1 /*
2 * Copyright (c) 2003, 2025, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
24
25 #include "cds/cdsConfig.hpp"
26 #include "cds/metaspaceShared.hpp"
27 #include "classfile/classFileStream.hpp"
28 #include "classfile/classLoaderDataGraph.hpp"
29 #include "classfile/classLoadInfo.hpp"
30 #include "classfile/javaClasses.inline.hpp"
31 #include "classfile/metadataOnStackMark.hpp"
32 #include "classfile/stackMapTable.hpp"
33 #include "classfile/symbolTable.hpp"
34 #include "classfile/klassFactory.hpp"
35 #include "classfile/verifier.hpp"
36 #include "classfile/vmClasses.hpp"
37 #include "classfile/vmSymbols.hpp"
38 #include "code/codeCache.hpp"
39 #include "compiler/compileBroker.hpp"
40 #include "interpreter/oopMapCache.hpp"
41 #include "interpreter/rewriter.hpp"
42 #include "jfr/jfrEvents.hpp"
43 #include "logging/logStream.hpp"
44 #include "memory/metadataFactory.hpp"
45 #include "memory/resourceArea.hpp"
46 #include "memory/universe.hpp"
47 #include "oops/annotations.hpp"
48 #include "oops/constantPool.hpp"
49 #include "oops/fieldStreams.inline.hpp"
50 #include "oops/klass.inline.hpp"
51 #include "oops/klassVtable.hpp"
52 #include "oops/method.hpp"
53 #include "oops/oop.inline.hpp"
54 #include "oops/recordComponent.hpp"
55 #include "prims/jvmtiImpl.hpp"
56 #include "prims/jvmtiRedefineClasses.hpp"
57 #include "prims/jvmtiThreadState.inline.hpp"
58 #include "prims/resolvedMethodTable.hpp"
59 #include "prims/methodComparator.hpp"
60 #include "runtime/atomic.hpp"
61 #include "runtime/deoptimization.hpp"
62 #include "runtime/handles.inline.hpp"
63 #include "runtime/jniHandles.inline.hpp"
64 #include "runtime/relocator.hpp"
65 #include "runtime/safepointVerifiers.hpp"
66 #include "utilities/bitMap.inline.hpp"
67 #include "utilities/checkedCast.hpp"
68 #include "utilities/events.hpp"
69 #include "utilities/macros.hpp"
70
71 Array<Method*>* VM_RedefineClasses::_old_methods = nullptr;
72 Array<Method*>* VM_RedefineClasses::_new_methods = nullptr;
73 Method** VM_RedefineClasses::_matching_old_methods = nullptr;
74 Method** VM_RedefineClasses::_matching_new_methods = nullptr;
75 Method** VM_RedefineClasses::_deleted_methods = nullptr;
76 Method** VM_RedefineClasses::_added_methods = nullptr;
77 int VM_RedefineClasses::_matching_methods_length = 0;
78 int VM_RedefineClasses::_deleted_methods_length = 0;
79 int VM_RedefineClasses::_added_methods_length = 0;
80
81 // This flag is global as the constructor does not reset it:
82 bool VM_RedefineClasses::_has_redefined_Object = false;
83 u8 VM_RedefineClasses::_id_counter = 0;
84
85 VM_RedefineClasses::VM_RedefineClasses(jint class_count,
86 const jvmtiClassDefinition *class_defs,
87 JvmtiClassLoadKind class_load_kind) {
88 _class_count = class_count;
89 _class_defs = class_defs;
90 _class_load_kind = class_load_kind;
91 _any_class_has_resolved_methods = false;
92 _res = JVMTI_ERROR_NONE;
93 _the_class = nullptr;
94 _id = next_id();
95 }
96
97 static inline InstanceKlass* get_ik(jclass def) {
98 oop mirror = JNIHandles::resolve_non_null(def);
99 return InstanceKlass::cast(java_lang_Class::as_Klass(mirror));
100 }
101
102 // If any of the classes are being redefined, wait
103 // Parallel constant pool merging leads to indeterminate constant pools.
104 void VM_RedefineClasses::lock_classes() {
105 JvmtiThreadState *state = JvmtiThreadState::state_for(JavaThread::current());
106 GrowableArray<Klass*>* redef_classes = state->get_classes_being_redefined();
107
108 MonitorLocker ml(RedefineClasses_lock);
109
110 if (redef_classes == nullptr) {
111 redef_classes = new (mtClass) GrowableArray<Klass*>(1, mtClass);
112 state->set_classes_being_redefined(redef_classes);
113 }
114
115 bool has_redefined;
116 do {
117 has_redefined = false;
118 // Go through classes each time until none are being redefined. Skip
119 // the ones that are being redefined by this thread currently. Class file
120 // load hook event may trigger new class redefine when we are redefining
121 // a class (after lock_classes()).
122 for (int i = 0; i < _class_count; i++) {
123 InstanceKlass* ik = get_ik(_class_defs[i].klass);
124 // Check if we are currently redefining the class in this thread already.
125 if (redef_classes->contains(ik)) {
126 assert(ik->is_being_redefined(), "sanity");
127 } else {
128 if (ik->is_being_redefined()) {
129 ml.wait();
130 has_redefined = true;
131 break; // for loop
132 }
133 }
134 }
135 } while (has_redefined);
136
137 for (int i = 0; i < _class_count; i++) {
138 InstanceKlass* ik = get_ik(_class_defs[i].klass);
139 redef_classes->push(ik); // Add to the _classes_being_redefined list
140 ik->set_is_being_redefined(true);
141 }
142 ml.notify_all();
143 }
144
145 void VM_RedefineClasses::unlock_classes() {
146 JvmtiThreadState *state = JvmtiThreadState::state_for(JavaThread::current());
147 GrowableArray<Klass*>* redef_classes = state->get_classes_being_redefined();
148 assert(redef_classes != nullptr, "_classes_being_redefined is not allocated");
149
150 MonitorLocker ml(RedefineClasses_lock);
151
152 for (int i = _class_count - 1; i >= 0; i--) {
153 InstanceKlass* def_ik = get_ik(_class_defs[i].klass);
154 if (redef_classes->length() > 0) {
155 // Remove the class from _classes_being_redefined list
156 Klass* k = redef_classes->pop();
157 assert(def_ik == k, "unlocking wrong class");
158 }
159 assert(def_ik->is_being_redefined(),
160 "should be being redefined to get here");
161
162 // Unlock after we finish all redefines for this class within
163 // the thread. Same class can be pushed to the list multiple
164 // times (not more than once by each recursive redefinition).
165 if (!redef_classes->contains(def_ik)) {
166 def_ik->set_is_being_redefined(false);
167 }
168 }
169 ml.notify_all();
170 }
171
172 bool VM_RedefineClasses::doit_prologue() {
173 if (_class_count == 0) {
174 _res = JVMTI_ERROR_NONE;
175 return false;
176 }
177 if (_class_defs == nullptr) {
178 _res = JVMTI_ERROR_NULL_POINTER;
179 return false;
180 }
181
182 for (int i = 0; i < _class_count; i++) {
183 if (_class_defs[i].klass == nullptr) {
184 _res = JVMTI_ERROR_INVALID_CLASS;
185 return false;
186 }
187 if (_class_defs[i].class_byte_count == 0) {
188 _res = JVMTI_ERROR_INVALID_CLASS_FORMAT;
189 return false;
190 }
191 if (_class_defs[i].class_bytes == nullptr) {
192 _res = JVMTI_ERROR_NULL_POINTER;
193 return false;
194 }
195
196 oop mirror = JNIHandles::resolve_non_null(_class_defs[i].klass);
197 // classes for primitives, arrays, and hidden classes
198 // cannot be redefined.
199 if (!is_modifiable_class(mirror)) {
200 _res = JVMTI_ERROR_UNMODIFIABLE_CLASS;
201 return false;
202 }
203 }
204
205 // Start timer after all the sanity checks; not quite accurate, but
206 // better than adding a bunch of stop() calls.
207 if (log_is_enabled(Info, redefine, class, timer)) {
208 _timer_vm_op_prologue.start();
209 }
210
211 lock_classes();
212 // We first load new class versions in the prologue, because somewhere down the
213 // call chain it is required that the current thread is a Java thread.
214 _res = load_new_class_versions();
215 if (_res != JVMTI_ERROR_NONE) {
216 // free any successfully created classes, since none are redefined
217 for (int i = 0; i < _class_count; i++) {
218 if (_scratch_classes[i] != nullptr) {
219 ClassLoaderData* cld = _scratch_classes[i]->class_loader_data();
220 // Free the memory for this class at class unloading time. Not before
221 // because CMS might think this is still live.
222 InstanceKlass* ik = get_ik(_class_defs[i].klass);
223 if (ik->get_cached_class_file() == _scratch_classes[i]->get_cached_class_file()) {
224 // Don't double-free cached_class_file copied from the original class if error.
225 _scratch_classes[i]->set_cached_class_file(nullptr);
226 }
227 cld->add_to_deallocate_list(InstanceKlass::cast(_scratch_classes[i]));
228 }
229 }
230 // Free os::malloc allocated memory in load_new_class_version.
231 os::free(_scratch_classes);
232 _timer_vm_op_prologue.stop();
233 unlock_classes();
234 return false;
235 }
236
237 _timer_vm_op_prologue.stop();
238 return true;
239 }
240
241 void VM_RedefineClasses::doit() {
242 Thread* current = Thread::current();
243
244 if (log_is_enabled(Info, redefine, class, timer)) {
245 _timer_vm_op_doit.start();
246 }
247
248 #if INCLUDE_CDS
249 if (CDSConfig::is_using_archive()) {
250 // Sharing is enabled so we remap the shared readonly space to
251 // shared readwrite, private just in case we need to redefine
252 // a shared class. We do the remap during the doit() phase of
253 // the safepoint to be safer.
254 if (!MetaspaceShared::remap_shared_readonly_as_readwrite()) {
255 log_info(redefine, class, load)("failed to remap shared readonly space to readwrite, private");
256 _res = JVMTI_ERROR_INTERNAL;
257 _timer_vm_op_doit.stop();
258 return;
259 }
260 }
261 #endif
262
263 // Mark methods seen on stack and everywhere else so old methods are not
264 // cleaned up if they're on the stack.
265 MetadataOnStackMark md_on_stack(/*walk_all_metadata*/true, /*redefinition_walk*/true);
266 HandleMark hm(current); // make sure any handles created are deleted
267 // before the stack walk again.
268
269 for (int i = 0; i < _class_count; i++) {
270 redefine_single_class(current, _class_defs[i].klass, _scratch_classes[i]);
271 }
272
273 // Flush all compiled code that depends on the classes redefined.
274 flush_dependent_code();
275
276 // Adjust constantpool caches and vtables for all classes
277 // that reference methods of the evolved classes.
278 // Have to do this after all classes are redefined and all methods that
279 // are redefined are marked as old.
280 AdjustAndCleanMetadata adjust_and_clean_metadata(current);
281 ClassLoaderDataGraph::classes_do(&adjust_and_clean_metadata);
282
283 // JSR-292 support
284 if (_any_class_has_resolved_methods) {
285 bool trace_name_printed = false;
286 ResolvedMethodTable::adjust_method_entries(&trace_name_printed);
287 }
288
289 // Increment flag indicating that some invariants are no longer true.
290 // See jvmtiExport.hpp for detailed explanation.
291 JvmtiExport::increment_redefinition_count();
292
293 // check_class() is optionally called for product bits, but is
294 // always called for non-product bits.
295 #ifdef PRODUCT
296 if (log_is_enabled(Trace, redefine, class, obsolete, metadata)) {
297 #endif
298 log_trace(redefine, class, obsolete, metadata)("calling check_class");
299 CheckClass check_class(current);
300 ClassLoaderDataGraph::classes_do(&check_class);
301 #ifdef PRODUCT
302 }
303 #endif
304
305 // Clean up any metadata now unreferenced while MetadataOnStackMark is set.
306 ClassLoaderDataGraph::clean_deallocate_lists(false);
307
308 _timer_vm_op_doit.stop();
309 }
310
311 void VM_RedefineClasses::doit_epilogue() {
312 unlock_classes();
313
314 // Free os::malloc allocated memory.
315 os::free(_scratch_classes);
316
317 // Reset the_class to null for error printing.
318 _the_class = nullptr;
319
320 if (log_is_enabled(Info, redefine, class, timer)) {
321 // Used to have separate timers for "doit" and "all", but the timer
322 // overhead skewed the measurements.
323 julong doit_time = _timer_vm_op_doit.milliseconds();
324 julong all_time = _timer_vm_op_prologue.milliseconds() + doit_time;
325
326 log_info(redefine, class, timer)
327 ("vm_op: all=" JULONG_FORMAT " prologue=" JULONG_FORMAT " doit=" JULONG_FORMAT,
328 all_time, (julong)_timer_vm_op_prologue.milliseconds(), doit_time);
329 log_info(redefine, class, timer)
330 ("redefine_single_class: phase1=" JULONG_FORMAT " phase2=" JULONG_FORMAT,
331 (julong)_timer_rsc_phase1.milliseconds(), (julong)_timer_rsc_phase2.milliseconds());
332 }
333 }
334
335 bool VM_RedefineClasses::is_modifiable_class(oop klass_mirror) {
336 // classes for primitives cannot be redefined
337 if (java_lang_Class::is_primitive(klass_mirror)) {
338 return false;
339 }
340 Klass* k = java_lang_Class::as_Klass(klass_mirror);
341 // classes for arrays cannot be redefined
342 if (k == nullptr || !k->is_instance_klass()) {
343 return false;
344 }
345
346 // Cannot redefine or retransform a hidden class.
347 if (InstanceKlass::cast(k)->is_hidden()) {
348 return false;
349 }
350 if (InstanceKlass::cast(k) == vmClasses::Continuation_klass()) {
351 // Don't redefine Continuation class. See 8302779.
352 return false;
353 }
354 return true;
355 }
356
357 // Append the current entry at scratch_i in scratch_cp to *merge_cp_p
358 // where the end of *merge_cp_p is specified by *merge_cp_length_p. For
359 // direct CP entries, there is just the current entry to append. For
360 // indirect and double-indirect CP entries, there are zero or more
361 // referenced CP entries along with the current entry to append.
362 // Indirect and double-indirect CP entries are handled by recursive
363 // calls to append_entry() as needed. The referenced CP entries are
364 // always appended to *merge_cp_p before the referee CP entry. These
365 // referenced CP entries may already exist in *merge_cp_p in which case
366 // there is nothing extra to append and only the current entry is
367 // appended.
368 void VM_RedefineClasses::append_entry(const constantPoolHandle& scratch_cp,
369 int scratch_i, constantPoolHandle *merge_cp_p, int *merge_cp_length_p) {
370
371 // append is different depending on entry tag type
372 switch (scratch_cp->tag_at(scratch_i).value()) {
373
374 // The old verifier is implemented outside the VM. It loads classes,
375 // but does not resolve constant pool entries directly so we never
376 // see Class entries here with the old verifier. Similarly the old
377 // verifier does not like Class entries in the input constant pool.
378 // The split-verifier is implemented in the VM so it can optionally
379 // and directly resolve constant pool entries to load classes. The
380 // split-verifier can accept either Class entries or UnresolvedClass
381 // entries in the input constant pool. We revert the appended copy
382 // back to UnresolvedClass so that either verifier will be happy
383 // with the constant pool entry.
384 //
385 // this is an indirect CP entry so it needs special handling
386 case JVM_CONSTANT_Class:
387 case JVM_CONSTANT_UnresolvedClass:
388 {
389 int name_i = scratch_cp->klass_name_index_at(scratch_i);
390 int new_name_i = find_or_append_indirect_entry(scratch_cp, name_i, merge_cp_p,
391 merge_cp_length_p);
392
393 if (new_name_i != name_i) {
394 log_trace(redefine, class, constantpool)
395 ("Class entry@%d name_index change: %d to %d",
396 *merge_cp_length_p, name_i, new_name_i);
397 }
398
399 (*merge_cp_p)->temp_unresolved_klass_at_put(*merge_cp_length_p, new_name_i);
400 if (scratch_i != *merge_cp_length_p) {
401 // The new entry in *merge_cp_p is at a different index than
402 // the new entry in scratch_cp so we need to map the index values.
403 map_index(scratch_cp, scratch_i, *merge_cp_length_p);
404 }
405 (*merge_cp_length_p)++;
406 } break;
407
408 // these are direct CP entries so they can be directly appended,
409 // but double and long take two constant pool entries
410 case JVM_CONSTANT_Double: // fall through
411 case JVM_CONSTANT_Long:
412 {
413 ConstantPool::copy_entry_to(scratch_cp, scratch_i, *merge_cp_p, *merge_cp_length_p);
414
415 if (scratch_i != *merge_cp_length_p) {
416 // The new entry in *merge_cp_p is at a different index than
417 // the new entry in scratch_cp so we need to map the index values.
418 map_index(scratch_cp, scratch_i, *merge_cp_length_p);
419 }
420 (*merge_cp_length_p) += 2;
421 } break;
422
423 // these are direct CP entries so they can be directly appended
424 case JVM_CONSTANT_Float: // fall through
425 case JVM_CONSTANT_Integer: // fall through
426 case JVM_CONSTANT_Utf8: // fall through
427
428 // This was an indirect CP entry, but it has been changed into
429 // Symbol*s so this entry can be directly appended.
430 case JVM_CONSTANT_String: // fall through
431 {
432 ConstantPool::copy_entry_to(scratch_cp, scratch_i, *merge_cp_p, *merge_cp_length_p);
433
434 if (scratch_i != *merge_cp_length_p) {
435 // The new entry in *merge_cp_p is at a different index than
436 // the new entry in scratch_cp so we need to map the index values.
437 map_index(scratch_cp, scratch_i, *merge_cp_length_p);
438 }
439 (*merge_cp_length_p)++;
440 } break;
441
442 // this is an indirect CP entry so it needs special handling
443 case JVM_CONSTANT_NameAndType:
444 {
445 int name_ref_i = scratch_cp->name_ref_index_at(scratch_i);
446 int new_name_ref_i = find_or_append_indirect_entry(scratch_cp, name_ref_i, merge_cp_p,
447 merge_cp_length_p);
448
449 int signature_ref_i = scratch_cp->signature_ref_index_at(scratch_i);
450 int new_signature_ref_i = find_or_append_indirect_entry(scratch_cp, signature_ref_i,
451 merge_cp_p, merge_cp_length_p);
452
453 // If the referenced entries already exist in *merge_cp_p, then
454 // both new_name_ref_i and new_signature_ref_i will both be 0.
455 // In that case, all we are appending is the current entry.
456 if (new_name_ref_i != name_ref_i) {
457 log_trace(redefine, class, constantpool)
458 ("NameAndType entry@%d name_ref_index change: %d to %d",
459 *merge_cp_length_p, name_ref_i, new_name_ref_i);
460 }
461 if (new_signature_ref_i != signature_ref_i) {
462 log_trace(redefine, class, constantpool)
463 ("NameAndType entry@%d signature_ref_index change: %d to %d",
464 *merge_cp_length_p, signature_ref_i, new_signature_ref_i);
465 }
466
467 (*merge_cp_p)->name_and_type_at_put(*merge_cp_length_p,
468 new_name_ref_i, new_signature_ref_i);
469 if (scratch_i != *merge_cp_length_p) {
470 // The new entry in *merge_cp_p is at a different index than
471 // the new entry in scratch_cp so we need to map the index values.
472 map_index(scratch_cp, scratch_i, *merge_cp_length_p);
473 }
474 (*merge_cp_length_p)++;
475 } break;
476
477 // this is a double-indirect CP entry so it needs special handling
478 case JVM_CONSTANT_Fieldref: // fall through
479 case JVM_CONSTANT_InterfaceMethodref: // fall through
480 case JVM_CONSTANT_Methodref:
481 {
482 int klass_ref_i = scratch_cp->uncached_klass_ref_index_at(scratch_i);
483 int new_klass_ref_i = find_or_append_indirect_entry(scratch_cp, klass_ref_i,
484 merge_cp_p, merge_cp_length_p);
485
486 int name_and_type_ref_i = scratch_cp->uncached_name_and_type_ref_index_at(scratch_i);
487 int new_name_and_type_ref_i = find_or_append_indirect_entry(scratch_cp, name_and_type_ref_i,
488 merge_cp_p, merge_cp_length_p);
489
490 const char *entry_name = nullptr;
491 switch (scratch_cp->tag_at(scratch_i).value()) {
492 case JVM_CONSTANT_Fieldref:
493 entry_name = "Fieldref";
494 (*merge_cp_p)->field_at_put(*merge_cp_length_p, new_klass_ref_i,
495 new_name_and_type_ref_i);
496 break;
497 case JVM_CONSTANT_InterfaceMethodref:
498 entry_name = "IFMethodref";
499 (*merge_cp_p)->interface_method_at_put(*merge_cp_length_p,
500 new_klass_ref_i, new_name_and_type_ref_i);
501 break;
502 case JVM_CONSTANT_Methodref:
503 entry_name = "Methodref";
504 (*merge_cp_p)->method_at_put(*merge_cp_length_p, new_klass_ref_i,
505 new_name_and_type_ref_i);
506 break;
507 default:
508 guarantee(false, "bad switch");
509 break;
510 }
511
512 if (klass_ref_i != new_klass_ref_i) {
513 log_trace(redefine, class, constantpool)
514 ("%s entry@%d class_index changed: %d to %d", entry_name, *merge_cp_length_p, klass_ref_i, new_klass_ref_i);
515 }
516 if (name_and_type_ref_i != new_name_and_type_ref_i) {
517 log_trace(redefine, class, constantpool)
518 ("%s entry@%d name_and_type_index changed: %d to %d",
519 entry_name, *merge_cp_length_p, name_and_type_ref_i, new_name_and_type_ref_i);
520 }
521
522 if (scratch_i != *merge_cp_length_p) {
523 // The new entry in *merge_cp_p is at a different index than
524 // the new entry in scratch_cp so we need to map the index values.
525 map_index(scratch_cp, scratch_i, *merge_cp_length_p);
526 }
527 (*merge_cp_length_p)++;
528 } break;
529
530 // this is an indirect CP entry so it needs special handling
531 case JVM_CONSTANT_MethodType:
532 {
533 int ref_i = scratch_cp->method_type_index_at(scratch_i);
534 int new_ref_i = find_or_append_indirect_entry(scratch_cp, ref_i, merge_cp_p,
535 merge_cp_length_p);
536 if (new_ref_i != ref_i) {
537 log_trace(redefine, class, constantpool)
538 ("MethodType entry@%d ref_index change: %d to %d", *merge_cp_length_p, ref_i, new_ref_i);
539 }
540 (*merge_cp_p)->method_type_index_at_put(*merge_cp_length_p, new_ref_i);
541 if (scratch_i != *merge_cp_length_p) {
542 // The new entry in *merge_cp_p is at a different index than
543 // the new entry in scratch_cp so we need to map the index values.
544 map_index(scratch_cp, scratch_i, *merge_cp_length_p);
545 }
546 (*merge_cp_length_p)++;
547 } break;
548
549 // this is an indirect CP entry so it needs special handling
550 case JVM_CONSTANT_MethodHandle:
551 {
552 int ref_kind = scratch_cp->method_handle_ref_kind_at(scratch_i);
553 int ref_i = scratch_cp->method_handle_index_at(scratch_i);
554 int new_ref_i = find_or_append_indirect_entry(scratch_cp, ref_i, merge_cp_p,
555 merge_cp_length_p);
556 if (new_ref_i != ref_i) {
557 log_trace(redefine, class, constantpool)
558 ("MethodHandle entry@%d ref_index change: %d to %d", *merge_cp_length_p, ref_i, new_ref_i);
559 }
560 (*merge_cp_p)->method_handle_index_at_put(*merge_cp_length_p, ref_kind, new_ref_i);
561 if (scratch_i != *merge_cp_length_p) {
562 // The new entry in *merge_cp_p is at a different index than
563 // the new entry in scratch_cp so we need to map the index values.
564 map_index(scratch_cp, scratch_i, *merge_cp_length_p);
565 }
566 (*merge_cp_length_p)++;
567 } break;
568
569 // this is an indirect CP entry so it needs special handling
570 case JVM_CONSTANT_Dynamic: // fall through
571 case JVM_CONSTANT_InvokeDynamic:
572 {
573 // Index of the bootstrap specifier in the operands array
574 int old_bs_i = scratch_cp->bootstrap_methods_attribute_index(scratch_i);
575 int new_bs_i = find_or_append_operand(scratch_cp, old_bs_i, merge_cp_p,
576 merge_cp_length_p);
577 // The bootstrap method NameAndType_info index
578 int old_ref_i = scratch_cp->bootstrap_name_and_type_ref_index_at(scratch_i);
579 int new_ref_i = find_or_append_indirect_entry(scratch_cp, old_ref_i, merge_cp_p,
580 merge_cp_length_p);
581 if (new_bs_i != old_bs_i) {
582 log_trace(redefine, class, constantpool)
583 ("Dynamic entry@%d bootstrap_method_attr_index change: %d to %d",
584 *merge_cp_length_p, old_bs_i, new_bs_i);
585 }
586 if (new_ref_i != old_ref_i) {
587 log_trace(redefine, class, constantpool)
588 ("Dynamic entry@%d name_and_type_index change: %d to %d", *merge_cp_length_p, old_ref_i, new_ref_i);
589 }
590
591 if (scratch_cp->tag_at(scratch_i).is_dynamic_constant())
592 (*merge_cp_p)->dynamic_constant_at_put(*merge_cp_length_p, new_bs_i, new_ref_i);
593 else
594 (*merge_cp_p)->invoke_dynamic_at_put(*merge_cp_length_p, new_bs_i, new_ref_i);
595 if (scratch_i != *merge_cp_length_p) {
596 // The new entry in *merge_cp_p is at a different index than
597 // the new entry in scratch_cp so we need to map the index values.
598 map_index(scratch_cp, scratch_i, *merge_cp_length_p);
599 }
600 (*merge_cp_length_p)++;
601 } break;
602
603 // At this stage, Class or UnresolvedClass could be in scratch_cp, but not
604 // ClassIndex
605 case JVM_CONSTANT_ClassIndex: // fall through
606
607 // Invalid is used as the tag for the second constant pool entry
608 // occupied by JVM_CONSTANT_Double or JVM_CONSTANT_Long. It should
609 // not be seen by itself.
610 case JVM_CONSTANT_Invalid: // fall through
611
612 // At this stage, String could be here, but not StringIndex
613 case JVM_CONSTANT_StringIndex: // fall through
614
615 // At this stage JVM_CONSTANT_UnresolvedClassInError should not be
616 // here
617 case JVM_CONSTANT_UnresolvedClassInError: // fall through
618
619 default:
620 {
621 // leave a breadcrumb
622 jbyte bad_value = scratch_cp->tag_at(scratch_i).value();
623 ShouldNotReachHere();
624 } break;
625 } // end switch tag value
626 } // end append_entry()
627
628
629 u2 VM_RedefineClasses::find_or_append_indirect_entry(const constantPoolHandle& scratch_cp,
630 int ref_i, constantPoolHandle *merge_cp_p, int *merge_cp_length_p) {
631
632 int new_ref_i = ref_i;
633 bool match = (ref_i < *merge_cp_length_p) &&
634 scratch_cp->compare_entry_to(ref_i, *merge_cp_p, ref_i);
635
636 if (!match) {
637 // forward reference in *merge_cp_p or not a direct match
638 int found_i = scratch_cp->find_matching_entry(ref_i, *merge_cp_p);
639 if (found_i != 0) {
640 guarantee(found_i != ref_i, "compare_entry_to() and find_matching_entry() do not agree");
641 // Found a matching entry somewhere else in *merge_cp_p so just need a mapping entry.
642 new_ref_i = found_i;
643 map_index(scratch_cp, ref_i, found_i);
644 } else {
645 // no match found so we have to append this entry to *merge_cp_p
646 append_entry(scratch_cp, ref_i, merge_cp_p, merge_cp_length_p);
647 // The above call to append_entry() can only append one entry
648 // so the post call query of *merge_cp_length_p is only for
649 // the sake of consistency.
650 new_ref_i = *merge_cp_length_p - 1;
651 }
652 }
653
654 // constant pool indices are u2, unless the merged constant pool overflows which
655 // we don't check for.
656 return checked_cast<u2>(new_ref_i);
657 } // end find_or_append_indirect_entry()
658
659
660 // Append a bootstrap specifier into the merge_cp operands that is semantically equal
661 // to the scratch_cp operands bootstrap specifier passed by the old_bs_i index.
662 // Recursively append new merge_cp entries referenced by the new bootstrap specifier.
663 void VM_RedefineClasses::append_operand(const constantPoolHandle& scratch_cp, const int old_bs_i,
664 constantPoolHandle *merge_cp_p, int *merge_cp_length_p) {
665
666 BSMAttributeEntry* old_bsme = scratch_cp->bsm_attribute_entry(old_bs_i);
667 u2 old_ref_i = old_bsme->bootstrap_method_index();
668 u2 new_ref_i = find_or_append_indirect_entry(scratch_cp, old_ref_i, merge_cp_p,
669 merge_cp_length_p);
670 if (new_ref_i != old_ref_i) {
671 log_trace(redefine, class, constantpool)
672 ("operands entry@%d bootstrap method ref_index change: %d to %d", _operands_cur_length, old_ref_i, new_ref_i);
673 }
674
675 Array<u2>* merge_ops = (*merge_cp_p)->operands();
676 int new_bs_i = _operands_cur_length;
677 // We have _operands_cur_length == 0 when the merge_cp operands is empty yet.
678 // However, the operand_offset_at(0) was set in the extend_operands() call.
679 int new_base = (new_bs_i == 0) ? (*merge_cp_p)->operand_offset_at(0)
680 : (*merge_cp_p)->operand_next_offset_at(new_bs_i - 1);
681 u2 argc = old_bsme->argument_count();
682
683 ConstantPool::operand_offset_at_put(merge_ops, _operands_cur_length, new_base);
684 merge_ops->at_put(new_base++, new_ref_i);
685 merge_ops->at_put(new_base++, argc);
686
687 for (int i = 0; i < argc; i++) {
688 u2 old_arg_ref_i = old_bsme->argument_index(i);
689 u2 new_arg_ref_i = find_or_append_indirect_entry(scratch_cp, old_arg_ref_i, merge_cp_p,
690 merge_cp_length_p);
691 merge_ops->at_put(new_base++, new_arg_ref_i);
692 if (new_arg_ref_i != old_arg_ref_i) {
693 log_trace(redefine, class, constantpool)
694 ("operands entry@%d bootstrap method argument ref_index change: %d to %d",
695 _operands_cur_length, old_arg_ref_i, new_arg_ref_i);
696 }
697 }
698 if (old_bs_i != _operands_cur_length) {
699 // The bootstrap specifier in *merge_cp_p is at a different index than
700 // that in scratch_cp so we need to map the index values.
701 map_operand_index(old_bs_i, new_bs_i);
702 }
703 _operands_cur_length++;
704 } // end append_operand()
705
706
707 int VM_RedefineClasses::find_or_append_operand(const constantPoolHandle& scratch_cp,
708 int old_bs_i, constantPoolHandle *merge_cp_p, int *merge_cp_length_p) {
709
710 int new_bs_i = old_bs_i; // bootstrap specifier index
711 bool match = (old_bs_i < _operands_cur_length) &&
712 scratch_cp->compare_operand_to(old_bs_i, *merge_cp_p, old_bs_i);
713
714 if (!match) {
715 // forward reference in *merge_cp_p or not a direct match
716 int found_i = scratch_cp->find_matching_operand(old_bs_i, *merge_cp_p,
717 _operands_cur_length);
718 if (found_i != -1) {
719 guarantee(found_i != old_bs_i, "compare_operand_to() and find_matching_operand() disagree");
720 // found a matching operand somewhere else in *merge_cp_p so just need a mapping
721 new_bs_i = found_i;
722 map_operand_index(old_bs_i, found_i);
723 } else {
724 // no match found so we have to append this bootstrap specifier to *merge_cp_p
725 append_operand(scratch_cp, old_bs_i, merge_cp_p, merge_cp_length_p);
726 new_bs_i = _operands_cur_length - 1;
727 }
728 }
729 return new_bs_i;
730 } // end find_or_append_operand()
731
732
733 void VM_RedefineClasses::finalize_operands_merge(const constantPoolHandle& merge_cp, TRAPS) {
734 if (merge_cp->operands() == nullptr) {
735 return;
736 }
737 // Shrink the merge_cp operands
738 merge_cp->shrink_operands(_operands_cur_length, CHECK);
739
740 if (log_is_enabled(Trace, redefine, class, constantpool)) {
741 // don't want to loop unless we are tracing
742 int count = 0;
743 for (int i = 1; i < _operands_index_map_p->length(); i++) {
744 int value = _operands_index_map_p->at(i);
745 if (value != -1) {
746 log_trace(redefine, class, constantpool)("operands_index_map[%d]: old=%d new=%d", count, i, value);
747 count++;
748 }
749 }
750 }
751 // Clean-up
752 _operands_index_map_p = nullptr;
753 _operands_cur_length = 0;
754 _operands_index_map_count = 0;
755 } // end finalize_operands_merge()
756
757 // Symbol* comparator for qsort
758 // The caller must have an active ResourceMark.
759 static int symcmp(const void* a, const void* b) {
760 char* astr = (*(Symbol**)a)->as_C_string();
761 char* bstr = (*(Symbol**)b)->as_C_string();
762 return strcmp(astr, bstr);
763 }
764
765 // The caller must have an active ResourceMark.
766 static jvmtiError check_attribute_arrays(const char* attr_name,
767 InstanceKlass* the_class, InstanceKlass* scratch_class,
768 Array<u2>* the_array, Array<u2>* scr_array) {
769 bool the_array_exists = the_array != Universe::the_empty_short_array();
770 bool scr_array_exists = scr_array != Universe::the_empty_short_array();
771
772 int array_len = the_array->length();
773 if (the_array_exists && scr_array_exists) {
774 if (array_len != scr_array->length()) {
775 log_trace(redefine, class)
776 ("redefined class %s attribute change error: %s len=%d changed to len=%d",
777 the_class->external_name(), attr_name, array_len, scr_array->length());
778 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_CLASS_ATTRIBUTE_CHANGED;
779 }
780
781 // The order of entries in the attribute array is not specified so we
782 // have to explicitly check for the same contents. We do this by copying
783 // the referenced symbols into their own arrays, sorting them and then
784 // comparing each element pair.
785
786 Symbol** the_syms = NEW_RESOURCE_ARRAY_RETURN_NULL(Symbol*, array_len);
787 Symbol** scr_syms = NEW_RESOURCE_ARRAY_RETURN_NULL(Symbol*, array_len);
788
789 if (the_syms == nullptr || scr_syms == nullptr) {
790 return JVMTI_ERROR_OUT_OF_MEMORY;
791 }
792
793 for (int i = 0; i < array_len; i++) {
794 int the_cp_index = the_array->at(i);
795 int scr_cp_index = scr_array->at(i);
796 the_syms[i] = the_class->constants()->klass_name_at(the_cp_index);
797 scr_syms[i] = scratch_class->constants()->klass_name_at(scr_cp_index);
798 }
799
800 qsort(the_syms, array_len, sizeof(Symbol*), symcmp);
801 qsort(scr_syms, array_len, sizeof(Symbol*), symcmp);
802
803 for (int i = 0; i < array_len; i++) {
804 if (the_syms[i] != scr_syms[i]) {
805 log_info(redefine, class)
806 ("redefined class %s attribute change error: %s[%d]: %s changed to %s",
807 the_class->external_name(), attr_name, i,
808 the_syms[i]->as_C_string(), scr_syms[i]->as_C_string());
809 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_CLASS_ATTRIBUTE_CHANGED;
810 }
811 }
812 } else if (the_array_exists ^ scr_array_exists) {
813 const char* action_str = (the_array_exists) ? "removed" : "added";
814 log_info(redefine, class)
815 ("redefined class %s attribute change error: %s attribute %s",
816 the_class->external_name(), attr_name, action_str);
817 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_CLASS_ATTRIBUTE_CHANGED;
818 }
819 return JVMTI_ERROR_NONE;
820 }
821
822 static jvmtiError check_nest_attributes(InstanceKlass* the_class,
823 InstanceKlass* scratch_class) {
824 // Check whether the class NestHost attribute has been changed.
825 Thread* thread = Thread::current();
826 ResourceMark rm(thread);
827 u2 the_nest_host_idx = the_class->nest_host_index();
828 u2 scr_nest_host_idx = scratch_class->nest_host_index();
829
830 if (the_nest_host_idx != 0 && scr_nest_host_idx != 0) {
831 Symbol* the_sym = the_class->constants()->klass_name_at(the_nest_host_idx);
832 Symbol* scr_sym = scratch_class->constants()->klass_name_at(scr_nest_host_idx);
833 if (the_sym != scr_sym) {
834 log_info(redefine, class, nestmates)
835 ("redefined class %s attribute change error: NestHost class: %s replaced with: %s",
836 the_class->external_name(), the_sym->as_C_string(), scr_sym->as_C_string());
837 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_CLASS_ATTRIBUTE_CHANGED;
838 }
839 } else if ((the_nest_host_idx == 0) ^ (scr_nest_host_idx == 0)) {
840 const char* action_str = (the_nest_host_idx != 0) ? "removed" : "added";
841 log_info(redefine, class, nestmates)
842 ("redefined class %s attribute change error: NestHost attribute %s",
843 the_class->external_name(), action_str);
844 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_CLASS_ATTRIBUTE_CHANGED;
845 }
846
847 // Check whether the class NestMembers attribute has been changed.
848 return check_attribute_arrays("NestMembers",
849 the_class, scratch_class,
850 the_class->nest_members(),
851 scratch_class->nest_members());
852 }
853
854 // Return an error status if the class Record attribute was changed.
855 static jvmtiError check_record_attribute(InstanceKlass* the_class, InstanceKlass* scratch_class) {
856 // Get lists of record components.
857 Array<RecordComponent*>* the_record = the_class->record_components();
858 Array<RecordComponent*>* scr_record = scratch_class->record_components();
859 bool the_record_exists = the_record != nullptr;
860 bool scr_record_exists = scr_record != nullptr;
861
862 if (the_record_exists && scr_record_exists) {
863 int the_num_components = the_record->length();
864 int scr_num_components = scr_record->length();
865 if (the_num_components != scr_num_components) {
866 log_info(redefine, class, record)
867 ("redefined class %s attribute change error: Record num_components=%d changed to num_components=%d",
868 the_class->external_name(), the_num_components, scr_num_components);
869 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_CLASS_ATTRIBUTE_CHANGED;
870 }
871
872 // Compare each field in each record component.
873 ConstantPool* the_cp = the_class->constants();
874 ConstantPool* scr_cp = scratch_class->constants();
875 for (int x = 0; x < the_num_components; x++) {
876 RecordComponent* the_component = the_record->at(x);
877 RecordComponent* scr_component = scr_record->at(x);
878 const Symbol* const the_name = the_cp->symbol_at(the_component->name_index());
879 const Symbol* const scr_name = scr_cp->symbol_at(scr_component->name_index());
880 const Symbol* const the_descr = the_cp->symbol_at(the_component->descriptor_index());
881 const Symbol* const scr_descr = scr_cp->symbol_at(scr_component->descriptor_index());
882 if (the_name != scr_name || the_descr != scr_descr) {
883 log_info(redefine, class, record)
884 ("redefined class %s attribute change error: Record name_index, descriptor_index, and/or attributes_count changed",
885 the_class->external_name());
886 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_CLASS_ATTRIBUTE_CHANGED;
887 }
888
889 int the_gen_sig = the_component->generic_signature_index();
890 int scr_gen_sig = scr_component->generic_signature_index();
891 const Symbol* const the_gen_sig_sym = (the_gen_sig == 0 ? nullptr :
892 the_cp->symbol_at(the_component->generic_signature_index()));
893 const Symbol* const scr_gen_sig_sym = (scr_gen_sig == 0 ? nullptr :
894 scr_cp->symbol_at(scr_component->generic_signature_index()));
895 if (the_gen_sig_sym != scr_gen_sig_sym) {
896 log_info(redefine, class, record)
897 ("redefined class %s attribute change error: Record generic_signature attribute changed",
898 the_class->external_name());
899 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_CLASS_ATTRIBUTE_CHANGED;
900 }
901
902 // It's okay if a record component's annotations were changed.
903 }
904
905 } else if (the_record_exists ^ scr_record_exists) {
906 const char* action_str = (the_record_exists) ? "removed" : "added";
907 log_info(redefine, class, record)
908 ("redefined class %s attribute change error: Record attribute %s",
909 the_class->external_name(), action_str);
910 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_CLASS_ATTRIBUTE_CHANGED;
911 }
912
913 return JVMTI_ERROR_NONE;
914 }
915
916
917 static jvmtiError check_permitted_subclasses_attribute(InstanceKlass* the_class,
918 InstanceKlass* scratch_class) {
919 Thread* thread = Thread::current();
920 ResourceMark rm(thread);
921
922 // Check whether the class PermittedSubclasses attribute has been changed.
923 return check_attribute_arrays("PermittedSubclasses",
924 the_class, scratch_class,
925 the_class->permitted_subclasses(),
926 scratch_class->permitted_subclasses());
927 }
928
929 static bool can_add_or_delete(Method* m) {
930 // Compatibility mode
931 return (AllowRedefinitionToAddDeleteMethods &&
932 (m->is_private() && (m->is_static() || m->is_final())));
933 }
934
935 jvmtiError VM_RedefineClasses::compare_and_normalize_class_versions(
936 InstanceKlass* the_class,
937 InstanceKlass* scratch_class) {
938 int i;
939
940 // Check superclasses, or rather their names, since superclasses themselves can be
941 // requested to replace.
942 // Check for null superclass first since this might be java.lang.Object
943 if (the_class->super() != scratch_class->super() &&
944 (the_class->super() == nullptr || scratch_class->super() == nullptr ||
945 the_class->super()->name() !=
946 scratch_class->super()->name())) {
947 log_info(redefine, class, normalize)
948 ("redefined class %s superclass change error: superclass changed from %s to %s.",
949 the_class->external_name(),
950 the_class->super() == nullptr ? "null" : the_class->super()->external_name(),
951 scratch_class->super() == nullptr ? "null" : scratch_class->super()->external_name());
952 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_HIERARCHY_CHANGED;
953 }
954
955 // Check if the number, names and order of directly implemented interfaces are the same.
956 // I think in principle we should just check if the sets of names of directly implemented
957 // interfaces are the same, i.e. the order of declaration (which, however, if changed in the
958 // .java file, also changes in .class file) should not matter. However, comparing sets is
959 // technically a bit more difficult, and, more importantly, I am not sure at present that the
960 // order of interfaces does not matter on the implementation level, i.e. that the VM does not
961 // rely on it somewhere.
962 Array<InstanceKlass*>* k_interfaces = the_class->local_interfaces();
963 Array<InstanceKlass*>* k_new_interfaces = scratch_class->local_interfaces();
964 int n_intfs = k_interfaces->length();
965 if (n_intfs != k_new_interfaces->length()) {
966 log_info(redefine, class, normalize)
967 ("redefined class %s interfaces change error: number of implemented interfaces changed from %d to %d.",
968 the_class->external_name(), n_intfs, k_new_interfaces->length());
969 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_HIERARCHY_CHANGED;
970 }
971 for (i = 0; i < n_intfs; i++) {
972 if (k_interfaces->at(i)->name() !=
973 k_new_interfaces->at(i)->name()) {
974 log_info(redefine, class, normalize)
975 ("redefined class %s interfaces change error: interface changed from %s to %s.",
976 the_class->external_name(),
977 k_interfaces->at(i)->external_name(), k_new_interfaces->at(i)->external_name());
978 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_HIERARCHY_CHANGED;
979 }
980 }
981
982 // Check whether class is in the error init state.
983 if (the_class->is_in_error_state()) {
984 log_info(redefine, class, normalize)
985 ("redefined class %s is in error init state.", the_class->external_name());
986 // TBD #5057930: special error code is needed in 1.6
987 return JVMTI_ERROR_INVALID_CLASS;
988 }
989
990 // Check whether the nest-related attributes have been changed.
991 jvmtiError err = check_nest_attributes(the_class, scratch_class);
992 if (err != JVMTI_ERROR_NONE) {
993 return err;
994 }
995
996 // Check whether the Record attribute has been changed.
997 err = check_record_attribute(the_class, scratch_class);
998 if (err != JVMTI_ERROR_NONE) {
999 return err;
1000 }
1001
1002 // Check whether the PermittedSubclasses attribute has been changed.
1003 err = check_permitted_subclasses_attribute(the_class, scratch_class);
1004 if (err != JVMTI_ERROR_NONE) {
1005 return err;
1006 }
1007
1008 // Check whether class modifiers are the same.
1009 u2 old_flags = the_class->access_flags().as_class_flags();
1010 u2 new_flags = scratch_class->access_flags().as_class_flags();
1011 if (old_flags != new_flags) {
1012 log_info(redefine, class, normalize)
1013 ("redefined class %s modifiers change error: modifiers changed from %d to %d.",
1014 the_class->external_name(), old_flags, new_flags);
1015 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_CLASS_MODIFIERS_CHANGED;
1016 }
1017
1018 // Check if the number, names, types and order of fields declared in these classes
1019 // are the same.
1020 JavaFieldStream old_fs(the_class);
1021 JavaFieldStream new_fs(scratch_class);
1022 for (; !old_fs.done() && !new_fs.done(); old_fs.next(), new_fs.next()) {
1023 // name and signature
1024 Symbol* name_sym1 = the_class->constants()->symbol_at(old_fs.name_index());
1025 Symbol* sig_sym1 = the_class->constants()->symbol_at(old_fs.signature_index());
1026 Symbol* name_sym2 = scratch_class->constants()->symbol_at(new_fs.name_index());
1027 Symbol* sig_sym2 = scratch_class->constants()->symbol_at(new_fs.signature_index());
1028 if (name_sym1 != name_sym2 || sig_sym1 != sig_sym2) {
1029 log_info(redefine, class, normalize)
1030 ("redefined class %s fields change error: field %s %s changed to %s %s.",
1031 the_class->external_name(),
1032 sig_sym1->as_C_string(), name_sym1->as_C_string(),
1033 sig_sym2->as_C_string(), name_sym2->as_C_string());
1034 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_SCHEMA_CHANGED;
1035 }
1036 // offset
1037 if (old_fs.offset() != new_fs.offset()) {
1038 log_info(redefine, class, normalize)
1039 ("redefined class %s field %s change error: offset changed from %d to %d.",
1040 the_class->external_name(), name_sym2->as_C_string(), old_fs.offset(), new_fs.offset());
1041 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_SCHEMA_CHANGED;
1042 }
1043 // access
1044 old_flags = old_fs.access_flags().as_field_flags();
1045 new_flags = new_fs.access_flags().as_field_flags();
1046 if (old_flags != new_flags) {
1047 log_info(redefine, class, normalize)
1048 ("redefined class %s field %s change error: modifiers changed from %d to %d.",
1049 the_class->external_name(), name_sym2->as_C_string(), old_flags, new_flags);
1050 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_SCHEMA_CHANGED;
1051 }
1052 }
1053
1054 // If both streams aren't done then we have a differing number of
1055 // fields.
1056 if (!old_fs.done() || !new_fs.done()) {
1057 const char* action = old_fs.done() ? "added" : "deleted";
1058 log_info(redefine, class, normalize)
1059 ("redefined class %s fields change error: some fields were %s.",
1060 the_class->external_name(), action);
1061 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_SCHEMA_CHANGED;
1062 }
1063
1064 // Do a parallel walk through the old and new methods. Detect
1065 // cases where they match (exist in both), have been added in
1066 // the new methods, or have been deleted (exist only in the
1067 // old methods). The class file parser places methods in order
1068 // by method name, but does not order overloaded methods by
1069 // signature. In order to determine what fate befell the methods,
1070 // this code places the overloaded new methods that have matching
1071 // old methods in the same order as the old methods and places
1072 // new overloaded methods at the end of overloaded methods of
1073 // that name. The code for this order normalization is adapted
1074 // from the algorithm used in InstanceKlass::find_method().
1075 // Since we are swapping out of order entries as we find them,
1076 // we only have to search forward through the overloaded methods.
1077 // Methods which are added and have the same name as an existing
1078 // method (but different signature) will be put at the end of
1079 // the methods with that name, and the name mismatch code will
1080 // handle them.
1081 Array<Method*>* k_old_methods(the_class->methods());
1082 Array<Method*>* k_new_methods(scratch_class->methods());
1083 int n_old_methods = k_old_methods->length();
1084 int n_new_methods = k_new_methods->length();
1085 Thread* thread = Thread::current();
1086
1087 int ni = 0;
1088 int oi = 0;
1089 while (true) {
1090 Method* k_old_method;
1091 Method* k_new_method;
1092 enum { matched, added, deleted, undetermined } method_was = undetermined;
1093
1094 if (oi >= n_old_methods) {
1095 if (ni >= n_new_methods) {
1096 break; // we've looked at everything, done
1097 }
1098 // New method at the end
1099 k_new_method = k_new_methods->at(ni);
1100 method_was = added;
1101 } else if (ni >= n_new_methods) {
1102 // Old method, at the end, is deleted
1103 k_old_method = k_old_methods->at(oi);
1104 method_was = deleted;
1105 } else {
1106 // There are more methods in both the old and new lists
1107 k_old_method = k_old_methods->at(oi);
1108 k_new_method = k_new_methods->at(ni);
1109 if (k_old_method->name() != k_new_method->name()) {
1110 // Methods are sorted by method name, so a mismatch means added
1111 // or deleted
1112 if (k_old_method->name()->fast_compare(k_new_method->name()) > 0) {
1113 method_was = added;
1114 } else {
1115 method_was = deleted;
1116 }
1117 } else if (k_old_method->signature() == k_new_method->signature()) {
1118 // Both the name and signature match
1119 method_was = matched;
1120 } else {
1121 // The name matches, but the signature doesn't, which means we have to
1122 // search forward through the new overloaded methods.
1123 int nj; // outside the loop for post-loop check
1124 for (nj = ni + 1; nj < n_new_methods; nj++) {
1125 Method* m = k_new_methods->at(nj);
1126 if (k_old_method->name() != m->name()) {
1127 // reached another method name so no more overloaded methods
1128 method_was = deleted;
1129 break;
1130 }
1131 if (k_old_method->signature() == m->signature()) {
1132 // found a match so swap the methods
1133 k_new_methods->at_put(ni, m);
1134 k_new_methods->at_put(nj, k_new_method);
1135 k_new_method = m;
1136 method_was = matched;
1137 break;
1138 }
1139 }
1140
1141 if (nj >= n_new_methods) {
1142 // reached the end without a match; so method was deleted
1143 method_was = deleted;
1144 }
1145 }
1146 }
1147
1148 switch (method_was) {
1149 case matched:
1150 // methods match, be sure modifiers do too
1151 old_flags = k_old_method->access_flags().as_method_flags();
1152 new_flags = k_new_method->access_flags().as_method_flags();
1153 if ((old_flags ^ new_flags) & ~(JVM_ACC_NATIVE)) {
1154 log_info(redefine, class, normalize)
1155 ("redefined class %s method %s modifiers error: modifiers changed from %d to %d",
1156 the_class->external_name(), k_old_method->name_and_sig_as_C_string(), old_flags, new_flags);
1157 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_METHOD_MODIFIERS_CHANGED;
1158 }
1159 {
1160 u2 new_num = k_new_method->method_idnum();
1161 u2 old_num = k_old_method->method_idnum();
1162 if (new_num != old_num) {
1163 Method* idnum_owner = scratch_class->method_with_idnum(old_num);
1164 if (idnum_owner != nullptr) {
1165 // There is already a method assigned this idnum -- switch them
1166 // Take current and original idnum from the new_method
1167 idnum_owner->set_method_idnum(new_num);
1168 idnum_owner->set_orig_method_idnum(k_new_method->orig_method_idnum());
1169 }
1170 // Take current and original idnum from the old_method
1171 k_new_method->set_method_idnum(old_num);
1172 k_new_method->set_orig_method_idnum(k_old_method->orig_method_idnum());
1173 if (thread->has_pending_exception()) {
1174 return JVMTI_ERROR_OUT_OF_MEMORY;
1175 }
1176 }
1177 }
1178 JFR_ONLY(k_new_method->copy_trace_flags(k_old_method->trace_flags());)
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_operand_index(int old_index) {
1274 if (_operands_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 >= _operands_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 = _operands_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_operand_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 Klass* _scratch_class;
1312 OopHandle _scratch_mirror;
1313
1314 public:
1315
1316 RedefineVerifyMark(Klass* the_class, Klass* 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
1360 log_debug(redefine, class, load)
1361 ("loading name=%s kind=%d (avail_mem=" UINT64_FORMAT "K)",
1362 the_class->external_name(), _class_load_kind, os::available_memory() >> 10);
1363
1364 ClassFileStream st((u1*)_class_defs[i].class_bytes,
1365 _class_defs[i].class_byte_count,
1366 "__VM_RedefineClasses__");
1367
1368 // Set redefined class handle in JvmtiThreadState class.
1369 // This redefined class is sent to agent event handler for class file
1370 // load hook event.
1371 state->set_class_being_redefined(the_class, _class_load_kind);
1372
1373 JavaThread* THREAD = current; // For exception macros.
1374 ExceptionMark em(THREAD);
1375 Handle protection_domain(THREAD, the_class->protection_domain());
1376 ClassLoadInfo cl_info(protection_domain);
1377 // Parse and create a class from the bytes, but this class isn't added
1378 // to the dictionary, so do not call resolve_from_stream.
1379 InstanceKlass* scratch_class = KlassFactory::create_from_stream(&st,
1380 the_class->name(),
1381 the_class->class_loader_data(),
1382 cl_info,
1383 THREAD);
1384
1385 // Clear class_being_redefined just to be sure.
1386 state->clear_class_being_redefined();
1387
1388 // TODO: if this is retransform, and nothing changed we can skip it
1389
1390 // Need to clean up allocated InstanceKlass if there's an error so assign
1391 // the result here. Caller deallocates all the scratch classes in case of
1392 // an error.
1393 _scratch_classes[i] = scratch_class;
1394
1395 if (HAS_PENDING_EXCEPTION) {
1396 Symbol* ex_name = PENDING_EXCEPTION->klass()->name();
1397 log_info(redefine, class, load, exceptions)("create_from_stream exception: '%s'", ex_name->as_C_string());
1398 CLEAR_PENDING_EXCEPTION;
1399
1400 if (ex_name == vmSymbols::java_lang_UnsupportedClassVersionError()) {
1401 return JVMTI_ERROR_UNSUPPORTED_VERSION;
1402 } else if (ex_name == vmSymbols::java_lang_ClassFormatError()) {
1403 return JVMTI_ERROR_INVALID_CLASS_FORMAT;
1404 } else if (ex_name == vmSymbols::java_lang_ClassCircularityError()) {
1405 return JVMTI_ERROR_CIRCULAR_CLASS_DEFINITION;
1406 } else if (ex_name == vmSymbols::java_lang_NoClassDefFoundError()) {
1407 // The message will be "XXX (wrong name: YYY)"
1408 return JVMTI_ERROR_NAMES_DONT_MATCH;
1409 } else if (ex_name == vmSymbols::java_lang_OutOfMemoryError()) {
1410 return JVMTI_ERROR_OUT_OF_MEMORY;
1411 } else { // Just in case more exceptions can be thrown..
1412 return JVMTI_ERROR_FAILS_VERIFICATION;
1413 }
1414 }
1415
1416 // Ensure class is linked before redefine
1417 if (!the_class->is_linked()) {
1418 the_class->link_class(THREAD);
1419 if (HAS_PENDING_EXCEPTION) {
1420 Symbol* ex_name = PENDING_EXCEPTION->klass()->name();
1421 oop message = java_lang_Throwable::message(PENDING_EXCEPTION);
1422 if (message != nullptr) {
1423 char* ex_msg = java_lang_String::as_utf8_string(message);
1424 log_info(redefine, class, load, exceptions)("link_class exception: '%s %s'",
1425 ex_name->as_C_string(), ex_msg);
1426 } else {
1427 log_info(redefine, class, load, exceptions)("link_class exception: '%s'",
1428 ex_name->as_C_string());
1429 }
1430 CLEAR_PENDING_EXCEPTION;
1431 if (ex_name == vmSymbols::java_lang_OutOfMemoryError()) {
1432 return JVMTI_ERROR_OUT_OF_MEMORY;
1433 } else if (ex_name == vmSymbols::java_lang_NoClassDefFoundError()) {
1434 return JVMTI_ERROR_INVALID_CLASS;
1435 } else {
1436 return JVMTI_ERROR_INTERNAL;
1437 }
1438 }
1439 }
1440
1441 // Do the validity checks in compare_and_normalize_class_versions()
1442 // before verifying the byte codes. By doing these checks first, we
1443 // limit the number of functions that require redirection from
1444 // the_class to scratch_class. In particular, we don't have to
1445 // modify JNI GetSuperclass() and thus won't change its performance.
1446 jvmtiError res = compare_and_normalize_class_versions(the_class,
1447 scratch_class);
1448 if (res != JVMTI_ERROR_NONE) {
1449 return res;
1450 }
1451
1452 // verify what the caller passed us
1453 {
1454 // The bug 6214132 caused the verification to fail.
1455 // Information about the_class and scratch_class is temporarily
1456 // recorded into jvmtiThreadState. This data is used to redirect
1457 // the_class to scratch_class in the JVM_* functions called by the
1458 // verifier. Please, refer to jvmtiThreadState.hpp for the detailed
1459 // description.
1460 RedefineVerifyMark rvm(the_class, scratch_class, state);
1461 Verifier::verify(scratch_class, true, THREAD);
1462 }
1463
1464 if (HAS_PENDING_EXCEPTION) {
1465 Symbol* ex_name = PENDING_EXCEPTION->klass()->name();
1466 log_info(redefine, class, load, exceptions)("verify_byte_codes exception: '%s'", ex_name->as_C_string());
1467 CLEAR_PENDING_EXCEPTION;
1468 if (ex_name == vmSymbols::java_lang_OutOfMemoryError()) {
1469 return JVMTI_ERROR_OUT_OF_MEMORY;
1470 } else {
1471 // tell the caller the bytecodes are bad
1472 return JVMTI_ERROR_FAILS_VERIFICATION;
1473 }
1474 }
1475
1476 res = merge_cp_and_rewrite(the_class, scratch_class, THREAD);
1477 if (HAS_PENDING_EXCEPTION) {
1478 Symbol* ex_name = PENDING_EXCEPTION->klass()->name();
1479 log_info(redefine, class, load, exceptions)("merge_cp_and_rewrite exception: '%s'", ex_name->as_C_string());
1480 CLEAR_PENDING_EXCEPTION;
1481 if (ex_name == vmSymbols::java_lang_OutOfMemoryError()) {
1482 return JVMTI_ERROR_OUT_OF_MEMORY;
1483 } else {
1484 return JVMTI_ERROR_INTERNAL;
1485 }
1486 }
1487
1488 #ifdef ASSERT
1489 {
1490 // verify what we have done during constant pool merging
1491 {
1492 RedefineVerifyMark rvm(the_class, scratch_class, state);
1493 Verifier::verify(scratch_class, true, THREAD);
1494 }
1495
1496 if (HAS_PENDING_EXCEPTION) {
1497 Symbol* ex_name = PENDING_EXCEPTION->klass()->name();
1498 log_info(redefine, class, load, exceptions)
1499 ("verify_byte_codes post merge-CP exception: '%s'", ex_name->as_C_string());
1500 CLEAR_PENDING_EXCEPTION;
1501 if (ex_name == vmSymbols::java_lang_OutOfMemoryError()) {
1502 return JVMTI_ERROR_OUT_OF_MEMORY;
1503 } else {
1504 // tell the caller that constant pool merging screwed up
1505 return JVMTI_ERROR_INTERNAL;
1506 }
1507 }
1508 }
1509 #endif // ASSERT
1510
1511 Rewriter::rewrite(scratch_class, THREAD);
1512 if (!HAS_PENDING_EXCEPTION) {
1513 scratch_class->link_methods(THREAD);
1514 }
1515 if (HAS_PENDING_EXCEPTION) {
1516 Symbol* ex_name = PENDING_EXCEPTION->klass()->name();
1517 log_info(redefine, class, load, exceptions)
1518 ("Rewriter::rewrite or link_methods exception: '%s'", ex_name->as_C_string());
1519 CLEAR_PENDING_EXCEPTION;
1520 if (ex_name == vmSymbols::java_lang_OutOfMemoryError()) {
1521 return JVMTI_ERROR_OUT_OF_MEMORY;
1522 } else {
1523 return JVMTI_ERROR_INTERNAL;
1524 }
1525 }
1526
1527 log_debug(redefine, class, load)
1528 ("loaded name=%s (avail_mem=" UINT64_FORMAT "K)", the_class->external_name(), os::available_memory() >> 10);
1529 }
1530
1531 return JVMTI_ERROR_NONE;
1532 }
1533
1534
1535 // Map old_index to new_index as needed. scratch_cp is only needed
1536 // for log calls.
1537 void VM_RedefineClasses::map_index(const constantPoolHandle& scratch_cp,
1538 int old_index, int new_index) {
1539 if (find_new_index(old_index) != 0) {
1540 // old_index is already mapped
1541 return;
1542 }
1543
1544 if (old_index == new_index) {
1545 // no mapping is needed
1546 return;
1547 }
1548
1549 _index_map_p->at_put(old_index, new_index);
1550 _index_map_count++;
1551
1552 log_trace(redefine, class, constantpool)
1553 ("mapped tag %d at index %d to %d", scratch_cp->tag_at(old_index).value(), old_index, new_index);
1554 } // end map_index()
1555
1556
1557 // Map old_index to new_index as needed.
1558 void VM_RedefineClasses::map_operand_index(int old_index, int new_index) {
1559 if (find_new_operand_index(old_index) != -1) {
1560 // old_index is already mapped
1561 return;
1562 }
1563
1564 if (old_index == new_index) {
1565 // no mapping is needed
1566 return;
1567 }
1568
1569 _operands_index_map_p->at_put(old_index, new_index);
1570 _operands_index_map_count++;
1571
1572 log_trace(redefine, class, constantpool)("mapped bootstrap specifier at index %d to %d", old_index, new_index);
1573 } // end map_index()
1574
1575
1576 // Merge old_cp and scratch_cp and return the results of the merge via
1577 // merge_cp_p. The number of entries in merge_cp_p is returned via
1578 // merge_cp_length_p. The entries in old_cp occupy the same locations
1579 // in merge_cp_p. Also creates a map of indices from entries in
1580 // scratch_cp to the corresponding entry in merge_cp_p. Index map
1581 // entries are only created for entries in scratch_cp that occupy a
1582 // different location in merged_cp_p.
1583 bool VM_RedefineClasses::merge_constant_pools(const constantPoolHandle& old_cp,
1584 const constantPoolHandle& scratch_cp, constantPoolHandle& merge_cp_p,
1585 int& merge_cp_length_p, TRAPS) {
1586
1587 // Worst case we need old_cp->length() + scratch_cp()->length(),
1588 // but the caller might be smart so make sure we have at least
1589 // the minimum.
1590 if (merge_cp_p->length() < old_cp->length()) {
1591 assert(false, "merge area too small");
1592 return false; // robustness
1593 }
1594
1595 log_info(redefine, class, constantpool)("old_cp_len=%d, scratch_cp_len=%d", old_cp->length(), scratch_cp->length());
1596
1597 {
1598 // Pass 0:
1599 // The old_cp is copied to *merge_cp_p; this means that any code
1600 // using old_cp does not have to change. This work looks like a
1601 // perfect fit for ConstantPool*::copy_cp_to(), but we need to
1602 // handle one special case:
1603 // - revert JVM_CONSTANT_Class to JVM_CONSTANT_UnresolvedClass
1604 // This will make verification happy.
1605
1606 int old_i; // index into old_cp
1607
1608 // index zero (0) is not used in constantPools
1609 for (old_i = 1; old_i < old_cp->length(); old_i++) {
1610 // leave debugging crumb
1611 jbyte old_tag = old_cp->tag_at(old_i).value();
1612 switch (old_tag) {
1613 case JVM_CONSTANT_Class:
1614 case JVM_CONSTANT_UnresolvedClass:
1615 // revert the copy to JVM_CONSTANT_UnresolvedClass
1616 // May be resolving while calling this so do the same for
1617 // JVM_CONSTANT_UnresolvedClass (klass_name_at() deals with transition)
1618 merge_cp_p->temp_unresolved_klass_at_put(old_i,
1619 old_cp->klass_name_index_at(old_i));
1620 break;
1621
1622 case JVM_CONSTANT_Double:
1623 case JVM_CONSTANT_Long:
1624 // just copy the entry to merge_cp_p, but double and long take
1625 // two constant pool entries
1626 ConstantPool::copy_entry_to(old_cp, old_i, merge_cp_p, old_i);
1627 old_i++;
1628 break;
1629
1630 default:
1631 // just copy the entry to merge_cp_p
1632 ConstantPool::copy_entry_to(old_cp, old_i, merge_cp_p, old_i);
1633 break;
1634 }
1635 } // end for each old_cp entry
1636
1637 ConstantPool::copy_operands(old_cp, merge_cp_p, CHECK_false);
1638 merge_cp_p->extend_operands(scratch_cp, CHECK_false);
1639
1640 // We don't need to sanity check that *merge_cp_length_p is within
1641 // *merge_cp_p bounds since we have the minimum on-entry check above.
1642 merge_cp_length_p = old_i;
1643 }
1644
1645 // merge_cp_len should be the same as old_cp->length() at this point
1646 // so this trace message is really a "warm-and-breathing" message.
1647 log_debug(redefine, class, constantpool)("after pass 0: merge_cp_len=%d", merge_cp_length_p);
1648
1649 int scratch_i; // index into scratch_cp
1650 {
1651 // Pass 1a:
1652 // Compare scratch_cp entries to the old_cp entries that we have
1653 // already copied to *merge_cp_p. In this pass, we are eliminating
1654 // exact duplicates (matching entry at same index) so we only
1655 // compare entries in the common indice range.
1656 int increment = 1;
1657 int pass1a_length = MIN2(old_cp->length(), scratch_cp->length());
1658 for (scratch_i = 1; scratch_i < pass1a_length; scratch_i += increment) {
1659 switch (scratch_cp->tag_at(scratch_i).value()) {
1660 case JVM_CONSTANT_Double:
1661 case JVM_CONSTANT_Long:
1662 // double and long take two constant pool entries
1663 increment = 2;
1664 break;
1665
1666 default:
1667 increment = 1;
1668 break;
1669 }
1670
1671 bool match = scratch_cp->compare_entry_to(scratch_i, merge_cp_p, scratch_i);
1672 if (match) {
1673 // found a match at the same index so nothing more to do
1674 continue;
1675 }
1676
1677 int found_i = scratch_cp->find_matching_entry(scratch_i, merge_cp_p);
1678 if (found_i != 0) {
1679 guarantee(found_i != scratch_i,
1680 "compare_entry_to() and find_matching_entry() do not agree");
1681
1682 // Found a matching entry somewhere else in *merge_cp_p so
1683 // just need a mapping entry.
1684 map_index(scratch_cp, scratch_i, found_i);
1685 continue;
1686 }
1687
1688 // No match found so we have to append this entry and any unique
1689 // referenced entries to merge_cp_p.
1690 append_entry(scratch_cp, scratch_i, &merge_cp_p, &merge_cp_length_p);
1691 }
1692 }
1693
1694 log_debug(redefine, class, constantpool)
1695 ("after pass 1a: merge_cp_len=%d, scratch_i=%d, index_map_len=%d",
1696 merge_cp_length_p, scratch_i, _index_map_count);
1697
1698 if (scratch_i < scratch_cp->length()) {
1699 // Pass 1b:
1700 // old_cp is smaller than scratch_cp so there are entries in
1701 // scratch_cp that we have not yet processed. We take care of
1702 // those now.
1703 int increment = 1;
1704 for (; scratch_i < scratch_cp->length(); scratch_i += increment) {
1705 switch (scratch_cp->tag_at(scratch_i).value()) {
1706 case JVM_CONSTANT_Double:
1707 case JVM_CONSTANT_Long:
1708 // double and long take two constant pool entries
1709 increment = 2;
1710 break;
1711
1712 default:
1713 increment = 1;
1714 break;
1715 }
1716
1717 int found_i =
1718 scratch_cp->find_matching_entry(scratch_i, merge_cp_p);
1719 if (found_i != 0) {
1720 // Found a matching entry somewhere else in merge_cp_p so
1721 // just need a mapping entry.
1722 map_index(scratch_cp, scratch_i, found_i);
1723 continue;
1724 }
1725
1726 // No match found so we have to append this entry and any unique
1727 // referenced entries to merge_cp_p.
1728 append_entry(scratch_cp, scratch_i, &merge_cp_p, &merge_cp_length_p);
1729 }
1730
1731 log_debug(redefine, class, constantpool)
1732 ("after pass 1b: merge_cp_len=%d, scratch_i=%d, index_map_len=%d",
1733 merge_cp_length_p, scratch_i, _index_map_count);
1734 }
1735 finalize_operands_merge(merge_cp_p, CHECK_false);
1736
1737 return true;
1738 } // end merge_constant_pools()
1739
1740
1741 // Scoped object to clean up the constant pool(s) created for merging
1742 class MergeCPCleaner {
1743 ClassLoaderData* _loader_data;
1744 ConstantPool* _cp;
1745 ConstantPool* _scratch_cp;
1746 public:
1747 MergeCPCleaner(ClassLoaderData* loader_data, ConstantPool* merge_cp) :
1748 _loader_data(loader_data), _cp(merge_cp), _scratch_cp(nullptr) {}
1749 ~MergeCPCleaner() {
1750 _loader_data->add_to_deallocate_list(_cp);
1751 if (_scratch_cp != nullptr) {
1752 _loader_data->add_to_deallocate_list(_scratch_cp);
1753 }
1754 }
1755 void add_scratch_cp(ConstantPool* scratch_cp) { _scratch_cp = scratch_cp; }
1756 };
1757
1758 // Merge constant pools between the_class and scratch_class and
1759 // potentially rewrite bytecodes in scratch_class to use the merged
1760 // constant pool.
1761 jvmtiError VM_RedefineClasses::merge_cp_and_rewrite(
1762 InstanceKlass* the_class, InstanceKlass* scratch_class,
1763 TRAPS) {
1764 // worst case merged constant pool length is old and new combined
1765 int merge_cp_length = the_class->constants()->length()
1766 + scratch_class->constants()->length();
1767
1768 // Constant pools are not easily reused so we allocate a new one
1769 // each time.
1770 // merge_cp is created unsafe for concurrent GC processing. It
1771 // should be marked safe before discarding it. Even though
1772 // garbage, if it crosses a card boundary, it may be scanned
1773 // in order to find the start of the first complete object on the card.
1774 ClassLoaderData* loader_data = the_class->class_loader_data();
1775 ConstantPool* merge_cp_oop =
1776 ConstantPool::allocate(loader_data,
1777 merge_cp_length,
1778 CHECK_(JVMTI_ERROR_OUT_OF_MEMORY));
1779 MergeCPCleaner cp_cleaner(loader_data, merge_cp_oop);
1780
1781 HandleMark hm(THREAD); // make sure handles are cleared before
1782 // MergeCPCleaner clears out merge_cp_oop
1783 constantPoolHandle merge_cp(THREAD, merge_cp_oop);
1784
1785 // Get constants() from the old class because it could have been rewritten
1786 // while we were at a safepoint allocating a new constant pool.
1787 constantPoolHandle old_cp(THREAD, the_class->constants());
1788 constantPoolHandle scratch_cp(THREAD, scratch_class->constants());
1789
1790 // If the length changed, the class was redefined out from under us. Return
1791 // an error.
1792 if (merge_cp_length != the_class->constants()->length()
1793 + scratch_class->constants()->length()) {
1794 return JVMTI_ERROR_INTERNAL;
1795 }
1796
1797 // Update the version number of the constant pools (may keep scratch_cp)
1798 merge_cp->increment_and_save_version(old_cp->version());
1799 scratch_cp->increment_and_save_version(old_cp->version());
1800
1801 ResourceMark rm(THREAD);
1802 _index_map_count = 0;
1803 _index_map_p = new intArray(scratch_cp->length(), scratch_cp->length(), -1);
1804
1805 _operands_cur_length = ConstantPool::operand_array_length(old_cp->operands());
1806 _operands_index_map_count = 0;
1807 int operands_index_map_len = ConstantPool::operand_array_length(scratch_cp->operands());
1808 _operands_index_map_p = new intArray(operands_index_map_len, operands_index_map_len, -1);
1809
1810 // reference to the cp holder is needed for copy_operands()
1811 merge_cp->set_pool_holder(scratch_class);
1812 bool result = merge_constant_pools(old_cp, scratch_cp, merge_cp,
1813 merge_cp_length, THREAD);
1814 merge_cp->set_pool_holder(nullptr);
1815
1816 if (!result) {
1817 // The merge can fail due to memory allocation failure or due
1818 // to robustness checks.
1819 return JVMTI_ERROR_INTERNAL;
1820 }
1821
1822 // ensure merged constant pool size does not overflow u2
1823 if (merge_cp_length > 0xFFFF) {
1824 log_warning(redefine, class, constantpool)("Merged constant pool overflow: %d entries", merge_cp_length);
1825 return JVMTI_ERROR_INTERNAL;
1826 }
1827
1828 // Set dynamic constants attribute from the original CP.
1829 if (old_cp->has_dynamic_constant()) {
1830 scratch_cp->set_has_dynamic_constant();
1831 }
1832
1833 log_info(redefine, class, constantpool)("merge_cp_len=%d, index_map_len=%d", merge_cp_length, _index_map_count);
1834
1835 if (_index_map_count == 0) {
1836 // there is nothing to map between the new and merged constant pools
1837
1838 // Copy attributes from scratch_cp to merge_cp
1839 merge_cp->copy_fields(scratch_cp());
1840
1841 if (old_cp->length() == scratch_cp->length()) {
1842 // The old and new constant pools are the same length and the
1843 // index map is empty. This means that the three constant pools
1844 // are equivalent (but not the same). Unfortunately, the new
1845 // constant pool has not gone through link resolution nor have
1846 // the new class bytecodes gone through constant pool cache
1847 // rewriting so we can't use the old constant pool with the new
1848 // class.
1849
1850 // toss the merged constant pool at return
1851 } else if (old_cp->length() < scratch_cp->length()) {
1852 // The old constant pool has fewer entries than the new constant
1853 // pool and the index map is empty. This means the new constant
1854 // pool is a superset of the old constant pool. However, the old
1855 // class bytecodes have already gone through constant pool cache
1856 // rewriting so we can't use the new constant pool with the old
1857 // class.
1858
1859 // toss the merged constant pool at return
1860 } else {
1861 // The old constant pool has more entries than the new constant
1862 // pool and the index map is empty. This means that both the old
1863 // and merged constant pools are supersets of the new constant
1864 // pool.
1865
1866 // Replace the new constant pool with a shrunken copy of the
1867 // merged constant pool
1868 set_new_constant_pool(loader_data, scratch_class, merge_cp, merge_cp_length,
1869 CHECK_(JVMTI_ERROR_OUT_OF_MEMORY));
1870 // The new constant pool replaces scratch_cp so have cleaner clean it up.
1871 // It can't be cleaned up while there are handles to it.
1872 cp_cleaner.add_scratch_cp(scratch_cp());
1873 }
1874 } else {
1875 if (log_is_enabled(Trace, redefine, class, constantpool)) {
1876 // don't want to loop unless we are tracing
1877 int count = 0;
1878 for (int i = 1; i < _index_map_p->length(); i++) {
1879 int value = _index_map_p->at(i);
1880
1881 if (value != -1) {
1882 log_trace(redefine, class, constantpool)("index_map[%d]: old=%d new=%d", count, i, value);
1883 count++;
1884 }
1885 }
1886 }
1887
1888 // We have entries mapped between the new and merged constant pools
1889 // so we have to rewrite some constant pool references.
1890 if (!rewrite_cp_refs(scratch_class)) {
1891 return JVMTI_ERROR_INTERNAL;
1892 }
1893
1894 // Copy attributes from scratch_cp to merge_cp (should be done after rewrite_cp_refs())
1895 merge_cp->copy_fields(scratch_cp());
1896
1897 // Replace the new constant pool with a shrunken copy of the
1898 // merged constant pool so now the rewritten bytecodes have
1899 // valid references; the previous new constant pool will get
1900 // GCed.
1901 set_new_constant_pool(loader_data, scratch_class, merge_cp, merge_cp_length,
1902 CHECK_(JVMTI_ERROR_OUT_OF_MEMORY));
1903 // The new constant pool replaces scratch_cp so have cleaner clean it up.
1904 // It can't be cleaned up while there are handles to it.
1905 cp_cleaner.add_scratch_cp(scratch_cp());
1906 }
1907
1908 return JVMTI_ERROR_NONE;
1909 } // end merge_cp_and_rewrite()
1910
1911
1912 // Rewrite constant pool references in klass scratch_class.
1913 bool VM_RedefineClasses::rewrite_cp_refs(InstanceKlass* scratch_class) {
1914
1915 // rewrite constant pool references in the nest attributes:
1916 if (!rewrite_cp_refs_in_nest_attributes(scratch_class)) {
1917 // propagate failure back to caller
1918 return false;
1919 }
1920
1921 // rewrite constant pool references in the Record attribute:
1922 if (!rewrite_cp_refs_in_record_attribute(scratch_class)) {
1923 // propagate failure back to caller
1924 return false;
1925 }
1926
1927 // rewrite constant pool references in the PermittedSubclasses attribute:
1928 if (!rewrite_cp_refs_in_permitted_subclasses_attribute(scratch_class)) {
1929 // propagate failure back to caller
1930 return false;
1931 }
1932
1933 // rewrite constant pool references in the methods:
1934 if (!rewrite_cp_refs_in_methods(scratch_class)) {
1935 // propagate failure back to caller
1936 return false;
1937 }
1938
1939 // rewrite constant pool references in the class_annotations:
1940 if (!rewrite_cp_refs_in_class_annotations(scratch_class)) {
1941 // propagate failure back to caller
1942 return false;
1943 }
1944
1945 // rewrite constant pool references in the fields_annotations:
1946 if (!rewrite_cp_refs_in_fields_annotations(scratch_class)) {
1947 // propagate failure back to caller
1948 return false;
1949 }
1950
1951 // rewrite constant pool references in the methods_annotations:
1952 if (!rewrite_cp_refs_in_methods_annotations(scratch_class)) {
1953 // propagate failure back to caller
1954 return false;
1955 }
1956
1957 // rewrite constant pool references in the methods_parameter_annotations:
1958 if (!rewrite_cp_refs_in_methods_parameter_annotations(scratch_class)) {
1959 // propagate failure back to caller
1960 return false;
1961 }
1962
1963 // rewrite constant pool references in the methods_default_annotations:
1964 if (!rewrite_cp_refs_in_methods_default_annotations(scratch_class)) {
1965 // propagate failure back to caller
1966 return false;
1967 }
1968
1969 // rewrite constant pool references in the class_type_annotations:
1970 if (!rewrite_cp_refs_in_class_type_annotations(scratch_class)) {
1971 // propagate failure back to caller
1972 return false;
1973 }
1974
1975 // rewrite constant pool references in the fields_type_annotations:
1976 if (!rewrite_cp_refs_in_fields_type_annotations(scratch_class)) {
1977 // propagate failure back to caller
1978 return false;
1979 }
1980
1981 // rewrite constant pool references in the methods_type_annotations:
1982 if (!rewrite_cp_refs_in_methods_type_annotations(scratch_class)) {
1983 // propagate failure back to caller
1984 return false;
1985 }
1986
1987 // There can be type annotations in the Code part of a method_info attribute.
1988 // These annotations are not accessible, even by reflection.
1989 // Currently they are not even parsed by the ClassFileParser.
1990 // If runtime access is added they will also need to be rewritten.
1991
1992 // rewrite source file name index:
1993 u2 source_file_name_idx = scratch_class->source_file_name_index();
1994 if (source_file_name_idx != 0) {
1995 u2 new_source_file_name_idx = find_new_index(source_file_name_idx);
1996 if (new_source_file_name_idx != 0) {
1997 scratch_class->set_source_file_name_index(new_source_file_name_idx);
1998 }
1999 }
2000
2001 // rewrite class generic signature index:
2002 u2 generic_signature_index = scratch_class->generic_signature_index();
2003 if (generic_signature_index != 0) {
2004 u2 new_generic_signature_index = find_new_index(generic_signature_index);
2005 if (new_generic_signature_index != 0) {
2006 scratch_class->set_generic_signature_index(new_generic_signature_index);
2007 }
2008 }
2009
2010 return true;
2011 } // end rewrite_cp_refs()
2012
2013 // Rewrite constant pool references in the NestHost and NestMembers attributes.
2014 bool VM_RedefineClasses::rewrite_cp_refs_in_nest_attributes(
2015 InstanceKlass* scratch_class) {
2016
2017 u2 cp_index = scratch_class->nest_host_index();
2018 if (cp_index != 0) {
2019 scratch_class->set_nest_host_index(find_new_index(cp_index));
2020 }
2021 Array<u2>* nest_members = scratch_class->nest_members();
2022 for (int i = 0; i < nest_members->length(); i++) {
2023 u2 cp_index = nest_members->at(i);
2024 nest_members->at_put(i, find_new_index(cp_index));
2025 }
2026 return true;
2027 }
2028
2029 // Rewrite constant pool references in the Record attribute.
2030 bool VM_RedefineClasses::rewrite_cp_refs_in_record_attribute(InstanceKlass* scratch_class) {
2031 Array<RecordComponent*>* components = scratch_class->record_components();
2032 if (components != nullptr) {
2033 for (int i = 0; i < components->length(); i++) {
2034 RecordComponent* component = components->at(i);
2035 u2 cp_index = component->name_index();
2036 component->set_name_index(find_new_index(cp_index));
2037 cp_index = component->descriptor_index();
2038 component->set_descriptor_index(find_new_index(cp_index));
2039 cp_index = component->generic_signature_index();
2040 if (cp_index != 0) {
2041 component->set_generic_signature_index(find_new_index(cp_index));
2042 }
2043
2044 AnnotationArray* annotations = component->annotations();
2045 if (annotations != nullptr && annotations->length() != 0) {
2046 int byte_i = 0; // byte index into annotations
2047 if (!rewrite_cp_refs_in_annotations_typeArray(annotations, byte_i)) {
2048 log_debug(redefine, class, annotation)("bad record_component_annotations at %d", i);
2049 // propagate failure back to caller
2050 return false;
2051 }
2052 }
2053
2054 AnnotationArray* type_annotations = component->type_annotations();
2055 if (type_annotations != nullptr && type_annotations->length() != 0) {
2056 int byte_i = 0; // byte index into annotations
2057 if (!rewrite_cp_refs_in_annotations_typeArray(type_annotations, byte_i)) {
2058 log_debug(redefine, class, annotation)("bad record_component_type_annotations at %d", i);
2059 // propagate failure back to caller
2060 return false;
2061 }
2062 }
2063 }
2064 }
2065 return true;
2066 }
2067
2068 // Rewrite constant pool references in the PermittedSubclasses attribute.
2069 bool VM_RedefineClasses::rewrite_cp_refs_in_permitted_subclasses_attribute(
2070 InstanceKlass* scratch_class) {
2071
2072 Array<u2>* permitted_subclasses = scratch_class->permitted_subclasses();
2073 assert(permitted_subclasses != nullptr, "unexpected null permitted_subclasses");
2074 for (int i = 0; i < permitted_subclasses->length(); i++) {
2075 u2 cp_index = permitted_subclasses->at(i);
2076 permitted_subclasses->at_put(i, find_new_index(cp_index));
2077 }
2078 return true;
2079 }
2080
2081 // Rewrite constant pool references in the methods.
2082 bool VM_RedefineClasses::rewrite_cp_refs_in_methods(InstanceKlass* scratch_class) {
2083
2084 Array<Method*>* methods = scratch_class->methods();
2085
2086 if (methods == nullptr || methods->length() == 0) {
2087 // no methods so nothing to do
2088 return true;
2089 }
2090
2091 JavaThread* THREAD = JavaThread::current(); // For exception macros.
2092 ExceptionMark em(THREAD);
2093
2094 // rewrite constant pool references in the methods:
2095 for (int i = methods->length() - 1; i >= 0; i--) {
2096 methodHandle method(THREAD, methods->at(i));
2097 methodHandle new_method;
2098 rewrite_cp_refs_in_method(method, &new_method, THREAD);
2099 if (!new_method.is_null()) {
2100 // the method has been replaced so save the new method version
2101 // even in the case of an exception. original method is on the
2102 // deallocation list.
2103 methods->at_put(i, new_method());
2104 }
2105 if (HAS_PENDING_EXCEPTION) {
2106 Symbol* ex_name = PENDING_EXCEPTION->klass()->name();
2107 log_info(redefine, class, load, exceptions)("rewrite_cp_refs_in_method exception: '%s'", ex_name->as_C_string());
2108 // Need to clear pending exception here as the super caller sets
2109 // the JVMTI_ERROR_INTERNAL if the returned value is false.
2110 CLEAR_PENDING_EXCEPTION;
2111 return false;
2112 }
2113 }
2114
2115 return true;
2116 }
2117
2118
2119 // Rewrite constant pool references in the specific method. This code
2120 // was adapted from Rewriter::rewrite_method().
2121 void VM_RedefineClasses::rewrite_cp_refs_in_method(methodHandle method,
2122 methodHandle *new_method_p, TRAPS) {
2123
2124 *new_method_p = methodHandle(); // default is no new method
2125
2126 // We cache a pointer to the bytecodes here in code_base. If GC
2127 // moves the Method*, then the bytecodes will also move which
2128 // will likely cause a crash. We create a NoSafepointVerifier
2129 // object to detect whether we pass a possible safepoint in this
2130 // code block.
2131 NoSafepointVerifier nsv;
2132
2133 // Bytecodes and their length
2134 address code_base = method->code_base();
2135 int code_length = method->code_size();
2136
2137 int bc_length;
2138 for (int bci = 0; bci < code_length; bci += bc_length) {
2139 address bcp = code_base + bci;
2140 Bytecodes::Code c = (Bytecodes::Code)(*bcp);
2141
2142 bc_length = Bytecodes::length_for(c);
2143 if (bc_length == 0) {
2144 // More complicated bytecodes report a length of zero so
2145 // we have to try again a slightly different way.
2146 bc_length = Bytecodes::length_at(method(), bcp);
2147 }
2148
2149 assert(bc_length != 0, "impossible bytecode length");
2150
2151 switch (c) {
2152 case Bytecodes::_ldc:
2153 {
2154 u1 cp_index = *(bcp + 1);
2155 u2 new_index = find_new_index(cp_index);
2156
2157 if (StressLdcRewrite && new_index == 0) {
2158 // If we are stressing ldc -> ldc_w rewriting, then we
2159 // always need a new_index value.
2160 new_index = cp_index;
2161 }
2162 if (new_index != 0) {
2163 // the original index is mapped so we have more work to do
2164 if (!StressLdcRewrite && new_index <= max_jubyte) {
2165 // The new value can still use ldc instead of ldc_w
2166 // unless we are trying to stress ldc -> ldc_w rewriting
2167 log_trace(redefine, class, constantpool)
2168 ("%s@" INTPTR_FORMAT " old=%d, new=%d", Bytecodes::name(c), p2i(bcp), cp_index, new_index);
2169 // We checked that new_index fits in a u1 so this cast is safe
2170 *(bcp + 1) = (u1)new_index;
2171 } else {
2172 log_trace(redefine, class, constantpool)
2173 ("%s->ldc_w@" INTPTR_FORMAT " old=%d, new=%d", Bytecodes::name(c), p2i(bcp), cp_index, new_index);
2174 // the new value needs ldc_w instead of ldc
2175 u_char inst_buffer[4]; // max instruction size is 4 bytes
2176 bcp = (address)inst_buffer;
2177 // construct new instruction sequence
2178 *bcp = Bytecodes::_ldc_w;
2179 bcp++;
2180 // Rewriter::rewrite_method() does not rewrite ldc -> ldc_w.
2181 // See comment below for difference between put_Java_u2()
2182 // and put_native_u2().
2183 Bytes::put_Java_u2(bcp, new_index);
2184
2185 Relocator rc(method, nullptr /* no RelocatorListener needed */);
2186 methodHandle m;
2187 {
2188 PauseNoSafepointVerifier pnsv(&nsv);
2189
2190 // ldc is 2 bytes and ldc_w is 3 bytes
2191 m = rc.insert_space_at(bci, 3, inst_buffer, CHECK);
2192 }
2193
2194 // return the new method so that the caller can update
2195 // the containing class
2196 *new_method_p = method = m;
2197 // switch our bytecode processing loop from the old method
2198 // to the new method
2199 code_base = method->code_base();
2200 code_length = method->code_size();
2201 bcp = code_base + bci;
2202 c = (Bytecodes::Code)(*bcp);
2203 bc_length = Bytecodes::length_for(c);
2204 assert(bc_length != 0, "sanity check");
2205 } // end we need ldc_w instead of ldc
2206 } // end if there is a mapped index
2207 } break;
2208
2209 // these bytecodes have a two-byte constant pool index
2210 case Bytecodes::_anewarray : // fall through
2211 case Bytecodes::_checkcast : // fall through
2212 case Bytecodes::_getfield : // fall through
2213 case Bytecodes::_getstatic : // fall through
2214 case Bytecodes::_instanceof : // fall through
2215 case Bytecodes::_invokedynamic : // fall through
2216 case Bytecodes::_invokeinterface: // fall through
2217 case Bytecodes::_invokespecial : // fall through
2218 case Bytecodes::_invokestatic : // fall through
2219 case Bytecodes::_invokevirtual : // fall through
2220 case Bytecodes::_ldc_w : // fall through
2221 case Bytecodes::_ldc2_w : // fall through
2222 case Bytecodes::_multianewarray : // fall through
2223 case Bytecodes::_new : // fall through
2224 case Bytecodes::_putfield : // fall through
2225 case Bytecodes::_putstatic :
2226 {
2227 address p = bcp + 1;
2228 int cp_index = Bytes::get_Java_u2(p);
2229 u2 new_index = find_new_index(cp_index);
2230 if (new_index != 0) {
2231 // the original index is mapped so update w/ new value
2232 log_trace(redefine, class, constantpool)
2233 ("%s@" INTPTR_FORMAT " old=%d, new=%d", Bytecodes::name(c),p2i(bcp), cp_index, new_index);
2234 // Rewriter::rewrite_method() uses put_native_u2() in this
2235 // situation because it is reusing the constant pool index
2236 // location for a native index into the ConstantPoolCache.
2237 // Since we are updating the constant pool index prior to
2238 // verification and ConstantPoolCache initialization, we
2239 // need to keep the new index in Java byte order.
2240 Bytes::put_Java_u2(p, new_index);
2241 }
2242 } break;
2243 default:
2244 break;
2245 }
2246 } // end for each bytecode
2247 } // end rewrite_cp_refs_in_method()
2248
2249
2250 // Rewrite constant pool references in the class_annotations field.
2251 bool VM_RedefineClasses::rewrite_cp_refs_in_class_annotations(InstanceKlass* scratch_class) {
2252
2253 AnnotationArray* class_annotations = scratch_class->class_annotations();
2254 if (class_annotations == nullptr || class_annotations->length() == 0) {
2255 // no class_annotations so nothing to do
2256 return true;
2257 }
2258
2259 log_debug(redefine, class, annotation)("class_annotations length=%d", class_annotations->length());
2260
2261 int byte_i = 0; // byte index into class_annotations
2262 return rewrite_cp_refs_in_annotations_typeArray(class_annotations, byte_i);
2263 }
2264
2265
2266 // Rewrite constant pool references in an annotations typeArray. This
2267 // "structure" is adapted from the RuntimeVisibleAnnotations_attribute
2268 // that is described in section 4.8.15 of the 2nd-edition of the VM spec:
2269 //
2270 // annotations_typeArray {
2271 // u2 num_annotations;
2272 // annotation annotations[num_annotations];
2273 // }
2274 //
2275 bool VM_RedefineClasses::rewrite_cp_refs_in_annotations_typeArray(
2276 AnnotationArray* annotations_typeArray, int &byte_i_ref) {
2277
2278 if ((byte_i_ref + 2) > annotations_typeArray->length()) {
2279 // not enough room for num_annotations field
2280 log_debug(redefine, class, annotation)("length() is too small for num_annotations field");
2281 return false;
2282 }
2283
2284 u2 num_annotations = Bytes::get_Java_u2((address)
2285 annotations_typeArray->adr_at(byte_i_ref));
2286 byte_i_ref += 2;
2287
2288 log_debug(redefine, class, annotation)("num_annotations=%d", num_annotations);
2289
2290 int calc_num_annotations = 0;
2291 for (; calc_num_annotations < num_annotations; calc_num_annotations++) {
2292 if (!rewrite_cp_refs_in_annotation_struct(annotations_typeArray, byte_i_ref)) {
2293 log_debug(redefine, class, annotation)("bad annotation_struct at %d", calc_num_annotations);
2294 // propagate failure back to caller
2295 return false;
2296 }
2297 }
2298 assert(num_annotations == calc_num_annotations, "sanity check");
2299
2300 return true;
2301 } // end rewrite_cp_refs_in_annotations_typeArray()
2302
2303
2304 // Rewrite constant pool references in the annotation struct portion of
2305 // an annotations_typeArray. This "structure" is from section 4.8.15 of
2306 // the 2nd-edition of the VM spec:
2307 //
2308 // struct annotation {
2309 // u2 type_index;
2310 // u2 num_element_value_pairs;
2311 // {
2312 // u2 element_name_index;
2313 // element_value value;
2314 // } element_value_pairs[num_element_value_pairs];
2315 // }
2316 //
2317 bool VM_RedefineClasses::rewrite_cp_refs_in_annotation_struct(
2318 AnnotationArray* annotations_typeArray, int &byte_i_ref) {
2319 if ((byte_i_ref + 2 + 2) > annotations_typeArray->length()) {
2320 // not enough room for smallest annotation_struct
2321 log_debug(redefine, class, annotation)("length() is too small for annotation_struct");
2322 return false;
2323 }
2324
2325 u2 type_index = rewrite_cp_ref_in_annotation_data(annotations_typeArray,
2326 byte_i_ref, "type_index");
2327
2328 u2 num_element_value_pairs = Bytes::get_Java_u2((address)
2329 annotations_typeArray->adr_at(byte_i_ref));
2330 byte_i_ref += 2;
2331
2332 log_debug(redefine, class, annotation)
2333 ("type_index=%d num_element_value_pairs=%d", type_index, num_element_value_pairs);
2334
2335 int calc_num_element_value_pairs = 0;
2336 for (; calc_num_element_value_pairs < num_element_value_pairs;
2337 calc_num_element_value_pairs++) {
2338 if ((byte_i_ref + 2) > annotations_typeArray->length()) {
2339 // not enough room for another element_name_index, let alone
2340 // the rest of another component
2341 log_debug(redefine, class, annotation)("length() is too small for element_name_index");
2342 return false;
2343 }
2344
2345 u2 element_name_index = rewrite_cp_ref_in_annotation_data(
2346 annotations_typeArray, byte_i_ref,
2347 "element_name_index");
2348
2349 log_debug(redefine, class, annotation)("element_name_index=%d", element_name_index);
2350
2351 if (!rewrite_cp_refs_in_element_value(annotations_typeArray, byte_i_ref)) {
2352 log_debug(redefine, class, annotation)("bad element_value at %d", calc_num_element_value_pairs);
2353 // propagate failure back to caller
2354 return false;
2355 }
2356 } // end for each component
2357 assert(num_element_value_pairs == calc_num_element_value_pairs,
2358 "sanity check");
2359
2360 return true;
2361 } // end rewrite_cp_refs_in_annotation_struct()
2362
2363
2364 // Rewrite a constant pool reference at the current position in
2365 // annotations_typeArray if needed. Returns the original constant
2366 // pool reference if a rewrite was not needed or the new constant
2367 // pool reference if a rewrite was needed.
2368 u2 VM_RedefineClasses::rewrite_cp_ref_in_annotation_data(
2369 AnnotationArray* annotations_typeArray, int &byte_i_ref,
2370 const char * trace_mesg) {
2371
2372 address cp_index_addr = (address)
2373 annotations_typeArray->adr_at(byte_i_ref);
2374 u2 old_cp_index = Bytes::get_Java_u2(cp_index_addr);
2375 u2 new_cp_index = find_new_index(old_cp_index);
2376 if (new_cp_index != 0) {
2377 log_debug(redefine, class, annotation)("mapped old %s=%d", trace_mesg, old_cp_index);
2378 Bytes::put_Java_u2(cp_index_addr, new_cp_index);
2379 old_cp_index = new_cp_index;
2380 }
2381 byte_i_ref += 2;
2382 return old_cp_index;
2383 }
2384
2385
2386 // Rewrite constant pool references in the element_value portion of an
2387 // annotations_typeArray. This "structure" is from section 4.8.15.1 of
2388 // the 2nd-edition of the VM spec:
2389 //
2390 // struct element_value {
2391 // u1 tag;
2392 // union {
2393 // u2 const_value_index;
2394 // {
2395 // u2 type_name_index;
2396 // u2 const_name_index;
2397 // } enum_const_value;
2398 // u2 class_info_index;
2399 // annotation annotation_value;
2400 // struct {
2401 // u2 num_values;
2402 // element_value values[num_values];
2403 // } array_value;
2404 // } value;
2405 // }
2406 //
2407 bool VM_RedefineClasses::rewrite_cp_refs_in_element_value(
2408 AnnotationArray* annotations_typeArray, int &byte_i_ref) {
2409
2410 if ((byte_i_ref + 1) > annotations_typeArray->length()) {
2411 // not enough room for a tag let alone the rest of an element_value
2412 log_debug(redefine, class, annotation)("length() is too small for a tag");
2413 return false;
2414 }
2415
2416 u1 tag = annotations_typeArray->at(byte_i_ref);
2417 byte_i_ref++;
2418 log_debug(redefine, class, annotation)("tag='%c'", tag);
2419
2420 switch (tag) {
2421 // These BaseType tag values are from Table 4.2 in VM spec:
2422 case JVM_SIGNATURE_BYTE:
2423 case JVM_SIGNATURE_CHAR:
2424 case JVM_SIGNATURE_DOUBLE:
2425 case JVM_SIGNATURE_FLOAT:
2426 case JVM_SIGNATURE_INT:
2427 case JVM_SIGNATURE_LONG:
2428 case JVM_SIGNATURE_SHORT:
2429 case JVM_SIGNATURE_BOOLEAN:
2430
2431 // The remaining tag values are from Table 4.8 in the 2nd-edition of
2432 // the VM spec:
2433 case 's':
2434 {
2435 // For the above tag values (including the BaseType values),
2436 // value.const_value_index is right union field.
2437
2438 if ((byte_i_ref + 2) > annotations_typeArray->length()) {
2439 // not enough room for a const_value_index
2440 log_debug(redefine, class, annotation)("length() is too small for a const_value_index");
2441 return false;
2442 }
2443
2444 u2 const_value_index = rewrite_cp_ref_in_annotation_data(
2445 annotations_typeArray, byte_i_ref,
2446 "const_value_index");
2447
2448 log_debug(redefine, class, annotation)("const_value_index=%d", const_value_index);
2449 } break;
2450
2451 case 'e':
2452 {
2453 // for the above tag value, value.enum_const_value is right union field
2454
2455 if ((byte_i_ref + 4) > annotations_typeArray->length()) {
2456 // not enough room for a enum_const_value
2457 log_debug(redefine, class, annotation)("length() is too small for a enum_const_value");
2458 return false;
2459 }
2460
2461 u2 type_name_index = rewrite_cp_ref_in_annotation_data(
2462 annotations_typeArray, byte_i_ref,
2463 "type_name_index");
2464
2465 u2 const_name_index = rewrite_cp_ref_in_annotation_data(
2466 annotations_typeArray, byte_i_ref,
2467 "const_name_index");
2468
2469 log_debug(redefine, class, annotation)
2470 ("type_name_index=%d const_name_index=%d", type_name_index, const_name_index);
2471 } break;
2472
2473 case 'c':
2474 {
2475 // for the above tag value, value.class_info_index is right union field
2476
2477 if ((byte_i_ref + 2) > annotations_typeArray->length()) {
2478 // not enough room for a class_info_index
2479 log_debug(redefine, class, annotation)("length() is too small for a class_info_index");
2480 return false;
2481 }
2482
2483 u2 class_info_index = rewrite_cp_ref_in_annotation_data(
2484 annotations_typeArray, byte_i_ref,
2485 "class_info_index");
2486
2487 log_debug(redefine, class, annotation)("class_info_index=%d", class_info_index);
2488 } break;
2489
2490 case '@':
2491 // For the above tag value, value.attr_value is the right union
2492 // field. This is a nested annotation.
2493 if (!rewrite_cp_refs_in_annotation_struct(annotations_typeArray, byte_i_ref)) {
2494 // propagate failure back to caller
2495 return false;
2496 }
2497 break;
2498
2499 case JVM_SIGNATURE_ARRAY:
2500 {
2501 if ((byte_i_ref + 2) > annotations_typeArray->length()) {
2502 // not enough room for a num_values field
2503 log_debug(redefine, class, annotation)("length() is too small for a num_values field");
2504 return false;
2505 }
2506
2507 // For the above tag value, value.array_value is the right union
2508 // field. This is an array of nested element_value.
2509 u2 num_values = Bytes::get_Java_u2((address)
2510 annotations_typeArray->adr_at(byte_i_ref));
2511 byte_i_ref += 2;
2512 log_debug(redefine, class, annotation)("num_values=%d", num_values);
2513
2514 int calc_num_values = 0;
2515 for (; calc_num_values < num_values; calc_num_values++) {
2516 if (!rewrite_cp_refs_in_element_value(annotations_typeArray, byte_i_ref)) {
2517 log_debug(redefine, class, annotation)("bad nested element_value at %d", calc_num_values);
2518 // propagate failure back to caller
2519 return false;
2520 }
2521 }
2522 assert(num_values == calc_num_values, "sanity check");
2523 } break;
2524
2525 default:
2526 log_debug(redefine, class, annotation)("bad tag=0x%x", tag);
2527 return false;
2528 } // end decode tag field
2529
2530 return true;
2531 } // end rewrite_cp_refs_in_element_value()
2532
2533
2534 // Rewrite constant pool references in a fields_annotations field.
2535 bool VM_RedefineClasses::rewrite_cp_refs_in_fields_annotations(
2536 InstanceKlass* scratch_class) {
2537
2538 Array<AnnotationArray*>* fields_annotations = scratch_class->fields_annotations();
2539
2540 if (fields_annotations == nullptr || fields_annotations->length() == 0) {
2541 // no fields_annotations so nothing to do
2542 return true;
2543 }
2544
2545 log_debug(redefine, class, annotation)("fields_annotations length=%d", fields_annotations->length());
2546
2547 for (int i = 0; i < fields_annotations->length(); i++) {
2548 AnnotationArray* field_annotations = fields_annotations->at(i);
2549 if (field_annotations == nullptr || field_annotations->length() == 0) {
2550 // this field does not have any annotations so skip it
2551 continue;
2552 }
2553
2554 int byte_i = 0; // byte index into field_annotations
2555 if (!rewrite_cp_refs_in_annotations_typeArray(field_annotations, byte_i)) {
2556 log_debug(redefine, class, annotation)("bad field_annotations at %d", i);
2557 // propagate failure back to caller
2558 return false;
2559 }
2560 }
2561
2562 return true;
2563 } // end rewrite_cp_refs_in_fields_annotations()
2564
2565
2566 // Rewrite constant pool references in a methods_annotations field.
2567 bool VM_RedefineClasses::rewrite_cp_refs_in_methods_annotations(
2568 InstanceKlass* scratch_class) {
2569
2570 for (int i = 0; i < scratch_class->methods()->length(); i++) {
2571 Method* m = scratch_class->methods()->at(i);
2572 AnnotationArray* method_annotations = m->constMethod()->method_annotations();
2573
2574 if (method_annotations == nullptr || method_annotations->length() == 0) {
2575 // this method does not have any annotations so skip it
2576 continue;
2577 }
2578
2579 int byte_i = 0; // byte index into method_annotations
2580 if (!rewrite_cp_refs_in_annotations_typeArray(method_annotations, byte_i)) {
2581 log_debug(redefine, class, annotation)("bad method_annotations at %d", i);
2582 // propagate failure back to caller
2583 return false;
2584 }
2585 }
2586
2587 return true;
2588 } // end rewrite_cp_refs_in_methods_annotations()
2589
2590
2591 // Rewrite constant pool references in a methods_parameter_annotations
2592 // field. This "structure" is adapted from the
2593 // RuntimeVisibleParameterAnnotations_attribute described in section
2594 // 4.8.17 of the 2nd-edition of the VM spec:
2595 //
2596 // methods_parameter_annotations_typeArray {
2597 // u1 num_parameters;
2598 // {
2599 // u2 num_annotations;
2600 // annotation annotations[num_annotations];
2601 // } parameter_annotations[num_parameters];
2602 // }
2603 //
2604 bool VM_RedefineClasses::rewrite_cp_refs_in_methods_parameter_annotations(
2605 InstanceKlass* scratch_class) {
2606
2607 for (int i = 0; i < scratch_class->methods()->length(); i++) {
2608 Method* m = scratch_class->methods()->at(i);
2609 AnnotationArray* method_parameter_annotations = m->constMethod()->parameter_annotations();
2610 if (method_parameter_annotations == nullptr
2611 || method_parameter_annotations->length() == 0) {
2612 // this method does not have any parameter annotations so skip it
2613 continue;
2614 }
2615
2616 if (method_parameter_annotations->length() < 1) {
2617 // not enough room for a num_parameters field
2618 log_debug(redefine, class, annotation)("length() is too small for a num_parameters field at %d", i);
2619 return false;
2620 }
2621
2622 int byte_i = 0; // byte index into method_parameter_annotations
2623
2624 u1 num_parameters = method_parameter_annotations->at(byte_i);
2625 byte_i++;
2626
2627 log_debug(redefine, class, annotation)("num_parameters=%d", num_parameters);
2628
2629 int calc_num_parameters = 0;
2630 for (; calc_num_parameters < num_parameters; calc_num_parameters++) {
2631 if (!rewrite_cp_refs_in_annotations_typeArray(method_parameter_annotations, byte_i)) {
2632 log_debug(redefine, class, annotation)("bad method_parameter_annotations at %d", calc_num_parameters);
2633 // propagate failure back to caller
2634 return false;
2635 }
2636 }
2637 assert(num_parameters == calc_num_parameters, "sanity check");
2638 }
2639
2640 return true;
2641 } // end rewrite_cp_refs_in_methods_parameter_annotations()
2642
2643
2644 // Rewrite constant pool references in a methods_default_annotations
2645 // field. This "structure" is adapted from the AnnotationDefault_attribute
2646 // that is described in section 4.8.19 of the 2nd-edition of the VM spec:
2647 //
2648 // methods_default_annotations_typeArray {
2649 // element_value default_value;
2650 // }
2651 //
2652 bool VM_RedefineClasses::rewrite_cp_refs_in_methods_default_annotations(
2653 InstanceKlass* scratch_class) {
2654
2655 for (int i = 0; i < scratch_class->methods()->length(); i++) {
2656 Method* m = scratch_class->methods()->at(i);
2657 AnnotationArray* method_default_annotations = m->constMethod()->default_annotations();
2658 if (method_default_annotations == nullptr
2659 || method_default_annotations->length() == 0) {
2660 // this method does not have any default annotations so skip it
2661 continue;
2662 }
2663
2664 int byte_i = 0; // byte index into method_default_annotations
2665
2666 if (!rewrite_cp_refs_in_element_value(
2667 method_default_annotations, byte_i)) {
2668 log_debug(redefine, class, annotation)("bad default element_value at %d", i);
2669 // propagate failure back to caller
2670 return false;
2671 }
2672 }
2673
2674 return true;
2675 } // end rewrite_cp_refs_in_methods_default_annotations()
2676
2677
2678 // Rewrite constant pool references in a class_type_annotations field.
2679 bool VM_RedefineClasses::rewrite_cp_refs_in_class_type_annotations(
2680 InstanceKlass* scratch_class) {
2681
2682 AnnotationArray* class_type_annotations = scratch_class->class_type_annotations();
2683 if (class_type_annotations == nullptr || class_type_annotations->length() == 0) {
2684 // no class_type_annotations so nothing to do
2685 return true;
2686 }
2687
2688 log_debug(redefine, class, annotation)("class_type_annotations length=%d", class_type_annotations->length());
2689
2690 int byte_i = 0; // byte index into class_type_annotations
2691 return rewrite_cp_refs_in_type_annotations_typeArray(class_type_annotations,
2692 byte_i, "ClassFile");
2693 } // end rewrite_cp_refs_in_class_type_annotations()
2694
2695
2696 // Rewrite constant pool references in a fields_type_annotations field.
2697 bool VM_RedefineClasses::rewrite_cp_refs_in_fields_type_annotations(InstanceKlass* scratch_class) {
2698
2699 Array<AnnotationArray*>* fields_type_annotations = scratch_class->fields_type_annotations();
2700 if (fields_type_annotations == nullptr || fields_type_annotations->length() == 0) {
2701 // no fields_type_annotations so nothing to do
2702 return true;
2703 }
2704
2705 log_debug(redefine, class, annotation)("fields_type_annotations length=%d", fields_type_annotations->length());
2706
2707 for (int i = 0; i < fields_type_annotations->length(); i++) {
2708 AnnotationArray* field_type_annotations = fields_type_annotations->at(i);
2709 if (field_type_annotations == nullptr || field_type_annotations->length() == 0) {
2710 // this field does not have any annotations so skip it
2711 continue;
2712 }
2713
2714 int byte_i = 0; // byte index into field_type_annotations
2715 if (!rewrite_cp_refs_in_type_annotations_typeArray(field_type_annotations,
2716 byte_i, "field_info")) {
2717 log_debug(redefine, class, annotation)("bad field_type_annotations at %d", i);
2718 // propagate failure back to caller
2719 return false;
2720 }
2721 }
2722
2723 return true;
2724 } // end rewrite_cp_refs_in_fields_type_annotations()
2725
2726
2727 // Rewrite constant pool references in a methods_type_annotations field.
2728 bool VM_RedefineClasses::rewrite_cp_refs_in_methods_type_annotations(
2729 InstanceKlass* scratch_class) {
2730
2731 for (int i = 0; i < scratch_class->methods()->length(); i++) {
2732 Method* m = scratch_class->methods()->at(i);
2733 AnnotationArray* method_type_annotations = m->constMethod()->type_annotations();
2734
2735 if (method_type_annotations == nullptr || method_type_annotations->length() == 0) {
2736 // this method does not have any annotations so skip it
2737 continue;
2738 }
2739
2740 log_debug(redefine, class, annotation)("methods type_annotations length=%d", method_type_annotations->length());
2741
2742 int byte_i = 0; // byte index into method_type_annotations
2743 if (!rewrite_cp_refs_in_type_annotations_typeArray(method_type_annotations,
2744 byte_i, "method_info")) {
2745 log_debug(redefine, class, annotation)("bad method_type_annotations at %d", i);
2746 // propagate failure back to caller
2747 return false;
2748 }
2749 }
2750
2751 return true;
2752 } // end rewrite_cp_refs_in_methods_type_annotations()
2753
2754
2755 // Rewrite constant pool references in a type_annotations
2756 // field. This "structure" is adapted from the
2757 // RuntimeVisibleTypeAnnotations_attribute described in
2758 // section 4.7.20 of the Java SE 8 Edition of the VM spec:
2759 //
2760 // type_annotations_typeArray {
2761 // u2 num_annotations;
2762 // type_annotation annotations[num_annotations];
2763 // }
2764 //
2765 bool VM_RedefineClasses::rewrite_cp_refs_in_type_annotations_typeArray(
2766 AnnotationArray* type_annotations_typeArray, int &byte_i_ref,
2767 const char * location_mesg) {
2768
2769 if ((byte_i_ref + 2) > type_annotations_typeArray->length()) {
2770 // not enough room for num_annotations field
2771 log_debug(redefine, class, annotation)("length() is too small for num_annotations field");
2772 return false;
2773 }
2774
2775 u2 num_annotations = Bytes::get_Java_u2((address)
2776 type_annotations_typeArray->adr_at(byte_i_ref));
2777 byte_i_ref += 2;
2778
2779 log_debug(redefine, class, annotation)("num_type_annotations=%d", num_annotations);
2780
2781 int calc_num_annotations = 0;
2782 for (; calc_num_annotations < num_annotations; calc_num_annotations++) {
2783 if (!rewrite_cp_refs_in_type_annotation_struct(type_annotations_typeArray,
2784 byte_i_ref, location_mesg)) {
2785 log_debug(redefine, class, annotation)("bad type_annotation_struct at %d", calc_num_annotations);
2786 // propagate failure back to caller
2787 return false;
2788 }
2789 }
2790 assert(num_annotations == calc_num_annotations, "sanity check");
2791
2792 if (byte_i_ref != type_annotations_typeArray->length()) {
2793 log_debug(redefine, class, annotation)
2794 ("read wrong amount of bytes at end of processing type_annotations_typeArray (%d of %d bytes were read)",
2795 byte_i_ref, type_annotations_typeArray->length());
2796 return false;
2797 }
2798
2799 return true;
2800 } // end rewrite_cp_refs_in_type_annotations_typeArray()
2801
2802
2803 // Rewrite constant pool references in a type_annotation
2804 // field. This "structure" is adapted from the
2805 // RuntimeVisibleTypeAnnotations_attribute described in
2806 // section 4.7.20 of the Java SE 8 Edition of the VM spec:
2807 //
2808 // type_annotation {
2809 // u1 target_type;
2810 // union {
2811 // type_parameter_target;
2812 // supertype_target;
2813 // type_parameter_bound_target;
2814 // empty_target;
2815 // method_formal_parameter_target;
2816 // throws_target;
2817 // localvar_target;
2818 // catch_target;
2819 // offset_target;
2820 // type_argument_target;
2821 // } target_info;
2822 // type_path target_path;
2823 // annotation anno;
2824 // }
2825 //
2826 bool VM_RedefineClasses::rewrite_cp_refs_in_type_annotation_struct(
2827 AnnotationArray* type_annotations_typeArray, int &byte_i_ref,
2828 const char * location_mesg) {
2829
2830 if (!skip_type_annotation_target(type_annotations_typeArray,
2831 byte_i_ref, location_mesg)) {
2832 return false;
2833 }
2834
2835 if (!skip_type_annotation_type_path(type_annotations_typeArray, byte_i_ref)) {
2836 return false;
2837 }
2838
2839 if (!rewrite_cp_refs_in_annotation_struct(type_annotations_typeArray, byte_i_ref)) {
2840 return false;
2841 }
2842
2843 return true;
2844 } // end rewrite_cp_refs_in_type_annotation_struct()
2845
2846
2847 // Read, verify and skip over the target_type and target_info part
2848 // so that rewriting can continue in the later parts of the struct.
2849 //
2850 // u1 target_type;
2851 // union {
2852 // type_parameter_target;
2853 // supertype_target;
2854 // type_parameter_bound_target;
2855 // empty_target;
2856 // method_formal_parameter_target;
2857 // throws_target;
2858 // localvar_target;
2859 // catch_target;
2860 // offset_target;
2861 // type_argument_target;
2862 // } target_info;
2863 //
2864 bool VM_RedefineClasses::skip_type_annotation_target(
2865 AnnotationArray* type_annotations_typeArray, int &byte_i_ref,
2866 const char * location_mesg) {
2867
2868 if ((byte_i_ref + 1) > type_annotations_typeArray->length()) {
2869 // not enough room for a target_type let alone the rest of a type_annotation
2870 log_debug(redefine, class, annotation)("length() is too small for a target_type");
2871 return false;
2872 }
2873
2874 u1 target_type = type_annotations_typeArray->at(byte_i_ref);
2875 byte_i_ref += 1;
2876 log_debug(redefine, class, annotation)("target_type=0x%.2x", target_type);
2877 log_debug(redefine, class, annotation)("location=%s", location_mesg);
2878
2879 // Skip over target_info
2880 switch (target_type) {
2881 case 0x00:
2882 // kind: type parameter declaration of generic class or interface
2883 // location: ClassFile
2884 case 0x01:
2885 // kind: type parameter declaration of generic method or constructor
2886 // location: method_info
2887
2888 {
2889 // struct:
2890 // type_parameter_target {
2891 // u1 type_parameter_index;
2892 // }
2893 //
2894 if ((byte_i_ref + 1) > type_annotations_typeArray->length()) {
2895 log_debug(redefine, class, annotation)("length() is too small for a type_parameter_target");
2896 return false;
2897 }
2898
2899 u1 type_parameter_index = type_annotations_typeArray->at(byte_i_ref);
2900 byte_i_ref += 1;
2901
2902 log_debug(redefine, class, annotation)("type_parameter_target: type_parameter_index=%d", type_parameter_index);
2903 } break;
2904
2905 case 0x10:
2906 // kind: type in extends clause of class or interface declaration
2907 // or in implements clause of interface declaration
2908 // location: ClassFile
2909
2910 {
2911 // struct:
2912 // supertype_target {
2913 // u2 supertype_index;
2914 // }
2915 //
2916 if ((byte_i_ref + 2) > type_annotations_typeArray->length()) {
2917 log_debug(redefine, class, annotation)("length() is too small for a supertype_target");
2918 return false;
2919 }
2920
2921 u2 supertype_index = Bytes::get_Java_u2((address)
2922 type_annotations_typeArray->adr_at(byte_i_ref));
2923 byte_i_ref += 2;
2924
2925 log_debug(redefine, class, annotation)("supertype_target: supertype_index=%d", supertype_index);
2926 } break;
2927
2928 case 0x11:
2929 // kind: type in bound of type parameter declaration of generic class or interface
2930 // location: ClassFile
2931 case 0x12:
2932 // kind: type in bound of type parameter declaration of generic method or constructor
2933 // location: method_info
2934
2935 {
2936 // struct:
2937 // type_parameter_bound_target {
2938 // u1 type_parameter_index;
2939 // u1 bound_index;
2940 // }
2941 //
2942 if ((byte_i_ref + 2) > type_annotations_typeArray->length()) {
2943 log_debug(redefine, class, annotation)("length() is too small for a type_parameter_bound_target");
2944 return false;
2945 }
2946
2947 u1 type_parameter_index = type_annotations_typeArray->at(byte_i_ref);
2948 byte_i_ref += 1;
2949 u1 bound_index = type_annotations_typeArray->at(byte_i_ref);
2950 byte_i_ref += 1;
2951
2952 log_debug(redefine, class, annotation)
2953 ("type_parameter_bound_target: type_parameter_index=%d, bound_index=%d", type_parameter_index, bound_index);
2954 } break;
2955
2956 case 0x13:
2957 // kind: type in field declaration
2958 // location: field_info
2959 case 0x14:
2960 // kind: return type of method, or type of newly constructed object
2961 // location: method_info
2962 case 0x15:
2963 // kind: receiver type of method or constructor
2964 // location: method_info
2965
2966 {
2967 // struct:
2968 // empty_target {
2969 // }
2970 //
2971 log_debug(redefine, class, annotation)("empty_target");
2972 } break;
2973
2974 case 0x16:
2975 // kind: type in formal parameter declaration of method, constructor, or lambda expression
2976 // location: method_info
2977
2978 {
2979 // struct:
2980 // formal_parameter_target {
2981 // u1 formal_parameter_index;
2982 // }
2983 //
2984 if ((byte_i_ref + 1) > type_annotations_typeArray->length()) {
2985 log_debug(redefine, class, annotation)("length() is too small for a formal_parameter_target");
2986 return false;
2987 }
2988
2989 u1 formal_parameter_index = type_annotations_typeArray->at(byte_i_ref);
2990 byte_i_ref += 1;
2991
2992 log_debug(redefine, class, annotation)
2993 ("formal_parameter_target: formal_parameter_index=%d", formal_parameter_index);
2994 } break;
2995
2996 case 0x17:
2997 // kind: type in throws clause of method or constructor
2998 // location: method_info
2999
3000 {
3001 // struct:
3002 // throws_target {
3003 // u2 throws_type_index
3004 // }
3005 //
3006 if ((byte_i_ref + 2) > type_annotations_typeArray->length()) {
3007 log_debug(redefine, class, annotation)("length() is too small for a throws_target");
3008 return false;
3009 }
3010
3011 u2 throws_type_index = Bytes::get_Java_u2((address)
3012 type_annotations_typeArray->adr_at(byte_i_ref));
3013 byte_i_ref += 2;
3014
3015 log_debug(redefine, class, annotation)("throws_target: throws_type_index=%d", throws_type_index);
3016 } break;
3017
3018 case 0x40:
3019 // kind: type in local variable declaration
3020 // location: Code
3021 case 0x41:
3022 // kind: type in resource variable declaration
3023 // location: Code
3024
3025 {
3026 // struct:
3027 // localvar_target {
3028 // u2 table_length;
3029 // struct {
3030 // u2 start_pc;
3031 // u2 length;
3032 // u2 index;
3033 // } table[table_length];
3034 // }
3035 //
3036 if ((byte_i_ref + 2) > type_annotations_typeArray->length()) {
3037 // not enough room for a table_length let alone the rest of a localvar_target
3038 log_debug(redefine, class, annotation)("length() is too small for a localvar_target table_length");
3039 return false;
3040 }
3041
3042 u2 table_length = Bytes::get_Java_u2((address)
3043 type_annotations_typeArray->adr_at(byte_i_ref));
3044 byte_i_ref += 2;
3045
3046 log_debug(redefine, class, annotation)("localvar_target: table_length=%d", table_length);
3047
3048 int table_struct_size = 2 + 2 + 2; // 3 u2 variables per table entry
3049 int table_size = table_length * table_struct_size;
3050
3051 if ((byte_i_ref + table_size) > type_annotations_typeArray->length()) {
3052 // not enough room for a table
3053 log_debug(redefine, class, annotation)("length() is too small for a table array of length %d", table_length);
3054 return false;
3055 }
3056
3057 // Skip over table
3058 byte_i_ref += table_size;
3059 } break;
3060
3061 case 0x42:
3062 // kind: type in exception parameter declaration
3063 // location: Code
3064
3065 {
3066 // struct:
3067 // catch_target {
3068 // u2 exception_table_index;
3069 // }
3070 //
3071 if ((byte_i_ref + 2) > type_annotations_typeArray->length()) {
3072 log_debug(redefine, class, annotation)("length() is too small for a catch_target");
3073 return false;
3074 }
3075
3076 u2 exception_table_index = Bytes::get_Java_u2((address)
3077 type_annotations_typeArray->adr_at(byte_i_ref));
3078 byte_i_ref += 2;
3079
3080 log_debug(redefine, class, annotation)("catch_target: exception_table_index=%d", exception_table_index);
3081 } break;
3082
3083 case 0x43:
3084 // kind: type in instanceof expression
3085 // location: Code
3086 case 0x44:
3087 // kind: type in new expression
3088 // location: Code
3089 case 0x45:
3090 // kind: type in method reference expression using ::new
3091 // location: Code
3092 case 0x46:
3093 // kind: type in method reference expression using ::Identifier
3094 // location: Code
3095
3096 {
3097 // struct:
3098 // offset_target {
3099 // u2 offset;
3100 // }
3101 //
3102 if ((byte_i_ref + 2) > type_annotations_typeArray->length()) {
3103 log_debug(redefine, class, annotation)("length() is too small for a offset_target");
3104 return false;
3105 }
3106
3107 u2 offset = Bytes::get_Java_u2((address)
3108 type_annotations_typeArray->adr_at(byte_i_ref));
3109 byte_i_ref += 2;
3110
3111 log_debug(redefine, class, annotation)("offset_target: offset=%d", offset);
3112 } break;
3113
3114 case 0x47:
3115 // kind: type in cast expression
3116 // location: Code
3117 case 0x48:
3118 // kind: type argument for generic constructor in new expression or
3119 // explicit constructor invocation statement
3120 // location: Code
3121 case 0x49:
3122 // kind: type argument for generic method in method invocation expression
3123 // location: Code
3124 case 0x4A:
3125 // kind: type argument for generic constructor in method reference expression using ::new
3126 // location: Code
3127 case 0x4B:
3128 // kind: type argument for generic method in method reference expression using ::Identifier
3129 // location: Code
3130
3131 {
3132 // struct:
3133 // type_argument_target {
3134 // u2 offset;
3135 // u1 type_argument_index;
3136 // }
3137 //
3138 if ((byte_i_ref + 3) > type_annotations_typeArray->length()) {
3139 log_debug(redefine, class, annotation)("length() is too small for a type_argument_target");
3140 return false;
3141 }
3142
3143 u2 offset = Bytes::get_Java_u2((address)
3144 type_annotations_typeArray->adr_at(byte_i_ref));
3145 byte_i_ref += 2;
3146 u1 type_argument_index = type_annotations_typeArray->at(byte_i_ref);
3147 byte_i_ref += 1;
3148
3149 log_debug(redefine, class, annotation)
3150 ("type_argument_target: offset=%d, type_argument_index=%d", offset, type_argument_index);
3151 } break;
3152
3153 default:
3154 log_debug(redefine, class, annotation)("unknown target_type");
3155 #ifdef ASSERT
3156 ShouldNotReachHere();
3157 #endif
3158 return false;
3159 }
3160
3161 return true;
3162 } // end skip_type_annotation_target()
3163
3164
3165 // Read, verify and skip over the type_path part so that rewriting
3166 // can continue in the later parts of the struct.
3167 //
3168 // type_path {
3169 // u1 path_length;
3170 // {
3171 // u1 type_path_kind;
3172 // u1 type_argument_index;
3173 // } path[path_length];
3174 // }
3175 //
3176 bool VM_RedefineClasses::skip_type_annotation_type_path(
3177 AnnotationArray* type_annotations_typeArray, int &byte_i_ref) {
3178
3179 if ((byte_i_ref + 1) > type_annotations_typeArray->length()) {
3180 // not enough room for a path_length let alone the rest of the type_path
3181 log_debug(redefine, class, annotation)("length() is too small for a type_path");
3182 return false;
3183 }
3184
3185 u1 path_length = type_annotations_typeArray->at(byte_i_ref);
3186 byte_i_ref += 1;
3187
3188 log_debug(redefine, class, annotation)("type_path: path_length=%d", path_length);
3189
3190 int calc_path_length = 0;
3191 for (; calc_path_length < path_length; calc_path_length++) {
3192 if ((byte_i_ref + 1 + 1) > type_annotations_typeArray->length()) {
3193 // not enough room for a path
3194 log_debug(redefine, class, annotation)
3195 ("length() is too small for path entry %d of %d", calc_path_length, path_length);
3196 return false;
3197 }
3198
3199 u1 type_path_kind = type_annotations_typeArray->at(byte_i_ref);
3200 byte_i_ref += 1;
3201 u1 type_argument_index = type_annotations_typeArray->at(byte_i_ref);
3202 byte_i_ref += 1;
3203
3204 log_debug(redefine, class, annotation)
3205 ("type_path: path[%d]: type_path_kind=%d, type_argument_index=%d",
3206 calc_path_length, type_path_kind, type_argument_index);
3207
3208 if (type_path_kind > 3 || (type_path_kind != 3 && type_argument_index != 0)) {
3209 // not enough room for a path
3210 log_debug(redefine, class, annotation)("inconsistent type_path values");
3211 return false;
3212 }
3213 }
3214 assert(path_length == calc_path_length, "sanity check");
3215
3216 return true;
3217 } // end skip_type_annotation_type_path()
3218
3219
3220 // Rewrite constant pool references in the method's stackmap table.
3221 // These "structures" are adapted from the StackMapTable_attribute that
3222 // is described in section 4.8.4 of the 6.0 version of the VM spec
3223 // (dated 2005.10.26):
3224 // file:///net/quincunx.sfbay/export/gbracha/ClassFile-Java6.pdf
3225 //
3226 // stack_map {
3227 // u2 number_of_entries;
3228 // stack_map_frame entries[number_of_entries];
3229 // }
3230 //
3231 void VM_RedefineClasses::rewrite_cp_refs_in_stack_map_table(
3232 const methodHandle& method) {
3233
3234 if (!method->has_stackmap_table()) {
3235 return;
3236 }
3237
3238 AnnotationArray* stackmap_data = method->stackmap_data();
3239 address stackmap_p = (address)stackmap_data->adr_at(0);
3240 address stackmap_end = stackmap_p + stackmap_data->length();
3241
3242 assert(stackmap_p + 2 <= stackmap_end, "no room for number_of_entries");
3243 u2 number_of_entries = Bytes::get_Java_u2(stackmap_p);
3244 stackmap_p += 2;
3245
3246 log_debug(redefine, class, stackmap)("number_of_entries=%u", number_of_entries);
3247
3248 // walk through each stack_map_frame
3249 u2 calc_number_of_entries = 0;
3250 for (; calc_number_of_entries < number_of_entries; calc_number_of_entries++) {
3251 // The stack_map_frame structure is a u1 frame_type followed by
3252 // 0 or more bytes of data:
3253 //
3254 // union stack_map_frame {
3255 // same_frame;
3256 // same_locals_1_stack_item_frame;
3257 // same_locals_1_stack_item_frame_extended;
3258 // chop_frame;
3259 // same_frame_extended;
3260 // append_frame;
3261 // full_frame;
3262 // }
3263
3264 assert(stackmap_p + 1 <= stackmap_end, "no room for frame_type");
3265 u1 frame_type = *stackmap_p;
3266 stackmap_p++;
3267
3268 // same_frame {
3269 // u1 frame_type = SAME; /* 0-63 */
3270 // }
3271 if (frame_type <= StackMapReader::SAME_FRAME_END) {
3272 // nothing more to do for same_frame
3273 }
3274
3275 // same_locals_1_stack_item_frame {
3276 // u1 frame_type = SAME_LOCALS_1_STACK_ITEM; /* 64-127 */
3277 // verification_type_info stack[1];
3278 // }
3279 else if (frame_type >= StackMapReader::SAME_LOCALS_1_STACK_ITEM_FRAME_START &&
3280 frame_type <= StackMapReader::SAME_LOCALS_1_STACK_ITEM_FRAME_END) {
3281 rewrite_cp_refs_in_verification_type_info(stackmap_p, stackmap_end,
3282 calc_number_of_entries, frame_type);
3283 }
3284
3285 // reserved for future use
3286 else if (frame_type >= StackMapReader::RESERVED_START &&
3287 frame_type <= StackMapReader::RESERVED_END) {
3288 // nothing more to do for reserved frame_types
3289 }
3290
3291 // same_locals_1_stack_item_frame_extended {
3292 // u1 frame_type = SAME_LOCALS_1_STACK_ITEM_EXTENDED; /* 247 */
3293 // u2 offset_delta;
3294 // verification_type_info stack[1];
3295 // }
3296 else if (frame_type == StackMapReader::SAME_LOCALS_1_STACK_ITEM_EXTENDED) {
3297 stackmap_p += 2;
3298 rewrite_cp_refs_in_verification_type_info(stackmap_p, stackmap_end,
3299 calc_number_of_entries, frame_type);
3300 }
3301
3302 // chop_frame {
3303 // u1 frame_type = CHOP; /* 248-250 */
3304 // u2 offset_delta;
3305 // }
3306 else if (frame_type >= StackMapReader::CHOP_FRAME_START &&
3307 frame_type <= StackMapReader::CHOP_FRAME_END) {
3308 stackmap_p += 2;
3309 }
3310
3311 // same_frame_extended {
3312 // u1 frame_type = SAME_EXTENDED; /* 251 */
3313 // u2 offset_delta;
3314 // }
3315 else if (frame_type == StackMapReader::SAME_FRAME_EXTENDED) {
3316 stackmap_p += 2;
3317 }
3318
3319 // append_frame {
3320 // u1 frame_type = APPEND; /* 252-254 */
3321 // u2 offset_delta;
3322 // verification_type_info locals[frame_type - SAME_EXTENDED];
3323 // }
3324 else if (frame_type >= StackMapReader::APPEND_FRAME_START &&
3325 frame_type <= StackMapReader::APPEND_FRAME_END) {
3326 assert(stackmap_p + 2 <= stackmap_end,
3327 "no room for offset_delta");
3328 stackmap_p += 2;
3329 u1 len = frame_type - StackMapReader::APPEND_FRAME_START + 1;
3330 for (u1 i = 0; i < len; i++) {
3331 rewrite_cp_refs_in_verification_type_info(stackmap_p, stackmap_end,
3332 calc_number_of_entries, frame_type);
3333 }
3334 }
3335
3336 // full_frame {
3337 // u1 frame_type = FULL_FRAME; /* 255 */
3338 // u2 offset_delta;
3339 // u2 number_of_locals;
3340 // verification_type_info locals[number_of_locals];
3341 // u2 number_of_stack_items;
3342 // verification_type_info stack[number_of_stack_items];
3343 // }
3344 else if (frame_type == StackMapReader::FULL_FRAME) {
3345 assert(stackmap_p + 2 + 2 <= stackmap_end,
3346 "no room for smallest full_frame");
3347 stackmap_p += 2;
3348
3349 u2 number_of_locals = Bytes::get_Java_u2(stackmap_p);
3350 stackmap_p += 2;
3351
3352 for (u2 locals_i = 0; locals_i < number_of_locals; locals_i++) {
3353 rewrite_cp_refs_in_verification_type_info(stackmap_p, stackmap_end,
3354 calc_number_of_entries, frame_type);
3355 }
3356
3357 // Use the largest size for the number_of_stack_items, but only get
3358 // the right number of bytes.
3359 u2 number_of_stack_items = Bytes::get_Java_u2(stackmap_p);
3360 stackmap_p += 2;
3361
3362 for (u2 stack_i = 0; stack_i < number_of_stack_items; stack_i++) {
3363 rewrite_cp_refs_in_verification_type_info(stackmap_p, stackmap_end,
3364 calc_number_of_entries, frame_type);
3365 }
3366 }
3367 } // end while there is a stack_map_frame
3368 assert(number_of_entries == calc_number_of_entries, "sanity check");
3369 } // end rewrite_cp_refs_in_stack_map_table()
3370
3371
3372 // Rewrite constant pool references in the verification type info
3373 // portion of the method's stackmap table. These "structures" are
3374 // adapted from the StackMapTable_attribute that is described in
3375 // section 4.8.4 of the 6.0 version of the VM spec (dated 2005.10.26):
3376 // file:///net/quincunx.sfbay/export/gbracha/ClassFile-Java6.pdf
3377 //
3378 // The verification_type_info structure is a u1 tag followed by 0 or
3379 // more bytes of data:
3380 //
3381 // union verification_type_info {
3382 // Top_variable_info;
3383 // Integer_variable_info;
3384 // Float_variable_info;
3385 // Long_variable_info;
3386 // Double_variable_info;
3387 // Null_variable_info;
3388 // UninitializedThis_variable_info;
3389 // Object_variable_info;
3390 // Uninitialized_variable_info;
3391 // }
3392 //
3393 void VM_RedefineClasses::rewrite_cp_refs_in_verification_type_info(
3394 address& stackmap_p_ref, address stackmap_end, u2 frame_i,
3395 u1 frame_type) {
3396
3397 assert(stackmap_p_ref + 1 <= stackmap_end, "no room for tag");
3398 u1 tag = *stackmap_p_ref;
3399 stackmap_p_ref++;
3400
3401 switch (tag) {
3402 // Top_variable_info {
3403 // u1 tag = ITEM_Top; /* 0 */
3404 // }
3405 // verificationType.hpp has zero as ITEM_Bogus instead of ITEM_Top
3406 case 0: // fall through
3407
3408 // Integer_variable_info {
3409 // u1 tag = ITEM_Integer; /* 1 */
3410 // }
3411 case ITEM_Integer: // fall through
3412
3413 // Float_variable_info {
3414 // u1 tag = ITEM_Float; /* 2 */
3415 // }
3416 case ITEM_Float: // fall through
3417
3418 // Double_variable_info {
3419 // u1 tag = ITEM_Double; /* 3 */
3420 // }
3421 case ITEM_Double: // fall through
3422
3423 // Long_variable_info {
3424 // u1 tag = ITEM_Long; /* 4 */
3425 // }
3426 case ITEM_Long: // fall through
3427
3428 // Null_variable_info {
3429 // u1 tag = ITEM_Null; /* 5 */
3430 // }
3431 case ITEM_Null: // fall through
3432
3433 // UninitializedThis_variable_info {
3434 // u1 tag = ITEM_UninitializedThis; /* 6 */
3435 // }
3436 case ITEM_UninitializedThis:
3437 // nothing more to do for the above tag types
3438 break;
3439
3440 // Object_variable_info {
3441 // u1 tag = ITEM_Object; /* 7 */
3442 // u2 cpool_index;
3443 // }
3444 case ITEM_Object:
3445 {
3446 assert(stackmap_p_ref + 2 <= stackmap_end, "no room for cpool_index");
3447 u2 cpool_index = Bytes::get_Java_u2(stackmap_p_ref);
3448 u2 new_cp_index = find_new_index(cpool_index);
3449 if (new_cp_index != 0) {
3450 log_debug(redefine, class, stackmap)("mapped old cpool_index=%d", cpool_index);
3451 Bytes::put_Java_u2(stackmap_p_ref, new_cp_index);
3452 cpool_index = new_cp_index;
3453 }
3454 stackmap_p_ref += 2;
3455
3456 log_debug(redefine, class, stackmap)
3457 ("frame_i=%u, frame_type=%u, cpool_index=%d", frame_i, frame_type, cpool_index);
3458 } break;
3459
3460 // Uninitialized_variable_info {
3461 // u1 tag = ITEM_Uninitialized; /* 8 */
3462 // u2 offset;
3463 // }
3464 case ITEM_Uninitialized:
3465 assert(stackmap_p_ref + 2 <= stackmap_end, "no room for offset");
3466 stackmap_p_ref += 2;
3467 break;
3468
3469 default:
3470 log_debug(redefine, class, stackmap)("frame_i=%u, frame_type=%u, bad tag=0x%x", frame_i, frame_type, tag);
3471 ShouldNotReachHere();
3472 break;
3473 } // end switch (tag)
3474 } // end rewrite_cp_refs_in_verification_type_info()
3475
3476
3477 // Change the constant pool associated with klass scratch_class to scratch_cp.
3478 // scratch_cp_length elements are copied from scratch_cp to a smaller constant pool
3479 // and the smaller constant pool is associated with scratch_class.
3480 void VM_RedefineClasses::set_new_constant_pool(
3481 ClassLoaderData* loader_data,
3482 InstanceKlass* scratch_class, constantPoolHandle scratch_cp,
3483 int scratch_cp_length, TRAPS) {
3484 assert(scratch_cp->length() >= scratch_cp_length, "sanity check");
3485
3486 // scratch_cp is a merged constant pool and has enough space for a
3487 // worst case merge situation. We want to associate the minimum
3488 // sized constant pool with the klass to save space.
3489 ConstantPool* cp = ConstantPool::allocate(loader_data, scratch_cp_length, CHECK);
3490 constantPoolHandle smaller_cp(THREAD, cp);
3491
3492 // preserve version() value in the smaller copy
3493 int version = scratch_cp->version();
3494 assert(version != 0, "sanity check");
3495 smaller_cp->set_version(version);
3496
3497 // attach klass to new constant pool
3498 // reference to the cp holder is needed for copy_operands()
3499 smaller_cp->set_pool_holder(scratch_class);
3500
3501 smaller_cp->copy_fields(scratch_cp());
3502
3503 scratch_cp->copy_cp_to(1, scratch_cp_length - 1, smaller_cp, 1, THREAD);
3504 if (HAS_PENDING_EXCEPTION) {
3505 // Exception is handled in the caller
3506 loader_data->add_to_deallocate_list(smaller_cp());
3507 return;
3508 }
3509 scratch_cp = smaller_cp;
3510
3511 // attach new constant pool to klass
3512 scratch_class->set_constants(scratch_cp());
3513 scratch_cp->initialize_unresolved_klasses(loader_data, CHECK);
3514
3515 int i; // for portability
3516
3517 // update each field in klass to use new constant pool indices as needed
3518 int java_fields;
3519 int injected_fields;
3520 bool update_required = false;
3521 GrowableArray<FieldInfo>* fields = FieldInfoStream::create_FieldInfoArray(scratch_class->fieldinfo_stream(), &java_fields, &injected_fields);
3522 for (int i = 0; i < java_fields; i++) {
3523 FieldInfo* fi = fields->adr_at(i);
3524 jshort cur_index = fi->name_index();
3525 jshort new_index = find_new_index(cur_index);
3526 if (new_index != 0) {
3527 log_trace(redefine, class, constantpool)("field-name_index change: %d to %d", cur_index, new_index);
3528 fi->set_name_index(new_index);
3529 update_required = true;
3530 }
3531 cur_index = fi->signature_index();
3532 new_index = find_new_index(cur_index);
3533 if (new_index != 0) {
3534 log_trace(redefine, class, constantpool)("field-signature_index change: %d to %d", cur_index, new_index);
3535 fi->set_signature_index(new_index);
3536 update_required = true;
3537 }
3538 cur_index = fi->initializer_index();
3539 new_index = find_new_index(cur_index);
3540 if (new_index != 0) {
3541 log_trace(redefine, class, constantpool)("field-initval_index change: %d to %d", cur_index, new_index);
3542 fi->set_initializer_index(new_index);
3543 update_required = true;
3544 }
3545 cur_index = fi->generic_signature_index();
3546 new_index = find_new_index(cur_index);
3547 if (new_index != 0) {
3548 log_trace(redefine, class, constantpool)("field-generic_signature change: %d to %d", cur_index, new_index);
3549 fi->set_generic_signature_index(new_index);
3550 update_required = true;
3551 }
3552 }
3553 if (update_required) {
3554 Array<u1>* old_stream = scratch_class->fieldinfo_stream();
3555 assert(fields->length() == (java_fields + injected_fields), "Must be");
3556 Array<u1>* new_fis = FieldInfoStream::create_FieldInfoStream(fields, java_fields, injected_fields, scratch_class->class_loader_data(), CHECK);
3557 scratch_class->set_fieldinfo_stream(new_fis);
3558 MetadataFactory::free_array<u1>(scratch_class->class_loader_data(), old_stream);
3559
3560 Array<u1>* old_table = scratch_class->fieldinfo_search_table();
3561 Array<u1>* search_table = FieldInfoStream::create_search_table(scratch_class->constants(), new_fis, scratch_class->class_loader_data(), CHECK);
3562 scratch_class->set_fieldinfo_search_table(search_table);
3563 MetadataFactory::free_array<u1>(scratch_class->class_loader_data(), old_table);
3564
3565 DEBUG_ONLY(FieldInfoStream::validate_search_table(scratch_class->constants(), new_fis, search_table));
3566 }
3567
3568 // Update constant pool indices in the inner classes info to use
3569 // new constant indices as needed. The inner classes info is a
3570 // quadruple:
3571 // (inner_class_info, outer_class_info, inner_name, inner_access_flags)
3572 InnerClassesIterator iter(scratch_class);
3573 for (; !iter.done(); iter.next()) {
3574 int cur_index = iter.inner_class_info_index();
3575 if (cur_index == 0) {
3576 continue; // JVM spec. allows null inner class refs so skip it
3577 }
3578 u2 new_index = find_new_index(cur_index);
3579 if (new_index != 0) {
3580 log_trace(redefine, class, constantpool)("inner_class_info change: %d to %d", cur_index, new_index);
3581 iter.set_inner_class_info_index(new_index);
3582 }
3583 cur_index = iter.outer_class_info_index();
3584 new_index = find_new_index(cur_index);
3585 if (new_index != 0) {
3586 log_trace(redefine, class, constantpool)("outer_class_info change: %d to %d", cur_index, new_index);
3587 iter.set_outer_class_info_index(new_index);
3588 }
3589 cur_index = iter.inner_name_index();
3590 new_index = find_new_index(cur_index);
3591 if (new_index != 0) {
3592 log_trace(redefine, class, constantpool)("inner_name change: %d to %d", cur_index, new_index);
3593 iter.set_inner_name_index(new_index);
3594 }
3595 } // end for each inner class
3596
3597 // Attach each method in klass to the new constant pool and update
3598 // to use new constant pool indices as needed:
3599 Array<Method*>* methods = scratch_class->methods();
3600 for (i = methods->length() - 1; i >= 0; i--) {
3601 methodHandle method(THREAD, methods->at(i));
3602 method->set_constants(scratch_cp());
3603
3604 u2 new_index = find_new_index(method->name_index());
3605 if (new_index != 0) {
3606 log_trace(redefine, class, constantpool)
3607 ("method-name_index change: %d to %d", method->name_index(), new_index);
3608 method->set_name_index(new_index);
3609 }
3610 new_index = find_new_index(method->signature_index());
3611 if (new_index != 0) {
3612 log_trace(redefine, class, constantpool)
3613 ("method-signature_index change: %d to %d", method->signature_index(), new_index);
3614 method->set_signature_index(new_index);
3615 }
3616 new_index = find_new_index(method->generic_signature_index());
3617 if (new_index != 0) {
3618 log_trace(redefine, class, constantpool)
3619 ("method-generic_signature_index change: %d to %d", method->generic_signature_index(), new_index);
3620 method->constMethod()->set_generic_signature_index(new_index);
3621 }
3622
3623 // Update constant pool indices in the method's checked exception
3624 // table to use new constant indices as needed.
3625 int cext_length = method->checked_exceptions_length();
3626 if (cext_length > 0) {
3627 CheckedExceptionElement * cext_table =
3628 method->checked_exceptions_start();
3629 for (int j = 0; j < cext_length; j++) {
3630 int cur_index = cext_table[j].class_cp_index;
3631 int new_index = find_new_index(cur_index);
3632 if (new_index != 0) {
3633 log_trace(redefine, class, constantpool)("cext-class_cp_index change: %d to %d", cur_index, new_index);
3634 cext_table[j].class_cp_index = (u2)new_index;
3635 }
3636 } // end for each checked exception table entry
3637 } // end if there are checked exception table entries
3638
3639 // Update each catch type index in the method's exception table
3640 // to use new constant pool indices as needed. The exception table
3641 // holds quadruple entries of the form:
3642 // (beg_bci, end_bci, handler_bci, klass_index)
3643
3644 ExceptionTable ex_table(method());
3645 int ext_length = ex_table.length();
3646
3647 for (int j = 0; j < ext_length; j ++) {
3648 int cur_index = ex_table.catch_type_index(j);
3649 u2 new_index = find_new_index(cur_index);
3650 if (new_index != 0) {
3651 log_trace(redefine, class, constantpool)("ext-klass_index change: %d to %d", cur_index, new_index);
3652 ex_table.set_catch_type_index(j, new_index);
3653 }
3654 } // end for each exception table entry
3655
3656 // Update constant pool indices in the method's local variable
3657 // table to use new constant indices as needed. The local variable
3658 // table hold sextuple entries of the form:
3659 // (start_pc, length, name_index, descriptor_index, signature_index, slot)
3660 int lvt_length = method->localvariable_table_length();
3661 if (lvt_length > 0) {
3662 LocalVariableTableElement * lv_table =
3663 method->localvariable_table_start();
3664 for (int j = 0; j < lvt_length; j++) {
3665 int cur_index = lv_table[j].name_cp_index;
3666 int new_index = find_new_index(cur_index);
3667 if (new_index != 0) {
3668 log_trace(redefine, class, constantpool)("lvt-name_cp_index change: %d to %d", cur_index, new_index);
3669 lv_table[j].name_cp_index = (u2)new_index;
3670 }
3671 cur_index = lv_table[j].descriptor_cp_index;
3672 new_index = find_new_index(cur_index);
3673 if (new_index != 0) {
3674 log_trace(redefine, class, constantpool)("lvt-descriptor_cp_index change: %d to %d", cur_index, new_index);
3675 lv_table[j].descriptor_cp_index = (u2)new_index;
3676 }
3677 cur_index = lv_table[j].signature_cp_index;
3678 new_index = find_new_index(cur_index);
3679 if (new_index != 0) {
3680 log_trace(redefine, class, constantpool)("lvt-signature_cp_index change: %d to %d", cur_index, new_index);
3681 lv_table[j].signature_cp_index = (u2)new_index;
3682 }
3683 } // end for each local variable table entry
3684 } // end if there are local variable table entries
3685
3686 // Update constant pool indices in the method's method_parameters.
3687 int mp_length = method->method_parameters_length();
3688 if (mp_length > 0) {
3689 MethodParametersElement* elem = method->method_parameters_start();
3690 for (int j = 0; j < mp_length; j++) {
3691 const int cp_index = elem[j].name_cp_index;
3692 const int new_cp_index = find_new_index(cp_index);
3693 if (new_cp_index != 0) {
3694 elem[j].name_cp_index = (u2)new_cp_index;
3695 }
3696 }
3697 }
3698
3699 rewrite_cp_refs_in_stack_map_table(method);
3700 } // end for each method
3701 } // end set_new_constant_pool()
3702
3703
3704 // Unevolving classes may point to methods of the_class directly
3705 // from their constant pool caches, itables, and/or vtables. We
3706 // use the ClassLoaderDataGraph::classes_do() facility and this helper
3707 // to fix up these pointers. MethodData also points to old methods and
3708 // must be cleaned.
3709
3710 // Adjust cpools and vtables closure
3711 void VM_RedefineClasses::AdjustAndCleanMetadata::do_klass(Klass* k) {
3712
3713 // This is a very busy routine. We don't want too much tracing
3714 // printed out.
3715 bool trace_name_printed = false;
3716
3717 // If the class being redefined is java.lang.Object, we need to fix all
3718 // array class vtables also. The _has_redefined_Object flag is global.
3719 // Once the java.lang.Object has been redefined (by the current or one
3720 // of the previous VM_RedefineClasses operations) we have to always
3721 // adjust method entries for array classes.
3722 if (k->is_array_klass() && _has_redefined_Object) {
3723 k->vtable().adjust_method_entries(&trace_name_printed);
3724
3725 } else if (k->is_instance_klass()) {
3726 HandleMark hm(_thread);
3727 InstanceKlass *ik = InstanceKlass::cast(k);
3728
3729 // Clean MethodData of this class's methods so they don't refer to
3730 // old methods that are no longer running.
3731 Array<Method*>* methods = ik->methods();
3732 int num_methods = methods->length();
3733 for (int index = 0; index < num_methods; ++index) {
3734 if (methods->at(index)->method_data() != nullptr) {
3735 methods->at(index)->method_data()->clean_weak_method_links();
3736 }
3737 }
3738
3739 // Adjust all vtables, default methods and itables, to clean out old methods.
3740 ResourceMark rm(_thread);
3741 if (ik->vtable_length() > 0) {
3742 ik->vtable().adjust_method_entries(&trace_name_printed);
3743 ik->adjust_default_methods(&trace_name_printed);
3744 }
3745
3746 if (ik->itable_length() > 0) {
3747 ik->itable().adjust_method_entries(&trace_name_printed);
3748 }
3749
3750 // The constant pools in other classes (other_cp) can refer to
3751 // old methods. We have to update method information in
3752 // other_cp's cache. If other_cp has a previous version, then we
3753 // have to repeat the process for each previous version. The
3754 // constant pool cache holds the Method*s for non-virtual
3755 // methods and for virtual, final methods.
3756 //
3757 // Special case: if the current class is being redefined by the current
3758 // VM_RedefineClasses operation, then new_cp has already been attached
3759 // to the_class and old_cp has already been added as a previous version.
3760 // The new_cp doesn't have any cached references to old methods so it
3761 // doesn't need to be updated and we could optimize by skipping it.
3762 // However, the current class can be marked as being redefined by another
3763 // VM_RedefineClasses operation which has already executed its doit_prologue
3764 // and needs cpcache method entries adjusted. For simplicity, the cpcache
3765 // update is done unconditionally. It should result in doing nothing for
3766 // classes being redefined by the current VM_RedefineClasses operation.
3767 // Method entries in the previous version(s) are adjusted as well.
3768 ConstantPoolCache* cp_cache;
3769
3770 // this klass' constant pool cache may need adjustment
3771 ConstantPool* other_cp = ik->constants();
3772 cp_cache = other_cp->cache();
3773 if (cp_cache != nullptr) {
3774 cp_cache->adjust_method_entries(&trace_name_printed);
3775 }
3776
3777 // the previous versions' constant pool caches may need adjustment
3778 for (InstanceKlass* pv_node = ik->previous_versions();
3779 pv_node != nullptr;
3780 pv_node = pv_node->previous_versions()) {
3781 cp_cache = pv_node->constants()->cache();
3782 if (cp_cache != nullptr) {
3783 cp_cache->adjust_method_entries(&trace_name_printed);
3784 }
3785 }
3786 }
3787 }
3788
3789 void VM_RedefineClasses::update_jmethod_ids() {
3790 for (int j = 0; j < _matching_methods_length; ++j) {
3791 Method* old_method = _matching_old_methods[j];
3792 // The method_idnum should be within the range of 1..number-of-methods
3793 // until incremented later for obsolete methods.
3794 // The increment is so if a jmethodID is created for an old obsolete method
3795 // it gets a new jmethodID cache slot in the InstanceKlass.
3796 // They're cleaned out later when all methods of the previous version are purged.
3797 assert(old_method->method_idnum() <= _old_methods->length(),
3798 "shouldn't be incremented yet for obsolete methods");
3799 jmethodID jmid = old_method->find_jmethod_id_or_null();
3800 if (jmid != nullptr) {
3801 // There is a jmethodID, change it to point to the new method
3802 Method* new_method = _matching_new_methods[j];
3803 Method::change_method_associated_with_jmethod_id(jmid, new_method);
3804 assert(Method::resolve_jmethod_id(jmid) == _matching_new_methods[j],
3805 "should be replaced");
3806 }
3807 }
3808 }
3809
3810 int VM_RedefineClasses::check_methods_and_mark_as_obsolete() {
3811 int emcp_method_count = 0;
3812 int obsolete_count = 0;
3813 int old_index = 0;
3814 for (int j = 0; j < _matching_methods_length; ++j, ++old_index) {
3815 Method* old_method = _matching_old_methods[j];
3816 Method* new_method = _matching_new_methods[j];
3817 Method* old_array_method;
3818
3819 // Maintain an old_index into the _old_methods array by skipping
3820 // deleted methods
3821 while ((old_array_method = _old_methods->at(old_index)) != old_method) {
3822 ++old_index;
3823 }
3824
3825 if (MethodComparator::methods_EMCP(old_method, new_method)) {
3826 // The EMCP definition from JSR-163 requires the bytecodes to be
3827 // the same with the exception of constant pool indices which may
3828 // differ. However, the constants referred to by those indices
3829 // must be the same.
3830 //
3831 // We use methods_EMCP() for comparison since constant pool
3832 // merging can remove duplicate constant pool entries that were
3833 // present in the old method and removed from the rewritten new
3834 // method. A faster binary comparison function would consider the
3835 // old and new methods to be different when they are actually
3836 // EMCP.
3837 //
3838 // The old and new methods are EMCP and you would think that we
3839 // could get rid of one of them here and now and save some space.
3840 // However, the concept of EMCP only considers the bytecodes and
3841 // the constant pool entries in the comparison. Other things,
3842 // e.g., the line number table (LNT) or the local variable table
3843 // (LVT) don't count in the comparison. So the new (and EMCP)
3844 // method can have a new LNT that we need so we can't just
3845 // overwrite the new method with the old method.
3846 //
3847 // When this routine is called, we have already attached the new
3848 // methods to the_class so the old methods are effectively
3849 // overwritten. However, if an old method is still executing,
3850 // then the old method cannot be collected until sometime after
3851 // the old method call has returned. So the overwriting of old
3852 // methods by new methods will save us space except for those
3853 // (hopefully few) old methods that are still executing.
3854 //
3855 // A method refers to a ConstMethod* and this presents another
3856 // possible avenue to space savings. The ConstMethod* in the
3857 // new method contains possibly new attributes (LNT, LVT, etc).
3858 // At first glance, it seems possible to save space by replacing
3859 // the ConstMethod* in the old method with the ConstMethod*
3860 // from the new method. The old and new methods would share the
3861 // same ConstMethod* and we would save the space occupied by
3862 // the old ConstMethod*. However, the ConstMethod* contains
3863 // a back reference to the containing method. Sharing the
3864 // ConstMethod* between two methods could lead to confusion in
3865 // the code that uses the back reference. This would lead to
3866 // brittle code that could be broken in non-obvious ways now or
3867 // in the future.
3868 //
3869 // Another possibility is to copy the ConstMethod* from the new
3870 // method to the old method and then overwrite the new method with
3871 // the old method. Since the ConstMethod* contains the bytecodes
3872 // for the method embedded in the oop, this option would change
3873 // the bytecodes out from under any threads executing the old
3874 // method and make the thread's bcp invalid. Since EMCP requires
3875 // that the bytecodes be the same modulo constant pool indices, it
3876 // is straight forward to compute the correct new bcp in the new
3877 // ConstMethod* from the old bcp in the old ConstMethod*. The
3878 // time consuming part would be searching all the frames in all
3879 // of the threads to find all of the calls to the old method.
3880 //
3881 // It looks like we will have to live with the limited savings
3882 // that we get from effectively overwriting the old methods
3883 // when the new methods are attached to the_class.
3884
3885 // Count number of methods that are EMCP. The method will be marked
3886 // old but not obsolete if it is EMCP.
3887 emcp_method_count++;
3888
3889 // An EMCP method is _not_ obsolete. An obsolete method has a
3890 // different jmethodID than the current method. An EMCP method
3891 // has the same jmethodID as the current method. Having the
3892 // same jmethodID for all EMCP versions of a method allows for
3893 // a consistent view of the EMCP methods regardless of which
3894 // EMCP method you happen to have in hand. For example, a
3895 // breakpoint set in one EMCP method will work for all EMCP
3896 // versions of the method including the current one.
3897 } else {
3898 // mark obsolete methods as such
3899 old_method->set_is_obsolete();
3900 obsolete_count++;
3901
3902 // obsolete methods need a unique idnum so they become new entries in
3903 // the jmethodID cache in InstanceKlass
3904 assert(old_method->method_idnum() == new_method->method_idnum(), "must match");
3905 u2 num = InstanceKlass::cast(_the_class)->next_method_idnum();
3906 if (num != ConstMethod::UNSET_IDNUM) {
3907 old_method->set_method_idnum(num);
3908 }
3909
3910 // With tracing we try not to "yack" too much. The position of
3911 // this trace assumes there are fewer obsolete methods than
3912 // EMCP methods.
3913 if (log_is_enabled(Trace, redefine, class, obsolete, mark)) {
3914 ResourceMark rm;
3915 log_trace(redefine, class, obsolete, mark)
3916 ("mark %s(%s) as obsolete", old_method->name()->as_C_string(), old_method->signature()->as_C_string());
3917 }
3918 }
3919 old_method->set_is_old();
3920 }
3921 for (int i = 0; i < _deleted_methods_length; ++i) {
3922 Method* old_method = _deleted_methods[i];
3923
3924 assert(!old_method->has_vtable_index(),
3925 "cannot delete methods with vtable entries");;
3926
3927 // Mark all deleted methods as old, obsolete and deleted
3928 old_method->set_is_deleted();
3929 old_method->set_is_old();
3930 old_method->set_is_obsolete();
3931 ++obsolete_count;
3932 // With tracing we try not to "yack" too much. The position of
3933 // this trace assumes there are fewer obsolete methods than
3934 // EMCP methods.
3935 if (log_is_enabled(Trace, redefine, class, obsolete, mark)) {
3936 ResourceMark rm;
3937 log_trace(redefine, class, obsolete, mark)
3938 ("mark deleted %s(%s) as obsolete", old_method->name()->as_C_string(), old_method->signature()->as_C_string());
3939 }
3940 }
3941 assert((emcp_method_count + obsolete_count) == _old_methods->length(),
3942 "sanity check");
3943 log_trace(redefine, class, obsolete, mark)("EMCP_cnt=%d, obsolete_cnt=%d", emcp_method_count, obsolete_count);
3944 return emcp_method_count;
3945 }
3946
3947 // This internal class transfers the native function registration from old methods
3948 // to new methods. It is designed to handle both the simple case of unchanged
3949 // native methods and the complex cases of native method prefixes being added and/or
3950 // removed.
3951 // It expects only to be used during the VM_RedefineClasses op (a safepoint).
3952 //
3953 // This class is used after the new methods have been installed in "the_class".
3954 //
3955 // So, for example, the following must be handled. Where 'm' is a method and
3956 // a number followed by an underscore is a prefix.
3957 //
3958 // Old Name New Name
3959 // Simple transfer to new method m -> m
3960 // Add prefix m -> 1_m
3961 // Remove prefix 1_m -> m
3962 // Simultaneous add of prefixes m -> 3_2_1_m
3963 // Simultaneous removal of prefixes 3_2_1_m -> m
3964 // Simultaneous add and remove 1_m -> 2_m
3965 // Same, caused by prefix removal only 3_2_1_m -> 3_2_m
3966 //
3967 class TransferNativeFunctionRegistration {
3968 private:
3969 InstanceKlass* the_class;
3970 int prefix_count;
3971 char** prefixes;
3972
3973 // Recursively search the binary tree of possibly prefixed method names.
3974 // Iteration could be used if all agents were well behaved. Full tree walk is
3975 // more resilent to agents not cleaning up intermediate methods.
3976 // Branch at each depth in the binary tree is:
3977 // (1) without the prefix.
3978 // (2) with the prefix.
3979 // where 'prefix' is the prefix at that 'depth' (first prefix, second prefix,...)
3980 Method* search_prefix_name_space(int depth, char* name_str, size_t name_len,
3981 Symbol* signature) {
3982 TempNewSymbol name_symbol = SymbolTable::probe(name_str, (int)name_len);
3983 if (name_symbol != nullptr) {
3984 Method* method = the_class->lookup_method(name_symbol, signature);
3985 if (method != nullptr) {
3986 // Even if prefixed, intermediate methods must exist.
3987 if (method->is_native()) {
3988 // Wahoo, we found a (possibly prefixed) version of the method, return it.
3989 return method;
3990 }
3991 if (depth < prefix_count) {
3992 // Try applying further prefixes (other than this one).
3993 method = search_prefix_name_space(depth+1, name_str, name_len, signature);
3994 if (method != nullptr) {
3995 return method; // found
3996 }
3997
3998 // Try adding this prefix to the method name and see if it matches
3999 // another method name.
4000 char* prefix = prefixes[depth];
4001 size_t prefix_len = strlen(prefix);
4002 size_t trial_len = name_len + prefix_len;
4003 char* trial_name_str = NEW_RESOURCE_ARRAY(char, trial_len + 1);
4004 strcpy(trial_name_str, prefix);
4005 strcat(trial_name_str, name_str);
4006 method = search_prefix_name_space(depth+1, trial_name_str, trial_len,
4007 signature);
4008 if (method != nullptr) {
4009 // If found along this branch, it was prefixed, mark as such
4010 method->set_is_prefixed_native();
4011 return method; // found
4012 }
4013 }
4014 }
4015 }
4016 return nullptr; // This whole branch bore nothing
4017 }
4018
4019 // Return the method name with old prefixes stripped away.
4020 char* method_name_without_prefixes(Method* method) {
4021 Symbol* name = method->name();
4022 char* name_str = name->as_utf8();
4023
4024 // Old prefixing may be defunct, strip prefixes, if any.
4025 for (int i = prefix_count-1; i >= 0; i--) {
4026 char* prefix = prefixes[i];
4027 size_t prefix_len = strlen(prefix);
4028 if (strncmp(prefix, name_str, prefix_len) == 0) {
4029 name_str += prefix_len;
4030 }
4031 }
4032 return name_str;
4033 }
4034
4035 // Strip any prefixes off the old native method, then try to find a
4036 // (possibly prefixed) new native that matches it.
4037 Method* strip_and_search_for_new_native(Method* method) {
4038 ResourceMark rm;
4039 char* name_str = method_name_without_prefixes(method);
4040 return search_prefix_name_space(0, name_str, strlen(name_str),
4041 method->signature());
4042 }
4043
4044 public:
4045
4046 // Construct a native method transfer processor for this class.
4047 TransferNativeFunctionRegistration(InstanceKlass* _the_class) {
4048 assert(SafepointSynchronize::is_at_safepoint(), "sanity check");
4049
4050 the_class = _the_class;
4051 prefixes = JvmtiExport::get_all_native_method_prefixes(&prefix_count);
4052 }
4053
4054 // Attempt to transfer any of the old or deleted methods that are native
4055 void transfer_registrations(Method** old_methods, int methods_length) {
4056 for (int j = 0; j < methods_length; j++) {
4057 Method* old_method = old_methods[j];
4058
4059 if (old_method->is_native() && old_method->has_native_function()) {
4060 Method* new_method = strip_and_search_for_new_native(old_method);
4061 if (new_method != nullptr) {
4062 // Actually set the native function in the new method.
4063 // Redefine does not send events (except CFLH), certainly not this
4064 // behind the scenes re-registration.
4065 new_method->set_native_function(old_method->native_function(),
4066 !Method::native_bind_event_is_interesting);
4067 }
4068 }
4069 }
4070 }
4071 };
4072
4073 // Don't lose the association between a native method and its JNI function.
4074 void VM_RedefineClasses::transfer_old_native_function_registrations(InstanceKlass* the_class) {
4075 TransferNativeFunctionRegistration transfer(the_class);
4076 transfer.transfer_registrations(_deleted_methods, _deleted_methods_length);
4077 transfer.transfer_registrations(_matching_old_methods, _matching_methods_length);
4078 }
4079
4080 // Deoptimize all compiled code that depends on the classes redefined.
4081 //
4082 // If the can_redefine_classes capability is obtained in the onload
4083 // phase or 'AlwaysRecordEvolDependencies' is true, then the compiler has
4084 // recorded all dependencies from startup. In that case we need only
4085 // deoptimize and throw away all compiled code that depends on the class.
4086 //
4087 // If can_redefine_classes is obtained sometime after the onload phase
4088 // (and 'AlwaysRecordEvolDependencies' is false) then the dependency
4089 // information may be incomplete. In that case the first call to
4090 // RedefineClasses causes all compiled code to be thrown away. As
4091 // can_redefine_classes has been obtained then all future compilations will
4092 // record dependencies so second and subsequent calls to RedefineClasses
4093 // need only throw away code that depends on the class.
4094 //
4095
4096 void VM_RedefineClasses::flush_dependent_code() {
4097 assert(SafepointSynchronize::is_at_safepoint(), "sanity check");
4098 assert(JvmtiExport::all_dependencies_are_recorded() || !AlwaysRecordEvolDependencies, "sanity check");
4099
4100 DeoptimizationScope deopt_scope;
4101
4102 // This is the first redefinition, mark all the nmethods for deoptimization
4103 if (!JvmtiExport::all_dependencies_are_recorded()) {
4104 CodeCache::mark_all_nmethods_for_evol_deoptimization(&deopt_scope);
4105 log_debug(redefine, class, nmethod)("Marked all nmethods for deopt");
4106 } else {
4107 CodeCache::mark_dependents_for_evol_deoptimization(&deopt_scope);
4108 log_debug(redefine, class, nmethod)("Marked dependent nmethods for deopt");
4109 }
4110
4111 deopt_scope.deoptimize_marked();
4112
4113 // From now on we know that the dependency information is complete
4114 JvmtiExport::set_all_dependencies_are_recorded(true);
4115 }
4116
4117 void VM_RedefineClasses::compute_added_deleted_matching_methods() {
4118 Method* old_method;
4119 Method* new_method;
4120
4121 _matching_old_methods = NEW_RESOURCE_ARRAY(Method*, _old_methods->length());
4122 _matching_new_methods = NEW_RESOURCE_ARRAY(Method*, _old_methods->length());
4123 _added_methods = NEW_RESOURCE_ARRAY(Method*, _new_methods->length());
4124 _deleted_methods = NEW_RESOURCE_ARRAY(Method*, _old_methods->length());
4125
4126 _matching_methods_length = 0;
4127 _deleted_methods_length = 0;
4128 _added_methods_length = 0;
4129
4130 int nj = 0;
4131 int oj = 0;
4132 while (true) {
4133 if (oj >= _old_methods->length()) {
4134 if (nj >= _new_methods->length()) {
4135 break; // we've looked at everything, done
4136 }
4137 // New method at the end
4138 new_method = _new_methods->at(nj);
4139 _added_methods[_added_methods_length++] = new_method;
4140 ++nj;
4141 } else if (nj >= _new_methods->length()) {
4142 // Old method, at the end, is deleted
4143 old_method = _old_methods->at(oj);
4144 _deleted_methods[_deleted_methods_length++] = old_method;
4145 ++oj;
4146 } else {
4147 old_method = _old_methods->at(oj);
4148 new_method = _new_methods->at(nj);
4149 if (old_method->name() == new_method->name()) {
4150 if (old_method->signature() == new_method->signature()) {
4151 _matching_old_methods[_matching_methods_length ] = old_method;
4152 _matching_new_methods[_matching_methods_length++] = new_method;
4153 ++nj;
4154 ++oj;
4155 } else {
4156 // added overloaded have already been moved to the end,
4157 // so this is a deleted overloaded method
4158 _deleted_methods[_deleted_methods_length++] = old_method;
4159 ++oj;
4160 }
4161 } else { // names don't match
4162 if (old_method->name()->fast_compare(new_method->name()) > 0) {
4163 // new method
4164 _added_methods[_added_methods_length++] = new_method;
4165 ++nj;
4166 } else {
4167 // deleted method
4168 _deleted_methods[_deleted_methods_length++] = old_method;
4169 ++oj;
4170 }
4171 }
4172 }
4173 }
4174 assert(_matching_methods_length + _deleted_methods_length == _old_methods->length(), "sanity");
4175 assert(_matching_methods_length + _added_methods_length == _new_methods->length(), "sanity");
4176 }
4177
4178
4179 void VM_RedefineClasses::swap_annotations(InstanceKlass* the_class,
4180 InstanceKlass* scratch_class) {
4181 // Swap annotation fields values
4182 Annotations* old_annotations = the_class->annotations();
4183 the_class->set_annotations(scratch_class->annotations());
4184 scratch_class->set_annotations(old_annotations);
4185 }
4186
4187
4188 // Install the redefinition of a class:
4189 // - house keeping (flushing breakpoints and caches, deoptimizing
4190 // dependent compiled code)
4191 // - replacing parts in the_class with parts from scratch_class
4192 // - adding a weak reference to track the obsolete but interesting
4193 // parts of the_class
4194 // - adjusting constant pool caches and vtables in other classes
4195 // that refer to methods in the_class. These adjustments use the
4196 // ClassLoaderDataGraph::classes_do() facility which only allows
4197 // a helper method to be specified. The interesting parameters
4198 // that we would like to pass to the helper method are saved in
4199 // static global fields in the VM operation.
4200 void VM_RedefineClasses::redefine_single_class(Thread* current, jclass the_jclass,
4201 InstanceKlass* scratch_class) {
4202
4203 HandleMark hm(current); // make sure handles from this call are freed
4204
4205 if (log_is_enabled(Info, redefine, class, timer)) {
4206 _timer_rsc_phase1.start();
4207 }
4208
4209 InstanceKlass* the_class = get_ik(the_jclass);
4210
4211 // Set a flag to control and optimize adjusting method entries
4212 _has_redefined_Object |= the_class == vmClasses::Object_klass();
4213
4214 // Remove all breakpoints in methods of this class
4215 JvmtiBreakpoints& jvmti_breakpoints = JvmtiCurrentBreakpoints::get_jvmti_breakpoints();
4216 jvmti_breakpoints.clearall_in_class_at_safepoint(the_class);
4217
4218 _old_methods = the_class->methods();
4219 _new_methods = scratch_class->methods();
4220 _the_class = the_class;
4221 compute_added_deleted_matching_methods();
4222 update_jmethod_ids();
4223
4224 _any_class_has_resolved_methods = the_class->has_resolved_methods() || _any_class_has_resolved_methods;
4225
4226 // Attach new constant pool to the original klass. The original
4227 // klass still refers to the old constant pool (for now).
4228 scratch_class->constants()->set_pool_holder(the_class);
4229
4230 #if 0
4231 // In theory, with constant pool merging in place we should be able
4232 // to save space by using the new, merged constant pool in place of
4233 // the old constant pool(s). By "pool(s)" I mean the constant pool in
4234 // the klass version we are replacing now and any constant pool(s) in
4235 // previous versions of klass. Nice theory, doesn't work in practice.
4236 // When this code is enabled, even simple programs throw NullPointer
4237 // exceptions. I'm guessing that this is caused by some constant pool
4238 // cache difference between the new, merged constant pool and the
4239 // constant pool that was just being used by the klass. I'm keeping
4240 // this code around to archive the idea, but the code has to remain
4241 // disabled for now.
4242
4243 // Attach each old method to the new constant pool. This can be
4244 // done here since we are past the bytecode verification and
4245 // constant pool optimization phases.
4246 for (int i = _old_methods->length() - 1; i >= 0; i--) {
4247 Method* method = _old_methods->at(i);
4248 method->set_constants(scratch_class->constants());
4249 }
4250
4251 // NOTE: this doesn't work because you can redefine the same class in two
4252 // threads, each getting their own constant pool data appended to the
4253 // original constant pool. In order for the new methods to work when they
4254 // become old methods, they need to keep their updated copy of the constant pool.
4255
4256 {
4257 // walk all previous versions of the klass
4258 InstanceKlass *ik = the_class;
4259 PreviousVersionWalker pvw(ik);
4260 do {
4261 ik = pvw.next_previous_version();
4262 if (ik != nullptr) {
4263
4264 // attach previous version of klass to the new constant pool
4265 ik->set_constants(scratch_class->constants());
4266
4267 // Attach each method in the previous version of klass to the
4268 // new constant pool
4269 Array<Method*>* prev_methods = ik->methods();
4270 for (int i = prev_methods->length() - 1; i >= 0; i--) {
4271 Method* method = prev_methods->at(i);
4272 method->set_constants(scratch_class->constants());
4273 }
4274 }
4275 } while (ik != nullptr);
4276 }
4277 #endif
4278
4279 // Replace methods and constantpool
4280 the_class->set_methods(_new_methods);
4281 scratch_class->set_methods(_old_methods); // To prevent potential GCing of the old methods,
4282 // and to be able to undo operation easily.
4283
4284 Array<int>* old_ordering = the_class->method_ordering();
4285 the_class->set_method_ordering(scratch_class->method_ordering());
4286 scratch_class->set_method_ordering(old_ordering);
4287
4288 ConstantPool* old_constants = the_class->constants();
4289 the_class->set_constants(scratch_class->constants());
4290 scratch_class->set_constants(old_constants); // See the previous comment.
4291 #if 0
4292 // We are swapping the guts of "the new class" with the guts of "the
4293 // class". Since the old constant pool has just been attached to "the
4294 // new class", it seems logical to set the pool holder in the old
4295 // constant pool also. However, doing this will change the observable
4296 // class hierarchy for any old methods that are still executing. A
4297 // method can query the identity of its "holder" and this query uses
4298 // the method's constant pool link to find the holder. The change in
4299 // holding class from "the class" to "the new class" can confuse
4300 // things.
4301 //
4302 // Setting the old constant pool's holder will also cause
4303 // verification done during vtable initialization below to fail.
4304 // During vtable initialization, the vtable's class is verified to be
4305 // a subtype of the method's holder. The vtable's class is "the
4306 // class" and the method's holder is gotten from the constant pool
4307 // link in the method itself. For "the class"'s directly implemented
4308 // methods, the method holder is "the class" itself (as gotten from
4309 // the new constant pool). The check works fine in this case. The
4310 // check also works fine for methods inherited from super classes.
4311 //
4312 // Miranda methods are a little more complicated. A miranda method is
4313 // provided by an interface when the class implementing the interface
4314 // does not provide its own method. These interfaces are implemented
4315 // internally as an InstanceKlass. These special instanceKlasses
4316 // share the constant pool of the class that "implements" the
4317 // interface. By sharing the constant pool, the method holder of a
4318 // miranda method is the class that "implements" the interface. In a
4319 // non-redefine situation, the subtype check works fine. However, if
4320 // the old constant pool's pool holder is modified, then the check
4321 // fails because there is no class hierarchy relationship between the
4322 // vtable's class and "the new class".
4323
4324 old_constants->set_pool_holder(scratch_class());
4325 #endif
4326
4327 // track number of methods that are EMCP for add_previous_version() call below
4328 int emcp_method_count = check_methods_and_mark_as_obsolete();
4329 transfer_old_native_function_registrations(the_class);
4330
4331 if (scratch_class->get_cached_class_file() != the_class->get_cached_class_file()) {
4332 // 1. the_class doesn't have a cache yet, scratch_class does have a cache.
4333 // 2. The same class can be present twice in the scratch classes list or there
4334 // are multiple concurrent RetransformClasses calls on different threads.
4335 // the_class and scratch_class have the same cached bytes, but different buffers.
4336 // In such cases we need to deallocate one of the buffers.
4337 // 3. RedefineClasses and the_class has cached bytes from a previous transformation.
4338 // In the case we need to use class bytes from scratch_class.
4339 if (the_class->get_cached_class_file() != nullptr) {
4340 os::free(the_class->get_cached_class_file());
4341 }
4342 the_class->set_cached_class_file(scratch_class->get_cached_class_file());
4343 }
4344
4345 // null out in scratch class to not delete twice. The class to be redefined
4346 // always owns these bytes.
4347 scratch_class->set_cached_class_file(nullptr);
4348
4349 // Replace inner_classes
4350 Array<u2>* old_inner_classes = the_class->inner_classes();
4351 the_class->set_inner_classes(scratch_class->inner_classes());
4352 scratch_class->set_inner_classes(old_inner_classes);
4353
4354 // Initialize the vtable and interface table after
4355 // methods have been rewritten
4356 // no exception should happen here since we explicitly
4357 // do not check loader constraints.
4358 // compare_and_normalize_class_versions has already checked:
4359 // - classloaders unchanged, signatures unchanged
4360 // - all instanceKlasses for redefined classes reused & contents updated
4361 the_class->vtable().initialize_vtable();
4362 the_class->itable().initialize_itable();
4363
4364 // Update jmethodID cache if present.
4365 the_class->update_methods_jmethod_cache();
4366
4367 // Copy the "source debug extension" attribute from new class version
4368 the_class->set_source_debug_extension(
4369 scratch_class->source_debug_extension(),
4370 scratch_class->source_debug_extension() == nullptr ? 0 :
4371 (int)strlen(scratch_class->source_debug_extension()));
4372
4373 // Use of javac -g could be different in the old and the new
4374 if (scratch_class->has_localvariable_table() !=
4375 the_class->has_localvariable_table()) {
4376 the_class->set_has_localvariable_table(scratch_class->has_localvariable_table());
4377 }
4378
4379 swap_annotations(the_class, scratch_class);
4380
4381 // Replace minor version number of class file
4382 u2 old_minor_version = the_class->constants()->minor_version();
4383 the_class->constants()->set_minor_version(scratch_class->constants()->minor_version());
4384 scratch_class->constants()->set_minor_version(old_minor_version);
4385
4386 // Replace major version number of class file
4387 u2 old_major_version = the_class->constants()->major_version();
4388 the_class->constants()->set_major_version(scratch_class->constants()->major_version());
4389 scratch_class->constants()->set_major_version(old_major_version);
4390
4391 // Replace CP indexes for class and name+type of enclosing method
4392 u2 old_class_idx = the_class->enclosing_method_class_index();
4393 u2 old_method_idx = the_class->enclosing_method_method_index();
4394 the_class->set_enclosing_method_indices(
4395 scratch_class->enclosing_method_class_index(),
4396 scratch_class->enclosing_method_method_index());
4397 scratch_class->set_enclosing_method_indices(old_class_idx, old_method_idx);
4398
4399 if (!the_class->has_been_redefined()) {
4400 the_class->set_has_been_redefined();
4401 }
4402
4403 // Scratch class is unloaded but still needs cleaning, and skipping for CDS.
4404 scratch_class->set_is_scratch_class();
4405
4406 // keep track of previous versions of this class
4407 the_class->add_previous_version(scratch_class, emcp_method_count);
4408
4409 JFR_ONLY(ON_KLASS_REDEFINITION(the_class, current);)
4410
4411 _timer_rsc_phase1.stop();
4412 if (log_is_enabled(Info, redefine, class, timer)) {
4413 _timer_rsc_phase2.start();
4414 }
4415
4416 if (the_class->oop_map_cache() != nullptr) {
4417 // Flush references to any obsolete methods from the oop map cache
4418 // so that obsolete methods are not pinned.
4419 the_class->oop_map_cache()->flush_obsolete_entries();
4420 }
4421
4422 increment_class_counter(the_class);
4423
4424 if (EventClassRedefinition::is_enabled()) {
4425 EventClassRedefinition event;
4426 event.set_classModificationCount(java_lang_Class::classRedefinedCount(the_class->java_mirror()));
4427 event.set_redefinedClass(the_class);
4428 event.set_redefinitionId(_id);
4429 event.commit();
4430 }
4431
4432 {
4433 ResourceMark rm(current);
4434 // increment the classRedefinedCount field in the_class and in any
4435 // direct and indirect subclasses of the_class
4436 log_info(redefine, class, load)
4437 ("redefined name=%s, count=%d (avail_mem=" UINT64_FORMAT "K)",
4438 the_class->external_name(), java_lang_Class::classRedefinedCount(the_class->java_mirror()), os::available_memory() >> 10);
4439 Events::log_redefinition(current, "redefined class name=%s, count=%d",
4440 the_class->external_name(),
4441 java_lang_Class::classRedefinedCount(the_class->java_mirror()));
4442
4443 }
4444 _timer_rsc_phase2.stop();
4445
4446 } // end redefine_single_class()
4447
4448
4449 // Increment the classRedefinedCount field in the specific InstanceKlass
4450 // and in all direct and indirect subclasses.
4451 void VM_RedefineClasses::increment_class_counter(InstanceKlass* ik) {
4452 for (ClassHierarchyIterator iter(ik); !iter.done(); iter.next()) {
4453 // Only update instanceKlasses
4454 Klass* sub = iter.klass();
4455 if (sub->is_instance_klass()) {
4456 oop class_mirror = InstanceKlass::cast(sub)->java_mirror();
4457 Klass* class_oop = java_lang_Class::as_Klass(class_mirror);
4458 int new_count = java_lang_Class::classRedefinedCount(class_mirror) + 1;
4459 java_lang_Class::set_classRedefinedCount(class_mirror, new_count);
4460
4461 if (class_oop != _the_class) {
4462 // _the_class count is printed at end of redefine_single_class()
4463 log_debug(redefine, class, subclass)("updated count in subclass=%s to %d", ik->external_name(), new_count);
4464 }
4465 }
4466 }
4467 }
4468
4469 void VM_RedefineClasses::CheckClass::do_klass(Klass* k) {
4470 bool no_old_methods = true; // be optimistic
4471
4472 // Both array and instance classes have vtables.
4473 // a vtable should never contain old or obsolete methods
4474 ResourceMark rm(_thread);
4475 if (k->vtable_length() > 0 &&
4476 !k->vtable().check_no_old_or_obsolete_entries()) {
4477 if (log_is_enabled(Trace, redefine, class, obsolete, metadata)) {
4478 log_trace(redefine, class, obsolete, metadata)
4479 ("klassVtable::check_no_old_or_obsolete_entries failure -- OLD or OBSOLETE method found -- class: %s",
4480 k->signature_name());
4481 k->vtable().dump_vtable();
4482 }
4483 no_old_methods = false;
4484 }
4485
4486 if (k->is_instance_klass()) {
4487 HandleMark hm(_thread);
4488 InstanceKlass *ik = InstanceKlass::cast(k);
4489
4490 // an itable should never contain old or obsolete methods
4491 if (ik->itable_length() > 0 &&
4492 !ik->itable().check_no_old_or_obsolete_entries()) {
4493 if (log_is_enabled(Trace, redefine, class, obsolete, metadata)) {
4494 log_trace(redefine, class, obsolete, metadata)
4495 ("klassItable::check_no_old_or_obsolete_entries failure -- OLD or OBSOLETE method found -- class: %s",
4496 ik->signature_name());
4497 ik->itable().dump_itable();
4498 }
4499 no_old_methods = false;
4500 }
4501
4502 // the constant pool cache should never contain non-deleted old or obsolete methods
4503 if (ik->constants() != nullptr &&
4504 ik->constants()->cache() != nullptr &&
4505 !ik->constants()->cache()->check_no_old_or_obsolete_entries()) {
4506 if (log_is_enabled(Trace, redefine, class, obsolete, metadata)) {
4507 log_trace(redefine, class, obsolete, metadata)
4508 ("cp-cache::check_no_old_or_obsolete_entries failure -- OLD or OBSOLETE method found -- class: %s",
4509 ik->signature_name());
4510 ik->constants()->cache()->dump_cache();
4511 }
4512 no_old_methods = false;
4513 }
4514 }
4515
4516 // print and fail guarantee if old methods are found.
4517 if (!no_old_methods) {
4518 if (log_is_enabled(Trace, redefine, class, obsolete, metadata)) {
4519 dump_methods();
4520 } else {
4521 log_trace(redefine, class)("Use the '-Xlog:redefine+class*:' option "
4522 "to see more info about the following guarantee() failure.");
4523 }
4524 guarantee(false, "OLD and/or OBSOLETE method(s) found");
4525 }
4526 }
4527
4528 u8 VM_RedefineClasses::next_id() {
4529 while (true) {
4530 u8 id = _id_counter;
4531 u8 next_id = id + 1;
4532 u8 result = Atomic::cmpxchg(&_id_counter, id, next_id);
4533 if (result == id) {
4534 return next_id;
4535 }
4536 }
4537 }
4538
4539 void VM_RedefineClasses::dump_methods() {
4540 int j;
4541 log_trace(redefine, class, dump)("_old_methods --");
4542 for (j = 0; j < _old_methods->length(); ++j) {
4543 LogStreamHandle(Trace, redefine, class, dump) log_stream;
4544 Method* m = _old_methods->at(j);
4545 log_stream.print("%4d (%5d) ", j, m->vtable_index());
4546 m->access_flags().print_on(&log_stream);
4547 log_stream.print(" -- ");
4548 m->print_name(&log_stream);
4549 log_stream.cr();
4550 }
4551 log_trace(redefine, class, dump)("_new_methods --");
4552 for (j = 0; j < _new_methods->length(); ++j) {
4553 LogStreamHandle(Trace, redefine, class, dump) log_stream;
4554 Method* m = _new_methods->at(j);
4555 log_stream.print("%4d (%5d) ", j, m->vtable_index());
4556 m->access_flags().print_on(&log_stream);
4557 log_stream.print(" -- ");
4558 m->print_name(&log_stream);
4559 log_stream.cr();
4560 }
4561 log_trace(redefine, class, dump)("_matching_methods --");
4562 for (j = 0; j < _matching_methods_length; ++j) {
4563 LogStreamHandle(Trace, redefine, class, dump) log_stream;
4564 Method* m = _matching_old_methods[j];
4565 log_stream.print("%4d (%5d) ", j, m->vtable_index());
4566 m->access_flags().print_on(&log_stream);
4567 log_stream.print(" -- ");
4568 m->print_name();
4569 log_stream.cr();
4570
4571 m = _matching_new_methods[j];
4572 log_stream.print(" (%5d) ", m->vtable_index());
4573 m->access_flags().print_on(&log_stream);
4574 log_stream.cr();
4575 }
4576 log_trace(redefine, class, dump)("_deleted_methods --");
4577 for (j = 0; j < _deleted_methods_length; ++j) {
4578 LogStreamHandle(Trace, redefine, class, dump) log_stream;
4579 Method* m = _deleted_methods[j];
4580 log_stream.print("%4d (%5d) ", j, m->vtable_index());
4581 m->access_flags().print_on(&log_stream);
4582 log_stream.print(" -- ");
4583 m->print_name(&log_stream);
4584 log_stream.cr();
4585 }
4586 log_trace(redefine, class, dump)("_added_methods --");
4587 for (j = 0; j < _added_methods_length; ++j) {
4588 LogStreamHandle(Trace, redefine, class, dump) log_stream;
4589 Method* m = _added_methods[j];
4590 log_stream.print("%4d (%5d) ", j, m->vtable_index());
4591 m->access_flags().print_on(&log_stream);
4592 log_stream.print(" -- ");
4593 m->print_name(&log_stream);
4594 log_stream.cr();
4595 }
4596 }
4597
4598 void VM_RedefineClasses::print_on_error(outputStream* st) const {
4599 VM_Operation::print_on_error(st);
4600 if (_the_class != nullptr) {
4601 ResourceMark rm;
4602 st->print_cr(", redefining class %s", _the_class->external_name());
4603 }
4604 }