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