1 /*
2 * Copyright (c) 2003, 2022, 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 (log_is_enabled(Info, redefine, class, timer)) {
241 _timer_vm_op_doit.start();
242 }
243
244 #if INCLUDE_CDS
245 if (UseSharedSpaces) {
246 // Sharing is enabled so we remap the shared readonly space to
247 // shared readwrite, private just in case we need to redefine
248 // a shared class. We do the remap during the doit() phase of
249 // the safepoint to be safer.
250 if (!MetaspaceShared::remap_shared_readonly_as_readwrite()) {
251 log_info(redefine, class, load)("failed to remap shared readonly space to readwrite, private");
252 _res = JVMTI_ERROR_INTERNAL;
253 _timer_vm_op_doit.stop();
254 return;
255 }
256 }
257 #endif
258
259 // Mark methods seen on stack and everywhere else so old methods are not
260 // cleaned up if they're on the stack.
261 MetadataOnStackMark md_on_stack(/*walk_all_metadata*/true, /*redefinition_walk*/true);
262 HandleMark hm(current); // make sure any handles created are deleted
263 // before the stack walk again.
264
265 for (int i = 0; i < _class_count; i++) {
266 redefine_single_class(current, _class_defs[i].klass, _scratch_classes[i]);
267 }
268
269 // Flush all compiled code that depends on the classes redefined.
270 flush_dependent_code();
271
272 // Adjust constantpool caches and vtables for all classes
273 // that reference methods of the evolved classes.
274 // Have to do this after all classes are redefined and all methods that
275 // are redefined are marked as old.
276 AdjustAndCleanMetadata adjust_and_clean_metadata(current);
277 ClassLoaderDataGraph::classes_do(&adjust_and_clean_metadata);
278
279 // JSR-292 support
280 if (_any_class_has_resolved_methods) {
281 bool trace_name_printed = false;
282 ResolvedMethodTable::adjust_method_entries(&trace_name_printed);
283 }
284
285 // Increment flag indicating that some invariants are no longer true.
286 // See jvmtiExport.hpp for detailed explanation.
287 JvmtiExport::increment_redefinition_count();
288
289 // check_class() is optionally called for product bits, but is
290 // always called for non-product bits.
291 #ifdef PRODUCT
292 if (log_is_enabled(Trace, redefine, class, obsolete, metadata)) {
293 #endif
294 log_trace(redefine, class, obsolete, metadata)("calling check_class");
295 CheckClass check_class(current);
296 ClassLoaderDataGraph::classes_do(&check_class);
297 #ifdef PRODUCT
298 }
299 #endif
300
301 // Clean up any metadata now unreferenced while MetadataOnStackMark is set.
302 ClassLoaderDataGraph::clean_deallocate_lists(false);
303
304 _timer_vm_op_doit.stop();
305 }
306
307 void VM_RedefineClasses::doit_epilogue() {
308 unlock_classes();
309
310 // Free os::malloc allocated memory.
311 os::free(_scratch_classes);
312
313 // Reset the_class to null for error printing.
314 _the_class = NULL;
315
316 if (log_is_enabled(Info, redefine, class, timer)) {
317 // Used to have separate timers for "doit" and "all", but the timer
318 // overhead skewed the measurements.
319 julong doit_time = _timer_vm_op_doit.milliseconds();
320 julong all_time = _timer_vm_op_prologue.milliseconds() + doit_time;
321
322 log_info(redefine, class, timer)
323 ("vm_op: all=" JULONG_FORMAT " prologue=" JULONG_FORMAT " doit=" JULONG_FORMAT,
324 all_time, (julong)_timer_vm_op_prologue.milliseconds(), doit_time);
325 log_info(redefine, class, timer)
326 ("redefine_single_class: phase1=" JULONG_FORMAT " phase2=" JULONG_FORMAT,
327 (julong)_timer_rsc_phase1.milliseconds(), (julong)_timer_rsc_phase2.milliseconds());
328 }
329 }
330
331 bool VM_RedefineClasses::is_modifiable_class(oop klass_mirror) {
332 // classes for primitives cannot be redefined
333 if (java_lang_Class::is_primitive(klass_mirror)) {
334 return false;
335 }
336 Klass* k = java_lang_Class::as_Klass(klass_mirror);
337 // classes for arrays cannot be redefined
338 if (k == NULL || !k->is_instance_klass()) {
339 return false;
340 }
341
342 // Cannot redefine or retransform a hidden class.
343 if (InstanceKlass::cast(k)->is_hidden()) {
344 return false;
345 }
346 return true;
347 }
348
349 // Append the current entry at scratch_i in scratch_cp to *merge_cp_p
350 // where the end of *merge_cp_p is specified by *merge_cp_length_p. For
351 // direct CP entries, there is just the current entry to append. For
352 // indirect and double-indirect CP entries, there are zero or more
353 // referenced CP entries along with the current entry to append.
354 // Indirect and double-indirect CP entries are handled by recursive
355 // calls to append_entry() as needed. The referenced CP entries are
356 // always appended to *merge_cp_p before the referee CP entry. These
357 // referenced CP entries may already exist in *merge_cp_p in which case
358 // there is nothing extra to append and only the current entry is
359 // appended.
360 void VM_RedefineClasses::append_entry(const constantPoolHandle& scratch_cp,
361 int scratch_i, constantPoolHandle *merge_cp_p, int *merge_cp_length_p) {
362
363 // append is different depending on entry tag type
364 switch (scratch_cp->tag_at(scratch_i).value()) {
365
366 // The old verifier is implemented outside the VM. It loads classes,
367 // but does not resolve constant pool entries directly so we never
368 // see Class entries here with the old verifier. Similarly the old
369 // verifier does not like Class entries in the input constant pool.
370 // The split-verifier is implemented in the VM so it can optionally
371 // and directly resolve constant pool entries to load classes. The
372 // split-verifier can accept either Class entries or UnresolvedClass
373 // entries in the input constant pool. We revert the appended copy
374 // back to UnresolvedClass so that either verifier will be happy
375 // with the constant pool entry.
376 //
377 // this is an indirect CP entry so it needs special handling
378 case JVM_CONSTANT_Class:
379 case JVM_CONSTANT_UnresolvedClass:
380 {
381 int name_i = scratch_cp->klass_name_index_at(scratch_i);
382 int new_name_i = find_or_append_indirect_entry(scratch_cp, name_i, merge_cp_p,
383 merge_cp_length_p);
384
385 if (new_name_i != name_i) {
386 log_trace(redefine, class, constantpool)
387 ("Class entry@%d name_index change: %d to %d",
388 *merge_cp_length_p, name_i, new_name_i);
389 }
390
391 (*merge_cp_p)->temp_unresolved_klass_at_put(*merge_cp_length_p, new_name_i);
392 if (scratch_i != *merge_cp_length_p) {
393 // The new entry in *merge_cp_p is at a different index than
394 // the new entry in scratch_cp so we need to map the index values.
395 map_index(scratch_cp, scratch_i, *merge_cp_length_p);
396 }
397 (*merge_cp_length_p)++;
398 } break;
399
400 // these are direct CP entries so they can be directly appended,
401 // but double and long take two constant pool entries
402 case JVM_CONSTANT_Double: // fall through
403 case JVM_CONSTANT_Long:
404 {
405 ConstantPool::copy_entry_to(scratch_cp, scratch_i, *merge_cp_p, *merge_cp_length_p);
406
407 if (scratch_i != *merge_cp_length_p) {
408 // The new entry in *merge_cp_p is at a different index than
409 // the new entry in scratch_cp so we need to map the index values.
410 map_index(scratch_cp, scratch_i, *merge_cp_length_p);
411 }
412 (*merge_cp_length_p) += 2;
413 } break;
414
415 // these are direct CP entries so they can be directly appended
416 case JVM_CONSTANT_Float: // fall through
417 case JVM_CONSTANT_Integer: // fall through
418 case JVM_CONSTANT_Utf8: // fall through
419
420 // This was an indirect CP entry, but it has been changed into
421 // Symbol*s so this entry can be directly appended.
422 case JVM_CONSTANT_String: // fall through
423 {
424 ConstantPool::copy_entry_to(scratch_cp, scratch_i, *merge_cp_p, *merge_cp_length_p);
425
426 if (scratch_i != *merge_cp_length_p) {
427 // The new entry in *merge_cp_p is at a different index than
428 // the new entry in scratch_cp so we need to map the index values.
429 map_index(scratch_cp, scratch_i, *merge_cp_length_p);
430 }
431 (*merge_cp_length_p)++;
432 } break;
433
434 // this is an indirect CP entry so it needs special handling
435 case JVM_CONSTANT_NameAndType:
436 {
437 int name_ref_i = scratch_cp->name_ref_index_at(scratch_i);
438 int new_name_ref_i = find_or_append_indirect_entry(scratch_cp, name_ref_i, merge_cp_p,
439 merge_cp_length_p);
440
441 int signature_ref_i = scratch_cp->signature_ref_index_at(scratch_i);
442 int new_signature_ref_i = find_or_append_indirect_entry(scratch_cp, signature_ref_i,
443 merge_cp_p, merge_cp_length_p);
444
445 // If the referenced entries already exist in *merge_cp_p, then
446 // both new_name_ref_i and new_signature_ref_i will both be 0.
447 // In that case, all we are appending is the current entry.
448 if (new_name_ref_i != name_ref_i) {
449 log_trace(redefine, class, constantpool)
450 ("NameAndType entry@%d name_ref_index change: %d to %d",
451 *merge_cp_length_p, name_ref_i, new_name_ref_i);
452 }
453 if (new_signature_ref_i != signature_ref_i) {
454 log_trace(redefine, class, constantpool)
455 ("NameAndType entry@%d signature_ref_index change: %d to %d",
456 *merge_cp_length_p, signature_ref_i, new_signature_ref_i);
457 }
458
459 (*merge_cp_p)->name_and_type_at_put(*merge_cp_length_p,
460 new_name_ref_i, new_signature_ref_i);
461 if (scratch_i != *merge_cp_length_p) {
462 // The new entry in *merge_cp_p is at a different index than
463 // the new entry in scratch_cp so we need to map the index values.
464 map_index(scratch_cp, scratch_i, *merge_cp_length_p);
465 }
466 (*merge_cp_length_p)++;
467 } break;
468
469 // this is a double-indirect CP entry so it needs special handling
470 case JVM_CONSTANT_Fieldref: // fall through
471 case JVM_CONSTANT_InterfaceMethodref: // fall through
472 case JVM_CONSTANT_Methodref:
473 {
474 int klass_ref_i = scratch_cp->uncached_klass_ref_index_at(scratch_i);
475 int new_klass_ref_i = find_or_append_indirect_entry(scratch_cp, klass_ref_i,
476 merge_cp_p, merge_cp_length_p);
477
478 int name_and_type_ref_i = scratch_cp->uncached_name_and_type_ref_index_at(scratch_i);
479 int new_name_and_type_ref_i = find_or_append_indirect_entry(scratch_cp, name_and_type_ref_i,
480 merge_cp_p, merge_cp_length_p);
481
482 const char *entry_name = NULL;
483 switch (scratch_cp->tag_at(scratch_i).value()) {
484 case JVM_CONSTANT_Fieldref:
485 entry_name = "Fieldref";
486 (*merge_cp_p)->field_at_put(*merge_cp_length_p, new_klass_ref_i,
487 new_name_and_type_ref_i);
488 break;
489 case JVM_CONSTANT_InterfaceMethodref:
490 entry_name = "IFMethodref";
491 (*merge_cp_p)->interface_method_at_put(*merge_cp_length_p,
492 new_klass_ref_i, new_name_and_type_ref_i);
493 break;
494 case JVM_CONSTANT_Methodref:
495 entry_name = "Methodref";
496 (*merge_cp_p)->method_at_put(*merge_cp_length_p, new_klass_ref_i,
497 new_name_and_type_ref_i);
498 break;
499 default:
500 guarantee(false, "bad switch");
501 break;
502 }
503
504 if (klass_ref_i != new_klass_ref_i) {
505 log_trace(redefine, class, constantpool)
506 ("%s entry@%d class_index changed: %d to %d", entry_name, *merge_cp_length_p, klass_ref_i, new_klass_ref_i);
507 }
508 if (name_and_type_ref_i != new_name_and_type_ref_i) {
509 log_trace(redefine, class, constantpool)
510 ("%s entry@%d name_and_type_index changed: %d to %d",
511 entry_name, *merge_cp_length_p, name_and_type_ref_i, new_name_and_type_ref_i);
512 }
513
514 if (scratch_i != *merge_cp_length_p) {
515 // The new entry in *merge_cp_p is at a different index than
516 // the new entry in scratch_cp so we need to map the index values.
517 map_index(scratch_cp, scratch_i, *merge_cp_length_p);
518 }
519 (*merge_cp_length_p)++;
520 } break;
521
522 // this is an indirect CP entry so it needs special handling
523 case JVM_CONSTANT_MethodType:
524 {
525 int ref_i = scratch_cp->method_type_index_at(scratch_i);
526 int new_ref_i = find_or_append_indirect_entry(scratch_cp, ref_i, merge_cp_p,
527 merge_cp_length_p);
528 if (new_ref_i != ref_i) {
529 log_trace(redefine, class, constantpool)
530 ("MethodType entry@%d ref_index change: %d to %d", *merge_cp_length_p, ref_i, new_ref_i);
531 }
532 (*merge_cp_p)->method_type_index_at_put(*merge_cp_length_p, new_ref_i);
533 if (scratch_i != *merge_cp_length_p) {
534 // The new entry in *merge_cp_p is at a different index than
535 // the new entry in scratch_cp so we need to map the index values.
536 map_index(scratch_cp, scratch_i, *merge_cp_length_p);
537 }
538 (*merge_cp_length_p)++;
539 } break;
540
541 // this is an indirect CP entry so it needs special handling
542 case JVM_CONSTANT_MethodHandle:
543 {
544 int ref_kind = scratch_cp->method_handle_ref_kind_at(scratch_i);
545 int ref_i = scratch_cp->method_handle_index_at(scratch_i);
546 int new_ref_i = find_or_append_indirect_entry(scratch_cp, ref_i, merge_cp_p,
547 merge_cp_length_p);
548 if (new_ref_i != ref_i) {
549 log_trace(redefine, class, constantpool)
550 ("MethodHandle entry@%d ref_index change: %d to %d", *merge_cp_length_p, ref_i, new_ref_i);
551 }
552 (*merge_cp_p)->method_handle_index_at_put(*merge_cp_length_p, ref_kind, new_ref_i);
553 if (scratch_i != *merge_cp_length_p) {
554 // The new entry in *merge_cp_p is at a different index than
555 // the new entry in scratch_cp so we need to map the index values.
556 map_index(scratch_cp, scratch_i, *merge_cp_length_p);
557 }
558 (*merge_cp_length_p)++;
559 } break;
560
561 // this is an indirect CP entry so it needs special handling
562 case JVM_CONSTANT_Dynamic: // fall through
563 case JVM_CONSTANT_InvokeDynamic:
564 {
565 // Index of the bootstrap specifier in the operands array
566 int old_bs_i = scratch_cp->bootstrap_methods_attribute_index(scratch_i);
567 int new_bs_i = find_or_append_operand(scratch_cp, old_bs_i, merge_cp_p,
568 merge_cp_length_p);
569 // The bootstrap method NameAndType_info index
570 int old_ref_i = scratch_cp->bootstrap_name_and_type_ref_index_at(scratch_i);
571 int new_ref_i = find_or_append_indirect_entry(scratch_cp, old_ref_i, merge_cp_p,
572 merge_cp_length_p);
573 if (new_bs_i != old_bs_i) {
574 log_trace(redefine, class, constantpool)
575 ("Dynamic entry@%d bootstrap_method_attr_index change: %d to %d",
576 *merge_cp_length_p, old_bs_i, new_bs_i);
577 }
578 if (new_ref_i != old_ref_i) {
579 log_trace(redefine, class, constantpool)
580 ("Dynamic entry@%d name_and_type_index change: %d to %d", *merge_cp_length_p, old_ref_i, new_ref_i);
581 }
582
583 if (scratch_cp->tag_at(scratch_i).is_dynamic_constant())
584 (*merge_cp_p)->dynamic_constant_at_put(*merge_cp_length_p, new_bs_i, new_ref_i);
585 else
586 (*merge_cp_p)->invoke_dynamic_at_put(*merge_cp_length_p, new_bs_i, new_ref_i);
587 if (scratch_i != *merge_cp_length_p) {
588 // The new entry in *merge_cp_p is at a different index than
589 // the new entry in scratch_cp so we need to map the index values.
590 map_index(scratch_cp, scratch_i, *merge_cp_length_p);
591 }
592 (*merge_cp_length_p)++;
593 } break;
594
595 // At this stage, Class or UnresolvedClass could be in scratch_cp, but not
596 // ClassIndex
597 case JVM_CONSTANT_ClassIndex: // fall through
598
599 // Invalid is used as the tag for the second constant pool entry
600 // occupied by JVM_CONSTANT_Double or JVM_CONSTANT_Long. It should
601 // not be seen by itself.
602 case JVM_CONSTANT_Invalid: // fall through
603
604 // At this stage, String could be here, but not StringIndex
605 case JVM_CONSTANT_StringIndex: // fall through
606
607 // At this stage JVM_CONSTANT_UnresolvedClassInError should not be
608 // here
609 case JVM_CONSTANT_UnresolvedClassInError: // fall through
610
611 default:
612 {
613 // leave a breadcrumb
614 jbyte bad_value = scratch_cp->tag_at(scratch_i).value();
615 ShouldNotReachHere();
616 } break;
617 } // end switch tag value
618 } // end append_entry()
619
620
621 int VM_RedefineClasses::find_or_append_indirect_entry(const constantPoolHandle& scratch_cp,
622 int ref_i, constantPoolHandle *merge_cp_p, int *merge_cp_length_p) {
623
624 int new_ref_i = ref_i;
625 bool match = (ref_i < *merge_cp_length_p) &&
626 scratch_cp->compare_entry_to(ref_i, *merge_cp_p, ref_i);
627
628 if (!match) {
629 // forward reference in *merge_cp_p or not a direct match
630 int found_i = scratch_cp->find_matching_entry(ref_i, *merge_cp_p);
631 if (found_i != 0) {
632 guarantee(found_i != ref_i, "compare_entry_to() and find_matching_entry() do not agree");
633 // Found a matching entry somewhere else in *merge_cp_p so just need a mapping entry.
634 new_ref_i = found_i;
635 map_index(scratch_cp, ref_i, found_i);
636 } else {
637 // no match found so we have to append this entry to *merge_cp_p
638 append_entry(scratch_cp, ref_i, merge_cp_p, merge_cp_length_p);
639 // The above call to append_entry() can only append one entry
640 // so the post call query of *merge_cp_length_p is only for
641 // the sake of consistency.
642 new_ref_i = *merge_cp_length_p - 1;
643 }
644 }
645
646 return new_ref_i;
647 } // end find_or_append_indirect_entry()
648
649
650 // Append a bootstrap specifier into the merge_cp operands that is semantically equal
651 // to the scratch_cp operands bootstrap specifier passed by the old_bs_i index.
652 // Recursively append new merge_cp entries referenced by the new bootstrap specifier.
653 void VM_RedefineClasses::append_operand(const constantPoolHandle& scratch_cp, int old_bs_i,
654 constantPoolHandle *merge_cp_p, int *merge_cp_length_p) {
655
656 int old_ref_i = scratch_cp->operand_bootstrap_method_ref_index_at(old_bs_i);
657 int new_ref_i = find_or_append_indirect_entry(scratch_cp, old_ref_i, merge_cp_p,
658 merge_cp_length_p);
659 if (new_ref_i != old_ref_i) {
660 log_trace(redefine, class, constantpool)
661 ("operands entry@%d bootstrap method ref_index change: %d to %d", _operands_cur_length, old_ref_i, new_ref_i);
662 }
663
664 Array<u2>* merge_ops = (*merge_cp_p)->operands();
665 int new_bs_i = _operands_cur_length;
666 // We have _operands_cur_length == 0 when the merge_cp operands is empty yet.
667 // However, the operand_offset_at(0) was set in the extend_operands() call.
668 int new_base = (new_bs_i == 0) ? (*merge_cp_p)->operand_offset_at(0)
669 : (*merge_cp_p)->operand_next_offset_at(new_bs_i - 1);
670 int argc = scratch_cp->operand_argument_count_at(old_bs_i);
671
672 ConstantPool::operand_offset_at_put(merge_ops, _operands_cur_length, new_base);
673 merge_ops->at_put(new_base++, new_ref_i);
674 merge_ops->at_put(new_base++, argc);
675
676 for (int i = 0; i < argc; i++) {
677 int old_arg_ref_i = scratch_cp->operand_argument_index_at(old_bs_i, i);
678 int new_arg_ref_i = find_or_append_indirect_entry(scratch_cp, old_arg_ref_i, merge_cp_p,
679 merge_cp_length_p);
680 merge_ops->at_put(new_base++, new_arg_ref_i);
681 if (new_arg_ref_i != old_arg_ref_i) {
682 log_trace(redefine, class, constantpool)
683 ("operands entry@%d bootstrap method argument ref_index change: %d to %d",
684 _operands_cur_length, old_arg_ref_i, new_arg_ref_i);
685 }
686 }
687 if (old_bs_i != _operands_cur_length) {
688 // The bootstrap specifier in *merge_cp_p is at a different index than
689 // that in scratch_cp so we need to map the index values.
690 map_operand_index(old_bs_i, new_bs_i);
691 }
692 _operands_cur_length++;
693 } // end append_operand()
694
695
696 int VM_RedefineClasses::find_or_append_operand(const constantPoolHandle& scratch_cp,
697 int old_bs_i, constantPoolHandle *merge_cp_p, int *merge_cp_length_p) {
698
699 int new_bs_i = old_bs_i; // bootstrap specifier index
700 bool match = (old_bs_i < _operands_cur_length) &&
701 scratch_cp->compare_operand_to(old_bs_i, *merge_cp_p, old_bs_i);
702
703 if (!match) {
704 // forward reference in *merge_cp_p or not a direct match
705 int found_i = scratch_cp->find_matching_operand(old_bs_i, *merge_cp_p,
706 _operands_cur_length);
707 if (found_i != -1) {
708 guarantee(found_i != old_bs_i, "compare_operand_to() and find_matching_operand() disagree");
709 // found a matching operand somewhere else in *merge_cp_p so just need a mapping
710 new_bs_i = found_i;
711 map_operand_index(old_bs_i, found_i);
712 } else {
713 // no match found so we have to append this bootstrap specifier to *merge_cp_p
714 append_operand(scratch_cp, old_bs_i, merge_cp_p, merge_cp_length_p);
715 new_bs_i = _operands_cur_length - 1;
716 }
717 }
718 return new_bs_i;
719 } // end find_or_append_operand()
720
721
722 void VM_RedefineClasses::finalize_operands_merge(const constantPoolHandle& merge_cp, TRAPS) {
723 if (merge_cp->operands() == NULL) {
724 return;
725 }
726 // Shrink the merge_cp operands
727 merge_cp->shrink_operands(_operands_cur_length, CHECK);
728
729 if (log_is_enabled(Trace, redefine, class, constantpool)) {
730 // don't want to loop unless we are tracing
731 int count = 0;
732 for (int i = 1; i < _operands_index_map_p->length(); i++) {
733 int value = _operands_index_map_p->at(i);
734 if (value != -1) {
735 log_trace(redefine, class, constantpool)("operands_index_map[%d]: old=%d new=%d", count, i, value);
736 count++;
737 }
738 }
739 }
740 // Clean-up
741 _operands_index_map_p = NULL;
742 _operands_cur_length = 0;
743 _operands_index_map_count = 0;
744 } // end finalize_operands_merge()
745
746 // Symbol* comparator for qsort
747 // The caller must have an active ResourceMark.
748 static int symcmp(const void* a, const void* b) {
749 char* astr = (*(Symbol**)a)->as_C_string();
750 char* bstr = (*(Symbol**)b)->as_C_string();
751 return strcmp(astr, bstr);
752 }
753
754 // The caller must have an active ResourceMark.
755 static jvmtiError check_attribute_arrays(const char* attr_name,
756 InstanceKlass* the_class, InstanceKlass* scratch_class,
757 Array<u2>* the_array, Array<u2>* scr_array) {
758 bool the_array_exists = the_array != Universe::the_empty_short_array();
759 bool scr_array_exists = scr_array != Universe::the_empty_short_array();
760
761 int array_len = the_array->length();
762 if (the_array_exists && scr_array_exists) {
763 if (array_len != scr_array->length()) {
764 log_trace(redefine, class)
765 ("redefined class %s attribute change error: %s len=%d changed to len=%d",
766 the_class->external_name(), attr_name, array_len, scr_array->length());
767 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_CLASS_ATTRIBUTE_CHANGED;
768 }
769
770 // The order of entries in the attribute array is not specified so we
771 // have to explicitly check for the same contents. We do this by copying
772 // the referenced symbols into their own arrays, sorting them and then
773 // comparing each element pair.
774
775 Symbol** the_syms = NEW_RESOURCE_ARRAY_RETURN_NULL(Symbol*, array_len);
776 Symbol** scr_syms = NEW_RESOURCE_ARRAY_RETURN_NULL(Symbol*, array_len);
777
778 if (the_syms == NULL || scr_syms == NULL) {
779 return JVMTI_ERROR_OUT_OF_MEMORY;
780 }
781
782 for (int i = 0; i < array_len; i++) {
783 int the_cp_index = the_array->at(i);
784 int scr_cp_index = scr_array->at(i);
785 the_syms[i] = the_class->constants()->klass_name_at(the_cp_index);
786 scr_syms[i] = scratch_class->constants()->klass_name_at(scr_cp_index);
787 }
788
789 qsort(the_syms, array_len, sizeof(Symbol*), symcmp);
790 qsort(scr_syms, array_len, sizeof(Symbol*), symcmp);
791
792 for (int i = 0; i < array_len; i++) {
793 if (the_syms[i] != scr_syms[i]) {
794 log_info(redefine, class)
795 ("redefined class %s attribute change error: %s[%d]: %s changed to %s",
796 the_class->external_name(), attr_name, i,
797 the_syms[i]->as_C_string(), scr_syms[i]->as_C_string());
798 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_CLASS_ATTRIBUTE_CHANGED;
799 }
800 }
801 } else if (the_array_exists ^ scr_array_exists) {
802 const char* action_str = (the_array_exists) ? "removed" : "added";
803 log_info(redefine, class)
804 ("redefined class %s attribute change error: %s attribute %s",
805 the_class->external_name(), attr_name, action_str);
806 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_CLASS_ATTRIBUTE_CHANGED;
807 }
808 return JVMTI_ERROR_NONE;
809 }
810
811 static jvmtiError check_nest_attributes(InstanceKlass* the_class,
812 InstanceKlass* scratch_class) {
813 // Check whether the class NestHost attribute has been changed.
814 Thread* thread = Thread::current();
815 ResourceMark rm(thread);
816 u2 the_nest_host_idx = the_class->nest_host_index();
817 u2 scr_nest_host_idx = scratch_class->nest_host_index();
818
819 if (the_nest_host_idx != 0 && scr_nest_host_idx != 0) {
820 Symbol* the_sym = the_class->constants()->klass_name_at(the_nest_host_idx);
821 Symbol* scr_sym = scratch_class->constants()->klass_name_at(scr_nest_host_idx);
822 if (the_sym != scr_sym) {
823 log_info(redefine, class, nestmates)
824 ("redefined class %s attribute change error: NestHost class: %s replaced with: %s",
825 the_class->external_name(), the_sym->as_C_string(), scr_sym->as_C_string());
826 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_CLASS_ATTRIBUTE_CHANGED;
827 }
828 } else if ((the_nest_host_idx == 0) ^ (scr_nest_host_idx == 0)) {
829 const char* action_str = (the_nest_host_idx != 0) ? "removed" : "added";
830 log_info(redefine, class, nestmates)
831 ("redefined class %s attribute change error: NestHost attribute %s",
832 the_class->external_name(), action_str);
833 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_CLASS_ATTRIBUTE_CHANGED;
834 }
835
836 // Check whether the class NestMembers attribute has been changed.
837 return check_attribute_arrays("NestMembers",
838 the_class, scratch_class,
839 the_class->nest_members(),
840 scratch_class->nest_members());
841 }
842
843 // Return an error status if the class Record attribute was changed.
844 static jvmtiError check_record_attribute(InstanceKlass* the_class, InstanceKlass* scratch_class) {
845 // Get lists of record components.
846 Array<RecordComponent*>* the_record = the_class->record_components();
847 Array<RecordComponent*>* scr_record = scratch_class->record_components();
848 bool the_record_exists = the_record != NULL;
849 bool scr_record_exists = scr_record != NULL;
850
851 if (the_record_exists && scr_record_exists) {
852 int the_num_components = the_record->length();
853 int scr_num_components = scr_record->length();
854 if (the_num_components != scr_num_components) {
855 log_info(redefine, class, record)
856 ("redefined class %s attribute change error: Record num_components=%d changed to num_components=%d",
857 the_class->external_name(), the_num_components, scr_num_components);
858 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_CLASS_ATTRIBUTE_CHANGED;
859 }
860
861 // Compare each field in each record component.
862 ConstantPool* the_cp = the_class->constants();
863 ConstantPool* scr_cp = scratch_class->constants();
864 for (int x = 0; x < the_num_components; x++) {
865 RecordComponent* the_component = the_record->at(x);
866 RecordComponent* scr_component = scr_record->at(x);
867 const Symbol* const the_name = the_cp->symbol_at(the_component->name_index());
868 const Symbol* const scr_name = scr_cp->symbol_at(scr_component->name_index());
869 const Symbol* const the_descr = the_cp->symbol_at(the_component->descriptor_index());
870 const Symbol* const scr_descr = scr_cp->symbol_at(scr_component->descriptor_index());
871 if (the_name != scr_name || the_descr != scr_descr) {
872 log_info(redefine, class, record)
873 ("redefined class %s attribute change error: Record name_index, descriptor_index, and/or attributes_count changed",
874 the_class->external_name());
875 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_CLASS_ATTRIBUTE_CHANGED;
876 }
877
878 int the_gen_sig = the_component->generic_signature_index();
879 int scr_gen_sig = scr_component->generic_signature_index();
880 const Symbol* const the_gen_sig_sym = (the_gen_sig == 0 ? NULL :
881 the_cp->symbol_at(the_component->generic_signature_index()));
882 const Symbol* const scr_gen_sig_sym = (scr_gen_sig == 0 ? NULL :
883 scr_cp->symbol_at(scr_component->generic_signature_index()));
884 if (the_gen_sig_sym != scr_gen_sig_sym) {
885 log_info(redefine, class, record)
886 ("redefined class %s attribute change error: Record generic_signature attribute changed",
887 the_class->external_name());
888 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_CLASS_ATTRIBUTE_CHANGED;
889 }
890
891 // It's okay if a record component's annotations were changed.
892 }
893
894 } else if (the_record_exists ^ scr_record_exists) {
895 const char* action_str = (the_record_exists) ? "removed" : "added";
896 log_info(redefine, class, record)
897 ("redefined class %s attribute change error: Record attribute %s",
898 the_class->external_name(), action_str);
899 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_CLASS_ATTRIBUTE_CHANGED;
900 }
901
902 return JVMTI_ERROR_NONE;
903 }
904
905
906 static jvmtiError check_permitted_subclasses_attribute(InstanceKlass* the_class,
907 InstanceKlass* scratch_class) {
908 Thread* thread = Thread::current();
909 ResourceMark rm(thread);
910
911 // Check whether the class PermittedSubclasses attribute has been changed.
912 return check_attribute_arrays("PermittedSubclasses",
913 the_class, scratch_class,
914 the_class->permitted_subclasses(),
915 scratch_class->permitted_subclasses());
916 }
917
918 static bool can_add_or_delete(Method* m) {
919 // Compatibility mode
920 return (AllowRedefinitionToAddDeleteMethods &&
921 (m->is_private() && (m->is_static() || m->is_final())));
922 }
923
924 jvmtiError VM_RedefineClasses::compare_and_normalize_class_versions(
925 InstanceKlass* the_class,
926 InstanceKlass* scratch_class) {
927 int i;
928
929 // Check superclasses, or rather their names, since superclasses themselves can be
930 // requested to replace.
931 // Check for NULL superclass first since this might be java.lang.Object
932 if (the_class->super() != scratch_class->super() &&
933 (the_class->super() == NULL || scratch_class->super() == NULL ||
934 the_class->super()->name() !=
935 scratch_class->super()->name())) {
936 log_info(redefine, class, normalize)
937 ("redefined class %s superclass change error: superclass changed from %s to %s.",
938 the_class->external_name(),
939 the_class->super() == NULL ? "NULL" : the_class->super()->external_name(),
940 scratch_class->super() == NULL ? "NULL" : scratch_class->super()->external_name());
941 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_HIERARCHY_CHANGED;
942 }
943
944 // Check if the number, names and order of directly implemented interfaces are the same.
945 // I think in principle we should just check if the sets of names of directly implemented
946 // interfaces are the same, i.e. the order of declaration (which, however, if changed in the
947 // .java file, also changes in .class file) should not matter. However, comparing sets is
948 // technically a bit more difficult, and, more importantly, I am not sure at present that the
949 // order of interfaces does not matter on the implementation level, i.e. that the VM does not
950 // rely on it somewhere.
951 Array<InstanceKlass*>* k_interfaces = the_class->local_interfaces();
952 Array<InstanceKlass*>* k_new_interfaces = scratch_class->local_interfaces();
953 int n_intfs = k_interfaces->length();
954 if (n_intfs != k_new_interfaces->length()) {
955 log_info(redefine, class, normalize)
956 ("redefined class %s interfaces change error: number of implemented interfaces changed from %d to %d.",
957 the_class->external_name(), n_intfs, k_new_interfaces->length());
958 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_HIERARCHY_CHANGED;
959 }
960 for (i = 0; i < n_intfs; i++) {
961 if (k_interfaces->at(i)->name() !=
962 k_new_interfaces->at(i)->name()) {
963 log_info(redefine, class, normalize)
964 ("redefined class %s interfaces change error: interface changed from %s to %s.",
965 the_class->external_name(),
966 k_interfaces->at(i)->external_name(), k_new_interfaces->at(i)->external_name());
967 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_HIERARCHY_CHANGED;
968 }
969 }
970
971 // Check whether class is in the error init state.
972 if (the_class->is_in_error_state()) {
973 log_info(redefine, class, normalize)
974 ("redefined class %s is in error init state.", the_class->external_name());
975 // TBD #5057930: special error code is needed in 1.6
976 return JVMTI_ERROR_INVALID_CLASS;
977 }
978
979 // Check whether the nest-related attributes have been changed.
980 jvmtiError err = check_nest_attributes(the_class, scratch_class);
981 if (err != JVMTI_ERROR_NONE) {
982 return err;
983 }
984
985 // Check whether the Record attribute has been changed.
986 err = check_record_attribute(the_class, scratch_class);
987 if (err != JVMTI_ERROR_NONE) {
988 return err;
989 }
990
991 // Check whether the PermittedSubclasses attribute has been changed.
992 err = check_permitted_subclasses_attribute(the_class, scratch_class);
993 if (err != JVMTI_ERROR_NONE) {
994 return err;
995 }
996
997 // Check whether class modifiers are the same.
998 jushort old_flags = (jushort) the_class->access_flags().get_flags();
999 jushort new_flags = (jushort) scratch_class->access_flags().get_flags();
1000 if (old_flags != new_flags) {
1001 log_info(redefine, class, normalize)
1002 ("redefined class %s modifiers change error: modifiers changed from %d to %d.",
1003 the_class->external_name(), old_flags, new_flags);
1004 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_CLASS_MODIFIERS_CHANGED;
1005 }
1006
1007 // Check if the number, names, types and order of fields declared in these classes
1008 // are the same.
1009 JavaFieldStream old_fs(the_class);
1010 JavaFieldStream new_fs(scratch_class);
1011 for (; !old_fs.done() && !new_fs.done(); old_fs.next(), new_fs.next()) {
1012 // name and signature
1013 Symbol* name_sym1 = the_class->constants()->symbol_at(old_fs.name_index());
1014 Symbol* sig_sym1 = the_class->constants()->symbol_at(old_fs.signature_index());
1015 Symbol* name_sym2 = scratch_class->constants()->symbol_at(new_fs.name_index());
1016 Symbol* sig_sym2 = scratch_class->constants()->symbol_at(new_fs.signature_index());
1017 if (name_sym1 != name_sym2 || sig_sym1 != sig_sym2) {
1018 log_info(redefine, class, normalize)
1019 ("redefined class %s fields change error: field %s %s changed to %s %s.",
1020 the_class->external_name(),
1021 sig_sym1->as_C_string(), name_sym1->as_C_string(),
1022 sig_sym2->as_C_string(), name_sym2->as_C_string());
1023 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_SCHEMA_CHANGED;
1024 }
1025 // offset
1026 if (old_fs.offset() != new_fs.offset()) {
1027 log_info(redefine, class, normalize)
1028 ("redefined class %s field %s change error: offset changed from %d to %d.",
1029 the_class->external_name(), name_sym2->as_C_string(), old_fs.offset(), new_fs.offset());
1030 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_SCHEMA_CHANGED;
1031 }
1032 // access
1033 old_flags = old_fs.access_flags().as_short();
1034 new_flags = new_fs.access_flags().as_short();
1035 if ((old_flags ^ new_flags) & JVM_RECOGNIZED_FIELD_MODIFIERS) {
1036 log_info(redefine, class, normalize)
1037 ("redefined class %s field %s change error: modifiers changed from %d to %d.",
1038 the_class->external_name(), name_sym2->as_C_string(), old_flags, new_flags);
1039 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_SCHEMA_CHANGED;
1040 }
1041 }
1042
1043 // If both streams aren't done then we have a differing number of
1044 // fields.
1045 if (!old_fs.done() || !new_fs.done()) {
1046 const char* action = old_fs.done() ? "added" : "deleted";
1047 log_info(redefine, class, normalize)
1048 ("redefined class %s fields change error: some fields were %s.",
1049 the_class->external_name(), action);
1050 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_SCHEMA_CHANGED;
1051 }
1052
1053 // Do a parallel walk through the old and new methods. Detect
1054 // cases where they match (exist in both), have been added in
1055 // the new methods, or have been deleted (exist only in the
1056 // old methods). The class file parser places methods in order
1057 // by method name, but does not order overloaded methods by
1058 // signature. In order to determine what fate befell the methods,
1059 // this code places the overloaded new methods that have matching
1060 // old methods in the same order as the old methods and places
1061 // new overloaded methods at the end of overloaded methods of
1062 // that name. The code for this order normalization is adapted
1063 // from the algorithm used in InstanceKlass::find_method().
1064 // Since we are swapping out of order entries as we find them,
1065 // we only have to search forward through the overloaded methods.
1066 // Methods which are added and have the same name as an existing
1067 // method (but different signature) will be put at the end of
1068 // the methods with that name, and the name mismatch code will
1069 // handle them.
1070 Array<Method*>* k_old_methods(the_class->methods());
1071 Array<Method*>* k_new_methods(scratch_class->methods());
1072 int n_old_methods = k_old_methods->length();
1073 int n_new_methods = k_new_methods->length();
1074 Thread* thread = Thread::current();
1075
1076 int ni = 0;
1077 int oi = 0;
1078 while (true) {
1079 Method* k_old_method;
1080 Method* k_new_method;
1081 enum { matched, added, deleted, undetermined } method_was = undetermined;
1082
1083 if (oi >= n_old_methods) {
1084 if (ni >= n_new_methods) {
1085 break; // we've looked at everything, done
1086 }
1087 // New method at the end
1088 k_new_method = k_new_methods->at(ni);
1089 method_was = added;
1090 } else if (ni >= n_new_methods) {
1091 // Old method, at the end, is deleted
1092 k_old_method = k_old_methods->at(oi);
1093 method_was = deleted;
1094 } else {
1095 // There are more methods in both the old and new lists
1096 k_old_method = k_old_methods->at(oi);
1097 k_new_method = k_new_methods->at(ni);
1098 if (k_old_method->name() != k_new_method->name()) {
1099 // Methods are sorted by method name, so a mismatch means added
1100 // or deleted
1101 if (k_old_method->name()->fast_compare(k_new_method->name()) > 0) {
1102 method_was = added;
1103 } else {
1104 method_was = deleted;
1105 }
1106 } else if (k_old_method->signature() == k_new_method->signature()) {
1107 // Both the name and signature match
1108 method_was = matched;
1109 } else {
1110 // The name matches, but the signature doesn't, which means we have to
1111 // search forward through the new overloaded methods.
1112 int nj; // outside the loop for post-loop check
1113 for (nj = ni + 1; nj < n_new_methods; nj++) {
1114 Method* m = k_new_methods->at(nj);
1115 if (k_old_method->name() != m->name()) {
1116 // reached another method name so no more overloaded methods
1117 method_was = deleted;
1118 break;
1119 }
1120 if (k_old_method->signature() == m->signature()) {
1121 // found a match so swap the methods
1122 k_new_methods->at_put(ni, m);
1123 k_new_methods->at_put(nj, k_new_method);
1124 k_new_method = m;
1125 method_was = matched;
1126 break;
1127 }
1128 }
1129
1130 if (nj >= n_new_methods) {
1131 // reached the end without a match; so method was deleted
1132 method_was = deleted;
1133 }
1134 }
1135 }
1136
1137 switch (method_was) {
1138 case matched:
1139 // methods match, be sure modifiers do too
1140 old_flags = (jushort) k_old_method->access_flags().get_flags();
1141 new_flags = (jushort) k_new_method->access_flags().get_flags();
1142 if ((old_flags ^ new_flags) & ~(JVM_ACC_NATIVE)) {
1143 log_info(redefine, class, normalize)
1144 ("redefined class %s method %s modifiers error: modifiers changed from %d to %d",
1145 the_class->external_name(), k_old_method->name_and_sig_as_C_string(), old_flags, new_flags);
1146 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_METHOD_MODIFIERS_CHANGED;
1147 }
1148 {
1149 u2 new_num = k_new_method->method_idnum();
1150 u2 old_num = k_old_method->method_idnum();
1151 if (new_num != old_num) {
1152 Method* idnum_owner = scratch_class->method_with_idnum(old_num);
1153 if (idnum_owner != NULL) {
1154 // There is already a method assigned this idnum -- switch them
1155 // Take current and original idnum from the new_method
1156 idnum_owner->set_method_idnum(new_num);
1157 idnum_owner->set_orig_method_idnum(k_new_method->orig_method_idnum());
1158 }
1159 // Take current and original idnum from the old_method
1160 k_new_method->set_method_idnum(old_num);
1161 k_new_method->set_orig_method_idnum(k_old_method->orig_method_idnum());
1162 if (thread->has_pending_exception()) {
1163 return JVMTI_ERROR_OUT_OF_MEMORY;
1164 }
1165 }
1166 }
1167 log_trace(redefine, class, normalize)
1168 ("Method matched: new: %s [%d] == old: %s [%d]",
1169 k_new_method->name_and_sig_as_C_string(), ni, k_old_method->name_and_sig_as_C_string(), oi);
1170 // advance to next pair of methods
1171 ++oi;
1172 ++ni;
1173 break;
1174 case added:
1175 // method added, see if it is OK
1176 if (!can_add_or_delete(k_new_method)) {
1177 log_info(redefine, class, normalize)
1178 ("redefined class %s methods error: added method: %s [%d]",
1179 the_class->external_name(), k_new_method->name_and_sig_as_C_string(), ni);
1180 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_METHOD_ADDED;
1181 }
1182 {
1183 u2 num = the_class->next_method_idnum();
1184 if (num == ConstMethod::UNSET_IDNUM) {
1185 // cannot add any more methods
1186 log_info(redefine, class, normalize)
1187 ("redefined class %s methods error: can't create ID for new method %s [%d]",
1188 the_class->external_name(), k_new_method->name_and_sig_as_C_string(), ni);
1189 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_METHOD_ADDED;
1190 }
1191 u2 new_num = k_new_method->method_idnum();
1192 Method* idnum_owner = scratch_class->method_with_idnum(num);
1193 if (idnum_owner != NULL) {
1194 // There is already a method assigned this idnum -- switch them
1195 // Take current and original idnum from the new_method
1196 idnum_owner->set_method_idnum(new_num);
1197 idnum_owner->set_orig_method_idnum(k_new_method->orig_method_idnum());
1198 }
1199 k_new_method->set_method_idnum(num);
1200 k_new_method->set_orig_method_idnum(num);
1201 if (thread->has_pending_exception()) {
1202 return JVMTI_ERROR_OUT_OF_MEMORY;
1203 }
1204 }
1205 log_trace(redefine, class, normalize)
1206 ("Method added: new: %s [%d]", k_new_method->name_and_sig_as_C_string(), ni);
1207 ++ni; // advance to next new method
1208 break;
1209 case deleted:
1210 // method deleted, see if it is OK
1211 if (!can_add_or_delete(k_old_method)) {
1212 log_info(redefine, class, normalize)
1213 ("redefined class %s methods error: deleted method %s [%d]",
1214 the_class->external_name(), k_old_method->name_and_sig_as_C_string(), oi);
1215 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_METHOD_DELETED;
1216 }
1217 log_trace(redefine, class, normalize)
1218 ("Method deleted: old: %s [%d]", k_old_method->name_and_sig_as_C_string(), oi);
1219 ++oi; // advance to next old method
1220 break;
1221 default:
1222 ShouldNotReachHere();
1223 }
1224 }
1225
1226 return JVMTI_ERROR_NONE;
1227 }
1228
1229
1230 // Find new constant pool index value for old constant pool index value
1231 // by searching the index map. Returns zero (0) if there is no mapped
1232 // value for the old constant pool index.
1233 int VM_RedefineClasses::find_new_index(int old_index) {
1234 if (_index_map_count == 0) {
1235 // map is empty so nothing can be found
1236 return 0;
1237 }
1238
1239 if (old_index < 1 || old_index >= _index_map_p->length()) {
1240 // The old_index is out of range so it is not mapped. This should
1241 // not happen in regular constant pool merging use, but it can
1242 // happen if a corrupt annotation is processed.
1243 return 0;
1244 }
1245
1246 int value = _index_map_p->at(old_index);
1247 if (value == -1) {
1248 // the old_index is not mapped
1249 return 0;
1250 }
1251
1252 return value;
1253 } // end find_new_index()
1254
1255
1256 // Find new bootstrap specifier index value for old bootstrap specifier index
1257 // value by searching the index map. Returns unused index (-1) if there is
1258 // no mapped value for the old bootstrap specifier index.
1259 int VM_RedefineClasses::find_new_operand_index(int old_index) {
1260 if (_operands_index_map_count == 0) {
1261 // map is empty so nothing can be found
1262 return -1;
1263 }
1264
1265 if (old_index == -1 || old_index >= _operands_index_map_p->length()) {
1266 // The old_index is out of range so it is not mapped.
1267 // This should not happen in regular constant pool merging use.
1268 return -1;
1269 }
1270
1271 int value = _operands_index_map_p->at(old_index);
1272 if (value == -1) {
1273 // the old_index is not mapped
1274 return -1;
1275 }
1276
1277 return value;
1278 } // end find_new_operand_index()
1279
1280
1281 // Returns true if the current mismatch is due to a resolved/unresolved
1282 // class pair. Otherwise, returns false.
1283 bool VM_RedefineClasses::is_unresolved_class_mismatch(const constantPoolHandle& cp1,
1284 int index1, const constantPoolHandle& cp2, int index2) {
1285
1286 jbyte t1 = cp1->tag_at(index1).value();
1287 if (t1 != JVM_CONSTANT_Class && t1 != JVM_CONSTANT_UnresolvedClass) {
1288 return false; // wrong entry type; not our special case
1289 }
1290
1291 jbyte t2 = cp2->tag_at(index2).value();
1292 if (t2 != JVM_CONSTANT_Class && t2 != JVM_CONSTANT_UnresolvedClass) {
1293 return false; // wrong entry type; not our special case
1294 }
1295
1296 if (t1 == t2) {
1297 return false; // not a mismatch; not our special case
1298 }
1299
1300 char *s1 = cp1->klass_name_at(index1)->as_C_string();
1301 char *s2 = cp2->klass_name_at(index2)->as_C_string();
1302 if (strcmp(s1, s2) != 0) {
1303 return false; // strings don't match; not our special case
1304 }
1305
1306 return true; // made it through the gauntlet; this is our special case
1307 } // end is_unresolved_class_mismatch()
1308
1309
1310 // The bug 6214132 caused the verification to fail.
1311 // 1. What's done in RedefineClasses() before verification:
1312 // a) A reference to the class being redefined (_the_class) and a
1313 // reference to new version of the class (_scratch_class) are
1314 // saved here for use during the bytecode verification phase of
1315 // RedefineClasses.
1316 // b) The _java_mirror field from _the_class is copied to the
1317 // _java_mirror field in _scratch_class. This means that a jclass
1318 // returned for _the_class or _scratch_class will refer to the
1319 // same Java mirror. The verifier will see the "one true mirror"
1320 // for the class being verified.
1321 // 2. See comments in JvmtiThreadState for what is done during verification.
1322
1323 class RedefineVerifyMark : public StackObj {
1324 private:
1325 JvmtiThreadState* _state;
1326 Klass* _scratch_class;
1327 Handle _scratch_mirror;
1328
1329 public:
1330
1331 RedefineVerifyMark(Klass* the_class, Klass* scratch_class,
1332 JvmtiThreadState* state) : _state(state), _scratch_class(scratch_class)
1333 {
1334 _state->set_class_versions_map(the_class, scratch_class);
1335 _scratch_mirror = Handle(_state->get_thread(), _scratch_class->java_mirror());
1336 _scratch_class->replace_java_mirror(the_class->java_mirror());
1337 }
1338
1339 ~RedefineVerifyMark() {
1340 // Restore the scratch class's mirror, so when scratch_class is removed
1341 // the correct mirror pointing to it can be cleared.
1342 _scratch_class->replace_java_mirror(_scratch_mirror());
1343 _state->clear_class_versions_map();
1344 }
1345 };
1346
1347
1348 jvmtiError VM_RedefineClasses::load_new_class_versions() {
1349
1350 // For consistency allocate memory using os::malloc wrapper.
1351 _scratch_classes = (InstanceKlass**)
1352 os::malloc(sizeof(InstanceKlass*) * _class_count, mtClass);
1353 if (_scratch_classes == NULL) {
1354 return JVMTI_ERROR_OUT_OF_MEMORY;
1355 }
1356 // Zero initialize the _scratch_classes array.
1357 for (int i = 0; i < _class_count; i++) {
1358 _scratch_classes[i] = NULL;
1359 }
1360
1361 JavaThread* current = JavaThread::current();
1362 ResourceMark rm(current);
1363
1364 JvmtiThreadState *state = JvmtiThreadState::state_for(current);
1365 // state can only be NULL if the current thread is exiting which
1366 // should not happen since we're trying to do a RedefineClasses
1367 guarantee(state != NULL, "exiting thread calling load_new_class_versions");
1368 for (int i = 0; i < _class_count; i++) {
1369 // Create HandleMark so that any handles created while loading new class
1370 // versions are deleted. Constant pools are deallocated while merging
1371 // constant pools
1372 HandleMark hm(current);
1373 InstanceKlass* the_class = get_ik(_class_defs[i].klass);
1374
1375 log_debug(redefine, class, load)
1376 ("loading name=%s kind=%d (avail_mem=" UINT64_FORMAT "K)",
1377 the_class->external_name(), _class_load_kind, os::available_memory() >> 10);
1378
1379 ClassFileStream st((u1*)_class_defs[i].class_bytes,
1380 _class_defs[i].class_byte_count,
1381 "__VM_RedefineClasses__",
1382 ClassFileStream::verify);
1383
1384 // Set redefined class handle in JvmtiThreadState class.
1385 // This redefined class is sent to agent event handler for class file
1386 // load hook event.
1387 state->set_class_being_redefined(the_class, _class_load_kind);
1388
1389 JavaThread* THREAD = current; // For exception macros.
1390 ExceptionMark em(THREAD);
1391 Handle protection_domain(THREAD, the_class->protection_domain());
1392 ClassLoadInfo cl_info(protection_domain);
1393 // Parse and create a class from the bytes, but this class isn't added
1394 // to the dictionary, so do not call resolve_from_stream.
1395 InstanceKlass* scratch_class = KlassFactory::create_from_stream(&st,
1396 the_class->name(),
1397 the_class->class_loader_data(),
1398 cl_info,
1399 THREAD);
1400
1401 // Clear class_being_redefined just to be sure.
1402 state->clear_class_being_redefined();
1403
1404 // TODO: if this is retransform, and nothing changed we can skip it
1405
1406 // Need to clean up allocated InstanceKlass if there's an error so assign
1407 // the result here. Caller deallocates all the scratch classes in case of
1408 // an error.
1409 _scratch_classes[i] = scratch_class;
1410
1411 if (HAS_PENDING_EXCEPTION) {
1412 Symbol* ex_name = PENDING_EXCEPTION->klass()->name();
1413 log_info(redefine, class, load, exceptions)("create_from_stream exception: '%s'", ex_name->as_C_string());
1414 CLEAR_PENDING_EXCEPTION;
1415
1416 if (ex_name == vmSymbols::java_lang_UnsupportedClassVersionError()) {
1417 return JVMTI_ERROR_UNSUPPORTED_VERSION;
1418 } else if (ex_name == vmSymbols::java_lang_ClassFormatError()) {
1419 return JVMTI_ERROR_INVALID_CLASS_FORMAT;
1420 } else if (ex_name == vmSymbols::java_lang_ClassCircularityError()) {
1421 return JVMTI_ERROR_CIRCULAR_CLASS_DEFINITION;
1422 } else if (ex_name == vmSymbols::java_lang_NoClassDefFoundError()) {
1423 // The message will be "XXX (wrong name: YYY)"
1424 return JVMTI_ERROR_NAMES_DONT_MATCH;
1425 } else if (ex_name == vmSymbols::java_lang_OutOfMemoryError()) {
1426 return JVMTI_ERROR_OUT_OF_MEMORY;
1427 } else { // Just in case more exceptions can be thrown..
1428 return JVMTI_ERROR_FAILS_VERIFICATION;
1429 }
1430 }
1431
1432 // Ensure class is linked before redefine
1433 if (!the_class->is_linked()) {
1434 the_class->link_class(THREAD);
1435 if (HAS_PENDING_EXCEPTION) {
1436 Symbol* ex_name = PENDING_EXCEPTION->klass()->name();
1437 oop message = java_lang_Throwable::message(PENDING_EXCEPTION);
1438 if (message != NULL) {
1439 char* ex_msg = java_lang_String::as_utf8_string(message);
1440 log_info(redefine, class, load, exceptions)("link_class exception: '%s %s'",
1441 ex_name->as_C_string(), ex_msg);
1442 } else {
1443 log_info(redefine, class, load, exceptions)("link_class exception: '%s'",
1444 ex_name->as_C_string());
1445 }
1446 CLEAR_PENDING_EXCEPTION;
1447 if (ex_name == vmSymbols::java_lang_OutOfMemoryError()) {
1448 return JVMTI_ERROR_OUT_OF_MEMORY;
1449 } else if (ex_name == vmSymbols::java_lang_NoClassDefFoundError()) {
1450 return JVMTI_ERROR_INVALID_CLASS;
1451 } else {
1452 return JVMTI_ERROR_INTERNAL;
1453 }
1454 }
1455 }
1456
1457 // Do the validity checks in compare_and_normalize_class_versions()
1458 // before verifying the byte codes. By doing these checks first, we
1459 // limit the number of functions that require redirection from
1460 // the_class to scratch_class. In particular, we don't have to
1461 // modify JNI GetSuperclass() and thus won't change its performance.
1462 jvmtiError res = compare_and_normalize_class_versions(the_class,
1463 scratch_class);
1464 if (res != JVMTI_ERROR_NONE) {
1465 return res;
1466 }
1467
1468 // verify what the caller passed us
1469 {
1470 // The bug 6214132 caused the verification to fail.
1471 // Information about the_class and scratch_class is temporarily
1472 // recorded into jvmtiThreadState. This data is used to redirect
1473 // the_class to scratch_class in the JVM_* functions called by the
1474 // verifier. Please, refer to jvmtiThreadState.hpp for the detailed
1475 // description.
1476 RedefineVerifyMark rvm(the_class, scratch_class, state);
1477 Verifier::verify(scratch_class, true, THREAD);
1478 }
1479
1480 if (HAS_PENDING_EXCEPTION) {
1481 Symbol* ex_name = PENDING_EXCEPTION->klass()->name();
1482 log_info(redefine, class, load, exceptions)("verify_byte_codes exception: '%s'", ex_name->as_C_string());
1483 CLEAR_PENDING_EXCEPTION;
1484 if (ex_name == vmSymbols::java_lang_OutOfMemoryError()) {
1485 return JVMTI_ERROR_OUT_OF_MEMORY;
1486 } else {
1487 // tell the caller the bytecodes are bad
1488 return JVMTI_ERROR_FAILS_VERIFICATION;
1489 }
1490 }
1491
1492 res = merge_cp_and_rewrite(the_class, scratch_class, THREAD);
1493 if (HAS_PENDING_EXCEPTION) {
1494 Symbol* ex_name = PENDING_EXCEPTION->klass()->name();
1495 log_info(redefine, class, load, exceptions)("merge_cp_and_rewrite exception: '%s'", ex_name->as_C_string());
1496 CLEAR_PENDING_EXCEPTION;
1497 if (ex_name == vmSymbols::java_lang_OutOfMemoryError()) {
1498 return JVMTI_ERROR_OUT_OF_MEMORY;
1499 } else {
1500 return JVMTI_ERROR_INTERNAL;
1501 }
1502 }
1503
1504 #ifdef ASSERT
1505 {
1506 // verify what we have done during constant pool merging
1507 {
1508 RedefineVerifyMark rvm(the_class, scratch_class, state);
1509 Verifier::verify(scratch_class, true, THREAD);
1510 }
1511
1512 if (HAS_PENDING_EXCEPTION) {
1513 Symbol* ex_name = PENDING_EXCEPTION->klass()->name();
1514 log_info(redefine, class, load, exceptions)
1515 ("verify_byte_codes post merge-CP exception: '%s'", ex_name->as_C_string());
1516 CLEAR_PENDING_EXCEPTION;
1517 if (ex_name == vmSymbols::java_lang_OutOfMemoryError()) {
1518 return JVMTI_ERROR_OUT_OF_MEMORY;
1519 } else {
1520 // tell the caller that constant pool merging screwed up
1521 return JVMTI_ERROR_INTERNAL;
1522 }
1523 }
1524 }
1525 #endif // ASSERT
1526
1527 Rewriter::rewrite(scratch_class, THREAD);
1528 if (!HAS_PENDING_EXCEPTION) {
1529 scratch_class->link_methods(THREAD);
1530 }
1531 if (HAS_PENDING_EXCEPTION) {
1532 Symbol* ex_name = PENDING_EXCEPTION->klass()->name();
1533 log_info(redefine, class, load, exceptions)
1534 ("Rewriter::rewrite or link_methods exception: '%s'", ex_name->as_C_string());
1535 CLEAR_PENDING_EXCEPTION;
1536 if (ex_name == vmSymbols::java_lang_OutOfMemoryError()) {
1537 return JVMTI_ERROR_OUT_OF_MEMORY;
1538 } else {
1539 return JVMTI_ERROR_INTERNAL;
1540 }
1541 }
1542
1543 log_debug(redefine, class, load)
1544 ("loaded name=%s (avail_mem=" UINT64_FORMAT "K)", the_class->external_name(), os::available_memory() >> 10);
1545 }
1546
1547 return JVMTI_ERROR_NONE;
1548 }
1549
1550
1551 // Map old_index to new_index as needed. scratch_cp is only needed
1552 // for log calls.
1553 void VM_RedefineClasses::map_index(const constantPoolHandle& scratch_cp,
1554 int old_index, int new_index) {
1555 if (find_new_index(old_index) != 0) {
1556 // old_index is already mapped
1557 return;
1558 }
1559
1560 if (old_index == new_index) {
1561 // no mapping is needed
1562 return;
1563 }
1564
1565 _index_map_p->at_put(old_index, new_index);
1566 _index_map_count++;
1567
1568 log_trace(redefine, class, constantpool)
1569 ("mapped tag %d at index %d to %d", scratch_cp->tag_at(old_index).value(), old_index, new_index);
1570 } // end map_index()
1571
1572
1573 // Map old_index to new_index as needed.
1574 void VM_RedefineClasses::map_operand_index(int old_index, int new_index) {
1575 if (find_new_operand_index(old_index) != -1) {
1576 // old_index is already mapped
1577 return;
1578 }
1579
1580 if (old_index == new_index) {
1581 // no mapping is needed
1582 return;
1583 }
1584
1585 _operands_index_map_p->at_put(old_index, new_index);
1586 _operands_index_map_count++;
1587
1588 log_trace(redefine, class, constantpool)("mapped bootstrap specifier at index %d to %d", old_index, new_index);
1589 } // end map_index()
1590
1591
1592 // Merge old_cp and scratch_cp and return the results of the merge via
1593 // merge_cp_p. The number of entries in *merge_cp_p is returned via
1594 // merge_cp_length_p. The entries in old_cp occupy the same locations
1595 // in *merge_cp_p. Also creates a map of indices from entries in
1596 // scratch_cp to the corresponding entry in *merge_cp_p. Index map
1597 // entries are only created for entries in scratch_cp that occupy a
1598 // different location in *merged_cp_p.
1599 bool VM_RedefineClasses::merge_constant_pools(const constantPoolHandle& old_cp,
1600 const constantPoolHandle& scratch_cp, constantPoolHandle *merge_cp_p,
1601 int *merge_cp_length_p, TRAPS) {
1602
1603 if (merge_cp_p == NULL) {
1604 assert(false, "caller must provide scratch constantPool");
1605 return false; // robustness
1606 }
1607 if (merge_cp_length_p == NULL) {
1608 assert(false, "caller must provide scratch CP length");
1609 return false; // robustness
1610 }
1611 // Worst case we need old_cp->length() + scratch_cp()->length(),
1612 // but the caller might be smart so make sure we have at least
1613 // the minimum.
1614 if ((*merge_cp_p)->length() < old_cp->length()) {
1615 assert(false, "merge area too small");
1616 return false; // robustness
1617 }
1618
1619 log_info(redefine, class, constantpool)("old_cp_len=%d, scratch_cp_len=%d", old_cp->length(), scratch_cp->length());
1620
1621 {
1622 // Pass 0:
1623 // The old_cp is copied to *merge_cp_p; this means that any code
1624 // using old_cp does not have to change. This work looks like a
1625 // perfect fit for ConstantPool*::copy_cp_to(), but we need to
1626 // handle one special case:
1627 // - revert JVM_CONSTANT_Class to JVM_CONSTANT_UnresolvedClass
1628 // This will make verification happy.
1629
1630 int old_i; // index into old_cp
1631
1632 // index zero (0) is not used in constantPools
1633 for (old_i = 1; old_i < old_cp->length(); old_i++) {
1634 // leave debugging crumb
1635 jbyte old_tag = old_cp->tag_at(old_i).value();
1636 switch (old_tag) {
1637 case JVM_CONSTANT_Class:
1638 case JVM_CONSTANT_UnresolvedClass:
1639 // revert the copy to JVM_CONSTANT_UnresolvedClass
1640 // May be resolving while calling this so do the same for
1641 // JVM_CONSTANT_UnresolvedClass (klass_name_at() deals with transition)
1642 (*merge_cp_p)->temp_unresolved_klass_at_put(old_i,
1643 old_cp->klass_name_index_at(old_i));
1644 break;
1645
1646 case JVM_CONSTANT_Double:
1647 case JVM_CONSTANT_Long:
1648 // just copy the entry to *merge_cp_p, but double and long take
1649 // two constant pool entries
1650 ConstantPool::copy_entry_to(old_cp, old_i, *merge_cp_p, old_i);
1651 old_i++;
1652 break;
1653
1654 default:
1655 // just copy the entry to *merge_cp_p
1656 ConstantPool::copy_entry_to(old_cp, old_i, *merge_cp_p, old_i);
1657 break;
1658 }
1659 } // end for each old_cp entry
1660
1661 ConstantPool::copy_operands(old_cp, *merge_cp_p, CHECK_false);
1662 (*merge_cp_p)->extend_operands(scratch_cp, CHECK_false);
1663
1664 // We don't need to sanity check that *merge_cp_length_p is within
1665 // *merge_cp_p bounds since we have the minimum on-entry check above.
1666 (*merge_cp_length_p) = old_i;
1667 }
1668
1669 // merge_cp_len should be the same as old_cp->length() at this point
1670 // so this trace message is really a "warm-and-breathing" message.
1671 log_debug(redefine, class, constantpool)("after pass 0: merge_cp_len=%d", *merge_cp_length_p);
1672
1673 int scratch_i; // index into scratch_cp
1674 {
1675 // Pass 1a:
1676 // Compare scratch_cp entries to the old_cp entries that we have
1677 // already copied to *merge_cp_p. In this pass, we are eliminating
1678 // exact duplicates (matching entry at same index) so we only
1679 // compare entries in the common indice range.
1680 int increment = 1;
1681 int pass1a_length = MIN2(old_cp->length(), scratch_cp->length());
1682 for (scratch_i = 1; scratch_i < pass1a_length; scratch_i += increment) {
1683 switch (scratch_cp->tag_at(scratch_i).value()) {
1684 case JVM_CONSTANT_Double:
1685 case JVM_CONSTANT_Long:
1686 // double and long take two constant pool entries
1687 increment = 2;
1688 break;
1689
1690 default:
1691 increment = 1;
1692 break;
1693 }
1694
1695 bool match = scratch_cp->compare_entry_to(scratch_i, *merge_cp_p, scratch_i);
1696 if (match) {
1697 // found a match at the same index so nothing more to do
1698 continue;
1699 } else if (is_unresolved_class_mismatch(scratch_cp, scratch_i,
1700 *merge_cp_p, scratch_i)) {
1701 // The mismatch in compare_entry_to() above is because of a
1702 // resolved versus unresolved class entry at the same index
1703 // with the same string value. Since Pass 0 reverted any
1704 // class entries to unresolved class entries in *merge_cp_p,
1705 // we go with the unresolved class entry.
1706 continue;
1707 }
1708
1709 int found_i = scratch_cp->find_matching_entry(scratch_i, *merge_cp_p);
1710 if (found_i != 0) {
1711 guarantee(found_i != scratch_i,
1712 "compare_entry_to() and find_matching_entry() do not agree");
1713
1714 // Found a matching entry somewhere else in *merge_cp_p so
1715 // just need a mapping entry.
1716 map_index(scratch_cp, scratch_i, found_i);
1717 continue;
1718 }
1719
1720 // The find_matching_entry() call above could fail to find a match
1721 // due to a resolved versus unresolved class or string entry situation
1722 // like we solved above with the is_unresolved_*_mismatch() calls.
1723 // However, we would have to call is_unresolved_*_mismatch() over
1724 // all of *merge_cp_p (potentially) and that doesn't seem to be
1725 // worth the time.
1726
1727 // No match found so we have to append this entry and any unique
1728 // referenced entries to *merge_cp_p.
1729 append_entry(scratch_cp, scratch_i, merge_cp_p, merge_cp_length_p);
1730 }
1731 }
1732
1733 log_debug(redefine, class, constantpool)
1734 ("after pass 1a: merge_cp_len=%d, scratch_i=%d, index_map_len=%d",
1735 *merge_cp_length_p, scratch_i, _index_map_count);
1736
1737 if (scratch_i < scratch_cp->length()) {
1738 // Pass 1b:
1739 // old_cp is smaller than scratch_cp so there are entries in
1740 // scratch_cp that we have not yet processed. We take care of
1741 // those now.
1742 int increment = 1;
1743 for (; scratch_i < scratch_cp->length(); scratch_i += increment) {
1744 switch (scratch_cp->tag_at(scratch_i).value()) {
1745 case JVM_CONSTANT_Double:
1746 case JVM_CONSTANT_Long:
1747 // double and long take two constant pool entries
1748 increment = 2;
1749 break;
1750
1751 default:
1752 increment = 1;
1753 break;
1754 }
1755
1756 int found_i =
1757 scratch_cp->find_matching_entry(scratch_i, *merge_cp_p);
1758 if (found_i != 0) {
1759 // Found a matching entry somewhere else in *merge_cp_p so
1760 // just need a mapping entry.
1761 map_index(scratch_cp, scratch_i, found_i);
1762 continue;
1763 }
1764
1765 // No match found so we have to append this entry and any unique
1766 // referenced entries to *merge_cp_p.
1767 append_entry(scratch_cp, scratch_i, merge_cp_p, merge_cp_length_p);
1768 }
1769
1770 log_debug(redefine, class, constantpool)
1771 ("after pass 1b: merge_cp_len=%d, scratch_i=%d, index_map_len=%d",
1772 *merge_cp_length_p, scratch_i, _index_map_count);
1773 }
1774 finalize_operands_merge(*merge_cp_p, CHECK_false);
1775
1776 return true;
1777 } // end merge_constant_pools()
1778
1779
1780 // Scoped object to clean up the constant pool(s) created for merging
1781 class MergeCPCleaner {
1782 ClassLoaderData* _loader_data;
1783 ConstantPool* _cp;
1784 ConstantPool* _scratch_cp;
1785 public:
1786 MergeCPCleaner(ClassLoaderData* loader_data, ConstantPool* merge_cp) :
1787 _loader_data(loader_data), _cp(merge_cp), _scratch_cp(NULL) {}
1788 ~MergeCPCleaner() {
1789 _loader_data->add_to_deallocate_list(_cp);
1790 if (_scratch_cp != NULL) {
1791 _loader_data->add_to_deallocate_list(_scratch_cp);
1792 }
1793 }
1794 void add_scratch_cp(ConstantPool* scratch_cp) { _scratch_cp = scratch_cp; }
1795 };
1796
1797 // Merge constant pools between the_class and scratch_class and
1798 // potentially rewrite bytecodes in scratch_class to use the merged
1799 // constant pool.
1800 jvmtiError VM_RedefineClasses::merge_cp_and_rewrite(
1801 InstanceKlass* the_class, InstanceKlass* scratch_class,
1802 TRAPS) {
1803 // worst case merged constant pool length is old and new combined
1804 int merge_cp_length = the_class->constants()->length()
1805 + scratch_class->constants()->length();
1806
1807 // Constant pools are not easily reused so we allocate a new one
1808 // each time.
1809 // merge_cp is created unsafe for concurrent GC processing. It
1810 // should be marked safe before discarding it. Even though
1811 // garbage, if it crosses a card boundary, it may be scanned
1812 // in order to find the start of the first complete object on the card.
1813 ClassLoaderData* loader_data = the_class->class_loader_data();
1814 ConstantPool* merge_cp_oop =
1815 ConstantPool::allocate(loader_data,
1816 merge_cp_length,
1817 CHECK_(JVMTI_ERROR_OUT_OF_MEMORY));
1818 MergeCPCleaner cp_cleaner(loader_data, merge_cp_oop);
1819
1820 HandleMark hm(THREAD); // make sure handles are cleared before
1821 // MergeCPCleaner clears out merge_cp_oop
1822 constantPoolHandle merge_cp(THREAD, merge_cp_oop);
1823
1824 // Get constants() from the old class because it could have been rewritten
1825 // while we were at a safepoint allocating a new constant pool.
1826 constantPoolHandle old_cp(THREAD, the_class->constants());
1827 constantPoolHandle scratch_cp(THREAD, scratch_class->constants());
1828
1829 // If the length changed, the class was redefined out from under us. Return
1830 // an error.
1831 if (merge_cp_length != the_class->constants()->length()
1832 + scratch_class->constants()->length()) {
1833 return JVMTI_ERROR_INTERNAL;
1834 }
1835
1836 // Update the version number of the constant pools (may keep scratch_cp)
1837 merge_cp->increment_and_save_version(old_cp->version());
1838 scratch_cp->increment_and_save_version(old_cp->version());
1839
1840 ResourceMark rm(THREAD);
1841 _index_map_count = 0;
1842 _index_map_p = new intArray(scratch_cp->length(), scratch_cp->length(), -1);
1843
1844 _operands_cur_length = ConstantPool::operand_array_length(old_cp->operands());
1845 _operands_index_map_count = 0;
1846 int operands_index_map_len = ConstantPool::operand_array_length(scratch_cp->operands());
1847 _operands_index_map_p = new intArray(operands_index_map_len, operands_index_map_len, -1);
1848
1849 // reference to the cp holder is needed for copy_operands()
1850 merge_cp->set_pool_holder(scratch_class);
1851 bool result = merge_constant_pools(old_cp, scratch_cp, &merge_cp,
1852 &merge_cp_length, THREAD);
1853 merge_cp->set_pool_holder(NULL);
1854
1855 if (!result) {
1856 // The merge can fail due to memory allocation failure or due
1857 // to robustness checks.
1858 return JVMTI_ERROR_INTERNAL;
1859 }
1860
1861 // Set dynamic constants attribute from the original CP.
1862 if (old_cp->has_dynamic_constant()) {
1863 scratch_cp->set_has_dynamic_constant();
1864 }
1865
1866 log_info(redefine, class, constantpool)("merge_cp_len=%d, index_map_len=%d", merge_cp_length, _index_map_count);
1867
1868 if (_index_map_count == 0) {
1869 // there is nothing to map between the new and merged constant pools
1870
1871 // Copy attributes from scratch_cp to merge_cp
1872 merge_cp->copy_fields(scratch_cp());
1873
1874 if (old_cp->length() == scratch_cp->length()) {
1875 // The old and new constant pools are the same length and the
1876 // index map is empty. This means that the three constant pools
1877 // are equivalent (but not the same). Unfortunately, the new
1878 // constant pool has not gone through link resolution nor have
1879 // the new class bytecodes gone through constant pool cache
1880 // rewriting so we can't use the old constant pool with the new
1881 // class.
1882
1883 // toss the merged constant pool at return
1884 } else if (old_cp->length() < scratch_cp->length()) {
1885 // The old constant pool has fewer entries than the new constant
1886 // pool and the index map is empty. This means the new constant
1887 // pool is a superset of the old constant pool. However, the old
1888 // class bytecodes have already gone through constant pool cache
1889 // rewriting so we can't use the new constant pool with the old
1890 // class.
1891
1892 // toss the merged constant pool at return
1893 } else {
1894 // The old constant pool has more entries than the new constant
1895 // pool and the index map is empty. This means that both the old
1896 // and merged constant pools are supersets of the new constant
1897 // pool.
1898
1899 // Replace the new constant pool with a shrunken copy of the
1900 // merged constant pool
1901 set_new_constant_pool(loader_data, scratch_class, merge_cp, merge_cp_length,
1902 CHECK_(JVMTI_ERROR_OUT_OF_MEMORY));
1903 // The new constant pool replaces scratch_cp so have cleaner clean it up.
1904 // It can't be cleaned up while there are handles to it.
1905 cp_cleaner.add_scratch_cp(scratch_cp());
1906 }
1907 } else {
1908 if (log_is_enabled(Trace, redefine, class, constantpool)) {
1909 // don't want to loop unless we are tracing
1910 int count = 0;
1911 for (int i = 1; i < _index_map_p->length(); i++) {
1912 int value = _index_map_p->at(i);
1913
1914 if (value != -1) {
1915 log_trace(redefine, class, constantpool)("index_map[%d]: old=%d new=%d", count, i, value);
1916 count++;
1917 }
1918 }
1919 }
1920
1921 // We have entries mapped between the new and merged constant pools
1922 // so we have to rewrite some constant pool references.
1923 if (!rewrite_cp_refs(scratch_class)) {
1924 return JVMTI_ERROR_INTERNAL;
1925 }
1926
1927 // Copy attributes from scratch_cp to merge_cp (should be done after rewrite_cp_refs())
1928 merge_cp->copy_fields(scratch_cp());
1929
1930 // Replace the new constant pool with a shrunken copy of the
1931 // merged constant pool so now the rewritten bytecodes have
1932 // valid references; the previous new constant pool will get
1933 // GCed.
1934 set_new_constant_pool(loader_data, scratch_class, merge_cp, merge_cp_length,
1935 CHECK_(JVMTI_ERROR_OUT_OF_MEMORY));
1936 // The new constant pool replaces scratch_cp so have cleaner clean it up.
1937 // It can't be cleaned up while there are handles to it.
1938 cp_cleaner.add_scratch_cp(scratch_cp());
1939 }
1940
1941 return JVMTI_ERROR_NONE;
1942 } // end merge_cp_and_rewrite()
1943
1944
1945 // Rewrite constant pool references in klass scratch_class.
1946 bool VM_RedefineClasses::rewrite_cp_refs(InstanceKlass* scratch_class) {
1947
1948 // rewrite constant pool references in the nest attributes:
1949 if (!rewrite_cp_refs_in_nest_attributes(scratch_class)) {
1950 // propagate failure back to caller
1951 return false;
1952 }
1953
1954 // rewrite constant pool references in the Record attribute:
1955 if (!rewrite_cp_refs_in_record_attribute(scratch_class)) {
1956 // propagate failure back to caller
1957 return false;
1958 }
1959
1960 // rewrite constant pool references in the PermittedSubclasses attribute:
1961 if (!rewrite_cp_refs_in_permitted_subclasses_attribute(scratch_class)) {
1962 // propagate failure back to caller
1963 return false;
1964 }
1965
1966 // rewrite constant pool references in the methods:
1967 if (!rewrite_cp_refs_in_methods(scratch_class)) {
1968 // propagate failure back to caller
1969 return false;
1970 }
1971
1972 // rewrite constant pool references in the class_annotations:
1973 if (!rewrite_cp_refs_in_class_annotations(scratch_class)) {
1974 // propagate failure back to caller
1975 return false;
1976 }
1977
1978 // rewrite constant pool references in the fields_annotations:
1979 if (!rewrite_cp_refs_in_fields_annotations(scratch_class)) {
1980 // propagate failure back to caller
1981 return false;
1982 }
1983
1984 // rewrite constant pool references in the methods_annotations:
1985 if (!rewrite_cp_refs_in_methods_annotations(scratch_class)) {
1986 // propagate failure back to caller
1987 return false;
1988 }
1989
1990 // rewrite constant pool references in the methods_parameter_annotations:
1991 if (!rewrite_cp_refs_in_methods_parameter_annotations(scratch_class)) {
1992 // propagate failure back to caller
1993 return false;
1994 }
1995
1996 // rewrite constant pool references in the methods_default_annotations:
1997 if (!rewrite_cp_refs_in_methods_default_annotations(scratch_class)) {
1998 // propagate failure back to caller
1999 return false;
2000 }
2001
2002 // rewrite constant pool references in the class_type_annotations:
2003 if (!rewrite_cp_refs_in_class_type_annotations(scratch_class)) {
2004 // propagate failure back to caller
2005 return false;
2006 }
2007
2008 // rewrite constant pool references in the fields_type_annotations:
2009 if (!rewrite_cp_refs_in_fields_type_annotations(scratch_class)) {
2010 // propagate failure back to caller
2011 return false;
2012 }
2013
2014 // rewrite constant pool references in the methods_type_annotations:
2015 if (!rewrite_cp_refs_in_methods_type_annotations(scratch_class)) {
2016 // propagate failure back to caller
2017 return false;
2018 }
2019
2020 // There can be type annotations in the Code part of a method_info attribute.
2021 // These annotations are not accessible, even by reflection.
2022 // Currently they are not even parsed by the ClassFileParser.
2023 // If runtime access is added they will also need to be rewritten.
2024
2025 // rewrite source file name index:
2026 u2 source_file_name_idx = scratch_class->source_file_name_index();
2027 if (source_file_name_idx != 0) {
2028 u2 new_source_file_name_idx = find_new_index(source_file_name_idx);
2029 if (new_source_file_name_idx != 0) {
2030 scratch_class->set_source_file_name_index(new_source_file_name_idx);
2031 }
2032 }
2033
2034 // rewrite class generic signature index:
2035 u2 generic_signature_index = scratch_class->generic_signature_index();
2036 if (generic_signature_index != 0) {
2037 u2 new_generic_signature_index = find_new_index(generic_signature_index);
2038 if (new_generic_signature_index != 0) {
2039 scratch_class->set_generic_signature_index(new_generic_signature_index);
2040 }
2041 }
2042
2043 return true;
2044 } // end rewrite_cp_refs()
2045
2046 // Rewrite constant pool references in the NestHost and NestMembers attributes.
2047 bool VM_RedefineClasses::rewrite_cp_refs_in_nest_attributes(
2048 InstanceKlass* scratch_class) {
2049
2050 u2 cp_index = scratch_class->nest_host_index();
2051 if (cp_index != 0) {
2052 scratch_class->set_nest_host_index(find_new_index(cp_index));
2053 }
2054 Array<u2>* nest_members = scratch_class->nest_members();
2055 for (int i = 0; i < nest_members->length(); i++) {
2056 u2 cp_index = nest_members->at(i);
2057 nest_members->at_put(i, find_new_index(cp_index));
2058 }
2059 return true;
2060 }
2061
2062 // Rewrite constant pool references in the Record attribute.
2063 bool VM_RedefineClasses::rewrite_cp_refs_in_record_attribute(InstanceKlass* scratch_class) {
2064 Array<RecordComponent*>* components = scratch_class->record_components();
2065 if (components != NULL) {
2066 for (int i = 0; i < components->length(); i++) {
2067 RecordComponent* component = components->at(i);
2068 u2 cp_index = component->name_index();
2069 component->set_name_index(find_new_index(cp_index));
2070 cp_index = component->descriptor_index();
2071 component->set_descriptor_index(find_new_index(cp_index));
2072 cp_index = component->generic_signature_index();
2073 if (cp_index != 0) {
2074 component->set_generic_signature_index(find_new_index(cp_index));
2075 }
2076
2077 AnnotationArray* annotations = component->annotations();
2078 if (annotations != NULL && annotations->length() != 0) {
2079 int byte_i = 0; // byte index into annotations
2080 if (!rewrite_cp_refs_in_annotations_typeArray(annotations, byte_i)) {
2081 log_debug(redefine, class, annotation)("bad record_component_annotations at %d", i);
2082 // propagate failure back to caller
2083 return false;
2084 }
2085 }
2086
2087 AnnotationArray* type_annotations = component->type_annotations();
2088 if (type_annotations != NULL && type_annotations->length() != 0) {
2089 int byte_i = 0; // byte index into annotations
2090 if (!rewrite_cp_refs_in_annotations_typeArray(type_annotations, byte_i)) {
2091 log_debug(redefine, class, annotation)("bad record_component_type_annotations at %d", i);
2092 // propagate failure back to caller
2093 return false;
2094 }
2095 }
2096 }
2097 }
2098 return true;
2099 }
2100
2101 // Rewrite constant pool references in the PermittedSubclasses attribute.
2102 bool VM_RedefineClasses::rewrite_cp_refs_in_permitted_subclasses_attribute(
2103 InstanceKlass* scratch_class) {
2104
2105 Array<u2>* permitted_subclasses = scratch_class->permitted_subclasses();
2106 assert(permitted_subclasses != NULL, "unexpected null permitted_subclasses");
2107 for (int i = 0; i < permitted_subclasses->length(); i++) {
2108 u2 cp_index = permitted_subclasses->at(i);
2109 permitted_subclasses->at_put(i, find_new_index(cp_index));
2110 }
2111 return true;
2112 }
2113
2114 // Rewrite constant pool references in the methods.
2115 bool VM_RedefineClasses::rewrite_cp_refs_in_methods(InstanceKlass* scratch_class) {
2116
2117 Array<Method*>* methods = scratch_class->methods();
2118
2119 if (methods == NULL || methods->length() == 0) {
2120 // no methods so nothing to do
2121 return true;
2122 }
2123
2124 JavaThread* THREAD = JavaThread::current(); // For exception macros.
2125 ExceptionMark em(THREAD);
2126
2127 // rewrite constant pool references in the methods:
2128 for (int i = methods->length() - 1; i >= 0; i--) {
2129 methodHandle method(THREAD, methods->at(i));
2130 methodHandle new_method;
2131 rewrite_cp_refs_in_method(method, &new_method, THREAD);
2132 if (!new_method.is_null()) {
2133 // the method has been replaced so save the new method version
2134 // even in the case of an exception. original method is on the
2135 // deallocation list.
2136 methods->at_put(i, new_method());
2137 }
2138 if (HAS_PENDING_EXCEPTION) {
2139 Symbol* ex_name = PENDING_EXCEPTION->klass()->name();
2140 log_info(redefine, class, load, exceptions)("rewrite_cp_refs_in_method exception: '%s'", ex_name->as_C_string());
2141 // Need to clear pending exception here as the super caller sets
2142 // the JVMTI_ERROR_INTERNAL if the returned value is false.
2143 CLEAR_PENDING_EXCEPTION;
2144 return false;
2145 }
2146 }
2147
2148 return true;
2149 }
2150
2151
2152 // Rewrite constant pool references in the specific method. This code
2153 // was adapted from Rewriter::rewrite_method().
2154 void VM_RedefineClasses::rewrite_cp_refs_in_method(methodHandle method,
2155 methodHandle *new_method_p, TRAPS) {
2156
2157 *new_method_p = methodHandle(); // default is no new method
2158
2159 // We cache a pointer to the bytecodes here in code_base. If GC
2160 // moves the Method*, then the bytecodes will also move which
2161 // will likely cause a crash. We create a NoSafepointVerifier
2162 // object to detect whether we pass a possible safepoint in this
2163 // code block.
2164 NoSafepointVerifier nsv;
2165
2166 // Bytecodes and their length
2167 address code_base = method->code_base();
2168 int code_length = method->code_size();
2169
2170 int bc_length;
2171 for (int bci = 0; bci < code_length; bci += bc_length) {
2172 address bcp = code_base + bci;
2173 Bytecodes::Code c = (Bytecodes::Code)(*bcp);
2174
2175 bc_length = Bytecodes::length_for(c);
2176 if (bc_length == 0) {
2177 // More complicated bytecodes report a length of zero so
2178 // we have to try again a slightly different way.
2179 bc_length = Bytecodes::length_at(method(), bcp);
2180 }
2181
2182 assert(bc_length != 0, "impossible bytecode length");
2183
2184 switch (c) {
2185 case Bytecodes::_ldc:
2186 {
2187 int cp_index = *(bcp + 1);
2188 int new_index = find_new_index(cp_index);
2189
2190 if (StressLdcRewrite && new_index == 0) {
2191 // If we are stressing ldc -> ldc_w rewriting, then we
2192 // always need a new_index value.
2193 new_index = cp_index;
2194 }
2195 if (new_index != 0) {
2196 // the original index is mapped so we have more work to do
2197 if (!StressLdcRewrite && new_index <= max_jubyte) {
2198 // The new value can still use ldc instead of ldc_w
2199 // unless we are trying to stress ldc -> ldc_w rewriting
2200 log_trace(redefine, class, constantpool)
2201 ("%s@" INTPTR_FORMAT " old=%d, new=%d", Bytecodes::name(c), p2i(bcp), cp_index, new_index);
2202 *(bcp + 1) = new_index;
2203 } else {
2204 log_trace(redefine, class, constantpool)
2205 ("%s->ldc_w@" INTPTR_FORMAT " old=%d, new=%d", Bytecodes::name(c), p2i(bcp), cp_index, new_index);
2206 // the new value needs ldc_w instead of ldc
2207 u_char inst_buffer[4]; // max instruction size is 4 bytes
2208 bcp = (address)inst_buffer;
2209 // construct new instruction sequence
2210 *bcp = Bytecodes::_ldc_w;
2211 bcp++;
2212 // Rewriter::rewrite_method() does not rewrite ldc -> ldc_w.
2213 // See comment below for difference between put_Java_u2()
2214 // and put_native_u2().
2215 Bytes::put_Java_u2(bcp, new_index);
2216
2217 Relocator rc(method, NULL /* no RelocatorListener needed */);
2218 methodHandle m;
2219 {
2220 PauseNoSafepointVerifier pnsv(&nsv);
2221
2222 // ldc is 2 bytes and ldc_w is 3 bytes
2223 m = rc.insert_space_at(bci, 3, inst_buffer, CHECK);
2224 }
2225
2226 // return the new method so that the caller can update
2227 // the containing class
2228 *new_method_p = method = m;
2229 // switch our bytecode processing loop from the old method
2230 // to the new method
2231 code_base = method->code_base();
2232 code_length = method->code_size();
2233 bcp = code_base + bci;
2234 c = (Bytecodes::Code)(*bcp);
2235 bc_length = Bytecodes::length_for(c);
2236 assert(bc_length != 0, "sanity check");
2237 } // end we need ldc_w instead of ldc
2238 } // end if there is a mapped index
2239 } break;
2240
2241 // these bytecodes have a two-byte constant pool index
2242 case Bytecodes::_anewarray : // fall through
2243 case Bytecodes::_checkcast : // fall through
2244 case Bytecodes::_getfield : // fall through
2245 case Bytecodes::_getstatic : // fall through
2246 case Bytecodes::_instanceof : // fall through
2247 case Bytecodes::_invokedynamic : // fall through
2248 case Bytecodes::_invokeinterface: // fall through
2249 case Bytecodes::_invokespecial : // fall through
2250 case Bytecodes::_invokestatic : // fall through
2251 case Bytecodes::_invokevirtual : // fall through
2252 case Bytecodes::_ldc_w : // fall through
2253 case Bytecodes::_ldc2_w : // fall through
2254 case Bytecodes::_multianewarray : // fall through
2255 case Bytecodes::_new : // fall through
2256 case Bytecodes::_putfield : // fall through
2257 case Bytecodes::_putstatic :
2258 {
2259 address p = bcp + 1;
2260 int cp_index = Bytes::get_Java_u2(p);
2261 int new_index = find_new_index(cp_index);
2262 if (new_index != 0) {
2263 // the original index is mapped so update w/ new value
2264 log_trace(redefine, class, constantpool)
2265 ("%s@" INTPTR_FORMAT " old=%d, new=%d", Bytecodes::name(c),p2i(bcp), cp_index, new_index);
2266 // Rewriter::rewrite_method() uses put_native_u2() in this
2267 // situation because it is reusing the constant pool index
2268 // location for a native index into the ConstantPoolCache.
2269 // Since we are updating the constant pool index prior to
2270 // verification and ConstantPoolCache initialization, we
2271 // need to keep the new index in Java byte order.
2272 Bytes::put_Java_u2(p, new_index);
2273 }
2274 } break;
2275 default:
2276 break;
2277 }
2278 } // end for each bytecode
2279 } // end rewrite_cp_refs_in_method()
2280
2281
2282 // Rewrite constant pool references in the class_annotations field.
2283 bool VM_RedefineClasses::rewrite_cp_refs_in_class_annotations(InstanceKlass* scratch_class) {
2284
2285 AnnotationArray* class_annotations = scratch_class->class_annotations();
2286 if (class_annotations == NULL || class_annotations->length() == 0) {
2287 // no class_annotations so nothing to do
2288 return true;
2289 }
2290
2291 log_debug(redefine, class, annotation)("class_annotations length=%d", class_annotations->length());
2292
2293 int byte_i = 0; // byte index into class_annotations
2294 return rewrite_cp_refs_in_annotations_typeArray(class_annotations, byte_i);
2295 }
2296
2297
2298 // Rewrite constant pool references in an annotations typeArray. This
2299 // "structure" is adapted from the RuntimeVisibleAnnotations_attribute
2300 // that is described in section 4.8.15 of the 2nd-edition of the VM spec:
2301 //
2302 // annotations_typeArray {
2303 // u2 num_annotations;
2304 // annotation annotations[num_annotations];
2305 // }
2306 //
2307 bool VM_RedefineClasses::rewrite_cp_refs_in_annotations_typeArray(
2308 AnnotationArray* annotations_typeArray, int &byte_i_ref) {
2309
2310 if ((byte_i_ref + 2) > annotations_typeArray->length()) {
2311 // not enough room for num_annotations field
2312 log_debug(redefine, class, annotation)("length() is too small for num_annotations field");
2313 return false;
2314 }
2315
2316 u2 num_annotations = Bytes::get_Java_u2((address)
2317 annotations_typeArray->adr_at(byte_i_ref));
2318 byte_i_ref += 2;
2319
2320 log_debug(redefine, class, annotation)("num_annotations=%d", num_annotations);
2321
2322 int calc_num_annotations = 0;
2323 for (; calc_num_annotations < num_annotations; calc_num_annotations++) {
2324 if (!rewrite_cp_refs_in_annotation_struct(annotations_typeArray, byte_i_ref)) {
2325 log_debug(redefine, class, annotation)("bad annotation_struct at %d", calc_num_annotations);
2326 // propagate failure back to caller
2327 return false;
2328 }
2329 }
2330 assert(num_annotations == calc_num_annotations, "sanity check");
2331
2332 return true;
2333 } // end rewrite_cp_refs_in_annotations_typeArray()
2334
2335
2336 // Rewrite constant pool references in the annotation struct portion of
2337 // an annotations_typeArray. This "structure" is from section 4.8.15 of
2338 // the 2nd-edition of the VM spec:
2339 //
2340 // struct annotation {
2341 // u2 type_index;
2342 // u2 num_element_value_pairs;
2343 // {
2344 // u2 element_name_index;
2345 // element_value value;
2346 // } element_value_pairs[num_element_value_pairs];
2347 // }
2348 //
2349 bool VM_RedefineClasses::rewrite_cp_refs_in_annotation_struct(
2350 AnnotationArray* annotations_typeArray, int &byte_i_ref) {
2351 if ((byte_i_ref + 2 + 2) > annotations_typeArray->length()) {
2352 // not enough room for smallest annotation_struct
2353 log_debug(redefine, class, annotation)("length() is too small for annotation_struct");
2354 return false;
2355 }
2356
2357 u2 type_index = rewrite_cp_ref_in_annotation_data(annotations_typeArray,
2358 byte_i_ref, "type_index");
2359
2360 u2 num_element_value_pairs = Bytes::get_Java_u2((address)
2361 annotations_typeArray->adr_at(byte_i_ref));
2362 byte_i_ref += 2;
2363
2364 log_debug(redefine, class, annotation)
2365 ("type_index=%d num_element_value_pairs=%d", type_index, num_element_value_pairs);
2366
2367 int calc_num_element_value_pairs = 0;
2368 for (; calc_num_element_value_pairs < num_element_value_pairs;
2369 calc_num_element_value_pairs++) {
2370 if ((byte_i_ref + 2) > annotations_typeArray->length()) {
2371 // not enough room for another element_name_index, let alone
2372 // the rest of another component
2373 log_debug(redefine, class, annotation)("length() is too small for element_name_index");
2374 return false;
2375 }
2376
2377 u2 element_name_index = rewrite_cp_ref_in_annotation_data(
2378 annotations_typeArray, byte_i_ref,
2379 "element_name_index");
2380
2381 log_debug(redefine, class, annotation)("element_name_index=%d", element_name_index);
2382
2383 if (!rewrite_cp_refs_in_element_value(annotations_typeArray, byte_i_ref)) {
2384 log_debug(redefine, class, annotation)("bad element_value at %d", calc_num_element_value_pairs);
2385 // propagate failure back to caller
2386 return false;
2387 }
2388 } // end for each component
2389 assert(num_element_value_pairs == calc_num_element_value_pairs,
2390 "sanity check");
2391
2392 return true;
2393 } // end rewrite_cp_refs_in_annotation_struct()
2394
2395
2396 // Rewrite a constant pool reference at the current position in
2397 // annotations_typeArray if needed. Returns the original constant
2398 // pool reference if a rewrite was not needed or the new constant
2399 // pool reference if a rewrite was needed.
2400 u2 VM_RedefineClasses::rewrite_cp_ref_in_annotation_data(
2401 AnnotationArray* annotations_typeArray, int &byte_i_ref,
2402 const char * trace_mesg) {
2403
2404 address cp_index_addr = (address)
2405 annotations_typeArray->adr_at(byte_i_ref);
2406 u2 old_cp_index = Bytes::get_Java_u2(cp_index_addr);
2407 u2 new_cp_index = find_new_index(old_cp_index);
2408 if (new_cp_index != 0) {
2409 log_debug(redefine, class, annotation)("mapped old %s=%d", trace_mesg, old_cp_index);
2410 Bytes::put_Java_u2(cp_index_addr, new_cp_index);
2411 old_cp_index = new_cp_index;
2412 }
2413 byte_i_ref += 2;
2414 return old_cp_index;
2415 }
2416
2417
2418 // Rewrite constant pool references in the element_value portion of an
2419 // annotations_typeArray. This "structure" is from section 4.8.15.1 of
2420 // the 2nd-edition of the VM spec:
2421 //
2422 // struct element_value {
2423 // u1 tag;
2424 // union {
2425 // u2 const_value_index;
2426 // {
2427 // u2 type_name_index;
2428 // u2 const_name_index;
2429 // } enum_const_value;
2430 // u2 class_info_index;
2431 // annotation annotation_value;
2432 // struct {
2433 // u2 num_values;
2434 // element_value values[num_values];
2435 // } array_value;
2436 // } value;
2437 // }
2438 //
2439 bool VM_RedefineClasses::rewrite_cp_refs_in_element_value(
2440 AnnotationArray* annotations_typeArray, int &byte_i_ref) {
2441
2442 if ((byte_i_ref + 1) > annotations_typeArray->length()) {
2443 // not enough room for a tag let alone the rest of an element_value
2444 log_debug(redefine, class, annotation)("length() is too small for a tag");
2445 return false;
2446 }
2447
2448 u1 tag = annotations_typeArray->at(byte_i_ref);
2449 byte_i_ref++;
2450 log_debug(redefine, class, annotation)("tag='%c'", tag);
2451
2452 switch (tag) {
2453 // These BaseType tag values are from Table 4.2 in VM spec:
2454 case JVM_SIGNATURE_BYTE:
2455 case JVM_SIGNATURE_CHAR:
2456 case JVM_SIGNATURE_DOUBLE:
2457 case JVM_SIGNATURE_FLOAT:
2458 case JVM_SIGNATURE_INT:
2459 case JVM_SIGNATURE_LONG:
2460 case JVM_SIGNATURE_SHORT:
2461 case JVM_SIGNATURE_BOOLEAN:
2462
2463 // The remaining tag values are from Table 4.8 in the 2nd-edition of
2464 // the VM spec:
2465 case 's':
2466 {
2467 // For the above tag values (including the BaseType values),
2468 // value.const_value_index is right union field.
2469
2470 if ((byte_i_ref + 2) > annotations_typeArray->length()) {
2471 // not enough room for a const_value_index
2472 log_debug(redefine, class, annotation)("length() is too small for a const_value_index");
2473 return false;
2474 }
2475
2476 u2 const_value_index = rewrite_cp_ref_in_annotation_data(
2477 annotations_typeArray, byte_i_ref,
2478 "const_value_index");
2479
2480 log_debug(redefine, class, annotation)("const_value_index=%d", const_value_index);
2481 } break;
2482
2483 case 'e':
2484 {
2485 // for the above tag value, value.enum_const_value is right union field
2486
2487 if ((byte_i_ref + 4) > annotations_typeArray->length()) {
2488 // not enough room for a enum_const_value
2489 log_debug(redefine, class, annotation)("length() is too small for a enum_const_value");
2490 return false;
2491 }
2492
2493 u2 type_name_index = rewrite_cp_ref_in_annotation_data(
2494 annotations_typeArray, byte_i_ref,
2495 "type_name_index");
2496
2497 u2 const_name_index = rewrite_cp_ref_in_annotation_data(
2498 annotations_typeArray, byte_i_ref,
2499 "const_name_index");
2500
2501 log_debug(redefine, class, annotation)
2502 ("type_name_index=%d const_name_index=%d", type_name_index, const_name_index);
2503 } break;
2504
2505 case 'c':
2506 {
2507 // for the above tag value, value.class_info_index is right union field
2508
2509 if ((byte_i_ref + 2) > annotations_typeArray->length()) {
2510 // not enough room for a class_info_index
2511 log_debug(redefine, class, annotation)("length() is too small for a class_info_index");
2512 return false;
2513 }
2514
2515 u2 class_info_index = rewrite_cp_ref_in_annotation_data(
2516 annotations_typeArray, byte_i_ref,
2517 "class_info_index");
2518
2519 log_debug(redefine, class, annotation)("class_info_index=%d", class_info_index);
2520 } break;
2521
2522 case '@':
2523 // For the above tag value, value.attr_value is the right union
2524 // field. This is a nested annotation.
2525 if (!rewrite_cp_refs_in_annotation_struct(annotations_typeArray, byte_i_ref)) {
2526 // propagate failure back to caller
2527 return false;
2528 }
2529 break;
2530
2531 case JVM_SIGNATURE_ARRAY:
2532 {
2533 if ((byte_i_ref + 2) > annotations_typeArray->length()) {
2534 // not enough room for a num_values field
2535 log_debug(redefine, class, annotation)("length() is too small for a num_values field");
2536 return false;
2537 }
2538
2539 // For the above tag value, value.array_value is the right union
2540 // field. This is an array of nested element_value.
2541 u2 num_values = Bytes::get_Java_u2((address)
2542 annotations_typeArray->adr_at(byte_i_ref));
2543 byte_i_ref += 2;
2544 log_debug(redefine, class, annotation)("num_values=%d", num_values);
2545
2546 int calc_num_values = 0;
2547 for (; calc_num_values < num_values; calc_num_values++) {
2548 if (!rewrite_cp_refs_in_element_value(annotations_typeArray, byte_i_ref)) {
2549 log_debug(redefine, class, annotation)("bad nested element_value at %d", calc_num_values);
2550 // propagate failure back to caller
2551 return false;
2552 }
2553 }
2554 assert(num_values == calc_num_values, "sanity check");
2555 } break;
2556
2557 default:
2558 log_debug(redefine, class, annotation)("bad tag=0x%x", tag);
2559 return false;
2560 } // end decode tag field
2561
2562 return true;
2563 } // end rewrite_cp_refs_in_element_value()
2564
2565
2566 // Rewrite constant pool references in a fields_annotations field.
2567 bool VM_RedefineClasses::rewrite_cp_refs_in_fields_annotations(
2568 InstanceKlass* scratch_class) {
2569
2570 Array<AnnotationArray*>* fields_annotations = scratch_class->fields_annotations();
2571
2572 if (fields_annotations == NULL || fields_annotations->length() == 0) {
2573 // no fields_annotations so nothing to do
2574 return true;
2575 }
2576
2577 log_debug(redefine, class, annotation)("fields_annotations length=%d", fields_annotations->length());
2578
2579 for (int i = 0; i < fields_annotations->length(); i++) {
2580 AnnotationArray* field_annotations = fields_annotations->at(i);
2581 if (field_annotations == NULL || field_annotations->length() == 0) {
2582 // this field does not have any annotations so skip it
2583 continue;
2584 }
2585
2586 int byte_i = 0; // byte index into field_annotations
2587 if (!rewrite_cp_refs_in_annotations_typeArray(field_annotations, byte_i)) {
2588 log_debug(redefine, class, annotation)("bad field_annotations at %d", i);
2589 // propagate failure back to caller
2590 return false;
2591 }
2592 }
2593
2594 return true;
2595 } // end rewrite_cp_refs_in_fields_annotations()
2596
2597
2598 // Rewrite constant pool references in a methods_annotations field.
2599 bool VM_RedefineClasses::rewrite_cp_refs_in_methods_annotations(
2600 InstanceKlass* scratch_class) {
2601
2602 for (int i = 0; i < scratch_class->methods()->length(); i++) {
2603 Method* m = scratch_class->methods()->at(i);
2604 AnnotationArray* method_annotations = m->constMethod()->method_annotations();
2605
2606 if (method_annotations == NULL || method_annotations->length() == 0) {
2607 // this method does not have any annotations so skip it
2608 continue;
2609 }
2610
2611 int byte_i = 0; // byte index into method_annotations
2612 if (!rewrite_cp_refs_in_annotations_typeArray(method_annotations, byte_i)) {
2613 log_debug(redefine, class, annotation)("bad method_annotations at %d", i);
2614 // propagate failure back to caller
2615 return false;
2616 }
2617 }
2618
2619 return true;
2620 } // end rewrite_cp_refs_in_methods_annotations()
2621
2622
2623 // Rewrite constant pool references in a methods_parameter_annotations
2624 // field. This "structure" is adapted from the
2625 // RuntimeVisibleParameterAnnotations_attribute described in section
2626 // 4.8.17 of the 2nd-edition of the VM spec:
2627 //
2628 // methods_parameter_annotations_typeArray {
2629 // u1 num_parameters;
2630 // {
2631 // u2 num_annotations;
2632 // annotation annotations[num_annotations];
2633 // } parameter_annotations[num_parameters];
2634 // }
2635 //
2636 bool VM_RedefineClasses::rewrite_cp_refs_in_methods_parameter_annotations(
2637 InstanceKlass* scratch_class) {
2638
2639 for (int i = 0; i < scratch_class->methods()->length(); i++) {
2640 Method* m = scratch_class->methods()->at(i);
2641 AnnotationArray* method_parameter_annotations = m->constMethod()->parameter_annotations();
2642 if (method_parameter_annotations == NULL
2643 || method_parameter_annotations->length() == 0) {
2644 // this method does not have any parameter annotations so skip it
2645 continue;
2646 }
2647
2648 if (method_parameter_annotations->length() < 1) {
2649 // not enough room for a num_parameters field
2650 log_debug(redefine, class, annotation)("length() is too small for a num_parameters field at %d", i);
2651 return false;
2652 }
2653
2654 int byte_i = 0; // byte index into method_parameter_annotations
2655
2656 u1 num_parameters = method_parameter_annotations->at(byte_i);
2657 byte_i++;
2658
2659 log_debug(redefine, class, annotation)("num_parameters=%d", num_parameters);
2660
2661 int calc_num_parameters = 0;
2662 for (; calc_num_parameters < num_parameters; calc_num_parameters++) {
2663 if (!rewrite_cp_refs_in_annotations_typeArray(method_parameter_annotations, byte_i)) {
2664 log_debug(redefine, class, annotation)("bad method_parameter_annotations at %d", calc_num_parameters);
2665 // propagate failure back to caller
2666 return false;
2667 }
2668 }
2669 assert(num_parameters == calc_num_parameters, "sanity check");
2670 }
2671
2672 return true;
2673 } // end rewrite_cp_refs_in_methods_parameter_annotations()
2674
2675
2676 // Rewrite constant pool references in a methods_default_annotations
2677 // field. This "structure" is adapted from the AnnotationDefault_attribute
2678 // that is described in section 4.8.19 of the 2nd-edition of the VM spec:
2679 //
2680 // methods_default_annotations_typeArray {
2681 // element_value default_value;
2682 // }
2683 //
2684 bool VM_RedefineClasses::rewrite_cp_refs_in_methods_default_annotations(
2685 InstanceKlass* scratch_class) {
2686
2687 for (int i = 0; i < scratch_class->methods()->length(); i++) {
2688 Method* m = scratch_class->methods()->at(i);
2689 AnnotationArray* method_default_annotations = m->constMethod()->default_annotations();
2690 if (method_default_annotations == NULL
2691 || method_default_annotations->length() == 0) {
2692 // this method does not have any default annotations so skip it
2693 continue;
2694 }
2695
2696 int byte_i = 0; // byte index into method_default_annotations
2697
2698 if (!rewrite_cp_refs_in_element_value(
2699 method_default_annotations, byte_i)) {
2700 log_debug(redefine, class, annotation)("bad default element_value at %d", i);
2701 // propagate failure back to caller
2702 return false;
2703 }
2704 }
2705
2706 return true;
2707 } // end rewrite_cp_refs_in_methods_default_annotations()
2708
2709
2710 // Rewrite constant pool references in a class_type_annotations field.
2711 bool VM_RedefineClasses::rewrite_cp_refs_in_class_type_annotations(
2712 InstanceKlass* scratch_class) {
2713
2714 AnnotationArray* class_type_annotations = scratch_class->class_type_annotations();
2715 if (class_type_annotations == NULL || class_type_annotations->length() == 0) {
2716 // no class_type_annotations so nothing to do
2717 return true;
2718 }
2719
2720 log_debug(redefine, class, annotation)("class_type_annotations length=%d", class_type_annotations->length());
2721
2722 int byte_i = 0; // byte index into class_type_annotations
2723 return rewrite_cp_refs_in_type_annotations_typeArray(class_type_annotations,
2724 byte_i, "ClassFile");
2725 } // end rewrite_cp_refs_in_class_type_annotations()
2726
2727
2728 // Rewrite constant pool references in a fields_type_annotations field.
2729 bool VM_RedefineClasses::rewrite_cp_refs_in_fields_type_annotations(InstanceKlass* scratch_class) {
2730
2731 Array<AnnotationArray*>* fields_type_annotations = scratch_class->fields_type_annotations();
2732 if (fields_type_annotations == NULL || fields_type_annotations->length() == 0) {
2733 // no fields_type_annotations so nothing to do
2734 return true;
2735 }
2736
2737 log_debug(redefine, class, annotation)("fields_type_annotations length=%d", fields_type_annotations->length());
2738
2739 for (int i = 0; i < fields_type_annotations->length(); i++) {
2740 AnnotationArray* field_type_annotations = fields_type_annotations->at(i);
2741 if (field_type_annotations == NULL || field_type_annotations->length() == 0) {
2742 // this field does not have any annotations so skip it
2743 continue;
2744 }
2745
2746 int byte_i = 0; // byte index into field_type_annotations
2747 if (!rewrite_cp_refs_in_type_annotations_typeArray(field_type_annotations,
2748 byte_i, "field_info")) {
2749 log_debug(redefine, class, annotation)("bad field_type_annotations at %d", i);
2750 // propagate failure back to caller
2751 return false;
2752 }
2753 }
2754
2755 return true;
2756 } // end rewrite_cp_refs_in_fields_type_annotations()
2757
2758
2759 // Rewrite constant pool references in a methods_type_annotations field.
2760 bool VM_RedefineClasses::rewrite_cp_refs_in_methods_type_annotations(
2761 InstanceKlass* scratch_class) {
2762
2763 for (int i = 0; i < scratch_class->methods()->length(); i++) {
2764 Method* m = scratch_class->methods()->at(i);
2765 AnnotationArray* method_type_annotations = m->constMethod()->type_annotations();
2766
2767 if (method_type_annotations == NULL || method_type_annotations->length() == 0) {
2768 // this method does not have any annotations so skip it
2769 continue;
2770 }
2771
2772 log_debug(redefine, class, annotation)("methods type_annotations length=%d", method_type_annotations->length());
2773
2774 int byte_i = 0; // byte index into method_type_annotations
2775 if (!rewrite_cp_refs_in_type_annotations_typeArray(method_type_annotations,
2776 byte_i, "method_info")) {
2777 log_debug(redefine, class, annotation)("bad method_type_annotations at %d", i);
2778 // propagate failure back to caller
2779 return false;
2780 }
2781 }
2782
2783 return true;
2784 } // end rewrite_cp_refs_in_methods_type_annotations()
2785
2786
2787 // Rewrite constant pool references in a type_annotations
2788 // field. This "structure" is adapted from the
2789 // RuntimeVisibleTypeAnnotations_attribute described in
2790 // section 4.7.20 of the Java SE 8 Edition of the VM spec:
2791 //
2792 // type_annotations_typeArray {
2793 // u2 num_annotations;
2794 // type_annotation annotations[num_annotations];
2795 // }
2796 //
2797 bool VM_RedefineClasses::rewrite_cp_refs_in_type_annotations_typeArray(
2798 AnnotationArray* type_annotations_typeArray, int &byte_i_ref,
2799 const char * location_mesg) {
2800
2801 if ((byte_i_ref + 2) > type_annotations_typeArray->length()) {
2802 // not enough room for num_annotations field
2803 log_debug(redefine, class, annotation)("length() is too small for num_annotations field");
2804 return false;
2805 }
2806
2807 u2 num_annotations = Bytes::get_Java_u2((address)
2808 type_annotations_typeArray->adr_at(byte_i_ref));
2809 byte_i_ref += 2;
2810
2811 log_debug(redefine, class, annotation)("num_type_annotations=%d", num_annotations);
2812
2813 int calc_num_annotations = 0;
2814 for (; calc_num_annotations < num_annotations; calc_num_annotations++) {
2815 if (!rewrite_cp_refs_in_type_annotation_struct(type_annotations_typeArray,
2816 byte_i_ref, location_mesg)) {
2817 log_debug(redefine, class, annotation)("bad type_annotation_struct at %d", calc_num_annotations);
2818 // propagate failure back to caller
2819 return false;
2820 }
2821 }
2822 assert(num_annotations == calc_num_annotations, "sanity check");
2823
2824 if (byte_i_ref != type_annotations_typeArray->length()) {
2825 log_debug(redefine, class, annotation)
2826 ("read wrong amount of bytes at end of processing type_annotations_typeArray (%d of %d bytes were read)",
2827 byte_i_ref, type_annotations_typeArray->length());
2828 return false;
2829 }
2830
2831 return true;
2832 } // end rewrite_cp_refs_in_type_annotations_typeArray()
2833
2834
2835 // Rewrite constant pool references in a type_annotation
2836 // field. This "structure" is adapted from the
2837 // RuntimeVisibleTypeAnnotations_attribute described in
2838 // section 4.7.20 of the Java SE 8 Edition of the VM spec:
2839 //
2840 // type_annotation {
2841 // u1 target_type;
2842 // union {
2843 // type_parameter_target;
2844 // supertype_target;
2845 // type_parameter_bound_target;
2846 // empty_target;
2847 // method_formal_parameter_target;
2848 // throws_target;
2849 // localvar_target;
2850 // catch_target;
2851 // offset_target;
2852 // type_argument_target;
2853 // } target_info;
2854 // type_path target_path;
2855 // annotation anno;
2856 // }
2857 //
2858 bool VM_RedefineClasses::rewrite_cp_refs_in_type_annotation_struct(
2859 AnnotationArray* type_annotations_typeArray, int &byte_i_ref,
2860 const char * location_mesg) {
2861
2862 if (!skip_type_annotation_target(type_annotations_typeArray,
2863 byte_i_ref, location_mesg)) {
2864 return false;
2865 }
2866
2867 if (!skip_type_annotation_type_path(type_annotations_typeArray, byte_i_ref)) {
2868 return false;
2869 }
2870
2871 if (!rewrite_cp_refs_in_annotation_struct(type_annotations_typeArray, byte_i_ref)) {
2872 return false;
2873 }
2874
2875 return true;
2876 } // end rewrite_cp_refs_in_type_annotation_struct()
2877
2878
2879 // Read, verify and skip over the target_type and target_info part
2880 // so that rewriting can continue in the later parts of the struct.
2881 //
2882 // u1 target_type;
2883 // union {
2884 // type_parameter_target;
2885 // supertype_target;
2886 // type_parameter_bound_target;
2887 // empty_target;
2888 // method_formal_parameter_target;
2889 // throws_target;
2890 // localvar_target;
2891 // catch_target;
2892 // offset_target;
2893 // type_argument_target;
2894 // } target_info;
2895 //
2896 bool VM_RedefineClasses::skip_type_annotation_target(
2897 AnnotationArray* type_annotations_typeArray, int &byte_i_ref,
2898 const char * location_mesg) {
2899
2900 if ((byte_i_ref + 1) > type_annotations_typeArray->length()) {
2901 // not enough room for a target_type let alone the rest of a type_annotation
2902 log_debug(redefine, class, annotation)("length() is too small for a target_type");
2903 return false;
2904 }
2905
2906 u1 target_type = type_annotations_typeArray->at(byte_i_ref);
2907 byte_i_ref += 1;
2908 log_debug(redefine, class, annotation)("target_type=0x%.2x", target_type);
2909 log_debug(redefine, class, annotation)("location=%s", location_mesg);
2910
2911 // Skip over target_info
2912 switch (target_type) {
2913 case 0x00:
2914 // kind: type parameter declaration of generic class or interface
2915 // location: ClassFile
2916 case 0x01:
2917 // kind: type parameter declaration of generic method or constructor
2918 // location: method_info
2919
2920 {
2921 // struct:
2922 // type_parameter_target {
2923 // u1 type_parameter_index;
2924 // }
2925 //
2926 if ((byte_i_ref + 1) > type_annotations_typeArray->length()) {
2927 log_debug(redefine, class, annotation)("length() is too small for a type_parameter_target");
2928 return false;
2929 }
2930
2931 u1 type_parameter_index = type_annotations_typeArray->at(byte_i_ref);
2932 byte_i_ref += 1;
2933
2934 log_debug(redefine, class, annotation)("type_parameter_target: type_parameter_index=%d", type_parameter_index);
2935 } break;
2936
2937 case 0x10:
2938 // kind: type in extends clause of class or interface declaration
2939 // or in implements clause of interface declaration
2940 // location: ClassFile
2941
2942 {
2943 // struct:
2944 // supertype_target {
2945 // u2 supertype_index;
2946 // }
2947 //
2948 if ((byte_i_ref + 2) > type_annotations_typeArray->length()) {
2949 log_debug(redefine, class, annotation)("length() is too small for a supertype_target");
2950 return false;
2951 }
2952
2953 u2 supertype_index = Bytes::get_Java_u2((address)
2954 type_annotations_typeArray->adr_at(byte_i_ref));
2955 byte_i_ref += 2;
2956
2957 log_debug(redefine, class, annotation)("supertype_target: supertype_index=%d", supertype_index);
2958 } break;
2959
2960 case 0x11:
2961 // kind: type in bound of type parameter declaration of generic class or interface
2962 // location: ClassFile
2963 case 0x12:
2964 // kind: type in bound of type parameter declaration of generic method or constructor
2965 // location: method_info
2966
2967 {
2968 // struct:
2969 // type_parameter_bound_target {
2970 // u1 type_parameter_index;
2971 // u1 bound_index;
2972 // }
2973 //
2974 if ((byte_i_ref + 2) > type_annotations_typeArray->length()) {
2975 log_debug(redefine, class, annotation)("length() is too small for a type_parameter_bound_target");
2976 return false;
2977 }
2978
2979 u1 type_parameter_index = type_annotations_typeArray->at(byte_i_ref);
2980 byte_i_ref += 1;
2981 u1 bound_index = type_annotations_typeArray->at(byte_i_ref);
2982 byte_i_ref += 1;
2983
2984 log_debug(redefine, class, annotation)
2985 ("type_parameter_bound_target: type_parameter_index=%d, bound_index=%d", type_parameter_index, bound_index);
2986 } break;
2987
2988 case 0x13:
2989 // kind: type in field declaration
2990 // location: field_info
2991 case 0x14:
2992 // kind: return type of method, or type of newly constructed object
2993 // location: method_info
2994 case 0x15:
2995 // kind: receiver type of method or constructor
2996 // location: method_info
2997
2998 {
2999 // struct:
3000 // empty_target {
3001 // }
3002 //
3003 log_debug(redefine, class, annotation)("empty_target");
3004 } break;
3005
3006 case 0x16:
3007 // kind: type in formal parameter declaration of method, constructor, or lambda expression
3008 // location: method_info
3009
3010 {
3011 // struct:
3012 // formal_parameter_target {
3013 // u1 formal_parameter_index;
3014 // }
3015 //
3016 if ((byte_i_ref + 1) > type_annotations_typeArray->length()) {
3017 log_debug(redefine, class, annotation)("length() is too small for a formal_parameter_target");
3018 return false;
3019 }
3020
3021 u1 formal_parameter_index = type_annotations_typeArray->at(byte_i_ref);
3022 byte_i_ref += 1;
3023
3024 log_debug(redefine, class, annotation)
3025 ("formal_parameter_target: formal_parameter_index=%d", formal_parameter_index);
3026 } break;
3027
3028 case 0x17:
3029 // kind: type in throws clause of method or constructor
3030 // location: method_info
3031
3032 {
3033 // struct:
3034 // throws_target {
3035 // u2 throws_type_index
3036 // }
3037 //
3038 if ((byte_i_ref + 2) > type_annotations_typeArray->length()) {
3039 log_debug(redefine, class, annotation)("length() is too small for a throws_target");
3040 return false;
3041 }
3042
3043 u2 throws_type_index = Bytes::get_Java_u2((address)
3044 type_annotations_typeArray->adr_at(byte_i_ref));
3045 byte_i_ref += 2;
3046
3047 log_debug(redefine, class, annotation)("throws_target: throws_type_index=%d", throws_type_index);
3048 } break;
3049
3050 case 0x40:
3051 // kind: type in local variable declaration
3052 // location: Code
3053 case 0x41:
3054 // kind: type in resource variable declaration
3055 // location: Code
3056
3057 {
3058 // struct:
3059 // localvar_target {
3060 // u2 table_length;
3061 // struct {
3062 // u2 start_pc;
3063 // u2 length;
3064 // u2 index;
3065 // } table[table_length];
3066 // }
3067 //
3068 if ((byte_i_ref + 2) > type_annotations_typeArray->length()) {
3069 // not enough room for a table_length let alone the rest of a localvar_target
3070 log_debug(redefine, class, annotation)("length() is too small for a localvar_target table_length");
3071 return false;
3072 }
3073
3074 u2 table_length = Bytes::get_Java_u2((address)
3075 type_annotations_typeArray->adr_at(byte_i_ref));
3076 byte_i_ref += 2;
3077
3078 log_debug(redefine, class, annotation)("localvar_target: table_length=%d", table_length);
3079
3080 int table_struct_size = 2 + 2 + 2; // 3 u2 variables per table entry
3081 int table_size = table_length * table_struct_size;
3082
3083 if ((byte_i_ref + table_size) > type_annotations_typeArray->length()) {
3084 // not enough room for a table
3085 log_debug(redefine, class, annotation)("length() is too small for a table array of length %d", table_length);
3086 return false;
3087 }
3088
3089 // Skip over table
3090 byte_i_ref += table_size;
3091 } break;
3092
3093 case 0x42:
3094 // kind: type in exception parameter declaration
3095 // location: Code
3096
3097 {
3098 // struct:
3099 // catch_target {
3100 // u2 exception_table_index;
3101 // }
3102 //
3103 if ((byte_i_ref + 2) > type_annotations_typeArray->length()) {
3104 log_debug(redefine, class, annotation)("length() is too small for a catch_target");
3105 return false;
3106 }
3107
3108 u2 exception_table_index = Bytes::get_Java_u2((address)
3109 type_annotations_typeArray->adr_at(byte_i_ref));
3110 byte_i_ref += 2;
3111
3112 log_debug(redefine, class, annotation)("catch_target: exception_table_index=%d", exception_table_index);
3113 } break;
3114
3115 case 0x43:
3116 // kind: type in instanceof expression
3117 // location: Code
3118 case 0x44:
3119 // kind: type in new expression
3120 // location: Code
3121 case 0x45:
3122 // kind: type in method reference expression using ::new
3123 // location: Code
3124 case 0x46:
3125 // kind: type in method reference expression using ::Identifier
3126 // location: Code
3127
3128 {
3129 // struct:
3130 // offset_target {
3131 // u2 offset;
3132 // }
3133 //
3134 if ((byte_i_ref + 2) > type_annotations_typeArray->length()) {
3135 log_debug(redefine, class, annotation)("length() is too small for a offset_target");
3136 return false;
3137 }
3138
3139 u2 offset = Bytes::get_Java_u2((address)
3140 type_annotations_typeArray->adr_at(byte_i_ref));
3141 byte_i_ref += 2;
3142
3143 log_debug(redefine, class, annotation)("offset_target: offset=%d", offset);
3144 } break;
3145
3146 case 0x47:
3147 // kind: type in cast expression
3148 // location: Code
3149 case 0x48:
3150 // kind: type argument for generic constructor in new expression or
3151 // explicit constructor invocation statement
3152 // location: Code
3153 case 0x49:
3154 // kind: type argument for generic method in method invocation expression
3155 // location: Code
3156 case 0x4A:
3157 // kind: type argument for generic constructor in method reference expression using ::new
3158 // location: Code
3159 case 0x4B:
3160 // kind: type argument for generic method in method reference expression using ::Identifier
3161 // location: Code
3162
3163 {
3164 // struct:
3165 // type_argument_target {
3166 // u2 offset;
3167 // u1 type_argument_index;
3168 // }
3169 //
3170 if ((byte_i_ref + 3) > type_annotations_typeArray->length()) {
3171 log_debug(redefine, class, annotation)("length() is too small for a type_argument_target");
3172 return false;
3173 }
3174
3175 u2 offset = Bytes::get_Java_u2((address)
3176 type_annotations_typeArray->adr_at(byte_i_ref));
3177 byte_i_ref += 2;
3178 u1 type_argument_index = type_annotations_typeArray->at(byte_i_ref);
3179 byte_i_ref += 1;
3180
3181 log_debug(redefine, class, annotation)
3182 ("type_argument_target: offset=%d, type_argument_index=%d", offset, type_argument_index);
3183 } break;
3184
3185 default:
3186 log_debug(redefine, class, annotation)("unknown target_type");
3187 #ifdef ASSERT
3188 ShouldNotReachHere();
3189 #endif
3190 return false;
3191 }
3192
3193 return true;
3194 } // end skip_type_annotation_target()
3195
3196
3197 // Read, verify and skip over the type_path part so that rewriting
3198 // can continue in the later parts of the struct.
3199 //
3200 // type_path {
3201 // u1 path_length;
3202 // {
3203 // u1 type_path_kind;
3204 // u1 type_argument_index;
3205 // } path[path_length];
3206 // }
3207 //
3208 bool VM_RedefineClasses::skip_type_annotation_type_path(
3209 AnnotationArray* type_annotations_typeArray, int &byte_i_ref) {
3210
3211 if ((byte_i_ref + 1) > type_annotations_typeArray->length()) {
3212 // not enough room for a path_length let alone the rest of the type_path
3213 log_debug(redefine, class, annotation)("length() is too small for a type_path");
3214 return false;
3215 }
3216
3217 u1 path_length = type_annotations_typeArray->at(byte_i_ref);
3218 byte_i_ref += 1;
3219
3220 log_debug(redefine, class, annotation)("type_path: path_length=%d", path_length);
3221
3222 int calc_path_length = 0;
3223 for (; calc_path_length < path_length; calc_path_length++) {
3224 if ((byte_i_ref + 1 + 1) > type_annotations_typeArray->length()) {
3225 // not enough room for a path
3226 log_debug(redefine, class, annotation)
3227 ("length() is too small for path entry %d of %d", calc_path_length, path_length);
3228 return false;
3229 }
3230
3231 u1 type_path_kind = type_annotations_typeArray->at(byte_i_ref);
3232 byte_i_ref += 1;
3233 u1 type_argument_index = type_annotations_typeArray->at(byte_i_ref);
3234 byte_i_ref += 1;
3235
3236 log_debug(redefine, class, annotation)
3237 ("type_path: path[%d]: type_path_kind=%d, type_argument_index=%d",
3238 calc_path_length, type_path_kind, type_argument_index);
3239
3240 if (type_path_kind > 3 || (type_path_kind != 3 && type_argument_index != 0)) {
3241 // not enough room for a path
3242 log_debug(redefine, class, annotation)("inconsistent type_path values");
3243 return false;
3244 }
3245 }
3246 assert(path_length == calc_path_length, "sanity check");
3247
3248 return true;
3249 } // end skip_type_annotation_type_path()
3250
3251
3252 // Rewrite constant pool references in the method's stackmap table.
3253 // These "structures" are adapted from the StackMapTable_attribute that
3254 // is described in section 4.8.4 of the 6.0 version of the VM spec
3255 // (dated 2005.10.26):
3256 // file:///net/quincunx.sfbay/export/gbracha/ClassFile-Java6.pdf
3257 //
3258 // stack_map {
3259 // u2 number_of_entries;
3260 // stack_map_frame entries[number_of_entries];
3261 // }
3262 //
3263 void VM_RedefineClasses::rewrite_cp_refs_in_stack_map_table(
3264 const methodHandle& method) {
3265
3266 if (!method->has_stackmap_table()) {
3267 return;
3268 }
3269
3270 AnnotationArray* stackmap_data = method->stackmap_data();
3271 address stackmap_p = (address)stackmap_data->adr_at(0);
3272 address stackmap_end = stackmap_p + stackmap_data->length();
3273
3274 assert(stackmap_p + 2 <= stackmap_end, "no room for number_of_entries");
3275 u2 number_of_entries = Bytes::get_Java_u2(stackmap_p);
3276 stackmap_p += 2;
3277
3278 log_debug(redefine, class, stackmap)("number_of_entries=%u", number_of_entries);
3279
3280 // walk through each stack_map_frame
3281 u2 calc_number_of_entries = 0;
3282 for (; calc_number_of_entries < number_of_entries; calc_number_of_entries++) {
3283 // The stack_map_frame structure is a u1 frame_type followed by
3284 // 0 or more bytes of data:
3285 //
3286 // union stack_map_frame {
3287 // same_frame;
3288 // same_locals_1_stack_item_frame;
3289 // same_locals_1_stack_item_frame_extended;
3290 // chop_frame;
3291 // same_frame_extended;
3292 // append_frame;
3293 // full_frame;
3294 // }
3295
3296 assert(stackmap_p + 1 <= stackmap_end, "no room for frame_type");
3297 u1 frame_type = *stackmap_p;
3298 stackmap_p++;
3299
3300 // same_frame {
3301 // u1 frame_type = SAME; /* 0-63 */
3302 // }
3303 if (frame_type <= 63) {
3304 // nothing more to do for same_frame
3305 }
3306
3307 // same_locals_1_stack_item_frame {
3308 // u1 frame_type = SAME_LOCALS_1_STACK_ITEM; /* 64-127 */
3309 // verification_type_info stack[1];
3310 // }
3311 else if (frame_type >= 64 && frame_type <= 127) {
3312 rewrite_cp_refs_in_verification_type_info(stackmap_p, stackmap_end,
3313 calc_number_of_entries, frame_type);
3314 }
3315
3316 // reserved for future use
3317 else if (frame_type >= 128 && frame_type <= 246) {
3318 // nothing more to do for reserved frame_types
3319 }
3320
3321 // same_locals_1_stack_item_frame_extended {
3322 // u1 frame_type = SAME_LOCALS_1_STACK_ITEM_EXTENDED; /* 247 */
3323 // u2 offset_delta;
3324 // verification_type_info stack[1];
3325 // }
3326 else if (frame_type == 247) {
3327 stackmap_p += 2;
3328 rewrite_cp_refs_in_verification_type_info(stackmap_p, stackmap_end,
3329 calc_number_of_entries, frame_type);
3330 }
3331
3332 // chop_frame {
3333 // u1 frame_type = CHOP; /* 248-250 */
3334 // u2 offset_delta;
3335 // }
3336 else if (frame_type >= 248 && frame_type <= 250) {
3337 stackmap_p += 2;
3338 }
3339
3340 // same_frame_extended {
3341 // u1 frame_type = SAME_FRAME_EXTENDED; /* 251*/
3342 // u2 offset_delta;
3343 // }
3344 else if (frame_type == 251) {
3345 stackmap_p += 2;
3346 }
3347
3348 // append_frame {
3349 // u1 frame_type = APPEND; /* 252-254 */
3350 // u2 offset_delta;
3351 // verification_type_info locals[frame_type - 251];
3352 // }
3353 else if (frame_type >= 252 && frame_type <= 254) {
3354 assert(stackmap_p + 2 <= stackmap_end,
3355 "no room for offset_delta");
3356 stackmap_p += 2;
3357 u1 len = frame_type - 251;
3358 for (u1 i = 0; i < len; i++) {
3359 rewrite_cp_refs_in_verification_type_info(stackmap_p, stackmap_end,
3360 calc_number_of_entries, frame_type);
3361 }
3362 }
3363
3364 // full_frame {
3365 // u1 frame_type = FULL_FRAME; /* 255 */
3366 // u2 offset_delta;
3367 // u2 number_of_locals;
3368 // verification_type_info locals[number_of_locals];
3369 // u2 number_of_stack_items;
3370 // verification_type_info stack[number_of_stack_items];
3371 // }
3372 else if (frame_type == 255) {
3373 assert(stackmap_p + 2 + 2 <= stackmap_end,
3374 "no room for smallest full_frame");
3375 stackmap_p += 2;
3376
3377 u2 number_of_locals = Bytes::get_Java_u2(stackmap_p);
3378 stackmap_p += 2;
3379
3380 for (u2 locals_i = 0; locals_i < number_of_locals; locals_i++) {
3381 rewrite_cp_refs_in_verification_type_info(stackmap_p, stackmap_end,
3382 calc_number_of_entries, frame_type);
3383 }
3384
3385 // Use the largest size for the number_of_stack_items, but only get
3386 // the right number of bytes.
3387 u2 number_of_stack_items = Bytes::get_Java_u2(stackmap_p);
3388 stackmap_p += 2;
3389
3390 for (u2 stack_i = 0; stack_i < number_of_stack_items; stack_i++) {
3391 rewrite_cp_refs_in_verification_type_info(stackmap_p, stackmap_end,
3392 calc_number_of_entries, frame_type);
3393 }
3394 }
3395 } // end while there is a stack_map_frame
3396 assert(number_of_entries == calc_number_of_entries, "sanity check");
3397 } // end rewrite_cp_refs_in_stack_map_table()
3398
3399
3400 // Rewrite constant pool references in the verification type info
3401 // portion of the method's stackmap table. These "structures" are
3402 // adapted from the StackMapTable_attribute that is described in
3403 // section 4.8.4 of the 6.0 version of the VM spec (dated 2005.10.26):
3404 // file:///net/quincunx.sfbay/export/gbracha/ClassFile-Java6.pdf
3405 //
3406 // The verification_type_info structure is a u1 tag followed by 0 or
3407 // more bytes of data:
3408 //
3409 // union verification_type_info {
3410 // Top_variable_info;
3411 // Integer_variable_info;
3412 // Float_variable_info;
3413 // Long_variable_info;
3414 // Double_variable_info;
3415 // Null_variable_info;
3416 // UninitializedThis_variable_info;
3417 // Object_variable_info;
3418 // Uninitialized_variable_info;
3419 // }
3420 //
3421 void VM_RedefineClasses::rewrite_cp_refs_in_verification_type_info(
3422 address& stackmap_p_ref, address stackmap_end, u2 frame_i,
3423 u1 frame_type) {
3424
3425 assert(stackmap_p_ref + 1 <= stackmap_end, "no room for tag");
3426 u1 tag = *stackmap_p_ref;
3427 stackmap_p_ref++;
3428
3429 switch (tag) {
3430 // Top_variable_info {
3431 // u1 tag = ITEM_Top; /* 0 */
3432 // }
3433 // verificationType.hpp has zero as ITEM_Bogus instead of ITEM_Top
3434 case 0: // fall through
3435
3436 // Integer_variable_info {
3437 // u1 tag = ITEM_Integer; /* 1 */
3438 // }
3439 case ITEM_Integer: // fall through
3440
3441 // Float_variable_info {
3442 // u1 tag = ITEM_Float; /* 2 */
3443 // }
3444 case ITEM_Float: // fall through
3445
3446 // Double_variable_info {
3447 // u1 tag = ITEM_Double; /* 3 */
3448 // }
3449 case ITEM_Double: // fall through
3450
3451 // Long_variable_info {
3452 // u1 tag = ITEM_Long; /* 4 */
3453 // }
3454 case ITEM_Long: // fall through
3455
3456 // Null_variable_info {
3457 // u1 tag = ITEM_Null; /* 5 */
3458 // }
3459 case ITEM_Null: // fall through
3460
3461 // UninitializedThis_variable_info {
3462 // u1 tag = ITEM_UninitializedThis; /* 6 */
3463 // }
3464 case ITEM_UninitializedThis:
3465 // nothing more to do for the above tag types
3466 break;
3467
3468 // Object_variable_info {
3469 // u1 tag = ITEM_Object; /* 7 */
3470 // u2 cpool_index;
3471 // }
3472 case ITEM_Object:
3473 {
3474 assert(stackmap_p_ref + 2 <= stackmap_end, "no room for cpool_index");
3475 u2 cpool_index = Bytes::get_Java_u2(stackmap_p_ref);
3476 u2 new_cp_index = find_new_index(cpool_index);
3477 if (new_cp_index != 0) {
3478 log_debug(redefine, class, stackmap)("mapped old cpool_index=%d", cpool_index);
3479 Bytes::put_Java_u2(stackmap_p_ref, new_cp_index);
3480 cpool_index = new_cp_index;
3481 }
3482 stackmap_p_ref += 2;
3483
3484 log_debug(redefine, class, stackmap)
3485 ("frame_i=%u, frame_type=%u, cpool_index=%d", frame_i, frame_type, cpool_index);
3486 } break;
3487
3488 // Uninitialized_variable_info {
3489 // u1 tag = ITEM_Uninitialized; /* 8 */
3490 // u2 offset;
3491 // }
3492 case ITEM_Uninitialized:
3493 assert(stackmap_p_ref + 2 <= stackmap_end, "no room for offset");
3494 stackmap_p_ref += 2;
3495 break;
3496
3497 default:
3498 log_debug(redefine, class, stackmap)("frame_i=%u, frame_type=%u, bad tag=0x%x", frame_i, frame_type, tag);
3499 ShouldNotReachHere();
3500 break;
3501 } // end switch (tag)
3502 } // end rewrite_cp_refs_in_verification_type_info()
3503
3504
3505 // Change the constant pool associated with klass scratch_class to scratch_cp.
3506 // scratch_cp_length elements are copied from scratch_cp to a smaller constant pool
3507 // and the smaller constant pool is associated with scratch_class.
3508 void VM_RedefineClasses::set_new_constant_pool(
3509 ClassLoaderData* loader_data,
3510 InstanceKlass* scratch_class, constantPoolHandle scratch_cp,
3511 int scratch_cp_length, TRAPS) {
3512 assert(scratch_cp->length() >= scratch_cp_length, "sanity check");
3513
3514 // scratch_cp is a merged constant pool and has enough space for a
3515 // worst case merge situation. We want to associate the minimum
3516 // sized constant pool with the klass to save space.
3517 ConstantPool* cp = ConstantPool::allocate(loader_data, scratch_cp_length, CHECK);
3518 constantPoolHandle smaller_cp(THREAD, cp);
3519
3520 // preserve version() value in the smaller copy
3521 int version = scratch_cp->version();
3522 assert(version != 0, "sanity check");
3523 smaller_cp->set_version(version);
3524
3525 // attach klass to new constant pool
3526 // reference to the cp holder is needed for copy_operands()
3527 smaller_cp->set_pool_holder(scratch_class);
3528
3529 smaller_cp->copy_fields(scratch_cp());
3530
3531 scratch_cp->copy_cp_to(1, scratch_cp_length - 1, smaller_cp, 1, THREAD);
3532 if (HAS_PENDING_EXCEPTION) {
3533 // Exception is handled in the caller
3534 loader_data->add_to_deallocate_list(smaller_cp());
3535 return;
3536 }
3537 scratch_cp = smaller_cp;
3538
3539 // attach new constant pool to klass
3540 scratch_class->set_constants(scratch_cp());
3541 scratch_cp->initialize_unresolved_klasses(loader_data, CHECK);
3542
3543 int i; // for portability
3544
3545 // update each field in klass to use new constant pool indices as needed
3546 for (JavaFieldStream fs(scratch_class); !fs.done(); fs.next()) {
3547 jshort cur_index = fs.name_index();
3548 jshort new_index = find_new_index(cur_index);
3549 if (new_index != 0) {
3550 log_trace(redefine, class, constantpool)("field-name_index change: %d to %d", cur_index, new_index);
3551 fs.set_name_index(new_index);
3552 }
3553 cur_index = fs.signature_index();
3554 new_index = find_new_index(cur_index);
3555 if (new_index != 0) {
3556 log_trace(redefine, class, constantpool)("field-signature_index change: %d to %d", cur_index, new_index);
3557 fs.set_signature_index(new_index);
3558 }
3559 cur_index = fs.initval_index();
3560 new_index = find_new_index(cur_index);
3561 if (new_index != 0) {
3562 log_trace(redefine, class, constantpool)("field-initval_index change: %d to %d", cur_index, new_index);
3563 fs.set_initval_index(new_index);
3564 }
3565 cur_index = fs.generic_signature_index();
3566 new_index = find_new_index(cur_index);
3567 if (new_index != 0) {
3568 log_trace(redefine, class, constantpool)("field-generic_signature change: %d to %d", cur_index, new_index);
3569 fs.set_generic_signature_index(new_index);
3570 }
3571 } // end for each field
3572
3573 // Update constant pool indices in the inner classes info to use
3574 // new constant indices as needed. The inner classes info is a
3575 // quadruple:
3576 // (inner_class_info, outer_class_info, inner_name, inner_access_flags)
3577 InnerClassesIterator iter(scratch_class);
3578 for (; !iter.done(); iter.next()) {
3579 int cur_index = iter.inner_class_info_index();
3580 if (cur_index == 0) {
3581 continue; // JVM spec. allows null inner class refs so skip it
3582 }
3583 int new_index = find_new_index(cur_index);
3584 if (new_index != 0) {
3585 log_trace(redefine, class, constantpool)("inner_class_info change: %d to %d", cur_index, new_index);
3586 iter.set_inner_class_info_index(new_index);
3587 }
3588 cur_index = iter.outer_class_info_index();
3589 new_index = find_new_index(cur_index);
3590 if (new_index != 0) {
3591 log_trace(redefine, class, constantpool)("outer_class_info change: %d to %d", cur_index, new_index);
3592 iter.set_outer_class_info_index(new_index);
3593 }
3594 cur_index = iter.inner_name_index();
3595 new_index = find_new_index(cur_index);
3596 if (new_index != 0) {
3597 log_trace(redefine, class, constantpool)("inner_name change: %d to %d", cur_index, new_index);
3598 iter.set_inner_name_index(new_index);
3599 }
3600 } // end for each inner class
3601
3602 // Attach each method in klass to the new constant pool and update
3603 // to use new constant pool indices as needed:
3604 Array<Method*>* methods = scratch_class->methods();
3605 for (i = methods->length() - 1; i >= 0; i--) {
3606 methodHandle method(THREAD, methods->at(i));
3607 method->set_constants(scratch_cp());
3608
3609 int new_index = find_new_index(method->name_index());
3610 if (new_index != 0) {
3611 log_trace(redefine, class, constantpool)
3612 ("method-name_index change: %d to %d", method->name_index(), new_index);
3613 method->set_name_index(new_index);
3614 }
3615 new_index = find_new_index(method->signature_index());
3616 if (new_index != 0) {
3617 log_trace(redefine, class, constantpool)
3618 ("method-signature_index change: %d to %d", method->signature_index(), new_index);
3619 method->set_signature_index(new_index);
3620 }
3621 new_index = find_new_index(method->generic_signature_index());
3622 if (new_index != 0) {
3623 log_trace(redefine, class, constantpool)
3624 ("method-generic_signature_index change: %d to %d", method->generic_signature_index(), new_index);
3625 method->set_generic_signature_index(new_index);
3626 }
3627
3628 // Update constant pool indices in the method's checked exception
3629 // table to use new constant indices as needed.
3630 int cext_length = method->checked_exceptions_length();
3631 if (cext_length > 0) {
3632 CheckedExceptionElement * cext_table =
3633 method->checked_exceptions_start();
3634 for (int j = 0; j < cext_length; j++) {
3635 int cur_index = cext_table[j].class_cp_index;
3636 int new_index = find_new_index(cur_index);
3637 if (new_index != 0) {
3638 log_trace(redefine, class, constantpool)("cext-class_cp_index change: %d to %d", cur_index, new_index);
3639 cext_table[j].class_cp_index = (u2)new_index;
3640 }
3641 } // end for each checked exception table entry
3642 } // end if there are checked exception table entries
3643
3644 // Update each catch type index in the method's exception table
3645 // to use new constant pool indices as needed. The exception table
3646 // holds quadruple entries of the form:
3647 // (beg_bci, end_bci, handler_bci, klass_index)
3648
3649 ExceptionTable ex_table(method());
3650 int ext_length = ex_table.length();
3651
3652 for (int j = 0; j < ext_length; j ++) {
3653 int cur_index = ex_table.catch_type_index(j);
3654 int new_index = find_new_index(cur_index);
3655 if (new_index != 0) {
3656 log_trace(redefine, class, constantpool)("ext-klass_index change: %d to %d", cur_index, new_index);
3657 ex_table.set_catch_type_index(j, new_index);
3658 }
3659 } // end for each exception table entry
3660
3661 // Update constant pool indices in the method's local variable
3662 // table to use new constant indices as needed. The local variable
3663 // table hold sextuple entries of the form:
3664 // (start_pc, length, name_index, descriptor_index, signature_index, slot)
3665 int lvt_length = method->localvariable_table_length();
3666 if (lvt_length > 0) {
3667 LocalVariableTableElement * lv_table =
3668 method->localvariable_table_start();
3669 for (int j = 0; j < lvt_length; j++) {
3670 int cur_index = lv_table[j].name_cp_index;
3671 int new_index = find_new_index(cur_index);
3672 if (new_index != 0) {
3673 log_trace(redefine, class, constantpool)("lvt-name_cp_index change: %d to %d", cur_index, new_index);
3674 lv_table[j].name_cp_index = (u2)new_index;
3675 }
3676 cur_index = lv_table[j].descriptor_cp_index;
3677 new_index = find_new_index(cur_index);
3678 if (new_index != 0) {
3679 log_trace(redefine, class, constantpool)("lvt-descriptor_cp_index change: %d to %d", cur_index, new_index);
3680 lv_table[j].descriptor_cp_index = (u2)new_index;
3681 }
3682 cur_index = lv_table[j].signature_cp_index;
3683 new_index = find_new_index(cur_index);
3684 if (new_index != 0) {
3685 log_trace(redefine, class, constantpool)("lvt-signature_cp_index change: %d to %d", cur_index, new_index);
3686 lv_table[j].signature_cp_index = (u2)new_index;
3687 }
3688 } // end for each local variable table entry
3689 } // end if there are local variable table entries
3690
3691 // Update constant pool indices in the method's method_parameters.
3692 int mp_length = method->method_parameters_length();
3693 if (mp_length > 0) {
3694 MethodParametersElement* elem = method->method_parameters_start();
3695 for (int j = 0; j < mp_length; j++) {
3696 const int cp_index = elem[j].name_cp_index;
3697 const int new_cp_index = find_new_index(cp_index);
3698 if (new_cp_index != 0) {
3699 elem[j].name_cp_index = (u2)new_cp_index;
3700 }
3701 }
3702 }
3703
3704 rewrite_cp_refs_in_stack_map_table(method);
3705 } // end for each method
3706 } // end set_new_constant_pool()
3707
3708
3709 // Unevolving classes may point to methods of the_class directly
3710 // from their constant pool caches, itables, and/or vtables. We
3711 // use the ClassLoaderDataGraph::classes_do() facility and this helper
3712 // to fix up these pointers. MethodData also points to old methods and
3713 // must be cleaned.
3714
3715 // Adjust cpools and vtables closure
3716 void VM_RedefineClasses::AdjustAndCleanMetadata::do_klass(Klass* k) {
3717
3718 // This is a very busy routine. We don't want too much tracing
3719 // printed out.
3720 bool trace_name_printed = false;
3721
3722 // If the class being redefined is java.lang.Object, we need to fix all
3723 // array class vtables also. The _has_redefined_Object flag is global.
3724 // Once the java.lang.Object has been redefined (by the current or one
3725 // of the previous VM_RedefineClasses operations) we have to always
3726 // adjust method entries for array classes.
3727 if (k->is_array_klass() && _has_redefined_Object) {
3728 k->vtable().adjust_method_entries(&trace_name_printed);
3729
3730 } else if (k->is_instance_klass()) {
3731 HandleMark hm(_thread);
3732 InstanceKlass *ik = InstanceKlass::cast(k);
3733
3734 // Clean MethodData of this class's methods so they don't refer to
3735 // old methods that are no longer running.
3736 Array<Method*>* methods = ik->methods();
3737 int num_methods = methods->length();
3738 for (int index = 0; index < num_methods; ++index) {
3739 if (methods->at(index)->method_data() != NULL) {
3740 methods->at(index)->method_data()->clean_weak_method_links();
3741 }
3742 }
3743
3744 // Adjust all vtables, default methods and itables, to clean out old methods.
3745 ResourceMark rm(_thread);
3746 if (ik->vtable_length() > 0) {
3747 ik->vtable().adjust_method_entries(&trace_name_printed);
3748 ik->adjust_default_methods(&trace_name_printed);
3749 }
3750
3751 if (ik->itable_length() > 0) {
3752 ik->itable().adjust_method_entries(&trace_name_printed);
3753 }
3754
3755 // The constant pools in other classes (other_cp) can refer to
3756 // old methods. We have to update method information in
3757 // other_cp's cache. If other_cp has a previous version, then we
3758 // have to repeat the process for each previous version. The
3759 // constant pool cache holds the Method*s for non-virtual
3760 // methods and for virtual, final methods.
3761 //
3762 // Special case: if the current class is being redefined by the current
3763 // VM_RedefineClasses operation, then new_cp has already been attached
3764 // to the_class and old_cp has already been added as a previous version.
3765 // The new_cp doesn't have any cached references to old methods so it
3766 // doesn't need to be updated and we could optimize by skipping it.
3767 // However, the current class can be marked as being redefined by another
3768 // VM_RedefineClasses operation which has already executed its doit_prologue
3769 // and needs cpcache method entries adjusted. For simplicity, the cpcache
3770 // update is done unconditionally. It should result in doing nothing for
3771 // classes being redefined by the current VM_RedefineClasses operation.
3772 // Method entries in the previous version(s) are adjusted as well.
3773 ConstantPoolCache* cp_cache;
3774
3775 // this klass' constant pool cache may need adjustment
3776 ConstantPool* other_cp = ik->constants();
3777 cp_cache = other_cp->cache();
3778 if (cp_cache != NULL) {
3779 cp_cache->adjust_method_entries(&trace_name_printed);
3780 }
3781
3782 // the previous versions' constant pool caches may need adjustment
3783 for (InstanceKlass* pv_node = ik->previous_versions();
3784 pv_node != NULL;
3785 pv_node = pv_node->previous_versions()) {
3786 cp_cache = pv_node->constants()->cache();
3787 if (cp_cache != NULL) {
3788 cp_cache->adjust_method_entries(&trace_name_printed);
3789 }
3790 }
3791 }
3792 }
3793
3794 void VM_RedefineClasses::update_jmethod_ids() {
3795 for (int j = 0; j < _matching_methods_length; ++j) {
3796 Method* old_method = _matching_old_methods[j];
3797 jmethodID jmid = old_method->find_jmethod_id_or_null();
3798 if (jmid != NULL) {
3799 // There is a jmethodID, change it to point to the new method
3800 Method* new_method = _matching_new_methods[j];
3801 Method::change_method_associated_with_jmethod_id(jmid, new_method);
3802 assert(Method::resolve_jmethod_id(jmid) == _matching_new_methods[j],
3803 "should be replaced");
3804 }
3805 }
3806 }
3807
3808 int VM_RedefineClasses::check_methods_and_mark_as_obsolete() {
3809 int emcp_method_count = 0;
3810 int obsolete_count = 0;
3811 int old_index = 0;
3812 for (int j = 0; j < _matching_methods_length; ++j, ++old_index) {
3813 Method* old_method = _matching_old_methods[j];
3814 Method* new_method = _matching_new_methods[j];
3815 Method* old_array_method;
3816
3817 // Maintain an old_index into the _old_methods array by skipping
3818 // deleted methods
3819 while ((old_array_method = _old_methods->at(old_index)) != old_method) {
3820 ++old_index;
3821 }
3822
3823 if (MethodComparator::methods_EMCP(old_method, new_method)) {
3824 // The EMCP definition from JSR-163 requires the bytecodes to be
3825 // the same with the exception of constant pool indices which may
3826 // differ. However, the constants referred to by those indices
3827 // must be the same.
3828 //
3829 // We use methods_EMCP() for comparison since constant pool
3830 // merging can remove duplicate constant pool entries that were
3831 // present in the old method and removed from the rewritten new
3832 // method. A faster binary comparison function would consider the
3833 // old and new methods to be different when they are actually
3834 // EMCP.
3835 //
3836 // The old and new methods are EMCP and you would think that we
3837 // could get rid of one of them here and now and save some space.
3838 // However, the concept of EMCP only considers the bytecodes and
3839 // the constant pool entries in the comparison. Other things,
3840 // e.g., the line number table (LNT) or the local variable table
3841 // (LVT) don't count in the comparison. So the new (and EMCP)
3842 // method can have a new LNT that we need so we can't just
3843 // overwrite the new method with the old method.
3844 //
3845 // When this routine is called, we have already attached the new
3846 // methods to the_class so the old methods are effectively
3847 // overwritten. However, if an old method is still executing,
3848 // then the old method cannot be collected until sometime after
3849 // the old method call has returned. So the overwriting of old
3850 // methods by new methods will save us space except for those
3851 // (hopefully few) old methods that are still executing.
3852 //
3853 // A method refers to a ConstMethod* and this presents another
3854 // possible avenue to space savings. The ConstMethod* in the
3855 // new method contains possibly new attributes (LNT, LVT, etc).
3856 // At first glance, it seems possible to save space by replacing
3857 // the ConstMethod* in the old method with the ConstMethod*
3858 // from the new method. The old and new methods would share the
3859 // same ConstMethod* and we would save the space occupied by
3860 // the old ConstMethod*. However, the ConstMethod* contains
3861 // a back reference to the containing method. Sharing the
3862 // ConstMethod* between two methods could lead to confusion in
3863 // the code that uses the back reference. This would lead to
3864 // brittle code that could be broken in non-obvious ways now or
3865 // in the future.
3866 //
3867 // Another possibility is to copy the ConstMethod* from the new
3868 // method to the old method and then overwrite the new method with
3869 // the old method. Since the ConstMethod* contains the bytecodes
3870 // for the method embedded in the oop, this option would change
3871 // the bytecodes out from under any threads executing the old
3872 // method and make the thread's bcp invalid. Since EMCP requires
3873 // that the bytecodes be the same modulo constant pool indices, it
3874 // is straight forward to compute the correct new bcp in the new
3875 // ConstMethod* from the old bcp in the old ConstMethod*. The
3876 // time consuming part would be searching all the frames in all
3877 // of the threads to find all of the calls to the old method.
3878 //
3879 // It looks like we will have to live with the limited savings
3880 // that we get from effectively overwriting the old methods
3881 // when the new methods are attached to the_class.
3882
3883 // Count number of methods that are EMCP. The method will be marked
3884 // old but not obsolete if it is EMCP.
3885 emcp_method_count++;
3886
3887 // An EMCP method is _not_ obsolete. An obsolete method has a
3888 // different jmethodID than the current method. An EMCP method
3889 // has the same jmethodID as the current method. Having the
3890 // same jmethodID for all EMCP versions of a method allows for
3891 // a consistent view of the EMCP methods regardless of which
3892 // EMCP method you happen to have in hand. For example, a
3893 // breakpoint set in one EMCP method will work for all EMCP
3894 // versions of the method including the current one.
3895 } else {
3896 // mark obsolete methods as such
3897 old_method->set_is_obsolete();
3898 obsolete_count++;
3899
3900 // obsolete methods need a unique idnum so they become new entries in
3901 // the jmethodID cache in InstanceKlass
3902 assert(old_method->method_idnum() == new_method->method_idnum(), "must match");
3903 u2 num = InstanceKlass::cast(_the_class)->next_method_idnum();
3904 if (num != ConstMethod::UNSET_IDNUM) {
3905 old_method->set_method_idnum(num);
3906 }
3907
3908 // With tracing we try not to "yack" too much. The position of
3909 // this trace assumes there are fewer obsolete methods than
3910 // EMCP methods.
3911 if (log_is_enabled(Trace, redefine, class, obsolete, mark)) {
3912 ResourceMark rm;
3913 log_trace(redefine, class, obsolete, mark)
3914 ("mark %s(%s) as obsolete", old_method->name()->as_C_string(), old_method->signature()->as_C_string());
3915 }
3916 }
3917 old_method->set_is_old();
3918 }
3919 for (int i = 0; i < _deleted_methods_length; ++i) {
3920 Method* old_method = _deleted_methods[i];
3921
3922 assert(!old_method->has_vtable_index(),
3923 "cannot delete methods with vtable entries");;
3924
3925 // Mark all deleted methods as old, obsolete and deleted
3926 old_method->set_is_deleted();
3927 old_method->set_is_old();
3928 old_method->set_is_obsolete();
3929 ++obsolete_count;
3930 // With tracing we try not to "yack" too much. The position of
3931 // this trace assumes there are fewer obsolete methods than
3932 // EMCP methods.
3933 if (log_is_enabled(Trace, redefine, class, obsolete, mark)) {
3934 ResourceMark rm;
3935 log_trace(redefine, class, obsolete, mark)
3936 ("mark deleted %s(%s) as obsolete", old_method->name()->as_C_string(), old_method->signature()->as_C_string());
3937 }
3938 }
3939 assert((emcp_method_count + obsolete_count) == _old_methods->length(),
3940 "sanity check");
3941 log_trace(redefine, class, obsolete, mark)("EMCP_cnt=%d, obsolete_cnt=%d", emcp_method_count, obsolete_count);
3942 return emcp_method_count;
3943 }
3944
3945 // This internal class transfers the native function registration from old methods
3946 // to new methods. It is designed to handle both the simple case of unchanged
3947 // native methods and the complex cases of native method prefixes being added and/or
3948 // removed.
3949 // It expects only to be used during the VM_RedefineClasses op (a safepoint).
3950 //
3951 // This class is used after the new methods have been installed in "the_class".
3952 //
3953 // So, for example, the following must be handled. Where 'm' is a method and
3954 // a number followed by an underscore is a prefix.
3955 //
3956 // Old Name New Name
3957 // Simple transfer to new method m -> m
3958 // Add prefix m -> 1_m
3959 // Remove prefix 1_m -> m
3960 // Simultaneous add of prefixes m -> 3_2_1_m
3961 // Simultaneous removal of prefixes 3_2_1_m -> m
3962 // Simultaneous add and remove 1_m -> 2_m
3963 // Same, caused by prefix removal only 3_2_1_m -> 3_2_m
3964 //
3965 class TransferNativeFunctionRegistration {
3966 private:
3967 InstanceKlass* the_class;
3968 int prefix_count;
3969 char** prefixes;
3970
3971 // Recursively search the binary tree of possibly prefixed method names.
3972 // Iteration could be used if all agents were well behaved. Full tree walk is
3973 // more resilent to agents not cleaning up intermediate methods.
3974 // Branch at each depth in the binary tree is:
3975 // (1) without the prefix.
3976 // (2) with the prefix.
3977 // where 'prefix' is the prefix at that 'depth' (first prefix, second prefix,...)
3978 Method* search_prefix_name_space(int depth, char* name_str, size_t name_len,
3979 Symbol* signature) {
3980 TempNewSymbol name_symbol = SymbolTable::probe(name_str, (int)name_len);
3981 if (name_symbol != NULL) {
3982 Method* method = the_class->lookup_method(name_symbol, signature);
3983 if (method != NULL) {
3984 // Even if prefixed, intermediate methods must exist.
3985 if (method->is_native()) {
3986 // Wahoo, we found a (possibly prefixed) version of the method, return it.
3987 return method;
3988 }
3989 if (depth < prefix_count) {
3990 // Try applying further prefixes (other than this one).
3991 method = search_prefix_name_space(depth+1, name_str, name_len, signature);
3992 if (method != NULL) {
3993 return method; // found
3994 }
3995
3996 // Try adding this prefix to the method name and see if it matches
3997 // another method name.
3998 char* prefix = prefixes[depth];
3999 size_t prefix_len = strlen(prefix);
4000 size_t trial_len = name_len + prefix_len;
4001 char* trial_name_str = NEW_RESOURCE_ARRAY(char, trial_len + 1);
4002 strcpy(trial_name_str, prefix);
4003 strcat(trial_name_str, name_str);
4004 method = search_prefix_name_space(depth+1, trial_name_str, trial_len,
4005 signature);
4006 if (method != NULL) {
4007 // If found along this branch, it was prefixed, mark as such
4008 method->set_is_prefixed_native();
4009 return method; // found
4010 }
4011 }
4012 }
4013 }
4014 return NULL; // This whole branch bore nothing
4015 }
4016
4017 // Return the method name with old prefixes stripped away.
4018 char* method_name_without_prefixes(Method* method) {
4019 Symbol* name = method->name();
4020 char* name_str = name->as_utf8();
4021
4022 // Old prefixing may be defunct, strip prefixes, if any.
4023 for (int i = prefix_count-1; i >= 0; i--) {
4024 char* prefix = prefixes[i];
4025 size_t prefix_len = strlen(prefix);
4026 if (strncmp(prefix, name_str, prefix_len) == 0) {
4027 name_str += prefix_len;
4028 }
4029 }
4030 return name_str;
4031 }
4032
4033 // Strip any prefixes off the old native method, then try to find a
4034 // (possibly prefixed) new native that matches it.
4035 Method* strip_and_search_for_new_native(Method* method) {
4036 ResourceMark rm;
4037 char* name_str = method_name_without_prefixes(method);
4038 return search_prefix_name_space(0, name_str, strlen(name_str),
4039 method->signature());
4040 }
4041
4042 public:
4043
4044 // Construct a native method transfer processor for this class.
4045 TransferNativeFunctionRegistration(InstanceKlass* _the_class) {
4046 assert(SafepointSynchronize::is_at_safepoint(), "sanity check");
4047
4048 the_class = _the_class;
4049 prefixes = JvmtiExport::get_all_native_method_prefixes(&prefix_count);
4050 }
4051
4052 // Attempt to transfer any of the old or deleted methods that are native
4053 void transfer_registrations(Method** old_methods, int methods_length) {
4054 for (int j = 0; j < methods_length; j++) {
4055 Method* old_method = old_methods[j];
4056
4057 if (old_method->is_native() && old_method->has_native_function()) {
4058 Method* new_method = strip_and_search_for_new_native(old_method);
4059 if (new_method != NULL) {
4060 // Actually set the native function in the new method.
4061 // Redefine does not send events (except CFLH), certainly not this
4062 // behind the scenes re-registration.
4063 new_method->set_native_function(old_method->native_function(),
4064 !Method::native_bind_event_is_interesting);
4065 }
4066 }
4067 }
4068 }
4069 };
4070
4071 // Don't lose the association between a native method and its JNI function.
4072 void VM_RedefineClasses::transfer_old_native_function_registrations(InstanceKlass* the_class) {
4073 TransferNativeFunctionRegistration transfer(the_class);
4074 transfer.transfer_registrations(_deleted_methods, _deleted_methods_length);
4075 transfer.transfer_registrations(_matching_old_methods, _matching_methods_length);
4076 }
4077
4078 // Deoptimize all compiled code that depends on the classes redefined.
4079 //
4080 // If the can_redefine_classes capability is obtained in the onload
4081 // phase then the compiler has recorded all dependencies from startup.
4082 // In that case we need only deoptimize and throw away all compiled code
4083 // that depends on the class.
4084 //
4085 // If can_redefine_classes is obtained sometime after the onload
4086 // phase then the dependency information may be incomplete. In that case
4087 // the first call to RedefineClasses causes all compiled code to be
4088 // thrown away. As can_redefine_classes has been obtained then
4089 // all future compilations will record dependencies so second and
4090 // subsequent calls to RedefineClasses need only throw away code
4091 // that depends on the class.
4092 //
4093
4094 void VM_RedefineClasses::flush_dependent_code() {
4095 assert(SafepointSynchronize::is_at_safepoint(), "sanity check");
4096
4097 bool deopt_needed;
4098
4099 // This is the first redefinition, mark all the nmethods for deoptimization
4100 if (!JvmtiExport::all_dependencies_are_recorded()) {
4101 log_debug(redefine, class, nmethod)("Marked all nmethods for deopt");
4102 CodeCache::mark_all_nmethods_for_evol_deoptimization();
4103 deopt_needed = true;
4104 } else {
4105 int deopt = CodeCache::mark_dependents_for_evol_deoptimization();
4106 log_debug(redefine, class, nmethod)("Marked %d dependent nmethods for deopt", deopt);
4107 deopt_needed = (deopt != 0);
4108 }
4109
4110 if (deopt_needed) {
4111 CodeCache::flush_evol_dependents();
4112 }
4113
4114 // From now on we know that the dependency information is complete
4115 JvmtiExport::set_all_dependencies_are_recorded(true);
4116 }
4117
4118 void VM_RedefineClasses::compute_added_deleted_matching_methods() {
4119 Method* old_method;
4120 Method* new_method;
4121
4122 _matching_old_methods = NEW_RESOURCE_ARRAY(Method*, _old_methods->length());
4123 _matching_new_methods = NEW_RESOURCE_ARRAY(Method*, _old_methods->length());
4124 _added_methods = NEW_RESOURCE_ARRAY(Method*, _new_methods->length());
4125 _deleted_methods = NEW_RESOURCE_ARRAY(Method*, _old_methods->length());
4126
4127 _matching_methods_length = 0;
4128 _deleted_methods_length = 0;
4129 _added_methods_length = 0;
4130
4131 int nj = 0;
4132 int oj = 0;
4133 while (true) {
4134 if (oj >= _old_methods->length()) {
4135 if (nj >= _new_methods->length()) {
4136 break; // we've looked at everything, done
4137 }
4138 // New method at the end
4139 new_method = _new_methods->at(nj);
4140 _added_methods[_added_methods_length++] = new_method;
4141 ++nj;
4142 } else if (nj >= _new_methods->length()) {
4143 // Old method, at the end, is deleted
4144 old_method = _old_methods->at(oj);
4145 _deleted_methods[_deleted_methods_length++] = old_method;
4146 ++oj;
4147 } else {
4148 old_method = _old_methods->at(oj);
4149 new_method = _new_methods->at(nj);
4150 if (old_method->name() == new_method->name()) {
4151 if (old_method->signature() == new_method->signature()) {
4152 _matching_old_methods[_matching_methods_length ] = old_method;
4153 _matching_new_methods[_matching_methods_length++] = new_method;
4154 ++nj;
4155 ++oj;
4156 } else {
4157 // added overloaded have already been moved to the end,
4158 // so this is a deleted overloaded method
4159 _deleted_methods[_deleted_methods_length++] = old_method;
4160 ++oj;
4161 }
4162 } else { // names don't match
4163 if (old_method->name()->fast_compare(new_method->name()) > 0) {
4164 // new method
4165 _added_methods[_added_methods_length++] = new_method;
4166 ++nj;
4167 } else {
4168 // deleted method
4169 _deleted_methods[_deleted_methods_length++] = old_method;
4170 ++oj;
4171 }
4172 }
4173 }
4174 }
4175 assert(_matching_methods_length + _deleted_methods_length == _old_methods->length(), "sanity");
4176 assert(_matching_methods_length + _added_methods_length == _new_methods->length(), "sanity");
4177 }
4178
4179
4180 void VM_RedefineClasses::swap_annotations(InstanceKlass* the_class,
4181 InstanceKlass* scratch_class) {
4182 // Swap annotation fields values
4183 Annotations* old_annotations = the_class->annotations();
4184 the_class->set_annotations(scratch_class->annotations());
4185 scratch_class->set_annotations(old_annotations);
4186 }
4187
4188
4189 // Install the redefinition of a class:
4190 // - house keeping (flushing breakpoints and caches, deoptimizing
4191 // dependent compiled code)
4192 // - replacing parts in the_class with parts from scratch_class
4193 // - adding a weak reference to track the obsolete but interesting
4194 // parts of the_class
4195 // - adjusting constant pool caches and vtables in other classes
4196 // that refer to methods in the_class. These adjustments use the
4197 // ClassLoaderDataGraph::classes_do() facility which only allows
4198 // a helper method to be specified. The interesting parameters
4199 // that we would like to pass to the helper method are saved in
4200 // static global fields in the VM operation.
4201 void VM_RedefineClasses::redefine_single_class(Thread* current, jclass the_jclass,
4202 InstanceKlass* scratch_class) {
4203
4204 HandleMark hm(current); // make sure handles from this call are freed
4205
4206 if (log_is_enabled(Info, redefine, class, timer)) {
4207 _timer_rsc_phase1.start();
4208 }
4209
4210 InstanceKlass* the_class = get_ik(the_jclass);
4211
4212 // Set a flag to control and optimize adjusting method entries
4213 _has_redefined_Object |= the_class == vmClasses::Object_klass();
4214
4215 // Remove all breakpoints in methods of this class
4216 JvmtiBreakpoints& jvmti_breakpoints = JvmtiCurrentBreakpoints::get_jvmti_breakpoints();
4217 jvmti_breakpoints.clearall_in_class_at_safepoint(the_class);
4218
4219 _old_methods = the_class->methods();
4220 _new_methods = scratch_class->methods();
4221 _the_class = the_class;
4222 compute_added_deleted_matching_methods();
4223 update_jmethod_ids();
4224
4225 _any_class_has_resolved_methods = the_class->has_resolved_methods() || _any_class_has_resolved_methods;
4226
4227 // Attach new constant pool to the original klass. The original
4228 // klass still refers to the old constant pool (for now).
4229 scratch_class->constants()->set_pool_holder(the_class);
4230
4231 #if 0
4232 // In theory, with constant pool merging in place we should be able
4233 // to save space by using the new, merged constant pool in place of
4234 // the old constant pool(s). By "pool(s)" I mean the constant pool in
4235 // the klass version we are replacing now and any constant pool(s) in
4236 // previous versions of klass. Nice theory, doesn't work in practice.
4237 // When this code is enabled, even simple programs throw NullPointer
4238 // exceptions. I'm guessing that this is caused by some constant pool
4239 // cache difference between the new, merged constant pool and the
4240 // constant pool that was just being used by the klass. I'm keeping
4241 // this code around to archive the idea, but the code has to remain
4242 // disabled for now.
4243
4244 // Attach each old method to the new constant pool. This can be
4245 // done here since we are past the bytecode verification and
4246 // constant pool optimization phases.
4247 for (int i = _old_methods->length() - 1; i >= 0; i--) {
4248 Method* method = _old_methods->at(i);
4249 method->set_constants(scratch_class->constants());
4250 }
4251
4252 // NOTE: this doesn't work because you can redefine the same class in two
4253 // threads, each getting their own constant pool data appended to the
4254 // original constant pool. In order for the new methods to work when they
4255 // become old methods, they need to keep their updated copy of the constant pool.
4256
4257 {
4258 // walk all previous versions of the klass
4259 InstanceKlass *ik = the_class;
4260 PreviousVersionWalker pvw(ik);
4261 do {
4262 ik = pvw.next_previous_version();
4263 if (ik != NULL) {
4264
4265 // attach previous version of klass to the new constant pool
4266 ik->set_constants(scratch_class->constants());
4267
4268 // Attach each method in the previous version of klass to the
4269 // new constant pool
4270 Array<Method*>* prev_methods = ik->methods();
4271 for (int i = prev_methods->length() - 1; i >= 0; i--) {
4272 Method* method = prev_methods->at(i);
4273 method->set_constants(scratch_class->constants());
4274 }
4275 }
4276 } while (ik != NULL);
4277 }
4278 #endif
4279
4280 // Replace methods and constantpool
4281 the_class->set_methods(_new_methods);
4282 scratch_class->set_methods(_old_methods); // To prevent potential GCing of the old methods,
4283 // and to be able to undo operation easily.
4284
4285 Array<int>* old_ordering = the_class->method_ordering();
4286 the_class->set_method_ordering(scratch_class->method_ordering());
4287 scratch_class->set_method_ordering(old_ordering);
4288
4289 ConstantPool* old_constants = the_class->constants();
4290 the_class->set_constants(scratch_class->constants());
4291 scratch_class->set_constants(old_constants); // See the previous comment.
4292 #if 0
4293 // We are swapping the guts of "the new class" with the guts of "the
4294 // class". Since the old constant pool has just been attached to "the
4295 // new class", it seems logical to set the pool holder in the old
4296 // constant pool also. However, doing this will change the observable
4297 // class hierarchy for any old methods that are still executing. A
4298 // method can query the identity of its "holder" and this query uses
4299 // the method's constant pool link to find the holder. The change in
4300 // holding class from "the class" to "the new class" can confuse
4301 // things.
4302 //
4303 // Setting the old constant pool's holder will also cause
4304 // verification done during vtable initialization below to fail.
4305 // During vtable initialization, the vtable's class is verified to be
4306 // a subtype of the method's holder. The vtable's class is "the
4307 // class" and the method's holder is gotten from the constant pool
4308 // link in the method itself. For "the class"'s directly implemented
4309 // methods, the method holder is "the class" itself (as gotten from
4310 // the new constant pool). The check works fine in this case. The
4311 // check also works fine for methods inherited from super classes.
4312 //
4313 // Miranda methods are a little more complicated. A miranda method is
4314 // provided by an interface when the class implementing the interface
4315 // does not provide its own method. These interfaces are implemented
4316 // internally as an InstanceKlass. These special instanceKlasses
4317 // share the constant pool of the class that "implements" the
4318 // interface. By sharing the constant pool, the method holder of a
4319 // miranda method is the class that "implements" the interface. In a
4320 // non-redefine situation, the subtype check works fine. However, if
4321 // the old constant pool's pool holder is modified, then the check
4322 // fails because there is no class hierarchy relationship between the
4323 // vtable's class and "the new class".
4324
4325 old_constants->set_pool_holder(scratch_class());
4326 #endif
4327
4328 // track number of methods that are EMCP for add_previous_version() call below
4329 int emcp_method_count = check_methods_and_mark_as_obsolete();
4330 transfer_old_native_function_registrations(the_class);
4331
4332 if (scratch_class->get_cached_class_file() != the_class->get_cached_class_file()) {
4333 // 1. the_class doesn't have a cache yet, scratch_class does have a cache.
4334 // 2. The same class can be present twice in the scratch classes list or there
4335 // are multiple concurrent RetransformClasses calls on different threads.
4336 // the_class and scratch_class have the same cached bytes, but different buffers.
4337 // In such cases we need to deallocate one of the buffers.
4338 // 3. RedefineClasses and the_class has cached bytes from a previous transformation.
4339 // In the case we need to use class bytes from scratch_class.
4340 if (the_class->get_cached_class_file() != nullptr) {
4341 os::free(the_class->get_cached_class_file());
4342 }
4343 the_class->set_cached_class_file(scratch_class->get_cached_class_file());
4344 }
4345
4346 // NULL out in scratch class to not delete twice. The class to be redefined
4347 // always owns these bytes.
4348 scratch_class->set_cached_class_file(NULL);
4349
4350 // Replace inner_classes
4351 Array<u2>* old_inner_classes = the_class->inner_classes();
4352 the_class->set_inner_classes(scratch_class->inner_classes());
4353 scratch_class->set_inner_classes(old_inner_classes);
4354
4355 // Initialize the vtable and interface table after
4356 // methods have been rewritten
4357 // no exception should happen here since we explicitly
4358 // do not check loader constraints.
4359 // compare_and_normalize_class_versions has already checked:
4360 // - classloaders unchanged, signatures unchanged
4361 // - all instanceKlasses for redefined classes reused & contents updated
4362 the_class->vtable().initialize_vtable();
4363 the_class->itable().initialize_itable();
4364
4365 // Leave arrays of jmethodIDs and itable index cache unchanged
4366
4367 // Copy the "source debug extension" attribute from new class version
4368 the_class->set_source_debug_extension(
4369 scratch_class->source_debug_extension(),
4370 scratch_class->source_debug_extension() == NULL ? 0 :
4371 (int)strlen(scratch_class->source_debug_extension()));
4372
4373 // Use of javac -g could be different in the old and the new
4374 if (scratch_class->access_flags().has_localvariable_table() !=
4375 the_class->access_flags().has_localvariable_table()) {
4376
4377 AccessFlags flags = the_class->access_flags();
4378 if (scratch_class->access_flags().has_localvariable_table()) {
4379 flags.set_has_localvariable_table();
4380 } else {
4381 flags.clear_has_localvariable_table();
4382 }
4383 the_class->set_access_flags(flags);
4384 }
4385
4386 swap_annotations(the_class, scratch_class);
4387
4388 // Replace minor version number of class file
4389 u2 old_minor_version = the_class->constants()->minor_version();
4390 the_class->constants()->set_minor_version(scratch_class->constants()->minor_version());
4391 scratch_class->constants()->set_minor_version(old_minor_version);
4392
4393 // Replace major version number of class file
4394 u2 old_major_version = the_class->constants()->major_version();
4395 the_class->constants()->set_major_version(scratch_class->constants()->major_version());
4396 scratch_class->constants()->set_major_version(old_major_version);
4397
4398 // Replace CP indexes for class and name+type of enclosing method
4399 u2 old_class_idx = the_class->enclosing_method_class_index();
4400 u2 old_method_idx = the_class->enclosing_method_method_index();
4401 the_class->set_enclosing_method_indices(
4402 scratch_class->enclosing_method_class_index(),
4403 scratch_class->enclosing_method_method_index());
4404 scratch_class->set_enclosing_method_indices(old_class_idx, old_method_idx);
4405
4406 the_class->set_has_been_redefined();
4407
4408 // Scratch class is unloaded but still needs cleaning, and skipping for CDS.
4409 scratch_class->set_is_scratch_class();
4410
4411 // keep track of previous versions of this class
4412 the_class->add_previous_version(scratch_class, emcp_method_count);
4413
4414 _timer_rsc_phase1.stop();
4415 if (log_is_enabled(Info, redefine, class, timer)) {
4416 _timer_rsc_phase2.start();
4417 }
4418
4419 if (the_class->oop_map_cache() != NULL) {
4420 // Flush references to any obsolete methods from the oop map cache
4421 // so that obsolete methods are not pinned.
4422 the_class->oop_map_cache()->flush_obsolete_entries();
4423 }
4424
4425 increment_class_counter(the_class);
4426
4427 if (EventClassRedefinition::is_enabled()) {
4428 EventClassRedefinition event;
4429 event.set_classModificationCount(java_lang_Class::classRedefinedCount(the_class->java_mirror()));
4430 event.set_redefinedClass(the_class);
4431 event.set_redefinitionId(_id);
4432 event.commit();
4433 }
4434
4435 {
4436 ResourceMark rm(current);
4437 // increment the classRedefinedCount field in the_class and in any
4438 // direct and indirect subclasses of the_class
4439 log_info(redefine, class, load)
4440 ("redefined name=%s, count=%d (avail_mem=" UINT64_FORMAT "K)",
4441 the_class->external_name(), java_lang_Class::classRedefinedCount(the_class->java_mirror()), os::available_memory() >> 10);
4442 Events::log_redefinition(current, "redefined class name=%s, count=%d",
4443 the_class->external_name(),
4444 java_lang_Class::classRedefinedCount(the_class->java_mirror()));
4445
4446 }
4447 _timer_rsc_phase2.stop();
4448
4449 } // end redefine_single_class()
4450
4451
4452 // Increment the classRedefinedCount field in the specific InstanceKlass
4453 // and in all direct and indirect subclasses.
4454 void VM_RedefineClasses::increment_class_counter(InstanceKlass* ik) {
4455 for (ClassHierarchyIterator iter(ik); !iter.done(); iter.next()) {
4456 // Only update instanceKlasses
4457 Klass* sub = iter.klass();
4458 if (sub->is_instance_klass()) {
4459 oop class_mirror = InstanceKlass::cast(sub)->java_mirror();
4460 Klass* class_oop = java_lang_Class::as_Klass(class_mirror);
4461 int new_count = java_lang_Class::classRedefinedCount(class_mirror) + 1;
4462 java_lang_Class::set_classRedefinedCount(class_mirror, new_count);
4463
4464 if (class_oop != _the_class) {
4465 // _the_class count is printed at end of redefine_single_class()
4466 log_debug(redefine, class, subclass)("updated count in subclass=%s to %d", ik->external_name(), new_count);
4467 }
4468 }
4469 }
4470 }
4471
4472 void VM_RedefineClasses::CheckClass::do_klass(Klass* k) {
4473 bool no_old_methods = true; // be optimistic
4474
4475 // Both array and instance classes have vtables.
4476 // a vtable should never contain old or obsolete methods
4477 ResourceMark rm(_thread);
4478 if (k->vtable_length() > 0 &&
4479 !k->vtable().check_no_old_or_obsolete_entries()) {
4480 if (log_is_enabled(Trace, redefine, class, obsolete, metadata)) {
4481 log_trace(redefine, class, obsolete, metadata)
4482 ("klassVtable::check_no_old_or_obsolete_entries failure -- OLD or OBSOLETE method found -- class: %s",
4483 k->signature_name());
4484 k->vtable().dump_vtable();
4485 }
4486 no_old_methods = false;
4487 }
4488
4489 if (k->is_instance_klass()) {
4490 HandleMark hm(_thread);
4491 InstanceKlass *ik = InstanceKlass::cast(k);
4492
4493 // an itable should never contain old or obsolete methods
4494 if (ik->itable_length() > 0 &&
4495 !ik->itable().check_no_old_or_obsolete_entries()) {
4496 if (log_is_enabled(Trace, redefine, class, obsolete, metadata)) {
4497 log_trace(redefine, class, obsolete, metadata)
4498 ("klassItable::check_no_old_or_obsolete_entries failure -- OLD or OBSOLETE method found -- class: %s",
4499 ik->signature_name());
4500 ik->itable().dump_itable();
4501 }
4502 no_old_methods = false;
4503 }
4504
4505 // the constant pool cache should never contain non-deleted old or obsolete methods
4506 if (ik->constants() != NULL &&
4507 ik->constants()->cache() != NULL &&
4508 !ik->constants()->cache()->check_no_old_or_obsolete_entries()) {
4509 if (log_is_enabled(Trace, redefine, class, obsolete, metadata)) {
4510 log_trace(redefine, class, obsolete, metadata)
4511 ("cp-cache::check_no_old_or_obsolete_entries failure -- OLD or OBSOLETE method found -- class: %s",
4512 ik->signature_name());
4513 ik->constants()->cache()->dump_cache();
4514 }
4515 no_old_methods = false;
4516 }
4517 }
4518
4519 // print and fail guarantee if old methods are found.
4520 if (!no_old_methods) {
4521 if (log_is_enabled(Trace, redefine, class, obsolete, metadata)) {
4522 dump_methods();
4523 } else {
4524 log_trace(redefine, class)("Use the '-Xlog:redefine+class*:' option "
4525 "to see more info about the following guarantee() failure.");
4526 }
4527 guarantee(false, "OLD and/or OBSOLETE method(s) found");
4528 }
4529 }
4530
4531 u8 VM_RedefineClasses::next_id() {
4532 while (true) {
4533 u8 id = _id_counter;
4534 u8 next_id = id + 1;
4535 u8 result = Atomic::cmpxchg(&_id_counter, id, next_id);
4536 if (result == id) {
4537 return next_id;
4538 }
4539 }
4540 }
4541
4542 void VM_RedefineClasses::dump_methods() {
4543 int j;
4544 log_trace(redefine, class, dump)("_old_methods --");
4545 for (j = 0; j < _old_methods->length(); ++j) {
4546 LogStreamHandle(Trace, redefine, class, dump) log_stream;
4547 Method* m = _old_methods->at(j);
4548 log_stream.print("%4d (%5d) ", j, m->vtable_index());
4549 m->access_flags().print_on(&log_stream);
4550 log_stream.print(" -- ");
4551 m->print_name(&log_stream);
4552 log_stream.cr();
4553 }
4554 log_trace(redefine, class, dump)("_new_methods --");
4555 for (j = 0; j < _new_methods->length(); ++j) {
4556 LogStreamHandle(Trace, redefine, class, dump) log_stream;
4557 Method* m = _new_methods->at(j);
4558 log_stream.print("%4d (%5d) ", j, m->vtable_index());
4559 m->access_flags().print_on(&log_stream);
4560 log_stream.print(" -- ");
4561 m->print_name(&log_stream);
4562 log_stream.cr();
4563 }
4564 log_trace(redefine, class, dump)("_matching_methods --");
4565 for (j = 0; j < _matching_methods_length; ++j) {
4566 LogStreamHandle(Trace, redefine, class, dump) log_stream;
4567 Method* m = _matching_old_methods[j];
4568 log_stream.print("%4d (%5d) ", j, m->vtable_index());
4569 m->access_flags().print_on(&log_stream);
4570 log_stream.print(" -- ");
4571 m->print_name();
4572 log_stream.cr();
4573
4574 m = _matching_new_methods[j];
4575 log_stream.print(" (%5d) ", m->vtable_index());
4576 m->access_flags().print_on(&log_stream);
4577 log_stream.cr();
4578 }
4579 log_trace(redefine, class, dump)("_deleted_methods --");
4580 for (j = 0; j < _deleted_methods_length; ++j) {
4581 LogStreamHandle(Trace, redefine, class, dump) log_stream;
4582 Method* m = _deleted_methods[j];
4583 log_stream.print("%4d (%5d) ", j, m->vtable_index());
4584 m->access_flags().print_on(&log_stream);
4585 log_stream.print(" -- ");
4586 m->print_name(&log_stream);
4587 log_stream.cr();
4588 }
4589 log_trace(redefine, class, dump)("_added_methods --");
4590 for (j = 0; j < _added_methods_length; ++j) {
4591 LogStreamHandle(Trace, redefine, class, dump) log_stream;
4592 Method* m = _added_methods[j];
4593 log_stream.print("%4d (%5d) ", j, m->vtable_index());
4594 m->access_flags().print_on(&log_stream);
4595 log_stream.print(" -- ");
4596 m->print_name(&log_stream);
4597 log_stream.cr();
4598 }
4599 }
4600
4601 void VM_RedefineClasses::print_on_error(outputStream* st) const {
4602 VM_Operation::print_on_error(st);
4603 if (_the_class != NULL) {
4604 ResourceMark rm;
4605 st->print_cr(", redefining class %s", _the_class->external_name());
4606 }
4607 }