1 /*
2 * Copyright (c) 2003, 2023, 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/metaspaceShared.hpp"
27 #include "classfile/classFileStream.hpp"
28 #include "classfile/classLoaderDataGraph.hpp"
29 #include "classfile/classLoadInfo.hpp"
30 #include "classfile/javaClasses.inline.hpp"
31 #include "classfile/metadataOnStackMark.hpp"
32 #include "classfile/symbolTable.hpp"
33 #include "classfile/klassFactory.hpp"
34 #include "classfile/verifier.hpp"
35 #include "classfile/vmClasses.hpp"
36 #include "classfile/vmSymbols.hpp"
37 #include "code/codeCache.hpp"
38 #include "compiler/compileBroker.hpp"
39 #include "interpreter/oopMapCache.hpp"
40 #include "interpreter/rewriter.hpp"
41 #include "jfr/jfrEvents.hpp"
42 #include "logging/logStream.hpp"
43 #include "memory/metadataFactory.hpp"
44 #include "memory/resourceArea.hpp"
45 #include "memory/universe.hpp"
46 #include "oops/annotations.hpp"
47 #include "oops/constantPool.hpp"
48 #include "oops/fieldStreams.inline.hpp"
49 #include "oops/klass.inline.hpp"
50 #include "oops/klassVtable.hpp"
51 #include "oops/oop.inline.hpp"
52 #include "oops/recordComponent.hpp"
53 #include "prims/jvmtiImpl.hpp"
54 #include "prims/jvmtiRedefineClasses.hpp"
55 #include "prims/jvmtiThreadState.inline.hpp"
56 #include "prims/resolvedMethodTable.hpp"
57 #include "prims/methodComparator.hpp"
58 #include "runtime/atomic.hpp"
59 #include "runtime/deoptimization.hpp"
60 #include "runtime/handles.inline.hpp"
61 #include "runtime/jniHandles.inline.hpp"
62 #include "runtime/relocator.hpp"
63 #include "runtime/safepointVerifiers.hpp"
64 #include "utilities/bitMap.inline.hpp"
65 #include "utilities/checkedCast.hpp"
66 #include "utilities/events.hpp"
67
68 Array<Method*>* VM_RedefineClasses::_old_methods = nullptr;
69 Array<Method*>* VM_RedefineClasses::_new_methods = nullptr;
70 Method** VM_RedefineClasses::_matching_old_methods = nullptr;
71 Method** VM_RedefineClasses::_matching_new_methods = nullptr;
72 Method** VM_RedefineClasses::_deleted_methods = nullptr;
73 Method** VM_RedefineClasses::_added_methods = nullptr;
74 int VM_RedefineClasses::_matching_methods_length = 0;
75 int VM_RedefineClasses::_deleted_methods_length = 0;
76 int VM_RedefineClasses::_added_methods_length = 0;
77
78 // This flag is global as the constructor does not reset it:
79 bool VM_RedefineClasses::_has_redefined_Object = false;
80 u8 VM_RedefineClasses::_id_counter = 0;
81
82 VM_RedefineClasses::VM_RedefineClasses(jint class_count,
83 const jvmtiClassDefinition *class_defs,
84 JvmtiClassLoadKind class_load_kind) {
85 _class_count = class_count;
86 _class_defs = class_defs;
87 _class_load_kind = class_load_kind;
88 _any_class_has_resolved_methods = false;
89 _res = JVMTI_ERROR_NONE;
90 _the_class = nullptr;
91 _id = next_id();
92 }
93
94 static inline InstanceKlass* get_ik(jclass def) {
95 oop mirror = JNIHandles::resolve_non_null(def);
96 return InstanceKlass::cast(java_lang_Class::as_Klass(mirror));
97 }
98
99 // If any of the classes are being redefined, wait
100 // Parallel constant pool merging leads to indeterminate constant pools.
101 void VM_RedefineClasses::lock_classes() {
102 JvmtiThreadState *state = JvmtiThreadState::state_for(JavaThread::current());
103 GrowableArray<Klass*>* redef_classes = state->get_classes_being_redefined();
104
105 MonitorLocker ml(RedefineClasses_lock);
106
107 if (redef_classes == nullptr) {
108 redef_classes = new (mtClass) GrowableArray<Klass*>(1, mtClass);
109 state->set_classes_being_redefined(redef_classes);
110 }
111
112 bool has_redefined;
113 do {
114 has_redefined = false;
115 // Go through classes each time until none are being redefined. Skip
116 // the ones that are being redefined by this thread currently. Class file
117 // load hook event may trigger new class redefine when we are redefining
118 // a class (after lock_classes()).
119 for (int i = 0; i < _class_count; i++) {
120 InstanceKlass* ik = get_ik(_class_defs[i].klass);
121 // Check if we are currently redefining the class in this thread already.
122 if (redef_classes->contains(ik)) {
123 assert(ik->is_being_redefined(), "sanity");
124 } else {
125 if (ik->is_being_redefined()) {
126 ml.wait();
127 has_redefined = true;
128 break; // for loop
129 }
130 }
131 }
132 } while (has_redefined);
133
134 for (int i = 0; i < _class_count; i++) {
135 InstanceKlass* ik = get_ik(_class_defs[i].klass);
136 redef_classes->push(ik); // Add to the _classes_being_redefined list
137 ik->set_is_being_redefined(true);
138 }
139 ml.notify_all();
140 }
141
142 void VM_RedefineClasses::unlock_classes() {
143 JvmtiThreadState *state = JvmtiThreadState::state_for(JavaThread::current());
144 GrowableArray<Klass*>* redef_classes = state->get_classes_being_redefined();
145 assert(redef_classes != nullptr, "_classes_being_redefined is not allocated");
146
147 MonitorLocker ml(RedefineClasses_lock);
148
149 for (int i = _class_count - 1; i >= 0; i--) {
150 InstanceKlass* def_ik = get_ik(_class_defs[i].klass);
151 if (redef_classes->length() > 0) {
152 // Remove the class from _classes_being_redefined list
153 Klass* k = redef_classes->pop();
154 assert(def_ik == k, "unlocking wrong class");
155 }
156 assert(def_ik->is_being_redefined(),
157 "should be being redefined to get here");
158
159 // Unlock after we finish all redefines for this class within
160 // the thread. Same class can be pushed to the list multiple
161 // times (not more than once by each recursive redefinition).
162 if (!redef_classes->contains(def_ik)) {
163 def_ik->set_is_being_redefined(false);
164 }
165 }
166 ml.notify_all();
167 }
168
169 bool VM_RedefineClasses::doit_prologue() {
170 if (_class_count == 0) {
171 _res = JVMTI_ERROR_NONE;
172 return false;
173 }
174 if (_class_defs == nullptr) {
175 _res = JVMTI_ERROR_NULL_POINTER;
176 return false;
177 }
178
179 for (int i = 0; i < _class_count; i++) {
180 if (_class_defs[i].klass == nullptr) {
181 _res = JVMTI_ERROR_INVALID_CLASS;
182 return false;
183 }
184 if (_class_defs[i].class_byte_count == 0) {
185 _res = JVMTI_ERROR_INVALID_CLASS_FORMAT;
186 return false;
187 }
188 if (_class_defs[i].class_bytes == nullptr) {
189 _res = JVMTI_ERROR_NULL_POINTER;
190 return false;
191 }
192
193 oop mirror = JNIHandles::resolve_non_null(_class_defs[i].klass);
194 // classes for primitives, arrays, and hidden classes
195 // cannot be redefined.
196 if (!is_modifiable_class(mirror)) {
197 _res = JVMTI_ERROR_UNMODIFIABLE_CLASS;
198 return false;
199 }
200 }
201
202 // Start timer after all the sanity checks; not quite accurate, but
203 // better than adding a bunch of stop() calls.
204 if (log_is_enabled(Info, redefine, class, timer)) {
205 _timer_vm_op_prologue.start();
206 }
207
208 lock_classes();
209 // We first load new class versions in the prologue, because somewhere down the
210 // call chain it is required that the current thread is a Java thread.
211 _res = load_new_class_versions();
212 if (_res != JVMTI_ERROR_NONE) {
213 // free any successfully created classes, since none are redefined
214 for (int i = 0; i < _class_count; i++) {
215 if (_scratch_classes[i] != nullptr) {
216 ClassLoaderData* cld = _scratch_classes[i]->class_loader_data();
217 // Free the memory for this class at class unloading time. Not before
218 // because CMS might think this is still live.
219 InstanceKlass* ik = get_ik(_class_defs[i].klass);
220 if (ik->get_cached_class_file() == _scratch_classes[i]->get_cached_class_file()) {
221 // Don't double-free cached_class_file copied from the original class if error.
222 _scratch_classes[i]->set_cached_class_file(nullptr);
223 }
224 cld->add_to_deallocate_list(InstanceKlass::cast(_scratch_classes[i]));
225 }
226 }
227 // Free os::malloc allocated memory in load_new_class_version.
228 os::free(_scratch_classes);
229 _timer_vm_op_prologue.stop();
230 unlock_classes();
231 return false;
232 }
233
234 _timer_vm_op_prologue.stop();
235 return true;
236 }
237
238 void VM_RedefineClasses::doit() {
239 Thread* current = Thread::current();
240
241 if (log_is_enabled(Info, redefine, class, timer)) {
242 _timer_vm_op_doit.start();
243 }
244
245 #if INCLUDE_CDS
246 if (UseSharedSpaces) {
247 // Sharing is enabled so we remap the shared readonly space to
248 // shared readwrite, private just in case we need to redefine
249 // a shared class. We do the remap during the doit() phase of
250 // the safepoint to be safer.
251 if (!MetaspaceShared::remap_shared_readonly_as_readwrite()) {
252 log_info(redefine, class, load)("failed to remap shared readonly space to readwrite, private");
253 _res = JVMTI_ERROR_INTERNAL;
254 _timer_vm_op_doit.stop();
255 return;
256 }
257 }
258 #endif
259
260 // Mark methods seen on stack and everywhere else so old methods are not
261 // cleaned up if they're on the stack.
262 MetadataOnStackMark md_on_stack(/*walk_all_metadata*/true, /*redefinition_walk*/true);
263 HandleMark hm(current); // make sure any handles created are deleted
264 // before the stack walk again.
265
266 for (int i = 0; i < _class_count; i++) {
267 redefine_single_class(current, _class_defs[i].klass, _scratch_classes[i]);
268 }
269
270 // Flush all compiled code that depends on the classes redefined.
271 flush_dependent_code();
272
273 // Adjust constantpool caches and vtables for all classes
274 // that reference methods of the evolved classes.
275 // Have to do this after all classes are redefined and all methods that
276 // are redefined are marked as old.
277 AdjustAndCleanMetadata adjust_and_clean_metadata(current);
278 ClassLoaderDataGraph::classes_do(&adjust_and_clean_metadata);
279
280 // JSR-292 support
281 if (_any_class_has_resolved_methods) {
282 bool trace_name_printed = false;
283 ResolvedMethodTable::adjust_method_entries(&trace_name_printed);
284 }
285
286 // Increment flag indicating that some invariants are no longer true.
287 // See jvmtiExport.hpp for detailed explanation.
288 JvmtiExport::increment_redefinition_count();
289
290 // check_class() is optionally called for product bits, but is
291 // always called for non-product bits.
292 #ifdef PRODUCT
293 if (log_is_enabled(Trace, redefine, class, obsolete, metadata)) {
294 #endif
295 log_trace(redefine, class, obsolete, metadata)("calling check_class");
296 CheckClass check_class(current);
297 ClassLoaderDataGraph::classes_do(&check_class);
298 #ifdef PRODUCT
299 }
300 #endif
301
302 // Clean up any metadata now unreferenced while MetadataOnStackMark is set.
303 ClassLoaderDataGraph::clean_deallocate_lists(false);
304
305 _timer_vm_op_doit.stop();
306 }
307
308 void VM_RedefineClasses::doit_epilogue() {
309 unlock_classes();
310
311 // Free os::malloc allocated memory.
312 os::free(_scratch_classes);
313
314 // Reset the_class to null for error printing.
315 _the_class = nullptr;
316
317 if (log_is_enabled(Info, redefine, class, timer)) {
318 // Used to have separate timers for "doit" and "all", but the timer
319 // overhead skewed the measurements.
320 julong doit_time = _timer_vm_op_doit.milliseconds();
321 julong all_time = _timer_vm_op_prologue.milliseconds() + doit_time;
322
323 log_info(redefine, class, timer)
324 ("vm_op: all=" JULONG_FORMAT " prologue=" JULONG_FORMAT " doit=" JULONG_FORMAT,
325 all_time, (julong)_timer_vm_op_prologue.milliseconds(), doit_time);
326 log_info(redefine, class, timer)
327 ("redefine_single_class: phase1=" JULONG_FORMAT " phase2=" JULONG_FORMAT,
328 (julong)_timer_rsc_phase1.milliseconds(), (julong)_timer_rsc_phase2.milliseconds());
329 }
330 }
331
332 bool VM_RedefineClasses::is_modifiable_class(oop klass_mirror) {
333 // classes for primitives cannot be redefined
334 if (java_lang_Class::is_primitive(klass_mirror)) {
335 return false;
336 }
337 Klass* k = java_lang_Class::as_Klass(klass_mirror);
338 // classes for arrays cannot be redefined
339 if (k == nullptr || !k->is_instance_klass()) {
340 return false;
341 }
342
343 // Cannot redefine or retransform a hidden class.
344 if (InstanceKlass::cast(k)->is_hidden()) {
345 return false;
346 }
347 if (InstanceKlass::cast(k) == vmClasses::Continuation_klass()) {
348 // Don't redefine Continuation class. See 8302779.
349 return false;
350 }
351 return true;
352 }
353
354 // Append the current entry at scratch_i in scratch_cp to *merge_cp_p
355 // where the end of *merge_cp_p is specified by *merge_cp_length_p. For
356 // direct CP entries, there is just the current entry to append. For
357 // indirect and double-indirect CP entries, there are zero or more
358 // referenced CP entries along with the current entry to append.
359 // Indirect and double-indirect CP entries are handled by recursive
360 // calls to append_entry() as needed. The referenced CP entries are
361 // always appended to *merge_cp_p before the referee CP entry. These
362 // referenced CP entries may already exist in *merge_cp_p in which case
363 // there is nothing extra to append and only the current entry is
364 // appended.
365 void VM_RedefineClasses::append_entry(const constantPoolHandle& scratch_cp,
366 int scratch_i, constantPoolHandle *merge_cp_p, int *merge_cp_length_p) {
367
368 // append is different depending on entry tag type
369 switch (scratch_cp->tag_at(scratch_i).value()) {
370
371 // The old verifier is implemented outside the VM. It loads classes,
372 // but does not resolve constant pool entries directly so we never
373 // see Class entries here with the old verifier. Similarly the old
374 // verifier does not like Class entries in the input constant pool.
375 // The split-verifier is implemented in the VM so it can optionally
376 // and directly resolve constant pool entries to load classes. The
377 // split-verifier can accept either Class entries or UnresolvedClass
378 // entries in the input constant pool. We revert the appended copy
379 // back to UnresolvedClass so that either verifier will be happy
380 // with the constant pool entry.
381 //
382 // this is an indirect CP entry so it needs special handling
383 case JVM_CONSTANT_Class:
384 case JVM_CONSTANT_UnresolvedClass:
385 {
386 int name_i = scratch_cp->klass_name_index_at(scratch_i);
387 int new_name_i = find_or_append_indirect_entry(scratch_cp, name_i, merge_cp_p,
388 merge_cp_length_p);
389
390 if (new_name_i != name_i) {
391 log_trace(redefine, class, constantpool)
392 ("Class entry@%d name_index change: %d to %d",
393 *merge_cp_length_p, name_i, new_name_i);
394 }
395
396 (*merge_cp_p)->temp_unresolved_klass_at_put(*merge_cp_length_p, new_name_i);
397 if (scratch_i != *merge_cp_length_p) {
398 // The new entry in *merge_cp_p is at a different index than
399 // the new entry in scratch_cp so we need to map the index values.
400 map_index(scratch_cp, scratch_i, *merge_cp_length_p);
401 }
402 (*merge_cp_length_p)++;
403 } break;
404
405 // these are direct CP entries so they can be directly appended,
406 // but double and long take two constant pool entries
407 case JVM_CONSTANT_Double: // fall through
408 case JVM_CONSTANT_Long:
409 {
410 ConstantPool::copy_entry_to(scratch_cp, scratch_i, *merge_cp_p, *merge_cp_length_p);
411
412 if (scratch_i != *merge_cp_length_p) {
413 // The new entry in *merge_cp_p is at a different index than
414 // the new entry in scratch_cp so we need to map the index values.
415 map_index(scratch_cp, scratch_i, *merge_cp_length_p);
416 }
417 (*merge_cp_length_p) += 2;
418 } break;
419
420 // these are direct CP entries so they can be directly appended
421 case JVM_CONSTANT_Float: // fall through
422 case JVM_CONSTANT_Integer: // fall through
423 case JVM_CONSTANT_Utf8: // fall through
424
425 // This was an indirect CP entry, but it has been changed into
426 // Symbol*s so this entry can be directly appended.
427 case JVM_CONSTANT_String: // fall through
428 {
429 ConstantPool::copy_entry_to(scratch_cp, scratch_i, *merge_cp_p, *merge_cp_length_p);
430
431 if (scratch_i != *merge_cp_length_p) {
432 // The new entry in *merge_cp_p is at a different index than
433 // the new entry in scratch_cp so we need to map the index values.
434 map_index(scratch_cp, scratch_i, *merge_cp_length_p);
435 }
436 (*merge_cp_length_p)++;
437 } break;
438
439 // this is an indirect CP entry so it needs special handling
440 case JVM_CONSTANT_NameAndType:
441 {
442 int name_ref_i = scratch_cp->name_ref_index_at(scratch_i);
443 int new_name_ref_i = find_or_append_indirect_entry(scratch_cp, name_ref_i, merge_cp_p,
444 merge_cp_length_p);
445
446 int signature_ref_i = scratch_cp->signature_ref_index_at(scratch_i);
447 int new_signature_ref_i = find_or_append_indirect_entry(scratch_cp, signature_ref_i,
448 merge_cp_p, merge_cp_length_p);
449
450 // If the referenced entries already exist in *merge_cp_p, then
451 // both new_name_ref_i and new_signature_ref_i will both be 0.
452 // In that case, all we are appending is the current entry.
453 if (new_name_ref_i != name_ref_i) {
454 log_trace(redefine, class, constantpool)
455 ("NameAndType entry@%d name_ref_index change: %d to %d",
456 *merge_cp_length_p, name_ref_i, new_name_ref_i);
457 }
458 if (new_signature_ref_i != signature_ref_i) {
459 log_trace(redefine, class, constantpool)
460 ("NameAndType entry@%d signature_ref_index change: %d to %d",
461 *merge_cp_length_p, signature_ref_i, new_signature_ref_i);
462 }
463
464 (*merge_cp_p)->name_and_type_at_put(*merge_cp_length_p,
465 new_name_ref_i, new_signature_ref_i);
466 if (scratch_i != *merge_cp_length_p) {
467 // The new entry in *merge_cp_p is at a different index than
468 // the new entry in scratch_cp so we need to map the index values.
469 map_index(scratch_cp, scratch_i, *merge_cp_length_p);
470 }
471 (*merge_cp_length_p)++;
472 } break;
473
474 // this is a double-indirect CP entry so it needs special handling
475 case JVM_CONSTANT_Fieldref: // fall through
476 case JVM_CONSTANT_InterfaceMethodref: // fall through
477 case JVM_CONSTANT_Methodref:
478 {
479 int klass_ref_i = scratch_cp->uncached_klass_ref_index_at(scratch_i);
480 int new_klass_ref_i = find_or_append_indirect_entry(scratch_cp, klass_ref_i,
481 merge_cp_p, merge_cp_length_p);
482
483 int name_and_type_ref_i = scratch_cp->uncached_name_and_type_ref_index_at(scratch_i);
484 int new_name_and_type_ref_i = find_or_append_indirect_entry(scratch_cp, name_and_type_ref_i,
485 merge_cp_p, merge_cp_length_p);
486
487 const char *entry_name = nullptr;
488 switch (scratch_cp->tag_at(scratch_i).value()) {
489 case JVM_CONSTANT_Fieldref:
490 entry_name = "Fieldref";
491 (*merge_cp_p)->field_at_put(*merge_cp_length_p, new_klass_ref_i,
492 new_name_and_type_ref_i);
493 break;
494 case JVM_CONSTANT_InterfaceMethodref:
495 entry_name = "IFMethodref";
496 (*merge_cp_p)->interface_method_at_put(*merge_cp_length_p,
497 new_klass_ref_i, new_name_and_type_ref_i);
498 break;
499 case JVM_CONSTANT_Methodref:
500 entry_name = "Methodref";
501 (*merge_cp_p)->method_at_put(*merge_cp_length_p, new_klass_ref_i,
502 new_name_and_type_ref_i);
503 break;
504 default:
505 guarantee(false, "bad switch");
506 break;
507 }
508
509 if (klass_ref_i != new_klass_ref_i) {
510 log_trace(redefine, class, constantpool)
511 ("%s entry@%d class_index changed: %d to %d", entry_name, *merge_cp_length_p, klass_ref_i, new_klass_ref_i);
512 }
513 if (name_and_type_ref_i != new_name_and_type_ref_i) {
514 log_trace(redefine, class, constantpool)
515 ("%s entry@%d name_and_type_index changed: %d to %d",
516 entry_name, *merge_cp_length_p, name_and_type_ref_i, new_name_and_type_ref_i);
517 }
518
519 if (scratch_i != *merge_cp_length_p) {
520 // The new entry in *merge_cp_p is at a different index than
521 // the new entry in scratch_cp so we need to map the index values.
522 map_index(scratch_cp, scratch_i, *merge_cp_length_p);
523 }
524 (*merge_cp_length_p)++;
525 } break;
526
527 // this is an indirect CP entry so it needs special handling
528 case JVM_CONSTANT_MethodType:
529 {
530 int ref_i = scratch_cp->method_type_index_at(scratch_i);
531 int new_ref_i = find_or_append_indirect_entry(scratch_cp, ref_i, merge_cp_p,
532 merge_cp_length_p);
533 if (new_ref_i != ref_i) {
534 log_trace(redefine, class, constantpool)
535 ("MethodType entry@%d ref_index change: %d to %d", *merge_cp_length_p, ref_i, new_ref_i);
536 }
537 (*merge_cp_p)->method_type_index_at_put(*merge_cp_length_p, new_ref_i);
538 if (scratch_i != *merge_cp_length_p) {
539 // The new entry in *merge_cp_p is at a different index than
540 // the new entry in scratch_cp so we need to map the index values.
541 map_index(scratch_cp, scratch_i, *merge_cp_length_p);
542 }
543 (*merge_cp_length_p)++;
544 } break;
545
546 // this is an indirect CP entry so it needs special handling
547 case JVM_CONSTANT_MethodHandle:
548 {
549 int ref_kind = scratch_cp->method_handle_ref_kind_at(scratch_i);
550 int ref_i = scratch_cp->method_handle_index_at(scratch_i);
551 int new_ref_i = find_or_append_indirect_entry(scratch_cp, ref_i, merge_cp_p,
552 merge_cp_length_p);
553 if (new_ref_i != ref_i) {
554 log_trace(redefine, class, constantpool)
555 ("MethodHandle entry@%d ref_index change: %d to %d", *merge_cp_length_p, ref_i, new_ref_i);
556 }
557 (*merge_cp_p)->method_handle_index_at_put(*merge_cp_length_p, ref_kind, new_ref_i);
558 if (scratch_i != *merge_cp_length_p) {
559 // The new entry in *merge_cp_p is at a different index than
560 // the new entry in scratch_cp so we need to map the index values.
561 map_index(scratch_cp, scratch_i, *merge_cp_length_p);
562 }
563 (*merge_cp_length_p)++;
564 } break;
565
566 // this is an indirect CP entry so it needs special handling
567 case JVM_CONSTANT_Dynamic: // fall through
568 case JVM_CONSTANT_InvokeDynamic:
569 {
570 // Index of the bootstrap specifier in the operands array
571 int old_bs_i = scratch_cp->bootstrap_methods_attribute_index(scratch_i);
572 int new_bs_i = find_or_append_operand(scratch_cp, old_bs_i, merge_cp_p,
573 merge_cp_length_p);
574 // The bootstrap method NameAndType_info index
575 int old_ref_i = scratch_cp->bootstrap_name_and_type_ref_index_at(scratch_i);
576 int new_ref_i = find_or_append_indirect_entry(scratch_cp, old_ref_i, merge_cp_p,
577 merge_cp_length_p);
578 if (new_bs_i != old_bs_i) {
579 log_trace(redefine, class, constantpool)
580 ("Dynamic entry@%d bootstrap_method_attr_index change: %d to %d",
581 *merge_cp_length_p, old_bs_i, new_bs_i);
582 }
583 if (new_ref_i != old_ref_i) {
584 log_trace(redefine, class, constantpool)
585 ("Dynamic entry@%d name_and_type_index change: %d to %d", *merge_cp_length_p, old_ref_i, new_ref_i);
586 }
587
588 if (scratch_cp->tag_at(scratch_i).is_dynamic_constant())
589 (*merge_cp_p)->dynamic_constant_at_put(*merge_cp_length_p, new_bs_i, new_ref_i);
590 else
591 (*merge_cp_p)->invoke_dynamic_at_put(*merge_cp_length_p, new_bs_i, new_ref_i);
592 if (scratch_i != *merge_cp_length_p) {
593 // The new entry in *merge_cp_p is at a different index than
594 // the new entry in scratch_cp so we need to map the index values.
595 map_index(scratch_cp, scratch_i, *merge_cp_length_p);
596 }
597 (*merge_cp_length_p)++;
598 } break;
599
600 // At this stage, Class or UnresolvedClass could be in scratch_cp, but not
601 // ClassIndex
602 case JVM_CONSTANT_ClassIndex: // fall through
603
604 // Invalid is used as the tag for the second constant pool entry
605 // occupied by JVM_CONSTANT_Double or JVM_CONSTANT_Long. It should
606 // not be seen by itself.
607 case JVM_CONSTANT_Invalid: // fall through
608
609 // At this stage, String could be here, but not StringIndex
610 case JVM_CONSTANT_StringIndex: // fall through
611
612 // At this stage JVM_CONSTANT_UnresolvedClassInError should not be here
613 case JVM_CONSTANT_UnresolvedClassInError: // fall through
614
615 default:
616 {
617 // leave a breadcrumb
618 jbyte bad_value = scratch_cp->tag_at(scratch_i).value();
619 ShouldNotReachHere();
620 } break;
621 } // end switch tag value
622 } // end append_entry()
623
624
625 u2 VM_RedefineClasses::find_or_append_indirect_entry(const constantPoolHandle& scratch_cp,
626 int ref_i, constantPoolHandle *merge_cp_p, int *merge_cp_length_p) {
627
628 int new_ref_i = ref_i;
629 bool match = (ref_i < *merge_cp_length_p) &&
630 scratch_cp->compare_entry_to(ref_i, *merge_cp_p, ref_i);
631
632 if (!match) {
633 // forward reference in *merge_cp_p or not a direct match
634 int found_i = scratch_cp->find_matching_entry(ref_i, *merge_cp_p);
635 if (found_i != 0) {
636 guarantee(found_i != ref_i, "compare_entry_to() and find_matching_entry() do not agree");
637 // Found a matching entry somewhere else in *merge_cp_p so just need a mapping entry.
638 new_ref_i = found_i;
639 map_index(scratch_cp, ref_i, found_i);
640 } else {
641 // no match found so we have to append this entry to *merge_cp_p
642 append_entry(scratch_cp, ref_i, merge_cp_p, merge_cp_length_p);
643 // The above call to append_entry() can only append one entry
644 // so the post call query of *merge_cp_length_p is only for
645 // the sake of consistency.
646 new_ref_i = *merge_cp_length_p - 1;
647 }
648 }
649
650 // constant pool indices are u2, unless the merged constant pool overflows which
651 // we don't check for.
652 return checked_cast<u2>(new_ref_i);
653 } // end find_or_append_indirect_entry()
654
655
656 // Append a bootstrap specifier into the merge_cp operands that is semantically equal
657 // to the scratch_cp operands bootstrap specifier passed by the old_bs_i index.
658 // Recursively append new merge_cp entries referenced by the new bootstrap specifier.
659 void VM_RedefineClasses::append_operand(const constantPoolHandle& scratch_cp, int old_bs_i,
660 constantPoolHandle *merge_cp_p, int *merge_cp_length_p) {
661
662 u2 old_ref_i = scratch_cp->operand_bootstrap_method_ref_index_at(old_bs_i);
663 u2 new_ref_i = find_or_append_indirect_entry(scratch_cp, old_ref_i, merge_cp_p,
664 merge_cp_length_p);
665 if (new_ref_i != old_ref_i) {
666 log_trace(redefine, class, constantpool)
667 ("operands entry@%d bootstrap method ref_index change: %d to %d", _operands_cur_length, old_ref_i, new_ref_i);
668 }
669
670 Array<u2>* merge_ops = (*merge_cp_p)->operands();
671 int new_bs_i = _operands_cur_length;
672 // We have _operands_cur_length == 0 when the merge_cp operands is empty yet.
673 // However, the operand_offset_at(0) was set in the extend_operands() call.
674 int new_base = (new_bs_i == 0) ? (*merge_cp_p)->operand_offset_at(0)
675 : (*merge_cp_p)->operand_next_offset_at(new_bs_i - 1);
676 u2 argc = scratch_cp->operand_argument_count_at(old_bs_i);
677
678 ConstantPool::operand_offset_at_put(merge_ops, _operands_cur_length, new_base);
679 merge_ops->at_put(new_base++, new_ref_i);
680 merge_ops->at_put(new_base++, argc);
681
682 for (int i = 0; i < argc; i++) {
683 u2 old_arg_ref_i = scratch_cp->operand_argument_index_at(old_bs_i, i);
684 u2 new_arg_ref_i = find_or_append_indirect_entry(scratch_cp, old_arg_ref_i, merge_cp_p,
685 merge_cp_length_p);
686 merge_ops->at_put(new_base++, new_arg_ref_i);
687 if (new_arg_ref_i != old_arg_ref_i) {
688 log_trace(redefine, class, constantpool)
689 ("operands entry@%d bootstrap method argument ref_index change: %d to %d",
690 _operands_cur_length, old_arg_ref_i, new_arg_ref_i);
691 }
692 }
693 if (old_bs_i != _operands_cur_length) {
694 // The bootstrap specifier in *merge_cp_p is at a different index than
695 // that in scratch_cp so we need to map the index values.
696 map_operand_index(old_bs_i, new_bs_i);
697 }
698 _operands_cur_length++;
699 } // end append_operand()
700
701
702 int VM_RedefineClasses::find_or_append_operand(const constantPoolHandle& scratch_cp,
703 int old_bs_i, constantPoolHandle *merge_cp_p, int *merge_cp_length_p) {
704
705 int new_bs_i = old_bs_i; // bootstrap specifier index
706 bool match = (old_bs_i < _operands_cur_length) &&
707 scratch_cp->compare_operand_to(old_bs_i, *merge_cp_p, old_bs_i);
708
709 if (!match) {
710 // forward reference in *merge_cp_p or not a direct match
711 int found_i = scratch_cp->find_matching_operand(old_bs_i, *merge_cp_p,
712 _operands_cur_length);
713 if (found_i != -1) {
714 guarantee(found_i != old_bs_i, "compare_operand_to() and find_matching_operand() disagree");
715 // found a matching operand somewhere else in *merge_cp_p so just need a mapping
716 new_bs_i = found_i;
717 map_operand_index(old_bs_i, found_i);
718 } else {
719 // no match found so we have to append this bootstrap specifier to *merge_cp_p
720 append_operand(scratch_cp, old_bs_i, merge_cp_p, merge_cp_length_p);
721 new_bs_i = _operands_cur_length - 1;
722 }
723 }
724 return new_bs_i;
725 } // end find_or_append_operand()
726
727
728 void VM_RedefineClasses::finalize_operands_merge(const constantPoolHandle& merge_cp, TRAPS) {
729 if (merge_cp->operands() == nullptr) {
730 return;
731 }
732 // Shrink the merge_cp operands
733 merge_cp->shrink_operands(_operands_cur_length, CHECK);
734
735 if (log_is_enabled(Trace, redefine, class, constantpool)) {
736 // don't want to loop unless we are tracing
737 int count = 0;
738 for (int i = 1; i < _operands_index_map_p->length(); i++) {
739 int value = _operands_index_map_p->at(i);
740 if (value != -1) {
741 log_trace(redefine, class, constantpool)("operands_index_map[%d]: old=%d new=%d", count, i, value);
742 count++;
743 }
744 }
745 }
746 // Clean-up
747 _operands_index_map_p = nullptr;
748 _operands_cur_length = 0;
749 _operands_index_map_count = 0;
750 } // end finalize_operands_merge()
751
752 // Symbol* comparator for qsort
753 // The caller must have an active ResourceMark.
754 static int symcmp(const void* a, const void* b) {
755 char* astr = (*(Symbol**)a)->as_C_string();
756 char* bstr = (*(Symbol**)b)->as_C_string();
757 return strcmp(astr, bstr);
758 }
759
760 // The caller must have an active ResourceMark.
761 static jvmtiError check_attribute_arrays(const char* attr_name,
762 InstanceKlass* the_class, InstanceKlass* scratch_class,
763 Array<u2>* the_array, Array<u2>* scr_array) {
764 bool the_array_exists = the_array != Universe::the_empty_short_array();
765 bool scr_array_exists = scr_array != Universe::the_empty_short_array();
766
767 int array_len = the_array->length();
768 if (the_array_exists && scr_array_exists) {
769 if (array_len != scr_array->length()) {
770 log_trace(redefine, class)
771 ("redefined class %s attribute change error: %s len=%d changed to len=%d",
772 the_class->external_name(), attr_name, array_len, scr_array->length());
773 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_CLASS_ATTRIBUTE_CHANGED;
774 }
775
776 // The order of entries in the attribute array is not specified so we
777 // have to explicitly check for the same contents. We do this by copying
778 // the referenced symbols into their own arrays, sorting them and then
779 // comparing each element pair.
780
781 Symbol** the_syms = NEW_RESOURCE_ARRAY_RETURN_NULL(Symbol*, array_len);
782 Symbol** scr_syms = NEW_RESOURCE_ARRAY_RETURN_NULL(Symbol*, array_len);
783
784 if (the_syms == nullptr || scr_syms == nullptr) {
785 return JVMTI_ERROR_OUT_OF_MEMORY;
786 }
787
788 for (int i = 0; i < array_len; i++) {
789 int the_cp_index = the_array->at(i);
790 int scr_cp_index = scr_array->at(i);
791 the_syms[i] = the_class->constants()->klass_name_at(the_cp_index);
792 scr_syms[i] = scratch_class->constants()->klass_name_at(scr_cp_index);
793 }
794
795 qsort(the_syms, array_len, sizeof(Symbol*), symcmp);
796 qsort(scr_syms, array_len, sizeof(Symbol*), symcmp);
797
798 for (int i = 0; i < array_len; i++) {
799 if (the_syms[i] != scr_syms[i]) {
800 log_info(redefine, class)
801 ("redefined class %s attribute change error: %s[%d]: %s changed to %s",
802 the_class->external_name(), attr_name, i,
803 the_syms[i]->as_C_string(), scr_syms[i]->as_C_string());
804 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_CLASS_ATTRIBUTE_CHANGED;
805 }
806 }
807 } else if (the_array_exists ^ scr_array_exists) {
808 const char* action_str = (the_array_exists) ? "removed" : "added";
809 log_info(redefine, class)
810 ("redefined class %s attribute change error: %s attribute %s",
811 the_class->external_name(), attr_name, action_str);
812 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_CLASS_ATTRIBUTE_CHANGED;
813 }
814 return JVMTI_ERROR_NONE;
815 }
816
817 static jvmtiError check_nest_attributes(InstanceKlass* the_class,
818 InstanceKlass* scratch_class) {
819 // Check whether the class NestHost attribute has been changed.
820 Thread* thread = Thread::current();
821 ResourceMark rm(thread);
822 u2 the_nest_host_idx = the_class->nest_host_index();
823 u2 scr_nest_host_idx = scratch_class->nest_host_index();
824
825 if (the_nest_host_idx != 0 && scr_nest_host_idx != 0) {
826 Symbol* the_sym = the_class->constants()->klass_name_at(the_nest_host_idx);
827 Symbol* scr_sym = scratch_class->constants()->klass_name_at(scr_nest_host_idx);
828 if (the_sym != scr_sym) {
829 log_info(redefine, class, nestmates)
830 ("redefined class %s attribute change error: NestHost class: %s replaced with: %s",
831 the_class->external_name(), the_sym->as_C_string(), scr_sym->as_C_string());
832 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_CLASS_ATTRIBUTE_CHANGED;
833 }
834 } else if ((the_nest_host_idx == 0) ^ (scr_nest_host_idx == 0)) {
835 const char* action_str = (the_nest_host_idx != 0) ? "removed" : "added";
836 log_info(redefine, class, nestmates)
837 ("redefined class %s attribute change error: NestHost attribute %s",
838 the_class->external_name(), action_str);
839 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_CLASS_ATTRIBUTE_CHANGED;
840 }
841
842 // Check whether the class NestMembers attribute has been changed.
843 return check_attribute_arrays("NestMembers",
844 the_class, scratch_class,
845 the_class->nest_members(),
846 scratch_class->nest_members());
847 }
848
849 // Return an error status if the class Record attribute was changed.
850 static jvmtiError check_record_attribute(InstanceKlass* the_class, InstanceKlass* scratch_class) {
851 // Get lists of record components.
852 Array<RecordComponent*>* the_record = the_class->record_components();
853 Array<RecordComponent*>* scr_record = scratch_class->record_components();
854 bool the_record_exists = the_record != nullptr;
855 bool scr_record_exists = scr_record != nullptr;
856
857 if (the_record_exists && scr_record_exists) {
858 int the_num_components = the_record->length();
859 int scr_num_components = scr_record->length();
860 if (the_num_components != scr_num_components) {
861 log_info(redefine, class, record)
862 ("redefined class %s attribute change error: Record num_components=%d changed to num_components=%d",
863 the_class->external_name(), the_num_components, scr_num_components);
864 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_CLASS_ATTRIBUTE_CHANGED;
865 }
866
867 // Compare each field in each record component.
868 ConstantPool* the_cp = the_class->constants();
869 ConstantPool* scr_cp = scratch_class->constants();
870 for (int x = 0; x < the_num_components; x++) {
871 RecordComponent* the_component = the_record->at(x);
872 RecordComponent* scr_component = scr_record->at(x);
873 const Symbol* const the_name = the_cp->symbol_at(the_component->name_index());
874 const Symbol* const scr_name = scr_cp->symbol_at(scr_component->name_index());
875 const Symbol* const the_descr = the_cp->symbol_at(the_component->descriptor_index());
876 const Symbol* const scr_descr = scr_cp->symbol_at(scr_component->descriptor_index());
877 if (the_name != scr_name || the_descr != scr_descr) {
878 log_info(redefine, class, record)
879 ("redefined class %s attribute change error: Record name_index, descriptor_index, and/or attributes_count changed",
880 the_class->external_name());
881 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_CLASS_ATTRIBUTE_CHANGED;
882 }
883
884 int the_gen_sig = the_component->generic_signature_index();
885 int scr_gen_sig = scr_component->generic_signature_index();
886 const Symbol* const the_gen_sig_sym = (the_gen_sig == 0 ? nullptr :
887 the_cp->symbol_at(the_component->generic_signature_index()));
888 const Symbol* const scr_gen_sig_sym = (scr_gen_sig == 0 ? nullptr :
889 scr_cp->symbol_at(scr_component->generic_signature_index()));
890 if (the_gen_sig_sym != scr_gen_sig_sym) {
891 log_info(redefine, class, record)
892 ("redefined class %s attribute change error: Record generic_signature attribute changed",
893 the_class->external_name());
894 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_CLASS_ATTRIBUTE_CHANGED;
895 }
896
897 // It's okay if a record component's annotations were changed.
898 }
899
900 } else if (the_record_exists ^ scr_record_exists) {
901 const char* action_str = (the_record_exists) ? "removed" : "added";
902 log_info(redefine, class, record)
903 ("redefined class %s attribute change error: Record attribute %s",
904 the_class->external_name(), action_str);
905 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_CLASS_ATTRIBUTE_CHANGED;
906 }
907
908 return JVMTI_ERROR_NONE;
909 }
910
911
912 static jvmtiError check_permitted_subclasses_attribute(InstanceKlass* the_class,
913 InstanceKlass* scratch_class) {
914 Thread* thread = Thread::current();
915 ResourceMark rm(thread);
916
917 // Check whether the class PermittedSubclasses attribute has been changed.
918 return check_attribute_arrays("PermittedSubclasses",
919 the_class, scratch_class,
920 the_class->permitted_subclasses(),
921 scratch_class->permitted_subclasses());
922 }
923
924 static jvmtiError check_preload_attribute(InstanceKlass* the_class,
925 InstanceKlass* scratch_class) {
926 Thread* thread = Thread::current();
927 ResourceMark rm(thread);
928
929 // Check whether the class Preload attribute has been changed.
930 return check_attribute_arrays("Preload",
931 the_class, scratch_class,
932 the_class->preload_classes(),
933 scratch_class->preload_classes());
934 }
935
936 static bool can_add_or_delete(Method* m) {
937 // Compatibility mode
938 return (AllowRedefinitionToAddDeleteMethods &&
939 (m->is_private() && (m->is_static() || m->is_final())));
940 }
941
942 jvmtiError VM_RedefineClasses::compare_and_normalize_class_versions(
943 InstanceKlass* the_class,
944 InstanceKlass* scratch_class) {
945 int i;
946
947 // Check superclasses, or rather their names, since superclasses themselves can be
948 // requested to replace.
949 // Check for null superclass first since this might be java.lang.Object
950 if (the_class->super() != scratch_class->super() &&
951 (the_class->super() == nullptr || scratch_class->super() == nullptr ||
952 the_class->super()->name() !=
953 scratch_class->super()->name())) {
954 log_info(redefine, class, normalize)
955 ("redefined class %s superclass change error: superclass changed from %s to %s.",
956 the_class->external_name(),
957 the_class->super() == nullptr ? "null" : the_class->super()->external_name(),
958 scratch_class->super() == nullptr ? "null" : scratch_class->super()->external_name());
959 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_HIERARCHY_CHANGED;
960 }
961
962 // Check if the number, names and order of directly implemented interfaces are the same.
963 // I think in principle we should just check if the sets of names of directly implemented
964 // interfaces are the same, i.e. the order of declaration (which, however, if changed in the
965 // .java file, also changes in .class file) should not matter. However, comparing sets is
966 // technically a bit more difficult, and, more importantly, I am not sure at present that the
967 // order of interfaces does not matter on the implementation level, i.e. that the VM does not
968 // rely on it somewhere.
969 Array<InstanceKlass*>* k_interfaces = the_class->local_interfaces();
970 Array<InstanceKlass*>* k_new_interfaces = scratch_class->local_interfaces();
971 int n_intfs = k_interfaces->length();
972 if (n_intfs != k_new_interfaces->length()) {
973 log_info(redefine, class, normalize)
974 ("redefined class %s interfaces change error: number of implemented interfaces changed from %d to %d.",
975 the_class->external_name(), n_intfs, k_new_interfaces->length());
976 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_HIERARCHY_CHANGED;
977 }
978 for (i = 0; i < n_intfs; i++) {
979 if (k_interfaces->at(i)->name() !=
980 k_new_interfaces->at(i)->name()) {
981 log_info(redefine, class, normalize)
982 ("redefined class %s interfaces change error: interface changed from %s to %s.",
983 the_class->external_name(),
984 k_interfaces->at(i)->external_name(), k_new_interfaces->at(i)->external_name());
985 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_HIERARCHY_CHANGED;
986 }
987 }
988
989 // Check whether class is in the error init state.
990 if (the_class->is_in_error_state()) {
991 log_info(redefine, class, normalize)
992 ("redefined class %s is in error init state.", the_class->external_name());
993 // TBD #5057930: special error code is needed in 1.6
994 return JVMTI_ERROR_INVALID_CLASS;
995 }
996
997 // Check whether the nest-related attributes have been changed.
998 jvmtiError err = check_nest_attributes(the_class, scratch_class);
999 if (err != JVMTI_ERROR_NONE) {
1000 return err;
1001 }
1002
1003 // Check whether the Record attribute has been changed.
1004 err = check_record_attribute(the_class, scratch_class);
1005 if (err != JVMTI_ERROR_NONE) {
1006 return err;
1007 }
1008
1009 // Check whether the PermittedSubclasses attribute has been changed.
1010 err = check_permitted_subclasses_attribute(the_class, scratch_class);
1011 if (err != JVMTI_ERROR_NONE) {
1012 return err;
1013 }
1014
1015 // Check whether the Preload attribute has been changed.
1016 err = check_preload_attribute(the_class, scratch_class);
1017 if (err != JVMTI_ERROR_NONE) {
1018 return err;
1019 }
1020
1021 // Check whether class modifiers are the same.
1022 jushort old_flags = (jushort) the_class->access_flags().get_flags();
1023 jushort new_flags = (jushort) scratch_class->access_flags().get_flags();
1024 if (old_flags != new_flags) {
1025 log_info(redefine, class, normalize)
1026 ("redefined class %s modifiers change error: modifiers changed from %d to %d.",
1027 the_class->external_name(), old_flags, new_flags);
1028 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_CLASS_MODIFIERS_CHANGED;
1029 }
1030
1031 // Check if the number, names, types and order of fields declared in these classes
1032 // are the same.
1033 JavaFieldStream old_fs(the_class);
1034 JavaFieldStream new_fs(scratch_class);
1035 for (; !old_fs.done() && !new_fs.done(); old_fs.next(), new_fs.next()) {
1036 // name and signature
1037 Symbol* name_sym1 = the_class->constants()->symbol_at(old_fs.name_index());
1038 Symbol* sig_sym1 = the_class->constants()->symbol_at(old_fs.signature_index());
1039 Symbol* name_sym2 = scratch_class->constants()->symbol_at(new_fs.name_index());
1040 Symbol* sig_sym2 = scratch_class->constants()->symbol_at(new_fs.signature_index());
1041 if (name_sym1 != name_sym2 || sig_sym1 != sig_sym2) {
1042 log_info(redefine, class, normalize)
1043 ("redefined class %s fields change error: field %s %s changed to %s %s.",
1044 the_class->external_name(),
1045 sig_sym1->as_C_string(), name_sym1->as_C_string(),
1046 sig_sym2->as_C_string(), name_sym2->as_C_string());
1047 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_SCHEMA_CHANGED;
1048 }
1049 // offset
1050 if (old_fs.offset() != new_fs.offset()) {
1051 log_info(redefine, class, normalize)
1052 ("redefined class %s field %s change error: offset changed from %d to %d.",
1053 the_class->external_name(), name_sym2->as_C_string(), old_fs.offset(), new_fs.offset());
1054 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_SCHEMA_CHANGED;
1055 }
1056 // access
1057 old_flags = old_fs.access_flags().as_short();
1058 new_flags = new_fs.access_flags().as_short();
1059 if ((old_flags ^ new_flags) & JVM_RECOGNIZED_FIELD_MODIFIERS) {
1060 log_info(redefine, class, normalize)
1061 ("redefined class %s field %s change error: modifiers changed from %d to %d.",
1062 the_class->external_name(), name_sym2->as_C_string(), old_flags, new_flags);
1063 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_SCHEMA_CHANGED;
1064 }
1065 }
1066
1067 // If both streams aren't done then we have a differing number of
1068 // fields.
1069 if (!old_fs.done() || !new_fs.done()) {
1070 const char* action = old_fs.done() ? "added" : "deleted";
1071 log_info(redefine, class, normalize)
1072 ("redefined class %s fields change error: some fields were %s.",
1073 the_class->external_name(), action);
1074 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_SCHEMA_CHANGED;
1075 }
1076
1077 // Do a parallel walk through the old and new methods. Detect
1078 // cases where they match (exist in both), have been added in
1079 // the new methods, or have been deleted (exist only in the
1080 // old methods). The class file parser places methods in order
1081 // by method name, but does not order overloaded methods by
1082 // signature. In order to determine what fate befell the methods,
1083 // this code places the overloaded new methods that have matching
1084 // old methods in the same order as the old methods and places
1085 // new overloaded methods at the end of overloaded methods of
1086 // that name. The code for this order normalization is adapted
1087 // from the algorithm used in InstanceKlass::find_method().
1088 // Since we are swapping out of order entries as we find them,
1089 // we only have to search forward through the overloaded methods.
1090 // Methods which are added and have the same name as an existing
1091 // method (but different signature) will be put at the end of
1092 // the methods with that name, and the name mismatch code will
1093 // handle them.
1094 Array<Method*>* k_old_methods(the_class->methods());
1095 Array<Method*>* k_new_methods(scratch_class->methods());
1096 int n_old_methods = k_old_methods->length();
1097 int n_new_methods = k_new_methods->length();
1098 Thread* thread = Thread::current();
1099
1100 int ni = 0;
1101 int oi = 0;
1102 while (true) {
1103 Method* k_old_method;
1104 Method* k_new_method;
1105 enum { matched, added, deleted, undetermined } method_was = undetermined;
1106
1107 if (oi >= n_old_methods) {
1108 if (ni >= n_new_methods) {
1109 break; // we've looked at everything, done
1110 }
1111 // New method at the end
1112 k_new_method = k_new_methods->at(ni);
1113 method_was = added;
1114 } else if (ni >= n_new_methods) {
1115 // Old method, at the end, is deleted
1116 k_old_method = k_old_methods->at(oi);
1117 method_was = deleted;
1118 } else {
1119 // There are more methods in both the old and new lists
1120 k_old_method = k_old_methods->at(oi);
1121 k_new_method = k_new_methods->at(ni);
1122 if (k_old_method->name() != k_new_method->name()) {
1123 // Methods are sorted by method name, so a mismatch means added
1124 // or deleted
1125 if (k_old_method->name()->fast_compare(k_new_method->name()) > 0) {
1126 method_was = added;
1127 } else {
1128 method_was = deleted;
1129 }
1130 } else if (k_old_method->signature() == k_new_method->signature()) {
1131 // Both the name and signature match
1132 method_was = matched;
1133 } else {
1134 // The name matches, but the signature doesn't, which means we have to
1135 // search forward through the new overloaded methods.
1136 int nj; // outside the loop for post-loop check
1137 for (nj = ni + 1; nj < n_new_methods; nj++) {
1138 Method* m = k_new_methods->at(nj);
1139 if (k_old_method->name() != m->name()) {
1140 // reached another method name so no more overloaded methods
1141 method_was = deleted;
1142 break;
1143 }
1144 if (k_old_method->signature() == m->signature()) {
1145 // found a match so swap the methods
1146 k_new_methods->at_put(ni, m);
1147 k_new_methods->at_put(nj, k_new_method);
1148 k_new_method = m;
1149 method_was = matched;
1150 break;
1151 }
1152 }
1153
1154 if (nj >= n_new_methods) {
1155 // reached the end without a match; so method was deleted
1156 method_was = deleted;
1157 }
1158 }
1159 }
1160
1161 switch (method_was) {
1162 case matched:
1163 // methods match, be sure modifiers do too
1164 old_flags = (jushort) k_old_method->access_flags().get_flags();
1165 new_flags = (jushort) k_new_method->access_flags().get_flags();
1166 if ((old_flags ^ new_flags) & ~(JVM_ACC_NATIVE)) {
1167 log_info(redefine, class, normalize)
1168 ("redefined class %s method %s modifiers error: modifiers changed from %d to %d",
1169 the_class->external_name(), k_old_method->name_and_sig_as_C_string(), old_flags, new_flags);
1170 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_METHOD_MODIFIERS_CHANGED;
1171 }
1172 {
1173 u2 new_num = k_new_method->method_idnum();
1174 u2 old_num = k_old_method->method_idnum();
1175 if (new_num != old_num) {
1176 Method* idnum_owner = scratch_class->method_with_idnum(old_num);
1177 if (idnum_owner != nullptr) {
1178 // There is already a method assigned this idnum -- switch them
1179 // Take current and original idnum from the new_method
1180 idnum_owner->set_method_idnum(new_num);
1181 idnum_owner->set_orig_method_idnum(k_new_method->orig_method_idnum());
1182 }
1183 // Take current and original idnum from the old_method
1184 k_new_method->set_method_idnum(old_num);
1185 k_new_method->set_orig_method_idnum(k_old_method->orig_method_idnum());
1186 if (thread->has_pending_exception()) {
1187 return JVMTI_ERROR_OUT_OF_MEMORY;
1188 }
1189 }
1190 }
1191 log_trace(redefine, class, normalize)
1192 ("Method matched: new: %s [%d] == old: %s [%d]",
1193 k_new_method->name_and_sig_as_C_string(), ni, k_old_method->name_and_sig_as_C_string(), oi);
1194 // advance to next pair of methods
1195 ++oi;
1196 ++ni;
1197 break;
1198 case added:
1199 // method added, see if it is OK
1200 if (!can_add_or_delete(k_new_method)) {
1201 log_info(redefine, class, normalize)
1202 ("redefined class %s methods error: added method: %s [%d]",
1203 the_class->external_name(), k_new_method->name_and_sig_as_C_string(), ni);
1204 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_METHOD_ADDED;
1205 }
1206 {
1207 u2 num = the_class->next_method_idnum();
1208 if (num == ConstMethod::UNSET_IDNUM) {
1209 // cannot add any more methods
1210 log_info(redefine, class, normalize)
1211 ("redefined class %s methods error: can't create ID for new method %s [%d]",
1212 the_class->external_name(), k_new_method->name_and_sig_as_C_string(), ni);
1213 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_METHOD_ADDED;
1214 }
1215 u2 new_num = k_new_method->method_idnum();
1216 Method* idnum_owner = scratch_class->method_with_idnum(num);
1217 if (idnum_owner != nullptr) {
1218 // There is already a method assigned this idnum -- switch them
1219 // Take current and original idnum from the new_method
1220 idnum_owner->set_method_idnum(new_num);
1221 idnum_owner->set_orig_method_idnum(k_new_method->orig_method_idnum());
1222 }
1223 k_new_method->set_method_idnum(num);
1224 k_new_method->set_orig_method_idnum(num);
1225 if (thread->has_pending_exception()) {
1226 return JVMTI_ERROR_OUT_OF_MEMORY;
1227 }
1228 }
1229 log_trace(redefine, class, normalize)
1230 ("Method added: new: %s [%d]", k_new_method->name_and_sig_as_C_string(), ni);
1231 ++ni; // advance to next new method
1232 break;
1233 case deleted:
1234 // method deleted, see if it is OK
1235 if (!can_add_or_delete(k_old_method)) {
1236 log_info(redefine, class, normalize)
1237 ("redefined class %s methods error: deleted method %s [%d]",
1238 the_class->external_name(), k_old_method->name_and_sig_as_C_string(), oi);
1239 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_METHOD_DELETED;
1240 }
1241 log_trace(redefine, class, normalize)
1242 ("Method deleted: old: %s [%d]", k_old_method->name_and_sig_as_C_string(), oi);
1243 ++oi; // advance to next old method
1244 break;
1245 default:
1246 ShouldNotReachHere();
1247 }
1248 }
1249
1250 return JVMTI_ERROR_NONE;
1251 }
1252
1253
1254 // Find new constant pool index value for old constant pool index value
1255 // by searching the index map. Returns zero (0) if there is no mapped
1256 // value for the old constant pool index.
1257 u2 VM_RedefineClasses::find_new_index(int old_index) {
1258 if (_index_map_count == 0) {
1259 // map is empty so nothing can be found
1260 return 0;
1261 }
1262
1263 if (old_index < 1 || old_index >= _index_map_p->length()) {
1264 // The old_index is out of range so it is not mapped. This should
1265 // not happen in regular constant pool merging use, but it can
1266 // happen if a corrupt annotation is processed.
1267 return 0;
1268 }
1269
1270 int value = _index_map_p->at(old_index);
1271 if (value == -1) {
1272 // the old_index is not mapped
1273 return 0;
1274 }
1275
1276 // constant pool indices are u2, unless the merged constant pool overflows which
1277 // we don't check for.
1278 return checked_cast<u2>(value);
1279 } // end find_new_index()
1280
1281
1282 // Find new bootstrap specifier index value for old bootstrap specifier index
1283 // value by searching the index map. Returns unused index (-1) if there is
1284 // no mapped value for the old bootstrap specifier index.
1285 int VM_RedefineClasses::find_new_operand_index(int old_index) {
1286 if (_operands_index_map_count == 0) {
1287 // map is empty so nothing can be found
1288 return -1;
1289 }
1290
1291 if (old_index == -1 || old_index >= _operands_index_map_p->length()) {
1292 // The old_index is out of range so it is not mapped.
1293 // This should not happen in regular constant pool merging use.
1294 return -1;
1295 }
1296
1297 int value = _operands_index_map_p->at(old_index);
1298 if (value == -1) {
1299 // the old_index is not mapped
1300 return -1;
1301 }
1302
1303 return value;
1304 } // end find_new_operand_index()
1305
1306
1307 // The bug 6214132 caused the verification to fail.
1308 // 1. What's done in RedefineClasses() before verification:
1309 // a) A reference to the class being redefined (_the_class) and a
1310 // reference to new version of the class (_scratch_class) are
1311 // saved here for use during the bytecode verification phase of
1312 // RedefineClasses.
1313 // b) The _java_mirror field from _the_class is copied to the
1314 // _java_mirror field in _scratch_class. This means that a jclass
1315 // returned for _the_class or _scratch_class will refer to the
1316 // same Java mirror. The verifier will see the "one true mirror"
1317 // for the class being verified.
1318 // 2. See comments in JvmtiThreadState for what is done during verification.
1319
1320 class RedefineVerifyMark : public StackObj {
1321 private:
1322 JvmtiThreadState* _state;
1323 Klass* _scratch_class;
1324 OopHandle _scratch_mirror;
1325
1326 public:
1327
1328 RedefineVerifyMark(Klass* the_class, Klass* scratch_class,
1329 JvmtiThreadState* state) : _state(state), _scratch_class(scratch_class)
1330 {
1331 _state->set_class_versions_map(the_class, scratch_class);
1332 _scratch_mirror = the_class->java_mirror_handle(); // this is a copy that is swapped
1333 _scratch_class->swap_java_mirror_handle(_scratch_mirror);
1334 }
1335
1336 ~RedefineVerifyMark() {
1337 // Restore the scratch class's mirror, so when scratch_class is removed
1338 // the correct mirror pointing to it can be cleared.
1339 _scratch_class->swap_java_mirror_handle(_scratch_mirror);
1340 _state->clear_class_versions_map();
1341 }
1342 };
1343
1344
1345 jvmtiError VM_RedefineClasses::load_new_class_versions() {
1346
1347 // For consistency allocate memory using os::malloc wrapper.
1348 _scratch_classes = (InstanceKlass**)
1349 os::malloc(sizeof(InstanceKlass*) * _class_count, mtClass);
1350 if (_scratch_classes == nullptr) {
1351 return JVMTI_ERROR_OUT_OF_MEMORY;
1352 }
1353 // Zero initialize the _scratch_classes array.
1354 for (int i = 0; i < _class_count; i++) {
1355 _scratch_classes[i] = nullptr;
1356 }
1357
1358 JavaThread* current = JavaThread::current();
1359 ResourceMark rm(current);
1360
1361 JvmtiThreadState *state = JvmtiThreadState::state_for(current);
1362 // state can only be null if the current thread is exiting which
1363 // should not happen since we're trying to do a RedefineClasses
1364 guarantee(state != nullptr, "exiting thread calling load_new_class_versions");
1365 for (int i = 0; i < _class_count; i++) {
1366 // Create HandleMark so that any handles created while loading new class
1367 // versions are deleted. Constant pools are deallocated while merging
1368 // constant pools
1369 HandleMark hm(current);
1370 InstanceKlass* the_class = get_ik(_class_defs[i].klass);
1371
1372 log_debug(redefine, class, load)
1373 ("loading name=%s kind=%d (avail_mem=" UINT64_FORMAT "K)",
1374 the_class->external_name(), _class_load_kind, os::available_memory() >> 10);
1375
1376 ClassFileStream st((u1*)_class_defs[i].class_bytes,
1377 _class_defs[i].class_byte_count,
1378 "__VM_RedefineClasses__",
1379 ClassFileStream::verify);
1380
1381 // Set redefined class handle in JvmtiThreadState class.
1382 // This redefined class is sent to agent event handler for class file
1383 // load hook event.
1384 state->set_class_being_redefined(the_class, _class_load_kind);
1385
1386 JavaThread* THREAD = current; // For exception macros.
1387 ExceptionMark em(THREAD);
1388 Handle protection_domain(THREAD, the_class->protection_domain());
1389 ClassLoadInfo cl_info(protection_domain);
1390 // Parse and create a class from the bytes, but this class isn't added
1391 // to the dictionary, so do not call resolve_from_stream.
1392 InstanceKlass* scratch_class = KlassFactory::create_from_stream(&st,
1393 the_class->name(),
1394 the_class->class_loader_data(),
1395 cl_info,
1396 THREAD);
1397
1398 // Clear class_being_redefined just to be sure.
1399 state->clear_class_being_redefined();
1400
1401 // TODO: if this is retransform, and nothing changed we can skip it
1402
1403 // Need to clean up allocated InstanceKlass if there's an error so assign
1404 // the result here. Caller deallocates all the scratch classes in case of
1405 // an error.
1406 _scratch_classes[i] = scratch_class;
1407
1408 if (HAS_PENDING_EXCEPTION) {
1409 Symbol* ex_name = PENDING_EXCEPTION->klass()->name();
1410 log_info(redefine, class, load, exceptions)("create_from_stream exception: '%s'", ex_name->as_C_string());
1411 CLEAR_PENDING_EXCEPTION;
1412
1413 if (ex_name == vmSymbols::java_lang_UnsupportedClassVersionError()) {
1414 return JVMTI_ERROR_UNSUPPORTED_VERSION;
1415 } else if (ex_name == vmSymbols::java_lang_ClassFormatError()) {
1416 return JVMTI_ERROR_INVALID_CLASS_FORMAT;
1417 } else if (ex_name == vmSymbols::java_lang_ClassCircularityError()) {
1418 return JVMTI_ERROR_CIRCULAR_CLASS_DEFINITION;
1419 } else if (ex_name == vmSymbols::java_lang_NoClassDefFoundError()) {
1420 // The message will be "XXX (wrong name: YYY)"
1421 return JVMTI_ERROR_NAMES_DONT_MATCH;
1422 } else if (ex_name == vmSymbols::java_lang_OutOfMemoryError()) {
1423 return JVMTI_ERROR_OUT_OF_MEMORY;
1424 } else { // Just in case more exceptions can be thrown..
1425 return JVMTI_ERROR_FAILS_VERIFICATION;
1426 }
1427 }
1428
1429 // Ensure class is linked before redefine
1430 if (!the_class->is_linked()) {
1431 the_class->link_class(THREAD);
1432 if (HAS_PENDING_EXCEPTION) {
1433 Symbol* ex_name = PENDING_EXCEPTION->klass()->name();
1434 oop message = java_lang_Throwable::message(PENDING_EXCEPTION);
1435 if (message != nullptr) {
1436 char* ex_msg = java_lang_String::as_utf8_string(message);
1437 log_info(redefine, class, load, exceptions)("link_class exception: '%s %s'",
1438 ex_name->as_C_string(), ex_msg);
1439 } else {
1440 log_info(redefine, class, load, exceptions)("link_class exception: '%s'",
1441 ex_name->as_C_string());
1442 }
1443 CLEAR_PENDING_EXCEPTION;
1444 if (ex_name == vmSymbols::java_lang_OutOfMemoryError()) {
1445 return JVMTI_ERROR_OUT_OF_MEMORY;
1446 } else if (ex_name == vmSymbols::java_lang_NoClassDefFoundError()) {
1447 return JVMTI_ERROR_INVALID_CLASS;
1448 } else {
1449 return JVMTI_ERROR_INTERNAL;
1450 }
1451 }
1452 }
1453
1454 // Do the validity checks in compare_and_normalize_class_versions()
1455 // before verifying the byte codes. By doing these checks first, we
1456 // limit the number of functions that require redirection from
1457 // the_class to scratch_class. In particular, we don't have to
1458 // modify JNI GetSuperclass() and thus won't change its performance.
1459 jvmtiError res = compare_and_normalize_class_versions(the_class,
1460 scratch_class);
1461 if (res != JVMTI_ERROR_NONE) {
1462 return res;
1463 }
1464
1465 // verify what the caller passed us
1466 {
1467 // The bug 6214132 caused the verification to fail.
1468 // Information about the_class and scratch_class is temporarily
1469 // recorded into jvmtiThreadState. This data is used to redirect
1470 // the_class to scratch_class in the JVM_* functions called by the
1471 // verifier. Please, refer to jvmtiThreadState.hpp for the detailed
1472 // description.
1473 RedefineVerifyMark rvm(the_class, scratch_class, state);
1474 Verifier::verify(scratch_class, true, THREAD);
1475 }
1476
1477 if (HAS_PENDING_EXCEPTION) {
1478 Symbol* ex_name = PENDING_EXCEPTION->klass()->name();
1479 log_info(redefine, class, load, exceptions)("verify_byte_codes exception: '%s'", ex_name->as_C_string());
1480 CLEAR_PENDING_EXCEPTION;
1481 if (ex_name == vmSymbols::java_lang_OutOfMemoryError()) {
1482 return JVMTI_ERROR_OUT_OF_MEMORY;
1483 } else {
1484 // tell the caller the bytecodes are bad
1485 return JVMTI_ERROR_FAILS_VERIFICATION;
1486 }
1487 }
1488
1489 res = merge_cp_and_rewrite(the_class, scratch_class, THREAD);
1490 if (HAS_PENDING_EXCEPTION) {
1491 Symbol* ex_name = PENDING_EXCEPTION->klass()->name();
1492 log_info(redefine, class, load, exceptions)("merge_cp_and_rewrite exception: '%s'", ex_name->as_C_string());
1493 CLEAR_PENDING_EXCEPTION;
1494 if (ex_name == vmSymbols::java_lang_OutOfMemoryError()) {
1495 return JVMTI_ERROR_OUT_OF_MEMORY;
1496 } else {
1497 return JVMTI_ERROR_INTERNAL;
1498 }
1499 }
1500
1501 #ifdef ASSERT
1502 {
1503 // verify what we have done during constant pool merging
1504 {
1505 RedefineVerifyMark rvm(the_class, scratch_class, state);
1506 Verifier::verify(scratch_class, true, THREAD);
1507 }
1508
1509 if (HAS_PENDING_EXCEPTION) {
1510 Symbol* ex_name = PENDING_EXCEPTION->klass()->name();
1511 log_info(redefine, class, load, exceptions)
1512 ("verify_byte_codes post merge-CP exception: '%s'", ex_name->as_C_string());
1513 CLEAR_PENDING_EXCEPTION;
1514 if (ex_name == vmSymbols::java_lang_OutOfMemoryError()) {
1515 return JVMTI_ERROR_OUT_OF_MEMORY;
1516 } else {
1517 // tell the caller that constant pool merging screwed up
1518 return JVMTI_ERROR_INTERNAL;
1519 }
1520 }
1521 }
1522 #endif // ASSERT
1523
1524 Rewriter::rewrite(scratch_class, THREAD);
1525 if (!HAS_PENDING_EXCEPTION) {
1526 scratch_class->link_methods(THREAD);
1527 }
1528 if (HAS_PENDING_EXCEPTION) {
1529 Symbol* ex_name = PENDING_EXCEPTION->klass()->name();
1530 log_info(redefine, class, load, exceptions)
1531 ("Rewriter::rewrite or link_methods exception: '%s'", ex_name->as_C_string());
1532 CLEAR_PENDING_EXCEPTION;
1533 if (ex_name == vmSymbols::java_lang_OutOfMemoryError()) {
1534 return JVMTI_ERROR_OUT_OF_MEMORY;
1535 } else {
1536 return JVMTI_ERROR_INTERNAL;
1537 }
1538 }
1539
1540 log_debug(redefine, class, load)
1541 ("loaded name=%s (avail_mem=" UINT64_FORMAT "K)", the_class->external_name(), os::available_memory() >> 10);
1542 }
1543
1544 return JVMTI_ERROR_NONE;
1545 }
1546
1547
1548 // Map old_index to new_index as needed. scratch_cp is only needed
1549 // for log calls.
1550 void VM_RedefineClasses::map_index(const constantPoolHandle& scratch_cp,
1551 int old_index, int new_index) {
1552 if (find_new_index(old_index) != 0) {
1553 // old_index is already mapped
1554 return;
1555 }
1556
1557 if (old_index == new_index) {
1558 // no mapping is needed
1559 return;
1560 }
1561
1562 _index_map_p->at_put(old_index, new_index);
1563 _index_map_count++;
1564
1565 log_trace(redefine, class, constantpool)
1566 ("mapped tag %d at index %d to %d", scratch_cp->tag_at(old_index).value(), old_index, new_index);
1567 } // end map_index()
1568
1569
1570 // Map old_index to new_index as needed.
1571 void VM_RedefineClasses::map_operand_index(int old_index, int new_index) {
1572 if (find_new_operand_index(old_index) != -1) {
1573 // old_index is already mapped
1574 return;
1575 }
1576
1577 if (old_index == new_index) {
1578 // no mapping is needed
1579 return;
1580 }
1581
1582 _operands_index_map_p->at_put(old_index, new_index);
1583 _operands_index_map_count++;
1584
1585 log_trace(redefine, class, constantpool)("mapped bootstrap specifier at index %d to %d", old_index, new_index);
1586 } // end map_index()
1587
1588
1589 // Merge old_cp and scratch_cp and return the results of the merge via
1590 // merge_cp_p. The number of entries in *merge_cp_p is returned via
1591 // merge_cp_length_p. The entries in old_cp occupy the same locations
1592 // in *merge_cp_p. Also creates a map of indices from entries in
1593 // scratch_cp to the corresponding entry in *merge_cp_p. Index map
1594 // entries are only created for entries in scratch_cp that occupy a
1595 // different location in *merged_cp_p.
1596 bool VM_RedefineClasses::merge_constant_pools(const constantPoolHandle& old_cp,
1597 const constantPoolHandle& scratch_cp, constantPoolHandle *merge_cp_p,
1598 int *merge_cp_length_p, TRAPS) {
1599
1600 if (merge_cp_p == nullptr) {
1601 assert(false, "caller must provide scratch constantPool");
1602 return false; // robustness
1603 }
1604 if (merge_cp_length_p == nullptr) {
1605 assert(false, "caller must provide scratch CP length");
1606 return false; // robustness
1607 }
1608 // Worst case we need old_cp->length() + scratch_cp()->length(),
1609 // but the caller might be smart so make sure we have at least
1610 // the minimum.
1611 if ((*merge_cp_p)->length() < old_cp->length()) {
1612 assert(false, "merge area too small");
1613 return false; // robustness
1614 }
1615
1616 log_info(redefine, class, constantpool)("old_cp_len=%d, scratch_cp_len=%d", old_cp->length(), scratch_cp->length());
1617
1618 {
1619 // Pass 0:
1620 // The old_cp is copied to *merge_cp_p; this means that any code
1621 // using old_cp does not have to change. This work looks like a
1622 // perfect fit for ConstantPool*::copy_cp_to(), but we need to
1623 // handle one special case:
1624 // - revert JVM_CONSTANT_Class to JVM_CONSTANT_UnresolvedClass
1625 // This will make verification happy.
1626
1627 int old_i; // index into old_cp
1628
1629 // index zero (0) is not used in constantPools
1630 for (old_i = 1; old_i < old_cp->length(); old_i++) {
1631 // leave debugging crumb
1632 jbyte old_tag = old_cp->tag_at(old_i).value();
1633 switch (old_tag) {
1634 case JVM_CONSTANT_Class:
1635 case JVM_CONSTANT_UnresolvedClass:
1636 // revert the copy to JVM_CONSTANT_UnresolvedClass
1637 // May be resolving while calling this so do the same for
1638 // JVM_CONSTANT_UnresolvedClass (klass_name_at() deals with transition)
1639 (*merge_cp_p)->temp_unresolved_klass_at_put(old_i,
1640 old_cp->klass_name_index_at(old_i));
1641 break;
1642
1643 case JVM_CONSTANT_Double:
1644 case JVM_CONSTANT_Long:
1645 // just copy the entry to *merge_cp_p, but double and long take
1646 // two constant pool entries
1647 ConstantPool::copy_entry_to(old_cp, old_i, *merge_cp_p, old_i);
1648 old_i++;
1649 break;
1650
1651 default:
1652 // just copy the entry to *merge_cp_p
1653 ConstantPool::copy_entry_to(old_cp, old_i, *merge_cp_p, old_i);
1654 break;
1655 }
1656 } // end for each old_cp entry
1657
1658 ConstantPool::copy_operands(old_cp, *merge_cp_p, CHECK_false);
1659 (*merge_cp_p)->extend_operands(scratch_cp, CHECK_false);
1660
1661 // We don't need to sanity check that *merge_cp_length_p is within
1662 // *merge_cp_p bounds since we have the minimum on-entry check above.
1663 (*merge_cp_length_p) = old_i;
1664 }
1665
1666 // merge_cp_len should be the same as old_cp->length() at this point
1667 // so this trace message is really a "warm-and-breathing" message.
1668 log_debug(redefine, class, constantpool)("after pass 0: merge_cp_len=%d", *merge_cp_length_p);
1669
1670 int scratch_i; // index into scratch_cp
1671 {
1672 // Pass 1a:
1673 // Compare scratch_cp entries to the old_cp entries that we have
1674 // already copied to *merge_cp_p. In this pass, we are eliminating
1675 // exact duplicates (matching entry at same index) so we only
1676 // compare entries in the common indice range.
1677 int increment = 1;
1678 int pass1a_length = MIN2(old_cp->length(), scratch_cp->length());
1679 for (scratch_i = 1; scratch_i < pass1a_length; scratch_i += increment) {
1680 switch (scratch_cp->tag_at(scratch_i).value()) {
1681 case JVM_CONSTANT_Double:
1682 case JVM_CONSTANT_Long:
1683 // double and long take two constant pool entries
1684 increment = 2;
1685 break;
1686
1687 default:
1688 increment = 1;
1689 break;
1690 }
1691
1692 bool match = scratch_cp->compare_entry_to(scratch_i, *merge_cp_p, scratch_i);
1693 if (match) {
1694 // found a match at the same index so nothing more to do
1695 continue;
1696 }
1697
1698 int found_i = scratch_cp->find_matching_entry(scratch_i, *merge_cp_p);
1699 if (found_i != 0) {
1700 guarantee(found_i != scratch_i,
1701 "compare_entry_to() and find_matching_entry() do not agree");
1702
1703 // Found a matching entry somewhere else in *merge_cp_p so
1704 // just need a mapping entry.
1705 map_index(scratch_cp, scratch_i, found_i);
1706 continue;
1707 }
1708
1709 // No match found so we have to append this entry and any unique
1710 // referenced entries to *merge_cp_p.
1711 append_entry(scratch_cp, scratch_i, merge_cp_p, merge_cp_length_p);
1712 }
1713 }
1714
1715 log_debug(redefine, class, constantpool)
1716 ("after pass 1a: merge_cp_len=%d, scratch_i=%d, index_map_len=%d",
1717 *merge_cp_length_p, scratch_i, _index_map_count);
1718
1719 if (scratch_i < scratch_cp->length()) {
1720 // Pass 1b:
1721 // old_cp is smaller than scratch_cp so there are entries in
1722 // scratch_cp that we have not yet processed. We take care of
1723 // those now.
1724 int increment = 1;
1725 for (; scratch_i < scratch_cp->length(); scratch_i += increment) {
1726 switch (scratch_cp->tag_at(scratch_i).value()) {
1727 case JVM_CONSTANT_Double:
1728 case JVM_CONSTANT_Long:
1729 // double and long take two constant pool entries
1730 increment = 2;
1731 break;
1732
1733 default:
1734 increment = 1;
1735 break;
1736 }
1737
1738 int found_i =
1739 scratch_cp->find_matching_entry(scratch_i, *merge_cp_p);
1740 if (found_i != 0) {
1741 // Found a matching entry somewhere else in *merge_cp_p so
1742 // just need a mapping entry.
1743 map_index(scratch_cp, scratch_i, found_i);
1744 continue;
1745 }
1746
1747 // No match found so we have to append this entry and any unique
1748 // referenced entries to *merge_cp_p.
1749 append_entry(scratch_cp, scratch_i, merge_cp_p, merge_cp_length_p);
1750 }
1751
1752 log_debug(redefine, class, constantpool)
1753 ("after pass 1b: merge_cp_len=%d, scratch_i=%d, index_map_len=%d",
1754 *merge_cp_length_p, scratch_i, _index_map_count);
1755 }
1756 finalize_operands_merge(*merge_cp_p, CHECK_false);
1757
1758 return true;
1759 } // end merge_constant_pools()
1760
1761
1762 // Scoped object to clean up the constant pool(s) created for merging
1763 class MergeCPCleaner {
1764 ClassLoaderData* _loader_data;
1765 ConstantPool* _cp;
1766 ConstantPool* _scratch_cp;
1767 public:
1768 MergeCPCleaner(ClassLoaderData* loader_data, ConstantPool* merge_cp) :
1769 _loader_data(loader_data), _cp(merge_cp), _scratch_cp(nullptr) {}
1770 ~MergeCPCleaner() {
1771 _loader_data->add_to_deallocate_list(_cp);
1772 if (_scratch_cp != nullptr) {
1773 _loader_data->add_to_deallocate_list(_scratch_cp);
1774 }
1775 }
1776 void add_scratch_cp(ConstantPool* scratch_cp) { _scratch_cp = scratch_cp; }
1777 };
1778
1779 // Merge constant pools between the_class and scratch_class and
1780 // potentially rewrite bytecodes in scratch_class to use the merged
1781 // constant pool.
1782 jvmtiError VM_RedefineClasses::merge_cp_and_rewrite(
1783 InstanceKlass* the_class, InstanceKlass* scratch_class,
1784 TRAPS) {
1785 // worst case merged constant pool length is old and new combined
1786 int merge_cp_length = the_class->constants()->length()
1787 + scratch_class->constants()->length();
1788
1789 // Constant pools are not easily reused so we allocate a new one
1790 // each time.
1791 // merge_cp is created unsafe for concurrent GC processing. It
1792 // should be marked safe before discarding it. Even though
1793 // garbage, if it crosses a card boundary, it may be scanned
1794 // in order to find the start of the first complete object on the card.
1795 ClassLoaderData* loader_data = the_class->class_loader_data();
1796 ConstantPool* merge_cp_oop =
1797 ConstantPool::allocate(loader_data,
1798 merge_cp_length,
1799 CHECK_(JVMTI_ERROR_OUT_OF_MEMORY));
1800 MergeCPCleaner cp_cleaner(loader_data, merge_cp_oop);
1801
1802 HandleMark hm(THREAD); // make sure handles are cleared before
1803 // MergeCPCleaner clears out merge_cp_oop
1804 constantPoolHandle merge_cp(THREAD, merge_cp_oop);
1805
1806 // Get constants() from the old class because it could have been rewritten
1807 // while we were at a safepoint allocating a new constant pool.
1808 constantPoolHandle old_cp(THREAD, the_class->constants());
1809 constantPoolHandle scratch_cp(THREAD, scratch_class->constants());
1810
1811 // If the length changed, the class was redefined out from under us. Return
1812 // an error.
1813 if (merge_cp_length != the_class->constants()->length()
1814 + scratch_class->constants()->length()) {
1815 return JVMTI_ERROR_INTERNAL;
1816 }
1817
1818 // Update the version number of the constant pools (may keep scratch_cp)
1819 merge_cp->increment_and_save_version(old_cp->version());
1820 scratch_cp->increment_and_save_version(old_cp->version());
1821
1822 ResourceMark rm(THREAD);
1823 _index_map_count = 0;
1824 _index_map_p = new intArray(scratch_cp->length(), scratch_cp->length(), -1);
1825
1826 _operands_cur_length = ConstantPool::operand_array_length(old_cp->operands());
1827 _operands_index_map_count = 0;
1828 int operands_index_map_len = ConstantPool::operand_array_length(scratch_cp->operands());
1829 _operands_index_map_p = new intArray(operands_index_map_len, operands_index_map_len, -1);
1830
1831 // reference to the cp holder is needed for copy_operands()
1832 merge_cp->set_pool_holder(scratch_class);
1833 bool result = merge_constant_pools(old_cp, scratch_cp, &merge_cp,
1834 &merge_cp_length, THREAD);
1835 merge_cp->set_pool_holder(nullptr);
1836
1837 if (!result) {
1838 // The merge can fail due to memory allocation failure or due
1839 // to robustness checks.
1840 return JVMTI_ERROR_INTERNAL;
1841 }
1842
1843 // Set dynamic constants attribute from the original CP.
1844 if (old_cp->has_dynamic_constant()) {
1845 scratch_cp->set_has_dynamic_constant();
1846 }
1847
1848 log_info(redefine, class, constantpool)("merge_cp_len=%d, index_map_len=%d", merge_cp_length, _index_map_count);
1849
1850 if (_index_map_count == 0) {
1851 // there is nothing to map between the new and merged constant pools
1852
1853 // Copy attributes from scratch_cp to merge_cp
1854 merge_cp->copy_fields(scratch_cp());
1855
1856 if (old_cp->length() == scratch_cp->length()) {
1857 // The old and new constant pools are the same length and the
1858 // index map is empty. This means that the three constant pools
1859 // are equivalent (but not the same). Unfortunately, the new
1860 // constant pool has not gone through link resolution nor have
1861 // the new class bytecodes gone through constant pool cache
1862 // rewriting so we can't use the old constant pool with the new
1863 // class.
1864
1865 // toss the merged constant pool at return
1866 } else if (old_cp->length() < scratch_cp->length()) {
1867 // The old constant pool has fewer entries than the new constant
1868 // pool and the index map is empty. This means the new constant
1869 // pool is a superset of the old constant pool. However, the old
1870 // class bytecodes have already gone through constant pool cache
1871 // rewriting so we can't use the new constant pool with the old
1872 // class.
1873
1874 // toss the merged constant pool at return
1875 } else {
1876 // The old constant pool has more entries than the new constant
1877 // pool and the index map is empty. This means that both the old
1878 // and merged constant pools are supersets of the new constant
1879 // pool.
1880
1881 // Replace the new constant pool with a shrunken copy of the
1882 // merged constant pool
1883 set_new_constant_pool(loader_data, scratch_class, merge_cp, merge_cp_length,
1884 CHECK_(JVMTI_ERROR_OUT_OF_MEMORY));
1885 // The new constant pool replaces scratch_cp so have cleaner clean it up.
1886 // It can't be cleaned up while there are handles to it.
1887 cp_cleaner.add_scratch_cp(scratch_cp());
1888 }
1889 } else {
1890 if (log_is_enabled(Trace, redefine, class, constantpool)) {
1891 // don't want to loop unless we are tracing
1892 int count = 0;
1893 for (int i = 1; i < _index_map_p->length(); i++) {
1894 int value = _index_map_p->at(i);
1895
1896 if (value != -1) {
1897 log_trace(redefine, class, constantpool)("index_map[%d]: old=%d new=%d", count, i, value);
1898 count++;
1899 }
1900 }
1901 }
1902
1903 // We have entries mapped between the new and merged constant pools
1904 // so we have to rewrite some constant pool references.
1905 if (!rewrite_cp_refs(scratch_class)) {
1906 return JVMTI_ERROR_INTERNAL;
1907 }
1908
1909 // Copy attributes from scratch_cp to merge_cp (should be done after rewrite_cp_refs())
1910 merge_cp->copy_fields(scratch_cp());
1911
1912 // Replace the new constant pool with a shrunken copy of the
1913 // merged constant pool so now the rewritten bytecodes have
1914 // valid references; the previous new constant pool will get
1915 // GCed.
1916 set_new_constant_pool(loader_data, scratch_class, merge_cp, merge_cp_length,
1917 CHECK_(JVMTI_ERROR_OUT_OF_MEMORY));
1918 // The new constant pool replaces scratch_cp so have cleaner clean it up.
1919 // It can't be cleaned up while there are handles to it.
1920 cp_cleaner.add_scratch_cp(scratch_cp());
1921 }
1922
1923 return JVMTI_ERROR_NONE;
1924 } // end merge_cp_and_rewrite()
1925
1926
1927 // Rewrite constant pool references in klass scratch_class.
1928 bool VM_RedefineClasses::rewrite_cp_refs(InstanceKlass* scratch_class) {
1929
1930 // rewrite constant pool references in the nest attributes:
1931 if (!rewrite_cp_refs_in_nest_attributes(scratch_class)) {
1932 // propagate failure back to caller
1933 return false;
1934 }
1935
1936 // rewrite constant pool references in the Record attribute:
1937 if (!rewrite_cp_refs_in_record_attribute(scratch_class)) {
1938 // propagate failure back to caller
1939 return false;
1940 }
1941
1942 // rewrite constant pool references in the PermittedSubclasses attribute:
1943 if (!rewrite_cp_refs_in_permitted_subclasses_attribute(scratch_class)) {
1944 // propagate failure back to caller
1945 return false;
1946 }
1947
1948 // rewrite constant pool references in the Preload attribute:
1949 if (!rewrite_cp_refs_in_preload_attribute(scratch_class)) {
1950 // propagate failure back to caller
1951 return false;
1952 }
1953
1954 // rewrite constant pool references in the methods:
1955 if (!rewrite_cp_refs_in_methods(scratch_class)) {
1956 // propagate failure back to caller
1957 return false;
1958 }
1959
1960 // rewrite constant pool references in the class_annotations:
1961 if (!rewrite_cp_refs_in_class_annotations(scratch_class)) {
1962 // propagate failure back to caller
1963 return false;
1964 }
1965
1966 // rewrite constant pool references in the fields_annotations:
1967 if (!rewrite_cp_refs_in_fields_annotations(scratch_class)) {
1968 // propagate failure back to caller
1969 return false;
1970 }
1971
1972 // rewrite constant pool references in the methods_annotations:
1973 if (!rewrite_cp_refs_in_methods_annotations(scratch_class)) {
1974 // propagate failure back to caller
1975 return false;
1976 }
1977
1978 // rewrite constant pool references in the methods_parameter_annotations:
1979 if (!rewrite_cp_refs_in_methods_parameter_annotations(scratch_class)) {
1980 // propagate failure back to caller
1981 return false;
1982 }
1983
1984 // rewrite constant pool references in the methods_default_annotations:
1985 if (!rewrite_cp_refs_in_methods_default_annotations(scratch_class)) {
1986 // propagate failure back to caller
1987 return false;
1988 }
1989
1990 // rewrite constant pool references in the class_type_annotations:
1991 if (!rewrite_cp_refs_in_class_type_annotations(scratch_class)) {
1992 // propagate failure back to caller
1993 return false;
1994 }
1995
1996 // rewrite constant pool references in the fields_type_annotations:
1997 if (!rewrite_cp_refs_in_fields_type_annotations(scratch_class)) {
1998 // propagate failure back to caller
1999 return false;
2000 }
2001
2002 // rewrite constant pool references in the methods_type_annotations:
2003 if (!rewrite_cp_refs_in_methods_type_annotations(scratch_class)) {
2004 // propagate failure back to caller
2005 return false;
2006 }
2007
2008 // There can be type annotations in the Code part of a method_info attribute.
2009 // These annotations are not accessible, even by reflection.
2010 // Currently they are not even parsed by the ClassFileParser.
2011 // If runtime access is added they will also need to be rewritten.
2012
2013 // rewrite source file name index:
2014 u2 source_file_name_idx = scratch_class->source_file_name_index();
2015 if (source_file_name_idx != 0) {
2016 u2 new_source_file_name_idx = find_new_index(source_file_name_idx);
2017 if (new_source_file_name_idx != 0) {
2018 scratch_class->set_source_file_name_index(new_source_file_name_idx);
2019 }
2020 }
2021
2022 // rewrite class generic signature index:
2023 u2 generic_signature_index = scratch_class->generic_signature_index();
2024 if (generic_signature_index != 0) {
2025 u2 new_generic_signature_index = find_new_index(generic_signature_index);
2026 if (new_generic_signature_index != 0) {
2027 scratch_class->set_generic_signature_index(new_generic_signature_index);
2028 }
2029 }
2030
2031 return true;
2032 } // end rewrite_cp_refs()
2033
2034 // Rewrite constant pool references in the NestHost and NestMembers attributes.
2035 bool VM_RedefineClasses::rewrite_cp_refs_in_nest_attributes(
2036 InstanceKlass* scratch_class) {
2037
2038 u2 cp_index = scratch_class->nest_host_index();
2039 if (cp_index != 0) {
2040 scratch_class->set_nest_host_index(find_new_index(cp_index));
2041 }
2042 Array<u2>* nest_members = scratch_class->nest_members();
2043 for (int i = 0; i < nest_members->length(); i++) {
2044 u2 cp_index = nest_members->at(i);
2045 nest_members->at_put(i, find_new_index(cp_index));
2046 }
2047 return true;
2048 }
2049
2050 // Rewrite constant pool references in the Record attribute.
2051 bool VM_RedefineClasses::rewrite_cp_refs_in_record_attribute(InstanceKlass* scratch_class) {
2052 Array<RecordComponent*>* components = scratch_class->record_components();
2053 if (components != nullptr) {
2054 for (int i = 0; i < components->length(); i++) {
2055 RecordComponent* component = components->at(i);
2056 u2 cp_index = component->name_index();
2057 component->set_name_index(find_new_index(cp_index));
2058 cp_index = component->descriptor_index();
2059 component->set_descriptor_index(find_new_index(cp_index));
2060 cp_index = component->generic_signature_index();
2061 if (cp_index != 0) {
2062 component->set_generic_signature_index(find_new_index(cp_index));
2063 }
2064
2065 AnnotationArray* annotations = component->annotations();
2066 if (annotations != nullptr && annotations->length() != 0) {
2067 int byte_i = 0; // byte index into annotations
2068 if (!rewrite_cp_refs_in_annotations_typeArray(annotations, byte_i)) {
2069 log_debug(redefine, class, annotation)("bad record_component_annotations at %d", i);
2070 // propagate failure back to caller
2071 return false;
2072 }
2073 }
2074
2075 AnnotationArray* type_annotations = component->type_annotations();
2076 if (type_annotations != nullptr && type_annotations->length() != 0) {
2077 int byte_i = 0; // byte index into annotations
2078 if (!rewrite_cp_refs_in_annotations_typeArray(type_annotations, byte_i)) {
2079 log_debug(redefine, class, annotation)("bad record_component_type_annotations at %d", i);
2080 // propagate failure back to caller
2081 return false;
2082 }
2083 }
2084 }
2085 }
2086 return true;
2087 }
2088
2089 // Rewrite constant pool references in the PermittedSubclasses attribute.
2090 bool VM_RedefineClasses::rewrite_cp_refs_in_permitted_subclasses_attribute(
2091 InstanceKlass* scratch_class) {
2092
2093 Array<u2>* permitted_subclasses = scratch_class->permitted_subclasses();
2094 assert(permitted_subclasses != nullptr, "unexpected null permitted_subclasses");
2095 for (int i = 0; i < permitted_subclasses->length(); i++) {
2096 u2 cp_index = permitted_subclasses->at(i);
2097 permitted_subclasses->at_put(i, find_new_index(cp_index));
2098 }
2099 return true;
2100 }
2101
2102 // Rewrite constant pool references in the Preload attribute.
2103 bool VM_RedefineClasses::rewrite_cp_refs_in_preload_attribute(
2104 InstanceKlass* scratch_class) {
2105
2106 Array<u2>* preload_classes = scratch_class->preload_classes();
2107 assert(preload_classes != nullptr, "unexpected null preload_classes");
2108 for (int i = 0; i < preload_classes->length(); i++) {
2109 u2 cp_index = preload_classes->at(i);
2110 preload_classes->at_put(i, find_new_index(cp_index));
2111 }
2112 return true;
2113 }
2114
2115 // Rewrite constant pool references in the methods.
2116 bool VM_RedefineClasses::rewrite_cp_refs_in_methods(InstanceKlass* scratch_class) {
2117
2118 Array<Method*>* methods = scratch_class->methods();
2119
2120 if (methods == nullptr || methods->length() == 0) {
2121 // no methods so nothing to do
2122 return true;
2123 }
2124
2125 JavaThread* THREAD = JavaThread::current(); // For exception macros.
2126 ExceptionMark em(THREAD);
2127
2128 // rewrite constant pool references in the methods:
2129 for (int i = methods->length() - 1; i >= 0; i--) {
2130 methodHandle method(THREAD, methods->at(i));
2131 methodHandle new_method;
2132 rewrite_cp_refs_in_method(method, &new_method, THREAD);
2133 if (!new_method.is_null()) {
2134 // the method has been replaced so save the new method version
2135 // even in the case of an exception. original method is on the
2136 // deallocation list.
2137 methods->at_put(i, new_method());
2138 }
2139 if (HAS_PENDING_EXCEPTION) {
2140 Symbol* ex_name = PENDING_EXCEPTION->klass()->name();
2141 log_info(redefine, class, load, exceptions)("rewrite_cp_refs_in_method exception: '%s'", ex_name->as_C_string());
2142 // Need to clear pending exception here as the super caller sets
2143 // the JVMTI_ERROR_INTERNAL if the returned value is false.
2144 CLEAR_PENDING_EXCEPTION;
2145 return false;
2146 }
2147 }
2148
2149 return true;
2150 }
2151
2152
2153 // Rewrite constant pool references in the specific method. This code
2154 // was adapted from Rewriter::rewrite_method().
2155 void VM_RedefineClasses::rewrite_cp_refs_in_method(methodHandle method,
2156 methodHandle *new_method_p, TRAPS) {
2157
2158 *new_method_p = methodHandle(); // default is no new method
2159
2160 // We cache a pointer to the bytecodes here in code_base. If GC
2161 // moves the Method*, then the bytecodes will also move which
2162 // will likely cause a crash. We create a NoSafepointVerifier
2163 // object to detect whether we pass a possible safepoint in this
2164 // code block.
2165 NoSafepointVerifier nsv;
2166
2167 // Bytecodes and their length
2168 address code_base = method->code_base();
2169 int code_length = method->code_size();
2170
2171 int bc_length;
2172 for (int bci = 0; bci < code_length; bci += bc_length) {
2173 address bcp = code_base + bci;
2174 Bytecodes::Code c = (Bytecodes::Code)(*bcp);
2175
2176 bc_length = Bytecodes::length_for(c);
2177 if (bc_length == 0) {
2178 // More complicated bytecodes report a length of zero so
2179 // we have to try again a slightly different way.
2180 bc_length = Bytecodes::length_at(method(), bcp);
2181 }
2182
2183 assert(bc_length != 0, "impossible bytecode length");
2184
2185 switch (c) {
2186 case Bytecodes::_ldc:
2187 {
2188 u1 cp_index = *(bcp + 1);
2189 u2 new_index = find_new_index(cp_index);
2190
2191 if (StressLdcRewrite && new_index == 0) {
2192 // If we are stressing ldc -> ldc_w rewriting, then we
2193 // always need a new_index value.
2194 new_index = cp_index;
2195 }
2196 if (new_index != 0) {
2197 // the original index is mapped so we have more work to do
2198 if (!StressLdcRewrite && new_index <= max_jubyte) {
2199 // The new value can still use ldc instead of ldc_w
2200 // unless we are trying to stress ldc -> ldc_w rewriting
2201 log_trace(redefine, class, constantpool)
2202 ("%s@" INTPTR_FORMAT " old=%d, new=%d", Bytecodes::name(c), p2i(bcp), cp_index, new_index);
2203 // We checked that new_index fits in a u1 so this cast is safe
2204 *(bcp + 1) = (u1)new_index;
2205 } else {
2206 log_trace(redefine, class, constantpool)
2207 ("%s->ldc_w@" INTPTR_FORMAT " old=%d, new=%d", Bytecodes::name(c), p2i(bcp), cp_index, new_index);
2208 // the new value needs ldc_w instead of ldc
2209 u_char inst_buffer[4]; // max instruction size is 4 bytes
2210 bcp = (address)inst_buffer;
2211 // construct new instruction sequence
2212 *bcp = Bytecodes::_ldc_w;
2213 bcp++;
2214 // Rewriter::rewrite_method() does not rewrite ldc -> ldc_w.
2215 // See comment below for difference between put_Java_u2()
2216 // and put_native_u2().
2217 Bytes::put_Java_u2(bcp, new_index);
2218
2219 Relocator rc(method, nullptr /* no RelocatorListener needed */);
2220 methodHandle m;
2221 {
2222 PauseNoSafepointVerifier pnsv(&nsv);
2223
2224 // ldc is 2 bytes and ldc_w is 3 bytes
2225 m = rc.insert_space_at(bci, 3, inst_buffer, CHECK);
2226 }
2227
2228 // return the new method so that the caller can update
2229 // the containing class
2230 *new_method_p = method = m;
2231 // switch our bytecode processing loop from the old method
2232 // to the new method
2233 code_base = method->code_base();
2234 code_length = method->code_size();
2235 bcp = code_base + bci;
2236 c = (Bytecodes::Code)(*bcp);
2237 bc_length = Bytecodes::length_for(c);
2238 assert(bc_length != 0, "sanity check");
2239 } // end we need ldc_w instead of ldc
2240 } // end if there is a mapped index
2241 } break;
2242
2243 // these bytecodes have a two-byte constant pool index
2244 case Bytecodes::_anewarray : // fall through
2245 case Bytecodes::_checkcast : // fall through
2246 case Bytecodes::_getfield : // fall through
2247 case Bytecodes::_getstatic : // fall through
2248 case Bytecodes::_instanceof : // fall through
2249 case Bytecodes::_invokedynamic : // fall through
2250 case Bytecodes::_invokeinterface: // fall through
2251 case Bytecodes::_invokespecial : // fall through
2252 case Bytecodes::_invokestatic : // fall through
2253 case Bytecodes::_invokevirtual : // fall through
2254 case Bytecodes::_ldc_w : // fall through
2255 case Bytecodes::_ldc2_w : // fall through
2256 case Bytecodes::_multianewarray : // fall through
2257 case Bytecodes::_new : // fall through
2258 case Bytecodes::_putfield : // fall through
2259 case Bytecodes::_putstatic :
2260 {
2261 address p = bcp + 1;
2262 int cp_index = Bytes::get_Java_u2(p);
2263 u2 new_index = find_new_index(cp_index);
2264 if (new_index != 0) {
2265 // the original index is mapped so update w/ new value
2266 log_trace(redefine, class, constantpool)
2267 ("%s@" INTPTR_FORMAT " old=%d, new=%d", Bytecodes::name(c),p2i(bcp), cp_index, new_index);
2268 // Rewriter::rewrite_method() uses put_native_u2() in this
2269 // situation because it is reusing the constant pool index
2270 // location for a native index into the ConstantPoolCache.
2271 // Since we are updating the constant pool index prior to
2272 // verification and ConstantPoolCache initialization, we
2273 // need to keep the new index in Java byte order.
2274 Bytes::put_Java_u2(p, new_index);
2275 }
2276 } break;
2277 default:
2278 break;
2279 }
2280 } // end for each bytecode
2281 } // end rewrite_cp_refs_in_method()
2282
2283
2284 // Rewrite constant pool references in the class_annotations field.
2285 bool VM_RedefineClasses::rewrite_cp_refs_in_class_annotations(InstanceKlass* scratch_class) {
2286
2287 AnnotationArray* class_annotations = scratch_class->class_annotations();
2288 if (class_annotations == nullptr || class_annotations->length() == 0) {
2289 // no class_annotations so nothing to do
2290 return true;
2291 }
2292
2293 log_debug(redefine, class, annotation)("class_annotations length=%d", class_annotations->length());
2294
2295 int byte_i = 0; // byte index into class_annotations
2296 return rewrite_cp_refs_in_annotations_typeArray(class_annotations, byte_i);
2297 }
2298
2299
2300 // Rewrite constant pool references in an annotations typeArray. This
2301 // "structure" is adapted from the RuntimeVisibleAnnotations_attribute
2302 // that is described in section 4.8.15 of the 2nd-edition of the VM spec:
2303 //
2304 // annotations_typeArray {
2305 // u2 num_annotations;
2306 // annotation annotations[num_annotations];
2307 // }
2308 //
2309 bool VM_RedefineClasses::rewrite_cp_refs_in_annotations_typeArray(
2310 AnnotationArray* annotations_typeArray, int &byte_i_ref) {
2311
2312 if ((byte_i_ref + 2) > annotations_typeArray->length()) {
2313 // not enough room for num_annotations field
2314 log_debug(redefine, class, annotation)("length() is too small for num_annotations field");
2315 return false;
2316 }
2317
2318 u2 num_annotations = Bytes::get_Java_u2((address)
2319 annotations_typeArray->adr_at(byte_i_ref));
2320 byte_i_ref += 2;
2321
2322 log_debug(redefine, class, annotation)("num_annotations=%d", num_annotations);
2323
2324 int calc_num_annotations = 0;
2325 for (; calc_num_annotations < num_annotations; calc_num_annotations++) {
2326 if (!rewrite_cp_refs_in_annotation_struct(annotations_typeArray, byte_i_ref)) {
2327 log_debug(redefine, class, annotation)("bad annotation_struct at %d", calc_num_annotations);
2328 // propagate failure back to caller
2329 return false;
2330 }
2331 }
2332 assert(num_annotations == calc_num_annotations, "sanity check");
2333
2334 return true;
2335 } // end rewrite_cp_refs_in_annotations_typeArray()
2336
2337
2338 // Rewrite constant pool references in the annotation struct portion of
2339 // an annotations_typeArray. This "structure" is from section 4.8.15 of
2340 // the 2nd-edition of the VM spec:
2341 //
2342 // struct annotation {
2343 // u2 type_index;
2344 // u2 num_element_value_pairs;
2345 // {
2346 // u2 element_name_index;
2347 // element_value value;
2348 // } element_value_pairs[num_element_value_pairs];
2349 // }
2350 //
2351 bool VM_RedefineClasses::rewrite_cp_refs_in_annotation_struct(
2352 AnnotationArray* annotations_typeArray, int &byte_i_ref) {
2353 if ((byte_i_ref + 2 + 2) > annotations_typeArray->length()) {
2354 // not enough room for smallest annotation_struct
2355 log_debug(redefine, class, annotation)("length() is too small for annotation_struct");
2356 return false;
2357 }
2358
2359 u2 type_index = rewrite_cp_ref_in_annotation_data(annotations_typeArray,
2360 byte_i_ref, "type_index");
2361
2362 u2 num_element_value_pairs = Bytes::get_Java_u2((address)
2363 annotations_typeArray->adr_at(byte_i_ref));
2364 byte_i_ref += 2;
2365
2366 log_debug(redefine, class, annotation)
2367 ("type_index=%d num_element_value_pairs=%d", type_index, num_element_value_pairs);
2368
2369 int calc_num_element_value_pairs = 0;
2370 for (; calc_num_element_value_pairs < num_element_value_pairs;
2371 calc_num_element_value_pairs++) {
2372 if ((byte_i_ref + 2) > annotations_typeArray->length()) {
2373 // not enough room for another element_name_index, let alone
2374 // the rest of another component
2375 log_debug(redefine, class, annotation)("length() is too small for element_name_index");
2376 return false;
2377 }
2378
2379 u2 element_name_index = rewrite_cp_ref_in_annotation_data(
2380 annotations_typeArray, byte_i_ref,
2381 "element_name_index");
2382
2383 log_debug(redefine, class, annotation)("element_name_index=%d", element_name_index);
2384
2385 if (!rewrite_cp_refs_in_element_value(annotations_typeArray, byte_i_ref)) {
2386 log_debug(redefine, class, annotation)("bad element_value at %d", calc_num_element_value_pairs);
2387 // propagate failure back to caller
2388 return false;
2389 }
2390 } // end for each component
2391 assert(num_element_value_pairs == calc_num_element_value_pairs,
2392 "sanity check");
2393
2394 return true;
2395 } // end rewrite_cp_refs_in_annotation_struct()
2396
2397
2398 // Rewrite a constant pool reference at the current position in
2399 // annotations_typeArray if needed. Returns the original constant
2400 // pool reference if a rewrite was not needed or the new constant
2401 // pool reference if a rewrite was needed.
2402 u2 VM_RedefineClasses::rewrite_cp_ref_in_annotation_data(
2403 AnnotationArray* annotations_typeArray, int &byte_i_ref,
2404 const char * trace_mesg) {
2405
2406 address cp_index_addr = (address)
2407 annotations_typeArray->adr_at(byte_i_ref);
2408 u2 old_cp_index = Bytes::get_Java_u2(cp_index_addr);
2409 u2 new_cp_index = find_new_index(old_cp_index);
2410 if (new_cp_index != 0) {
2411 log_debug(redefine, class, annotation)("mapped old %s=%d", trace_mesg, old_cp_index);
2412 Bytes::put_Java_u2(cp_index_addr, new_cp_index);
2413 old_cp_index = new_cp_index;
2414 }
2415 byte_i_ref += 2;
2416 return old_cp_index;
2417 }
2418
2419
2420 // Rewrite constant pool references in the element_value portion of an
2421 // annotations_typeArray. This "structure" is from section 4.8.15.1 of
2422 // the 2nd-edition of the VM spec:
2423 //
2424 // struct element_value {
2425 // u1 tag;
2426 // union {
2427 // u2 const_value_index;
2428 // {
2429 // u2 type_name_index;
2430 // u2 const_name_index;
2431 // } enum_const_value;
2432 // u2 class_info_index;
2433 // annotation annotation_value;
2434 // struct {
2435 // u2 num_values;
2436 // element_value values[num_values];
2437 // } array_value;
2438 // } value;
2439 // }
2440 //
2441 bool VM_RedefineClasses::rewrite_cp_refs_in_element_value(
2442 AnnotationArray* annotations_typeArray, int &byte_i_ref) {
2443
2444 if ((byte_i_ref + 1) > annotations_typeArray->length()) {
2445 // not enough room for a tag let alone the rest of an element_value
2446 log_debug(redefine, class, annotation)("length() is too small for a tag");
2447 return false;
2448 }
2449
2450 u1 tag = annotations_typeArray->at(byte_i_ref);
2451 byte_i_ref++;
2452 log_debug(redefine, class, annotation)("tag='%c'", tag);
2453
2454 switch (tag) {
2455 // These BaseType tag values are from Table 4.2 in VM spec:
2456 case JVM_SIGNATURE_BYTE:
2457 case JVM_SIGNATURE_CHAR:
2458 case JVM_SIGNATURE_DOUBLE:
2459 case JVM_SIGNATURE_FLOAT:
2460 case JVM_SIGNATURE_INT:
2461 case JVM_SIGNATURE_LONG:
2462 case JVM_SIGNATURE_SHORT:
2463 case JVM_SIGNATURE_BOOLEAN:
2464
2465 // The remaining tag values are from Table 4.8 in the 2nd-edition of
2466 // the VM spec:
2467 case 's':
2468 {
2469 // For the above tag values (including the BaseType values),
2470 // value.const_value_index is right union field.
2471
2472 if ((byte_i_ref + 2) > annotations_typeArray->length()) {
2473 // not enough room for a const_value_index
2474 log_debug(redefine, class, annotation)("length() is too small for a const_value_index");
2475 return false;
2476 }
2477
2478 u2 const_value_index = rewrite_cp_ref_in_annotation_data(
2479 annotations_typeArray, byte_i_ref,
2480 "const_value_index");
2481
2482 log_debug(redefine, class, annotation)("const_value_index=%d", const_value_index);
2483 } break;
2484
2485 case 'e':
2486 {
2487 // for the above tag value, value.enum_const_value is right union field
2488
2489 if ((byte_i_ref + 4) > annotations_typeArray->length()) {
2490 // not enough room for a enum_const_value
2491 log_debug(redefine, class, annotation)("length() is too small for a enum_const_value");
2492 return false;
2493 }
2494
2495 u2 type_name_index = rewrite_cp_ref_in_annotation_data(
2496 annotations_typeArray, byte_i_ref,
2497 "type_name_index");
2498
2499 u2 const_name_index = rewrite_cp_ref_in_annotation_data(
2500 annotations_typeArray, byte_i_ref,
2501 "const_name_index");
2502
2503 log_debug(redefine, class, annotation)
2504 ("type_name_index=%d const_name_index=%d", type_name_index, const_name_index);
2505 } break;
2506
2507 case 'c':
2508 {
2509 // for the above tag value, value.class_info_index is right union field
2510
2511 if ((byte_i_ref + 2) > annotations_typeArray->length()) {
2512 // not enough room for a class_info_index
2513 log_debug(redefine, class, annotation)("length() is too small for a class_info_index");
2514 return false;
2515 }
2516
2517 u2 class_info_index = rewrite_cp_ref_in_annotation_data(
2518 annotations_typeArray, byte_i_ref,
2519 "class_info_index");
2520
2521 log_debug(redefine, class, annotation)("class_info_index=%d", class_info_index);
2522 } break;
2523
2524 case '@':
2525 // For the above tag value, value.attr_value is the right union
2526 // field. This is a nested annotation.
2527 if (!rewrite_cp_refs_in_annotation_struct(annotations_typeArray, byte_i_ref)) {
2528 // propagate failure back to caller
2529 return false;
2530 }
2531 break;
2532
2533 case JVM_SIGNATURE_ARRAY:
2534 {
2535 if ((byte_i_ref + 2) > annotations_typeArray->length()) {
2536 // not enough room for a num_values field
2537 log_debug(redefine, class, annotation)("length() is too small for a num_values field");
2538 return false;
2539 }
2540
2541 // For the above tag value, value.array_value is the right union
2542 // field. This is an array of nested element_value.
2543 u2 num_values = Bytes::get_Java_u2((address)
2544 annotations_typeArray->adr_at(byte_i_ref));
2545 byte_i_ref += 2;
2546 log_debug(redefine, class, annotation)("num_values=%d", num_values);
2547
2548 int calc_num_values = 0;
2549 for (; calc_num_values < num_values; calc_num_values++) {
2550 if (!rewrite_cp_refs_in_element_value(annotations_typeArray, byte_i_ref)) {
2551 log_debug(redefine, class, annotation)("bad nested element_value at %d", calc_num_values);
2552 // propagate failure back to caller
2553 return false;
2554 }
2555 }
2556 assert(num_values == calc_num_values, "sanity check");
2557 } break;
2558
2559 default:
2560 log_debug(redefine, class, annotation)("bad tag=0x%x", tag);
2561 return false;
2562 } // end decode tag field
2563
2564 return true;
2565 } // end rewrite_cp_refs_in_element_value()
2566
2567
2568 // Rewrite constant pool references in a fields_annotations field.
2569 bool VM_RedefineClasses::rewrite_cp_refs_in_fields_annotations(
2570 InstanceKlass* scratch_class) {
2571
2572 Array<AnnotationArray*>* fields_annotations = scratch_class->fields_annotations();
2573
2574 if (fields_annotations == nullptr || fields_annotations->length() == 0) {
2575 // no fields_annotations so nothing to do
2576 return true;
2577 }
2578
2579 log_debug(redefine, class, annotation)("fields_annotations length=%d", fields_annotations->length());
2580
2581 for (int i = 0; i < fields_annotations->length(); i++) {
2582 AnnotationArray* field_annotations = fields_annotations->at(i);
2583 if (field_annotations == nullptr || field_annotations->length() == 0) {
2584 // this field does not have any annotations so skip it
2585 continue;
2586 }
2587
2588 int byte_i = 0; // byte index into field_annotations
2589 if (!rewrite_cp_refs_in_annotations_typeArray(field_annotations, byte_i)) {
2590 log_debug(redefine, class, annotation)("bad field_annotations at %d", i);
2591 // propagate failure back to caller
2592 return false;
2593 }
2594 }
2595
2596 return true;
2597 } // end rewrite_cp_refs_in_fields_annotations()
2598
2599
2600 // Rewrite constant pool references in a methods_annotations field.
2601 bool VM_RedefineClasses::rewrite_cp_refs_in_methods_annotations(
2602 InstanceKlass* scratch_class) {
2603
2604 for (int i = 0; i < scratch_class->methods()->length(); i++) {
2605 Method* m = scratch_class->methods()->at(i);
2606 AnnotationArray* method_annotations = m->constMethod()->method_annotations();
2607
2608 if (method_annotations == nullptr || method_annotations->length() == 0) {
2609 // this method does not have any annotations so skip it
2610 continue;
2611 }
2612
2613 int byte_i = 0; // byte index into method_annotations
2614 if (!rewrite_cp_refs_in_annotations_typeArray(method_annotations, byte_i)) {
2615 log_debug(redefine, class, annotation)("bad method_annotations at %d", i);
2616 // propagate failure back to caller
2617 return false;
2618 }
2619 }
2620
2621 return true;
2622 } // end rewrite_cp_refs_in_methods_annotations()
2623
2624
2625 // Rewrite constant pool references in a methods_parameter_annotations
2626 // field. This "structure" is adapted from the
2627 // RuntimeVisibleParameterAnnotations_attribute described in section
2628 // 4.8.17 of the 2nd-edition of the VM spec:
2629 //
2630 // methods_parameter_annotations_typeArray {
2631 // u1 num_parameters;
2632 // {
2633 // u2 num_annotations;
2634 // annotation annotations[num_annotations];
2635 // } parameter_annotations[num_parameters];
2636 // }
2637 //
2638 bool VM_RedefineClasses::rewrite_cp_refs_in_methods_parameter_annotations(
2639 InstanceKlass* scratch_class) {
2640
2641 for (int i = 0; i < scratch_class->methods()->length(); i++) {
2642 Method* m = scratch_class->methods()->at(i);
2643 AnnotationArray* method_parameter_annotations = m->constMethod()->parameter_annotations();
2644 if (method_parameter_annotations == nullptr
2645 || method_parameter_annotations->length() == 0) {
2646 // this method does not have any parameter annotations so skip it
2647 continue;
2648 }
2649
2650 if (method_parameter_annotations->length() < 1) {
2651 // not enough room for a num_parameters field
2652 log_debug(redefine, class, annotation)("length() is too small for a num_parameters field at %d", i);
2653 return false;
2654 }
2655
2656 int byte_i = 0; // byte index into method_parameter_annotations
2657
2658 u1 num_parameters = method_parameter_annotations->at(byte_i);
2659 byte_i++;
2660
2661 log_debug(redefine, class, annotation)("num_parameters=%d", num_parameters);
2662
2663 int calc_num_parameters = 0;
2664 for (; calc_num_parameters < num_parameters; calc_num_parameters++) {
2665 if (!rewrite_cp_refs_in_annotations_typeArray(method_parameter_annotations, byte_i)) {
2666 log_debug(redefine, class, annotation)("bad method_parameter_annotations at %d", calc_num_parameters);
2667 // propagate failure back to caller
2668 return false;
2669 }
2670 }
2671 assert(num_parameters == calc_num_parameters, "sanity check");
2672 }
2673
2674 return true;
2675 } // end rewrite_cp_refs_in_methods_parameter_annotations()
2676
2677
2678 // Rewrite constant pool references in a methods_default_annotations
2679 // field. This "structure" is adapted from the AnnotationDefault_attribute
2680 // that is described in section 4.8.19 of the 2nd-edition of the VM spec:
2681 //
2682 // methods_default_annotations_typeArray {
2683 // element_value default_value;
2684 // }
2685 //
2686 bool VM_RedefineClasses::rewrite_cp_refs_in_methods_default_annotations(
2687 InstanceKlass* scratch_class) {
2688
2689 for (int i = 0; i < scratch_class->methods()->length(); i++) {
2690 Method* m = scratch_class->methods()->at(i);
2691 AnnotationArray* method_default_annotations = m->constMethod()->default_annotations();
2692 if (method_default_annotations == nullptr
2693 || method_default_annotations->length() == 0) {
2694 // this method does not have any default annotations so skip it
2695 continue;
2696 }
2697
2698 int byte_i = 0; // byte index into method_default_annotations
2699
2700 if (!rewrite_cp_refs_in_element_value(
2701 method_default_annotations, byte_i)) {
2702 log_debug(redefine, class, annotation)("bad default element_value at %d", i);
2703 // propagate failure back to caller
2704 return false;
2705 }
2706 }
2707
2708 return true;
2709 } // end rewrite_cp_refs_in_methods_default_annotations()
2710
2711
2712 // Rewrite constant pool references in a class_type_annotations field.
2713 bool VM_RedefineClasses::rewrite_cp_refs_in_class_type_annotations(
2714 InstanceKlass* scratch_class) {
2715
2716 AnnotationArray* class_type_annotations = scratch_class->class_type_annotations();
2717 if (class_type_annotations == nullptr || class_type_annotations->length() == 0) {
2718 // no class_type_annotations so nothing to do
2719 return true;
2720 }
2721
2722 log_debug(redefine, class, annotation)("class_type_annotations length=%d", class_type_annotations->length());
2723
2724 int byte_i = 0; // byte index into class_type_annotations
2725 return rewrite_cp_refs_in_type_annotations_typeArray(class_type_annotations,
2726 byte_i, "ClassFile");
2727 } // end rewrite_cp_refs_in_class_type_annotations()
2728
2729
2730 // Rewrite constant pool references in a fields_type_annotations field.
2731 bool VM_RedefineClasses::rewrite_cp_refs_in_fields_type_annotations(InstanceKlass* scratch_class) {
2732
2733 Array<AnnotationArray*>* fields_type_annotations = scratch_class->fields_type_annotations();
2734 if (fields_type_annotations == nullptr || fields_type_annotations->length() == 0) {
2735 // no fields_type_annotations so nothing to do
2736 return true;
2737 }
2738
2739 log_debug(redefine, class, annotation)("fields_type_annotations length=%d", fields_type_annotations->length());
2740
2741 for (int i = 0; i < fields_type_annotations->length(); i++) {
2742 AnnotationArray* field_type_annotations = fields_type_annotations->at(i);
2743 if (field_type_annotations == nullptr || field_type_annotations->length() == 0) {
2744 // this field does not have any annotations so skip it
2745 continue;
2746 }
2747
2748 int byte_i = 0; // byte index into field_type_annotations
2749 if (!rewrite_cp_refs_in_type_annotations_typeArray(field_type_annotations,
2750 byte_i, "field_info")) {
2751 log_debug(redefine, class, annotation)("bad field_type_annotations at %d", i);
2752 // propagate failure back to caller
2753 return false;
2754 }
2755 }
2756
2757 return true;
2758 } // end rewrite_cp_refs_in_fields_type_annotations()
2759
2760
2761 // Rewrite constant pool references in a methods_type_annotations field.
2762 bool VM_RedefineClasses::rewrite_cp_refs_in_methods_type_annotations(
2763 InstanceKlass* scratch_class) {
2764
2765 for (int i = 0; i < scratch_class->methods()->length(); i++) {
2766 Method* m = scratch_class->methods()->at(i);
2767 AnnotationArray* method_type_annotations = m->constMethod()->type_annotations();
2768
2769 if (method_type_annotations == nullptr || method_type_annotations->length() == 0) {
2770 // this method does not have any annotations so skip it
2771 continue;
2772 }
2773
2774 log_debug(redefine, class, annotation)("methods type_annotations length=%d", method_type_annotations->length());
2775
2776 int byte_i = 0; // byte index into method_type_annotations
2777 if (!rewrite_cp_refs_in_type_annotations_typeArray(method_type_annotations,
2778 byte_i, "method_info")) {
2779 log_debug(redefine, class, annotation)("bad method_type_annotations at %d", i);
2780 // propagate failure back to caller
2781 return false;
2782 }
2783 }
2784
2785 return true;
2786 } // end rewrite_cp_refs_in_methods_type_annotations()
2787
2788
2789 // Rewrite constant pool references in a type_annotations
2790 // field. This "structure" is adapted from the
2791 // RuntimeVisibleTypeAnnotations_attribute described in
2792 // section 4.7.20 of the Java SE 8 Edition of the VM spec:
2793 //
2794 // type_annotations_typeArray {
2795 // u2 num_annotations;
2796 // type_annotation annotations[num_annotations];
2797 // }
2798 //
2799 bool VM_RedefineClasses::rewrite_cp_refs_in_type_annotations_typeArray(
2800 AnnotationArray* type_annotations_typeArray, int &byte_i_ref,
2801 const char * location_mesg) {
2802
2803 if ((byte_i_ref + 2) > type_annotations_typeArray->length()) {
2804 // not enough room for num_annotations field
2805 log_debug(redefine, class, annotation)("length() is too small for num_annotations field");
2806 return false;
2807 }
2808
2809 u2 num_annotations = Bytes::get_Java_u2((address)
2810 type_annotations_typeArray->adr_at(byte_i_ref));
2811 byte_i_ref += 2;
2812
2813 log_debug(redefine, class, annotation)("num_type_annotations=%d", num_annotations);
2814
2815 int calc_num_annotations = 0;
2816 for (; calc_num_annotations < num_annotations; calc_num_annotations++) {
2817 if (!rewrite_cp_refs_in_type_annotation_struct(type_annotations_typeArray,
2818 byte_i_ref, location_mesg)) {
2819 log_debug(redefine, class, annotation)("bad type_annotation_struct at %d", calc_num_annotations);
2820 // propagate failure back to caller
2821 return false;
2822 }
2823 }
2824 assert(num_annotations == calc_num_annotations, "sanity check");
2825
2826 if (byte_i_ref != type_annotations_typeArray->length()) {
2827 log_debug(redefine, class, annotation)
2828 ("read wrong amount of bytes at end of processing type_annotations_typeArray (%d of %d bytes were read)",
2829 byte_i_ref, type_annotations_typeArray->length());
2830 return false;
2831 }
2832
2833 return true;
2834 } // end rewrite_cp_refs_in_type_annotations_typeArray()
2835
2836
2837 // Rewrite constant pool references in a type_annotation
2838 // field. This "structure" is adapted from the
2839 // RuntimeVisibleTypeAnnotations_attribute described in
2840 // section 4.7.20 of the Java SE 8 Edition of the VM spec:
2841 //
2842 // type_annotation {
2843 // u1 target_type;
2844 // union {
2845 // type_parameter_target;
2846 // supertype_target;
2847 // type_parameter_bound_target;
2848 // empty_target;
2849 // method_formal_parameter_target;
2850 // throws_target;
2851 // localvar_target;
2852 // catch_target;
2853 // offset_target;
2854 // type_argument_target;
2855 // } target_info;
2856 // type_path target_path;
2857 // annotation anno;
2858 // }
2859 //
2860 bool VM_RedefineClasses::rewrite_cp_refs_in_type_annotation_struct(
2861 AnnotationArray* type_annotations_typeArray, int &byte_i_ref,
2862 const char * location_mesg) {
2863
2864 if (!skip_type_annotation_target(type_annotations_typeArray,
2865 byte_i_ref, location_mesg)) {
2866 return false;
2867 }
2868
2869 if (!skip_type_annotation_type_path(type_annotations_typeArray, byte_i_ref)) {
2870 return false;
2871 }
2872
2873 if (!rewrite_cp_refs_in_annotation_struct(type_annotations_typeArray, byte_i_ref)) {
2874 return false;
2875 }
2876
2877 return true;
2878 } // end rewrite_cp_refs_in_type_annotation_struct()
2879
2880
2881 // Read, verify and skip over the target_type and target_info part
2882 // so that rewriting can continue in the later parts of the struct.
2883 //
2884 // u1 target_type;
2885 // union {
2886 // type_parameter_target;
2887 // supertype_target;
2888 // type_parameter_bound_target;
2889 // empty_target;
2890 // method_formal_parameter_target;
2891 // throws_target;
2892 // localvar_target;
2893 // catch_target;
2894 // offset_target;
2895 // type_argument_target;
2896 // } target_info;
2897 //
2898 bool VM_RedefineClasses::skip_type_annotation_target(
2899 AnnotationArray* type_annotations_typeArray, int &byte_i_ref,
2900 const char * location_mesg) {
2901
2902 if ((byte_i_ref + 1) > type_annotations_typeArray->length()) {
2903 // not enough room for a target_type let alone the rest of a type_annotation
2904 log_debug(redefine, class, annotation)("length() is too small for a target_type");
2905 return false;
2906 }
2907
2908 u1 target_type = type_annotations_typeArray->at(byte_i_ref);
2909 byte_i_ref += 1;
2910 log_debug(redefine, class, annotation)("target_type=0x%.2x", target_type);
2911 log_debug(redefine, class, annotation)("location=%s", location_mesg);
2912
2913 // Skip over target_info
2914 switch (target_type) {
2915 case 0x00:
2916 // kind: type parameter declaration of generic class or interface
2917 // location: ClassFile
2918 case 0x01:
2919 // kind: type parameter declaration of generic method or constructor
2920 // location: method_info
2921
2922 {
2923 // struct:
2924 // type_parameter_target {
2925 // u1 type_parameter_index;
2926 // }
2927 //
2928 if ((byte_i_ref + 1) > type_annotations_typeArray->length()) {
2929 log_debug(redefine, class, annotation)("length() is too small for a type_parameter_target");
2930 return false;
2931 }
2932
2933 u1 type_parameter_index = type_annotations_typeArray->at(byte_i_ref);
2934 byte_i_ref += 1;
2935
2936 log_debug(redefine, class, annotation)("type_parameter_target: type_parameter_index=%d", type_parameter_index);
2937 } break;
2938
2939 case 0x10:
2940 // kind: type in extends clause of class or interface declaration
2941 // or in implements clause of interface declaration
2942 // location: ClassFile
2943
2944 {
2945 // struct:
2946 // supertype_target {
2947 // u2 supertype_index;
2948 // }
2949 //
2950 if ((byte_i_ref + 2) > type_annotations_typeArray->length()) {
2951 log_debug(redefine, class, annotation)("length() is too small for a supertype_target");
2952 return false;
2953 }
2954
2955 u2 supertype_index = Bytes::get_Java_u2((address)
2956 type_annotations_typeArray->adr_at(byte_i_ref));
2957 byte_i_ref += 2;
2958
2959 log_debug(redefine, class, annotation)("supertype_target: supertype_index=%d", supertype_index);
2960 } break;
2961
2962 case 0x11:
2963 // kind: type in bound of type parameter declaration of generic class or interface
2964 // location: ClassFile
2965 case 0x12:
2966 // kind: type in bound of type parameter declaration of generic method or constructor
2967 // location: method_info
2968
2969 {
2970 // struct:
2971 // type_parameter_bound_target {
2972 // u1 type_parameter_index;
2973 // u1 bound_index;
2974 // }
2975 //
2976 if ((byte_i_ref + 2) > type_annotations_typeArray->length()) {
2977 log_debug(redefine, class, annotation)("length() is too small for a type_parameter_bound_target");
2978 return false;
2979 }
2980
2981 u1 type_parameter_index = type_annotations_typeArray->at(byte_i_ref);
2982 byte_i_ref += 1;
2983 u1 bound_index = type_annotations_typeArray->at(byte_i_ref);
2984 byte_i_ref += 1;
2985
2986 log_debug(redefine, class, annotation)
2987 ("type_parameter_bound_target: type_parameter_index=%d, bound_index=%d", type_parameter_index, bound_index);
2988 } break;
2989
2990 case 0x13:
2991 // kind: type in field declaration
2992 // location: field_info
2993 case 0x14:
2994 // kind: return type of method, or type of newly constructed object
2995 // location: method_info
2996 case 0x15:
2997 // kind: receiver type of method or constructor
2998 // location: method_info
2999
3000 {
3001 // struct:
3002 // empty_target {
3003 // }
3004 //
3005 log_debug(redefine, class, annotation)("empty_target");
3006 } break;
3007
3008 case 0x16:
3009 // kind: type in formal parameter declaration of method, constructor, or lambda expression
3010 // location: method_info
3011
3012 {
3013 // struct:
3014 // formal_parameter_target {
3015 // u1 formal_parameter_index;
3016 // }
3017 //
3018 if ((byte_i_ref + 1) > type_annotations_typeArray->length()) {
3019 log_debug(redefine, class, annotation)("length() is too small for a formal_parameter_target");
3020 return false;
3021 }
3022
3023 u1 formal_parameter_index = type_annotations_typeArray->at(byte_i_ref);
3024 byte_i_ref += 1;
3025
3026 log_debug(redefine, class, annotation)
3027 ("formal_parameter_target: formal_parameter_index=%d", formal_parameter_index);
3028 } break;
3029
3030 case 0x17:
3031 // kind: type in throws clause of method or constructor
3032 // location: method_info
3033
3034 {
3035 // struct:
3036 // throws_target {
3037 // u2 throws_type_index
3038 // }
3039 //
3040 if ((byte_i_ref + 2) > type_annotations_typeArray->length()) {
3041 log_debug(redefine, class, annotation)("length() is too small for a throws_target");
3042 return false;
3043 }
3044
3045 u2 throws_type_index = Bytes::get_Java_u2((address)
3046 type_annotations_typeArray->adr_at(byte_i_ref));
3047 byte_i_ref += 2;
3048
3049 log_debug(redefine, class, annotation)("throws_target: throws_type_index=%d", throws_type_index);
3050 } break;
3051
3052 case 0x40:
3053 // kind: type in local variable declaration
3054 // location: Code
3055 case 0x41:
3056 // kind: type in resource variable declaration
3057 // location: Code
3058
3059 {
3060 // struct:
3061 // localvar_target {
3062 // u2 table_length;
3063 // struct {
3064 // u2 start_pc;
3065 // u2 length;
3066 // u2 index;
3067 // } table[table_length];
3068 // }
3069 //
3070 if ((byte_i_ref + 2) > type_annotations_typeArray->length()) {
3071 // not enough room for a table_length let alone the rest of a localvar_target
3072 log_debug(redefine, class, annotation)("length() is too small for a localvar_target table_length");
3073 return false;
3074 }
3075
3076 u2 table_length = Bytes::get_Java_u2((address)
3077 type_annotations_typeArray->adr_at(byte_i_ref));
3078 byte_i_ref += 2;
3079
3080 log_debug(redefine, class, annotation)("localvar_target: table_length=%d", table_length);
3081
3082 int table_struct_size = 2 + 2 + 2; // 3 u2 variables per table entry
3083 int table_size = table_length * table_struct_size;
3084
3085 if ((byte_i_ref + table_size) > type_annotations_typeArray->length()) {
3086 // not enough room for a table
3087 log_debug(redefine, class, annotation)("length() is too small for a table array of length %d", table_length);
3088 return false;
3089 }
3090
3091 // Skip over table
3092 byte_i_ref += table_size;
3093 } break;
3094
3095 case 0x42:
3096 // kind: type in exception parameter declaration
3097 // location: Code
3098
3099 {
3100 // struct:
3101 // catch_target {
3102 // u2 exception_table_index;
3103 // }
3104 //
3105 if ((byte_i_ref + 2) > type_annotations_typeArray->length()) {
3106 log_debug(redefine, class, annotation)("length() is too small for a catch_target");
3107 return false;
3108 }
3109
3110 u2 exception_table_index = Bytes::get_Java_u2((address)
3111 type_annotations_typeArray->adr_at(byte_i_ref));
3112 byte_i_ref += 2;
3113
3114 log_debug(redefine, class, annotation)("catch_target: exception_table_index=%d", exception_table_index);
3115 } break;
3116
3117 case 0x43:
3118 // kind: type in instanceof expression
3119 // location: Code
3120 case 0x44:
3121 // kind: type in new expression
3122 // location: Code
3123 case 0x45:
3124 // kind: type in method reference expression using ::new
3125 // location: Code
3126 case 0x46:
3127 // kind: type in method reference expression using ::Identifier
3128 // location: Code
3129
3130 {
3131 // struct:
3132 // offset_target {
3133 // u2 offset;
3134 // }
3135 //
3136 if ((byte_i_ref + 2) > type_annotations_typeArray->length()) {
3137 log_debug(redefine, class, annotation)("length() is too small for a offset_target");
3138 return false;
3139 }
3140
3141 u2 offset = Bytes::get_Java_u2((address)
3142 type_annotations_typeArray->adr_at(byte_i_ref));
3143 byte_i_ref += 2;
3144
3145 log_debug(redefine, class, annotation)("offset_target: offset=%d", offset);
3146 } break;
3147
3148 case 0x47:
3149 // kind: type in cast expression
3150 // location: Code
3151 case 0x48:
3152 // kind: type argument for generic constructor in new expression or
3153 // explicit constructor invocation statement
3154 // location: Code
3155 case 0x49:
3156 // kind: type argument for generic method in method invocation expression
3157 // location: Code
3158 case 0x4A:
3159 // kind: type argument for generic constructor in method reference expression using ::new
3160 // location: Code
3161 case 0x4B:
3162 // kind: type argument for generic method in method reference expression using ::Identifier
3163 // location: Code
3164
3165 {
3166 // struct:
3167 // type_argument_target {
3168 // u2 offset;
3169 // u1 type_argument_index;
3170 // }
3171 //
3172 if ((byte_i_ref + 3) > type_annotations_typeArray->length()) {
3173 log_debug(redefine, class, annotation)("length() is too small for a type_argument_target");
3174 return false;
3175 }
3176
3177 u2 offset = Bytes::get_Java_u2((address)
3178 type_annotations_typeArray->adr_at(byte_i_ref));
3179 byte_i_ref += 2;
3180 u1 type_argument_index = type_annotations_typeArray->at(byte_i_ref);
3181 byte_i_ref += 1;
3182
3183 log_debug(redefine, class, annotation)
3184 ("type_argument_target: offset=%d, type_argument_index=%d", offset, type_argument_index);
3185 } break;
3186
3187 default:
3188 log_debug(redefine, class, annotation)("unknown target_type");
3189 #ifdef ASSERT
3190 ShouldNotReachHere();
3191 #endif
3192 return false;
3193 }
3194
3195 return true;
3196 } // end skip_type_annotation_target()
3197
3198
3199 // Read, verify and skip over the type_path part so that rewriting
3200 // can continue in the later parts of the struct.
3201 //
3202 // type_path {
3203 // u1 path_length;
3204 // {
3205 // u1 type_path_kind;
3206 // u1 type_argument_index;
3207 // } path[path_length];
3208 // }
3209 //
3210 bool VM_RedefineClasses::skip_type_annotation_type_path(
3211 AnnotationArray* type_annotations_typeArray, int &byte_i_ref) {
3212
3213 if ((byte_i_ref + 1) > type_annotations_typeArray->length()) {
3214 // not enough room for a path_length let alone the rest of the type_path
3215 log_debug(redefine, class, annotation)("length() is too small for a type_path");
3216 return false;
3217 }
3218
3219 u1 path_length = type_annotations_typeArray->at(byte_i_ref);
3220 byte_i_ref += 1;
3221
3222 log_debug(redefine, class, annotation)("type_path: path_length=%d", path_length);
3223
3224 int calc_path_length = 0;
3225 for (; calc_path_length < path_length; calc_path_length++) {
3226 if ((byte_i_ref + 1 + 1) > type_annotations_typeArray->length()) {
3227 // not enough room for a path
3228 log_debug(redefine, class, annotation)
3229 ("length() is too small for path entry %d of %d", calc_path_length, path_length);
3230 return false;
3231 }
3232
3233 u1 type_path_kind = type_annotations_typeArray->at(byte_i_ref);
3234 byte_i_ref += 1;
3235 u1 type_argument_index = type_annotations_typeArray->at(byte_i_ref);
3236 byte_i_ref += 1;
3237
3238 log_debug(redefine, class, annotation)
3239 ("type_path: path[%d]: type_path_kind=%d, type_argument_index=%d",
3240 calc_path_length, type_path_kind, type_argument_index);
3241
3242 if (type_path_kind > 3 || (type_path_kind != 3 && type_argument_index != 0)) {
3243 // not enough room for a path
3244 log_debug(redefine, class, annotation)("inconsistent type_path values");
3245 return false;
3246 }
3247 }
3248 assert(path_length == calc_path_length, "sanity check");
3249
3250 return true;
3251 } // end skip_type_annotation_type_path()
3252
3253
3254 // Rewrite constant pool references in the method's stackmap table.
3255 // These "structures" are adapted from the StackMapTable_attribute that
3256 // is described in section 4.8.4 of the 6.0 version of the VM spec
3257 // (dated 2005.10.26):
3258 // file:///net/quincunx.sfbay/export/gbracha/ClassFile-Java6.pdf
3259 //
3260 // stack_map {
3261 // u2 number_of_entries;
3262 // stack_map_frame entries[number_of_entries];
3263 // }
3264 //
3265 void VM_RedefineClasses::rewrite_cp_refs_in_stack_map_table(
3266 const methodHandle& method) {
3267
3268 if (!method->has_stackmap_table()) {
3269 return;
3270 }
3271
3272 AnnotationArray* stackmap_data = method->stackmap_data();
3273 address stackmap_p = (address)stackmap_data->adr_at(0);
3274 address stackmap_end = stackmap_p + stackmap_data->length();
3275
3276 assert(stackmap_p + 2 <= stackmap_end, "no room for number_of_entries");
3277 u2 number_of_entries = Bytes::get_Java_u2(stackmap_p);
3278 stackmap_p += 2;
3279
3280 log_debug(redefine, class, stackmap)("number_of_entries=%u", number_of_entries);
3281
3282 // walk through each stack_map_frame
3283 u2 calc_number_of_entries = 0;
3284 for (; calc_number_of_entries < number_of_entries; calc_number_of_entries++) {
3285 // The stack_map_frame structure is a u1 frame_type followed by
3286 // 0 or more bytes of data:
3287 //
3288 // union stack_map_frame {
3289 // same_frame;
3290 // same_locals_1_stack_item_frame;
3291 // same_locals_1_stack_item_frame_extended;
3292 // chop_frame;
3293 // same_frame_extended;
3294 // append_frame;
3295 // full_frame;
3296 // }
3297
3298 assert(stackmap_p + 1 <= stackmap_end, "no room for frame_type");
3299 u1 frame_type = *stackmap_p;
3300 stackmap_p++;
3301
3302 // same_frame {
3303 // u1 frame_type = SAME; /* 0-63 */
3304 // }
3305 if (frame_type <= 63) {
3306 // nothing more to do for same_frame
3307 }
3308
3309 // same_locals_1_stack_item_frame {
3310 // u1 frame_type = SAME_LOCALS_1_STACK_ITEM; /* 64-127 */
3311 // verification_type_info stack[1];
3312 // }
3313 else if (frame_type >= 64 && frame_type <= 127) {
3314 rewrite_cp_refs_in_verification_type_info(stackmap_p, stackmap_end,
3315 calc_number_of_entries, frame_type);
3316 }
3317
3318 // reserved for future use
3319 else if (frame_type >= 128 && frame_type <= 246) {
3320 // nothing more to do for reserved frame_types
3321 }
3322
3323 // same_locals_1_stack_item_frame_extended {
3324 // u1 frame_type = SAME_LOCALS_1_STACK_ITEM_EXTENDED; /* 247 */
3325 // u2 offset_delta;
3326 // verification_type_info stack[1];
3327 // }
3328 else if (frame_type == 247) {
3329 stackmap_p += 2;
3330 rewrite_cp_refs_in_verification_type_info(stackmap_p, stackmap_end,
3331 calc_number_of_entries, frame_type);
3332 }
3333
3334 // chop_frame {
3335 // u1 frame_type = CHOP; /* 248-250 */
3336 // u2 offset_delta;
3337 // }
3338 else if (frame_type >= 248 && frame_type <= 250) {
3339 stackmap_p += 2;
3340 }
3341
3342 // same_frame_extended {
3343 // u1 frame_type = SAME_FRAME_EXTENDED; /* 251*/
3344 // u2 offset_delta;
3345 // }
3346 else if (frame_type == 251) {
3347 stackmap_p += 2;
3348 }
3349
3350 // append_frame {
3351 // u1 frame_type = APPEND; /* 252-254 */
3352 // u2 offset_delta;
3353 // verification_type_info locals[frame_type - 251];
3354 // }
3355 else if (frame_type >= 252 && frame_type <= 254) {
3356 assert(stackmap_p + 2 <= stackmap_end,
3357 "no room for offset_delta");
3358 stackmap_p += 2;
3359 u1 len = frame_type - 251;
3360 for (u1 i = 0; i < len; i++) {
3361 rewrite_cp_refs_in_verification_type_info(stackmap_p, stackmap_end,
3362 calc_number_of_entries, frame_type);
3363 }
3364 }
3365
3366 // full_frame {
3367 // u1 frame_type = FULL_FRAME; /* 255 */
3368 // u2 offset_delta;
3369 // u2 number_of_locals;
3370 // verification_type_info locals[number_of_locals];
3371 // u2 number_of_stack_items;
3372 // verification_type_info stack[number_of_stack_items];
3373 // }
3374 else if (frame_type == 255) {
3375 assert(stackmap_p + 2 + 2 <= stackmap_end,
3376 "no room for smallest full_frame");
3377 stackmap_p += 2;
3378
3379 u2 number_of_locals = Bytes::get_Java_u2(stackmap_p);
3380 stackmap_p += 2;
3381
3382 for (u2 locals_i = 0; locals_i < number_of_locals; locals_i++) {
3383 rewrite_cp_refs_in_verification_type_info(stackmap_p, stackmap_end,
3384 calc_number_of_entries, frame_type);
3385 }
3386
3387 // Use the largest size for the number_of_stack_items, but only get
3388 // the right number of bytes.
3389 u2 number_of_stack_items = Bytes::get_Java_u2(stackmap_p);
3390 stackmap_p += 2;
3391
3392 for (u2 stack_i = 0; stack_i < number_of_stack_items; stack_i++) {
3393 rewrite_cp_refs_in_verification_type_info(stackmap_p, stackmap_end,
3394 calc_number_of_entries, frame_type);
3395 }
3396 }
3397 } // end while there is a stack_map_frame
3398 assert(number_of_entries == calc_number_of_entries, "sanity check");
3399 } // end rewrite_cp_refs_in_stack_map_table()
3400
3401
3402 // Rewrite constant pool references in the verification type info
3403 // portion of the method's stackmap table. These "structures" are
3404 // adapted from the StackMapTable_attribute that is described in
3405 // section 4.8.4 of the 6.0 version of the VM spec (dated 2005.10.26):
3406 // file:///net/quincunx.sfbay/export/gbracha/ClassFile-Java6.pdf
3407 //
3408 // The verification_type_info structure is a u1 tag followed by 0 or
3409 // more bytes of data:
3410 //
3411 // union verification_type_info {
3412 // Top_variable_info;
3413 // Integer_variable_info;
3414 // Float_variable_info;
3415 // Long_variable_info;
3416 // Double_variable_info;
3417 // Null_variable_info;
3418 // UninitializedThis_variable_info;
3419 // Object_variable_info;
3420 // Uninitialized_variable_info;
3421 // }
3422 //
3423 void VM_RedefineClasses::rewrite_cp_refs_in_verification_type_info(
3424 address& stackmap_p_ref, address stackmap_end, u2 frame_i,
3425 u1 frame_type) {
3426
3427 assert(stackmap_p_ref + 1 <= stackmap_end, "no room for tag");
3428 u1 tag = *stackmap_p_ref;
3429 stackmap_p_ref++;
3430
3431 switch (tag) {
3432 // Top_variable_info {
3433 // u1 tag = ITEM_Top; /* 0 */
3434 // }
3435 // verificationType.hpp has zero as ITEM_Bogus instead of ITEM_Top
3436 case 0: // fall through
3437
3438 // Integer_variable_info {
3439 // u1 tag = ITEM_Integer; /* 1 */
3440 // }
3441 case ITEM_Integer: // fall through
3442
3443 // Float_variable_info {
3444 // u1 tag = ITEM_Float; /* 2 */
3445 // }
3446 case ITEM_Float: // fall through
3447
3448 // Double_variable_info {
3449 // u1 tag = ITEM_Double; /* 3 */
3450 // }
3451 case ITEM_Double: // fall through
3452
3453 // Long_variable_info {
3454 // u1 tag = ITEM_Long; /* 4 */
3455 // }
3456 case ITEM_Long: // fall through
3457
3458 // Null_variable_info {
3459 // u1 tag = ITEM_Null; /* 5 */
3460 // }
3461 case ITEM_Null: // fall through
3462
3463 // UninitializedThis_variable_info {
3464 // u1 tag = ITEM_UninitializedThis; /* 6 */
3465 // }
3466 case ITEM_UninitializedThis:
3467 // nothing more to do for the above tag types
3468 break;
3469
3470 // Object_variable_info {
3471 // u1 tag = ITEM_Object; /* 7 */
3472 // u2 cpool_index;
3473 // }
3474 case ITEM_Object:
3475 {
3476 assert(stackmap_p_ref + 2 <= stackmap_end, "no room for cpool_index");
3477 u2 cpool_index = Bytes::get_Java_u2(stackmap_p_ref);
3478 u2 new_cp_index = find_new_index(cpool_index);
3479 if (new_cp_index != 0) {
3480 log_debug(redefine, class, stackmap)("mapped old cpool_index=%d", cpool_index);
3481 Bytes::put_Java_u2(stackmap_p_ref, new_cp_index);
3482 cpool_index = new_cp_index;
3483 }
3484 stackmap_p_ref += 2;
3485
3486 log_debug(redefine, class, stackmap)
3487 ("frame_i=%u, frame_type=%u, cpool_index=%d", frame_i, frame_type, cpool_index);
3488 } break;
3489
3490 // Uninitialized_variable_info {
3491 // u1 tag = ITEM_Uninitialized; /* 8 */
3492 // u2 offset;
3493 // }
3494 case ITEM_Uninitialized:
3495 assert(stackmap_p_ref + 2 <= stackmap_end, "no room for offset");
3496 stackmap_p_ref += 2;
3497 break;
3498
3499 default:
3500 log_debug(redefine, class, stackmap)("frame_i=%u, frame_type=%u, bad tag=0x%x", frame_i, frame_type, tag);
3501 ShouldNotReachHere();
3502 break;
3503 } // end switch (tag)
3504 } // end rewrite_cp_refs_in_verification_type_info()
3505
3506
3507 // Change the constant pool associated with klass scratch_class to scratch_cp.
3508 // scratch_cp_length elements are copied from scratch_cp to a smaller constant pool
3509 // and the smaller constant pool is associated with scratch_class.
3510 void VM_RedefineClasses::set_new_constant_pool(
3511 ClassLoaderData* loader_data,
3512 InstanceKlass* scratch_class, constantPoolHandle scratch_cp,
3513 int scratch_cp_length, TRAPS) {
3514 assert(scratch_cp->length() >= scratch_cp_length, "sanity check");
3515
3516 // scratch_cp is a merged constant pool and has enough space for a
3517 // worst case merge situation. We want to associate the minimum
3518 // sized constant pool with the klass to save space.
3519 ConstantPool* cp = ConstantPool::allocate(loader_data, scratch_cp_length, CHECK);
3520 constantPoolHandle smaller_cp(THREAD, cp);
3521
3522 // preserve version() value in the smaller copy
3523 int version = scratch_cp->version();
3524 assert(version != 0, "sanity check");
3525 smaller_cp->set_version(version);
3526
3527 // attach klass to new constant pool
3528 // reference to the cp holder is needed for copy_operands()
3529 smaller_cp->set_pool_holder(scratch_class);
3530
3531 smaller_cp->copy_fields(scratch_cp());
3532
3533 scratch_cp->copy_cp_to(1, scratch_cp_length - 1, smaller_cp, 1, THREAD);
3534 if (HAS_PENDING_EXCEPTION) {
3535 // Exception is handled in the caller
3536 loader_data->add_to_deallocate_list(smaller_cp());
3537 return;
3538 }
3539 scratch_cp = smaller_cp;
3540
3541 // attach new constant pool to klass
3542 scratch_class->set_constants(scratch_cp());
3543 scratch_cp->initialize_unresolved_klasses(loader_data, CHECK);
3544
3545 int i; // for portability
3546
3547 // update each field in klass to use new constant pool indices as needed
3548 int java_fields;
3549 int injected_fields;
3550 bool update_required = false;
3551 GrowableArray<FieldInfo>* fields = FieldInfoStream::create_FieldInfoArray(scratch_class->fieldinfo_stream(), &java_fields, &injected_fields);
3552 for (int i = 0; i < java_fields; i++) {
3553 FieldInfo* fi = fields->adr_at(i);
3554 jshort cur_index = fi->name_index();
3555 jshort new_index = find_new_index(cur_index);
3556 if (new_index != 0) {
3557 log_trace(redefine, class, constantpool)("field-name_index change: %d to %d", cur_index, new_index);
3558 fi->set_name_index(new_index);
3559 update_required = true;
3560 }
3561 cur_index = fi->signature_index();
3562 new_index = find_new_index(cur_index);
3563 if (new_index != 0) {
3564 log_trace(redefine, class, constantpool)("field-signature_index change: %d to %d", cur_index, new_index);
3565 fi->set_signature_index(new_index);
3566 update_required = true;
3567 }
3568 cur_index = fi->initializer_index();
3569 new_index = find_new_index(cur_index);
3570 if (new_index != 0) {
3571 log_trace(redefine, class, constantpool)("field-initval_index change: %d to %d", cur_index, new_index);
3572 fi->set_initializer_index(new_index);
3573 update_required = true;
3574 }
3575 cur_index = fi->generic_signature_index();
3576 new_index = find_new_index(cur_index);
3577 if (new_index != 0) {
3578 log_trace(redefine, class, constantpool)("field-generic_signature change: %d to %d", cur_index, new_index);
3579 fi->set_generic_signature_index(new_index);
3580 update_required = true;
3581 }
3582 }
3583 if (update_required) {
3584 Array<u1>* old_stream = scratch_class->fieldinfo_stream();
3585 assert(fields->length() == (java_fields + injected_fields), "Must be");
3586 Array<u1>* new_fis = FieldInfoStream::create_FieldInfoStream(fields, java_fields, injected_fields, scratch_class->class_loader_data(), CHECK);
3587 scratch_class->set_fieldinfo_stream(new_fis);
3588 MetadataFactory::free_array<u1>(scratch_class->class_loader_data(), old_stream);
3589 }
3590
3591 // Update constant pool indices in the inner classes info to use
3592 // new constant indices as needed. The inner classes info is a
3593 // quadruple:
3594 // (inner_class_info, outer_class_info, inner_name, inner_access_flags)
3595 InnerClassesIterator iter(scratch_class);
3596 for (; !iter.done(); iter.next()) {
3597 int cur_index = iter.inner_class_info_index();
3598 if (cur_index == 0) {
3599 continue; // JVM spec. allows null inner class refs so skip it
3600 }
3601 u2 new_index = find_new_index(cur_index);
3602 if (new_index != 0) {
3603 log_trace(redefine, class, constantpool)("inner_class_info change: %d to %d", cur_index, new_index);
3604 iter.set_inner_class_info_index(new_index);
3605 }
3606 cur_index = iter.outer_class_info_index();
3607 new_index = find_new_index(cur_index);
3608 if (new_index != 0) {
3609 log_trace(redefine, class, constantpool)("outer_class_info change: %d to %d", cur_index, new_index);
3610 iter.set_outer_class_info_index(new_index);
3611 }
3612 cur_index = iter.inner_name_index();
3613 new_index = find_new_index(cur_index);
3614 if (new_index != 0) {
3615 log_trace(redefine, class, constantpool)("inner_name change: %d to %d", cur_index, new_index);
3616 iter.set_inner_name_index(new_index);
3617 }
3618 } // end for each inner class
3619
3620 // Attach each method in klass to the new constant pool and update
3621 // to use new constant pool indices as needed:
3622 Array<Method*>* methods = scratch_class->methods();
3623 for (i = methods->length() - 1; i >= 0; i--) {
3624 methodHandle method(THREAD, methods->at(i));
3625 method->set_constants(scratch_cp());
3626
3627 u2 new_index = find_new_index(method->name_index());
3628 if (new_index != 0) {
3629 log_trace(redefine, class, constantpool)
3630 ("method-name_index change: %d to %d", method->name_index(), new_index);
3631 method->set_name_index(new_index);
3632 }
3633 new_index = find_new_index(method->signature_index());
3634 if (new_index != 0) {
3635 log_trace(redefine, class, constantpool)
3636 ("method-signature_index change: %d to %d", method->signature_index(), new_index);
3637 method->set_signature_index(new_index);
3638 }
3639 new_index = find_new_index(method->generic_signature_index());
3640 if (new_index != 0) {
3641 log_trace(redefine, class, constantpool)
3642 ("method-generic_signature_index change: %d to %d", method->generic_signature_index(), new_index);
3643 method->constMethod()->set_generic_signature_index(new_index);
3644 }
3645
3646 // Update constant pool indices in the method's checked exception
3647 // table to use new constant indices as needed.
3648 int cext_length = method->checked_exceptions_length();
3649 if (cext_length > 0) {
3650 CheckedExceptionElement * cext_table =
3651 method->checked_exceptions_start();
3652 for (int j = 0; j < cext_length; j++) {
3653 int cur_index = cext_table[j].class_cp_index;
3654 int new_index = find_new_index(cur_index);
3655 if (new_index != 0) {
3656 log_trace(redefine, class, constantpool)("cext-class_cp_index change: %d to %d", cur_index, new_index);
3657 cext_table[j].class_cp_index = (u2)new_index;
3658 }
3659 } // end for each checked exception table entry
3660 } // end if there are checked exception table entries
3661
3662 // Update each catch type index in the method's exception table
3663 // to use new constant pool indices as needed. The exception table
3664 // holds quadruple entries of the form:
3665 // (beg_bci, end_bci, handler_bci, klass_index)
3666
3667 ExceptionTable ex_table(method());
3668 int ext_length = ex_table.length();
3669
3670 for (int j = 0; j < ext_length; j ++) {
3671 int cur_index = ex_table.catch_type_index(j);
3672 u2 new_index = find_new_index(cur_index);
3673 if (new_index != 0) {
3674 log_trace(redefine, class, constantpool)("ext-klass_index change: %d to %d", cur_index, new_index);
3675 ex_table.set_catch_type_index(j, new_index);
3676 }
3677 } // end for each exception table entry
3678
3679 // Update constant pool indices in the method's local variable
3680 // table to use new constant indices as needed. The local variable
3681 // table hold sextuple entries of the form:
3682 // (start_pc, length, name_index, descriptor_index, signature_index, slot)
3683 int lvt_length = method->localvariable_table_length();
3684 if (lvt_length > 0) {
3685 LocalVariableTableElement * lv_table =
3686 method->localvariable_table_start();
3687 for (int j = 0; j < lvt_length; j++) {
3688 int cur_index = lv_table[j].name_cp_index;
3689 int new_index = find_new_index(cur_index);
3690 if (new_index != 0) {
3691 log_trace(redefine, class, constantpool)("lvt-name_cp_index change: %d to %d", cur_index, new_index);
3692 lv_table[j].name_cp_index = (u2)new_index;
3693 }
3694 cur_index = lv_table[j].descriptor_cp_index;
3695 new_index = find_new_index(cur_index);
3696 if (new_index != 0) {
3697 log_trace(redefine, class, constantpool)("lvt-descriptor_cp_index change: %d to %d", cur_index, new_index);
3698 lv_table[j].descriptor_cp_index = (u2)new_index;
3699 }
3700 cur_index = lv_table[j].signature_cp_index;
3701 new_index = find_new_index(cur_index);
3702 if (new_index != 0) {
3703 log_trace(redefine, class, constantpool)("lvt-signature_cp_index change: %d to %d", cur_index, new_index);
3704 lv_table[j].signature_cp_index = (u2)new_index;
3705 }
3706 } // end for each local variable table entry
3707 } // end if there are local variable table entries
3708
3709 // Update constant pool indices in the method's method_parameters.
3710 int mp_length = method->method_parameters_length();
3711 if (mp_length > 0) {
3712 MethodParametersElement* elem = method->method_parameters_start();
3713 for (int j = 0; j < mp_length; j++) {
3714 const int cp_index = elem[j].name_cp_index;
3715 const int new_cp_index = find_new_index(cp_index);
3716 if (new_cp_index != 0) {
3717 elem[j].name_cp_index = (u2)new_cp_index;
3718 }
3719 }
3720 }
3721
3722 rewrite_cp_refs_in_stack_map_table(method);
3723 } // end for each method
3724 } // end set_new_constant_pool()
3725
3726
3727 // Unevolving classes may point to methods of the_class directly
3728 // from their constant pool caches, itables, and/or vtables. We
3729 // use the ClassLoaderDataGraph::classes_do() facility and this helper
3730 // to fix up these pointers. MethodData also points to old methods and
3731 // must be cleaned.
3732
3733 // Adjust cpools and vtables closure
3734 void VM_RedefineClasses::AdjustAndCleanMetadata::do_klass(Klass* k) {
3735
3736 // This is a very busy routine. We don't want too much tracing
3737 // printed out.
3738 bool trace_name_printed = false;
3739
3740 // If the class being redefined is java.lang.Object, we need to fix all
3741 // array class vtables also. The _has_redefined_Object flag is global.
3742 // Once the java.lang.Object has been redefined (by the current or one
3743 // of the previous VM_RedefineClasses operations) we have to always
3744 // adjust method entries for array classes.
3745 if (k->is_array_klass() && _has_redefined_Object) {
3746 k->vtable().adjust_method_entries(&trace_name_printed);
3747
3748 } else if (k->is_instance_klass()) {
3749 HandleMark hm(_thread);
3750 InstanceKlass *ik = InstanceKlass::cast(k);
3751
3752 // Clean MethodData of this class's methods so they don't refer to
3753 // old methods that are no longer running.
3754 Array<Method*>* methods = ik->methods();
3755 int num_methods = methods->length();
3756 for (int index = 0; index < num_methods; ++index) {
3757 if (methods->at(index)->method_data() != nullptr) {
3758 methods->at(index)->method_data()->clean_weak_method_links();
3759 }
3760 }
3761
3762 // Adjust all vtables, default methods and itables, to clean out old methods.
3763 ResourceMark rm(_thread);
3764 if (ik->vtable_length() > 0) {
3765 ik->vtable().adjust_method_entries(&trace_name_printed);
3766 ik->adjust_default_methods(&trace_name_printed);
3767 }
3768
3769 if (ik->itable_length() > 0) {
3770 ik->itable().adjust_method_entries(&trace_name_printed);
3771 }
3772
3773 // The constant pools in other classes (other_cp) can refer to
3774 // old methods. We have to update method information in
3775 // other_cp's cache. If other_cp has a previous version, then we
3776 // have to repeat the process for each previous version. The
3777 // constant pool cache holds the Method*s for non-virtual
3778 // methods and for virtual, final methods.
3779 //
3780 // Special case: if the current class is being redefined by the current
3781 // VM_RedefineClasses operation, then new_cp has already been attached
3782 // to the_class and old_cp has already been added as a previous version.
3783 // The new_cp doesn't have any cached references to old methods so it
3784 // doesn't need to be updated and we could optimize by skipping it.
3785 // However, the current class can be marked as being redefined by another
3786 // VM_RedefineClasses operation which has already executed its doit_prologue
3787 // and needs cpcache method entries adjusted. For simplicity, the cpcache
3788 // update is done unconditionally. It should result in doing nothing for
3789 // classes being redefined by the current VM_RedefineClasses operation.
3790 // Method entries in the previous version(s) are adjusted as well.
3791 ConstantPoolCache* cp_cache;
3792
3793 // this klass' constant pool cache may need adjustment
3794 ConstantPool* other_cp = ik->constants();
3795 cp_cache = other_cp->cache();
3796 if (cp_cache != nullptr) {
3797 cp_cache->adjust_method_entries(&trace_name_printed);
3798 }
3799
3800 // the previous versions' constant pool caches may need adjustment
3801 for (InstanceKlass* pv_node = ik->previous_versions();
3802 pv_node != nullptr;
3803 pv_node = pv_node->previous_versions()) {
3804 cp_cache = pv_node->constants()->cache();
3805 if (cp_cache != nullptr) {
3806 cp_cache->adjust_method_entries(&trace_name_printed);
3807 }
3808 }
3809 }
3810 }
3811
3812 void VM_RedefineClasses::update_jmethod_ids() {
3813 for (int j = 0; j < _matching_methods_length; ++j) {
3814 Method* old_method = _matching_old_methods[j];
3815 jmethodID jmid = old_method->find_jmethod_id_or_null();
3816 if (jmid != nullptr) {
3817 // There is a jmethodID, change it to point to the new method
3818 Method* new_method = _matching_new_methods[j];
3819 Method::change_method_associated_with_jmethod_id(jmid, new_method);
3820 assert(Method::resolve_jmethod_id(jmid) == _matching_new_methods[j],
3821 "should be replaced");
3822 }
3823 }
3824 }
3825
3826 int VM_RedefineClasses::check_methods_and_mark_as_obsolete() {
3827 int emcp_method_count = 0;
3828 int obsolete_count = 0;
3829 int old_index = 0;
3830 for (int j = 0; j < _matching_methods_length; ++j, ++old_index) {
3831 Method* old_method = _matching_old_methods[j];
3832 Method* new_method = _matching_new_methods[j];
3833 Method* old_array_method;
3834
3835 // Maintain an old_index into the _old_methods array by skipping
3836 // deleted methods
3837 while ((old_array_method = _old_methods->at(old_index)) != old_method) {
3838 ++old_index;
3839 }
3840
3841 if (MethodComparator::methods_EMCP(old_method, new_method)) {
3842 // The EMCP definition from JSR-163 requires the bytecodes to be
3843 // the same with the exception of constant pool indices which may
3844 // differ. However, the constants referred to by those indices
3845 // must be the same.
3846 //
3847 // We use methods_EMCP() for comparison since constant pool
3848 // merging can remove duplicate constant pool entries that were
3849 // present in the old method and removed from the rewritten new
3850 // method. A faster binary comparison function would consider the
3851 // old and new methods to be different when they are actually
3852 // EMCP.
3853 //
3854 // The old and new methods are EMCP and you would think that we
3855 // could get rid of one of them here and now and save some space.
3856 // However, the concept of EMCP only considers the bytecodes and
3857 // the constant pool entries in the comparison. Other things,
3858 // e.g., the line number table (LNT) or the local variable table
3859 // (LVT) don't count in the comparison. So the new (and EMCP)
3860 // method can have a new LNT that we need so we can't just
3861 // overwrite the new method with the old method.
3862 //
3863 // When this routine is called, we have already attached the new
3864 // methods to the_class so the old methods are effectively
3865 // overwritten. However, if an old method is still executing,
3866 // then the old method cannot be collected until sometime after
3867 // the old method call has returned. So the overwriting of old
3868 // methods by new methods will save us space except for those
3869 // (hopefully few) old methods that are still executing.
3870 //
3871 // A method refers to a ConstMethod* and this presents another
3872 // possible avenue to space savings. The ConstMethod* in the
3873 // new method contains possibly new attributes (LNT, LVT, etc).
3874 // At first glance, it seems possible to save space by replacing
3875 // the ConstMethod* in the old method with the ConstMethod*
3876 // from the new method. The old and new methods would share the
3877 // same ConstMethod* and we would save the space occupied by
3878 // the old ConstMethod*. However, the ConstMethod* contains
3879 // a back reference to the containing method. Sharing the
3880 // ConstMethod* between two methods could lead to confusion in
3881 // the code that uses the back reference. This would lead to
3882 // brittle code that could be broken in non-obvious ways now or
3883 // in the future.
3884 //
3885 // Another possibility is to copy the ConstMethod* from the new
3886 // method to the old method and then overwrite the new method with
3887 // the old method. Since the ConstMethod* contains the bytecodes
3888 // for the method embedded in the oop, this option would change
3889 // the bytecodes out from under any threads executing the old
3890 // method and make the thread's bcp invalid. Since EMCP requires
3891 // that the bytecodes be the same modulo constant pool indices, it
3892 // is straight forward to compute the correct new bcp in the new
3893 // ConstMethod* from the old bcp in the old ConstMethod*. The
3894 // time consuming part would be searching all the frames in all
3895 // of the threads to find all of the calls to the old method.
3896 //
3897 // It looks like we will have to live with the limited savings
3898 // that we get from effectively overwriting the old methods
3899 // when the new methods are attached to the_class.
3900
3901 // Count number of methods that are EMCP. The method will be marked
3902 // old but not obsolete if it is EMCP.
3903 emcp_method_count++;
3904
3905 // An EMCP method is _not_ obsolete. An obsolete method has a
3906 // different jmethodID than the current method. An EMCP method
3907 // has the same jmethodID as the current method. Having the
3908 // same jmethodID for all EMCP versions of a method allows for
3909 // a consistent view of the EMCP methods regardless of which
3910 // EMCP method you happen to have in hand. For example, a
3911 // breakpoint set in one EMCP method will work for all EMCP
3912 // versions of the method including the current one.
3913 } else {
3914 // mark obsolete methods as such
3915 old_method->set_is_obsolete();
3916 obsolete_count++;
3917
3918 // obsolete methods need a unique idnum so they become new entries in
3919 // the jmethodID cache in InstanceKlass
3920 assert(old_method->method_idnum() == new_method->method_idnum(), "must match");
3921 u2 num = InstanceKlass::cast(_the_class)->next_method_idnum();
3922 if (num != ConstMethod::UNSET_IDNUM) {
3923 old_method->set_method_idnum(num);
3924 }
3925
3926 // With tracing we try not to "yack" too much. The position of
3927 // this trace assumes there are fewer obsolete methods than
3928 // EMCP methods.
3929 if (log_is_enabled(Trace, redefine, class, obsolete, mark)) {
3930 ResourceMark rm;
3931 log_trace(redefine, class, obsolete, mark)
3932 ("mark %s(%s) as obsolete", old_method->name()->as_C_string(), old_method->signature()->as_C_string());
3933 }
3934 }
3935 old_method->set_is_old();
3936 }
3937 for (int i = 0; i < _deleted_methods_length; ++i) {
3938 Method* old_method = _deleted_methods[i];
3939
3940 assert(!old_method->has_vtable_index(),
3941 "cannot delete methods with vtable entries");;
3942
3943 // Mark all deleted methods as old, obsolete and deleted
3944 old_method->set_is_deleted();
3945 old_method->set_is_old();
3946 old_method->set_is_obsolete();
3947 ++obsolete_count;
3948 // With tracing we try not to "yack" too much. The position of
3949 // this trace assumes there are fewer obsolete methods than
3950 // EMCP methods.
3951 if (log_is_enabled(Trace, redefine, class, obsolete, mark)) {
3952 ResourceMark rm;
3953 log_trace(redefine, class, obsolete, mark)
3954 ("mark deleted %s(%s) as obsolete", old_method->name()->as_C_string(), old_method->signature()->as_C_string());
3955 }
3956 }
3957 assert((emcp_method_count + obsolete_count) == _old_methods->length(),
3958 "sanity check");
3959 log_trace(redefine, class, obsolete, mark)("EMCP_cnt=%d, obsolete_cnt=%d", emcp_method_count, obsolete_count);
3960 return emcp_method_count;
3961 }
3962
3963 // This internal class transfers the native function registration from old methods
3964 // to new methods. It is designed to handle both the simple case of unchanged
3965 // native methods and the complex cases of native method prefixes being added and/or
3966 // removed.
3967 // It expects only to be used during the VM_RedefineClasses op (a safepoint).
3968 //
3969 // This class is used after the new methods have been installed in "the_class".
3970 //
3971 // So, for example, the following must be handled. Where 'm' is a method and
3972 // a number followed by an underscore is a prefix.
3973 //
3974 // Old Name New Name
3975 // Simple transfer to new method m -> m
3976 // Add prefix m -> 1_m
3977 // Remove prefix 1_m -> m
3978 // Simultaneous add of prefixes m -> 3_2_1_m
3979 // Simultaneous removal of prefixes 3_2_1_m -> m
3980 // Simultaneous add and remove 1_m -> 2_m
3981 // Same, caused by prefix removal only 3_2_1_m -> 3_2_m
3982 //
3983 class TransferNativeFunctionRegistration {
3984 private:
3985 InstanceKlass* the_class;
3986 int prefix_count;
3987 char** prefixes;
3988
3989 // Recursively search the binary tree of possibly prefixed method names.
3990 // Iteration could be used if all agents were well behaved. Full tree walk is
3991 // more resilent to agents not cleaning up intermediate methods.
3992 // Branch at each depth in the binary tree is:
3993 // (1) without the prefix.
3994 // (2) with the prefix.
3995 // where 'prefix' is the prefix at that 'depth' (first prefix, second prefix,...)
3996 Method* search_prefix_name_space(int depth, char* name_str, size_t name_len,
3997 Symbol* signature) {
3998 TempNewSymbol name_symbol = SymbolTable::probe(name_str, (int)name_len);
3999 if (name_symbol != nullptr) {
4000 Method* method = the_class->lookup_method(name_symbol, signature);
4001 if (method != nullptr) {
4002 // Even if prefixed, intermediate methods must exist.
4003 if (method->is_native()) {
4004 // Wahoo, we found a (possibly prefixed) version of the method, return it.
4005 return method;
4006 }
4007 if (depth < prefix_count) {
4008 // Try applying further prefixes (other than this one).
4009 method = search_prefix_name_space(depth+1, name_str, name_len, signature);
4010 if (method != nullptr) {
4011 return method; // found
4012 }
4013
4014 // Try adding this prefix to the method name and see if it matches
4015 // another method name.
4016 char* prefix = prefixes[depth];
4017 size_t prefix_len = strlen(prefix);
4018 size_t trial_len = name_len + prefix_len;
4019 char* trial_name_str = NEW_RESOURCE_ARRAY(char, trial_len + 1);
4020 strcpy(trial_name_str, prefix);
4021 strcat(trial_name_str, name_str);
4022 method = search_prefix_name_space(depth+1, trial_name_str, trial_len,
4023 signature);
4024 if (method != nullptr) {
4025 // If found along this branch, it was prefixed, mark as such
4026 method->set_is_prefixed_native();
4027 return method; // found
4028 }
4029 }
4030 }
4031 }
4032 return nullptr; // This whole branch bore nothing
4033 }
4034
4035 // Return the method name with old prefixes stripped away.
4036 char* method_name_without_prefixes(Method* method) {
4037 Symbol* name = method->name();
4038 char* name_str = name->as_utf8();
4039
4040 // Old prefixing may be defunct, strip prefixes, if any.
4041 for (int i = prefix_count-1; i >= 0; i--) {
4042 char* prefix = prefixes[i];
4043 size_t prefix_len = strlen(prefix);
4044 if (strncmp(prefix, name_str, prefix_len) == 0) {
4045 name_str += prefix_len;
4046 }
4047 }
4048 return name_str;
4049 }
4050
4051 // Strip any prefixes off the old native method, then try to find a
4052 // (possibly prefixed) new native that matches it.
4053 Method* strip_and_search_for_new_native(Method* method) {
4054 ResourceMark rm;
4055 char* name_str = method_name_without_prefixes(method);
4056 return search_prefix_name_space(0, name_str, strlen(name_str),
4057 method->signature());
4058 }
4059
4060 public:
4061
4062 // Construct a native method transfer processor for this class.
4063 TransferNativeFunctionRegistration(InstanceKlass* _the_class) {
4064 assert(SafepointSynchronize::is_at_safepoint(), "sanity check");
4065
4066 the_class = _the_class;
4067 prefixes = JvmtiExport::get_all_native_method_prefixes(&prefix_count);
4068 }
4069
4070 // Attempt to transfer any of the old or deleted methods that are native
4071 void transfer_registrations(Method** old_methods, int methods_length) {
4072 for (int j = 0; j < methods_length; j++) {
4073 Method* old_method = old_methods[j];
4074
4075 if (old_method->is_native() && old_method->has_native_function()) {
4076 Method* new_method = strip_and_search_for_new_native(old_method);
4077 if (new_method != nullptr) {
4078 // Actually set the native function in the new method.
4079 // Redefine does not send events (except CFLH), certainly not this
4080 // behind the scenes re-registration.
4081 new_method->set_native_function(old_method->native_function(),
4082 !Method::native_bind_event_is_interesting);
4083 }
4084 }
4085 }
4086 }
4087 };
4088
4089 // Don't lose the association between a native method and its JNI function.
4090 void VM_RedefineClasses::transfer_old_native_function_registrations(InstanceKlass* the_class) {
4091 TransferNativeFunctionRegistration transfer(the_class);
4092 transfer.transfer_registrations(_deleted_methods, _deleted_methods_length);
4093 transfer.transfer_registrations(_matching_old_methods, _matching_methods_length);
4094 }
4095
4096 // Deoptimize all compiled code that depends on the classes redefined.
4097 //
4098 // If the can_redefine_classes capability is obtained in the onload
4099 // phase then the compiler has recorded all dependencies from startup.
4100 // In that case we need only deoptimize and throw away all compiled code
4101 // that depends on the class.
4102 //
4103 // If can_redefine_classes is obtained sometime after the onload
4104 // phase then the dependency information may be incomplete. In that case
4105 // the first call to RedefineClasses causes all compiled code to be
4106 // thrown away. As can_redefine_classes has been obtained then
4107 // all future compilations will record dependencies so second and
4108 // subsequent calls to RedefineClasses need only throw away code
4109 // that depends on the class.
4110 //
4111
4112 void VM_RedefineClasses::flush_dependent_code() {
4113 assert(SafepointSynchronize::is_at_safepoint(), "sanity check");
4114
4115 DeoptimizationScope deopt_scope;
4116
4117 // This is the first redefinition, mark all the nmethods for deoptimization
4118 if (!JvmtiExport::all_dependencies_are_recorded()) {
4119 CodeCache::mark_all_nmethods_for_evol_deoptimization(&deopt_scope);
4120 log_debug(redefine, class, nmethod)("Marked all nmethods for deopt");
4121 } else {
4122 CodeCache::mark_dependents_for_evol_deoptimization(&deopt_scope);
4123 log_debug(redefine, class, nmethod)("Marked dependent nmethods for deopt");
4124 }
4125
4126 deopt_scope.deoptimize_marked();
4127
4128 // From now on we know that the dependency information is complete
4129 JvmtiExport::set_all_dependencies_are_recorded(true);
4130 }
4131
4132 void VM_RedefineClasses::compute_added_deleted_matching_methods() {
4133 Method* old_method;
4134 Method* new_method;
4135
4136 _matching_old_methods = NEW_RESOURCE_ARRAY(Method*, _old_methods->length());
4137 _matching_new_methods = NEW_RESOURCE_ARRAY(Method*, _old_methods->length());
4138 _added_methods = NEW_RESOURCE_ARRAY(Method*, _new_methods->length());
4139 _deleted_methods = NEW_RESOURCE_ARRAY(Method*, _old_methods->length());
4140
4141 _matching_methods_length = 0;
4142 _deleted_methods_length = 0;
4143 _added_methods_length = 0;
4144
4145 int nj = 0;
4146 int oj = 0;
4147 while (true) {
4148 if (oj >= _old_methods->length()) {
4149 if (nj >= _new_methods->length()) {
4150 break; // we've looked at everything, done
4151 }
4152 // New method at the end
4153 new_method = _new_methods->at(nj);
4154 _added_methods[_added_methods_length++] = new_method;
4155 ++nj;
4156 } else if (nj >= _new_methods->length()) {
4157 // Old method, at the end, is deleted
4158 old_method = _old_methods->at(oj);
4159 _deleted_methods[_deleted_methods_length++] = old_method;
4160 ++oj;
4161 } else {
4162 old_method = _old_methods->at(oj);
4163 new_method = _new_methods->at(nj);
4164 if (old_method->name() == new_method->name()) {
4165 if (old_method->signature() == new_method->signature()) {
4166 _matching_old_methods[_matching_methods_length ] = old_method;
4167 _matching_new_methods[_matching_methods_length++] = new_method;
4168 ++nj;
4169 ++oj;
4170 } else {
4171 // added overloaded have already been moved to the end,
4172 // so this is a deleted overloaded method
4173 _deleted_methods[_deleted_methods_length++] = old_method;
4174 ++oj;
4175 }
4176 } else { // names don't match
4177 if (old_method->name()->fast_compare(new_method->name()) > 0) {
4178 // new method
4179 _added_methods[_added_methods_length++] = new_method;
4180 ++nj;
4181 } else {
4182 // deleted method
4183 _deleted_methods[_deleted_methods_length++] = old_method;
4184 ++oj;
4185 }
4186 }
4187 }
4188 }
4189 assert(_matching_methods_length + _deleted_methods_length == _old_methods->length(), "sanity");
4190 assert(_matching_methods_length + _added_methods_length == _new_methods->length(), "sanity");
4191 }
4192
4193
4194 void VM_RedefineClasses::swap_annotations(InstanceKlass* the_class,
4195 InstanceKlass* scratch_class) {
4196 // Swap annotation fields values
4197 Annotations* old_annotations = the_class->annotations();
4198 the_class->set_annotations(scratch_class->annotations());
4199 scratch_class->set_annotations(old_annotations);
4200 }
4201
4202
4203 // Install the redefinition of a class:
4204 // - house keeping (flushing breakpoints and caches, deoptimizing
4205 // dependent compiled code)
4206 // - replacing parts in the_class with parts from scratch_class
4207 // - adding a weak reference to track the obsolete but interesting
4208 // parts of the_class
4209 // - adjusting constant pool caches and vtables in other classes
4210 // that refer to methods in the_class. These adjustments use the
4211 // ClassLoaderDataGraph::classes_do() facility which only allows
4212 // a helper method to be specified. The interesting parameters
4213 // that we would like to pass to the helper method are saved in
4214 // static global fields in the VM operation.
4215 void VM_RedefineClasses::redefine_single_class(Thread* current, jclass the_jclass,
4216 InstanceKlass* scratch_class) {
4217
4218 HandleMark hm(current); // make sure handles from this call are freed
4219
4220 if (log_is_enabled(Info, redefine, class, timer)) {
4221 _timer_rsc_phase1.start();
4222 }
4223
4224 InstanceKlass* the_class = get_ik(the_jclass);
4225
4226 // Set a flag to control and optimize adjusting method entries
4227 _has_redefined_Object |= the_class == vmClasses::Object_klass();
4228
4229 // Remove all breakpoints in methods of this class
4230 JvmtiBreakpoints& jvmti_breakpoints = JvmtiCurrentBreakpoints::get_jvmti_breakpoints();
4231 jvmti_breakpoints.clearall_in_class_at_safepoint(the_class);
4232
4233 _old_methods = the_class->methods();
4234 _new_methods = scratch_class->methods();
4235 _the_class = the_class;
4236 compute_added_deleted_matching_methods();
4237 update_jmethod_ids();
4238
4239 _any_class_has_resolved_methods = the_class->has_resolved_methods() || _any_class_has_resolved_methods;
4240
4241 // Attach new constant pool to the original klass. The original
4242 // klass still refers to the old constant pool (for now).
4243 scratch_class->constants()->set_pool_holder(the_class);
4244
4245 #if 0
4246 // In theory, with constant pool merging in place we should be able
4247 // to save space by using the new, merged constant pool in place of
4248 // the old constant pool(s). By "pool(s)" I mean the constant pool in
4249 // the klass version we are replacing now and any constant pool(s) in
4250 // previous versions of klass. Nice theory, doesn't work in practice.
4251 // When this code is enabled, even simple programs throw NullPointer
4252 // exceptions. I'm guessing that this is caused by some constant pool
4253 // cache difference between the new, merged constant pool and the
4254 // constant pool that was just being used by the klass. I'm keeping
4255 // this code around to archive the idea, but the code has to remain
4256 // disabled for now.
4257
4258 // Attach each old method to the new constant pool. This can be
4259 // done here since we are past the bytecode verification and
4260 // constant pool optimization phases.
4261 for (int i = _old_methods->length() - 1; i >= 0; i--) {
4262 Method* method = _old_methods->at(i);
4263 method->set_constants(scratch_class->constants());
4264 }
4265
4266 // NOTE: this doesn't work because you can redefine the same class in two
4267 // threads, each getting their own constant pool data appended to the
4268 // original constant pool. In order for the new methods to work when they
4269 // become old methods, they need to keep their updated copy of the constant pool.
4270
4271 {
4272 // walk all previous versions of the klass
4273 InstanceKlass *ik = the_class;
4274 PreviousVersionWalker pvw(ik);
4275 do {
4276 ik = pvw.next_previous_version();
4277 if (ik != nullptr) {
4278
4279 // attach previous version of klass to the new constant pool
4280 ik->set_constants(scratch_class->constants());
4281
4282 // Attach each method in the previous version of klass to the
4283 // new constant pool
4284 Array<Method*>* prev_methods = ik->methods();
4285 for (int i = prev_methods->length() - 1; i >= 0; i--) {
4286 Method* method = prev_methods->at(i);
4287 method->set_constants(scratch_class->constants());
4288 }
4289 }
4290 } while (ik != nullptr);
4291 }
4292 #endif
4293
4294 // Replace methods and constantpool
4295 the_class->set_methods(_new_methods);
4296 scratch_class->set_methods(_old_methods); // To prevent potential GCing of the old methods,
4297 // and to be able to undo operation easily.
4298
4299 Array<int>* old_ordering = the_class->method_ordering();
4300 the_class->set_method_ordering(scratch_class->method_ordering());
4301 scratch_class->set_method_ordering(old_ordering);
4302
4303 ConstantPool* old_constants = the_class->constants();
4304 the_class->set_constants(scratch_class->constants());
4305 scratch_class->set_constants(old_constants); // See the previous comment.
4306 #if 0
4307 // We are swapping the guts of "the new class" with the guts of "the
4308 // class". Since the old constant pool has just been attached to "the
4309 // new class", it seems logical to set the pool holder in the old
4310 // constant pool also. However, doing this will change the observable
4311 // class hierarchy for any old methods that are still executing. A
4312 // method can query the identity of its "holder" and this query uses
4313 // the method's constant pool link to find the holder. The change in
4314 // holding class from "the class" to "the new class" can confuse
4315 // things.
4316 //
4317 // Setting the old constant pool's holder will also cause
4318 // verification done during vtable initialization below to fail.
4319 // During vtable initialization, the vtable's class is verified to be
4320 // a subtype of the method's holder. The vtable's class is "the
4321 // class" and the method's holder is gotten from the constant pool
4322 // link in the method itself. For "the class"'s directly implemented
4323 // methods, the method holder is "the class" itself (as gotten from
4324 // the new constant pool). The check works fine in this case. The
4325 // check also works fine for methods inherited from super classes.
4326 //
4327 // Miranda methods are a little more complicated. A miranda method is
4328 // provided by an interface when the class implementing the interface
4329 // does not provide its own method. These interfaces are implemented
4330 // internally as an InstanceKlass. These special instanceKlasses
4331 // share the constant pool of the class that "implements" the
4332 // interface. By sharing the constant pool, the method holder of a
4333 // miranda method is the class that "implements" the interface. In a
4334 // non-redefine situation, the subtype check works fine. However, if
4335 // the old constant pool's pool holder is modified, then the check
4336 // fails because there is no class hierarchy relationship between the
4337 // vtable's class and "the new class".
4338
4339 old_constants->set_pool_holder(scratch_class());
4340 #endif
4341
4342 // track number of methods that are EMCP for add_previous_version() call below
4343 int emcp_method_count = check_methods_and_mark_as_obsolete();
4344 transfer_old_native_function_registrations(the_class);
4345
4346 if (scratch_class->get_cached_class_file() != the_class->get_cached_class_file()) {
4347 // 1. the_class doesn't have a cache yet, scratch_class does have a cache.
4348 // 2. The same class can be present twice in the scratch classes list or there
4349 // are multiple concurrent RetransformClasses calls on different threads.
4350 // the_class and scratch_class have the same cached bytes, but different buffers.
4351 // In such cases we need to deallocate one of the buffers.
4352 // 3. RedefineClasses and the_class has cached bytes from a previous transformation.
4353 // In the case we need to use class bytes from scratch_class.
4354 if (the_class->get_cached_class_file() != nullptr) {
4355 os::free(the_class->get_cached_class_file());
4356 }
4357 the_class->set_cached_class_file(scratch_class->get_cached_class_file());
4358 }
4359
4360 // null out in scratch class to not delete twice. The class to be redefined
4361 // always owns these bytes.
4362 scratch_class->set_cached_class_file(nullptr);
4363
4364 // Replace inner_classes
4365 Array<u2>* old_inner_classes = the_class->inner_classes();
4366 the_class->set_inner_classes(scratch_class->inner_classes());
4367 scratch_class->set_inner_classes(old_inner_classes);
4368
4369 // Initialize the vtable and interface table after
4370 // methods have been rewritten
4371 // no exception should happen here since we explicitly
4372 // do not check loader constraints.
4373 // compare_and_normalize_class_versions has already checked:
4374 // - classloaders unchanged, signatures unchanged
4375 // - all instanceKlasses for redefined classes reused & contents updated
4376 the_class->vtable().initialize_vtable();
4377 the_class->itable().initialize_itable();
4378
4379 // Leave arrays of jmethodIDs and itable index cache unchanged
4380
4381 // Copy the "source debug extension" attribute from new class version
4382 the_class->set_source_debug_extension(
4383 scratch_class->source_debug_extension(),
4384 scratch_class->source_debug_extension() == nullptr ? 0 :
4385 (int)strlen(scratch_class->source_debug_extension()));
4386
4387 // Use of javac -g could be different in the old and the new
4388 if (scratch_class->has_localvariable_table() !=
4389 the_class->has_localvariable_table()) {
4390 the_class->set_has_localvariable_table(scratch_class->has_localvariable_table());
4391 }
4392
4393 swap_annotations(the_class, scratch_class);
4394
4395 // Replace minor version number of class file
4396 u2 old_minor_version = the_class->constants()->minor_version();
4397 the_class->constants()->set_minor_version(scratch_class->constants()->minor_version());
4398 scratch_class->constants()->set_minor_version(old_minor_version);
4399
4400 // Replace major version number of class file
4401 u2 old_major_version = the_class->constants()->major_version();
4402 the_class->constants()->set_major_version(scratch_class->constants()->major_version());
4403 scratch_class->constants()->set_major_version(old_major_version);
4404
4405 // Replace CP indexes for class and name+type of enclosing method
4406 u2 old_class_idx = the_class->enclosing_method_class_index();
4407 u2 old_method_idx = the_class->enclosing_method_method_index();
4408 the_class->set_enclosing_method_indices(
4409 scratch_class->enclosing_method_class_index(),
4410 scratch_class->enclosing_method_method_index());
4411 scratch_class->set_enclosing_method_indices(old_class_idx, old_method_idx);
4412
4413 if (!the_class->has_been_redefined()) {
4414 the_class->set_has_been_redefined();
4415 }
4416
4417 // Scratch class is unloaded but still needs cleaning, and skipping for CDS.
4418 scratch_class->set_is_scratch_class();
4419
4420 // keep track of previous versions of this class
4421 the_class->add_previous_version(scratch_class, emcp_method_count);
4422
4423 _timer_rsc_phase1.stop();
4424 if (log_is_enabled(Info, redefine, class, timer)) {
4425 _timer_rsc_phase2.start();
4426 }
4427
4428 if (the_class->oop_map_cache() != nullptr) {
4429 // Flush references to any obsolete methods from the oop map cache
4430 // so that obsolete methods are not pinned.
4431 the_class->oop_map_cache()->flush_obsolete_entries();
4432 }
4433
4434 increment_class_counter(the_class);
4435
4436 if (EventClassRedefinition::is_enabled()) {
4437 EventClassRedefinition event;
4438 event.set_classModificationCount(java_lang_Class::classRedefinedCount(the_class->java_mirror()));
4439 event.set_redefinedClass(the_class);
4440 event.set_redefinitionId(_id);
4441 event.commit();
4442 }
4443
4444 {
4445 ResourceMark rm(current);
4446 // increment the classRedefinedCount field in the_class and in any
4447 // direct and indirect subclasses of the_class
4448 log_info(redefine, class, load)
4449 ("redefined name=%s, count=%d (avail_mem=" UINT64_FORMAT "K)",
4450 the_class->external_name(), java_lang_Class::classRedefinedCount(the_class->java_mirror()), os::available_memory() >> 10);
4451 Events::log_redefinition(current, "redefined class name=%s, count=%d",
4452 the_class->external_name(),
4453 java_lang_Class::classRedefinedCount(the_class->java_mirror()));
4454
4455 }
4456 _timer_rsc_phase2.stop();
4457
4458 } // end redefine_single_class()
4459
4460
4461 // Increment the classRedefinedCount field in the specific InstanceKlass
4462 // and in all direct and indirect subclasses.
4463 void VM_RedefineClasses::increment_class_counter(InstanceKlass* ik) {
4464 for (ClassHierarchyIterator iter(ik); !iter.done(); iter.next()) {
4465 // Only update instanceKlasses
4466 Klass* sub = iter.klass();
4467 if (sub->is_instance_klass()) {
4468 oop class_mirror = InstanceKlass::cast(sub)->java_mirror();
4469 Klass* class_oop = java_lang_Class::as_Klass(class_mirror);
4470 int new_count = java_lang_Class::classRedefinedCount(class_mirror) + 1;
4471 java_lang_Class::set_classRedefinedCount(class_mirror, new_count);
4472
4473 if (class_oop != _the_class) {
4474 // _the_class count is printed at end of redefine_single_class()
4475 log_debug(redefine, class, subclass)("updated count in subclass=%s to %d", ik->external_name(), new_count);
4476 }
4477 }
4478 }
4479 }
4480
4481 void VM_RedefineClasses::CheckClass::do_klass(Klass* k) {
4482 bool no_old_methods = true; // be optimistic
4483
4484 // Both array and instance classes have vtables.
4485 // a vtable should never contain old or obsolete methods
4486 ResourceMark rm(_thread);
4487 if (k->vtable_length() > 0 &&
4488 !k->vtable().check_no_old_or_obsolete_entries()) {
4489 if (log_is_enabled(Trace, redefine, class, obsolete, metadata)) {
4490 log_trace(redefine, class, obsolete, metadata)
4491 ("klassVtable::check_no_old_or_obsolete_entries failure -- OLD or OBSOLETE method found -- class: %s",
4492 k->signature_name());
4493 k->vtable().dump_vtable();
4494 }
4495 no_old_methods = false;
4496 }
4497
4498 if (k->is_instance_klass()) {
4499 HandleMark hm(_thread);
4500 InstanceKlass *ik = InstanceKlass::cast(k);
4501
4502 // an itable should never contain old or obsolete methods
4503 if (ik->itable_length() > 0 &&
4504 !ik->itable().check_no_old_or_obsolete_entries()) {
4505 if (log_is_enabled(Trace, redefine, class, obsolete, metadata)) {
4506 log_trace(redefine, class, obsolete, metadata)
4507 ("klassItable::check_no_old_or_obsolete_entries failure -- OLD or OBSOLETE method found -- class: %s",
4508 ik->signature_name());
4509 ik->itable().dump_itable();
4510 }
4511 no_old_methods = false;
4512 }
4513
4514 // the constant pool cache should never contain non-deleted old or obsolete methods
4515 if (ik->constants() != nullptr &&
4516 ik->constants()->cache() != nullptr &&
4517 !ik->constants()->cache()->check_no_old_or_obsolete_entries()) {
4518 if (log_is_enabled(Trace, redefine, class, obsolete, metadata)) {
4519 log_trace(redefine, class, obsolete, metadata)
4520 ("cp-cache::check_no_old_or_obsolete_entries failure -- OLD or OBSOLETE method found -- class: %s",
4521 ik->signature_name());
4522 ik->constants()->cache()->dump_cache();
4523 }
4524 no_old_methods = false;
4525 }
4526 }
4527
4528 // print and fail guarantee if old methods are found.
4529 if (!no_old_methods) {
4530 if (log_is_enabled(Trace, redefine, class, obsolete, metadata)) {
4531 dump_methods();
4532 } else {
4533 log_trace(redefine, class)("Use the '-Xlog:redefine+class*:' option "
4534 "to see more info about the following guarantee() failure.");
4535 }
4536 guarantee(false, "OLD and/or OBSOLETE method(s) found");
4537 }
4538 }
4539
4540 u8 VM_RedefineClasses::next_id() {
4541 while (true) {
4542 u8 id = _id_counter;
4543 u8 next_id = id + 1;
4544 u8 result = Atomic::cmpxchg(&_id_counter, id, next_id);
4545 if (result == id) {
4546 return next_id;
4547 }
4548 }
4549 }
4550
4551 void VM_RedefineClasses::dump_methods() {
4552 int j;
4553 log_trace(redefine, class, dump)("_old_methods --");
4554 for (j = 0; j < _old_methods->length(); ++j) {
4555 LogStreamHandle(Trace, redefine, class, dump) log_stream;
4556 Method* m = _old_methods->at(j);
4557 log_stream.print("%4d (%5d) ", j, m->vtable_index());
4558 m->access_flags().print_on(&log_stream);
4559 log_stream.print(" -- ");
4560 m->print_name(&log_stream);
4561 log_stream.cr();
4562 }
4563 log_trace(redefine, class, dump)("_new_methods --");
4564 for (j = 0; j < _new_methods->length(); ++j) {
4565 LogStreamHandle(Trace, redefine, class, dump) log_stream;
4566 Method* m = _new_methods->at(j);
4567 log_stream.print("%4d (%5d) ", j, m->vtable_index());
4568 m->access_flags().print_on(&log_stream);
4569 log_stream.print(" -- ");
4570 m->print_name(&log_stream);
4571 log_stream.cr();
4572 }
4573 log_trace(redefine, class, dump)("_matching_methods --");
4574 for (j = 0; j < _matching_methods_length; ++j) {
4575 LogStreamHandle(Trace, redefine, class, dump) log_stream;
4576 Method* m = _matching_old_methods[j];
4577 log_stream.print("%4d (%5d) ", j, m->vtable_index());
4578 m->access_flags().print_on(&log_stream);
4579 log_stream.print(" -- ");
4580 m->print_name();
4581 log_stream.cr();
4582
4583 m = _matching_new_methods[j];
4584 log_stream.print(" (%5d) ", m->vtable_index());
4585 m->access_flags().print_on(&log_stream);
4586 log_stream.cr();
4587 }
4588 log_trace(redefine, class, dump)("_deleted_methods --");
4589 for (j = 0; j < _deleted_methods_length; ++j) {
4590 LogStreamHandle(Trace, redefine, class, dump) log_stream;
4591 Method* m = _deleted_methods[j];
4592 log_stream.print("%4d (%5d) ", j, m->vtable_index());
4593 m->access_flags().print_on(&log_stream);
4594 log_stream.print(" -- ");
4595 m->print_name(&log_stream);
4596 log_stream.cr();
4597 }
4598 log_trace(redefine, class, dump)("_added_methods --");
4599 for (j = 0; j < _added_methods_length; ++j) {
4600 LogStreamHandle(Trace, redefine, class, dump) log_stream;
4601 Method* m = _added_methods[j];
4602 log_stream.print("%4d (%5d) ", j, m->vtable_index());
4603 m->access_flags().print_on(&log_stream);
4604 log_stream.print(" -- ");
4605 m->print_name(&log_stream);
4606 log_stream.cr();
4607 }
4608 }
4609
4610 void VM_RedefineClasses::print_on_error(outputStream* st) const {
4611 VM_Operation::print_on_error(st);
4612 if (_the_class != nullptr) {
4613 ResourceMark rm;
4614 st->print_cr(", redefining class %s", _the_class->external_name());
4615 }
4616 }