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(
1235 scratch_class, Verifier::ThrowException, true, THREAD);
1236 }
1237
1238 if (HAS_PENDING_EXCEPTION) {
1239 Symbol* ex_name = PENDING_EXCEPTION->klass()->name();
1240 log_info(redefine, class, load, exceptions)("verify_byte_codes exception: '%s'", ex_name->as_C_string());
1241 CLEAR_PENDING_EXCEPTION;
1242 if (ex_name == vmSymbols::java_lang_OutOfMemoryError()) {
1243 return JVMTI_ERROR_OUT_OF_MEMORY;
1244 } else {
1245 // tell the caller the bytecodes are bad
1246 return JVMTI_ERROR_FAILS_VERIFICATION;
1247 }
1248 }
1249
1250 res = merge_cp_and_rewrite(the_class, scratch_class, THREAD);
1251 if (HAS_PENDING_EXCEPTION) {
1252 Symbol* ex_name = PENDING_EXCEPTION->klass()->name();
1253 log_info(redefine, class, load, exceptions)("merge_cp_and_rewrite exception: '%s'", ex_name->as_C_string());
1254 CLEAR_PENDING_EXCEPTION;
1255 if (ex_name == vmSymbols::java_lang_OutOfMemoryError()) {
1256 return JVMTI_ERROR_OUT_OF_MEMORY;
1257 } else {
1258 return JVMTI_ERROR_INTERNAL;
1259 }
1260 }
1261
1262 if (VerifyMergedCPBytecodes) {
1263 // verify what we have done during constant pool merging
1264 {
1265 RedefineVerifyMark rvm(the_class, scratch_class, state);
1266 Verifier::verify(scratch_class, Verifier::ThrowException, true, THREAD);
1267 }
1268
1269 if (HAS_PENDING_EXCEPTION) {
1270 Symbol* ex_name = PENDING_EXCEPTION->klass()->name();
1271 log_info(redefine, class, load, exceptions)
1272 ("verify_byte_codes post merge-CP exception: '%s'", ex_name->as_C_string());
1273 CLEAR_PENDING_EXCEPTION;
1274 if (ex_name == vmSymbols::java_lang_OutOfMemoryError()) {
1275 return JVMTI_ERROR_OUT_OF_MEMORY;
1276 } else {
1277 // tell the caller that constant pool merging screwed up
1278 return JVMTI_ERROR_INTERNAL;
1279 }
1280 }
1281 }
1282
1283 Rewriter::rewrite(scratch_class, THREAD);
1284 if (!HAS_PENDING_EXCEPTION) {
1285 scratch_class->link_methods(THREAD);
1286 }
1287 if (HAS_PENDING_EXCEPTION) {
1288 Symbol* ex_name = PENDING_EXCEPTION->klass()->name();
1289 log_info(redefine, class, load, exceptions)
1290 ("Rewriter::rewrite or link_methods exception: '%s'", ex_name->as_C_string());
1291 CLEAR_PENDING_EXCEPTION;
1292 if (ex_name == vmSymbols::java_lang_OutOfMemoryError()) {
1293 return JVMTI_ERROR_OUT_OF_MEMORY;
1294 } else {
1295 return JVMTI_ERROR_INTERNAL;
1296 }
1297 }
1298
1299 log_debug(redefine, class, load)
1300 ("loaded name=%s (avail_mem=" UINT64_FORMAT "K)", the_class->external_name(), os::available_memory() >> 10);
1301 }
1302
1303 return JVMTI_ERROR_NONE;
1304 }
1305
1306
1307 // Map old_index to new_index as needed. scratch_cp is only needed
1308 // for log calls.
1309 void VM_RedefineClasses::map_index(const constantPoolHandle& scratch_cp,
1310 int old_index, int new_index) {
1311 if (find_new_index(old_index) != 0) {
1312 // old_index is already mapped
1313 return;
1314 }
1315
1316 if (old_index == new_index) {
1317 // no mapping is needed
1318 return;
1319 }
1320
1321 _index_map_p->at_put(old_index, new_index);
1322 _index_map_count++;
1323
1324 log_trace(redefine, class, constantpool)
1325 ("mapped tag %d at index %d to %d", scratch_cp->tag_at(old_index).value(), old_index, new_index);
1326 } // end map_index()
1327
1328
1329 // Map old_index to new_index as needed.
1330 void VM_RedefineClasses::map_operand_index(int old_index, int new_index) {
1331 if (find_new_operand_index(old_index) != -1) {
1332 // old_index is already mapped
1333 return;
1334 }
1335
1336 if (old_index == new_index) {
1337 // no mapping is needed
1338 return;
1339 }
1340
1341 _operands_index_map_p->at_put(old_index, new_index);
1342 _operands_index_map_count++;
1343
1344 log_trace(redefine, class, constantpool)("mapped bootstrap specifier at index %d to %d", old_index, new_index);
1345 } // end map_index()
1346
1347
1348 // Merge old_cp and scratch_cp and return the results of the merge via
1349 // merge_cp_p. The number of entries in *merge_cp_p is returned via
1350 // merge_cp_length_p. The entries in old_cp occupy the same locations
1351 // in *merge_cp_p. Also creates a map of indices from entries in
1352 // scratch_cp to the corresponding entry in *merge_cp_p. Index map
1353 // entries are only created for entries in scratch_cp that occupy a
1354 // different location in *merged_cp_p.
1355 bool VM_RedefineClasses::merge_constant_pools(const constantPoolHandle& old_cp,
1356 const constantPoolHandle& scratch_cp, constantPoolHandle *merge_cp_p,
1357 int *merge_cp_length_p, TRAPS) {
1358
1359 if (merge_cp_p == NULL) {
1360 assert(false, "caller must provide scratch constantPool");
1361 return false; // robustness
1362 }
1363 if (merge_cp_length_p == NULL) {
1364 assert(false, "caller must provide scratch CP length");
1365 return false; // robustness
1366 }
1367 // Worst case we need old_cp->length() + scratch_cp()->length(),
1368 // but the caller might be smart so make sure we have at least
1369 // the minimum.
1370 if ((*merge_cp_p)->length() < old_cp->length()) {
1371 assert(false, "merge area too small");
1372 return false; // robustness
1373 }
1374
1375 log_info(redefine, class, constantpool)("old_cp_len=%d, scratch_cp_len=%d", old_cp->length(), scratch_cp->length());
1376
1377 {
1378 // Pass 0:
1379 // The old_cp is copied to *merge_cp_p; this means that any code
1380 // using old_cp does not have to change. This work looks like a
1381 // perfect fit for ConstantPool*::copy_cp_to(), but we need to
1382 // handle one special case:
1383 // - revert JVM_CONSTANT_Class to JVM_CONSTANT_UnresolvedClass
1384 // This will make verification happy.
1385
1386 int old_i; // index into old_cp
1387
1388 // index zero (0) is not used in constantPools
1389 for (old_i = 1; old_i < old_cp->length(); old_i++) {
1390 // leave debugging crumb
1391 jbyte old_tag = old_cp->tag_at(old_i).value();
1392 switch (old_tag) {
1393 case JVM_CONSTANT_Class:
1394 case JVM_CONSTANT_UnresolvedClass:
1395 // revert the copy to JVM_CONSTANT_UnresolvedClass
1396 // May be resolving while calling this so do the same for
1397 // JVM_CONSTANT_UnresolvedClass (klass_name_at() deals with transition)
1398 (*merge_cp_p)->temp_unresolved_klass_at_put(old_i,
1399 old_cp->klass_name_index_at(old_i));
1400 break;
1401
1402 case JVM_CONSTANT_Double:
1403 case JVM_CONSTANT_Long:
1404 // just copy the entry to *merge_cp_p, but double and long take
1405 // two constant pool entries
1406 ConstantPool::copy_entry_to(old_cp, old_i, *merge_cp_p, old_i, CHECK_0);
1407 old_i++;
1408 break;
1409
1410 default:
1411 // just copy the entry to *merge_cp_p
1412 ConstantPool::copy_entry_to(old_cp, old_i, *merge_cp_p, old_i, CHECK_0);
1413 break;
1414 }
1415 } // end for each old_cp entry
1416
1417 ConstantPool::copy_operands(old_cp, *merge_cp_p, CHECK_0);
1418 (*merge_cp_p)->extend_operands(scratch_cp, CHECK_0);
1419
1420 // We don't need to sanity check that *merge_cp_length_p is within
1421 // *merge_cp_p bounds since we have the minimum on-entry check above.
1422 (*merge_cp_length_p) = old_i;
1423 }
1424
1425 // merge_cp_len should be the same as old_cp->length() at this point
1426 // so this trace message is really a "warm-and-breathing" message.
1427 log_debug(redefine, class, constantpool)("after pass 0: merge_cp_len=%d", *merge_cp_length_p);
1428
1429 int scratch_i; // index into scratch_cp
1430 {
1431 // Pass 1a:
1432 // Compare scratch_cp entries to the old_cp entries that we have
1433 // already copied to *merge_cp_p. In this pass, we are eliminating
1434 // exact duplicates (matching entry at same index) so we only
1435 // compare entries in the common indice range.
1436 int increment = 1;
1437 int pass1a_length = MIN2(old_cp->length(), scratch_cp->length());
1438 for (scratch_i = 1; scratch_i < pass1a_length; scratch_i += increment) {
1439 switch (scratch_cp->tag_at(scratch_i).value()) {
1440 case JVM_CONSTANT_Double:
1441 case JVM_CONSTANT_Long:
1442 // double and long take two constant pool entries
1443 increment = 2;
1444 break;
1445
1446 default:
1447 increment = 1;
1448 break;
1449 }
1450
1451 bool match = scratch_cp->compare_entry_to(scratch_i, *merge_cp_p,
1452 scratch_i, CHECK_0);
1453 if (match) {
1454 // found a match at the same index so nothing more to do
1455 continue;
1456 } else if (is_unresolved_class_mismatch(scratch_cp, scratch_i,
1457 *merge_cp_p, scratch_i)) {
1458 // The mismatch in compare_entry_to() above is because of a
1459 // resolved versus unresolved class entry at the same index
1460 // with the same string value. Since Pass 0 reverted any
1461 // class entries to unresolved class entries in *merge_cp_p,
1462 // we go with the unresolved class entry.
1463 continue;
1464 }
1465
1466 int found_i = scratch_cp->find_matching_entry(scratch_i, *merge_cp_p,
1467 CHECK_0);
1468 if (found_i != 0) {
1469 guarantee(found_i != scratch_i,
1470 "compare_entry_to() and find_matching_entry() do not agree");
1471
1472 // Found a matching entry somewhere else in *merge_cp_p so
1473 // just need a mapping entry.
1474 map_index(scratch_cp, scratch_i, found_i);
1475 continue;
1476 }
1477
1478 // The find_matching_entry() call above could fail to find a match
1479 // due to a resolved versus unresolved class or string entry situation
1480 // like we solved above with the is_unresolved_*_mismatch() calls.
1481 // However, we would have to call is_unresolved_*_mismatch() over
1482 // all of *merge_cp_p (potentially) and that doesn't seem to be
1483 // worth the time.
1484
1485 // No match found so we have to append this entry and any unique
1486 // referenced entries to *merge_cp_p.
1487 append_entry(scratch_cp, scratch_i, merge_cp_p, merge_cp_length_p,
1488 CHECK_0);
1489 }
1490 }
1491
1492 log_debug(redefine, class, constantpool)
1493 ("after pass 1a: merge_cp_len=%d, scratch_i=%d, index_map_len=%d",
1494 *merge_cp_length_p, scratch_i, _index_map_count);
1495
1496 if (scratch_i < scratch_cp->length()) {
1497 // Pass 1b:
1498 // old_cp is smaller than scratch_cp so there are entries in
1499 // scratch_cp that we have not yet processed. We take care of
1500 // those now.
1501 int increment = 1;
1502 for (; scratch_i < scratch_cp->length(); scratch_i += increment) {
1503 switch (scratch_cp->tag_at(scratch_i).value()) {
1504 case JVM_CONSTANT_Double:
1505 case JVM_CONSTANT_Long:
1506 // double and long take two constant pool entries
1507 increment = 2;
1508 break;
1509
1510 default:
1511 increment = 1;
1512 break;
1513 }
1514
1515 int found_i =
1516 scratch_cp->find_matching_entry(scratch_i, *merge_cp_p, CHECK_0);
1517 if (found_i != 0) {
1518 // Found a matching entry somewhere else in *merge_cp_p so
1519 // just need a mapping entry.
1520 map_index(scratch_cp, scratch_i, found_i);
1521 continue;
1522 }
1523
1524 // No match found so we have to append this entry and any unique
1525 // referenced entries to *merge_cp_p.
1526 append_entry(scratch_cp, scratch_i, merge_cp_p, merge_cp_length_p,
1527 CHECK_0);
1528 }
1529
1530 log_debug(redefine, class, constantpool)
1531 ("after pass 1b: merge_cp_len=%d, scratch_i=%d, index_map_len=%d",
1532 *merge_cp_length_p, scratch_i, _index_map_count);
1533 }
1534 finalize_operands_merge(*merge_cp_p, THREAD);
1535
1536 return true;
1537 } // end merge_constant_pools()
1538
1539
1540 // Scoped object to clean up the constant pool(s) created for merging
1541 class MergeCPCleaner {
1542 ClassLoaderData* _loader_data;
1543 ConstantPool* _cp;
1544 ConstantPool* _scratch_cp;
1545 public:
1546 MergeCPCleaner(ClassLoaderData* loader_data, ConstantPool* merge_cp) :
1547 _loader_data(loader_data), _cp(merge_cp), _scratch_cp(NULL) {}
1548 ~MergeCPCleaner() {
1549 _loader_data->add_to_deallocate_list(_cp);
1550 if (_scratch_cp != NULL) {
1551 _loader_data->add_to_deallocate_list(_scratch_cp);
1552 }
1553 }
1554 void add_scratch_cp(ConstantPool* scratch_cp) { _scratch_cp = scratch_cp; }
1555 };
1556
1557 // Merge constant pools between the_class and scratch_class and
1558 // potentially rewrite bytecodes in scratch_class to use the merged
1559 // constant pool.
1560 jvmtiError VM_RedefineClasses::merge_cp_and_rewrite(
1561 InstanceKlass* the_class, InstanceKlass* scratch_class,
1562 TRAPS) {
1563 // worst case merged constant pool length is old and new combined
1564 int merge_cp_length = the_class->constants()->length()
1565 + scratch_class->constants()->length();
1566
1567 // Constant pools are not easily reused so we allocate a new one
1568 // each time.
1569 // merge_cp is created unsafe for concurrent GC processing. It
1570 // should be marked safe before discarding it. Even though
1571 // garbage, if it crosses a card boundary, it may be scanned
1572 // in order to find the start of the first complete object on the card.
1573 ClassLoaderData* loader_data = the_class->class_loader_data();
1574 ConstantPool* merge_cp_oop =
1575 ConstantPool::allocate(loader_data,
1576 merge_cp_length,
1577 CHECK_(JVMTI_ERROR_OUT_OF_MEMORY));
1578 MergeCPCleaner cp_cleaner(loader_data, merge_cp_oop);
1579
1580 HandleMark hm(THREAD); // make sure handles are cleared before
1581 // MergeCPCleaner clears out merge_cp_oop
1582 constantPoolHandle merge_cp(THREAD, merge_cp_oop);
1583
1584 // Get constants() from the old class because it could have been rewritten
1585 // while we were at a safepoint allocating a new constant pool.
1586 constantPoolHandle old_cp(THREAD, the_class->constants());
1587 constantPoolHandle scratch_cp(THREAD, scratch_class->constants());
1588
1589 // If the length changed, the class was redefined out from under us. Return
1590 // an error.
1591 if (merge_cp_length != the_class->constants()->length()
1592 + scratch_class->constants()->length()) {
1593 return JVMTI_ERROR_INTERNAL;
1594 }
1595
1596 // Update the version number of the constant pools (may keep scratch_cp)
1597 merge_cp->increment_and_save_version(old_cp->version());
1598 scratch_cp->increment_and_save_version(old_cp->version());
1599
1600 ResourceMark rm(THREAD);
1601 _index_map_count = 0;
1602 _index_map_p = new intArray(scratch_cp->length(), scratch_cp->length(), -1);
1603
1604 _operands_cur_length = ConstantPool::operand_array_length(old_cp->operands());
1605 _operands_index_map_count = 0;
1606 int operands_index_map_len = ConstantPool::operand_array_length(scratch_cp->operands());
1607 _operands_index_map_p = new intArray(operands_index_map_len, operands_index_map_len, -1);
1608
1609 // reference to the cp holder is needed for copy_operands()
1610 merge_cp->set_pool_holder(scratch_class);
1611 bool result = merge_constant_pools(old_cp, scratch_cp, &merge_cp,
1612 &merge_cp_length, THREAD);
1613 merge_cp->set_pool_holder(NULL);
1614
1615 if (!result) {
1616 // The merge can fail due to memory allocation failure or due
1617 // to robustness checks.
1618 return JVMTI_ERROR_INTERNAL;
1619 }
1620
1621 log_info(redefine, class, constantpool)("merge_cp_len=%d, index_map_len=%d", merge_cp_length, _index_map_count);
1622
1623 if (_index_map_count == 0) {
1624 // there is nothing to map between the new and merged constant pools
1625
1626 if (old_cp->length() == scratch_cp->length()) {
1627 // The old and new constant pools are the same length and the
1628 // index map is empty. This means that the three constant pools
1629 // are equivalent (but not the same). Unfortunately, the new
1630 // constant pool has not gone through link resolution nor have
1631 // the new class bytecodes gone through constant pool cache
1632 // rewriting so we can't use the old constant pool with the new
1633 // class.
1634
1635 // toss the merged constant pool at return
1636 } else if (old_cp->length() < scratch_cp->length()) {
1637 // The old constant pool has fewer entries than the new constant
1638 // pool and the index map is empty. This means the new constant
1639 // pool is a superset of the old constant pool. However, the old
1640 // class bytecodes have already gone through constant pool cache
1641 // rewriting so we can't use the new constant pool with the old
1642 // class.
1643
1644 // toss the merged constant pool at return
1645 } else {
1646 // The old constant pool has more entries than the new constant
1647 // pool and the index map is empty. This means that both the old
1648 // and merged constant pools are supersets of the new constant
1649 // pool.
1650
1651 // Replace the new constant pool with a shrunken copy of the
1652 // merged constant pool
1653 set_new_constant_pool(loader_data, scratch_class, merge_cp, merge_cp_length,
1654 CHECK_(JVMTI_ERROR_OUT_OF_MEMORY));
1655 // The new constant pool replaces scratch_cp so have cleaner clean it up.
1656 // It can't be cleaned up while there are handles to it.
1657 cp_cleaner.add_scratch_cp(scratch_cp());
1658 }
1659 } else {
1660 if (log_is_enabled(Trace, redefine, class, constantpool)) {
1661 // don't want to loop unless we are tracing
1662 int count = 0;
1663 for (int i = 1; i < _index_map_p->length(); i++) {
1664 int value = _index_map_p->at(i);
1665
1666 if (value != -1) {
1667 log_trace(redefine, class, constantpool)("index_map[%d]: old=%d new=%d", count, i, value);
1668 count++;
1669 }
1670 }
1671 }
1672
1673 // We have entries mapped between the new and merged constant pools
1674 // so we have to rewrite some constant pool references.
1675 if (!rewrite_cp_refs(scratch_class, THREAD)) {
1676 return JVMTI_ERROR_INTERNAL;
1677 }
1678
1679 // Replace the new constant pool with a shrunken copy of the
1680 // merged constant pool so now the rewritten bytecodes have
1681 // valid references; the previous new constant pool will get
1682 // GCed.
1683 set_new_constant_pool(loader_data, scratch_class, merge_cp, merge_cp_length,
1684 CHECK_(JVMTI_ERROR_OUT_OF_MEMORY));
1685 // The new constant pool replaces scratch_cp so have cleaner clean it up.
1686 // It can't be cleaned up while there are handles to it.
1687 cp_cleaner.add_scratch_cp(scratch_cp());
1688 }
1689
1690 return JVMTI_ERROR_NONE;
1691 } // end merge_cp_and_rewrite()
1692
1693
1694 // Rewrite constant pool references in klass scratch_class.
1695 bool VM_RedefineClasses::rewrite_cp_refs(InstanceKlass* scratch_class,
1696 TRAPS) {
1697
1698 // rewrite constant pool references in the nest attributes:
1699 if (!rewrite_cp_refs_in_nest_attributes(scratch_class)) {
1700 // propagate failure back to caller
1701 return false;
1702 }
1703
1704 // rewrite constant pool references in the methods:
1705 if (!rewrite_cp_refs_in_methods(scratch_class, THREAD)) {
1706 // propagate failure back to caller
1707 return false;
1708 }
1709
1710 // rewrite constant pool references in the class_annotations:
1711 if (!rewrite_cp_refs_in_class_annotations(scratch_class, THREAD)) {
1712 // propagate failure back to caller
1713 return false;
1714 }
1715
1716 // rewrite constant pool references in the fields_annotations:
1717 if (!rewrite_cp_refs_in_fields_annotations(scratch_class, THREAD)) {
1718 // propagate failure back to caller
1719 return false;
1720 }
1721
1722 // rewrite constant pool references in the methods_annotations:
1723 if (!rewrite_cp_refs_in_methods_annotations(scratch_class, THREAD)) {
1724 // propagate failure back to caller
1725 return false;
1726 }
1727
1728 // rewrite constant pool references in the methods_parameter_annotations:
1729 if (!rewrite_cp_refs_in_methods_parameter_annotations(scratch_class,
1730 THREAD)) {
1731 // propagate failure back to caller
1732 return false;
1733 }
1734
1735 // rewrite constant pool references in the methods_default_annotations:
1736 if (!rewrite_cp_refs_in_methods_default_annotations(scratch_class,
1737 THREAD)) {
1738 // propagate failure back to caller
1739 return false;
1740 }
1741
1742 // rewrite constant pool references in the class_type_annotations:
1743 if (!rewrite_cp_refs_in_class_type_annotations(scratch_class, THREAD)) {
1744 // propagate failure back to caller
1745 return false;
1746 }
1747
1748 // rewrite constant pool references in the fields_type_annotations:
1749 if (!rewrite_cp_refs_in_fields_type_annotations(scratch_class, THREAD)) {
1750 // propagate failure back to caller
1751 return false;
1752 }
1753
1754 // rewrite constant pool references in the methods_type_annotations:
1755 if (!rewrite_cp_refs_in_methods_type_annotations(scratch_class, THREAD)) {
1756 // propagate failure back to caller
1757 return false;
1758 }
1759
1760 // There can be type annotations in the Code part of a method_info attribute.
1761 // These annotations are not accessible, even by reflection.
1762 // Currently they are not even parsed by the ClassFileParser.
1763 // If runtime access is added they will also need to be rewritten.
1764
1765 // rewrite source file name index:
1766 u2 source_file_name_idx = scratch_class->source_file_name_index();
1767 if (source_file_name_idx != 0) {
1768 u2 new_source_file_name_idx = find_new_index(source_file_name_idx);
1769 if (new_source_file_name_idx != 0) {
1770 scratch_class->set_source_file_name_index(new_source_file_name_idx);
1771 }
1772 }
1773
1774 // rewrite class generic signature index:
1775 u2 generic_signature_index = scratch_class->generic_signature_index();
1776 if (generic_signature_index != 0) {
1777 u2 new_generic_signature_index = find_new_index(generic_signature_index);
1778 if (new_generic_signature_index != 0) {
1779 scratch_class->set_generic_signature_index(new_generic_signature_index);
1780 }
1781 }
1782
1783 return true;
1784 } // end rewrite_cp_refs()
1785
1786 // Rewrite constant pool references in the NestHost and NestMembers attributes.
1787 bool VM_RedefineClasses::rewrite_cp_refs_in_nest_attributes(
1788 InstanceKlass* scratch_class) {
1789
1790 u2 cp_index = scratch_class->nest_host_index();
1791 if (cp_index != 0) {
1792 scratch_class->set_nest_host_index(find_new_index(cp_index));
1793 }
1794 Array<u2>* nest_members = scratch_class->nest_members();
1795 for (int i = 0; i < nest_members->length(); i++) {
1796 u2 cp_index = nest_members->at(i);
1797 nest_members->at_put(i, find_new_index(cp_index));
1798 }
1799 return true;
1800 }
1801
1802 // Rewrite constant pool references in the methods.
1803 bool VM_RedefineClasses::rewrite_cp_refs_in_methods(
1804 InstanceKlass* scratch_class, TRAPS) {
1805
1806 Array<Method*>* methods = scratch_class->methods();
1807
1808 if (methods == NULL || methods->length() == 0) {
1809 // no methods so nothing to do
1810 return true;
1811 }
1812
1813 // rewrite constant pool references in the methods:
1814 for (int i = methods->length() - 1; i >= 0; i--) {
1815 methodHandle method(THREAD, methods->at(i));
1816 methodHandle new_method;
1817 rewrite_cp_refs_in_method(method, &new_method, THREAD);
1818 if (!new_method.is_null()) {
1819 // the method has been replaced so save the new method version
1820 // even in the case of an exception. original method is on the
1821 // deallocation list.
1822 methods->at_put(i, new_method());
1823 }
1824 if (HAS_PENDING_EXCEPTION) {
1825 Symbol* ex_name = PENDING_EXCEPTION->klass()->name();
1826 log_info(redefine, class, load, exceptions)("rewrite_cp_refs_in_method exception: '%s'", ex_name->as_C_string());
1827 // Need to clear pending exception here as the super caller sets
1828 // the JVMTI_ERROR_INTERNAL if the returned value is false.
1829 CLEAR_PENDING_EXCEPTION;
1830 return false;
1831 }
1832 }
1833
1834 return true;
1835 }
1836
1837
1838 // Rewrite constant pool references in the specific method. This code
1839 // was adapted from Rewriter::rewrite_method().
1840 void VM_RedefineClasses::rewrite_cp_refs_in_method(methodHandle method,
1841 methodHandle *new_method_p, TRAPS) {
1842
1843 *new_method_p = methodHandle(); // default is no new method
1844
1845 // We cache a pointer to the bytecodes here in code_base. If GC
1846 // moves the Method*, then the bytecodes will also move which
1847 // will likely cause a crash. We create a NoSafepointVerifier
1848 // object to detect whether we pass a possible safepoint in this
1849 // code block.
1850 NoSafepointVerifier nsv;
1851
1852 // Bytecodes and their length
1853 address code_base = method->code_base();
1854 int code_length = method->code_size();
1855
1856 int bc_length;
1857 for (int bci = 0; bci < code_length; bci += bc_length) {
1858 address bcp = code_base + bci;
1859 Bytecodes::Code c = (Bytecodes::Code)(*bcp);
1860
1861 bc_length = Bytecodes::length_for(c);
1862 if (bc_length == 0) {
1863 // More complicated bytecodes report a length of zero so
1864 // we have to try again a slightly different way.
1865 bc_length = Bytecodes::length_at(method(), bcp);
1866 }
1867
1868 assert(bc_length != 0, "impossible bytecode length");
1869
1870 switch (c) {
1871 case Bytecodes::_ldc:
1872 {
1873 int cp_index = *(bcp + 1);
1874 int new_index = find_new_index(cp_index);
1875
1876 if (StressLdcRewrite && new_index == 0) {
1877 // If we are stressing ldc -> ldc_w rewriting, then we
1878 // always need a new_index value.
1879 new_index = cp_index;
1880 }
1881 if (new_index != 0) {
1882 // the original index is mapped so we have more work to do
1883 if (!StressLdcRewrite && new_index <= max_jubyte) {
1884 // The new value can still use ldc instead of ldc_w
1885 // unless we are trying to stress ldc -> ldc_w rewriting
1886 log_trace(redefine, class, constantpool)
1887 ("%s@" INTPTR_FORMAT " old=%d, new=%d", Bytecodes::name(c), p2i(bcp), cp_index, new_index);
1888 *(bcp + 1) = new_index;
1889 } else {
1890 log_trace(redefine, class, constantpool)
1891 ("%s->ldc_w@" INTPTR_FORMAT " old=%d, new=%d", Bytecodes::name(c), p2i(bcp), cp_index, new_index);
1892 // the new value needs ldc_w instead of ldc
1893 u_char inst_buffer[4]; // max instruction size is 4 bytes
1894 bcp = (address)inst_buffer;
1895 // construct new instruction sequence
1896 *bcp = Bytecodes::_ldc_w;
1897 bcp++;
1898 // Rewriter::rewrite_method() does not rewrite ldc -> ldc_w.
1899 // See comment below for difference between put_Java_u2()
1900 // and put_native_u2().
1901 Bytes::put_Java_u2(bcp, new_index);
1902
1903 Relocator rc(method, NULL /* no RelocatorListener needed */);
1904 methodHandle m;
1905 {
1906 PauseNoSafepointVerifier pnsv(&nsv);
1907
1908 // ldc is 2 bytes and ldc_w is 3 bytes
1909 m = rc.insert_space_at(bci, 3, inst_buffer, CHECK);
1910 }
1911
1912 // return the new method so that the caller can update
1913 // the containing class
1914 *new_method_p = method = m;
1915 // switch our bytecode processing loop from the old method
1916 // to the new method
1917 code_base = method->code_base();
1918 code_length = method->code_size();
1919 bcp = code_base + bci;
1920 c = (Bytecodes::Code)(*bcp);
1921 bc_length = Bytecodes::length_for(c);
1922 assert(bc_length != 0, "sanity check");
1923 } // end we need ldc_w instead of ldc
1924 } // end if there is a mapped index
1925 } break;
1926
1927 // these bytecodes have a two-byte constant pool index
1928 case Bytecodes::_anewarray : // fall through
1929 case Bytecodes::_checkcast : // fall through
1930 case Bytecodes::_getfield : // fall through
1931 case Bytecodes::_getstatic : // fall through
1932 case Bytecodes::_instanceof : // fall through
1933 case Bytecodes::_invokedynamic : // fall through
1934 case Bytecodes::_invokeinterface: // fall through
1935 case Bytecodes::_invokespecial : // fall through
1936 case Bytecodes::_invokestatic : // fall through
1937 case Bytecodes::_invokevirtual : // fall through
1938 case Bytecodes::_ldc_w : // fall through
1939 case Bytecodes::_ldc2_w : // fall through
1940 case Bytecodes::_multianewarray : // fall through
1941 case Bytecodes::_new : // fall through
1942 case Bytecodes::_putfield : // fall through
1943 case Bytecodes::_putstatic :
1944 {
1945 address p = bcp + 1;
1946 int cp_index = Bytes::get_Java_u2(p);
1947 int new_index = find_new_index(cp_index);
1948 if (new_index != 0) {
1949 // the original index is mapped so update w/ new value
1950 log_trace(redefine, class, constantpool)
1951 ("%s@" INTPTR_FORMAT " old=%d, new=%d", Bytecodes::name(c),p2i(bcp), cp_index, new_index);
1952 // Rewriter::rewrite_method() uses put_native_u2() in this
1953 // situation because it is reusing the constant pool index
1954 // location for a native index into the ConstantPoolCache.
1955 // Since we are updating the constant pool index prior to
1956 // verification and ConstantPoolCache initialization, we
1957 // need to keep the new index in Java byte order.
1958 Bytes::put_Java_u2(p, new_index);
1959 }
1960 } break;
1961 default:
1962 break;
1963 }
1964 } // end for each bytecode
1965
1966 // We also need to rewrite the parameter name indexes, if there is
1967 // method parameter data present
1968 if(method->has_method_parameters()) {
1969 const int len = method->method_parameters_length();
1970 MethodParametersElement* elem = method->method_parameters_start();
1971
1972 for (int i = 0; i < len; i++) {
1973 const u2 cp_index = elem[i].name_cp_index;
1974 const u2 new_cp_index = find_new_index(cp_index);
1975 if (new_cp_index != 0) {
1976 elem[i].name_cp_index = new_cp_index;
1977 }
1978 }
1979 }
1980 } // end rewrite_cp_refs_in_method()
1981
1982
1983 // Rewrite constant pool references in the class_annotations field.
1984 bool VM_RedefineClasses::rewrite_cp_refs_in_class_annotations(
1985 InstanceKlass* scratch_class, TRAPS) {
1986
1987 AnnotationArray* class_annotations = scratch_class->class_annotations();
1988 if (class_annotations == NULL || class_annotations->length() == 0) {
1989 // no class_annotations so nothing to do
1990 return true;
1991 }
1992
1993 log_debug(redefine, class, annotation)("class_annotations length=%d", class_annotations->length());
1994
1995 int byte_i = 0; // byte index into class_annotations
1996 return rewrite_cp_refs_in_annotations_typeArray(class_annotations, byte_i,
1997 THREAD);
1998 }
1999
2000
2001 // Rewrite constant pool references in an annotations typeArray. This
2002 // "structure" is adapted from the RuntimeVisibleAnnotations_attribute
2003 // that is described in section 4.8.15 of the 2nd-edition of the VM spec:
2004 //
2005 // annotations_typeArray {
2006 // u2 num_annotations;
2007 // annotation annotations[num_annotations];
2008 // }
2009 //
2010 bool VM_RedefineClasses::rewrite_cp_refs_in_annotations_typeArray(
2011 AnnotationArray* annotations_typeArray, int &byte_i_ref, TRAPS) {
2012
2013 if ((byte_i_ref + 2) > annotations_typeArray->length()) {
2014 // not enough room for num_annotations field
2015 log_debug(redefine, class, annotation)("length() is too small for num_annotations field");
2016 return false;
2017 }
2018
2019 u2 num_annotations = Bytes::get_Java_u2((address)
2020 annotations_typeArray->adr_at(byte_i_ref));
2021 byte_i_ref += 2;
2022
2023 log_debug(redefine, class, annotation)("num_annotations=%d", num_annotations);
2024
2025 int calc_num_annotations = 0;
2026 for (; calc_num_annotations < num_annotations; calc_num_annotations++) {
2027 if (!rewrite_cp_refs_in_annotation_struct(annotations_typeArray,
2028 byte_i_ref, THREAD)) {
2029 log_debug(redefine, class, annotation)("bad annotation_struct at %d", calc_num_annotations);
2030 // propagate failure back to caller
2031 return false;
2032 }
2033 }
2034 assert(num_annotations == calc_num_annotations, "sanity check");
2035
2036 return true;
2037 } // end rewrite_cp_refs_in_annotations_typeArray()
2038
2039
2040 // Rewrite constant pool references in the annotation struct portion of
2041 // an annotations_typeArray. This "structure" is from section 4.8.15 of
2042 // the 2nd-edition of the VM spec:
2043 //
2044 // struct annotation {
2045 // u2 type_index;
2046 // u2 num_element_value_pairs;
2047 // {
2048 // u2 element_name_index;
2049 // element_value value;
2050 // } element_value_pairs[num_element_value_pairs];
2051 // }
2052 //
2053 bool VM_RedefineClasses::rewrite_cp_refs_in_annotation_struct(
2054 AnnotationArray* annotations_typeArray, int &byte_i_ref, TRAPS) {
2055 if ((byte_i_ref + 2 + 2) > annotations_typeArray->length()) {
2056 // not enough room for smallest annotation_struct
2057 log_debug(redefine, class, annotation)("length() is too small for annotation_struct");
2058 return false;
2059 }
2060
2061 u2 type_index = rewrite_cp_ref_in_annotation_data(annotations_typeArray,
2062 byte_i_ref, "type_index", THREAD);
2063
2064 u2 num_element_value_pairs = Bytes::get_Java_u2((address)
2065 annotations_typeArray->adr_at(byte_i_ref));
2066 byte_i_ref += 2;
2067
2068 log_debug(redefine, class, annotation)
2069 ("type_index=%d num_element_value_pairs=%d", type_index, num_element_value_pairs);
2070
2071 int calc_num_element_value_pairs = 0;
2072 for (; calc_num_element_value_pairs < num_element_value_pairs;
2073 calc_num_element_value_pairs++) {
2074 if ((byte_i_ref + 2) > annotations_typeArray->length()) {
2075 // not enough room for another element_name_index, let alone
2076 // the rest of another component
2077 log_debug(redefine, class, annotation)("length() is too small for element_name_index");
2078 return false;
2079 }
2080
2081 u2 element_name_index = rewrite_cp_ref_in_annotation_data(
2082 annotations_typeArray, byte_i_ref,
2083 "element_name_index", THREAD);
2084
2085 log_debug(redefine, class, annotation)("element_name_index=%d", element_name_index);
2086
2087 if (!rewrite_cp_refs_in_element_value(annotations_typeArray,
2088 byte_i_ref, THREAD)) {
2089 log_debug(redefine, class, annotation)("bad element_value at %d", calc_num_element_value_pairs);
2090 // propagate failure back to caller
2091 return false;
2092 }
2093 } // end for each component
2094 assert(num_element_value_pairs == calc_num_element_value_pairs,
2095 "sanity check");
2096
2097 return true;
2098 } // end rewrite_cp_refs_in_annotation_struct()
2099
2100
2101 // Rewrite a constant pool reference at the current position in
2102 // annotations_typeArray if needed. Returns the original constant
2103 // pool reference if a rewrite was not needed or the new constant
2104 // pool reference if a rewrite was needed.
2105 u2 VM_RedefineClasses::rewrite_cp_ref_in_annotation_data(
2106 AnnotationArray* annotations_typeArray, int &byte_i_ref,
2107 const char * trace_mesg, TRAPS) {
2108
2109 address cp_index_addr = (address)
2110 annotations_typeArray->adr_at(byte_i_ref);
2111 u2 old_cp_index = Bytes::get_Java_u2(cp_index_addr);
2112 u2 new_cp_index = find_new_index(old_cp_index);
2113 if (new_cp_index != 0) {
2114 log_debug(redefine, class, annotation)("mapped old %s=%d", trace_mesg, old_cp_index);
2115 Bytes::put_Java_u2(cp_index_addr, new_cp_index);
2116 old_cp_index = new_cp_index;
2117 }
2118 byte_i_ref += 2;
2119 return old_cp_index;
2120 }
2121
2122
2123 // Rewrite constant pool references in the element_value portion of an
2124 // annotations_typeArray. This "structure" is from section 4.8.15.1 of
2125 // the 2nd-edition of the VM spec:
2126 //
2127 // struct element_value {
2128 // u1 tag;
2129 // union {
2130 // u2 const_value_index;
2131 // {
2132 // u2 type_name_index;
2133 // u2 const_name_index;
2134 // } enum_const_value;
2135 // u2 class_info_index;
2136 // annotation annotation_value;
2137 // struct {
2138 // u2 num_values;
2139 // element_value values[num_values];
2140 // } array_value;
2141 // } value;
2142 // }
2143 //
2144 bool VM_RedefineClasses::rewrite_cp_refs_in_element_value(
2145 AnnotationArray* annotations_typeArray, int &byte_i_ref, TRAPS) {
2146
2147 if ((byte_i_ref + 1) > annotations_typeArray->length()) {
2148 // not enough room for a tag let alone the rest of an element_value
2149 log_debug(redefine, class, annotation)("length() is too small for a tag");
2150 return false;
2151 }
2152
2153 u1 tag = annotations_typeArray->at(byte_i_ref);
2154 byte_i_ref++;
2155 log_debug(redefine, class, annotation)("tag='%c'", tag);
2156
2157 switch (tag) {
2158 // These BaseType tag values are from Table 4.2 in VM spec:
2159 case 'B': // byte
2160 case 'C': // char
2161 case 'D': // double
2162 case 'F': // float
2163 case 'I': // int
2164 case 'J': // long
2165 case 'S': // short
2166 case 'Z': // boolean
2167
2168 // The remaining tag values are from Table 4.8 in the 2nd-edition of
2169 // the VM spec:
2170 case 's':
2171 {
2172 // For the above tag values (including the BaseType values),
2173 // value.const_value_index is right union field.
2174
2175 if ((byte_i_ref + 2) > annotations_typeArray->length()) {
2176 // not enough room for a const_value_index
2177 log_debug(redefine, class, annotation)("length() is too small for a const_value_index");
2178 return false;
2179 }
2180
2181 u2 const_value_index = rewrite_cp_ref_in_annotation_data(
2182 annotations_typeArray, byte_i_ref,
2183 "const_value_index", THREAD);
2184
2185 log_debug(redefine, class, annotation)("const_value_index=%d", const_value_index);
2186 } break;
2187
2188 case 'e':
2189 {
2190 // for the above tag value, value.enum_const_value is right union field
2191
2192 if ((byte_i_ref + 4) > annotations_typeArray->length()) {
2193 // not enough room for a enum_const_value
2194 log_debug(redefine, class, annotation)("length() is too small for a enum_const_value");
2195 return false;
2196 }
2197
2198 u2 type_name_index = rewrite_cp_ref_in_annotation_data(
2199 annotations_typeArray, byte_i_ref,
2200 "type_name_index", THREAD);
2201
2202 u2 const_name_index = rewrite_cp_ref_in_annotation_data(
2203 annotations_typeArray, byte_i_ref,
2204 "const_name_index", THREAD);
2205
2206 log_debug(redefine, class, annotation)
2207 ("type_name_index=%d const_name_index=%d", type_name_index, const_name_index);
2208 } break;
2209
2210 case 'c':
2211 {
2212 // for the above tag value, value.class_info_index is right union field
2213
2214 if ((byte_i_ref + 2) > annotations_typeArray->length()) {
2215 // not enough room for a class_info_index
2216 log_debug(redefine, class, annotation)("length() is too small for a class_info_index");
2217 return false;
2218 }
2219
2220 u2 class_info_index = rewrite_cp_ref_in_annotation_data(
2221 annotations_typeArray, byte_i_ref,
2222 "class_info_index", THREAD);
2223
2224 log_debug(redefine, class, annotation)("class_info_index=%d", class_info_index);
2225 } break;
2226
2227 case '@':
2228 // For the above tag value, value.attr_value is the right union
2229 // field. This is a nested annotation.
2230 if (!rewrite_cp_refs_in_annotation_struct(annotations_typeArray,
2231 byte_i_ref, THREAD)) {
2232 // propagate failure back to caller
2233 return false;
2234 }
2235 break;
2236
2237 case '[':
2238 {
2239 if ((byte_i_ref + 2) > annotations_typeArray->length()) {
2240 // not enough room for a num_values field
2241 log_debug(redefine, class, annotation)("length() is too small for a num_values field");
2242 return false;
2243 }
2244
2245 // For the above tag value, value.array_value is the right union
2246 // field. This is an array of nested element_value.
2247 u2 num_values = Bytes::get_Java_u2((address)
2248 annotations_typeArray->adr_at(byte_i_ref));
2249 byte_i_ref += 2;
2250 log_debug(redefine, class, annotation)("num_values=%d", num_values);
2251
2252 int calc_num_values = 0;
2253 for (; calc_num_values < num_values; calc_num_values++) {
2254 if (!rewrite_cp_refs_in_element_value(
2255 annotations_typeArray, byte_i_ref, THREAD)) {
2256 log_debug(redefine, class, annotation)("bad nested element_value at %d", calc_num_values);
2257 // propagate failure back to caller
2258 return false;
2259 }
2260 }
2261 assert(num_values == calc_num_values, "sanity check");
2262 } break;
2263
2264 default:
2265 log_debug(redefine, class, annotation)("bad tag=0x%x", tag);
2266 return false;
2267 } // end decode tag field
2268
2269 return true;
2270 } // end rewrite_cp_refs_in_element_value()
2271
2272
2273 // Rewrite constant pool references in a fields_annotations field.
2274 bool VM_RedefineClasses::rewrite_cp_refs_in_fields_annotations(
2275 InstanceKlass* scratch_class, TRAPS) {
2276
2277 Array<AnnotationArray*>* fields_annotations = scratch_class->fields_annotations();
2278
2279 if (fields_annotations == NULL || fields_annotations->length() == 0) {
2280 // no fields_annotations so nothing to do
2281 return true;
2282 }
2283
2284 log_debug(redefine, class, annotation)("fields_annotations length=%d", fields_annotations->length());
2285
2286 for (int i = 0; i < fields_annotations->length(); i++) {
2287 AnnotationArray* field_annotations = fields_annotations->at(i);
2288 if (field_annotations == NULL || field_annotations->length() == 0) {
2289 // this field does not have any annotations so skip it
2290 continue;
2291 }
2292
2293 int byte_i = 0; // byte index into field_annotations
2294 if (!rewrite_cp_refs_in_annotations_typeArray(field_annotations, byte_i,
2295 THREAD)) {
2296 log_debug(redefine, class, annotation)("bad field_annotations at %d", i);
2297 // propagate failure back to caller
2298 return false;
2299 }
2300 }
2301
2302 return true;
2303 } // end rewrite_cp_refs_in_fields_annotations()
2304
2305
2306 // Rewrite constant pool references in a methods_annotations field.
2307 bool VM_RedefineClasses::rewrite_cp_refs_in_methods_annotations(
2308 InstanceKlass* scratch_class, TRAPS) {
2309
2310 for (int i = 0; i < scratch_class->methods()->length(); i++) {
2311 Method* m = scratch_class->methods()->at(i);
2312 AnnotationArray* method_annotations = m->constMethod()->method_annotations();
2313
2314 if (method_annotations == NULL || method_annotations->length() == 0) {
2315 // this method does not have any annotations so skip it
2316 continue;
2317 }
2318
2319 int byte_i = 0; // byte index into method_annotations
2320 if (!rewrite_cp_refs_in_annotations_typeArray(method_annotations, byte_i,
2321 THREAD)) {
2322 log_debug(redefine, class, annotation)("bad method_annotations at %d", i);
2323 // propagate failure back to caller
2324 return false;
2325 }
2326 }
2327
2328 return true;
2329 } // end rewrite_cp_refs_in_methods_annotations()
2330
2331
2332 // Rewrite constant pool references in a methods_parameter_annotations
2333 // field. This "structure" is adapted from the
2334 // RuntimeVisibleParameterAnnotations_attribute described in section
2335 // 4.8.17 of the 2nd-edition of the VM spec:
2336 //
2337 // methods_parameter_annotations_typeArray {
2338 // u1 num_parameters;
2339 // {
2340 // u2 num_annotations;
2341 // annotation annotations[num_annotations];
2342 // } parameter_annotations[num_parameters];
2343 // }
2344 //
2345 bool VM_RedefineClasses::rewrite_cp_refs_in_methods_parameter_annotations(
2346 InstanceKlass* scratch_class, TRAPS) {
2347
2348 for (int i = 0; i < scratch_class->methods()->length(); i++) {
2349 Method* m = scratch_class->methods()->at(i);
2350 AnnotationArray* method_parameter_annotations = m->constMethod()->parameter_annotations();
2351 if (method_parameter_annotations == NULL
2352 || method_parameter_annotations->length() == 0) {
2353 // this method does not have any parameter annotations so skip it
2354 continue;
2355 }
2356
2357 if (method_parameter_annotations->length() < 1) {
2358 // not enough room for a num_parameters field
2359 log_debug(redefine, class, annotation)("length() is too small for a num_parameters field at %d", i);
2360 return false;
2361 }
2362
2363 int byte_i = 0; // byte index into method_parameter_annotations
2364
2365 u1 num_parameters = method_parameter_annotations->at(byte_i);
2366 byte_i++;
2367
2368 log_debug(redefine, class, annotation)("num_parameters=%d", num_parameters);
2369
2370 int calc_num_parameters = 0;
2371 for (; calc_num_parameters < num_parameters; calc_num_parameters++) {
2372 if (!rewrite_cp_refs_in_annotations_typeArray(
2373 method_parameter_annotations, byte_i, THREAD)) {
2374 log_debug(redefine, class, annotation)("bad method_parameter_annotations at %d", calc_num_parameters);
2375 // propagate failure back to caller
2376 return false;
2377 }
2378 }
2379 assert(num_parameters == calc_num_parameters, "sanity check");
2380 }
2381
2382 return true;
2383 } // end rewrite_cp_refs_in_methods_parameter_annotations()
2384
2385
2386 // Rewrite constant pool references in a methods_default_annotations
2387 // field. This "structure" is adapted from the AnnotationDefault_attribute
2388 // that is described in section 4.8.19 of the 2nd-edition of the VM spec:
2389 //
2390 // methods_default_annotations_typeArray {
2391 // element_value default_value;
2392 // }
2393 //
2394 bool VM_RedefineClasses::rewrite_cp_refs_in_methods_default_annotations(
2395 InstanceKlass* scratch_class, TRAPS) {
2396
2397 for (int i = 0; i < scratch_class->methods()->length(); i++) {
2398 Method* m = scratch_class->methods()->at(i);
2399 AnnotationArray* method_default_annotations = m->constMethod()->default_annotations();
2400 if (method_default_annotations == NULL
2401 || method_default_annotations->length() == 0) {
2402 // this method does not have any default annotations so skip it
2403 continue;
2404 }
2405
2406 int byte_i = 0; // byte index into method_default_annotations
2407
2408 if (!rewrite_cp_refs_in_element_value(
2409 method_default_annotations, byte_i, THREAD)) {
2410 log_debug(redefine, class, annotation)("bad default element_value at %d", i);
2411 // propagate failure back to caller
2412 return false;
2413 }
2414 }
2415
2416 return true;
2417 } // end rewrite_cp_refs_in_methods_default_annotations()
2418
2419
2420 // Rewrite constant pool references in a class_type_annotations field.
2421 bool VM_RedefineClasses::rewrite_cp_refs_in_class_type_annotations(
2422 InstanceKlass* scratch_class, TRAPS) {
2423
2424 AnnotationArray* class_type_annotations = scratch_class->class_type_annotations();
2425 if (class_type_annotations == NULL || class_type_annotations->length() == 0) {
2426 // no class_type_annotations so nothing to do
2427 return true;
2428 }
2429
2430 log_debug(redefine, class, annotation)("class_type_annotations length=%d", class_type_annotations->length());
2431
2432 int byte_i = 0; // byte index into class_type_annotations
2433 return rewrite_cp_refs_in_type_annotations_typeArray(class_type_annotations,
2434 byte_i, "ClassFile", THREAD);
2435 } // end rewrite_cp_refs_in_class_type_annotations()
2436
2437
2438 // Rewrite constant pool references in a fields_type_annotations field.
2439 bool VM_RedefineClasses::rewrite_cp_refs_in_fields_type_annotations(
2440 InstanceKlass* scratch_class, TRAPS) {
2441
2442 Array<AnnotationArray*>* fields_type_annotations = scratch_class->fields_type_annotations();
2443 if (fields_type_annotations == NULL || fields_type_annotations->length() == 0) {
2444 // no fields_type_annotations so nothing to do
2445 return true;
2446 }
2447
2448 log_debug(redefine, class, annotation)("fields_type_annotations length=%d", fields_type_annotations->length());
2449
2450 for (int i = 0; i < fields_type_annotations->length(); i++) {
2451 AnnotationArray* field_type_annotations = fields_type_annotations->at(i);
2452 if (field_type_annotations == NULL || field_type_annotations->length() == 0) {
2453 // this field does not have any annotations so skip it
2454 continue;
2455 }
2456
2457 int byte_i = 0; // byte index into field_type_annotations
2458 if (!rewrite_cp_refs_in_type_annotations_typeArray(field_type_annotations,
2459 byte_i, "field_info", THREAD)) {
2460 log_debug(redefine, class, annotation)("bad field_type_annotations at %d", i);
2461 // propagate failure back to caller
2462 return false;
2463 }
2464 }
2465
2466 return true;
2467 } // end rewrite_cp_refs_in_fields_type_annotations()
2468
2469
2470 // Rewrite constant pool references in a methods_type_annotations field.
2471 bool VM_RedefineClasses::rewrite_cp_refs_in_methods_type_annotations(
2472 InstanceKlass* scratch_class, TRAPS) {
2473
2474 for (int i = 0; i < scratch_class->methods()->length(); i++) {
2475 Method* m = scratch_class->methods()->at(i);
2476 AnnotationArray* method_type_annotations = m->constMethod()->type_annotations();
2477
2478 if (method_type_annotations == NULL || method_type_annotations->length() == 0) {
2479 // this method does not have any annotations so skip it
2480 continue;
2481 }
2482
2483 log_debug(redefine, class, annotation)("methods type_annotations length=%d", method_type_annotations->length());
2484
2485 int byte_i = 0; // byte index into method_type_annotations
2486 if (!rewrite_cp_refs_in_type_annotations_typeArray(method_type_annotations,
2487 byte_i, "method_info", THREAD)) {
2488 log_debug(redefine, class, annotation)("bad method_type_annotations at %d", i);
2489 // propagate failure back to caller
2490 return false;
2491 }
2492 }
2493
2494 return true;
2495 } // end rewrite_cp_refs_in_methods_type_annotations()
2496
2497
2498 // Rewrite constant pool references in a type_annotations
2499 // field. This "structure" is adapted from the
2500 // RuntimeVisibleTypeAnnotations_attribute described in
2501 // section 4.7.20 of the Java SE 8 Edition of the VM spec:
2502 //
2503 // type_annotations_typeArray {
2504 // u2 num_annotations;
2505 // type_annotation annotations[num_annotations];
2506 // }
2507 //
2508 bool VM_RedefineClasses::rewrite_cp_refs_in_type_annotations_typeArray(
2509 AnnotationArray* type_annotations_typeArray, int &byte_i_ref,
2510 const char * location_mesg, TRAPS) {
2511
2512 if ((byte_i_ref + 2) > type_annotations_typeArray->length()) {
2513 // not enough room for num_annotations field
2514 log_debug(redefine, class, annotation)("length() is too small for num_annotations field");
2515 return false;
2516 }
2517
2518 u2 num_annotations = Bytes::get_Java_u2((address)
2519 type_annotations_typeArray->adr_at(byte_i_ref));
2520 byte_i_ref += 2;
2521
2522 log_debug(redefine, class, annotation)("num_type_annotations=%d", num_annotations);
2523
2524 int calc_num_annotations = 0;
2525 for (; calc_num_annotations < num_annotations; calc_num_annotations++) {
2526 if (!rewrite_cp_refs_in_type_annotation_struct(type_annotations_typeArray,
2527 byte_i_ref, location_mesg, THREAD)) {
2528 log_debug(redefine, class, annotation)("bad type_annotation_struct at %d", calc_num_annotations);
2529 // propagate failure back to caller
2530 return false;
2531 }
2532 }
2533 assert(num_annotations == calc_num_annotations, "sanity check");
2534
2535 if (byte_i_ref != type_annotations_typeArray->length()) {
2536 log_debug(redefine, class, annotation)
2537 ("read wrong amount of bytes at end of processing type_annotations_typeArray (%d of %d bytes were read)",
2538 byte_i_ref, type_annotations_typeArray->length());
2539 return false;
2540 }
2541
2542 return true;
2543 } // end rewrite_cp_refs_in_type_annotations_typeArray()
2544
2545
2546 // Rewrite constant pool references in a type_annotation
2547 // field. This "structure" is adapted from the
2548 // RuntimeVisibleTypeAnnotations_attribute described in
2549 // section 4.7.20 of the Java SE 8 Edition of the VM spec:
2550 //
2551 // type_annotation {
2552 // u1 target_type;
2553 // union {
2554 // type_parameter_target;
2555 // supertype_target;
2556 // type_parameter_bound_target;
2557 // empty_target;
2558 // method_formal_parameter_target;
2559 // throws_target;
2560 // localvar_target;
2561 // catch_target;
2562 // offset_target;
2563 // type_argument_target;
2564 // } target_info;
2565 // type_path target_path;
2566 // annotation anno;
2567 // }
2568 //
2569 bool VM_RedefineClasses::rewrite_cp_refs_in_type_annotation_struct(
2570 AnnotationArray* type_annotations_typeArray, int &byte_i_ref,
2571 const char * location_mesg, TRAPS) {
2572
2573 if (!skip_type_annotation_target(type_annotations_typeArray,
2574 byte_i_ref, location_mesg, THREAD)) {
2575 return false;
2576 }
2577
2578 if (!skip_type_annotation_type_path(type_annotations_typeArray,
2579 byte_i_ref, THREAD)) {
2580 return false;
2581 }
2582
2583 if (!rewrite_cp_refs_in_annotation_struct(type_annotations_typeArray,
2584 byte_i_ref, THREAD)) {
2585 return false;
2586 }
2587
2588 return true;
2589 } // end rewrite_cp_refs_in_type_annotation_struct()
2590
2591
2592 // Read, verify and skip over the target_type and target_info part
2593 // so that rewriting can continue in the later parts of the struct.
2594 //
2595 // u1 target_type;
2596 // union {
2597 // type_parameter_target;
2598 // supertype_target;
2599 // type_parameter_bound_target;
2600 // empty_target;
2601 // method_formal_parameter_target;
2602 // throws_target;
2603 // localvar_target;
2604 // catch_target;
2605 // offset_target;
2606 // type_argument_target;
2607 // } target_info;
2608 //
2609 bool VM_RedefineClasses::skip_type_annotation_target(
2610 AnnotationArray* type_annotations_typeArray, int &byte_i_ref,
2611 const char * location_mesg, TRAPS) {
2612
2613 if ((byte_i_ref + 1) > type_annotations_typeArray->length()) {
2614 // not enough room for a target_type let alone the rest of a type_annotation
2615 log_debug(redefine, class, annotation)("length() is too small for a target_type");
2616 return false;
2617 }
2618
2619 u1 target_type = type_annotations_typeArray->at(byte_i_ref);
2620 byte_i_ref += 1;
2621 log_debug(redefine, class, annotation)("target_type=0x%.2x", target_type);
2622 log_debug(redefine, class, annotation)("location=%s", location_mesg);
2623
2624 // Skip over target_info
2625 switch (target_type) {
2626 case 0x00:
2627 // kind: type parameter declaration of generic class or interface
2628 // location: ClassFile
2629 case 0x01:
2630 // kind: type parameter declaration of generic method or constructor
2631 // location: method_info
2632
2633 {
2634 // struct:
2635 // type_parameter_target {
2636 // u1 type_parameter_index;
2637 // }
2638 //
2639 if ((byte_i_ref + 1) > type_annotations_typeArray->length()) {
2640 log_debug(redefine, class, annotation)("length() is too small for a type_parameter_target");
2641 return false;
2642 }
2643
2644 u1 type_parameter_index = type_annotations_typeArray->at(byte_i_ref);
2645 byte_i_ref += 1;
2646
2647 log_debug(redefine, class, annotation)("type_parameter_target: type_parameter_index=%d", type_parameter_index);
2648 } break;
2649
2650 case 0x10:
2651 // kind: type in extends clause of class or interface declaration
2652 // (including the direct superclass of an unsafe anonymous class declaration),
2653 // or in implements clause of interface declaration
2654 // location: ClassFile
2655
2656 {
2657 // struct:
2658 // supertype_target {
2659 // u2 supertype_index;
2660 // }
2661 //
2662 if ((byte_i_ref + 2) > type_annotations_typeArray->length()) {
2663 log_debug(redefine, class, annotation)("length() is too small for a supertype_target");
2664 return false;
2665 }
2666
2667 u2 supertype_index = Bytes::get_Java_u2((address)
2668 type_annotations_typeArray->adr_at(byte_i_ref));
2669 byte_i_ref += 2;
2670
2671 log_debug(redefine, class, annotation)("supertype_target: supertype_index=%d", supertype_index);
2672 } break;
2673
2674 case 0x11:
2675 // kind: type in bound of type parameter declaration of generic class or interface
2676 // location: ClassFile
2677 case 0x12:
2678 // kind: type in bound of type parameter declaration of generic method or constructor
2679 // location: method_info
2680
2681 {
2682 // struct:
2683 // type_parameter_bound_target {
2684 // u1 type_parameter_index;
2685 // u1 bound_index;
2686 // }
2687 //
2688 if ((byte_i_ref + 2) > type_annotations_typeArray->length()) {
2689 log_debug(redefine, class, annotation)("length() is too small for a type_parameter_bound_target");
2690 return false;
2691 }
2692
2693 u1 type_parameter_index = type_annotations_typeArray->at(byte_i_ref);
2694 byte_i_ref += 1;
2695 u1 bound_index = type_annotations_typeArray->at(byte_i_ref);
2696 byte_i_ref += 1;
2697
2698 log_debug(redefine, class, annotation)
2699 ("type_parameter_bound_target: type_parameter_index=%d, bound_index=%d", type_parameter_index, bound_index);
2700 } break;
2701
2702 case 0x13:
2703 // kind: type in field declaration
2704 // location: field_info
2705 case 0x14:
2706 // kind: return type of method, or type of newly constructed object
2707 // location: method_info
2708 case 0x15:
2709 // kind: receiver type of method or constructor
2710 // location: method_info
2711
2712 {
2713 // struct:
2714 // empty_target {
2715 // }
2716 //
2717 log_debug(redefine, class, annotation)("empty_target");
2718 } break;
2719
2720 case 0x16:
2721 // kind: type in formal parameter declaration of method, constructor, or lambda expression
2722 // location: method_info
2723
2724 {
2725 // struct:
2726 // formal_parameter_target {
2727 // u1 formal_parameter_index;
2728 // }
2729 //
2730 if ((byte_i_ref + 1) > type_annotations_typeArray->length()) {
2731 log_debug(redefine, class, annotation)("length() is too small for a formal_parameter_target");
2732 return false;
2733 }
2734
2735 u1 formal_parameter_index = type_annotations_typeArray->at(byte_i_ref);
2736 byte_i_ref += 1;
2737
2738 log_debug(redefine, class, annotation)
2739 ("formal_parameter_target: formal_parameter_index=%d", formal_parameter_index);
2740 } break;
2741
2742 case 0x17:
2743 // kind: type in throws clause of method or constructor
2744 // location: method_info
2745
2746 {
2747 // struct:
2748 // throws_target {
2749 // u2 throws_type_index
2750 // }
2751 //
2752 if ((byte_i_ref + 2) > type_annotations_typeArray->length()) {
2753 log_debug(redefine, class, annotation)("length() is too small for a throws_target");
2754 return false;
2755 }
2756
2757 u2 throws_type_index = Bytes::get_Java_u2((address)
2758 type_annotations_typeArray->adr_at(byte_i_ref));
2759 byte_i_ref += 2;
2760
2761 log_debug(redefine, class, annotation)("throws_target: throws_type_index=%d", throws_type_index);
2762 } break;
2763
2764 case 0x40:
2765 // kind: type in local variable declaration
2766 // location: Code
2767 case 0x41:
2768 // kind: type in resource variable declaration
2769 // location: Code
2770
2771 {
2772 // struct:
2773 // localvar_target {
2774 // u2 table_length;
2775 // struct {
2776 // u2 start_pc;
2777 // u2 length;
2778 // u2 index;
2779 // } table[table_length];
2780 // }
2781 //
2782 if ((byte_i_ref + 2) > type_annotations_typeArray->length()) {
2783 // not enough room for a table_length let alone the rest of a localvar_target
2784 log_debug(redefine, class, annotation)("length() is too small for a localvar_target table_length");
2785 return false;
2786 }
2787
2788 u2 table_length = Bytes::get_Java_u2((address)
2789 type_annotations_typeArray->adr_at(byte_i_ref));
2790 byte_i_ref += 2;
2791
2792 log_debug(redefine, class, annotation)("localvar_target: table_length=%d", table_length);
2793
2794 int table_struct_size = 2 + 2 + 2; // 3 u2 variables per table entry
2795 int table_size = table_length * table_struct_size;
2796
2797 if ((byte_i_ref + table_size) > type_annotations_typeArray->length()) {
2798 // not enough room for a table
2799 log_debug(redefine, class, annotation)("length() is too small for a table array of length %d", table_length);
2800 return false;
2801 }
2802
2803 // Skip over table
2804 byte_i_ref += table_size;
2805 } break;
2806
2807 case 0x42:
2808 // kind: type in exception parameter declaration
2809 // location: Code
2810
2811 {
2812 // struct:
2813 // catch_target {
2814 // u2 exception_table_index;
2815 // }
2816 //
2817 if ((byte_i_ref + 2) > type_annotations_typeArray->length()) {
2818 log_debug(redefine, class, annotation)("length() is too small for a catch_target");
2819 return false;
2820 }
2821
2822 u2 exception_table_index = Bytes::get_Java_u2((address)
2823 type_annotations_typeArray->adr_at(byte_i_ref));
2824 byte_i_ref += 2;
2825
2826 log_debug(redefine, class, annotation)("catch_target: exception_table_index=%d", exception_table_index);
2827 } break;
2828
2829 case 0x43:
2830 // kind: type in instanceof expression
2831 // location: Code
2832 case 0x44:
2833 // kind: type in new expression
2834 // location: Code
2835 case 0x45:
2836 // kind: type in method reference expression using ::new
2837 // location: Code
2838 case 0x46:
2839 // kind: type in method reference expression using ::Identifier
2840 // location: Code
2841
2842 {
2843 // struct:
2844 // offset_target {
2845 // u2 offset;
2846 // }
2847 //
2848 if ((byte_i_ref + 2) > type_annotations_typeArray->length()) {
2849 log_debug(redefine, class, annotation)("length() is too small for a offset_target");
2850 return false;
2851 }
2852
2853 u2 offset = Bytes::get_Java_u2((address)
2854 type_annotations_typeArray->adr_at(byte_i_ref));
2855 byte_i_ref += 2;
2856
2857 log_debug(redefine, class, annotation)("offset_target: offset=%d", offset);
2858 } break;
2859
2860 case 0x47:
2861 // kind: type in cast expression
2862 // location: Code
2863 case 0x48:
2864 // kind: type argument for generic constructor in new expression or
2865 // explicit constructor invocation statement
2866 // location: Code
2867 case 0x49:
2868 // kind: type argument for generic method in method invocation expression
2869 // location: Code
2870 case 0x4A:
2871 // kind: type argument for generic constructor in method reference expression using ::new
2872 // location: Code
2873 case 0x4B:
2874 // kind: type argument for generic method in method reference expression using ::Identifier
2875 // location: Code
2876
2877 {
2878 // struct:
2879 // type_argument_target {
2880 // u2 offset;
2881 // u1 type_argument_index;
2882 // }
2883 //
2884 if ((byte_i_ref + 3) > type_annotations_typeArray->length()) {
2885 log_debug(redefine, class, annotation)("length() is too small for a type_argument_target");
2886 return false;
2887 }
2888
2889 u2 offset = Bytes::get_Java_u2((address)
2890 type_annotations_typeArray->adr_at(byte_i_ref));
2891 byte_i_ref += 2;
2892 u1 type_argument_index = type_annotations_typeArray->at(byte_i_ref);
2893 byte_i_ref += 1;
2894
2895 log_debug(redefine, class, annotation)
2896 ("type_argument_target: offset=%d, type_argument_index=%d", offset, type_argument_index);
2897 } break;
2898
2899 default:
2900 log_debug(redefine, class, annotation)("unknown target_type");
2901 #ifdef ASSERT
2902 ShouldNotReachHere();
2903 #endif
2904 return false;
2905 }
2906
2907 return true;
2908 } // end skip_type_annotation_target()
2909
2910
2911 // Read, verify and skip over the type_path part so that rewriting
2912 // can continue in the later parts of the struct.
2913 //
2914 // type_path {
2915 // u1 path_length;
2916 // {
2917 // u1 type_path_kind;
2918 // u1 type_argument_index;
2919 // } path[path_length];
2920 // }
2921 //
2922 bool VM_RedefineClasses::skip_type_annotation_type_path(
2923 AnnotationArray* type_annotations_typeArray, int &byte_i_ref, TRAPS) {
2924
2925 if ((byte_i_ref + 1) > type_annotations_typeArray->length()) {
2926 // not enough room for a path_length let alone the rest of the type_path
2927 log_debug(redefine, class, annotation)("length() is too small for a type_path");
2928 return false;
2929 }
2930
2931 u1 path_length = type_annotations_typeArray->at(byte_i_ref);
2932 byte_i_ref += 1;
2933
2934 log_debug(redefine, class, annotation)("type_path: path_length=%d", path_length);
2935
2936 int calc_path_length = 0;
2937 for (; calc_path_length < path_length; calc_path_length++) {
2938 if ((byte_i_ref + 1 + 1) > type_annotations_typeArray->length()) {
2939 // not enough room for a path
2940 log_debug(redefine, class, annotation)
2941 ("length() is too small for path entry %d of %d", calc_path_length, path_length);
2942 return false;
2943 }
2944
2945 u1 type_path_kind = type_annotations_typeArray->at(byte_i_ref);
2946 byte_i_ref += 1;
2947 u1 type_argument_index = type_annotations_typeArray->at(byte_i_ref);
2948 byte_i_ref += 1;
2949
2950 log_debug(redefine, class, annotation)
2951 ("type_path: path[%d]: type_path_kind=%d, type_argument_index=%d",
2952 calc_path_length, type_path_kind, type_argument_index);
2953
2954 if (type_path_kind > 3 || (type_path_kind != 3 && type_argument_index != 0)) {
2955 // not enough room for a path
2956 log_debug(redefine, class, annotation)("inconsistent type_path values");
2957 return false;
2958 }
2959 }
2960 assert(path_length == calc_path_length, "sanity check");
2961
2962 return true;
2963 } // end skip_type_annotation_type_path()
2964
2965
2966 // Rewrite constant pool references in the method's stackmap table.
2967 // These "structures" are adapted from the StackMapTable_attribute that
2968 // is described in section 4.8.4 of the 6.0 version of the VM spec
2969 // (dated 2005.10.26):
2970 // file:///net/quincunx.sfbay/export/gbracha/ClassFile-Java6.pdf
2971 //
2972 // stack_map {
2973 // u2 number_of_entries;
2974 // stack_map_frame entries[number_of_entries];
2975 // }
2976 //
2977 void VM_RedefineClasses::rewrite_cp_refs_in_stack_map_table(
2978 const methodHandle& method, TRAPS) {
2979
2980 if (!method->has_stackmap_table()) {
2981 return;
2982 }
2983
2984 AnnotationArray* stackmap_data = method->stackmap_data();
2985 address stackmap_p = (address)stackmap_data->adr_at(0);
2986 address stackmap_end = stackmap_p + stackmap_data->length();
2987
2988 assert(stackmap_p + 2 <= stackmap_end, "no room for number_of_entries");
2989 u2 number_of_entries = Bytes::get_Java_u2(stackmap_p);
2990 stackmap_p += 2;
2991
2992 log_debug(redefine, class, stackmap)("number_of_entries=%u", number_of_entries);
2993
2994 // walk through each stack_map_frame
2995 u2 calc_number_of_entries = 0;
2996 for (; calc_number_of_entries < number_of_entries; calc_number_of_entries++) {
2997 // The stack_map_frame structure is a u1 frame_type followed by
2998 // 0 or more bytes of data:
2999 //
3000 // union stack_map_frame {
3001 // same_frame;
3002 // same_locals_1_stack_item_frame;
3003 // same_locals_1_stack_item_frame_extended;
3004 // chop_frame;
3005 // same_frame_extended;
3006 // append_frame;
3007 // full_frame;
3008 // }
3009
3010 assert(stackmap_p + 1 <= stackmap_end, "no room for frame_type");
3011 u1 frame_type = *stackmap_p;
3012 stackmap_p++;
3013
3014 // same_frame {
3015 // u1 frame_type = SAME; /* 0-63 */
3016 // }
3017 if (frame_type <= 63) {
3018 // nothing more to do for same_frame
3019 }
3020
3021 // same_locals_1_stack_item_frame {
3022 // u1 frame_type = SAME_LOCALS_1_STACK_ITEM; /* 64-127 */
3023 // verification_type_info stack[1];
3024 // }
3025 else if (frame_type >= 64 && frame_type <= 127) {
3026 rewrite_cp_refs_in_verification_type_info(stackmap_p, stackmap_end,
3027 calc_number_of_entries, frame_type, THREAD);
3028 }
3029
3030 // reserved for future use
3031 else if (frame_type >= 128 && frame_type <= 246) {
3032 // nothing more to do for reserved frame_types
3033 }
3034
3035 // same_locals_1_stack_item_frame_extended {
3036 // u1 frame_type = SAME_LOCALS_1_STACK_ITEM_EXTENDED; /* 247 */
3037 // u2 offset_delta;
3038 // verification_type_info stack[1];
3039 // }
3040 else if (frame_type == 247) {
3041 stackmap_p += 2;
3042 rewrite_cp_refs_in_verification_type_info(stackmap_p, stackmap_end,
3043 calc_number_of_entries, frame_type, THREAD);
3044 }
3045
3046 // chop_frame {
3047 // u1 frame_type = CHOP; /* 248-250 */
3048 // u2 offset_delta;
3049 // }
3050 else if (frame_type >= 248 && frame_type <= 250) {
3051 stackmap_p += 2;
3052 }
3053
3054 // same_frame_extended {
3055 // u1 frame_type = SAME_FRAME_EXTENDED; /* 251*/
3056 // u2 offset_delta;
3057 // }
3058 else if (frame_type == 251) {
3059 stackmap_p += 2;
3060 }
3061
3062 // append_frame {
3063 // u1 frame_type = APPEND; /* 252-254 */
3064 // u2 offset_delta;
3065 // verification_type_info locals[frame_type - 251];
3066 // }
3067 else if (frame_type >= 252 && frame_type <= 254) {
3068 assert(stackmap_p + 2 <= stackmap_end,
3069 "no room for offset_delta");
3070 stackmap_p += 2;
3071 u1 len = frame_type - 251;
3072 for (u1 i = 0; i < len; i++) {
3073 rewrite_cp_refs_in_verification_type_info(stackmap_p, stackmap_end,
3074 calc_number_of_entries, frame_type, THREAD);
3075 }
3076 }
3077
3078 // full_frame {
3079 // u1 frame_type = FULL_FRAME; /* 255 */
3080 // u2 offset_delta;
3081 // u2 number_of_locals;
3082 // verification_type_info locals[number_of_locals];
3083 // u2 number_of_stack_items;
3084 // verification_type_info stack[number_of_stack_items];
3085 // }
3086 else if (frame_type == 255) {
3087 assert(stackmap_p + 2 + 2 <= stackmap_end,
3088 "no room for smallest full_frame");
3089 stackmap_p += 2;
3090
3091 u2 number_of_locals = Bytes::get_Java_u2(stackmap_p);
3092 stackmap_p += 2;
3093
3094 for (u2 locals_i = 0; locals_i < number_of_locals; locals_i++) {
3095 rewrite_cp_refs_in_verification_type_info(stackmap_p, stackmap_end,
3096 calc_number_of_entries, frame_type, THREAD);
3097 }
3098
3099 // Use the largest size for the number_of_stack_items, but only get
3100 // the right number of bytes.
3101 u2 number_of_stack_items = Bytes::get_Java_u2(stackmap_p);
3102 stackmap_p += 2;
3103
3104 for (u2 stack_i = 0; stack_i < number_of_stack_items; stack_i++) {
3105 rewrite_cp_refs_in_verification_type_info(stackmap_p, stackmap_end,
3106 calc_number_of_entries, frame_type, THREAD);
3107 }
3108 }
3109 } // end while there is a stack_map_frame
3110 assert(number_of_entries == calc_number_of_entries, "sanity check");
3111 } // end rewrite_cp_refs_in_stack_map_table()
3112
3113
3114 // Rewrite constant pool references in the verification type info
3115 // portion of the method's stackmap table. These "structures" are
3116 // adapted from the StackMapTable_attribute that is described in
3117 // section 4.8.4 of the 6.0 version of the VM spec (dated 2005.10.26):
3118 // file:///net/quincunx.sfbay/export/gbracha/ClassFile-Java6.pdf
3119 //
3120 // The verification_type_info structure is a u1 tag followed by 0 or
3121 // more bytes of data:
3122 //
3123 // union verification_type_info {
3124 // Top_variable_info;
3125 // Integer_variable_info;
3126 // Float_variable_info;
3127 // Long_variable_info;
3128 // Double_variable_info;
3129 // Null_variable_info;
3130 // UninitializedThis_variable_info;
3131 // Object_variable_info;
3132 // Uninitialized_variable_info;
3133 // }
3134 //
3135 void VM_RedefineClasses::rewrite_cp_refs_in_verification_type_info(
3136 address& stackmap_p_ref, address stackmap_end, u2 frame_i,
3137 u1 frame_type, TRAPS) {
3138
3139 assert(stackmap_p_ref + 1 <= stackmap_end, "no room for tag");
3140 u1 tag = *stackmap_p_ref;
3141 stackmap_p_ref++;
3142
3143 switch (tag) {
3144 // Top_variable_info {
3145 // u1 tag = ITEM_Top; /* 0 */
3146 // }
3147 // verificationType.hpp has zero as ITEM_Bogus instead of ITEM_Top
3148 case 0: // fall through
3149
3150 // Integer_variable_info {
3151 // u1 tag = ITEM_Integer; /* 1 */
3152 // }
3153 case ITEM_Integer: // fall through
3154
3155 // Float_variable_info {
3156 // u1 tag = ITEM_Float; /* 2 */
3157 // }
3158 case ITEM_Float: // fall through
3159
3160 // Double_variable_info {
3161 // u1 tag = ITEM_Double; /* 3 */
3162 // }
3163 case ITEM_Double: // fall through
3164
3165 // Long_variable_info {
3166 // u1 tag = ITEM_Long; /* 4 */
3167 // }
3168 case ITEM_Long: // fall through
3169
3170 // Null_variable_info {
3171 // u1 tag = ITEM_Null; /* 5 */
3172 // }
3173 case ITEM_Null: // fall through
3174
3175 // UninitializedThis_variable_info {
3176 // u1 tag = ITEM_UninitializedThis; /* 6 */
3177 // }
3178 case ITEM_UninitializedThis:
3179 // nothing more to do for the above tag types
3180 break;
3181
3182 // Object_variable_info {
3183 // u1 tag = ITEM_Object; /* 7 */
3184 // u2 cpool_index;
3185 // }
3186 case ITEM_Object:
3187 {
3188 assert(stackmap_p_ref + 2 <= stackmap_end, "no room for cpool_index");
3189 u2 cpool_index = Bytes::get_Java_u2(stackmap_p_ref);
3190 u2 new_cp_index = find_new_index(cpool_index);
3191 if (new_cp_index != 0) {
3192 log_debug(redefine, class, stackmap)("mapped old cpool_index=%d", cpool_index);
3193 Bytes::put_Java_u2(stackmap_p_ref, new_cp_index);
3194 cpool_index = new_cp_index;
3195 }
3196 stackmap_p_ref += 2;
3197
3198 log_debug(redefine, class, stackmap)
3199 ("frame_i=%u, frame_type=%u, cpool_index=%d", frame_i, frame_type, cpool_index);
3200 } break;
3201
3202 // Uninitialized_variable_info {
3203 // u1 tag = ITEM_Uninitialized; /* 8 */
3204 // u2 offset;
3205 // }
3206 case ITEM_Uninitialized:
3207 assert(stackmap_p_ref + 2 <= stackmap_end, "no room for offset");
3208 stackmap_p_ref += 2;
3209 break;
3210
3211 default:
3212 log_debug(redefine, class, stackmap)("frame_i=%u, frame_type=%u, bad tag=0x%x", frame_i, frame_type, tag);
3213 ShouldNotReachHere();
3214 break;
3215 } // end switch (tag)
3216 } // end rewrite_cp_refs_in_verification_type_info()
3217
3218
3219 // Change the constant pool associated with klass scratch_class to
3220 // scratch_cp. If shrink is true, then scratch_cp_length elements
3221 // are copied from scratch_cp to a smaller constant pool and the
3222 // smaller constant pool is associated with scratch_class.
3223 void VM_RedefineClasses::set_new_constant_pool(
3224 ClassLoaderData* loader_data,
3225 InstanceKlass* scratch_class, constantPoolHandle scratch_cp,
3226 int scratch_cp_length, TRAPS) {
3227 assert(scratch_cp->length() >= scratch_cp_length, "sanity check");
3228
3229 // scratch_cp is a merged constant pool and has enough space for a
3230 // worst case merge situation. We want to associate the minimum
3231 // sized constant pool with the klass to save space.
3232 ConstantPool* cp = ConstantPool::allocate(loader_data, scratch_cp_length, CHECK);
3233 constantPoolHandle smaller_cp(THREAD, cp);
3234
3235 // preserve version() value in the smaller copy
3236 int version = scratch_cp->version();
3237 assert(version != 0, "sanity check");
3238 smaller_cp->set_version(version);
3239
3240 // attach klass to new constant pool
3241 // reference to the cp holder is needed for copy_operands()
3242 smaller_cp->set_pool_holder(scratch_class);
3243
3244 scratch_cp->copy_cp_to(1, scratch_cp_length - 1, smaller_cp, 1, THREAD);
3245 if (HAS_PENDING_EXCEPTION) {
3246 // Exception is handled in the caller
3247 loader_data->add_to_deallocate_list(smaller_cp());
3248 return;
3249 }
3250 scratch_cp = smaller_cp;
3251
3252 // attach new constant pool to klass
3253 scratch_class->set_constants(scratch_cp());
3254 scratch_cp->initialize_unresolved_klasses(loader_data, CHECK);
3255
3256 int i; // for portability
3257
3258 // update each field in klass to use new constant pool indices as needed
3259 for (JavaFieldStream fs(scratch_class); !fs.done(); fs.next()) {
3260 jshort cur_index = fs.name_index();
3261 jshort new_index = find_new_index(cur_index);
3262 if (new_index != 0) {
3263 log_trace(redefine, class, constantpool)("field-name_index change: %d to %d", cur_index, new_index);
3264 fs.set_name_index(new_index);
3265 }
3266 cur_index = fs.signature_index();
3267 new_index = find_new_index(cur_index);
3268 if (new_index != 0) {
3269 log_trace(redefine, class, constantpool)("field-signature_index change: %d to %d", cur_index, new_index);
3270 fs.set_signature_index(new_index);
3271 }
3272 cur_index = fs.initval_index();
3273 new_index = find_new_index(cur_index);
3274 if (new_index != 0) {
3275 log_trace(redefine, class, constantpool)("field-initval_index change: %d to %d", cur_index, new_index);
3276 fs.set_initval_index(new_index);
3277 }
3278 cur_index = fs.generic_signature_index();
3279 new_index = find_new_index(cur_index);
3280 if (new_index != 0) {
3281 log_trace(redefine, class, constantpool)("field-generic_signature change: %d to %d", cur_index, new_index);
3282 fs.set_generic_signature_index(new_index);
3283 }
3284 } // end for each field
3285
3286 // Update constant pool indices in the inner classes info to use
3287 // new constant indices as needed. The inner classes info is a
3288 // quadruple:
3289 // (inner_class_info, outer_class_info, inner_name, inner_access_flags)
3290 InnerClassesIterator iter(scratch_class);
3291 for (; !iter.done(); iter.next()) {
3292 int cur_index = iter.inner_class_info_index();
3293 if (cur_index == 0) {
3294 continue; // JVM spec. allows null inner class refs so skip it
3295 }
3296 int new_index = find_new_index(cur_index);
3297 if (new_index != 0) {
3298 log_trace(redefine, class, constantpool)("inner_class_info change: %d to %d", cur_index, new_index);
3299 iter.set_inner_class_info_index(new_index);
3300 }
3301 cur_index = iter.outer_class_info_index();
3302 new_index = find_new_index(cur_index);
3303 if (new_index != 0) {
3304 log_trace(redefine, class, constantpool)("outer_class_info change: %d to %d", cur_index, new_index);
3305 iter.set_outer_class_info_index(new_index);
3306 }
3307 cur_index = iter.inner_name_index();
3308 new_index = find_new_index(cur_index);
3309 if (new_index != 0) {
3310 log_trace(redefine, class, constantpool)("inner_name change: %d to %d", cur_index, new_index);
3311 iter.set_inner_name_index(new_index);
3312 }
3313 } // end for each inner class
3314
3315 // Attach each method in klass to the new constant pool and update
3316 // to use new constant pool indices as needed:
3317 Array<Method*>* methods = scratch_class->methods();
3318 for (i = methods->length() - 1; i >= 0; i--) {
3319 methodHandle method(THREAD, methods->at(i));
3320 method->set_constants(scratch_cp());
3321
3322 int new_index = find_new_index(method->name_index());
3323 if (new_index != 0) {
3324 log_trace(redefine, class, constantpool)
3325 ("method-name_index change: %d to %d", method->name_index(), new_index);
3326 method->set_name_index(new_index);
3327 }
3328 new_index = find_new_index(method->signature_index());
3329 if (new_index != 0) {
3330 log_trace(redefine, class, constantpool)
3331 ("method-signature_index change: %d to %d", method->signature_index(), new_index);
3332 method->set_signature_index(new_index);
3333 }
3334 new_index = find_new_index(method->generic_signature_index());
3335 if (new_index != 0) {
3336 log_trace(redefine, class, constantpool)
3337 ("method-generic_signature_index change: %d to %d", method->generic_signature_index(), new_index);
3338 method->set_generic_signature_index(new_index);
3339 }
3340
3341 // Update constant pool indices in the method's checked exception
3342 // table to use new constant indices as needed.
3343 int cext_length = method->checked_exceptions_length();
3344 if (cext_length > 0) {
3345 CheckedExceptionElement * cext_table =
3346 method->checked_exceptions_start();
3347 for (int j = 0; j < cext_length; j++) {
3348 int cur_index = cext_table[j].class_cp_index;
3349 int new_index = find_new_index(cur_index);
3350 if (new_index != 0) {
3351 log_trace(redefine, class, constantpool)("cext-class_cp_index change: %d to %d", cur_index, new_index);
3352 cext_table[j].class_cp_index = (u2)new_index;
3353 }
3354 } // end for each checked exception table entry
3355 } // end if there are checked exception table entries
3356
3357 // Update each catch type index in the method's exception table
3358 // to use new constant pool indices as needed. The exception table
3359 // holds quadruple entries of the form:
3360 // (beg_bci, end_bci, handler_bci, klass_index)
3361
3362 ExceptionTable ex_table(method());
3363 int ext_length = ex_table.length();
3364
3365 for (int j = 0; j < ext_length; j ++) {
3366 int cur_index = ex_table.catch_type_index(j);
3367 int new_index = find_new_index(cur_index);
3368 if (new_index != 0) {
3369 log_trace(redefine, class, constantpool)("ext-klass_index change: %d to %d", cur_index, new_index);
3370 ex_table.set_catch_type_index(j, new_index);
3371 }
3372 } // end for each exception table entry
3373
3374 // Update constant pool indices in the method's local variable
3375 // table to use new constant indices as needed. The local variable
3376 // table hold sextuple entries of the form:
3377 // (start_pc, length, name_index, descriptor_index, signature_index, slot)
3378 int lvt_length = method->localvariable_table_length();
3379 if (lvt_length > 0) {
3380 LocalVariableTableElement * lv_table =
3381 method->localvariable_table_start();
3382 for (int j = 0; j < lvt_length; j++) {
3383 int cur_index = lv_table[j].name_cp_index;
3384 int new_index = find_new_index(cur_index);
3385 if (new_index != 0) {
3386 log_trace(redefine, class, constantpool)("lvt-name_cp_index change: %d to %d", cur_index, new_index);
3387 lv_table[j].name_cp_index = (u2)new_index;
3388 }
3389 cur_index = lv_table[j].descriptor_cp_index;
3390 new_index = find_new_index(cur_index);
3391 if (new_index != 0) {
3392 log_trace(redefine, class, constantpool)("lvt-descriptor_cp_index change: %d to %d", cur_index, new_index);
3393 lv_table[j].descriptor_cp_index = (u2)new_index;
3394 }
3395 cur_index = lv_table[j].signature_cp_index;
3396 new_index = find_new_index(cur_index);
3397 if (new_index != 0) {
3398 log_trace(redefine, class, constantpool)("lvt-signature_cp_index change: %d to %d", cur_index, new_index);
3399 lv_table[j].signature_cp_index = (u2)new_index;
3400 }
3401 } // end for each local variable table entry
3402 } // end if there are local variable table entries
3403
3404 rewrite_cp_refs_in_stack_map_table(method, THREAD);
3405 } // end for each method
3406 } // end set_new_constant_pool()
3407
3408
3409 // Unevolving classes may point to methods of the_class directly
3410 // from their constant pool caches, itables, and/or vtables. We
3411 // use the ClassLoaderDataGraph::classes_do() facility and this helper
3412 // to fix up these pointers.
3413
3414 // Adjust cpools and vtables closure
3415 void VM_RedefineClasses::AdjustCpoolCacheAndVtable::do_klass(Klass* k) {
3416
3417 // This is a very busy routine. We don't want too much tracing
3418 // printed out.
3419 bool trace_name_printed = false;
3420 InstanceKlass *the_class = InstanceKlass::cast(_the_class);
3421
3422 // If the class being redefined is java.lang.Object, we need to fix all
3423 // array class vtables also
3424 if (k->is_array_klass() && _the_class == SystemDictionary::Object_klass()) {
3425 k->vtable().adjust_method_entries(the_class, &trace_name_printed);
3426
3427 } else if (k->is_instance_klass()) {
3428 HandleMark hm(_thread);
3429 InstanceKlass *ik = InstanceKlass::cast(k);
3430
3431 // HotSpot specific optimization! HotSpot does not currently
3432 // support delegation from the bootstrap class loader to a
3433 // user-defined class loader. This means that if the bootstrap
3434 // class loader is the initiating class loader, then it will also
3435 // be the defining class loader. This also means that classes
3436 // loaded by the bootstrap class loader cannot refer to classes
3437 // loaded by a user-defined class loader. Note: a user-defined
3438 // class loader can delegate to the bootstrap class loader.
3439 //
3440 // If the current class being redefined has a user-defined class
3441 // loader as its defining class loader, then we can skip all
3442 // classes loaded by the bootstrap class loader.
3443 bool is_user_defined = (_the_class->class_loader() != NULL);
3444 if (is_user_defined && ik->class_loader() == NULL) {
3445 return;
3446 }
3447
3448 // Fix the vtable embedded in the_class and subclasses of the_class,
3449 // if one exists. We discard scratch_class and we don't keep an
3450 // InstanceKlass around to hold obsolete methods so we don't have
3451 // any other InstanceKlass embedded vtables to update. The vtable
3452 // holds the Method*s for virtual (but not final) methods.
3453 // Default methods, or concrete methods in interfaces are stored
3454 // in the vtable, so if an interface changes we need to check
3455 // adjust_method_entries() for every InstanceKlass, which will also
3456 // adjust the default method vtable indices.
3457 // We also need to adjust any default method entries that are
3458 // not yet in the vtable, because the vtable setup is in progress.
3459 // This must be done after we adjust the default_methods and
3460 // default_vtable_indices for methods already in the vtable.
3461 // If redefining Unsafe, walk all the vtables looking for entries.
3462 if (ik->vtable_length() > 0 && (_the_class->is_interface()
3463 || _the_class == SystemDictionary::internal_Unsafe_klass()
3464 || ik->is_subtype_of(_the_class))) {
3465 // ik->vtable() creates a wrapper object; rm cleans it up
3466 ResourceMark rm(_thread);
3467
3468 ik->vtable().adjust_method_entries(the_class, &trace_name_printed);
3469 ik->adjust_default_methods(the_class, &trace_name_printed);
3470 }
3471
3472 // If the current class has an itable and we are either redefining an
3473 // interface or if the current class is a subclass of the_class, then
3474 // we potentially have to fix the itable. If we are redefining an
3475 // interface, then we have to call adjust_method_entries() for
3476 // every InstanceKlass that has an itable since there isn't a
3477 // subclass relationship between an interface and an InstanceKlass.
3478 // If redefining Unsafe, walk all the itables looking for entries.
3479 if (ik->itable_length() > 0 && (_the_class->is_interface()
3480 || _the_class == SystemDictionary::internal_Unsafe_klass()
3481 || ik->is_subclass_of(_the_class))) {
3482 ResourceMark rm(_thread);
3483 ik->itable().adjust_method_entries(the_class, &trace_name_printed);
3484 }
3485
3486 // The constant pools in other classes (other_cp) can refer to
3487 // methods in the_class. We have to update method information in
3488 // other_cp's cache. If other_cp has a previous version, then we
3489 // have to repeat the process for each previous version. The
3490 // constant pool cache holds the Method*s for non-virtual
3491 // methods and for virtual, final methods.
3492 //
3493 // Special case: if the current class is the_class, then new_cp
3494 // has already been attached to the_class and old_cp has already
3495 // been added as a previous version. The new_cp doesn't have any
3496 // cached references to old methods so it doesn't need to be
3497 // updated. We can simply start with the previous version(s) in
3498 // that case.
3499 constantPoolHandle other_cp;
3500 ConstantPoolCache* cp_cache;
3501
3502 if (ik != _the_class) {
3503 // this klass' constant pool cache may need adjustment
3504 other_cp = constantPoolHandle(ik->constants());
3505 cp_cache = other_cp->cache();
3506 if (cp_cache != NULL) {
3507 cp_cache->adjust_method_entries(the_class, &trace_name_printed);
3508 }
3509 }
3510
3511 // the previous versions' constant pool caches may need adjustment
3512 for (InstanceKlass* pv_node = ik->previous_versions();
3513 pv_node != NULL;
3514 pv_node = pv_node->previous_versions()) {
3515 cp_cache = pv_node->constants()->cache();
3516 if (cp_cache != NULL) {
3517 cp_cache->adjust_method_entries(pv_node, &trace_name_printed);
3518 }
3519 }
3520 }
3521 }
3522
3523 // Clean method data for this class
3524 void VM_RedefineClasses::MethodDataCleaner::do_klass(Klass* k) {
3525 if (k->is_instance_klass()) {
3526 InstanceKlass *ik = InstanceKlass::cast(k);
3527 // Clean MethodData of this class's methods so they don't refer to
3528 // old methods that are no longer running.
3529 Array<Method*>* methods = ik->methods();
3530 int num_methods = methods->length();
3531 for (int index = 0; index < num_methods; ++index) {
3532 if (methods->at(index)->method_data() != NULL) {
3533 methods->at(index)->method_data()->clean_weak_method_links();
3534 }
3535 }
3536 }
3537 }
3538
3539 void VM_RedefineClasses::update_jmethod_ids() {
3540 for (int j = 0; j < _matching_methods_length; ++j) {
3541 Method* old_method = _matching_old_methods[j];
3542 jmethodID jmid = old_method->find_jmethod_id_or_null();
3543 if (jmid != NULL) {
3544 // There is a jmethodID, change it to point to the new method
3545 methodHandle new_method_h(_matching_new_methods[j]);
3546 Method::change_method_associated_with_jmethod_id(jmid, new_method_h());
3547 assert(Method::resolve_jmethod_id(jmid) == _matching_new_methods[j],
3548 "should be replaced");
3549 }
3550 }
3551 }
3552
3553 int VM_RedefineClasses::check_methods_and_mark_as_obsolete() {
3554 int emcp_method_count = 0;
3555 int obsolete_count = 0;
3556 int old_index = 0;
3557 for (int j = 0; j < _matching_methods_length; ++j, ++old_index) {
3558 Method* old_method = _matching_old_methods[j];
3559 Method* new_method = _matching_new_methods[j];
3560 Method* old_array_method;
3561
3562 // Maintain an old_index into the _old_methods array by skipping
3563 // deleted methods
3564 while ((old_array_method = _old_methods->at(old_index)) != old_method) {
3565 ++old_index;
3566 }
3567
3568 if (MethodComparator::methods_EMCP(old_method, new_method)) {
3569 // The EMCP definition from JSR-163 requires the bytecodes to be
3570 // the same with the exception of constant pool indices which may
3571 // differ. However, the constants referred to by those indices
3572 // must be the same.
3573 //
3574 // We use methods_EMCP() for comparison since constant pool
3575 // merging can remove duplicate constant pool entries that were
3576 // present in the old method and removed from the rewritten new
3577 // method. A faster binary comparison function would consider the
3578 // old and new methods to be different when they are actually
3579 // EMCP.
3580 //
3581 // The old and new methods are EMCP and you would think that we
3582 // could get rid of one of them here and now and save some space.
3583 // However, the concept of EMCP only considers the bytecodes and
3584 // the constant pool entries in the comparison. Other things,
3585 // e.g., the line number table (LNT) or the local variable table
3586 // (LVT) don't count in the comparison. So the new (and EMCP)
3587 // method can have a new LNT that we need so we can't just
3588 // overwrite the new method with the old method.
3589 //
3590 // When this routine is called, we have already attached the new
3591 // methods to the_class so the old methods are effectively
3592 // overwritten. However, if an old method is still executing,
3593 // then the old method cannot be collected until sometime after
3594 // the old method call has returned. So the overwriting of old
3595 // methods by new methods will save us space except for those
3596 // (hopefully few) old methods that are still executing.
3597 //
3598 // A method refers to a ConstMethod* and this presents another
3599 // possible avenue to space savings. The ConstMethod* in the
3600 // new method contains possibly new attributes (LNT, LVT, etc).
3601 // At first glance, it seems possible to save space by replacing
3602 // the ConstMethod* in the old method with the ConstMethod*
3603 // from the new method. The old and new methods would share the
3604 // same ConstMethod* and we would save the space occupied by
3605 // the old ConstMethod*. However, the ConstMethod* contains
3606 // a back reference to the containing method. Sharing the
3607 // ConstMethod* between two methods could lead to confusion in
3608 // the code that uses the back reference. This would lead to
3609 // brittle code that could be broken in non-obvious ways now or
3610 // in the future.
3611 //
3612 // Another possibility is to copy the ConstMethod* from the new
3613 // method to the old method and then overwrite the new method with
3614 // the old method. Since the ConstMethod* contains the bytecodes
3615 // for the method embedded in the oop, this option would change
3616 // the bytecodes out from under any threads executing the old
3617 // method and make the thread's bcp invalid. Since EMCP requires
3618 // that the bytecodes be the same modulo constant pool indices, it
3619 // is straight forward to compute the correct new bcp in the new
3620 // ConstMethod* from the old bcp in the old ConstMethod*. The
3621 // time consuming part would be searching all the frames in all
3622 // of the threads to find all of the calls to the old method.
3623 //
3624 // It looks like we will have to live with the limited savings
3625 // that we get from effectively overwriting the old methods
3626 // when the new methods are attached to the_class.
3627
3628 // Count number of methods that are EMCP. The method will be marked
3629 // old but not obsolete if it is EMCP.
3630 emcp_method_count++;
3631
3632 // An EMCP method is _not_ obsolete. An obsolete method has a
3633 // different jmethodID than the current method. An EMCP method
3634 // has the same jmethodID as the current method. Having the
3635 // same jmethodID for all EMCP versions of a method allows for
3636 // a consistent view of the EMCP methods regardless of which
3637 // EMCP method you happen to have in hand. For example, a
3638 // breakpoint set in one EMCP method will work for all EMCP
3639 // versions of the method including the current one.
3640 } else {
3641 // mark obsolete methods as such
3642 old_method->set_is_obsolete();
3643 obsolete_count++;
3644
3645 // obsolete methods need a unique idnum so they become new entries in
3646 // the jmethodID cache in InstanceKlass
3647 assert(old_method->method_idnum() == new_method->method_idnum(), "must match");
3648 u2 num = InstanceKlass::cast(_the_class)->next_method_idnum();
3649 if (num != ConstMethod::UNSET_IDNUM) {
3650 old_method->set_method_idnum(num);
3651 }
3652
3653 // With tracing we try not to "yack" too much. The position of
3654 // this trace assumes there are fewer obsolete methods than
3655 // EMCP methods.
3656 if (log_is_enabled(Trace, redefine, class, obsolete, mark)) {
3657 ResourceMark rm;
3658 log_trace(redefine, class, obsolete, mark)
3659 ("mark %s(%s) as obsolete", old_method->name()->as_C_string(), old_method->signature()->as_C_string());
3660 }
3661 }
3662 old_method->set_is_old();
3663 }
3664 for (int i = 0; i < _deleted_methods_length; ++i) {
3665 Method* old_method = _deleted_methods[i];
3666
3667 assert(!old_method->has_vtable_index(),
3668 "cannot delete methods with vtable entries");;
3669
3670 // Mark all deleted methods as old, obsolete and deleted
3671 old_method->set_is_deleted();
3672 old_method->set_is_old();
3673 old_method->set_is_obsolete();
3674 ++obsolete_count;
3675 // With tracing we try not to "yack" too much. The position of
3676 // this trace assumes there are fewer obsolete methods than
3677 // EMCP methods.
3678 if (log_is_enabled(Trace, redefine, class, obsolete, mark)) {
3679 ResourceMark rm;
3680 log_trace(redefine, class, obsolete, mark)
3681 ("mark deleted %s(%s) as obsolete", old_method->name()->as_C_string(), old_method->signature()->as_C_string());
3682 }
3683 }
3684 assert((emcp_method_count + obsolete_count) == _old_methods->length(),
3685 "sanity check");
3686 log_trace(redefine, class, obsolete, mark)("EMCP_cnt=%d, obsolete_cnt=%d", emcp_method_count, obsolete_count);
3687 return emcp_method_count;
3688 }
3689
3690 // This internal class transfers the native function registration from old methods
3691 // to new methods. It is designed to handle both the simple case of unchanged
3692 // native methods and the complex cases of native method prefixes being added and/or
3693 // removed.
3694 // It expects only to be used during the VM_RedefineClasses op (a safepoint).
3695 //
3696 // This class is used after the new methods have been installed in "the_class".
3697 //
3698 // So, for example, the following must be handled. Where 'm' is a method and
3699 // a number followed by an underscore is a prefix.
3700 //
3701 // Old Name New Name
3702 // Simple transfer to new method m -> m
3703 // Add prefix m -> 1_m
3704 // Remove prefix 1_m -> m
3705 // Simultaneous add of prefixes m -> 3_2_1_m
3706 // Simultaneous removal of prefixes 3_2_1_m -> m
3707 // Simultaneous add and remove 1_m -> 2_m
3708 // Same, caused by prefix removal only 3_2_1_m -> 3_2_m
3709 //
3710 class TransferNativeFunctionRegistration {
3711 private:
3712 InstanceKlass* the_class;
3713 int prefix_count;
3714 char** prefixes;
3715
3716 // Recursively search the binary tree of possibly prefixed method names.
3717 // Iteration could be used if all agents were well behaved. Full tree walk is
3718 // more resilent to agents not cleaning up intermediate methods.
3719 // Branch at each depth in the binary tree is:
3720 // (1) without the prefix.
3721 // (2) with the prefix.
3722 // where 'prefix' is the prefix at that 'depth' (first prefix, second prefix,...)
3723 Method* search_prefix_name_space(int depth, char* name_str, size_t name_len,
3724 Symbol* signature) {
3725 TempNewSymbol name_symbol = SymbolTable::probe(name_str, (int)name_len);
3726 if (name_symbol != NULL) {
3727 Method* method = the_class->lookup_method(name_symbol, signature);
3728 if (method != NULL) {
3729 // Even if prefixed, intermediate methods must exist.
3730 if (method->is_native()) {
3731 // Wahoo, we found a (possibly prefixed) version of the method, return it.
3732 return method;
3733 }
3734 if (depth < prefix_count) {
3735 // Try applying further prefixes (other than this one).
3736 method = search_prefix_name_space(depth+1, name_str, name_len, signature);
3737 if (method != NULL) {
3738 return method; // found
3739 }
3740
3741 // Try adding this prefix to the method name and see if it matches
3742 // another method name.
3743 char* prefix = prefixes[depth];
3744 size_t prefix_len = strlen(prefix);
3745 size_t trial_len = name_len + prefix_len;
3746 char* trial_name_str = NEW_RESOURCE_ARRAY(char, trial_len + 1);
3747 strcpy(trial_name_str, prefix);
3748 strcat(trial_name_str, name_str);
3749 method = search_prefix_name_space(depth+1, trial_name_str, trial_len,
3750 signature);
3751 if (method != NULL) {
3752 // If found along this branch, it was prefixed, mark as such
3753 method->set_is_prefixed_native();
3754 return method; // found
3755 }
3756 }
3757 }
3758 }
3759 return NULL; // This whole branch bore nothing
3760 }
3761
3762 // Return the method name with old prefixes stripped away.
3763 char* method_name_without_prefixes(Method* method) {
3764 Symbol* name = method->name();
3765 char* name_str = name->as_utf8();
3766
3767 // Old prefixing may be defunct, strip prefixes, if any.
3768 for (int i = prefix_count-1; i >= 0; i--) {
3769 char* prefix = prefixes[i];
3770 size_t prefix_len = strlen(prefix);
3771 if (strncmp(prefix, name_str, prefix_len) == 0) {
3772 name_str += prefix_len;
3773 }
3774 }
3775 return name_str;
3776 }
3777
3778 // Strip any prefixes off the old native method, then try to find a
3779 // (possibly prefixed) new native that matches it.
3780 Method* strip_and_search_for_new_native(Method* method) {
3781 ResourceMark rm;
3782 char* name_str = method_name_without_prefixes(method);
3783 return search_prefix_name_space(0, name_str, strlen(name_str),
3784 method->signature());
3785 }
3786
3787 public:
3788
3789 // Construct a native method transfer processor for this class.
3790 TransferNativeFunctionRegistration(InstanceKlass* _the_class) {
3791 assert(SafepointSynchronize::is_at_safepoint(), "sanity check");
3792
3793 the_class = _the_class;
3794 prefixes = JvmtiExport::get_all_native_method_prefixes(&prefix_count);
3795 }
3796
3797 // Attempt to transfer any of the old or deleted methods that are native
3798 void transfer_registrations(Method** old_methods, int methods_length) {
3799 for (int j = 0; j < methods_length; j++) {
3800 Method* old_method = old_methods[j];
3801
3802 if (old_method->is_native() && old_method->has_native_function()) {
3803 Method* new_method = strip_and_search_for_new_native(old_method);
3804 if (new_method != NULL) {
3805 // Actually set the native function in the new method.
3806 // Redefine does not send events (except CFLH), certainly not this
3807 // behind the scenes re-registration.
3808 new_method->set_native_function(old_method->native_function(),
3809 !Method::native_bind_event_is_interesting);
3810 }
3811 }
3812 }
3813 }
3814 };
3815
3816 // Don't lose the association between a native method and its JNI function.
3817 void VM_RedefineClasses::transfer_old_native_function_registrations(InstanceKlass* the_class) {
3818 TransferNativeFunctionRegistration transfer(the_class);
3819 transfer.transfer_registrations(_deleted_methods, _deleted_methods_length);
3820 transfer.transfer_registrations(_matching_old_methods, _matching_methods_length);
3821 }
3822
3823 // Deoptimize all compiled code that depends on this class.
3824 //
3825 // If the can_redefine_classes capability is obtained in the onload
3826 // phase then the compiler has recorded all dependencies from startup.
3827 // In that case we need only deoptimize and throw away all compiled code
3828 // that depends on the class.
3829 //
3830 // If can_redefine_classes is obtained sometime after the onload
3831 // phase then the dependency information may be incomplete. In that case
3832 // the first call to RedefineClasses causes all compiled code to be
3833 // thrown away. As can_redefine_classes has been obtained then
3834 // all future compilations will record dependencies so second and
3835 // subsequent calls to RedefineClasses need only throw away code
3836 // that depends on the class.
3837 //
3838 void VM_RedefineClasses::flush_dependent_code(InstanceKlass* ik, TRAPS) {
3839 assert_locked_or_safepoint(Compile_lock);
3840
3841 // All dependencies have been recorded from startup or this is a second or
3842 // subsequent use of RedefineClasses
3843 if (JvmtiExport::all_dependencies_are_recorded()) {
3844 CodeCache::flush_evol_dependents_on(ik);
3845 } else {
3846 CodeCache::mark_all_nmethods_for_deoptimization();
3847
3848 ResourceMark rm(THREAD);
3849 DeoptimizationMarker dm;
3850
3851 // Deoptimize all activations depending on marked nmethods
3852 Deoptimization::deoptimize_dependents();
3853
3854 // Make the dependent methods not entrant
3855 CodeCache::make_marked_nmethods_not_entrant();
3856
3857 // From now on we know that the dependency information is complete
3858 JvmtiExport::set_all_dependencies_are_recorded(true);
3859 }
3860 }
3861
3862 void VM_RedefineClasses::compute_added_deleted_matching_methods() {
3863 Method* old_method;
3864 Method* new_method;
3865
3866 _matching_old_methods = NEW_RESOURCE_ARRAY(Method*, _old_methods->length());
3867 _matching_new_methods = NEW_RESOURCE_ARRAY(Method*, _old_methods->length());
3868 _added_methods = NEW_RESOURCE_ARRAY(Method*, _new_methods->length());
3869 _deleted_methods = NEW_RESOURCE_ARRAY(Method*, _old_methods->length());
3870
3871 _matching_methods_length = 0;
3872 _deleted_methods_length = 0;
3873 _added_methods_length = 0;
3874
3875 int nj = 0;
3876 int oj = 0;
3877 while (true) {
3878 if (oj >= _old_methods->length()) {
3879 if (nj >= _new_methods->length()) {
3880 break; // we've looked at everything, done
3881 }
3882 // New method at the end
3883 new_method = _new_methods->at(nj);
3884 _added_methods[_added_methods_length++] = new_method;
3885 ++nj;
3886 } else if (nj >= _new_methods->length()) {
3887 // Old method, at the end, is deleted
3888 old_method = _old_methods->at(oj);
3889 _deleted_methods[_deleted_methods_length++] = old_method;
3890 ++oj;
3891 } else {
3892 old_method = _old_methods->at(oj);
3893 new_method = _new_methods->at(nj);
3894 if (old_method->name() == new_method->name()) {
3895 if (old_method->signature() == new_method->signature()) {
3896 _matching_old_methods[_matching_methods_length ] = old_method;
3897 _matching_new_methods[_matching_methods_length++] = new_method;
3898 ++nj;
3899 ++oj;
3900 } else {
3901 // added overloaded have already been moved to the end,
3902 // so this is a deleted overloaded method
3903 _deleted_methods[_deleted_methods_length++] = old_method;
3904 ++oj;
3905 }
3906 } else { // names don't match
3907 if (old_method->name()->fast_compare(new_method->name()) > 0) {
3908 // new method
3909 _added_methods[_added_methods_length++] = new_method;
3910 ++nj;
3911 } else {
3912 // deleted method
3913 _deleted_methods[_deleted_methods_length++] = old_method;
3914 ++oj;
3915 }
3916 }
3917 }
3918 }
3919 assert(_matching_methods_length + _deleted_methods_length == _old_methods->length(), "sanity");
3920 assert(_matching_methods_length + _added_methods_length == _new_methods->length(), "sanity");
3921 }
3922
3923
3924 void VM_RedefineClasses::swap_annotations(InstanceKlass* the_class,
3925 InstanceKlass* scratch_class) {
3926 // Swap annotation fields values
3927 Annotations* old_annotations = the_class->annotations();
3928 the_class->set_annotations(scratch_class->annotations());
3929 scratch_class->set_annotations(old_annotations);
3930 }
3931
3932
3933 // Install the redefinition of a class:
3934 // - house keeping (flushing breakpoints and caches, deoptimizing
3935 // dependent compiled code)
3936 // - replacing parts in the_class with parts from scratch_class
3937 // - adding a weak reference to track the obsolete but interesting
3938 // parts of the_class
3939 // - adjusting constant pool caches and vtables in other classes
3940 // that refer to methods in the_class. These adjustments use the
3941 // ClassLoaderDataGraph::classes_do() facility which only allows
3942 // a helper method to be specified. The interesting parameters
3943 // that we would like to pass to the helper method are saved in
3944 // static global fields in the VM operation.
3945 void VM_RedefineClasses::redefine_single_class(jclass the_jclass,
3946 InstanceKlass* scratch_class, TRAPS) {
3947
3948 HandleMark hm(THREAD); // make sure handles from this call are freed
3949
3950 if (log_is_enabled(Info, redefine, class, timer)) {
3951 _timer_rsc_phase1.start();
3952 }
3953
3954 InstanceKlass* the_class = get_ik(the_jclass);
3955
3956 // Remove all breakpoints in methods of this class
3957 JvmtiBreakpoints& jvmti_breakpoints = JvmtiCurrentBreakpoints::get_jvmti_breakpoints();
3958 jvmti_breakpoints.clearall_in_class_at_safepoint(the_class);
3959
3960 // Deoptimize all compiled code that depends on this class
3961 flush_dependent_code(the_class, THREAD);
3962
3963 _old_methods = the_class->methods();
3964 _new_methods = scratch_class->methods();
3965 _the_class = the_class;
3966 compute_added_deleted_matching_methods();
3967 update_jmethod_ids();
3968
3969 _any_class_has_resolved_methods = the_class->has_resolved_methods() || _any_class_has_resolved_methods;
3970
3971 // Attach new constant pool to the original klass. The original
3972 // klass still refers to the old constant pool (for now).
3973 scratch_class->constants()->set_pool_holder(the_class);
3974
3975 #if 0
3976 // In theory, with constant pool merging in place we should be able
3977 // to save space by using the new, merged constant pool in place of
3978 // the old constant pool(s). By "pool(s)" I mean the constant pool in
3979 // the klass version we are replacing now and any constant pool(s) in
3980 // previous versions of klass. Nice theory, doesn't work in practice.
3981 // When this code is enabled, even simple programs throw NullPointer
3982 // exceptions. I'm guessing that this is caused by some constant pool
3983 // cache difference between the new, merged constant pool and the
3984 // constant pool that was just being used by the klass. I'm keeping
3985 // this code around to archive the idea, but the code has to remain
3986 // disabled for now.
3987
3988 // Attach each old method to the new constant pool. This can be
3989 // done here since we are past the bytecode verification and
3990 // constant pool optimization phases.
3991 for (int i = _old_methods->length() - 1; i >= 0; i--) {
3992 Method* method = _old_methods->at(i);
3993 method->set_constants(scratch_class->constants());
3994 }
3995
3996 // NOTE: this doesn't work because you can redefine the same class in two
3997 // threads, each getting their own constant pool data appended to the
3998 // original constant pool. In order for the new methods to work when they
3999 // become old methods, they need to keep their updated copy of the constant pool.
4000
4001 {
4002 // walk all previous versions of the klass
4003 InstanceKlass *ik = the_class;
4004 PreviousVersionWalker pvw(ik);
4005 do {
4006 ik = pvw.next_previous_version();
4007 if (ik != NULL) {
4008
4009 // attach previous version of klass to the new constant pool
4010 ik->set_constants(scratch_class->constants());
4011
4012 // Attach each method in the previous version of klass to the
4013 // new constant pool
4014 Array<Method*>* prev_methods = ik->methods();
4015 for (int i = prev_methods->length() - 1; i >= 0; i--) {
4016 Method* method = prev_methods->at(i);
4017 method->set_constants(scratch_class->constants());
4018 }
4019 }
4020 } while (ik != NULL);
4021 }
4022 #endif
4023
4024 // Replace methods and constantpool
4025 the_class->set_methods(_new_methods);
4026 scratch_class->set_methods(_old_methods); // To prevent potential GCing of the old methods,
4027 // and to be able to undo operation easily.
4028
4029 Array<int>* old_ordering = the_class->method_ordering();
4030 the_class->set_method_ordering(scratch_class->method_ordering());
4031 scratch_class->set_method_ordering(old_ordering);
4032
4033 ConstantPool* old_constants = the_class->constants();
4034 the_class->set_constants(scratch_class->constants());
4035 scratch_class->set_constants(old_constants); // See the previous comment.
4036 #if 0
4037 // We are swapping the guts of "the new class" with the guts of "the
4038 // class". Since the old constant pool has just been attached to "the
4039 // new class", it seems logical to set the pool holder in the old
4040 // constant pool also. However, doing this will change the observable
4041 // class hierarchy for any old methods that are still executing. A
4042 // method can query the identity of its "holder" and this query uses
4043 // the method's constant pool link to find the holder. The change in
4044 // holding class from "the class" to "the new class" can confuse
4045 // things.
4046 //
4047 // Setting the old constant pool's holder will also cause
4048 // verification done during vtable initialization below to fail.
4049 // During vtable initialization, the vtable's class is verified to be
4050 // a subtype of the method's holder. The vtable's class is "the
4051 // class" and the method's holder is gotten from the constant pool
4052 // link in the method itself. For "the class"'s directly implemented
4053 // methods, the method holder is "the class" itself (as gotten from
4054 // the new constant pool). The check works fine in this case. The
4055 // check also works fine for methods inherited from super classes.
4056 //
4057 // Miranda methods are a little more complicated. A miranda method is
4058 // provided by an interface when the class implementing the interface
4059 // does not provide its own method. These interfaces are implemented
4060 // internally as an InstanceKlass. These special instanceKlasses
4061 // share the constant pool of the class that "implements" the
4062 // interface. By sharing the constant pool, the method holder of a
4063 // miranda method is the class that "implements" the interface. In a
4064 // non-redefine situation, the subtype check works fine. However, if
4065 // the old constant pool's pool holder is modified, then the check
4066 // fails because there is no class hierarchy relationship between the
4067 // vtable's class and "the new class".
4068
4069 old_constants->set_pool_holder(scratch_class());
4070 #endif
4071
4072 // track number of methods that are EMCP for add_previous_version() call below
4073 int emcp_method_count = check_methods_and_mark_as_obsolete();
4074 transfer_old_native_function_registrations(the_class);
4075
4076 // The class file bytes from before any retransformable agents mucked
4077 // with them was cached on the scratch class, move to the_class.
4078 // Note: we still want to do this if nothing needed caching since it
4079 // should get cleared in the_class too.
4080 if (the_class->get_cached_class_file() == 0) {
4081 // the_class doesn't have a cache yet so copy it
4082 the_class->set_cached_class_file(scratch_class->get_cached_class_file());
4083 }
4084 else if (scratch_class->get_cached_class_file() !=
4085 the_class->get_cached_class_file()) {
4086 // The same class can be present twice in the scratch classes list or there
4087 // are multiple concurrent RetransformClasses calls on different threads.
4088 // In such cases we have to deallocate scratch_class cached_class_file.
4089 os::free(scratch_class->get_cached_class_file());
4090 }
4091
4092 // NULL out in scratch class to not delete twice. The class to be redefined
4093 // always owns these bytes.
4094 scratch_class->set_cached_class_file(NULL);
4095
4096 // Replace inner_classes
4097 Array<u2>* old_inner_classes = the_class->inner_classes();
4098 the_class->set_inner_classes(scratch_class->inner_classes());
4099 scratch_class->set_inner_classes(old_inner_classes);
4100
4101 // Initialize the vtable and interface table after
4102 // methods have been rewritten
4103 // no exception should happen here since we explicitly
4104 // do not check loader constraints.
4105 // compare_and_normalize_class_versions has already checked:
4106 // - classloaders unchanged, signatures unchanged
4107 // - all instanceKlasses for redefined classes reused & contents updated
4108 the_class->vtable().initialize_vtable(false, THREAD);
4109 the_class->itable().initialize_itable(false, THREAD);
4110 assert(!HAS_PENDING_EXCEPTION || (THREAD->pending_exception()->is_a(SystemDictionary::ThreadDeath_klass())), "redefine exception");
4111
4112 // Leave arrays of jmethodIDs and itable index cache unchanged
4113
4114 // Copy the "source file name" attribute from new class version
4115 the_class->set_source_file_name_index(
4116 scratch_class->source_file_name_index());
4117
4118 // Copy the "source debug extension" attribute from new class version
4119 the_class->set_source_debug_extension(
4120 scratch_class->source_debug_extension(),
4121 scratch_class->source_debug_extension() == NULL ? 0 :
4122 (int)strlen(scratch_class->source_debug_extension()));
4123
4124 // Use of javac -g could be different in the old and the new
4125 if (scratch_class->access_flags().has_localvariable_table() !=
4126 the_class->access_flags().has_localvariable_table()) {
4127
4128 AccessFlags flags = the_class->access_flags();
4129 if (scratch_class->access_flags().has_localvariable_table()) {
4130 flags.set_has_localvariable_table();
4131 } else {
4132 flags.clear_has_localvariable_table();
4133 }
4134 the_class->set_access_flags(flags);
4135 }
4136
4137 swap_annotations(the_class, scratch_class);
4138
4139 // Replace minor version number of class file
4140 u2 old_minor_version = the_class->minor_version();
4141 the_class->set_minor_version(scratch_class->minor_version());
4142 scratch_class->set_minor_version(old_minor_version);
4143
4144 // Replace major version number of class file
4145 u2 old_major_version = the_class->major_version();
4146 the_class->set_major_version(scratch_class->major_version());
4147 scratch_class->set_major_version(old_major_version);
4148
4149 // Replace CP indexes for class and name+type of enclosing method
4150 u2 old_class_idx = the_class->enclosing_method_class_index();
4151 u2 old_method_idx = the_class->enclosing_method_method_index();
4152 the_class->set_enclosing_method_indices(
4153 scratch_class->enclosing_method_class_index(),
4154 scratch_class->enclosing_method_method_index());
4155 scratch_class->set_enclosing_method_indices(old_class_idx, old_method_idx);
4156
4157 // Replace fingerprint data
4158 the_class->set_has_passed_fingerprint_check(scratch_class->has_passed_fingerprint_check());
4159 the_class->store_fingerprint(scratch_class->get_stored_fingerprint());
4160
4161 the_class->set_has_been_redefined();
4162
4163 if (!the_class->should_be_initialized()) {
4164 // Class was already initialized, so AOT has only seen the original version.
4165 // We need to let AOT look at it again.
4166 AOTLoader::load_for_klass(the_class, THREAD);
4167 }
4168
4169 // keep track of previous versions of this class
4170 the_class->add_previous_version(scratch_class, emcp_method_count);
4171
4172 _timer_rsc_phase1.stop();
4173 if (log_is_enabled(Info, redefine, class, timer)) {
4174 _timer_rsc_phase2.start();
4175 }
4176
4177 // Adjust constantpool caches and vtables for all classes
4178 // that reference methods of the evolved class.
4179 AdjustCpoolCacheAndVtable adjust_cpool_cache_and_vtable(THREAD);
4180 ClassLoaderDataGraph::classes_do(&adjust_cpool_cache_and_vtable);
4181
4182 if (the_class->oop_map_cache() != NULL) {
4183 // Flush references to any obsolete methods from the oop map cache
4184 // so that obsolete methods are not pinned.
4185 the_class->oop_map_cache()->flush_obsolete_entries();
4186 }
4187
4188 increment_class_counter((InstanceKlass *)the_class, THREAD);
4189 {
4190 ResourceMark rm(THREAD);
4191 // increment the classRedefinedCount field in the_class and in any
4192 // direct and indirect subclasses of the_class
4193 log_info(redefine, class, load)
4194 ("redefined name=%s, count=%d (avail_mem=" UINT64_FORMAT "K)",
4195 the_class->external_name(), java_lang_Class::classRedefinedCount(the_class->java_mirror()), os::available_memory() >> 10);
4196 Events::log_redefinition(THREAD, "redefined class name=%s, count=%d",
4197 the_class->external_name(),
4198 java_lang_Class::classRedefinedCount(the_class->java_mirror()));
4199
4200 }
4201 _timer_rsc_phase2.stop();
4202 } // end redefine_single_class()
4203
4204
4205 // Increment the classRedefinedCount field in the specific InstanceKlass
4206 // and in all direct and indirect subclasses.
4207 void VM_RedefineClasses::increment_class_counter(InstanceKlass *ik, TRAPS) {
4208 oop class_mirror = ik->java_mirror();
4209 Klass* class_oop = java_lang_Class::as_Klass(class_mirror);
4210 int new_count = java_lang_Class::classRedefinedCount(class_mirror) + 1;
4211 java_lang_Class::set_classRedefinedCount(class_mirror, new_count);
4212
4213 if (class_oop != _the_class) {
4214 // _the_class count is printed at end of redefine_single_class()
4215 log_debug(redefine, class, subclass)("updated count in subclass=%s to %d", ik->external_name(), new_count);
4216 }
4217
4218 for (Klass *subk = ik->subklass(); subk != NULL;
4219 subk = subk->next_sibling()) {
4220 if (subk->is_instance_klass()) {
4221 // Only update instanceKlasses
4222 InstanceKlass *subik = InstanceKlass::cast(subk);
4223 // recursively do subclasses of the current subclass
4224 increment_class_counter(subik, THREAD);
4225 }
4226 }
4227 }
4228
4229 void VM_RedefineClasses::CheckClass::do_klass(Klass* k) {
4230 bool no_old_methods = true; // be optimistic
4231
4232 // Both array and instance classes have vtables.
4233 // a vtable should never contain old or obsolete methods
4234 ResourceMark rm(_thread);
4235 if (k->vtable_length() > 0 &&
4236 !k->vtable().check_no_old_or_obsolete_entries()) {
4237 if (log_is_enabled(Trace, redefine, class, obsolete, metadata)) {
4238 log_trace(redefine, class, obsolete, metadata)
4239 ("klassVtable::check_no_old_or_obsolete_entries failure -- OLD or OBSOLETE method found -- class: %s",
4240 k->signature_name());
4241 k->vtable().dump_vtable();
4242 }
4243 no_old_methods = false;
4244 }
4245
4246 if (k->is_instance_klass()) {
4247 HandleMark hm(_thread);
4248 InstanceKlass *ik = InstanceKlass::cast(k);
4249
4250 // an itable should never contain old or obsolete methods
4251 if (ik->itable_length() > 0 &&
4252 !ik->itable().check_no_old_or_obsolete_entries()) {
4253 if (log_is_enabled(Trace, redefine, class, obsolete, metadata)) {
4254 log_trace(redefine, class, obsolete, metadata)
4255 ("klassItable::check_no_old_or_obsolete_entries failure -- OLD or OBSOLETE method found -- class: %s",
4256 ik->signature_name());
4257 ik->itable().dump_itable();
4258 }
4259 no_old_methods = false;
4260 }
4261
4262 // the constant pool cache should never contain non-deleted old or obsolete methods
4263 if (ik->constants() != NULL &&
4264 ik->constants()->cache() != NULL &&
4265 !ik->constants()->cache()->check_no_old_or_obsolete_entries()) {
4266 if (log_is_enabled(Trace, redefine, class, obsolete, metadata)) {
4267 log_trace(redefine, class, obsolete, metadata)
4268 ("cp-cache::check_no_old_or_obsolete_entries failure -- OLD or OBSOLETE method found -- class: %s",
4269 ik->signature_name());
4270 ik->constants()->cache()->dump_cache();
4271 }
4272 no_old_methods = false;
4273 }
4274 }
4275
4276 // print and fail guarantee if old methods are found.
4277 if (!no_old_methods) {
4278 if (log_is_enabled(Trace, redefine, class, obsolete, metadata)) {
4279 dump_methods();
4280 } else {
4281 log_trace(redefine, class)("Use the '-Xlog:redefine+class*:' option "
4282 "to see more info about the following guarantee() failure.");
4283 }
4284 guarantee(false, "OLD and/or OBSOLETE method(s) found");
4285 }
4286 }
4287
4288
4289 void VM_RedefineClasses::dump_methods() {
4290 int j;
4291 log_trace(redefine, class, dump)("_old_methods --");
4292 for (j = 0; j < _old_methods->length(); ++j) {
4293 LogStreamHandle(Trace, redefine, class, dump) log_stream;
4294 Method* m = _old_methods->at(j);
4295 log_stream.print("%4d (%5d) ", j, m->vtable_index());
4296 m->access_flags().print_on(&log_stream);
4297 log_stream.print(" -- ");
4298 m->print_name(&log_stream);
4299 log_stream.cr();
4300 }
4301 log_trace(redefine, class, dump)("_new_methods --");
4302 for (j = 0; j < _new_methods->length(); ++j) {
4303 LogStreamHandle(Trace, redefine, class, dump) log_stream;
4304 Method* m = _new_methods->at(j);
4305 log_stream.print("%4d (%5d) ", j, m->vtable_index());
4306 m->access_flags().print_on(&log_stream);
4307 log_stream.print(" -- ");
4308 m->print_name(&log_stream);
4309 log_stream.cr();
4310 }
4311 log_trace(redefine, class, dump)("_matching_methods --");
4312 for (j = 0; j < _matching_methods_length; ++j) {
4313 LogStreamHandle(Trace, redefine, class, dump) log_stream;
4314 Method* m = _matching_old_methods[j];
4315 log_stream.print("%4d (%5d) ", j, m->vtable_index());
4316 m->access_flags().print_on(&log_stream);
4317 log_stream.print(" -- ");
4318 m->print_name();
4319 log_stream.cr();
4320
4321 m = _matching_new_methods[j];
4322 log_stream.print(" (%5d) ", m->vtable_index());
4323 m->access_flags().print_on(&log_stream);
4324 log_stream.cr();
4325 }
4326 log_trace(redefine, class, dump)("_deleted_methods --");
4327 for (j = 0; j < _deleted_methods_length; ++j) {
4328 LogStreamHandle(Trace, redefine, class, dump) log_stream;
4329 Method* m = _deleted_methods[j];
4330 log_stream.print("%4d (%5d) ", j, m->vtable_index());
4331 m->access_flags().print_on(&log_stream);
4332 log_stream.print(" -- ");
4333 m->print_name(&log_stream);
4334 log_stream.cr();
4335 }
4336 log_trace(redefine, class, dump)("_added_methods --");
4337 for (j = 0; j < _added_methods_length; ++j) {
4338 LogStreamHandle(Trace, redefine, class, dump) log_stream;
4339 Method* m = _added_methods[j];
4340 log_stream.print("%4d (%5d) ", j, m->vtable_index());
4341 m->access_flags().print_on(&log_stream);
4342 log_stream.print(" -- ");
4343 m->print_name(&log_stream);
4344 log_stream.cr();
4345 }
4346 }
4347
4348 void VM_RedefineClasses::print_on_error(outputStream* st) const {
4349 VM_Operation::print_on_error(st);
4350 if (_the_class != NULL) {
4351 ResourceMark rm;
4352 st->print_cr(", redefining class %s", _the_class->external_name());
4353 }
4354 }