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