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/aotMetaspace.hpp"
26 #include "cds/cdsConfig.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/klassFactory.hpp"
32 #include "classfile/metadataOnStackMark.hpp"
33 #include "classfile/stackMapTable.hpp"
34 #include "classfile/symbolTable.hpp"
35 #include "classfile/verifier.hpp"
36 #include "classfile/vmClasses.hpp"
37 #include "classfile/vmSymbols.hpp"
38 #include "code/codeCache.hpp"
39 #include "compiler/compileBroker.hpp"
40 #include "interpreter/oopMapCache.hpp"
41 #include "interpreter/rewriter.hpp"
42 #include "jfr/jfrEvents.hpp"
43 #include "logging/logStream.hpp"
44 #include "memory/metadataFactory.hpp"
45 #include "memory/resourceArea.hpp"
46 #include "memory/universe.hpp"
47 #include "oops/annotations.hpp"
48 #include "oops/bsmAttribute.inline.hpp"
49 #include "oops/constantPool.inline.hpp"
50 #include "oops/fieldStreams.inline.hpp"
51 #include "oops/klass.inline.hpp"
52 #include "oops/klassVtable.hpp"
53 #include "oops/method.hpp"
54 #include "oops/oop.inline.hpp"
55 #include "oops/recordComponent.hpp"
56 #include "oops/trainingData.hpp"
57 #include "prims/jvmtiImpl.hpp"
58 #include "prims/jvmtiRedefineClasses.hpp"
59 #include "prims/jvmtiThreadState.inline.hpp"
60 #include "prims/methodComparator.hpp"
61 #include "prims/resolvedMethodTable.hpp"
62 #include "runtime/atomicAccess.hpp"
63 #include "runtime/deoptimization.hpp"
64 #include "runtime/handles.inline.hpp"
65 #include "runtime/jniHandles.inline.hpp"
66 #include "runtime/relocator.hpp"
67 #include "runtime/safepointVerifiers.hpp"
68 #include "utilities/bitMap.inline.hpp"
69 #include "utilities/checkedCast.hpp"
70 #include "utilities/events.hpp"
71 #include "utilities/macros.hpp"
72 #if INCLUDE_JFR
73 #include "jfr/jfr.hpp"
74 #endif
75
76 Array<Method*>* VM_RedefineClasses::_old_methods = nullptr;
77 Array<Method*>* VM_RedefineClasses::_new_methods = nullptr;
78 Method** VM_RedefineClasses::_matching_old_methods = nullptr;
79 Method** VM_RedefineClasses::_matching_new_methods = nullptr;
80 Method** VM_RedefineClasses::_deleted_methods = nullptr;
81 Method** VM_RedefineClasses::_added_methods = nullptr;
82 int VM_RedefineClasses::_matching_methods_length = 0;
83 int VM_RedefineClasses::_deleted_methods_length = 0;
84 int VM_RedefineClasses::_added_methods_length = 0;
85
86 // This flag is global as the constructor does not reset it:
87 bool VM_RedefineClasses::_has_redefined_Object = false;
88 u8 VM_RedefineClasses::_id_counter = 0;
89
90 VM_RedefineClasses::VM_RedefineClasses(jint class_count,
91 const jvmtiClassDefinition *class_defs,
92 JvmtiClassLoadKind class_load_kind) {
93 _class_count = class_count;
94 _class_defs = class_defs;
95 _class_load_kind = class_load_kind;
96 _any_class_has_resolved_methods = false;
97 _res = JVMTI_ERROR_NONE;
98 _the_class = nullptr;
99 _id = next_id();
100 }
101
102 static inline InstanceKlass* get_ik(jclass def) {
103 oop mirror = JNIHandles::resolve_non_null(def);
104 return java_lang_Class::as_InstanceKlass(mirror);
105 }
106
107 // If any of the classes are being redefined, wait
108 // Parallel constant pool merging leads to indeterminate constant pools.
109 void VM_RedefineClasses::lock_classes() {
110 JvmtiThreadState *state = JvmtiThreadState::state_for(JavaThread::current());
111 GrowableArray<Klass*>* redef_classes = state->get_classes_being_redefined();
112
113 MonitorLocker ml(RedefineClasses_lock);
114
115 if (redef_classes == nullptr) {
116 redef_classes = new (mtClass) GrowableArray<Klass*>(1, mtClass);
117 state->set_classes_being_redefined(redef_classes);
118 }
119
120 bool has_redefined;
121 do {
122 has_redefined = false;
123 // Go through classes each time until none are being redefined. Skip
124 // the ones that are being redefined by this thread currently. Class file
125 // load hook event may trigger new class redefine when we are redefining
126 // a class (after lock_classes()).
127 for (int i = 0; i < _class_count; i++) {
128 InstanceKlass* ik = get_ik(_class_defs[i].klass);
129 // Check if we are currently redefining the class in this thread already.
130 if (redef_classes->contains(ik)) {
131 assert(ik->is_being_redefined(), "sanity");
132 } else {
133 if (ik->is_being_redefined()) {
134 ml.wait();
135 has_redefined = true;
136 break; // for loop
137 }
138 }
139 }
140 } while (has_redefined);
141
142 for (int i = 0; i < _class_count; i++) {
143 InstanceKlass* ik = get_ik(_class_defs[i].klass);
144 redef_classes->push(ik); // Add to the _classes_being_redefined list
145 ik->set_is_being_redefined(true);
146 }
147 ml.notify_all();
148 }
149
150 void VM_RedefineClasses::unlock_classes() {
151 JvmtiThreadState *state = JvmtiThreadState::state_for(JavaThread::current());
152 GrowableArray<Klass*>* redef_classes = state->get_classes_being_redefined();
153 assert(redef_classes != nullptr, "_classes_being_redefined is not allocated");
154
155 MonitorLocker ml(RedefineClasses_lock);
156
157 for (int i = _class_count - 1; i >= 0; i--) {
158 InstanceKlass* def_ik = get_ik(_class_defs[i].klass);
159 if (redef_classes->length() > 0) {
160 // Remove the class from _classes_being_redefined list
161 Klass* k = redef_classes->pop();
162 assert(def_ik == k, "unlocking wrong class");
163 }
164 assert(def_ik->is_being_redefined(),
165 "should be being redefined to get here");
166
167 // Unlock after we finish all redefines for this class within
168 // the thread. Same class can be pushed to the list multiple
169 // times (not more than once by each recursive redefinition).
170 if (!redef_classes->contains(def_ik)) {
171 def_ik->set_is_being_redefined(false);
172 }
173 }
174 ml.notify_all();
175 }
176
177 bool VM_RedefineClasses::doit_prologue() {
178 if (_class_count == 0) {
179 _res = JVMTI_ERROR_NONE;
180 return false;
181 }
182 if (_class_defs == nullptr) {
183 _res = JVMTI_ERROR_NULL_POINTER;
184 return false;
185 }
186
187 for (int i = 0; i < _class_count; i++) {
188 if (_class_defs[i].klass == nullptr) {
189 _res = JVMTI_ERROR_INVALID_CLASS;
190 return false;
191 }
192 if (_class_defs[i].class_byte_count == 0) {
193 _res = JVMTI_ERROR_INVALID_CLASS_FORMAT;
194 return false;
195 }
196 if (_class_defs[i].class_bytes == nullptr) {
197 _res = JVMTI_ERROR_NULL_POINTER;
198 return false;
199 }
200
201 oop mirror = JNIHandles::resolve_non_null(_class_defs[i].klass);
202 // classes for primitives, arrays, and hidden classes
203 // cannot be redefined.
204 if (!is_modifiable_class(mirror)) {
205 _res = JVMTI_ERROR_UNMODIFIABLE_CLASS;
206 return false;
207 }
208 }
209
210 // Start timer after all the sanity checks; not quite accurate, but
211 // better than adding a bunch of stop() calls.
212 if (log_is_enabled(Info, redefine, class, timer)) {
213 _timer_vm_op_prologue.start();
214 }
215
216 lock_classes();
217 // We first load new class versions in the prologue, because somewhere down the
218 // call chain it is required that the current thread is a Java thread.
219 _res = load_new_class_versions();
220 if (_res != JVMTI_ERROR_NONE) {
221 // free any successfully created classes, since none are redefined
222 for (int i = 0; i < _class_count; i++) {
223 if (_scratch_classes[i] != nullptr) {
224 ClassLoaderData* cld = _scratch_classes[i]->class_loader_data();
225 // Free the memory for this class at class unloading time. Not before
226 // because CMS might think this is still live.
227 InstanceKlass* ik = get_ik(_class_defs[i].klass);
228 if (ik->get_cached_class_file() == _scratch_classes[i]->get_cached_class_file()) {
229 // Don't double-free cached_class_file copied from the original class if error.
230 _scratch_classes[i]->set_cached_class_file(nullptr);
231 }
232 cld->add_to_deallocate_list(InstanceKlass::cast(_scratch_classes[i]));
233 }
234 }
235 // Free os::malloc allocated memory in load_new_class_version.
236 os::free(_scratch_classes);
237 _timer_vm_op_prologue.stop();
238 unlock_classes();
239 return false;
240 }
241
242 _timer_vm_op_prologue.stop();
243 return true;
244 }
245
246 void VM_RedefineClasses::doit() {
247 Thread* current = Thread::current();
248
249 if (log_is_enabled(Info, redefine, class, timer)) {
250 _timer_vm_op_doit.start();
251 }
252
253 #if INCLUDE_CDS
254 if (CDSConfig::is_using_archive()) {
255 // Sharing is enabled so we remap the shared readonly space to
256 // shared readwrite, private just in case we need to redefine
257 // a shared class. We do the remap during the doit() phase of
258 // the safepoint to be safer.
259 if (!AOTMetaspace::remap_shared_readonly_as_readwrite()) {
260 log_info(redefine, class, load)("failed to remap shared readonly space to readwrite, private");
261 _res = JVMTI_ERROR_INTERNAL;
262 _timer_vm_op_doit.stop();
263 return;
264 }
265 }
266 #endif
267
268 // Mark methods seen on stack and everywhere else so old methods are not
269 // cleaned up if they're on the stack.
270 MetadataOnStackMark md_on_stack(/*walk_all_metadata*/true, /*redefinition_walk*/true);
271 HandleMark hm(current); // make sure any handles created are deleted
272 // before the stack walk again.
273
274 for (int i = 0; i < _class_count; i++) {
275 redefine_single_class(current, _class_defs[i].klass, _scratch_classes[i]);
276 }
277
278 #if INCLUDE_CDS
279 TrainingData::cleanup_after_redefinition();
280 #endif
281
282 // Flush all compiled code that depends on the classes redefined.
283 flush_dependent_code();
284
285 // Adjust constantpool caches and vtables for all classes
286 // that reference methods of the evolved classes.
287 // Have to do this after all classes are redefined and all methods that
288 // are redefined are marked as old.
289 AdjustAndCleanMetadata adjust_and_clean_metadata(current);
290 ClassLoaderDataGraph::classes_do(&adjust_and_clean_metadata);
291
292 // JSR-292 support
293 if (_any_class_has_resolved_methods) {
294 bool trace_name_printed = false;
295 ResolvedMethodTable::adjust_method_entries(&trace_name_printed);
296 }
297
298 // Increment flag indicating that some invariants are no longer true.
299 // See jvmtiExport.hpp for detailed explanation.
300 JvmtiExport::increment_redefinition_count();
301
302 // check_class() is optionally called for product bits, but is
303 // always called for non-product bits.
304 #ifdef PRODUCT
305 if (log_is_enabled(Trace, redefine, class, obsolete, metadata)) {
306 #endif
307 log_trace(redefine, class, obsolete, metadata)("calling check_class");
308 CheckClass check_class(current);
309 ClassLoaderDataGraph::classes_do(&check_class);
310 #ifdef PRODUCT
311 }
312 #endif
313
314 // Clean up any metadata now unreferenced while MetadataOnStackMark is set.
315 ClassLoaderDataGraph::clean_deallocate_lists(false);
316
317 _timer_vm_op_doit.stop();
318 }
319
320 void VM_RedefineClasses::doit_epilogue() {
321 unlock_classes();
322
323 // Free os::malloc allocated memory.
324 os::free(_scratch_classes);
325
326 // Reset the_class to null for error printing.
327 _the_class = nullptr;
328
329 if (log_is_enabled(Info, redefine, class, timer)) {
330 // Used to have separate timers for "doit" and "all", but the timer
331 // overhead skewed the measurements.
332 julong doit_time = _timer_vm_op_doit.milliseconds();
333 julong all_time = _timer_vm_op_prologue.milliseconds() + doit_time;
334
335 log_info(redefine, class, timer)
336 ("vm_op: all=" JULONG_FORMAT " prologue=" JULONG_FORMAT " doit=" JULONG_FORMAT,
337 all_time, (julong)_timer_vm_op_prologue.milliseconds(), doit_time);
338 log_info(redefine, class, timer)
339 ("redefine_single_class: phase1=" JULONG_FORMAT " phase2=" JULONG_FORMAT,
340 (julong)_timer_rsc_phase1.milliseconds(), (julong)_timer_rsc_phase2.milliseconds());
341 }
342 }
343
344 bool VM_RedefineClasses::is_modifiable_class(oop klass_mirror) {
345 // classes for primitives cannot be redefined
346 if (java_lang_Class::is_primitive(klass_mirror)) {
347 return false;
348 }
349 Klass* k = java_lang_Class::as_Klass(klass_mirror);
350 // classes for arrays cannot be redefined
351 if (k == nullptr || !k->is_instance_klass()) {
352 return false;
353 }
354
355 // Cannot redefine or retransform a hidden class.
356 if (InstanceKlass::cast(k)->is_hidden()) {
357 return false;
358 }
359 if (InstanceKlass::cast(k) == vmClasses::Continuation_klass()) {
360 // Don't redefine Continuation class. See 8302779.
361 return false;
362 }
363 return true;
364 }
365
366 // Append the current entry at scratch_i in scratch_cp to *merge_cp_p
367 // where the end of *merge_cp_p is specified by *merge_cp_length_p. For
368 // direct CP entries, there is just the current entry to append. For
369 // indirect and double-indirect CP entries, there are zero or more
370 // referenced CP entries along with the current entry to append.
371 // Indirect and double-indirect CP entries are handled by recursive
372 // calls to append_entry() as needed. The referenced CP entries are
373 // always appended to *merge_cp_p before the referee CP entry. These
374 // referenced CP entries may already exist in *merge_cp_p in which case
375 // there is nothing extra to append and only the current entry is
376 // appended.
377 void VM_RedefineClasses::append_entry(const constantPoolHandle& scratch_cp,
378 int scratch_i, constantPoolHandle *merge_cp_p, int *merge_cp_length_p) {
379
380 // append is different depending on entry tag type
381 switch (scratch_cp->tag_at(scratch_i).value()) {
382
383 // The old verifier is implemented outside the VM. It loads classes,
384 // but does not resolve constant pool entries directly so we never
385 // see Class entries here with the old verifier. Similarly the old
386 // verifier does not like Class entries in the input constant pool.
387 // The split-verifier is implemented in the VM so it can optionally
388 // and directly resolve constant pool entries to load classes. The
389 // split-verifier can accept either Class entries or UnresolvedClass
390 // entries in the input constant pool. We revert the appended copy
391 // back to UnresolvedClass so that either verifier will be happy
392 // with the constant pool entry.
393 //
394 // this is an indirect CP entry so it needs special handling
395 case JVM_CONSTANT_Class:
396 case JVM_CONSTANT_UnresolvedClass:
397 {
398 int name_i = scratch_cp->klass_name_index_at(scratch_i);
399 int new_name_i = find_or_append_indirect_entry(scratch_cp, name_i, merge_cp_p,
400 merge_cp_length_p);
401
402 if (new_name_i != name_i) {
403 log_trace(redefine, class, constantpool)
404 ("Class entry@%d name_index change: %d to %d",
405 *merge_cp_length_p, name_i, new_name_i);
406 }
407
408 (*merge_cp_p)->temp_unresolved_klass_at_put(*merge_cp_length_p, new_name_i);
409 if (scratch_i != *merge_cp_length_p) {
410 // The new entry in *merge_cp_p is at a different index than
411 // the new entry in scratch_cp so we need to map the index values.
412 map_index(scratch_cp, scratch_i, *merge_cp_length_p);
413 }
414 (*merge_cp_length_p)++;
415 } break;
416
417 // these are direct CP entries so they can be directly appended,
418 // but double and long take two constant pool entries
419 case JVM_CONSTANT_Double: // fall through
420 case JVM_CONSTANT_Long:
421 {
422 ConstantPool::copy_entry_to(scratch_cp, scratch_i, *merge_cp_p, *merge_cp_length_p);
423
424 if (scratch_i != *merge_cp_length_p) {
425 // The new entry in *merge_cp_p is at a different index than
426 // the new entry in scratch_cp so we need to map the index values.
427 map_index(scratch_cp, scratch_i, *merge_cp_length_p);
428 }
429 (*merge_cp_length_p) += 2;
430 } break;
431
432 // these are direct CP entries so they can be directly appended
433 case JVM_CONSTANT_Float: // fall through
434 case JVM_CONSTANT_Integer: // fall through
435 case JVM_CONSTANT_Utf8: // fall through
436
437 // This was an indirect CP entry, but it has been changed into
438 // Symbol*s so this entry can be directly appended.
439 case JVM_CONSTANT_String: // fall through
440 {
441 ConstantPool::copy_entry_to(scratch_cp, scratch_i, *merge_cp_p, *merge_cp_length_p);
442
443 if (scratch_i != *merge_cp_length_p) {
444 // The new entry in *merge_cp_p is at a different index than
445 // the new entry in scratch_cp so we need to map the index values.
446 map_index(scratch_cp, scratch_i, *merge_cp_length_p);
447 }
448 (*merge_cp_length_p)++;
449 } break;
450
451 // this is an indirect CP entry so it needs special handling
452 case JVM_CONSTANT_NameAndType:
453 {
454 int name_ref_i = scratch_cp->name_ref_index_at(scratch_i);
455 int new_name_ref_i = find_or_append_indirect_entry(scratch_cp, name_ref_i, merge_cp_p,
456 merge_cp_length_p);
457
458 int signature_ref_i = scratch_cp->signature_ref_index_at(scratch_i);
459 int new_signature_ref_i = find_or_append_indirect_entry(scratch_cp, signature_ref_i,
460 merge_cp_p, merge_cp_length_p);
461
462 // If the referenced entries already exist in *merge_cp_p, then
463 // both new_name_ref_i and new_signature_ref_i will both be 0.
464 // In that case, all we are appending is the current entry.
465 if (new_name_ref_i != name_ref_i) {
466 log_trace(redefine, class, constantpool)
467 ("NameAndType entry@%d name_ref_index change: %d to %d",
468 *merge_cp_length_p, name_ref_i, new_name_ref_i);
469 }
470 if (new_signature_ref_i != signature_ref_i) {
471 log_trace(redefine, class, constantpool)
472 ("NameAndType entry@%d signature_ref_index change: %d to %d",
473 *merge_cp_length_p, signature_ref_i, new_signature_ref_i);
474 }
475
476 (*merge_cp_p)->name_and_type_at_put(*merge_cp_length_p,
477 new_name_ref_i, new_signature_ref_i);
478 if (scratch_i != *merge_cp_length_p) {
479 // The new entry in *merge_cp_p is at a different index than
480 // the new entry in scratch_cp so we need to map the index values.
481 map_index(scratch_cp, scratch_i, *merge_cp_length_p);
482 }
483 (*merge_cp_length_p)++;
484 } break;
485
486 // this is a double-indirect CP entry so it needs special handling
487 case JVM_CONSTANT_Fieldref: // fall through
488 case JVM_CONSTANT_InterfaceMethodref: // fall through
489 case JVM_CONSTANT_Methodref:
490 {
491 int klass_ref_i = scratch_cp->uncached_klass_ref_index_at(scratch_i);
492 int new_klass_ref_i = find_or_append_indirect_entry(scratch_cp, klass_ref_i,
493 merge_cp_p, merge_cp_length_p);
494
495 int name_and_type_ref_i = scratch_cp->uncached_name_and_type_ref_index_at(scratch_i);
496 int new_name_and_type_ref_i = find_or_append_indirect_entry(scratch_cp, name_and_type_ref_i,
497 merge_cp_p, merge_cp_length_p);
498
499 const char *entry_name = nullptr;
500 switch (scratch_cp->tag_at(scratch_i).value()) {
501 case JVM_CONSTANT_Fieldref:
502 entry_name = "Fieldref";
503 (*merge_cp_p)->field_at_put(*merge_cp_length_p, new_klass_ref_i,
504 new_name_and_type_ref_i);
505 break;
506 case JVM_CONSTANT_InterfaceMethodref:
507 entry_name = "IFMethodref";
508 (*merge_cp_p)->interface_method_at_put(*merge_cp_length_p,
509 new_klass_ref_i, new_name_and_type_ref_i);
510 break;
511 case JVM_CONSTANT_Methodref:
512 entry_name = "Methodref";
513 (*merge_cp_p)->method_at_put(*merge_cp_length_p, new_klass_ref_i,
514 new_name_and_type_ref_i);
515 break;
516 default:
517 guarantee(false, "bad switch");
518 break;
519 }
520
521 if (klass_ref_i != new_klass_ref_i) {
522 log_trace(redefine, class, constantpool)
523 ("%s entry@%d class_index changed: %d to %d", entry_name, *merge_cp_length_p, klass_ref_i, new_klass_ref_i);
524 }
525 if (name_and_type_ref_i != new_name_and_type_ref_i) {
526 log_trace(redefine, class, constantpool)
527 ("%s entry@%d name_and_type_index changed: %d to %d",
528 entry_name, *merge_cp_length_p, name_and_type_ref_i, new_name_and_type_ref_i);
529 }
530
531 if (scratch_i != *merge_cp_length_p) {
532 // The new entry in *merge_cp_p is at a different index than
533 // the new entry in scratch_cp so we need to map the index values.
534 map_index(scratch_cp, scratch_i, *merge_cp_length_p);
535 }
536 (*merge_cp_length_p)++;
537 } break;
538
539 // this is an indirect CP entry so it needs special handling
540 case JVM_CONSTANT_MethodType:
541 {
542 int ref_i = scratch_cp->method_type_index_at(scratch_i);
543 int new_ref_i = find_or_append_indirect_entry(scratch_cp, ref_i, merge_cp_p,
544 merge_cp_length_p);
545 if (new_ref_i != ref_i) {
546 log_trace(redefine, class, constantpool)
547 ("MethodType entry@%d ref_index change: %d to %d", *merge_cp_length_p, ref_i, new_ref_i);
548 }
549 (*merge_cp_p)->method_type_index_at_put(*merge_cp_length_p, new_ref_i);
550 if (scratch_i != *merge_cp_length_p) {
551 // The new entry in *merge_cp_p is at a different index than
552 // the new entry in scratch_cp so we need to map the index values.
553 map_index(scratch_cp, scratch_i, *merge_cp_length_p);
554 }
555 (*merge_cp_length_p)++;
556 } break;
557
558 // this is an indirect CP entry so it needs special handling
559 case JVM_CONSTANT_MethodHandle:
560 {
561 int ref_kind = scratch_cp->method_handle_ref_kind_at(scratch_i);
562 int ref_i = scratch_cp->method_handle_index_at(scratch_i);
563 int new_ref_i = find_or_append_indirect_entry(scratch_cp, ref_i, merge_cp_p,
564 merge_cp_length_p);
565 if (new_ref_i != ref_i) {
566 log_trace(redefine, class, constantpool)
567 ("MethodHandle entry@%d ref_index change: %d to %d", *merge_cp_length_p, ref_i, new_ref_i);
568 }
569 (*merge_cp_p)->method_handle_index_at_put(*merge_cp_length_p, ref_kind, new_ref_i);
570 if (scratch_i != *merge_cp_length_p) {
571 // The new entry in *merge_cp_p is at a different index than
572 // the new entry in scratch_cp so we need to map the index values.
573 map_index(scratch_cp, scratch_i, *merge_cp_length_p);
574 }
575 (*merge_cp_length_p)++;
576 } break;
577
578 // this is an indirect CP entry so it needs special handling
579 case JVM_CONSTANT_Dynamic: // fall through
580 case JVM_CONSTANT_InvokeDynamic:
581 {
582 // Index of the bootstrap specifier in the BSM array
583 int old_bs_i = scratch_cp->bootstrap_methods_attribute_index(scratch_i);
584 int new_bs_i = find_or_append_bsm_entry(scratch_cp, old_bs_i, merge_cp_p,
585 merge_cp_length_p);
586 // The bootstrap method NameAndType_info index
587 int old_ref_i = scratch_cp->bootstrap_name_and_type_ref_index_at(scratch_i);
588 int new_ref_i = find_or_append_indirect_entry(scratch_cp, old_ref_i, merge_cp_p,
589 merge_cp_length_p);
590 if (new_bs_i != old_bs_i) {
591 log_trace(redefine, class, constantpool)
592 ("Dynamic entry@%d bootstrap_method_attr_index change: %d to %d",
593 *merge_cp_length_p, old_bs_i, new_bs_i);
594 }
595 if (new_ref_i != old_ref_i) {
596 log_trace(redefine, class, constantpool)
597 ("Dynamic entry@%d name_and_type_index change: %d to %d", *merge_cp_length_p, old_ref_i, new_ref_i);
598 }
599
600 if (scratch_cp->tag_at(scratch_i).is_dynamic_constant()) {
601 (*merge_cp_p)->dynamic_constant_at_put(*merge_cp_length_p, new_bs_i, new_ref_i);
602 } else {
603 (*merge_cp_p)->invoke_dynamic_at_put(*merge_cp_length_p, new_bs_i, new_ref_i);
604 }
605 if (scratch_i != *merge_cp_length_p) {
606 // The new entry in *merge_cp_p is at a different index than
607 // the new entry in scratch_cp so we need to map the index values.
608 map_index(scratch_cp, scratch_i, *merge_cp_length_p);
609 }
610 (*merge_cp_length_p)++;
611 } break;
612
613 // At this stage, Class or UnresolvedClass could be in scratch_cp, but not
614 // ClassIndex
615 case JVM_CONSTANT_ClassIndex: // fall through
616
617 // Invalid is used as the tag for the second constant pool entry
618 // occupied by JVM_CONSTANT_Double or JVM_CONSTANT_Long. It should
619 // not be seen by itself.
620 case JVM_CONSTANT_Invalid: // fall through
621
622 // At this stage, String could be here, but not StringIndex
623 case JVM_CONSTANT_StringIndex: // fall through
624
625 // At this stage JVM_CONSTANT_UnresolvedClassInError should not be here
626 case JVM_CONSTANT_UnresolvedClassInError: // fall through
627
628 default:
629 {
630 // leave a breadcrumb
631 jbyte bad_value = scratch_cp->tag_at(scratch_i).value();
632 ShouldNotReachHere();
633 } break;
634 } // end switch tag value
635 } // end append_entry()
636
637
638 u2 VM_RedefineClasses::find_or_append_indirect_entry(const constantPoolHandle& scratch_cp,
639 int ref_i, constantPoolHandle *merge_cp_p, int *merge_cp_length_p) {
640
641 int new_ref_i = ref_i;
642 bool match = (ref_i < *merge_cp_length_p) &&
643 scratch_cp->compare_entry_to(ref_i, *merge_cp_p, ref_i);
644
645 if (!match) {
646 // forward reference in *merge_cp_p or not a direct match
647 int found_i = scratch_cp->find_matching_entry(ref_i, *merge_cp_p);
648 if (found_i != 0) {
649 guarantee(found_i != ref_i, "compare_entry_to() and find_matching_entry() do not agree");
650 // Found a matching entry somewhere else in *merge_cp_p so just need a mapping entry.
651 new_ref_i = found_i;
652 map_index(scratch_cp, ref_i, found_i);
653 } else {
654 // no match found so we have to append this entry to *merge_cp_p
655 append_entry(scratch_cp, ref_i, merge_cp_p, merge_cp_length_p);
656 // The above call to append_entry() can only append one entry
657 // so the post call query of *merge_cp_length_p is only for
658 // the sake of consistency.
659 new_ref_i = *merge_cp_length_p - 1;
660 }
661 }
662
663 // constant pool indices are u2, unless the merged constant pool overflows which
664 // we don't check for.
665 return checked_cast<u2>(new_ref_i);
666 } // end find_or_append_indirect_entry()
667
668
669 // Append a bootstrap specifier into the merge_cp BSM entries that is semantically equal
670 // to the scratch_cp BSM entries' bootstrap specifier passed by the old_bs_i index.
671 // Recursively append new merge_cp entries referenced by the new bootstrap specifier.
672 int VM_RedefineClasses::append_bsm_entry(const constantPoolHandle& scratch_cp, const int old_bs_i,
673 constantPoolHandle *merge_cp_p, int *merge_cp_length_p) {
674
675 BSMAttributeEntry* old_bsme = scratch_cp->bsm_attribute_entry(old_bs_i);
676 u2 old_ref_i = old_bsme->bootstrap_method_index();
677 u2 new_ref_i = find_or_append_indirect_entry(scratch_cp, old_ref_i, merge_cp_p,
678 merge_cp_length_p);
679 if (new_ref_i != old_ref_i) {
680 log_trace(redefine, class, constantpool)
681 ("BSM attribute entry@%d bootstrap method ref_index change: %d to %d", _bsmae_iter.current_offset() - 1, old_ref_i, new_ref_i);
682 }
683
684 const int new_bs_i = _bsmae_iter.current_offset();
685 BSMAttributeEntry* new_bsme =
686 _bsmae_iter.reserve_new_entry(new_ref_i, old_bsme->argument_count());
687 assert(new_bsme != nullptr, "must be");
688 for (int i = 0; i < new_bsme->argument_count(); i++) {
689 u2 old_arg_ref_i = old_bsme->argument(i);
690 u2 new_arg_ref_i = find_or_append_indirect_entry(scratch_cp, old_arg_ref_i, merge_cp_p,
691 merge_cp_length_p);
692 new_bsme->set_argument(i, new_arg_ref_i);
693
694 if (new_arg_ref_i != old_arg_ref_i) {
695 log_trace(redefine, class, constantpool)
696 ("BSM attribute entry@%d bootstrap method argument ref_index change: %d to %d",
697 _bsmae_iter.current_offset() - 1, old_arg_ref_i, new_arg_ref_i);
698 }
699 }
700 // This is only for the logging
701 map_bsm_index(old_bs_i, new_bs_i);
702 return new_bs_i;
703 } // end append_bsm_entry()
704
705
706 int VM_RedefineClasses::find_or_append_bsm_entry(const constantPoolHandle& scratch_cp,
707 int old_bs_i, constantPoolHandle *merge_cp_p, int *merge_cp_length_p) {
708
709 const int max_offset_in_merge = _bsmae_iter.current_offset();
710 int new_bs_i = old_bs_i; // bootstrap specifier index
711 // Has the old_bs_i index been used already? Check if it's the same so we know
712 // whether or not a remapping is required.
713 bool match = (old_bs_i < max_offset_in_merge) &&
714 scratch_cp->compare_bootstrap_entry_to(old_bs_i, *merge_cp_p, old_bs_i);
715
716 if (!match) {
717 // forward reference in *merge_cp_p or not a direct match
718 int found_i = scratch_cp->find_matching_bsm_entry(old_bs_i, *merge_cp_p,
719 max_offset_in_merge);
720 if (found_i != -1) {
721 guarantee(found_i != old_bs_i, "compare_bootstrap_entry_to() and find_matching_bsm_entry() disagree");
722 // found a matching BSM entry somewhere else in *merge_cp_p so just need a mapping
723 new_bs_i = found_i;
724 map_bsm_index(old_bs_i, found_i);
725 } else {
726 // no match found so we have to append this bootstrap specifier to *merge_cp_p
727 new_bs_i = append_bsm_entry(scratch_cp, old_bs_i, merge_cp_p, merge_cp_length_p);
728 }
729 }
730 return new_bs_i;
731 } // end find_or_append_bsm_entry()
732
733
734 void VM_RedefineClasses::finalize_bsm_entries_merge(const constantPoolHandle& merge_cp, TRAPS) {
735 if (merge_cp->bsm_entries().number_of_entries() == 0) {
736 return;
737 }
738 // Finished extending the BSMAEs
739 merge_cp->end_extension(_bsmae_iter, CHECK);
740
741 if (log_is_enabled(Trace, redefine, class, constantpool)) {
742 // don't want to loop unless we are tracing
743 int count = 0;
744 for (int i = 1; i < _bsm_index_map_p->length(); i++) {
745 int value = _bsm_index_map_p->at(i);
746 if (value != -1) {
747 log_trace(redefine, class, constantpool)("bsm_index_map[%d]: old=%d new=%d", count, i, value);
748 count++;
749 }
750 }
751 }
752 // Clean-up
753 _bsm_index_map_p = nullptr;
754 _bsm_index_map_count = 0;
755 _bsmae_iter = BSMAttributeEntries::InsertionIterator();
756 } // end finalize_bsmentries_merge()
757
758 // Symbol* comparator for qsort
759 // The caller must have an active ResourceMark.
760 static int symcmp(const void* a, const void* b) {
761 char* astr = (*(Symbol**)a)->as_C_string();
762 char* bstr = (*(Symbol**)b)->as_C_string();
763 return strcmp(astr, bstr);
764 }
765
766 // The caller must have an active ResourceMark.
767 static jvmtiError check_attribute_arrays(const char* attr_name,
768 InstanceKlass* the_class, InstanceKlass* scratch_class,
769 Array<u2>* the_array, Array<u2>* scr_array) {
770 bool the_array_exists = the_array != Universe::the_empty_short_array();
771 bool scr_array_exists = scr_array != Universe::the_empty_short_array();
772
773 int array_len = the_array->length();
774 if (the_array_exists && scr_array_exists) {
775 if (array_len != scr_array->length()) {
776 log_trace(redefine, class)
777 ("redefined class %s attribute change error: %s len=%d changed to len=%d",
778 the_class->external_name(), attr_name, array_len, scr_array->length());
779 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_CLASS_ATTRIBUTE_CHANGED;
780 }
781
782 // The order of entries in the attribute array is not specified so we
783 // have to explicitly check for the same contents. We do this by copying
784 // the referenced symbols into their own arrays, sorting them and then
785 // comparing each element pair.
786
787 Symbol** the_syms = NEW_RESOURCE_ARRAY_RETURN_NULL(Symbol*, array_len);
788 Symbol** scr_syms = NEW_RESOURCE_ARRAY_RETURN_NULL(Symbol*, array_len);
789
790 if (the_syms == nullptr || scr_syms == nullptr) {
791 return JVMTI_ERROR_OUT_OF_MEMORY;
792 }
793
794 for (int i = 0; i < array_len; i++) {
795 int the_cp_index = the_array->at(i);
796 int scr_cp_index = scr_array->at(i);
797 the_syms[i] = the_class->constants()->klass_name_at(the_cp_index);
798 scr_syms[i] = scratch_class->constants()->klass_name_at(scr_cp_index);
799 }
800
801 qsort(the_syms, array_len, sizeof(Symbol*), symcmp);
802 qsort(scr_syms, array_len, sizeof(Symbol*), symcmp);
803
804 for (int i = 0; i < array_len; i++) {
805 if (the_syms[i] != scr_syms[i]) {
806 log_info(redefine, class)
807 ("redefined class %s attribute change error: %s[%d]: %s changed to %s",
808 the_class->external_name(), attr_name, i,
809 the_syms[i]->as_C_string(), scr_syms[i]->as_C_string());
810 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_CLASS_ATTRIBUTE_CHANGED;
811 }
812 }
813 } else if (the_array_exists ^ scr_array_exists) {
814 const char* action_str = (the_array_exists) ? "removed" : "added";
815 log_info(redefine, class)
816 ("redefined class %s attribute change error: %s attribute %s",
817 the_class->external_name(), attr_name, action_str);
818 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_CLASS_ATTRIBUTE_CHANGED;
819 }
820 return JVMTI_ERROR_NONE;
821 }
822
823 static jvmtiError check_nest_attributes(InstanceKlass* the_class,
824 InstanceKlass* scratch_class) {
825 // Check whether the class NestHost attribute has been changed.
826 Thread* thread = Thread::current();
827 ResourceMark rm(thread);
828 u2 the_nest_host_idx = the_class->nest_host_index();
829 u2 scr_nest_host_idx = scratch_class->nest_host_index();
830
831 if (the_nest_host_idx != 0 && scr_nest_host_idx != 0) {
832 Symbol* the_sym = the_class->constants()->klass_name_at(the_nest_host_idx);
833 Symbol* scr_sym = scratch_class->constants()->klass_name_at(scr_nest_host_idx);
834 if (the_sym != scr_sym) {
835 log_info(redefine, class, nestmates)
836 ("redefined class %s attribute change error: NestHost class: %s replaced with: %s",
837 the_class->external_name(), the_sym->as_C_string(), scr_sym->as_C_string());
838 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_CLASS_ATTRIBUTE_CHANGED;
839 }
840 } else if ((the_nest_host_idx == 0) ^ (scr_nest_host_idx == 0)) {
841 const char* action_str = (the_nest_host_idx != 0) ? "removed" : "added";
842 log_info(redefine, class, nestmates)
843 ("redefined class %s attribute change error: NestHost attribute %s",
844 the_class->external_name(), action_str);
845 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_CLASS_ATTRIBUTE_CHANGED;
846 }
847
848 // Check whether the class NestMembers attribute has been changed.
849 return check_attribute_arrays("NestMembers",
850 the_class, scratch_class,
851 the_class->nest_members(),
852 scratch_class->nest_members());
853 }
854
855 // Return an error status if the class Record attribute was changed.
856 static jvmtiError check_record_attribute(InstanceKlass* the_class, InstanceKlass* scratch_class) {
857 // Get lists of record components.
858 Array<RecordComponent*>* the_record = the_class->record_components();
859 Array<RecordComponent*>* scr_record = scratch_class->record_components();
860 bool the_record_exists = the_record != nullptr;
861 bool scr_record_exists = scr_record != nullptr;
862
863 if (the_record_exists && scr_record_exists) {
864 int the_num_components = the_record->length();
865 int scr_num_components = scr_record->length();
866 if (the_num_components != scr_num_components) {
867 log_info(redefine, class, record)
868 ("redefined class %s attribute change error: Record num_components=%d changed to num_components=%d",
869 the_class->external_name(), the_num_components, scr_num_components);
870 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_CLASS_ATTRIBUTE_CHANGED;
871 }
872
873 // Compare each field in each record component.
874 ConstantPool* the_cp = the_class->constants();
875 ConstantPool* scr_cp = scratch_class->constants();
876 for (int x = 0; x < the_num_components; x++) {
877 RecordComponent* the_component = the_record->at(x);
878 RecordComponent* scr_component = scr_record->at(x);
879 const Symbol* const the_name = the_cp->symbol_at(the_component->name_index());
880 const Symbol* const scr_name = scr_cp->symbol_at(scr_component->name_index());
881 const Symbol* const the_descr = the_cp->symbol_at(the_component->descriptor_index());
882 const Symbol* const scr_descr = scr_cp->symbol_at(scr_component->descriptor_index());
883 if (the_name != scr_name || the_descr != scr_descr) {
884 log_info(redefine, class, record)
885 ("redefined class %s attribute change error: Record name_index, descriptor_index, and/or attributes_count changed",
886 the_class->external_name());
887 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_CLASS_ATTRIBUTE_CHANGED;
888 }
889
890 int the_gen_sig = the_component->generic_signature_index();
891 int scr_gen_sig = scr_component->generic_signature_index();
892 const Symbol* const the_gen_sig_sym = (the_gen_sig == 0 ? nullptr :
893 the_cp->symbol_at(the_component->generic_signature_index()));
894 const Symbol* const scr_gen_sig_sym = (scr_gen_sig == 0 ? nullptr :
895 scr_cp->symbol_at(scr_component->generic_signature_index()));
896 if (the_gen_sig_sym != scr_gen_sig_sym) {
897 log_info(redefine, class, record)
898 ("redefined class %s attribute change error: Record generic_signature attribute changed",
899 the_class->external_name());
900 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_CLASS_ATTRIBUTE_CHANGED;
901 }
902
903 // It's okay if a record component's annotations were changed.
904 }
905
906 } else if (the_record_exists ^ scr_record_exists) {
907 const char* action_str = (the_record_exists) ? "removed" : "added";
908 log_info(redefine, class, record)
909 ("redefined class %s attribute change error: Record attribute %s",
910 the_class->external_name(), action_str);
911 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_CLASS_ATTRIBUTE_CHANGED;
912 }
913
914 return JVMTI_ERROR_NONE;
915 }
916
917
918 static jvmtiError check_permitted_subclasses_attribute(InstanceKlass* the_class,
919 InstanceKlass* scratch_class) {
920 Thread* thread = Thread::current();
921 ResourceMark rm(thread);
922
923 // Check whether the class PermittedSubclasses attribute has been changed.
924 return check_attribute_arrays("PermittedSubclasses",
925 the_class, scratch_class,
926 the_class->permitted_subclasses(),
927 scratch_class->permitted_subclasses());
928 }
929
930 static bool can_add_or_delete(Method* m) {
931 // Compatibility mode
932 return (AllowRedefinitionToAddDeleteMethods &&
933 (m->is_private() && (m->is_static() || m->is_final())));
934 }
935
936 jvmtiError VM_RedefineClasses::compare_and_normalize_class_versions(
937 InstanceKlass* the_class,
938 InstanceKlass* scratch_class) {
939 int i;
940
941 // Check superclasses, or rather their names, since superclasses themselves can be
942 // requested to replace.
943 // Check for null superclass first since this might be java.lang.Object
944 if (the_class->super() != scratch_class->super() &&
945 (the_class->super() == nullptr || scratch_class->super() == nullptr ||
946 the_class->super()->name() !=
947 scratch_class->super()->name())) {
948 log_info(redefine, class, normalize)
949 ("redefined class %s superclass change error: superclass changed from %s to %s.",
950 the_class->external_name(),
951 the_class->super() == nullptr ? "null" : the_class->super()->external_name(),
952 scratch_class->super() == nullptr ? "null" : scratch_class->super()->external_name());
953 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_HIERARCHY_CHANGED;
954 }
955
956 // Check if the number, names and order of directly implemented interfaces are the same.
957 // I think in principle we should just check if the sets of names of directly implemented
958 // interfaces are the same, i.e. the order of declaration (which, however, if changed in the
959 // .java file, also changes in .class file) should not matter. However, comparing sets is
960 // technically a bit more difficult, and, more importantly, I am not sure at present that the
961 // order of interfaces does not matter on the implementation level, i.e. that the VM does not
962 // rely on it somewhere.
963 Array<InstanceKlass*>* k_interfaces = the_class->local_interfaces();
964 Array<InstanceKlass*>* k_new_interfaces = scratch_class->local_interfaces();
965 int n_intfs = k_interfaces->length();
966 if (n_intfs != k_new_interfaces->length()) {
967 log_info(redefine, class, normalize)
968 ("redefined class %s interfaces change error: number of implemented interfaces changed from %d to %d.",
969 the_class->external_name(), n_intfs, k_new_interfaces->length());
970 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_HIERARCHY_CHANGED;
971 }
972 for (i = 0; i < n_intfs; i++) {
973 if (k_interfaces->at(i)->name() !=
974 k_new_interfaces->at(i)->name()) {
975 log_info(redefine, class, normalize)
976 ("redefined class %s interfaces change error: interface changed from %s to %s.",
977 the_class->external_name(),
978 k_interfaces->at(i)->external_name(), k_new_interfaces->at(i)->external_name());
979 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_HIERARCHY_CHANGED;
980 }
981 }
982
983 // Check whether class is in the error init state.
984 if (the_class->is_in_error_state()) {
985 log_info(redefine, class, normalize)
986 ("redefined class %s is in error init state.", the_class->external_name());
987 // TBD #5057930: special error code is needed in 1.6
988 return JVMTI_ERROR_INVALID_CLASS;
989 }
990
991 // Check whether the nest-related attributes have been changed.
992 jvmtiError err = check_nest_attributes(the_class, scratch_class);
993 if (err != JVMTI_ERROR_NONE) {
994 return err;
995 }
996
997 // Check whether the Record attribute has been changed.
998 err = check_record_attribute(the_class, scratch_class);
999 if (err != JVMTI_ERROR_NONE) {
1000 return err;
1001 }
1002
1003 // Check whether the PermittedSubclasses attribute has been changed.
1004 err = check_permitted_subclasses_attribute(the_class, scratch_class);
1005 if (err != JVMTI_ERROR_NONE) {
1006 return err;
1007 }
1008
1009 // Check whether class modifiers are the same.
1010 u2 old_flags = the_class->access_flags().as_class_flags();
1011 u2 new_flags = scratch_class->access_flags().as_class_flags();
1012 if (old_flags != new_flags) {
1013 log_info(redefine, class, normalize)
1014 ("redefined class %s modifiers change error: modifiers changed from %d to %d.",
1015 the_class->external_name(), old_flags, new_flags);
1016 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_CLASS_MODIFIERS_CHANGED;
1017 }
1018
1019 // Check if the number, names, types and order of fields declared in these classes
1020 // are the same.
1021 JavaFieldStream old_fs(the_class);
1022 JavaFieldStream new_fs(scratch_class);
1023 for (; !old_fs.done() && !new_fs.done(); old_fs.next(), new_fs.next()) {
1024 // name and signature
1025 Symbol* name_sym1 = the_class->constants()->symbol_at(old_fs.name_index());
1026 Symbol* sig_sym1 = the_class->constants()->symbol_at(old_fs.signature_index());
1027 Symbol* name_sym2 = scratch_class->constants()->symbol_at(new_fs.name_index());
1028 Symbol* sig_sym2 = scratch_class->constants()->symbol_at(new_fs.signature_index());
1029 if (name_sym1 != name_sym2 || sig_sym1 != sig_sym2) {
1030 log_info(redefine, class, normalize)
1031 ("redefined class %s fields change error: field %s %s changed to %s %s.",
1032 the_class->external_name(),
1033 sig_sym1->as_C_string(), name_sym1->as_C_string(),
1034 sig_sym2->as_C_string(), name_sym2->as_C_string());
1035 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_SCHEMA_CHANGED;
1036 }
1037 // offset
1038 if (old_fs.offset() != new_fs.offset()) {
1039 log_info(redefine, class, normalize)
1040 ("redefined class %s field %s change error: offset changed from %d to %d.",
1041 the_class->external_name(), name_sym2->as_C_string(), old_fs.offset(), new_fs.offset());
1042 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_SCHEMA_CHANGED;
1043 }
1044 // access
1045 old_flags = old_fs.access_flags().as_field_flags();
1046 new_flags = new_fs.access_flags().as_field_flags();
1047 if (old_flags != new_flags) {
1048 log_info(redefine, class, normalize)
1049 ("redefined class %s field %s change error: modifiers changed from %d to %d.",
1050 the_class->external_name(), name_sym2->as_C_string(), old_flags, new_flags);
1051 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_SCHEMA_CHANGED;
1052 }
1053 }
1054
1055 // If both streams aren't done then we have a differing number of
1056 // fields.
1057 if (!old_fs.done() || !new_fs.done()) {
1058 const char* action = old_fs.done() ? "added" : "deleted";
1059 log_info(redefine, class, normalize)
1060 ("redefined class %s fields change error: some fields were %s.",
1061 the_class->external_name(), action);
1062 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_SCHEMA_CHANGED;
1063 }
1064
1065 // Do a parallel walk through the old and new methods. Detect
1066 // cases where they match (exist in both), have been added in
1067 // the new methods, or have been deleted (exist only in the
1068 // old methods). The class file parser places methods in order
1069 // by method name, but does not order overloaded methods by
1070 // signature. In order to determine what fate befell the methods,
1071 // this code places the overloaded new methods that have matching
1072 // old methods in the same order as the old methods and places
1073 // new overloaded methods at the end of overloaded methods of
1074 // that name. The code for this order normalization is adapted
1075 // from the algorithm used in InstanceKlass::find_method().
1076 // Since we are swapping out of order entries as we find them,
1077 // we only have to search forward through the overloaded methods.
1078 // Methods which are added and have the same name as an existing
1079 // method (but different signature) will be put at the end of
1080 // the methods with that name, and the name mismatch code will
1081 // handle them.
1082 Array<Method*>* k_old_methods(the_class->methods());
1083 Array<Method*>* k_new_methods(scratch_class->methods());
1084 int n_old_methods = k_old_methods->length();
1085 int n_new_methods = k_new_methods->length();
1086 Thread* thread = Thread::current();
1087
1088 int ni = 0;
1089 int oi = 0;
1090 while (true) {
1091 Method* k_old_method;
1092 Method* k_new_method;
1093 enum { matched, added, deleted, undetermined } method_was = undetermined;
1094
1095 if (oi >= n_old_methods) {
1096 if (ni >= n_new_methods) {
1097 break; // we've looked at everything, done
1098 }
1099 // New method at the end
1100 k_new_method = k_new_methods->at(ni);
1101 method_was = added;
1102 } else if (ni >= n_new_methods) {
1103 // Old method, at the end, is deleted
1104 k_old_method = k_old_methods->at(oi);
1105 method_was = deleted;
1106 } else {
1107 // There are more methods in both the old and new lists
1108 k_old_method = k_old_methods->at(oi);
1109 k_new_method = k_new_methods->at(ni);
1110 if (k_old_method->name() != k_new_method->name()) {
1111 // Methods are sorted by method name, so a mismatch means added
1112 // or deleted
1113 if (k_old_method->name()->fast_compare(k_new_method->name()) > 0) {
1114 method_was = added;
1115 } else {
1116 method_was = deleted;
1117 }
1118 } else if (k_old_method->signature() == k_new_method->signature()) {
1119 // Both the name and signature match
1120 method_was = matched;
1121 } else {
1122 // The name matches, but the signature doesn't, which means we have to
1123 // search forward through the new overloaded methods.
1124 int nj; // outside the loop for post-loop check
1125 for (nj = ni + 1; nj < n_new_methods; nj++) {
1126 Method* m = k_new_methods->at(nj);
1127 if (k_old_method->name() != m->name()) {
1128 // reached another method name so no more overloaded methods
1129 method_was = deleted;
1130 break;
1131 }
1132 if (k_old_method->signature() == m->signature()) {
1133 // found a match so swap the methods
1134 k_new_methods->at_put(ni, m);
1135 k_new_methods->at_put(nj, k_new_method);
1136 k_new_method = m;
1137 method_was = matched;
1138 break;
1139 }
1140 }
1141
1142 if (nj >= n_new_methods) {
1143 // reached the end without a match; so method was deleted
1144 method_was = deleted;
1145 }
1146 }
1147 }
1148
1149 switch (method_was) {
1150 case matched:
1151 // methods match, be sure modifiers do too
1152 old_flags = k_old_method->access_flags().as_method_flags();
1153 new_flags = k_new_method->access_flags().as_method_flags();
1154 if ((old_flags ^ new_flags) & ~(JVM_ACC_NATIVE)) {
1155 log_info(redefine, class, normalize)
1156 ("redefined class %s method %s modifiers error: modifiers changed from %d to %d",
1157 the_class->external_name(), k_old_method->name_and_sig_as_C_string(), old_flags, new_flags);
1158 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_METHOD_MODIFIERS_CHANGED;
1159 }
1160 {
1161 u2 new_num = k_new_method->method_idnum();
1162 u2 old_num = k_old_method->method_idnum();
1163 if (new_num != old_num) {
1164 Method* idnum_owner = scratch_class->method_with_idnum(old_num);
1165 if (idnum_owner != nullptr) {
1166 // There is already a method assigned this idnum -- switch them
1167 // Take current and original idnum from the new_method
1168 idnum_owner->set_method_idnum(new_num);
1169 idnum_owner->set_orig_method_idnum(k_new_method->orig_method_idnum());
1170 }
1171 // Take current and original idnum from the old_method
1172 k_new_method->set_method_idnum(old_num);
1173 k_new_method->set_orig_method_idnum(k_old_method->orig_method_idnum());
1174 if (thread->has_pending_exception()) {
1175 return JVMTI_ERROR_OUT_OF_MEMORY;
1176 }
1177 }
1178 }
1179 log_trace(redefine, class, normalize)
1180 ("Method matched: new: %s [%d] == old: %s [%d]",
1181 k_new_method->name_and_sig_as_C_string(), ni, k_old_method->name_and_sig_as_C_string(), oi);
1182 // advance to next pair of methods
1183 ++oi;
1184 ++ni;
1185 break;
1186 case added:
1187 // method added, see if it is OK
1188 if (!can_add_or_delete(k_new_method)) {
1189 log_info(redefine, class, normalize)
1190 ("redefined class %s methods error: added method: %s [%d]",
1191 the_class->external_name(), k_new_method->name_and_sig_as_C_string(), ni);
1192 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_METHOD_ADDED;
1193 }
1194 {
1195 u2 num = the_class->next_method_idnum();
1196 if (num == ConstMethod::UNSET_IDNUM) {
1197 // cannot add any more methods
1198 log_info(redefine, class, normalize)
1199 ("redefined class %s methods error: can't create ID for new method %s [%d]",
1200 the_class->external_name(), k_new_method->name_and_sig_as_C_string(), ni);
1201 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_METHOD_ADDED;
1202 }
1203 u2 new_num = k_new_method->method_idnum();
1204 Method* idnum_owner = scratch_class->method_with_idnum(num);
1205 if (idnum_owner != nullptr) {
1206 // There is already a method assigned this idnum -- switch them
1207 // Take current and original idnum from the new_method
1208 idnum_owner->set_method_idnum(new_num);
1209 idnum_owner->set_orig_method_idnum(k_new_method->orig_method_idnum());
1210 }
1211 k_new_method->set_method_idnum(num);
1212 k_new_method->set_orig_method_idnum(num);
1213 if (thread->has_pending_exception()) {
1214 return JVMTI_ERROR_OUT_OF_MEMORY;
1215 }
1216 }
1217 log_trace(redefine, class, normalize)
1218 ("Method added: new: %s [%d]", k_new_method->name_and_sig_as_C_string(), ni);
1219 ++ni; // advance to next new method
1220 break;
1221 case deleted:
1222 // method deleted, see if it is OK
1223 if (!can_add_or_delete(k_old_method)) {
1224 log_info(redefine, class, normalize)
1225 ("redefined class %s methods error: deleted method %s [%d]",
1226 the_class->external_name(), k_old_method->name_and_sig_as_C_string(), oi);
1227 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_METHOD_DELETED;
1228 }
1229 log_trace(redefine, class, normalize)
1230 ("Method deleted: old: %s [%d]", k_old_method->name_and_sig_as_C_string(), oi);
1231 ++oi; // advance to next old method
1232 break;
1233 default:
1234 ShouldNotReachHere();
1235 }
1236 }
1237
1238 return JVMTI_ERROR_NONE;
1239 }
1240
1241
1242 // Find new constant pool index value for old constant pool index value
1243 // by searching the index map. Returns zero (0) if there is no mapped
1244 // value for the old constant pool index.
1245 u2 VM_RedefineClasses::find_new_index(int old_index) {
1246 if (_index_map_count == 0) {
1247 // map is empty so nothing can be found
1248 return 0;
1249 }
1250
1251 if (old_index < 1 || old_index >= _index_map_p->length()) {
1252 // The old_index is out of range so it is not mapped. This should
1253 // not happen in regular constant pool merging use, but it can
1254 // happen if a corrupt annotation is processed.
1255 return 0;
1256 }
1257
1258 int value = _index_map_p->at(old_index);
1259 if (value == -1) {
1260 // the old_index is not mapped
1261 return 0;
1262 }
1263
1264 // constant pool indices are u2, unless the merged constant pool overflows which
1265 // we don't check for.
1266 return checked_cast<u2>(value);
1267 } // end find_new_index()
1268
1269
1270 // Find new bootstrap specifier index value for old bootstrap specifier index
1271 // value by searching the index map. Returns unused index (-1) if there is
1272 // no mapped value for the old bootstrap specifier index.
1273 int VM_RedefineClasses::find_new_bsm_index(int old_index) {
1274 if (_bsm_index_map_count == 0) {
1275 // map is empty so nothing can be found
1276 return -1;
1277 }
1278
1279 if (old_index == -1 || old_index >= _bsm_index_map_p->length()) {
1280 // The old_index is out of range so it is not mapped.
1281 // This should not happen in regular constant pool merging use.
1282 return -1;
1283 }
1284
1285 int value = _bsm_index_map_p->at(old_index);
1286 if (value == -1) {
1287 // the old_index is not mapped
1288 return -1;
1289 }
1290
1291 return value;
1292 } // end find_new_bsm_index()
1293
1294
1295 // The bug 6214132 caused the verification to fail.
1296 // 1. What's done in RedefineClasses() before verification:
1297 // a) A reference to the class being redefined (_the_class) and a
1298 // reference to new version of the class (_scratch_class) are
1299 // saved here for use during the bytecode verification phase of
1300 // RedefineClasses.
1301 // b) The _java_mirror field from _the_class is copied to the
1302 // _java_mirror field in _scratch_class. This means that a jclass
1303 // returned for _the_class or _scratch_class will refer to the
1304 // same Java mirror. The verifier will see the "one true mirror"
1305 // for the class being verified.
1306 // 2. See comments in JvmtiThreadState for what is done during verification.
1307
1308 class RedefineVerifyMark : public StackObj {
1309 private:
1310 JvmtiThreadState* _state;
1311 InstanceKlass* _scratch_class;
1312 OopHandle _scratch_mirror;
1313
1314 public:
1315
1316 RedefineVerifyMark(InstanceKlass* the_class, InstanceKlass* scratch_class,
1317 JvmtiThreadState* state) : _state(state), _scratch_class(scratch_class)
1318 {
1319 _state->set_class_versions_map(the_class, scratch_class);
1320 _scratch_mirror = the_class->java_mirror_handle(); // this is a copy that is swapped
1321 _scratch_class->swap_java_mirror_handle(_scratch_mirror);
1322 }
1323
1324 ~RedefineVerifyMark() {
1325 // Restore the scratch class's mirror, so when scratch_class is removed
1326 // the correct mirror pointing to it can be cleared.
1327 _scratch_class->swap_java_mirror_handle(_scratch_mirror);
1328 _state->clear_class_versions_map();
1329 }
1330 };
1331
1332
1333 jvmtiError VM_RedefineClasses::load_new_class_versions() {
1334
1335 // For consistency allocate memory using os::malloc wrapper.
1336 _scratch_classes = (InstanceKlass**)
1337 os::malloc(sizeof(InstanceKlass*) * _class_count, mtClass);
1338 if (_scratch_classes == nullptr) {
1339 return JVMTI_ERROR_OUT_OF_MEMORY;
1340 }
1341 // Zero initialize the _scratch_classes array.
1342 for (int i = 0; i < _class_count; i++) {
1343 _scratch_classes[i] = nullptr;
1344 }
1345
1346 JavaThread* current = JavaThread::current();
1347 ResourceMark rm(current);
1348
1349 JvmtiThreadState *state = JvmtiThreadState::state_for(current);
1350 // state can only be null if the current thread is exiting which
1351 // should not happen since we're trying to do a RedefineClasses
1352 guarantee(state != nullptr, "exiting thread calling load_new_class_versions");
1353 for (int i = 0; i < _class_count; i++) {
1354 // Create HandleMark so that any handles created while loading new class
1355 // versions are deleted. Constant pools are deallocated while merging
1356 // constant pools
1357 HandleMark hm(current);
1358 InstanceKlass* the_class = get_ik(_class_defs[i].klass);
1359 physical_memory_size_type avail_mem = 0;
1360 // Return value ignored - defaulting to 0 on failure.
1361 (void)os::available_memory(avail_mem);
1362 log_debug(redefine, class, load)
1363 ("loading name=%s kind=%d (avail_mem=" PHYS_MEM_TYPE_FORMAT "K)",
1364 the_class->external_name(), _class_load_kind, avail_mem >> 10);
1365
1366 ClassFileStream st((u1*)_class_defs[i].class_bytes,
1367 _class_defs[i].class_byte_count,
1368 "__VM_RedefineClasses__");
1369
1370 // Set redefined class handle in JvmtiThreadState class.
1371 // This redefined class is sent to agent event handler for class file
1372 // load hook event.
1373 state->set_class_being_redefined(the_class, _class_load_kind);
1374
1375 JavaThread* THREAD = current; // For exception macros.
1376 ExceptionMark em(THREAD);
1377 Handle protection_domain(THREAD, the_class->protection_domain());
1378 ClassLoadInfo cl_info(protection_domain);
1379 // Parse and create a class from the bytes, but this class isn't added
1380 // to the dictionary, so do not call resolve_from_stream.
1381 InstanceKlass* scratch_class = KlassFactory::create_from_stream(&st,
1382 the_class->name(),
1383 the_class->class_loader_data(),
1384 cl_info,
1385 THREAD);
1386
1387 // Clear class_being_redefined just to be sure.
1388 state->clear_class_being_redefined();
1389
1390 // TODO: if this is retransform, and nothing changed we can skip it
1391
1392 // Need to clean up allocated InstanceKlass if there's an error so assign
1393 // the result here. Caller deallocates all the scratch classes in case of
1394 // an error.
1395 _scratch_classes[i] = scratch_class;
1396
1397 if (HAS_PENDING_EXCEPTION) {
1398 Symbol* ex_name = PENDING_EXCEPTION->klass()->name();
1399 log_info(redefine, class, load, exceptions)("create_from_stream exception: '%s'", ex_name->as_C_string());
1400 CLEAR_PENDING_EXCEPTION;
1401
1402 if (ex_name == vmSymbols::java_lang_UnsupportedClassVersionError()) {
1403 return JVMTI_ERROR_UNSUPPORTED_VERSION;
1404 } else if (ex_name == vmSymbols::java_lang_ClassFormatError()) {
1405 return JVMTI_ERROR_INVALID_CLASS_FORMAT;
1406 } else if (ex_name == vmSymbols::java_lang_ClassCircularityError()) {
1407 return JVMTI_ERROR_CIRCULAR_CLASS_DEFINITION;
1408 } else if (ex_name == vmSymbols::java_lang_NoClassDefFoundError()) {
1409 // The message will be "XXX (wrong name: YYY)"
1410 return JVMTI_ERROR_NAMES_DONT_MATCH;
1411 } else if (ex_name == vmSymbols::java_lang_OutOfMemoryError()) {
1412 return JVMTI_ERROR_OUT_OF_MEMORY;
1413 } else { // Just in case more exceptions can be thrown..
1414 return JVMTI_ERROR_FAILS_VERIFICATION;
1415 }
1416 }
1417
1418 // Ensure class is linked before redefine
1419 if (!the_class->is_linked()) {
1420 the_class->link_class(THREAD);
1421 if (HAS_PENDING_EXCEPTION) {
1422 Symbol* ex_name = PENDING_EXCEPTION->klass()->name();
1423 oop message = java_lang_Throwable::message(PENDING_EXCEPTION);
1424 if (message != nullptr) {
1425 char* ex_msg = java_lang_String::as_utf8_string(message);
1426 log_info(redefine, class, load, exceptions)("link_class exception: '%s %s'",
1427 ex_name->as_C_string(), ex_msg);
1428 } else {
1429 log_info(redefine, class, load, exceptions)("link_class exception: '%s'",
1430 ex_name->as_C_string());
1431 }
1432 CLEAR_PENDING_EXCEPTION;
1433 if (ex_name == vmSymbols::java_lang_OutOfMemoryError()) {
1434 return JVMTI_ERROR_OUT_OF_MEMORY;
1435 } else if (ex_name == vmSymbols::java_lang_NoClassDefFoundError()) {
1436 return JVMTI_ERROR_INVALID_CLASS;
1437 } else {
1438 return JVMTI_ERROR_INTERNAL;
1439 }
1440 }
1441 }
1442
1443 // Do the validity checks in compare_and_normalize_class_versions()
1444 // before verifying the byte codes. By doing these checks first, we
1445 // limit the number of functions that require redirection from
1446 // the_class to scratch_class. In particular, we don't have to
1447 // modify JNI GetSuperclass() and thus won't change its performance.
1448 jvmtiError res = compare_and_normalize_class_versions(the_class,
1449 scratch_class);
1450 if (res != JVMTI_ERROR_NONE) {
1451 return res;
1452 }
1453
1454 // verify what the caller passed us
1455 {
1456 // The bug 6214132 caused the verification to fail.
1457 // Information about the_class and scratch_class is temporarily
1458 // recorded into jvmtiThreadState. This data is used to redirect
1459 // the_class to scratch_class in the JVM_* functions called by the
1460 // verifier. Please, refer to jvmtiThreadState.hpp for the detailed
1461 // description.
1462 RedefineVerifyMark rvm(the_class, scratch_class, state);
1463 Verifier::verify(scratch_class, true, THREAD);
1464 }
1465
1466 if (HAS_PENDING_EXCEPTION) {
1467 Symbol* ex_name = PENDING_EXCEPTION->klass()->name();
1468 log_info(redefine, class, load, exceptions)("verify_byte_codes exception: '%s'", ex_name->as_C_string());
1469 CLEAR_PENDING_EXCEPTION;
1470 if (ex_name == vmSymbols::java_lang_OutOfMemoryError()) {
1471 return JVMTI_ERROR_OUT_OF_MEMORY;
1472 } else {
1473 // tell the caller the bytecodes are bad
1474 return JVMTI_ERROR_FAILS_VERIFICATION;
1475 }
1476 }
1477
1478 res = merge_cp_and_rewrite(the_class, scratch_class, THREAD);
1479 if (HAS_PENDING_EXCEPTION) {
1480 Symbol* ex_name = PENDING_EXCEPTION->klass()->name();
1481 log_info(redefine, class, load, exceptions)("merge_cp_and_rewrite exception: '%s'", ex_name->as_C_string());
1482 CLEAR_PENDING_EXCEPTION;
1483 if (ex_name == vmSymbols::java_lang_OutOfMemoryError()) {
1484 return JVMTI_ERROR_OUT_OF_MEMORY;
1485 } else {
1486 return JVMTI_ERROR_INTERNAL;
1487 }
1488 } else if (res != JVMTI_ERROR_NONE) {
1489 return res;
1490 }
1491
1492 #ifdef ASSERT
1493 {
1494 // verify what we have done during constant pool merging
1495 {
1496 RedefineVerifyMark rvm(the_class, scratch_class, state);
1497 Verifier::verify(scratch_class, true, THREAD);
1498 }
1499
1500 if (HAS_PENDING_EXCEPTION) {
1501 Symbol* ex_name = PENDING_EXCEPTION->klass()->name();
1502 log_info(redefine, class, load, exceptions)
1503 ("verify_byte_codes post merge-CP exception: '%s'", ex_name->as_C_string());
1504 CLEAR_PENDING_EXCEPTION;
1505 if (ex_name == vmSymbols::java_lang_OutOfMemoryError()) {
1506 return JVMTI_ERROR_OUT_OF_MEMORY;
1507 } else {
1508 // tell the caller that constant pool merging screwed up
1509 return JVMTI_ERROR_INTERNAL;
1510 }
1511 }
1512 }
1513 #endif // ASSERT
1514
1515 Rewriter::rewrite(scratch_class, THREAD);
1516 if (!HAS_PENDING_EXCEPTION) {
1517 scratch_class->link_methods(THREAD);
1518 }
1519 if (HAS_PENDING_EXCEPTION) {
1520 Symbol* ex_name = PENDING_EXCEPTION->klass()->name();
1521 log_info(redefine, class, load, exceptions)
1522 ("Rewriter::rewrite or link_methods exception: '%s'", ex_name->as_C_string());
1523 CLEAR_PENDING_EXCEPTION;
1524 if (ex_name == vmSymbols::java_lang_OutOfMemoryError()) {
1525 return JVMTI_ERROR_OUT_OF_MEMORY;
1526 } else {
1527 return JVMTI_ERROR_INTERNAL;
1528 }
1529 }
1530 // Return value ignored - defaulting to 0 on failure.
1531 (void)os::available_memory(avail_mem);
1532 log_debug(redefine, class, load)
1533 ("loaded name=%s (avail_mem=" PHYS_MEM_TYPE_FORMAT "K)", the_class->external_name(), avail_mem >> 10);
1534 }
1535
1536 return JVMTI_ERROR_NONE;
1537 }
1538
1539
1540 // Map old_index to new_index as needed. scratch_cp is only needed
1541 // for log calls.
1542 void VM_RedefineClasses::map_index(const constantPoolHandle& scratch_cp,
1543 int old_index, int new_index) {
1544 if (find_new_index(old_index) != 0) {
1545 // old_index is already mapped
1546 return;
1547 }
1548
1549 if (old_index == new_index) {
1550 // no mapping is needed
1551 return;
1552 }
1553
1554 _index_map_p->at_put(old_index, new_index);
1555 _index_map_count++;
1556
1557 log_trace(redefine, class, constantpool)
1558 ("mapped tag %d at index %d to %d", scratch_cp->tag_at(old_index).value(), old_index, new_index);
1559 } // end map_index()
1560
1561
1562 // Map old_index to new_index as needed.
1563 void VM_RedefineClasses::map_bsm_index(int old_index, int new_index) {
1564 if (old_index == new_index) {
1565 // no mapping is needed
1566 return;
1567 }
1568 _bsm_index_map_p->at_put(old_index, new_index);
1569 _bsm_index_map_count++;
1570 log_trace(redefine, class, constantpool)("mapped bootstrap specifier at index %d to %d", old_index, new_index);
1571 } // end map_bsm_index()
1572
1573
1574 // Merge old_cp and scratch_cp and return the results of the merge via
1575 // merge_cp_p. The number of entries in merge_cp_p is returned via
1576 // merge_cp_length_p. The entries in old_cp occupy the same locations
1577 // in merge_cp_p. Also creates a map of indices from entries in
1578 // scratch_cp to the corresponding entry in merge_cp_p. Index map
1579 // entries are only created for entries in scratch_cp that occupy a
1580 // different location in merged_cp_p.
1581 bool VM_RedefineClasses::merge_constant_pools(const constantPoolHandle& old_cp,
1582 const constantPoolHandle& scratch_cp, constantPoolHandle& merge_cp_p,
1583 int& merge_cp_length_p, TRAPS) {
1584
1585 // Worst case we need old_cp->length() + scratch_cp()->length(),
1586 // but the caller might be smart so make sure we have at least
1587 // the minimum.
1588 if (merge_cp_p->length() < old_cp->length()) {
1589 assert(false, "merge area too small");
1590 return false; // robustness
1591 }
1592
1593 log_info(redefine, class, constantpool)("old_cp_len=%d, scratch_cp_len=%d", old_cp->length(), scratch_cp->length());
1594
1595 {
1596 // Pass 0:
1597 // The old_cp is copied to *merge_cp_p; this means that any code
1598 // using old_cp does not have to change. This work looks like a
1599 // perfect fit for ConstantPool*::copy_cp_to(), but we need to
1600 // handle one special case:
1601 // - revert JVM_CONSTANT_Class to JVM_CONSTANT_UnresolvedClass
1602 // This will make verification happy.
1603
1604 int old_i; // index into old_cp
1605
1606 // index zero (0) is not used in constantPools
1607 for (old_i = 1; old_i < old_cp->length(); old_i++) {
1608 // leave debugging crumb
1609 jbyte old_tag = old_cp->tag_at(old_i).value();
1610 switch (old_tag) {
1611 case JVM_CONSTANT_Class:
1612 case JVM_CONSTANT_UnresolvedClass:
1613 // revert the copy to JVM_CONSTANT_UnresolvedClass
1614 // May be resolving while calling this so do the same for
1615 // JVM_CONSTANT_UnresolvedClass (klass_name_at() deals with transition)
1616 merge_cp_p->temp_unresolved_klass_at_put(old_i,
1617 old_cp->klass_name_index_at(old_i));
1618 break;
1619
1620 case JVM_CONSTANT_Double:
1621 case JVM_CONSTANT_Long:
1622 // just copy the entry to merge_cp_p, but double and long take
1623 // two constant pool entries
1624 ConstantPool::copy_entry_to(old_cp, old_i, merge_cp_p, old_i);
1625 old_i++;
1626 break;
1627
1628 default:
1629 // just copy the entry to merge_cp_p
1630 ConstantPool::copy_entry_to(old_cp, old_i, merge_cp_p, old_i);
1631 break;
1632 }
1633 } // end for each old_cp entry
1634
1635 ConstantPool::copy_bsm_entries(old_cp, merge_cp_p, CHECK_false);
1636 _bsmae_iter = merge_cp_p->start_extension(scratch_cp, CHECK_false);
1637
1638 // We don't need to sanity check that *merge_cp_length_p is within
1639 // *merge_cp_p bounds since we have the minimum on-entry check above.
1640 merge_cp_length_p = old_i;
1641 }
1642
1643 // merge_cp_len should be the same as old_cp->length() at this point
1644 // so this trace message is really a "warm-and-breathing" message.
1645 log_debug(redefine, class, constantpool)("after pass 0: merge_cp_len=%d", merge_cp_length_p);
1646
1647 int scratch_i; // index into scratch_cp
1648 {
1649 // Pass 1a:
1650 // Compare scratch_cp entries to the old_cp entries that we have
1651 // already copied to *merge_cp_p. In this pass, we are eliminating
1652 // exact duplicates (matching entry at same index) so we only
1653 // compare entries in the common indice range.
1654 int increment = 1;
1655 int pass1a_length = MIN2(old_cp->length(), scratch_cp->length());
1656 for (scratch_i = 1; scratch_i < pass1a_length; scratch_i += increment) {
1657 switch (scratch_cp->tag_at(scratch_i).value()) {
1658 case JVM_CONSTANT_Double:
1659 case JVM_CONSTANT_Long:
1660 // double and long take two constant pool entries
1661 increment = 2;
1662 break;
1663
1664 default:
1665 increment = 1;
1666 break;
1667 }
1668
1669 bool match = scratch_cp->compare_entry_to(scratch_i, merge_cp_p, scratch_i);
1670 if (match) {
1671 // found a match at the same index so nothing more to do
1672 continue;
1673 }
1674
1675 int found_i = scratch_cp->find_matching_entry(scratch_i, merge_cp_p);
1676 if (found_i != 0) {
1677 guarantee(found_i != scratch_i,
1678 "compare_entry_to() and find_matching_entry() do not agree");
1679
1680 // Found a matching entry somewhere else in *merge_cp_p so
1681 // just need a mapping entry.
1682 map_index(scratch_cp, scratch_i, found_i);
1683 continue;
1684 }
1685
1686 // No match found so we have to append this entry and any unique
1687 // referenced entries to merge_cp_p.
1688 append_entry(scratch_cp, scratch_i, &merge_cp_p, &merge_cp_length_p);
1689 }
1690 }
1691
1692 log_debug(redefine, class, constantpool)
1693 ("after pass 1a: merge_cp_len=%d, scratch_i=%d, index_map_len=%d",
1694 merge_cp_length_p, scratch_i, _index_map_count);
1695
1696 if (scratch_i < scratch_cp->length()) {
1697 // Pass 1b:
1698 // old_cp is smaller than scratch_cp so there are entries in
1699 // scratch_cp that we have not yet processed. We take care of
1700 // those now.
1701 int increment = 1;
1702 for (; scratch_i < scratch_cp->length(); scratch_i += increment) {
1703 switch (scratch_cp->tag_at(scratch_i).value()) {
1704 case JVM_CONSTANT_Double:
1705 case JVM_CONSTANT_Long:
1706 // double and long take two constant pool entries
1707 increment = 2;
1708 break;
1709
1710 default:
1711 increment = 1;
1712 break;
1713 }
1714
1715 int found_i =
1716 scratch_cp->find_matching_entry(scratch_i, merge_cp_p);
1717 if (found_i != 0) {
1718 // Found a matching entry somewhere else in merge_cp_p so
1719 // just need a mapping entry.
1720 map_index(scratch_cp, scratch_i, found_i);
1721 continue;
1722 }
1723
1724 // No match found so we have to append this entry and any unique
1725 // referenced entries to merge_cp_p.
1726 append_entry(scratch_cp, scratch_i, &merge_cp_p, &merge_cp_length_p);
1727 }
1728
1729 log_debug(redefine, class, constantpool)
1730 ("after pass 1b: merge_cp_len=%d, scratch_i=%d, index_map_len=%d",
1731 merge_cp_length_p, scratch_i, _index_map_count);
1732 }
1733 finalize_bsm_entries_merge(merge_cp_p, CHECK_false);
1734
1735 return true;
1736 } // end merge_constant_pools()
1737
1738
1739 // Scoped object to clean up the constant pool(s) created for merging
1740 class MergeCPCleaner {
1741 ClassLoaderData* _loader_data;
1742 ConstantPool* _cp;
1743 ConstantPool* _scratch_cp;
1744 public:
1745 MergeCPCleaner(ClassLoaderData* loader_data, ConstantPool* merge_cp) :
1746 _loader_data(loader_data), _cp(merge_cp), _scratch_cp(nullptr) {}
1747 ~MergeCPCleaner() {
1748 _loader_data->add_to_deallocate_list(_cp);
1749 if (_scratch_cp != nullptr) {
1750 _loader_data->add_to_deallocate_list(_scratch_cp);
1751 }
1752 }
1753 void add_scratch_cp(ConstantPool* scratch_cp) { _scratch_cp = scratch_cp; }
1754 };
1755
1756 // Merge constant pools between the_class and scratch_class and
1757 // potentially rewrite bytecodes in scratch_class to use the merged
1758 // constant pool.
1759 jvmtiError VM_RedefineClasses::merge_cp_and_rewrite(
1760 InstanceKlass* the_class, InstanceKlass* scratch_class,
1761 TRAPS) {
1762 // worst case merged constant pool length is old and new combined
1763 int merge_cp_length = the_class->constants()->length()
1764 + scratch_class->constants()->length();
1765
1766 // Constant pools are not easily reused so we allocate a new one
1767 // each time.
1768 // merge_cp is created unsafe for concurrent GC processing. It
1769 // should be marked safe before discarding it. Even though
1770 // garbage, if it crosses a card boundary, it may be scanned
1771 // in order to find the start of the first complete object on the card.
1772 ClassLoaderData* loader_data = the_class->class_loader_data();
1773 ConstantPool* merge_cp_oop =
1774 ConstantPool::allocate(loader_data,
1775 merge_cp_length,
1776 CHECK_(JVMTI_ERROR_OUT_OF_MEMORY));
1777 MergeCPCleaner cp_cleaner(loader_data, merge_cp_oop);
1778
1779 HandleMark hm(THREAD); // make sure handles are cleared before
1780 // MergeCPCleaner clears out merge_cp_oop
1781 constantPoolHandle merge_cp(THREAD, merge_cp_oop);
1782
1783 // Get constants() from the old class because it could have been rewritten
1784 // while we were at a safepoint allocating a new constant pool.
1785 constantPoolHandle old_cp(THREAD, the_class->constants());
1786 constantPoolHandle scratch_cp(THREAD, scratch_class->constants());
1787
1788 // If the length changed, the class was redefined out from under us. Return
1789 // an error.
1790 if (merge_cp_length != the_class->constants()->length()
1791 + scratch_class->constants()->length()) {
1792 return JVMTI_ERROR_INTERNAL;
1793 }
1794
1795 // Update the version number of the constant pools (may keep scratch_cp)
1796 merge_cp->increment_and_save_version(old_cp->version());
1797 scratch_cp->increment_and_save_version(old_cp->version());
1798
1799 ResourceMark rm(THREAD);
1800 _index_map_count = 0;
1801 _index_map_p = new intArray(scratch_cp->length(), scratch_cp->length(), -1);
1802
1803 _bsm_index_map_count = 0;
1804 int bsm_data_len = scratch_cp->bsm_entries().array_length();
1805 _bsm_index_map_p = new intArray(bsm_data_len, bsm_data_len, -1);
1806
1807 // reference to the cp holder is needed for reallocating the BSM attribute
1808 merge_cp->set_pool_holder(scratch_class);
1809 bool result = merge_constant_pools(old_cp, scratch_cp, merge_cp,
1810 merge_cp_length, THREAD);
1811 merge_cp->set_pool_holder(nullptr);
1812
1813 if (!result) {
1814 // The merge can fail due to memory allocation failure or due
1815 // to robustness checks.
1816 return JVMTI_ERROR_INTERNAL;
1817 }
1818
1819 // ensure merged constant pool size does not overflow u2
1820 if (merge_cp_length > 0xFFFF) {
1821 log_warning(redefine, class, constantpool)("Merged constant pool overflow: %d entries", merge_cp_length);
1822 return JVMTI_ERROR_INTERNAL;
1823 }
1824
1825 // Set dynamic constants attribute from the original CP.
1826 if (old_cp->has_dynamic_constant()) {
1827 scratch_cp->set_has_dynamic_constant();
1828 }
1829
1830 log_info(redefine, class, constantpool)("merge_cp_len=%d, index_map_len=%d", merge_cp_length, _index_map_count);
1831
1832 if (_index_map_count == 0) {
1833 // there is nothing to map between the new and merged constant pools
1834
1835 // Copy attributes from scratch_cp to merge_cp
1836 merge_cp->copy_fields(scratch_cp());
1837
1838 if (old_cp->length() == scratch_cp->length()) {
1839 // The old and new constant pools are the same length and the
1840 // index map is empty. This means that the three constant pools
1841 // are equivalent (but not the same). Unfortunately, the new
1842 // constant pool has not gone through link resolution nor have
1843 // the new class bytecodes gone through constant pool cache
1844 // rewriting so we can't use the old constant pool with the new
1845 // class.
1846
1847 // toss the merged constant pool at return
1848 } else if (old_cp->length() < scratch_cp->length()) {
1849 // The old constant pool has fewer entries than the new constant
1850 // pool and the index map is empty. This means the new constant
1851 // pool is a superset of the old constant pool. However, the old
1852 // class bytecodes have already gone through constant pool cache
1853 // rewriting so we can't use the new constant pool with the old
1854 // class.
1855
1856 // toss the merged constant pool at return
1857 } else {
1858 // The old constant pool has more entries than the new constant
1859 // pool and the index map is empty. This means that both the old
1860 // and merged constant pools are supersets of the new constant
1861 // pool.
1862
1863 // Replace the new constant pool with a shrunken copy of the
1864 // merged constant pool
1865 set_new_constant_pool(loader_data, scratch_class, merge_cp, merge_cp_length,
1866 CHECK_(JVMTI_ERROR_OUT_OF_MEMORY));
1867 // The new constant pool replaces scratch_cp so have cleaner clean it up.
1868 // It can't be cleaned up while there are handles to it.
1869 cp_cleaner.add_scratch_cp(scratch_cp());
1870 }
1871 } else {
1872 if (log_is_enabled(Trace, redefine, class, constantpool)) {
1873 // don't want to loop unless we are tracing
1874 int count = 0;
1875 for (int i = 1; i < _index_map_p->length(); i++) {
1876 int value = _index_map_p->at(i);
1877
1878 if (value != -1) {
1879 log_trace(redefine, class, constantpool)("index_map[%d]: old=%d new=%d", count, i, value);
1880 count++;
1881 }
1882 }
1883 }
1884
1885 // We have entries mapped between the new and merged constant pools
1886 // so we have to rewrite some constant pool references.
1887 if (!rewrite_cp_refs(scratch_class)) {
1888 return JVMTI_ERROR_INTERNAL;
1889 }
1890
1891 // Copy attributes from scratch_cp to merge_cp (should be done after rewrite_cp_refs())
1892 merge_cp->copy_fields(scratch_cp());
1893
1894 // Replace the new constant pool with a shrunken copy of the
1895 // merged constant pool so now the rewritten bytecodes have
1896 // valid references; the previous new constant pool will get
1897 // GCed.
1898 set_new_constant_pool(loader_data, scratch_class, merge_cp, merge_cp_length,
1899 CHECK_(JVMTI_ERROR_OUT_OF_MEMORY));
1900 // The new constant pool replaces scratch_cp so have cleaner clean it up.
1901 // It can't be cleaned up while there are handles to it.
1902 cp_cleaner.add_scratch_cp(scratch_cp());
1903 }
1904
1905 return JVMTI_ERROR_NONE;
1906 } // end merge_cp_and_rewrite()
1907
1908
1909 // Rewrite constant pool references in klass scratch_class.
1910 bool VM_RedefineClasses::rewrite_cp_refs(InstanceKlass* scratch_class) {
1911
1912 // rewrite constant pool references in the nest attributes:
1913 if (!rewrite_cp_refs_in_nest_attributes(scratch_class)) {
1914 // propagate failure back to caller
1915 return false;
1916 }
1917
1918 // rewrite constant pool references in the Record attribute:
1919 if (!rewrite_cp_refs_in_record_attribute(scratch_class)) {
1920 // propagate failure back to caller
1921 return false;
1922 }
1923
1924 // rewrite constant pool references in the PermittedSubclasses attribute:
1925 if (!rewrite_cp_refs_in_permitted_subclasses_attribute(scratch_class)) {
1926 // propagate failure back to caller
1927 return false;
1928 }
1929
1930 // rewrite constant pool references in the LoadableDescriptors attribute:
1931 if (!rewrite_cp_refs_in_loadable_descriptors_attribute(scratch_class)) {
1932 // propagate failure back to caller
1933 return false;
1934 }
1935
1936 // rewrite constant pool references in the methods:
1937 if (!rewrite_cp_refs_in_methods(scratch_class)) {
1938 // propagate failure back to caller
1939 return false;
1940 }
1941
1942 // rewrite constant pool references in the class_annotations:
1943 if (!rewrite_cp_refs_in_class_annotations(scratch_class)) {
1944 // propagate failure back to caller
1945 return false;
1946 }
1947
1948 // rewrite constant pool references in the fields_annotations:
1949 if (!rewrite_cp_refs_in_fields_annotations(scratch_class)) {
1950 // propagate failure back to caller
1951 return false;
1952 }
1953
1954 // rewrite constant pool references in the methods_annotations:
1955 if (!rewrite_cp_refs_in_methods_annotations(scratch_class)) {
1956 // propagate failure back to caller
1957 return false;
1958 }
1959
1960 // rewrite constant pool references in the methods_parameter_annotations:
1961 if (!rewrite_cp_refs_in_methods_parameter_annotations(scratch_class)) {
1962 // propagate failure back to caller
1963 return false;
1964 }
1965
1966 // rewrite constant pool references in the methods_default_annotations:
1967 if (!rewrite_cp_refs_in_methods_default_annotations(scratch_class)) {
1968 // propagate failure back to caller
1969 return false;
1970 }
1971
1972 // rewrite constant pool references in the class_type_annotations:
1973 if (!rewrite_cp_refs_in_class_type_annotations(scratch_class)) {
1974 // propagate failure back to caller
1975 return false;
1976 }
1977
1978 // rewrite constant pool references in the fields_type_annotations:
1979 if (!rewrite_cp_refs_in_fields_type_annotations(scratch_class)) {
1980 // propagate failure back to caller
1981 return false;
1982 }
1983
1984 // rewrite constant pool references in the methods_type_annotations:
1985 if (!rewrite_cp_refs_in_methods_type_annotations(scratch_class)) {
1986 // propagate failure back to caller
1987 return false;
1988 }
1989
1990 // There can be type annotations in the Code part of a method_info attribute.
1991 // These annotations are not accessible, even by reflection.
1992 // Currently they are not even parsed by the ClassFileParser.
1993 // If runtime access is added they will also need to be rewritten.
1994
1995 // rewrite source file name index:
1996 u2 source_file_name_idx = scratch_class->source_file_name_index();
1997 if (source_file_name_idx != 0) {
1998 u2 new_source_file_name_idx = find_new_index(source_file_name_idx);
1999 if (new_source_file_name_idx != 0) {
2000 scratch_class->set_source_file_name_index(new_source_file_name_idx);
2001 }
2002 }
2003
2004 // rewrite class generic signature index:
2005 u2 generic_signature_index = scratch_class->generic_signature_index();
2006 if (generic_signature_index != 0) {
2007 u2 new_generic_signature_index = find_new_index(generic_signature_index);
2008 if (new_generic_signature_index != 0) {
2009 scratch_class->set_generic_signature_index(new_generic_signature_index);
2010 }
2011 }
2012
2013 return true;
2014 } // end rewrite_cp_refs()
2015
2016 // Rewrite constant pool references in the NestHost and NestMembers attributes.
2017 bool VM_RedefineClasses::rewrite_cp_refs_in_nest_attributes(
2018 InstanceKlass* scratch_class) {
2019
2020 u2 cp_index = scratch_class->nest_host_index();
2021 if (cp_index != 0) {
2022 scratch_class->set_nest_host_index(find_new_index(cp_index));
2023 }
2024 Array<u2>* nest_members = scratch_class->nest_members();
2025 for (int i = 0; i < nest_members->length(); i++) {
2026 u2 cp_index = nest_members->at(i);
2027 nest_members->at_put(i, find_new_index(cp_index));
2028 }
2029 return true;
2030 }
2031
2032 // Rewrite constant pool references in the Record attribute.
2033 bool VM_RedefineClasses::rewrite_cp_refs_in_record_attribute(InstanceKlass* scratch_class) {
2034 Array<RecordComponent*>* components = scratch_class->record_components();
2035 if (components != nullptr) {
2036 for (int i = 0; i < components->length(); i++) {
2037 RecordComponent* component = components->at(i);
2038 u2 cp_index = component->name_index();
2039 component->set_name_index(find_new_index(cp_index));
2040 cp_index = component->descriptor_index();
2041 component->set_descriptor_index(find_new_index(cp_index));
2042 cp_index = component->generic_signature_index();
2043 if (cp_index != 0) {
2044 component->set_generic_signature_index(find_new_index(cp_index));
2045 }
2046
2047 AnnotationArray* annotations = component->annotations();
2048 if (annotations != nullptr && annotations->length() != 0) {
2049 int byte_i = 0; // byte index into annotations
2050 if (!rewrite_cp_refs_in_annotations_typeArray(annotations, byte_i)) {
2051 log_debug(redefine, class, annotation)("bad record_component_annotations at %d", i);
2052 // propagate failure back to caller
2053 return false;
2054 }
2055 }
2056
2057 AnnotationArray* type_annotations = component->type_annotations();
2058 if (type_annotations != nullptr && type_annotations->length() != 0) {
2059 int byte_i = 0; // byte index into annotations
2060 if (!rewrite_cp_refs_in_type_annotations_typeArray(type_annotations, byte_i, "record_info")) {
2061 log_debug(redefine, class, annotation)("bad record_component_type_annotations at %d", i);
2062 // propagate failure back to caller
2063 return false;
2064 }
2065 }
2066 }
2067 }
2068 return true;
2069 }
2070
2071 // Rewrite constant pool references in the PermittedSubclasses attribute.
2072 bool VM_RedefineClasses::rewrite_cp_refs_in_permitted_subclasses_attribute(
2073 InstanceKlass* scratch_class) {
2074
2075 Array<u2>* permitted_subclasses = scratch_class->permitted_subclasses();
2076 assert(permitted_subclasses != nullptr, "unexpected null permitted_subclasses");
2077 for (int i = 0; i < permitted_subclasses->length(); i++) {
2078 u2 cp_index = permitted_subclasses->at(i);
2079 permitted_subclasses->at_put(i, find_new_index(cp_index));
2080 }
2081 return true;
2082 }
2083
2084 // Rewrite constant pool references in the LoadableDescriptors attribute.
2085 bool VM_RedefineClasses::rewrite_cp_refs_in_loadable_descriptors_attribute(
2086 InstanceKlass* scratch_class) {
2087
2088 Array<u2>* loadable_descriptors = scratch_class->loadable_descriptors();
2089 assert(loadable_descriptors != nullptr, "unexpected null loadable_descriptors");
2090 for (int i = 0; i < loadable_descriptors->length(); i++) {
2091 u2 cp_index = loadable_descriptors->at(i);
2092 loadable_descriptors->at_put(i, find_new_index(cp_index));
2093 }
2094 return true;
2095 }
2096
2097 // Rewrite constant pool references in the methods.
2098 bool VM_RedefineClasses::rewrite_cp_refs_in_methods(InstanceKlass* scratch_class) {
2099
2100 Array<Method*>* methods = scratch_class->methods();
2101
2102 if (methods == nullptr || methods->length() == 0) {
2103 // no methods so nothing to do
2104 return true;
2105 }
2106
2107 JavaThread* THREAD = JavaThread::current(); // For exception macros.
2108 ExceptionMark em(THREAD);
2109
2110 // rewrite constant pool references in the methods:
2111 for (int i = methods->length() - 1; i >= 0; i--) {
2112 methodHandle method(THREAD, methods->at(i));
2113 methodHandle new_method;
2114 rewrite_cp_refs_in_method(method, &new_method, THREAD);
2115 if (!new_method.is_null()) {
2116 // the method has been replaced so save the new method version
2117 // even in the case of an exception. original method is on the
2118 // deallocation list.
2119 methods->at_put(i, new_method());
2120 }
2121 if (HAS_PENDING_EXCEPTION) {
2122 Symbol* ex_name = PENDING_EXCEPTION->klass()->name();
2123 log_info(redefine, class, load, exceptions)("rewrite_cp_refs_in_method exception: '%s'", ex_name->as_C_string());
2124 // Need to clear pending exception here as the super caller sets
2125 // the JVMTI_ERROR_INTERNAL if the returned value is false.
2126 CLEAR_PENDING_EXCEPTION;
2127 return false;
2128 }
2129 }
2130
2131 return true;
2132 }
2133
2134
2135 // Rewrite constant pool references in the specific method. This code
2136 // was adapted from Rewriter::rewrite_method().
2137 void VM_RedefineClasses::rewrite_cp_refs_in_method(methodHandle method,
2138 methodHandle *new_method_p, TRAPS) {
2139
2140 *new_method_p = methodHandle(); // default is no new method
2141
2142 // We cache a pointer to the bytecodes here in code_base. If GC
2143 // moves the Method*, then the bytecodes will also move which
2144 // will likely cause a crash. We create a NoSafepointVerifier
2145 // object to detect whether we pass a possible safepoint in this
2146 // code block.
2147 NoSafepointVerifier nsv;
2148
2149 // Bytecodes and their length
2150 address code_base = method->code_base();
2151 int code_length = method->code_size();
2152
2153 int bc_length;
2154 for (int bci = 0; bci < code_length; bci += bc_length) {
2155 address bcp = code_base + bci;
2156 Bytecodes::Code c = (Bytecodes::Code)(*bcp);
2157
2158 bc_length = Bytecodes::length_for(c);
2159 if (bc_length == 0) {
2160 // More complicated bytecodes report a length of zero so
2161 // we have to try again a slightly different way.
2162 bc_length = Bytecodes::length_at(method(), bcp);
2163 }
2164
2165 assert(bc_length != 0, "impossible bytecode length");
2166
2167 switch (c) {
2168 case Bytecodes::_ldc:
2169 {
2170 u1 cp_index = *(bcp + 1);
2171 u2 new_index = find_new_index(cp_index);
2172
2173 if (StressLdcRewrite && new_index == 0) {
2174 // If we are stressing ldc -> ldc_w rewriting, then we
2175 // always need a new_index value.
2176 new_index = cp_index;
2177 }
2178 if (new_index != 0) {
2179 // the original index is mapped so we have more work to do
2180 if (!StressLdcRewrite && new_index <= max_jubyte) {
2181 // The new value can still use ldc instead of ldc_w
2182 // unless we are trying to stress ldc -> ldc_w rewriting
2183 log_trace(redefine, class, constantpool)
2184 ("%s@" INTPTR_FORMAT " old=%d, new=%d", Bytecodes::name(c), p2i(bcp), cp_index, new_index);
2185 // We checked that new_index fits in a u1 so this cast is safe
2186 *(bcp + 1) = (u1)new_index;
2187 } else {
2188 log_trace(redefine, class, constantpool)
2189 ("%s->ldc_w@" INTPTR_FORMAT " old=%d, new=%d", Bytecodes::name(c), p2i(bcp), cp_index, new_index);
2190 // the new value needs ldc_w instead of ldc
2191 u_char inst_buffer[4]; // max instruction size is 4 bytes
2192 bcp = (address)inst_buffer;
2193 // construct new instruction sequence
2194 *bcp = Bytecodes::_ldc_w;
2195 bcp++;
2196 // Rewriter::rewrite_method() does not rewrite ldc -> ldc_w.
2197 // See comment below for difference between put_Java_u2()
2198 // and put_native_u2().
2199 Bytes::put_Java_u2(bcp, new_index);
2200
2201 Relocator rc(method, nullptr /* no RelocatorListener needed */);
2202 methodHandle m;
2203 {
2204 PauseNoSafepointVerifier pnsv(&nsv);
2205
2206 // ldc is 2 bytes and ldc_w is 3 bytes
2207 m = rc.insert_space_at(bci, 3, inst_buffer, CHECK);
2208 }
2209
2210 // return the new method so that the caller can update
2211 // the containing class
2212 *new_method_p = method = m;
2213 // switch our bytecode processing loop from the old method
2214 // to the new method
2215 code_base = method->code_base();
2216 code_length = method->code_size();
2217 bcp = code_base + bci;
2218 c = (Bytecodes::Code)(*bcp);
2219 bc_length = Bytecodes::length_for(c);
2220 assert(bc_length != 0, "sanity check");
2221 } // end we need ldc_w instead of ldc
2222 } // end if there is a mapped index
2223 } break;
2224
2225 // these bytecodes have a two-byte constant pool index
2226 case Bytecodes::_anewarray : // fall through
2227 case Bytecodes::_checkcast : // fall through
2228 case Bytecodes::_getfield : // fall through
2229 case Bytecodes::_getstatic : // fall through
2230 case Bytecodes::_instanceof : // fall through
2231 case Bytecodes::_invokedynamic : // fall through
2232 case Bytecodes::_invokeinterface: // fall through
2233 case Bytecodes::_invokespecial : // fall through
2234 case Bytecodes::_invokestatic : // fall through
2235 case Bytecodes::_invokevirtual : // fall through
2236 case Bytecodes::_ldc_w : // fall through
2237 case Bytecodes::_ldc2_w : // fall through
2238 case Bytecodes::_multianewarray : // fall through
2239 case Bytecodes::_new : // fall through
2240 case Bytecodes::_putfield : // fall through
2241 case Bytecodes::_putstatic :
2242 {
2243 address p = bcp + 1;
2244 int cp_index = Bytes::get_Java_u2(p);
2245 u2 new_index = find_new_index(cp_index);
2246 if (new_index != 0) {
2247 // the original index is mapped so update w/ new value
2248 log_trace(redefine, class, constantpool)
2249 ("%s@" INTPTR_FORMAT " old=%d, new=%d", Bytecodes::name(c),p2i(bcp), cp_index, new_index);
2250 // Rewriter::rewrite_method() uses put_native_u2() in this
2251 // situation because it is reusing the constant pool index
2252 // location for a native index into the ConstantPoolCache.
2253 // Since we are updating the constant pool index prior to
2254 // verification and ConstantPoolCache initialization, we
2255 // need to keep the new index in Java byte order.
2256 Bytes::put_Java_u2(p, new_index);
2257 }
2258 } break;
2259 default:
2260 break;
2261 }
2262 } // end for each bytecode
2263 } // end rewrite_cp_refs_in_method()
2264
2265
2266 // Rewrite constant pool references in the class_annotations field.
2267 bool VM_RedefineClasses::rewrite_cp_refs_in_class_annotations(InstanceKlass* scratch_class) {
2268
2269 AnnotationArray* class_annotations = scratch_class->class_annotations();
2270 if (class_annotations == nullptr || class_annotations->length() == 0) {
2271 // no class_annotations so nothing to do
2272 return true;
2273 }
2274
2275 log_debug(redefine, class, annotation)("class_annotations length=%d", class_annotations->length());
2276
2277 int byte_i = 0; // byte index into class_annotations
2278 return rewrite_cp_refs_in_annotations_typeArray(class_annotations, byte_i);
2279 }
2280
2281
2282 // Rewrite constant pool references in an annotations typeArray. This
2283 // "structure" is adapted from the RuntimeVisibleAnnotations_attribute
2284 // that is described in section 4.8.15 of the 2nd-edition of the VM spec:
2285 //
2286 // annotations_typeArray {
2287 // u2 num_annotations;
2288 // annotation annotations[num_annotations];
2289 // }
2290 //
2291 bool VM_RedefineClasses::rewrite_cp_refs_in_annotations_typeArray(
2292 AnnotationArray* annotations_typeArray, int &byte_i_ref) {
2293
2294 if ((byte_i_ref + 2) > annotations_typeArray->length()) {
2295 // not enough room for num_annotations field
2296 log_debug(redefine, class, annotation)("length() is too small for num_annotations field");
2297 return false;
2298 }
2299
2300 u2 num_annotations = Bytes::get_Java_u2((address)
2301 annotations_typeArray->adr_at(byte_i_ref));
2302 byte_i_ref += 2;
2303
2304 log_debug(redefine, class, annotation)("num_annotations=%d", num_annotations);
2305
2306 int calc_num_annotations = 0;
2307 for (; calc_num_annotations < num_annotations; calc_num_annotations++) {
2308 if (!rewrite_cp_refs_in_annotation_struct(annotations_typeArray, byte_i_ref)) {
2309 log_debug(redefine, class, annotation)("bad annotation_struct at %d", calc_num_annotations);
2310 // propagate failure back to caller
2311 return false;
2312 }
2313 }
2314 assert(num_annotations == calc_num_annotations, "sanity check");
2315
2316 return true;
2317 } // end rewrite_cp_refs_in_annotations_typeArray()
2318
2319
2320 // Rewrite constant pool references in the annotation struct portion of
2321 // an annotations_typeArray. This "structure" is from section 4.8.15 of
2322 // the 2nd-edition of the VM spec:
2323 //
2324 // struct annotation {
2325 // u2 type_index;
2326 // u2 num_element_value_pairs;
2327 // {
2328 // u2 element_name_index;
2329 // element_value value;
2330 // } element_value_pairs[num_element_value_pairs];
2331 // }
2332 //
2333 bool VM_RedefineClasses::rewrite_cp_refs_in_annotation_struct(
2334 AnnotationArray* annotations_typeArray, int &byte_i_ref) {
2335 if ((byte_i_ref + 2 + 2) > annotations_typeArray->length()) {
2336 // not enough room for smallest annotation_struct
2337 log_debug(redefine, class, annotation)("length() is too small for annotation_struct");
2338 return false;
2339 }
2340
2341 u2 type_index = rewrite_cp_ref_in_annotation_data(annotations_typeArray,
2342 byte_i_ref, "type_index");
2343
2344 u2 num_element_value_pairs = Bytes::get_Java_u2((address)
2345 annotations_typeArray->adr_at(byte_i_ref));
2346 byte_i_ref += 2;
2347
2348 log_debug(redefine, class, annotation)
2349 ("type_index=%d num_element_value_pairs=%d", type_index, num_element_value_pairs);
2350
2351 int calc_num_element_value_pairs = 0;
2352 for (; calc_num_element_value_pairs < num_element_value_pairs;
2353 calc_num_element_value_pairs++) {
2354 if ((byte_i_ref + 2) > annotations_typeArray->length()) {
2355 // not enough room for another element_name_index, let alone
2356 // the rest of another component
2357 log_debug(redefine, class, annotation)("length() is too small for element_name_index");
2358 return false;
2359 }
2360
2361 u2 element_name_index = rewrite_cp_ref_in_annotation_data(
2362 annotations_typeArray, byte_i_ref,
2363 "element_name_index");
2364
2365 log_debug(redefine, class, annotation)("element_name_index=%d", element_name_index);
2366
2367 if (!rewrite_cp_refs_in_element_value(annotations_typeArray, byte_i_ref)) {
2368 log_debug(redefine, class, annotation)("bad element_value at %d", calc_num_element_value_pairs);
2369 // propagate failure back to caller
2370 return false;
2371 }
2372 } // end for each component
2373 assert(num_element_value_pairs == calc_num_element_value_pairs,
2374 "sanity check");
2375
2376 return true;
2377 } // end rewrite_cp_refs_in_annotation_struct()
2378
2379
2380 // Rewrite a constant pool reference at the current position in
2381 // annotations_typeArray if needed. Returns the original constant
2382 // pool reference if a rewrite was not needed or the new constant
2383 // pool reference if a rewrite was needed.
2384 u2 VM_RedefineClasses::rewrite_cp_ref_in_annotation_data(
2385 AnnotationArray* annotations_typeArray, int &byte_i_ref,
2386 const char * trace_mesg) {
2387
2388 address cp_index_addr = (address)
2389 annotations_typeArray->adr_at(byte_i_ref);
2390 u2 old_cp_index = Bytes::get_Java_u2(cp_index_addr);
2391 u2 new_cp_index = find_new_index(old_cp_index);
2392 if (new_cp_index != 0) {
2393 log_debug(redefine, class, annotation)("mapped old %s=%d", trace_mesg, old_cp_index);
2394 Bytes::put_Java_u2(cp_index_addr, new_cp_index);
2395 old_cp_index = new_cp_index;
2396 }
2397 byte_i_ref += 2;
2398 return old_cp_index;
2399 }
2400
2401
2402 // Rewrite constant pool references in the element_value portion of an
2403 // annotations_typeArray. This "structure" is from section 4.8.15.1 of
2404 // the 2nd-edition of the VM spec:
2405 //
2406 // struct element_value {
2407 // u1 tag;
2408 // union {
2409 // u2 const_value_index;
2410 // {
2411 // u2 type_name_index;
2412 // u2 const_name_index;
2413 // } enum_const_value;
2414 // u2 class_info_index;
2415 // annotation annotation_value;
2416 // struct {
2417 // u2 num_values;
2418 // element_value values[num_values];
2419 // } array_value;
2420 // } value;
2421 // }
2422 //
2423 bool VM_RedefineClasses::rewrite_cp_refs_in_element_value(
2424 AnnotationArray* annotations_typeArray, int &byte_i_ref) {
2425
2426 if ((byte_i_ref + 1) > annotations_typeArray->length()) {
2427 // not enough room for a tag let alone the rest of an element_value
2428 log_debug(redefine, class, annotation)("length() is too small for a tag");
2429 return false;
2430 }
2431
2432 u1 tag = annotations_typeArray->at(byte_i_ref);
2433 byte_i_ref++;
2434 log_debug(redefine, class, annotation)("tag='%c'", tag);
2435
2436 switch (tag) {
2437 // These BaseType tag values are from Table 4.2 in VM spec:
2438 case JVM_SIGNATURE_BYTE:
2439 case JVM_SIGNATURE_CHAR:
2440 case JVM_SIGNATURE_DOUBLE:
2441 case JVM_SIGNATURE_FLOAT:
2442 case JVM_SIGNATURE_INT:
2443 case JVM_SIGNATURE_LONG:
2444 case JVM_SIGNATURE_SHORT:
2445 case JVM_SIGNATURE_BOOLEAN:
2446
2447 // The remaining tag values are from Table 4.8 in the 2nd-edition of
2448 // the VM spec:
2449 case 's':
2450 {
2451 // For the above tag values (including the BaseType values),
2452 // value.const_value_index is right union field.
2453
2454 if ((byte_i_ref + 2) > annotations_typeArray->length()) {
2455 // not enough room for a const_value_index
2456 log_debug(redefine, class, annotation)("length() is too small for a const_value_index");
2457 return false;
2458 }
2459
2460 u2 const_value_index = rewrite_cp_ref_in_annotation_data(
2461 annotations_typeArray, byte_i_ref,
2462 "const_value_index");
2463
2464 log_debug(redefine, class, annotation)("const_value_index=%d", const_value_index);
2465 } break;
2466
2467 case 'e':
2468 {
2469 // for the above tag value, value.enum_const_value is right union field
2470
2471 if ((byte_i_ref + 4) > annotations_typeArray->length()) {
2472 // not enough room for a enum_const_value
2473 log_debug(redefine, class, annotation)("length() is too small for a enum_const_value");
2474 return false;
2475 }
2476
2477 u2 type_name_index = rewrite_cp_ref_in_annotation_data(
2478 annotations_typeArray, byte_i_ref,
2479 "type_name_index");
2480
2481 u2 const_name_index = rewrite_cp_ref_in_annotation_data(
2482 annotations_typeArray, byte_i_ref,
2483 "const_name_index");
2484
2485 log_debug(redefine, class, annotation)
2486 ("type_name_index=%d const_name_index=%d", type_name_index, const_name_index);
2487 } break;
2488
2489 case 'c':
2490 {
2491 // for the above tag value, value.class_info_index is right union field
2492
2493 if ((byte_i_ref + 2) > annotations_typeArray->length()) {
2494 // not enough room for a class_info_index
2495 log_debug(redefine, class, annotation)("length() is too small for a class_info_index");
2496 return false;
2497 }
2498
2499 u2 class_info_index = rewrite_cp_ref_in_annotation_data(
2500 annotations_typeArray, byte_i_ref,
2501 "class_info_index");
2502
2503 log_debug(redefine, class, annotation)("class_info_index=%d", class_info_index);
2504 } break;
2505
2506 case '@':
2507 // For the above tag value, value.attr_value is the right union
2508 // field. This is a nested annotation.
2509 if (!rewrite_cp_refs_in_annotation_struct(annotations_typeArray, byte_i_ref)) {
2510 // propagate failure back to caller
2511 return false;
2512 }
2513 break;
2514
2515 case JVM_SIGNATURE_ARRAY:
2516 {
2517 if ((byte_i_ref + 2) > annotations_typeArray->length()) {
2518 // not enough room for a num_values field
2519 log_debug(redefine, class, annotation)("length() is too small for a num_values field");
2520 return false;
2521 }
2522
2523 // For the above tag value, value.array_value is the right union
2524 // field. This is an array of nested element_value.
2525 u2 num_values = Bytes::get_Java_u2((address)
2526 annotations_typeArray->adr_at(byte_i_ref));
2527 byte_i_ref += 2;
2528 log_debug(redefine, class, annotation)("num_values=%d", num_values);
2529
2530 int calc_num_values = 0;
2531 for (; calc_num_values < num_values; calc_num_values++) {
2532 if (!rewrite_cp_refs_in_element_value(annotations_typeArray, byte_i_ref)) {
2533 log_debug(redefine, class, annotation)("bad nested element_value at %d", calc_num_values);
2534 // propagate failure back to caller
2535 return false;
2536 }
2537 }
2538 assert(num_values == calc_num_values, "sanity check");
2539 } break;
2540
2541 default:
2542 log_debug(redefine, class, annotation)("bad tag=0x%x", tag);
2543 return false;
2544 } // end decode tag field
2545
2546 return true;
2547 } // end rewrite_cp_refs_in_element_value()
2548
2549
2550 // Rewrite constant pool references in a fields_annotations field.
2551 bool VM_RedefineClasses::rewrite_cp_refs_in_fields_annotations(
2552 InstanceKlass* scratch_class) {
2553
2554 Array<AnnotationArray*>* fields_annotations = scratch_class->fields_annotations();
2555
2556 if (fields_annotations == nullptr || fields_annotations->length() == 0) {
2557 // no fields_annotations so nothing to do
2558 return true;
2559 }
2560
2561 log_debug(redefine, class, annotation)("fields_annotations length=%d", fields_annotations->length());
2562
2563 for (int i = 0; i < fields_annotations->length(); i++) {
2564 AnnotationArray* field_annotations = fields_annotations->at(i);
2565 if (field_annotations == nullptr || field_annotations->length() == 0) {
2566 // this field does not have any annotations so skip it
2567 continue;
2568 }
2569
2570 int byte_i = 0; // byte index into field_annotations
2571 if (!rewrite_cp_refs_in_annotations_typeArray(field_annotations, byte_i)) {
2572 log_debug(redefine, class, annotation)("bad field_annotations at %d", i);
2573 // propagate failure back to caller
2574 return false;
2575 }
2576 }
2577
2578 return true;
2579 } // end rewrite_cp_refs_in_fields_annotations()
2580
2581
2582 // Rewrite constant pool references in a methods_annotations field.
2583 bool VM_RedefineClasses::rewrite_cp_refs_in_methods_annotations(
2584 InstanceKlass* scratch_class) {
2585
2586 for (int i = 0; i < scratch_class->methods()->length(); i++) {
2587 Method* m = scratch_class->methods()->at(i);
2588 AnnotationArray* method_annotations = m->constMethod()->method_annotations();
2589
2590 if (method_annotations == nullptr || method_annotations->length() == 0) {
2591 // this method does not have any annotations so skip it
2592 continue;
2593 }
2594
2595 int byte_i = 0; // byte index into method_annotations
2596 if (!rewrite_cp_refs_in_annotations_typeArray(method_annotations, byte_i)) {
2597 log_debug(redefine, class, annotation)("bad method_annotations at %d", i);
2598 // propagate failure back to caller
2599 return false;
2600 }
2601 }
2602
2603 return true;
2604 } // end rewrite_cp_refs_in_methods_annotations()
2605
2606
2607 // Rewrite constant pool references in a methods_parameter_annotations
2608 // field. This "structure" is adapted from the
2609 // RuntimeVisibleParameterAnnotations_attribute described in section
2610 // 4.8.17 of the 2nd-edition of the VM spec:
2611 //
2612 // methods_parameter_annotations_typeArray {
2613 // u1 num_parameters;
2614 // {
2615 // u2 num_annotations;
2616 // annotation annotations[num_annotations];
2617 // } parameter_annotations[num_parameters];
2618 // }
2619 //
2620 bool VM_RedefineClasses::rewrite_cp_refs_in_methods_parameter_annotations(
2621 InstanceKlass* scratch_class) {
2622
2623 for (int i = 0; i < scratch_class->methods()->length(); i++) {
2624 Method* m = scratch_class->methods()->at(i);
2625 AnnotationArray* method_parameter_annotations = m->constMethod()->parameter_annotations();
2626 if (method_parameter_annotations == nullptr
2627 || method_parameter_annotations->length() == 0) {
2628 // this method does not have any parameter annotations so skip it
2629 continue;
2630 }
2631
2632 if (method_parameter_annotations->length() < 1) {
2633 // not enough room for a num_parameters field
2634 log_debug(redefine, class, annotation)("length() is too small for a num_parameters field at %d", i);
2635 return false;
2636 }
2637
2638 int byte_i = 0; // byte index into method_parameter_annotations
2639
2640 u1 num_parameters = method_parameter_annotations->at(byte_i);
2641 byte_i++;
2642
2643 log_debug(redefine, class, annotation)("num_parameters=%d", num_parameters);
2644
2645 int calc_num_parameters = 0;
2646 for (; calc_num_parameters < num_parameters; calc_num_parameters++) {
2647 if (!rewrite_cp_refs_in_annotations_typeArray(method_parameter_annotations, byte_i)) {
2648 log_debug(redefine, class, annotation)("bad method_parameter_annotations at %d", calc_num_parameters);
2649 // propagate failure back to caller
2650 return false;
2651 }
2652 }
2653 assert(num_parameters == calc_num_parameters, "sanity check");
2654 }
2655
2656 return true;
2657 } // end rewrite_cp_refs_in_methods_parameter_annotations()
2658
2659
2660 // Rewrite constant pool references in a methods_default_annotations
2661 // field. This "structure" is adapted from the AnnotationDefault_attribute
2662 // that is described in section 4.8.19 of the 2nd-edition of the VM spec:
2663 //
2664 // methods_default_annotations_typeArray {
2665 // element_value default_value;
2666 // }
2667 //
2668 bool VM_RedefineClasses::rewrite_cp_refs_in_methods_default_annotations(
2669 InstanceKlass* scratch_class) {
2670
2671 for (int i = 0; i < scratch_class->methods()->length(); i++) {
2672 Method* m = scratch_class->methods()->at(i);
2673 AnnotationArray* method_default_annotations = m->constMethod()->default_annotations();
2674 if (method_default_annotations == nullptr
2675 || method_default_annotations->length() == 0) {
2676 // this method does not have any default annotations so skip it
2677 continue;
2678 }
2679
2680 int byte_i = 0; // byte index into method_default_annotations
2681
2682 if (!rewrite_cp_refs_in_element_value(
2683 method_default_annotations, byte_i)) {
2684 log_debug(redefine, class, annotation)("bad default element_value at %d", i);
2685 // propagate failure back to caller
2686 return false;
2687 }
2688 }
2689
2690 return true;
2691 } // end rewrite_cp_refs_in_methods_default_annotations()
2692
2693
2694 // Rewrite constant pool references in a class_type_annotations field.
2695 bool VM_RedefineClasses::rewrite_cp_refs_in_class_type_annotations(
2696 InstanceKlass* scratch_class) {
2697
2698 AnnotationArray* class_type_annotations = scratch_class->class_type_annotations();
2699 if (class_type_annotations == nullptr || class_type_annotations->length() == 0) {
2700 // no class_type_annotations so nothing to do
2701 return true;
2702 }
2703
2704 log_debug(redefine, class, annotation)("class_type_annotations length=%d", class_type_annotations->length());
2705
2706 int byte_i = 0; // byte index into class_type_annotations
2707 return rewrite_cp_refs_in_type_annotations_typeArray(class_type_annotations,
2708 byte_i, "ClassFile");
2709 } // end rewrite_cp_refs_in_class_type_annotations()
2710
2711
2712 // Rewrite constant pool references in a fields_type_annotations field.
2713 bool VM_RedefineClasses::rewrite_cp_refs_in_fields_type_annotations(InstanceKlass* scratch_class) {
2714
2715 Array<AnnotationArray*>* fields_type_annotations = scratch_class->fields_type_annotations();
2716 if (fields_type_annotations == nullptr || fields_type_annotations->length() == 0) {
2717 // no fields_type_annotations so nothing to do
2718 return true;
2719 }
2720
2721 log_debug(redefine, class, annotation)("fields_type_annotations length=%d", fields_type_annotations->length());
2722
2723 for (int i = 0; i < fields_type_annotations->length(); i++) {
2724 AnnotationArray* field_type_annotations = fields_type_annotations->at(i);
2725 if (field_type_annotations == nullptr || field_type_annotations->length() == 0) {
2726 // this field does not have any annotations so skip it
2727 continue;
2728 }
2729
2730 int byte_i = 0; // byte index into field_type_annotations
2731 if (!rewrite_cp_refs_in_type_annotations_typeArray(field_type_annotations,
2732 byte_i, "field_info")) {
2733 log_debug(redefine, class, annotation)("bad field_type_annotations at %d", i);
2734 // propagate failure back to caller
2735 return false;
2736 }
2737 }
2738
2739 return true;
2740 } // end rewrite_cp_refs_in_fields_type_annotations()
2741
2742
2743 // Rewrite constant pool references in a methods_type_annotations field.
2744 bool VM_RedefineClasses::rewrite_cp_refs_in_methods_type_annotations(
2745 InstanceKlass* scratch_class) {
2746
2747 for (int i = 0; i < scratch_class->methods()->length(); i++) {
2748 Method* m = scratch_class->methods()->at(i);
2749 AnnotationArray* method_type_annotations = m->constMethod()->type_annotations();
2750
2751 if (method_type_annotations == nullptr || method_type_annotations->length() == 0) {
2752 // this method does not have any annotations so skip it
2753 continue;
2754 }
2755
2756 log_debug(redefine, class, annotation)("methods type_annotations length=%d", method_type_annotations->length());
2757
2758 int byte_i = 0; // byte index into method_type_annotations
2759 if (!rewrite_cp_refs_in_type_annotations_typeArray(method_type_annotations,
2760 byte_i, "method_info")) {
2761 log_debug(redefine, class, annotation)("bad method_type_annotations at %d", i);
2762 // propagate failure back to caller
2763 return false;
2764 }
2765 }
2766
2767 return true;
2768 } // end rewrite_cp_refs_in_methods_type_annotations()
2769
2770
2771 // Rewrite constant pool references in a type_annotations
2772 // field. This "structure" is adapted from the
2773 // RuntimeVisibleTypeAnnotations_attribute described in
2774 // section 4.7.20 of the Java SE 8 Edition of the VM spec:
2775 //
2776 // type_annotations_typeArray {
2777 // u2 num_annotations;
2778 // type_annotation annotations[num_annotations];
2779 // }
2780 //
2781 bool VM_RedefineClasses::rewrite_cp_refs_in_type_annotations_typeArray(
2782 AnnotationArray* type_annotations_typeArray, int &byte_i_ref,
2783 const char * location_mesg) {
2784
2785 if ((byte_i_ref + 2) > type_annotations_typeArray->length()) {
2786 // not enough room for num_annotations field
2787 log_debug(redefine, class, annotation)("length() is too small for num_annotations field");
2788 return false;
2789 }
2790
2791 u2 num_annotations = Bytes::get_Java_u2((address)
2792 type_annotations_typeArray->adr_at(byte_i_ref));
2793 byte_i_ref += 2;
2794
2795 log_debug(redefine, class, annotation)("num_type_annotations=%d", num_annotations);
2796
2797 int calc_num_annotations = 0;
2798 for (; calc_num_annotations < num_annotations; calc_num_annotations++) {
2799 if (!rewrite_cp_refs_in_type_annotation_struct(type_annotations_typeArray,
2800 byte_i_ref, location_mesg)) {
2801 log_debug(redefine, class, annotation)("bad type_annotation_struct at %d", calc_num_annotations);
2802 // propagate failure back to caller
2803 return false;
2804 }
2805 }
2806 assert(num_annotations == calc_num_annotations, "sanity check");
2807
2808 if (byte_i_ref != type_annotations_typeArray->length()) {
2809 log_debug(redefine, class, annotation)
2810 ("read wrong amount of bytes at end of processing type_annotations_typeArray (%d of %d bytes were read)",
2811 byte_i_ref, type_annotations_typeArray->length());
2812 return false;
2813 }
2814
2815 return true;
2816 } // end rewrite_cp_refs_in_type_annotations_typeArray()
2817
2818
2819 // Rewrite constant pool references in a type_annotation
2820 // field. This "structure" is adapted from the
2821 // RuntimeVisibleTypeAnnotations_attribute described in
2822 // section 4.7.20 of the Java SE 8 Edition of the VM spec:
2823 //
2824 // type_annotation {
2825 // u1 target_type;
2826 // union {
2827 // type_parameter_target;
2828 // supertype_target;
2829 // type_parameter_bound_target;
2830 // empty_target;
2831 // method_formal_parameter_target;
2832 // throws_target;
2833 // localvar_target;
2834 // catch_target;
2835 // offset_target;
2836 // type_argument_target;
2837 // } target_info;
2838 // type_path target_path;
2839 // annotation anno;
2840 // }
2841 //
2842 bool VM_RedefineClasses::rewrite_cp_refs_in_type_annotation_struct(
2843 AnnotationArray* type_annotations_typeArray, int &byte_i_ref,
2844 const char * location_mesg) {
2845
2846 if (!skip_type_annotation_target(type_annotations_typeArray,
2847 byte_i_ref, location_mesg)) {
2848 return false;
2849 }
2850
2851 if (!skip_type_annotation_type_path(type_annotations_typeArray, byte_i_ref)) {
2852 return false;
2853 }
2854
2855 if (!rewrite_cp_refs_in_annotation_struct(type_annotations_typeArray, byte_i_ref)) {
2856 return false;
2857 }
2858
2859 return true;
2860 } // end rewrite_cp_refs_in_type_annotation_struct()
2861
2862
2863 // Read, verify and skip over the target_type and target_info part
2864 // so that rewriting can continue in the later parts of the struct.
2865 //
2866 // u1 target_type;
2867 // union {
2868 // type_parameter_target;
2869 // supertype_target;
2870 // type_parameter_bound_target;
2871 // empty_target;
2872 // method_formal_parameter_target;
2873 // throws_target;
2874 // localvar_target;
2875 // catch_target;
2876 // offset_target;
2877 // type_argument_target;
2878 // } target_info;
2879 //
2880 bool VM_RedefineClasses::skip_type_annotation_target(
2881 AnnotationArray* type_annotations_typeArray, int &byte_i_ref,
2882 const char * location_mesg) {
2883
2884 if ((byte_i_ref + 1) > type_annotations_typeArray->length()) {
2885 // not enough room for a target_type let alone the rest of a type_annotation
2886 log_debug(redefine, class, annotation)("length() is too small for a target_type");
2887 return false;
2888 }
2889
2890 u1 target_type = type_annotations_typeArray->at(byte_i_ref);
2891 byte_i_ref += 1;
2892 log_debug(redefine, class, annotation)("target_type=0x%.2x", target_type);
2893 log_debug(redefine, class, annotation)("location=%s", location_mesg);
2894
2895 // Skip over target_info
2896 switch (target_type) {
2897 case 0x00:
2898 // kind: type parameter declaration of generic class or interface
2899 // location: ClassFile
2900 case 0x01:
2901 // kind: type parameter declaration of generic method or constructor
2902 // location: method_info
2903
2904 {
2905 // struct:
2906 // type_parameter_target {
2907 // u1 type_parameter_index;
2908 // }
2909 //
2910 if ((byte_i_ref + 1) > type_annotations_typeArray->length()) {
2911 log_debug(redefine, class, annotation)("length() is too small for a type_parameter_target");
2912 return false;
2913 }
2914
2915 u1 type_parameter_index = type_annotations_typeArray->at(byte_i_ref);
2916 byte_i_ref += 1;
2917
2918 log_debug(redefine, class, annotation)("type_parameter_target: type_parameter_index=%d", type_parameter_index);
2919 } break;
2920
2921 case 0x10:
2922 // kind: type in extends clause of class or interface declaration
2923 // or in implements clause of interface declaration
2924 // location: ClassFile
2925
2926 {
2927 // struct:
2928 // supertype_target {
2929 // u2 supertype_index;
2930 // }
2931 //
2932 if ((byte_i_ref + 2) > type_annotations_typeArray->length()) {
2933 log_debug(redefine, class, annotation)("length() is too small for a supertype_target");
2934 return false;
2935 }
2936
2937 u2 supertype_index = Bytes::get_Java_u2((address)
2938 type_annotations_typeArray->adr_at(byte_i_ref));
2939 byte_i_ref += 2;
2940
2941 log_debug(redefine, class, annotation)("supertype_target: supertype_index=%d", supertype_index);
2942 } break;
2943
2944 case 0x11:
2945 // kind: type in bound of type parameter declaration of generic class or interface
2946 // location: ClassFile
2947 case 0x12:
2948 // kind: type in bound of type parameter declaration of generic method or constructor
2949 // location: method_info
2950
2951 {
2952 // struct:
2953 // type_parameter_bound_target {
2954 // u1 type_parameter_index;
2955 // u1 bound_index;
2956 // }
2957 //
2958 if ((byte_i_ref + 2) > type_annotations_typeArray->length()) {
2959 log_debug(redefine, class, annotation)("length() is too small for a type_parameter_bound_target");
2960 return false;
2961 }
2962
2963 u1 type_parameter_index = type_annotations_typeArray->at(byte_i_ref);
2964 byte_i_ref += 1;
2965 u1 bound_index = type_annotations_typeArray->at(byte_i_ref);
2966 byte_i_ref += 1;
2967
2968 log_debug(redefine, class, annotation)
2969 ("type_parameter_bound_target: type_parameter_index=%d, bound_index=%d", type_parameter_index, bound_index);
2970 } break;
2971
2972 case 0x13:
2973 // kind: type in field declaration
2974 // location: field_info
2975 case 0x14:
2976 // kind: return type of method, or type of newly constructed object
2977 // location: method_info
2978 case 0x15:
2979 // kind: receiver type of method or constructor
2980 // location: method_info
2981
2982 {
2983 // struct:
2984 // empty_target {
2985 // }
2986 //
2987 log_debug(redefine, class, annotation)("empty_target");
2988 } break;
2989
2990 case 0x16:
2991 // kind: type in formal parameter declaration of method, constructor, or lambda expression
2992 // location: method_info
2993
2994 {
2995 // struct:
2996 // formal_parameter_target {
2997 // u1 formal_parameter_index;
2998 // }
2999 //
3000 if ((byte_i_ref + 1) > type_annotations_typeArray->length()) {
3001 log_debug(redefine, class, annotation)("length() is too small for a formal_parameter_target");
3002 return false;
3003 }
3004
3005 u1 formal_parameter_index = type_annotations_typeArray->at(byte_i_ref);
3006 byte_i_ref += 1;
3007
3008 log_debug(redefine, class, annotation)
3009 ("formal_parameter_target: formal_parameter_index=%d", formal_parameter_index);
3010 } break;
3011
3012 case 0x17:
3013 // kind: type in throws clause of method or constructor
3014 // location: method_info
3015
3016 {
3017 // struct:
3018 // throws_target {
3019 // u2 throws_type_index
3020 // }
3021 //
3022 if ((byte_i_ref + 2) > type_annotations_typeArray->length()) {
3023 log_debug(redefine, class, annotation)("length() is too small for a throws_target");
3024 return false;
3025 }
3026
3027 u2 throws_type_index = Bytes::get_Java_u2((address)
3028 type_annotations_typeArray->adr_at(byte_i_ref));
3029 byte_i_ref += 2;
3030
3031 log_debug(redefine, class, annotation)("throws_target: throws_type_index=%d", throws_type_index);
3032 } break;
3033
3034 case 0x40:
3035 // kind: type in local variable declaration
3036 // location: Code
3037 case 0x41:
3038 // kind: type in resource variable declaration
3039 // location: Code
3040
3041 {
3042 // struct:
3043 // localvar_target {
3044 // u2 table_length;
3045 // struct {
3046 // u2 start_pc;
3047 // u2 length;
3048 // u2 index;
3049 // } table[table_length];
3050 // }
3051 //
3052 if ((byte_i_ref + 2) > type_annotations_typeArray->length()) {
3053 // not enough room for a table_length let alone the rest of a localvar_target
3054 log_debug(redefine, class, annotation)("length() is too small for a localvar_target table_length");
3055 return false;
3056 }
3057
3058 u2 table_length = Bytes::get_Java_u2((address)
3059 type_annotations_typeArray->adr_at(byte_i_ref));
3060 byte_i_ref += 2;
3061
3062 log_debug(redefine, class, annotation)("localvar_target: table_length=%d", table_length);
3063
3064 int table_struct_size = 2 + 2 + 2; // 3 u2 variables per table entry
3065 int table_size = table_length * table_struct_size;
3066
3067 if ((byte_i_ref + table_size) > type_annotations_typeArray->length()) {
3068 // not enough room for a table
3069 log_debug(redefine, class, annotation)("length() is too small for a table array of length %d", table_length);
3070 return false;
3071 }
3072
3073 // Skip over table
3074 byte_i_ref += table_size;
3075 } break;
3076
3077 case 0x42:
3078 // kind: type in exception parameter declaration
3079 // location: Code
3080
3081 {
3082 // struct:
3083 // catch_target {
3084 // u2 exception_table_index;
3085 // }
3086 //
3087 if ((byte_i_ref + 2) > type_annotations_typeArray->length()) {
3088 log_debug(redefine, class, annotation)("length() is too small for a catch_target");
3089 return false;
3090 }
3091
3092 u2 exception_table_index = Bytes::get_Java_u2((address)
3093 type_annotations_typeArray->adr_at(byte_i_ref));
3094 byte_i_ref += 2;
3095
3096 log_debug(redefine, class, annotation)("catch_target: exception_table_index=%d", exception_table_index);
3097 } break;
3098
3099 case 0x43:
3100 // kind: type in instanceof expression
3101 // location: Code
3102 case 0x44:
3103 // kind: type in new expression
3104 // location: Code
3105 case 0x45:
3106 // kind: type in method reference expression using ::new
3107 // location: Code
3108 case 0x46:
3109 // kind: type in method reference expression using ::Identifier
3110 // location: Code
3111
3112 {
3113 // struct:
3114 // offset_target {
3115 // u2 offset;
3116 // }
3117 //
3118 if ((byte_i_ref + 2) > type_annotations_typeArray->length()) {
3119 log_debug(redefine, class, annotation)("length() is too small for a offset_target");
3120 return false;
3121 }
3122
3123 u2 offset = Bytes::get_Java_u2((address)
3124 type_annotations_typeArray->adr_at(byte_i_ref));
3125 byte_i_ref += 2;
3126
3127 log_debug(redefine, class, annotation)("offset_target: offset=%d", offset);
3128 } break;
3129
3130 case 0x47:
3131 // kind: type in cast expression
3132 // location: Code
3133 case 0x48:
3134 // kind: type argument for generic constructor in new expression or
3135 // explicit constructor invocation statement
3136 // location: Code
3137 case 0x49:
3138 // kind: type argument for generic method in method invocation expression
3139 // location: Code
3140 case 0x4A:
3141 // kind: type argument for generic constructor in method reference expression using ::new
3142 // location: Code
3143 case 0x4B:
3144 // kind: type argument for generic method in method reference expression using ::Identifier
3145 // location: Code
3146
3147 {
3148 // struct:
3149 // type_argument_target {
3150 // u2 offset;
3151 // u1 type_argument_index;
3152 // }
3153 //
3154 if ((byte_i_ref + 3) > type_annotations_typeArray->length()) {
3155 log_debug(redefine, class, annotation)("length() is too small for a type_argument_target");
3156 return false;
3157 }
3158
3159 u2 offset = Bytes::get_Java_u2((address)
3160 type_annotations_typeArray->adr_at(byte_i_ref));
3161 byte_i_ref += 2;
3162 u1 type_argument_index = type_annotations_typeArray->at(byte_i_ref);
3163 byte_i_ref += 1;
3164
3165 log_debug(redefine, class, annotation)
3166 ("type_argument_target: offset=%d, type_argument_index=%d", offset, type_argument_index);
3167 } break;
3168
3169 default:
3170 log_debug(redefine, class, annotation)("unknown target_type");
3171 #ifdef ASSERT
3172 ShouldNotReachHere();
3173 #endif
3174 return false;
3175 }
3176
3177 return true;
3178 } // end skip_type_annotation_target()
3179
3180
3181 // Read, verify and skip over the type_path part so that rewriting
3182 // can continue in the later parts of the struct.
3183 //
3184 // type_path {
3185 // u1 path_length;
3186 // {
3187 // u1 type_path_kind;
3188 // u1 type_argument_index;
3189 // } path[path_length];
3190 // }
3191 //
3192 bool VM_RedefineClasses::skip_type_annotation_type_path(
3193 AnnotationArray* type_annotations_typeArray, int &byte_i_ref) {
3194
3195 if ((byte_i_ref + 1) > type_annotations_typeArray->length()) {
3196 // not enough room for a path_length let alone the rest of the type_path
3197 log_debug(redefine, class, annotation)("length() is too small for a type_path");
3198 return false;
3199 }
3200
3201 u1 path_length = type_annotations_typeArray->at(byte_i_ref);
3202 byte_i_ref += 1;
3203
3204 log_debug(redefine, class, annotation)("type_path: path_length=%d", path_length);
3205
3206 int calc_path_length = 0;
3207 for (; calc_path_length < path_length; calc_path_length++) {
3208 if ((byte_i_ref + 1 + 1) > type_annotations_typeArray->length()) {
3209 // not enough room for a path
3210 log_debug(redefine, class, annotation)
3211 ("length() is too small for path entry %d of %d", calc_path_length, path_length);
3212 return false;
3213 }
3214
3215 u1 type_path_kind = type_annotations_typeArray->at(byte_i_ref);
3216 byte_i_ref += 1;
3217 u1 type_argument_index = type_annotations_typeArray->at(byte_i_ref);
3218 byte_i_ref += 1;
3219
3220 log_debug(redefine, class, annotation)
3221 ("type_path: path[%d]: type_path_kind=%d, type_argument_index=%d",
3222 calc_path_length, type_path_kind, type_argument_index);
3223
3224 if (type_path_kind > 3 || (type_path_kind != 3 && type_argument_index != 0)) {
3225 // not enough room for a path
3226 log_debug(redefine, class, annotation)("inconsistent type_path values");
3227 return false;
3228 }
3229 }
3230 assert(path_length == calc_path_length, "sanity check");
3231
3232 return true;
3233 } // end skip_type_annotation_type_path()
3234
3235
3236 // Rewrite constant pool references in the method's stackmap table.
3237 // These "structures" are adapted from the StackMapTable_attribute that
3238 // is described in section 4.8.4 of the 6.0 version of the VM spec
3239 // (dated 2005.10.26):
3240 // file:///net/quincunx.sfbay/export/gbracha/ClassFile-Java6.pdf
3241 //
3242 // stack_map {
3243 // u2 number_of_entries;
3244 // stack_map_frame entries[number_of_entries];
3245 // }
3246 //
3247 void VM_RedefineClasses::rewrite_cp_refs_in_stack_map_table(
3248 const methodHandle& method) {
3249
3250 if (!method->has_stackmap_table()) {
3251 return;
3252 }
3253
3254 AnnotationArray* stackmap_data = method->stackmap_data();
3255 address stackmap_p = (address)stackmap_data->adr_at(0);
3256 address stackmap_end = stackmap_p + stackmap_data->length();
3257
3258 assert(stackmap_p + 2 <= stackmap_end, "no room for number_of_entries");
3259 u2 number_of_entries = Bytes::get_Java_u2(stackmap_p);
3260 stackmap_p += 2;
3261
3262 log_debug(redefine, class, stackmap)("number_of_entries=%u", number_of_entries);
3263
3264 // walk through each stack_map_frame
3265 u2 calc_number_of_entries = 0;
3266 for (; calc_number_of_entries < number_of_entries; calc_number_of_entries++) {
3267 // The stack_map_frame structure is a u1 frame_type followed by
3268 // 0 or more bytes of data:
3269 //
3270 // union stack_map_frame {
3271 // same_frame;
3272 // same_locals_1_stack_item_frame;
3273 // same_locals_1_stack_item_frame_extended;
3274 // chop_frame;
3275 // same_frame_extended;
3276 // append_frame;
3277 // full_frame;
3278 // }
3279
3280 assert(stackmap_p + 1 <= stackmap_end, "no room for frame_type");
3281 u1 frame_type = *stackmap_p;
3282 stackmap_p++;
3283
3284 if (frame_type == 246) { // EARLY_LARVAL
3285 // rewrite_cp_refs in unset fields and fall through.
3286 rewrite_cp_refs_in_early_larval_stackmaps(stackmap_p, stackmap_end, calc_number_of_entries, frame_type);
3287 // The larval frames point to the next frame, so advance to the next frame and fall through.
3288 frame_type = *stackmap_p;
3289 stackmap_p++;
3290 }
3291
3292 // same_frame {
3293 // u1 frame_type = SAME; /* 0-63 */
3294 // }
3295 if (frame_type <= StackMapReader::SAME_FRAME_END) {
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 >= StackMapReader::SAME_LOCALS_1_STACK_ITEM_FRAME_START &&
3304 frame_type <= StackMapReader::SAME_LOCALS_1_STACK_ITEM_FRAME_END) {
3305 rewrite_cp_refs_in_verification_type_info(stackmap_p, stackmap_end,
3306 calc_number_of_entries, frame_type);
3307 }
3308
3309 // reserved for future use
3310 else if (frame_type >= StackMapReader::RESERVED_START &&
3311 frame_type <= StackMapReader::RESERVED_END) {
3312 // nothing more to do for reserved frame_types
3313 }
3314
3315 // same_locals_1_stack_item_frame_extended {
3316 // u1 frame_type = SAME_LOCALS_1_STACK_ITEM_EXTENDED; /* 247 */
3317 // u2 offset_delta;
3318 // verification_type_info stack[1];
3319 // }
3320 else if (frame_type == StackMapReader::SAME_LOCALS_1_STACK_ITEM_EXTENDED) {
3321 stackmap_p += 2;
3322 rewrite_cp_refs_in_verification_type_info(stackmap_p, stackmap_end,
3323 calc_number_of_entries, frame_type);
3324 }
3325
3326 // chop_frame {
3327 // u1 frame_type = CHOP; /* 248-250 */
3328 // u2 offset_delta;
3329 // }
3330 else if (frame_type >= StackMapReader::CHOP_FRAME_START &&
3331 frame_type <= StackMapReader::CHOP_FRAME_END) {
3332 stackmap_p += 2;
3333 }
3334
3335 // same_frame_extended {
3336 // u1 frame_type = SAME_EXTENDED; /* 251 */
3337 // u2 offset_delta;
3338 // }
3339 else if (frame_type == StackMapReader::SAME_FRAME_EXTENDED) {
3340 stackmap_p += 2;
3341 }
3342
3343 // append_frame {
3344 // u1 frame_type = APPEND; /* 252-254 */
3345 // u2 offset_delta;
3346 // verification_type_info locals[frame_type - SAME_EXTENDED];
3347 // }
3348 else if (frame_type >= StackMapReader::APPEND_FRAME_START &&
3349 frame_type <= StackMapReader::APPEND_FRAME_END) {
3350 assert(stackmap_p + 2 <= stackmap_end,
3351 "no room for offset_delta");
3352 stackmap_p += 2;
3353 u1 len = frame_type - StackMapReader::APPEND_FRAME_START + 1;
3354 for (u1 i = 0; i < len; i++) {
3355 rewrite_cp_refs_in_verification_type_info(stackmap_p, stackmap_end,
3356 calc_number_of_entries, frame_type);
3357 }
3358 }
3359
3360 // full_frame {
3361 // u1 frame_type = FULL_FRAME; /* 255 */
3362 // u2 offset_delta;
3363 // u2 number_of_locals;
3364 // verification_type_info locals[number_of_locals];
3365 // u2 number_of_stack_items;
3366 // verification_type_info stack[number_of_stack_items];
3367 // }
3368 else if (frame_type == StackMapReader::FULL_FRAME) {
3369 assert(stackmap_p + 2 + 2 <= stackmap_end,
3370 "no room for smallest full_frame");
3371 stackmap_p += 2;
3372
3373 u2 number_of_locals = Bytes::get_Java_u2(stackmap_p);
3374 stackmap_p += 2;
3375
3376 for (u2 locals_i = 0; locals_i < number_of_locals; locals_i++) {
3377 rewrite_cp_refs_in_verification_type_info(stackmap_p, stackmap_end,
3378 calc_number_of_entries, frame_type);
3379 }
3380
3381 // Use the largest size for the number_of_stack_items, but only get
3382 // the right number of bytes.
3383 u2 number_of_stack_items = Bytes::get_Java_u2(stackmap_p);
3384 stackmap_p += 2;
3385
3386 for (u2 stack_i = 0; stack_i < number_of_stack_items; stack_i++) {
3387 rewrite_cp_refs_in_verification_type_info(stackmap_p, stackmap_end,
3388 calc_number_of_entries, frame_type);
3389 }
3390 }
3391 } // end while there is a stack_map_frame
3392 assert(number_of_entries == calc_number_of_entries, "sanity check");
3393 } // end rewrite_cp_refs_in_stack_map_table()
3394
3395
3396 // Rewrite constant pool references in the verification type info
3397 // portion of the method's stackmap table. These "structures" are
3398 // adapted from the StackMapTable_attribute that is described in
3399 // section 4.8.4 of the 6.0 version of the VM spec (dated 2005.10.26):
3400 // file:///net/quincunx.sfbay/export/gbracha/ClassFile-Java6.pdf
3401 //
3402 // The verification_type_info structure is a u1 tag followed by 0 or
3403 // more bytes of data:
3404 //
3405 // union verification_type_info {
3406 // Top_variable_info;
3407 // Integer_variable_info;
3408 // Float_variable_info;
3409 // Long_variable_info;
3410 // Double_variable_info;
3411 // Null_variable_info;
3412 // UninitializedThis_variable_info;
3413 // Object_variable_info;
3414 // Uninitialized_variable_info;
3415 // }
3416 //
3417 void VM_RedefineClasses::rewrite_cp_refs_in_verification_type_info(
3418 address& stackmap_p_ref, address stackmap_end, u2 frame_i,
3419 u1 frame_type) {
3420
3421 assert(stackmap_p_ref + 1 <= stackmap_end, "no room for tag");
3422 u1 tag = *stackmap_p_ref;
3423 stackmap_p_ref++;
3424
3425 switch (tag) {
3426 // Top_variable_info {
3427 // u1 tag = ITEM_Top; /* 0 */
3428 // }
3429 // verificationType.hpp has zero as ITEM_Bogus instead of ITEM_Top
3430 case 0: // fall through
3431
3432 // Integer_variable_info {
3433 // u1 tag = ITEM_Integer; /* 1 */
3434 // }
3435 case ITEM_Integer: // fall through
3436
3437 // Float_variable_info {
3438 // u1 tag = ITEM_Float; /* 2 */
3439 // }
3440 case ITEM_Float: // fall through
3441
3442 // Double_variable_info {
3443 // u1 tag = ITEM_Double; /* 3 */
3444 // }
3445 case ITEM_Double: // fall through
3446
3447 // Long_variable_info {
3448 // u1 tag = ITEM_Long; /* 4 */
3449 // }
3450 case ITEM_Long: // fall through
3451
3452 // Null_variable_info {
3453 // u1 tag = ITEM_Null; /* 5 */
3454 // }
3455 case ITEM_Null: // fall through
3456
3457 // UninitializedThis_variable_info {
3458 // u1 tag = ITEM_UninitializedThis; /* 6 */
3459 // }
3460 case ITEM_UninitializedThis:
3461 // nothing more to do for the above tag types
3462 break;
3463
3464 // Object_variable_info {
3465 // u1 tag = ITEM_Object; /* 7 */
3466 // u2 cpool_index;
3467 // }
3468 case ITEM_Object:
3469 {
3470 assert(stackmap_p_ref + 2 <= stackmap_end, "no room for cpool_index");
3471 u2 cpool_index = Bytes::get_Java_u2(stackmap_p_ref);
3472 u2 new_cp_index = find_new_index(cpool_index);
3473 if (new_cp_index != 0) {
3474 log_debug(redefine, class, stackmap)("mapped old cpool_index=%d", cpool_index);
3475 Bytes::put_Java_u2(stackmap_p_ref, new_cp_index);
3476 cpool_index = new_cp_index;
3477 }
3478 stackmap_p_ref += 2;
3479
3480 log_debug(redefine, class, stackmap)
3481 ("frame_i=%u, frame_type=%u, cpool_index=%d", frame_i, frame_type, cpool_index);
3482 } break;
3483
3484 // Uninitialized_variable_info {
3485 // u1 tag = ITEM_Uninitialized; /* 8 */
3486 // u2 offset;
3487 // }
3488 case ITEM_Uninitialized:
3489 assert(stackmap_p_ref + 2 <= stackmap_end, "no room for offset");
3490 stackmap_p_ref += 2;
3491 break;
3492
3493 default:
3494 log_debug(redefine, class, stackmap)("frame_i=%u, frame_type=%u, bad tag=0x%x", frame_i, frame_type, tag);
3495 ShouldNotReachHere();
3496 break;
3497 } // end switch (tag)
3498 } // end rewrite_cp_refs_in_verification_type_info()
3499
3500
3501 void VM_RedefineClasses::rewrite_cp_refs_in_early_larval_stackmaps(
3502 address& stackmap_p_ref, address stackmap_end, u2 frame_i,
3503 u1 frame_type) {
3504
3505 u2 num_early_larval_stackmaps = Bytes::get_Java_u2(stackmap_p_ref);
3506 stackmap_p_ref += 2;
3507
3508 for (u2 i = 0; i < num_early_larval_stackmaps; i++) {
3509
3510 u2 name_and_ref_index = Bytes::get_Java_u2(stackmap_p_ref);
3511 u2 new_cp_index = find_new_index(name_and_ref_index);
3512 if (new_cp_index != 0) {
3513 log_debug(redefine, class, stackmap)("mapped old name_and_ref_index=%d", name_and_ref_index);
3514 Bytes::put_Java_u2(stackmap_p_ref, new_cp_index);
3515 name_and_ref_index = new_cp_index;
3516 }
3517 log_debug(redefine, class, stackmap)
3518 ("frame_i=%u, frame_type=%u, name_and_ref_index=%d", frame_i, frame_type, name_and_ref_index);
3519
3520 stackmap_p_ref += 2;
3521 }
3522 } // rewrite_cp_refs_in_early_larval_stackmaps
3523
3524 // Change the constant pool associated with klass scratch_class to scratch_cp.
3525 // scratch_cp_length elements are copied from scratch_cp to a smaller constant pool
3526 // and the smaller constant pool is associated with scratch_class.
3527 void VM_RedefineClasses::set_new_constant_pool(
3528 ClassLoaderData* loader_data,
3529 InstanceKlass* scratch_class, constantPoolHandle scratch_cp,
3530 int scratch_cp_length, TRAPS) {
3531 assert(scratch_cp->length() >= scratch_cp_length, "sanity check");
3532
3533 // scratch_cp is a merged constant pool and has enough space for a
3534 // worst case merge situation. We want to associate the minimum
3535 // sized constant pool with the klass to save space.
3536 ConstantPool* cp = ConstantPool::allocate(loader_data, scratch_cp_length, CHECK);
3537 constantPoolHandle smaller_cp(THREAD, cp);
3538
3539 // preserve version() value in the smaller copy
3540 int version = scratch_cp->version();
3541 assert(version != 0, "sanity check");
3542 smaller_cp->set_version(version);
3543
3544 // attach klass to new constant pool
3545 // reference to the cp holder is needed for reallocating the BSM attribute
3546 smaller_cp->set_pool_holder(scratch_class);
3547
3548 smaller_cp->copy_fields(scratch_cp());
3549
3550 scratch_cp->copy_cp_to(1, scratch_cp_length - 1, smaller_cp, 1, THREAD);
3551 if (HAS_PENDING_EXCEPTION) {
3552 // Exception is handled in the caller
3553 loader_data->add_to_deallocate_list(smaller_cp());
3554 return;
3555 }
3556 scratch_cp = smaller_cp;
3557
3558 // attach new constant pool to klass
3559 scratch_class->set_constants(scratch_cp());
3560 scratch_cp->initialize_unresolved_klasses(loader_data, CHECK);
3561
3562 int i; // for portability
3563
3564 // update each field in klass to use new constant pool indices as needed
3565 int java_fields;
3566 int injected_fields;
3567 bool update_required = false;
3568 GrowableArray<FieldInfo>* fields = FieldInfoStream::create_FieldInfoArray(scratch_class->fieldinfo_stream(), &java_fields, &injected_fields);
3569 for (int i = 0; i < java_fields; i++) {
3570 FieldInfo* fi = fields->adr_at(i);
3571 jshort cur_index = fi->name_index();
3572 jshort new_index = find_new_index(cur_index);
3573 if (new_index != 0) {
3574 log_trace(redefine, class, constantpool)("field-name_index change: %d to %d", cur_index, new_index);
3575 fi->set_name_index(new_index);
3576 update_required = true;
3577 }
3578 cur_index = fi->signature_index();
3579 new_index = find_new_index(cur_index);
3580 if (new_index != 0) {
3581 log_trace(redefine, class, constantpool)("field-signature_index change: %d to %d", cur_index, new_index);
3582 fi->set_signature_index(new_index);
3583 update_required = true;
3584 }
3585 cur_index = fi->initializer_index();
3586 new_index = find_new_index(cur_index);
3587 if (new_index != 0) {
3588 log_trace(redefine, class, constantpool)("field-initval_index change: %d to %d", cur_index, new_index);
3589 fi->set_initializer_index(new_index);
3590 update_required = true;
3591 }
3592 cur_index = fi->generic_signature_index();
3593 new_index = find_new_index(cur_index);
3594 if (new_index != 0) {
3595 log_trace(redefine, class, constantpool)("field-generic_signature change: %d to %d", cur_index, new_index);
3596 fi->set_generic_signature_index(new_index);
3597 update_required = true;
3598 }
3599 }
3600 if (update_required) {
3601 Array<u1>* old_stream = scratch_class->fieldinfo_stream();
3602 assert(fields->length() == (java_fields + injected_fields), "Must be");
3603 Array<u1>* new_fis = FieldInfoStream::create_FieldInfoStream(fields, java_fields, injected_fields, scratch_class->class_loader_data(), CHECK);
3604 scratch_class->set_fieldinfo_stream(new_fis);
3605 MetadataFactory::free_array<u1>(scratch_class->class_loader_data(), old_stream);
3606
3607 Array<u1>* old_table = scratch_class->fieldinfo_search_table();
3608 Array<u1>* search_table = FieldInfoStream::create_search_table(scratch_class->constants(), new_fis, scratch_class->class_loader_data(), CHECK);
3609 scratch_class->set_fieldinfo_search_table(search_table);
3610 MetadataFactory::free_array<u1>(scratch_class->class_loader_data(), old_table);
3611
3612 DEBUG_ONLY(FieldInfoStream::validate_search_table(scratch_class->constants(), new_fis, search_table));
3613 }
3614
3615 // Update constant pool indices in the inner classes info to use
3616 // new constant indices as needed. The inner classes info is a
3617 // quadruple:
3618 // (inner_class_info, outer_class_info, inner_name, inner_access_flags)
3619 InnerClassesIterator iter(scratch_class);
3620 for (; !iter.done(); iter.next()) {
3621 int cur_index = iter.inner_class_info_index();
3622 if (cur_index == 0) {
3623 continue; // JVM spec. allows null inner class refs so skip it
3624 }
3625 u2 new_index = find_new_index(cur_index);
3626 if (new_index != 0) {
3627 log_trace(redefine, class, constantpool)("inner_class_info change: %d to %d", cur_index, new_index);
3628 iter.set_inner_class_info_index(new_index);
3629 }
3630 cur_index = iter.outer_class_info_index();
3631 new_index = find_new_index(cur_index);
3632 if (new_index != 0) {
3633 log_trace(redefine, class, constantpool)("outer_class_info change: %d to %d", cur_index, new_index);
3634 iter.set_outer_class_info_index(new_index);
3635 }
3636 cur_index = iter.inner_name_index();
3637 new_index = find_new_index(cur_index);
3638 if (new_index != 0) {
3639 log_trace(redefine, class, constantpool)("inner_name change: %d to %d", cur_index, new_index);
3640 iter.set_inner_name_index(new_index);
3641 }
3642 } // end for each inner class
3643
3644 // Attach each method in klass to the new constant pool and update
3645 // to use new constant pool indices as needed:
3646 Array<Method*>* methods = scratch_class->methods();
3647 for (i = methods->length() - 1; i >= 0; i--) {
3648 methodHandle method(THREAD, methods->at(i));
3649 method->set_constants(scratch_cp());
3650
3651 u2 new_index = find_new_index(method->name_index());
3652 if (new_index != 0) {
3653 log_trace(redefine, class, constantpool)
3654 ("method-name_index change: %d to %d", method->name_index(), new_index);
3655 method->set_name_index(new_index);
3656 }
3657 new_index = find_new_index(method->signature_index());
3658 if (new_index != 0) {
3659 log_trace(redefine, class, constantpool)
3660 ("method-signature_index change: %d to %d", method->signature_index(), new_index);
3661 method->set_signature_index(new_index);
3662 }
3663 new_index = find_new_index(method->generic_signature_index());
3664 if (new_index != 0) {
3665 log_trace(redefine, class, constantpool)
3666 ("method-generic_signature_index change: %d to %d", method->generic_signature_index(), new_index);
3667 method->constMethod()->set_generic_signature_index(new_index);
3668 }
3669
3670 // Update constant pool indices in the method's checked exception
3671 // table to use new constant indices as needed.
3672 int cext_length = method->checked_exceptions_length();
3673 if (cext_length > 0) {
3674 CheckedExceptionElement * cext_table =
3675 method->checked_exceptions_start();
3676 for (int j = 0; j < cext_length; j++) {
3677 int cur_index = cext_table[j].class_cp_index;
3678 int new_index = find_new_index(cur_index);
3679 if (new_index != 0) {
3680 log_trace(redefine, class, constantpool)("cext-class_cp_index change: %d to %d", cur_index, new_index);
3681 cext_table[j].class_cp_index = (u2)new_index;
3682 }
3683 } // end for each checked exception table entry
3684 } // end if there are checked exception table entries
3685
3686 // Update each catch type index in the method's exception table
3687 // to use new constant pool indices as needed. The exception table
3688 // holds quadruple entries of the form:
3689 // (beg_bci, end_bci, handler_bci, klass_index)
3690
3691 ExceptionTable ex_table(method());
3692 int ext_length = ex_table.length();
3693
3694 for (int j = 0; j < ext_length; j ++) {
3695 int cur_index = ex_table.catch_type_index(j);
3696 u2 new_index = find_new_index(cur_index);
3697 if (new_index != 0) {
3698 log_trace(redefine, class, constantpool)("ext-klass_index change: %d to %d", cur_index, new_index);
3699 ex_table.set_catch_type_index(j, new_index);
3700 }
3701 } // end for each exception table entry
3702
3703 // Update constant pool indices in the method's local variable
3704 // table to use new constant indices as needed. The local variable
3705 // table hold sextuple entries of the form:
3706 // (start_pc, length, name_index, descriptor_index, signature_index, slot)
3707 int lvt_length = method->localvariable_table_length();
3708 if (lvt_length > 0) {
3709 LocalVariableTableElement * lv_table =
3710 method->localvariable_table_start();
3711 for (int j = 0; j < lvt_length; j++) {
3712 int cur_index = lv_table[j].name_cp_index;
3713 int new_index = find_new_index(cur_index);
3714 if (new_index != 0) {
3715 log_trace(redefine, class, constantpool)("lvt-name_cp_index change: %d to %d", cur_index, new_index);
3716 lv_table[j].name_cp_index = (u2)new_index;
3717 }
3718 cur_index = lv_table[j].descriptor_cp_index;
3719 new_index = find_new_index(cur_index);
3720 if (new_index != 0) {
3721 log_trace(redefine, class, constantpool)("lvt-descriptor_cp_index change: %d to %d", cur_index, new_index);
3722 lv_table[j].descriptor_cp_index = (u2)new_index;
3723 }
3724 cur_index = lv_table[j].signature_cp_index;
3725 new_index = find_new_index(cur_index);
3726 if (new_index != 0) {
3727 log_trace(redefine, class, constantpool)("lvt-signature_cp_index change: %d to %d", cur_index, new_index);
3728 lv_table[j].signature_cp_index = (u2)new_index;
3729 }
3730 } // end for each local variable table entry
3731 } // end if there are local variable table entries
3732
3733 // Update constant pool indices in the method's method_parameters.
3734 int mp_length = method->method_parameters_length();
3735 if (mp_length > 0) {
3736 MethodParametersElement* elem = method->method_parameters_start();
3737 for (int j = 0; j < mp_length; j++) {
3738 const int cp_index = elem[j].name_cp_index;
3739 const int new_cp_index = find_new_index(cp_index);
3740 if (new_cp_index != 0) {
3741 elem[j].name_cp_index = (u2)new_cp_index;
3742 }
3743 }
3744 }
3745
3746 rewrite_cp_refs_in_stack_map_table(method);
3747 } // end for each method
3748 } // end set_new_constant_pool()
3749
3750
3751 // Unevolving classes may point to methods of the_class directly
3752 // from their constant pool caches, itables, and/or vtables. We
3753 // use the ClassLoaderDataGraph::classes_do() facility and this helper
3754 // to fix up these pointers. MethodData also points to old methods and
3755 // must be cleaned.
3756
3757 // Adjust cpools and vtables closure
3758 void VM_RedefineClasses::AdjustAndCleanMetadata::do_klass(Klass* k) {
3759
3760 // This is a very busy routine. We don't want too much tracing
3761 // printed out.
3762 bool trace_name_printed = false;
3763
3764 // If the class being redefined is java.lang.Object, we need to fix all
3765 // array class vtables also. The _has_redefined_Object flag is global.
3766 // Once the java.lang.Object has been redefined (by the current or one
3767 // of the previous VM_RedefineClasses operations) we have to always
3768 // adjust method entries for array classes.
3769 if (k->is_array_klass() && _has_redefined_Object) {
3770 k->vtable().adjust_method_entries(&trace_name_printed);
3771
3772 } else if (k->is_instance_klass()) {
3773 HandleMark hm(_thread);
3774 InstanceKlass *ik = InstanceKlass::cast(k);
3775
3776 // Clean MethodData of this class's methods so they don't refer to
3777 // old methods that are no longer running.
3778 Array<Method*>* methods = ik->methods();
3779 int num_methods = methods->length();
3780 for (int index = 0; index < num_methods; ++index) {
3781 if (methods->at(index)->method_data() != nullptr) {
3782 methods->at(index)->method_data()->clean_weak_method_links();
3783 }
3784 }
3785
3786 // Adjust all vtables, default methods and itables, to clean out old methods.
3787 ResourceMark rm(_thread);
3788 if (ik->vtable_length() > 0) {
3789 ik->vtable().adjust_method_entries(&trace_name_printed);
3790 ik->adjust_default_methods(&trace_name_printed);
3791 }
3792
3793 if (ik->itable_length() > 0) {
3794 ik->itable().adjust_method_entries(&trace_name_printed);
3795 }
3796
3797 // The constant pools in other classes (other_cp) can refer to
3798 // old methods. We have to update method information in
3799 // other_cp's cache. If other_cp has a previous version, then we
3800 // have to repeat the process for each previous version. The
3801 // constant pool cache holds the Method*s for non-virtual
3802 // methods and for virtual, final methods.
3803 //
3804 // Special case: if the current class is being redefined by the current
3805 // VM_RedefineClasses operation, then new_cp has already been attached
3806 // to the_class and old_cp has already been added as a previous version.
3807 // The new_cp doesn't have any cached references to old methods so it
3808 // doesn't need to be updated and we could optimize by skipping it.
3809 // However, the current class can be marked as being redefined by another
3810 // VM_RedefineClasses operation which has already executed its doit_prologue
3811 // and needs cpcache method entries adjusted. For simplicity, the cpcache
3812 // update is done unconditionally. It should result in doing nothing for
3813 // classes being redefined by the current VM_RedefineClasses operation.
3814 // Method entries in the previous version(s) are adjusted as well.
3815 ConstantPoolCache* cp_cache;
3816
3817 // this klass' constant pool cache may need adjustment
3818 ConstantPool* other_cp = ik->constants();
3819 cp_cache = other_cp->cache();
3820 if (cp_cache != nullptr) {
3821 cp_cache->adjust_method_entries(&trace_name_printed);
3822 }
3823
3824 // the previous versions' constant pool caches may need adjustment
3825 for (InstanceKlass* pv_node = ik->previous_versions();
3826 pv_node != nullptr;
3827 pv_node = pv_node->previous_versions()) {
3828 cp_cache = pv_node->constants()->cache();
3829 if (cp_cache != nullptr) {
3830 cp_cache->adjust_method_entries(&trace_name_printed);
3831 }
3832 }
3833 }
3834 }
3835
3836 void VM_RedefineClasses::update_jmethod_ids() {
3837 for (int j = 0; j < _matching_methods_length; ++j) {
3838 Method* old_method = _matching_old_methods[j];
3839 // The method_idnum should be within the range of 1..number-of-methods
3840 // until incremented later for obsolete methods.
3841 // The increment is so if a jmethodID is created for an old obsolete method
3842 // it gets a new jmethodID cache slot in the InstanceKlass.
3843 // They're cleaned out later when all methods of the previous version are purged.
3844 assert(old_method->method_idnum() <= _old_methods->length(),
3845 "shouldn't be incremented yet for obsolete methods");
3846 jmethodID jmid = old_method->find_jmethod_id_or_null();
3847 if (jmid != nullptr) {
3848 // There is a jmethodID, change it to point to the new method
3849 Method* new_method = _matching_new_methods[j];
3850 Method::change_method_associated_with_jmethod_id(jmid, new_method);
3851 assert(Method::resolve_jmethod_id(jmid) == _matching_new_methods[j],
3852 "should be replaced");
3853 }
3854 }
3855 }
3856
3857 int VM_RedefineClasses::check_methods_and_mark_as_obsolete() {
3858 int emcp_method_count = 0;
3859 int obsolete_count = 0;
3860 int old_index = 0;
3861 for (int j = 0; j < _matching_methods_length; ++j, ++old_index) {
3862 Method* old_method = _matching_old_methods[j];
3863 Method* new_method = _matching_new_methods[j];
3864 Method* old_array_method;
3865
3866 // Maintain an old_index into the _old_methods array by skipping
3867 // deleted methods
3868 while ((old_array_method = _old_methods->at(old_index)) != old_method) {
3869 ++old_index;
3870 }
3871
3872 if (MethodComparator::methods_EMCP(old_method, new_method)) {
3873 // The EMCP definition from JSR-163 requires the bytecodes to be
3874 // the same with the exception of constant pool indices which may
3875 // differ. However, the constants referred to by those indices
3876 // must be the same.
3877 //
3878 // We use methods_EMCP() for comparison since constant pool
3879 // merging can remove duplicate constant pool entries that were
3880 // present in the old method and removed from the rewritten new
3881 // method. A faster binary comparison function would consider the
3882 // old and new methods to be different when they are actually
3883 // EMCP.
3884 //
3885 // The old and new methods are EMCP and you would think that we
3886 // could get rid of one of them here and now and save some space.
3887 // However, the concept of EMCP only considers the bytecodes and
3888 // the constant pool entries in the comparison. Other things,
3889 // e.g., the line number table (LNT) or the local variable table
3890 // (LVT) don't count in the comparison. So the new (and EMCP)
3891 // method can have a new LNT that we need so we can't just
3892 // overwrite the new method with the old method.
3893 //
3894 // When this routine is called, we have already attached the new
3895 // methods to the_class so the old methods are effectively
3896 // overwritten. However, if an old method is still executing,
3897 // then the old method cannot be collected until sometime after
3898 // the old method call has returned. So the overwriting of old
3899 // methods by new methods will save us space except for those
3900 // (hopefully few) old methods that are still executing.
3901 //
3902 // A method refers to a ConstMethod* and this presents another
3903 // possible avenue to space savings. The ConstMethod* in the
3904 // new method contains possibly new attributes (LNT, LVT, etc).
3905 // At first glance, it seems possible to save space by replacing
3906 // the ConstMethod* in the old method with the ConstMethod*
3907 // from the new method. The old and new methods would share the
3908 // same ConstMethod* and we would save the space occupied by
3909 // the old ConstMethod*. However, the ConstMethod* contains
3910 // a back reference to the containing method. Sharing the
3911 // ConstMethod* between two methods could lead to confusion in
3912 // the code that uses the back reference. This would lead to
3913 // brittle code that could be broken in non-obvious ways now or
3914 // in the future.
3915 //
3916 // Another possibility is to copy the ConstMethod* from the new
3917 // method to the old method and then overwrite the new method with
3918 // the old method. Since the ConstMethod* contains the bytecodes
3919 // for the method embedded in the oop, this option would change
3920 // the bytecodes out from under any threads executing the old
3921 // method and make the thread's bcp invalid. Since EMCP requires
3922 // that the bytecodes be the same modulo constant pool indices, it
3923 // is straight forward to compute the correct new bcp in the new
3924 // ConstMethod* from the old bcp in the old ConstMethod*. The
3925 // time consuming part would be searching all the frames in all
3926 // of the threads to find all of the calls to the old method.
3927 //
3928 // It looks like we will have to live with the limited savings
3929 // that we get from effectively overwriting the old methods
3930 // when the new methods are attached to the_class.
3931
3932 // Count number of methods that are EMCP. The method will be marked
3933 // old but not obsolete if it is EMCP.
3934 emcp_method_count++;
3935
3936 // An EMCP method is _not_ obsolete. An obsolete method has a
3937 // different jmethodID than the current method. An EMCP method
3938 // has the same jmethodID as the current method. Having the
3939 // same jmethodID for all EMCP versions of a method allows for
3940 // a consistent view of the EMCP methods regardless of which
3941 // EMCP method you happen to have in hand. For example, a
3942 // breakpoint set in one EMCP method will work for all EMCP
3943 // versions of the method including the current one.
3944 } else {
3945 // mark obsolete methods as such
3946 old_method->set_is_obsolete();
3947 obsolete_count++;
3948
3949 // obsolete methods need a unique idnum so they become new entries in
3950 // the jmethodID cache in InstanceKlass
3951 assert(old_method->method_idnum() == new_method->method_idnum(), "must match");
3952 u2 num = InstanceKlass::cast(_the_class)->next_method_idnum();
3953 if (num != ConstMethod::UNSET_IDNUM) {
3954 old_method->set_method_idnum(num);
3955 }
3956
3957 // With tracing we try not to "yack" too much. The position of
3958 // this trace assumes there are fewer obsolete methods than
3959 // EMCP methods.
3960 if (log_is_enabled(Trace, redefine, class, obsolete, mark)) {
3961 ResourceMark rm;
3962 log_trace(redefine, class, obsolete, mark)
3963 ("mark %s(%s) as obsolete", old_method->name()->as_C_string(), old_method->signature()->as_C_string());
3964 }
3965 }
3966 old_method->set_is_old();
3967 }
3968 for (int i = 0; i < _deleted_methods_length; ++i) {
3969 Method* old_method = _deleted_methods[i];
3970
3971 assert(!old_method->has_vtable_index(),
3972 "cannot delete methods with vtable entries");;
3973
3974 // Mark all deleted methods as old, obsolete and deleted
3975 old_method->set_is_deleted();
3976 old_method->set_is_old();
3977 old_method->set_is_obsolete();
3978 ++obsolete_count;
3979 // With tracing we try not to "yack" too much. The position of
3980 // this trace assumes there are fewer obsolete methods than
3981 // EMCP methods.
3982 if (log_is_enabled(Trace, redefine, class, obsolete, mark)) {
3983 ResourceMark rm;
3984 log_trace(redefine, class, obsolete, mark)
3985 ("mark deleted %s(%s) as obsolete", old_method->name()->as_C_string(), old_method->signature()->as_C_string());
3986 }
3987 }
3988 assert((emcp_method_count + obsolete_count) == _old_methods->length(),
3989 "sanity check");
3990 log_trace(redefine, class, obsolete, mark)("EMCP_cnt=%d, obsolete_cnt=%d", emcp_method_count, obsolete_count);
3991 return emcp_method_count;
3992 }
3993
3994 // This internal class transfers the native function registration from old methods
3995 // to new methods. It is designed to handle both the simple case of unchanged
3996 // native methods and the complex cases of native method prefixes being added and/or
3997 // removed.
3998 // It expects only to be used during the VM_RedefineClasses op (a safepoint).
3999 //
4000 // This class is used after the new methods have been installed in "the_class".
4001 //
4002 // So, for example, the following must be handled. Where 'm' is a method and
4003 // a number followed by an underscore is a prefix.
4004 //
4005 // Old Name New Name
4006 // Simple transfer to new method m -> m
4007 // Add prefix m -> 1_m
4008 // Remove prefix 1_m -> m
4009 // Simultaneous add of prefixes m -> 3_2_1_m
4010 // Simultaneous removal of prefixes 3_2_1_m -> m
4011 // Simultaneous add and remove 1_m -> 2_m
4012 // Same, caused by prefix removal only 3_2_1_m -> 3_2_m
4013 //
4014 class TransferNativeFunctionRegistration {
4015 private:
4016 InstanceKlass* the_class;
4017 int prefix_count;
4018 char** prefixes;
4019
4020 // Recursively search the binary tree of possibly prefixed method names.
4021 // Iteration could be used if all agents were well behaved. Full tree walk is
4022 // more resilent to agents not cleaning up intermediate methods.
4023 // Branch at each depth in the binary tree is:
4024 // (1) without the prefix.
4025 // (2) with the prefix.
4026 // where 'prefix' is the prefix at that 'depth' (first prefix, second prefix,...)
4027 Method* search_prefix_name_space(int depth, char* name_str, size_t name_len,
4028 Symbol* signature) {
4029 TempNewSymbol name_symbol = SymbolTable::probe(name_str, (int)name_len);
4030 if (name_symbol != nullptr) {
4031 Method* method = the_class->lookup_method(name_symbol, signature);
4032 if (method != nullptr) {
4033 // Even if prefixed, intermediate methods must exist.
4034 if (method->is_native()) {
4035 // Wahoo, we found a (possibly prefixed) version of the method, return it.
4036 return method;
4037 }
4038 if (depth < prefix_count) {
4039 // Try applying further prefixes (other than this one).
4040 method = search_prefix_name_space(depth+1, name_str, name_len, signature);
4041 if (method != nullptr) {
4042 return method; // found
4043 }
4044
4045 // Try adding this prefix to the method name and see if it matches
4046 // another method name.
4047 char* prefix = prefixes[depth];
4048 size_t prefix_len = strlen(prefix);
4049 size_t trial_len = name_len + prefix_len;
4050 char* trial_name_str = NEW_RESOURCE_ARRAY(char, trial_len + 1);
4051 strcpy(trial_name_str, prefix);
4052 strcat(trial_name_str, name_str);
4053 method = search_prefix_name_space(depth+1, trial_name_str, trial_len,
4054 signature);
4055 if (method != nullptr) {
4056 // If found along this branch, it was prefixed, mark as such
4057 method->set_is_prefixed_native();
4058 return method; // found
4059 }
4060 }
4061 }
4062 }
4063 return nullptr; // This whole branch bore nothing
4064 }
4065
4066 // Return the method name with old prefixes stripped away.
4067 char* method_name_without_prefixes(Method* method) {
4068 Symbol* name = method->name();
4069 char* name_str = name->as_utf8();
4070
4071 // Old prefixing may be defunct, strip prefixes, if any.
4072 for (int i = prefix_count-1; i >= 0; i--) {
4073 char* prefix = prefixes[i];
4074 size_t prefix_len = strlen(prefix);
4075 if (strncmp(prefix, name_str, prefix_len) == 0) {
4076 name_str += prefix_len;
4077 }
4078 }
4079 return name_str;
4080 }
4081
4082 // Strip any prefixes off the old native method, then try to find a
4083 // (possibly prefixed) new native that matches it.
4084 Method* strip_and_search_for_new_native(Method* method) {
4085 ResourceMark rm;
4086 char* name_str = method_name_without_prefixes(method);
4087 return search_prefix_name_space(0, name_str, strlen(name_str),
4088 method->signature());
4089 }
4090
4091 public:
4092
4093 // Construct a native method transfer processor for this class.
4094 TransferNativeFunctionRegistration(InstanceKlass* _the_class) {
4095 assert(SafepointSynchronize::is_at_safepoint(), "sanity check");
4096
4097 the_class = _the_class;
4098 prefixes = JvmtiExport::get_all_native_method_prefixes(&prefix_count);
4099 }
4100
4101 // Attempt to transfer any of the old or deleted methods that are native
4102 void transfer_registrations(Method** old_methods, int methods_length) {
4103 for (int j = 0; j < methods_length; j++) {
4104 Method* old_method = old_methods[j];
4105
4106 if (old_method->is_native() && old_method->has_native_function()) {
4107 Method* new_method = strip_and_search_for_new_native(old_method);
4108 if (new_method != nullptr) {
4109 // Actually set the native function in the new method.
4110 // Redefine does not send events (except CFLH), certainly not this
4111 // behind the scenes re-registration.
4112 new_method->set_native_function(old_method->native_function(),
4113 !Method::native_bind_event_is_interesting);
4114 }
4115 }
4116 }
4117 }
4118 };
4119
4120 // Don't lose the association between a native method and its JNI function.
4121 void VM_RedefineClasses::transfer_old_native_function_registrations(InstanceKlass* the_class) {
4122 TransferNativeFunctionRegistration transfer(the_class);
4123 transfer.transfer_registrations(_deleted_methods, _deleted_methods_length);
4124 transfer.transfer_registrations(_matching_old_methods, _matching_methods_length);
4125 }
4126
4127 // Deoptimize all compiled code that depends on the classes redefined.
4128 //
4129 // If the can_redefine_classes capability is obtained in the onload
4130 // phase or 'AlwaysRecordEvolDependencies' is true, then the compiler has
4131 // recorded all dependencies from startup. In that case we need only
4132 // deoptimize and throw away all compiled code that depends on the class.
4133 //
4134 // If can_redefine_classes is obtained sometime after the onload phase
4135 // (and 'AlwaysRecordEvolDependencies' is false) then the dependency
4136 // information may be incomplete. In that case the first call to
4137 // RedefineClasses causes all compiled code to be thrown away. As
4138 // can_redefine_classes has been obtained then all future compilations will
4139 // record dependencies so second and subsequent calls to RedefineClasses
4140 // need only throw away code that depends on the class.
4141 //
4142
4143 void VM_RedefineClasses::flush_dependent_code() {
4144 assert(SafepointSynchronize::is_at_safepoint(), "sanity check");
4145 assert(JvmtiExport::all_dependencies_are_recorded() || !AlwaysRecordEvolDependencies, "sanity check");
4146
4147 DeoptimizationScope deopt_scope;
4148
4149 // This is the first redefinition, mark all the nmethods for deoptimization
4150 if (!JvmtiExport::all_dependencies_are_recorded()) {
4151 CodeCache::mark_all_nmethods_for_evol_deoptimization(&deopt_scope);
4152 log_debug(redefine, class, nmethod)("Marked all nmethods for deopt");
4153 } else {
4154 CodeCache::mark_dependents_for_evol_deoptimization(&deopt_scope);
4155 log_debug(redefine, class, nmethod)("Marked dependent nmethods for deopt");
4156 }
4157
4158 deopt_scope.deoptimize_marked();
4159
4160 // From now on we know that the dependency information is complete
4161 JvmtiExport::set_all_dependencies_are_recorded(true);
4162 }
4163
4164 void VM_RedefineClasses::compute_added_deleted_matching_methods() {
4165 Method* old_method;
4166 Method* new_method;
4167
4168 _matching_old_methods = NEW_RESOURCE_ARRAY(Method*, _old_methods->length());
4169 _matching_new_methods = NEW_RESOURCE_ARRAY(Method*, _old_methods->length());
4170 _added_methods = NEW_RESOURCE_ARRAY(Method*, _new_methods->length());
4171 _deleted_methods = NEW_RESOURCE_ARRAY(Method*, _old_methods->length());
4172
4173 _matching_methods_length = 0;
4174 _deleted_methods_length = 0;
4175 _added_methods_length = 0;
4176
4177 int nj = 0;
4178 int oj = 0;
4179 while (true) {
4180 if (oj >= _old_methods->length()) {
4181 if (nj >= _new_methods->length()) {
4182 break; // we've looked at everything, done
4183 }
4184 // New method at the end
4185 new_method = _new_methods->at(nj);
4186 _added_methods[_added_methods_length++] = new_method;
4187 ++nj;
4188 } else if (nj >= _new_methods->length()) {
4189 // Old method, at the end, is deleted
4190 old_method = _old_methods->at(oj);
4191 _deleted_methods[_deleted_methods_length++] = old_method;
4192 ++oj;
4193 } else {
4194 old_method = _old_methods->at(oj);
4195 new_method = _new_methods->at(nj);
4196 if (old_method->name() == new_method->name()) {
4197 if (old_method->signature() == new_method->signature()) {
4198 _matching_old_methods[_matching_methods_length ] = old_method;
4199 _matching_new_methods[_matching_methods_length++] = new_method;
4200 ++nj;
4201 ++oj;
4202 } else {
4203 // added overloaded have already been moved to the end,
4204 // so this is a deleted overloaded method
4205 _deleted_methods[_deleted_methods_length++] = old_method;
4206 ++oj;
4207 }
4208 } else { // names don't match
4209 if (old_method->name()->fast_compare(new_method->name()) > 0) {
4210 // new method
4211 _added_methods[_added_methods_length++] = new_method;
4212 ++nj;
4213 } else {
4214 // deleted method
4215 _deleted_methods[_deleted_methods_length++] = old_method;
4216 ++oj;
4217 }
4218 }
4219 }
4220 }
4221 assert(_matching_methods_length + _deleted_methods_length == _old_methods->length(), "sanity");
4222 assert(_matching_methods_length + _added_methods_length == _new_methods->length(), "sanity");
4223 }
4224
4225
4226 void VM_RedefineClasses::swap_annotations(InstanceKlass* the_class,
4227 InstanceKlass* scratch_class) {
4228 // Swap annotation fields values
4229 Annotations* old_annotations = the_class->annotations();
4230 the_class->set_annotations(scratch_class->annotations());
4231 scratch_class->set_annotations(old_annotations);
4232 }
4233
4234
4235 // Install the redefinition of a class:
4236 // - house keeping (flushing breakpoints and caches, deoptimizing
4237 // dependent compiled code)
4238 // - replacing parts in the_class with parts from scratch_class
4239 // - adding a weak reference to track the obsolete but interesting
4240 // parts of the_class
4241 // - adjusting constant pool caches and vtables in other classes
4242 // that refer to methods in the_class. These adjustments use the
4243 // ClassLoaderDataGraph::classes_do() facility which only allows
4244 // a helper method to be specified. The interesting parameters
4245 // that we would like to pass to the helper method are saved in
4246 // static global fields in the VM operation.
4247 void VM_RedefineClasses::redefine_single_class(Thread* current, jclass the_jclass,
4248 InstanceKlass* scratch_class) {
4249
4250 HandleMark hm(current); // make sure handles from this call are freed
4251
4252 if (log_is_enabled(Info, redefine, class, timer)) {
4253 _timer_rsc_phase1.start();
4254 }
4255
4256 InstanceKlass* the_class = get_ik(the_jclass);
4257
4258 // Set a flag to control and optimize adjusting method entries
4259 _has_redefined_Object |= the_class == vmClasses::Object_klass();
4260
4261 // Remove all breakpoints in methods of this class
4262 JvmtiBreakpoints& jvmti_breakpoints = JvmtiCurrentBreakpoints::get_jvmti_breakpoints();
4263 jvmti_breakpoints.clearall_in_class_at_safepoint(the_class);
4264
4265 _old_methods = the_class->methods();
4266 _new_methods = scratch_class->methods();
4267 _the_class = the_class;
4268 compute_added_deleted_matching_methods();
4269 update_jmethod_ids();
4270
4271 _any_class_has_resolved_methods = the_class->has_resolved_methods() || _any_class_has_resolved_methods;
4272
4273 // Attach new constant pool to the original klass. The original
4274 // klass still refers to the old constant pool (for now).
4275 scratch_class->constants()->set_pool_holder(the_class);
4276
4277 #if 0
4278 // In theory, with constant pool merging in place we should be able
4279 // to save space by using the new, merged constant pool in place of
4280 // the old constant pool(s). By "pool(s)" I mean the constant pool in
4281 // the klass version we are replacing now and any constant pool(s) in
4282 // previous versions of klass. Nice theory, doesn't work in practice.
4283 // When this code is enabled, even simple programs throw NullPointer
4284 // exceptions. I'm guessing that this is caused by some constant pool
4285 // cache difference between the new, merged constant pool and the
4286 // constant pool that was just being used by the klass. I'm keeping
4287 // this code around to archive the idea, but the code has to remain
4288 // disabled for now.
4289
4290 // Attach each old method to the new constant pool. This can be
4291 // done here since we are past the bytecode verification and
4292 // constant pool optimization phases.
4293 for (int i = _old_methods->length() - 1; i >= 0; i--) {
4294 Method* method = _old_methods->at(i);
4295 method->set_constants(scratch_class->constants());
4296 }
4297
4298 // NOTE: this doesn't work because you can redefine the same class in two
4299 // threads, each getting their own constant pool data appended to the
4300 // original constant pool. In order for the new methods to work when they
4301 // become old methods, they need to keep their updated copy of the constant pool.
4302
4303 {
4304 // walk all previous versions of the klass
4305 InstanceKlass *ik = the_class;
4306 PreviousVersionWalker pvw(ik);
4307 do {
4308 ik = pvw.next_previous_version();
4309 if (ik != nullptr) {
4310
4311 // attach previous version of klass to the new constant pool
4312 ik->set_constants(scratch_class->constants());
4313
4314 // Attach each method in the previous version of klass to the
4315 // new constant pool
4316 Array<Method*>* prev_methods = ik->methods();
4317 for (int i = prev_methods->length() - 1; i >= 0; i--) {
4318 Method* method = prev_methods->at(i);
4319 method->set_constants(scratch_class->constants());
4320 }
4321 }
4322 } while (ik != nullptr);
4323 }
4324 #endif
4325
4326 // Replace methods and constantpool
4327 the_class->set_methods(_new_methods);
4328 scratch_class->set_methods(_old_methods); // To prevent potential GCing of the old methods,
4329 // and to be able to undo operation easily.
4330
4331 Array<int>* old_ordering = the_class->method_ordering();
4332 the_class->set_method_ordering(scratch_class->method_ordering());
4333 scratch_class->set_method_ordering(old_ordering);
4334
4335 ConstantPool* old_constants = the_class->constants();
4336 the_class->set_constants(scratch_class->constants());
4337 scratch_class->set_constants(old_constants); // See the previous comment.
4338 #if 0
4339 // We are swapping the guts of "the new class" with the guts of "the
4340 // class". Since the old constant pool has just been attached to "the
4341 // new class", it seems logical to set the pool holder in the old
4342 // constant pool also. However, doing this will change the observable
4343 // class hierarchy for any old methods that are still executing. A
4344 // method can query the identity of its "holder" and this query uses
4345 // the method's constant pool link to find the holder. The change in
4346 // holding class from "the class" to "the new class" can confuse
4347 // things.
4348 //
4349 // Setting the old constant pool's holder will also cause
4350 // verification done during vtable initialization below to fail.
4351 // During vtable initialization, the vtable's class is verified to be
4352 // a subtype of the method's holder. The vtable's class is "the
4353 // class" and the method's holder is gotten from the constant pool
4354 // link in the method itself. For "the class"'s directly implemented
4355 // methods, the method holder is "the class" itself (as gotten from
4356 // the new constant pool). The check works fine in this case. The
4357 // check also works fine for methods inherited from super classes.
4358 //
4359 // Miranda methods are a little more complicated. A miranda method is
4360 // provided by an interface when the class implementing the interface
4361 // does not provide its own method. These interfaces are implemented
4362 // internally as an InstanceKlass. These special instanceKlasses
4363 // share the constant pool of the class that "implements" the
4364 // interface. By sharing the constant pool, the method holder of a
4365 // miranda method is the class that "implements" the interface. In a
4366 // non-redefine situation, the subtype check works fine. However, if
4367 // the old constant pool's pool holder is modified, then the check
4368 // fails because there is no class hierarchy relationship between the
4369 // vtable's class and "the new class".
4370
4371 old_constants->set_pool_holder(scratch_class());
4372 #endif
4373
4374 // track number of methods that are EMCP for add_previous_version() call below
4375 int emcp_method_count = check_methods_and_mark_as_obsolete();
4376 transfer_old_native_function_registrations(the_class);
4377
4378 if (scratch_class->get_cached_class_file() != the_class->get_cached_class_file()) {
4379 // 1. the_class doesn't have a cache yet, scratch_class does have a cache.
4380 // 2. The same class can be present twice in the scratch classes list or there
4381 // are multiple concurrent RetransformClasses calls on different threads.
4382 // the_class and scratch_class have the same cached bytes, but different buffers.
4383 // In such cases we need to deallocate one of the buffers.
4384 // 3. RedefineClasses and the_class has cached bytes from a previous transformation.
4385 // In the case we need to use class bytes from scratch_class.
4386 if (the_class->get_cached_class_file() != nullptr) {
4387 os::free(the_class->get_cached_class_file());
4388 }
4389 the_class->set_cached_class_file(scratch_class->get_cached_class_file());
4390 }
4391
4392 // null out in scratch class to not delete twice. The class to be redefined
4393 // always owns these bytes.
4394 scratch_class->set_cached_class_file(nullptr);
4395
4396 // Replace inner_classes
4397 Array<u2>* old_inner_classes = the_class->inner_classes();
4398 the_class->set_inner_classes(scratch_class->inner_classes());
4399 scratch_class->set_inner_classes(old_inner_classes);
4400
4401 // Initialize the vtable and interface table after
4402 // methods have been rewritten
4403 // no exception should happen here since we explicitly
4404 // do not check loader constraints.
4405 // compare_and_normalize_class_versions has already checked:
4406 // - classloaders unchanged, signatures unchanged
4407 // - all instanceKlasses for redefined classes reused & contents updated
4408 the_class->vtable().initialize_vtable();
4409 the_class->itable().initialize_itable();
4410
4411 // Update jmethodID cache if present.
4412 the_class->update_methods_jmethod_cache();
4413
4414 // Copy the "source debug extension" attribute from new class version
4415 the_class->set_source_debug_extension(
4416 scratch_class->source_debug_extension(),
4417 scratch_class->source_debug_extension() == nullptr ? 0 :
4418 (int)strlen(scratch_class->source_debug_extension()));
4419
4420 // Use of javac -g could be different in the old and the new
4421 if (scratch_class->has_localvariable_table() !=
4422 the_class->has_localvariable_table()) {
4423 the_class->set_has_localvariable_table(scratch_class->has_localvariable_table());
4424 }
4425
4426 swap_annotations(the_class, scratch_class);
4427
4428 // Replace minor version number of class file
4429 u2 old_minor_version = the_class->constants()->minor_version();
4430 the_class->constants()->set_minor_version(scratch_class->constants()->minor_version());
4431 scratch_class->constants()->set_minor_version(old_minor_version);
4432
4433 // Replace major version number of class file
4434 u2 old_major_version = the_class->constants()->major_version();
4435 the_class->constants()->set_major_version(scratch_class->constants()->major_version());
4436 scratch_class->constants()->set_major_version(old_major_version);
4437
4438 // Replace CP indexes for class and name+type of enclosing method
4439 u2 old_class_idx = the_class->enclosing_method_class_index();
4440 u2 old_method_idx = the_class->enclosing_method_method_index();
4441 the_class->set_enclosing_method_indices(
4442 scratch_class->enclosing_method_class_index(),
4443 scratch_class->enclosing_method_method_index());
4444 scratch_class->set_enclosing_method_indices(old_class_idx, old_method_idx);
4445
4446 if (!the_class->has_been_redefined()) {
4447 the_class->set_has_been_redefined();
4448 }
4449
4450 // Scratch class is unloaded but still needs cleaning, and skipping for CDS.
4451 scratch_class->set_is_scratch_class();
4452
4453 // keep track of previous versions of this class
4454 the_class->add_previous_version(scratch_class, emcp_method_count);
4455
4456 JFR_ONLY(Jfr::on_klass_redefinition(the_class, scratch_class);)
4457
4458 _timer_rsc_phase1.stop();
4459 if (log_is_enabled(Info, redefine, class, timer)) {
4460 _timer_rsc_phase2.start();
4461 }
4462
4463 if (the_class->oop_map_cache() != nullptr) {
4464 // Flush references to any obsolete methods from the oop map cache
4465 // so that obsolete methods are not pinned.
4466 the_class->oop_map_cache()->flush_obsolete_entries();
4467 }
4468
4469 increment_class_counter(the_class);
4470
4471 if (EventClassRedefinition::is_enabled()) {
4472 EventClassRedefinition event;
4473 event.set_classModificationCount(java_lang_Class::classRedefinedCount(the_class->java_mirror()));
4474 event.set_redefinedClass(the_class);
4475 event.set_redefinitionId(_id);
4476 event.commit();
4477 }
4478
4479 {
4480 ResourceMark rm(current);
4481 // increment the classRedefinedCount field in the_class and in any
4482 // direct and indirect subclasses of the_class
4483 physical_memory_size_type avail_mem = 0;
4484 // Return value ignored - defaulting to 0 on failure.
4485 (void)os::available_memory(avail_mem);
4486 log_info(redefine, class, load)
4487 ("redefined name=%s, count=%d (avail_mem=" PHYS_MEM_TYPE_FORMAT "K)",
4488 the_class->external_name(), java_lang_Class::classRedefinedCount(the_class->java_mirror()), avail_mem >> 10);
4489 Events::log_redefinition(current, "redefined class name=%s, count=%d",
4490 the_class->external_name(),
4491 java_lang_Class::classRedefinedCount(the_class->java_mirror()));
4492
4493 }
4494 _timer_rsc_phase2.stop();
4495
4496 } // end redefine_single_class()
4497
4498
4499 // Increment the classRedefinedCount field in the specific InstanceKlass
4500 // and in all direct and indirect subclasses.
4501 void VM_RedefineClasses::increment_class_counter(InstanceKlass* ik) {
4502 for (ClassHierarchyIterator iter(ik); !iter.done(); iter.next()) {
4503 // Only update instanceKlasses
4504 Klass* sub = iter.klass();
4505 if (sub->is_instance_klass()) {
4506 oop class_mirror = InstanceKlass::cast(sub)->java_mirror();
4507 Klass* class_oop = java_lang_Class::as_Klass(class_mirror);
4508 int new_count = java_lang_Class::classRedefinedCount(class_mirror) + 1;
4509 java_lang_Class::set_classRedefinedCount(class_mirror, new_count);
4510
4511 if (class_oop != _the_class) {
4512 // _the_class count is printed at end of redefine_single_class()
4513 log_debug(redefine, class, subclass)("updated count in subclass=%s to %d", ik->external_name(), new_count);
4514 }
4515 }
4516 }
4517 }
4518
4519 void VM_RedefineClasses::CheckClass::do_klass(Klass* k) {
4520 bool no_old_methods = true; // be optimistic
4521
4522 // Both array and instance classes have vtables.
4523 // a vtable should never contain old or obsolete methods
4524 ResourceMark rm(_thread);
4525 if (k->vtable_length() > 0 &&
4526 !k->vtable().check_no_old_or_obsolete_entries()) {
4527 if (log_is_enabled(Trace, redefine, class, obsolete, metadata)) {
4528 log_trace(redefine, class, obsolete, metadata)
4529 ("klassVtable::check_no_old_or_obsolete_entries failure -- OLD or OBSOLETE method found -- class: %s",
4530 k->signature_name());
4531 k->vtable().dump_vtable();
4532 }
4533 no_old_methods = false;
4534 }
4535
4536 if (k->is_instance_klass()) {
4537 HandleMark hm(_thread);
4538 InstanceKlass *ik = InstanceKlass::cast(k);
4539
4540 // an itable should never contain old or obsolete methods
4541 if (ik->itable_length() > 0 &&
4542 !ik->itable().check_no_old_or_obsolete_entries()) {
4543 if (log_is_enabled(Trace, redefine, class, obsolete, metadata)) {
4544 log_trace(redefine, class, obsolete, metadata)
4545 ("klassItable::check_no_old_or_obsolete_entries failure -- OLD or OBSOLETE method found -- class: %s",
4546 ik->signature_name());
4547 ik->itable().dump_itable();
4548 }
4549 no_old_methods = false;
4550 }
4551
4552 // the constant pool cache should never contain non-deleted old or obsolete methods
4553 if (ik->constants() != nullptr &&
4554 ik->constants()->cache() != nullptr &&
4555 !ik->constants()->cache()->check_no_old_or_obsolete_entries()) {
4556 if (log_is_enabled(Trace, redefine, class, obsolete, metadata)) {
4557 log_trace(redefine, class, obsolete, metadata)
4558 ("cp-cache::check_no_old_or_obsolete_entries failure -- OLD or OBSOLETE method found -- class: %s",
4559 ik->signature_name());
4560 ik->constants()->cache()->dump_cache();
4561 }
4562 no_old_methods = false;
4563 }
4564 }
4565
4566 // print and fail guarantee if old methods are found.
4567 if (!no_old_methods) {
4568 if (log_is_enabled(Trace, redefine, class, obsolete, metadata)) {
4569 dump_methods();
4570 } else {
4571 log_trace(redefine, class)("Use the '-Xlog:redefine+class*:' option "
4572 "to see more info about the following guarantee() failure.");
4573 }
4574 guarantee(false, "OLD and/or OBSOLETE method(s) found");
4575 }
4576 }
4577
4578 u8 VM_RedefineClasses::next_id() {
4579 while (true) {
4580 u8 id = _id_counter;
4581 u8 next_id = id + 1;
4582 u8 result = AtomicAccess::cmpxchg(&_id_counter, id, next_id);
4583 if (result == id) {
4584 return next_id;
4585 }
4586 }
4587 }
4588
4589 void VM_RedefineClasses::dump_methods() {
4590 int j;
4591 log_trace(redefine, class, dump)("_old_methods --");
4592 for (j = 0; j < _old_methods->length(); ++j) {
4593 LogStreamHandle(Trace, redefine, class, dump) log_stream;
4594 Method* m = _old_methods->at(j);
4595 log_stream.print("%4d (%5d) ", j, m->vtable_index());
4596 m->access_flags().print_on(&log_stream);
4597 log_stream.print(" -- ");
4598 m->print_name(&log_stream);
4599 log_stream.cr();
4600 }
4601 log_trace(redefine, class, dump)("_new_methods --");
4602 for (j = 0; j < _new_methods->length(); ++j) {
4603 LogStreamHandle(Trace, redefine, class, dump) log_stream;
4604 Method* m = _new_methods->at(j);
4605 log_stream.print("%4d (%5d) ", j, m->vtable_index());
4606 m->access_flags().print_on(&log_stream);
4607 log_stream.print(" -- ");
4608 m->print_name(&log_stream);
4609 log_stream.cr();
4610 }
4611 log_trace(redefine, class, dump)("_matching_methods --");
4612 for (j = 0; j < _matching_methods_length; ++j) {
4613 LogStreamHandle(Trace, redefine, class, dump) log_stream;
4614 Method* m = _matching_old_methods[j];
4615 log_stream.print("%4d (%5d) ", j, m->vtable_index());
4616 m->access_flags().print_on(&log_stream);
4617 log_stream.print(" -- ");
4618 m->print_name();
4619 log_stream.cr();
4620
4621 m = _matching_new_methods[j];
4622 log_stream.print(" (%5d) ", m->vtable_index());
4623 m->access_flags().print_on(&log_stream);
4624 log_stream.cr();
4625 }
4626 log_trace(redefine, class, dump)("_deleted_methods --");
4627 for (j = 0; j < _deleted_methods_length; ++j) {
4628 LogStreamHandle(Trace, redefine, class, dump) log_stream;
4629 Method* m = _deleted_methods[j];
4630 log_stream.print("%4d (%5d) ", j, m->vtable_index());
4631 m->access_flags().print_on(&log_stream);
4632 log_stream.print(" -- ");
4633 m->print_name(&log_stream);
4634 log_stream.cr();
4635 }
4636 log_trace(redefine, class, dump)("_added_methods --");
4637 for (j = 0; j < _added_methods_length; ++j) {
4638 LogStreamHandle(Trace, redefine, class, dump) log_stream;
4639 Method* m = _added_methods[j];
4640 log_stream.print("%4d (%5d) ", j, m->vtable_index());
4641 m->access_flags().print_on(&log_stream);
4642 log_stream.print(" -- ");
4643 m->print_name(&log_stream);
4644 log_stream.cr();
4645 }
4646 }
4647
4648 void VM_RedefineClasses::print_on_error(outputStream* st) const {
4649 VM_Operation::print_on_error(st);
4650 if (_the_class != nullptr) {
4651 ResourceMark rm;
4652 st->print_cr(", redefining class %s", _the_class->external_name());
4653 }
4654 }