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