1 /*
2 * Copyright (c) 2003, 2024, 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 "cds/cdsConfig.hpp"
27 #include "cds/metaspaceShared.hpp"
28 #include "classfile/classFileStream.hpp"
29 #include "classfile/classLoaderDataGraph.hpp"
30 #include "classfile/classLoadInfo.hpp"
31 #include "classfile/javaClasses.inline.hpp"
32 #include "classfile/metadataOnStackMark.hpp"
33 #include "classfile/symbolTable.hpp"
34 #include "classfile/klassFactory.hpp"
35 #include "classfile/verifier.hpp"
36 #include "classfile/vmClasses.hpp"
37 #include "classfile/vmSymbols.hpp"
38 #include "code/codeCache.hpp"
39 #include "compiler/compileBroker.hpp"
40 #include "interpreter/oopMapCache.hpp"
41 #include "interpreter/rewriter.hpp"
42 #include "jfr/jfrEvents.hpp"
43 #include "logging/logStream.hpp"
44 #include "memory/metadataFactory.hpp"
45 #include "memory/resourceArea.hpp"
46 #include "memory/universe.hpp"
47 #include "oops/annotations.hpp"
48 #include "oops/constantPool.hpp"
49 #include "oops/fieldStreams.inline.hpp"
50 #include "oops/klass.inline.hpp"
51 #include "oops/klassVtable.hpp"
52 #include "oops/method.hpp"
53 #include "oops/oop.inline.hpp"
54 #include "oops/recordComponent.hpp"
55 #include "prims/jvmtiImpl.hpp"
56 #include "prims/jvmtiRedefineClasses.hpp"
57 #include "prims/jvmtiThreadState.inline.hpp"
58 #include "prims/resolvedMethodTable.hpp"
59 #include "prims/methodComparator.hpp"
60 #include "runtime/atomic.hpp"
61 #include "runtime/deoptimization.hpp"
62 #include "runtime/handles.inline.hpp"
63 #include "runtime/jniHandles.inline.hpp"
64 #include "runtime/relocator.hpp"
65 #include "runtime/safepointVerifiers.hpp"
66 #include "utilities/bitMap.inline.hpp"
67 #include "utilities/checkedCast.hpp"
68 #include "utilities/events.hpp"
69 #include "utilities/macros.hpp"
70
71 Array<Method*>* VM_RedefineClasses::_old_methods = nullptr;
72 Array<Method*>* VM_RedefineClasses::_new_methods = nullptr;
73 Method** VM_RedefineClasses::_matching_old_methods = nullptr;
74 Method** VM_RedefineClasses::_matching_new_methods = nullptr;
75 Method** VM_RedefineClasses::_deleted_methods = nullptr;
76 Method** VM_RedefineClasses::_added_methods = nullptr;
77 int VM_RedefineClasses::_matching_methods_length = 0;
78 int VM_RedefineClasses::_deleted_methods_length = 0;
79 int VM_RedefineClasses::_added_methods_length = 0;
80
81 // This flag is global as the constructor does not reset it:
82 bool VM_RedefineClasses::_has_redefined_Object = false;
83 u8 VM_RedefineClasses::_id_counter = 0;
84
85 VM_RedefineClasses::VM_RedefineClasses(jint class_count,
86 const jvmtiClassDefinition *class_defs,
87 JvmtiClassLoadKind class_load_kind) {
88 _class_count = class_count;
89 _class_defs = class_defs;
90 _class_load_kind = class_load_kind;
91 _any_class_has_resolved_methods = false;
92 _res = JVMTI_ERROR_NONE;
93 _the_class = nullptr;
94 _id = next_id();
95 }
96
97 static inline InstanceKlass* get_ik(jclass def) {
98 oop mirror = JNIHandles::resolve_non_null(def);
99 return InstanceKlass::cast(java_lang_Class::as_Klass(mirror));
100 }
101
102 // If any of the classes are being redefined, wait
103 // Parallel constant pool merging leads to indeterminate constant pools.
104 void VM_RedefineClasses::lock_classes() {
105 JvmtiThreadState *state = JvmtiThreadState::state_for(JavaThread::current());
106 GrowableArray<Klass*>* redef_classes = state->get_classes_being_redefined();
107
108 MonitorLocker ml(RedefineClasses_lock);
109
110 if (redef_classes == nullptr) {
111 redef_classes = new (mtClass) GrowableArray<Klass*>(1, mtClass);
112 state->set_classes_being_redefined(redef_classes);
113 }
114
115 bool has_redefined;
116 do {
117 has_redefined = false;
118 // Go through classes each time until none are being redefined. Skip
119 // the ones that are being redefined by this thread currently. Class file
120 // load hook event may trigger new class redefine when we are redefining
121 // a class (after lock_classes()).
122 for (int i = 0; i < _class_count; i++) {
123 InstanceKlass* ik = get_ik(_class_defs[i].klass);
124 // Check if we are currently redefining the class in this thread already.
125 if (redef_classes->contains(ik)) {
126 assert(ik->is_being_redefined(), "sanity");
127 } else {
128 if (ik->is_being_redefined()) {
129 ml.wait();
130 has_redefined = true;
131 break; // for loop
132 }
133 }
134 }
135 } while (has_redefined);
136
137 for (int i = 0; i < _class_count; i++) {
138 InstanceKlass* ik = get_ik(_class_defs[i].klass);
139 redef_classes->push(ik); // Add to the _classes_being_redefined list
140 ik->set_is_being_redefined(true);
141 }
142 ml.notify_all();
143 }
144
145 void VM_RedefineClasses::unlock_classes() {
146 JvmtiThreadState *state = JvmtiThreadState::state_for(JavaThread::current());
147 GrowableArray<Klass*>* redef_classes = state->get_classes_being_redefined();
148 assert(redef_classes != nullptr, "_classes_being_redefined is not allocated");
149
150 MonitorLocker ml(RedefineClasses_lock);
151
152 for (int i = _class_count - 1; i >= 0; i--) {
153 InstanceKlass* def_ik = get_ik(_class_defs[i].klass);
154 if (redef_classes->length() > 0) {
155 // Remove the class from _classes_being_redefined list
156 Klass* k = redef_classes->pop();
157 assert(def_ik == k, "unlocking wrong class");
158 }
159 assert(def_ik->is_being_redefined(),
160 "should be being redefined to get here");
161
162 // Unlock after we finish all redefines for this class within
163 // the thread. Same class can be pushed to the list multiple
164 // times (not more than once by each recursive redefinition).
165 if (!redef_classes->contains(def_ik)) {
166 def_ik->set_is_being_redefined(false);
167 }
168 }
169 ml.notify_all();
170 }
171
172 bool VM_RedefineClasses::doit_prologue() {
173 if (_class_count == 0) {
174 _res = JVMTI_ERROR_NONE;
175 return false;
176 }
177 if (_class_defs == nullptr) {
178 _res = JVMTI_ERROR_NULL_POINTER;
179 return false;
180 }
181
182 for (int i = 0; i < _class_count; i++) {
183 if (_class_defs[i].klass == nullptr) {
184 _res = JVMTI_ERROR_INVALID_CLASS;
185 return false;
186 }
187 if (_class_defs[i].class_byte_count == 0) {
188 _res = JVMTI_ERROR_INVALID_CLASS_FORMAT;
189 return false;
190 }
191 if (_class_defs[i].class_bytes == nullptr) {
192 _res = JVMTI_ERROR_NULL_POINTER;
193 return false;
194 }
195
196 oop mirror = JNIHandles::resolve_non_null(_class_defs[i].klass);
197 // classes for primitives, arrays, and hidden classes
198 // cannot be redefined.
199 if (!is_modifiable_class(mirror)) {
200 _res = JVMTI_ERROR_UNMODIFIABLE_CLASS;
201 return false;
202 }
203 }
204
205 // Start timer after all the sanity checks; not quite accurate, but
206 // better than adding a bunch of stop() calls.
207 if (log_is_enabled(Info, redefine, class, timer)) {
208 _timer_vm_op_prologue.start();
209 }
210
211 lock_classes();
212 // We first load new class versions in the prologue, because somewhere down the
213 // call chain it is required that the current thread is a Java thread.
214 _res = load_new_class_versions();
215 if (_res != JVMTI_ERROR_NONE) {
216 // free any successfully created classes, since none are redefined
217 for (int i = 0; i < _class_count; i++) {
218 if (_scratch_classes[i] != nullptr) {
219 ClassLoaderData* cld = _scratch_classes[i]->class_loader_data();
220 // Free the memory for this class at class unloading time. Not before
221 // because CMS might think this is still live.
222 InstanceKlass* ik = get_ik(_class_defs[i].klass);
223 if (ik->get_cached_class_file() == _scratch_classes[i]->get_cached_class_file()) {
224 // Don't double-free cached_class_file copied from the original class if error.
225 _scratch_classes[i]->set_cached_class_file(nullptr);
226 }
227 cld->add_to_deallocate_list(InstanceKlass::cast(_scratch_classes[i]));
228 }
229 }
230 // Free os::malloc allocated memory in load_new_class_version.
231 os::free(_scratch_classes);
232 _timer_vm_op_prologue.stop();
233 unlock_classes();
234 return false;
235 }
236
237 _timer_vm_op_prologue.stop();
238 return true;
239 }
240
241 void VM_RedefineClasses::doit() {
242 Thread* current = Thread::current();
243
244 if (log_is_enabled(Info, redefine, class, timer)) {
245 _timer_vm_op_doit.start();
246 }
247
248 #if INCLUDE_CDS
249 if (CDSConfig::is_using_archive()) {
250 // Sharing is enabled so we remap the shared readonly space to
251 // shared readwrite, private just in case we need to redefine
252 // a shared class. We do the remap during the doit() phase of
253 // the safepoint to be safer.
254 if (!MetaspaceShared::remap_shared_readonly_as_readwrite()) {
255 log_info(redefine, class, load)("failed to remap shared readonly space to readwrite, private");
256 _res = JVMTI_ERROR_INTERNAL;
257 _timer_vm_op_doit.stop();
258 return;
259 }
260 }
261 #endif
262
263 // Mark methods seen on stack and everywhere else so old methods are not
264 // cleaned up if they're on the stack.
265 MetadataOnStackMark md_on_stack(/*walk_all_metadata*/true, /*redefinition_walk*/true);
266 HandleMark hm(current); // make sure any handles created are deleted
267 // before the stack walk again.
268
269 for (int i = 0; i < _class_count; i++) {
270 redefine_single_class(current, _class_defs[i].klass, _scratch_classes[i]);
271 }
272
273 // Flush all compiled code that depends on the classes redefined.
274 flush_dependent_code();
275
276 // Adjust constantpool caches and vtables for all classes
277 // that reference methods of the evolved classes.
278 // Have to do this after all classes are redefined and all methods that
279 // are redefined are marked as old.
280 AdjustAndCleanMetadata adjust_and_clean_metadata(current);
281 ClassLoaderDataGraph::classes_do(&adjust_and_clean_metadata);
282
283 // JSR-292 support
284 if (_any_class_has_resolved_methods) {
285 bool trace_name_printed = false;
286 ResolvedMethodTable::adjust_method_entries(&trace_name_printed);
287 }
288
289 // Increment flag indicating that some invariants are no longer true.
290 // See jvmtiExport.hpp for detailed explanation.
291 JvmtiExport::increment_redefinition_count();
292
293 // check_class() is optionally called for product bits, but is
294 // always called for non-product bits.
295 #ifdef PRODUCT
296 if (log_is_enabled(Trace, redefine, class, obsolete, metadata)) {
297 #endif
298 log_trace(redefine, class, obsolete, metadata)("calling check_class");
299 CheckClass check_class(current);
300 ClassLoaderDataGraph::classes_do(&check_class);
301 #ifdef PRODUCT
302 }
303 #endif
304
305 // Clean up any metadata now unreferenced while MetadataOnStackMark is set.
306 ClassLoaderDataGraph::clean_deallocate_lists(false);
307
308 _timer_vm_op_doit.stop();
309 }
310
311 void VM_RedefineClasses::doit_epilogue() {
312 unlock_classes();
313
314 // Free os::malloc allocated memory.
315 os::free(_scratch_classes);
316
317 // Reset the_class to null for error printing.
318 _the_class = nullptr;
319
320 if (log_is_enabled(Info, redefine, class, timer)) {
321 // Used to have separate timers for "doit" and "all", but the timer
322 // overhead skewed the measurements.
323 julong doit_time = _timer_vm_op_doit.milliseconds();
324 julong all_time = _timer_vm_op_prologue.milliseconds() + doit_time;
325
326 log_info(redefine, class, timer)
327 ("vm_op: all=" JULONG_FORMAT " prologue=" JULONG_FORMAT " doit=" JULONG_FORMAT,
328 all_time, (julong)_timer_vm_op_prologue.milliseconds(), doit_time);
329 log_info(redefine, class, timer)
330 ("redefine_single_class: phase1=" JULONG_FORMAT " phase2=" JULONG_FORMAT,
331 (julong)_timer_rsc_phase1.milliseconds(), (julong)_timer_rsc_phase2.milliseconds());
332 }
333 }
334
335 bool VM_RedefineClasses::is_modifiable_class(oop klass_mirror) {
336 // classes for primitives cannot be redefined
337 if (java_lang_Class::is_primitive(klass_mirror)) {
338 return false;
339 }
340 Klass* k = java_lang_Class::as_Klass(klass_mirror);
341 // classes for arrays cannot be redefined
342 if (k == nullptr || !k->is_instance_klass()) {
343 return false;
344 }
345
346 // Cannot redefine or retransform a hidden class.
347 if (InstanceKlass::cast(k)->is_hidden()) {
348 return false;
349 }
350 if (InstanceKlass::cast(k) == vmClasses::Continuation_klass()) {
351 // Don't redefine Continuation class. See 8302779.
352 return false;
353 }
354 return true;
355 }
356
357 // Append the current entry at scratch_i in scratch_cp to *merge_cp_p
358 // where the end of *merge_cp_p is specified by *merge_cp_length_p. For
359 // direct CP entries, there is just the current entry to append. For
360 // indirect and double-indirect CP entries, there are zero or more
361 // referenced CP entries along with the current entry to append.
362 // Indirect and double-indirect CP entries are handled by recursive
363 // calls to append_entry() as needed. The referenced CP entries are
364 // always appended to *merge_cp_p before the referee CP entry. These
365 // referenced CP entries may already exist in *merge_cp_p in which case
366 // there is nothing extra to append and only the current entry is
367 // appended.
368 void VM_RedefineClasses::append_entry(const constantPoolHandle& scratch_cp,
369 int scratch_i, constantPoolHandle *merge_cp_p, int *merge_cp_length_p) {
370
371 // append is different depending on entry tag type
372 switch (scratch_cp->tag_at(scratch_i).value()) {
373
374 // The old verifier is implemented outside the VM. It loads classes,
375 // but does not resolve constant pool entries directly so we never
376 // see Class entries here with the old verifier. Similarly the old
377 // verifier does not like Class entries in the input constant pool.
378 // The split-verifier is implemented in the VM so it can optionally
379 // and directly resolve constant pool entries to load classes. The
380 // split-verifier can accept either Class entries or UnresolvedClass
381 // entries in the input constant pool. We revert the appended copy
382 // back to UnresolvedClass so that either verifier will be happy
383 // with the constant pool entry.
384 //
385 // this is an indirect CP entry so it needs special handling
386 case JVM_CONSTANT_Class:
387 case JVM_CONSTANT_UnresolvedClass:
388 {
389 int name_i = scratch_cp->klass_name_index_at(scratch_i);
390 int new_name_i = find_or_append_indirect_entry(scratch_cp, name_i, merge_cp_p,
391 merge_cp_length_p);
392
393 if (new_name_i != name_i) {
394 log_trace(redefine, class, constantpool)
395 ("Class entry@%d name_index change: %d to %d",
396 *merge_cp_length_p, name_i, new_name_i);
397 }
398
399 (*merge_cp_p)->temp_unresolved_klass_at_put(*merge_cp_length_p, new_name_i);
400 if (scratch_i != *merge_cp_length_p) {
401 // The new entry in *merge_cp_p is at a different index than
402 // the new entry in scratch_cp so we need to map the index values.
403 map_index(scratch_cp, scratch_i, *merge_cp_length_p);
404 }
405 (*merge_cp_length_p)++;
406 } break;
407
408 // these are direct CP entries so they can be directly appended,
409 // but double and long take two constant pool entries
410 case JVM_CONSTANT_Double: // fall through
411 case JVM_CONSTANT_Long:
412 {
413 ConstantPool::copy_entry_to(scratch_cp, scratch_i, *merge_cp_p, *merge_cp_length_p);
414
415 if (scratch_i != *merge_cp_length_p) {
416 // The new entry in *merge_cp_p is at a different index than
417 // the new entry in scratch_cp so we need to map the index values.
418 map_index(scratch_cp, scratch_i, *merge_cp_length_p);
419 }
420 (*merge_cp_length_p) += 2;
421 } break;
422
423 // these are direct CP entries so they can be directly appended
424 case JVM_CONSTANT_Float: // fall through
425 case JVM_CONSTANT_Integer: // fall through
426 case JVM_CONSTANT_Utf8: // fall through
427
428 // This was an indirect CP entry, but it has been changed into
429 // Symbol*s so this entry can be directly appended.
430 case JVM_CONSTANT_String: // fall through
431 {
432 ConstantPool::copy_entry_to(scratch_cp, scratch_i, *merge_cp_p, *merge_cp_length_p);
433
434 if (scratch_i != *merge_cp_length_p) {
435 // The new entry in *merge_cp_p is at a different index than
436 // the new entry in scratch_cp so we need to map the index values.
437 map_index(scratch_cp, scratch_i, *merge_cp_length_p);
438 }
439 (*merge_cp_length_p)++;
440 } break;
441
442 // this is an indirect CP entry so it needs special handling
443 case JVM_CONSTANT_NameAndType:
444 {
445 int name_ref_i = scratch_cp->name_ref_index_at(scratch_i);
446 int new_name_ref_i = find_or_append_indirect_entry(scratch_cp, name_ref_i, merge_cp_p,
447 merge_cp_length_p);
448
449 int signature_ref_i = scratch_cp->signature_ref_index_at(scratch_i);
450 int new_signature_ref_i = find_or_append_indirect_entry(scratch_cp, signature_ref_i,
451 merge_cp_p, merge_cp_length_p);
452
453 // If the referenced entries already exist in *merge_cp_p, then
454 // both new_name_ref_i and new_signature_ref_i will both be 0.
455 // In that case, all we are appending is the current entry.
456 if (new_name_ref_i != name_ref_i) {
457 log_trace(redefine, class, constantpool)
458 ("NameAndType entry@%d name_ref_index change: %d to %d",
459 *merge_cp_length_p, name_ref_i, new_name_ref_i);
460 }
461 if (new_signature_ref_i != signature_ref_i) {
462 log_trace(redefine, class, constantpool)
463 ("NameAndType entry@%d signature_ref_index change: %d to %d",
464 *merge_cp_length_p, signature_ref_i, new_signature_ref_i);
465 }
466
467 (*merge_cp_p)->name_and_type_at_put(*merge_cp_length_p,
468 new_name_ref_i, new_signature_ref_i);
469 if (scratch_i != *merge_cp_length_p) {
470 // The new entry in *merge_cp_p is at a different index than
471 // the new entry in scratch_cp so we need to map the index values.
472 map_index(scratch_cp, scratch_i, *merge_cp_length_p);
473 }
474 (*merge_cp_length_p)++;
475 } break;
476
477 // this is a double-indirect CP entry so it needs special handling
478 case JVM_CONSTANT_Fieldref: // fall through
479 case JVM_CONSTANT_InterfaceMethodref: // fall through
480 case JVM_CONSTANT_Methodref:
481 {
482 int klass_ref_i = scratch_cp->uncached_klass_ref_index_at(scratch_i);
483 int new_klass_ref_i = find_or_append_indirect_entry(scratch_cp, klass_ref_i,
484 merge_cp_p, merge_cp_length_p);
485
486 int name_and_type_ref_i = scratch_cp->uncached_name_and_type_ref_index_at(scratch_i);
487 int new_name_and_type_ref_i = find_or_append_indirect_entry(scratch_cp, name_and_type_ref_i,
488 merge_cp_p, merge_cp_length_p);
489
490 const char *entry_name = nullptr;
491 switch (scratch_cp->tag_at(scratch_i).value()) {
492 case JVM_CONSTANT_Fieldref:
493 entry_name = "Fieldref";
494 (*merge_cp_p)->field_at_put(*merge_cp_length_p, new_klass_ref_i,
495 new_name_and_type_ref_i);
496 break;
497 case JVM_CONSTANT_InterfaceMethodref:
498 entry_name = "IFMethodref";
499 (*merge_cp_p)->interface_method_at_put(*merge_cp_length_p,
500 new_klass_ref_i, new_name_and_type_ref_i);
501 break;
502 case JVM_CONSTANT_Methodref:
503 entry_name = "Methodref";
504 (*merge_cp_p)->method_at_put(*merge_cp_length_p, new_klass_ref_i,
505 new_name_and_type_ref_i);
506 break;
507 default:
508 guarantee(false, "bad switch");
509 break;
510 }
511
512 if (klass_ref_i != new_klass_ref_i) {
513 log_trace(redefine, class, constantpool)
514 ("%s entry@%d class_index changed: %d to %d", entry_name, *merge_cp_length_p, klass_ref_i, new_klass_ref_i);
515 }
516 if (name_and_type_ref_i != new_name_and_type_ref_i) {
517 log_trace(redefine, class, constantpool)
518 ("%s entry@%d name_and_type_index changed: %d to %d",
519 entry_name, *merge_cp_length_p, name_and_type_ref_i, new_name_and_type_ref_i);
520 }
521
522 if (scratch_i != *merge_cp_length_p) {
523 // The new entry in *merge_cp_p is at a different index than
524 // the new entry in scratch_cp so we need to map the index values.
525 map_index(scratch_cp, scratch_i, *merge_cp_length_p);
526 }
527 (*merge_cp_length_p)++;
528 } break;
529
530 // this is an indirect CP entry so it needs special handling
531 case JVM_CONSTANT_MethodType:
532 {
533 int ref_i = scratch_cp->method_type_index_at(scratch_i);
534 int new_ref_i = find_or_append_indirect_entry(scratch_cp, ref_i, merge_cp_p,
535 merge_cp_length_p);
536 if (new_ref_i != ref_i) {
537 log_trace(redefine, class, constantpool)
538 ("MethodType entry@%d ref_index change: %d to %d", *merge_cp_length_p, ref_i, new_ref_i);
539 }
540 (*merge_cp_p)->method_type_index_at_put(*merge_cp_length_p, new_ref_i);
541 if (scratch_i != *merge_cp_length_p) {
542 // The new entry in *merge_cp_p is at a different index than
543 // the new entry in scratch_cp so we need to map the index values.
544 map_index(scratch_cp, scratch_i, *merge_cp_length_p);
545 }
546 (*merge_cp_length_p)++;
547 } break;
548
549 // this is an indirect CP entry so it needs special handling
550 case JVM_CONSTANT_MethodHandle:
551 {
552 int ref_kind = scratch_cp->method_handle_ref_kind_at(scratch_i);
553 int ref_i = scratch_cp->method_handle_index_at(scratch_i);
554 int new_ref_i = find_or_append_indirect_entry(scratch_cp, ref_i, merge_cp_p,
555 merge_cp_length_p);
556 if (new_ref_i != ref_i) {
557 log_trace(redefine, class, constantpool)
558 ("MethodHandle entry@%d ref_index change: %d to %d", *merge_cp_length_p, ref_i, new_ref_i);
559 }
560 (*merge_cp_p)->method_handle_index_at_put(*merge_cp_length_p, ref_kind, new_ref_i);
561 if (scratch_i != *merge_cp_length_p) {
562 // The new entry in *merge_cp_p is at a different index than
563 // the new entry in scratch_cp so we need to map the index values.
564 map_index(scratch_cp, scratch_i, *merge_cp_length_p);
565 }
566 (*merge_cp_length_p)++;
567 } break;
568
569 // this is an indirect CP entry so it needs special handling
570 case JVM_CONSTANT_Dynamic: // fall through
571 case JVM_CONSTANT_InvokeDynamic:
572 {
573 // Index of the bootstrap specifier in the operands array
574 int old_bs_i = scratch_cp->bootstrap_methods_attribute_index(scratch_i);
575 int new_bs_i = find_or_append_operand(scratch_cp, old_bs_i, merge_cp_p,
576 merge_cp_length_p);
577 // The bootstrap method NameAndType_info index
578 int old_ref_i = scratch_cp->bootstrap_name_and_type_ref_index_at(scratch_i);
579 int new_ref_i = find_or_append_indirect_entry(scratch_cp, old_ref_i, merge_cp_p,
580 merge_cp_length_p);
581 if (new_bs_i != old_bs_i) {
582 log_trace(redefine, class, constantpool)
583 ("Dynamic entry@%d bootstrap_method_attr_index change: %d to %d",
584 *merge_cp_length_p, old_bs_i, new_bs_i);
585 }
586 if (new_ref_i != old_ref_i) {
587 log_trace(redefine, class, constantpool)
588 ("Dynamic entry@%d name_and_type_index change: %d to %d", *merge_cp_length_p, old_ref_i, new_ref_i);
589 }
590
591 if (scratch_cp->tag_at(scratch_i).is_dynamic_constant())
592 (*merge_cp_p)->dynamic_constant_at_put(*merge_cp_length_p, new_bs_i, new_ref_i);
593 else
594 (*merge_cp_p)->invoke_dynamic_at_put(*merge_cp_length_p, new_bs_i, new_ref_i);
595 if (scratch_i != *merge_cp_length_p) {
596 // The new entry in *merge_cp_p is at a different index than
597 // the new entry in scratch_cp so we need to map the index values.
598 map_index(scratch_cp, scratch_i, *merge_cp_length_p);
599 }
600 (*merge_cp_length_p)++;
601 } break;
602
603 // At this stage, Class or UnresolvedClass could be in scratch_cp, but not
604 // ClassIndex
605 case JVM_CONSTANT_ClassIndex: // fall through
606
607 // Invalid is used as the tag for the second constant pool entry
608 // occupied by JVM_CONSTANT_Double or JVM_CONSTANT_Long. It should
609 // not be seen by itself.
610 case JVM_CONSTANT_Invalid: // fall through
611
612 // At this stage, String could be here, but not StringIndex
613 case JVM_CONSTANT_StringIndex: // fall through
614
615 // At this stage JVM_CONSTANT_UnresolvedClassInError should not be here
616 case JVM_CONSTANT_UnresolvedClassInError: // fall through
617
618 default:
619 {
620 // leave a breadcrumb
621 jbyte bad_value = scratch_cp->tag_at(scratch_i).value();
622 ShouldNotReachHere();
623 } break;
624 } // end switch tag value
625 } // end append_entry()
626
627
628 u2 VM_RedefineClasses::find_or_append_indirect_entry(const constantPoolHandle& scratch_cp,
629 int ref_i, constantPoolHandle *merge_cp_p, int *merge_cp_length_p) {
630
631 int new_ref_i = ref_i;
632 bool match = (ref_i < *merge_cp_length_p) &&
633 scratch_cp->compare_entry_to(ref_i, *merge_cp_p, ref_i);
634
635 if (!match) {
636 // forward reference in *merge_cp_p or not a direct match
637 int found_i = scratch_cp->find_matching_entry(ref_i, *merge_cp_p);
638 if (found_i != 0) {
639 guarantee(found_i != ref_i, "compare_entry_to() and find_matching_entry() do not agree");
640 // Found a matching entry somewhere else in *merge_cp_p so just need a mapping entry.
641 new_ref_i = found_i;
642 map_index(scratch_cp, ref_i, found_i);
643 } else {
644 // no match found so we have to append this entry to *merge_cp_p
645 append_entry(scratch_cp, ref_i, merge_cp_p, merge_cp_length_p);
646 // The above call to append_entry() can only append one entry
647 // so the post call query of *merge_cp_length_p is only for
648 // the sake of consistency.
649 new_ref_i = *merge_cp_length_p - 1;
650 }
651 }
652
653 // constant pool indices are u2, unless the merged constant pool overflows which
654 // we don't check for.
655 return checked_cast<u2>(new_ref_i);
656 } // end find_or_append_indirect_entry()
657
658
659 // Append a bootstrap specifier into the merge_cp operands that is semantically equal
660 // to the scratch_cp operands bootstrap specifier passed by the old_bs_i index.
661 // Recursively append new merge_cp entries referenced by the new bootstrap specifier.
662 void VM_RedefineClasses::append_operand(const constantPoolHandle& scratch_cp, int old_bs_i,
663 constantPoolHandle *merge_cp_p, int *merge_cp_length_p) {
664
665 u2 old_ref_i = scratch_cp->operand_bootstrap_method_ref_index_at(old_bs_i);
666 u2 new_ref_i = find_or_append_indirect_entry(scratch_cp, old_ref_i, merge_cp_p,
667 merge_cp_length_p);
668 if (new_ref_i != old_ref_i) {
669 log_trace(redefine, class, constantpool)
670 ("operands entry@%d bootstrap method ref_index change: %d to %d", _operands_cur_length, old_ref_i, new_ref_i);
671 }
672
673 Array<u2>* merge_ops = (*merge_cp_p)->operands();
674 int new_bs_i = _operands_cur_length;
675 // We have _operands_cur_length == 0 when the merge_cp operands is empty yet.
676 // However, the operand_offset_at(0) was set in the extend_operands() call.
677 int new_base = (new_bs_i == 0) ? (*merge_cp_p)->operand_offset_at(0)
678 : (*merge_cp_p)->operand_next_offset_at(new_bs_i - 1);
679 u2 argc = scratch_cp->operand_argument_count_at(old_bs_i);
680
681 ConstantPool::operand_offset_at_put(merge_ops, _operands_cur_length, new_base);
682 merge_ops->at_put(new_base++, new_ref_i);
683 merge_ops->at_put(new_base++, argc);
684
685 for (int i = 0; i < argc; i++) {
686 u2 old_arg_ref_i = scratch_cp->operand_argument_index_at(old_bs_i, i);
687 u2 new_arg_ref_i = find_or_append_indirect_entry(scratch_cp, old_arg_ref_i, merge_cp_p,
688 merge_cp_length_p);
689 merge_ops->at_put(new_base++, new_arg_ref_i);
690 if (new_arg_ref_i != old_arg_ref_i) {
691 log_trace(redefine, class, constantpool)
692 ("operands entry@%d bootstrap method argument ref_index change: %d to %d",
693 _operands_cur_length, old_arg_ref_i, new_arg_ref_i);
694 }
695 }
696 if (old_bs_i != _operands_cur_length) {
697 // The bootstrap specifier in *merge_cp_p is at a different index than
698 // that in scratch_cp so we need to map the index values.
699 map_operand_index(old_bs_i, new_bs_i);
700 }
701 _operands_cur_length++;
702 } // end append_operand()
703
704
705 int VM_RedefineClasses::find_or_append_operand(const constantPoolHandle& scratch_cp,
706 int old_bs_i, constantPoolHandle *merge_cp_p, int *merge_cp_length_p) {
707
708 int new_bs_i = old_bs_i; // bootstrap specifier index
709 bool match = (old_bs_i < _operands_cur_length) &&
710 scratch_cp->compare_operand_to(old_bs_i, *merge_cp_p, old_bs_i);
711
712 if (!match) {
713 // forward reference in *merge_cp_p or not a direct match
714 int found_i = scratch_cp->find_matching_operand(old_bs_i, *merge_cp_p,
715 _operands_cur_length);
716 if (found_i != -1) {
717 guarantee(found_i != old_bs_i, "compare_operand_to() and find_matching_operand() disagree");
718 // found a matching operand somewhere else in *merge_cp_p so just need a mapping
719 new_bs_i = found_i;
720 map_operand_index(old_bs_i, found_i);
721 } else {
722 // no match found so we have to append this bootstrap specifier to *merge_cp_p
723 append_operand(scratch_cp, old_bs_i, merge_cp_p, merge_cp_length_p);
724 new_bs_i = _operands_cur_length - 1;
725 }
726 }
727 return new_bs_i;
728 } // end find_or_append_operand()
729
730
731 void VM_RedefineClasses::finalize_operands_merge(const constantPoolHandle& merge_cp, TRAPS) {
732 if (merge_cp->operands() == nullptr) {
733 return;
734 }
735 // Shrink the merge_cp operands
736 merge_cp->shrink_operands(_operands_cur_length, CHECK);
737
738 if (log_is_enabled(Trace, redefine, class, constantpool)) {
739 // don't want to loop unless we are tracing
740 int count = 0;
741 for (int i = 1; i < _operands_index_map_p->length(); i++) {
742 int value = _operands_index_map_p->at(i);
743 if (value != -1) {
744 log_trace(redefine, class, constantpool)("operands_index_map[%d]: old=%d new=%d", count, i, value);
745 count++;
746 }
747 }
748 }
749 // Clean-up
750 _operands_index_map_p = nullptr;
751 _operands_cur_length = 0;
752 _operands_index_map_count = 0;
753 } // end finalize_operands_merge()
754
755 // Symbol* comparator for qsort
756 // The caller must have an active ResourceMark.
757 static int symcmp(const void* a, const void* b) {
758 char* astr = (*(Symbol**)a)->as_C_string();
759 char* bstr = (*(Symbol**)b)->as_C_string();
760 return strcmp(astr, bstr);
761 }
762
763 // The caller must have an active ResourceMark.
764 static jvmtiError check_attribute_arrays(const char* attr_name,
765 InstanceKlass* the_class, InstanceKlass* scratch_class,
766 Array<u2>* the_array, Array<u2>* scr_array) {
767 bool the_array_exists = the_array != Universe::the_empty_short_array();
768 bool scr_array_exists = scr_array != Universe::the_empty_short_array();
769
770 int array_len = the_array->length();
771 if (the_array_exists && scr_array_exists) {
772 if (array_len != scr_array->length()) {
773 log_trace(redefine, class)
774 ("redefined class %s attribute change error: %s len=%d changed to len=%d",
775 the_class->external_name(), attr_name, array_len, scr_array->length());
776 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_CLASS_ATTRIBUTE_CHANGED;
777 }
778
779 // The order of entries in the attribute array is not specified so we
780 // have to explicitly check for the same contents. We do this by copying
781 // the referenced symbols into their own arrays, sorting them and then
782 // comparing each element pair.
783
784 Symbol** the_syms = NEW_RESOURCE_ARRAY_RETURN_NULL(Symbol*, array_len);
785 Symbol** scr_syms = NEW_RESOURCE_ARRAY_RETURN_NULL(Symbol*, array_len);
786
787 if (the_syms == nullptr || scr_syms == nullptr) {
788 return JVMTI_ERROR_OUT_OF_MEMORY;
789 }
790
791 for (int i = 0; i < array_len; i++) {
792 int the_cp_index = the_array->at(i);
793 int scr_cp_index = scr_array->at(i);
794 the_syms[i] = the_class->constants()->klass_name_at(the_cp_index);
795 scr_syms[i] = scratch_class->constants()->klass_name_at(scr_cp_index);
796 }
797
798 qsort(the_syms, array_len, sizeof(Symbol*), symcmp);
799 qsort(scr_syms, array_len, sizeof(Symbol*), symcmp);
800
801 for (int i = 0; i < array_len; i++) {
802 if (the_syms[i] != scr_syms[i]) {
803 log_info(redefine, class)
804 ("redefined class %s attribute change error: %s[%d]: %s changed to %s",
805 the_class->external_name(), attr_name, i,
806 the_syms[i]->as_C_string(), scr_syms[i]->as_C_string());
807 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_CLASS_ATTRIBUTE_CHANGED;
808 }
809 }
810 } else if (the_array_exists ^ scr_array_exists) {
811 const char* action_str = (the_array_exists) ? "removed" : "added";
812 log_info(redefine, class)
813 ("redefined class %s attribute change error: %s attribute %s",
814 the_class->external_name(), attr_name, action_str);
815 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_CLASS_ATTRIBUTE_CHANGED;
816 }
817 return JVMTI_ERROR_NONE;
818 }
819
820 static jvmtiError check_nest_attributes(InstanceKlass* the_class,
821 InstanceKlass* scratch_class) {
822 // Check whether the class NestHost attribute has been changed.
823 Thread* thread = Thread::current();
824 ResourceMark rm(thread);
825 u2 the_nest_host_idx = the_class->nest_host_index();
826 u2 scr_nest_host_idx = scratch_class->nest_host_index();
827
828 if (the_nest_host_idx != 0 && scr_nest_host_idx != 0) {
829 Symbol* the_sym = the_class->constants()->klass_name_at(the_nest_host_idx);
830 Symbol* scr_sym = scratch_class->constants()->klass_name_at(scr_nest_host_idx);
831 if (the_sym != scr_sym) {
832 log_info(redefine, class, nestmates)
833 ("redefined class %s attribute change error: NestHost class: %s replaced with: %s",
834 the_class->external_name(), the_sym->as_C_string(), scr_sym->as_C_string());
835 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_CLASS_ATTRIBUTE_CHANGED;
836 }
837 } else if ((the_nest_host_idx == 0) ^ (scr_nest_host_idx == 0)) {
838 const char* action_str = (the_nest_host_idx != 0) ? "removed" : "added";
839 log_info(redefine, class, nestmates)
840 ("redefined class %s attribute change error: NestHost attribute %s",
841 the_class->external_name(), action_str);
842 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_CLASS_ATTRIBUTE_CHANGED;
843 }
844
845 // Check whether the class NestMembers attribute has been changed.
846 return check_attribute_arrays("NestMembers",
847 the_class, scratch_class,
848 the_class->nest_members(),
849 scratch_class->nest_members());
850 }
851
852 // Return an error status if the class Record attribute was changed.
853 static jvmtiError check_record_attribute(InstanceKlass* the_class, InstanceKlass* scratch_class) {
854 // Get lists of record components.
855 Array<RecordComponent*>* the_record = the_class->record_components();
856 Array<RecordComponent*>* scr_record = scratch_class->record_components();
857 bool the_record_exists = the_record != nullptr;
858 bool scr_record_exists = scr_record != nullptr;
859
860 if (the_record_exists && scr_record_exists) {
861 int the_num_components = the_record->length();
862 int scr_num_components = scr_record->length();
863 if (the_num_components != scr_num_components) {
864 log_info(redefine, class, record)
865 ("redefined class %s attribute change error: Record num_components=%d changed to num_components=%d",
866 the_class->external_name(), the_num_components, scr_num_components);
867 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_CLASS_ATTRIBUTE_CHANGED;
868 }
869
870 // Compare each field in each record component.
871 ConstantPool* the_cp = the_class->constants();
872 ConstantPool* scr_cp = scratch_class->constants();
873 for (int x = 0; x < the_num_components; x++) {
874 RecordComponent* the_component = the_record->at(x);
875 RecordComponent* scr_component = scr_record->at(x);
876 const Symbol* const the_name = the_cp->symbol_at(the_component->name_index());
877 const Symbol* const scr_name = scr_cp->symbol_at(scr_component->name_index());
878 const Symbol* const the_descr = the_cp->symbol_at(the_component->descriptor_index());
879 const Symbol* const scr_descr = scr_cp->symbol_at(scr_component->descriptor_index());
880 if (the_name != scr_name || the_descr != scr_descr) {
881 log_info(redefine, class, record)
882 ("redefined class %s attribute change error: Record name_index, descriptor_index, and/or attributes_count changed",
883 the_class->external_name());
884 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_CLASS_ATTRIBUTE_CHANGED;
885 }
886
887 int the_gen_sig = the_component->generic_signature_index();
888 int scr_gen_sig = scr_component->generic_signature_index();
889 const Symbol* const the_gen_sig_sym = (the_gen_sig == 0 ? nullptr :
890 the_cp->symbol_at(the_component->generic_signature_index()));
891 const Symbol* const scr_gen_sig_sym = (scr_gen_sig == 0 ? nullptr :
892 scr_cp->symbol_at(scr_component->generic_signature_index()));
893 if (the_gen_sig_sym != scr_gen_sig_sym) {
894 log_info(redefine, class, record)
895 ("redefined class %s attribute change error: Record generic_signature attribute changed",
896 the_class->external_name());
897 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_CLASS_ATTRIBUTE_CHANGED;
898 }
899
900 // It's okay if a record component's annotations were changed.
901 }
902
903 } else if (the_record_exists ^ scr_record_exists) {
904 const char* action_str = (the_record_exists) ? "removed" : "added";
905 log_info(redefine, class, record)
906 ("redefined class %s attribute change error: Record attribute %s",
907 the_class->external_name(), action_str);
908 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_CLASS_ATTRIBUTE_CHANGED;
909 }
910
911 return JVMTI_ERROR_NONE;
912 }
913
914
915 static jvmtiError check_permitted_subclasses_attribute(InstanceKlass* the_class,
916 InstanceKlass* scratch_class) {
917 Thread* thread = Thread::current();
918 ResourceMark rm(thread);
919
920 // Check whether the class PermittedSubclasses attribute has been changed.
921 return check_attribute_arrays("PermittedSubclasses",
922 the_class, scratch_class,
923 the_class->permitted_subclasses(),
924 scratch_class->permitted_subclasses());
925 }
926
927 static bool can_add_or_delete(Method* m) {
928 // Compatibility mode
929 return (AllowRedefinitionToAddDeleteMethods &&
930 (m->is_private() && (m->is_static() || m->is_final())));
931 }
932
933 jvmtiError VM_RedefineClasses::compare_and_normalize_class_versions(
934 InstanceKlass* the_class,
935 InstanceKlass* scratch_class) {
936 int i;
937
938 // Check superclasses, or rather their names, since superclasses themselves can be
939 // requested to replace.
940 // Check for null superclass first since this might be java.lang.Object
941 if (the_class->super() != scratch_class->super() &&
942 (the_class->super() == nullptr || scratch_class->super() == nullptr ||
943 the_class->super()->name() !=
944 scratch_class->super()->name())) {
945 log_info(redefine, class, normalize)
946 ("redefined class %s superclass change error: superclass changed from %s to %s.",
947 the_class->external_name(),
948 the_class->super() == nullptr ? "null" : the_class->super()->external_name(),
949 scratch_class->super() == nullptr ? "null" : scratch_class->super()->external_name());
950 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_HIERARCHY_CHANGED;
951 }
952
953 // Check if the number, names and order of directly implemented interfaces are the same.
954 // I think in principle we should just check if the sets of names of directly implemented
955 // interfaces are the same, i.e. the order of declaration (which, however, if changed in the
956 // .java file, also changes in .class file) should not matter. However, comparing sets is
957 // technically a bit more difficult, and, more importantly, I am not sure at present that the
958 // order of interfaces does not matter on the implementation level, i.e. that the VM does not
959 // rely on it somewhere.
960 Array<InstanceKlass*>* k_interfaces = the_class->local_interfaces();
961 Array<InstanceKlass*>* k_new_interfaces = scratch_class->local_interfaces();
962 int n_intfs = k_interfaces->length();
963 if (n_intfs != k_new_interfaces->length()) {
964 log_info(redefine, class, normalize)
965 ("redefined class %s interfaces change error: number of implemented interfaces changed from %d to %d.",
966 the_class->external_name(), n_intfs, k_new_interfaces->length());
967 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_HIERARCHY_CHANGED;
968 }
969 for (i = 0; i < n_intfs; i++) {
970 if (k_interfaces->at(i)->name() !=
971 k_new_interfaces->at(i)->name()) {
972 log_info(redefine, class, normalize)
973 ("redefined class %s interfaces change error: interface changed from %s to %s.",
974 the_class->external_name(),
975 k_interfaces->at(i)->external_name(), k_new_interfaces->at(i)->external_name());
976 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_HIERARCHY_CHANGED;
977 }
978 }
979
980 // Check whether class is in the error init state.
981 if (the_class->is_in_error_state()) {
982 log_info(redefine, class, normalize)
983 ("redefined class %s is in error init state.", the_class->external_name());
984 // TBD #5057930: special error code is needed in 1.6
985 return JVMTI_ERROR_INVALID_CLASS;
986 }
987
988 // Check whether the nest-related attributes have been changed.
989 jvmtiError err = check_nest_attributes(the_class, scratch_class);
990 if (err != JVMTI_ERROR_NONE) {
991 return err;
992 }
993
994 // Check whether the Record attribute has been changed.
995 err = check_record_attribute(the_class, scratch_class);
996 if (err != JVMTI_ERROR_NONE) {
997 return err;
998 }
999
1000 // Check whether the PermittedSubclasses attribute has been changed.
1001 err = check_permitted_subclasses_attribute(the_class, scratch_class);
1002 if (err != JVMTI_ERROR_NONE) {
1003 return err;
1004 }
1005
1006 // Check whether class modifiers are the same.
1007 jushort old_flags = (jushort) the_class->access_flags().get_flags();
1008 jushort new_flags = (jushort) scratch_class->access_flags().get_flags();
1009 if (old_flags != new_flags) {
1010 log_info(redefine, class, normalize)
1011 ("redefined class %s modifiers change error: modifiers changed from %d to %d.",
1012 the_class->external_name(), old_flags, new_flags);
1013 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_CLASS_MODIFIERS_CHANGED;
1014 }
1015
1016 // Check if the number, names, types and order of fields declared in these classes
1017 // are the same.
1018 JavaFieldStream old_fs(the_class);
1019 JavaFieldStream new_fs(scratch_class);
1020 for (; !old_fs.done() && !new_fs.done(); old_fs.next(), new_fs.next()) {
1021 // name and signature
1022 Symbol* name_sym1 = the_class->constants()->symbol_at(old_fs.name_index());
1023 Symbol* sig_sym1 = the_class->constants()->symbol_at(old_fs.signature_index());
1024 Symbol* name_sym2 = scratch_class->constants()->symbol_at(new_fs.name_index());
1025 Symbol* sig_sym2 = scratch_class->constants()->symbol_at(new_fs.signature_index());
1026 if (name_sym1 != name_sym2 || sig_sym1 != sig_sym2) {
1027 log_info(redefine, class, normalize)
1028 ("redefined class %s fields change error: field %s %s changed to %s %s.",
1029 the_class->external_name(),
1030 sig_sym1->as_C_string(), name_sym1->as_C_string(),
1031 sig_sym2->as_C_string(), name_sym2->as_C_string());
1032 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_SCHEMA_CHANGED;
1033 }
1034 // offset
1035 if (old_fs.offset() != new_fs.offset()) {
1036 log_info(redefine, class, normalize)
1037 ("redefined class %s field %s change error: offset changed from %d to %d.",
1038 the_class->external_name(), name_sym2->as_C_string(), old_fs.offset(), new_fs.offset());
1039 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_SCHEMA_CHANGED;
1040 }
1041 // access
1042 old_flags = old_fs.access_flags().as_short();
1043 new_flags = new_fs.access_flags().as_short();
1044 if ((old_flags ^ new_flags) & JVM_RECOGNIZED_FIELD_MODIFIERS) {
1045 log_info(redefine, class, normalize)
1046 ("redefined class %s field %s change error: modifiers changed from %d to %d.",
1047 the_class->external_name(), name_sym2->as_C_string(), old_flags, new_flags);
1048 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_SCHEMA_CHANGED;
1049 }
1050 }
1051
1052 // If both streams aren't done then we have a differing number of
1053 // fields.
1054 if (!old_fs.done() || !new_fs.done()) {
1055 const char* action = old_fs.done() ? "added" : "deleted";
1056 log_info(redefine, class, normalize)
1057 ("redefined class %s fields change error: some fields were %s.",
1058 the_class->external_name(), action);
1059 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_SCHEMA_CHANGED;
1060 }
1061
1062 // Do a parallel walk through the old and new methods. Detect
1063 // cases where they match (exist in both), have been added in
1064 // the new methods, or have been deleted (exist only in the
1065 // old methods). The class file parser places methods in order
1066 // by method name, but does not order overloaded methods by
1067 // signature. In order to determine what fate befell the methods,
1068 // this code places the overloaded new methods that have matching
1069 // old methods in the same order as the old methods and places
1070 // new overloaded methods at the end of overloaded methods of
1071 // that name. The code for this order normalization is adapted
1072 // from the algorithm used in InstanceKlass::find_method().
1073 // Since we are swapping out of order entries as we find them,
1074 // we only have to search forward through the overloaded methods.
1075 // Methods which are added and have the same name as an existing
1076 // method (but different signature) will be put at the end of
1077 // the methods with that name, and the name mismatch code will
1078 // handle them.
1079 Array<Method*>* k_old_methods(the_class->methods());
1080 Array<Method*>* k_new_methods(scratch_class->methods());
1081 int n_old_methods = k_old_methods->length();
1082 int n_new_methods = k_new_methods->length();
1083 Thread* thread = Thread::current();
1084
1085 int ni = 0;
1086 int oi = 0;
1087 while (true) {
1088 Method* k_old_method;
1089 Method* k_new_method;
1090 enum { matched, added, deleted, undetermined } method_was = undetermined;
1091
1092 if (oi >= n_old_methods) {
1093 if (ni >= n_new_methods) {
1094 break; // we've looked at everything, done
1095 }
1096 // New method at the end
1097 k_new_method = k_new_methods->at(ni);
1098 method_was = added;
1099 } else if (ni >= n_new_methods) {
1100 // Old method, at the end, is deleted
1101 k_old_method = k_old_methods->at(oi);
1102 method_was = deleted;
1103 } else {
1104 // There are more methods in both the old and new lists
1105 k_old_method = k_old_methods->at(oi);
1106 k_new_method = k_new_methods->at(ni);
1107 if (k_old_method->name() != k_new_method->name()) {
1108 // Methods are sorted by method name, so a mismatch means added
1109 // or deleted
1110 if (k_old_method->name()->fast_compare(k_new_method->name()) > 0) {
1111 method_was = added;
1112 } else {
1113 method_was = deleted;
1114 }
1115 } else if (k_old_method->signature() == k_new_method->signature()) {
1116 // Both the name and signature match
1117 method_was = matched;
1118 } else {
1119 // The name matches, but the signature doesn't, which means we have to
1120 // search forward through the new overloaded methods.
1121 int nj; // outside the loop for post-loop check
1122 for (nj = ni + 1; nj < n_new_methods; nj++) {
1123 Method* m = k_new_methods->at(nj);
1124 if (k_old_method->name() != m->name()) {
1125 // reached another method name so no more overloaded methods
1126 method_was = deleted;
1127 break;
1128 }
1129 if (k_old_method->signature() == m->signature()) {
1130 // found a match so swap the methods
1131 k_new_methods->at_put(ni, m);
1132 k_new_methods->at_put(nj, k_new_method);
1133 k_new_method = m;
1134 method_was = matched;
1135 break;
1136 }
1137 }
1138
1139 if (nj >= n_new_methods) {
1140 // reached the end without a match; so method was deleted
1141 method_was = deleted;
1142 }
1143 }
1144 }
1145
1146 switch (method_was) {
1147 case matched:
1148 // methods match, be sure modifiers do too
1149 old_flags = (jushort) k_old_method->access_flags().get_flags();
1150 new_flags = (jushort) k_new_method->access_flags().get_flags();
1151 if ((old_flags ^ new_flags) & ~(JVM_ACC_NATIVE)) {
1152 log_info(redefine, class, normalize)
1153 ("redefined class %s method %s modifiers error: modifiers changed from %d to %d",
1154 the_class->external_name(), k_old_method->name_and_sig_as_C_string(), old_flags, new_flags);
1155 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_METHOD_MODIFIERS_CHANGED;
1156 }
1157 {
1158 u2 new_num = k_new_method->method_idnum();
1159 u2 old_num = k_old_method->method_idnum();
1160 if (new_num != old_num) {
1161 Method* idnum_owner = scratch_class->method_with_idnum(old_num);
1162 if (idnum_owner != nullptr) {
1163 // There is already a method assigned this idnum -- switch them
1164 // Take current and original idnum from the new_method
1165 idnum_owner->set_method_idnum(new_num);
1166 idnum_owner->set_orig_method_idnum(k_new_method->orig_method_idnum());
1167 }
1168 // Take current and original idnum from the old_method
1169 k_new_method->set_method_idnum(old_num);
1170 k_new_method->set_orig_method_idnum(k_old_method->orig_method_idnum());
1171 if (thread->has_pending_exception()) {
1172 return JVMTI_ERROR_OUT_OF_MEMORY;
1173 }
1174 }
1175 }
1176 JFR_ONLY(k_new_method->copy_trace_flags(k_old_method->trace_flags());)
1177 log_trace(redefine, class, normalize)
1178 ("Method matched: new: %s [%d] == old: %s [%d]",
1179 k_new_method->name_and_sig_as_C_string(), ni, k_old_method->name_and_sig_as_C_string(), oi);
1180 // advance to next pair of methods
1181 ++oi;
1182 ++ni;
1183 break;
1184 case added:
1185 // method added, see if it is OK
1186 if (!can_add_or_delete(k_new_method)) {
1187 log_info(redefine, class, normalize)
1188 ("redefined class %s methods error: added method: %s [%d]",
1189 the_class->external_name(), k_new_method->name_and_sig_as_C_string(), ni);
1190 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_METHOD_ADDED;
1191 }
1192 {
1193 u2 num = the_class->next_method_idnum();
1194 if (num == ConstMethod::UNSET_IDNUM) {
1195 // cannot add any more methods
1196 log_info(redefine, class, normalize)
1197 ("redefined class %s methods error: can't create ID for new method %s [%d]",
1198 the_class->external_name(), k_new_method->name_and_sig_as_C_string(), ni);
1199 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_METHOD_ADDED;
1200 }
1201 u2 new_num = k_new_method->method_idnum();
1202 Method* idnum_owner = scratch_class->method_with_idnum(num);
1203 if (idnum_owner != nullptr) {
1204 // There is already a method assigned this idnum -- switch them
1205 // Take current and original idnum from the new_method
1206 idnum_owner->set_method_idnum(new_num);
1207 idnum_owner->set_orig_method_idnum(k_new_method->orig_method_idnum());
1208 }
1209 k_new_method->set_method_idnum(num);
1210 k_new_method->set_orig_method_idnum(num);
1211 if (thread->has_pending_exception()) {
1212 return JVMTI_ERROR_OUT_OF_MEMORY;
1213 }
1214 }
1215 log_trace(redefine, class, normalize)
1216 ("Method added: new: %s [%d]", k_new_method->name_and_sig_as_C_string(), ni);
1217 ++ni; // advance to next new method
1218 break;
1219 case deleted:
1220 // method deleted, see if it is OK
1221 if (!can_add_or_delete(k_old_method)) {
1222 log_info(redefine, class, normalize)
1223 ("redefined class %s methods error: deleted method %s [%d]",
1224 the_class->external_name(), k_old_method->name_and_sig_as_C_string(), oi);
1225 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_METHOD_DELETED;
1226 }
1227 log_trace(redefine, class, normalize)
1228 ("Method deleted: old: %s [%d]", k_old_method->name_and_sig_as_C_string(), oi);
1229 ++oi; // advance to next old method
1230 break;
1231 default:
1232 ShouldNotReachHere();
1233 }
1234 }
1235
1236 return JVMTI_ERROR_NONE;
1237 }
1238
1239
1240 // Find new constant pool index value for old constant pool index value
1241 // by searching the index map. Returns zero (0) if there is no mapped
1242 // value for the old constant pool index.
1243 u2 VM_RedefineClasses::find_new_index(int old_index) {
1244 if (_index_map_count == 0) {
1245 // map is empty so nothing can be found
1246 return 0;
1247 }
1248
1249 if (old_index < 1 || old_index >= _index_map_p->length()) {
1250 // The old_index is out of range so it is not mapped. This should
1251 // not happen in regular constant pool merging use, but it can
1252 // happen if a corrupt annotation is processed.
1253 return 0;
1254 }
1255
1256 int value = _index_map_p->at(old_index);
1257 if (value == -1) {
1258 // the old_index is not mapped
1259 return 0;
1260 }
1261
1262 // constant pool indices are u2, unless the merged constant pool overflows which
1263 // we don't check for.
1264 return checked_cast<u2>(value);
1265 } // end find_new_index()
1266
1267
1268 // Find new bootstrap specifier index value for old bootstrap specifier index
1269 // value by searching the index map. Returns unused index (-1) if there is
1270 // no mapped value for the old bootstrap specifier index.
1271 int VM_RedefineClasses::find_new_operand_index(int old_index) {
1272 if (_operands_index_map_count == 0) {
1273 // map is empty so nothing can be found
1274 return -1;
1275 }
1276
1277 if (old_index == -1 || old_index >= _operands_index_map_p->length()) {
1278 // The old_index is out of range so it is not mapped.
1279 // This should not happen in regular constant pool merging use.
1280 return -1;
1281 }
1282
1283 int value = _operands_index_map_p->at(old_index);
1284 if (value == -1) {
1285 // the old_index is not mapped
1286 return -1;
1287 }
1288
1289 return value;
1290 } // end find_new_operand_index()
1291
1292
1293 // The bug 6214132 caused the verification to fail.
1294 // 1. What's done in RedefineClasses() before verification:
1295 // a) A reference to the class being redefined (_the_class) and a
1296 // reference to new version of the class (_scratch_class) are
1297 // saved here for use during the bytecode verification phase of
1298 // RedefineClasses.
1299 // b) The _java_mirror field from _the_class is copied to the
1300 // _java_mirror field in _scratch_class. This means that a jclass
1301 // returned for _the_class or _scratch_class will refer to the
1302 // same Java mirror. The verifier will see the "one true mirror"
1303 // for the class being verified.
1304 // 2. See comments in JvmtiThreadState for what is done during verification.
1305
1306 class RedefineVerifyMark : public StackObj {
1307 private:
1308 JvmtiThreadState* _state;
1309 Klass* _scratch_class;
1310 OopHandle _scratch_mirror;
1311
1312 public:
1313
1314 RedefineVerifyMark(Klass* the_class, Klass* scratch_class,
1315 JvmtiThreadState* state) : _state(state), _scratch_class(scratch_class)
1316 {
1317 _state->set_class_versions_map(the_class, scratch_class);
1318 _scratch_mirror = the_class->java_mirror_handle(); // this is a copy that is swapped
1319 _scratch_class->swap_java_mirror_handle(_scratch_mirror);
1320 }
1321
1322 ~RedefineVerifyMark() {
1323 // Restore the scratch class's mirror, so when scratch_class is removed
1324 // the correct mirror pointing to it can be cleared.
1325 _scratch_class->swap_java_mirror_handle(_scratch_mirror);
1326 _state->clear_class_versions_map();
1327 }
1328 };
1329
1330
1331 jvmtiError VM_RedefineClasses::load_new_class_versions() {
1332
1333 // For consistency allocate memory using os::malloc wrapper.
1334 _scratch_classes = (InstanceKlass**)
1335 os::malloc(sizeof(InstanceKlass*) * _class_count, mtClass);
1336 if (_scratch_classes == nullptr) {
1337 return JVMTI_ERROR_OUT_OF_MEMORY;
1338 }
1339 // Zero initialize the _scratch_classes array.
1340 for (int i = 0; i < _class_count; i++) {
1341 _scratch_classes[i] = nullptr;
1342 }
1343
1344 JavaThread* current = JavaThread::current();
1345 ResourceMark rm(current);
1346
1347 JvmtiThreadState *state = JvmtiThreadState::state_for(current);
1348 // state can only be null if the current thread is exiting which
1349 // should not happen since we're trying to do a RedefineClasses
1350 guarantee(state != nullptr, "exiting thread calling load_new_class_versions");
1351 for (int i = 0; i < _class_count; i++) {
1352 // Create HandleMark so that any handles created while loading new class
1353 // versions are deleted. Constant pools are deallocated while merging
1354 // constant pools
1355 HandleMark hm(current);
1356 InstanceKlass* the_class = get_ik(_class_defs[i].klass);
1357
1358 log_debug(redefine, class, load)
1359 ("loading name=%s kind=%d (avail_mem=" UINT64_FORMAT "K)",
1360 the_class->external_name(), _class_load_kind, os::available_memory() >> 10);
1361
1362 ClassFileStream st((u1*)_class_defs[i].class_bytes,
1363 _class_defs[i].class_byte_count,
1364 "__VM_RedefineClasses__",
1365 ClassFileStream::verify);
1366
1367 // Set redefined class handle in JvmtiThreadState class.
1368 // This redefined class is sent to agent event handler for class file
1369 // load hook event.
1370 state->set_class_being_redefined(the_class, _class_load_kind);
1371
1372 JavaThread* THREAD = current; // For exception macros.
1373 ExceptionMark em(THREAD);
1374 Handle protection_domain(THREAD, the_class->protection_domain());
1375 ClassLoadInfo cl_info(protection_domain);
1376 // Parse and create a class from the bytes, but this class isn't added
1377 // to the dictionary, so do not call resolve_from_stream.
1378 InstanceKlass* scratch_class = KlassFactory::create_from_stream(&st,
1379 the_class->name(),
1380 the_class->class_loader_data(),
1381 cl_info,
1382 THREAD);
1383
1384 // Clear class_being_redefined just to be sure.
1385 state->clear_class_being_redefined();
1386
1387 // TODO: if this is retransform, and nothing changed we can skip it
1388
1389 // Need to clean up allocated InstanceKlass if there's an error so assign
1390 // the result here. Caller deallocates all the scratch classes in case of
1391 // an error.
1392 _scratch_classes[i] = scratch_class;
1393
1394 if (HAS_PENDING_EXCEPTION) {
1395 Symbol* ex_name = PENDING_EXCEPTION->klass()->name();
1396 log_info(redefine, class, load, exceptions)("create_from_stream exception: '%s'", ex_name->as_C_string());
1397 CLEAR_PENDING_EXCEPTION;
1398
1399 if (ex_name == vmSymbols::java_lang_UnsupportedClassVersionError()) {
1400 return JVMTI_ERROR_UNSUPPORTED_VERSION;
1401 } else if (ex_name == vmSymbols::java_lang_ClassFormatError()) {
1402 return JVMTI_ERROR_INVALID_CLASS_FORMAT;
1403 } else if (ex_name == vmSymbols::java_lang_ClassCircularityError()) {
1404 return JVMTI_ERROR_CIRCULAR_CLASS_DEFINITION;
1405 } else if (ex_name == vmSymbols::java_lang_NoClassDefFoundError()) {
1406 // The message will be "XXX (wrong name: YYY)"
1407 return JVMTI_ERROR_NAMES_DONT_MATCH;
1408 } else if (ex_name == vmSymbols::java_lang_OutOfMemoryError()) {
1409 return JVMTI_ERROR_OUT_OF_MEMORY;
1410 } else { // Just in case more exceptions can be thrown..
1411 return JVMTI_ERROR_FAILS_VERIFICATION;
1412 }
1413 }
1414
1415 // Ensure class is linked before redefine
1416 if (!the_class->is_linked()) {
1417 the_class->link_class(THREAD);
1418 if (HAS_PENDING_EXCEPTION) {
1419 Symbol* ex_name = PENDING_EXCEPTION->klass()->name();
1420 oop message = java_lang_Throwable::message(PENDING_EXCEPTION);
1421 if (message != nullptr) {
1422 char* ex_msg = java_lang_String::as_utf8_string(message);
1423 log_info(redefine, class, load, exceptions)("link_class exception: '%s %s'",
1424 ex_name->as_C_string(), ex_msg);
1425 } else {
1426 log_info(redefine, class, load, exceptions)("link_class exception: '%s'",
1427 ex_name->as_C_string());
1428 }
1429 CLEAR_PENDING_EXCEPTION;
1430 if (ex_name == vmSymbols::java_lang_OutOfMemoryError()) {
1431 return JVMTI_ERROR_OUT_OF_MEMORY;
1432 } else if (ex_name == vmSymbols::java_lang_NoClassDefFoundError()) {
1433 return JVMTI_ERROR_INVALID_CLASS;
1434 } else {
1435 return JVMTI_ERROR_INTERNAL;
1436 }
1437 }
1438 }
1439
1440 // Do the validity checks in compare_and_normalize_class_versions()
1441 // before verifying the byte codes. By doing these checks first, we
1442 // limit the number of functions that require redirection from
1443 // the_class to scratch_class. In particular, we don't have to
1444 // modify JNI GetSuperclass() and thus won't change its performance.
1445 jvmtiError res = compare_and_normalize_class_versions(the_class,
1446 scratch_class);
1447 if (res != JVMTI_ERROR_NONE) {
1448 return res;
1449 }
1450
1451 // verify what the caller passed us
1452 {
1453 // The bug 6214132 caused the verification to fail.
1454 // Information about the_class and scratch_class is temporarily
1455 // recorded into jvmtiThreadState. This data is used to redirect
1456 // the_class to scratch_class in the JVM_* functions called by the
1457 // verifier. Please, refer to jvmtiThreadState.hpp for the detailed
1458 // description.
1459 RedefineVerifyMark rvm(the_class, scratch_class, state);
1460 Verifier::verify(scratch_class, true, THREAD);
1461 }
1462
1463 if (HAS_PENDING_EXCEPTION) {
1464 Symbol* ex_name = PENDING_EXCEPTION->klass()->name();
1465 log_info(redefine, class, load, exceptions)("verify_byte_codes exception: '%s'", ex_name->as_C_string());
1466 CLEAR_PENDING_EXCEPTION;
1467 if (ex_name == vmSymbols::java_lang_OutOfMemoryError()) {
1468 return JVMTI_ERROR_OUT_OF_MEMORY;
1469 } else {
1470 // tell the caller the bytecodes are bad
1471 return JVMTI_ERROR_FAILS_VERIFICATION;
1472 }
1473 }
1474
1475 res = merge_cp_and_rewrite(the_class, scratch_class, THREAD);
1476 if (HAS_PENDING_EXCEPTION) {
1477 Symbol* ex_name = PENDING_EXCEPTION->klass()->name();
1478 log_info(redefine, class, load, exceptions)("merge_cp_and_rewrite exception: '%s'", ex_name->as_C_string());
1479 CLEAR_PENDING_EXCEPTION;
1480 if (ex_name == vmSymbols::java_lang_OutOfMemoryError()) {
1481 return JVMTI_ERROR_OUT_OF_MEMORY;
1482 } else {
1483 return JVMTI_ERROR_INTERNAL;
1484 }
1485 }
1486
1487 #ifdef ASSERT
1488 {
1489 // verify what we have done during constant pool merging
1490 {
1491 RedefineVerifyMark rvm(the_class, scratch_class, state);
1492 Verifier::verify(scratch_class, true, THREAD);
1493 }
1494
1495 if (HAS_PENDING_EXCEPTION) {
1496 Symbol* ex_name = PENDING_EXCEPTION->klass()->name();
1497 log_info(redefine, class, load, exceptions)
1498 ("verify_byte_codes post merge-CP exception: '%s'", ex_name->as_C_string());
1499 CLEAR_PENDING_EXCEPTION;
1500 if (ex_name == vmSymbols::java_lang_OutOfMemoryError()) {
1501 return JVMTI_ERROR_OUT_OF_MEMORY;
1502 } else {
1503 // tell the caller that constant pool merging screwed up
1504 return JVMTI_ERROR_INTERNAL;
1505 }
1506 }
1507 }
1508 #endif // ASSERT
1509
1510 Rewriter::rewrite(scratch_class, THREAD);
1511 if (!HAS_PENDING_EXCEPTION) {
1512 scratch_class->link_methods(THREAD);
1513 }
1514 if (HAS_PENDING_EXCEPTION) {
1515 Symbol* ex_name = PENDING_EXCEPTION->klass()->name();
1516 log_info(redefine, class, load, exceptions)
1517 ("Rewriter::rewrite or link_methods exception: '%s'", ex_name->as_C_string());
1518 CLEAR_PENDING_EXCEPTION;
1519 if (ex_name == vmSymbols::java_lang_OutOfMemoryError()) {
1520 return JVMTI_ERROR_OUT_OF_MEMORY;
1521 } else {
1522 return JVMTI_ERROR_INTERNAL;
1523 }
1524 }
1525
1526 log_debug(redefine, class, load)
1527 ("loaded name=%s (avail_mem=" UINT64_FORMAT "K)", the_class->external_name(), os::available_memory() >> 10);
1528 }
1529
1530 return JVMTI_ERROR_NONE;
1531 }
1532
1533
1534 // Map old_index to new_index as needed. scratch_cp is only needed
1535 // for log calls.
1536 void VM_RedefineClasses::map_index(const constantPoolHandle& scratch_cp,
1537 int old_index, int new_index) {
1538 if (find_new_index(old_index) != 0) {
1539 // old_index is already mapped
1540 return;
1541 }
1542
1543 if (old_index == new_index) {
1544 // no mapping is needed
1545 return;
1546 }
1547
1548 _index_map_p->at_put(old_index, new_index);
1549 _index_map_count++;
1550
1551 log_trace(redefine, class, constantpool)
1552 ("mapped tag %d at index %d to %d", scratch_cp->tag_at(old_index).value(), old_index, new_index);
1553 } // end map_index()
1554
1555
1556 // Map old_index to new_index as needed.
1557 void VM_RedefineClasses::map_operand_index(int old_index, int new_index) {
1558 if (find_new_operand_index(old_index) != -1) {
1559 // old_index is already mapped
1560 return;
1561 }
1562
1563 if (old_index == new_index) {
1564 // no mapping is needed
1565 return;
1566 }
1567
1568 _operands_index_map_p->at_put(old_index, new_index);
1569 _operands_index_map_count++;
1570
1571 log_trace(redefine, class, constantpool)("mapped bootstrap specifier at index %d to %d", old_index, new_index);
1572 } // end map_index()
1573
1574
1575 // Merge old_cp and scratch_cp and return the results of the merge via
1576 // merge_cp_p. The number of entries in *merge_cp_p is returned via
1577 // merge_cp_length_p. The entries in old_cp occupy the same locations
1578 // in *merge_cp_p. Also creates a map of indices from entries in
1579 // scratch_cp to the corresponding entry in *merge_cp_p. Index map
1580 // entries are only created for entries in scratch_cp that occupy a
1581 // different location in *merged_cp_p.
1582 bool VM_RedefineClasses::merge_constant_pools(const constantPoolHandle& old_cp,
1583 const constantPoolHandle& scratch_cp, constantPoolHandle *merge_cp_p,
1584 int *merge_cp_length_p, TRAPS) {
1585
1586 if (merge_cp_p == nullptr) {
1587 assert(false, "caller must provide scratch constantPool");
1588 return false; // robustness
1589 }
1590 if (merge_cp_length_p == nullptr) {
1591 assert(false, "caller must provide scratch CP length");
1592 return false; // robustness
1593 }
1594 // Worst case we need old_cp->length() + scratch_cp()->length(),
1595 // but the caller might be smart so make sure we have at least
1596 // the minimum.
1597 if ((*merge_cp_p)->length() < old_cp->length()) {
1598 assert(false, "merge area too small");
1599 return false; // robustness
1600 }
1601
1602 log_info(redefine, class, constantpool)("old_cp_len=%d, scratch_cp_len=%d", old_cp->length(), scratch_cp->length());
1603
1604 {
1605 // Pass 0:
1606 // The old_cp is copied to *merge_cp_p; this means that any code
1607 // using old_cp does not have to change. This work looks like a
1608 // perfect fit for ConstantPool*::copy_cp_to(), but we need to
1609 // handle one special case:
1610 // - revert JVM_CONSTANT_Class to JVM_CONSTANT_UnresolvedClass
1611 // This will make verification happy.
1612
1613 int old_i; // index into old_cp
1614
1615 // index zero (0) is not used in constantPools
1616 for (old_i = 1; old_i < old_cp->length(); old_i++) {
1617 // leave debugging crumb
1618 jbyte old_tag = old_cp->tag_at(old_i).value();
1619 switch (old_tag) {
1620 case JVM_CONSTANT_Class:
1621 case JVM_CONSTANT_UnresolvedClass:
1622 // revert the copy to JVM_CONSTANT_UnresolvedClass
1623 // May be resolving while calling this so do the same for
1624 // JVM_CONSTANT_UnresolvedClass (klass_name_at() deals with transition)
1625 (*merge_cp_p)->temp_unresolved_klass_at_put(old_i,
1626 old_cp->klass_name_index_at(old_i));
1627 break;
1628
1629 case JVM_CONSTANT_Double:
1630 case JVM_CONSTANT_Long:
1631 // just copy the entry to *merge_cp_p, but double and long take
1632 // two constant pool entries
1633 ConstantPool::copy_entry_to(old_cp, old_i, *merge_cp_p, old_i);
1634 old_i++;
1635 break;
1636
1637 default:
1638 // just copy the entry to *merge_cp_p
1639 ConstantPool::copy_entry_to(old_cp, old_i, *merge_cp_p, old_i);
1640 break;
1641 }
1642 } // end for each old_cp entry
1643
1644 ConstantPool::copy_operands(old_cp, *merge_cp_p, CHECK_false);
1645 (*merge_cp_p)->extend_operands(scratch_cp, CHECK_false);
1646
1647 // We don't need to sanity check that *merge_cp_length_p is within
1648 // *merge_cp_p bounds since we have the minimum on-entry check above.
1649 (*merge_cp_length_p) = old_i;
1650 }
1651
1652 // merge_cp_len should be the same as old_cp->length() at this point
1653 // so this trace message is really a "warm-and-breathing" message.
1654 log_debug(redefine, class, constantpool)("after pass 0: merge_cp_len=%d", *merge_cp_length_p);
1655
1656 int scratch_i; // index into scratch_cp
1657 {
1658 // Pass 1a:
1659 // Compare scratch_cp entries to the old_cp entries that we have
1660 // already copied to *merge_cp_p. In this pass, we are eliminating
1661 // exact duplicates (matching entry at same index) so we only
1662 // compare entries in the common indice range.
1663 int increment = 1;
1664 int pass1a_length = MIN2(old_cp->length(), scratch_cp->length());
1665 for (scratch_i = 1; scratch_i < pass1a_length; scratch_i += increment) {
1666 switch (scratch_cp->tag_at(scratch_i).value()) {
1667 case JVM_CONSTANT_Double:
1668 case JVM_CONSTANT_Long:
1669 // double and long take two constant pool entries
1670 increment = 2;
1671 break;
1672
1673 default:
1674 increment = 1;
1675 break;
1676 }
1677
1678 bool match = scratch_cp->compare_entry_to(scratch_i, *merge_cp_p, scratch_i);
1679 if (match) {
1680 // found a match at the same index so nothing more to do
1681 continue;
1682 }
1683
1684 int found_i = scratch_cp->find_matching_entry(scratch_i, *merge_cp_p);
1685 if (found_i != 0) {
1686 guarantee(found_i != scratch_i,
1687 "compare_entry_to() and find_matching_entry() do not agree");
1688
1689 // Found a matching entry somewhere else in *merge_cp_p so
1690 // just need a mapping entry.
1691 map_index(scratch_cp, scratch_i, found_i);
1692 continue;
1693 }
1694
1695 // No match found so we have to append this entry and any unique
1696 // referenced entries to *merge_cp_p.
1697 append_entry(scratch_cp, scratch_i, merge_cp_p, merge_cp_length_p);
1698 }
1699 }
1700
1701 log_debug(redefine, class, constantpool)
1702 ("after pass 1a: merge_cp_len=%d, scratch_i=%d, index_map_len=%d",
1703 *merge_cp_length_p, scratch_i, _index_map_count);
1704
1705 if (scratch_i < scratch_cp->length()) {
1706 // Pass 1b:
1707 // old_cp is smaller than scratch_cp so there are entries in
1708 // scratch_cp that we have not yet processed. We take care of
1709 // those now.
1710 int increment = 1;
1711 for (; scratch_i < scratch_cp->length(); scratch_i += increment) {
1712 switch (scratch_cp->tag_at(scratch_i).value()) {
1713 case JVM_CONSTANT_Double:
1714 case JVM_CONSTANT_Long:
1715 // double and long take two constant pool entries
1716 increment = 2;
1717 break;
1718
1719 default:
1720 increment = 1;
1721 break;
1722 }
1723
1724 int found_i =
1725 scratch_cp->find_matching_entry(scratch_i, *merge_cp_p);
1726 if (found_i != 0) {
1727 // Found a matching entry somewhere else in *merge_cp_p so
1728 // just need a mapping entry.
1729 map_index(scratch_cp, scratch_i, found_i);
1730 continue;
1731 }
1732
1733 // No match found so we have to append this entry and any unique
1734 // referenced entries to *merge_cp_p.
1735 append_entry(scratch_cp, scratch_i, merge_cp_p, merge_cp_length_p);
1736 }
1737
1738 log_debug(redefine, class, constantpool)
1739 ("after pass 1b: merge_cp_len=%d, scratch_i=%d, index_map_len=%d",
1740 *merge_cp_length_p, scratch_i, _index_map_count);
1741 }
1742 finalize_operands_merge(*merge_cp_p, CHECK_false);
1743
1744 return true;
1745 } // end merge_constant_pools()
1746
1747
1748 // Scoped object to clean up the constant pool(s) created for merging
1749 class MergeCPCleaner {
1750 ClassLoaderData* _loader_data;
1751 ConstantPool* _cp;
1752 ConstantPool* _scratch_cp;
1753 public:
1754 MergeCPCleaner(ClassLoaderData* loader_data, ConstantPool* merge_cp) :
1755 _loader_data(loader_data), _cp(merge_cp), _scratch_cp(nullptr) {}
1756 ~MergeCPCleaner() {
1757 _loader_data->add_to_deallocate_list(_cp);
1758 if (_scratch_cp != nullptr) {
1759 _loader_data->add_to_deallocate_list(_scratch_cp);
1760 }
1761 }
1762 void add_scratch_cp(ConstantPool* scratch_cp) { _scratch_cp = scratch_cp; }
1763 };
1764
1765 // Merge constant pools between the_class and scratch_class and
1766 // potentially rewrite bytecodes in scratch_class to use the merged
1767 // constant pool.
1768 jvmtiError VM_RedefineClasses::merge_cp_and_rewrite(
1769 InstanceKlass* the_class, InstanceKlass* scratch_class,
1770 TRAPS) {
1771 // worst case merged constant pool length is old and new combined
1772 int merge_cp_length = the_class->constants()->length()
1773 + scratch_class->constants()->length();
1774
1775 // Constant pools are not easily reused so we allocate a new one
1776 // each time.
1777 // merge_cp is created unsafe for concurrent GC processing. It
1778 // should be marked safe before discarding it. Even though
1779 // garbage, if it crosses a card boundary, it may be scanned
1780 // in order to find the start of the first complete object on the card.
1781 ClassLoaderData* loader_data = the_class->class_loader_data();
1782 ConstantPool* merge_cp_oop =
1783 ConstantPool::allocate(loader_data,
1784 merge_cp_length,
1785 CHECK_(JVMTI_ERROR_OUT_OF_MEMORY));
1786 MergeCPCleaner cp_cleaner(loader_data, merge_cp_oop);
1787
1788 HandleMark hm(THREAD); // make sure handles are cleared before
1789 // MergeCPCleaner clears out merge_cp_oop
1790 constantPoolHandle merge_cp(THREAD, merge_cp_oop);
1791
1792 // Get constants() from the old class because it could have been rewritten
1793 // while we were at a safepoint allocating a new constant pool.
1794 constantPoolHandle old_cp(THREAD, the_class->constants());
1795 constantPoolHandle scratch_cp(THREAD, scratch_class->constants());
1796
1797 // If the length changed, the class was redefined out from under us. Return
1798 // an error.
1799 if (merge_cp_length != the_class->constants()->length()
1800 + scratch_class->constants()->length()) {
1801 return JVMTI_ERROR_INTERNAL;
1802 }
1803
1804 // Update the version number of the constant pools (may keep scratch_cp)
1805 merge_cp->increment_and_save_version(old_cp->version());
1806 scratch_cp->increment_and_save_version(old_cp->version());
1807
1808 ResourceMark rm(THREAD);
1809 _index_map_count = 0;
1810 _index_map_p = new intArray(scratch_cp->length(), scratch_cp->length(), -1);
1811
1812 _operands_cur_length = ConstantPool::operand_array_length(old_cp->operands());
1813 _operands_index_map_count = 0;
1814 int operands_index_map_len = ConstantPool::operand_array_length(scratch_cp->operands());
1815 _operands_index_map_p = new intArray(operands_index_map_len, operands_index_map_len, -1);
1816
1817 // reference to the cp holder is needed for copy_operands()
1818 merge_cp->set_pool_holder(scratch_class);
1819 bool result = merge_constant_pools(old_cp, scratch_cp, &merge_cp,
1820 &merge_cp_length, THREAD);
1821 merge_cp->set_pool_holder(nullptr);
1822
1823 if (!result) {
1824 // The merge can fail due to memory allocation failure or due
1825 // to robustness checks.
1826 return JVMTI_ERROR_INTERNAL;
1827 }
1828
1829 // ensure merged constant pool size does not overflow u2
1830 if (merge_cp_length > 0xFFFF) {
1831 log_warning(redefine, class, constantpool)("Merged constant pool overflow: %d entries", merge_cp_length);
1832 return JVMTI_ERROR_INTERNAL;
1833 }
1834
1835 // Set dynamic constants attribute from the original CP.
1836 if (old_cp->has_dynamic_constant()) {
1837 scratch_cp->set_has_dynamic_constant();
1838 }
1839
1840 log_info(redefine, class, constantpool)("merge_cp_len=%d, index_map_len=%d", merge_cp_length, _index_map_count);
1841
1842 if (_index_map_count == 0) {
1843 // there is nothing to map between the new and merged constant pools
1844
1845 // Copy attributes from scratch_cp to merge_cp
1846 merge_cp->copy_fields(scratch_cp());
1847
1848 if (old_cp->length() == scratch_cp->length()) {
1849 // The old and new constant pools are the same length and the
1850 // index map is empty. This means that the three constant pools
1851 // are equivalent (but not the same). Unfortunately, the new
1852 // constant pool has not gone through link resolution nor have
1853 // the new class bytecodes gone through constant pool cache
1854 // rewriting so we can't use the old constant pool with the new
1855 // class.
1856
1857 // toss the merged constant pool at return
1858 } else if (old_cp->length() < scratch_cp->length()) {
1859 // The old constant pool has fewer entries than the new constant
1860 // pool and the index map is empty. This means the new constant
1861 // pool is a superset of the old constant pool. However, the old
1862 // class bytecodes have already gone through constant pool cache
1863 // rewriting so we can't use the new constant pool with the old
1864 // class.
1865
1866 // toss the merged constant pool at return
1867 } else {
1868 // The old constant pool has more entries than the new constant
1869 // pool and the index map is empty. This means that both the old
1870 // and merged constant pools are supersets of the new constant
1871 // pool.
1872
1873 // Replace the new constant pool with a shrunken copy of the
1874 // merged constant pool
1875 set_new_constant_pool(loader_data, scratch_class, merge_cp, merge_cp_length,
1876 CHECK_(JVMTI_ERROR_OUT_OF_MEMORY));
1877 // The new constant pool replaces scratch_cp so have cleaner clean it up.
1878 // It can't be cleaned up while there are handles to it.
1879 cp_cleaner.add_scratch_cp(scratch_cp());
1880 }
1881 } else {
1882 if (log_is_enabled(Trace, redefine, class, constantpool)) {
1883 // don't want to loop unless we are tracing
1884 int count = 0;
1885 for (int i = 1; i < _index_map_p->length(); i++) {
1886 int value = _index_map_p->at(i);
1887
1888 if (value != -1) {
1889 log_trace(redefine, class, constantpool)("index_map[%d]: old=%d new=%d", count, i, value);
1890 count++;
1891 }
1892 }
1893 }
1894
1895 // We have entries mapped between the new and merged constant pools
1896 // so we have to rewrite some constant pool references.
1897 if (!rewrite_cp_refs(scratch_class)) {
1898 return JVMTI_ERROR_INTERNAL;
1899 }
1900
1901 // Copy attributes from scratch_cp to merge_cp (should be done after rewrite_cp_refs())
1902 merge_cp->copy_fields(scratch_cp());
1903
1904 // Replace the new constant pool with a shrunken copy of the
1905 // merged constant pool so now the rewritten bytecodes have
1906 // valid references; the previous new constant pool will get
1907 // GCed.
1908 set_new_constant_pool(loader_data, scratch_class, merge_cp, merge_cp_length,
1909 CHECK_(JVMTI_ERROR_OUT_OF_MEMORY));
1910 // The new constant pool replaces scratch_cp so have cleaner clean it up.
1911 // It can't be cleaned up while there are handles to it.
1912 cp_cleaner.add_scratch_cp(scratch_cp());
1913 }
1914
1915 return JVMTI_ERROR_NONE;
1916 } // end merge_cp_and_rewrite()
1917
1918
1919 // Rewrite constant pool references in klass scratch_class.
1920 bool VM_RedefineClasses::rewrite_cp_refs(InstanceKlass* scratch_class) {
1921
1922 // rewrite constant pool references in the nest attributes:
1923 if (!rewrite_cp_refs_in_nest_attributes(scratch_class)) {
1924 // propagate failure back to caller
1925 return false;
1926 }
1927
1928 // rewrite constant pool references in the Record attribute:
1929 if (!rewrite_cp_refs_in_record_attribute(scratch_class)) {
1930 // propagate failure back to caller
1931 return false;
1932 }
1933
1934 // rewrite constant pool references in the PermittedSubclasses attribute:
1935 if (!rewrite_cp_refs_in_permitted_subclasses_attribute(scratch_class)) {
1936 // propagate failure back to caller
1937 return false;
1938 }
1939
1940 // rewrite constant pool references in the LoadableDescriptors attribute:
1941 if (!rewrite_cp_refs_in_loadable_descriptors_attribute(scratch_class)) {
1942 // propagate failure back to caller
1943 return false;
1944 }
1945
1946 // rewrite constant pool references in the methods:
1947 if (!rewrite_cp_refs_in_methods(scratch_class)) {
1948 // propagate failure back to caller
1949 return false;
1950 }
1951
1952 // rewrite constant pool references in the class_annotations:
1953 if (!rewrite_cp_refs_in_class_annotations(scratch_class)) {
1954 // propagate failure back to caller
1955 return false;
1956 }
1957
1958 // rewrite constant pool references in the fields_annotations:
1959 if (!rewrite_cp_refs_in_fields_annotations(scratch_class)) {
1960 // propagate failure back to caller
1961 return false;
1962 }
1963
1964 // rewrite constant pool references in the methods_annotations:
1965 if (!rewrite_cp_refs_in_methods_annotations(scratch_class)) {
1966 // propagate failure back to caller
1967 return false;
1968 }
1969
1970 // rewrite constant pool references in the methods_parameter_annotations:
1971 if (!rewrite_cp_refs_in_methods_parameter_annotations(scratch_class)) {
1972 // propagate failure back to caller
1973 return false;
1974 }
1975
1976 // rewrite constant pool references in the methods_default_annotations:
1977 if (!rewrite_cp_refs_in_methods_default_annotations(scratch_class)) {
1978 // propagate failure back to caller
1979 return false;
1980 }
1981
1982 // rewrite constant pool references in the class_type_annotations:
1983 if (!rewrite_cp_refs_in_class_type_annotations(scratch_class)) {
1984 // propagate failure back to caller
1985 return false;
1986 }
1987
1988 // rewrite constant pool references in the fields_type_annotations:
1989 if (!rewrite_cp_refs_in_fields_type_annotations(scratch_class)) {
1990 // propagate failure back to caller
1991 return false;
1992 }
1993
1994 // rewrite constant pool references in the methods_type_annotations:
1995 if (!rewrite_cp_refs_in_methods_type_annotations(scratch_class)) {
1996 // propagate failure back to caller
1997 return false;
1998 }
1999
2000 // There can be type annotations in the Code part of a method_info attribute.
2001 // These annotations are not accessible, even by reflection.
2002 // Currently they are not even parsed by the ClassFileParser.
2003 // If runtime access is added they will also need to be rewritten.
2004
2005 // rewrite source file name index:
2006 u2 source_file_name_idx = scratch_class->source_file_name_index();
2007 if (source_file_name_idx != 0) {
2008 u2 new_source_file_name_idx = find_new_index(source_file_name_idx);
2009 if (new_source_file_name_idx != 0) {
2010 scratch_class->set_source_file_name_index(new_source_file_name_idx);
2011 }
2012 }
2013
2014 // rewrite class generic signature index:
2015 u2 generic_signature_index = scratch_class->generic_signature_index();
2016 if (generic_signature_index != 0) {
2017 u2 new_generic_signature_index = find_new_index(generic_signature_index);
2018 if (new_generic_signature_index != 0) {
2019 scratch_class->set_generic_signature_index(new_generic_signature_index);
2020 }
2021 }
2022
2023 return true;
2024 } // end rewrite_cp_refs()
2025
2026 // Rewrite constant pool references in the NestHost and NestMembers attributes.
2027 bool VM_RedefineClasses::rewrite_cp_refs_in_nest_attributes(
2028 InstanceKlass* scratch_class) {
2029
2030 u2 cp_index = scratch_class->nest_host_index();
2031 if (cp_index != 0) {
2032 scratch_class->set_nest_host_index(find_new_index(cp_index));
2033 }
2034 Array<u2>* nest_members = scratch_class->nest_members();
2035 for (int i = 0; i < nest_members->length(); i++) {
2036 u2 cp_index = nest_members->at(i);
2037 nest_members->at_put(i, find_new_index(cp_index));
2038 }
2039 return true;
2040 }
2041
2042 // Rewrite constant pool references in the Record attribute.
2043 bool VM_RedefineClasses::rewrite_cp_refs_in_record_attribute(InstanceKlass* scratch_class) {
2044 Array<RecordComponent*>* components = scratch_class->record_components();
2045 if (components != nullptr) {
2046 for (int i = 0; i < components->length(); i++) {
2047 RecordComponent* component = components->at(i);
2048 u2 cp_index = component->name_index();
2049 component->set_name_index(find_new_index(cp_index));
2050 cp_index = component->descriptor_index();
2051 component->set_descriptor_index(find_new_index(cp_index));
2052 cp_index = component->generic_signature_index();
2053 if (cp_index != 0) {
2054 component->set_generic_signature_index(find_new_index(cp_index));
2055 }
2056
2057 AnnotationArray* annotations = component->annotations();
2058 if (annotations != nullptr && annotations->length() != 0) {
2059 int byte_i = 0; // byte index into annotations
2060 if (!rewrite_cp_refs_in_annotations_typeArray(annotations, byte_i)) {
2061 log_debug(redefine, class, annotation)("bad record_component_annotations at %d", i);
2062 // propagate failure back to caller
2063 return false;
2064 }
2065 }
2066
2067 AnnotationArray* type_annotations = component->type_annotations();
2068 if (type_annotations != nullptr && type_annotations->length() != 0) {
2069 int byte_i = 0; // byte index into annotations
2070 if (!rewrite_cp_refs_in_annotations_typeArray(type_annotations, byte_i)) {
2071 log_debug(redefine, class, annotation)("bad record_component_type_annotations at %d", i);
2072 // propagate failure back to caller
2073 return false;
2074 }
2075 }
2076 }
2077 }
2078 return true;
2079 }
2080
2081 // Rewrite constant pool references in the PermittedSubclasses attribute.
2082 bool VM_RedefineClasses::rewrite_cp_refs_in_permitted_subclasses_attribute(
2083 InstanceKlass* scratch_class) {
2084
2085 Array<u2>* permitted_subclasses = scratch_class->permitted_subclasses();
2086 assert(permitted_subclasses != nullptr, "unexpected null permitted_subclasses");
2087 for (int i = 0; i < permitted_subclasses->length(); i++) {
2088 u2 cp_index = permitted_subclasses->at(i);
2089 permitted_subclasses->at_put(i, find_new_index(cp_index));
2090 }
2091 return true;
2092 }
2093
2094 // Rewrite constant pool references in the LoadableDescriptors attribute.
2095 bool VM_RedefineClasses::rewrite_cp_refs_in_loadable_descriptors_attribute(
2096 InstanceKlass* scratch_class) {
2097
2098 Array<u2>* loadable_descriptors = scratch_class->loadable_descriptors();
2099 assert(loadable_descriptors != nullptr, "unexpected null loadable_descriptors");
2100 for (int i = 0; i < loadable_descriptors->length(); i++) {
2101 u2 cp_index = loadable_descriptors->at(i);
2102 loadable_descriptors->at_put(i, find_new_index(cp_index));
2103 }
2104 return true;
2105 }
2106
2107 // Rewrite constant pool references in the methods.
2108 bool VM_RedefineClasses::rewrite_cp_refs_in_methods(InstanceKlass* scratch_class) {
2109
2110 Array<Method*>* methods = scratch_class->methods();
2111
2112 if (methods == nullptr || methods->length() == 0) {
2113 // no methods so nothing to do
2114 return true;
2115 }
2116
2117 JavaThread* THREAD = JavaThread::current(); // For exception macros.
2118 ExceptionMark em(THREAD);
2119
2120 // rewrite constant pool references in the methods:
2121 for (int i = methods->length() - 1; i >= 0; i--) {
2122 methodHandle method(THREAD, methods->at(i));
2123 methodHandle new_method;
2124 rewrite_cp_refs_in_method(method, &new_method, THREAD);
2125 if (!new_method.is_null()) {
2126 // the method has been replaced so save the new method version
2127 // even in the case of an exception. original method is on the
2128 // deallocation list.
2129 methods->at_put(i, new_method());
2130 }
2131 if (HAS_PENDING_EXCEPTION) {
2132 Symbol* ex_name = PENDING_EXCEPTION->klass()->name();
2133 log_info(redefine, class, load, exceptions)("rewrite_cp_refs_in_method exception: '%s'", ex_name->as_C_string());
2134 // Need to clear pending exception here as the super caller sets
2135 // the JVMTI_ERROR_INTERNAL if the returned value is false.
2136 CLEAR_PENDING_EXCEPTION;
2137 return false;
2138 }
2139 }
2140
2141 return true;
2142 }
2143
2144
2145 // Rewrite constant pool references in the specific method. This code
2146 // was adapted from Rewriter::rewrite_method().
2147 void VM_RedefineClasses::rewrite_cp_refs_in_method(methodHandle method,
2148 methodHandle *new_method_p, TRAPS) {
2149
2150 *new_method_p = methodHandle(); // default is no new method
2151
2152 // We cache a pointer to the bytecodes here in code_base. If GC
2153 // moves the Method*, then the bytecodes will also move which
2154 // will likely cause a crash. We create a NoSafepointVerifier
2155 // object to detect whether we pass a possible safepoint in this
2156 // code block.
2157 NoSafepointVerifier nsv;
2158
2159 // Bytecodes and their length
2160 address code_base = method->code_base();
2161 int code_length = method->code_size();
2162
2163 int bc_length;
2164 for (int bci = 0; bci < code_length; bci += bc_length) {
2165 address bcp = code_base + bci;
2166 Bytecodes::Code c = (Bytecodes::Code)(*bcp);
2167
2168 bc_length = Bytecodes::length_for(c);
2169 if (bc_length == 0) {
2170 // More complicated bytecodes report a length of zero so
2171 // we have to try again a slightly different way.
2172 bc_length = Bytecodes::length_at(method(), bcp);
2173 }
2174
2175 assert(bc_length != 0, "impossible bytecode length");
2176
2177 switch (c) {
2178 case Bytecodes::_ldc:
2179 {
2180 u1 cp_index = *(bcp + 1);
2181 u2 new_index = find_new_index(cp_index);
2182
2183 if (StressLdcRewrite && new_index == 0) {
2184 // If we are stressing ldc -> ldc_w rewriting, then we
2185 // always need a new_index value.
2186 new_index = cp_index;
2187 }
2188 if (new_index != 0) {
2189 // the original index is mapped so we have more work to do
2190 if (!StressLdcRewrite && new_index <= max_jubyte) {
2191 // The new value can still use ldc instead of ldc_w
2192 // unless we are trying to stress ldc -> ldc_w rewriting
2193 log_trace(redefine, class, constantpool)
2194 ("%s@" INTPTR_FORMAT " old=%d, new=%d", Bytecodes::name(c), p2i(bcp), cp_index, new_index);
2195 // We checked that new_index fits in a u1 so this cast is safe
2196 *(bcp + 1) = (u1)new_index;
2197 } else {
2198 log_trace(redefine, class, constantpool)
2199 ("%s->ldc_w@" INTPTR_FORMAT " old=%d, new=%d", Bytecodes::name(c), p2i(bcp), cp_index, new_index);
2200 // the new value needs ldc_w instead of ldc
2201 u_char inst_buffer[4]; // max instruction size is 4 bytes
2202 bcp = (address)inst_buffer;
2203 // construct new instruction sequence
2204 *bcp = Bytecodes::_ldc_w;
2205 bcp++;
2206 // Rewriter::rewrite_method() does not rewrite ldc -> ldc_w.
2207 // See comment below for difference between put_Java_u2()
2208 // and put_native_u2().
2209 Bytes::put_Java_u2(bcp, new_index);
2210
2211 Relocator rc(method, nullptr /* no RelocatorListener needed */);
2212 methodHandle m;
2213 {
2214 PauseNoSafepointVerifier pnsv(&nsv);
2215
2216 // ldc is 2 bytes and ldc_w is 3 bytes
2217 m = rc.insert_space_at(bci, 3, inst_buffer, CHECK);
2218 }
2219
2220 // return the new method so that the caller can update
2221 // the containing class
2222 *new_method_p = method = m;
2223 // switch our bytecode processing loop from the old method
2224 // to the new method
2225 code_base = method->code_base();
2226 code_length = method->code_size();
2227 bcp = code_base + bci;
2228 c = (Bytecodes::Code)(*bcp);
2229 bc_length = Bytecodes::length_for(c);
2230 assert(bc_length != 0, "sanity check");
2231 } // end we need ldc_w instead of ldc
2232 } // end if there is a mapped index
2233 } break;
2234
2235 // these bytecodes have a two-byte constant pool index
2236 case Bytecodes::_anewarray : // fall through
2237 case Bytecodes::_checkcast : // fall through
2238 case Bytecodes::_getfield : // fall through
2239 case Bytecodes::_getstatic : // fall through
2240 case Bytecodes::_instanceof : // fall through
2241 case Bytecodes::_invokedynamic : // fall through
2242 case Bytecodes::_invokeinterface: // fall through
2243 case Bytecodes::_invokespecial : // fall through
2244 case Bytecodes::_invokestatic : // fall through
2245 case Bytecodes::_invokevirtual : // fall through
2246 case Bytecodes::_ldc_w : // fall through
2247 case Bytecodes::_ldc2_w : // fall through
2248 case Bytecodes::_multianewarray : // fall through
2249 case Bytecodes::_new : // fall through
2250 case Bytecodes::_putfield : // fall through
2251 case Bytecodes::_putstatic :
2252 {
2253 address p = bcp + 1;
2254 int cp_index = Bytes::get_Java_u2(p);
2255 u2 new_index = find_new_index(cp_index);
2256 if (new_index != 0) {
2257 // the original index is mapped so update w/ new value
2258 log_trace(redefine, class, constantpool)
2259 ("%s@" INTPTR_FORMAT " old=%d, new=%d", Bytecodes::name(c),p2i(bcp), cp_index, new_index);
2260 // Rewriter::rewrite_method() uses put_native_u2() in this
2261 // situation because it is reusing the constant pool index
2262 // location for a native index into the ConstantPoolCache.
2263 // Since we are updating the constant pool index prior to
2264 // verification and ConstantPoolCache initialization, we
2265 // need to keep the new index in Java byte order.
2266 Bytes::put_Java_u2(p, new_index);
2267 }
2268 } break;
2269 default:
2270 break;
2271 }
2272 } // end for each bytecode
2273 } // end rewrite_cp_refs_in_method()
2274
2275
2276 // Rewrite constant pool references in the class_annotations field.
2277 bool VM_RedefineClasses::rewrite_cp_refs_in_class_annotations(InstanceKlass* scratch_class) {
2278
2279 AnnotationArray* class_annotations = scratch_class->class_annotations();
2280 if (class_annotations == nullptr || class_annotations->length() == 0) {
2281 // no class_annotations so nothing to do
2282 return true;
2283 }
2284
2285 log_debug(redefine, class, annotation)("class_annotations length=%d", class_annotations->length());
2286
2287 int byte_i = 0; // byte index into class_annotations
2288 return rewrite_cp_refs_in_annotations_typeArray(class_annotations, byte_i);
2289 }
2290
2291
2292 // Rewrite constant pool references in an annotations typeArray. This
2293 // "structure" is adapted from the RuntimeVisibleAnnotations_attribute
2294 // that is described in section 4.8.15 of the 2nd-edition of the VM spec:
2295 //
2296 // annotations_typeArray {
2297 // u2 num_annotations;
2298 // annotation annotations[num_annotations];
2299 // }
2300 //
2301 bool VM_RedefineClasses::rewrite_cp_refs_in_annotations_typeArray(
2302 AnnotationArray* annotations_typeArray, int &byte_i_ref) {
2303
2304 if ((byte_i_ref + 2) > annotations_typeArray->length()) {
2305 // not enough room for num_annotations field
2306 log_debug(redefine, class, annotation)("length() is too small for num_annotations field");
2307 return false;
2308 }
2309
2310 u2 num_annotations = Bytes::get_Java_u2((address)
2311 annotations_typeArray->adr_at(byte_i_ref));
2312 byte_i_ref += 2;
2313
2314 log_debug(redefine, class, annotation)("num_annotations=%d", num_annotations);
2315
2316 int calc_num_annotations = 0;
2317 for (; calc_num_annotations < num_annotations; calc_num_annotations++) {
2318 if (!rewrite_cp_refs_in_annotation_struct(annotations_typeArray, byte_i_ref)) {
2319 log_debug(redefine, class, annotation)("bad annotation_struct at %d", calc_num_annotations);
2320 // propagate failure back to caller
2321 return false;
2322 }
2323 }
2324 assert(num_annotations == calc_num_annotations, "sanity check");
2325
2326 return true;
2327 } // end rewrite_cp_refs_in_annotations_typeArray()
2328
2329
2330 // Rewrite constant pool references in the annotation struct portion of
2331 // an annotations_typeArray. This "structure" is from section 4.8.15 of
2332 // the 2nd-edition of the VM spec:
2333 //
2334 // struct annotation {
2335 // u2 type_index;
2336 // u2 num_element_value_pairs;
2337 // {
2338 // u2 element_name_index;
2339 // element_value value;
2340 // } element_value_pairs[num_element_value_pairs];
2341 // }
2342 //
2343 bool VM_RedefineClasses::rewrite_cp_refs_in_annotation_struct(
2344 AnnotationArray* annotations_typeArray, int &byte_i_ref) {
2345 if ((byte_i_ref + 2 + 2) > annotations_typeArray->length()) {
2346 // not enough room for smallest annotation_struct
2347 log_debug(redefine, class, annotation)("length() is too small for annotation_struct");
2348 return false;
2349 }
2350
2351 u2 type_index = rewrite_cp_ref_in_annotation_data(annotations_typeArray,
2352 byte_i_ref, "type_index");
2353
2354 u2 num_element_value_pairs = Bytes::get_Java_u2((address)
2355 annotations_typeArray->adr_at(byte_i_ref));
2356 byte_i_ref += 2;
2357
2358 log_debug(redefine, class, annotation)
2359 ("type_index=%d num_element_value_pairs=%d", type_index, num_element_value_pairs);
2360
2361 int calc_num_element_value_pairs = 0;
2362 for (; calc_num_element_value_pairs < num_element_value_pairs;
2363 calc_num_element_value_pairs++) {
2364 if ((byte_i_ref + 2) > annotations_typeArray->length()) {
2365 // not enough room for another element_name_index, let alone
2366 // the rest of another component
2367 log_debug(redefine, class, annotation)("length() is too small for element_name_index");
2368 return false;
2369 }
2370
2371 u2 element_name_index = rewrite_cp_ref_in_annotation_data(
2372 annotations_typeArray, byte_i_ref,
2373 "element_name_index");
2374
2375 log_debug(redefine, class, annotation)("element_name_index=%d", element_name_index);
2376
2377 if (!rewrite_cp_refs_in_element_value(annotations_typeArray, byte_i_ref)) {
2378 log_debug(redefine, class, annotation)("bad element_value at %d", calc_num_element_value_pairs);
2379 // propagate failure back to caller
2380 return false;
2381 }
2382 } // end for each component
2383 assert(num_element_value_pairs == calc_num_element_value_pairs,
2384 "sanity check");
2385
2386 return true;
2387 } // end rewrite_cp_refs_in_annotation_struct()
2388
2389
2390 // Rewrite a constant pool reference at the current position in
2391 // annotations_typeArray if needed. Returns the original constant
2392 // pool reference if a rewrite was not needed or the new constant
2393 // pool reference if a rewrite was needed.
2394 u2 VM_RedefineClasses::rewrite_cp_ref_in_annotation_data(
2395 AnnotationArray* annotations_typeArray, int &byte_i_ref,
2396 const char * trace_mesg) {
2397
2398 address cp_index_addr = (address)
2399 annotations_typeArray->adr_at(byte_i_ref);
2400 u2 old_cp_index = Bytes::get_Java_u2(cp_index_addr);
2401 u2 new_cp_index = find_new_index(old_cp_index);
2402 if (new_cp_index != 0) {
2403 log_debug(redefine, class, annotation)("mapped old %s=%d", trace_mesg, old_cp_index);
2404 Bytes::put_Java_u2(cp_index_addr, new_cp_index);
2405 old_cp_index = new_cp_index;
2406 }
2407 byte_i_ref += 2;
2408 return old_cp_index;
2409 }
2410
2411
2412 // Rewrite constant pool references in the element_value portion of an
2413 // annotations_typeArray. This "structure" is from section 4.8.15.1 of
2414 // the 2nd-edition of the VM spec:
2415 //
2416 // struct element_value {
2417 // u1 tag;
2418 // union {
2419 // u2 const_value_index;
2420 // {
2421 // u2 type_name_index;
2422 // u2 const_name_index;
2423 // } enum_const_value;
2424 // u2 class_info_index;
2425 // annotation annotation_value;
2426 // struct {
2427 // u2 num_values;
2428 // element_value values[num_values];
2429 // } array_value;
2430 // } value;
2431 // }
2432 //
2433 bool VM_RedefineClasses::rewrite_cp_refs_in_element_value(
2434 AnnotationArray* annotations_typeArray, int &byte_i_ref) {
2435
2436 if ((byte_i_ref + 1) > annotations_typeArray->length()) {
2437 // not enough room for a tag let alone the rest of an element_value
2438 log_debug(redefine, class, annotation)("length() is too small for a tag");
2439 return false;
2440 }
2441
2442 u1 tag = annotations_typeArray->at(byte_i_ref);
2443 byte_i_ref++;
2444 log_debug(redefine, class, annotation)("tag='%c'", tag);
2445
2446 switch (tag) {
2447 // These BaseType tag values are from Table 4.2 in VM spec:
2448 case JVM_SIGNATURE_BYTE:
2449 case JVM_SIGNATURE_CHAR:
2450 case JVM_SIGNATURE_DOUBLE:
2451 case JVM_SIGNATURE_FLOAT:
2452 case JVM_SIGNATURE_INT:
2453 case JVM_SIGNATURE_LONG:
2454 case JVM_SIGNATURE_SHORT:
2455 case JVM_SIGNATURE_BOOLEAN:
2456
2457 // The remaining tag values are from Table 4.8 in the 2nd-edition of
2458 // the VM spec:
2459 case 's':
2460 {
2461 // For the above tag values (including the BaseType values),
2462 // value.const_value_index is right union field.
2463
2464 if ((byte_i_ref + 2) > annotations_typeArray->length()) {
2465 // not enough room for a const_value_index
2466 log_debug(redefine, class, annotation)("length() is too small for a const_value_index");
2467 return false;
2468 }
2469
2470 u2 const_value_index = rewrite_cp_ref_in_annotation_data(
2471 annotations_typeArray, byte_i_ref,
2472 "const_value_index");
2473
2474 log_debug(redefine, class, annotation)("const_value_index=%d", const_value_index);
2475 } break;
2476
2477 case 'e':
2478 {
2479 // for the above tag value, value.enum_const_value is right union field
2480
2481 if ((byte_i_ref + 4) > annotations_typeArray->length()) {
2482 // not enough room for a enum_const_value
2483 log_debug(redefine, class, annotation)("length() is too small for a enum_const_value");
2484 return false;
2485 }
2486
2487 u2 type_name_index = rewrite_cp_ref_in_annotation_data(
2488 annotations_typeArray, byte_i_ref,
2489 "type_name_index");
2490
2491 u2 const_name_index = rewrite_cp_ref_in_annotation_data(
2492 annotations_typeArray, byte_i_ref,
2493 "const_name_index");
2494
2495 log_debug(redefine, class, annotation)
2496 ("type_name_index=%d const_name_index=%d", type_name_index, const_name_index);
2497 } break;
2498
2499 case 'c':
2500 {
2501 // for the above tag value, value.class_info_index is right union field
2502
2503 if ((byte_i_ref + 2) > annotations_typeArray->length()) {
2504 // not enough room for a class_info_index
2505 log_debug(redefine, class, annotation)("length() is too small for a class_info_index");
2506 return false;
2507 }
2508
2509 u2 class_info_index = rewrite_cp_ref_in_annotation_data(
2510 annotations_typeArray, byte_i_ref,
2511 "class_info_index");
2512
2513 log_debug(redefine, class, annotation)("class_info_index=%d", class_info_index);
2514 } break;
2515
2516 case '@':
2517 // For the above tag value, value.attr_value is the right union
2518 // field. This is a nested annotation.
2519 if (!rewrite_cp_refs_in_annotation_struct(annotations_typeArray, byte_i_ref)) {
2520 // propagate failure back to caller
2521 return false;
2522 }
2523 break;
2524
2525 case JVM_SIGNATURE_ARRAY:
2526 {
2527 if ((byte_i_ref + 2) > annotations_typeArray->length()) {
2528 // not enough room for a num_values field
2529 log_debug(redefine, class, annotation)("length() is too small for a num_values field");
2530 return false;
2531 }
2532
2533 // For the above tag value, value.array_value is the right union
2534 // field. This is an array of nested element_value.
2535 u2 num_values = Bytes::get_Java_u2((address)
2536 annotations_typeArray->adr_at(byte_i_ref));
2537 byte_i_ref += 2;
2538 log_debug(redefine, class, annotation)("num_values=%d", num_values);
2539
2540 int calc_num_values = 0;
2541 for (; calc_num_values < num_values; calc_num_values++) {
2542 if (!rewrite_cp_refs_in_element_value(annotations_typeArray, byte_i_ref)) {
2543 log_debug(redefine, class, annotation)("bad nested element_value at %d", calc_num_values);
2544 // propagate failure back to caller
2545 return false;
2546 }
2547 }
2548 assert(num_values == calc_num_values, "sanity check");
2549 } break;
2550
2551 default:
2552 log_debug(redefine, class, annotation)("bad tag=0x%x", tag);
2553 return false;
2554 } // end decode tag field
2555
2556 return true;
2557 } // end rewrite_cp_refs_in_element_value()
2558
2559
2560 // Rewrite constant pool references in a fields_annotations field.
2561 bool VM_RedefineClasses::rewrite_cp_refs_in_fields_annotations(
2562 InstanceKlass* scratch_class) {
2563
2564 Array<AnnotationArray*>* fields_annotations = scratch_class->fields_annotations();
2565
2566 if (fields_annotations == nullptr || fields_annotations->length() == 0) {
2567 // no fields_annotations so nothing to do
2568 return true;
2569 }
2570
2571 log_debug(redefine, class, annotation)("fields_annotations length=%d", fields_annotations->length());
2572
2573 for (int i = 0; i < fields_annotations->length(); i++) {
2574 AnnotationArray* field_annotations = fields_annotations->at(i);
2575 if (field_annotations == nullptr || field_annotations->length() == 0) {
2576 // this field does not have any annotations so skip it
2577 continue;
2578 }
2579
2580 int byte_i = 0; // byte index into field_annotations
2581 if (!rewrite_cp_refs_in_annotations_typeArray(field_annotations, byte_i)) {
2582 log_debug(redefine, class, annotation)("bad field_annotations at %d", i);
2583 // propagate failure back to caller
2584 return false;
2585 }
2586 }
2587
2588 return true;
2589 } // end rewrite_cp_refs_in_fields_annotations()
2590
2591
2592 // Rewrite constant pool references in a methods_annotations field.
2593 bool VM_RedefineClasses::rewrite_cp_refs_in_methods_annotations(
2594 InstanceKlass* scratch_class) {
2595
2596 for (int i = 0; i < scratch_class->methods()->length(); i++) {
2597 Method* m = scratch_class->methods()->at(i);
2598 AnnotationArray* method_annotations = m->constMethod()->method_annotations();
2599
2600 if (method_annotations == nullptr || method_annotations->length() == 0) {
2601 // this method does not have any annotations so skip it
2602 continue;
2603 }
2604
2605 int byte_i = 0; // byte index into method_annotations
2606 if (!rewrite_cp_refs_in_annotations_typeArray(method_annotations, byte_i)) {
2607 log_debug(redefine, class, annotation)("bad method_annotations at %d", i);
2608 // propagate failure back to caller
2609 return false;
2610 }
2611 }
2612
2613 return true;
2614 } // end rewrite_cp_refs_in_methods_annotations()
2615
2616
2617 // Rewrite constant pool references in a methods_parameter_annotations
2618 // field. This "structure" is adapted from the
2619 // RuntimeVisibleParameterAnnotations_attribute described in section
2620 // 4.8.17 of the 2nd-edition of the VM spec:
2621 //
2622 // methods_parameter_annotations_typeArray {
2623 // u1 num_parameters;
2624 // {
2625 // u2 num_annotations;
2626 // annotation annotations[num_annotations];
2627 // } parameter_annotations[num_parameters];
2628 // }
2629 //
2630 bool VM_RedefineClasses::rewrite_cp_refs_in_methods_parameter_annotations(
2631 InstanceKlass* scratch_class) {
2632
2633 for (int i = 0; i < scratch_class->methods()->length(); i++) {
2634 Method* m = scratch_class->methods()->at(i);
2635 AnnotationArray* method_parameter_annotations = m->constMethod()->parameter_annotations();
2636 if (method_parameter_annotations == nullptr
2637 || method_parameter_annotations->length() == 0) {
2638 // this method does not have any parameter annotations so skip it
2639 continue;
2640 }
2641
2642 if (method_parameter_annotations->length() < 1) {
2643 // not enough room for a num_parameters field
2644 log_debug(redefine, class, annotation)("length() is too small for a num_parameters field at %d", i);
2645 return false;
2646 }
2647
2648 int byte_i = 0; // byte index into method_parameter_annotations
2649
2650 u1 num_parameters = method_parameter_annotations->at(byte_i);
2651 byte_i++;
2652
2653 log_debug(redefine, class, annotation)("num_parameters=%d", num_parameters);
2654
2655 int calc_num_parameters = 0;
2656 for (; calc_num_parameters < num_parameters; calc_num_parameters++) {
2657 if (!rewrite_cp_refs_in_annotations_typeArray(method_parameter_annotations, byte_i)) {
2658 log_debug(redefine, class, annotation)("bad method_parameter_annotations at %d", calc_num_parameters);
2659 // propagate failure back to caller
2660 return false;
2661 }
2662 }
2663 assert(num_parameters == calc_num_parameters, "sanity check");
2664 }
2665
2666 return true;
2667 } // end rewrite_cp_refs_in_methods_parameter_annotations()
2668
2669
2670 // Rewrite constant pool references in a methods_default_annotations
2671 // field. This "structure" is adapted from the AnnotationDefault_attribute
2672 // that is described in section 4.8.19 of the 2nd-edition of the VM spec:
2673 //
2674 // methods_default_annotations_typeArray {
2675 // element_value default_value;
2676 // }
2677 //
2678 bool VM_RedefineClasses::rewrite_cp_refs_in_methods_default_annotations(
2679 InstanceKlass* scratch_class) {
2680
2681 for (int i = 0; i < scratch_class->methods()->length(); i++) {
2682 Method* m = scratch_class->methods()->at(i);
2683 AnnotationArray* method_default_annotations = m->constMethod()->default_annotations();
2684 if (method_default_annotations == nullptr
2685 || method_default_annotations->length() == 0) {
2686 // this method does not have any default annotations so skip it
2687 continue;
2688 }
2689
2690 int byte_i = 0; // byte index into method_default_annotations
2691
2692 if (!rewrite_cp_refs_in_element_value(
2693 method_default_annotations, byte_i)) {
2694 log_debug(redefine, class, annotation)("bad default element_value at %d", i);
2695 // propagate failure back to caller
2696 return false;
2697 }
2698 }
2699
2700 return true;
2701 } // end rewrite_cp_refs_in_methods_default_annotations()
2702
2703
2704 // Rewrite constant pool references in a class_type_annotations field.
2705 bool VM_RedefineClasses::rewrite_cp_refs_in_class_type_annotations(
2706 InstanceKlass* scratch_class) {
2707
2708 AnnotationArray* class_type_annotations = scratch_class->class_type_annotations();
2709 if (class_type_annotations == nullptr || class_type_annotations->length() == 0) {
2710 // no class_type_annotations so nothing to do
2711 return true;
2712 }
2713
2714 log_debug(redefine, class, annotation)("class_type_annotations length=%d", class_type_annotations->length());
2715
2716 int byte_i = 0; // byte index into class_type_annotations
2717 return rewrite_cp_refs_in_type_annotations_typeArray(class_type_annotations,
2718 byte_i, "ClassFile");
2719 } // end rewrite_cp_refs_in_class_type_annotations()
2720
2721
2722 // Rewrite constant pool references in a fields_type_annotations field.
2723 bool VM_RedefineClasses::rewrite_cp_refs_in_fields_type_annotations(InstanceKlass* scratch_class) {
2724
2725 Array<AnnotationArray*>* fields_type_annotations = scratch_class->fields_type_annotations();
2726 if (fields_type_annotations == nullptr || fields_type_annotations->length() == 0) {
2727 // no fields_type_annotations so nothing to do
2728 return true;
2729 }
2730
2731 log_debug(redefine, class, annotation)("fields_type_annotations length=%d", fields_type_annotations->length());
2732
2733 for (int i = 0; i < fields_type_annotations->length(); i++) {
2734 AnnotationArray* field_type_annotations = fields_type_annotations->at(i);
2735 if (field_type_annotations == nullptr || field_type_annotations->length() == 0) {
2736 // this field does not have any annotations so skip it
2737 continue;
2738 }
2739
2740 int byte_i = 0; // byte index into field_type_annotations
2741 if (!rewrite_cp_refs_in_type_annotations_typeArray(field_type_annotations,
2742 byte_i, "field_info")) {
2743 log_debug(redefine, class, annotation)("bad field_type_annotations at %d", i);
2744 // propagate failure back to caller
2745 return false;
2746 }
2747 }
2748
2749 return true;
2750 } // end rewrite_cp_refs_in_fields_type_annotations()
2751
2752
2753 // Rewrite constant pool references in a methods_type_annotations field.
2754 bool VM_RedefineClasses::rewrite_cp_refs_in_methods_type_annotations(
2755 InstanceKlass* scratch_class) {
2756
2757 for (int i = 0; i < scratch_class->methods()->length(); i++) {
2758 Method* m = scratch_class->methods()->at(i);
2759 AnnotationArray* method_type_annotations = m->constMethod()->type_annotations();
2760
2761 if (method_type_annotations == nullptr || method_type_annotations->length() == 0) {
2762 // this method does not have any annotations so skip it
2763 continue;
2764 }
2765
2766 log_debug(redefine, class, annotation)("methods type_annotations length=%d", method_type_annotations->length());
2767
2768 int byte_i = 0; // byte index into method_type_annotations
2769 if (!rewrite_cp_refs_in_type_annotations_typeArray(method_type_annotations,
2770 byte_i, "method_info")) {
2771 log_debug(redefine, class, annotation)("bad method_type_annotations at %d", i);
2772 // propagate failure back to caller
2773 return false;
2774 }
2775 }
2776
2777 return true;
2778 } // end rewrite_cp_refs_in_methods_type_annotations()
2779
2780
2781 // Rewrite constant pool references in a type_annotations
2782 // field. This "structure" is adapted from the
2783 // RuntimeVisibleTypeAnnotations_attribute described in
2784 // section 4.7.20 of the Java SE 8 Edition of the VM spec:
2785 //
2786 // type_annotations_typeArray {
2787 // u2 num_annotations;
2788 // type_annotation annotations[num_annotations];
2789 // }
2790 //
2791 bool VM_RedefineClasses::rewrite_cp_refs_in_type_annotations_typeArray(
2792 AnnotationArray* type_annotations_typeArray, int &byte_i_ref,
2793 const char * location_mesg) {
2794
2795 if ((byte_i_ref + 2) > type_annotations_typeArray->length()) {
2796 // not enough room for num_annotations field
2797 log_debug(redefine, class, annotation)("length() is too small for num_annotations field");
2798 return false;
2799 }
2800
2801 u2 num_annotations = Bytes::get_Java_u2((address)
2802 type_annotations_typeArray->adr_at(byte_i_ref));
2803 byte_i_ref += 2;
2804
2805 log_debug(redefine, class, annotation)("num_type_annotations=%d", num_annotations);
2806
2807 int calc_num_annotations = 0;
2808 for (; calc_num_annotations < num_annotations; calc_num_annotations++) {
2809 if (!rewrite_cp_refs_in_type_annotation_struct(type_annotations_typeArray,
2810 byte_i_ref, location_mesg)) {
2811 log_debug(redefine, class, annotation)("bad type_annotation_struct at %d", calc_num_annotations);
2812 // propagate failure back to caller
2813 return false;
2814 }
2815 }
2816 assert(num_annotations == calc_num_annotations, "sanity check");
2817
2818 if (byte_i_ref != type_annotations_typeArray->length()) {
2819 log_debug(redefine, class, annotation)
2820 ("read wrong amount of bytes at end of processing type_annotations_typeArray (%d of %d bytes were read)",
2821 byte_i_ref, type_annotations_typeArray->length());
2822 return false;
2823 }
2824
2825 return true;
2826 } // end rewrite_cp_refs_in_type_annotations_typeArray()
2827
2828
2829 // Rewrite constant pool references in a type_annotation
2830 // field. This "structure" is adapted from the
2831 // RuntimeVisibleTypeAnnotations_attribute described in
2832 // section 4.7.20 of the Java SE 8 Edition of the VM spec:
2833 //
2834 // type_annotation {
2835 // u1 target_type;
2836 // union {
2837 // type_parameter_target;
2838 // supertype_target;
2839 // type_parameter_bound_target;
2840 // empty_target;
2841 // method_formal_parameter_target;
2842 // throws_target;
2843 // localvar_target;
2844 // catch_target;
2845 // offset_target;
2846 // type_argument_target;
2847 // } target_info;
2848 // type_path target_path;
2849 // annotation anno;
2850 // }
2851 //
2852 bool VM_RedefineClasses::rewrite_cp_refs_in_type_annotation_struct(
2853 AnnotationArray* type_annotations_typeArray, int &byte_i_ref,
2854 const char * location_mesg) {
2855
2856 if (!skip_type_annotation_target(type_annotations_typeArray,
2857 byte_i_ref, location_mesg)) {
2858 return false;
2859 }
2860
2861 if (!skip_type_annotation_type_path(type_annotations_typeArray, byte_i_ref)) {
2862 return false;
2863 }
2864
2865 if (!rewrite_cp_refs_in_annotation_struct(type_annotations_typeArray, byte_i_ref)) {
2866 return false;
2867 }
2868
2869 return true;
2870 } // end rewrite_cp_refs_in_type_annotation_struct()
2871
2872
2873 // Read, verify and skip over the target_type and target_info part
2874 // so that rewriting can continue in the later parts of the struct.
2875 //
2876 // u1 target_type;
2877 // union {
2878 // type_parameter_target;
2879 // supertype_target;
2880 // type_parameter_bound_target;
2881 // empty_target;
2882 // method_formal_parameter_target;
2883 // throws_target;
2884 // localvar_target;
2885 // catch_target;
2886 // offset_target;
2887 // type_argument_target;
2888 // } target_info;
2889 //
2890 bool VM_RedefineClasses::skip_type_annotation_target(
2891 AnnotationArray* type_annotations_typeArray, int &byte_i_ref,
2892 const char * location_mesg) {
2893
2894 if ((byte_i_ref + 1) > type_annotations_typeArray->length()) {
2895 // not enough room for a target_type let alone the rest of a type_annotation
2896 log_debug(redefine, class, annotation)("length() is too small for a target_type");
2897 return false;
2898 }
2899
2900 u1 target_type = type_annotations_typeArray->at(byte_i_ref);
2901 byte_i_ref += 1;
2902 log_debug(redefine, class, annotation)("target_type=0x%.2x", target_type);
2903 log_debug(redefine, class, annotation)("location=%s", location_mesg);
2904
2905 // Skip over target_info
2906 switch (target_type) {
2907 case 0x00:
2908 // kind: type parameter declaration of generic class or interface
2909 // location: ClassFile
2910 case 0x01:
2911 // kind: type parameter declaration of generic method or constructor
2912 // location: method_info
2913
2914 {
2915 // struct:
2916 // type_parameter_target {
2917 // u1 type_parameter_index;
2918 // }
2919 //
2920 if ((byte_i_ref + 1) > type_annotations_typeArray->length()) {
2921 log_debug(redefine, class, annotation)("length() is too small for a type_parameter_target");
2922 return false;
2923 }
2924
2925 u1 type_parameter_index = type_annotations_typeArray->at(byte_i_ref);
2926 byte_i_ref += 1;
2927
2928 log_debug(redefine, class, annotation)("type_parameter_target: type_parameter_index=%d", type_parameter_index);
2929 } break;
2930
2931 case 0x10:
2932 // kind: type in extends clause of class or interface declaration
2933 // or in implements clause of interface declaration
2934 // location: ClassFile
2935
2936 {
2937 // struct:
2938 // supertype_target {
2939 // u2 supertype_index;
2940 // }
2941 //
2942 if ((byte_i_ref + 2) > type_annotations_typeArray->length()) {
2943 log_debug(redefine, class, annotation)("length() is too small for a supertype_target");
2944 return false;
2945 }
2946
2947 u2 supertype_index = Bytes::get_Java_u2((address)
2948 type_annotations_typeArray->adr_at(byte_i_ref));
2949 byte_i_ref += 2;
2950
2951 log_debug(redefine, class, annotation)("supertype_target: supertype_index=%d", supertype_index);
2952 } break;
2953
2954 case 0x11:
2955 // kind: type in bound of type parameter declaration of generic class or interface
2956 // location: ClassFile
2957 case 0x12:
2958 // kind: type in bound of type parameter declaration of generic method or constructor
2959 // location: method_info
2960
2961 {
2962 // struct:
2963 // type_parameter_bound_target {
2964 // u1 type_parameter_index;
2965 // u1 bound_index;
2966 // }
2967 //
2968 if ((byte_i_ref + 2) > type_annotations_typeArray->length()) {
2969 log_debug(redefine, class, annotation)("length() is too small for a type_parameter_bound_target");
2970 return false;
2971 }
2972
2973 u1 type_parameter_index = type_annotations_typeArray->at(byte_i_ref);
2974 byte_i_ref += 1;
2975 u1 bound_index = type_annotations_typeArray->at(byte_i_ref);
2976 byte_i_ref += 1;
2977
2978 log_debug(redefine, class, annotation)
2979 ("type_parameter_bound_target: type_parameter_index=%d, bound_index=%d", type_parameter_index, bound_index);
2980 } break;
2981
2982 case 0x13:
2983 // kind: type in field declaration
2984 // location: field_info
2985 case 0x14:
2986 // kind: return type of method, or type of newly constructed object
2987 // location: method_info
2988 case 0x15:
2989 // kind: receiver type of method or constructor
2990 // location: method_info
2991
2992 {
2993 // struct:
2994 // empty_target {
2995 // }
2996 //
2997 log_debug(redefine, class, annotation)("empty_target");
2998 } break;
2999
3000 case 0x16:
3001 // kind: type in formal parameter declaration of method, constructor, or lambda expression
3002 // location: method_info
3003
3004 {
3005 // struct:
3006 // formal_parameter_target {
3007 // u1 formal_parameter_index;
3008 // }
3009 //
3010 if ((byte_i_ref + 1) > type_annotations_typeArray->length()) {
3011 log_debug(redefine, class, annotation)("length() is too small for a formal_parameter_target");
3012 return false;
3013 }
3014
3015 u1 formal_parameter_index = type_annotations_typeArray->at(byte_i_ref);
3016 byte_i_ref += 1;
3017
3018 log_debug(redefine, class, annotation)
3019 ("formal_parameter_target: formal_parameter_index=%d", formal_parameter_index);
3020 } break;
3021
3022 case 0x17:
3023 // kind: type in throws clause of method or constructor
3024 // location: method_info
3025
3026 {
3027 // struct:
3028 // throws_target {
3029 // u2 throws_type_index
3030 // }
3031 //
3032 if ((byte_i_ref + 2) > type_annotations_typeArray->length()) {
3033 log_debug(redefine, class, annotation)("length() is too small for a throws_target");
3034 return false;
3035 }
3036
3037 u2 throws_type_index = Bytes::get_Java_u2((address)
3038 type_annotations_typeArray->adr_at(byte_i_ref));
3039 byte_i_ref += 2;
3040
3041 log_debug(redefine, class, annotation)("throws_target: throws_type_index=%d", throws_type_index);
3042 } break;
3043
3044 case 0x40:
3045 // kind: type in local variable declaration
3046 // location: Code
3047 case 0x41:
3048 // kind: type in resource variable declaration
3049 // location: Code
3050
3051 {
3052 // struct:
3053 // localvar_target {
3054 // u2 table_length;
3055 // struct {
3056 // u2 start_pc;
3057 // u2 length;
3058 // u2 index;
3059 // } table[table_length];
3060 // }
3061 //
3062 if ((byte_i_ref + 2) > type_annotations_typeArray->length()) {
3063 // not enough room for a table_length let alone the rest of a localvar_target
3064 log_debug(redefine, class, annotation)("length() is too small for a localvar_target table_length");
3065 return false;
3066 }
3067
3068 u2 table_length = Bytes::get_Java_u2((address)
3069 type_annotations_typeArray->adr_at(byte_i_ref));
3070 byte_i_ref += 2;
3071
3072 log_debug(redefine, class, annotation)("localvar_target: table_length=%d", table_length);
3073
3074 int table_struct_size = 2 + 2 + 2; // 3 u2 variables per table entry
3075 int table_size = table_length * table_struct_size;
3076
3077 if ((byte_i_ref + table_size) > type_annotations_typeArray->length()) {
3078 // not enough room for a table
3079 log_debug(redefine, class, annotation)("length() is too small for a table array of length %d", table_length);
3080 return false;
3081 }
3082
3083 // Skip over table
3084 byte_i_ref += table_size;
3085 } break;
3086
3087 case 0x42:
3088 // kind: type in exception parameter declaration
3089 // location: Code
3090
3091 {
3092 // struct:
3093 // catch_target {
3094 // u2 exception_table_index;
3095 // }
3096 //
3097 if ((byte_i_ref + 2) > type_annotations_typeArray->length()) {
3098 log_debug(redefine, class, annotation)("length() is too small for a catch_target");
3099 return false;
3100 }
3101
3102 u2 exception_table_index = Bytes::get_Java_u2((address)
3103 type_annotations_typeArray->adr_at(byte_i_ref));
3104 byte_i_ref += 2;
3105
3106 log_debug(redefine, class, annotation)("catch_target: exception_table_index=%d", exception_table_index);
3107 } break;
3108
3109 case 0x43:
3110 // kind: type in instanceof expression
3111 // location: Code
3112 case 0x44:
3113 // kind: type in new expression
3114 // location: Code
3115 case 0x45:
3116 // kind: type in method reference expression using ::new
3117 // location: Code
3118 case 0x46:
3119 // kind: type in method reference expression using ::Identifier
3120 // location: Code
3121
3122 {
3123 // struct:
3124 // offset_target {
3125 // u2 offset;
3126 // }
3127 //
3128 if ((byte_i_ref + 2) > type_annotations_typeArray->length()) {
3129 log_debug(redefine, class, annotation)("length() is too small for a offset_target");
3130 return false;
3131 }
3132
3133 u2 offset = Bytes::get_Java_u2((address)
3134 type_annotations_typeArray->adr_at(byte_i_ref));
3135 byte_i_ref += 2;
3136
3137 log_debug(redefine, class, annotation)("offset_target: offset=%d", offset);
3138 } break;
3139
3140 case 0x47:
3141 // kind: type in cast expression
3142 // location: Code
3143 case 0x48:
3144 // kind: type argument for generic constructor in new expression or
3145 // explicit constructor invocation statement
3146 // location: Code
3147 case 0x49:
3148 // kind: type argument for generic method in method invocation expression
3149 // location: Code
3150 case 0x4A:
3151 // kind: type argument for generic constructor in method reference expression using ::new
3152 // location: Code
3153 case 0x4B:
3154 // kind: type argument for generic method in method reference expression using ::Identifier
3155 // location: Code
3156
3157 {
3158 // struct:
3159 // type_argument_target {
3160 // u2 offset;
3161 // u1 type_argument_index;
3162 // }
3163 //
3164 if ((byte_i_ref + 3) > type_annotations_typeArray->length()) {
3165 log_debug(redefine, class, annotation)("length() is too small for a type_argument_target");
3166 return false;
3167 }
3168
3169 u2 offset = Bytes::get_Java_u2((address)
3170 type_annotations_typeArray->adr_at(byte_i_ref));
3171 byte_i_ref += 2;
3172 u1 type_argument_index = type_annotations_typeArray->at(byte_i_ref);
3173 byte_i_ref += 1;
3174
3175 log_debug(redefine, class, annotation)
3176 ("type_argument_target: offset=%d, type_argument_index=%d", offset, type_argument_index);
3177 } break;
3178
3179 default:
3180 log_debug(redefine, class, annotation)("unknown target_type");
3181 #ifdef ASSERT
3182 ShouldNotReachHere();
3183 #endif
3184 return false;
3185 }
3186
3187 return true;
3188 } // end skip_type_annotation_target()
3189
3190
3191 // Read, verify and skip over the type_path part so that rewriting
3192 // can continue in the later parts of the struct.
3193 //
3194 // type_path {
3195 // u1 path_length;
3196 // {
3197 // u1 type_path_kind;
3198 // u1 type_argument_index;
3199 // } path[path_length];
3200 // }
3201 //
3202 bool VM_RedefineClasses::skip_type_annotation_type_path(
3203 AnnotationArray* type_annotations_typeArray, int &byte_i_ref) {
3204
3205 if ((byte_i_ref + 1) > type_annotations_typeArray->length()) {
3206 // not enough room for a path_length let alone the rest of the type_path
3207 log_debug(redefine, class, annotation)("length() is too small for a type_path");
3208 return false;
3209 }
3210
3211 u1 path_length = type_annotations_typeArray->at(byte_i_ref);
3212 byte_i_ref += 1;
3213
3214 log_debug(redefine, class, annotation)("type_path: path_length=%d", path_length);
3215
3216 int calc_path_length = 0;
3217 for (; calc_path_length < path_length; calc_path_length++) {
3218 if ((byte_i_ref + 1 + 1) > type_annotations_typeArray->length()) {
3219 // not enough room for a path
3220 log_debug(redefine, class, annotation)
3221 ("length() is too small for path entry %d of %d", calc_path_length, path_length);
3222 return false;
3223 }
3224
3225 u1 type_path_kind = type_annotations_typeArray->at(byte_i_ref);
3226 byte_i_ref += 1;
3227 u1 type_argument_index = type_annotations_typeArray->at(byte_i_ref);
3228 byte_i_ref += 1;
3229
3230 log_debug(redefine, class, annotation)
3231 ("type_path: path[%d]: type_path_kind=%d, type_argument_index=%d",
3232 calc_path_length, type_path_kind, type_argument_index);
3233
3234 if (type_path_kind > 3 || (type_path_kind != 3 && type_argument_index != 0)) {
3235 // not enough room for a path
3236 log_debug(redefine, class, annotation)("inconsistent type_path values");
3237 return false;
3238 }
3239 }
3240 assert(path_length == calc_path_length, "sanity check");
3241
3242 return true;
3243 } // end skip_type_annotation_type_path()
3244
3245
3246 // Rewrite constant pool references in the method's stackmap table.
3247 // These "structures" are adapted from the StackMapTable_attribute that
3248 // is described in section 4.8.4 of the 6.0 version of the VM spec
3249 // (dated 2005.10.26):
3250 // file:///net/quincunx.sfbay/export/gbracha/ClassFile-Java6.pdf
3251 //
3252 // stack_map {
3253 // u2 number_of_entries;
3254 // stack_map_frame entries[number_of_entries];
3255 // }
3256 //
3257 void VM_RedefineClasses::rewrite_cp_refs_in_stack_map_table(
3258 const methodHandle& method) {
3259
3260 if (!method->has_stackmap_table()) {
3261 return;
3262 }
3263
3264 AnnotationArray* stackmap_data = method->stackmap_data();
3265 address stackmap_p = (address)stackmap_data->adr_at(0);
3266 address stackmap_end = stackmap_p + stackmap_data->length();
3267
3268 assert(stackmap_p + 2 <= stackmap_end, "no room for number_of_entries");
3269 u2 number_of_entries = Bytes::get_Java_u2(stackmap_p);
3270 stackmap_p += 2;
3271
3272 log_debug(redefine, class, stackmap)("number_of_entries=%u", number_of_entries);
3273
3274 // walk through each stack_map_frame
3275 u2 calc_number_of_entries = 0;
3276 for (; calc_number_of_entries < number_of_entries; calc_number_of_entries++) {
3277 // The stack_map_frame structure is a u1 frame_type followed by
3278 // 0 or more bytes of data:
3279 //
3280 // union stack_map_frame {
3281 // same_frame;
3282 // same_locals_1_stack_item_frame;
3283 // same_locals_1_stack_item_frame_extended;
3284 // chop_frame;
3285 // same_frame_extended;
3286 // append_frame;
3287 // full_frame;
3288 // }
3289
3290 assert(stackmap_p + 1 <= stackmap_end, "no room for frame_type");
3291 u1 frame_type = *stackmap_p;
3292 stackmap_p++;
3293
3294 // same_frame {
3295 // u1 frame_type = SAME; /* 0-63 */
3296 // }
3297 if (frame_type <= 63) {
3298 // nothing more to do for same_frame
3299 }
3300
3301 // same_locals_1_stack_item_frame {
3302 // u1 frame_type = SAME_LOCALS_1_STACK_ITEM; /* 64-127 */
3303 // verification_type_info stack[1];
3304 // }
3305 else if (frame_type >= 64 && frame_type <= 127) {
3306 rewrite_cp_refs_in_verification_type_info(stackmap_p, stackmap_end,
3307 calc_number_of_entries, frame_type);
3308 }
3309
3310 // reserved for future use
3311 else if (frame_type >= 128 && frame_type <= 246) {
3312 // nothing more to do for reserved frame_types
3313 }
3314
3315 // same_locals_1_stack_item_frame_extended {
3316 // u1 frame_type = SAME_LOCALS_1_STACK_ITEM_EXTENDED; /* 247 */
3317 // u2 offset_delta;
3318 // verification_type_info stack[1];
3319 // }
3320 else if (frame_type == 247) {
3321 stackmap_p += 2;
3322 rewrite_cp_refs_in_verification_type_info(stackmap_p, stackmap_end,
3323 calc_number_of_entries, frame_type);
3324 }
3325
3326 // chop_frame {
3327 // u1 frame_type = CHOP; /* 248-250 */
3328 // u2 offset_delta;
3329 // }
3330 else if (frame_type >= 248 && frame_type <= 250) {
3331 stackmap_p += 2;
3332 }
3333
3334 // same_frame_extended {
3335 // u1 frame_type = SAME_FRAME_EXTENDED; /* 251*/
3336 // u2 offset_delta;
3337 // }
3338 else if (frame_type == 251) {
3339 stackmap_p += 2;
3340 }
3341
3342 // append_frame {
3343 // u1 frame_type = APPEND; /* 252-254 */
3344 // u2 offset_delta;
3345 // verification_type_info locals[frame_type - 251];
3346 // }
3347 else if (frame_type >= 252 && frame_type <= 254) {
3348 assert(stackmap_p + 2 <= stackmap_end,
3349 "no room for offset_delta");
3350 stackmap_p += 2;
3351 u1 len = frame_type - 251;
3352 for (u1 i = 0; i < len; i++) {
3353 rewrite_cp_refs_in_verification_type_info(stackmap_p, stackmap_end,
3354 calc_number_of_entries, frame_type);
3355 }
3356 }
3357
3358 // full_frame {
3359 // u1 frame_type = FULL_FRAME; /* 255 */
3360 // u2 offset_delta;
3361 // u2 number_of_locals;
3362 // verification_type_info locals[number_of_locals];
3363 // u2 number_of_stack_items;
3364 // verification_type_info stack[number_of_stack_items];
3365 // }
3366 else if (frame_type == 255) {
3367 assert(stackmap_p + 2 + 2 <= stackmap_end,
3368 "no room for smallest full_frame");
3369 stackmap_p += 2;
3370
3371 u2 number_of_locals = Bytes::get_Java_u2(stackmap_p);
3372 stackmap_p += 2;
3373
3374 for (u2 locals_i = 0; locals_i < number_of_locals; locals_i++) {
3375 rewrite_cp_refs_in_verification_type_info(stackmap_p, stackmap_end,
3376 calc_number_of_entries, frame_type);
3377 }
3378
3379 // Use the largest size for the number_of_stack_items, but only get
3380 // the right number of bytes.
3381 u2 number_of_stack_items = Bytes::get_Java_u2(stackmap_p);
3382 stackmap_p += 2;
3383
3384 for (u2 stack_i = 0; stack_i < number_of_stack_items; stack_i++) {
3385 rewrite_cp_refs_in_verification_type_info(stackmap_p, stackmap_end,
3386 calc_number_of_entries, frame_type);
3387 }
3388 }
3389 } // end while there is a stack_map_frame
3390 assert(number_of_entries == calc_number_of_entries, "sanity check");
3391 } // end rewrite_cp_refs_in_stack_map_table()
3392
3393
3394 // Rewrite constant pool references in the verification type info
3395 // portion of the method's stackmap table. These "structures" are
3396 // adapted from the StackMapTable_attribute that is described in
3397 // section 4.8.4 of the 6.0 version of the VM spec (dated 2005.10.26):
3398 // file:///net/quincunx.sfbay/export/gbracha/ClassFile-Java6.pdf
3399 //
3400 // The verification_type_info structure is a u1 tag followed by 0 or
3401 // more bytes of data:
3402 //
3403 // union verification_type_info {
3404 // Top_variable_info;
3405 // Integer_variable_info;
3406 // Float_variable_info;
3407 // Long_variable_info;
3408 // Double_variable_info;
3409 // Null_variable_info;
3410 // UninitializedThis_variable_info;
3411 // Object_variable_info;
3412 // Uninitialized_variable_info;
3413 // }
3414 //
3415 void VM_RedefineClasses::rewrite_cp_refs_in_verification_type_info(
3416 address& stackmap_p_ref, address stackmap_end, u2 frame_i,
3417 u1 frame_type) {
3418
3419 assert(stackmap_p_ref + 1 <= stackmap_end, "no room for tag");
3420 u1 tag = *stackmap_p_ref;
3421 stackmap_p_ref++;
3422
3423 switch (tag) {
3424 // Top_variable_info {
3425 // u1 tag = ITEM_Top; /* 0 */
3426 // }
3427 // verificationType.hpp has zero as ITEM_Bogus instead of ITEM_Top
3428 case 0: // fall through
3429
3430 // Integer_variable_info {
3431 // u1 tag = ITEM_Integer; /* 1 */
3432 // }
3433 case ITEM_Integer: // fall through
3434
3435 // Float_variable_info {
3436 // u1 tag = ITEM_Float; /* 2 */
3437 // }
3438 case ITEM_Float: // fall through
3439
3440 // Double_variable_info {
3441 // u1 tag = ITEM_Double; /* 3 */
3442 // }
3443 case ITEM_Double: // fall through
3444
3445 // Long_variable_info {
3446 // u1 tag = ITEM_Long; /* 4 */
3447 // }
3448 case ITEM_Long: // fall through
3449
3450 // Null_variable_info {
3451 // u1 tag = ITEM_Null; /* 5 */
3452 // }
3453 case ITEM_Null: // fall through
3454
3455 // UninitializedThis_variable_info {
3456 // u1 tag = ITEM_UninitializedThis; /* 6 */
3457 // }
3458 case ITEM_UninitializedThis:
3459 // nothing more to do for the above tag types
3460 break;
3461
3462 // Object_variable_info {
3463 // u1 tag = ITEM_Object; /* 7 */
3464 // u2 cpool_index;
3465 // }
3466 case ITEM_Object:
3467 {
3468 assert(stackmap_p_ref + 2 <= stackmap_end, "no room for cpool_index");
3469 u2 cpool_index = Bytes::get_Java_u2(stackmap_p_ref);
3470 u2 new_cp_index = find_new_index(cpool_index);
3471 if (new_cp_index != 0) {
3472 log_debug(redefine, class, stackmap)("mapped old cpool_index=%d", cpool_index);
3473 Bytes::put_Java_u2(stackmap_p_ref, new_cp_index);
3474 cpool_index = new_cp_index;
3475 }
3476 stackmap_p_ref += 2;
3477
3478 log_debug(redefine, class, stackmap)
3479 ("frame_i=%u, frame_type=%u, cpool_index=%d", frame_i, frame_type, cpool_index);
3480 } break;
3481
3482 // Uninitialized_variable_info {
3483 // u1 tag = ITEM_Uninitialized; /* 8 */
3484 // u2 offset;
3485 // }
3486 case ITEM_Uninitialized:
3487 assert(stackmap_p_ref + 2 <= stackmap_end, "no room for offset");
3488 stackmap_p_ref += 2;
3489 break;
3490
3491 default:
3492 log_debug(redefine, class, stackmap)("frame_i=%u, frame_type=%u, bad tag=0x%x", frame_i, frame_type, tag);
3493 ShouldNotReachHere();
3494 break;
3495 } // end switch (tag)
3496 } // end rewrite_cp_refs_in_verification_type_info()
3497
3498
3499 // Change the constant pool associated with klass scratch_class to scratch_cp.
3500 // scratch_cp_length elements are copied from scratch_cp to a smaller constant pool
3501 // and the smaller constant pool is associated with scratch_class.
3502 void VM_RedefineClasses::set_new_constant_pool(
3503 ClassLoaderData* loader_data,
3504 InstanceKlass* scratch_class, constantPoolHandle scratch_cp,
3505 int scratch_cp_length, TRAPS) {
3506 assert(scratch_cp->length() >= scratch_cp_length, "sanity check");
3507
3508 // scratch_cp is a merged constant pool and has enough space for a
3509 // worst case merge situation. We want to associate the minimum
3510 // sized constant pool with the klass to save space.
3511 ConstantPool* cp = ConstantPool::allocate(loader_data, scratch_cp_length, CHECK);
3512 constantPoolHandle smaller_cp(THREAD, cp);
3513
3514 // preserve version() value in the smaller copy
3515 int version = scratch_cp->version();
3516 assert(version != 0, "sanity check");
3517 smaller_cp->set_version(version);
3518
3519 // attach klass to new constant pool
3520 // reference to the cp holder is needed for copy_operands()
3521 smaller_cp->set_pool_holder(scratch_class);
3522
3523 smaller_cp->copy_fields(scratch_cp());
3524
3525 scratch_cp->copy_cp_to(1, scratch_cp_length - 1, smaller_cp, 1, THREAD);
3526 if (HAS_PENDING_EXCEPTION) {
3527 // Exception is handled in the caller
3528 loader_data->add_to_deallocate_list(smaller_cp());
3529 return;
3530 }
3531 scratch_cp = smaller_cp;
3532
3533 // attach new constant pool to klass
3534 scratch_class->set_constants(scratch_cp());
3535 scratch_cp->initialize_unresolved_klasses(loader_data, CHECK);
3536
3537 int i; // for portability
3538
3539 // update each field in klass to use new constant pool indices as needed
3540 int java_fields;
3541 int injected_fields;
3542 bool update_required = false;
3543 GrowableArray<FieldInfo>* fields = FieldInfoStream::create_FieldInfoArray(scratch_class->fieldinfo_stream(), &java_fields, &injected_fields);
3544 for (int i = 0; i < java_fields; i++) {
3545 FieldInfo* fi = fields->adr_at(i);
3546 jshort cur_index = fi->name_index();
3547 jshort new_index = find_new_index(cur_index);
3548 if (new_index != 0) {
3549 log_trace(redefine, class, constantpool)("field-name_index change: %d to %d", cur_index, new_index);
3550 fi->set_name_index(new_index);
3551 update_required = true;
3552 }
3553 cur_index = fi->signature_index();
3554 new_index = find_new_index(cur_index);
3555 if (new_index != 0) {
3556 log_trace(redefine, class, constantpool)("field-signature_index change: %d to %d", cur_index, new_index);
3557 fi->set_signature_index(new_index);
3558 update_required = true;
3559 }
3560 cur_index = fi->initializer_index();
3561 new_index = find_new_index(cur_index);
3562 if (new_index != 0) {
3563 log_trace(redefine, class, constantpool)("field-initval_index change: %d to %d", cur_index, new_index);
3564 fi->set_initializer_index(new_index);
3565 update_required = true;
3566 }
3567 cur_index = fi->generic_signature_index();
3568 new_index = find_new_index(cur_index);
3569 if (new_index != 0) {
3570 log_trace(redefine, class, constantpool)("field-generic_signature change: %d to %d", cur_index, new_index);
3571 fi->set_generic_signature_index(new_index);
3572 update_required = true;
3573 }
3574 }
3575 if (update_required) {
3576 Array<u1>* old_stream = scratch_class->fieldinfo_stream();
3577 assert(fields->length() == (java_fields + injected_fields), "Must be");
3578 Array<u1>* new_fis = FieldInfoStream::create_FieldInfoStream(fields, java_fields, injected_fields, scratch_class->class_loader_data(), CHECK);
3579 scratch_class->set_fieldinfo_stream(new_fis);
3580 MetadataFactory::free_array<u1>(scratch_class->class_loader_data(), old_stream);
3581 }
3582
3583 // Update constant pool indices in the inner classes info to use
3584 // new constant indices as needed. The inner classes info is a
3585 // quadruple:
3586 // (inner_class_info, outer_class_info, inner_name, inner_access_flags)
3587 InnerClassesIterator iter(scratch_class);
3588 for (; !iter.done(); iter.next()) {
3589 int cur_index = iter.inner_class_info_index();
3590 if (cur_index == 0) {
3591 continue; // JVM spec. allows null inner class refs so skip it
3592 }
3593 u2 new_index = find_new_index(cur_index);
3594 if (new_index != 0) {
3595 log_trace(redefine, class, constantpool)("inner_class_info change: %d to %d", cur_index, new_index);
3596 iter.set_inner_class_info_index(new_index);
3597 }
3598 cur_index = iter.outer_class_info_index();
3599 new_index = find_new_index(cur_index);
3600 if (new_index != 0) {
3601 log_trace(redefine, class, constantpool)("outer_class_info change: %d to %d", cur_index, new_index);
3602 iter.set_outer_class_info_index(new_index);
3603 }
3604 cur_index = iter.inner_name_index();
3605 new_index = find_new_index(cur_index);
3606 if (new_index != 0) {
3607 log_trace(redefine, class, constantpool)("inner_name change: %d to %d", cur_index, new_index);
3608 iter.set_inner_name_index(new_index);
3609 }
3610 } // end for each inner class
3611
3612 // Attach each method in klass to the new constant pool and update
3613 // to use new constant pool indices as needed:
3614 Array<Method*>* methods = scratch_class->methods();
3615 for (i = methods->length() - 1; i >= 0; i--) {
3616 methodHandle method(THREAD, methods->at(i));
3617 method->set_constants(scratch_cp());
3618
3619 u2 new_index = find_new_index(method->name_index());
3620 if (new_index != 0) {
3621 log_trace(redefine, class, constantpool)
3622 ("method-name_index change: %d to %d", method->name_index(), new_index);
3623 method->set_name_index(new_index);
3624 }
3625 new_index = find_new_index(method->signature_index());
3626 if (new_index != 0) {
3627 log_trace(redefine, class, constantpool)
3628 ("method-signature_index change: %d to %d", method->signature_index(), new_index);
3629 method->set_signature_index(new_index);
3630 }
3631 new_index = find_new_index(method->generic_signature_index());
3632 if (new_index != 0) {
3633 log_trace(redefine, class, constantpool)
3634 ("method-generic_signature_index change: %d to %d", method->generic_signature_index(), new_index);
3635 method->constMethod()->set_generic_signature_index(new_index);
3636 }
3637
3638 // Update constant pool indices in the method's checked exception
3639 // table to use new constant indices as needed.
3640 int cext_length = method->checked_exceptions_length();
3641 if (cext_length > 0) {
3642 CheckedExceptionElement * cext_table =
3643 method->checked_exceptions_start();
3644 for (int j = 0; j < cext_length; j++) {
3645 int cur_index = cext_table[j].class_cp_index;
3646 int new_index = find_new_index(cur_index);
3647 if (new_index != 0) {
3648 log_trace(redefine, class, constantpool)("cext-class_cp_index change: %d to %d", cur_index, new_index);
3649 cext_table[j].class_cp_index = (u2)new_index;
3650 }
3651 } // end for each checked exception table entry
3652 } // end if there are checked exception table entries
3653
3654 // Update each catch type index in the method's exception table
3655 // to use new constant pool indices as needed. The exception table
3656 // holds quadruple entries of the form:
3657 // (beg_bci, end_bci, handler_bci, klass_index)
3658
3659 ExceptionTable ex_table(method());
3660 int ext_length = ex_table.length();
3661
3662 for (int j = 0; j < ext_length; j ++) {
3663 int cur_index = ex_table.catch_type_index(j);
3664 u2 new_index = find_new_index(cur_index);
3665 if (new_index != 0) {
3666 log_trace(redefine, class, constantpool)("ext-klass_index change: %d to %d", cur_index, new_index);
3667 ex_table.set_catch_type_index(j, new_index);
3668 }
3669 } // end for each exception table entry
3670
3671 // Update constant pool indices in the method's local variable
3672 // table to use new constant indices as needed. The local variable
3673 // table hold sextuple entries of the form:
3674 // (start_pc, length, name_index, descriptor_index, signature_index, slot)
3675 int lvt_length = method->localvariable_table_length();
3676 if (lvt_length > 0) {
3677 LocalVariableTableElement * lv_table =
3678 method->localvariable_table_start();
3679 for (int j = 0; j < lvt_length; j++) {
3680 int cur_index = lv_table[j].name_cp_index;
3681 int new_index = find_new_index(cur_index);
3682 if (new_index != 0) {
3683 log_trace(redefine, class, constantpool)("lvt-name_cp_index change: %d to %d", cur_index, new_index);
3684 lv_table[j].name_cp_index = (u2)new_index;
3685 }
3686 cur_index = lv_table[j].descriptor_cp_index;
3687 new_index = find_new_index(cur_index);
3688 if (new_index != 0) {
3689 log_trace(redefine, class, constantpool)("lvt-descriptor_cp_index change: %d to %d", cur_index, new_index);
3690 lv_table[j].descriptor_cp_index = (u2)new_index;
3691 }
3692 cur_index = lv_table[j].signature_cp_index;
3693 new_index = find_new_index(cur_index);
3694 if (new_index != 0) {
3695 log_trace(redefine, class, constantpool)("lvt-signature_cp_index change: %d to %d", cur_index, new_index);
3696 lv_table[j].signature_cp_index = (u2)new_index;
3697 }
3698 } // end for each local variable table entry
3699 } // end if there are local variable table entries
3700
3701 // Update constant pool indices in the method's method_parameters.
3702 int mp_length = method->method_parameters_length();
3703 if (mp_length > 0) {
3704 MethodParametersElement* elem = method->method_parameters_start();
3705 for (int j = 0; j < mp_length; j++) {
3706 const int cp_index = elem[j].name_cp_index;
3707 const int new_cp_index = find_new_index(cp_index);
3708 if (new_cp_index != 0) {
3709 elem[j].name_cp_index = (u2)new_cp_index;
3710 }
3711 }
3712 }
3713
3714 rewrite_cp_refs_in_stack_map_table(method);
3715 } // end for each method
3716 } // end set_new_constant_pool()
3717
3718
3719 // Unevolving classes may point to methods of the_class directly
3720 // from their constant pool caches, itables, and/or vtables. We
3721 // use the ClassLoaderDataGraph::classes_do() facility and this helper
3722 // to fix up these pointers. MethodData also points to old methods and
3723 // must be cleaned.
3724
3725 // Adjust cpools and vtables closure
3726 void VM_RedefineClasses::AdjustAndCleanMetadata::do_klass(Klass* k) {
3727
3728 // This is a very busy routine. We don't want too much tracing
3729 // printed out.
3730 bool trace_name_printed = false;
3731
3732 // If the class being redefined is java.lang.Object, we need to fix all
3733 // array class vtables also. The _has_redefined_Object flag is global.
3734 // Once the java.lang.Object has been redefined (by the current or one
3735 // of the previous VM_RedefineClasses operations) we have to always
3736 // adjust method entries for array classes.
3737 if (k->is_array_klass() && _has_redefined_Object) {
3738 k->vtable().adjust_method_entries(&trace_name_printed);
3739
3740 } else if (k->is_instance_klass()) {
3741 HandleMark hm(_thread);
3742 InstanceKlass *ik = InstanceKlass::cast(k);
3743
3744 // Clean MethodData of this class's methods so they don't refer to
3745 // old methods that are no longer running.
3746 Array<Method*>* methods = ik->methods();
3747 int num_methods = methods->length();
3748 for (int index = 0; index < num_methods; ++index) {
3749 if (methods->at(index)->method_data() != nullptr) {
3750 methods->at(index)->method_data()->clean_weak_method_links();
3751 }
3752 }
3753
3754 // Adjust all vtables, default methods and itables, to clean out old methods.
3755 ResourceMark rm(_thread);
3756 if (ik->vtable_length() > 0) {
3757 ik->vtable().adjust_method_entries(&trace_name_printed);
3758 ik->adjust_default_methods(&trace_name_printed);
3759 }
3760
3761 if (ik->itable_length() > 0) {
3762 ik->itable().adjust_method_entries(&trace_name_printed);
3763 }
3764
3765 // The constant pools in other classes (other_cp) can refer to
3766 // old methods. We have to update method information in
3767 // other_cp's cache. If other_cp has a previous version, then we
3768 // have to repeat the process for each previous version. The
3769 // constant pool cache holds the Method*s for non-virtual
3770 // methods and for virtual, final methods.
3771 //
3772 // Special case: if the current class is being redefined by the current
3773 // VM_RedefineClasses operation, then new_cp has already been attached
3774 // to the_class and old_cp has already been added as a previous version.
3775 // The new_cp doesn't have any cached references to old methods so it
3776 // doesn't need to be updated and we could optimize by skipping it.
3777 // However, the current class can be marked as being redefined by another
3778 // VM_RedefineClasses operation which has already executed its doit_prologue
3779 // and needs cpcache method entries adjusted. For simplicity, the cpcache
3780 // update is done unconditionally. It should result in doing nothing for
3781 // classes being redefined by the current VM_RedefineClasses operation.
3782 // Method entries in the previous version(s) are adjusted as well.
3783 ConstantPoolCache* cp_cache;
3784
3785 // this klass' constant pool cache may need adjustment
3786 ConstantPool* other_cp = ik->constants();
3787 cp_cache = other_cp->cache();
3788 if (cp_cache != nullptr) {
3789 cp_cache->adjust_method_entries(&trace_name_printed);
3790 }
3791
3792 // the previous versions' constant pool caches may need adjustment
3793 for (InstanceKlass* pv_node = ik->previous_versions();
3794 pv_node != nullptr;
3795 pv_node = pv_node->previous_versions()) {
3796 cp_cache = pv_node->constants()->cache();
3797 if (cp_cache != nullptr) {
3798 cp_cache->adjust_method_entries(&trace_name_printed);
3799 }
3800 }
3801 }
3802 }
3803
3804 void VM_RedefineClasses::update_jmethod_ids() {
3805 for (int j = 0; j < _matching_methods_length; ++j) {
3806 Method* old_method = _matching_old_methods[j];
3807 jmethodID jmid = old_method->find_jmethod_id_or_null();
3808 if (jmid != nullptr) {
3809 // There is a jmethodID, change it to point to the new method
3810 Method* new_method = _matching_new_methods[j];
3811 Method::change_method_associated_with_jmethod_id(jmid, new_method);
3812 assert(Method::resolve_jmethod_id(jmid) == _matching_new_methods[j],
3813 "should be replaced");
3814 }
3815 }
3816 }
3817
3818 int VM_RedefineClasses::check_methods_and_mark_as_obsolete() {
3819 int emcp_method_count = 0;
3820 int obsolete_count = 0;
3821 int old_index = 0;
3822 for (int j = 0; j < _matching_methods_length; ++j, ++old_index) {
3823 Method* old_method = _matching_old_methods[j];
3824 Method* new_method = _matching_new_methods[j];
3825 Method* old_array_method;
3826
3827 // Maintain an old_index into the _old_methods array by skipping
3828 // deleted methods
3829 while ((old_array_method = _old_methods->at(old_index)) != old_method) {
3830 ++old_index;
3831 }
3832
3833 if (MethodComparator::methods_EMCP(old_method, new_method)) {
3834 // The EMCP definition from JSR-163 requires the bytecodes to be
3835 // the same with the exception of constant pool indices which may
3836 // differ. However, the constants referred to by those indices
3837 // must be the same.
3838 //
3839 // We use methods_EMCP() for comparison since constant pool
3840 // merging can remove duplicate constant pool entries that were
3841 // present in the old method and removed from the rewritten new
3842 // method. A faster binary comparison function would consider the
3843 // old and new methods to be different when they are actually
3844 // EMCP.
3845 //
3846 // The old and new methods are EMCP and you would think that we
3847 // could get rid of one of them here and now and save some space.
3848 // However, the concept of EMCP only considers the bytecodes and
3849 // the constant pool entries in the comparison. Other things,
3850 // e.g., the line number table (LNT) or the local variable table
3851 // (LVT) don't count in the comparison. So the new (and EMCP)
3852 // method can have a new LNT that we need so we can't just
3853 // overwrite the new method with the old method.
3854 //
3855 // When this routine is called, we have already attached the new
3856 // methods to the_class so the old methods are effectively
3857 // overwritten. However, if an old method is still executing,
3858 // then the old method cannot be collected until sometime after
3859 // the old method call has returned. So the overwriting of old
3860 // methods by new methods will save us space except for those
3861 // (hopefully few) old methods that are still executing.
3862 //
3863 // A method refers to a ConstMethod* and this presents another
3864 // possible avenue to space savings. The ConstMethod* in the
3865 // new method contains possibly new attributes (LNT, LVT, etc).
3866 // At first glance, it seems possible to save space by replacing
3867 // the ConstMethod* in the old method with the ConstMethod*
3868 // from the new method. The old and new methods would share the
3869 // same ConstMethod* and we would save the space occupied by
3870 // the old ConstMethod*. However, the ConstMethod* contains
3871 // a back reference to the containing method. Sharing the
3872 // ConstMethod* between two methods could lead to confusion in
3873 // the code that uses the back reference. This would lead to
3874 // brittle code that could be broken in non-obvious ways now or
3875 // in the future.
3876 //
3877 // Another possibility is to copy the ConstMethod* from the new
3878 // method to the old method and then overwrite the new method with
3879 // the old method. Since the ConstMethod* contains the bytecodes
3880 // for the method embedded in the oop, this option would change
3881 // the bytecodes out from under any threads executing the old
3882 // method and make the thread's bcp invalid. Since EMCP requires
3883 // that the bytecodes be the same modulo constant pool indices, it
3884 // is straight forward to compute the correct new bcp in the new
3885 // ConstMethod* from the old bcp in the old ConstMethod*. The
3886 // time consuming part would be searching all the frames in all
3887 // of the threads to find all of the calls to the old method.
3888 //
3889 // It looks like we will have to live with the limited savings
3890 // that we get from effectively overwriting the old methods
3891 // when the new methods are attached to the_class.
3892
3893 // Count number of methods that are EMCP. The method will be marked
3894 // old but not obsolete if it is EMCP.
3895 emcp_method_count++;
3896
3897 // An EMCP method is _not_ obsolete. An obsolete method has a
3898 // different jmethodID than the current method. An EMCP method
3899 // has the same jmethodID as the current method. Having the
3900 // same jmethodID for all EMCP versions of a method allows for
3901 // a consistent view of the EMCP methods regardless of which
3902 // EMCP method you happen to have in hand. For example, a
3903 // breakpoint set in one EMCP method will work for all EMCP
3904 // versions of the method including the current one.
3905 } else {
3906 // mark obsolete methods as such
3907 old_method->set_is_obsolete();
3908 obsolete_count++;
3909
3910 // obsolete methods need a unique idnum so they become new entries in
3911 // the jmethodID cache in InstanceKlass
3912 assert(old_method->method_idnum() == new_method->method_idnum(), "must match");
3913 u2 num = InstanceKlass::cast(_the_class)->next_method_idnum();
3914 if (num != ConstMethod::UNSET_IDNUM) {
3915 old_method->set_method_idnum(num);
3916 }
3917
3918 // With tracing we try not to "yack" too much. The position of
3919 // this trace assumes there are fewer obsolete methods than
3920 // EMCP methods.
3921 if (log_is_enabled(Trace, redefine, class, obsolete, mark)) {
3922 ResourceMark rm;
3923 log_trace(redefine, class, obsolete, mark)
3924 ("mark %s(%s) as obsolete", old_method->name()->as_C_string(), old_method->signature()->as_C_string());
3925 }
3926 }
3927 old_method->set_is_old();
3928 }
3929 for (int i = 0; i < _deleted_methods_length; ++i) {
3930 Method* old_method = _deleted_methods[i];
3931
3932 assert(!old_method->has_vtable_index(),
3933 "cannot delete methods with vtable entries");;
3934
3935 // Mark all deleted methods as old, obsolete and deleted
3936 old_method->set_is_deleted();
3937 old_method->set_is_old();
3938 old_method->set_is_obsolete();
3939 ++obsolete_count;
3940 // With tracing we try not to "yack" too much. The position of
3941 // this trace assumes there are fewer obsolete methods than
3942 // EMCP methods.
3943 if (log_is_enabled(Trace, redefine, class, obsolete, mark)) {
3944 ResourceMark rm;
3945 log_trace(redefine, class, obsolete, mark)
3946 ("mark deleted %s(%s) as obsolete", old_method->name()->as_C_string(), old_method->signature()->as_C_string());
3947 }
3948 }
3949 assert((emcp_method_count + obsolete_count) == _old_methods->length(),
3950 "sanity check");
3951 log_trace(redefine, class, obsolete, mark)("EMCP_cnt=%d, obsolete_cnt=%d", emcp_method_count, obsolete_count);
3952 return emcp_method_count;
3953 }
3954
3955 // This internal class transfers the native function registration from old methods
3956 // to new methods. It is designed to handle both the simple case of unchanged
3957 // native methods and the complex cases of native method prefixes being added and/or
3958 // removed.
3959 // It expects only to be used during the VM_RedefineClasses op (a safepoint).
3960 //
3961 // This class is used after the new methods have been installed in "the_class".
3962 //
3963 // So, for example, the following must be handled. Where 'm' is a method and
3964 // a number followed by an underscore is a prefix.
3965 //
3966 // Old Name New Name
3967 // Simple transfer to new method m -> m
3968 // Add prefix m -> 1_m
3969 // Remove prefix 1_m -> m
3970 // Simultaneous add of prefixes m -> 3_2_1_m
3971 // Simultaneous removal of prefixes 3_2_1_m -> m
3972 // Simultaneous add and remove 1_m -> 2_m
3973 // Same, caused by prefix removal only 3_2_1_m -> 3_2_m
3974 //
3975 class TransferNativeFunctionRegistration {
3976 private:
3977 InstanceKlass* the_class;
3978 int prefix_count;
3979 char** prefixes;
3980
3981 // Recursively search the binary tree of possibly prefixed method names.
3982 // Iteration could be used if all agents were well behaved. Full tree walk is
3983 // more resilent to agents not cleaning up intermediate methods.
3984 // Branch at each depth in the binary tree is:
3985 // (1) without the prefix.
3986 // (2) with the prefix.
3987 // where 'prefix' is the prefix at that 'depth' (first prefix, second prefix,...)
3988 Method* search_prefix_name_space(int depth, char* name_str, size_t name_len,
3989 Symbol* signature) {
3990 TempNewSymbol name_symbol = SymbolTable::probe(name_str, (int)name_len);
3991 if (name_symbol != nullptr) {
3992 Method* method = the_class->lookup_method(name_symbol, signature);
3993 if (method != nullptr) {
3994 // Even if prefixed, intermediate methods must exist.
3995 if (method->is_native()) {
3996 // Wahoo, we found a (possibly prefixed) version of the method, return it.
3997 return method;
3998 }
3999 if (depth < prefix_count) {
4000 // Try applying further prefixes (other than this one).
4001 method = search_prefix_name_space(depth+1, name_str, name_len, signature);
4002 if (method != nullptr) {
4003 return method; // found
4004 }
4005
4006 // Try adding this prefix to the method name and see if it matches
4007 // another method name.
4008 char* prefix = prefixes[depth];
4009 size_t prefix_len = strlen(prefix);
4010 size_t trial_len = name_len + prefix_len;
4011 char* trial_name_str = NEW_RESOURCE_ARRAY(char, trial_len + 1);
4012 strcpy(trial_name_str, prefix);
4013 strcat(trial_name_str, name_str);
4014 method = search_prefix_name_space(depth+1, trial_name_str, trial_len,
4015 signature);
4016 if (method != nullptr) {
4017 // If found along this branch, it was prefixed, mark as such
4018 method->set_is_prefixed_native();
4019 return method; // found
4020 }
4021 }
4022 }
4023 }
4024 return nullptr; // This whole branch bore nothing
4025 }
4026
4027 // Return the method name with old prefixes stripped away.
4028 char* method_name_without_prefixes(Method* method) {
4029 Symbol* name = method->name();
4030 char* name_str = name->as_utf8();
4031
4032 // Old prefixing may be defunct, strip prefixes, if any.
4033 for (int i = prefix_count-1; i >= 0; i--) {
4034 char* prefix = prefixes[i];
4035 size_t prefix_len = strlen(prefix);
4036 if (strncmp(prefix, name_str, prefix_len) == 0) {
4037 name_str += prefix_len;
4038 }
4039 }
4040 return name_str;
4041 }
4042
4043 // Strip any prefixes off the old native method, then try to find a
4044 // (possibly prefixed) new native that matches it.
4045 Method* strip_and_search_for_new_native(Method* method) {
4046 ResourceMark rm;
4047 char* name_str = method_name_without_prefixes(method);
4048 return search_prefix_name_space(0, name_str, strlen(name_str),
4049 method->signature());
4050 }
4051
4052 public:
4053
4054 // Construct a native method transfer processor for this class.
4055 TransferNativeFunctionRegistration(InstanceKlass* _the_class) {
4056 assert(SafepointSynchronize::is_at_safepoint(), "sanity check");
4057
4058 the_class = _the_class;
4059 prefixes = JvmtiExport::get_all_native_method_prefixes(&prefix_count);
4060 }
4061
4062 // Attempt to transfer any of the old or deleted methods that are native
4063 void transfer_registrations(Method** old_methods, int methods_length) {
4064 for (int j = 0; j < methods_length; j++) {
4065 Method* old_method = old_methods[j];
4066
4067 if (old_method->is_native() && old_method->has_native_function()) {
4068 Method* new_method = strip_and_search_for_new_native(old_method);
4069 if (new_method != nullptr) {
4070 // Actually set the native function in the new method.
4071 // Redefine does not send events (except CFLH), certainly not this
4072 // behind the scenes re-registration.
4073 new_method->set_native_function(old_method->native_function(),
4074 !Method::native_bind_event_is_interesting);
4075 }
4076 }
4077 }
4078 }
4079 };
4080
4081 // Don't lose the association between a native method and its JNI function.
4082 void VM_RedefineClasses::transfer_old_native_function_registrations(InstanceKlass* the_class) {
4083 TransferNativeFunctionRegistration transfer(the_class);
4084 transfer.transfer_registrations(_deleted_methods, _deleted_methods_length);
4085 transfer.transfer_registrations(_matching_old_methods, _matching_methods_length);
4086 }
4087
4088 // Deoptimize all compiled code that depends on the classes redefined.
4089 //
4090 // If the can_redefine_classes capability is obtained in the onload
4091 // phase or 'AlwaysRecordEvolDependencies' is true, then the compiler has
4092 // recorded all dependencies from startup. In that case we need only
4093 // deoptimize and throw away all compiled code that depends on the class.
4094 //
4095 // If can_redefine_classes is obtained sometime after the onload phase
4096 // (and 'AlwaysRecordEvolDependencies' is false) then the dependency
4097 // information may be incomplete. In that case the first call to
4098 // RedefineClasses causes all compiled code to be thrown away. As
4099 // can_redefine_classes has been obtained then all future compilations will
4100 // record dependencies so second and subsequent calls to RedefineClasses
4101 // need only throw away code that depends on the class.
4102 //
4103
4104 void VM_RedefineClasses::flush_dependent_code() {
4105 assert(SafepointSynchronize::is_at_safepoint(), "sanity check");
4106 assert(JvmtiExport::all_dependencies_are_recorded() || !AlwaysRecordEvolDependencies, "sanity check");
4107
4108 DeoptimizationScope deopt_scope;
4109
4110 // This is the first redefinition, mark all the nmethods for deoptimization
4111 if (!JvmtiExport::all_dependencies_are_recorded()) {
4112 CodeCache::mark_all_nmethods_for_evol_deoptimization(&deopt_scope);
4113 log_debug(redefine, class, nmethod)("Marked all nmethods for deopt");
4114 } else {
4115 CodeCache::mark_dependents_for_evol_deoptimization(&deopt_scope);
4116 log_debug(redefine, class, nmethod)("Marked dependent nmethods for deopt");
4117 }
4118
4119 deopt_scope.deoptimize_marked();
4120
4121 // From now on we know that the dependency information is complete
4122 JvmtiExport::set_all_dependencies_are_recorded(true);
4123 }
4124
4125 void VM_RedefineClasses::compute_added_deleted_matching_methods() {
4126 Method* old_method;
4127 Method* new_method;
4128
4129 _matching_old_methods = NEW_RESOURCE_ARRAY(Method*, _old_methods->length());
4130 _matching_new_methods = NEW_RESOURCE_ARRAY(Method*, _old_methods->length());
4131 _added_methods = NEW_RESOURCE_ARRAY(Method*, _new_methods->length());
4132 _deleted_methods = NEW_RESOURCE_ARRAY(Method*, _old_methods->length());
4133
4134 _matching_methods_length = 0;
4135 _deleted_methods_length = 0;
4136 _added_methods_length = 0;
4137
4138 int nj = 0;
4139 int oj = 0;
4140 while (true) {
4141 if (oj >= _old_methods->length()) {
4142 if (nj >= _new_methods->length()) {
4143 break; // we've looked at everything, done
4144 }
4145 // New method at the end
4146 new_method = _new_methods->at(nj);
4147 _added_methods[_added_methods_length++] = new_method;
4148 ++nj;
4149 } else if (nj >= _new_methods->length()) {
4150 // Old method, at the end, is deleted
4151 old_method = _old_methods->at(oj);
4152 _deleted_methods[_deleted_methods_length++] = old_method;
4153 ++oj;
4154 } else {
4155 old_method = _old_methods->at(oj);
4156 new_method = _new_methods->at(nj);
4157 if (old_method->name() == new_method->name()) {
4158 if (old_method->signature() == new_method->signature()) {
4159 _matching_old_methods[_matching_methods_length ] = old_method;
4160 _matching_new_methods[_matching_methods_length++] = new_method;
4161 ++nj;
4162 ++oj;
4163 } else {
4164 // added overloaded have already been moved to the end,
4165 // so this is a deleted overloaded method
4166 _deleted_methods[_deleted_methods_length++] = old_method;
4167 ++oj;
4168 }
4169 } else { // names don't match
4170 if (old_method->name()->fast_compare(new_method->name()) > 0) {
4171 // new method
4172 _added_methods[_added_methods_length++] = new_method;
4173 ++nj;
4174 } else {
4175 // deleted method
4176 _deleted_methods[_deleted_methods_length++] = old_method;
4177 ++oj;
4178 }
4179 }
4180 }
4181 }
4182 assert(_matching_methods_length + _deleted_methods_length == _old_methods->length(), "sanity");
4183 assert(_matching_methods_length + _added_methods_length == _new_methods->length(), "sanity");
4184 }
4185
4186
4187 void VM_RedefineClasses::swap_annotations(InstanceKlass* the_class,
4188 InstanceKlass* scratch_class) {
4189 // Swap annotation fields values
4190 Annotations* old_annotations = the_class->annotations();
4191 the_class->set_annotations(scratch_class->annotations());
4192 scratch_class->set_annotations(old_annotations);
4193 }
4194
4195
4196 // Install the redefinition of a class:
4197 // - house keeping (flushing breakpoints and caches, deoptimizing
4198 // dependent compiled code)
4199 // - replacing parts in the_class with parts from scratch_class
4200 // - adding a weak reference to track the obsolete but interesting
4201 // parts of the_class
4202 // - adjusting constant pool caches and vtables in other classes
4203 // that refer to methods in the_class. These adjustments use the
4204 // ClassLoaderDataGraph::classes_do() facility which only allows
4205 // a helper method to be specified. The interesting parameters
4206 // that we would like to pass to the helper method are saved in
4207 // static global fields in the VM operation.
4208 void VM_RedefineClasses::redefine_single_class(Thread* current, jclass the_jclass,
4209 InstanceKlass* scratch_class) {
4210
4211 HandleMark hm(current); // make sure handles from this call are freed
4212
4213 if (log_is_enabled(Info, redefine, class, timer)) {
4214 _timer_rsc_phase1.start();
4215 }
4216
4217 InstanceKlass* the_class = get_ik(the_jclass);
4218
4219 // Set a flag to control and optimize adjusting method entries
4220 _has_redefined_Object |= the_class == vmClasses::Object_klass();
4221
4222 // Remove all breakpoints in methods of this class
4223 JvmtiBreakpoints& jvmti_breakpoints = JvmtiCurrentBreakpoints::get_jvmti_breakpoints();
4224 jvmti_breakpoints.clearall_in_class_at_safepoint(the_class);
4225
4226 _old_methods = the_class->methods();
4227 _new_methods = scratch_class->methods();
4228 _the_class = the_class;
4229 compute_added_deleted_matching_methods();
4230 update_jmethod_ids();
4231
4232 _any_class_has_resolved_methods = the_class->has_resolved_methods() || _any_class_has_resolved_methods;
4233
4234 // Attach new constant pool to the original klass. The original
4235 // klass still refers to the old constant pool (for now).
4236 scratch_class->constants()->set_pool_holder(the_class);
4237
4238 #if 0
4239 // In theory, with constant pool merging in place we should be able
4240 // to save space by using the new, merged constant pool in place of
4241 // the old constant pool(s). By "pool(s)" I mean the constant pool in
4242 // the klass version we are replacing now and any constant pool(s) in
4243 // previous versions of klass. Nice theory, doesn't work in practice.
4244 // When this code is enabled, even simple programs throw NullPointer
4245 // exceptions. I'm guessing that this is caused by some constant pool
4246 // cache difference between the new, merged constant pool and the
4247 // constant pool that was just being used by the klass. I'm keeping
4248 // this code around to archive the idea, but the code has to remain
4249 // disabled for now.
4250
4251 // Attach each old method to the new constant pool. This can be
4252 // done here since we are past the bytecode verification and
4253 // constant pool optimization phases.
4254 for (int i = _old_methods->length() - 1; i >= 0; i--) {
4255 Method* method = _old_methods->at(i);
4256 method->set_constants(scratch_class->constants());
4257 }
4258
4259 // NOTE: this doesn't work because you can redefine the same class in two
4260 // threads, each getting their own constant pool data appended to the
4261 // original constant pool. In order for the new methods to work when they
4262 // become old methods, they need to keep their updated copy of the constant pool.
4263
4264 {
4265 // walk all previous versions of the klass
4266 InstanceKlass *ik = the_class;
4267 PreviousVersionWalker pvw(ik);
4268 do {
4269 ik = pvw.next_previous_version();
4270 if (ik != nullptr) {
4271
4272 // attach previous version of klass to the new constant pool
4273 ik->set_constants(scratch_class->constants());
4274
4275 // Attach each method in the previous version of klass to the
4276 // new constant pool
4277 Array<Method*>* prev_methods = ik->methods();
4278 for (int i = prev_methods->length() - 1; i >= 0; i--) {
4279 Method* method = prev_methods->at(i);
4280 method->set_constants(scratch_class->constants());
4281 }
4282 }
4283 } while (ik != nullptr);
4284 }
4285 #endif
4286
4287 // Replace methods and constantpool
4288 the_class->set_methods(_new_methods);
4289 scratch_class->set_methods(_old_methods); // To prevent potential GCing of the old methods,
4290 // and to be able to undo operation easily.
4291
4292 Array<int>* old_ordering = the_class->method_ordering();
4293 the_class->set_method_ordering(scratch_class->method_ordering());
4294 scratch_class->set_method_ordering(old_ordering);
4295
4296 ConstantPool* old_constants = the_class->constants();
4297 the_class->set_constants(scratch_class->constants());
4298 scratch_class->set_constants(old_constants); // See the previous comment.
4299 #if 0
4300 // We are swapping the guts of "the new class" with the guts of "the
4301 // class". Since the old constant pool has just been attached to "the
4302 // new class", it seems logical to set the pool holder in the old
4303 // constant pool also. However, doing this will change the observable
4304 // class hierarchy for any old methods that are still executing. A
4305 // method can query the identity of its "holder" and this query uses
4306 // the method's constant pool link to find the holder. The change in
4307 // holding class from "the class" to "the new class" can confuse
4308 // things.
4309 //
4310 // Setting the old constant pool's holder will also cause
4311 // verification done during vtable initialization below to fail.
4312 // During vtable initialization, the vtable's class is verified to be
4313 // a subtype of the method's holder. The vtable's class is "the
4314 // class" and the method's holder is gotten from the constant pool
4315 // link in the method itself. For "the class"'s directly implemented
4316 // methods, the method holder is "the class" itself (as gotten from
4317 // the new constant pool). The check works fine in this case. The
4318 // check also works fine for methods inherited from super classes.
4319 //
4320 // Miranda methods are a little more complicated. A miranda method is
4321 // provided by an interface when the class implementing the interface
4322 // does not provide its own method. These interfaces are implemented
4323 // internally as an InstanceKlass. These special instanceKlasses
4324 // share the constant pool of the class that "implements" the
4325 // interface. By sharing the constant pool, the method holder of a
4326 // miranda method is the class that "implements" the interface. In a
4327 // non-redefine situation, the subtype check works fine. However, if
4328 // the old constant pool's pool holder is modified, then the check
4329 // fails because there is no class hierarchy relationship between the
4330 // vtable's class and "the new class".
4331
4332 old_constants->set_pool_holder(scratch_class());
4333 #endif
4334
4335 // track number of methods that are EMCP for add_previous_version() call below
4336 int emcp_method_count = check_methods_and_mark_as_obsolete();
4337 transfer_old_native_function_registrations(the_class);
4338
4339 if (scratch_class->get_cached_class_file() != the_class->get_cached_class_file()) {
4340 // 1. the_class doesn't have a cache yet, scratch_class does have a cache.
4341 // 2. The same class can be present twice in the scratch classes list or there
4342 // are multiple concurrent RetransformClasses calls on different threads.
4343 // the_class and scratch_class have the same cached bytes, but different buffers.
4344 // In such cases we need to deallocate one of the buffers.
4345 // 3. RedefineClasses and the_class has cached bytes from a previous transformation.
4346 // In the case we need to use class bytes from scratch_class.
4347 if (the_class->get_cached_class_file() != nullptr) {
4348 os::free(the_class->get_cached_class_file());
4349 }
4350 the_class->set_cached_class_file(scratch_class->get_cached_class_file());
4351 }
4352
4353 // null out in scratch class to not delete twice. The class to be redefined
4354 // always owns these bytes.
4355 scratch_class->set_cached_class_file(nullptr);
4356
4357 // Replace inner_classes
4358 Array<u2>* old_inner_classes = the_class->inner_classes();
4359 the_class->set_inner_classes(scratch_class->inner_classes());
4360 scratch_class->set_inner_classes(old_inner_classes);
4361
4362 // Initialize the vtable and interface table after
4363 // methods have been rewritten
4364 // no exception should happen here since we explicitly
4365 // do not check loader constraints.
4366 // compare_and_normalize_class_versions has already checked:
4367 // - classloaders unchanged, signatures unchanged
4368 // - all instanceKlasses for redefined classes reused & contents updated
4369 the_class->vtable().initialize_vtable();
4370 the_class->itable().initialize_itable();
4371
4372 // Update jmethodID cache if present.
4373 the_class->update_methods_jmethod_cache();
4374
4375 // Copy the "source debug extension" attribute from new class version
4376 the_class->set_source_debug_extension(
4377 scratch_class->source_debug_extension(),
4378 scratch_class->source_debug_extension() == nullptr ? 0 :
4379 (int)strlen(scratch_class->source_debug_extension()));
4380
4381 // Use of javac -g could be different in the old and the new
4382 if (scratch_class->has_localvariable_table() !=
4383 the_class->has_localvariable_table()) {
4384 the_class->set_has_localvariable_table(scratch_class->has_localvariable_table());
4385 }
4386
4387 swap_annotations(the_class, scratch_class);
4388
4389 // Replace minor version number of class file
4390 u2 old_minor_version = the_class->constants()->minor_version();
4391 the_class->constants()->set_minor_version(scratch_class->constants()->minor_version());
4392 scratch_class->constants()->set_minor_version(old_minor_version);
4393
4394 // Replace major version number of class file
4395 u2 old_major_version = the_class->constants()->major_version();
4396 the_class->constants()->set_major_version(scratch_class->constants()->major_version());
4397 scratch_class->constants()->set_major_version(old_major_version);
4398
4399 // Replace CP indexes for class and name+type of enclosing method
4400 u2 old_class_idx = the_class->enclosing_method_class_index();
4401 u2 old_method_idx = the_class->enclosing_method_method_index();
4402 the_class->set_enclosing_method_indices(
4403 scratch_class->enclosing_method_class_index(),
4404 scratch_class->enclosing_method_method_index());
4405 scratch_class->set_enclosing_method_indices(old_class_idx, old_method_idx);
4406
4407 if (!the_class->has_been_redefined()) {
4408 the_class->set_has_been_redefined();
4409 }
4410
4411 // Scratch class is unloaded but still needs cleaning, and skipping for CDS.
4412 scratch_class->set_is_scratch_class();
4413
4414 // keep track of previous versions of this class
4415 the_class->add_previous_version(scratch_class, emcp_method_count);
4416
4417 _timer_rsc_phase1.stop();
4418 if (log_is_enabled(Info, redefine, class, timer)) {
4419 _timer_rsc_phase2.start();
4420 }
4421
4422 if (the_class->oop_map_cache() != nullptr) {
4423 // Flush references to any obsolete methods from the oop map cache
4424 // so that obsolete methods are not pinned.
4425 the_class->oop_map_cache()->flush_obsolete_entries();
4426 }
4427
4428 increment_class_counter(the_class);
4429
4430 if (EventClassRedefinition::is_enabled()) {
4431 EventClassRedefinition event;
4432 event.set_classModificationCount(java_lang_Class::classRedefinedCount(the_class->java_mirror()));
4433 event.set_redefinedClass(the_class);
4434 event.set_redefinitionId(_id);
4435 event.commit();
4436 }
4437
4438 {
4439 ResourceMark rm(current);
4440 // increment the classRedefinedCount field in the_class and in any
4441 // direct and indirect subclasses of the_class
4442 log_info(redefine, class, load)
4443 ("redefined name=%s, count=%d (avail_mem=" UINT64_FORMAT "K)",
4444 the_class->external_name(), java_lang_Class::classRedefinedCount(the_class->java_mirror()), os::available_memory() >> 10);
4445 Events::log_redefinition(current, "redefined class name=%s, count=%d",
4446 the_class->external_name(),
4447 java_lang_Class::classRedefinedCount(the_class->java_mirror()));
4448
4449 }
4450 _timer_rsc_phase2.stop();
4451
4452 } // end redefine_single_class()
4453
4454
4455 // Increment the classRedefinedCount field in the specific InstanceKlass
4456 // and in all direct and indirect subclasses.
4457 void VM_RedefineClasses::increment_class_counter(InstanceKlass* ik) {
4458 for (ClassHierarchyIterator iter(ik); !iter.done(); iter.next()) {
4459 // Only update instanceKlasses
4460 Klass* sub = iter.klass();
4461 if (sub->is_instance_klass()) {
4462 oop class_mirror = InstanceKlass::cast(sub)->java_mirror();
4463 Klass* class_oop = java_lang_Class::as_Klass(class_mirror);
4464 int new_count = java_lang_Class::classRedefinedCount(class_mirror) + 1;
4465 java_lang_Class::set_classRedefinedCount(class_mirror, new_count);
4466
4467 if (class_oop != _the_class) {
4468 // _the_class count is printed at end of redefine_single_class()
4469 log_debug(redefine, class, subclass)("updated count in subclass=%s to %d", ik->external_name(), new_count);
4470 }
4471 }
4472 }
4473 }
4474
4475 void VM_RedefineClasses::CheckClass::do_klass(Klass* k) {
4476 bool no_old_methods = true; // be optimistic
4477
4478 // Both array and instance classes have vtables.
4479 // a vtable should never contain old or obsolete methods
4480 ResourceMark rm(_thread);
4481 if (k->vtable_length() > 0 &&
4482 !k->vtable().check_no_old_or_obsolete_entries()) {
4483 if (log_is_enabled(Trace, redefine, class, obsolete, metadata)) {
4484 log_trace(redefine, class, obsolete, metadata)
4485 ("klassVtable::check_no_old_or_obsolete_entries failure -- OLD or OBSOLETE method found -- class: %s",
4486 k->signature_name());
4487 k->vtable().dump_vtable();
4488 }
4489 no_old_methods = false;
4490 }
4491
4492 if (k->is_instance_klass()) {
4493 HandleMark hm(_thread);
4494 InstanceKlass *ik = InstanceKlass::cast(k);
4495
4496 // an itable should never contain old or obsolete methods
4497 if (ik->itable_length() > 0 &&
4498 !ik->itable().check_no_old_or_obsolete_entries()) {
4499 if (log_is_enabled(Trace, redefine, class, obsolete, metadata)) {
4500 log_trace(redefine, class, obsolete, metadata)
4501 ("klassItable::check_no_old_or_obsolete_entries failure -- OLD or OBSOLETE method found -- class: %s",
4502 ik->signature_name());
4503 ik->itable().dump_itable();
4504 }
4505 no_old_methods = false;
4506 }
4507
4508 // the constant pool cache should never contain non-deleted old or obsolete methods
4509 if (ik->constants() != nullptr &&
4510 ik->constants()->cache() != nullptr &&
4511 !ik->constants()->cache()->check_no_old_or_obsolete_entries()) {
4512 if (log_is_enabled(Trace, redefine, class, obsolete, metadata)) {
4513 log_trace(redefine, class, obsolete, metadata)
4514 ("cp-cache::check_no_old_or_obsolete_entries failure -- OLD or OBSOLETE method found -- class: %s",
4515 ik->signature_name());
4516 ik->constants()->cache()->dump_cache();
4517 }
4518 no_old_methods = false;
4519 }
4520 }
4521
4522 // print and fail guarantee if old methods are found.
4523 if (!no_old_methods) {
4524 if (log_is_enabled(Trace, redefine, class, obsolete, metadata)) {
4525 dump_methods();
4526 } else {
4527 log_trace(redefine, class)("Use the '-Xlog:redefine+class*:' option "
4528 "to see more info about the following guarantee() failure.");
4529 }
4530 guarantee(false, "OLD and/or OBSOLETE method(s) found");
4531 }
4532 }
4533
4534 u8 VM_RedefineClasses::next_id() {
4535 while (true) {
4536 u8 id = _id_counter;
4537 u8 next_id = id + 1;
4538 u8 result = Atomic::cmpxchg(&_id_counter, id, next_id);
4539 if (result == id) {
4540 return next_id;
4541 }
4542 }
4543 }
4544
4545 void VM_RedefineClasses::dump_methods() {
4546 int j;
4547 log_trace(redefine, class, dump)("_old_methods --");
4548 for (j = 0; j < _old_methods->length(); ++j) {
4549 LogStreamHandle(Trace, redefine, class, dump) log_stream;
4550 Method* m = _old_methods->at(j);
4551 log_stream.print("%4d (%5d) ", j, m->vtable_index());
4552 m->access_flags().print_on(&log_stream);
4553 log_stream.print(" -- ");
4554 m->print_name(&log_stream);
4555 log_stream.cr();
4556 }
4557 log_trace(redefine, class, dump)("_new_methods --");
4558 for (j = 0; j < _new_methods->length(); ++j) {
4559 LogStreamHandle(Trace, redefine, class, dump) log_stream;
4560 Method* m = _new_methods->at(j);
4561 log_stream.print("%4d (%5d) ", j, m->vtable_index());
4562 m->access_flags().print_on(&log_stream);
4563 log_stream.print(" -- ");
4564 m->print_name(&log_stream);
4565 log_stream.cr();
4566 }
4567 log_trace(redefine, class, dump)("_matching_methods --");
4568 for (j = 0; j < _matching_methods_length; ++j) {
4569 LogStreamHandle(Trace, redefine, class, dump) log_stream;
4570 Method* m = _matching_old_methods[j];
4571 log_stream.print("%4d (%5d) ", j, m->vtable_index());
4572 m->access_flags().print_on(&log_stream);
4573 log_stream.print(" -- ");
4574 m->print_name();
4575 log_stream.cr();
4576
4577 m = _matching_new_methods[j];
4578 log_stream.print(" (%5d) ", m->vtable_index());
4579 m->access_flags().print_on(&log_stream);
4580 log_stream.cr();
4581 }
4582 log_trace(redefine, class, dump)("_deleted_methods --");
4583 for (j = 0; j < _deleted_methods_length; ++j) {
4584 LogStreamHandle(Trace, redefine, class, dump) log_stream;
4585 Method* m = _deleted_methods[j];
4586 log_stream.print("%4d (%5d) ", j, m->vtable_index());
4587 m->access_flags().print_on(&log_stream);
4588 log_stream.print(" -- ");
4589 m->print_name(&log_stream);
4590 log_stream.cr();
4591 }
4592 log_trace(redefine, class, dump)("_added_methods --");
4593 for (j = 0; j < _added_methods_length; ++j) {
4594 LogStreamHandle(Trace, redefine, class, dump) log_stream;
4595 Method* m = _added_methods[j];
4596 log_stream.print("%4d (%5d) ", j, m->vtable_index());
4597 m->access_flags().print_on(&log_stream);
4598 log_stream.print(" -- ");
4599 m->print_name(&log_stream);
4600 log_stream.cr();
4601 }
4602 }
4603
4604 void VM_RedefineClasses::print_on_error(outputStream* st) const {
4605 VM_Operation::print_on_error(st);
4606 if (_the_class != nullptr) {
4607 ResourceMark rm;
4608 st->print_cr(", redefining class %s", _the_class->external_name());
4609 }
4610 }