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 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
242 void VM_RedefineClasses::doit_epilogue() {
243 unlock_classes();
244
245 // Free os::malloc allocated memory.
246 os::free(_scratch_classes);
247
248 // Reset the_class to null for error printing.
249 _the_class = NULL;
250
251 if (log_is_enabled(Info, redefine, class, timer)) {
252 // Used to have separate timers for "doit" and "all", but the timer
253 // overhead skewed the measurements.
254 julong doit_time = _timer_rsc_phase1.milliseconds() +
255 _timer_rsc_phase2.milliseconds();
256 julong all_time = _timer_vm_op_prologue.milliseconds() + doit_time;
257
258 log_info(redefine, class, timer)
259 ("vm_op: all=" JULONG_FORMAT " prologue=" JULONG_FORMAT " doit=" JULONG_FORMAT,
260 all_time, (julong)_timer_vm_op_prologue.milliseconds(), doit_time);
261 log_info(redefine, class, timer)
262 ("redefine_single_class: phase1=" JULONG_FORMAT " phase2=" JULONG_FORMAT,
263 (julong)_timer_rsc_phase1.milliseconds(), (julong)_timer_rsc_phase2.milliseconds());
264 }
265 }
266
267 bool VM_RedefineClasses::is_modifiable_class(oop klass_mirror) {
268 // classes for primitives cannot be redefined
269 if (java_lang_Class::is_primitive(klass_mirror)) {
270 return false;
271 }
272 Klass* k = java_lang_Class::as_Klass(klass_mirror);
273 // classes for arrays cannot be redefined
274 if (k == NULL || !k->is_instance_klass()) {
275 return false;
276 }
277
278 // Cannot redefine or retransform an anonymous class.
279 if (InstanceKlass::cast(k)->is_anonymous()) {
280 return false;
281 }
282 return true;
283 }
284
285 // Append the current entry at scratch_i in scratch_cp to *merge_cp_p
286 // where the end of *merge_cp_p is specified by *merge_cp_length_p. For
287 // direct CP entries, there is just the current entry to append. For
288 // indirect and double-indirect CP entries, there are zero or more
289 // referenced CP entries along with the current entry to append.
290 // Indirect and double-indirect CP entries are handled by recursive
291 // calls to append_entry() as needed. The referenced CP entries are
292 // always appended to *merge_cp_p before the referee CP entry. These
293 // referenced CP entries may already exist in *merge_cp_p in which case
294 // there is nothing extra to append and only the current entry is
295 // appended.
296 void VM_RedefineClasses::append_entry(const constantPoolHandle& scratch_cp,
297 int scratch_i, constantPoolHandle *merge_cp_p, int *merge_cp_length_p,
298 TRAPS) {
299
300 // append is different depending on entry tag type
301 switch (scratch_cp->tag_at(scratch_i).value()) {
302
303 // The old verifier is implemented outside the VM. It loads classes,
304 // but does not resolve constant pool entries directly so we never
305 // see Class entries here with the old verifier. Similarly the old
306 // verifier does not like Class entries in the input constant pool.
307 // The split-verifier is implemented in the VM so it can optionally
308 // and directly resolve constant pool entries to load classes. The
309 // split-verifier can accept either Class entries or UnresolvedClass
310 // entries in the input constant pool. We revert the appended copy
311 // back to UnresolvedClass so that either verifier will be happy
312 // with the constant pool entry.
313 //
314 // this is an indirect CP entry so it needs special handling
315 case JVM_CONSTANT_Class:
316 case JVM_CONSTANT_UnresolvedClass:
317 {
318 int name_i = scratch_cp->klass_name_index_at(scratch_i);
319 int new_name_i = find_or_append_indirect_entry(scratch_cp, name_i, merge_cp_p,
320 merge_cp_length_p, THREAD);
321
322 if (new_name_i != name_i) {
323 log_trace(redefine, class, constantpool)
324 ("Class entry@%d name_index change: %d to %d",
325 *merge_cp_length_p, name_i, new_name_i);
326 }
327
328 (*merge_cp_p)->temp_unresolved_klass_at_put(*merge_cp_length_p, new_name_i);
329 if (scratch_i != *merge_cp_length_p) {
330 // The new entry in *merge_cp_p is at a different index than
331 // the new entry in scratch_cp so we need to map the index values.
332 map_index(scratch_cp, scratch_i, *merge_cp_length_p);
333 }
334 (*merge_cp_length_p)++;
335 } break;
336
337 // these are direct CP entries so they can be directly appended,
338 // but double and long take two constant pool entries
339 case JVM_CONSTANT_Double: // fall through
340 case JVM_CONSTANT_Long:
341 {
342 ConstantPool::copy_entry_to(scratch_cp, scratch_i, *merge_cp_p, *merge_cp_length_p,
343 THREAD);
344
345 if (scratch_i != *merge_cp_length_p) {
346 // The new entry in *merge_cp_p is at a different index than
347 // the new entry in scratch_cp so we need to map the index values.
348 map_index(scratch_cp, scratch_i, *merge_cp_length_p);
349 }
350 (*merge_cp_length_p) += 2;
351 } break;
352
353 // these are direct CP entries so they can be directly appended
354 case JVM_CONSTANT_Float: // fall through
355 case JVM_CONSTANT_Integer: // fall through
356 case JVM_CONSTANT_Utf8: // fall through
357
358 // This was an indirect CP entry, but it has been changed into
359 // Symbol*s so this entry can be directly appended.
360 case JVM_CONSTANT_String: // fall through
361 {
362 ConstantPool::copy_entry_to(scratch_cp, scratch_i, *merge_cp_p, *merge_cp_length_p,
363 THREAD);
364
365 if (scratch_i != *merge_cp_length_p) {
366 // The new entry in *merge_cp_p is at a different index than
367 // the new entry in scratch_cp so we need to map the index values.
368 map_index(scratch_cp, scratch_i, *merge_cp_length_p);
369 }
370 (*merge_cp_length_p)++;
371 } break;
372
373 // this is an indirect CP entry so it needs special handling
374 case JVM_CONSTANT_NameAndType:
375 {
376 int name_ref_i = scratch_cp->name_ref_index_at(scratch_i);
377 int new_name_ref_i = find_or_append_indirect_entry(scratch_cp, name_ref_i, merge_cp_p,
378 merge_cp_length_p, THREAD);
379
380 int signature_ref_i = scratch_cp->signature_ref_index_at(scratch_i);
381 int new_signature_ref_i = find_or_append_indirect_entry(scratch_cp, signature_ref_i,
382 merge_cp_p, merge_cp_length_p,
383 THREAD);
384
385 // If the referenced entries already exist in *merge_cp_p, then
386 // both new_name_ref_i and new_signature_ref_i will both be 0.
387 // In that case, all we are appending is the current entry.
388 if (new_name_ref_i != name_ref_i) {
389 log_trace(redefine, class, constantpool)
390 ("NameAndType entry@%d name_ref_index change: %d to %d",
391 *merge_cp_length_p, name_ref_i, new_name_ref_i);
392 }
393 if (new_signature_ref_i != signature_ref_i) {
394 log_trace(redefine, class, constantpool)
395 ("NameAndType entry@%d signature_ref_index change: %d to %d",
396 *merge_cp_length_p, signature_ref_i, new_signature_ref_i);
397 }
398
399 (*merge_cp_p)->name_and_type_at_put(*merge_cp_length_p,
400 new_name_ref_i, new_signature_ref_i);
401 if (scratch_i != *merge_cp_length_p) {
402 // The new entry in *merge_cp_p is at a different index than
403 // the new entry in scratch_cp so we need to map the index values.
404 map_index(scratch_cp, scratch_i, *merge_cp_length_p);
405 }
406 (*merge_cp_length_p)++;
407 } break;
408
409 // this is a double-indirect CP entry so it needs special handling
410 case JVM_CONSTANT_Fieldref: // fall through
411 case JVM_CONSTANT_InterfaceMethodref: // fall through
412 case JVM_CONSTANT_Methodref:
413 {
414 int klass_ref_i = scratch_cp->uncached_klass_ref_index_at(scratch_i);
415 int new_klass_ref_i = find_or_append_indirect_entry(scratch_cp, klass_ref_i,
416 merge_cp_p, merge_cp_length_p, THREAD);
417
418 int name_and_type_ref_i = scratch_cp->uncached_name_and_type_ref_index_at(scratch_i);
419 int new_name_and_type_ref_i = find_or_append_indirect_entry(scratch_cp, name_and_type_ref_i,
420 merge_cp_p, merge_cp_length_p, THREAD);
421
422 const char *entry_name = NULL;
423 switch (scratch_cp->tag_at(scratch_i).value()) {
424 case JVM_CONSTANT_Fieldref:
425 entry_name = "Fieldref";
426 (*merge_cp_p)->field_at_put(*merge_cp_length_p, new_klass_ref_i,
427 new_name_and_type_ref_i);
428 break;
429 case JVM_CONSTANT_InterfaceMethodref:
430 entry_name = "IFMethodref";
431 (*merge_cp_p)->interface_method_at_put(*merge_cp_length_p,
432 new_klass_ref_i, new_name_and_type_ref_i);
433 break;
434 case JVM_CONSTANT_Methodref:
435 entry_name = "Methodref";
436 (*merge_cp_p)->method_at_put(*merge_cp_length_p, new_klass_ref_i,
437 new_name_and_type_ref_i);
438 break;
439 default:
440 guarantee(false, "bad switch");
441 break;
442 }
443
444 if (klass_ref_i != new_klass_ref_i) {
445 log_trace(redefine, class, constantpool)
446 ("%s entry@%d class_index changed: %d to %d", entry_name, *merge_cp_length_p, klass_ref_i, new_klass_ref_i);
447 }
448 if (name_and_type_ref_i != new_name_and_type_ref_i) {
449 log_trace(redefine, class, constantpool)
450 ("%s entry@%d name_and_type_index changed: %d to %d",
451 entry_name, *merge_cp_length_p, name_and_type_ref_i, new_name_and_type_ref_i);
452 }
453
454 if (scratch_i != *merge_cp_length_p) {
455 // The new entry in *merge_cp_p is at a different index than
456 // the new entry in scratch_cp so we need to map the index values.
457 map_index(scratch_cp, scratch_i, *merge_cp_length_p);
458 }
459 (*merge_cp_length_p)++;
460 } break;
461
462 // this is an indirect CP entry so it needs special handling
463 case JVM_CONSTANT_MethodType:
464 {
465 int ref_i = scratch_cp->method_type_index_at(scratch_i);
466 int new_ref_i = find_or_append_indirect_entry(scratch_cp, ref_i, merge_cp_p,
467 merge_cp_length_p, THREAD);
468 if (new_ref_i != ref_i) {
469 log_trace(redefine, class, constantpool)
470 ("MethodType entry@%d ref_index change: %d to %d", *merge_cp_length_p, ref_i, new_ref_i);
471 }
472 (*merge_cp_p)->method_type_index_at_put(*merge_cp_length_p, new_ref_i);
473 if (scratch_i != *merge_cp_length_p) {
474 // The new entry in *merge_cp_p is at a different index than
475 // the new entry in scratch_cp so we need to map the index values.
476 map_index(scratch_cp, scratch_i, *merge_cp_length_p);
477 }
478 (*merge_cp_length_p)++;
479 } break;
480
481 // this is an indirect CP entry so it needs special handling
482 case JVM_CONSTANT_MethodHandle:
483 {
484 int ref_kind = scratch_cp->method_handle_ref_kind_at(scratch_i);
485 int ref_i = scratch_cp->method_handle_index_at(scratch_i);
486 int new_ref_i = find_or_append_indirect_entry(scratch_cp, ref_i, merge_cp_p,
487 merge_cp_length_p, THREAD);
488 if (new_ref_i != ref_i) {
489 log_trace(redefine, class, constantpool)
490 ("MethodHandle entry@%d ref_index change: %d to %d", *merge_cp_length_p, ref_i, new_ref_i);
491 }
492 (*merge_cp_p)->method_handle_index_at_put(*merge_cp_length_p, ref_kind, new_ref_i);
493 if (scratch_i != *merge_cp_length_p) {
494 // The new entry in *merge_cp_p is at a different index than
495 // the new entry in scratch_cp so we need to map the index values.
496 map_index(scratch_cp, scratch_i, *merge_cp_length_p);
497 }
498 (*merge_cp_length_p)++;
499 } break;
500
501 // this is an indirect CP entry so it needs special handling
502 case JVM_CONSTANT_Dynamic: // fall through
503 case JVM_CONSTANT_InvokeDynamic:
504 {
505 // Index of the bootstrap specifier in the operands array
506 int old_bs_i = scratch_cp->invoke_dynamic_bootstrap_specifier_index(scratch_i);
507 int new_bs_i = find_or_append_operand(scratch_cp, old_bs_i, merge_cp_p,
508 merge_cp_length_p, THREAD);
509 // The bootstrap method NameAndType_info index
510 int old_ref_i = scratch_cp->invoke_dynamic_name_and_type_ref_index_at(scratch_i);
511 int new_ref_i = find_or_append_indirect_entry(scratch_cp, old_ref_i, merge_cp_p,
512 merge_cp_length_p, THREAD);
513 if (new_bs_i != old_bs_i) {
514 log_trace(redefine, class, constantpool)
515 ("Dynamic entry@%d bootstrap_method_attr_index change: %d to %d",
516 *merge_cp_length_p, old_bs_i, new_bs_i);
517 }
518 if (new_ref_i != old_ref_i) {
519 log_trace(redefine, class, constantpool)
520 ("Dynamic entry@%d name_and_type_index change: %d to %d", *merge_cp_length_p, old_ref_i, new_ref_i);
521 }
522
523 if (scratch_cp->tag_at(scratch_i).is_dynamic_constant())
524 (*merge_cp_p)->dynamic_constant_at_put(*merge_cp_length_p, new_bs_i, new_ref_i);
525 else
526 (*merge_cp_p)->invoke_dynamic_at_put(*merge_cp_length_p, new_bs_i, new_ref_i);
527 if (scratch_i != *merge_cp_length_p) {
528 // The new entry in *merge_cp_p is at a different index than
529 // the new entry in scratch_cp so we need to map the index values.
530 map_index(scratch_cp, scratch_i, *merge_cp_length_p);
531 }
532 (*merge_cp_length_p)++;
533 } break;
534
535 // At this stage, Class or UnresolvedClass could be in scratch_cp, but not
536 // ClassIndex
537 case JVM_CONSTANT_ClassIndex: // fall through
538
539 // Invalid is used as the tag for the second constant pool entry
540 // occupied by JVM_CONSTANT_Double or JVM_CONSTANT_Long. It should
541 // not be seen by itself.
542 case JVM_CONSTANT_Invalid: // fall through
543
544 // At this stage, String could be here, but not StringIndex
545 case JVM_CONSTANT_StringIndex: // fall through
546
547 // At this stage JVM_CONSTANT_UnresolvedClassInError should not be
548 // here
549 case JVM_CONSTANT_UnresolvedClassInError: // fall through
550
551 default:
552 {
553 // leave a breadcrumb
554 jbyte bad_value = scratch_cp->tag_at(scratch_i).value();
555 ShouldNotReachHere();
556 } break;
557 } // end switch tag value
558 } // end append_entry()
559
560
561 int VM_RedefineClasses::find_or_append_indirect_entry(const constantPoolHandle& scratch_cp,
562 int ref_i, constantPoolHandle *merge_cp_p, int *merge_cp_length_p, TRAPS) {
563
564 int new_ref_i = ref_i;
565 bool match = (ref_i < *merge_cp_length_p) &&
566 scratch_cp->compare_entry_to(ref_i, *merge_cp_p, ref_i, THREAD);
567
568 if (!match) {
569 // forward reference in *merge_cp_p or not a direct match
570 int found_i = scratch_cp->find_matching_entry(ref_i, *merge_cp_p, THREAD);
571 if (found_i != 0) {
572 guarantee(found_i != ref_i, "compare_entry_to() and find_matching_entry() do not agree");
573 // Found a matching entry somewhere else in *merge_cp_p so just need a mapping entry.
574 new_ref_i = found_i;
575 map_index(scratch_cp, ref_i, found_i);
576 } else {
577 // no match found so we have to append this entry to *merge_cp_p
578 append_entry(scratch_cp, ref_i, merge_cp_p, merge_cp_length_p, THREAD);
579 // The above call to append_entry() can only append one entry
580 // so the post call query of *merge_cp_length_p is only for
581 // the sake of consistency.
582 new_ref_i = *merge_cp_length_p - 1;
583 }
584 }
585
586 return new_ref_i;
587 } // end find_or_append_indirect_entry()
588
589
590 // Append a bootstrap specifier into the merge_cp operands that is semantically equal
591 // to the scratch_cp operands bootstrap specifier passed by the old_bs_i index.
592 // Recursively append new merge_cp entries referenced by the new bootstrap specifier.
593 void VM_RedefineClasses::append_operand(const constantPoolHandle& scratch_cp, int old_bs_i,
594 constantPoolHandle *merge_cp_p, int *merge_cp_length_p, TRAPS) {
595
596 int old_ref_i = scratch_cp->operand_bootstrap_method_ref_index_at(old_bs_i);
597 int new_ref_i = find_or_append_indirect_entry(scratch_cp, old_ref_i, merge_cp_p,
598 merge_cp_length_p, THREAD);
599 if (new_ref_i != old_ref_i) {
600 log_trace(redefine, class, constantpool)
601 ("operands entry@%d bootstrap method ref_index change: %d to %d", _operands_cur_length, old_ref_i, new_ref_i);
602 }
603
604 Array<u2>* merge_ops = (*merge_cp_p)->operands();
605 int new_bs_i = _operands_cur_length;
606 // We have _operands_cur_length == 0 when the merge_cp operands is empty yet.
607 // However, the operand_offset_at(0) was set in the extend_operands() call.
608 int new_base = (new_bs_i == 0) ? (*merge_cp_p)->operand_offset_at(0)
609 : (*merge_cp_p)->operand_next_offset_at(new_bs_i - 1);
610 int argc = scratch_cp->operand_argument_count_at(old_bs_i);
611
612 ConstantPool::operand_offset_at_put(merge_ops, _operands_cur_length, new_base);
613 merge_ops->at_put(new_base++, new_ref_i);
614 merge_ops->at_put(new_base++, argc);
615
616 for (int i = 0; i < argc; i++) {
617 int old_arg_ref_i = scratch_cp->operand_argument_index_at(old_bs_i, i);
618 int new_arg_ref_i = find_or_append_indirect_entry(scratch_cp, old_arg_ref_i, merge_cp_p,
619 merge_cp_length_p, THREAD);
620 merge_ops->at_put(new_base++, new_arg_ref_i);
621 if (new_arg_ref_i != old_arg_ref_i) {
622 log_trace(redefine, class, constantpool)
623 ("operands entry@%d bootstrap method argument ref_index change: %d to %d",
624 _operands_cur_length, old_arg_ref_i, new_arg_ref_i);
625 }
626 }
627 if (old_bs_i != _operands_cur_length) {
628 // The bootstrap specifier in *merge_cp_p is at a different index than
629 // that in scratch_cp so we need to map the index values.
630 map_operand_index(old_bs_i, new_bs_i);
631 }
632 _operands_cur_length++;
633 } // end append_operand()
634
635
636 int VM_RedefineClasses::find_or_append_operand(const constantPoolHandle& scratch_cp,
637 int old_bs_i, constantPoolHandle *merge_cp_p, int *merge_cp_length_p, TRAPS) {
638
639 int new_bs_i = old_bs_i; // bootstrap specifier index
640 bool match = (old_bs_i < _operands_cur_length) &&
641 scratch_cp->compare_operand_to(old_bs_i, *merge_cp_p, old_bs_i, THREAD);
642
643 if (!match) {
644 // forward reference in *merge_cp_p or not a direct match
645 int found_i = scratch_cp->find_matching_operand(old_bs_i, *merge_cp_p,
646 _operands_cur_length, THREAD);
647 if (found_i != -1) {
648 guarantee(found_i != old_bs_i, "compare_operand_to() and find_matching_operand() disagree");
649 // found a matching operand somewhere else in *merge_cp_p so just need a mapping
650 new_bs_i = found_i;
651 map_operand_index(old_bs_i, found_i);
652 } else {
653 // no match found so we have to append this bootstrap specifier to *merge_cp_p
654 append_operand(scratch_cp, old_bs_i, merge_cp_p, merge_cp_length_p, THREAD);
655 new_bs_i = _operands_cur_length - 1;
656 }
657 }
658 return new_bs_i;
659 } // end find_or_append_operand()
660
661
662 void VM_RedefineClasses::finalize_operands_merge(const constantPoolHandle& merge_cp, TRAPS) {
663 if (merge_cp->operands() == NULL) {
664 return;
665 }
666 // Shrink the merge_cp operands
667 merge_cp->shrink_operands(_operands_cur_length, CHECK);
668
669 if (log_is_enabled(Trace, redefine, class, constantpool)) {
670 // don't want to loop unless we are tracing
671 int count = 0;
672 for (int i = 1; i < _operands_index_map_p->length(); i++) {
673 int value = _operands_index_map_p->at(i);
674 if (value != -1) {
675 log_trace(redefine, class, constantpool)("operands_index_map[%d]: old=%d new=%d", count, i, value);
676 count++;
677 }
678 }
679 }
680 // Clean-up
681 _operands_index_map_p = NULL;
682 _operands_cur_length = 0;
683 _operands_index_map_count = 0;
684 } // end finalize_operands_merge()
685
686 // Symbol* comparator for qsort
687 // The caller must have an active ResourceMark.
688 static int symcmp(const void* a, const void* b) {
689 char* astr = (*(Symbol**)a)->as_C_string();
690 char* bstr = (*(Symbol**)b)->as_C_string();
691 return strcmp(astr, bstr);
692 }
693
694 jvmtiError VM_RedefineClasses::compare_and_normalize_class_versions(
695 InstanceKlass* the_class,
696 InstanceKlass* scratch_class) {
697 int i;
698
699 // Check superclasses, or rather their names, since superclasses themselves can be
700 // requested to replace.
701 // Check for NULL superclass first since this might be java.lang.Object
702 if (the_class->super() != scratch_class->super() &&
703 (the_class->super() == NULL || scratch_class->super() == NULL ||
704 the_class->super()->name() !=
705 scratch_class->super()->name())) {
706 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_HIERARCHY_CHANGED;
707 }
708
709 // Check if the number, names and order of directly implemented interfaces are the same.
710 // I think in principle we should just check if the sets of names of directly implemented
711 // interfaces are the same, i.e. the order of declaration (which, however, if changed in the
712 // .java file, also changes in .class file) should not matter. However, comparing sets is
713 // technically a bit more difficult, and, more importantly, I am not sure at present that the
714 // order of interfaces does not matter on the implementation level, i.e. that the VM does not
715 // rely on it somewhere.
716 Array<Klass*>* k_interfaces = the_class->local_interfaces();
717 Array<Klass*>* k_new_interfaces = scratch_class->local_interfaces();
718 int n_intfs = k_interfaces->length();
719 if (n_intfs != k_new_interfaces->length()) {
720 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_HIERARCHY_CHANGED;
721 }
722 for (i = 0; i < n_intfs; i++) {
723 if (k_interfaces->at(i)->name() !=
724 k_new_interfaces->at(i)->name()) {
725 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_HIERARCHY_CHANGED;
726 }
727 }
728
729 // Check whether class is in the error init state.
730 if (the_class->is_in_error_state()) {
731 // TBD #5057930: special error code is needed in 1.6
732 return JVMTI_ERROR_INVALID_CLASS;
733 }
734
735 // Check whether the class NestHost attribute has been changed.
736 {
737 Thread* thread = Thread::current();
738 ResourceMark rm(thread);
739 JvmtiThreadState *state = JvmtiThreadState::state_for((JavaThread*)thread);
740 RedefineVerifyMark rvm(the_class, scratch_class, state);
741 u2 the_nest_host_idx = the_class->nest_host_index();
742 u2 scr_nest_host_idx = scratch_class->nest_host_index();
743
744 if (the_nest_host_idx != 0 && scr_nest_host_idx != 0) {
745 Symbol* the_sym = the_class->constants()->klass_name_at(the_nest_host_idx);
746 Symbol* scr_sym = scratch_class->constants()->klass_name_at(scr_nest_host_idx);
747 if (the_sym != scr_sym) {
748 log_trace(redefine, class, nestmates)
749 ("redefined class %s attribute change error: NestHost class: %s replaced with: %s",
750 the_class->external_name(), the_sym->as_C_string(), scr_sym->as_C_string());
751 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_CLASS_ATTRIBUTE_CHANGED;
752 }
753 } else if ((the_nest_host_idx == 0) ^ (scr_nest_host_idx == 0)) {
754 const char* action_str = (the_nest_host_idx != 0) ? "removed" : "added";
755 log_trace(redefine, class, nestmates)
756 ("redefined class %s attribute change error: NestHost attribute %s",
757 the_class->external_name(), action_str);
758 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_CLASS_ATTRIBUTE_CHANGED;
759 }
760
761 // Check whether the class NestMembers attribute has been changed.
762 Array<u2>* the_nest_members = the_class->nest_members();
763 Array<u2>* scr_nest_members = scratch_class->nest_members();
764 bool the_members_exists = the_nest_members != Universe::the_empty_short_array();
765 bool scr_members_exists = scr_nest_members != Universe::the_empty_short_array();
766
767 int members_len = the_nest_members->length();
768 if (the_members_exists && scr_members_exists) {
769 if (members_len != scr_nest_members->length()) {
770 log_trace(redefine, class, nestmates)
771 ("redefined class %s attribute change error: NestMember len=%d changed to len=%d",
772 the_class->external_name(), members_len, scr_nest_members->length());
773 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_CLASS_ATTRIBUTE_CHANGED;
774 }
775
776 // The order of entries in the NestMembers array is not specified so we
777 // have to explicitly check for the same contents. We do this by copying
778 // the referenced symbols into their own arrays, sorting them and then
779 // comparing each element pair.
780
781 Symbol** the_syms = NEW_RESOURCE_ARRAY_RETURN_NULL(Symbol*, members_len);
782 Symbol** scr_syms = NEW_RESOURCE_ARRAY_RETURN_NULL(Symbol*, members_len);
783
784 if (the_syms == NULL || scr_syms == NULL) {
785 return JVMTI_ERROR_OUT_OF_MEMORY;
786 }
787
788 for (int i = 0; i < members_len; i++) {
789 int the_cp_index = the_nest_members->at(i);
790 int scr_cp_index = scr_nest_members->at(i);
791 the_syms[i] = the_class->constants()->klass_name_at(the_cp_index);
792 scr_syms[i] = scratch_class->constants()->klass_name_at(scr_cp_index);
793 }
794
795 qsort(the_syms, members_len, sizeof(Symbol*), symcmp);
796 qsort(scr_syms, members_len, sizeof(Symbol*), symcmp);
797
798 for (int i = 0; i < members_len; i++) {
799 if (the_syms[i] != scr_syms[i]) {
800 log_trace(redefine, class, nestmates)
801 ("redefined class %s attribute change error: NestMembers[%d]: %s changed to %s",
802 the_class->external_name(), i, the_syms[i]->as_C_string(), scr_syms[i]->as_C_string());
803 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_CLASS_ATTRIBUTE_CHANGED;
804 }
805 }
806 /*
807 for (int i = 0; i < members_len; i++) {
808 int the_cp_index = the_nest_members->at(i);
809 int scr_cp_index = scr_nest_members->at(i);
810 Symbol* the_sym = the_class->constants()->klass_name_at(the_cp_index);
811 Symbol* scr_sym = scratch_class->constants()->klass_name_at(scr_cp_index);
812 if (the_sym != scr_sym) {
813 log_trace(redefine, class, nestmates)
814 ("redefined class %s attribute change error: NestMembers[%d]: %s changed to %s",
815 the_class->external_name(), i, the_sym->as_C_string(), scr_sym->as_C_string());
816 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_CLASS_ATTRIBUTE_CHANGED;
817 }
818 }
819 */
820 } else if (the_members_exists ^ scr_members_exists) {
821 const char* action_str = (the_members_exists) ? "removed" : "added";
822 log_trace(redefine, class, nestmates)
823 ("redefined class %s attribute change error: NestMembers attribute %s",
824 the_class->external_name(), action_str);
825 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_CLASS_ATTRIBUTE_CHANGED;
826 }
827 }
828
829 // Check whether class modifiers are the same.
830 jushort old_flags = (jushort) the_class->access_flags().get_flags();
831 jushort new_flags = (jushort) scratch_class->access_flags().get_flags();
832 if (old_flags != new_flags) {
833 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_CLASS_MODIFIERS_CHANGED;
834 }
835
836 // Check if the number, names, types and order of fields declared in these classes
837 // are the same.
838 JavaFieldStream old_fs(the_class);
839 JavaFieldStream new_fs(scratch_class);
840 for (; !old_fs.done() && !new_fs.done(); old_fs.next(), new_fs.next()) {
841 // access
842 old_flags = old_fs.access_flags().as_short();
843 new_flags = new_fs.access_flags().as_short();
844 if ((old_flags ^ new_flags) & JVM_RECOGNIZED_FIELD_MODIFIERS) {
845 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_SCHEMA_CHANGED;
846 }
847 // offset
848 if (old_fs.offset() != new_fs.offset()) {
849 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_SCHEMA_CHANGED;
850 }
851 // name and signature
852 Symbol* name_sym1 = the_class->constants()->symbol_at(old_fs.name_index());
853 Symbol* sig_sym1 = the_class->constants()->symbol_at(old_fs.signature_index());
854 Symbol* name_sym2 = scratch_class->constants()->symbol_at(new_fs.name_index());
855 Symbol* sig_sym2 = scratch_class->constants()->symbol_at(new_fs.signature_index());
856 if (name_sym1 != name_sym2 || sig_sym1 != sig_sym2) {
857 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_SCHEMA_CHANGED;
858 }
859 }
860
861 // If both streams aren't done then we have a differing number of
862 // fields.
863 if (!old_fs.done() || !new_fs.done()) {
864 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_SCHEMA_CHANGED;
865 }
866
867 // Do a parallel walk through the old and new methods. Detect
868 // cases where they match (exist in both), have been added in
869 // the new methods, or have been deleted (exist only in the
870 // old methods). The class file parser places methods in order
871 // by method name, but does not order overloaded methods by
872 // signature. In order to determine what fate befell the methods,
873 // this code places the overloaded new methods that have matching
874 // old methods in the same order as the old methods and places
875 // new overloaded methods at the end of overloaded methods of
876 // that name. The code for this order normalization is adapted
877 // from the algorithm used in InstanceKlass::find_method().
878 // Since we are swapping out of order entries as we find them,
879 // we only have to search forward through the overloaded methods.
880 // Methods which are added and have the same name as an existing
881 // method (but different signature) will be put at the end of
882 // the methods with that name, and the name mismatch code will
883 // handle them.
884 Array<Method*>* k_old_methods(the_class->methods());
885 Array<Method*>* k_new_methods(scratch_class->methods());
886 int n_old_methods = k_old_methods->length();
887 int n_new_methods = k_new_methods->length();
888 Thread* thread = Thread::current();
889
890 int ni = 0;
891 int oi = 0;
892 while (true) {
893 Method* k_old_method;
894 Method* k_new_method;
895 enum { matched, added, deleted, undetermined } method_was = undetermined;
896
897 if (oi >= n_old_methods) {
898 if (ni >= n_new_methods) {
899 break; // we've looked at everything, done
900 }
901 // New method at the end
902 k_new_method = k_new_methods->at(ni);
903 method_was = added;
904 } else if (ni >= n_new_methods) {
905 // Old method, at the end, is deleted
906 k_old_method = k_old_methods->at(oi);
907 method_was = deleted;
908 } else {
909 // There are more methods in both the old and new lists
910 k_old_method = k_old_methods->at(oi);
911 k_new_method = k_new_methods->at(ni);
912 if (k_old_method->name() != k_new_method->name()) {
913 // Methods are sorted by method name, so a mismatch means added
914 // or deleted
915 if (k_old_method->name()->fast_compare(k_new_method->name()) > 0) {
916 method_was = added;
917 } else {
918 method_was = deleted;
919 }
920 } else if (k_old_method->signature() == k_new_method->signature()) {
921 // Both the name and signature match
922 method_was = matched;
923 } else {
924 // The name matches, but the signature doesn't, which means we have to
925 // search forward through the new overloaded methods.
926 int nj; // outside the loop for post-loop check
927 for (nj = ni + 1; nj < n_new_methods; nj++) {
928 Method* m = k_new_methods->at(nj);
929 if (k_old_method->name() != m->name()) {
930 // reached another method name so no more overloaded methods
931 method_was = deleted;
932 break;
933 }
934 if (k_old_method->signature() == m->signature()) {
935 // found a match so swap the methods
936 k_new_methods->at_put(ni, m);
937 k_new_methods->at_put(nj, k_new_method);
938 k_new_method = m;
939 method_was = matched;
940 break;
941 }
942 }
943
944 if (nj >= n_new_methods) {
945 // reached the end without a match; so method was deleted
946 method_was = deleted;
947 }
948 }
949 }
950
951 switch (method_was) {
952 case matched:
953 // methods match, be sure modifiers do too
954 old_flags = (jushort) k_old_method->access_flags().get_flags();
955 new_flags = (jushort) k_new_method->access_flags().get_flags();
956 if ((old_flags ^ new_flags) & ~(JVM_ACC_NATIVE)) {
957 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_METHOD_MODIFIERS_CHANGED;
958 }
959 {
960 u2 new_num = k_new_method->method_idnum();
961 u2 old_num = k_old_method->method_idnum();
962 if (new_num != old_num) {
963 Method* idnum_owner = scratch_class->method_with_idnum(old_num);
964 if (idnum_owner != NULL) {
965 // There is already a method assigned this idnum -- switch them
966 // Take current and original idnum from the new_method
967 idnum_owner->set_method_idnum(new_num);
968 idnum_owner->set_orig_method_idnum(k_new_method->orig_method_idnum());
969 }
970 // Take current and original idnum from the old_method
971 k_new_method->set_method_idnum(old_num);
972 k_new_method->set_orig_method_idnum(k_old_method->orig_method_idnum());
973 if (thread->has_pending_exception()) {
974 return JVMTI_ERROR_OUT_OF_MEMORY;
975 }
976 }
977 }
978 log_trace(redefine, class, normalize)
979 ("Method matched: new: %s [%d] == old: %s [%d]",
980 k_new_method->name_and_sig_as_C_string(), ni, k_old_method->name_and_sig_as_C_string(), oi);
981 // advance to next pair of methods
982 ++oi;
983 ++ni;
984 break;
985 case added:
986 // method added, see if it is OK
987 new_flags = (jushort) k_new_method->access_flags().get_flags();
988 if ((new_flags & JVM_ACC_PRIVATE) == 0
989 // hack: private should be treated as final, but alas
990 || (new_flags & (JVM_ACC_FINAL|JVM_ACC_STATIC)) == 0
991 ) {
992 // new methods must be private
993 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_METHOD_ADDED;
994 }
995 {
996 u2 num = the_class->next_method_idnum();
997 if (num == ConstMethod::UNSET_IDNUM) {
998 // cannot add any more methods
999 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_METHOD_ADDED;
1000 }
1001 u2 new_num = k_new_method->method_idnum();
1002 Method* idnum_owner = scratch_class->method_with_idnum(num);
1003 if (idnum_owner != NULL) {
1004 // There is already a method assigned this idnum -- switch them
1005 // Take current and original idnum from the new_method
1006 idnum_owner->set_method_idnum(new_num);
1007 idnum_owner->set_orig_method_idnum(k_new_method->orig_method_idnum());
1008 }
1009 k_new_method->set_method_idnum(num);
1010 k_new_method->set_orig_method_idnum(num);
1011 if (thread->has_pending_exception()) {
1012 return JVMTI_ERROR_OUT_OF_MEMORY;
1013 }
1014 }
1015 log_trace(redefine, class, normalize)
1016 ("Method added: new: %s [%d]", k_new_method->name_and_sig_as_C_string(), ni);
1017 ++ni; // advance to next new method
1018 break;
1019 case deleted:
1020 // method deleted, see if it is OK
1021 old_flags = (jushort) k_old_method->access_flags().get_flags();
1022 if ((old_flags & JVM_ACC_PRIVATE) == 0
1023 // hack: private should be treated as final, but alas
1024 || (old_flags & (JVM_ACC_FINAL|JVM_ACC_STATIC)) == 0
1025 ) {
1026 // deleted methods must be private
1027 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_METHOD_DELETED;
1028 }
1029 log_trace(redefine, class, normalize)
1030 ("Method deleted: old: %s [%d]", k_old_method->name_and_sig_as_C_string(), oi);
1031 ++oi; // advance to next old method
1032 break;
1033 default:
1034 ShouldNotReachHere();
1035 }
1036 }
1037
1038 return JVMTI_ERROR_NONE;
1039 }
1040
1041
1042 // Find new constant pool index value for old constant pool index value
1043 // by seaching the index map. Returns zero (0) if there is no mapped
1044 // value for the old constant pool index.
1045 int VM_RedefineClasses::find_new_index(int old_index) {
1046 if (_index_map_count == 0) {
1047 // map is empty so nothing can be found
1048 return 0;
1049 }
1050
1051 if (old_index < 1 || old_index >= _index_map_p->length()) {
1052 // The old_index is out of range so it is not mapped. This should
1053 // not happen in regular constant pool merging use, but it can
1054 // happen if a corrupt annotation is processed.
1055 return 0;
1056 }
1057
1058 int value = _index_map_p->at(old_index);
1059 if (value == -1) {
1060 // the old_index is not mapped
1061 return 0;
1062 }
1063
1064 return value;
1065 } // end find_new_index()
1066
1067
1068 // Find new bootstrap specifier index value for old bootstrap specifier index
1069 // value by seaching the index map. Returns unused index (-1) if there is
1070 // no mapped value for the old bootstrap specifier index.
1071 int VM_RedefineClasses::find_new_operand_index(int old_index) {
1072 if (_operands_index_map_count == 0) {
1073 // map is empty so nothing can be found
1074 return -1;
1075 }
1076
1077 if (old_index == -1 || old_index >= _operands_index_map_p->length()) {
1078 // The old_index is out of range so it is not mapped.
1079 // This should not happen in regular constant pool merging use.
1080 return -1;
1081 }
1082
1083 int value = _operands_index_map_p->at(old_index);
1084 if (value == -1) {
1085 // the old_index is not mapped
1086 return -1;
1087 }
1088
1089 return value;
1090 } // end find_new_operand_index()
1091
1092
1093 // Returns true if the current mismatch is due to a resolved/unresolved
1094 // class pair. Otherwise, returns false.
1095 bool VM_RedefineClasses::is_unresolved_class_mismatch(const constantPoolHandle& cp1,
1096 int index1, const constantPoolHandle& cp2, int index2) {
1097
1098 jbyte t1 = cp1->tag_at(index1).value();
1099 if (t1 != JVM_CONSTANT_Class && t1 != JVM_CONSTANT_UnresolvedClass) {
1100 return false; // wrong entry type; not our special case
1101 }
1102
1103 jbyte t2 = cp2->tag_at(index2).value();
1104 if (t2 != JVM_CONSTANT_Class && t2 != JVM_CONSTANT_UnresolvedClass) {
1105 return false; // wrong entry type; not our special case
1106 }
1107
1108 if (t1 == t2) {
1109 return false; // not a mismatch; not our special case
1110 }
1111
1112 char *s1 = cp1->klass_name_at(index1)->as_C_string();
1113 char *s2 = cp2->klass_name_at(index2)->as_C_string();
1114 if (strcmp(s1, s2) != 0) {
1115 return false; // strings don't match; not our special case
1116 }
1117
1118 return true; // made it through the gauntlet; this is our special case
1119 } // end is_unresolved_class_mismatch()
1120
1121
1122 jvmtiError VM_RedefineClasses::load_new_class_versions(TRAPS) {
1123
1124 // For consistency allocate memory using os::malloc wrapper.
1125 _scratch_classes = (InstanceKlass**)
1126 os::malloc(sizeof(InstanceKlass*) * _class_count, mtClass);
1127 if (_scratch_classes == NULL) {
1128 return JVMTI_ERROR_OUT_OF_MEMORY;
1129 }
1130 // Zero initialize the _scratch_classes array.
1131 for (int i = 0; i < _class_count; i++) {
1132 _scratch_classes[i] = NULL;
1133 }
1134
1135 ResourceMark rm(THREAD);
1136
1137 JvmtiThreadState *state = JvmtiThreadState::state_for(JavaThread::current());
1138 // state can only be NULL if the current thread is exiting which
1139 // should not happen since we're trying to do a RedefineClasses
1140 guarantee(state != NULL, "exiting thread calling load_new_class_versions");
1141 for (int i = 0; i < _class_count; i++) {
1142 // Create HandleMark so that any handles created while loading new class
1143 // versions are deleted. Constant pools are deallocated while merging
1144 // constant pools
1145 HandleMark hm(THREAD);
1146 InstanceKlass* the_class = get_ik(_class_defs[i].klass);
1147 Symbol* the_class_sym = the_class->name();
1148
1149 log_debug(redefine, class, load)
1150 ("loading name=%s kind=%d (avail_mem=" UINT64_FORMAT "K)",
1151 the_class->external_name(), _class_load_kind, os::available_memory() >> 10);
1152
1153 ClassFileStream st((u1*)_class_defs[i].class_bytes,
1154 _class_defs[i].class_byte_count,
1155 "__VM_RedefineClasses__",
1156 ClassFileStream::verify);
1157
1158 // Parse the stream.
1159 Handle the_class_loader(THREAD, the_class->class_loader());
1160 Handle protection_domain(THREAD, the_class->protection_domain());
1161 // Set redefined class handle in JvmtiThreadState class.
1162 // This redefined class is sent to agent event handler for class file
1163 // load hook event.
1164 state->set_class_being_redefined(the_class, _class_load_kind);
1165
1166 InstanceKlass* scratch_class = SystemDictionary::parse_stream(
1167 the_class_sym,
1168 the_class_loader,
1169 protection_domain,
1170 &st,
1171 THREAD);
1172 // Clear class_being_redefined just to be sure.
1173 state->clear_class_being_redefined();
1174
1175 // TODO: if this is retransform, and nothing changed we can skip it
1176
1177 // Need to clean up allocated InstanceKlass if there's an error so assign
1178 // the result here. Caller deallocates all the scratch classes in case of
1179 // an error.
1180 _scratch_classes[i] = scratch_class;
1181
1182 if (HAS_PENDING_EXCEPTION) {
1183 Symbol* ex_name = PENDING_EXCEPTION->klass()->name();
1184 log_info(redefine, class, load, exceptions)("parse_stream exception: '%s'", ex_name->as_C_string());
1185 CLEAR_PENDING_EXCEPTION;
1186
1187 if (ex_name == vmSymbols::java_lang_UnsupportedClassVersionError()) {
1188 return JVMTI_ERROR_UNSUPPORTED_VERSION;
1189 } else if (ex_name == vmSymbols::java_lang_ClassFormatError()) {
1190 return JVMTI_ERROR_INVALID_CLASS_FORMAT;
1191 } else if (ex_name == vmSymbols::java_lang_ClassCircularityError()) {
1192 return JVMTI_ERROR_CIRCULAR_CLASS_DEFINITION;
1193 } else if (ex_name == vmSymbols::java_lang_NoClassDefFoundError()) {
1194 // The message will be "XXX (wrong name: YYY)"
1195 return JVMTI_ERROR_NAMES_DONT_MATCH;
1196 } else if (ex_name == vmSymbols::java_lang_OutOfMemoryError()) {
1197 return JVMTI_ERROR_OUT_OF_MEMORY;
1198 } else { // Just in case more exceptions can be thrown..
1199 return JVMTI_ERROR_FAILS_VERIFICATION;
1200 }
1201 }
1202
1203 // Ensure class is linked before redefine
1204 if (!the_class->is_linked()) {
1205 the_class->link_class(THREAD);
1206 if (HAS_PENDING_EXCEPTION) {
1207 Symbol* ex_name = PENDING_EXCEPTION->klass()->name();
1208 log_info(redefine, class, load, exceptions)("link_class exception: '%s'", ex_name->as_C_string());
1209 CLEAR_PENDING_EXCEPTION;
1210 if (ex_name == vmSymbols::java_lang_OutOfMemoryError()) {
1211 return JVMTI_ERROR_OUT_OF_MEMORY;
1212 } else {
1213 return JVMTI_ERROR_INTERNAL;
1214 }
1215 }
1216 }
1217
1218 // Do the validity checks in compare_and_normalize_class_versions()
1219 // before verifying the byte codes. By doing these checks first, we
1220 // limit the number of functions that require redirection from
1221 // the_class to scratch_class. In particular, we don't have to
1222 // modify JNI GetSuperclass() and thus won't change its performance.
1223 jvmtiError res = compare_and_normalize_class_versions(the_class,
1224 scratch_class);
1225 if (res != JVMTI_ERROR_NONE) {
1226 return res;
1227 }
1228
1229 // verify what the caller passed us
1230 {
1231 // The bug 6214132 caused the verification to fail.
1232 // Information about the_class and scratch_class is temporarily
1233 // recorded into jvmtiThreadState. This data is used to redirect
1234 // the_class to scratch_class in the JVM_* functions called by the
1235 // verifier. Please, refer to jvmtiThreadState.hpp for the detailed
1236 // description.
1237 RedefineVerifyMark rvm(the_class, scratch_class, state);
1238 Verifier::verify(
1239 scratch_class, Verifier::ThrowException, true, THREAD);
1240 }
1241
1242 if (HAS_PENDING_EXCEPTION) {
1243 Symbol* ex_name = PENDING_EXCEPTION->klass()->name();
1244 log_info(redefine, class, load, exceptions)("verify_byte_codes exception: '%s'", ex_name->as_C_string());
1245 CLEAR_PENDING_EXCEPTION;
1246 if (ex_name == vmSymbols::java_lang_OutOfMemoryError()) {
1247 return JVMTI_ERROR_OUT_OF_MEMORY;
1248 } else {
1249 // tell the caller the bytecodes are bad
1250 return JVMTI_ERROR_FAILS_VERIFICATION;
1251 }
1252 }
1253
1254 res = merge_cp_and_rewrite(the_class, scratch_class, THREAD);
1255 if (HAS_PENDING_EXCEPTION) {
1256 Symbol* ex_name = PENDING_EXCEPTION->klass()->name();
1257 log_info(redefine, class, load, exceptions)("merge_cp_and_rewrite exception: '%s'", ex_name->as_C_string());
1258 CLEAR_PENDING_EXCEPTION;
1259 if (ex_name == vmSymbols::java_lang_OutOfMemoryError()) {
1260 return JVMTI_ERROR_OUT_OF_MEMORY;
1261 } else {
1262 return JVMTI_ERROR_INTERNAL;
1263 }
1264 }
1265
1266 if (VerifyMergedCPBytecodes) {
1267 // verify what we have done during constant pool merging
1268 {
1269 RedefineVerifyMark rvm(the_class, scratch_class, state);
1270 Verifier::verify(scratch_class, Verifier::ThrowException, true, THREAD);
1271 }
1272
1273 if (HAS_PENDING_EXCEPTION) {
1274 Symbol* ex_name = PENDING_EXCEPTION->klass()->name();
1275 log_info(redefine, class, load, exceptions)
1276 ("verify_byte_codes post merge-CP exception: '%s'", ex_name->as_C_string());
1277 CLEAR_PENDING_EXCEPTION;
1278 if (ex_name == vmSymbols::java_lang_OutOfMemoryError()) {
1279 return JVMTI_ERROR_OUT_OF_MEMORY;
1280 } else {
1281 // tell the caller that constant pool merging screwed up
1282 return JVMTI_ERROR_INTERNAL;
1283 }
1284 }
1285 }
1286
1287 Rewriter::rewrite(scratch_class, THREAD);
1288 if (!HAS_PENDING_EXCEPTION) {
1289 scratch_class->link_methods(THREAD);
1290 }
1291 if (HAS_PENDING_EXCEPTION) {
1292 Symbol* ex_name = PENDING_EXCEPTION->klass()->name();
1293 log_info(redefine, class, load, exceptions)
1294 ("Rewriter::rewrite or link_methods exception: '%s'", ex_name->as_C_string());
1295 CLEAR_PENDING_EXCEPTION;
1296 if (ex_name == vmSymbols::java_lang_OutOfMemoryError()) {
1297 return JVMTI_ERROR_OUT_OF_MEMORY;
1298 } else {
1299 return JVMTI_ERROR_INTERNAL;
1300 }
1301 }
1302
1303 log_debug(redefine, class, load)
1304 ("loaded name=%s (avail_mem=" UINT64_FORMAT "K)", the_class->external_name(), os::available_memory() >> 10);
1305 }
1306
1307 return JVMTI_ERROR_NONE;
1308 }
1309
1310
1311 // Map old_index to new_index as needed. scratch_cp is only needed
1312 // for log calls.
1313 void VM_RedefineClasses::map_index(const constantPoolHandle& scratch_cp,
1314 int old_index, int new_index) {
1315 if (find_new_index(old_index) != 0) {
1316 // old_index is already mapped
1317 return;
1318 }
1319
1320 if (old_index == new_index) {
1321 // no mapping is needed
1322 return;
1323 }
1324
1325 _index_map_p->at_put(old_index, new_index);
1326 _index_map_count++;
1327
1328 log_trace(redefine, class, constantpool)
1329 ("mapped tag %d at index %d to %d", scratch_cp->tag_at(old_index).value(), old_index, new_index);
1330 } // end map_index()
1331
1332
1333 // Map old_index to new_index as needed.
1334 void VM_RedefineClasses::map_operand_index(int old_index, int new_index) {
1335 if (find_new_operand_index(old_index) != -1) {
1336 // old_index is already mapped
1337 return;
1338 }
1339
1340 if (old_index == new_index) {
1341 // no mapping is needed
1342 return;
1343 }
1344
1345 _operands_index_map_p->at_put(old_index, new_index);
1346 _operands_index_map_count++;
1347
1348 log_trace(redefine, class, constantpool)("mapped bootstrap specifier at index %d to %d", old_index, new_index);
1349 } // end map_index()
1350
1351
1352 // Merge old_cp and scratch_cp and return the results of the merge via
1353 // merge_cp_p. The number of entries in *merge_cp_p is returned via
1354 // merge_cp_length_p. The entries in old_cp occupy the same locations
1355 // in *merge_cp_p. Also creates a map of indices from entries in
1356 // scratch_cp to the corresponding entry in *merge_cp_p. Index map
1357 // entries are only created for entries in scratch_cp that occupy a
1358 // different location in *merged_cp_p.
1359 bool VM_RedefineClasses::merge_constant_pools(const constantPoolHandle& old_cp,
1360 const constantPoolHandle& scratch_cp, constantPoolHandle *merge_cp_p,
1361 int *merge_cp_length_p, TRAPS) {
1362
1363 if (merge_cp_p == NULL) {
1364 assert(false, "caller must provide scratch constantPool");
1365 return false; // robustness
1366 }
1367 if (merge_cp_length_p == NULL) {
1368 assert(false, "caller must provide scratch CP length");
1369 return false; // robustness
1370 }
1371 // Worst case we need old_cp->length() + scratch_cp()->length(),
1372 // but the caller might be smart so make sure we have at least
1373 // the minimum.
1374 if ((*merge_cp_p)->length() < old_cp->length()) {
1375 assert(false, "merge area too small");
1376 return false; // robustness
1377 }
1378
1379 log_info(redefine, class, constantpool)("old_cp_len=%d, scratch_cp_len=%d", old_cp->length(), scratch_cp->length());
1380
1381 {
1382 // Pass 0:
1383 // The old_cp is copied to *merge_cp_p; this means that any code
1384 // using old_cp does not have to change. This work looks like a
1385 // perfect fit for ConstantPool*::copy_cp_to(), but we need to
1386 // handle one special case:
1387 // - revert JVM_CONSTANT_Class to JVM_CONSTANT_UnresolvedClass
1388 // This will make verification happy.
1389
1390 int old_i; // index into old_cp
1391
1392 // index zero (0) is not used in constantPools
1393 for (old_i = 1; old_i < old_cp->length(); old_i++) {
1394 // leave debugging crumb
1395 jbyte old_tag = old_cp->tag_at(old_i).value();
1396 switch (old_tag) {
1397 case JVM_CONSTANT_Class:
1398 case JVM_CONSTANT_UnresolvedClass:
1399 // revert the copy to JVM_CONSTANT_UnresolvedClass
1400 // May be resolving while calling this so do the same for
1401 // JVM_CONSTANT_UnresolvedClass (klass_name_at() deals with transition)
1402 (*merge_cp_p)->temp_unresolved_klass_at_put(old_i,
1403 old_cp->klass_name_index_at(old_i));
1404 break;
1405
1406 case JVM_CONSTANT_Double:
1407 case JVM_CONSTANT_Long:
1408 // just copy the entry to *merge_cp_p, but double and long take
1409 // two constant pool entries
1410 ConstantPool::copy_entry_to(old_cp, old_i, *merge_cp_p, old_i, CHECK_0);
1411 old_i++;
1412 break;
1413
1414 default:
1415 // just copy the entry to *merge_cp_p
1416 ConstantPool::copy_entry_to(old_cp, old_i, *merge_cp_p, old_i, CHECK_0);
1417 break;
1418 }
1419 } // end for each old_cp entry
1420
1421 ConstantPool::copy_operands(old_cp, *merge_cp_p, CHECK_0);
1422 (*merge_cp_p)->extend_operands(scratch_cp, CHECK_0);
1423
1424 // We don't need to sanity check that *merge_cp_length_p is within
1425 // *merge_cp_p bounds since we have the minimum on-entry check above.
1426 (*merge_cp_length_p) = old_i;
1427 }
1428
1429 // merge_cp_len should be the same as old_cp->length() at this point
1430 // so this trace message is really a "warm-and-breathing" message.
1431 log_debug(redefine, class, constantpool)("after pass 0: merge_cp_len=%d", *merge_cp_length_p);
1432
1433 int scratch_i; // index into scratch_cp
1434 {
1435 // Pass 1a:
1436 // Compare scratch_cp entries to the old_cp entries that we have
1437 // already copied to *merge_cp_p. In this pass, we are eliminating
1438 // exact duplicates (matching entry at same index) so we only
1439 // compare entries in the common indice range.
1440 int increment = 1;
1441 int pass1a_length = MIN2(old_cp->length(), scratch_cp->length());
1442 for (scratch_i = 1; scratch_i < pass1a_length; scratch_i += increment) {
1443 switch (scratch_cp->tag_at(scratch_i).value()) {
1444 case JVM_CONSTANT_Double:
1445 case JVM_CONSTANT_Long:
1446 // double and long take two constant pool entries
1447 increment = 2;
1448 break;
1449
1450 default:
1451 increment = 1;
1452 break;
1453 }
1454
1455 bool match = scratch_cp->compare_entry_to(scratch_i, *merge_cp_p,
1456 scratch_i, CHECK_0);
1457 if (match) {
1458 // found a match at the same index so nothing more to do
1459 continue;
1460 } else if (is_unresolved_class_mismatch(scratch_cp, scratch_i,
1461 *merge_cp_p, scratch_i)) {
1462 // The mismatch in compare_entry_to() above is because of a
1463 // resolved versus unresolved class entry at the same index
1464 // with the same string value. Since Pass 0 reverted any
1465 // class entries to unresolved class entries in *merge_cp_p,
1466 // we go with the unresolved class entry.
1467 continue;
1468 }
1469
1470 int found_i = scratch_cp->find_matching_entry(scratch_i, *merge_cp_p,
1471 CHECK_0);
1472 if (found_i != 0) {
1473 guarantee(found_i != scratch_i,
1474 "compare_entry_to() and find_matching_entry() do not agree");
1475
1476 // Found a matching entry somewhere else in *merge_cp_p so
1477 // just need a mapping entry.
1478 map_index(scratch_cp, scratch_i, found_i);
1479 continue;
1480 }
1481
1482 // The find_matching_entry() call above could fail to find a match
1483 // due to a resolved versus unresolved class or string entry situation
1484 // like we solved above with the is_unresolved_*_mismatch() calls.
1485 // However, we would have to call is_unresolved_*_mismatch() over
1486 // all of *merge_cp_p (potentially) and that doesn't seem to be
1487 // worth the time.
1488
1489 // No match found so we have to append this entry and any unique
1490 // referenced entries to *merge_cp_p.
1491 append_entry(scratch_cp, scratch_i, merge_cp_p, merge_cp_length_p,
1492 CHECK_0);
1493 }
1494 }
1495
1496 log_debug(redefine, class, constantpool)
1497 ("after pass 1a: merge_cp_len=%d, scratch_i=%d, index_map_len=%d",
1498 *merge_cp_length_p, scratch_i, _index_map_count);
1499
1500 if (scratch_i < scratch_cp->length()) {
1501 // Pass 1b:
1502 // old_cp is smaller than scratch_cp so there are entries in
1503 // scratch_cp that we have not yet processed. We take care of
1504 // those now.
1505 int increment = 1;
1506 for (; scratch_i < scratch_cp->length(); scratch_i += increment) {
1507 switch (scratch_cp->tag_at(scratch_i).value()) {
1508 case JVM_CONSTANT_Double:
1509 case JVM_CONSTANT_Long:
1510 // double and long take two constant pool entries
1511 increment = 2;
1512 break;
1513
1514 default:
1515 increment = 1;
1516 break;
1517 }
1518
1519 int found_i =
1520 scratch_cp->find_matching_entry(scratch_i, *merge_cp_p, CHECK_0);
1521 if (found_i != 0) {
1522 // Found a matching entry somewhere else in *merge_cp_p so
1523 // just need a mapping entry.
1524 map_index(scratch_cp, scratch_i, found_i);
1525 continue;
1526 }
1527
1528 // No match found so we have to append this entry and any unique
1529 // referenced entries to *merge_cp_p.
1530 append_entry(scratch_cp, scratch_i, merge_cp_p, merge_cp_length_p,
1531 CHECK_0);
1532 }
1533
1534 log_debug(redefine, class, constantpool)
1535 ("after pass 1b: merge_cp_len=%d, scratch_i=%d, index_map_len=%d",
1536 *merge_cp_length_p, scratch_i, _index_map_count);
1537 }
1538 finalize_operands_merge(*merge_cp_p, THREAD);
1539
1540 return true;
1541 } // end merge_constant_pools()
1542
1543
1544 // Scoped object to clean up the constant pool(s) created for merging
1545 class MergeCPCleaner {
1546 ClassLoaderData* _loader_data;
1547 ConstantPool* _cp;
1548 ConstantPool* _scratch_cp;
1549 public:
1550 MergeCPCleaner(ClassLoaderData* loader_data, ConstantPool* merge_cp) :
1551 _loader_data(loader_data), _cp(merge_cp), _scratch_cp(NULL) {}
1552 ~MergeCPCleaner() {
1553 _loader_data->add_to_deallocate_list(_cp);
1554 if (_scratch_cp != NULL) {
1555 _loader_data->add_to_deallocate_list(_scratch_cp);
1556 }
1557 }
1558 void add_scratch_cp(ConstantPool* scratch_cp) { _scratch_cp = scratch_cp; }
1559 };
1560
1561 // Merge constant pools between the_class and scratch_class and
1562 // potentially rewrite bytecodes in scratch_class to use the merged
1563 // constant pool.
1564 jvmtiError VM_RedefineClasses::merge_cp_and_rewrite(
1565 InstanceKlass* the_class, InstanceKlass* scratch_class,
1566 TRAPS) {
1567 // worst case merged constant pool length is old and new combined
1568 int merge_cp_length = the_class->constants()->length()
1569 + scratch_class->constants()->length();
1570
1571 // Constant pools are not easily reused so we allocate a new one
1572 // each time.
1573 // merge_cp is created unsafe for concurrent GC processing. It
1574 // should be marked safe before discarding it. Even though
1575 // garbage, if it crosses a card boundary, it may be scanned
1576 // in order to find the start of the first complete object on the card.
1577 ClassLoaderData* loader_data = the_class->class_loader_data();
1578 ConstantPool* merge_cp_oop =
1579 ConstantPool::allocate(loader_data,
1580 merge_cp_length,
1581 CHECK_(JVMTI_ERROR_OUT_OF_MEMORY));
1582 MergeCPCleaner cp_cleaner(loader_data, merge_cp_oop);
1583
1584 HandleMark hm(THREAD); // make sure handles are cleared before
1585 // MergeCPCleaner clears out merge_cp_oop
1586 constantPoolHandle merge_cp(THREAD, merge_cp_oop);
1587
1588 // Get constants() from the old class because it could have been rewritten
1589 // while we were at a safepoint allocating a new constant pool.
1590 constantPoolHandle old_cp(THREAD, the_class->constants());
1591 constantPoolHandle scratch_cp(THREAD, scratch_class->constants());
1592
1593 // If the length changed, the class was redefined out from under us. Return
1594 // an error.
1595 if (merge_cp_length != the_class->constants()->length()
1596 + scratch_class->constants()->length()) {
1597 return JVMTI_ERROR_INTERNAL;
1598 }
1599
1600 // Update the version number of the constant pools (may keep scratch_cp)
1601 merge_cp->increment_and_save_version(old_cp->version());
1602 scratch_cp->increment_and_save_version(old_cp->version());
1603
1604 ResourceMark rm(THREAD);
1605 _index_map_count = 0;
1606 _index_map_p = new intArray(scratch_cp->length(), scratch_cp->length(), -1);
1607
1608 _operands_cur_length = ConstantPool::operand_array_length(old_cp->operands());
1609 _operands_index_map_count = 0;
1610 int operands_index_map_len = ConstantPool::operand_array_length(scratch_cp->operands());
1611 _operands_index_map_p = new intArray(operands_index_map_len, operands_index_map_len, -1);
1612
1613 // reference to the cp holder is needed for copy_operands()
1614 merge_cp->set_pool_holder(scratch_class);
1615 bool result = merge_constant_pools(old_cp, scratch_cp, &merge_cp,
1616 &merge_cp_length, THREAD);
1617 merge_cp->set_pool_holder(NULL);
1618
1619 if (!result) {
1620 // The merge can fail due to memory allocation failure or due
1621 // to robustness checks.
1622 return JVMTI_ERROR_INTERNAL;
1623 }
1624
1625 log_info(redefine, class, constantpool)("merge_cp_len=%d, index_map_len=%d", merge_cp_length, _index_map_count);
1626
1627 if (_index_map_count == 0) {
1628 // there is nothing to map between the new and merged constant pools
1629
1630 if (old_cp->length() == scratch_cp->length()) {
1631 // The old and new constant pools are the same length and the
1632 // index map is empty. This means that the three constant pools
1633 // are equivalent (but not the same). Unfortunately, the new
1634 // constant pool has not gone through link resolution nor have
1635 // the new class bytecodes gone through constant pool cache
1636 // rewriting so we can't use the old constant pool with the new
1637 // class.
1638
1639 // toss the merged constant pool at return
1640 } else if (old_cp->length() < scratch_cp->length()) {
1641 // The old constant pool has fewer entries than the new constant
1642 // pool and the index map is empty. This means the new constant
1643 // pool is a superset of the old constant pool. However, the old
1644 // class bytecodes have already gone through constant pool cache
1645 // rewriting so we can't use the new constant pool with the old
1646 // class.
1647
1648 // toss the merged constant pool at return
1649 } else {
1650 // The old constant pool has more entries than the new constant
1651 // pool and the index map is empty. This means that both the old
1652 // and merged constant pools are supersets of the new constant
1653 // pool.
1654
1655 // Replace the new constant pool with a shrunken copy of the
1656 // merged constant pool
1657 set_new_constant_pool(loader_data, scratch_class, merge_cp, merge_cp_length,
1658 CHECK_(JVMTI_ERROR_OUT_OF_MEMORY));
1659 // The new constant pool replaces scratch_cp so have cleaner clean it up.
1660 // It can't be cleaned up while there are handles to it.
1661 cp_cleaner.add_scratch_cp(scratch_cp());
1662 }
1663 } else {
1664 if (log_is_enabled(Trace, redefine, class, constantpool)) {
1665 // don't want to loop unless we are tracing
1666 int count = 0;
1667 for (int i = 1; i < _index_map_p->length(); i++) {
1668 int value = _index_map_p->at(i);
1669
1670 if (value != -1) {
1671 log_trace(redefine, class, constantpool)("index_map[%d]: old=%d new=%d", count, i, value);
1672 count++;
1673 }
1674 }
1675 }
1676
1677 // We have entries mapped between the new and merged constant pools
1678 // so we have to rewrite some constant pool references.
1679 if (!rewrite_cp_refs(scratch_class, THREAD)) {
1680 return JVMTI_ERROR_INTERNAL;
1681 }
1682
1683 // Replace the new constant pool with a shrunken copy of the
1684 // merged constant pool so now the rewritten bytecodes have
1685 // valid references; the previous new constant pool will get
1686 // GCed.
1687 set_new_constant_pool(loader_data, scratch_class, merge_cp, merge_cp_length,
1688 CHECK_(JVMTI_ERROR_OUT_OF_MEMORY));
1689 // The new constant pool replaces scratch_cp so have cleaner clean it up.
1690 // It can't be cleaned up while there are handles to it.
1691 cp_cleaner.add_scratch_cp(scratch_cp());
1692 }
1693
1694 return JVMTI_ERROR_NONE;
1695 } // end merge_cp_and_rewrite()
1696
1697
1698 // Rewrite constant pool references in klass scratch_class.
1699 bool VM_RedefineClasses::rewrite_cp_refs(InstanceKlass* scratch_class,
1700 TRAPS) {
1701
1702 // rewrite constant pool references in the nest attributes:
1703 if (!rewrite_cp_refs_in_nest_attributes(scratch_class)) {
1704 // propagate failure back to caller
1705 return false;
1706 }
1707
1708 // rewrite constant pool references in the methods:
1709 if (!rewrite_cp_refs_in_methods(scratch_class, THREAD)) {
1710 // propagate failure back to caller
1711 return false;
1712 }
1713
1714 // rewrite constant pool references in the class_annotations:
1715 if (!rewrite_cp_refs_in_class_annotations(scratch_class, THREAD)) {
1716 // propagate failure back to caller
1717 return false;
1718 }
1719
1720 // rewrite constant pool references in the fields_annotations:
1721 if (!rewrite_cp_refs_in_fields_annotations(scratch_class, THREAD)) {
1722 // propagate failure back to caller
1723 return false;
1724 }
1725
1726 // rewrite constant pool references in the methods_annotations:
1727 if (!rewrite_cp_refs_in_methods_annotations(scratch_class, THREAD)) {
1728 // propagate failure back to caller
1729 return false;
1730 }
1731
1732 // rewrite constant pool references in the methods_parameter_annotations:
1733 if (!rewrite_cp_refs_in_methods_parameter_annotations(scratch_class,
1734 THREAD)) {
1735 // propagate failure back to caller
1736 return false;
1737 }
1738
1739 // rewrite constant pool references in the methods_default_annotations:
1740 if (!rewrite_cp_refs_in_methods_default_annotations(scratch_class,
1741 THREAD)) {
1742 // propagate failure back to caller
1743 return false;
1744 }
1745
1746 // rewrite constant pool references in the class_type_annotations:
1747 if (!rewrite_cp_refs_in_class_type_annotations(scratch_class, THREAD)) {
1748 // propagate failure back to caller
1749 return false;
1750 }
1751
1752 // rewrite constant pool references in the fields_type_annotations:
1753 if (!rewrite_cp_refs_in_fields_type_annotations(scratch_class, THREAD)) {
1754 // propagate failure back to caller
1755 return false;
1756 }
1757
1758 // rewrite constant pool references in the methods_type_annotations:
1759 if (!rewrite_cp_refs_in_methods_type_annotations(scratch_class, THREAD)) {
1760 // propagate failure back to caller
1761 return false;
1762 }
1763
1764 // There can be type annotations in the Code part of a method_info attribute.
1765 // These annotations are not accessible, even by reflection.
1766 // Currently they are not even parsed by the ClassFileParser.
1767 // If runtime access is added they will also need to be rewritten.
1768
1769 // rewrite source file name index:
1770 u2 source_file_name_idx = scratch_class->source_file_name_index();
1771 if (source_file_name_idx != 0) {
1772 u2 new_source_file_name_idx = find_new_index(source_file_name_idx);
1773 if (new_source_file_name_idx != 0) {
1774 scratch_class->set_source_file_name_index(new_source_file_name_idx);
1775 }
1776 }
1777
1778 // rewrite class generic signature index:
1779 u2 generic_signature_index = scratch_class->generic_signature_index();
1780 if (generic_signature_index != 0) {
1781 u2 new_generic_signature_index = find_new_index(generic_signature_index);
1782 if (new_generic_signature_index != 0) {
1783 scratch_class->set_generic_signature_index(new_generic_signature_index);
1784 }
1785 }
1786
1787 return true;
1788 } // end rewrite_cp_refs()
1789
1790 // Rewrite constant pool references in the NestHost and NestMembers attributes.
1791 bool VM_RedefineClasses::rewrite_cp_refs_in_nest_attributes(
1792 InstanceKlass* scratch_class) {
1793
1794 u2 cp_index = scratch_class->nest_host_index();
1795 if (cp_index != 0) {
1796 scratch_class->set_nest_host_index(find_new_index(cp_index));
1797 }
1798 Array<u2>* nest_members = scratch_class->nest_members();
1799 for (int i = 0; i < nest_members->length(); i++) {
1800 u2 cp_index = nest_members->at(i);
1801 nest_members->at_put(i, find_new_index(cp_index));
1802 }
1803 return true;
1804 }
1805
1806 // Rewrite constant pool references in the methods.
1807 bool VM_RedefineClasses::rewrite_cp_refs_in_methods(
1808 InstanceKlass* scratch_class, TRAPS) {
1809
1810 Array<Method*>* methods = scratch_class->methods();
1811
1812 if (methods == NULL || methods->length() == 0) {
1813 // no methods so nothing to do
1814 return true;
1815 }
1816
1817 // rewrite constant pool references in the methods:
1818 for (int i = methods->length() - 1; i >= 0; i--) {
1819 methodHandle method(THREAD, methods->at(i));
1820 methodHandle new_method;
1821 rewrite_cp_refs_in_method(method, &new_method, THREAD);
1822 if (!new_method.is_null()) {
1823 // the method has been replaced so save the new method version
1824 // even in the case of an exception. original method is on the
1825 // deallocation list.
1826 methods->at_put(i, new_method());
1827 }
1828 if (HAS_PENDING_EXCEPTION) {
1829 Symbol* ex_name = PENDING_EXCEPTION->klass()->name();
1830 log_info(redefine, class, load, exceptions)("rewrite_cp_refs_in_method exception: '%s'", ex_name->as_C_string());
1831 // Need to clear pending exception here as the super caller sets
1832 // the JVMTI_ERROR_INTERNAL if the returned value is false.
1833 CLEAR_PENDING_EXCEPTION;
1834 return false;
1835 }
1836 }
1837
1838 return true;
1839 }
1840
1841
1842 // Rewrite constant pool references in the specific method. This code
1843 // was adapted from Rewriter::rewrite_method().
1844 void VM_RedefineClasses::rewrite_cp_refs_in_method(methodHandle method,
1845 methodHandle *new_method_p, TRAPS) {
1846
1847 *new_method_p = methodHandle(); // default is no new method
1848
1849 // We cache a pointer to the bytecodes here in code_base. If GC
1850 // moves the Method*, then the bytecodes will also move which
1851 // will likely cause a crash. We create a NoSafepointVerifier
1852 // object to detect whether we pass a possible safepoint in this
1853 // code block.
1854 NoSafepointVerifier nsv;
1855
1856 // Bytecodes and their length
1857 address code_base = method->code_base();
1858 int code_length = method->code_size();
1859
1860 int bc_length;
1861 for (int bci = 0; bci < code_length; bci += bc_length) {
1862 address bcp = code_base + bci;
1863 Bytecodes::Code c = (Bytecodes::Code)(*bcp);
1864
1865 bc_length = Bytecodes::length_for(c);
1866 if (bc_length == 0) {
1867 // More complicated bytecodes report a length of zero so
1868 // we have to try again a slightly different way.
1869 bc_length = Bytecodes::length_at(method(), bcp);
1870 }
1871
1872 assert(bc_length != 0, "impossible bytecode length");
1873
1874 switch (c) {
1875 case Bytecodes::_ldc:
1876 {
1877 int cp_index = *(bcp + 1);
1878 int new_index = find_new_index(cp_index);
1879
1880 if (StressLdcRewrite && new_index == 0) {
1881 // If we are stressing ldc -> ldc_w rewriting, then we
1882 // always need a new_index value.
1883 new_index = cp_index;
1884 }
1885 if (new_index != 0) {
1886 // the original index is mapped so we have more work to do
1887 if (!StressLdcRewrite && new_index <= max_jubyte) {
1888 // The new value can still use ldc instead of ldc_w
1889 // unless we are trying to stress ldc -> ldc_w rewriting
1890 log_trace(redefine, class, constantpool)
1891 ("%s@" INTPTR_FORMAT " old=%d, new=%d", Bytecodes::name(c), p2i(bcp), cp_index, new_index);
1892 *(bcp + 1) = new_index;
1893 } else {
1894 log_trace(redefine, class, constantpool)
1895 ("%s->ldc_w@" INTPTR_FORMAT " old=%d, new=%d", Bytecodes::name(c), p2i(bcp), cp_index, new_index);
1896 // the new value needs ldc_w instead of ldc
1897 u_char inst_buffer[4]; // max instruction size is 4 bytes
1898 bcp = (address)inst_buffer;
1899 // construct new instruction sequence
1900 *bcp = Bytecodes::_ldc_w;
1901 bcp++;
1902 // Rewriter::rewrite_method() does not rewrite ldc -> ldc_w.
1903 // See comment below for difference between put_Java_u2()
1904 // and put_native_u2().
1905 Bytes::put_Java_u2(bcp, new_index);
1906
1907 Relocator rc(method, NULL /* no RelocatorListener needed */);
1908 methodHandle m;
1909 {
1910 PauseNoSafepointVerifier pnsv(&nsv);
1911
1912 // ldc is 2 bytes and ldc_w is 3 bytes
1913 m = rc.insert_space_at(bci, 3, inst_buffer, CHECK);
1914 }
1915
1916 // return the new method so that the caller can update
1917 // the containing class
1918 *new_method_p = method = m;
1919 // switch our bytecode processing loop from the old method
1920 // to the new method
1921 code_base = method->code_base();
1922 code_length = method->code_size();
1923 bcp = code_base + bci;
1924 c = (Bytecodes::Code)(*bcp);
1925 bc_length = Bytecodes::length_for(c);
1926 assert(bc_length != 0, "sanity check");
1927 } // end we need ldc_w instead of ldc
1928 } // end if there is a mapped index
1929 } break;
1930
1931 // these bytecodes have a two-byte constant pool index
1932 case Bytecodes::_anewarray : // fall through
1933 case Bytecodes::_checkcast : // fall through
1934 case Bytecodes::_getfield : // fall through
1935 case Bytecodes::_getstatic : // fall through
1936 case Bytecodes::_instanceof : // fall through
1937 case Bytecodes::_invokedynamic : // fall through
1938 case Bytecodes::_invokeinterface: // fall through
1939 case Bytecodes::_invokespecial : // fall through
1940 case Bytecodes::_invokestatic : // fall through
1941 case Bytecodes::_invokevirtual : // fall through
1942 case Bytecodes::_ldc_w : // fall through
1943 case Bytecodes::_ldc2_w : // fall through
1944 case Bytecodes::_multianewarray : // fall through
1945 case Bytecodes::_new : // fall through
1946 case Bytecodes::_putfield : // fall through
1947 case Bytecodes::_putstatic :
1948 {
1949 address p = bcp + 1;
1950 int cp_index = Bytes::get_Java_u2(p);
1951 int new_index = find_new_index(cp_index);
1952 if (new_index != 0) {
1953 // the original index is mapped so update w/ new value
1954 log_trace(redefine, class, constantpool)
1955 ("%s@" INTPTR_FORMAT " old=%d, new=%d", Bytecodes::name(c),p2i(bcp), cp_index, new_index);
1956 // Rewriter::rewrite_method() uses put_native_u2() in this
1957 // situation because it is reusing the constant pool index
1958 // location for a native index into the ConstantPoolCache.
1959 // Since we are updating the constant pool index prior to
1960 // verification and ConstantPoolCache initialization, we
1961 // need to keep the new index in Java byte order.
1962 Bytes::put_Java_u2(p, new_index);
1963 }
1964 } break;
1965 default:
1966 break;
1967 }
1968 } // end for each bytecode
1969
1970 // We also need to rewrite the parameter name indexes, if there is
1971 // method parameter data present
1972 if(method->has_method_parameters()) {
1973 const int len = method->method_parameters_length();
1974 MethodParametersElement* elem = method->method_parameters_start();
1975
1976 for (int i = 0; i < len; i++) {
1977 const u2 cp_index = elem[i].name_cp_index;
1978 const u2 new_cp_index = find_new_index(cp_index);
1979 if (new_cp_index != 0) {
1980 elem[i].name_cp_index = new_cp_index;
1981 }
1982 }
1983 }
1984 } // end rewrite_cp_refs_in_method()
1985
1986
1987 // Rewrite constant pool references in the class_annotations field.
1988 bool VM_RedefineClasses::rewrite_cp_refs_in_class_annotations(
1989 InstanceKlass* scratch_class, TRAPS) {
1990
1991 AnnotationArray* class_annotations = scratch_class->class_annotations();
1992 if (class_annotations == NULL || class_annotations->length() == 0) {
1993 // no class_annotations so nothing to do
1994 return true;
1995 }
1996
1997 log_debug(redefine, class, annotation)("class_annotations length=%d", class_annotations->length());
1998
1999 int byte_i = 0; // byte index into class_annotations
2000 return rewrite_cp_refs_in_annotations_typeArray(class_annotations, byte_i,
2001 THREAD);
2002 }
2003
2004
2005 // Rewrite constant pool references in an annotations typeArray. This
2006 // "structure" is adapted from the RuntimeVisibleAnnotations_attribute
2007 // that is described in section 4.8.15 of the 2nd-edition of the VM spec:
2008 //
2009 // annotations_typeArray {
2010 // u2 num_annotations;
2011 // annotation annotations[num_annotations];
2012 // }
2013 //
2014 bool VM_RedefineClasses::rewrite_cp_refs_in_annotations_typeArray(
2015 AnnotationArray* annotations_typeArray, int &byte_i_ref, TRAPS) {
2016
2017 if ((byte_i_ref + 2) > annotations_typeArray->length()) {
2018 // not enough room for num_annotations field
2019 log_debug(redefine, class, annotation)("length() is too small for num_annotations field");
2020 return false;
2021 }
2022
2023 u2 num_annotations = Bytes::get_Java_u2((address)
2024 annotations_typeArray->adr_at(byte_i_ref));
2025 byte_i_ref += 2;
2026
2027 log_debug(redefine, class, annotation)("num_annotations=%d", num_annotations);
2028
2029 int calc_num_annotations = 0;
2030 for (; calc_num_annotations < num_annotations; calc_num_annotations++) {
2031 if (!rewrite_cp_refs_in_annotation_struct(annotations_typeArray,
2032 byte_i_ref, THREAD)) {
2033 log_debug(redefine, class, annotation)("bad annotation_struct at %d", calc_num_annotations);
2034 // propagate failure back to caller
2035 return false;
2036 }
2037 }
2038 assert(num_annotations == calc_num_annotations, "sanity check");
2039
2040 return true;
2041 } // end rewrite_cp_refs_in_annotations_typeArray()
2042
2043
2044 // Rewrite constant pool references in the annotation struct portion of
2045 // an annotations_typeArray. This "structure" is from section 4.8.15 of
2046 // the 2nd-edition of the VM spec:
2047 //
2048 // struct annotation {
2049 // u2 type_index;
2050 // u2 num_element_value_pairs;
2051 // {
2052 // u2 element_name_index;
2053 // element_value value;
2054 // } element_value_pairs[num_element_value_pairs];
2055 // }
2056 //
2057 bool VM_RedefineClasses::rewrite_cp_refs_in_annotation_struct(
2058 AnnotationArray* annotations_typeArray, int &byte_i_ref, TRAPS) {
2059 if ((byte_i_ref + 2 + 2) > annotations_typeArray->length()) {
2060 // not enough room for smallest annotation_struct
2061 log_debug(redefine, class, annotation)("length() is too small for annotation_struct");
2062 return false;
2063 }
2064
2065 u2 type_index = rewrite_cp_ref_in_annotation_data(annotations_typeArray,
2066 byte_i_ref, "type_index", THREAD);
2067
2068 u2 num_element_value_pairs = Bytes::get_Java_u2((address)
2069 annotations_typeArray->adr_at(byte_i_ref));
2070 byte_i_ref += 2;
2071
2072 log_debug(redefine, class, annotation)
2073 ("type_index=%d num_element_value_pairs=%d", type_index, num_element_value_pairs);
2074
2075 int calc_num_element_value_pairs = 0;
2076 for (; calc_num_element_value_pairs < num_element_value_pairs;
2077 calc_num_element_value_pairs++) {
2078 if ((byte_i_ref + 2) > annotations_typeArray->length()) {
2079 // not enough room for another element_name_index, let alone
2080 // the rest of another component
2081 log_debug(redefine, class, annotation)("length() is too small for element_name_index");
2082 return false;
2083 }
2084
2085 u2 element_name_index = rewrite_cp_ref_in_annotation_data(
2086 annotations_typeArray, byte_i_ref,
2087 "element_name_index", THREAD);
2088
2089 log_debug(redefine, class, annotation)("element_name_index=%d", element_name_index);
2090
2091 if (!rewrite_cp_refs_in_element_value(annotations_typeArray,
2092 byte_i_ref, THREAD)) {
2093 log_debug(redefine, class, annotation)("bad element_value at %d", calc_num_element_value_pairs);
2094 // propagate failure back to caller
2095 return false;
2096 }
2097 } // end for each component
2098 assert(num_element_value_pairs == calc_num_element_value_pairs,
2099 "sanity check");
2100
2101 return true;
2102 } // end rewrite_cp_refs_in_annotation_struct()
2103
2104
2105 // Rewrite a constant pool reference at the current position in
2106 // annotations_typeArray if needed. Returns the original constant
2107 // pool reference if a rewrite was not needed or the new constant
2108 // pool reference if a rewrite was needed.
2109 u2 VM_RedefineClasses::rewrite_cp_ref_in_annotation_data(
2110 AnnotationArray* annotations_typeArray, int &byte_i_ref,
2111 const char * trace_mesg, TRAPS) {
2112
2113 address cp_index_addr = (address)
2114 annotations_typeArray->adr_at(byte_i_ref);
2115 u2 old_cp_index = Bytes::get_Java_u2(cp_index_addr);
2116 u2 new_cp_index = find_new_index(old_cp_index);
2117 if (new_cp_index != 0) {
2118 log_debug(redefine, class, annotation)("mapped old %s=%d", trace_mesg, old_cp_index);
2119 Bytes::put_Java_u2(cp_index_addr, new_cp_index);
2120 old_cp_index = new_cp_index;
2121 }
2122 byte_i_ref += 2;
2123 return old_cp_index;
2124 }
2125
2126
2127 // Rewrite constant pool references in the element_value portion of an
2128 // annotations_typeArray. This "structure" is from section 4.8.15.1 of
2129 // the 2nd-edition of the VM spec:
2130 //
2131 // struct element_value {
2132 // u1 tag;
2133 // union {
2134 // u2 const_value_index;
2135 // {
2136 // u2 type_name_index;
2137 // u2 const_name_index;
2138 // } enum_const_value;
2139 // u2 class_info_index;
2140 // annotation annotation_value;
2141 // struct {
2142 // u2 num_values;
2143 // element_value values[num_values];
2144 // } array_value;
2145 // } value;
2146 // }
2147 //
2148 bool VM_RedefineClasses::rewrite_cp_refs_in_element_value(
2149 AnnotationArray* annotations_typeArray, int &byte_i_ref, TRAPS) {
2150
2151 if ((byte_i_ref + 1) > annotations_typeArray->length()) {
2152 // not enough room for a tag let alone the rest of an element_value
2153 log_debug(redefine, class, annotation)("length() is too small for a tag");
2154 return false;
2155 }
2156
2157 u1 tag = annotations_typeArray->at(byte_i_ref);
2158 byte_i_ref++;
2159 log_debug(redefine, class, annotation)("tag='%c'", tag);
2160
2161 switch (tag) {
2162 // These BaseType tag values are from Table 4.2 in VM spec:
2163 case 'B': // byte
2164 case 'C': // char
2165 case 'D': // double
2166 case 'F': // float
2167 case 'I': // int
2168 case 'J': // long
2169 case 'S': // short
2170 case 'Z': // boolean
2171
2172 // The remaining tag values are from Table 4.8 in the 2nd-edition of
2173 // the VM spec:
2174 case 's':
2175 {
2176 // For the above tag values (including the BaseType values),
2177 // value.const_value_index is right union field.
2178
2179 if ((byte_i_ref + 2) > annotations_typeArray->length()) {
2180 // not enough room for a const_value_index
2181 log_debug(redefine, class, annotation)("length() is too small for a const_value_index");
2182 return false;
2183 }
2184
2185 u2 const_value_index = rewrite_cp_ref_in_annotation_data(
2186 annotations_typeArray, byte_i_ref,
2187 "const_value_index", THREAD);
2188
2189 log_debug(redefine, class, annotation)("const_value_index=%d", const_value_index);
2190 } break;
2191
2192 case 'e':
2193 {
2194 // for the above tag value, value.enum_const_value is right union field
2195
2196 if ((byte_i_ref + 4) > annotations_typeArray->length()) {
2197 // not enough room for a enum_const_value
2198 log_debug(redefine, class, annotation)("length() is too small for a enum_const_value");
2199 return false;
2200 }
2201
2202 u2 type_name_index = rewrite_cp_ref_in_annotation_data(
2203 annotations_typeArray, byte_i_ref,
2204 "type_name_index", THREAD);
2205
2206 u2 const_name_index = rewrite_cp_ref_in_annotation_data(
2207 annotations_typeArray, byte_i_ref,
2208 "const_name_index", THREAD);
2209
2210 log_debug(redefine, class, annotation)
2211 ("type_name_index=%d const_name_index=%d", type_name_index, const_name_index);
2212 } break;
2213
2214 case 'c':
2215 {
2216 // for the above tag value, value.class_info_index is right union field
2217
2218 if ((byte_i_ref + 2) > annotations_typeArray->length()) {
2219 // not enough room for a class_info_index
2220 log_debug(redefine, class, annotation)("length() is too small for a class_info_index");
2221 return false;
2222 }
2223
2224 u2 class_info_index = rewrite_cp_ref_in_annotation_data(
2225 annotations_typeArray, byte_i_ref,
2226 "class_info_index", THREAD);
2227
2228 log_debug(redefine, class, annotation)("class_info_index=%d", class_info_index);
2229 } break;
2230
2231 case '@':
2232 // For the above tag value, value.attr_value is the right union
2233 // field. This is a nested annotation.
2234 if (!rewrite_cp_refs_in_annotation_struct(annotations_typeArray,
2235 byte_i_ref, THREAD)) {
2236 // propagate failure back to caller
2237 return false;
2238 }
2239 break;
2240
2241 case '[':
2242 {
2243 if ((byte_i_ref + 2) > annotations_typeArray->length()) {
2244 // not enough room for a num_values field
2245 log_debug(redefine, class, annotation)("length() is too small for a num_values field");
2246 return false;
2247 }
2248
2249 // For the above tag value, value.array_value is the right union
2250 // field. This is an array of nested element_value.
2251 u2 num_values = Bytes::get_Java_u2((address)
2252 annotations_typeArray->adr_at(byte_i_ref));
2253 byte_i_ref += 2;
2254 log_debug(redefine, class, annotation)("num_values=%d", num_values);
2255
2256 int calc_num_values = 0;
2257 for (; calc_num_values < num_values; calc_num_values++) {
2258 if (!rewrite_cp_refs_in_element_value(
2259 annotations_typeArray, byte_i_ref, THREAD)) {
2260 log_debug(redefine, class, annotation)("bad nested element_value at %d", calc_num_values);
2261 // propagate failure back to caller
2262 return false;
2263 }
2264 }
2265 assert(num_values == calc_num_values, "sanity check");
2266 } break;
2267
2268 default:
2269 log_debug(redefine, class, annotation)("bad tag=0x%x", tag);
2270 return false;
2271 } // end decode tag field
2272
2273 return true;
2274 } // end rewrite_cp_refs_in_element_value()
2275
2276
2277 // Rewrite constant pool references in a fields_annotations field.
2278 bool VM_RedefineClasses::rewrite_cp_refs_in_fields_annotations(
2279 InstanceKlass* scratch_class, TRAPS) {
2280
2281 Array<AnnotationArray*>* fields_annotations = scratch_class->fields_annotations();
2282
2283 if (fields_annotations == NULL || fields_annotations->length() == 0) {
2284 // no fields_annotations so nothing to do
2285 return true;
2286 }
2287
2288 log_debug(redefine, class, annotation)("fields_annotations length=%d", fields_annotations->length());
2289
2290 for (int i = 0; i < fields_annotations->length(); i++) {
2291 AnnotationArray* field_annotations = fields_annotations->at(i);
2292 if (field_annotations == NULL || field_annotations->length() == 0) {
2293 // this field does not have any annotations so skip it
2294 continue;
2295 }
2296
2297 int byte_i = 0; // byte index into field_annotations
2298 if (!rewrite_cp_refs_in_annotations_typeArray(field_annotations, byte_i,
2299 THREAD)) {
2300 log_debug(redefine, class, annotation)("bad field_annotations at %d", i);
2301 // propagate failure back to caller
2302 return false;
2303 }
2304 }
2305
2306 return true;
2307 } // end rewrite_cp_refs_in_fields_annotations()
2308
2309
2310 // Rewrite constant pool references in a methods_annotations field.
2311 bool VM_RedefineClasses::rewrite_cp_refs_in_methods_annotations(
2312 InstanceKlass* scratch_class, TRAPS) {
2313
2314 for (int i = 0; i < scratch_class->methods()->length(); i++) {
2315 Method* m = scratch_class->methods()->at(i);
2316 AnnotationArray* method_annotations = m->constMethod()->method_annotations();
2317
2318 if (method_annotations == NULL || method_annotations->length() == 0) {
2319 // this method does not have any annotations so skip it
2320 continue;
2321 }
2322
2323 int byte_i = 0; // byte index into method_annotations
2324 if (!rewrite_cp_refs_in_annotations_typeArray(method_annotations, byte_i,
2325 THREAD)) {
2326 log_debug(redefine, class, annotation)("bad method_annotations at %d", i);
2327 // propagate failure back to caller
2328 return false;
2329 }
2330 }
2331
2332 return true;
2333 } // end rewrite_cp_refs_in_methods_annotations()
2334
2335
2336 // Rewrite constant pool references in a methods_parameter_annotations
2337 // field. This "structure" is adapted from the
2338 // RuntimeVisibleParameterAnnotations_attribute described in section
2339 // 4.8.17 of the 2nd-edition of the VM spec:
2340 //
2341 // methods_parameter_annotations_typeArray {
2342 // u1 num_parameters;
2343 // {
2344 // u2 num_annotations;
2345 // annotation annotations[num_annotations];
2346 // } parameter_annotations[num_parameters];
2347 // }
2348 //
2349 bool VM_RedefineClasses::rewrite_cp_refs_in_methods_parameter_annotations(
2350 InstanceKlass* scratch_class, TRAPS) {
2351
2352 for (int i = 0; i < scratch_class->methods()->length(); i++) {
2353 Method* m = scratch_class->methods()->at(i);
2354 AnnotationArray* method_parameter_annotations = m->constMethod()->parameter_annotations();
2355 if (method_parameter_annotations == NULL
2356 || method_parameter_annotations->length() == 0) {
2357 // this method does not have any parameter annotations so skip it
2358 continue;
2359 }
2360
2361 if (method_parameter_annotations->length() < 1) {
2362 // not enough room for a num_parameters field
2363 log_debug(redefine, class, annotation)("length() is too small for a num_parameters field at %d", i);
2364 return false;
2365 }
2366
2367 int byte_i = 0; // byte index into method_parameter_annotations
2368
2369 u1 num_parameters = method_parameter_annotations->at(byte_i);
2370 byte_i++;
2371
2372 log_debug(redefine, class, annotation)("num_parameters=%d", num_parameters);
2373
2374 int calc_num_parameters = 0;
2375 for (; calc_num_parameters < num_parameters; calc_num_parameters++) {
2376 if (!rewrite_cp_refs_in_annotations_typeArray(
2377 method_parameter_annotations, byte_i, THREAD)) {
2378 log_debug(redefine, class, annotation)("bad method_parameter_annotations at %d", calc_num_parameters);
2379 // propagate failure back to caller
2380 return false;
2381 }
2382 }
2383 assert(num_parameters == calc_num_parameters, "sanity check");
2384 }
2385
2386 return true;
2387 } // end rewrite_cp_refs_in_methods_parameter_annotations()
2388
2389
2390 // Rewrite constant pool references in a methods_default_annotations
2391 // field. This "structure" is adapted from the AnnotationDefault_attribute
2392 // that is described in section 4.8.19 of the 2nd-edition of the VM spec:
2393 //
2394 // methods_default_annotations_typeArray {
2395 // element_value default_value;
2396 // }
2397 //
2398 bool VM_RedefineClasses::rewrite_cp_refs_in_methods_default_annotations(
2399 InstanceKlass* scratch_class, TRAPS) {
2400
2401 for (int i = 0; i < scratch_class->methods()->length(); i++) {
2402 Method* m = scratch_class->methods()->at(i);
2403 AnnotationArray* method_default_annotations = m->constMethod()->default_annotations();
2404 if (method_default_annotations == NULL
2405 || method_default_annotations->length() == 0) {
2406 // this method does not have any default annotations so skip it
2407 continue;
2408 }
2409
2410 int byte_i = 0; // byte index into method_default_annotations
2411
2412 if (!rewrite_cp_refs_in_element_value(
2413 method_default_annotations, byte_i, THREAD)) {
2414 log_debug(redefine, class, annotation)("bad default element_value at %d", i);
2415 // propagate failure back to caller
2416 return false;
2417 }
2418 }
2419
2420 return true;
2421 } // end rewrite_cp_refs_in_methods_default_annotations()
2422
2423
2424 // Rewrite constant pool references in a class_type_annotations field.
2425 bool VM_RedefineClasses::rewrite_cp_refs_in_class_type_annotations(
2426 InstanceKlass* scratch_class, TRAPS) {
2427
2428 AnnotationArray* class_type_annotations = scratch_class->class_type_annotations();
2429 if (class_type_annotations == NULL || class_type_annotations->length() == 0) {
2430 // no class_type_annotations so nothing to do
2431 return true;
2432 }
2433
2434 log_debug(redefine, class, annotation)("class_type_annotations length=%d", class_type_annotations->length());
2435
2436 int byte_i = 0; // byte index into class_type_annotations
2437 return rewrite_cp_refs_in_type_annotations_typeArray(class_type_annotations,
2438 byte_i, "ClassFile", THREAD);
2439 } // end rewrite_cp_refs_in_class_type_annotations()
2440
2441
2442 // Rewrite constant pool references in a fields_type_annotations field.
2443 bool VM_RedefineClasses::rewrite_cp_refs_in_fields_type_annotations(
2444 InstanceKlass* scratch_class, TRAPS) {
2445
2446 Array<AnnotationArray*>* fields_type_annotations = scratch_class->fields_type_annotations();
2447 if (fields_type_annotations == NULL || fields_type_annotations->length() == 0) {
2448 // no fields_type_annotations so nothing to do
2449 return true;
2450 }
2451
2452 log_debug(redefine, class, annotation)("fields_type_annotations length=%d", fields_type_annotations->length());
2453
2454 for (int i = 0; i < fields_type_annotations->length(); i++) {
2455 AnnotationArray* field_type_annotations = fields_type_annotations->at(i);
2456 if (field_type_annotations == NULL || field_type_annotations->length() == 0) {
2457 // this field does not have any annotations so skip it
2458 continue;
2459 }
2460
2461 int byte_i = 0; // byte index into field_type_annotations
2462 if (!rewrite_cp_refs_in_type_annotations_typeArray(field_type_annotations,
2463 byte_i, "field_info", THREAD)) {
2464 log_debug(redefine, class, annotation)("bad field_type_annotations at %d", i);
2465 // propagate failure back to caller
2466 return false;
2467 }
2468 }
2469
2470 return true;
2471 } // end rewrite_cp_refs_in_fields_type_annotations()
2472
2473
2474 // Rewrite constant pool references in a methods_type_annotations field.
2475 bool VM_RedefineClasses::rewrite_cp_refs_in_methods_type_annotations(
2476 InstanceKlass* scratch_class, TRAPS) {
2477
2478 for (int i = 0; i < scratch_class->methods()->length(); i++) {
2479 Method* m = scratch_class->methods()->at(i);
2480 AnnotationArray* method_type_annotations = m->constMethod()->type_annotations();
2481
2482 if (method_type_annotations == NULL || method_type_annotations->length() == 0) {
2483 // this method does not have any annotations so skip it
2484 continue;
2485 }
2486
2487 log_debug(redefine, class, annotation)("methods type_annotations length=%d", method_type_annotations->length());
2488
2489 int byte_i = 0; // byte index into method_type_annotations
2490 if (!rewrite_cp_refs_in_type_annotations_typeArray(method_type_annotations,
2491 byte_i, "method_info", THREAD)) {
2492 log_debug(redefine, class, annotation)("bad method_type_annotations at %d", i);
2493 // propagate failure back to caller
2494 return false;
2495 }
2496 }
2497
2498 return true;
2499 } // end rewrite_cp_refs_in_methods_type_annotations()
2500
2501
2502 // Rewrite constant pool references in a type_annotations
2503 // field. This "structure" is adapted from the
2504 // RuntimeVisibleTypeAnnotations_attribute described in
2505 // section 4.7.20 of the Java SE 8 Edition of the VM spec:
2506 //
2507 // type_annotations_typeArray {
2508 // u2 num_annotations;
2509 // type_annotation annotations[num_annotations];
2510 // }
2511 //
2512 bool VM_RedefineClasses::rewrite_cp_refs_in_type_annotations_typeArray(
2513 AnnotationArray* type_annotations_typeArray, int &byte_i_ref,
2514 const char * location_mesg, TRAPS) {
2515
2516 if ((byte_i_ref + 2) > type_annotations_typeArray->length()) {
2517 // not enough room for num_annotations field
2518 log_debug(redefine, class, annotation)("length() is too small for num_annotations field");
2519 return false;
2520 }
2521
2522 u2 num_annotations = Bytes::get_Java_u2((address)
2523 type_annotations_typeArray->adr_at(byte_i_ref));
2524 byte_i_ref += 2;
2525
2526 log_debug(redefine, class, annotation)("num_type_annotations=%d", num_annotations);
2527
2528 int calc_num_annotations = 0;
2529 for (; calc_num_annotations < num_annotations; calc_num_annotations++) {
2530 if (!rewrite_cp_refs_in_type_annotation_struct(type_annotations_typeArray,
2531 byte_i_ref, location_mesg, THREAD)) {
2532 log_debug(redefine, class, annotation)("bad type_annotation_struct at %d", calc_num_annotations);
2533 // propagate failure back to caller
2534 return false;
2535 }
2536 }
2537 assert(num_annotations == calc_num_annotations, "sanity check");
2538
2539 if (byte_i_ref != type_annotations_typeArray->length()) {
2540 log_debug(redefine, class, annotation)
2541 ("read wrong amount of bytes at end of processing type_annotations_typeArray (%d of %d bytes were read)",
2542 byte_i_ref, type_annotations_typeArray->length());
2543 return false;
2544 }
2545
2546 return true;
2547 } // end rewrite_cp_refs_in_type_annotations_typeArray()
2548
2549
2550 // Rewrite constant pool references in a type_annotation
2551 // field. This "structure" is adapted from the
2552 // RuntimeVisibleTypeAnnotations_attribute described in
2553 // section 4.7.20 of the Java SE 8 Edition of the VM spec:
2554 //
2555 // type_annotation {
2556 // u1 target_type;
2557 // union {
2558 // type_parameter_target;
2559 // supertype_target;
2560 // type_parameter_bound_target;
2561 // empty_target;
2562 // method_formal_parameter_target;
2563 // throws_target;
2564 // localvar_target;
2565 // catch_target;
2566 // offset_target;
2567 // type_argument_target;
2568 // } target_info;
2569 // type_path target_path;
2570 // annotation anno;
2571 // }
2572 //
2573 bool VM_RedefineClasses::rewrite_cp_refs_in_type_annotation_struct(
2574 AnnotationArray* type_annotations_typeArray, int &byte_i_ref,
2575 const char * location_mesg, TRAPS) {
2576
2577 if (!skip_type_annotation_target(type_annotations_typeArray,
2578 byte_i_ref, location_mesg, THREAD)) {
2579 return false;
2580 }
2581
2582 if (!skip_type_annotation_type_path(type_annotations_typeArray,
2583 byte_i_ref, THREAD)) {
2584 return false;
2585 }
2586
2587 if (!rewrite_cp_refs_in_annotation_struct(type_annotations_typeArray,
2588 byte_i_ref, THREAD)) {
2589 return false;
2590 }
2591
2592 return true;
2593 } // end rewrite_cp_refs_in_type_annotation_struct()
2594
2595
2596 // Read, verify and skip over the target_type and target_info part
2597 // so that rewriting can continue in the later parts of the struct.
2598 //
2599 // u1 target_type;
2600 // union {
2601 // type_parameter_target;
2602 // supertype_target;
2603 // type_parameter_bound_target;
2604 // empty_target;
2605 // method_formal_parameter_target;
2606 // throws_target;
2607 // localvar_target;
2608 // catch_target;
2609 // offset_target;
2610 // type_argument_target;
2611 // } target_info;
2612 //
2613 bool VM_RedefineClasses::skip_type_annotation_target(
2614 AnnotationArray* type_annotations_typeArray, int &byte_i_ref,
2615 const char * location_mesg, TRAPS) {
2616
2617 if ((byte_i_ref + 1) > type_annotations_typeArray->length()) {
2618 // not enough room for a target_type let alone the rest of a type_annotation
2619 log_debug(redefine, class, annotation)("length() is too small for a target_type");
2620 return false;
2621 }
2622
2623 u1 target_type = type_annotations_typeArray->at(byte_i_ref);
2624 byte_i_ref += 1;
2625 log_debug(redefine, class, annotation)("target_type=0x%.2x", target_type);
2626 log_debug(redefine, class, annotation)("location=%s", location_mesg);
2627
2628 // Skip over target_info
2629 switch (target_type) {
2630 case 0x00:
2631 // kind: type parameter declaration of generic class or interface
2632 // location: ClassFile
2633 case 0x01:
2634 // kind: type parameter declaration of generic method or constructor
2635 // location: method_info
2636
2637 {
2638 // struct:
2639 // type_parameter_target {
2640 // u1 type_parameter_index;
2641 // }
2642 //
2643 if ((byte_i_ref + 1) > type_annotations_typeArray->length()) {
2644 log_debug(redefine, class, annotation)("length() is too small for a type_parameter_target");
2645 return false;
2646 }
2647
2648 u1 type_parameter_index = type_annotations_typeArray->at(byte_i_ref);
2649 byte_i_ref += 1;
2650
2651 log_debug(redefine, class, annotation)("type_parameter_target: type_parameter_index=%d", type_parameter_index);
2652 } break;
2653
2654 case 0x10:
2655 // kind: type in extends clause of class or interface declaration
2656 // (including the direct superclass of an anonymous class declaration),
2657 // or in implements clause of interface declaration
2658 // location: ClassFile
2659
2660 {
2661 // struct:
2662 // supertype_target {
2663 // u2 supertype_index;
2664 // }
2665 //
2666 if ((byte_i_ref + 2) > type_annotations_typeArray->length()) {
2667 log_debug(redefine, class, annotation)("length() is too small for a supertype_target");
2668 return false;
2669 }
2670
2671 u2 supertype_index = Bytes::get_Java_u2((address)
2672 type_annotations_typeArray->adr_at(byte_i_ref));
2673 byte_i_ref += 2;
2674
2675 log_debug(redefine, class, annotation)("supertype_target: supertype_index=%d", supertype_index);
2676 } break;
2677
2678 case 0x11:
2679 // kind: type in bound of type parameter declaration of generic class or interface
2680 // location: ClassFile
2681 case 0x12:
2682 // kind: type in bound of type parameter declaration of generic method or constructor
2683 // location: method_info
2684
2685 {
2686 // struct:
2687 // type_parameter_bound_target {
2688 // u1 type_parameter_index;
2689 // u1 bound_index;
2690 // }
2691 //
2692 if ((byte_i_ref + 2) > type_annotations_typeArray->length()) {
2693 log_debug(redefine, class, annotation)("length() is too small for a type_parameter_bound_target");
2694 return false;
2695 }
2696
2697 u1 type_parameter_index = type_annotations_typeArray->at(byte_i_ref);
2698 byte_i_ref += 1;
2699 u1 bound_index = type_annotations_typeArray->at(byte_i_ref);
2700 byte_i_ref += 1;
2701
2702 log_debug(redefine, class, annotation)
2703 ("type_parameter_bound_target: type_parameter_index=%d, bound_index=%d", type_parameter_index, bound_index);
2704 } break;
2705
2706 case 0x13:
2707 // kind: type in field declaration
2708 // location: field_info
2709 case 0x14:
2710 // kind: return type of method, or type of newly constructed object
2711 // location: method_info
2712 case 0x15:
2713 // kind: receiver type of method or constructor
2714 // location: method_info
2715
2716 {
2717 // struct:
2718 // empty_target {
2719 // }
2720 //
2721 log_debug(redefine, class, annotation)("empty_target");
2722 } break;
2723
2724 case 0x16:
2725 // kind: type in formal parameter declaration of method, constructor, or lambda expression
2726 // location: method_info
2727
2728 {
2729 // struct:
2730 // formal_parameter_target {
2731 // u1 formal_parameter_index;
2732 // }
2733 //
2734 if ((byte_i_ref + 1) > type_annotations_typeArray->length()) {
2735 log_debug(redefine, class, annotation)("length() is too small for a formal_parameter_target");
2736 return false;
2737 }
2738
2739 u1 formal_parameter_index = type_annotations_typeArray->at(byte_i_ref);
2740 byte_i_ref += 1;
2741
2742 log_debug(redefine, class, annotation)
2743 ("formal_parameter_target: formal_parameter_index=%d", formal_parameter_index);
2744 } break;
2745
2746 case 0x17:
2747 // kind: type in throws clause of method or constructor
2748 // location: method_info
2749
2750 {
2751 // struct:
2752 // throws_target {
2753 // u2 throws_type_index
2754 // }
2755 //
2756 if ((byte_i_ref + 2) > type_annotations_typeArray->length()) {
2757 log_debug(redefine, class, annotation)("length() is too small for a throws_target");
2758 return false;
2759 }
2760
2761 u2 throws_type_index = Bytes::get_Java_u2((address)
2762 type_annotations_typeArray->adr_at(byte_i_ref));
2763 byte_i_ref += 2;
2764
2765 log_debug(redefine, class, annotation)("throws_target: throws_type_index=%d", throws_type_index);
2766 } break;
2767
2768 case 0x40:
2769 // kind: type in local variable declaration
2770 // location: Code
2771 case 0x41:
2772 // kind: type in resource variable declaration
2773 // location: Code
2774
2775 {
2776 // struct:
2777 // localvar_target {
2778 // u2 table_length;
2779 // struct {
2780 // u2 start_pc;
2781 // u2 length;
2782 // u2 index;
2783 // } table[table_length];
2784 // }
2785 //
2786 if ((byte_i_ref + 2) > type_annotations_typeArray->length()) {
2787 // not enough room for a table_length let alone the rest of a localvar_target
2788 log_debug(redefine, class, annotation)("length() is too small for a localvar_target table_length");
2789 return false;
2790 }
2791
2792 u2 table_length = Bytes::get_Java_u2((address)
2793 type_annotations_typeArray->adr_at(byte_i_ref));
2794 byte_i_ref += 2;
2795
2796 log_debug(redefine, class, annotation)("localvar_target: table_length=%d", table_length);
2797
2798 int table_struct_size = 2 + 2 + 2; // 3 u2 variables per table entry
2799 int table_size = table_length * table_struct_size;
2800
2801 if ((byte_i_ref + table_size) > type_annotations_typeArray->length()) {
2802 // not enough room for a table
2803 log_debug(redefine, class, annotation)("length() is too small for a table array of length %d", table_length);
2804 return false;
2805 }
2806
2807 // Skip over table
2808 byte_i_ref += table_size;
2809 } break;
2810
2811 case 0x42:
2812 // kind: type in exception parameter declaration
2813 // location: Code
2814
2815 {
2816 // struct:
2817 // catch_target {
2818 // u2 exception_table_index;
2819 // }
2820 //
2821 if ((byte_i_ref + 2) > type_annotations_typeArray->length()) {
2822 log_debug(redefine, class, annotation)("length() is too small for a catch_target");
2823 return false;
2824 }
2825
2826 u2 exception_table_index = Bytes::get_Java_u2((address)
2827 type_annotations_typeArray->adr_at(byte_i_ref));
2828 byte_i_ref += 2;
2829
2830 log_debug(redefine, class, annotation)("catch_target: exception_table_index=%d", exception_table_index);
2831 } break;
2832
2833 case 0x43:
2834 // kind: type in instanceof expression
2835 // location: Code
2836 case 0x44:
2837 // kind: type in new expression
2838 // location: Code
2839 case 0x45:
2840 // kind: type in method reference expression using ::new
2841 // location: Code
2842 case 0x46:
2843 // kind: type in method reference expression using ::Identifier
2844 // location: Code
2845
2846 {
2847 // struct:
2848 // offset_target {
2849 // u2 offset;
2850 // }
2851 //
2852 if ((byte_i_ref + 2) > type_annotations_typeArray->length()) {
2853 log_debug(redefine, class, annotation)("length() is too small for a offset_target");
2854 return false;
2855 }
2856
2857 u2 offset = Bytes::get_Java_u2((address)
2858 type_annotations_typeArray->adr_at(byte_i_ref));
2859 byte_i_ref += 2;
2860
2861 log_debug(redefine, class, annotation)("offset_target: offset=%d", offset);
2862 } break;
2863
2864 case 0x47:
2865 // kind: type in cast expression
2866 // location: Code
2867 case 0x48:
2868 // kind: type argument for generic constructor in new expression or
2869 // explicit constructor invocation statement
2870 // location: Code
2871 case 0x49:
2872 // kind: type argument for generic method in method invocation expression
2873 // location: Code
2874 case 0x4A:
2875 // kind: type argument for generic constructor in method reference expression using ::new
2876 // location: Code
2877 case 0x4B:
2878 // kind: type argument for generic method in method reference expression using ::Identifier
2879 // location: Code
2880
2881 {
2882 // struct:
2883 // type_argument_target {
2884 // u2 offset;
2885 // u1 type_argument_index;
2886 // }
2887 //
2888 if ((byte_i_ref + 3) > type_annotations_typeArray->length()) {
2889 log_debug(redefine, class, annotation)("length() is too small for a type_argument_target");
2890 return false;
2891 }
2892
2893 u2 offset = Bytes::get_Java_u2((address)
2894 type_annotations_typeArray->adr_at(byte_i_ref));
2895 byte_i_ref += 2;
2896 u1 type_argument_index = type_annotations_typeArray->at(byte_i_ref);
2897 byte_i_ref += 1;
2898
2899 log_debug(redefine, class, annotation)
2900 ("type_argument_target: offset=%d, type_argument_index=%d", offset, type_argument_index);
2901 } break;
2902
2903 default:
2904 log_debug(redefine, class, annotation)("unknown target_type");
2905 #ifdef ASSERT
2906 ShouldNotReachHere();
2907 #endif
2908 return false;
2909 }
2910
2911 return true;
2912 } // end skip_type_annotation_target()
2913
2914
2915 // Read, verify and skip over the type_path part so that rewriting
2916 // can continue in the later parts of the struct.
2917 //
2918 // type_path {
2919 // u1 path_length;
2920 // {
2921 // u1 type_path_kind;
2922 // u1 type_argument_index;
2923 // } path[path_length];
2924 // }
2925 //
2926 bool VM_RedefineClasses::skip_type_annotation_type_path(
2927 AnnotationArray* type_annotations_typeArray, int &byte_i_ref, TRAPS) {
2928
2929 if ((byte_i_ref + 1) > type_annotations_typeArray->length()) {
2930 // not enough room for a path_length let alone the rest of the type_path
2931 log_debug(redefine, class, annotation)("length() is too small for a type_path");
2932 return false;
2933 }
2934
2935 u1 path_length = type_annotations_typeArray->at(byte_i_ref);
2936 byte_i_ref += 1;
2937
2938 log_debug(redefine, class, annotation)("type_path: path_length=%d", path_length);
2939
2940 int calc_path_length = 0;
2941 for (; calc_path_length < path_length; calc_path_length++) {
2942 if ((byte_i_ref + 1 + 1) > type_annotations_typeArray->length()) {
2943 // not enough room for a path
2944 log_debug(redefine, class, annotation)
2945 ("length() is too small for path entry %d of %d", calc_path_length, path_length);
2946 return false;
2947 }
2948
2949 u1 type_path_kind = type_annotations_typeArray->at(byte_i_ref);
2950 byte_i_ref += 1;
2951 u1 type_argument_index = type_annotations_typeArray->at(byte_i_ref);
2952 byte_i_ref += 1;
2953
2954 log_debug(redefine, class, annotation)
2955 ("type_path: path[%d]: type_path_kind=%d, type_argument_index=%d",
2956 calc_path_length, type_path_kind, type_argument_index);
2957
2958 if (type_path_kind > 3 || (type_path_kind != 3 && type_argument_index != 0)) {
2959 // not enough room for a path
2960 log_debug(redefine, class, annotation)("inconsistent type_path values");
2961 return false;
2962 }
2963 }
2964 assert(path_length == calc_path_length, "sanity check");
2965
2966 return true;
2967 } // end skip_type_annotation_type_path()
2968
2969
2970 // Rewrite constant pool references in the method's stackmap table.
2971 // These "structures" are adapted from the StackMapTable_attribute that
2972 // is described in section 4.8.4 of the 6.0 version of the VM spec
2973 // (dated 2005.10.26):
2974 // file:///net/quincunx.sfbay/export/gbracha/ClassFile-Java6.pdf
2975 //
2976 // stack_map {
2977 // u2 number_of_entries;
2978 // stack_map_frame entries[number_of_entries];
2979 // }
2980 //
2981 void VM_RedefineClasses::rewrite_cp_refs_in_stack_map_table(
2982 const methodHandle& method, TRAPS) {
2983
2984 if (!method->has_stackmap_table()) {
2985 return;
2986 }
2987
2988 AnnotationArray* stackmap_data = method->stackmap_data();
2989 address stackmap_p = (address)stackmap_data->adr_at(0);
2990 address stackmap_end = stackmap_p + stackmap_data->length();
2991
2992 assert(stackmap_p + 2 <= stackmap_end, "no room for number_of_entries");
2993 u2 number_of_entries = Bytes::get_Java_u2(stackmap_p);
2994 stackmap_p += 2;
2995
2996 log_debug(redefine, class, stackmap)("number_of_entries=%u", number_of_entries);
2997
2998 // walk through each stack_map_frame
2999 u2 calc_number_of_entries = 0;
3000 for (; calc_number_of_entries < number_of_entries; calc_number_of_entries++) {
3001 // The stack_map_frame structure is a u1 frame_type followed by
3002 // 0 or more bytes of data:
3003 //
3004 // union stack_map_frame {
3005 // same_frame;
3006 // same_locals_1_stack_item_frame;
3007 // same_locals_1_stack_item_frame_extended;
3008 // chop_frame;
3009 // same_frame_extended;
3010 // append_frame;
3011 // full_frame;
3012 // }
3013
3014 assert(stackmap_p + 1 <= stackmap_end, "no room for frame_type");
3015 u1 frame_type = *stackmap_p;
3016 stackmap_p++;
3017
3018 // same_frame {
3019 // u1 frame_type = SAME; /* 0-63 */
3020 // }
3021 if (frame_type <= 63) {
3022 // nothing more to do for same_frame
3023 }
3024
3025 // same_locals_1_stack_item_frame {
3026 // u1 frame_type = SAME_LOCALS_1_STACK_ITEM; /* 64-127 */
3027 // verification_type_info stack[1];
3028 // }
3029 else if (frame_type >= 64 && frame_type <= 127) {
3030 rewrite_cp_refs_in_verification_type_info(stackmap_p, stackmap_end,
3031 calc_number_of_entries, frame_type, THREAD);
3032 }
3033
3034 // reserved for future use
3035 else if (frame_type >= 128 && frame_type <= 246) {
3036 // nothing more to do for reserved frame_types
3037 }
3038
3039 // same_locals_1_stack_item_frame_extended {
3040 // u1 frame_type = SAME_LOCALS_1_STACK_ITEM_EXTENDED; /* 247 */
3041 // u2 offset_delta;
3042 // verification_type_info stack[1];
3043 // }
3044 else if (frame_type == 247) {
3045 stackmap_p += 2;
3046 rewrite_cp_refs_in_verification_type_info(stackmap_p, stackmap_end,
3047 calc_number_of_entries, frame_type, THREAD);
3048 }
3049
3050 // chop_frame {
3051 // u1 frame_type = CHOP; /* 248-250 */
3052 // u2 offset_delta;
3053 // }
3054 else if (frame_type >= 248 && frame_type <= 250) {
3055 stackmap_p += 2;
3056 }
3057
3058 // same_frame_extended {
3059 // u1 frame_type = SAME_FRAME_EXTENDED; /* 251*/
3060 // u2 offset_delta;
3061 // }
3062 else if (frame_type == 251) {
3063 stackmap_p += 2;
3064 }
3065
3066 // append_frame {
3067 // u1 frame_type = APPEND; /* 252-254 */
3068 // u2 offset_delta;
3069 // verification_type_info locals[frame_type - 251];
3070 // }
3071 else if (frame_type >= 252 && frame_type <= 254) {
3072 assert(stackmap_p + 2 <= stackmap_end,
3073 "no room for offset_delta");
3074 stackmap_p += 2;
3075 u1 len = frame_type - 251;
3076 for (u1 i = 0; i < len; i++) {
3077 rewrite_cp_refs_in_verification_type_info(stackmap_p, stackmap_end,
3078 calc_number_of_entries, frame_type, THREAD);
3079 }
3080 }
3081
3082 // full_frame {
3083 // u1 frame_type = FULL_FRAME; /* 255 */
3084 // u2 offset_delta;
3085 // u2 number_of_locals;
3086 // verification_type_info locals[number_of_locals];
3087 // u2 number_of_stack_items;
3088 // verification_type_info stack[number_of_stack_items];
3089 // }
3090 else if (frame_type == 255) {
3091 assert(stackmap_p + 2 + 2 <= stackmap_end,
3092 "no room for smallest full_frame");
3093 stackmap_p += 2;
3094
3095 u2 number_of_locals = Bytes::get_Java_u2(stackmap_p);
3096 stackmap_p += 2;
3097
3098 for (u2 locals_i = 0; locals_i < number_of_locals; locals_i++) {
3099 rewrite_cp_refs_in_verification_type_info(stackmap_p, stackmap_end,
3100 calc_number_of_entries, frame_type, THREAD);
3101 }
3102
3103 // Use the largest size for the number_of_stack_items, but only get
3104 // the right number of bytes.
3105 u2 number_of_stack_items = Bytes::get_Java_u2(stackmap_p);
3106 stackmap_p += 2;
3107
3108 for (u2 stack_i = 0; stack_i < number_of_stack_items; stack_i++) {
3109 rewrite_cp_refs_in_verification_type_info(stackmap_p, stackmap_end,
3110 calc_number_of_entries, frame_type, THREAD);
3111 }
3112 }
3113 } // end while there is a stack_map_frame
3114 assert(number_of_entries == calc_number_of_entries, "sanity check");
3115 } // end rewrite_cp_refs_in_stack_map_table()
3116
3117
3118 // Rewrite constant pool references in the verification type info
3119 // portion of the method's stackmap table. These "structures" are
3120 // adapted from the StackMapTable_attribute that is described in
3121 // section 4.8.4 of the 6.0 version of the VM spec (dated 2005.10.26):
3122 // file:///net/quincunx.sfbay/export/gbracha/ClassFile-Java6.pdf
3123 //
3124 // The verification_type_info structure is a u1 tag followed by 0 or
3125 // more bytes of data:
3126 //
3127 // union verification_type_info {
3128 // Top_variable_info;
3129 // Integer_variable_info;
3130 // Float_variable_info;
3131 // Long_variable_info;
3132 // Double_variable_info;
3133 // Null_variable_info;
3134 // UninitializedThis_variable_info;
3135 // Object_variable_info;
3136 // Uninitialized_variable_info;
3137 // }
3138 //
3139 void VM_RedefineClasses::rewrite_cp_refs_in_verification_type_info(
3140 address& stackmap_p_ref, address stackmap_end, u2 frame_i,
3141 u1 frame_type, TRAPS) {
3142
3143 assert(stackmap_p_ref + 1 <= stackmap_end, "no room for tag");
3144 u1 tag = *stackmap_p_ref;
3145 stackmap_p_ref++;
3146
3147 switch (tag) {
3148 // Top_variable_info {
3149 // u1 tag = ITEM_Top; /* 0 */
3150 // }
3151 // verificationType.hpp has zero as ITEM_Bogus instead of ITEM_Top
3152 case 0: // fall through
3153
3154 // Integer_variable_info {
3155 // u1 tag = ITEM_Integer; /* 1 */
3156 // }
3157 case ITEM_Integer: // fall through
3158
3159 // Float_variable_info {
3160 // u1 tag = ITEM_Float; /* 2 */
3161 // }
3162 case ITEM_Float: // fall through
3163
3164 // Double_variable_info {
3165 // u1 tag = ITEM_Double; /* 3 */
3166 // }
3167 case ITEM_Double: // fall through
3168
3169 // Long_variable_info {
3170 // u1 tag = ITEM_Long; /* 4 */
3171 // }
3172 case ITEM_Long: // fall through
3173
3174 // Null_variable_info {
3175 // u1 tag = ITEM_Null; /* 5 */
3176 // }
3177 case ITEM_Null: // fall through
3178
3179 // UninitializedThis_variable_info {
3180 // u1 tag = ITEM_UninitializedThis; /* 6 */
3181 // }
3182 case ITEM_UninitializedThis:
3183 // nothing more to do for the above tag types
3184 break;
3185
3186 // Object_variable_info {
3187 // u1 tag = ITEM_Object; /* 7 */
3188 // u2 cpool_index;
3189 // }
3190 case ITEM_Object:
3191 {
3192 assert(stackmap_p_ref + 2 <= stackmap_end, "no room for cpool_index");
3193 u2 cpool_index = Bytes::get_Java_u2(stackmap_p_ref);
3194 u2 new_cp_index = find_new_index(cpool_index);
3195 if (new_cp_index != 0) {
3196 log_debug(redefine, class, stackmap)("mapped old cpool_index=%d", cpool_index);
3197 Bytes::put_Java_u2(stackmap_p_ref, new_cp_index);
3198 cpool_index = new_cp_index;
3199 }
3200 stackmap_p_ref += 2;
3201
3202 log_debug(redefine, class, stackmap)
3203 ("frame_i=%u, frame_type=%u, cpool_index=%d", frame_i, frame_type, cpool_index);
3204 } break;
3205
3206 // Uninitialized_variable_info {
3207 // u1 tag = ITEM_Uninitialized; /* 8 */
3208 // u2 offset;
3209 // }
3210 case ITEM_Uninitialized:
3211 assert(stackmap_p_ref + 2 <= stackmap_end, "no room for offset");
3212 stackmap_p_ref += 2;
3213 break;
3214
3215 default:
3216 log_debug(redefine, class, stackmap)("frame_i=%u, frame_type=%u, bad tag=0x%x", frame_i, frame_type, tag);
3217 ShouldNotReachHere();
3218 break;
3219 } // end switch (tag)
3220 } // end rewrite_cp_refs_in_verification_type_info()
3221
3222
3223 // Change the constant pool associated with klass scratch_class to
3224 // scratch_cp. If shrink is true, then scratch_cp_length elements
3225 // are copied from scratch_cp to a smaller constant pool and the
3226 // smaller constant pool is associated with scratch_class.
3227 void VM_RedefineClasses::set_new_constant_pool(
3228 ClassLoaderData* loader_data,
3229 InstanceKlass* scratch_class, constantPoolHandle scratch_cp,
3230 int scratch_cp_length, TRAPS) {
3231 assert(scratch_cp->length() >= scratch_cp_length, "sanity check");
3232
3233 // scratch_cp is a merged constant pool and has enough space for a
3234 // worst case merge situation. We want to associate the minimum
3235 // sized constant pool with the klass to save space.
3236 ConstantPool* cp = ConstantPool::allocate(loader_data, scratch_cp_length, CHECK);
3237 constantPoolHandle smaller_cp(THREAD, cp);
3238
3239 // preserve version() value in the smaller copy
3240 int version = scratch_cp->version();
3241 assert(version != 0, "sanity check");
3242 smaller_cp->set_version(version);
3243
3244 // attach klass to new constant pool
3245 // reference to the cp holder is needed for copy_operands()
3246 smaller_cp->set_pool_holder(scratch_class);
3247
3248 scratch_cp->copy_cp_to(1, scratch_cp_length - 1, smaller_cp, 1, THREAD);
3249 if (HAS_PENDING_EXCEPTION) {
3250 // Exception is handled in the caller
3251 loader_data->add_to_deallocate_list(smaller_cp());
3252 return;
3253 }
3254 scratch_cp = smaller_cp;
3255
3256 // attach new constant pool to klass
3257 scratch_class->set_constants(scratch_cp());
3258 scratch_cp->initialize_unresolved_klasses(loader_data, CHECK);
3259
3260 int i; // for portability
3261
3262 // update each field in klass to use new constant pool indices as needed
3263 for (JavaFieldStream fs(scratch_class); !fs.done(); fs.next()) {
3264 jshort cur_index = fs.name_index();
3265 jshort new_index = find_new_index(cur_index);
3266 if (new_index != 0) {
3267 log_trace(redefine, class, constantpool)("field-name_index change: %d to %d", cur_index, new_index);
3268 fs.set_name_index(new_index);
3269 }
3270 cur_index = fs.signature_index();
3271 new_index = find_new_index(cur_index);
3272 if (new_index != 0) {
3273 log_trace(redefine, class, constantpool)("field-signature_index change: %d to %d", cur_index, new_index);
3274 fs.set_signature_index(new_index);
3275 }
3276 cur_index = fs.initval_index();
3277 new_index = find_new_index(cur_index);
3278 if (new_index != 0) {
3279 log_trace(redefine, class, constantpool)("field-initval_index change: %d to %d", cur_index, new_index);
3280 fs.set_initval_index(new_index);
3281 }
3282 cur_index = fs.generic_signature_index();
3283 new_index = find_new_index(cur_index);
3284 if (new_index != 0) {
3285 log_trace(redefine, class, constantpool)("field-generic_signature change: %d to %d", cur_index, new_index);
3286 fs.set_generic_signature_index(new_index);
3287 }
3288 } // end for each field
3289
3290 // Update constant pool indices in the inner classes info to use
3291 // new constant indices as needed. The inner classes info is a
3292 // quadruple:
3293 // (inner_class_info, outer_class_info, inner_name, inner_access_flags)
3294 InnerClassesIterator iter(scratch_class);
3295 for (; !iter.done(); iter.next()) {
3296 int cur_index = iter.inner_class_info_index();
3297 if (cur_index == 0) {
3298 continue; // JVM spec. allows null inner class refs so skip it
3299 }
3300 int new_index = find_new_index(cur_index);
3301 if (new_index != 0) {
3302 log_trace(redefine, class, constantpool)("inner_class_info change: %d to %d", cur_index, new_index);
3303 iter.set_inner_class_info_index(new_index);
3304 }
3305 cur_index = iter.outer_class_info_index();
3306 new_index = find_new_index(cur_index);
3307 if (new_index != 0) {
3308 log_trace(redefine, class, constantpool)("outer_class_info change: %d to %d", cur_index, new_index);
3309 iter.set_outer_class_info_index(new_index);
3310 }
3311 cur_index = iter.inner_name_index();
3312 new_index = find_new_index(cur_index);
3313 if (new_index != 0) {
3314 log_trace(redefine, class, constantpool)("inner_name change: %d to %d", cur_index, new_index);
3315 iter.set_inner_name_index(new_index);
3316 }
3317 } // end for each inner class
3318
3319 // Attach each method in klass to the new constant pool and update
3320 // to use new constant pool indices as needed:
3321 Array<Method*>* methods = scratch_class->methods();
3322 for (i = methods->length() - 1; i >= 0; i--) {
3323 methodHandle method(THREAD, methods->at(i));
3324 method->set_constants(scratch_cp());
3325
3326 int new_index = find_new_index(method->name_index());
3327 if (new_index != 0) {
3328 log_trace(redefine, class, constantpool)
3329 ("method-name_index change: %d to %d", method->name_index(), new_index);
3330 method->set_name_index(new_index);
3331 }
3332 new_index = find_new_index(method->signature_index());
3333 if (new_index != 0) {
3334 log_trace(redefine, class, constantpool)
3335 ("method-signature_index change: %d to %d", method->signature_index(), new_index);
3336 method->set_signature_index(new_index);
3337 }
3338 new_index = find_new_index(method->generic_signature_index());
3339 if (new_index != 0) {
3340 log_trace(redefine, class, constantpool)
3341 ("method-generic_signature_index change: %d to %d", method->generic_signature_index(), new_index);
3342 method->set_generic_signature_index(new_index);
3343 }
3344
3345 // Update constant pool indices in the method's checked exception
3346 // table to use new constant indices as needed.
3347 int cext_length = method->checked_exceptions_length();
3348 if (cext_length > 0) {
3349 CheckedExceptionElement * cext_table =
3350 method->checked_exceptions_start();
3351 for (int j = 0; j < cext_length; j++) {
3352 int cur_index = cext_table[j].class_cp_index;
3353 int new_index = find_new_index(cur_index);
3354 if (new_index != 0) {
3355 log_trace(redefine, class, constantpool)("cext-class_cp_index change: %d to %d", cur_index, new_index);
3356 cext_table[j].class_cp_index = (u2)new_index;
3357 }
3358 } // end for each checked exception table entry
3359 } // end if there are checked exception table entries
3360
3361 // Update each catch type index in the method's exception table
3362 // to use new constant pool indices as needed. The exception table
3363 // holds quadruple entries of the form:
3364 // (beg_bci, end_bci, handler_bci, klass_index)
3365
3366 ExceptionTable ex_table(method());
3367 int ext_length = ex_table.length();
3368
3369 for (int j = 0; j < ext_length; j ++) {
3370 int cur_index = ex_table.catch_type_index(j);
3371 int new_index = find_new_index(cur_index);
3372 if (new_index != 0) {
3373 log_trace(redefine, class, constantpool)("ext-klass_index change: %d to %d", cur_index, new_index);
3374 ex_table.set_catch_type_index(j, new_index);
3375 }
3376 } // end for each exception table entry
3377
3378 // Update constant pool indices in the method's local variable
3379 // table to use new constant indices as needed. The local variable
3380 // table hold sextuple entries of the form:
3381 // (start_pc, length, name_index, descriptor_index, signature_index, slot)
3382 int lvt_length = method->localvariable_table_length();
3383 if (lvt_length > 0) {
3384 LocalVariableTableElement * lv_table =
3385 method->localvariable_table_start();
3386 for (int j = 0; j < lvt_length; j++) {
3387 int cur_index = lv_table[j].name_cp_index;
3388 int new_index = find_new_index(cur_index);
3389 if (new_index != 0) {
3390 log_trace(redefine, class, constantpool)("lvt-name_cp_index change: %d to %d", cur_index, new_index);
3391 lv_table[j].name_cp_index = (u2)new_index;
3392 }
3393 cur_index = lv_table[j].descriptor_cp_index;
3394 new_index = find_new_index(cur_index);
3395 if (new_index != 0) {
3396 log_trace(redefine, class, constantpool)("lvt-descriptor_cp_index change: %d to %d", cur_index, new_index);
3397 lv_table[j].descriptor_cp_index = (u2)new_index;
3398 }
3399 cur_index = lv_table[j].signature_cp_index;
3400 new_index = find_new_index(cur_index);
3401 if (new_index != 0) {
3402 log_trace(redefine, class, constantpool)("lvt-signature_cp_index change: %d to %d", cur_index, new_index);
3403 lv_table[j].signature_cp_index = (u2)new_index;
3404 }
3405 } // end for each local variable table entry
3406 } // end if there are local variable table entries
3407
3408 rewrite_cp_refs_in_stack_map_table(method, THREAD);
3409 } // end for each method
3410 } // end set_new_constant_pool()
3411
3412
3413 // Unevolving classes may point to methods of the_class directly
3414 // from their constant pool caches, itables, and/or vtables. We
3415 // use the ClassLoaderDataGraph::classes_do() facility and this helper
3416 // to fix up these pointers.
3417
3418 // Adjust cpools and vtables closure
3419 void VM_RedefineClasses::AdjustCpoolCacheAndVtable::do_klass(Klass* k) {
3420
3421 // This is a very busy routine. We don't want too much tracing
3422 // printed out.
3423 bool trace_name_printed = false;
3424 InstanceKlass *the_class = InstanceKlass::cast(_the_class);
3425
3426 // If the class being redefined is java.lang.Object, we need to fix all
3427 // array class vtables also
3428 if (k->is_array_klass() && _the_class == SystemDictionary::Object_klass()) {
3429 k->vtable().adjust_method_entries(the_class, &trace_name_printed);
3430
3431 } else if (k->is_instance_klass()) {
3432 HandleMark hm(_thread);
3433 InstanceKlass *ik = InstanceKlass::cast(k);
3434
3435 // HotSpot specific optimization! HotSpot does not currently
3436 // support delegation from the bootstrap class loader to a
3437 // user-defined class loader. This means that if the bootstrap
3438 // class loader is the initiating class loader, then it will also
3439 // be the defining class loader. This also means that classes
3440 // loaded by the bootstrap class loader cannot refer to classes
3441 // loaded by a user-defined class loader. Note: a user-defined
3442 // class loader can delegate to the bootstrap class loader.
3443 //
3444 // If the current class being redefined has a user-defined class
3445 // loader as its defining class loader, then we can skip all
3446 // classes loaded by the bootstrap class loader.
3447 bool is_user_defined = (_the_class->class_loader() != NULL);
3448 if (is_user_defined && ik->class_loader() == NULL) {
3449 return;
3450 }
3451
3452 // Fix the vtable embedded in the_class and subclasses of the_class,
3453 // if one exists. We discard scratch_class and we don't keep an
3454 // InstanceKlass around to hold obsolete methods so we don't have
3455 // any other InstanceKlass embedded vtables to update. The vtable
3456 // holds the Method*s for virtual (but not final) methods.
3457 // Default methods, or concrete methods in interfaces are stored
3458 // in the vtable, so if an interface changes we need to check
3459 // adjust_method_entries() for every InstanceKlass, which will also
3460 // adjust the default method vtable indices.
3461 // We also need to adjust any default method entries that are
3462 // not yet in the vtable, because the vtable setup is in progress.
3463 // This must be done after we adjust the default_methods and
3464 // default_vtable_indices for methods already in the vtable.
3465 // If redefining Unsafe, walk all the vtables looking for entries.
3466 if (ik->vtable_length() > 0 && (_the_class->is_interface()
3467 || _the_class == SystemDictionary::internal_Unsafe_klass()
3468 || ik->is_subtype_of(_the_class))) {
3469 // ik->vtable() creates a wrapper object; rm cleans it up
3470 ResourceMark rm(_thread);
3471
3472 ik->vtable().adjust_method_entries(the_class, &trace_name_printed);
3473 ik->adjust_default_methods(the_class, &trace_name_printed);
3474 }
3475
3476 // If the current class has an itable and we are either redefining an
3477 // interface or if the current class is a subclass of the_class, then
3478 // we potentially have to fix the itable. If we are redefining an
3479 // interface, then we have to call adjust_method_entries() for
3480 // every InstanceKlass that has an itable since there isn't a
3481 // subclass relationship between an interface and an InstanceKlass.
3482 // If redefining Unsafe, walk all the itables looking for entries.
3483 if (ik->itable_length() > 0 && (_the_class->is_interface()
3484 || _the_class == SystemDictionary::internal_Unsafe_klass()
3485 || ik->is_subclass_of(_the_class))) {
3486 ResourceMark rm(_thread);
3487 ik->itable().adjust_method_entries(the_class, &trace_name_printed);
3488 }
3489
3490 // The constant pools in other classes (other_cp) can refer to
3491 // methods in the_class. We have to update method information in
3492 // other_cp's cache. If other_cp has a previous version, then we
3493 // have to repeat the process for each previous version. The
3494 // constant pool cache holds the Method*s for non-virtual
3495 // methods and for virtual, final methods.
3496 //
3497 // Special case: if the current class is the_class, then new_cp
3498 // has already been attached to the_class and old_cp has already
3499 // been added as a previous version. The new_cp doesn't have any
3500 // cached references to old methods so it doesn't need to be
3501 // updated. We can simply start with the previous version(s) in
3502 // that case.
3503 constantPoolHandle other_cp;
3504 ConstantPoolCache* cp_cache;
3505
3506 if (ik != _the_class) {
3507 // this klass' constant pool cache may need adjustment
3508 other_cp = constantPoolHandle(ik->constants());
3509 cp_cache = other_cp->cache();
3510 if (cp_cache != NULL) {
3511 cp_cache->adjust_method_entries(the_class, &trace_name_printed);
3512 }
3513 }
3514
3515 // the previous versions' constant pool caches may need adjustment
3516 for (InstanceKlass* pv_node = ik->previous_versions();
3517 pv_node != NULL;
3518 pv_node = pv_node->previous_versions()) {
3519 cp_cache = pv_node->constants()->cache();
3520 if (cp_cache != NULL) {
3521 cp_cache->adjust_method_entries(pv_node, &trace_name_printed);
3522 }
3523 }
3524 }
3525 }
3526
3527 // Clean method data for this class
3528 void VM_RedefineClasses::MethodDataCleaner::do_klass(Klass* k) {
3529 if (k->is_instance_klass()) {
3530 InstanceKlass *ik = InstanceKlass::cast(k);
3531 // Clean MethodData of this class's methods so they don't refer to
3532 // old methods that are no longer running.
3533 Array<Method*>* methods = ik->methods();
3534 int num_methods = methods->length();
3535 for (int index = 0; index < num_methods; ++index) {
3536 if (methods->at(index)->method_data() != NULL) {
3537 methods->at(index)->method_data()->clean_weak_method_links();
3538 }
3539 }
3540 }
3541 }
3542
3543 void VM_RedefineClasses::update_jmethod_ids() {
3544 for (int j = 0; j < _matching_methods_length; ++j) {
3545 Method* old_method = _matching_old_methods[j];
3546 jmethodID jmid = old_method->find_jmethod_id_or_null();
3547 if (jmid != NULL) {
3548 // There is a jmethodID, change it to point to the new method
3549 methodHandle new_method_h(_matching_new_methods[j]);
3550 Method::change_method_associated_with_jmethod_id(jmid, new_method_h());
3551 assert(Method::resolve_jmethod_id(jmid) == _matching_new_methods[j],
3552 "should be replaced");
3553 }
3554 }
3555 }
3556
3557 int VM_RedefineClasses::check_methods_and_mark_as_obsolete() {
3558 int emcp_method_count = 0;
3559 int obsolete_count = 0;
3560 int old_index = 0;
3561 for (int j = 0; j < _matching_methods_length; ++j, ++old_index) {
3562 Method* old_method = _matching_old_methods[j];
3563 Method* new_method = _matching_new_methods[j];
3564 Method* old_array_method;
3565
3566 // Maintain an old_index into the _old_methods array by skipping
3567 // deleted methods
3568 while ((old_array_method = _old_methods->at(old_index)) != old_method) {
3569 ++old_index;
3570 }
3571
3572 if (MethodComparator::methods_EMCP(old_method, new_method)) {
3573 // The EMCP definition from JSR-163 requires the bytecodes to be
3574 // the same with the exception of constant pool indices which may
3575 // differ. However, the constants referred to by those indices
3576 // must be the same.
3577 //
3578 // We use methods_EMCP() for comparison since constant pool
3579 // merging can remove duplicate constant pool entries that were
3580 // present in the old method and removed from the rewritten new
3581 // method. A faster binary comparison function would consider the
3582 // old and new methods to be different when they are actually
3583 // EMCP.
3584 //
3585 // The old and new methods are EMCP and you would think that we
3586 // could get rid of one of them here and now and save some space.
3587 // However, the concept of EMCP only considers the bytecodes and
3588 // the constant pool entries in the comparison. Other things,
3589 // e.g., the line number table (LNT) or the local variable table
3590 // (LVT) don't count in the comparison. So the new (and EMCP)
3591 // method can have a new LNT that we need so we can't just
3592 // overwrite the new method with the old method.
3593 //
3594 // When this routine is called, we have already attached the new
3595 // methods to the_class so the old methods are effectively
3596 // overwritten. However, if an old method is still executing,
3597 // then the old method cannot be collected until sometime after
3598 // the old method call has returned. So the overwriting of old
3599 // methods by new methods will save us space except for those
3600 // (hopefully few) old methods that are still executing.
3601 //
3602 // A method refers to a ConstMethod* and this presents another
3603 // possible avenue to space savings. The ConstMethod* in the
3604 // new method contains possibly new attributes (LNT, LVT, etc).
3605 // At first glance, it seems possible to save space by replacing
3606 // the ConstMethod* in the old method with the ConstMethod*
3607 // from the new method. The old and new methods would share the
3608 // same ConstMethod* and we would save the space occupied by
3609 // the old ConstMethod*. However, the ConstMethod* contains
3610 // a back reference to the containing method. Sharing the
3611 // ConstMethod* between two methods could lead to confusion in
3612 // the code that uses the back reference. This would lead to
3613 // brittle code that could be broken in non-obvious ways now or
3614 // in the future.
3615 //
3616 // Another possibility is to copy the ConstMethod* from the new
3617 // method to the old method and then overwrite the new method with
3618 // the old method. Since the ConstMethod* contains the bytecodes
3619 // for the method embedded in the oop, this option would change
3620 // the bytecodes out from under any threads executing the old
3621 // method and make the thread's bcp invalid. Since EMCP requires
3622 // that the bytecodes be the same modulo constant pool indices, it
3623 // is straight forward to compute the correct new bcp in the new
3624 // ConstMethod* from the old bcp in the old ConstMethod*. The
3625 // time consuming part would be searching all the frames in all
3626 // of the threads to find all of the calls to the old method.
3627 //
3628 // It looks like we will have to live with the limited savings
3629 // that we get from effectively overwriting the old methods
3630 // when the new methods are attached to the_class.
3631
3632 // Count number of methods that are EMCP. The method will be marked
3633 // old but not obsolete if it is EMCP.
3634 emcp_method_count++;
3635
3636 // An EMCP method is _not_ obsolete. An obsolete method has a
3637 // different jmethodID than the current method. An EMCP method
3638 // has the same jmethodID as the current method. Having the
3639 // same jmethodID for all EMCP versions of a method allows for
3640 // a consistent view of the EMCP methods regardless of which
3641 // EMCP method you happen to have in hand. For example, a
3642 // breakpoint set in one EMCP method will work for all EMCP
3643 // versions of the method including the current one.
3644 } else {
3645 // mark obsolete methods as such
3646 old_method->set_is_obsolete();
3647 obsolete_count++;
3648
3649 // obsolete methods need a unique idnum so they become new entries in
3650 // the jmethodID cache in InstanceKlass
3651 assert(old_method->method_idnum() == new_method->method_idnum(), "must match");
3652 u2 num = InstanceKlass::cast(_the_class)->next_method_idnum();
3653 if (num != ConstMethod::UNSET_IDNUM) {
3654 old_method->set_method_idnum(num);
3655 }
3656
3657 // With tracing we try not to "yack" too much. The position of
3658 // this trace assumes there are fewer obsolete methods than
3659 // EMCP methods.
3660 if (log_is_enabled(Trace, redefine, class, obsolete, mark)) {
3661 ResourceMark rm;
3662 log_trace(redefine, class, obsolete, mark)
3663 ("mark %s(%s) as obsolete", old_method->name()->as_C_string(), old_method->signature()->as_C_string());
3664 }
3665 }
3666 old_method->set_is_old();
3667 }
3668 for (int i = 0; i < _deleted_methods_length; ++i) {
3669 Method* old_method = _deleted_methods[i];
3670
3671 assert(!old_method->has_vtable_index(),
3672 "cannot delete methods with vtable entries");;
3673
3674 // Mark all deleted methods as old, obsolete and deleted
3675 old_method->set_is_deleted();
3676 old_method->set_is_old();
3677 old_method->set_is_obsolete();
3678 ++obsolete_count;
3679 // With tracing we try not to "yack" too much. The position of
3680 // this trace assumes there are fewer obsolete methods than
3681 // EMCP methods.
3682 if (log_is_enabled(Trace, redefine, class, obsolete, mark)) {
3683 ResourceMark rm;
3684 log_trace(redefine, class, obsolete, mark)
3685 ("mark deleted %s(%s) as obsolete", old_method->name()->as_C_string(), old_method->signature()->as_C_string());
3686 }
3687 }
3688 assert((emcp_method_count + obsolete_count) == _old_methods->length(),
3689 "sanity check");
3690 log_trace(redefine, class, obsolete, mark)("EMCP_cnt=%d, obsolete_cnt=%d", emcp_method_count, obsolete_count);
3691 return emcp_method_count;
3692 }
3693
3694 // This internal class transfers the native function registration from old methods
3695 // to new methods. It is designed to handle both the simple case of unchanged
3696 // native methods and the complex cases of native method prefixes being added and/or
3697 // removed.
3698 // It expects only to be used during the VM_RedefineClasses op (a safepoint).
3699 //
3700 // This class is used after the new methods have been installed in "the_class".
3701 //
3702 // So, for example, the following must be handled. Where 'm' is a method and
3703 // a number followed by an underscore is a prefix.
3704 //
3705 // Old Name New Name
3706 // Simple transfer to new method m -> m
3707 // Add prefix m -> 1_m
3708 // Remove prefix 1_m -> m
3709 // Simultaneous add of prefixes m -> 3_2_1_m
3710 // Simultaneous removal of prefixes 3_2_1_m -> m
3711 // Simultaneous add and remove 1_m -> 2_m
3712 // Same, caused by prefix removal only 3_2_1_m -> 3_2_m
3713 //
3714 class TransferNativeFunctionRegistration {
3715 private:
3716 InstanceKlass* the_class;
3717 int prefix_count;
3718 char** prefixes;
3719
3720 // Recursively search the binary tree of possibly prefixed method names.
3721 // Iteration could be used if all agents were well behaved. Full tree walk is
3722 // more resilent to agents not cleaning up intermediate methods.
3723 // Branch at each depth in the binary tree is:
3724 // (1) without the prefix.
3725 // (2) with the prefix.
3726 // where 'prefix' is the prefix at that 'depth' (first prefix, second prefix,...)
3727 Method* search_prefix_name_space(int depth, char* name_str, size_t name_len,
3728 Symbol* signature) {
3729 TempNewSymbol name_symbol = SymbolTable::probe(name_str, (int)name_len);
3730 if (name_symbol != NULL) {
3731 Method* method = the_class->lookup_method(name_symbol, signature);
3732 if (method != NULL) {
3733 // Even if prefixed, intermediate methods must exist.
3734 if (method->is_native()) {
3735 // Wahoo, we found a (possibly prefixed) version of the method, return it.
3736 return method;
3737 }
3738 if (depth < prefix_count) {
3739 // Try applying further prefixes (other than this one).
3740 method = search_prefix_name_space(depth+1, name_str, name_len, signature);
3741 if (method != NULL) {
3742 return method; // found
3743 }
3744
3745 // Try adding this prefix to the method name and see if it matches
3746 // another method name.
3747 char* prefix = prefixes[depth];
3748 size_t prefix_len = strlen(prefix);
3749 size_t trial_len = name_len + prefix_len;
3750 char* trial_name_str = NEW_RESOURCE_ARRAY(char, trial_len + 1);
3751 strcpy(trial_name_str, prefix);
3752 strcat(trial_name_str, name_str);
3753 method = search_prefix_name_space(depth+1, trial_name_str, trial_len,
3754 signature);
3755 if (method != NULL) {
3756 // If found along this branch, it was prefixed, mark as such
3757 method->set_is_prefixed_native();
3758 return method; // found
3759 }
3760 }
3761 }
3762 }
3763 return NULL; // This whole branch bore nothing
3764 }
3765
3766 // Return the method name with old prefixes stripped away.
3767 char* method_name_without_prefixes(Method* method) {
3768 Symbol* name = method->name();
3769 char* name_str = name->as_utf8();
3770
3771 // Old prefixing may be defunct, strip prefixes, if any.
3772 for (int i = prefix_count-1; i >= 0; i--) {
3773 char* prefix = prefixes[i];
3774 size_t prefix_len = strlen(prefix);
3775 if (strncmp(prefix, name_str, prefix_len) == 0) {
3776 name_str += prefix_len;
3777 }
3778 }
3779 return name_str;
3780 }
3781
3782 // Strip any prefixes off the old native method, then try to find a
3783 // (possibly prefixed) new native that matches it.
3784 Method* strip_and_search_for_new_native(Method* method) {
3785 ResourceMark rm;
3786 char* name_str = method_name_without_prefixes(method);
3787 return search_prefix_name_space(0, name_str, strlen(name_str),
3788 method->signature());
3789 }
3790
3791 public:
3792
3793 // Construct a native method transfer processor for this class.
3794 TransferNativeFunctionRegistration(InstanceKlass* _the_class) {
3795 assert(SafepointSynchronize::is_at_safepoint(), "sanity check");
3796
3797 the_class = _the_class;
3798 prefixes = JvmtiExport::get_all_native_method_prefixes(&prefix_count);
3799 }
3800
3801 // Attempt to transfer any of the old or deleted methods that are native
3802 void transfer_registrations(Method** old_methods, int methods_length) {
3803 for (int j = 0; j < methods_length; j++) {
3804 Method* old_method = old_methods[j];
3805
3806 if (old_method->is_native() && old_method->has_native_function()) {
3807 Method* new_method = strip_and_search_for_new_native(old_method);
3808 if (new_method != NULL) {
3809 // Actually set the native function in the new method.
3810 // Redefine does not send events (except CFLH), certainly not this
3811 // behind the scenes re-registration.
3812 new_method->set_native_function(old_method->native_function(),
3813 !Method::native_bind_event_is_interesting);
3814 }
3815 }
3816 }
3817 }
3818 };
3819
3820 // Don't lose the association between a native method and its JNI function.
3821 void VM_RedefineClasses::transfer_old_native_function_registrations(InstanceKlass* the_class) {
3822 TransferNativeFunctionRegistration transfer(the_class);
3823 transfer.transfer_registrations(_deleted_methods, _deleted_methods_length);
3824 transfer.transfer_registrations(_matching_old_methods, _matching_methods_length);
3825 }
3826
3827 // Deoptimize all compiled code that depends on this class.
3828 //
3829 // If the can_redefine_classes capability is obtained in the onload
3830 // phase then the compiler has recorded all dependencies from startup.
3831 // In that case we need only deoptimize and throw away all compiled code
3832 // that depends on the class.
3833 //
3834 // If can_redefine_classes is obtained sometime after the onload
3835 // phase then the dependency information may be incomplete. In that case
3836 // the first call to RedefineClasses causes all compiled code to be
3837 // thrown away. As can_redefine_classes has been obtained then
3838 // all future compilations will record dependencies so second and
3839 // subsequent calls to RedefineClasses need only throw away code
3840 // that depends on the class.
3841 //
3842 void VM_RedefineClasses::flush_dependent_code(InstanceKlass* ik, TRAPS) {
3843 assert_locked_or_safepoint(Compile_lock);
3844
3845 // All dependencies have been recorded from startup or this is a second or
3846 // subsequent use of RedefineClasses
3847 if (JvmtiExport::all_dependencies_are_recorded()) {
3848 CodeCache::flush_evol_dependents_on(ik);
3849 } else {
3850 CodeCache::mark_all_nmethods_for_deoptimization();
3851
3852 ResourceMark rm(THREAD);
3853 DeoptimizationMarker dm;
3854
3855 // Deoptimize all activations depending on marked nmethods
3856 Deoptimization::deoptimize_dependents();
3857
3858 // Make the dependent methods not entrant
3859 CodeCache::make_marked_nmethods_not_entrant();
3860
3861 // From now on we know that the dependency information is complete
3862 JvmtiExport::set_all_dependencies_are_recorded(true);
3863 }
3864 }
3865
3866 void VM_RedefineClasses::compute_added_deleted_matching_methods() {
3867 Method* old_method;
3868 Method* new_method;
3869
3870 _matching_old_methods = NEW_RESOURCE_ARRAY(Method*, _old_methods->length());
3871 _matching_new_methods = NEW_RESOURCE_ARRAY(Method*, _old_methods->length());
3872 _added_methods = NEW_RESOURCE_ARRAY(Method*, _new_methods->length());
3873 _deleted_methods = NEW_RESOURCE_ARRAY(Method*, _old_methods->length());
3874
3875 _matching_methods_length = 0;
3876 _deleted_methods_length = 0;
3877 _added_methods_length = 0;
3878
3879 int nj = 0;
3880 int oj = 0;
3881 while (true) {
3882 if (oj >= _old_methods->length()) {
3883 if (nj >= _new_methods->length()) {
3884 break; // we've looked at everything, done
3885 }
3886 // New method at the end
3887 new_method = _new_methods->at(nj);
3888 _added_methods[_added_methods_length++] = new_method;
3889 ++nj;
3890 } else if (nj >= _new_methods->length()) {
3891 // Old method, at the end, is deleted
3892 old_method = _old_methods->at(oj);
3893 _deleted_methods[_deleted_methods_length++] = old_method;
3894 ++oj;
3895 } else {
3896 old_method = _old_methods->at(oj);
3897 new_method = _new_methods->at(nj);
3898 if (old_method->name() == new_method->name()) {
3899 if (old_method->signature() == new_method->signature()) {
3900 _matching_old_methods[_matching_methods_length ] = old_method;
3901 _matching_new_methods[_matching_methods_length++] = new_method;
3902 ++nj;
3903 ++oj;
3904 } else {
3905 // added overloaded have already been moved to the end,
3906 // so this is a deleted overloaded method
3907 _deleted_methods[_deleted_methods_length++] = old_method;
3908 ++oj;
3909 }
3910 } else { // names don't match
3911 if (old_method->name()->fast_compare(new_method->name()) > 0) {
3912 // new method
3913 _added_methods[_added_methods_length++] = new_method;
3914 ++nj;
3915 } else {
3916 // deleted method
3917 _deleted_methods[_deleted_methods_length++] = old_method;
3918 ++oj;
3919 }
3920 }
3921 }
3922 }
3923 assert(_matching_methods_length + _deleted_methods_length == _old_methods->length(), "sanity");
3924 assert(_matching_methods_length + _added_methods_length == _new_methods->length(), "sanity");
3925 }
3926
3927
3928 void VM_RedefineClasses::swap_annotations(InstanceKlass* the_class,
3929 InstanceKlass* scratch_class) {
3930 // Swap annotation fields values
3931 Annotations* old_annotations = the_class->annotations();
3932 the_class->set_annotations(scratch_class->annotations());
3933 scratch_class->set_annotations(old_annotations);
3934 }
3935
3936
3937 // Install the redefinition of a class:
3938 // - house keeping (flushing breakpoints and caches, deoptimizing
3939 // dependent compiled code)
3940 // - replacing parts in the_class with parts from scratch_class
3941 // - adding a weak reference to track the obsolete but interesting
3942 // parts of the_class
3943 // - adjusting constant pool caches and vtables in other classes
3944 // that refer to methods in the_class. These adjustments use the
3945 // ClassLoaderDataGraph::classes_do() facility which only allows
3946 // a helper method to be specified. The interesting parameters
3947 // that we would like to pass to the helper method are saved in
3948 // static global fields in the VM operation.
3949 void VM_RedefineClasses::redefine_single_class(jclass the_jclass,
3950 InstanceKlass* scratch_class, TRAPS) {
3951
3952 HandleMark hm(THREAD); // make sure handles from this call are freed
3953
3954 if (log_is_enabled(Info, redefine, class, timer)) {
3955 _timer_rsc_phase1.start();
3956 }
3957
3958 InstanceKlass* the_class = get_ik(the_jclass);
3959
3960 // Remove all breakpoints in methods of this class
3961 JvmtiBreakpoints& jvmti_breakpoints = JvmtiCurrentBreakpoints::get_jvmti_breakpoints();
3962 jvmti_breakpoints.clearall_in_class_at_safepoint(the_class);
3963
3964 // Deoptimize all compiled code that depends on this class
3965 flush_dependent_code(the_class, THREAD);
3966
3967 _old_methods = the_class->methods();
3968 _new_methods = scratch_class->methods();
3969 _the_class = the_class;
3970 compute_added_deleted_matching_methods();
3971 update_jmethod_ids();
3972
3973 _any_class_has_resolved_methods = the_class->has_resolved_methods() || _any_class_has_resolved_methods;
3974
3975 // Attach new constant pool to the original klass. The original
3976 // klass still refers to the old constant pool (for now).
3977 scratch_class->constants()->set_pool_holder(the_class);
3978
3979 #if 0
3980 // In theory, with constant pool merging in place we should be able
3981 // to save space by using the new, merged constant pool in place of
3982 // the old constant pool(s). By "pool(s)" I mean the constant pool in
3983 // the klass version we are replacing now and any constant pool(s) in
3984 // previous versions of klass. Nice theory, doesn't work in practice.
3985 // When this code is enabled, even simple programs throw NullPointer
3986 // exceptions. I'm guessing that this is caused by some constant pool
3987 // cache difference between the new, merged constant pool and the
3988 // constant pool that was just being used by the klass. I'm keeping
3989 // this code around to archive the idea, but the code has to remain
3990 // disabled for now.
3991
3992 // Attach each old method to the new constant pool. This can be
3993 // done here since we are past the bytecode verification and
3994 // constant pool optimization phases.
3995 for (int i = _old_methods->length() - 1; i >= 0; i--) {
3996 Method* method = _old_methods->at(i);
3997 method->set_constants(scratch_class->constants());
3998 }
3999
4000 // NOTE: this doesn't work because you can redefine the same class in two
4001 // threads, each getting their own constant pool data appended to the
4002 // original constant pool. In order for the new methods to work when they
4003 // become old methods, they need to keep their updated copy of the constant pool.
4004
4005 {
4006 // walk all previous versions of the klass
4007 InstanceKlass *ik = the_class;
4008 PreviousVersionWalker pvw(ik);
4009 do {
4010 ik = pvw.next_previous_version();
4011 if (ik != NULL) {
4012
4013 // attach previous version of klass to the new constant pool
4014 ik->set_constants(scratch_class->constants());
4015
4016 // Attach each method in the previous version of klass to the
4017 // new constant pool
4018 Array<Method*>* prev_methods = ik->methods();
4019 for (int i = prev_methods->length() - 1; i >= 0; i--) {
4020 Method* method = prev_methods->at(i);
4021 method->set_constants(scratch_class->constants());
4022 }
4023 }
4024 } while (ik != NULL);
4025 }
4026 #endif
4027
4028 // Replace methods and constantpool
4029 the_class->set_methods(_new_methods);
4030 scratch_class->set_methods(_old_methods); // To prevent potential GCing of the old methods,
4031 // and to be able to undo operation easily.
4032
4033 Array<int>* old_ordering = the_class->method_ordering();
4034 the_class->set_method_ordering(scratch_class->method_ordering());
4035 scratch_class->set_method_ordering(old_ordering);
4036
4037 ConstantPool* old_constants = the_class->constants();
4038 the_class->set_constants(scratch_class->constants());
4039 scratch_class->set_constants(old_constants); // See the previous comment.
4040 #if 0
4041 // We are swapping the guts of "the new class" with the guts of "the
4042 // class". Since the old constant pool has just been attached to "the
4043 // new class", it seems logical to set the pool holder in the old
4044 // constant pool also. However, doing this will change the observable
4045 // class hierarchy for any old methods that are still executing. A
4046 // method can query the identity of its "holder" and this query uses
4047 // the method's constant pool link to find the holder. The change in
4048 // holding class from "the class" to "the new class" can confuse
4049 // things.
4050 //
4051 // Setting the old constant pool's holder will also cause
4052 // verification done during vtable initialization below to fail.
4053 // During vtable initialization, the vtable's class is verified to be
4054 // a subtype of the method's holder. The vtable's class is "the
4055 // class" and the method's holder is gotten from the constant pool
4056 // link in the method itself. For "the class"'s directly implemented
4057 // methods, the method holder is "the class" itself (as gotten from
4058 // the new constant pool). The check works fine in this case. The
4059 // check also works fine for methods inherited from super classes.
4060 //
4061 // Miranda methods are a little more complicated. A miranda method is
4062 // provided by an interface when the class implementing the interface
4063 // does not provide its own method. These interfaces are implemented
4064 // internally as an InstanceKlass. These special instanceKlasses
4065 // share the constant pool of the class that "implements" the
4066 // interface. By sharing the constant pool, the method holder of a
4067 // miranda method is the class that "implements" the interface. In a
4068 // non-redefine situation, the subtype check works fine. However, if
4069 // the old constant pool's pool holder is modified, then the check
4070 // fails because there is no class hierarchy relationship between the
4071 // vtable's class and "the new class".
4072
4073 old_constants->set_pool_holder(scratch_class());
4074 #endif
4075
4076 // track number of methods that are EMCP for add_previous_version() call below
4077 int emcp_method_count = check_methods_and_mark_as_obsolete();
4078 transfer_old_native_function_registrations(the_class);
4079
4080 // The class file bytes from before any retransformable agents mucked
4081 // with them was cached on the scratch class, move to the_class.
4082 // Note: we still want to do this if nothing needed caching since it
4083 // should get cleared in the_class too.
4084 if (the_class->get_cached_class_file() == 0) {
4085 // the_class doesn't have a cache yet so copy it
4086 the_class->set_cached_class_file(scratch_class->get_cached_class_file());
4087 }
4088 else if (scratch_class->get_cached_class_file() !=
4089 the_class->get_cached_class_file()) {
4090 // The same class can be present twice in the scratch classes list or there
4091 // are multiple concurrent RetransformClasses calls on different threads.
4092 // In such cases we have to deallocate scratch_class cached_class_file.
4093 os::free(scratch_class->get_cached_class_file());
4094 }
4095
4096 // NULL out in scratch class to not delete twice. The class to be redefined
4097 // always owns these bytes.
4098 scratch_class->set_cached_class_file(NULL);
4099
4100 // Replace inner_classes
4101 Array<u2>* old_inner_classes = the_class->inner_classes();
4102 the_class->set_inner_classes(scratch_class->inner_classes());
4103 scratch_class->set_inner_classes(old_inner_classes);
4104
4105 // Initialize the vtable and interface table after
4106 // methods have been rewritten
4107 {
4108 ResourceMark rm(THREAD);
4109 // no exception should happen here since we explicitly
4110 // do not check loader constraints.
4111 // compare_and_normalize_class_versions has already checked:
4112 // - classloaders unchanged, signatures unchanged
4113 // - all instanceKlasses for redefined classes reused & contents updated
4114 the_class->vtable().initialize_vtable(false, THREAD);
4115 the_class->itable().initialize_itable(false, THREAD);
4116 assert(!HAS_PENDING_EXCEPTION || (THREAD->pending_exception()->is_a(SystemDictionary::ThreadDeath_klass())), "redefine exception");
4117 }
4118
4119 // Leave arrays of jmethodIDs and itable index cache unchanged
4120
4121 // Copy the "source file name" attribute from new class version
4122 the_class->set_source_file_name_index(
4123 scratch_class->source_file_name_index());
4124
4125 // Copy the "source debug extension" attribute from new class version
4126 the_class->set_source_debug_extension(
4127 scratch_class->source_debug_extension(),
4128 scratch_class->source_debug_extension() == NULL ? 0 :
4129 (int)strlen(scratch_class->source_debug_extension()));
4130
4131 // Use of javac -g could be different in the old and the new
4132 if (scratch_class->access_flags().has_localvariable_table() !=
4133 the_class->access_flags().has_localvariable_table()) {
4134
4135 AccessFlags flags = the_class->access_flags();
4136 if (scratch_class->access_flags().has_localvariable_table()) {
4137 flags.set_has_localvariable_table();
4138 } else {
4139 flags.clear_has_localvariable_table();
4140 }
4141 the_class->set_access_flags(flags);
4142 }
4143
4144 swap_annotations(the_class, scratch_class);
4145
4146 // Replace minor version number of class file
4147 u2 old_minor_version = the_class->minor_version();
4148 the_class->set_minor_version(scratch_class->minor_version());
4149 scratch_class->set_minor_version(old_minor_version);
4150
4151 // Replace major version number of class file
4152 u2 old_major_version = the_class->major_version();
4153 the_class->set_major_version(scratch_class->major_version());
4154 scratch_class->set_major_version(old_major_version);
4155
4156 // Replace CP indexes for class and name+type of enclosing method
4157 u2 old_class_idx = the_class->enclosing_method_class_index();
4158 u2 old_method_idx = the_class->enclosing_method_method_index();
4159 the_class->set_enclosing_method_indices(
4160 scratch_class->enclosing_method_class_index(),
4161 scratch_class->enclosing_method_method_index());
4162 scratch_class->set_enclosing_method_indices(old_class_idx, old_method_idx);
4163
4164 // Replace fingerprint data
4165 the_class->set_has_passed_fingerprint_check(scratch_class->has_passed_fingerprint_check());
4166 the_class->store_fingerprint(scratch_class->get_stored_fingerprint());
4167
4168 the_class->set_has_been_redefined();
4169
4170 if (!the_class->should_be_initialized()) {
4171 // Class was already initialized, so AOT has only seen the original version.
4172 // We need to let AOT look at it again.
4173 AOTLoader::load_for_klass(the_class, THREAD);
4174 }
4175
4176 // keep track of previous versions of this class
4177 the_class->add_previous_version(scratch_class, emcp_method_count);
4178
4179 _timer_rsc_phase1.stop();
4180 if (log_is_enabled(Info, redefine, class, timer)) {
4181 _timer_rsc_phase2.start();
4182 }
4183
4184 // Adjust constantpool caches and vtables for all classes
4185 // that reference methods of the evolved class.
4186 AdjustCpoolCacheAndVtable adjust_cpool_cache_and_vtable(THREAD);
4187 ClassLoaderDataGraph::classes_do(&adjust_cpool_cache_and_vtable);
4188
4189 if (the_class->oop_map_cache() != NULL) {
4190 // Flush references to any obsolete methods from the oop map cache
4191 // so that obsolete methods are not pinned.
4192 the_class->oop_map_cache()->flush_obsolete_entries();
4193 }
4194
4195 increment_class_counter((InstanceKlass *)the_class, THREAD);
4196 {
4197 ResourceMark rm(THREAD);
4198 // increment the classRedefinedCount field in the_class and in any
4199 // direct and indirect subclasses of the_class
4200 log_info(redefine, class, load)
4201 ("redefined name=%s, count=%d (avail_mem=" UINT64_FORMAT "K)",
4202 the_class->external_name(), java_lang_Class::classRedefinedCount(the_class->java_mirror()), os::available_memory() >> 10);
4203 Events::log_redefinition(THREAD, "redefined class name=%s, count=%d",
4204 the_class->external_name(),
4205 java_lang_Class::classRedefinedCount(the_class->java_mirror()));
4206
4207 }
4208 _timer_rsc_phase2.stop();
4209 } // end redefine_single_class()
4210
4211
4212 // Increment the classRedefinedCount field in the specific InstanceKlass
4213 // and in all direct and indirect subclasses.
4214 void VM_RedefineClasses::increment_class_counter(InstanceKlass *ik, TRAPS) {
4215 oop class_mirror = ik->java_mirror();
4216 Klass* class_oop = java_lang_Class::as_Klass(class_mirror);
4217 int new_count = java_lang_Class::classRedefinedCount(class_mirror) + 1;
4218 java_lang_Class::set_classRedefinedCount(class_mirror, new_count);
4219
4220 if (class_oop != _the_class) {
4221 // _the_class count is printed at end of redefine_single_class()
4222 log_debug(redefine, class, subclass)("updated count in subclass=%s to %d", ik->external_name(), new_count);
4223 }
4224
4225 for (Klass *subk = ik->subklass(); subk != NULL;
4226 subk = subk->next_sibling()) {
4227 if (subk->is_instance_klass()) {
4228 // Only update instanceKlasses
4229 InstanceKlass *subik = InstanceKlass::cast(subk);
4230 // recursively do subclasses of the current subclass
4231 increment_class_counter(subik, THREAD);
4232 }
4233 }
4234 }
4235
4236 void VM_RedefineClasses::CheckClass::do_klass(Klass* k) {
4237 bool no_old_methods = true; // be optimistic
4238
4239 // Both array and instance classes have vtables.
4240 // a vtable should never contain old or obsolete methods
4241 ResourceMark rm(_thread);
4242 if (k->vtable_length() > 0 &&
4243 !k->vtable().check_no_old_or_obsolete_entries()) {
4244 if (log_is_enabled(Trace, redefine, class, obsolete, metadata)) {
4245 log_trace(redefine, class, obsolete, metadata)
4246 ("klassVtable::check_no_old_or_obsolete_entries failure -- OLD or OBSOLETE method found -- class: %s",
4247 k->signature_name());
4248 k->vtable().dump_vtable();
4249 }
4250 no_old_methods = false;
4251 }
4252
4253 if (k->is_instance_klass()) {
4254 HandleMark hm(_thread);
4255 InstanceKlass *ik = InstanceKlass::cast(k);
4256
4257 // an itable should never contain old or obsolete methods
4258 if (ik->itable_length() > 0 &&
4259 !ik->itable().check_no_old_or_obsolete_entries()) {
4260 if (log_is_enabled(Trace, redefine, class, obsolete, metadata)) {
4261 log_trace(redefine, class, obsolete, metadata)
4262 ("klassItable::check_no_old_or_obsolete_entries failure -- OLD or OBSOLETE method found -- class: %s",
4263 ik->signature_name());
4264 ik->itable().dump_itable();
4265 }
4266 no_old_methods = false;
4267 }
4268
4269 // the constant pool cache should never contain non-deleted old or obsolete methods
4270 if (ik->constants() != NULL &&
4271 ik->constants()->cache() != NULL &&
4272 !ik->constants()->cache()->check_no_old_or_obsolete_entries()) {
4273 if (log_is_enabled(Trace, redefine, class, obsolete, metadata)) {
4274 log_trace(redefine, class, obsolete, metadata)
4275 ("cp-cache::check_no_old_or_obsolete_entries failure -- OLD or OBSOLETE method found -- class: %s",
4276 ik->signature_name());
4277 ik->constants()->cache()->dump_cache();
4278 }
4279 no_old_methods = false;
4280 }
4281 }
4282
4283 // print and fail guarantee if old methods are found.
4284 if (!no_old_methods) {
4285 if (log_is_enabled(Trace, redefine, class, obsolete, metadata)) {
4286 dump_methods();
4287 } else {
4288 log_trace(redefine, class)("Use the '-Xlog:redefine+class*:' option "
4289 "to see more info about the following guarantee() failure.");
4290 }
4291 guarantee(false, "OLD and/or OBSOLETE method(s) found");
4292 }
4293 }
4294
4295
4296 void VM_RedefineClasses::dump_methods() {
4297 int j;
4298 log_trace(redefine, class, dump)("_old_methods --");
4299 for (j = 0; j < _old_methods->length(); ++j) {
4300 LogStreamHandle(Trace, redefine, class, dump) log_stream;
4301 Method* m = _old_methods->at(j);
4302 log_stream.print("%4d (%5d) ", j, m->vtable_index());
4303 m->access_flags().print_on(&log_stream);
4304 log_stream.print(" -- ");
4305 m->print_name(&log_stream);
4306 log_stream.cr();
4307 }
4308 log_trace(redefine, class, dump)("_new_methods --");
4309 for (j = 0; j < _new_methods->length(); ++j) {
4310 LogStreamHandle(Trace, redefine, class, dump) log_stream;
4311 Method* m = _new_methods->at(j);
4312 log_stream.print("%4d (%5d) ", j, m->vtable_index());
4313 m->access_flags().print_on(&log_stream);
4314 log_stream.print(" -- ");
4315 m->print_name(&log_stream);
4316 log_stream.cr();
4317 }
4318 log_trace(redefine, class, dump)("_matching_methods --");
4319 for (j = 0; j < _matching_methods_length; ++j) {
4320 LogStreamHandle(Trace, redefine, class, dump) log_stream;
4321 Method* m = _matching_old_methods[j];
4322 log_stream.print("%4d (%5d) ", j, m->vtable_index());
4323 m->access_flags().print_on(&log_stream);
4324 log_stream.print(" -- ");
4325 m->print_name();
4326 log_stream.cr();
4327
4328 m = _matching_new_methods[j];
4329 log_stream.print(" (%5d) ", m->vtable_index());
4330 m->access_flags().print_on(&log_stream);
4331 log_stream.cr();
4332 }
4333 log_trace(redefine, class, dump)("_deleted_methods --");
4334 for (j = 0; j < _deleted_methods_length; ++j) {
4335 LogStreamHandle(Trace, redefine, class, dump) log_stream;
4336 Method* m = _deleted_methods[j];
4337 log_stream.print("%4d (%5d) ", j, m->vtable_index());
4338 m->access_flags().print_on(&log_stream);
4339 log_stream.print(" -- ");
4340 m->print_name(&log_stream);
4341 log_stream.cr();
4342 }
4343 log_trace(redefine, class, dump)("_added_methods --");
4344 for (j = 0; j < _added_methods_length; ++j) {
4345 LogStreamHandle(Trace, redefine, class, dump) log_stream;
4346 Method* m = _added_methods[j];
4347 log_stream.print("%4d (%5d) ", j, m->vtable_index());
4348 m->access_flags().print_on(&log_stream);
4349 log_stream.print(" -- ");
4350 m->print_name(&log_stream);
4351 log_stream.cr();
4352 }
4353 }
4354
4355 void VM_RedefineClasses::print_on_error(outputStream* st) const {
4356 VM_Operation::print_on_error(st);
4357 if (_the_class != NULL) {
4358 ResourceMark rm;
4359 st->print_cr(", redefining class %s", _the_class->external_name());
4360 }
4361 }