1 /*
2 * Copyright (c) 2003, 2025, 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 "cds/cdsConfig.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 (CDSConfig::is_using_archive()) {
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 u2 old_flags = the_class->access_flags().as_class_flags();
1007 u2 new_flags = scratch_class->access_flags().as_class_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_field_flags();
1042 new_flags = new_fs.access_flags().as_field_flags();
1043 if (old_flags != new_flags) {
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 = k_old_method->access_flags().as_method_flags();
1149 new_flags = k_new_method->access_flags().as_method_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());)
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
1365 // Set redefined class handle in JvmtiThreadState class.
1366 // This redefined class is sent to agent event handler for class file
1367 // load hook event.
1368 state->set_class_being_redefined(the_class, _class_load_kind);
1369
1370 JavaThread* THREAD = current; // For exception macros.
1371 ExceptionMark em(THREAD);
1372 Handle protection_domain(THREAD, the_class->protection_domain());
1373 ClassLoadInfo cl_info(protection_domain);
1374 // Parse and create a class from the bytes, but this class isn't added
1375 // to the dictionary, so do not call resolve_from_stream.
1376 InstanceKlass* scratch_class = KlassFactory::create_from_stream(&st,
1377 the_class->name(),
1378 the_class->class_loader_data(),
1379 cl_info,
1380 THREAD);
1381
1382 // Clear class_being_redefined just to be sure.
1383 state->clear_class_being_redefined();
1384
1385 // TODO: if this is retransform, and nothing changed we can skip it
1386
1387 // Need to clean up allocated InstanceKlass if there's an error so assign
1388 // the result here. Caller deallocates all the scratch classes in case of
1389 // an error.
1390 _scratch_classes[i] = scratch_class;
1391
1392 if (HAS_PENDING_EXCEPTION) {
1393 Symbol* ex_name = PENDING_EXCEPTION->klass()->name();
1394 log_info(redefine, class, load, exceptions)("create_from_stream exception: '%s'", ex_name->as_C_string());
1395 CLEAR_PENDING_EXCEPTION;
1396
1397 if (ex_name == vmSymbols::java_lang_UnsupportedClassVersionError()) {
1398 return JVMTI_ERROR_UNSUPPORTED_VERSION;
1399 } else if (ex_name == vmSymbols::java_lang_ClassFormatError()) {
1400 return JVMTI_ERROR_INVALID_CLASS_FORMAT;
1401 } else if (ex_name == vmSymbols::java_lang_ClassCircularityError()) {
1402 return JVMTI_ERROR_CIRCULAR_CLASS_DEFINITION;
1403 } else if (ex_name == vmSymbols::java_lang_NoClassDefFoundError()) {
1404 // The message will be "XXX (wrong name: YYY)"
1405 return JVMTI_ERROR_NAMES_DONT_MATCH;
1406 } else if (ex_name == vmSymbols::java_lang_OutOfMemoryError()) {
1407 return JVMTI_ERROR_OUT_OF_MEMORY;
1408 } else { // Just in case more exceptions can be thrown..
1409 return JVMTI_ERROR_FAILS_VERIFICATION;
1410 }
1411 }
1412
1413 // Ensure class is linked before redefine
1414 if (!the_class->is_linked()) {
1415 the_class->link_class(THREAD);
1416 if (HAS_PENDING_EXCEPTION) {
1417 Symbol* ex_name = PENDING_EXCEPTION->klass()->name();
1418 oop message = java_lang_Throwable::message(PENDING_EXCEPTION);
1419 if (message != nullptr) {
1420 char* ex_msg = java_lang_String::as_utf8_string(message);
1421 log_info(redefine, class, load, exceptions)("link_class exception: '%s %s'",
1422 ex_name->as_C_string(), ex_msg);
1423 } else {
1424 log_info(redefine, class, load, exceptions)("link_class exception: '%s'",
1425 ex_name->as_C_string());
1426 }
1427 CLEAR_PENDING_EXCEPTION;
1428 if (ex_name == vmSymbols::java_lang_OutOfMemoryError()) {
1429 return JVMTI_ERROR_OUT_OF_MEMORY;
1430 } else if (ex_name == vmSymbols::java_lang_NoClassDefFoundError()) {
1431 return JVMTI_ERROR_INVALID_CLASS;
1432 } else {
1433 return JVMTI_ERROR_INTERNAL;
1434 }
1435 }
1436 }
1437
1438 // Do the validity checks in compare_and_normalize_class_versions()
1439 // before verifying the byte codes. By doing these checks first, we
1440 // limit the number of functions that require redirection from
1441 // the_class to scratch_class. In particular, we don't have to
1442 // modify JNI GetSuperclass() and thus won't change its performance.
1443 jvmtiError res = compare_and_normalize_class_versions(the_class,
1444 scratch_class);
1445 if (res != JVMTI_ERROR_NONE) {
1446 return res;
1447 }
1448
1449 // verify what the caller passed us
1450 {
1451 // The bug 6214132 caused the verification to fail.
1452 // Information about the_class and scratch_class is temporarily
1453 // recorded into jvmtiThreadState. This data is used to redirect
1454 // the_class to scratch_class in the JVM_* functions called by the
1455 // verifier. Please, refer to jvmtiThreadState.hpp for the detailed
1456 // description.
1457 RedefineVerifyMark rvm(the_class, scratch_class, state);
1458 Verifier::verify(scratch_class, true, THREAD);
1459 }
1460
1461 if (HAS_PENDING_EXCEPTION) {
1462 Symbol* ex_name = PENDING_EXCEPTION->klass()->name();
1463 log_info(redefine, class, load, exceptions)("verify_byte_codes exception: '%s'", ex_name->as_C_string());
1464 CLEAR_PENDING_EXCEPTION;
1465 if (ex_name == vmSymbols::java_lang_OutOfMemoryError()) {
1466 return JVMTI_ERROR_OUT_OF_MEMORY;
1467 } else {
1468 // tell the caller the bytecodes are bad
1469 return JVMTI_ERROR_FAILS_VERIFICATION;
1470 }
1471 }
1472
1473 res = merge_cp_and_rewrite(the_class, scratch_class, THREAD);
1474 if (HAS_PENDING_EXCEPTION) {
1475 Symbol* ex_name = PENDING_EXCEPTION->klass()->name();
1476 log_info(redefine, class, load, exceptions)("merge_cp_and_rewrite exception: '%s'", ex_name->as_C_string());
1477 CLEAR_PENDING_EXCEPTION;
1478 if (ex_name == vmSymbols::java_lang_OutOfMemoryError()) {
1479 return JVMTI_ERROR_OUT_OF_MEMORY;
1480 } else {
1481 return JVMTI_ERROR_INTERNAL;
1482 }
1483 }
1484
1485 #ifdef ASSERT
1486 {
1487 // verify what we have done during constant pool merging
1488 {
1489 RedefineVerifyMark rvm(the_class, scratch_class, state);
1490 Verifier::verify(scratch_class, true, THREAD);
1491 }
1492
1493 if (HAS_PENDING_EXCEPTION) {
1494 Symbol* ex_name = PENDING_EXCEPTION->klass()->name();
1495 log_info(redefine, class, load, exceptions)
1496 ("verify_byte_codes post merge-CP exception: '%s'", ex_name->as_C_string());
1497 CLEAR_PENDING_EXCEPTION;
1498 if (ex_name == vmSymbols::java_lang_OutOfMemoryError()) {
1499 return JVMTI_ERROR_OUT_OF_MEMORY;
1500 } else {
1501 // tell the caller that constant pool merging screwed up
1502 return JVMTI_ERROR_INTERNAL;
1503 }
1504 }
1505 }
1506 #endif // ASSERT
1507
1508 Rewriter::rewrite(scratch_class, THREAD);
1509 if (!HAS_PENDING_EXCEPTION) {
1510 scratch_class->link_methods(THREAD);
1511 }
1512 if (HAS_PENDING_EXCEPTION) {
1513 Symbol* ex_name = PENDING_EXCEPTION->klass()->name();
1514 log_info(redefine, class, load, exceptions)
1515 ("Rewriter::rewrite or link_methods exception: '%s'", ex_name->as_C_string());
1516 CLEAR_PENDING_EXCEPTION;
1517 if (ex_name == vmSymbols::java_lang_OutOfMemoryError()) {
1518 return JVMTI_ERROR_OUT_OF_MEMORY;
1519 } else {
1520 return JVMTI_ERROR_INTERNAL;
1521 }
1522 }
1523
1524 log_debug(redefine, class, load)
1525 ("loaded name=%s (avail_mem=" UINT64_FORMAT "K)", the_class->external_name(), os::available_memory() >> 10);
1526 }
1527
1528 return JVMTI_ERROR_NONE;
1529 }
1530
1531
1532 // Map old_index to new_index as needed. scratch_cp is only needed
1533 // for log calls.
1534 void VM_RedefineClasses::map_index(const constantPoolHandle& scratch_cp,
1535 int old_index, int new_index) {
1536 if (find_new_index(old_index) != 0) {
1537 // old_index is already mapped
1538 return;
1539 }
1540
1541 if (old_index == new_index) {
1542 // no mapping is needed
1543 return;
1544 }
1545
1546 _index_map_p->at_put(old_index, new_index);
1547 _index_map_count++;
1548
1549 log_trace(redefine, class, constantpool)
1550 ("mapped tag %d at index %d to %d", scratch_cp->tag_at(old_index).value(), old_index, new_index);
1551 } // end map_index()
1552
1553
1554 // Map old_index to new_index as needed.
1555 void VM_RedefineClasses::map_operand_index(int old_index, int new_index) {
1556 if (find_new_operand_index(old_index) != -1) {
1557 // old_index is already mapped
1558 return;
1559 }
1560
1561 if (old_index == new_index) {
1562 // no mapping is needed
1563 return;
1564 }
1565
1566 _operands_index_map_p->at_put(old_index, new_index);
1567 _operands_index_map_count++;
1568
1569 log_trace(redefine, class, constantpool)("mapped bootstrap specifier at index %d to %d", old_index, new_index);
1570 } // end map_index()
1571
1572
1573 // Merge old_cp and scratch_cp and return the results of the merge via
1574 // merge_cp_p. The number of entries in *merge_cp_p is returned via
1575 // merge_cp_length_p. The entries in old_cp occupy the same locations
1576 // in *merge_cp_p. Also creates a map of indices from entries in
1577 // scratch_cp to the corresponding entry in *merge_cp_p. Index map
1578 // entries are only created for entries in scratch_cp that occupy a
1579 // different location in *merged_cp_p.
1580 bool VM_RedefineClasses::merge_constant_pools(const constantPoolHandle& old_cp,
1581 const constantPoolHandle& scratch_cp, constantPoolHandle *merge_cp_p,
1582 int *merge_cp_length_p, TRAPS) {
1583
1584 if (merge_cp_p == nullptr) {
1585 assert(false, "caller must provide scratch constantPool");
1586 return false; // robustness
1587 }
1588 if (merge_cp_length_p == nullptr) {
1589 assert(false, "caller must provide scratch CP length");
1590 return false; // robustness
1591 }
1592 // Worst case we need old_cp->length() + scratch_cp()->length(),
1593 // but the caller might be smart so make sure we have at least
1594 // the minimum.
1595 if ((*merge_cp_p)->length() < old_cp->length()) {
1596 assert(false, "merge area too small");
1597 return false; // robustness
1598 }
1599
1600 log_info(redefine, class, constantpool)("old_cp_len=%d, scratch_cp_len=%d", old_cp->length(), scratch_cp->length());
1601
1602 {
1603 // Pass 0:
1604 // The old_cp is copied to *merge_cp_p; this means that any code
1605 // using old_cp does not have to change. This work looks like a
1606 // perfect fit for ConstantPool*::copy_cp_to(), but we need to
1607 // handle one special case:
1608 // - revert JVM_CONSTANT_Class to JVM_CONSTANT_UnresolvedClass
1609 // This will make verification happy.
1610
1611 int old_i; // index into old_cp
1612
1613 // index zero (0) is not used in constantPools
1614 for (old_i = 1; old_i < old_cp->length(); old_i++) {
1615 // leave debugging crumb
1616 jbyte old_tag = old_cp->tag_at(old_i).value();
1617 switch (old_tag) {
1618 case JVM_CONSTANT_Class:
1619 case JVM_CONSTANT_UnresolvedClass:
1620 // revert the copy to JVM_CONSTANT_UnresolvedClass
1621 // May be resolving while calling this so do the same for
1622 // JVM_CONSTANT_UnresolvedClass (klass_name_at() deals with transition)
1623 (*merge_cp_p)->temp_unresolved_klass_at_put(old_i,
1624 old_cp->klass_name_index_at(old_i));
1625 break;
1626
1627 case JVM_CONSTANT_Double:
1628 case JVM_CONSTANT_Long:
1629 // just copy the entry to *merge_cp_p, but double and long take
1630 // two constant pool entries
1631 ConstantPool::copy_entry_to(old_cp, old_i, *merge_cp_p, old_i);
1632 old_i++;
1633 break;
1634
1635 default:
1636 // just copy the entry to *merge_cp_p
1637 ConstantPool::copy_entry_to(old_cp, old_i, *merge_cp_p, old_i);
1638 break;
1639 }
1640 } // end for each old_cp entry
1641
1642 ConstantPool::copy_operands(old_cp, *merge_cp_p, CHECK_false);
1643 (*merge_cp_p)->extend_operands(scratch_cp, CHECK_false);
1644
1645 // We don't need to sanity check that *merge_cp_length_p is within
1646 // *merge_cp_p bounds since we have the minimum on-entry check above.
1647 (*merge_cp_length_p) = old_i;
1648 }
1649
1650 // merge_cp_len should be the same as old_cp->length() at this point
1651 // so this trace message is really a "warm-and-breathing" message.
1652 log_debug(redefine, class, constantpool)("after pass 0: merge_cp_len=%d", *merge_cp_length_p);
1653
1654 int scratch_i; // index into scratch_cp
1655 {
1656 // Pass 1a:
1657 // Compare scratch_cp entries to the old_cp entries that we have
1658 // already copied to *merge_cp_p. In this pass, we are eliminating
1659 // exact duplicates (matching entry at same index) so we only
1660 // compare entries in the common indice range.
1661 int increment = 1;
1662 int pass1a_length = MIN2(old_cp->length(), scratch_cp->length());
1663 for (scratch_i = 1; scratch_i < pass1a_length; scratch_i += increment) {
1664 switch (scratch_cp->tag_at(scratch_i).value()) {
1665 case JVM_CONSTANT_Double:
1666 case JVM_CONSTANT_Long:
1667 // double and long take two constant pool entries
1668 increment = 2;
1669 break;
1670
1671 default:
1672 increment = 1;
1673 break;
1674 }
1675
1676 bool match = scratch_cp->compare_entry_to(scratch_i, *merge_cp_p, scratch_i);
1677 if (match) {
1678 // found a match at the same index so nothing more to do
1679 continue;
1680 }
1681
1682 int found_i = scratch_cp->find_matching_entry(scratch_i, *merge_cp_p);
1683 if (found_i != 0) {
1684 guarantee(found_i != scratch_i,
1685 "compare_entry_to() and find_matching_entry() do not agree");
1686
1687 // Found a matching entry somewhere else in *merge_cp_p so
1688 // just need a mapping entry.
1689 map_index(scratch_cp, scratch_i, found_i);
1690 continue;
1691 }
1692
1693 // No match found so we have to append this entry and any unique
1694 // referenced entries to *merge_cp_p.
1695 append_entry(scratch_cp, scratch_i, merge_cp_p, merge_cp_length_p);
1696 }
1697 }
1698
1699 log_debug(redefine, class, constantpool)
1700 ("after pass 1a: merge_cp_len=%d, scratch_i=%d, index_map_len=%d",
1701 *merge_cp_length_p, scratch_i, _index_map_count);
1702
1703 if (scratch_i < scratch_cp->length()) {
1704 // Pass 1b:
1705 // old_cp is smaller than scratch_cp so there are entries in
1706 // scratch_cp that we have not yet processed. We take care of
1707 // those now.
1708 int increment = 1;
1709 for (; scratch_i < scratch_cp->length(); scratch_i += increment) {
1710 switch (scratch_cp->tag_at(scratch_i).value()) {
1711 case JVM_CONSTANT_Double:
1712 case JVM_CONSTANT_Long:
1713 // double and long take two constant pool entries
1714 increment = 2;
1715 break;
1716
1717 default:
1718 increment = 1;
1719 break;
1720 }
1721
1722 int found_i =
1723 scratch_cp->find_matching_entry(scratch_i, *merge_cp_p);
1724 if (found_i != 0) {
1725 // Found a matching entry somewhere else in *merge_cp_p so
1726 // just need a mapping entry.
1727 map_index(scratch_cp, scratch_i, found_i);
1728 continue;
1729 }
1730
1731 // No match found so we have to append this entry and any unique
1732 // referenced entries to *merge_cp_p.
1733 append_entry(scratch_cp, scratch_i, merge_cp_p, merge_cp_length_p);
1734 }
1735
1736 log_debug(redefine, class, constantpool)
1737 ("after pass 1b: merge_cp_len=%d, scratch_i=%d, index_map_len=%d",
1738 *merge_cp_length_p, scratch_i, _index_map_count);
1739 }
1740 finalize_operands_merge(*merge_cp_p, CHECK_false);
1741
1742 return true;
1743 } // end merge_constant_pools()
1744
1745
1746 // Scoped object to clean up the constant pool(s) created for merging
1747 class MergeCPCleaner {
1748 ClassLoaderData* _loader_data;
1749 ConstantPool* _cp;
1750 ConstantPool* _scratch_cp;
1751 public:
1752 MergeCPCleaner(ClassLoaderData* loader_data, ConstantPool* merge_cp) :
1753 _loader_data(loader_data), _cp(merge_cp), _scratch_cp(nullptr) {}
1754 ~MergeCPCleaner() {
1755 _loader_data->add_to_deallocate_list(_cp);
1756 if (_scratch_cp != nullptr) {
1757 _loader_data->add_to_deallocate_list(_scratch_cp);
1758 }
1759 }
1760 void add_scratch_cp(ConstantPool* scratch_cp) { _scratch_cp = scratch_cp; }
1761 };
1762
1763 // Merge constant pools between the_class and scratch_class and
1764 // potentially rewrite bytecodes in scratch_class to use the merged
1765 // constant pool.
1766 jvmtiError VM_RedefineClasses::merge_cp_and_rewrite(
1767 InstanceKlass* the_class, InstanceKlass* scratch_class,
1768 TRAPS) {
1769 // worst case merged constant pool length is old and new combined
1770 int merge_cp_length = the_class->constants()->length()
1771 + scratch_class->constants()->length();
1772
1773 // Constant pools are not easily reused so we allocate a new one
1774 // each time.
1775 // merge_cp is created unsafe for concurrent GC processing. It
1776 // should be marked safe before discarding it. Even though
1777 // garbage, if it crosses a card boundary, it may be scanned
1778 // in order to find the start of the first complete object on the card.
1779 ClassLoaderData* loader_data = the_class->class_loader_data();
1780 ConstantPool* merge_cp_oop =
1781 ConstantPool::allocate(loader_data,
1782 merge_cp_length,
1783 CHECK_(JVMTI_ERROR_OUT_OF_MEMORY));
1784 MergeCPCleaner cp_cleaner(loader_data, merge_cp_oop);
1785
1786 HandleMark hm(THREAD); // make sure handles are cleared before
1787 // MergeCPCleaner clears out merge_cp_oop
1788 constantPoolHandle merge_cp(THREAD, merge_cp_oop);
1789
1790 // Get constants() from the old class because it could have been rewritten
1791 // while we were at a safepoint allocating a new constant pool.
1792 constantPoolHandle old_cp(THREAD, the_class->constants());
1793 constantPoolHandle scratch_cp(THREAD, scratch_class->constants());
1794
1795 // If the length changed, the class was redefined out from under us. Return
1796 // an error.
1797 if (merge_cp_length != the_class->constants()->length()
1798 + scratch_class->constants()->length()) {
1799 return JVMTI_ERROR_INTERNAL;
1800 }
1801
1802 // Update the version number of the constant pools (may keep scratch_cp)
1803 merge_cp->increment_and_save_version(old_cp->version());
1804 scratch_cp->increment_and_save_version(old_cp->version());
1805
1806 ResourceMark rm(THREAD);
1807 _index_map_count = 0;
1808 _index_map_p = new intArray(scratch_cp->length(), scratch_cp->length(), -1);
1809
1810 _operands_cur_length = ConstantPool::operand_array_length(old_cp->operands());
1811 _operands_index_map_count = 0;
1812 int operands_index_map_len = ConstantPool::operand_array_length(scratch_cp->operands());
1813 _operands_index_map_p = new intArray(operands_index_map_len, operands_index_map_len, -1);
1814
1815 // reference to the cp holder is needed for copy_operands()
1816 merge_cp->set_pool_holder(scratch_class);
1817 bool result = merge_constant_pools(old_cp, scratch_cp, &merge_cp,
1818 &merge_cp_length, THREAD);
1819 merge_cp->set_pool_holder(nullptr);
1820
1821 if (!result) {
1822 // The merge can fail due to memory allocation failure or due
1823 // to robustness checks.
1824 return JVMTI_ERROR_INTERNAL;
1825 }
1826
1827 // ensure merged constant pool size does not overflow u2
1828 if (merge_cp_length > 0xFFFF) {
1829 log_warning(redefine, class, constantpool)("Merged constant pool overflow: %d entries", merge_cp_length);
1830 return JVMTI_ERROR_INTERNAL;
1831 }
1832
1833 // Set dynamic constants attribute from the original CP.
1834 if (old_cp->has_dynamic_constant()) {
1835 scratch_cp->set_has_dynamic_constant();
1836 }
1837
1838 log_info(redefine, class, constantpool)("merge_cp_len=%d, index_map_len=%d", merge_cp_length, _index_map_count);
1839
1840 if (_index_map_count == 0) {
1841 // there is nothing to map between the new and merged constant pools
1842
1843 // Copy attributes from scratch_cp to merge_cp
1844 merge_cp->copy_fields(scratch_cp());
1845
1846 if (old_cp->length() == scratch_cp->length()) {
1847 // The old and new constant pools are the same length and the
1848 // index map is empty. This means that the three constant pools
1849 // are equivalent (but not the same). Unfortunately, the new
1850 // constant pool has not gone through link resolution nor have
1851 // the new class bytecodes gone through constant pool cache
1852 // rewriting so we can't use the old constant pool with the new
1853 // class.
1854
1855 // toss the merged constant pool at return
1856 } else if (old_cp->length() < scratch_cp->length()) {
1857 // The old constant pool has fewer entries than the new constant
1858 // pool and the index map is empty. This means the new constant
1859 // pool is a superset of the old constant pool. However, the old
1860 // class bytecodes have already gone through constant pool cache
1861 // rewriting so we can't use the new constant pool with the old
1862 // class.
1863
1864 // toss the merged constant pool at return
1865 } else {
1866 // The old constant pool has more entries than the new constant
1867 // pool and the index map is empty. This means that both the old
1868 // and merged constant pools are supersets of the new constant
1869 // pool.
1870
1871 // Replace the new constant pool with a shrunken copy of the
1872 // merged constant pool
1873 set_new_constant_pool(loader_data, scratch_class, merge_cp, merge_cp_length,
1874 CHECK_(JVMTI_ERROR_OUT_OF_MEMORY));
1875 // The new constant pool replaces scratch_cp so have cleaner clean it up.
1876 // It can't be cleaned up while there are handles to it.
1877 cp_cleaner.add_scratch_cp(scratch_cp());
1878 }
1879 } else {
1880 if (log_is_enabled(Trace, redefine, class, constantpool)) {
1881 // don't want to loop unless we are tracing
1882 int count = 0;
1883 for (int i = 1; i < _index_map_p->length(); i++) {
1884 int value = _index_map_p->at(i);
1885
1886 if (value != -1) {
1887 log_trace(redefine, class, constantpool)("index_map[%d]: old=%d new=%d", count, i, value);
1888 count++;
1889 }
1890 }
1891 }
1892
1893 // We have entries mapped between the new and merged constant pools
1894 // so we have to rewrite some constant pool references.
1895 if (!rewrite_cp_refs(scratch_class)) {
1896 return JVMTI_ERROR_INTERNAL;
1897 }
1898
1899 // Copy attributes from scratch_cp to merge_cp (should be done after rewrite_cp_refs())
1900 merge_cp->copy_fields(scratch_cp());
1901
1902 // Replace the new constant pool with a shrunken copy of the
1903 // merged constant pool so now the rewritten bytecodes have
1904 // valid references; the previous new constant pool will get
1905 // GCed.
1906 set_new_constant_pool(loader_data, scratch_class, merge_cp, merge_cp_length,
1907 CHECK_(JVMTI_ERROR_OUT_OF_MEMORY));
1908 // The new constant pool replaces scratch_cp so have cleaner clean it up.
1909 // It can't be cleaned up while there are handles to it.
1910 cp_cleaner.add_scratch_cp(scratch_cp());
1911 }
1912
1913 return JVMTI_ERROR_NONE;
1914 } // end merge_cp_and_rewrite()
1915
1916
1917 // Rewrite constant pool references in klass scratch_class.
1918 bool VM_RedefineClasses::rewrite_cp_refs(InstanceKlass* scratch_class) {
1919
1920 // rewrite constant pool references in the nest attributes:
1921 if (!rewrite_cp_refs_in_nest_attributes(scratch_class)) {
1922 // propagate failure back to caller
1923 return false;
1924 }
1925
1926 // rewrite constant pool references in the Record attribute:
1927 if (!rewrite_cp_refs_in_record_attribute(scratch_class)) {
1928 // propagate failure back to caller
1929 return false;
1930 }
1931
1932 // rewrite constant pool references in the PermittedSubclasses attribute:
1933 if (!rewrite_cp_refs_in_permitted_subclasses_attribute(scratch_class)) {
1934 // propagate failure back to caller
1935 return false;
1936 }
1937
1938 // rewrite constant pool references in the LoadableDescriptors attribute:
1939 if (!rewrite_cp_refs_in_loadable_descriptors_attribute(scratch_class)) {
1940 // propagate failure back to caller
1941 return false;
1942 }
1943
1944 // rewrite constant pool references in the methods:
1945 if (!rewrite_cp_refs_in_methods(scratch_class)) {
1946 // propagate failure back to caller
1947 return false;
1948 }
1949
1950 // rewrite constant pool references in the class_annotations:
1951 if (!rewrite_cp_refs_in_class_annotations(scratch_class)) {
1952 // propagate failure back to caller
1953 return false;
1954 }
1955
1956 // rewrite constant pool references in the fields_annotations:
1957 if (!rewrite_cp_refs_in_fields_annotations(scratch_class)) {
1958 // propagate failure back to caller
1959 return false;
1960 }
1961
1962 // rewrite constant pool references in the methods_annotations:
1963 if (!rewrite_cp_refs_in_methods_annotations(scratch_class)) {
1964 // propagate failure back to caller
1965 return false;
1966 }
1967
1968 // rewrite constant pool references in the methods_parameter_annotations:
1969 if (!rewrite_cp_refs_in_methods_parameter_annotations(scratch_class)) {
1970 // propagate failure back to caller
1971 return false;
1972 }
1973
1974 // rewrite constant pool references in the methods_default_annotations:
1975 if (!rewrite_cp_refs_in_methods_default_annotations(scratch_class)) {
1976 // propagate failure back to caller
1977 return false;
1978 }
1979
1980 // rewrite constant pool references in the class_type_annotations:
1981 if (!rewrite_cp_refs_in_class_type_annotations(scratch_class)) {
1982 // propagate failure back to caller
1983 return false;
1984 }
1985
1986 // rewrite constant pool references in the fields_type_annotations:
1987 if (!rewrite_cp_refs_in_fields_type_annotations(scratch_class)) {
1988 // propagate failure back to caller
1989 return false;
1990 }
1991
1992 // rewrite constant pool references in the methods_type_annotations:
1993 if (!rewrite_cp_refs_in_methods_type_annotations(scratch_class)) {
1994 // propagate failure back to caller
1995 return false;
1996 }
1997
1998 // There can be type annotations in the Code part of a method_info attribute.
1999 // These annotations are not accessible, even by reflection.
2000 // Currently they are not even parsed by the ClassFileParser.
2001 // If runtime access is added they will also need to be rewritten.
2002
2003 // rewrite source file name index:
2004 u2 source_file_name_idx = scratch_class->source_file_name_index();
2005 if (source_file_name_idx != 0) {
2006 u2 new_source_file_name_idx = find_new_index(source_file_name_idx);
2007 if (new_source_file_name_idx != 0) {
2008 scratch_class->set_source_file_name_index(new_source_file_name_idx);
2009 }
2010 }
2011
2012 // rewrite class generic signature index:
2013 u2 generic_signature_index = scratch_class->generic_signature_index();
2014 if (generic_signature_index != 0) {
2015 u2 new_generic_signature_index = find_new_index(generic_signature_index);
2016 if (new_generic_signature_index != 0) {
2017 scratch_class->set_generic_signature_index(new_generic_signature_index);
2018 }
2019 }
2020
2021 return true;
2022 } // end rewrite_cp_refs()
2023
2024 // Rewrite constant pool references in the NestHost and NestMembers attributes.
2025 bool VM_RedefineClasses::rewrite_cp_refs_in_nest_attributes(
2026 InstanceKlass* scratch_class) {
2027
2028 u2 cp_index = scratch_class->nest_host_index();
2029 if (cp_index != 0) {
2030 scratch_class->set_nest_host_index(find_new_index(cp_index));
2031 }
2032 Array<u2>* nest_members = scratch_class->nest_members();
2033 for (int i = 0; i < nest_members->length(); i++) {
2034 u2 cp_index = nest_members->at(i);
2035 nest_members->at_put(i, find_new_index(cp_index));
2036 }
2037 return true;
2038 }
2039
2040 // Rewrite constant pool references in the Record attribute.
2041 bool VM_RedefineClasses::rewrite_cp_refs_in_record_attribute(InstanceKlass* scratch_class) {
2042 Array<RecordComponent*>* components = scratch_class->record_components();
2043 if (components != nullptr) {
2044 for (int i = 0; i < components->length(); i++) {
2045 RecordComponent* component = components->at(i);
2046 u2 cp_index = component->name_index();
2047 component->set_name_index(find_new_index(cp_index));
2048 cp_index = component->descriptor_index();
2049 component->set_descriptor_index(find_new_index(cp_index));
2050 cp_index = component->generic_signature_index();
2051 if (cp_index != 0) {
2052 component->set_generic_signature_index(find_new_index(cp_index));
2053 }
2054
2055 AnnotationArray* annotations = component->annotations();
2056 if (annotations != nullptr && annotations->length() != 0) {
2057 int byte_i = 0; // byte index into annotations
2058 if (!rewrite_cp_refs_in_annotations_typeArray(annotations, byte_i)) {
2059 log_debug(redefine, class, annotation)("bad record_component_annotations at %d", i);
2060 // propagate failure back to caller
2061 return false;
2062 }
2063 }
2064
2065 AnnotationArray* type_annotations = component->type_annotations();
2066 if (type_annotations != nullptr && type_annotations->length() != 0) {
2067 int byte_i = 0; // byte index into annotations
2068 if (!rewrite_cp_refs_in_annotations_typeArray(type_annotations, byte_i)) {
2069 log_debug(redefine, class, annotation)("bad record_component_type_annotations at %d", i);
2070 // propagate failure back to caller
2071 return false;
2072 }
2073 }
2074 }
2075 }
2076 return true;
2077 }
2078
2079 // Rewrite constant pool references in the PermittedSubclasses attribute.
2080 bool VM_RedefineClasses::rewrite_cp_refs_in_permitted_subclasses_attribute(
2081 InstanceKlass* scratch_class) {
2082
2083 Array<u2>* permitted_subclasses = scratch_class->permitted_subclasses();
2084 assert(permitted_subclasses != nullptr, "unexpected null permitted_subclasses");
2085 for (int i = 0; i < permitted_subclasses->length(); i++) {
2086 u2 cp_index = permitted_subclasses->at(i);
2087 permitted_subclasses->at_put(i, find_new_index(cp_index));
2088 }
2089 return true;
2090 }
2091
2092 // Rewrite constant pool references in the LoadableDescriptors attribute.
2093 bool VM_RedefineClasses::rewrite_cp_refs_in_loadable_descriptors_attribute(
2094 InstanceKlass* scratch_class) {
2095
2096 Array<u2>* loadable_descriptors = scratch_class->loadable_descriptors();
2097 assert(loadable_descriptors != nullptr, "unexpected null loadable_descriptors");
2098 for (int i = 0; i < loadable_descriptors->length(); i++) {
2099 u2 cp_index = loadable_descriptors->at(i);
2100 loadable_descriptors->at_put(i, find_new_index(cp_index));
2101 }
2102 return true;
2103 }
2104
2105 // Rewrite constant pool references in the methods.
2106 bool VM_RedefineClasses::rewrite_cp_refs_in_methods(InstanceKlass* scratch_class) {
2107
2108 Array<Method*>* methods = scratch_class->methods();
2109
2110 if (methods == nullptr || methods->length() == 0) {
2111 // no methods so nothing to do
2112 return true;
2113 }
2114
2115 JavaThread* THREAD = JavaThread::current(); // For exception macros.
2116 ExceptionMark em(THREAD);
2117
2118 // rewrite constant pool references in the methods:
2119 for (int i = methods->length() - 1; i >= 0; i--) {
2120 methodHandle method(THREAD, methods->at(i));
2121 methodHandle new_method;
2122 rewrite_cp_refs_in_method(method, &new_method, THREAD);
2123 if (!new_method.is_null()) {
2124 // the method has been replaced so save the new method version
2125 // even in the case of an exception. original method is on the
2126 // deallocation list.
2127 methods->at_put(i, new_method());
2128 }
2129 if (HAS_PENDING_EXCEPTION) {
2130 Symbol* ex_name = PENDING_EXCEPTION->klass()->name();
2131 log_info(redefine, class, load, exceptions)("rewrite_cp_refs_in_method exception: '%s'", ex_name->as_C_string());
2132 // Need to clear pending exception here as the super caller sets
2133 // the JVMTI_ERROR_INTERNAL if the returned value is false.
2134 CLEAR_PENDING_EXCEPTION;
2135 return false;
2136 }
2137 }
2138
2139 return true;
2140 }
2141
2142
2143 // Rewrite constant pool references in the specific method. This code
2144 // was adapted from Rewriter::rewrite_method().
2145 void VM_RedefineClasses::rewrite_cp_refs_in_method(methodHandle method,
2146 methodHandle *new_method_p, TRAPS) {
2147
2148 *new_method_p = methodHandle(); // default is no new method
2149
2150 // We cache a pointer to the bytecodes here in code_base. If GC
2151 // moves the Method*, then the bytecodes will also move which
2152 // will likely cause a crash. We create a NoSafepointVerifier
2153 // object to detect whether we pass a possible safepoint in this
2154 // code block.
2155 NoSafepointVerifier nsv;
2156
2157 // Bytecodes and their length
2158 address code_base = method->code_base();
2159 int code_length = method->code_size();
2160
2161 int bc_length;
2162 for (int bci = 0; bci < code_length; bci += bc_length) {
2163 address bcp = code_base + bci;
2164 Bytecodes::Code c = (Bytecodes::Code)(*bcp);
2165
2166 bc_length = Bytecodes::length_for(c);
2167 if (bc_length == 0) {
2168 // More complicated bytecodes report a length of zero so
2169 // we have to try again a slightly different way.
2170 bc_length = Bytecodes::length_at(method(), bcp);
2171 }
2172
2173 assert(bc_length != 0, "impossible bytecode length");
2174
2175 switch (c) {
2176 case Bytecodes::_ldc:
2177 {
2178 u1 cp_index = *(bcp + 1);
2179 u2 new_index = find_new_index(cp_index);
2180
2181 if (StressLdcRewrite && new_index == 0) {
2182 // If we are stressing ldc -> ldc_w rewriting, then we
2183 // always need a new_index value.
2184 new_index = cp_index;
2185 }
2186 if (new_index != 0) {
2187 // the original index is mapped so we have more work to do
2188 if (!StressLdcRewrite && new_index <= max_jubyte) {
2189 // The new value can still use ldc instead of ldc_w
2190 // unless we are trying to stress ldc -> ldc_w rewriting
2191 log_trace(redefine, class, constantpool)
2192 ("%s@" INTPTR_FORMAT " old=%d, new=%d", Bytecodes::name(c), p2i(bcp), cp_index, new_index);
2193 // We checked that new_index fits in a u1 so this cast is safe
2194 *(bcp + 1) = (u1)new_index;
2195 } else {
2196 log_trace(redefine, class, constantpool)
2197 ("%s->ldc_w@" INTPTR_FORMAT " old=%d, new=%d", Bytecodes::name(c), p2i(bcp), cp_index, new_index);
2198 // the new value needs ldc_w instead of ldc
2199 u_char inst_buffer[4]; // max instruction size is 4 bytes
2200 bcp = (address)inst_buffer;
2201 // construct new instruction sequence
2202 *bcp = Bytecodes::_ldc_w;
2203 bcp++;
2204 // Rewriter::rewrite_method() does not rewrite ldc -> ldc_w.
2205 // See comment below for difference between put_Java_u2()
2206 // and put_native_u2().
2207 Bytes::put_Java_u2(bcp, new_index);
2208
2209 Relocator rc(method, nullptr /* no RelocatorListener needed */);
2210 methodHandle m;
2211 {
2212 PauseNoSafepointVerifier pnsv(&nsv);
2213
2214 // ldc is 2 bytes and ldc_w is 3 bytes
2215 m = rc.insert_space_at(bci, 3, inst_buffer, CHECK);
2216 }
2217
2218 // return the new method so that the caller can update
2219 // the containing class
2220 *new_method_p = method = m;
2221 // switch our bytecode processing loop from the old method
2222 // to the new method
2223 code_base = method->code_base();
2224 code_length = method->code_size();
2225 bcp = code_base + bci;
2226 c = (Bytecodes::Code)(*bcp);
2227 bc_length = Bytecodes::length_for(c);
2228 assert(bc_length != 0, "sanity check");
2229 } // end we need ldc_w instead of ldc
2230 } // end if there is a mapped index
2231 } break;
2232
2233 // these bytecodes have a two-byte constant pool index
2234 case Bytecodes::_anewarray : // fall through
2235 case Bytecodes::_checkcast : // fall through
2236 case Bytecodes::_getfield : // fall through
2237 case Bytecodes::_getstatic : // fall through
2238 case Bytecodes::_instanceof : // fall through
2239 case Bytecodes::_invokedynamic : // fall through
2240 case Bytecodes::_invokeinterface: // fall through
2241 case Bytecodes::_invokespecial : // fall through
2242 case Bytecodes::_invokestatic : // fall through
2243 case Bytecodes::_invokevirtual : // fall through
2244 case Bytecodes::_ldc_w : // fall through
2245 case Bytecodes::_ldc2_w : // fall through
2246 case Bytecodes::_multianewarray : // fall through
2247 case Bytecodes::_new : // fall through
2248 case Bytecodes::_putfield : // fall through
2249 case Bytecodes::_putstatic :
2250 {
2251 address p = bcp + 1;
2252 int cp_index = Bytes::get_Java_u2(p);
2253 u2 new_index = find_new_index(cp_index);
2254 if (new_index != 0) {
2255 // the original index is mapped so update w/ new value
2256 log_trace(redefine, class, constantpool)
2257 ("%s@" INTPTR_FORMAT " old=%d, new=%d", Bytecodes::name(c),p2i(bcp), cp_index, new_index);
2258 // Rewriter::rewrite_method() uses put_native_u2() in this
2259 // situation because it is reusing the constant pool index
2260 // location for a native index into the ConstantPoolCache.
2261 // Since we are updating the constant pool index prior to
2262 // verification and ConstantPoolCache initialization, we
2263 // need to keep the new index in Java byte order.
2264 Bytes::put_Java_u2(p, new_index);
2265 }
2266 } break;
2267 default:
2268 break;
2269 }
2270 } // end for each bytecode
2271 } // end rewrite_cp_refs_in_method()
2272
2273
2274 // Rewrite constant pool references in the class_annotations field.
2275 bool VM_RedefineClasses::rewrite_cp_refs_in_class_annotations(InstanceKlass* scratch_class) {
2276
2277 AnnotationArray* class_annotations = scratch_class->class_annotations();
2278 if (class_annotations == nullptr || class_annotations->length() == 0) {
2279 // no class_annotations so nothing to do
2280 return true;
2281 }
2282
2283 log_debug(redefine, class, annotation)("class_annotations length=%d", class_annotations->length());
2284
2285 int byte_i = 0; // byte index into class_annotations
2286 return rewrite_cp_refs_in_annotations_typeArray(class_annotations, byte_i);
2287 }
2288
2289
2290 // Rewrite constant pool references in an annotations typeArray. This
2291 // "structure" is adapted from the RuntimeVisibleAnnotations_attribute
2292 // that is described in section 4.8.15 of the 2nd-edition of the VM spec:
2293 //
2294 // annotations_typeArray {
2295 // u2 num_annotations;
2296 // annotation annotations[num_annotations];
2297 // }
2298 //
2299 bool VM_RedefineClasses::rewrite_cp_refs_in_annotations_typeArray(
2300 AnnotationArray* annotations_typeArray, int &byte_i_ref) {
2301
2302 if ((byte_i_ref + 2) > annotations_typeArray->length()) {
2303 // not enough room for num_annotations field
2304 log_debug(redefine, class, annotation)("length() is too small for num_annotations field");
2305 return false;
2306 }
2307
2308 u2 num_annotations = Bytes::get_Java_u2((address)
2309 annotations_typeArray->adr_at(byte_i_ref));
2310 byte_i_ref += 2;
2311
2312 log_debug(redefine, class, annotation)("num_annotations=%d", num_annotations);
2313
2314 int calc_num_annotations = 0;
2315 for (; calc_num_annotations < num_annotations; calc_num_annotations++) {
2316 if (!rewrite_cp_refs_in_annotation_struct(annotations_typeArray, byte_i_ref)) {
2317 log_debug(redefine, class, annotation)("bad annotation_struct at %d", calc_num_annotations);
2318 // propagate failure back to caller
2319 return false;
2320 }
2321 }
2322 assert(num_annotations == calc_num_annotations, "sanity check");
2323
2324 return true;
2325 } // end rewrite_cp_refs_in_annotations_typeArray()
2326
2327
2328 // Rewrite constant pool references in the annotation struct portion of
2329 // an annotations_typeArray. This "structure" is from section 4.8.15 of
2330 // the 2nd-edition of the VM spec:
2331 //
2332 // struct annotation {
2333 // u2 type_index;
2334 // u2 num_element_value_pairs;
2335 // {
2336 // u2 element_name_index;
2337 // element_value value;
2338 // } element_value_pairs[num_element_value_pairs];
2339 // }
2340 //
2341 bool VM_RedefineClasses::rewrite_cp_refs_in_annotation_struct(
2342 AnnotationArray* annotations_typeArray, int &byte_i_ref) {
2343 if ((byte_i_ref + 2 + 2) > annotations_typeArray->length()) {
2344 // not enough room for smallest annotation_struct
2345 log_debug(redefine, class, annotation)("length() is too small for annotation_struct");
2346 return false;
2347 }
2348
2349 u2 type_index = rewrite_cp_ref_in_annotation_data(annotations_typeArray,
2350 byte_i_ref, "type_index");
2351
2352 u2 num_element_value_pairs = Bytes::get_Java_u2((address)
2353 annotations_typeArray->adr_at(byte_i_ref));
2354 byte_i_ref += 2;
2355
2356 log_debug(redefine, class, annotation)
2357 ("type_index=%d num_element_value_pairs=%d", type_index, num_element_value_pairs);
2358
2359 int calc_num_element_value_pairs = 0;
2360 for (; calc_num_element_value_pairs < num_element_value_pairs;
2361 calc_num_element_value_pairs++) {
2362 if ((byte_i_ref + 2) > annotations_typeArray->length()) {
2363 // not enough room for another element_name_index, let alone
2364 // the rest of another component
2365 log_debug(redefine, class, annotation)("length() is too small for element_name_index");
2366 return false;
2367 }
2368
2369 u2 element_name_index = rewrite_cp_ref_in_annotation_data(
2370 annotations_typeArray, byte_i_ref,
2371 "element_name_index");
2372
2373 log_debug(redefine, class, annotation)("element_name_index=%d", element_name_index);
2374
2375 if (!rewrite_cp_refs_in_element_value(annotations_typeArray, byte_i_ref)) {
2376 log_debug(redefine, class, annotation)("bad element_value at %d", calc_num_element_value_pairs);
2377 // propagate failure back to caller
2378 return false;
2379 }
2380 } // end for each component
2381 assert(num_element_value_pairs == calc_num_element_value_pairs,
2382 "sanity check");
2383
2384 return true;
2385 } // end rewrite_cp_refs_in_annotation_struct()
2386
2387
2388 // Rewrite a constant pool reference at the current position in
2389 // annotations_typeArray if needed. Returns the original constant
2390 // pool reference if a rewrite was not needed or the new constant
2391 // pool reference if a rewrite was needed.
2392 u2 VM_RedefineClasses::rewrite_cp_ref_in_annotation_data(
2393 AnnotationArray* annotations_typeArray, int &byte_i_ref,
2394 const char * trace_mesg) {
2395
2396 address cp_index_addr = (address)
2397 annotations_typeArray->adr_at(byte_i_ref);
2398 u2 old_cp_index = Bytes::get_Java_u2(cp_index_addr);
2399 u2 new_cp_index = find_new_index(old_cp_index);
2400 if (new_cp_index != 0) {
2401 log_debug(redefine, class, annotation)("mapped old %s=%d", trace_mesg, old_cp_index);
2402 Bytes::put_Java_u2(cp_index_addr, new_cp_index);
2403 old_cp_index = new_cp_index;
2404 }
2405 byte_i_ref += 2;
2406 return old_cp_index;
2407 }
2408
2409
2410 // Rewrite constant pool references in the element_value portion of an
2411 // annotations_typeArray. This "structure" is from section 4.8.15.1 of
2412 // the 2nd-edition of the VM spec:
2413 //
2414 // struct element_value {
2415 // u1 tag;
2416 // union {
2417 // u2 const_value_index;
2418 // {
2419 // u2 type_name_index;
2420 // u2 const_name_index;
2421 // } enum_const_value;
2422 // u2 class_info_index;
2423 // annotation annotation_value;
2424 // struct {
2425 // u2 num_values;
2426 // element_value values[num_values];
2427 // } array_value;
2428 // } value;
2429 // }
2430 //
2431 bool VM_RedefineClasses::rewrite_cp_refs_in_element_value(
2432 AnnotationArray* annotations_typeArray, int &byte_i_ref) {
2433
2434 if ((byte_i_ref + 1) > annotations_typeArray->length()) {
2435 // not enough room for a tag let alone the rest of an element_value
2436 log_debug(redefine, class, annotation)("length() is too small for a tag");
2437 return false;
2438 }
2439
2440 u1 tag = annotations_typeArray->at(byte_i_ref);
2441 byte_i_ref++;
2442 log_debug(redefine, class, annotation)("tag='%c'", tag);
2443
2444 switch (tag) {
2445 // These BaseType tag values are from Table 4.2 in VM spec:
2446 case JVM_SIGNATURE_BYTE:
2447 case JVM_SIGNATURE_CHAR:
2448 case JVM_SIGNATURE_DOUBLE:
2449 case JVM_SIGNATURE_FLOAT:
2450 case JVM_SIGNATURE_INT:
2451 case JVM_SIGNATURE_LONG:
2452 case JVM_SIGNATURE_SHORT:
2453 case JVM_SIGNATURE_BOOLEAN:
2454
2455 // The remaining tag values are from Table 4.8 in the 2nd-edition of
2456 // the VM spec:
2457 case 's':
2458 {
2459 // For the above tag values (including the BaseType values),
2460 // value.const_value_index is right union field.
2461
2462 if ((byte_i_ref + 2) > annotations_typeArray->length()) {
2463 // not enough room for a const_value_index
2464 log_debug(redefine, class, annotation)("length() is too small for a const_value_index");
2465 return false;
2466 }
2467
2468 u2 const_value_index = rewrite_cp_ref_in_annotation_data(
2469 annotations_typeArray, byte_i_ref,
2470 "const_value_index");
2471
2472 log_debug(redefine, class, annotation)("const_value_index=%d", const_value_index);
2473 } break;
2474
2475 case 'e':
2476 {
2477 // for the above tag value, value.enum_const_value is right union field
2478
2479 if ((byte_i_ref + 4) > annotations_typeArray->length()) {
2480 // not enough room for a enum_const_value
2481 log_debug(redefine, class, annotation)("length() is too small for a enum_const_value");
2482 return false;
2483 }
2484
2485 u2 type_name_index = rewrite_cp_ref_in_annotation_data(
2486 annotations_typeArray, byte_i_ref,
2487 "type_name_index");
2488
2489 u2 const_name_index = rewrite_cp_ref_in_annotation_data(
2490 annotations_typeArray, byte_i_ref,
2491 "const_name_index");
2492
2493 log_debug(redefine, class, annotation)
2494 ("type_name_index=%d const_name_index=%d", type_name_index, const_name_index);
2495 } break;
2496
2497 case 'c':
2498 {
2499 // for the above tag value, value.class_info_index is right union field
2500
2501 if ((byte_i_ref + 2) > annotations_typeArray->length()) {
2502 // not enough room for a class_info_index
2503 log_debug(redefine, class, annotation)("length() is too small for a class_info_index");
2504 return false;
2505 }
2506
2507 u2 class_info_index = rewrite_cp_ref_in_annotation_data(
2508 annotations_typeArray, byte_i_ref,
2509 "class_info_index");
2510
2511 log_debug(redefine, class, annotation)("class_info_index=%d", class_info_index);
2512 } break;
2513
2514 case '@':
2515 // For the above tag value, value.attr_value is the right union
2516 // field. This is a nested annotation.
2517 if (!rewrite_cp_refs_in_annotation_struct(annotations_typeArray, byte_i_ref)) {
2518 // propagate failure back to caller
2519 return false;
2520 }
2521 break;
2522
2523 case JVM_SIGNATURE_ARRAY:
2524 {
2525 if ((byte_i_ref + 2) > annotations_typeArray->length()) {
2526 // not enough room for a num_values field
2527 log_debug(redefine, class, annotation)("length() is too small for a num_values field");
2528 return false;
2529 }
2530
2531 // For the above tag value, value.array_value is the right union
2532 // field. This is an array of nested element_value.
2533 u2 num_values = Bytes::get_Java_u2((address)
2534 annotations_typeArray->adr_at(byte_i_ref));
2535 byte_i_ref += 2;
2536 log_debug(redefine, class, annotation)("num_values=%d", num_values);
2537
2538 int calc_num_values = 0;
2539 for (; calc_num_values < num_values; calc_num_values++) {
2540 if (!rewrite_cp_refs_in_element_value(annotations_typeArray, byte_i_ref)) {
2541 log_debug(redefine, class, annotation)("bad nested element_value at %d", calc_num_values);
2542 // propagate failure back to caller
2543 return false;
2544 }
2545 }
2546 assert(num_values == calc_num_values, "sanity check");
2547 } break;
2548
2549 default:
2550 log_debug(redefine, class, annotation)("bad tag=0x%x", tag);
2551 return false;
2552 } // end decode tag field
2553
2554 return true;
2555 } // end rewrite_cp_refs_in_element_value()
2556
2557
2558 // Rewrite constant pool references in a fields_annotations field.
2559 bool VM_RedefineClasses::rewrite_cp_refs_in_fields_annotations(
2560 InstanceKlass* scratch_class) {
2561
2562 Array<AnnotationArray*>* fields_annotations = scratch_class->fields_annotations();
2563
2564 if (fields_annotations == nullptr || fields_annotations->length() == 0) {
2565 // no fields_annotations so nothing to do
2566 return true;
2567 }
2568
2569 log_debug(redefine, class, annotation)("fields_annotations length=%d", fields_annotations->length());
2570
2571 for (int i = 0; i < fields_annotations->length(); i++) {
2572 AnnotationArray* field_annotations = fields_annotations->at(i);
2573 if (field_annotations == nullptr || field_annotations->length() == 0) {
2574 // this field does not have any annotations so skip it
2575 continue;
2576 }
2577
2578 int byte_i = 0; // byte index into field_annotations
2579 if (!rewrite_cp_refs_in_annotations_typeArray(field_annotations, byte_i)) {
2580 log_debug(redefine, class, annotation)("bad field_annotations at %d", i);
2581 // propagate failure back to caller
2582 return false;
2583 }
2584 }
2585
2586 return true;
2587 } // end rewrite_cp_refs_in_fields_annotations()
2588
2589
2590 // Rewrite constant pool references in a methods_annotations field.
2591 bool VM_RedefineClasses::rewrite_cp_refs_in_methods_annotations(
2592 InstanceKlass* scratch_class) {
2593
2594 for (int i = 0; i < scratch_class->methods()->length(); i++) {
2595 Method* m = scratch_class->methods()->at(i);
2596 AnnotationArray* method_annotations = m->constMethod()->method_annotations();
2597
2598 if (method_annotations == nullptr || method_annotations->length() == 0) {
2599 // this method does not have any annotations so skip it
2600 continue;
2601 }
2602
2603 int byte_i = 0; // byte index into method_annotations
2604 if (!rewrite_cp_refs_in_annotations_typeArray(method_annotations, byte_i)) {
2605 log_debug(redefine, class, annotation)("bad method_annotations at %d", i);
2606 // propagate failure back to caller
2607 return false;
2608 }
2609 }
2610
2611 return true;
2612 } // end rewrite_cp_refs_in_methods_annotations()
2613
2614
2615 // Rewrite constant pool references in a methods_parameter_annotations
2616 // field. This "structure" is adapted from the
2617 // RuntimeVisibleParameterAnnotations_attribute described in section
2618 // 4.8.17 of the 2nd-edition of the VM spec:
2619 //
2620 // methods_parameter_annotations_typeArray {
2621 // u1 num_parameters;
2622 // {
2623 // u2 num_annotations;
2624 // annotation annotations[num_annotations];
2625 // } parameter_annotations[num_parameters];
2626 // }
2627 //
2628 bool VM_RedefineClasses::rewrite_cp_refs_in_methods_parameter_annotations(
2629 InstanceKlass* scratch_class) {
2630
2631 for (int i = 0; i < scratch_class->methods()->length(); i++) {
2632 Method* m = scratch_class->methods()->at(i);
2633 AnnotationArray* method_parameter_annotations = m->constMethod()->parameter_annotations();
2634 if (method_parameter_annotations == nullptr
2635 || method_parameter_annotations->length() == 0) {
2636 // this method does not have any parameter annotations so skip it
2637 continue;
2638 }
2639
2640 if (method_parameter_annotations->length() < 1) {
2641 // not enough room for a num_parameters field
2642 log_debug(redefine, class, annotation)("length() is too small for a num_parameters field at %d", i);
2643 return false;
2644 }
2645
2646 int byte_i = 0; // byte index into method_parameter_annotations
2647
2648 u1 num_parameters = method_parameter_annotations->at(byte_i);
2649 byte_i++;
2650
2651 log_debug(redefine, class, annotation)("num_parameters=%d", num_parameters);
2652
2653 int calc_num_parameters = 0;
2654 for (; calc_num_parameters < num_parameters; calc_num_parameters++) {
2655 if (!rewrite_cp_refs_in_annotations_typeArray(method_parameter_annotations, byte_i)) {
2656 log_debug(redefine, class, annotation)("bad method_parameter_annotations at %d", calc_num_parameters);
2657 // propagate failure back to caller
2658 return false;
2659 }
2660 }
2661 assert(num_parameters == calc_num_parameters, "sanity check");
2662 }
2663
2664 return true;
2665 } // end rewrite_cp_refs_in_methods_parameter_annotations()
2666
2667
2668 // Rewrite constant pool references in a methods_default_annotations
2669 // field. This "structure" is adapted from the AnnotationDefault_attribute
2670 // that is described in section 4.8.19 of the 2nd-edition of the VM spec:
2671 //
2672 // methods_default_annotations_typeArray {
2673 // element_value default_value;
2674 // }
2675 //
2676 bool VM_RedefineClasses::rewrite_cp_refs_in_methods_default_annotations(
2677 InstanceKlass* scratch_class) {
2678
2679 for (int i = 0; i < scratch_class->methods()->length(); i++) {
2680 Method* m = scratch_class->methods()->at(i);
2681 AnnotationArray* method_default_annotations = m->constMethod()->default_annotations();
2682 if (method_default_annotations == nullptr
2683 || method_default_annotations->length() == 0) {
2684 // this method does not have any default annotations so skip it
2685 continue;
2686 }
2687
2688 int byte_i = 0; // byte index into method_default_annotations
2689
2690 if (!rewrite_cp_refs_in_element_value(
2691 method_default_annotations, byte_i)) {
2692 log_debug(redefine, class, annotation)("bad default element_value at %d", i);
2693 // propagate failure back to caller
2694 return false;
2695 }
2696 }
2697
2698 return true;
2699 } // end rewrite_cp_refs_in_methods_default_annotations()
2700
2701
2702 // Rewrite constant pool references in a class_type_annotations field.
2703 bool VM_RedefineClasses::rewrite_cp_refs_in_class_type_annotations(
2704 InstanceKlass* scratch_class) {
2705
2706 AnnotationArray* class_type_annotations = scratch_class->class_type_annotations();
2707 if (class_type_annotations == nullptr || class_type_annotations->length() == 0) {
2708 // no class_type_annotations so nothing to do
2709 return true;
2710 }
2711
2712 log_debug(redefine, class, annotation)("class_type_annotations length=%d", class_type_annotations->length());
2713
2714 int byte_i = 0; // byte index into class_type_annotations
2715 return rewrite_cp_refs_in_type_annotations_typeArray(class_type_annotations,
2716 byte_i, "ClassFile");
2717 } // end rewrite_cp_refs_in_class_type_annotations()
2718
2719
2720 // Rewrite constant pool references in a fields_type_annotations field.
2721 bool VM_RedefineClasses::rewrite_cp_refs_in_fields_type_annotations(InstanceKlass* scratch_class) {
2722
2723 Array<AnnotationArray*>* fields_type_annotations = scratch_class->fields_type_annotations();
2724 if (fields_type_annotations == nullptr || fields_type_annotations->length() == 0) {
2725 // no fields_type_annotations so nothing to do
2726 return true;
2727 }
2728
2729 log_debug(redefine, class, annotation)("fields_type_annotations length=%d", fields_type_annotations->length());
2730
2731 for (int i = 0; i < fields_type_annotations->length(); i++) {
2732 AnnotationArray* field_type_annotations = fields_type_annotations->at(i);
2733 if (field_type_annotations == nullptr || field_type_annotations->length() == 0) {
2734 // this field does not have any annotations so skip it
2735 continue;
2736 }
2737
2738 int byte_i = 0; // byte index into field_type_annotations
2739 if (!rewrite_cp_refs_in_type_annotations_typeArray(field_type_annotations,
2740 byte_i, "field_info")) {
2741 log_debug(redefine, class, annotation)("bad field_type_annotations at %d", i);
2742 // propagate failure back to caller
2743 return false;
2744 }
2745 }
2746
2747 return true;
2748 } // end rewrite_cp_refs_in_fields_type_annotations()
2749
2750
2751 // Rewrite constant pool references in a methods_type_annotations field.
2752 bool VM_RedefineClasses::rewrite_cp_refs_in_methods_type_annotations(
2753 InstanceKlass* scratch_class) {
2754
2755 for (int i = 0; i < scratch_class->methods()->length(); i++) {
2756 Method* m = scratch_class->methods()->at(i);
2757 AnnotationArray* method_type_annotations = m->constMethod()->type_annotations();
2758
2759 if (method_type_annotations == nullptr || method_type_annotations->length() == 0) {
2760 // this method does not have any annotations so skip it
2761 continue;
2762 }
2763
2764 log_debug(redefine, class, annotation)("methods type_annotations length=%d", method_type_annotations->length());
2765
2766 int byte_i = 0; // byte index into method_type_annotations
2767 if (!rewrite_cp_refs_in_type_annotations_typeArray(method_type_annotations,
2768 byte_i, "method_info")) {
2769 log_debug(redefine, class, annotation)("bad method_type_annotations at %d", i);
2770 // propagate failure back to caller
2771 return false;
2772 }
2773 }
2774
2775 return true;
2776 } // end rewrite_cp_refs_in_methods_type_annotations()
2777
2778
2779 // Rewrite constant pool references in a type_annotations
2780 // field. This "structure" is adapted from the
2781 // RuntimeVisibleTypeAnnotations_attribute described in
2782 // section 4.7.20 of the Java SE 8 Edition of the VM spec:
2783 //
2784 // type_annotations_typeArray {
2785 // u2 num_annotations;
2786 // type_annotation annotations[num_annotations];
2787 // }
2788 //
2789 bool VM_RedefineClasses::rewrite_cp_refs_in_type_annotations_typeArray(
2790 AnnotationArray* type_annotations_typeArray, int &byte_i_ref,
2791 const char * location_mesg) {
2792
2793 if ((byte_i_ref + 2) > type_annotations_typeArray->length()) {
2794 // not enough room for num_annotations field
2795 log_debug(redefine, class, annotation)("length() is too small for num_annotations field");
2796 return false;
2797 }
2798
2799 u2 num_annotations = Bytes::get_Java_u2((address)
2800 type_annotations_typeArray->adr_at(byte_i_ref));
2801 byte_i_ref += 2;
2802
2803 log_debug(redefine, class, annotation)("num_type_annotations=%d", num_annotations);
2804
2805 int calc_num_annotations = 0;
2806 for (; calc_num_annotations < num_annotations; calc_num_annotations++) {
2807 if (!rewrite_cp_refs_in_type_annotation_struct(type_annotations_typeArray,
2808 byte_i_ref, location_mesg)) {
2809 log_debug(redefine, class, annotation)("bad type_annotation_struct at %d", calc_num_annotations);
2810 // propagate failure back to caller
2811 return false;
2812 }
2813 }
2814 assert(num_annotations == calc_num_annotations, "sanity check");
2815
2816 if (byte_i_ref != type_annotations_typeArray->length()) {
2817 log_debug(redefine, class, annotation)
2818 ("read wrong amount of bytes at end of processing type_annotations_typeArray (%d of %d bytes were read)",
2819 byte_i_ref, type_annotations_typeArray->length());
2820 return false;
2821 }
2822
2823 return true;
2824 } // end rewrite_cp_refs_in_type_annotations_typeArray()
2825
2826
2827 // Rewrite constant pool references in a type_annotation
2828 // field. This "structure" is adapted from the
2829 // RuntimeVisibleTypeAnnotations_attribute described in
2830 // section 4.7.20 of the Java SE 8 Edition of the VM spec:
2831 //
2832 // type_annotation {
2833 // u1 target_type;
2834 // union {
2835 // type_parameter_target;
2836 // supertype_target;
2837 // type_parameter_bound_target;
2838 // empty_target;
2839 // method_formal_parameter_target;
2840 // throws_target;
2841 // localvar_target;
2842 // catch_target;
2843 // offset_target;
2844 // type_argument_target;
2845 // } target_info;
2846 // type_path target_path;
2847 // annotation anno;
2848 // }
2849 //
2850 bool VM_RedefineClasses::rewrite_cp_refs_in_type_annotation_struct(
2851 AnnotationArray* type_annotations_typeArray, int &byte_i_ref,
2852 const char * location_mesg) {
2853
2854 if (!skip_type_annotation_target(type_annotations_typeArray,
2855 byte_i_ref, location_mesg)) {
2856 return false;
2857 }
2858
2859 if (!skip_type_annotation_type_path(type_annotations_typeArray, byte_i_ref)) {
2860 return false;
2861 }
2862
2863 if (!rewrite_cp_refs_in_annotation_struct(type_annotations_typeArray, byte_i_ref)) {
2864 return false;
2865 }
2866
2867 return true;
2868 } // end rewrite_cp_refs_in_type_annotation_struct()
2869
2870
2871 // Read, verify and skip over the target_type and target_info part
2872 // so that rewriting can continue in the later parts of the struct.
2873 //
2874 // u1 target_type;
2875 // union {
2876 // type_parameter_target;
2877 // supertype_target;
2878 // type_parameter_bound_target;
2879 // empty_target;
2880 // method_formal_parameter_target;
2881 // throws_target;
2882 // localvar_target;
2883 // catch_target;
2884 // offset_target;
2885 // type_argument_target;
2886 // } target_info;
2887 //
2888 bool VM_RedefineClasses::skip_type_annotation_target(
2889 AnnotationArray* type_annotations_typeArray, int &byte_i_ref,
2890 const char * location_mesg) {
2891
2892 if ((byte_i_ref + 1) > type_annotations_typeArray->length()) {
2893 // not enough room for a target_type let alone the rest of a type_annotation
2894 log_debug(redefine, class, annotation)("length() is too small for a target_type");
2895 return false;
2896 }
2897
2898 u1 target_type = type_annotations_typeArray->at(byte_i_ref);
2899 byte_i_ref += 1;
2900 log_debug(redefine, class, annotation)("target_type=0x%.2x", target_type);
2901 log_debug(redefine, class, annotation)("location=%s", location_mesg);
2902
2903 // Skip over target_info
2904 switch (target_type) {
2905 case 0x00:
2906 // kind: type parameter declaration of generic class or interface
2907 // location: ClassFile
2908 case 0x01:
2909 // kind: type parameter declaration of generic method or constructor
2910 // location: method_info
2911
2912 {
2913 // struct:
2914 // type_parameter_target {
2915 // u1 type_parameter_index;
2916 // }
2917 //
2918 if ((byte_i_ref + 1) > type_annotations_typeArray->length()) {
2919 log_debug(redefine, class, annotation)("length() is too small for a type_parameter_target");
2920 return false;
2921 }
2922
2923 u1 type_parameter_index = type_annotations_typeArray->at(byte_i_ref);
2924 byte_i_ref += 1;
2925
2926 log_debug(redefine, class, annotation)("type_parameter_target: type_parameter_index=%d", type_parameter_index);
2927 } break;
2928
2929 case 0x10:
2930 // kind: type in extends clause of class or interface declaration
2931 // or in implements clause of interface declaration
2932 // location: ClassFile
2933
2934 {
2935 // struct:
2936 // supertype_target {
2937 // u2 supertype_index;
2938 // }
2939 //
2940 if ((byte_i_ref + 2) > type_annotations_typeArray->length()) {
2941 log_debug(redefine, class, annotation)("length() is too small for a supertype_target");
2942 return false;
2943 }
2944
2945 u2 supertype_index = Bytes::get_Java_u2((address)
2946 type_annotations_typeArray->adr_at(byte_i_ref));
2947 byte_i_ref += 2;
2948
2949 log_debug(redefine, class, annotation)("supertype_target: supertype_index=%d", supertype_index);
2950 } break;
2951
2952 case 0x11:
2953 // kind: type in bound of type parameter declaration of generic class or interface
2954 // location: ClassFile
2955 case 0x12:
2956 // kind: type in bound of type parameter declaration of generic method or constructor
2957 // location: method_info
2958
2959 {
2960 // struct:
2961 // type_parameter_bound_target {
2962 // u1 type_parameter_index;
2963 // u1 bound_index;
2964 // }
2965 //
2966 if ((byte_i_ref + 2) > type_annotations_typeArray->length()) {
2967 log_debug(redefine, class, annotation)("length() is too small for a type_parameter_bound_target");
2968 return false;
2969 }
2970
2971 u1 type_parameter_index = type_annotations_typeArray->at(byte_i_ref);
2972 byte_i_ref += 1;
2973 u1 bound_index = type_annotations_typeArray->at(byte_i_ref);
2974 byte_i_ref += 1;
2975
2976 log_debug(redefine, class, annotation)
2977 ("type_parameter_bound_target: type_parameter_index=%d, bound_index=%d", type_parameter_index, bound_index);
2978 } break;
2979
2980 case 0x13:
2981 // kind: type in field declaration
2982 // location: field_info
2983 case 0x14:
2984 // kind: return type of method, or type of newly constructed object
2985 // location: method_info
2986 case 0x15:
2987 // kind: receiver type of method or constructor
2988 // location: method_info
2989
2990 {
2991 // struct:
2992 // empty_target {
2993 // }
2994 //
2995 log_debug(redefine, class, annotation)("empty_target");
2996 } break;
2997
2998 case 0x16:
2999 // kind: type in formal parameter declaration of method, constructor, or lambda expression
3000 // location: method_info
3001
3002 {
3003 // struct:
3004 // formal_parameter_target {
3005 // u1 formal_parameter_index;
3006 // }
3007 //
3008 if ((byte_i_ref + 1) > type_annotations_typeArray->length()) {
3009 log_debug(redefine, class, annotation)("length() is too small for a formal_parameter_target");
3010 return false;
3011 }
3012
3013 u1 formal_parameter_index = type_annotations_typeArray->at(byte_i_ref);
3014 byte_i_ref += 1;
3015
3016 log_debug(redefine, class, annotation)
3017 ("formal_parameter_target: formal_parameter_index=%d", formal_parameter_index);
3018 } break;
3019
3020 case 0x17:
3021 // kind: type in throws clause of method or constructor
3022 // location: method_info
3023
3024 {
3025 // struct:
3026 // throws_target {
3027 // u2 throws_type_index
3028 // }
3029 //
3030 if ((byte_i_ref + 2) > type_annotations_typeArray->length()) {
3031 log_debug(redefine, class, annotation)("length() is too small for a throws_target");
3032 return false;
3033 }
3034
3035 u2 throws_type_index = Bytes::get_Java_u2((address)
3036 type_annotations_typeArray->adr_at(byte_i_ref));
3037 byte_i_ref += 2;
3038
3039 log_debug(redefine, class, annotation)("throws_target: throws_type_index=%d", throws_type_index);
3040 } break;
3041
3042 case 0x40:
3043 // kind: type in local variable declaration
3044 // location: Code
3045 case 0x41:
3046 // kind: type in resource variable declaration
3047 // location: Code
3048
3049 {
3050 // struct:
3051 // localvar_target {
3052 // u2 table_length;
3053 // struct {
3054 // u2 start_pc;
3055 // u2 length;
3056 // u2 index;
3057 // } table[table_length];
3058 // }
3059 //
3060 if ((byte_i_ref + 2) > type_annotations_typeArray->length()) {
3061 // not enough room for a table_length let alone the rest of a localvar_target
3062 log_debug(redefine, class, annotation)("length() is too small for a localvar_target table_length");
3063 return false;
3064 }
3065
3066 u2 table_length = Bytes::get_Java_u2((address)
3067 type_annotations_typeArray->adr_at(byte_i_ref));
3068 byte_i_ref += 2;
3069
3070 log_debug(redefine, class, annotation)("localvar_target: table_length=%d", table_length);
3071
3072 int table_struct_size = 2 + 2 + 2; // 3 u2 variables per table entry
3073 int table_size = table_length * table_struct_size;
3074
3075 if ((byte_i_ref + table_size) > type_annotations_typeArray->length()) {
3076 // not enough room for a table
3077 log_debug(redefine, class, annotation)("length() is too small for a table array of length %d", table_length);
3078 return false;
3079 }
3080
3081 // Skip over table
3082 byte_i_ref += table_size;
3083 } break;
3084
3085 case 0x42:
3086 // kind: type in exception parameter declaration
3087 // location: Code
3088
3089 {
3090 // struct:
3091 // catch_target {
3092 // u2 exception_table_index;
3093 // }
3094 //
3095 if ((byte_i_ref + 2) > type_annotations_typeArray->length()) {
3096 log_debug(redefine, class, annotation)("length() is too small for a catch_target");
3097 return false;
3098 }
3099
3100 u2 exception_table_index = Bytes::get_Java_u2((address)
3101 type_annotations_typeArray->adr_at(byte_i_ref));
3102 byte_i_ref += 2;
3103
3104 log_debug(redefine, class, annotation)("catch_target: exception_table_index=%d", exception_table_index);
3105 } break;
3106
3107 case 0x43:
3108 // kind: type in instanceof expression
3109 // location: Code
3110 case 0x44:
3111 // kind: type in new expression
3112 // location: Code
3113 case 0x45:
3114 // kind: type in method reference expression using ::new
3115 // location: Code
3116 case 0x46:
3117 // kind: type in method reference expression using ::Identifier
3118 // location: Code
3119
3120 {
3121 // struct:
3122 // offset_target {
3123 // u2 offset;
3124 // }
3125 //
3126 if ((byte_i_ref + 2) > type_annotations_typeArray->length()) {
3127 log_debug(redefine, class, annotation)("length() is too small for a offset_target");
3128 return false;
3129 }
3130
3131 u2 offset = Bytes::get_Java_u2((address)
3132 type_annotations_typeArray->adr_at(byte_i_ref));
3133 byte_i_ref += 2;
3134
3135 log_debug(redefine, class, annotation)("offset_target: offset=%d", offset);
3136 } break;
3137
3138 case 0x47:
3139 // kind: type in cast expression
3140 // location: Code
3141 case 0x48:
3142 // kind: type argument for generic constructor in new expression or
3143 // explicit constructor invocation statement
3144 // location: Code
3145 case 0x49:
3146 // kind: type argument for generic method in method invocation expression
3147 // location: Code
3148 case 0x4A:
3149 // kind: type argument for generic constructor in method reference expression using ::new
3150 // location: Code
3151 case 0x4B:
3152 // kind: type argument for generic method in method reference expression using ::Identifier
3153 // location: Code
3154
3155 {
3156 // struct:
3157 // type_argument_target {
3158 // u2 offset;
3159 // u1 type_argument_index;
3160 // }
3161 //
3162 if ((byte_i_ref + 3) > type_annotations_typeArray->length()) {
3163 log_debug(redefine, class, annotation)("length() is too small for a type_argument_target");
3164 return false;
3165 }
3166
3167 u2 offset = Bytes::get_Java_u2((address)
3168 type_annotations_typeArray->adr_at(byte_i_ref));
3169 byte_i_ref += 2;
3170 u1 type_argument_index = type_annotations_typeArray->at(byte_i_ref);
3171 byte_i_ref += 1;
3172
3173 log_debug(redefine, class, annotation)
3174 ("type_argument_target: offset=%d, type_argument_index=%d", offset, type_argument_index);
3175 } break;
3176
3177 default:
3178 log_debug(redefine, class, annotation)("unknown target_type");
3179 #ifdef ASSERT
3180 ShouldNotReachHere();
3181 #endif
3182 return false;
3183 }
3184
3185 return true;
3186 } // end skip_type_annotation_target()
3187
3188
3189 // Read, verify and skip over the type_path part so that rewriting
3190 // can continue in the later parts of the struct.
3191 //
3192 // type_path {
3193 // u1 path_length;
3194 // {
3195 // u1 type_path_kind;
3196 // u1 type_argument_index;
3197 // } path[path_length];
3198 // }
3199 //
3200 bool VM_RedefineClasses::skip_type_annotation_type_path(
3201 AnnotationArray* type_annotations_typeArray, int &byte_i_ref) {
3202
3203 if ((byte_i_ref + 1) > type_annotations_typeArray->length()) {
3204 // not enough room for a path_length let alone the rest of the type_path
3205 log_debug(redefine, class, annotation)("length() is too small for a type_path");
3206 return false;
3207 }
3208
3209 u1 path_length = type_annotations_typeArray->at(byte_i_ref);
3210 byte_i_ref += 1;
3211
3212 log_debug(redefine, class, annotation)("type_path: path_length=%d", path_length);
3213
3214 int calc_path_length = 0;
3215 for (; calc_path_length < path_length; calc_path_length++) {
3216 if ((byte_i_ref + 1 + 1) > type_annotations_typeArray->length()) {
3217 // not enough room for a path
3218 log_debug(redefine, class, annotation)
3219 ("length() is too small for path entry %d of %d", calc_path_length, path_length);
3220 return false;
3221 }
3222
3223 u1 type_path_kind = type_annotations_typeArray->at(byte_i_ref);
3224 byte_i_ref += 1;
3225 u1 type_argument_index = type_annotations_typeArray->at(byte_i_ref);
3226 byte_i_ref += 1;
3227
3228 log_debug(redefine, class, annotation)
3229 ("type_path: path[%d]: type_path_kind=%d, type_argument_index=%d",
3230 calc_path_length, type_path_kind, type_argument_index);
3231
3232 if (type_path_kind > 3 || (type_path_kind != 3 && type_argument_index != 0)) {
3233 // not enough room for a path
3234 log_debug(redefine, class, annotation)("inconsistent type_path values");
3235 return false;
3236 }
3237 }
3238 assert(path_length == calc_path_length, "sanity check");
3239
3240 return true;
3241 } // end skip_type_annotation_type_path()
3242
3243
3244 // Rewrite constant pool references in the method's stackmap table.
3245 // These "structures" are adapted from the StackMapTable_attribute that
3246 // is described in section 4.8.4 of the 6.0 version of the VM spec
3247 // (dated 2005.10.26):
3248 // file:///net/quincunx.sfbay/export/gbracha/ClassFile-Java6.pdf
3249 //
3250 // stack_map {
3251 // u2 number_of_entries;
3252 // stack_map_frame entries[number_of_entries];
3253 // }
3254 //
3255 void VM_RedefineClasses::rewrite_cp_refs_in_stack_map_table(
3256 const methodHandle& method) {
3257
3258 if (!method->has_stackmap_table()) {
3259 return;
3260 }
3261
3262 AnnotationArray* stackmap_data = method->stackmap_data();
3263 address stackmap_p = (address)stackmap_data->adr_at(0);
3264 address stackmap_end = stackmap_p + stackmap_data->length();
3265
3266 assert(stackmap_p + 2 <= stackmap_end, "no room for number_of_entries");
3267 u2 number_of_entries = Bytes::get_Java_u2(stackmap_p);
3268 stackmap_p += 2;
3269
3270 log_debug(redefine, class, stackmap)("number_of_entries=%u", number_of_entries);
3271
3272 // walk through each stack_map_frame
3273 u2 calc_number_of_entries = 0;
3274 for (; calc_number_of_entries < number_of_entries; calc_number_of_entries++) {
3275 // The stack_map_frame structure is a u1 frame_type followed by
3276 // 0 or more bytes of data:
3277 //
3278 // union stack_map_frame {
3279 // same_frame;
3280 // same_locals_1_stack_item_frame;
3281 // same_locals_1_stack_item_frame_extended;
3282 // chop_frame;
3283 // same_frame_extended;
3284 // append_frame;
3285 // full_frame;
3286 // }
3287
3288 assert(stackmap_p + 1 <= stackmap_end, "no room for frame_type");
3289 u1 frame_type = *stackmap_p;
3290 stackmap_p++;
3291
3292 // same_frame {
3293 // u1 frame_type = SAME; /* 0-63 */
3294 // }
3295 if (frame_type <= 63) {
3296 // nothing more to do for same_frame
3297 }
3298
3299 // same_locals_1_stack_item_frame {
3300 // u1 frame_type = SAME_LOCALS_1_STACK_ITEM; /* 64-127 */
3301 // verification_type_info stack[1];
3302 // }
3303 else if (frame_type >= 64 && frame_type <= 127) {
3304 rewrite_cp_refs_in_verification_type_info(stackmap_p, stackmap_end,
3305 calc_number_of_entries, frame_type);
3306 }
3307
3308 // reserved for future use
3309 else if (frame_type >= 128 && frame_type <= 246) {
3310 // nothing more to do for reserved frame_types
3311 }
3312
3313 // same_locals_1_stack_item_frame_extended {
3314 // u1 frame_type = SAME_LOCALS_1_STACK_ITEM_EXTENDED; /* 247 */
3315 // u2 offset_delta;
3316 // verification_type_info stack[1];
3317 // }
3318 else if (frame_type == 247) {
3319 stackmap_p += 2;
3320 rewrite_cp_refs_in_verification_type_info(stackmap_p, stackmap_end,
3321 calc_number_of_entries, frame_type);
3322 }
3323
3324 // chop_frame {
3325 // u1 frame_type = CHOP; /* 248-250 */
3326 // u2 offset_delta;
3327 // }
3328 else if (frame_type >= 248 && frame_type <= 250) {
3329 stackmap_p += 2;
3330 }
3331
3332 // same_frame_extended {
3333 // u1 frame_type = SAME_FRAME_EXTENDED; /* 251*/
3334 // u2 offset_delta;
3335 // }
3336 else if (frame_type == 251) {
3337 stackmap_p += 2;
3338 }
3339
3340 // append_frame {
3341 // u1 frame_type = APPEND; /* 252-254 */
3342 // u2 offset_delta;
3343 // verification_type_info locals[frame_type - 251];
3344 // }
3345 else if (frame_type >= 252 && frame_type <= 254) {
3346 assert(stackmap_p + 2 <= stackmap_end,
3347 "no room for offset_delta");
3348 stackmap_p += 2;
3349 u1 len = frame_type - 251;
3350 for (u1 i = 0; i < len; i++) {
3351 rewrite_cp_refs_in_verification_type_info(stackmap_p, stackmap_end,
3352 calc_number_of_entries, frame_type);
3353 }
3354 }
3355
3356 // full_frame {
3357 // u1 frame_type = FULL_FRAME; /* 255 */
3358 // u2 offset_delta;
3359 // u2 number_of_locals;
3360 // verification_type_info locals[number_of_locals];
3361 // u2 number_of_stack_items;
3362 // verification_type_info stack[number_of_stack_items];
3363 // }
3364 else if (frame_type == 255) {
3365 assert(stackmap_p + 2 + 2 <= stackmap_end,
3366 "no room for smallest full_frame");
3367 stackmap_p += 2;
3368
3369 u2 number_of_locals = Bytes::get_Java_u2(stackmap_p);
3370 stackmap_p += 2;
3371
3372 for (u2 locals_i = 0; locals_i < number_of_locals; locals_i++) {
3373 rewrite_cp_refs_in_verification_type_info(stackmap_p, stackmap_end,
3374 calc_number_of_entries, frame_type);
3375 }
3376
3377 // Use the largest size for the number_of_stack_items, but only get
3378 // the right number of bytes.
3379 u2 number_of_stack_items = Bytes::get_Java_u2(stackmap_p);
3380 stackmap_p += 2;
3381
3382 for (u2 stack_i = 0; stack_i < number_of_stack_items; stack_i++) {
3383 rewrite_cp_refs_in_verification_type_info(stackmap_p, stackmap_end,
3384 calc_number_of_entries, frame_type);
3385 }
3386 }
3387 } // end while there is a stack_map_frame
3388 assert(number_of_entries == calc_number_of_entries, "sanity check");
3389 } // end rewrite_cp_refs_in_stack_map_table()
3390
3391
3392 // Rewrite constant pool references in the verification type info
3393 // portion of the method's stackmap table. These "structures" are
3394 // adapted from the StackMapTable_attribute that is described in
3395 // section 4.8.4 of the 6.0 version of the VM spec (dated 2005.10.26):
3396 // file:///net/quincunx.sfbay/export/gbracha/ClassFile-Java6.pdf
3397 //
3398 // The verification_type_info structure is a u1 tag followed by 0 or
3399 // more bytes of data:
3400 //
3401 // union verification_type_info {
3402 // Top_variable_info;
3403 // Integer_variable_info;
3404 // Float_variable_info;
3405 // Long_variable_info;
3406 // Double_variable_info;
3407 // Null_variable_info;
3408 // UninitializedThis_variable_info;
3409 // Object_variable_info;
3410 // Uninitialized_variable_info;
3411 // }
3412 //
3413 void VM_RedefineClasses::rewrite_cp_refs_in_verification_type_info(
3414 address& stackmap_p_ref, address stackmap_end, u2 frame_i,
3415 u1 frame_type) {
3416
3417 assert(stackmap_p_ref + 1 <= stackmap_end, "no room for tag");
3418 u1 tag = *stackmap_p_ref;
3419 stackmap_p_ref++;
3420
3421 switch (tag) {
3422 // Top_variable_info {
3423 // u1 tag = ITEM_Top; /* 0 */
3424 // }
3425 // verificationType.hpp has zero as ITEM_Bogus instead of ITEM_Top
3426 case 0: // fall through
3427
3428 // Integer_variable_info {
3429 // u1 tag = ITEM_Integer; /* 1 */
3430 // }
3431 case ITEM_Integer: // fall through
3432
3433 // Float_variable_info {
3434 // u1 tag = ITEM_Float; /* 2 */
3435 // }
3436 case ITEM_Float: // fall through
3437
3438 // Double_variable_info {
3439 // u1 tag = ITEM_Double; /* 3 */
3440 // }
3441 case ITEM_Double: // fall through
3442
3443 // Long_variable_info {
3444 // u1 tag = ITEM_Long; /* 4 */
3445 // }
3446 case ITEM_Long: // fall through
3447
3448 // Null_variable_info {
3449 // u1 tag = ITEM_Null; /* 5 */
3450 // }
3451 case ITEM_Null: // fall through
3452
3453 // UninitializedThis_variable_info {
3454 // u1 tag = ITEM_UninitializedThis; /* 6 */
3455 // }
3456 case ITEM_UninitializedThis:
3457 // nothing more to do for the above tag types
3458 break;
3459
3460 // Object_variable_info {
3461 // u1 tag = ITEM_Object; /* 7 */
3462 // u2 cpool_index;
3463 // }
3464 case ITEM_Object:
3465 {
3466 assert(stackmap_p_ref + 2 <= stackmap_end, "no room for cpool_index");
3467 u2 cpool_index = Bytes::get_Java_u2(stackmap_p_ref);
3468 u2 new_cp_index = find_new_index(cpool_index);
3469 if (new_cp_index != 0) {
3470 log_debug(redefine, class, stackmap)("mapped old cpool_index=%d", cpool_index);
3471 Bytes::put_Java_u2(stackmap_p_ref, new_cp_index);
3472 cpool_index = new_cp_index;
3473 }
3474 stackmap_p_ref += 2;
3475
3476 log_debug(redefine, class, stackmap)
3477 ("frame_i=%u, frame_type=%u, cpool_index=%d", frame_i, frame_type, cpool_index);
3478 } break;
3479
3480 // Uninitialized_variable_info {
3481 // u1 tag = ITEM_Uninitialized; /* 8 */
3482 // u2 offset;
3483 // }
3484 case ITEM_Uninitialized:
3485 assert(stackmap_p_ref + 2 <= stackmap_end, "no room for offset");
3486 stackmap_p_ref += 2;
3487 break;
3488
3489 default:
3490 log_debug(redefine, class, stackmap)("frame_i=%u, frame_type=%u, bad tag=0x%x", frame_i, frame_type, tag);
3491 ShouldNotReachHere();
3492 break;
3493 } // end switch (tag)
3494 } // end rewrite_cp_refs_in_verification_type_info()
3495
3496
3497 // Change the constant pool associated with klass scratch_class to scratch_cp.
3498 // scratch_cp_length elements are copied from scratch_cp to a smaller constant pool
3499 // and the smaller constant pool is associated with scratch_class.
3500 void VM_RedefineClasses::set_new_constant_pool(
3501 ClassLoaderData* loader_data,
3502 InstanceKlass* scratch_class, constantPoolHandle scratch_cp,
3503 int scratch_cp_length, TRAPS) {
3504 assert(scratch_cp->length() >= scratch_cp_length, "sanity check");
3505
3506 // scratch_cp is a merged constant pool and has enough space for a
3507 // worst case merge situation. We want to associate the minimum
3508 // sized constant pool with the klass to save space.
3509 ConstantPool* cp = ConstantPool::allocate(loader_data, scratch_cp_length, CHECK);
3510 constantPoolHandle smaller_cp(THREAD, cp);
3511
3512 // preserve version() value in the smaller copy
3513 int version = scratch_cp->version();
3514 assert(version != 0, "sanity check");
3515 smaller_cp->set_version(version);
3516
3517 // attach klass to new constant pool
3518 // reference to the cp holder is needed for copy_operands()
3519 smaller_cp->set_pool_holder(scratch_class);
3520
3521 smaller_cp->copy_fields(scratch_cp());
3522
3523 scratch_cp->copy_cp_to(1, scratch_cp_length - 1, smaller_cp, 1, THREAD);
3524 if (HAS_PENDING_EXCEPTION) {
3525 // Exception is handled in the caller
3526 loader_data->add_to_deallocate_list(smaller_cp());
3527 return;
3528 }
3529 scratch_cp = smaller_cp;
3530
3531 // attach new constant pool to klass
3532 scratch_class->set_constants(scratch_cp());
3533 scratch_cp->initialize_unresolved_klasses(loader_data, CHECK);
3534
3535 int i; // for portability
3536
3537 // update each field in klass to use new constant pool indices as needed
3538 int java_fields;
3539 int injected_fields;
3540 bool update_required = false;
3541 GrowableArray<FieldInfo>* fields = FieldInfoStream::create_FieldInfoArray(scratch_class->fieldinfo_stream(), &java_fields, &injected_fields);
3542 for (int i = 0; i < java_fields; i++) {
3543 FieldInfo* fi = fields->adr_at(i);
3544 jshort cur_index = fi->name_index();
3545 jshort new_index = find_new_index(cur_index);
3546 if (new_index != 0) {
3547 log_trace(redefine, class, constantpool)("field-name_index change: %d to %d", cur_index, new_index);
3548 fi->set_name_index(new_index);
3549 update_required = true;
3550 }
3551 cur_index = fi->signature_index();
3552 new_index = find_new_index(cur_index);
3553 if (new_index != 0) {
3554 log_trace(redefine, class, constantpool)("field-signature_index change: %d to %d", cur_index, new_index);
3555 fi->set_signature_index(new_index);
3556 update_required = true;
3557 }
3558 cur_index = fi->initializer_index();
3559 new_index = find_new_index(cur_index);
3560 if (new_index != 0) {
3561 log_trace(redefine, class, constantpool)("field-initval_index change: %d to %d", cur_index, new_index);
3562 fi->set_initializer_index(new_index);
3563 update_required = true;
3564 }
3565 cur_index = fi->generic_signature_index();
3566 new_index = find_new_index(cur_index);
3567 if (new_index != 0) {
3568 log_trace(redefine, class, constantpool)("field-generic_signature change: %d to %d", cur_index, new_index);
3569 fi->set_generic_signature_index(new_index);
3570 update_required = true;
3571 }
3572 }
3573 if (update_required) {
3574 Array<u1>* old_stream = scratch_class->fieldinfo_stream();
3575 assert(fields->length() == (java_fields + injected_fields), "Must be");
3576 Array<u1>* new_fis = FieldInfoStream::create_FieldInfoStream(fields, java_fields, injected_fields, scratch_class->class_loader_data(), CHECK);
3577 scratch_class->set_fieldinfo_stream(new_fis);
3578 MetadataFactory::free_array<u1>(scratch_class->class_loader_data(), old_stream);
3579 }
3580
3581 // Update constant pool indices in the inner classes info to use
3582 // new constant indices as needed. The inner classes info is a
3583 // quadruple:
3584 // (inner_class_info, outer_class_info, inner_name, inner_access_flags)
3585 InnerClassesIterator iter(scratch_class);
3586 for (; !iter.done(); iter.next()) {
3587 int cur_index = iter.inner_class_info_index();
3588 if (cur_index == 0) {
3589 continue; // JVM spec. allows null inner class refs so skip it
3590 }
3591 u2 new_index = find_new_index(cur_index);
3592 if (new_index != 0) {
3593 log_trace(redefine, class, constantpool)("inner_class_info change: %d to %d", cur_index, new_index);
3594 iter.set_inner_class_info_index(new_index);
3595 }
3596 cur_index = iter.outer_class_info_index();
3597 new_index = find_new_index(cur_index);
3598 if (new_index != 0) {
3599 log_trace(redefine, class, constantpool)("outer_class_info change: %d to %d", cur_index, new_index);
3600 iter.set_outer_class_info_index(new_index);
3601 }
3602 cur_index = iter.inner_name_index();
3603 new_index = find_new_index(cur_index);
3604 if (new_index != 0) {
3605 log_trace(redefine, class, constantpool)("inner_name change: %d to %d", cur_index, new_index);
3606 iter.set_inner_name_index(new_index);
3607 }
3608 } // end for each inner class
3609
3610 // Attach each method in klass to the new constant pool and update
3611 // to use new constant pool indices as needed:
3612 Array<Method*>* methods = scratch_class->methods();
3613 for (i = methods->length() - 1; i >= 0; i--) {
3614 methodHandle method(THREAD, methods->at(i));
3615 method->set_constants(scratch_cp());
3616
3617 u2 new_index = find_new_index(method->name_index());
3618 if (new_index != 0) {
3619 log_trace(redefine, class, constantpool)
3620 ("method-name_index change: %d to %d", method->name_index(), new_index);
3621 method->set_name_index(new_index);
3622 }
3623 new_index = find_new_index(method->signature_index());
3624 if (new_index != 0) {
3625 log_trace(redefine, class, constantpool)
3626 ("method-signature_index change: %d to %d", method->signature_index(), new_index);
3627 method->set_signature_index(new_index);
3628 }
3629 new_index = find_new_index(method->generic_signature_index());
3630 if (new_index != 0) {
3631 log_trace(redefine, class, constantpool)
3632 ("method-generic_signature_index change: %d to %d", method->generic_signature_index(), new_index);
3633 method->constMethod()->set_generic_signature_index(new_index);
3634 }
3635
3636 // Update constant pool indices in the method's checked exception
3637 // table to use new constant indices as needed.
3638 int cext_length = method->checked_exceptions_length();
3639 if (cext_length > 0) {
3640 CheckedExceptionElement * cext_table =
3641 method->checked_exceptions_start();
3642 for (int j = 0; j < cext_length; j++) {
3643 int cur_index = cext_table[j].class_cp_index;
3644 int new_index = find_new_index(cur_index);
3645 if (new_index != 0) {
3646 log_trace(redefine, class, constantpool)("cext-class_cp_index change: %d to %d", cur_index, new_index);
3647 cext_table[j].class_cp_index = (u2)new_index;
3648 }
3649 } // end for each checked exception table entry
3650 } // end if there are checked exception table entries
3651
3652 // Update each catch type index in the method's exception table
3653 // to use new constant pool indices as needed. The exception table
3654 // holds quadruple entries of the form:
3655 // (beg_bci, end_bci, handler_bci, klass_index)
3656
3657 ExceptionTable ex_table(method());
3658 int ext_length = ex_table.length();
3659
3660 for (int j = 0; j < ext_length; j ++) {
3661 int cur_index = ex_table.catch_type_index(j);
3662 u2 new_index = find_new_index(cur_index);
3663 if (new_index != 0) {
3664 log_trace(redefine, class, constantpool)("ext-klass_index change: %d to %d", cur_index, new_index);
3665 ex_table.set_catch_type_index(j, new_index);
3666 }
3667 } // end for each exception table entry
3668
3669 // Update constant pool indices in the method's local variable
3670 // table to use new constant indices as needed. The local variable
3671 // table hold sextuple entries of the form:
3672 // (start_pc, length, name_index, descriptor_index, signature_index, slot)
3673 int lvt_length = method->localvariable_table_length();
3674 if (lvt_length > 0) {
3675 LocalVariableTableElement * lv_table =
3676 method->localvariable_table_start();
3677 for (int j = 0; j < lvt_length; j++) {
3678 int cur_index = lv_table[j].name_cp_index;
3679 int new_index = find_new_index(cur_index);
3680 if (new_index != 0) {
3681 log_trace(redefine, class, constantpool)("lvt-name_cp_index change: %d to %d", cur_index, new_index);
3682 lv_table[j].name_cp_index = (u2)new_index;
3683 }
3684 cur_index = lv_table[j].descriptor_cp_index;
3685 new_index = find_new_index(cur_index);
3686 if (new_index != 0) {
3687 log_trace(redefine, class, constantpool)("lvt-descriptor_cp_index change: %d to %d", cur_index, new_index);
3688 lv_table[j].descriptor_cp_index = (u2)new_index;
3689 }
3690 cur_index = lv_table[j].signature_cp_index;
3691 new_index = find_new_index(cur_index);
3692 if (new_index != 0) {
3693 log_trace(redefine, class, constantpool)("lvt-signature_cp_index change: %d to %d", cur_index, new_index);
3694 lv_table[j].signature_cp_index = (u2)new_index;
3695 }
3696 } // end for each local variable table entry
3697 } // end if there are local variable table entries
3698
3699 // Update constant pool indices in the method's method_parameters.
3700 int mp_length = method->method_parameters_length();
3701 if (mp_length > 0) {
3702 MethodParametersElement* elem = method->method_parameters_start();
3703 for (int j = 0; j < mp_length; j++) {
3704 const int cp_index = elem[j].name_cp_index;
3705 const int new_cp_index = find_new_index(cp_index);
3706 if (new_cp_index != 0) {
3707 elem[j].name_cp_index = (u2)new_cp_index;
3708 }
3709 }
3710 }
3711
3712 rewrite_cp_refs_in_stack_map_table(method);
3713 } // end for each method
3714 } // end set_new_constant_pool()
3715
3716
3717 // Unevolving classes may point to methods of the_class directly
3718 // from their constant pool caches, itables, and/or vtables. We
3719 // use the ClassLoaderDataGraph::classes_do() facility and this helper
3720 // to fix up these pointers. MethodData also points to old methods and
3721 // must be cleaned.
3722
3723 // Adjust cpools and vtables closure
3724 void VM_RedefineClasses::AdjustAndCleanMetadata::do_klass(Klass* k) {
3725
3726 // This is a very busy routine. We don't want too much tracing
3727 // printed out.
3728 bool trace_name_printed = false;
3729
3730 // If the class being redefined is java.lang.Object, we need to fix all
3731 // array class vtables also. The _has_redefined_Object flag is global.
3732 // Once the java.lang.Object has been redefined (by the current or one
3733 // of the previous VM_RedefineClasses operations) we have to always
3734 // adjust method entries for array classes.
3735 if (k->is_array_klass() && _has_redefined_Object) {
3736 k->vtable().adjust_method_entries(&trace_name_printed);
3737
3738 } else if (k->is_instance_klass()) {
3739 HandleMark hm(_thread);
3740 InstanceKlass *ik = InstanceKlass::cast(k);
3741
3742 // Clean MethodData of this class's methods so they don't refer to
3743 // old methods that are no longer running.
3744 Array<Method*>* methods = ik->methods();
3745 int num_methods = methods->length();
3746 for (int index = 0; index < num_methods; ++index) {
3747 if (methods->at(index)->method_data() != nullptr) {
3748 methods->at(index)->method_data()->clean_weak_method_links();
3749 }
3750 }
3751
3752 // Adjust all vtables, default methods and itables, to clean out old methods.
3753 ResourceMark rm(_thread);
3754 if (ik->vtable_length() > 0) {
3755 ik->vtable().adjust_method_entries(&trace_name_printed);
3756 ik->adjust_default_methods(&trace_name_printed);
3757 }
3758
3759 if (ik->itable_length() > 0) {
3760 ik->itable().adjust_method_entries(&trace_name_printed);
3761 }
3762
3763 // The constant pools in other classes (other_cp) can refer to
3764 // old methods. We have to update method information in
3765 // other_cp's cache. If other_cp has a previous version, then we
3766 // have to repeat the process for each previous version. The
3767 // constant pool cache holds the Method*s for non-virtual
3768 // methods and for virtual, final methods.
3769 //
3770 // Special case: if the current class is being redefined by the current
3771 // VM_RedefineClasses operation, then new_cp has already been attached
3772 // to the_class and old_cp has already been added as a previous version.
3773 // The new_cp doesn't have any cached references to old methods so it
3774 // doesn't need to be updated and we could optimize by skipping it.
3775 // However, the current class can be marked as being redefined by another
3776 // VM_RedefineClasses operation which has already executed its doit_prologue
3777 // and needs cpcache method entries adjusted. For simplicity, the cpcache
3778 // update is done unconditionally. It should result in doing nothing for
3779 // classes being redefined by the current VM_RedefineClasses operation.
3780 // Method entries in the previous version(s) are adjusted as well.
3781 ConstantPoolCache* cp_cache;
3782
3783 // this klass' constant pool cache may need adjustment
3784 ConstantPool* other_cp = ik->constants();
3785 cp_cache = other_cp->cache();
3786 if (cp_cache != nullptr) {
3787 cp_cache->adjust_method_entries(&trace_name_printed);
3788 }
3789
3790 // the previous versions' constant pool caches may need adjustment
3791 for (InstanceKlass* pv_node = ik->previous_versions();
3792 pv_node != nullptr;
3793 pv_node = pv_node->previous_versions()) {
3794 cp_cache = pv_node->constants()->cache();
3795 if (cp_cache != nullptr) {
3796 cp_cache->adjust_method_entries(&trace_name_printed);
3797 }
3798 }
3799 }
3800 }
3801
3802 void VM_RedefineClasses::update_jmethod_ids() {
3803 for (int j = 0; j < _matching_methods_length; ++j) {
3804 Method* old_method = _matching_old_methods[j];
3805 jmethodID jmid = old_method->find_jmethod_id_or_null();
3806 if (jmid != nullptr) {
3807 // There is a jmethodID, change it to point to the new method
3808 Method* new_method = _matching_new_methods[j];
3809 Method::change_method_associated_with_jmethod_id(jmid, new_method);
3810 assert(Method::resolve_jmethod_id(jmid) == _matching_new_methods[j],
3811 "should be replaced");
3812 }
3813 }
3814 }
3815
3816 int VM_RedefineClasses::check_methods_and_mark_as_obsolete() {
3817 int emcp_method_count = 0;
3818 int obsolete_count = 0;
3819 int old_index = 0;
3820 for (int j = 0; j < _matching_methods_length; ++j, ++old_index) {
3821 Method* old_method = _matching_old_methods[j];
3822 Method* new_method = _matching_new_methods[j];
3823 Method* old_array_method;
3824
3825 // Maintain an old_index into the _old_methods array by skipping
3826 // deleted methods
3827 while ((old_array_method = _old_methods->at(old_index)) != old_method) {
3828 ++old_index;
3829 }
3830
3831 if (MethodComparator::methods_EMCP(old_method, new_method)) {
3832 // The EMCP definition from JSR-163 requires the bytecodes to be
3833 // the same with the exception of constant pool indices which may
3834 // differ. However, the constants referred to by those indices
3835 // must be the same.
3836 //
3837 // We use methods_EMCP() for comparison since constant pool
3838 // merging can remove duplicate constant pool entries that were
3839 // present in the old method and removed from the rewritten new
3840 // method. A faster binary comparison function would consider the
3841 // old and new methods to be different when they are actually
3842 // EMCP.
3843 //
3844 // The old and new methods are EMCP and you would think that we
3845 // could get rid of one of them here and now and save some space.
3846 // However, the concept of EMCP only considers the bytecodes and
3847 // the constant pool entries in the comparison. Other things,
3848 // e.g., the line number table (LNT) or the local variable table
3849 // (LVT) don't count in the comparison. So the new (and EMCP)
3850 // method can have a new LNT that we need so we can't just
3851 // overwrite the new method with the old method.
3852 //
3853 // When this routine is called, we have already attached the new
3854 // methods to the_class so the old methods are effectively
3855 // overwritten. However, if an old method is still executing,
3856 // then the old method cannot be collected until sometime after
3857 // the old method call has returned. So the overwriting of old
3858 // methods by new methods will save us space except for those
3859 // (hopefully few) old methods that are still executing.
3860 //
3861 // A method refers to a ConstMethod* and this presents another
3862 // possible avenue to space savings. The ConstMethod* in the
3863 // new method contains possibly new attributes (LNT, LVT, etc).
3864 // At first glance, it seems possible to save space by replacing
3865 // the ConstMethod* in the old method with the ConstMethod*
3866 // from the new method. The old and new methods would share the
3867 // same ConstMethod* and we would save the space occupied by
3868 // the old ConstMethod*. However, the ConstMethod* contains
3869 // a back reference to the containing method. Sharing the
3870 // ConstMethod* between two methods could lead to confusion in
3871 // the code that uses the back reference. This would lead to
3872 // brittle code that could be broken in non-obvious ways now or
3873 // in the future.
3874 //
3875 // Another possibility is to copy the ConstMethod* from the new
3876 // method to the old method and then overwrite the new method with
3877 // the old method. Since the ConstMethod* contains the bytecodes
3878 // for the method embedded in the oop, this option would change
3879 // the bytecodes out from under any threads executing the old
3880 // method and make the thread's bcp invalid. Since EMCP requires
3881 // that the bytecodes be the same modulo constant pool indices, it
3882 // is straight forward to compute the correct new bcp in the new
3883 // ConstMethod* from the old bcp in the old ConstMethod*. The
3884 // time consuming part would be searching all the frames in all
3885 // of the threads to find all of the calls to the old method.
3886 //
3887 // It looks like we will have to live with the limited savings
3888 // that we get from effectively overwriting the old methods
3889 // when the new methods are attached to the_class.
3890
3891 // Count number of methods that are EMCP. The method will be marked
3892 // old but not obsolete if it is EMCP.
3893 emcp_method_count++;
3894
3895 // An EMCP method is _not_ obsolete. An obsolete method has a
3896 // different jmethodID than the current method. An EMCP method
3897 // has the same jmethodID as the current method. Having the
3898 // same jmethodID for all EMCP versions of a method allows for
3899 // a consistent view of the EMCP methods regardless of which
3900 // EMCP method you happen to have in hand. For example, a
3901 // breakpoint set in one EMCP method will work for all EMCP
3902 // versions of the method including the current one.
3903 } else {
3904 // mark obsolete methods as such
3905 old_method->set_is_obsolete();
3906 obsolete_count++;
3907
3908 // obsolete methods need a unique idnum so they become new entries in
3909 // the jmethodID cache in InstanceKlass
3910 assert(old_method->method_idnum() == new_method->method_idnum(), "must match");
3911 u2 num = InstanceKlass::cast(_the_class)->next_method_idnum();
3912 if (num != ConstMethod::UNSET_IDNUM) {
3913 old_method->set_method_idnum(num);
3914 }
3915
3916 // With tracing we try not to "yack" too much. The position of
3917 // this trace assumes there are fewer obsolete methods than
3918 // EMCP methods.
3919 if (log_is_enabled(Trace, redefine, class, obsolete, mark)) {
3920 ResourceMark rm;
3921 log_trace(redefine, class, obsolete, mark)
3922 ("mark %s(%s) as obsolete", old_method->name()->as_C_string(), old_method->signature()->as_C_string());
3923 }
3924 }
3925 old_method->set_is_old();
3926 }
3927 for (int i = 0; i < _deleted_methods_length; ++i) {
3928 Method* old_method = _deleted_methods[i];
3929
3930 assert(!old_method->has_vtable_index(),
3931 "cannot delete methods with vtable entries");;
3932
3933 // Mark all deleted methods as old, obsolete and deleted
3934 old_method->set_is_deleted();
3935 old_method->set_is_old();
3936 old_method->set_is_obsolete();
3937 ++obsolete_count;
3938 // With tracing we try not to "yack" too much. The position of
3939 // this trace assumes there are fewer obsolete methods than
3940 // EMCP methods.
3941 if (log_is_enabled(Trace, redefine, class, obsolete, mark)) {
3942 ResourceMark rm;
3943 log_trace(redefine, class, obsolete, mark)
3944 ("mark deleted %s(%s) as obsolete", old_method->name()->as_C_string(), old_method->signature()->as_C_string());
3945 }
3946 }
3947 assert((emcp_method_count + obsolete_count) == _old_methods->length(),
3948 "sanity check");
3949 log_trace(redefine, class, obsolete, mark)("EMCP_cnt=%d, obsolete_cnt=%d", emcp_method_count, obsolete_count);
3950 return emcp_method_count;
3951 }
3952
3953 // This internal class transfers the native function registration from old methods
3954 // to new methods. It is designed to handle both the simple case of unchanged
3955 // native methods and the complex cases of native method prefixes being added and/or
3956 // removed.
3957 // It expects only to be used during the VM_RedefineClasses op (a safepoint).
3958 //
3959 // This class is used after the new methods have been installed in "the_class".
3960 //
3961 // So, for example, the following must be handled. Where 'm' is a method and
3962 // a number followed by an underscore is a prefix.
3963 //
3964 // Old Name New Name
3965 // Simple transfer to new method m -> m
3966 // Add prefix m -> 1_m
3967 // Remove prefix 1_m -> m
3968 // Simultaneous add of prefixes m -> 3_2_1_m
3969 // Simultaneous removal of prefixes 3_2_1_m -> m
3970 // Simultaneous add and remove 1_m -> 2_m
3971 // Same, caused by prefix removal only 3_2_1_m -> 3_2_m
3972 //
3973 class TransferNativeFunctionRegistration {
3974 private:
3975 InstanceKlass* the_class;
3976 int prefix_count;
3977 char** prefixes;
3978
3979 // Recursively search the binary tree of possibly prefixed method names.
3980 // Iteration could be used if all agents were well behaved. Full tree walk is
3981 // more resilent to agents not cleaning up intermediate methods.
3982 // Branch at each depth in the binary tree is:
3983 // (1) without the prefix.
3984 // (2) with the prefix.
3985 // where 'prefix' is the prefix at that 'depth' (first prefix, second prefix,...)
3986 Method* search_prefix_name_space(int depth, char* name_str, size_t name_len,
3987 Symbol* signature) {
3988 TempNewSymbol name_symbol = SymbolTable::probe(name_str, (int)name_len);
3989 if (name_symbol != nullptr) {
3990 Method* method = the_class->lookup_method(name_symbol, signature);
3991 if (method != nullptr) {
3992 // Even if prefixed, intermediate methods must exist.
3993 if (method->is_native()) {
3994 // Wahoo, we found a (possibly prefixed) version of the method, return it.
3995 return method;
3996 }
3997 if (depth < prefix_count) {
3998 // Try applying further prefixes (other than this one).
3999 method = search_prefix_name_space(depth+1, name_str, name_len, signature);
4000 if (method != nullptr) {
4001 return method; // found
4002 }
4003
4004 // Try adding this prefix to the method name and see if it matches
4005 // another method name.
4006 char* prefix = prefixes[depth];
4007 size_t prefix_len = strlen(prefix);
4008 size_t trial_len = name_len + prefix_len;
4009 char* trial_name_str = NEW_RESOURCE_ARRAY(char, trial_len + 1);
4010 strcpy(trial_name_str, prefix);
4011 strcat(trial_name_str, name_str);
4012 method = search_prefix_name_space(depth+1, trial_name_str, trial_len,
4013 signature);
4014 if (method != nullptr) {
4015 // If found along this branch, it was prefixed, mark as such
4016 method->set_is_prefixed_native();
4017 return method; // found
4018 }
4019 }
4020 }
4021 }
4022 return nullptr; // This whole branch bore nothing
4023 }
4024
4025 // Return the method name with old prefixes stripped away.
4026 char* method_name_without_prefixes(Method* method) {
4027 Symbol* name = method->name();
4028 char* name_str = name->as_utf8();
4029
4030 // Old prefixing may be defunct, strip prefixes, if any.
4031 for (int i = prefix_count-1; i >= 0; i--) {
4032 char* prefix = prefixes[i];
4033 size_t prefix_len = strlen(prefix);
4034 if (strncmp(prefix, name_str, prefix_len) == 0) {
4035 name_str += prefix_len;
4036 }
4037 }
4038 return name_str;
4039 }
4040
4041 // Strip any prefixes off the old native method, then try to find a
4042 // (possibly prefixed) new native that matches it.
4043 Method* strip_and_search_for_new_native(Method* method) {
4044 ResourceMark rm;
4045 char* name_str = method_name_without_prefixes(method);
4046 return search_prefix_name_space(0, name_str, strlen(name_str),
4047 method->signature());
4048 }
4049
4050 public:
4051
4052 // Construct a native method transfer processor for this class.
4053 TransferNativeFunctionRegistration(InstanceKlass* _the_class) {
4054 assert(SafepointSynchronize::is_at_safepoint(), "sanity check");
4055
4056 the_class = _the_class;
4057 prefixes = JvmtiExport::get_all_native_method_prefixes(&prefix_count);
4058 }
4059
4060 // Attempt to transfer any of the old or deleted methods that are native
4061 void transfer_registrations(Method** old_methods, int methods_length) {
4062 for (int j = 0; j < methods_length; j++) {
4063 Method* old_method = old_methods[j];
4064
4065 if (old_method->is_native() && old_method->has_native_function()) {
4066 Method* new_method = strip_and_search_for_new_native(old_method);
4067 if (new_method != nullptr) {
4068 // Actually set the native function in the new method.
4069 // Redefine does not send events (except CFLH), certainly not this
4070 // behind the scenes re-registration.
4071 new_method->set_native_function(old_method->native_function(),
4072 !Method::native_bind_event_is_interesting);
4073 }
4074 }
4075 }
4076 }
4077 };
4078
4079 // Don't lose the association between a native method and its JNI function.
4080 void VM_RedefineClasses::transfer_old_native_function_registrations(InstanceKlass* the_class) {
4081 TransferNativeFunctionRegistration transfer(the_class);
4082 transfer.transfer_registrations(_deleted_methods, _deleted_methods_length);
4083 transfer.transfer_registrations(_matching_old_methods, _matching_methods_length);
4084 }
4085
4086 // Deoptimize all compiled code that depends on the classes redefined.
4087 //
4088 // If the can_redefine_classes capability is obtained in the onload
4089 // phase or 'AlwaysRecordEvolDependencies' is true, then the compiler has
4090 // recorded all dependencies from startup. In that case we need only
4091 // deoptimize and throw away all compiled code that depends on the class.
4092 //
4093 // If can_redefine_classes is obtained sometime after the onload phase
4094 // (and 'AlwaysRecordEvolDependencies' is false) then the dependency
4095 // information may be incomplete. In that case the first call to
4096 // RedefineClasses causes all compiled code to be thrown away. As
4097 // can_redefine_classes has been obtained then all future compilations will
4098 // record dependencies so second and subsequent calls to RedefineClasses
4099 // need only throw away code that depends on the class.
4100 //
4101
4102 void VM_RedefineClasses::flush_dependent_code() {
4103 assert(SafepointSynchronize::is_at_safepoint(), "sanity check");
4104 assert(JvmtiExport::all_dependencies_are_recorded() || !AlwaysRecordEvolDependencies, "sanity check");
4105
4106 DeoptimizationScope deopt_scope;
4107
4108 // This is the first redefinition, mark all the nmethods for deoptimization
4109 if (!JvmtiExport::all_dependencies_are_recorded()) {
4110 CodeCache::mark_all_nmethods_for_evol_deoptimization(&deopt_scope);
4111 log_debug(redefine, class, nmethod)("Marked all nmethods for deopt");
4112 } else {
4113 CodeCache::mark_dependents_for_evol_deoptimization(&deopt_scope);
4114 log_debug(redefine, class, nmethod)("Marked dependent nmethods for deopt");
4115 }
4116
4117 deopt_scope.deoptimize_marked();
4118
4119 // From now on we know that the dependency information is complete
4120 JvmtiExport::set_all_dependencies_are_recorded(true);
4121 }
4122
4123 void VM_RedefineClasses::compute_added_deleted_matching_methods() {
4124 Method* old_method;
4125 Method* new_method;
4126
4127 _matching_old_methods = NEW_RESOURCE_ARRAY(Method*, _old_methods->length());
4128 _matching_new_methods = NEW_RESOURCE_ARRAY(Method*, _old_methods->length());
4129 _added_methods = NEW_RESOURCE_ARRAY(Method*, _new_methods->length());
4130 _deleted_methods = NEW_RESOURCE_ARRAY(Method*, _old_methods->length());
4131
4132 _matching_methods_length = 0;
4133 _deleted_methods_length = 0;
4134 _added_methods_length = 0;
4135
4136 int nj = 0;
4137 int oj = 0;
4138 while (true) {
4139 if (oj >= _old_methods->length()) {
4140 if (nj >= _new_methods->length()) {
4141 break; // we've looked at everything, done
4142 }
4143 // New method at the end
4144 new_method = _new_methods->at(nj);
4145 _added_methods[_added_methods_length++] = new_method;
4146 ++nj;
4147 } else if (nj >= _new_methods->length()) {
4148 // Old method, at the end, is deleted
4149 old_method = _old_methods->at(oj);
4150 _deleted_methods[_deleted_methods_length++] = old_method;
4151 ++oj;
4152 } else {
4153 old_method = _old_methods->at(oj);
4154 new_method = _new_methods->at(nj);
4155 if (old_method->name() == new_method->name()) {
4156 if (old_method->signature() == new_method->signature()) {
4157 _matching_old_methods[_matching_methods_length ] = old_method;
4158 _matching_new_methods[_matching_methods_length++] = new_method;
4159 ++nj;
4160 ++oj;
4161 } else {
4162 // added overloaded have already been moved to the end,
4163 // so this is a deleted overloaded method
4164 _deleted_methods[_deleted_methods_length++] = old_method;
4165 ++oj;
4166 }
4167 } else { // names don't match
4168 if (old_method->name()->fast_compare(new_method->name()) > 0) {
4169 // new method
4170 _added_methods[_added_methods_length++] = new_method;
4171 ++nj;
4172 } else {
4173 // deleted method
4174 _deleted_methods[_deleted_methods_length++] = old_method;
4175 ++oj;
4176 }
4177 }
4178 }
4179 }
4180 assert(_matching_methods_length + _deleted_methods_length == _old_methods->length(), "sanity");
4181 assert(_matching_methods_length + _added_methods_length == _new_methods->length(), "sanity");
4182 }
4183
4184
4185 void VM_RedefineClasses::swap_annotations(InstanceKlass* the_class,
4186 InstanceKlass* scratch_class) {
4187 // Swap annotation fields values
4188 Annotations* old_annotations = the_class->annotations();
4189 the_class->set_annotations(scratch_class->annotations());
4190 scratch_class->set_annotations(old_annotations);
4191 }
4192
4193
4194 // Install the redefinition of a class:
4195 // - house keeping (flushing breakpoints and caches, deoptimizing
4196 // dependent compiled code)
4197 // - replacing parts in the_class with parts from scratch_class
4198 // - adding a weak reference to track the obsolete but interesting
4199 // parts of the_class
4200 // - adjusting constant pool caches and vtables in other classes
4201 // that refer to methods in the_class. These adjustments use the
4202 // ClassLoaderDataGraph::classes_do() facility which only allows
4203 // a helper method to be specified. The interesting parameters
4204 // that we would like to pass to the helper method are saved in
4205 // static global fields in the VM operation.
4206 void VM_RedefineClasses::redefine_single_class(Thread* current, jclass the_jclass,
4207 InstanceKlass* scratch_class) {
4208
4209 HandleMark hm(current); // make sure handles from this call are freed
4210
4211 if (log_is_enabled(Info, redefine, class, timer)) {
4212 _timer_rsc_phase1.start();
4213 }
4214
4215 InstanceKlass* the_class = get_ik(the_jclass);
4216
4217 // Set a flag to control and optimize adjusting method entries
4218 _has_redefined_Object |= the_class == vmClasses::Object_klass();
4219
4220 // Remove all breakpoints in methods of this class
4221 JvmtiBreakpoints& jvmti_breakpoints = JvmtiCurrentBreakpoints::get_jvmti_breakpoints();
4222 jvmti_breakpoints.clearall_in_class_at_safepoint(the_class);
4223
4224 _old_methods = the_class->methods();
4225 _new_methods = scratch_class->methods();
4226 _the_class = the_class;
4227 compute_added_deleted_matching_methods();
4228 update_jmethod_ids();
4229
4230 _any_class_has_resolved_methods = the_class->has_resolved_methods() || _any_class_has_resolved_methods;
4231
4232 // Attach new constant pool to the original klass. The original
4233 // klass still refers to the old constant pool (for now).
4234 scratch_class->constants()->set_pool_holder(the_class);
4235
4236 #if 0
4237 // In theory, with constant pool merging in place we should be able
4238 // to save space by using the new, merged constant pool in place of
4239 // the old constant pool(s). By "pool(s)" I mean the constant pool in
4240 // the klass version we are replacing now and any constant pool(s) in
4241 // previous versions of klass. Nice theory, doesn't work in practice.
4242 // When this code is enabled, even simple programs throw NullPointer
4243 // exceptions. I'm guessing that this is caused by some constant pool
4244 // cache difference between the new, merged constant pool and the
4245 // constant pool that was just being used by the klass. I'm keeping
4246 // this code around to archive the idea, but the code has to remain
4247 // disabled for now.
4248
4249 // Attach each old method to the new constant pool. This can be
4250 // done here since we are past the bytecode verification and
4251 // constant pool optimization phases.
4252 for (int i = _old_methods->length() - 1; i >= 0; i--) {
4253 Method* method = _old_methods->at(i);
4254 method->set_constants(scratch_class->constants());
4255 }
4256
4257 // NOTE: this doesn't work because you can redefine the same class in two
4258 // threads, each getting their own constant pool data appended to the
4259 // original constant pool. In order for the new methods to work when they
4260 // become old methods, they need to keep their updated copy of the constant pool.
4261
4262 {
4263 // walk all previous versions of the klass
4264 InstanceKlass *ik = the_class;
4265 PreviousVersionWalker pvw(ik);
4266 do {
4267 ik = pvw.next_previous_version();
4268 if (ik != nullptr) {
4269
4270 // attach previous version of klass to the new constant pool
4271 ik->set_constants(scratch_class->constants());
4272
4273 // Attach each method in the previous version of klass to the
4274 // new constant pool
4275 Array<Method*>* prev_methods = ik->methods();
4276 for (int i = prev_methods->length() - 1; i >= 0; i--) {
4277 Method* method = prev_methods->at(i);
4278 method->set_constants(scratch_class->constants());
4279 }
4280 }
4281 } while (ik != nullptr);
4282 }
4283 #endif
4284
4285 // Replace methods and constantpool
4286 the_class->set_methods(_new_methods);
4287 scratch_class->set_methods(_old_methods); // To prevent potential GCing of the old methods,
4288 // and to be able to undo operation easily.
4289
4290 Array<int>* old_ordering = the_class->method_ordering();
4291 the_class->set_method_ordering(scratch_class->method_ordering());
4292 scratch_class->set_method_ordering(old_ordering);
4293
4294 ConstantPool* old_constants = the_class->constants();
4295 the_class->set_constants(scratch_class->constants());
4296 scratch_class->set_constants(old_constants); // See the previous comment.
4297 #if 0
4298 // We are swapping the guts of "the new class" with the guts of "the
4299 // class". Since the old constant pool has just been attached to "the
4300 // new class", it seems logical to set the pool holder in the old
4301 // constant pool also. However, doing this will change the observable
4302 // class hierarchy for any old methods that are still executing. A
4303 // method can query the identity of its "holder" and this query uses
4304 // the method's constant pool link to find the holder. The change in
4305 // holding class from "the class" to "the new class" can confuse
4306 // things.
4307 //
4308 // Setting the old constant pool's holder will also cause
4309 // verification done during vtable initialization below to fail.
4310 // During vtable initialization, the vtable's class is verified to be
4311 // a subtype of the method's holder. The vtable's class is "the
4312 // class" and the method's holder is gotten from the constant pool
4313 // link in the method itself. For "the class"'s directly implemented
4314 // methods, the method holder is "the class" itself (as gotten from
4315 // the new constant pool). The check works fine in this case. The
4316 // check also works fine for methods inherited from super classes.
4317 //
4318 // Miranda methods are a little more complicated. A miranda method is
4319 // provided by an interface when the class implementing the interface
4320 // does not provide its own method. These interfaces are implemented
4321 // internally as an InstanceKlass. These special instanceKlasses
4322 // share the constant pool of the class that "implements" the
4323 // interface. By sharing the constant pool, the method holder of a
4324 // miranda method is the class that "implements" the interface. In a
4325 // non-redefine situation, the subtype check works fine. However, if
4326 // the old constant pool's pool holder is modified, then the check
4327 // fails because there is no class hierarchy relationship between the
4328 // vtable's class and "the new class".
4329
4330 old_constants->set_pool_holder(scratch_class());
4331 #endif
4332
4333 // track number of methods that are EMCP for add_previous_version() call below
4334 int emcp_method_count = check_methods_and_mark_as_obsolete();
4335 transfer_old_native_function_registrations(the_class);
4336
4337 if (scratch_class->get_cached_class_file() != the_class->get_cached_class_file()) {
4338 // 1. the_class doesn't have a cache yet, scratch_class does have a cache.
4339 // 2. The same class can be present twice in the scratch classes list or there
4340 // are multiple concurrent RetransformClasses calls on different threads.
4341 // the_class and scratch_class have the same cached bytes, but different buffers.
4342 // In such cases we need to deallocate one of the buffers.
4343 // 3. RedefineClasses and the_class has cached bytes from a previous transformation.
4344 // In the case we need to use class bytes from scratch_class.
4345 if (the_class->get_cached_class_file() != nullptr) {
4346 os::free(the_class->get_cached_class_file());
4347 }
4348 the_class->set_cached_class_file(scratch_class->get_cached_class_file());
4349 }
4350
4351 // null out in scratch class to not delete twice. The class to be redefined
4352 // always owns these bytes.
4353 scratch_class->set_cached_class_file(nullptr);
4354
4355 // Replace inner_classes
4356 Array<u2>* old_inner_classes = the_class->inner_classes();
4357 the_class->set_inner_classes(scratch_class->inner_classes());
4358 scratch_class->set_inner_classes(old_inner_classes);
4359
4360 // Initialize the vtable and interface table after
4361 // methods have been rewritten
4362 // no exception should happen here since we explicitly
4363 // do not check loader constraints.
4364 // compare_and_normalize_class_versions has already checked:
4365 // - classloaders unchanged, signatures unchanged
4366 // - all instanceKlasses for redefined classes reused & contents updated
4367 the_class->vtable().initialize_vtable();
4368 the_class->itable().initialize_itable();
4369
4370 // Update jmethodID cache if present.
4371 the_class->update_methods_jmethod_cache();
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 }