1 /*
2 * Copyright (c) 2003, 2018, 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 "aot/aotLoader.hpp"
27 #include "classfile/classFileStream.hpp"
28 #include "classfile/metadataOnStackMark.hpp"
29 #include "classfile/systemDictionary.hpp"
30 #include "classfile/verifier.hpp"
31 #include "code/codeCache.hpp"
32 #include "compiler/compileBroker.hpp"
33 #include "interpreter/oopMapCache.hpp"
34 #include "interpreter/rewriter.hpp"
35 #include "logging/logStream.hpp"
36 #include "memory/metadataFactory.hpp"
37 #include "memory/metaspaceShared.hpp"
38 #include "memory/resourceArea.hpp"
39 #include "memory/universe.hpp"
40 #include "oops/fieldStreams.hpp"
41 #include "oops/klassVtable.hpp"
42 #include "oops/oop.inline.hpp"
43 #include "prims/jvmtiImpl.hpp"
44 #include "prims/jvmtiRedefineClasses.hpp"
45 #include "prims/jvmtiThreadState.inline.hpp"
46 #include "prims/resolvedMethodTable.hpp"
47 #include "prims/methodComparator.hpp"
48 #include "runtime/deoptimization.hpp"
49 #include "runtime/handles.inline.hpp"
50 #include "runtime/jniHandles.inline.hpp"
51 #include "runtime/relocator.hpp"
52 #include "runtime/safepointVerifiers.hpp"
53 #include "utilities/bitMap.inline.hpp"
54 #include "utilities/events.hpp"
55
56 Array<Method*>* VM_RedefineClasses::_old_methods = NULL;
57 Array<Method*>* VM_RedefineClasses::_new_methods = NULL;
58 Method** VM_RedefineClasses::_matching_old_methods = NULL;
59 Method** VM_RedefineClasses::_matching_new_methods = NULL;
60 Method** VM_RedefineClasses::_deleted_methods = NULL;
61 Method** VM_RedefineClasses::_added_methods = NULL;
62 int VM_RedefineClasses::_matching_methods_length = 0;
63 int VM_RedefineClasses::_deleted_methods_length = 0;
64 int VM_RedefineClasses::_added_methods_length = 0;
65 Klass* VM_RedefineClasses::_the_class = NULL;
66
67
68 VM_RedefineClasses::VM_RedefineClasses(jint class_count,
69 const jvmtiClassDefinition *class_defs,
70 JvmtiClassLoadKind class_load_kind) {
71 _class_count = class_count;
72 _class_defs = class_defs;
73 _class_load_kind = class_load_kind;
74 _any_class_has_resolved_methods = false;
75 _res = JVMTI_ERROR_NONE;
76 }
77
78 static inline InstanceKlass* get_ik(jclass def) {
79 oop mirror = JNIHandles::resolve_non_null(def);
80 return InstanceKlass::cast(java_lang_Class::as_Klass(mirror));
81 }
82
83 // If any of the classes are being redefined, wait
84 // Parallel constant pool merging leads to indeterminate constant pools.
85 void VM_RedefineClasses::lock_classes() {
86 MutexLocker ml(RedefineClasses_lock);
87 bool has_redefined;
88 do {
89 has_redefined = false;
90 // Go through classes each time until none are being redefined.
91 for (int i = 0; i < _class_count; i++) {
92 if (get_ik(_class_defs[i].klass)->is_being_redefined()) {
93 RedefineClasses_lock->wait();
94 has_redefined = true;
95 break; // for loop
96 }
97 }
98 } while (has_redefined);
99 for (int i = 0; i < _class_count; i++) {
100 get_ik(_class_defs[i].klass)->set_is_being_redefined(true);
101 }
102 RedefineClasses_lock->notify_all();
103 }
104
105 void VM_RedefineClasses::unlock_classes() {
106 MutexLocker ml(RedefineClasses_lock);
107 for (int i = 0; i < _class_count; i++) {
108 assert(get_ik(_class_defs[i].klass)->is_being_redefined(),
109 "should be being redefined to get here");
110 get_ik(_class_defs[i].klass)->set_is_being_redefined(false);
111 }
112 RedefineClasses_lock->notify_all();
113 }
114
115 bool VM_RedefineClasses::doit_prologue() {
116 if (_class_count == 0) {
117 _res = JVMTI_ERROR_NONE;
118 return false;
119 }
120 if (_class_defs == NULL) {
121 _res = JVMTI_ERROR_NULL_POINTER;
122 return false;
123 }
124 for (int i = 0; i < _class_count; i++) {
125 if (_class_defs[i].klass == NULL) {
126 _res = JVMTI_ERROR_INVALID_CLASS;
127 return false;
128 }
129 if (_class_defs[i].class_byte_count == 0) {
130 _res = JVMTI_ERROR_INVALID_CLASS_FORMAT;
131 return false;
132 }
133 if (_class_defs[i].class_bytes == NULL) {
134 _res = JVMTI_ERROR_NULL_POINTER;
135 return false;
136 }
137
138 oop mirror = JNIHandles::resolve_non_null(_class_defs[i].klass);
139 // classes for primitives and arrays and vm unsafe anonymous classes cannot be redefined
140 // check here so following code can assume these classes are InstanceKlass
141 if (!is_modifiable_class(mirror)) {
142 _res = JVMTI_ERROR_UNMODIFIABLE_CLASS;
143 return false;
144 }
145 }
146
147 // Start timer after all the sanity checks; not quite accurate, but
148 // better than adding a bunch of stop() calls.
149 if (log_is_enabled(Info, redefine, class, timer)) {
150 _timer_vm_op_prologue.start();
151 }
152
153 lock_classes();
154 // We first load new class versions in the prologue, because somewhere down the
155 // call chain it is required that the current thread is a Java thread.
156 _res = load_new_class_versions(Thread::current());
157 if (_res != JVMTI_ERROR_NONE) {
158 // free any successfully created classes, since none are redefined
159 for (int i = 0; i < _class_count; i++) {
160 if (_scratch_classes[i] != NULL) {
161 ClassLoaderData* cld = _scratch_classes[i]->class_loader_data();
162 // Free the memory for this class at class unloading time. Not before
163 // because CMS might think this is still live.
164 InstanceKlass* ik = get_ik(_class_defs[i].klass);
165 if (ik->get_cached_class_file() == _scratch_classes[i]->get_cached_class_file()) {
166 // Don't double-free cached_class_file copied from the original class if error.
167 _scratch_classes[i]->set_cached_class_file(NULL);
168 }
169 cld->add_to_deallocate_list(InstanceKlass::cast(_scratch_classes[i]));
170 }
171 }
172 // Free os::malloc allocated memory in load_new_class_version.
173 os::free(_scratch_classes);
174 _timer_vm_op_prologue.stop();
175 unlock_classes();
176 return false;
177 }
178
179 _timer_vm_op_prologue.stop();
180 return true;
181 }
182
183 void VM_RedefineClasses::doit() {
184 Thread *thread = Thread::current();
185
186 #if INCLUDE_CDS
187 if (UseSharedSpaces) {
188 // Sharing is enabled so we remap the shared readonly space to
189 // shared readwrite, private just in case we need to redefine
190 // a shared class. We do the remap during the doit() phase of
191 // the safepoint to be safer.
192 if (!MetaspaceShared::remap_shared_readonly_as_readwrite()) {
193 log_info(redefine, class, load)("failed to remap shared readonly space to readwrite, private");
194 _res = JVMTI_ERROR_INTERNAL;
195 return;
196 }
197 }
198 #endif
199
200 // Mark methods seen on stack and everywhere else so old methods are not
201 // cleaned up if they're on the stack.
202 MetadataOnStackMark md_on_stack(true);
203 HandleMark hm(thread); // make sure any handles created are deleted
204 // before the stack walk again.
205
206 for (int i = 0; i < _class_count; i++) {
207 redefine_single_class(_class_defs[i].klass, _scratch_classes[i], thread);
208 }
209
210 // Clean out MethodData pointing to old Method*
211 // Have to do this after all classes are redefined and all methods that
212 // are redefined are marked as old.
213 MethodDataCleaner clean_weak_method_links;
214 ClassLoaderDataGraph::classes_do(&clean_weak_method_links);
215
216 // JSR-292 support
217 if (_any_class_has_resolved_methods) {
218 bool trace_name_printed = false;
219 ResolvedMethodTable::adjust_method_entries(&trace_name_printed);
220 }
221
222 // Disable any dependent concurrent compilations
223 SystemDictionary::notice_modification();
224
225 // Set flag indicating that some invariants are no longer true.
226 // See jvmtiExport.hpp for detailed explanation.
227 JvmtiExport::set_has_redefined_a_class();
228
229 // check_class() is optionally called for product bits, but is
230 // always called for non-product bits.
231 #ifdef PRODUCT
232 if (log_is_enabled(Trace, redefine, class, obsolete, metadata)) {
233 #endif
234 log_trace(redefine, class, obsolete, metadata)("calling check_class");
235 CheckClass check_class(thread);
236 ClassLoaderDataGraph::classes_do(&check_class);
237 #ifdef PRODUCT
238 }
239 #endif
240
241 // Clean up any metadata now unreferenced while MetadataOnStackMark is set.
242 ClassLoaderDataGraph::clean_deallocate_lists(false);
243 }
244
245 void VM_RedefineClasses::doit_epilogue() {
246 unlock_classes();
247
248 // Free os::malloc allocated memory.
249 os::free(_scratch_classes);
250
251 // Reset the_class to null for error printing.
252 _the_class = NULL;
253
254 if (log_is_enabled(Info, redefine, class, timer)) {
255 // Used to have separate timers for "doit" and "all", but the timer
256 // overhead skewed the measurements.
257 julong doit_time = _timer_rsc_phase1.milliseconds() +
258 _timer_rsc_phase2.milliseconds();
259 julong all_time = _timer_vm_op_prologue.milliseconds() + doit_time;
260
261 log_info(redefine, class, timer)
262 ("vm_op: all=" JULONG_FORMAT " prologue=" JULONG_FORMAT " doit=" JULONG_FORMAT,
263 all_time, (julong)_timer_vm_op_prologue.milliseconds(), doit_time);
264 log_info(redefine, class, timer)
265 ("redefine_single_class: phase1=" JULONG_FORMAT " phase2=" JULONG_FORMAT,
266 (julong)_timer_rsc_phase1.milliseconds(), (julong)_timer_rsc_phase2.milliseconds());
267 }
268 }
269
270 bool VM_RedefineClasses::is_modifiable_class(oop klass_mirror) {
271 // classes for primitives cannot be redefined
272 if (java_lang_Class::is_primitive(klass_mirror)) {
273 return false;
274 }
275 Klass* k = java_lang_Class::as_Klass(klass_mirror);
276 // classes for arrays cannot be redefined
277 if (k == NULL || !k->is_instance_klass()) {
278 return false;
279 }
280
281 // Cannot redefine or retransform an unsafe anonymous class.
282 if (InstanceKlass::cast(k)->is_unsafe_anonymous()) {
283 return false;
284 }
285 return true;
286 }
287
288 // Append the current entry at scratch_i in scratch_cp to *merge_cp_p
289 // where the end of *merge_cp_p is specified by *merge_cp_length_p. For
290 // direct CP entries, there is just the current entry to append. For
291 // indirect and double-indirect CP entries, there are zero or more
292 // referenced CP entries along with the current entry to append.
293 // Indirect and double-indirect CP entries are handled by recursive
294 // calls to append_entry() as needed. The referenced CP entries are
295 // always appended to *merge_cp_p before the referee CP entry. These
296 // referenced CP entries may already exist in *merge_cp_p in which case
297 // there is nothing extra to append and only the current entry is
298 // appended.
299 void VM_RedefineClasses::append_entry(const constantPoolHandle& scratch_cp,
300 int scratch_i, constantPoolHandle *merge_cp_p, int *merge_cp_length_p,
301 TRAPS) {
302
303 // append is different depending on entry tag type
304 switch (scratch_cp->tag_at(scratch_i).value()) {
305
306 // The old verifier is implemented outside the VM. It loads classes,
307 // but does not resolve constant pool entries directly so we never
308 // see Class entries here with the old verifier. Similarly the old
309 // verifier does not like Class entries in the input constant pool.
310 // The split-verifier is implemented in the VM so it can optionally
311 // and directly resolve constant pool entries to load classes. The
312 // split-verifier can accept either Class entries or UnresolvedClass
313 // entries in the input constant pool. We revert the appended copy
314 // back to UnresolvedClass so that either verifier will be happy
315 // with the constant pool entry.
316 //
317 // this is an indirect CP entry so it needs special handling
318 case JVM_CONSTANT_Class:
319 case JVM_CONSTANT_UnresolvedClass:
320 {
321 int name_i = scratch_cp->klass_name_index_at(scratch_i);
322 int new_name_i = find_or_append_indirect_entry(scratch_cp, name_i, merge_cp_p,
323 merge_cp_length_p, THREAD);
324
325 if (new_name_i != name_i) {
326 log_trace(redefine, class, constantpool)
327 ("Class entry@%d name_index change: %d to %d",
328 *merge_cp_length_p, name_i, new_name_i);
329 }
330
331 (*merge_cp_p)->temp_unresolved_klass_at_put(*merge_cp_length_p, new_name_i);
332 if (scratch_i != *merge_cp_length_p) {
333 // The new entry in *merge_cp_p is at a different index than
334 // the new entry in scratch_cp so we need to map the index values.
335 map_index(scratch_cp, scratch_i, *merge_cp_length_p);
336 }
337 (*merge_cp_length_p)++;
338 } break;
339
340 // these are direct CP entries so they can be directly appended,
341 // but double and long take two constant pool entries
342 case JVM_CONSTANT_Double: // fall through
343 case JVM_CONSTANT_Long:
344 {
345 ConstantPool::copy_entry_to(scratch_cp, scratch_i, *merge_cp_p, *merge_cp_length_p,
346 THREAD);
347
348 if (scratch_i != *merge_cp_length_p) {
349 // The new entry in *merge_cp_p is at a different index than
350 // the new entry in scratch_cp so we need to map the index values.
351 map_index(scratch_cp, scratch_i, *merge_cp_length_p);
352 }
353 (*merge_cp_length_p) += 2;
354 } break;
355
356 // these are direct CP entries so they can be directly appended
357 case JVM_CONSTANT_Float: // fall through
358 case JVM_CONSTANT_Integer: // fall through
359 case JVM_CONSTANT_Utf8: // fall through
360
361 // This was an indirect CP entry, but it has been changed into
362 // Symbol*s so this entry can be directly appended.
363 case JVM_CONSTANT_String: // fall through
364 {
365 ConstantPool::copy_entry_to(scratch_cp, scratch_i, *merge_cp_p, *merge_cp_length_p,
366 THREAD);
367
368 if (scratch_i != *merge_cp_length_p) {
369 // The new entry in *merge_cp_p is at a different index than
370 // the new entry in scratch_cp so we need to map the index values.
371 map_index(scratch_cp, scratch_i, *merge_cp_length_p);
372 }
373 (*merge_cp_length_p)++;
374 } break;
375
376 // this is an indirect CP entry so it needs special handling
377 case JVM_CONSTANT_NameAndType:
378 {
379 int name_ref_i = scratch_cp->name_ref_index_at(scratch_i);
380 int new_name_ref_i = find_or_append_indirect_entry(scratch_cp, name_ref_i, merge_cp_p,
381 merge_cp_length_p, THREAD);
382
383 int signature_ref_i = scratch_cp->signature_ref_index_at(scratch_i);
384 int new_signature_ref_i = find_or_append_indirect_entry(scratch_cp, signature_ref_i,
385 merge_cp_p, merge_cp_length_p,
386 THREAD);
387
388 // If the referenced entries already exist in *merge_cp_p, then
389 // both new_name_ref_i and new_signature_ref_i will both be 0.
390 // In that case, all we are appending is the current entry.
391 if (new_name_ref_i != name_ref_i) {
392 log_trace(redefine, class, constantpool)
393 ("NameAndType entry@%d name_ref_index change: %d to %d",
394 *merge_cp_length_p, name_ref_i, new_name_ref_i);
395 }
396 if (new_signature_ref_i != signature_ref_i) {
397 log_trace(redefine, class, constantpool)
398 ("NameAndType entry@%d signature_ref_index change: %d to %d",
399 *merge_cp_length_p, signature_ref_i, new_signature_ref_i);
400 }
401
402 (*merge_cp_p)->name_and_type_at_put(*merge_cp_length_p,
403 new_name_ref_i, new_signature_ref_i);
404 if (scratch_i != *merge_cp_length_p) {
405 // The new entry in *merge_cp_p is at a different index than
406 // the new entry in scratch_cp so we need to map the index values.
407 map_index(scratch_cp, scratch_i, *merge_cp_length_p);
408 }
409 (*merge_cp_length_p)++;
410 } break;
411
412 // this is a double-indirect CP entry so it needs special handling
413 case JVM_CONSTANT_Fieldref: // fall through
414 case JVM_CONSTANT_InterfaceMethodref: // fall through
415 case JVM_CONSTANT_Methodref:
416 {
417 int klass_ref_i = scratch_cp->uncached_klass_ref_index_at(scratch_i);
418 int new_klass_ref_i = find_or_append_indirect_entry(scratch_cp, klass_ref_i,
419 merge_cp_p, merge_cp_length_p, THREAD);
420
421 int name_and_type_ref_i = scratch_cp->uncached_name_and_type_ref_index_at(scratch_i);
422 int new_name_and_type_ref_i = find_or_append_indirect_entry(scratch_cp, name_and_type_ref_i,
423 merge_cp_p, merge_cp_length_p, THREAD);
424
425 const char *entry_name = NULL;
426 switch (scratch_cp->tag_at(scratch_i).value()) {
427 case JVM_CONSTANT_Fieldref:
428 entry_name = "Fieldref";
429 (*merge_cp_p)->field_at_put(*merge_cp_length_p, new_klass_ref_i,
430 new_name_and_type_ref_i);
431 break;
432 case JVM_CONSTANT_InterfaceMethodref:
433 entry_name = "IFMethodref";
434 (*merge_cp_p)->interface_method_at_put(*merge_cp_length_p,
435 new_klass_ref_i, new_name_and_type_ref_i);
436 break;
437 case JVM_CONSTANT_Methodref:
438 entry_name = "Methodref";
439 (*merge_cp_p)->method_at_put(*merge_cp_length_p, new_klass_ref_i,
440 new_name_and_type_ref_i);
441 break;
442 default:
443 guarantee(false, "bad switch");
444 break;
445 }
446
447 if (klass_ref_i != new_klass_ref_i) {
448 log_trace(redefine, class, constantpool)
449 ("%s entry@%d class_index changed: %d to %d", entry_name, *merge_cp_length_p, klass_ref_i, new_klass_ref_i);
450 }
451 if (name_and_type_ref_i != new_name_and_type_ref_i) {
452 log_trace(redefine, class, constantpool)
453 ("%s entry@%d name_and_type_index changed: %d to %d",
454 entry_name, *merge_cp_length_p, name_and_type_ref_i, new_name_and_type_ref_i);
455 }
456
457 if (scratch_i != *merge_cp_length_p) {
458 // The new entry in *merge_cp_p is at a different index than
459 // the new entry in scratch_cp so we need to map the index values.
460 map_index(scratch_cp, scratch_i, *merge_cp_length_p);
461 }
462 (*merge_cp_length_p)++;
463 } break;
464
465 // this is an indirect CP entry so it needs special handling
466 case JVM_CONSTANT_MethodType:
467 {
468 int ref_i = scratch_cp->method_type_index_at(scratch_i);
469 int new_ref_i = find_or_append_indirect_entry(scratch_cp, ref_i, merge_cp_p,
470 merge_cp_length_p, THREAD);
471 if (new_ref_i != ref_i) {
472 log_trace(redefine, class, constantpool)
473 ("MethodType entry@%d ref_index change: %d to %d", *merge_cp_length_p, ref_i, new_ref_i);
474 }
475 (*merge_cp_p)->method_type_index_at_put(*merge_cp_length_p, new_ref_i);
476 if (scratch_i != *merge_cp_length_p) {
477 // The new entry in *merge_cp_p is at a different index than
478 // the new entry in scratch_cp so we need to map the index values.
479 map_index(scratch_cp, scratch_i, *merge_cp_length_p);
480 }
481 (*merge_cp_length_p)++;
482 } break;
483
484 // this is an indirect CP entry so it needs special handling
485 case JVM_CONSTANT_MethodHandle:
486 {
487 int ref_kind = scratch_cp->method_handle_ref_kind_at(scratch_i);
488 int ref_i = scratch_cp->method_handle_index_at(scratch_i);
489 int new_ref_i = find_or_append_indirect_entry(scratch_cp, ref_i, merge_cp_p,
490 merge_cp_length_p, THREAD);
491 if (new_ref_i != ref_i) {
492 log_trace(redefine, class, constantpool)
493 ("MethodHandle entry@%d ref_index change: %d to %d", *merge_cp_length_p, ref_i, new_ref_i);
494 }
495 (*merge_cp_p)->method_handle_index_at_put(*merge_cp_length_p, ref_kind, new_ref_i);
496 if (scratch_i != *merge_cp_length_p) {
497 // The new entry in *merge_cp_p is at a different index than
498 // the new entry in scratch_cp so we need to map the index values.
499 map_index(scratch_cp, scratch_i, *merge_cp_length_p);
500 }
501 (*merge_cp_length_p)++;
502 } break;
503
504 // this is an indirect CP entry so it needs special handling
505 case JVM_CONSTANT_Dynamic: // fall through
506 case JVM_CONSTANT_InvokeDynamic:
507 {
508 // Index of the bootstrap specifier in the operands array
509 int old_bs_i = scratch_cp->invoke_dynamic_bootstrap_specifier_index(scratch_i);
510 int new_bs_i = find_or_append_operand(scratch_cp, old_bs_i, merge_cp_p,
511 merge_cp_length_p, THREAD);
512 // The bootstrap method NameAndType_info index
513 int old_ref_i = scratch_cp->invoke_dynamic_name_and_type_ref_index_at(scratch_i);
514 int new_ref_i = find_or_append_indirect_entry(scratch_cp, old_ref_i, merge_cp_p,
515 merge_cp_length_p, THREAD);
516 if (new_bs_i != old_bs_i) {
517 log_trace(redefine, class, constantpool)
518 ("Dynamic entry@%d bootstrap_method_attr_index change: %d to %d",
519 *merge_cp_length_p, old_bs_i, new_bs_i);
520 }
521 if (new_ref_i != old_ref_i) {
522 log_trace(redefine, class, constantpool)
523 ("Dynamic entry@%d name_and_type_index change: %d to %d", *merge_cp_length_p, old_ref_i, new_ref_i);
524 }
525
526 if (scratch_cp->tag_at(scratch_i).is_dynamic_constant())
527 (*merge_cp_p)->dynamic_constant_at_put(*merge_cp_length_p, new_bs_i, new_ref_i);
528 else
529 (*merge_cp_p)->invoke_dynamic_at_put(*merge_cp_length_p, new_bs_i, new_ref_i);
530 if (scratch_i != *merge_cp_length_p) {
531 // The new entry in *merge_cp_p is at a different index than
532 // the new entry in scratch_cp so we need to map the index values.
533 map_index(scratch_cp, scratch_i, *merge_cp_length_p);
534 }
535 (*merge_cp_length_p)++;
536 } break;
537
538 // At this stage, Class or UnresolvedClass could be in scratch_cp, but not
539 // ClassIndex
540 case JVM_CONSTANT_ClassIndex: // fall through
541
542 // Invalid is used as the tag for the second constant pool entry
543 // occupied by JVM_CONSTANT_Double or JVM_CONSTANT_Long. It should
544 // not be seen by itself.
545 case JVM_CONSTANT_Invalid: // fall through
546
547 // At this stage, String could be here, but not StringIndex
548 case JVM_CONSTANT_StringIndex: // fall through
549
550 // At this stage JVM_CONSTANT_UnresolvedClassInError should not be
551 // here
552 case JVM_CONSTANT_UnresolvedClassInError: // fall through
553
554 default:
555 {
556 // leave a breadcrumb
557 jbyte bad_value = scratch_cp->tag_at(scratch_i).value();
558 ShouldNotReachHere();
559 } break;
560 } // end switch tag value
561 } // end append_entry()
562
563
564 int VM_RedefineClasses::find_or_append_indirect_entry(const constantPoolHandle& scratch_cp,
565 int ref_i, constantPoolHandle *merge_cp_p, int *merge_cp_length_p, TRAPS) {
566
567 int new_ref_i = ref_i;
568 bool match = (ref_i < *merge_cp_length_p) &&
569 scratch_cp->compare_entry_to(ref_i, *merge_cp_p, ref_i, THREAD);
570
571 if (!match) {
572 // forward reference in *merge_cp_p or not a direct match
573 int found_i = scratch_cp->find_matching_entry(ref_i, *merge_cp_p, THREAD);
574 if (found_i != 0) {
575 guarantee(found_i != ref_i, "compare_entry_to() and find_matching_entry() do not agree");
576 // Found a matching entry somewhere else in *merge_cp_p so just need a mapping entry.
577 new_ref_i = found_i;
578 map_index(scratch_cp, ref_i, found_i);
579 } else {
580 // no match found so we have to append this entry to *merge_cp_p
581 append_entry(scratch_cp, ref_i, merge_cp_p, merge_cp_length_p, THREAD);
582 // The above call to append_entry() can only append one entry
583 // so the post call query of *merge_cp_length_p is only for
584 // the sake of consistency.
585 new_ref_i = *merge_cp_length_p - 1;
586 }
587 }
588
589 return new_ref_i;
590 } // end find_or_append_indirect_entry()
591
592
593 // Append a bootstrap specifier into the merge_cp operands that is semantically equal
594 // to the scratch_cp operands bootstrap specifier passed by the old_bs_i index.
595 // Recursively append new merge_cp entries referenced by the new bootstrap specifier.
596 void VM_RedefineClasses::append_operand(const constantPoolHandle& scratch_cp, int old_bs_i,
597 constantPoolHandle *merge_cp_p, int *merge_cp_length_p, TRAPS) {
598
599 int old_ref_i = scratch_cp->operand_bootstrap_method_ref_index_at(old_bs_i);
600 int new_ref_i = find_or_append_indirect_entry(scratch_cp, old_ref_i, merge_cp_p,
601 merge_cp_length_p, THREAD);
602 if (new_ref_i != old_ref_i) {
603 log_trace(redefine, class, constantpool)
604 ("operands entry@%d bootstrap method ref_index change: %d to %d", _operands_cur_length, old_ref_i, new_ref_i);
605 }
606
607 Array<u2>* merge_ops = (*merge_cp_p)->operands();
608 int new_bs_i = _operands_cur_length;
609 // We have _operands_cur_length == 0 when the merge_cp operands is empty yet.
610 // However, the operand_offset_at(0) was set in the extend_operands() call.
611 int new_base = (new_bs_i == 0) ? (*merge_cp_p)->operand_offset_at(0)
612 : (*merge_cp_p)->operand_next_offset_at(new_bs_i - 1);
613 int argc = scratch_cp->operand_argument_count_at(old_bs_i);
614
615 ConstantPool::operand_offset_at_put(merge_ops, _operands_cur_length, new_base);
616 merge_ops->at_put(new_base++, new_ref_i);
617 merge_ops->at_put(new_base++, argc);
618
619 for (int i = 0; i < argc; i++) {
620 int old_arg_ref_i = scratch_cp->operand_argument_index_at(old_bs_i, i);
621 int new_arg_ref_i = find_or_append_indirect_entry(scratch_cp, old_arg_ref_i, merge_cp_p,
622 merge_cp_length_p, THREAD);
623 merge_ops->at_put(new_base++, new_arg_ref_i);
624 if (new_arg_ref_i != old_arg_ref_i) {
625 log_trace(redefine, class, constantpool)
626 ("operands entry@%d bootstrap method argument ref_index change: %d to %d",
627 _operands_cur_length, old_arg_ref_i, new_arg_ref_i);
628 }
629 }
630 if (old_bs_i != _operands_cur_length) {
631 // The bootstrap specifier in *merge_cp_p is at a different index than
632 // that in scratch_cp so we need to map the index values.
633 map_operand_index(old_bs_i, new_bs_i);
634 }
635 _operands_cur_length++;
636 } // end append_operand()
637
638
639 int VM_RedefineClasses::find_or_append_operand(const constantPoolHandle& scratch_cp,
640 int old_bs_i, constantPoolHandle *merge_cp_p, int *merge_cp_length_p, TRAPS) {
641
642 int new_bs_i = old_bs_i; // bootstrap specifier index
643 bool match = (old_bs_i < _operands_cur_length) &&
644 scratch_cp->compare_operand_to(old_bs_i, *merge_cp_p, old_bs_i, THREAD);
645
646 if (!match) {
647 // forward reference in *merge_cp_p or not a direct match
648 int found_i = scratch_cp->find_matching_operand(old_bs_i, *merge_cp_p,
649 _operands_cur_length, THREAD);
650 if (found_i != -1) {
651 guarantee(found_i != old_bs_i, "compare_operand_to() and find_matching_operand() disagree");
652 // found a matching operand somewhere else in *merge_cp_p so just need a mapping
653 new_bs_i = found_i;
654 map_operand_index(old_bs_i, found_i);
655 } else {
656 // no match found so we have to append this bootstrap specifier to *merge_cp_p
657 append_operand(scratch_cp, old_bs_i, merge_cp_p, merge_cp_length_p, THREAD);
658 new_bs_i = _operands_cur_length - 1;
659 }
660 }
661 return new_bs_i;
662 } // end find_or_append_operand()
663
664
665 void VM_RedefineClasses::finalize_operands_merge(const constantPoolHandle& merge_cp, TRAPS) {
666 if (merge_cp->operands() == NULL) {
667 return;
668 }
669 // Shrink the merge_cp operands
670 merge_cp->shrink_operands(_operands_cur_length, CHECK);
671
672 if (log_is_enabled(Trace, redefine, class, constantpool)) {
673 // don't want to loop unless we are tracing
674 int count = 0;
675 for (int i = 1; i < _operands_index_map_p->length(); i++) {
676 int value = _operands_index_map_p->at(i);
677 if (value != -1) {
678 log_trace(redefine, class, constantpool)("operands_index_map[%d]: old=%d new=%d", count, i, value);
679 count++;
680 }
681 }
682 }
683 // Clean-up
684 _operands_index_map_p = NULL;
685 _operands_cur_length = 0;
686 _operands_index_map_count = 0;
687 } // end finalize_operands_merge()
688
689 // Symbol* comparator for qsort
690 // The caller must have an active ResourceMark.
691 static int symcmp(const void* a, const void* b) {
692 char* astr = (*(Symbol**)a)->as_C_string();
693 char* bstr = (*(Symbol**)b)->as_C_string();
694 return strcmp(astr, bstr);
695 }
696
697 static jvmtiError check_nest_attributes(InstanceKlass* the_class,
698 InstanceKlass* scratch_class) {
699 // Check whether the class NestHost attribute has been changed.
700 Thread* thread = Thread::current();
701 ResourceMark rm(thread);
702 u2 the_nest_host_idx = the_class->nest_host_index();
703 u2 scr_nest_host_idx = scratch_class->nest_host_index();
704
705 if (the_nest_host_idx != 0 && scr_nest_host_idx != 0) {
706 Symbol* the_sym = the_class->constants()->klass_name_at(the_nest_host_idx);
707 Symbol* scr_sym = scratch_class->constants()->klass_name_at(scr_nest_host_idx);
708 if (the_sym != scr_sym) {
709 log_trace(redefine, class, nestmates)
710 ("redefined class %s attribute change error: NestHost class: %s replaced with: %s",
711 the_class->external_name(), the_sym->as_C_string(), scr_sym->as_C_string());
712 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_CLASS_ATTRIBUTE_CHANGED;
713 }
714 } else if ((the_nest_host_idx == 0) ^ (scr_nest_host_idx == 0)) {
715 const char* action_str = (the_nest_host_idx != 0) ? "removed" : "added";
716 log_trace(redefine, class, nestmates)
717 ("redefined class %s attribute change error: NestHost attribute %s",
718 the_class->external_name(), action_str);
719 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_CLASS_ATTRIBUTE_CHANGED;
720 }
721
722 // Check whether the class NestMembers attribute has been changed.
723 Array<u2>* the_nest_members = the_class->nest_members();
724 Array<u2>* scr_nest_members = scratch_class->nest_members();
725 bool the_members_exists = the_nest_members != Universe::the_empty_short_array();
726 bool scr_members_exists = scr_nest_members != Universe::the_empty_short_array();
727
728 int members_len = the_nest_members->length();
729 if (the_members_exists && scr_members_exists) {
730 if (members_len != scr_nest_members->length()) {
731 log_trace(redefine, class, nestmates)
732 ("redefined class %s attribute change error: NestMember len=%d changed to len=%d",
733 the_class->external_name(), members_len, scr_nest_members->length());
734 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_CLASS_ATTRIBUTE_CHANGED;
735 }
736
737 // The order of entries in the NestMembers array is not specified so we
738 // have to explicitly check for the same contents. We do this by copying
739 // the referenced symbols into their own arrays, sorting them and then
740 // comparing each element pair.
741
742 Symbol** the_syms = NEW_RESOURCE_ARRAY_RETURN_NULL(Symbol*, members_len);
743 Symbol** scr_syms = NEW_RESOURCE_ARRAY_RETURN_NULL(Symbol*, members_len);
744
745 if (the_syms == NULL || scr_syms == NULL) {
746 return JVMTI_ERROR_OUT_OF_MEMORY;
747 }
748
749 for (int i = 0; i < members_len; i++) {
750 int the_cp_index = the_nest_members->at(i);
751 int scr_cp_index = scr_nest_members->at(i);
752 the_syms[i] = the_class->constants()->klass_name_at(the_cp_index);
753 scr_syms[i] = scratch_class->constants()->klass_name_at(scr_cp_index);
754 }
755
756 qsort(the_syms, members_len, sizeof(Symbol*), symcmp);
757 qsort(scr_syms, members_len, sizeof(Symbol*), symcmp);
758
759 for (int i = 0; i < members_len; i++) {
760 if (the_syms[i] != scr_syms[i]) {
761 log_trace(redefine, class, nestmates)
762 ("redefined class %s attribute change error: NestMembers[%d]: %s changed to %s",
763 the_class->external_name(), i, the_syms[i]->as_C_string(), scr_syms[i]->as_C_string());
764 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_CLASS_ATTRIBUTE_CHANGED;
765 }
766 }
767 } else if (the_members_exists ^ scr_members_exists) {
768 const char* action_str = (the_members_exists) ? "removed" : "added";
769 log_trace(redefine, class, nestmates)
770 ("redefined class %s attribute change error: NestMembers attribute %s",
771 the_class->external_name(), action_str);
772 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_CLASS_ATTRIBUTE_CHANGED;
773 }
774
775 return JVMTI_ERROR_NONE;
776 }
777
778 jvmtiError VM_RedefineClasses::compare_and_normalize_class_versions(
779 InstanceKlass* the_class,
780 InstanceKlass* scratch_class) {
781 int i;
782
783 // Check superclasses, or rather their names, since superclasses themselves can be
784 // requested to replace.
785 // Check for NULL superclass first since this might be java.lang.Object
786 if (the_class->super() != scratch_class->super() &&
787 (the_class->super() == NULL || scratch_class->super() == NULL ||
788 the_class->super()->name() !=
789 scratch_class->super()->name())) {
790 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_HIERARCHY_CHANGED;
791 }
792
793 // Check if the number, names and order of directly implemented interfaces are the same.
794 // I think in principle we should just check if the sets of names of directly implemented
795 // interfaces are the same, i.e. the order of declaration (which, however, if changed in the
796 // .java file, also changes in .class file) should not matter. However, comparing sets is
797 // technically a bit more difficult, and, more importantly, I am not sure at present that the
798 // order of interfaces does not matter on the implementation level, i.e. that the VM does not
799 // rely on it somewhere.
800 Array<InstanceKlass*>* k_interfaces = the_class->local_interfaces();
801 Array<InstanceKlass*>* k_new_interfaces = scratch_class->local_interfaces();
802 int n_intfs = k_interfaces->length();
803 if (n_intfs != k_new_interfaces->length()) {
804 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_HIERARCHY_CHANGED;
805 }
806 for (i = 0; i < n_intfs; i++) {
807 if (k_interfaces->at(i)->name() !=
808 k_new_interfaces->at(i)->name()) {
809 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_HIERARCHY_CHANGED;
810 }
811 }
812
813 // Check whether class is in the error init state.
814 if (the_class->is_in_error_state()) {
815 // TBD #5057930: special error code is needed in 1.6
816 return JVMTI_ERROR_INVALID_CLASS;
817 }
818
819 // Check whether the nest-related attributes have been changed.
820 jvmtiError err = check_nest_attributes(the_class, scratch_class);
821 if (err != JVMTI_ERROR_NONE) {
822 return err;
823 }
824
825 // Check whether class modifiers are the same.
826 jushort old_flags = (jushort) the_class->access_flags().get_flags();
827 jushort new_flags = (jushort) scratch_class->access_flags().get_flags();
828 if (old_flags != new_flags) {
829 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_CLASS_MODIFIERS_CHANGED;
830 }
831
832 // Check if the number, names, types and order of fields declared in these classes
833 // are the same.
834 JavaFieldStream old_fs(the_class);
835 JavaFieldStream new_fs(scratch_class);
836 for (; !old_fs.done() && !new_fs.done(); old_fs.next(), new_fs.next()) {
837 // access
838 old_flags = old_fs.access_flags().as_short();
839 new_flags = new_fs.access_flags().as_short();
840 if ((old_flags ^ new_flags) & JVM_RECOGNIZED_FIELD_MODIFIERS) {
841 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_SCHEMA_CHANGED;
842 }
843 // offset
844 if (old_fs.offset() != new_fs.offset()) {
845 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_SCHEMA_CHANGED;
846 }
847 // name and signature
848 Symbol* name_sym1 = the_class->constants()->symbol_at(old_fs.name_index());
849 Symbol* sig_sym1 = the_class->constants()->symbol_at(old_fs.signature_index());
850 Symbol* name_sym2 = scratch_class->constants()->symbol_at(new_fs.name_index());
851 Symbol* sig_sym2 = scratch_class->constants()->symbol_at(new_fs.signature_index());
852 if (name_sym1 != name_sym2 || sig_sym1 != sig_sym2) {
853 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_SCHEMA_CHANGED;
854 }
855 }
856
857 // If both streams aren't done then we have a differing number of
858 // fields.
859 if (!old_fs.done() || !new_fs.done()) {
860 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_SCHEMA_CHANGED;
861 }
862
863 // Do a parallel walk through the old and new methods. Detect
864 // cases where they match (exist in both), have been added in
865 // the new methods, or have been deleted (exist only in the
866 // old methods). The class file parser places methods in order
867 // by method name, but does not order overloaded methods by
868 // signature. In order to determine what fate befell the methods,
869 // this code places the overloaded new methods that have matching
870 // old methods in the same order as the old methods and places
871 // new overloaded methods at the end of overloaded methods of
872 // that name. The code for this order normalization is adapted
873 // from the algorithm used in InstanceKlass::find_method().
874 // Since we are swapping out of order entries as we find them,
875 // we only have to search forward through the overloaded methods.
876 // Methods which are added and have the same name as an existing
877 // method (but different signature) will be put at the end of
878 // the methods with that name, and the name mismatch code will
879 // handle them.
880 Array<Method*>* k_old_methods(the_class->methods());
881 Array<Method*>* k_new_methods(scratch_class->methods());
882 int n_old_methods = k_old_methods->length();
883 int n_new_methods = k_new_methods->length();
884 Thread* thread = Thread::current();
885
886 int ni = 0;
887 int oi = 0;
888 while (true) {
889 Method* k_old_method;
890 Method* k_new_method;
891 enum { matched, added, deleted, undetermined } method_was = undetermined;
892
893 if (oi >= n_old_methods) {
894 if (ni >= n_new_methods) {
895 break; // we've looked at everything, done
896 }
897 // New method at the end
898 k_new_method = k_new_methods->at(ni);
899 method_was = added;
900 } else if (ni >= n_new_methods) {
901 // Old method, at the end, is deleted
902 k_old_method = k_old_methods->at(oi);
903 method_was = deleted;
904 } else {
905 // There are more methods in both the old and new lists
906 k_old_method = k_old_methods->at(oi);
907 k_new_method = k_new_methods->at(ni);
908 if (k_old_method->name() != k_new_method->name()) {
909 // Methods are sorted by method name, so a mismatch means added
910 // or deleted
911 if (k_old_method->name()->fast_compare(k_new_method->name()) > 0) {
912 method_was = added;
913 } else {
914 method_was = deleted;
915 }
916 } else if (k_old_method->signature() == k_new_method->signature()) {
917 // Both the name and signature match
918 method_was = matched;
919 } else {
920 // The name matches, but the signature doesn't, which means we have to
921 // search forward through the new overloaded methods.
922 int nj; // outside the loop for post-loop check
923 for (nj = ni + 1; nj < n_new_methods; nj++) {
924 Method* m = k_new_methods->at(nj);
925 if (k_old_method->name() != m->name()) {
926 // reached another method name so no more overloaded methods
927 method_was = deleted;
928 break;
929 }
930 if (k_old_method->signature() == m->signature()) {
931 // found a match so swap the methods
932 k_new_methods->at_put(ni, m);
933 k_new_methods->at_put(nj, k_new_method);
934 k_new_method = m;
935 method_was = matched;
936 break;
937 }
938 }
939
940 if (nj >= n_new_methods) {
941 // reached the end without a match; so method was deleted
942 method_was = deleted;
943 }
944 }
945 }
946
947 switch (method_was) {
948 case matched:
949 // methods match, be sure modifiers do too
950 old_flags = (jushort) k_old_method->access_flags().get_flags();
951 new_flags = (jushort) k_new_method->access_flags().get_flags();
952 if ((old_flags ^ new_flags) & ~(JVM_ACC_NATIVE)) {
953 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_METHOD_MODIFIERS_CHANGED;
954 }
955 {
956 u2 new_num = k_new_method->method_idnum();
957 u2 old_num = k_old_method->method_idnum();
958 if (new_num != old_num) {
959 Method* idnum_owner = scratch_class->method_with_idnum(old_num);
960 if (idnum_owner != NULL) {
961 // There is already a method assigned this idnum -- switch them
962 // Take current and original idnum from the new_method
963 idnum_owner->set_method_idnum(new_num);
964 idnum_owner->set_orig_method_idnum(k_new_method->orig_method_idnum());
965 }
966 // Take current and original idnum from the old_method
967 k_new_method->set_method_idnum(old_num);
968 k_new_method->set_orig_method_idnum(k_old_method->orig_method_idnum());
969 if (thread->has_pending_exception()) {
970 return JVMTI_ERROR_OUT_OF_MEMORY;
971 }
972 }
973 }
974 log_trace(redefine, class, normalize)
975 ("Method matched: new: %s [%d] == old: %s [%d]",
976 k_new_method->name_and_sig_as_C_string(), ni, k_old_method->name_and_sig_as_C_string(), oi);
977 // advance to next pair of methods
978 ++oi;
979 ++ni;
980 break;
981 case added:
982 // method added, see if it is OK
983 new_flags = (jushort) k_new_method->access_flags().get_flags();
984 if ((new_flags & JVM_ACC_PRIVATE) == 0
985 // hack: private should be treated as final, but alas
986 || (new_flags & (JVM_ACC_FINAL|JVM_ACC_STATIC)) == 0
987 ) {
988 // new methods must be private
989 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_METHOD_ADDED;
990 }
991 {
992 u2 num = the_class->next_method_idnum();
993 if (num == ConstMethod::UNSET_IDNUM) {
994 // cannot add any more methods
995 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_METHOD_ADDED;
996 }
997 u2 new_num = k_new_method->method_idnum();
998 Method* idnum_owner = scratch_class->method_with_idnum(num);
999 if (idnum_owner != NULL) {
1000 // There is already a method assigned this idnum -- switch them
1001 // Take current and original idnum from the new_method
1002 idnum_owner->set_method_idnum(new_num);
1003 idnum_owner->set_orig_method_idnum(k_new_method->orig_method_idnum());
1004 }
1005 k_new_method->set_method_idnum(num);
1006 k_new_method->set_orig_method_idnum(num);
1007 if (thread->has_pending_exception()) {
1008 return JVMTI_ERROR_OUT_OF_MEMORY;
1009 }
1010 }
1011 log_trace(redefine, class, normalize)
1012 ("Method added: new: %s [%d]", k_new_method->name_and_sig_as_C_string(), ni);
1013 ++ni; // advance to next new method
1014 break;
1015 case deleted:
1016 // method deleted, see if it is OK
1017 old_flags = (jushort) k_old_method->access_flags().get_flags();
1018 if ((old_flags & JVM_ACC_PRIVATE) == 0
1019 // hack: private should be treated as final, but alas
1020 || (old_flags & (JVM_ACC_FINAL|JVM_ACC_STATIC)) == 0
1021 ) {
1022 // deleted methods must be private
1023 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_METHOD_DELETED;
1024 }
1025 log_trace(redefine, class, normalize)
1026 ("Method deleted: old: %s [%d]", k_old_method->name_and_sig_as_C_string(), oi);
1027 ++oi; // advance to next old method
1028 break;
1029 default:
1030 ShouldNotReachHere();
1031 }
1032 }
1033
1034 return JVMTI_ERROR_NONE;
1035 }
1036
1037
1038 // Find new constant pool index value for old constant pool index value
1039 // by seaching the index map. Returns zero (0) if there is no mapped
1040 // value for the old constant pool index.
1041 int VM_RedefineClasses::find_new_index(int old_index) {
1042 if (_index_map_count == 0) {
1043 // map is empty so nothing can be found
1044 return 0;
1045 }
1046
1047 if (old_index < 1 || old_index >= _index_map_p->length()) {
1048 // The old_index is out of range so it is not mapped. This should
1049 // not happen in regular constant pool merging use, but it can
1050 // happen if a corrupt annotation is processed.
1051 return 0;
1052 }
1053
1054 int value = _index_map_p->at(old_index);
1055 if (value == -1) {
1056 // the old_index is not mapped
1057 return 0;
1058 }
1059
1060 return value;
1061 } // end find_new_index()
1062
1063
1064 // Find new bootstrap specifier index value for old bootstrap specifier index
1065 // value by seaching the index map. Returns unused index (-1) if there is
1066 // no mapped value for the old bootstrap specifier index.
1067 int VM_RedefineClasses::find_new_operand_index(int old_index) {
1068 if (_operands_index_map_count == 0) {
1069 // map is empty so nothing can be found
1070 return -1;
1071 }
1072
1073 if (old_index == -1 || old_index >= _operands_index_map_p->length()) {
1074 // The old_index is out of range so it is not mapped.
1075 // This should not happen in regular constant pool merging use.
1076 return -1;
1077 }
1078
1079 int value = _operands_index_map_p->at(old_index);
1080 if (value == -1) {
1081 // the old_index is not mapped
1082 return -1;
1083 }
1084
1085 return value;
1086 } // end find_new_operand_index()
1087
1088
1089 // Returns true if the current mismatch is due to a resolved/unresolved
1090 // class pair. Otherwise, returns false.
1091 bool VM_RedefineClasses::is_unresolved_class_mismatch(const constantPoolHandle& cp1,
1092 int index1, const constantPoolHandle& cp2, int index2) {
1093
1094 jbyte t1 = cp1->tag_at(index1).value();
1095 if (t1 != JVM_CONSTANT_Class && t1 != JVM_CONSTANT_UnresolvedClass) {
1096 return false; // wrong entry type; not our special case
1097 }
1098
1099 jbyte t2 = cp2->tag_at(index2).value();
1100 if (t2 != JVM_CONSTANT_Class && t2 != JVM_CONSTANT_UnresolvedClass) {
1101 return false; // wrong entry type; not our special case
1102 }
1103
1104 if (t1 == t2) {
1105 return false; // not a mismatch; not our special case
1106 }
1107
1108 char *s1 = cp1->klass_name_at(index1)->as_C_string();
1109 char *s2 = cp2->klass_name_at(index2)->as_C_string();
1110 if (strcmp(s1, s2) != 0) {
1111 return false; // strings don't match; not our special case
1112 }
1113
1114 return true; // made it through the gauntlet; this is our special case
1115 } // end is_unresolved_class_mismatch()
1116
1117
1118 jvmtiError VM_RedefineClasses::load_new_class_versions(TRAPS) {
1119
1120 // For consistency allocate memory using os::malloc wrapper.
1121 _scratch_classes = (InstanceKlass**)
1122 os::malloc(sizeof(InstanceKlass*) * _class_count, mtClass);
1123 if (_scratch_classes == NULL) {
1124 return JVMTI_ERROR_OUT_OF_MEMORY;
1125 }
1126 // Zero initialize the _scratch_classes array.
1127 for (int i = 0; i < _class_count; i++) {
1128 _scratch_classes[i] = NULL;
1129 }
1130
1131 ResourceMark rm(THREAD);
1132
1133 JvmtiThreadState *state = JvmtiThreadState::state_for(JavaThread::current());
1134 // state can only be NULL if the current thread is exiting which
1135 // should not happen since we're trying to do a RedefineClasses
1136 guarantee(state != NULL, "exiting thread calling load_new_class_versions");
1137 for (int i = 0; i < _class_count; i++) {
1138 // Create HandleMark so that any handles created while loading new class
1139 // versions are deleted. Constant pools are deallocated while merging
1140 // constant pools
1141 HandleMark hm(THREAD);
1142 InstanceKlass* the_class = get_ik(_class_defs[i].klass);
1143 Symbol* the_class_sym = the_class->name();
1144
1145 log_debug(redefine, class, load)
1146 ("loading name=%s kind=%d (avail_mem=" UINT64_FORMAT "K)",
1147 the_class->external_name(), _class_load_kind, os::available_memory() >> 10);
1148
1149 ClassFileStream st((u1*)_class_defs[i].class_bytes,
1150 _class_defs[i].class_byte_count,
1151 "__VM_RedefineClasses__",
1152 ClassFileStream::verify);
1153
1154 // Parse the stream.
1155 Handle the_class_loader(THREAD, the_class->class_loader());
1156 Handle protection_domain(THREAD, the_class->protection_domain());
1157 // Set redefined class handle in JvmtiThreadState class.
1158 // This redefined class is sent to agent event handler for class file
1159 // load hook event.
1160 state->set_class_being_redefined(the_class, _class_load_kind);
1161
1162 InstanceKlass* scratch_class = SystemDictionary::parse_stream(
1163 the_class_sym,
1164 the_class_loader,
1165 protection_domain,
1166 &st,
1167 THREAD);
1168 // Clear class_being_redefined just to be sure.
1169 state->clear_class_being_redefined();
1170
1171 // TODO: if this is retransform, and nothing changed we can skip it
1172
1173 // Need to clean up allocated InstanceKlass if there's an error so assign
1174 // the result here. Caller deallocates all the scratch classes in case of
1175 // an error.
1176 _scratch_classes[i] = scratch_class;
1177
1178 if (HAS_PENDING_EXCEPTION) {
1179 Symbol* ex_name = PENDING_EXCEPTION->klass()->name();
1180 log_info(redefine, class, load, exceptions)("parse_stream exception: '%s'", ex_name->as_C_string());
1181 CLEAR_PENDING_EXCEPTION;
1182
1183 if (ex_name == vmSymbols::java_lang_UnsupportedClassVersionError()) {
1184 return JVMTI_ERROR_UNSUPPORTED_VERSION;
1185 } else if (ex_name == vmSymbols::java_lang_ClassFormatError()) {
1186 return JVMTI_ERROR_INVALID_CLASS_FORMAT;
1187 } else if (ex_name == vmSymbols::java_lang_ClassCircularityError()) {
1188 return JVMTI_ERROR_CIRCULAR_CLASS_DEFINITION;
1189 } else if (ex_name == vmSymbols::java_lang_NoClassDefFoundError()) {
1190 // The message will be "XXX (wrong name: YYY)"
1191 return JVMTI_ERROR_NAMES_DONT_MATCH;
1192 } else if (ex_name == vmSymbols::java_lang_OutOfMemoryError()) {
1193 return JVMTI_ERROR_OUT_OF_MEMORY;
1194 } else { // Just in case more exceptions can be thrown..
1195 return JVMTI_ERROR_FAILS_VERIFICATION;
1196 }
1197 }
1198
1199 // Ensure class is linked before redefine
1200 if (!the_class->is_linked()) {
1201 the_class->link_class(THREAD);
1202 if (HAS_PENDING_EXCEPTION) {
1203 Symbol* ex_name = PENDING_EXCEPTION->klass()->name();
1204 log_info(redefine, class, load, exceptions)("link_class exception: '%s'", ex_name->as_C_string());
1205 CLEAR_PENDING_EXCEPTION;
1206 if (ex_name == vmSymbols::java_lang_OutOfMemoryError()) {
1207 return JVMTI_ERROR_OUT_OF_MEMORY;
1208 } else {
1209 return JVMTI_ERROR_INTERNAL;
1210 }
1211 }
1212 }
1213
1214 // Do the validity checks in compare_and_normalize_class_versions()
1215 // before verifying the byte codes. By doing these checks first, we
1216 // limit the number of functions that require redirection from
1217 // the_class to scratch_class. In particular, we don't have to
1218 // modify JNI GetSuperclass() and thus won't change its performance.
1219 jvmtiError res = compare_and_normalize_class_versions(the_class,
1220 scratch_class);
1221 if (res != JVMTI_ERROR_NONE) {
1222 return res;
1223 }
1224
1225 // verify what the caller passed us
1226 {
1227 // The bug 6214132 caused the verification to fail.
1228 // Information about the_class and scratch_class is temporarily
1229 // recorded into jvmtiThreadState. This data is used to redirect
1230 // the_class to scratch_class in the JVM_* functions called by the
1231 // verifier. Please, refer to jvmtiThreadState.hpp for the detailed
1232 // description.
1233 RedefineVerifyMark rvm(the_class, scratch_class, state);
1234 Verifier::verify(scratch_class, true, THREAD);
1235 }
1236
1237 if (HAS_PENDING_EXCEPTION) {
1238 Symbol* ex_name = PENDING_EXCEPTION->klass()->name();
1239 log_info(redefine, class, load, exceptions)("verify_byte_codes exception: '%s'", ex_name->as_C_string());
1240 CLEAR_PENDING_EXCEPTION;
1241 if (ex_name == vmSymbols::java_lang_OutOfMemoryError()) {
1242 return JVMTI_ERROR_OUT_OF_MEMORY;
1243 } else {
1244 // tell the caller the bytecodes are bad
1245 return JVMTI_ERROR_FAILS_VERIFICATION;
1246 }
1247 }
1248
1249 res = merge_cp_and_rewrite(the_class, scratch_class, THREAD);
1250 if (HAS_PENDING_EXCEPTION) {
1251 Symbol* ex_name = PENDING_EXCEPTION->klass()->name();
1252 log_info(redefine, class, load, exceptions)("merge_cp_and_rewrite exception: '%s'", ex_name->as_C_string());
1253 CLEAR_PENDING_EXCEPTION;
1254 if (ex_name == vmSymbols::java_lang_OutOfMemoryError()) {
1255 return JVMTI_ERROR_OUT_OF_MEMORY;
1256 } else {
1257 return JVMTI_ERROR_INTERNAL;
1258 }
1259 }
1260
1261 if (VerifyMergedCPBytecodes) {
1262 // verify what we have done during constant pool merging
1263 {
1264 RedefineVerifyMark rvm(the_class, scratch_class, state);
1265 Verifier::verify(scratch_class, true, THREAD);
1266 }
1267
1268 if (HAS_PENDING_EXCEPTION) {
1269 Symbol* ex_name = PENDING_EXCEPTION->klass()->name();
1270 log_info(redefine, class, load, exceptions)
1271 ("verify_byte_codes post merge-CP exception: '%s'", ex_name->as_C_string());
1272 CLEAR_PENDING_EXCEPTION;
1273 if (ex_name == vmSymbols::java_lang_OutOfMemoryError()) {
1274 return JVMTI_ERROR_OUT_OF_MEMORY;
1275 } else {
1276 // tell the caller that constant pool merging screwed up
1277 return JVMTI_ERROR_INTERNAL;
1278 }
1279 }
1280 }
1281
1282 Rewriter::rewrite(scratch_class, THREAD);
1283 if (!HAS_PENDING_EXCEPTION) {
1284 scratch_class->link_methods(THREAD);
1285 }
1286 if (HAS_PENDING_EXCEPTION) {
1287 Symbol* ex_name = PENDING_EXCEPTION->klass()->name();
1288 log_info(redefine, class, load, exceptions)
1289 ("Rewriter::rewrite or link_methods exception: '%s'", ex_name->as_C_string());
1290 CLEAR_PENDING_EXCEPTION;
1291 if (ex_name == vmSymbols::java_lang_OutOfMemoryError()) {
1292 return JVMTI_ERROR_OUT_OF_MEMORY;
1293 } else {
1294 return JVMTI_ERROR_INTERNAL;
1295 }
1296 }
1297
1298 log_debug(redefine, class, load)
1299 ("loaded name=%s (avail_mem=" UINT64_FORMAT "K)", the_class->external_name(), os::available_memory() >> 10);
1300 }
1301
1302 return JVMTI_ERROR_NONE;
1303 }
1304
1305
1306 // Map old_index to new_index as needed. scratch_cp is only needed
1307 // for log calls.
1308 void VM_RedefineClasses::map_index(const constantPoolHandle& scratch_cp,
1309 int old_index, int new_index) {
1310 if (find_new_index(old_index) != 0) {
1311 // old_index is already mapped
1312 return;
1313 }
1314
1315 if (old_index == new_index) {
1316 // no mapping is needed
1317 return;
1318 }
1319
1320 _index_map_p->at_put(old_index, new_index);
1321 _index_map_count++;
1322
1323 log_trace(redefine, class, constantpool)
1324 ("mapped tag %d at index %d to %d", scratch_cp->tag_at(old_index).value(), old_index, new_index);
1325 } // end map_index()
1326
1327
1328 // Map old_index to new_index as needed.
1329 void VM_RedefineClasses::map_operand_index(int old_index, int new_index) {
1330 if (find_new_operand_index(old_index) != -1) {
1331 // old_index is already mapped
1332 return;
1333 }
1334
1335 if (old_index == new_index) {
1336 // no mapping is needed
1337 return;
1338 }
1339
1340 _operands_index_map_p->at_put(old_index, new_index);
1341 _operands_index_map_count++;
1342
1343 log_trace(redefine, class, constantpool)("mapped bootstrap specifier at index %d to %d", old_index, new_index);
1344 } // end map_index()
1345
1346
1347 // Merge old_cp and scratch_cp and return the results of the merge via
1348 // merge_cp_p. The number of entries in *merge_cp_p is returned via
1349 // merge_cp_length_p. The entries in old_cp occupy the same locations
1350 // in *merge_cp_p. Also creates a map of indices from entries in
1351 // scratch_cp to the corresponding entry in *merge_cp_p. Index map
1352 // entries are only created for entries in scratch_cp that occupy a
1353 // different location in *merged_cp_p.
1354 bool VM_RedefineClasses::merge_constant_pools(const constantPoolHandle& old_cp,
1355 const constantPoolHandle& scratch_cp, constantPoolHandle *merge_cp_p,
1356 int *merge_cp_length_p, TRAPS) {
1357
1358 if (merge_cp_p == NULL) {
1359 assert(false, "caller must provide scratch constantPool");
1360 return false; // robustness
1361 }
1362 if (merge_cp_length_p == NULL) {
1363 assert(false, "caller must provide scratch CP length");
1364 return false; // robustness
1365 }
1366 // Worst case we need old_cp->length() + scratch_cp()->length(),
1367 // but the caller might be smart so make sure we have at least
1368 // the minimum.
1369 if ((*merge_cp_p)->length() < old_cp->length()) {
1370 assert(false, "merge area too small");
1371 return false; // robustness
1372 }
1373
1374 log_info(redefine, class, constantpool)("old_cp_len=%d, scratch_cp_len=%d", old_cp->length(), scratch_cp->length());
1375
1376 {
1377 // Pass 0:
1378 // The old_cp is copied to *merge_cp_p; this means that any code
1379 // using old_cp does not have to change. This work looks like a
1380 // perfect fit for ConstantPool*::copy_cp_to(), but we need to
1381 // handle one special case:
1382 // - revert JVM_CONSTANT_Class to JVM_CONSTANT_UnresolvedClass
1383 // This will make verification happy.
1384
1385 int old_i; // index into old_cp
1386
1387 // index zero (0) is not used in constantPools
1388 for (old_i = 1; old_i < old_cp->length(); old_i++) {
1389 // leave debugging crumb
1390 jbyte old_tag = old_cp->tag_at(old_i).value();
1391 switch (old_tag) {
1392 case JVM_CONSTANT_Class:
1393 case JVM_CONSTANT_UnresolvedClass:
1394 // revert the copy to JVM_CONSTANT_UnresolvedClass
1395 // May be resolving while calling this so do the same for
1396 // JVM_CONSTANT_UnresolvedClass (klass_name_at() deals with transition)
1397 (*merge_cp_p)->temp_unresolved_klass_at_put(old_i,
1398 old_cp->klass_name_index_at(old_i));
1399 break;
1400
1401 case JVM_CONSTANT_Double:
1402 case JVM_CONSTANT_Long:
1403 // just copy the entry to *merge_cp_p, but double and long take
1404 // two constant pool entries
1405 ConstantPool::copy_entry_to(old_cp, old_i, *merge_cp_p, old_i, CHECK_0);
1406 old_i++;
1407 break;
1408
1409 default:
1410 // just copy the entry to *merge_cp_p
1411 ConstantPool::copy_entry_to(old_cp, old_i, *merge_cp_p, old_i, CHECK_0);
1412 break;
1413 }
1414 } // end for each old_cp entry
1415
1416 ConstantPool::copy_operands(old_cp, *merge_cp_p, CHECK_0);
1417 (*merge_cp_p)->extend_operands(scratch_cp, CHECK_0);
1418
1419 // We don't need to sanity check that *merge_cp_length_p is within
1420 // *merge_cp_p bounds since we have the minimum on-entry check above.
1421 (*merge_cp_length_p) = old_i;
1422 }
1423
1424 // merge_cp_len should be the same as old_cp->length() at this point
1425 // so this trace message is really a "warm-and-breathing" message.
1426 log_debug(redefine, class, constantpool)("after pass 0: merge_cp_len=%d", *merge_cp_length_p);
1427
1428 int scratch_i; // index into scratch_cp
1429 {
1430 // Pass 1a:
1431 // Compare scratch_cp entries to the old_cp entries that we have
1432 // already copied to *merge_cp_p. In this pass, we are eliminating
1433 // exact duplicates (matching entry at same index) so we only
1434 // compare entries in the common indice range.
1435 int increment = 1;
1436 int pass1a_length = MIN2(old_cp->length(), scratch_cp->length());
1437 for (scratch_i = 1; scratch_i < pass1a_length; scratch_i += increment) {
1438 switch (scratch_cp->tag_at(scratch_i).value()) {
1439 case JVM_CONSTANT_Double:
1440 case JVM_CONSTANT_Long:
1441 // double and long take two constant pool entries
1442 increment = 2;
1443 break;
1444
1445 default:
1446 increment = 1;
1447 break;
1448 }
1449
1450 bool match = scratch_cp->compare_entry_to(scratch_i, *merge_cp_p,
1451 scratch_i, CHECK_0);
1452 if (match) {
1453 // found a match at the same index so nothing more to do
1454 continue;
1455 } else if (is_unresolved_class_mismatch(scratch_cp, scratch_i,
1456 *merge_cp_p, scratch_i)) {
1457 // The mismatch in compare_entry_to() above is because of a
1458 // resolved versus unresolved class entry at the same index
1459 // with the same string value. Since Pass 0 reverted any
1460 // class entries to unresolved class entries in *merge_cp_p,
1461 // we go with the unresolved class entry.
1462 continue;
1463 }
1464
1465 int found_i = scratch_cp->find_matching_entry(scratch_i, *merge_cp_p,
1466 CHECK_0);
1467 if (found_i != 0) {
1468 guarantee(found_i != scratch_i,
1469 "compare_entry_to() and find_matching_entry() do not agree");
1470
1471 // Found a matching entry somewhere else in *merge_cp_p so
1472 // just need a mapping entry.
1473 map_index(scratch_cp, scratch_i, found_i);
1474 continue;
1475 }
1476
1477 // The find_matching_entry() call above could fail to find a match
1478 // due to a resolved versus unresolved class or string entry situation
1479 // like we solved above with the is_unresolved_*_mismatch() calls.
1480 // However, we would have to call is_unresolved_*_mismatch() over
1481 // all of *merge_cp_p (potentially) and that doesn't seem to be
1482 // worth the time.
1483
1484 // No match found so we have to append this entry and any unique
1485 // referenced entries to *merge_cp_p.
1486 append_entry(scratch_cp, scratch_i, merge_cp_p, merge_cp_length_p,
1487 CHECK_0);
1488 }
1489 }
1490
1491 log_debug(redefine, class, constantpool)
1492 ("after pass 1a: merge_cp_len=%d, scratch_i=%d, index_map_len=%d",
1493 *merge_cp_length_p, scratch_i, _index_map_count);
1494
1495 if (scratch_i < scratch_cp->length()) {
1496 // Pass 1b:
1497 // old_cp is smaller than scratch_cp so there are entries in
1498 // scratch_cp that we have not yet processed. We take care of
1499 // those now.
1500 int increment = 1;
1501 for (; scratch_i < scratch_cp->length(); scratch_i += increment) {
1502 switch (scratch_cp->tag_at(scratch_i).value()) {
1503 case JVM_CONSTANT_Double:
1504 case JVM_CONSTANT_Long:
1505 // double and long take two constant pool entries
1506 increment = 2;
1507 break;
1508
1509 default:
1510 increment = 1;
1511 break;
1512 }
1513
1514 int found_i =
1515 scratch_cp->find_matching_entry(scratch_i, *merge_cp_p, CHECK_0);
1516 if (found_i != 0) {
1517 // Found a matching entry somewhere else in *merge_cp_p so
1518 // just need a mapping entry.
1519 map_index(scratch_cp, scratch_i, found_i);
1520 continue;
1521 }
1522
1523 // No match found so we have to append this entry and any unique
1524 // referenced entries to *merge_cp_p.
1525 append_entry(scratch_cp, scratch_i, merge_cp_p, merge_cp_length_p,
1526 CHECK_0);
1527 }
1528
1529 log_debug(redefine, class, constantpool)
1530 ("after pass 1b: merge_cp_len=%d, scratch_i=%d, index_map_len=%d",
1531 *merge_cp_length_p, scratch_i, _index_map_count);
1532 }
1533 finalize_operands_merge(*merge_cp_p, THREAD);
1534
1535 return true;
1536 } // end merge_constant_pools()
1537
1538
1539 // Scoped object to clean up the constant pool(s) created for merging
1540 class MergeCPCleaner {
1541 ClassLoaderData* _loader_data;
1542 ConstantPool* _cp;
1543 ConstantPool* _scratch_cp;
1544 public:
1545 MergeCPCleaner(ClassLoaderData* loader_data, ConstantPool* merge_cp) :
1546 _loader_data(loader_data), _cp(merge_cp), _scratch_cp(NULL) {}
1547 ~MergeCPCleaner() {
1548 _loader_data->add_to_deallocate_list(_cp);
1549 if (_scratch_cp != NULL) {
1550 _loader_data->add_to_deallocate_list(_scratch_cp);
1551 }
1552 }
1553 void add_scratch_cp(ConstantPool* scratch_cp) { _scratch_cp = scratch_cp; }
1554 };
1555
1556 // Merge constant pools between the_class and scratch_class and
1557 // potentially rewrite bytecodes in scratch_class to use the merged
1558 // constant pool.
1559 jvmtiError VM_RedefineClasses::merge_cp_and_rewrite(
1560 InstanceKlass* the_class, InstanceKlass* scratch_class,
1561 TRAPS) {
1562 // worst case merged constant pool length is old and new combined
1563 int merge_cp_length = the_class->constants()->length()
1564 + scratch_class->constants()->length();
1565
1566 // Constant pools are not easily reused so we allocate a new one
1567 // each time.
1568 // merge_cp is created unsafe for concurrent GC processing. It
1569 // should be marked safe before discarding it. Even though
1570 // garbage, if it crosses a card boundary, it may be scanned
1571 // in order to find the start of the first complete object on the card.
1572 ClassLoaderData* loader_data = the_class->class_loader_data();
1573 ConstantPool* merge_cp_oop =
1574 ConstantPool::allocate(loader_data,
1575 merge_cp_length,
1576 CHECK_(JVMTI_ERROR_OUT_OF_MEMORY));
1577 MergeCPCleaner cp_cleaner(loader_data, merge_cp_oop);
1578
1579 HandleMark hm(THREAD); // make sure handles are cleared before
1580 // MergeCPCleaner clears out merge_cp_oop
1581 constantPoolHandle merge_cp(THREAD, merge_cp_oop);
1582
1583 // Get constants() from the old class because it could have been rewritten
1584 // while we were at a safepoint allocating a new constant pool.
1585 constantPoolHandle old_cp(THREAD, the_class->constants());
1586 constantPoolHandle scratch_cp(THREAD, scratch_class->constants());
1587
1588 // If the length changed, the class was redefined out from under us. Return
1589 // an error.
1590 if (merge_cp_length != the_class->constants()->length()
1591 + scratch_class->constants()->length()) {
1592 return JVMTI_ERROR_INTERNAL;
1593 }
1594
1595 // Update the version number of the constant pools (may keep scratch_cp)
1596 merge_cp->increment_and_save_version(old_cp->version());
1597 scratch_cp->increment_and_save_version(old_cp->version());
1598
1599 ResourceMark rm(THREAD);
1600 _index_map_count = 0;
1601 _index_map_p = new intArray(scratch_cp->length(), scratch_cp->length(), -1);
1602
1603 _operands_cur_length = ConstantPool::operand_array_length(old_cp->operands());
1604 _operands_index_map_count = 0;
1605 int operands_index_map_len = ConstantPool::operand_array_length(scratch_cp->operands());
1606 _operands_index_map_p = new intArray(operands_index_map_len, operands_index_map_len, -1);
1607
1608 // reference to the cp holder is needed for copy_operands()
1609 merge_cp->set_pool_holder(scratch_class);
1610 bool result = merge_constant_pools(old_cp, scratch_cp, &merge_cp,
1611 &merge_cp_length, THREAD);
1612 merge_cp->set_pool_holder(NULL);
1613
1614 if (!result) {
1615 // The merge can fail due to memory allocation failure or due
1616 // to robustness checks.
1617 return JVMTI_ERROR_INTERNAL;
1618 }
1619
1620 log_info(redefine, class, constantpool)("merge_cp_len=%d, index_map_len=%d", merge_cp_length, _index_map_count);
1621
1622 if (_index_map_count == 0) {
1623 // there is nothing to map between the new and merged constant pools
1624
1625 if (old_cp->length() == scratch_cp->length()) {
1626 // The old and new constant pools are the same length and the
1627 // index map is empty. This means that the three constant pools
1628 // are equivalent (but not the same). Unfortunately, the new
1629 // constant pool has not gone through link resolution nor have
1630 // the new class bytecodes gone through constant pool cache
1631 // rewriting so we can't use the old constant pool with the new
1632 // class.
1633
1634 // toss the merged constant pool at return
1635 } else if (old_cp->length() < scratch_cp->length()) {
1636 // The old constant pool has fewer entries than the new constant
1637 // pool and the index map is empty. This means the new constant
1638 // pool is a superset of the old constant pool. However, the old
1639 // class bytecodes have already gone through constant pool cache
1640 // rewriting so we can't use the new constant pool with the old
1641 // class.
1642
1643 // toss the merged constant pool at return
1644 } else {
1645 // The old constant pool has more entries than the new constant
1646 // pool and the index map is empty. This means that both the old
1647 // and merged constant pools are supersets of the new constant
1648 // pool.
1649
1650 // Replace the new constant pool with a shrunken copy of the
1651 // merged constant pool
1652 set_new_constant_pool(loader_data, scratch_class, merge_cp, merge_cp_length,
1653 CHECK_(JVMTI_ERROR_OUT_OF_MEMORY));
1654 // The new constant pool replaces scratch_cp so have cleaner clean it up.
1655 // It can't be cleaned up while there are handles to it.
1656 cp_cleaner.add_scratch_cp(scratch_cp());
1657 }
1658 } else {
1659 if (log_is_enabled(Trace, redefine, class, constantpool)) {
1660 // don't want to loop unless we are tracing
1661 int count = 0;
1662 for (int i = 1; i < _index_map_p->length(); i++) {
1663 int value = _index_map_p->at(i);
1664
1665 if (value != -1) {
1666 log_trace(redefine, class, constantpool)("index_map[%d]: old=%d new=%d", count, i, value);
1667 count++;
1668 }
1669 }
1670 }
1671
1672 // We have entries mapped between the new and merged constant pools
1673 // so we have to rewrite some constant pool references.
1674 if (!rewrite_cp_refs(scratch_class, THREAD)) {
1675 return JVMTI_ERROR_INTERNAL;
1676 }
1677
1678 // Replace the new constant pool with a shrunken copy of the
1679 // merged constant pool so now the rewritten bytecodes have
1680 // valid references; the previous new constant pool will get
1681 // GCed.
1682 set_new_constant_pool(loader_data, scratch_class, merge_cp, merge_cp_length,
1683 CHECK_(JVMTI_ERROR_OUT_OF_MEMORY));
1684 // The new constant pool replaces scratch_cp so have cleaner clean it up.
1685 // It can't be cleaned up while there are handles to it.
1686 cp_cleaner.add_scratch_cp(scratch_cp());
1687 }
1688
1689 return JVMTI_ERROR_NONE;
1690 } // end merge_cp_and_rewrite()
1691
1692
1693 // Rewrite constant pool references in klass scratch_class.
1694 bool VM_RedefineClasses::rewrite_cp_refs(InstanceKlass* scratch_class,
1695 TRAPS) {
1696
1697 // rewrite constant pool references in the nest attributes:
1698 if (!rewrite_cp_refs_in_nest_attributes(scratch_class)) {
1699 // propagate failure back to caller
1700 return false;
1701 }
1702
1703 // rewrite constant pool references in the methods:
1704 if (!rewrite_cp_refs_in_methods(scratch_class, THREAD)) {
1705 // propagate failure back to caller
1706 return false;
1707 }
1708
1709 // rewrite constant pool references in the class_annotations:
1710 if (!rewrite_cp_refs_in_class_annotations(scratch_class, THREAD)) {
1711 // propagate failure back to caller
1712 return false;
1713 }
1714
1715 // rewrite constant pool references in the fields_annotations:
1716 if (!rewrite_cp_refs_in_fields_annotations(scratch_class, THREAD)) {
1717 // propagate failure back to caller
1718 return false;
1719 }
1720
1721 // rewrite constant pool references in the methods_annotations:
1722 if (!rewrite_cp_refs_in_methods_annotations(scratch_class, THREAD)) {
1723 // propagate failure back to caller
1724 return false;
1725 }
1726
1727 // rewrite constant pool references in the methods_parameter_annotations:
1728 if (!rewrite_cp_refs_in_methods_parameter_annotations(scratch_class,
1729 THREAD)) {
1730 // propagate failure back to caller
1731 return false;
1732 }
1733
1734 // rewrite constant pool references in the methods_default_annotations:
1735 if (!rewrite_cp_refs_in_methods_default_annotations(scratch_class,
1736 THREAD)) {
1737 // propagate failure back to caller
1738 return false;
1739 }
1740
1741 // rewrite constant pool references in the class_type_annotations:
1742 if (!rewrite_cp_refs_in_class_type_annotations(scratch_class, THREAD)) {
1743 // propagate failure back to caller
1744 return false;
1745 }
1746
1747 // rewrite constant pool references in the fields_type_annotations:
1748 if (!rewrite_cp_refs_in_fields_type_annotations(scratch_class, THREAD)) {
1749 // propagate failure back to caller
1750 return false;
1751 }
1752
1753 // rewrite constant pool references in the methods_type_annotations:
1754 if (!rewrite_cp_refs_in_methods_type_annotations(scratch_class, THREAD)) {
1755 // propagate failure back to caller
1756 return false;
1757 }
1758
1759 // There can be type annotations in the Code part of a method_info attribute.
1760 // These annotations are not accessible, even by reflection.
1761 // Currently they are not even parsed by the ClassFileParser.
1762 // If runtime access is added they will also need to be rewritten.
1763
1764 // rewrite source file name index:
1765 u2 source_file_name_idx = scratch_class->source_file_name_index();
1766 if (source_file_name_idx != 0) {
1767 u2 new_source_file_name_idx = find_new_index(source_file_name_idx);
1768 if (new_source_file_name_idx != 0) {
1769 scratch_class->set_source_file_name_index(new_source_file_name_idx);
1770 }
1771 }
1772
1773 // rewrite class generic signature index:
1774 u2 generic_signature_index = scratch_class->generic_signature_index();
1775 if (generic_signature_index != 0) {
1776 u2 new_generic_signature_index = find_new_index(generic_signature_index);
1777 if (new_generic_signature_index != 0) {
1778 scratch_class->set_generic_signature_index(new_generic_signature_index);
1779 }
1780 }
1781
1782 return true;
1783 } // end rewrite_cp_refs()
1784
1785 // Rewrite constant pool references in the NestHost and NestMembers attributes.
1786 bool VM_RedefineClasses::rewrite_cp_refs_in_nest_attributes(
1787 InstanceKlass* scratch_class) {
1788
1789 u2 cp_index = scratch_class->nest_host_index();
1790 if (cp_index != 0) {
1791 scratch_class->set_nest_host_index(find_new_index(cp_index));
1792 }
1793 Array<u2>* nest_members = scratch_class->nest_members();
1794 for (int i = 0; i < nest_members->length(); i++) {
1795 u2 cp_index = nest_members->at(i);
1796 nest_members->at_put(i, find_new_index(cp_index));
1797 }
1798 return true;
1799 }
1800
1801 // Rewrite constant pool references in the methods.
1802 bool VM_RedefineClasses::rewrite_cp_refs_in_methods(
1803 InstanceKlass* scratch_class, TRAPS) {
1804
1805 Array<Method*>* methods = scratch_class->methods();
1806
1807 if (methods == NULL || methods->length() == 0) {
1808 // no methods so nothing to do
1809 return true;
1810 }
1811
1812 // rewrite constant pool references in the methods:
1813 for (int i = methods->length() - 1; i >= 0; i--) {
1814 methodHandle method(THREAD, methods->at(i));
1815 methodHandle new_method;
1816 rewrite_cp_refs_in_method(method, &new_method, THREAD);
1817 if (!new_method.is_null()) {
1818 // the method has been replaced so save the new method version
1819 // even in the case of an exception. original method is on the
1820 // deallocation list.
1821 methods->at_put(i, new_method());
1822 }
1823 if (HAS_PENDING_EXCEPTION) {
1824 Symbol* ex_name = PENDING_EXCEPTION->klass()->name();
1825 log_info(redefine, class, load, exceptions)("rewrite_cp_refs_in_method exception: '%s'", ex_name->as_C_string());
1826 // Need to clear pending exception here as the super caller sets
1827 // the JVMTI_ERROR_INTERNAL if the returned value is false.
1828 CLEAR_PENDING_EXCEPTION;
1829 return false;
1830 }
1831 }
1832
1833 return true;
1834 }
1835
1836
1837 // Rewrite constant pool references in the specific method. This code
1838 // was adapted from Rewriter::rewrite_method().
1839 void VM_RedefineClasses::rewrite_cp_refs_in_method(methodHandle method,
1840 methodHandle *new_method_p, TRAPS) {
1841
1842 *new_method_p = methodHandle(); // default is no new method
1843
1844 // We cache a pointer to the bytecodes here in code_base. If GC
1845 // moves the Method*, then the bytecodes will also move which
1846 // will likely cause a crash. We create a NoSafepointVerifier
1847 // object to detect whether we pass a possible safepoint in this
1848 // code block.
1849 NoSafepointVerifier nsv;
1850
1851 // Bytecodes and their length
1852 address code_base = method->code_base();
1853 int code_length = method->code_size();
1854
1855 int bc_length;
1856 for (int bci = 0; bci < code_length; bci += bc_length) {
1857 address bcp = code_base + bci;
1858 Bytecodes::Code c = (Bytecodes::Code)(*bcp);
1859
1860 bc_length = Bytecodes::length_for(c);
1861 if (bc_length == 0) {
1862 // More complicated bytecodes report a length of zero so
1863 // we have to try again a slightly different way.
1864 bc_length = Bytecodes::length_at(method(), bcp);
1865 }
1866
1867 assert(bc_length != 0, "impossible bytecode length");
1868
1869 switch (c) {
1870 case Bytecodes::_ldc:
1871 {
1872 int cp_index = *(bcp + 1);
1873 int new_index = find_new_index(cp_index);
1874
1875 if (StressLdcRewrite && new_index == 0) {
1876 // If we are stressing ldc -> ldc_w rewriting, then we
1877 // always need a new_index value.
1878 new_index = cp_index;
1879 }
1880 if (new_index != 0) {
1881 // the original index is mapped so we have more work to do
1882 if (!StressLdcRewrite && new_index <= max_jubyte) {
1883 // The new value can still use ldc instead of ldc_w
1884 // unless we are trying to stress ldc -> ldc_w rewriting
1885 log_trace(redefine, class, constantpool)
1886 ("%s@" INTPTR_FORMAT " old=%d, new=%d", Bytecodes::name(c), p2i(bcp), cp_index, new_index);
1887 *(bcp + 1) = new_index;
1888 } else {
1889 log_trace(redefine, class, constantpool)
1890 ("%s->ldc_w@" INTPTR_FORMAT " old=%d, new=%d", Bytecodes::name(c), p2i(bcp), cp_index, new_index);
1891 // the new value needs ldc_w instead of ldc
1892 u_char inst_buffer[4]; // max instruction size is 4 bytes
1893 bcp = (address)inst_buffer;
1894 // construct new instruction sequence
1895 *bcp = Bytecodes::_ldc_w;
1896 bcp++;
1897 // Rewriter::rewrite_method() does not rewrite ldc -> ldc_w.
1898 // See comment below for difference between put_Java_u2()
1899 // and put_native_u2().
1900 Bytes::put_Java_u2(bcp, new_index);
1901
1902 Relocator rc(method, NULL /* no RelocatorListener needed */);
1903 methodHandle m;
1904 {
1905 PauseNoSafepointVerifier pnsv(&nsv);
1906
1907 // ldc is 2 bytes and ldc_w is 3 bytes
1908 m = rc.insert_space_at(bci, 3, inst_buffer, CHECK);
1909 }
1910
1911 // return the new method so that the caller can update
1912 // the containing class
1913 *new_method_p = method = m;
1914 // switch our bytecode processing loop from the old method
1915 // to the new method
1916 code_base = method->code_base();
1917 code_length = method->code_size();
1918 bcp = code_base + bci;
1919 c = (Bytecodes::Code)(*bcp);
1920 bc_length = Bytecodes::length_for(c);
1921 assert(bc_length != 0, "sanity check");
1922 } // end we need ldc_w instead of ldc
1923 } // end if there is a mapped index
1924 } break;
1925
1926 // these bytecodes have a two-byte constant pool index
1927 case Bytecodes::_anewarray : // fall through
1928 case Bytecodes::_checkcast : // fall through
1929 case Bytecodes::_getfield : // fall through
1930 case Bytecodes::_getstatic : // fall through
1931 case Bytecodes::_instanceof : // fall through
1932 case Bytecodes::_invokedynamic : // fall through
1933 case Bytecodes::_invokeinterface: // fall through
1934 case Bytecodes::_invokespecial : // fall through
1935 case Bytecodes::_invokestatic : // fall through
1936 case Bytecodes::_invokevirtual : // fall through
1937 case Bytecodes::_ldc_w : // fall through
1938 case Bytecodes::_ldc2_w : // fall through
1939 case Bytecodes::_multianewarray : // fall through
1940 case Bytecodes::_new : // fall through
1941 case Bytecodes::_putfield : // fall through
1942 case Bytecodes::_putstatic :
1943 {
1944 address p = bcp + 1;
1945 int cp_index = Bytes::get_Java_u2(p);
1946 int new_index = find_new_index(cp_index);
1947 if (new_index != 0) {
1948 // the original index is mapped so update w/ new value
1949 log_trace(redefine, class, constantpool)
1950 ("%s@" INTPTR_FORMAT " old=%d, new=%d", Bytecodes::name(c),p2i(bcp), cp_index, new_index);
1951 // Rewriter::rewrite_method() uses put_native_u2() in this
1952 // situation because it is reusing the constant pool index
1953 // location for a native index into the ConstantPoolCache.
1954 // Since we are updating the constant pool index prior to
1955 // verification and ConstantPoolCache initialization, we
1956 // need to keep the new index in Java byte order.
1957 Bytes::put_Java_u2(p, new_index);
1958 }
1959 } break;
1960 default:
1961 break;
1962 }
1963 } // end for each bytecode
1964
1965 // We also need to rewrite the parameter name indexes, if there is
1966 // method parameter data present
1967 if(method->has_method_parameters()) {
1968 const int len = method->method_parameters_length();
1969 MethodParametersElement* elem = method->method_parameters_start();
1970
1971 for (int i = 0; i < len; i++) {
1972 const u2 cp_index = elem[i].name_cp_index;
1973 const u2 new_cp_index = find_new_index(cp_index);
1974 if (new_cp_index != 0) {
1975 elem[i].name_cp_index = new_cp_index;
1976 }
1977 }
1978 }
1979 } // end rewrite_cp_refs_in_method()
1980
1981
1982 // Rewrite constant pool references in the class_annotations field.
1983 bool VM_RedefineClasses::rewrite_cp_refs_in_class_annotations(
1984 InstanceKlass* scratch_class, TRAPS) {
1985
1986 AnnotationArray* class_annotations = scratch_class->class_annotations();
1987 if (class_annotations == NULL || class_annotations->length() == 0) {
1988 // no class_annotations so nothing to do
1989 return true;
1990 }
1991
1992 log_debug(redefine, class, annotation)("class_annotations length=%d", class_annotations->length());
1993
1994 int byte_i = 0; // byte index into class_annotations
1995 return rewrite_cp_refs_in_annotations_typeArray(class_annotations, byte_i,
1996 THREAD);
1997 }
1998
1999
2000 // Rewrite constant pool references in an annotations typeArray. This
2001 // "structure" is adapted from the RuntimeVisibleAnnotations_attribute
2002 // that is described in section 4.8.15 of the 2nd-edition of the VM spec:
2003 //
2004 // annotations_typeArray {
2005 // u2 num_annotations;
2006 // annotation annotations[num_annotations];
2007 // }
2008 //
2009 bool VM_RedefineClasses::rewrite_cp_refs_in_annotations_typeArray(
2010 AnnotationArray* annotations_typeArray, int &byte_i_ref, TRAPS) {
2011
2012 if ((byte_i_ref + 2) > annotations_typeArray->length()) {
2013 // not enough room for num_annotations field
2014 log_debug(redefine, class, annotation)("length() is too small for num_annotations field");
2015 return false;
2016 }
2017
2018 u2 num_annotations = Bytes::get_Java_u2((address)
2019 annotations_typeArray->adr_at(byte_i_ref));
2020 byte_i_ref += 2;
2021
2022 log_debug(redefine, class, annotation)("num_annotations=%d", num_annotations);
2023
2024 int calc_num_annotations = 0;
2025 for (; calc_num_annotations < num_annotations; calc_num_annotations++) {
2026 if (!rewrite_cp_refs_in_annotation_struct(annotations_typeArray,
2027 byte_i_ref, THREAD)) {
2028 log_debug(redefine, class, annotation)("bad annotation_struct at %d", calc_num_annotations);
2029 // propagate failure back to caller
2030 return false;
2031 }
2032 }
2033 assert(num_annotations == calc_num_annotations, "sanity check");
2034
2035 return true;
2036 } // end rewrite_cp_refs_in_annotations_typeArray()
2037
2038
2039 // Rewrite constant pool references in the annotation struct portion of
2040 // an annotations_typeArray. This "structure" is from section 4.8.15 of
2041 // the 2nd-edition of the VM spec:
2042 //
2043 // struct annotation {
2044 // u2 type_index;
2045 // u2 num_element_value_pairs;
2046 // {
2047 // u2 element_name_index;
2048 // element_value value;
2049 // } element_value_pairs[num_element_value_pairs];
2050 // }
2051 //
2052 bool VM_RedefineClasses::rewrite_cp_refs_in_annotation_struct(
2053 AnnotationArray* annotations_typeArray, int &byte_i_ref, TRAPS) {
2054 if ((byte_i_ref + 2 + 2) > annotations_typeArray->length()) {
2055 // not enough room for smallest annotation_struct
2056 log_debug(redefine, class, annotation)("length() is too small for annotation_struct");
2057 return false;
2058 }
2059
2060 u2 type_index = rewrite_cp_ref_in_annotation_data(annotations_typeArray,
2061 byte_i_ref, "type_index", THREAD);
2062
2063 u2 num_element_value_pairs = Bytes::get_Java_u2((address)
2064 annotations_typeArray->adr_at(byte_i_ref));
2065 byte_i_ref += 2;
2066
2067 log_debug(redefine, class, annotation)
2068 ("type_index=%d num_element_value_pairs=%d", type_index, num_element_value_pairs);
2069
2070 int calc_num_element_value_pairs = 0;
2071 for (; calc_num_element_value_pairs < num_element_value_pairs;
2072 calc_num_element_value_pairs++) {
2073 if ((byte_i_ref + 2) > annotations_typeArray->length()) {
2074 // not enough room for another element_name_index, let alone
2075 // the rest of another component
2076 log_debug(redefine, class, annotation)("length() is too small for element_name_index");
2077 return false;
2078 }
2079
2080 u2 element_name_index = rewrite_cp_ref_in_annotation_data(
2081 annotations_typeArray, byte_i_ref,
2082 "element_name_index", THREAD);
2083
2084 log_debug(redefine, class, annotation)("element_name_index=%d", element_name_index);
2085
2086 if (!rewrite_cp_refs_in_element_value(annotations_typeArray,
2087 byte_i_ref, THREAD)) {
2088 log_debug(redefine, class, annotation)("bad element_value at %d", calc_num_element_value_pairs);
2089 // propagate failure back to caller
2090 return false;
2091 }
2092 } // end for each component
2093 assert(num_element_value_pairs == calc_num_element_value_pairs,
2094 "sanity check");
2095
2096 return true;
2097 } // end rewrite_cp_refs_in_annotation_struct()
2098
2099
2100 // Rewrite a constant pool reference at the current position in
2101 // annotations_typeArray if needed. Returns the original constant
2102 // pool reference if a rewrite was not needed or the new constant
2103 // pool reference if a rewrite was needed.
2104 u2 VM_RedefineClasses::rewrite_cp_ref_in_annotation_data(
2105 AnnotationArray* annotations_typeArray, int &byte_i_ref,
2106 const char * trace_mesg, TRAPS) {
2107
2108 address cp_index_addr = (address)
2109 annotations_typeArray->adr_at(byte_i_ref);
2110 u2 old_cp_index = Bytes::get_Java_u2(cp_index_addr);
2111 u2 new_cp_index = find_new_index(old_cp_index);
2112 if (new_cp_index != 0) {
2113 log_debug(redefine, class, annotation)("mapped old %s=%d", trace_mesg, old_cp_index);
2114 Bytes::put_Java_u2(cp_index_addr, new_cp_index);
2115 old_cp_index = new_cp_index;
2116 }
2117 byte_i_ref += 2;
2118 return old_cp_index;
2119 }
2120
2121
2122 // Rewrite constant pool references in the element_value portion of an
2123 // annotations_typeArray. This "structure" is from section 4.8.15.1 of
2124 // the 2nd-edition of the VM spec:
2125 //
2126 // struct element_value {
2127 // u1 tag;
2128 // union {
2129 // u2 const_value_index;
2130 // {
2131 // u2 type_name_index;
2132 // u2 const_name_index;
2133 // } enum_const_value;
2134 // u2 class_info_index;
2135 // annotation annotation_value;
2136 // struct {
2137 // u2 num_values;
2138 // element_value values[num_values];
2139 // } array_value;
2140 // } value;
2141 // }
2142 //
2143 bool VM_RedefineClasses::rewrite_cp_refs_in_element_value(
2144 AnnotationArray* annotations_typeArray, int &byte_i_ref, TRAPS) {
2145
2146 if ((byte_i_ref + 1) > annotations_typeArray->length()) {
2147 // not enough room for a tag let alone the rest of an element_value
2148 log_debug(redefine, class, annotation)("length() is too small for a tag");
2149 return false;
2150 }
2151
2152 u1 tag = annotations_typeArray->at(byte_i_ref);
2153 byte_i_ref++;
2154 log_debug(redefine, class, annotation)("tag='%c'", tag);
2155
2156 switch (tag) {
2157 // These BaseType tag values are from Table 4.2 in VM spec:
2158 case 'B': // byte
2159 case 'C': // char
2160 case 'D': // double
2161 case 'F': // float
2162 case 'I': // int
2163 case 'J': // long
2164 case 'S': // short
2165 case 'Z': // boolean
2166
2167 // The remaining tag values are from Table 4.8 in the 2nd-edition of
2168 // the VM spec:
2169 case 's':
2170 {
2171 // For the above tag values (including the BaseType values),
2172 // value.const_value_index is right union field.
2173
2174 if ((byte_i_ref + 2) > annotations_typeArray->length()) {
2175 // not enough room for a const_value_index
2176 log_debug(redefine, class, annotation)("length() is too small for a const_value_index");
2177 return false;
2178 }
2179
2180 u2 const_value_index = rewrite_cp_ref_in_annotation_data(
2181 annotations_typeArray, byte_i_ref,
2182 "const_value_index", THREAD);
2183
2184 log_debug(redefine, class, annotation)("const_value_index=%d", const_value_index);
2185 } break;
2186
2187 case 'e':
2188 {
2189 // for the above tag value, value.enum_const_value is right union field
2190
2191 if ((byte_i_ref + 4) > annotations_typeArray->length()) {
2192 // not enough room for a enum_const_value
2193 log_debug(redefine, class, annotation)("length() is too small for a enum_const_value");
2194 return false;
2195 }
2196
2197 u2 type_name_index = rewrite_cp_ref_in_annotation_data(
2198 annotations_typeArray, byte_i_ref,
2199 "type_name_index", THREAD);
2200
2201 u2 const_name_index = rewrite_cp_ref_in_annotation_data(
2202 annotations_typeArray, byte_i_ref,
2203 "const_name_index", THREAD);
2204
2205 log_debug(redefine, class, annotation)
2206 ("type_name_index=%d const_name_index=%d", type_name_index, const_name_index);
2207 } break;
2208
2209 case 'c':
2210 {
2211 // for the above tag value, value.class_info_index is right union field
2212
2213 if ((byte_i_ref + 2) > annotations_typeArray->length()) {
2214 // not enough room for a class_info_index
2215 log_debug(redefine, class, annotation)("length() is too small for a class_info_index");
2216 return false;
2217 }
2218
2219 u2 class_info_index = rewrite_cp_ref_in_annotation_data(
2220 annotations_typeArray, byte_i_ref,
2221 "class_info_index", THREAD);
2222
2223 log_debug(redefine, class, annotation)("class_info_index=%d", class_info_index);
2224 } break;
2225
2226 case '@':
2227 // For the above tag value, value.attr_value is the right union
2228 // field. This is a nested annotation.
2229 if (!rewrite_cp_refs_in_annotation_struct(annotations_typeArray,
2230 byte_i_ref, THREAD)) {
2231 // propagate failure back to caller
2232 return false;
2233 }
2234 break;
2235
2236 case '[':
2237 {
2238 if ((byte_i_ref + 2) > annotations_typeArray->length()) {
2239 // not enough room for a num_values field
2240 log_debug(redefine, class, annotation)("length() is too small for a num_values field");
2241 return false;
2242 }
2243
2244 // For the above tag value, value.array_value is the right union
2245 // field. This is an array of nested element_value.
2246 u2 num_values = Bytes::get_Java_u2((address)
2247 annotations_typeArray->adr_at(byte_i_ref));
2248 byte_i_ref += 2;
2249 log_debug(redefine, class, annotation)("num_values=%d", num_values);
2250
2251 int calc_num_values = 0;
2252 for (; calc_num_values < num_values; calc_num_values++) {
2253 if (!rewrite_cp_refs_in_element_value(
2254 annotations_typeArray, byte_i_ref, THREAD)) {
2255 log_debug(redefine, class, annotation)("bad nested element_value at %d", calc_num_values);
2256 // propagate failure back to caller
2257 return false;
2258 }
2259 }
2260 assert(num_values == calc_num_values, "sanity check");
2261 } break;
2262
2263 default:
2264 log_debug(redefine, class, annotation)("bad tag=0x%x", tag);
2265 return false;
2266 } // end decode tag field
2267
2268 return true;
2269 } // end rewrite_cp_refs_in_element_value()
2270
2271
2272 // Rewrite constant pool references in a fields_annotations field.
2273 bool VM_RedefineClasses::rewrite_cp_refs_in_fields_annotations(
2274 InstanceKlass* scratch_class, TRAPS) {
2275
2276 Array<AnnotationArray*>* fields_annotations = scratch_class->fields_annotations();
2277
2278 if (fields_annotations == NULL || fields_annotations->length() == 0) {
2279 // no fields_annotations so nothing to do
2280 return true;
2281 }
2282
2283 log_debug(redefine, class, annotation)("fields_annotations length=%d", fields_annotations->length());
2284
2285 for (int i = 0; i < fields_annotations->length(); i++) {
2286 AnnotationArray* field_annotations = fields_annotations->at(i);
2287 if (field_annotations == NULL || field_annotations->length() == 0) {
2288 // this field does not have any annotations so skip it
2289 continue;
2290 }
2291
2292 int byte_i = 0; // byte index into field_annotations
2293 if (!rewrite_cp_refs_in_annotations_typeArray(field_annotations, byte_i,
2294 THREAD)) {
2295 log_debug(redefine, class, annotation)("bad field_annotations at %d", i);
2296 // propagate failure back to caller
2297 return false;
2298 }
2299 }
2300
2301 return true;
2302 } // end rewrite_cp_refs_in_fields_annotations()
2303
2304
2305 // Rewrite constant pool references in a methods_annotations field.
2306 bool VM_RedefineClasses::rewrite_cp_refs_in_methods_annotations(
2307 InstanceKlass* scratch_class, TRAPS) {
2308
2309 for (int i = 0; i < scratch_class->methods()->length(); i++) {
2310 Method* m = scratch_class->methods()->at(i);
2311 AnnotationArray* method_annotations = m->constMethod()->method_annotations();
2312
2313 if (method_annotations == NULL || method_annotations->length() == 0) {
2314 // this method does not have any annotations so skip it
2315 continue;
2316 }
2317
2318 int byte_i = 0; // byte index into method_annotations
2319 if (!rewrite_cp_refs_in_annotations_typeArray(method_annotations, byte_i,
2320 THREAD)) {
2321 log_debug(redefine, class, annotation)("bad method_annotations at %d", i);
2322 // propagate failure back to caller
2323 return false;
2324 }
2325 }
2326
2327 return true;
2328 } // end rewrite_cp_refs_in_methods_annotations()
2329
2330
2331 // Rewrite constant pool references in a methods_parameter_annotations
2332 // field. This "structure" is adapted from the
2333 // RuntimeVisibleParameterAnnotations_attribute described in section
2334 // 4.8.17 of the 2nd-edition of the VM spec:
2335 //
2336 // methods_parameter_annotations_typeArray {
2337 // u1 num_parameters;
2338 // {
2339 // u2 num_annotations;
2340 // annotation annotations[num_annotations];
2341 // } parameter_annotations[num_parameters];
2342 // }
2343 //
2344 bool VM_RedefineClasses::rewrite_cp_refs_in_methods_parameter_annotations(
2345 InstanceKlass* scratch_class, TRAPS) {
2346
2347 for (int i = 0; i < scratch_class->methods()->length(); i++) {
2348 Method* m = scratch_class->methods()->at(i);
2349 AnnotationArray* method_parameter_annotations = m->constMethod()->parameter_annotations();
2350 if (method_parameter_annotations == NULL
2351 || method_parameter_annotations->length() == 0) {
2352 // this method does not have any parameter annotations so skip it
2353 continue;
2354 }
2355
2356 if (method_parameter_annotations->length() < 1) {
2357 // not enough room for a num_parameters field
2358 log_debug(redefine, class, annotation)("length() is too small for a num_parameters field at %d", i);
2359 return false;
2360 }
2361
2362 int byte_i = 0; // byte index into method_parameter_annotations
2363
2364 u1 num_parameters = method_parameter_annotations->at(byte_i);
2365 byte_i++;
2366
2367 log_debug(redefine, class, annotation)("num_parameters=%d", num_parameters);
2368
2369 int calc_num_parameters = 0;
2370 for (; calc_num_parameters < num_parameters; calc_num_parameters++) {
2371 if (!rewrite_cp_refs_in_annotations_typeArray(
2372 method_parameter_annotations, byte_i, THREAD)) {
2373 log_debug(redefine, class, annotation)("bad method_parameter_annotations at %d", calc_num_parameters);
2374 // propagate failure back to caller
2375 return false;
2376 }
2377 }
2378 assert(num_parameters == calc_num_parameters, "sanity check");
2379 }
2380
2381 return true;
2382 } // end rewrite_cp_refs_in_methods_parameter_annotations()
2383
2384
2385 // Rewrite constant pool references in a methods_default_annotations
2386 // field. This "structure" is adapted from the AnnotationDefault_attribute
2387 // that is described in section 4.8.19 of the 2nd-edition of the VM spec:
2388 //
2389 // methods_default_annotations_typeArray {
2390 // element_value default_value;
2391 // }
2392 //
2393 bool VM_RedefineClasses::rewrite_cp_refs_in_methods_default_annotations(
2394 InstanceKlass* scratch_class, TRAPS) {
2395
2396 for (int i = 0; i < scratch_class->methods()->length(); i++) {
2397 Method* m = scratch_class->methods()->at(i);
2398 AnnotationArray* method_default_annotations = m->constMethod()->default_annotations();
2399 if (method_default_annotations == NULL
2400 || method_default_annotations->length() == 0) {
2401 // this method does not have any default annotations so skip it
2402 continue;
2403 }
2404
2405 int byte_i = 0; // byte index into method_default_annotations
2406
2407 if (!rewrite_cp_refs_in_element_value(
2408 method_default_annotations, byte_i, THREAD)) {
2409 log_debug(redefine, class, annotation)("bad default element_value at %d", i);
2410 // propagate failure back to caller
2411 return false;
2412 }
2413 }
2414
2415 return true;
2416 } // end rewrite_cp_refs_in_methods_default_annotations()
2417
2418
2419 // Rewrite constant pool references in a class_type_annotations field.
2420 bool VM_RedefineClasses::rewrite_cp_refs_in_class_type_annotations(
2421 InstanceKlass* scratch_class, TRAPS) {
2422
2423 AnnotationArray* class_type_annotations = scratch_class->class_type_annotations();
2424 if (class_type_annotations == NULL || class_type_annotations->length() == 0) {
2425 // no class_type_annotations so nothing to do
2426 return true;
2427 }
2428
2429 log_debug(redefine, class, annotation)("class_type_annotations length=%d", class_type_annotations->length());
2430
2431 int byte_i = 0; // byte index into class_type_annotations
2432 return rewrite_cp_refs_in_type_annotations_typeArray(class_type_annotations,
2433 byte_i, "ClassFile", THREAD);
2434 } // end rewrite_cp_refs_in_class_type_annotations()
2435
2436
2437 // Rewrite constant pool references in a fields_type_annotations field.
2438 bool VM_RedefineClasses::rewrite_cp_refs_in_fields_type_annotations(
2439 InstanceKlass* scratch_class, TRAPS) {
2440
2441 Array<AnnotationArray*>* fields_type_annotations = scratch_class->fields_type_annotations();
2442 if (fields_type_annotations == NULL || fields_type_annotations->length() == 0) {
2443 // no fields_type_annotations so nothing to do
2444 return true;
2445 }
2446
2447 log_debug(redefine, class, annotation)("fields_type_annotations length=%d", fields_type_annotations->length());
2448
2449 for (int i = 0; i < fields_type_annotations->length(); i++) {
2450 AnnotationArray* field_type_annotations = fields_type_annotations->at(i);
2451 if (field_type_annotations == NULL || field_type_annotations->length() == 0) {
2452 // this field does not have any annotations so skip it
2453 continue;
2454 }
2455
2456 int byte_i = 0; // byte index into field_type_annotations
2457 if (!rewrite_cp_refs_in_type_annotations_typeArray(field_type_annotations,
2458 byte_i, "field_info", THREAD)) {
2459 log_debug(redefine, class, annotation)("bad field_type_annotations at %d", i);
2460 // propagate failure back to caller
2461 return false;
2462 }
2463 }
2464
2465 return true;
2466 } // end rewrite_cp_refs_in_fields_type_annotations()
2467
2468
2469 // Rewrite constant pool references in a methods_type_annotations field.
2470 bool VM_RedefineClasses::rewrite_cp_refs_in_methods_type_annotations(
2471 InstanceKlass* scratch_class, TRAPS) {
2472
2473 for (int i = 0; i < scratch_class->methods()->length(); i++) {
2474 Method* m = scratch_class->methods()->at(i);
2475 AnnotationArray* method_type_annotations = m->constMethod()->type_annotations();
2476
2477 if (method_type_annotations == NULL || method_type_annotations->length() == 0) {
2478 // this method does not have any annotations so skip it
2479 continue;
2480 }
2481
2482 log_debug(redefine, class, annotation)("methods type_annotations length=%d", method_type_annotations->length());
2483
2484 int byte_i = 0; // byte index into method_type_annotations
2485 if (!rewrite_cp_refs_in_type_annotations_typeArray(method_type_annotations,
2486 byte_i, "method_info", THREAD)) {
2487 log_debug(redefine, class, annotation)("bad method_type_annotations at %d", i);
2488 // propagate failure back to caller
2489 return false;
2490 }
2491 }
2492
2493 return true;
2494 } // end rewrite_cp_refs_in_methods_type_annotations()
2495
2496
2497 // Rewrite constant pool references in a type_annotations
2498 // field. This "structure" is adapted from the
2499 // RuntimeVisibleTypeAnnotations_attribute described in
2500 // section 4.7.20 of the Java SE 8 Edition of the VM spec:
2501 //
2502 // type_annotations_typeArray {
2503 // u2 num_annotations;
2504 // type_annotation annotations[num_annotations];
2505 // }
2506 //
2507 bool VM_RedefineClasses::rewrite_cp_refs_in_type_annotations_typeArray(
2508 AnnotationArray* type_annotations_typeArray, int &byte_i_ref,
2509 const char * location_mesg, TRAPS) {
2510
2511 if ((byte_i_ref + 2) > type_annotations_typeArray->length()) {
2512 // not enough room for num_annotations field
2513 log_debug(redefine, class, annotation)("length() is too small for num_annotations field");
2514 return false;
2515 }
2516
2517 u2 num_annotations = Bytes::get_Java_u2((address)
2518 type_annotations_typeArray->adr_at(byte_i_ref));
2519 byte_i_ref += 2;
2520
2521 log_debug(redefine, class, annotation)("num_type_annotations=%d", num_annotations);
2522
2523 int calc_num_annotations = 0;
2524 for (; calc_num_annotations < num_annotations; calc_num_annotations++) {
2525 if (!rewrite_cp_refs_in_type_annotation_struct(type_annotations_typeArray,
2526 byte_i_ref, location_mesg, THREAD)) {
2527 log_debug(redefine, class, annotation)("bad type_annotation_struct at %d", calc_num_annotations);
2528 // propagate failure back to caller
2529 return false;
2530 }
2531 }
2532 assert(num_annotations == calc_num_annotations, "sanity check");
2533
2534 if (byte_i_ref != type_annotations_typeArray->length()) {
2535 log_debug(redefine, class, annotation)
2536 ("read wrong amount of bytes at end of processing type_annotations_typeArray (%d of %d bytes were read)",
2537 byte_i_ref, type_annotations_typeArray->length());
2538 return false;
2539 }
2540
2541 return true;
2542 } // end rewrite_cp_refs_in_type_annotations_typeArray()
2543
2544
2545 // Rewrite constant pool references in a type_annotation
2546 // field. This "structure" is adapted from the
2547 // RuntimeVisibleTypeAnnotations_attribute described in
2548 // section 4.7.20 of the Java SE 8 Edition of the VM spec:
2549 //
2550 // type_annotation {
2551 // u1 target_type;
2552 // union {
2553 // type_parameter_target;
2554 // supertype_target;
2555 // type_parameter_bound_target;
2556 // empty_target;
2557 // method_formal_parameter_target;
2558 // throws_target;
2559 // localvar_target;
2560 // catch_target;
2561 // offset_target;
2562 // type_argument_target;
2563 // } target_info;
2564 // type_path target_path;
2565 // annotation anno;
2566 // }
2567 //
2568 bool VM_RedefineClasses::rewrite_cp_refs_in_type_annotation_struct(
2569 AnnotationArray* type_annotations_typeArray, int &byte_i_ref,
2570 const char * location_mesg, TRAPS) {
2571
2572 if (!skip_type_annotation_target(type_annotations_typeArray,
2573 byte_i_ref, location_mesg, THREAD)) {
2574 return false;
2575 }
2576
2577 if (!skip_type_annotation_type_path(type_annotations_typeArray,
2578 byte_i_ref, THREAD)) {
2579 return false;
2580 }
2581
2582 if (!rewrite_cp_refs_in_annotation_struct(type_annotations_typeArray,
2583 byte_i_ref, THREAD)) {
2584 return false;
2585 }
2586
2587 return true;
2588 } // end rewrite_cp_refs_in_type_annotation_struct()
2589
2590
2591 // Read, verify and skip over the target_type and target_info part
2592 // so that rewriting can continue in the later parts of the struct.
2593 //
2594 // u1 target_type;
2595 // union {
2596 // type_parameter_target;
2597 // supertype_target;
2598 // type_parameter_bound_target;
2599 // empty_target;
2600 // method_formal_parameter_target;
2601 // throws_target;
2602 // localvar_target;
2603 // catch_target;
2604 // offset_target;
2605 // type_argument_target;
2606 // } target_info;
2607 //
2608 bool VM_RedefineClasses::skip_type_annotation_target(
2609 AnnotationArray* type_annotations_typeArray, int &byte_i_ref,
2610 const char * location_mesg, TRAPS) {
2611
2612 if ((byte_i_ref + 1) > type_annotations_typeArray->length()) {
2613 // not enough room for a target_type let alone the rest of a type_annotation
2614 log_debug(redefine, class, annotation)("length() is too small for a target_type");
2615 return false;
2616 }
2617
2618 u1 target_type = type_annotations_typeArray->at(byte_i_ref);
2619 byte_i_ref += 1;
2620 log_debug(redefine, class, annotation)("target_type=0x%.2x", target_type);
2621 log_debug(redefine, class, annotation)("location=%s", location_mesg);
2622
2623 // Skip over target_info
2624 switch (target_type) {
2625 case 0x00:
2626 // kind: type parameter declaration of generic class or interface
2627 // location: ClassFile
2628 case 0x01:
2629 // kind: type parameter declaration of generic method or constructor
2630 // location: method_info
2631
2632 {
2633 // struct:
2634 // type_parameter_target {
2635 // u1 type_parameter_index;
2636 // }
2637 //
2638 if ((byte_i_ref + 1) > type_annotations_typeArray->length()) {
2639 log_debug(redefine, class, annotation)("length() is too small for a type_parameter_target");
2640 return false;
2641 }
2642
2643 u1 type_parameter_index = type_annotations_typeArray->at(byte_i_ref);
2644 byte_i_ref += 1;
2645
2646 log_debug(redefine, class, annotation)("type_parameter_target: type_parameter_index=%d", type_parameter_index);
2647 } break;
2648
2649 case 0x10:
2650 // kind: type in extends clause of class or interface declaration
2651 // (including the direct superclass of an unsafe anonymous class declaration),
2652 // or in implements clause of interface declaration
2653 // location: ClassFile
2654
2655 {
2656 // struct:
2657 // supertype_target {
2658 // u2 supertype_index;
2659 // }
2660 //
2661 if ((byte_i_ref + 2) > type_annotations_typeArray->length()) {
2662 log_debug(redefine, class, annotation)("length() is too small for a supertype_target");
2663 return false;
2664 }
2665
2666 u2 supertype_index = Bytes::get_Java_u2((address)
2667 type_annotations_typeArray->adr_at(byte_i_ref));
2668 byte_i_ref += 2;
2669
2670 log_debug(redefine, class, annotation)("supertype_target: supertype_index=%d", supertype_index);
2671 } break;
2672
2673 case 0x11:
2674 // kind: type in bound of type parameter declaration of generic class or interface
2675 // location: ClassFile
2676 case 0x12:
2677 // kind: type in bound of type parameter declaration of generic method or constructor
2678 // location: method_info
2679
2680 {
2681 // struct:
2682 // type_parameter_bound_target {
2683 // u1 type_parameter_index;
2684 // u1 bound_index;
2685 // }
2686 //
2687 if ((byte_i_ref + 2) > type_annotations_typeArray->length()) {
2688 log_debug(redefine, class, annotation)("length() is too small for a type_parameter_bound_target");
2689 return false;
2690 }
2691
2692 u1 type_parameter_index = type_annotations_typeArray->at(byte_i_ref);
2693 byte_i_ref += 1;
2694 u1 bound_index = type_annotations_typeArray->at(byte_i_ref);
2695 byte_i_ref += 1;
2696
2697 log_debug(redefine, class, annotation)
2698 ("type_parameter_bound_target: type_parameter_index=%d, bound_index=%d", type_parameter_index, bound_index);
2699 } break;
2700
2701 case 0x13:
2702 // kind: type in field declaration
2703 // location: field_info
2704 case 0x14:
2705 // kind: return type of method, or type of newly constructed object
2706 // location: method_info
2707 case 0x15:
2708 // kind: receiver type of method or constructor
2709 // location: method_info
2710
2711 {
2712 // struct:
2713 // empty_target {
2714 // }
2715 //
2716 log_debug(redefine, class, annotation)("empty_target");
2717 } break;
2718
2719 case 0x16:
2720 // kind: type in formal parameter declaration of method, constructor, or lambda expression
2721 // location: method_info
2722
2723 {
2724 // struct:
2725 // formal_parameter_target {
2726 // u1 formal_parameter_index;
2727 // }
2728 //
2729 if ((byte_i_ref + 1) > type_annotations_typeArray->length()) {
2730 log_debug(redefine, class, annotation)("length() is too small for a formal_parameter_target");
2731 return false;
2732 }
2733
2734 u1 formal_parameter_index = type_annotations_typeArray->at(byte_i_ref);
2735 byte_i_ref += 1;
2736
2737 log_debug(redefine, class, annotation)
2738 ("formal_parameter_target: formal_parameter_index=%d", formal_parameter_index);
2739 } break;
2740
2741 case 0x17:
2742 // kind: type in throws clause of method or constructor
2743 // location: method_info
2744
2745 {
2746 // struct:
2747 // throws_target {
2748 // u2 throws_type_index
2749 // }
2750 //
2751 if ((byte_i_ref + 2) > type_annotations_typeArray->length()) {
2752 log_debug(redefine, class, annotation)("length() is too small for a throws_target");
2753 return false;
2754 }
2755
2756 u2 throws_type_index = Bytes::get_Java_u2((address)
2757 type_annotations_typeArray->adr_at(byte_i_ref));
2758 byte_i_ref += 2;
2759
2760 log_debug(redefine, class, annotation)("throws_target: throws_type_index=%d", throws_type_index);
2761 } break;
2762
2763 case 0x40:
2764 // kind: type in local variable declaration
2765 // location: Code
2766 case 0x41:
2767 // kind: type in resource variable declaration
2768 // location: Code
2769
2770 {
2771 // struct:
2772 // localvar_target {
2773 // u2 table_length;
2774 // struct {
2775 // u2 start_pc;
2776 // u2 length;
2777 // u2 index;
2778 // } table[table_length];
2779 // }
2780 //
2781 if ((byte_i_ref + 2) > type_annotations_typeArray->length()) {
2782 // not enough room for a table_length let alone the rest of a localvar_target
2783 log_debug(redefine, class, annotation)("length() is too small for a localvar_target table_length");
2784 return false;
2785 }
2786
2787 u2 table_length = Bytes::get_Java_u2((address)
2788 type_annotations_typeArray->adr_at(byte_i_ref));
2789 byte_i_ref += 2;
2790
2791 log_debug(redefine, class, annotation)("localvar_target: table_length=%d", table_length);
2792
2793 int table_struct_size = 2 + 2 + 2; // 3 u2 variables per table entry
2794 int table_size = table_length * table_struct_size;
2795
2796 if ((byte_i_ref + table_size) > type_annotations_typeArray->length()) {
2797 // not enough room for a table
2798 log_debug(redefine, class, annotation)("length() is too small for a table array of length %d", table_length);
2799 return false;
2800 }
2801
2802 // Skip over table
2803 byte_i_ref += table_size;
2804 } break;
2805
2806 case 0x42:
2807 // kind: type in exception parameter declaration
2808 // location: Code
2809
2810 {
2811 // struct:
2812 // catch_target {
2813 // u2 exception_table_index;
2814 // }
2815 //
2816 if ((byte_i_ref + 2) > type_annotations_typeArray->length()) {
2817 log_debug(redefine, class, annotation)("length() is too small for a catch_target");
2818 return false;
2819 }
2820
2821 u2 exception_table_index = Bytes::get_Java_u2((address)
2822 type_annotations_typeArray->adr_at(byte_i_ref));
2823 byte_i_ref += 2;
2824
2825 log_debug(redefine, class, annotation)("catch_target: exception_table_index=%d", exception_table_index);
2826 } break;
2827
2828 case 0x43:
2829 // kind: type in instanceof expression
2830 // location: Code
2831 case 0x44:
2832 // kind: type in new expression
2833 // location: Code
2834 case 0x45:
2835 // kind: type in method reference expression using ::new
2836 // location: Code
2837 case 0x46:
2838 // kind: type in method reference expression using ::Identifier
2839 // location: Code
2840
2841 {
2842 // struct:
2843 // offset_target {
2844 // u2 offset;
2845 // }
2846 //
2847 if ((byte_i_ref + 2) > type_annotations_typeArray->length()) {
2848 log_debug(redefine, class, annotation)("length() is too small for a offset_target");
2849 return false;
2850 }
2851
2852 u2 offset = Bytes::get_Java_u2((address)
2853 type_annotations_typeArray->adr_at(byte_i_ref));
2854 byte_i_ref += 2;
2855
2856 log_debug(redefine, class, annotation)("offset_target: offset=%d", offset);
2857 } break;
2858
2859 case 0x47:
2860 // kind: type in cast expression
2861 // location: Code
2862 case 0x48:
2863 // kind: type argument for generic constructor in new expression or
2864 // explicit constructor invocation statement
2865 // location: Code
2866 case 0x49:
2867 // kind: type argument for generic method in method invocation expression
2868 // location: Code
2869 case 0x4A:
2870 // kind: type argument for generic constructor in method reference expression using ::new
2871 // location: Code
2872 case 0x4B:
2873 // kind: type argument for generic method in method reference expression using ::Identifier
2874 // location: Code
2875
2876 {
2877 // struct:
2878 // type_argument_target {
2879 // u2 offset;
2880 // u1 type_argument_index;
2881 // }
2882 //
2883 if ((byte_i_ref + 3) > type_annotations_typeArray->length()) {
2884 log_debug(redefine, class, annotation)("length() is too small for a type_argument_target");
2885 return false;
2886 }
2887
2888 u2 offset = Bytes::get_Java_u2((address)
2889 type_annotations_typeArray->adr_at(byte_i_ref));
2890 byte_i_ref += 2;
2891 u1 type_argument_index = type_annotations_typeArray->at(byte_i_ref);
2892 byte_i_ref += 1;
2893
2894 log_debug(redefine, class, annotation)
2895 ("type_argument_target: offset=%d, type_argument_index=%d", offset, type_argument_index);
2896 } break;
2897
2898 default:
2899 log_debug(redefine, class, annotation)("unknown target_type");
2900 #ifdef ASSERT
2901 ShouldNotReachHere();
2902 #endif
2903 return false;
2904 }
2905
2906 return true;
2907 } // end skip_type_annotation_target()
2908
2909
2910 // Read, verify and skip over the type_path part so that rewriting
2911 // can continue in the later parts of the struct.
2912 //
2913 // type_path {
2914 // u1 path_length;
2915 // {
2916 // u1 type_path_kind;
2917 // u1 type_argument_index;
2918 // } path[path_length];
2919 // }
2920 //
2921 bool VM_RedefineClasses::skip_type_annotation_type_path(
2922 AnnotationArray* type_annotations_typeArray, int &byte_i_ref, TRAPS) {
2923
2924 if ((byte_i_ref + 1) > type_annotations_typeArray->length()) {
2925 // not enough room for a path_length let alone the rest of the type_path
2926 log_debug(redefine, class, annotation)("length() is too small for a type_path");
2927 return false;
2928 }
2929
2930 u1 path_length = type_annotations_typeArray->at(byte_i_ref);
2931 byte_i_ref += 1;
2932
2933 log_debug(redefine, class, annotation)("type_path: path_length=%d", path_length);
2934
2935 int calc_path_length = 0;
2936 for (; calc_path_length < path_length; calc_path_length++) {
2937 if ((byte_i_ref + 1 + 1) > type_annotations_typeArray->length()) {
2938 // not enough room for a path
2939 log_debug(redefine, class, annotation)
2940 ("length() is too small for path entry %d of %d", calc_path_length, path_length);
2941 return false;
2942 }
2943
2944 u1 type_path_kind = type_annotations_typeArray->at(byte_i_ref);
2945 byte_i_ref += 1;
2946 u1 type_argument_index = type_annotations_typeArray->at(byte_i_ref);
2947 byte_i_ref += 1;
2948
2949 log_debug(redefine, class, annotation)
2950 ("type_path: path[%d]: type_path_kind=%d, type_argument_index=%d",
2951 calc_path_length, type_path_kind, type_argument_index);
2952
2953 if (type_path_kind > 3 || (type_path_kind != 3 && type_argument_index != 0)) {
2954 // not enough room for a path
2955 log_debug(redefine, class, annotation)("inconsistent type_path values");
2956 return false;
2957 }
2958 }
2959 assert(path_length == calc_path_length, "sanity check");
2960
2961 return true;
2962 } // end skip_type_annotation_type_path()
2963
2964
2965 // Rewrite constant pool references in the method's stackmap table.
2966 // These "structures" are adapted from the StackMapTable_attribute that
2967 // is described in section 4.8.4 of the 6.0 version of the VM spec
2968 // (dated 2005.10.26):
2969 // file:///net/quincunx.sfbay/export/gbracha/ClassFile-Java6.pdf
2970 //
2971 // stack_map {
2972 // u2 number_of_entries;
2973 // stack_map_frame entries[number_of_entries];
2974 // }
2975 //
2976 void VM_RedefineClasses::rewrite_cp_refs_in_stack_map_table(
2977 const methodHandle& method, TRAPS) {
2978
2979 if (!method->has_stackmap_table()) {
2980 return;
2981 }
2982
2983 AnnotationArray* stackmap_data = method->stackmap_data();
2984 address stackmap_p = (address)stackmap_data->adr_at(0);
2985 address stackmap_end = stackmap_p + stackmap_data->length();
2986
2987 assert(stackmap_p + 2 <= stackmap_end, "no room for number_of_entries");
2988 u2 number_of_entries = Bytes::get_Java_u2(stackmap_p);
2989 stackmap_p += 2;
2990
2991 log_debug(redefine, class, stackmap)("number_of_entries=%u", number_of_entries);
2992
2993 // walk through each stack_map_frame
2994 u2 calc_number_of_entries = 0;
2995 for (; calc_number_of_entries < number_of_entries; calc_number_of_entries++) {
2996 // The stack_map_frame structure is a u1 frame_type followed by
2997 // 0 or more bytes of data:
2998 //
2999 // union stack_map_frame {
3000 // same_frame;
3001 // same_locals_1_stack_item_frame;
3002 // same_locals_1_stack_item_frame_extended;
3003 // chop_frame;
3004 // same_frame_extended;
3005 // append_frame;
3006 // full_frame;
3007 // }
3008
3009 assert(stackmap_p + 1 <= stackmap_end, "no room for frame_type");
3010 u1 frame_type = *stackmap_p;
3011 stackmap_p++;
3012
3013 // same_frame {
3014 // u1 frame_type = SAME; /* 0-63 */
3015 // }
3016 if (frame_type <= 63) {
3017 // nothing more to do for same_frame
3018 }
3019
3020 // same_locals_1_stack_item_frame {
3021 // u1 frame_type = SAME_LOCALS_1_STACK_ITEM; /* 64-127 */
3022 // verification_type_info stack[1];
3023 // }
3024 else if (frame_type >= 64 && frame_type <= 127) {
3025 rewrite_cp_refs_in_verification_type_info(stackmap_p, stackmap_end,
3026 calc_number_of_entries, frame_type, THREAD);
3027 }
3028
3029 // reserved for future use
3030 else if (frame_type >= 128 && frame_type <= 246) {
3031 // nothing more to do for reserved frame_types
3032 }
3033
3034 // same_locals_1_stack_item_frame_extended {
3035 // u1 frame_type = SAME_LOCALS_1_STACK_ITEM_EXTENDED; /* 247 */
3036 // u2 offset_delta;
3037 // verification_type_info stack[1];
3038 // }
3039 else if (frame_type == 247) {
3040 stackmap_p += 2;
3041 rewrite_cp_refs_in_verification_type_info(stackmap_p, stackmap_end,
3042 calc_number_of_entries, frame_type, THREAD);
3043 }
3044
3045 // chop_frame {
3046 // u1 frame_type = CHOP; /* 248-250 */
3047 // u2 offset_delta;
3048 // }
3049 else if (frame_type >= 248 && frame_type <= 250) {
3050 stackmap_p += 2;
3051 }
3052
3053 // same_frame_extended {
3054 // u1 frame_type = SAME_FRAME_EXTENDED; /* 251*/
3055 // u2 offset_delta;
3056 // }
3057 else if (frame_type == 251) {
3058 stackmap_p += 2;
3059 }
3060
3061 // append_frame {
3062 // u1 frame_type = APPEND; /* 252-254 */
3063 // u2 offset_delta;
3064 // verification_type_info locals[frame_type - 251];
3065 // }
3066 else if (frame_type >= 252 && frame_type <= 254) {
3067 assert(stackmap_p + 2 <= stackmap_end,
3068 "no room for offset_delta");
3069 stackmap_p += 2;
3070 u1 len = frame_type - 251;
3071 for (u1 i = 0; i < len; i++) {
3072 rewrite_cp_refs_in_verification_type_info(stackmap_p, stackmap_end,
3073 calc_number_of_entries, frame_type, THREAD);
3074 }
3075 }
3076
3077 // full_frame {
3078 // u1 frame_type = FULL_FRAME; /* 255 */
3079 // u2 offset_delta;
3080 // u2 number_of_locals;
3081 // verification_type_info locals[number_of_locals];
3082 // u2 number_of_stack_items;
3083 // verification_type_info stack[number_of_stack_items];
3084 // }
3085 else if (frame_type == 255) {
3086 assert(stackmap_p + 2 + 2 <= stackmap_end,
3087 "no room for smallest full_frame");
3088 stackmap_p += 2;
3089
3090 u2 number_of_locals = Bytes::get_Java_u2(stackmap_p);
3091 stackmap_p += 2;
3092
3093 for (u2 locals_i = 0; locals_i < number_of_locals; locals_i++) {
3094 rewrite_cp_refs_in_verification_type_info(stackmap_p, stackmap_end,
3095 calc_number_of_entries, frame_type, THREAD);
3096 }
3097
3098 // Use the largest size for the number_of_stack_items, but only get
3099 // the right number of bytes.
3100 u2 number_of_stack_items = Bytes::get_Java_u2(stackmap_p);
3101 stackmap_p += 2;
3102
3103 for (u2 stack_i = 0; stack_i < number_of_stack_items; stack_i++) {
3104 rewrite_cp_refs_in_verification_type_info(stackmap_p, stackmap_end,
3105 calc_number_of_entries, frame_type, THREAD);
3106 }
3107 }
3108 } // end while there is a stack_map_frame
3109 assert(number_of_entries == calc_number_of_entries, "sanity check");
3110 } // end rewrite_cp_refs_in_stack_map_table()
3111
3112
3113 // Rewrite constant pool references in the verification type info
3114 // portion of the method's stackmap table. These "structures" are
3115 // adapted from the StackMapTable_attribute that is described in
3116 // section 4.8.4 of the 6.0 version of the VM spec (dated 2005.10.26):
3117 // file:///net/quincunx.sfbay/export/gbracha/ClassFile-Java6.pdf
3118 //
3119 // The verification_type_info structure is a u1 tag followed by 0 or
3120 // more bytes of data:
3121 //
3122 // union verification_type_info {
3123 // Top_variable_info;
3124 // Integer_variable_info;
3125 // Float_variable_info;
3126 // Long_variable_info;
3127 // Double_variable_info;
3128 // Null_variable_info;
3129 // UninitializedThis_variable_info;
3130 // Object_variable_info;
3131 // Uninitialized_variable_info;
3132 // }
3133 //
3134 void VM_RedefineClasses::rewrite_cp_refs_in_verification_type_info(
3135 address& stackmap_p_ref, address stackmap_end, u2 frame_i,
3136 u1 frame_type, TRAPS) {
3137
3138 assert(stackmap_p_ref + 1 <= stackmap_end, "no room for tag");
3139 u1 tag = *stackmap_p_ref;
3140 stackmap_p_ref++;
3141
3142 switch (tag) {
3143 // Top_variable_info {
3144 // u1 tag = ITEM_Top; /* 0 */
3145 // }
3146 // verificationType.hpp has zero as ITEM_Bogus instead of ITEM_Top
3147 case 0: // fall through
3148
3149 // Integer_variable_info {
3150 // u1 tag = ITEM_Integer; /* 1 */
3151 // }
3152 case ITEM_Integer: // fall through
3153
3154 // Float_variable_info {
3155 // u1 tag = ITEM_Float; /* 2 */
3156 // }
3157 case ITEM_Float: // fall through
3158
3159 // Double_variable_info {
3160 // u1 tag = ITEM_Double; /* 3 */
3161 // }
3162 case ITEM_Double: // fall through
3163
3164 // Long_variable_info {
3165 // u1 tag = ITEM_Long; /* 4 */
3166 // }
3167 case ITEM_Long: // fall through
3168
3169 // Null_variable_info {
3170 // u1 tag = ITEM_Null; /* 5 */
3171 // }
3172 case ITEM_Null: // fall through
3173
3174 // UninitializedThis_variable_info {
3175 // u1 tag = ITEM_UninitializedThis; /* 6 */
3176 // }
3177 case ITEM_UninitializedThis:
3178 // nothing more to do for the above tag types
3179 break;
3180
3181 // Object_variable_info {
3182 // u1 tag = ITEM_Object; /* 7 */
3183 // u2 cpool_index;
3184 // }
3185 case ITEM_Object:
3186 {
3187 assert(stackmap_p_ref + 2 <= stackmap_end, "no room for cpool_index");
3188 u2 cpool_index = Bytes::get_Java_u2(stackmap_p_ref);
3189 u2 new_cp_index = find_new_index(cpool_index);
3190 if (new_cp_index != 0) {
3191 log_debug(redefine, class, stackmap)("mapped old cpool_index=%d", cpool_index);
3192 Bytes::put_Java_u2(stackmap_p_ref, new_cp_index);
3193 cpool_index = new_cp_index;
3194 }
3195 stackmap_p_ref += 2;
3196
3197 log_debug(redefine, class, stackmap)
3198 ("frame_i=%u, frame_type=%u, cpool_index=%d", frame_i, frame_type, cpool_index);
3199 } break;
3200
3201 // Uninitialized_variable_info {
3202 // u1 tag = ITEM_Uninitialized; /* 8 */
3203 // u2 offset;
3204 // }
3205 case ITEM_Uninitialized:
3206 assert(stackmap_p_ref + 2 <= stackmap_end, "no room for offset");
3207 stackmap_p_ref += 2;
3208 break;
3209
3210 default:
3211 log_debug(redefine, class, stackmap)("frame_i=%u, frame_type=%u, bad tag=0x%x", frame_i, frame_type, tag);
3212 ShouldNotReachHere();
3213 break;
3214 } // end switch (tag)
3215 } // end rewrite_cp_refs_in_verification_type_info()
3216
3217
3218 // Change the constant pool associated with klass scratch_class to
3219 // scratch_cp. If shrink is true, then scratch_cp_length elements
3220 // are copied from scratch_cp to a smaller constant pool and the
3221 // smaller constant pool is associated with scratch_class.
3222 void VM_RedefineClasses::set_new_constant_pool(
3223 ClassLoaderData* loader_data,
3224 InstanceKlass* scratch_class, constantPoolHandle scratch_cp,
3225 int scratch_cp_length, TRAPS) {
3226 assert(scratch_cp->length() >= scratch_cp_length, "sanity check");
3227
3228 // scratch_cp is a merged constant pool and has enough space for a
3229 // worst case merge situation. We want to associate the minimum
3230 // sized constant pool with the klass to save space.
3231 ConstantPool* cp = ConstantPool::allocate(loader_data, scratch_cp_length, CHECK);
3232 constantPoolHandle smaller_cp(THREAD, cp);
3233
3234 // preserve version() value in the smaller copy
3235 int version = scratch_cp->version();
3236 assert(version != 0, "sanity check");
3237 smaller_cp->set_version(version);
3238
3239 // attach klass to new constant pool
3240 // reference to the cp holder is needed for copy_operands()
3241 smaller_cp->set_pool_holder(scratch_class);
3242
3243 scratch_cp->copy_cp_to(1, scratch_cp_length - 1, smaller_cp, 1, THREAD);
3244 if (HAS_PENDING_EXCEPTION) {
3245 // Exception is handled in the caller
3246 loader_data->add_to_deallocate_list(smaller_cp());
3247 return;
3248 }
3249 scratch_cp = smaller_cp;
3250
3251 // attach new constant pool to klass
3252 scratch_class->set_constants(scratch_cp());
3253 scratch_cp->initialize_unresolved_klasses(loader_data, CHECK);
3254
3255 int i; // for portability
3256
3257 // update each field in klass to use new constant pool indices as needed
3258 for (JavaFieldStream fs(scratch_class); !fs.done(); fs.next()) {
3259 jshort cur_index = fs.name_index();
3260 jshort new_index = find_new_index(cur_index);
3261 if (new_index != 0) {
3262 log_trace(redefine, class, constantpool)("field-name_index change: %d to %d", cur_index, new_index);
3263 fs.set_name_index(new_index);
3264 }
3265 cur_index = fs.signature_index();
3266 new_index = find_new_index(cur_index);
3267 if (new_index != 0) {
3268 log_trace(redefine, class, constantpool)("field-signature_index change: %d to %d", cur_index, new_index);
3269 fs.set_signature_index(new_index);
3270 }
3271 cur_index = fs.initval_index();
3272 new_index = find_new_index(cur_index);
3273 if (new_index != 0) {
3274 log_trace(redefine, class, constantpool)("field-initval_index change: %d to %d", cur_index, new_index);
3275 fs.set_initval_index(new_index);
3276 }
3277 cur_index = fs.generic_signature_index();
3278 new_index = find_new_index(cur_index);
3279 if (new_index != 0) {
3280 log_trace(redefine, class, constantpool)("field-generic_signature change: %d to %d", cur_index, new_index);
3281 fs.set_generic_signature_index(new_index);
3282 }
3283 } // end for each field
3284
3285 // Update constant pool indices in the inner classes info to use
3286 // new constant indices as needed. The inner classes info is a
3287 // quadruple:
3288 // (inner_class_info, outer_class_info, inner_name, inner_access_flags)
3289 InnerClassesIterator iter(scratch_class);
3290 for (; !iter.done(); iter.next()) {
3291 int cur_index = iter.inner_class_info_index();
3292 if (cur_index == 0) {
3293 continue; // JVM spec. allows null inner class refs so skip it
3294 }
3295 int new_index = find_new_index(cur_index);
3296 if (new_index != 0) {
3297 log_trace(redefine, class, constantpool)("inner_class_info change: %d to %d", cur_index, new_index);
3298 iter.set_inner_class_info_index(new_index);
3299 }
3300 cur_index = iter.outer_class_info_index();
3301 new_index = find_new_index(cur_index);
3302 if (new_index != 0) {
3303 log_trace(redefine, class, constantpool)("outer_class_info change: %d to %d", cur_index, new_index);
3304 iter.set_outer_class_info_index(new_index);
3305 }
3306 cur_index = iter.inner_name_index();
3307 new_index = find_new_index(cur_index);
3308 if (new_index != 0) {
3309 log_trace(redefine, class, constantpool)("inner_name change: %d to %d", cur_index, new_index);
3310 iter.set_inner_name_index(new_index);
3311 }
3312 } // end for each inner class
3313
3314 // Attach each method in klass to the new constant pool and update
3315 // to use new constant pool indices as needed:
3316 Array<Method*>* methods = scratch_class->methods();
3317 for (i = methods->length() - 1; i >= 0; i--) {
3318 methodHandle method(THREAD, methods->at(i));
3319 method->set_constants(scratch_cp());
3320
3321 int new_index = find_new_index(method->name_index());
3322 if (new_index != 0) {
3323 log_trace(redefine, class, constantpool)
3324 ("method-name_index change: %d to %d", method->name_index(), new_index);
3325 method->set_name_index(new_index);
3326 }
3327 new_index = find_new_index(method->signature_index());
3328 if (new_index != 0) {
3329 log_trace(redefine, class, constantpool)
3330 ("method-signature_index change: %d to %d", method->signature_index(), new_index);
3331 method->set_signature_index(new_index);
3332 }
3333 new_index = find_new_index(method->generic_signature_index());
3334 if (new_index != 0) {
3335 log_trace(redefine, class, constantpool)
3336 ("method-generic_signature_index change: %d to %d", method->generic_signature_index(), new_index);
3337 method->set_generic_signature_index(new_index);
3338 }
3339
3340 // Update constant pool indices in the method's checked exception
3341 // table to use new constant indices as needed.
3342 int cext_length = method->checked_exceptions_length();
3343 if (cext_length > 0) {
3344 CheckedExceptionElement * cext_table =
3345 method->checked_exceptions_start();
3346 for (int j = 0; j < cext_length; j++) {
3347 int cur_index = cext_table[j].class_cp_index;
3348 int new_index = find_new_index(cur_index);
3349 if (new_index != 0) {
3350 log_trace(redefine, class, constantpool)("cext-class_cp_index change: %d to %d", cur_index, new_index);
3351 cext_table[j].class_cp_index = (u2)new_index;
3352 }
3353 } // end for each checked exception table entry
3354 } // end if there are checked exception table entries
3355
3356 // Update each catch type index in the method's exception table
3357 // to use new constant pool indices as needed. The exception table
3358 // holds quadruple entries of the form:
3359 // (beg_bci, end_bci, handler_bci, klass_index)
3360
3361 ExceptionTable ex_table(method());
3362 int ext_length = ex_table.length();
3363
3364 for (int j = 0; j < ext_length; j ++) {
3365 int cur_index = ex_table.catch_type_index(j);
3366 int new_index = find_new_index(cur_index);
3367 if (new_index != 0) {
3368 log_trace(redefine, class, constantpool)("ext-klass_index change: %d to %d", cur_index, new_index);
3369 ex_table.set_catch_type_index(j, new_index);
3370 }
3371 } // end for each exception table entry
3372
3373 // Update constant pool indices in the method's local variable
3374 // table to use new constant indices as needed. The local variable
3375 // table hold sextuple entries of the form:
3376 // (start_pc, length, name_index, descriptor_index, signature_index, slot)
3377 int lvt_length = method->localvariable_table_length();
3378 if (lvt_length > 0) {
3379 LocalVariableTableElement * lv_table =
3380 method->localvariable_table_start();
3381 for (int j = 0; j < lvt_length; j++) {
3382 int cur_index = lv_table[j].name_cp_index;
3383 int new_index = find_new_index(cur_index);
3384 if (new_index != 0) {
3385 log_trace(redefine, class, constantpool)("lvt-name_cp_index change: %d to %d", cur_index, new_index);
3386 lv_table[j].name_cp_index = (u2)new_index;
3387 }
3388 cur_index = lv_table[j].descriptor_cp_index;
3389 new_index = find_new_index(cur_index);
3390 if (new_index != 0) {
3391 log_trace(redefine, class, constantpool)("lvt-descriptor_cp_index change: %d to %d", cur_index, new_index);
3392 lv_table[j].descriptor_cp_index = (u2)new_index;
3393 }
3394 cur_index = lv_table[j].signature_cp_index;
3395 new_index = find_new_index(cur_index);
3396 if (new_index != 0) {
3397 log_trace(redefine, class, constantpool)("lvt-signature_cp_index change: %d to %d", cur_index, new_index);
3398 lv_table[j].signature_cp_index = (u2)new_index;
3399 }
3400 } // end for each local variable table entry
3401 } // end if there are local variable table entries
3402
3403 rewrite_cp_refs_in_stack_map_table(method, THREAD);
3404 } // end for each method
3405 } // end set_new_constant_pool()
3406
3407
3408 // Unevolving classes may point to methods of the_class directly
3409 // from their constant pool caches, itables, and/or vtables. We
3410 // use the ClassLoaderDataGraph::classes_do() facility and this helper
3411 // to fix up these pointers.
3412
3413 // Adjust cpools and vtables closure
3414 void VM_RedefineClasses::AdjustCpoolCacheAndVtable::do_klass(Klass* k) {
3415
3416 // This is a very busy routine. We don't want too much tracing
3417 // printed out.
3418 bool trace_name_printed = false;
3419 InstanceKlass *the_class = InstanceKlass::cast(_the_class);
3420
3421 // If the class being redefined is java.lang.Object, we need to fix all
3422 // array class vtables also
3423 if (k->is_array_klass() && _the_class == SystemDictionary::Object_klass()) {
3424 k->vtable().adjust_method_entries(the_class, &trace_name_printed);
3425
3426 } else if (k->is_instance_klass()) {
3427 HandleMark hm(_thread);
3428 InstanceKlass *ik = InstanceKlass::cast(k);
3429
3430 // HotSpot specific optimization! HotSpot does not currently
3431 // support delegation from the bootstrap class loader to a
3432 // user-defined class loader. This means that if the bootstrap
3433 // class loader is the initiating class loader, then it will also
3434 // be the defining class loader. This also means that classes
3435 // loaded by the bootstrap class loader cannot refer to classes
3436 // loaded by a user-defined class loader. Note: a user-defined
3437 // class loader can delegate to the bootstrap class loader.
3438 //
3439 // If the current class being redefined has a user-defined class
3440 // loader as its defining class loader, then we can skip all
3441 // classes loaded by the bootstrap class loader.
3442 bool is_user_defined = (_the_class->class_loader() != NULL);
3443 if (is_user_defined && ik->class_loader() == NULL) {
3444 return;
3445 }
3446
3447 // Fix the vtable embedded in the_class and subclasses of the_class,
3448 // if one exists. We discard scratch_class and we don't keep an
3449 // InstanceKlass around to hold obsolete methods so we don't have
3450 // any other InstanceKlass embedded vtables to update. The vtable
3451 // holds the Method*s for virtual (but not final) methods.
3452 // Default methods, or concrete methods in interfaces are stored
3453 // in the vtable, so if an interface changes we need to check
3454 // adjust_method_entries() for every InstanceKlass, which will also
3455 // adjust the default method vtable indices.
3456 // We also need to adjust any default method entries that are
3457 // not yet in the vtable, because the vtable setup is in progress.
3458 // This must be done after we adjust the default_methods and
3459 // default_vtable_indices for methods already in the vtable.
3460 // If redefining Unsafe, walk all the vtables looking for entries.
3461 if (ik->vtable_length() > 0 && (_the_class->is_interface()
3462 || _the_class == SystemDictionary::internal_Unsafe_klass()
3463 || ik->is_subtype_of(_the_class))) {
3464 // ik->vtable() creates a wrapper object; rm cleans it up
3465 ResourceMark rm(_thread);
3466
3467 ik->vtable().adjust_method_entries(the_class, &trace_name_printed);
3468 ik->adjust_default_methods(the_class, &trace_name_printed);
3469 }
3470
3471 // If the current class has an itable and we are either redefining an
3472 // interface or if the current class is a subclass of the_class, then
3473 // we potentially have to fix the itable. If we are redefining an
3474 // interface, then we have to call adjust_method_entries() for
3475 // every InstanceKlass that has an itable since there isn't a
3476 // subclass relationship between an interface and an InstanceKlass.
3477 // If redefining Unsafe, walk all the itables looking for entries.
3478 if (ik->itable_length() > 0 && (_the_class->is_interface()
3479 || _the_class == SystemDictionary::internal_Unsafe_klass()
3480 || ik->is_subclass_of(_the_class))) {
3481 ResourceMark rm(_thread);
3482 ik->itable().adjust_method_entries(the_class, &trace_name_printed);
3483 }
3484
3485 // The constant pools in other classes (other_cp) can refer to
3486 // methods in the_class. We have to update method information in
3487 // other_cp's cache. If other_cp has a previous version, then we
3488 // have to repeat the process for each previous version. The
3489 // constant pool cache holds the Method*s for non-virtual
3490 // methods and for virtual, final methods.
3491 //
3492 // Special case: if the current class is the_class, then new_cp
3493 // has already been attached to the_class and old_cp has already
3494 // been added as a previous version. The new_cp doesn't have any
3495 // cached references to old methods so it doesn't need to be
3496 // updated. We can simply start with the previous version(s) in
3497 // that case.
3498 constantPoolHandle other_cp;
3499 ConstantPoolCache* cp_cache;
3500
3501 if (ik != _the_class) {
3502 // this klass' constant pool cache may need adjustment
3503 other_cp = constantPoolHandle(ik->constants());
3504 cp_cache = other_cp->cache();
3505 if (cp_cache != NULL) {
3506 cp_cache->adjust_method_entries(the_class, &trace_name_printed);
3507 }
3508 }
3509
3510 // the previous versions' constant pool caches may need adjustment
3511 for (InstanceKlass* pv_node = ik->previous_versions();
3512 pv_node != NULL;
3513 pv_node = pv_node->previous_versions()) {
3514 cp_cache = pv_node->constants()->cache();
3515 if (cp_cache != NULL) {
3516 cp_cache->adjust_method_entries(pv_node, &trace_name_printed);
3517 }
3518 }
3519 }
3520 }
3521
3522 // Clean method data for this class
3523 void VM_RedefineClasses::MethodDataCleaner::do_klass(Klass* k) {
3524 if (k->is_instance_klass()) {
3525 InstanceKlass *ik = InstanceKlass::cast(k);
3526 // Clean MethodData of this class's methods so they don't refer to
3527 // old methods that are no longer running.
3528 Array<Method*>* methods = ik->methods();
3529 int num_methods = methods->length();
3530 for (int index = 0; index < num_methods; ++index) {
3531 if (methods->at(index)->method_data() != NULL) {
3532 methods->at(index)->method_data()->clean_weak_method_links();
3533 }
3534 }
3535 }
3536 }
3537
3538 void VM_RedefineClasses::update_jmethod_ids() {
3539 for (int j = 0; j < _matching_methods_length; ++j) {
3540 Method* old_method = _matching_old_methods[j];
3541 jmethodID jmid = old_method->find_jmethod_id_or_null();
3542 if (jmid != NULL) {
3543 // There is a jmethodID, change it to point to the new method
3544 methodHandle new_method_h(_matching_new_methods[j]);
3545 Method::change_method_associated_with_jmethod_id(jmid, new_method_h());
3546 assert(Method::resolve_jmethod_id(jmid) == _matching_new_methods[j],
3547 "should be replaced");
3548 }
3549 }
3550 }
3551
3552 int VM_RedefineClasses::check_methods_and_mark_as_obsolete() {
3553 int emcp_method_count = 0;
3554 int obsolete_count = 0;
3555 int old_index = 0;
3556 for (int j = 0; j < _matching_methods_length; ++j, ++old_index) {
3557 Method* old_method = _matching_old_methods[j];
3558 Method* new_method = _matching_new_methods[j];
3559 Method* old_array_method;
3560
3561 // Maintain an old_index into the _old_methods array by skipping
3562 // deleted methods
3563 while ((old_array_method = _old_methods->at(old_index)) != old_method) {
3564 ++old_index;
3565 }
3566
3567 if (MethodComparator::methods_EMCP(old_method, new_method)) {
3568 // The EMCP definition from JSR-163 requires the bytecodes to be
3569 // the same with the exception of constant pool indices which may
3570 // differ. However, the constants referred to by those indices
3571 // must be the same.
3572 //
3573 // We use methods_EMCP() for comparison since constant pool
3574 // merging can remove duplicate constant pool entries that were
3575 // present in the old method and removed from the rewritten new
3576 // method. A faster binary comparison function would consider the
3577 // old and new methods to be different when they are actually
3578 // EMCP.
3579 //
3580 // The old and new methods are EMCP and you would think that we
3581 // could get rid of one of them here and now and save some space.
3582 // However, the concept of EMCP only considers the bytecodes and
3583 // the constant pool entries in the comparison. Other things,
3584 // e.g., the line number table (LNT) or the local variable table
3585 // (LVT) don't count in the comparison. So the new (and EMCP)
3586 // method can have a new LNT that we need so we can't just
3587 // overwrite the new method with the old method.
3588 //
3589 // When this routine is called, we have already attached the new
3590 // methods to the_class so the old methods are effectively
3591 // overwritten. However, if an old method is still executing,
3592 // then the old method cannot be collected until sometime after
3593 // the old method call has returned. So the overwriting of old
3594 // methods by new methods will save us space except for those
3595 // (hopefully few) old methods that are still executing.
3596 //
3597 // A method refers to a ConstMethod* and this presents another
3598 // possible avenue to space savings. The ConstMethod* in the
3599 // new method contains possibly new attributes (LNT, LVT, etc).
3600 // At first glance, it seems possible to save space by replacing
3601 // the ConstMethod* in the old method with the ConstMethod*
3602 // from the new method. The old and new methods would share the
3603 // same ConstMethod* and we would save the space occupied by
3604 // the old ConstMethod*. However, the ConstMethod* contains
3605 // a back reference to the containing method. Sharing the
3606 // ConstMethod* between two methods could lead to confusion in
3607 // the code that uses the back reference. This would lead to
3608 // brittle code that could be broken in non-obvious ways now or
3609 // in the future.
3610 //
3611 // Another possibility is to copy the ConstMethod* from the new
3612 // method to the old method and then overwrite the new method with
3613 // the old method. Since the ConstMethod* contains the bytecodes
3614 // for the method embedded in the oop, this option would change
3615 // the bytecodes out from under any threads executing the old
3616 // method and make the thread's bcp invalid. Since EMCP requires
3617 // that the bytecodes be the same modulo constant pool indices, it
3618 // is straight forward to compute the correct new bcp in the new
3619 // ConstMethod* from the old bcp in the old ConstMethod*. The
3620 // time consuming part would be searching all the frames in all
3621 // of the threads to find all of the calls to the old method.
3622 //
3623 // It looks like we will have to live with the limited savings
3624 // that we get from effectively overwriting the old methods
3625 // when the new methods are attached to the_class.
3626
3627 // Count number of methods that are EMCP. The method will be marked
3628 // old but not obsolete if it is EMCP.
3629 emcp_method_count++;
3630
3631 // An EMCP method is _not_ obsolete. An obsolete method has a
3632 // different jmethodID than the current method. An EMCP method
3633 // has the same jmethodID as the current method. Having the
3634 // same jmethodID for all EMCP versions of a method allows for
3635 // a consistent view of the EMCP methods regardless of which
3636 // EMCP method you happen to have in hand. For example, a
3637 // breakpoint set in one EMCP method will work for all EMCP
3638 // versions of the method including the current one.
3639 } else {
3640 // mark obsolete methods as such
3641 old_method->set_is_obsolete();
3642 obsolete_count++;
3643
3644 // obsolete methods need a unique idnum so they become new entries in
3645 // the jmethodID cache in InstanceKlass
3646 assert(old_method->method_idnum() == new_method->method_idnum(), "must match");
3647 u2 num = InstanceKlass::cast(_the_class)->next_method_idnum();
3648 if (num != ConstMethod::UNSET_IDNUM) {
3649 old_method->set_method_idnum(num);
3650 }
3651
3652 // With tracing we try not to "yack" too much. The position of
3653 // this trace assumes there are fewer obsolete methods than
3654 // EMCP methods.
3655 if (log_is_enabled(Trace, redefine, class, obsolete, mark)) {
3656 ResourceMark rm;
3657 log_trace(redefine, class, obsolete, mark)
3658 ("mark %s(%s) as obsolete", old_method->name()->as_C_string(), old_method->signature()->as_C_string());
3659 }
3660 }
3661 old_method->set_is_old();
3662 }
3663 for (int i = 0; i < _deleted_methods_length; ++i) {
3664 Method* old_method = _deleted_methods[i];
3665
3666 assert(!old_method->has_vtable_index(),
3667 "cannot delete methods with vtable entries");;
3668
3669 // Mark all deleted methods as old, obsolete and deleted
3670 old_method->set_is_deleted();
3671 old_method->set_is_old();
3672 old_method->set_is_obsolete();
3673 ++obsolete_count;
3674 // With tracing we try not to "yack" too much. The position of
3675 // this trace assumes there are fewer obsolete methods than
3676 // EMCP methods.
3677 if (log_is_enabled(Trace, redefine, class, obsolete, mark)) {
3678 ResourceMark rm;
3679 log_trace(redefine, class, obsolete, mark)
3680 ("mark deleted %s(%s) as obsolete", old_method->name()->as_C_string(), old_method->signature()->as_C_string());
3681 }
3682 }
3683 assert((emcp_method_count + obsolete_count) == _old_methods->length(),
3684 "sanity check");
3685 log_trace(redefine, class, obsolete, mark)("EMCP_cnt=%d, obsolete_cnt=%d", emcp_method_count, obsolete_count);
3686 return emcp_method_count;
3687 }
3688
3689 // This internal class transfers the native function registration from old methods
3690 // to new methods. It is designed to handle both the simple case of unchanged
3691 // native methods and the complex cases of native method prefixes being added and/or
3692 // removed.
3693 // It expects only to be used during the VM_RedefineClasses op (a safepoint).
3694 //
3695 // This class is used after the new methods have been installed in "the_class".
3696 //
3697 // So, for example, the following must be handled. Where 'm' is a method and
3698 // a number followed by an underscore is a prefix.
3699 //
3700 // Old Name New Name
3701 // Simple transfer to new method m -> m
3702 // Add prefix m -> 1_m
3703 // Remove prefix 1_m -> m
3704 // Simultaneous add of prefixes m -> 3_2_1_m
3705 // Simultaneous removal of prefixes 3_2_1_m -> m
3706 // Simultaneous add and remove 1_m -> 2_m
3707 // Same, caused by prefix removal only 3_2_1_m -> 3_2_m
3708 //
3709 class TransferNativeFunctionRegistration {
3710 private:
3711 InstanceKlass* the_class;
3712 int prefix_count;
3713 char** prefixes;
3714
3715 // Recursively search the binary tree of possibly prefixed method names.
3716 // Iteration could be used if all agents were well behaved. Full tree walk is
3717 // more resilent to agents not cleaning up intermediate methods.
3718 // Branch at each depth in the binary tree is:
3719 // (1) without the prefix.
3720 // (2) with the prefix.
3721 // where 'prefix' is the prefix at that 'depth' (first prefix, second prefix,...)
3722 Method* search_prefix_name_space(int depth, char* name_str, size_t name_len,
3723 Symbol* signature) {
3724 TempNewSymbol name_symbol = SymbolTable::probe(name_str, (int)name_len);
3725 if (name_symbol != NULL) {
3726 Method* method = the_class->lookup_method(name_symbol, signature);
3727 if (method != NULL) {
3728 // Even if prefixed, intermediate methods must exist.
3729 if (method->is_native()) {
3730 // Wahoo, we found a (possibly prefixed) version of the method, return it.
3731 return method;
3732 }
3733 if (depth < prefix_count) {
3734 // Try applying further prefixes (other than this one).
3735 method = search_prefix_name_space(depth+1, name_str, name_len, signature);
3736 if (method != NULL) {
3737 return method; // found
3738 }
3739
3740 // Try adding this prefix to the method name and see if it matches
3741 // another method name.
3742 char* prefix = prefixes[depth];
3743 size_t prefix_len = strlen(prefix);
3744 size_t trial_len = name_len + prefix_len;
3745 char* trial_name_str = NEW_RESOURCE_ARRAY(char, trial_len + 1);
3746 strcpy(trial_name_str, prefix);
3747 strcat(trial_name_str, name_str);
3748 method = search_prefix_name_space(depth+1, trial_name_str, trial_len,
3749 signature);
3750 if (method != NULL) {
3751 // If found along this branch, it was prefixed, mark as such
3752 method->set_is_prefixed_native();
3753 return method; // found
3754 }
3755 }
3756 }
3757 }
3758 return NULL; // This whole branch bore nothing
3759 }
3760
3761 // Return the method name with old prefixes stripped away.
3762 char* method_name_without_prefixes(Method* method) {
3763 Symbol* name = method->name();
3764 char* name_str = name->as_utf8();
3765
3766 // Old prefixing may be defunct, strip prefixes, if any.
3767 for (int i = prefix_count-1; i >= 0; i--) {
3768 char* prefix = prefixes[i];
3769 size_t prefix_len = strlen(prefix);
3770 if (strncmp(prefix, name_str, prefix_len) == 0) {
3771 name_str += prefix_len;
3772 }
3773 }
3774 return name_str;
3775 }
3776
3777 // Strip any prefixes off the old native method, then try to find a
3778 // (possibly prefixed) new native that matches it.
3779 Method* strip_and_search_for_new_native(Method* method) {
3780 ResourceMark rm;
3781 char* name_str = method_name_without_prefixes(method);
3782 return search_prefix_name_space(0, name_str, strlen(name_str),
3783 method->signature());
3784 }
3785
3786 public:
3787
3788 // Construct a native method transfer processor for this class.
3789 TransferNativeFunctionRegistration(InstanceKlass* _the_class) {
3790 assert(SafepointSynchronize::is_at_safepoint(), "sanity check");
3791
3792 the_class = _the_class;
3793 prefixes = JvmtiExport::get_all_native_method_prefixes(&prefix_count);
3794 }
3795
3796 // Attempt to transfer any of the old or deleted methods that are native
3797 void transfer_registrations(Method** old_methods, int methods_length) {
3798 for (int j = 0; j < methods_length; j++) {
3799 Method* old_method = old_methods[j];
3800
3801 if (old_method->is_native() && old_method->has_native_function()) {
3802 Method* new_method = strip_and_search_for_new_native(old_method);
3803 if (new_method != NULL) {
3804 // Actually set the native function in the new method.
3805 // Redefine does not send events (except CFLH), certainly not this
3806 // behind the scenes re-registration.
3807 new_method->set_native_function(old_method->native_function(),
3808 !Method::native_bind_event_is_interesting);
3809 }
3810 }
3811 }
3812 }
3813 };
3814
3815 // Don't lose the association between a native method and its JNI function.
3816 void VM_RedefineClasses::transfer_old_native_function_registrations(InstanceKlass* the_class) {
3817 TransferNativeFunctionRegistration transfer(the_class);
3818 transfer.transfer_registrations(_deleted_methods, _deleted_methods_length);
3819 transfer.transfer_registrations(_matching_old_methods, _matching_methods_length);
3820 }
3821
3822 // Deoptimize all compiled code that depends on this class.
3823 //
3824 // If the can_redefine_classes capability is obtained in the onload
3825 // phase then the compiler has recorded all dependencies from startup.
3826 // In that case we need only deoptimize and throw away all compiled code
3827 // that depends on the class.
3828 //
3829 // If can_redefine_classes is obtained sometime after the onload
3830 // phase then the dependency information may be incomplete. In that case
3831 // the first call to RedefineClasses causes all compiled code to be
3832 // thrown away. As can_redefine_classes has been obtained then
3833 // all future compilations will record dependencies so second and
3834 // subsequent calls to RedefineClasses need only throw away code
3835 // that depends on the class.
3836 //
3837 void VM_RedefineClasses::flush_dependent_code(InstanceKlass* ik, TRAPS) {
3838 assert_locked_or_safepoint(Compile_lock);
3839
3840 // All dependencies have been recorded from startup or this is a second or
3841 // subsequent use of RedefineClasses
3842 if (JvmtiExport::all_dependencies_are_recorded()) {
3843 CodeCache::flush_evol_dependents_on(ik);
3844 } else {
3845 CodeCache::mark_all_nmethods_for_deoptimization();
3846
3847 ResourceMark rm(THREAD);
3848 DeoptimizationMarker dm;
3849
3850 // Deoptimize all activations depending on marked nmethods
3851 Deoptimization::deoptimize_dependents();
3852
3853 // Make the dependent methods not entrant
3854 CodeCache::make_marked_nmethods_not_entrant();
3855
3856 // From now on we know that the dependency information is complete
3857 JvmtiExport::set_all_dependencies_are_recorded(true);
3858 }
3859 }
3860
3861 void VM_RedefineClasses::compute_added_deleted_matching_methods() {
3862 Method* old_method;
3863 Method* new_method;
3864
3865 _matching_old_methods = NEW_RESOURCE_ARRAY(Method*, _old_methods->length());
3866 _matching_new_methods = NEW_RESOURCE_ARRAY(Method*, _old_methods->length());
3867 _added_methods = NEW_RESOURCE_ARRAY(Method*, _new_methods->length());
3868 _deleted_methods = NEW_RESOURCE_ARRAY(Method*, _old_methods->length());
3869
3870 _matching_methods_length = 0;
3871 _deleted_methods_length = 0;
3872 _added_methods_length = 0;
3873
3874 int nj = 0;
3875 int oj = 0;
3876 while (true) {
3877 if (oj >= _old_methods->length()) {
3878 if (nj >= _new_methods->length()) {
3879 break; // we've looked at everything, done
3880 }
3881 // New method at the end
3882 new_method = _new_methods->at(nj);
3883 _added_methods[_added_methods_length++] = new_method;
3884 ++nj;
3885 } else if (nj >= _new_methods->length()) {
3886 // Old method, at the end, is deleted
3887 old_method = _old_methods->at(oj);
3888 _deleted_methods[_deleted_methods_length++] = old_method;
3889 ++oj;
3890 } else {
3891 old_method = _old_methods->at(oj);
3892 new_method = _new_methods->at(nj);
3893 if (old_method->name() == new_method->name()) {
3894 if (old_method->signature() == new_method->signature()) {
3895 _matching_old_methods[_matching_methods_length ] = old_method;
3896 _matching_new_methods[_matching_methods_length++] = new_method;
3897 ++nj;
3898 ++oj;
3899 } else {
3900 // added overloaded have already been moved to the end,
3901 // so this is a deleted overloaded method
3902 _deleted_methods[_deleted_methods_length++] = old_method;
3903 ++oj;
3904 }
3905 } else { // names don't match
3906 if (old_method->name()->fast_compare(new_method->name()) > 0) {
3907 // new method
3908 _added_methods[_added_methods_length++] = new_method;
3909 ++nj;
3910 } else {
3911 // deleted method
3912 _deleted_methods[_deleted_methods_length++] = old_method;
3913 ++oj;
3914 }
3915 }
3916 }
3917 }
3918 assert(_matching_methods_length + _deleted_methods_length == _old_methods->length(), "sanity");
3919 assert(_matching_methods_length + _added_methods_length == _new_methods->length(), "sanity");
3920 }
3921
3922
3923 void VM_RedefineClasses::swap_annotations(InstanceKlass* the_class,
3924 InstanceKlass* scratch_class) {
3925 // Swap annotation fields values
3926 Annotations* old_annotations = the_class->annotations();
3927 the_class->set_annotations(scratch_class->annotations());
3928 scratch_class->set_annotations(old_annotations);
3929 }
3930
3931
3932 // Install the redefinition of a class:
3933 // - house keeping (flushing breakpoints and caches, deoptimizing
3934 // dependent compiled code)
3935 // - replacing parts in the_class with parts from scratch_class
3936 // - adding a weak reference to track the obsolete but interesting
3937 // parts of the_class
3938 // - adjusting constant pool caches and vtables in other classes
3939 // that refer to methods in the_class. These adjustments use the
3940 // ClassLoaderDataGraph::classes_do() facility which only allows
3941 // a helper method to be specified. The interesting parameters
3942 // that we would like to pass to the helper method are saved in
3943 // static global fields in the VM operation.
3944 void VM_RedefineClasses::redefine_single_class(jclass the_jclass,
3945 InstanceKlass* scratch_class, TRAPS) {
3946
3947 HandleMark hm(THREAD); // make sure handles from this call are freed
3948
3949 if (log_is_enabled(Info, redefine, class, timer)) {
3950 _timer_rsc_phase1.start();
3951 }
3952
3953 InstanceKlass* the_class = get_ik(the_jclass);
3954
3955 // Remove all breakpoints in methods of this class
3956 JvmtiBreakpoints& jvmti_breakpoints = JvmtiCurrentBreakpoints::get_jvmti_breakpoints();
3957 jvmti_breakpoints.clearall_in_class_at_safepoint(the_class);
3958
3959 // Deoptimize all compiled code that depends on this class
3960 flush_dependent_code(the_class, THREAD);
3961
3962 _old_methods = the_class->methods();
3963 _new_methods = scratch_class->methods();
3964 _the_class = the_class;
3965 compute_added_deleted_matching_methods();
3966 update_jmethod_ids();
3967
3968 _any_class_has_resolved_methods = the_class->has_resolved_methods() || _any_class_has_resolved_methods;
3969
3970 // Attach new constant pool to the original klass. The original
3971 // klass still refers to the old constant pool (for now).
3972 scratch_class->constants()->set_pool_holder(the_class);
3973
3974 #if 0
3975 // In theory, with constant pool merging in place we should be able
3976 // to save space by using the new, merged constant pool in place of
3977 // the old constant pool(s). By "pool(s)" I mean the constant pool in
3978 // the klass version we are replacing now and any constant pool(s) in
3979 // previous versions of klass. Nice theory, doesn't work in practice.
3980 // When this code is enabled, even simple programs throw NullPointer
3981 // exceptions. I'm guessing that this is caused by some constant pool
3982 // cache difference between the new, merged constant pool and the
3983 // constant pool that was just being used by the klass. I'm keeping
3984 // this code around to archive the idea, but the code has to remain
3985 // disabled for now.
3986
3987 // Attach each old method to the new constant pool. This can be
3988 // done here since we are past the bytecode verification and
3989 // constant pool optimization phases.
3990 for (int i = _old_methods->length() - 1; i >= 0; i--) {
3991 Method* method = _old_methods->at(i);
3992 method->set_constants(scratch_class->constants());
3993 }
3994
3995 // NOTE: this doesn't work because you can redefine the same class in two
3996 // threads, each getting their own constant pool data appended to the
3997 // original constant pool. In order for the new methods to work when they
3998 // become old methods, they need to keep their updated copy of the constant pool.
3999
4000 {
4001 // walk all previous versions of the klass
4002 InstanceKlass *ik = the_class;
4003 PreviousVersionWalker pvw(ik);
4004 do {
4005 ik = pvw.next_previous_version();
4006 if (ik != NULL) {
4007
4008 // attach previous version of klass to the new constant pool
4009 ik->set_constants(scratch_class->constants());
4010
4011 // Attach each method in the previous version of klass to the
4012 // new constant pool
4013 Array<Method*>* prev_methods = ik->methods();
4014 for (int i = prev_methods->length() - 1; i >= 0; i--) {
4015 Method* method = prev_methods->at(i);
4016 method->set_constants(scratch_class->constants());
4017 }
4018 }
4019 } while (ik != NULL);
4020 }
4021 #endif
4022
4023 // Replace methods and constantpool
4024 the_class->set_methods(_new_methods);
4025 scratch_class->set_methods(_old_methods); // To prevent potential GCing of the old methods,
4026 // and to be able to undo operation easily.
4027
4028 Array<int>* old_ordering = the_class->method_ordering();
4029 the_class->set_method_ordering(scratch_class->method_ordering());
4030 scratch_class->set_method_ordering(old_ordering);
4031
4032 ConstantPool* old_constants = the_class->constants();
4033 the_class->set_constants(scratch_class->constants());
4034 scratch_class->set_constants(old_constants); // See the previous comment.
4035 #if 0
4036 // We are swapping the guts of "the new class" with the guts of "the
4037 // class". Since the old constant pool has just been attached to "the
4038 // new class", it seems logical to set the pool holder in the old
4039 // constant pool also. However, doing this will change the observable
4040 // class hierarchy for any old methods that are still executing. A
4041 // method can query the identity of its "holder" and this query uses
4042 // the method's constant pool link to find the holder. The change in
4043 // holding class from "the class" to "the new class" can confuse
4044 // things.
4045 //
4046 // Setting the old constant pool's holder will also cause
4047 // verification done during vtable initialization below to fail.
4048 // During vtable initialization, the vtable's class is verified to be
4049 // a subtype of the method's holder. The vtable's class is "the
4050 // class" and the method's holder is gotten from the constant pool
4051 // link in the method itself. For "the class"'s directly implemented
4052 // methods, the method holder is "the class" itself (as gotten from
4053 // the new constant pool). The check works fine in this case. The
4054 // check also works fine for methods inherited from super classes.
4055 //
4056 // Miranda methods are a little more complicated. A miranda method is
4057 // provided by an interface when the class implementing the interface
4058 // does not provide its own method. These interfaces are implemented
4059 // internally as an InstanceKlass. These special instanceKlasses
4060 // share the constant pool of the class that "implements" the
4061 // interface. By sharing the constant pool, the method holder of a
4062 // miranda method is the class that "implements" the interface. In a
4063 // non-redefine situation, the subtype check works fine. However, if
4064 // the old constant pool's pool holder is modified, then the check
4065 // fails because there is no class hierarchy relationship between the
4066 // vtable's class and "the new class".
4067
4068 old_constants->set_pool_holder(scratch_class());
4069 #endif
4070
4071 // track number of methods that are EMCP for add_previous_version() call below
4072 int emcp_method_count = check_methods_and_mark_as_obsolete();
4073 transfer_old_native_function_registrations(the_class);
4074
4075 // The class file bytes from before any retransformable agents mucked
4076 // with them was cached on the scratch class, move to the_class.
4077 // Note: we still want to do this if nothing needed caching since it
4078 // should get cleared in the_class too.
4079 if (the_class->get_cached_class_file() == 0) {
4080 // the_class doesn't have a cache yet so copy it
4081 the_class->set_cached_class_file(scratch_class->get_cached_class_file());
4082 }
4083 else if (scratch_class->get_cached_class_file() !=
4084 the_class->get_cached_class_file()) {
4085 // The same class can be present twice in the scratch classes list or there
4086 // are multiple concurrent RetransformClasses calls on different threads.
4087 // In such cases we have to deallocate scratch_class cached_class_file.
4088 os::free(scratch_class->get_cached_class_file());
4089 }
4090
4091 // NULL out in scratch class to not delete twice. The class to be redefined
4092 // always owns these bytes.
4093 scratch_class->set_cached_class_file(NULL);
4094
4095 // Replace inner_classes
4096 Array<u2>* old_inner_classes = the_class->inner_classes();
4097 the_class->set_inner_classes(scratch_class->inner_classes());
4098 scratch_class->set_inner_classes(old_inner_classes);
4099
4100 // Initialize the vtable and interface table after
4101 // methods have been rewritten
4102 // no exception should happen here since we explicitly
4103 // do not check loader constraints.
4104 // compare_and_normalize_class_versions has already checked:
4105 // - classloaders unchanged, signatures unchanged
4106 // - all instanceKlasses for redefined classes reused & contents updated
4107 the_class->vtable().initialize_vtable(false, THREAD);
4108 the_class->itable().initialize_itable(false, THREAD);
4109 assert(!HAS_PENDING_EXCEPTION || (THREAD->pending_exception()->is_a(SystemDictionary::ThreadDeath_klass())), "redefine exception");
4110
4111 // Leave arrays of jmethodIDs and itable index cache unchanged
4112
4113 // Copy the "source file name" attribute from new class version
4114 the_class->set_source_file_name_index(
4115 scratch_class->source_file_name_index());
4116
4117 // Copy the "source debug extension" attribute from new class version
4118 the_class->set_source_debug_extension(
4119 scratch_class->source_debug_extension(),
4120 scratch_class->source_debug_extension() == NULL ? 0 :
4121 (int)strlen(scratch_class->source_debug_extension()));
4122
4123 // Use of javac -g could be different in the old and the new
4124 if (scratch_class->access_flags().has_localvariable_table() !=
4125 the_class->access_flags().has_localvariable_table()) {
4126
4127 AccessFlags flags = the_class->access_flags();
4128 if (scratch_class->access_flags().has_localvariable_table()) {
4129 flags.set_has_localvariable_table();
4130 } else {
4131 flags.clear_has_localvariable_table();
4132 }
4133 the_class->set_access_flags(flags);
4134 }
4135
4136 swap_annotations(the_class, scratch_class);
4137
4138 // Replace minor version number of class file
4139 u2 old_minor_version = the_class->minor_version();
4140 the_class->set_minor_version(scratch_class->minor_version());
4141 scratch_class->set_minor_version(old_minor_version);
4142
4143 // Replace major version number of class file
4144 u2 old_major_version = the_class->major_version();
4145 the_class->set_major_version(scratch_class->major_version());
4146 scratch_class->set_major_version(old_major_version);
4147
4148 // Replace CP indexes for class and name+type of enclosing method
4149 u2 old_class_idx = the_class->enclosing_method_class_index();
4150 u2 old_method_idx = the_class->enclosing_method_method_index();
4151 the_class->set_enclosing_method_indices(
4152 scratch_class->enclosing_method_class_index(),
4153 scratch_class->enclosing_method_method_index());
4154 scratch_class->set_enclosing_method_indices(old_class_idx, old_method_idx);
4155
4156 // Replace fingerprint data
4157 the_class->set_has_passed_fingerprint_check(scratch_class->has_passed_fingerprint_check());
4158 the_class->store_fingerprint(scratch_class->get_stored_fingerprint());
4159
4160 the_class->set_has_been_redefined();
4161
4162 if (!the_class->should_be_initialized()) {
4163 // Class was already initialized, so AOT has only seen the original version.
4164 // We need to let AOT look at it again.
4165 AOTLoader::load_for_klass(the_class, THREAD);
4166 }
4167
4168 // keep track of previous versions of this class
4169 the_class->add_previous_version(scratch_class, emcp_method_count);
4170
4171 _timer_rsc_phase1.stop();
4172 if (log_is_enabled(Info, redefine, class, timer)) {
4173 _timer_rsc_phase2.start();
4174 }
4175
4176 // Adjust constantpool caches and vtables for all classes
4177 // that reference methods of the evolved class.
4178 AdjustCpoolCacheAndVtable adjust_cpool_cache_and_vtable(THREAD);
4179 ClassLoaderDataGraph::classes_do(&adjust_cpool_cache_and_vtable);
4180
4181 if (the_class->oop_map_cache() != NULL) {
4182 // Flush references to any obsolete methods from the oop map cache
4183 // so that obsolete methods are not pinned.
4184 the_class->oop_map_cache()->flush_obsolete_entries();
4185 }
4186
4187 increment_class_counter((InstanceKlass *)the_class, THREAD);
4188 {
4189 ResourceMark rm(THREAD);
4190 // increment the classRedefinedCount field in the_class and in any
4191 // direct and indirect subclasses of the_class
4192 log_info(redefine, class, load)
4193 ("redefined name=%s, count=%d (avail_mem=" UINT64_FORMAT "K)",
4194 the_class->external_name(), java_lang_Class::classRedefinedCount(the_class->java_mirror()), os::available_memory() >> 10);
4195 Events::log_redefinition(THREAD, "redefined class name=%s, count=%d",
4196 the_class->external_name(),
4197 java_lang_Class::classRedefinedCount(the_class->java_mirror()));
4198
4199 }
4200 _timer_rsc_phase2.stop();
4201 } // end redefine_single_class()
4202
4203
4204 // Increment the classRedefinedCount field in the specific InstanceKlass
4205 // and in all direct and indirect subclasses.
4206 void VM_RedefineClasses::increment_class_counter(InstanceKlass *ik, TRAPS) {
4207 oop class_mirror = ik->java_mirror();
4208 Klass* class_oop = java_lang_Class::as_Klass(class_mirror);
4209 int new_count = java_lang_Class::classRedefinedCount(class_mirror) + 1;
4210 java_lang_Class::set_classRedefinedCount(class_mirror, new_count);
4211
4212 if (class_oop != _the_class) {
4213 // _the_class count is printed at end of redefine_single_class()
4214 log_debug(redefine, class, subclass)("updated count in subclass=%s to %d", ik->external_name(), new_count);
4215 }
4216
4217 for (Klass *subk = ik->subklass(); subk != NULL;
4218 subk = subk->next_sibling()) {
4219 if (subk->is_instance_klass()) {
4220 // Only update instanceKlasses
4221 InstanceKlass *subik = InstanceKlass::cast(subk);
4222 // recursively do subclasses of the current subclass
4223 increment_class_counter(subik, THREAD);
4224 }
4225 }
4226 }
4227
4228 void VM_RedefineClasses::CheckClass::do_klass(Klass* k) {
4229 bool no_old_methods = true; // be optimistic
4230
4231 // Both array and instance classes have vtables.
4232 // a vtable should never contain old or obsolete methods
4233 ResourceMark rm(_thread);
4234 if (k->vtable_length() > 0 &&
4235 !k->vtable().check_no_old_or_obsolete_entries()) {
4236 if (log_is_enabled(Trace, redefine, class, obsolete, metadata)) {
4237 log_trace(redefine, class, obsolete, metadata)
4238 ("klassVtable::check_no_old_or_obsolete_entries failure -- OLD or OBSOLETE method found -- class: %s",
4239 k->signature_name());
4240 k->vtable().dump_vtable();
4241 }
4242 no_old_methods = false;
4243 }
4244
4245 if (k->is_instance_klass()) {
4246 HandleMark hm(_thread);
4247 InstanceKlass *ik = InstanceKlass::cast(k);
4248
4249 // an itable should never contain old or obsolete methods
4250 if (ik->itable_length() > 0 &&
4251 !ik->itable().check_no_old_or_obsolete_entries()) {
4252 if (log_is_enabled(Trace, redefine, class, obsolete, metadata)) {
4253 log_trace(redefine, class, obsolete, metadata)
4254 ("klassItable::check_no_old_or_obsolete_entries failure -- OLD or OBSOLETE method found -- class: %s",
4255 ik->signature_name());
4256 ik->itable().dump_itable();
4257 }
4258 no_old_methods = false;
4259 }
4260
4261 // the constant pool cache should never contain non-deleted old or obsolete methods
4262 if (ik->constants() != NULL &&
4263 ik->constants()->cache() != NULL &&
4264 !ik->constants()->cache()->check_no_old_or_obsolete_entries()) {
4265 if (log_is_enabled(Trace, redefine, class, obsolete, metadata)) {
4266 log_trace(redefine, class, obsolete, metadata)
4267 ("cp-cache::check_no_old_or_obsolete_entries failure -- OLD or OBSOLETE method found -- class: %s",
4268 ik->signature_name());
4269 ik->constants()->cache()->dump_cache();
4270 }
4271 no_old_methods = false;
4272 }
4273 }
4274
4275 // print and fail guarantee if old methods are found.
4276 if (!no_old_methods) {
4277 if (log_is_enabled(Trace, redefine, class, obsolete, metadata)) {
4278 dump_methods();
4279 } else {
4280 log_trace(redefine, class)("Use the '-Xlog:redefine+class*:' option "
4281 "to see more info about the following guarantee() failure.");
4282 }
4283 guarantee(false, "OLD and/or OBSOLETE method(s) found");
4284 }
4285 }
4286
4287
4288 void VM_RedefineClasses::dump_methods() {
4289 int j;
4290 log_trace(redefine, class, dump)("_old_methods --");
4291 for (j = 0; j < _old_methods->length(); ++j) {
4292 LogStreamHandle(Trace, redefine, class, dump) log_stream;
4293 Method* m = _old_methods->at(j);
4294 log_stream.print("%4d (%5d) ", j, m->vtable_index());
4295 m->access_flags().print_on(&log_stream);
4296 log_stream.print(" -- ");
4297 m->print_name(&log_stream);
4298 log_stream.cr();
4299 }
4300 log_trace(redefine, class, dump)("_new_methods --");
4301 for (j = 0; j < _new_methods->length(); ++j) {
4302 LogStreamHandle(Trace, redefine, class, dump) log_stream;
4303 Method* m = _new_methods->at(j);
4304 log_stream.print("%4d (%5d) ", j, m->vtable_index());
4305 m->access_flags().print_on(&log_stream);
4306 log_stream.print(" -- ");
4307 m->print_name(&log_stream);
4308 log_stream.cr();
4309 }
4310 log_trace(redefine, class, dump)("_matching_methods --");
4311 for (j = 0; j < _matching_methods_length; ++j) {
4312 LogStreamHandle(Trace, redefine, class, dump) log_stream;
4313 Method* m = _matching_old_methods[j];
4314 log_stream.print("%4d (%5d) ", j, m->vtable_index());
4315 m->access_flags().print_on(&log_stream);
4316 log_stream.print(" -- ");
4317 m->print_name();
4318 log_stream.cr();
4319
4320 m = _matching_new_methods[j];
4321 log_stream.print(" (%5d) ", m->vtable_index());
4322 m->access_flags().print_on(&log_stream);
4323 log_stream.cr();
4324 }
4325 log_trace(redefine, class, dump)("_deleted_methods --");
4326 for (j = 0; j < _deleted_methods_length; ++j) {
4327 LogStreamHandle(Trace, redefine, class, dump) log_stream;
4328 Method* m = _deleted_methods[j];
4329 log_stream.print("%4d (%5d) ", j, m->vtable_index());
4330 m->access_flags().print_on(&log_stream);
4331 log_stream.print(" -- ");
4332 m->print_name(&log_stream);
4333 log_stream.cr();
4334 }
4335 log_trace(redefine, class, dump)("_added_methods --");
4336 for (j = 0; j < _added_methods_length; ++j) {
4337 LogStreamHandle(Trace, redefine, class, dump) log_stream;
4338 Method* m = _added_methods[j];
4339 log_stream.print("%4d (%5d) ", j, m->vtable_index());
4340 m->access_flags().print_on(&log_stream);
4341 log_stream.print(" -- ");
4342 m->print_name(&log_stream);
4343 log_stream.cr();
4344 }
4345 }
4346
4347 void VM_RedefineClasses::print_on_error(outputStream* st) const {
4348 VM_Operation::print_on_error(st);
4349 if (_the_class != NULL) {
4350 ResourceMark rm;
4351 st->print_cr(", redefining class %s", _the_class->external_name());
4352 }
4353 }