->vtable_length() > 0 && (_the_class_oop->is_interface() 2771 || ik->is_subtype_of(_the_class_oop))) { 2772 // ik->vtable() creates a wrapper object; rm cleans it up 2773 ResourceMark rm(_thread); 2774 ik->vtable()->adjust_method_entries(_matching_old_methods, 2775 _matching_new_methods, 2776 _matching_methods_length, 2777 &trace_name_printed); 2778 ik->adjust_default_methods(_matching_old_methods, 2779 _matching_new_methods, 2780 _matching_methods_length, 2781 &trace_name_printed); 2782 } 2783 2784 // If the current class has an itable and we are either redefining an 2785 // interface or if the current class is a subclass of the_class, then 2786 // we potentially have to fix the itable. If we are redefining an 2787 // interface, then we have to call adjust_method_entries() for 2788 // every InstanceKlass that has an itable since there isn't a 2789 // subclass relationship between an interface and an InstanceKlass. 2790 if (ik->itable_length() > 0 && (_the_class_oop->is_interface() 2791 || ik->is_subclass_of(_the_class_oop))) { 2792 // ik->itable() creates a wrapper object; rm cleans it up 2793 ResourceMark rm(_thread); 2794 ik->itable()->adjust_method_entries(_matching_old_methods, 2795 _matching_new_methods, 2796 _matching_methods_length, 2797 &trace_name_printed); 2798 } 2799 2800 // The constant pools in other classes (other_cp) can refer to 2801 // methods in the_class. We have to update method information in 2802 // other_cp's cache. If other_cp has a previous version, then we 2803 // have to repeat the process for each previous version. The 2804 // constant pool cache holds the Method*s for non-virtual 2805 // methods and for virtual, final methods. 2806 // 2807 // Special case: if the current class is the_class, then new_cp 2808 // has already been attached to the_class and old_cp has already 2809 // been added as a previous version. The new_cp doesn't have any 2810 // cached references to old methods so it doesn't need to be 2811 // updated. We can simply start with the previous version(s) in 2812 // that case. 2813 constantPoolHandle other_cp; 2814 ConstantPoolCache* cp_cache; 2815 2816 if (ik != _the_class_oop) { 2817 // this klass' constant pool cache may need adjustment 2818 other_cp = constantPoolHandle(ik->constants()); 2819 cp_cache = other_cp->cache(); 2820 if (cp_cache != NULL) { 2821 cp_cache->adjust_method_entries(_matching_old_methods, 2822 _matching_new_methods, 2823 _matching_methods_length, 2824 &trace_name_printed); 2825 } 2826 } 2827 2828 // the previous versions' constant pool caches may need adjustment 2829 for (InstanceKlass* pv_node = ik->previous_versions(); 2830 pv_node != NULL; 2831 pv_node = pv_node->previous_versions()) { 2832 cp_cache = pv_node->constants()->cache(); 2833 if (cp_cache != NULL) { 2834 cp_cache->adjust_method_entries(_matching_old_methods, 2835 _matching_new_methods, 2836 _matching_methods_length, 2837 &trace_name_printed); 2838 } 2839 } 2840 } 2841 } 2842 2843 void VM_RedefineClasses::update_jmethod_ids() { 2844 for (int j = 0; j < _matching_methods_length; ++j) { 2845 Method* old_method = _matching_old_methods[j]; 2846 jmethodID jmid = old_method->find_jmethod_id_or_null(); 2847 if (jmid != NULL) { 2848 // There is a jmethodID, change it to point to the new method 2849 methodHandle new_method_h(_matching_new_methods[j]); 2850 Method::change_method_associated_with_jmethod_id(jmid, new_method_h()); 2851 assert(Method::resolve_jmethod_id(jmid) == _matching_new_methods[j], 2852 "should be replaced"); 2853 } 2854 } 2855 } 2856 2857 int VM_RedefineClasses::check_methods_and_mark_as_obsolete() { 2858 int emcp_method_count = 0; 2859 int obsolete_count = 0; 2860 int old_index = 0; 2861 for (int j = 0; j < _matching_methods_length; ++j, ++old_index) { 2862 Method* old_method = _matching_old_methods[j]; 2863 Method* new_method = _matching_new_methods[j]; 2864 Method* old_array_method; 2865 2866 // Maintain an old_index into the _old_methods array by skipping 2867 // deleted methods 2868 while ((old_array_method = _old_methods->at(old_index)) != old_method) { 2869 ++old_index; 2870 } 2871 2872 if (MethodComparator::methods_EMCP(old_method, new_method)) { 2873 // The EMCP definition from JSR-163 requires the bytecodes to be 2874 // the same with the exception of constant pool indices which may 2875 // differ. However, the constants referred to by those indices 2876 // must be the same. 2877 // 2878 // We use methods_EMCP() for comparison since constant pool 2879 // merging can remove duplicate constant pool entries that were 2880 // present in the old method and removed from the rewritten new 2881 // method. A faster binary comparison function would consider the 2882 // old and new methods to be different when they are actually 2883 // EMCP. 2884 // 2885 // The old and new methods are EMCP and you would think that we 2886 // could get rid of one of them here and now and save some space. 2887 // However, the concept of EMCP only considers the bytecodes and 2888 // the constant pool entries in the comparison. Other things, 2889 // e.g., the line number table (LNT) or the local variable table 2890 // (LVT) don't count in the comparison. So the new (and EMCP) 2891 // method can have a new LNT that we need so we can't just 2892 // overwrite the new method with the old method. 2893 // 2894 // When this routine is called, we have already attached the new 2895 // methods to the_class so the old methods are effectively 2896 // overwritten. However, if an old method is still executing, 2897 // then the old method cannot be collected until sometime after 2898 // the old method call has returned. So the overwriting of old 2899 // methods by new methods will save us space except for those 2900 // (hopefully few) old methods that are still executing. 2901 // 2902 // A method refers to a ConstMethod* and this presents another 2903 // possible avenue to space savings. The ConstMethod* in the 2904 // new method contains possibly new attributes (LNT, LVT, etc). 2905 // At first glance, it seems possible to save space by replacing 2906 // the ConstMethod* in the old method with the ConstMethod* 2907 // from the new method. The old and new methods would share the 2908 // same ConstMethod* and we would save the space occupied by 2909 // the old ConstMethod*. However, the ConstMethod* contains 2910 // a back reference to the containing method. Sharing the 2911 // ConstMethod* between two methods could lead to confusion in 2912 // the code that uses the back reference. This would lead to 2913 // brittle code that could be broken in non-obvious ways now or 2914 // in the future. 2915 // 2916 // Another possibility is to copy the ConstMethod* from the new 2917 // method to the old method and then overwrite the new method with 2918 // the old method. Since the ConstMethod* contains the bytecodes 2919 // for the method embedded in the oop, this option would change 2920 // the bytecodes out from under any threads executing the old 2921 // method and make the thread's bcp invalid. Since EMCP requires 2922 // that the bytecodes be the same modulo constant pool indices, it 2923 // is straight forward to compute the correct new bcp in the new 2924 // ConstMethod* from the old bcp in the old ConstMethod*. The 2925 // time consuming part would be searching all the frames in all 2926 // of the threads to find all of the calls to the old method. 2927 // 2928 // It looks like we will have to live with the limited savings 2929 // that we get from effectively overwriting the old methods 2930 // when the new methods are attached to the_class. 2931 2932 // Count number of methods that are EMCP. The method will be marked 2933 // old but not obsolete if it is EMCP. 2934 emcp_method_count++; 2935 2936 // An EMCP method is _not_ obsolete. An obsolete method has a 2937 // different jmethodID than the current method. An EMCP method 2938 // has the same jmethodID as the current method. Having the 2939 // same jmethodID for all EMCP versions of a method allows for 2940 // a consistent view of the EMCP methods regardless of which 2941 // EMCP method you happen to have in hand. For example, a 2942 // breakpoint set in one EMCP method will work for all EMCP 2943 // versions of the method including the current one. 2944 } else { 2945 // mark obsolete methods as such 2946 old_method->set_is_obsolete(); 2947 obsolete_count++; 2948 2949 // obsolete methods need a unique idnum so they become new entries in 2950 // the jmethodID cache in InstanceKlass 2951 u2 num = InstanceKlass::cast(_the_class_oop)->next_method_idnum(); 2952 if (num != ConstMethod::UNSET_IDNUM) { 2953 old_method->set_method_idnum(num); 2954 } 2955 2956 // With tracing we try not to "yack" too much. The position of 2957 // this trace assumes there are fewer obsolete methods than 2958 // EMCP methods. 2959 RC_TRACE(0x00000100, ("mark %s(%s) as obsolete", 2960 old_method->name()->as_C_string(), 2961 old_method->signature()->as_C_string())); 2962 } 2963 old_method->set_is_old(); 2964 } 2965 for (int i = 0; i < _deleted_methods_length; ++i) { 2966 Method* old_method = _deleted_methods[i]; 2967 2968 assert(!old_method->has_vtable_index(), 2969 "cannot delete methods with vtable entries");; 2970 2971 // Mark all deleted methods as old, obsolete and deleted 2972 old_method->set_is_deleted(); 2973 old_method->set_is_old(); 2974 old_method->set_is_obsolete(); 2975 ++obsolete_count; 2976 // With tracing we try not to "yack" too much. The position of 2977 // this trace assumes there are fewer obsolete methods than 2978 // EMCP methods. 2979 RC_TRACE(0x00000100, ("mark deleted %s(%s) as obsolete", 2980 old_method->name()->as_C_string(), 2981 old_method->signature()->as_C_string())); 2982 } 2983 assert((emcp_method_count + obsolete_count) == _old_methods->length(), 2984 "sanity check"); 2985 RC_TRACE(0x00000100, ("EMCP_cnt=%d, obsolete_cnt=%d", emcp_method_count, 2986 obsolete_count)); 2987 return emcp_method_count; 2988 } 2989 2990 // This internal class transfers the native function registration from old methods 2991 // to new methods. It is designed to handle both the simple case of unchanged 2992 // native methods and the complex cases of native method prefixes being added and/or 2993 // removed. 2994 // It expects only to be used during the VM_RedefineClasses op (a safepoint). 2995 // 2996 // This class is used after the new methods have been installed in "the_class". 2997 // 2998 // So, for example, the following must be handled. Where 'm' is a method and 2999 // a number followed by an underscore is a prefix. 3000 // 3001 // Old Name New Name 3002 // Simple transfer to new method m -> m 3003 // Add prefix m -> 1_m 3004 // Remove prefix 1_m -> m 3005 // Simultaneous add of prefixes m -> 3_2_1_m 3006 // Simultaneous removal of prefixes 3_2_1_m -> m 3007 // Simultaneous add and remove 1_m -> 2_m 3008 // Same, caused by prefix removal only 3_2_1_m -> 3_2_m 3009 // 3010 class TransferNativeFunctionRegistration { 3011 private: 3012 instanceKlassHandle the_class; 3013 int prefix_count; 3014 char** prefixes; 3015 3016 // Recursively search the binary tree of possibly prefixed method names. 3017 // Iteration could be used if all agents were well behaved. Full tree walk is 3018 // more resilent to agents not cleaning up intermediate methods. 3019 // Branch at each depth in the binary tree is: 3020 // (1) without the prefix. 3021 // (2) with the prefix. 3022 // where 'prefix' is the prefix at that 'depth' (first prefix, second prefix,...) 3023 Method* search_prefix_name_space(int depth, char* name_str, size_t name_len, 3024 Symbol* signature) { 3025 TempNewSymbol name_symbol = SymbolTable::probe(name_str, (int)name_len); 3026 if (name_symbol != NULL) { 3027 Method* method = the_class()->lookup_method(name_symbol, signature); 3028 if (method != NULL) { 3029 // Even if prefixed, intermediate methods must exist. 3030 if (method->is_native()) { 3031 // Wahoo, we found a (possibly prefixed) version of the method, return it. 3032 return method; 3033 } 3034 if (depth < prefix_count) { 3035 // Try applying further prefixes (other than this one). 3036 method = search_prefix_name_space(depth+1, name_str, name_len, signature); 3037 if (method != NULL) { 3038 return method; // found 3039 } 3040 3041 // Try adding this prefix to the method name and see if it matches 3042 // another method name. 3043 char* prefix = prefixes[depth]; 3044 size_t prefix_len = strlen(prefix); 3045 size_t trial_len = name_len + prefix_len; 3046 char* trial_name_str = NEW_RESOURCE_ARRAY(char, trial_len + 1); 3047 strcpy(trial_name_str, prefix); 3048 strcat(trial_name_str, name_str); 3049 method = search_prefix_name_space(depth+1, trial_name_str, trial_len, 3050 signature); 3051 if (method != NULL) { 3052 // If found along this branch, it was prefixed, mark as such 3053 method->set_is_prefixed_native(); 3054 return method; // found 3055 } 3056 } 3057 } 3058 } 3059 return NULL; // This whole branch bore nothing 3060 } 3061 3062 // Return the method name with old prefixes stripped away. 3063 char* method_name_without_prefixes(Method* method) { 3064 Symbol* name = method->name(); 3065 char* name_str = name->as_utf8(); 3066 3067 // Old prefixing may be defunct, strip prefixes, if any. 3068 for (int i = prefix_count-1; i >= 0; i--) { 3069 char* prefix = prefixes[i]; 3070 size_t prefix_len = strlen(prefix); 3071 if (strncmp(prefix, name_str, prefix_len) == 0) { 3072 name_str += prefix_len; 3073 } 3074 } 3075 return name_str; 3076 } 3077 3078 // Strip any prefixes off the old native method, then try to find a 3079 // (possibly prefixed) new native that matches it. 3080 Method* strip_and_search_for_new_native(Method* method) { 3081 ResourceMark rm; 3082 char* name_str = method_name_without_prefixes(method); 3083 return search_prefix_name_space(0, name_str, strlen(name_str), 3084 method->signature()); 3085 } 3086 3087 public: 3088 3089 // Construct a native method transfer processor for this class. 3090 TransferNativeFunctionRegistration(instanceKlassHandle _the_class) { 3091 assert(SafepointSynchronize::is_at_safepoint(), "sanity check"); 3092 3093 the_class = _the_class; 3094 prefixes = JvmtiExport::get_all_native_method_prefixes(&prefix_count); 3095 } 3096 3097 // Attempt to transfer any of the old or deleted methods that are native 3098 void transfer_registrations(Method** old_methods, int methods_length) { 3099 for (int j = 0; j < methods_length; j++) { 3100 Method* old_method = old_methods[j]; 3101 3102 if (old_method->is_native() && old_method->has_native_function()) { 3103 Method* new_method = strip_and_search_for_new_native(old_method); 3104 if (new_method != NULL) { 3105 // Actually set the native function in the new method. 3106 // Redefine does not send events (except CFLH), certainly not this 3107 // behind the scenes re-registration. 3108 new_method->set_native_function(old_method->native_function(), 3109 !Method::native_bind_event_is_interesting); 3110 } 3111 } 3112 } 3113 } 3114 }; 3115 3116 // Don't lose the association between a native method and its JNI function. 3117 void VM_RedefineClasses::transfer_old_native_function_registrations(instanceKlassHandle the_class) { 3118 TransferNativeFunctionRegistration transfer(the_class); 3119 transfer.transfer_registrations(_deleted_methods, _deleted_methods_length); 3120 transfer.transfer_registrations(_matching_old_methods, _matching_methods_length); 3121 } 3122 3123 // Deoptimize all compiled code that depends on this class. 3124 // 3125 // If the can_redefine_classes capability is obtained in the onload 3126 // phase then the compiler has recorded all dependencies from startup. 3127 // In that case we need only deoptimize and throw away all compiled code 3128 // that depends on the class. 3129 // 3130 // If can_redefine_classes is obtained sometime after the onload 3131 // phase then the dependency information may be incomplete. In that case 3132 // the first call to RedefineClasses causes all compiled code to be 3133 // thrown away. As can_redefine_classes has been obtained then 3134 // all future compilations will record dependencies so second and 3135 // subsequent calls to RedefineClasses need only throw away code 3136 // that depends on the class. 3137 // 3138 void VM_RedefineClasses::flush_dependent_code(instanceKlassHandle k_h, TRAPS) { 3139 assert_locked_or_safepoint(Compile_lock); 3140 3141 // All dependencies have been recorded from startup or this is a second or 3142 // subsequent use of RedefineClasses 3143 if (JvmtiExport::all_dependencies_are_recorded()) { 3144 Universe::flush_evol_dependents_on(k_h); 3145 } else { 3146 CodeCache::mark_all_nmethods_for_deoptimization(); 3147 3148 ResourceMark rm(THREAD); 3149 DeoptimizationMarker dm; 3150 3151 // Deoptimize all activations depending on marked nmethods 3152 Deoptimization::deoptimize_dependents(); 3153 3154 // Make the dependent methods not entrant (in VM_Deoptimize they are made zombies) 3155 CodeCache::make_marked_nmethods_not_entrant(); 3156 3157 // From now on we know that the dependency information is complete 3158 JvmtiExport::set_all_dependencies_are_recorded(true); 3159 } 3160 } 3161 3162 void VM_RedefineClasses::compute_added_deleted_matching_methods() { 3163 Method* old_method; 3164 Method* new_method; 3165 3166 _matching_old_methods = NEW_RESOURCE_ARRAY(Method*, _old_methods->length()); 3167 _matching_new_methods = NEW_RESOURCE_ARRAY(Method*, _old_methods->length()); 3168 _added_methods = NEW_RESOURCE_ARRAY(Method*, _new_methods->length()); 3169 _deleted_methods = NEW_RESOURCE_ARRAY(Method*, _old_methods->length()); 3170 3171 _matching_methods_length = 0; 3172 _deleted_methods_length = 0; 3173 _added_methods_length = 0; 3174 3175 int nj = 0; 3176 int oj = 0; 3177 while (true) { 3178 if (oj >= _old_methods->length()) { 3179 if (nj >= _new_methods->length()) { 3180 break; // we've looked at everything, done 3181 } 3182 // New method at the end 3183 new_method = _new_methods->at(nj); 3184 _added_methods[_added_methods_length++] = new_method; 3185 ++nj; 3186 } else if (nj >= _new_methods->length()) { 3187 // Old method, at the end, is deleted 3188 old_method = _old_methods->at(oj); 3189 _deleted_methods[_deleted_methods_length++] = old_method; 3190 ++oj; 3191 } else { 3192 old_method = _old_methods->at(oj); 3193 new_method = _new_methods->at(nj); 3194 if (old_method->name() == new_method->name()) { 3195 if (old_method->signature() == new_method->signature()) { 3196 _matching_old_methods[_matching_methods_length ] = old_method; 3197 _matching_new_methods[_matching_methods_length++] = new_method; 3198 ++nj; 3199 ++oj; 3200 } else { 3201 // added overloaded have already been moved to the end, 3202 // so this is a deleted overloaded method 3203 _deleted_methods[_deleted_methods_length++] = old_method; 3204 ++oj; 3205 } 3206 } else { // names don't match 3207 if (old_method->name()->fast_compare(new_method->name()) > 0) { 3208 // new method 3209 _added_methods[_added_methods_length++] = new_method; 3210 ++nj; 3211 } else { 3212 // deleted method 3213 _deleted_methods[_deleted_methods_length++] = old_method; 3214 ++oj; 3215 } 3216 } 3217 } 3218 } 3219 assert(_matching_methods_length + _deleted_methods_length == _old_methods->length(), "sanity"); 3220 assert(_matching_methods_length + _added_methods_length == _new_methods->length(), "sanity"); 3221 } 3222 3223 3224 void VM_RedefineClasses::swap_annotations(instanceKlassHandle the_class, 3225 instanceKlassHandle scratch_class) { 3226 // Since there is currently no rewriting of type annotations indexes 3227 // into the CP, we null out type annotations on scratch_class before 3228 // we swap annotations with the_class rather than facing the 3229 // possibility of shipping annotations with broken indexes to 3230 // Java-land. 3231 ClassLoaderData* loader_data = scratch_class->class_loader_data(); 3232 AnnotationArray* new_class_type_annotations = scratch_class->class_type_annotations(); 3233 if (new_class_type_annotations != NULL) { 3234 MetadataFactory::free_array<u1>(loader_data, new_class_type_annotations); 3235 scratch_class->annotations()->set_class_type_annotations(NULL); 3236 } 3237 Array<AnnotationArray*>* new_field_type_annotations = scratch_class->fields_type_annotations(); 3238 if (new_field_type_annotations != NULL) { 3239 Annotations::free_contents(loader_data, new_field_type_annotations); 3240 scratch_class->annotations()->set_fields_type_annotations(NULL); 3241 } 3242 3243 // Swap annotation fields values 3244 Annotations* old_annotations = the_class->annotations(); 3245 the_class->set_annotations(scratch_class->annotations()); 3246 scratch_class->set_annotations(old_annotations); 3247 } 3248 3249 3250 // Install the redefinition of a class: 3251 // - house keeping (flushing breakpoints and caches, deoptimizing 3252 // dependent compiled code) 3253 // - replacing parts in the_class with parts from scratch_class 3254 // - adding a weak reference to track the obsolete but interesting 3255 // parts of the_class 3256 // - adjusting constant pool caches and vtables in other classes 3257 // that refer to methods in the_class. These adjustments use the 3258 // ClassLoaderDataGraph::classes_do() facility which only allows 3259 // a helper method to be specified. The interesting parameters 3260 // that we would like to pass to the helper method are saved in 3261 // static global fields in the VM operation. 3262 void VM_RedefineClasses::redefine_single_class(jclass the_jclass, 3263 Klass* scratch_class_oop, TRAPS) { 3264 3265 HandleMark hm(THREAD); // make sure handles from this call are freed 3266 RC_TIMER_START(_timer_rsc_phase1); 3267 3268 instanceKlassHandle scratch_class(scratch_class_oop); 3269 3270 oop the_class_mirror = JNIHandles::resolve_non_null(the_jclass); 3271 Klass* the_class_oop = java_lang_Class::as_Klass(the_class_mirror); 3272 instanceKlassHandle the_class = instanceKlassHandle(THREAD, the_class_oop); 3273 3274 // Remove all breakpoints in methods of this class 3275 JvmtiBreakpoints& jvmti_breakpoints = JvmtiCurrentBreakpoints::get_jvmti_breakpoints(); 3276 jvmti_breakpoints.clearall_in_class_at_safepoint(the_class_oop); 3277 3278 // Deoptimize all compiled code that depends on this class 3279 flush_dependent_code(the_class, THREAD); 3280 3281 _old_methods = the_class->methods(); 3282 _new_methods = scratch_class->methods(); 3283 _the_class_oop = the_class_oop; 3284 compute_added_deleted_matching_methods(); 3285 update_jmethod_ids(); 3286 3287 // Attach new constant pool to the original klass. The original 3288 // klass still refers to the old constant pool (for now). 3289 scratch_class->constants()->set_pool_holder(the_class()); 3290 3291 #if 0 3292 // In theory, with constant pool merging in place we should be able 3293 // to save space by using the new, merged constant pool in place of 3294 // the old constant pool(s). By "pool(s)" I mean the constant pool in 3295 // the klass version we are replacing now and any constant pool(s) in 3296 // previous versions of klass. Nice theory, doesn't work in practice. 3297 // When this code is enabled, even simple programs throw NullPointer 3298 // exceptions. I'm guessing that this is caused by some constant pool 3299 // cache difference between the new, merged constant pool and the 3300 // constant pool that was just being used by the klass. I'm keeping 3301 // this code around to archive the idea, but the code has to remain 3302 // disabled for now. 3303 3304 // Attach each old method to the new constant pool. This can be 3305 // done here since we are past the bytecode verification and 3306 // constant pool optimization phases. 3307 for (int i = _old_methods->length() - 1; i >= 0; i--) { 3308 Method* method = _old_methods->at(i); 3309 method->set_constants(scratch_class->constants()); 3310 } 3311 3312 { 3313 // walk all previous versions of the klass 3314 InstanceKlass *ik = (InstanceKlass *)the_class(); 3315 PreviousVersionWalker pvw(ik); 3316 instanceKlassHandle ikh; 3317 do { 3318 ikh = pvw.next_previous_version(); 3319 if (!ikh.is_null()) { 3320 ik = ikh(); 3321 3322 // attach previous version of klass to the new constant pool 3323 ik->set_constants(scratch_class->constants()); 3324 3325 // Attach each method in the previous version of klass to the 3326 // new constant pool 3327 Array<Method*>* prev_methods = ik->methods(); 3328 for (int i = prev_methods->length() - 1; i >= 0; i--) { 3329 Method* method = prev_methods->at(i); 3330 method->set_constants(scratch_class->constants()); 3331 } 3332 } 3333 } while (!ikh.is_null()); 3334 } 3335 #endif 3336 3337 // Replace methods and constantpool 3338 the_class->set_methods(_new_methods); 3339 scratch_class->set_methods(_old_methods); // To prevent potential GCing of the old methods, 3340 // and to be able to undo operation easily. 3341 3342 ConstantPool* old_constants = the_class->constants(); 3343 the_class->set_constants(scratch_class->constants()); 3344 scratch_class->set_constants(old_constants); // See the previous comment. 3345 #if 0 3346 // We are swapping the guts of "the new class" with the guts of "the 3347 // class". Since the old constant pool has just been attached to "the 3348 // new class", it seems logical to set the pool holder in the old 3349 // constant pool also. However, doing this will change the observable 3350 // class hierarchy for any old methods that are still executing. A 3351 // method can query the identity of its "holder" and this query uses 3352 // the method's constant pool link to find the holder. The change in 3353 // holding class from "the class" to "the new class" can confuse 3354 // things. 3355 // 3356 // Setting the old constant pool's holder will also cause 3357 // verification done during vtable initialization below to fail. 3358 // During vtable initialization, the vtable's class is verified to be 3359 // a subtype of the method's holder. The vtable's class is "the 3360 // class" and the method's holder is gotten from the constant pool 3361 // link in the method itself. For "the class"'s directly implemented 3362 // methods, the method holder is "the class" itself (as gotten from 3363 // the new constant pool). The check works fine in this case. The 3364 // check also works fine for methods inherited from super classes. 3365 // 3366 // Miranda methods are a little more complicated. A miranda method is 3367 // provided by an interface when the class implementing the interface 3368 // does not provide its own method. These interfaces are implemented 3369 // internally as an InstanceKlass. These special instanceKlasses 3370 // share the constant pool of the class that "implements" the 3371 // interface. By sharing the constant pool, the method holder of a 3372 // miranda method is the class that "implements" the interface. In a 3373 // non-redefine situation, the subtype check works fine. However, if 3374 // the old constant pool's pool holder is modified, then the check 3375 // fails because there is no class hierarchy relationship between the 3376 // vtable's class and "the new class". 3377 3378 old_constants->set_pool_holder(scratch_class()); 3379 #endif 3380 3381 // track number of methods that are EMCP for add_previous_version() call below 3382 int emcp_method_count = check_methods_and_mark_as_obsolete(); 3383 transfer_old_native_function_registrations(the_class); 3384 3385 // The class file bytes from before any retransformable agents mucked 3386 // with them was cached on the scratch class, move to the_class. 3387 // Note: we still want to do this if nothing needed caching since it 3388 // should get cleared in the_class too. 3389 if (the_class->get_cached_class_file_bytes() == 0) { 3390 // the_class doesn't have a cache yet so copy it 3391 the_class->set_cached_class_file(scratch_class->get_cached_class_file()); 3392 } 3393 #ifndef PRODUCT 3394 else { 3395 assert(the_class->get_cached_class_file_bytes() == 3396 scratch_class->get_cached_class_file_bytes(), "cache ptrs must match"); 3397 assert(the_class->get_cached_class_file_len() == 3398 scratch_class->get_cached_class_file_len(), "cache lens must match"); 3399 } 3400 #endif 3401 3402 // NULL out in scratch class to not delete twice. The class to be redefined 3403 // always owns these bytes. 3404 scratch_class->set_cached_class_file(NULL); 3405 3406 // Replace inner_classes 3407 Array<u2>* old_inner_classes = the_class->inner_classes(); 3408 the_class->set_inner_classes(scratch_class->inner_classes()); 3409 scratch_class->set_inner_classes(old_inner_classes); 3410 3411 // Initialize the vtable and interface table after 3412 // methods have been rewritten 3413 { 3414 ResourceMark rm(THREAD); 3415 // no exception should happen here since we explicitly 3416 // do not check loader constraints. 3417 // compare_and_normalize_class_versions has already checked: 3418 // - classloaders unchanged, signatures unchanged 3419 // - all instanceKlasses for redefined classes reused & contents updated 3420 the_class->vtable()->initialize_vtable(false, THREAD); 3421 the_class->itable()->initialize_itable(false, THREAD); 3422 assert(!HAS_PENDING_EXCEPTION || (THREAD->pending_exception()->is_a(SystemDictionary::ThreadDeath_klass())), "redefine exception"); 3423 } 3424 3425 // Leave arrays of jmethodIDs and itable index cache unchanged 3426 3427 // Copy the "source file name" attribute from new class version 3428 the_class->set_source_file_name_index( 3429 scratch_class->source_file_name_index()); 3430 3431 // Copy the "source debug extension" attribute from new class version 3432 the_class->set_source_debug_extension( 3433 scratch_class->source_debug_extension(), 3434 scratch_class->source_debug_extension() == NULL ? 0 : 3435 (int)strlen(scratch_class->source_debug_extension())); 3436 3437 // Use of javac -g could be different in the old and the new 3438 if (scratch_class->access_flags().has_localvariable_table() != 3439 the_class->access_flags().has_localvariable_table()) { 3440 3441 AccessFlags flags = the_class->access_flags(); 3442 if (scratch_class->access_flags().has_localvariable_table()) { 3443 flags.set_has_localvariable_table(); 3444 } else { 3445 flags.clear_has_localvariable_table(); 3446 } 3447 the_class->set_access_flags(flags); 3448 } 3449 3450 swap_annotations(the_class, scratch_class); 3451 3452 // Replace minor version number of class file 3453 u2 old_minor_version = the_class->minor_version(); 3454 the_class->set_minor_version(scratch_class->minor_version()); 3455 scratch_class->set_minor_version(old_minor_version); 3456 3457 // Replace major version number of class file 3458 u2 old_major_version = the_class->major_version(); 3459 the_class->set_major_version(scratch_class->major_version()); 3460 scratch_class->set_major_version(old_major_version); 3461 3462 // Replace CP indexes for class and name+type of enclosing method 3463 u2 old_class_idx = the_class->enclosing_method_class_index(); 3464 u2 old_method_idx = the_class->enclosing_method_method_index(); 3465 the_class->set_enclosing_method_indices( 3466 scratch_class->enclosing_method_class_index(), 3467 scratch_class->enclosing_method_method_index()); 3468 scratch_class->set_enclosing_method_indices(old_class_idx, old_method_idx); 3469 3470 the_class->set_has_been_redefined(); 3471 3472 // keep track of previous versions of this class 3473 the_class->add_previous_version(scratch_class, emcp_method_count); 3474 3475 RC_TIMER_STOP(_timer_rsc_phase1); 3476 RC_TIMER_START(_timer_rsc_phase2); 3477 3478 // Adjust constantpool caches and vtables for all classes 3479 // that reference methods of the evolved class. 3480 AdjustCpoolCacheAndVtable adjust_cpool_cache_and_vtable(THREAD); 3481 ClassLoaderDataGraph::classes_do(&adjust_cpool_cache_and_vtable); 3482 3483 // JSR-292 support 3484 { 3485 bool trace_name_printed = false; 3486 the_class->adjust_member_name_table(_matching_old_methods, _matching_new_methods, _matching_methods_length, &trace_name_printed); 3487 } 3488 3489 // Fix Resolution Error table also to remove old constant pools 3490 SystemDictionary::delete_resolution_error(old_constants); 3491 3492 if (the_class->oop_map_cache() != NULL) { 3493 // Flush references to any obsolete methods from the oop map cache 3494 // so that obsolete methods are not pinned. 3495 the_class->oop_map_cache()->flush_obsolete_entries(); 3496 } 3497 3498 // increment the classRedefinedCount field in the_class and in any 3499 // direct and indirect subclasses of the_class 3500 increment_class_counter((InstanceKlass *)the_class(), THREAD); 3501 3502 // RC_TRACE macro has an embedded ResourceMark 3503 RC_TRACE_WITH_THREAD(0x00000001, THREAD, 3504 ("redefined name=%s, count=%d (avail_mem=" UINT64_FORMAT "K)", 3505 the_class->external_name(), 3506 java_lang_Class::classRedefinedCount(the_class_mirror), 3507 os::available_memory() >> 10)); 3508 3509 RC_TIMER_STOP(_timer_rsc_phase2); 3510 } // end redefine_single_class() 3511 3512 3513 // Increment the classRedefinedCount field in the specific InstanceKlass 3514 // and in all direct and indirect subclasses. 3515 void VM_RedefineClasses::increment_class_counter(InstanceKlass *ik, TRAPS) { 3516 oop class_mirror = ik->java_mirror(); 3517 Klass* class_oop = java_lang_Class::as_Klass(class_mirror); 3518 int new_count = java_lang_Class::classRedefinedCount(class_mirror) + 1; 3519 java_lang_Class::set_classRedefinedCount(class_mirror, new_count); 3520 3521 if (class_oop != _the_class_oop) { 3522 // _the_class_oop count is printed at end of redefine_single_class() 3523 RC_TRACE_WITH_THREAD(0x00000008, THREAD, 3524 ("updated count in subclass=%s to %d", ik->external_name(), new_count)); 3525 } 3526 3527 for (Klass *subk = ik->subklass(); subk != NULL; 3528 subk = subk->next_sibling()) { 3529 if (subk->oop_is_instance()) { 3530 // Only update instanceKlasses 3531 InstanceKlass *subik = (InstanceKlass*)subk; 3532 // recursively do subclasses of the current subclass 3533 increment_class_counter(subik, THREAD); 3534 } 3535 } 3536 } 3537 3538 void VM_RedefineClasses::CheckClass::do_klass(Klass* k) { 3539 bool no_old_methods = true; // be optimistic 3540 3541 // Both array and instance classes have vtables. 3542 // a vtable should never contain old or obsolete methods 3543 ResourceMark rm(_thread); 3544 if (k->vtable_length() > 0 && 3545 !k->vtable()->check_no_old_or_obsolete_entries()) { 3546 if (RC_TRACE_ENABLED(0x00004000)) { 3547 RC_TRACE_WITH_THREAD(0x00004000, _thread, 3548 ("klassVtable::check_no_old_or_obsolete_entries failure" 3549 " -- OLD or OBSOLETE method found -- class: %s", 3550 k->signature_name())); 3551 k->vtable()->dump_vtable(); 3552 } 3553 no_old_methods = false; 3554 } 3555 3556 if (k->oop_is_instance()) { 3557 HandleMark hm(_thread); 3558 InstanceKlass *ik = InstanceKlass::cast(k); 3559 3560 // an itable should never contain old or obsolete methods 3561 if (ik->itable_length() > 0 && 3562 !ik->itable()->check_no_old_or_obsolete_entries()) { 3563 if (RC_TRACE_ENABLED(0x00004000)) { 3564 RC_TRACE_WITH_THREAD(0x00004000, _thread, 3565 ("klassItable::check_no_old_or_obsolete_entries failure" 3566 " -- OLD or OBSOLETE method found -- class: %s", 3567 ik->signature_name())); 3568 ik->itable()->dump_itable(); 3569 } 3570 no_old_methods = false; 3571 } 3572 3573 // the constant pool cache should never contain non-deleted old or obsolete methods 3574 if (ik->constants() != NULL && 3575 ik->constants()->cache() != NULL && 3576 !ik->constants()->cache()->check_no_old_or_obsolete_entries()) { 3577 if (RC_TRACE_ENABLED(0x00004000)) { 3578 RC_TRACE_WITH_THREAD(0x00004000, _thread, 3579 ("cp-cache::check_no_old_or_obsolete_entries failure" 3580 " -- OLD or OBSOLETE method found -- class: %s", 3581 ik->signature_name())); 3582 ik->constants()->cache()->dump_cache(); 3583 } 3584 no_old_methods = false; 3585 } 3586 } 3587 3588 // print and fail guarantee if old methods are found. 3589 if (!no_old_methods) { 3590 if (RC_TRACE_ENABLED(0x00004000)) { 3591 dump_methods(); 3592 } else { 3593 tty->print_cr("INFO: use the '-XX:TraceRedefineClasses=16384' option " 3594 "to see more info about the following guarantee() failure."); 3595 } 3596 guarantee(false, "OLD and/or OBSOLETE method(s) found"); 3597 } 3598 } 3599 3600 3601 void VM_RedefineClasses::dump_methods() { 3602 int j; 3603 RC_TRACE(0x00004000, ("_old_methods --")); 3604 for (j = 0; j < _old_methods->length(); ++j) { 3605 Method* m = _old_methods->at(j); 3606 RC_TRACE_NO_CR(0x00004000, ("%4d (%5d) ", j, m->vtable_index())); 3607 m->access_flags().print_on(tty); 3608 tty->print(" -- "); 3609 m->print_name(tty); 3610 tty->cr(); 3611 } 3612 RC_TRACE(0x00004000, ("_new_methods --")); 3613 for (j = 0; j < _new_methods->length(); ++j) { 3614 Method* m = _new_methods->at(j); 3615 RC_TRACE_NO_CR(0x00004000, ("%4d (%5d) ", j, m->vtable_index())); 3616 m->access_flags().print_on(tty); 3617 tty->print(" -- "); 3618 m->print_name(tty); 3619 tty->cr(); 3620 } 3621 RC_TRACE(0x00004000, ("_matching_(old/new)_methods --")); 3622 for (j = 0; j < _matching_methods_length; ++j) { 3623 Method* m = _matching_old_methods[j]; 3624 RC_TRACE_NO_CR(0x00004000, ("%4d (%5d) ", j, m->vtable_index())); 3625 m->access_flags().print_on(tty); 3626 tty->print(" -- "); 3627 m->print_name(tty); 3628 tty->cr(); 3629 m = _matching_new_methods[j]; 3630 RC_TRACE_NO_CR(0x00004000, (" (%5d) ", m->vtable_index())); 3631 m->access_flags().print_on(tty); 3632 tty->cr(); 3633 } 3634 RC_TRACE(0x00004000, ("_deleted_methods --")); 3635 for (j = 0; j < _deleted_methods_length; ++j) { 3636 Method* m = _deleted_methods[j]; 3637 RC_TRACE_NO_CR(0x00004000, ("%4d (%5d) ", j, m->vtable_index())); 3638 m->access_flags().print_on(tty); 3639 tty->print(" -- "); 3640 m->print_name(tty); 3641 tty->cr(); 3642 } 3643 RC_TRACE(0x00004000, ("_added_methods --")); 3644 for (j = 0; j < _added_methods_length; ++j) { 3645 Method* m = _added_methods[j]; 3646 RC_TRACE_NO_CR(0x00004000, ("%4d (%5d) ", j, m->vtable_index())); 3647 m->access_flags().print_on(tty); 3648 tty->print(" -- "); 3649 m->print_name(tty); 3650 tty->cr(); 3651 } 3652 }