1 /*
2 * Copyright (c) 2003, 2023, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
24
25 #include "precompiled.hpp"
26 #include "cds/metaspaceShared.hpp"
27 #include "classfile/classFileStream.hpp"
28 #include "classfile/classLoaderDataGraph.hpp"
29 #include "classfile/classLoadInfo.hpp"
30 #include "classfile/javaClasses.inline.hpp"
31 #include "classfile/metadataOnStackMark.hpp"
32 #include "classfile/symbolTable.hpp"
33 #include "classfile/klassFactory.hpp"
34 #include "classfile/verifier.hpp"
35 #include "classfile/vmClasses.hpp"
36 #include "classfile/vmSymbols.hpp"
37 #include "code/codeCache.hpp"
38 #include "compiler/compileBroker.hpp"
39 #include "interpreter/oopMapCache.hpp"
40 #include "interpreter/rewriter.hpp"
41 #include "jfr/jfrEvents.hpp"
42 #include "logging/logStream.hpp"
43 #include "memory/metadataFactory.hpp"
44 #include "memory/resourceArea.hpp"
45 #include "memory/universe.hpp"
46 #include "oops/annotations.hpp"
47 #include "oops/constantPool.hpp"
48 #include "oops/fieldStreams.inline.hpp"
49 #include "oops/klass.inline.hpp"
50 #include "oops/klassVtable.hpp"
51 #include "oops/oop.inline.hpp"
52 #include "oops/recordComponent.hpp"
53 #include "prims/jvmtiImpl.hpp"
54 #include "prims/jvmtiRedefineClasses.hpp"
55 #include "prims/jvmtiThreadState.inline.hpp"
56 #include "prims/resolvedMethodTable.hpp"
57 #include "prims/methodComparator.hpp"
58 #include "runtime/atomic.hpp"
59 #include "runtime/deoptimization.hpp"
60 #include "runtime/handles.inline.hpp"
61 #include "runtime/jniHandles.inline.hpp"
62 #include "runtime/relocator.hpp"
63 #include "runtime/safepointVerifiers.hpp"
64 #include "utilities/bitMap.inline.hpp"
65 #include "utilities/events.hpp"
66
67 Array<Method*>* VM_RedefineClasses::_old_methods = nullptr;
68 Array<Method*>* VM_RedefineClasses::_new_methods = nullptr;
69 Method** VM_RedefineClasses::_matching_old_methods = nullptr;
70 Method** VM_RedefineClasses::_matching_new_methods = nullptr;
71 Method** VM_RedefineClasses::_deleted_methods = nullptr;
72 Method** VM_RedefineClasses::_added_methods = nullptr;
73 int VM_RedefineClasses::_matching_methods_length = 0;
74 int VM_RedefineClasses::_deleted_methods_length = 0;
75 int VM_RedefineClasses::_added_methods_length = 0;
76
77 // This flag is global as the constructor does not reset it:
78 bool VM_RedefineClasses::_has_redefined_Object = false;
79 u8 VM_RedefineClasses::_id_counter = 0;
80
81 VM_RedefineClasses::VM_RedefineClasses(jint class_count,
82 const jvmtiClassDefinition *class_defs,
83 JvmtiClassLoadKind class_load_kind) {
84 _class_count = class_count;
85 _class_defs = class_defs;
86 _class_load_kind = class_load_kind;
87 _any_class_has_resolved_methods = false;
88 _res = JVMTI_ERROR_NONE;
89 _the_class = nullptr;
90 _id = next_id();
91 }
92
93 static inline InstanceKlass* get_ik(jclass def) {
94 oop mirror = JNIHandles::resolve_non_null(def);
95 return InstanceKlass::cast(java_lang_Class::as_Klass(mirror));
96 }
97
98 // If any of the classes are being redefined, wait
99 // Parallel constant pool merging leads to indeterminate constant pools.
100 void VM_RedefineClasses::lock_classes() {
101 JvmtiThreadState *state = JvmtiThreadState::state_for(JavaThread::current());
102 GrowableArray<Klass*>* redef_classes = state->get_classes_being_redefined();
103
104 MonitorLocker ml(RedefineClasses_lock);
105
106 if (redef_classes == nullptr) {
107 redef_classes = new (mtClass) GrowableArray<Klass*>(1, mtClass);
108 state->set_classes_being_redefined(redef_classes);
109 }
110
111 bool has_redefined;
112 do {
113 has_redefined = false;
114 // Go through classes each time until none are being redefined. Skip
115 // the ones that are being redefined by this thread currently. Class file
116 // load hook event may trigger new class redefine when we are redefining
117 // a class (after lock_classes()).
118 for (int i = 0; i < _class_count; i++) {
119 InstanceKlass* ik = get_ik(_class_defs[i].klass);
120 // Check if we are currently redefining the class in this thread already.
121 if (redef_classes->contains(ik)) {
122 assert(ik->is_being_redefined(), "sanity");
123 } else {
124 if (ik->is_being_redefined()) {
125 ml.wait();
126 has_redefined = true;
127 break; // for loop
128 }
129 }
130 }
131 } while (has_redefined);
132
133 for (int i = 0; i < _class_count; i++) {
134 InstanceKlass* ik = get_ik(_class_defs[i].klass);
135 redef_classes->push(ik); // Add to the _classes_being_redefined list
136 ik->set_is_being_redefined(true);
137 }
138 ml.notify_all();
139 }
140
141 void VM_RedefineClasses::unlock_classes() {
142 JvmtiThreadState *state = JvmtiThreadState::state_for(JavaThread::current());
143 GrowableArray<Klass*>* redef_classes = state->get_classes_being_redefined();
144 assert(redef_classes != nullptr, "_classes_being_redefined is not allocated");
145
146 MonitorLocker ml(RedefineClasses_lock);
147
148 for (int i = _class_count - 1; i >= 0; i--) {
149 InstanceKlass* def_ik = get_ik(_class_defs[i].klass);
150 if (redef_classes->length() > 0) {
151 // Remove the class from _classes_being_redefined list
152 Klass* k = redef_classes->pop();
153 assert(def_ik == k, "unlocking wrong class");
154 }
155 assert(def_ik->is_being_redefined(),
156 "should be being redefined to get here");
157
158 // Unlock after we finish all redefines for this class within
159 // the thread. Same class can be pushed to the list multiple
160 // times (not more than once by each recursive redefinition).
161 if (!redef_classes->contains(def_ik)) {
162 def_ik->set_is_being_redefined(false);
163 }
164 }
165 ml.notify_all();
166 }
167
168 bool VM_RedefineClasses::doit_prologue() {
169 if (_class_count == 0) {
170 _res = JVMTI_ERROR_NONE;
171 return false;
172 }
173 if (_class_defs == nullptr) {
174 _res = JVMTI_ERROR_NULL_POINTER;
175 return false;
176 }
177
178 for (int i = 0; i < _class_count; i++) {
179 if (_class_defs[i].klass == nullptr) {
180 _res = JVMTI_ERROR_INVALID_CLASS;
181 return false;
182 }
183 if (_class_defs[i].class_byte_count == 0) {
184 _res = JVMTI_ERROR_INVALID_CLASS_FORMAT;
185 return false;
186 }
187 if (_class_defs[i].class_bytes == nullptr) {
188 _res = JVMTI_ERROR_NULL_POINTER;
189 return false;
190 }
191
192 oop mirror = JNIHandles::resolve_non_null(_class_defs[i].klass);
193 // classes for primitives, arrays, and hidden classes
194 // cannot be redefined.
195 if (!is_modifiable_class(mirror)) {
196 _res = JVMTI_ERROR_UNMODIFIABLE_CLASS;
197 return false;
198 }
199 }
200
201 // Start timer after all the sanity checks; not quite accurate, but
202 // better than adding a bunch of stop() calls.
203 if (log_is_enabled(Info, redefine, class, timer)) {
204 _timer_vm_op_prologue.start();
205 }
206
207 lock_classes();
208 // We first load new class versions in the prologue, because somewhere down the
209 // call chain it is required that the current thread is a Java thread.
210 _res = load_new_class_versions();
211 if (_res != JVMTI_ERROR_NONE) {
212 // free any successfully created classes, since none are redefined
213 for (int i = 0; i < _class_count; i++) {
214 if (_scratch_classes[i] != nullptr) {
215 ClassLoaderData* cld = _scratch_classes[i]->class_loader_data();
216 // Free the memory for this class at class unloading time. Not before
217 // because CMS might think this is still live.
218 InstanceKlass* ik = get_ik(_class_defs[i].klass);
219 if (ik->get_cached_class_file() == _scratch_classes[i]->get_cached_class_file()) {
220 // Don't double-free cached_class_file copied from the original class if error.
221 _scratch_classes[i]->set_cached_class_file(nullptr);
222 }
223 cld->add_to_deallocate_list(InstanceKlass::cast(_scratch_classes[i]));
224 }
225 }
226 // Free os::malloc allocated memory in load_new_class_version.
227 os::free(_scratch_classes);
228 _timer_vm_op_prologue.stop();
229 unlock_classes();
230 return false;
231 }
232
233 _timer_vm_op_prologue.stop();
234 return true;
235 }
236
237 void VM_RedefineClasses::doit() {
238 Thread* current = Thread::current();
239
240 if (log_is_enabled(Info, redefine, class, timer)) {
241 _timer_vm_op_doit.start();
242 }
243
244 #if INCLUDE_CDS
245 if (UseSharedSpaces) {
246 // Sharing is enabled so we remap the shared readonly space to
247 // shared readwrite, private just in case we need to redefine
248 // a shared class. We do the remap during the doit() phase of
249 // the safepoint to be safer.
250 if (!MetaspaceShared::remap_shared_readonly_as_readwrite()) {
251 log_info(redefine, class, load)("failed to remap shared readonly space to readwrite, private");
252 _res = JVMTI_ERROR_INTERNAL;
253 _timer_vm_op_doit.stop();
254 return;
255 }
256 }
257 #endif
258
259 // Mark methods seen on stack and everywhere else so old methods are not
260 // cleaned up if they're on the stack.
261 MetadataOnStackMark md_on_stack(/*walk_all_metadata*/true, /*redefinition_walk*/true);
262 HandleMark hm(current); // make sure any handles created are deleted
263 // before the stack walk again.
264
265 for (int i = 0; i < _class_count; i++) {
266 redefine_single_class(current, _class_defs[i].klass, _scratch_classes[i]);
267 }
268
269 // Flush all compiled code that depends on the classes redefined.
270 flush_dependent_code();
271
272 // Adjust constantpool caches and vtables for all classes
273 // that reference methods of the evolved classes.
274 // Have to do this after all classes are redefined and all methods that
275 // are redefined are marked as old.
276 AdjustAndCleanMetadata adjust_and_clean_metadata(current);
277 ClassLoaderDataGraph::classes_do(&adjust_and_clean_metadata);
278
279 // JSR-292 support
280 if (_any_class_has_resolved_methods) {
281 bool trace_name_printed = false;
282 ResolvedMethodTable::adjust_method_entries(&trace_name_printed);
283 }
284
285 // Increment flag indicating that some invariants are no longer true.
286 // See jvmtiExport.hpp for detailed explanation.
287 JvmtiExport::increment_redefinition_count();
288
289 // check_class() is optionally called for product bits, but is
290 // always called for non-product bits.
291 #ifdef PRODUCT
292 if (log_is_enabled(Trace, redefine, class, obsolete, metadata)) {
293 #endif
294 log_trace(redefine, class, obsolete, metadata)("calling check_class");
295 CheckClass check_class(current);
296 ClassLoaderDataGraph::classes_do(&check_class);
297 #ifdef PRODUCT
298 }
299 #endif
300
301 // Clean up any metadata now unreferenced while MetadataOnStackMark is set.
302 ClassLoaderDataGraph::clean_deallocate_lists(false);
303
304 _timer_vm_op_doit.stop();
305 }
306
307 void VM_RedefineClasses::doit_epilogue() {
308 unlock_classes();
309
310 // Free os::malloc allocated memory.
311 os::free(_scratch_classes);
312
313 // Reset the_class to null for error printing.
314 _the_class = nullptr;
315
316 if (log_is_enabled(Info, redefine, class, timer)) {
317 // Used to have separate timers for "doit" and "all", but the timer
318 // overhead skewed the measurements.
319 julong doit_time = _timer_vm_op_doit.milliseconds();
320 julong all_time = _timer_vm_op_prologue.milliseconds() + doit_time;
321
322 log_info(redefine, class, timer)
323 ("vm_op: all=" JULONG_FORMAT " prologue=" JULONG_FORMAT " doit=" JULONG_FORMAT,
324 all_time, (julong)_timer_vm_op_prologue.milliseconds(), doit_time);
325 log_info(redefine, class, timer)
326 ("redefine_single_class: phase1=" JULONG_FORMAT " phase2=" JULONG_FORMAT,
327 (julong)_timer_rsc_phase1.milliseconds(), (julong)_timer_rsc_phase2.milliseconds());
328 }
329 }
330
331 bool VM_RedefineClasses::is_modifiable_class(oop klass_mirror) {
332 // classes for primitives cannot be redefined
333 if (java_lang_Class::is_primitive(klass_mirror)) {
334 return false;
335 }
336 Klass* k = java_lang_Class::as_Klass(klass_mirror);
337 // classes for arrays cannot be redefined
338 if (k == nullptr || !k->is_instance_klass()) {
339 return false;
340 }
341
342 // Cannot redefine or retransform a hidden class.
343 if (InstanceKlass::cast(k)->is_hidden()) {
344 return false;
345 }
346 if (InstanceKlass::cast(k) == vmClasses::Continuation_klass()) {
347 // Don't redefine Continuation class. See 8302779.
348 return false;
349 }
350 return true;
351 }
352
353 // Append the current entry at scratch_i in scratch_cp to *merge_cp_p
354 // where the end of *merge_cp_p is specified by *merge_cp_length_p. For
355 // direct CP entries, there is just the current entry to append. For
356 // indirect and double-indirect CP entries, there are zero or more
357 // referenced CP entries along with the current entry to append.
358 // Indirect and double-indirect CP entries are handled by recursive
359 // calls to append_entry() as needed. The referenced CP entries are
360 // always appended to *merge_cp_p before the referee CP entry. These
361 // referenced CP entries may already exist in *merge_cp_p in which case
362 // there is nothing extra to append and only the current entry is
363 // appended.
364 void VM_RedefineClasses::append_entry(const constantPoolHandle& scratch_cp,
365 int scratch_i, constantPoolHandle *merge_cp_p, int *merge_cp_length_p) {
366
367 // append is different depending on entry tag type
368 switch (scratch_cp->tag_at(scratch_i).value()) {
369
370 // The old verifier is implemented outside the VM. It loads classes,
371 // but does not resolve constant pool entries directly so we never
372 // see Class entries here with the old verifier. Similarly the old
373 // verifier does not like Class entries in the input constant pool.
374 // The split-verifier is implemented in the VM so it can optionally
375 // and directly resolve constant pool entries to load classes. The
376 // split-verifier can accept either Class entries or UnresolvedClass
377 // entries in the input constant pool. We revert the appended copy
378 // back to UnresolvedClass so that either verifier will be happy
379 // with the constant pool entry.
380 //
381 // this is an indirect CP entry so it needs special handling
382 case JVM_CONSTANT_Class:
383 case JVM_CONSTANT_UnresolvedClass:
384 {
385 int name_i = scratch_cp->klass_name_index_at(scratch_i);
386 int new_name_i = find_or_append_indirect_entry(scratch_cp, name_i, merge_cp_p,
387 merge_cp_length_p);
388
389 if (new_name_i != name_i) {
390 log_trace(redefine, class, constantpool)
391 ("Class entry@%d name_index change: %d to %d",
392 *merge_cp_length_p, name_i, new_name_i);
393 }
394
395 (*merge_cp_p)->temp_unresolved_klass_at_put(*merge_cp_length_p, new_name_i);
396 if (scratch_i != *merge_cp_length_p) {
397 // The new entry in *merge_cp_p is at a different index than
398 // the new entry in scratch_cp so we need to map the index values.
399 map_index(scratch_cp, scratch_i, *merge_cp_length_p);
400 }
401 (*merge_cp_length_p)++;
402 } break;
403
404 // these are direct CP entries so they can be directly appended,
405 // but double and long take two constant pool entries
406 case JVM_CONSTANT_Double: // fall through
407 case JVM_CONSTANT_Long:
408 {
409 ConstantPool::copy_entry_to(scratch_cp, scratch_i, *merge_cp_p, *merge_cp_length_p);
410
411 if (scratch_i != *merge_cp_length_p) {
412 // The new entry in *merge_cp_p is at a different index than
413 // the new entry in scratch_cp so we need to map the index values.
414 map_index(scratch_cp, scratch_i, *merge_cp_length_p);
415 }
416 (*merge_cp_length_p) += 2;
417 } break;
418
419 // these are direct CP entries so they can be directly appended
420 case JVM_CONSTANT_Float: // fall through
421 case JVM_CONSTANT_Integer: // fall through
422 case JVM_CONSTANT_Utf8: // fall through
423
424 // This was an indirect CP entry, but it has been changed into
425 // Symbol*s so this entry can be directly appended.
426 case JVM_CONSTANT_String: // fall through
427 {
428 ConstantPool::copy_entry_to(scratch_cp, scratch_i, *merge_cp_p, *merge_cp_length_p);
429
430 if (scratch_i != *merge_cp_length_p) {
431 // The new entry in *merge_cp_p is at a different index than
432 // the new entry in scratch_cp so we need to map the index values.
433 map_index(scratch_cp, scratch_i, *merge_cp_length_p);
434 }
435 (*merge_cp_length_p)++;
436 } break;
437
438 // this is an indirect CP entry so it needs special handling
439 case JVM_CONSTANT_NameAndType:
440 {
441 int name_ref_i = scratch_cp->name_ref_index_at(scratch_i);
442 int new_name_ref_i = find_or_append_indirect_entry(scratch_cp, name_ref_i, merge_cp_p,
443 merge_cp_length_p);
444
445 int signature_ref_i = scratch_cp->signature_ref_index_at(scratch_i);
446 int new_signature_ref_i = find_or_append_indirect_entry(scratch_cp, signature_ref_i,
447 merge_cp_p, merge_cp_length_p);
448
449 // If the referenced entries already exist in *merge_cp_p, then
450 // both new_name_ref_i and new_signature_ref_i will both be 0.
451 // In that case, all we are appending is the current entry.
452 if (new_name_ref_i != name_ref_i) {
453 log_trace(redefine, class, constantpool)
454 ("NameAndType entry@%d name_ref_index change: %d to %d",
455 *merge_cp_length_p, name_ref_i, new_name_ref_i);
456 }
457 if (new_signature_ref_i != signature_ref_i) {
458 log_trace(redefine, class, constantpool)
459 ("NameAndType entry@%d signature_ref_index change: %d to %d",
460 *merge_cp_length_p, signature_ref_i, new_signature_ref_i);
461 }
462
463 (*merge_cp_p)->name_and_type_at_put(*merge_cp_length_p,
464 new_name_ref_i, new_signature_ref_i);
465 if (scratch_i != *merge_cp_length_p) {
466 // The new entry in *merge_cp_p is at a different index than
467 // the new entry in scratch_cp so we need to map the index values.
468 map_index(scratch_cp, scratch_i, *merge_cp_length_p);
469 }
470 (*merge_cp_length_p)++;
471 } break;
472
473 // this is a double-indirect CP entry so it needs special handling
474 case JVM_CONSTANT_Fieldref: // fall through
475 case JVM_CONSTANT_InterfaceMethodref: // fall through
476 case JVM_CONSTANT_Methodref:
477 {
478 int klass_ref_i = scratch_cp->uncached_klass_ref_index_at(scratch_i);
479 int new_klass_ref_i = find_or_append_indirect_entry(scratch_cp, klass_ref_i,
480 merge_cp_p, merge_cp_length_p);
481
482 int name_and_type_ref_i = scratch_cp->uncached_name_and_type_ref_index_at(scratch_i);
483 int new_name_and_type_ref_i = find_or_append_indirect_entry(scratch_cp, name_and_type_ref_i,
484 merge_cp_p, merge_cp_length_p);
485
486 const char *entry_name = nullptr;
487 switch (scratch_cp->tag_at(scratch_i).value()) {
488 case JVM_CONSTANT_Fieldref:
489 entry_name = "Fieldref";
490 (*merge_cp_p)->field_at_put(*merge_cp_length_p, new_klass_ref_i,
491 new_name_and_type_ref_i);
492 break;
493 case JVM_CONSTANT_InterfaceMethodref:
494 entry_name = "IFMethodref";
495 (*merge_cp_p)->interface_method_at_put(*merge_cp_length_p,
496 new_klass_ref_i, new_name_and_type_ref_i);
497 break;
498 case JVM_CONSTANT_Methodref:
499 entry_name = "Methodref";
500 (*merge_cp_p)->method_at_put(*merge_cp_length_p, new_klass_ref_i,
501 new_name_and_type_ref_i);
502 break;
503 default:
504 guarantee(false, "bad switch");
505 break;
506 }
507
508 if (klass_ref_i != new_klass_ref_i) {
509 log_trace(redefine, class, constantpool)
510 ("%s entry@%d class_index changed: %d to %d", entry_name, *merge_cp_length_p, klass_ref_i, new_klass_ref_i);
511 }
512 if (name_and_type_ref_i != new_name_and_type_ref_i) {
513 log_trace(redefine, class, constantpool)
514 ("%s entry@%d name_and_type_index changed: %d to %d",
515 entry_name, *merge_cp_length_p, name_and_type_ref_i, new_name_and_type_ref_i);
516 }
517
518 if (scratch_i != *merge_cp_length_p) {
519 // The new entry in *merge_cp_p is at a different index than
520 // the new entry in scratch_cp so we need to map the index values.
521 map_index(scratch_cp, scratch_i, *merge_cp_length_p);
522 }
523 (*merge_cp_length_p)++;
524 } break;
525
526 // this is an indirect CP entry so it needs special handling
527 case JVM_CONSTANT_MethodType:
528 {
529 int ref_i = scratch_cp->method_type_index_at(scratch_i);
530 int new_ref_i = find_or_append_indirect_entry(scratch_cp, ref_i, merge_cp_p,
531 merge_cp_length_p);
532 if (new_ref_i != ref_i) {
533 log_trace(redefine, class, constantpool)
534 ("MethodType entry@%d ref_index change: %d to %d", *merge_cp_length_p, ref_i, new_ref_i);
535 }
536 (*merge_cp_p)->method_type_index_at_put(*merge_cp_length_p, new_ref_i);
537 if (scratch_i != *merge_cp_length_p) {
538 // The new entry in *merge_cp_p is at a different index than
539 // the new entry in scratch_cp so we need to map the index values.
540 map_index(scratch_cp, scratch_i, *merge_cp_length_p);
541 }
542 (*merge_cp_length_p)++;
543 } break;
544
545 // this is an indirect CP entry so it needs special handling
546 case JVM_CONSTANT_MethodHandle:
547 {
548 int ref_kind = scratch_cp->method_handle_ref_kind_at(scratch_i);
549 int ref_i = scratch_cp->method_handle_index_at(scratch_i);
550 int new_ref_i = find_or_append_indirect_entry(scratch_cp, ref_i, merge_cp_p,
551 merge_cp_length_p);
552 if (new_ref_i != ref_i) {
553 log_trace(redefine, class, constantpool)
554 ("MethodHandle entry@%d ref_index change: %d to %d", *merge_cp_length_p, ref_i, new_ref_i);
555 }
556 (*merge_cp_p)->method_handle_index_at_put(*merge_cp_length_p, ref_kind, new_ref_i);
557 if (scratch_i != *merge_cp_length_p) {
558 // The new entry in *merge_cp_p is at a different index than
559 // the new entry in scratch_cp so we need to map the index values.
560 map_index(scratch_cp, scratch_i, *merge_cp_length_p);
561 }
562 (*merge_cp_length_p)++;
563 } break;
564
565 // this is an indirect CP entry so it needs special handling
566 case JVM_CONSTANT_Dynamic: // fall through
567 case JVM_CONSTANT_InvokeDynamic:
568 {
569 // Index of the bootstrap specifier in the operands array
570 int old_bs_i = scratch_cp->bootstrap_methods_attribute_index(scratch_i);
571 int new_bs_i = find_or_append_operand(scratch_cp, old_bs_i, merge_cp_p,
572 merge_cp_length_p);
573 // The bootstrap method NameAndType_info index
574 int old_ref_i = scratch_cp->bootstrap_name_and_type_ref_index_at(scratch_i);
575 int new_ref_i = find_or_append_indirect_entry(scratch_cp, old_ref_i, merge_cp_p,
576 merge_cp_length_p);
577 if (new_bs_i != old_bs_i) {
578 log_trace(redefine, class, constantpool)
579 ("Dynamic entry@%d bootstrap_method_attr_index change: %d to %d",
580 *merge_cp_length_p, old_bs_i, new_bs_i);
581 }
582 if (new_ref_i != old_ref_i) {
583 log_trace(redefine, class, constantpool)
584 ("Dynamic entry@%d name_and_type_index change: %d to %d", *merge_cp_length_p, old_ref_i, new_ref_i);
585 }
586
587 if (scratch_cp->tag_at(scratch_i).is_dynamic_constant())
588 (*merge_cp_p)->dynamic_constant_at_put(*merge_cp_length_p, new_bs_i, new_ref_i);
589 else
590 (*merge_cp_p)->invoke_dynamic_at_put(*merge_cp_length_p, new_bs_i, new_ref_i);
591 if (scratch_i != *merge_cp_length_p) {
592 // The new entry in *merge_cp_p is at a different index than
593 // the new entry in scratch_cp so we need to map the index values.
594 map_index(scratch_cp, scratch_i, *merge_cp_length_p);
595 }
596 (*merge_cp_length_p)++;
597 } break;
598
599 // At this stage, Class or UnresolvedClass could be in scratch_cp, but not
600 // ClassIndex
601 case JVM_CONSTANT_ClassIndex: // fall through
602
603 // Invalid is used as the tag for the second constant pool entry
604 // occupied by JVM_CONSTANT_Double or JVM_CONSTANT_Long. It should
605 // not be seen by itself.
606 case JVM_CONSTANT_Invalid: // fall through
607
608 // At this stage, String could be here, but not StringIndex
609 case JVM_CONSTANT_StringIndex: // fall through
610
611 // At this stage JVM_CONSTANT_UnresolvedClassInError should not be
612 // here
613 case JVM_CONSTANT_UnresolvedClassInError: // fall through
614
615 default:
616 {
617 // leave a breadcrumb
618 jbyte bad_value = scratch_cp->tag_at(scratch_i).value();
619 ShouldNotReachHere();
620 } break;
621 } // end switch tag value
622 } // end append_entry()
623
624
625 u2 VM_RedefineClasses::find_or_append_indirect_entry(const constantPoolHandle& scratch_cp,
626 int ref_i, constantPoolHandle *merge_cp_p, int *merge_cp_length_p) {
627
628 int new_ref_i = ref_i;
629 bool match = (ref_i < *merge_cp_length_p) &&
630 scratch_cp->compare_entry_to(ref_i, *merge_cp_p, ref_i);
631
632 if (!match) {
633 // forward reference in *merge_cp_p or not a direct match
634 int found_i = scratch_cp->find_matching_entry(ref_i, *merge_cp_p);
635 if (found_i != 0) {
636 guarantee(found_i != ref_i, "compare_entry_to() and find_matching_entry() do not agree");
637 // Found a matching entry somewhere else in *merge_cp_p so just need a mapping entry.
638 new_ref_i = found_i;
639 map_index(scratch_cp, ref_i, found_i);
640 } else {
641 // no match found so we have to append this entry to *merge_cp_p
642 append_entry(scratch_cp, ref_i, merge_cp_p, merge_cp_length_p);
643 // The above call to append_entry() can only append one entry
644 // so the post call query of *merge_cp_length_p is only for
645 // the sake of consistency.
646 new_ref_i = *merge_cp_length_p - 1;
647 }
648 }
649
650 // constant pool indices are u2, unless the merged constant pool overflows which
651 // we don't check for.
652 return checked_cast<u2>(new_ref_i);
653 } // end find_or_append_indirect_entry()
654
655
656 // Append a bootstrap specifier into the merge_cp operands that is semantically equal
657 // to the scratch_cp operands bootstrap specifier passed by the old_bs_i index.
658 // Recursively append new merge_cp entries referenced by the new bootstrap specifier.
659 void VM_RedefineClasses::append_operand(const constantPoolHandle& scratch_cp, int old_bs_i,
660 constantPoolHandle *merge_cp_p, int *merge_cp_length_p) {
661
662 u2 old_ref_i = scratch_cp->operand_bootstrap_method_ref_index_at(old_bs_i);
663 u2 new_ref_i = find_or_append_indirect_entry(scratch_cp, old_ref_i, merge_cp_p,
664 merge_cp_length_p);
665 if (new_ref_i != old_ref_i) {
666 log_trace(redefine, class, constantpool)
667 ("operands entry@%d bootstrap method ref_index change: %d to %d", _operands_cur_length, old_ref_i, new_ref_i);
668 }
669
670 Array<u2>* merge_ops = (*merge_cp_p)->operands();
671 int new_bs_i = _operands_cur_length;
672 // We have _operands_cur_length == 0 when the merge_cp operands is empty yet.
673 // However, the operand_offset_at(0) was set in the extend_operands() call.
674 int new_base = (new_bs_i == 0) ? (*merge_cp_p)->operand_offset_at(0)
675 : (*merge_cp_p)->operand_next_offset_at(new_bs_i - 1);
676 u2 argc = scratch_cp->operand_argument_count_at(old_bs_i);
677
678 ConstantPool::operand_offset_at_put(merge_ops, _operands_cur_length, new_base);
679 merge_ops->at_put(new_base++, new_ref_i);
680 merge_ops->at_put(new_base++, argc);
681
682 for (int i = 0; i < argc; i++) {
683 u2 old_arg_ref_i = scratch_cp->operand_argument_index_at(old_bs_i, i);
684 u2 new_arg_ref_i = find_or_append_indirect_entry(scratch_cp, old_arg_ref_i, merge_cp_p,
685 merge_cp_length_p);
686 merge_ops->at_put(new_base++, new_arg_ref_i);
687 if (new_arg_ref_i != old_arg_ref_i) {
688 log_trace(redefine, class, constantpool)
689 ("operands entry@%d bootstrap method argument ref_index change: %d to %d",
690 _operands_cur_length, old_arg_ref_i, new_arg_ref_i);
691 }
692 }
693 if (old_bs_i != _operands_cur_length) {
694 // The bootstrap specifier in *merge_cp_p is at a different index than
695 // that in scratch_cp so we need to map the index values.
696 map_operand_index(old_bs_i, new_bs_i);
697 }
698 _operands_cur_length++;
699 } // end append_operand()
700
701
702 int VM_RedefineClasses::find_or_append_operand(const constantPoolHandle& scratch_cp,
703 int old_bs_i, constantPoolHandle *merge_cp_p, int *merge_cp_length_p) {
704
705 int new_bs_i = old_bs_i; // bootstrap specifier index
706 bool match = (old_bs_i < _operands_cur_length) &&
707 scratch_cp->compare_operand_to(old_bs_i, *merge_cp_p, old_bs_i);
708
709 if (!match) {
710 // forward reference in *merge_cp_p or not a direct match
711 int found_i = scratch_cp->find_matching_operand(old_bs_i, *merge_cp_p,
712 _operands_cur_length);
713 if (found_i != -1) {
714 guarantee(found_i != old_bs_i, "compare_operand_to() and find_matching_operand() disagree");
715 // found a matching operand somewhere else in *merge_cp_p so just need a mapping
716 new_bs_i = found_i;
717 map_operand_index(old_bs_i, found_i);
718 } else {
719 // no match found so we have to append this bootstrap specifier to *merge_cp_p
720 append_operand(scratch_cp, old_bs_i, merge_cp_p, merge_cp_length_p);
721 new_bs_i = _operands_cur_length - 1;
722 }
723 }
724 return new_bs_i;
725 } // end find_or_append_operand()
726
727
728 void VM_RedefineClasses::finalize_operands_merge(const constantPoolHandle& merge_cp, TRAPS) {
729 if (merge_cp->operands() == nullptr) {
730 return;
731 }
732 // Shrink the merge_cp operands
733 merge_cp->shrink_operands(_operands_cur_length, CHECK);
734
735 if (log_is_enabled(Trace, redefine, class, constantpool)) {
736 // don't want to loop unless we are tracing
737 int count = 0;
738 for (int i = 1; i < _operands_index_map_p->length(); i++) {
739 int value = _operands_index_map_p->at(i);
740 if (value != -1) {
741 log_trace(redefine, class, constantpool)("operands_index_map[%d]: old=%d new=%d", count, i, value);
742 count++;
743 }
744 }
745 }
746 // Clean-up
747 _operands_index_map_p = nullptr;
748 _operands_cur_length = 0;
749 _operands_index_map_count = 0;
750 } // end finalize_operands_merge()
751
752 // Symbol* comparator for qsort
753 // The caller must have an active ResourceMark.
754 static int symcmp(const void* a, const void* b) {
755 char* astr = (*(Symbol**)a)->as_C_string();
756 char* bstr = (*(Symbol**)b)->as_C_string();
757 return strcmp(astr, bstr);
758 }
759
760 // The caller must have an active ResourceMark.
761 static jvmtiError check_attribute_arrays(const char* attr_name,
762 InstanceKlass* the_class, InstanceKlass* scratch_class,
763 Array<u2>* the_array, Array<u2>* scr_array) {
764 bool the_array_exists = the_array != Universe::the_empty_short_array();
765 bool scr_array_exists = scr_array != Universe::the_empty_short_array();
766
767 int array_len = the_array->length();
768 if (the_array_exists && scr_array_exists) {
769 if (array_len != scr_array->length()) {
770 log_trace(redefine, class)
771 ("redefined class %s attribute change error: %s len=%d changed to len=%d",
772 the_class->external_name(), attr_name, array_len, scr_array->length());
773 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_CLASS_ATTRIBUTE_CHANGED;
774 }
775
776 // The order of entries in the attribute array is not specified so we
777 // have to explicitly check for the same contents. We do this by copying
778 // the referenced symbols into their own arrays, sorting them and then
779 // comparing each element pair.
780
781 Symbol** the_syms = NEW_RESOURCE_ARRAY_RETURN_NULL(Symbol*, array_len);
782 Symbol** scr_syms = NEW_RESOURCE_ARRAY_RETURN_NULL(Symbol*, array_len);
783
784 if (the_syms == nullptr || scr_syms == nullptr) {
785 return JVMTI_ERROR_OUT_OF_MEMORY;
786 }
787
788 for (int i = 0; i < array_len; i++) {
789 int the_cp_index = the_array->at(i);
790 int scr_cp_index = scr_array->at(i);
791 the_syms[i] = the_class->constants()->klass_name_at(the_cp_index);
792 scr_syms[i] = scratch_class->constants()->klass_name_at(scr_cp_index);
793 }
794
795 qsort(the_syms, array_len, sizeof(Symbol*), symcmp);
796 qsort(scr_syms, array_len, sizeof(Symbol*), symcmp);
797
798 for (int i = 0; i < array_len; i++) {
799 if (the_syms[i] != scr_syms[i]) {
800 log_info(redefine, class)
801 ("redefined class %s attribute change error: %s[%d]: %s changed to %s",
802 the_class->external_name(), attr_name, i,
803 the_syms[i]->as_C_string(), scr_syms[i]->as_C_string());
804 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_CLASS_ATTRIBUTE_CHANGED;
805 }
806 }
807 } else if (the_array_exists ^ scr_array_exists) {
808 const char* action_str = (the_array_exists) ? "removed" : "added";
809 log_info(redefine, class)
810 ("redefined class %s attribute change error: %s attribute %s",
811 the_class->external_name(), attr_name, action_str);
812 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_CLASS_ATTRIBUTE_CHANGED;
813 }
814 return JVMTI_ERROR_NONE;
815 }
816
817 static jvmtiError check_nest_attributes(InstanceKlass* the_class,
818 InstanceKlass* scratch_class) {
819 // Check whether the class NestHost attribute has been changed.
820 Thread* thread = Thread::current();
821 ResourceMark rm(thread);
822 u2 the_nest_host_idx = the_class->nest_host_index();
823 u2 scr_nest_host_idx = scratch_class->nest_host_index();
824
825 if (the_nest_host_idx != 0 && scr_nest_host_idx != 0) {
826 Symbol* the_sym = the_class->constants()->klass_name_at(the_nest_host_idx);
827 Symbol* scr_sym = scratch_class->constants()->klass_name_at(scr_nest_host_idx);
828 if (the_sym != scr_sym) {
829 log_info(redefine, class, nestmates)
830 ("redefined class %s attribute change error: NestHost class: %s replaced with: %s",
831 the_class->external_name(), the_sym->as_C_string(), scr_sym->as_C_string());
832 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_CLASS_ATTRIBUTE_CHANGED;
833 }
834 } else if ((the_nest_host_idx == 0) ^ (scr_nest_host_idx == 0)) {
835 const char* action_str = (the_nest_host_idx != 0) ? "removed" : "added";
836 log_info(redefine, class, nestmates)
837 ("redefined class %s attribute change error: NestHost attribute %s",
838 the_class->external_name(), action_str);
839 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_CLASS_ATTRIBUTE_CHANGED;
840 }
841
842 // Check whether the class NestMembers attribute has been changed.
843 return check_attribute_arrays("NestMembers",
844 the_class, scratch_class,
845 the_class->nest_members(),
846 scratch_class->nest_members());
847 }
848
849 // Return an error status if the class Record attribute was changed.
850 static jvmtiError check_record_attribute(InstanceKlass* the_class, InstanceKlass* scratch_class) {
851 // Get lists of record components.
852 Array<RecordComponent*>* the_record = the_class->record_components();
853 Array<RecordComponent*>* scr_record = scratch_class->record_components();
854 bool the_record_exists = the_record != nullptr;
855 bool scr_record_exists = scr_record != nullptr;
856
857 if (the_record_exists && scr_record_exists) {
858 int the_num_components = the_record->length();
859 int scr_num_components = scr_record->length();
860 if (the_num_components != scr_num_components) {
861 log_info(redefine, class, record)
862 ("redefined class %s attribute change error: Record num_components=%d changed to num_components=%d",
863 the_class->external_name(), the_num_components, scr_num_components);
864 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_CLASS_ATTRIBUTE_CHANGED;
865 }
866
867 // Compare each field in each record component.
868 ConstantPool* the_cp = the_class->constants();
869 ConstantPool* scr_cp = scratch_class->constants();
870 for (int x = 0; x < the_num_components; x++) {
871 RecordComponent* the_component = the_record->at(x);
872 RecordComponent* scr_component = scr_record->at(x);
873 const Symbol* const the_name = the_cp->symbol_at(the_component->name_index());
874 const Symbol* const scr_name = scr_cp->symbol_at(scr_component->name_index());
875 const Symbol* const the_descr = the_cp->symbol_at(the_component->descriptor_index());
876 const Symbol* const scr_descr = scr_cp->symbol_at(scr_component->descriptor_index());
877 if (the_name != scr_name || the_descr != scr_descr) {
878 log_info(redefine, class, record)
879 ("redefined class %s attribute change error: Record name_index, descriptor_index, and/or attributes_count changed",
880 the_class->external_name());
881 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_CLASS_ATTRIBUTE_CHANGED;
882 }
883
884 int the_gen_sig = the_component->generic_signature_index();
885 int scr_gen_sig = scr_component->generic_signature_index();
886 const Symbol* const the_gen_sig_sym = (the_gen_sig == 0 ? nullptr :
887 the_cp->symbol_at(the_component->generic_signature_index()));
888 const Symbol* const scr_gen_sig_sym = (scr_gen_sig == 0 ? nullptr :
889 scr_cp->symbol_at(scr_component->generic_signature_index()));
890 if (the_gen_sig_sym != scr_gen_sig_sym) {
891 log_info(redefine, class, record)
892 ("redefined class %s attribute change error: Record generic_signature attribute changed",
893 the_class->external_name());
894 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_CLASS_ATTRIBUTE_CHANGED;
895 }
896
897 // It's okay if a record component's annotations were changed.
898 }
899
900 } else if (the_record_exists ^ scr_record_exists) {
901 const char* action_str = (the_record_exists) ? "removed" : "added";
902 log_info(redefine, class, record)
903 ("redefined class %s attribute change error: Record attribute %s",
904 the_class->external_name(), action_str);
905 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_CLASS_ATTRIBUTE_CHANGED;
906 }
907
908 return JVMTI_ERROR_NONE;
909 }
910
911
912 static jvmtiError check_permitted_subclasses_attribute(InstanceKlass* the_class,
913 InstanceKlass* scratch_class) {
914 Thread* thread = Thread::current();
915 ResourceMark rm(thread);
916
917 // Check whether the class PermittedSubclasses attribute has been changed.
918 return check_attribute_arrays("PermittedSubclasses",
919 the_class, scratch_class,
920 the_class->permitted_subclasses(),
921 scratch_class->permitted_subclasses());
922 }
923
924 static bool can_add_or_delete(Method* m) {
925 // Compatibility mode
926 return (AllowRedefinitionToAddDeleteMethods &&
927 (m->is_private() && (m->is_static() || m->is_final())));
928 }
929
930 jvmtiError VM_RedefineClasses::compare_and_normalize_class_versions(
931 InstanceKlass* the_class,
932 InstanceKlass* scratch_class) {
933 int i;
934
935 // Check superclasses, or rather their names, since superclasses themselves can be
936 // requested to replace.
937 // Check for null superclass first since this might be java.lang.Object
938 if (the_class->super() != scratch_class->super() &&
939 (the_class->super() == nullptr || scratch_class->super() == nullptr ||
940 the_class->super()->name() !=
941 scratch_class->super()->name())) {
942 log_info(redefine, class, normalize)
943 ("redefined class %s superclass change error: superclass changed from %s to %s.",
944 the_class->external_name(),
945 the_class->super() == nullptr ? "null" : the_class->super()->external_name(),
946 scratch_class->super() == nullptr ? "null" : scratch_class->super()->external_name());
947 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_HIERARCHY_CHANGED;
948 }
949
950 // Check if the number, names and order of directly implemented interfaces are the same.
951 // I think in principle we should just check if the sets of names of directly implemented
952 // interfaces are the same, i.e. the order of declaration (which, however, if changed in the
953 // .java file, also changes in .class file) should not matter. However, comparing sets is
954 // technically a bit more difficult, and, more importantly, I am not sure at present that the
955 // order of interfaces does not matter on the implementation level, i.e. that the VM does not
956 // rely on it somewhere.
957 Array<InstanceKlass*>* k_interfaces = the_class->local_interfaces();
958 Array<InstanceKlass*>* k_new_interfaces = scratch_class->local_interfaces();
959 int n_intfs = k_interfaces->length();
960 if (n_intfs != k_new_interfaces->length()) {
961 log_info(redefine, class, normalize)
962 ("redefined class %s interfaces change error: number of implemented interfaces changed from %d to %d.",
963 the_class->external_name(), n_intfs, k_new_interfaces->length());
964 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_HIERARCHY_CHANGED;
965 }
966 for (i = 0; i < n_intfs; i++) {
967 if (k_interfaces->at(i)->name() !=
968 k_new_interfaces->at(i)->name()) {
969 log_info(redefine, class, normalize)
970 ("redefined class %s interfaces change error: interface changed from %s to %s.",
971 the_class->external_name(),
972 k_interfaces->at(i)->external_name(), k_new_interfaces->at(i)->external_name());
973 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_HIERARCHY_CHANGED;
974 }
975 }
976
977 // Check whether class is in the error init state.
978 if (the_class->is_in_error_state()) {
979 log_info(redefine, class, normalize)
980 ("redefined class %s is in error init state.", the_class->external_name());
981 // TBD #5057930: special error code is needed in 1.6
982 return JVMTI_ERROR_INVALID_CLASS;
983 }
984
985 // Check whether the nest-related attributes have been changed.
986 jvmtiError err = check_nest_attributes(the_class, scratch_class);
987 if (err != JVMTI_ERROR_NONE) {
988 return err;
989 }
990
991 // Check whether the Record attribute has been changed.
992 err = check_record_attribute(the_class, scratch_class);
993 if (err != JVMTI_ERROR_NONE) {
994 return err;
995 }
996
997 // Check whether the PermittedSubclasses attribute has been changed.
998 err = check_permitted_subclasses_attribute(the_class, scratch_class);
999 if (err != JVMTI_ERROR_NONE) {
1000 return err;
1001 }
1002
1003 // Check whether class modifiers are the same.
1004 jushort old_flags = (jushort) the_class->access_flags().get_flags();
1005 jushort new_flags = (jushort) scratch_class->access_flags().get_flags();
1006 if (old_flags != new_flags) {
1007 log_info(redefine, class, normalize)
1008 ("redefined class %s modifiers change error: modifiers changed from %d to %d.",
1009 the_class->external_name(), old_flags, new_flags);
1010 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_CLASS_MODIFIERS_CHANGED;
1011 }
1012
1013 // Check if the number, names, types and order of fields declared in these classes
1014 // are the same.
1015 JavaFieldStream old_fs(the_class);
1016 JavaFieldStream new_fs(scratch_class);
1017 for (; !old_fs.done() && !new_fs.done(); old_fs.next(), new_fs.next()) {
1018 // name and signature
1019 Symbol* name_sym1 = the_class->constants()->symbol_at(old_fs.name_index());
1020 Symbol* sig_sym1 = the_class->constants()->symbol_at(old_fs.signature_index());
1021 Symbol* name_sym2 = scratch_class->constants()->symbol_at(new_fs.name_index());
1022 Symbol* sig_sym2 = scratch_class->constants()->symbol_at(new_fs.signature_index());
1023 if (name_sym1 != name_sym2 || sig_sym1 != sig_sym2) {
1024 log_info(redefine, class, normalize)
1025 ("redefined class %s fields change error: field %s %s changed to %s %s.",
1026 the_class->external_name(),
1027 sig_sym1->as_C_string(), name_sym1->as_C_string(),
1028 sig_sym2->as_C_string(), name_sym2->as_C_string());
1029 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_SCHEMA_CHANGED;
1030 }
1031 // offset
1032 if (old_fs.offset() != new_fs.offset()) {
1033 log_info(redefine, class, normalize)
1034 ("redefined class %s field %s change error: offset changed from %d to %d.",
1035 the_class->external_name(), name_sym2->as_C_string(), old_fs.offset(), new_fs.offset());
1036 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_SCHEMA_CHANGED;
1037 }
1038 // access
1039 old_flags = old_fs.access_flags().as_short();
1040 new_flags = new_fs.access_flags().as_short();
1041 if ((old_flags ^ new_flags) & JVM_RECOGNIZED_FIELD_MODIFIERS) {
1042 log_info(redefine, class, normalize)
1043 ("redefined class %s field %s change error: modifiers changed from %d to %d.",
1044 the_class->external_name(), name_sym2->as_C_string(), old_flags, new_flags);
1045 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_SCHEMA_CHANGED;
1046 }
1047 }
1048
1049 // If both streams aren't done then we have a differing number of
1050 // fields.
1051 if (!old_fs.done() || !new_fs.done()) {
1052 const char* action = old_fs.done() ? "added" : "deleted";
1053 log_info(redefine, class, normalize)
1054 ("redefined class %s fields change error: some fields were %s.",
1055 the_class->external_name(), action);
1056 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_SCHEMA_CHANGED;
1057 }
1058
1059 // Do a parallel walk through the old and new methods. Detect
1060 // cases where they match (exist in both), have been added in
1061 // the new methods, or have been deleted (exist only in the
1062 // old methods). The class file parser places methods in order
1063 // by method name, but does not order overloaded methods by
1064 // signature. In order to determine what fate befell the methods,
1065 // this code places the overloaded new methods that have matching
1066 // old methods in the same order as the old methods and places
1067 // new overloaded methods at the end of overloaded methods of
1068 // that name. The code for this order normalization is adapted
1069 // from the algorithm used in InstanceKlass::find_method().
1070 // Since we are swapping out of order entries as we find them,
1071 // we only have to search forward through the overloaded methods.
1072 // Methods which are added and have the same name as an existing
1073 // method (but different signature) will be put at the end of
1074 // the methods with that name, and the name mismatch code will
1075 // handle them.
1076 Array<Method*>* k_old_methods(the_class->methods());
1077 Array<Method*>* k_new_methods(scratch_class->methods());
1078 int n_old_methods = k_old_methods->length();
1079 int n_new_methods = k_new_methods->length();
1080 Thread* thread = Thread::current();
1081
1082 int ni = 0;
1083 int oi = 0;
1084 while (true) {
1085 Method* k_old_method;
1086 Method* k_new_method;
1087 enum { matched, added, deleted, undetermined } method_was = undetermined;
1088
1089 if (oi >= n_old_methods) {
1090 if (ni >= n_new_methods) {
1091 break; // we've looked at everything, done
1092 }
1093 // New method at the end
1094 k_new_method = k_new_methods->at(ni);
1095 method_was = added;
1096 } else if (ni >= n_new_methods) {
1097 // Old method, at the end, is deleted
1098 k_old_method = k_old_methods->at(oi);
1099 method_was = deleted;
1100 } else {
1101 // There are more methods in both the old and new lists
1102 k_old_method = k_old_methods->at(oi);
1103 k_new_method = k_new_methods->at(ni);
1104 if (k_old_method->name() != k_new_method->name()) {
1105 // Methods are sorted by method name, so a mismatch means added
1106 // or deleted
1107 if (k_old_method->name()->fast_compare(k_new_method->name()) > 0) {
1108 method_was = added;
1109 } else {
1110 method_was = deleted;
1111 }
1112 } else if (k_old_method->signature() == k_new_method->signature()) {
1113 // Both the name and signature match
1114 method_was = matched;
1115 } else {
1116 // The name matches, but the signature doesn't, which means we have to
1117 // search forward through the new overloaded methods.
1118 int nj; // outside the loop for post-loop check
1119 for (nj = ni + 1; nj < n_new_methods; nj++) {
1120 Method* m = k_new_methods->at(nj);
1121 if (k_old_method->name() != m->name()) {
1122 // reached another method name so no more overloaded methods
1123 method_was = deleted;
1124 break;
1125 }
1126 if (k_old_method->signature() == m->signature()) {
1127 // found a match so swap the methods
1128 k_new_methods->at_put(ni, m);
1129 k_new_methods->at_put(nj, k_new_method);
1130 k_new_method = m;
1131 method_was = matched;
1132 break;
1133 }
1134 }
1135
1136 if (nj >= n_new_methods) {
1137 // reached the end without a match; so method was deleted
1138 method_was = deleted;
1139 }
1140 }
1141 }
1142
1143 switch (method_was) {
1144 case matched:
1145 // methods match, be sure modifiers do too
1146 old_flags = (jushort) k_old_method->access_flags().get_flags();
1147 new_flags = (jushort) k_new_method->access_flags().get_flags();
1148 if ((old_flags ^ new_flags) & ~(JVM_ACC_NATIVE)) {
1149 log_info(redefine, class, normalize)
1150 ("redefined class %s method %s modifiers error: modifiers changed from %d to %d",
1151 the_class->external_name(), k_old_method->name_and_sig_as_C_string(), old_flags, new_flags);
1152 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_METHOD_MODIFIERS_CHANGED;
1153 }
1154 {
1155 u2 new_num = k_new_method->method_idnum();
1156 u2 old_num = k_old_method->method_idnum();
1157 if (new_num != old_num) {
1158 Method* idnum_owner = scratch_class->method_with_idnum(old_num);
1159 if (idnum_owner != nullptr) {
1160 // There is already a method assigned this idnum -- switch them
1161 // Take current and original idnum from the new_method
1162 idnum_owner->set_method_idnum(new_num);
1163 idnum_owner->set_orig_method_idnum(k_new_method->orig_method_idnum());
1164 }
1165 // Take current and original idnum from the old_method
1166 k_new_method->set_method_idnum(old_num);
1167 k_new_method->set_orig_method_idnum(k_old_method->orig_method_idnum());
1168 if (thread->has_pending_exception()) {
1169 return JVMTI_ERROR_OUT_OF_MEMORY;
1170 }
1171 }
1172 }
1173 log_trace(redefine, class, normalize)
1174 ("Method matched: new: %s [%d] == old: %s [%d]",
1175 k_new_method->name_and_sig_as_C_string(), ni, k_old_method->name_and_sig_as_C_string(), oi);
1176 // advance to next pair of methods
1177 ++oi;
1178 ++ni;
1179 break;
1180 case added:
1181 // method added, see if it is OK
1182 if (!can_add_or_delete(k_new_method)) {
1183 log_info(redefine, class, normalize)
1184 ("redefined class %s methods error: added method: %s [%d]",
1185 the_class->external_name(), k_new_method->name_and_sig_as_C_string(), ni);
1186 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_METHOD_ADDED;
1187 }
1188 {
1189 u2 num = the_class->next_method_idnum();
1190 if (num == ConstMethod::UNSET_IDNUM) {
1191 // cannot add any more methods
1192 log_info(redefine, class, normalize)
1193 ("redefined class %s methods error: can't create ID for new method %s [%d]",
1194 the_class->external_name(), k_new_method->name_and_sig_as_C_string(), ni);
1195 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_METHOD_ADDED;
1196 }
1197 u2 new_num = k_new_method->method_idnum();
1198 Method* idnum_owner = scratch_class->method_with_idnum(num);
1199 if (idnum_owner != nullptr) {
1200 // There is already a method assigned this idnum -- switch them
1201 // Take current and original idnum from the new_method
1202 idnum_owner->set_method_idnum(new_num);
1203 idnum_owner->set_orig_method_idnum(k_new_method->orig_method_idnum());
1204 }
1205 k_new_method->set_method_idnum(num);
1206 k_new_method->set_orig_method_idnum(num);
1207 if (thread->has_pending_exception()) {
1208 return JVMTI_ERROR_OUT_OF_MEMORY;
1209 }
1210 }
1211 log_trace(redefine, class, normalize)
1212 ("Method added: new: %s [%d]", k_new_method->name_and_sig_as_C_string(), ni);
1213 ++ni; // advance to next new method
1214 break;
1215 case deleted:
1216 // method deleted, see if it is OK
1217 if (!can_add_or_delete(k_old_method)) {
1218 log_info(redefine, class, normalize)
1219 ("redefined class %s methods error: deleted method %s [%d]",
1220 the_class->external_name(), k_old_method->name_and_sig_as_C_string(), oi);
1221 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_METHOD_DELETED;
1222 }
1223 log_trace(redefine, class, normalize)
1224 ("Method deleted: old: %s [%d]", k_old_method->name_and_sig_as_C_string(), oi);
1225 ++oi; // advance to next old method
1226 break;
1227 default:
1228 ShouldNotReachHere();
1229 }
1230 }
1231
1232 return JVMTI_ERROR_NONE;
1233 }
1234
1235
1236 // Find new constant pool index value for old constant pool index value
1237 // by searching the index map. Returns zero (0) if there is no mapped
1238 // value for the old constant pool index.
1239 u2 VM_RedefineClasses::find_new_index(int old_index) {
1240 if (_index_map_count == 0) {
1241 // map is empty so nothing can be found
1242 return 0;
1243 }
1244
1245 if (old_index < 1 || old_index >= _index_map_p->length()) {
1246 // The old_index is out of range so it is not mapped. This should
1247 // not happen in regular constant pool merging use, but it can
1248 // happen if a corrupt annotation is processed.
1249 return 0;
1250 }
1251
1252 int value = _index_map_p->at(old_index);
1253 if (value == -1) {
1254 // the old_index is not mapped
1255 return 0;
1256 }
1257
1258 // constant pool indices are u2, unless the merged constant pool overflows which
1259 // we don't check for.
1260 return checked_cast<u2>(value);
1261 } // end find_new_index()
1262
1263
1264 // Find new bootstrap specifier index value for old bootstrap specifier index
1265 // value by searching the index map. Returns unused index (-1) if there is
1266 // no mapped value for the old bootstrap specifier index.
1267 int VM_RedefineClasses::find_new_operand_index(int old_index) {
1268 if (_operands_index_map_count == 0) {
1269 // map is empty so nothing can be found
1270 return -1;
1271 }
1272
1273 if (old_index == -1 || old_index >= _operands_index_map_p->length()) {
1274 // The old_index is out of range so it is not mapped.
1275 // This should not happen in regular constant pool merging use.
1276 return -1;
1277 }
1278
1279 int value = _operands_index_map_p->at(old_index);
1280 if (value == -1) {
1281 // the old_index is not mapped
1282 return -1;
1283 }
1284
1285 return value;
1286 } // end find_new_operand_index()
1287
1288
1289 // Returns true if the current mismatch is due to a resolved/unresolved
1290 // class pair. Otherwise, returns false.
1291 bool VM_RedefineClasses::is_unresolved_class_mismatch(const constantPoolHandle& cp1,
1292 int index1, const constantPoolHandle& cp2, int index2) {
1293
1294 jbyte t1 = cp1->tag_at(index1).value();
1295 if (t1 != JVM_CONSTANT_Class && t1 != JVM_CONSTANT_UnresolvedClass) {
1296 return false; // wrong entry type; not our special case
1297 }
1298
1299 jbyte t2 = cp2->tag_at(index2).value();
1300 if (t2 != JVM_CONSTANT_Class && t2 != JVM_CONSTANT_UnresolvedClass) {
1301 return false; // wrong entry type; not our special case
1302 }
1303
1304 if (t1 == t2) {
1305 return false; // not a mismatch; not our special case
1306 }
1307
1308 char *s1 = cp1->klass_name_at(index1)->as_C_string();
1309 char *s2 = cp2->klass_name_at(index2)->as_C_string();
1310 if (strcmp(s1, s2) != 0) {
1311 return false; // strings don't match; not our special case
1312 }
1313
1314 return true; // made it through the gauntlet; this is our special case
1315 } // end is_unresolved_class_mismatch()
1316
1317
1318 // The bug 6214132 caused the verification to fail.
1319 // 1. What's done in RedefineClasses() before verification:
1320 // a) A reference to the class being redefined (_the_class) and a
1321 // reference to new version of the class (_scratch_class) are
1322 // saved here for use during the bytecode verification phase of
1323 // RedefineClasses.
1324 // b) The _java_mirror field from _the_class is copied to the
1325 // _java_mirror field in _scratch_class. This means that a jclass
1326 // returned for _the_class or _scratch_class will refer to the
1327 // same Java mirror. The verifier will see the "one true mirror"
1328 // for the class being verified.
1329 // 2. See comments in JvmtiThreadState for what is done during verification.
1330
1331 class RedefineVerifyMark : public StackObj {
1332 private:
1333 JvmtiThreadState* _state;
1334 Klass* _scratch_class;
1335 OopHandle _scratch_mirror;
1336
1337 public:
1338
1339 RedefineVerifyMark(Klass* the_class, Klass* scratch_class,
1340 JvmtiThreadState* state) : _state(state), _scratch_class(scratch_class)
1341 {
1342 _state->set_class_versions_map(the_class, scratch_class);
1343 _scratch_mirror = the_class->java_mirror_handle(); // this is a copy that is swapped
1344 _scratch_class->swap_java_mirror_handle(_scratch_mirror);
1345 }
1346
1347 ~RedefineVerifyMark() {
1348 // Restore the scratch class's mirror, so when scratch_class is removed
1349 // the correct mirror pointing to it can be cleared.
1350 _scratch_class->swap_java_mirror_handle(_scratch_mirror);
1351 _state->clear_class_versions_map();
1352 }
1353 };
1354
1355
1356 jvmtiError VM_RedefineClasses::load_new_class_versions() {
1357
1358 // For consistency allocate memory using os::malloc wrapper.
1359 _scratch_classes = (InstanceKlass**)
1360 os::malloc(sizeof(InstanceKlass*) * _class_count, mtClass);
1361 if (_scratch_classes == nullptr) {
1362 return JVMTI_ERROR_OUT_OF_MEMORY;
1363 }
1364 // Zero initialize the _scratch_classes array.
1365 for (int i = 0; i < _class_count; i++) {
1366 _scratch_classes[i] = nullptr;
1367 }
1368
1369 JavaThread* current = JavaThread::current();
1370 ResourceMark rm(current);
1371
1372 JvmtiThreadState *state = JvmtiThreadState::state_for(current);
1373 // state can only be null if the current thread is exiting which
1374 // should not happen since we're trying to do a RedefineClasses
1375 guarantee(state != nullptr, "exiting thread calling load_new_class_versions");
1376 for (int i = 0; i < _class_count; i++) {
1377 // Create HandleMark so that any handles created while loading new class
1378 // versions are deleted. Constant pools are deallocated while merging
1379 // constant pools
1380 HandleMark hm(current);
1381 InstanceKlass* the_class = get_ik(_class_defs[i].klass);
1382
1383 log_debug(redefine, class, load)
1384 ("loading name=%s kind=%d (avail_mem=" UINT64_FORMAT "K)",
1385 the_class->external_name(), _class_load_kind, os::available_memory() >> 10);
1386
1387 ClassFileStream st((u1*)_class_defs[i].class_bytes,
1388 _class_defs[i].class_byte_count,
1389 "__VM_RedefineClasses__",
1390 ClassFileStream::verify);
1391
1392 // Set redefined class handle in JvmtiThreadState class.
1393 // This redefined class is sent to agent event handler for class file
1394 // load hook event.
1395 state->set_class_being_redefined(the_class, _class_load_kind);
1396
1397 JavaThread* THREAD = current; // For exception macros.
1398 ExceptionMark em(THREAD);
1399 Handle protection_domain(THREAD, the_class->protection_domain());
1400 ClassLoadInfo cl_info(protection_domain);
1401 // Parse and create a class from the bytes, but this class isn't added
1402 // to the dictionary, so do not call resolve_from_stream.
1403 InstanceKlass* scratch_class = KlassFactory::create_from_stream(&st,
1404 the_class->name(),
1405 the_class->class_loader_data(),
1406 cl_info,
1407 THREAD);
1408
1409 // Clear class_being_redefined just to be sure.
1410 state->clear_class_being_redefined();
1411
1412 // TODO: if this is retransform, and nothing changed we can skip it
1413
1414 // Need to clean up allocated InstanceKlass if there's an error so assign
1415 // the result here. Caller deallocates all the scratch classes in case of
1416 // an error.
1417 _scratch_classes[i] = scratch_class;
1418
1419 if (HAS_PENDING_EXCEPTION) {
1420 Symbol* ex_name = PENDING_EXCEPTION->klass()->name();
1421 log_info(redefine, class, load, exceptions)("create_from_stream exception: '%s'", ex_name->as_C_string());
1422 CLEAR_PENDING_EXCEPTION;
1423
1424 if (ex_name == vmSymbols::java_lang_UnsupportedClassVersionError()) {
1425 return JVMTI_ERROR_UNSUPPORTED_VERSION;
1426 } else if (ex_name == vmSymbols::java_lang_ClassFormatError()) {
1427 return JVMTI_ERROR_INVALID_CLASS_FORMAT;
1428 } else if (ex_name == vmSymbols::java_lang_ClassCircularityError()) {
1429 return JVMTI_ERROR_CIRCULAR_CLASS_DEFINITION;
1430 } else if (ex_name == vmSymbols::java_lang_NoClassDefFoundError()) {
1431 // The message will be "XXX (wrong name: YYY)"
1432 return JVMTI_ERROR_NAMES_DONT_MATCH;
1433 } else if (ex_name == vmSymbols::java_lang_OutOfMemoryError()) {
1434 return JVMTI_ERROR_OUT_OF_MEMORY;
1435 } else { // Just in case more exceptions can be thrown..
1436 return JVMTI_ERROR_FAILS_VERIFICATION;
1437 }
1438 }
1439
1440 // Ensure class is linked before redefine
1441 if (!the_class->is_linked()) {
1442 the_class->link_class(THREAD);
1443 if (HAS_PENDING_EXCEPTION) {
1444 Symbol* ex_name = PENDING_EXCEPTION->klass()->name();
1445 oop message = java_lang_Throwable::message(PENDING_EXCEPTION);
1446 if (message != nullptr) {
1447 char* ex_msg = java_lang_String::as_utf8_string(message);
1448 log_info(redefine, class, load, exceptions)("link_class exception: '%s %s'",
1449 ex_name->as_C_string(), ex_msg);
1450 } else {
1451 log_info(redefine, class, load, exceptions)("link_class exception: '%s'",
1452 ex_name->as_C_string());
1453 }
1454 CLEAR_PENDING_EXCEPTION;
1455 if (ex_name == vmSymbols::java_lang_OutOfMemoryError()) {
1456 return JVMTI_ERROR_OUT_OF_MEMORY;
1457 } else if (ex_name == vmSymbols::java_lang_NoClassDefFoundError()) {
1458 return JVMTI_ERROR_INVALID_CLASS;
1459 } else {
1460 return JVMTI_ERROR_INTERNAL;
1461 }
1462 }
1463 }
1464
1465 // Do the validity checks in compare_and_normalize_class_versions()
1466 // before verifying the byte codes. By doing these checks first, we
1467 // limit the number of functions that require redirection from
1468 // the_class to scratch_class. In particular, we don't have to
1469 // modify JNI GetSuperclass() and thus won't change its performance.
1470 jvmtiError res = compare_and_normalize_class_versions(the_class,
1471 scratch_class);
1472 if (res != JVMTI_ERROR_NONE) {
1473 return res;
1474 }
1475
1476 // verify what the caller passed us
1477 {
1478 // The bug 6214132 caused the verification to fail.
1479 // Information about the_class and scratch_class is temporarily
1480 // recorded into jvmtiThreadState. This data is used to redirect
1481 // the_class to scratch_class in the JVM_* functions called by the
1482 // verifier. Please, refer to jvmtiThreadState.hpp for the detailed
1483 // description.
1484 RedefineVerifyMark rvm(the_class, scratch_class, state);
1485 Verifier::verify(scratch_class, true, THREAD);
1486 }
1487
1488 if (HAS_PENDING_EXCEPTION) {
1489 Symbol* ex_name = PENDING_EXCEPTION->klass()->name();
1490 log_info(redefine, class, load, exceptions)("verify_byte_codes exception: '%s'", ex_name->as_C_string());
1491 CLEAR_PENDING_EXCEPTION;
1492 if (ex_name == vmSymbols::java_lang_OutOfMemoryError()) {
1493 return JVMTI_ERROR_OUT_OF_MEMORY;
1494 } else {
1495 // tell the caller the bytecodes are bad
1496 return JVMTI_ERROR_FAILS_VERIFICATION;
1497 }
1498 }
1499
1500 res = merge_cp_and_rewrite(the_class, scratch_class, THREAD);
1501 if (HAS_PENDING_EXCEPTION) {
1502 Symbol* ex_name = PENDING_EXCEPTION->klass()->name();
1503 log_info(redefine, class, load, exceptions)("merge_cp_and_rewrite exception: '%s'", ex_name->as_C_string());
1504 CLEAR_PENDING_EXCEPTION;
1505 if (ex_name == vmSymbols::java_lang_OutOfMemoryError()) {
1506 return JVMTI_ERROR_OUT_OF_MEMORY;
1507 } else {
1508 return JVMTI_ERROR_INTERNAL;
1509 }
1510 }
1511
1512 #ifdef ASSERT
1513 {
1514 // verify what we have done during constant pool merging
1515 {
1516 RedefineVerifyMark rvm(the_class, scratch_class, state);
1517 Verifier::verify(scratch_class, true, THREAD);
1518 }
1519
1520 if (HAS_PENDING_EXCEPTION) {
1521 Symbol* ex_name = PENDING_EXCEPTION->klass()->name();
1522 log_info(redefine, class, load, exceptions)
1523 ("verify_byte_codes post merge-CP exception: '%s'", ex_name->as_C_string());
1524 CLEAR_PENDING_EXCEPTION;
1525 if (ex_name == vmSymbols::java_lang_OutOfMemoryError()) {
1526 return JVMTI_ERROR_OUT_OF_MEMORY;
1527 } else {
1528 // tell the caller that constant pool merging screwed up
1529 return JVMTI_ERROR_INTERNAL;
1530 }
1531 }
1532 }
1533 #endif // ASSERT
1534
1535 Rewriter::rewrite(scratch_class, THREAD);
1536 if (!HAS_PENDING_EXCEPTION) {
1537 scratch_class->link_methods(THREAD);
1538 }
1539 if (HAS_PENDING_EXCEPTION) {
1540 Symbol* ex_name = PENDING_EXCEPTION->klass()->name();
1541 log_info(redefine, class, load, exceptions)
1542 ("Rewriter::rewrite or link_methods exception: '%s'", ex_name->as_C_string());
1543 CLEAR_PENDING_EXCEPTION;
1544 if (ex_name == vmSymbols::java_lang_OutOfMemoryError()) {
1545 return JVMTI_ERROR_OUT_OF_MEMORY;
1546 } else {
1547 return JVMTI_ERROR_INTERNAL;
1548 }
1549 }
1550
1551 log_debug(redefine, class, load)
1552 ("loaded name=%s (avail_mem=" UINT64_FORMAT "K)", the_class->external_name(), os::available_memory() >> 10);
1553 }
1554
1555 return JVMTI_ERROR_NONE;
1556 }
1557
1558
1559 // Map old_index to new_index as needed. scratch_cp is only needed
1560 // for log calls.
1561 void VM_RedefineClasses::map_index(const constantPoolHandle& scratch_cp,
1562 int old_index, int new_index) {
1563 if (find_new_index(old_index) != 0) {
1564 // old_index is already mapped
1565 return;
1566 }
1567
1568 if (old_index == new_index) {
1569 // no mapping is needed
1570 return;
1571 }
1572
1573 _index_map_p->at_put(old_index, new_index);
1574 _index_map_count++;
1575
1576 log_trace(redefine, class, constantpool)
1577 ("mapped tag %d at index %d to %d", scratch_cp->tag_at(old_index).value(), old_index, new_index);
1578 } // end map_index()
1579
1580
1581 // Map old_index to new_index as needed.
1582 void VM_RedefineClasses::map_operand_index(int old_index, int new_index) {
1583 if (find_new_operand_index(old_index) != -1) {
1584 // old_index is already mapped
1585 return;
1586 }
1587
1588 if (old_index == new_index) {
1589 // no mapping is needed
1590 return;
1591 }
1592
1593 _operands_index_map_p->at_put(old_index, new_index);
1594 _operands_index_map_count++;
1595
1596 log_trace(redefine, class, constantpool)("mapped bootstrap specifier at index %d to %d", old_index, new_index);
1597 } // end map_index()
1598
1599
1600 // Merge old_cp and scratch_cp and return the results of the merge via
1601 // merge_cp_p. The number of entries in *merge_cp_p is returned via
1602 // merge_cp_length_p. The entries in old_cp occupy the same locations
1603 // in *merge_cp_p. Also creates a map of indices from entries in
1604 // scratch_cp to the corresponding entry in *merge_cp_p. Index map
1605 // entries are only created for entries in scratch_cp that occupy a
1606 // different location in *merged_cp_p.
1607 bool VM_RedefineClasses::merge_constant_pools(const constantPoolHandle& old_cp,
1608 const constantPoolHandle& scratch_cp, constantPoolHandle *merge_cp_p,
1609 int *merge_cp_length_p, TRAPS) {
1610
1611 if (merge_cp_p == nullptr) {
1612 assert(false, "caller must provide scratch constantPool");
1613 return false; // robustness
1614 }
1615 if (merge_cp_length_p == nullptr) {
1616 assert(false, "caller must provide scratch CP length");
1617 return false; // robustness
1618 }
1619 // Worst case we need old_cp->length() + scratch_cp()->length(),
1620 // but the caller might be smart so make sure we have at least
1621 // the minimum.
1622 if ((*merge_cp_p)->length() < old_cp->length()) {
1623 assert(false, "merge area too small");
1624 return false; // robustness
1625 }
1626
1627 log_info(redefine, class, constantpool)("old_cp_len=%d, scratch_cp_len=%d", old_cp->length(), scratch_cp->length());
1628
1629 {
1630 // Pass 0:
1631 // The old_cp is copied to *merge_cp_p; this means that any code
1632 // using old_cp does not have to change. This work looks like a
1633 // perfect fit for ConstantPool*::copy_cp_to(), but we need to
1634 // handle one special case:
1635 // - revert JVM_CONSTANT_Class to JVM_CONSTANT_UnresolvedClass
1636 // This will make verification happy.
1637
1638 int old_i; // index into old_cp
1639
1640 // index zero (0) is not used in constantPools
1641 for (old_i = 1; old_i < old_cp->length(); old_i++) {
1642 // leave debugging crumb
1643 jbyte old_tag = old_cp->tag_at(old_i).value();
1644 switch (old_tag) {
1645 case JVM_CONSTANT_Class:
1646 case JVM_CONSTANT_UnresolvedClass:
1647 // revert the copy to JVM_CONSTANT_UnresolvedClass
1648 // May be resolving while calling this so do the same for
1649 // JVM_CONSTANT_UnresolvedClass (klass_name_at() deals with transition)
1650 (*merge_cp_p)->temp_unresolved_klass_at_put(old_i,
1651 old_cp->klass_name_index_at(old_i));
1652 break;
1653
1654 case JVM_CONSTANT_Double:
1655 case JVM_CONSTANT_Long:
1656 // just copy the entry to *merge_cp_p, but double and long take
1657 // two constant pool entries
1658 ConstantPool::copy_entry_to(old_cp, old_i, *merge_cp_p, old_i);
1659 old_i++;
1660 break;
1661
1662 default:
1663 // just copy the entry to *merge_cp_p
1664 ConstantPool::copy_entry_to(old_cp, old_i, *merge_cp_p, old_i);
1665 break;
1666 }
1667 } // end for each old_cp entry
1668
1669 ConstantPool::copy_operands(old_cp, *merge_cp_p, CHECK_false);
1670 (*merge_cp_p)->extend_operands(scratch_cp, CHECK_false);
1671
1672 // We don't need to sanity check that *merge_cp_length_p is within
1673 // *merge_cp_p bounds since we have the minimum on-entry check above.
1674 (*merge_cp_length_p) = old_i;
1675 }
1676
1677 // merge_cp_len should be the same as old_cp->length() at this point
1678 // so this trace message is really a "warm-and-breathing" message.
1679 log_debug(redefine, class, constantpool)("after pass 0: merge_cp_len=%d", *merge_cp_length_p);
1680
1681 int scratch_i; // index into scratch_cp
1682 {
1683 // Pass 1a:
1684 // Compare scratch_cp entries to the old_cp entries that we have
1685 // already copied to *merge_cp_p. In this pass, we are eliminating
1686 // exact duplicates (matching entry at same index) so we only
1687 // compare entries in the common indice range.
1688 int increment = 1;
1689 int pass1a_length = MIN2(old_cp->length(), scratch_cp->length());
1690 for (scratch_i = 1; scratch_i < pass1a_length; scratch_i += increment) {
1691 switch (scratch_cp->tag_at(scratch_i).value()) {
1692 case JVM_CONSTANT_Double:
1693 case JVM_CONSTANT_Long:
1694 // double and long take two constant pool entries
1695 increment = 2;
1696 break;
1697
1698 default:
1699 increment = 1;
1700 break;
1701 }
1702
1703 bool match = scratch_cp->compare_entry_to(scratch_i, *merge_cp_p, scratch_i);
1704 if (match) {
1705 // found a match at the same index so nothing more to do
1706 continue;
1707 } else if (is_unresolved_class_mismatch(scratch_cp, scratch_i,
1708 *merge_cp_p, scratch_i)) {
1709 // The mismatch in compare_entry_to() above is because of a
1710 // resolved versus unresolved class entry at the same index
1711 // with the same string value. Since Pass 0 reverted any
1712 // class entries to unresolved class entries in *merge_cp_p,
1713 // we go with the unresolved class entry.
1714 continue;
1715 }
1716
1717 int found_i = scratch_cp->find_matching_entry(scratch_i, *merge_cp_p);
1718 if (found_i != 0) {
1719 guarantee(found_i != scratch_i,
1720 "compare_entry_to() and find_matching_entry() do not agree");
1721
1722 // Found a matching entry somewhere else in *merge_cp_p so
1723 // just need a mapping entry.
1724 map_index(scratch_cp, scratch_i, found_i);
1725 continue;
1726 }
1727
1728 // The find_matching_entry() call above could fail to find a match
1729 // due to a resolved versus unresolved class or string entry situation
1730 // like we solved above with the is_unresolved_*_mismatch() calls.
1731 // However, we would have to call is_unresolved_*_mismatch() over
1732 // all of *merge_cp_p (potentially) and that doesn't seem to be
1733 // worth the time.
1734
1735 // No match found so we have to append this entry and any unique
1736 // referenced entries to *merge_cp_p.
1737 append_entry(scratch_cp, scratch_i, merge_cp_p, merge_cp_length_p);
1738 }
1739 }
1740
1741 log_debug(redefine, class, constantpool)
1742 ("after pass 1a: merge_cp_len=%d, scratch_i=%d, index_map_len=%d",
1743 *merge_cp_length_p, scratch_i, _index_map_count);
1744
1745 if (scratch_i < scratch_cp->length()) {
1746 // Pass 1b:
1747 // old_cp is smaller than scratch_cp so there are entries in
1748 // scratch_cp that we have not yet processed. We take care of
1749 // those now.
1750 int increment = 1;
1751 for (; scratch_i < scratch_cp->length(); scratch_i += increment) {
1752 switch (scratch_cp->tag_at(scratch_i).value()) {
1753 case JVM_CONSTANT_Double:
1754 case JVM_CONSTANT_Long:
1755 // double and long take two constant pool entries
1756 increment = 2;
1757 break;
1758
1759 default:
1760 increment = 1;
1761 break;
1762 }
1763
1764 int found_i =
1765 scratch_cp->find_matching_entry(scratch_i, *merge_cp_p);
1766 if (found_i != 0) {
1767 // Found a matching entry somewhere else in *merge_cp_p so
1768 // just need a mapping entry.
1769 map_index(scratch_cp, scratch_i, found_i);
1770 continue;
1771 }
1772
1773 // No match found so we have to append this entry and any unique
1774 // referenced entries to *merge_cp_p.
1775 append_entry(scratch_cp, scratch_i, merge_cp_p, merge_cp_length_p);
1776 }
1777
1778 log_debug(redefine, class, constantpool)
1779 ("after pass 1b: merge_cp_len=%d, scratch_i=%d, index_map_len=%d",
1780 *merge_cp_length_p, scratch_i, _index_map_count);
1781 }
1782 finalize_operands_merge(*merge_cp_p, CHECK_false);
1783
1784 return true;
1785 } // end merge_constant_pools()
1786
1787
1788 // Scoped object to clean up the constant pool(s) created for merging
1789 class MergeCPCleaner {
1790 ClassLoaderData* _loader_data;
1791 ConstantPool* _cp;
1792 ConstantPool* _scratch_cp;
1793 public:
1794 MergeCPCleaner(ClassLoaderData* loader_data, ConstantPool* merge_cp) :
1795 _loader_data(loader_data), _cp(merge_cp), _scratch_cp(nullptr) {}
1796 ~MergeCPCleaner() {
1797 _loader_data->add_to_deallocate_list(_cp);
1798 if (_scratch_cp != nullptr) {
1799 _loader_data->add_to_deallocate_list(_scratch_cp);
1800 }
1801 }
1802 void add_scratch_cp(ConstantPool* scratch_cp) { _scratch_cp = scratch_cp; }
1803 };
1804
1805 // Merge constant pools between the_class and scratch_class and
1806 // potentially rewrite bytecodes in scratch_class to use the merged
1807 // constant pool.
1808 jvmtiError VM_RedefineClasses::merge_cp_and_rewrite(
1809 InstanceKlass* the_class, InstanceKlass* scratch_class,
1810 TRAPS) {
1811 // worst case merged constant pool length is old and new combined
1812 int merge_cp_length = the_class->constants()->length()
1813 + scratch_class->constants()->length();
1814
1815 // Constant pools are not easily reused so we allocate a new one
1816 // each time.
1817 // merge_cp is created unsafe for concurrent GC processing. It
1818 // should be marked safe before discarding it. Even though
1819 // garbage, if it crosses a card boundary, it may be scanned
1820 // in order to find the start of the first complete object on the card.
1821 ClassLoaderData* loader_data = the_class->class_loader_data();
1822 ConstantPool* merge_cp_oop =
1823 ConstantPool::allocate(loader_data,
1824 merge_cp_length,
1825 CHECK_(JVMTI_ERROR_OUT_OF_MEMORY));
1826 MergeCPCleaner cp_cleaner(loader_data, merge_cp_oop);
1827
1828 HandleMark hm(THREAD); // make sure handles are cleared before
1829 // MergeCPCleaner clears out merge_cp_oop
1830 constantPoolHandle merge_cp(THREAD, merge_cp_oop);
1831
1832 // Get constants() from the old class because it could have been rewritten
1833 // while we were at a safepoint allocating a new constant pool.
1834 constantPoolHandle old_cp(THREAD, the_class->constants());
1835 constantPoolHandle scratch_cp(THREAD, scratch_class->constants());
1836
1837 // If the length changed, the class was redefined out from under us. Return
1838 // an error.
1839 if (merge_cp_length != the_class->constants()->length()
1840 + scratch_class->constants()->length()) {
1841 return JVMTI_ERROR_INTERNAL;
1842 }
1843
1844 // Update the version number of the constant pools (may keep scratch_cp)
1845 merge_cp->increment_and_save_version(old_cp->version());
1846 scratch_cp->increment_and_save_version(old_cp->version());
1847
1848 ResourceMark rm(THREAD);
1849 _index_map_count = 0;
1850 _index_map_p = new intArray(scratch_cp->length(), scratch_cp->length(), -1);
1851
1852 _operands_cur_length = ConstantPool::operand_array_length(old_cp->operands());
1853 _operands_index_map_count = 0;
1854 int operands_index_map_len = ConstantPool::operand_array_length(scratch_cp->operands());
1855 _operands_index_map_p = new intArray(operands_index_map_len, operands_index_map_len, -1);
1856
1857 // reference to the cp holder is needed for copy_operands()
1858 merge_cp->set_pool_holder(scratch_class);
1859 bool result = merge_constant_pools(old_cp, scratch_cp, &merge_cp,
1860 &merge_cp_length, THREAD);
1861 merge_cp->set_pool_holder(nullptr);
1862
1863 if (!result) {
1864 // The merge can fail due to memory allocation failure or due
1865 // to robustness checks.
1866 return JVMTI_ERROR_INTERNAL;
1867 }
1868
1869 // Set dynamic constants attribute from the original CP.
1870 if (old_cp->has_dynamic_constant()) {
1871 scratch_cp->set_has_dynamic_constant();
1872 }
1873
1874 log_info(redefine, class, constantpool)("merge_cp_len=%d, index_map_len=%d", merge_cp_length, _index_map_count);
1875
1876 if (_index_map_count == 0) {
1877 // there is nothing to map between the new and merged constant pools
1878
1879 // Copy attributes from scratch_cp to merge_cp
1880 merge_cp->copy_fields(scratch_cp());
1881
1882 if (old_cp->length() == scratch_cp->length()) {
1883 // The old and new constant pools are the same length and the
1884 // index map is empty. This means that the three constant pools
1885 // are equivalent (but not the same). Unfortunately, the new
1886 // constant pool has not gone through link resolution nor have
1887 // the new class bytecodes gone through constant pool cache
1888 // rewriting so we can't use the old constant pool with the new
1889 // class.
1890
1891 // toss the merged constant pool at return
1892 } else if (old_cp->length() < scratch_cp->length()) {
1893 // The old constant pool has fewer entries than the new constant
1894 // pool and the index map is empty. This means the new constant
1895 // pool is a superset of the old constant pool. However, the old
1896 // class bytecodes have already gone through constant pool cache
1897 // rewriting so we can't use the new constant pool with the old
1898 // class.
1899
1900 // toss the merged constant pool at return
1901 } else {
1902 // The old constant pool has more entries than the new constant
1903 // pool and the index map is empty. This means that both the old
1904 // and merged constant pools are supersets of the new constant
1905 // pool.
1906
1907 // Replace the new constant pool with a shrunken copy of the
1908 // merged constant pool
1909 set_new_constant_pool(loader_data, scratch_class, merge_cp, merge_cp_length,
1910 CHECK_(JVMTI_ERROR_OUT_OF_MEMORY));
1911 // The new constant pool replaces scratch_cp so have cleaner clean it up.
1912 // It can't be cleaned up while there are handles to it.
1913 cp_cleaner.add_scratch_cp(scratch_cp());
1914 }
1915 } else {
1916 if (log_is_enabled(Trace, redefine, class, constantpool)) {
1917 // don't want to loop unless we are tracing
1918 int count = 0;
1919 for (int i = 1; i < _index_map_p->length(); i++) {
1920 int value = _index_map_p->at(i);
1921
1922 if (value != -1) {
1923 log_trace(redefine, class, constantpool)("index_map[%d]: old=%d new=%d", count, i, value);
1924 count++;
1925 }
1926 }
1927 }
1928
1929 // We have entries mapped between the new and merged constant pools
1930 // so we have to rewrite some constant pool references.
1931 if (!rewrite_cp_refs(scratch_class)) {
1932 return JVMTI_ERROR_INTERNAL;
1933 }
1934
1935 // Copy attributes from scratch_cp to merge_cp (should be done after rewrite_cp_refs())
1936 merge_cp->copy_fields(scratch_cp());
1937
1938 // Replace the new constant pool with a shrunken copy of the
1939 // merged constant pool so now the rewritten bytecodes have
1940 // valid references; the previous new constant pool will get
1941 // GCed.
1942 set_new_constant_pool(loader_data, scratch_class, merge_cp, merge_cp_length,
1943 CHECK_(JVMTI_ERROR_OUT_OF_MEMORY));
1944 // The new constant pool replaces scratch_cp so have cleaner clean it up.
1945 // It can't be cleaned up while there are handles to it.
1946 cp_cleaner.add_scratch_cp(scratch_cp());
1947 }
1948
1949 return JVMTI_ERROR_NONE;
1950 } // end merge_cp_and_rewrite()
1951
1952
1953 // Rewrite constant pool references in klass scratch_class.
1954 bool VM_RedefineClasses::rewrite_cp_refs(InstanceKlass* scratch_class) {
1955
1956 // rewrite constant pool references in the nest attributes:
1957 if (!rewrite_cp_refs_in_nest_attributes(scratch_class)) {
1958 // propagate failure back to caller
1959 return false;
1960 }
1961
1962 // rewrite constant pool references in the Record attribute:
1963 if (!rewrite_cp_refs_in_record_attribute(scratch_class)) {
1964 // propagate failure back to caller
1965 return false;
1966 }
1967
1968 // rewrite constant pool references in the PermittedSubclasses attribute:
1969 if (!rewrite_cp_refs_in_permitted_subclasses_attribute(scratch_class)) {
1970 // propagate failure back to caller
1971 return false;
1972 }
1973
1974 // rewrite constant pool references in the methods:
1975 if (!rewrite_cp_refs_in_methods(scratch_class)) {
1976 // propagate failure back to caller
1977 return false;
1978 }
1979
1980 // rewrite constant pool references in the class_annotations:
1981 if (!rewrite_cp_refs_in_class_annotations(scratch_class)) {
1982 // propagate failure back to caller
1983 return false;
1984 }
1985
1986 // rewrite constant pool references in the fields_annotations:
1987 if (!rewrite_cp_refs_in_fields_annotations(scratch_class)) {
1988 // propagate failure back to caller
1989 return false;
1990 }
1991
1992 // rewrite constant pool references in the methods_annotations:
1993 if (!rewrite_cp_refs_in_methods_annotations(scratch_class)) {
1994 // propagate failure back to caller
1995 return false;
1996 }
1997
1998 // rewrite constant pool references in the methods_parameter_annotations:
1999 if (!rewrite_cp_refs_in_methods_parameter_annotations(scratch_class)) {
2000 // propagate failure back to caller
2001 return false;
2002 }
2003
2004 // rewrite constant pool references in the methods_default_annotations:
2005 if (!rewrite_cp_refs_in_methods_default_annotations(scratch_class)) {
2006 // propagate failure back to caller
2007 return false;
2008 }
2009
2010 // rewrite constant pool references in the class_type_annotations:
2011 if (!rewrite_cp_refs_in_class_type_annotations(scratch_class)) {
2012 // propagate failure back to caller
2013 return false;
2014 }
2015
2016 // rewrite constant pool references in the fields_type_annotations:
2017 if (!rewrite_cp_refs_in_fields_type_annotations(scratch_class)) {
2018 // propagate failure back to caller
2019 return false;
2020 }
2021
2022 // rewrite constant pool references in the methods_type_annotations:
2023 if (!rewrite_cp_refs_in_methods_type_annotations(scratch_class)) {
2024 // propagate failure back to caller
2025 return false;
2026 }
2027
2028 // There can be type annotations in the Code part of a method_info attribute.
2029 // These annotations are not accessible, even by reflection.
2030 // Currently they are not even parsed by the ClassFileParser.
2031 // If runtime access is added they will also need to be rewritten.
2032
2033 // rewrite source file name index:
2034 u2 source_file_name_idx = scratch_class->source_file_name_index();
2035 if (source_file_name_idx != 0) {
2036 u2 new_source_file_name_idx = find_new_index(source_file_name_idx);
2037 if (new_source_file_name_idx != 0) {
2038 scratch_class->set_source_file_name_index(new_source_file_name_idx);
2039 }
2040 }
2041
2042 // rewrite class generic signature index:
2043 u2 generic_signature_index = scratch_class->generic_signature_index();
2044 if (generic_signature_index != 0) {
2045 u2 new_generic_signature_index = find_new_index(generic_signature_index);
2046 if (new_generic_signature_index != 0) {
2047 scratch_class->set_generic_signature_index(new_generic_signature_index);
2048 }
2049 }
2050
2051 return true;
2052 } // end rewrite_cp_refs()
2053
2054 // Rewrite constant pool references in the NestHost and NestMembers attributes.
2055 bool VM_RedefineClasses::rewrite_cp_refs_in_nest_attributes(
2056 InstanceKlass* scratch_class) {
2057
2058 u2 cp_index = scratch_class->nest_host_index();
2059 if (cp_index != 0) {
2060 scratch_class->set_nest_host_index(find_new_index(cp_index));
2061 }
2062 Array<u2>* nest_members = scratch_class->nest_members();
2063 for (int i = 0; i < nest_members->length(); i++) {
2064 u2 cp_index = nest_members->at(i);
2065 nest_members->at_put(i, find_new_index(cp_index));
2066 }
2067 return true;
2068 }
2069
2070 // Rewrite constant pool references in the Record attribute.
2071 bool VM_RedefineClasses::rewrite_cp_refs_in_record_attribute(InstanceKlass* scratch_class) {
2072 Array<RecordComponent*>* components = scratch_class->record_components();
2073 if (components != nullptr) {
2074 for (int i = 0; i < components->length(); i++) {
2075 RecordComponent* component = components->at(i);
2076 u2 cp_index = component->name_index();
2077 component->set_name_index(find_new_index(cp_index));
2078 cp_index = component->descriptor_index();
2079 component->set_descriptor_index(find_new_index(cp_index));
2080 cp_index = component->generic_signature_index();
2081 if (cp_index != 0) {
2082 component->set_generic_signature_index(find_new_index(cp_index));
2083 }
2084
2085 AnnotationArray* annotations = component->annotations();
2086 if (annotations != nullptr && annotations->length() != 0) {
2087 int byte_i = 0; // byte index into annotations
2088 if (!rewrite_cp_refs_in_annotations_typeArray(annotations, byte_i)) {
2089 log_debug(redefine, class, annotation)("bad record_component_annotations at %d", i);
2090 // propagate failure back to caller
2091 return false;
2092 }
2093 }
2094
2095 AnnotationArray* type_annotations = component->type_annotations();
2096 if (type_annotations != nullptr && type_annotations->length() != 0) {
2097 int byte_i = 0; // byte index into annotations
2098 if (!rewrite_cp_refs_in_annotations_typeArray(type_annotations, byte_i)) {
2099 log_debug(redefine, class, annotation)("bad record_component_type_annotations at %d", i);
2100 // propagate failure back to caller
2101 return false;
2102 }
2103 }
2104 }
2105 }
2106 return true;
2107 }
2108
2109 // Rewrite constant pool references in the PermittedSubclasses attribute.
2110 bool VM_RedefineClasses::rewrite_cp_refs_in_permitted_subclasses_attribute(
2111 InstanceKlass* scratch_class) {
2112
2113 Array<u2>* permitted_subclasses = scratch_class->permitted_subclasses();
2114 assert(permitted_subclasses != nullptr, "unexpected null permitted_subclasses");
2115 for (int i = 0; i < permitted_subclasses->length(); i++) {
2116 u2 cp_index = permitted_subclasses->at(i);
2117 permitted_subclasses->at_put(i, find_new_index(cp_index));
2118 }
2119 return true;
2120 }
2121
2122 // Rewrite constant pool references in the methods.
2123 bool VM_RedefineClasses::rewrite_cp_refs_in_methods(InstanceKlass* scratch_class) {
2124
2125 Array<Method*>* methods = scratch_class->methods();
2126
2127 if (methods == nullptr || methods->length() == 0) {
2128 // no methods so nothing to do
2129 return true;
2130 }
2131
2132 JavaThread* THREAD = JavaThread::current(); // For exception macros.
2133 ExceptionMark em(THREAD);
2134
2135 // rewrite constant pool references in the methods:
2136 for (int i = methods->length() - 1; i >= 0; i--) {
2137 methodHandle method(THREAD, methods->at(i));
2138 methodHandle new_method;
2139 rewrite_cp_refs_in_method(method, &new_method, THREAD);
2140 if (!new_method.is_null()) {
2141 // the method has been replaced so save the new method version
2142 // even in the case of an exception. original method is on the
2143 // deallocation list.
2144 methods->at_put(i, new_method());
2145 }
2146 if (HAS_PENDING_EXCEPTION) {
2147 Symbol* ex_name = PENDING_EXCEPTION->klass()->name();
2148 log_info(redefine, class, load, exceptions)("rewrite_cp_refs_in_method exception: '%s'", ex_name->as_C_string());
2149 // Need to clear pending exception here as the super caller sets
2150 // the JVMTI_ERROR_INTERNAL if the returned value is false.
2151 CLEAR_PENDING_EXCEPTION;
2152 return false;
2153 }
2154 }
2155
2156 return true;
2157 }
2158
2159
2160 // Rewrite constant pool references in the specific method. This code
2161 // was adapted from Rewriter::rewrite_method().
2162 void VM_RedefineClasses::rewrite_cp_refs_in_method(methodHandle method,
2163 methodHandle *new_method_p, TRAPS) {
2164
2165 *new_method_p = methodHandle(); // default is no new method
2166
2167 // We cache a pointer to the bytecodes here in code_base. If GC
2168 // moves the Method*, then the bytecodes will also move which
2169 // will likely cause a crash. We create a NoSafepointVerifier
2170 // object to detect whether we pass a possible safepoint in this
2171 // code block.
2172 NoSafepointVerifier nsv;
2173
2174 // Bytecodes and their length
2175 address code_base = method->code_base();
2176 int code_length = method->code_size();
2177
2178 int bc_length;
2179 for (int bci = 0; bci < code_length; bci += bc_length) {
2180 address bcp = code_base + bci;
2181 Bytecodes::Code c = (Bytecodes::Code)(*bcp);
2182
2183 bc_length = Bytecodes::length_for(c);
2184 if (bc_length == 0) {
2185 // More complicated bytecodes report a length of zero so
2186 // we have to try again a slightly different way.
2187 bc_length = Bytecodes::length_at(method(), bcp);
2188 }
2189
2190 assert(bc_length != 0, "impossible bytecode length");
2191
2192 switch (c) {
2193 case Bytecodes::_ldc:
2194 {
2195 u1 cp_index = *(bcp + 1);
2196 u2 new_index = find_new_index(cp_index);
2197
2198 if (StressLdcRewrite && new_index == 0) {
2199 // If we are stressing ldc -> ldc_w rewriting, then we
2200 // always need a new_index value.
2201 new_index = cp_index;
2202 }
2203 if (new_index != 0) {
2204 // the original index is mapped so we have more work to do
2205 if (!StressLdcRewrite && new_index <= max_jubyte) {
2206 // The new value can still use ldc instead of ldc_w
2207 // unless we are trying to stress ldc -> ldc_w rewriting
2208 log_trace(redefine, class, constantpool)
2209 ("%s@" INTPTR_FORMAT " old=%d, new=%d", Bytecodes::name(c), p2i(bcp), cp_index, new_index);
2210 // We checked that new_index fits in a u1 so this cast is safe
2211 *(bcp + 1) = (u1)new_index;
2212 } else {
2213 log_trace(redefine, class, constantpool)
2214 ("%s->ldc_w@" INTPTR_FORMAT " old=%d, new=%d", Bytecodes::name(c), p2i(bcp), cp_index, new_index);
2215 // the new value needs ldc_w instead of ldc
2216 u_char inst_buffer[4]; // max instruction size is 4 bytes
2217 bcp = (address)inst_buffer;
2218 // construct new instruction sequence
2219 *bcp = Bytecodes::_ldc_w;
2220 bcp++;
2221 // Rewriter::rewrite_method() does not rewrite ldc -> ldc_w.
2222 // See comment below for difference between put_Java_u2()
2223 // and put_native_u2().
2224 Bytes::put_Java_u2(bcp, new_index);
2225
2226 Relocator rc(method, nullptr /* no RelocatorListener needed */);
2227 methodHandle m;
2228 {
2229 PauseNoSafepointVerifier pnsv(&nsv);
2230
2231 // ldc is 2 bytes and ldc_w is 3 bytes
2232 m = rc.insert_space_at(bci, 3, inst_buffer, CHECK);
2233 }
2234
2235 // return the new method so that the caller can update
2236 // the containing class
2237 *new_method_p = method = m;
2238 // switch our bytecode processing loop from the old method
2239 // to the new method
2240 code_base = method->code_base();
2241 code_length = method->code_size();
2242 bcp = code_base + bci;
2243 c = (Bytecodes::Code)(*bcp);
2244 bc_length = Bytecodes::length_for(c);
2245 assert(bc_length != 0, "sanity check");
2246 } // end we need ldc_w instead of ldc
2247 } // end if there is a mapped index
2248 } break;
2249
2250 // these bytecodes have a two-byte constant pool index
2251 case Bytecodes::_anewarray : // fall through
2252 case Bytecodes::_checkcast : // fall through
2253 case Bytecodes::_getfield : // fall through
2254 case Bytecodes::_getstatic : // fall through
2255 case Bytecodes::_instanceof : // fall through
2256 case Bytecodes::_invokedynamic : // fall through
2257 case Bytecodes::_invokeinterface: // fall through
2258 case Bytecodes::_invokespecial : // fall through
2259 case Bytecodes::_invokestatic : // fall through
2260 case Bytecodes::_invokevirtual : // fall through
2261 case Bytecodes::_ldc_w : // fall through
2262 case Bytecodes::_ldc2_w : // fall through
2263 case Bytecodes::_multianewarray : // fall through
2264 case Bytecodes::_new : // fall through
2265 case Bytecodes::_putfield : // fall through
2266 case Bytecodes::_putstatic :
2267 {
2268 address p = bcp + 1;
2269 int cp_index = Bytes::get_Java_u2(p);
2270 u2 new_index = find_new_index(cp_index);
2271 if (new_index != 0) {
2272 // the original index is mapped so update w/ new value
2273 log_trace(redefine, class, constantpool)
2274 ("%s@" INTPTR_FORMAT " old=%d, new=%d", Bytecodes::name(c),p2i(bcp), cp_index, new_index);
2275 // Rewriter::rewrite_method() uses put_native_u2() in this
2276 // situation because it is reusing the constant pool index
2277 // location for a native index into the ConstantPoolCache.
2278 // Since we are updating the constant pool index prior to
2279 // verification and ConstantPoolCache initialization, we
2280 // need to keep the new index in Java byte order.
2281 Bytes::put_Java_u2(p, new_index);
2282 }
2283 } break;
2284 default:
2285 break;
2286 }
2287 } // end for each bytecode
2288 } // end rewrite_cp_refs_in_method()
2289
2290
2291 // Rewrite constant pool references in the class_annotations field.
2292 bool VM_RedefineClasses::rewrite_cp_refs_in_class_annotations(InstanceKlass* scratch_class) {
2293
2294 AnnotationArray* class_annotations = scratch_class->class_annotations();
2295 if (class_annotations == nullptr || class_annotations->length() == 0) {
2296 // no class_annotations so nothing to do
2297 return true;
2298 }
2299
2300 log_debug(redefine, class, annotation)("class_annotations length=%d", class_annotations->length());
2301
2302 int byte_i = 0; // byte index into class_annotations
2303 return rewrite_cp_refs_in_annotations_typeArray(class_annotations, byte_i);
2304 }
2305
2306
2307 // Rewrite constant pool references in an annotations typeArray. This
2308 // "structure" is adapted from the RuntimeVisibleAnnotations_attribute
2309 // that is described in section 4.8.15 of the 2nd-edition of the VM spec:
2310 //
2311 // annotations_typeArray {
2312 // u2 num_annotations;
2313 // annotation annotations[num_annotations];
2314 // }
2315 //
2316 bool VM_RedefineClasses::rewrite_cp_refs_in_annotations_typeArray(
2317 AnnotationArray* annotations_typeArray, int &byte_i_ref) {
2318
2319 if ((byte_i_ref + 2) > annotations_typeArray->length()) {
2320 // not enough room for num_annotations field
2321 log_debug(redefine, class, annotation)("length() is too small for num_annotations field");
2322 return false;
2323 }
2324
2325 u2 num_annotations = Bytes::get_Java_u2((address)
2326 annotations_typeArray->adr_at(byte_i_ref));
2327 byte_i_ref += 2;
2328
2329 log_debug(redefine, class, annotation)("num_annotations=%d", num_annotations);
2330
2331 int calc_num_annotations = 0;
2332 for (; calc_num_annotations < num_annotations; calc_num_annotations++) {
2333 if (!rewrite_cp_refs_in_annotation_struct(annotations_typeArray, byte_i_ref)) {
2334 log_debug(redefine, class, annotation)("bad annotation_struct at %d", calc_num_annotations);
2335 // propagate failure back to caller
2336 return false;
2337 }
2338 }
2339 assert(num_annotations == calc_num_annotations, "sanity check");
2340
2341 return true;
2342 } // end rewrite_cp_refs_in_annotations_typeArray()
2343
2344
2345 // Rewrite constant pool references in the annotation struct portion of
2346 // an annotations_typeArray. This "structure" is from section 4.8.15 of
2347 // the 2nd-edition of the VM spec:
2348 //
2349 // struct annotation {
2350 // u2 type_index;
2351 // u2 num_element_value_pairs;
2352 // {
2353 // u2 element_name_index;
2354 // element_value value;
2355 // } element_value_pairs[num_element_value_pairs];
2356 // }
2357 //
2358 bool VM_RedefineClasses::rewrite_cp_refs_in_annotation_struct(
2359 AnnotationArray* annotations_typeArray, int &byte_i_ref) {
2360 if ((byte_i_ref + 2 + 2) > annotations_typeArray->length()) {
2361 // not enough room for smallest annotation_struct
2362 log_debug(redefine, class, annotation)("length() is too small for annotation_struct");
2363 return false;
2364 }
2365
2366 u2 type_index = rewrite_cp_ref_in_annotation_data(annotations_typeArray,
2367 byte_i_ref, "type_index");
2368
2369 u2 num_element_value_pairs = Bytes::get_Java_u2((address)
2370 annotations_typeArray->adr_at(byte_i_ref));
2371 byte_i_ref += 2;
2372
2373 log_debug(redefine, class, annotation)
2374 ("type_index=%d num_element_value_pairs=%d", type_index, num_element_value_pairs);
2375
2376 int calc_num_element_value_pairs = 0;
2377 for (; calc_num_element_value_pairs < num_element_value_pairs;
2378 calc_num_element_value_pairs++) {
2379 if ((byte_i_ref + 2) > annotations_typeArray->length()) {
2380 // not enough room for another element_name_index, let alone
2381 // the rest of another component
2382 log_debug(redefine, class, annotation)("length() is too small for element_name_index");
2383 return false;
2384 }
2385
2386 u2 element_name_index = rewrite_cp_ref_in_annotation_data(
2387 annotations_typeArray, byte_i_ref,
2388 "element_name_index");
2389
2390 log_debug(redefine, class, annotation)("element_name_index=%d", element_name_index);
2391
2392 if (!rewrite_cp_refs_in_element_value(annotations_typeArray, byte_i_ref)) {
2393 log_debug(redefine, class, annotation)("bad element_value at %d", calc_num_element_value_pairs);
2394 // propagate failure back to caller
2395 return false;
2396 }
2397 } // end for each component
2398 assert(num_element_value_pairs == calc_num_element_value_pairs,
2399 "sanity check");
2400
2401 return true;
2402 } // end rewrite_cp_refs_in_annotation_struct()
2403
2404
2405 // Rewrite a constant pool reference at the current position in
2406 // annotations_typeArray if needed. Returns the original constant
2407 // pool reference if a rewrite was not needed or the new constant
2408 // pool reference if a rewrite was needed.
2409 u2 VM_RedefineClasses::rewrite_cp_ref_in_annotation_data(
2410 AnnotationArray* annotations_typeArray, int &byte_i_ref,
2411 const char * trace_mesg) {
2412
2413 address cp_index_addr = (address)
2414 annotations_typeArray->adr_at(byte_i_ref);
2415 u2 old_cp_index = Bytes::get_Java_u2(cp_index_addr);
2416 u2 new_cp_index = find_new_index(old_cp_index);
2417 if (new_cp_index != 0) {
2418 log_debug(redefine, class, annotation)("mapped old %s=%d", trace_mesg, old_cp_index);
2419 Bytes::put_Java_u2(cp_index_addr, new_cp_index);
2420 old_cp_index = new_cp_index;
2421 }
2422 byte_i_ref += 2;
2423 return old_cp_index;
2424 }
2425
2426
2427 // Rewrite constant pool references in the element_value portion of an
2428 // annotations_typeArray. This "structure" is from section 4.8.15.1 of
2429 // the 2nd-edition of the VM spec:
2430 //
2431 // struct element_value {
2432 // u1 tag;
2433 // union {
2434 // u2 const_value_index;
2435 // {
2436 // u2 type_name_index;
2437 // u2 const_name_index;
2438 // } enum_const_value;
2439 // u2 class_info_index;
2440 // annotation annotation_value;
2441 // struct {
2442 // u2 num_values;
2443 // element_value values[num_values];
2444 // } array_value;
2445 // } value;
2446 // }
2447 //
2448 bool VM_RedefineClasses::rewrite_cp_refs_in_element_value(
2449 AnnotationArray* annotations_typeArray, int &byte_i_ref) {
2450
2451 if ((byte_i_ref + 1) > annotations_typeArray->length()) {
2452 // not enough room for a tag let alone the rest of an element_value
2453 log_debug(redefine, class, annotation)("length() is too small for a tag");
2454 return false;
2455 }
2456
2457 u1 tag = annotations_typeArray->at(byte_i_ref);
2458 byte_i_ref++;
2459 log_debug(redefine, class, annotation)("tag='%c'", tag);
2460
2461 switch (tag) {
2462 // These BaseType tag values are from Table 4.2 in VM spec:
2463 case JVM_SIGNATURE_BYTE:
2464 case JVM_SIGNATURE_CHAR:
2465 case JVM_SIGNATURE_DOUBLE:
2466 case JVM_SIGNATURE_FLOAT:
2467 case JVM_SIGNATURE_INT:
2468 case JVM_SIGNATURE_LONG:
2469 case JVM_SIGNATURE_SHORT:
2470 case JVM_SIGNATURE_BOOLEAN:
2471
2472 // The remaining tag values are from Table 4.8 in the 2nd-edition of
2473 // the VM spec:
2474 case 's':
2475 {
2476 // For the above tag values (including the BaseType values),
2477 // value.const_value_index is right union field.
2478
2479 if ((byte_i_ref + 2) > annotations_typeArray->length()) {
2480 // not enough room for a const_value_index
2481 log_debug(redefine, class, annotation)("length() is too small for a const_value_index");
2482 return false;
2483 }
2484
2485 u2 const_value_index = rewrite_cp_ref_in_annotation_data(
2486 annotations_typeArray, byte_i_ref,
2487 "const_value_index");
2488
2489 log_debug(redefine, class, annotation)("const_value_index=%d", const_value_index);
2490 } break;
2491
2492 case 'e':
2493 {
2494 // for the above tag value, value.enum_const_value is right union field
2495
2496 if ((byte_i_ref + 4) > annotations_typeArray->length()) {
2497 // not enough room for a enum_const_value
2498 log_debug(redefine, class, annotation)("length() is too small for a enum_const_value");
2499 return false;
2500 }
2501
2502 u2 type_name_index = rewrite_cp_ref_in_annotation_data(
2503 annotations_typeArray, byte_i_ref,
2504 "type_name_index");
2505
2506 u2 const_name_index = rewrite_cp_ref_in_annotation_data(
2507 annotations_typeArray, byte_i_ref,
2508 "const_name_index");
2509
2510 log_debug(redefine, class, annotation)
2511 ("type_name_index=%d const_name_index=%d", type_name_index, const_name_index);
2512 } break;
2513
2514 case 'c':
2515 {
2516 // for the above tag value, value.class_info_index is right union field
2517
2518 if ((byte_i_ref + 2) > annotations_typeArray->length()) {
2519 // not enough room for a class_info_index
2520 log_debug(redefine, class, annotation)("length() is too small for a class_info_index");
2521 return false;
2522 }
2523
2524 u2 class_info_index = rewrite_cp_ref_in_annotation_data(
2525 annotations_typeArray, byte_i_ref,
2526 "class_info_index");
2527
2528 log_debug(redefine, class, annotation)("class_info_index=%d", class_info_index);
2529 } break;
2530
2531 case '@':
2532 // For the above tag value, value.attr_value is the right union
2533 // field. This is a nested annotation.
2534 if (!rewrite_cp_refs_in_annotation_struct(annotations_typeArray, byte_i_ref)) {
2535 // propagate failure back to caller
2536 return false;
2537 }
2538 break;
2539
2540 case JVM_SIGNATURE_ARRAY:
2541 {
2542 if ((byte_i_ref + 2) > annotations_typeArray->length()) {
2543 // not enough room for a num_values field
2544 log_debug(redefine, class, annotation)("length() is too small for a num_values field");
2545 return false;
2546 }
2547
2548 // For the above tag value, value.array_value is the right union
2549 // field. This is an array of nested element_value.
2550 u2 num_values = Bytes::get_Java_u2((address)
2551 annotations_typeArray->adr_at(byte_i_ref));
2552 byte_i_ref += 2;
2553 log_debug(redefine, class, annotation)("num_values=%d", num_values);
2554
2555 int calc_num_values = 0;
2556 for (; calc_num_values < num_values; calc_num_values++) {
2557 if (!rewrite_cp_refs_in_element_value(annotations_typeArray, byte_i_ref)) {
2558 log_debug(redefine, class, annotation)("bad nested element_value at %d", calc_num_values);
2559 // propagate failure back to caller
2560 return false;
2561 }
2562 }
2563 assert(num_values == calc_num_values, "sanity check");
2564 } break;
2565
2566 default:
2567 log_debug(redefine, class, annotation)("bad tag=0x%x", tag);
2568 return false;
2569 } // end decode tag field
2570
2571 return true;
2572 } // end rewrite_cp_refs_in_element_value()
2573
2574
2575 // Rewrite constant pool references in a fields_annotations field.
2576 bool VM_RedefineClasses::rewrite_cp_refs_in_fields_annotations(
2577 InstanceKlass* scratch_class) {
2578
2579 Array<AnnotationArray*>* fields_annotations = scratch_class->fields_annotations();
2580
2581 if (fields_annotations == nullptr || fields_annotations->length() == 0) {
2582 // no fields_annotations so nothing to do
2583 return true;
2584 }
2585
2586 log_debug(redefine, class, annotation)("fields_annotations length=%d", fields_annotations->length());
2587
2588 for (int i = 0; i < fields_annotations->length(); i++) {
2589 AnnotationArray* field_annotations = fields_annotations->at(i);
2590 if (field_annotations == nullptr || field_annotations->length() == 0) {
2591 // this field does not have any annotations so skip it
2592 continue;
2593 }
2594
2595 int byte_i = 0; // byte index into field_annotations
2596 if (!rewrite_cp_refs_in_annotations_typeArray(field_annotations, byte_i)) {
2597 log_debug(redefine, class, annotation)("bad field_annotations at %d", i);
2598 // propagate failure back to caller
2599 return false;
2600 }
2601 }
2602
2603 return true;
2604 } // end rewrite_cp_refs_in_fields_annotations()
2605
2606
2607 // Rewrite constant pool references in a methods_annotations field.
2608 bool VM_RedefineClasses::rewrite_cp_refs_in_methods_annotations(
2609 InstanceKlass* scratch_class) {
2610
2611 for (int i = 0; i < scratch_class->methods()->length(); i++) {
2612 Method* m = scratch_class->methods()->at(i);
2613 AnnotationArray* method_annotations = m->constMethod()->method_annotations();
2614
2615 if (method_annotations == nullptr || method_annotations->length() == 0) {
2616 // this method does not have any annotations so skip it
2617 continue;
2618 }
2619
2620 int byte_i = 0; // byte index into method_annotations
2621 if (!rewrite_cp_refs_in_annotations_typeArray(method_annotations, byte_i)) {
2622 log_debug(redefine, class, annotation)("bad method_annotations at %d", i);
2623 // propagate failure back to caller
2624 return false;
2625 }
2626 }
2627
2628 return true;
2629 } // end rewrite_cp_refs_in_methods_annotations()
2630
2631
2632 // Rewrite constant pool references in a methods_parameter_annotations
2633 // field. This "structure" is adapted from the
2634 // RuntimeVisibleParameterAnnotations_attribute described in section
2635 // 4.8.17 of the 2nd-edition of the VM spec:
2636 //
2637 // methods_parameter_annotations_typeArray {
2638 // u1 num_parameters;
2639 // {
2640 // u2 num_annotations;
2641 // annotation annotations[num_annotations];
2642 // } parameter_annotations[num_parameters];
2643 // }
2644 //
2645 bool VM_RedefineClasses::rewrite_cp_refs_in_methods_parameter_annotations(
2646 InstanceKlass* scratch_class) {
2647
2648 for (int i = 0; i < scratch_class->methods()->length(); i++) {
2649 Method* m = scratch_class->methods()->at(i);
2650 AnnotationArray* method_parameter_annotations = m->constMethod()->parameter_annotations();
2651 if (method_parameter_annotations == nullptr
2652 || method_parameter_annotations->length() == 0) {
2653 // this method does not have any parameter annotations so skip it
2654 continue;
2655 }
2656
2657 if (method_parameter_annotations->length() < 1) {
2658 // not enough room for a num_parameters field
2659 log_debug(redefine, class, annotation)("length() is too small for a num_parameters field at %d", i);
2660 return false;
2661 }
2662
2663 int byte_i = 0; // byte index into method_parameter_annotations
2664
2665 u1 num_parameters = method_parameter_annotations->at(byte_i);
2666 byte_i++;
2667
2668 log_debug(redefine, class, annotation)("num_parameters=%d", num_parameters);
2669
2670 int calc_num_parameters = 0;
2671 for (; calc_num_parameters < num_parameters; calc_num_parameters++) {
2672 if (!rewrite_cp_refs_in_annotations_typeArray(method_parameter_annotations, byte_i)) {
2673 log_debug(redefine, class, annotation)("bad method_parameter_annotations at %d", calc_num_parameters);
2674 // propagate failure back to caller
2675 return false;
2676 }
2677 }
2678 assert(num_parameters == calc_num_parameters, "sanity check");
2679 }
2680
2681 return true;
2682 } // end rewrite_cp_refs_in_methods_parameter_annotations()
2683
2684
2685 // Rewrite constant pool references in a methods_default_annotations
2686 // field. This "structure" is adapted from the AnnotationDefault_attribute
2687 // that is described in section 4.8.19 of the 2nd-edition of the VM spec:
2688 //
2689 // methods_default_annotations_typeArray {
2690 // element_value default_value;
2691 // }
2692 //
2693 bool VM_RedefineClasses::rewrite_cp_refs_in_methods_default_annotations(
2694 InstanceKlass* scratch_class) {
2695
2696 for (int i = 0; i < scratch_class->methods()->length(); i++) {
2697 Method* m = scratch_class->methods()->at(i);
2698 AnnotationArray* method_default_annotations = m->constMethod()->default_annotations();
2699 if (method_default_annotations == nullptr
2700 || method_default_annotations->length() == 0) {
2701 // this method does not have any default annotations so skip it
2702 continue;
2703 }
2704
2705 int byte_i = 0; // byte index into method_default_annotations
2706
2707 if (!rewrite_cp_refs_in_element_value(
2708 method_default_annotations, byte_i)) {
2709 log_debug(redefine, class, annotation)("bad default element_value at %d", i);
2710 // propagate failure back to caller
2711 return false;
2712 }
2713 }
2714
2715 return true;
2716 } // end rewrite_cp_refs_in_methods_default_annotations()
2717
2718
2719 // Rewrite constant pool references in a class_type_annotations field.
2720 bool VM_RedefineClasses::rewrite_cp_refs_in_class_type_annotations(
2721 InstanceKlass* scratch_class) {
2722
2723 AnnotationArray* class_type_annotations = scratch_class->class_type_annotations();
2724 if (class_type_annotations == nullptr || class_type_annotations->length() == 0) {
2725 // no class_type_annotations so nothing to do
2726 return true;
2727 }
2728
2729 log_debug(redefine, class, annotation)("class_type_annotations length=%d", class_type_annotations->length());
2730
2731 int byte_i = 0; // byte index into class_type_annotations
2732 return rewrite_cp_refs_in_type_annotations_typeArray(class_type_annotations,
2733 byte_i, "ClassFile");
2734 } // end rewrite_cp_refs_in_class_type_annotations()
2735
2736
2737 // Rewrite constant pool references in a fields_type_annotations field.
2738 bool VM_RedefineClasses::rewrite_cp_refs_in_fields_type_annotations(InstanceKlass* scratch_class) {
2739
2740 Array<AnnotationArray*>* fields_type_annotations = scratch_class->fields_type_annotations();
2741 if (fields_type_annotations == nullptr || fields_type_annotations->length() == 0) {
2742 // no fields_type_annotations so nothing to do
2743 return true;
2744 }
2745
2746 log_debug(redefine, class, annotation)("fields_type_annotations length=%d", fields_type_annotations->length());
2747
2748 for (int i = 0; i < fields_type_annotations->length(); i++) {
2749 AnnotationArray* field_type_annotations = fields_type_annotations->at(i);
2750 if (field_type_annotations == nullptr || field_type_annotations->length() == 0) {
2751 // this field does not have any annotations so skip it
2752 continue;
2753 }
2754
2755 int byte_i = 0; // byte index into field_type_annotations
2756 if (!rewrite_cp_refs_in_type_annotations_typeArray(field_type_annotations,
2757 byte_i, "field_info")) {
2758 log_debug(redefine, class, annotation)("bad field_type_annotations at %d", i);
2759 // propagate failure back to caller
2760 return false;
2761 }
2762 }
2763
2764 return true;
2765 } // end rewrite_cp_refs_in_fields_type_annotations()
2766
2767
2768 // Rewrite constant pool references in a methods_type_annotations field.
2769 bool VM_RedefineClasses::rewrite_cp_refs_in_methods_type_annotations(
2770 InstanceKlass* scratch_class) {
2771
2772 for (int i = 0; i < scratch_class->methods()->length(); i++) {
2773 Method* m = scratch_class->methods()->at(i);
2774 AnnotationArray* method_type_annotations = m->constMethod()->type_annotations();
2775
2776 if (method_type_annotations == nullptr || method_type_annotations->length() == 0) {
2777 // this method does not have any annotations so skip it
2778 continue;
2779 }
2780
2781 log_debug(redefine, class, annotation)("methods type_annotations length=%d", method_type_annotations->length());
2782
2783 int byte_i = 0; // byte index into method_type_annotations
2784 if (!rewrite_cp_refs_in_type_annotations_typeArray(method_type_annotations,
2785 byte_i, "method_info")) {
2786 log_debug(redefine, class, annotation)("bad method_type_annotations at %d", i);
2787 // propagate failure back to caller
2788 return false;
2789 }
2790 }
2791
2792 return true;
2793 } // end rewrite_cp_refs_in_methods_type_annotations()
2794
2795
2796 // Rewrite constant pool references in a type_annotations
2797 // field. This "structure" is adapted from the
2798 // RuntimeVisibleTypeAnnotations_attribute described in
2799 // section 4.7.20 of the Java SE 8 Edition of the VM spec:
2800 //
2801 // type_annotations_typeArray {
2802 // u2 num_annotations;
2803 // type_annotation annotations[num_annotations];
2804 // }
2805 //
2806 bool VM_RedefineClasses::rewrite_cp_refs_in_type_annotations_typeArray(
2807 AnnotationArray* type_annotations_typeArray, int &byte_i_ref,
2808 const char * location_mesg) {
2809
2810 if ((byte_i_ref + 2) > type_annotations_typeArray->length()) {
2811 // not enough room for num_annotations field
2812 log_debug(redefine, class, annotation)("length() is too small for num_annotations field");
2813 return false;
2814 }
2815
2816 u2 num_annotations = Bytes::get_Java_u2((address)
2817 type_annotations_typeArray->adr_at(byte_i_ref));
2818 byte_i_ref += 2;
2819
2820 log_debug(redefine, class, annotation)("num_type_annotations=%d", num_annotations);
2821
2822 int calc_num_annotations = 0;
2823 for (; calc_num_annotations < num_annotations; calc_num_annotations++) {
2824 if (!rewrite_cp_refs_in_type_annotation_struct(type_annotations_typeArray,
2825 byte_i_ref, location_mesg)) {
2826 log_debug(redefine, class, annotation)("bad type_annotation_struct at %d", calc_num_annotations);
2827 // propagate failure back to caller
2828 return false;
2829 }
2830 }
2831 assert(num_annotations == calc_num_annotations, "sanity check");
2832
2833 if (byte_i_ref != type_annotations_typeArray->length()) {
2834 log_debug(redefine, class, annotation)
2835 ("read wrong amount of bytes at end of processing type_annotations_typeArray (%d of %d bytes were read)",
2836 byte_i_ref, type_annotations_typeArray->length());
2837 return false;
2838 }
2839
2840 return true;
2841 } // end rewrite_cp_refs_in_type_annotations_typeArray()
2842
2843
2844 // Rewrite constant pool references in a type_annotation
2845 // field. This "structure" is adapted from the
2846 // RuntimeVisibleTypeAnnotations_attribute described in
2847 // section 4.7.20 of the Java SE 8 Edition of the VM spec:
2848 //
2849 // type_annotation {
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 // type_path target_path;
2864 // annotation anno;
2865 // }
2866 //
2867 bool VM_RedefineClasses::rewrite_cp_refs_in_type_annotation_struct(
2868 AnnotationArray* type_annotations_typeArray, int &byte_i_ref,
2869 const char * location_mesg) {
2870
2871 if (!skip_type_annotation_target(type_annotations_typeArray,
2872 byte_i_ref, location_mesg)) {
2873 return false;
2874 }
2875
2876 if (!skip_type_annotation_type_path(type_annotations_typeArray, byte_i_ref)) {
2877 return false;
2878 }
2879
2880 if (!rewrite_cp_refs_in_annotation_struct(type_annotations_typeArray, byte_i_ref)) {
2881 return false;
2882 }
2883
2884 return true;
2885 } // end rewrite_cp_refs_in_type_annotation_struct()
2886
2887
2888 // Read, verify and skip over the target_type and target_info part
2889 // so that rewriting can continue in the later parts of the struct.
2890 //
2891 // u1 target_type;
2892 // union {
2893 // type_parameter_target;
2894 // supertype_target;
2895 // type_parameter_bound_target;
2896 // empty_target;
2897 // method_formal_parameter_target;
2898 // throws_target;
2899 // localvar_target;
2900 // catch_target;
2901 // offset_target;
2902 // type_argument_target;
2903 // } target_info;
2904 //
2905 bool VM_RedefineClasses::skip_type_annotation_target(
2906 AnnotationArray* type_annotations_typeArray, int &byte_i_ref,
2907 const char * location_mesg) {
2908
2909 if ((byte_i_ref + 1) > type_annotations_typeArray->length()) {
2910 // not enough room for a target_type let alone the rest of a type_annotation
2911 log_debug(redefine, class, annotation)("length() is too small for a target_type");
2912 return false;
2913 }
2914
2915 u1 target_type = type_annotations_typeArray->at(byte_i_ref);
2916 byte_i_ref += 1;
2917 log_debug(redefine, class, annotation)("target_type=0x%.2x", target_type);
2918 log_debug(redefine, class, annotation)("location=%s", location_mesg);
2919
2920 // Skip over target_info
2921 switch (target_type) {
2922 case 0x00:
2923 // kind: type parameter declaration of generic class or interface
2924 // location: ClassFile
2925 case 0x01:
2926 // kind: type parameter declaration of generic method or constructor
2927 // location: method_info
2928
2929 {
2930 // struct:
2931 // type_parameter_target {
2932 // u1 type_parameter_index;
2933 // }
2934 //
2935 if ((byte_i_ref + 1) > type_annotations_typeArray->length()) {
2936 log_debug(redefine, class, annotation)("length() is too small for a type_parameter_target");
2937 return false;
2938 }
2939
2940 u1 type_parameter_index = type_annotations_typeArray->at(byte_i_ref);
2941 byte_i_ref += 1;
2942
2943 log_debug(redefine, class, annotation)("type_parameter_target: type_parameter_index=%d", type_parameter_index);
2944 } break;
2945
2946 case 0x10:
2947 // kind: type in extends clause of class or interface declaration
2948 // or in implements clause of interface declaration
2949 // location: ClassFile
2950
2951 {
2952 // struct:
2953 // supertype_target {
2954 // u2 supertype_index;
2955 // }
2956 //
2957 if ((byte_i_ref + 2) > type_annotations_typeArray->length()) {
2958 log_debug(redefine, class, annotation)("length() is too small for a supertype_target");
2959 return false;
2960 }
2961
2962 u2 supertype_index = Bytes::get_Java_u2((address)
2963 type_annotations_typeArray->adr_at(byte_i_ref));
2964 byte_i_ref += 2;
2965
2966 log_debug(redefine, class, annotation)("supertype_target: supertype_index=%d", supertype_index);
2967 } break;
2968
2969 case 0x11:
2970 // kind: type in bound of type parameter declaration of generic class or interface
2971 // location: ClassFile
2972 case 0x12:
2973 // kind: type in bound of type parameter declaration of generic method or constructor
2974 // location: method_info
2975
2976 {
2977 // struct:
2978 // type_parameter_bound_target {
2979 // u1 type_parameter_index;
2980 // u1 bound_index;
2981 // }
2982 //
2983 if ((byte_i_ref + 2) > type_annotations_typeArray->length()) {
2984 log_debug(redefine, class, annotation)("length() is too small for a type_parameter_bound_target");
2985 return false;
2986 }
2987
2988 u1 type_parameter_index = type_annotations_typeArray->at(byte_i_ref);
2989 byte_i_ref += 1;
2990 u1 bound_index = type_annotations_typeArray->at(byte_i_ref);
2991 byte_i_ref += 1;
2992
2993 log_debug(redefine, class, annotation)
2994 ("type_parameter_bound_target: type_parameter_index=%d, bound_index=%d", type_parameter_index, bound_index);
2995 } break;
2996
2997 case 0x13:
2998 // kind: type in field declaration
2999 // location: field_info
3000 case 0x14:
3001 // kind: return type of method, or type of newly constructed object
3002 // location: method_info
3003 case 0x15:
3004 // kind: receiver type of method or constructor
3005 // location: method_info
3006
3007 {
3008 // struct:
3009 // empty_target {
3010 // }
3011 //
3012 log_debug(redefine, class, annotation)("empty_target");
3013 } break;
3014
3015 case 0x16:
3016 // kind: type in formal parameter declaration of method, constructor, or lambda expression
3017 // location: method_info
3018
3019 {
3020 // struct:
3021 // formal_parameter_target {
3022 // u1 formal_parameter_index;
3023 // }
3024 //
3025 if ((byte_i_ref + 1) > type_annotations_typeArray->length()) {
3026 log_debug(redefine, class, annotation)("length() is too small for a formal_parameter_target");
3027 return false;
3028 }
3029
3030 u1 formal_parameter_index = type_annotations_typeArray->at(byte_i_ref);
3031 byte_i_ref += 1;
3032
3033 log_debug(redefine, class, annotation)
3034 ("formal_parameter_target: formal_parameter_index=%d", formal_parameter_index);
3035 } break;
3036
3037 case 0x17:
3038 // kind: type in throws clause of method or constructor
3039 // location: method_info
3040
3041 {
3042 // struct:
3043 // throws_target {
3044 // u2 throws_type_index
3045 // }
3046 //
3047 if ((byte_i_ref + 2) > type_annotations_typeArray->length()) {
3048 log_debug(redefine, class, annotation)("length() is too small for a throws_target");
3049 return false;
3050 }
3051
3052 u2 throws_type_index = Bytes::get_Java_u2((address)
3053 type_annotations_typeArray->adr_at(byte_i_ref));
3054 byte_i_ref += 2;
3055
3056 log_debug(redefine, class, annotation)("throws_target: throws_type_index=%d", throws_type_index);
3057 } break;
3058
3059 case 0x40:
3060 // kind: type in local variable declaration
3061 // location: Code
3062 case 0x41:
3063 // kind: type in resource variable declaration
3064 // location: Code
3065
3066 {
3067 // struct:
3068 // localvar_target {
3069 // u2 table_length;
3070 // struct {
3071 // u2 start_pc;
3072 // u2 length;
3073 // u2 index;
3074 // } table[table_length];
3075 // }
3076 //
3077 if ((byte_i_ref + 2) > type_annotations_typeArray->length()) {
3078 // not enough room for a table_length let alone the rest of a localvar_target
3079 log_debug(redefine, class, annotation)("length() is too small for a localvar_target table_length");
3080 return false;
3081 }
3082
3083 u2 table_length = Bytes::get_Java_u2((address)
3084 type_annotations_typeArray->adr_at(byte_i_ref));
3085 byte_i_ref += 2;
3086
3087 log_debug(redefine, class, annotation)("localvar_target: table_length=%d", table_length);
3088
3089 int table_struct_size = 2 + 2 + 2; // 3 u2 variables per table entry
3090 int table_size = table_length * table_struct_size;
3091
3092 if ((byte_i_ref + table_size) > type_annotations_typeArray->length()) {
3093 // not enough room for a table
3094 log_debug(redefine, class, annotation)("length() is too small for a table array of length %d", table_length);
3095 return false;
3096 }
3097
3098 // Skip over table
3099 byte_i_ref += table_size;
3100 } break;
3101
3102 case 0x42:
3103 // kind: type in exception parameter declaration
3104 // location: Code
3105
3106 {
3107 // struct:
3108 // catch_target {
3109 // u2 exception_table_index;
3110 // }
3111 //
3112 if ((byte_i_ref + 2) > type_annotations_typeArray->length()) {
3113 log_debug(redefine, class, annotation)("length() is too small for a catch_target");
3114 return false;
3115 }
3116
3117 u2 exception_table_index = Bytes::get_Java_u2((address)
3118 type_annotations_typeArray->adr_at(byte_i_ref));
3119 byte_i_ref += 2;
3120
3121 log_debug(redefine, class, annotation)("catch_target: exception_table_index=%d", exception_table_index);
3122 } break;
3123
3124 case 0x43:
3125 // kind: type in instanceof expression
3126 // location: Code
3127 case 0x44:
3128 // kind: type in new expression
3129 // location: Code
3130 case 0x45:
3131 // kind: type in method reference expression using ::new
3132 // location: Code
3133 case 0x46:
3134 // kind: type in method reference expression using ::Identifier
3135 // location: Code
3136
3137 {
3138 // struct:
3139 // offset_target {
3140 // u2 offset;
3141 // }
3142 //
3143 if ((byte_i_ref + 2) > type_annotations_typeArray->length()) {
3144 log_debug(redefine, class, annotation)("length() is too small for a offset_target");
3145 return false;
3146 }
3147
3148 u2 offset = Bytes::get_Java_u2((address)
3149 type_annotations_typeArray->adr_at(byte_i_ref));
3150 byte_i_ref += 2;
3151
3152 log_debug(redefine, class, annotation)("offset_target: offset=%d", offset);
3153 } break;
3154
3155 case 0x47:
3156 // kind: type in cast expression
3157 // location: Code
3158 case 0x48:
3159 // kind: type argument for generic constructor in new expression or
3160 // explicit constructor invocation statement
3161 // location: Code
3162 case 0x49:
3163 // kind: type argument for generic method in method invocation expression
3164 // location: Code
3165 case 0x4A:
3166 // kind: type argument for generic constructor in method reference expression using ::new
3167 // location: Code
3168 case 0x4B:
3169 // kind: type argument for generic method in method reference expression using ::Identifier
3170 // location: Code
3171
3172 {
3173 // struct:
3174 // type_argument_target {
3175 // u2 offset;
3176 // u1 type_argument_index;
3177 // }
3178 //
3179 if ((byte_i_ref + 3) > type_annotations_typeArray->length()) {
3180 log_debug(redefine, class, annotation)("length() is too small for a type_argument_target");
3181 return false;
3182 }
3183
3184 u2 offset = Bytes::get_Java_u2((address)
3185 type_annotations_typeArray->adr_at(byte_i_ref));
3186 byte_i_ref += 2;
3187 u1 type_argument_index = type_annotations_typeArray->at(byte_i_ref);
3188 byte_i_ref += 1;
3189
3190 log_debug(redefine, class, annotation)
3191 ("type_argument_target: offset=%d, type_argument_index=%d", offset, type_argument_index);
3192 } break;
3193
3194 default:
3195 log_debug(redefine, class, annotation)("unknown target_type");
3196 #ifdef ASSERT
3197 ShouldNotReachHere();
3198 #endif
3199 return false;
3200 }
3201
3202 return true;
3203 } // end skip_type_annotation_target()
3204
3205
3206 // Read, verify and skip over the type_path part so that rewriting
3207 // can continue in the later parts of the struct.
3208 //
3209 // type_path {
3210 // u1 path_length;
3211 // {
3212 // u1 type_path_kind;
3213 // u1 type_argument_index;
3214 // } path[path_length];
3215 // }
3216 //
3217 bool VM_RedefineClasses::skip_type_annotation_type_path(
3218 AnnotationArray* type_annotations_typeArray, int &byte_i_ref) {
3219
3220 if ((byte_i_ref + 1) > type_annotations_typeArray->length()) {
3221 // not enough room for a path_length let alone the rest of the type_path
3222 log_debug(redefine, class, annotation)("length() is too small for a type_path");
3223 return false;
3224 }
3225
3226 u1 path_length = type_annotations_typeArray->at(byte_i_ref);
3227 byte_i_ref += 1;
3228
3229 log_debug(redefine, class, annotation)("type_path: path_length=%d", path_length);
3230
3231 int calc_path_length = 0;
3232 for (; calc_path_length < path_length; calc_path_length++) {
3233 if ((byte_i_ref + 1 + 1) > type_annotations_typeArray->length()) {
3234 // not enough room for a path
3235 log_debug(redefine, class, annotation)
3236 ("length() is too small for path entry %d of %d", calc_path_length, path_length);
3237 return false;
3238 }
3239
3240 u1 type_path_kind = type_annotations_typeArray->at(byte_i_ref);
3241 byte_i_ref += 1;
3242 u1 type_argument_index = type_annotations_typeArray->at(byte_i_ref);
3243 byte_i_ref += 1;
3244
3245 log_debug(redefine, class, annotation)
3246 ("type_path: path[%d]: type_path_kind=%d, type_argument_index=%d",
3247 calc_path_length, type_path_kind, type_argument_index);
3248
3249 if (type_path_kind > 3 || (type_path_kind != 3 && type_argument_index != 0)) {
3250 // not enough room for a path
3251 log_debug(redefine, class, annotation)("inconsistent type_path values");
3252 return false;
3253 }
3254 }
3255 assert(path_length == calc_path_length, "sanity check");
3256
3257 return true;
3258 } // end skip_type_annotation_type_path()
3259
3260
3261 // Rewrite constant pool references in the method's stackmap table.
3262 // These "structures" are adapted from the StackMapTable_attribute that
3263 // is described in section 4.8.4 of the 6.0 version of the VM spec
3264 // (dated 2005.10.26):
3265 // file:///net/quincunx.sfbay/export/gbracha/ClassFile-Java6.pdf
3266 //
3267 // stack_map {
3268 // u2 number_of_entries;
3269 // stack_map_frame entries[number_of_entries];
3270 // }
3271 //
3272 void VM_RedefineClasses::rewrite_cp_refs_in_stack_map_table(
3273 const methodHandle& method) {
3274
3275 if (!method->has_stackmap_table()) {
3276 return;
3277 }
3278
3279 AnnotationArray* stackmap_data = method->stackmap_data();
3280 address stackmap_p = (address)stackmap_data->adr_at(0);
3281 address stackmap_end = stackmap_p + stackmap_data->length();
3282
3283 assert(stackmap_p + 2 <= stackmap_end, "no room for number_of_entries");
3284 u2 number_of_entries = Bytes::get_Java_u2(stackmap_p);
3285 stackmap_p += 2;
3286
3287 log_debug(redefine, class, stackmap)("number_of_entries=%u", number_of_entries);
3288
3289 // walk through each stack_map_frame
3290 u2 calc_number_of_entries = 0;
3291 for (; calc_number_of_entries < number_of_entries; calc_number_of_entries++) {
3292 // The stack_map_frame structure is a u1 frame_type followed by
3293 // 0 or more bytes of data:
3294 //
3295 // union stack_map_frame {
3296 // same_frame;
3297 // same_locals_1_stack_item_frame;
3298 // same_locals_1_stack_item_frame_extended;
3299 // chop_frame;
3300 // same_frame_extended;
3301 // append_frame;
3302 // full_frame;
3303 // }
3304
3305 assert(stackmap_p + 1 <= stackmap_end, "no room for frame_type");
3306 u1 frame_type = *stackmap_p;
3307 stackmap_p++;
3308
3309 // same_frame {
3310 // u1 frame_type = SAME; /* 0-63 */
3311 // }
3312 if (frame_type <= 63) {
3313 // nothing more to do for same_frame
3314 }
3315
3316 // same_locals_1_stack_item_frame {
3317 // u1 frame_type = SAME_LOCALS_1_STACK_ITEM; /* 64-127 */
3318 // verification_type_info stack[1];
3319 // }
3320 else if (frame_type >= 64 && frame_type <= 127) {
3321 rewrite_cp_refs_in_verification_type_info(stackmap_p, stackmap_end,
3322 calc_number_of_entries, frame_type);
3323 }
3324
3325 // reserved for future use
3326 else if (frame_type >= 128 && frame_type <= 246) {
3327 // nothing more to do for reserved frame_types
3328 }
3329
3330 // same_locals_1_stack_item_frame_extended {
3331 // u1 frame_type = SAME_LOCALS_1_STACK_ITEM_EXTENDED; /* 247 */
3332 // u2 offset_delta;
3333 // verification_type_info stack[1];
3334 // }
3335 else if (frame_type == 247) {
3336 stackmap_p += 2;
3337 rewrite_cp_refs_in_verification_type_info(stackmap_p, stackmap_end,
3338 calc_number_of_entries, frame_type);
3339 }
3340
3341 // chop_frame {
3342 // u1 frame_type = CHOP; /* 248-250 */
3343 // u2 offset_delta;
3344 // }
3345 else if (frame_type >= 248 && frame_type <= 250) {
3346 stackmap_p += 2;
3347 }
3348
3349 // same_frame_extended {
3350 // u1 frame_type = SAME_FRAME_EXTENDED; /* 251*/
3351 // u2 offset_delta;
3352 // }
3353 else if (frame_type == 251) {
3354 stackmap_p += 2;
3355 }
3356
3357 // append_frame {
3358 // u1 frame_type = APPEND; /* 252-254 */
3359 // u2 offset_delta;
3360 // verification_type_info locals[frame_type - 251];
3361 // }
3362 else if (frame_type >= 252 && frame_type <= 254) {
3363 assert(stackmap_p + 2 <= stackmap_end,
3364 "no room for offset_delta");
3365 stackmap_p += 2;
3366 u1 len = frame_type - 251;
3367 for (u1 i = 0; i < len; i++) {
3368 rewrite_cp_refs_in_verification_type_info(stackmap_p, stackmap_end,
3369 calc_number_of_entries, frame_type);
3370 }
3371 }
3372
3373 // full_frame {
3374 // u1 frame_type = FULL_FRAME; /* 255 */
3375 // u2 offset_delta;
3376 // u2 number_of_locals;
3377 // verification_type_info locals[number_of_locals];
3378 // u2 number_of_stack_items;
3379 // verification_type_info stack[number_of_stack_items];
3380 // }
3381 else if (frame_type == 255) {
3382 assert(stackmap_p + 2 + 2 <= stackmap_end,
3383 "no room for smallest full_frame");
3384 stackmap_p += 2;
3385
3386 u2 number_of_locals = Bytes::get_Java_u2(stackmap_p);
3387 stackmap_p += 2;
3388
3389 for (u2 locals_i = 0; locals_i < number_of_locals; locals_i++) {
3390 rewrite_cp_refs_in_verification_type_info(stackmap_p, stackmap_end,
3391 calc_number_of_entries, frame_type);
3392 }
3393
3394 // Use the largest size for the number_of_stack_items, but only get
3395 // the right number of bytes.
3396 u2 number_of_stack_items = Bytes::get_Java_u2(stackmap_p);
3397 stackmap_p += 2;
3398
3399 for (u2 stack_i = 0; stack_i < number_of_stack_items; stack_i++) {
3400 rewrite_cp_refs_in_verification_type_info(stackmap_p, stackmap_end,
3401 calc_number_of_entries, frame_type);
3402 }
3403 }
3404 } // end while there is a stack_map_frame
3405 assert(number_of_entries == calc_number_of_entries, "sanity check");
3406 } // end rewrite_cp_refs_in_stack_map_table()
3407
3408
3409 // Rewrite constant pool references in the verification type info
3410 // portion of the method's stackmap table. These "structures" are
3411 // adapted from the StackMapTable_attribute that is described in
3412 // section 4.8.4 of the 6.0 version of the VM spec (dated 2005.10.26):
3413 // file:///net/quincunx.sfbay/export/gbracha/ClassFile-Java6.pdf
3414 //
3415 // The verification_type_info structure is a u1 tag followed by 0 or
3416 // more bytes of data:
3417 //
3418 // union verification_type_info {
3419 // Top_variable_info;
3420 // Integer_variable_info;
3421 // Float_variable_info;
3422 // Long_variable_info;
3423 // Double_variable_info;
3424 // Null_variable_info;
3425 // UninitializedThis_variable_info;
3426 // Object_variable_info;
3427 // Uninitialized_variable_info;
3428 // }
3429 //
3430 void VM_RedefineClasses::rewrite_cp_refs_in_verification_type_info(
3431 address& stackmap_p_ref, address stackmap_end, u2 frame_i,
3432 u1 frame_type) {
3433
3434 assert(stackmap_p_ref + 1 <= stackmap_end, "no room for tag");
3435 u1 tag = *stackmap_p_ref;
3436 stackmap_p_ref++;
3437
3438 switch (tag) {
3439 // Top_variable_info {
3440 // u1 tag = ITEM_Top; /* 0 */
3441 // }
3442 // verificationType.hpp has zero as ITEM_Bogus instead of ITEM_Top
3443 case 0: // fall through
3444
3445 // Integer_variable_info {
3446 // u1 tag = ITEM_Integer; /* 1 */
3447 // }
3448 case ITEM_Integer: // fall through
3449
3450 // Float_variable_info {
3451 // u1 tag = ITEM_Float; /* 2 */
3452 // }
3453 case ITEM_Float: // fall through
3454
3455 // Double_variable_info {
3456 // u1 tag = ITEM_Double; /* 3 */
3457 // }
3458 case ITEM_Double: // fall through
3459
3460 // Long_variable_info {
3461 // u1 tag = ITEM_Long; /* 4 */
3462 // }
3463 case ITEM_Long: // fall through
3464
3465 // Null_variable_info {
3466 // u1 tag = ITEM_Null; /* 5 */
3467 // }
3468 case ITEM_Null: // fall through
3469
3470 // UninitializedThis_variable_info {
3471 // u1 tag = ITEM_UninitializedThis; /* 6 */
3472 // }
3473 case ITEM_UninitializedThis:
3474 // nothing more to do for the above tag types
3475 break;
3476
3477 // Object_variable_info {
3478 // u1 tag = ITEM_Object; /* 7 */
3479 // u2 cpool_index;
3480 // }
3481 case ITEM_Object:
3482 {
3483 assert(stackmap_p_ref + 2 <= stackmap_end, "no room for cpool_index");
3484 u2 cpool_index = Bytes::get_Java_u2(stackmap_p_ref);
3485 u2 new_cp_index = find_new_index(cpool_index);
3486 if (new_cp_index != 0) {
3487 log_debug(redefine, class, stackmap)("mapped old cpool_index=%d", cpool_index);
3488 Bytes::put_Java_u2(stackmap_p_ref, new_cp_index);
3489 cpool_index = new_cp_index;
3490 }
3491 stackmap_p_ref += 2;
3492
3493 log_debug(redefine, class, stackmap)
3494 ("frame_i=%u, frame_type=%u, cpool_index=%d", frame_i, frame_type, cpool_index);
3495 } break;
3496
3497 // Uninitialized_variable_info {
3498 // u1 tag = ITEM_Uninitialized; /* 8 */
3499 // u2 offset;
3500 // }
3501 case ITEM_Uninitialized:
3502 assert(stackmap_p_ref + 2 <= stackmap_end, "no room for offset");
3503 stackmap_p_ref += 2;
3504 break;
3505
3506 default:
3507 log_debug(redefine, class, stackmap)("frame_i=%u, frame_type=%u, bad tag=0x%x", frame_i, frame_type, tag);
3508 ShouldNotReachHere();
3509 break;
3510 } // end switch (tag)
3511 } // end rewrite_cp_refs_in_verification_type_info()
3512
3513
3514 // Change the constant pool associated with klass scratch_class to scratch_cp.
3515 // scratch_cp_length elements are copied from scratch_cp to a smaller constant pool
3516 // and the smaller constant pool is associated with scratch_class.
3517 void VM_RedefineClasses::set_new_constant_pool(
3518 ClassLoaderData* loader_data,
3519 InstanceKlass* scratch_class, constantPoolHandle scratch_cp,
3520 int scratch_cp_length, TRAPS) {
3521 assert(scratch_cp->length() >= scratch_cp_length, "sanity check");
3522
3523 // scratch_cp is a merged constant pool and has enough space for a
3524 // worst case merge situation. We want to associate the minimum
3525 // sized constant pool with the klass to save space.
3526 ConstantPool* cp = ConstantPool::allocate(loader_data, scratch_cp_length, CHECK);
3527 constantPoolHandle smaller_cp(THREAD, cp);
3528
3529 // preserve version() value in the smaller copy
3530 int version = scratch_cp->version();
3531 assert(version != 0, "sanity check");
3532 smaller_cp->set_version(version);
3533
3534 // attach klass to new constant pool
3535 // reference to the cp holder is needed for copy_operands()
3536 smaller_cp->set_pool_holder(scratch_class);
3537
3538 smaller_cp->copy_fields(scratch_cp());
3539
3540 scratch_cp->copy_cp_to(1, scratch_cp_length - 1, smaller_cp, 1, THREAD);
3541 if (HAS_PENDING_EXCEPTION) {
3542 // Exception is handled in the caller
3543 loader_data->add_to_deallocate_list(smaller_cp());
3544 return;
3545 }
3546 scratch_cp = smaller_cp;
3547
3548 // attach new constant pool to klass
3549 scratch_class->set_constants(scratch_cp());
3550 scratch_cp->initialize_unresolved_klasses(loader_data, CHECK);
3551
3552 int i; // for portability
3553
3554 // update each field in klass to use new constant pool indices as needed
3555 int java_fields;
3556 int injected_fields;
3557 bool update_required = false;
3558 GrowableArray<FieldInfo>* fields = FieldInfoStream::create_FieldInfoArray(scratch_class->fieldinfo_stream(), &java_fields, &injected_fields);
3559 for (int i = 0; i < java_fields; i++) {
3560 FieldInfo* fi = fields->adr_at(i);
3561 jshort cur_index = fi->name_index();
3562 jshort new_index = find_new_index(cur_index);
3563 if (new_index != 0) {
3564 log_trace(redefine, class, constantpool)("field-name_index change: %d to %d", cur_index, new_index);
3565 fi->set_name_index(new_index);
3566 update_required = true;
3567 }
3568 cur_index = fi->signature_index();
3569 new_index = find_new_index(cur_index);
3570 if (new_index != 0) {
3571 log_trace(redefine, class, constantpool)("field-signature_index change: %d to %d", cur_index, new_index);
3572 fi->set_signature_index(new_index);
3573 update_required = true;
3574 }
3575 cur_index = fi->initializer_index();
3576 new_index = find_new_index(cur_index);
3577 if (new_index != 0) {
3578 log_trace(redefine, class, constantpool)("field-initval_index change: %d to %d", cur_index, new_index);
3579 fi->set_initializer_index(new_index);
3580 update_required = true;
3581 }
3582 cur_index = fi->generic_signature_index();
3583 new_index = find_new_index(cur_index);
3584 if (new_index != 0) {
3585 log_trace(redefine, class, constantpool)("field-generic_signature change: %d to %d", cur_index, new_index);
3586 fi->set_generic_signature_index(new_index);
3587 update_required = true;
3588 }
3589 }
3590 if (update_required) {
3591 Array<u1>* old_stream = scratch_class->fieldinfo_stream();
3592 assert(fields->length() == (java_fields + injected_fields), "Must be");
3593 Array<u1>* new_fis = FieldInfoStream::create_FieldInfoStream(fields, java_fields, injected_fields, scratch_class->class_loader_data(), CHECK);
3594 scratch_class->set_fieldinfo_stream(new_fis);
3595 MetadataFactory::free_array<u1>(scratch_class->class_loader_data(), old_stream);
3596 }
3597
3598 // Update constant pool indices in the inner classes info to use
3599 // new constant indices as needed. The inner classes info is a
3600 // quadruple:
3601 // (inner_class_info, outer_class_info, inner_name, inner_access_flags)
3602 InnerClassesIterator iter(scratch_class);
3603 for (; !iter.done(); iter.next()) {
3604 int cur_index = iter.inner_class_info_index();
3605 if (cur_index == 0) {
3606 continue; // JVM spec. allows null inner class refs so skip it
3607 }
3608 u2 new_index = find_new_index(cur_index);
3609 if (new_index != 0) {
3610 log_trace(redefine, class, constantpool)("inner_class_info change: %d to %d", cur_index, new_index);
3611 iter.set_inner_class_info_index(new_index);
3612 }
3613 cur_index = iter.outer_class_info_index();
3614 new_index = find_new_index(cur_index);
3615 if (new_index != 0) {
3616 log_trace(redefine, class, constantpool)("outer_class_info change: %d to %d", cur_index, new_index);
3617 iter.set_outer_class_info_index(new_index);
3618 }
3619 cur_index = iter.inner_name_index();
3620 new_index = find_new_index(cur_index);
3621 if (new_index != 0) {
3622 log_trace(redefine, class, constantpool)("inner_name change: %d to %d", cur_index, new_index);
3623 iter.set_inner_name_index(new_index);
3624 }
3625 } // end for each inner class
3626
3627 // Attach each method in klass to the new constant pool and update
3628 // to use new constant pool indices as needed:
3629 Array<Method*>* methods = scratch_class->methods();
3630 for (i = methods->length() - 1; i >= 0; i--) {
3631 methodHandle method(THREAD, methods->at(i));
3632 method->set_constants(scratch_cp());
3633
3634 u2 new_index = find_new_index(method->name_index());
3635 if (new_index != 0) {
3636 log_trace(redefine, class, constantpool)
3637 ("method-name_index change: %d to %d", method->name_index(), new_index);
3638 method->set_name_index(new_index);
3639 }
3640 new_index = find_new_index(method->signature_index());
3641 if (new_index != 0) {
3642 log_trace(redefine, class, constantpool)
3643 ("method-signature_index change: %d to %d", method->signature_index(), new_index);
3644 method->set_signature_index(new_index);
3645 }
3646 new_index = find_new_index(method->generic_signature_index());
3647 if (new_index != 0) {
3648 log_trace(redefine, class, constantpool)
3649 ("method-generic_signature_index change: %d to %d", method->generic_signature_index(), new_index);
3650 method->constMethod()->set_generic_signature_index(new_index);
3651 }
3652
3653 // Update constant pool indices in the method's checked exception
3654 // table to use new constant indices as needed.
3655 int cext_length = method->checked_exceptions_length();
3656 if (cext_length > 0) {
3657 CheckedExceptionElement * cext_table =
3658 method->checked_exceptions_start();
3659 for (int j = 0; j < cext_length; j++) {
3660 int cur_index = cext_table[j].class_cp_index;
3661 int new_index = find_new_index(cur_index);
3662 if (new_index != 0) {
3663 log_trace(redefine, class, constantpool)("cext-class_cp_index change: %d to %d", cur_index, new_index);
3664 cext_table[j].class_cp_index = (u2)new_index;
3665 }
3666 } // end for each checked exception table entry
3667 } // end if there are checked exception table entries
3668
3669 // Update each catch type index in the method's exception table
3670 // to use new constant pool indices as needed. The exception table
3671 // holds quadruple entries of the form:
3672 // (beg_bci, end_bci, handler_bci, klass_index)
3673
3674 ExceptionTable ex_table(method());
3675 int ext_length = ex_table.length();
3676
3677 for (int j = 0; j < ext_length; j ++) {
3678 int cur_index = ex_table.catch_type_index(j);
3679 u2 new_index = find_new_index(cur_index);
3680 if (new_index != 0) {
3681 log_trace(redefine, class, constantpool)("ext-klass_index change: %d to %d", cur_index, new_index);
3682 ex_table.set_catch_type_index(j, new_index);
3683 }
3684 } // end for each exception table entry
3685
3686 // Update constant pool indices in the method's local variable
3687 // table to use new constant indices as needed. The local variable
3688 // table hold sextuple entries of the form:
3689 // (start_pc, length, name_index, descriptor_index, signature_index, slot)
3690 int lvt_length = method->localvariable_table_length();
3691 if (lvt_length > 0) {
3692 LocalVariableTableElement * lv_table =
3693 method->localvariable_table_start();
3694 for (int j = 0; j < lvt_length; j++) {
3695 int cur_index = lv_table[j].name_cp_index;
3696 int new_index = find_new_index(cur_index);
3697 if (new_index != 0) {
3698 log_trace(redefine, class, constantpool)("lvt-name_cp_index change: %d to %d", cur_index, new_index);
3699 lv_table[j].name_cp_index = (u2)new_index;
3700 }
3701 cur_index = lv_table[j].descriptor_cp_index;
3702 new_index = find_new_index(cur_index);
3703 if (new_index != 0) {
3704 log_trace(redefine, class, constantpool)("lvt-descriptor_cp_index change: %d to %d", cur_index, new_index);
3705 lv_table[j].descriptor_cp_index = (u2)new_index;
3706 }
3707 cur_index = lv_table[j].signature_cp_index;
3708 new_index = find_new_index(cur_index);
3709 if (new_index != 0) {
3710 log_trace(redefine, class, constantpool)("lvt-signature_cp_index change: %d to %d", cur_index, new_index);
3711 lv_table[j].signature_cp_index = (u2)new_index;
3712 }
3713 } // end for each local variable table entry
3714 } // end if there are local variable table entries
3715
3716 // Update constant pool indices in the method's method_parameters.
3717 int mp_length = method->method_parameters_length();
3718 if (mp_length > 0) {
3719 MethodParametersElement* elem = method->method_parameters_start();
3720 for (int j = 0; j < mp_length; j++) {
3721 const int cp_index = elem[j].name_cp_index;
3722 const int new_cp_index = find_new_index(cp_index);
3723 if (new_cp_index != 0) {
3724 elem[j].name_cp_index = (u2)new_cp_index;
3725 }
3726 }
3727 }
3728
3729 rewrite_cp_refs_in_stack_map_table(method);
3730 } // end for each method
3731 } // end set_new_constant_pool()
3732
3733
3734 // Unevolving classes may point to methods of the_class directly
3735 // from their constant pool caches, itables, and/or vtables. We
3736 // use the ClassLoaderDataGraph::classes_do() facility and this helper
3737 // to fix up these pointers. MethodData also points to old methods and
3738 // must be cleaned.
3739
3740 // Adjust cpools and vtables closure
3741 void VM_RedefineClasses::AdjustAndCleanMetadata::do_klass(Klass* k) {
3742
3743 // This is a very busy routine. We don't want too much tracing
3744 // printed out.
3745 bool trace_name_printed = false;
3746
3747 // If the class being redefined is java.lang.Object, we need to fix all
3748 // array class vtables also. The _has_redefined_Object flag is global.
3749 // Once the java.lang.Object has been redefined (by the current or one
3750 // of the previous VM_RedefineClasses operations) we have to always
3751 // adjust method entries for array classes.
3752 if (k->is_array_klass() && _has_redefined_Object) {
3753 k->vtable().adjust_method_entries(&trace_name_printed);
3754
3755 } else if (k->is_instance_klass()) {
3756 HandleMark hm(_thread);
3757 InstanceKlass *ik = InstanceKlass::cast(k);
3758
3759 // Clean MethodData of this class's methods so they don't refer to
3760 // old methods that are no longer running.
3761 Array<Method*>* methods = ik->methods();
3762 int num_methods = methods->length();
3763 for (int index = 0; index < num_methods; ++index) {
3764 if (methods->at(index)->method_data() != nullptr) {
3765 methods->at(index)->method_data()->clean_weak_method_links();
3766 }
3767 }
3768
3769 // Adjust all vtables, default methods and itables, to clean out old methods.
3770 ResourceMark rm(_thread);
3771 if (ik->vtable_length() > 0) {
3772 ik->vtable().adjust_method_entries(&trace_name_printed);
3773 ik->adjust_default_methods(&trace_name_printed);
3774 }
3775
3776 if (ik->itable_length() > 0) {
3777 ik->itable().adjust_method_entries(&trace_name_printed);
3778 }
3779
3780 // The constant pools in other classes (other_cp) can refer to
3781 // old methods. We have to update method information in
3782 // other_cp's cache. If other_cp has a previous version, then we
3783 // have to repeat the process for each previous version. The
3784 // constant pool cache holds the Method*s for non-virtual
3785 // methods and for virtual, final methods.
3786 //
3787 // Special case: if the current class is being redefined by the current
3788 // VM_RedefineClasses operation, then new_cp has already been attached
3789 // to the_class and old_cp has already been added as a previous version.
3790 // The new_cp doesn't have any cached references to old methods so it
3791 // doesn't need to be updated and we could optimize by skipping it.
3792 // However, the current class can be marked as being redefined by another
3793 // VM_RedefineClasses operation which has already executed its doit_prologue
3794 // and needs cpcache method entries adjusted. For simplicity, the cpcache
3795 // update is done unconditionally. It should result in doing nothing for
3796 // classes being redefined by the current VM_RedefineClasses operation.
3797 // Method entries in the previous version(s) are adjusted as well.
3798 ConstantPoolCache* cp_cache;
3799
3800 // this klass' constant pool cache may need adjustment
3801 ConstantPool* other_cp = ik->constants();
3802 cp_cache = other_cp->cache();
3803 if (cp_cache != nullptr) {
3804 cp_cache->adjust_method_entries(&trace_name_printed);
3805 }
3806
3807 // the previous versions' constant pool caches may need adjustment
3808 for (InstanceKlass* pv_node = ik->previous_versions();
3809 pv_node != nullptr;
3810 pv_node = pv_node->previous_versions()) {
3811 cp_cache = pv_node->constants()->cache();
3812 if (cp_cache != nullptr) {
3813 cp_cache->adjust_method_entries(&trace_name_printed);
3814 }
3815 }
3816 }
3817 }
3818
3819 void VM_RedefineClasses::update_jmethod_ids() {
3820 for (int j = 0; j < _matching_methods_length; ++j) {
3821 Method* old_method = _matching_old_methods[j];
3822 jmethodID jmid = old_method->find_jmethod_id_or_null();
3823 if (jmid != nullptr) {
3824 // There is a jmethodID, change it to point to the new method
3825 Method* new_method = _matching_new_methods[j];
3826 Method::change_method_associated_with_jmethod_id(jmid, new_method);
3827 assert(Method::resolve_jmethod_id(jmid) == _matching_new_methods[j],
3828 "should be replaced");
3829 }
3830 }
3831 }
3832
3833 int VM_RedefineClasses::check_methods_and_mark_as_obsolete() {
3834 int emcp_method_count = 0;
3835 int obsolete_count = 0;
3836 int old_index = 0;
3837 for (int j = 0; j < _matching_methods_length; ++j, ++old_index) {
3838 Method* old_method = _matching_old_methods[j];
3839 Method* new_method = _matching_new_methods[j];
3840 Method* old_array_method;
3841
3842 // Maintain an old_index into the _old_methods array by skipping
3843 // deleted methods
3844 while ((old_array_method = _old_methods->at(old_index)) != old_method) {
3845 ++old_index;
3846 }
3847
3848 if (MethodComparator::methods_EMCP(old_method, new_method)) {
3849 // The EMCP definition from JSR-163 requires the bytecodes to be
3850 // the same with the exception of constant pool indices which may
3851 // differ. However, the constants referred to by those indices
3852 // must be the same.
3853 //
3854 // We use methods_EMCP() for comparison since constant pool
3855 // merging can remove duplicate constant pool entries that were
3856 // present in the old method and removed from the rewritten new
3857 // method. A faster binary comparison function would consider the
3858 // old and new methods to be different when they are actually
3859 // EMCP.
3860 //
3861 // The old and new methods are EMCP and you would think that we
3862 // could get rid of one of them here and now and save some space.
3863 // However, the concept of EMCP only considers the bytecodes and
3864 // the constant pool entries in the comparison. Other things,
3865 // e.g., the line number table (LNT) or the local variable table
3866 // (LVT) don't count in the comparison. So the new (and EMCP)
3867 // method can have a new LNT that we need so we can't just
3868 // overwrite the new method with the old method.
3869 //
3870 // When this routine is called, we have already attached the new
3871 // methods to the_class so the old methods are effectively
3872 // overwritten. However, if an old method is still executing,
3873 // then the old method cannot be collected until sometime after
3874 // the old method call has returned. So the overwriting of old
3875 // methods by new methods will save us space except for those
3876 // (hopefully few) old methods that are still executing.
3877 //
3878 // A method refers to a ConstMethod* and this presents another
3879 // possible avenue to space savings. The ConstMethod* in the
3880 // new method contains possibly new attributes (LNT, LVT, etc).
3881 // At first glance, it seems possible to save space by replacing
3882 // the ConstMethod* in the old method with the ConstMethod*
3883 // from the new method. The old and new methods would share the
3884 // same ConstMethod* and we would save the space occupied by
3885 // the old ConstMethod*. However, the ConstMethod* contains
3886 // a back reference to the containing method. Sharing the
3887 // ConstMethod* between two methods could lead to confusion in
3888 // the code that uses the back reference. This would lead to
3889 // brittle code that could be broken in non-obvious ways now or
3890 // in the future.
3891 //
3892 // Another possibility is to copy the ConstMethod* from the new
3893 // method to the old method and then overwrite the new method with
3894 // the old method. Since the ConstMethod* contains the bytecodes
3895 // for the method embedded in the oop, this option would change
3896 // the bytecodes out from under any threads executing the old
3897 // method and make the thread's bcp invalid. Since EMCP requires
3898 // that the bytecodes be the same modulo constant pool indices, it
3899 // is straight forward to compute the correct new bcp in the new
3900 // ConstMethod* from the old bcp in the old ConstMethod*. The
3901 // time consuming part would be searching all the frames in all
3902 // of the threads to find all of the calls to the old method.
3903 //
3904 // It looks like we will have to live with the limited savings
3905 // that we get from effectively overwriting the old methods
3906 // when the new methods are attached to the_class.
3907
3908 // Count number of methods that are EMCP. The method will be marked
3909 // old but not obsolete if it is EMCP.
3910 emcp_method_count++;
3911
3912 // An EMCP method is _not_ obsolete. An obsolete method has a
3913 // different jmethodID than the current method. An EMCP method
3914 // has the same jmethodID as the current method. Having the
3915 // same jmethodID for all EMCP versions of a method allows for
3916 // a consistent view of the EMCP methods regardless of which
3917 // EMCP method you happen to have in hand. For example, a
3918 // breakpoint set in one EMCP method will work for all EMCP
3919 // versions of the method including the current one.
3920 } else {
3921 // mark obsolete methods as such
3922 old_method->set_is_obsolete();
3923 obsolete_count++;
3924
3925 // obsolete methods need a unique idnum so they become new entries in
3926 // the jmethodID cache in InstanceKlass
3927 assert(old_method->method_idnum() == new_method->method_idnum(), "must match");
3928 u2 num = InstanceKlass::cast(_the_class)->next_method_idnum();
3929 if (num != ConstMethod::UNSET_IDNUM) {
3930 old_method->set_method_idnum(num);
3931 }
3932
3933 // With tracing we try not to "yack" too much. The position of
3934 // this trace assumes there are fewer obsolete methods than
3935 // EMCP methods.
3936 if (log_is_enabled(Trace, redefine, class, obsolete, mark)) {
3937 ResourceMark rm;
3938 log_trace(redefine, class, obsolete, mark)
3939 ("mark %s(%s) as obsolete", old_method->name()->as_C_string(), old_method->signature()->as_C_string());
3940 }
3941 }
3942 old_method->set_is_old();
3943 }
3944 for (int i = 0; i < _deleted_methods_length; ++i) {
3945 Method* old_method = _deleted_methods[i];
3946
3947 assert(!old_method->has_vtable_index(),
3948 "cannot delete methods with vtable entries");;
3949
3950 // Mark all deleted methods as old, obsolete and deleted
3951 old_method->set_is_deleted();
3952 old_method->set_is_old();
3953 old_method->set_is_obsolete();
3954 ++obsolete_count;
3955 // With tracing we try not to "yack" too much. The position of
3956 // this trace assumes there are fewer obsolete methods than
3957 // EMCP methods.
3958 if (log_is_enabled(Trace, redefine, class, obsolete, mark)) {
3959 ResourceMark rm;
3960 log_trace(redefine, class, obsolete, mark)
3961 ("mark deleted %s(%s) as obsolete", old_method->name()->as_C_string(), old_method->signature()->as_C_string());
3962 }
3963 }
3964 assert((emcp_method_count + obsolete_count) == _old_methods->length(),
3965 "sanity check");
3966 log_trace(redefine, class, obsolete, mark)("EMCP_cnt=%d, obsolete_cnt=%d", emcp_method_count, obsolete_count);
3967 return emcp_method_count;
3968 }
3969
3970 // This internal class transfers the native function registration from old methods
3971 // to new methods. It is designed to handle both the simple case of unchanged
3972 // native methods and the complex cases of native method prefixes being added and/or
3973 // removed.
3974 // It expects only to be used during the VM_RedefineClasses op (a safepoint).
3975 //
3976 // This class is used after the new methods have been installed in "the_class".
3977 //
3978 // So, for example, the following must be handled. Where 'm' is a method and
3979 // a number followed by an underscore is a prefix.
3980 //
3981 // Old Name New Name
3982 // Simple transfer to new method m -> m
3983 // Add prefix m -> 1_m
3984 // Remove prefix 1_m -> m
3985 // Simultaneous add of prefixes m -> 3_2_1_m
3986 // Simultaneous removal of prefixes 3_2_1_m -> m
3987 // Simultaneous add and remove 1_m -> 2_m
3988 // Same, caused by prefix removal only 3_2_1_m -> 3_2_m
3989 //
3990 class TransferNativeFunctionRegistration {
3991 private:
3992 InstanceKlass* the_class;
3993 int prefix_count;
3994 char** prefixes;
3995
3996 // Recursively search the binary tree of possibly prefixed method names.
3997 // Iteration could be used if all agents were well behaved. Full tree walk is
3998 // more resilent to agents not cleaning up intermediate methods.
3999 // Branch at each depth in the binary tree is:
4000 // (1) without the prefix.
4001 // (2) with the prefix.
4002 // where 'prefix' is the prefix at that 'depth' (first prefix, second prefix,...)
4003 Method* search_prefix_name_space(int depth, char* name_str, size_t name_len,
4004 Symbol* signature) {
4005 TempNewSymbol name_symbol = SymbolTable::probe(name_str, (int)name_len);
4006 if (name_symbol != nullptr) {
4007 Method* method = the_class->lookup_method(name_symbol, signature);
4008 if (method != nullptr) {
4009 // Even if prefixed, intermediate methods must exist.
4010 if (method->is_native()) {
4011 // Wahoo, we found a (possibly prefixed) version of the method, return it.
4012 return method;
4013 }
4014 if (depth < prefix_count) {
4015 // Try applying further prefixes (other than this one).
4016 method = search_prefix_name_space(depth+1, name_str, name_len, signature);
4017 if (method != nullptr) {
4018 return method; // found
4019 }
4020
4021 // Try adding this prefix to the method name and see if it matches
4022 // another method name.
4023 char* prefix = prefixes[depth];
4024 size_t prefix_len = strlen(prefix);
4025 size_t trial_len = name_len + prefix_len;
4026 char* trial_name_str = NEW_RESOURCE_ARRAY(char, trial_len + 1);
4027 strcpy(trial_name_str, prefix);
4028 strcat(trial_name_str, name_str);
4029 method = search_prefix_name_space(depth+1, trial_name_str, trial_len,
4030 signature);
4031 if (method != nullptr) {
4032 // If found along this branch, it was prefixed, mark as such
4033 method->set_is_prefixed_native();
4034 return method; // found
4035 }
4036 }
4037 }
4038 }
4039 return nullptr; // This whole branch bore nothing
4040 }
4041
4042 // Return the method name with old prefixes stripped away.
4043 char* method_name_without_prefixes(Method* method) {
4044 Symbol* name = method->name();
4045 char* name_str = name->as_utf8();
4046
4047 // Old prefixing may be defunct, strip prefixes, if any.
4048 for (int i = prefix_count-1; i >= 0; i--) {
4049 char* prefix = prefixes[i];
4050 size_t prefix_len = strlen(prefix);
4051 if (strncmp(prefix, name_str, prefix_len) == 0) {
4052 name_str += prefix_len;
4053 }
4054 }
4055 return name_str;
4056 }
4057
4058 // Strip any prefixes off the old native method, then try to find a
4059 // (possibly prefixed) new native that matches it.
4060 Method* strip_and_search_for_new_native(Method* method) {
4061 ResourceMark rm;
4062 char* name_str = method_name_without_prefixes(method);
4063 return search_prefix_name_space(0, name_str, strlen(name_str),
4064 method->signature());
4065 }
4066
4067 public:
4068
4069 // Construct a native method transfer processor for this class.
4070 TransferNativeFunctionRegistration(InstanceKlass* _the_class) {
4071 assert(SafepointSynchronize::is_at_safepoint(), "sanity check");
4072
4073 the_class = _the_class;
4074 prefixes = JvmtiExport::get_all_native_method_prefixes(&prefix_count);
4075 }
4076
4077 // Attempt to transfer any of the old or deleted methods that are native
4078 void transfer_registrations(Method** old_methods, int methods_length) {
4079 for (int j = 0; j < methods_length; j++) {
4080 Method* old_method = old_methods[j];
4081
4082 if (old_method->is_native() && old_method->has_native_function()) {
4083 Method* new_method = strip_and_search_for_new_native(old_method);
4084 if (new_method != nullptr) {
4085 // Actually set the native function in the new method.
4086 // Redefine does not send events (except CFLH), certainly not this
4087 // behind the scenes re-registration.
4088 new_method->set_native_function(old_method->native_function(),
4089 !Method::native_bind_event_is_interesting);
4090 }
4091 }
4092 }
4093 }
4094 };
4095
4096 // Don't lose the association between a native method and its JNI function.
4097 void VM_RedefineClasses::transfer_old_native_function_registrations(InstanceKlass* the_class) {
4098 TransferNativeFunctionRegistration transfer(the_class);
4099 transfer.transfer_registrations(_deleted_methods, _deleted_methods_length);
4100 transfer.transfer_registrations(_matching_old_methods, _matching_methods_length);
4101 }
4102
4103 // Deoptimize all compiled code that depends on the classes redefined.
4104 //
4105 // If the can_redefine_classes capability is obtained in the onload
4106 // phase then the compiler has recorded all dependencies from startup.
4107 // In that case we need only deoptimize and throw away all compiled code
4108 // that depends on the class.
4109 //
4110 // If can_redefine_classes is obtained sometime after the onload
4111 // phase then the dependency information may be incomplete. In that case
4112 // the first call to RedefineClasses causes all compiled code to be
4113 // thrown away. As can_redefine_classes has been obtained then
4114 // all future compilations will record dependencies so second and
4115 // subsequent calls to RedefineClasses need only throw away code
4116 // that depends on the class.
4117 //
4118
4119 void VM_RedefineClasses::flush_dependent_code() {
4120 assert(SafepointSynchronize::is_at_safepoint(), "sanity check");
4121
4122 DeoptimizationScope deopt_scope;
4123
4124 // This is the first redefinition, mark all the nmethods for deoptimization
4125 if (!JvmtiExport::all_dependencies_are_recorded()) {
4126 CodeCache::mark_all_nmethods_for_evol_deoptimization(&deopt_scope);
4127 log_debug(redefine, class, nmethod)("Marked all nmethods for deopt");
4128 } else {
4129 CodeCache::mark_dependents_for_evol_deoptimization(&deopt_scope);
4130 log_debug(redefine, class, nmethod)("Marked dependent nmethods for deopt");
4131 }
4132
4133 deopt_scope.deoptimize_marked();
4134
4135 // From now on we know that the dependency information is complete
4136 JvmtiExport::set_all_dependencies_are_recorded(true);
4137 }
4138
4139 void VM_RedefineClasses::compute_added_deleted_matching_methods() {
4140 Method* old_method;
4141 Method* new_method;
4142
4143 _matching_old_methods = NEW_RESOURCE_ARRAY(Method*, _old_methods->length());
4144 _matching_new_methods = NEW_RESOURCE_ARRAY(Method*, _old_methods->length());
4145 _added_methods = NEW_RESOURCE_ARRAY(Method*, _new_methods->length());
4146 _deleted_methods = NEW_RESOURCE_ARRAY(Method*, _old_methods->length());
4147
4148 _matching_methods_length = 0;
4149 _deleted_methods_length = 0;
4150 _added_methods_length = 0;
4151
4152 int nj = 0;
4153 int oj = 0;
4154 while (true) {
4155 if (oj >= _old_methods->length()) {
4156 if (nj >= _new_methods->length()) {
4157 break; // we've looked at everything, done
4158 }
4159 // New method at the end
4160 new_method = _new_methods->at(nj);
4161 _added_methods[_added_methods_length++] = new_method;
4162 ++nj;
4163 } else if (nj >= _new_methods->length()) {
4164 // Old method, at the end, is deleted
4165 old_method = _old_methods->at(oj);
4166 _deleted_methods[_deleted_methods_length++] = old_method;
4167 ++oj;
4168 } else {
4169 old_method = _old_methods->at(oj);
4170 new_method = _new_methods->at(nj);
4171 if (old_method->name() == new_method->name()) {
4172 if (old_method->signature() == new_method->signature()) {
4173 _matching_old_methods[_matching_methods_length ] = old_method;
4174 _matching_new_methods[_matching_methods_length++] = new_method;
4175 ++nj;
4176 ++oj;
4177 } else {
4178 // added overloaded have already been moved to the end,
4179 // so this is a deleted overloaded method
4180 _deleted_methods[_deleted_methods_length++] = old_method;
4181 ++oj;
4182 }
4183 } else { // names don't match
4184 if (old_method->name()->fast_compare(new_method->name()) > 0) {
4185 // new method
4186 _added_methods[_added_methods_length++] = new_method;
4187 ++nj;
4188 } else {
4189 // deleted method
4190 _deleted_methods[_deleted_methods_length++] = old_method;
4191 ++oj;
4192 }
4193 }
4194 }
4195 }
4196 assert(_matching_methods_length + _deleted_methods_length == _old_methods->length(), "sanity");
4197 assert(_matching_methods_length + _added_methods_length == _new_methods->length(), "sanity");
4198 }
4199
4200
4201 void VM_RedefineClasses::swap_annotations(InstanceKlass* the_class,
4202 InstanceKlass* scratch_class) {
4203 // Swap annotation fields values
4204 Annotations* old_annotations = the_class->annotations();
4205 the_class->set_annotations(scratch_class->annotations());
4206 scratch_class->set_annotations(old_annotations);
4207 }
4208
4209
4210 // Install the redefinition of a class:
4211 // - house keeping (flushing breakpoints and caches, deoptimizing
4212 // dependent compiled code)
4213 // - replacing parts in the_class with parts from scratch_class
4214 // - adding a weak reference to track the obsolete but interesting
4215 // parts of the_class
4216 // - adjusting constant pool caches and vtables in other classes
4217 // that refer to methods in the_class. These adjustments use the
4218 // ClassLoaderDataGraph::classes_do() facility which only allows
4219 // a helper method to be specified. The interesting parameters
4220 // that we would like to pass to the helper method are saved in
4221 // static global fields in the VM operation.
4222 void VM_RedefineClasses::redefine_single_class(Thread* current, jclass the_jclass,
4223 InstanceKlass* scratch_class) {
4224
4225 HandleMark hm(current); // make sure handles from this call are freed
4226
4227 if (log_is_enabled(Info, redefine, class, timer)) {
4228 _timer_rsc_phase1.start();
4229 }
4230
4231 InstanceKlass* the_class = get_ik(the_jclass);
4232
4233 // Set a flag to control and optimize adjusting method entries
4234 _has_redefined_Object |= the_class == vmClasses::Object_klass();
4235
4236 // Remove all breakpoints in methods of this class
4237 JvmtiBreakpoints& jvmti_breakpoints = JvmtiCurrentBreakpoints::get_jvmti_breakpoints();
4238 jvmti_breakpoints.clearall_in_class_at_safepoint(the_class);
4239
4240 _old_methods = the_class->methods();
4241 _new_methods = scratch_class->methods();
4242 _the_class = the_class;
4243 compute_added_deleted_matching_methods();
4244 update_jmethod_ids();
4245
4246 _any_class_has_resolved_methods = the_class->has_resolved_methods() || _any_class_has_resolved_methods;
4247
4248 // Attach new constant pool to the original klass. The original
4249 // klass still refers to the old constant pool (for now).
4250 scratch_class->constants()->set_pool_holder(the_class);
4251
4252 #if 0
4253 // In theory, with constant pool merging in place we should be able
4254 // to save space by using the new, merged constant pool in place of
4255 // the old constant pool(s). By "pool(s)" I mean the constant pool in
4256 // the klass version we are replacing now and any constant pool(s) in
4257 // previous versions of klass. Nice theory, doesn't work in practice.
4258 // When this code is enabled, even simple programs throw NullPointer
4259 // exceptions. I'm guessing that this is caused by some constant pool
4260 // cache difference between the new, merged constant pool and the
4261 // constant pool that was just being used by the klass. I'm keeping
4262 // this code around to archive the idea, but the code has to remain
4263 // disabled for now.
4264
4265 // Attach each old method to the new constant pool. This can be
4266 // done here since we are past the bytecode verification and
4267 // constant pool optimization phases.
4268 for (int i = _old_methods->length() - 1; i >= 0; i--) {
4269 Method* method = _old_methods->at(i);
4270 method->set_constants(scratch_class->constants());
4271 }
4272
4273 // NOTE: this doesn't work because you can redefine the same class in two
4274 // threads, each getting their own constant pool data appended to the
4275 // original constant pool. In order for the new methods to work when they
4276 // become old methods, they need to keep their updated copy of the constant pool.
4277
4278 {
4279 // walk all previous versions of the klass
4280 InstanceKlass *ik = the_class;
4281 PreviousVersionWalker pvw(ik);
4282 do {
4283 ik = pvw.next_previous_version();
4284 if (ik != nullptr) {
4285
4286 // attach previous version of klass to the new constant pool
4287 ik->set_constants(scratch_class->constants());
4288
4289 // Attach each method in the previous version of klass to the
4290 // new constant pool
4291 Array<Method*>* prev_methods = ik->methods();
4292 for (int i = prev_methods->length() - 1; i >= 0; i--) {
4293 Method* method = prev_methods->at(i);
4294 method->set_constants(scratch_class->constants());
4295 }
4296 }
4297 } while (ik != nullptr);
4298 }
4299 #endif
4300
4301 // Replace methods and constantpool
4302 the_class->set_methods(_new_methods);
4303 scratch_class->set_methods(_old_methods); // To prevent potential GCing of the old methods,
4304 // and to be able to undo operation easily.
4305
4306 Array<int>* old_ordering = the_class->method_ordering();
4307 the_class->set_method_ordering(scratch_class->method_ordering());
4308 scratch_class->set_method_ordering(old_ordering);
4309
4310 ConstantPool* old_constants = the_class->constants();
4311 the_class->set_constants(scratch_class->constants());
4312 scratch_class->set_constants(old_constants); // See the previous comment.
4313 #if 0
4314 // We are swapping the guts of "the new class" with the guts of "the
4315 // class". Since the old constant pool has just been attached to "the
4316 // new class", it seems logical to set the pool holder in the old
4317 // constant pool also. However, doing this will change the observable
4318 // class hierarchy for any old methods that are still executing. A
4319 // method can query the identity of its "holder" and this query uses
4320 // the method's constant pool link to find the holder. The change in
4321 // holding class from "the class" to "the new class" can confuse
4322 // things.
4323 //
4324 // Setting the old constant pool's holder will also cause
4325 // verification done during vtable initialization below to fail.
4326 // During vtable initialization, the vtable's class is verified to be
4327 // a subtype of the method's holder. The vtable's class is "the
4328 // class" and the method's holder is gotten from the constant pool
4329 // link in the method itself. For "the class"'s directly implemented
4330 // methods, the method holder is "the class" itself (as gotten from
4331 // the new constant pool). The check works fine in this case. The
4332 // check also works fine for methods inherited from super classes.
4333 //
4334 // Miranda methods are a little more complicated. A miranda method is
4335 // provided by an interface when the class implementing the interface
4336 // does not provide its own method. These interfaces are implemented
4337 // internally as an InstanceKlass. These special instanceKlasses
4338 // share the constant pool of the class that "implements" the
4339 // interface. By sharing the constant pool, the method holder of a
4340 // miranda method is the class that "implements" the interface. In a
4341 // non-redefine situation, the subtype check works fine. However, if
4342 // the old constant pool's pool holder is modified, then the check
4343 // fails because there is no class hierarchy relationship between the
4344 // vtable's class and "the new class".
4345
4346 old_constants->set_pool_holder(scratch_class());
4347 #endif
4348
4349 // track number of methods that are EMCP for add_previous_version() call below
4350 int emcp_method_count = check_methods_and_mark_as_obsolete();
4351 transfer_old_native_function_registrations(the_class);
4352
4353 if (scratch_class->get_cached_class_file() != the_class->get_cached_class_file()) {
4354 // 1. the_class doesn't have a cache yet, scratch_class does have a cache.
4355 // 2. The same class can be present twice in the scratch classes list or there
4356 // are multiple concurrent RetransformClasses calls on different threads.
4357 // the_class and scratch_class have the same cached bytes, but different buffers.
4358 // In such cases we need to deallocate one of the buffers.
4359 // 3. RedefineClasses and the_class has cached bytes from a previous transformation.
4360 // In the case we need to use class bytes from scratch_class.
4361 if (the_class->get_cached_class_file() != nullptr) {
4362 os::free(the_class->get_cached_class_file());
4363 }
4364 the_class->set_cached_class_file(scratch_class->get_cached_class_file());
4365 }
4366
4367 // null out in scratch class to not delete twice. The class to be redefined
4368 // always owns these bytes.
4369 scratch_class->set_cached_class_file(nullptr);
4370
4371 // Replace inner_classes
4372 Array<u2>* old_inner_classes = the_class->inner_classes();
4373 the_class->set_inner_classes(scratch_class->inner_classes());
4374 scratch_class->set_inner_classes(old_inner_classes);
4375
4376 // Initialize the vtable and interface table after
4377 // methods have been rewritten
4378 // no exception should happen here since we explicitly
4379 // do not check loader constraints.
4380 // compare_and_normalize_class_versions has already checked:
4381 // - classloaders unchanged, signatures unchanged
4382 // - all instanceKlasses for redefined classes reused & contents updated
4383 the_class->vtable().initialize_vtable();
4384 the_class->itable().initialize_itable();
4385
4386 // Leave arrays of jmethodIDs and itable index cache unchanged
4387
4388 // Copy the "source debug extension" attribute from new class version
4389 the_class->set_source_debug_extension(
4390 scratch_class->source_debug_extension(),
4391 scratch_class->source_debug_extension() == nullptr ? 0 :
4392 (int)strlen(scratch_class->source_debug_extension()));
4393
4394 // Use of javac -g could be different in the old and the new
4395 if (scratch_class->has_localvariable_table() !=
4396 the_class->has_localvariable_table()) {
4397 the_class->set_has_localvariable_table(scratch_class->has_localvariable_table());
4398 }
4399
4400 swap_annotations(the_class, scratch_class);
4401
4402 // Replace minor version number of class file
4403 u2 old_minor_version = the_class->constants()->minor_version();
4404 the_class->constants()->set_minor_version(scratch_class->constants()->minor_version());
4405 scratch_class->constants()->set_minor_version(old_minor_version);
4406
4407 // Replace major version number of class file
4408 u2 old_major_version = the_class->constants()->major_version();
4409 the_class->constants()->set_major_version(scratch_class->constants()->major_version());
4410 scratch_class->constants()->set_major_version(old_major_version);
4411
4412 // Replace CP indexes for class and name+type of enclosing method
4413 u2 old_class_idx = the_class->enclosing_method_class_index();
4414 u2 old_method_idx = the_class->enclosing_method_method_index();
4415 the_class->set_enclosing_method_indices(
4416 scratch_class->enclosing_method_class_index(),
4417 scratch_class->enclosing_method_method_index());
4418 scratch_class->set_enclosing_method_indices(old_class_idx, old_method_idx);
4419
4420 if (!the_class->has_been_redefined()) {
4421 the_class->set_has_been_redefined();
4422 }
4423
4424 // Scratch class is unloaded but still needs cleaning, and skipping for CDS.
4425 scratch_class->set_is_scratch_class();
4426
4427 // keep track of previous versions of this class
4428 the_class->add_previous_version(scratch_class, emcp_method_count);
4429
4430 _timer_rsc_phase1.stop();
4431 if (log_is_enabled(Info, redefine, class, timer)) {
4432 _timer_rsc_phase2.start();
4433 }
4434
4435 if (the_class->oop_map_cache() != nullptr) {
4436 // Flush references to any obsolete methods from the oop map cache
4437 // so that obsolete methods are not pinned.
4438 the_class->oop_map_cache()->flush_obsolete_entries();
4439 }
4440
4441 increment_class_counter(the_class);
4442
4443 if (EventClassRedefinition::is_enabled()) {
4444 EventClassRedefinition event;
4445 event.set_classModificationCount(java_lang_Class::classRedefinedCount(the_class->java_mirror()));
4446 event.set_redefinedClass(the_class);
4447 event.set_redefinitionId(_id);
4448 event.commit();
4449 }
4450
4451 {
4452 ResourceMark rm(current);
4453 // increment the classRedefinedCount field in the_class and in any
4454 // direct and indirect subclasses of the_class
4455 log_info(redefine, class, load)
4456 ("redefined name=%s, count=%d (avail_mem=" UINT64_FORMAT "K)",
4457 the_class->external_name(), java_lang_Class::classRedefinedCount(the_class->java_mirror()), os::available_memory() >> 10);
4458 Events::log_redefinition(current, "redefined class name=%s, count=%d",
4459 the_class->external_name(),
4460 java_lang_Class::classRedefinedCount(the_class->java_mirror()));
4461
4462 }
4463 _timer_rsc_phase2.stop();
4464
4465 } // end redefine_single_class()
4466
4467
4468 // Increment the classRedefinedCount field in the specific InstanceKlass
4469 // and in all direct and indirect subclasses.
4470 void VM_RedefineClasses::increment_class_counter(InstanceKlass* ik) {
4471 for (ClassHierarchyIterator iter(ik); !iter.done(); iter.next()) {
4472 // Only update instanceKlasses
4473 Klass* sub = iter.klass();
4474 if (sub->is_instance_klass()) {
4475 oop class_mirror = InstanceKlass::cast(sub)->java_mirror();
4476 Klass* class_oop = java_lang_Class::as_Klass(class_mirror);
4477 int new_count = java_lang_Class::classRedefinedCount(class_mirror) + 1;
4478 java_lang_Class::set_classRedefinedCount(class_mirror, new_count);
4479
4480 if (class_oop != _the_class) {
4481 // _the_class count is printed at end of redefine_single_class()
4482 log_debug(redefine, class, subclass)("updated count in subclass=%s to %d", ik->external_name(), new_count);
4483 }
4484 }
4485 }
4486 }
4487
4488 void VM_RedefineClasses::CheckClass::do_klass(Klass* k) {
4489 bool no_old_methods = true; // be optimistic
4490
4491 // Both array and instance classes have vtables.
4492 // a vtable should never contain old or obsolete methods
4493 ResourceMark rm(_thread);
4494 if (k->vtable_length() > 0 &&
4495 !k->vtable().check_no_old_or_obsolete_entries()) {
4496 if (log_is_enabled(Trace, redefine, class, obsolete, metadata)) {
4497 log_trace(redefine, class, obsolete, metadata)
4498 ("klassVtable::check_no_old_or_obsolete_entries failure -- OLD or OBSOLETE method found -- class: %s",
4499 k->signature_name());
4500 k->vtable().dump_vtable();
4501 }
4502 no_old_methods = false;
4503 }
4504
4505 if (k->is_instance_klass()) {
4506 HandleMark hm(_thread);
4507 InstanceKlass *ik = InstanceKlass::cast(k);
4508
4509 // an itable should never contain old or obsolete methods
4510 if (ik->itable_length() > 0 &&
4511 !ik->itable().check_no_old_or_obsolete_entries()) {
4512 if (log_is_enabled(Trace, redefine, class, obsolete, metadata)) {
4513 log_trace(redefine, class, obsolete, metadata)
4514 ("klassItable::check_no_old_or_obsolete_entries failure -- OLD or OBSOLETE method found -- class: %s",
4515 ik->signature_name());
4516 ik->itable().dump_itable();
4517 }
4518 no_old_methods = false;
4519 }
4520
4521 // the constant pool cache should never contain non-deleted old or obsolete methods
4522 if (ik->constants() != nullptr &&
4523 ik->constants()->cache() != nullptr &&
4524 !ik->constants()->cache()->check_no_old_or_obsolete_entries()) {
4525 if (log_is_enabled(Trace, redefine, class, obsolete, metadata)) {
4526 log_trace(redefine, class, obsolete, metadata)
4527 ("cp-cache::check_no_old_or_obsolete_entries failure -- OLD or OBSOLETE method found -- class: %s",
4528 ik->signature_name());
4529 ik->constants()->cache()->dump_cache();
4530 }
4531 no_old_methods = false;
4532 }
4533 }
4534
4535 // print and fail guarantee if old methods are found.
4536 if (!no_old_methods) {
4537 if (log_is_enabled(Trace, redefine, class, obsolete, metadata)) {
4538 dump_methods();
4539 } else {
4540 log_trace(redefine, class)("Use the '-Xlog:redefine+class*:' option "
4541 "to see more info about the following guarantee() failure.");
4542 }
4543 guarantee(false, "OLD and/or OBSOLETE method(s) found");
4544 }
4545 }
4546
4547 u8 VM_RedefineClasses::next_id() {
4548 while (true) {
4549 u8 id = _id_counter;
4550 u8 next_id = id + 1;
4551 u8 result = Atomic::cmpxchg(&_id_counter, id, next_id);
4552 if (result == id) {
4553 return next_id;
4554 }
4555 }
4556 }
4557
4558 void VM_RedefineClasses::dump_methods() {
4559 int j;
4560 log_trace(redefine, class, dump)("_old_methods --");
4561 for (j = 0; j < _old_methods->length(); ++j) {
4562 LogStreamHandle(Trace, redefine, class, dump) log_stream;
4563 Method* m = _old_methods->at(j);
4564 log_stream.print("%4d (%5d) ", j, m->vtable_index());
4565 m->access_flags().print_on(&log_stream);
4566 log_stream.print(" -- ");
4567 m->print_name(&log_stream);
4568 log_stream.cr();
4569 }
4570 log_trace(redefine, class, dump)("_new_methods --");
4571 for (j = 0; j < _new_methods->length(); ++j) {
4572 LogStreamHandle(Trace, redefine, class, dump) log_stream;
4573 Method* m = _new_methods->at(j);
4574 log_stream.print("%4d (%5d) ", j, m->vtable_index());
4575 m->access_flags().print_on(&log_stream);
4576 log_stream.print(" -- ");
4577 m->print_name(&log_stream);
4578 log_stream.cr();
4579 }
4580 log_trace(redefine, class, dump)("_matching_methods --");
4581 for (j = 0; j < _matching_methods_length; ++j) {
4582 LogStreamHandle(Trace, redefine, class, dump) log_stream;
4583 Method* m = _matching_old_methods[j];
4584 log_stream.print("%4d (%5d) ", j, m->vtable_index());
4585 m->access_flags().print_on(&log_stream);
4586 log_stream.print(" -- ");
4587 m->print_name();
4588 log_stream.cr();
4589
4590 m = _matching_new_methods[j];
4591 log_stream.print(" (%5d) ", m->vtable_index());
4592 m->access_flags().print_on(&log_stream);
4593 log_stream.cr();
4594 }
4595 log_trace(redefine, class, dump)("_deleted_methods --");
4596 for (j = 0; j < _deleted_methods_length; ++j) {
4597 LogStreamHandle(Trace, redefine, class, dump) log_stream;
4598 Method* m = _deleted_methods[j];
4599 log_stream.print("%4d (%5d) ", j, m->vtable_index());
4600 m->access_flags().print_on(&log_stream);
4601 log_stream.print(" -- ");
4602 m->print_name(&log_stream);
4603 log_stream.cr();
4604 }
4605 log_trace(redefine, class, dump)("_added_methods --");
4606 for (j = 0; j < _added_methods_length; ++j) {
4607 LogStreamHandle(Trace, redefine, class, dump) log_stream;
4608 Method* m = _added_methods[j];
4609 log_stream.print("%4d (%5d) ", j, m->vtable_index());
4610 m->access_flags().print_on(&log_stream);
4611 log_stream.print(" -- ");
4612 m->print_name(&log_stream);
4613 log_stream.cr();
4614 }
4615 }
4616
4617 void VM_RedefineClasses::print_on_error(outputStream* st) const {
4618 VM_Operation::print_on_error(st);
4619 if (_the_class != nullptr) {
4620 ResourceMark rm;
4621 st->print_cr(", redefining class %s", _the_class->external_name());
4622 }
4623 }