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