1 /*
2 * Copyright (c) 2003, 2021, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
24
25 #include "precompiled.hpp"
26 #include "cds/metaspaceShared.hpp"
27 #include "classfile/classFileStream.hpp"
28 #include "classfile/classLoaderDataGraph.hpp"
29 #include "classfile/classLoadInfo.hpp"
30 #include "classfile/javaClasses.inline.hpp"
31 #include "classfile/metadataOnStackMark.hpp"
32 #include "classfile/symbolTable.hpp"
33 #include "classfile/klassFactory.hpp"
34 #include "classfile/verifier.hpp"
35 #include "classfile/vmClasses.hpp"
36 #include "classfile/vmSymbols.hpp"
37 #include "code/codeCache.hpp"
38 #include "compiler/compileBroker.hpp"
39 #include "interpreter/oopMapCache.hpp"
40 #include "interpreter/rewriter.hpp"
41 #include "jfr/jfrEvents.hpp"
42 #include "logging/logStream.hpp"
43 #include "memory/metadataFactory.hpp"
44 #include "memory/resourceArea.hpp"
45 #include "memory/universe.hpp"
46 #include "oops/annotations.hpp"
47 #include "oops/constantPool.hpp"
48 #include "oops/fieldStreams.inline.hpp"
49 #include "oops/klass.inline.hpp"
50 #include "oops/klassVtable.hpp"
51 #include "oops/oop.inline.hpp"
52 #include "oops/recordComponent.hpp"
53 #include "prims/jvmtiImpl.hpp"
54 #include "prims/jvmtiRedefineClasses.hpp"
55 #include "prims/jvmtiThreadState.inline.hpp"
56 #include "prims/resolvedMethodTable.hpp"
57 #include "prims/methodComparator.hpp"
58 #include "runtime/atomic.hpp"
59 #include "runtime/deoptimization.hpp"
60 #include "runtime/handles.inline.hpp"
61 #include "runtime/jniHandles.inline.hpp"
62 #include "runtime/relocator.hpp"
63 #include "runtime/safepointVerifiers.hpp"
64 #include "utilities/bitMap.inline.hpp"
65 #include "utilities/events.hpp"
66
67 Array<Method*>* VM_RedefineClasses::_old_methods = NULL;
68 Array<Method*>* VM_RedefineClasses::_new_methods = NULL;
69 Method** VM_RedefineClasses::_matching_old_methods = NULL;
70 Method** VM_RedefineClasses::_matching_new_methods = NULL;
71 Method** VM_RedefineClasses::_deleted_methods = NULL;
72 Method** VM_RedefineClasses::_added_methods = NULL;
73 int VM_RedefineClasses::_matching_methods_length = 0;
74 int VM_RedefineClasses::_deleted_methods_length = 0;
75 int VM_RedefineClasses::_added_methods_length = 0;
76
77 // This flag is global as the constructor does not reset it:
78 bool VM_RedefineClasses::_has_redefined_Object = false;
79 u8 VM_RedefineClasses::_id_counter = 0;
80
81 VM_RedefineClasses::VM_RedefineClasses(jint class_count,
82 const jvmtiClassDefinition *class_defs,
83 JvmtiClassLoadKind class_load_kind) {
84 _class_count = class_count;
85 _class_defs = class_defs;
86 _class_load_kind = class_load_kind;
87 _any_class_has_resolved_methods = false;
88 _res = JVMTI_ERROR_NONE;
89 _the_class = NULL;
90 _id = next_id();
91 }
92
93 static inline InstanceKlass* get_ik(jclass def) {
94 oop mirror = JNIHandles::resolve_non_null(def);
95 return InstanceKlass::cast(java_lang_Class::as_Klass(mirror));
96 }
97
98 // If any of the classes are being redefined, wait
99 // Parallel constant pool merging leads to indeterminate constant pools.
100 void VM_RedefineClasses::lock_classes() {
101 JvmtiThreadState *state = JvmtiThreadState::state_for(JavaThread::current());
102 GrowableArray<Klass*>* redef_classes = state->get_classes_being_redefined();
103
104 MonitorLocker ml(RedefineClasses_lock);
105
106 if (redef_classes == NULL) {
107 redef_classes = new(ResourceObj::C_HEAP, mtClass) GrowableArray<Klass*>(1, mtClass);
108 state->set_classes_being_redefined(redef_classes);
109 }
110
111 bool has_redefined;
112 do {
113 has_redefined = false;
114 // Go through classes each time until none are being redefined. Skip
115 // the ones that are being redefined by this thread currently. Class file
116 // load hook event may trigger new class redefine when we are redefining
117 // a class (after lock_classes()).
118 for (int i = 0; i < _class_count; i++) {
119 InstanceKlass* ik = get_ik(_class_defs[i].klass);
120 // Check if we are currently redefining the class in this thread already.
121 if (redef_classes->contains(ik)) {
122 assert(ik->is_being_redefined(), "sanity");
123 } else {
124 if (ik->is_being_redefined()) {
125 ml.wait();
126 has_redefined = true;
127 break; // for loop
128 }
129 }
130 }
131 } while (has_redefined);
132
133 for (int i = 0; i < _class_count; i++) {
134 InstanceKlass* ik = get_ik(_class_defs[i].klass);
135 redef_classes->push(ik); // Add to the _classes_being_redefined list
136 ik->set_is_being_redefined(true);
137 }
138 ml.notify_all();
139 }
140
141 void VM_RedefineClasses::unlock_classes() {
142 JvmtiThreadState *state = JvmtiThreadState::state_for(JavaThread::current());
143 GrowableArray<Klass*>* redef_classes = state->get_classes_being_redefined();
144 assert(redef_classes != NULL, "_classes_being_redefined is not allocated");
145
146 MonitorLocker ml(RedefineClasses_lock);
147
148 for (int i = _class_count - 1; i >= 0; i--) {
149 InstanceKlass* def_ik = get_ik(_class_defs[i].klass);
150 if (redef_classes->length() > 0) {
151 // Remove the class from _classes_being_redefined list
152 Klass* k = redef_classes->pop();
153 assert(def_ik == k, "unlocking wrong class");
154 }
155 assert(def_ik->is_being_redefined(),
156 "should be being redefined to get here");
157
158 // Unlock after we finish all redefines for this class within
159 // the thread. Same class can be pushed to the list multiple
160 // times (not more than once by each recursive redefinition).
161 if (!redef_classes->contains(def_ik)) {
162 def_ik->set_is_being_redefined(false);
163 }
164 }
165 ml.notify_all();
166 }
167
168 bool VM_RedefineClasses::doit_prologue() {
169 if (_class_count == 0) {
170 _res = JVMTI_ERROR_NONE;
171 return false;
172 }
173 if (_class_defs == NULL) {
174 _res = JVMTI_ERROR_NULL_POINTER;
175 return false;
176 }
177
178 for (int i = 0; i < _class_count; i++) {
179 if (_class_defs[i].klass == NULL) {
180 _res = JVMTI_ERROR_INVALID_CLASS;
181 return false;
182 }
183 if (_class_defs[i].class_byte_count == 0) {
184 _res = JVMTI_ERROR_INVALID_CLASS_FORMAT;
185 return false;
186 }
187 if (_class_defs[i].class_bytes == NULL) {
188 _res = JVMTI_ERROR_NULL_POINTER;
189 return false;
190 }
191
192 oop mirror = JNIHandles::resolve_non_null(_class_defs[i].klass);
193 // classes for primitives, arrays, and hidden classes
194 // cannot be redefined.
195 if (!is_modifiable_class(mirror)) {
196 _res = JVMTI_ERROR_UNMODIFIABLE_CLASS;
197 return false;
198 }
199 }
200
201 // Start timer after all the sanity checks; not quite accurate, but
202 // better than adding a bunch of stop() calls.
203 if (log_is_enabled(Info, redefine, class, timer)) {
204 _timer_vm_op_prologue.start();
205 }
206
207 lock_classes();
208 // We first load new class versions in the prologue, because somewhere down the
209 // call chain it is required that the current thread is a Java thread.
210 _res = load_new_class_versions();
211 if (_res != JVMTI_ERROR_NONE) {
212 // free any successfully created classes, since none are redefined
213 for (int i = 0; i < _class_count; i++) {
214 if (_scratch_classes[i] != NULL) {
215 ClassLoaderData* cld = _scratch_classes[i]->class_loader_data();
216 // Free the memory for this class at class unloading time. Not before
217 // because CMS might think this is still live.
218 InstanceKlass* ik = get_ik(_class_defs[i].klass);
219 if (ik->get_cached_class_file() == _scratch_classes[i]->get_cached_class_file()) {
220 // Don't double-free cached_class_file copied from the original class if error.
221 _scratch_classes[i]->set_cached_class_file(NULL);
222 }
223 cld->add_to_deallocate_list(InstanceKlass::cast(_scratch_classes[i]));
224 }
225 }
226 // Free os::malloc allocated memory in load_new_class_version.
227 os::free(_scratch_classes);
228 _timer_vm_op_prologue.stop();
229 unlock_classes();
230 return false;
231 }
232
233 _timer_vm_op_prologue.stop();
234 return true;
235 }
236
237 void VM_RedefineClasses::doit() {
238 Thread* current = Thread::current();
239
240 #if INCLUDE_CDS
241 if (UseSharedSpaces) {
242 // Sharing is enabled so we remap the shared readonly space to
243 // shared readwrite, private just in case we need to redefine
244 // a shared class. We do the remap during the doit() phase of
245 // the safepoint to be safer.
246 if (!MetaspaceShared::remap_shared_readonly_as_readwrite()) {
247 log_info(redefine, class, load)("failed to remap shared readonly space to readwrite, private");
248 _res = JVMTI_ERROR_INTERNAL;
249 return;
250 }
251 }
252 #endif
253
254 // Mark methods seen on stack and everywhere else so old methods are not
255 // cleaned up if they're on the stack.
256 MetadataOnStackMark md_on_stack(/*walk_all_metadata*/true, /*redefinition_walk*/true);
257 HandleMark hm(current); // make sure any handles created are deleted
258 // before the stack walk again.
259
260 for (int i = 0; i < _class_count; i++) {
261 redefine_single_class(current, _class_defs[i].klass, _scratch_classes[i]);
262 }
263
264 // Flush all compiled code that depends on the classes redefined.
265 flush_dependent_code();
266
267 // Adjust constantpool caches and vtables for all classes
268 // that reference methods of the evolved classes.
269 // Have to do this after all classes are redefined and all methods that
270 // are redefined are marked as old.
271 AdjustAndCleanMetadata adjust_and_clean_metadata(current);
272 ClassLoaderDataGraph::classes_do(&adjust_and_clean_metadata);
273
274 // JSR-292 support
275 if (_any_class_has_resolved_methods) {
276 bool trace_name_printed = false;
277 ResolvedMethodTable::adjust_method_entries(&trace_name_printed);
278 }
279
280 // Increment flag indicating that some invariants are no longer true.
281 // See jvmtiExport.hpp for detailed explanation.
282 JvmtiExport::increment_redefinition_count();
283
284 // check_class() is optionally called for product bits, but is
285 // always called for non-product bits.
286 #ifdef PRODUCT
287 if (log_is_enabled(Trace, redefine, class, obsolete, metadata)) {
288 #endif
289 log_trace(redefine, class, obsolete, metadata)("calling check_class");
290 CheckClass check_class(current);
291 ClassLoaderDataGraph::classes_do(&check_class);
292 #ifdef PRODUCT
293 }
294 #endif
295
296 // Clean up any metadata now unreferenced while MetadataOnStackMark is set.
297 ClassLoaderDataGraph::clean_deallocate_lists(false);
298 }
299
300 void VM_RedefineClasses::doit_epilogue() {
301 unlock_classes();
302
303 // Free os::malloc allocated memory.
304 os::free(_scratch_classes);
305
306 // Reset the_class to null for error printing.
307 _the_class = NULL;
308
309 if (log_is_enabled(Info, redefine, class, timer)) {
310 // Used to have separate timers for "doit" and "all", but the timer
311 // overhead skewed the measurements.
312 julong doit_time = _timer_rsc_phase1.milliseconds() +
313 _timer_rsc_phase2.milliseconds();
314 julong all_time = _timer_vm_op_prologue.milliseconds() + doit_time;
315
316 log_info(redefine, class, timer)
317 ("vm_op: all=" JULONG_FORMAT " prologue=" JULONG_FORMAT " doit=" JULONG_FORMAT,
318 all_time, (julong)_timer_vm_op_prologue.milliseconds(), doit_time);
319 log_info(redefine, class, timer)
320 ("redefine_single_class: phase1=" JULONG_FORMAT " phase2=" JULONG_FORMAT,
321 (julong)_timer_rsc_phase1.milliseconds(), (julong)_timer_rsc_phase2.milliseconds());
322 }
323 }
324
325 bool VM_RedefineClasses::is_modifiable_class(oop klass_mirror) {
326 // classes for primitives cannot be redefined
327 if (java_lang_Class::is_primitive(klass_mirror)) {
328 return false;
329 }
330 Klass* k = java_lang_Class::as_Klass(klass_mirror);
331 // classes for arrays cannot be redefined
332 if (k == NULL || !k->is_instance_klass()) {
333 return false;
334 }
335
336 // Cannot redefine or retransform a hidden class.
337 if (InstanceKlass::cast(k)->is_hidden()) {
338 return false;
339 }
340 return true;
341 }
342
343 // Append the current entry at scratch_i in scratch_cp to *merge_cp_p
344 // where the end of *merge_cp_p is specified by *merge_cp_length_p. For
345 // direct CP entries, there is just the current entry to append. For
346 // indirect and double-indirect CP entries, there are zero or more
347 // referenced CP entries along with the current entry to append.
348 // Indirect and double-indirect CP entries are handled by recursive
349 // calls to append_entry() as needed. The referenced CP entries are
350 // always appended to *merge_cp_p before the referee CP entry. These
351 // referenced CP entries may already exist in *merge_cp_p in which case
352 // there is nothing extra to append and only the current entry is
353 // appended.
354 void VM_RedefineClasses::append_entry(const constantPoolHandle& scratch_cp,
355 int scratch_i, constantPoolHandle *merge_cp_p, int *merge_cp_length_p) {
356
357 // append is different depending on entry tag type
358 switch (scratch_cp->tag_at(scratch_i).value()) {
359
360 // The old verifier is implemented outside the VM. It loads classes,
361 // but does not resolve constant pool entries directly so we never
362 // see Class entries here with the old verifier. Similarly the old
363 // verifier does not like Class entries in the input constant pool.
364 // The split-verifier is implemented in the VM so it can optionally
365 // and directly resolve constant pool entries to load classes. The
366 // split-verifier can accept either Class entries or UnresolvedClass
367 // entries in the input constant pool. We revert the appended copy
368 // back to UnresolvedClass so that either verifier will be happy
369 // with the constant pool entry.
370 //
371 // this is an indirect CP entry so it needs special handling
372 case JVM_CONSTANT_Class:
373 case JVM_CONSTANT_UnresolvedClass:
374 {
375 int name_i = scratch_cp->klass_name_index_at(scratch_i);
376 int new_name_i = find_or_append_indirect_entry(scratch_cp, name_i, merge_cp_p,
377 merge_cp_length_p);
378
379 if (new_name_i != name_i) {
380 log_trace(redefine, class, constantpool)
381 ("Class entry@%d name_index change: %d to %d",
382 *merge_cp_length_p, name_i, new_name_i);
383 }
384
385 (*merge_cp_p)->temp_unresolved_klass_at_put(*merge_cp_length_p, new_name_i);
386 if (scratch_i != *merge_cp_length_p) {
387 // The new entry in *merge_cp_p is at a different index than
388 // the new entry in scratch_cp so we need to map the index values.
389 map_index(scratch_cp, scratch_i, *merge_cp_length_p);
390 }
391 (*merge_cp_length_p)++;
392 } break;
393
394 // these are direct CP entries so they can be directly appended,
395 // but double and long take two constant pool entries
396 case JVM_CONSTANT_Double: // fall through
397 case JVM_CONSTANT_Long:
398 {
399 ConstantPool::copy_entry_to(scratch_cp, scratch_i, *merge_cp_p, *merge_cp_length_p);
400
401 if (scratch_i != *merge_cp_length_p) {
402 // The new entry in *merge_cp_p is at a different index than
403 // the new entry in scratch_cp so we need to map the index values.
404 map_index(scratch_cp, scratch_i, *merge_cp_length_p);
405 }
406 (*merge_cp_length_p) += 2;
407 } break;
408
409 // these are direct CP entries so they can be directly appended
410 case JVM_CONSTANT_Float: // fall through
411 case JVM_CONSTANT_Integer: // fall through
412 case JVM_CONSTANT_Utf8: // fall through
413
414 // This was an indirect CP entry, but it has been changed into
415 // Symbol*s so this entry can be directly appended.
416 case JVM_CONSTANT_String: // fall through
417 {
418 ConstantPool::copy_entry_to(scratch_cp, scratch_i, *merge_cp_p, *merge_cp_length_p);
419
420 if (scratch_i != *merge_cp_length_p) {
421 // The new entry in *merge_cp_p is at a different index than
422 // the new entry in scratch_cp so we need to map the index values.
423 map_index(scratch_cp, scratch_i, *merge_cp_length_p);
424 }
425 (*merge_cp_length_p)++;
426 } break;
427
428 // this is an indirect CP entry so it needs special handling
429 case JVM_CONSTANT_NameAndType:
430 {
431 int name_ref_i = scratch_cp->name_ref_index_at(scratch_i);
432 int new_name_ref_i = find_or_append_indirect_entry(scratch_cp, name_ref_i, merge_cp_p,
433 merge_cp_length_p);
434
435 int signature_ref_i = scratch_cp->signature_ref_index_at(scratch_i);
436 int new_signature_ref_i = find_or_append_indirect_entry(scratch_cp, signature_ref_i,
437 merge_cp_p, merge_cp_length_p);
438
439 // If the referenced entries already exist in *merge_cp_p, then
440 // both new_name_ref_i and new_signature_ref_i will both be 0.
441 // In that case, all we are appending is the current entry.
442 if (new_name_ref_i != name_ref_i) {
443 log_trace(redefine, class, constantpool)
444 ("NameAndType entry@%d name_ref_index change: %d to %d",
445 *merge_cp_length_p, name_ref_i, new_name_ref_i);
446 }
447 if (new_signature_ref_i != signature_ref_i) {
448 log_trace(redefine, class, constantpool)
449 ("NameAndType entry@%d signature_ref_index change: %d to %d",
450 *merge_cp_length_p, signature_ref_i, new_signature_ref_i);
451 }
452
453 (*merge_cp_p)->name_and_type_at_put(*merge_cp_length_p,
454 new_name_ref_i, new_signature_ref_i);
455 if (scratch_i != *merge_cp_length_p) {
456 // The new entry in *merge_cp_p is at a different index than
457 // the new entry in scratch_cp so we need to map the index values.
458 map_index(scratch_cp, scratch_i, *merge_cp_length_p);
459 }
460 (*merge_cp_length_p)++;
461 } break;
462
463 // this is a double-indirect CP entry so it needs special handling
464 case JVM_CONSTANT_Fieldref: // fall through
465 case JVM_CONSTANT_InterfaceMethodref: // fall through
466 case JVM_CONSTANT_Methodref:
467 {
468 int klass_ref_i = scratch_cp->uncached_klass_ref_index_at(scratch_i);
469 int new_klass_ref_i = find_or_append_indirect_entry(scratch_cp, klass_ref_i,
470 merge_cp_p, merge_cp_length_p);
471
472 int name_and_type_ref_i = scratch_cp->uncached_name_and_type_ref_index_at(scratch_i);
473 int new_name_and_type_ref_i = find_or_append_indirect_entry(scratch_cp, name_and_type_ref_i,
474 merge_cp_p, merge_cp_length_p);
475
476 const char *entry_name = NULL;
477 switch (scratch_cp->tag_at(scratch_i).value()) {
478 case JVM_CONSTANT_Fieldref:
479 entry_name = "Fieldref";
480 (*merge_cp_p)->field_at_put(*merge_cp_length_p, new_klass_ref_i,
481 new_name_and_type_ref_i);
482 break;
483 case JVM_CONSTANT_InterfaceMethodref:
484 entry_name = "IFMethodref";
485 (*merge_cp_p)->interface_method_at_put(*merge_cp_length_p,
486 new_klass_ref_i, new_name_and_type_ref_i);
487 break;
488 case JVM_CONSTANT_Methodref:
489 entry_name = "Methodref";
490 (*merge_cp_p)->method_at_put(*merge_cp_length_p, new_klass_ref_i,
491 new_name_and_type_ref_i);
492 break;
493 default:
494 guarantee(false, "bad switch");
495 break;
496 }
497
498 if (klass_ref_i != new_klass_ref_i) {
499 log_trace(redefine, class, constantpool)
500 ("%s entry@%d class_index changed: %d to %d", entry_name, *merge_cp_length_p, klass_ref_i, new_klass_ref_i);
501 }
502 if (name_and_type_ref_i != new_name_and_type_ref_i) {
503 log_trace(redefine, class, constantpool)
504 ("%s entry@%d name_and_type_index changed: %d to %d",
505 entry_name, *merge_cp_length_p, name_and_type_ref_i, new_name_and_type_ref_i);
506 }
507
508 if (scratch_i != *merge_cp_length_p) {
509 // The new entry in *merge_cp_p is at a different index than
510 // the new entry in scratch_cp so we need to map the index values.
511 map_index(scratch_cp, scratch_i, *merge_cp_length_p);
512 }
513 (*merge_cp_length_p)++;
514 } break;
515
516 // this is an indirect CP entry so it needs special handling
517 case JVM_CONSTANT_MethodType:
518 {
519 int ref_i = scratch_cp->method_type_index_at(scratch_i);
520 int new_ref_i = find_or_append_indirect_entry(scratch_cp, ref_i, merge_cp_p,
521 merge_cp_length_p);
522 if (new_ref_i != ref_i) {
523 log_trace(redefine, class, constantpool)
524 ("MethodType entry@%d ref_index change: %d to %d", *merge_cp_length_p, ref_i, new_ref_i);
525 }
526 (*merge_cp_p)->method_type_index_at_put(*merge_cp_length_p, new_ref_i);
527 if (scratch_i != *merge_cp_length_p) {
528 // The new entry in *merge_cp_p is at a different index than
529 // the new entry in scratch_cp so we need to map the index values.
530 map_index(scratch_cp, scratch_i, *merge_cp_length_p);
531 }
532 (*merge_cp_length_p)++;
533 } break;
534
535 // this is an indirect CP entry so it needs special handling
536 case JVM_CONSTANT_MethodHandle:
537 {
538 int ref_kind = scratch_cp->method_handle_ref_kind_at(scratch_i);
539 int ref_i = scratch_cp->method_handle_index_at(scratch_i);
540 int new_ref_i = find_or_append_indirect_entry(scratch_cp, ref_i, merge_cp_p,
541 merge_cp_length_p);
542 if (new_ref_i != ref_i) {
543 log_trace(redefine, class, constantpool)
544 ("MethodHandle entry@%d ref_index change: %d to %d", *merge_cp_length_p, ref_i, new_ref_i);
545 }
546 (*merge_cp_p)->method_handle_index_at_put(*merge_cp_length_p, ref_kind, new_ref_i);
547 if (scratch_i != *merge_cp_length_p) {
548 // The new entry in *merge_cp_p is at a different index than
549 // the new entry in scratch_cp so we need to map the index values.
550 map_index(scratch_cp, scratch_i, *merge_cp_length_p);
551 }
552 (*merge_cp_length_p)++;
553 } break;
554
555 // this is an indirect CP entry so it needs special handling
556 case JVM_CONSTANT_Dynamic: // fall through
557 case JVM_CONSTANT_InvokeDynamic:
558 {
559 // Index of the bootstrap specifier in the operands array
560 int old_bs_i = scratch_cp->bootstrap_methods_attribute_index(scratch_i);
561 int new_bs_i = find_or_append_operand(scratch_cp, old_bs_i, merge_cp_p,
562 merge_cp_length_p);
563 // The bootstrap method NameAndType_info index
564 int old_ref_i = scratch_cp->bootstrap_name_and_type_ref_index_at(scratch_i);
565 int new_ref_i = find_or_append_indirect_entry(scratch_cp, old_ref_i, merge_cp_p,
566 merge_cp_length_p);
567 if (new_bs_i != old_bs_i) {
568 log_trace(redefine, class, constantpool)
569 ("Dynamic entry@%d bootstrap_method_attr_index change: %d to %d",
570 *merge_cp_length_p, old_bs_i, new_bs_i);
571 }
572 if (new_ref_i != old_ref_i) {
573 log_trace(redefine, class, constantpool)
574 ("Dynamic entry@%d name_and_type_index change: %d to %d", *merge_cp_length_p, old_ref_i, new_ref_i);
575 }
576
577 if (scratch_cp->tag_at(scratch_i).is_dynamic_constant())
578 (*merge_cp_p)->dynamic_constant_at_put(*merge_cp_length_p, new_bs_i, new_ref_i);
579 else
580 (*merge_cp_p)->invoke_dynamic_at_put(*merge_cp_length_p, new_bs_i, new_ref_i);
581 if (scratch_i != *merge_cp_length_p) {
582 // The new entry in *merge_cp_p is at a different index than
583 // the new entry in scratch_cp so we need to map the index values.
584 map_index(scratch_cp, scratch_i, *merge_cp_length_p);
585 }
586 (*merge_cp_length_p)++;
587 } break;
588
589 // At this stage, Class or UnresolvedClass could be in scratch_cp, but not
590 // ClassIndex
591 case JVM_CONSTANT_ClassIndex: // fall through
592
593 // Invalid is used as the tag for the second constant pool entry
594 // occupied by JVM_CONSTANT_Double or JVM_CONSTANT_Long. It should
595 // not be seen by itself.
596 case JVM_CONSTANT_Invalid: // fall through
597
598 // At this stage, String could be here, but not StringIndex
599 case JVM_CONSTANT_StringIndex: // fall through
600
601 // At this stage JVM_CONSTANT_UnresolvedClassInError should not be
602 // here
603 case JVM_CONSTANT_UnresolvedClassInError: // fall through
604
605 default:
606 {
607 // leave a breadcrumb
608 jbyte bad_value = scratch_cp->tag_at(scratch_i).value();
609 ShouldNotReachHere();
610 } break;
611 } // end switch tag value
612 } // end append_entry()
613
614
615 int VM_RedefineClasses::find_or_append_indirect_entry(const constantPoolHandle& scratch_cp,
616 int ref_i, constantPoolHandle *merge_cp_p, int *merge_cp_length_p) {
617
618 int new_ref_i = ref_i;
619 bool match = (ref_i < *merge_cp_length_p) &&
620 scratch_cp->compare_entry_to(ref_i, *merge_cp_p, ref_i);
621
622 if (!match) {
623 // forward reference in *merge_cp_p or not a direct match
624 int found_i = scratch_cp->find_matching_entry(ref_i, *merge_cp_p);
625 if (found_i != 0) {
626 guarantee(found_i != ref_i, "compare_entry_to() and find_matching_entry() do not agree");
627 // Found a matching entry somewhere else in *merge_cp_p so just need a mapping entry.
628 new_ref_i = found_i;
629 map_index(scratch_cp, ref_i, found_i);
630 } else {
631 // no match found so we have to append this entry to *merge_cp_p
632 append_entry(scratch_cp, ref_i, merge_cp_p, merge_cp_length_p);
633 // The above call to append_entry() can only append one entry
634 // so the post call query of *merge_cp_length_p is only for
635 // the sake of consistency.
636 new_ref_i = *merge_cp_length_p - 1;
637 }
638 }
639
640 return new_ref_i;
641 } // end find_or_append_indirect_entry()
642
643
644 // Append a bootstrap specifier into the merge_cp operands that is semantically equal
645 // to the scratch_cp operands bootstrap specifier passed by the old_bs_i index.
646 // Recursively append new merge_cp entries referenced by the new bootstrap specifier.
647 void VM_RedefineClasses::append_operand(const constantPoolHandle& scratch_cp, int old_bs_i,
648 constantPoolHandle *merge_cp_p, int *merge_cp_length_p) {
649
650 int old_ref_i = scratch_cp->operand_bootstrap_method_ref_index_at(old_bs_i);
651 int new_ref_i = find_or_append_indirect_entry(scratch_cp, old_ref_i, merge_cp_p,
652 merge_cp_length_p);
653 if (new_ref_i != old_ref_i) {
654 log_trace(redefine, class, constantpool)
655 ("operands entry@%d bootstrap method ref_index change: %d to %d", _operands_cur_length, old_ref_i, new_ref_i);
656 }
657
658 Array<u2>* merge_ops = (*merge_cp_p)->operands();
659 int new_bs_i = _operands_cur_length;
660 // We have _operands_cur_length == 0 when the merge_cp operands is empty yet.
661 // However, the operand_offset_at(0) was set in the extend_operands() call.
662 int new_base = (new_bs_i == 0) ? (*merge_cp_p)->operand_offset_at(0)
663 : (*merge_cp_p)->operand_next_offset_at(new_bs_i - 1);
664 int argc = scratch_cp->operand_argument_count_at(old_bs_i);
665
666 ConstantPool::operand_offset_at_put(merge_ops, _operands_cur_length, new_base);
667 merge_ops->at_put(new_base++, new_ref_i);
668 merge_ops->at_put(new_base++, argc);
669
670 for (int i = 0; i < argc; i++) {
671 int old_arg_ref_i = scratch_cp->operand_argument_index_at(old_bs_i, i);
672 int new_arg_ref_i = find_or_append_indirect_entry(scratch_cp, old_arg_ref_i, merge_cp_p,
673 merge_cp_length_p);
674 merge_ops->at_put(new_base++, new_arg_ref_i);
675 if (new_arg_ref_i != old_arg_ref_i) {
676 log_trace(redefine, class, constantpool)
677 ("operands entry@%d bootstrap method argument ref_index change: %d to %d",
678 _operands_cur_length, old_arg_ref_i, new_arg_ref_i);
679 }
680 }
681 if (old_bs_i != _operands_cur_length) {
682 // The bootstrap specifier in *merge_cp_p is at a different index than
683 // that in scratch_cp so we need to map the index values.
684 map_operand_index(old_bs_i, new_bs_i);
685 }
686 _operands_cur_length++;
687 } // end append_operand()
688
689
690 int VM_RedefineClasses::find_or_append_operand(const constantPoolHandle& scratch_cp,
691 int old_bs_i, constantPoolHandle *merge_cp_p, int *merge_cp_length_p) {
692
693 int new_bs_i = old_bs_i; // bootstrap specifier index
694 bool match = (old_bs_i < _operands_cur_length) &&
695 scratch_cp->compare_operand_to(old_bs_i, *merge_cp_p, old_bs_i);
696
697 if (!match) {
698 // forward reference in *merge_cp_p or not a direct match
699 int found_i = scratch_cp->find_matching_operand(old_bs_i, *merge_cp_p,
700 _operands_cur_length);
701 if (found_i != -1) {
702 guarantee(found_i != old_bs_i, "compare_operand_to() and find_matching_operand() disagree");
703 // found a matching operand somewhere else in *merge_cp_p so just need a mapping
704 new_bs_i = found_i;
705 map_operand_index(old_bs_i, found_i);
706 } else {
707 // no match found so we have to append this bootstrap specifier to *merge_cp_p
708 append_operand(scratch_cp, old_bs_i, merge_cp_p, merge_cp_length_p);
709 new_bs_i = _operands_cur_length - 1;
710 }
711 }
712 return new_bs_i;
713 } // end find_or_append_operand()
714
715
716 void VM_RedefineClasses::finalize_operands_merge(const constantPoolHandle& merge_cp, TRAPS) {
717 if (merge_cp->operands() == NULL) {
718 return;
719 }
720 // Shrink the merge_cp operands
721 merge_cp->shrink_operands(_operands_cur_length, CHECK);
722
723 if (log_is_enabled(Trace, redefine, class, constantpool)) {
724 // don't want to loop unless we are tracing
725 int count = 0;
726 for (int i = 1; i < _operands_index_map_p->length(); i++) {
727 int value = _operands_index_map_p->at(i);
728 if (value != -1) {
729 log_trace(redefine, class, constantpool)("operands_index_map[%d]: old=%d new=%d", count, i, value);
730 count++;
731 }
732 }
733 }
734 // Clean-up
735 _operands_index_map_p = NULL;
736 _operands_cur_length = 0;
737 _operands_index_map_count = 0;
738 } // end finalize_operands_merge()
739
740 // Symbol* comparator for qsort
741 // The caller must have an active ResourceMark.
742 static int symcmp(const void* a, const void* b) {
743 char* astr = (*(Symbol**)a)->as_C_string();
744 char* bstr = (*(Symbol**)b)->as_C_string();
745 return strcmp(astr, bstr);
746 }
747
748 // The caller must have an active ResourceMark.
749 static jvmtiError check_attribute_arrays(const char* attr_name,
750 InstanceKlass* the_class, InstanceKlass* scratch_class,
751 Array<u2>* the_array, Array<u2>* scr_array) {
752 bool the_array_exists = the_array != Universe::the_empty_short_array();
753 bool scr_array_exists = scr_array != Universe::the_empty_short_array();
754
755 int array_len = the_array->length();
756 if (the_array_exists && scr_array_exists) {
757 if (array_len != scr_array->length()) {
758 log_trace(redefine, class)
759 ("redefined class %s attribute change error: %s len=%d changed to len=%d",
760 the_class->external_name(), attr_name, array_len, scr_array->length());
761 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_CLASS_ATTRIBUTE_CHANGED;
762 }
763
764 // The order of entries in the attribute array is not specified so we
765 // have to explicitly check for the same contents. We do this by copying
766 // the referenced symbols into their own arrays, sorting them and then
767 // comparing each element pair.
768
769 Symbol** the_syms = NEW_RESOURCE_ARRAY_RETURN_NULL(Symbol*, array_len);
770 Symbol** scr_syms = NEW_RESOURCE_ARRAY_RETURN_NULL(Symbol*, array_len);
771
772 if (the_syms == NULL || scr_syms == NULL) {
773 return JVMTI_ERROR_OUT_OF_MEMORY;
774 }
775
776 for (int i = 0; i < array_len; i++) {
777 int the_cp_index = the_array->at(i);
778 int scr_cp_index = scr_array->at(i);
779 the_syms[i] = the_class->constants()->klass_name_at(the_cp_index);
780 scr_syms[i] = scratch_class->constants()->klass_name_at(scr_cp_index);
781 }
782
783 qsort(the_syms, array_len, sizeof(Symbol*), symcmp);
784 qsort(scr_syms, array_len, sizeof(Symbol*), symcmp);
785
786 for (int i = 0; i < array_len; i++) {
787 if (the_syms[i] != scr_syms[i]) {
788 log_info(redefine, class)
789 ("redefined class %s attribute change error: %s[%d]: %s changed to %s",
790 the_class->external_name(), attr_name, i,
791 the_syms[i]->as_C_string(), scr_syms[i]->as_C_string());
792 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_CLASS_ATTRIBUTE_CHANGED;
793 }
794 }
795 } else if (the_array_exists ^ scr_array_exists) {
796 const char* action_str = (the_array_exists) ? "removed" : "added";
797 log_info(redefine, class)
798 ("redefined class %s attribute change error: %s attribute %s",
799 the_class->external_name(), attr_name, action_str);
800 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_CLASS_ATTRIBUTE_CHANGED;
801 }
802 return JVMTI_ERROR_NONE;
803 }
804
805 static jvmtiError check_nest_attributes(InstanceKlass* the_class,
806 InstanceKlass* scratch_class) {
807 // Check whether the class NestHost attribute has been changed.
808 Thread* thread = Thread::current();
809 ResourceMark rm(thread);
810 u2 the_nest_host_idx = the_class->nest_host_index();
811 u2 scr_nest_host_idx = scratch_class->nest_host_index();
812
813 if (the_nest_host_idx != 0 && scr_nest_host_idx != 0) {
814 Symbol* the_sym = the_class->constants()->klass_name_at(the_nest_host_idx);
815 Symbol* scr_sym = scratch_class->constants()->klass_name_at(scr_nest_host_idx);
816 if (the_sym != scr_sym) {
817 log_info(redefine, class, nestmates)
818 ("redefined class %s attribute change error: NestHost class: %s replaced with: %s",
819 the_class->external_name(), the_sym->as_C_string(), scr_sym->as_C_string());
820 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_CLASS_ATTRIBUTE_CHANGED;
821 }
822 } else if ((the_nest_host_idx == 0) ^ (scr_nest_host_idx == 0)) {
823 const char* action_str = (the_nest_host_idx != 0) ? "removed" : "added";
824 log_info(redefine, class, nestmates)
825 ("redefined class %s attribute change error: NestHost attribute %s",
826 the_class->external_name(), action_str);
827 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_CLASS_ATTRIBUTE_CHANGED;
828 }
829
830 // Check whether the class NestMembers attribute has been changed.
831 return check_attribute_arrays("NestMembers",
832 the_class, scratch_class,
833 the_class->nest_members(),
834 scratch_class->nest_members());
835 }
836
837 // Return an error status if the class Record attribute was changed.
838 static jvmtiError check_record_attribute(InstanceKlass* the_class, InstanceKlass* scratch_class) {
839 // Get lists of record components.
840 Array<RecordComponent*>* the_record = the_class->record_components();
841 Array<RecordComponent*>* scr_record = scratch_class->record_components();
842 bool the_record_exists = the_record != NULL;
843 bool scr_record_exists = scr_record != NULL;
844
845 if (the_record_exists && scr_record_exists) {
846 int the_num_components = the_record->length();
847 int scr_num_components = scr_record->length();
848 if (the_num_components != scr_num_components) {
849 log_info(redefine, class, record)
850 ("redefined class %s attribute change error: Record num_components=%d changed to num_components=%d",
851 the_class->external_name(), the_num_components, scr_num_components);
852 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_CLASS_ATTRIBUTE_CHANGED;
853 }
854
855 // Compare each field in each record component.
856 ConstantPool* the_cp = the_class->constants();
857 ConstantPool* scr_cp = scratch_class->constants();
858 for (int x = 0; x < the_num_components; x++) {
859 RecordComponent* the_component = the_record->at(x);
860 RecordComponent* scr_component = scr_record->at(x);
861 const Symbol* const the_name = the_cp->symbol_at(the_component->name_index());
862 const Symbol* const scr_name = scr_cp->symbol_at(scr_component->name_index());
863 const Symbol* const the_descr = the_cp->symbol_at(the_component->descriptor_index());
864 const Symbol* const scr_descr = scr_cp->symbol_at(scr_component->descriptor_index());
865 if (the_name != scr_name || the_descr != scr_descr) {
866 log_info(redefine, class, record)
867 ("redefined class %s attribute change error: Record name_index, descriptor_index, and/or attributes_count changed",
868 the_class->external_name());
869 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_CLASS_ATTRIBUTE_CHANGED;
870 }
871
872 int the_gen_sig = the_component->generic_signature_index();
873 int scr_gen_sig = scr_component->generic_signature_index();
874 const Symbol* const the_gen_sig_sym = (the_gen_sig == 0 ? NULL :
875 the_cp->symbol_at(the_component->generic_signature_index()));
876 const Symbol* const scr_gen_sig_sym = (scr_gen_sig == 0 ? NULL :
877 scr_cp->symbol_at(scr_component->generic_signature_index()));
878 if (the_gen_sig_sym != scr_gen_sig_sym) {
879 log_info(redefine, class, record)
880 ("redefined class %s attribute change error: Record generic_signature attribute changed",
881 the_class->external_name());
882 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_CLASS_ATTRIBUTE_CHANGED;
883 }
884
885 // It's okay if a record component's annotations were changed.
886 }
887
888 } else if (the_record_exists ^ scr_record_exists) {
889 const char* action_str = (the_record_exists) ? "removed" : "added";
890 log_info(redefine, class, record)
891 ("redefined class %s attribute change error: Record attribute %s",
892 the_class->external_name(), action_str);
893 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_CLASS_ATTRIBUTE_CHANGED;
894 }
895
896 return JVMTI_ERROR_NONE;
897 }
898
899
900 static jvmtiError check_permitted_subclasses_attribute(InstanceKlass* the_class,
901 InstanceKlass* scratch_class) {
902 Thread* thread = Thread::current();
903 ResourceMark rm(thread);
904
905 // Check whether the class PermittedSubclasses attribute has been changed.
906 return check_attribute_arrays("PermittedSubclasses",
907 the_class, scratch_class,
908 the_class->permitted_subclasses(),
909 scratch_class->permitted_subclasses());
910 }
911
912 static bool can_add_or_delete(Method* m) {
913 // Compatibility mode
914 return (AllowRedefinitionToAddDeleteMethods &&
915 (m->is_private() && (m->is_static() || m->is_final())));
916 }
917
918 jvmtiError VM_RedefineClasses::compare_and_normalize_class_versions(
919 InstanceKlass* the_class,
920 InstanceKlass* scratch_class) {
921 int i;
922
923 // Check superclasses, or rather their names, since superclasses themselves can be
924 // requested to replace.
925 // Check for NULL superclass first since this might be java.lang.Object
926 if (the_class->super() != scratch_class->super() &&
927 (the_class->super() == NULL || scratch_class->super() == NULL ||
928 the_class->super()->name() !=
929 scratch_class->super()->name())) {
930 log_info(redefine, class, normalize)
931 ("redefined class %s superclass change error: superclass changed from %s to %s.",
932 the_class->external_name(),
933 the_class->super() == NULL ? "NULL" : the_class->super()->external_name(),
934 scratch_class->super() == NULL ? "NULL" : scratch_class->super()->external_name());
935 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_HIERARCHY_CHANGED;
936 }
937
938 // Check if the number, names and order of directly implemented interfaces are the same.
939 // I think in principle we should just check if the sets of names of directly implemented
940 // interfaces are the same, i.e. the order of declaration (which, however, if changed in the
941 // .java file, also changes in .class file) should not matter. However, comparing sets is
942 // technically a bit more difficult, and, more importantly, I am not sure at present that the
943 // order of interfaces does not matter on the implementation level, i.e. that the VM does not
944 // rely on it somewhere.
945 Array<InstanceKlass*>* k_interfaces = the_class->local_interfaces();
946 Array<InstanceKlass*>* k_new_interfaces = scratch_class->local_interfaces();
947 int n_intfs = k_interfaces->length();
948 if (n_intfs != k_new_interfaces->length()) {
949 log_info(redefine, class, normalize)
950 ("redefined class %s interfaces change error: number of implemented interfaces changed from %d to %d.",
951 the_class->external_name(), n_intfs, k_new_interfaces->length());
952 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_HIERARCHY_CHANGED;
953 }
954 for (i = 0; i < n_intfs; i++) {
955 if (k_interfaces->at(i)->name() !=
956 k_new_interfaces->at(i)->name()) {
957 log_info(redefine, class, normalize)
958 ("redefined class %s interfaces change error: interface changed from %s to %s.",
959 the_class->external_name(),
960 k_interfaces->at(i)->external_name(), k_new_interfaces->at(i)->external_name());
961 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_HIERARCHY_CHANGED;
962 }
963 }
964
965 // Check whether class is in the error init state.
966 if (the_class->is_in_error_state()) {
967 log_info(redefine, class, normalize)
968 ("redefined class %s is in error init state.", the_class->external_name());
969 // TBD #5057930: special error code is needed in 1.6
970 return JVMTI_ERROR_INVALID_CLASS;
971 }
972
973 // Check whether the nest-related attributes have been changed.
974 jvmtiError err = check_nest_attributes(the_class, scratch_class);
975 if (err != JVMTI_ERROR_NONE) {
976 return err;
977 }
978
979 // Check whether the Record attribute has been changed.
980 err = check_record_attribute(the_class, scratch_class);
981 if (err != JVMTI_ERROR_NONE) {
982 return err;
983 }
984
985 // Check whether the PermittedSubclasses attribute has been changed.
986 err = check_permitted_subclasses_attribute(the_class, scratch_class);
987 if (err != JVMTI_ERROR_NONE) {
988 return err;
989 }
990
991 // Check whether class modifiers are the same.
992 jushort old_flags = (jushort) the_class->access_flags().get_flags();
993 jushort new_flags = (jushort) scratch_class->access_flags().get_flags();
994 if (old_flags != new_flags) {
995 log_info(redefine, class, normalize)
996 ("redefined class %s modifiers change error: modifiers changed from %d to %d.",
997 the_class->external_name(), old_flags, new_flags);
998 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_CLASS_MODIFIERS_CHANGED;
999 }
1000
1001 // Check if the number, names, types and order of fields declared in these classes
1002 // are the same.
1003 JavaFieldStream old_fs(the_class);
1004 JavaFieldStream new_fs(scratch_class);
1005 for (; !old_fs.done() && !new_fs.done(); old_fs.next(), new_fs.next()) {
1006 // name and signature
1007 Symbol* name_sym1 = the_class->constants()->symbol_at(old_fs.name_index());
1008 Symbol* sig_sym1 = the_class->constants()->symbol_at(old_fs.signature_index());
1009 Symbol* name_sym2 = scratch_class->constants()->symbol_at(new_fs.name_index());
1010 Symbol* sig_sym2 = scratch_class->constants()->symbol_at(new_fs.signature_index());
1011 if (name_sym1 != name_sym2 || sig_sym1 != sig_sym2) {
1012 log_info(redefine, class, normalize)
1013 ("redefined class %s fields change error: field %s %s changed to %s %s.",
1014 the_class->external_name(),
1015 sig_sym1->as_C_string(), name_sym1->as_C_string(),
1016 sig_sym2->as_C_string(), name_sym2->as_C_string());
1017 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_SCHEMA_CHANGED;
1018 }
1019 // offset
1020 if (old_fs.offset() != new_fs.offset()) {
1021 log_info(redefine, class, normalize)
1022 ("redefined class %s field %s change error: offset changed from %d to %d.",
1023 the_class->external_name(), name_sym2->as_C_string(), old_fs.offset(), new_fs.offset());
1024 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_SCHEMA_CHANGED;
1025 }
1026 // access
1027 old_flags = old_fs.access_flags().as_short();
1028 new_flags = new_fs.access_flags().as_short();
1029 if ((old_flags ^ new_flags) & JVM_RECOGNIZED_FIELD_MODIFIERS) {
1030 log_info(redefine, class, normalize)
1031 ("redefined class %s field %s change error: modifiers changed from %d to %d.",
1032 the_class->external_name(), name_sym2->as_C_string(), old_flags, new_flags);
1033 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_SCHEMA_CHANGED;
1034 }
1035 }
1036
1037 // If both streams aren't done then we have a differing number of
1038 // fields.
1039 if (!old_fs.done() || !new_fs.done()) {
1040 const char* action = old_fs.done() ? "added" : "deleted";
1041 log_info(redefine, class, normalize)
1042 ("redefined class %s fields change error: some fields were %s.",
1043 the_class->external_name(), action);
1044 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_SCHEMA_CHANGED;
1045 }
1046
1047 // Do a parallel walk through the old and new methods. Detect
1048 // cases where they match (exist in both), have been added in
1049 // the new methods, or have been deleted (exist only in the
1050 // old methods). The class file parser places methods in order
1051 // by method name, but does not order overloaded methods by
1052 // signature. In order to determine what fate befell the methods,
1053 // this code places the overloaded new methods that have matching
1054 // old methods in the same order as the old methods and places
1055 // new overloaded methods at the end of overloaded methods of
1056 // that name. The code for this order normalization is adapted
1057 // from the algorithm used in InstanceKlass::find_method().
1058 // Since we are swapping out of order entries as we find them,
1059 // we only have to search forward through the overloaded methods.
1060 // Methods which are added and have the same name as an existing
1061 // method (but different signature) will be put at the end of
1062 // the methods with that name, and the name mismatch code will
1063 // handle them.
1064 Array<Method*>* k_old_methods(the_class->methods());
1065 Array<Method*>* k_new_methods(scratch_class->methods());
1066 int n_old_methods = k_old_methods->length();
1067 int n_new_methods = k_new_methods->length();
1068 Thread* thread = Thread::current();
1069
1070 int ni = 0;
1071 int oi = 0;
1072 while (true) {
1073 Method* k_old_method;
1074 Method* k_new_method;
1075 enum { matched, added, deleted, undetermined } method_was = undetermined;
1076
1077 if (oi >= n_old_methods) {
1078 if (ni >= n_new_methods) {
1079 break; // we've looked at everything, done
1080 }
1081 // New method at the end
1082 k_new_method = k_new_methods->at(ni);
1083 method_was = added;
1084 } else if (ni >= n_new_methods) {
1085 // Old method, at the end, is deleted
1086 k_old_method = k_old_methods->at(oi);
1087 method_was = deleted;
1088 } else {
1089 // There are more methods in both the old and new lists
1090 k_old_method = k_old_methods->at(oi);
1091 k_new_method = k_new_methods->at(ni);
1092 if (k_old_method->name() != k_new_method->name()) {
1093 // Methods are sorted by method name, so a mismatch means added
1094 // or deleted
1095 if (k_old_method->name()->fast_compare(k_new_method->name()) > 0) {
1096 method_was = added;
1097 } else {
1098 method_was = deleted;
1099 }
1100 } else if (k_old_method->signature() == k_new_method->signature()) {
1101 // Both the name and signature match
1102 method_was = matched;
1103 } else {
1104 // The name matches, but the signature doesn't, which means we have to
1105 // search forward through the new overloaded methods.
1106 int nj; // outside the loop for post-loop check
1107 for (nj = ni + 1; nj < n_new_methods; nj++) {
1108 Method* m = k_new_methods->at(nj);
1109 if (k_old_method->name() != m->name()) {
1110 // reached another method name so no more overloaded methods
1111 method_was = deleted;
1112 break;
1113 }
1114 if (k_old_method->signature() == m->signature()) {
1115 // found a match so swap the methods
1116 k_new_methods->at_put(ni, m);
1117 k_new_methods->at_put(nj, k_new_method);
1118 k_new_method = m;
1119 method_was = matched;
1120 break;
1121 }
1122 }
1123
1124 if (nj >= n_new_methods) {
1125 // reached the end without a match; so method was deleted
1126 method_was = deleted;
1127 }
1128 }
1129 }
1130
1131 switch (method_was) {
1132 case matched:
1133 // methods match, be sure modifiers do too
1134 old_flags = (jushort) k_old_method->access_flags().get_flags();
1135 new_flags = (jushort) k_new_method->access_flags().get_flags();
1136 if ((old_flags ^ new_flags) & ~(JVM_ACC_NATIVE)) {
1137 log_info(redefine, class, normalize)
1138 ("redefined class %s method %s modifiers error: modifiers changed from %d to %d",
1139 the_class->external_name(), k_old_method->name_and_sig_as_C_string(), old_flags, new_flags);
1140 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_METHOD_MODIFIERS_CHANGED;
1141 }
1142 {
1143 u2 new_num = k_new_method->method_idnum();
1144 u2 old_num = k_old_method->method_idnum();
1145 if (new_num != old_num) {
1146 Method* idnum_owner = scratch_class->method_with_idnum(old_num);
1147 if (idnum_owner != NULL) {
1148 // There is already a method assigned this idnum -- switch them
1149 // Take current and original idnum from the new_method
1150 idnum_owner->set_method_idnum(new_num);
1151 idnum_owner->set_orig_method_idnum(k_new_method->orig_method_idnum());
1152 }
1153 // Take current and original idnum from the old_method
1154 k_new_method->set_method_idnum(old_num);
1155 k_new_method->set_orig_method_idnum(k_old_method->orig_method_idnum());
1156 if (thread->has_pending_exception()) {
1157 return JVMTI_ERROR_OUT_OF_MEMORY;
1158 }
1159 }
1160 }
1161 log_trace(redefine, class, normalize)
1162 ("Method matched: new: %s [%d] == old: %s [%d]",
1163 k_new_method->name_and_sig_as_C_string(), ni, k_old_method->name_and_sig_as_C_string(), oi);
1164 // advance to next pair of methods
1165 ++oi;
1166 ++ni;
1167 break;
1168 case added:
1169 // method added, see if it is OK
1170 if (!can_add_or_delete(k_new_method)) {
1171 log_info(redefine, class, normalize)
1172 ("redefined class %s methods error: added method: %s [%d]",
1173 the_class->external_name(), k_new_method->name_and_sig_as_C_string(), ni);
1174 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_METHOD_ADDED;
1175 }
1176 {
1177 u2 num = the_class->next_method_idnum();
1178 if (num == ConstMethod::UNSET_IDNUM) {
1179 // cannot add any more methods
1180 log_info(redefine, class, normalize)
1181 ("redefined class %s methods error: can't create ID for new method %s [%d]",
1182 the_class->external_name(), k_new_method->name_and_sig_as_C_string(), ni);
1183 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_METHOD_ADDED;
1184 }
1185 u2 new_num = k_new_method->method_idnum();
1186 Method* idnum_owner = scratch_class->method_with_idnum(num);
1187 if (idnum_owner != NULL) {
1188 // There is already a method assigned this idnum -- switch them
1189 // Take current and original idnum from the new_method
1190 idnum_owner->set_method_idnum(new_num);
1191 idnum_owner->set_orig_method_idnum(k_new_method->orig_method_idnum());
1192 }
1193 k_new_method->set_method_idnum(num);
1194 k_new_method->set_orig_method_idnum(num);
1195 if (thread->has_pending_exception()) {
1196 return JVMTI_ERROR_OUT_OF_MEMORY;
1197 }
1198 }
1199 log_trace(redefine, class, normalize)
1200 ("Method added: new: %s [%d]", k_new_method->name_and_sig_as_C_string(), ni);
1201 ++ni; // advance to next new method
1202 break;
1203 case deleted:
1204 // method deleted, see if it is OK
1205 if (!can_add_or_delete(k_old_method)) {
1206 log_info(redefine, class, normalize)
1207 ("redefined class %s methods error: deleted method %s [%d]",
1208 the_class->external_name(), k_old_method->name_and_sig_as_C_string(), oi);
1209 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_METHOD_DELETED;
1210 }
1211 log_trace(redefine, class, normalize)
1212 ("Method deleted: old: %s [%d]", k_old_method->name_and_sig_as_C_string(), oi);
1213 ++oi; // advance to next old method
1214 break;
1215 default:
1216 ShouldNotReachHere();
1217 }
1218 }
1219
1220 return JVMTI_ERROR_NONE;
1221 }
1222
1223
1224 // Find new constant pool index value for old constant pool index value
1225 // by seaching the index map. Returns zero (0) if there is no mapped
1226 // value for the old constant pool index.
1227 int VM_RedefineClasses::find_new_index(int old_index) {
1228 if (_index_map_count == 0) {
1229 // map is empty so nothing can be found
1230 return 0;
1231 }
1232
1233 if (old_index < 1 || old_index >= _index_map_p->length()) {
1234 // The old_index is out of range so it is not mapped. This should
1235 // not happen in regular constant pool merging use, but it can
1236 // happen if a corrupt annotation is processed.
1237 return 0;
1238 }
1239
1240 int value = _index_map_p->at(old_index);
1241 if (value == -1) {
1242 // the old_index is not mapped
1243 return 0;
1244 }
1245
1246 return value;
1247 } // end find_new_index()
1248
1249
1250 // Find new bootstrap specifier index value for old bootstrap specifier index
1251 // value by seaching the index map. Returns unused index (-1) if there is
1252 // no mapped value for the old bootstrap specifier index.
1253 int VM_RedefineClasses::find_new_operand_index(int old_index) {
1254 if (_operands_index_map_count == 0) {
1255 // map is empty so nothing can be found
1256 return -1;
1257 }
1258
1259 if (old_index == -1 || old_index >= _operands_index_map_p->length()) {
1260 // The old_index is out of range so it is not mapped.
1261 // This should not happen in regular constant pool merging use.
1262 return -1;
1263 }
1264
1265 int value = _operands_index_map_p->at(old_index);
1266 if (value == -1) {
1267 // the old_index is not mapped
1268 return -1;
1269 }
1270
1271 return value;
1272 } // end find_new_operand_index()
1273
1274
1275 // Returns true if the current mismatch is due to a resolved/unresolved
1276 // class pair. Otherwise, returns false.
1277 bool VM_RedefineClasses::is_unresolved_class_mismatch(const constantPoolHandle& cp1,
1278 int index1, const constantPoolHandle& cp2, int index2) {
1279
1280 jbyte t1 = cp1->tag_at(index1).value();
1281 if (t1 != JVM_CONSTANT_Class && t1 != JVM_CONSTANT_UnresolvedClass) {
1282 return false; // wrong entry type; not our special case
1283 }
1284
1285 jbyte t2 = cp2->tag_at(index2).value();
1286 if (t2 != JVM_CONSTANT_Class && t2 != JVM_CONSTANT_UnresolvedClass) {
1287 return false; // wrong entry type; not our special case
1288 }
1289
1290 if (t1 == t2) {
1291 return false; // not a mismatch; not our special case
1292 }
1293
1294 char *s1 = cp1->klass_name_at(index1)->as_C_string();
1295 char *s2 = cp2->klass_name_at(index2)->as_C_string();
1296 if (strcmp(s1, s2) != 0) {
1297 return false; // strings don't match; not our special case
1298 }
1299
1300 return true; // made it through the gauntlet; this is our special case
1301 } // end is_unresolved_class_mismatch()
1302
1303
1304 // The bug 6214132 caused the verification to fail.
1305 // 1. What's done in RedefineClasses() before verification:
1306 // a) A reference to the class being redefined (_the_class) and a
1307 // reference to new version of the class (_scratch_class) are
1308 // saved here for use during the bytecode verification phase of
1309 // RedefineClasses.
1310 // b) The _java_mirror field from _the_class is copied to the
1311 // _java_mirror field in _scratch_class. This means that a jclass
1312 // returned for _the_class or _scratch_class will refer to the
1313 // same Java mirror. The verifier will see the "one true mirror"
1314 // for the class being verified.
1315 // 2. See comments in JvmtiThreadState for what is done during verification.
1316
1317 class RedefineVerifyMark : public StackObj {
1318 private:
1319 JvmtiThreadState* _state;
1320 Klass* _scratch_class;
1321 Handle _scratch_mirror;
1322
1323 public:
1324
1325 RedefineVerifyMark(Klass* the_class, Klass* scratch_class,
1326 JvmtiThreadState* state) : _state(state), _scratch_class(scratch_class)
1327 {
1328 _state->set_class_versions_map(the_class, scratch_class);
1329 _scratch_mirror = Handle(_state->get_thread(), _scratch_class->java_mirror());
1330 _scratch_class->replace_java_mirror(the_class->java_mirror());
1331 }
1332
1333 ~RedefineVerifyMark() {
1334 // Restore the scratch class's mirror, so when scratch_class is removed
1335 // the correct mirror pointing to it can be cleared.
1336 _scratch_class->replace_java_mirror(_scratch_mirror());
1337 _state->clear_class_versions_map();
1338 }
1339 };
1340
1341
1342 jvmtiError VM_RedefineClasses::load_new_class_versions() {
1343
1344 // For consistency allocate memory using os::malloc wrapper.
1345 _scratch_classes = (InstanceKlass**)
1346 os::malloc(sizeof(InstanceKlass*) * _class_count, mtClass);
1347 if (_scratch_classes == NULL) {
1348 return JVMTI_ERROR_OUT_OF_MEMORY;
1349 }
1350 // Zero initialize the _scratch_classes array.
1351 for (int i = 0; i < _class_count; i++) {
1352 _scratch_classes[i] = NULL;
1353 }
1354
1355 JavaThread* current = JavaThread::current();
1356 ResourceMark rm(current);
1357
1358 JvmtiThreadState *state = JvmtiThreadState::state_for(current);
1359 // state can only be NULL if the current thread is exiting which
1360 // should not happen since we're trying to do a RedefineClasses
1361 guarantee(state != NULL, "exiting thread calling load_new_class_versions");
1362 for (int i = 0; i < _class_count; i++) {
1363 // Create HandleMark so that any handles created while loading new class
1364 // versions are deleted. Constant pools are deallocated while merging
1365 // constant pools
1366 HandleMark hm(current);
1367 InstanceKlass* the_class = get_ik(_class_defs[i].klass);
1368
1369 log_debug(redefine, class, load)
1370 ("loading name=%s kind=%d (avail_mem=" UINT64_FORMAT "K)",
1371 the_class->external_name(), _class_load_kind, os::available_memory() >> 10);
1372
1373 ClassFileStream st((u1*)_class_defs[i].class_bytes,
1374 _class_defs[i].class_byte_count,
1375 "__VM_RedefineClasses__",
1376 ClassFileStream::verify);
1377
1378 // Set redefined class handle in JvmtiThreadState class.
1379 // This redefined class is sent to agent event handler for class file
1380 // load hook event.
1381 state->set_class_being_redefined(the_class, _class_load_kind);
1382
1383 JavaThread* THREAD = current; // For exception macros.
1384 ExceptionMark em(THREAD);
1385 Handle protection_domain(THREAD, the_class->protection_domain());
1386 ClassLoadInfo cl_info(protection_domain);
1387 // Parse and create a class from the bytes, but this class isn't added
1388 // to the dictionary, so do not call resolve_from_stream.
1389 InstanceKlass* scratch_class = KlassFactory::create_from_stream(&st,
1390 the_class->name(),
1391 the_class->class_loader_data(),
1392 cl_info,
1393 THREAD);
1394
1395 // Clear class_being_redefined just to be sure.
1396 state->clear_class_being_redefined();
1397
1398 // TODO: if this is retransform, and nothing changed we can skip it
1399
1400 // Need to clean up allocated InstanceKlass if there's an error so assign
1401 // the result here. Caller deallocates all the scratch classes in case of
1402 // an error.
1403 _scratch_classes[i] = scratch_class;
1404
1405 if (HAS_PENDING_EXCEPTION) {
1406 Symbol* ex_name = PENDING_EXCEPTION->klass()->name();
1407 log_info(redefine, class, load, exceptions)("create_from_stream exception: '%s'", ex_name->as_C_string());
1408 CLEAR_PENDING_EXCEPTION;
1409
1410 if (ex_name == vmSymbols::java_lang_UnsupportedClassVersionError()) {
1411 return JVMTI_ERROR_UNSUPPORTED_VERSION;
1412 } else if (ex_name == vmSymbols::java_lang_ClassFormatError()) {
1413 return JVMTI_ERROR_INVALID_CLASS_FORMAT;
1414 } else if (ex_name == vmSymbols::java_lang_ClassCircularityError()) {
1415 return JVMTI_ERROR_CIRCULAR_CLASS_DEFINITION;
1416 } else if (ex_name == vmSymbols::java_lang_NoClassDefFoundError()) {
1417 // The message will be "XXX (wrong name: YYY)"
1418 return JVMTI_ERROR_NAMES_DONT_MATCH;
1419 } else if (ex_name == vmSymbols::java_lang_OutOfMemoryError()) {
1420 return JVMTI_ERROR_OUT_OF_MEMORY;
1421 } else { // Just in case more exceptions can be thrown..
1422 return JVMTI_ERROR_FAILS_VERIFICATION;
1423 }
1424 }
1425
1426 // Ensure class is linked before redefine
1427 if (!the_class->is_linked()) {
1428 the_class->link_class(THREAD);
1429 if (HAS_PENDING_EXCEPTION) {
1430 Symbol* ex_name = PENDING_EXCEPTION->klass()->name();
1431 oop message = java_lang_Throwable::message(PENDING_EXCEPTION);
1432 if (message != NULL) {
1433 char* ex_msg = java_lang_String::as_utf8_string(message);
1434 log_info(redefine, class, load, exceptions)("link_class exception: '%s %s'",
1435 ex_name->as_C_string(), ex_msg);
1436 } else {
1437 log_info(redefine, class, load, exceptions)("link_class exception: '%s'",
1438 ex_name->as_C_string());
1439 }
1440 CLEAR_PENDING_EXCEPTION;
1441 if (ex_name == vmSymbols::java_lang_OutOfMemoryError()) {
1442 return JVMTI_ERROR_OUT_OF_MEMORY;
1443 } else if (ex_name == vmSymbols::java_lang_NoClassDefFoundError()) {
1444 return JVMTI_ERROR_INVALID_CLASS;
1445 } else {
1446 return JVMTI_ERROR_INTERNAL;
1447 }
1448 }
1449 }
1450
1451 // Do the validity checks in compare_and_normalize_class_versions()
1452 // before verifying the byte codes. By doing these checks first, we
1453 // limit the number of functions that require redirection from
1454 // the_class to scratch_class. In particular, we don't have to
1455 // modify JNI GetSuperclass() and thus won't change its performance.
1456 jvmtiError res = compare_and_normalize_class_versions(the_class,
1457 scratch_class);
1458 if (res != JVMTI_ERROR_NONE) {
1459 return res;
1460 }
1461
1462 // verify what the caller passed us
1463 {
1464 // The bug 6214132 caused the verification to fail.
1465 // Information about the_class and scratch_class is temporarily
1466 // recorded into jvmtiThreadState. This data is used to redirect
1467 // the_class to scratch_class in the JVM_* functions called by the
1468 // verifier. Please, refer to jvmtiThreadState.hpp for the detailed
1469 // description.
1470 RedefineVerifyMark rvm(the_class, scratch_class, state);
1471 Verifier::verify(scratch_class, true, THREAD);
1472 }
1473
1474 if (HAS_PENDING_EXCEPTION) {
1475 Symbol* ex_name = PENDING_EXCEPTION->klass()->name();
1476 log_info(redefine, class, load, exceptions)("verify_byte_codes exception: '%s'", ex_name->as_C_string());
1477 CLEAR_PENDING_EXCEPTION;
1478 if (ex_name == vmSymbols::java_lang_OutOfMemoryError()) {
1479 return JVMTI_ERROR_OUT_OF_MEMORY;
1480 } else {
1481 // tell the caller the bytecodes are bad
1482 return JVMTI_ERROR_FAILS_VERIFICATION;
1483 }
1484 }
1485
1486 res = merge_cp_and_rewrite(the_class, scratch_class, THREAD);
1487 if (HAS_PENDING_EXCEPTION) {
1488 Symbol* ex_name = PENDING_EXCEPTION->klass()->name();
1489 log_info(redefine, class, load, exceptions)("merge_cp_and_rewrite exception: '%s'", ex_name->as_C_string());
1490 CLEAR_PENDING_EXCEPTION;
1491 if (ex_name == vmSymbols::java_lang_OutOfMemoryError()) {
1492 return JVMTI_ERROR_OUT_OF_MEMORY;
1493 } else {
1494 return JVMTI_ERROR_INTERNAL;
1495 }
1496 }
1497
1498 #ifdef ASSERT
1499 {
1500 // verify what we have done during constant pool merging
1501 {
1502 RedefineVerifyMark rvm(the_class, scratch_class, state);
1503 Verifier::verify(scratch_class, true, THREAD);
1504 }
1505
1506 if (HAS_PENDING_EXCEPTION) {
1507 Symbol* ex_name = PENDING_EXCEPTION->klass()->name();
1508 log_info(redefine, class, load, exceptions)
1509 ("verify_byte_codes post merge-CP exception: '%s'", ex_name->as_C_string());
1510 CLEAR_PENDING_EXCEPTION;
1511 if (ex_name == vmSymbols::java_lang_OutOfMemoryError()) {
1512 return JVMTI_ERROR_OUT_OF_MEMORY;
1513 } else {
1514 // tell the caller that constant pool merging screwed up
1515 return JVMTI_ERROR_INTERNAL;
1516 }
1517 }
1518 }
1519 #endif // ASSERT
1520
1521 Rewriter::rewrite(scratch_class, THREAD);
1522 if (!HAS_PENDING_EXCEPTION) {
1523 scratch_class->link_methods(THREAD);
1524 }
1525 if (HAS_PENDING_EXCEPTION) {
1526 Symbol* ex_name = PENDING_EXCEPTION->klass()->name();
1527 log_info(redefine, class, load, exceptions)
1528 ("Rewriter::rewrite or link_methods exception: '%s'", ex_name->as_C_string());
1529 CLEAR_PENDING_EXCEPTION;
1530 if (ex_name == vmSymbols::java_lang_OutOfMemoryError()) {
1531 return JVMTI_ERROR_OUT_OF_MEMORY;
1532 } else {
1533 return JVMTI_ERROR_INTERNAL;
1534 }
1535 }
1536
1537 log_debug(redefine, class, load)
1538 ("loaded name=%s (avail_mem=" UINT64_FORMAT "K)", the_class->external_name(), os::available_memory() >> 10);
1539 }
1540
1541 return JVMTI_ERROR_NONE;
1542 }
1543
1544
1545 // Map old_index to new_index as needed. scratch_cp is only needed
1546 // for log calls.
1547 void VM_RedefineClasses::map_index(const constantPoolHandle& scratch_cp,
1548 int old_index, int new_index) {
1549 if (find_new_index(old_index) != 0) {
1550 // old_index is already mapped
1551 return;
1552 }
1553
1554 if (old_index == new_index) {
1555 // no mapping is needed
1556 return;
1557 }
1558
1559 _index_map_p->at_put(old_index, new_index);
1560 _index_map_count++;
1561
1562 log_trace(redefine, class, constantpool)
1563 ("mapped tag %d at index %d to %d", scratch_cp->tag_at(old_index).value(), old_index, new_index);
1564 } // end map_index()
1565
1566
1567 // Map old_index to new_index as needed.
1568 void VM_RedefineClasses::map_operand_index(int old_index, int new_index) {
1569 if (find_new_operand_index(old_index) != -1) {
1570 // old_index is already mapped
1571 return;
1572 }
1573
1574 if (old_index == new_index) {
1575 // no mapping is needed
1576 return;
1577 }
1578
1579 _operands_index_map_p->at_put(old_index, new_index);
1580 _operands_index_map_count++;
1581
1582 log_trace(redefine, class, constantpool)("mapped bootstrap specifier at index %d to %d", old_index, new_index);
1583 } // end map_index()
1584
1585
1586 // Merge old_cp and scratch_cp and return the results of the merge via
1587 // merge_cp_p. The number of entries in *merge_cp_p is returned via
1588 // merge_cp_length_p. The entries in old_cp occupy the same locations
1589 // in *merge_cp_p. Also creates a map of indices from entries in
1590 // scratch_cp to the corresponding entry in *merge_cp_p. Index map
1591 // entries are only created for entries in scratch_cp that occupy a
1592 // different location in *merged_cp_p.
1593 bool VM_RedefineClasses::merge_constant_pools(const constantPoolHandle& old_cp,
1594 const constantPoolHandle& scratch_cp, constantPoolHandle *merge_cp_p,
1595 int *merge_cp_length_p, TRAPS) {
1596
1597 if (merge_cp_p == NULL) {
1598 assert(false, "caller must provide scratch constantPool");
1599 return false; // robustness
1600 }
1601 if (merge_cp_length_p == NULL) {
1602 assert(false, "caller must provide scratch CP length");
1603 return false; // robustness
1604 }
1605 // Worst case we need old_cp->length() + scratch_cp()->length(),
1606 // but the caller might be smart so make sure we have at least
1607 // the minimum.
1608 if ((*merge_cp_p)->length() < old_cp->length()) {
1609 assert(false, "merge area too small");
1610 return false; // robustness
1611 }
1612
1613 log_info(redefine, class, constantpool)("old_cp_len=%d, scratch_cp_len=%d", old_cp->length(), scratch_cp->length());
1614
1615 {
1616 // Pass 0:
1617 // The old_cp is copied to *merge_cp_p; this means that any code
1618 // using old_cp does not have to change. This work looks like a
1619 // perfect fit for ConstantPool*::copy_cp_to(), but we need to
1620 // handle one special case:
1621 // - revert JVM_CONSTANT_Class to JVM_CONSTANT_UnresolvedClass
1622 // This will make verification happy.
1623
1624 int old_i; // index into old_cp
1625
1626 // index zero (0) is not used in constantPools
1627 for (old_i = 1; old_i < old_cp->length(); old_i++) {
1628 // leave debugging crumb
1629 jbyte old_tag = old_cp->tag_at(old_i).value();
1630 switch (old_tag) {
1631 case JVM_CONSTANT_Class:
1632 case JVM_CONSTANT_UnresolvedClass:
1633 // revert the copy to JVM_CONSTANT_UnresolvedClass
1634 // May be resolving while calling this so do the same for
1635 // JVM_CONSTANT_UnresolvedClass (klass_name_at() deals with transition)
1636 (*merge_cp_p)->temp_unresolved_klass_at_put(old_i,
1637 old_cp->klass_name_index_at(old_i));
1638 break;
1639
1640 case JVM_CONSTANT_Double:
1641 case JVM_CONSTANT_Long:
1642 // just copy the entry to *merge_cp_p, but double and long take
1643 // two constant pool entries
1644 ConstantPool::copy_entry_to(old_cp, old_i, *merge_cp_p, old_i);
1645 old_i++;
1646 break;
1647
1648 default:
1649 // just copy the entry to *merge_cp_p
1650 ConstantPool::copy_entry_to(old_cp, old_i, *merge_cp_p, old_i);
1651 break;
1652 }
1653 } // end for each old_cp entry
1654
1655 ConstantPool::copy_operands(old_cp, *merge_cp_p, CHECK_false);
1656 (*merge_cp_p)->extend_operands(scratch_cp, CHECK_false);
1657
1658 // We don't need to sanity check that *merge_cp_length_p is within
1659 // *merge_cp_p bounds since we have the minimum on-entry check above.
1660 (*merge_cp_length_p) = old_i;
1661 }
1662
1663 // merge_cp_len should be the same as old_cp->length() at this point
1664 // so this trace message is really a "warm-and-breathing" message.
1665 log_debug(redefine, class, constantpool)("after pass 0: merge_cp_len=%d", *merge_cp_length_p);
1666
1667 int scratch_i; // index into scratch_cp
1668 {
1669 // Pass 1a:
1670 // Compare scratch_cp entries to the old_cp entries that we have
1671 // already copied to *merge_cp_p. In this pass, we are eliminating
1672 // exact duplicates (matching entry at same index) so we only
1673 // compare entries in the common indice range.
1674 int increment = 1;
1675 int pass1a_length = MIN2(old_cp->length(), scratch_cp->length());
1676 for (scratch_i = 1; scratch_i < pass1a_length; scratch_i += increment) {
1677 switch (scratch_cp->tag_at(scratch_i).value()) {
1678 case JVM_CONSTANT_Double:
1679 case JVM_CONSTANT_Long:
1680 // double and long take two constant pool entries
1681 increment = 2;
1682 break;
1683
1684 default:
1685 increment = 1;
1686 break;
1687 }
1688
1689 bool match = scratch_cp->compare_entry_to(scratch_i, *merge_cp_p, scratch_i);
1690 if (match) {
1691 // found a match at the same index so nothing more to do
1692 continue;
1693 } else if (is_unresolved_class_mismatch(scratch_cp, scratch_i,
1694 *merge_cp_p, scratch_i)) {
1695 // The mismatch in compare_entry_to() above is because of a
1696 // resolved versus unresolved class entry at the same index
1697 // with the same string value. Since Pass 0 reverted any
1698 // class entries to unresolved class entries in *merge_cp_p,
1699 // we go with the unresolved class entry.
1700 continue;
1701 }
1702
1703 int found_i = scratch_cp->find_matching_entry(scratch_i, *merge_cp_p);
1704 if (found_i != 0) {
1705 guarantee(found_i != scratch_i,
1706 "compare_entry_to() and find_matching_entry() do not agree");
1707
1708 // Found a matching entry somewhere else in *merge_cp_p so
1709 // just need a mapping entry.
1710 map_index(scratch_cp, scratch_i, found_i);
1711 continue;
1712 }
1713
1714 // The find_matching_entry() call above could fail to find a match
1715 // due to a resolved versus unresolved class or string entry situation
1716 // like we solved above with the is_unresolved_*_mismatch() calls.
1717 // However, we would have to call is_unresolved_*_mismatch() over
1718 // all of *merge_cp_p (potentially) and that doesn't seem to be
1719 // worth the time.
1720
1721 // No match found so we have to append this entry and any unique
1722 // referenced entries to *merge_cp_p.
1723 append_entry(scratch_cp, scratch_i, merge_cp_p, merge_cp_length_p);
1724 }
1725 }
1726
1727 log_debug(redefine, class, constantpool)
1728 ("after pass 1a: merge_cp_len=%d, scratch_i=%d, index_map_len=%d",
1729 *merge_cp_length_p, scratch_i, _index_map_count);
1730
1731 if (scratch_i < scratch_cp->length()) {
1732 // Pass 1b:
1733 // old_cp is smaller than scratch_cp so there are entries in
1734 // scratch_cp that we have not yet processed. We take care of
1735 // those now.
1736 int increment = 1;
1737 for (; scratch_i < scratch_cp->length(); scratch_i += increment) {
1738 switch (scratch_cp->tag_at(scratch_i).value()) {
1739 case JVM_CONSTANT_Double:
1740 case JVM_CONSTANT_Long:
1741 // double and long take two constant pool entries
1742 increment = 2;
1743 break;
1744
1745 default:
1746 increment = 1;
1747 break;
1748 }
1749
1750 int found_i =
1751 scratch_cp->find_matching_entry(scratch_i, *merge_cp_p);
1752 if (found_i != 0) {
1753 // Found a matching entry somewhere else in *merge_cp_p so
1754 // just need a mapping entry.
1755 map_index(scratch_cp, scratch_i, found_i);
1756 continue;
1757 }
1758
1759 // No match found so we have to append this entry and any unique
1760 // referenced entries to *merge_cp_p.
1761 append_entry(scratch_cp, scratch_i, merge_cp_p, merge_cp_length_p);
1762 }
1763
1764 log_debug(redefine, class, constantpool)
1765 ("after pass 1b: merge_cp_len=%d, scratch_i=%d, index_map_len=%d",
1766 *merge_cp_length_p, scratch_i, _index_map_count);
1767 }
1768 finalize_operands_merge(*merge_cp_p, CHECK_false);
1769
1770 return true;
1771 } // end merge_constant_pools()
1772
1773
1774 // Scoped object to clean up the constant pool(s) created for merging
1775 class MergeCPCleaner {
1776 ClassLoaderData* _loader_data;
1777 ConstantPool* _cp;
1778 ConstantPool* _scratch_cp;
1779 public:
1780 MergeCPCleaner(ClassLoaderData* loader_data, ConstantPool* merge_cp) :
1781 _loader_data(loader_data), _cp(merge_cp), _scratch_cp(NULL) {}
1782 ~MergeCPCleaner() {
1783 _loader_data->add_to_deallocate_list(_cp);
1784 if (_scratch_cp != NULL) {
1785 _loader_data->add_to_deallocate_list(_scratch_cp);
1786 }
1787 }
1788 void add_scratch_cp(ConstantPool* scratch_cp) { _scratch_cp = scratch_cp; }
1789 };
1790
1791 // Merge constant pools between the_class and scratch_class and
1792 // potentially rewrite bytecodes in scratch_class to use the merged
1793 // constant pool.
1794 jvmtiError VM_RedefineClasses::merge_cp_and_rewrite(
1795 InstanceKlass* the_class, InstanceKlass* scratch_class,
1796 TRAPS) {
1797 // worst case merged constant pool length is old and new combined
1798 int merge_cp_length = the_class->constants()->length()
1799 + scratch_class->constants()->length();
1800
1801 // Constant pools are not easily reused so we allocate a new one
1802 // each time.
1803 // merge_cp is created unsafe for concurrent GC processing. It
1804 // should be marked safe before discarding it. Even though
1805 // garbage, if it crosses a card boundary, it may be scanned
1806 // in order to find the start of the first complete object on the card.
1807 ClassLoaderData* loader_data = the_class->class_loader_data();
1808 ConstantPool* merge_cp_oop =
1809 ConstantPool::allocate(loader_data,
1810 merge_cp_length,
1811 CHECK_(JVMTI_ERROR_OUT_OF_MEMORY));
1812 MergeCPCleaner cp_cleaner(loader_data, merge_cp_oop);
1813
1814 HandleMark hm(THREAD); // make sure handles are cleared before
1815 // MergeCPCleaner clears out merge_cp_oop
1816 constantPoolHandle merge_cp(THREAD, merge_cp_oop);
1817
1818 // Get constants() from the old class because it could have been rewritten
1819 // while we were at a safepoint allocating a new constant pool.
1820 constantPoolHandle old_cp(THREAD, the_class->constants());
1821 constantPoolHandle scratch_cp(THREAD, scratch_class->constants());
1822
1823 // If the length changed, the class was redefined out from under us. Return
1824 // an error.
1825 if (merge_cp_length != the_class->constants()->length()
1826 + scratch_class->constants()->length()) {
1827 return JVMTI_ERROR_INTERNAL;
1828 }
1829
1830 // Update the version number of the constant pools (may keep scratch_cp)
1831 merge_cp->increment_and_save_version(old_cp->version());
1832 scratch_cp->increment_and_save_version(old_cp->version());
1833
1834 ResourceMark rm(THREAD);
1835 _index_map_count = 0;
1836 _index_map_p = new intArray(scratch_cp->length(), scratch_cp->length(), -1);
1837
1838 _operands_cur_length = ConstantPool::operand_array_length(old_cp->operands());
1839 _operands_index_map_count = 0;
1840 int operands_index_map_len = ConstantPool::operand_array_length(scratch_cp->operands());
1841 _operands_index_map_p = new intArray(operands_index_map_len, operands_index_map_len, -1);
1842
1843 // reference to the cp holder is needed for copy_operands()
1844 merge_cp->set_pool_holder(scratch_class);
1845 bool result = merge_constant_pools(old_cp, scratch_cp, &merge_cp,
1846 &merge_cp_length, THREAD);
1847 merge_cp->set_pool_holder(NULL);
1848
1849 if (!result) {
1850 // The merge can fail due to memory allocation failure or due
1851 // to robustness checks.
1852 return JVMTI_ERROR_INTERNAL;
1853 }
1854
1855 // Set dynamic constants attribute from the original CP.
1856 if (old_cp->has_dynamic_constant()) {
1857 scratch_cp->set_has_dynamic_constant();
1858 }
1859 // Copy attributes from scratch_cp to merge_cp
1860 merge_cp->copy_fields(scratch_cp());
1861
1862 log_info(redefine, class, constantpool)("merge_cp_len=%d, index_map_len=%d", merge_cp_length, _index_map_count);
1863
1864 if (_index_map_count == 0) {
1865 // there is nothing to map between the new and merged constant pools
1866
1867 if (old_cp->length() == scratch_cp->length()) {
1868 // The old and new constant pools are the same length and the
1869 // index map is empty. This means that the three constant pools
1870 // are equivalent (but not the same). Unfortunately, the new
1871 // constant pool has not gone through link resolution nor have
1872 // the new class bytecodes gone through constant pool cache
1873 // rewriting so we can't use the old constant pool with the new
1874 // class.
1875
1876 // toss the merged constant pool at return
1877 } else if (old_cp->length() < scratch_cp->length()) {
1878 // The old constant pool has fewer entries than the new constant
1879 // pool and the index map is empty. This means the new constant
1880 // pool is a superset of the old constant pool. However, the old
1881 // class bytecodes have already gone through constant pool cache
1882 // rewriting so we can't use the new constant pool with the old
1883 // class.
1884
1885 // toss the merged constant pool at return
1886 } else {
1887 // The old constant pool has more entries than the new constant
1888 // pool and the index map is empty. This means that both the old
1889 // and merged constant pools are supersets of the new constant
1890 // pool.
1891
1892 // Replace the new constant pool with a shrunken copy of the
1893 // merged constant pool
1894 set_new_constant_pool(loader_data, scratch_class, merge_cp, merge_cp_length,
1895 CHECK_(JVMTI_ERROR_OUT_OF_MEMORY));
1896 // The new constant pool replaces scratch_cp so have cleaner clean it up.
1897 // It can't be cleaned up while there are handles to it.
1898 cp_cleaner.add_scratch_cp(scratch_cp());
1899 }
1900 } else {
1901 if (log_is_enabled(Trace, redefine, class, constantpool)) {
1902 // don't want to loop unless we are tracing
1903 int count = 0;
1904 for (int i = 1; i < _index_map_p->length(); i++) {
1905 int value = _index_map_p->at(i);
1906
1907 if (value != -1) {
1908 log_trace(redefine, class, constantpool)("index_map[%d]: old=%d new=%d", count, i, value);
1909 count++;
1910 }
1911 }
1912 }
1913
1914 // We have entries mapped between the new and merged constant pools
1915 // so we have to rewrite some constant pool references.
1916 if (!rewrite_cp_refs(scratch_class)) {
1917 return JVMTI_ERROR_INTERNAL;
1918 }
1919
1920 // Replace the new constant pool with a shrunken copy of the
1921 // merged constant pool so now the rewritten bytecodes have
1922 // valid references; the previous new constant pool will get
1923 // GCed.
1924 set_new_constant_pool(loader_data, scratch_class, merge_cp, merge_cp_length,
1925 CHECK_(JVMTI_ERROR_OUT_OF_MEMORY));
1926 // The new constant pool replaces scratch_cp so have cleaner clean it up.
1927 // It can't be cleaned up while there are handles to it.
1928 cp_cleaner.add_scratch_cp(scratch_cp());
1929 }
1930
1931 return JVMTI_ERROR_NONE;
1932 } // end merge_cp_and_rewrite()
1933
1934
1935 // Rewrite constant pool references in klass scratch_class.
1936 bool VM_RedefineClasses::rewrite_cp_refs(InstanceKlass* scratch_class) {
1937
1938 // rewrite constant pool references in the nest attributes:
1939 if (!rewrite_cp_refs_in_nest_attributes(scratch_class)) {
1940 // propagate failure back to caller
1941 return false;
1942 }
1943
1944 // rewrite constant pool references in the Record attribute:
1945 if (!rewrite_cp_refs_in_record_attribute(scratch_class)) {
1946 // propagate failure back to caller
1947 return false;
1948 }
1949
1950 // rewrite constant pool references in the PermittedSubclasses attribute:
1951 if (!rewrite_cp_refs_in_permitted_subclasses_attribute(scratch_class)) {
1952 // propagate failure back to caller
1953 return false;
1954 }
1955
1956 // rewrite constant pool references in the methods:
1957 if (!rewrite_cp_refs_in_methods(scratch_class)) {
1958 // propagate failure back to caller
1959 return false;
1960 }
1961
1962 // rewrite constant pool references in the class_annotations:
1963 if (!rewrite_cp_refs_in_class_annotations(scratch_class)) {
1964 // propagate failure back to caller
1965 return false;
1966 }
1967
1968 // rewrite constant pool references in the fields_annotations:
1969 if (!rewrite_cp_refs_in_fields_annotations(scratch_class)) {
1970 // propagate failure back to caller
1971 return false;
1972 }
1973
1974 // rewrite constant pool references in the methods_annotations:
1975 if (!rewrite_cp_refs_in_methods_annotations(scratch_class)) {
1976 // propagate failure back to caller
1977 return false;
1978 }
1979
1980 // rewrite constant pool references in the methods_parameter_annotations:
1981 if (!rewrite_cp_refs_in_methods_parameter_annotations(scratch_class)) {
1982 // propagate failure back to caller
1983 return false;
1984 }
1985
1986 // rewrite constant pool references in the methods_default_annotations:
1987 if (!rewrite_cp_refs_in_methods_default_annotations(scratch_class)) {
1988 // propagate failure back to caller
1989 return false;
1990 }
1991
1992 // rewrite constant pool references in the class_type_annotations:
1993 if (!rewrite_cp_refs_in_class_type_annotations(scratch_class)) {
1994 // propagate failure back to caller
1995 return false;
1996 }
1997
1998 // rewrite constant pool references in the fields_type_annotations:
1999 if (!rewrite_cp_refs_in_fields_type_annotations(scratch_class)) {
2000 // propagate failure back to caller
2001 return false;
2002 }
2003
2004 // rewrite constant pool references in the methods_type_annotations:
2005 if (!rewrite_cp_refs_in_methods_type_annotations(scratch_class)) {
2006 // propagate failure back to caller
2007 return false;
2008 }
2009
2010 // There can be type annotations in the Code part of a method_info attribute.
2011 // These annotations are not accessible, even by reflection.
2012 // Currently they are not even parsed by the ClassFileParser.
2013 // If runtime access is added they will also need to be rewritten.
2014
2015 // rewrite source file name index:
2016 u2 source_file_name_idx = scratch_class->source_file_name_index();
2017 if (source_file_name_idx != 0) {
2018 u2 new_source_file_name_idx = find_new_index(source_file_name_idx);
2019 if (new_source_file_name_idx != 0) {
2020 scratch_class->set_source_file_name_index(new_source_file_name_idx);
2021 }
2022 }
2023
2024 // rewrite class generic signature index:
2025 u2 generic_signature_index = scratch_class->generic_signature_index();
2026 if (generic_signature_index != 0) {
2027 u2 new_generic_signature_index = find_new_index(generic_signature_index);
2028 if (new_generic_signature_index != 0) {
2029 scratch_class->set_generic_signature_index(new_generic_signature_index);
2030 }
2031 }
2032
2033 return true;
2034 } // end rewrite_cp_refs()
2035
2036 // Rewrite constant pool references in the NestHost and NestMembers attributes.
2037 bool VM_RedefineClasses::rewrite_cp_refs_in_nest_attributes(
2038 InstanceKlass* scratch_class) {
2039
2040 u2 cp_index = scratch_class->nest_host_index();
2041 if (cp_index != 0) {
2042 scratch_class->set_nest_host_index(find_new_index(cp_index));
2043 }
2044 Array<u2>* nest_members = scratch_class->nest_members();
2045 for (int i = 0; i < nest_members->length(); i++) {
2046 u2 cp_index = nest_members->at(i);
2047 nest_members->at_put(i, find_new_index(cp_index));
2048 }
2049 return true;
2050 }
2051
2052 // Rewrite constant pool references in the Record attribute.
2053 bool VM_RedefineClasses::rewrite_cp_refs_in_record_attribute(InstanceKlass* scratch_class) {
2054 Array<RecordComponent*>* components = scratch_class->record_components();
2055 if (components != NULL) {
2056 for (int i = 0; i < components->length(); i++) {
2057 RecordComponent* component = components->at(i);
2058 u2 cp_index = component->name_index();
2059 component->set_name_index(find_new_index(cp_index));
2060 cp_index = component->descriptor_index();
2061 component->set_descriptor_index(find_new_index(cp_index));
2062 cp_index = component->generic_signature_index();
2063 if (cp_index != 0) {
2064 component->set_generic_signature_index(find_new_index(cp_index));
2065 }
2066
2067 AnnotationArray* annotations = component->annotations();
2068 if (annotations != NULL && annotations->length() != 0) {
2069 int byte_i = 0; // byte index into annotations
2070 if (!rewrite_cp_refs_in_annotations_typeArray(annotations, byte_i)) {
2071 log_debug(redefine, class, annotation)("bad record_component_annotations at %d", i);
2072 // propagate failure back to caller
2073 return false;
2074 }
2075 }
2076
2077 AnnotationArray* type_annotations = component->type_annotations();
2078 if (type_annotations != NULL && type_annotations->length() != 0) {
2079 int byte_i = 0; // byte index into annotations
2080 if (!rewrite_cp_refs_in_annotations_typeArray(type_annotations, byte_i)) {
2081 log_debug(redefine, class, annotation)("bad record_component_type_annotations at %d", i);
2082 // propagate failure back to caller
2083 return false;
2084 }
2085 }
2086 }
2087 }
2088 return true;
2089 }
2090
2091 // Rewrite constant pool references in the PermittedSubclasses attribute.
2092 bool VM_RedefineClasses::rewrite_cp_refs_in_permitted_subclasses_attribute(
2093 InstanceKlass* scratch_class) {
2094
2095 Array<u2>* permitted_subclasses = scratch_class->permitted_subclasses();
2096 assert(permitted_subclasses != NULL, "unexpected null permitted_subclasses");
2097 for (int i = 0; i < permitted_subclasses->length(); i++) {
2098 u2 cp_index = permitted_subclasses->at(i);
2099 permitted_subclasses->at_put(i, find_new_index(cp_index));
2100 }
2101 return true;
2102 }
2103
2104 // Rewrite constant pool references in the methods.
2105 bool VM_RedefineClasses::rewrite_cp_refs_in_methods(InstanceKlass* scratch_class) {
2106
2107 Array<Method*>* methods = scratch_class->methods();
2108
2109 if (methods == NULL || methods->length() == 0) {
2110 // no methods so nothing to do
2111 return true;
2112 }
2113
2114 JavaThread* THREAD = JavaThread::current(); // For exception macros.
2115 ExceptionMark em(THREAD);
2116
2117 // rewrite constant pool references in the methods:
2118 for (int i = methods->length() - 1; i >= 0; i--) {
2119 methodHandle method(THREAD, methods->at(i));
2120 methodHandle new_method;
2121 rewrite_cp_refs_in_method(method, &new_method, THREAD);
2122 if (!new_method.is_null()) {
2123 // the method has been replaced so save the new method version
2124 // even in the case of an exception. original method is on the
2125 // deallocation list.
2126 methods->at_put(i, new_method());
2127 }
2128 if (HAS_PENDING_EXCEPTION) {
2129 Symbol* ex_name = PENDING_EXCEPTION->klass()->name();
2130 log_info(redefine, class, load, exceptions)("rewrite_cp_refs_in_method exception: '%s'", ex_name->as_C_string());
2131 // Need to clear pending exception here as the super caller sets
2132 // the JVMTI_ERROR_INTERNAL if the returned value is false.
2133 CLEAR_PENDING_EXCEPTION;
2134 return false;
2135 }
2136 }
2137
2138 return true;
2139 }
2140
2141
2142 // Rewrite constant pool references in the specific method. This code
2143 // was adapted from Rewriter::rewrite_method().
2144 void VM_RedefineClasses::rewrite_cp_refs_in_method(methodHandle method,
2145 methodHandle *new_method_p, TRAPS) {
2146
2147 *new_method_p = methodHandle(); // default is no new method
2148
2149 // We cache a pointer to the bytecodes here in code_base. If GC
2150 // moves the Method*, then the bytecodes will also move which
2151 // will likely cause a crash. We create a NoSafepointVerifier
2152 // object to detect whether we pass a possible safepoint in this
2153 // code block.
2154 NoSafepointVerifier nsv;
2155
2156 // Bytecodes and their length
2157 address code_base = method->code_base();
2158 int code_length = method->code_size();
2159
2160 int bc_length;
2161 for (int bci = 0; bci < code_length; bci += bc_length) {
2162 address bcp = code_base + bci;
2163 Bytecodes::Code c = (Bytecodes::Code)(*bcp);
2164
2165 bc_length = Bytecodes::length_for(c);
2166 if (bc_length == 0) {
2167 // More complicated bytecodes report a length of zero so
2168 // we have to try again a slightly different way.
2169 bc_length = Bytecodes::length_at(method(), bcp);
2170 }
2171
2172 assert(bc_length != 0, "impossible bytecode length");
2173
2174 switch (c) {
2175 case Bytecodes::_ldc:
2176 {
2177 int cp_index = *(bcp + 1);
2178 int new_index = find_new_index(cp_index);
2179
2180 if (StressLdcRewrite && new_index == 0) {
2181 // If we are stressing ldc -> ldc_w rewriting, then we
2182 // always need a new_index value.
2183 new_index = cp_index;
2184 }
2185 if (new_index != 0) {
2186 // the original index is mapped so we have more work to do
2187 if (!StressLdcRewrite && new_index <= max_jubyte) {
2188 // The new value can still use ldc instead of ldc_w
2189 // unless we are trying to stress ldc -> ldc_w rewriting
2190 log_trace(redefine, class, constantpool)
2191 ("%s@" INTPTR_FORMAT " old=%d, new=%d", Bytecodes::name(c), p2i(bcp), cp_index, new_index);
2192 *(bcp + 1) = new_index;
2193 } else {
2194 log_trace(redefine, class, constantpool)
2195 ("%s->ldc_w@" INTPTR_FORMAT " old=%d, new=%d", Bytecodes::name(c), p2i(bcp), cp_index, new_index);
2196 // the new value needs ldc_w instead of ldc
2197 u_char inst_buffer[4]; // max instruction size is 4 bytes
2198 bcp = (address)inst_buffer;
2199 // construct new instruction sequence
2200 *bcp = Bytecodes::_ldc_w;
2201 bcp++;
2202 // Rewriter::rewrite_method() does not rewrite ldc -> ldc_w.
2203 // See comment below for difference between put_Java_u2()
2204 // and put_native_u2().
2205 Bytes::put_Java_u2(bcp, new_index);
2206
2207 Relocator rc(method, NULL /* no RelocatorListener needed */);
2208 methodHandle m;
2209 {
2210 PauseNoSafepointVerifier pnsv(&nsv);
2211
2212 // ldc is 2 bytes and ldc_w is 3 bytes
2213 m = rc.insert_space_at(bci, 3, inst_buffer, CHECK);
2214 }
2215
2216 // return the new method so that the caller can update
2217 // the containing class
2218 *new_method_p = method = m;
2219 // switch our bytecode processing loop from the old method
2220 // to the new method
2221 code_base = method->code_base();
2222 code_length = method->code_size();
2223 bcp = code_base + bci;
2224 c = (Bytecodes::Code)(*bcp);
2225 bc_length = Bytecodes::length_for(c);
2226 assert(bc_length != 0, "sanity check");
2227 } // end we need ldc_w instead of ldc
2228 } // end if there is a mapped index
2229 } break;
2230
2231 // these bytecodes have a two-byte constant pool index
2232 case Bytecodes::_anewarray : // fall through
2233 case Bytecodes::_checkcast : // fall through
2234 case Bytecodes::_getfield : // fall through
2235 case Bytecodes::_getstatic : // fall through
2236 case Bytecodes::_instanceof : // fall through
2237 case Bytecodes::_invokedynamic : // fall through
2238 case Bytecodes::_invokeinterface: // fall through
2239 case Bytecodes::_invokespecial : // fall through
2240 case Bytecodes::_invokestatic : // fall through
2241 case Bytecodes::_invokevirtual : // fall through
2242 case Bytecodes::_ldc_w : // fall through
2243 case Bytecodes::_ldc2_w : // fall through
2244 case Bytecodes::_multianewarray : // fall through
2245 case Bytecodes::_new : // fall through
2246 case Bytecodes::_putfield : // fall through
2247 case Bytecodes::_putstatic :
2248 {
2249 address p = bcp + 1;
2250 int cp_index = Bytes::get_Java_u2(p);
2251 int new_index = find_new_index(cp_index);
2252 if (new_index != 0) {
2253 // the original index is mapped so update w/ new value
2254 log_trace(redefine, class, constantpool)
2255 ("%s@" INTPTR_FORMAT " old=%d, new=%d", Bytecodes::name(c),p2i(bcp), cp_index, new_index);
2256 // Rewriter::rewrite_method() uses put_native_u2() in this
2257 // situation because it is reusing the constant pool index
2258 // location for a native index into the ConstantPoolCache.
2259 // Since we are updating the constant pool index prior to
2260 // verification and ConstantPoolCache initialization, we
2261 // need to keep the new index in Java byte order.
2262 Bytes::put_Java_u2(p, new_index);
2263 }
2264 } break;
2265 default:
2266 break;
2267 }
2268 } // end for each bytecode
2269
2270 // We also need to rewrite the parameter name indexes, if there is
2271 // method parameter data present
2272 if(method->has_method_parameters()) {
2273 const int len = method->method_parameters_length();
2274 MethodParametersElement* elem = method->method_parameters_start();
2275
2276 for (int i = 0; i < len; i++) {
2277 const u2 cp_index = elem[i].name_cp_index;
2278 const u2 new_cp_index = find_new_index(cp_index);
2279 if (new_cp_index != 0) {
2280 elem[i].name_cp_index = new_cp_index;
2281 }
2282 }
2283 }
2284 } // end rewrite_cp_refs_in_method()
2285
2286
2287 // Rewrite constant pool references in the class_annotations field.
2288 bool VM_RedefineClasses::rewrite_cp_refs_in_class_annotations(InstanceKlass* scratch_class) {
2289
2290 AnnotationArray* class_annotations = scratch_class->class_annotations();
2291 if (class_annotations == NULL || class_annotations->length() == 0) {
2292 // no class_annotations so nothing to do
2293 return true;
2294 }
2295
2296 log_debug(redefine, class, annotation)("class_annotations length=%d", class_annotations->length());
2297
2298 int byte_i = 0; // byte index into class_annotations
2299 return rewrite_cp_refs_in_annotations_typeArray(class_annotations, byte_i);
2300 }
2301
2302
2303 // Rewrite constant pool references in an annotations typeArray. This
2304 // "structure" is adapted from the RuntimeVisibleAnnotations_attribute
2305 // that is described in section 4.8.15 of the 2nd-edition of the VM spec:
2306 //
2307 // annotations_typeArray {
2308 // u2 num_annotations;
2309 // annotation annotations[num_annotations];
2310 // }
2311 //
2312 bool VM_RedefineClasses::rewrite_cp_refs_in_annotations_typeArray(
2313 AnnotationArray* annotations_typeArray, int &byte_i_ref) {
2314
2315 if ((byte_i_ref + 2) > annotations_typeArray->length()) {
2316 // not enough room for num_annotations field
2317 log_debug(redefine, class, annotation)("length() is too small for num_annotations field");
2318 return false;
2319 }
2320
2321 u2 num_annotations = Bytes::get_Java_u2((address)
2322 annotations_typeArray->adr_at(byte_i_ref));
2323 byte_i_ref += 2;
2324
2325 log_debug(redefine, class, annotation)("num_annotations=%d", num_annotations);
2326
2327 int calc_num_annotations = 0;
2328 for (; calc_num_annotations < num_annotations; calc_num_annotations++) {
2329 if (!rewrite_cp_refs_in_annotation_struct(annotations_typeArray, byte_i_ref)) {
2330 log_debug(redefine, class, annotation)("bad annotation_struct at %d", calc_num_annotations);
2331 // propagate failure back to caller
2332 return false;
2333 }
2334 }
2335 assert(num_annotations == calc_num_annotations, "sanity check");
2336
2337 return true;
2338 } // end rewrite_cp_refs_in_annotations_typeArray()
2339
2340
2341 // Rewrite constant pool references in the annotation struct portion of
2342 // an annotations_typeArray. This "structure" is from section 4.8.15 of
2343 // the 2nd-edition of the VM spec:
2344 //
2345 // struct annotation {
2346 // u2 type_index;
2347 // u2 num_element_value_pairs;
2348 // {
2349 // u2 element_name_index;
2350 // element_value value;
2351 // } element_value_pairs[num_element_value_pairs];
2352 // }
2353 //
2354 bool VM_RedefineClasses::rewrite_cp_refs_in_annotation_struct(
2355 AnnotationArray* annotations_typeArray, int &byte_i_ref) {
2356 if ((byte_i_ref + 2 + 2) > annotations_typeArray->length()) {
2357 // not enough room for smallest annotation_struct
2358 log_debug(redefine, class, annotation)("length() is too small for annotation_struct");
2359 return false;
2360 }
2361
2362 u2 type_index = rewrite_cp_ref_in_annotation_data(annotations_typeArray,
2363 byte_i_ref, "type_index");
2364
2365 u2 num_element_value_pairs = Bytes::get_Java_u2((address)
2366 annotations_typeArray->adr_at(byte_i_ref));
2367 byte_i_ref += 2;
2368
2369 log_debug(redefine, class, annotation)
2370 ("type_index=%d num_element_value_pairs=%d", type_index, num_element_value_pairs);
2371
2372 int calc_num_element_value_pairs = 0;
2373 for (; calc_num_element_value_pairs < num_element_value_pairs;
2374 calc_num_element_value_pairs++) {
2375 if ((byte_i_ref + 2) > annotations_typeArray->length()) {
2376 // not enough room for another element_name_index, let alone
2377 // the rest of another component
2378 log_debug(redefine, class, annotation)("length() is too small for element_name_index");
2379 return false;
2380 }
2381
2382 u2 element_name_index = rewrite_cp_ref_in_annotation_data(
2383 annotations_typeArray, byte_i_ref,
2384 "element_name_index");
2385
2386 log_debug(redefine, class, annotation)("element_name_index=%d", element_name_index);
2387
2388 if (!rewrite_cp_refs_in_element_value(annotations_typeArray, byte_i_ref)) {
2389 log_debug(redefine, class, annotation)("bad element_value at %d", calc_num_element_value_pairs);
2390 // propagate failure back to caller
2391 return false;
2392 }
2393 } // end for each component
2394 assert(num_element_value_pairs == calc_num_element_value_pairs,
2395 "sanity check");
2396
2397 return true;
2398 } // end rewrite_cp_refs_in_annotation_struct()
2399
2400
2401 // Rewrite a constant pool reference at the current position in
2402 // annotations_typeArray if needed. Returns the original constant
2403 // pool reference if a rewrite was not needed or the new constant
2404 // pool reference if a rewrite was needed.
2405 u2 VM_RedefineClasses::rewrite_cp_ref_in_annotation_data(
2406 AnnotationArray* annotations_typeArray, int &byte_i_ref,
2407 const char * trace_mesg) {
2408
2409 address cp_index_addr = (address)
2410 annotations_typeArray->adr_at(byte_i_ref);
2411 u2 old_cp_index = Bytes::get_Java_u2(cp_index_addr);
2412 u2 new_cp_index = find_new_index(old_cp_index);
2413 if (new_cp_index != 0) {
2414 log_debug(redefine, class, annotation)("mapped old %s=%d", trace_mesg, old_cp_index);
2415 Bytes::put_Java_u2(cp_index_addr, new_cp_index);
2416 old_cp_index = new_cp_index;
2417 }
2418 byte_i_ref += 2;
2419 return old_cp_index;
2420 }
2421
2422
2423 // Rewrite constant pool references in the element_value portion of an
2424 // annotations_typeArray. This "structure" is from section 4.8.15.1 of
2425 // the 2nd-edition of the VM spec:
2426 //
2427 // struct element_value {
2428 // u1 tag;
2429 // union {
2430 // u2 const_value_index;
2431 // {
2432 // u2 type_name_index;
2433 // u2 const_name_index;
2434 // } enum_const_value;
2435 // u2 class_info_index;
2436 // annotation annotation_value;
2437 // struct {
2438 // u2 num_values;
2439 // element_value values[num_values];
2440 // } array_value;
2441 // } value;
2442 // }
2443 //
2444 bool VM_RedefineClasses::rewrite_cp_refs_in_element_value(
2445 AnnotationArray* annotations_typeArray, int &byte_i_ref) {
2446
2447 if ((byte_i_ref + 1) > annotations_typeArray->length()) {
2448 // not enough room for a tag let alone the rest of an element_value
2449 log_debug(redefine, class, annotation)("length() is too small for a tag");
2450 return false;
2451 }
2452
2453 u1 tag = annotations_typeArray->at(byte_i_ref);
2454 byte_i_ref++;
2455 log_debug(redefine, class, annotation)("tag='%c'", tag);
2456
2457 switch (tag) {
2458 // These BaseType tag values are from Table 4.2 in VM spec:
2459 case JVM_SIGNATURE_BYTE:
2460 case JVM_SIGNATURE_CHAR:
2461 case JVM_SIGNATURE_DOUBLE:
2462 case JVM_SIGNATURE_FLOAT:
2463 case JVM_SIGNATURE_INT:
2464 case JVM_SIGNATURE_LONG:
2465 case JVM_SIGNATURE_SHORT:
2466 case JVM_SIGNATURE_BOOLEAN:
2467
2468 // The remaining tag values are from Table 4.8 in the 2nd-edition of
2469 // the VM spec:
2470 case 's':
2471 {
2472 // For the above tag values (including the BaseType values),
2473 // value.const_value_index is right union field.
2474
2475 if ((byte_i_ref + 2) > annotations_typeArray->length()) {
2476 // not enough room for a const_value_index
2477 log_debug(redefine, class, annotation)("length() is too small for a const_value_index");
2478 return false;
2479 }
2480
2481 u2 const_value_index = rewrite_cp_ref_in_annotation_data(
2482 annotations_typeArray, byte_i_ref,
2483 "const_value_index");
2484
2485 log_debug(redefine, class, annotation)("const_value_index=%d", const_value_index);
2486 } break;
2487
2488 case 'e':
2489 {
2490 // for the above tag value, value.enum_const_value is right union field
2491
2492 if ((byte_i_ref + 4) > annotations_typeArray->length()) {
2493 // not enough room for a enum_const_value
2494 log_debug(redefine, class, annotation)("length() is too small for a enum_const_value");
2495 return false;
2496 }
2497
2498 u2 type_name_index = rewrite_cp_ref_in_annotation_data(
2499 annotations_typeArray, byte_i_ref,
2500 "type_name_index");
2501
2502 u2 const_name_index = rewrite_cp_ref_in_annotation_data(
2503 annotations_typeArray, byte_i_ref,
2504 "const_name_index");
2505
2506 log_debug(redefine, class, annotation)
2507 ("type_name_index=%d const_name_index=%d", type_name_index, const_name_index);
2508 } break;
2509
2510 case 'c':
2511 {
2512 // for the above tag value, value.class_info_index is right union field
2513
2514 if ((byte_i_ref + 2) > annotations_typeArray->length()) {
2515 // not enough room for a class_info_index
2516 log_debug(redefine, class, annotation)("length() is too small for a class_info_index");
2517 return false;
2518 }
2519
2520 u2 class_info_index = rewrite_cp_ref_in_annotation_data(
2521 annotations_typeArray, byte_i_ref,
2522 "class_info_index");
2523
2524 log_debug(redefine, class, annotation)("class_info_index=%d", class_info_index);
2525 } break;
2526
2527 case '@':
2528 // For the above tag value, value.attr_value is the right union
2529 // field. This is a nested annotation.
2530 if (!rewrite_cp_refs_in_annotation_struct(annotations_typeArray, byte_i_ref)) {
2531 // propagate failure back to caller
2532 return false;
2533 }
2534 break;
2535
2536 case JVM_SIGNATURE_ARRAY:
2537 {
2538 if ((byte_i_ref + 2) > annotations_typeArray->length()) {
2539 // not enough room for a num_values field
2540 log_debug(redefine, class, annotation)("length() is too small for a num_values field");
2541 return false;
2542 }
2543
2544 // For the above tag value, value.array_value is the right union
2545 // field. This is an array of nested element_value.
2546 u2 num_values = Bytes::get_Java_u2((address)
2547 annotations_typeArray->adr_at(byte_i_ref));
2548 byte_i_ref += 2;
2549 log_debug(redefine, class, annotation)("num_values=%d", num_values);
2550
2551 int calc_num_values = 0;
2552 for (; calc_num_values < num_values; calc_num_values++) {
2553 if (!rewrite_cp_refs_in_element_value(annotations_typeArray, byte_i_ref)) {
2554 log_debug(redefine, class, annotation)("bad nested element_value at %d", calc_num_values);
2555 // propagate failure back to caller
2556 return false;
2557 }
2558 }
2559 assert(num_values == calc_num_values, "sanity check");
2560 } break;
2561
2562 default:
2563 log_debug(redefine, class, annotation)("bad tag=0x%x", tag);
2564 return false;
2565 } // end decode tag field
2566
2567 return true;
2568 } // end rewrite_cp_refs_in_element_value()
2569
2570
2571 // Rewrite constant pool references in a fields_annotations field.
2572 bool VM_RedefineClasses::rewrite_cp_refs_in_fields_annotations(
2573 InstanceKlass* scratch_class) {
2574
2575 Array<AnnotationArray*>* fields_annotations = scratch_class->fields_annotations();
2576
2577 if (fields_annotations == NULL || fields_annotations->length() == 0) {
2578 // no fields_annotations so nothing to do
2579 return true;
2580 }
2581
2582 log_debug(redefine, class, annotation)("fields_annotations length=%d", fields_annotations->length());
2583
2584 for (int i = 0; i < fields_annotations->length(); i++) {
2585 AnnotationArray* field_annotations = fields_annotations->at(i);
2586 if (field_annotations == NULL || field_annotations->length() == 0) {
2587 // this field does not have any annotations so skip it
2588 continue;
2589 }
2590
2591 int byte_i = 0; // byte index into field_annotations
2592 if (!rewrite_cp_refs_in_annotations_typeArray(field_annotations, byte_i)) {
2593 log_debug(redefine, class, annotation)("bad field_annotations at %d", i);
2594 // propagate failure back to caller
2595 return false;
2596 }
2597 }
2598
2599 return true;
2600 } // end rewrite_cp_refs_in_fields_annotations()
2601
2602
2603 // Rewrite constant pool references in a methods_annotations field.
2604 bool VM_RedefineClasses::rewrite_cp_refs_in_methods_annotations(
2605 InstanceKlass* scratch_class) {
2606
2607 for (int i = 0; i < scratch_class->methods()->length(); i++) {
2608 Method* m = scratch_class->methods()->at(i);
2609 AnnotationArray* method_annotations = m->constMethod()->method_annotations();
2610
2611 if (method_annotations == NULL || method_annotations->length() == 0) {
2612 // this method does not have any annotations so skip it
2613 continue;
2614 }
2615
2616 int byte_i = 0; // byte index into method_annotations
2617 if (!rewrite_cp_refs_in_annotations_typeArray(method_annotations, byte_i)) {
2618 log_debug(redefine, class, annotation)("bad method_annotations at %d", i);
2619 // propagate failure back to caller
2620 return false;
2621 }
2622 }
2623
2624 return true;
2625 } // end rewrite_cp_refs_in_methods_annotations()
2626
2627
2628 // Rewrite constant pool references in a methods_parameter_annotations
2629 // field. This "structure" is adapted from the
2630 // RuntimeVisibleParameterAnnotations_attribute described in section
2631 // 4.8.17 of the 2nd-edition of the VM spec:
2632 //
2633 // methods_parameter_annotations_typeArray {
2634 // u1 num_parameters;
2635 // {
2636 // u2 num_annotations;
2637 // annotation annotations[num_annotations];
2638 // } parameter_annotations[num_parameters];
2639 // }
2640 //
2641 bool VM_RedefineClasses::rewrite_cp_refs_in_methods_parameter_annotations(
2642 InstanceKlass* scratch_class) {
2643
2644 for (int i = 0; i < scratch_class->methods()->length(); i++) {
2645 Method* m = scratch_class->methods()->at(i);
2646 AnnotationArray* method_parameter_annotations = m->constMethod()->parameter_annotations();
2647 if (method_parameter_annotations == NULL
2648 || method_parameter_annotations->length() == 0) {
2649 // this method does not have any parameter annotations so skip it
2650 continue;
2651 }
2652
2653 if (method_parameter_annotations->length() < 1) {
2654 // not enough room for a num_parameters field
2655 log_debug(redefine, class, annotation)("length() is too small for a num_parameters field at %d", i);
2656 return false;
2657 }
2658
2659 int byte_i = 0; // byte index into method_parameter_annotations
2660
2661 u1 num_parameters = method_parameter_annotations->at(byte_i);
2662 byte_i++;
2663
2664 log_debug(redefine, class, annotation)("num_parameters=%d", num_parameters);
2665
2666 int calc_num_parameters = 0;
2667 for (; calc_num_parameters < num_parameters; calc_num_parameters++) {
2668 if (!rewrite_cp_refs_in_annotations_typeArray(method_parameter_annotations, byte_i)) {
2669 log_debug(redefine, class, annotation)("bad method_parameter_annotations at %d", calc_num_parameters);
2670 // propagate failure back to caller
2671 return false;
2672 }
2673 }
2674 assert(num_parameters == calc_num_parameters, "sanity check");
2675 }
2676
2677 return true;
2678 } // end rewrite_cp_refs_in_methods_parameter_annotations()
2679
2680
2681 // Rewrite constant pool references in a methods_default_annotations
2682 // field. This "structure" is adapted from the AnnotationDefault_attribute
2683 // that is described in section 4.8.19 of the 2nd-edition of the VM spec:
2684 //
2685 // methods_default_annotations_typeArray {
2686 // element_value default_value;
2687 // }
2688 //
2689 bool VM_RedefineClasses::rewrite_cp_refs_in_methods_default_annotations(
2690 InstanceKlass* scratch_class) {
2691
2692 for (int i = 0; i < scratch_class->methods()->length(); i++) {
2693 Method* m = scratch_class->methods()->at(i);
2694 AnnotationArray* method_default_annotations = m->constMethod()->default_annotations();
2695 if (method_default_annotations == NULL
2696 || method_default_annotations->length() == 0) {
2697 // this method does not have any default annotations so skip it
2698 continue;
2699 }
2700
2701 int byte_i = 0; // byte index into method_default_annotations
2702
2703 if (!rewrite_cp_refs_in_element_value(
2704 method_default_annotations, byte_i)) {
2705 log_debug(redefine, class, annotation)("bad default element_value at %d", i);
2706 // propagate failure back to caller
2707 return false;
2708 }
2709 }
2710
2711 return true;
2712 } // end rewrite_cp_refs_in_methods_default_annotations()
2713
2714
2715 // Rewrite constant pool references in a class_type_annotations field.
2716 bool VM_RedefineClasses::rewrite_cp_refs_in_class_type_annotations(
2717 InstanceKlass* scratch_class) {
2718
2719 AnnotationArray* class_type_annotations = scratch_class->class_type_annotations();
2720 if (class_type_annotations == NULL || class_type_annotations->length() == 0) {
2721 // no class_type_annotations so nothing to do
2722 return true;
2723 }
2724
2725 log_debug(redefine, class, annotation)("class_type_annotations length=%d", class_type_annotations->length());
2726
2727 int byte_i = 0; // byte index into class_type_annotations
2728 return rewrite_cp_refs_in_type_annotations_typeArray(class_type_annotations,
2729 byte_i, "ClassFile");
2730 } // end rewrite_cp_refs_in_class_type_annotations()
2731
2732
2733 // Rewrite constant pool references in a fields_type_annotations field.
2734 bool VM_RedefineClasses::rewrite_cp_refs_in_fields_type_annotations(InstanceKlass* scratch_class) {
2735
2736 Array<AnnotationArray*>* fields_type_annotations = scratch_class->fields_type_annotations();
2737 if (fields_type_annotations == NULL || fields_type_annotations->length() == 0) {
2738 // no fields_type_annotations so nothing to do
2739 return true;
2740 }
2741
2742 log_debug(redefine, class, annotation)("fields_type_annotations length=%d", fields_type_annotations->length());
2743
2744 for (int i = 0; i < fields_type_annotations->length(); i++) {
2745 AnnotationArray* field_type_annotations = fields_type_annotations->at(i);
2746 if (field_type_annotations == NULL || field_type_annotations->length() == 0) {
2747 // this field does not have any annotations so skip it
2748 continue;
2749 }
2750
2751 int byte_i = 0; // byte index into field_type_annotations
2752 if (!rewrite_cp_refs_in_type_annotations_typeArray(field_type_annotations,
2753 byte_i, "field_info")) {
2754 log_debug(redefine, class, annotation)("bad field_type_annotations at %d", i);
2755 // propagate failure back to caller
2756 return false;
2757 }
2758 }
2759
2760 return true;
2761 } // end rewrite_cp_refs_in_fields_type_annotations()
2762
2763
2764 // Rewrite constant pool references in a methods_type_annotations field.
2765 bool VM_RedefineClasses::rewrite_cp_refs_in_methods_type_annotations(
2766 InstanceKlass* scratch_class) {
2767
2768 for (int i = 0; i < scratch_class->methods()->length(); i++) {
2769 Method* m = scratch_class->methods()->at(i);
2770 AnnotationArray* method_type_annotations = m->constMethod()->type_annotations();
2771
2772 if (method_type_annotations == NULL || method_type_annotations->length() == 0) {
2773 // this method does not have any annotations so skip it
2774 continue;
2775 }
2776
2777 log_debug(redefine, class, annotation)("methods type_annotations length=%d", method_type_annotations->length());
2778
2779 int byte_i = 0; // byte index into method_type_annotations
2780 if (!rewrite_cp_refs_in_type_annotations_typeArray(method_type_annotations,
2781 byte_i, "method_info")) {
2782 log_debug(redefine, class, annotation)("bad method_type_annotations at %d", i);
2783 // propagate failure back to caller
2784 return false;
2785 }
2786 }
2787
2788 return true;
2789 } // end rewrite_cp_refs_in_methods_type_annotations()
2790
2791
2792 // Rewrite constant pool references in a type_annotations
2793 // field. This "structure" is adapted from the
2794 // RuntimeVisibleTypeAnnotations_attribute described in
2795 // section 4.7.20 of the Java SE 8 Edition of the VM spec:
2796 //
2797 // type_annotations_typeArray {
2798 // u2 num_annotations;
2799 // type_annotation annotations[num_annotations];
2800 // }
2801 //
2802 bool VM_RedefineClasses::rewrite_cp_refs_in_type_annotations_typeArray(
2803 AnnotationArray* type_annotations_typeArray, int &byte_i_ref,
2804 const char * location_mesg) {
2805
2806 if ((byte_i_ref + 2) > type_annotations_typeArray->length()) {
2807 // not enough room for num_annotations field
2808 log_debug(redefine, class, annotation)("length() is too small for num_annotations field");
2809 return false;
2810 }
2811
2812 u2 num_annotations = Bytes::get_Java_u2((address)
2813 type_annotations_typeArray->adr_at(byte_i_ref));
2814 byte_i_ref += 2;
2815
2816 log_debug(redefine, class, annotation)("num_type_annotations=%d", num_annotations);
2817
2818 int calc_num_annotations = 0;
2819 for (; calc_num_annotations < num_annotations; calc_num_annotations++) {
2820 if (!rewrite_cp_refs_in_type_annotation_struct(type_annotations_typeArray,
2821 byte_i_ref, location_mesg)) {
2822 log_debug(redefine, class, annotation)("bad type_annotation_struct at %d", calc_num_annotations);
2823 // propagate failure back to caller
2824 return false;
2825 }
2826 }
2827 assert(num_annotations == calc_num_annotations, "sanity check");
2828
2829 if (byte_i_ref != type_annotations_typeArray->length()) {
2830 log_debug(redefine, class, annotation)
2831 ("read wrong amount of bytes at end of processing type_annotations_typeArray (%d of %d bytes were read)",
2832 byte_i_ref, type_annotations_typeArray->length());
2833 return false;
2834 }
2835
2836 return true;
2837 } // end rewrite_cp_refs_in_type_annotations_typeArray()
2838
2839
2840 // Rewrite constant pool references in a type_annotation
2841 // field. This "structure" is adapted from the
2842 // RuntimeVisibleTypeAnnotations_attribute described in
2843 // section 4.7.20 of the Java SE 8 Edition of the VM spec:
2844 //
2845 // type_annotation {
2846 // u1 target_type;
2847 // union {
2848 // type_parameter_target;
2849 // supertype_target;
2850 // type_parameter_bound_target;
2851 // empty_target;
2852 // method_formal_parameter_target;
2853 // throws_target;
2854 // localvar_target;
2855 // catch_target;
2856 // offset_target;
2857 // type_argument_target;
2858 // } target_info;
2859 // type_path target_path;
2860 // annotation anno;
2861 // }
2862 //
2863 bool VM_RedefineClasses::rewrite_cp_refs_in_type_annotation_struct(
2864 AnnotationArray* type_annotations_typeArray, int &byte_i_ref,
2865 const char * location_mesg) {
2866
2867 if (!skip_type_annotation_target(type_annotations_typeArray,
2868 byte_i_ref, location_mesg)) {
2869 return false;
2870 }
2871
2872 if (!skip_type_annotation_type_path(type_annotations_typeArray, byte_i_ref)) {
2873 return false;
2874 }
2875
2876 if (!rewrite_cp_refs_in_annotation_struct(type_annotations_typeArray, byte_i_ref)) {
2877 return false;
2878 }
2879
2880 return true;
2881 } // end rewrite_cp_refs_in_type_annotation_struct()
2882
2883
2884 // Read, verify and skip over the target_type and target_info part
2885 // so that rewriting can continue in the later parts of the struct.
2886 //
2887 // u1 target_type;
2888 // union {
2889 // type_parameter_target;
2890 // supertype_target;
2891 // type_parameter_bound_target;
2892 // empty_target;
2893 // method_formal_parameter_target;
2894 // throws_target;
2895 // localvar_target;
2896 // catch_target;
2897 // offset_target;
2898 // type_argument_target;
2899 // } target_info;
2900 //
2901 bool VM_RedefineClasses::skip_type_annotation_target(
2902 AnnotationArray* type_annotations_typeArray, int &byte_i_ref,
2903 const char * location_mesg) {
2904
2905 if ((byte_i_ref + 1) > type_annotations_typeArray->length()) {
2906 // not enough room for a target_type let alone the rest of a type_annotation
2907 log_debug(redefine, class, annotation)("length() is too small for a target_type");
2908 return false;
2909 }
2910
2911 u1 target_type = type_annotations_typeArray->at(byte_i_ref);
2912 byte_i_ref += 1;
2913 log_debug(redefine, class, annotation)("target_type=0x%.2x", target_type);
2914 log_debug(redefine, class, annotation)("location=%s", location_mesg);
2915
2916 // Skip over target_info
2917 switch (target_type) {
2918 case 0x00:
2919 // kind: type parameter declaration of generic class or interface
2920 // location: ClassFile
2921 case 0x01:
2922 // kind: type parameter declaration of generic method or constructor
2923 // location: method_info
2924
2925 {
2926 // struct:
2927 // type_parameter_target {
2928 // u1 type_parameter_index;
2929 // }
2930 //
2931 if ((byte_i_ref + 1) > type_annotations_typeArray->length()) {
2932 log_debug(redefine, class, annotation)("length() is too small for a type_parameter_target");
2933 return false;
2934 }
2935
2936 u1 type_parameter_index = type_annotations_typeArray->at(byte_i_ref);
2937 byte_i_ref += 1;
2938
2939 log_debug(redefine, class, annotation)("type_parameter_target: type_parameter_index=%d", type_parameter_index);
2940 } break;
2941
2942 case 0x10:
2943 // kind: type in extends clause of class or interface declaration
2944 // or in implements clause of interface declaration
2945 // location: ClassFile
2946
2947 {
2948 // struct:
2949 // supertype_target {
2950 // u2 supertype_index;
2951 // }
2952 //
2953 if ((byte_i_ref + 2) > type_annotations_typeArray->length()) {
2954 log_debug(redefine, class, annotation)("length() is too small for a supertype_target");
2955 return false;
2956 }
2957
2958 u2 supertype_index = Bytes::get_Java_u2((address)
2959 type_annotations_typeArray->adr_at(byte_i_ref));
2960 byte_i_ref += 2;
2961
2962 log_debug(redefine, class, annotation)("supertype_target: supertype_index=%d", supertype_index);
2963 } break;
2964
2965 case 0x11:
2966 // kind: type in bound of type parameter declaration of generic class or interface
2967 // location: ClassFile
2968 case 0x12:
2969 // kind: type in bound of type parameter declaration of generic method or constructor
2970 // location: method_info
2971
2972 {
2973 // struct:
2974 // type_parameter_bound_target {
2975 // u1 type_parameter_index;
2976 // u1 bound_index;
2977 // }
2978 //
2979 if ((byte_i_ref + 2) > type_annotations_typeArray->length()) {
2980 log_debug(redefine, class, annotation)("length() is too small for a type_parameter_bound_target");
2981 return false;
2982 }
2983
2984 u1 type_parameter_index = type_annotations_typeArray->at(byte_i_ref);
2985 byte_i_ref += 1;
2986 u1 bound_index = type_annotations_typeArray->at(byte_i_ref);
2987 byte_i_ref += 1;
2988
2989 log_debug(redefine, class, annotation)
2990 ("type_parameter_bound_target: type_parameter_index=%d, bound_index=%d", type_parameter_index, bound_index);
2991 } break;
2992
2993 case 0x13:
2994 // kind: type in field declaration
2995 // location: field_info
2996 case 0x14:
2997 // kind: return type of method, or type of newly constructed object
2998 // location: method_info
2999 case 0x15:
3000 // kind: receiver type of method or constructor
3001 // location: method_info
3002
3003 {
3004 // struct:
3005 // empty_target {
3006 // }
3007 //
3008 log_debug(redefine, class, annotation)("empty_target");
3009 } break;
3010
3011 case 0x16:
3012 // kind: type in formal parameter declaration of method, constructor, or lambda expression
3013 // location: method_info
3014
3015 {
3016 // struct:
3017 // formal_parameter_target {
3018 // u1 formal_parameter_index;
3019 // }
3020 //
3021 if ((byte_i_ref + 1) > type_annotations_typeArray->length()) {
3022 log_debug(redefine, class, annotation)("length() is too small for a formal_parameter_target");
3023 return false;
3024 }
3025
3026 u1 formal_parameter_index = type_annotations_typeArray->at(byte_i_ref);
3027 byte_i_ref += 1;
3028
3029 log_debug(redefine, class, annotation)
3030 ("formal_parameter_target: formal_parameter_index=%d", formal_parameter_index);
3031 } break;
3032
3033 case 0x17:
3034 // kind: type in throws clause of method or constructor
3035 // location: method_info
3036
3037 {
3038 // struct:
3039 // throws_target {
3040 // u2 throws_type_index
3041 // }
3042 //
3043 if ((byte_i_ref + 2) > type_annotations_typeArray->length()) {
3044 log_debug(redefine, class, annotation)("length() is too small for a throws_target");
3045 return false;
3046 }
3047
3048 u2 throws_type_index = Bytes::get_Java_u2((address)
3049 type_annotations_typeArray->adr_at(byte_i_ref));
3050 byte_i_ref += 2;
3051
3052 log_debug(redefine, class, annotation)("throws_target: throws_type_index=%d", throws_type_index);
3053 } break;
3054
3055 case 0x40:
3056 // kind: type in local variable declaration
3057 // location: Code
3058 case 0x41:
3059 // kind: type in resource variable declaration
3060 // location: Code
3061
3062 {
3063 // struct:
3064 // localvar_target {
3065 // u2 table_length;
3066 // struct {
3067 // u2 start_pc;
3068 // u2 length;
3069 // u2 index;
3070 // } table[table_length];
3071 // }
3072 //
3073 if ((byte_i_ref + 2) > type_annotations_typeArray->length()) {
3074 // not enough room for a table_length let alone the rest of a localvar_target
3075 log_debug(redefine, class, annotation)("length() is too small for a localvar_target table_length");
3076 return false;
3077 }
3078
3079 u2 table_length = Bytes::get_Java_u2((address)
3080 type_annotations_typeArray->adr_at(byte_i_ref));
3081 byte_i_ref += 2;
3082
3083 log_debug(redefine, class, annotation)("localvar_target: table_length=%d", table_length);
3084
3085 int table_struct_size = 2 + 2 + 2; // 3 u2 variables per table entry
3086 int table_size = table_length * table_struct_size;
3087
3088 if ((byte_i_ref + table_size) > type_annotations_typeArray->length()) {
3089 // not enough room for a table
3090 log_debug(redefine, class, annotation)("length() is too small for a table array of length %d", table_length);
3091 return false;
3092 }
3093
3094 // Skip over table
3095 byte_i_ref += table_size;
3096 } break;
3097
3098 case 0x42:
3099 // kind: type in exception parameter declaration
3100 // location: Code
3101
3102 {
3103 // struct:
3104 // catch_target {
3105 // u2 exception_table_index;
3106 // }
3107 //
3108 if ((byte_i_ref + 2) > type_annotations_typeArray->length()) {
3109 log_debug(redefine, class, annotation)("length() is too small for a catch_target");
3110 return false;
3111 }
3112
3113 u2 exception_table_index = Bytes::get_Java_u2((address)
3114 type_annotations_typeArray->adr_at(byte_i_ref));
3115 byte_i_ref += 2;
3116
3117 log_debug(redefine, class, annotation)("catch_target: exception_table_index=%d", exception_table_index);
3118 } break;
3119
3120 case 0x43:
3121 // kind: type in instanceof expression
3122 // location: Code
3123 case 0x44:
3124 // kind: type in new expression
3125 // location: Code
3126 case 0x45:
3127 // kind: type in method reference expression using ::new
3128 // location: Code
3129 case 0x46:
3130 // kind: type in method reference expression using ::Identifier
3131 // location: Code
3132
3133 {
3134 // struct:
3135 // offset_target {
3136 // u2 offset;
3137 // }
3138 //
3139 if ((byte_i_ref + 2) > type_annotations_typeArray->length()) {
3140 log_debug(redefine, class, annotation)("length() is too small for a offset_target");
3141 return false;
3142 }
3143
3144 u2 offset = Bytes::get_Java_u2((address)
3145 type_annotations_typeArray->adr_at(byte_i_ref));
3146 byte_i_ref += 2;
3147
3148 log_debug(redefine, class, annotation)("offset_target: offset=%d", offset);
3149 } break;
3150
3151 case 0x47:
3152 // kind: type in cast expression
3153 // location: Code
3154 case 0x48:
3155 // kind: type argument for generic constructor in new expression or
3156 // explicit constructor invocation statement
3157 // location: Code
3158 case 0x49:
3159 // kind: type argument for generic method in method invocation expression
3160 // location: Code
3161 case 0x4A:
3162 // kind: type argument for generic constructor in method reference expression using ::new
3163 // location: Code
3164 case 0x4B:
3165 // kind: type argument for generic method in method reference expression using ::Identifier
3166 // location: Code
3167
3168 {
3169 // struct:
3170 // type_argument_target {
3171 // u2 offset;
3172 // u1 type_argument_index;
3173 // }
3174 //
3175 if ((byte_i_ref + 3) > type_annotations_typeArray->length()) {
3176 log_debug(redefine, class, annotation)("length() is too small for a type_argument_target");
3177 return false;
3178 }
3179
3180 u2 offset = Bytes::get_Java_u2((address)
3181 type_annotations_typeArray->adr_at(byte_i_ref));
3182 byte_i_ref += 2;
3183 u1 type_argument_index = type_annotations_typeArray->at(byte_i_ref);
3184 byte_i_ref += 1;
3185
3186 log_debug(redefine, class, annotation)
3187 ("type_argument_target: offset=%d, type_argument_index=%d", offset, type_argument_index);
3188 } break;
3189
3190 default:
3191 log_debug(redefine, class, annotation)("unknown target_type");
3192 #ifdef ASSERT
3193 ShouldNotReachHere();
3194 #endif
3195 return false;
3196 }
3197
3198 return true;
3199 } // end skip_type_annotation_target()
3200
3201
3202 // Read, verify and skip over the type_path part so that rewriting
3203 // can continue in the later parts of the struct.
3204 //
3205 // type_path {
3206 // u1 path_length;
3207 // {
3208 // u1 type_path_kind;
3209 // u1 type_argument_index;
3210 // } path[path_length];
3211 // }
3212 //
3213 bool VM_RedefineClasses::skip_type_annotation_type_path(
3214 AnnotationArray* type_annotations_typeArray, int &byte_i_ref) {
3215
3216 if ((byte_i_ref + 1) > type_annotations_typeArray->length()) {
3217 // not enough room for a path_length let alone the rest of the type_path
3218 log_debug(redefine, class, annotation)("length() is too small for a type_path");
3219 return false;
3220 }
3221
3222 u1 path_length = type_annotations_typeArray->at(byte_i_ref);
3223 byte_i_ref += 1;
3224
3225 log_debug(redefine, class, annotation)("type_path: path_length=%d", path_length);
3226
3227 int calc_path_length = 0;
3228 for (; calc_path_length < path_length; calc_path_length++) {
3229 if ((byte_i_ref + 1 + 1) > type_annotations_typeArray->length()) {
3230 // not enough room for a path
3231 log_debug(redefine, class, annotation)
3232 ("length() is too small for path entry %d of %d", calc_path_length, path_length);
3233 return false;
3234 }
3235
3236 u1 type_path_kind = type_annotations_typeArray->at(byte_i_ref);
3237 byte_i_ref += 1;
3238 u1 type_argument_index = type_annotations_typeArray->at(byte_i_ref);
3239 byte_i_ref += 1;
3240
3241 log_debug(redefine, class, annotation)
3242 ("type_path: path[%d]: type_path_kind=%d, type_argument_index=%d",
3243 calc_path_length, type_path_kind, type_argument_index);
3244
3245 if (type_path_kind > 3 || (type_path_kind != 3 && type_argument_index != 0)) {
3246 // not enough room for a path
3247 log_debug(redefine, class, annotation)("inconsistent type_path values");
3248 return false;
3249 }
3250 }
3251 assert(path_length == calc_path_length, "sanity check");
3252
3253 return true;
3254 } // end skip_type_annotation_type_path()
3255
3256
3257 // Rewrite constant pool references in the method's stackmap table.
3258 // These "structures" are adapted from the StackMapTable_attribute that
3259 // is described in section 4.8.4 of the 6.0 version of the VM spec
3260 // (dated 2005.10.26):
3261 // file:///net/quincunx.sfbay/export/gbracha/ClassFile-Java6.pdf
3262 //
3263 // stack_map {
3264 // u2 number_of_entries;
3265 // stack_map_frame entries[number_of_entries];
3266 // }
3267 //
3268 void VM_RedefineClasses::rewrite_cp_refs_in_stack_map_table(
3269 const methodHandle& method) {
3270
3271 if (!method->has_stackmap_table()) {
3272 return;
3273 }
3274
3275 AnnotationArray* stackmap_data = method->stackmap_data();
3276 address stackmap_p = (address)stackmap_data->adr_at(0);
3277 address stackmap_end = stackmap_p + stackmap_data->length();
3278
3279 assert(stackmap_p + 2 <= stackmap_end, "no room for number_of_entries");
3280 u2 number_of_entries = Bytes::get_Java_u2(stackmap_p);
3281 stackmap_p += 2;
3282
3283 log_debug(redefine, class, stackmap)("number_of_entries=%u", number_of_entries);
3284
3285 // walk through each stack_map_frame
3286 u2 calc_number_of_entries = 0;
3287 for (; calc_number_of_entries < number_of_entries; calc_number_of_entries++) {
3288 // The stack_map_frame structure is a u1 frame_type followed by
3289 // 0 or more bytes of data:
3290 //
3291 // union stack_map_frame {
3292 // same_frame;
3293 // same_locals_1_stack_item_frame;
3294 // same_locals_1_stack_item_frame_extended;
3295 // chop_frame;
3296 // same_frame_extended;
3297 // append_frame;
3298 // full_frame;
3299 // }
3300
3301 assert(stackmap_p + 1 <= stackmap_end, "no room for frame_type");
3302 u1 frame_type = *stackmap_p;
3303 stackmap_p++;
3304
3305 // same_frame {
3306 // u1 frame_type = SAME; /* 0-63 */
3307 // }
3308 if (frame_type <= 63) {
3309 // nothing more to do for same_frame
3310 }
3311
3312 // same_locals_1_stack_item_frame {
3313 // u1 frame_type = SAME_LOCALS_1_STACK_ITEM; /* 64-127 */
3314 // verification_type_info stack[1];
3315 // }
3316 else if (frame_type >= 64 && frame_type <= 127) {
3317 rewrite_cp_refs_in_verification_type_info(stackmap_p, stackmap_end,
3318 calc_number_of_entries, frame_type);
3319 }
3320
3321 // reserved for future use
3322 else if (frame_type >= 128 && frame_type <= 246) {
3323 // nothing more to do for reserved frame_types
3324 }
3325
3326 // same_locals_1_stack_item_frame_extended {
3327 // u1 frame_type = SAME_LOCALS_1_STACK_ITEM_EXTENDED; /* 247 */
3328 // u2 offset_delta;
3329 // verification_type_info stack[1];
3330 // }
3331 else if (frame_type == 247) {
3332 stackmap_p += 2;
3333 rewrite_cp_refs_in_verification_type_info(stackmap_p, stackmap_end,
3334 calc_number_of_entries, frame_type);
3335 }
3336
3337 // chop_frame {
3338 // u1 frame_type = CHOP; /* 248-250 */
3339 // u2 offset_delta;
3340 // }
3341 else if (frame_type >= 248 && frame_type <= 250) {
3342 stackmap_p += 2;
3343 }
3344
3345 // same_frame_extended {
3346 // u1 frame_type = SAME_FRAME_EXTENDED; /* 251*/
3347 // u2 offset_delta;
3348 // }
3349 else if (frame_type == 251) {
3350 stackmap_p += 2;
3351 }
3352
3353 // append_frame {
3354 // u1 frame_type = APPEND; /* 252-254 */
3355 // u2 offset_delta;
3356 // verification_type_info locals[frame_type - 251];
3357 // }
3358 else if (frame_type >= 252 && frame_type <= 254) {
3359 assert(stackmap_p + 2 <= stackmap_end,
3360 "no room for offset_delta");
3361 stackmap_p += 2;
3362 u1 len = frame_type - 251;
3363 for (u1 i = 0; i < len; i++) {
3364 rewrite_cp_refs_in_verification_type_info(stackmap_p, stackmap_end,
3365 calc_number_of_entries, frame_type);
3366 }
3367 }
3368
3369 // full_frame {
3370 // u1 frame_type = FULL_FRAME; /* 255 */
3371 // u2 offset_delta;
3372 // u2 number_of_locals;
3373 // verification_type_info locals[number_of_locals];
3374 // u2 number_of_stack_items;
3375 // verification_type_info stack[number_of_stack_items];
3376 // }
3377 else if (frame_type == 255) {
3378 assert(stackmap_p + 2 + 2 <= stackmap_end,
3379 "no room for smallest full_frame");
3380 stackmap_p += 2;
3381
3382 u2 number_of_locals = Bytes::get_Java_u2(stackmap_p);
3383 stackmap_p += 2;
3384
3385 for (u2 locals_i = 0; locals_i < number_of_locals; locals_i++) {
3386 rewrite_cp_refs_in_verification_type_info(stackmap_p, stackmap_end,
3387 calc_number_of_entries, frame_type);
3388 }
3389
3390 // Use the largest size for the number_of_stack_items, but only get
3391 // the right number of bytes.
3392 u2 number_of_stack_items = Bytes::get_Java_u2(stackmap_p);
3393 stackmap_p += 2;
3394
3395 for (u2 stack_i = 0; stack_i < number_of_stack_items; stack_i++) {
3396 rewrite_cp_refs_in_verification_type_info(stackmap_p, stackmap_end,
3397 calc_number_of_entries, frame_type);
3398 }
3399 }
3400 } // end while there is a stack_map_frame
3401 assert(number_of_entries == calc_number_of_entries, "sanity check");
3402 } // end rewrite_cp_refs_in_stack_map_table()
3403
3404
3405 // Rewrite constant pool references in the verification type info
3406 // portion of the method's stackmap table. These "structures" are
3407 // adapted from the StackMapTable_attribute that is described in
3408 // section 4.8.4 of the 6.0 version of the VM spec (dated 2005.10.26):
3409 // file:///net/quincunx.sfbay/export/gbracha/ClassFile-Java6.pdf
3410 //
3411 // The verification_type_info structure is a u1 tag followed by 0 or
3412 // more bytes of data:
3413 //
3414 // union verification_type_info {
3415 // Top_variable_info;
3416 // Integer_variable_info;
3417 // Float_variable_info;
3418 // Long_variable_info;
3419 // Double_variable_info;
3420 // Null_variable_info;
3421 // UninitializedThis_variable_info;
3422 // Object_variable_info;
3423 // Uninitialized_variable_info;
3424 // }
3425 //
3426 void VM_RedefineClasses::rewrite_cp_refs_in_verification_type_info(
3427 address& stackmap_p_ref, address stackmap_end, u2 frame_i,
3428 u1 frame_type) {
3429
3430 assert(stackmap_p_ref + 1 <= stackmap_end, "no room for tag");
3431 u1 tag = *stackmap_p_ref;
3432 stackmap_p_ref++;
3433
3434 switch (tag) {
3435 // Top_variable_info {
3436 // u1 tag = ITEM_Top; /* 0 */
3437 // }
3438 // verificationType.hpp has zero as ITEM_Bogus instead of ITEM_Top
3439 case 0: // fall through
3440
3441 // Integer_variable_info {
3442 // u1 tag = ITEM_Integer; /* 1 */
3443 // }
3444 case ITEM_Integer: // fall through
3445
3446 // Float_variable_info {
3447 // u1 tag = ITEM_Float; /* 2 */
3448 // }
3449 case ITEM_Float: // fall through
3450
3451 // Double_variable_info {
3452 // u1 tag = ITEM_Double; /* 3 */
3453 // }
3454 case ITEM_Double: // fall through
3455
3456 // Long_variable_info {
3457 // u1 tag = ITEM_Long; /* 4 */
3458 // }
3459 case ITEM_Long: // fall through
3460
3461 // Null_variable_info {
3462 // u1 tag = ITEM_Null; /* 5 */
3463 // }
3464 case ITEM_Null: // fall through
3465
3466 // UninitializedThis_variable_info {
3467 // u1 tag = ITEM_UninitializedThis; /* 6 */
3468 // }
3469 case ITEM_UninitializedThis:
3470 // nothing more to do for the above tag types
3471 break;
3472
3473 // Object_variable_info {
3474 // u1 tag = ITEM_Object; /* 7 */
3475 // u2 cpool_index;
3476 // }
3477 case ITEM_Object:
3478 {
3479 assert(stackmap_p_ref + 2 <= stackmap_end, "no room for cpool_index");
3480 u2 cpool_index = Bytes::get_Java_u2(stackmap_p_ref);
3481 u2 new_cp_index = find_new_index(cpool_index);
3482 if (new_cp_index != 0) {
3483 log_debug(redefine, class, stackmap)("mapped old cpool_index=%d", cpool_index);
3484 Bytes::put_Java_u2(stackmap_p_ref, new_cp_index);
3485 cpool_index = new_cp_index;
3486 }
3487 stackmap_p_ref += 2;
3488
3489 log_debug(redefine, class, stackmap)
3490 ("frame_i=%u, frame_type=%u, cpool_index=%d", frame_i, frame_type, cpool_index);
3491 } break;
3492
3493 // Uninitialized_variable_info {
3494 // u1 tag = ITEM_Uninitialized; /* 8 */
3495 // u2 offset;
3496 // }
3497 case ITEM_Uninitialized:
3498 assert(stackmap_p_ref + 2 <= stackmap_end, "no room for offset");
3499 stackmap_p_ref += 2;
3500 break;
3501
3502 default:
3503 log_debug(redefine, class, stackmap)("frame_i=%u, frame_type=%u, bad tag=0x%x", frame_i, frame_type, tag);
3504 ShouldNotReachHere();
3505 break;
3506 } // end switch (tag)
3507 } // end rewrite_cp_refs_in_verification_type_info()
3508
3509
3510 // Change the constant pool associated with klass scratch_class to
3511 // scratch_cp. If shrink is true, then scratch_cp_length elements
3512 // are copied from scratch_cp to a smaller constant pool and the
3513 // smaller constant pool is associated with scratch_class.
3514 void VM_RedefineClasses::set_new_constant_pool(
3515 ClassLoaderData* loader_data,
3516 InstanceKlass* scratch_class, constantPoolHandle scratch_cp,
3517 int scratch_cp_length, TRAPS) {
3518 assert(scratch_cp->length() >= scratch_cp_length, "sanity check");
3519
3520 // scratch_cp is a merged constant pool and has enough space for a
3521 // worst case merge situation. We want to associate the minimum
3522 // sized constant pool with the klass to save space.
3523 ConstantPool* cp = ConstantPool::allocate(loader_data, scratch_cp_length, CHECK);
3524 constantPoolHandle smaller_cp(THREAD, cp);
3525
3526 // preserve version() value in the smaller copy
3527 int version = scratch_cp->version();
3528 assert(version != 0, "sanity check");
3529 smaller_cp->set_version(version);
3530
3531 // attach klass to new constant pool
3532 // reference to the cp holder is needed for copy_operands()
3533 smaller_cp->set_pool_holder(scratch_class);
3534
3535 smaller_cp->copy_fields(scratch_cp());
3536
3537 scratch_cp->copy_cp_to(1, scratch_cp_length - 1, smaller_cp, 1, THREAD);
3538 if (HAS_PENDING_EXCEPTION) {
3539 // Exception is handled in the caller
3540 loader_data->add_to_deallocate_list(smaller_cp());
3541 return;
3542 }
3543 scratch_cp = smaller_cp;
3544
3545 // attach new constant pool to klass
3546 scratch_class->set_constants(scratch_cp());
3547 scratch_cp->initialize_unresolved_klasses(loader_data, CHECK);
3548
3549 int i; // for portability
3550
3551 // update each field in klass to use new constant pool indices as needed
3552 for (JavaFieldStream fs(scratch_class); !fs.done(); fs.next()) {
3553 jshort cur_index = fs.name_index();
3554 jshort new_index = find_new_index(cur_index);
3555 if (new_index != 0) {
3556 log_trace(redefine, class, constantpool)("field-name_index change: %d to %d", cur_index, new_index);
3557 fs.set_name_index(new_index);
3558 }
3559 cur_index = fs.signature_index();
3560 new_index = find_new_index(cur_index);
3561 if (new_index != 0) {
3562 log_trace(redefine, class, constantpool)("field-signature_index change: %d to %d", cur_index, new_index);
3563 fs.set_signature_index(new_index);
3564 }
3565 cur_index = fs.initval_index();
3566 new_index = find_new_index(cur_index);
3567 if (new_index != 0) {
3568 log_trace(redefine, class, constantpool)("field-initval_index change: %d to %d", cur_index, new_index);
3569 fs.set_initval_index(new_index);
3570 }
3571 cur_index = fs.generic_signature_index();
3572 new_index = find_new_index(cur_index);
3573 if (new_index != 0) {
3574 log_trace(redefine, class, constantpool)("field-generic_signature change: %d to %d", cur_index, new_index);
3575 fs.set_generic_signature_index(new_index);
3576 }
3577 } // end for each field
3578
3579 // Update constant pool indices in the inner classes info to use
3580 // new constant indices as needed. The inner classes info is a
3581 // quadruple:
3582 // (inner_class_info, outer_class_info, inner_name, inner_access_flags)
3583 InnerClassesIterator iter(scratch_class);
3584 for (; !iter.done(); iter.next()) {
3585 int cur_index = iter.inner_class_info_index();
3586 if (cur_index == 0) {
3587 continue; // JVM spec. allows null inner class refs so skip it
3588 }
3589 int new_index = find_new_index(cur_index);
3590 if (new_index != 0) {
3591 log_trace(redefine, class, constantpool)("inner_class_info change: %d to %d", cur_index, new_index);
3592 iter.set_inner_class_info_index(new_index);
3593 }
3594 cur_index = iter.outer_class_info_index();
3595 new_index = find_new_index(cur_index);
3596 if (new_index != 0) {
3597 log_trace(redefine, class, constantpool)("outer_class_info change: %d to %d", cur_index, new_index);
3598 iter.set_outer_class_info_index(new_index);
3599 }
3600 cur_index = iter.inner_name_index();
3601 new_index = find_new_index(cur_index);
3602 if (new_index != 0) {
3603 log_trace(redefine, class, constantpool)("inner_name change: %d to %d", cur_index, new_index);
3604 iter.set_inner_name_index(new_index);
3605 }
3606 } // end for each inner class
3607
3608 // Attach each method in klass to the new constant pool and update
3609 // to use new constant pool indices as needed:
3610 Array<Method*>* methods = scratch_class->methods();
3611 for (i = methods->length() - 1; i >= 0; i--) {
3612 methodHandle method(THREAD, methods->at(i));
3613 method->set_constants(scratch_cp());
3614
3615 int new_index = find_new_index(method->name_index());
3616 if (new_index != 0) {
3617 log_trace(redefine, class, constantpool)
3618 ("method-name_index change: %d to %d", method->name_index(), new_index);
3619 method->set_name_index(new_index);
3620 }
3621 new_index = find_new_index(method->signature_index());
3622 if (new_index != 0) {
3623 log_trace(redefine, class, constantpool)
3624 ("method-signature_index change: %d to %d", method->signature_index(), new_index);
3625 method->set_signature_index(new_index);
3626 }
3627 new_index = find_new_index(method->generic_signature_index());
3628 if (new_index != 0) {
3629 log_trace(redefine, class, constantpool)
3630 ("method-generic_signature_index change: %d to %d", method->generic_signature_index(), new_index);
3631 method->set_generic_signature_index(new_index);
3632 }
3633
3634 // Update constant pool indices in the method's checked exception
3635 // table to use new constant indices as needed.
3636 int cext_length = method->checked_exceptions_length();
3637 if (cext_length > 0) {
3638 CheckedExceptionElement * cext_table =
3639 method->checked_exceptions_start();
3640 for (int j = 0; j < cext_length; j++) {
3641 int cur_index = cext_table[j].class_cp_index;
3642 int new_index = find_new_index(cur_index);
3643 if (new_index != 0) {
3644 log_trace(redefine, class, constantpool)("cext-class_cp_index change: %d to %d", cur_index, new_index);
3645 cext_table[j].class_cp_index = (u2)new_index;
3646 }
3647 } // end for each checked exception table entry
3648 } // end if there are checked exception table entries
3649
3650 // Update each catch type index in the method's exception table
3651 // to use new constant pool indices as needed. The exception table
3652 // holds quadruple entries of the form:
3653 // (beg_bci, end_bci, handler_bci, klass_index)
3654
3655 ExceptionTable ex_table(method());
3656 int ext_length = ex_table.length();
3657
3658 for (int j = 0; j < ext_length; j ++) {
3659 int cur_index = ex_table.catch_type_index(j);
3660 int new_index = find_new_index(cur_index);
3661 if (new_index != 0) {
3662 log_trace(redefine, class, constantpool)("ext-klass_index change: %d to %d", cur_index, new_index);
3663 ex_table.set_catch_type_index(j, new_index);
3664 }
3665 } // end for each exception table entry
3666
3667 // Update constant pool indices in the method's local variable
3668 // table to use new constant indices as needed. The local variable
3669 // table hold sextuple entries of the form:
3670 // (start_pc, length, name_index, descriptor_index, signature_index, slot)
3671 int lvt_length = method->localvariable_table_length();
3672 if (lvt_length > 0) {
3673 LocalVariableTableElement * lv_table =
3674 method->localvariable_table_start();
3675 for (int j = 0; j < lvt_length; j++) {
3676 int cur_index = lv_table[j].name_cp_index;
3677 int new_index = find_new_index(cur_index);
3678 if (new_index != 0) {
3679 log_trace(redefine, class, constantpool)("lvt-name_cp_index change: %d to %d", cur_index, new_index);
3680 lv_table[j].name_cp_index = (u2)new_index;
3681 }
3682 cur_index = lv_table[j].descriptor_cp_index;
3683 new_index = find_new_index(cur_index);
3684 if (new_index != 0) {
3685 log_trace(redefine, class, constantpool)("lvt-descriptor_cp_index change: %d to %d", cur_index, new_index);
3686 lv_table[j].descriptor_cp_index = (u2)new_index;
3687 }
3688 cur_index = lv_table[j].signature_cp_index;
3689 new_index = find_new_index(cur_index);
3690 if (new_index != 0) {
3691 log_trace(redefine, class, constantpool)("lvt-signature_cp_index change: %d to %d", cur_index, new_index);
3692 lv_table[j].signature_cp_index = (u2)new_index;
3693 }
3694 } // end for each local variable table entry
3695 } // end if there are local variable table entries
3696
3697 rewrite_cp_refs_in_stack_map_table(method);
3698 } // end for each method
3699 } // end set_new_constant_pool()
3700
3701
3702 // Unevolving classes may point to methods of the_class directly
3703 // from their constant pool caches, itables, and/or vtables. We
3704 // use the ClassLoaderDataGraph::classes_do() facility and this helper
3705 // to fix up these pointers. MethodData also points to old methods and
3706 // must be cleaned.
3707
3708 // Adjust cpools and vtables closure
3709 void VM_RedefineClasses::AdjustAndCleanMetadata::do_klass(Klass* k) {
3710
3711 // This is a very busy routine. We don't want too much tracing
3712 // printed out.
3713 bool trace_name_printed = false;
3714
3715 // If the class being redefined is java.lang.Object, we need to fix all
3716 // array class vtables also. The _has_redefined_Object flag is global.
3717 // Once the java.lang.Object has been redefined (by the current or one
3718 // of the previous VM_RedefineClasses operations) we have to always
3719 // adjust method entries for array classes.
3720 if (k->is_array_klass() && _has_redefined_Object) {
3721 k->vtable().adjust_method_entries(&trace_name_printed);
3722
3723 } else if (k->is_instance_klass()) {
3724 HandleMark hm(_thread);
3725 InstanceKlass *ik = InstanceKlass::cast(k);
3726
3727 // Clean MethodData of this class's methods so they don't refer to
3728 // old methods that are no longer running.
3729 Array<Method*>* methods = ik->methods();
3730 int num_methods = methods->length();
3731 for (int index = 0; index < num_methods; ++index) {
3732 if (methods->at(index)->method_data() != NULL) {
3733 methods->at(index)->method_data()->clean_weak_method_links();
3734 }
3735 }
3736
3737 // Adjust all vtables, default methods and itables, to clean out old methods.
3738 ResourceMark rm(_thread);
3739 if (ik->vtable_length() > 0) {
3740 ik->vtable().adjust_method_entries(&trace_name_printed);
3741 ik->adjust_default_methods(&trace_name_printed);
3742 }
3743
3744 if (ik->itable_length() > 0) {
3745 ik->itable().adjust_method_entries(&trace_name_printed);
3746 }
3747
3748 // The constant pools in other classes (other_cp) can refer to
3749 // old methods. We have to update method information in
3750 // other_cp's cache. If other_cp has a previous version, then we
3751 // have to repeat the process for each previous version. The
3752 // constant pool cache holds the Method*s for non-virtual
3753 // methods and for virtual, final methods.
3754 //
3755 // Special case: if the current class is being redefined by the current
3756 // VM_RedefineClasses operation, then new_cp has already been attached
3757 // to the_class and old_cp has already been added as a previous version.
3758 // The new_cp doesn't have any cached references to old methods so it
3759 // doesn't need to be updated and we could optimize by skipping it.
3760 // However, the current class can be marked as being redefined by another
3761 // VM_RedefineClasses operation which has already executed its doit_prologue
3762 // and needs cpcache method entries adjusted. For simplicity, the cpcache
3763 // update is done unconditionally. It should result in doing nothing for
3764 // classes being redefined by the current VM_RedefineClasses operation.
3765 // Method entries in the previous version(s) are adjusted as well.
3766 ConstantPoolCache* cp_cache;
3767
3768 // this klass' constant pool cache may need adjustment
3769 ConstantPool* other_cp = ik->constants();
3770 cp_cache = other_cp->cache();
3771 if (cp_cache != NULL) {
3772 cp_cache->adjust_method_entries(&trace_name_printed);
3773 }
3774
3775 // the previous versions' constant pool caches may need adjustment
3776 for (InstanceKlass* pv_node = ik->previous_versions();
3777 pv_node != NULL;
3778 pv_node = pv_node->previous_versions()) {
3779 cp_cache = pv_node->constants()->cache();
3780 if (cp_cache != NULL) {
3781 cp_cache->adjust_method_entries(&trace_name_printed);
3782 }
3783 }
3784 }
3785 }
3786
3787 void VM_RedefineClasses::update_jmethod_ids() {
3788 for (int j = 0; j < _matching_methods_length; ++j) {
3789 Method* old_method = _matching_old_methods[j];
3790 jmethodID jmid = old_method->find_jmethod_id_or_null();
3791 if (jmid != NULL) {
3792 // There is a jmethodID, change it to point to the new method
3793 Method* new_method = _matching_new_methods[j];
3794 Method::change_method_associated_with_jmethod_id(jmid, new_method);
3795 assert(Method::resolve_jmethod_id(jmid) == _matching_new_methods[j],
3796 "should be replaced");
3797 }
3798 }
3799 }
3800
3801 int VM_RedefineClasses::check_methods_and_mark_as_obsolete() {
3802 int emcp_method_count = 0;
3803 int obsolete_count = 0;
3804 int old_index = 0;
3805 for (int j = 0; j < _matching_methods_length; ++j, ++old_index) {
3806 Method* old_method = _matching_old_methods[j];
3807 Method* new_method = _matching_new_methods[j];
3808 Method* old_array_method;
3809
3810 // Maintain an old_index into the _old_methods array by skipping
3811 // deleted methods
3812 while ((old_array_method = _old_methods->at(old_index)) != old_method) {
3813 ++old_index;
3814 }
3815
3816 if (MethodComparator::methods_EMCP(old_method, new_method)) {
3817 // The EMCP definition from JSR-163 requires the bytecodes to be
3818 // the same with the exception of constant pool indices which may
3819 // differ. However, the constants referred to by those indices
3820 // must be the same.
3821 //
3822 // We use methods_EMCP() for comparison since constant pool
3823 // merging can remove duplicate constant pool entries that were
3824 // present in the old method and removed from the rewritten new
3825 // method. A faster binary comparison function would consider the
3826 // old and new methods to be different when they are actually
3827 // EMCP.
3828 //
3829 // The old and new methods are EMCP and you would think that we
3830 // could get rid of one of them here and now and save some space.
3831 // However, the concept of EMCP only considers the bytecodes and
3832 // the constant pool entries in the comparison. Other things,
3833 // e.g., the line number table (LNT) or the local variable table
3834 // (LVT) don't count in the comparison. So the new (and EMCP)
3835 // method can have a new LNT that we need so we can't just
3836 // overwrite the new method with the old method.
3837 //
3838 // When this routine is called, we have already attached the new
3839 // methods to the_class so the old methods are effectively
3840 // overwritten. However, if an old method is still executing,
3841 // then the old method cannot be collected until sometime after
3842 // the old method call has returned. So the overwriting of old
3843 // methods by new methods will save us space except for those
3844 // (hopefully few) old methods that are still executing.
3845 //
3846 // A method refers to a ConstMethod* and this presents another
3847 // possible avenue to space savings. The ConstMethod* in the
3848 // new method contains possibly new attributes (LNT, LVT, etc).
3849 // At first glance, it seems possible to save space by replacing
3850 // the ConstMethod* in the old method with the ConstMethod*
3851 // from the new method. The old and new methods would share the
3852 // same ConstMethod* and we would save the space occupied by
3853 // the old ConstMethod*. However, the ConstMethod* contains
3854 // a back reference to the containing method. Sharing the
3855 // ConstMethod* between two methods could lead to confusion in
3856 // the code that uses the back reference. This would lead to
3857 // brittle code that could be broken in non-obvious ways now or
3858 // in the future.
3859 //
3860 // Another possibility is to copy the ConstMethod* from the new
3861 // method to the old method and then overwrite the new method with
3862 // the old method. Since the ConstMethod* contains the bytecodes
3863 // for the method embedded in the oop, this option would change
3864 // the bytecodes out from under any threads executing the old
3865 // method and make the thread's bcp invalid. Since EMCP requires
3866 // that the bytecodes be the same modulo constant pool indices, it
3867 // is straight forward to compute the correct new bcp in the new
3868 // ConstMethod* from the old bcp in the old ConstMethod*. The
3869 // time consuming part would be searching all the frames in all
3870 // of the threads to find all of the calls to the old method.
3871 //
3872 // It looks like we will have to live with the limited savings
3873 // that we get from effectively overwriting the old methods
3874 // when the new methods are attached to the_class.
3875
3876 // Count number of methods that are EMCP. The method will be marked
3877 // old but not obsolete if it is EMCP.
3878 emcp_method_count++;
3879
3880 // An EMCP method is _not_ obsolete. An obsolete method has a
3881 // different jmethodID than the current method. An EMCP method
3882 // has the same jmethodID as the current method. Having the
3883 // same jmethodID for all EMCP versions of a method allows for
3884 // a consistent view of the EMCP methods regardless of which
3885 // EMCP method you happen to have in hand. For example, a
3886 // breakpoint set in one EMCP method will work for all EMCP
3887 // versions of the method including the current one.
3888 } else {
3889 // mark obsolete methods as such
3890 old_method->set_is_obsolete();
3891 obsolete_count++;
3892
3893 // obsolete methods need a unique idnum so they become new entries in
3894 // the jmethodID cache in InstanceKlass
3895 assert(old_method->method_idnum() == new_method->method_idnum(), "must match");
3896 u2 num = InstanceKlass::cast(_the_class)->next_method_idnum();
3897 if (num != ConstMethod::UNSET_IDNUM) {
3898 old_method->set_method_idnum(num);
3899 }
3900
3901 // With tracing we try not to "yack" too much. The position of
3902 // this trace assumes there are fewer obsolete methods than
3903 // EMCP methods.
3904 if (log_is_enabled(Trace, redefine, class, obsolete, mark)) {
3905 ResourceMark rm;
3906 log_trace(redefine, class, obsolete, mark)
3907 ("mark %s(%s) as obsolete", old_method->name()->as_C_string(), old_method->signature()->as_C_string());
3908 }
3909 }
3910 old_method->set_is_old();
3911 }
3912 for (int i = 0; i < _deleted_methods_length; ++i) {
3913 Method* old_method = _deleted_methods[i];
3914
3915 assert(!old_method->has_vtable_index(),
3916 "cannot delete methods with vtable entries");;
3917
3918 // Mark all deleted methods as old, obsolete and deleted
3919 old_method->set_is_deleted();
3920 old_method->set_is_old();
3921 old_method->set_is_obsolete();
3922 ++obsolete_count;
3923 // With tracing we try not to "yack" too much. The position of
3924 // this trace assumes there are fewer obsolete methods than
3925 // EMCP methods.
3926 if (log_is_enabled(Trace, redefine, class, obsolete, mark)) {
3927 ResourceMark rm;
3928 log_trace(redefine, class, obsolete, mark)
3929 ("mark deleted %s(%s) as obsolete", old_method->name()->as_C_string(), old_method->signature()->as_C_string());
3930 }
3931 }
3932 assert((emcp_method_count + obsolete_count) == _old_methods->length(),
3933 "sanity check");
3934 log_trace(redefine, class, obsolete, mark)("EMCP_cnt=%d, obsolete_cnt=%d", emcp_method_count, obsolete_count);
3935 return emcp_method_count;
3936 }
3937
3938 // This internal class transfers the native function registration from old methods
3939 // to new methods. It is designed to handle both the simple case of unchanged
3940 // native methods and the complex cases of native method prefixes being added and/or
3941 // removed.
3942 // It expects only to be used during the VM_RedefineClasses op (a safepoint).
3943 //
3944 // This class is used after the new methods have been installed in "the_class".
3945 //
3946 // So, for example, the following must be handled. Where 'm' is a method and
3947 // a number followed by an underscore is a prefix.
3948 //
3949 // Old Name New Name
3950 // Simple transfer to new method m -> m
3951 // Add prefix m -> 1_m
3952 // Remove prefix 1_m -> m
3953 // Simultaneous add of prefixes m -> 3_2_1_m
3954 // Simultaneous removal of prefixes 3_2_1_m -> m
3955 // Simultaneous add and remove 1_m -> 2_m
3956 // Same, caused by prefix removal only 3_2_1_m -> 3_2_m
3957 //
3958 class TransferNativeFunctionRegistration {
3959 private:
3960 InstanceKlass* the_class;
3961 int prefix_count;
3962 char** prefixes;
3963
3964 // Recursively search the binary tree of possibly prefixed method names.
3965 // Iteration could be used if all agents were well behaved. Full tree walk is
3966 // more resilent to agents not cleaning up intermediate methods.
3967 // Branch at each depth in the binary tree is:
3968 // (1) without the prefix.
3969 // (2) with the prefix.
3970 // where 'prefix' is the prefix at that 'depth' (first prefix, second prefix,...)
3971 Method* search_prefix_name_space(int depth, char* name_str, size_t name_len,
3972 Symbol* signature) {
3973 TempNewSymbol name_symbol = SymbolTable::probe(name_str, (int)name_len);
3974 if (name_symbol != NULL) {
3975 Method* method = the_class->lookup_method(name_symbol, signature);
3976 if (method != NULL) {
3977 // Even if prefixed, intermediate methods must exist.
3978 if (method->is_native()) {
3979 // Wahoo, we found a (possibly prefixed) version of the method, return it.
3980 return method;
3981 }
3982 if (depth < prefix_count) {
3983 // Try applying further prefixes (other than this one).
3984 method = search_prefix_name_space(depth+1, name_str, name_len, signature);
3985 if (method != NULL) {
3986 return method; // found
3987 }
3988
3989 // Try adding this prefix to the method name and see if it matches
3990 // another method name.
3991 char* prefix = prefixes[depth];
3992 size_t prefix_len = strlen(prefix);
3993 size_t trial_len = name_len + prefix_len;
3994 char* trial_name_str = NEW_RESOURCE_ARRAY(char, trial_len + 1);
3995 strcpy(trial_name_str, prefix);
3996 strcat(trial_name_str, name_str);
3997 method = search_prefix_name_space(depth+1, trial_name_str, trial_len,
3998 signature);
3999 if (method != NULL) {
4000 // If found along this branch, it was prefixed, mark as such
4001 method->set_is_prefixed_native();
4002 return method; // found
4003 }
4004 }
4005 }
4006 }
4007 return NULL; // This whole branch bore nothing
4008 }
4009
4010 // Return the method name with old prefixes stripped away.
4011 char* method_name_without_prefixes(Method* method) {
4012 Symbol* name = method->name();
4013 char* name_str = name->as_utf8();
4014
4015 // Old prefixing may be defunct, strip prefixes, if any.
4016 for (int i = prefix_count-1; i >= 0; i--) {
4017 char* prefix = prefixes[i];
4018 size_t prefix_len = strlen(prefix);
4019 if (strncmp(prefix, name_str, prefix_len) == 0) {
4020 name_str += prefix_len;
4021 }
4022 }
4023 return name_str;
4024 }
4025
4026 // Strip any prefixes off the old native method, then try to find a
4027 // (possibly prefixed) new native that matches it.
4028 Method* strip_and_search_for_new_native(Method* method) {
4029 ResourceMark rm;
4030 char* name_str = method_name_without_prefixes(method);
4031 return search_prefix_name_space(0, name_str, strlen(name_str),
4032 method->signature());
4033 }
4034
4035 public:
4036
4037 // Construct a native method transfer processor for this class.
4038 TransferNativeFunctionRegistration(InstanceKlass* _the_class) {
4039 assert(SafepointSynchronize::is_at_safepoint(), "sanity check");
4040
4041 the_class = _the_class;
4042 prefixes = JvmtiExport::get_all_native_method_prefixes(&prefix_count);
4043 }
4044
4045 // Attempt to transfer any of the old or deleted methods that are native
4046 void transfer_registrations(Method** old_methods, int methods_length) {
4047 for (int j = 0; j < methods_length; j++) {
4048 Method* old_method = old_methods[j];
4049
4050 if (old_method->is_native() && old_method->has_native_function()) {
4051 Method* new_method = strip_and_search_for_new_native(old_method);
4052 if (new_method != NULL) {
4053 // Actually set the native function in the new method.
4054 // Redefine does not send events (except CFLH), certainly not this
4055 // behind the scenes re-registration.
4056 new_method->set_native_function(old_method->native_function(),
4057 !Method::native_bind_event_is_interesting);
4058 }
4059 }
4060 }
4061 }
4062 };
4063
4064 // Don't lose the association between a native method and its JNI function.
4065 void VM_RedefineClasses::transfer_old_native_function_registrations(InstanceKlass* the_class) {
4066 TransferNativeFunctionRegistration transfer(the_class);
4067 transfer.transfer_registrations(_deleted_methods, _deleted_methods_length);
4068 transfer.transfer_registrations(_matching_old_methods, _matching_methods_length);
4069 }
4070
4071 // Deoptimize all compiled code that depends on the classes redefined.
4072 //
4073 // If the can_redefine_classes capability is obtained in the onload
4074 // phase then the compiler has recorded all dependencies from startup.
4075 // In that case we need only deoptimize and throw away all compiled code
4076 // that depends on the class.
4077 //
4078 // If can_redefine_classes is obtained sometime after the onload
4079 // phase then the dependency information may be incomplete. In that case
4080 // the first call to RedefineClasses causes all compiled code to be
4081 // thrown away. As can_redefine_classes has been obtained then
4082 // all future compilations will record dependencies so second and
4083 // subsequent calls to RedefineClasses need only throw away code
4084 // that depends on the class.
4085 //
4086
4087 void VM_RedefineClasses::flush_dependent_code() {
4088 assert(SafepointSynchronize::is_at_safepoint(), "sanity check");
4089
4090 bool deopt_needed;
4091
4092 // This is the first redefinition, mark all the nmethods for deoptimization
4093 if (!JvmtiExport::all_dependencies_are_recorded()) {
4094 log_debug(redefine, class, nmethod)("Marked all nmethods for deopt");
4095 CodeCache::mark_all_nmethods_for_evol_deoptimization();
4096 deopt_needed = true;
4097 } else {
4098 int deopt = CodeCache::mark_dependents_for_evol_deoptimization();
4099 log_debug(redefine, class, nmethod)("Marked %d dependent nmethods for deopt", deopt);
4100 deopt_needed = (deopt != 0);
4101 }
4102
4103 if (deopt_needed) {
4104 CodeCache::flush_evol_dependents();
4105 }
4106
4107 // From now on we know that the dependency information is complete
4108 JvmtiExport::set_all_dependencies_are_recorded(true);
4109 }
4110
4111 void VM_RedefineClasses::compute_added_deleted_matching_methods() {
4112 Method* old_method;
4113 Method* new_method;
4114
4115 _matching_old_methods = NEW_RESOURCE_ARRAY(Method*, _old_methods->length());
4116 _matching_new_methods = NEW_RESOURCE_ARRAY(Method*, _old_methods->length());
4117 _added_methods = NEW_RESOURCE_ARRAY(Method*, _new_methods->length());
4118 _deleted_methods = NEW_RESOURCE_ARRAY(Method*, _old_methods->length());
4119
4120 _matching_methods_length = 0;
4121 _deleted_methods_length = 0;
4122 _added_methods_length = 0;
4123
4124 int nj = 0;
4125 int oj = 0;
4126 while (true) {
4127 if (oj >= _old_methods->length()) {
4128 if (nj >= _new_methods->length()) {
4129 break; // we've looked at everything, done
4130 }
4131 // New method at the end
4132 new_method = _new_methods->at(nj);
4133 _added_methods[_added_methods_length++] = new_method;
4134 ++nj;
4135 } else if (nj >= _new_methods->length()) {
4136 // Old method, at the end, is deleted
4137 old_method = _old_methods->at(oj);
4138 _deleted_methods[_deleted_methods_length++] = old_method;
4139 ++oj;
4140 } else {
4141 old_method = _old_methods->at(oj);
4142 new_method = _new_methods->at(nj);
4143 if (old_method->name() == new_method->name()) {
4144 if (old_method->signature() == new_method->signature()) {
4145 _matching_old_methods[_matching_methods_length ] = old_method;
4146 _matching_new_methods[_matching_methods_length++] = new_method;
4147 ++nj;
4148 ++oj;
4149 } else {
4150 // added overloaded have already been moved to the end,
4151 // so this is a deleted overloaded method
4152 _deleted_methods[_deleted_methods_length++] = old_method;
4153 ++oj;
4154 }
4155 } else { // names don't match
4156 if (old_method->name()->fast_compare(new_method->name()) > 0) {
4157 // new method
4158 _added_methods[_added_methods_length++] = new_method;
4159 ++nj;
4160 } else {
4161 // deleted method
4162 _deleted_methods[_deleted_methods_length++] = old_method;
4163 ++oj;
4164 }
4165 }
4166 }
4167 }
4168 assert(_matching_methods_length + _deleted_methods_length == _old_methods->length(), "sanity");
4169 assert(_matching_methods_length + _added_methods_length == _new_methods->length(), "sanity");
4170 }
4171
4172
4173 void VM_RedefineClasses::swap_annotations(InstanceKlass* the_class,
4174 InstanceKlass* scratch_class) {
4175 // Swap annotation fields values
4176 Annotations* old_annotations = the_class->annotations();
4177 the_class->set_annotations(scratch_class->annotations());
4178 scratch_class->set_annotations(old_annotations);
4179 }
4180
4181
4182 // Install the redefinition of a class:
4183 // - house keeping (flushing breakpoints and caches, deoptimizing
4184 // dependent compiled code)
4185 // - replacing parts in the_class with parts from scratch_class
4186 // - adding a weak reference to track the obsolete but interesting
4187 // parts of the_class
4188 // - adjusting constant pool caches and vtables in other classes
4189 // that refer to methods in the_class. These adjustments use the
4190 // ClassLoaderDataGraph::classes_do() facility which only allows
4191 // a helper method to be specified. The interesting parameters
4192 // that we would like to pass to the helper method are saved in
4193 // static global fields in the VM operation.
4194 void VM_RedefineClasses::redefine_single_class(Thread* current, jclass the_jclass,
4195 InstanceKlass* scratch_class) {
4196
4197 HandleMark hm(current); // make sure handles from this call are freed
4198
4199 if (log_is_enabled(Info, redefine, class, timer)) {
4200 _timer_rsc_phase1.start();
4201 }
4202
4203 InstanceKlass* the_class = get_ik(the_jclass);
4204
4205 // Set a flag to control and optimize adjusting method entries
4206 _has_redefined_Object |= the_class == vmClasses::Object_klass();
4207
4208 // Remove all breakpoints in methods of this class
4209 JvmtiBreakpoints& jvmti_breakpoints = JvmtiCurrentBreakpoints::get_jvmti_breakpoints();
4210 jvmti_breakpoints.clearall_in_class_at_safepoint(the_class);
4211
4212 _old_methods = the_class->methods();
4213 _new_methods = scratch_class->methods();
4214 _the_class = the_class;
4215 compute_added_deleted_matching_methods();
4216 update_jmethod_ids();
4217
4218 _any_class_has_resolved_methods = the_class->has_resolved_methods() || _any_class_has_resolved_methods;
4219
4220 // Attach new constant pool to the original klass. The original
4221 // klass still refers to the old constant pool (for now).
4222 scratch_class->constants()->set_pool_holder(the_class);
4223
4224 #if 0
4225 // In theory, with constant pool merging in place we should be able
4226 // to save space by using the new, merged constant pool in place of
4227 // the old constant pool(s). By "pool(s)" I mean the constant pool in
4228 // the klass version we are replacing now and any constant pool(s) in
4229 // previous versions of klass. Nice theory, doesn't work in practice.
4230 // When this code is enabled, even simple programs throw NullPointer
4231 // exceptions. I'm guessing that this is caused by some constant pool
4232 // cache difference between the new, merged constant pool and the
4233 // constant pool that was just being used by the klass. I'm keeping
4234 // this code around to archive the idea, but the code has to remain
4235 // disabled for now.
4236
4237 // Attach each old method to the new constant pool. This can be
4238 // done here since we are past the bytecode verification and
4239 // constant pool optimization phases.
4240 for (int i = _old_methods->length() - 1; i >= 0; i--) {
4241 Method* method = _old_methods->at(i);
4242 method->set_constants(scratch_class->constants());
4243 }
4244
4245 // NOTE: this doesn't work because you can redefine the same class in two
4246 // threads, each getting their own constant pool data appended to the
4247 // original constant pool. In order for the new methods to work when they
4248 // become old methods, they need to keep their updated copy of the constant pool.
4249
4250 {
4251 // walk all previous versions of the klass
4252 InstanceKlass *ik = the_class;
4253 PreviousVersionWalker pvw(ik);
4254 do {
4255 ik = pvw.next_previous_version();
4256 if (ik != NULL) {
4257
4258 // attach previous version of klass to the new constant pool
4259 ik->set_constants(scratch_class->constants());
4260
4261 // Attach each method in the previous version of klass to the
4262 // new constant pool
4263 Array<Method*>* prev_methods = ik->methods();
4264 for (int i = prev_methods->length() - 1; i >= 0; i--) {
4265 Method* method = prev_methods->at(i);
4266 method->set_constants(scratch_class->constants());
4267 }
4268 }
4269 } while (ik != NULL);
4270 }
4271 #endif
4272
4273 // Replace methods and constantpool
4274 the_class->set_methods(_new_methods);
4275 scratch_class->set_methods(_old_methods); // To prevent potential GCing of the old methods,
4276 // and to be able to undo operation easily.
4277
4278 Array<int>* old_ordering = the_class->method_ordering();
4279 the_class->set_method_ordering(scratch_class->method_ordering());
4280 scratch_class->set_method_ordering(old_ordering);
4281
4282 ConstantPool* old_constants = the_class->constants();
4283 the_class->set_constants(scratch_class->constants());
4284 scratch_class->set_constants(old_constants); // See the previous comment.
4285 #if 0
4286 // We are swapping the guts of "the new class" with the guts of "the
4287 // class". Since the old constant pool has just been attached to "the
4288 // new class", it seems logical to set the pool holder in the old
4289 // constant pool also. However, doing this will change the observable
4290 // class hierarchy for any old methods that are still executing. A
4291 // method can query the identity of its "holder" and this query uses
4292 // the method's constant pool link to find the holder. The change in
4293 // holding class from "the class" to "the new class" can confuse
4294 // things.
4295 //
4296 // Setting the old constant pool's holder will also cause
4297 // verification done during vtable initialization below to fail.
4298 // During vtable initialization, the vtable's class is verified to be
4299 // a subtype of the method's holder. The vtable's class is "the
4300 // class" and the method's holder is gotten from the constant pool
4301 // link in the method itself. For "the class"'s directly implemented
4302 // methods, the method holder is "the class" itself (as gotten from
4303 // the new constant pool). The check works fine in this case. The
4304 // check also works fine for methods inherited from super classes.
4305 //
4306 // Miranda methods are a little more complicated. A miranda method is
4307 // provided by an interface when the class implementing the interface
4308 // does not provide its own method. These interfaces are implemented
4309 // internally as an InstanceKlass. These special instanceKlasses
4310 // share the constant pool of the class that "implements" the
4311 // interface. By sharing the constant pool, the method holder of a
4312 // miranda method is the class that "implements" the interface. In a
4313 // non-redefine situation, the subtype check works fine. However, if
4314 // the old constant pool's pool holder is modified, then the check
4315 // fails because there is no class hierarchy relationship between the
4316 // vtable's class and "the new class".
4317
4318 old_constants->set_pool_holder(scratch_class());
4319 #endif
4320
4321 // track number of methods that are EMCP for add_previous_version() call below
4322 int emcp_method_count = check_methods_and_mark_as_obsolete();
4323 transfer_old_native_function_registrations(the_class);
4324
4325 // The class file bytes from before any retransformable agents mucked
4326 // with them was cached on the scratch class, move to the_class.
4327 // Note: we still want to do this if nothing needed caching since it
4328 // should get cleared in the_class too.
4329 if (the_class->get_cached_class_file() == 0) {
4330 // the_class doesn't have a cache yet so copy it
4331 the_class->set_cached_class_file(scratch_class->get_cached_class_file());
4332 }
4333 else if (scratch_class->get_cached_class_file() !=
4334 the_class->get_cached_class_file()) {
4335 // The same class can be present twice in the scratch classes list or there
4336 // are multiple concurrent RetransformClasses calls on different threads.
4337 // In such cases we have to deallocate scratch_class cached_class_file.
4338 os::free(scratch_class->get_cached_class_file());
4339 }
4340
4341 // NULL out in scratch class to not delete twice. The class to be redefined
4342 // always owns these bytes.
4343 scratch_class->set_cached_class_file(NULL);
4344
4345 // Replace inner_classes
4346 Array<u2>* old_inner_classes = the_class->inner_classes();
4347 the_class->set_inner_classes(scratch_class->inner_classes());
4348 scratch_class->set_inner_classes(old_inner_classes);
4349
4350 // Initialize the vtable and interface table after
4351 // methods have been rewritten
4352 // no exception should happen here since we explicitly
4353 // do not check loader constraints.
4354 // compare_and_normalize_class_versions has already checked:
4355 // - classloaders unchanged, signatures unchanged
4356 // - all instanceKlasses for redefined classes reused & contents updated
4357 the_class->vtable().initialize_vtable();
4358 the_class->itable().initialize_itable();
4359
4360 // Leave arrays of jmethodIDs and itable index cache unchanged
4361
4362 // Copy the "source file name" attribute from new class version
4363 the_class->set_source_file_name_index(
4364 scratch_class->source_file_name_index());
4365
4366 // Copy the "source debug extension" attribute from new class version
4367 the_class->set_source_debug_extension(
4368 scratch_class->source_debug_extension(),
4369 scratch_class->source_debug_extension() == NULL ? 0 :
4370 (int)strlen(scratch_class->source_debug_extension()));
4371
4372 // Use of javac -g could be different in the old and the new
4373 if (scratch_class->access_flags().has_localvariable_table() !=
4374 the_class->access_flags().has_localvariable_table()) {
4375
4376 AccessFlags flags = the_class->access_flags();
4377 if (scratch_class->access_flags().has_localvariable_table()) {
4378 flags.set_has_localvariable_table();
4379 } else {
4380 flags.clear_has_localvariable_table();
4381 }
4382 the_class->set_access_flags(flags);
4383 }
4384
4385 swap_annotations(the_class, scratch_class);
4386
4387 // Replace minor version number of class file
4388 u2 old_minor_version = the_class->constants()->minor_version();
4389 the_class->constants()->set_minor_version(scratch_class->constants()->minor_version());
4390 scratch_class->constants()->set_minor_version(old_minor_version);
4391
4392 // Replace major version number of class file
4393 u2 old_major_version = the_class->constants()->major_version();
4394 the_class->constants()->set_major_version(scratch_class->constants()->major_version());
4395 scratch_class->constants()->set_major_version(old_major_version);
4396
4397 // Replace CP indexes for class and name+type of enclosing method
4398 u2 old_class_idx = the_class->enclosing_method_class_index();
4399 u2 old_method_idx = the_class->enclosing_method_method_index();
4400 the_class->set_enclosing_method_indices(
4401 scratch_class->enclosing_method_class_index(),
4402 scratch_class->enclosing_method_method_index());
4403 scratch_class->set_enclosing_method_indices(old_class_idx, old_method_idx);
4404
4405 the_class->set_has_been_redefined();
4406
4407 // keep track of previous versions of this class
4408 the_class->add_previous_version(scratch_class, emcp_method_count);
4409
4410 _timer_rsc_phase1.stop();
4411 if (log_is_enabled(Info, redefine, class, timer)) {
4412 _timer_rsc_phase2.start();
4413 }
4414
4415 if (the_class->oop_map_cache() != NULL) {
4416 // Flush references to any obsolete methods from the oop map cache
4417 // so that obsolete methods are not pinned.
4418 the_class->oop_map_cache()->flush_obsolete_entries();
4419 }
4420
4421 increment_class_counter(the_class);
4422
4423 if (EventClassRedefinition::is_enabled()) {
4424 EventClassRedefinition event;
4425 event.set_classModificationCount(java_lang_Class::classRedefinedCount(the_class->java_mirror()));
4426 event.set_redefinedClass(the_class);
4427 event.set_redefinitionId(_id);
4428 event.commit();
4429 }
4430
4431 {
4432 ResourceMark rm(current);
4433 // increment the classRedefinedCount field in the_class and in any
4434 // direct and indirect subclasses of the_class
4435 log_info(redefine, class, load)
4436 ("redefined name=%s, count=%d (avail_mem=" UINT64_FORMAT "K)",
4437 the_class->external_name(), java_lang_Class::classRedefinedCount(the_class->java_mirror()), os::available_memory() >> 10);
4438 Events::log_redefinition(current, "redefined class name=%s, count=%d",
4439 the_class->external_name(),
4440 java_lang_Class::classRedefinedCount(the_class->java_mirror()));
4441
4442 }
4443 _timer_rsc_phase2.stop();
4444
4445 } // end redefine_single_class()
4446
4447
4448 // Increment the classRedefinedCount field in the specific InstanceKlass
4449 // and in all direct and indirect subclasses.
4450 void VM_RedefineClasses::increment_class_counter(InstanceKlass* ik) {
4451 for (ClassHierarchyIterator iter(ik); !iter.done(); iter.next()) {
4452 // Only update instanceKlasses
4453 Klass* sub = iter.klass();
4454 if (sub->is_instance_klass()) {
4455 oop class_mirror = InstanceKlass::cast(sub)->java_mirror();
4456 Klass* class_oop = java_lang_Class::as_Klass(class_mirror);
4457 int new_count = java_lang_Class::classRedefinedCount(class_mirror) + 1;
4458 java_lang_Class::set_classRedefinedCount(class_mirror, new_count);
4459
4460 if (class_oop != _the_class) {
4461 // _the_class count is printed at end of redefine_single_class()
4462 log_debug(redefine, class, subclass)("updated count in subclass=%s to %d", ik->external_name(), new_count);
4463 }
4464 }
4465 }
4466 }
4467
4468 void VM_RedefineClasses::CheckClass::do_klass(Klass* k) {
4469 bool no_old_methods = true; // be optimistic
4470
4471 // Both array and instance classes have vtables.
4472 // a vtable should never contain old or obsolete methods
4473 ResourceMark rm(_thread);
4474 if (k->vtable_length() > 0 &&
4475 !k->vtable().check_no_old_or_obsolete_entries()) {
4476 if (log_is_enabled(Trace, redefine, class, obsolete, metadata)) {
4477 log_trace(redefine, class, obsolete, metadata)
4478 ("klassVtable::check_no_old_or_obsolete_entries failure -- OLD or OBSOLETE method found -- class: %s",
4479 k->signature_name());
4480 k->vtable().dump_vtable();
4481 }
4482 no_old_methods = false;
4483 }
4484
4485 if (k->is_instance_klass()) {
4486 HandleMark hm(_thread);
4487 InstanceKlass *ik = InstanceKlass::cast(k);
4488
4489 // an itable should never contain old or obsolete methods
4490 if (ik->itable_length() > 0 &&
4491 !ik->itable().check_no_old_or_obsolete_entries()) {
4492 if (log_is_enabled(Trace, redefine, class, obsolete, metadata)) {
4493 log_trace(redefine, class, obsolete, metadata)
4494 ("klassItable::check_no_old_or_obsolete_entries failure -- OLD or OBSOLETE method found -- class: %s",
4495 ik->signature_name());
4496 ik->itable().dump_itable();
4497 }
4498 no_old_methods = false;
4499 }
4500
4501 // the constant pool cache should never contain non-deleted old or obsolete methods
4502 if (ik->constants() != NULL &&
4503 ik->constants()->cache() != NULL &&
4504 !ik->constants()->cache()->check_no_old_or_obsolete_entries()) {
4505 if (log_is_enabled(Trace, redefine, class, obsolete, metadata)) {
4506 log_trace(redefine, class, obsolete, metadata)
4507 ("cp-cache::check_no_old_or_obsolete_entries failure -- OLD or OBSOLETE method found -- class: %s",
4508 ik->signature_name());
4509 ik->constants()->cache()->dump_cache();
4510 }
4511 no_old_methods = false;
4512 }
4513 }
4514
4515 // print and fail guarantee if old methods are found.
4516 if (!no_old_methods) {
4517 if (log_is_enabled(Trace, redefine, class, obsolete, metadata)) {
4518 dump_methods();
4519 } else {
4520 log_trace(redefine, class)("Use the '-Xlog:redefine+class*:' option "
4521 "to see more info about the following guarantee() failure.");
4522 }
4523 guarantee(false, "OLD and/or OBSOLETE method(s) found");
4524 }
4525 }
4526
4527 u8 VM_RedefineClasses::next_id() {
4528 while (true) {
4529 u8 id = _id_counter;
4530 u8 next_id = id + 1;
4531 u8 result = Atomic::cmpxchg(&_id_counter, id, next_id);
4532 if (result == id) {
4533 return next_id;
4534 }
4535 }
4536 }
4537
4538 void VM_RedefineClasses::dump_methods() {
4539 int j;
4540 log_trace(redefine, class, dump)("_old_methods --");
4541 for (j = 0; j < _old_methods->length(); ++j) {
4542 LogStreamHandle(Trace, redefine, class, dump) log_stream;
4543 Method* m = _old_methods->at(j);
4544 log_stream.print("%4d (%5d) ", j, m->vtable_index());
4545 m->access_flags().print_on(&log_stream);
4546 log_stream.print(" -- ");
4547 m->print_name(&log_stream);
4548 log_stream.cr();
4549 }
4550 log_trace(redefine, class, dump)("_new_methods --");
4551 for (j = 0; j < _new_methods->length(); ++j) {
4552 LogStreamHandle(Trace, redefine, class, dump) log_stream;
4553 Method* m = _new_methods->at(j);
4554 log_stream.print("%4d (%5d) ", j, m->vtable_index());
4555 m->access_flags().print_on(&log_stream);
4556 log_stream.print(" -- ");
4557 m->print_name(&log_stream);
4558 log_stream.cr();
4559 }
4560 log_trace(redefine, class, dump)("_matching_methods --");
4561 for (j = 0; j < _matching_methods_length; ++j) {
4562 LogStreamHandle(Trace, redefine, class, dump) log_stream;
4563 Method* m = _matching_old_methods[j];
4564 log_stream.print("%4d (%5d) ", j, m->vtable_index());
4565 m->access_flags().print_on(&log_stream);
4566 log_stream.print(" -- ");
4567 m->print_name();
4568 log_stream.cr();
4569
4570 m = _matching_new_methods[j];
4571 log_stream.print(" (%5d) ", m->vtable_index());
4572 m->access_flags().print_on(&log_stream);
4573 log_stream.cr();
4574 }
4575 log_trace(redefine, class, dump)("_deleted_methods --");
4576 for (j = 0; j < _deleted_methods_length; ++j) {
4577 LogStreamHandle(Trace, redefine, class, dump) log_stream;
4578 Method* m = _deleted_methods[j];
4579 log_stream.print("%4d (%5d) ", j, m->vtable_index());
4580 m->access_flags().print_on(&log_stream);
4581 log_stream.print(" -- ");
4582 m->print_name(&log_stream);
4583 log_stream.cr();
4584 }
4585 log_trace(redefine, class, dump)("_added_methods --");
4586 for (j = 0; j < _added_methods_length; ++j) {
4587 LogStreamHandle(Trace, redefine, class, dump) log_stream;
4588 Method* m = _added_methods[j];
4589 log_stream.print("%4d (%5d) ", j, m->vtable_index());
4590 m->access_flags().print_on(&log_stream);
4591 log_stream.print(" -- ");
4592 m->print_name(&log_stream);
4593 log_stream.cr();
4594 }
4595 }
4596
4597 void VM_RedefineClasses::print_on_error(outputStream* st) const {
4598 VM_Operation::print_on_error(st);
4599 if (_the_class != NULL) {
4600 ResourceMark rm;
4601 st->print_cr(", redefining class %s", _the_class->external_name());
4602 }
4603 }