1 /*
2 * Copyright (c) 2003, 2025, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
24
25 #include "cds/cdsConfig.hpp"
26 #include "cds/metaspaceShared.hpp"
27 #include "classfile/classFileStream.hpp"
28 #include "classfile/classLoaderDataGraph.hpp"
29 #include "classfile/classLoadInfo.hpp"
30 #include "classfile/klassFactory.hpp"
31 #include "classfile/javaClasses.inline.hpp"
32 #include "classfile/metadataOnStackMark.hpp"
33 #include "classfile/stackMapTable.hpp"
34 #include "classfile/symbolTable.hpp"
35 #include "classfile/verifier.hpp"
36 #include "classfile/vmClasses.hpp"
37 #include "classfile/vmSymbols.hpp"
38 #include "code/codeCache.hpp"
39 #include "compiler/compileBroker.hpp"
40 #include "interpreter/oopMapCache.hpp"
41 #include "interpreter/rewriter.hpp"
42 #include "jfr/jfrEvents.hpp"
43 #include "logging/logStream.hpp"
44 #include "memory/metadataFactory.hpp"
45 #include "memory/resourceArea.hpp"
46 #include "memory/universe.hpp"
47 #include "oops/annotations.hpp"
48 #include "oops/constantPool.hpp"
49 #include "oops/fieldStreams.inline.hpp"
50 #include "oops/klass.inline.hpp"
51 #include "oops/klassVtable.hpp"
52 #include "oops/method.hpp"
53 #include "oops/oop.inline.hpp"
54 #include "oops/recordComponent.hpp"
55 #include "prims/jvmtiImpl.hpp"
56 #include "prims/jvmtiRedefineClasses.hpp"
57 #include "prims/jvmtiThreadState.inline.hpp"
58 #include "prims/resolvedMethodTable.hpp"
59 #include "prims/methodComparator.hpp"
60 #include "runtime/atomic.hpp"
61 #include "runtime/deoptimization.hpp"
62 #include "runtime/handles.inline.hpp"
63 #include "runtime/jniHandles.inline.hpp"
64 #include "runtime/relocator.hpp"
65 #include "runtime/safepointVerifiers.hpp"
66 #include "utilities/bitMap.inline.hpp"
67 #include "utilities/checkedCast.hpp"
68 #include "utilities/events.hpp"
69 #include "utilities/macros.hpp"
70
71 Array<Method*>* VM_RedefineClasses::_old_methods = nullptr;
72 Array<Method*>* VM_RedefineClasses::_new_methods = nullptr;
73 Method** VM_RedefineClasses::_matching_old_methods = nullptr;
74 Method** VM_RedefineClasses::_matching_new_methods = nullptr;
75 Method** VM_RedefineClasses::_deleted_methods = nullptr;
76 Method** VM_RedefineClasses::_added_methods = nullptr;
77 int VM_RedefineClasses::_matching_methods_length = 0;
78 int VM_RedefineClasses::_deleted_methods_length = 0;
79 int VM_RedefineClasses::_added_methods_length = 0;
80
81 // This flag is global as the constructor does not reset it:
82 bool VM_RedefineClasses::_has_redefined_Object = false;
83 u8 VM_RedefineClasses::_id_counter = 0;
84
85 VM_RedefineClasses::VM_RedefineClasses(jint class_count,
86 const jvmtiClassDefinition *class_defs,
87 JvmtiClassLoadKind class_load_kind) {
88 _class_count = class_count;
89 _class_defs = class_defs;
90 _class_load_kind = class_load_kind;
91 _any_class_has_resolved_methods = false;
92 _res = JVMTI_ERROR_NONE;
93 _the_class = nullptr;
94 _id = next_id();
95 }
96
97 static inline InstanceKlass* get_ik(jclass def) {
98 oop mirror = JNIHandles::resolve_non_null(def);
99 return InstanceKlass::cast(java_lang_Class::as_Klass(mirror));
100 }
101
102 // If any of the classes are being redefined, wait
103 // Parallel constant pool merging leads to indeterminate constant pools.
104 void VM_RedefineClasses::lock_classes() {
105 JvmtiThreadState *state = JvmtiThreadState::state_for(JavaThread::current());
106 GrowableArray<Klass*>* redef_classes = state->get_classes_being_redefined();
107
108 MonitorLocker ml(RedefineClasses_lock);
109
110 if (redef_classes == nullptr) {
111 redef_classes = new (mtClass) GrowableArray<Klass*>(1, mtClass);
112 state->set_classes_being_redefined(redef_classes);
113 }
114
115 bool has_redefined;
116 do {
117 has_redefined = false;
118 // Go through classes each time until none are being redefined. Skip
119 // the ones that are being redefined by this thread currently. Class file
120 // load hook event may trigger new class redefine when we are redefining
121 // a class (after lock_classes()).
122 for (int i = 0; i < _class_count; i++) {
123 InstanceKlass* ik = get_ik(_class_defs[i].klass);
124 // Check if we are currently redefining the class in this thread already.
125 if (redef_classes->contains(ik)) {
126 assert(ik->is_being_redefined(), "sanity");
127 } else {
128 if (ik->is_being_redefined()) {
129 ml.wait();
130 has_redefined = true;
131 break; // for loop
132 }
133 }
134 }
135 } while (has_redefined);
136
137 for (int i = 0; i < _class_count; i++) {
138 InstanceKlass* ik = get_ik(_class_defs[i].klass);
139 redef_classes->push(ik); // Add to the _classes_being_redefined list
140 ik->set_is_being_redefined(true);
141 }
142 ml.notify_all();
143 }
144
145 void VM_RedefineClasses::unlock_classes() {
146 JvmtiThreadState *state = JvmtiThreadState::state_for(JavaThread::current());
147 GrowableArray<Klass*>* redef_classes = state->get_classes_being_redefined();
148 assert(redef_classes != nullptr, "_classes_being_redefined is not allocated");
149
150 MonitorLocker ml(RedefineClasses_lock);
151
152 for (int i = _class_count - 1; i >= 0; i--) {
153 InstanceKlass* def_ik = get_ik(_class_defs[i].klass);
154 if (redef_classes->length() > 0) {
155 // Remove the class from _classes_being_redefined list
156 Klass* k = redef_classes->pop();
157 assert(def_ik == k, "unlocking wrong class");
158 }
159 assert(def_ik->is_being_redefined(),
160 "should be being redefined to get here");
161
162 // Unlock after we finish all redefines for this class within
163 // the thread. Same class can be pushed to the list multiple
164 // times (not more than once by each recursive redefinition).
165 if (!redef_classes->contains(def_ik)) {
166 def_ik->set_is_being_redefined(false);
167 }
168 }
169 ml.notify_all();
170 }
171
172 bool VM_RedefineClasses::doit_prologue() {
173 if (_class_count == 0) {
174 _res = JVMTI_ERROR_NONE;
175 return false;
176 }
177 if (_class_defs == nullptr) {
178 _res = JVMTI_ERROR_NULL_POINTER;
179 return false;
180 }
181
182 for (int i = 0; i < _class_count; i++) {
183 if (_class_defs[i].klass == nullptr) {
184 _res = JVMTI_ERROR_INVALID_CLASS;
185 return false;
186 }
187 if (_class_defs[i].class_byte_count == 0) {
188 _res = JVMTI_ERROR_INVALID_CLASS_FORMAT;
189 return false;
190 }
191 if (_class_defs[i].class_bytes == nullptr) {
192 _res = JVMTI_ERROR_NULL_POINTER;
193 return false;
194 }
195
196 oop mirror = JNIHandles::resolve_non_null(_class_defs[i].klass);
197 // classes for primitives, arrays, and hidden classes
198 // cannot be redefined.
199 if (!is_modifiable_class(mirror)) {
200 _res = JVMTI_ERROR_UNMODIFIABLE_CLASS;
201 return false;
202 }
203 }
204
205 // Start timer after all the sanity checks; not quite accurate, but
206 // better than adding a bunch of stop() calls.
207 if (log_is_enabled(Info, redefine, class, timer)) {
208 _timer_vm_op_prologue.start();
209 }
210
211 lock_classes();
212 // We first load new class versions in the prologue, because somewhere down the
213 // call chain it is required that the current thread is a Java thread.
214 _res = load_new_class_versions();
215 if (_res != JVMTI_ERROR_NONE) {
216 // free any successfully created classes, since none are redefined
217 for (int i = 0; i < _class_count; i++) {
218 if (_scratch_classes[i] != nullptr) {
219 ClassLoaderData* cld = _scratch_classes[i]->class_loader_data();
220 // Free the memory for this class at class unloading time. Not before
221 // because CMS might think this is still live.
222 InstanceKlass* ik = get_ik(_class_defs[i].klass);
223 if (ik->get_cached_class_file() == _scratch_classes[i]->get_cached_class_file()) {
224 // Don't double-free cached_class_file copied from the original class if error.
225 _scratch_classes[i]->set_cached_class_file(nullptr);
226 }
227 cld->add_to_deallocate_list(InstanceKlass::cast(_scratch_classes[i]));
228 }
229 }
230 // Free os::malloc allocated memory in load_new_class_version.
231 os::free(_scratch_classes);
232 _timer_vm_op_prologue.stop();
233 unlock_classes();
234 return false;
235 }
236
237 _timer_vm_op_prologue.stop();
238 return true;
239 }
240
241 void VM_RedefineClasses::doit() {
242 Thread* current = Thread::current();
243
244 if (log_is_enabled(Info, redefine, class, timer)) {
245 _timer_vm_op_doit.start();
246 }
247
248 #if INCLUDE_CDS
249 if (CDSConfig::is_using_archive()) {
250 // Sharing is enabled so we remap the shared readonly space to
251 // shared readwrite, private just in case we need to redefine
252 // a shared class. We do the remap during the doit() phase of
253 // the safepoint to be safer.
254 if (!MetaspaceShared::remap_shared_readonly_as_readwrite()) {
255 log_info(redefine, class, load)("failed to remap shared readonly space to readwrite, private");
256 _res = JVMTI_ERROR_INTERNAL;
257 _timer_vm_op_doit.stop();
258 return;
259 }
260 }
261 #endif
262
263 // Mark methods seen on stack and everywhere else so old methods are not
264 // cleaned up if they're on the stack.
265 MetadataOnStackMark md_on_stack(/*walk_all_metadata*/true, /*redefinition_walk*/true);
266 HandleMark hm(current); // make sure any handles created are deleted
267 // before the stack walk again.
268
269 for (int i = 0; i < _class_count; i++) {
270 redefine_single_class(current, _class_defs[i].klass, _scratch_classes[i]);
271 }
272
273 // Flush all compiled code that depends on the classes redefined.
274 flush_dependent_code();
275
276 // Adjust constantpool caches and vtables for all classes
277 // that reference methods of the evolved classes.
278 // Have to do this after all classes are redefined and all methods that
279 // are redefined are marked as old.
280 AdjustAndCleanMetadata adjust_and_clean_metadata(current);
281 ClassLoaderDataGraph::classes_do(&adjust_and_clean_metadata);
282
283 // JSR-292 support
284 if (_any_class_has_resolved_methods) {
285 bool trace_name_printed = false;
286 ResolvedMethodTable::adjust_method_entries(&trace_name_printed);
287 }
288
289 // Increment flag indicating that some invariants are no longer true.
290 // See jvmtiExport.hpp for detailed explanation.
291 JvmtiExport::increment_redefinition_count();
292
293 // check_class() is optionally called for product bits, but is
294 // always called for non-product bits.
295 #ifdef PRODUCT
296 if (log_is_enabled(Trace, redefine, class, obsolete, metadata)) {
297 #endif
298 log_trace(redefine, class, obsolete, metadata)("calling check_class");
299 CheckClass check_class(current);
300 ClassLoaderDataGraph::classes_do(&check_class);
301 #ifdef PRODUCT
302 }
303 #endif
304
305 // Clean up any metadata now unreferenced while MetadataOnStackMark is set.
306 ClassLoaderDataGraph::clean_deallocate_lists(false);
307
308 _timer_vm_op_doit.stop();
309 }
310
311 void VM_RedefineClasses::doit_epilogue() {
312 unlock_classes();
313
314 // Free os::malloc allocated memory.
315 os::free(_scratch_classes);
316
317 // Reset the_class to null for error printing.
318 _the_class = nullptr;
319
320 if (log_is_enabled(Info, redefine, class, timer)) {
321 // Used to have separate timers for "doit" and "all", but the timer
322 // overhead skewed the measurements.
323 julong doit_time = _timer_vm_op_doit.milliseconds();
324 julong all_time = _timer_vm_op_prologue.milliseconds() + doit_time;
325
326 log_info(redefine, class, timer)
327 ("vm_op: all=" JULONG_FORMAT " prologue=" JULONG_FORMAT " doit=" JULONG_FORMAT,
328 all_time, (julong)_timer_vm_op_prologue.milliseconds(), doit_time);
329 log_info(redefine, class, timer)
330 ("redefine_single_class: phase1=" JULONG_FORMAT " phase2=" JULONG_FORMAT,
331 (julong)_timer_rsc_phase1.milliseconds(), (julong)_timer_rsc_phase2.milliseconds());
332 }
333 }
334
335 bool VM_RedefineClasses::is_modifiable_class(oop klass_mirror) {
336 // classes for primitives cannot be redefined
337 if (java_lang_Class::is_primitive(klass_mirror)) {
338 return false;
339 }
340 Klass* k = java_lang_Class::as_Klass(klass_mirror);
341 // classes for arrays cannot be redefined
342 if (k == nullptr || !k->is_instance_klass()) {
343 return false;
344 }
345
346 // Cannot redefine or retransform a hidden class.
347 if (InstanceKlass::cast(k)->is_hidden()) {
348 return false;
349 }
350 if (InstanceKlass::cast(k) == vmClasses::Continuation_klass()) {
351 // Don't redefine Continuation class. See 8302779.
352 return false;
353 }
354 return true;
355 }
356
357 // Append the current entry at scratch_i in scratch_cp to *merge_cp_p
358 // where the end of *merge_cp_p is specified by *merge_cp_length_p. For
359 // direct CP entries, there is just the current entry to append. For
360 // indirect and double-indirect CP entries, there are zero or more
361 // referenced CP entries along with the current entry to append.
362 // Indirect and double-indirect CP entries are handled by recursive
363 // calls to append_entry() as needed. The referenced CP entries are
364 // always appended to *merge_cp_p before the referee CP entry. These
365 // referenced CP entries may already exist in *merge_cp_p in which case
366 // there is nothing extra to append and only the current entry is
367 // appended.
368 void VM_RedefineClasses::append_entry(const constantPoolHandle& scratch_cp,
369 int scratch_i, constantPoolHandle *merge_cp_p, int *merge_cp_length_p) {
370
371 // append is different depending on entry tag type
372 switch (scratch_cp->tag_at(scratch_i).value()) {
373
374 // The old verifier is implemented outside the VM. It loads classes,
375 // but does not resolve constant pool entries directly so we never
376 // see Class entries here with the old verifier. Similarly the old
377 // verifier does not like Class entries in the input constant pool.
378 // The split-verifier is implemented in the VM so it can optionally
379 // and directly resolve constant pool entries to load classes. The
380 // split-verifier can accept either Class entries or UnresolvedClass
381 // entries in the input constant pool. We revert the appended copy
382 // back to UnresolvedClass so that either verifier will be happy
383 // with the constant pool entry.
384 //
385 // this is an indirect CP entry so it needs special handling
386 case JVM_CONSTANT_Class:
387 case JVM_CONSTANT_UnresolvedClass:
388 {
389 int name_i = scratch_cp->klass_name_index_at(scratch_i);
390 int new_name_i = find_or_append_indirect_entry(scratch_cp, name_i, merge_cp_p,
391 merge_cp_length_p);
392
393 if (new_name_i != name_i) {
394 log_trace(redefine, class, constantpool)
395 ("Class entry@%d name_index change: %d to %d",
396 *merge_cp_length_p, name_i, new_name_i);
397 }
398
399 (*merge_cp_p)->temp_unresolved_klass_at_put(*merge_cp_length_p, new_name_i);
400 if (scratch_i != *merge_cp_length_p) {
401 // The new entry in *merge_cp_p is at a different index than
402 // the new entry in scratch_cp so we need to map the index values.
403 map_index(scratch_cp, scratch_i, *merge_cp_length_p);
404 }
405 (*merge_cp_length_p)++;
406 } break;
407
408 // these are direct CP entries so they can be directly appended,
409 // but double and long take two constant pool entries
410 case JVM_CONSTANT_Double: // fall through
411 case JVM_CONSTANT_Long:
412 {
413 ConstantPool::copy_entry_to(scratch_cp, scratch_i, *merge_cp_p, *merge_cp_length_p);
414
415 if (scratch_i != *merge_cp_length_p) {
416 // The new entry in *merge_cp_p is at a different index than
417 // the new entry in scratch_cp so we need to map the index values.
418 map_index(scratch_cp, scratch_i, *merge_cp_length_p);
419 }
420 (*merge_cp_length_p) += 2;
421 } break;
422
423 // these are direct CP entries so they can be directly appended
424 case JVM_CONSTANT_Float: // fall through
425 case JVM_CONSTANT_Integer: // fall through
426 case JVM_CONSTANT_Utf8: // fall through
427
428 // This was an indirect CP entry, but it has been changed into
429 // Symbol*s so this entry can be directly appended.
430 case JVM_CONSTANT_String: // fall through
431 {
432 ConstantPool::copy_entry_to(scratch_cp, scratch_i, *merge_cp_p, *merge_cp_length_p);
433
434 if (scratch_i != *merge_cp_length_p) {
435 // The new entry in *merge_cp_p is at a different index than
436 // the new entry in scratch_cp so we need to map the index values.
437 map_index(scratch_cp, scratch_i, *merge_cp_length_p);
438 }
439 (*merge_cp_length_p)++;
440 } break;
441
442 // this is an indirect CP entry so it needs special handling
443 case JVM_CONSTANT_NameAndType:
444 {
445 int name_ref_i = scratch_cp->name_ref_index_at(scratch_i);
446 int new_name_ref_i = find_or_append_indirect_entry(scratch_cp, name_ref_i, merge_cp_p,
447 merge_cp_length_p);
448
449 int signature_ref_i = scratch_cp->signature_ref_index_at(scratch_i);
450 int new_signature_ref_i = find_or_append_indirect_entry(scratch_cp, signature_ref_i,
451 merge_cp_p, merge_cp_length_p);
452
453 // If the referenced entries already exist in *merge_cp_p, then
454 // both new_name_ref_i and new_signature_ref_i will both be 0.
455 // In that case, all we are appending is the current entry.
456 if (new_name_ref_i != name_ref_i) {
457 log_trace(redefine, class, constantpool)
458 ("NameAndType entry@%d name_ref_index change: %d to %d",
459 *merge_cp_length_p, name_ref_i, new_name_ref_i);
460 }
461 if (new_signature_ref_i != signature_ref_i) {
462 log_trace(redefine, class, constantpool)
463 ("NameAndType entry@%d signature_ref_index change: %d to %d",
464 *merge_cp_length_p, signature_ref_i, new_signature_ref_i);
465 }
466
467 (*merge_cp_p)->name_and_type_at_put(*merge_cp_length_p,
468 new_name_ref_i, new_signature_ref_i);
469 if (scratch_i != *merge_cp_length_p) {
470 // The new entry in *merge_cp_p is at a different index than
471 // the new entry in scratch_cp so we need to map the index values.
472 map_index(scratch_cp, scratch_i, *merge_cp_length_p);
473 }
474 (*merge_cp_length_p)++;
475 } break;
476
477 // this is a double-indirect CP entry so it needs special handling
478 case JVM_CONSTANT_Fieldref: // fall through
479 case JVM_CONSTANT_InterfaceMethodref: // fall through
480 case JVM_CONSTANT_Methodref:
481 {
482 int klass_ref_i = scratch_cp->uncached_klass_ref_index_at(scratch_i);
483 int new_klass_ref_i = find_or_append_indirect_entry(scratch_cp, klass_ref_i,
484 merge_cp_p, merge_cp_length_p);
485
486 int name_and_type_ref_i = scratch_cp->uncached_name_and_type_ref_index_at(scratch_i);
487 int new_name_and_type_ref_i = find_or_append_indirect_entry(scratch_cp, name_and_type_ref_i,
488 merge_cp_p, merge_cp_length_p);
489
490 const char *entry_name = nullptr;
491 switch (scratch_cp->tag_at(scratch_i).value()) {
492 case JVM_CONSTANT_Fieldref:
493 entry_name = "Fieldref";
494 (*merge_cp_p)->field_at_put(*merge_cp_length_p, new_klass_ref_i,
495 new_name_and_type_ref_i);
496 break;
497 case JVM_CONSTANT_InterfaceMethodref:
498 entry_name = "IFMethodref";
499 (*merge_cp_p)->interface_method_at_put(*merge_cp_length_p,
500 new_klass_ref_i, new_name_and_type_ref_i);
501 break;
502 case JVM_CONSTANT_Methodref:
503 entry_name = "Methodref";
504 (*merge_cp_p)->method_at_put(*merge_cp_length_p, new_klass_ref_i,
505 new_name_and_type_ref_i);
506 break;
507 default:
508 guarantee(false, "bad switch");
509 break;
510 }
511
512 if (klass_ref_i != new_klass_ref_i) {
513 log_trace(redefine, class, constantpool)
514 ("%s entry@%d class_index changed: %d to %d", entry_name, *merge_cp_length_p, klass_ref_i, new_klass_ref_i);
515 }
516 if (name_and_type_ref_i != new_name_and_type_ref_i) {
517 log_trace(redefine, class, constantpool)
518 ("%s entry@%d name_and_type_index changed: %d to %d",
519 entry_name, *merge_cp_length_p, name_and_type_ref_i, new_name_and_type_ref_i);
520 }
521
522 if (scratch_i != *merge_cp_length_p) {
523 // The new entry in *merge_cp_p is at a different index than
524 // the new entry in scratch_cp so we need to map the index values.
525 map_index(scratch_cp, scratch_i, *merge_cp_length_p);
526 }
527 (*merge_cp_length_p)++;
528 } break;
529
530 // this is an indirect CP entry so it needs special handling
531 case JVM_CONSTANT_MethodType:
532 {
533 int ref_i = scratch_cp->method_type_index_at(scratch_i);
534 int new_ref_i = find_or_append_indirect_entry(scratch_cp, ref_i, merge_cp_p,
535 merge_cp_length_p);
536 if (new_ref_i != ref_i) {
537 log_trace(redefine, class, constantpool)
538 ("MethodType entry@%d ref_index change: %d to %d", *merge_cp_length_p, ref_i, new_ref_i);
539 }
540 (*merge_cp_p)->method_type_index_at_put(*merge_cp_length_p, new_ref_i);
541 if (scratch_i != *merge_cp_length_p) {
542 // The new entry in *merge_cp_p is at a different index than
543 // the new entry in scratch_cp so we need to map the index values.
544 map_index(scratch_cp, scratch_i, *merge_cp_length_p);
545 }
546 (*merge_cp_length_p)++;
547 } break;
548
549 // this is an indirect CP entry so it needs special handling
550 case JVM_CONSTANT_MethodHandle:
551 {
552 int ref_kind = scratch_cp->method_handle_ref_kind_at(scratch_i);
553 int ref_i = scratch_cp->method_handle_index_at(scratch_i);
554 int new_ref_i = find_or_append_indirect_entry(scratch_cp, ref_i, merge_cp_p,
555 merge_cp_length_p);
556 if (new_ref_i != ref_i) {
557 log_trace(redefine, class, constantpool)
558 ("MethodHandle entry@%d ref_index change: %d to %d", *merge_cp_length_p, ref_i, new_ref_i);
559 }
560 (*merge_cp_p)->method_handle_index_at_put(*merge_cp_length_p, ref_kind, new_ref_i);
561 if (scratch_i != *merge_cp_length_p) {
562 // The new entry in *merge_cp_p is at a different index than
563 // the new entry in scratch_cp so we need to map the index values.
564 map_index(scratch_cp, scratch_i, *merge_cp_length_p);
565 }
566 (*merge_cp_length_p)++;
567 } break;
568
569 // this is an indirect CP entry so it needs special handling
570 case JVM_CONSTANT_Dynamic: // fall through
571 case JVM_CONSTANT_InvokeDynamic:
572 {
573 // Index of the bootstrap specifier in the operands array
574 int old_bs_i = scratch_cp->bootstrap_methods_attribute_index(scratch_i);
575 int new_bs_i = find_or_append_operand(scratch_cp, old_bs_i, merge_cp_p,
576 merge_cp_length_p);
577 // The bootstrap method NameAndType_info index
578 int old_ref_i = scratch_cp->bootstrap_name_and_type_ref_index_at(scratch_i);
579 int new_ref_i = find_or_append_indirect_entry(scratch_cp, old_ref_i, merge_cp_p,
580 merge_cp_length_p);
581 if (new_bs_i != old_bs_i) {
582 log_trace(redefine, class, constantpool)
583 ("Dynamic entry@%d bootstrap_method_attr_index change: %d to %d",
584 *merge_cp_length_p, old_bs_i, new_bs_i);
585 }
586 if (new_ref_i != old_ref_i) {
587 log_trace(redefine, class, constantpool)
588 ("Dynamic entry@%d name_and_type_index change: %d to %d", *merge_cp_length_p, old_ref_i, new_ref_i);
589 }
590
591 if (scratch_cp->tag_at(scratch_i).is_dynamic_constant())
592 (*merge_cp_p)->dynamic_constant_at_put(*merge_cp_length_p, new_bs_i, new_ref_i);
593 else
594 (*merge_cp_p)->invoke_dynamic_at_put(*merge_cp_length_p, new_bs_i, new_ref_i);
595 if (scratch_i != *merge_cp_length_p) {
596 // The new entry in *merge_cp_p is at a different index than
597 // the new entry in scratch_cp so we need to map the index values.
598 map_index(scratch_cp, scratch_i, *merge_cp_length_p);
599 }
600 (*merge_cp_length_p)++;
601 } break;
602
603 // At this stage, Class or UnresolvedClass could be in scratch_cp, but not
604 // ClassIndex
605 case JVM_CONSTANT_ClassIndex: // fall through
606
607 // Invalid is used as the tag for the second constant pool entry
608 // occupied by JVM_CONSTANT_Double or JVM_CONSTANT_Long. It should
609 // not be seen by itself.
610 case JVM_CONSTANT_Invalid: // fall through
611
612 // At this stage, String could be here, but not StringIndex
613 case JVM_CONSTANT_StringIndex: // fall through
614
615 // At this stage JVM_CONSTANT_UnresolvedClassInError should not be here
616 case JVM_CONSTANT_UnresolvedClassInError: // fall through
617
618 default:
619 {
620 // leave a breadcrumb
621 jbyte bad_value = scratch_cp->tag_at(scratch_i).value();
622 ShouldNotReachHere();
623 } break;
624 } // end switch tag value
625 } // end append_entry()
626
627
628 u2 VM_RedefineClasses::find_or_append_indirect_entry(const constantPoolHandle& scratch_cp,
629 int ref_i, constantPoolHandle *merge_cp_p, int *merge_cp_length_p) {
630
631 int new_ref_i = ref_i;
632 bool match = (ref_i < *merge_cp_length_p) &&
633 scratch_cp->compare_entry_to(ref_i, *merge_cp_p, ref_i);
634
635 if (!match) {
636 // forward reference in *merge_cp_p or not a direct match
637 int found_i = scratch_cp->find_matching_entry(ref_i, *merge_cp_p);
638 if (found_i != 0) {
639 guarantee(found_i != ref_i, "compare_entry_to() and find_matching_entry() do not agree");
640 // Found a matching entry somewhere else in *merge_cp_p so just need a mapping entry.
641 new_ref_i = found_i;
642 map_index(scratch_cp, ref_i, found_i);
643 } else {
644 // no match found so we have to append this entry to *merge_cp_p
645 append_entry(scratch_cp, ref_i, merge_cp_p, merge_cp_length_p);
646 // The above call to append_entry() can only append one entry
647 // so the post call query of *merge_cp_length_p is only for
648 // the sake of consistency.
649 new_ref_i = *merge_cp_length_p - 1;
650 }
651 }
652
653 // constant pool indices are u2, unless the merged constant pool overflows which
654 // we don't check for.
655 return checked_cast<u2>(new_ref_i);
656 } // end find_or_append_indirect_entry()
657
658
659 // Append a bootstrap specifier into the merge_cp operands that is semantically equal
660 // to the scratch_cp operands bootstrap specifier passed by the old_bs_i index.
661 // Recursively append new merge_cp entries referenced by the new bootstrap specifier.
662 void VM_RedefineClasses::append_operand(const constantPoolHandle& scratch_cp, const int old_bs_i,
663 constantPoolHandle *merge_cp_p, int *merge_cp_length_p) {
664
665 BSMAttributeEntry* old_bsme = scratch_cp->bsm_attribute_entry(old_bs_i);
666 u2 old_ref_i = old_bsme->bootstrap_method_index();
667 u2 new_ref_i = find_or_append_indirect_entry(scratch_cp, old_ref_i, merge_cp_p,
668 merge_cp_length_p);
669 if (new_ref_i != old_ref_i) {
670 log_trace(redefine, class, constantpool)
671 ("operands entry@%d bootstrap method ref_index change: %d to %d", _operands_cur_length, old_ref_i, new_ref_i);
672 }
673
674 Array<u2>* merge_ops = (*merge_cp_p)->operands();
675 int new_bs_i = _operands_cur_length;
676 // We have _operands_cur_length == 0 when the merge_cp operands is empty yet.
677 // However, the operand_offset_at(0) was set in the extend_operands() call.
678 int new_base = (new_bs_i == 0) ? (*merge_cp_p)->operand_offset_at(0)
679 : (*merge_cp_p)->operand_next_offset_at(new_bs_i - 1);
680 u2 argc = old_bsme->argument_count();
681
682 ConstantPool::operand_offset_at_put(merge_ops, _operands_cur_length, new_base);
683 merge_ops->at_put(new_base++, new_ref_i);
684 merge_ops->at_put(new_base++, argc);
685
686 for (int i = 0; i < argc; i++) {
687 u2 old_arg_ref_i = old_bsme->argument_index(i);
688 u2 new_arg_ref_i = find_or_append_indirect_entry(scratch_cp, old_arg_ref_i, merge_cp_p,
689 merge_cp_length_p);
690 merge_ops->at_put(new_base++, new_arg_ref_i);
691 if (new_arg_ref_i != old_arg_ref_i) {
692 log_trace(redefine, class, constantpool)
693 ("operands entry@%d bootstrap method argument ref_index change: %d to %d",
694 _operands_cur_length, old_arg_ref_i, new_arg_ref_i);
695 }
696 }
697 if (old_bs_i != _operands_cur_length) {
698 // The bootstrap specifier in *merge_cp_p is at a different index than
699 // that in scratch_cp so we need to map the index values.
700 map_operand_index(old_bs_i, new_bs_i);
701 }
702 _operands_cur_length++;
703 } // end append_operand()
704
705
706 int VM_RedefineClasses::find_or_append_operand(const constantPoolHandle& scratch_cp,
707 int old_bs_i, constantPoolHandle *merge_cp_p, int *merge_cp_length_p) {
708
709 int new_bs_i = old_bs_i; // bootstrap specifier index
710 bool match = (old_bs_i < _operands_cur_length) &&
711 scratch_cp->compare_operand_to(old_bs_i, *merge_cp_p, old_bs_i);
712
713 if (!match) {
714 // forward reference in *merge_cp_p or not a direct match
715 int found_i = scratch_cp->find_matching_operand(old_bs_i, *merge_cp_p,
716 _operands_cur_length);
717 if (found_i != -1) {
718 guarantee(found_i != old_bs_i, "compare_operand_to() and find_matching_operand() disagree");
719 // found a matching operand somewhere else in *merge_cp_p so just need a mapping
720 new_bs_i = found_i;
721 map_operand_index(old_bs_i, found_i);
722 } else {
723 // no match found so we have to append this bootstrap specifier to *merge_cp_p
724 append_operand(scratch_cp, old_bs_i, merge_cp_p, merge_cp_length_p);
725 new_bs_i = _operands_cur_length - 1;
726 }
727 }
728 return new_bs_i;
729 } // end find_or_append_operand()
730
731
732 void VM_RedefineClasses::finalize_operands_merge(const constantPoolHandle& merge_cp, TRAPS) {
733 if (merge_cp->operands() == nullptr) {
734 return;
735 }
736 // Shrink the merge_cp operands
737 merge_cp->shrink_operands(_operands_cur_length, CHECK);
738
739 if (log_is_enabled(Trace, redefine, class, constantpool)) {
740 // don't want to loop unless we are tracing
741 int count = 0;
742 for (int i = 1; i < _operands_index_map_p->length(); i++) {
743 int value = _operands_index_map_p->at(i);
744 if (value != -1) {
745 log_trace(redefine, class, constantpool)("operands_index_map[%d]: old=%d new=%d", count, i, value);
746 count++;
747 }
748 }
749 }
750 // Clean-up
751 _operands_index_map_p = nullptr;
752 _operands_cur_length = 0;
753 _operands_index_map_count = 0;
754 } // end finalize_operands_merge()
755
756 // Symbol* comparator for qsort
757 // The caller must have an active ResourceMark.
758 static int symcmp(const void* a, const void* b) {
759 char* astr = (*(Symbol**)a)->as_C_string();
760 char* bstr = (*(Symbol**)b)->as_C_string();
761 return strcmp(astr, bstr);
762 }
763
764 // The caller must have an active ResourceMark.
765 static jvmtiError check_attribute_arrays(const char* attr_name,
766 InstanceKlass* the_class, InstanceKlass* scratch_class,
767 Array<u2>* the_array, Array<u2>* scr_array) {
768 bool the_array_exists = the_array != Universe::the_empty_short_array();
769 bool scr_array_exists = scr_array != Universe::the_empty_short_array();
770
771 int array_len = the_array->length();
772 if (the_array_exists && scr_array_exists) {
773 if (array_len != scr_array->length()) {
774 log_trace(redefine, class)
775 ("redefined class %s attribute change error: %s len=%d changed to len=%d",
776 the_class->external_name(), attr_name, array_len, scr_array->length());
777 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_CLASS_ATTRIBUTE_CHANGED;
778 }
779
780 // The order of entries in the attribute array is not specified so we
781 // have to explicitly check for the same contents. We do this by copying
782 // the referenced symbols into their own arrays, sorting them and then
783 // comparing each element pair.
784
785 Symbol** the_syms = NEW_RESOURCE_ARRAY_RETURN_NULL(Symbol*, array_len);
786 Symbol** scr_syms = NEW_RESOURCE_ARRAY_RETURN_NULL(Symbol*, array_len);
787
788 if (the_syms == nullptr || scr_syms == nullptr) {
789 return JVMTI_ERROR_OUT_OF_MEMORY;
790 }
791
792 for (int i = 0; i < array_len; i++) {
793 int the_cp_index = the_array->at(i);
794 int scr_cp_index = scr_array->at(i);
795 the_syms[i] = the_class->constants()->klass_name_at(the_cp_index);
796 scr_syms[i] = scratch_class->constants()->klass_name_at(scr_cp_index);
797 }
798
799 qsort(the_syms, array_len, sizeof(Symbol*), symcmp);
800 qsort(scr_syms, array_len, sizeof(Symbol*), symcmp);
801
802 for (int i = 0; i < array_len; i++) {
803 if (the_syms[i] != scr_syms[i]) {
804 log_info(redefine, class)
805 ("redefined class %s attribute change error: %s[%d]: %s changed to %s",
806 the_class->external_name(), attr_name, i,
807 the_syms[i]->as_C_string(), scr_syms[i]->as_C_string());
808 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_CLASS_ATTRIBUTE_CHANGED;
809 }
810 }
811 } else if (the_array_exists ^ scr_array_exists) {
812 const char* action_str = (the_array_exists) ? "removed" : "added";
813 log_info(redefine, class)
814 ("redefined class %s attribute change error: %s attribute %s",
815 the_class->external_name(), attr_name, action_str);
816 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_CLASS_ATTRIBUTE_CHANGED;
817 }
818 return JVMTI_ERROR_NONE;
819 }
820
821 static jvmtiError check_nest_attributes(InstanceKlass* the_class,
822 InstanceKlass* scratch_class) {
823 // Check whether the class NestHost attribute has been changed.
824 Thread* thread = Thread::current();
825 ResourceMark rm(thread);
826 u2 the_nest_host_idx = the_class->nest_host_index();
827 u2 scr_nest_host_idx = scratch_class->nest_host_index();
828
829 if (the_nest_host_idx != 0 && scr_nest_host_idx != 0) {
830 Symbol* the_sym = the_class->constants()->klass_name_at(the_nest_host_idx);
831 Symbol* scr_sym = scratch_class->constants()->klass_name_at(scr_nest_host_idx);
832 if (the_sym != scr_sym) {
833 log_info(redefine, class, nestmates)
834 ("redefined class %s attribute change error: NestHost class: %s replaced with: %s",
835 the_class->external_name(), the_sym->as_C_string(), scr_sym->as_C_string());
836 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_CLASS_ATTRIBUTE_CHANGED;
837 }
838 } else if ((the_nest_host_idx == 0) ^ (scr_nest_host_idx == 0)) {
839 const char* action_str = (the_nest_host_idx != 0) ? "removed" : "added";
840 log_info(redefine, class, nestmates)
841 ("redefined class %s attribute change error: NestHost attribute %s",
842 the_class->external_name(), action_str);
843 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_CLASS_ATTRIBUTE_CHANGED;
844 }
845
846 // Check whether the class NestMembers attribute has been changed.
847 return check_attribute_arrays("NestMembers",
848 the_class, scratch_class,
849 the_class->nest_members(),
850 scratch_class->nest_members());
851 }
852
853 // Return an error status if the class Record attribute was changed.
854 static jvmtiError check_record_attribute(InstanceKlass* the_class, InstanceKlass* scratch_class) {
855 // Get lists of record components.
856 Array<RecordComponent*>* the_record = the_class->record_components();
857 Array<RecordComponent*>* scr_record = scratch_class->record_components();
858 bool the_record_exists = the_record != nullptr;
859 bool scr_record_exists = scr_record != nullptr;
860
861 if (the_record_exists && scr_record_exists) {
862 int the_num_components = the_record->length();
863 int scr_num_components = scr_record->length();
864 if (the_num_components != scr_num_components) {
865 log_info(redefine, class, record)
866 ("redefined class %s attribute change error: Record num_components=%d changed to num_components=%d",
867 the_class->external_name(), the_num_components, scr_num_components);
868 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_CLASS_ATTRIBUTE_CHANGED;
869 }
870
871 // Compare each field in each record component.
872 ConstantPool* the_cp = the_class->constants();
873 ConstantPool* scr_cp = scratch_class->constants();
874 for (int x = 0; x < the_num_components; x++) {
875 RecordComponent* the_component = the_record->at(x);
876 RecordComponent* scr_component = scr_record->at(x);
877 const Symbol* const the_name = the_cp->symbol_at(the_component->name_index());
878 const Symbol* const scr_name = scr_cp->symbol_at(scr_component->name_index());
879 const Symbol* const the_descr = the_cp->symbol_at(the_component->descriptor_index());
880 const Symbol* const scr_descr = scr_cp->symbol_at(scr_component->descriptor_index());
881 if (the_name != scr_name || the_descr != scr_descr) {
882 log_info(redefine, class, record)
883 ("redefined class %s attribute change error: Record name_index, descriptor_index, and/or attributes_count changed",
884 the_class->external_name());
885 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_CLASS_ATTRIBUTE_CHANGED;
886 }
887
888 int the_gen_sig = the_component->generic_signature_index();
889 int scr_gen_sig = scr_component->generic_signature_index();
890 const Symbol* const the_gen_sig_sym = (the_gen_sig == 0 ? nullptr :
891 the_cp->symbol_at(the_component->generic_signature_index()));
892 const Symbol* const scr_gen_sig_sym = (scr_gen_sig == 0 ? nullptr :
893 scr_cp->symbol_at(scr_component->generic_signature_index()));
894 if (the_gen_sig_sym != scr_gen_sig_sym) {
895 log_info(redefine, class, record)
896 ("redefined class %s attribute change error: Record generic_signature attribute changed",
897 the_class->external_name());
898 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_CLASS_ATTRIBUTE_CHANGED;
899 }
900
901 // It's okay if a record component's annotations were changed.
902 }
903
904 } else if (the_record_exists ^ scr_record_exists) {
905 const char* action_str = (the_record_exists) ? "removed" : "added";
906 log_info(redefine, class, record)
907 ("redefined class %s attribute change error: Record attribute %s",
908 the_class->external_name(), action_str);
909 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_CLASS_ATTRIBUTE_CHANGED;
910 }
911
912 return JVMTI_ERROR_NONE;
913 }
914
915
916 static jvmtiError check_permitted_subclasses_attribute(InstanceKlass* the_class,
917 InstanceKlass* scratch_class) {
918 Thread* thread = Thread::current();
919 ResourceMark rm(thread);
920
921 // Check whether the class PermittedSubclasses attribute has been changed.
922 return check_attribute_arrays("PermittedSubclasses",
923 the_class, scratch_class,
924 the_class->permitted_subclasses(),
925 scratch_class->permitted_subclasses());
926 }
927
928 static bool can_add_or_delete(Method* m) {
929 // Compatibility mode
930 return (AllowRedefinitionToAddDeleteMethods &&
931 (m->is_private() && (m->is_static() || m->is_final())));
932 }
933
934 jvmtiError VM_RedefineClasses::compare_and_normalize_class_versions(
935 InstanceKlass* the_class,
936 InstanceKlass* scratch_class) {
937 int i;
938
939 // Check superclasses, or rather their names, since superclasses themselves can be
940 // requested to replace.
941 // Check for null superclass first since this might be java.lang.Object
942 if (the_class->super() != scratch_class->super() &&
943 (the_class->super() == nullptr || scratch_class->super() == nullptr ||
944 the_class->super()->name() !=
945 scratch_class->super()->name())) {
946 log_info(redefine, class, normalize)
947 ("redefined class %s superclass change error: superclass changed from %s to %s.",
948 the_class->external_name(),
949 the_class->super() == nullptr ? "null" : the_class->super()->external_name(),
950 scratch_class->super() == nullptr ? "null" : scratch_class->super()->external_name());
951 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_HIERARCHY_CHANGED;
952 }
953
954 // Check if the number, names and order of directly implemented interfaces are the same.
955 // I think in principle we should just check if the sets of names of directly implemented
956 // interfaces are the same, i.e. the order of declaration (which, however, if changed in the
957 // .java file, also changes in .class file) should not matter. However, comparing sets is
958 // technically a bit more difficult, and, more importantly, I am not sure at present that the
959 // order of interfaces does not matter on the implementation level, i.e. that the VM does not
960 // rely on it somewhere.
961 Array<InstanceKlass*>* k_interfaces = the_class->local_interfaces();
962 Array<InstanceKlass*>* k_new_interfaces = scratch_class->local_interfaces();
963 int n_intfs = k_interfaces->length();
964 if (n_intfs != k_new_interfaces->length()) {
965 log_info(redefine, class, normalize)
966 ("redefined class %s interfaces change error: number of implemented interfaces changed from %d to %d.",
967 the_class->external_name(), n_intfs, k_new_interfaces->length());
968 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_HIERARCHY_CHANGED;
969 }
970 for (i = 0; i < n_intfs; i++) {
971 if (k_interfaces->at(i)->name() !=
972 k_new_interfaces->at(i)->name()) {
973 log_info(redefine, class, normalize)
974 ("redefined class %s interfaces change error: interface changed from %s to %s.",
975 the_class->external_name(),
976 k_interfaces->at(i)->external_name(), k_new_interfaces->at(i)->external_name());
977 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_HIERARCHY_CHANGED;
978 }
979 }
980
981 // Check whether class is in the error init state.
982 if (the_class->is_in_error_state()) {
983 log_info(redefine, class, normalize)
984 ("redefined class %s is in error init state.", the_class->external_name());
985 // TBD #5057930: special error code is needed in 1.6
986 return JVMTI_ERROR_INVALID_CLASS;
987 }
988
989 // Check whether the nest-related attributes have been changed.
990 jvmtiError err = check_nest_attributes(the_class, scratch_class);
991 if (err != JVMTI_ERROR_NONE) {
992 return err;
993 }
994
995 // Check whether the Record attribute has been changed.
996 err = check_record_attribute(the_class, scratch_class);
997 if (err != JVMTI_ERROR_NONE) {
998 return err;
999 }
1000
1001 // Check whether the PermittedSubclasses attribute has been changed.
1002 err = check_permitted_subclasses_attribute(the_class, scratch_class);
1003 if (err != JVMTI_ERROR_NONE) {
1004 return err;
1005 }
1006
1007 // Check whether class modifiers are the same.
1008 u2 old_flags = the_class->access_flags().as_class_flags();
1009 u2 new_flags = scratch_class->access_flags().as_class_flags();
1010 if (old_flags != new_flags) {
1011 log_info(redefine, class, normalize)
1012 ("redefined class %s modifiers change error: modifiers changed from %d to %d.",
1013 the_class->external_name(), old_flags, new_flags);
1014 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_CLASS_MODIFIERS_CHANGED;
1015 }
1016
1017 // Check if the number, names, types and order of fields declared in these classes
1018 // are the same.
1019 JavaFieldStream old_fs(the_class);
1020 JavaFieldStream new_fs(scratch_class);
1021 for (; !old_fs.done() && !new_fs.done(); old_fs.next(), new_fs.next()) {
1022 // name and signature
1023 Symbol* name_sym1 = the_class->constants()->symbol_at(old_fs.name_index());
1024 Symbol* sig_sym1 = the_class->constants()->symbol_at(old_fs.signature_index());
1025 Symbol* name_sym2 = scratch_class->constants()->symbol_at(new_fs.name_index());
1026 Symbol* sig_sym2 = scratch_class->constants()->symbol_at(new_fs.signature_index());
1027 if (name_sym1 != name_sym2 || sig_sym1 != sig_sym2) {
1028 log_info(redefine, class, normalize)
1029 ("redefined class %s fields change error: field %s %s changed to %s %s.",
1030 the_class->external_name(),
1031 sig_sym1->as_C_string(), name_sym1->as_C_string(),
1032 sig_sym2->as_C_string(), name_sym2->as_C_string());
1033 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_SCHEMA_CHANGED;
1034 }
1035 // offset
1036 if (old_fs.offset() != new_fs.offset()) {
1037 log_info(redefine, class, normalize)
1038 ("redefined class %s field %s change error: offset changed from %d to %d.",
1039 the_class->external_name(), name_sym2->as_C_string(), old_fs.offset(), new_fs.offset());
1040 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_SCHEMA_CHANGED;
1041 }
1042 // access
1043 old_flags = old_fs.access_flags().as_field_flags();
1044 new_flags = new_fs.access_flags().as_field_flags();
1045 if (old_flags != new_flags) {
1046 log_info(redefine, class, normalize)
1047 ("redefined class %s field %s change error: modifiers changed from %d to %d.",
1048 the_class->external_name(), name_sym2->as_C_string(), old_flags, new_flags);
1049 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_SCHEMA_CHANGED;
1050 }
1051 }
1052
1053 // If both streams aren't done then we have a differing number of
1054 // fields.
1055 if (!old_fs.done() || !new_fs.done()) {
1056 const char* action = old_fs.done() ? "added" : "deleted";
1057 log_info(redefine, class, normalize)
1058 ("redefined class %s fields change error: some fields were %s.",
1059 the_class->external_name(), action);
1060 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_SCHEMA_CHANGED;
1061 }
1062
1063 // Do a parallel walk through the old and new methods. Detect
1064 // cases where they match (exist in both), have been added in
1065 // the new methods, or have been deleted (exist only in the
1066 // old methods). The class file parser places methods in order
1067 // by method name, but does not order overloaded methods by
1068 // signature. In order to determine what fate befell the methods,
1069 // this code places the overloaded new methods that have matching
1070 // old methods in the same order as the old methods and places
1071 // new overloaded methods at the end of overloaded methods of
1072 // that name. The code for this order normalization is adapted
1073 // from the algorithm used in InstanceKlass::find_method().
1074 // Since we are swapping out of order entries as we find them,
1075 // we only have to search forward through the overloaded methods.
1076 // Methods which are added and have the same name as an existing
1077 // method (but different signature) will be put at the end of
1078 // the methods with that name, and the name mismatch code will
1079 // handle them.
1080 Array<Method*>* k_old_methods(the_class->methods());
1081 Array<Method*>* k_new_methods(scratch_class->methods());
1082 int n_old_methods = k_old_methods->length();
1083 int n_new_methods = k_new_methods->length();
1084 Thread* thread = Thread::current();
1085
1086 int ni = 0;
1087 int oi = 0;
1088 while (true) {
1089 Method* k_old_method;
1090 Method* k_new_method;
1091 enum { matched, added, deleted, undetermined } method_was = undetermined;
1092
1093 if (oi >= n_old_methods) {
1094 if (ni >= n_new_methods) {
1095 break; // we've looked at everything, done
1096 }
1097 // New method at the end
1098 k_new_method = k_new_methods->at(ni);
1099 method_was = added;
1100 } else if (ni >= n_new_methods) {
1101 // Old method, at the end, is deleted
1102 k_old_method = k_old_methods->at(oi);
1103 method_was = deleted;
1104 } else {
1105 // There are more methods in both the old and new lists
1106 k_old_method = k_old_methods->at(oi);
1107 k_new_method = k_new_methods->at(ni);
1108 if (k_old_method->name() != k_new_method->name()) {
1109 // Methods are sorted by method name, so a mismatch means added
1110 // or deleted
1111 if (k_old_method->name()->fast_compare(k_new_method->name()) > 0) {
1112 method_was = added;
1113 } else {
1114 method_was = deleted;
1115 }
1116 } else if (k_old_method->signature() == k_new_method->signature()) {
1117 // Both the name and signature match
1118 method_was = matched;
1119 } else {
1120 // The name matches, but the signature doesn't, which means we have to
1121 // search forward through the new overloaded methods.
1122 int nj; // outside the loop for post-loop check
1123 for (nj = ni + 1; nj < n_new_methods; nj++) {
1124 Method* m = k_new_methods->at(nj);
1125 if (k_old_method->name() != m->name()) {
1126 // reached another method name so no more overloaded methods
1127 method_was = deleted;
1128 break;
1129 }
1130 if (k_old_method->signature() == m->signature()) {
1131 // found a match so swap the methods
1132 k_new_methods->at_put(ni, m);
1133 k_new_methods->at_put(nj, k_new_method);
1134 k_new_method = m;
1135 method_was = matched;
1136 break;
1137 }
1138 }
1139
1140 if (nj >= n_new_methods) {
1141 // reached the end without a match; so method was deleted
1142 method_was = deleted;
1143 }
1144 }
1145 }
1146
1147 switch (method_was) {
1148 case matched:
1149 // methods match, be sure modifiers do too
1150 old_flags = k_old_method->access_flags().as_method_flags();
1151 new_flags = k_new_method->access_flags().as_method_flags();
1152 if ((old_flags ^ new_flags) & ~(JVM_ACC_NATIVE)) {
1153 log_info(redefine, class, normalize)
1154 ("redefined class %s method %s modifiers error: modifiers changed from %d to %d",
1155 the_class->external_name(), k_old_method->name_and_sig_as_C_string(), old_flags, new_flags);
1156 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_METHOD_MODIFIERS_CHANGED;
1157 }
1158 {
1159 u2 new_num = k_new_method->method_idnum();
1160 u2 old_num = k_old_method->method_idnum();
1161 if (new_num != old_num) {
1162 Method* idnum_owner = scratch_class->method_with_idnum(old_num);
1163 if (idnum_owner != nullptr) {
1164 // There is already a method assigned this idnum -- switch them
1165 // Take current and original idnum from the new_method
1166 idnum_owner->set_method_idnum(new_num);
1167 idnum_owner->set_orig_method_idnum(k_new_method->orig_method_idnum());
1168 }
1169 // Take current and original idnum from the old_method
1170 k_new_method->set_method_idnum(old_num);
1171 k_new_method->set_orig_method_idnum(k_old_method->orig_method_idnum());
1172 if (thread->has_pending_exception()) {
1173 return JVMTI_ERROR_OUT_OF_MEMORY;
1174 }
1175 }
1176 }
1177 JFR_ONLY(k_new_method->copy_trace_flags(k_old_method->trace_flags());)
1178 log_trace(redefine, class, normalize)
1179 ("Method matched: new: %s [%d] == old: %s [%d]",
1180 k_new_method->name_and_sig_as_C_string(), ni, k_old_method->name_and_sig_as_C_string(), oi);
1181 // advance to next pair of methods
1182 ++oi;
1183 ++ni;
1184 break;
1185 case added:
1186 // method added, see if it is OK
1187 if (!can_add_or_delete(k_new_method)) {
1188 log_info(redefine, class, normalize)
1189 ("redefined class %s methods error: added method: %s [%d]",
1190 the_class->external_name(), k_new_method->name_and_sig_as_C_string(), ni);
1191 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_METHOD_ADDED;
1192 }
1193 {
1194 u2 num = the_class->next_method_idnum();
1195 if (num == ConstMethod::UNSET_IDNUM) {
1196 // cannot add any more methods
1197 log_info(redefine, class, normalize)
1198 ("redefined class %s methods error: can't create ID for new method %s [%d]",
1199 the_class->external_name(), k_new_method->name_and_sig_as_C_string(), ni);
1200 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_METHOD_ADDED;
1201 }
1202 u2 new_num = k_new_method->method_idnum();
1203 Method* idnum_owner = scratch_class->method_with_idnum(num);
1204 if (idnum_owner != nullptr) {
1205 // There is already a method assigned this idnum -- switch them
1206 // Take current and original idnum from the new_method
1207 idnum_owner->set_method_idnum(new_num);
1208 idnum_owner->set_orig_method_idnum(k_new_method->orig_method_idnum());
1209 }
1210 k_new_method->set_method_idnum(num);
1211 k_new_method->set_orig_method_idnum(num);
1212 if (thread->has_pending_exception()) {
1213 return JVMTI_ERROR_OUT_OF_MEMORY;
1214 }
1215 }
1216 log_trace(redefine, class, normalize)
1217 ("Method added: new: %s [%d]", k_new_method->name_and_sig_as_C_string(), ni);
1218 ++ni; // advance to next new method
1219 break;
1220 case deleted:
1221 // method deleted, see if it is OK
1222 if (!can_add_or_delete(k_old_method)) {
1223 log_info(redefine, class, normalize)
1224 ("redefined class %s methods error: deleted method %s [%d]",
1225 the_class->external_name(), k_old_method->name_and_sig_as_C_string(), oi);
1226 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_METHOD_DELETED;
1227 }
1228 log_trace(redefine, class, normalize)
1229 ("Method deleted: old: %s [%d]", k_old_method->name_and_sig_as_C_string(), oi);
1230 ++oi; // advance to next old method
1231 break;
1232 default:
1233 ShouldNotReachHere();
1234 }
1235 }
1236
1237 return JVMTI_ERROR_NONE;
1238 }
1239
1240
1241 // Find new constant pool index value for old constant pool index value
1242 // by searching the index map. Returns zero (0) if there is no mapped
1243 // value for the old constant pool index.
1244 u2 VM_RedefineClasses::find_new_index(int old_index) {
1245 if (_index_map_count == 0) {
1246 // map is empty so nothing can be found
1247 return 0;
1248 }
1249
1250 if (old_index < 1 || old_index >= _index_map_p->length()) {
1251 // The old_index is out of range so it is not mapped. This should
1252 // not happen in regular constant pool merging use, but it can
1253 // happen if a corrupt annotation is processed.
1254 return 0;
1255 }
1256
1257 int value = _index_map_p->at(old_index);
1258 if (value == -1) {
1259 // the old_index is not mapped
1260 return 0;
1261 }
1262
1263 // constant pool indices are u2, unless the merged constant pool overflows which
1264 // we don't check for.
1265 return checked_cast<u2>(value);
1266 } // end find_new_index()
1267
1268
1269 // Find new bootstrap specifier index value for old bootstrap specifier index
1270 // value by searching the index map. Returns unused index (-1) if there is
1271 // no mapped value for the old bootstrap specifier index.
1272 int VM_RedefineClasses::find_new_operand_index(int old_index) {
1273 if (_operands_index_map_count == 0) {
1274 // map is empty so nothing can be found
1275 return -1;
1276 }
1277
1278 if (old_index == -1 || old_index >= _operands_index_map_p->length()) {
1279 // The old_index is out of range so it is not mapped.
1280 // This should not happen in regular constant pool merging use.
1281 return -1;
1282 }
1283
1284 int value = _operands_index_map_p->at(old_index);
1285 if (value == -1) {
1286 // the old_index is not mapped
1287 return -1;
1288 }
1289
1290 return value;
1291 } // end find_new_operand_index()
1292
1293
1294 // The bug 6214132 caused the verification to fail.
1295 // 1. What's done in RedefineClasses() before verification:
1296 // a) A reference to the class being redefined (_the_class) and a
1297 // reference to new version of the class (_scratch_class) are
1298 // saved here for use during the bytecode verification phase of
1299 // RedefineClasses.
1300 // b) The _java_mirror field from _the_class is copied to the
1301 // _java_mirror field in _scratch_class. This means that a jclass
1302 // returned for _the_class or _scratch_class will refer to the
1303 // same Java mirror. The verifier will see the "one true mirror"
1304 // for the class being verified.
1305 // 2. See comments in JvmtiThreadState for what is done during verification.
1306
1307 class RedefineVerifyMark : public StackObj {
1308 private:
1309 JvmtiThreadState* _state;
1310 Klass* _scratch_class;
1311 OopHandle _scratch_mirror;
1312
1313 public:
1314
1315 RedefineVerifyMark(Klass* the_class, Klass* scratch_class,
1316 JvmtiThreadState* state) : _state(state), _scratch_class(scratch_class)
1317 {
1318 _state->set_class_versions_map(the_class, scratch_class);
1319 _scratch_mirror = the_class->java_mirror_handle(); // this is a copy that is swapped
1320 _scratch_class->swap_java_mirror_handle(_scratch_mirror);
1321 }
1322
1323 ~RedefineVerifyMark() {
1324 // Restore the scratch class's mirror, so when scratch_class is removed
1325 // the correct mirror pointing to it can be cleared.
1326 _scratch_class->swap_java_mirror_handle(_scratch_mirror);
1327 _state->clear_class_versions_map();
1328 }
1329 };
1330
1331
1332 jvmtiError VM_RedefineClasses::load_new_class_versions() {
1333
1334 // For consistency allocate memory using os::malloc wrapper.
1335 _scratch_classes = (InstanceKlass**)
1336 os::malloc(sizeof(InstanceKlass*) * _class_count, mtClass);
1337 if (_scratch_classes == nullptr) {
1338 return JVMTI_ERROR_OUT_OF_MEMORY;
1339 }
1340 // Zero initialize the _scratch_classes array.
1341 for (int i = 0; i < _class_count; i++) {
1342 _scratch_classes[i] = nullptr;
1343 }
1344
1345 JavaThread* current = JavaThread::current();
1346 ResourceMark rm(current);
1347
1348 JvmtiThreadState *state = JvmtiThreadState::state_for(current);
1349 // state can only be null if the current thread is exiting which
1350 // should not happen since we're trying to do a RedefineClasses
1351 guarantee(state != nullptr, "exiting thread calling load_new_class_versions");
1352 for (int i = 0; i < _class_count; i++) {
1353 // Create HandleMark so that any handles created while loading new class
1354 // versions are deleted. Constant pools are deallocated while merging
1355 // constant pools
1356 HandleMark hm(current);
1357 InstanceKlass* the_class = get_ik(_class_defs[i].klass);
1358
1359 log_debug(redefine, class, load)
1360 ("loading name=%s kind=%d (avail_mem=" UINT64_FORMAT "K)",
1361 the_class->external_name(), _class_load_kind, os::available_memory() >> 10);
1362
1363 ClassFileStream st((u1*)_class_defs[i].class_bytes,
1364 _class_defs[i].class_byte_count,
1365 "__VM_RedefineClasses__");
1366
1367 // Set redefined class handle in JvmtiThreadState class.
1368 // This redefined class is sent to agent event handler for class file
1369 // load hook event.
1370 state->set_class_being_redefined(the_class, _class_load_kind);
1371
1372 JavaThread* THREAD = current; // For exception macros.
1373 ExceptionMark em(THREAD);
1374 Handle protection_domain(THREAD, the_class->protection_domain());
1375 ClassLoadInfo cl_info(protection_domain);
1376 // Parse and create a class from the bytes, but this class isn't added
1377 // to the dictionary, so do not call resolve_from_stream.
1378 InstanceKlass* scratch_class = KlassFactory::create_from_stream(&st,
1379 the_class->name(),
1380 the_class->class_loader_data(),
1381 cl_info,
1382 THREAD);
1383
1384 // Clear class_being_redefined just to be sure.
1385 state->clear_class_being_redefined();
1386
1387 // TODO: if this is retransform, and nothing changed we can skip it
1388
1389 // Need to clean up allocated InstanceKlass if there's an error so assign
1390 // the result here. Caller deallocates all the scratch classes in case of
1391 // an error.
1392 _scratch_classes[i] = scratch_class;
1393
1394 if (HAS_PENDING_EXCEPTION) {
1395 Symbol* ex_name = PENDING_EXCEPTION->klass()->name();
1396 log_info(redefine, class, load, exceptions)("create_from_stream exception: '%s'", ex_name->as_C_string());
1397 CLEAR_PENDING_EXCEPTION;
1398
1399 if (ex_name == vmSymbols::java_lang_UnsupportedClassVersionError()) {
1400 return JVMTI_ERROR_UNSUPPORTED_VERSION;
1401 } else if (ex_name == vmSymbols::java_lang_ClassFormatError()) {
1402 return JVMTI_ERROR_INVALID_CLASS_FORMAT;
1403 } else if (ex_name == vmSymbols::java_lang_ClassCircularityError()) {
1404 return JVMTI_ERROR_CIRCULAR_CLASS_DEFINITION;
1405 } else if (ex_name == vmSymbols::java_lang_NoClassDefFoundError()) {
1406 // The message will be "XXX (wrong name: YYY)"
1407 return JVMTI_ERROR_NAMES_DONT_MATCH;
1408 } else if (ex_name == vmSymbols::java_lang_OutOfMemoryError()) {
1409 return JVMTI_ERROR_OUT_OF_MEMORY;
1410 } else { // Just in case more exceptions can be thrown..
1411 return JVMTI_ERROR_FAILS_VERIFICATION;
1412 }
1413 }
1414
1415 // Ensure class is linked before redefine
1416 if (!the_class->is_linked()) {
1417 the_class->link_class(THREAD);
1418 if (HAS_PENDING_EXCEPTION) {
1419 Symbol* ex_name = PENDING_EXCEPTION->klass()->name();
1420 oop message = java_lang_Throwable::message(PENDING_EXCEPTION);
1421 if (message != nullptr) {
1422 char* ex_msg = java_lang_String::as_utf8_string(message);
1423 log_info(redefine, class, load, exceptions)("link_class exception: '%s %s'",
1424 ex_name->as_C_string(), ex_msg);
1425 } else {
1426 log_info(redefine, class, load, exceptions)("link_class exception: '%s'",
1427 ex_name->as_C_string());
1428 }
1429 CLEAR_PENDING_EXCEPTION;
1430 if (ex_name == vmSymbols::java_lang_OutOfMemoryError()) {
1431 return JVMTI_ERROR_OUT_OF_MEMORY;
1432 } else if (ex_name == vmSymbols::java_lang_NoClassDefFoundError()) {
1433 return JVMTI_ERROR_INVALID_CLASS;
1434 } else {
1435 return JVMTI_ERROR_INTERNAL;
1436 }
1437 }
1438 }
1439
1440 // Do the validity checks in compare_and_normalize_class_versions()
1441 // before verifying the byte codes. By doing these checks first, we
1442 // limit the number of functions that require redirection from
1443 // the_class to scratch_class. In particular, we don't have to
1444 // modify JNI GetSuperclass() and thus won't change its performance.
1445 jvmtiError res = compare_and_normalize_class_versions(the_class,
1446 scratch_class);
1447 if (res != JVMTI_ERROR_NONE) {
1448 return res;
1449 }
1450
1451 // verify what the caller passed us
1452 {
1453 // The bug 6214132 caused the verification to fail.
1454 // Information about the_class and scratch_class is temporarily
1455 // recorded into jvmtiThreadState. This data is used to redirect
1456 // the_class to scratch_class in the JVM_* functions called by the
1457 // verifier. Please, refer to jvmtiThreadState.hpp for the detailed
1458 // description.
1459 RedefineVerifyMark rvm(the_class, scratch_class, state);
1460 Verifier::verify(scratch_class, true, THREAD);
1461 }
1462
1463 if (HAS_PENDING_EXCEPTION) {
1464 Symbol* ex_name = PENDING_EXCEPTION->klass()->name();
1465 log_info(redefine, class, load, exceptions)("verify_byte_codes exception: '%s'", ex_name->as_C_string());
1466 CLEAR_PENDING_EXCEPTION;
1467 if (ex_name == vmSymbols::java_lang_OutOfMemoryError()) {
1468 return JVMTI_ERROR_OUT_OF_MEMORY;
1469 } else {
1470 // tell the caller the bytecodes are bad
1471 return JVMTI_ERROR_FAILS_VERIFICATION;
1472 }
1473 }
1474
1475 res = merge_cp_and_rewrite(the_class, scratch_class, THREAD);
1476 if (HAS_PENDING_EXCEPTION) {
1477 Symbol* ex_name = PENDING_EXCEPTION->klass()->name();
1478 log_info(redefine, class, load, exceptions)("merge_cp_and_rewrite exception: '%s'", ex_name->as_C_string());
1479 CLEAR_PENDING_EXCEPTION;
1480 if (ex_name == vmSymbols::java_lang_OutOfMemoryError()) {
1481 return JVMTI_ERROR_OUT_OF_MEMORY;
1482 } else {
1483 return JVMTI_ERROR_INTERNAL;
1484 }
1485 }
1486
1487 #ifdef ASSERT
1488 {
1489 // verify what we have done during constant pool merging
1490 {
1491 RedefineVerifyMark rvm(the_class, scratch_class, state);
1492 Verifier::verify(scratch_class, true, THREAD);
1493 }
1494
1495 if (HAS_PENDING_EXCEPTION) {
1496 Symbol* ex_name = PENDING_EXCEPTION->klass()->name();
1497 log_info(redefine, class, load, exceptions)
1498 ("verify_byte_codes post merge-CP exception: '%s'", ex_name->as_C_string());
1499 CLEAR_PENDING_EXCEPTION;
1500 if (ex_name == vmSymbols::java_lang_OutOfMemoryError()) {
1501 return JVMTI_ERROR_OUT_OF_MEMORY;
1502 } else {
1503 // tell the caller that constant pool merging screwed up
1504 return JVMTI_ERROR_INTERNAL;
1505 }
1506 }
1507 }
1508 #endif // ASSERT
1509
1510 Rewriter::rewrite(scratch_class, THREAD);
1511 if (!HAS_PENDING_EXCEPTION) {
1512 scratch_class->link_methods(THREAD);
1513 }
1514 if (HAS_PENDING_EXCEPTION) {
1515 Symbol* ex_name = PENDING_EXCEPTION->klass()->name();
1516 log_info(redefine, class, load, exceptions)
1517 ("Rewriter::rewrite or link_methods exception: '%s'", ex_name->as_C_string());
1518 CLEAR_PENDING_EXCEPTION;
1519 if (ex_name == vmSymbols::java_lang_OutOfMemoryError()) {
1520 return JVMTI_ERROR_OUT_OF_MEMORY;
1521 } else {
1522 return JVMTI_ERROR_INTERNAL;
1523 }
1524 }
1525
1526 log_debug(redefine, class, load)
1527 ("loaded name=%s (avail_mem=" UINT64_FORMAT "K)", the_class->external_name(), os::available_memory() >> 10);
1528 }
1529
1530 return JVMTI_ERROR_NONE;
1531 }
1532
1533
1534 // Map old_index to new_index as needed. scratch_cp is only needed
1535 // for log calls.
1536 void VM_RedefineClasses::map_index(const constantPoolHandle& scratch_cp,
1537 int old_index, int new_index) {
1538 if (find_new_index(old_index) != 0) {
1539 // old_index is already mapped
1540 return;
1541 }
1542
1543 if (old_index == new_index) {
1544 // no mapping is needed
1545 return;
1546 }
1547
1548 _index_map_p->at_put(old_index, new_index);
1549 _index_map_count++;
1550
1551 log_trace(redefine, class, constantpool)
1552 ("mapped tag %d at index %d to %d", scratch_cp->tag_at(old_index).value(), old_index, new_index);
1553 } // end map_index()
1554
1555
1556 // Map old_index to new_index as needed.
1557 void VM_RedefineClasses::map_operand_index(int old_index, int new_index) {
1558 if (find_new_operand_index(old_index) != -1) {
1559 // old_index is already mapped
1560 return;
1561 }
1562
1563 if (old_index == new_index) {
1564 // no mapping is needed
1565 return;
1566 }
1567
1568 _operands_index_map_p->at_put(old_index, new_index);
1569 _operands_index_map_count++;
1570
1571 log_trace(redefine, class, constantpool)("mapped bootstrap specifier at index %d to %d", old_index, new_index);
1572 } // end map_index()
1573
1574
1575 // Merge old_cp and scratch_cp and return the results of the merge via
1576 // merge_cp_p. The number of entries in merge_cp_p is returned via
1577 // merge_cp_length_p. The entries in old_cp occupy the same locations
1578 // in merge_cp_p. Also creates a map of indices from entries in
1579 // scratch_cp to the corresponding entry in merge_cp_p. Index map
1580 // entries are only created for entries in scratch_cp that occupy a
1581 // different location in merged_cp_p.
1582 bool VM_RedefineClasses::merge_constant_pools(const constantPoolHandle& old_cp,
1583 const constantPoolHandle& scratch_cp, constantPoolHandle& merge_cp_p,
1584 int& merge_cp_length_p, TRAPS) {
1585
1586 // Worst case we need old_cp->length() + scratch_cp()->length(),
1587 // but the caller might be smart so make sure we have at least
1588 // the minimum.
1589 if (merge_cp_p->length() < old_cp->length()) {
1590 assert(false, "merge area too small");
1591 return false; // robustness
1592 }
1593
1594 log_info(redefine, class, constantpool)("old_cp_len=%d, scratch_cp_len=%d", old_cp->length(), scratch_cp->length());
1595
1596 {
1597 // Pass 0:
1598 // The old_cp is copied to *merge_cp_p; this means that any code
1599 // using old_cp does not have to change. This work looks like a
1600 // perfect fit for ConstantPool*::copy_cp_to(), but we need to
1601 // handle one special case:
1602 // - revert JVM_CONSTANT_Class to JVM_CONSTANT_UnresolvedClass
1603 // This will make verification happy.
1604
1605 int old_i; // index into old_cp
1606
1607 // index zero (0) is not used in constantPools
1608 for (old_i = 1; old_i < old_cp->length(); old_i++) {
1609 // leave debugging crumb
1610 jbyte old_tag = old_cp->tag_at(old_i).value();
1611 switch (old_tag) {
1612 case JVM_CONSTANT_Class:
1613 case JVM_CONSTANT_UnresolvedClass:
1614 // revert the copy to JVM_CONSTANT_UnresolvedClass
1615 // May be resolving while calling this so do the same for
1616 // JVM_CONSTANT_UnresolvedClass (klass_name_at() deals with transition)
1617 merge_cp_p->temp_unresolved_klass_at_put(old_i,
1618 old_cp->klass_name_index_at(old_i));
1619 break;
1620
1621 case JVM_CONSTANT_Double:
1622 case JVM_CONSTANT_Long:
1623 // just copy the entry to merge_cp_p, but double and long take
1624 // two constant pool entries
1625 ConstantPool::copy_entry_to(old_cp, old_i, merge_cp_p, old_i);
1626 old_i++;
1627 break;
1628
1629 default:
1630 // just copy the entry to merge_cp_p
1631 ConstantPool::copy_entry_to(old_cp, old_i, merge_cp_p, old_i);
1632 break;
1633 }
1634 } // end for each old_cp entry
1635
1636 ConstantPool::copy_operands(old_cp, merge_cp_p, CHECK_false);
1637 merge_cp_p->extend_operands(scratch_cp, CHECK_false);
1638
1639 // We don't need to sanity check that *merge_cp_length_p is within
1640 // *merge_cp_p bounds since we have the minimum on-entry check above.
1641 merge_cp_length_p = old_i;
1642 }
1643
1644 // merge_cp_len should be the same as old_cp->length() at this point
1645 // so this trace message is really a "warm-and-breathing" message.
1646 log_debug(redefine, class, constantpool)("after pass 0: merge_cp_len=%d", merge_cp_length_p);
1647
1648 int scratch_i; // index into scratch_cp
1649 {
1650 // Pass 1a:
1651 // Compare scratch_cp entries to the old_cp entries that we have
1652 // already copied to *merge_cp_p. In this pass, we are eliminating
1653 // exact duplicates (matching entry at same index) so we only
1654 // compare entries in the common indice range.
1655 int increment = 1;
1656 int pass1a_length = MIN2(old_cp->length(), scratch_cp->length());
1657 for (scratch_i = 1; scratch_i < pass1a_length; scratch_i += increment) {
1658 switch (scratch_cp->tag_at(scratch_i).value()) {
1659 case JVM_CONSTANT_Double:
1660 case JVM_CONSTANT_Long:
1661 // double and long take two constant pool entries
1662 increment = 2;
1663 break;
1664
1665 default:
1666 increment = 1;
1667 break;
1668 }
1669
1670 bool match = scratch_cp->compare_entry_to(scratch_i, merge_cp_p, scratch_i);
1671 if (match) {
1672 // found a match at the same index so nothing more to do
1673 continue;
1674 }
1675
1676 int found_i = scratch_cp->find_matching_entry(scratch_i, merge_cp_p);
1677 if (found_i != 0) {
1678 guarantee(found_i != scratch_i,
1679 "compare_entry_to() and find_matching_entry() do not agree");
1680
1681 // Found a matching entry somewhere else in *merge_cp_p so
1682 // just need a mapping entry.
1683 map_index(scratch_cp, scratch_i, found_i);
1684 continue;
1685 }
1686
1687 // No match found so we have to append this entry and any unique
1688 // referenced entries to merge_cp_p.
1689 append_entry(scratch_cp, scratch_i, &merge_cp_p, &merge_cp_length_p);
1690 }
1691 }
1692
1693 log_debug(redefine, class, constantpool)
1694 ("after pass 1a: merge_cp_len=%d, scratch_i=%d, index_map_len=%d",
1695 merge_cp_length_p, scratch_i, _index_map_count);
1696
1697 if (scratch_i < scratch_cp->length()) {
1698 // Pass 1b:
1699 // old_cp is smaller than scratch_cp so there are entries in
1700 // scratch_cp that we have not yet processed. We take care of
1701 // those now.
1702 int increment = 1;
1703 for (; scratch_i < scratch_cp->length(); scratch_i += increment) {
1704 switch (scratch_cp->tag_at(scratch_i).value()) {
1705 case JVM_CONSTANT_Double:
1706 case JVM_CONSTANT_Long:
1707 // double and long take two constant pool entries
1708 increment = 2;
1709 break;
1710
1711 default:
1712 increment = 1;
1713 break;
1714 }
1715
1716 int found_i =
1717 scratch_cp->find_matching_entry(scratch_i, merge_cp_p);
1718 if (found_i != 0) {
1719 // Found a matching entry somewhere else in merge_cp_p so
1720 // just need a mapping entry.
1721 map_index(scratch_cp, scratch_i, found_i);
1722 continue;
1723 }
1724
1725 // No match found so we have to append this entry and any unique
1726 // referenced entries to merge_cp_p.
1727 append_entry(scratch_cp, scratch_i, &merge_cp_p, &merge_cp_length_p);
1728 }
1729
1730 log_debug(redefine, class, constantpool)
1731 ("after pass 1b: merge_cp_len=%d, scratch_i=%d, index_map_len=%d",
1732 merge_cp_length_p, scratch_i, _index_map_count);
1733 }
1734 finalize_operands_merge(merge_cp_p, CHECK_false);
1735
1736 return true;
1737 } // end merge_constant_pools()
1738
1739
1740 // Scoped object to clean up the constant pool(s) created for merging
1741 class MergeCPCleaner {
1742 ClassLoaderData* _loader_data;
1743 ConstantPool* _cp;
1744 ConstantPool* _scratch_cp;
1745 public:
1746 MergeCPCleaner(ClassLoaderData* loader_data, ConstantPool* merge_cp) :
1747 _loader_data(loader_data), _cp(merge_cp), _scratch_cp(nullptr) {}
1748 ~MergeCPCleaner() {
1749 _loader_data->add_to_deallocate_list(_cp);
1750 if (_scratch_cp != nullptr) {
1751 _loader_data->add_to_deallocate_list(_scratch_cp);
1752 }
1753 }
1754 void add_scratch_cp(ConstantPool* scratch_cp) { _scratch_cp = scratch_cp; }
1755 };
1756
1757 // Merge constant pools between the_class and scratch_class and
1758 // potentially rewrite bytecodes in scratch_class to use the merged
1759 // constant pool.
1760 jvmtiError VM_RedefineClasses::merge_cp_and_rewrite(
1761 InstanceKlass* the_class, InstanceKlass* scratch_class,
1762 TRAPS) {
1763 // worst case merged constant pool length is old and new combined
1764 int merge_cp_length = the_class->constants()->length()
1765 + scratch_class->constants()->length();
1766
1767 // Constant pools are not easily reused so we allocate a new one
1768 // each time.
1769 // merge_cp is created unsafe for concurrent GC processing. It
1770 // should be marked safe before discarding it. Even though
1771 // garbage, if it crosses a card boundary, it may be scanned
1772 // in order to find the start of the first complete object on the card.
1773 ClassLoaderData* loader_data = the_class->class_loader_data();
1774 ConstantPool* merge_cp_oop =
1775 ConstantPool::allocate(loader_data,
1776 merge_cp_length,
1777 CHECK_(JVMTI_ERROR_OUT_OF_MEMORY));
1778 MergeCPCleaner cp_cleaner(loader_data, merge_cp_oop);
1779
1780 HandleMark hm(THREAD); // make sure handles are cleared before
1781 // MergeCPCleaner clears out merge_cp_oop
1782 constantPoolHandle merge_cp(THREAD, merge_cp_oop);
1783
1784 // Get constants() from the old class because it could have been rewritten
1785 // while we were at a safepoint allocating a new constant pool.
1786 constantPoolHandle old_cp(THREAD, the_class->constants());
1787 constantPoolHandle scratch_cp(THREAD, scratch_class->constants());
1788
1789 // If the length changed, the class was redefined out from under us. Return
1790 // an error.
1791 if (merge_cp_length != the_class->constants()->length()
1792 + scratch_class->constants()->length()) {
1793 return JVMTI_ERROR_INTERNAL;
1794 }
1795
1796 // Update the version number of the constant pools (may keep scratch_cp)
1797 merge_cp->increment_and_save_version(old_cp->version());
1798 scratch_cp->increment_and_save_version(old_cp->version());
1799
1800 ResourceMark rm(THREAD);
1801 _index_map_count = 0;
1802 _index_map_p = new intArray(scratch_cp->length(), scratch_cp->length(), -1);
1803
1804 _operands_cur_length = ConstantPool::operand_array_length(old_cp->operands());
1805 _operands_index_map_count = 0;
1806 int operands_index_map_len = ConstantPool::operand_array_length(scratch_cp->operands());
1807 _operands_index_map_p = new intArray(operands_index_map_len, operands_index_map_len, -1);
1808
1809 // reference to the cp holder is needed for copy_operands()
1810 merge_cp->set_pool_holder(scratch_class);
1811 bool result = merge_constant_pools(old_cp, scratch_cp, merge_cp,
1812 merge_cp_length, THREAD);
1813 merge_cp->set_pool_holder(nullptr);
1814
1815 if (!result) {
1816 // The merge can fail due to memory allocation failure or due
1817 // to robustness checks.
1818 return JVMTI_ERROR_INTERNAL;
1819 }
1820
1821 // ensure merged constant pool size does not overflow u2
1822 if (merge_cp_length > 0xFFFF) {
1823 log_warning(redefine, class, constantpool)("Merged constant pool overflow: %d entries", merge_cp_length);
1824 return JVMTI_ERROR_INTERNAL;
1825 }
1826
1827 // Set dynamic constants attribute from the original CP.
1828 if (old_cp->has_dynamic_constant()) {
1829 scratch_cp->set_has_dynamic_constant();
1830 }
1831
1832 log_info(redefine, class, constantpool)("merge_cp_len=%d, index_map_len=%d", merge_cp_length, _index_map_count);
1833
1834 if (_index_map_count == 0) {
1835 // there is nothing to map between the new and merged constant pools
1836
1837 // Copy attributes from scratch_cp to merge_cp
1838 merge_cp->copy_fields(scratch_cp());
1839
1840 if (old_cp->length() == scratch_cp->length()) {
1841 // The old and new constant pools are the same length and the
1842 // index map is empty. This means that the three constant pools
1843 // are equivalent (but not the same). Unfortunately, the new
1844 // constant pool has not gone through link resolution nor have
1845 // the new class bytecodes gone through constant pool cache
1846 // rewriting so we can't use the old constant pool with the new
1847 // class.
1848
1849 // toss the merged constant pool at return
1850 } else if (old_cp->length() < scratch_cp->length()) {
1851 // The old constant pool has fewer entries than the new constant
1852 // pool and the index map is empty. This means the new constant
1853 // pool is a superset of the old constant pool. However, the old
1854 // class bytecodes have already gone through constant pool cache
1855 // rewriting so we can't use the new constant pool with the old
1856 // class.
1857
1858 // toss the merged constant pool at return
1859 } else {
1860 // The old constant pool has more entries than the new constant
1861 // pool and the index map is empty. This means that both the old
1862 // and merged constant pools are supersets of the new constant
1863 // pool.
1864
1865 // Replace the new constant pool with a shrunken copy of the
1866 // merged constant pool
1867 set_new_constant_pool(loader_data, scratch_class, merge_cp, merge_cp_length,
1868 CHECK_(JVMTI_ERROR_OUT_OF_MEMORY));
1869 // The new constant pool replaces scratch_cp so have cleaner clean it up.
1870 // It can't be cleaned up while there are handles to it.
1871 cp_cleaner.add_scratch_cp(scratch_cp());
1872 }
1873 } else {
1874 if (log_is_enabled(Trace, redefine, class, constantpool)) {
1875 // don't want to loop unless we are tracing
1876 int count = 0;
1877 for (int i = 1; i < _index_map_p->length(); i++) {
1878 int value = _index_map_p->at(i);
1879
1880 if (value != -1) {
1881 log_trace(redefine, class, constantpool)("index_map[%d]: old=%d new=%d", count, i, value);
1882 count++;
1883 }
1884 }
1885 }
1886
1887 // We have entries mapped between the new and merged constant pools
1888 // so we have to rewrite some constant pool references.
1889 if (!rewrite_cp_refs(scratch_class)) {
1890 return JVMTI_ERROR_INTERNAL;
1891 }
1892
1893 // Copy attributes from scratch_cp to merge_cp (should be done after rewrite_cp_refs())
1894 merge_cp->copy_fields(scratch_cp());
1895
1896 // Replace the new constant pool with a shrunken copy of the
1897 // merged constant pool so now the rewritten bytecodes have
1898 // valid references; the previous new constant pool will get
1899 // GCed.
1900 set_new_constant_pool(loader_data, scratch_class, merge_cp, merge_cp_length,
1901 CHECK_(JVMTI_ERROR_OUT_OF_MEMORY));
1902 // The new constant pool replaces scratch_cp so have cleaner clean it up.
1903 // It can't be cleaned up while there are handles to it.
1904 cp_cleaner.add_scratch_cp(scratch_cp());
1905 }
1906
1907 return JVMTI_ERROR_NONE;
1908 } // end merge_cp_and_rewrite()
1909
1910
1911 // Rewrite constant pool references in klass scratch_class.
1912 bool VM_RedefineClasses::rewrite_cp_refs(InstanceKlass* scratch_class) {
1913
1914 // rewrite constant pool references in the nest attributes:
1915 if (!rewrite_cp_refs_in_nest_attributes(scratch_class)) {
1916 // propagate failure back to caller
1917 return false;
1918 }
1919
1920 // rewrite constant pool references in the Record attribute:
1921 if (!rewrite_cp_refs_in_record_attribute(scratch_class)) {
1922 // propagate failure back to caller
1923 return false;
1924 }
1925
1926 // rewrite constant pool references in the PermittedSubclasses attribute:
1927 if (!rewrite_cp_refs_in_permitted_subclasses_attribute(scratch_class)) {
1928 // propagate failure back to caller
1929 return false;
1930 }
1931
1932 // rewrite constant pool references in the LoadableDescriptors attribute:
1933 if (!rewrite_cp_refs_in_loadable_descriptors_attribute(scratch_class)) {
1934 // propagate failure back to caller
1935 return false;
1936 }
1937
1938 // rewrite constant pool references in the methods:
1939 if (!rewrite_cp_refs_in_methods(scratch_class)) {
1940 // propagate failure back to caller
1941 return false;
1942 }
1943
1944 // rewrite constant pool references in the class_annotations:
1945 if (!rewrite_cp_refs_in_class_annotations(scratch_class)) {
1946 // propagate failure back to caller
1947 return false;
1948 }
1949
1950 // rewrite constant pool references in the fields_annotations:
1951 if (!rewrite_cp_refs_in_fields_annotations(scratch_class)) {
1952 // propagate failure back to caller
1953 return false;
1954 }
1955
1956 // rewrite constant pool references in the methods_annotations:
1957 if (!rewrite_cp_refs_in_methods_annotations(scratch_class)) {
1958 // propagate failure back to caller
1959 return false;
1960 }
1961
1962 // rewrite constant pool references in the methods_parameter_annotations:
1963 if (!rewrite_cp_refs_in_methods_parameter_annotations(scratch_class)) {
1964 // propagate failure back to caller
1965 return false;
1966 }
1967
1968 // rewrite constant pool references in the methods_default_annotations:
1969 if (!rewrite_cp_refs_in_methods_default_annotations(scratch_class)) {
1970 // propagate failure back to caller
1971 return false;
1972 }
1973
1974 // rewrite constant pool references in the class_type_annotations:
1975 if (!rewrite_cp_refs_in_class_type_annotations(scratch_class)) {
1976 // propagate failure back to caller
1977 return false;
1978 }
1979
1980 // rewrite constant pool references in the fields_type_annotations:
1981 if (!rewrite_cp_refs_in_fields_type_annotations(scratch_class)) {
1982 // propagate failure back to caller
1983 return false;
1984 }
1985
1986 // rewrite constant pool references in the methods_type_annotations:
1987 if (!rewrite_cp_refs_in_methods_type_annotations(scratch_class)) {
1988 // propagate failure back to caller
1989 return false;
1990 }
1991
1992 // There can be type annotations in the Code part of a method_info attribute.
1993 // These annotations are not accessible, even by reflection.
1994 // Currently they are not even parsed by the ClassFileParser.
1995 // If runtime access is added they will also need to be rewritten.
1996
1997 // rewrite source file name index:
1998 u2 source_file_name_idx = scratch_class->source_file_name_index();
1999 if (source_file_name_idx != 0) {
2000 u2 new_source_file_name_idx = find_new_index(source_file_name_idx);
2001 if (new_source_file_name_idx != 0) {
2002 scratch_class->set_source_file_name_index(new_source_file_name_idx);
2003 }
2004 }
2005
2006 // rewrite class generic signature index:
2007 u2 generic_signature_index = scratch_class->generic_signature_index();
2008 if (generic_signature_index != 0) {
2009 u2 new_generic_signature_index = find_new_index(generic_signature_index);
2010 if (new_generic_signature_index != 0) {
2011 scratch_class->set_generic_signature_index(new_generic_signature_index);
2012 }
2013 }
2014
2015 return true;
2016 } // end rewrite_cp_refs()
2017
2018 // Rewrite constant pool references in the NestHost and NestMembers attributes.
2019 bool VM_RedefineClasses::rewrite_cp_refs_in_nest_attributes(
2020 InstanceKlass* scratch_class) {
2021
2022 u2 cp_index = scratch_class->nest_host_index();
2023 if (cp_index != 0) {
2024 scratch_class->set_nest_host_index(find_new_index(cp_index));
2025 }
2026 Array<u2>* nest_members = scratch_class->nest_members();
2027 for (int i = 0; i < nest_members->length(); i++) {
2028 u2 cp_index = nest_members->at(i);
2029 nest_members->at_put(i, find_new_index(cp_index));
2030 }
2031 return true;
2032 }
2033
2034 // Rewrite constant pool references in the Record attribute.
2035 bool VM_RedefineClasses::rewrite_cp_refs_in_record_attribute(InstanceKlass* scratch_class) {
2036 Array<RecordComponent*>* components = scratch_class->record_components();
2037 if (components != nullptr) {
2038 for (int i = 0; i < components->length(); i++) {
2039 RecordComponent* component = components->at(i);
2040 u2 cp_index = component->name_index();
2041 component->set_name_index(find_new_index(cp_index));
2042 cp_index = component->descriptor_index();
2043 component->set_descriptor_index(find_new_index(cp_index));
2044 cp_index = component->generic_signature_index();
2045 if (cp_index != 0) {
2046 component->set_generic_signature_index(find_new_index(cp_index));
2047 }
2048
2049 AnnotationArray* annotations = component->annotations();
2050 if (annotations != nullptr && annotations->length() != 0) {
2051 int byte_i = 0; // byte index into annotations
2052 if (!rewrite_cp_refs_in_annotations_typeArray(annotations, byte_i)) {
2053 log_debug(redefine, class, annotation)("bad record_component_annotations at %d", i);
2054 // propagate failure back to caller
2055 return false;
2056 }
2057 }
2058
2059 AnnotationArray* type_annotations = component->type_annotations();
2060 if (type_annotations != nullptr && type_annotations->length() != 0) {
2061 int byte_i = 0; // byte index into annotations
2062 if (!rewrite_cp_refs_in_annotations_typeArray(type_annotations, byte_i)) {
2063 log_debug(redefine, class, annotation)("bad record_component_type_annotations at %d", i);
2064 // propagate failure back to caller
2065 return false;
2066 }
2067 }
2068 }
2069 }
2070 return true;
2071 }
2072
2073 // Rewrite constant pool references in the PermittedSubclasses attribute.
2074 bool VM_RedefineClasses::rewrite_cp_refs_in_permitted_subclasses_attribute(
2075 InstanceKlass* scratch_class) {
2076
2077 Array<u2>* permitted_subclasses = scratch_class->permitted_subclasses();
2078 assert(permitted_subclasses != nullptr, "unexpected null permitted_subclasses");
2079 for (int i = 0; i < permitted_subclasses->length(); i++) {
2080 u2 cp_index = permitted_subclasses->at(i);
2081 permitted_subclasses->at_put(i, find_new_index(cp_index));
2082 }
2083 return true;
2084 }
2085
2086 // Rewrite constant pool references in the LoadableDescriptors attribute.
2087 bool VM_RedefineClasses::rewrite_cp_refs_in_loadable_descriptors_attribute(
2088 InstanceKlass* scratch_class) {
2089
2090 Array<u2>* loadable_descriptors = scratch_class->loadable_descriptors();
2091 assert(loadable_descriptors != nullptr, "unexpected null loadable_descriptors");
2092 for (int i = 0; i < loadable_descriptors->length(); i++) {
2093 u2 cp_index = loadable_descriptors->at(i);
2094 loadable_descriptors->at_put(i, find_new_index(cp_index));
2095 }
2096 return true;
2097 }
2098
2099 // Rewrite constant pool references in the methods.
2100 bool VM_RedefineClasses::rewrite_cp_refs_in_methods(InstanceKlass* scratch_class) {
2101
2102 Array<Method*>* methods = scratch_class->methods();
2103
2104 if (methods == nullptr || methods->length() == 0) {
2105 // no methods so nothing to do
2106 return true;
2107 }
2108
2109 JavaThread* THREAD = JavaThread::current(); // For exception macros.
2110 ExceptionMark em(THREAD);
2111
2112 // rewrite constant pool references in the methods:
2113 for (int i = methods->length() - 1; i >= 0; i--) {
2114 methodHandle method(THREAD, methods->at(i));
2115 methodHandle new_method;
2116 rewrite_cp_refs_in_method(method, &new_method, THREAD);
2117 if (!new_method.is_null()) {
2118 // the method has been replaced so save the new method version
2119 // even in the case of an exception. original method is on the
2120 // deallocation list.
2121 methods->at_put(i, new_method());
2122 }
2123 if (HAS_PENDING_EXCEPTION) {
2124 Symbol* ex_name = PENDING_EXCEPTION->klass()->name();
2125 log_info(redefine, class, load, exceptions)("rewrite_cp_refs_in_method exception: '%s'", ex_name->as_C_string());
2126 // Need to clear pending exception here as the super caller sets
2127 // the JVMTI_ERROR_INTERNAL if the returned value is false.
2128 CLEAR_PENDING_EXCEPTION;
2129 return false;
2130 }
2131 }
2132
2133 return true;
2134 }
2135
2136
2137 // Rewrite constant pool references in the specific method. This code
2138 // was adapted from Rewriter::rewrite_method().
2139 void VM_RedefineClasses::rewrite_cp_refs_in_method(methodHandle method,
2140 methodHandle *new_method_p, TRAPS) {
2141
2142 *new_method_p = methodHandle(); // default is no new method
2143
2144 // We cache a pointer to the bytecodes here in code_base. If GC
2145 // moves the Method*, then the bytecodes will also move which
2146 // will likely cause a crash. We create a NoSafepointVerifier
2147 // object to detect whether we pass a possible safepoint in this
2148 // code block.
2149 NoSafepointVerifier nsv;
2150
2151 // Bytecodes and their length
2152 address code_base = method->code_base();
2153 int code_length = method->code_size();
2154
2155 int bc_length;
2156 for (int bci = 0; bci < code_length; bci += bc_length) {
2157 address bcp = code_base + bci;
2158 Bytecodes::Code c = (Bytecodes::Code)(*bcp);
2159
2160 bc_length = Bytecodes::length_for(c);
2161 if (bc_length == 0) {
2162 // More complicated bytecodes report a length of zero so
2163 // we have to try again a slightly different way.
2164 bc_length = Bytecodes::length_at(method(), bcp);
2165 }
2166
2167 assert(bc_length != 0, "impossible bytecode length");
2168
2169 switch (c) {
2170 case Bytecodes::_ldc:
2171 {
2172 u1 cp_index = *(bcp + 1);
2173 u2 new_index = find_new_index(cp_index);
2174
2175 if (StressLdcRewrite && new_index == 0) {
2176 // If we are stressing ldc -> ldc_w rewriting, then we
2177 // always need a new_index value.
2178 new_index = cp_index;
2179 }
2180 if (new_index != 0) {
2181 // the original index is mapped so we have more work to do
2182 if (!StressLdcRewrite && new_index <= max_jubyte) {
2183 // The new value can still use ldc instead of ldc_w
2184 // unless we are trying to stress ldc -> ldc_w rewriting
2185 log_trace(redefine, class, constantpool)
2186 ("%s@" INTPTR_FORMAT " old=%d, new=%d", Bytecodes::name(c), p2i(bcp), cp_index, new_index);
2187 // We checked that new_index fits in a u1 so this cast is safe
2188 *(bcp + 1) = (u1)new_index;
2189 } else {
2190 log_trace(redefine, class, constantpool)
2191 ("%s->ldc_w@" INTPTR_FORMAT " old=%d, new=%d", Bytecodes::name(c), p2i(bcp), cp_index, new_index);
2192 // the new value needs ldc_w instead of ldc
2193 u_char inst_buffer[4]; // max instruction size is 4 bytes
2194 bcp = (address)inst_buffer;
2195 // construct new instruction sequence
2196 *bcp = Bytecodes::_ldc_w;
2197 bcp++;
2198 // Rewriter::rewrite_method() does not rewrite ldc -> ldc_w.
2199 // See comment below for difference between put_Java_u2()
2200 // and put_native_u2().
2201 Bytes::put_Java_u2(bcp, new_index);
2202
2203 Relocator rc(method, nullptr /* no RelocatorListener needed */);
2204 methodHandle m;
2205 {
2206 PauseNoSafepointVerifier pnsv(&nsv);
2207
2208 // ldc is 2 bytes and ldc_w is 3 bytes
2209 m = rc.insert_space_at(bci, 3, inst_buffer, CHECK);
2210 }
2211
2212 // return the new method so that the caller can update
2213 // the containing class
2214 *new_method_p = method = m;
2215 // switch our bytecode processing loop from the old method
2216 // to the new method
2217 code_base = method->code_base();
2218 code_length = method->code_size();
2219 bcp = code_base + bci;
2220 c = (Bytecodes::Code)(*bcp);
2221 bc_length = Bytecodes::length_for(c);
2222 assert(bc_length != 0, "sanity check");
2223 } // end we need ldc_w instead of ldc
2224 } // end if there is a mapped index
2225 } break;
2226
2227 // these bytecodes have a two-byte constant pool index
2228 case Bytecodes::_anewarray : // fall through
2229 case Bytecodes::_checkcast : // fall through
2230 case Bytecodes::_getfield : // fall through
2231 case Bytecodes::_getstatic : // fall through
2232 case Bytecodes::_instanceof : // fall through
2233 case Bytecodes::_invokedynamic : // fall through
2234 case Bytecodes::_invokeinterface: // fall through
2235 case Bytecodes::_invokespecial : // fall through
2236 case Bytecodes::_invokestatic : // fall through
2237 case Bytecodes::_invokevirtual : // fall through
2238 case Bytecodes::_ldc_w : // fall through
2239 case Bytecodes::_ldc2_w : // fall through
2240 case Bytecodes::_multianewarray : // fall through
2241 case Bytecodes::_new : // fall through
2242 case Bytecodes::_putfield : // fall through
2243 case Bytecodes::_putstatic :
2244 {
2245 address p = bcp + 1;
2246 int cp_index = Bytes::get_Java_u2(p);
2247 u2 new_index = find_new_index(cp_index);
2248 if (new_index != 0) {
2249 // the original index is mapped so update w/ new value
2250 log_trace(redefine, class, constantpool)
2251 ("%s@" INTPTR_FORMAT " old=%d, new=%d", Bytecodes::name(c),p2i(bcp), cp_index, new_index);
2252 // Rewriter::rewrite_method() uses put_native_u2() in this
2253 // situation because it is reusing the constant pool index
2254 // location for a native index into the ConstantPoolCache.
2255 // Since we are updating the constant pool index prior to
2256 // verification and ConstantPoolCache initialization, we
2257 // need to keep the new index in Java byte order.
2258 Bytes::put_Java_u2(p, new_index);
2259 }
2260 } break;
2261 default:
2262 break;
2263 }
2264 } // end for each bytecode
2265 } // end rewrite_cp_refs_in_method()
2266
2267
2268 // Rewrite constant pool references in the class_annotations field.
2269 bool VM_RedefineClasses::rewrite_cp_refs_in_class_annotations(InstanceKlass* scratch_class) {
2270
2271 AnnotationArray* class_annotations = scratch_class->class_annotations();
2272 if (class_annotations == nullptr || class_annotations->length() == 0) {
2273 // no class_annotations so nothing to do
2274 return true;
2275 }
2276
2277 log_debug(redefine, class, annotation)("class_annotations length=%d", class_annotations->length());
2278
2279 int byte_i = 0; // byte index into class_annotations
2280 return rewrite_cp_refs_in_annotations_typeArray(class_annotations, byte_i);
2281 }
2282
2283
2284 // Rewrite constant pool references in an annotations typeArray. This
2285 // "structure" is adapted from the RuntimeVisibleAnnotations_attribute
2286 // that is described in section 4.8.15 of the 2nd-edition of the VM spec:
2287 //
2288 // annotations_typeArray {
2289 // u2 num_annotations;
2290 // annotation annotations[num_annotations];
2291 // }
2292 //
2293 bool VM_RedefineClasses::rewrite_cp_refs_in_annotations_typeArray(
2294 AnnotationArray* annotations_typeArray, int &byte_i_ref) {
2295
2296 if ((byte_i_ref + 2) > annotations_typeArray->length()) {
2297 // not enough room for num_annotations field
2298 log_debug(redefine, class, annotation)("length() is too small for num_annotations field");
2299 return false;
2300 }
2301
2302 u2 num_annotations = Bytes::get_Java_u2((address)
2303 annotations_typeArray->adr_at(byte_i_ref));
2304 byte_i_ref += 2;
2305
2306 log_debug(redefine, class, annotation)("num_annotations=%d", num_annotations);
2307
2308 int calc_num_annotations = 0;
2309 for (; calc_num_annotations < num_annotations; calc_num_annotations++) {
2310 if (!rewrite_cp_refs_in_annotation_struct(annotations_typeArray, byte_i_ref)) {
2311 log_debug(redefine, class, annotation)("bad annotation_struct at %d", calc_num_annotations);
2312 // propagate failure back to caller
2313 return false;
2314 }
2315 }
2316 assert(num_annotations == calc_num_annotations, "sanity check");
2317
2318 return true;
2319 } // end rewrite_cp_refs_in_annotations_typeArray()
2320
2321
2322 // Rewrite constant pool references in the annotation struct portion of
2323 // an annotations_typeArray. This "structure" is from section 4.8.15 of
2324 // the 2nd-edition of the VM spec:
2325 //
2326 // struct annotation {
2327 // u2 type_index;
2328 // u2 num_element_value_pairs;
2329 // {
2330 // u2 element_name_index;
2331 // element_value value;
2332 // } element_value_pairs[num_element_value_pairs];
2333 // }
2334 //
2335 bool VM_RedefineClasses::rewrite_cp_refs_in_annotation_struct(
2336 AnnotationArray* annotations_typeArray, int &byte_i_ref) {
2337 if ((byte_i_ref + 2 + 2) > annotations_typeArray->length()) {
2338 // not enough room for smallest annotation_struct
2339 log_debug(redefine, class, annotation)("length() is too small for annotation_struct");
2340 return false;
2341 }
2342
2343 u2 type_index = rewrite_cp_ref_in_annotation_data(annotations_typeArray,
2344 byte_i_ref, "type_index");
2345
2346 u2 num_element_value_pairs = Bytes::get_Java_u2((address)
2347 annotations_typeArray->adr_at(byte_i_ref));
2348 byte_i_ref += 2;
2349
2350 log_debug(redefine, class, annotation)
2351 ("type_index=%d num_element_value_pairs=%d", type_index, num_element_value_pairs);
2352
2353 int calc_num_element_value_pairs = 0;
2354 for (; calc_num_element_value_pairs < num_element_value_pairs;
2355 calc_num_element_value_pairs++) {
2356 if ((byte_i_ref + 2) > annotations_typeArray->length()) {
2357 // not enough room for another element_name_index, let alone
2358 // the rest of another component
2359 log_debug(redefine, class, annotation)("length() is too small for element_name_index");
2360 return false;
2361 }
2362
2363 u2 element_name_index = rewrite_cp_ref_in_annotation_data(
2364 annotations_typeArray, byte_i_ref,
2365 "element_name_index");
2366
2367 log_debug(redefine, class, annotation)("element_name_index=%d", element_name_index);
2368
2369 if (!rewrite_cp_refs_in_element_value(annotations_typeArray, byte_i_ref)) {
2370 log_debug(redefine, class, annotation)("bad element_value at %d", calc_num_element_value_pairs);
2371 // propagate failure back to caller
2372 return false;
2373 }
2374 } // end for each component
2375 assert(num_element_value_pairs == calc_num_element_value_pairs,
2376 "sanity check");
2377
2378 return true;
2379 } // end rewrite_cp_refs_in_annotation_struct()
2380
2381
2382 // Rewrite a constant pool reference at the current position in
2383 // annotations_typeArray if needed. Returns the original constant
2384 // pool reference if a rewrite was not needed or the new constant
2385 // pool reference if a rewrite was needed.
2386 u2 VM_RedefineClasses::rewrite_cp_ref_in_annotation_data(
2387 AnnotationArray* annotations_typeArray, int &byte_i_ref,
2388 const char * trace_mesg) {
2389
2390 address cp_index_addr = (address)
2391 annotations_typeArray->adr_at(byte_i_ref);
2392 u2 old_cp_index = Bytes::get_Java_u2(cp_index_addr);
2393 u2 new_cp_index = find_new_index(old_cp_index);
2394 if (new_cp_index != 0) {
2395 log_debug(redefine, class, annotation)("mapped old %s=%d", trace_mesg, old_cp_index);
2396 Bytes::put_Java_u2(cp_index_addr, new_cp_index);
2397 old_cp_index = new_cp_index;
2398 }
2399 byte_i_ref += 2;
2400 return old_cp_index;
2401 }
2402
2403
2404 // Rewrite constant pool references in the element_value portion of an
2405 // annotations_typeArray. This "structure" is from section 4.8.15.1 of
2406 // the 2nd-edition of the VM spec:
2407 //
2408 // struct element_value {
2409 // u1 tag;
2410 // union {
2411 // u2 const_value_index;
2412 // {
2413 // u2 type_name_index;
2414 // u2 const_name_index;
2415 // } enum_const_value;
2416 // u2 class_info_index;
2417 // annotation annotation_value;
2418 // struct {
2419 // u2 num_values;
2420 // element_value values[num_values];
2421 // } array_value;
2422 // } value;
2423 // }
2424 //
2425 bool VM_RedefineClasses::rewrite_cp_refs_in_element_value(
2426 AnnotationArray* annotations_typeArray, int &byte_i_ref) {
2427
2428 if ((byte_i_ref + 1) > annotations_typeArray->length()) {
2429 // not enough room for a tag let alone the rest of an element_value
2430 log_debug(redefine, class, annotation)("length() is too small for a tag");
2431 return false;
2432 }
2433
2434 u1 tag = annotations_typeArray->at(byte_i_ref);
2435 byte_i_ref++;
2436 log_debug(redefine, class, annotation)("tag='%c'", tag);
2437
2438 switch (tag) {
2439 // These BaseType tag values are from Table 4.2 in VM spec:
2440 case JVM_SIGNATURE_BYTE:
2441 case JVM_SIGNATURE_CHAR:
2442 case JVM_SIGNATURE_DOUBLE:
2443 case JVM_SIGNATURE_FLOAT:
2444 case JVM_SIGNATURE_INT:
2445 case JVM_SIGNATURE_LONG:
2446 case JVM_SIGNATURE_SHORT:
2447 case JVM_SIGNATURE_BOOLEAN:
2448
2449 // The remaining tag values are from Table 4.8 in the 2nd-edition of
2450 // the VM spec:
2451 case 's':
2452 {
2453 // For the above tag values (including the BaseType values),
2454 // value.const_value_index is right union field.
2455
2456 if ((byte_i_ref + 2) > annotations_typeArray->length()) {
2457 // not enough room for a const_value_index
2458 log_debug(redefine, class, annotation)("length() is too small for a const_value_index");
2459 return false;
2460 }
2461
2462 u2 const_value_index = rewrite_cp_ref_in_annotation_data(
2463 annotations_typeArray, byte_i_ref,
2464 "const_value_index");
2465
2466 log_debug(redefine, class, annotation)("const_value_index=%d", const_value_index);
2467 } break;
2468
2469 case 'e':
2470 {
2471 // for the above tag value, value.enum_const_value is right union field
2472
2473 if ((byte_i_ref + 4) > annotations_typeArray->length()) {
2474 // not enough room for a enum_const_value
2475 log_debug(redefine, class, annotation)("length() is too small for a enum_const_value");
2476 return false;
2477 }
2478
2479 u2 type_name_index = rewrite_cp_ref_in_annotation_data(
2480 annotations_typeArray, byte_i_ref,
2481 "type_name_index");
2482
2483 u2 const_name_index = rewrite_cp_ref_in_annotation_data(
2484 annotations_typeArray, byte_i_ref,
2485 "const_name_index");
2486
2487 log_debug(redefine, class, annotation)
2488 ("type_name_index=%d const_name_index=%d", type_name_index, const_name_index);
2489 } break;
2490
2491 case 'c':
2492 {
2493 // for the above tag value, value.class_info_index is right union field
2494
2495 if ((byte_i_ref + 2) > annotations_typeArray->length()) {
2496 // not enough room for a class_info_index
2497 log_debug(redefine, class, annotation)("length() is too small for a class_info_index");
2498 return false;
2499 }
2500
2501 u2 class_info_index = rewrite_cp_ref_in_annotation_data(
2502 annotations_typeArray, byte_i_ref,
2503 "class_info_index");
2504
2505 log_debug(redefine, class, annotation)("class_info_index=%d", class_info_index);
2506 } break;
2507
2508 case '@':
2509 // For the above tag value, value.attr_value is the right union
2510 // field. This is a nested annotation.
2511 if (!rewrite_cp_refs_in_annotation_struct(annotations_typeArray, byte_i_ref)) {
2512 // propagate failure back to caller
2513 return false;
2514 }
2515 break;
2516
2517 case JVM_SIGNATURE_ARRAY:
2518 {
2519 if ((byte_i_ref + 2) > annotations_typeArray->length()) {
2520 // not enough room for a num_values field
2521 log_debug(redefine, class, annotation)("length() is too small for a num_values field");
2522 return false;
2523 }
2524
2525 // For the above tag value, value.array_value is the right union
2526 // field. This is an array of nested element_value.
2527 u2 num_values = Bytes::get_Java_u2((address)
2528 annotations_typeArray->adr_at(byte_i_ref));
2529 byte_i_ref += 2;
2530 log_debug(redefine, class, annotation)("num_values=%d", num_values);
2531
2532 int calc_num_values = 0;
2533 for (; calc_num_values < num_values; calc_num_values++) {
2534 if (!rewrite_cp_refs_in_element_value(annotations_typeArray, byte_i_ref)) {
2535 log_debug(redefine, class, annotation)("bad nested element_value at %d", calc_num_values);
2536 // propagate failure back to caller
2537 return false;
2538 }
2539 }
2540 assert(num_values == calc_num_values, "sanity check");
2541 } break;
2542
2543 default:
2544 log_debug(redefine, class, annotation)("bad tag=0x%x", tag);
2545 return false;
2546 } // end decode tag field
2547
2548 return true;
2549 } // end rewrite_cp_refs_in_element_value()
2550
2551
2552 // Rewrite constant pool references in a fields_annotations field.
2553 bool VM_RedefineClasses::rewrite_cp_refs_in_fields_annotations(
2554 InstanceKlass* scratch_class) {
2555
2556 Array<AnnotationArray*>* fields_annotations = scratch_class->fields_annotations();
2557
2558 if (fields_annotations == nullptr || fields_annotations->length() == 0) {
2559 // no fields_annotations so nothing to do
2560 return true;
2561 }
2562
2563 log_debug(redefine, class, annotation)("fields_annotations length=%d", fields_annotations->length());
2564
2565 for (int i = 0; i < fields_annotations->length(); i++) {
2566 AnnotationArray* field_annotations = fields_annotations->at(i);
2567 if (field_annotations == nullptr || field_annotations->length() == 0) {
2568 // this field does not have any annotations so skip it
2569 continue;
2570 }
2571
2572 int byte_i = 0; // byte index into field_annotations
2573 if (!rewrite_cp_refs_in_annotations_typeArray(field_annotations, byte_i)) {
2574 log_debug(redefine, class, annotation)("bad field_annotations at %d", i);
2575 // propagate failure back to caller
2576 return false;
2577 }
2578 }
2579
2580 return true;
2581 } // end rewrite_cp_refs_in_fields_annotations()
2582
2583
2584 // Rewrite constant pool references in a methods_annotations field.
2585 bool VM_RedefineClasses::rewrite_cp_refs_in_methods_annotations(
2586 InstanceKlass* scratch_class) {
2587
2588 for (int i = 0; i < scratch_class->methods()->length(); i++) {
2589 Method* m = scratch_class->methods()->at(i);
2590 AnnotationArray* method_annotations = m->constMethod()->method_annotations();
2591
2592 if (method_annotations == nullptr || method_annotations->length() == 0) {
2593 // this method does not have any annotations so skip it
2594 continue;
2595 }
2596
2597 int byte_i = 0; // byte index into method_annotations
2598 if (!rewrite_cp_refs_in_annotations_typeArray(method_annotations, byte_i)) {
2599 log_debug(redefine, class, annotation)("bad method_annotations at %d", i);
2600 // propagate failure back to caller
2601 return false;
2602 }
2603 }
2604
2605 return true;
2606 } // end rewrite_cp_refs_in_methods_annotations()
2607
2608
2609 // Rewrite constant pool references in a methods_parameter_annotations
2610 // field. This "structure" is adapted from the
2611 // RuntimeVisibleParameterAnnotations_attribute described in section
2612 // 4.8.17 of the 2nd-edition of the VM spec:
2613 //
2614 // methods_parameter_annotations_typeArray {
2615 // u1 num_parameters;
2616 // {
2617 // u2 num_annotations;
2618 // annotation annotations[num_annotations];
2619 // } parameter_annotations[num_parameters];
2620 // }
2621 //
2622 bool VM_RedefineClasses::rewrite_cp_refs_in_methods_parameter_annotations(
2623 InstanceKlass* scratch_class) {
2624
2625 for (int i = 0; i < scratch_class->methods()->length(); i++) {
2626 Method* m = scratch_class->methods()->at(i);
2627 AnnotationArray* method_parameter_annotations = m->constMethod()->parameter_annotations();
2628 if (method_parameter_annotations == nullptr
2629 || method_parameter_annotations->length() == 0) {
2630 // this method does not have any parameter annotations so skip it
2631 continue;
2632 }
2633
2634 if (method_parameter_annotations->length() < 1) {
2635 // not enough room for a num_parameters field
2636 log_debug(redefine, class, annotation)("length() is too small for a num_parameters field at %d", i);
2637 return false;
2638 }
2639
2640 int byte_i = 0; // byte index into method_parameter_annotations
2641
2642 u1 num_parameters = method_parameter_annotations->at(byte_i);
2643 byte_i++;
2644
2645 log_debug(redefine, class, annotation)("num_parameters=%d", num_parameters);
2646
2647 int calc_num_parameters = 0;
2648 for (; calc_num_parameters < num_parameters; calc_num_parameters++) {
2649 if (!rewrite_cp_refs_in_annotations_typeArray(method_parameter_annotations, byte_i)) {
2650 log_debug(redefine, class, annotation)("bad method_parameter_annotations at %d", calc_num_parameters);
2651 // propagate failure back to caller
2652 return false;
2653 }
2654 }
2655 assert(num_parameters == calc_num_parameters, "sanity check");
2656 }
2657
2658 return true;
2659 } // end rewrite_cp_refs_in_methods_parameter_annotations()
2660
2661
2662 // Rewrite constant pool references in a methods_default_annotations
2663 // field. This "structure" is adapted from the AnnotationDefault_attribute
2664 // that is described in section 4.8.19 of the 2nd-edition of the VM spec:
2665 //
2666 // methods_default_annotations_typeArray {
2667 // element_value default_value;
2668 // }
2669 //
2670 bool VM_RedefineClasses::rewrite_cp_refs_in_methods_default_annotations(
2671 InstanceKlass* scratch_class) {
2672
2673 for (int i = 0; i < scratch_class->methods()->length(); i++) {
2674 Method* m = scratch_class->methods()->at(i);
2675 AnnotationArray* method_default_annotations = m->constMethod()->default_annotations();
2676 if (method_default_annotations == nullptr
2677 || method_default_annotations->length() == 0) {
2678 // this method does not have any default annotations so skip it
2679 continue;
2680 }
2681
2682 int byte_i = 0; // byte index into method_default_annotations
2683
2684 if (!rewrite_cp_refs_in_element_value(
2685 method_default_annotations, byte_i)) {
2686 log_debug(redefine, class, annotation)("bad default element_value at %d", i);
2687 // propagate failure back to caller
2688 return false;
2689 }
2690 }
2691
2692 return true;
2693 } // end rewrite_cp_refs_in_methods_default_annotations()
2694
2695
2696 // Rewrite constant pool references in a class_type_annotations field.
2697 bool VM_RedefineClasses::rewrite_cp_refs_in_class_type_annotations(
2698 InstanceKlass* scratch_class) {
2699
2700 AnnotationArray* class_type_annotations = scratch_class->class_type_annotations();
2701 if (class_type_annotations == nullptr || class_type_annotations->length() == 0) {
2702 // no class_type_annotations so nothing to do
2703 return true;
2704 }
2705
2706 log_debug(redefine, class, annotation)("class_type_annotations length=%d", class_type_annotations->length());
2707
2708 int byte_i = 0; // byte index into class_type_annotations
2709 return rewrite_cp_refs_in_type_annotations_typeArray(class_type_annotations,
2710 byte_i, "ClassFile");
2711 } // end rewrite_cp_refs_in_class_type_annotations()
2712
2713
2714 // Rewrite constant pool references in a fields_type_annotations field.
2715 bool VM_RedefineClasses::rewrite_cp_refs_in_fields_type_annotations(InstanceKlass* scratch_class) {
2716
2717 Array<AnnotationArray*>* fields_type_annotations = scratch_class->fields_type_annotations();
2718 if (fields_type_annotations == nullptr || fields_type_annotations->length() == 0) {
2719 // no fields_type_annotations so nothing to do
2720 return true;
2721 }
2722
2723 log_debug(redefine, class, annotation)("fields_type_annotations length=%d", fields_type_annotations->length());
2724
2725 for (int i = 0; i < fields_type_annotations->length(); i++) {
2726 AnnotationArray* field_type_annotations = fields_type_annotations->at(i);
2727 if (field_type_annotations == nullptr || field_type_annotations->length() == 0) {
2728 // this field does not have any annotations so skip it
2729 continue;
2730 }
2731
2732 int byte_i = 0; // byte index into field_type_annotations
2733 if (!rewrite_cp_refs_in_type_annotations_typeArray(field_type_annotations,
2734 byte_i, "field_info")) {
2735 log_debug(redefine, class, annotation)("bad field_type_annotations at %d", i);
2736 // propagate failure back to caller
2737 return false;
2738 }
2739 }
2740
2741 return true;
2742 } // end rewrite_cp_refs_in_fields_type_annotations()
2743
2744
2745 // Rewrite constant pool references in a methods_type_annotations field.
2746 bool VM_RedefineClasses::rewrite_cp_refs_in_methods_type_annotations(
2747 InstanceKlass* scratch_class) {
2748
2749 for (int i = 0; i < scratch_class->methods()->length(); i++) {
2750 Method* m = scratch_class->methods()->at(i);
2751 AnnotationArray* method_type_annotations = m->constMethod()->type_annotations();
2752
2753 if (method_type_annotations == nullptr || method_type_annotations->length() == 0) {
2754 // this method does not have any annotations so skip it
2755 continue;
2756 }
2757
2758 log_debug(redefine, class, annotation)("methods type_annotations length=%d", method_type_annotations->length());
2759
2760 int byte_i = 0; // byte index into method_type_annotations
2761 if (!rewrite_cp_refs_in_type_annotations_typeArray(method_type_annotations,
2762 byte_i, "method_info")) {
2763 log_debug(redefine, class, annotation)("bad method_type_annotations at %d", i);
2764 // propagate failure back to caller
2765 return false;
2766 }
2767 }
2768
2769 return true;
2770 } // end rewrite_cp_refs_in_methods_type_annotations()
2771
2772
2773 // Rewrite constant pool references in a type_annotations
2774 // field. This "structure" is adapted from the
2775 // RuntimeVisibleTypeAnnotations_attribute described in
2776 // section 4.7.20 of the Java SE 8 Edition of the VM spec:
2777 //
2778 // type_annotations_typeArray {
2779 // u2 num_annotations;
2780 // type_annotation annotations[num_annotations];
2781 // }
2782 //
2783 bool VM_RedefineClasses::rewrite_cp_refs_in_type_annotations_typeArray(
2784 AnnotationArray* type_annotations_typeArray, int &byte_i_ref,
2785 const char * location_mesg) {
2786
2787 if ((byte_i_ref + 2) > type_annotations_typeArray->length()) {
2788 // not enough room for num_annotations field
2789 log_debug(redefine, class, annotation)("length() is too small for num_annotations field");
2790 return false;
2791 }
2792
2793 u2 num_annotations = Bytes::get_Java_u2((address)
2794 type_annotations_typeArray->adr_at(byte_i_ref));
2795 byte_i_ref += 2;
2796
2797 log_debug(redefine, class, annotation)("num_type_annotations=%d", num_annotations);
2798
2799 int calc_num_annotations = 0;
2800 for (; calc_num_annotations < num_annotations; calc_num_annotations++) {
2801 if (!rewrite_cp_refs_in_type_annotation_struct(type_annotations_typeArray,
2802 byte_i_ref, location_mesg)) {
2803 log_debug(redefine, class, annotation)("bad type_annotation_struct at %d", calc_num_annotations);
2804 // propagate failure back to caller
2805 return false;
2806 }
2807 }
2808 assert(num_annotations == calc_num_annotations, "sanity check");
2809
2810 if (byte_i_ref != type_annotations_typeArray->length()) {
2811 log_debug(redefine, class, annotation)
2812 ("read wrong amount of bytes at end of processing type_annotations_typeArray (%d of %d bytes were read)",
2813 byte_i_ref, type_annotations_typeArray->length());
2814 return false;
2815 }
2816
2817 return true;
2818 } // end rewrite_cp_refs_in_type_annotations_typeArray()
2819
2820
2821 // Rewrite constant pool references in a type_annotation
2822 // field. This "structure" is adapted from the
2823 // RuntimeVisibleTypeAnnotations_attribute described in
2824 // section 4.7.20 of the Java SE 8 Edition of the VM spec:
2825 //
2826 // type_annotation {
2827 // u1 target_type;
2828 // union {
2829 // type_parameter_target;
2830 // supertype_target;
2831 // type_parameter_bound_target;
2832 // empty_target;
2833 // method_formal_parameter_target;
2834 // throws_target;
2835 // localvar_target;
2836 // catch_target;
2837 // offset_target;
2838 // type_argument_target;
2839 // } target_info;
2840 // type_path target_path;
2841 // annotation anno;
2842 // }
2843 //
2844 bool VM_RedefineClasses::rewrite_cp_refs_in_type_annotation_struct(
2845 AnnotationArray* type_annotations_typeArray, int &byte_i_ref,
2846 const char * location_mesg) {
2847
2848 if (!skip_type_annotation_target(type_annotations_typeArray,
2849 byte_i_ref, location_mesg)) {
2850 return false;
2851 }
2852
2853 if (!skip_type_annotation_type_path(type_annotations_typeArray, byte_i_ref)) {
2854 return false;
2855 }
2856
2857 if (!rewrite_cp_refs_in_annotation_struct(type_annotations_typeArray, byte_i_ref)) {
2858 return false;
2859 }
2860
2861 return true;
2862 } // end rewrite_cp_refs_in_type_annotation_struct()
2863
2864
2865 // Read, verify and skip over the target_type and target_info part
2866 // so that rewriting can continue in the later parts of the struct.
2867 //
2868 // u1 target_type;
2869 // union {
2870 // type_parameter_target;
2871 // supertype_target;
2872 // type_parameter_bound_target;
2873 // empty_target;
2874 // method_formal_parameter_target;
2875 // throws_target;
2876 // localvar_target;
2877 // catch_target;
2878 // offset_target;
2879 // type_argument_target;
2880 // } target_info;
2881 //
2882 bool VM_RedefineClasses::skip_type_annotation_target(
2883 AnnotationArray* type_annotations_typeArray, int &byte_i_ref,
2884 const char * location_mesg) {
2885
2886 if ((byte_i_ref + 1) > type_annotations_typeArray->length()) {
2887 // not enough room for a target_type let alone the rest of a type_annotation
2888 log_debug(redefine, class, annotation)("length() is too small for a target_type");
2889 return false;
2890 }
2891
2892 u1 target_type = type_annotations_typeArray->at(byte_i_ref);
2893 byte_i_ref += 1;
2894 log_debug(redefine, class, annotation)("target_type=0x%.2x", target_type);
2895 log_debug(redefine, class, annotation)("location=%s", location_mesg);
2896
2897 // Skip over target_info
2898 switch (target_type) {
2899 case 0x00:
2900 // kind: type parameter declaration of generic class or interface
2901 // location: ClassFile
2902 case 0x01:
2903 // kind: type parameter declaration of generic method or constructor
2904 // location: method_info
2905
2906 {
2907 // struct:
2908 // type_parameter_target {
2909 // u1 type_parameter_index;
2910 // }
2911 //
2912 if ((byte_i_ref + 1) > type_annotations_typeArray->length()) {
2913 log_debug(redefine, class, annotation)("length() is too small for a type_parameter_target");
2914 return false;
2915 }
2916
2917 u1 type_parameter_index = type_annotations_typeArray->at(byte_i_ref);
2918 byte_i_ref += 1;
2919
2920 log_debug(redefine, class, annotation)("type_parameter_target: type_parameter_index=%d", type_parameter_index);
2921 } break;
2922
2923 case 0x10:
2924 // kind: type in extends clause of class or interface declaration
2925 // or in implements clause of interface declaration
2926 // location: ClassFile
2927
2928 {
2929 // struct:
2930 // supertype_target {
2931 // u2 supertype_index;
2932 // }
2933 //
2934 if ((byte_i_ref + 2) > type_annotations_typeArray->length()) {
2935 log_debug(redefine, class, annotation)("length() is too small for a supertype_target");
2936 return false;
2937 }
2938
2939 u2 supertype_index = Bytes::get_Java_u2((address)
2940 type_annotations_typeArray->adr_at(byte_i_ref));
2941 byte_i_ref += 2;
2942
2943 log_debug(redefine, class, annotation)("supertype_target: supertype_index=%d", supertype_index);
2944 } break;
2945
2946 case 0x11:
2947 // kind: type in bound of type parameter declaration of generic class or interface
2948 // location: ClassFile
2949 case 0x12:
2950 // kind: type in bound of type parameter declaration of generic method or constructor
2951 // location: method_info
2952
2953 {
2954 // struct:
2955 // type_parameter_bound_target {
2956 // u1 type_parameter_index;
2957 // u1 bound_index;
2958 // }
2959 //
2960 if ((byte_i_ref + 2) > type_annotations_typeArray->length()) {
2961 log_debug(redefine, class, annotation)("length() is too small for a type_parameter_bound_target");
2962 return false;
2963 }
2964
2965 u1 type_parameter_index = type_annotations_typeArray->at(byte_i_ref);
2966 byte_i_ref += 1;
2967 u1 bound_index = type_annotations_typeArray->at(byte_i_ref);
2968 byte_i_ref += 1;
2969
2970 log_debug(redefine, class, annotation)
2971 ("type_parameter_bound_target: type_parameter_index=%d, bound_index=%d", type_parameter_index, bound_index);
2972 } break;
2973
2974 case 0x13:
2975 // kind: type in field declaration
2976 // location: field_info
2977 case 0x14:
2978 // kind: return type of method, or type of newly constructed object
2979 // location: method_info
2980 case 0x15:
2981 // kind: receiver type of method or constructor
2982 // location: method_info
2983
2984 {
2985 // struct:
2986 // empty_target {
2987 // }
2988 //
2989 log_debug(redefine, class, annotation)("empty_target");
2990 } break;
2991
2992 case 0x16:
2993 // kind: type in formal parameter declaration of method, constructor, or lambda expression
2994 // location: method_info
2995
2996 {
2997 // struct:
2998 // formal_parameter_target {
2999 // u1 formal_parameter_index;
3000 // }
3001 //
3002 if ((byte_i_ref + 1) > type_annotations_typeArray->length()) {
3003 log_debug(redefine, class, annotation)("length() is too small for a formal_parameter_target");
3004 return false;
3005 }
3006
3007 u1 formal_parameter_index = type_annotations_typeArray->at(byte_i_ref);
3008 byte_i_ref += 1;
3009
3010 log_debug(redefine, class, annotation)
3011 ("formal_parameter_target: formal_parameter_index=%d", formal_parameter_index);
3012 } break;
3013
3014 case 0x17:
3015 // kind: type in throws clause of method or constructor
3016 // location: method_info
3017
3018 {
3019 // struct:
3020 // throws_target {
3021 // u2 throws_type_index
3022 // }
3023 //
3024 if ((byte_i_ref + 2) > type_annotations_typeArray->length()) {
3025 log_debug(redefine, class, annotation)("length() is too small for a throws_target");
3026 return false;
3027 }
3028
3029 u2 throws_type_index = Bytes::get_Java_u2((address)
3030 type_annotations_typeArray->adr_at(byte_i_ref));
3031 byte_i_ref += 2;
3032
3033 log_debug(redefine, class, annotation)("throws_target: throws_type_index=%d", throws_type_index);
3034 } break;
3035
3036 case 0x40:
3037 // kind: type in local variable declaration
3038 // location: Code
3039 case 0x41:
3040 // kind: type in resource variable declaration
3041 // location: Code
3042
3043 {
3044 // struct:
3045 // localvar_target {
3046 // u2 table_length;
3047 // struct {
3048 // u2 start_pc;
3049 // u2 length;
3050 // u2 index;
3051 // } table[table_length];
3052 // }
3053 //
3054 if ((byte_i_ref + 2) > type_annotations_typeArray->length()) {
3055 // not enough room for a table_length let alone the rest of a localvar_target
3056 log_debug(redefine, class, annotation)("length() is too small for a localvar_target table_length");
3057 return false;
3058 }
3059
3060 u2 table_length = Bytes::get_Java_u2((address)
3061 type_annotations_typeArray->adr_at(byte_i_ref));
3062 byte_i_ref += 2;
3063
3064 log_debug(redefine, class, annotation)("localvar_target: table_length=%d", table_length);
3065
3066 int table_struct_size = 2 + 2 + 2; // 3 u2 variables per table entry
3067 int table_size = table_length * table_struct_size;
3068
3069 if ((byte_i_ref + table_size) > type_annotations_typeArray->length()) {
3070 // not enough room for a table
3071 log_debug(redefine, class, annotation)("length() is too small for a table array of length %d", table_length);
3072 return false;
3073 }
3074
3075 // Skip over table
3076 byte_i_ref += table_size;
3077 } break;
3078
3079 case 0x42:
3080 // kind: type in exception parameter declaration
3081 // location: Code
3082
3083 {
3084 // struct:
3085 // catch_target {
3086 // u2 exception_table_index;
3087 // }
3088 //
3089 if ((byte_i_ref + 2) > type_annotations_typeArray->length()) {
3090 log_debug(redefine, class, annotation)("length() is too small for a catch_target");
3091 return false;
3092 }
3093
3094 u2 exception_table_index = Bytes::get_Java_u2((address)
3095 type_annotations_typeArray->adr_at(byte_i_ref));
3096 byte_i_ref += 2;
3097
3098 log_debug(redefine, class, annotation)("catch_target: exception_table_index=%d", exception_table_index);
3099 } break;
3100
3101 case 0x43:
3102 // kind: type in instanceof expression
3103 // location: Code
3104 case 0x44:
3105 // kind: type in new expression
3106 // location: Code
3107 case 0x45:
3108 // kind: type in method reference expression using ::new
3109 // location: Code
3110 case 0x46:
3111 // kind: type in method reference expression using ::Identifier
3112 // location: Code
3113
3114 {
3115 // struct:
3116 // offset_target {
3117 // u2 offset;
3118 // }
3119 //
3120 if ((byte_i_ref + 2) > type_annotations_typeArray->length()) {
3121 log_debug(redefine, class, annotation)("length() is too small for a offset_target");
3122 return false;
3123 }
3124
3125 u2 offset = Bytes::get_Java_u2((address)
3126 type_annotations_typeArray->adr_at(byte_i_ref));
3127 byte_i_ref += 2;
3128
3129 log_debug(redefine, class, annotation)("offset_target: offset=%d", offset);
3130 } break;
3131
3132 case 0x47:
3133 // kind: type in cast expression
3134 // location: Code
3135 case 0x48:
3136 // kind: type argument for generic constructor in new expression or
3137 // explicit constructor invocation statement
3138 // location: Code
3139 case 0x49:
3140 // kind: type argument for generic method in method invocation expression
3141 // location: Code
3142 case 0x4A:
3143 // kind: type argument for generic constructor in method reference expression using ::new
3144 // location: Code
3145 case 0x4B:
3146 // kind: type argument for generic method in method reference expression using ::Identifier
3147 // location: Code
3148
3149 {
3150 // struct:
3151 // type_argument_target {
3152 // u2 offset;
3153 // u1 type_argument_index;
3154 // }
3155 //
3156 if ((byte_i_ref + 3) > type_annotations_typeArray->length()) {
3157 log_debug(redefine, class, annotation)("length() is too small for a type_argument_target");
3158 return false;
3159 }
3160
3161 u2 offset = Bytes::get_Java_u2((address)
3162 type_annotations_typeArray->adr_at(byte_i_ref));
3163 byte_i_ref += 2;
3164 u1 type_argument_index = type_annotations_typeArray->at(byte_i_ref);
3165 byte_i_ref += 1;
3166
3167 log_debug(redefine, class, annotation)
3168 ("type_argument_target: offset=%d, type_argument_index=%d", offset, type_argument_index);
3169 } break;
3170
3171 default:
3172 log_debug(redefine, class, annotation)("unknown target_type");
3173 #ifdef ASSERT
3174 ShouldNotReachHere();
3175 #endif
3176 return false;
3177 }
3178
3179 return true;
3180 } // end skip_type_annotation_target()
3181
3182
3183 // Read, verify and skip over the type_path part so that rewriting
3184 // can continue in the later parts of the struct.
3185 //
3186 // type_path {
3187 // u1 path_length;
3188 // {
3189 // u1 type_path_kind;
3190 // u1 type_argument_index;
3191 // } path[path_length];
3192 // }
3193 //
3194 bool VM_RedefineClasses::skip_type_annotation_type_path(
3195 AnnotationArray* type_annotations_typeArray, int &byte_i_ref) {
3196
3197 if ((byte_i_ref + 1) > type_annotations_typeArray->length()) {
3198 // not enough room for a path_length let alone the rest of the type_path
3199 log_debug(redefine, class, annotation)("length() is too small for a type_path");
3200 return false;
3201 }
3202
3203 u1 path_length = type_annotations_typeArray->at(byte_i_ref);
3204 byte_i_ref += 1;
3205
3206 log_debug(redefine, class, annotation)("type_path: path_length=%d", path_length);
3207
3208 int calc_path_length = 0;
3209 for (; calc_path_length < path_length; calc_path_length++) {
3210 if ((byte_i_ref + 1 + 1) > type_annotations_typeArray->length()) {
3211 // not enough room for a path
3212 log_debug(redefine, class, annotation)
3213 ("length() is too small for path entry %d of %d", calc_path_length, path_length);
3214 return false;
3215 }
3216
3217 u1 type_path_kind = type_annotations_typeArray->at(byte_i_ref);
3218 byte_i_ref += 1;
3219 u1 type_argument_index = type_annotations_typeArray->at(byte_i_ref);
3220 byte_i_ref += 1;
3221
3222 log_debug(redefine, class, annotation)
3223 ("type_path: path[%d]: type_path_kind=%d, type_argument_index=%d",
3224 calc_path_length, type_path_kind, type_argument_index);
3225
3226 if (type_path_kind > 3 || (type_path_kind != 3 && type_argument_index != 0)) {
3227 // not enough room for a path
3228 log_debug(redefine, class, annotation)("inconsistent type_path values");
3229 return false;
3230 }
3231 }
3232 assert(path_length == calc_path_length, "sanity check");
3233
3234 return true;
3235 } // end skip_type_annotation_type_path()
3236
3237
3238 // Rewrite constant pool references in the method's stackmap table.
3239 // These "structures" are adapted from the StackMapTable_attribute that
3240 // is described in section 4.8.4 of the 6.0 version of the VM spec
3241 // (dated 2005.10.26):
3242 // file:///net/quincunx.sfbay/export/gbracha/ClassFile-Java6.pdf
3243 //
3244 // stack_map {
3245 // u2 number_of_entries;
3246 // stack_map_frame entries[number_of_entries];
3247 // }
3248 //
3249 void VM_RedefineClasses::rewrite_cp_refs_in_stack_map_table(
3250 const methodHandle& method) {
3251
3252 if (!method->has_stackmap_table()) {
3253 return;
3254 }
3255
3256 AnnotationArray* stackmap_data = method->stackmap_data();
3257 address stackmap_p = (address)stackmap_data->adr_at(0);
3258 address stackmap_end = stackmap_p + stackmap_data->length();
3259
3260 assert(stackmap_p + 2 <= stackmap_end, "no room for number_of_entries");
3261 u2 number_of_entries = Bytes::get_Java_u2(stackmap_p);
3262 stackmap_p += 2;
3263
3264 log_debug(redefine, class, stackmap)("number_of_entries=%u", number_of_entries);
3265
3266 // walk through each stack_map_frame
3267 u2 calc_number_of_entries = 0;
3268 for (; calc_number_of_entries < number_of_entries; calc_number_of_entries++) {
3269 // The stack_map_frame structure is a u1 frame_type followed by
3270 // 0 or more bytes of data:
3271 //
3272 // union stack_map_frame {
3273 // same_frame;
3274 // same_locals_1_stack_item_frame;
3275 // same_locals_1_stack_item_frame_extended;
3276 // chop_frame;
3277 // same_frame_extended;
3278 // append_frame;
3279 // full_frame;
3280 // }
3281
3282 assert(stackmap_p + 1 <= stackmap_end, "no room for frame_type");
3283 u1 frame_type = *stackmap_p;
3284 stackmap_p++;
3285
3286 if (frame_type == 246) { // EARLY_LARVAL
3287 // rewrite_cp_refs in unset fields and fall through.
3288 rewrite_cp_refs_in_early_larval_stackmaps(stackmap_p, stackmap_end, calc_number_of_entries, frame_type);
3289 // The larval frames point to the next frame, so advance to the next frame and fall through.
3290 frame_type = *stackmap_p;
3291 stackmap_p++;
3292 }
3293
3294 // same_frame {
3295 // u1 frame_type = SAME; /* 0-63 */
3296 // }
3297 if (frame_type <= StackMapReader::SAME_FRAME_END) {
3298 // nothing more to do for same_frame
3299 }
3300
3301 // same_locals_1_stack_item_frame {
3302 // u1 frame_type = SAME_LOCALS_1_STACK_ITEM; /* 64-127 */
3303 // verification_type_info stack[1];
3304 // }
3305 else if (frame_type >= StackMapReader::SAME_LOCALS_1_STACK_ITEM_FRAME_START &&
3306 frame_type <= StackMapReader::SAME_LOCALS_1_STACK_ITEM_FRAME_END) {
3307 rewrite_cp_refs_in_verification_type_info(stackmap_p, stackmap_end,
3308 calc_number_of_entries, frame_type);
3309 }
3310
3311 // reserved for future use
3312 else if (frame_type >= StackMapReader::RESERVED_START &&
3313 frame_type <= StackMapReader::RESERVED_END) {
3314 // nothing more to do for reserved frame_types
3315 }
3316
3317 // same_locals_1_stack_item_frame_extended {
3318 // u1 frame_type = SAME_LOCALS_1_STACK_ITEM_EXTENDED; /* 247 */
3319 // u2 offset_delta;
3320 // verification_type_info stack[1];
3321 // }
3322 else if (frame_type == StackMapReader::SAME_LOCALS_1_STACK_ITEM_EXTENDED) {
3323 stackmap_p += 2;
3324 rewrite_cp_refs_in_verification_type_info(stackmap_p, stackmap_end,
3325 calc_number_of_entries, frame_type);
3326 }
3327
3328 // chop_frame {
3329 // u1 frame_type = CHOP; /* 248-250 */
3330 // u2 offset_delta;
3331 // }
3332 else if (frame_type >= StackMapReader::CHOP_FRAME_START &&
3333 frame_type <= StackMapReader::CHOP_FRAME_END) {
3334 stackmap_p += 2;
3335 }
3336
3337 // same_frame_extended {
3338 // u1 frame_type = SAME_EXTENDED; /* 251 */
3339 // u2 offset_delta;
3340 // }
3341 else if (frame_type == StackMapReader::SAME_FRAME_EXTENDED) {
3342 stackmap_p += 2;
3343 }
3344
3345 // append_frame {
3346 // u1 frame_type = APPEND; /* 252-254 */
3347 // u2 offset_delta;
3348 // verification_type_info locals[frame_type - SAME_EXTENDED];
3349 // }
3350 else if (frame_type >= StackMapReader::APPEND_FRAME_START &&
3351 frame_type <= StackMapReader::APPEND_FRAME_END) {
3352 assert(stackmap_p + 2 <= stackmap_end,
3353 "no room for offset_delta");
3354 stackmap_p += 2;
3355 u1 len = frame_type - StackMapReader::APPEND_FRAME_START + 1;
3356 for (u1 i = 0; i < len; i++) {
3357 rewrite_cp_refs_in_verification_type_info(stackmap_p, stackmap_end,
3358 calc_number_of_entries, frame_type);
3359 }
3360 }
3361
3362 // full_frame {
3363 // u1 frame_type = FULL_FRAME; /* 255 */
3364 // u2 offset_delta;
3365 // u2 number_of_locals;
3366 // verification_type_info locals[number_of_locals];
3367 // u2 number_of_stack_items;
3368 // verification_type_info stack[number_of_stack_items];
3369 // }
3370 else if (frame_type == StackMapReader::FULL_FRAME) {
3371 assert(stackmap_p + 2 + 2 <= stackmap_end,
3372 "no room for smallest full_frame");
3373 stackmap_p += 2;
3374
3375 u2 number_of_locals = Bytes::get_Java_u2(stackmap_p);
3376 stackmap_p += 2;
3377
3378 for (u2 locals_i = 0; locals_i < number_of_locals; locals_i++) {
3379 rewrite_cp_refs_in_verification_type_info(stackmap_p, stackmap_end,
3380 calc_number_of_entries, frame_type);
3381 }
3382
3383 // Use the largest size for the number_of_stack_items, but only get
3384 // the right number of bytes.
3385 u2 number_of_stack_items = Bytes::get_Java_u2(stackmap_p);
3386 stackmap_p += 2;
3387
3388 for (u2 stack_i = 0; stack_i < number_of_stack_items; stack_i++) {
3389 rewrite_cp_refs_in_verification_type_info(stackmap_p, stackmap_end,
3390 calc_number_of_entries, frame_type);
3391 }
3392 }
3393 } // end while there is a stack_map_frame
3394 assert(number_of_entries == calc_number_of_entries, "sanity check");
3395 } // end rewrite_cp_refs_in_stack_map_table()
3396
3397
3398 // Rewrite constant pool references in the verification type info
3399 // portion of the method's stackmap table. These "structures" are
3400 // adapted from the StackMapTable_attribute that is described in
3401 // section 4.8.4 of the 6.0 version of the VM spec (dated 2005.10.26):
3402 // file:///net/quincunx.sfbay/export/gbracha/ClassFile-Java6.pdf
3403 //
3404 // The verification_type_info structure is a u1 tag followed by 0 or
3405 // more bytes of data:
3406 //
3407 // union verification_type_info {
3408 // Top_variable_info;
3409 // Integer_variable_info;
3410 // Float_variable_info;
3411 // Long_variable_info;
3412 // Double_variable_info;
3413 // Null_variable_info;
3414 // UninitializedThis_variable_info;
3415 // Object_variable_info;
3416 // Uninitialized_variable_info;
3417 // }
3418 //
3419 void VM_RedefineClasses::rewrite_cp_refs_in_verification_type_info(
3420 address& stackmap_p_ref, address stackmap_end, u2 frame_i,
3421 u1 frame_type) {
3422
3423 assert(stackmap_p_ref + 1 <= stackmap_end, "no room for tag");
3424 u1 tag = *stackmap_p_ref;
3425 stackmap_p_ref++;
3426
3427 switch (tag) {
3428 // Top_variable_info {
3429 // u1 tag = ITEM_Top; /* 0 */
3430 // }
3431 // verificationType.hpp has zero as ITEM_Bogus instead of ITEM_Top
3432 case 0: // fall through
3433
3434 // Integer_variable_info {
3435 // u1 tag = ITEM_Integer; /* 1 */
3436 // }
3437 case ITEM_Integer: // fall through
3438
3439 // Float_variable_info {
3440 // u1 tag = ITEM_Float; /* 2 */
3441 // }
3442 case ITEM_Float: // fall through
3443
3444 // Double_variable_info {
3445 // u1 tag = ITEM_Double; /* 3 */
3446 // }
3447 case ITEM_Double: // fall through
3448
3449 // Long_variable_info {
3450 // u1 tag = ITEM_Long; /* 4 */
3451 // }
3452 case ITEM_Long: // fall through
3453
3454 // Null_variable_info {
3455 // u1 tag = ITEM_Null; /* 5 */
3456 // }
3457 case ITEM_Null: // fall through
3458
3459 // UninitializedThis_variable_info {
3460 // u1 tag = ITEM_UninitializedThis; /* 6 */
3461 // }
3462 case ITEM_UninitializedThis:
3463 // nothing more to do for the above tag types
3464 break;
3465
3466 // Object_variable_info {
3467 // u1 tag = ITEM_Object; /* 7 */
3468 // u2 cpool_index;
3469 // }
3470 case ITEM_Object:
3471 {
3472 assert(stackmap_p_ref + 2 <= stackmap_end, "no room for cpool_index");
3473 u2 cpool_index = Bytes::get_Java_u2(stackmap_p_ref);
3474 u2 new_cp_index = find_new_index(cpool_index);
3475 if (new_cp_index != 0) {
3476 log_debug(redefine, class, stackmap)("mapped old cpool_index=%d", cpool_index);
3477 Bytes::put_Java_u2(stackmap_p_ref, new_cp_index);
3478 cpool_index = new_cp_index;
3479 }
3480 stackmap_p_ref += 2;
3481
3482 log_debug(redefine, class, stackmap)
3483 ("frame_i=%u, frame_type=%u, cpool_index=%d", frame_i, frame_type, cpool_index);
3484 } break;
3485
3486 // Uninitialized_variable_info {
3487 // u1 tag = ITEM_Uninitialized; /* 8 */
3488 // u2 offset;
3489 // }
3490 case ITEM_Uninitialized:
3491 assert(stackmap_p_ref + 2 <= stackmap_end, "no room for offset");
3492 stackmap_p_ref += 2;
3493 break;
3494
3495 default:
3496 log_debug(redefine, class, stackmap)("frame_i=%u, frame_type=%u, bad tag=0x%x", frame_i, frame_type, tag);
3497 ShouldNotReachHere();
3498 break;
3499 } // end switch (tag)
3500 } // end rewrite_cp_refs_in_verification_type_info()
3501
3502
3503 void VM_RedefineClasses::rewrite_cp_refs_in_early_larval_stackmaps(
3504 address& stackmap_p_ref, address stackmap_end, u2 frame_i,
3505 u1 frame_type) {
3506
3507 u2 num_early_larval_stackmaps = Bytes::get_Java_u2(stackmap_p_ref);
3508 stackmap_p_ref += 2;
3509
3510 for (u2 i = 0; i < num_early_larval_stackmaps; i++) {
3511
3512 u2 name_and_ref_index = Bytes::get_Java_u2(stackmap_p_ref);
3513 u2 new_cp_index = find_new_index(name_and_ref_index);
3514 if (new_cp_index != 0) {
3515 log_debug(redefine, class, stackmap)("mapped old name_and_ref_index=%d", name_and_ref_index);
3516 Bytes::put_Java_u2(stackmap_p_ref, new_cp_index);
3517 name_and_ref_index = new_cp_index;
3518 }
3519 log_debug(redefine, class, stackmap)
3520 ("frame_i=%u, frame_type=%u, name_and_ref_index=%d", frame_i, frame_type, name_and_ref_index);
3521
3522 stackmap_p_ref += 2;
3523 }
3524 } // rewrite_cp_refs_in_early_larval_stackmaps
3525
3526 // Change the constant pool associated with klass scratch_class to scratch_cp.
3527 // scratch_cp_length elements are copied from scratch_cp to a smaller constant pool
3528 // and the smaller constant pool is associated with scratch_class.
3529 void VM_RedefineClasses::set_new_constant_pool(
3530 ClassLoaderData* loader_data,
3531 InstanceKlass* scratch_class, constantPoolHandle scratch_cp,
3532 int scratch_cp_length, TRAPS) {
3533 assert(scratch_cp->length() >= scratch_cp_length, "sanity check");
3534
3535 // scratch_cp is a merged constant pool and has enough space for a
3536 // worst case merge situation. We want to associate the minimum
3537 // sized constant pool with the klass to save space.
3538 ConstantPool* cp = ConstantPool::allocate(loader_data, scratch_cp_length, CHECK);
3539 constantPoolHandle smaller_cp(THREAD, cp);
3540
3541 // preserve version() value in the smaller copy
3542 int version = scratch_cp->version();
3543 assert(version != 0, "sanity check");
3544 smaller_cp->set_version(version);
3545
3546 // attach klass to new constant pool
3547 // reference to the cp holder is needed for copy_operands()
3548 smaller_cp->set_pool_holder(scratch_class);
3549
3550 smaller_cp->copy_fields(scratch_cp());
3551
3552 scratch_cp->copy_cp_to(1, scratch_cp_length - 1, smaller_cp, 1, THREAD);
3553 if (HAS_PENDING_EXCEPTION) {
3554 // Exception is handled in the caller
3555 loader_data->add_to_deallocate_list(smaller_cp());
3556 return;
3557 }
3558 scratch_cp = smaller_cp;
3559
3560 // attach new constant pool to klass
3561 scratch_class->set_constants(scratch_cp());
3562 scratch_cp->initialize_unresolved_klasses(loader_data, CHECK);
3563
3564 int i; // for portability
3565
3566 // update each field in klass to use new constant pool indices as needed
3567 int java_fields;
3568 int injected_fields;
3569 bool update_required = false;
3570 GrowableArray<FieldInfo>* fields = FieldInfoStream::create_FieldInfoArray(scratch_class->fieldinfo_stream(), &java_fields, &injected_fields);
3571 for (int i = 0; i < java_fields; i++) {
3572 FieldInfo* fi = fields->adr_at(i);
3573 jshort cur_index = fi->name_index();
3574 jshort new_index = find_new_index(cur_index);
3575 if (new_index != 0) {
3576 log_trace(redefine, class, constantpool)("field-name_index change: %d to %d", cur_index, new_index);
3577 fi->set_name_index(new_index);
3578 update_required = true;
3579 }
3580 cur_index = fi->signature_index();
3581 new_index = find_new_index(cur_index);
3582 if (new_index != 0) {
3583 log_trace(redefine, class, constantpool)("field-signature_index change: %d to %d", cur_index, new_index);
3584 fi->set_signature_index(new_index);
3585 update_required = true;
3586 }
3587 cur_index = fi->initializer_index();
3588 new_index = find_new_index(cur_index);
3589 if (new_index != 0) {
3590 log_trace(redefine, class, constantpool)("field-initval_index change: %d to %d", cur_index, new_index);
3591 fi->set_initializer_index(new_index);
3592 update_required = true;
3593 }
3594 cur_index = fi->generic_signature_index();
3595 new_index = find_new_index(cur_index);
3596 if (new_index != 0) {
3597 log_trace(redefine, class, constantpool)("field-generic_signature change: %d to %d", cur_index, new_index);
3598 fi->set_generic_signature_index(new_index);
3599 update_required = true;
3600 }
3601 }
3602 if (update_required) {
3603 Array<u1>* old_stream = scratch_class->fieldinfo_stream();
3604 assert(fields->length() == (java_fields + injected_fields), "Must be");
3605 Array<u1>* new_fis = FieldInfoStream::create_FieldInfoStream(fields, java_fields, injected_fields, scratch_class->class_loader_data(), CHECK);
3606 scratch_class->set_fieldinfo_stream(new_fis);
3607 MetadataFactory::free_array<u1>(scratch_class->class_loader_data(), old_stream);
3608
3609 Array<u1>* old_table = scratch_class->fieldinfo_search_table();
3610 Array<u1>* search_table = FieldInfoStream::create_search_table(scratch_class->constants(), new_fis, scratch_class->class_loader_data(), CHECK);
3611 scratch_class->set_fieldinfo_search_table(search_table);
3612 MetadataFactory::free_array<u1>(scratch_class->class_loader_data(), old_table);
3613
3614 DEBUG_ONLY(FieldInfoStream::validate_search_table(scratch_class->constants(), new_fis, search_table));
3615 }
3616
3617 // Update constant pool indices in the inner classes info to use
3618 // new constant indices as needed. The inner classes info is a
3619 // quadruple:
3620 // (inner_class_info, outer_class_info, inner_name, inner_access_flags)
3621 InnerClassesIterator iter(scratch_class);
3622 for (; !iter.done(); iter.next()) {
3623 int cur_index = iter.inner_class_info_index();
3624 if (cur_index == 0) {
3625 continue; // JVM spec. allows null inner class refs so skip it
3626 }
3627 u2 new_index = find_new_index(cur_index);
3628 if (new_index != 0) {
3629 log_trace(redefine, class, constantpool)("inner_class_info change: %d to %d", cur_index, new_index);
3630 iter.set_inner_class_info_index(new_index);
3631 }
3632 cur_index = iter.outer_class_info_index();
3633 new_index = find_new_index(cur_index);
3634 if (new_index != 0) {
3635 log_trace(redefine, class, constantpool)("outer_class_info change: %d to %d", cur_index, new_index);
3636 iter.set_outer_class_info_index(new_index);
3637 }
3638 cur_index = iter.inner_name_index();
3639 new_index = find_new_index(cur_index);
3640 if (new_index != 0) {
3641 log_trace(redefine, class, constantpool)("inner_name change: %d to %d", cur_index, new_index);
3642 iter.set_inner_name_index(new_index);
3643 }
3644 } // end for each inner class
3645
3646 // Attach each method in klass to the new constant pool and update
3647 // to use new constant pool indices as needed:
3648 Array<Method*>* methods = scratch_class->methods();
3649 for (i = methods->length() - 1; i >= 0; i--) {
3650 methodHandle method(THREAD, methods->at(i));
3651 method->set_constants(scratch_cp());
3652
3653 u2 new_index = find_new_index(method->name_index());
3654 if (new_index != 0) {
3655 log_trace(redefine, class, constantpool)
3656 ("method-name_index change: %d to %d", method->name_index(), new_index);
3657 method->set_name_index(new_index);
3658 }
3659 new_index = find_new_index(method->signature_index());
3660 if (new_index != 0) {
3661 log_trace(redefine, class, constantpool)
3662 ("method-signature_index change: %d to %d", method->signature_index(), new_index);
3663 method->set_signature_index(new_index);
3664 }
3665 new_index = find_new_index(method->generic_signature_index());
3666 if (new_index != 0) {
3667 log_trace(redefine, class, constantpool)
3668 ("method-generic_signature_index change: %d to %d", method->generic_signature_index(), new_index);
3669 method->constMethod()->set_generic_signature_index(new_index);
3670 }
3671
3672 // Update constant pool indices in the method's checked exception
3673 // table to use new constant indices as needed.
3674 int cext_length = method->checked_exceptions_length();
3675 if (cext_length > 0) {
3676 CheckedExceptionElement * cext_table =
3677 method->checked_exceptions_start();
3678 for (int j = 0; j < cext_length; j++) {
3679 int cur_index = cext_table[j].class_cp_index;
3680 int new_index = find_new_index(cur_index);
3681 if (new_index != 0) {
3682 log_trace(redefine, class, constantpool)("cext-class_cp_index change: %d to %d", cur_index, new_index);
3683 cext_table[j].class_cp_index = (u2)new_index;
3684 }
3685 } // end for each checked exception table entry
3686 } // end if there are checked exception table entries
3687
3688 // Update each catch type index in the method's exception table
3689 // to use new constant pool indices as needed. The exception table
3690 // holds quadruple entries of the form:
3691 // (beg_bci, end_bci, handler_bci, klass_index)
3692
3693 ExceptionTable ex_table(method());
3694 int ext_length = ex_table.length();
3695
3696 for (int j = 0; j < ext_length; j ++) {
3697 int cur_index = ex_table.catch_type_index(j);
3698 u2 new_index = find_new_index(cur_index);
3699 if (new_index != 0) {
3700 log_trace(redefine, class, constantpool)("ext-klass_index change: %d to %d", cur_index, new_index);
3701 ex_table.set_catch_type_index(j, new_index);
3702 }
3703 } // end for each exception table entry
3704
3705 // Update constant pool indices in the method's local variable
3706 // table to use new constant indices as needed. The local variable
3707 // table hold sextuple entries of the form:
3708 // (start_pc, length, name_index, descriptor_index, signature_index, slot)
3709 int lvt_length = method->localvariable_table_length();
3710 if (lvt_length > 0) {
3711 LocalVariableTableElement * lv_table =
3712 method->localvariable_table_start();
3713 for (int j = 0; j < lvt_length; j++) {
3714 int cur_index = lv_table[j].name_cp_index;
3715 int new_index = find_new_index(cur_index);
3716 if (new_index != 0) {
3717 log_trace(redefine, class, constantpool)("lvt-name_cp_index change: %d to %d", cur_index, new_index);
3718 lv_table[j].name_cp_index = (u2)new_index;
3719 }
3720 cur_index = lv_table[j].descriptor_cp_index;
3721 new_index = find_new_index(cur_index);
3722 if (new_index != 0) {
3723 log_trace(redefine, class, constantpool)("lvt-descriptor_cp_index change: %d to %d", cur_index, new_index);
3724 lv_table[j].descriptor_cp_index = (u2)new_index;
3725 }
3726 cur_index = lv_table[j].signature_cp_index;
3727 new_index = find_new_index(cur_index);
3728 if (new_index != 0) {
3729 log_trace(redefine, class, constantpool)("lvt-signature_cp_index change: %d to %d", cur_index, new_index);
3730 lv_table[j].signature_cp_index = (u2)new_index;
3731 }
3732 } // end for each local variable table entry
3733 } // end if there are local variable table entries
3734
3735 // Update constant pool indices in the method's method_parameters.
3736 int mp_length = method->method_parameters_length();
3737 if (mp_length > 0) {
3738 MethodParametersElement* elem = method->method_parameters_start();
3739 for (int j = 0; j < mp_length; j++) {
3740 const int cp_index = elem[j].name_cp_index;
3741 const int new_cp_index = find_new_index(cp_index);
3742 if (new_cp_index != 0) {
3743 elem[j].name_cp_index = (u2)new_cp_index;
3744 }
3745 }
3746 }
3747
3748 rewrite_cp_refs_in_stack_map_table(method);
3749 } // end for each method
3750 } // end set_new_constant_pool()
3751
3752
3753 // Unevolving classes may point to methods of the_class directly
3754 // from their constant pool caches, itables, and/or vtables. We
3755 // use the ClassLoaderDataGraph::classes_do() facility and this helper
3756 // to fix up these pointers. MethodData also points to old methods and
3757 // must be cleaned.
3758
3759 // Adjust cpools and vtables closure
3760 void VM_RedefineClasses::AdjustAndCleanMetadata::do_klass(Klass* k) {
3761
3762 // This is a very busy routine. We don't want too much tracing
3763 // printed out.
3764 bool trace_name_printed = false;
3765
3766 // If the class being redefined is java.lang.Object, we need to fix all
3767 // array class vtables also. The _has_redefined_Object flag is global.
3768 // Once the java.lang.Object has been redefined (by the current or one
3769 // of the previous VM_RedefineClasses operations) we have to always
3770 // adjust method entries for array classes.
3771 if (k->is_array_klass() && _has_redefined_Object) {
3772 k->vtable().adjust_method_entries(&trace_name_printed);
3773
3774 } else if (k->is_instance_klass()) {
3775 HandleMark hm(_thread);
3776 InstanceKlass *ik = InstanceKlass::cast(k);
3777
3778 // Clean MethodData of this class's methods so they don't refer to
3779 // old methods that are no longer running.
3780 Array<Method*>* methods = ik->methods();
3781 int num_methods = methods->length();
3782 for (int index = 0; index < num_methods; ++index) {
3783 if (methods->at(index)->method_data() != nullptr) {
3784 methods->at(index)->method_data()->clean_weak_method_links();
3785 }
3786 }
3787
3788 // Adjust all vtables, default methods and itables, to clean out old methods.
3789 ResourceMark rm(_thread);
3790 if (ik->vtable_length() > 0) {
3791 ik->vtable().adjust_method_entries(&trace_name_printed);
3792 ik->adjust_default_methods(&trace_name_printed);
3793 }
3794
3795 if (ik->itable_length() > 0) {
3796 ik->itable().adjust_method_entries(&trace_name_printed);
3797 }
3798
3799 // The constant pools in other classes (other_cp) can refer to
3800 // old methods. We have to update method information in
3801 // other_cp's cache. If other_cp has a previous version, then we
3802 // have to repeat the process for each previous version. The
3803 // constant pool cache holds the Method*s for non-virtual
3804 // methods and for virtual, final methods.
3805 //
3806 // Special case: if the current class is being redefined by the current
3807 // VM_RedefineClasses operation, then new_cp has already been attached
3808 // to the_class and old_cp has already been added as a previous version.
3809 // The new_cp doesn't have any cached references to old methods so it
3810 // doesn't need to be updated and we could optimize by skipping it.
3811 // However, the current class can be marked as being redefined by another
3812 // VM_RedefineClasses operation which has already executed its doit_prologue
3813 // and needs cpcache method entries adjusted. For simplicity, the cpcache
3814 // update is done unconditionally. It should result in doing nothing for
3815 // classes being redefined by the current VM_RedefineClasses operation.
3816 // Method entries in the previous version(s) are adjusted as well.
3817 ConstantPoolCache* cp_cache;
3818
3819 // this klass' constant pool cache may need adjustment
3820 ConstantPool* other_cp = ik->constants();
3821 cp_cache = other_cp->cache();
3822 if (cp_cache != nullptr) {
3823 cp_cache->adjust_method_entries(&trace_name_printed);
3824 }
3825
3826 // the previous versions' constant pool caches may need adjustment
3827 for (InstanceKlass* pv_node = ik->previous_versions();
3828 pv_node != nullptr;
3829 pv_node = pv_node->previous_versions()) {
3830 cp_cache = pv_node->constants()->cache();
3831 if (cp_cache != nullptr) {
3832 cp_cache->adjust_method_entries(&trace_name_printed);
3833 }
3834 }
3835 }
3836 }
3837
3838 void VM_RedefineClasses::update_jmethod_ids() {
3839 for (int j = 0; j < _matching_methods_length; ++j) {
3840 Method* old_method = _matching_old_methods[j];
3841 // The method_idnum should be within the range of 1..number-of-methods
3842 // until incremented later for obsolete methods.
3843 // The increment is so if a jmethodID is created for an old obsolete method
3844 // it gets a new jmethodID cache slot in the InstanceKlass.
3845 // They're cleaned out later when all methods of the previous version are purged.
3846 assert(old_method->method_idnum() <= _old_methods->length(),
3847 "shouldn't be incremented yet for obsolete methods");
3848 jmethodID jmid = old_method->find_jmethod_id_or_null();
3849 if (jmid != nullptr) {
3850 // There is a jmethodID, change it to point to the new method
3851 Method* new_method = _matching_new_methods[j];
3852 Method::change_method_associated_with_jmethod_id(jmid, new_method);
3853 assert(Method::resolve_jmethod_id(jmid) == _matching_new_methods[j],
3854 "should be replaced");
3855 }
3856 }
3857 }
3858
3859 int VM_RedefineClasses::check_methods_and_mark_as_obsolete() {
3860 int emcp_method_count = 0;
3861 int obsolete_count = 0;
3862 int old_index = 0;
3863 for (int j = 0; j < _matching_methods_length; ++j, ++old_index) {
3864 Method* old_method = _matching_old_methods[j];
3865 Method* new_method = _matching_new_methods[j];
3866 Method* old_array_method;
3867
3868 // Maintain an old_index into the _old_methods array by skipping
3869 // deleted methods
3870 while ((old_array_method = _old_methods->at(old_index)) != old_method) {
3871 ++old_index;
3872 }
3873
3874 if (MethodComparator::methods_EMCP(old_method, new_method)) {
3875 // The EMCP definition from JSR-163 requires the bytecodes to be
3876 // the same with the exception of constant pool indices which may
3877 // differ. However, the constants referred to by those indices
3878 // must be the same.
3879 //
3880 // We use methods_EMCP() for comparison since constant pool
3881 // merging can remove duplicate constant pool entries that were
3882 // present in the old method and removed from the rewritten new
3883 // method. A faster binary comparison function would consider the
3884 // old and new methods to be different when they are actually
3885 // EMCP.
3886 //
3887 // The old and new methods are EMCP and you would think that we
3888 // could get rid of one of them here and now and save some space.
3889 // However, the concept of EMCP only considers the bytecodes and
3890 // the constant pool entries in the comparison. Other things,
3891 // e.g., the line number table (LNT) or the local variable table
3892 // (LVT) don't count in the comparison. So the new (and EMCP)
3893 // method can have a new LNT that we need so we can't just
3894 // overwrite the new method with the old method.
3895 //
3896 // When this routine is called, we have already attached the new
3897 // methods to the_class so the old methods are effectively
3898 // overwritten. However, if an old method is still executing,
3899 // then the old method cannot be collected until sometime after
3900 // the old method call has returned. So the overwriting of old
3901 // methods by new methods will save us space except for those
3902 // (hopefully few) old methods that are still executing.
3903 //
3904 // A method refers to a ConstMethod* and this presents another
3905 // possible avenue to space savings. The ConstMethod* in the
3906 // new method contains possibly new attributes (LNT, LVT, etc).
3907 // At first glance, it seems possible to save space by replacing
3908 // the ConstMethod* in the old method with the ConstMethod*
3909 // from the new method. The old and new methods would share the
3910 // same ConstMethod* and we would save the space occupied by
3911 // the old ConstMethod*. However, the ConstMethod* contains
3912 // a back reference to the containing method. Sharing the
3913 // ConstMethod* between two methods could lead to confusion in
3914 // the code that uses the back reference. This would lead to
3915 // brittle code that could be broken in non-obvious ways now or
3916 // in the future.
3917 //
3918 // Another possibility is to copy the ConstMethod* from the new
3919 // method to the old method and then overwrite the new method with
3920 // the old method. Since the ConstMethod* contains the bytecodes
3921 // for the method embedded in the oop, this option would change
3922 // the bytecodes out from under any threads executing the old
3923 // method and make the thread's bcp invalid. Since EMCP requires
3924 // that the bytecodes be the same modulo constant pool indices, it
3925 // is straight forward to compute the correct new bcp in the new
3926 // ConstMethod* from the old bcp in the old ConstMethod*. The
3927 // time consuming part would be searching all the frames in all
3928 // of the threads to find all of the calls to the old method.
3929 //
3930 // It looks like we will have to live with the limited savings
3931 // that we get from effectively overwriting the old methods
3932 // when the new methods are attached to the_class.
3933
3934 // Count number of methods that are EMCP. The method will be marked
3935 // old but not obsolete if it is EMCP.
3936 emcp_method_count++;
3937
3938 // An EMCP method is _not_ obsolete. An obsolete method has a
3939 // different jmethodID than the current method. An EMCP method
3940 // has the same jmethodID as the current method. Having the
3941 // same jmethodID for all EMCP versions of a method allows for
3942 // a consistent view of the EMCP methods regardless of which
3943 // EMCP method you happen to have in hand. For example, a
3944 // breakpoint set in one EMCP method will work for all EMCP
3945 // versions of the method including the current one.
3946 } else {
3947 // mark obsolete methods as such
3948 old_method->set_is_obsolete();
3949 obsolete_count++;
3950
3951 // obsolete methods need a unique idnum so they become new entries in
3952 // the jmethodID cache in InstanceKlass
3953 assert(old_method->method_idnum() == new_method->method_idnum(), "must match");
3954 u2 num = InstanceKlass::cast(_the_class)->next_method_idnum();
3955 if (num != ConstMethod::UNSET_IDNUM) {
3956 old_method->set_method_idnum(num);
3957 }
3958
3959 // With tracing we try not to "yack" too much. The position of
3960 // this trace assumes there are fewer obsolete methods than
3961 // EMCP methods.
3962 if (log_is_enabled(Trace, redefine, class, obsolete, mark)) {
3963 ResourceMark rm;
3964 log_trace(redefine, class, obsolete, mark)
3965 ("mark %s(%s) as obsolete", old_method->name()->as_C_string(), old_method->signature()->as_C_string());
3966 }
3967 }
3968 old_method->set_is_old();
3969 }
3970 for (int i = 0; i < _deleted_methods_length; ++i) {
3971 Method* old_method = _deleted_methods[i];
3972
3973 assert(!old_method->has_vtable_index(),
3974 "cannot delete methods with vtable entries");;
3975
3976 // Mark all deleted methods as old, obsolete and deleted
3977 old_method->set_is_deleted();
3978 old_method->set_is_old();
3979 old_method->set_is_obsolete();
3980 ++obsolete_count;
3981 // With tracing we try not to "yack" too much. The position of
3982 // this trace assumes there are fewer obsolete methods than
3983 // EMCP methods.
3984 if (log_is_enabled(Trace, redefine, class, obsolete, mark)) {
3985 ResourceMark rm;
3986 log_trace(redefine, class, obsolete, mark)
3987 ("mark deleted %s(%s) as obsolete", old_method->name()->as_C_string(), old_method->signature()->as_C_string());
3988 }
3989 }
3990 assert((emcp_method_count + obsolete_count) == _old_methods->length(),
3991 "sanity check");
3992 log_trace(redefine, class, obsolete, mark)("EMCP_cnt=%d, obsolete_cnt=%d", emcp_method_count, obsolete_count);
3993 return emcp_method_count;
3994 }
3995
3996 // This internal class transfers the native function registration from old methods
3997 // to new methods. It is designed to handle both the simple case of unchanged
3998 // native methods and the complex cases of native method prefixes being added and/or
3999 // removed.
4000 // It expects only to be used during the VM_RedefineClasses op (a safepoint).
4001 //
4002 // This class is used after the new methods have been installed in "the_class".
4003 //
4004 // So, for example, the following must be handled. Where 'm' is a method and
4005 // a number followed by an underscore is a prefix.
4006 //
4007 // Old Name New Name
4008 // Simple transfer to new method m -> m
4009 // Add prefix m -> 1_m
4010 // Remove prefix 1_m -> m
4011 // Simultaneous add of prefixes m -> 3_2_1_m
4012 // Simultaneous removal of prefixes 3_2_1_m -> m
4013 // Simultaneous add and remove 1_m -> 2_m
4014 // Same, caused by prefix removal only 3_2_1_m -> 3_2_m
4015 //
4016 class TransferNativeFunctionRegistration {
4017 private:
4018 InstanceKlass* the_class;
4019 int prefix_count;
4020 char** prefixes;
4021
4022 // Recursively search the binary tree of possibly prefixed method names.
4023 // Iteration could be used if all agents were well behaved. Full tree walk is
4024 // more resilent to agents not cleaning up intermediate methods.
4025 // Branch at each depth in the binary tree is:
4026 // (1) without the prefix.
4027 // (2) with the prefix.
4028 // where 'prefix' is the prefix at that 'depth' (first prefix, second prefix,...)
4029 Method* search_prefix_name_space(int depth, char* name_str, size_t name_len,
4030 Symbol* signature) {
4031 TempNewSymbol name_symbol = SymbolTable::probe(name_str, (int)name_len);
4032 if (name_symbol != nullptr) {
4033 Method* method = the_class->lookup_method(name_symbol, signature);
4034 if (method != nullptr) {
4035 // Even if prefixed, intermediate methods must exist.
4036 if (method->is_native()) {
4037 // Wahoo, we found a (possibly prefixed) version of the method, return it.
4038 return method;
4039 }
4040 if (depth < prefix_count) {
4041 // Try applying further prefixes (other than this one).
4042 method = search_prefix_name_space(depth+1, name_str, name_len, signature);
4043 if (method != nullptr) {
4044 return method; // found
4045 }
4046
4047 // Try adding this prefix to the method name and see if it matches
4048 // another method name.
4049 char* prefix = prefixes[depth];
4050 size_t prefix_len = strlen(prefix);
4051 size_t trial_len = name_len + prefix_len;
4052 char* trial_name_str = NEW_RESOURCE_ARRAY(char, trial_len + 1);
4053 strcpy(trial_name_str, prefix);
4054 strcat(trial_name_str, name_str);
4055 method = search_prefix_name_space(depth+1, trial_name_str, trial_len,
4056 signature);
4057 if (method != nullptr) {
4058 // If found along this branch, it was prefixed, mark as such
4059 method->set_is_prefixed_native();
4060 return method; // found
4061 }
4062 }
4063 }
4064 }
4065 return nullptr; // This whole branch bore nothing
4066 }
4067
4068 // Return the method name with old prefixes stripped away.
4069 char* method_name_without_prefixes(Method* method) {
4070 Symbol* name = method->name();
4071 char* name_str = name->as_utf8();
4072
4073 // Old prefixing may be defunct, strip prefixes, if any.
4074 for (int i = prefix_count-1; i >= 0; i--) {
4075 char* prefix = prefixes[i];
4076 size_t prefix_len = strlen(prefix);
4077 if (strncmp(prefix, name_str, prefix_len) == 0) {
4078 name_str += prefix_len;
4079 }
4080 }
4081 return name_str;
4082 }
4083
4084 // Strip any prefixes off the old native method, then try to find a
4085 // (possibly prefixed) new native that matches it.
4086 Method* strip_and_search_for_new_native(Method* method) {
4087 ResourceMark rm;
4088 char* name_str = method_name_without_prefixes(method);
4089 return search_prefix_name_space(0, name_str, strlen(name_str),
4090 method->signature());
4091 }
4092
4093 public:
4094
4095 // Construct a native method transfer processor for this class.
4096 TransferNativeFunctionRegistration(InstanceKlass* _the_class) {
4097 assert(SafepointSynchronize::is_at_safepoint(), "sanity check");
4098
4099 the_class = _the_class;
4100 prefixes = JvmtiExport::get_all_native_method_prefixes(&prefix_count);
4101 }
4102
4103 // Attempt to transfer any of the old or deleted methods that are native
4104 void transfer_registrations(Method** old_methods, int methods_length) {
4105 for (int j = 0; j < methods_length; j++) {
4106 Method* old_method = old_methods[j];
4107
4108 if (old_method->is_native() && old_method->has_native_function()) {
4109 Method* new_method = strip_and_search_for_new_native(old_method);
4110 if (new_method != nullptr) {
4111 // Actually set the native function in the new method.
4112 // Redefine does not send events (except CFLH), certainly not this
4113 // behind the scenes re-registration.
4114 new_method->set_native_function(old_method->native_function(),
4115 !Method::native_bind_event_is_interesting);
4116 }
4117 }
4118 }
4119 }
4120 };
4121
4122 // Don't lose the association between a native method and its JNI function.
4123 void VM_RedefineClasses::transfer_old_native_function_registrations(InstanceKlass* the_class) {
4124 TransferNativeFunctionRegistration transfer(the_class);
4125 transfer.transfer_registrations(_deleted_methods, _deleted_methods_length);
4126 transfer.transfer_registrations(_matching_old_methods, _matching_methods_length);
4127 }
4128
4129 // Deoptimize all compiled code that depends on the classes redefined.
4130 //
4131 // If the can_redefine_classes capability is obtained in the onload
4132 // phase or 'AlwaysRecordEvolDependencies' is true, then the compiler has
4133 // recorded all dependencies from startup. In that case we need only
4134 // deoptimize and throw away all compiled code that depends on the class.
4135 //
4136 // If can_redefine_classes is obtained sometime after the onload phase
4137 // (and 'AlwaysRecordEvolDependencies' is false) then the dependency
4138 // information may be incomplete. In that case the first call to
4139 // RedefineClasses causes all compiled code to be thrown away. As
4140 // can_redefine_classes has been obtained then all future compilations will
4141 // record dependencies so second and subsequent calls to RedefineClasses
4142 // need only throw away code that depends on the class.
4143 //
4144
4145 void VM_RedefineClasses::flush_dependent_code() {
4146 assert(SafepointSynchronize::is_at_safepoint(), "sanity check");
4147 assert(JvmtiExport::all_dependencies_are_recorded() || !AlwaysRecordEvolDependencies, "sanity check");
4148
4149 DeoptimizationScope deopt_scope;
4150
4151 // This is the first redefinition, mark all the nmethods for deoptimization
4152 if (!JvmtiExport::all_dependencies_are_recorded()) {
4153 CodeCache::mark_all_nmethods_for_evol_deoptimization(&deopt_scope);
4154 log_debug(redefine, class, nmethod)("Marked all nmethods for deopt");
4155 } else {
4156 CodeCache::mark_dependents_for_evol_deoptimization(&deopt_scope);
4157 log_debug(redefine, class, nmethod)("Marked dependent nmethods for deopt");
4158 }
4159
4160 deopt_scope.deoptimize_marked();
4161
4162 // From now on we know that the dependency information is complete
4163 JvmtiExport::set_all_dependencies_are_recorded(true);
4164 }
4165
4166 void VM_RedefineClasses::compute_added_deleted_matching_methods() {
4167 Method* old_method;
4168 Method* new_method;
4169
4170 _matching_old_methods = NEW_RESOURCE_ARRAY(Method*, _old_methods->length());
4171 _matching_new_methods = NEW_RESOURCE_ARRAY(Method*, _old_methods->length());
4172 _added_methods = NEW_RESOURCE_ARRAY(Method*, _new_methods->length());
4173 _deleted_methods = NEW_RESOURCE_ARRAY(Method*, _old_methods->length());
4174
4175 _matching_methods_length = 0;
4176 _deleted_methods_length = 0;
4177 _added_methods_length = 0;
4178
4179 int nj = 0;
4180 int oj = 0;
4181 while (true) {
4182 if (oj >= _old_methods->length()) {
4183 if (nj >= _new_methods->length()) {
4184 break; // we've looked at everything, done
4185 }
4186 // New method at the end
4187 new_method = _new_methods->at(nj);
4188 _added_methods[_added_methods_length++] = new_method;
4189 ++nj;
4190 } else if (nj >= _new_methods->length()) {
4191 // Old method, at the end, is deleted
4192 old_method = _old_methods->at(oj);
4193 _deleted_methods[_deleted_methods_length++] = old_method;
4194 ++oj;
4195 } else {
4196 old_method = _old_methods->at(oj);
4197 new_method = _new_methods->at(nj);
4198 if (old_method->name() == new_method->name()) {
4199 if (old_method->signature() == new_method->signature()) {
4200 _matching_old_methods[_matching_methods_length ] = old_method;
4201 _matching_new_methods[_matching_methods_length++] = new_method;
4202 ++nj;
4203 ++oj;
4204 } else {
4205 // added overloaded have already been moved to the end,
4206 // so this is a deleted overloaded method
4207 _deleted_methods[_deleted_methods_length++] = old_method;
4208 ++oj;
4209 }
4210 } else { // names don't match
4211 if (old_method->name()->fast_compare(new_method->name()) > 0) {
4212 // new method
4213 _added_methods[_added_methods_length++] = new_method;
4214 ++nj;
4215 } else {
4216 // deleted method
4217 _deleted_methods[_deleted_methods_length++] = old_method;
4218 ++oj;
4219 }
4220 }
4221 }
4222 }
4223 assert(_matching_methods_length + _deleted_methods_length == _old_methods->length(), "sanity");
4224 assert(_matching_methods_length + _added_methods_length == _new_methods->length(), "sanity");
4225 }
4226
4227
4228 void VM_RedefineClasses::swap_annotations(InstanceKlass* the_class,
4229 InstanceKlass* scratch_class) {
4230 // Swap annotation fields values
4231 Annotations* old_annotations = the_class->annotations();
4232 the_class->set_annotations(scratch_class->annotations());
4233 scratch_class->set_annotations(old_annotations);
4234 }
4235
4236
4237 // Install the redefinition of a class:
4238 // - house keeping (flushing breakpoints and caches, deoptimizing
4239 // dependent compiled code)
4240 // - replacing parts in the_class with parts from scratch_class
4241 // - adding a weak reference to track the obsolete but interesting
4242 // parts of the_class
4243 // - adjusting constant pool caches and vtables in other classes
4244 // that refer to methods in the_class. These adjustments use the
4245 // ClassLoaderDataGraph::classes_do() facility which only allows
4246 // a helper method to be specified. The interesting parameters
4247 // that we would like to pass to the helper method are saved in
4248 // static global fields in the VM operation.
4249 void VM_RedefineClasses::redefine_single_class(Thread* current, jclass the_jclass,
4250 InstanceKlass* scratch_class) {
4251
4252 HandleMark hm(current); // make sure handles from this call are freed
4253
4254 if (log_is_enabled(Info, redefine, class, timer)) {
4255 _timer_rsc_phase1.start();
4256 }
4257
4258 InstanceKlass* the_class = get_ik(the_jclass);
4259
4260 // Set a flag to control and optimize adjusting method entries
4261 _has_redefined_Object |= the_class == vmClasses::Object_klass();
4262
4263 // Remove all breakpoints in methods of this class
4264 JvmtiBreakpoints& jvmti_breakpoints = JvmtiCurrentBreakpoints::get_jvmti_breakpoints();
4265 jvmti_breakpoints.clearall_in_class_at_safepoint(the_class);
4266
4267 _old_methods = the_class->methods();
4268 _new_methods = scratch_class->methods();
4269 _the_class = the_class;
4270 compute_added_deleted_matching_methods();
4271 update_jmethod_ids();
4272
4273 _any_class_has_resolved_methods = the_class->has_resolved_methods() || _any_class_has_resolved_methods;
4274
4275 // Attach new constant pool to the original klass. The original
4276 // klass still refers to the old constant pool (for now).
4277 scratch_class->constants()->set_pool_holder(the_class);
4278
4279 #if 0
4280 // In theory, with constant pool merging in place we should be able
4281 // to save space by using the new, merged constant pool in place of
4282 // the old constant pool(s). By "pool(s)" I mean the constant pool in
4283 // the klass version we are replacing now and any constant pool(s) in
4284 // previous versions of klass. Nice theory, doesn't work in practice.
4285 // When this code is enabled, even simple programs throw NullPointer
4286 // exceptions. I'm guessing that this is caused by some constant pool
4287 // cache difference between the new, merged constant pool and the
4288 // constant pool that was just being used by the klass. I'm keeping
4289 // this code around to archive the idea, but the code has to remain
4290 // disabled for now.
4291
4292 // Attach each old method to the new constant pool. This can be
4293 // done here since we are past the bytecode verification and
4294 // constant pool optimization phases.
4295 for (int i = _old_methods->length() - 1; i >= 0; i--) {
4296 Method* method = _old_methods->at(i);
4297 method->set_constants(scratch_class->constants());
4298 }
4299
4300 // NOTE: this doesn't work because you can redefine the same class in two
4301 // threads, each getting their own constant pool data appended to the
4302 // original constant pool. In order for the new methods to work when they
4303 // become old methods, they need to keep their updated copy of the constant pool.
4304
4305 {
4306 // walk all previous versions of the klass
4307 InstanceKlass *ik = the_class;
4308 PreviousVersionWalker pvw(ik);
4309 do {
4310 ik = pvw.next_previous_version();
4311 if (ik != nullptr) {
4312
4313 // attach previous version of klass to the new constant pool
4314 ik->set_constants(scratch_class->constants());
4315
4316 // Attach each method in the previous version of klass to the
4317 // new constant pool
4318 Array<Method*>* prev_methods = ik->methods();
4319 for (int i = prev_methods->length() - 1; i >= 0; i--) {
4320 Method* method = prev_methods->at(i);
4321 method->set_constants(scratch_class->constants());
4322 }
4323 }
4324 } while (ik != nullptr);
4325 }
4326 #endif
4327
4328 // Replace methods and constantpool
4329 the_class->set_methods(_new_methods);
4330 scratch_class->set_methods(_old_methods); // To prevent potential GCing of the old methods,
4331 // and to be able to undo operation easily.
4332
4333 Array<int>* old_ordering = the_class->method_ordering();
4334 the_class->set_method_ordering(scratch_class->method_ordering());
4335 scratch_class->set_method_ordering(old_ordering);
4336
4337 ConstantPool* old_constants = the_class->constants();
4338 the_class->set_constants(scratch_class->constants());
4339 scratch_class->set_constants(old_constants); // See the previous comment.
4340 #if 0
4341 // We are swapping the guts of "the new class" with the guts of "the
4342 // class". Since the old constant pool has just been attached to "the
4343 // new class", it seems logical to set the pool holder in the old
4344 // constant pool also. However, doing this will change the observable
4345 // class hierarchy for any old methods that are still executing. A
4346 // method can query the identity of its "holder" and this query uses
4347 // the method's constant pool link to find the holder. The change in
4348 // holding class from "the class" to "the new class" can confuse
4349 // things.
4350 //
4351 // Setting the old constant pool's holder will also cause
4352 // verification done during vtable initialization below to fail.
4353 // During vtable initialization, the vtable's class is verified to be
4354 // a subtype of the method's holder. The vtable's class is "the
4355 // class" and the method's holder is gotten from the constant pool
4356 // link in the method itself. For "the class"'s directly implemented
4357 // methods, the method holder is "the class" itself (as gotten from
4358 // the new constant pool). The check works fine in this case. The
4359 // check also works fine for methods inherited from super classes.
4360 //
4361 // Miranda methods are a little more complicated. A miranda method is
4362 // provided by an interface when the class implementing the interface
4363 // does not provide its own method. These interfaces are implemented
4364 // internally as an InstanceKlass. These special instanceKlasses
4365 // share the constant pool of the class that "implements" the
4366 // interface. By sharing the constant pool, the method holder of a
4367 // miranda method is the class that "implements" the interface. In a
4368 // non-redefine situation, the subtype check works fine. However, if
4369 // the old constant pool's pool holder is modified, then the check
4370 // fails because there is no class hierarchy relationship between the
4371 // vtable's class and "the new class".
4372
4373 old_constants->set_pool_holder(scratch_class());
4374 #endif
4375
4376 // track number of methods that are EMCP for add_previous_version() call below
4377 int emcp_method_count = check_methods_and_mark_as_obsolete();
4378 transfer_old_native_function_registrations(the_class);
4379
4380 if (scratch_class->get_cached_class_file() != the_class->get_cached_class_file()) {
4381 // 1. the_class doesn't have a cache yet, scratch_class does have a cache.
4382 // 2. The same class can be present twice in the scratch classes list or there
4383 // are multiple concurrent RetransformClasses calls on different threads.
4384 // the_class and scratch_class have the same cached bytes, but different buffers.
4385 // In such cases we need to deallocate one of the buffers.
4386 // 3. RedefineClasses and the_class has cached bytes from a previous transformation.
4387 // In the case we need to use class bytes from scratch_class.
4388 if (the_class->get_cached_class_file() != nullptr) {
4389 os::free(the_class->get_cached_class_file());
4390 }
4391 the_class->set_cached_class_file(scratch_class->get_cached_class_file());
4392 }
4393
4394 // null out in scratch class to not delete twice. The class to be redefined
4395 // always owns these bytes.
4396 scratch_class->set_cached_class_file(nullptr);
4397
4398 // Replace inner_classes
4399 Array<u2>* old_inner_classes = the_class->inner_classes();
4400 the_class->set_inner_classes(scratch_class->inner_classes());
4401 scratch_class->set_inner_classes(old_inner_classes);
4402
4403 // Initialize the vtable and interface table after
4404 // methods have been rewritten
4405 // no exception should happen here since we explicitly
4406 // do not check loader constraints.
4407 // compare_and_normalize_class_versions has already checked:
4408 // - classloaders unchanged, signatures unchanged
4409 // - all instanceKlasses for redefined classes reused & contents updated
4410 the_class->vtable().initialize_vtable();
4411 the_class->itable().initialize_itable();
4412
4413 // Update jmethodID cache if present.
4414 the_class->update_methods_jmethod_cache();
4415
4416 // Copy the "source debug extension" attribute from new class version
4417 the_class->set_source_debug_extension(
4418 scratch_class->source_debug_extension(),
4419 scratch_class->source_debug_extension() == nullptr ? 0 :
4420 (int)strlen(scratch_class->source_debug_extension()));
4421
4422 // Use of javac -g could be different in the old and the new
4423 if (scratch_class->has_localvariable_table() !=
4424 the_class->has_localvariable_table()) {
4425 the_class->set_has_localvariable_table(scratch_class->has_localvariable_table());
4426 }
4427
4428 swap_annotations(the_class, scratch_class);
4429
4430 // Replace minor version number of class file
4431 u2 old_minor_version = the_class->constants()->minor_version();
4432 the_class->constants()->set_minor_version(scratch_class->constants()->minor_version());
4433 scratch_class->constants()->set_minor_version(old_minor_version);
4434
4435 // Replace major version number of class file
4436 u2 old_major_version = the_class->constants()->major_version();
4437 the_class->constants()->set_major_version(scratch_class->constants()->major_version());
4438 scratch_class->constants()->set_major_version(old_major_version);
4439
4440 // Replace CP indexes for class and name+type of enclosing method
4441 u2 old_class_idx = the_class->enclosing_method_class_index();
4442 u2 old_method_idx = the_class->enclosing_method_method_index();
4443 the_class->set_enclosing_method_indices(
4444 scratch_class->enclosing_method_class_index(),
4445 scratch_class->enclosing_method_method_index());
4446 scratch_class->set_enclosing_method_indices(old_class_idx, old_method_idx);
4447
4448 if (!the_class->has_been_redefined()) {
4449 the_class->set_has_been_redefined();
4450 }
4451
4452 // Scratch class is unloaded but still needs cleaning, and skipping for CDS.
4453 scratch_class->set_is_scratch_class();
4454
4455 // keep track of previous versions of this class
4456 the_class->add_previous_version(scratch_class, emcp_method_count);
4457
4458 JFR_ONLY(ON_KLASS_REDEFINITION(the_class, current);)
4459
4460 _timer_rsc_phase1.stop();
4461 if (log_is_enabled(Info, redefine, class, timer)) {
4462 _timer_rsc_phase2.start();
4463 }
4464
4465 if (the_class->oop_map_cache() != nullptr) {
4466 // Flush references to any obsolete methods from the oop map cache
4467 // so that obsolete methods are not pinned.
4468 the_class->oop_map_cache()->flush_obsolete_entries();
4469 }
4470
4471 increment_class_counter(the_class);
4472
4473 if (EventClassRedefinition::is_enabled()) {
4474 EventClassRedefinition event;
4475 event.set_classModificationCount(java_lang_Class::classRedefinedCount(the_class->java_mirror()));
4476 event.set_redefinedClass(the_class);
4477 event.set_redefinitionId(_id);
4478 event.commit();
4479 }
4480
4481 {
4482 ResourceMark rm(current);
4483 // increment the classRedefinedCount field in the_class and in any
4484 // direct and indirect subclasses of the_class
4485 log_info(redefine, class, load)
4486 ("redefined name=%s, count=%d (avail_mem=" UINT64_FORMAT "K)",
4487 the_class->external_name(), java_lang_Class::classRedefinedCount(the_class->java_mirror()), os::available_memory() >> 10);
4488 Events::log_redefinition(current, "redefined class name=%s, count=%d",
4489 the_class->external_name(),
4490 java_lang_Class::classRedefinedCount(the_class->java_mirror()));
4491
4492 }
4493 _timer_rsc_phase2.stop();
4494
4495 } // end redefine_single_class()
4496
4497
4498 // Increment the classRedefinedCount field in the specific InstanceKlass
4499 // and in all direct and indirect subclasses.
4500 void VM_RedefineClasses::increment_class_counter(InstanceKlass* ik) {
4501 for (ClassHierarchyIterator iter(ik); !iter.done(); iter.next()) {
4502 // Only update instanceKlasses
4503 Klass* sub = iter.klass();
4504 if (sub->is_instance_klass()) {
4505 oop class_mirror = InstanceKlass::cast(sub)->java_mirror();
4506 Klass* class_oop = java_lang_Class::as_Klass(class_mirror);
4507 int new_count = java_lang_Class::classRedefinedCount(class_mirror) + 1;
4508 java_lang_Class::set_classRedefinedCount(class_mirror, new_count);
4509
4510 if (class_oop != _the_class) {
4511 // _the_class count is printed at end of redefine_single_class()
4512 log_debug(redefine, class, subclass)("updated count in subclass=%s to %d", ik->external_name(), new_count);
4513 }
4514 }
4515 }
4516 }
4517
4518 void VM_RedefineClasses::CheckClass::do_klass(Klass* k) {
4519 bool no_old_methods = true; // be optimistic
4520
4521 // Both array and instance classes have vtables.
4522 // a vtable should never contain old or obsolete methods
4523 ResourceMark rm(_thread);
4524 if (k->vtable_length() > 0 &&
4525 !k->vtable().check_no_old_or_obsolete_entries()) {
4526 if (log_is_enabled(Trace, redefine, class, obsolete, metadata)) {
4527 log_trace(redefine, class, obsolete, metadata)
4528 ("klassVtable::check_no_old_or_obsolete_entries failure -- OLD or OBSOLETE method found -- class: %s",
4529 k->signature_name());
4530 k->vtable().dump_vtable();
4531 }
4532 no_old_methods = false;
4533 }
4534
4535 if (k->is_instance_klass()) {
4536 HandleMark hm(_thread);
4537 InstanceKlass *ik = InstanceKlass::cast(k);
4538
4539 // an itable should never contain old or obsolete methods
4540 if (ik->itable_length() > 0 &&
4541 !ik->itable().check_no_old_or_obsolete_entries()) {
4542 if (log_is_enabled(Trace, redefine, class, obsolete, metadata)) {
4543 log_trace(redefine, class, obsolete, metadata)
4544 ("klassItable::check_no_old_or_obsolete_entries failure -- OLD or OBSOLETE method found -- class: %s",
4545 ik->signature_name());
4546 ik->itable().dump_itable();
4547 }
4548 no_old_methods = false;
4549 }
4550
4551 // the constant pool cache should never contain non-deleted old or obsolete methods
4552 if (ik->constants() != nullptr &&
4553 ik->constants()->cache() != nullptr &&
4554 !ik->constants()->cache()->check_no_old_or_obsolete_entries()) {
4555 if (log_is_enabled(Trace, redefine, class, obsolete, metadata)) {
4556 log_trace(redefine, class, obsolete, metadata)
4557 ("cp-cache::check_no_old_or_obsolete_entries failure -- OLD or OBSOLETE method found -- class: %s",
4558 ik->signature_name());
4559 ik->constants()->cache()->dump_cache();
4560 }
4561 no_old_methods = false;
4562 }
4563 }
4564
4565 // print and fail guarantee if old methods are found.
4566 if (!no_old_methods) {
4567 if (log_is_enabled(Trace, redefine, class, obsolete, metadata)) {
4568 dump_methods();
4569 } else {
4570 log_trace(redefine, class)("Use the '-Xlog:redefine+class*:' option "
4571 "to see more info about the following guarantee() failure.");
4572 }
4573 guarantee(false, "OLD and/or OBSOLETE method(s) found");
4574 }
4575 }
4576
4577 u8 VM_RedefineClasses::next_id() {
4578 while (true) {
4579 u8 id = _id_counter;
4580 u8 next_id = id + 1;
4581 u8 result = Atomic::cmpxchg(&_id_counter, id, next_id);
4582 if (result == id) {
4583 return next_id;
4584 }
4585 }
4586 }
4587
4588 void VM_RedefineClasses::dump_methods() {
4589 int j;
4590 log_trace(redefine, class, dump)("_old_methods --");
4591 for (j = 0; j < _old_methods->length(); ++j) {
4592 LogStreamHandle(Trace, redefine, class, dump) log_stream;
4593 Method* m = _old_methods->at(j);
4594 log_stream.print("%4d (%5d) ", j, m->vtable_index());
4595 m->access_flags().print_on(&log_stream);
4596 log_stream.print(" -- ");
4597 m->print_name(&log_stream);
4598 log_stream.cr();
4599 }
4600 log_trace(redefine, class, dump)("_new_methods --");
4601 for (j = 0; j < _new_methods->length(); ++j) {
4602 LogStreamHandle(Trace, redefine, class, dump) log_stream;
4603 Method* m = _new_methods->at(j);
4604 log_stream.print("%4d (%5d) ", j, m->vtable_index());
4605 m->access_flags().print_on(&log_stream);
4606 log_stream.print(" -- ");
4607 m->print_name(&log_stream);
4608 log_stream.cr();
4609 }
4610 log_trace(redefine, class, dump)("_matching_methods --");
4611 for (j = 0; j < _matching_methods_length; ++j) {
4612 LogStreamHandle(Trace, redefine, class, dump) log_stream;
4613 Method* m = _matching_old_methods[j];
4614 log_stream.print("%4d (%5d) ", j, m->vtable_index());
4615 m->access_flags().print_on(&log_stream);
4616 log_stream.print(" -- ");
4617 m->print_name();
4618 log_stream.cr();
4619
4620 m = _matching_new_methods[j];
4621 log_stream.print(" (%5d) ", m->vtable_index());
4622 m->access_flags().print_on(&log_stream);
4623 log_stream.cr();
4624 }
4625 log_trace(redefine, class, dump)("_deleted_methods --");
4626 for (j = 0; j < _deleted_methods_length; ++j) {
4627 LogStreamHandle(Trace, redefine, class, dump) log_stream;
4628 Method* m = _deleted_methods[j];
4629 log_stream.print("%4d (%5d) ", j, m->vtable_index());
4630 m->access_flags().print_on(&log_stream);
4631 log_stream.print(" -- ");
4632 m->print_name(&log_stream);
4633 log_stream.cr();
4634 }
4635 log_trace(redefine, class, dump)("_added_methods --");
4636 for (j = 0; j < _added_methods_length; ++j) {
4637 LogStreamHandle(Trace, redefine, class, dump) log_stream;
4638 Method* m = _added_methods[j];
4639 log_stream.print("%4d (%5d) ", j, m->vtable_index());
4640 m->access_flags().print_on(&log_stream);
4641 log_stream.print(" -- ");
4642 m->print_name(&log_stream);
4643 log_stream.cr();
4644 }
4645 }
4646
4647 void VM_RedefineClasses::print_on_error(outputStream* st) const {
4648 VM_Operation::print_on_error(st);
4649 if (_the_class != nullptr) {
4650 ResourceMark rm;
4651 st->print_cr(", redefining class %s", _the_class->external_name());
4652 }
4653 }