1 /*
2 * Copyright (c) 2003, 2024, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
24
25 #include "precompiled.hpp"
26 #include "cds/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/method.hpp"
52 #include "oops/oop.inline.hpp"
53 #include "oops/recordComponent.hpp"
54 #include "prims/jvmtiImpl.hpp"
55 #include "prims/jvmtiRedefineClasses.hpp"
56 #include "prims/jvmtiThreadState.inline.hpp"
57 #include "prims/resolvedMethodTable.hpp"
58 #include "prims/methodComparator.hpp"
59 #include "runtime/atomic.hpp"
60 #include "runtime/deoptimization.hpp"
61 #include "runtime/handles.inline.hpp"
62 #include "runtime/jniHandles.inline.hpp"
63 #include "runtime/relocator.hpp"
64 #include "runtime/safepointVerifiers.hpp"
65 #include "utilities/bitMap.inline.hpp"
66 #include "utilities/checkedCast.hpp"
67 #include "utilities/events.hpp"
68 #include "utilities/macros.hpp"
69
70 Array<Method*>* VM_RedefineClasses::_old_methods = nullptr;
71 Array<Method*>* VM_RedefineClasses::_new_methods = nullptr;
72 Method** VM_RedefineClasses::_matching_old_methods = nullptr;
73 Method** VM_RedefineClasses::_matching_new_methods = nullptr;
74 Method** VM_RedefineClasses::_deleted_methods = nullptr;
75 Method** VM_RedefineClasses::_added_methods = nullptr;
76 int VM_RedefineClasses::_matching_methods_length = 0;
77 int VM_RedefineClasses::_deleted_methods_length = 0;
78 int VM_RedefineClasses::_added_methods_length = 0;
79
80 // This flag is global as the constructor does not reset it:
81 bool VM_RedefineClasses::_has_redefined_Object = false;
82 u8 VM_RedefineClasses::_id_counter = 0;
83
84 VM_RedefineClasses::VM_RedefineClasses(jint class_count,
85 const jvmtiClassDefinition *class_defs,
86 JvmtiClassLoadKind class_load_kind) {
87 _class_count = class_count;
88 _class_defs = class_defs;
89 _class_load_kind = class_load_kind;
90 _any_class_has_resolved_methods = false;
91 _res = JVMTI_ERROR_NONE;
92 _the_class = nullptr;
93 _id = next_id();
94 }
95
96 static inline InstanceKlass* get_ik(jclass def) {
97 oop mirror = JNIHandles::resolve_non_null(def);
98 return InstanceKlass::cast(java_lang_Class::as_Klass(mirror));
99 }
100
101 // If any of the classes are being redefined, wait
102 // Parallel constant pool merging leads to indeterminate constant pools.
103 void VM_RedefineClasses::lock_classes() {
104 JvmtiThreadState *state = JvmtiThreadState::state_for(JavaThread::current());
105 GrowableArray<Klass*>* redef_classes = state->get_classes_being_redefined();
106
107 MonitorLocker ml(RedefineClasses_lock);
108
109 if (redef_classes == nullptr) {
110 redef_classes = new (mtClass) GrowableArray<Klass*>(1, mtClass);
111 state->set_classes_being_redefined(redef_classes);
112 }
113
114 bool has_redefined;
115 do {
116 has_redefined = false;
117 // Go through classes each time until none are being redefined. Skip
118 // the ones that are being redefined by this thread currently. Class file
119 // load hook event may trigger new class redefine when we are redefining
120 // a class (after lock_classes()).
121 for (int i = 0; i < _class_count; i++) {
122 InstanceKlass* ik = get_ik(_class_defs[i].klass);
123 // Check if we are currently redefining the class in this thread already.
124 if (redef_classes->contains(ik)) {
125 assert(ik->is_being_redefined(), "sanity");
126 } else {
127 if (ik->is_being_redefined()) {
128 ml.wait();
129 has_redefined = true;
130 break; // for loop
131 }
132 }
133 }
134 } while (has_redefined);
135
136 for (int i = 0; i < _class_count; i++) {
137 InstanceKlass* ik = get_ik(_class_defs[i].klass);
138 redef_classes->push(ik); // Add to the _classes_being_redefined list
139 ik->set_is_being_redefined(true);
140 }
141 ml.notify_all();
142 }
143
144 void VM_RedefineClasses::unlock_classes() {
145 JvmtiThreadState *state = JvmtiThreadState::state_for(JavaThread::current());
146 GrowableArray<Klass*>* redef_classes = state->get_classes_being_redefined();
147 assert(redef_classes != nullptr, "_classes_being_redefined is not allocated");
148
149 MonitorLocker ml(RedefineClasses_lock);
150
151 for (int i = _class_count - 1; i >= 0; i--) {
152 InstanceKlass* def_ik = get_ik(_class_defs[i].klass);
153 if (redef_classes->length() > 0) {
154 // Remove the class from _classes_being_redefined list
155 Klass* k = redef_classes->pop();
156 assert(def_ik == k, "unlocking wrong class");
157 }
158 assert(def_ik->is_being_redefined(),
159 "should be being redefined to get here");
160
161 // Unlock after we finish all redefines for this class within
162 // the thread. Same class can be pushed to the list multiple
163 // times (not more than once by each recursive redefinition).
164 if (!redef_classes->contains(def_ik)) {
165 def_ik->set_is_being_redefined(false);
166 }
167 }
168 ml.notify_all();
169 }
170
171 bool VM_RedefineClasses::doit_prologue() {
172 if (_class_count == 0) {
173 _res = JVMTI_ERROR_NONE;
174 return false;
175 }
176 if (_class_defs == nullptr) {
177 _res = JVMTI_ERROR_NULL_POINTER;
178 return false;
179 }
180
181 for (int i = 0; i < _class_count; i++) {
182 if (_class_defs[i].klass == nullptr) {
183 _res = JVMTI_ERROR_INVALID_CLASS;
184 return false;
185 }
186 if (_class_defs[i].class_byte_count == 0) {
187 _res = JVMTI_ERROR_INVALID_CLASS_FORMAT;
188 return false;
189 }
190 if (_class_defs[i].class_bytes == nullptr) {
191 _res = JVMTI_ERROR_NULL_POINTER;
192 return false;
193 }
194
195 oop mirror = JNIHandles::resolve_non_null(_class_defs[i].klass);
196 // classes for primitives, arrays, and hidden classes
197 // cannot be redefined.
198 if (!is_modifiable_class(mirror)) {
199 _res = JVMTI_ERROR_UNMODIFIABLE_CLASS;
200 return false;
201 }
202 }
203
204 // Start timer after all the sanity checks; not quite accurate, but
205 // better than adding a bunch of stop() calls.
206 if (log_is_enabled(Info, redefine, class, timer)) {
207 _timer_vm_op_prologue.start();
208 }
209
210 lock_classes();
211 // We first load new class versions in the prologue, because somewhere down the
212 // call chain it is required that the current thread is a Java thread.
213 _res = load_new_class_versions();
214 if (_res != JVMTI_ERROR_NONE) {
215 // free any successfully created classes, since none are redefined
216 for (int i = 0; i < _class_count; i++) {
217 if (_scratch_classes[i] != nullptr) {
218 ClassLoaderData* cld = _scratch_classes[i]->class_loader_data();
219 // Free the memory for this class at class unloading time. Not before
220 // because CMS might think this is still live.
221 InstanceKlass* ik = get_ik(_class_defs[i].klass);
222 if (ik->get_cached_class_file() == _scratch_classes[i]->get_cached_class_file()) {
223 // Don't double-free cached_class_file copied from the original class if error.
224 _scratch_classes[i]->set_cached_class_file(nullptr);
225 }
226 cld->add_to_deallocate_list(InstanceKlass::cast(_scratch_classes[i]));
227 }
228 }
229 // Free os::malloc allocated memory in load_new_class_version.
230 os::free(_scratch_classes);
231 _timer_vm_op_prologue.stop();
232 unlock_classes();
233 return false;
234 }
235
236 _timer_vm_op_prologue.stop();
237 return true;
238 }
239
240 void VM_RedefineClasses::doit() {
241 Thread* current = Thread::current();
242
243 if (log_is_enabled(Info, redefine, class, timer)) {
244 _timer_vm_op_doit.start();
245 }
246
247 #if INCLUDE_CDS
248 if (UseSharedSpaces) {
249 // Sharing is enabled so we remap the shared readonly space to
250 // shared readwrite, private just in case we need to redefine
251 // a shared class. We do the remap during the doit() phase of
252 // the safepoint to be safer.
253 if (!MetaspaceShared::remap_shared_readonly_as_readwrite()) {
254 log_info(redefine, class, load)("failed to remap shared readonly space to readwrite, private");
255 _res = JVMTI_ERROR_INTERNAL;
256 _timer_vm_op_doit.stop();
257 return;
258 }
259 }
260 #endif
261
262 // Mark methods seen on stack and everywhere else so old methods are not
263 // cleaned up if they're on the stack.
264 MetadataOnStackMark md_on_stack(/*walk_all_metadata*/true, /*redefinition_walk*/true);
265 HandleMark hm(current); // make sure any handles created are deleted
266 // before the stack walk again.
267
268 for (int i = 0; i < _class_count; i++) {
269 redefine_single_class(current, _class_defs[i].klass, _scratch_classes[i]);
270 }
271
272 // Flush all compiled code that depends on the classes redefined.
273 flush_dependent_code();
274
275 // Adjust constantpool caches and vtables for all classes
276 // that reference methods of the evolved classes.
277 // Have to do this after all classes are redefined and all methods that
278 // are redefined are marked as old.
279 AdjustAndCleanMetadata adjust_and_clean_metadata(current);
280 ClassLoaderDataGraph::classes_do(&adjust_and_clean_metadata);
281
282 // JSR-292 support
283 if (_any_class_has_resolved_methods) {
284 bool trace_name_printed = false;
285 ResolvedMethodTable::adjust_method_entries(&trace_name_printed);
286 }
287
288 // Increment flag indicating that some invariants are no longer true.
289 // See jvmtiExport.hpp for detailed explanation.
290 JvmtiExport::increment_redefinition_count();
291
292 // check_class() is optionally called for product bits, but is
293 // always called for non-product bits.
294 #ifdef PRODUCT
295 if (log_is_enabled(Trace, redefine, class, obsolete, metadata)) {
296 #endif
297 log_trace(redefine, class, obsolete, metadata)("calling check_class");
298 CheckClass check_class(current);
299 ClassLoaderDataGraph::classes_do(&check_class);
300 #ifdef PRODUCT
301 }
302 #endif
303
304 // Clean up any metadata now unreferenced while MetadataOnStackMark is set.
305 ClassLoaderDataGraph::clean_deallocate_lists(false);
306
307 _timer_vm_op_doit.stop();
308 }
309
310 void VM_RedefineClasses::doit_epilogue() {
311 unlock_classes();
312
313 // Free os::malloc allocated memory.
314 os::free(_scratch_classes);
315
316 // Reset the_class to null for error printing.
317 _the_class = nullptr;
318
319 if (log_is_enabled(Info, redefine, class, timer)) {
320 // Used to have separate timers for "doit" and "all", but the timer
321 // overhead skewed the measurements.
322 julong doit_time = _timer_vm_op_doit.milliseconds();
323 julong all_time = _timer_vm_op_prologue.milliseconds() + doit_time;
324
325 log_info(redefine, class, timer)
326 ("vm_op: all=" JULONG_FORMAT " prologue=" JULONG_FORMAT " doit=" JULONG_FORMAT,
327 all_time, (julong)_timer_vm_op_prologue.milliseconds(), doit_time);
328 log_info(redefine, class, timer)
329 ("redefine_single_class: phase1=" JULONG_FORMAT " phase2=" JULONG_FORMAT,
330 (julong)_timer_rsc_phase1.milliseconds(), (julong)_timer_rsc_phase2.milliseconds());
331 }
332 }
333
334 bool VM_RedefineClasses::is_modifiable_class(oop klass_mirror) {
335 // classes for primitives cannot be redefined
336 if (java_lang_Class::is_primitive(klass_mirror)) {
337 return false;
338 }
339 Klass* k = java_lang_Class::as_Klass(klass_mirror);
340 // classes for arrays cannot be redefined
341 if (k == nullptr || !k->is_instance_klass()) {
342 return false;
343 }
344
345 // Cannot redefine or retransform a hidden class.
346 if (InstanceKlass::cast(k)->is_hidden()) {
347 return false;
348 }
349 if (InstanceKlass::cast(k) == vmClasses::Continuation_klass()) {
350 // Don't redefine Continuation class. See 8302779.
351 return false;
352 }
353 return true;
354 }
355
356 // Append the current entry at scratch_i in scratch_cp to *merge_cp_p
357 // where the end of *merge_cp_p is specified by *merge_cp_length_p. For
358 // direct CP entries, there is just the current entry to append. For
359 // indirect and double-indirect CP entries, there are zero or more
360 // referenced CP entries along with the current entry to append.
361 // Indirect and double-indirect CP entries are handled by recursive
362 // calls to append_entry() as needed. The referenced CP entries are
363 // always appended to *merge_cp_p before the referee CP entry. These
364 // referenced CP entries may already exist in *merge_cp_p in which case
365 // there is nothing extra to append and only the current entry is
366 // appended.
367 void VM_RedefineClasses::append_entry(const constantPoolHandle& scratch_cp,
368 int scratch_i, constantPoolHandle *merge_cp_p, int *merge_cp_length_p) {
369
370 // append is different depending on entry tag type
371 switch (scratch_cp->tag_at(scratch_i).value()) {
372
373 // The old verifier is implemented outside the VM. It loads classes,
374 // but does not resolve constant pool entries directly so we never
375 // see Class entries here with the old verifier. Similarly the old
376 // verifier does not like Class entries in the input constant pool.
377 // The split-verifier is implemented in the VM so it can optionally
378 // and directly resolve constant pool entries to load classes. The
379 // split-verifier can accept either Class entries or UnresolvedClass
380 // entries in the input constant pool. We revert the appended copy
381 // back to UnresolvedClass so that either verifier will be happy
382 // with the constant pool entry.
383 //
384 // this is an indirect CP entry so it needs special handling
385 case JVM_CONSTANT_Class:
386 case JVM_CONSTANT_UnresolvedClass:
387 {
388 int name_i = scratch_cp->klass_name_index_at(scratch_i);
389 int new_name_i = find_or_append_indirect_entry(scratch_cp, name_i, merge_cp_p,
390 merge_cp_length_p);
391
392 if (new_name_i != name_i) {
393 log_trace(redefine, class, constantpool)
394 ("Class entry@%d name_index change: %d to %d",
395 *merge_cp_length_p, name_i, new_name_i);
396 }
397
398 (*merge_cp_p)->temp_unresolved_klass_at_put(*merge_cp_length_p, new_name_i);
399 if (scratch_i != *merge_cp_length_p) {
400 // The new entry in *merge_cp_p is at a different index than
401 // the new entry in scratch_cp so we need to map the index values.
402 map_index(scratch_cp, scratch_i, *merge_cp_length_p);
403 }
404 (*merge_cp_length_p)++;
405 } break;
406
407 // these are direct CP entries so they can be directly appended,
408 // but double and long take two constant pool entries
409 case JVM_CONSTANT_Double: // fall through
410 case JVM_CONSTANT_Long:
411 {
412 ConstantPool::copy_entry_to(scratch_cp, scratch_i, *merge_cp_p, *merge_cp_length_p);
413
414 if (scratch_i != *merge_cp_length_p) {
415 // The new entry in *merge_cp_p is at a different index than
416 // the new entry in scratch_cp so we need to map the index values.
417 map_index(scratch_cp, scratch_i, *merge_cp_length_p);
418 }
419 (*merge_cp_length_p) += 2;
420 } break;
421
422 // these are direct CP entries so they can be directly appended
423 case JVM_CONSTANT_Float: // fall through
424 case JVM_CONSTANT_Integer: // fall through
425 case JVM_CONSTANT_Utf8: // fall through
426
427 // This was an indirect CP entry, but it has been changed into
428 // Symbol*s so this entry can be directly appended.
429 case JVM_CONSTANT_String: // fall through
430 {
431 ConstantPool::copy_entry_to(scratch_cp, scratch_i, *merge_cp_p, *merge_cp_length_p);
432
433 if (scratch_i != *merge_cp_length_p) {
434 // The new entry in *merge_cp_p is at a different index than
435 // the new entry in scratch_cp so we need to map the index values.
436 map_index(scratch_cp, scratch_i, *merge_cp_length_p);
437 }
438 (*merge_cp_length_p)++;
439 } break;
440
441 // this is an indirect CP entry so it needs special handling
442 case JVM_CONSTANT_NameAndType:
443 {
444 int name_ref_i = scratch_cp->name_ref_index_at(scratch_i);
445 int new_name_ref_i = find_or_append_indirect_entry(scratch_cp, name_ref_i, merge_cp_p,
446 merge_cp_length_p);
447
448 int signature_ref_i = scratch_cp->signature_ref_index_at(scratch_i);
449 int new_signature_ref_i = find_or_append_indirect_entry(scratch_cp, signature_ref_i,
450 merge_cp_p, merge_cp_length_p);
451
452 // If the referenced entries already exist in *merge_cp_p, then
453 // both new_name_ref_i and new_signature_ref_i will both be 0.
454 // In that case, all we are appending is the current entry.
455 if (new_name_ref_i != name_ref_i) {
456 log_trace(redefine, class, constantpool)
457 ("NameAndType entry@%d name_ref_index change: %d to %d",
458 *merge_cp_length_p, name_ref_i, new_name_ref_i);
459 }
460 if (new_signature_ref_i != signature_ref_i) {
461 log_trace(redefine, class, constantpool)
462 ("NameAndType entry@%d signature_ref_index change: %d to %d",
463 *merge_cp_length_p, signature_ref_i, new_signature_ref_i);
464 }
465
466 (*merge_cp_p)->name_and_type_at_put(*merge_cp_length_p,
467 new_name_ref_i, new_signature_ref_i);
468 if (scratch_i != *merge_cp_length_p) {
469 // The new entry in *merge_cp_p is at a different index than
470 // the new entry in scratch_cp so we need to map the index values.
471 map_index(scratch_cp, scratch_i, *merge_cp_length_p);
472 }
473 (*merge_cp_length_p)++;
474 } break;
475
476 // this is a double-indirect CP entry so it needs special handling
477 case JVM_CONSTANT_Fieldref: // fall through
478 case JVM_CONSTANT_InterfaceMethodref: // fall through
479 case JVM_CONSTANT_Methodref:
480 {
481 int klass_ref_i = scratch_cp->uncached_klass_ref_index_at(scratch_i);
482 int new_klass_ref_i = find_or_append_indirect_entry(scratch_cp, klass_ref_i,
483 merge_cp_p, merge_cp_length_p);
484
485 int name_and_type_ref_i = scratch_cp->uncached_name_and_type_ref_index_at(scratch_i);
486 int new_name_and_type_ref_i = find_or_append_indirect_entry(scratch_cp, name_and_type_ref_i,
487 merge_cp_p, merge_cp_length_p);
488
489 const char *entry_name = nullptr;
490 switch (scratch_cp->tag_at(scratch_i).value()) {
491 case JVM_CONSTANT_Fieldref:
492 entry_name = "Fieldref";
493 (*merge_cp_p)->field_at_put(*merge_cp_length_p, new_klass_ref_i,
494 new_name_and_type_ref_i);
495 break;
496 case JVM_CONSTANT_InterfaceMethodref:
497 entry_name = "IFMethodref";
498 (*merge_cp_p)->interface_method_at_put(*merge_cp_length_p,
499 new_klass_ref_i, new_name_and_type_ref_i);
500 break;
501 case JVM_CONSTANT_Methodref:
502 entry_name = "Methodref";
503 (*merge_cp_p)->method_at_put(*merge_cp_length_p, new_klass_ref_i,
504 new_name_and_type_ref_i);
505 break;
506 default:
507 guarantee(false, "bad switch");
508 break;
509 }
510
511 if (klass_ref_i != new_klass_ref_i) {
512 log_trace(redefine, class, constantpool)
513 ("%s entry@%d class_index changed: %d to %d", entry_name, *merge_cp_length_p, klass_ref_i, new_klass_ref_i);
514 }
515 if (name_and_type_ref_i != new_name_and_type_ref_i) {
516 log_trace(redefine, class, constantpool)
517 ("%s entry@%d name_and_type_index changed: %d to %d",
518 entry_name, *merge_cp_length_p, name_and_type_ref_i, new_name_and_type_ref_i);
519 }
520
521 if (scratch_i != *merge_cp_length_p) {
522 // The new entry in *merge_cp_p is at a different index than
523 // the new entry in scratch_cp so we need to map the index values.
524 map_index(scratch_cp, scratch_i, *merge_cp_length_p);
525 }
526 (*merge_cp_length_p)++;
527 } break;
528
529 // this is an indirect CP entry so it needs special handling
530 case JVM_CONSTANT_MethodType:
531 {
532 int ref_i = scratch_cp->method_type_index_at(scratch_i);
533 int new_ref_i = find_or_append_indirect_entry(scratch_cp, ref_i, merge_cp_p,
534 merge_cp_length_p);
535 if (new_ref_i != ref_i) {
536 log_trace(redefine, class, constantpool)
537 ("MethodType entry@%d ref_index change: %d to %d", *merge_cp_length_p, ref_i, new_ref_i);
538 }
539 (*merge_cp_p)->method_type_index_at_put(*merge_cp_length_p, new_ref_i);
540 if (scratch_i != *merge_cp_length_p) {
541 // The new entry in *merge_cp_p is at a different index than
542 // the new entry in scratch_cp so we need to map the index values.
543 map_index(scratch_cp, scratch_i, *merge_cp_length_p);
544 }
545 (*merge_cp_length_p)++;
546 } break;
547
548 // this is an indirect CP entry so it needs special handling
549 case JVM_CONSTANT_MethodHandle:
550 {
551 int ref_kind = scratch_cp->method_handle_ref_kind_at(scratch_i);
552 int ref_i = scratch_cp->method_handle_index_at(scratch_i);
553 int new_ref_i = find_or_append_indirect_entry(scratch_cp, ref_i, merge_cp_p,
554 merge_cp_length_p);
555 if (new_ref_i != ref_i) {
556 log_trace(redefine, class, constantpool)
557 ("MethodHandle entry@%d ref_index change: %d to %d", *merge_cp_length_p, ref_i, new_ref_i);
558 }
559 (*merge_cp_p)->method_handle_index_at_put(*merge_cp_length_p, ref_kind, new_ref_i);
560 if (scratch_i != *merge_cp_length_p) {
561 // The new entry in *merge_cp_p is at a different index than
562 // the new entry in scratch_cp so we need to map the index values.
563 map_index(scratch_cp, scratch_i, *merge_cp_length_p);
564 }
565 (*merge_cp_length_p)++;
566 } break;
567
568 // this is an indirect CP entry so it needs special handling
569 case JVM_CONSTANT_Dynamic: // fall through
570 case JVM_CONSTANT_InvokeDynamic:
571 {
572 // Index of the bootstrap specifier in the operands array
573 int old_bs_i = scratch_cp->bootstrap_methods_attribute_index(scratch_i);
574 int new_bs_i = find_or_append_operand(scratch_cp, old_bs_i, merge_cp_p,
575 merge_cp_length_p);
576 // The bootstrap method NameAndType_info index
577 int old_ref_i = scratch_cp->bootstrap_name_and_type_ref_index_at(scratch_i);
578 int new_ref_i = find_or_append_indirect_entry(scratch_cp, old_ref_i, merge_cp_p,
579 merge_cp_length_p);
580 if (new_bs_i != old_bs_i) {
581 log_trace(redefine, class, constantpool)
582 ("Dynamic entry@%d bootstrap_method_attr_index change: %d to %d",
583 *merge_cp_length_p, old_bs_i, new_bs_i);
584 }
585 if (new_ref_i != old_ref_i) {
586 log_trace(redefine, class, constantpool)
587 ("Dynamic entry@%d name_and_type_index change: %d to %d", *merge_cp_length_p, old_ref_i, new_ref_i);
588 }
589
590 if (scratch_cp->tag_at(scratch_i).is_dynamic_constant())
591 (*merge_cp_p)->dynamic_constant_at_put(*merge_cp_length_p, new_bs_i, new_ref_i);
592 else
593 (*merge_cp_p)->invoke_dynamic_at_put(*merge_cp_length_p, new_bs_i, new_ref_i);
594 if (scratch_i != *merge_cp_length_p) {
595 // The new entry in *merge_cp_p is at a different index than
596 // the new entry in scratch_cp so we need to map the index values.
597 map_index(scratch_cp, scratch_i, *merge_cp_length_p);
598 }
599 (*merge_cp_length_p)++;
600 } break;
601
602 // At this stage, Class or UnresolvedClass could be in scratch_cp, but not
603 // ClassIndex
604 case JVM_CONSTANT_ClassIndex: // fall through
605
606 // Invalid is used as the tag for the second constant pool entry
607 // occupied by JVM_CONSTANT_Double or JVM_CONSTANT_Long. It should
608 // not be seen by itself.
609 case JVM_CONSTANT_Invalid: // fall through
610
611 // At this stage, String could be here, but not StringIndex
612 case JVM_CONSTANT_StringIndex: // fall through
613
614 // At this stage JVM_CONSTANT_UnresolvedClassInError should not be here
615 case JVM_CONSTANT_UnresolvedClassInError: // fall through
616
617 default:
618 {
619 // leave a breadcrumb
620 jbyte bad_value = scratch_cp->tag_at(scratch_i).value();
621 ShouldNotReachHere();
622 } break;
623 } // end switch tag value
624 } // end append_entry()
625
626
627 u2 VM_RedefineClasses::find_or_append_indirect_entry(const constantPoolHandle& scratch_cp,
628 int ref_i, constantPoolHandle *merge_cp_p, int *merge_cp_length_p) {
629
630 int new_ref_i = ref_i;
631 bool match = (ref_i < *merge_cp_length_p) &&
632 scratch_cp->compare_entry_to(ref_i, *merge_cp_p, ref_i);
633
634 if (!match) {
635 // forward reference in *merge_cp_p or not a direct match
636 int found_i = scratch_cp->find_matching_entry(ref_i, *merge_cp_p);
637 if (found_i != 0) {
638 guarantee(found_i != ref_i, "compare_entry_to() and find_matching_entry() do not agree");
639 // Found a matching entry somewhere else in *merge_cp_p so just need a mapping entry.
640 new_ref_i = found_i;
641 map_index(scratch_cp, ref_i, found_i);
642 } else {
643 // no match found so we have to append this entry to *merge_cp_p
644 append_entry(scratch_cp, ref_i, merge_cp_p, merge_cp_length_p);
645 // The above call to append_entry() can only append one entry
646 // so the post call query of *merge_cp_length_p is only for
647 // the sake of consistency.
648 new_ref_i = *merge_cp_length_p - 1;
649 }
650 }
651
652 // constant pool indices are u2, unless the merged constant pool overflows which
653 // we don't check for.
654 return checked_cast<u2>(new_ref_i);
655 } // end find_or_append_indirect_entry()
656
657
658 // Append a bootstrap specifier into the merge_cp operands that is semantically equal
659 // to the scratch_cp operands bootstrap specifier passed by the old_bs_i index.
660 // Recursively append new merge_cp entries referenced by the new bootstrap specifier.
661 void VM_RedefineClasses::append_operand(const constantPoolHandle& scratch_cp, int old_bs_i,
662 constantPoolHandle *merge_cp_p, int *merge_cp_length_p) {
663
664 u2 old_ref_i = scratch_cp->operand_bootstrap_method_ref_index_at(old_bs_i);
665 u2 new_ref_i = find_or_append_indirect_entry(scratch_cp, old_ref_i, merge_cp_p,
666 merge_cp_length_p);
667 if (new_ref_i != old_ref_i) {
668 log_trace(redefine, class, constantpool)
669 ("operands entry@%d bootstrap method ref_index change: %d to %d", _operands_cur_length, old_ref_i, new_ref_i);
670 }
671
672 Array<u2>* merge_ops = (*merge_cp_p)->operands();
673 int new_bs_i = _operands_cur_length;
674 // We have _operands_cur_length == 0 when the merge_cp operands is empty yet.
675 // However, the operand_offset_at(0) was set in the extend_operands() call.
676 int new_base = (new_bs_i == 0) ? (*merge_cp_p)->operand_offset_at(0)
677 : (*merge_cp_p)->operand_next_offset_at(new_bs_i - 1);
678 u2 argc = scratch_cp->operand_argument_count_at(old_bs_i);
679
680 ConstantPool::operand_offset_at_put(merge_ops, _operands_cur_length, new_base);
681 merge_ops->at_put(new_base++, new_ref_i);
682 merge_ops->at_put(new_base++, argc);
683
684 for (int i = 0; i < argc; i++) {
685 u2 old_arg_ref_i = scratch_cp->operand_argument_index_at(old_bs_i, i);
686 u2 new_arg_ref_i = find_or_append_indirect_entry(scratch_cp, old_arg_ref_i, merge_cp_p,
687 merge_cp_length_p);
688 merge_ops->at_put(new_base++, new_arg_ref_i);
689 if (new_arg_ref_i != old_arg_ref_i) {
690 log_trace(redefine, class, constantpool)
691 ("operands entry@%d bootstrap method argument ref_index change: %d to %d",
692 _operands_cur_length, old_arg_ref_i, new_arg_ref_i);
693 }
694 }
695 if (old_bs_i != _operands_cur_length) {
696 // The bootstrap specifier in *merge_cp_p is at a different index than
697 // that in scratch_cp so we need to map the index values.
698 map_operand_index(old_bs_i, new_bs_i);
699 }
700 _operands_cur_length++;
701 } // end append_operand()
702
703
704 int VM_RedefineClasses::find_or_append_operand(const constantPoolHandle& scratch_cp,
705 int old_bs_i, constantPoolHandle *merge_cp_p, int *merge_cp_length_p) {
706
707 int new_bs_i = old_bs_i; // bootstrap specifier index
708 bool match = (old_bs_i < _operands_cur_length) &&
709 scratch_cp->compare_operand_to(old_bs_i, *merge_cp_p, old_bs_i);
710
711 if (!match) {
712 // forward reference in *merge_cp_p or not a direct match
713 int found_i = scratch_cp->find_matching_operand(old_bs_i, *merge_cp_p,
714 _operands_cur_length);
715 if (found_i != -1) {
716 guarantee(found_i != old_bs_i, "compare_operand_to() and find_matching_operand() disagree");
717 // found a matching operand somewhere else in *merge_cp_p so just need a mapping
718 new_bs_i = found_i;
719 map_operand_index(old_bs_i, found_i);
720 } else {
721 // no match found so we have to append this bootstrap specifier to *merge_cp_p
722 append_operand(scratch_cp, old_bs_i, merge_cp_p, merge_cp_length_p);
723 new_bs_i = _operands_cur_length - 1;
724 }
725 }
726 return new_bs_i;
727 } // end find_or_append_operand()
728
729
730 void VM_RedefineClasses::finalize_operands_merge(const constantPoolHandle& merge_cp, TRAPS) {
731 if (merge_cp->operands() == nullptr) {
732 return;
733 }
734 // Shrink the merge_cp operands
735 merge_cp->shrink_operands(_operands_cur_length, CHECK);
736
737 if (log_is_enabled(Trace, redefine, class, constantpool)) {
738 // don't want to loop unless we are tracing
739 int count = 0;
740 for (int i = 1; i < _operands_index_map_p->length(); i++) {
741 int value = _operands_index_map_p->at(i);
742 if (value != -1) {
743 log_trace(redefine, class, constantpool)("operands_index_map[%d]: old=%d new=%d", count, i, value);
744 count++;
745 }
746 }
747 }
748 // Clean-up
749 _operands_index_map_p = nullptr;
750 _operands_cur_length = 0;
751 _operands_index_map_count = 0;
752 } // end finalize_operands_merge()
753
754 // Symbol* comparator for qsort
755 // The caller must have an active ResourceMark.
756 static int symcmp(const void* a, const void* b) {
757 char* astr = (*(Symbol**)a)->as_C_string();
758 char* bstr = (*(Symbol**)b)->as_C_string();
759 return strcmp(astr, bstr);
760 }
761
762 // The caller must have an active ResourceMark.
763 static jvmtiError check_attribute_arrays(const char* attr_name,
764 InstanceKlass* the_class, InstanceKlass* scratch_class,
765 Array<u2>* the_array, Array<u2>* scr_array) {
766 bool the_array_exists = the_array != Universe::the_empty_short_array();
767 bool scr_array_exists = scr_array != Universe::the_empty_short_array();
768
769 int array_len = the_array->length();
770 if (the_array_exists && scr_array_exists) {
771 if (array_len != scr_array->length()) {
772 log_trace(redefine, class)
773 ("redefined class %s attribute change error: %s len=%d changed to len=%d",
774 the_class->external_name(), attr_name, array_len, scr_array->length());
775 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_CLASS_ATTRIBUTE_CHANGED;
776 }
777
778 // The order of entries in the attribute array is not specified so we
779 // have to explicitly check for the same contents. We do this by copying
780 // the referenced symbols into their own arrays, sorting them and then
781 // comparing each element pair.
782
783 Symbol** the_syms = NEW_RESOURCE_ARRAY_RETURN_NULL(Symbol*, array_len);
784 Symbol** scr_syms = NEW_RESOURCE_ARRAY_RETURN_NULL(Symbol*, array_len);
785
786 if (the_syms == nullptr || scr_syms == nullptr) {
787 return JVMTI_ERROR_OUT_OF_MEMORY;
788 }
789
790 for (int i = 0; i < array_len; i++) {
791 int the_cp_index = the_array->at(i);
792 int scr_cp_index = scr_array->at(i);
793 the_syms[i] = the_class->constants()->klass_name_at(the_cp_index);
794 scr_syms[i] = scratch_class->constants()->klass_name_at(scr_cp_index);
795 }
796
797 qsort(the_syms, array_len, sizeof(Symbol*), symcmp);
798 qsort(scr_syms, array_len, sizeof(Symbol*), symcmp);
799
800 for (int i = 0; i < array_len; i++) {
801 if (the_syms[i] != scr_syms[i]) {
802 log_info(redefine, class)
803 ("redefined class %s attribute change error: %s[%d]: %s changed to %s",
804 the_class->external_name(), attr_name, i,
805 the_syms[i]->as_C_string(), scr_syms[i]->as_C_string());
806 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_CLASS_ATTRIBUTE_CHANGED;
807 }
808 }
809 } else if (the_array_exists ^ scr_array_exists) {
810 const char* action_str = (the_array_exists) ? "removed" : "added";
811 log_info(redefine, class)
812 ("redefined class %s attribute change error: %s attribute %s",
813 the_class->external_name(), attr_name, action_str);
814 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_CLASS_ATTRIBUTE_CHANGED;
815 }
816 return JVMTI_ERROR_NONE;
817 }
818
819 static jvmtiError check_nest_attributes(InstanceKlass* the_class,
820 InstanceKlass* scratch_class) {
821 // Check whether the class NestHost attribute has been changed.
822 Thread* thread = Thread::current();
823 ResourceMark rm(thread);
824 u2 the_nest_host_idx = the_class->nest_host_index();
825 u2 scr_nest_host_idx = scratch_class->nest_host_index();
826
827 if (the_nest_host_idx != 0 && scr_nest_host_idx != 0) {
828 Symbol* the_sym = the_class->constants()->klass_name_at(the_nest_host_idx);
829 Symbol* scr_sym = scratch_class->constants()->klass_name_at(scr_nest_host_idx);
830 if (the_sym != scr_sym) {
831 log_info(redefine, class, nestmates)
832 ("redefined class %s attribute change error: NestHost class: %s replaced with: %s",
833 the_class->external_name(), the_sym->as_C_string(), scr_sym->as_C_string());
834 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_CLASS_ATTRIBUTE_CHANGED;
835 }
836 } else if ((the_nest_host_idx == 0) ^ (scr_nest_host_idx == 0)) {
837 const char* action_str = (the_nest_host_idx != 0) ? "removed" : "added";
838 log_info(redefine, class, nestmates)
839 ("redefined class %s attribute change error: NestHost attribute %s",
840 the_class->external_name(), action_str);
841 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_CLASS_ATTRIBUTE_CHANGED;
842 }
843
844 // Check whether the class NestMembers attribute has been changed.
845 return check_attribute_arrays("NestMembers",
846 the_class, scratch_class,
847 the_class->nest_members(),
848 scratch_class->nest_members());
849 }
850
851 // Return an error status if the class Record attribute was changed.
852 static jvmtiError check_record_attribute(InstanceKlass* the_class, InstanceKlass* scratch_class) {
853 // Get lists of record components.
854 Array<RecordComponent*>* the_record = the_class->record_components();
855 Array<RecordComponent*>* scr_record = scratch_class->record_components();
856 bool the_record_exists = the_record != nullptr;
857 bool scr_record_exists = scr_record != nullptr;
858
859 if (the_record_exists && scr_record_exists) {
860 int the_num_components = the_record->length();
861 int scr_num_components = scr_record->length();
862 if (the_num_components != scr_num_components) {
863 log_info(redefine, class, record)
864 ("redefined class %s attribute change error: Record num_components=%d changed to num_components=%d",
865 the_class->external_name(), the_num_components, scr_num_components);
866 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_CLASS_ATTRIBUTE_CHANGED;
867 }
868
869 // Compare each field in each record component.
870 ConstantPool* the_cp = the_class->constants();
871 ConstantPool* scr_cp = scratch_class->constants();
872 for (int x = 0; x < the_num_components; x++) {
873 RecordComponent* the_component = the_record->at(x);
874 RecordComponent* scr_component = scr_record->at(x);
875 const Symbol* const the_name = the_cp->symbol_at(the_component->name_index());
876 const Symbol* const scr_name = scr_cp->symbol_at(scr_component->name_index());
877 const Symbol* const the_descr = the_cp->symbol_at(the_component->descriptor_index());
878 const Symbol* const scr_descr = scr_cp->symbol_at(scr_component->descriptor_index());
879 if (the_name != scr_name || the_descr != scr_descr) {
880 log_info(redefine, class, record)
881 ("redefined class %s attribute change error: Record name_index, descriptor_index, and/or attributes_count changed",
882 the_class->external_name());
883 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_CLASS_ATTRIBUTE_CHANGED;
884 }
885
886 int the_gen_sig = the_component->generic_signature_index();
887 int scr_gen_sig = scr_component->generic_signature_index();
888 const Symbol* const the_gen_sig_sym = (the_gen_sig == 0 ? nullptr :
889 the_cp->symbol_at(the_component->generic_signature_index()));
890 const Symbol* const scr_gen_sig_sym = (scr_gen_sig == 0 ? nullptr :
891 scr_cp->symbol_at(scr_component->generic_signature_index()));
892 if (the_gen_sig_sym != scr_gen_sig_sym) {
893 log_info(redefine, class, record)
894 ("redefined class %s attribute change error: Record generic_signature attribute changed",
895 the_class->external_name());
896 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_CLASS_ATTRIBUTE_CHANGED;
897 }
898
899 // It's okay if a record component's annotations were changed.
900 }
901
902 } else if (the_record_exists ^ scr_record_exists) {
903 const char* action_str = (the_record_exists) ? "removed" : "added";
904 log_info(redefine, class, record)
905 ("redefined class %s attribute change error: Record attribute %s",
906 the_class->external_name(), action_str);
907 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_CLASS_ATTRIBUTE_CHANGED;
908 }
909
910 return JVMTI_ERROR_NONE;
911 }
912
913
914 static jvmtiError check_permitted_subclasses_attribute(InstanceKlass* the_class,
915 InstanceKlass* scratch_class) {
916 Thread* thread = Thread::current();
917 ResourceMark rm(thread);
918
919 // Check whether the class PermittedSubclasses attribute has been changed.
920 return check_attribute_arrays("PermittedSubclasses",
921 the_class, scratch_class,
922 the_class->permitted_subclasses(),
923 scratch_class->permitted_subclasses());
924 }
925
926 static bool can_add_or_delete(Method* m) {
927 // Compatibility mode
928 return (AllowRedefinitionToAddDeleteMethods &&
929 (m->is_private() && (m->is_static() || m->is_final())));
930 }
931
932 jvmtiError VM_RedefineClasses::compare_and_normalize_class_versions(
933 InstanceKlass* the_class,
934 InstanceKlass* scratch_class) {
935 int i;
936
937 // Check superclasses, or rather their names, since superclasses themselves can be
938 // requested to replace.
939 // Check for null superclass first since this might be java.lang.Object
940 if (the_class->super() != scratch_class->super() &&
941 (the_class->super() == nullptr || scratch_class->super() == nullptr ||
942 the_class->super()->name() !=
943 scratch_class->super()->name())) {
944 log_info(redefine, class, normalize)
945 ("redefined class %s superclass change error: superclass changed from %s to %s.",
946 the_class->external_name(),
947 the_class->super() == nullptr ? "null" : the_class->super()->external_name(),
948 scratch_class->super() == nullptr ? "null" : scratch_class->super()->external_name());
949 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_HIERARCHY_CHANGED;
950 }
951
952 // Check if the number, names and order of directly implemented interfaces are the same.
953 // I think in principle we should just check if the sets of names of directly implemented
954 // interfaces are the same, i.e. the order of declaration (which, however, if changed in the
955 // .java file, also changes in .class file) should not matter. However, comparing sets is
956 // technically a bit more difficult, and, more importantly, I am not sure at present that the
957 // order of interfaces does not matter on the implementation level, i.e. that the VM does not
958 // rely on it somewhere.
959 Array<InstanceKlass*>* k_interfaces = the_class->local_interfaces();
960 Array<InstanceKlass*>* k_new_interfaces = scratch_class->local_interfaces();
961 int n_intfs = k_interfaces->length();
962 if (n_intfs != k_new_interfaces->length()) {
963 log_info(redefine, class, normalize)
964 ("redefined class %s interfaces change error: number of implemented interfaces changed from %d to %d.",
965 the_class->external_name(), n_intfs, k_new_interfaces->length());
966 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_HIERARCHY_CHANGED;
967 }
968 for (i = 0; i < n_intfs; i++) {
969 if (k_interfaces->at(i)->name() !=
970 k_new_interfaces->at(i)->name()) {
971 log_info(redefine, class, normalize)
972 ("redefined class %s interfaces change error: interface changed from %s to %s.",
973 the_class->external_name(),
974 k_interfaces->at(i)->external_name(), k_new_interfaces->at(i)->external_name());
975 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_HIERARCHY_CHANGED;
976 }
977 }
978
979 // Check whether class is in the error init state.
980 if (the_class->is_in_error_state()) {
981 log_info(redefine, class, normalize)
982 ("redefined class %s is in error init state.", the_class->external_name());
983 // TBD #5057930: special error code is needed in 1.6
984 return JVMTI_ERROR_INVALID_CLASS;
985 }
986
987 // Check whether the nest-related attributes have been changed.
988 jvmtiError err = check_nest_attributes(the_class, scratch_class);
989 if (err != JVMTI_ERROR_NONE) {
990 return err;
991 }
992
993 // Check whether the Record attribute has been changed.
994 err = check_record_attribute(the_class, scratch_class);
995 if (err != JVMTI_ERROR_NONE) {
996 return err;
997 }
998
999 // Check whether the PermittedSubclasses attribute has been changed.
1000 err = check_permitted_subclasses_attribute(the_class, scratch_class);
1001 if (err != JVMTI_ERROR_NONE) {
1002 return err;
1003 }
1004
1005 // Check whether class modifiers are the same.
1006 jushort old_flags = (jushort) the_class->access_flags().get_flags();
1007 jushort new_flags = (jushort) scratch_class->access_flags().get_flags();
1008 if (old_flags != new_flags) {
1009 log_info(redefine, class, normalize)
1010 ("redefined class %s modifiers change error: modifiers changed from %d to %d.",
1011 the_class->external_name(), old_flags, new_flags);
1012 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_CLASS_MODIFIERS_CHANGED;
1013 }
1014
1015 // Check if the number, names, types and order of fields declared in these classes
1016 // are the same.
1017 JavaFieldStream old_fs(the_class);
1018 JavaFieldStream new_fs(scratch_class);
1019 for (; !old_fs.done() && !new_fs.done(); old_fs.next(), new_fs.next()) {
1020 // name and signature
1021 Symbol* name_sym1 = the_class->constants()->symbol_at(old_fs.name_index());
1022 Symbol* sig_sym1 = the_class->constants()->symbol_at(old_fs.signature_index());
1023 Symbol* name_sym2 = scratch_class->constants()->symbol_at(new_fs.name_index());
1024 Symbol* sig_sym2 = scratch_class->constants()->symbol_at(new_fs.signature_index());
1025 if (name_sym1 != name_sym2 || sig_sym1 != sig_sym2) {
1026 log_info(redefine, class, normalize)
1027 ("redefined class %s fields change error: field %s %s changed to %s %s.",
1028 the_class->external_name(),
1029 sig_sym1->as_C_string(), name_sym1->as_C_string(),
1030 sig_sym2->as_C_string(), name_sym2->as_C_string());
1031 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_SCHEMA_CHANGED;
1032 }
1033 // offset
1034 if (old_fs.offset() != new_fs.offset()) {
1035 log_info(redefine, class, normalize)
1036 ("redefined class %s field %s change error: offset changed from %d to %d.",
1037 the_class->external_name(), name_sym2->as_C_string(), old_fs.offset(), new_fs.offset());
1038 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_SCHEMA_CHANGED;
1039 }
1040 // access
1041 old_flags = old_fs.access_flags().as_short();
1042 new_flags = new_fs.access_flags().as_short();
1043 if ((old_flags ^ new_flags) & JVM_RECOGNIZED_FIELD_MODIFIERS) {
1044 log_info(redefine, class, normalize)
1045 ("redefined class %s field %s change error: modifiers changed from %d to %d.",
1046 the_class->external_name(), name_sym2->as_C_string(), old_flags, new_flags);
1047 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_SCHEMA_CHANGED;
1048 }
1049 }
1050
1051 // If both streams aren't done then we have a differing number of
1052 // fields.
1053 if (!old_fs.done() || !new_fs.done()) {
1054 const char* action = old_fs.done() ? "added" : "deleted";
1055 log_info(redefine, class, normalize)
1056 ("redefined class %s fields change error: some fields were %s.",
1057 the_class->external_name(), action);
1058 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_SCHEMA_CHANGED;
1059 }
1060
1061 // Do a parallel walk through the old and new methods. Detect
1062 // cases where they match (exist in both), have been added in
1063 // the new methods, or have been deleted (exist only in the
1064 // old methods). The class file parser places methods in order
1065 // by method name, but does not order overloaded methods by
1066 // signature. In order to determine what fate befell the methods,
1067 // this code places the overloaded new methods that have matching
1068 // old methods in the same order as the old methods and places
1069 // new overloaded methods at the end of overloaded methods of
1070 // that name. The code for this order normalization is adapted
1071 // from the algorithm used in InstanceKlass::find_method().
1072 // Since we are swapping out of order entries as we find them,
1073 // we only have to search forward through the overloaded methods.
1074 // Methods which are added and have the same name as an existing
1075 // method (but different signature) will be put at the end of
1076 // the methods with that name, and the name mismatch code will
1077 // handle them.
1078 Array<Method*>* k_old_methods(the_class->methods());
1079 Array<Method*>* k_new_methods(scratch_class->methods());
1080 int n_old_methods = k_old_methods->length();
1081 int n_new_methods = k_new_methods->length();
1082 Thread* thread = Thread::current();
1083
1084 int ni = 0;
1085 int oi = 0;
1086 while (true) {
1087 Method* k_old_method;
1088 Method* k_new_method;
1089 enum { matched, added, deleted, undetermined } method_was = undetermined;
1090
1091 if (oi >= n_old_methods) {
1092 if (ni >= n_new_methods) {
1093 break; // we've looked at everything, done
1094 }
1095 // New method at the end
1096 k_new_method = k_new_methods->at(ni);
1097 method_was = added;
1098 } else if (ni >= n_new_methods) {
1099 // Old method, at the end, is deleted
1100 k_old_method = k_old_methods->at(oi);
1101 method_was = deleted;
1102 } else {
1103 // There are more methods in both the old and new lists
1104 k_old_method = k_old_methods->at(oi);
1105 k_new_method = k_new_methods->at(ni);
1106 if (k_old_method->name() != k_new_method->name()) {
1107 // Methods are sorted by method name, so a mismatch means added
1108 // or deleted
1109 if (k_old_method->name()->fast_compare(k_new_method->name()) > 0) {
1110 method_was = added;
1111 } else {
1112 method_was = deleted;
1113 }
1114 } else if (k_old_method->signature() == k_new_method->signature()) {
1115 // Both the name and signature match
1116 method_was = matched;
1117 } else {
1118 // The name matches, but the signature doesn't, which means we have to
1119 // search forward through the new overloaded methods.
1120 int nj; // outside the loop for post-loop check
1121 for (nj = ni + 1; nj < n_new_methods; nj++) {
1122 Method* m = k_new_methods->at(nj);
1123 if (k_old_method->name() != m->name()) {
1124 // reached another method name so no more overloaded methods
1125 method_was = deleted;
1126 break;
1127 }
1128 if (k_old_method->signature() == m->signature()) {
1129 // found a match so swap the methods
1130 k_new_methods->at_put(ni, m);
1131 k_new_methods->at_put(nj, k_new_method);
1132 k_new_method = m;
1133 method_was = matched;
1134 break;
1135 }
1136 }
1137
1138 if (nj >= n_new_methods) {
1139 // reached the end without a match; so method was deleted
1140 method_was = deleted;
1141 }
1142 }
1143 }
1144
1145 switch (method_was) {
1146 case matched:
1147 // methods match, be sure modifiers do too
1148 old_flags = (jushort) k_old_method->access_flags().get_flags();
1149 new_flags = (jushort) k_new_method->access_flags().get_flags();
1150 if ((old_flags ^ new_flags) & ~(JVM_ACC_NATIVE)) {
1151 log_info(redefine, class, normalize)
1152 ("redefined class %s method %s modifiers error: modifiers changed from %d to %d",
1153 the_class->external_name(), k_old_method->name_and_sig_as_C_string(), old_flags, new_flags);
1154 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_METHOD_MODIFIERS_CHANGED;
1155 }
1156 {
1157 u2 new_num = k_new_method->method_idnum();
1158 u2 old_num = k_old_method->method_idnum();
1159 if (new_num != old_num) {
1160 Method* idnum_owner = scratch_class->method_with_idnum(old_num);
1161 if (idnum_owner != nullptr) {
1162 // There is already a method assigned this idnum -- switch them
1163 // Take current and original idnum from the new_method
1164 idnum_owner->set_method_idnum(new_num);
1165 idnum_owner->set_orig_method_idnum(k_new_method->orig_method_idnum());
1166 }
1167 // Take current and original idnum from the old_method
1168 k_new_method->set_method_idnum(old_num);
1169 k_new_method->set_orig_method_idnum(k_old_method->orig_method_idnum());
1170 if (thread->has_pending_exception()) {
1171 return JVMTI_ERROR_OUT_OF_MEMORY;
1172 }
1173 }
1174 }
1175 JFR_ONLY(k_new_method->copy_trace_flags(*k_old_method->trace_flags_addr());)
1176 log_trace(redefine, class, normalize)
1177 ("Method matched: new: %s [%d] == old: %s [%d]",
1178 k_new_method->name_and_sig_as_C_string(), ni, k_old_method->name_and_sig_as_C_string(), oi);
1179 // advance to next pair of methods
1180 ++oi;
1181 ++ni;
1182 break;
1183 case added:
1184 // method added, see if it is OK
1185 if (!can_add_or_delete(k_new_method)) {
1186 log_info(redefine, class, normalize)
1187 ("redefined class %s methods error: added method: %s [%d]",
1188 the_class->external_name(), k_new_method->name_and_sig_as_C_string(), ni);
1189 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_METHOD_ADDED;
1190 }
1191 {
1192 u2 num = the_class->next_method_idnum();
1193 if (num == ConstMethod::UNSET_IDNUM) {
1194 // cannot add any more methods
1195 log_info(redefine, class, normalize)
1196 ("redefined class %s methods error: can't create ID for new method %s [%d]",
1197 the_class->external_name(), k_new_method->name_and_sig_as_C_string(), ni);
1198 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_METHOD_ADDED;
1199 }
1200 u2 new_num = k_new_method->method_idnum();
1201 Method* idnum_owner = scratch_class->method_with_idnum(num);
1202 if (idnum_owner != nullptr) {
1203 // There is already a method assigned this idnum -- switch them
1204 // Take current and original idnum from the new_method
1205 idnum_owner->set_method_idnum(new_num);
1206 idnum_owner->set_orig_method_idnum(k_new_method->orig_method_idnum());
1207 }
1208 k_new_method->set_method_idnum(num);
1209 k_new_method->set_orig_method_idnum(num);
1210 if (thread->has_pending_exception()) {
1211 return JVMTI_ERROR_OUT_OF_MEMORY;
1212 }
1213 }
1214 log_trace(redefine, class, normalize)
1215 ("Method added: new: %s [%d]", k_new_method->name_and_sig_as_C_string(), ni);
1216 ++ni; // advance to next new method
1217 break;
1218 case deleted:
1219 // method deleted, see if it is OK
1220 if (!can_add_or_delete(k_old_method)) {
1221 log_info(redefine, class, normalize)
1222 ("redefined class %s methods error: deleted method %s [%d]",
1223 the_class->external_name(), k_old_method->name_and_sig_as_C_string(), oi);
1224 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_METHOD_DELETED;
1225 }
1226 log_trace(redefine, class, normalize)
1227 ("Method deleted: old: %s [%d]", k_old_method->name_and_sig_as_C_string(), oi);
1228 ++oi; // advance to next old method
1229 break;
1230 default:
1231 ShouldNotReachHere();
1232 }
1233 }
1234
1235 return JVMTI_ERROR_NONE;
1236 }
1237
1238
1239 // Find new constant pool index value for old constant pool index value
1240 // by searching the index map. Returns zero (0) if there is no mapped
1241 // value for the old constant pool index.
1242 u2 VM_RedefineClasses::find_new_index(int old_index) {
1243 if (_index_map_count == 0) {
1244 // map is empty so nothing can be found
1245 return 0;
1246 }
1247
1248 if (old_index < 1 || old_index >= _index_map_p->length()) {
1249 // The old_index is out of range so it is not mapped. This should
1250 // not happen in regular constant pool merging use, but it can
1251 // happen if a corrupt annotation is processed.
1252 return 0;
1253 }
1254
1255 int value = _index_map_p->at(old_index);
1256 if (value == -1) {
1257 // the old_index is not mapped
1258 return 0;
1259 }
1260
1261 // constant pool indices are u2, unless the merged constant pool overflows which
1262 // we don't check for.
1263 return checked_cast<u2>(value);
1264 } // end find_new_index()
1265
1266
1267 // Find new bootstrap specifier index value for old bootstrap specifier index
1268 // value by searching the index map. Returns unused index (-1) if there is
1269 // no mapped value for the old bootstrap specifier index.
1270 int VM_RedefineClasses::find_new_operand_index(int old_index) {
1271 if (_operands_index_map_count == 0) {
1272 // map is empty so nothing can be found
1273 return -1;
1274 }
1275
1276 if (old_index == -1 || old_index >= _operands_index_map_p->length()) {
1277 // The old_index is out of range so it is not mapped.
1278 // This should not happen in regular constant pool merging use.
1279 return -1;
1280 }
1281
1282 int value = _operands_index_map_p->at(old_index);
1283 if (value == -1) {
1284 // the old_index is not mapped
1285 return -1;
1286 }
1287
1288 return value;
1289 } // end find_new_operand_index()
1290
1291
1292 // The bug 6214132 caused the verification to fail.
1293 // 1. What's done in RedefineClasses() before verification:
1294 // a) A reference to the class being redefined (_the_class) and a
1295 // reference to new version of the class (_scratch_class) are
1296 // saved here for use during the bytecode verification phase of
1297 // RedefineClasses.
1298 // b) The _java_mirror field from _the_class is copied to the
1299 // _java_mirror field in _scratch_class. This means that a jclass
1300 // returned for _the_class or _scratch_class will refer to the
1301 // same Java mirror. The verifier will see the "one true mirror"
1302 // for the class being verified.
1303 // 2. See comments in JvmtiThreadState for what is done during verification.
1304
1305 class RedefineVerifyMark : public StackObj {
1306 private:
1307 JvmtiThreadState* _state;
1308 Klass* _scratch_class;
1309 OopHandle _scratch_mirror;
1310
1311 public:
1312
1313 RedefineVerifyMark(Klass* the_class, Klass* scratch_class,
1314 JvmtiThreadState* state) : _state(state), _scratch_class(scratch_class)
1315 {
1316 _state->set_class_versions_map(the_class, scratch_class);
1317 _scratch_mirror = the_class->java_mirror_handle(); // this is a copy that is swapped
1318 _scratch_class->swap_java_mirror_handle(_scratch_mirror);
1319 }
1320
1321 ~RedefineVerifyMark() {
1322 // Restore the scratch class's mirror, so when scratch_class is removed
1323 // the correct mirror pointing to it can be cleared.
1324 _scratch_class->swap_java_mirror_handle(_scratch_mirror);
1325 _state->clear_class_versions_map();
1326 }
1327 };
1328
1329
1330 jvmtiError VM_RedefineClasses::load_new_class_versions() {
1331
1332 // For consistency allocate memory using os::malloc wrapper.
1333 _scratch_classes = (InstanceKlass**)
1334 os::malloc(sizeof(InstanceKlass*) * _class_count, mtClass);
1335 if (_scratch_classes == nullptr) {
1336 return JVMTI_ERROR_OUT_OF_MEMORY;
1337 }
1338 // Zero initialize the _scratch_classes array.
1339 for (int i = 0; i < _class_count; i++) {
1340 _scratch_classes[i] = nullptr;
1341 }
1342
1343 JavaThread* current = JavaThread::current();
1344 ResourceMark rm(current);
1345
1346 JvmtiThreadState *state = JvmtiThreadState::state_for(current);
1347 // state can only be null if the current thread is exiting which
1348 // should not happen since we're trying to do a RedefineClasses
1349 guarantee(state != nullptr, "exiting thread calling load_new_class_versions");
1350 for (int i = 0; i < _class_count; i++) {
1351 // Create HandleMark so that any handles created while loading new class
1352 // versions are deleted. Constant pools are deallocated while merging
1353 // constant pools
1354 HandleMark hm(current);
1355 InstanceKlass* the_class = get_ik(_class_defs[i].klass);
1356
1357 log_debug(redefine, class, load)
1358 ("loading name=%s kind=%d (avail_mem=" UINT64_FORMAT "K)",
1359 the_class->external_name(), _class_load_kind, os::available_memory() >> 10);
1360
1361 ClassFileStream st((u1*)_class_defs[i].class_bytes,
1362 _class_defs[i].class_byte_count,
1363 "__VM_RedefineClasses__",
1364 ClassFileStream::verify);
1365
1366 // Set redefined class handle in JvmtiThreadState class.
1367 // This redefined class is sent to agent event handler for class file
1368 // load hook event.
1369 state->set_class_being_redefined(the_class, _class_load_kind);
1370
1371 JavaThread* THREAD = current; // For exception macros.
1372 ExceptionMark em(THREAD);
1373 Handle protection_domain(THREAD, the_class->protection_domain());
1374 ClassLoadInfo cl_info(protection_domain);
1375 // Parse and create a class from the bytes, but this class isn't added
1376 // to the dictionary, so do not call resolve_from_stream.
1377 InstanceKlass* scratch_class = KlassFactory::create_from_stream(&st,
1378 the_class->name(),
1379 the_class->class_loader_data(),
1380 cl_info,
1381 THREAD);
1382
1383 // Clear class_being_redefined just to be sure.
1384 state->clear_class_being_redefined();
1385
1386 // TODO: if this is retransform, and nothing changed we can skip it
1387
1388 // Need to clean up allocated InstanceKlass if there's an error so assign
1389 // the result here. Caller deallocates all the scratch classes in case of
1390 // an error.
1391 _scratch_classes[i] = scratch_class;
1392
1393 if (HAS_PENDING_EXCEPTION) {
1394 Symbol* ex_name = PENDING_EXCEPTION->klass()->name();
1395 log_info(redefine, class, load, exceptions)("create_from_stream exception: '%s'", ex_name->as_C_string());
1396 CLEAR_PENDING_EXCEPTION;
1397
1398 if (ex_name == vmSymbols::java_lang_UnsupportedClassVersionError()) {
1399 return JVMTI_ERROR_UNSUPPORTED_VERSION;
1400 } else if (ex_name == vmSymbols::java_lang_ClassFormatError()) {
1401 return JVMTI_ERROR_INVALID_CLASS_FORMAT;
1402 } else if (ex_name == vmSymbols::java_lang_ClassCircularityError()) {
1403 return JVMTI_ERROR_CIRCULAR_CLASS_DEFINITION;
1404 } else if (ex_name == vmSymbols::java_lang_NoClassDefFoundError()) {
1405 // The message will be "XXX (wrong name: YYY)"
1406 return JVMTI_ERROR_NAMES_DONT_MATCH;
1407 } else if (ex_name == vmSymbols::java_lang_OutOfMemoryError()) {
1408 return JVMTI_ERROR_OUT_OF_MEMORY;
1409 } else { // Just in case more exceptions can be thrown..
1410 return JVMTI_ERROR_FAILS_VERIFICATION;
1411 }
1412 }
1413
1414 // Ensure class is linked before redefine
1415 if (!the_class->is_linked()) {
1416 the_class->link_class(THREAD);
1417 if (HAS_PENDING_EXCEPTION) {
1418 Symbol* ex_name = PENDING_EXCEPTION->klass()->name();
1419 oop message = java_lang_Throwable::message(PENDING_EXCEPTION);
1420 if (message != nullptr) {
1421 char* ex_msg = java_lang_String::as_utf8_string(message);
1422 log_info(redefine, class, load, exceptions)("link_class exception: '%s %s'",
1423 ex_name->as_C_string(), ex_msg);
1424 } else {
1425 log_info(redefine, class, load, exceptions)("link_class exception: '%s'",
1426 ex_name->as_C_string());
1427 }
1428 CLEAR_PENDING_EXCEPTION;
1429 if (ex_name == vmSymbols::java_lang_OutOfMemoryError()) {
1430 return JVMTI_ERROR_OUT_OF_MEMORY;
1431 } else if (ex_name == vmSymbols::java_lang_NoClassDefFoundError()) {
1432 return JVMTI_ERROR_INVALID_CLASS;
1433 } else {
1434 return JVMTI_ERROR_INTERNAL;
1435 }
1436 }
1437 }
1438
1439 // Do the validity checks in compare_and_normalize_class_versions()
1440 // before verifying the byte codes. By doing these checks first, we
1441 // limit the number of functions that require redirection from
1442 // the_class to scratch_class. In particular, we don't have to
1443 // modify JNI GetSuperclass() and thus won't change its performance.
1444 jvmtiError res = compare_and_normalize_class_versions(the_class,
1445 scratch_class);
1446 if (res != JVMTI_ERROR_NONE) {
1447 return res;
1448 }
1449
1450 // verify what the caller passed us
1451 {
1452 // The bug 6214132 caused the verification to fail.
1453 // Information about the_class and scratch_class is temporarily
1454 // recorded into jvmtiThreadState. This data is used to redirect
1455 // the_class to scratch_class in the JVM_* functions called by the
1456 // verifier. Please, refer to jvmtiThreadState.hpp for the detailed
1457 // description.
1458 RedefineVerifyMark rvm(the_class, scratch_class, state);
1459 Verifier::verify(scratch_class, true, THREAD);
1460 }
1461
1462 if (HAS_PENDING_EXCEPTION) {
1463 Symbol* ex_name = PENDING_EXCEPTION->klass()->name();
1464 log_info(redefine, class, load, exceptions)("verify_byte_codes exception: '%s'", ex_name->as_C_string());
1465 CLEAR_PENDING_EXCEPTION;
1466 if (ex_name == vmSymbols::java_lang_OutOfMemoryError()) {
1467 return JVMTI_ERROR_OUT_OF_MEMORY;
1468 } else {
1469 // tell the caller the bytecodes are bad
1470 return JVMTI_ERROR_FAILS_VERIFICATION;
1471 }
1472 }
1473
1474 res = merge_cp_and_rewrite(the_class, scratch_class, THREAD);
1475 if (HAS_PENDING_EXCEPTION) {
1476 Symbol* ex_name = PENDING_EXCEPTION->klass()->name();
1477 log_info(redefine, class, load, exceptions)("merge_cp_and_rewrite exception: '%s'", ex_name->as_C_string());
1478 CLEAR_PENDING_EXCEPTION;
1479 if (ex_name == vmSymbols::java_lang_OutOfMemoryError()) {
1480 return JVMTI_ERROR_OUT_OF_MEMORY;
1481 } else {
1482 return JVMTI_ERROR_INTERNAL;
1483 }
1484 }
1485
1486 #ifdef ASSERT
1487 {
1488 // verify what we have done during constant pool merging
1489 {
1490 RedefineVerifyMark rvm(the_class, scratch_class, state);
1491 Verifier::verify(scratch_class, true, THREAD);
1492 }
1493
1494 if (HAS_PENDING_EXCEPTION) {
1495 Symbol* ex_name = PENDING_EXCEPTION->klass()->name();
1496 log_info(redefine, class, load, exceptions)
1497 ("verify_byte_codes post merge-CP exception: '%s'", ex_name->as_C_string());
1498 CLEAR_PENDING_EXCEPTION;
1499 if (ex_name == vmSymbols::java_lang_OutOfMemoryError()) {
1500 return JVMTI_ERROR_OUT_OF_MEMORY;
1501 } else {
1502 // tell the caller that constant pool merging screwed up
1503 return JVMTI_ERROR_INTERNAL;
1504 }
1505 }
1506 }
1507 #endif // ASSERT
1508
1509 Rewriter::rewrite(scratch_class, THREAD);
1510 if (!HAS_PENDING_EXCEPTION) {
1511 scratch_class->link_methods(THREAD);
1512 }
1513 if (HAS_PENDING_EXCEPTION) {
1514 Symbol* ex_name = PENDING_EXCEPTION->klass()->name();
1515 log_info(redefine, class, load, exceptions)
1516 ("Rewriter::rewrite or link_methods exception: '%s'", ex_name->as_C_string());
1517 CLEAR_PENDING_EXCEPTION;
1518 if (ex_name == vmSymbols::java_lang_OutOfMemoryError()) {
1519 return JVMTI_ERROR_OUT_OF_MEMORY;
1520 } else {
1521 return JVMTI_ERROR_INTERNAL;
1522 }
1523 }
1524
1525 log_debug(redefine, class, load)
1526 ("loaded name=%s (avail_mem=" UINT64_FORMAT "K)", the_class->external_name(), os::available_memory() >> 10);
1527 }
1528
1529 return JVMTI_ERROR_NONE;
1530 }
1531
1532
1533 // Map old_index to new_index as needed. scratch_cp is only needed
1534 // for log calls.
1535 void VM_RedefineClasses::map_index(const constantPoolHandle& scratch_cp,
1536 int old_index, int new_index) {
1537 if (find_new_index(old_index) != 0) {
1538 // old_index is already mapped
1539 return;
1540 }
1541
1542 if (old_index == new_index) {
1543 // no mapping is needed
1544 return;
1545 }
1546
1547 _index_map_p->at_put(old_index, new_index);
1548 _index_map_count++;
1549
1550 log_trace(redefine, class, constantpool)
1551 ("mapped tag %d at index %d to %d", scratch_cp->tag_at(old_index).value(), old_index, new_index);
1552 } // end map_index()
1553
1554
1555 // Map old_index to new_index as needed.
1556 void VM_RedefineClasses::map_operand_index(int old_index, int new_index) {
1557 if (find_new_operand_index(old_index) != -1) {
1558 // old_index is already mapped
1559 return;
1560 }
1561
1562 if (old_index == new_index) {
1563 // no mapping is needed
1564 return;
1565 }
1566
1567 _operands_index_map_p->at_put(old_index, new_index);
1568 _operands_index_map_count++;
1569
1570 log_trace(redefine, class, constantpool)("mapped bootstrap specifier at index %d to %d", old_index, new_index);
1571 } // end map_index()
1572
1573
1574 // Merge old_cp and scratch_cp and return the results of the merge via
1575 // merge_cp_p. The number of entries in *merge_cp_p is returned via
1576 // merge_cp_length_p. The entries in old_cp occupy the same locations
1577 // in *merge_cp_p. Also creates a map of indices from entries in
1578 // scratch_cp to the corresponding entry in *merge_cp_p. Index map
1579 // entries are only created for entries in scratch_cp that occupy a
1580 // different location in *merged_cp_p.
1581 bool VM_RedefineClasses::merge_constant_pools(const constantPoolHandle& old_cp,
1582 const constantPoolHandle& scratch_cp, constantPoolHandle *merge_cp_p,
1583 int *merge_cp_length_p, TRAPS) {
1584
1585 if (merge_cp_p == nullptr) {
1586 assert(false, "caller must provide scratch constantPool");
1587 return false; // robustness
1588 }
1589 if (merge_cp_length_p == nullptr) {
1590 assert(false, "caller must provide scratch CP length");
1591 return false; // robustness
1592 }
1593 // Worst case we need old_cp->length() + scratch_cp()->length(),
1594 // but the caller might be smart so make sure we have at least
1595 // the minimum.
1596 if ((*merge_cp_p)->length() < old_cp->length()) {
1597 assert(false, "merge area too small");
1598 return false; // robustness
1599 }
1600
1601 log_info(redefine, class, constantpool)("old_cp_len=%d, scratch_cp_len=%d", old_cp->length(), scratch_cp->length());
1602
1603 {
1604 // Pass 0:
1605 // The old_cp is copied to *merge_cp_p; this means that any code
1606 // using old_cp does not have to change. This work looks like a
1607 // perfect fit for ConstantPool*::copy_cp_to(), but we need to
1608 // handle one special case:
1609 // - revert JVM_CONSTANT_Class to JVM_CONSTANT_UnresolvedClass
1610 // This will make verification happy.
1611
1612 int old_i; // index into old_cp
1613
1614 // index zero (0) is not used in constantPools
1615 for (old_i = 1; old_i < old_cp->length(); old_i++) {
1616 // leave debugging crumb
1617 jbyte old_tag = old_cp->tag_at(old_i).value();
1618 switch (old_tag) {
1619 case JVM_CONSTANT_Class:
1620 case JVM_CONSTANT_UnresolvedClass:
1621 // revert the copy to JVM_CONSTANT_UnresolvedClass
1622 // May be resolving while calling this so do the same for
1623 // JVM_CONSTANT_UnresolvedClass (klass_name_at() deals with transition)
1624 (*merge_cp_p)->temp_unresolved_klass_at_put(old_i,
1625 old_cp->klass_name_index_at(old_i));
1626 break;
1627
1628 case JVM_CONSTANT_Double:
1629 case JVM_CONSTANT_Long:
1630 // just copy the entry to *merge_cp_p, but double and long take
1631 // two constant pool entries
1632 ConstantPool::copy_entry_to(old_cp, old_i, *merge_cp_p, old_i);
1633 old_i++;
1634 break;
1635
1636 default:
1637 // just copy the entry to *merge_cp_p
1638 ConstantPool::copy_entry_to(old_cp, old_i, *merge_cp_p, old_i);
1639 break;
1640 }
1641 } // end for each old_cp entry
1642
1643 ConstantPool::copy_operands(old_cp, *merge_cp_p, CHECK_false);
1644 (*merge_cp_p)->extend_operands(scratch_cp, CHECK_false);
1645
1646 // We don't need to sanity check that *merge_cp_length_p is within
1647 // *merge_cp_p bounds since we have the minimum on-entry check above.
1648 (*merge_cp_length_p) = old_i;
1649 }
1650
1651 // merge_cp_len should be the same as old_cp->length() at this point
1652 // so this trace message is really a "warm-and-breathing" message.
1653 log_debug(redefine, class, constantpool)("after pass 0: merge_cp_len=%d", *merge_cp_length_p);
1654
1655 int scratch_i; // index into scratch_cp
1656 {
1657 // Pass 1a:
1658 // Compare scratch_cp entries to the old_cp entries that we have
1659 // already copied to *merge_cp_p. In this pass, we are eliminating
1660 // exact duplicates (matching entry at same index) so we only
1661 // compare entries in the common indice range.
1662 int increment = 1;
1663 int pass1a_length = MIN2(old_cp->length(), scratch_cp->length());
1664 for (scratch_i = 1; scratch_i < pass1a_length; scratch_i += increment) {
1665 switch (scratch_cp->tag_at(scratch_i).value()) {
1666 case JVM_CONSTANT_Double:
1667 case JVM_CONSTANT_Long:
1668 // double and long take two constant pool entries
1669 increment = 2;
1670 break;
1671
1672 default:
1673 increment = 1;
1674 break;
1675 }
1676
1677 bool match = scratch_cp->compare_entry_to(scratch_i, *merge_cp_p, scratch_i);
1678 if (match) {
1679 // found a match at the same index so nothing more to do
1680 continue;
1681 }
1682
1683 int found_i = scratch_cp->find_matching_entry(scratch_i, *merge_cp_p);
1684 if (found_i != 0) {
1685 guarantee(found_i != scratch_i,
1686 "compare_entry_to() and find_matching_entry() do not agree");
1687
1688 // Found a matching entry somewhere else in *merge_cp_p so
1689 // just need a mapping entry.
1690 map_index(scratch_cp, scratch_i, found_i);
1691 continue;
1692 }
1693
1694 // No match found so we have to append this entry and any unique
1695 // referenced entries to *merge_cp_p.
1696 append_entry(scratch_cp, scratch_i, merge_cp_p, merge_cp_length_p);
1697 }
1698 }
1699
1700 log_debug(redefine, class, constantpool)
1701 ("after pass 1a: merge_cp_len=%d, scratch_i=%d, index_map_len=%d",
1702 *merge_cp_length_p, scratch_i, _index_map_count);
1703
1704 if (scratch_i < scratch_cp->length()) {
1705 // Pass 1b:
1706 // old_cp is smaller than scratch_cp so there are entries in
1707 // scratch_cp that we have not yet processed. We take care of
1708 // those now.
1709 int increment = 1;
1710 for (; scratch_i < scratch_cp->length(); scratch_i += increment) {
1711 switch (scratch_cp->tag_at(scratch_i).value()) {
1712 case JVM_CONSTANT_Double:
1713 case JVM_CONSTANT_Long:
1714 // double and long take two constant pool entries
1715 increment = 2;
1716 break;
1717
1718 default:
1719 increment = 1;
1720 break;
1721 }
1722
1723 int found_i =
1724 scratch_cp->find_matching_entry(scratch_i, *merge_cp_p);
1725 if (found_i != 0) {
1726 // Found a matching entry somewhere else in *merge_cp_p so
1727 // just need a mapping entry.
1728 map_index(scratch_cp, scratch_i, found_i);
1729 continue;
1730 }
1731
1732 // No match found so we have to append this entry and any unique
1733 // referenced entries to *merge_cp_p.
1734 append_entry(scratch_cp, scratch_i, merge_cp_p, merge_cp_length_p);
1735 }
1736
1737 log_debug(redefine, class, constantpool)
1738 ("after pass 1b: merge_cp_len=%d, scratch_i=%d, index_map_len=%d",
1739 *merge_cp_length_p, scratch_i, _index_map_count);
1740 }
1741 finalize_operands_merge(*merge_cp_p, CHECK_false);
1742
1743 return true;
1744 } // end merge_constant_pools()
1745
1746
1747 // Scoped object to clean up the constant pool(s) created for merging
1748 class MergeCPCleaner {
1749 ClassLoaderData* _loader_data;
1750 ConstantPool* _cp;
1751 ConstantPool* _scratch_cp;
1752 public:
1753 MergeCPCleaner(ClassLoaderData* loader_data, ConstantPool* merge_cp) :
1754 _loader_data(loader_data), _cp(merge_cp), _scratch_cp(nullptr) {}
1755 ~MergeCPCleaner() {
1756 _loader_data->add_to_deallocate_list(_cp);
1757 if (_scratch_cp != nullptr) {
1758 _loader_data->add_to_deallocate_list(_scratch_cp);
1759 }
1760 }
1761 void add_scratch_cp(ConstantPool* scratch_cp) { _scratch_cp = scratch_cp; }
1762 };
1763
1764 // Merge constant pools between the_class and scratch_class and
1765 // potentially rewrite bytecodes in scratch_class to use the merged
1766 // constant pool.
1767 jvmtiError VM_RedefineClasses::merge_cp_and_rewrite(
1768 InstanceKlass* the_class, InstanceKlass* scratch_class,
1769 TRAPS) {
1770 // worst case merged constant pool length is old and new combined
1771 int merge_cp_length = the_class->constants()->length()
1772 + scratch_class->constants()->length();
1773
1774 // Constant pools are not easily reused so we allocate a new one
1775 // each time.
1776 // merge_cp is created unsafe for concurrent GC processing. It
1777 // should be marked safe before discarding it. Even though
1778 // garbage, if it crosses a card boundary, it may be scanned
1779 // in order to find the start of the first complete object on the card.
1780 ClassLoaderData* loader_data = the_class->class_loader_data();
1781 ConstantPool* merge_cp_oop =
1782 ConstantPool::allocate(loader_data,
1783 merge_cp_length,
1784 CHECK_(JVMTI_ERROR_OUT_OF_MEMORY));
1785 MergeCPCleaner cp_cleaner(loader_data, merge_cp_oop);
1786
1787 HandleMark hm(THREAD); // make sure handles are cleared before
1788 // MergeCPCleaner clears out merge_cp_oop
1789 constantPoolHandle merge_cp(THREAD, merge_cp_oop);
1790
1791 // Get constants() from the old class because it could have been rewritten
1792 // while we were at a safepoint allocating a new constant pool.
1793 constantPoolHandle old_cp(THREAD, the_class->constants());
1794 constantPoolHandle scratch_cp(THREAD, scratch_class->constants());
1795
1796 // If the length changed, the class was redefined out from under us. Return
1797 // an error.
1798 if (merge_cp_length != the_class->constants()->length()
1799 + scratch_class->constants()->length()) {
1800 return JVMTI_ERROR_INTERNAL;
1801 }
1802
1803 // Update the version number of the constant pools (may keep scratch_cp)
1804 merge_cp->increment_and_save_version(old_cp->version());
1805 scratch_cp->increment_and_save_version(old_cp->version());
1806
1807 ResourceMark rm(THREAD);
1808 _index_map_count = 0;
1809 _index_map_p = new intArray(scratch_cp->length(), scratch_cp->length(), -1);
1810
1811 _operands_cur_length = ConstantPool::operand_array_length(old_cp->operands());
1812 _operands_index_map_count = 0;
1813 int operands_index_map_len = ConstantPool::operand_array_length(scratch_cp->operands());
1814 _operands_index_map_p = new intArray(operands_index_map_len, operands_index_map_len, -1);
1815
1816 // reference to the cp holder is needed for copy_operands()
1817 merge_cp->set_pool_holder(scratch_class);
1818 bool result = merge_constant_pools(old_cp, scratch_cp, &merge_cp,
1819 &merge_cp_length, THREAD);
1820 merge_cp->set_pool_holder(nullptr);
1821
1822 if (!result) {
1823 // The merge can fail due to memory allocation failure or due
1824 // to robustness checks.
1825 return JVMTI_ERROR_INTERNAL;
1826 }
1827
1828 // ensure merged constant pool size does not overflow u2
1829 if (merge_cp_length > 0xFFFF) {
1830 log_warning(redefine, class, constantpool)("Merged constant pool overflow: %d entries", merge_cp_length);
1831 return JVMTI_ERROR_INTERNAL;
1832 }
1833
1834 // Set dynamic constants attribute from the original CP.
1835 if (old_cp->has_dynamic_constant()) {
1836 scratch_cp->set_has_dynamic_constant();
1837 }
1838
1839 log_info(redefine, class, constantpool)("merge_cp_len=%d, index_map_len=%d", merge_cp_length, _index_map_count);
1840
1841 if (_index_map_count == 0) {
1842 // there is nothing to map between the new and merged constant pools
1843
1844 // Copy attributes from scratch_cp to merge_cp
1845 merge_cp->copy_fields(scratch_cp());
1846
1847 if (old_cp->length() == scratch_cp->length()) {
1848 // The old and new constant pools are the same length and the
1849 // index map is empty. This means that the three constant pools
1850 // are equivalent (but not the same). Unfortunately, the new
1851 // constant pool has not gone through link resolution nor have
1852 // the new class bytecodes gone through constant pool cache
1853 // rewriting so we can't use the old constant pool with the new
1854 // class.
1855
1856 // toss the merged constant pool at return
1857 } else if (old_cp->length() < scratch_cp->length()) {
1858 // The old constant pool has fewer entries than the new constant
1859 // pool and the index map is empty. This means the new constant
1860 // pool is a superset of the old constant pool. However, the old
1861 // class bytecodes have already gone through constant pool cache
1862 // rewriting so we can't use the new constant pool with the old
1863 // class.
1864
1865 // toss the merged constant pool at return
1866 } else {
1867 // The old constant pool has more entries than the new constant
1868 // pool and the index map is empty. This means that both the old
1869 // and merged constant pools are supersets of the new constant
1870 // pool.
1871
1872 // Replace the new constant pool with a shrunken copy of the
1873 // merged constant pool
1874 set_new_constant_pool(loader_data, scratch_class, merge_cp, merge_cp_length,
1875 CHECK_(JVMTI_ERROR_OUT_OF_MEMORY));
1876 // The new constant pool replaces scratch_cp so have cleaner clean it up.
1877 // It can't be cleaned up while there are handles to it.
1878 cp_cleaner.add_scratch_cp(scratch_cp());
1879 }
1880 } else {
1881 if (log_is_enabled(Trace, redefine, class, constantpool)) {
1882 // don't want to loop unless we are tracing
1883 int count = 0;
1884 for (int i = 1; i < _index_map_p->length(); i++) {
1885 int value = _index_map_p->at(i);
1886
1887 if (value != -1) {
1888 log_trace(redefine, class, constantpool)("index_map[%d]: old=%d new=%d", count, i, value);
1889 count++;
1890 }
1891 }
1892 }
1893
1894 // We have entries mapped between the new and merged constant pools
1895 // so we have to rewrite some constant pool references.
1896 if (!rewrite_cp_refs(scratch_class)) {
1897 return JVMTI_ERROR_INTERNAL;
1898 }
1899
1900 // Copy attributes from scratch_cp to merge_cp (should be done after rewrite_cp_refs())
1901 merge_cp->copy_fields(scratch_cp());
1902
1903 // Replace the new constant pool with a shrunken copy of the
1904 // merged constant pool so now the rewritten bytecodes have
1905 // valid references; the previous new constant pool will get
1906 // GCed.
1907 set_new_constant_pool(loader_data, scratch_class, merge_cp, merge_cp_length,
1908 CHECK_(JVMTI_ERROR_OUT_OF_MEMORY));
1909 // The new constant pool replaces scratch_cp so have cleaner clean it up.
1910 // It can't be cleaned up while there are handles to it.
1911 cp_cleaner.add_scratch_cp(scratch_cp());
1912 }
1913
1914 return JVMTI_ERROR_NONE;
1915 } // end merge_cp_and_rewrite()
1916
1917
1918 // Rewrite constant pool references in klass scratch_class.
1919 bool VM_RedefineClasses::rewrite_cp_refs(InstanceKlass* scratch_class) {
1920
1921 // rewrite constant pool references in the nest attributes:
1922 if (!rewrite_cp_refs_in_nest_attributes(scratch_class)) {
1923 // propagate failure back to caller
1924 return false;
1925 }
1926
1927 // rewrite constant pool references in the Record attribute:
1928 if (!rewrite_cp_refs_in_record_attribute(scratch_class)) {
1929 // propagate failure back to caller
1930 return false;
1931 }
1932
1933 // rewrite constant pool references in the PermittedSubclasses attribute:
1934 if (!rewrite_cp_refs_in_permitted_subclasses_attribute(scratch_class)) {
1935 // propagate failure back to caller
1936 return false;
1937 }
1938
1939 // rewrite constant pool references in the LoadableDescriptors attribute:
1940 if (!rewrite_cp_refs_in_loadable_descriptors_attribute(scratch_class)) {
1941 // propagate failure back to caller
1942 return false;
1943 }
1944
1945 // rewrite constant pool references in the methods:
1946 if (!rewrite_cp_refs_in_methods(scratch_class)) {
1947 // propagate failure back to caller
1948 return false;
1949 }
1950
1951 // rewrite constant pool references in the class_annotations:
1952 if (!rewrite_cp_refs_in_class_annotations(scratch_class)) {
1953 // propagate failure back to caller
1954 return false;
1955 }
1956
1957 // rewrite constant pool references in the fields_annotations:
1958 if (!rewrite_cp_refs_in_fields_annotations(scratch_class)) {
1959 // propagate failure back to caller
1960 return false;
1961 }
1962
1963 // rewrite constant pool references in the methods_annotations:
1964 if (!rewrite_cp_refs_in_methods_annotations(scratch_class)) {
1965 // propagate failure back to caller
1966 return false;
1967 }
1968
1969 // rewrite constant pool references in the methods_parameter_annotations:
1970 if (!rewrite_cp_refs_in_methods_parameter_annotations(scratch_class)) {
1971 // propagate failure back to caller
1972 return false;
1973 }
1974
1975 // rewrite constant pool references in the methods_default_annotations:
1976 if (!rewrite_cp_refs_in_methods_default_annotations(scratch_class)) {
1977 // propagate failure back to caller
1978 return false;
1979 }
1980
1981 // rewrite constant pool references in the class_type_annotations:
1982 if (!rewrite_cp_refs_in_class_type_annotations(scratch_class)) {
1983 // propagate failure back to caller
1984 return false;
1985 }
1986
1987 // rewrite constant pool references in the fields_type_annotations:
1988 if (!rewrite_cp_refs_in_fields_type_annotations(scratch_class)) {
1989 // propagate failure back to caller
1990 return false;
1991 }
1992
1993 // rewrite constant pool references in the methods_type_annotations:
1994 if (!rewrite_cp_refs_in_methods_type_annotations(scratch_class)) {
1995 // propagate failure back to caller
1996 return false;
1997 }
1998
1999 // There can be type annotations in the Code part of a method_info attribute.
2000 // These annotations are not accessible, even by reflection.
2001 // Currently they are not even parsed by the ClassFileParser.
2002 // If runtime access is added they will also need to be rewritten.
2003
2004 // rewrite source file name index:
2005 u2 source_file_name_idx = scratch_class->source_file_name_index();
2006 if (source_file_name_idx != 0) {
2007 u2 new_source_file_name_idx = find_new_index(source_file_name_idx);
2008 if (new_source_file_name_idx != 0) {
2009 scratch_class->set_source_file_name_index(new_source_file_name_idx);
2010 }
2011 }
2012
2013 // rewrite class generic signature index:
2014 u2 generic_signature_index = scratch_class->generic_signature_index();
2015 if (generic_signature_index != 0) {
2016 u2 new_generic_signature_index = find_new_index(generic_signature_index);
2017 if (new_generic_signature_index != 0) {
2018 scratch_class->set_generic_signature_index(new_generic_signature_index);
2019 }
2020 }
2021
2022 return true;
2023 } // end rewrite_cp_refs()
2024
2025 // Rewrite constant pool references in the NestHost and NestMembers attributes.
2026 bool VM_RedefineClasses::rewrite_cp_refs_in_nest_attributes(
2027 InstanceKlass* scratch_class) {
2028
2029 u2 cp_index = scratch_class->nest_host_index();
2030 if (cp_index != 0) {
2031 scratch_class->set_nest_host_index(find_new_index(cp_index));
2032 }
2033 Array<u2>* nest_members = scratch_class->nest_members();
2034 for (int i = 0; i < nest_members->length(); i++) {
2035 u2 cp_index = nest_members->at(i);
2036 nest_members->at_put(i, find_new_index(cp_index));
2037 }
2038 return true;
2039 }
2040
2041 // Rewrite constant pool references in the Record attribute.
2042 bool VM_RedefineClasses::rewrite_cp_refs_in_record_attribute(InstanceKlass* scratch_class) {
2043 Array<RecordComponent*>* components = scratch_class->record_components();
2044 if (components != nullptr) {
2045 for (int i = 0; i < components->length(); i++) {
2046 RecordComponent* component = components->at(i);
2047 u2 cp_index = component->name_index();
2048 component->set_name_index(find_new_index(cp_index));
2049 cp_index = component->descriptor_index();
2050 component->set_descriptor_index(find_new_index(cp_index));
2051 cp_index = component->generic_signature_index();
2052 if (cp_index != 0) {
2053 component->set_generic_signature_index(find_new_index(cp_index));
2054 }
2055
2056 AnnotationArray* annotations = component->annotations();
2057 if (annotations != nullptr && annotations->length() != 0) {
2058 int byte_i = 0; // byte index into annotations
2059 if (!rewrite_cp_refs_in_annotations_typeArray(annotations, byte_i)) {
2060 log_debug(redefine, class, annotation)("bad record_component_annotations at %d", i);
2061 // propagate failure back to caller
2062 return false;
2063 }
2064 }
2065
2066 AnnotationArray* type_annotations = component->type_annotations();
2067 if (type_annotations != nullptr && type_annotations->length() != 0) {
2068 int byte_i = 0; // byte index into annotations
2069 if (!rewrite_cp_refs_in_annotations_typeArray(type_annotations, byte_i)) {
2070 log_debug(redefine, class, annotation)("bad record_component_type_annotations at %d", i);
2071 // propagate failure back to caller
2072 return false;
2073 }
2074 }
2075 }
2076 }
2077 return true;
2078 }
2079
2080 // Rewrite constant pool references in the PermittedSubclasses attribute.
2081 bool VM_RedefineClasses::rewrite_cp_refs_in_permitted_subclasses_attribute(
2082 InstanceKlass* scratch_class) {
2083
2084 Array<u2>* permitted_subclasses = scratch_class->permitted_subclasses();
2085 assert(permitted_subclasses != nullptr, "unexpected null permitted_subclasses");
2086 for (int i = 0; i < permitted_subclasses->length(); i++) {
2087 u2 cp_index = permitted_subclasses->at(i);
2088 permitted_subclasses->at_put(i, find_new_index(cp_index));
2089 }
2090 return true;
2091 }
2092
2093 // Rewrite constant pool references in the LoadableDescriptors attribute.
2094 bool VM_RedefineClasses::rewrite_cp_refs_in_loadable_descriptors_attribute(
2095 InstanceKlass* scratch_class) {
2096
2097 Array<u2>* loadable_descriptors = scratch_class->loadable_descriptors();
2098 assert(loadable_descriptors != nullptr, "unexpected null loadable_descriptors");
2099 for (int i = 0; i < loadable_descriptors->length(); i++) {
2100 u2 cp_index = loadable_descriptors->at(i);
2101 loadable_descriptors->at_put(i, find_new_index(cp_index));
2102 }
2103 return true;
2104 }
2105
2106 // Rewrite constant pool references in the methods.
2107 bool VM_RedefineClasses::rewrite_cp_refs_in_methods(InstanceKlass* scratch_class) {
2108
2109 Array<Method*>* methods = scratch_class->methods();
2110
2111 if (methods == nullptr || methods->length() == 0) {
2112 // no methods so nothing to do
2113 return true;
2114 }
2115
2116 JavaThread* THREAD = JavaThread::current(); // For exception macros.
2117 ExceptionMark em(THREAD);
2118
2119 // rewrite constant pool references in the methods:
2120 for (int i = methods->length() - 1; i >= 0; i--) {
2121 methodHandle method(THREAD, methods->at(i));
2122 methodHandle new_method;
2123 rewrite_cp_refs_in_method(method, &new_method, THREAD);
2124 if (!new_method.is_null()) {
2125 // the method has been replaced so save the new method version
2126 // even in the case of an exception. original method is on the
2127 // deallocation list.
2128 methods->at_put(i, new_method());
2129 }
2130 if (HAS_PENDING_EXCEPTION) {
2131 Symbol* ex_name = PENDING_EXCEPTION->klass()->name();
2132 log_info(redefine, class, load, exceptions)("rewrite_cp_refs_in_method exception: '%s'", ex_name->as_C_string());
2133 // Need to clear pending exception here as the super caller sets
2134 // the JVMTI_ERROR_INTERNAL if the returned value is false.
2135 CLEAR_PENDING_EXCEPTION;
2136 return false;
2137 }
2138 }
2139
2140 return true;
2141 }
2142
2143
2144 // Rewrite constant pool references in the specific method. This code
2145 // was adapted from Rewriter::rewrite_method().
2146 void VM_RedefineClasses::rewrite_cp_refs_in_method(methodHandle method,
2147 methodHandle *new_method_p, TRAPS) {
2148
2149 *new_method_p = methodHandle(); // default is no new method
2150
2151 // We cache a pointer to the bytecodes here in code_base. If GC
2152 // moves the Method*, then the bytecodes will also move which
2153 // will likely cause a crash. We create a NoSafepointVerifier
2154 // object to detect whether we pass a possible safepoint in this
2155 // code block.
2156 NoSafepointVerifier nsv;
2157
2158 // Bytecodes and their length
2159 address code_base = method->code_base();
2160 int code_length = method->code_size();
2161
2162 int bc_length;
2163 for (int bci = 0; bci < code_length; bci += bc_length) {
2164 address bcp = code_base + bci;
2165 Bytecodes::Code c = (Bytecodes::Code)(*bcp);
2166
2167 bc_length = Bytecodes::length_for(c);
2168 if (bc_length == 0) {
2169 // More complicated bytecodes report a length of zero so
2170 // we have to try again a slightly different way.
2171 bc_length = Bytecodes::length_at(method(), bcp);
2172 }
2173
2174 assert(bc_length != 0, "impossible bytecode length");
2175
2176 switch (c) {
2177 case Bytecodes::_ldc:
2178 {
2179 u1 cp_index = *(bcp + 1);
2180 u2 new_index = find_new_index(cp_index);
2181
2182 if (StressLdcRewrite && new_index == 0) {
2183 // If we are stressing ldc -> ldc_w rewriting, then we
2184 // always need a new_index value.
2185 new_index = cp_index;
2186 }
2187 if (new_index != 0) {
2188 // the original index is mapped so we have more work to do
2189 if (!StressLdcRewrite && new_index <= max_jubyte) {
2190 // The new value can still use ldc instead of ldc_w
2191 // unless we are trying to stress ldc -> ldc_w rewriting
2192 log_trace(redefine, class, constantpool)
2193 ("%s@" INTPTR_FORMAT " old=%d, new=%d", Bytecodes::name(c), p2i(bcp), cp_index, new_index);
2194 // We checked that new_index fits in a u1 so this cast is safe
2195 *(bcp + 1) = (u1)new_index;
2196 } else {
2197 log_trace(redefine, class, constantpool)
2198 ("%s->ldc_w@" INTPTR_FORMAT " old=%d, new=%d", Bytecodes::name(c), p2i(bcp), cp_index, new_index);
2199 // the new value needs ldc_w instead of ldc
2200 u_char inst_buffer[4]; // max instruction size is 4 bytes
2201 bcp = (address)inst_buffer;
2202 // construct new instruction sequence
2203 *bcp = Bytecodes::_ldc_w;
2204 bcp++;
2205 // Rewriter::rewrite_method() does not rewrite ldc -> ldc_w.
2206 // See comment below for difference between put_Java_u2()
2207 // and put_native_u2().
2208 Bytes::put_Java_u2(bcp, new_index);
2209
2210 Relocator rc(method, nullptr /* no RelocatorListener needed */);
2211 methodHandle m;
2212 {
2213 PauseNoSafepointVerifier pnsv(&nsv);
2214
2215 // ldc is 2 bytes and ldc_w is 3 bytes
2216 m = rc.insert_space_at(bci, 3, inst_buffer, CHECK);
2217 }
2218
2219 // return the new method so that the caller can update
2220 // the containing class
2221 *new_method_p = method = m;
2222 // switch our bytecode processing loop from the old method
2223 // to the new method
2224 code_base = method->code_base();
2225 code_length = method->code_size();
2226 bcp = code_base + bci;
2227 c = (Bytecodes::Code)(*bcp);
2228 bc_length = Bytecodes::length_for(c);
2229 assert(bc_length != 0, "sanity check");
2230 } // end we need ldc_w instead of ldc
2231 } // end if there is a mapped index
2232 } break;
2233
2234 // these bytecodes have a two-byte constant pool index
2235 case Bytecodes::_anewarray : // fall through
2236 case Bytecodes::_checkcast : // fall through
2237 case Bytecodes::_getfield : // fall through
2238 case Bytecodes::_getstatic : // fall through
2239 case Bytecodes::_instanceof : // fall through
2240 case Bytecodes::_invokedynamic : // fall through
2241 case Bytecodes::_invokeinterface: // fall through
2242 case Bytecodes::_invokespecial : // fall through
2243 case Bytecodes::_invokestatic : // fall through
2244 case Bytecodes::_invokevirtual : // fall through
2245 case Bytecodes::_ldc_w : // fall through
2246 case Bytecodes::_ldc2_w : // fall through
2247 case Bytecodes::_multianewarray : // fall through
2248 case Bytecodes::_new : // fall through
2249 case Bytecodes::_putfield : // fall through
2250 case Bytecodes::_putstatic :
2251 {
2252 address p = bcp + 1;
2253 int cp_index = Bytes::get_Java_u2(p);
2254 u2 new_index = find_new_index(cp_index);
2255 if (new_index != 0) {
2256 // the original index is mapped so update w/ new value
2257 log_trace(redefine, class, constantpool)
2258 ("%s@" INTPTR_FORMAT " old=%d, new=%d", Bytecodes::name(c),p2i(bcp), cp_index, new_index);
2259 // Rewriter::rewrite_method() uses put_native_u2() in this
2260 // situation because it is reusing the constant pool index
2261 // location for a native index into the ConstantPoolCache.
2262 // Since we are updating the constant pool index prior to
2263 // verification and ConstantPoolCache initialization, we
2264 // need to keep the new index in Java byte order.
2265 Bytes::put_Java_u2(p, new_index);
2266 }
2267 } break;
2268 default:
2269 break;
2270 }
2271 } // end for each bytecode
2272 } // end rewrite_cp_refs_in_method()
2273
2274
2275 // Rewrite constant pool references in the class_annotations field.
2276 bool VM_RedefineClasses::rewrite_cp_refs_in_class_annotations(InstanceKlass* scratch_class) {
2277
2278 AnnotationArray* class_annotations = scratch_class->class_annotations();
2279 if (class_annotations == nullptr || class_annotations->length() == 0) {
2280 // no class_annotations so nothing to do
2281 return true;
2282 }
2283
2284 log_debug(redefine, class, annotation)("class_annotations length=%d", class_annotations->length());
2285
2286 int byte_i = 0; // byte index into class_annotations
2287 return rewrite_cp_refs_in_annotations_typeArray(class_annotations, byte_i);
2288 }
2289
2290
2291 // Rewrite constant pool references in an annotations typeArray. This
2292 // "structure" is adapted from the RuntimeVisibleAnnotations_attribute
2293 // that is described in section 4.8.15 of the 2nd-edition of the VM spec:
2294 //
2295 // annotations_typeArray {
2296 // u2 num_annotations;
2297 // annotation annotations[num_annotations];
2298 // }
2299 //
2300 bool VM_RedefineClasses::rewrite_cp_refs_in_annotations_typeArray(
2301 AnnotationArray* annotations_typeArray, int &byte_i_ref) {
2302
2303 if ((byte_i_ref + 2) > annotations_typeArray->length()) {
2304 // not enough room for num_annotations field
2305 log_debug(redefine, class, annotation)("length() is too small for num_annotations field");
2306 return false;
2307 }
2308
2309 u2 num_annotations = Bytes::get_Java_u2((address)
2310 annotations_typeArray->adr_at(byte_i_ref));
2311 byte_i_ref += 2;
2312
2313 log_debug(redefine, class, annotation)("num_annotations=%d", num_annotations);
2314
2315 int calc_num_annotations = 0;
2316 for (; calc_num_annotations < num_annotations; calc_num_annotations++) {
2317 if (!rewrite_cp_refs_in_annotation_struct(annotations_typeArray, byte_i_ref)) {
2318 log_debug(redefine, class, annotation)("bad annotation_struct at %d", calc_num_annotations);
2319 // propagate failure back to caller
2320 return false;
2321 }
2322 }
2323 assert(num_annotations == calc_num_annotations, "sanity check");
2324
2325 return true;
2326 } // end rewrite_cp_refs_in_annotations_typeArray()
2327
2328
2329 // Rewrite constant pool references in the annotation struct portion of
2330 // an annotations_typeArray. This "structure" is from section 4.8.15 of
2331 // the 2nd-edition of the VM spec:
2332 //
2333 // struct annotation {
2334 // u2 type_index;
2335 // u2 num_element_value_pairs;
2336 // {
2337 // u2 element_name_index;
2338 // element_value value;
2339 // } element_value_pairs[num_element_value_pairs];
2340 // }
2341 //
2342 bool VM_RedefineClasses::rewrite_cp_refs_in_annotation_struct(
2343 AnnotationArray* annotations_typeArray, int &byte_i_ref) {
2344 if ((byte_i_ref + 2 + 2) > annotations_typeArray->length()) {
2345 // not enough room for smallest annotation_struct
2346 log_debug(redefine, class, annotation)("length() is too small for annotation_struct");
2347 return false;
2348 }
2349
2350 u2 type_index = rewrite_cp_ref_in_annotation_data(annotations_typeArray,
2351 byte_i_ref, "type_index");
2352
2353 u2 num_element_value_pairs = Bytes::get_Java_u2((address)
2354 annotations_typeArray->adr_at(byte_i_ref));
2355 byte_i_ref += 2;
2356
2357 log_debug(redefine, class, annotation)
2358 ("type_index=%d num_element_value_pairs=%d", type_index, num_element_value_pairs);
2359
2360 int calc_num_element_value_pairs = 0;
2361 for (; calc_num_element_value_pairs < num_element_value_pairs;
2362 calc_num_element_value_pairs++) {
2363 if ((byte_i_ref + 2) > annotations_typeArray->length()) {
2364 // not enough room for another element_name_index, let alone
2365 // the rest of another component
2366 log_debug(redefine, class, annotation)("length() is too small for element_name_index");
2367 return false;
2368 }
2369
2370 u2 element_name_index = rewrite_cp_ref_in_annotation_data(
2371 annotations_typeArray, byte_i_ref,
2372 "element_name_index");
2373
2374 log_debug(redefine, class, annotation)("element_name_index=%d", element_name_index);
2375
2376 if (!rewrite_cp_refs_in_element_value(annotations_typeArray, byte_i_ref)) {
2377 log_debug(redefine, class, annotation)("bad element_value at %d", calc_num_element_value_pairs);
2378 // propagate failure back to caller
2379 return false;
2380 }
2381 } // end for each component
2382 assert(num_element_value_pairs == calc_num_element_value_pairs,
2383 "sanity check");
2384
2385 return true;
2386 } // end rewrite_cp_refs_in_annotation_struct()
2387
2388
2389 // Rewrite a constant pool reference at the current position in
2390 // annotations_typeArray if needed. Returns the original constant
2391 // pool reference if a rewrite was not needed or the new constant
2392 // pool reference if a rewrite was needed.
2393 u2 VM_RedefineClasses::rewrite_cp_ref_in_annotation_data(
2394 AnnotationArray* annotations_typeArray, int &byte_i_ref,
2395 const char * trace_mesg) {
2396
2397 address cp_index_addr = (address)
2398 annotations_typeArray->adr_at(byte_i_ref);
2399 u2 old_cp_index = Bytes::get_Java_u2(cp_index_addr);
2400 u2 new_cp_index = find_new_index(old_cp_index);
2401 if (new_cp_index != 0) {
2402 log_debug(redefine, class, annotation)("mapped old %s=%d", trace_mesg, old_cp_index);
2403 Bytes::put_Java_u2(cp_index_addr, new_cp_index);
2404 old_cp_index = new_cp_index;
2405 }
2406 byte_i_ref += 2;
2407 return old_cp_index;
2408 }
2409
2410
2411 // Rewrite constant pool references in the element_value portion of an
2412 // annotations_typeArray. This "structure" is from section 4.8.15.1 of
2413 // the 2nd-edition of the VM spec:
2414 //
2415 // struct element_value {
2416 // u1 tag;
2417 // union {
2418 // u2 const_value_index;
2419 // {
2420 // u2 type_name_index;
2421 // u2 const_name_index;
2422 // } enum_const_value;
2423 // u2 class_info_index;
2424 // annotation annotation_value;
2425 // struct {
2426 // u2 num_values;
2427 // element_value values[num_values];
2428 // } array_value;
2429 // } value;
2430 // }
2431 //
2432 bool VM_RedefineClasses::rewrite_cp_refs_in_element_value(
2433 AnnotationArray* annotations_typeArray, int &byte_i_ref) {
2434
2435 if ((byte_i_ref + 1) > annotations_typeArray->length()) {
2436 // not enough room for a tag let alone the rest of an element_value
2437 log_debug(redefine, class, annotation)("length() is too small for a tag");
2438 return false;
2439 }
2440
2441 u1 tag = annotations_typeArray->at(byte_i_ref);
2442 byte_i_ref++;
2443 log_debug(redefine, class, annotation)("tag='%c'", tag);
2444
2445 switch (tag) {
2446 // These BaseType tag values are from Table 4.2 in VM spec:
2447 case JVM_SIGNATURE_BYTE:
2448 case JVM_SIGNATURE_CHAR:
2449 case JVM_SIGNATURE_DOUBLE:
2450 case JVM_SIGNATURE_FLOAT:
2451 case JVM_SIGNATURE_INT:
2452 case JVM_SIGNATURE_LONG:
2453 case JVM_SIGNATURE_SHORT:
2454 case JVM_SIGNATURE_BOOLEAN:
2455
2456 // The remaining tag values are from Table 4.8 in the 2nd-edition of
2457 // the VM spec:
2458 case 's':
2459 {
2460 // For the above tag values (including the BaseType values),
2461 // value.const_value_index is right union field.
2462
2463 if ((byte_i_ref + 2) > annotations_typeArray->length()) {
2464 // not enough room for a const_value_index
2465 log_debug(redefine, class, annotation)("length() is too small for a const_value_index");
2466 return false;
2467 }
2468
2469 u2 const_value_index = rewrite_cp_ref_in_annotation_data(
2470 annotations_typeArray, byte_i_ref,
2471 "const_value_index");
2472
2473 log_debug(redefine, class, annotation)("const_value_index=%d", const_value_index);
2474 } break;
2475
2476 case 'e':
2477 {
2478 // for the above tag value, value.enum_const_value is right union field
2479
2480 if ((byte_i_ref + 4) > annotations_typeArray->length()) {
2481 // not enough room for a enum_const_value
2482 log_debug(redefine, class, annotation)("length() is too small for a enum_const_value");
2483 return false;
2484 }
2485
2486 u2 type_name_index = rewrite_cp_ref_in_annotation_data(
2487 annotations_typeArray, byte_i_ref,
2488 "type_name_index");
2489
2490 u2 const_name_index = rewrite_cp_ref_in_annotation_data(
2491 annotations_typeArray, byte_i_ref,
2492 "const_name_index");
2493
2494 log_debug(redefine, class, annotation)
2495 ("type_name_index=%d const_name_index=%d", type_name_index, const_name_index);
2496 } break;
2497
2498 case 'c':
2499 {
2500 // for the above tag value, value.class_info_index is right union field
2501
2502 if ((byte_i_ref + 2) > annotations_typeArray->length()) {
2503 // not enough room for a class_info_index
2504 log_debug(redefine, class, annotation)("length() is too small for a class_info_index");
2505 return false;
2506 }
2507
2508 u2 class_info_index = rewrite_cp_ref_in_annotation_data(
2509 annotations_typeArray, byte_i_ref,
2510 "class_info_index");
2511
2512 log_debug(redefine, class, annotation)("class_info_index=%d", class_info_index);
2513 } break;
2514
2515 case '@':
2516 // For the above tag value, value.attr_value is the right union
2517 // field. This is a nested annotation.
2518 if (!rewrite_cp_refs_in_annotation_struct(annotations_typeArray, byte_i_ref)) {
2519 // propagate failure back to caller
2520 return false;
2521 }
2522 break;
2523
2524 case JVM_SIGNATURE_ARRAY:
2525 {
2526 if ((byte_i_ref + 2) > annotations_typeArray->length()) {
2527 // not enough room for a num_values field
2528 log_debug(redefine, class, annotation)("length() is too small for a num_values field");
2529 return false;
2530 }
2531
2532 // For the above tag value, value.array_value is the right union
2533 // field. This is an array of nested element_value.
2534 u2 num_values = Bytes::get_Java_u2((address)
2535 annotations_typeArray->adr_at(byte_i_ref));
2536 byte_i_ref += 2;
2537 log_debug(redefine, class, annotation)("num_values=%d", num_values);
2538
2539 int calc_num_values = 0;
2540 for (; calc_num_values < num_values; calc_num_values++) {
2541 if (!rewrite_cp_refs_in_element_value(annotations_typeArray, byte_i_ref)) {
2542 log_debug(redefine, class, annotation)("bad nested element_value at %d", calc_num_values);
2543 // propagate failure back to caller
2544 return false;
2545 }
2546 }
2547 assert(num_values == calc_num_values, "sanity check");
2548 } break;
2549
2550 default:
2551 log_debug(redefine, class, annotation)("bad tag=0x%x", tag);
2552 return false;
2553 } // end decode tag field
2554
2555 return true;
2556 } // end rewrite_cp_refs_in_element_value()
2557
2558
2559 // Rewrite constant pool references in a fields_annotations field.
2560 bool VM_RedefineClasses::rewrite_cp_refs_in_fields_annotations(
2561 InstanceKlass* scratch_class) {
2562
2563 Array<AnnotationArray*>* fields_annotations = scratch_class->fields_annotations();
2564
2565 if (fields_annotations == nullptr || fields_annotations->length() == 0) {
2566 // no fields_annotations so nothing to do
2567 return true;
2568 }
2569
2570 log_debug(redefine, class, annotation)("fields_annotations length=%d", fields_annotations->length());
2571
2572 for (int i = 0; i < fields_annotations->length(); i++) {
2573 AnnotationArray* field_annotations = fields_annotations->at(i);
2574 if (field_annotations == nullptr || field_annotations->length() == 0) {
2575 // this field does not have any annotations so skip it
2576 continue;
2577 }
2578
2579 int byte_i = 0; // byte index into field_annotations
2580 if (!rewrite_cp_refs_in_annotations_typeArray(field_annotations, byte_i)) {
2581 log_debug(redefine, class, annotation)("bad field_annotations at %d", i);
2582 // propagate failure back to caller
2583 return false;
2584 }
2585 }
2586
2587 return true;
2588 } // end rewrite_cp_refs_in_fields_annotations()
2589
2590
2591 // Rewrite constant pool references in a methods_annotations field.
2592 bool VM_RedefineClasses::rewrite_cp_refs_in_methods_annotations(
2593 InstanceKlass* scratch_class) {
2594
2595 for (int i = 0; i < scratch_class->methods()->length(); i++) {
2596 Method* m = scratch_class->methods()->at(i);
2597 AnnotationArray* method_annotations = m->constMethod()->method_annotations();
2598
2599 if (method_annotations == nullptr || method_annotations->length() == 0) {
2600 // this method does not have any annotations so skip it
2601 continue;
2602 }
2603
2604 int byte_i = 0; // byte index into method_annotations
2605 if (!rewrite_cp_refs_in_annotations_typeArray(method_annotations, byte_i)) {
2606 log_debug(redefine, class, annotation)("bad method_annotations at %d", i);
2607 // propagate failure back to caller
2608 return false;
2609 }
2610 }
2611
2612 return true;
2613 } // end rewrite_cp_refs_in_methods_annotations()
2614
2615
2616 // Rewrite constant pool references in a methods_parameter_annotations
2617 // field. This "structure" is adapted from the
2618 // RuntimeVisibleParameterAnnotations_attribute described in section
2619 // 4.8.17 of the 2nd-edition of the VM spec:
2620 //
2621 // methods_parameter_annotations_typeArray {
2622 // u1 num_parameters;
2623 // {
2624 // u2 num_annotations;
2625 // annotation annotations[num_annotations];
2626 // } parameter_annotations[num_parameters];
2627 // }
2628 //
2629 bool VM_RedefineClasses::rewrite_cp_refs_in_methods_parameter_annotations(
2630 InstanceKlass* scratch_class) {
2631
2632 for (int i = 0; i < scratch_class->methods()->length(); i++) {
2633 Method* m = scratch_class->methods()->at(i);
2634 AnnotationArray* method_parameter_annotations = m->constMethod()->parameter_annotations();
2635 if (method_parameter_annotations == nullptr
2636 || method_parameter_annotations->length() == 0) {
2637 // this method does not have any parameter annotations so skip it
2638 continue;
2639 }
2640
2641 if (method_parameter_annotations->length() < 1) {
2642 // not enough room for a num_parameters field
2643 log_debug(redefine, class, annotation)("length() is too small for a num_parameters field at %d", i);
2644 return false;
2645 }
2646
2647 int byte_i = 0; // byte index into method_parameter_annotations
2648
2649 u1 num_parameters = method_parameter_annotations->at(byte_i);
2650 byte_i++;
2651
2652 log_debug(redefine, class, annotation)("num_parameters=%d", num_parameters);
2653
2654 int calc_num_parameters = 0;
2655 for (; calc_num_parameters < num_parameters; calc_num_parameters++) {
2656 if (!rewrite_cp_refs_in_annotations_typeArray(method_parameter_annotations, byte_i)) {
2657 log_debug(redefine, class, annotation)("bad method_parameter_annotations at %d", calc_num_parameters);
2658 // propagate failure back to caller
2659 return false;
2660 }
2661 }
2662 assert(num_parameters == calc_num_parameters, "sanity check");
2663 }
2664
2665 return true;
2666 } // end rewrite_cp_refs_in_methods_parameter_annotations()
2667
2668
2669 // Rewrite constant pool references in a methods_default_annotations
2670 // field. This "structure" is adapted from the AnnotationDefault_attribute
2671 // that is described in section 4.8.19 of the 2nd-edition of the VM spec:
2672 //
2673 // methods_default_annotations_typeArray {
2674 // element_value default_value;
2675 // }
2676 //
2677 bool VM_RedefineClasses::rewrite_cp_refs_in_methods_default_annotations(
2678 InstanceKlass* scratch_class) {
2679
2680 for (int i = 0; i < scratch_class->methods()->length(); i++) {
2681 Method* m = scratch_class->methods()->at(i);
2682 AnnotationArray* method_default_annotations = m->constMethod()->default_annotations();
2683 if (method_default_annotations == nullptr
2684 || method_default_annotations->length() == 0) {
2685 // this method does not have any default annotations so skip it
2686 continue;
2687 }
2688
2689 int byte_i = 0; // byte index into method_default_annotations
2690
2691 if (!rewrite_cp_refs_in_element_value(
2692 method_default_annotations, byte_i)) {
2693 log_debug(redefine, class, annotation)("bad default element_value at %d", i);
2694 // propagate failure back to caller
2695 return false;
2696 }
2697 }
2698
2699 return true;
2700 } // end rewrite_cp_refs_in_methods_default_annotations()
2701
2702
2703 // Rewrite constant pool references in a class_type_annotations field.
2704 bool VM_RedefineClasses::rewrite_cp_refs_in_class_type_annotations(
2705 InstanceKlass* scratch_class) {
2706
2707 AnnotationArray* class_type_annotations = scratch_class->class_type_annotations();
2708 if (class_type_annotations == nullptr || class_type_annotations->length() == 0) {
2709 // no class_type_annotations so nothing to do
2710 return true;
2711 }
2712
2713 log_debug(redefine, class, annotation)("class_type_annotations length=%d", class_type_annotations->length());
2714
2715 int byte_i = 0; // byte index into class_type_annotations
2716 return rewrite_cp_refs_in_type_annotations_typeArray(class_type_annotations,
2717 byte_i, "ClassFile");
2718 } // end rewrite_cp_refs_in_class_type_annotations()
2719
2720
2721 // Rewrite constant pool references in a fields_type_annotations field.
2722 bool VM_RedefineClasses::rewrite_cp_refs_in_fields_type_annotations(InstanceKlass* scratch_class) {
2723
2724 Array<AnnotationArray*>* fields_type_annotations = scratch_class->fields_type_annotations();
2725 if (fields_type_annotations == nullptr || fields_type_annotations->length() == 0) {
2726 // no fields_type_annotations so nothing to do
2727 return true;
2728 }
2729
2730 log_debug(redefine, class, annotation)("fields_type_annotations length=%d", fields_type_annotations->length());
2731
2732 for (int i = 0; i < fields_type_annotations->length(); i++) {
2733 AnnotationArray* field_type_annotations = fields_type_annotations->at(i);
2734 if (field_type_annotations == nullptr || field_type_annotations->length() == 0) {
2735 // this field does not have any annotations so skip it
2736 continue;
2737 }
2738
2739 int byte_i = 0; // byte index into field_type_annotations
2740 if (!rewrite_cp_refs_in_type_annotations_typeArray(field_type_annotations,
2741 byte_i, "field_info")) {
2742 log_debug(redefine, class, annotation)("bad field_type_annotations at %d", i);
2743 // propagate failure back to caller
2744 return false;
2745 }
2746 }
2747
2748 return true;
2749 } // end rewrite_cp_refs_in_fields_type_annotations()
2750
2751
2752 // Rewrite constant pool references in a methods_type_annotations field.
2753 bool VM_RedefineClasses::rewrite_cp_refs_in_methods_type_annotations(
2754 InstanceKlass* scratch_class) {
2755
2756 for (int i = 0; i < scratch_class->methods()->length(); i++) {
2757 Method* m = scratch_class->methods()->at(i);
2758 AnnotationArray* method_type_annotations = m->constMethod()->type_annotations();
2759
2760 if (method_type_annotations == nullptr || method_type_annotations->length() == 0) {
2761 // this method does not have any annotations so skip it
2762 continue;
2763 }
2764
2765 log_debug(redefine, class, annotation)("methods type_annotations length=%d", method_type_annotations->length());
2766
2767 int byte_i = 0; // byte index into method_type_annotations
2768 if (!rewrite_cp_refs_in_type_annotations_typeArray(method_type_annotations,
2769 byte_i, "method_info")) {
2770 log_debug(redefine, class, annotation)("bad method_type_annotations at %d", i);
2771 // propagate failure back to caller
2772 return false;
2773 }
2774 }
2775
2776 return true;
2777 } // end rewrite_cp_refs_in_methods_type_annotations()
2778
2779
2780 // Rewrite constant pool references in a type_annotations
2781 // field. This "structure" is adapted from the
2782 // RuntimeVisibleTypeAnnotations_attribute described in
2783 // section 4.7.20 of the Java SE 8 Edition of the VM spec:
2784 //
2785 // type_annotations_typeArray {
2786 // u2 num_annotations;
2787 // type_annotation annotations[num_annotations];
2788 // }
2789 //
2790 bool VM_RedefineClasses::rewrite_cp_refs_in_type_annotations_typeArray(
2791 AnnotationArray* type_annotations_typeArray, int &byte_i_ref,
2792 const char * location_mesg) {
2793
2794 if ((byte_i_ref + 2) > type_annotations_typeArray->length()) {
2795 // not enough room for num_annotations field
2796 log_debug(redefine, class, annotation)("length() is too small for num_annotations field");
2797 return false;
2798 }
2799
2800 u2 num_annotations = Bytes::get_Java_u2((address)
2801 type_annotations_typeArray->adr_at(byte_i_ref));
2802 byte_i_ref += 2;
2803
2804 log_debug(redefine, class, annotation)("num_type_annotations=%d", num_annotations);
2805
2806 int calc_num_annotations = 0;
2807 for (; calc_num_annotations < num_annotations; calc_num_annotations++) {
2808 if (!rewrite_cp_refs_in_type_annotation_struct(type_annotations_typeArray,
2809 byte_i_ref, location_mesg)) {
2810 log_debug(redefine, class, annotation)("bad type_annotation_struct at %d", calc_num_annotations);
2811 // propagate failure back to caller
2812 return false;
2813 }
2814 }
2815 assert(num_annotations == calc_num_annotations, "sanity check");
2816
2817 if (byte_i_ref != type_annotations_typeArray->length()) {
2818 log_debug(redefine, class, annotation)
2819 ("read wrong amount of bytes at end of processing type_annotations_typeArray (%d of %d bytes were read)",
2820 byte_i_ref, type_annotations_typeArray->length());
2821 return false;
2822 }
2823
2824 return true;
2825 } // end rewrite_cp_refs_in_type_annotations_typeArray()
2826
2827
2828 // Rewrite constant pool references in a type_annotation
2829 // field. This "structure" is adapted from the
2830 // RuntimeVisibleTypeAnnotations_attribute described in
2831 // section 4.7.20 of the Java SE 8 Edition of the VM spec:
2832 //
2833 // type_annotation {
2834 // u1 target_type;
2835 // union {
2836 // type_parameter_target;
2837 // supertype_target;
2838 // type_parameter_bound_target;
2839 // empty_target;
2840 // method_formal_parameter_target;
2841 // throws_target;
2842 // localvar_target;
2843 // catch_target;
2844 // offset_target;
2845 // type_argument_target;
2846 // } target_info;
2847 // type_path target_path;
2848 // annotation anno;
2849 // }
2850 //
2851 bool VM_RedefineClasses::rewrite_cp_refs_in_type_annotation_struct(
2852 AnnotationArray* type_annotations_typeArray, int &byte_i_ref,
2853 const char * location_mesg) {
2854
2855 if (!skip_type_annotation_target(type_annotations_typeArray,
2856 byte_i_ref, location_mesg)) {
2857 return false;
2858 }
2859
2860 if (!skip_type_annotation_type_path(type_annotations_typeArray, byte_i_ref)) {
2861 return false;
2862 }
2863
2864 if (!rewrite_cp_refs_in_annotation_struct(type_annotations_typeArray, byte_i_ref)) {
2865 return false;
2866 }
2867
2868 return true;
2869 } // end rewrite_cp_refs_in_type_annotation_struct()
2870
2871
2872 // Read, verify and skip over the target_type and target_info part
2873 // so that rewriting can continue in the later parts of the struct.
2874 //
2875 // u1 target_type;
2876 // union {
2877 // type_parameter_target;
2878 // supertype_target;
2879 // type_parameter_bound_target;
2880 // empty_target;
2881 // method_formal_parameter_target;
2882 // throws_target;
2883 // localvar_target;
2884 // catch_target;
2885 // offset_target;
2886 // type_argument_target;
2887 // } target_info;
2888 //
2889 bool VM_RedefineClasses::skip_type_annotation_target(
2890 AnnotationArray* type_annotations_typeArray, int &byte_i_ref,
2891 const char * location_mesg) {
2892
2893 if ((byte_i_ref + 1) > type_annotations_typeArray->length()) {
2894 // not enough room for a target_type let alone the rest of a type_annotation
2895 log_debug(redefine, class, annotation)("length() is too small for a target_type");
2896 return false;
2897 }
2898
2899 u1 target_type = type_annotations_typeArray->at(byte_i_ref);
2900 byte_i_ref += 1;
2901 log_debug(redefine, class, annotation)("target_type=0x%.2x", target_type);
2902 log_debug(redefine, class, annotation)("location=%s", location_mesg);
2903
2904 // Skip over target_info
2905 switch (target_type) {
2906 case 0x00:
2907 // kind: type parameter declaration of generic class or interface
2908 // location: ClassFile
2909 case 0x01:
2910 // kind: type parameter declaration of generic method or constructor
2911 // location: method_info
2912
2913 {
2914 // struct:
2915 // type_parameter_target {
2916 // u1 type_parameter_index;
2917 // }
2918 //
2919 if ((byte_i_ref + 1) > type_annotations_typeArray->length()) {
2920 log_debug(redefine, class, annotation)("length() is too small for a type_parameter_target");
2921 return false;
2922 }
2923
2924 u1 type_parameter_index = type_annotations_typeArray->at(byte_i_ref);
2925 byte_i_ref += 1;
2926
2927 log_debug(redefine, class, annotation)("type_parameter_target: type_parameter_index=%d", type_parameter_index);
2928 } break;
2929
2930 case 0x10:
2931 // kind: type in extends clause of class or interface declaration
2932 // or in implements clause of interface declaration
2933 // location: ClassFile
2934
2935 {
2936 // struct:
2937 // supertype_target {
2938 // u2 supertype_index;
2939 // }
2940 //
2941 if ((byte_i_ref + 2) > type_annotations_typeArray->length()) {
2942 log_debug(redefine, class, annotation)("length() is too small for a supertype_target");
2943 return false;
2944 }
2945
2946 u2 supertype_index = Bytes::get_Java_u2((address)
2947 type_annotations_typeArray->adr_at(byte_i_ref));
2948 byte_i_ref += 2;
2949
2950 log_debug(redefine, class, annotation)("supertype_target: supertype_index=%d", supertype_index);
2951 } break;
2952
2953 case 0x11:
2954 // kind: type in bound of type parameter declaration of generic class or interface
2955 // location: ClassFile
2956 case 0x12:
2957 // kind: type in bound of type parameter declaration of generic method or constructor
2958 // location: method_info
2959
2960 {
2961 // struct:
2962 // type_parameter_bound_target {
2963 // u1 type_parameter_index;
2964 // u1 bound_index;
2965 // }
2966 //
2967 if ((byte_i_ref + 2) > type_annotations_typeArray->length()) {
2968 log_debug(redefine, class, annotation)("length() is too small for a type_parameter_bound_target");
2969 return false;
2970 }
2971
2972 u1 type_parameter_index = type_annotations_typeArray->at(byte_i_ref);
2973 byte_i_ref += 1;
2974 u1 bound_index = type_annotations_typeArray->at(byte_i_ref);
2975 byte_i_ref += 1;
2976
2977 log_debug(redefine, class, annotation)
2978 ("type_parameter_bound_target: type_parameter_index=%d, bound_index=%d", type_parameter_index, bound_index);
2979 } break;
2980
2981 case 0x13:
2982 // kind: type in field declaration
2983 // location: field_info
2984 case 0x14:
2985 // kind: return type of method, or type of newly constructed object
2986 // location: method_info
2987 case 0x15:
2988 // kind: receiver type of method or constructor
2989 // location: method_info
2990
2991 {
2992 // struct:
2993 // empty_target {
2994 // }
2995 //
2996 log_debug(redefine, class, annotation)("empty_target");
2997 } break;
2998
2999 case 0x16:
3000 // kind: type in formal parameter declaration of method, constructor, or lambda expression
3001 // location: method_info
3002
3003 {
3004 // struct:
3005 // formal_parameter_target {
3006 // u1 formal_parameter_index;
3007 // }
3008 //
3009 if ((byte_i_ref + 1) > type_annotations_typeArray->length()) {
3010 log_debug(redefine, class, annotation)("length() is too small for a formal_parameter_target");
3011 return false;
3012 }
3013
3014 u1 formal_parameter_index = type_annotations_typeArray->at(byte_i_ref);
3015 byte_i_ref += 1;
3016
3017 log_debug(redefine, class, annotation)
3018 ("formal_parameter_target: formal_parameter_index=%d", formal_parameter_index);
3019 } break;
3020
3021 case 0x17:
3022 // kind: type in throws clause of method or constructor
3023 // location: method_info
3024
3025 {
3026 // struct:
3027 // throws_target {
3028 // u2 throws_type_index
3029 // }
3030 //
3031 if ((byte_i_ref + 2) > type_annotations_typeArray->length()) {
3032 log_debug(redefine, class, annotation)("length() is too small for a throws_target");
3033 return false;
3034 }
3035
3036 u2 throws_type_index = Bytes::get_Java_u2((address)
3037 type_annotations_typeArray->adr_at(byte_i_ref));
3038 byte_i_ref += 2;
3039
3040 log_debug(redefine, class, annotation)("throws_target: throws_type_index=%d", throws_type_index);
3041 } break;
3042
3043 case 0x40:
3044 // kind: type in local variable declaration
3045 // location: Code
3046 case 0x41:
3047 // kind: type in resource variable declaration
3048 // location: Code
3049
3050 {
3051 // struct:
3052 // localvar_target {
3053 // u2 table_length;
3054 // struct {
3055 // u2 start_pc;
3056 // u2 length;
3057 // u2 index;
3058 // } table[table_length];
3059 // }
3060 //
3061 if ((byte_i_ref + 2) > type_annotations_typeArray->length()) {
3062 // not enough room for a table_length let alone the rest of a localvar_target
3063 log_debug(redefine, class, annotation)("length() is too small for a localvar_target table_length");
3064 return false;
3065 }
3066
3067 u2 table_length = Bytes::get_Java_u2((address)
3068 type_annotations_typeArray->adr_at(byte_i_ref));
3069 byte_i_ref += 2;
3070
3071 log_debug(redefine, class, annotation)("localvar_target: table_length=%d", table_length);
3072
3073 int table_struct_size = 2 + 2 + 2; // 3 u2 variables per table entry
3074 int table_size = table_length * table_struct_size;
3075
3076 if ((byte_i_ref + table_size) > type_annotations_typeArray->length()) {
3077 // not enough room for a table
3078 log_debug(redefine, class, annotation)("length() is too small for a table array of length %d", table_length);
3079 return false;
3080 }
3081
3082 // Skip over table
3083 byte_i_ref += table_size;
3084 } break;
3085
3086 case 0x42:
3087 // kind: type in exception parameter declaration
3088 // location: Code
3089
3090 {
3091 // struct:
3092 // catch_target {
3093 // u2 exception_table_index;
3094 // }
3095 //
3096 if ((byte_i_ref + 2) > type_annotations_typeArray->length()) {
3097 log_debug(redefine, class, annotation)("length() is too small for a catch_target");
3098 return false;
3099 }
3100
3101 u2 exception_table_index = Bytes::get_Java_u2((address)
3102 type_annotations_typeArray->adr_at(byte_i_ref));
3103 byte_i_ref += 2;
3104
3105 log_debug(redefine, class, annotation)("catch_target: exception_table_index=%d", exception_table_index);
3106 } break;
3107
3108 case 0x43:
3109 // kind: type in instanceof expression
3110 // location: Code
3111 case 0x44:
3112 // kind: type in new expression
3113 // location: Code
3114 case 0x45:
3115 // kind: type in method reference expression using ::new
3116 // location: Code
3117 case 0x46:
3118 // kind: type in method reference expression using ::Identifier
3119 // location: Code
3120
3121 {
3122 // struct:
3123 // offset_target {
3124 // u2 offset;
3125 // }
3126 //
3127 if ((byte_i_ref + 2) > type_annotations_typeArray->length()) {
3128 log_debug(redefine, class, annotation)("length() is too small for a offset_target");
3129 return false;
3130 }
3131
3132 u2 offset = Bytes::get_Java_u2((address)
3133 type_annotations_typeArray->adr_at(byte_i_ref));
3134 byte_i_ref += 2;
3135
3136 log_debug(redefine, class, annotation)("offset_target: offset=%d", offset);
3137 } break;
3138
3139 case 0x47:
3140 // kind: type in cast expression
3141 // location: Code
3142 case 0x48:
3143 // kind: type argument for generic constructor in new expression or
3144 // explicit constructor invocation statement
3145 // location: Code
3146 case 0x49:
3147 // kind: type argument for generic method in method invocation expression
3148 // location: Code
3149 case 0x4A:
3150 // kind: type argument for generic constructor in method reference expression using ::new
3151 // location: Code
3152 case 0x4B:
3153 // kind: type argument for generic method in method reference expression using ::Identifier
3154 // location: Code
3155
3156 {
3157 // struct:
3158 // type_argument_target {
3159 // u2 offset;
3160 // u1 type_argument_index;
3161 // }
3162 //
3163 if ((byte_i_ref + 3) > type_annotations_typeArray->length()) {
3164 log_debug(redefine, class, annotation)("length() is too small for a type_argument_target");
3165 return false;
3166 }
3167
3168 u2 offset = Bytes::get_Java_u2((address)
3169 type_annotations_typeArray->adr_at(byte_i_ref));
3170 byte_i_ref += 2;
3171 u1 type_argument_index = type_annotations_typeArray->at(byte_i_ref);
3172 byte_i_ref += 1;
3173
3174 log_debug(redefine, class, annotation)
3175 ("type_argument_target: offset=%d, type_argument_index=%d", offset, type_argument_index);
3176 } break;
3177
3178 default:
3179 log_debug(redefine, class, annotation)("unknown target_type");
3180 #ifdef ASSERT
3181 ShouldNotReachHere();
3182 #endif
3183 return false;
3184 }
3185
3186 return true;
3187 } // end skip_type_annotation_target()
3188
3189
3190 // Read, verify and skip over the type_path part so that rewriting
3191 // can continue in the later parts of the struct.
3192 //
3193 // type_path {
3194 // u1 path_length;
3195 // {
3196 // u1 type_path_kind;
3197 // u1 type_argument_index;
3198 // } path[path_length];
3199 // }
3200 //
3201 bool VM_RedefineClasses::skip_type_annotation_type_path(
3202 AnnotationArray* type_annotations_typeArray, int &byte_i_ref) {
3203
3204 if ((byte_i_ref + 1) > type_annotations_typeArray->length()) {
3205 // not enough room for a path_length let alone the rest of the type_path
3206 log_debug(redefine, class, annotation)("length() is too small for a type_path");
3207 return false;
3208 }
3209
3210 u1 path_length = type_annotations_typeArray->at(byte_i_ref);
3211 byte_i_ref += 1;
3212
3213 log_debug(redefine, class, annotation)("type_path: path_length=%d", path_length);
3214
3215 int calc_path_length = 0;
3216 for (; calc_path_length < path_length; calc_path_length++) {
3217 if ((byte_i_ref + 1 + 1) > type_annotations_typeArray->length()) {
3218 // not enough room for a path
3219 log_debug(redefine, class, annotation)
3220 ("length() is too small for path entry %d of %d", calc_path_length, path_length);
3221 return false;
3222 }
3223
3224 u1 type_path_kind = type_annotations_typeArray->at(byte_i_ref);
3225 byte_i_ref += 1;
3226 u1 type_argument_index = type_annotations_typeArray->at(byte_i_ref);
3227 byte_i_ref += 1;
3228
3229 log_debug(redefine, class, annotation)
3230 ("type_path: path[%d]: type_path_kind=%d, type_argument_index=%d",
3231 calc_path_length, type_path_kind, type_argument_index);
3232
3233 if (type_path_kind > 3 || (type_path_kind != 3 && type_argument_index != 0)) {
3234 // not enough room for a path
3235 log_debug(redefine, class, annotation)("inconsistent type_path values");
3236 return false;
3237 }
3238 }
3239 assert(path_length == calc_path_length, "sanity check");
3240
3241 return true;
3242 } // end skip_type_annotation_type_path()
3243
3244
3245 // Rewrite constant pool references in the method's stackmap table.
3246 // These "structures" are adapted from the StackMapTable_attribute that
3247 // is described in section 4.8.4 of the 6.0 version of the VM spec
3248 // (dated 2005.10.26):
3249 // file:///net/quincunx.sfbay/export/gbracha/ClassFile-Java6.pdf
3250 //
3251 // stack_map {
3252 // u2 number_of_entries;
3253 // stack_map_frame entries[number_of_entries];
3254 // }
3255 //
3256 void VM_RedefineClasses::rewrite_cp_refs_in_stack_map_table(
3257 const methodHandle& method) {
3258
3259 if (!method->has_stackmap_table()) {
3260 return;
3261 }
3262
3263 AnnotationArray* stackmap_data = method->stackmap_data();
3264 address stackmap_p = (address)stackmap_data->adr_at(0);
3265 address stackmap_end = stackmap_p + stackmap_data->length();
3266
3267 assert(stackmap_p + 2 <= stackmap_end, "no room for number_of_entries");
3268 u2 number_of_entries = Bytes::get_Java_u2(stackmap_p);
3269 stackmap_p += 2;
3270
3271 log_debug(redefine, class, stackmap)("number_of_entries=%u", number_of_entries);
3272
3273 // walk through each stack_map_frame
3274 u2 calc_number_of_entries = 0;
3275 for (; calc_number_of_entries < number_of_entries; calc_number_of_entries++) {
3276 // The stack_map_frame structure is a u1 frame_type followed by
3277 // 0 or more bytes of data:
3278 //
3279 // union stack_map_frame {
3280 // same_frame;
3281 // same_locals_1_stack_item_frame;
3282 // same_locals_1_stack_item_frame_extended;
3283 // chop_frame;
3284 // same_frame_extended;
3285 // append_frame;
3286 // full_frame;
3287 // }
3288
3289 assert(stackmap_p + 1 <= stackmap_end, "no room for frame_type");
3290 u1 frame_type = *stackmap_p;
3291 stackmap_p++;
3292
3293 // same_frame {
3294 // u1 frame_type = SAME; /* 0-63 */
3295 // }
3296 if (frame_type <= 63) {
3297 // nothing more to do for same_frame
3298 }
3299
3300 // same_locals_1_stack_item_frame {
3301 // u1 frame_type = SAME_LOCALS_1_STACK_ITEM; /* 64-127 */
3302 // verification_type_info stack[1];
3303 // }
3304 else if (frame_type >= 64 && frame_type <= 127) {
3305 rewrite_cp_refs_in_verification_type_info(stackmap_p, stackmap_end,
3306 calc_number_of_entries, frame_type);
3307 }
3308
3309 // reserved for future use
3310 else if (frame_type >= 128 && frame_type <= 246) {
3311 // nothing more to do for reserved frame_types
3312 }
3313
3314 // same_locals_1_stack_item_frame_extended {
3315 // u1 frame_type = SAME_LOCALS_1_STACK_ITEM_EXTENDED; /* 247 */
3316 // u2 offset_delta;
3317 // verification_type_info stack[1];
3318 // }
3319 else if (frame_type == 247) {
3320 stackmap_p += 2;
3321 rewrite_cp_refs_in_verification_type_info(stackmap_p, stackmap_end,
3322 calc_number_of_entries, frame_type);
3323 }
3324
3325 // chop_frame {
3326 // u1 frame_type = CHOP; /* 248-250 */
3327 // u2 offset_delta;
3328 // }
3329 else if (frame_type >= 248 && frame_type <= 250) {
3330 stackmap_p += 2;
3331 }
3332
3333 // same_frame_extended {
3334 // u1 frame_type = SAME_FRAME_EXTENDED; /* 251*/
3335 // u2 offset_delta;
3336 // }
3337 else if (frame_type == 251) {
3338 stackmap_p += 2;
3339 }
3340
3341 // append_frame {
3342 // u1 frame_type = APPEND; /* 252-254 */
3343 // u2 offset_delta;
3344 // verification_type_info locals[frame_type - 251];
3345 // }
3346 else if (frame_type >= 252 && frame_type <= 254) {
3347 assert(stackmap_p + 2 <= stackmap_end,
3348 "no room for offset_delta");
3349 stackmap_p += 2;
3350 u1 len = frame_type - 251;
3351 for (u1 i = 0; i < len; i++) {
3352 rewrite_cp_refs_in_verification_type_info(stackmap_p, stackmap_end,
3353 calc_number_of_entries, frame_type);
3354 }
3355 }
3356
3357 // full_frame {
3358 // u1 frame_type = FULL_FRAME; /* 255 */
3359 // u2 offset_delta;
3360 // u2 number_of_locals;
3361 // verification_type_info locals[number_of_locals];
3362 // u2 number_of_stack_items;
3363 // verification_type_info stack[number_of_stack_items];
3364 // }
3365 else if (frame_type == 255) {
3366 assert(stackmap_p + 2 + 2 <= stackmap_end,
3367 "no room for smallest full_frame");
3368 stackmap_p += 2;
3369
3370 u2 number_of_locals = Bytes::get_Java_u2(stackmap_p);
3371 stackmap_p += 2;
3372
3373 for (u2 locals_i = 0; locals_i < number_of_locals; locals_i++) {
3374 rewrite_cp_refs_in_verification_type_info(stackmap_p, stackmap_end,
3375 calc_number_of_entries, frame_type);
3376 }
3377
3378 // Use the largest size for the number_of_stack_items, but only get
3379 // the right number of bytes.
3380 u2 number_of_stack_items = Bytes::get_Java_u2(stackmap_p);
3381 stackmap_p += 2;
3382
3383 for (u2 stack_i = 0; stack_i < number_of_stack_items; stack_i++) {
3384 rewrite_cp_refs_in_verification_type_info(stackmap_p, stackmap_end,
3385 calc_number_of_entries, frame_type);
3386 }
3387 }
3388 } // end while there is a stack_map_frame
3389 assert(number_of_entries == calc_number_of_entries, "sanity check");
3390 } // end rewrite_cp_refs_in_stack_map_table()
3391
3392
3393 // Rewrite constant pool references in the verification type info
3394 // portion of the method's stackmap table. These "structures" are
3395 // adapted from the StackMapTable_attribute that is described in
3396 // section 4.8.4 of the 6.0 version of the VM spec (dated 2005.10.26):
3397 // file:///net/quincunx.sfbay/export/gbracha/ClassFile-Java6.pdf
3398 //
3399 // The verification_type_info structure is a u1 tag followed by 0 or
3400 // more bytes of data:
3401 //
3402 // union verification_type_info {
3403 // Top_variable_info;
3404 // Integer_variable_info;
3405 // Float_variable_info;
3406 // Long_variable_info;
3407 // Double_variable_info;
3408 // Null_variable_info;
3409 // UninitializedThis_variable_info;
3410 // Object_variable_info;
3411 // Uninitialized_variable_info;
3412 // }
3413 //
3414 void VM_RedefineClasses::rewrite_cp_refs_in_verification_type_info(
3415 address& stackmap_p_ref, address stackmap_end, u2 frame_i,
3416 u1 frame_type) {
3417
3418 assert(stackmap_p_ref + 1 <= stackmap_end, "no room for tag");
3419 u1 tag = *stackmap_p_ref;
3420 stackmap_p_ref++;
3421
3422 switch (tag) {
3423 // Top_variable_info {
3424 // u1 tag = ITEM_Top; /* 0 */
3425 // }
3426 // verificationType.hpp has zero as ITEM_Bogus instead of ITEM_Top
3427 case 0: // fall through
3428
3429 // Integer_variable_info {
3430 // u1 tag = ITEM_Integer; /* 1 */
3431 // }
3432 case ITEM_Integer: // fall through
3433
3434 // Float_variable_info {
3435 // u1 tag = ITEM_Float; /* 2 */
3436 // }
3437 case ITEM_Float: // fall through
3438
3439 // Double_variable_info {
3440 // u1 tag = ITEM_Double; /* 3 */
3441 // }
3442 case ITEM_Double: // fall through
3443
3444 // Long_variable_info {
3445 // u1 tag = ITEM_Long; /* 4 */
3446 // }
3447 case ITEM_Long: // fall through
3448
3449 // Null_variable_info {
3450 // u1 tag = ITEM_Null; /* 5 */
3451 // }
3452 case ITEM_Null: // fall through
3453
3454 // UninitializedThis_variable_info {
3455 // u1 tag = ITEM_UninitializedThis; /* 6 */
3456 // }
3457 case ITEM_UninitializedThis:
3458 // nothing more to do for the above tag types
3459 break;
3460
3461 // Object_variable_info {
3462 // u1 tag = ITEM_Object; /* 7 */
3463 // u2 cpool_index;
3464 // }
3465 case ITEM_Object:
3466 {
3467 assert(stackmap_p_ref + 2 <= stackmap_end, "no room for cpool_index");
3468 u2 cpool_index = Bytes::get_Java_u2(stackmap_p_ref);
3469 u2 new_cp_index = find_new_index(cpool_index);
3470 if (new_cp_index != 0) {
3471 log_debug(redefine, class, stackmap)("mapped old cpool_index=%d", cpool_index);
3472 Bytes::put_Java_u2(stackmap_p_ref, new_cp_index);
3473 cpool_index = new_cp_index;
3474 }
3475 stackmap_p_ref += 2;
3476
3477 log_debug(redefine, class, stackmap)
3478 ("frame_i=%u, frame_type=%u, cpool_index=%d", frame_i, frame_type, cpool_index);
3479 } break;
3480
3481 // Uninitialized_variable_info {
3482 // u1 tag = ITEM_Uninitialized; /* 8 */
3483 // u2 offset;
3484 // }
3485 case ITEM_Uninitialized:
3486 assert(stackmap_p_ref + 2 <= stackmap_end, "no room for offset");
3487 stackmap_p_ref += 2;
3488 break;
3489
3490 default:
3491 log_debug(redefine, class, stackmap)("frame_i=%u, frame_type=%u, bad tag=0x%x", frame_i, frame_type, tag);
3492 ShouldNotReachHere();
3493 break;
3494 } // end switch (tag)
3495 } // end rewrite_cp_refs_in_verification_type_info()
3496
3497
3498 // Change the constant pool associated with klass scratch_class to scratch_cp.
3499 // scratch_cp_length elements are copied from scratch_cp to a smaller constant pool
3500 // and the smaller constant pool is associated with scratch_class.
3501 void VM_RedefineClasses::set_new_constant_pool(
3502 ClassLoaderData* loader_data,
3503 InstanceKlass* scratch_class, constantPoolHandle scratch_cp,
3504 int scratch_cp_length, TRAPS) {
3505 assert(scratch_cp->length() >= scratch_cp_length, "sanity check");
3506
3507 // scratch_cp is a merged constant pool and has enough space for a
3508 // worst case merge situation. We want to associate the minimum
3509 // sized constant pool with the klass to save space.
3510 ConstantPool* cp = ConstantPool::allocate(loader_data, scratch_cp_length, CHECK);
3511 constantPoolHandle smaller_cp(THREAD, cp);
3512
3513 // preserve version() value in the smaller copy
3514 int version = scratch_cp->version();
3515 assert(version != 0, "sanity check");
3516 smaller_cp->set_version(version);
3517
3518 // attach klass to new constant pool
3519 // reference to the cp holder is needed for copy_operands()
3520 smaller_cp->set_pool_holder(scratch_class);
3521
3522 smaller_cp->copy_fields(scratch_cp());
3523
3524 scratch_cp->copy_cp_to(1, scratch_cp_length - 1, smaller_cp, 1, THREAD);
3525 if (HAS_PENDING_EXCEPTION) {
3526 // Exception is handled in the caller
3527 loader_data->add_to_deallocate_list(smaller_cp());
3528 return;
3529 }
3530 scratch_cp = smaller_cp;
3531
3532 // attach new constant pool to klass
3533 scratch_class->set_constants(scratch_cp());
3534 scratch_cp->initialize_unresolved_klasses(loader_data, CHECK);
3535
3536 int i; // for portability
3537
3538 // update each field in klass to use new constant pool indices as needed
3539 int java_fields;
3540 int injected_fields;
3541 bool update_required = false;
3542 GrowableArray<FieldInfo>* fields = FieldInfoStream::create_FieldInfoArray(scratch_class->fieldinfo_stream(), &java_fields, &injected_fields);
3543 for (int i = 0; i < java_fields; i++) {
3544 FieldInfo* fi = fields->adr_at(i);
3545 jshort cur_index = fi->name_index();
3546 jshort new_index = find_new_index(cur_index);
3547 if (new_index != 0) {
3548 log_trace(redefine, class, constantpool)("field-name_index change: %d to %d", cur_index, new_index);
3549 fi->set_name_index(new_index);
3550 update_required = true;
3551 }
3552 cur_index = fi->signature_index();
3553 new_index = find_new_index(cur_index);
3554 if (new_index != 0) {
3555 log_trace(redefine, class, constantpool)("field-signature_index change: %d to %d", cur_index, new_index);
3556 fi->set_signature_index(new_index);
3557 update_required = true;
3558 }
3559 cur_index = fi->initializer_index();
3560 new_index = find_new_index(cur_index);
3561 if (new_index != 0) {
3562 log_trace(redefine, class, constantpool)("field-initval_index change: %d to %d", cur_index, new_index);
3563 fi->set_initializer_index(new_index);
3564 update_required = true;
3565 }
3566 cur_index = fi->generic_signature_index();
3567 new_index = find_new_index(cur_index);
3568 if (new_index != 0) {
3569 log_trace(redefine, class, constantpool)("field-generic_signature change: %d to %d", cur_index, new_index);
3570 fi->set_generic_signature_index(new_index);
3571 update_required = true;
3572 }
3573 }
3574 if (update_required) {
3575 Array<u1>* old_stream = scratch_class->fieldinfo_stream();
3576 assert(fields->length() == (java_fields + injected_fields), "Must be");
3577 Array<u1>* new_fis = FieldInfoStream::create_FieldInfoStream(fields, java_fields, injected_fields, scratch_class->class_loader_data(), CHECK);
3578 scratch_class->set_fieldinfo_stream(new_fis);
3579 MetadataFactory::free_array<u1>(scratch_class->class_loader_data(), old_stream);
3580 }
3581
3582 // Update constant pool indices in the inner classes info to use
3583 // new constant indices as needed. The inner classes info is a
3584 // quadruple:
3585 // (inner_class_info, outer_class_info, inner_name, inner_access_flags)
3586 InnerClassesIterator iter(scratch_class);
3587 for (; !iter.done(); iter.next()) {
3588 int cur_index = iter.inner_class_info_index();
3589 if (cur_index == 0) {
3590 continue; // JVM spec. allows null inner class refs so skip it
3591 }
3592 u2 new_index = find_new_index(cur_index);
3593 if (new_index != 0) {
3594 log_trace(redefine, class, constantpool)("inner_class_info change: %d to %d", cur_index, new_index);
3595 iter.set_inner_class_info_index(new_index);
3596 }
3597 cur_index = iter.outer_class_info_index();
3598 new_index = find_new_index(cur_index);
3599 if (new_index != 0) {
3600 log_trace(redefine, class, constantpool)("outer_class_info change: %d to %d", cur_index, new_index);
3601 iter.set_outer_class_info_index(new_index);
3602 }
3603 cur_index = iter.inner_name_index();
3604 new_index = find_new_index(cur_index);
3605 if (new_index != 0) {
3606 log_trace(redefine, class, constantpool)("inner_name change: %d to %d", cur_index, new_index);
3607 iter.set_inner_name_index(new_index);
3608 }
3609 } // end for each inner class
3610
3611 // Attach each method in klass to the new constant pool and update
3612 // to use new constant pool indices as needed:
3613 Array<Method*>* methods = scratch_class->methods();
3614 for (i = methods->length() - 1; i >= 0; i--) {
3615 methodHandle method(THREAD, methods->at(i));
3616 method->set_constants(scratch_cp());
3617
3618 u2 new_index = find_new_index(method->name_index());
3619 if (new_index != 0) {
3620 log_trace(redefine, class, constantpool)
3621 ("method-name_index change: %d to %d", method->name_index(), new_index);
3622 method->set_name_index(new_index);
3623 }
3624 new_index = find_new_index(method->signature_index());
3625 if (new_index != 0) {
3626 log_trace(redefine, class, constantpool)
3627 ("method-signature_index change: %d to %d", method->signature_index(), new_index);
3628 method->set_signature_index(new_index);
3629 }
3630 new_index = find_new_index(method->generic_signature_index());
3631 if (new_index != 0) {
3632 log_trace(redefine, class, constantpool)
3633 ("method-generic_signature_index change: %d to %d", method->generic_signature_index(), new_index);
3634 method->constMethod()->set_generic_signature_index(new_index);
3635 }
3636
3637 // Update constant pool indices in the method's checked exception
3638 // table to use new constant indices as needed.
3639 int cext_length = method->checked_exceptions_length();
3640 if (cext_length > 0) {
3641 CheckedExceptionElement * cext_table =
3642 method->checked_exceptions_start();
3643 for (int j = 0; j < cext_length; j++) {
3644 int cur_index = cext_table[j].class_cp_index;
3645 int new_index = find_new_index(cur_index);
3646 if (new_index != 0) {
3647 log_trace(redefine, class, constantpool)("cext-class_cp_index change: %d to %d", cur_index, new_index);
3648 cext_table[j].class_cp_index = (u2)new_index;
3649 }
3650 } // end for each checked exception table entry
3651 } // end if there are checked exception table entries
3652
3653 // Update each catch type index in the method's exception table
3654 // to use new constant pool indices as needed. The exception table
3655 // holds quadruple entries of the form:
3656 // (beg_bci, end_bci, handler_bci, klass_index)
3657
3658 ExceptionTable ex_table(method());
3659 int ext_length = ex_table.length();
3660
3661 for (int j = 0; j < ext_length; j ++) {
3662 int cur_index = ex_table.catch_type_index(j);
3663 u2 new_index = find_new_index(cur_index);
3664 if (new_index != 0) {
3665 log_trace(redefine, class, constantpool)("ext-klass_index change: %d to %d", cur_index, new_index);
3666 ex_table.set_catch_type_index(j, new_index);
3667 }
3668 } // end for each exception table entry
3669
3670 // Update constant pool indices in the method's local variable
3671 // table to use new constant indices as needed. The local variable
3672 // table hold sextuple entries of the form:
3673 // (start_pc, length, name_index, descriptor_index, signature_index, slot)
3674 int lvt_length = method->localvariable_table_length();
3675 if (lvt_length > 0) {
3676 LocalVariableTableElement * lv_table =
3677 method->localvariable_table_start();
3678 for (int j = 0; j < lvt_length; j++) {
3679 int cur_index = lv_table[j].name_cp_index;
3680 int new_index = find_new_index(cur_index);
3681 if (new_index != 0) {
3682 log_trace(redefine, class, constantpool)("lvt-name_cp_index change: %d to %d", cur_index, new_index);
3683 lv_table[j].name_cp_index = (u2)new_index;
3684 }
3685 cur_index = lv_table[j].descriptor_cp_index;
3686 new_index = find_new_index(cur_index);
3687 if (new_index != 0) {
3688 log_trace(redefine, class, constantpool)("lvt-descriptor_cp_index change: %d to %d", cur_index, new_index);
3689 lv_table[j].descriptor_cp_index = (u2)new_index;
3690 }
3691 cur_index = lv_table[j].signature_cp_index;
3692 new_index = find_new_index(cur_index);
3693 if (new_index != 0) {
3694 log_trace(redefine, class, constantpool)("lvt-signature_cp_index change: %d to %d", cur_index, new_index);
3695 lv_table[j].signature_cp_index = (u2)new_index;
3696 }
3697 } // end for each local variable table entry
3698 } // end if there are local variable table entries
3699
3700 // Update constant pool indices in the method's method_parameters.
3701 int mp_length = method->method_parameters_length();
3702 if (mp_length > 0) {
3703 MethodParametersElement* elem = method->method_parameters_start();
3704 for (int j = 0; j < mp_length; j++) {
3705 const int cp_index = elem[j].name_cp_index;
3706 const int new_cp_index = find_new_index(cp_index);
3707 if (new_cp_index != 0) {
3708 elem[j].name_cp_index = (u2)new_cp_index;
3709 }
3710 }
3711 }
3712
3713 rewrite_cp_refs_in_stack_map_table(method);
3714 } // end for each method
3715 } // end set_new_constant_pool()
3716
3717
3718 // Unevolving classes may point to methods of the_class directly
3719 // from their constant pool caches, itables, and/or vtables. We
3720 // use the ClassLoaderDataGraph::classes_do() facility and this helper
3721 // to fix up these pointers. MethodData also points to old methods and
3722 // must be cleaned.
3723
3724 // Adjust cpools and vtables closure
3725 void VM_RedefineClasses::AdjustAndCleanMetadata::do_klass(Klass* k) {
3726
3727 // This is a very busy routine. We don't want too much tracing
3728 // printed out.
3729 bool trace_name_printed = false;
3730
3731 // If the class being redefined is java.lang.Object, we need to fix all
3732 // array class vtables also. The _has_redefined_Object flag is global.
3733 // Once the java.lang.Object has been redefined (by the current or one
3734 // of the previous VM_RedefineClasses operations) we have to always
3735 // adjust method entries for array classes.
3736 if (k->is_array_klass() && _has_redefined_Object) {
3737 k->vtable().adjust_method_entries(&trace_name_printed);
3738
3739 } else if (k->is_instance_klass()) {
3740 HandleMark hm(_thread);
3741 InstanceKlass *ik = InstanceKlass::cast(k);
3742
3743 // Clean MethodData of this class's methods so they don't refer to
3744 // old methods that are no longer running.
3745 Array<Method*>* methods = ik->methods();
3746 int num_methods = methods->length();
3747 for (int index = 0; index < num_methods; ++index) {
3748 if (methods->at(index)->method_data() != nullptr) {
3749 methods->at(index)->method_data()->clean_weak_method_links();
3750 }
3751 }
3752
3753 // Adjust all vtables, default methods and itables, to clean out old methods.
3754 ResourceMark rm(_thread);
3755 if (ik->vtable_length() > 0) {
3756 ik->vtable().adjust_method_entries(&trace_name_printed);
3757 ik->adjust_default_methods(&trace_name_printed);
3758 }
3759
3760 if (ik->itable_length() > 0) {
3761 ik->itable().adjust_method_entries(&trace_name_printed);
3762 }
3763
3764 // The constant pools in other classes (other_cp) can refer to
3765 // old methods. We have to update method information in
3766 // other_cp's cache. If other_cp has a previous version, then we
3767 // have to repeat the process for each previous version. The
3768 // constant pool cache holds the Method*s for non-virtual
3769 // methods and for virtual, final methods.
3770 //
3771 // Special case: if the current class is being redefined by the current
3772 // VM_RedefineClasses operation, then new_cp has already been attached
3773 // to the_class and old_cp has already been added as a previous version.
3774 // The new_cp doesn't have any cached references to old methods so it
3775 // doesn't need to be updated and we could optimize by skipping it.
3776 // However, the current class can be marked as being redefined by another
3777 // VM_RedefineClasses operation which has already executed its doit_prologue
3778 // and needs cpcache method entries adjusted. For simplicity, the cpcache
3779 // update is done unconditionally. It should result in doing nothing for
3780 // classes being redefined by the current VM_RedefineClasses operation.
3781 // Method entries in the previous version(s) are adjusted as well.
3782 ConstantPoolCache* cp_cache;
3783
3784 // this klass' constant pool cache may need adjustment
3785 ConstantPool* other_cp = ik->constants();
3786 cp_cache = other_cp->cache();
3787 if (cp_cache != nullptr) {
3788 cp_cache->adjust_method_entries(&trace_name_printed);
3789 }
3790
3791 // the previous versions' constant pool caches may need adjustment
3792 for (InstanceKlass* pv_node = ik->previous_versions();
3793 pv_node != nullptr;
3794 pv_node = pv_node->previous_versions()) {
3795 cp_cache = pv_node->constants()->cache();
3796 if (cp_cache != nullptr) {
3797 cp_cache->adjust_method_entries(&trace_name_printed);
3798 }
3799 }
3800 }
3801 }
3802
3803 void VM_RedefineClasses::update_jmethod_ids() {
3804 for (int j = 0; j < _matching_methods_length; ++j) {
3805 Method* old_method = _matching_old_methods[j];
3806 jmethodID jmid = old_method->find_jmethod_id_or_null();
3807 if (jmid != nullptr) {
3808 // There is a jmethodID, change it to point to the new method
3809 Method* new_method = _matching_new_methods[j];
3810 Method::change_method_associated_with_jmethod_id(jmid, new_method);
3811 assert(Method::resolve_jmethod_id(jmid) == _matching_new_methods[j],
3812 "should be replaced");
3813 }
3814 }
3815 }
3816
3817 int VM_RedefineClasses::check_methods_and_mark_as_obsolete() {
3818 int emcp_method_count = 0;
3819 int obsolete_count = 0;
3820 int old_index = 0;
3821 for (int j = 0; j < _matching_methods_length; ++j, ++old_index) {
3822 Method* old_method = _matching_old_methods[j];
3823 Method* new_method = _matching_new_methods[j];
3824 Method* old_array_method;
3825
3826 // Maintain an old_index into the _old_methods array by skipping
3827 // deleted methods
3828 while ((old_array_method = _old_methods->at(old_index)) != old_method) {
3829 ++old_index;
3830 }
3831
3832 if (MethodComparator::methods_EMCP(old_method, new_method)) {
3833 // The EMCP definition from JSR-163 requires the bytecodes to be
3834 // the same with the exception of constant pool indices which may
3835 // differ. However, the constants referred to by those indices
3836 // must be the same.
3837 //
3838 // We use methods_EMCP() for comparison since constant pool
3839 // merging can remove duplicate constant pool entries that were
3840 // present in the old method and removed from the rewritten new
3841 // method. A faster binary comparison function would consider the
3842 // old and new methods to be different when they are actually
3843 // EMCP.
3844 //
3845 // The old and new methods are EMCP and you would think that we
3846 // could get rid of one of them here and now and save some space.
3847 // However, the concept of EMCP only considers the bytecodes and
3848 // the constant pool entries in the comparison. Other things,
3849 // e.g., the line number table (LNT) or the local variable table
3850 // (LVT) don't count in the comparison. So the new (and EMCP)
3851 // method can have a new LNT that we need so we can't just
3852 // overwrite the new method with the old method.
3853 //
3854 // When this routine is called, we have already attached the new
3855 // methods to the_class so the old methods are effectively
3856 // overwritten. However, if an old method is still executing,
3857 // then the old method cannot be collected until sometime after
3858 // the old method call has returned. So the overwriting of old
3859 // methods by new methods will save us space except for those
3860 // (hopefully few) old methods that are still executing.
3861 //
3862 // A method refers to a ConstMethod* and this presents another
3863 // possible avenue to space savings. The ConstMethod* in the
3864 // new method contains possibly new attributes (LNT, LVT, etc).
3865 // At first glance, it seems possible to save space by replacing
3866 // the ConstMethod* in the old method with the ConstMethod*
3867 // from the new method. The old and new methods would share the
3868 // same ConstMethod* and we would save the space occupied by
3869 // the old ConstMethod*. However, the ConstMethod* contains
3870 // a back reference to the containing method. Sharing the
3871 // ConstMethod* between two methods could lead to confusion in
3872 // the code that uses the back reference. This would lead to
3873 // brittle code that could be broken in non-obvious ways now or
3874 // in the future.
3875 //
3876 // Another possibility is to copy the ConstMethod* from the new
3877 // method to the old method and then overwrite the new method with
3878 // the old method. Since the ConstMethod* contains the bytecodes
3879 // for the method embedded in the oop, this option would change
3880 // the bytecodes out from under any threads executing the old
3881 // method and make the thread's bcp invalid. Since EMCP requires
3882 // that the bytecodes be the same modulo constant pool indices, it
3883 // is straight forward to compute the correct new bcp in the new
3884 // ConstMethod* from the old bcp in the old ConstMethod*. The
3885 // time consuming part would be searching all the frames in all
3886 // of the threads to find all of the calls to the old method.
3887 //
3888 // It looks like we will have to live with the limited savings
3889 // that we get from effectively overwriting the old methods
3890 // when the new methods are attached to the_class.
3891
3892 // Count number of methods that are EMCP. The method will be marked
3893 // old but not obsolete if it is EMCP.
3894 emcp_method_count++;
3895
3896 // An EMCP method is _not_ obsolete. An obsolete method has a
3897 // different jmethodID than the current method. An EMCP method
3898 // has the same jmethodID as the current method. Having the
3899 // same jmethodID for all EMCP versions of a method allows for
3900 // a consistent view of the EMCP methods regardless of which
3901 // EMCP method you happen to have in hand. For example, a
3902 // breakpoint set in one EMCP method will work for all EMCP
3903 // versions of the method including the current one.
3904 } else {
3905 // mark obsolete methods as such
3906 old_method->set_is_obsolete();
3907 obsolete_count++;
3908
3909 // obsolete methods need a unique idnum so they become new entries in
3910 // the jmethodID cache in InstanceKlass
3911 assert(old_method->method_idnum() == new_method->method_idnum(), "must match");
3912 u2 num = InstanceKlass::cast(_the_class)->next_method_idnum();
3913 if (num != ConstMethod::UNSET_IDNUM) {
3914 old_method->set_method_idnum(num);
3915 }
3916
3917 // With tracing we try not to "yack" too much. The position of
3918 // this trace assumes there are fewer obsolete methods than
3919 // EMCP methods.
3920 if (log_is_enabled(Trace, redefine, class, obsolete, mark)) {
3921 ResourceMark rm;
3922 log_trace(redefine, class, obsolete, mark)
3923 ("mark %s(%s) as obsolete", old_method->name()->as_C_string(), old_method->signature()->as_C_string());
3924 }
3925 }
3926 old_method->set_is_old();
3927 }
3928 for (int i = 0; i < _deleted_methods_length; ++i) {
3929 Method* old_method = _deleted_methods[i];
3930
3931 assert(!old_method->has_vtable_index(),
3932 "cannot delete methods with vtable entries");;
3933
3934 // Mark all deleted methods as old, obsolete and deleted
3935 old_method->set_is_deleted();
3936 old_method->set_is_old();
3937 old_method->set_is_obsolete();
3938 ++obsolete_count;
3939 // With tracing we try not to "yack" too much. The position of
3940 // this trace assumes there are fewer obsolete methods than
3941 // EMCP methods.
3942 if (log_is_enabled(Trace, redefine, class, obsolete, mark)) {
3943 ResourceMark rm;
3944 log_trace(redefine, class, obsolete, mark)
3945 ("mark deleted %s(%s) as obsolete", old_method->name()->as_C_string(), old_method->signature()->as_C_string());
3946 }
3947 }
3948 assert((emcp_method_count + obsolete_count) == _old_methods->length(),
3949 "sanity check");
3950 log_trace(redefine, class, obsolete, mark)("EMCP_cnt=%d, obsolete_cnt=%d", emcp_method_count, obsolete_count);
3951 return emcp_method_count;
3952 }
3953
3954 // This internal class transfers the native function registration from old methods
3955 // to new methods. It is designed to handle both the simple case of unchanged
3956 // native methods and the complex cases of native method prefixes being added and/or
3957 // removed.
3958 // It expects only to be used during the VM_RedefineClasses op (a safepoint).
3959 //
3960 // This class is used after the new methods have been installed in "the_class".
3961 //
3962 // So, for example, the following must be handled. Where 'm' is a method and
3963 // a number followed by an underscore is a prefix.
3964 //
3965 // Old Name New Name
3966 // Simple transfer to new method m -> m
3967 // Add prefix m -> 1_m
3968 // Remove prefix 1_m -> m
3969 // Simultaneous add of prefixes m -> 3_2_1_m
3970 // Simultaneous removal of prefixes 3_2_1_m -> m
3971 // Simultaneous add and remove 1_m -> 2_m
3972 // Same, caused by prefix removal only 3_2_1_m -> 3_2_m
3973 //
3974 class TransferNativeFunctionRegistration {
3975 private:
3976 InstanceKlass* the_class;
3977 int prefix_count;
3978 char** prefixes;
3979
3980 // Recursively search the binary tree of possibly prefixed method names.
3981 // Iteration could be used if all agents were well behaved. Full tree walk is
3982 // more resilent to agents not cleaning up intermediate methods.
3983 // Branch at each depth in the binary tree is:
3984 // (1) without the prefix.
3985 // (2) with the prefix.
3986 // where 'prefix' is the prefix at that 'depth' (first prefix, second prefix,...)
3987 Method* search_prefix_name_space(int depth, char* name_str, size_t name_len,
3988 Symbol* signature) {
3989 TempNewSymbol name_symbol = SymbolTable::probe(name_str, (int)name_len);
3990 if (name_symbol != nullptr) {
3991 Method* method = the_class->lookup_method(name_symbol, signature);
3992 if (method != nullptr) {
3993 // Even if prefixed, intermediate methods must exist.
3994 if (method->is_native()) {
3995 // Wahoo, we found a (possibly prefixed) version of the method, return it.
3996 return method;
3997 }
3998 if (depth < prefix_count) {
3999 // Try applying further prefixes (other than this one).
4000 method = search_prefix_name_space(depth+1, name_str, name_len, signature);
4001 if (method != nullptr) {
4002 return method; // found
4003 }
4004
4005 // Try adding this prefix to the method name and see if it matches
4006 // another method name.
4007 char* prefix = prefixes[depth];
4008 size_t prefix_len = strlen(prefix);
4009 size_t trial_len = name_len + prefix_len;
4010 char* trial_name_str = NEW_RESOURCE_ARRAY(char, trial_len + 1);
4011 strcpy(trial_name_str, prefix);
4012 strcat(trial_name_str, name_str);
4013 method = search_prefix_name_space(depth+1, trial_name_str, trial_len,
4014 signature);
4015 if (method != nullptr) {
4016 // If found along this branch, it was prefixed, mark as such
4017 method->set_is_prefixed_native();
4018 return method; // found
4019 }
4020 }
4021 }
4022 }
4023 return nullptr; // This whole branch bore nothing
4024 }
4025
4026 // Return the method name with old prefixes stripped away.
4027 char* method_name_without_prefixes(Method* method) {
4028 Symbol* name = method->name();
4029 char* name_str = name->as_utf8();
4030
4031 // Old prefixing may be defunct, strip prefixes, if any.
4032 for (int i = prefix_count-1; i >= 0; i--) {
4033 char* prefix = prefixes[i];
4034 size_t prefix_len = strlen(prefix);
4035 if (strncmp(prefix, name_str, prefix_len) == 0) {
4036 name_str += prefix_len;
4037 }
4038 }
4039 return name_str;
4040 }
4041
4042 // Strip any prefixes off the old native method, then try to find a
4043 // (possibly prefixed) new native that matches it.
4044 Method* strip_and_search_for_new_native(Method* method) {
4045 ResourceMark rm;
4046 char* name_str = method_name_without_prefixes(method);
4047 return search_prefix_name_space(0, name_str, strlen(name_str),
4048 method->signature());
4049 }
4050
4051 public:
4052
4053 // Construct a native method transfer processor for this class.
4054 TransferNativeFunctionRegistration(InstanceKlass* _the_class) {
4055 assert(SafepointSynchronize::is_at_safepoint(), "sanity check");
4056
4057 the_class = _the_class;
4058 prefixes = JvmtiExport::get_all_native_method_prefixes(&prefix_count);
4059 }
4060
4061 // Attempt to transfer any of the old or deleted methods that are native
4062 void transfer_registrations(Method** old_methods, int methods_length) {
4063 for (int j = 0; j < methods_length; j++) {
4064 Method* old_method = old_methods[j];
4065
4066 if (old_method->is_native() && old_method->has_native_function()) {
4067 Method* new_method = strip_and_search_for_new_native(old_method);
4068 if (new_method != nullptr) {
4069 // Actually set the native function in the new method.
4070 // Redefine does not send events (except CFLH), certainly not this
4071 // behind the scenes re-registration.
4072 new_method->set_native_function(old_method->native_function(),
4073 !Method::native_bind_event_is_interesting);
4074 }
4075 }
4076 }
4077 }
4078 };
4079
4080 // Don't lose the association between a native method and its JNI function.
4081 void VM_RedefineClasses::transfer_old_native_function_registrations(InstanceKlass* the_class) {
4082 TransferNativeFunctionRegistration transfer(the_class);
4083 transfer.transfer_registrations(_deleted_methods, _deleted_methods_length);
4084 transfer.transfer_registrations(_matching_old_methods, _matching_methods_length);
4085 }
4086
4087 // Deoptimize all compiled code that depends on the classes redefined.
4088 //
4089 // If the can_redefine_classes capability is obtained in the onload
4090 // phase or 'AlwaysRecordEvolDependencies' is true, then the compiler has
4091 // recorded all dependencies from startup. In that case we need only
4092 // deoptimize and throw away all compiled code that depends on the class.
4093 //
4094 // If can_redefine_classes is obtained sometime after the onload phase
4095 // (and 'AlwaysRecordEvolDependencies' is false) then the dependency
4096 // information may be incomplete. In that case the first call to
4097 // RedefineClasses causes all compiled code to be thrown away. As
4098 // can_redefine_classes has been obtained then all future compilations will
4099 // record dependencies so second and subsequent calls to RedefineClasses
4100 // need only throw away code that depends on the class.
4101 //
4102
4103 void VM_RedefineClasses::flush_dependent_code() {
4104 assert(SafepointSynchronize::is_at_safepoint(), "sanity check");
4105 assert(JvmtiExport::all_dependencies_are_recorded() || !AlwaysRecordEvolDependencies, "sanity check");
4106
4107 DeoptimizationScope deopt_scope;
4108
4109 // This is the first redefinition, mark all the nmethods for deoptimization
4110 if (!JvmtiExport::all_dependencies_are_recorded()) {
4111 CodeCache::mark_all_nmethods_for_evol_deoptimization(&deopt_scope);
4112 log_debug(redefine, class, nmethod)("Marked all nmethods for deopt");
4113 } else {
4114 CodeCache::mark_dependents_for_evol_deoptimization(&deopt_scope);
4115 log_debug(redefine, class, nmethod)("Marked dependent nmethods for deopt");
4116 }
4117
4118 deopt_scope.deoptimize_marked();
4119
4120 // From now on we know that the dependency information is complete
4121 JvmtiExport::set_all_dependencies_are_recorded(true);
4122 }
4123
4124 void VM_RedefineClasses::compute_added_deleted_matching_methods() {
4125 Method* old_method;
4126 Method* new_method;
4127
4128 _matching_old_methods = NEW_RESOURCE_ARRAY(Method*, _old_methods->length());
4129 _matching_new_methods = NEW_RESOURCE_ARRAY(Method*, _old_methods->length());
4130 _added_methods = NEW_RESOURCE_ARRAY(Method*, _new_methods->length());
4131 _deleted_methods = NEW_RESOURCE_ARRAY(Method*, _old_methods->length());
4132
4133 _matching_methods_length = 0;
4134 _deleted_methods_length = 0;
4135 _added_methods_length = 0;
4136
4137 int nj = 0;
4138 int oj = 0;
4139 while (true) {
4140 if (oj >= _old_methods->length()) {
4141 if (nj >= _new_methods->length()) {
4142 break; // we've looked at everything, done
4143 }
4144 // New method at the end
4145 new_method = _new_methods->at(nj);
4146 _added_methods[_added_methods_length++] = new_method;
4147 ++nj;
4148 } else if (nj >= _new_methods->length()) {
4149 // Old method, at the end, is deleted
4150 old_method = _old_methods->at(oj);
4151 _deleted_methods[_deleted_methods_length++] = old_method;
4152 ++oj;
4153 } else {
4154 old_method = _old_methods->at(oj);
4155 new_method = _new_methods->at(nj);
4156 if (old_method->name() == new_method->name()) {
4157 if (old_method->signature() == new_method->signature()) {
4158 _matching_old_methods[_matching_methods_length ] = old_method;
4159 _matching_new_methods[_matching_methods_length++] = new_method;
4160 ++nj;
4161 ++oj;
4162 } else {
4163 // added overloaded have already been moved to the end,
4164 // so this is a deleted overloaded method
4165 _deleted_methods[_deleted_methods_length++] = old_method;
4166 ++oj;
4167 }
4168 } else { // names don't match
4169 if (old_method->name()->fast_compare(new_method->name()) > 0) {
4170 // new method
4171 _added_methods[_added_methods_length++] = new_method;
4172 ++nj;
4173 } else {
4174 // deleted method
4175 _deleted_methods[_deleted_methods_length++] = old_method;
4176 ++oj;
4177 }
4178 }
4179 }
4180 }
4181 assert(_matching_methods_length + _deleted_methods_length == _old_methods->length(), "sanity");
4182 assert(_matching_methods_length + _added_methods_length == _new_methods->length(), "sanity");
4183 }
4184
4185
4186 void VM_RedefineClasses::swap_annotations(InstanceKlass* the_class,
4187 InstanceKlass* scratch_class) {
4188 // Swap annotation fields values
4189 Annotations* old_annotations = the_class->annotations();
4190 the_class->set_annotations(scratch_class->annotations());
4191 scratch_class->set_annotations(old_annotations);
4192 }
4193
4194
4195 // Install the redefinition of a class:
4196 // - house keeping (flushing breakpoints and caches, deoptimizing
4197 // dependent compiled code)
4198 // - replacing parts in the_class with parts from scratch_class
4199 // - adding a weak reference to track the obsolete but interesting
4200 // parts of the_class
4201 // - adjusting constant pool caches and vtables in other classes
4202 // that refer to methods in the_class. These adjustments use the
4203 // ClassLoaderDataGraph::classes_do() facility which only allows
4204 // a helper method to be specified. The interesting parameters
4205 // that we would like to pass to the helper method are saved in
4206 // static global fields in the VM operation.
4207 void VM_RedefineClasses::redefine_single_class(Thread* current, jclass the_jclass,
4208 InstanceKlass* scratch_class) {
4209
4210 HandleMark hm(current); // make sure handles from this call are freed
4211
4212 if (log_is_enabled(Info, redefine, class, timer)) {
4213 _timer_rsc_phase1.start();
4214 }
4215
4216 InstanceKlass* the_class = get_ik(the_jclass);
4217
4218 // Set a flag to control and optimize adjusting method entries
4219 _has_redefined_Object |= the_class == vmClasses::Object_klass();
4220
4221 // Remove all breakpoints in methods of this class
4222 JvmtiBreakpoints& jvmti_breakpoints = JvmtiCurrentBreakpoints::get_jvmti_breakpoints();
4223 jvmti_breakpoints.clearall_in_class_at_safepoint(the_class);
4224
4225 _old_methods = the_class->methods();
4226 _new_methods = scratch_class->methods();
4227 _the_class = the_class;
4228 compute_added_deleted_matching_methods();
4229 update_jmethod_ids();
4230
4231 _any_class_has_resolved_methods = the_class->has_resolved_methods() || _any_class_has_resolved_methods;
4232
4233 // Attach new constant pool to the original klass. The original
4234 // klass still refers to the old constant pool (for now).
4235 scratch_class->constants()->set_pool_holder(the_class);
4236
4237 #if 0
4238 // In theory, with constant pool merging in place we should be able
4239 // to save space by using the new, merged constant pool in place of
4240 // the old constant pool(s). By "pool(s)" I mean the constant pool in
4241 // the klass version we are replacing now and any constant pool(s) in
4242 // previous versions of klass. Nice theory, doesn't work in practice.
4243 // When this code is enabled, even simple programs throw NullPointer
4244 // exceptions. I'm guessing that this is caused by some constant pool
4245 // cache difference between the new, merged constant pool and the
4246 // constant pool that was just being used by the klass. I'm keeping
4247 // this code around to archive the idea, but the code has to remain
4248 // disabled for now.
4249
4250 // Attach each old method to the new constant pool. This can be
4251 // done here since we are past the bytecode verification and
4252 // constant pool optimization phases.
4253 for (int i = _old_methods->length() - 1; i >= 0; i--) {
4254 Method* method = _old_methods->at(i);
4255 method->set_constants(scratch_class->constants());
4256 }
4257
4258 // NOTE: this doesn't work because you can redefine the same class in two
4259 // threads, each getting their own constant pool data appended to the
4260 // original constant pool. In order for the new methods to work when they
4261 // become old methods, they need to keep their updated copy of the constant pool.
4262
4263 {
4264 // walk all previous versions of the klass
4265 InstanceKlass *ik = the_class;
4266 PreviousVersionWalker pvw(ik);
4267 do {
4268 ik = pvw.next_previous_version();
4269 if (ik != nullptr) {
4270
4271 // attach previous version of klass to the new constant pool
4272 ik->set_constants(scratch_class->constants());
4273
4274 // Attach each method in the previous version of klass to the
4275 // new constant pool
4276 Array<Method*>* prev_methods = ik->methods();
4277 for (int i = prev_methods->length() - 1; i >= 0; i--) {
4278 Method* method = prev_methods->at(i);
4279 method->set_constants(scratch_class->constants());
4280 }
4281 }
4282 } while (ik != nullptr);
4283 }
4284 #endif
4285
4286 // Replace methods and constantpool
4287 the_class->set_methods(_new_methods);
4288 scratch_class->set_methods(_old_methods); // To prevent potential GCing of the old methods,
4289 // and to be able to undo operation easily.
4290
4291 Array<int>* old_ordering = the_class->method_ordering();
4292 the_class->set_method_ordering(scratch_class->method_ordering());
4293 scratch_class->set_method_ordering(old_ordering);
4294
4295 ConstantPool* old_constants = the_class->constants();
4296 the_class->set_constants(scratch_class->constants());
4297 scratch_class->set_constants(old_constants); // See the previous comment.
4298 #if 0
4299 // We are swapping the guts of "the new class" with the guts of "the
4300 // class". Since the old constant pool has just been attached to "the
4301 // new class", it seems logical to set the pool holder in the old
4302 // constant pool also. However, doing this will change the observable
4303 // class hierarchy for any old methods that are still executing. A
4304 // method can query the identity of its "holder" and this query uses
4305 // the method's constant pool link to find the holder. The change in
4306 // holding class from "the class" to "the new class" can confuse
4307 // things.
4308 //
4309 // Setting the old constant pool's holder will also cause
4310 // verification done during vtable initialization below to fail.
4311 // During vtable initialization, the vtable's class is verified to be
4312 // a subtype of the method's holder. The vtable's class is "the
4313 // class" and the method's holder is gotten from the constant pool
4314 // link in the method itself. For "the class"'s directly implemented
4315 // methods, the method holder is "the class" itself (as gotten from
4316 // the new constant pool). The check works fine in this case. The
4317 // check also works fine for methods inherited from super classes.
4318 //
4319 // Miranda methods are a little more complicated. A miranda method is
4320 // provided by an interface when the class implementing the interface
4321 // does not provide its own method. These interfaces are implemented
4322 // internally as an InstanceKlass. These special instanceKlasses
4323 // share the constant pool of the class that "implements" the
4324 // interface. By sharing the constant pool, the method holder of a
4325 // miranda method is the class that "implements" the interface. In a
4326 // non-redefine situation, the subtype check works fine. However, if
4327 // the old constant pool's pool holder is modified, then the check
4328 // fails because there is no class hierarchy relationship between the
4329 // vtable's class and "the new class".
4330
4331 old_constants->set_pool_holder(scratch_class());
4332 #endif
4333
4334 // track number of methods that are EMCP for add_previous_version() call below
4335 int emcp_method_count = check_methods_and_mark_as_obsolete();
4336 transfer_old_native_function_registrations(the_class);
4337
4338 if (scratch_class->get_cached_class_file() != the_class->get_cached_class_file()) {
4339 // 1. the_class doesn't have a cache yet, scratch_class does have a cache.
4340 // 2. The same class can be present twice in the scratch classes list or there
4341 // are multiple concurrent RetransformClasses calls on different threads.
4342 // the_class and scratch_class have the same cached bytes, but different buffers.
4343 // In such cases we need to deallocate one of the buffers.
4344 // 3. RedefineClasses and the_class has cached bytes from a previous transformation.
4345 // In the case we need to use class bytes from scratch_class.
4346 if (the_class->get_cached_class_file() != nullptr) {
4347 os::free(the_class->get_cached_class_file());
4348 }
4349 the_class->set_cached_class_file(scratch_class->get_cached_class_file());
4350 }
4351
4352 // null out in scratch class to not delete twice. The class to be redefined
4353 // always owns these bytes.
4354 scratch_class->set_cached_class_file(nullptr);
4355
4356 // Replace inner_classes
4357 Array<u2>* old_inner_classes = the_class->inner_classes();
4358 the_class->set_inner_classes(scratch_class->inner_classes());
4359 scratch_class->set_inner_classes(old_inner_classes);
4360
4361 // Initialize the vtable and interface table after
4362 // methods have been rewritten
4363 // no exception should happen here since we explicitly
4364 // do not check loader constraints.
4365 // compare_and_normalize_class_versions has already checked:
4366 // - classloaders unchanged, signatures unchanged
4367 // - all instanceKlasses for redefined classes reused & contents updated
4368 the_class->vtable().initialize_vtable();
4369 the_class->itable().initialize_itable();
4370
4371 // Leave arrays of jmethodIDs and itable index cache unchanged
4372
4373 // Copy the "source debug extension" attribute from new class version
4374 the_class->set_source_debug_extension(
4375 scratch_class->source_debug_extension(),
4376 scratch_class->source_debug_extension() == nullptr ? 0 :
4377 (int)strlen(scratch_class->source_debug_extension()));
4378
4379 // Use of javac -g could be different in the old and the new
4380 if (scratch_class->has_localvariable_table() !=
4381 the_class->has_localvariable_table()) {
4382 the_class->set_has_localvariable_table(scratch_class->has_localvariable_table());
4383 }
4384
4385 swap_annotations(the_class, scratch_class);
4386
4387 // Replace minor version number of class file
4388 u2 old_minor_version = the_class->constants()->minor_version();
4389 the_class->constants()->set_minor_version(scratch_class->constants()->minor_version());
4390 scratch_class->constants()->set_minor_version(old_minor_version);
4391
4392 // Replace major version number of class file
4393 u2 old_major_version = the_class->constants()->major_version();
4394 the_class->constants()->set_major_version(scratch_class->constants()->major_version());
4395 scratch_class->constants()->set_major_version(old_major_version);
4396
4397 // Replace CP indexes for class and name+type of enclosing method
4398 u2 old_class_idx = the_class->enclosing_method_class_index();
4399 u2 old_method_idx = the_class->enclosing_method_method_index();
4400 the_class->set_enclosing_method_indices(
4401 scratch_class->enclosing_method_class_index(),
4402 scratch_class->enclosing_method_method_index());
4403 scratch_class->set_enclosing_method_indices(old_class_idx, old_method_idx);
4404
4405 if (!the_class->has_been_redefined()) {
4406 the_class->set_has_been_redefined();
4407 }
4408
4409 // Scratch class is unloaded but still needs cleaning, and skipping for CDS.
4410 scratch_class->set_is_scratch_class();
4411
4412 // keep track of previous versions of this class
4413 the_class->add_previous_version(scratch_class, emcp_method_count);
4414
4415 _timer_rsc_phase1.stop();
4416 if (log_is_enabled(Info, redefine, class, timer)) {
4417 _timer_rsc_phase2.start();
4418 }
4419
4420 if (the_class->oop_map_cache() != nullptr) {
4421 // Flush references to any obsolete methods from the oop map cache
4422 // so that obsolete methods are not pinned.
4423 the_class->oop_map_cache()->flush_obsolete_entries();
4424 }
4425
4426 increment_class_counter(the_class);
4427
4428 if (EventClassRedefinition::is_enabled()) {
4429 EventClassRedefinition event;
4430 event.set_classModificationCount(java_lang_Class::classRedefinedCount(the_class->java_mirror()));
4431 event.set_redefinedClass(the_class);
4432 event.set_redefinitionId(_id);
4433 event.commit();
4434 }
4435
4436 {
4437 ResourceMark rm(current);
4438 // increment the classRedefinedCount field in the_class and in any
4439 // direct and indirect subclasses of the_class
4440 log_info(redefine, class, load)
4441 ("redefined name=%s, count=%d (avail_mem=" UINT64_FORMAT "K)",
4442 the_class->external_name(), java_lang_Class::classRedefinedCount(the_class->java_mirror()), os::available_memory() >> 10);
4443 Events::log_redefinition(current, "redefined class name=%s, count=%d",
4444 the_class->external_name(),
4445 java_lang_Class::classRedefinedCount(the_class->java_mirror()));
4446
4447 }
4448 _timer_rsc_phase2.stop();
4449
4450 } // end redefine_single_class()
4451
4452
4453 // Increment the classRedefinedCount field in the specific InstanceKlass
4454 // and in all direct and indirect subclasses.
4455 void VM_RedefineClasses::increment_class_counter(InstanceKlass* ik) {
4456 for (ClassHierarchyIterator iter(ik); !iter.done(); iter.next()) {
4457 // Only update instanceKlasses
4458 Klass* sub = iter.klass();
4459 if (sub->is_instance_klass()) {
4460 oop class_mirror = InstanceKlass::cast(sub)->java_mirror();
4461 Klass* class_oop = java_lang_Class::as_Klass(class_mirror);
4462 int new_count = java_lang_Class::classRedefinedCount(class_mirror) + 1;
4463 java_lang_Class::set_classRedefinedCount(class_mirror, new_count);
4464
4465 if (class_oop != _the_class) {
4466 // _the_class count is printed at end of redefine_single_class()
4467 log_debug(redefine, class, subclass)("updated count in subclass=%s to %d", ik->external_name(), new_count);
4468 }
4469 }
4470 }
4471 }
4472
4473 void VM_RedefineClasses::CheckClass::do_klass(Klass* k) {
4474 bool no_old_methods = true; // be optimistic
4475
4476 // Both array and instance classes have vtables.
4477 // a vtable should never contain old or obsolete methods
4478 ResourceMark rm(_thread);
4479 if (k->vtable_length() > 0 &&
4480 !k->vtable().check_no_old_or_obsolete_entries()) {
4481 if (log_is_enabled(Trace, redefine, class, obsolete, metadata)) {
4482 log_trace(redefine, class, obsolete, metadata)
4483 ("klassVtable::check_no_old_or_obsolete_entries failure -- OLD or OBSOLETE method found -- class: %s",
4484 k->signature_name());
4485 k->vtable().dump_vtable();
4486 }
4487 no_old_methods = false;
4488 }
4489
4490 if (k->is_instance_klass()) {
4491 HandleMark hm(_thread);
4492 InstanceKlass *ik = InstanceKlass::cast(k);
4493
4494 // an itable should never contain old or obsolete methods
4495 if (ik->itable_length() > 0 &&
4496 !ik->itable().check_no_old_or_obsolete_entries()) {
4497 if (log_is_enabled(Trace, redefine, class, obsolete, metadata)) {
4498 log_trace(redefine, class, obsolete, metadata)
4499 ("klassItable::check_no_old_or_obsolete_entries failure -- OLD or OBSOLETE method found -- class: %s",
4500 ik->signature_name());
4501 ik->itable().dump_itable();
4502 }
4503 no_old_methods = false;
4504 }
4505
4506 // the constant pool cache should never contain non-deleted old or obsolete methods
4507 if (ik->constants() != nullptr &&
4508 ik->constants()->cache() != nullptr &&
4509 !ik->constants()->cache()->check_no_old_or_obsolete_entries()) {
4510 if (log_is_enabled(Trace, redefine, class, obsolete, metadata)) {
4511 log_trace(redefine, class, obsolete, metadata)
4512 ("cp-cache::check_no_old_or_obsolete_entries failure -- OLD or OBSOLETE method found -- class: %s",
4513 ik->signature_name());
4514 ik->constants()->cache()->dump_cache();
4515 }
4516 no_old_methods = false;
4517 }
4518 }
4519
4520 // print and fail guarantee if old methods are found.
4521 if (!no_old_methods) {
4522 if (log_is_enabled(Trace, redefine, class, obsolete, metadata)) {
4523 dump_methods();
4524 } else {
4525 log_trace(redefine, class)("Use the '-Xlog:redefine+class*:' option "
4526 "to see more info about the following guarantee() failure.");
4527 }
4528 guarantee(false, "OLD and/or OBSOLETE method(s) found");
4529 }
4530 }
4531
4532 u8 VM_RedefineClasses::next_id() {
4533 while (true) {
4534 u8 id = _id_counter;
4535 u8 next_id = id + 1;
4536 u8 result = Atomic::cmpxchg(&_id_counter, id, next_id);
4537 if (result == id) {
4538 return next_id;
4539 }
4540 }
4541 }
4542
4543 void VM_RedefineClasses::dump_methods() {
4544 int j;
4545 log_trace(redefine, class, dump)("_old_methods --");
4546 for (j = 0; j < _old_methods->length(); ++j) {
4547 LogStreamHandle(Trace, redefine, class, dump) log_stream;
4548 Method* m = _old_methods->at(j);
4549 log_stream.print("%4d (%5d) ", j, m->vtable_index());
4550 m->access_flags().print_on(&log_stream);
4551 log_stream.print(" -- ");
4552 m->print_name(&log_stream);
4553 log_stream.cr();
4554 }
4555 log_trace(redefine, class, dump)("_new_methods --");
4556 for (j = 0; j < _new_methods->length(); ++j) {
4557 LogStreamHandle(Trace, redefine, class, dump) log_stream;
4558 Method* m = _new_methods->at(j);
4559 log_stream.print("%4d (%5d) ", j, m->vtable_index());
4560 m->access_flags().print_on(&log_stream);
4561 log_stream.print(" -- ");
4562 m->print_name(&log_stream);
4563 log_stream.cr();
4564 }
4565 log_trace(redefine, class, dump)("_matching_methods --");
4566 for (j = 0; j < _matching_methods_length; ++j) {
4567 LogStreamHandle(Trace, redefine, class, dump) log_stream;
4568 Method* m = _matching_old_methods[j];
4569 log_stream.print("%4d (%5d) ", j, m->vtable_index());
4570 m->access_flags().print_on(&log_stream);
4571 log_stream.print(" -- ");
4572 m->print_name();
4573 log_stream.cr();
4574
4575 m = _matching_new_methods[j];
4576 log_stream.print(" (%5d) ", m->vtable_index());
4577 m->access_flags().print_on(&log_stream);
4578 log_stream.cr();
4579 }
4580 log_trace(redefine, class, dump)("_deleted_methods --");
4581 for (j = 0; j < _deleted_methods_length; ++j) {
4582 LogStreamHandle(Trace, redefine, class, dump) log_stream;
4583 Method* m = _deleted_methods[j];
4584 log_stream.print("%4d (%5d) ", j, m->vtable_index());
4585 m->access_flags().print_on(&log_stream);
4586 log_stream.print(" -- ");
4587 m->print_name(&log_stream);
4588 log_stream.cr();
4589 }
4590 log_trace(redefine, class, dump)("_added_methods --");
4591 for (j = 0; j < _added_methods_length; ++j) {
4592 LogStreamHandle(Trace, redefine, class, dump) log_stream;
4593 Method* m = _added_methods[j];
4594 log_stream.print("%4d (%5d) ", j, m->vtable_index());
4595 m->access_flags().print_on(&log_stream);
4596 log_stream.print(" -- ");
4597 m->print_name(&log_stream);
4598 log_stream.cr();
4599 }
4600 }
4601
4602 void VM_RedefineClasses::print_on_error(outputStream* st) const {
4603 VM_Operation::print_on_error(st);
4604 if (_the_class != nullptr) {
4605 ResourceMark rm;
4606 st->print_cr(", redefining class %s", _the_class->external_name());
4607 }
4608 }