1 /*
2 * Copyright (c) 2003, 2021, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
24
25 #include "precompiled.hpp"
26 #include "cds/metaspaceShared.hpp"
27 #include "classfile/classFileStream.hpp"
28 #include "classfile/classLoaderDataGraph.hpp"
29 #include "classfile/classLoadInfo.hpp"
30 #include "classfile/javaClasses.inline.hpp"
31 #include "classfile/metadataOnStackMark.hpp"
32 #include "classfile/symbolTable.hpp"
33 #include "classfile/klassFactory.hpp"
34 #include "classfile/verifier.hpp"
35 #include "classfile/vmClasses.hpp"
36 #include "classfile/vmSymbols.hpp"
37 #include "code/codeCache.hpp"
38 #include "compiler/compileBroker.hpp"
39 #include "interpreter/oopMapCache.hpp"
40 #include "interpreter/rewriter.hpp"
41 #include "jfr/jfrEvents.hpp"
42 #include "logging/logStream.hpp"
43 #include "memory/metadataFactory.hpp"
44 #include "memory/resourceArea.hpp"
45 #include "memory/universe.hpp"
46 #include "oops/annotations.hpp"
47 #include "oops/constantPool.hpp"
48 #include "oops/fieldStreams.inline.hpp"
49 #include "oops/klass.inline.hpp"
50 #include "oops/klassVtable.hpp"
51 #include "oops/oop.inline.hpp"
52 #include "oops/recordComponent.hpp"
53 #include "prims/jvmtiImpl.hpp"
54 #include "prims/jvmtiRedefineClasses.hpp"
55 #include "prims/jvmtiThreadState.inline.hpp"
56 #include "prims/resolvedMethodTable.hpp"
57 #include "prims/methodComparator.hpp"
58 #include "runtime/atomic.hpp"
59 #include "runtime/deoptimization.hpp"
60 #include "runtime/handles.inline.hpp"
61 #include "runtime/jniHandles.inline.hpp"
62 #include "runtime/relocator.hpp"
63 #include "runtime/safepointVerifiers.hpp"
64 #include "utilities/bitMap.inline.hpp"
65 #include "utilities/events.hpp"
66
67 Array<Method*>* VM_RedefineClasses::_old_methods = NULL;
68 Array<Method*>* VM_RedefineClasses::_new_methods = NULL;
69 Method** VM_RedefineClasses::_matching_old_methods = NULL;
70 Method** VM_RedefineClasses::_matching_new_methods = NULL;
71 Method** VM_RedefineClasses::_deleted_methods = NULL;
72 Method** VM_RedefineClasses::_added_methods = NULL;
73 int VM_RedefineClasses::_matching_methods_length = 0;
74 int VM_RedefineClasses::_deleted_methods_length = 0;
75 int VM_RedefineClasses::_added_methods_length = 0;
76
77 // This flag is global as the constructor does not reset it:
78 bool VM_RedefineClasses::_has_redefined_Object = false;
79 u8 VM_RedefineClasses::_id_counter = 0;
80
81 VM_RedefineClasses::VM_RedefineClasses(jint class_count,
82 const jvmtiClassDefinition *class_defs,
83 JvmtiClassLoadKind class_load_kind) {
84 _class_count = class_count;
85 _class_defs = class_defs;
86 _class_load_kind = class_load_kind;
87 _any_class_has_resolved_methods = false;
88 _res = JVMTI_ERROR_NONE;
89 _the_class = NULL;
90 _id = next_id();
91 }
92
93 static inline InstanceKlass* get_ik(jclass def) {
94 oop mirror = JNIHandles::resolve_non_null(def);
95 return InstanceKlass::cast(java_lang_Class::as_Klass(mirror));
96 }
97
98 // If any of the classes are being redefined, wait
99 // Parallel constant pool merging leads to indeterminate constant pools.
100 void VM_RedefineClasses::lock_classes() {
101 JvmtiThreadState *state = JvmtiThreadState::state_for(JavaThread::current());
102 GrowableArray<Klass*>* redef_classes = state->get_classes_being_redefined();
103
104 MonitorLocker ml(RedefineClasses_lock);
105
106 if (redef_classes == NULL) {
107 redef_classes = new(ResourceObj::C_HEAP, mtClass) GrowableArray<Klass*>(1, mtClass);
108 state->set_classes_being_redefined(redef_classes);
109 }
110
111 bool has_redefined;
112 do {
113 has_redefined = false;
114 // Go through classes each time until none are being redefined. Skip
115 // the ones that are being redefined by this thread currently. Class file
116 // load hook event may trigger new class redefine when we are redefining
117 // a class (after lock_classes()).
118 for (int i = 0; i < _class_count; i++) {
119 InstanceKlass* ik = get_ik(_class_defs[i].klass);
120 // Check if we are currently redefining the class in this thread already.
121 if (redef_classes->contains(ik)) {
122 assert(ik->is_being_redefined(), "sanity");
123 } else {
124 if (ik->is_being_redefined()) {
125 ml.wait();
126 has_redefined = true;
127 break; // for loop
128 }
129 }
130 }
131 } while (has_redefined);
132
133 for (int i = 0; i < _class_count; i++) {
134 InstanceKlass* ik = get_ik(_class_defs[i].klass);
135 redef_classes->push(ik); // Add to the _classes_being_redefined list
136 ik->set_is_being_redefined(true);
137 }
138 ml.notify_all();
139 }
140
141 void VM_RedefineClasses::unlock_classes() {
142 JvmtiThreadState *state = JvmtiThreadState::state_for(JavaThread::current());
143 GrowableArray<Klass*>* redef_classes = state->get_classes_being_redefined();
144 assert(redef_classes != NULL, "_classes_being_redefined is not allocated");
145
146 MonitorLocker ml(RedefineClasses_lock);
147
148 for (int i = _class_count - 1; i >= 0; i--) {
149 InstanceKlass* def_ik = get_ik(_class_defs[i].klass);
150 if (redef_classes->length() > 0) {
151 // Remove the class from _classes_being_redefined list
152 Klass* k = redef_classes->pop();
153 assert(def_ik == k, "unlocking wrong class");
154 }
155 assert(def_ik->is_being_redefined(),
156 "should be being redefined to get here");
157
158 // Unlock after we finish all redefines for this class within
159 // the thread. Same class can be pushed to the list multiple
160 // times (not more than once by each recursive redefinition).
161 if (!redef_classes->contains(def_ik)) {
162 def_ik->set_is_being_redefined(false);
163 }
164 }
165 ml.notify_all();
166 }
167
168 bool VM_RedefineClasses::doit_prologue() {
169 if (_class_count == 0) {
170 _res = JVMTI_ERROR_NONE;
171 return false;
172 }
173 if (_class_defs == NULL) {
174 _res = JVMTI_ERROR_NULL_POINTER;
175 return false;
176 }
177
178 for (int i = 0; i < _class_count; i++) {
179 if (_class_defs[i].klass == NULL) {
180 _res = JVMTI_ERROR_INVALID_CLASS;
181 return false;
182 }
183 if (_class_defs[i].class_byte_count == 0) {
184 _res = JVMTI_ERROR_INVALID_CLASS_FORMAT;
185 return false;
186 }
187 if (_class_defs[i].class_bytes == NULL) {
188 _res = JVMTI_ERROR_NULL_POINTER;
189 return false;
190 }
191
192 oop mirror = JNIHandles::resolve_non_null(_class_defs[i].klass);
193 // classes for primitives, arrays, and hidden classes
194 // cannot be redefined.
195 if (!is_modifiable_class(mirror)) {
196 _res = JVMTI_ERROR_UNMODIFIABLE_CLASS;
197 return false;
198 }
199 }
200
201 // Start timer after all the sanity checks; not quite accurate, but
202 // better than adding a bunch of stop() calls.
203 if (log_is_enabled(Info, redefine, class, timer)) {
204 _timer_vm_op_prologue.start();
205 }
206
207 lock_classes();
208 // We first load new class versions in the prologue, because somewhere down the
209 // call chain it is required that the current thread is a Java thread.
210 _res = load_new_class_versions();
211 if (_res != JVMTI_ERROR_NONE) {
212 // free any successfully created classes, since none are redefined
213 for (int i = 0; i < _class_count; i++) {
214 if (_scratch_classes[i] != NULL) {
215 ClassLoaderData* cld = _scratch_classes[i]->class_loader_data();
216 // Free the memory for this class at class unloading time. Not before
217 // because CMS might think this is still live.
218 InstanceKlass* ik = get_ik(_class_defs[i].klass);
219 if (ik->get_cached_class_file() == _scratch_classes[i]->get_cached_class_file()) {
220 // Don't double-free cached_class_file copied from the original class if error.
221 _scratch_classes[i]->set_cached_class_file(NULL);
222 }
223 cld->add_to_deallocate_list(InstanceKlass::cast(_scratch_classes[i]));
224 }
225 }
226 // Free os::malloc allocated memory in load_new_class_version.
227 os::free(_scratch_classes);
228 _timer_vm_op_prologue.stop();
229 unlock_classes();
230 return false;
231 }
232
233 _timer_vm_op_prologue.stop();
234 return true;
235 }
236
237 void VM_RedefineClasses::doit() {
238 Thread* current = Thread::current();
239
240 #if INCLUDE_CDS
241 if (UseSharedSpaces) {
242 // Sharing is enabled so we remap the shared readonly space to
243 // shared readwrite, private just in case we need to redefine
244 // a shared class. We do the remap during the doit() phase of
245 // the safepoint to be safer.
246 if (!MetaspaceShared::remap_shared_readonly_as_readwrite()) {
247 log_info(redefine, class, load)("failed to remap shared readonly space to readwrite, private");
248 _res = JVMTI_ERROR_INTERNAL;
249 return;
250 }
251 }
252 #endif
253
254 // Mark methods seen on stack and everywhere else so old methods are not
255 // cleaned up if they're on the stack.
256 MetadataOnStackMark md_on_stack(/*walk_all_metadata*/true, /*redefinition_walk*/true);
257 HandleMark hm(current); // make sure any handles created are deleted
258 // before the stack walk again.
259
260 for (int i = 0; i < _class_count; i++) {
261 redefine_single_class(current, _class_defs[i].klass, _scratch_classes[i]);
262 }
263
264 // Flush all compiled code that depends on the classes redefined.
265 flush_dependent_code();
266
267 // Adjust constantpool caches and vtables for all classes
268 // that reference methods of the evolved classes.
269 // Have to do this after all classes are redefined and all methods that
270 // are redefined are marked as old.
271 AdjustAndCleanMetadata adjust_and_clean_metadata(current);
272 ClassLoaderDataGraph::classes_do(&adjust_and_clean_metadata);
273
274 // JSR-292 support
275 if (_any_class_has_resolved_methods) {
276 bool trace_name_printed = false;
277 ResolvedMethodTable::adjust_method_entries(&trace_name_printed);
278 }
279
280 // Increment flag indicating that some invariants are no longer true.
281 // See jvmtiExport.hpp for detailed explanation.
282 JvmtiExport::increment_redefinition_count();
283
284 // check_class() is optionally called for product bits, but is
285 // always called for non-product bits.
286 #ifdef PRODUCT
287 if (log_is_enabled(Trace, redefine, class, obsolete, metadata)) {
288 #endif
289 log_trace(redefine, class, obsolete, metadata)("calling check_class");
290 CheckClass check_class(current);
291 ClassLoaderDataGraph::classes_do(&check_class);
292 #ifdef PRODUCT
293 }
294 #endif
295
296 // Clean up any metadata now unreferenced while MetadataOnStackMark is set.
297 ClassLoaderDataGraph::clean_deallocate_lists(false);
298 }
299
300 void VM_RedefineClasses::doit_epilogue() {
301 unlock_classes();
302
303 // Free os::malloc allocated memory.
304 os::free(_scratch_classes);
305
306 // Reset the_class to null for error printing.
307 _the_class = NULL;
308
309 if (log_is_enabled(Info, redefine, class, timer)) {
310 // Used to have separate timers for "doit" and "all", but the timer
311 // overhead skewed the measurements.
312 julong doit_time = _timer_rsc_phase1.milliseconds() +
313 _timer_rsc_phase2.milliseconds();
314 julong all_time = _timer_vm_op_prologue.milliseconds() + doit_time;
315
316 log_info(redefine, class, timer)
317 ("vm_op: all=" JULONG_FORMAT " prologue=" JULONG_FORMAT " doit=" JULONG_FORMAT,
318 all_time, (julong)_timer_vm_op_prologue.milliseconds(), doit_time);
319 log_info(redefine, class, timer)
320 ("redefine_single_class: phase1=" JULONG_FORMAT " phase2=" JULONG_FORMAT,
321 (julong)_timer_rsc_phase1.milliseconds(), (julong)_timer_rsc_phase2.milliseconds());
322 }
323 }
324
325 bool VM_RedefineClasses::is_modifiable_class(oop klass_mirror) {
326 // classes for primitives cannot be redefined
327 if (java_lang_Class::is_primitive(klass_mirror)) {
328 return false;
329 }
330 Klass* k = java_lang_Class::as_Klass(klass_mirror);
331 // classes for arrays cannot be redefined
332 if (k == NULL || !k->is_instance_klass()) {
333 return false;
334 }
335
336 // Cannot redefine or retransform interface java.lang.IdentityObject.
337 if (k->name() == vmSymbols::java_lang_IdentityObject()) {
338 return false;
339 }
340 // Cannot redefine or retransform interface java.lang.PrimitiveObject.
341 if (k->name() == vmSymbols::java_lang_PrimitiveObject()) {
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 return true;
350 }
351
352 // Append the current entry at scratch_i in scratch_cp to *merge_cp_p
353 // where the end of *merge_cp_p is specified by *merge_cp_length_p. For
354 // direct CP entries, there is just the current entry to append. For
355 // indirect and double-indirect CP entries, there are zero or more
356 // referenced CP entries along with the current entry to append.
357 // Indirect and double-indirect CP entries are handled by recursive
358 // calls to append_entry() as needed. The referenced CP entries are
359 // always appended to *merge_cp_p before the referee CP entry. These
360 // referenced CP entries may already exist in *merge_cp_p in which case
361 // there is nothing extra to append and only the current entry is
362 // appended.
363 void VM_RedefineClasses::append_entry(const constantPoolHandle& scratch_cp,
364 int scratch_i, constantPoolHandle *merge_cp_p, int *merge_cp_length_p) {
365
366 // append is different depending on entry tag type
367 switch (scratch_cp->tag_at(scratch_i).value()) {
368
369 // The old verifier is implemented outside the VM. It loads classes,
370 // but does not resolve constant pool entries directly so we never
371 // see Class entries here with the old verifier. Similarly the old
372 // verifier does not like Class entries in the input constant pool.
373 // The split-verifier is implemented in the VM so it can optionally
374 // and directly resolve constant pool entries to load classes. The
375 // split-verifier can accept either Class entries or UnresolvedClass
376 // entries in the input constant pool. We revert the appended copy
377 // back to UnresolvedClass so that either verifier will be happy
378 // with the constant pool entry.
379 //
380 // this is an indirect CP entry so it needs special handling
381 case JVM_CONSTANT_Class:
382 case JVM_CONSTANT_UnresolvedClass:
383 {
384 int name_i = scratch_cp->klass_name_index_at(scratch_i);
385 int new_name_i = find_or_append_indirect_entry(scratch_cp, name_i, merge_cp_p,
386 merge_cp_length_p);
387
388 if (new_name_i != name_i) {
389 log_trace(redefine, class, constantpool)
390 ("Class entry@%d name_index change: %d to %d",
391 *merge_cp_length_p, name_i, new_name_i);
392 }
393
394 (*merge_cp_p)->temp_unresolved_klass_at_put(*merge_cp_length_p, new_name_i);
395 if (scratch_i != *merge_cp_length_p) {
396 // The new entry in *merge_cp_p is at a different index than
397 // the new entry in scratch_cp so we need to map the index values.
398 map_index(scratch_cp, scratch_i, *merge_cp_length_p);
399 }
400 (*merge_cp_length_p)++;
401 } break;
402
403 // these are direct CP entries so they can be directly appended,
404 // but double and long take two constant pool entries
405 case JVM_CONSTANT_Double: // fall through
406 case JVM_CONSTANT_Long:
407 {
408 ConstantPool::copy_entry_to(scratch_cp, scratch_i, *merge_cp_p, *merge_cp_length_p);
409
410 if (scratch_i != *merge_cp_length_p) {
411 // The new entry in *merge_cp_p is at a different index than
412 // the new entry in scratch_cp so we need to map the index values.
413 map_index(scratch_cp, scratch_i, *merge_cp_length_p);
414 }
415 (*merge_cp_length_p) += 2;
416 } break;
417
418 // these are direct CP entries so they can be directly appended
419 case JVM_CONSTANT_Float: // fall through
420 case JVM_CONSTANT_Integer: // fall through
421 case JVM_CONSTANT_Utf8: // fall through
422
423 // This was an indirect CP entry, but it has been changed into
424 // Symbol*s so this entry can be directly appended.
425 case JVM_CONSTANT_String: // fall through
426 {
427 ConstantPool::copy_entry_to(scratch_cp, scratch_i, *merge_cp_p, *merge_cp_length_p);
428
429 if (scratch_i != *merge_cp_length_p) {
430 // The new entry in *merge_cp_p is at a different index than
431 // the new entry in scratch_cp so we need to map the index values.
432 map_index(scratch_cp, scratch_i, *merge_cp_length_p);
433 }
434 (*merge_cp_length_p)++;
435 } break;
436
437 // this is an indirect CP entry so it needs special handling
438 case JVM_CONSTANT_NameAndType:
439 {
440 int name_ref_i = scratch_cp->name_ref_index_at(scratch_i);
441 int new_name_ref_i = find_or_append_indirect_entry(scratch_cp, name_ref_i, merge_cp_p,
442 merge_cp_length_p);
443
444 int signature_ref_i = scratch_cp->signature_ref_index_at(scratch_i);
445 int new_signature_ref_i = find_or_append_indirect_entry(scratch_cp, signature_ref_i,
446 merge_cp_p, merge_cp_length_p);
447
448 // If the referenced entries already exist in *merge_cp_p, then
449 // both new_name_ref_i and new_signature_ref_i will both be 0.
450 // In that case, all we are appending is the current entry.
451 if (new_name_ref_i != name_ref_i) {
452 log_trace(redefine, class, constantpool)
453 ("NameAndType entry@%d name_ref_index change: %d to %d",
454 *merge_cp_length_p, name_ref_i, new_name_ref_i);
455 }
456 if (new_signature_ref_i != signature_ref_i) {
457 log_trace(redefine, class, constantpool)
458 ("NameAndType entry@%d signature_ref_index change: %d to %d",
459 *merge_cp_length_p, signature_ref_i, new_signature_ref_i);
460 }
461
462 (*merge_cp_p)->name_and_type_at_put(*merge_cp_length_p,
463 new_name_ref_i, new_signature_ref_i);
464 if (scratch_i != *merge_cp_length_p) {
465 // The new entry in *merge_cp_p is at a different index than
466 // the new entry in scratch_cp so we need to map the index values.
467 map_index(scratch_cp, scratch_i, *merge_cp_length_p);
468 }
469 (*merge_cp_length_p)++;
470 } break;
471
472 // this is a double-indirect CP entry so it needs special handling
473 case JVM_CONSTANT_Fieldref: // fall through
474 case JVM_CONSTANT_InterfaceMethodref: // fall through
475 case JVM_CONSTANT_Methodref:
476 {
477 int klass_ref_i = scratch_cp->uncached_klass_ref_index_at(scratch_i);
478 int new_klass_ref_i = find_or_append_indirect_entry(scratch_cp, klass_ref_i,
479 merge_cp_p, merge_cp_length_p);
480
481 int name_and_type_ref_i = scratch_cp->uncached_name_and_type_ref_index_at(scratch_i);
482 int new_name_and_type_ref_i = find_or_append_indirect_entry(scratch_cp, name_and_type_ref_i,
483 merge_cp_p, merge_cp_length_p);
484
485 const char *entry_name = NULL;
486 switch (scratch_cp->tag_at(scratch_i).value()) {
487 case JVM_CONSTANT_Fieldref:
488 entry_name = "Fieldref";
489 (*merge_cp_p)->field_at_put(*merge_cp_length_p, new_klass_ref_i,
490 new_name_and_type_ref_i);
491 break;
492 case JVM_CONSTANT_InterfaceMethodref:
493 entry_name = "IFMethodref";
494 (*merge_cp_p)->interface_method_at_put(*merge_cp_length_p,
495 new_klass_ref_i, new_name_and_type_ref_i);
496 break;
497 case JVM_CONSTANT_Methodref:
498 entry_name = "Methodref";
499 (*merge_cp_p)->method_at_put(*merge_cp_length_p, new_klass_ref_i,
500 new_name_and_type_ref_i);
501 break;
502 default:
503 guarantee(false, "bad switch");
504 break;
505 }
506
507 if (klass_ref_i != new_klass_ref_i) {
508 log_trace(redefine, class, constantpool)
509 ("%s entry@%d class_index changed: %d to %d", entry_name, *merge_cp_length_p, klass_ref_i, new_klass_ref_i);
510 }
511 if (name_and_type_ref_i != new_name_and_type_ref_i) {
512 log_trace(redefine, class, constantpool)
513 ("%s entry@%d name_and_type_index changed: %d to %d",
514 entry_name, *merge_cp_length_p, name_and_type_ref_i, new_name_and_type_ref_i);
515 }
516
517 if (scratch_i != *merge_cp_length_p) {
518 // The new entry in *merge_cp_p is at a different index than
519 // the new entry in scratch_cp so we need to map the index values.
520 map_index(scratch_cp, scratch_i, *merge_cp_length_p);
521 }
522 (*merge_cp_length_p)++;
523 } break;
524
525 // this is an indirect CP entry so it needs special handling
526 case JVM_CONSTANT_MethodType:
527 {
528 int ref_i = scratch_cp->method_type_index_at(scratch_i);
529 int new_ref_i = find_or_append_indirect_entry(scratch_cp, ref_i, merge_cp_p,
530 merge_cp_length_p);
531 if (new_ref_i != ref_i) {
532 log_trace(redefine, class, constantpool)
533 ("MethodType entry@%d ref_index change: %d to %d", *merge_cp_length_p, ref_i, new_ref_i);
534 }
535 (*merge_cp_p)->method_type_index_at_put(*merge_cp_length_p, new_ref_i);
536 if (scratch_i != *merge_cp_length_p) {
537 // The new entry in *merge_cp_p is at a different index than
538 // the new entry in scratch_cp so we need to map the index values.
539 map_index(scratch_cp, scratch_i, *merge_cp_length_p);
540 }
541 (*merge_cp_length_p)++;
542 } break;
543
544 // this is an indirect CP entry so it needs special handling
545 case JVM_CONSTANT_MethodHandle:
546 {
547 int ref_kind = scratch_cp->method_handle_ref_kind_at(scratch_i);
548 int ref_i = scratch_cp->method_handle_index_at(scratch_i);
549 int new_ref_i = find_or_append_indirect_entry(scratch_cp, ref_i, merge_cp_p,
550 merge_cp_length_p);
551 if (new_ref_i != ref_i) {
552 log_trace(redefine, class, constantpool)
553 ("MethodHandle entry@%d ref_index change: %d to %d", *merge_cp_length_p, ref_i, new_ref_i);
554 }
555 (*merge_cp_p)->method_handle_index_at_put(*merge_cp_length_p, ref_kind, new_ref_i);
556 if (scratch_i != *merge_cp_length_p) {
557 // The new entry in *merge_cp_p is at a different index than
558 // the new entry in scratch_cp so we need to map the index values.
559 map_index(scratch_cp, scratch_i, *merge_cp_length_p);
560 }
561 (*merge_cp_length_p)++;
562 } break;
563
564 // this is an indirect CP entry so it needs special handling
565 case JVM_CONSTANT_Dynamic: // fall through
566 case JVM_CONSTANT_InvokeDynamic:
567 {
568 // Index of the bootstrap specifier in the operands array
569 int old_bs_i = scratch_cp->bootstrap_methods_attribute_index(scratch_i);
570 int new_bs_i = find_or_append_operand(scratch_cp, old_bs_i, merge_cp_p,
571 merge_cp_length_p);
572 // The bootstrap method NameAndType_info index
573 int old_ref_i = scratch_cp->bootstrap_name_and_type_ref_index_at(scratch_i);
574 int new_ref_i = find_or_append_indirect_entry(scratch_cp, old_ref_i, merge_cp_p,
575 merge_cp_length_p);
576 if (new_bs_i != old_bs_i) {
577 log_trace(redefine, class, constantpool)
578 ("Dynamic entry@%d bootstrap_method_attr_index change: %d to %d",
579 *merge_cp_length_p, old_bs_i, new_bs_i);
580 }
581 if (new_ref_i != old_ref_i) {
582 log_trace(redefine, class, constantpool)
583 ("Dynamic entry@%d name_and_type_index change: %d to %d", *merge_cp_length_p, old_ref_i, new_ref_i);
584 }
585
586 if (scratch_cp->tag_at(scratch_i).is_dynamic_constant())
587 (*merge_cp_p)->dynamic_constant_at_put(*merge_cp_length_p, new_bs_i, new_ref_i);
588 else
589 (*merge_cp_p)->invoke_dynamic_at_put(*merge_cp_length_p, new_bs_i, new_ref_i);
590 if (scratch_i != *merge_cp_length_p) {
591 // The new entry in *merge_cp_p is at a different index than
592 // the new entry in scratch_cp so we need to map the index values.
593 map_index(scratch_cp, scratch_i, *merge_cp_length_p);
594 }
595 (*merge_cp_length_p)++;
596 } break;
597
598 // At this stage, Class or UnresolvedClass could be in scratch_cp, but not
599 // ClassIndex
600 case JVM_CONSTANT_ClassIndex: // fall through
601
602 // Invalid is used as the tag for the second constant pool entry
603 // occupied by JVM_CONSTANT_Double or JVM_CONSTANT_Long. It should
604 // not be seen by itself.
605 case JVM_CONSTANT_Invalid: // fall through
606
607 // At this stage, String could be here, but not StringIndex
608 case JVM_CONSTANT_StringIndex: // fall through
609
610 // At this stage JVM_CONSTANT_UnresolvedClassInError should not be here
611 case JVM_CONSTANT_UnresolvedClassInError: // fall through
612
613 default:
614 {
615 // leave a breadcrumb
616 jbyte bad_value = scratch_cp->tag_at(scratch_i).value();
617 ShouldNotReachHere();
618 } break;
619 } // end switch tag value
620 } // end append_entry()
621
622
623 int VM_RedefineClasses::find_or_append_indirect_entry(const constantPoolHandle& scratch_cp,
624 int ref_i, constantPoolHandle *merge_cp_p, int *merge_cp_length_p) {
625
626 int new_ref_i = ref_i;
627 bool match = (ref_i < *merge_cp_length_p) &&
628 scratch_cp->compare_entry_to(ref_i, *merge_cp_p, ref_i);
629
630 if (!match) {
631 // forward reference in *merge_cp_p or not a direct match
632 int found_i = scratch_cp->find_matching_entry(ref_i, *merge_cp_p);
633 if (found_i != 0) {
634 guarantee(found_i != ref_i, "compare_entry_to() and find_matching_entry() do not agree");
635 // Found a matching entry somewhere else in *merge_cp_p so just need a mapping entry.
636 new_ref_i = found_i;
637 map_index(scratch_cp, ref_i, found_i);
638 } else {
639 // no match found so we have to append this entry to *merge_cp_p
640 append_entry(scratch_cp, ref_i, merge_cp_p, merge_cp_length_p);
641 // The above call to append_entry() can only append one entry
642 // so the post call query of *merge_cp_length_p is only for
643 // the sake of consistency.
644 new_ref_i = *merge_cp_length_p - 1;
645 }
646 }
647
648 return new_ref_i;
649 } // end find_or_append_indirect_entry()
650
651
652 // Append a bootstrap specifier into the merge_cp operands that is semantically equal
653 // to the scratch_cp operands bootstrap specifier passed by the old_bs_i index.
654 // Recursively append new merge_cp entries referenced by the new bootstrap specifier.
655 void VM_RedefineClasses::append_operand(const constantPoolHandle& scratch_cp, int old_bs_i,
656 constantPoolHandle *merge_cp_p, int *merge_cp_length_p) {
657
658 int old_ref_i = scratch_cp->operand_bootstrap_method_ref_index_at(old_bs_i);
659 int new_ref_i = find_or_append_indirect_entry(scratch_cp, old_ref_i, merge_cp_p,
660 merge_cp_length_p);
661 if (new_ref_i != old_ref_i) {
662 log_trace(redefine, class, constantpool)
663 ("operands entry@%d bootstrap method ref_index change: %d to %d", _operands_cur_length, old_ref_i, new_ref_i);
664 }
665
666 Array<u2>* merge_ops = (*merge_cp_p)->operands();
667 int new_bs_i = _operands_cur_length;
668 // We have _operands_cur_length == 0 when the merge_cp operands is empty yet.
669 // However, the operand_offset_at(0) was set in the extend_operands() call.
670 int new_base = (new_bs_i == 0) ? (*merge_cp_p)->operand_offset_at(0)
671 : (*merge_cp_p)->operand_next_offset_at(new_bs_i - 1);
672 int argc = scratch_cp->operand_argument_count_at(old_bs_i);
673
674 ConstantPool::operand_offset_at_put(merge_ops, _operands_cur_length, new_base);
675 merge_ops->at_put(new_base++, new_ref_i);
676 merge_ops->at_put(new_base++, argc);
677
678 for (int i = 0; i < argc; i++) {
679 int old_arg_ref_i = scratch_cp->operand_argument_index_at(old_bs_i, i);
680 int new_arg_ref_i = find_or_append_indirect_entry(scratch_cp, old_arg_ref_i, merge_cp_p,
681 merge_cp_length_p);
682 merge_ops->at_put(new_base++, new_arg_ref_i);
683 if (new_arg_ref_i != old_arg_ref_i) {
684 log_trace(redefine, class, constantpool)
685 ("operands entry@%d bootstrap method argument ref_index change: %d to %d",
686 _operands_cur_length, old_arg_ref_i, new_arg_ref_i);
687 }
688 }
689 if (old_bs_i != _operands_cur_length) {
690 // The bootstrap specifier in *merge_cp_p is at a different index than
691 // that in scratch_cp so we need to map the index values.
692 map_operand_index(old_bs_i, new_bs_i);
693 }
694 _operands_cur_length++;
695 } // end append_operand()
696
697
698 int VM_RedefineClasses::find_or_append_operand(const constantPoolHandle& scratch_cp,
699 int old_bs_i, constantPoolHandle *merge_cp_p, int *merge_cp_length_p) {
700
701 int new_bs_i = old_bs_i; // bootstrap specifier index
702 bool match = (old_bs_i < _operands_cur_length) &&
703 scratch_cp->compare_operand_to(old_bs_i, *merge_cp_p, old_bs_i);
704
705 if (!match) {
706 // forward reference in *merge_cp_p or not a direct match
707 int found_i = scratch_cp->find_matching_operand(old_bs_i, *merge_cp_p,
708 _operands_cur_length);
709 if (found_i != -1) {
710 guarantee(found_i != old_bs_i, "compare_operand_to() and find_matching_operand() disagree");
711 // found a matching operand somewhere else in *merge_cp_p so just need a mapping
712 new_bs_i = found_i;
713 map_operand_index(old_bs_i, found_i);
714 } else {
715 // no match found so we have to append this bootstrap specifier to *merge_cp_p
716 append_operand(scratch_cp, old_bs_i, merge_cp_p, merge_cp_length_p);
717 new_bs_i = _operands_cur_length - 1;
718 }
719 }
720 return new_bs_i;
721 } // end find_or_append_operand()
722
723
724 void VM_RedefineClasses::finalize_operands_merge(const constantPoolHandle& merge_cp, TRAPS) {
725 if (merge_cp->operands() == NULL) {
726 return;
727 }
728 // Shrink the merge_cp operands
729 merge_cp->shrink_operands(_operands_cur_length, CHECK);
730
731 if (log_is_enabled(Trace, redefine, class, constantpool)) {
732 // don't want to loop unless we are tracing
733 int count = 0;
734 for (int i = 1; i < _operands_index_map_p->length(); i++) {
735 int value = _operands_index_map_p->at(i);
736 if (value != -1) {
737 log_trace(redefine, class, constantpool)("operands_index_map[%d]: old=%d new=%d", count, i, value);
738 count++;
739 }
740 }
741 }
742 // Clean-up
743 _operands_index_map_p = NULL;
744 _operands_cur_length = 0;
745 _operands_index_map_count = 0;
746 } // end finalize_operands_merge()
747
748 // Symbol* comparator for qsort
749 // The caller must have an active ResourceMark.
750 static int symcmp(const void* a, const void* b) {
751 char* astr = (*(Symbol**)a)->as_C_string();
752 char* bstr = (*(Symbol**)b)->as_C_string();
753 return strcmp(astr, bstr);
754 }
755
756 // The caller must have an active ResourceMark.
757 static jvmtiError check_attribute_arrays(const char* attr_name,
758 InstanceKlass* the_class, InstanceKlass* scratch_class,
759 Array<u2>* the_array, Array<u2>* scr_array) {
760 bool the_array_exists = the_array != Universe::the_empty_short_array();
761 bool scr_array_exists = scr_array != Universe::the_empty_short_array();
762
763 int array_len = the_array->length();
764 if (the_array_exists && scr_array_exists) {
765 if (array_len != scr_array->length()) {
766 log_trace(redefine, class)
767 ("redefined class %s attribute change error: %s len=%d changed to len=%d",
768 the_class->external_name(), attr_name, array_len, scr_array->length());
769 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_CLASS_ATTRIBUTE_CHANGED;
770 }
771
772 // The order of entries in the attribute array is not specified so we
773 // have to explicitly check for the same contents. We do this by copying
774 // the referenced symbols into their own arrays, sorting them and then
775 // comparing each element pair.
776
777 Symbol** the_syms = NEW_RESOURCE_ARRAY_RETURN_NULL(Symbol*, array_len);
778 Symbol** scr_syms = NEW_RESOURCE_ARRAY_RETURN_NULL(Symbol*, array_len);
779
780 if (the_syms == NULL || scr_syms == NULL) {
781 return JVMTI_ERROR_OUT_OF_MEMORY;
782 }
783
784 for (int i = 0; i < array_len; i++) {
785 int the_cp_index = the_array->at(i);
786 int scr_cp_index = scr_array->at(i);
787 the_syms[i] = the_class->constants()->klass_name_at(the_cp_index);
788 scr_syms[i] = scratch_class->constants()->klass_name_at(scr_cp_index);
789 }
790
791 qsort(the_syms, array_len, sizeof(Symbol*), symcmp);
792 qsort(scr_syms, array_len, sizeof(Symbol*), symcmp);
793
794 for (int i = 0; i < array_len; i++) {
795 if (the_syms[i] != scr_syms[i]) {
796 log_info(redefine, class)
797 ("redefined class %s attribute change error: %s[%d]: %s changed to %s",
798 the_class->external_name(), attr_name, i,
799 the_syms[i]->as_C_string(), scr_syms[i]->as_C_string());
800 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_CLASS_ATTRIBUTE_CHANGED;
801 }
802 }
803 } else if (the_array_exists ^ scr_array_exists) {
804 const char* action_str = (the_array_exists) ? "removed" : "added";
805 log_info(redefine, class)
806 ("redefined class %s attribute change error: %s attribute %s",
807 the_class->external_name(), attr_name, action_str);
808 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_CLASS_ATTRIBUTE_CHANGED;
809 }
810 return JVMTI_ERROR_NONE;
811 }
812
813 static jvmtiError check_nest_attributes(InstanceKlass* the_class,
814 InstanceKlass* scratch_class) {
815 // Check whether the class NestHost attribute has been changed.
816 Thread* thread = Thread::current();
817 ResourceMark rm(thread);
818 u2 the_nest_host_idx = the_class->nest_host_index();
819 u2 scr_nest_host_idx = scratch_class->nest_host_index();
820
821 if (the_nest_host_idx != 0 && scr_nest_host_idx != 0) {
822 Symbol* the_sym = the_class->constants()->klass_name_at(the_nest_host_idx);
823 Symbol* scr_sym = scratch_class->constants()->klass_name_at(scr_nest_host_idx);
824 if (the_sym != scr_sym) {
825 log_info(redefine, class, nestmates)
826 ("redefined class %s attribute change error: NestHost class: %s replaced with: %s",
827 the_class->external_name(), the_sym->as_C_string(), scr_sym->as_C_string());
828 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_CLASS_ATTRIBUTE_CHANGED;
829 }
830 } else if ((the_nest_host_idx == 0) ^ (scr_nest_host_idx == 0)) {
831 const char* action_str = (the_nest_host_idx != 0) ? "removed" : "added";
832 log_info(redefine, class, nestmates)
833 ("redefined class %s attribute change error: NestHost attribute %s",
834 the_class->external_name(), action_str);
835 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_CLASS_ATTRIBUTE_CHANGED;
836 }
837
838 // Check whether the class NestMembers attribute has been changed.
839 return check_attribute_arrays("NestMembers",
840 the_class, scratch_class,
841 the_class->nest_members(),
842 scratch_class->nest_members());
843 }
844
845 // Return an error status if the class Record attribute was changed.
846 static jvmtiError check_record_attribute(InstanceKlass* the_class, InstanceKlass* scratch_class) {
847 // Get lists of record components.
848 Array<RecordComponent*>* the_record = the_class->record_components();
849 Array<RecordComponent*>* scr_record = scratch_class->record_components();
850 bool the_record_exists = the_record != NULL;
851 bool scr_record_exists = scr_record != NULL;
852
853 if (the_record_exists && scr_record_exists) {
854 int the_num_components = the_record->length();
855 int scr_num_components = scr_record->length();
856 if (the_num_components != scr_num_components) {
857 log_info(redefine, class, record)
858 ("redefined class %s attribute change error: Record num_components=%d changed to num_components=%d",
859 the_class->external_name(), the_num_components, scr_num_components);
860 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_CLASS_ATTRIBUTE_CHANGED;
861 }
862
863 // Compare each field in each record component.
864 ConstantPool* the_cp = the_class->constants();
865 ConstantPool* scr_cp = scratch_class->constants();
866 for (int x = 0; x < the_num_components; x++) {
867 RecordComponent* the_component = the_record->at(x);
868 RecordComponent* scr_component = scr_record->at(x);
869 const Symbol* const the_name = the_cp->symbol_at(the_component->name_index());
870 const Symbol* const scr_name = scr_cp->symbol_at(scr_component->name_index());
871 const Symbol* const the_descr = the_cp->symbol_at(the_component->descriptor_index());
872 const Symbol* const scr_descr = scr_cp->symbol_at(scr_component->descriptor_index());
873 if (the_name != scr_name || the_descr != scr_descr) {
874 log_info(redefine, class, record)
875 ("redefined class %s attribute change error: Record name_index, descriptor_index, and/or attributes_count changed",
876 the_class->external_name());
877 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_CLASS_ATTRIBUTE_CHANGED;
878 }
879
880 int the_gen_sig = the_component->generic_signature_index();
881 int scr_gen_sig = scr_component->generic_signature_index();
882 const Symbol* const the_gen_sig_sym = (the_gen_sig == 0 ? NULL :
883 the_cp->symbol_at(the_component->generic_signature_index()));
884 const Symbol* const scr_gen_sig_sym = (scr_gen_sig == 0 ? NULL :
885 scr_cp->symbol_at(scr_component->generic_signature_index()));
886 if (the_gen_sig_sym != scr_gen_sig_sym) {
887 log_info(redefine, class, record)
888 ("redefined class %s attribute change error: Record generic_signature attribute changed",
889 the_class->external_name());
890 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_CLASS_ATTRIBUTE_CHANGED;
891 }
892
893 // It's okay if a record component's annotations were changed.
894 }
895
896 } else if (the_record_exists ^ scr_record_exists) {
897 const char* action_str = (the_record_exists) ? "removed" : "added";
898 log_info(redefine, class, record)
899 ("redefined class %s attribute change error: Record attribute %s",
900 the_class->external_name(), action_str);
901 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_CLASS_ATTRIBUTE_CHANGED;
902 }
903
904 return JVMTI_ERROR_NONE;
905 }
906
907
908 static jvmtiError check_permitted_subclasses_attribute(InstanceKlass* the_class,
909 InstanceKlass* scratch_class) {
910 Thread* thread = Thread::current();
911 ResourceMark rm(thread);
912
913 // Check whether the class PermittedSubclasses attribute has been changed.
914 return check_attribute_arrays("PermittedSubclasses",
915 the_class, scratch_class,
916 the_class->permitted_subclasses(),
917 scratch_class->permitted_subclasses());
918 }
919
920 static bool can_add_or_delete(Method* m) {
921 // Compatibility mode
922 return (AllowRedefinitionToAddDeleteMethods &&
923 (m->is_private() && (m->is_static() || m->is_final())));
924 }
925
926 jvmtiError VM_RedefineClasses::compare_and_normalize_class_versions(
927 InstanceKlass* the_class,
928 InstanceKlass* scratch_class) {
929 int i;
930
931 // Check superclasses, or rather their names, since superclasses themselves can be
932 // requested to replace.
933 // Check for NULL superclass first since this might be java.lang.Object
934 if (the_class->super() != scratch_class->super() &&
935 (the_class->super() == NULL || scratch_class->super() == NULL ||
936 the_class->super()->name() !=
937 scratch_class->super()->name())) {
938 log_info(redefine, class, normalize)
939 ("redefined class %s superclass change error: superclass changed from %s to %s.",
940 the_class->external_name(),
941 the_class->super() == NULL ? "NULL" : the_class->super()->external_name(),
942 scratch_class->super() == NULL ? "NULL" : scratch_class->super()->external_name());
943 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_HIERARCHY_CHANGED;
944 }
945
946 // Check if the number, names and order of directly implemented interfaces are the same.
947 // I think in principle we should just check if the sets of names of directly implemented
948 // interfaces are the same, i.e. the order of declaration (which, however, if changed in the
949 // .java file, also changes in .class file) should not matter. However, comparing sets is
950 // technically a bit more difficult, and, more importantly, I am not sure at present that the
951 // order of interfaces does not matter on the implementation level, i.e. that the VM does not
952 // rely on it somewhere.
953 Array<InstanceKlass*>* k_interfaces = the_class->local_interfaces();
954 Array<InstanceKlass*>* k_new_interfaces = scratch_class->local_interfaces();
955 int n_intfs = k_interfaces->length();
956 if (n_intfs != k_new_interfaces->length()) {
957 log_info(redefine, class, normalize)
958 ("redefined class %s interfaces change error: number of implemented interfaces changed from %d to %d.",
959 the_class->external_name(), n_intfs, k_new_interfaces->length());
960 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_HIERARCHY_CHANGED;
961 }
962 for (i = 0; i < n_intfs; i++) {
963 if (k_interfaces->at(i)->name() !=
964 k_new_interfaces->at(i)->name()) {
965 log_info(redefine, class, normalize)
966 ("redefined class %s interfaces change error: interface changed from %s to %s.",
967 the_class->external_name(),
968 k_interfaces->at(i)->external_name(), k_new_interfaces->at(i)->external_name());
969 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_HIERARCHY_CHANGED;
970 }
971 }
972
973 // Check whether class is in the error init state.
974 if (the_class->is_in_error_state()) {
975 log_info(redefine, class, normalize)
976 ("redefined class %s is in error init state.", the_class->external_name());
977 // TBD #5057930: special error code is needed in 1.6
978 return JVMTI_ERROR_INVALID_CLASS;
979 }
980
981 // Check whether the nest-related attributes have been changed.
982 jvmtiError err = check_nest_attributes(the_class, scratch_class);
983 if (err != JVMTI_ERROR_NONE) {
984 return err;
985 }
986
987 // Check whether the Record attribute has been changed.
988 err = check_record_attribute(the_class, scratch_class);
989 if (err != JVMTI_ERROR_NONE) {
990 return err;
991 }
992
993 // Check whether the PermittedSubclasses attribute has been changed.
994 err = check_permitted_subclasses_attribute(the_class, scratch_class);
995 if (err != JVMTI_ERROR_NONE) {
996 return err;
997 }
998
999 // Check whether class modifiers are the same.
1000 jushort old_flags = (jushort) the_class->access_flags().get_flags();
1001 jushort new_flags = (jushort) scratch_class->access_flags().get_flags();
1002 if (old_flags != new_flags) {
1003 log_info(redefine, class, normalize)
1004 ("redefined class %s modifiers change error: modifiers changed from %d to %d.",
1005 the_class->external_name(), old_flags, new_flags);
1006 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_CLASS_MODIFIERS_CHANGED;
1007 }
1008
1009 // Check if the number, names, types and order of fields declared in these classes
1010 // are the same.
1011 JavaFieldStream old_fs(the_class);
1012 JavaFieldStream new_fs(scratch_class);
1013 for (; !old_fs.done() && !new_fs.done(); old_fs.next(), new_fs.next()) {
1014 // name and signature
1015 Symbol* name_sym1 = the_class->constants()->symbol_at(old_fs.name_index());
1016 Symbol* sig_sym1 = the_class->constants()->symbol_at(old_fs.signature_index());
1017 Symbol* name_sym2 = scratch_class->constants()->symbol_at(new_fs.name_index());
1018 Symbol* sig_sym2 = scratch_class->constants()->symbol_at(new_fs.signature_index());
1019 if (name_sym1 != name_sym2 || sig_sym1 != sig_sym2) {
1020 log_info(redefine, class, normalize)
1021 ("redefined class %s fields change error: field %s %s changed to %s %s.",
1022 the_class->external_name(),
1023 sig_sym1->as_C_string(), name_sym1->as_C_string(),
1024 sig_sym2->as_C_string(), name_sym2->as_C_string());
1025 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_SCHEMA_CHANGED;
1026 }
1027 // offset
1028 if (old_fs.offset() != new_fs.offset()) {
1029 log_info(redefine, class, normalize)
1030 ("redefined class %s field %s change error: offset changed from %d to %d.",
1031 the_class->external_name(), name_sym2->as_C_string(), old_fs.offset(), new_fs.offset());
1032 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_SCHEMA_CHANGED;
1033 }
1034 // access
1035 old_flags = old_fs.access_flags().as_short();
1036 new_flags = new_fs.access_flags().as_short();
1037 if ((old_flags ^ new_flags) & JVM_RECOGNIZED_FIELD_MODIFIERS) {
1038 log_info(redefine, class, normalize)
1039 ("redefined class %s field %s change error: modifiers changed from %d to %d.",
1040 the_class->external_name(), name_sym2->as_C_string(), old_flags, new_flags);
1041 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_SCHEMA_CHANGED;
1042 }
1043 }
1044
1045 // If both streams aren't done then we have a differing number of
1046 // fields.
1047 if (!old_fs.done() || !new_fs.done()) {
1048 const char* action = old_fs.done() ? "added" : "deleted";
1049 log_info(redefine, class, normalize)
1050 ("redefined class %s fields change error: some fields were %s.",
1051 the_class->external_name(), action);
1052 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_SCHEMA_CHANGED;
1053 }
1054
1055 // Do a parallel walk through the old and new methods. Detect
1056 // cases where they match (exist in both), have been added in
1057 // the new methods, or have been deleted (exist only in the
1058 // old methods). The class file parser places methods in order
1059 // by method name, but does not order overloaded methods by
1060 // signature. In order to determine what fate befell the methods,
1061 // this code places the overloaded new methods that have matching
1062 // old methods in the same order as the old methods and places
1063 // new overloaded methods at the end of overloaded methods of
1064 // that name. The code for this order normalization is adapted
1065 // from the algorithm used in InstanceKlass::find_method().
1066 // Since we are swapping out of order entries as we find them,
1067 // we only have to search forward through the overloaded methods.
1068 // Methods which are added and have the same name as an existing
1069 // method (but different signature) will be put at the end of
1070 // the methods with that name, and the name mismatch code will
1071 // handle them.
1072 Array<Method*>* k_old_methods(the_class->methods());
1073 Array<Method*>* k_new_methods(scratch_class->methods());
1074 int n_old_methods = k_old_methods->length();
1075 int n_new_methods = k_new_methods->length();
1076 Thread* thread = Thread::current();
1077
1078 int ni = 0;
1079 int oi = 0;
1080 while (true) {
1081 Method* k_old_method;
1082 Method* k_new_method;
1083 enum { matched, added, deleted, undetermined } method_was = undetermined;
1084
1085 if (oi >= n_old_methods) {
1086 if (ni >= n_new_methods) {
1087 break; // we've looked at everything, done
1088 }
1089 // New method at the end
1090 k_new_method = k_new_methods->at(ni);
1091 method_was = added;
1092 } else if (ni >= n_new_methods) {
1093 // Old method, at the end, is deleted
1094 k_old_method = k_old_methods->at(oi);
1095 method_was = deleted;
1096 } else {
1097 // There are more methods in both the old and new lists
1098 k_old_method = k_old_methods->at(oi);
1099 k_new_method = k_new_methods->at(ni);
1100 if (k_old_method->name() != k_new_method->name()) {
1101 // Methods are sorted by method name, so a mismatch means added
1102 // or deleted
1103 if (k_old_method->name()->fast_compare(k_new_method->name()) > 0) {
1104 method_was = added;
1105 } else {
1106 method_was = deleted;
1107 }
1108 } else if (k_old_method->signature() == k_new_method->signature()) {
1109 // Both the name and signature match
1110 method_was = matched;
1111 } else {
1112 // The name matches, but the signature doesn't, which means we have to
1113 // search forward through the new overloaded methods.
1114 int nj; // outside the loop for post-loop check
1115 for (nj = ni + 1; nj < n_new_methods; nj++) {
1116 Method* m = k_new_methods->at(nj);
1117 if (k_old_method->name() != m->name()) {
1118 // reached another method name so no more overloaded methods
1119 method_was = deleted;
1120 break;
1121 }
1122 if (k_old_method->signature() == m->signature()) {
1123 // found a match so swap the methods
1124 k_new_methods->at_put(ni, m);
1125 k_new_methods->at_put(nj, k_new_method);
1126 k_new_method = m;
1127 method_was = matched;
1128 break;
1129 }
1130 }
1131
1132 if (nj >= n_new_methods) {
1133 // reached the end without a match; so method was deleted
1134 method_was = deleted;
1135 }
1136 }
1137 }
1138
1139 switch (method_was) {
1140 case matched:
1141 // methods match, be sure modifiers do too
1142 old_flags = (jushort) k_old_method->access_flags().get_flags();
1143 new_flags = (jushort) k_new_method->access_flags().get_flags();
1144 if ((old_flags ^ new_flags) & ~(JVM_ACC_NATIVE)) {
1145 log_info(redefine, class, normalize)
1146 ("redefined class %s method %s modifiers error: modifiers changed from %d to %d",
1147 the_class->external_name(), k_old_method->name_and_sig_as_C_string(), old_flags, new_flags);
1148 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_METHOD_MODIFIERS_CHANGED;
1149 }
1150 {
1151 u2 new_num = k_new_method->method_idnum();
1152 u2 old_num = k_old_method->method_idnum();
1153 if (new_num != old_num) {
1154 Method* idnum_owner = scratch_class->method_with_idnum(old_num);
1155 if (idnum_owner != NULL) {
1156 // There is already a method assigned this idnum -- switch them
1157 // Take current and original idnum from the new_method
1158 idnum_owner->set_method_idnum(new_num);
1159 idnum_owner->set_orig_method_idnum(k_new_method->orig_method_idnum());
1160 }
1161 // Take current and original idnum from the old_method
1162 k_new_method->set_method_idnum(old_num);
1163 k_new_method->set_orig_method_idnum(k_old_method->orig_method_idnum());
1164 if (thread->has_pending_exception()) {
1165 return JVMTI_ERROR_OUT_OF_MEMORY;
1166 }
1167 }
1168 }
1169 log_trace(redefine, class, normalize)
1170 ("Method matched: new: %s [%d] == old: %s [%d]",
1171 k_new_method->name_and_sig_as_C_string(), ni, k_old_method->name_and_sig_as_C_string(), oi);
1172 // advance to next pair of methods
1173 ++oi;
1174 ++ni;
1175 break;
1176 case added:
1177 // method added, see if it is OK
1178 if (!can_add_or_delete(k_new_method)) {
1179 log_info(redefine, class, normalize)
1180 ("redefined class %s methods error: added method: %s [%d]",
1181 the_class->external_name(), k_new_method->name_and_sig_as_C_string(), ni);
1182 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_METHOD_ADDED;
1183 }
1184 {
1185 u2 num = the_class->next_method_idnum();
1186 if (num == ConstMethod::UNSET_IDNUM) {
1187 // cannot add any more methods
1188 log_info(redefine, class, normalize)
1189 ("redefined class %s methods error: can't create ID for new method %s [%d]",
1190 the_class->external_name(), k_new_method->name_and_sig_as_C_string(), ni);
1191 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_METHOD_ADDED;
1192 }
1193 u2 new_num = k_new_method->method_idnum();
1194 Method* idnum_owner = scratch_class->method_with_idnum(num);
1195 if (idnum_owner != NULL) {
1196 // There is already a method assigned this idnum -- switch them
1197 // Take current and original idnum from the new_method
1198 idnum_owner->set_method_idnum(new_num);
1199 idnum_owner->set_orig_method_idnum(k_new_method->orig_method_idnum());
1200 }
1201 k_new_method->set_method_idnum(num);
1202 k_new_method->set_orig_method_idnum(num);
1203 if (thread->has_pending_exception()) {
1204 return JVMTI_ERROR_OUT_OF_MEMORY;
1205 }
1206 }
1207 log_trace(redefine, class, normalize)
1208 ("Method added: new: %s [%d]", k_new_method->name_and_sig_as_C_string(), ni);
1209 ++ni; // advance to next new method
1210 break;
1211 case deleted:
1212 // method deleted, see if it is OK
1213 if (!can_add_or_delete(k_old_method)) {
1214 log_info(redefine, class, normalize)
1215 ("redefined class %s methods error: deleted method %s [%d]",
1216 the_class->external_name(), k_old_method->name_and_sig_as_C_string(), oi);
1217 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_METHOD_DELETED;
1218 }
1219 log_trace(redefine, class, normalize)
1220 ("Method deleted: old: %s [%d]", k_old_method->name_and_sig_as_C_string(), oi);
1221 ++oi; // advance to next old method
1222 break;
1223 default:
1224 ShouldNotReachHere();
1225 }
1226 }
1227
1228 return JVMTI_ERROR_NONE;
1229 }
1230
1231
1232 // Find new constant pool index value for old constant pool index value
1233 // by seaching the index map. Returns zero (0) if there is no mapped
1234 // value for the old constant pool index.
1235 int VM_RedefineClasses::find_new_index(int old_index) {
1236 if (_index_map_count == 0) {
1237 // map is empty so nothing can be found
1238 return 0;
1239 }
1240
1241 if (old_index < 1 || old_index >= _index_map_p->length()) {
1242 // The old_index is out of range so it is not mapped. This should
1243 // not happen in regular constant pool merging use, but it can
1244 // happen if a corrupt annotation is processed.
1245 return 0;
1246 }
1247
1248 int value = _index_map_p->at(old_index);
1249 if (value == -1) {
1250 // the old_index is not mapped
1251 return 0;
1252 }
1253
1254 return value;
1255 } // end find_new_index()
1256
1257
1258 // Find new bootstrap specifier index value for old bootstrap specifier index
1259 // value by seaching the index map. Returns unused index (-1) if there is
1260 // no mapped value for the old bootstrap specifier index.
1261 int VM_RedefineClasses::find_new_operand_index(int old_index) {
1262 if (_operands_index_map_count == 0) {
1263 // map is empty so nothing can be found
1264 return -1;
1265 }
1266
1267 if (old_index == -1 || old_index >= _operands_index_map_p->length()) {
1268 // The old_index is out of range so it is not mapped.
1269 // This should not happen in regular constant pool merging use.
1270 return -1;
1271 }
1272
1273 int value = _operands_index_map_p->at(old_index);
1274 if (value == -1) {
1275 // the old_index is not mapped
1276 return -1;
1277 }
1278
1279 return value;
1280 } // end find_new_operand_index()
1281
1282
1283 // Returns true if the current mismatch is due to a resolved/unresolved
1284 // class pair. Otherwise, returns false.
1285 bool VM_RedefineClasses::is_unresolved_class_mismatch(const constantPoolHandle& cp1,
1286 int index1, const constantPoolHandle& cp2, int index2) {
1287
1288 jbyte t1 = cp1->tag_at(index1).value();
1289 if (t1 != JVM_CONSTANT_Class && t1 != JVM_CONSTANT_UnresolvedClass) {
1290 return false; // wrong entry type; not our special case
1291 }
1292
1293 jbyte t2 = cp2->tag_at(index2).value();
1294 if (t2 != JVM_CONSTANT_Class && t2 != JVM_CONSTANT_UnresolvedClass) {
1295 return false; // wrong entry type; not our special case
1296 }
1297
1298 if (t1 == t2) {
1299 return false; // not a mismatch; not our special case
1300 }
1301
1302 char *s1 = cp1->klass_name_at(index1)->as_C_string();
1303 char *s2 = cp2->klass_name_at(index2)->as_C_string();
1304 if (strcmp(s1, s2) != 0) {
1305 return false; // strings don't match; not our special case
1306 }
1307
1308 return true; // made it through the gauntlet; this is our special case
1309 } // end is_unresolved_class_mismatch()
1310
1311
1312 // The bug 6214132 caused the verification to fail.
1313 // 1. What's done in RedefineClasses() before verification:
1314 // a) A reference to the class being redefined (_the_class) and a
1315 // reference to new version of the class (_scratch_class) are
1316 // saved here for use during the bytecode verification phase of
1317 // RedefineClasses.
1318 // b) The _java_mirror field from _the_class is copied to the
1319 // _java_mirror field in _scratch_class. This means that a jclass
1320 // returned for _the_class or _scratch_class will refer to the
1321 // same Java mirror. The verifier will see the "one true mirror"
1322 // for the class being verified.
1323 // 2. See comments in JvmtiThreadState for what is done during verification.
1324
1325 class RedefineVerifyMark : public StackObj {
1326 private:
1327 JvmtiThreadState* _state;
1328 Klass* _scratch_class;
1329 Handle _scratch_mirror;
1330
1331 public:
1332
1333 RedefineVerifyMark(Klass* the_class, Klass* scratch_class,
1334 JvmtiThreadState* state) : _state(state), _scratch_class(scratch_class)
1335 {
1336 _state->set_class_versions_map(the_class, scratch_class);
1337 _scratch_mirror = Handle(_state->get_thread(), _scratch_class->java_mirror());
1338 _scratch_class->replace_java_mirror(the_class->java_mirror());
1339 }
1340
1341 ~RedefineVerifyMark() {
1342 // Restore the scratch class's mirror, so when scratch_class is removed
1343 // the correct mirror pointing to it can be cleared.
1344 _scratch_class->replace_java_mirror(_scratch_mirror());
1345 _state->clear_class_versions_map();
1346 }
1347 };
1348
1349
1350 jvmtiError VM_RedefineClasses::load_new_class_versions() {
1351
1352 // For consistency allocate memory using os::malloc wrapper.
1353 _scratch_classes = (InstanceKlass**)
1354 os::malloc(sizeof(InstanceKlass*) * _class_count, mtClass);
1355 if (_scratch_classes == NULL) {
1356 return JVMTI_ERROR_OUT_OF_MEMORY;
1357 }
1358 // Zero initialize the _scratch_classes array.
1359 for (int i = 0; i < _class_count; i++) {
1360 _scratch_classes[i] = NULL;
1361 }
1362
1363 JavaThread* current = JavaThread::current();
1364 ResourceMark rm(current);
1365
1366 JvmtiThreadState *state = JvmtiThreadState::state_for(current);
1367 // state can only be NULL if the current thread is exiting which
1368 // should not happen since we're trying to do a RedefineClasses
1369 guarantee(state != NULL, "exiting thread calling load_new_class_versions");
1370 for (int i = 0; i < _class_count; i++) {
1371 // Create HandleMark so that any handles created while loading new class
1372 // versions are deleted. Constant pools are deallocated while merging
1373 // constant pools
1374 HandleMark hm(current);
1375 InstanceKlass* the_class = get_ik(_class_defs[i].klass);
1376
1377 log_debug(redefine, class, load)
1378 ("loading name=%s kind=%d (avail_mem=" UINT64_FORMAT "K)",
1379 the_class->external_name(), _class_load_kind, os::available_memory() >> 10);
1380
1381 ClassFileStream st((u1*)_class_defs[i].class_bytes,
1382 _class_defs[i].class_byte_count,
1383 "__VM_RedefineClasses__",
1384 ClassFileStream::verify);
1385
1386 // Set redefined class handle in JvmtiThreadState class.
1387 // This redefined class is sent to agent event handler for class file
1388 // load hook event.
1389 state->set_class_being_redefined(the_class, _class_load_kind);
1390
1391 JavaThread* THREAD = current; // For exception macros.
1392 ExceptionMark em(THREAD);
1393 Handle protection_domain(THREAD, the_class->protection_domain());
1394 ClassLoadInfo cl_info(protection_domain);
1395 // Parse and create a class from the bytes, but this class isn't added
1396 // to the dictionary, so do not call resolve_from_stream.
1397 InstanceKlass* scratch_class = KlassFactory::create_from_stream(&st,
1398 the_class->name(),
1399 the_class->class_loader_data(),
1400 cl_info,
1401 THREAD);
1402
1403 // Clear class_being_redefined just to be sure.
1404 state->clear_class_being_redefined();
1405
1406 // TODO: if this is retransform, and nothing changed we can skip it
1407
1408 // Need to clean up allocated InstanceKlass if there's an error so assign
1409 // the result here. Caller deallocates all the scratch classes in case of
1410 // an error.
1411 _scratch_classes[i] = scratch_class;
1412
1413 if (HAS_PENDING_EXCEPTION) {
1414 Symbol* ex_name = PENDING_EXCEPTION->klass()->name();
1415 log_info(redefine, class, load, exceptions)("create_from_stream exception: '%s'", ex_name->as_C_string());
1416 CLEAR_PENDING_EXCEPTION;
1417
1418 if (ex_name == vmSymbols::java_lang_UnsupportedClassVersionError()) {
1419 return JVMTI_ERROR_UNSUPPORTED_VERSION;
1420 } else if (ex_name == vmSymbols::java_lang_ClassFormatError()) {
1421 return JVMTI_ERROR_INVALID_CLASS_FORMAT;
1422 } else if (ex_name == vmSymbols::java_lang_ClassCircularityError()) {
1423 return JVMTI_ERROR_CIRCULAR_CLASS_DEFINITION;
1424 } else if (ex_name == vmSymbols::java_lang_NoClassDefFoundError()) {
1425 // The message will be "XXX (wrong name: YYY)"
1426 return JVMTI_ERROR_NAMES_DONT_MATCH;
1427 } else if (ex_name == vmSymbols::java_lang_OutOfMemoryError()) {
1428 return JVMTI_ERROR_OUT_OF_MEMORY;
1429 } else { // Just in case more exceptions can be thrown..
1430 return JVMTI_ERROR_FAILS_VERIFICATION;
1431 }
1432 }
1433
1434 // Ensure class is linked before redefine
1435 if (!the_class->is_linked()) {
1436 the_class->link_class(THREAD);
1437 if (HAS_PENDING_EXCEPTION) {
1438 Symbol* ex_name = PENDING_EXCEPTION->klass()->name();
1439 oop message = java_lang_Throwable::message(PENDING_EXCEPTION);
1440 if (message != NULL) {
1441 char* ex_msg = java_lang_String::as_utf8_string(message);
1442 log_info(redefine, class, load, exceptions)("link_class exception: '%s %s'",
1443 ex_name->as_C_string(), ex_msg);
1444 } else {
1445 log_info(redefine, class, load, exceptions)("link_class exception: '%s'",
1446 ex_name->as_C_string());
1447 }
1448 CLEAR_PENDING_EXCEPTION;
1449 if (ex_name == vmSymbols::java_lang_OutOfMemoryError()) {
1450 return JVMTI_ERROR_OUT_OF_MEMORY;
1451 } else if (ex_name == vmSymbols::java_lang_NoClassDefFoundError()) {
1452 return JVMTI_ERROR_INVALID_CLASS;
1453 } else {
1454 return JVMTI_ERROR_INTERNAL;
1455 }
1456 }
1457 }
1458
1459 // Do the validity checks in compare_and_normalize_class_versions()
1460 // before verifying the byte codes. By doing these checks first, we
1461 // limit the number of functions that require redirection from
1462 // the_class to scratch_class. In particular, we don't have to
1463 // modify JNI GetSuperclass() and thus won't change its performance.
1464 jvmtiError res = compare_and_normalize_class_versions(the_class,
1465 scratch_class);
1466 if (res != JVMTI_ERROR_NONE) {
1467 return res;
1468 }
1469
1470 // verify what the caller passed us
1471 {
1472 // The bug 6214132 caused the verification to fail.
1473 // Information about the_class and scratch_class is temporarily
1474 // recorded into jvmtiThreadState. This data is used to redirect
1475 // the_class to scratch_class in the JVM_* functions called by the
1476 // verifier. Please, refer to jvmtiThreadState.hpp for the detailed
1477 // description.
1478 RedefineVerifyMark rvm(the_class, scratch_class, state);
1479 Verifier::verify(scratch_class, true, THREAD);
1480 }
1481
1482 if (HAS_PENDING_EXCEPTION) {
1483 Symbol* ex_name = PENDING_EXCEPTION->klass()->name();
1484 log_info(redefine, class, load, exceptions)("verify_byte_codes exception: '%s'", ex_name->as_C_string());
1485 CLEAR_PENDING_EXCEPTION;
1486 if (ex_name == vmSymbols::java_lang_OutOfMemoryError()) {
1487 return JVMTI_ERROR_OUT_OF_MEMORY;
1488 } else {
1489 // tell the caller the bytecodes are bad
1490 return JVMTI_ERROR_FAILS_VERIFICATION;
1491 }
1492 }
1493
1494 res = merge_cp_and_rewrite(the_class, scratch_class, THREAD);
1495 if (HAS_PENDING_EXCEPTION) {
1496 Symbol* ex_name = PENDING_EXCEPTION->klass()->name();
1497 log_info(redefine, class, load, exceptions)("merge_cp_and_rewrite 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 return JVMTI_ERROR_INTERNAL;
1503 }
1504 }
1505
1506 #ifdef ASSERT
1507 {
1508 // verify what we have done during constant pool merging
1509 {
1510 RedefineVerifyMark rvm(the_class, scratch_class, state);
1511 Verifier::verify(scratch_class, true, THREAD);
1512 }
1513
1514 if (HAS_PENDING_EXCEPTION) {
1515 Symbol* ex_name = PENDING_EXCEPTION->klass()->name();
1516 log_info(redefine, class, load, exceptions)
1517 ("verify_byte_codes post merge-CP exception: '%s'", ex_name->as_C_string());
1518 CLEAR_PENDING_EXCEPTION;
1519 if (ex_name == vmSymbols::java_lang_OutOfMemoryError()) {
1520 return JVMTI_ERROR_OUT_OF_MEMORY;
1521 } else {
1522 // tell the caller that constant pool merging screwed up
1523 return JVMTI_ERROR_INTERNAL;
1524 }
1525 }
1526 }
1527 #endif // ASSERT
1528
1529 Rewriter::rewrite(scratch_class, THREAD);
1530 if (!HAS_PENDING_EXCEPTION) {
1531 scratch_class->link_methods(THREAD);
1532 }
1533 if (HAS_PENDING_EXCEPTION) {
1534 Symbol* ex_name = PENDING_EXCEPTION->klass()->name();
1535 log_info(redefine, class, load, exceptions)
1536 ("Rewriter::rewrite or link_methods exception: '%s'", ex_name->as_C_string());
1537 CLEAR_PENDING_EXCEPTION;
1538 if (ex_name == vmSymbols::java_lang_OutOfMemoryError()) {
1539 return JVMTI_ERROR_OUT_OF_MEMORY;
1540 } else {
1541 return JVMTI_ERROR_INTERNAL;
1542 }
1543 }
1544
1545 log_debug(redefine, class, load)
1546 ("loaded name=%s (avail_mem=" UINT64_FORMAT "K)", the_class->external_name(), os::available_memory() >> 10);
1547 }
1548
1549 return JVMTI_ERROR_NONE;
1550 }
1551
1552
1553 // Map old_index to new_index as needed. scratch_cp is only needed
1554 // for log calls.
1555 void VM_RedefineClasses::map_index(const constantPoolHandle& scratch_cp,
1556 int old_index, int new_index) {
1557 if (find_new_index(old_index) != 0) {
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 _index_map_p->at_put(old_index, new_index);
1568 _index_map_count++;
1569
1570 log_trace(redefine, class, constantpool)
1571 ("mapped tag %d at index %d to %d", scratch_cp->tag_at(old_index).value(), old_index, new_index);
1572 } // end map_index()
1573
1574
1575 // Map old_index to new_index as needed.
1576 void VM_RedefineClasses::map_operand_index(int old_index, int new_index) {
1577 if (find_new_operand_index(old_index) != -1) {
1578 // old_index is already mapped
1579 return;
1580 }
1581
1582 if (old_index == new_index) {
1583 // no mapping is needed
1584 return;
1585 }
1586
1587 _operands_index_map_p->at_put(old_index, new_index);
1588 _operands_index_map_count++;
1589
1590 log_trace(redefine, class, constantpool)("mapped bootstrap specifier at index %d to %d", old_index, new_index);
1591 } // end map_index()
1592
1593
1594 // Merge old_cp and scratch_cp and return the results of the merge via
1595 // merge_cp_p. The number of entries in *merge_cp_p is returned via
1596 // merge_cp_length_p. The entries in old_cp occupy the same locations
1597 // in *merge_cp_p. Also creates a map of indices from entries in
1598 // scratch_cp to the corresponding entry in *merge_cp_p. Index map
1599 // entries are only created for entries in scratch_cp that occupy a
1600 // different location in *merged_cp_p.
1601 bool VM_RedefineClasses::merge_constant_pools(const constantPoolHandle& old_cp,
1602 const constantPoolHandle& scratch_cp, constantPoolHandle *merge_cp_p,
1603 int *merge_cp_length_p, TRAPS) {
1604
1605 if (merge_cp_p == NULL) {
1606 assert(false, "caller must provide scratch constantPool");
1607 return false; // robustness
1608 }
1609 if (merge_cp_length_p == NULL) {
1610 assert(false, "caller must provide scratch CP length");
1611 return false; // robustness
1612 }
1613 // Worst case we need old_cp->length() + scratch_cp()->length(),
1614 // but the caller might be smart so make sure we have at least
1615 // the minimum.
1616 if ((*merge_cp_p)->length() < old_cp->length()) {
1617 assert(false, "merge area too small");
1618 return false; // robustness
1619 }
1620
1621 log_info(redefine, class, constantpool)("old_cp_len=%d, scratch_cp_len=%d", old_cp->length(), scratch_cp->length());
1622
1623 {
1624 // Pass 0:
1625 // The old_cp is copied to *merge_cp_p; this means that any code
1626 // using old_cp does not have to change. This work looks like a
1627 // perfect fit for ConstantPool*::copy_cp_to(), but we need to
1628 // handle one special case:
1629 // - revert JVM_CONSTANT_Class to JVM_CONSTANT_UnresolvedClass
1630 // This will make verification happy.
1631
1632 int old_i; // index into old_cp
1633
1634 // index zero (0) is not used in constantPools
1635 for (old_i = 1; old_i < old_cp->length(); old_i++) {
1636 // leave debugging crumb
1637 jbyte old_tag = old_cp->tag_at(old_i).value();
1638 switch (old_tag) {
1639 case JVM_CONSTANT_Class:
1640 case JVM_CONSTANT_UnresolvedClass:
1641 // revert the copy to JVM_CONSTANT_UnresolvedClass
1642 // May be resolving while calling this so do the same for
1643 // JVM_CONSTANT_UnresolvedClass (klass_name_at() deals with transition)
1644 (*merge_cp_p)->temp_unresolved_klass_at_put(old_i,
1645 old_cp->klass_name_index_at(old_i));
1646 break;
1647
1648 case JVM_CONSTANT_Double:
1649 case JVM_CONSTANT_Long:
1650 // just copy the entry to *merge_cp_p, but double and long take
1651 // two constant pool entries
1652 ConstantPool::copy_entry_to(old_cp, old_i, *merge_cp_p, old_i);
1653 old_i++;
1654 break;
1655
1656 default:
1657 // just copy the entry to *merge_cp_p
1658 ConstantPool::copy_entry_to(old_cp, old_i, *merge_cp_p, old_i);
1659 break;
1660 }
1661 } // end for each old_cp entry
1662
1663 ConstantPool::copy_operands(old_cp, *merge_cp_p, CHECK_false);
1664 (*merge_cp_p)->extend_operands(scratch_cp, CHECK_false);
1665
1666 // We don't need to sanity check that *merge_cp_length_p is within
1667 // *merge_cp_p bounds since we have the minimum on-entry check above.
1668 (*merge_cp_length_p) = old_i;
1669 }
1670
1671 // merge_cp_len should be the same as old_cp->length() at this point
1672 // so this trace message is really a "warm-and-breathing" message.
1673 log_debug(redefine, class, constantpool)("after pass 0: merge_cp_len=%d", *merge_cp_length_p);
1674
1675 int scratch_i; // index into scratch_cp
1676 {
1677 // Pass 1a:
1678 // Compare scratch_cp entries to the old_cp entries that we have
1679 // already copied to *merge_cp_p. In this pass, we are eliminating
1680 // exact duplicates (matching entry at same index) so we only
1681 // compare entries in the common indice range.
1682 int increment = 1;
1683 int pass1a_length = MIN2(old_cp->length(), scratch_cp->length());
1684 for (scratch_i = 1; scratch_i < pass1a_length; scratch_i += increment) {
1685 switch (scratch_cp->tag_at(scratch_i).value()) {
1686 case JVM_CONSTANT_Double:
1687 case JVM_CONSTANT_Long:
1688 // double and long take two constant pool entries
1689 increment = 2;
1690 break;
1691
1692 default:
1693 increment = 1;
1694 break;
1695 }
1696
1697 bool match = scratch_cp->compare_entry_to(scratch_i, *merge_cp_p, scratch_i);
1698 if (match) {
1699 // found a match at the same index so nothing more to do
1700 continue;
1701 } else if (is_unresolved_class_mismatch(scratch_cp, scratch_i,
1702 *merge_cp_p, scratch_i)) {
1703 // The mismatch in compare_entry_to() above is because of a
1704 // resolved versus unresolved class entry at the same index
1705 // with the same string value. Since Pass 0 reverted any
1706 // class entries to unresolved class entries in *merge_cp_p,
1707 // we go with the unresolved class entry.
1708 continue;
1709 }
1710
1711 int found_i = scratch_cp->find_matching_entry(scratch_i, *merge_cp_p);
1712 if (found_i != 0) {
1713 guarantee(found_i != scratch_i,
1714 "compare_entry_to() and find_matching_entry() do not agree");
1715
1716 // Found a matching entry somewhere else in *merge_cp_p so
1717 // just need a mapping entry.
1718 map_index(scratch_cp, scratch_i, found_i);
1719 continue;
1720 }
1721
1722 // The find_matching_entry() call above could fail to find a match
1723 // due to a resolved versus unresolved class or string entry situation
1724 // like we solved above with the is_unresolved_*_mismatch() calls.
1725 // However, we would have to call is_unresolved_*_mismatch() over
1726 // all of *merge_cp_p (potentially) and that doesn't seem to be
1727 // worth the time.
1728
1729 // No match found so we have to append this entry and any unique
1730 // referenced entries to *merge_cp_p.
1731 append_entry(scratch_cp, scratch_i, merge_cp_p, merge_cp_length_p);
1732 }
1733 }
1734
1735 log_debug(redefine, class, constantpool)
1736 ("after pass 1a: merge_cp_len=%d, scratch_i=%d, index_map_len=%d",
1737 *merge_cp_length_p, scratch_i, _index_map_count);
1738
1739 if (scratch_i < scratch_cp->length()) {
1740 // Pass 1b:
1741 // old_cp is smaller than scratch_cp so there are entries in
1742 // scratch_cp that we have not yet processed. We take care of
1743 // those now.
1744 int increment = 1;
1745 for (; scratch_i < scratch_cp->length(); scratch_i += increment) {
1746 switch (scratch_cp->tag_at(scratch_i).value()) {
1747 case JVM_CONSTANT_Double:
1748 case JVM_CONSTANT_Long:
1749 // double and long take two constant pool entries
1750 increment = 2;
1751 break;
1752
1753 default:
1754 increment = 1;
1755 break;
1756 }
1757
1758 int found_i =
1759 scratch_cp->find_matching_entry(scratch_i, *merge_cp_p);
1760 if (found_i != 0) {
1761 // Found a matching entry somewhere else in *merge_cp_p so
1762 // just need a mapping entry.
1763 map_index(scratch_cp, scratch_i, found_i);
1764 continue;
1765 }
1766
1767 // No match found so we have to append this entry and any unique
1768 // referenced entries to *merge_cp_p.
1769 append_entry(scratch_cp, scratch_i, merge_cp_p, merge_cp_length_p);
1770 }
1771
1772 log_debug(redefine, class, constantpool)
1773 ("after pass 1b: merge_cp_len=%d, scratch_i=%d, index_map_len=%d",
1774 *merge_cp_length_p, scratch_i, _index_map_count);
1775 }
1776 finalize_operands_merge(*merge_cp_p, CHECK_false);
1777
1778 return true;
1779 } // end merge_constant_pools()
1780
1781
1782 // Scoped object to clean up the constant pool(s) created for merging
1783 class MergeCPCleaner {
1784 ClassLoaderData* _loader_data;
1785 ConstantPool* _cp;
1786 ConstantPool* _scratch_cp;
1787 public:
1788 MergeCPCleaner(ClassLoaderData* loader_data, ConstantPool* merge_cp) :
1789 _loader_data(loader_data), _cp(merge_cp), _scratch_cp(NULL) {}
1790 ~MergeCPCleaner() {
1791 _loader_data->add_to_deallocate_list(_cp);
1792 if (_scratch_cp != NULL) {
1793 _loader_data->add_to_deallocate_list(_scratch_cp);
1794 }
1795 }
1796 void add_scratch_cp(ConstantPool* scratch_cp) { _scratch_cp = scratch_cp; }
1797 };
1798
1799 // Merge constant pools between the_class and scratch_class and
1800 // potentially rewrite bytecodes in scratch_class to use the merged
1801 // constant pool.
1802 jvmtiError VM_RedefineClasses::merge_cp_and_rewrite(
1803 InstanceKlass* the_class, InstanceKlass* scratch_class,
1804 TRAPS) {
1805 // worst case merged constant pool length is old and new combined
1806 int merge_cp_length = the_class->constants()->length()
1807 + scratch_class->constants()->length();
1808
1809 // Constant pools are not easily reused so we allocate a new one
1810 // each time.
1811 // merge_cp is created unsafe for concurrent GC processing. It
1812 // should be marked safe before discarding it. Even though
1813 // garbage, if it crosses a card boundary, it may be scanned
1814 // in order to find the start of the first complete object on the card.
1815 ClassLoaderData* loader_data = the_class->class_loader_data();
1816 ConstantPool* merge_cp_oop =
1817 ConstantPool::allocate(loader_data,
1818 merge_cp_length,
1819 CHECK_(JVMTI_ERROR_OUT_OF_MEMORY));
1820 MergeCPCleaner cp_cleaner(loader_data, merge_cp_oop);
1821
1822 HandleMark hm(THREAD); // make sure handles are cleared before
1823 // MergeCPCleaner clears out merge_cp_oop
1824 constantPoolHandle merge_cp(THREAD, merge_cp_oop);
1825
1826 // Get constants() from the old class because it could have been rewritten
1827 // while we were at a safepoint allocating a new constant pool.
1828 constantPoolHandle old_cp(THREAD, the_class->constants());
1829 constantPoolHandle scratch_cp(THREAD, scratch_class->constants());
1830
1831 // If the length changed, the class was redefined out from under us. Return
1832 // an error.
1833 if (merge_cp_length != the_class->constants()->length()
1834 + scratch_class->constants()->length()) {
1835 return JVMTI_ERROR_INTERNAL;
1836 }
1837
1838 // Update the version number of the constant pools (may keep scratch_cp)
1839 merge_cp->increment_and_save_version(old_cp->version());
1840 scratch_cp->increment_and_save_version(old_cp->version());
1841
1842 ResourceMark rm(THREAD);
1843 _index_map_count = 0;
1844 _index_map_p = new intArray(scratch_cp->length(), scratch_cp->length(), -1);
1845
1846 _operands_cur_length = ConstantPool::operand_array_length(old_cp->operands());
1847 _operands_index_map_count = 0;
1848 int operands_index_map_len = ConstantPool::operand_array_length(scratch_cp->operands());
1849 _operands_index_map_p = new intArray(operands_index_map_len, operands_index_map_len, -1);
1850
1851 // reference to the cp holder is needed for copy_operands()
1852 merge_cp->set_pool_holder(scratch_class);
1853 bool result = merge_constant_pools(old_cp, scratch_cp, &merge_cp,
1854 &merge_cp_length, THREAD);
1855 merge_cp->set_pool_holder(NULL);
1856
1857 if (!result) {
1858 // The merge can fail due to memory allocation failure or due
1859 // to robustness checks.
1860 return JVMTI_ERROR_INTERNAL;
1861 }
1862
1863 // Set dynamic constants attribute from the original CP.
1864 if (old_cp->has_dynamic_constant()) {
1865 scratch_cp->set_has_dynamic_constant();
1866 }
1867 // Copy attributes from scratch_cp to merge_cp
1868 merge_cp->copy_fields(scratch_cp());
1869
1870 log_info(redefine, class, constantpool)("merge_cp_len=%d, index_map_len=%d", merge_cp_length, _index_map_count);
1871
1872 if (_index_map_count == 0) {
1873 // there is nothing to map between the new and merged constant pools
1874
1875 if (old_cp->length() == scratch_cp->length()) {
1876 // The old and new constant pools are the same length and the
1877 // index map is empty. This means that the three constant pools
1878 // are equivalent (but not the same). Unfortunately, the new
1879 // constant pool has not gone through link resolution nor have
1880 // the new class bytecodes gone through constant pool cache
1881 // rewriting so we can't use the old constant pool with the new
1882 // class.
1883
1884 // toss the merged constant pool at return
1885 } else if (old_cp->length() < scratch_cp->length()) {
1886 // The old constant pool has fewer entries than the new constant
1887 // pool and the index map is empty. This means the new constant
1888 // pool is a superset of the old constant pool. However, the old
1889 // class bytecodes have already gone through constant pool cache
1890 // rewriting so we can't use the new constant pool with the old
1891 // class.
1892
1893 // toss the merged constant pool at return
1894 } else {
1895 // The old constant pool has more entries than the new constant
1896 // pool and the index map is empty. This means that both the old
1897 // and merged constant pools are supersets of the new constant
1898 // pool.
1899
1900 // Replace the new constant pool with a shrunken copy of the
1901 // merged constant pool
1902 set_new_constant_pool(loader_data, scratch_class, merge_cp, merge_cp_length,
1903 CHECK_(JVMTI_ERROR_OUT_OF_MEMORY));
1904 // The new constant pool replaces scratch_cp so have cleaner clean it up.
1905 // It can't be cleaned up while there are handles to it.
1906 cp_cleaner.add_scratch_cp(scratch_cp());
1907 }
1908 } else {
1909 if (log_is_enabled(Trace, redefine, class, constantpool)) {
1910 // don't want to loop unless we are tracing
1911 int count = 0;
1912 for (int i = 1; i < _index_map_p->length(); i++) {
1913 int value = _index_map_p->at(i);
1914
1915 if (value != -1) {
1916 log_trace(redefine, class, constantpool)("index_map[%d]: old=%d new=%d", count, i, value);
1917 count++;
1918 }
1919 }
1920 }
1921
1922 // We have entries mapped between the new and merged constant pools
1923 // so we have to rewrite some constant pool references.
1924 if (!rewrite_cp_refs(scratch_class)) {
1925 return JVMTI_ERROR_INTERNAL;
1926 }
1927
1928 // Replace the new constant pool with a shrunken copy of the
1929 // merged constant pool so now the rewritten bytecodes have
1930 // valid references; the previous new constant pool will get
1931 // GCed.
1932 set_new_constant_pool(loader_data, scratch_class, merge_cp, merge_cp_length,
1933 CHECK_(JVMTI_ERROR_OUT_OF_MEMORY));
1934 // The new constant pool replaces scratch_cp so have cleaner clean it up.
1935 // It can't be cleaned up while there are handles to it.
1936 cp_cleaner.add_scratch_cp(scratch_cp());
1937 }
1938
1939 return JVMTI_ERROR_NONE;
1940 } // end merge_cp_and_rewrite()
1941
1942
1943 // Rewrite constant pool references in klass scratch_class.
1944 bool VM_RedefineClasses::rewrite_cp_refs(InstanceKlass* scratch_class) {
1945
1946 // rewrite constant pool references in the nest attributes:
1947 if (!rewrite_cp_refs_in_nest_attributes(scratch_class)) {
1948 // propagate failure back to caller
1949 return false;
1950 }
1951
1952 // rewrite constant pool references in the Record attribute:
1953 if (!rewrite_cp_refs_in_record_attribute(scratch_class)) {
1954 // propagate failure back to caller
1955 return false;
1956 }
1957
1958 // rewrite constant pool references in the PermittedSubclasses attribute:
1959 if (!rewrite_cp_refs_in_permitted_subclasses_attribute(scratch_class)) {
1960 // propagate failure back to caller
1961 return false;
1962 }
1963
1964 // rewrite constant pool references in the methods:
1965 if (!rewrite_cp_refs_in_methods(scratch_class)) {
1966 // propagate failure back to caller
1967 return false;
1968 }
1969
1970 // rewrite constant pool references in the class_annotations:
1971 if (!rewrite_cp_refs_in_class_annotations(scratch_class)) {
1972 // propagate failure back to caller
1973 return false;
1974 }
1975
1976 // rewrite constant pool references in the fields_annotations:
1977 if (!rewrite_cp_refs_in_fields_annotations(scratch_class)) {
1978 // propagate failure back to caller
1979 return false;
1980 }
1981
1982 // rewrite constant pool references in the methods_annotations:
1983 if (!rewrite_cp_refs_in_methods_annotations(scratch_class)) {
1984 // propagate failure back to caller
1985 return false;
1986 }
1987
1988 // rewrite constant pool references in the methods_parameter_annotations:
1989 if (!rewrite_cp_refs_in_methods_parameter_annotations(scratch_class)) {
1990 // propagate failure back to caller
1991 return false;
1992 }
1993
1994 // rewrite constant pool references in the methods_default_annotations:
1995 if (!rewrite_cp_refs_in_methods_default_annotations(scratch_class)) {
1996 // propagate failure back to caller
1997 return false;
1998 }
1999
2000 // rewrite constant pool references in the class_type_annotations:
2001 if (!rewrite_cp_refs_in_class_type_annotations(scratch_class)) {
2002 // propagate failure back to caller
2003 return false;
2004 }
2005
2006 // rewrite constant pool references in the fields_type_annotations:
2007 if (!rewrite_cp_refs_in_fields_type_annotations(scratch_class)) {
2008 // propagate failure back to caller
2009 return false;
2010 }
2011
2012 // rewrite constant pool references in the methods_type_annotations:
2013 if (!rewrite_cp_refs_in_methods_type_annotations(scratch_class)) {
2014 // propagate failure back to caller
2015 return false;
2016 }
2017
2018 // There can be type annotations in the Code part of a method_info attribute.
2019 // These annotations are not accessible, even by reflection.
2020 // Currently they are not even parsed by the ClassFileParser.
2021 // If runtime access is added they will also need to be rewritten.
2022
2023 // rewrite source file name index:
2024 u2 source_file_name_idx = scratch_class->source_file_name_index();
2025 if (source_file_name_idx != 0) {
2026 u2 new_source_file_name_idx = find_new_index(source_file_name_idx);
2027 if (new_source_file_name_idx != 0) {
2028 scratch_class->set_source_file_name_index(new_source_file_name_idx);
2029 }
2030 }
2031
2032 // rewrite class generic signature index:
2033 u2 generic_signature_index = scratch_class->generic_signature_index();
2034 if (generic_signature_index != 0) {
2035 u2 new_generic_signature_index = find_new_index(generic_signature_index);
2036 if (new_generic_signature_index != 0) {
2037 scratch_class->set_generic_signature_index(new_generic_signature_index);
2038 }
2039 }
2040
2041 return true;
2042 } // end rewrite_cp_refs()
2043
2044 // Rewrite constant pool references in the NestHost and NestMembers attributes.
2045 bool VM_RedefineClasses::rewrite_cp_refs_in_nest_attributes(
2046 InstanceKlass* scratch_class) {
2047
2048 u2 cp_index = scratch_class->nest_host_index();
2049 if (cp_index != 0) {
2050 scratch_class->set_nest_host_index(find_new_index(cp_index));
2051 }
2052 Array<u2>* nest_members = scratch_class->nest_members();
2053 for (int i = 0; i < nest_members->length(); i++) {
2054 u2 cp_index = nest_members->at(i);
2055 nest_members->at_put(i, find_new_index(cp_index));
2056 }
2057 return true;
2058 }
2059
2060 // Rewrite constant pool references in the Record attribute.
2061 bool VM_RedefineClasses::rewrite_cp_refs_in_record_attribute(InstanceKlass* scratch_class) {
2062 Array<RecordComponent*>* components = scratch_class->record_components();
2063 if (components != NULL) {
2064 for (int i = 0; i < components->length(); i++) {
2065 RecordComponent* component = components->at(i);
2066 u2 cp_index = component->name_index();
2067 component->set_name_index(find_new_index(cp_index));
2068 cp_index = component->descriptor_index();
2069 component->set_descriptor_index(find_new_index(cp_index));
2070 cp_index = component->generic_signature_index();
2071 if (cp_index != 0) {
2072 component->set_generic_signature_index(find_new_index(cp_index));
2073 }
2074
2075 AnnotationArray* annotations = component->annotations();
2076 if (annotations != NULL && annotations->length() != 0) {
2077 int byte_i = 0; // byte index into annotations
2078 if (!rewrite_cp_refs_in_annotations_typeArray(annotations, byte_i)) {
2079 log_debug(redefine, class, annotation)("bad record_component_annotations at %d", i);
2080 // propagate failure back to caller
2081 return false;
2082 }
2083 }
2084
2085 AnnotationArray* type_annotations = component->type_annotations();
2086 if (type_annotations != NULL && type_annotations->length() != 0) {
2087 int byte_i = 0; // byte index into annotations
2088 if (!rewrite_cp_refs_in_annotations_typeArray(type_annotations, byte_i)) {
2089 log_debug(redefine, class, annotation)("bad record_component_type_annotations at %d", i);
2090 // propagate failure back to caller
2091 return false;
2092 }
2093 }
2094 }
2095 }
2096 return true;
2097 }
2098
2099 // Rewrite constant pool references in the PermittedSubclasses attribute.
2100 bool VM_RedefineClasses::rewrite_cp_refs_in_permitted_subclasses_attribute(
2101 InstanceKlass* scratch_class) {
2102
2103 Array<u2>* permitted_subclasses = scratch_class->permitted_subclasses();
2104 assert(permitted_subclasses != NULL, "unexpected null permitted_subclasses");
2105 for (int i = 0; i < permitted_subclasses->length(); i++) {
2106 u2 cp_index = permitted_subclasses->at(i);
2107 permitted_subclasses->at_put(i, find_new_index(cp_index));
2108 }
2109 return true;
2110 }
2111
2112 // Rewrite constant pool references in the methods.
2113 bool VM_RedefineClasses::rewrite_cp_refs_in_methods(InstanceKlass* scratch_class) {
2114
2115 Array<Method*>* methods = scratch_class->methods();
2116
2117 if (methods == NULL || methods->length() == 0) {
2118 // no methods so nothing to do
2119 return true;
2120 }
2121
2122 JavaThread* THREAD = JavaThread::current(); // For exception macros.
2123 ExceptionMark em(THREAD);
2124
2125 // rewrite constant pool references in the methods:
2126 for (int i = methods->length() - 1; i >= 0; i--) {
2127 methodHandle method(THREAD, methods->at(i));
2128 methodHandle new_method;
2129 rewrite_cp_refs_in_method(method, &new_method, THREAD);
2130 if (!new_method.is_null()) {
2131 // the method has been replaced so save the new method version
2132 // even in the case of an exception. original method is on the
2133 // deallocation list.
2134 methods->at_put(i, new_method());
2135 }
2136 if (HAS_PENDING_EXCEPTION) {
2137 Symbol* ex_name = PENDING_EXCEPTION->klass()->name();
2138 log_info(redefine, class, load, exceptions)("rewrite_cp_refs_in_method exception: '%s'", ex_name->as_C_string());
2139 // Need to clear pending exception here as the super caller sets
2140 // the JVMTI_ERROR_INTERNAL if the returned value is false.
2141 CLEAR_PENDING_EXCEPTION;
2142 return false;
2143 }
2144 }
2145
2146 return true;
2147 }
2148
2149
2150 // Rewrite constant pool references in the specific method. This code
2151 // was adapted from Rewriter::rewrite_method().
2152 void VM_RedefineClasses::rewrite_cp_refs_in_method(methodHandle method,
2153 methodHandle *new_method_p, TRAPS) {
2154
2155 *new_method_p = methodHandle(); // default is no new method
2156
2157 // We cache a pointer to the bytecodes here in code_base. If GC
2158 // moves the Method*, then the bytecodes will also move which
2159 // will likely cause a crash. We create a NoSafepointVerifier
2160 // object to detect whether we pass a possible safepoint in this
2161 // code block.
2162 NoSafepointVerifier nsv;
2163
2164 // Bytecodes and their length
2165 address code_base = method->code_base();
2166 int code_length = method->code_size();
2167
2168 int bc_length;
2169 for (int bci = 0; bci < code_length; bci += bc_length) {
2170 address bcp = code_base + bci;
2171 Bytecodes::Code c = (Bytecodes::Code)(*bcp);
2172
2173 bc_length = Bytecodes::length_for(c);
2174 if (bc_length == 0) {
2175 // More complicated bytecodes report a length of zero so
2176 // we have to try again a slightly different way.
2177 bc_length = Bytecodes::length_at(method(), bcp);
2178 }
2179
2180 assert(bc_length != 0, "impossible bytecode length");
2181
2182 switch (c) {
2183 case Bytecodes::_ldc:
2184 {
2185 int cp_index = *(bcp + 1);
2186 int new_index = find_new_index(cp_index);
2187
2188 if (StressLdcRewrite && new_index == 0) {
2189 // If we are stressing ldc -> ldc_w rewriting, then we
2190 // always need a new_index value.
2191 new_index = cp_index;
2192 }
2193 if (new_index != 0) {
2194 // the original index is mapped so we have more work to do
2195 if (!StressLdcRewrite && new_index <= max_jubyte) {
2196 // The new value can still use ldc instead of ldc_w
2197 // unless we are trying to stress ldc -> ldc_w rewriting
2198 log_trace(redefine, class, constantpool)
2199 ("%s@" INTPTR_FORMAT " old=%d, new=%d", Bytecodes::name(c), p2i(bcp), cp_index, new_index);
2200 *(bcp + 1) = new_index;
2201 } else {
2202 log_trace(redefine, class, constantpool)
2203 ("%s->ldc_w@" INTPTR_FORMAT " old=%d, new=%d", Bytecodes::name(c), p2i(bcp), cp_index, new_index);
2204 // the new value needs ldc_w instead of ldc
2205 u_char inst_buffer[4]; // max instruction size is 4 bytes
2206 bcp = (address)inst_buffer;
2207 // construct new instruction sequence
2208 *bcp = Bytecodes::_ldc_w;
2209 bcp++;
2210 // Rewriter::rewrite_method() does not rewrite ldc -> ldc_w.
2211 // See comment below for difference between put_Java_u2()
2212 // and put_native_u2().
2213 Bytes::put_Java_u2(bcp, new_index);
2214
2215 Relocator rc(method, NULL /* no RelocatorListener needed */);
2216 methodHandle m;
2217 {
2218 PauseNoSafepointVerifier pnsv(&nsv);
2219
2220 // ldc is 2 bytes and ldc_w is 3 bytes
2221 m = rc.insert_space_at(bci, 3, inst_buffer, CHECK);
2222 }
2223
2224 // return the new method so that the caller can update
2225 // the containing class
2226 *new_method_p = method = m;
2227 // switch our bytecode processing loop from the old method
2228 // to the new method
2229 code_base = method->code_base();
2230 code_length = method->code_size();
2231 bcp = code_base + bci;
2232 c = (Bytecodes::Code)(*bcp);
2233 bc_length = Bytecodes::length_for(c);
2234 assert(bc_length != 0, "sanity check");
2235 } // end we need ldc_w instead of ldc
2236 } // end if there is a mapped index
2237 } break;
2238
2239 // these bytecodes have a two-byte constant pool index
2240 case Bytecodes::_anewarray : // fall through
2241 case Bytecodes::_checkcast : // fall through
2242 case Bytecodes::_getfield : // fall through
2243 case Bytecodes::_getstatic : // fall through
2244 case Bytecodes::_instanceof : // fall through
2245 case Bytecodes::_invokedynamic : // fall through
2246 case Bytecodes::_invokeinterface: // fall through
2247 case Bytecodes::_invokespecial : // fall through
2248 case Bytecodes::_invokestatic : // fall through
2249 case Bytecodes::_invokevirtual : // fall through
2250 case Bytecodes::_ldc_w : // fall through
2251 case Bytecodes::_ldc2_w : // fall through
2252 case Bytecodes::_multianewarray : // fall through
2253 case Bytecodes::_new : // fall through
2254 case Bytecodes::_putfield : // fall through
2255 case Bytecodes::_putstatic :
2256 {
2257 address p = bcp + 1;
2258 int cp_index = Bytes::get_Java_u2(p);
2259 int new_index = find_new_index(cp_index);
2260 if (new_index != 0) {
2261 // the original index is mapped so update w/ new value
2262 log_trace(redefine, class, constantpool)
2263 ("%s@" INTPTR_FORMAT " old=%d, new=%d", Bytecodes::name(c),p2i(bcp), cp_index, new_index);
2264 // Rewriter::rewrite_method() uses put_native_u2() in this
2265 // situation because it is reusing the constant pool index
2266 // location for a native index into the ConstantPoolCache.
2267 // Since we are updating the constant pool index prior to
2268 // verification and ConstantPoolCache initialization, we
2269 // need to keep the new index in Java byte order.
2270 Bytes::put_Java_u2(p, new_index);
2271 }
2272 } break;
2273 default:
2274 break;
2275 }
2276 } // end for each bytecode
2277
2278 // We also need to rewrite the parameter name indexes, if there is
2279 // method parameter data present
2280 if(method->has_method_parameters()) {
2281 const int len = method->method_parameters_length();
2282 MethodParametersElement* elem = method->method_parameters_start();
2283
2284 for (int i = 0; i < len; i++) {
2285 const u2 cp_index = elem[i].name_cp_index;
2286 const u2 new_cp_index = find_new_index(cp_index);
2287 if (new_cp_index != 0) {
2288 elem[i].name_cp_index = new_cp_index;
2289 }
2290 }
2291 }
2292 } // end rewrite_cp_refs_in_method()
2293
2294
2295 // Rewrite constant pool references in the class_annotations field.
2296 bool VM_RedefineClasses::rewrite_cp_refs_in_class_annotations(InstanceKlass* scratch_class) {
2297
2298 AnnotationArray* class_annotations = scratch_class->class_annotations();
2299 if (class_annotations == NULL || class_annotations->length() == 0) {
2300 // no class_annotations so nothing to do
2301 return true;
2302 }
2303
2304 log_debug(redefine, class, annotation)("class_annotations length=%d", class_annotations->length());
2305
2306 int byte_i = 0; // byte index into class_annotations
2307 return rewrite_cp_refs_in_annotations_typeArray(class_annotations, byte_i);
2308 }
2309
2310
2311 // Rewrite constant pool references in an annotations typeArray. This
2312 // "structure" is adapted from the RuntimeVisibleAnnotations_attribute
2313 // that is described in section 4.8.15 of the 2nd-edition of the VM spec:
2314 //
2315 // annotations_typeArray {
2316 // u2 num_annotations;
2317 // annotation annotations[num_annotations];
2318 // }
2319 //
2320 bool VM_RedefineClasses::rewrite_cp_refs_in_annotations_typeArray(
2321 AnnotationArray* annotations_typeArray, int &byte_i_ref) {
2322
2323 if ((byte_i_ref + 2) > annotations_typeArray->length()) {
2324 // not enough room for num_annotations field
2325 log_debug(redefine, class, annotation)("length() is too small for num_annotations field");
2326 return false;
2327 }
2328
2329 u2 num_annotations = Bytes::get_Java_u2((address)
2330 annotations_typeArray->adr_at(byte_i_ref));
2331 byte_i_ref += 2;
2332
2333 log_debug(redefine, class, annotation)("num_annotations=%d", num_annotations);
2334
2335 int calc_num_annotations = 0;
2336 for (; calc_num_annotations < num_annotations; calc_num_annotations++) {
2337 if (!rewrite_cp_refs_in_annotation_struct(annotations_typeArray, byte_i_ref)) {
2338 log_debug(redefine, class, annotation)("bad annotation_struct at %d", calc_num_annotations);
2339 // propagate failure back to caller
2340 return false;
2341 }
2342 }
2343 assert(num_annotations == calc_num_annotations, "sanity check");
2344
2345 return true;
2346 } // end rewrite_cp_refs_in_annotations_typeArray()
2347
2348
2349 // Rewrite constant pool references in the annotation struct portion of
2350 // an annotations_typeArray. This "structure" is from section 4.8.15 of
2351 // the 2nd-edition of the VM spec:
2352 //
2353 // struct annotation {
2354 // u2 type_index;
2355 // u2 num_element_value_pairs;
2356 // {
2357 // u2 element_name_index;
2358 // element_value value;
2359 // } element_value_pairs[num_element_value_pairs];
2360 // }
2361 //
2362 bool VM_RedefineClasses::rewrite_cp_refs_in_annotation_struct(
2363 AnnotationArray* annotations_typeArray, int &byte_i_ref) {
2364 if ((byte_i_ref + 2 + 2) > annotations_typeArray->length()) {
2365 // not enough room for smallest annotation_struct
2366 log_debug(redefine, class, annotation)("length() is too small for annotation_struct");
2367 return false;
2368 }
2369
2370 u2 type_index = rewrite_cp_ref_in_annotation_data(annotations_typeArray,
2371 byte_i_ref, "type_index");
2372
2373 u2 num_element_value_pairs = Bytes::get_Java_u2((address)
2374 annotations_typeArray->adr_at(byte_i_ref));
2375 byte_i_ref += 2;
2376
2377 log_debug(redefine, class, annotation)
2378 ("type_index=%d num_element_value_pairs=%d", type_index, num_element_value_pairs);
2379
2380 int calc_num_element_value_pairs = 0;
2381 for (; calc_num_element_value_pairs < num_element_value_pairs;
2382 calc_num_element_value_pairs++) {
2383 if ((byte_i_ref + 2) > annotations_typeArray->length()) {
2384 // not enough room for another element_name_index, let alone
2385 // the rest of another component
2386 log_debug(redefine, class, annotation)("length() is too small for element_name_index");
2387 return false;
2388 }
2389
2390 u2 element_name_index = rewrite_cp_ref_in_annotation_data(
2391 annotations_typeArray, byte_i_ref,
2392 "element_name_index");
2393
2394 log_debug(redefine, class, annotation)("element_name_index=%d", element_name_index);
2395
2396 if (!rewrite_cp_refs_in_element_value(annotations_typeArray, byte_i_ref)) {
2397 log_debug(redefine, class, annotation)("bad element_value at %d", calc_num_element_value_pairs);
2398 // propagate failure back to caller
2399 return false;
2400 }
2401 } // end for each component
2402 assert(num_element_value_pairs == calc_num_element_value_pairs,
2403 "sanity check");
2404
2405 return true;
2406 } // end rewrite_cp_refs_in_annotation_struct()
2407
2408
2409 // Rewrite a constant pool reference at the current position in
2410 // annotations_typeArray if needed. Returns the original constant
2411 // pool reference if a rewrite was not needed or the new constant
2412 // pool reference if a rewrite was needed.
2413 u2 VM_RedefineClasses::rewrite_cp_ref_in_annotation_data(
2414 AnnotationArray* annotations_typeArray, int &byte_i_ref,
2415 const char * trace_mesg) {
2416
2417 address cp_index_addr = (address)
2418 annotations_typeArray->adr_at(byte_i_ref);
2419 u2 old_cp_index = Bytes::get_Java_u2(cp_index_addr);
2420 u2 new_cp_index = find_new_index(old_cp_index);
2421 if (new_cp_index != 0) {
2422 log_debug(redefine, class, annotation)("mapped old %s=%d", trace_mesg, old_cp_index);
2423 Bytes::put_Java_u2(cp_index_addr, new_cp_index);
2424 old_cp_index = new_cp_index;
2425 }
2426 byte_i_ref += 2;
2427 return old_cp_index;
2428 }
2429
2430
2431 // Rewrite constant pool references in the element_value portion of an
2432 // annotations_typeArray. This "structure" is from section 4.8.15.1 of
2433 // the 2nd-edition of the VM spec:
2434 //
2435 // struct element_value {
2436 // u1 tag;
2437 // union {
2438 // u2 const_value_index;
2439 // {
2440 // u2 type_name_index;
2441 // u2 const_name_index;
2442 // } enum_const_value;
2443 // u2 class_info_index;
2444 // annotation annotation_value;
2445 // struct {
2446 // u2 num_values;
2447 // element_value values[num_values];
2448 // } array_value;
2449 // } value;
2450 // }
2451 //
2452 bool VM_RedefineClasses::rewrite_cp_refs_in_element_value(
2453 AnnotationArray* annotations_typeArray, int &byte_i_ref) {
2454
2455 if ((byte_i_ref + 1) > annotations_typeArray->length()) {
2456 // not enough room for a tag let alone the rest of an element_value
2457 log_debug(redefine, class, annotation)("length() is too small for a tag");
2458 return false;
2459 }
2460
2461 u1 tag = annotations_typeArray->at(byte_i_ref);
2462 byte_i_ref++;
2463 log_debug(redefine, class, annotation)("tag='%c'", tag);
2464
2465 switch (tag) {
2466 // These BaseType tag values are from Table 4.2 in VM spec:
2467 case JVM_SIGNATURE_BYTE:
2468 case JVM_SIGNATURE_CHAR:
2469 case JVM_SIGNATURE_DOUBLE:
2470 case JVM_SIGNATURE_FLOAT:
2471 case JVM_SIGNATURE_INT:
2472 case JVM_SIGNATURE_LONG:
2473 case JVM_SIGNATURE_SHORT:
2474 case JVM_SIGNATURE_BOOLEAN:
2475
2476 // The remaining tag values are from Table 4.8 in the 2nd-edition of
2477 // the VM spec:
2478 case 's':
2479 {
2480 // For the above tag values (including the BaseType values),
2481 // value.const_value_index is right union field.
2482
2483 if ((byte_i_ref + 2) > annotations_typeArray->length()) {
2484 // not enough room for a const_value_index
2485 log_debug(redefine, class, annotation)("length() is too small for a const_value_index");
2486 return false;
2487 }
2488
2489 u2 const_value_index = rewrite_cp_ref_in_annotation_data(
2490 annotations_typeArray, byte_i_ref,
2491 "const_value_index");
2492
2493 log_debug(redefine, class, annotation)("const_value_index=%d", const_value_index);
2494 } break;
2495
2496 case 'e':
2497 {
2498 // for the above tag value, value.enum_const_value is right union field
2499
2500 if ((byte_i_ref + 4) > annotations_typeArray->length()) {
2501 // not enough room for a enum_const_value
2502 log_debug(redefine, class, annotation)("length() is too small for a enum_const_value");
2503 return false;
2504 }
2505
2506 u2 type_name_index = rewrite_cp_ref_in_annotation_data(
2507 annotations_typeArray, byte_i_ref,
2508 "type_name_index");
2509
2510 u2 const_name_index = rewrite_cp_ref_in_annotation_data(
2511 annotations_typeArray, byte_i_ref,
2512 "const_name_index");
2513
2514 log_debug(redefine, class, annotation)
2515 ("type_name_index=%d const_name_index=%d", type_name_index, const_name_index);
2516 } break;
2517
2518 case 'c':
2519 {
2520 // for the above tag value, value.class_info_index is right union field
2521
2522 if ((byte_i_ref + 2) > annotations_typeArray->length()) {
2523 // not enough room for a class_info_index
2524 log_debug(redefine, class, annotation)("length() is too small for a class_info_index");
2525 return false;
2526 }
2527
2528 u2 class_info_index = rewrite_cp_ref_in_annotation_data(
2529 annotations_typeArray, byte_i_ref,
2530 "class_info_index");
2531
2532 log_debug(redefine, class, annotation)("class_info_index=%d", class_info_index);
2533 } break;
2534
2535 case '@':
2536 // For the above tag value, value.attr_value is the right union
2537 // field. This is a nested annotation.
2538 if (!rewrite_cp_refs_in_annotation_struct(annotations_typeArray, byte_i_ref)) {
2539 // propagate failure back to caller
2540 return false;
2541 }
2542 break;
2543
2544 case JVM_SIGNATURE_ARRAY:
2545 {
2546 if ((byte_i_ref + 2) > annotations_typeArray->length()) {
2547 // not enough room for a num_values field
2548 log_debug(redefine, class, annotation)("length() is too small for a num_values field");
2549 return false;
2550 }
2551
2552 // For the above tag value, value.array_value is the right union
2553 // field. This is an array of nested element_value.
2554 u2 num_values = Bytes::get_Java_u2((address)
2555 annotations_typeArray->adr_at(byte_i_ref));
2556 byte_i_ref += 2;
2557 log_debug(redefine, class, annotation)("num_values=%d", num_values);
2558
2559 int calc_num_values = 0;
2560 for (; calc_num_values < num_values; calc_num_values++) {
2561 if (!rewrite_cp_refs_in_element_value(annotations_typeArray, byte_i_ref)) {
2562 log_debug(redefine, class, annotation)("bad nested element_value at %d", calc_num_values);
2563 // propagate failure back to caller
2564 return false;
2565 }
2566 }
2567 assert(num_values == calc_num_values, "sanity check");
2568 } break;
2569
2570 default:
2571 log_debug(redefine, class, annotation)("bad tag=0x%x", tag);
2572 return false;
2573 } // end decode tag field
2574
2575 return true;
2576 } // end rewrite_cp_refs_in_element_value()
2577
2578
2579 // Rewrite constant pool references in a fields_annotations field.
2580 bool VM_RedefineClasses::rewrite_cp_refs_in_fields_annotations(
2581 InstanceKlass* scratch_class) {
2582
2583 Array<AnnotationArray*>* fields_annotations = scratch_class->fields_annotations();
2584
2585 if (fields_annotations == NULL || fields_annotations->length() == 0) {
2586 // no fields_annotations so nothing to do
2587 return true;
2588 }
2589
2590 log_debug(redefine, class, annotation)("fields_annotations length=%d", fields_annotations->length());
2591
2592 for (int i = 0; i < fields_annotations->length(); i++) {
2593 AnnotationArray* field_annotations = fields_annotations->at(i);
2594 if (field_annotations == NULL || field_annotations->length() == 0) {
2595 // this field does not have any annotations so skip it
2596 continue;
2597 }
2598
2599 int byte_i = 0; // byte index into field_annotations
2600 if (!rewrite_cp_refs_in_annotations_typeArray(field_annotations, byte_i)) {
2601 log_debug(redefine, class, annotation)("bad field_annotations at %d", i);
2602 // propagate failure back to caller
2603 return false;
2604 }
2605 }
2606
2607 return true;
2608 } // end rewrite_cp_refs_in_fields_annotations()
2609
2610
2611 // Rewrite constant pool references in a methods_annotations field.
2612 bool VM_RedefineClasses::rewrite_cp_refs_in_methods_annotations(
2613 InstanceKlass* scratch_class) {
2614
2615 for (int i = 0; i < scratch_class->methods()->length(); i++) {
2616 Method* m = scratch_class->methods()->at(i);
2617 AnnotationArray* method_annotations = m->constMethod()->method_annotations();
2618
2619 if (method_annotations == NULL || method_annotations->length() == 0) {
2620 // this method does not have any annotations so skip it
2621 continue;
2622 }
2623
2624 int byte_i = 0; // byte index into method_annotations
2625 if (!rewrite_cp_refs_in_annotations_typeArray(method_annotations, byte_i)) {
2626 log_debug(redefine, class, annotation)("bad method_annotations at %d", i);
2627 // propagate failure back to caller
2628 return false;
2629 }
2630 }
2631
2632 return true;
2633 } // end rewrite_cp_refs_in_methods_annotations()
2634
2635
2636 // Rewrite constant pool references in a methods_parameter_annotations
2637 // field. This "structure" is adapted from the
2638 // RuntimeVisibleParameterAnnotations_attribute described in section
2639 // 4.8.17 of the 2nd-edition of the VM spec:
2640 //
2641 // methods_parameter_annotations_typeArray {
2642 // u1 num_parameters;
2643 // {
2644 // u2 num_annotations;
2645 // annotation annotations[num_annotations];
2646 // } parameter_annotations[num_parameters];
2647 // }
2648 //
2649 bool VM_RedefineClasses::rewrite_cp_refs_in_methods_parameter_annotations(
2650 InstanceKlass* scratch_class) {
2651
2652 for (int i = 0; i < scratch_class->methods()->length(); i++) {
2653 Method* m = scratch_class->methods()->at(i);
2654 AnnotationArray* method_parameter_annotations = m->constMethod()->parameter_annotations();
2655 if (method_parameter_annotations == NULL
2656 || method_parameter_annotations->length() == 0) {
2657 // this method does not have any parameter annotations so skip it
2658 continue;
2659 }
2660
2661 if (method_parameter_annotations->length() < 1) {
2662 // not enough room for a num_parameters field
2663 log_debug(redefine, class, annotation)("length() is too small for a num_parameters field at %d", i);
2664 return false;
2665 }
2666
2667 int byte_i = 0; // byte index into method_parameter_annotations
2668
2669 u1 num_parameters = method_parameter_annotations->at(byte_i);
2670 byte_i++;
2671
2672 log_debug(redefine, class, annotation)("num_parameters=%d", num_parameters);
2673
2674 int calc_num_parameters = 0;
2675 for (; calc_num_parameters < num_parameters; calc_num_parameters++) {
2676 if (!rewrite_cp_refs_in_annotations_typeArray(method_parameter_annotations, byte_i)) {
2677 log_debug(redefine, class, annotation)("bad method_parameter_annotations at %d", calc_num_parameters);
2678 // propagate failure back to caller
2679 return false;
2680 }
2681 }
2682 assert(num_parameters == calc_num_parameters, "sanity check");
2683 }
2684
2685 return true;
2686 } // end rewrite_cp_refs_in_methods_parameter_annotations()
2687
2688
2689 // Rewrite constant pool references in a methods_default_annotations
2690 // field. This "structure" is adapted from the AnnotationDefault_attribute
2691 // that is described in section 4.8.19 of the 2nd-edition of the VM spec:
2692 //
2693 // methods_default_annotations_typeArray {
2694 // element_value default_value;
2695 // }
2696 //
2697 bool VM_RedefineClasses::rewrite_cp_refs_in_methods_default_annotations(
2698 InstanceKlass* scratch_class) {
2699
2700 for (int i = 0; i < scratch_class->methods()->length(); i++) {
2701 Method* m = scratch_class->methods()->at(i);
2702 AnnotationArray* method_default_annotations = m->constMethod()->default_annotations();
2703 if (method_default_annotations == NULL
2704 || method_default_annotations->length() == 0) {
2705 // this method does not have any default annotations so skip it
2706 continue;
2707 }
2708
2709 int byte_i = 0; // byte index into method_default_annotations
2710
2711 if (!rewrite_cp_refs_in_element_value(
2712 method_default_annotations, byte_i)) {
2713 log_debug(redefine, class, annotation)("bad default element_value at %d", i);
2714 // propagate failure back to caller
2715 return false;
2716 }
2717 }
2718
2719 return true;
2720 } // end rewrite_cp_refs_in_methods_default_annotations()
2721
2722
2723 // Rewrite constant pool references in a class_type_annotations field.
2724 bool VM_RedefineClasses::rewrite_cp_refs_in_class_type_annotations(
2725 InstanceKlass* scratch_class) {
2726
2727 AnnotationArray* class_type_annotations = scratch_class->class_type_annotations();
2728 if (class_type_annotations == NULL || class_type_annotations->length() == 0) {
2729 // no class_type_annotations so nothing to do
2730 return true;
2731 }
2732
2733 log_debug(redefine, class, annotation)("class_type_annotations length=%d", class_type_annotations->length());
2734
2735 int byte_i = 0; // byte index into class_type_annotations
2736 return rewrite_cp_refs_in_type_annotations_typeArray(class_type_annotations,
2737 byte_i, "ClassFile");
2738 } // end rewrite_cp_refs_in_class_type_annotations()
2739
2740
2741 // Rewrite constant pool references in a fields_type_annotations field.
2742 bool VM_RedefineClasses::rewrite_cp_refs_in_fields_type_annotations(InstanceKlass* scratch_class) {
2743
2744 Array<AnnotationArray*>* fields_type_annotations = scratch_class->fields_type_annotations();
2745 if (fields_type_annotations == NULL || fields_type_annotations->length() == 0) {
2746 // no fields_type_annotations so nothing to do
2747 return true;
2748 }
2749
2750 log_debug(redefine, class, annotation)("fields_type_annotations length=%d", fields_type_annotations->length());
2751
2752 for (int i = 0; i < fields_type_annotations->length(); i++) {
2753 AnnotationArray* field_type_annotations = fields_type_annotations->at(i);
2754 if (field_type_annotations == NULL || field_type_annotations->length() == 0) {
2755 // this field does not have any annotations so skip it
2756 continue;
2757 }
2758
2759 int byte_i = 0; // byte index into field_type_annotations
2760 if (!rewrite_cp_refs_in_type_annotations_typeArray(field_type_annotations,
2761 byte_i, "field_info")) {
2762 log_debug(redefine, class, annotation)("bad field_type_annotations at %d", i);
2763 // propagate failure back to caller
2764 return false;
2765 }
2766 }
2767
2768 return true;
2769 } // end rewrite_cp_refs_in_fields_type_annotations()
2770
2771
2772 // Rewrite constant pool references in a methods_type_annotations field.
2773 bool VM_RedefineClasses::rewrite_cp_refs_in_methods_type_annotations(
2774 InstanceKlass* scratch_class) {
2775
2776 for (int i = 0; i < scratch_class->methods()->length(); i++) {
2777 Method* m = scratch_class->methods()->at(i);
2778 AnnotationArray* method_type_annotations = m->constMethod()->type_annotations();
2779
2780 if (method_type_annotations == NULL || method_type_annotations->length() == 0) {
2781 // this method does not have any annotations so skip it
2782 continue;
2783 }
2784
2785 log_debug(redefine, class, annotation)("methods type_annotations length=%d", method_type_annotations->length());
2786
2787 int byte_i = 0; // byte index into method_type_annotations
2788 if (!rewrite_cp_refs_in_type_annotations_typeArray(method_type_annotations,
2789 byte_i, "method_info")) {
2790 log_debug(redefine, class, annotation)("bad method_type_annotations at %d", i);
2791 // propagate failure back to caller
2792 return false;
2793 }
2794 }
2795
2796 return true;
2797 } // end rewrite_cp_refs_in_methods_type_annotations()
2798
2799
2800 // Rewrite constant pool references in a type_annotations
2801 // field. This "structure" is adapted from the
2802 // RuntimeVisibleTypeAnnotations_attribute described in
2803 // section 4.7.20 of the Java SE 8 Edition of the VM spec:
2804 //
2805 // type_annotations_typeArray {
2806 // u2 num_annotations;
2807 // type_annotation annotations[num_annotations];
2808 // }
2809 //
2810 bool VM_RedefineClasses::rewrite_cp_refs_in_type_annotations_typeArray(
2811 AnnotationArray* type_annotations_typeArray, int &byte_i_ref,
2812 const char * location_mesg) {
2813
2814 if ((byte_i_ref + 2) > type_annotations_typeArray->length()) {
2815 // not enough room for num_annotations field
2816 log_debug(redefine, class, annotation)("length() is too small for num_annotations field");
2817 return false;
2818 }
2819
2820 u2 num_annotations = Bytes::get_Java_u2((address)
2821 type_annotations_typeArray->adr_at(byte_i_ref));
2822 byte_i_ref += 2;
2823
2824 log_debug(redefine, class, annotation)("num_type_annotations=%d", num_annotations);
2825
2826 int calc_num_annotations = 0;
2827 for (; calc_num_annotations < num_annotations; calc_num_annotations++) {
2828 if (!rewrite_cp_refs_in_type_annotation_struct(type_annotations_typeArray,
2829 byte_i_ref, location_mesg)) {
2830 log_debug(redefine, class, annotation)("bad type_annotation_struct at %d", calc_num_annotations);
2831 // propagate failure back to caller
2832 return false;
2833 }
2834 }
2835 assert(num_annotations == calc_num_annotations, "sanity check");
2836
2837 if (byte_i_ref != type_annotations_typeArray->length()) {
2838 log_debug(redefine, class, annotation)
2839 ("read wrong amount of bytes at end of processing type_annotations_typeArray (%d of %d bytes were read)",
2840 byte_i_ref, type_annotations_typeArray->length());
2841 return false;
2842 }
2843
2844 return true;
2845 } // end rewrite_cp_refs_in_type_annotations_typeArray()
2846
2847
2848 // Rewrite constant pool references in a type_annotation
2849 // field. This "structure" is adapted from the
2850 // RuntimeVisibleTypeAnnotations_attribute described in
2851 // section 4.7.20 of the Java SE 8 Edition of the VM spec:
2852 //
2853 // type_annotation {
2854 // u1 target_type;
2855 // union {
2856 // type_parameter_target;
2857 // supertype_target;
2858 // type_parameter_bound_target;
2859 // empty_target;
2860 // method_formal_parameter_target;
2861 // throws_target;
2862 // localvar_target;
2863 // catch_target;
2864 // offset_target;
2865 // type_argument_target;
2866 // } target_info;
2867 // type_path target_path;
2868 // annotation anno;
2869 // }
2870 //
2871 bool VM_RedefineClasses::rewrite_cp_refs_in_type_annotation_struct(
2872 AnnotationArray* type_annotations_typeArray, int &byte_i_ref,
2873 const char * location_mesg) {
2874
2875 if (!skip_type_annotation_target(type_annotations_typeArray,
2876 byte_i_ref, location_mesg)) {
2877 return false;
2878 }
2879
2880 if (!skip_type_annotation_type_path(type_annotations_typeArray, byte_i_ref)) {
2881 return false;
2882 }
2883
2884 if (!rewrite_cp_refs_in_annotation_struct(type_annotations_typeArray, byte_i_ref)) {
2885 return false;
2886 }
2887
2888 return true;
2889 } // end rewrite_cp_refs_in_type_annotation_struct()
2890
2891
2892 // Read, verify and skip over the target_type and target_info part
2893 // so that rewriting can continue in the later parts of the struct.
2894 //
2895 // u1 target_type;
2896 // union {
2897 // type_parameter_target;
2898 // supertype_target;
2899 // type_parameter_bound_target;
2900 // empty_target;
2901 // method_formal_parameter_target;
2902 // throws_target;
2903 // localvar_target;
2904 // catch_target;
2905 // offset_target;
2906 // type_argument_target;
2907 // } target_info;
2908 //
2909 bool VM_RedefineClasses::skip_type_annotation_target(
2910 AnnotationArray* type_annotations_typeArray, int &byte_i_ref,
2911 const char * location_mesg) {
2912
2913 if ((byte_i_ref + 1) > type_annotations_typeArray->length()) {
2914 // not enough room for a target_type let alone the rest of a type_annotation
2915 log_debug(redefine, class, annotation)("length() is too small for a target_type");
2916 return false;
2917 }
2918
2919 u1 target_type = type_annotations_typeArray->at(byte_i_ref);
2920 byte_i_ref += 1;
2921 log_debug(redefine, class, annotation)("target_type=0x%.2x", target_type);
2922 log_debug(redefine, class, annotation)("location=%s", location_mesg);
2923
2924 // Skip over target_info
2925 switch (target_type) {
2926 case 0x00:
2927 // kind: type parameter declaration of generic class or interface
2928 // location: ClassFile
2929 case 0x01:
2930 // kind: type parameter declaration of generic method or constructor
2931 // location: method_info
2932
2933 {
2934 // struct:
2935 // type_parameter_target {
2936 // u1 type_parameter_index;
2937 // }
2938 //
2939 if ((byte_i_ref + 1) > type_annotations_typeArray->length()) {
2940 log_debug(redefine, class, annotation)("length() is too small for a type_parameter_target");
2941 return false;
2942 }
2943
2944 u1 type_parameter_index = type_annotations_typeArray->at(byte_i_ref);
2945 byte_i_ref += 1;
2946
2947 log_debug(redefine, class, annotation)("type_parameter_target: type_parameter_index=%d", type_parameter_index);
2948 } break;
2949
2950 case 0x10:
2951 // kind: type in extends clause of class or interface declaration
2952 // or in implements clause of interface declaration
2953 // location: ClassFile
2954
2955 {
2956 // struct:
2957 // supertype_target {
2958 // u2 supertype_index;
2959 // }
2960 //
2961 if ((byte_i_ref + 2) > type_annotations_typeArray->length()) {
2962 log_debug(redefine, class, annotation)("length() is too small for a supertype_target");
2963 return false;
2964 }
2965
2966 u2 supertype_index = Bytes::get_Java_u2((address)
2967 type_annotations_typeArray->adr_at(byte_i_ref));
2968 byte_i_ref += 2;
2969
2970 log_debug(redefine, class, annotation)("supertype_target: supertype_index=%d", supertype_index);
2971 } break;
2972
2973 case 0x11:
2974 // kind: type in bound of type parameter declaration of generic class or interface
2975 // location: ClassFile
2976 case 0x12:
2977 // kind: type in bound of type parameter declaration of generic method or constructor
2978 // location: method_info
2979
2980 {
2981 // struct:
2982 // type_parameter_bound_target {
2983 // u1 type_parameter_index;
2984 // u1 bound_index;
2985 // }
2986 //
2987 if ((byte_i_ref + 2) > type_annotations_typeArray->length()) {
2988 log_debug(redefine, class, annotation)("length() is too small for a type_parameter_bound_target");
2989 return false;
2990 }
2991
2992 u1 type_parameter_index = type_annotations_typeArray->at(byte_i_ref);
2993 byte_i_ref += 1;
2994 u1 bound_index = type_annotations_typeArray->at(byte_i_ref);
2995 byte_i_ref += 1;
2996
2997 log_debug(redefine, class, annotation)
2998 ("type_parameter_bound_target: type_parameter_index=%d, bound_index=%d", type_parameter_index, bound_index);
2999 } break;
3000
3001 case 0x13:
3002 // kind: type in field declaration
3003 // location: field_info
3004 case 0x14:
3005 // kind: return type of method, or type of newly constructed object
3006 // location: method_info
3007 case 0x15:
3008 // kind: receiver type of method or constructor
3009 // location: method_info
3010
3011 {
3012 // struct:
3013 // empty_target {
3014 // }
3015 //
3016 log_debug(redefine, class, annotation)("empty_target");
3017 } break;
3018
3019 case 0x16:
3020 // kind: type in formal parameter declaration of method, constructor, or lambda expression
3021 // location: method_info
3022
3023 {
3024 // struct:
3025 // formal_parameter_target {
3026 // u1 formal_parameter_index;
3027 // }
3028 //
3029 if ((byte_i_ref + 1) > type_annotations_typeArray->length()) {
3030 log_debug(redefine, class, annotation)("length() is too small for a formal_parameter_target");
3031 return false;
3032 }
3033
3034 u1 formal_parameter_index = type_annotations_typeArray->at(byte_i_ref);
3035 byte_i_ref += 1;
3036
3037 log_debug(redefine, class, annotation)
3038 ("formal_parameter_target: formal_parameter_index=%d", formal_parameter_index);
3039 } break;
3040
3041 case 0x17:
3042 // kind: type in throws clause of method or constructor
3043 // location: method_info
3044
3045 {
3046 // struct:
3047 // throws_target {
3048 // u2 throws_type_index
3049 // }
3050 //
3051 if ((byte_i_ref + 2) > type_annotations_typeArray->length()) {
3052 log_debug(redefine, class, annotation)("length() is too small for a throws_target");
3053 return false;
3054 }
3055
3056 u2 throws_type_index = Bytes::get_Java_u2((address)
3057 type_annotations_typeArray->adr_at(byte_i_ref));
3058 byte_i_ref += 2;
3059
3060 log_debug(redefine, class, annotation)("throws_target: throws_type_index=%d", throws_type_index);
3061 } break;
3062
3063 case 0x40:
3064 // kind: type in local variable declaration
3065 // location: Code
3066 case 0x41:
3067 // kind: type in resource variable declaration
3068 // location: Code
3069
3070 {
3071 // struct:
3072 // localvar_target {
3073 // u2 table_length;
3074 // struct {
3075 // u2 start_pc;
3076 // u2 length;
3077 // u2 index;
3078 // } table[table_length];
3079 // }
3080 //
3081 if ((byte_i_ref + 2) > type_annotations_typeArray->length()) {
3082 // not enough room for a table_length let alone the rest of a localvar_target
3083 log_debug(redefine, class, annotation)("length() is too small for a localvar_target table_length");
3084 return false;
3085 }
3086
3087 u2 table_length = Bytes::get_Java_u2((address)
3088 type_annotations_typeArray->adr_at(byte_i_ref));
3089 byte_i_ref += 2;
3090
3091 log_debug(redefine, class, annotation)("localvar_target: table_length=%d", table_length);
3092
3093 int table_struct_size = 2 + 2 + 2; // 3 u2 variables per table entry
3094 int table_size = table_length * table_struct_size;
3095
3096 if ((byte_i_ref + table_size) > type_annotations_typeArray->length()) {
3097 // not enough room for a table
3098 log_debug(redefine, class, annotation)("length() is too small for a table array of length %d", table_length);
3099 return false;
3100 }
3101
3102 // Skip over table
3103 byte_i_ref += table_size;
3104 } break;
3105
3106 case 0x42:
3107 // kind: type in exception parameter declaration
3108 // location: Code
3109
3110 {
3111 // struct:
3112 // catch_target {
3113 // u2 exception_table_index;
3114 // }
3115 //
3116 if ((byte_i_ref + 2) > type_annotations_typeArray->length()) {
3117 log_debug(redefine, class, annotation)("length() is too small for a catch_target");
3118 return false;
3119 }
3120
3121 u2 exception_table_index = Bytes::get_Java_u2((address)
3122 type_annotations_typeArray->adr_at(byte_i_ref));
3123 byte_i_ref += 2;
3124
3125 log_debug(redefine, class, annotation)("catch_target: exception_table_index=%d", exception_table_index);
3126 } break;
3127
3128 case 0x43:
3129 // kind: type in instanceof expression
3130 // location: Code
3131 case 0x44:
3132 // kind: type in new expression
3133 // location: Code
3134 case 0x45:
3135 // kind: type in method reference expression using ::new
3136 // location: Code
3137 case 0x46:
3138 // kind: type in method reference expression using ::Identifier
3139 // location: Code
3140
3141 {
3142 // struct:
3143 // offset_target {
3144 // u2 offset;
3145 // }
3146 //
3147 if ((byte_i_ref + 2) > type_annotations_typeArray->length()) {
3148 log_debug(redefine, class, annotation)("length() is too small for a offset_target");
3149 return false;
3150 }
3151
3152 u2 offset = Bytes::get_Java_u2((address)
3153 type_annotations_typeArray->adr_at(byte_i_ref));
3154 byte_i_ref += 2;
3155
3156 log_debug(redefine, class, annotation)("offset_target: offset=%d", offset);
3157 } break;
3158
3159 case 0x47:
3160 // kind: type in cast expression
3161 // location: Code
3162 case 0x48:
3163 // kind: type argument for generic constructor in new expression or
3164 // explicit constructor invocation statement
3165 // location: Code
3166 case 0x49:
3167 // kind: type argument for generic method in method invocation expression
3168 // location: Code
3169 case 0x4A:
3170 // kind: type argument for generic constructor in method reference expression using ::new
3171 // location: Code
3172 case 0x4B:
3173 // kind: type argument for generic method in method reference expression using ::Identifier
3174 // location: Code
3175
3176 {
3177 // struct:
3178 // type_argument_target {
3179 // u2 offset;
3180 // u1 type_argument_index;
3181 // }
3182 //
3183 if ((byte_i_ref + 3) > type_annotations_typeArray->length()) {
3184 log_debug(redefine, class, annotation)("length() is too small for a type_argument_target");
3185 return false;
3186 }
3187
3188 u2 offset = Bytes::get_Java_u2((address)
3189 type_annotations_typeArray->adr_at(byte_i_ref));
3190 byte_i_ref += 2;
3191 u1 type_argument_index = type_annotations_typeArray->at(byte_i_ref);
3192 byte_i_ref += 1;
3193
3194 log_debug(redefine, class, annotation)
3195 ("type_argument_target: offset=%d, type_argument_index=%d", offset, type_argument_index);
3196 } break;
3197
3198 default:
3199 log_debug(redefine, class, annotation)("unknown target_type");
3200 #ifdef ASSERT
3201 ShouldNotReachHere();
3202 #endif
3203 return false;
3204 }
3205
3206 return true;
3207 } // end skip_type_annotation_target()
3208
3209
3210 // Read, verify and skip over the type_path part so that rewriting
3211 // can continue in the later parts of the struct.
3212 //
3213 // type_path {
3214 // u1 path_length;
3215 // {
3216 // u1 type_path_kind;
3217 // u1 type_argument_index;
3218 // } path[path_length];
3219 // }
3220 //
3221 bool VM_RedefineClasses::skip_type_annotation_type_path(
3222 AnnotationArray* type_annotations_typeArray, int &byte_i_ref) {
3223
3224 if ((byte_i_ref + 1) > type_annotations_typeArray->length()) {
3225 // not enough room for a path_length let alone the rest of the type_path
3226 log_debug(redefine, class, annotation)("length() is too small for a type_path");
3227 return false;
3228 }
3229
3230 u1 path_length = type_annotations_typeArray->at(byte_i_ref);
3231 byte_i_ref += 1;
3232
3233 log_debug(redefine, class, annotation)("type_path: path_length=%d", path_length);
3234
3235 int calc_path_length = 0;
3236 for (; calc_path_length < path_length; calc_path_length++) {
3237 if ((byte_i_ref + 1 + 1) > type_annotations_typeArray->length()) {
3238 // not enough room for a path
3239 log_debug(redefine, class, annotation)
3240 ("length() is too small for path entry %d of %d", calc_path_length, path_length);
3241 return false;
3242 }
3243
3244 u1 type_path_kind = type_annotations_typeArray->at(byte_i_ref);
3245 byte_i_ref += 1;
3246 u1 type_argument_index = type_annotations_typeArray->at(byte_i_ref);
3247 byte_i_ref += 1;
3248
3249 log_debug(redefine, class, annotation)
3250 ("type_path: path[%d]: type_path_kind=%d, type_argument_index=%d",
3251 calc_path_length, type_path_kind, type_argument_index);
3252
3253 if (type_path_kind > 3 || (type_path_kind != 3 && type_argument_index != 0)) {
3254 // not enough room for a path
3255 log_debug(redefine, class, annotation)("inconsistent type_path values");
3256 return false;
3257 }
3258 }
3259 assert(path_length == calc_path_length, "sanity check");
3260
3261 return true;
3262 } // end skip_type_annotation_type_path()
3263
3264
3265 // Rewrite constant pool references in the method's stackmap table.
3266 // These "structures" are adapted from the StackMapTable_attribute that
3267 // is described in section 4.8.4 of the 6.0 version of the VM spec
3268 // (dated 2005.10.26):
3269 // file:///net/quincunx.sfbay/export/gbracha/ClassFile-Java6.pdf
3270 //
3271 // stack_map {
3272 // u2 number_of_entries;
3273 // stack_map_frame entries[number_of_entries];
3274 // }
3275 //
3276 void VM_RedefineClasses::rewrite_cp_refs_in_stack_map_table(
3277 const methodHandle& method) {
3278
3279 if (!method->has_stackmap_table()) {
3280 return;
3281 }
3282
3283 AnnotationArray* stackmap_data = method->stackmap_data();
3284 address stackmap_p = (address)stackmap_data->adr_at(0);
3285 address stackmap_end = stackmap_p + stackmap_data->length();
3286
3287 assert(stackmap_p + 2 <= stackmap_end, "no room for number_of_entries");
3288 u2 number_of_entries = Bytes::get_Java_u2(stackmap_p);
3289 stackmap_p += 2;
3290
3291 log_debug(redefine, class, stackmap)("number_of_entries=%u", number_of_entries);
3292
3293 // walk through each stack_map_frame
3294 u2 calc_number_of_entries = 0;
3295 for (; calc_number_of_entries < number_of_entries; calc_number_of_entries++) {
3296 // The stack_map_frame structure is a u1 frame_type followed by
3297 // 0 or more bytes of data:
3298 //
3299 // union stack_map_frame {
3300 // same_frame;
3301 // same_locals_1_stack_item_frame;
3302 // same_locals_1_stack_item_frame_extended;
3303 // chop_frame;
3304 // same_frame_extended;
3305 // append_frame;
3306 // full_frame;
3307 // }
3308
3309 assert(stackmap_p + 1 <= stackmap_end, "no room for frame_type");
3310 u1 frame_type = *stackmap_p;
3311 stackmap_p++;
3312
3313 // same_frame {
3314 // u1 frame_type = SAME; /* 0-63 */
3315 // }
3316 if (frame_type <= 63) {
3317 // nothing more to do for same_frame
3318 }
3319
3320 // same_locals_1_stack_item_frame {
3321 // u1 frame_type = SAME_LOCALS_1_STACK_ITEM; /* 64-127 */
3322 // verification_type_info stack[1];
3323 // }
3324 else if (frame_type >= 64 && frame_type <= 127) {
3325 rewrite_cp_refs_in_verification_type_info(stackmap_p, stackmap_end,
3326 calc_number_of_entries, frame_type);
3327 }
3328
3329 // reserved for future use
3330 else if (frame_type >= 128 && frame_type <= 246) {
3331 // nothing more to do for reserved frame_types
3332 }
3333
3334 // same_locals_1_stack_item_frame_extended {
3335 // u1 frame_type = SAME_LOCALS_1_STACK_ITEM_EXTENDED; /* 247 */
3336 // u2 offset_delta;
3337 // verification_type_info stack[1];
3338 // }
3339 else if (frame_type == 247) {
3340 stackmap_p += 2;
3341 rewrite_cp_refs_in_verification_type_info(stackmap_p, stackmap_end,
3342 calc_number_of_entries, frame_type);
3343 }
3344
3345 // chop_frame {
3346 // u1 frame_type = CHOP; /* 248-250 */
3347 // u2 offset_delta;
3348 // }
3349 else if (frame_type >= 248 && frame_type <= 250) {
3350 stackmap_p += 2;
3351 }
3352
3353 // same_frame_extended {
3354 // u1 frame_type = SAME_FRAME_EXTENDED; /* 251*/
3355 // u2 offset_delta;
3356 // }
3357 else if (frame_type == 251) {
3358 stackmap_p += 2;
3359 }
3360
3361 // append_frame {
3362 // u1 frame_type = APPEND; /* 252-254 */
3363 // u2 offset_delta;
3364 // verification_type_info locals[frame_type - 251];
3365 // }
3366 else if (frame_type >= 252 && frame_type <= 254) {
3367 assert(stackmap_p + 2 <= stackmap_end,
3368 "no room for offset_delta");
3369 stackmap_p += 2;
3370 u1 len = frame_type - 251;
3371 for (u1 i = 0; i < len; i++) {
3372 rewrite_cp_refs_in_verification_type_info(stackmap_p, stackmap_end,
3373 calc_number_of_entries, frame_type);
3374 }
3375 }
3376
3377 // full_frame {
3378 // u1 frame_type = FULL_FRAME; /* 255 */
3379 // u2 offset_delta;
3380 // u2 number_of_locals;
3381 // verification_type_info locals[number_of_locals];
3382 // u2 number_of_stack_items;
3383 // verification_type_info stack[number_of_stack_items];
3384 // }
3385 else if (frame_type == 255) {
3386 assert(stackmap_p + 2 + 2 <= stackmap_end,
3387 "no room for smallest full_frame");
3388 stackmap_p += 2;
3389
3390 u2 number_of_locals = Bytes::get_Java_u2(stackmap_p);
3391 stackmap_p += 2;
3392
3393 for (u2 locals_i = 0; locals_i < number_of_locals; locals_i++) {
3394 rewrite_cp_refs_in_verification_type_info(stackmap_p, stackmap_end,
3395 calc_number_of_entries, frame_type);
3396 }
3397
3398 // Use the largest size for the number_of_stack_items, but only get
3399 // the right number of bytes.
3400 u2 number_of_stack_items = Bytes::get_Java_u2(stackmap_p);
3401 stackmap_p += 2;
3402
3403 for (u2 stack_i = 0; stack_i < number_of_stack_items; stack_i++) {
3404 rewrite_cp_refs_in_verification_type_info(stackmap_p, stackmap_end,
3405 calc_number_of_entries, frame_type);
3406 }
3407 }
3408 } // end while there is a stack_map_frame
3409 assert(number_of_entries == calc_number_of_entries, "sanity check");
3410 } // end rewrite_cp_refs_in_stack_map_table()
3411
3412
3413 // Rewrite constant pool references in the verification type info
3414 // portion of the method's stackmap table. These "structures" are
3415 // adapted from the StackMapTable_attribute that is described in
3416 // section 4.8.4 of the 6.0 version of the VM spec (dated 2005.10.26):
3417 // file:///net/quincunx.sfbay/export/gbracha/ClassFile-Java6.pdf
3418 //
3419 // The verification_type_info structure is a u1 tag followed by 0 or
3420 // more bytes of data:
3421 //
3422 // union verification_type_info {
3423 // Top_variable_info;
3424 // Integer_variable_info;
3425 // Float_variable_info;
3426 // Long_variable_info;
3427 // Double_variable_info;
3428 // Null_variable_info;
3429 // UninitializedThis_variable_info;
3430 // Object_variable_info;
3431 // Uninitialized_variable_info;
3432 // }
3433 //
3434 void VM_RedefineClasses::rewrite_cp_refs_in_verification_type_info(
3435 address& stackmap_p_ref, address stackmap_end, u2 frame_i,
3436 u1 frame_type) {
3437
3438 assert(stackmap_p_ref + 1 <= stackmap_end, "no room for tag");
3439 u1 tag = *stackmap_p_ref;
3440 stackmap_p_ref++;
3441
3442 switch (tag) {
3443 // Top_variable_info {
3444 // u1 tag = ITEM_Top; /* 0 */
3445 // }
3446 // verificationType.hpp has zero as ITEM_Bogus instead of ITEM_Top
3447 case 0: // fall through
3448
3449 // Integer_variable_info {
3450 // u1 tag = ITEM_Integer; /* 1 */
3451 // }
3452 case ITEM_Integer: // fall through
3453
3454 // Float_variable_info {
3455 // u1 tag = ITEM_Float; /* 2 */
3456 // }
3457 case ITEM_Float: // fall through
3458
3459 // Double_variable_info {
3460 // u1 tag = ITEM_Double; /* 3 */
3461 // }
3462 case ITEM_Double: // fall through
3463
3464 // Long_variable_info {
3465 // u1 tag = ITEM_Long; /* 4 */
3466 // }
3467 case ITEM_Long: // fall through
3468
3469 // Null_variable_info {
3470 // u1 tag = ITEM_Null; /* 5 */
3471 // }
3472 case ITEM_Null: // fall through
3473
3474 // UninitializedThis_variable_info {
3475 // u1 tag = ITEM_UninitializedThis; /* 6 */
3476 // }
3477 case ITEM_UninitializedThis:
3478 // nothing more to do for the above tag types
3479 break;
3480
3481 // Object_variable_info {
3482 // u1 tag = ITEM_Object; /* 7 */
3483 // u2 cpool_index;
3484 // }
3485 case ITEM_Object:
3486 {
3487 assert(stackmap_p_ref + 2 <= stackmap_end, "no room for cpool_index");
3488 u2 cpool_index = Bytes::get_Java_u2(stackmap_p_ref);
3489 u2 new_cp_index = find_new_index(cpool_index);
3490 if (new_cp_index != 0) {
3491 log_debug(redefine, class, stackmap)("mapped old cpool_index=%d", cpool_index);
3492 Bytes::put_Java_u2(stackmap_p_ref, new_cp_index);
3493 cpool_index = new_cp_index;
3494 }
3495 stackmap_p_ref += 2;
3496
3497 log_debug(redefine, class, stackmap)
3498 ("frame_i=%u, frame_type=%u, cpool_index=%d", frame_i, frame_type, cpool_index);
3499 } break;
3500
3501 // Uninitialized_variable_info {
3502 // u1 tag = ITEM_Uninitialized; /* 8 */
3503 // u2 offset;
3504 // }
3505 case ITEM_Uninitialized:
3506 assert(stackmap_p_ref + 2 <= stackmap_end, "no room for offset");
3507 stackmap_p_ref += 2;
3508 break;
3509
3510 default:
3511 log_debug(redefine, class, stackmap)("frame_i=%u, frame_type=%u, bad tag=0x%x", frame_i, frame_type, tag);
3512 ShouldNotReachHere();
3513 break;
3514 } // end switch (tag)
3515 } // end rewrite_cp_refs_in_verification_type_info()
3516
3517
3518 // Change the constant pool associated with klass scratch_class to
3519 // scratch_cp. If shrink is true, then scratch_cp_length elements
3520 // are copied from scratch_cp to a smaller constant pool and the
3521 // smaller constant pool is associated with scratch_class.
3522 void VM_RedefineClasses::set_new_constant_pool(
3523 ClassLoaderData* loader_data,
3524 InstanceKlass* scratch_class, constantPoolHandle scratch_cp,
3525 int scratch_cp_length, TRAPS) {
3526 assert(scratch_cp->length() >= scratch_cp_length, "sanity check");
3527
3528 // scratch_cp is a merged constant pool and has enough space for a
3529 // worst case merge situation. We want to associate the minimum
3530 // sized constant pool with the klass to save space.
3531 ConstantPool* cp = ConstantPool::allocate(loader_data, scratch_cp_length, CHECK);
3532 constantPoolHandle smaller_cp(THREAD, cp);
3533
3534 // preserve version() value in the smaller copy
3535 int version = scratch_cp->version();
3536 assert(version != 0, "sanity check");
3537 smaller_cp->set_version(version);
3538
3539 // attach klass to new constant pool
3540 // reference to the cp holder is needed for copy_operands()
3541 smaller_cp->set_pool_holder(scratch_class);
3542
3543 smaller_cp->copy_fields(scratch_cp());
3544
3545 scratch_cp->copy_cp_to(1, scratch_cp_length - 1, smaller_cp, 1, THREAD);
3546 if (HAS_PENDING_EXCEPTION) {
3547 // Exception is handled in the caller
3548 loader_data->add_to_deallocate_list(smaller_cp());
3549 return;
3550 }
3551 scratch_cp = smaller_cp;
3552
3553 // attach new constant pool to klass
3554 scratch_class->set_constants(scratch_cp());
3555 scratch_cp->initialize_unresolved_klasses(loader_data, CHECK);
3556
3557 int i; // for portability
3558
3559 // update each field in klass to use new constant pool indices as needed
3560 for (JavaFieldStream fs(scratch_class); !fs.done(); fs.next()) {
3561 jshort cur_index = fs.name_index();
3562 jshort new_index = find_new_index(cur_index);
3563 if (new_index != 0) {
3564 log_trace(redefine, class, constantpool)("field-name_index change: %d to %d", cur_index, new_index);
3565 fs.set_name_index(new_index);
3566 }
3567 cur_index = fs.signature_index();
3568 new_index = find_new_index(cur_index);
3569 if (new_index != 0) {
3570 log_trace(redefine, class, constantpool)("field-signature_index change: %d to %d", cur_index, new_index);
3571 fs.set_signature_index(new_index);
3572 }
3573 cur_index = fs.initval_index();
3574 new_index = find_new_index(cur_index);
3575 if (new_index != 0) {
3576 log_trace(redefine, class, constantpool)("field-initval_index change: %d to %d", cur_index, new_index);
3577 fs.set_initval_index(new_index);
3578 }
3579 cur_index = fs.generic_signature_index();
3580 new_index = find_new_index(cur_index);
3581 if (new_index != 0) {
3582 log_trace(redefine, class, constantpool)("field-generic_signature change: %d to %d", cur_index, new_index);
3583 fs.set_generic_signature_index(new_index);
3584 }
3585 } // end for each field
3586
3587 // Update constant pool indices in the inner classes info to use
3588 // new constant indices as needed. The inner classes info is a
3589 // quadruple:
3590 // (inner_class_info, outer_class_info, inner_name, inner_access_flags)
3591 InnerClassesIterator iter(scratch_class);
3592 for (; !iter.done(); iter.next()) {
3593 int cur_index = iter.inner_class_info_index();
3594 if (cur_index == 0) {
3595 continue; // JVM spec. allows null inner class refs so skip it
3596 }
3597 int new_index = find_new_index(cur_index);
3598 if (new_index != 0) {
3599 log_trace(redefine, class, constantpool)("inner_class_info change: %d to %d", cur_index, new_index);
3600 iter.set_inner_class_info_index(new_index);
3601 }
3602 cur_index = iter.outer_class_info_index();
3603 new_index = find_new_index(cur_index);
3604 if (new_index != 0) {
3605 log_trace(redefine, class, constantpool)("outer_class_info change: %d to %d", cur_index, new_index);
3606 iter.set_outer_class_info_index(new_index);
3607 }
3608 cur_index = iter.inner_name_index();
3609 new_index = find_new_index(cur_index);
3610 if (new_index != 0) {
3611 log_trace(redefine, class, constantpool)("inner_name change: %d to %d", cur_index, new_index);
3612 iter.set_inner_name_index(new_index);
3613 }
3614 } // end for each inner class
3615
3616 // Attach each method in klass to the new constant pool and update
3617 // to use new constant pool indices as needed:
3618 Array<Method*>* methods = scratch_class->methods();
3619 for (i = methods->length() - 1; i >= 0; i--) {
3620 methodHandle method(THREAD, methods->at(i));
3621 method->set_constants(scratch_cp());
3622
3623 int new_index = find_new_index(method->name_index());
3624 if (new_index != 0) {
3625 log_trace(redefine, class, constantpool)
3626 ("method-name_index change: %d to %d", method->name_index(), new_index);
3627 method->set_name_index(new_index);
3628 }
3629 new_index = find_new_index(method->signature_index());
3630 if (new_index != 0) {
3631 log_trace(redefine, class, constantpool)
3632 ("method-signature_index change: %d to %d", method->signature_index(), new_index);
3633 method->set_signature_index(new_index);
3634 }
3635 new_index = find_new_index(method->generic_signature_index());
3636 if (new_index != 0) {
3637 log_trace(redefine, class, constantpool)
3638 ("method-generic_signature_index change: %d to %d", method->generic_signature_index(), new_index);
3639 method->set_generic_signature_index(new_index);
3640 }
3641
3642 // Update constant pool indices in the method's checked exception
3643 // table to use new constant indices as needed.
3644 int cext_length = method->checked_exceptions_length();
3645 if (cext_length > 0) {
3646 CheckedExceptionElement * cext_table =
3647 method->checked_exceptions_start();
3648 for (int j = 0; j < cext_length; j++) {
3649 int cur_index = cext_table[j].class_cp_index;
3650 int new_index = find_new_index(cur_index);
3651 if (new_index != 0) {
3652 log_trace(redefine, class, constantpool)("cext-class_cp_index change: %d to %d", cur_index, new_index);
3653 cext_table[j].class_cp_index = (u2)new_index;
3654 }
3655 } // end for each checked exception table entry
3656 } // end if there are checked exception table entries
3657
3658 // Update each catch type index in the method's exception table
3659 // to use new constant pool indices as needed. The exception table
3660 // holds quadruple entries of the form:
3661 // (beg_bci, end_bci, handler_bci, klass_index)
3662
3663 ExceptionTable ex_table(method());
3664 int ext_length = ex_table.length();
3665
3666 for (int j = 0; j < ext_length; j ++) {
3667 int cur_index = ex_table.catch_type_index(j);
3668 int new_index = find_new_index(cur_index);
3669 if (new_index != 0) {
3670 log_trace(redefine, class, constantpool)("ext-klass_index change: %d to %d", cur_index, new_index);
3671 ex_table.set_catch_type_index(j, new_index);
3672 }
3673 } // end for each exception table entry
3674
3675 // Update constant pool indices in the method's local variable
3676 // table to use new constant indices as needed. The local variable
3677 // table hold sextuple entries of the form:
3678 // (start_pc, length, name_index, descriptor_index, signature_index, slot)
3679 int lvt_length = method->localvariable_table_length();
3680 if (lvt_length > 0) {
3681 LocalVariableTableElement * lv_table =
3682 method->localvariable_table_start();
3683 for (int j = 0; j < lvt_length; j++) {
3684 int cur_index = lv_table[j].name_cp_index;
3685 int new_index = find_new_index(cur_index);
3686 if (new_index != 0) {
3687 log_trace(redefine, class, constantpool)("lvt-name_cp_index change: %d to %d", cur_index, new_index);
3688 lv_table[j].name_cp_index = (u2)new_index;
3689 }
3690 cur_index = lv_table[j].descriptor_cp_index;
3691 new_index = find_new_index(cur_index);
3692 if (new_index != 0) {
3693 log_trace(redefine, class, constantpool)("lvt-descriptor_cp_index change: %d to %d", cur_index, new_index);
3694 lv_table[j].descriptor_cp_index = (u2)new_index;
3695 }
3696 cur_index = lv_table[j].signature_cp_index;
3697 new_index = find_new_index(cur_index);
3698 if (new_index != 0) {
3699 log_trace(redefine, class, constantpool)("lvt-signature_cp_index change: %d to %d", cur_index, new_index);
3700 lv_table[j].signature_cp_index = (u2)new_index;
3701 }
3702 } // end for each local variable table entry
3703 } // end if there are local variable table entries
3704
3705 rewrite_cp_refs_in_stack_map_table(method);
3706 } // end for each method
3707 } // end set_new_constant_pool()
3708
3709
3710 // Unevolving classes may point to methods of the_class directly
3711 // from their constant pool caches, itables, and/or vtables. We
3712 // use the ClassLoaderDataGraph::classes_do() facility and this helper
3713 // to fix up these pointers. MethodData also points to old methods and
3714 // must be cleaned.
3715
3716 // Adjust cpools and vtables closure
3717 void VM_RedefineClasses::AdjustAndCleanMetadata::do_klass(Klass* k) {
3718
3719 // This is a very busy routine. We don't want too much tracing
3720 // printed out.
3721 bool trace_name_printed = false;
3722
3723 // If the class being redefined is java.lang.Object, we need to fix all
3724 // array class vtables also. The _has_redefined_Object flag is global.
3725 // Once the java.lang.Object has been redefined (by the current or one
3726 // of the previous VM_RedefineClasses operations) we have to always
3727 // adjust method entries for array classes.
3728 if (k->is_array_klass() && _has_redefined_Object) {
3729 k->vtable().adjust_method_entries(&trace_name_printed);
3730
3731 } else if (k->is_instance_klass()) {
3732 HandleMark hm(_thread);
3733 InstanceKlass *ik = InstanceKlass::cast(k);
3734
3735 // Clean MethodData of this class's methods so they don't refer to
3736 // old methods that are no longer running.
3737 Array<Method*>* methods = ik->methods();
3738 int num_methods = methods->length();
3739 for (int index = 0; index < num_methods; ++index) {
3740 if (methods->at(index)->method_data() != NULL) {
3741 methods->at(index)->method_data()->clean_weak_method_links();
3742 }
3743 }
3744
3745 // Adjust all vtables, default methods and itables, to clean out old methods.
3746 ResourceMark rm(_thread);
3747 if (ik->vtable_length() > 0) {
3748 ik->vtable().adjust_method_entries(&trace_name_printed);
3749 ik->adjust_default_methods(&trace_name_printed);
3750 }
3751
3752 if (ik->itable_length() > 0) {
3753 ik->itable().adjust_method_entries(&trace_name_printed);
3754 }
3755
3756 // The constant pools in other classes (other_cp) can refer to
3757 // old methods. We have to update method information in
3758 // other_cp's cache. If other_cp has a previous version, then we
3759 // have to repeat the process for each previous version. The
3760 // constant pool cache holds the Method*s for non-virtual
3761 // methods and for virtual, final methods.
3762 //
3763 // Special case: if the current class is being redefined by the current
3764 // VM_RedefineClasses operation, then new_cp has already been attached
3765 // to the_class and old_cp has already been added as a previous version.
3766 // The new_cp doesn't have any cached references to old methods so it
3767 // doesn't need to be updated and we could optimize by skipping it.
3768 // However, the current class can be marked as being redefined by another
3769 // VM_RedefineClasses operation which has already executed its doit_prologue
3770 // and needs cpcache method entries adjusted. For simplicity, the cpcache
3771 // update is done unconditionally. It should result in doing nothing for
3772 // classes being redefined by the current VM_RedefineClasses operation.
3773 // Method entries in the previous version(s) are adjusted as well.
3774 ConstantPoolCache* cp_cache;
3775
3776 // this klass' constant pool cache may need adjustment
3777 ConstantPool* other_cp = ik->constants();
3778 cp_cache = other_cp->cache();
3779 if (cp_cache != NULL) {
3780 cp_cache->adjust_method_entries(&trace_name_printed);
3781 }
3782
3783 // the previous versions' constant pool caches may need adjustment
3784 for (InstanceKlass* pv_node = ik->previous_versions();
3785 pv_node != NULL;
3786 pv_node = pv_node->previous_versions()) {
3787 cp_cache = pv_node->constants()->cache();
3788 if (cp_cache != NULL) {
3789 cp_cache->adjust_method_entries(&trace_name_printed);
3790 }
3791 }
3792 }
3793 }
3794
3795 void VM_RedefineClasses::update_jmethod_ids() {
3796 for (int j = 0; j < _matching_methods_length; ++j) {
3797 Method* old_method = _matching_old_methods[j];
3798 jmethodID jmid = old_method->find_jmethod_id_or_null();
3799 if (jmid != NULL) {
3800 // There is a jmethodID, change it to point to the new method
3801 Method* new_method = _matching_new_methods[j];
3802 Method::change_method_associated_with_jmethod_id(jmid, new_method);
3803 assert(Method::resolve_jmethod_id(jmid) == _matching_new_methods[j],
3804 "should be replaced");
3805 }
3806 }
3807 }
3808
3809 int VM_RedefineClasses::check_methods_and_mark_as_obsolete() {
3810 int emcp_method_count = 0;
3811 int obsolete_count = 0;
3812 int old_index = 0;
3813 for (int j = 0; j < _matching_methods_length; ++j, ++old_index) {
3814 Method* old_method = _matching_old_methods[j];
3815 Method* new_method = _matching_new_methods[j];
3816 Method* old_array_method;
3817
3818 // Maintain an old_index into the _old_methods array by skipping
3819 // deleted methods
3820 while ((old_array_method = _old_methods->at(old_index)) != old_method) {
3821 ++old_index;
3822 }
3823
3824 if (MethodComparator::methods_EMCP(old_method, new_method)) {
3825 // The EMCP definition from JSR-163 requires the bytecodes to be
3826 // the same with the exception of constant pool indices which may
3827 // differ. However, the constants referred to by those indices
3828 // must be the same.
3829 //
3830 // We use methods_EMCP() for comparison since constant pool
3831 // merging can remove duplicate constant pool entries that were
3832 // present in the old method and removed from the rewritten new
3833 // method. A faster binary comparison function would consider the
3834 // old and new methods to be different when they are actually
3835 // EMCP.
3836 //
3837 // The old and new methods are EMCP and you would think that we
3838 // could get rid of one of them here and now and save some space.
3839 // However, the concept of EMCP only considers the bytecodes and
3840 // the constant pool entries in the comparison. Other things,
3841 // e.g., the line number table (LNT) or the local variable table
3842 // (LVT) don't count in the comparison. So the new (and EMCP)
3843 // method can have a new LNT that we need so we can't just
3844 // overwrite the new method with the old method.
3845 //
3846 // When this routine is called, we have already attached the new
3847 // methods to the_class so the old methods are effectively
3848 // overwritten. However, if an old method is still executing,
3849 // then the old method cannot be collected until sometime after
3850 // the old method call has returned. So the overwriting of old
3851 // methods by new methods will save us space except for those
3852 // (hopefully few) old methods that are still executing.
3853 //
3854 // A method refers to a ConstMethod* and this presents another
3855 // possible avenue to space savings. The ConstMethod* in the
3856 // new method contains possibly new attributes (LNT, LVT, etc).
3857 // At first glance, it seems possible to save space by replacing
3858 // the ConstMethod* in the old method with the ConstMethod*
3859 // from the new method. The old and new methods would share the
3860 // same ConstMethod* and we would save the space occupied by
3861 // the old ConstMethod*. However, the ConstMethod* contains
3862 // a back reference to the containing method. Sharing the
3863 // ConstMethod* between two methods could lead to confusion in
3864 // the code that uses the back reference. This would lead to
3865 // brittle code that could be broken in non-obvious ways now or
3866 // in the future.
3867 //
3868 // Another possibility is to copy the ConstMethod* from the new
3869 // method to the old method and then overwrite the new method with
3870 // the old method. Since the ConstMethod* contains the bytecodes
3871 // for the method embedded in the oop, this option would change
3872 // the bytecodes out from under any threads executing the old
3873 // method and make the thread's bcp invalid. Since EMCP requires
3874 // that the bytecodes be the same modulo constant pool indices, it
3875 // is straight forward to compute the correct new bcp in the new
3876 // ConstMethod* from the old bcp in the old ConstMethod*. The
3877 // time consuming part would be searching all the frames in all
3878 // of the threads to find all of the calls to the old method.
3879 //
3880 // It looks like we will have to live with the limited savings
3881 // that we get from effectively overwriting the old methods
3882 // when the new methods are attached to the_class.
3883
3884 // Count number of methods that are EMCP. The method will be marked
3885 // old but not obsolete if it is EMCP.
3886 emcp_method_count++;
3887
3888 // An EMCP method is _not_ obsolete. An obsolete method has a
3889 // different jmethodID than the current method. An EMCP method
3890 // has the same jmethodID as the current method. Having the
3891 // same jmethodID for all EMCP versions of a method allows for
3892 // a consistent view of the EMCP methods regardless of which
3893 // EMCP method you happen to have in hand. For example, a
3894 // breakpoint set in one EMCP method will work for all EMCP
3895 // versions of the method including the current one.
3896 } else {
3897 // mark obsolete methods as such
3898 old_method->set_is_obsolete();
3899 obsolete_count++;
3900
3901 // obsolete methods need a unique idnum so they become new entries in
3902 // the jmethodID cache in InstanceKlass
3903 assert(old_method->method_idnum() == new_method->method_idnum(), "must match");
3904 u2 num = InstanceKlass::cast(_the_class)->next_method_idnum();
3905 if (num != ConstMethod::UNSET_IDNUM) {
3906 old_method->set_method_idnum(num);
3907 }
3908
3909 // With tracing we try not to "yack" too much. The position of
3910 // this trace assumes there are fewer obsolete methods than
3911 // EMCP methods.
3912 if (log_is_enabled(Trace, redefine, class, obsolete, mark)) {
3913 ResourceMark rm;
3914 log_trace(redefine, class, obsolete, mark)
3915 ("mark %s(%s) as obsolete", old_method->name()->as_C_string(), old_method->signature()->as_C_string());
3916 }
3917 }
3918 old_method->set_is_old();
3919 }
3920 for (int i = 0; i < _deleted_methods_length; ++i) {
3921 Method* old_method = _deleted_methods[i];
3922
3923 assert(!old_method->has_vtable_index(),
3924 "cannot delete methods with vtable entries");;
3925
3926 // Mark all deleted methods as old, obsolete and deleted
3927 old_method->set_is_deleted();
3928 old_method->set_is_old();
3929 old_method->set_is_obsolete();
3930 ++obsolete_count;
3931 // With tracing we try not to "yack" too much. The position of
3932 // this trace assumes there are fewer obsolete methods than
3933 // EMCP methods.
3934 if (log_is_enabled(Trace, redefine, class, obsolete, mark)) {
3935 ResourceMark rm;
3936 log_trace(redefine, class, obsolete, mark)
3937 ("mark deleted %s(%s) as obsolete", old_method->name()->as_C_string(), old_method->signature()->as_C_string());
3938 }
3939 }
3940 assert((emcp_method_count + obsolete_count) == _old_methods->length(),
3941 "sanity check");
3942 log_trace(redefine, class, obsolete, mark)("EMCP_cnt=%d, obsolete_cnt=%d", emcp_method_count, obsolete_count);
3943 return emcp_method_count;
3944 }
3945
3946 // This internal class transfers the native function registration from old methods
3947 // to new methods. It is designed to handle both the simple case of unchanged
3948 // native methods and the complex cases of native method prefixes being added and/or
3949 // removed.
3950 // It expects only to be used during the VM_RedefineClasses op (a safepoint).
3951 //
3952 // This class is used after the new methods have been installed in "the_class".
3953 //
3954 // So, for example, the following must be handled. Where 'm' is a method and
3955 // a number followed by an underscore is a prefix.
3956 //
3957 // Old Name New Name
3958 // Simple transfer to new method m -> m
3959 // Add prefix m -> 1_m
3960 // Remove prefix 1_m -> m
3961 // Simultaneous add of prefixes m -> 3_2_1_m
3962 // Simultaneous removal of prefixes 3_2_1_m -> m
3963 // Simultaneous add and remove 1_m -> 2_m
3964 // Same, caused by prefix removal only 3_2_1_m -> 3_2_m
3965 //
3966 class TransferNativeFunctionRegistration {
3967 private:
3968 InstanceKlass* the_class;
3969 int prefix_count;
3970 char** prefixes;
3971
3972 // Recursively search the binary tree of possibly prefixed method names.
3973 // Iteration could be used if all agents were well behaved. Full tree walk is
3974 // more resilent to agents not cleaning up intermediate methods.
3975 // Branch at each depth in the binary tree is:
3976 // (1) without the prefix.
3977 // (2) with the prefix.
3978 // where 'prefix' is the prefix at that 'depth' (first prefix, second prefix,...)
3979 Method* search_prefix_name_space(int depth, char* name_str, size_t name_len,
3980 Symbol* signature) {
3981 TempNewSymbol name_symbol = SymbolTable::probe(name_str, (int)name_len);
3982 if (name_symbol != NULL) {
3983 Method* method = the_class->lookup_method(name_symbol, signature);
3984 if (method != NULL) {
3985 // Even if prefixed, intermediate methods must exist.
3986 if (method->is_native()) {
3987 // Wahoo, we found a (possibly prefixed) version of the method, return it.
3988 return method;
3989 }
3990 if (depth < prefix_count) {
3991 // Try applying further prefixes (other than this one).
3992 method = search_prefix_name_space(depth+1, name_str, name_len, signature);
3993 if (method != NULL) {
3994 return method; // found
3995 }
3996
3997 // Try adding this prefix to the method name and see if it matches
3998 // another method name.
3999 char* prefix = prefixes[depth];
4000 size_t prefix_len = strlen(prefix);
4001 size_t trial_len = name_len + prefix_len;
4002 char* trial_name_str = NEW_RESOURCE_ARRAY(char, trial_len + 1);
4003 strcpy(trial_name_str, prefix);
4004 strcat(trial_name_str, name_str);
4005 method = search_prefix_name_space(depth+1, trial_name_str, trial_len,
4006 signature);
4007 if (method != NULL) {
4008 // If found along this branch, it was prefixed, mark as such
4009 method->set_is_prefixed_native();
4010 return method; // found
4011 }
4012 }
4013 }
4014 }
4015 return NULL; // This whole branch bore nothing
4016 }
4017
4018 // Return the method name with old prefixes stripped away.
4019 char* method_name_without_prefixes(Method* method) {
4020 Symbol* name = method->name();
4021 char* name_str = name->as_utf8();
4022
4023 // Old prefixing may be defunct, strip prefixes, if any.
4024 for (int i = prefix_count-1; i >= 0; i--) {
4025 char* prefix = prefixes[i];
4026 size_t prefix_len = strlen(prefix);
4027 if (strncmp(prefix, name_str, prefix_len) == 0) {
4028 name_str += prefix_len;
4029 }
4030 }
4031 return name_str;
4032 }
4033
4034 // Strip any prefixes off the old native method, then try to find a
4035 // (possibly prefixed) new native that matches it.
4036 Method* strip_and_search_for_new_native(Method* method) {
4037 ResourceMark rm;
4038 char* name_str = method_name_without_prefixes(method);
4039 return search_prefix_name_space(0, name_str, strlen(name_str),
4040 method->signature());
4041 }
4042
4043 public:
4044
4045 // Construct a native method transfer processor for this class.
4046 TransferNativeFunctionRegistration(InstanceKlass* _the_class) {
4047 assert(SafepointSynchronize::is_at_safepoint(), "sanity check");
4048
4049 the_class = _the_class;
4050 prefixes = JvmtiExport::get_all_native_method_prefixes(&prefix_count);
4051 }
4052
4053 // Attempt to transfer any of the old or deleted methods that are native
4054 void transfer_registrations(Method** old_methods, int methods_length) {
4055 for (int j = 0; j < methods_length; j++) {
4056 Method* old_method = old_methods[j];
4057
4058 if (old_method->is_native() && old_method->has_native_function()) {
4059 Method* new_method = strip_and_search_for_new_native(old_method);
4060 if (new_method != NULL) {
4061 // Actually set the native function in the new method.
4062 // Redefine does not send events (except CFLH), certainly not this
4063 // behind the scenes re-registration.
4064 new_method->set_native_function(old_method->native_function(),
4065 !Method::native_bind_event_is_interesting);
4066 }
4067 }
4068 }
4069 }
4070 };
4071
4072 // Don't lose the association between a native method and its JNI function.
4073 void VM_RedefineClasses::transfer_old_native_function_registrations(InstanceKlass* the_class) {
4074 TransferNativeFunctionRegistration transfer(the_class);
4075 transfer.transfer_registrations(_deleted_methods, _deleted_methods_length);
4076 transfer.transfer_registrations(_matching_old_methods, _matching_methods_length);
4077 }
4078
4079 // Deoptimize all compiled code that depends on the classes redefined.
4080 //
4081 // If the can_redefine_classes capability is obtained in the onload
4082 // phase then the compiler has recorded all dependencies from startup.
4083 // In that case we need only deoptimize and throw away all compiled code
4084 // that depends on the class.
4085 //
4086 // If can_redefine_classes is obtained sometime after the onload
4087 // phase then the dependency information may be incomplete. In that case
4088 // the first call to RedefineClasses causes all compiled code to be
4089 // thrown away. As can_redefine_classes has been obtained then
4090 // all future compilations will record dependencies so second and
4091 // subsequent calls to RedefineClasses need only throw away code
4092 // that depends on the class.
4093 //
4094
4095 void VM_RedefineClasses::flush_dependent_code() {
4096 assert(SafepointSynchronize::is_at_safepoint(), "sanity check");
4097
4098 bool deopt_needed;
4099
4100 // This is the first redefinition, mark all the nmethods for deoptimization
4101 if (!JvmtiExport::all_dependencies_are_recorded()) {
4102 log_debug(redefine, class, nmethod)("Marked all nmethods for deopt");
4103 CodeCache::mark_all_nmethods_for_evol_deoptimization();
4104 deopt_needed = true;
4105 } else {
4106 int deopt = CodeCache::mark_dependents_for_evol_deoptimization();
4107 log_debug(redefine, class, nmethod)("Marked %d dependent nmethods for deopt", deopt);
4108 deopt_needed = (deopt != 0);
4109 }
4110
4111 if (deopt_needed) {
4112 CodeCache::flush_evol_dependents();
4113 }
4114
4115 // From now on we know that the dependency information is complete
4116 JvmtiExport::set_all_dependencies_are_recorded(true);
4117 }
4118
4119 void VM_RedefineClasses::compute_added_deleted_matching_methods() {
4120 Method* old_method;
4121 Method* new_method;
4122
4123 _matching_old_methods = NEW_RESOURCE_ARRAY(Method*, _old_methods->length());
4124 _matching_new_methods = NEW_RESOURCE_ARRAY(Method*, _old_methods->length());
4125 _added_methods = NEW_RESOURCE_ARRAY(Method*, _new_methods->length());
4126 _deleted_methods = NEW_RESOURCE_ARRAY(Method*, _old_methods->length());
4127
4128 _matching_methods_length = 0;
4129 _deleted_methods_length = 0;
4130 _added_methods_length = 0;
4131
4132 int nj = 0;
4133 int oj = 0;
4134 while (true) {
4135 if (oj >= _old_methods->length()) {
4136 if (nj >= _new_methods->length()) {
4137 break; // we've looked at everything, done
4138 }
4139 // New method at the end
4140 new_method = _new_methods->at(nj);
4141 _added_methods[_added_methods_length++] = new_method;
4142 ++nj;
4143 } else if (nj >= _new_methods->length()) {
4144 // Old method, at the end, is deleted
4145 old_method = _old_methods->at(oj);
4146 _deleted_methods[_deleted_methods_length++] = old_method;
4147 ++oj;
4148 } else {
4149 old_method = _old_methods->at(oj);
4150 new_method = _new_methods->at(nj);
4151 if (old_method->name() == new_method->name()) {
4152 if (old_method->signature() == new_method->signature()) {
4153 _matching_old_methods[_matching_methods_length ] = old_method;
4154 _matching_new_methods[_matching_methods_length++] = new_method;
4155 ++nj;
4156 ++oj;
4157 } else {
4158 // added overloaded have already been moved to the end,
4159 // so this is a deleted overloaded method
4160 _deleted_methods[_deleted_methods_length++] = old_method;
4161 ++oj;
4162 }
4163 } else { // names don't match
4164 if (old_method->name()->fast_compare(new_method->name()) > 0) {
4165 // new method
4166 _added_methods[_added_methods_length++] = new_method;
4167 ++nj;
4168 } else {
4169 // deleted method
4170 _deleted_methods[_deleted_methods_length++] = old_method;
4171 ++oj;
4172 }
4173 }
4174 }
4175 }
4176 assert(_matching_methods_length + _deleted_methods_length == _old_methods->length(), "sanity");
4177 assert(_matching_methods_length + _added_methods_length == _new_methods->length(), "sanity");
4178 }
4179
4180
4181 void VM_RedefineClasses::swap_annotations(InstanceKlass* the_class,
4182 InstanceKlass* scratch_class) {
4183 // Swap annotation fields values
4184 Annotations* old_annotations = the_class->annotations();
4185 the_class->set_annotations(scratch_class->annotations());
4186 scratch_class->set_annotations(old_annotations);
4187 }
4188
4189
4190 // Install the redefinition of a class:
4191 // - house keeping (flushing breakpoints and caches, deoptimizing
4192 // dependent compiled code)
4193 // - replacing parts in the_class with parts from scratch_class
4194 // - adding a weak reference to track the obsolete but interesting
4195 // parts of the_class
4196 // - adjusting constant pool caches and vtables in other classes
4197 // that refer to methods in the_class. These adjustments use the
4198 // ClassLoaderDataGraph::classes_do() facility which only allows
4199 // a helper method to be specified. The interesting parameters
4200 // that we would like to pass to the helper method are saved in
4201 // static global fields in the VM operation.
4202 void VM_RedefineClasses::redefine_single_class(Thread* current, jclass the_jclass,
4203 InstanceKlass* scratch_class) {
4204
4205 HandleMark hm(current); // make sure handles from this call are freed
4206
4207 if (log_is_enabled(Info, redefine, class, timer)) {
4208 _timer_rsc_phase1.start();
4209 }
4210
4211 InstanceKlass* the_class = get_ik(the_jclass);
4212
4213 // Set a flag to control and optimize adjusting method entries
4214 _has_redefined_Object |= the_class == vmClasses::Object_klass();
4215
4216 // Remove all breakpoints in methods of this class
4217 JvmtiBreakpoints& jvmti_breakpoints = JvmtiCurrentBreakpoints::get_jvmti_breakpoints();
4218 jvmti_breakpoints.clearall_in_class_at_safepoint(the_class);
4219
4220 _old_methods = the_class->methods();
4221 _new_methods = scratch_class->methods();
4222 _the_class = the_class;
4223 compute_added_deleted_matching_methods();
4224 update_jmethod_ids();
4225
4226 _any_class_has_resolved_methods = the_class->has_resolved_methods() || _any_class_has_resolved_methods;
4227
4228 // Attach new constant pool to the original klass. The original
4229 // klass still refers to the old constant pool (for now).
4230 scratch_class->constants()->set_pool_holder(the_class);
4231
4232 #if 0
4233 // In theory, with constant pool merging in place we should be able
4234 // to save space by using the new, merged constant pool in place of
4235 // the old constant pool(s). By "pool(s)" I mean the constant pool in
4236 // the klass version we are replacing now and any constant pool(s) in
4237 // previous versions of klass. Nice theory, doesn't work in practice.
4238 // When this code is enabled, even simple programs throw NullPointer
4239 // exceptions. I'm guessing that this is caused by some constant pool
4240 // cache difference between the new, merged constant pool and the
4241 // constant pool that was just being used by the klass. I'm keeping
4242 // this code around to archive the idea, but the code has to remain
4243 // disabled for now.
4244
4245 // Attach each old method to the new constant pool. This can be
4246 // done here since we are past the bytecode verification and
4247 // constant pool optimization phases.
4248 for (int i = _old_methods->length() - 1; i >= 0; i--) {
4249 Method* method = _old_methods->at(i);
4250 method->set_constants(scratch_class->constants());
4251 }
4252
4253 // NOTE: this doesn't work because you can redefine the same class in two
4254 // threads, each getting their own constant pool data appended to the
4255 // original constant pool. In order for the new methods to work when they
4256 // become old methods, they need to keep their updated copy of the constant pool.
4257
4258 {
4259 // walk all previous versions of the klass
4260 InstanceKlass *ik = the_class;
4261 PreviousVersionWalker pvw(ik);
4262 do {
4263 ik = pvw.next_previous_version();
4264 if (ik != NULL) {
4265
4266 // attach previous version of klass to the new constant pool
4267 ik->set_constants(scratch_class->constants());
4268
4269 // Attach each method in the previous version of klass to the
4270 // new constant pool
4271 Array<Method*>* prev_methods = ik->methods();
4272 for (int i = prev_methods->length() - 1; i >= 0; i--) {
4273 Method* method = prev_methods->at(i);
4274 method->set_constants(scratch_class->constants());
4275 }
4276 }
4277 } while (ik != NULL);
4278 }
4279 #endif
4280
4281 // Replace methods and constantpool
4282 the_class->set_methods(_new_methods);
4283 scratch_class->set_methods(_old_methods); // To prevent potential GCing of the old methods,
4284 // and to be able to undo operation easily.
4285
4286 Array<int>* old_ordering = the_class->method_ordering();
4287 the_class->set_method_ordering(scratch_class->method_ordering());
4288 scratch_class->set_method_ordering(old_ordering);
4289
4290 ConstantPool* old_constants = the_class->constants();
4291 the_class->set_constants(scratch_class->constants());
4292 scratch_class->set_constants(old_constants); // See the previous comment.
4293 #if 0
4294 // We are swapping the guts of "the new class" with the guts of "the
4295 // class". Since the old constant pool has just been attached to "the
4296 // new class", it seems logical to set the pool holder in the old
4297 // constant pool also. However, doing this will change the observable
4298 // class hierarchy for any old methods that are still executing. A
4299 // method can query the identity of its "holder" and this query uses
4300 // the method's constant pool link to find the holder. The change in
4301 // holding class from "the class" to "the new class" can confuse
4302 // things.
4303 //
4304 // Setting the old constant pool's holder will also cause
4305 // verification done during vtable initialization below to fail.
4306 // During vtable initialization, the vtable's class is verified to be
4307 // a subtype of the method's holder. The vtable's class is "the
4308 // class" and the method's holder is gotten from the constant pool
4309 // link in the method itself. For "the class"'s directly implemented
4310 // methods, the method holder is "the class" itself (as gotten from
4311 // the new constant pool). The check works fine in this case. The
4312 // check also works fine for methods inherited from super classes.
4313 //
4314 // Miranda methods are a little more complicated. A miranda method is
4315 // provided by an interface when the class implementing the interface
4316 // does not provide its own method. These interfaces are implemented
4317 // internally as an InstanceKlass. These special instanceKlasses
4318 // share the constant pool of the class that "implements" the
4319 // interface. By sharing the constant pool, the method holder of a
4320 // miranda method is the class that "implements" the interface. In a
4321 // non-redefine situation, the subtype check works fine. However, if
4322 // the old constant pool's pool holder is modified, then the check
4323 // fails because there is no class hierarchy relationship between the
4324 // vtable's class and "the new class".
4325
4326 old_constants->set_pool_holder(scratch_class());
4327 #endif
4328
4329 // track number of methods that are EMCP for add_previous_version() call below
4330 int emcp_method_count = check_methods_and_mark_as_obsolete();
4331 transfer_old_native_function_registrations(the_class);
4332
4333 // The class file bytes from before any retransformable agents mucked
4334 // with them was cached on the scratch class, move to the_class.
4335 // Note: we still want to do this if nothing needed caching since it
4336 // should get cleared in the_class too.
4337 if (the_class->get_cached_class_file() == 0) {
4338 // the_class doesn't have a cache yet so copy it
4339 the_class->set_cached_class_file(scratch_class->get_cached_class_file());
4340 }
4341 else if (scratch_class->get_cached_class_file() !=
4342 the_class->get_cached_class_file()) {
4343 // The same class can be present twice in the scratch classes list or there
4344 // are multiple concurrent RetransformClasses calls on different threads.
4345 // In such cases we have to deallocate scratch_class cached_class_file.
4346 os::free(scratch_class->get_cached_class_file());
4347 }
4348
4349 // NULL out in scratch class to not delete twice. The class to be redefined
4350 // always owns these bytes.
4351 scratch_class->set_cached_class_file(NULL);
4352
4353 // Replace inner_classes
4354 Array<u2>* old_inner_classes = the_class->inner_classes();
4355 the_class->set_inner_classes(scratch_class->inner_classes());
4356 scratch_class->set_inner_classes(old_inner_classes);
4357
4358 // Initialize the vtable and interface table after
4359 // methods have been rewritten
4360 // no exception should happen here since we explicitly
4361 // do not check loader constraints.
4362 // compare_and_normalize_class_versions has already checked:
4363 // - classloaders unchanged, signatures unchanged
4364 // - all instanceKlasses for redefined classes reused & contents updated
4365 the_class->vtable().initialize_vtable();
4366 the_class->itable().initialize_itable();
4367
4368 // Leave arrays of jmethodIDs and itable index cache unchanged
4369
4370 // Copy the "source file name" attribute from new class version
4371 the_class->set_source_file_name_index(
4372 scratch_class->source_file_name_index());
4373
4374 // Copy the "source debug extension" attribute from new class version
4375 the_class->set_source_debug_extension(
4376 scratch_class->source_debug_extension(),
4377 scratch_class->source_debug_extension() == NULL ? 0 :
4378 (int)strlen(scratch_class->source_debug_extension()));
4379
4380 // Use of javac -g could be different in the old and the new
4381 if (scratch_class->access_flags().has_localvariable_table() !=
4382 the_class->access_flags().has_localvariable_table()) {
4383
4384 AccessFlags flags = the_class->access_flags();
4385 if (scratch_class->access_flags().has_localvariable_table()) {
4386 flags.set_has_localvariable_table();
4387 } else {
4388 flags.clear_has_localvariable_table();
4389 }
4390 the_class->set_access_flags(flags);
4391 }
4392
4393 swap_annotations(the_class, scratch_class);
4394
4395 // Replace minor version number of class file
4396 u2 old_minor_version = the_class->constants()->minor_version();
4397 the_class->constants()->set_minor_version(scratch_class->constants()->minor_version());
4398 scratch_class->constants()->set_minor_version(old_minor_version);
4399
4400 // Replace major version number of class file
4401 u2 old_major_version = the_class->constants()->major_version();
4402 the_class->constants()->set_major_version(scratch_class->constants()->major_version());
4403 scratch_class->constants()->set_major_version(old_major_version);
4404
4405 // Replace CP indexes for class and name+type of enclosing method
4406 u2 old_class_idx = the_class->enclosing_method_class_index();
4407 u2 old_method_idx = the_class->enclosing_method_method_index();
4408 the_class->set_enclosing_method_indices(
4409 scratch_class->enclosing_method_class_index(),
4410 scratch_class->enclosing_method_method_index());
4411 scratch_class->set_enclosing_method_indices(old_class_idx, old_method_idx);
4412
4413 the_class->set_has_been_redefined();
4414
4415 // keep track of previous versions of this class
4416 the_class->add_previous_version(scratch_class, emcp_method_count);
4417
4418 _timer_rsc_phase1.stop();
4419 if (log_is_enabled(Info, redefine, class, timer)) {
4420 _timer_rsc_phase2.start();
4421 }
4422
4423 if (the_class->oop_map_cache() != NULL) {
4424 // Flush references to any obsolete methods from the oop map cache
4425 // so that obsolete methods are not pinned.
4426 the_class->oop_map_cache()->flush_obsolete_entries();
4427 }
4428
4429 increment_class_counter(the_class);
4430
4431 if (EventClassRedefinition::is_enabled()) {
4432 EventClassRedefinition event;
4433 event.set_classModificationCount(java_lang_Class::classRedefinedCount(the_class->java_mirror()));
4434 event.set_redefinedClass(the_class);
4435 event.set_redefinitionId(_id);
4436 event.commit();
4437 }
4438
4439 {
4440 ResourceMark rm(current);
4441 // increment the classRedefinedCount field in the_class and in any
4442 // direct and indirect subclasses of the_class
4443 log_info(redefine, class, load)
4444 ("redefined name=%s, count=%d (avail_mem=" UINT64_FORMAT "K)",
4445 the_class->external_name(), java_lang_Class::classRedefinedCount(the_class->java_mirror()), os::available_memory() >> 10);
4446 Events::log_redefinition(current, "redefined class name=%s, count=%d",
4447 the_class->external_name(),
4448 java_lang_Class::classRedefinedCount(the_class->java_mirror()));
4449
4450 }
4451 _timer_rsc_phase2.stop();
4452
4453 } // end redefine_single_class()
4454
4455
4456 // Increment the classRedefinedCount field in the specific InstanceKlass
4457 // and in all direct and indirect subclasses.
4458 void VM_RedefineClasses::increment_class_counter(InstanceKlass* ik) {
4459 for (ClassHierarchyIterator iter(ik); !iter.done(); iter.next()) {
4460 // Only update instanceKlasses
4461 Klass* sub = iter.klass();
4462 if (sub->is_instance_klass()) {
4463 oop class_mirror = InstanceKlass::cast(sub)->java_mirror();
4464 Klass* class_oop = java_lang_Class::as_Klass(class_mirror);
4465 int new_count = java_lang_Class::classRedefinedCount(class_mirror) + 1;
4466 java_lang_Class::set_classRedefinedCount(class_mirror, new_count);
4467
4468 if (class_oop != _the_class) {
4469 // _the_class count is printed at end of redefine_single_class()
4470 log_debug(redefine, class, subclass)("updated count in subclass=%s to %d", ik->external_name(), new_count);
4471 }
4472 }
4473 }
4474 }
4475
4476 void VM_RedefineClasses::CheckClass::do_klass(Klass* k) {
4477 bool no_old_methods = true; // be optimistic
4478
4479 // Both array and instance classes have vtables.
4480 // a vtable should never contain old or obsolete methods
4481 ResourceMark rm(_thread);
4482 if (k->vtable_length() > 0 &&
4483 !k->vtable().check_no_old_or_obsolete_entries()) {
4484 if (log_is_enabled(Trace, redefine, class, obsolete, metadata)) {
4485 log_trace(redefine, class, obsolete, metadata)
4486 ("klassVtable::check_no_old_or_obsolete_entries failure -- OLD or OBSOLETE method found -- class: %s",
4487 k->signature_name());
4488 k->vtable().dump_vtable();
4489 }
4490 no_old_methods = false;
4491 }
4492
4493 if (k->is_instance_klass()) {
4494 HandleMark hm(_thread);
4495 InstanceKlass *ik = InstanceKlass::cast(k);
4496
4497 // an itable should never contain old or obsolete methods
4498 if (ik->itable_length() > 0 &&
4499 !ik->itable().check_no_old_or_obsolete_entries()) {
4500 if (log_is_enabled(Trace, redefine, class, obsolete, metadata)) {
4501 log_trace(redefine, class, obsolete, metadata)
4502 ("klassItable::check_no_old_or_obsolete_entries failure -- OLD or OBSOLETE method found -- class: %s",
4503 ik->signature_name());
4504 ik->itable().dump_itable();
4505 }
4506 no_old_methods = false;
4507 }
4508
4509 // the constant pool cache should never contain non-deleted old or obsolete methods
4510 if (ik->constants() != NULL &&
4511 ik->constants()->cache() != NULL &&
4512 !ik->constants()->cache()->check_no_old_or_obsolete_entries()) {
4513 if (log_is_enabled(Trace, redefine, class, obsolete, metadata)) {
4514 log_trace(redefine, class, obsolete, metadata)
4515 ("cp-cache::check_no_old_or_obsolete_entries failure -- OLD or OBSOLETE method found -- class: %s",
4516 ik->signature_name());
4517 ik->constants()->cache()->dump_cache();
4518 }
4519 no_old_methods = false;
4520 }
4521 }
4522
4523 // print and fail guarantee if old methods are found.
4524 if (!no_old_methods) {
4525 if (log_is_enabled(Trace, redefine, class, obsolete, metadata)) {
4526 dump_methods();
4527 } else {
4528 log_trace(redefine, class)("Use the '-Xlog:redefine+class*:' option "
4529 "to see more info about the following guarantee() failure.");
4530 }
4531 guarantee(false, "OLD and/or OBSOLETE method(s) found");
4532 }
4533 }
4534
4535 u8 VM_RedefineClasses::next_id() {
4536 while (true) {
4537 u8 id = _id_counter;
4538 u8 next_id = id + 1;
4539 u8 result = Atomic::cmpxchg(&_id_counter, id, next_id);
4540 if (result == id) {
4541 return next_id;
4542 }
4543 }
4544 }
4545
4546 void VM_RedefineClasses::dump_methods() {
4547 int j;
4548 log_trace(redefine, class, dump)("_old_methods --");
4549 for (j = 0; j < _old_methods->length(); ++j) {
4550 LogStreamHandle(Trace, redefine, class, dump) log_stream;
4551 Method* m = _old_methods->at(j);
4552 log_stream.print("%4d (%5d) ", j, m->vtable_index());
4553 m->access_flags().print_on(&log_stream);
4554 log_stream.print(" -- ");
4555 m->print_name(&log_stream);
4556 log_stream.cr();
4557 }
4558 log_trace(redefine, class, dump)("_new_methods --");
4559 for (j = 0; j < _new_methods->length(); ++j) {
4560 LogStreamHandle(Trace, redefine, class, dump) log_stream;
4561 Method* m = _new_methods->at(j);
4562 log_stream.print("%4d (%5d) ", j, m->vtable_index());
4563 m->access_flags().print_on(&log_stream);
4564 log_stream.print(" -- ");
4565 m->print_name(&log_stream);
4566 log_stream.cr();
4567 }
4568 log_trace(redefine, class, dump)("_matching_methods --");
4569 for (j = 0; j < _matching_methods_length; ++j) {
4570 LogStreamHandle(Trace, redefine, class, dump) log_stream;
4571 Method* m = _matching_old_methods[j];
4572 log_stream.print("%4d (%5d) ", j, m->vtable_index());
4573 m->access_flags().print_on(&log_stream);
4574 log_stream.print(" -- ");
4575 m->print_name();
4576 log_stream.cr();
4577
4578 m = _matching_new_methods[j];
4579 log_stream.print(" (%5d) ", m->vtable_index());
4580 m->access_flags().print_on(&log_stream);
4581 log_stream.cr();
4582 }
4583 log_trace(redefine, class, dump)("_deleted_methods --");
4584 for (j = 0; j < _deleted_methods_length; ++j) {
4585 LogStreamHandle(Trace, redefine, class, dump) log_stream;
4586 Method* m = _deleted_methods[j];
4587 log_stream.print("%4d (%5d) ", j, m->vtable_index());
4588 m->access_flags().print_on(&log_stream);
4589 log_stream.print(" -- ");
4590 m->print_name(&log_stream);
4591 log_stream.cr();
4592 }
4593 log_trace(redefine, class, dump)("_added_methods --");
4594 for (j = 0; j < _added_methods_length; ++j) {
4595 LogStreamHandle(Trace, redefine, class, dump) log_stream;
4596 Method* m = _added_methods[j];
4597 log_stream.print("%4d (%5d) ", j, m->vtable_index());
4598 m->access_flags().print_on(&log_stream);
4599 log_stream.print(" -- ");
4600 m->print_name(&log_stream);
4601 log_stream.cr();
4602 }
4603 }
4604
4605 void VM_RedefineClasses::print_on_error(outputStream* st) const {
4606 VM_Operation::print_on_error(st);
4607 if (_the_class != NULL) {
4608 ResourceMark rm;
4609 st->print_cr(", redefining class %s", _the_class->external_name());
4610 }
4611 }