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 if (merge_cp_p == nullptr) {
1586 assert(false, "caller must provide scratch constantPool");
1587 return false; // robustness
1588 }
1589 if (merge_cp_length_p == nullptr) {
1590 assert(false, "caller must provide scratch CP length");
1591 return false; // robustness
1592 }
1593 // Worst case we need old_cp->length() + scratch_cp()->length(),
1594 // but the caller might be smart so make sure we have at least
1595 // the minimum.
1596 if ((*merge_cp_p)->length() < old_cp->length()) {
1597 assert(false, "merge area too small");
1598 return false; // robustness
1599 }
1600
1601 log_info(redefine, class, constantpool)("old_cp_len=%d, scratch_cp_len=%d", old_cp->length(), scratch_cp->length());
1602
1603 {
1604 // Pass 0:
1605 // The old_cp is copied to *merge_cp_p; this means that any code
1606 // using old_cp does not have to change. This work looks like a
1607 // perfect fit for ConstantPool*::copy_cp_to(), but we need to
1608 // handle one special case:
1609 // - revert JVM_CONSTANT_Class to JVM_CONSTANT_UnresolvedClass
1610 // This will make verification happy.
1611
1612 int old_i; // index into old_cp
1613
1614 // index zero (0) is not used in constantPools
1615 for (old_i = 1; old_i < old_cp->length(); old_i++) {
1616 // leave debugging crumb
1617 jbyte old_tag = old_cp->tag_at(old_i).value();
1618 switch (old_tag) {
1619 case JVM_CONSTANT_Class:
1620 case JVM_CONSTANT_UnresolvedClass:
1621 // revert the copy to JVM_CONSTANT_UnresolvedClass
1622 // May be resolving while calling this so do the same for
1623 // JVM_CONSTANT_UnresolvedClass (klass_name_at() deals with transition)
1624 (*merge_cp_p)->temp_unresolved_klass_at_put(old_i,
1625 old_cp->klass_name_index_at(old_i));
1626 break;
1627
1628 case JVM_CONSTANT_Double:
1629 case JVM_CONSTANT_Long:
1630 // just copy the entry to *merge_cp_p, but double and long take
1631 // two constant pool entries
1632 ConstantPool::copy_entry_to(old_cp, old_i, *merge_cp_p, old_i);
1633 old_i++;
1634 break;
1635
1636 default:
1637 // just copy the entry to *merge_cp_p
1638 ConstantPool::copy_entry_to(old_cp, old_i, *merge_cp_p, old_i);
1639 break;
1640 }
1641 } // end for each old_cp entry
1642
1643 ConstantPool::copy_operands(old_cp, *merge_cp_p, CHECK_false);
1644 (*merge_cp_p)->extend_operands(scratch_cp, CHECK_false);
1645
1646 // We don't need to sanity check that *merge_cp_length_p is within
1647 // *merge_cp_p bounds since we have the minimum on-entry check above.
1648 (*merge_cp_length_p) = old_i;
1649 }
1650
1651 // merge_cp_len should be the same as old_cp->length() at this point
1652 // so this trace message is really a "warm-and-breathing" message.
1653 log_debug(redefine, class, constantpool)("after pass 0: merge_cp_len=%d", *merge_cp_length_p);
1654
1655 int scratch_i; // index into scratch_cp
1656 {
1657 // Pass 1a:
1658 // Compare scratch_cp entries to the old_cp entries that we have
1659 // already copied to *merge_cp_p. In this pass, we are eliminating
1660 // exact duplicates (matching entry at same index) so we only
1661 // compare entries in the common indice range.
1662 int increment = 1;
1663 int pass1a_length = MIN2(old_cp->length(), scratch_cp->length());
1664 for (scratch_i = 1; scratch_i < pass1a_length; scratch_i += increment) {
1665 switch (scratch_cp->tag_at(scratch_i).value()) {
1666 case JVM_CONSTANT_Double:
1667 case JVM_CONSTANT_Long:
1668 // double and long take two constant pool entries
1669 increment = 2;
1670 break;
1671
1672 default:
1673 increment = 1;
1674 break;
1675 }
1676
1677 bool match = scratch_cp->compare_entry_to(scratch_i, *merge_cp_p, scratch_i);
1678 if (match) {
1679 // found a match at the same index so nothing more to do
1680 continue;
1681 }
1682
1683 int found_i = scratch_cp->find_matching_entry(scratch_i, *merge_cp_p);
1684 if (found_i != 0) {
1685 guarantee(found_i != scratch_i,
1686 "compare_entry_to() and find_matching_entry() do not agree");
1687
1688 // Found a matching entry somewhere else in *merge_cp_p so
1689 // just need a mapping entry.
1690 map_index(scratch_cp, scratch_i, found_i);
1691 continue;
1692 }
1693
1694 // No match found so we have to append this entry and any unique
1695 // referenced entries to *merge_cp_p.
1696 append_entry(scratch_cp, scratch_i, merge_cp_p, merge_cp_length_p);
1697 }
1698 }
1699
1700 log_debug(redefine, class, constantpool)
1701 ("after pass 1a: merge_cp_len=%d, scratch_i=%d, index_map_len=%d",
1702 *merge_cp_length_p, scratch_i, _index_map_count);
1703
1704 if (scratch_i < scratch_cp->length()) {
1705 // Pass 1b:
1706 // old_cp is smaller than scratch_cp so there are entries in
1707 // scratch_cp that we have not yet processed. We take care of
1708 // those now.
1709 int increment = 1;
1710 for (; scratch_i < scratch_cp->length(); scratch_i += increment) {
1711 switch (scratch_cp->tag_at(scratch_i).value()) {
1712 case JVM_CONSTANT_Double:
1713 case JVM_CONSTANT_Long:
1714 // double and long take two constant pool entries
1715 increment = 2;
1716 break;
1717
1718 default:
1719 increment = 1;
1720 break;
1721 }
1722
1723 int found_i =
1724 scratch_cp->find_matching_entry(scratch_i, *merge_cp_p);
1725 if (found_i != 0) {
1726 // Found a matching entry somewhere else in *merge_cp_p so
1727 // just need a mapping entry.
1728 map_index(scratch_cp, scratch_i, found_i);
1729 continue;
1730 }
1731
1732 // No match found so we have to append this entry and any unique
1733 // referenced entries to *merge_cp_p.
1734 append_entry(scratch_cp, scratch_i, merge_cp_p, merge_cp_length_p);
1735 }
1736
1737 log_debug(redefine, class, constantpool)
1738 ("after pass 1b: merge_cp_len=%d, scratch_i=%d, index_map_len=%d",
1739 *merge_cp_length_p, scratch_i, _index_map_count);
1740 }
1741 finalize_operands_merge(*merge_cp_p, CHECK_false);
1742
1743 return true;
1744 } // end merge_constant_pools()
1745
1746
1747 // Scoped object to clean up the constant pool(s) created for merging
1748 class MergeCPCleaner {
1749 ClassLoaderData* _loader_data;
1750 ConstantPool* _cp;
1751 ConstantPool* _scratch_cp;
1752 public:
1753 MergeCPCleaner(ClassLoaderData* loader_data, ConstantPool* merge_cp) :
1754 _loader_data(loader_data), _cp(merge_cp), _scratch_cp(nullptr) {}
1755 ~MergeCPCleaner() {
1756 _loader_data->add_to_deallocate_list(_cp);
1757 if (_scratch_cp != nullptr) {
1758 _loader_data->add_to_deallocate_list(_scratch_cp);
1759 }
1760 }
1761 void add_scratch_cp(ConstantPool* scratch_cp) { _scratch_cp = scratch_cp; }
1762 };
1763
1764 // Merge constant pools between the_class and scratch_class and
1765 // potentially rewrite bytecodes in scratch_class to use the merged
1766 // constant pool.
1767 jvmtiError VM_RedefineClasses::merge_cp_and_rewrite(
1768 InstanceKlass* the_class, InstanceKlass* scratch_class,
1769 TRAPS) {
1770 // worst case merged constant pool length is old and new combined
1771 int merge_cp_length = the_class->constants()->length()
1772 + scratch_class->constants()->length();
1773
1774 // Constant pools are not easily reused so we allocate a new one
1775 // each time.
1776 // merge_cp is created unsafe for concurrent GC processing. It
1777 // should be marked safe before discarding it. Even though
1778 // garbage, if it crosses a card boundary, it may be scanned
1779 // in order to find the start of the first complete object on the card.
1780 ClassLoaderData* loader_data = the_class->class_loader_data();
1781 ConstantPool* merge_cp_oop =
1782 ConstantPool::allocate(loader_data,
1783 merge_cp_length,
1784 CHECK_(JVMTI_ERROR_OUT_OF_MEMORY));
1785 MergeCPCleaner cp_cleaner(loader_data, merge_cp_oop);
1786
1787 HandleMark hm(THREAD); // make sure handles are cleared before
1788 // MergeCPCleaner clears out merge_cp_oop
1789 constantPoolHandle merge_cp(THREAD, merge_cp_oop);
1790
1791 // Get constants() from the old class because it could have been rewritten
1792 // while we were at a safepoint allocating a new constant pool.
1793 constantPoolHandle old_cp(THREAD, the_class->constants());
1794 constantPoolHandle scratch_cp(THREAD, scratch_class->constants());
1795
1796 // If the length changed, the class was redefined out from under us. Return
1797 // an error.
1798 if (merge_cp_length != the_class->constants()->length()
1799 + scratch_class->constants()->length()) {
1800 return JVMTI_ERROR_INTERNAL;
1801 }
1802
1803 // Update the version number of the constant pools (may keep scratch_cp)
1804 merge_cp->increment_and_save_version(old_cp->version());
1805 scratch_cp->increment_and_save_version(old_cp->version());
1806
1807 ResourceMark rm(THREAD);
1808 _index_map_count = 0;
1809 _index_map_p = new intArray(scratch_cp->length(), scratch_cp->length(), -1);
1810
1811 _operands_cur_length = ConstantPool::operand_array_length(old_cp->operands());
1812 _operands_index_map_count = 0;
1813 int operands_index_map_len = ConstantPool::operand_array_length(scratch_cp->operands());
1814 _operands_index_map_p = new intArray(operands_index_map_len, operands_index_map_len, -1);
1815
1816 // reference to the cp holder is needed for copy_operands()
1817 merge_cp->set_pool_holder(scratch_class);
1818 bool result = merge_constant_pools(old_cp, scratch_cp, &merge_cp,
1819 &merge_cp_length, THREAD);
1820 merge_cp->set_pool_holder(nullptr);
1821
1822 if (!result) {
1823 // The merge can fail due to memory allocation failure or due
1824 // to robustness checks.
1825 return JVMTI_ERROR_INTERNAL;
1826 }
1827
1828 // ensure merged constant pool size does not overflow u2
1829 if (merge_cp_length > 0xFFFF) {
1830 log_warning(redefine, class, constantpool)("Merged constant pool overflow: %d entries", merge_cp_length);
1831 return JVMTI_ERROR_INTERNAL;
1832 }
1833
1834 // Set dynamic constants attribute from the original CP.
1835 if (old_cp->has_dynamic_constant()) {
1836 scratch_cp->set_has_dynamic_constant();
1837 }
1838
1839 log_info(redefine, class, constantpool)("merge_cp_len=%d, index_map_len=%d", merge_cp_length, _index_map_count);
1840
1841 if (_index_map_count == 0) {
1842 // there is nothing to map between the new and merged constant pools
1843
1844 // Copy attributes from scratch_cp to merge_cp
1845 merge_cp->copy_fields(scratch_cp());
1846
1847 if (old_cp->length() == scratch_cp->length()) {
1848 // The old and new constant pools are the same length and the
1849 // index map is empty. This means that the three constant pools
1850 // are equivalent (but not the same). Unfortunately, the new
1851 // constant pool has not gone through link resolution nor have
1852 // the new class bytecodes gone through constant pool cache
1853 // rewriting so we can't use the old constant pool with the new
1854 // class.
1855
1856 // toss the merged constant pool at return
1857 } else if (old_cp->length() < scratch_cp->length()) {
1858 // The old constant pool has fewer entries than the new constant
1859 // pool and the index map is empty. This means the new constant
1860 // pool is a superset of the old constant pool. However, the old
1861 // class bytecodes have already gone through constant pool cache
1862 // rewriting so we can't use the new constant pool with the old
1863 // class.
1864
1865 // toss the merged constant pool at return
1866 } else {
1867 // The old constant pool has more entries than the new constant
1868 // pool and the index map is empty. This means that both the old
1869 // and merged constant pools are supersets of the new constant
1870 // pool.
1871
1872 // Replace the new constant pool with a shrunken copy of the
1873 // merged constant pool
1874 set_new_constant_pool(loader_data, scratch_class, merge_cp, merge_cp_length,
1875 CHECK_(JVMTI_ERROR_OUT_OF_MEMORY));
1876 // The new constant pool replaces scratch_cp so have cleaner clean it up.
1877 // It can't be cleaned up while there are handles to it.
1878 cp_cleaner.add_scratch_cp(scratch_cp());
1879 }
1880 } else {
1881 if (log_is_enabled(Trace, redefine, class, constantpool)) {
1882 // don't want to loop unless we are tracing
1883 int count = 0;
1884 for (int i = 1; i < _index_map_p->length(); i++) {
1885 int value = _index_map_p->at(i);
1886
1887 if (value != -1) {
1888 log_trace(redefine, class, constantpool)("index_map[%d]: old=%d new=%d", count, i, value);
1889 count++;
1890 }
1891 }
1892 }
1893
1894 // We have entries mapped between the new and merged constant pools
1895 // so we have to rewrite some constant pool references.
1896 if (!rewrite_cp_refs(scratch_class)) {
1897 return JVMTI_ERROR_INTERNAL;
1898 }
1899
1900 // Copy attributes from scratch_cp to merge_cp (should be done after rewrite_cp_refs())
1901 merge_cp->copy_fields(scratch_cp());
1902
1903 // Replace the new constant pool with a shrunken copy of the
1904 // merged constant pool so now the rewritten bytecodes have
1905 // valid references; the previous new constant pool will get
1906 // GCed.
1907 set_new_constant_pool(loader_data, scratch_class, merge_cp, merge_cp_length,
1908 CHECK_(JVMTI_ERROR_OUT_OF_MEMORY));
1909 // The new constant pool replaces scratch_cp so have cleaner clean it up.
1910 // It can't be cleaned up while there are handles to it.
1911 cp_cleaner.add_scratch_cp(scratch_cp());
1912 }
1913
1914 return JVMTI_ERROR_NONE;
1915 } // end merge_cp_and_rewrite()
1916
1917
1918 // Rewrite constant pool references in klass scratch_class.
1919 bool VM_RedefineClasses::rewrite_cp_refs(InstanceKlass* scratch_class) {
1920
1921 // rewrite constant pool references in the nest attributes:
1922 if (!rewrite_cp_refs_in_nest_attributes(scratch_class)) {
1923 // propagate failure back to caller
1924 return false;
1925 }
1926
1927 // rewrite constant pool references in the Record attribute:
1928 if (!rewrite_cp_refs_in_record_attribute(scratch_class)) {
1929 // propagate failure back to caller
1930 return false;
1931 }
1932
1933 // rewrite constant pool references in the PermittedSubclasses attribute:
1934 if (!rewrite_cp_refs_in_permitted_subclasses_attribute(scratch_class)) {
1935 // propagate failure back to caller
1936 return false;
1937 }
1938
1939 // rewrite constant pool references in the methods:
1940 if (!rewrite_cp_refs_in_methods(scratch_class)) {
1941 // propagate failure back to caller
1942 return false;
1943 }
1944
1945 // rewrite constant pool references in the class_annotations:
1946 if (!rewrite_cp_refs_in_class_annotations(scratch_class)) {
1947 // propagate failure back to caller
1948 return false;
1949 }
1950
1951 // rewrite constant pool references in the fields_annotations:
1952 if (!rewrite_cp_refs_in_fields_annotations(scratch_class)) {
1953 // propagate failure back to caller
1954 return false;
1955 }
1956
1957 // rewrite constant pool references in the methods_annotations:
1958 if (!rewrite_cp_refs_in_methods_annotations(scratch_class)) {
1959 // propagate failure back to caller
1960 return false;
1961 }
1962
1963 // rewrite constant pool references in the methods_parameter_annotations:
1964 if (!rewrite_cp_refs_in_methods_parameter_annotations(scratch_class)) {
1965 // propagate failure back to caller
1966 return false;
1967 }
1968
1969 // rewrite constant pool references in the methods_default_annotations:
1970 if (!rewrite_cp_refs_in_methods_default_annotations(scratch_class)) {
1971 // propagate failure back to caller
1972 return false;
1973 }
1974
1975 // rewrite constant pool references in the class_type_annotations:
1976 if (!rewrite_cp_refs_in_class_type_annotations(scratch_class)) {
1977 // propagate failure back to caller
1978 return false;
1979 }
1980
1981 // rewrite constant pool references in the fields_type_annotations:
1982 if (!rewrite_cp_refs_in_fields_type_annotations(scratch_class)) {
1983 // propagate failure back to caller
1984 return false;
1985 }
1986
1987 // rewrite constant pool references in the methods_type_annotations:
1988 if (!rewrite_cp_refs_in_methods_type_annotations(scratch_class)) {
1989 // propagate failure back to caller
1990 return false;
1991 }
1992
1993 // There can be type annotations in the Code part of a method_info attribute.
1994 // These annotations are not accessible, even by reflection.
1995 // Currently they are not even parsed by the ClassFileParser.
1996 // If runtime access is added they will also need to be rewritten.
1997
1998 // rewrite source file name index:
1999 u2 source_file_name_idx = scratch_class->source_file_name_index();
2000 if (source_file_name_idx != 0) {
2001 u2 new_source_file_name_idx = find_new_index(source_file_name_idx);
2002 if (new_source_file_name_idx != 0) {
2003 scratch_class->set_source_file_name_index(new_source_file_name_idx);
2004 }
2005 }
2006
2007 // rewrite class generic signature index:
2008 u2 generic_signature_index = scratch_class->generic_signature_index();
2009 if (generic_signature_index != 0) {
2010 u2 new_generic_signature_index = find_new_index(generic_signature_index);
2011 if (new_generic_signature_index != 0) {
2012 scratch_class->set_generic_signature_index(new_generic_signature_index);
2013 }
2014 }
2015
2016 return true;
2017 } // end rewrite_cp_refs()
2018
2019 // Rewrite constant pool references in the NestHost and NestMembers attributes.
2020 bool VM_RedefineClasses::rewrite_cp_refs_in_nest_attributes(
2021 InstanceKlass* scratch_class) {
2022
2023 u2 cp_index = scratch_class->nest_host_index();
2024 if (cp_index != 0) {
2025 scratch_class->set_nest_host_index(find_new_index(cp_index));
2026 }
2027 Array<u2>* nest_members = scratch_class->nest_members();
2028 for (int i = 0; i < nest_members->length(); i++) {
2029 u2 cp_index = nest_members->at(i);
2030 nest_members->at_put(i, find_new_index(cp_index));
2031 }
2032 return true;
2033 }
2034
2035 // Rewrite constant pool references in the Record attribute.
2036 bool VM_RedefineClasses::rewrite_cp_refs_in_record_attribute(InstanceKlass* scratch_class) {
2037 Array<RecordComponent*>* components = scratch_class->record_components();
2038 if (components != nullptr) {
2039 for (int i = 0; i < components->length(); i++) {
2040 RecordComponent* component = components->at(i);
2041 u2 cp_index = component->name_index();
2042 component->set_name_index(find_new_index(cp_index));
2043 cp_index = component->descriptor_index();
2044 component->set_descriptor_index(find_new_index(cp_index));
2045 cp_index = component->generic_signature_index();
2046 if (cp_index != 0) {
2047 component->set_generic_signature_index(find_new_index(cp_index));
2048 }
2049
2050 AnnotationArray* annotations = component->annotations();
2051 if (annotations != nullptr && annotations->length() != 0) {
2052 int byte_i = 0; // byte index into annotations
2053 if (!rewrite_cp_refs_in_annotations_typeArray(annotations, byte_i)) {
2054 log_debug(redefine, class, annotation)("bad record_component_annotations at %d", i);
2055 // propagate failure back to caller
2056 return false;
2057 }
2058 }
2059
2060 AnnotationArray* type_annotations = component->type_annotations();
2061 if (type_annotations != nullptr && type_annotations->length() != 0) {
2062 int byte_i = 0; // byte index into annotations
2063 if (!rewrite_cp_refs_in_annotations_typeArray(type_annotations, byte_i)) {
2064 log_debug(redefine, class, annotation)("bad record_component_type_annotations at %d", i);
2065 // propagate failure back to caller
2066 return false;
2067 }
2068 }
2069 }
2070 }
2071 return true;
2072 }
2073
2074 // Rewrite constant pool references in the PermittedSubclasses attribute.
2075 bool VM_RedefineClasses::rewrite_cp_refs_in_permitted_subclasses_attribute(
2076 InstanceKlass* scratch_class) {
2077
2078 Array<u2>* permitted_subclasses = scratch_class->permitted_subclasses();
2079 assert(permitted_subclasses != nullptr, "unexpected null permitted_subclasses");
2080 for (int i = 0; i < permitted_subclasses->length(); i++) {
2081 u2 cp_index = permitted_subclasses->at(i);
2082 permitted_subclasses->at_put(i, find_new_index(cp_index));
2083 }
2084 return true;
2085 }
2086
2087 // Rewrite constant pool references in the methods.
2088 bool VM_RedefineClasses::rewrite_cp_refs_in_methods(InstanceKlass* scratch_class) {
2089
2090 Array<Method*>* methods = scratch_class->methods();
2091
2092 if (methods == nullptr || methods->length() == 0) {
2093 // no methods so nothing to do
2094 return true;
2095 }
2096
2097 JavaThread* THREAD = JavaThread::current(); // For exception macros.
2098 ExceptionMark em(THREAD);
2099
2100 // rewrite constant pool references in the methods:
2101 for (int i = methods->length() - 1; i >= 0; i--) {
2102 methodHandle method(THREAD, methods->at(i));
2103 methodHandle new_method;
2104 rewrite_cp_refs_in_method(method, &new_method, THREAD);
2105 if (!new_method.is_null()) {
2106 // the method has been replaced so save the new method version
2107 // even in the case of an exception. original method is on the
2108 // deallocation list.
2109 methods->at_put(i, new_method());
2110 }
2111 if (HAS_PENDING_EXCEPTION) {
2112 Symbol* ex_name = PENDING_EXCEPTION->klass()->name();
2113 log_info(redefine, class, load, exceptions)("rewrite_cp_refs_in_method exception: '%s'", ex_name->as_C_string());
2114 // Need to clear pending exception here as the super caller sets
2115 // the JVMTI_ERROR_INTERNAL if the returned value is false.
2116 CLEAR_PENDING_EXCEPTION;
2117 return false;
2118 }
2119 }
2120
2121 return true;
2122 }
2123
2124
2125 // Rewrite constant pool references in the specific method. This code
2126 // was adapted from Rewriter::rewrite_method().
2127 void VM_RedefineClasses::rewrite_cp_refs_in_method(methodHandle method,
2128 methodHandle *new_method_p, TRAPS) {
2129
2130 *new_method_p = methodHandle(); // default is no new method
2131
2132 // We cache a pointer to the bytecodes here in code_base. If GC
2133 // moves the Method*, then the bytecodes will also move which
2134 // will likely cause a crash. We create a NoSafepointVerifier
2135 // object to detect whether we pass a possible safepoint in this
2136 // code block.
2137 NoSafepointVerifier nsv;
2138
2139 // Bytecodes and their length
2140 address code_base = method->code_base();
2141 int code_length = method->code_size();
2142
2143 int bc_length;
2144 for (int bci = 0; bci < code_length; bci += bc_length) {
2145 address bcp = code_base + bci;
2146 Bytecodes::Code c = (Bytecodes::Code)(*bcp);
2147
2148 bc_length = Bytecodes::length_for(c);
2149 if (bc_length == 0) {
2150 // More complicated bytecodes report a length of zero so
2151 // we have to try again a slightly different way.
2152 bc_length = Bytecodes::length_at(method(), bcp);
2153 }
2154
2155 assert(bc_length != 0, "impossible bytecode length");
2156
2157 switch (c) {
2158 case Bytecodes::_ldc:
2159 {
2160 u1 cp_index = *(bcp + 1);
2161 u2 new_index = find_new_index(cp_index);
2162
2163 if (StressLdcRewrite && new_index == 0) {
2164 // If we are stressing ldc -> ldc_w rewriting, then we
2165 // always need a new_index value.
2166 new_index = cp_index;
2167 }
2168 if (new_index != 0) {
2169 // the original index is mapped so we have more work to do
2170 if (!StressLdcRewrite && new_index <= max_jubyte) {
2171 // The new value can still use ldc instead of ldc_w
2172 // unless we are trying to stress ldc -> ldc_w rewriting
2173 log_trace(redefine, class, constantpool)
2174 ("%s@" INTPTR_FORMAT " old=%d, new=%d", Bytecodes::name(c), p2i(bcp), cp_index, new_index);
2175 // We checked that new_index fits in a u1 so this cast is safe
2176 *(bcp + 1) = (u1)new_index;
2177 } else {
2178 log_trace(redefine, class, constantpool)
2179 ("%s->ldc_w@" INTPTR_FORMAT " old=%d, new=%d", Bytecodes::name(c), p2i(bcp), cp_index, new_index);
2180 // the new value needs ldc_w instead of ldc
2181 u_char inst_buffer[4]; // max instruction size is 4 bytes
2182 bcp = (address)inst_buffer;
2183 // construct new instruction sequence
2184 *bcp = Bytecodes::_ldc_w;
2185 bcp++;
2186 // Rewriter::rewrite_method() does not rewrite ldc -> ldc_w.
2187 // See comment below for difference between put_Java_u2()
2188 // and put_native_u2().
2189 Bytes::put_Java_u2(bcp, new_index);
2190
2191 Relocator rc(method, nullptr /* no RelocatorListener needed */);
2192 methodHandle m;
2193 {
2194 PauseNoSafepointVerifier pnsv(&nsv);
2195
2196 // ldc is 2 bytes and ldc_w is 3 bytes
2197 m = rc.insert_space_at(bci, 3, inst_buffer, CHECK);
2198 }
2199
2200 // return the new method so that the caller can update
2201 // the containing class
2202 *new_method_p = method = m;
2203 // switch our bytecode processing loop from the old method
2204 // to the new method
2205 code_base = method->code_base();
2206 code_length = method->code_size();
2207 bcp = code_base + bci;
2208 c = (Bytecodes::Code)(*bcp);
2209 bc_length = Bytecodes::length_for(c);
2210 assert(bc_length != 0, "sanity check");
2211 } // end we need ldc_w instead of ldc
2212 } // end if there is a mapped index
2213 } break;
2214
2215 // these bytecodes have a two-byte constant pool index
2216 case Bytecodes::_anewarray : // fall through
2217 case Bytecodes::_checkcast : // fall through
2218 case Bytecodes::_getfield : // fall through
2219 case Bytecodes::_getstatic : // fall through
2220 case Bytecodes::_instanceof : // fall through
2221 case Bytecodes::_invokedynamic : // fall through
2222 case Bytecodes::_invokeinterface: // fall through
2223 case Bytecodes::_invokespecial : // fall through
2224 case Bytecodes::_invokestatic : // fall through
2225 case Bytecodes::_invokevirtual : // fall through
2226 case Bytecodes::_ldc_w : // fall through
2227 case Bytecodes::_ldc2_w : // fall through
2228 case Bytecodes::_multianewarray : // fall through
2229 case Bytecodes::_new : // fall through
2230 case Bytecodes::_putfield : // fall through
2231 case Bytecodes::_putstatic :
2232 {
2233 address p = bcp + 1;
2234 int cp_index = Bytes::get_Java_u2(p);
2235 u2 new_index = find_new_index(cp_index);
2236 if (new_index != 0) {
2237 // the original index is mapped so update w/ new value
2238 log_trace(redefine, class, constantpool)
2239 ("%s@" INTPTR_FORMAT " old=%d, new=%d", Bytecodes::name(c),p2i(bcp), cp_index, new_index);
2240 // Rewriter::rewrite_method() uses put_native_u2() in this
2241 // situation because it is reusing the constant pool index
2242 // location for a native index into the ConstantPoolCache.
2243 // Since we are updating the constant pool index prior to
2244 // verification and ConstantPoolCache initialization, we
2245 // need to keep the new index in Java byte order.
2246 Bytes::put_Java_u2(p, new_index);
2247 }
2248 } break;
2249 default:
2250 break;
2251 }
2252 } // end for each bytecode
2253 } // end rewrite_cp_refs_in_method()
2254
2255
2256 // Rewrite constant pool references in the class_annotations field.
2257 bool VM_RedefineClasses::rewrite_cp_refs_in_class_annotations(InstanceKlass* scratch_class) {
2258
2259 AnnotationArray* class_annotations = scratch_class->class_annotations();
2260 if (class_annotations == nullptr || class_annotations->length() == 0) {
2261 // no class_annotations so nothing to do
2262 return true;
2263 }
2264
2265 log_debug(redefine, class, annotation)("class_annotations length=%d", class_annotations->length());
2266
2267 int byte_i = 0; // byte index into class_annotations
2268 return rewrite_cp_refs_in_annotations_typeArray(class_annotations, byte_i);
2269 }
2270
2271
2272 // Rewrite constant pool references in an annotations typeArray. This
2273 // "structure" is adapted from the RuntimeVisibleAnnotations_attribute
2274 // that is described in section 4.8.15 of the 2nd-edition of the VM spec:
2275 //
2276 // annotations_typeArray {
2277 // u2 num_annotations;
2278 // annotation annotations[num_annotations];
2279 // }
2280 //
2281 bool VM_RedefineClasses::rewrite_cp_refs_in_annotations_typeArray(
2282 AnnotationArray* annotations_typeArray, int &byte_i_ref) {
2283
2284 if ((byte_i_ref + 2) > annotations_typeArray->length()) {
2285 // not enough room for num_annotations field
2286 log_debug(redefine, class, annotation)("length() is too small for num_annotations field");
2287 return false;
2288 }
2289
2290 u2 num_annotations = Bytes::get_Java_u2((address)
2291 annotations_typeArray->adr_at(byte_i_ref));
2292 byte_i_ref += 2;
2293
2294 log_debug(redefine, class, annotation)("num_annotations=%d", num_annotations);
2295
2296 int calc_num_annotations = 0;
2297 for (; calc_num_annotations < num_annotations; calc_num_annotations++) {
2298 if (!rewrite_cp_refs_in_annotation_struct(annotations_typeArray, byte_i_ref)) {
2299 log_debug(redefine, class, annotation)("bad annotation_struct at %d", calc_num_annotations);
2300 // propagate failure back to caller
2301 return false;
2302 }
2303 }
2304 assert(num_annotations == calc_num_annotations, "sanity check");
2305
2306 return true;
2307 } // end rewrite_cp_refs_in_annotations_typeArray()
2308
2309
2310 // Rewrite constant pool references in the annotation struct portion of
2311 // an annotations_typeArray. This "structure" is from section 4.8.15 of
2312 // the 2nd-edition of the VM spec:
2313 //
2314 // struct annotation {
2315 // u2 type_index;
2316 // u2 num_element_value_pairs;
2317 // {
2318 // u2 element_name_index;
2319 // element_value value;
2320 // } element_value_pairs[num_element_value_pairs];
2321 // }
2322 //
2323 bool VM_RedefineClasses::rewrite_cp_refs_in_annotation_struct(
2324 AnnotationArray* annotations_typeArray, int &byte_i_ref) {
2325 if ((byte_i_ref + 2 + 2) > annotations_typeArray->length()) {
2326 // not enough room for smallest annotation_struct
2327 log_debug(redefine, class, annotation)("length() is too small for annotation_struct");
2328 return false;
2329 }
2330
2331 u2 type_index = rewrite_cp_ref_in_annotation_data(annotations_typeArray,
2332 byte_i_ref, "type_index");
2333
2334 u2 num_element_value_pairs = Bytes::get_Java_u2((address)
2335 annotations_typeArray->adr_at(byte_i_ref));
2336 byte_i_ref += 2;
2337
2338 log_debug(redefine, class, annotation)
2339 ("type_index=%d num_element_value_pairs=%d", type_index, num_element_value_pairs);
2340
2341 int calc_num_element_value_pairs = 0;
2342 for (; calc_num_element_value_pairs < num_element_value_pairs;
2343 calc_num_element_value_pairs++) {
2344 if ((byte_i_ref + 2) > annotations_typeArray->length()) {
2345 // not enough room for another element_name_index, let alone
2346 // the rest of another component
2347 log_debug(redefine, class, annotation)("length() is too small for element_name_index");
2348 return false;
2349 }
2350
2351 u2 element_name_index = rewrite_cp_ref_in_annotation_data(
2352 annotations_typeArray, byte_i_ref,
2353 "element_name_index");
2354
2355 log_debug(redefine, class, annotation)("element_name_index=%d", element_name_index);
2356
2357 if (!rewrite_cp_refs_in_element_value(annotations_typeArray, byte_i_ref)) {
2358 log_debug(redefine, class, annotation)("bad element_value at %d", calc_num_element_value_pairs);
2359 // propagate failure back to caller
2360 return false;
2361 }
2362 } // end for each component
2363 assert(num_element_value_pairs == calc_num_element_value_pairs,
2364 "sanity check");
2365
2366 return true;
2367 } // end rewrite_cp_refs_in_annotation_struct()
2368
2369
2370 // Rewrite a constant pool reference at the current position in
2371 // annotations_typeArray if needed. Returns the original constant
2372 // pool reference if a rewrite was not needed or the new constant
2373 // pool reference if a rewrite was needed.
2374 u2 VM_RedefineClasses::rewrite_cp_ref_in_annotation_data(
2375 AnnotationArray* annotations_typeArray, int &byte_i_ref,
2376 const char * trace_mesg) {
2377
2378 address cp_index_addr = (address)
2379 annotations_typeArray->adr_at(byte_i_ref);
2380 u2 old_cp_index = Bytes::get_Java_u2(cp_index_addr);
2381 u2 new_cp_index = find_new_index(old_cp_index);
2382 if (new_cp_index != 0) {
2383 log_debug(redefine, class, annotation)("mapped old %s=%d", trace_mesg, old_cp_index);
2384 Bytes::put_Java_u2(cp_index_addr, new_cp_index);
2385 old_cp_index = new_cp_index;
2386 }
2387 byte_i_ref += 2;
2388 return old_cp_index;
2389 }
2390
2391
2392 // Rewrite constant pool references in the element_value portion of an
2393 // annotations_typeArray. This "structure" is from section 4.8.15.1 of
2394 // the 2nd-edition of the VM spec:
2395 //
2396 // struct element_value {
2397 // u1 tag;
2398 // union {
2399 // u2 const_value_index;
2400 // {
2401 // u2 type_name_index;
2402 // u2 const_name_index;
2403 // } enum_const_value;
2404 // u2 class_info_index;
2405 // annotation annotation_value;
2406 // struct {
2407 // u2 num_values;
2408 // element_value values[num_values];
2409 // } array_value;
2410 // } value;
2411 // }
2412 //
2413 bool VM_RedefineClasses::rewrite_cp_refs_in_element_value(
2414 AnnotationArray* annotations_typeArray, int &byte_i_ref) {
2415
2416 if ((byte_i_ref + 1) > annotations_typeArray->length()) {
2417 // not enough room for a tag let alone the rest of an element_value
2418 log_debug(redefine, class, annotation)("length() is too small for a tag");
2419 return false;
2420 }
2421
2422 u1 tag = annotations_typeArray->at(byte_i_ref);
2423 byte_i_ref++;
2424 log_debug(redefine, class, annotation)("tag='%c'", tag);
2425
2426 switch (tag) {
2427 // These BaseType tag values are from Table 4.2 in VM spec:
2428 case JVM_SIGNATURE_BYTE:
2429 case JVM_SIGNATURE_CHAR:
2430 case JVM_SIGNATURE_DOUBLE:
2431 case JVM_SIGNATURE_FLOAT:
2432 case JVM_SIGNATURE_INT:
2433 case JVM_SIGNATURE_LONG:
2434 case JVM_SIGNATURE_SHORT:
2435 case JVM_SIGNATURE_BOOLEAN:
2436
2437 // The remaining tag values are from Table 4.8 in the 2nd-edition of
2438 // the VM spec:
2439 case 's':
2440 {
2441 // For the above tag values (including the BaseType values),
2442 // value.const_value_index is right union field.
2443
2444 if ((byte_i_ref + 2) > annotations_typeArray->length()) {
2445 // not enough room for a const_value_index
2446 log_debug(redefine, class, annotation)("length() is too small for a const_value_index");
2447 return false;
2448 }
2449
2450 u2 const_value_index = rewrite_cp_ref_in_annotation_data(
2451 annotations_typeArray, byte_i_ref,
2452 "const_value_index");
2453
2454 log_debug(redefine, class, annotation)("const_value_index=%d", const_value_index);
2455 } break;
2456
2457 case 'e':
2458 {
2459 // for the above tag value, value.enum_const_value is right union field
2460
2461 if ((byte_i_ref + 4) > annotations_typeArray->length()) {
2462 // not enough room for a enum_const_value
2463 log_debug(redefine, class, annotation)("length() is too small for a enum_const_value");
2464 return false;
2465 }
2466
2467 u2 type_name_index = rewrite_cp_ref_in_annotation_data(
2468 annotations_typeArray, byte_i_ref,
2469 "type_name_index");
2470
2471 u2 const_name_index = rewrite_cp_ref_in_annotation_data(
2472 annotations_typeArray, byte_i_ref,
2473 "const_name_index");
2474
2475 log_debug(redefine, class, annotation)
2476 ("type_name_index=%d const_name_index=%d", type_name_index, const_name_index);
2477 } break;
2478
2479 case 'c':
2480 {
2481 // for the above tag value, value.class_info_index is right union field
2482
2483 if ((byte_i_ref + 2) > annotations_typeArray->length()) {
2484 // not enough room for a class_info_index
2485 log_debug(redefine, class, annotation)("length() is too small for a class_info_index");
2486 return false;
2487 }
2488
2489 u2 class_info_index = rewrite_cp_ref_in_annotation_data(
2490 annotations_typeArray, byte_i_ref,
2491 "class_info_index");
2492
2493 log_debug(redefine, class, annotation)("class_info_index=%d", class_info_index);
2494 } break;
2495
2496 case '@':
2497 // For the above tag value, value.attr_value is the right union
2498 // field. This is a nested annotation.
2499 if (!rewrite_cp_refs_in_annotation_struct(annotations_typeArray, byte_i_ref)) {
2500 // propagate failure back to caller
2501 return false;
2502 }
2503 break;
2504
2505 case JVM_SIGNATURE_ARRAY:
2506 {
2507 if ((byte_i_ref + 2) > annotations_typeArray->length()) {
2508 // not enough room for a num_values field
2509 log_debug(redefine, class, annotation)("length() is too small for a num_values field");
2510 return false;
2511 }
2512
2513 // For the above tag value, value.array_value is the right union
2514 // field. This is an array of nested element_value.
2515 u2 num_values = Bytes::get_Java_u2((address)
2516 annotations_typeArray->adr_at(byte_i_ref));
2517 byte_i_ref += 2;
2518 log_debug(redefine, class, annotation)("num_values=%d", num_values);
2519
2520 int calc_num_values = 0;
2521 for (; calc_num_values < num_values; calc_num_values++) {
2522 if (!rewrite_cp_refs_in_element_value(annotations_typeArray, byte_i_ref)) {
2523 log_debug(redefine, class, annotation)("bad nested element_value at %d", calc_num_values);
2524 // propagate failure back to caller
2525 return false;
2526 }
2527 }
2528 assert(num_values == calc_num_values, "sanity check");
2529 } break;
2530
2531 default:
2532 log_debug(redefine, class, annotation)("bad tag=0x%x", tag);
2533 return false;
2534 } // end decode tag field
2535
2536 return true;
2537 } // end rewrite_cp_refs_in_element_value()
2538
2539
2540 // Rewrite constant pool references in a fields_annotations field.
2541 bool VM_RedefineClasses::rewrite_cp_refs_in_fields_annotations(
2542 InstanceKlass* scratch_class) {
2543
2544 Array<AnnotationArray*>* fields_annotations = scratch_class->fields_annotations();
2545
2546 if (fields_annotations == nullptr || fields_annotations->length() == 0) {
2547 // no fields_annotations so nothing to do
2548 return true;
2549 }
2550
2551 log_debug(redefine, class, annotation)("fields_annotations length=%d", fields_annotations->length());
2552
2553 for (int i = 0; i < fields_annotations->length(); i++) {
2554 AnnotationArray* field_annotations = fields_annotations->at(i);
2555 if (field_annotations == nullptr || field_annotations->length() == 0) {
2556 // this field does not have any annotations so skip it
2557 continue;
2558 }
2559
2560 int byte_i = 0; // byte index into field_annotations
2561 if (!rewrite_cp_refs_in_annotations_typeArray(field_annotations, byte_i)) {
2562 log_debug(redefine, class, annotation)("bad field_annotations at %d", i);
2563 // propagate failure back to caller
2564 return false;
2565 }
2566 }
2567
2568 return true;
2569 } // end rewrite_cp_refs_in_fields_annotations()
2570
2571
2572 // Rewrite constant pool references in a methods_annotations field.
2573 bool VM_RedefineClasses::rewrite_cp_refs_in_methods_annotations(
2574 InstanceKlass* scratch_class) {
2575
2576 for (int i = 0; i < scratch_class->methods()->length(); i++) {
2577 Method* m = scratch_class->methods()->at(i);
2578 AnnotationArray* method_annotations = m->constMethod()->method_annotations();
2579
2580 if (method_annotations == nullptr || method_annotations->length() == 0) {
2581 // this method does not have any annotations so skip it
2582 continue;
2583 }
2584
2585 int byte_i = 0; // byte index into method_annotations
2586 if (!rewrite_cp_refs_in_annotations_typeArray(method_annotations, byte_i)) {
2587 log_debug(redefine, class, annotation)("bad method_annotations at %d", i);
2588 // propagate failure back to caller
2589 return false;
2590 }
2591 }
2592
2593 return true;
2594 } // end rewrite_cp_refs_in_methods_annotations()
2595
2596
2597 // Rewrite constant pool references in a methods_parameter_annotations
2598 // field. This "structure" is adapted from the
2599 // RuntimeVisibleParameterAnnotations_attribute described in section
2600 // 4.8.17 of the 2nd-edition of the VM spec:
2601 //
2602 // methods_parameter_annotations_typeArray {
2603 // u1 num_parameters;
2604 // {
2605 // u2 num_annotations;
2606 // annotation annotations[num_annotations];
2607 // } parameter_annotations[num_parameters];
2608 // }
2609 //
2610 bool VM_RedefineClasses::rewrite_cp_refs_in_methods_parameter_annotations(
2611 InstanceKlass* scratch_class) {
2612
2613 for (int i = 0; i < scratch_class->methods()->length(); i++) {
2614 Method* m = scratch_class->methods()->at(i);
2615 AnnotationArray* method_parameter_annotations = m->constMethod()->parameter_annotations();
2616 if (method_parameter_annotations == nullptr
2617 || method_parameter_annotations->length() == 0) {
2618 // this method does not have any parameter annotations so skip it
2619 continue;
2620 }
2621
2622 if (method_parameter_annotations->length() < 1) {
2623 // not enough room for a num_parameters field
2624 log_debug(redefine, class, annotation)("length() is too small for a num_parameters field at %d", i);
2625 return false;
2626 }
2627
2628 int byte_i = 0; // byte index into method_parameter_annotations
2629
2630 u1 num_parameters = method_parameter_annotations->at(byte_i);
2631 byte_i++;
2632
2633 log_debug(redefine, class, annotation)("num_parameters=%d", num_parameters);
2634
2635 int calc_num_parameters = 0;
2636 for (; calc_num_parameters < num_parameters; calc_num_parameters++) {
2637 if (!rewrite_cp_refs_in_annotations_typeArray(method_parameter_annotations, byte_i)) {
2638 log_debug(redefine, class, annotation)("bad method_parameter_annotations at %d", calc_num_parameters);
2639 // propagate failure back to caller
2640 return false;
2641 }
2642 }
2643 assert(num_parameters == calc_num_parameters, "sanity check");
2644 }
2645
2646 return true;
2647 } // end rewrite_cp_refs_in_methods_parameter_annotations()
2648
2649
2650 // Rewrite constant pool references in a methods_default_annotations
2651 // field. This "structure" is adapted from the AnnotationDefault_attribute
2652 // that is described in section 4.8.19 of the 2nd-edition of the VM spec:
2653 //
2654 // methods_default_annotations_typeArray {
2655 // element_value default_value;
2656 // }
2657 //
2658 bool VM_RedefineClasses::rewrite_cp_refs_in_methods_default_annotations(
2659 InstanceKlass* scratch_class) {
2660
2661 for (int i = 0; i < scratch_class->methods()->length(); i++) {
2662 Method* m = scratch_class->methods()->at(i);
2663 AnnotationArray* method_default_annotations = m->constMethod()->default_annotations();
2664 if (method_default_annotations == nullptr
2665 || method_default_annotations->length() == 0) {
2666 // this method does not have any default annotations so skip it
2667 continue;
2668 }
2669
2670 int byte_i = 0; // byte index into method_default_annotations
2671
2672 if (!rewrite_cp_refs_in_element_value(
2673 method_default_annotations, byte_i)) {
2674 log_debug(redefine, class, annotation)("bad default element_value at %d", i);
2675 // propagate failure back to caller
2676 return false;
2677 }
2678 }
2679
2680 return true;
2681 } // end rewrite_cp_refs_in_methods_default_annotations()
2682
2683
2684 // Rewrite constant pool references in a class_type_annotations field.
2685 bool VM_RedefineClasses::rewrite_cp_refs_in_class_type_annotations(
2686 InstanceKlass* scratch_class) {
2687
2688 AnnotationArray* class_type_annotations = scratch_class->class_type_annotations();
2689 if (class_type_annotations == nullptr || class_type_annotations->length() == 0) {
2690 // no class_type_annotations so nothing to do
2691 return true;
2692 }
2693
2694 log_debug(redefine, class, annotation)("class_type_annotations length=%d", class_type_annotations->length());
2695
2696 int byte_i = 0; // byte index into class_type_annotations
2697 return rewrite_cp_refs_in_type_annotations_typeArray(class_type_annotations,
2698 byte_i, "ClassFile");
2699 } // end rewrite_cp_refs_in_class_type_annotations()
2700
2701
2702 // Rewrite constant pool references in a fields_type_annotations field.
2703 bool VM_RedefineClasses::rewrite_cp_refs_in_fields_type_annotations(InstanceKlass* scratch_class) {
2704
2705 Array<AnnotationArray*>* fields_type_annotations = scratch_class->fields_type_annotations();
2706 if (fields_type_annotations == nullptr || fields_type_annotations->length() == 0) {
2707 // no fields_type_annotations so nothing to do
2708 return true;
2709 }
2710
2711 log_debug(redefine, class, annotation)("fields_type_annotations length=%d", fields_type_annotations->length());
2712
2713 for (int i = 0; i < fields_type_annotations->length(); i++) {
2714 AnnotationArray* field_type_annotations = fields_type_annotations->at(i);
2715 if (field_type_annotations == nullptr || field_type_annotations->length() == 0) {
2716 // this field does not have any annotations so skip it
2717 continue;
2718 }
2719
2720 int byte_i = 0; // byte index into field_type_annotations
2721 if (!rewrite_cp_refs_in_type_annotations_typeArray(field_type_annotations,
2722 byte_i, "field_info")) {
2723 log_debug(redefine, class, annotation)("bad field_type_annotations at %d", i);
2724 // propagate failure back to caller
2725 return false;
2726 }
2727 }
2728
2729 return true;
2730 } // end rewrite_cp_refs_in_fields_type_annotations()
2731
2732
2733 // Rewrite constant pool references in a methods_type_annotations field.
2734 bool VM_RedefineClasses::rewrite_cp_refs_in_methods_type_annotations(
2735 InstanceKlass* scratch_class) {
2736
2737 for (int i = 0; i < scratch_class->methods()->length(); i++) {
2738 Method* m = scratch_class->methods()->at(i);
2739 AnnotationArray* method_type_annotations = m->constMethod()->type_annotations();
2740
2741 if (method_type_annotations == nullptr || method_type_annotations->length() == 0) {
2742 // this method does not have any annotations so skip it
2743 continue;
2744 }
2745
2746 log_debug(redefine, class, annotation)("methods type_annotations length=%d", method_type_annotations->length());
2747
2748 int byte_i = 0; // byte index into method_type_annotations
2749 if (!rewrite_cp_refs_in_type_annotations_typeArray(method_type_annotations,
2750 byte_i, "method_info")) {
2751 log_debug(redefine, class, annotation)("bad method_type_annotations at %d", i);
2752 // propagate failure back to caller
2753 return false;
2754 }
2755 }
2756
2757 return true;
2758 } // end rewrite_cp_refs_in_methods_type_annotations()
2759
2760
2761 // Rewrite constant pool references in a type_annotations
2762 // field. This "structure" is adapted from the
2763 // RuntimeVisibleTypeAnnotations_attribute described in
2764 // section 4.7.20 of the Java SE 8 Edition of the VM spec:
2765 //
2766 // type_annotations_typeArray {
2767 // u2 num_annotations;
2768 // type_annotation annotations[num_annotations];
2769 // }
2770 //
2771 bool VM_RedefineClasses::rewrite_cp_refs_in_type_annotations_typeArray(
2772 AnnotationArray* type_annotations_typeArray, int &byte_i_ref,
2773 const char * location_mesg) {
2774
2775 if ((byte_i_ref + 2) > type_annotations_typeArray->length()) {
2776 // not enough room for num_annotations field
2777 log_debug(redefine, class, annotation)("length() is too small for num_annotations field");
2778 return false;
2779 }
2780
2781 u2 num_annotations = Bytes::get_Java_u2((address)
2782 type_annotations_typeArray->adr_at(byte_i_ref));
2783 byte_i_ref += 2;
2784
2785 log_debug(redefine, class, annotation)("num_type_annotations=%d", num_annotations);
2786
2787 int calc_num_annotations = 0;
2788 for (; calc_num_annotations < num_annotations; calc_num_annotations++) {
2789 if (!rewrite_cp_refs_in_type_annotation_struct(type_annotations_typeArray,
2790 byte_i_ref, location_mesg)) {
2791 log_debug(redefine, class, annotation)("bad type_annotation_struct at %d", calc_num_annotations);
2792 // propagate failure back to caller
2793 return false;
2794 }
2795 }
2796 assert(num_annotations == calc_num_annotations, "sanity check");
2797
2798 if (byte_i_ref != type_annotations_typeArray->length()) {
2799 log_debug(redefine, class, annotation)
2800 ("read wrong amount of bytes at end of processing type_annotations_typeArray (%d of %d bytes were read)",
2801 byte_i_ref, type_annotations_typeArray->length());
2802 return false;
2803 }
2804
2805 return true;
2806 } // end rewrite_cp_refs_in_type_annotations_typeArray()
2807
2808
2809 // Rewrite constant pool references in a type_annotation
2810 // field. This "structure" is adapted from the
2811 // RuntimeVisibleTypeAnnotations_attribute described in
2812 // section 4.7.20 of the Java SE 8 Edition of the VM spec:
2813 //
2814 // type_annotation {
2815 // u1 target_type;
2816 // union {
2817 // type_parameter_target;
2818 // supertype_target;
2819 // type_parameter_bound_target;
2820 // empty_target;
2821 // method_formal_parameter_target;
2822 // throws_target;
2823 // localvar_target;
2824 // catch_target;
2825 // offset_target;
2826 // type_argument_target;
2827 // } target_info;
2828 // type_path target_path;
2829 // annotation anno;
2830 // }
2831 //
2832 bool VM_RedefineClasses::rewrite_cp_refs_in_type_annotation_struct(
2833 AnnotationArray* type_annotations_typeArray, int &byte_i_ref,
2834 const char * location_mesg) {
2835
2836 if (!skip_type_annotation_target(type_annotations_typeArray,
2837 byte_i_ref, location_mesg)) {
2838 return false;
2839 }
2840
2841 if (!skip_type_annotation_type_path(type_annotations_typeArray, byte_i_ref)) {
2842 return false;
2843 }
2844
2845 if (!rewrite_cp_refs_in_annotation_struct(type_annotations_typeArray, byte_i_ref)) {
2846 return false;
2847 }
2848
2849 return true;
2850 } // end rewrite_cp_refs_in_type_annotation_struct()
2851
2852
2853 // Read, verify and skip over the target_type and target_info part
2854 // so that rewriting can continue in the later parts of the struct.
2855 //
2856 // u1 target_type;
2857 // union {
2858 // type_parameter_target;
2859 // supertype_target;
2860 // type_parameter_bound_target;
2861 // empty_target;
2862 // method_formal_parameter_target;
2863 // throws_target;
2864 // localvar_target;
2865 // catch_target;
2866 // offset_target;
2867 // type_argument_target;
2868 // } target_info;
2869 //
2870 bool VM_RedefineClasses::skip_type_annotation_target(
2871 AnnotationArray* type_annotations_typeArray, int &byte_i_ref,
2872 const char * location_mesg) {
2873
2874 if ((byte_i_ref + 1) > type_annotations_typeArray->length()) {
2875 // not enough room for a target_type let alone the rest of a type_annotation
2876 log_debug(redefine, class, annotation)("length() is too small for a target_type");
2877 return false;
2878 }
2879
2880 u1 target_type = type_annotations_typeArray->at(byte_i_ref);
2881 byte_i_ref += 1;
2882 log_debug(redefine, class, annotation)("target_type=0x%.2x", target_type);
2883 log_debug(redefine, class, annotation)("location=%s", location_mesg);
2884
2885 // Skip over target_info
2886 switch (target_type) {
2887 case 0x00:
2888 // kind: type parameter declaration of generic class or interface
2889 // location: ClassFile
2890 case 0x01:
2891 // kind: type parameter declaration of generic method or constructor
2892 // location: method_info
2893
2894 {
2895 // struct:
2896 // type_parameter_target {
2897 // u1 type_parameter_index;
2898 // }
2899 //
2900 if ((byte_i_ref + 1) > type_annotations_typeArray->length()) {
2901 log_debug(redefine, class, annotation)("length() is too small for a type_parameter_target");
2902 return false;
2903 }
2904
2905 u1 type_parameter_index = type_annotations_typeArray->at(byte_i_ref);
2906 byte_i_ref += 1;
2907
2908 log_debug(redefine, class, annotation)("type_parameter_target: type_parameter_index=%d", type_parameter_index);
2909 } break;
2910
2911 case 0x10:
2912 // kind: type in extends clause of class or interface declaration
2913 // or in implements clause of interface declaration
2914 // location: ClassFile
2915
2916 {
2917 // struct:
2918 // supertype_target {
2919 // u2 supertype_index;
2920 // }
2921 //
2922 if ((byte_i_ref + 2) > type_annotations_typeArray->length()) {
2923 log_debug(redefine, class, annotation)("length() is too small for a supertype_target");
2924 return false;
2925 }
2926
2927 u2 supertype_index = Bytes::get_Java_u2((address)
2928 type_annotations_typeArray->adr_at(byte_i_ref));
2929 byte_i_ref += 2;
2930
2931 log_debug(redefine, class, annotation)("supertype_target: supertype_index=%d", supertype_index);
2932 } break;
2933
2934 case 0x11:
2935 // kind: type in bound of type parameter declaration of generic class or interface
2936 // location: ClassFile
2937 case 0x12:
2938 // kind: type in bound of type parameter declaration of generic method or constructor
2939 // location: method_info
2940
2941 {
2942 // struct:
2943 // type_parameter_bound_target {
2944 // u1 type_parameter_index;
2945 // u1 bound_index;
2946 // }
2947 //
2948 if ((byte_i_ref + 2) > type_annotations_typeArray->length()) {
2949 log_debug(redefine, class, annotation)("length() is too small for a type_parameter_bound_target");
2950 return false;
2951 }
2952
2953 u1 type_parameter_index = type_annotations_typeArray->at(byte_i_ref);
2954 byte_i_ref += 1;
2955 u1 bound_index = type_annotations_typeArray->at(byte_i_ref);
2956 byte_i_ref += 1;
2957
2958 log_debug(redefine, class, annotation)
2959 ("type_parameter_bound_target: type_parameter_index=%d, bound_index=%d", type_parameter_index, bound_index);
2960 } break;
2961
2962 case 0x13:
2963 // kind: type in field declaration
2964 // location: field_info
2965 case 0x14:
2966 // kind: return type of method, or type of newly constructed object
2967 // location: method_info
2968 case 0x15:
2969 // kind: receiver type of method or constructor
2970 // location: method_info
2971
2972 {
2973 // struct:
2974 // empty_target {
2975 // }
2976 //
2977 log_debug(redefine, class, annotation)("empty_target");
2978 } break;
2979
2980 case 0x16:
2981 // kind: type in formal parameter declaration of method, constructor, or lambda expression
2982 // location: method_info
2983
2984 {
2985 // struct:
2986 // formal_parameter_target {
2987 // u1 formal_parameter_index;
2988 // }
2989 //
2990 if ((byte_i_ref + 1) > type_annotations_typeArray->length()) {
2991 log_debug(redefine, class, annotation)("length() is too small for a formal_parameter_target");
2992 return false;
2993 }
2994
2995 u1 formal_parameter_index = type_annotations_typeArray->at(byte_i_ref);
2996 byte_i_ref += 1;
2997
2998 log_debug(redefine, class, annotation)
2999 ("formal_parameter_target: formal_parameter_index=%d", formal_parameter_index);
3000 } break;
3001
3002 case 0x17:
3003 // kind: type in throws clause of method or constructor
3004 // location: method_info
3005
3006 {
3007 // struct:
3008 // throws_target {
3009 // u2 throws_type_index
3010 // }
3011 //
3012 if ((byte_i_ref + 2) > type_annotations_typeArray->length()) {
3013 log_debug(redefine, class, annotation)("length() is too small for a throws_target");
3014 return false;
3015 }
3016
3017 u2 throws_type_index = Bytes::get_Java_u2((address)
3018 type_annotations_typeArray->adr_at(byte_i_ref));
3019 byte_i_ref += 2;
3020
3021 log_debug(redefine, class, annotation)("throws_target: throws_type_index=%d", throws_type_index);
3022 } break;
3023
3024 case 0x40:
3025 // kind: type in local variable declaration
3026 // location: Code
3027 case 0x41:
3028 // kind: type in resource variable declaration
3029 // location: Code
3030
3031 {
3032 // struct:
3033 // localvar_target {
3034 // u2 table_length;
3035 // struct {
3036 // u2 start_pc;
3037 // u2 length;
3038 // u2 index;
3039 // } table[table_length];
3040 // }
3041 //
3042 if ((byte_i_ref + 2) > type_annotations_typeArray->length()) {
3043 // not enough room for a table_length let alone the rest of a localvar_target
3044 log_debug(redefine, class, annotation)("length() is too small for a localvar_target table_length");
3045 return false;
3046 }
3047
3048 u2 table_length = Bytes::get_Java_u2((address)
3049 type_annotations_typeArray->adr_at(byte_i_ref));
3050 byte_i_ref += 2;
3051
3052 log_debug(redefine, class, annotation)("localvar_target: table_length=%d", table_length);
3053
3054 int table_struct_size = 2 + 2 + 2; // 3 u2 variables per table entry
3055 int table_size = table_length * table_struct_size;
3056
3057 if ((byte_i_ref + table_size) > type_annotations_typeArray->length()) {
3058 // not enough room for a table
3059 log_debug(redefine, class, annotation)("length() is too small for a table array of length %d", table_length);
3060 return false;
3061 }
3062
3063 // Skip over table
3064 byte_i_ref += table_size;
3065 } break;
3066
3067 case 0x42:
3068 // kind: type in exception parameter declaration
3069 // location: Code
3070
3071 {
3072 // struct:
3073 // catch_target {
3074 // u2 exception_table_index;
3075 // }
3076 //
3077 if ((byte_i_ref + 2) > type_annotations_typeArray->length()) {
3078 log_debug(redefine, class, annotation)("length() is too small for a catch_target");
3079 return false;
3080 }
3081
3082 u2 exception_table_index = Bytes::get_Java_u2((address)
3083 type_annotations_typeArray->adr_at(byte_i_ref));
3084 byte_i_ref += 2;
3085
3086 log_debug(redefine, class, annotation)("catch_target: exception_table_index=%d", exception_table_index);
3087 } break;
3088
3089 case 0x43:
3090 // kind: type in instanceof expression
3091 // location: Code
3092 case 0x44:
3093 // kind: type in new expression
3094 // location: Code
3095 case 0x45:
3096 // kind: type in method reference expression using ::new
3097 // location: Code
3098 case 0x46:
3099 // kind: type in method reference expression using ::Identifier
3100 // location: Code
3101
3102 {
3103 // struct:
3104 // offset_target {
3105 // u2 offset;
3106 // }
3107 //
3108 if ((byte_i_ref + 2) > type_annotations_typeArray->length()) {
3109 log_debug(redefine, class, annotation)("length() is too small for a offset_target");
3110 return false;
3111 }
3112
3113 u2 offset = Bytes::get_Java_u2((address)
3114 type_annotations_typeArray->adr_at(byte_i_ref));
3115 byte_i_ref += 2;
3116
3117 log_debug(redefine, class, annotation)("offset_target: offset=%d", offset);
3118 } break;
3119
3120 case 0x47:
3121 // kind: type in cast expression
3122 // location: Code
3123 case 0x48:
3124 // kind: type argument for generic constructor in new expression or
3125 // explicit constructor invocation statement
3126 // location: Code
3127 case 0x49:
3128 // kind: type argument for generic method in method invocation expression
3129 // location: Code
3130 case 0x4A:
3131 // kind: type argument for generic constructor in method reference expression using ::new
3132 // location: Code
3133 case 0x4B:
3134 // kind: type argument for generic method in method reference expression using ::Identifier
3135 // location: Code
3136
3137 {
3138 // struct:
3139 // type_argument_target {
3140 // u2 offset;
3141 // u1 type_argument_index;
3142 // }
3143 //
3144 if ((byte_i_ref + 3) > type_annotations_typeArray->length()) {
3145 log_debug(redefine, class, annotation)("length() is too small for a type_argument_target");
3146 return false;
3147 }
3148
3149 u2 offset = Bytes::get_Java_u2((address)
3150 type_annotations_typeArray->adr_at(byte_i_ref));
3151 byte_i_ref += 2;
3152 u1 type_argument_index = type_annotations_typeArray->at(byte_i_ref);
3153 byte_i_ref += 1;
3154
3155 log_debug(redefine, class, annotation)
3156 ("type_argument_target: offset=%d, type_argument_index=%d", offset, type_argument_index);
3157 } break;
3158
3159 default:
3160 log_debug(redefine, class, annotation)("unknown target_type");
3161 #ifdef ASSERT
3162 ShouldNotReachHere();
3163 #endif
3164 return false;
3165 }
3166
3167 return true;
3168 } // end skip_type_annotation_target()
3169
3170
3171 // Read, verify and skip over the type_path part so that rewriting
3172 // can continue in the later parts of the struct.
3173 //
3174 // type_path {
3175 // u1 path_length;
3176 // {
3177 // u1 type_path_kind;
3178 // u1 type_argument_index;
3179 // } path[path_length];
3180 // }
3181 //
3182 bool VM_RedefineClasses::skip_type_annotation_type_path(
3183 AnnotationArray* type_annotations_typeArray, int &byte_i_ref) {
3184
3185 if ((byte_i_ref + 1) > type_annotations_typeArray->length()) {
3186 // not enough room for a path_length let alone the rest of the type_path
3187 log_debug(redefine, class, annotation)("length() is too small for a type_path");
3188 return false;
3189 }
3190
3191 u1 path_length = type_annotations_typeArray->at(byte_i_ref);
3192 byte_i_ref += 1;
3193
3194 log_debug(redefine, class, annotation)("type_path: path_length=%d", path_length);
3195
3196 int calc_path_length = 0;
3197 for (; calc_path_length < path_length; calc_path_length++) {
3198 if ((byte_i_ref + 1 + 1) > type_annotations_typeArray->length()) {
3199 // not enough room for a path
3200 log_debug(redefine, class, annotation)
3201 ("length() is too small for path entry %d of %d", calc_path_length, path_length);
3202 return false;
3203 }
3204
3205 u1 type_path_kind = type_annotations_typeArray->at(byte_i_ref);
3206 byte_i_ref += 1;
3207 u1 type_argument_index = type_annotations_typeArray->at(byte_i_ref);
3208 byte_i_ref += 1;
3209
3210 log_debug(redefine, class, annotation)
3211 ("type_path: path[%d]: type_path_kind=%d, type_argument_index=%d",
3212 calc_path_length, type_path_kind, type_argument_index);
3213
3214 if (type_path_kind > 3 || (type_path_kind != 3 && type_argument_index != 0)) {
3215 // not enough room for a path
3216 log_debug(redefine, class, annotation)("inconsistent type_path values");
3217 return false;
3218 }
3219 }
3220 assert(path_length == calc_path_length, "sanity check");
3221
3222 return true;
3223 } // end skip_type_annotation_type_path()
3224
3225
3226 // Rewrite constant pool references in the method's stackmap table.
3227 // These "structures" are adapted from the StackMapTable_attribute that
3228 // is described in section 4.8.4 of the 6.0 version of the VM spec
3229 // (dated 2005.10.26):
3230 // file:///net/quincunx.sfbay/export/gbracha/ClassFile-Java6.pdf
3231 //
3232 // stack_map {
3233 // u2 number_of_entries;
3234 // stack_map_frame entries[number_of_entries];
3235 // }
3236 //
3237 void VM_RedefineClasses::rewrite_cp_refs_in_stack_map_table(
3238 const methodHandle& method) {
3239
3240 if (!method->has_stackmap_table()) {
3241 return;
3242 }
3243
3244 AnnotationArray* stackmap_data = method->stackmap_data();
3245 address stackmap_p = (address)stackmap_data->adr_at(0);
3246 address stackmap_end = stackmap_p + stackmap_data->length();
3247
3248 assert(stackmap_p + 2 <= stackmap_end, "no room for number_of_entries");
3249 u2 number_of_entries = Bytes::get_Java_u2(stackmap_p);
3250 stackmap_p += 2;
3251
3252 log_debug(redefine, class, stackmap)("number_of_entries=%u", number_of_entries);
3253
3254 // walk through each stack_map_frame
3255 u2 calc_number_of_entries = 0;
3256 for (; calc_number_of_entries < number_of_entries; calc_number_of_entries++) {
3257 // The stack_map_frame structure is a u1 frame_type followed by
3258 // 0 or more bytes of data:
3259 //
3260 // union stack_map_frame {
3261 // same_frame;
3262 // same_locals_1_stack_item_frame;
3263 // same_locals_1_stack_item_frame_extended;
3264 // chop_frame;
3265 // same_frame_extended;
3266 // append_frame;
3267 // full_frame;
3268 // }
3269
3270 assert(stackmap_p + 1 <= stackmap_end, "no room for frame_type");
3271 u1 frame_type = *stackmap_p;
3272 stackmap_p++;
3273
3274 // same_frame {
3275 // u1 frame_type = SAME; /* 0-63 */
3276 // }
3277 if (frame_type <= 63) {
3278 // nothing more to do for same_frame
3279 }
3280
3281 // same_locals_1_stack_item_frame {
3282 // u1 frame_type = SAME_LOCALS_1_STACK_ITEM; /* 64-127 */
3283 // verification_type_info stack[1];
3284 // }
3285 else if (frame_type >= 64 && frame_type <= 127) {
3286 rewrite_cp_refs_in_verification_type_info(stackmap_p, stackmap_end,
3287 calc_number_of_entries, frame_type);
3288 }
3289
3290 // reserved for future use
3291 else if (frame_type >= 128 && frame_type <= 246) {
3292 // nothing more to do for reserved frame_types
3293 }
3294
3295 // same_locals_1_stack_item_frame_extended {
3296 // u1 frame_type = SAME_LOCALS_1_STACK_ITEM_EXTENDED; /* 247 */
3297 // u2 offset_delta;
3298 // verification_type_info stack[1];
3299 // }
3300 else if (frame_type == 247) {
3301 stackmap_p += 2;
3302 rewrite_cp_refs_in_verification_type_info(stackmap_p, stackmap_end,
3303 calc_number_of_entries, frame_type);
3304 }
3305
3306 // chop_frame {
3307 // u1 frame_type = CHOP; /* 248-250 */
3308 // u2 offset_delta;
3309 // }
3310 else if (frame_type >= 248 && frame_type <= 250) {
3311 stackmap_p += 2;
3312 }
3313
3314 // same_frame_extended {
3315 // u1 frame_type = SAME_FRAME_EXTENDED; /* 251*/
3316 // u2 offset_delta;
3317 // }
3318 else if (frame_type == 251) {
3319 stackmap_p += 2;
3320 }
3321
3322 // append_frame {
3323 // u1 frame_type = APPEND; /* 252-254 */
3324 // u2 offset_delta;
3325 // verification_type_info locals[frame_type - 251];
3326 // }
3327 else if (frame_type >= 252 && frame_type <= 254) {
3328 assert(stackmap_p + 2 <= stackmap_end,
3329 "no room for offset_delta");
3330 stackmap_p += 2;
3331 u1 len = frame_type - 251;
3332 for (u1 i = 0; i < len; i++) {
3333 rewrite_cp_refs_in_verification_type_info(stackmap_p, stackmap_end,
3334 calc_number_of_entries, frame_type);
3335 }
3336 }
3337
3338 // full_frame {
3339 // u1 frame_type = FULL_FRAME; /* 255 */
3340 // u2 offset_delta;
3341 // u2 number_of_locals;
3342 // verification_type_info locals[number_of_locals];
3343 // u2 number_of_stack_items;
3344 // verification_type_info stack[number_of_stack_items];
3345 // }
3346 else if (frame_type == 255) {
3347 assert(stackmap_p + 2 + 2 <= stackmap_end,
3348 "no room for smallest full_frame");
3349 stackmap_p += 2;
3350
3351 u2 number_of_locals = Bytes::get_Java_u2(stackmap_p);
3352 stackmap_p += 2;
3353
3354 for (u2 locals_i = 0; locals_i < number_of_locals; locals_i++) {
3355 rewrite_cp_refs_in_verification_type_info(stackmap_p, stackmap_end,
3356 calc_number_of_entries, frame_type);
3357 }
3358
3359 // Use the largest size for the number_of_stack_items, but only get
3360 // the right number of bytes.
3361 u2 number_of_stack_items = Bytes::get_Java_u2(stackmap_p);
3362 stackmap_p += 2;
3363
3364 for (u2 stack_i = 0; stack_i < number_of_stack_items; stack_i++) {
3365 rewrite_cp_refs_in_verification_type_info(stackmap_p, stackmap_end,
3366 calc_number_of_entries, frame_type);
3367 }
3368 }
3369 } // end while there is a stack_map_frame
3370 assert(number_of_entries == calc_number_of_entries, "sanity check");
3371 } // end rewrite_cp_refs_in_stack_map_table()
3372
3373
3374 // Rewrite constant pool references in the verification type info
3375 // portion of the method's stackmap table. These "structures" are
3376 // adapted from the StackMapTable_attribute that is described in
3377 // section 4.8.4 of the 6.0 version of the VM spec (dated 2005.10.26):
3378 // file:///net/quincunx.sfbay/export/gbracha/ClassFile-Java6.pdf
3379 //
3380 // The verification_type_info structure is a u1 tag followed by 0 or
3381 // more bytes of data:
3382 //
3383 // union verification_type_info {
3384 // Top_variable_info;
3385 // Integer_variable_info;
3386 // Float_variable_info;
3387 // Long_variable_info;
3388 // Double_variable_info;
3389 // Null_variable_info;
3390 // UninitializedThis_variable_info;
3391 // Object_variable_info;
3392 // Uninitialized_variable_info;
3393 // }
3394 //
3395 void VM_RedefineClasses::rewrite_cp_refs_in_verification_type_info(
3396 address& stackmap_p_ref, address stackmap_end, u2 frame_i,
3397 u1 frame_type) {
3398
3399 assert(stackmap_p_ref + 1 <= stackmap_end, "no room for tag");
3400 u1 tag = *stackmap_p_ref;
3401 stackmap_p_ref++;
3402
3403 switch (tag) {
3404 // Top_variable_info {
3405 // u1 tag = ITEM_Top; /* 0 */
3406 // }
3407 // verificationType.hpp has zero as ITEM_Bogus instead of ITEM_Top
3408 case 0: // fall through
3409
3410 // Integer_variable_info {
3411 // u1 tag = ITEM_Integer; /* 1 */
3412 // }
3413 case ITEM_Integer: // fall through
3414
3415 // Float_variable_info {
3416 // u1 tag = ITEM_Float; /* 2 */
3417 // }
3418 case ITEM_Float: // fall through
3419
3420 // Double_variable_info {
3421 // u1 tag = ITEM_Double; /* 3 */
3422 // }
3423 case ITEM_Double: // fall through
3424
3425 // Long_variable_info {
3426 // u1 tag = ITEM_Long; /* 4 */
3427 // }
3428 case ITEM_Long: // fall through
3429
3430 // Null_variable_info {
3431 // u1 tag = ITEM_Null; /* 5 */
3432 // }
3433 case ITEM_Null: // fall through
3434
3435 // UninitializedThis_variable_info {
3436 // u1 tag = ITEM_UninitializedThis; /* 6 */
3437 // }
3438 case ITEM_UninitializedThis:
3439 // nothing more to do for the above tag types
3440 break;
3441
3442 // Object_variable_info {
3443 // u1 tag = ITEM_Object; /* 7 */
3444 // u2 cpool_index;
3445 // }
3446 case ITEM_Object:
3447 {
3448 assert(stackmap_p_ref + 2 <= stackmap_end, "no room for cpool_index");
3449 u2 cpool_index = Bytes::get_Java_u2(stackmap_p_ref);
3450 u2 new_cp_index = find_new_index(cpool_index);
3451 if (new_cp_index != 0) {
3452 log_debug(redefine, class, stackmap)("mapped old cpool_index=%d", cpool_index);
3453 Bytes::put_Java_u2(stackmap_p_ref, new_cp_index);
3454 cpool_index = new_cp_index;
3455 }
3456 stackmap_p_ref += 2;
3457
3458 log_debug(redefine, class, stackmap)
3459 ("frame_i=%u, frame_type=%u, cpool_index=%d", frame_i, frame_type, cpool_index);
3460 } break;
3461
3462 // Uninitialized_variable_info {
3463 // u1 tag = ITEM_Uninitialized; /* 8 */
3464 // u2 offset;
3465 // }
3466 case ITEM_Uninitialized:
3467 assert(stackmap_p_ref + 2 <= stackmap_end, "no room for offset");
3468 stackmap_p_ref += 2;
3469 break;
3470
3471 default:
3472 log_debug(redefine, class, stackmap)("frame_i=%u, frame_type=%u, bad tag=0x%x", frame_i, frame_type, tag);
3473 ShouldNotReachHere();
3474 break;
3475 } // end switch (tag)
3476 } // end rewrite_cp_refs_in_verification_type_info()
3477
3478
3479 // Change the constant pool associated with klass scratch_class to scratch_cp.
3480 // scratch_cp_length elements are copied from scratch_cp to a smaller constant pool
3481 // and the smaller constant pool is associated with scratch_class.
3482 void VM_RedefineClasses::set_new_constant_pool(
3483 ClassLoaderData* loader_data,
3484 InstanceKlass* scratch_class, constantPoolHandle scratch_cp,
3485 int scratch_cp_length, TRAPS) {
3486 assert(scratch_cp->length() >= scratch_cp_length, "sanity check");
3487
3488 // scratch_cp is a merged constant pool and has enough space for a
3489 // worst case merge situation. We want to associate the minimum
3490 // sized constant pool with the klass to save space.
3491 ConstantPool* cp = ConstantPool::allocate(loader_data, scratch_cp_length, CHECK);
3492 constantPoolHandle smaller_cp(THREAD, cp);
3493
3494 // preserve version() value in the smaller copy
3495 int version = scratch_cp->version();
3496 assert(version != 0, "sanity check");
3497 smaller_cp->set_version(version);
3498
3499 // attach klass to new constant pool
3500 // reference to the cp holder is needed for copy_operands()
3501 smaller_cp->set_pool_holder(scratch_class);
3502
3503 smaller_cp->copy_fields(scratch_cp());
3504
3505 scratch_cp->copy_cp_to(1, scratch_cp_length - 1, smaller_cp, 1, THREAD);
3506 if (HAS_PENDING_EXCEPTION) {
3507 // Exception is handled in the caller
3508 loader_data->add_to_deallocate_list(smaller_cp());
3509 return;
3510 }
3511 scratch_cp = smaller_cp;
3512
3513 // attach new constant pool to klass
3514 scratch_class->set_constants(scratch_cp());
3515 scratch_cp->initialize_unresolved_klasses(loader_data, CHECK);
3516
3517 int i; // for portability
3518
3519 // update each field in klass to use new constant pool indices as needed
3520 int java_fields;
3521 int injected_fields;
3522 bool update_required = false;
3523 GrowableArray<FieldInfo>* fields = FieldInfoStream::create_FieldInfoArray(scratch_class->fieldinfo_stream(), &java_fields, &injected_fields);
3524 for (int i = 0; i < java_fields; i++) {
3525 FieldInfo* fi = fields->adr_at(i);
3526 jshort cur_index = fi->name_index();
3527 jshort new_index = find_new_index(cur_index);
3528 if (new_index != 0) {
3529 log_trace(redefine, class, constantpool)("field-name_index change: %d to %d", cur_index, new_index);
3530 fi->set_name_index(new_index);
3531 update_required = true;
3532 }
3533 cur_index = fi->signature_index();
3534 new_index = find_new_index(cur_index);
3535 if (new_index != 0) {
3536 log_trace(redefine, class, constantpool)("field-signature_index change: %d to %d", cur_index, new_index);
3537 fi->set_signature_index(new_index);
3538 update_required = true;
3539 }
3540 cur_index = fi->initializer_index();
3541 new_index = find_new_index(cur_index);
3542 if (new_index != 0) {
3543 log_trace(redefine, class, constantpool)("field-initval_index change: %d to %d", cur_index, new_index);
3544 fi->set_initializer_index(new_index);
3545 update_required = true;
3546 }
3547 cur_index = fi->generic_signature_index();
3548 new_index = find_new_index(cur_index);
3549 if (new_index != 0) {
3550 log_trace(redefine, class, constantpool)("field-generic_signature change: %d to %d", cur_index, new_index);
3551 fi->set_generic_signature_index(new_index);
3552 update_required = true;
3553 }
3554 }
3555 if (update_required) {
3556 Array<u1>* old_stream = scratch_class->fieldinfo_stream();
3557 assert(fields->length() == (java_fields + injected_fields), "Must be");
3558 Array<u1>* new_fis = FieldInfoStream::create_FieldInfoStream(fields, java_fields, injected_fields, scratch_class->class_loader_data(), CHECK);
3559 scratch_class->set_fieldinfo_stream(new_fis);
3560 MetadataFactory::free_array<u1>(scratch_class->class_loader_data(), old_stream);
3561 }
3562
3563 // Update constant pool indices in the inner classes info to use
3564 // new constant indices as needed. The inner classes info is a
3565 // quadruple:
3566 // (inner_class_info, outer_class_info, inner_name, inner_access_flags)
3567 InnerClassesIterator iter(scratch_class);
3568 for (; !iter.done(); iter.next()) {
3569 int cur_index = iter.inner_class_info_index();
3570 if (cur_index == 0) {
3571 continue; // JVM spec. allows null inner class refs so skip it
3572 }
3573 u2 new_index = find_new_index(cur_index);
3574 if (new_index != 0) {
3575 log_trace(redefine, class, constantpool)("inner_class_info change: %d to %d", cur_index, new_index);
3576 iter.set_inner_class_info_index(new_index);
3577 }
3578 cur_index = iter.outer_class_info_index();
3579 new_index = find_new_index(cur_index);
3580 if (new_index != 0) {
3581 log_trace(redefine, class, constantpool)("outer_class_info change: %d to %d", cur_index, new_index);
3582 iter.set_outer_class_info_index(new_index);
3583 }
3584 cur_index = iter.inner_name_index();
3585 new_index = find_new_index(cur_index);
3586 if (new_index != 0) {
3587 log_trace(redefine, class, constantpool)("inner_name change: %d to %d", cur_index, new_index);
3588 iter.set_inner_name_index(new_index);
3589 }
3590 } // end for each inner class
3591
3592 // Attach each method in klass to the new constant pool and update
3593 // to use new constant pool indices as needed:
3594 Array<Method*>* methods = scratch_class->methods();
3595 for (i = methods->length() - 1; i >= 0; i--) {
3596 methodHandle method(THREAD, methods->at(i));
3597 method->set_constants(scratch_cp());
3598
3599 u2 new_index = find_new_index(method->name_index());
3600 if (new_index != 0) {
3601 log_trace(redefine, class, constantpool)
3602 ("method-name_index change: %d to %d", method->name_index(), new_index);
3603 method->set_name_index(new_index);
3604 }
3605 new_index = find_new_index(method->signature_index());
3606 if (new_index != 0) {
3607 log_trace(redefine, class, constantpool)
3608 ("method-signature_index change: %d to %d", method->signature_index(), new_index);
3609 method->set_signature_index(new_index);
3610 }
3611 new_index = find_new_index(method->generic_signature_index());
3612 if (new_index != 0) {
3613 log_trace(redefine, class, constantpool)
3614 ("method-generic_signature_index change: %d to %d", method->generic_signature_index(), new_index);
3615 method->constMethod()->set_generic_signature_index(new_index);
3616 }
3617
3618 // Update constant pool indices in the method's checked exception
3619 // table to use new constant indices as needed.
3620 int cext_length = method->checked_exceptions_length();
3621 if (cext_length > 0) {
3622 CheckedExceptionElement * cext_table =
3623 method->checked_exceptions_start();
3624 for (int j = 0; j < cext_length; j++) {
3625 int cur_index = cext_table[j].class_cp_index;
3626 int new_index = find_new_index(cur_index);
3627 if (new_index != 0) {
3628 log_trace(redefine, class, constantpool)("cext-class_cp_index change: %d to %d", cur_index, new_index);
3629 cext_table[j].class_cp_index = (u2)new_index;
3630 }
3631 } // end for each checked exception table entry
3632 } // end if there are checked exception table entries
3633
3634 // Update each catch type index in the method's exception table
3635 // to use new constant pool indices as needed. The exception table
3636 // holds quadruple entries of the form:
3637 // (beg_bci, end_bci, handler_bci, klass_index)
3638
3639 ExceptionTable ex_table(method());
3640 int ext_length = ex_table.length();
3641
3642 for (int j = 0; j < ext_length; j ++) {
3643 int cur_index = ex_table.catch_type_index(j);
3644 u2 new_index = find_new_index(cur_index);
3645 if (new_index != 0) {
3646 log_trace(redefine, class, constantpool)("ext-klass_index change: %d to %d", cur_index, new_index);
3647 ex_table.set_catch_type_index(j, new_index);
3648 }
3649 } // end for each exception table entry
3650
3651 // Update constant pool indices in the method's local variable
3652 // table to use new constant indices as needed. The local variable
3653 // table hold sextuple entries of the form:
3654 // (start_pc, length, name_index, descriptor_index, signature_index, slot)
3655 int lvt_length = method->localvariable_table_length();
3656 if (lvt_length > 0) {
3657 LocalVariableTableElement * lv_table =
3658 method->localvariable_table_start();
3659 for (int j = 0; j < lvt_length; j++) {
3660 int cur_index = lv_table[j].name_cp_index;
3661 int new_index = find_new_index(cur_index);
3662 if (new_index != 0) {
3663 log_trace(redefine, class, constantpool)("lvt-name_cp_index change: %d to %d", cur_index, new_index);
3664 lv_table[j].name_cp_index = (u2)new_index;
3665 }
3666 cur_index = lv_table[j].descriptor_cp_index;
3667 new_index = find_new_index(cur_index);
3668 if (new_index != 0) {
3669 log_trace(redefine, class, constantpool)("lvt-descriptor_cp_index change: %d to %d", cur_index, new_index);
3670 lv_table[j].descriptor_cp_index = (u2)new_index;
3671 }
3672 cur_index = lv_table[j].signature_cp_index;
3673 new_index = find_new_index(cur_index);
3674 if (new_index != 0) {
3675 log_trace(redefine, class, constantpool)("lvt-signature_cp_index change: %d to %d", cur_index, new_index);
3676 lv_table[j].signature_cp_index = (u2)new_index;
3677 }
3678 } // end for each local variable table entry
3679 } // end if there are local variable table entries
3680
3681 // Update constant pool indices in the method's method_parameters.
3682 int mp_length = method->method_parameters_length();
3683 if (mp_length > 0) {
3684 MethodParametersElement* elem = method->method_parameters_start();
3685 for (int j = 0; j < mp_length; j++) {
3686 const int cp_index = elem[j].name_cp_index;
3687 const int new_cp_index = find_new_index(cp_index);
3688 if (new_cp_index != 0) {
3689 elem[j].name_cp_index = (u2)new_cp_index;
3690 }
3691 }
3692 }
3693
3694 rewrite_cp_refs_in_stack_map_table(method);
3695 } // end for each method
3696 } // end set_new_constant_pool()
3697
3698
3699 // Unevolving classes may point to methods of the_class directly
3700 // from their constant pool caches, itables, and/or vtables. We
3701 // use the ClassLoaderDataGraph::classes_do() facility and this helper
3702 // to fix up these pointers. MethodData also points to old methods and
3703 // must be cleaned.
3704
3705 // Adjust cpools and vtables closure
3706 void VM_RedefineClasses::AdjustAndCleanMetadata::do_klass(Klass* k) {
3707
3708 // This is a very busy routine. We don't want too much tracing
3709 // printed out.
3710 bool trace_name_printed = false;
3711
3712 // If the class being redefined is java.lang.Object, we need to fix all
3713 // array class vtables also. The _has_redefined_Object flag is global.
3714 // Once the java.lang.Object has been redefined (by the current or one
3715 // of the previous VM_RedefineClasses operations) we have to always
3716 // adjust method entries for array classes.
3717 if (k->is_array_klass() && _has_redefined_Object) {
3718 k->vtable().adjust_method_entries(&trace_name_printed);
3719
3720 } else if (k->is_instance_klass()) {
3721 HandleMark hm(_thread);
3722 InstanceKlass *ik = InstanceKlass::cast(k);
3723
3724 // Clean MethodData of this class's methods so they don't refer to
3725 // old methods that are no longer running.
3726 Array<Method*>* methods = ik->methods();
3727 int num_methods = methods->length();
3728 for (int index = 0; index < num_methods; ++index) {
3729 if (methods->at(index)->method_data() != nullptr) {
3730 methods->at(index)->method_data()->clean_weak_method_links();
3731 }
3732 }
3733
3734 // Adjust all vtables, default methods and itables, to clean out old methods.
3735 ResourceMark rm(_thread);
3736 if (ik->vtable_length() > 0) {
3737 ik->vtable().adjust_method_entries(&trace_name_printed);
3738 ik->adjust_default_methods(&trace_name_printed);
3739 }
3740
3741 if (ik->itable_length() > 0) {
3742 ik->itable().adjust_method_entries(&trace_name_printed);
3743 }
3744
3745 // The constant pools in other classes (other_cp) can refer to
3746 // old methods. We have to update method information in
3747 // other_cp's cache. If other_cp has a previous version, then we
3748 // have to repeat the process for each previous version. The
3749 // constant pool cache holds the Method*s for non-virtual
3750 // methods and for virtual, final methods.
3751 //
3752 // Special case: if the current class is being redefined by the current
3753 // VM_RedefineClasses operation, then new_cp has already been attached
3754 // to the_class and old_cp has already been added as a previous version.
3755 // The new_cp doesn't have any cached references to old methods so it
3756 // doesn't need to be updated and we could optimize by skipping it.
3757 // However, the current class can be marked as being redefined by another
3758 // VM_RedefineClasses operation which has already executed its doit_prologue
3759 // and needs cpcache method entries adjusted. For simplicity, the cpcache
3760 // update is done unconditionally. It should result in doing nothing for
3761 // classes being redefined by the current VM_RedefineClasses operation.
3762 // Method entries in the previous version(s) are adjusted as well.
3763 ConstantPoolCache* cp_cache;
3764
3765 // this klass' constant pool cache may need adjustment
3766 ConstantPool* other_cp = ik->constants();
3767 cp_cache = other_cp->cache();
3768 if (cp_cache != nullptr) {
3769 cp_cache->adjust_method_entries(&trace_name_printed);
3770 }
3771
3772 // the previous versions' constant pool caches may need adjustment
3773 for (InstanceKlass* pv_node = ik->previous_versions();
3774 pv_node != nullptr;
3775 pv_node = pv_node->previous_versions()) {
3776 cp_cache = pv_node->constants()->cache();
3777 if (cp_cache != nullptr) {
3778 cp_cache->adjust_method_entries(&trace_name_printed);
3779 }
3780 }
3781 }
3782 }
3783
3784 void VM_RedefineClasses::update_jmethod_ids() {
3785 for (int j = 0; j < _matching_methods_length; ++j) {
3786 Method* old_method = _matching_old_methods[j];
3787 jmethodID jmid = old_method->find_jmethod_id_or_null();
3788 if (jmid != nullptr) {
3789 // There is a jmethodID, change it to point to the new method
3790 Method* new_method = _matching_new_methods[j];
3791 Method::change_method_associated_with_jmethod_id(jmid, new_method);
3792 assert(Method::resolve_jmethod_id(jmid) == _matching_new_methods[j],
3793 "should be replaced");
3794 }
3795 }
3796 }
3797
3798 int VM_RedefineClasses::check_methods_and_mark_as_obsolete() {
3799 int emcp_method_count = 0;
3800 int obsolete_count = 0;
3801 int old_index = 0;
3802 for (int j = 0; j < _matching_methods_length; ++j, ++old_index) {
3803 Method* old_method = _matching_old_methods[j];
3804 Method* new_method = _matching_new_methods[j];
3805 Method* old_array_method;
3806
3807 // Maintain an old_index into the _old_methods array by skipping
3808 // deleted methods
3809 while ((old_array_method = _old_methods->at(old_index)) != old_method) {
3810 ++old_index;
3811 }
3812
3813 if (MethodComparator::methods_EMCP(old_method, new_method)) {
3814 // The EMCP definition from JSR-163 requires the bytecodes to be
3815 // the same with the exception of constant pool indices which may
3816 // differ. However, the constants referred to by those indices
3817 // must be the same.
3818 //
3819 // We use methods_EMCP() for comparison since constant pool
3820 // merging can remove duplicate constant pool entries that were
3821 // present in the old method and removed from the rewritten new
3822 // method. A faster binary comparison function would consider the
3823 // old and new methods to be different when they are actually
3824 // EMCP.
3825 //
3826 // The old and new methods are EMCP and you would think that we
3827 // could get rid of one of them here and now and save some space.
3828 // However, the concept of EMCP only considers the bytecodes and
3829 // the constant pool entries in the comparison. Other things,
3830 // e.g., the line number table (LNT) or the local variable table
3831 // (LVT) don't count in the comparison. So the new (and EMCP)
3832 // method can have a new LNT that we need so we can't just
3833 // overwrite the new method with the old method.
3834 //
3835 // When this routine is called, we have already attached the new
3836 // methods to the_class so the old methods are effectively
3837 // overwritten. However, if an old method is still executing,
3838 // then the old method cannot be collected until sometime after
3839 // the old method call has returned. So the overwriting of old
3840 // methods by new methods will save us space except for those
3841 // (hopefully few) old methods that are still executing.
3842 //
3843 // A method refers to a ConstMethod* and this presents another
3844 // possible avenue to space savings. The ConstMethod* in the
3845 // new method contains possibly new attributes (LNT, LVT, etc).
3846 // At first glance, it seems possible to save space by replacing
3847 // the ConstMethod* in the old method with the ConstMethod*
3848 // from the new method. The old and new methods would share the
3849 // same ConstMethod* and we would save the space occupied by
3850 // the old ConstMethod*. However, the ConstMethod* contains
3851 // a back reference to the containing method. Sharing the
3852 // ConstMethod* between two methods could lead to confusion in
3853 // the code that uses the back reference. This would lead to
3854 // brittle code that could be broken in non-obvious ways now or
3855 // in the future.
3856 //
3857 // Another possibility is to copy the ConstMethod* from the new
3858 // method to the old method and then overwrite the new method with
3859 // the old method. Since the ConstMethod* contains the bytecodes
3860 // for the method embedded in the oop, this option would change
3861 // the bytecodes out from under any threads executing the old
3862 // method and make the thread's bcp invalid. Since EMCP requires
3863 // that the bytecodes be the same modulo constant pool indices, it
3864 // is straight forward to compute the correct new bcp in the new
3865 // ConstMethod* from the old bcp in the old ConstMethod*. The
3866 // time consuming part would be searching all the frames in all
3867 // of the threads to find all of the calls to the old method.
3868 //
3869 // It looks like we will have to live with the limited savings
3870 // that we get from effectively overwriting the old methods
3871 // when the new methods are attached to the_class.
3872
3873 // Count number of methods that are EMCP. The method will be marked
3874 // old but not obsolete if it is EMCP.
3875 emcp_method_count++;
3876
3877 // An EMCP method is _not_ obsolete. An obsolete method has a
3878 // different jmethodID than the current method. An EMCP method
3879 // has the same jmethodID as the current method. Having the
3880 // same jmethodID for all EMCP versions of a method allows for
3881 // a consistent view of the EMCP methods regardless of which
3882 // EMCP method you happen to have in hand. For example, a
3883 // breakpoint set in one EMCP method will work for all EMCP
3884 // versions of the method including the current one.
3885 } else {
3886 // mark obsolete methods as such
3887 old_method->set_is_obsolete();
3888 obsolete_count++;
3889
3890 // obsolete methods need a unique idnum so they become new entries in
3891 // the jmethodID cache in InstanceKlass
3892 assert(old_method->method_idnum() == new_method->method_idnum(), "must match");
3893 u2 num = InstanceKlass::cast(_the_class)->next_method_idnum();
3894 if (num != ConstMethod::UNSET_IDNUM) {
3895 old_method->set_method_idnum(num);
3896 }
3897
3898 // With tracing we try not to "yack" too much. The position of
3899 // this trace assumes there are fewer obsolete methods than
3900 // EMCP methods.
3901 if (log_is_enabled(Trace, redefine, class, obsolete, mark)) {
3902 ResourceMark rm;
3903 log_trace(redefine, class, obsolete, mark)
3904 ("mark %s(%s) as obsolete", old_method->name()->as_C_string(), old_method->signature()->as_C_string());
3905 }
3906 }
3907 old_method->set_is_old();
3908 }
3909 for (int i = 0; i < _deleted_methods_length; ++i) {
3910 Method* old_method = _deleted_methods[i];
3911
3912 assert(!old_method->has_vtable_index(),
3913 "cannot delete methods with vtable entries");;
3914
3915 // Mark all deleted methods as old, obsolete and deleted
3916 old_method->set_is_deleted();
3917 old_method->set_is_old();
3918 old_method->set_is_obsolete();
3919 ++obsolete_count;
3920 // With tracing we try not to "yack" too much. The position of
3921 // this trace assumes there are fewer obsolete methods than
3922 // EMCP methods.
3923 if (log_is_enabled(Trace, redefine, class, obsolete, mark)) {
3924 ResourceMark rm;
3925 log_trace(redefine, class, obsolete, mark)
3926 ("mark deleted %s(%s) as obsolete", old_method->name()->as_C_string(), old_method->signature()->as_C_string());
3927 }
3928 }
3929 assert((emcp_method_count + obsolete_count) == _old_methods->length(),
3930 "sanity check");
3931 log_trace(redefine, class, obsolete, mark)("EMCP_cnt=%d, obsolete_cnt=%d", emcp_method_count, obsolete_count);
3932 return emcp_method_count;
3933 }
3934
3935 // This internal class transfers the native function registration from old methods
3936 // to new methods. It is designed to handle both the simple case of unchanged
3937 // native methods and the complex cases of native method prefixes being added and/or
3938 // removed.
3939 // It expects only to be used during the VM_RedefineClasses op (a safepoint).
3940 //
3941 // This class is used after the new methods have been installed in "the_class".
3942 //
3943 // So, for example, the following must be handled. Where 'm' is a method and
3944 // a number followed by an underscore is a prefix.
3945 //
3946 // Old Name New Name
3947 // Simple transfer to new method m -> m
3948 // Add prefix m -> 1_m
3949 // Remove prefix 1_m -> m
3950 // Simultaneous add of prefixes m -> 3_2_1_m
3951 // Simultaneous removal of prefixes 3_2_1_m -> m
3952 // Simultaneous add and remove 1_m -> 2_m
3953 // Same, caused by prefix removal only 3_2_1_m -> 3_2_m
3954 //
3955 class TransferNativeFunctionRegistration {
3956 private:
3957 InstanceKlass* the_class;
3958 int prefix_count;
3959 char** prefixes;
3960
3961 // Recursively search the binary tree of possibly prefixed method names.
3962 // Iteration could be used if all agents were well behaved. Full tree walk is
3963 // more resilent to agents not cleaning up intermediate methods.
3964 // Branch at each depth in the binary tree is:
3965 // (1) without the prefix.
3966 // (2) with the prefix.
3967 // where 'prefix' is the prefix at that 'depth' (first prefix, second prefix,...)
3968 Method* search_prefix_name_space(int depth, char* name_str, size_t name_len,
3969 Symbol* signature) {
3970 TempNewSymbol name_symbol = SymbolTable::probe(name_str, (int)name_len);
3971 if (name_symbol != nullptr) {
3972 Method* method = the_class->lookup_method(name_symbol, signature);
3973 if (method != nullptr) {
3974 // Even if prefixed, intermediate methods must exist.
3975 if (method->is_native()) {
3976 // Wahoo, we found a (possibly prefixed) version of the method, return it.
3977 return method;
3978 }
3979 if (depth < prefix_count) {
3980 // Try applying further prefixes (other than this one).
3981 method = search_prefix_name_space(depth+1, name_str, name_len, signature);
3982 if (method != nullptr) {
3983 return method; // found
3984 }
3985
3986 // Try adding this prefix to the method name and see if it matches
3987 // another method name.
3988 char* prefix = prefixes[depth];
3989 size_t prefix_len = strlen(prefix);
3990 size_t trial_len = name_len + prefix_len;
3991 char* trial_name_str = NEW_RESOURCE_ARRAY(char, trial_len + 1);
3992 strcpy(trial_name_str, prefix);
3993 strcat(trial_name_str, name_str);
3994 method = search_prefix_name_space(depth+1, trial_name_str, trial_len,
3995 signature);
3996 if (method != nullptr) {
3997 // If found along this branch, it was prefixed, mark as such
3998 method->set_is_prefixed_native();
3999 return method; // found
4000 }
4001 }
4002 }
4003 }
4004 return nullptr; // This whole branch bore nothing
4005 }
4006
4007 // Return the method name with old prefixes stripped away.
4008 char* method_name_without_prefixes(Method* method) {
4009 Symbol* name = method->name();
4010 char* name_str = name->as_utf8();
4011
4012 // Old prefixing may be defunct, strip prefixes, if any.
4013 for (int i = prefix_count-1; i >= 0; i--) {
4014 char* prefix = prefixes[i];
4015 size_t prefix_len = strlen(prefix);
4016 if (strncmp(prefix, name_str, prefix_len) == 0) {
4017 name_str += prefix_len;
4018 }
4019 }
4020 return name_str;
4021 }
4022
4023 // Strip any prefixes off the old native method, then try to find a
4024 // (possibly prefixed) new native that matches it.
4025 Method* strip_and_search_for_new_native(Method* method) {
4026 ResourceMark rm;
4027 char* name_str = method_name_without_prefixes(method);
4028 return search_prefix_name_space(0, name_str, strlen(name_str),
4029 method->signature());
4030 }
4031
4032 public:
4033
4034 // Construct a native method transfer processor for this class.
4035 TransferNativeFunctionRegistration(InstanceKlass* _the_class) {
4036 assert(SafepointSynchronize::is_at_safepoint(), "sanity check");
4037
4038 the_class = _the_class;
4039 prefixes = JvmtiExport::get_all_native_method_prefixes(&prefix_count);
4040 }
4041
4042 // Attempt to transfer any of the old or deleted methods that are native
4043 void transfer_registrations(Method** old_methods, int methods_length) {
4044 for (int j = 0; j < methods_length; j++) {
4045 Method* old_method = old_methods[j];
4046
4047 if (old_method->is_native() && old_method->has_native_function()) {
4048 Method* new_method = strip_and_search_for_new_native(old_method);
4049 if (new_method != nullptr) {
4050 // Actually set the native function in the new method.
4051 // Redefine does not send events (except CFLH), certainly not this
4052 // behind the scenes re-registration.
4053 new_method->set_native_function(old_method->native_function(),
4054 !Method::native_bind_event_is_interesting);
4055 }
4056 }
4057 }
4058 }
4059 };
4060
4061 // Don't lose the association between a native method and its JNI function.
4062 void VM_RedefineClasses::transfer_old_native_function_registrations(InstanceKlass* the_class) {
4063 TransferNativeFunctionRegistration transfer(the_class);
4064 transfer.transfer_registrations(_deleted_methods, _deleted_methods_length);
4065 transfer.transfer_registrations(_matching_old_methods, _matching_methods_length);
4066 }
4067
4068 // Deoptimize all compiled code that depends on the classes redefined.
4069 //
4070 // If the can_redefine_classes capability is obtained in the onload
4071 // phase or 'AlwaysRecordEvolDependencies' is true, then the compiler has
4072 // recorded all dependencies from startup. In that case we need only
4073 // deoptimize and throw away all compiled code that depends on the class.
4074 //
4075 // If can_redefine_classes is obtained sometime after the onload phase
4076 // (and 'AlwaysRecordEvolDependencies' is false) then the dependency
4077 // information may be incomplete. In that case the first call to
4078 // RedefineClasses causes all compiled code to be thrown away. As
4079 // can_redefine_classes has been obtained then all future compilations will
4080 // record dependencies so second and subsequent calls to RedefineClasses
4081 // need only throw away code that depends on the class.
4082 //
4083
4084 void VM_RedefineClasses::flush_dependent_code() {
4085 assert(SafepointSynchronize::is_at_safepoint(), "sanity check");
4086 assert(JvmtiExport::all_dependencies_are_recorded() || !AlwaysRecordEvolDependencies, "sanity check");
4087
4088 DeoptimizationScope deopt_scope;
4089
4090 // This is the first redefinition, mark all the nmethods for deoptimization
4091 if (!JvmtiExport::all_dependencies_are_recorded()) {
4092 CodeCache::mark_all_nmethods_for_evol_deoptimization(&deopt_scope);
4093 log_debug(redefine, class, nmethod)("Marked all nmethods for deopt");
4094 } else {
4095 CodeCache::mark_dependents_for_evol_deoptimization(&deopt_scope);
4096 log_debug(redefine, class, nmethod)("Marked dependent nmethods for deopt");
4097 }
4098
4099 deopt_scope.deoptimize_marked();
4100
4101 // From now on we know that the dependency information is complete
4102 JvmtiExport::set_all_dependencies_are_recorded(true);
4103 }
4104
4105 void VM_RedefineClasses::compute_added_deleted_matching_methods() {
4106 Method* old_method;
4107 Method* new_method;
4108
4109 _matching_old_methods = NEW_RESOURCE_ARRAY(Method*, _old_methods->length());
4110 _matching_new_methods = NEW_RESOURCE_ARRAY(Method*, _old_methods->length());
4111 _added_methods = NEW_RESOURCE_ARRAY(Method*, _new_methods->length());
4112 _deleted_methods = NEW_RESOURCE_ARRAY(Method*, _old_methods->length());
4113
4114 _matching_methods_length = 0;
4115 _deleted_methods_length = 0;
4116 _added_methods_length = 0;
4117
4118 int nj = 0;
4119 int oj = 0;
4120 while (true) {
4121 if (oj >= _old_methods->length()) {
4122 if (nj >= _new_methods->length()) {
4123 break; // we've looked at everything, done
4124 }
4125 // New method at the end
4126 new_method = _new_methods->at(nj);
4127 _added_methods[_added_methods_length++] = new_method;
4128 ++nj;
4129 } else if (nj >= _new_methods->length()) {
4130 // Old method, at the end, is deleted
4131 old_method = _old_methods->at(oj);
4132 _deleted_methods[_deleted_methods_length++] = old_method;
4133 ++oj;
4134 } else {
4135 old_method = _old_methods->at(oj);
4136 new_method = _new_methods->at(nj);
4137 if (old_method->name() == new_method->name()) {
4138 if (old_method->signature() == new_method->signature()) {
4139 _matching_old_methods[_matching_methods_length ] = old_method;
4140 _matching_new_methods[_matching_methods_length++] = new_method;
4141 ++nj;
4142 ++oj;
4143 } else {
4144 // added overloaded have already been moved to the end,
4145 // so this is a deleted overloaded method
4146 _deleted_methods[_deleted_methods_length++] = old_method;
4147 ++oj;
4148 }
4149 } else { // names don't match
4150 if (old_method->name()->fast_compare(new_method->name()) > 0) {
4151 // new method
4152 _added_methods[_added_methods_length++] = new_method;
4153 ++nj;
4154 } else {
4155 // deleted method
4156 _deleted_methods[_deleted_methods_length++] = old_method;
4157 ++oj;
4158 }
4159 }
4160 }
4161 }
4162 assert(_matching_methods_length + _deleted_methods_length == _old_methods->length(), "sanity");
4163 assert(_matching_methods_length + _added_methods_length == _new_methods->length(), "sanity");
4164 }
4165
4166
4167 void VM_RedefineClasses::swap_annotations(InstanceKlass* the_class,
4168 InstanceKlass* scratch_class) {
4169 // Swap annotation fields values
4170 Annotations* old_annotations = the_class->annotations();
4171 the_class->set_annotations(scratch_class->annotations());
4172 scratch_class->set_annotations(old_annotations);
4173 }
4174
4175
4176 // Install the redefinition of a class:
4177 // - house keeping (flushing breakpoints and caches, deoptimizing
4178 // dependent compiled code)
4179 // - replacing parts in the_class with parts from scratch_class
4180 // - adding a weak reference to track the obsolete but interesting
4181 // parts of the_class
4182 // - adjusting constant pool caches and vtables in other classes
4183 // that refer to methods in the_class. These adjustments use the
4184 // ClassLoaderDataGraph::classes_do() facility which only allows
4185 // a helper method to be specified. The interesting parameters
4186 // that we would like to pass to the helper method are saved in
4187 // static global fields in the VM operation.
4188 void VM_RedefineClasses::redefine_single_class(Thread* current, jclass the_jclass,
4189 InstanceKlass* scratch_class) {
4190
4191 HandleMark hm(current); // make sure handles from this call are freed
4192
4193 if (log_is_enabled(Info, redefine, class, timer)) {
4194 _timer_rsc_phase1.start();
4195 }
4196
4197 InstanceKlass* the_class = get_ik(the_jclass);
4198
4199 // Set a flag to control and optimize adjusting method entries
4200 _has_redefined_Object |= the_class == vmClasses::Object_klass();
4201
4202 // Remove all breakpoints in methods of this class
4203 JvmtiBreakpoints& jvmti_breakpoints = JvmtiCurrentBreakpoints::get_jvmti_breakpoints();
4204 jvmti_breakpoints.clearall_in_class_at_safepoint(the_class);
4205
4206 _old_methods = the_class->methods();
4207 _new_methods = scratch_class->methods();
4208 _the_class = the_class;
4209 compute_added_deleted_matching_methods();
4210 update_jmethod_ids();
4211
4212 _any_class_has_resolved_methods = the_class->has_resolved_methods() || _any_class_has_resolved_methods;
4213
4214 // Attach new constant pool to the original klass. The original
4215 // klass still refers to the old constant pool (for now).
4216 scratch_class->constants()->set_pool_holder(the_class);
4217
4218 #if 0
4219 // In theory, with constant pool merging in place we should be able
4220 // to save space by using the new, merged constant pool in place of
4221 // the old constant pool(s). By "pool(s)" I mean the constant pool in
4222 // the klass version we are replacing now and any constant pool(s) in
4223 // previous versions of klass. Nice theory, doesn't work in practice.
4224 // When this code is enabled, even simple programs throw NullPointer
4225 // exceptions. I'm guessing that this is caused by some constant pool
4226 // cache difference between the new, merged constant pool and the
4227 // constant pool that was just being used by the klass. I'm keeping
4228 // this code around to archive the idea, but the code has to remain
4229 // disabled for now.
4230
4231 // Attach each old method to the new constant pool. This can be
4232 // done here since we are past the bytecode verification and
4233 // constant pool optimization phases.
4234 for (int i = _old_methods->length() - 1; i >= 0; i--) {
4235 Method* method = _old_methods->at(i);
4236 method->set_constants(scratch_class->constants());
4237 }
4238
4239 // NOTE: this doesn't work because you can redefine the same class in two
4240 // threads, each getting their own constant pool data appended to the
4241 // original constant pool. In order for the new methods to work when they
4242 // become old methods, they need to keep their updated copy of the constant pool.
4243
4244 {
4245 // walk all previous versions of the klass
4246 InstanceKlass *ik = the_class;
4247 PreviousVersionWalker pvw(ik);
4248 do {
4249 ik = pvw.next_previous_version();
4250 if (ik != nullptr) {
4251
4252 // attach previous version of klass to the new constant pool
4253 ik->set_constants(scratch_class->constants());
4254
4255 // Attach each method in the previous version of klass to the
4256 // new constant pool
4257 Array<Method*>* prev_methods = ik->methods();
4258 for (int i = prev_methods->length() - 1; i >= 0; i--) {
4259 Method* method = prev_methods->at(i);
4260 method->set_constants(scratch_class->constants());
4261 }
4262 }
4263 } while (ik != nullptr);
4264 }
4265 #endif
4266
4267 // Replace methods and constantpool
4268 the_class->set_methods(_new_methods);
4269 scratch_class->set_methods(_old_methods); // To prevent potential GCing of the old methods,
4270 // and to be able to undo operation easily.
4271
4272 Array<int>* old_ordering = the_class->method_ordering();
4273 the_class->set_method_ordering(scratch_class->method_ordering());
4274 scratch_class->set_method_ordering(old_ordering);
4275
4276 ConstantPool* old_constants = the_class->constants();
4277 the_class->set_constants(scratch_class->constants());
4278 scratch_class->set_constants(old_constants); // See the previous comment.
4279 #if 0
4280 // We are swapping the guts of "the new class" with the guts of "the
4281 // class". Since the old constant pool has just been attached to "the
4282 // new class", it seems logical to set the pool holder in the old
4283 // constant pool also. However, doing this will change the observable
4284 // class hierarchy for any old methods that are still executing. A
4285 // method can query the identity of its "holder" and this query uses
4286 // the method's constant pool link to find the holder. The change in
4287 // holding class from "the class" to "the new class" can confuse
4288 // things.
4289 //
4290 // Setting the old constant pool's holder will also cause
4291 // verification done during vtable initialization below to fail.
4292 // During vtable initialization, the vtable's class is verified to be
4293 // a subtype of the method's holder. The vtable's class is "the
4294 // class" and the method's holder is gotten from the constant pool
4295 // link in the method itself. For "the class"'s directly implemented
4296 // methods, the method holder is "the class" itself (as gotten from
4297 // the new constant pool). The check works fine in this case. The
4298 // check also works fine for methods inherited from super classes.
4299 //
4300 // Miranda methods are a little more complicated. A miranda method is
4301 // provided by an interface when the class implementing the interface
4302 // does not provide its own method. These interfaces are implemented
4303 // internally as an InstanceKlass. These special instanceKlasses
4304 // share the constant pool of the class that "implements" the
4305 // interface. By sharing the constant pool, the method holder of a
4306 // miranda method is the class that "implements" the interface. In a
4307 // non-redefine situation, the subtype check works fine. However, if
4308 // the old constant pool's pool holder is modified, then the check
4309 // fails because there is no class hierarchy relationship between the
4310 // vtable's class and "the new class".
4311
4312 old_constants->set_pool_holder(scratch_class());
4313 #endif
4314
4315 // track number of methods that are EMCP for add_previous_version() call below
4316 int emcp_method_count = check_methods_and_mark_as_obsolete();
4317 transfer_old_native_function_registrations(the_class);
4318
4319 if (scratch_class->get_cached_class_file() != the_class->get_cached_class_file()) {
4320 // 1. the_class doesn't have a cache yet, scratch_class does have a cache.
4321 // 2. The same class can be present twice in the scratch classes list or there
4322 // are multiple concurrent RetransformClasses calls on different threads.
4323 // the_class and scratch_class have the same cached bytes, but different buffers.
4324 // In such cases we need to deallocate one of the buffers.
4325 // 3. RedefineClasses and the_class has cached bytes from a previous transformation.
4326 // In the case we need to use class bytes from scratch_class.
4327 if (the_class->get_cached_class_file() != nullptr) {
4328 os::free(the_class->get_cached_class_file());
4329 }
4330 the_class->set_cached_class_file(scratch_class->get_cached_class_file());
4331 }
4332
4333 // null out in scratch class to not delete twice. The class to be redefined
4334 // always owns these bytes.
4335 scratch_class->set_cached_class_file(nullptr);
4336
4337 // Replace inner_classes
4338 Array<u2>* old_inner_classes = the_class->inner_classes();
4339 the_class->set_inner_classes(scratch_class->inner_classes());
4340 scratch_class->set_inner_classes(old_inner_classes);
4341
4342 // Initialize the vtable and interface table after
4343 // methods have been rewritten
4344 // no exception should happen here since we explicitly
4345 // do not check loader constraints.
4346 // compare_and_normalize_class_versions has already checked:
4347 // - classloaders unchanged, signatures unchanged
4348 // - all instanceKlasses for redefined classes reused & contents updated
4349 the_class->vtable().initialize_vtable();
4350 the_class->itable().initialize_itable();
4351
4352 // Update jmethodID cache if present.
4353 the_class->update_methods_jmethod_cache();
4354
4355 // Copy the "source debug extension" attribute from new class version
4356 the_class->set_source_debug_extension(
4357 scratch_class->source_debug_extension(),
4358 scratch_class->source_debug_extension() == nullptr ? 0 :
4359 (int)strlen(scratch_class->source_debug_extension()));
4360
4361 // Use of javac -g could be different in the old and the new
4362 if (scratch_class->has_localvariable_table() !=
4363 the_class->has_localvariable_table()) {
4364 the_class->set_has_localvariable_table(scratch_class->has_localvariable_table());
4365 }
4366
4367 swap_annotations(the_class, scratch_class);
4368
4369 // Replace minor version number of class file
4370 u2 old_minor_version = the_class->constants()->minor_version();
4371 the_class->constants()->set_minor_version(scratch_class->constants()->minor_version());
4372 scratch_class->constants()->set_minor_version(old_minor_version);
4373
4374 // Replace major version number of class file
4375 u2 old_major_version = the_class->constants()->major_version();
4376 the_class->constants()->set_major_version(scratch_class->constants()->major_version());
4377 scratch_class->constants()->set_major_version(old_major_version);
4378
4379 // Replace CP indexes for class and name+type of enclosing method
4380 u2 old_class_idx = the_class->enclosing_method_class_index();
4381 u2 old_method_idx = the_class->enclosing_method_method_index();
4382 the_class->set_enclosing_method_indices(
4383 scratch_class->enclosing_method_class_index(),
4384 scratch_class->enclosing_method_method_index());
4385 scratch_class->set_enclosing_method_indices(old_class_idx, old_method_idx);
4386
4387 if (!the_class->has_been_redefined()) {
4388 the_class->set_has_been_redefined();
4389 }
4390
4391 // Scratch class is unloaded but still needs cleaning, and skipping for CDS.
4392 scratch_class->set_is_scratch_class();
4393
4394 // keep track of previous versions of this class
4395 the_class->add_previous_version(scratch_class, emcp_method_count);
4396
4397 _timer_rsc_phase1.stop();
4398 if (log_is_enabled(Info, redefine, class, timer)) {
4399 _timer_rsc_phase2.start();
4400 }
4401
4402 if (the_class->oop_map_cache() != nullptr) {
4403 // Flush references to any obsolete methods from the oop map cache
4404 // so that obsolete methods are not pinned.
4405 the_class->oop_map_cache()->flush_obsolete_entries();
4406 }
4407
4408 increment_class_counter(the_class);
4409
4410 if (EventClassRedefinition::is_enabled()) {
4411 EventClassRedefinition event;
4412 event.set_classModificationCount(java_lang_Class::classRedefinedCount(the_class->java_mirror()));
4413 event.set_redefinedClass(the_class);
4414 event.set_redefinitionId(_id);
4415 event.commit();
4416 }
4417
4418 {
4419 ResourceMark rm(current);
4420 // increment the classRedefinedCount field in the_class and in any
4421 // direct and indirect subclasses of the_class
4422 log_info(redefine, class, load)
4423 ("redefined name=%s, count=%d (avail_mem=" UINT64_FORMAT "K)",
4424 the_class->external_name(), java_lang_Class::classRedefinedCount(the_class->java_mirror()), os::available_memory() >> 10);
4425 Events::log_redefinition(current, "redefined class name=%s, count=%d",
4426 the_class->external_name(),
4427 java_lang_Class::classRedefinedCount(the_class->java_mirror()));
4428
4429 }
4430 _timer_rsc_phase2.stop();
4431
4432 } // end redefine_single_class()
4433
4434
4435 // Increment the classRedefinedCount field in the specific InstanceKlass
4436 // and in all direct and indirect subclasses.
4437 void VM_RedefineClasses::increment_class_counter(InstanceKlass* ik) {
4438 for (ClassHierarchyIterator iter(ik); !iter.done(); iter.next()) {
4439 // Only update instanceKlasses
4440 Klass* sub = iter.klass();
4441 if (sub->is_instance_klass()) {
4442 oop class_mirror = InstanceKlass::cast(sub)->java_mirror();
4443 Klass* class_oop = java_lang_Class::as_Klass(class_mirror);
4444 int new_count = java_lang_Class::classRedefinedCount(class_mirror) + 1;
4445 java_lang_Class::set_classRedefinedCount(class_mirror, new_count);
4446
4447 if (class_oop != _the_class) {
4448 // _the_class count is printed at end of redefine_single_class()
4449 log_debug(redefine, class, subclass)("updated count in subclass=%s to %d", ik->external_name(), new_count);
4450 }
4451 }
4452 }
4453 }
4454
4455 void VM_RedefineClasses::CheckClass::do_klass(Klass* k) {
4456 bool no_old_methods = true; // be optimistic
4457
4458 // Both array and instance classes have vtables.
4459 // a vtable should never contain old or obsolete methods
4460 ResourceMark rm(_thread);
4461 if (k->vtable_length() > 0 &&
4462 !k->vtable().check_no_old_or_obsolete_entries()) {
4463 if (log_is_enabled(Trace, redefine, class, obsolete, metadata)) {
4464 log_trace(redefine, class, obsolete, metadata)
4465 ("klassVtable::check_no_old_or_obsolete_entries failure -- OLD or OBSOLETE method found -- class: %s",
4466 k->signature_name());
4467 k->vtable().dump_vtable();
4468 }
4469 no_old_methods = false;
4470 }
4471
4472 if (k->is_instance_klass()) {
4473 HandleMark hm(_thread);
4474 InstanceKlass *ik = InstanceKlass::cast(k);
4475
4476 // an itable should never contain old or obsolete methods
4477 if (ik->itable_length() > 0 &&
4478 !ik->itable().check_no_old_or_obsolete_entries()) {
4479 if (log_is_enabled(Trace, redefine, class, obsolete, metadata)) {
4480 log_trace(redefine, class, obsolete, metadata)
4481 ("klassItable::check_no_old_or_obsolete_entries failure -- OLD or OBSOLETE method found -- class: %s",
4482 ik->signature_name());
4483 ik->itable().dump_itable();
4484 }
4485 no_old_methods = false;
4486 }
4487
4488 // the constant pool cache should never contain non-deleted old or obsolete methods
4489 if (ik->constants() != nullptr &&
4490 ik->constants()->cache() != nullptr &&
4491 !ik->constants()->cache()->check_no_old_or_obsolete_entries()) {
4492 if (log_is_enabled(Trace, redefine, class, obsolete, metadata)) {
4493 log_trace(redefine, class, obsolete, metadata)
4494 ("cp-cache::check_no_old_or_obsolete_entries failure -- OLD or OBSOLETE method found -- class: %s",
4495 ik->signature_name());
4496 ik->constants()->cache()->dump_cache();
4497 }
4498 no_old_methods = false;
4499 }
4500 }
4501
4502 // print and fail guarantee if old methods are found.
4503 if (!no_old_methods) {
4504 if (log_is_enabled(Trace, redefine, class, obsolete, metadata)) {
4505 dump_methods();
4506 } else {
4507 log_trace(redefine, class)("Use the '-Xlog:redefine+class*:' option "
4508 "to see more info about the following guarantee() failure.");
4509 }
4510 guarantee(false, "OLD and/or OBSOLETE method(s) found");
4511 }
4512 }
4513
4514 u8 VM_RedefineClasses::next_id() {
4515 while (true) {
4516 u8 id = _id_counter;
4517 u8 next_id = id + 1;
4518 u8 result = Atomic::cmpxchg(&_id_counter, id, next_id);
4519 if (result == id) {
4520 return next_id;
4521 }
4522 }
4523 }
4524
4525 void VM_RedefineClasses::dump_methods() {
4526 int j;
4527 log_trace(redefine, class, dump)("_old_methods --");
4528 for (j = 0; j < _old_methods->length(); ++j) {
4529 LogStreamHandle(Trace, redefine, class, dump) log_stream;
4530 Method* m = _old_methods->at(j);
4531 log_stream.print("%4d (%5d) ", j, m->vtable_index());
4532 m->access_flags().print_on(&log_stream);
4533 log_stream.print(" -- ");
4534 m->print_name(&log_stream);
4535 log_stream.cr();
4536 }
4537 log_trace(redefine, class, dump)("_new_methods --");
4538 for (j = 0; j < _new_methods->length(); ++j) {
4539 LogStreamHandle(Trace, redefine, class, dump) log_stream;
4540 Method* m = _new_methods->at(j);
4541 log_stream.print("%4d (%5d) ", j, m->vtable_index());
4542 m->access_flags().print_on(&log_stream);
4543 log_stream.print(" -- ");
4544 m->print_name(&log_stream);
4545 log_stream.cr();
4546 }
4547 log_trace(redefine, class, dump)("_matching_methods --");
4548 for (j = 0; j < _matching_methods_length; ++j) {
4549 LogStreamHandle(Trace, redefine, class, dump) log_stream;
4550 Method* m = _matching_old_methods[j];
4551 log_stream.print("%4d (%5d) ", j, m->vtable_index());
4552 m->access_flags().print_on(&log_stream);
4553 log_stream.print(" -- ");
4554 m->print_name();
4555 log_stream.cr();
4556
4557 m = _matching_new_methods[j];
4558 log_stream.print(" (%5d) ", m->vtable_index());
4559 m->access_flags().print_on(&log_stream);
4560 log_stream.cr();
4561 }
4562 log_trace(redefine, class, dump)("_deleted_methods --");
4563 for (j = 0; j < _deleted_methods_length; ++j) {
4564 LogStreamHandle(Trace, redefine, class, dump) log_stream;
4565 Method* m = _deleted_methods[j];
4566 log_stream.print("%4d (%5d) ", j, m->vtable_index());
4567 m->access_flags().print_on(&log_stream);
4568 log_stream.print(" -- ");
4569 m->print_name(&log_stream);
4570 log_stream.cr();
4571 }
4572 log_trace(redefine, class, dump)("_added_methods --");
4573 for (j = 0; j < _added_methods_length; ++j) {
4574 LogStreamHandle(Trace, redefine, class, dump) log_stream;
4575 Method* m = _added_methods[j];
4576 log_stream.print("%4d (%5d) ", j, m->vtable_index());
4577 m->access_flags().print_on(&log_stream);
4578 log_stream.print(" -- ");
4579 m->print_name(&log_stream);
4580 log_stream.cr();
4581 }
4582 }
4583
4584 void VM_RedefineClasses::print_on_error(outputStream* st) const {
4585 VM_Operation::print_on_error(st);
4586 if (_the_class != nullptr) {
4587 ResourceMark rm;
4588 st->print_cr(", redefining class %s", _the_class->external_name());
4589 }
4590 }