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