1 /*
2 * Copyright (c) 2003, 2020, 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 "jfr/jfrEvents.hpp"
39 #include "logging/logStream.hpp"
40 #include "memory/metadataFactory.hpp"
41 #include "memory/metaspaceShared.hpp"
42 #include "memory/resourceArea.hpp"
43 #include "memory/universe.hpp"
44 #include "oops/annotations.hpp"
45 #include "oops/constantPool.hpp"
46 #include "oops/fieldStreams.inline.hpp"
47 #include "oops/klassVtable.hpp"
48 #include "oops/oop.inline.hpp"
49 #include "oops/recordComponent.hpp"
50 #include "prims/jvmtiImpl.hpp"
51 #include "prims/jvmtiRedefineClasses.hpp"
52 #include "prims/jvmtiThreadState.inline.hpp"
53 #include "prims/resolvedMethodTable.hpp"
54 #include "prims/methodComparator.hpp"
55 #include "runtime/atomic.hpp"
56 #include "runtime/deoptimization.hpp"
57 #include "runtime/handles.inline.hpp"
58 #include "runtime/jniHandles.inline.hpp"
59 #include "runtime/relocator.hpp"
60 #include "runtime/safepointVerifiers.hpp"
61 #include "utilities/bitMap.inline.hpp"
62 #include "utilities/events.hpp"
63
64 Array<Method*>* VM_RedefineClasses::_old_methods = NULL;
65 Array<Method*>* VM_RedefineClasses::_new_methods = NULL;
66 Method** VM_RedefineClasses::_matching_old_methods = NULL;
67 Method** VM_RedefineClasses::_matching_new_methods = NULL;
68 Method** VM_RedefineClasses::_deleted_methods = NULL;
69 Method** VM_RedefineClasses::_added_methods = NULL;
70 int VM_RedefineClasses::_matching_methods_length = 0;
71 int VM_RedefineClasses::_deleted_methods_length = 0;
72 int VM_RedefineClasses::_added_methods_length = 0;
73 bool VM_RedefineClasses::_has_redefined_Object = false;
74 bool VM_RedefineClasses::_has_null_class_loader = false;
75 u8 VM_RedefineClasses::_id_counter = 0;
76
77 VM_RedefineClasses::VM_RedefineClasses(jint class_count,
78 const jvmtiClassDefinition *class_defs,
79 JvmtiClassLoadKind class_load_kind) {
80 _class_count = class_count;
81 _class_defs = class_defs;
82 _class_load_kind = class_load_kind;
83 _any_class_has_resolved_methods = false;
84 _res = JVMTI_ERROR_NONE;
85 _the_class = NULL;
86 _has_redefined_Object = false;
87 _has_null_class_loader = false;
88 _id = next_id();
89 }
90
91 static inline InstanceKlass* get_ik(jclass def) {
92 oop mirror = JNIHandles::resolve_non_null(def);
93 return InstanceKlass::cast(java_lang_Class::as_Klass(mirror));
94 }
95
96 // If any of the classes are being redefined, wait
97 // Parallel constant pool merging leads to indeterminate constant pools.
98 void VM_RedefineClasses::lock_classes() {
99 MonitorLocker ml(RedefineClasses_lock);
100 bool has_redefined;
101 do {
102 has_redefined = false;
103 // Go through classes each time until none are being redefined.
104 for (int i = 0; i < _class_count; i++) {
105 if (get_ik(_class_defs[i].klass)->is_being_redefined()) {
106 ml.wait();
107 has_redefined = true;
108 break; // for loop
109 }
110 }
111 } while (has_redefined);
112 for (int i = 0; i < _class_count; i++) {
113 get_ik(_class_defs[i].klass)->set_is_being_redefined(true);
114 }
115 ml.notify_all();
116 }
117
118 void VM_RedefineClasses::unlock_classes() {
119 MonitorLocker ml(RedefineClasses_lock);
120 for (int i = 0; i < _class_count; i++) {
121 assert(get_ik(_class_defs[i].klass)->is_being_redefined(),
122 "should be being redefined to get here");
123 get_ik(_class_defs[i].klass)->set_is_being_redefined(false);
124 }
125 ml.notify_all();
126 }
127
128 bool VM_RedefineClasses::doit_prologue() {
129 if (_class_count == 0) {
130 _res = JVMTI_ERROR_NONE;
131 return false;
132 }
133 if (_class_defs == NULL) {
134 _res = JVMTI_ERROR_NULL_POINTER;
135 return false;
136 }
137
138 for (int i = 0; i < _class_count; i++) {
139 if (_class_defs[i].klass == NULL) {
140 _res = JVMTI_ERROR_INVALID_CLASS;
141 return false;
142 }
143 if (_class_defs[i].class_byte_count == 0) {
144 _res = JVMTI_ERROR_INVALID_CLASS_FORMAT;
145 return false;
146 }
147 if (_class_defs[i].class_bytes == NULL) {
148 _res = JVMTI_ERROR_NULL_POINTER;
149 return false;
150 }
151
152 oop mirror = JNIHandles::resolve_non_null(_class_defs[i].klass);
153 // classes for primitives, arrays, hidden and vm unsafe anonymous classes
154 // cannot be redefined.
155 if (!is_modifiable_class(mirror)) {
156 _res = JVMTI_ERROR_UNMODIFIABLE_CLASS;
157 return false;
158 }
159 }
160
161 // Start timer after all the sanity checks; not quite accurate, but
162 // better than adding a bunch of stop() calls.
163 if (log_is_enabled(Info, redefine, class, timer)) {
164 _timer_vm_op_prologue.start();
165 }
166
167 lock_classes();
168 // We first load new class versions in the prologue, because somewhere down the
169 // call chain it is required that the current thread is a Java thread.
170 _res = load_new_class_versions(Thread::current());
171 if (_res != JVMTI_ERROR_NONE) {
172 // free any successfully created classes, since none are redefined
173 for (int i = 0; i < _class_count; i++) {
174 if (_scratch_classes[i] != NULL) {
175 ClassLoaderData* cld = _scratch_classes[i]->class_loader_data();
176 // Free the memory for this class at class unloading time. Not before
177 // because CMS might think this is still live.
178 InstanceKlass* ik = get_ik(_class_defs[i].klass);
179 if (ik->get_cached_class_file() == _scratch_classes[i]->get_cached_class_file()) {
180 // Don't double-free cached_class_file copied from the original class if error.
181 _scratch_classes[i]->set_cached_class_file(NULL);
182 }
183 cld->add_to_deallocate_list(InstanceKlass::cast(_scratch_classes[i]));
184 }
185 }
186 // Free os::malloc allocated memory in load_new_class_version.
187 os::free(_scratch_classes);
188 _timer_vm_op_prologue.stop();
189 unlock_classes();
190 return false;
191 }
192
193 _timer_vm_op_prologue.stop();
194 return true;
195 }
196
197 void VM_RedefineClasses::doit() {
198 Thread *thread = Thread::current();
199
200 #if INCLUDE_CDS
201 if (UseSharedSpaces) {
202 // Sharing is enabled so we remap the shared readonly space to
203 // shared readwrite, private just in case we need to redefine
204 // a shared class. We do the remap during the doit() phase of
205 // the safepoint to be safer.
206 if (!MetaspaceShared::remap_shared_readonly_as_readwrite()) {
207 log_info(redefine, class, load)("failed to remap shared readonly space to readwrite, private");
208 _res = JVMTI_ERROR_INTERNAL;
209 return;
210 }
211 }
212 #endif
213
214 // Mark methods seen on stack and everywhere else so old methods are not
215 // cleaned up if they're on the stack.
216 MetadataOnStackMark md_on_stack(/*walk_all_metadata*/true, /*redefinition_walk*/true);
217 HandleMark hm(thread); // make sure any handles created are deleted
218 // before the stack walk again.
219
220 for (int i = 0; i < _class_count; i++) {
221 redefine_single_class(_class_defs[i].klass, _scratch_classes[i], thread);
222 }
223
224 // Flush all compiled code that depends on the classes redefined.
225 flush_dependent_code();
226
227 // Adjust constantpool caches and vtables for all classes
228 // that reference methods of the evolved classes.
229 // Have to do this after all classes are redefined and all methods that
230 // are redefined are marked as old.
231 AdjustAndCleanMetadata adjust_and_clean_metadata(thread);
232 ClassLoaderDataGraph::classes_do(&adjust_and_clean_metadata);
233
234 // JSR-292 support
235 if (_any_class_has_resolved_methods) {
236 bool trace_name_printed = false;
237 ResolvedMethodTable::adjust_method_entries(&trace_name_printed);
238 }
239
240 // Increment flag indicating that some invariants are no longer true.
241 // See jvmtiExport.hpp for detailed explanation.
242 JvmtiExport::increment_redefinition_count();
243
244 // check_class() is optionally called for product bits, but is
245 // always called for non-product bits.
246 #ifdef PRODUCT
247 if (log_is_enabled(Trace, redefine, class, obsolete, metadata)) {
248 #endif
249 log_trace(redefine, class, obsolete, metadata)("calling check_class");
250 CheckClass check_class(thread);
251 ClassLoaderDataGraph::classes_do(&check_class);
252 #ifdef PRODUCT
253 }
254 #endif
255
256 // Clean up any metadata now unreferenced while MetadataOnStackMark is set.
257 ClassLoaderDataGraph::clean_deallocate_lists(false);
258 }
259
260 void VM_RedefineClasses::doit_epilogue() {
261 unlock_classes();
262
263 // Free os::malloc allocated memory.
264 os::free(_scratch_classes);
265
266 // Reset the_class to null for error printing.
267 _the_class = NULL;
268
269 if (log_is_enabled(Info, redefine, class, timer)) {
270 // Used to have separate timers for "doit" and "all", but the timer
271 // overhead skewed the measurements.
272 julong doit_time = _timer_rsc_phase1.milliseconds() +
273 _timer_rsc_phase2.milliseconds();
274 julong all_time = _timer_vm_op_prologue.milliseconds() + doit_time;
275
276 log_info(redefine, class, timer)
277 ("vm_op: all=" JULONG_FORMAT " prologue=" JULONG_FORMAT " doit=" JULONG_FORMAT,
278 all_time, (julong)_timer_vm_op_prologue.milliseconds(), doit_time);
279 log_info(redefine, class, timer)
280 ("redefine_single_class: phase1=" JULONG_FORMAT " phase2=" JULONG_FORMAT,
281 (julong)_timer_rsc_phase1.milliseconds(), (julong)_timer_rsc_phase2.milliseconds());
282 }
283 }
284
285 bool VM_RedefineClasses::is_modifiable_class(oop klass_mirror) {
286 // classes for primitives cannot be redefined
287 if (java_lang_Class::is_primitive(klass_mirror)) {
288 return false;
289 }
290 Klass* k = java_lang_Class::as_Klass(klass_mirror);
291 // classes for arrays cannot be redefined
292 if (k == NULL || !k->is_instance_klass()) {
293 return false;
294 }
295
296 // Cannot redefine or retransform a hidden or an unsafe anonymous class.
297 if (InstanceKlass::cast(k)->is_hidden() ||
298 InstanceKlass::cast(k)->is_unsafe_anonymous()) {
299 return false;
300 }
301 return true;
302 }
303
304 // Append the current entry at scratch_i in scratch_cp to *merge_cp_p
305 // where the end of *merge_cp_p is specified by *merge_cp_length_p. For
306 // direct CP entries, there is just the current entry to append. For
307 // indirect and double-indirect CP entries, there are zero or more
308 // referenced CP entries along with the current entry to append.
309 // Indirect and double-indirect CP entries are handled by recursive
310 // calls to append_entry() as needed. The referenced CP entries are
311 // always appended to *merge_cp_p before the referee CP entry. These
312 // referenced CP entries may already exist in *merge_cp_p in which case
313 // there is nothing extra to append and only the current entry is
314 // appended.
315 void VM_RedefineClasses::append_entry(const constantPoolHandle& scratch_cp,
316 int scratch_i, constantPoolHandle *merge_cp_p, int *merge_cp_length_p,
317 TRAPS) {
318
319 // append is different depending on entry tag type
320 switch (scratch_cp->tag_at(scratch_i).value()) {
321
322 // The old verifier is implemented outside the VM. It loads classes,
323 // but does not resolve constant pool entries directly so we never
324 // see Class entries here with the old verifier. Similarly the old
325 // verifier does not like Class entries in the input constant pool.
326 // The split-verifier is implemented in the VM so it can optionally
327 // and directly resolve constant pool entries to load classes. The
328 // split-verifier can accept either Class entries or UnresolvedClass
329 // entries in the input constant pool. We revert the appended copy
330 // back to UnresolvedClass so that either verifier will be happy
331 // with the constant pool entry.
332 //
333 // this is an indirect CP entry so it needs special handling
334 case JVM_CONSTANT_Class:
335 case JVM_CONSTANT_UnresolvedClass:
336 {
337 int name_i = scratch_cp->klass_name_index_at(scratch_i);
338 int new_name_i = find_or_append_indirect_entry(scratch_cp, name_i, merge_cp_p,
339 merge_cp_length_p, THREAD);
340
341 if (new_name_i != name_i) {
342 log_trace(redefine, class, constantpool)
343 ("Class entry@%d name_index change: %d to %d",
344 *merge_cp_length_p, name_i, new_name_i);
345 }
346
347 (*merge_cp_p)->temp_unresolved_klass_at_put(*merge_cp_length_p, new_name_i);
348 if (scratch_i != *merge_cp_length_p) {
349 // The new entry in *merge_cp_p is at a different index than
350 // the new entry in scratch_cp so we need to map the index values.
351 map_index(scratch_cp, scratch_i, *merge_cp_length_p);
352 }
353 (*merge_cp_length_p)++;
354 } break;
355
356 // these are direct CP entries so they can be directly appended,
357 // but double and long take two constant pool entries
358 case JVM_CONSTANT_Double: // fall through
359 case JVM_CONSTANT_Long:
360 {
361 ConstantPool::copy_entry_to(scratch_cp, scratch_i, *merge_cp_p, *merge_cp_length_p,
362 THREAD);
363
364 if (scratch_i != *merge_cp_length_p) {
365 // The new entry in *merge_cp_p is at a different index than
366 // the new entry in scratch_cp so we need to map the index values.
367 map_index(scratch_cp, scratch_i, *merge_cp_length_p);
368 }
369 (*merge_cp_length_p) += 2;
370 } break;
371
372 // these are direct CP entries so they can be directly appended
373 case JVM_CONSTANT_Float: // fall through
374 case JVM_CONSTANT_Integer: // fall through
375 case JVM_CONSTANT_Utf8: // fall through
376
377 // This was an indirect CP entry, but it has been changed into
378 // Symbol*s so this entry can be directly appended.
379 case JVM_CONSTANT_String: // fall through
380 {
381 ConstantPool::copy_entry_to(scratch_cp, scratch_i, *merge_cp_p, *merge_cp_length_p,
382 THREAD);
383
384 if (scratch_i != *merge_cp_length_p) {
385 // The new entry in *merge_cp_p is at a different index than
386 // the new entry in scratch_cp so we need to map the index values.
387 map_index(scratch_cp, scratch_i, *merge_cp_length_p);
388 }
389 (*merge_cp_length_p)++;
390 } break;
391
392 // this is an indirect CP entry so it needs special handling
393 case JVM_CONSTANT_NameAndType:
394 {
395 int name_ref_i = scratch_cp->name_ref_index_at(scratch_i);
396 int new_name_ref_i = find_or_append_indirect_entry(scratch_cp, name_ref_i, merge_cp_p,
397 merge_cp_length_p, THREAD);
398
399 int signature_ref_i = scratch_cp->signature_ref_index_at(scratch_i);
400 int new_signature_ref_i = find_or_append_indirect_entry(scratch_cp, signature_ref_i,
401 merge_cp_p, merge_cp_length_p,
402 THREAD);
403
404 // If the referenced entries already exist in *merge_cp_p, then
405 // both new_name_ref_i and new_signature_ref_i will both be 0.
406 // In that case, all we are appending is the current entry.
407 if (new_name_ref_i != name_ref_i) {
408 log_trace(redefine, class, constantpool)
409 ("NameAndType entry@%d name_ref_index change: %d to %d",
410 *merge_cp_length_p, name_ref_i, new_name_ref_i);
411 }
412 if (new_signature_ref_i != signature_ref_i) {
413 log_trace(redefine, class, constantpool)
414 ("NameAndType entry@%d signature_ref_index change: %d to %d",
415 *merge_cp_length_p, signature_ref_i, new_signature_ref_i);
416 }
417
418 (*merge_cp_p)->name_and_type_at_put(*merge_cp_length_p,
419 new_name_ref_i, new_signature_ref_i);
420 if (scratch_i != *merge_cp_length_p) {
421 // The new entry in *merge_cp_p is at a different index than
422 // the new entry in scratch_cp so we need to map the index values.
423 map_index(scratch_cp, scratch_i, *merge_cp_length_p);
424 }
425 (*merge_cp_length_p)++;
426 } break;
427
428 // this is a double-indirect CP entry so it needs special handling
429 case JVM_CONSTANT_Fieldref: // fall through
430 case JVM_CONSTANT_InterfaceMethodref: // fall through
431 case JVM_CONSTANT_Methodref:
432 {
433 int klass_ref_i = scratch_cp->uncached_klass_ref_index_at(scratch_i);
434 int new_klass_ref_i = find_or_append_indirect_entry(scratch_cp, klass_ref_i,
435 merge_cp_p, merge_cp_length_p, THREAD);
436
437 int name_and_type_ref_i = scratch_cp->uncached_name_and_type_ref_index_at(scratch_i);
438 int new_name_and_type_ref_i = find_or_append_indirect_entry(scratch_cp, name_and_type_ref_i,
439 merge_cp_p, merge_cp_length_p, THREAD);
440
441 const char *entry_name = NULL;
442 switch (scratch_cp->tag_at(scratch_i).value()) {
443 case JVM_CONSTANT_Fieldref:
444 entry_name = "Fieldref";
445 (*merge_cp_p)->field_at_put(*merge_cp_length_p, new_klass_ref_i,
446 new_name_and_type_ref_i);
447 break;
448 case JVM_CONSTANT_InterfaceMethodref:
449 entry_name = "IFMethodref";
450 (*merge_cp_p)->interface_method_at_put(*merge_cp_length_p,
451 new_klass_ref_i, new_name_and_type_ref_i);
452 break;
453 case JVM_CONSTANT_Methodref:
454 entry_name = "Methodref";
455 (*merge_cp_p)->method_at_put(*merge_cp_length_p, new_klass_ref_i,
456 new_name_and_type_ref_i);
457 break;
458 default:
459 guarantee(false, "bad switch");
460 break;
461 }
462
463 if (klass_ref_i != new_klass_ref_i) {
464 log_trace(redefine, class, constantpool)
465 ("%s entry@%d class_index changed: %d to %d", entry_name, *merge_cp_length_p, klass_ref_i, new_klass_ref_i);
466 }
467 if (name_and_type_ref_i != new_name_and_type_ref_i) {
468 log_trace(redefine, class, constantpool)
469 ("%s entry@%d name_and_type_index changed: %d to %d",
470 entry_name, *merge_cp_length_p, name_and_type_ref_i, new_name_and_type_ref_i);
471 }
472
473 if (scratch_i != *merge_cp_length_p) {
474 // The new entry in *merge_cp_p is at a different index than
475 // the new entry in scratch_cp so we need to map the index values.
476 map_index(scratch_cp, scratch_i, *merge_cp_length_p);
477 }
478 (*merge_cp_length_p)++;
479 } break;
480
481 // this is an indirect CP entry so it needs special handling
482 case JVM_CONSTANT_MethodType:
483 {
484 int ref_i = scratch_cp->method_type_index_at(scratch_i);
485 int new_ref_i = find_or_append_indirect_entry(scratch_cp, ref_i, merge_cp_p,
486 merge_cp_length_p, THREAD);
487 if (new_ref_i != ref_i) {
488 log_trace(redefine, class, constantpool)
489 ("MethodType entry@%d ref_index change: %d to %d", *merge_cp_length_p, ref_i, new_ref_i);
490 }
491 (*merge_cp_p)->method_type_index_at_put(*merge_cp_length_p, new_ref_i);
492 if (scratch_i != *merge_cp_length_p) {
493 // The new entry in *merge_cp_p is at a different index than
494 // the new entry in scratch_cp so we need to map the index values.
495 map_index(scratch_cp, scratch_i, *merge_cp_length_p);
496 }
497 (*merge_cp_length_p)++;
498 } break;
499
500 // this is an indirect CP entry so it needs special handling
501 case JVM_CONSTANT_MethodHandle:
502 {
503 int ref_kind = scratch_cp->method_handle_ref_kind_at(scratch_i);
504 int ref_i = scratch_cp->method_handle_index_at(scratch_i);
505 int new_ref_i = find_or_append_indirect_entry(scratch_cp, ref_i, merge_cp_p,
506 merge_cp_length_p, THREAD);
507 if (new_ref_i != ref_i) {
508 log_trace(redefine, class, constantpool)
509 ("MethodHandle entry@%d ref_index change: %d to %d", *merge_cp_length_p, ref_i, new_ref_i);
510 }
511 (*merge_cp_p)->method_handle_index_at_put(*merge_cp_length_p, ref_kind, new_ref_i);
512 if (scratch_i != *merge_cp_length_p) {
513 // The new entry in *merge_cp_p is at a different index than
514 // the new entry in scratch_cp so we need to map the index values.
515 map_index(scratch_cp, scratch_i, *merge_cp_length_p);
516 }
517 (*merge_cp_length_p)++;
518 } break;
519
520 // this is an indirect CP entry so it needs special handling
521 case JVM_CONSTANT_Dynamic: // fall through
522 case JVM_CONSTANT_InvokeDynamic:
523 {
524 // Index of the bootstrap specifier in the operands array
525 int old_bs_i = scratch_cp->bootstrap_methods_attribute_index(scratch_i);
526 int new_bs_i = find_or_append_operand(scratch_cp, old_bs_i, merge_cp_p,
527 merge_cp_length_p, THREAD);
528 // The bootstrap method NameAndType_info index
529 int old_ref_i = scratch_cp->bootstrap_name_and_type_ref_index_at(scratch_i);
530 int new_ref_i = find_or_append_indirect_entry(scratch_cp, old_ref_i, merge_cp_p,
531 merge_cp_length_p, THREAD);
532 if (new_bs_i != old_bs_i) {
533 log_trace(redefine, class, constantpool)
534 ("Dynamic entry@%d bootstrap_method_attr_index change: %d to %d",
535 *merge_cp_length_p, old_bs_i, new_bs_i);
536 }
537 if (new_ref_i != old_ref_i) {
538 log_trace(redefine, class, constantpool)
539 ("Dynamic entry@%d name_and_type_index change: %d to %d", *merge_cp_length_p, old_ref_i, new_ref_i);
540 }
541
542 if (scratch_cp->tag_at(scratch_i).is_dynamic_constant())
543 (*merge_cp_p)->dynamic_constant_at_put(*merge_cp_length_p, new_bs_i, new_ref_i);
544 else
545 (*merge_cp_p)->invoke_dynamic_at_put(*merge_cp_length_p, new_bs_i, new_ref_i);
546 if (scratch_i != *merge_cp_length_p) {
547 // The new entry in *merge_cp_p is at a different index than
548 // the new entry in scratch_cp so we need to map the index values.
549 map_index(scratch_cp, scratch_i, *merge_cp_length_p);
550 }
551 (*merge_cp_length_p)++;
552 } break;
553
554 // At this stage, Class or UnresolvedClass could be in scratch_cp, but not
555 // ClassIndex
556 case JVM_CONSTANT_ClassIndex: // fall through
557
558 // Invalid is used as the tag for the second constant pool entry
559 // occupied by JVM_CONSTANT_Double or JVM_CONSTANT_Long. It should
560 // not be seen by itself.
561 case JVM_CONSTANT_Invalid: // fall through
562
563 // At this stage, String could be here, but not StringIndex
564 case JVM_CONSTANT_StringIndex: // fall through
565
566 // At this stage JVM_CONSTANT_UnresolvedClassInError should not be
567 // here
568 case JVM_CONSTANT_UnresolvedClassInError: // fall through
569
570 default:
571 {
572 // leave a breadcrumb
573 jbyte bad_value = scratch_cp->tag_at(scratch_i).value();
574 ShouldNotReachHere();
575 } break;
576 } // end switch tag value
577 } // end append_entry()
578
579
580 int VM_RedefineClasses::find_or_append_indirect_entry(const constantPoolHandle& scratch_cp,
581 int ref_i, constantPoolHandle *merge_cp_p, int *merge_cp_length_p, TRAPS) {
582
583 int new_ref_i = ref_i;
584 bool match = (ref_i < *merge_cp_length_p) &&
585 scratch_cp->compare_entry_to(ref_i, *merge_cp_p, ref_i, THREAD);
586
587 if (!match) {
588 // forward reference in *merge_cp_p or not a direct match
589 int found_i = scratch_cp->find_matching_entry(ref_i, *merge_cp_p, THREAD);
590 if (found_i != 0) {
591 guarantee(found_i != ref_i, "compare_entry_to() and find_matching_entry() do not agree");
592 // Found a matching entry somewhere else in *merge_cp_p so just need a mapping entry.
593 new_ref_i = found_i;
594 map_index(scratch_cp, ref_i, found_i);
595 } else {
596 // no match found so we have to append this entry to *merge_cp_p
597 append_entry(scratch_cp, ref_i, merge_cp_p, merge_cp_length_p, THREAD);
598 // The above call to append_entry() can only append one entry
599 // so the post call query of *merge_cp_length_p is only for
600 // the sake of consistency.
601 new_ref_i = *merge_cp_length_p - 1;
602 }
603 }
604
605 return new_ref_i;
606 } // end find_or_append_indirect_entry()
607
608
609 // Append a bootstrap specifier into the merge_cp operands that is semantically equal
610 // to the scratch_cp operands bootstrap specifier passed by the old_bs_i index.
611 // Recursively append new merge_cp entries referenced by the new bootstrap specifier.
612 void VM_RedefineClasses::append_operand(const constantPoolHandle& scratch_cp, int old_bs_i,
613 constantPoolHandle *merge_cp_p, int *merge_cp_length_p, TRAPS) {
614
615 int old_ref_i = scratch_cp->operand_bootstrap_method_ref_index_at(old_bs_i);
616 int new_ref_i = find_or_append_indirect_entry(scratch_cp, old_ref_i, merge_cp_p,
617 merge_cp_length_p, THREAD);
618 if (new_ref_i != old_ref_i) {
619 log_trace(redefine, class, constantpool)
620 ("operands entry@%d bootstrap method ref_index change: %d to %d", _operands_cur_length, old_ref_i, new_ref_i);
621 }
622
623 Array<u2>* merge_ops = (*merge_cp_p)->operands();
624 int new_bs_i = _operands_cur_length;
625 // We have _operands_cur_length == 0 when the merge_cp operands is empty yet.
626 // However, the operand_offset_at(0) was set in the extend_operands() call.
627 int new_base = (new_bs_i == 0) ? (*merge_cp_p)->operand_offset_at(0)
628 : (*merge_cp_p)->operand_next_offset_at(new_bs_i - 1);
629 int argc = scratch_cp->operand_argument_count_at(old_bs_i);
630
631 ConstantPool::operand_offset_at_put(merge_ops, _operands_cur_length, new_base);
632 merge_ops->at_put(new_base++, new_ref_i);
633 merge_ops->at_put(new_base++, argc);
634
635 for (int i = 0; i < argc; i++) {
636 int old_arg_ref_i = scratch_cp->operand_argument_index_at(old_bs_i, i);
637 int new_arg_ref_i = find_or_append_indirect_entry(scratch_cp, old_arg_ref_i, merge_cp_p,
638 merge_cp_length_p, THREAD);
639 merge_ops->at_put(new_base++, new_arg_ref_i);
640 if (new_arg_ref_i != old_arg_ref_i) {
641 log_trace(redefine, class, constantpool)
642 ("operands entry@%d bootstrap method argument ref_index change: %d to %d",
643 _operands_cur_length, old_arg_ref_i, new_arg_ref_i);
644 }
645 }
646 if (old_bs_i != _operands_cur_length) {
647 // The bootstrap specifier in *merge_cp_p is at a different index than
648 // that in scratch_cp so we need to map the index values.
649 map_operand_index(old_bs_i, new_bs_i);
650 }
651 _operands_cur_length++;
652 } // end append_operand()
653
654
655 int VM_RedefineClasses::find_or_append_operand(const constantPoolHandle& scratch_cp,
656 int old_bs_i, constantPoolHandle *merge_cp_p, int *merge_cp_length_p, TRAPS) {
657
658 int new_bs_i = old_bs_i; // bootstrap specifier index
659 bool match = (old_bs_i < _operands_cur_length) &&
660 scratch_cp->compare_operand_to(old_bs_i, *merge_cp_p, old_bs_i, THREAD);
661
662 if (!match) {
663 // forward reference in *merge_cp_p or not a direct match
664 int found_i = scratch_cp->find_matching_operand(old_bs_i, *merge_cp_p,
665 _operands_cur_length, THREAD);
666 if (found_i != -1) {
667 guarantee(found_i != old_bs_i, "compare_operand_to() and find_matching_operand() disagree");
668 // found a matching operand somewhere else in *merge_cp_p so just need a mapping
669 new_bs_i = found_i;
670 map_operand_index(old_bs_i, found_i);
671 } else {
672 // no match found so we have to append this bootstrap specifier to *merge_cp_p
673 append_operand(scratch_cp, old_bs_i, merge_cp_p, merge_cp_length_p, THREAD);
674 new_bs_i = _operands_cur_length - 1;
675 }
676 }
677 return new_bs_i;
678 } // end find_or_append_operand()
679
680
681 void VM_RedefineClasses::finalize_operands_merge(const constantPoolHandle& merge_cp, TRAPS) {
682 if (merge_cp->operands() == NULL) {
683 return;
684 }
685 // Shrink the merge_cp operands
686 merge_cp->shrink_operands(_operands_cur_length, CHECK);
687
688 if (log_is_enabled(Trace, redefine, class, constantpool)) {
689 // don't want to loop unless we are tracing
690 int count = 0;
691 for (int i = 1; i < _operands_index_map_p->length(); i++) {
692 int value = _operands_index_map_p->at(i);
693 if (value != -1) {
694 log_trace(redefine, class, constantpool)("operands_index_map[%d]: old=%d new=%d", count, i, value);
695 count++;
696 }
697 }
698 }
699 // Clean-up
700 _operands_index_map_p = NULL;
701 _operands_cur_length = 0;
702 _operands_index_map_count = 0;
703 } // end finalize_operands_merge()
704
705 // Symbol* comparator for qsort
706 // The caller must have an active ResourceMark.
707 static int symcmp(const void* a, const void* b) {
708 char* astr = (*(Symbol**)a)->as_C_string();
709 char* bstr = (*(Symbol**)b)->as_C_string();
710 return strcmp(astr, bstr);
711 }
712
713 static jvmtiError check_nest_attributes(InstanceKlass* the_class,
714 InstanceKlass* scratch_class) {
715 // Check whether the class NestHost attribute has been changed.
716 Thread* thread = Thread::current();
717 ResourceMark rm(thread);
718 u2 the_nest_host_idx = the_class->nest_host_index();
719 u2 scr_nest_host_idx = scratch_class->nest_host_index();
720
721 if (the_nest_host_idx != 0 && scr_nest_host_idx != 0) {
722 Symbol* the_sym = the_class->constants()->klass_name_at(the_nest_host_idx);
723 Symbol* scr_sym = scratch_class->constants()->klass_name_at(scr_nest_host_idx);
724 if (the_sym != scr_sym) {
725 log_trace(redefine, class, nestmates)
726 ("redefined class %s attribute change error: NestHost class: %s replaced with: %s",
727 the_class->external_name(), the_sym->as_C_string(), scr_sym->as_C_string());
728 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_CLASS_ATTRIBUTE_CHANGED;
729 }
730 } else if ((the_nest_host_idx == 0) ^ (scr_nest_host_idx == 0)) {
731 const char* action_str = (the_nest_host_idx != 0) ? "removed" : "added";
732 log_trace(redefine, class, nestmates)
733 ("redefined class %s attribute change error: NestHost attribute %s",
734 the_class->external_name(), action_str);
735 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_CLASS_ATTRIBUTE_CHANGED;
736 }
737
738 // Check whether the class NestMembers attribute has been changed.
739 Array<u2>* the_nest_members = the_class->nest_members();
740 Array<u2>* scr_nest_members = scratch_class->nest_members();
741 bool the_members_exists = the_nest_members != Universe::the_empty_short_array();
742 bool scr_members_exists = scr_nest_members != Universe::the_empty_short_array();
743
744 int members_len = the_nest_members->length();
745 if (the_members_exists && scr_members_exists) {
746 if (members_len != scr_nest_members->length()) {
747 log_trace(redefine, class, nestmates)
748 ("redefined class %s attribute change error: NestMember len=%d changed to len=%d",
749 the_class->external_name(), members_len, scr_nest_members->length());
750 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_CLASS_ATTRIBUTE_CHANGED;
751 }
752
753 // The order of entries in the NestMembers array is not specified so we
754 // have to explicitly check for the same contents. We do this by copying
755 // the referenced symbols into their own arrays, sorting them and then
756 // comparing each element pair.
757
758 Symbol** the_syms = NEW_RESOURCE_ARRAY_RETURN_NULL(Symbol*, members_len);
759 Symbol** scr_syms = NEW_RESOURCE_ARRAY_RETURN_NULL(Symbol*, members_len);
760
761 if (the_syms == NULL || scr_syms == NULL) {
762 return JVMTI_ERROR_OUT_OF_MEMORY;
763 }
764
765 for (int i = 0; i < members_len; i++) {
766 int the_cp_index = the_nest_members->at(i);
767 int scr_cp_index = scr_nest_members->at(i);
768 the_syms[i] = the_class->constants()->klass_name_at(the_cp_index);
769 scr_syms[i] = scratch_class->constants()->klass_name_at(scr_cp_index);
770 }
771
772 qsort(the_syms, members_len, sizeof(Symbol*), symcmp);
773 qsort(scr_syms, members_len, sizeof(Symbol*), symcmp);
774
775 for (int i = 0; i < members_len; i++) {
776 if (the_syms[i] != scr_syms[i]) {
777 log_trace(redefine, class, nestmates)
778 ("redefined class %s attribute change error: NestMembers[%d]: %s changed to %s",
779 the_class->external_name(), i, the_syms[i]->as_C_string(), scr_syms[i]->as_C_string());
780 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_CLASS_ATTRIBUTE_CHANGED;
781 }
782 }
783 } else if (the_members_exists ^ scr_members_exists) {
784 const char* action_str = (the_members_exists) ? "removed" : "added";
785 log_trace(redefine, class, nestmates)
786 ("redefined class %s attribute change error: NestMembers attribute %s",
787 the_class->external_name(), action_str);
788 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_CLASS_ATTRIBUTE_CHANGED;
789 }
790
791 return JVMTI_ERROR_NONE;
792 }
793
794 // Return an error status if the class Record attribute was changed.
795 static jvmtiError check_record_attribute(InstanceKlass* the_class, InstanceKlass* scratch_class) {
796 // Get lists of record components.
797 Array<RecordComponent*>* the_record = the_class->record_components();
798 Array<RecordComponent*>* scr_record = scratch_class->record_components();
799 bool the_record_exists = the_record != NULL;
800 bool scr_record_exists = scr_record != NULL;
801
802 if (the_record_exists && scr_record_exists) {
803 int the_num_components = the_record->length();
804 int scr_num_components = scr_record->length();
805 if (the_num_components != scr_num_components) {
806 log_trace(redefine, class, record)
807 ("redefined class %s attribute change error: Record num_components=%d changed to num_components=%d",
808 the_class->external_name(), the_num_components, scr_num_components);
809 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_CLASS_ATTRIBUTE_CHANGED;
810 }
811
812 // Compare each field in each record component.
813 ConstantPool* the_cp = the_class->constants();
814 ConstantPool* scr_cp = scratch_class->constants();
815 for (int x = 0; x < the_num_components; x++) {
816 RecordComponent* the_component = the_record->at(x);
817 RecordComponent* scr_component = scr_record->at(x);
818 const Symbol* const the_name = the_cp->symbol_at(the_component->name_index());
819 const Symbol* const scr_name = scr_cp->symbol_at(scr_component->name_index());
820 const Symbol* const the_descr = the_cp->symbol_at(the_component->descriptor_index());
821 const Symbol* const scr_descr = scr_cp->symbol_at(scr_component->descriptor_index());
822 if (the_name != scr_name || the_descr != scr_descr) {
823 log_trace(redefine, class, record)
824 ("redefined class %s attribute change error: Record name_index, descriptor_index, and/or attributes_count changed",
825 the_class->external_name());
826 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_CLASS_ATTRIBUTE_CHANGED;
827 }
828
829 int the_gen_sig = the_component->generic_signature_index();
830 int scr_gen_sig = scr_component->generic_signature_index();
831 const Symbol* const the_gen_sig_sym = (the_gen_sig == 0 ? NULL :
832 the_cp->symbol_at(the_component->generic_signature_index()));
833 const Symbol* const scr_gen_sig_sym = (scr_gen_sig == 0 ? NULL :
834 scr_cp->symbol_at(scr_component->generic_signature_index()));
835 if (the_gen_sig_sym != scr_gen_sig_sym) {
836 log_trace(redefine, class, record)
837 ("redefined class %s attribute change error: Record generic_signature attribute changed",
838 the_class->external_name());
839 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_CLASS_ATTRIBUTE_CHANGED;
840 }
841
842 // It's okay if a record component's annotations were changed.
843 }
844
845 } else if (the_record_exists ^ scr_record_exists) {
846 const char* action_str = (the_record_exists) ? "removed" : "added";
847 log_trace(redefine, class, record)
848 ("redefined class %s attribute change error: Record attribute %s",
849 the_class->external_name(), action_str);
850 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_CLASS_ATTRIBUTE_CHANGED;
851 }
852
853 return JVMTI_ERROR_NONE;
854 }
855
856
857 static bool can_add_or_delete(Method* m) {
858 // Compatibility mode
859 return (AllowRedefinitionToAddDeleteMethods &&
860 (m->is_private() && (m->is_static() || m->is_final())));
861 }
862
863 jvmtiError VM_RedefineClasses::compare_and_normalize_class_versions(
864 InstanceKlass* the_class,
865 InstanceKlass* scratch_class) {
866 int i;
867
868 // Check superclasses, or rather their names, since superclasses themselves can be
869 // requested to replace.
870 // Check for NULL superclass first since this might be java.lang.Object
871 if (the_class->super() != scratch_class->super() &&
872 (the_class->super() == NULL || scratch_class->super() == NULL ||
873 the_class->super()->name() !=
874 scratch_class->super()->name())) {
875 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_HIERARCHY_CHANGED;
876 }
877
878 // Check if the number, names and order of directly implemented interfaces are the same.
879 // I think in principle we should just check if the sets of names of directly implemented
880 // interfaces are the same, i.e. the order of declaration (which, however, if changed in the
881 // .java file, also changes in .class file) should not matter. However, comparing sets is
882 // technically a bit more difficult, and, more importantly, I am not sure at present that the
883 // order of interfaces does not matter on the implementation level, i.e. that the VM does not
884 // rely on it somewhere.
885 Array<InstanceKlass*>* k_interfaces = the_class->local_interfaces();
886 Array<InstanceKlass*>* k_new_interfaces = scratch_class->local_interfaces();
887 int n_intfs = k_interfaces->length();
888 if (n_intfs != k_new_interfaces->length()) {
889 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_HIERARCHY_CHANGED;
890 }
891 for (i = 0; i < n_intfs; i++) {
892 if (k_interfaces->at(i)->name() !=
893 k_new_interfaces->at(i)->name()) {
894 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_HIERARCHY_CHANGED;
895 }
896 }
897
898 // Check whether class is in the error init state.
899 if (the_class->is_in_error_state()) {
900 // TBD #5057930: special error code is needed in 1.6
901 return JVMTI_ERROR_INVALID_CLASS;
902 }
903
904 // Check whether the nest-related attributes have been changed.
905 jvmtiError err = check_nest_attributes(the_class, scratch_class);
906 if (err != JVMTI_ERROR_NONE) {
907 return err;
908 }
909
910 // Check whether the Record attribute has been changed.
911 err = check_record_attribute(the_class, scratch_class);
912 if (err != JVMTI_ERROR_NONE) {
913 return err;
914 }
915
916 // Check whether class modifiers are the same.
917 jushort old_flags = (jushort) the_class->access_flags().get_flags();
918 jushort new_flags = (jushort) scratch_class->access_flags().get_flags();
919 if (old_flags != new_flags) {
920 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_CLASS_MODIFIERS_CHANGED;
921 }
922
923 // Check if the number, names, types and order of fields declared in these classes
924 // are the same.
925 JavaFieldStream old_fs(the_class);
926 JavaFieldStream new_fs(scratch_class);
927 for (; !old_fs.done() && !new_fs.done(); old_fs.next(), new_fs.next()) {
928 // access
929 old_flags = old_fs.access_flags().as_short();
930 new_flags = new_fs.access_flags().as_short();
931 if ((old_flags ^ new_flags) & JVM_RECOGNIZED_FIELD_MODIFIERS) {
932 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_SCHEMA_CHANGED;
933 }
934 // offset
935 if (old_fs.offset() != new_fs.offset()) {
936 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_SCHEMA_CHANGED;
937 }
938 // name and signature
939 Symbol* name_sym1 = the_class->constants()->symbol_at(old_fs.name_index());
940 Symbol* sig_sym1 = the_class->constants()->symbol_at(old_fs.signature_index());
941 Symbol* name_sym2 = scratch_class->constants()->symbol_at(new_fs.name_index());
942 Symbol* sig_sym2 = scratch_class->constants()->symbol_at(new_fs.signature_index());
943 if (name_sym1 != name_sym2 || sig_sym1 != sig_sym2) {
944 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_SCHEMA_CHANGED;
945 }
946 }
947
948 // If both streams aren't done then we have a differing number of
949 // fields.
950 if (!old_fs.done() || !new_fs.done()) {
951 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_SCHEMA_CHANGED;
952 }
953
954 // Do a parallel walk through the old and new methods. Detect
955 // cases where they match (exist in both), have been added in
956 // the new methods, or have been deleted (exist only in the
957 // old methods). The class file parser places methods in order
958 // by method name, but does not order overloaded methods by
959 // signature. In order to determine what fate befell the methods,
960 // this code places the overloaded new methods that have matching
961 // old methods in the same order as the old methods and places
962 // new overloaded methods at the end of overloaded methods of
963 // that name. The code for this order normalization is adapted
964 // from the algorithm used in InstanceKlass::find_method().
965 // Since we are swapping out of order entries as we find them,
966 // we only have to search forward through the overloaded methods.
967 // Methods which are added and have the same name as an existing
968 // method (but different signature) will be put at the end of
969 // the methods with that name, and the name mismatch code will
970 // handle them.
971 Array<Method*>* k_old_methods(the_class->methods());
972 Array<Method*>* k_new_methods(scratch_class->methods());
973 int n_old_methods = k_old_methods->length();
974 int n_new_methods = k_new_methods->length();
975 Thread* thread = Thread::current();
976
977 int ni = 0;
978 int oi = 0;
979 while (true) {
980 Method* k_old_method;
981 Method* k_new_method;
982 enum { matched, added, deleted, undetermined } method_was = undetermined;
983
984 if (oi >= n_old_methods) {
985 if (ni >= n_new_methods) {
986 break; // we've looked at everything, done
987 }
988 // New method at the end
989 k_new_method = k_new_methods->at(ni);
990 method_was = added;
991 } else if (ni >= n_new_methods) {
992 // Old method, at the end, is deleted
993 k_old_method = k_old_methods->at(oi);
994 method_was = deleted;
995 } else {
996 // There are more methods in both the old and new lists
997 k_old_method = k_old_methods->at(oi);
998 k_new_method = k_new_methods->at(ni);
999 if (k_old_method->name() != k_new_method->name()) {
1000 // Methods are sorted by method name, so a mismatch means added
1001 // or deleted
1002 if (k_old_method->name()->fast_compare(k_new_method->name()) > 0) {
1003 method_was = added;
1004 } else {
1005 method_was = deleted;
1006 }
1007 } else if (k_old_method->signature() == k_new_method->signature()) {
1008 // Both the name and signature match
1009 method_was = matched;
1010 } else {
1011 // The name matches, but the signature doesn't, which means we have to
1012 // search forward through the new overloaded methods.
1013 int nj; // outside the loop for post-loop check
1014 for (nj = ni + 1; nj < n_new_methods; nj++) {
1015 Method* m = k_new_methods->at(nj);
1016 if (k_old_method->name() != m->name()) {
1017 // reached another method name so no more overloaded methods
1018 method_was = deleted;
1019 break;
1020 }
1021 if (k_old_method->signature() == m->signature()) {
1022 // found a match so swap the methods
1023 k_new_methods->at_put(ni, m);
1024 k_new_methods->at_put(nj, k_new_method);
1025 k_new_method = m;
1026 method_was = matched;
1027 break;
1028 }
1029 }
1030
1031 if (nj >= n_new_methods) {
1032 // reached the end without a match; so method was deleted
1033 method_was = deleted;
1034 }
1035 }
1036 }
1037
1038 switch (method_was) {
1039 case matched:
1040 // methods match, be sure modifiers do too
1041 old_flags = (jushort) k_old_method->access_flags().get_flags();
1042 new_flags = (jushort) k_new_method->access_flags().get_flags();
1043 if ((old_flags ^ new_flags) & ~(JVM_ACC_NATIVE)) {
1044 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_METHOD_MODIFIERS_CHANGED;
1045 }
1046 {
1047 u2 new_num = k_new_method->method_idnum();
1048 u2 old_num = k_old_method->method_idnum();
1049 if (new_num != old_num) {
1050 Method* idnum_owner = scratch_class->method_with_idnum(old_num);
1051 if (idnum_owner != NULL) {
1052 // There is already a method assigned this idnum -- switch them
1053 // Take current and original idnum from the new_method
1054 idnum_owner->set_method_idnum(new_num);
1055 idnum_owner->set_orig_method_idnum(k_new_method->orig_method_idnum());
1056 }
1057 // Take current and original idnum from the old_method
1058 k_new_method->set_method_idnum(old_num);
1059 k_new_method->set_orig_method_idnum(k_old_method->orig_method_idnum());
1060 if (thread->has_pending_exception()) {
1061 return JVMTI_ERROR_OUT_OF_MEMORY;
1062 }
1063 }
1064 }
1065 log_trace(redefine, class, normalize)
1066 ("Method matched: new: %s [%d] == old: %s [%d]",
1067 k_new_method->name_and_sig_as_C_string(), ni, k_old_method->name_and_sig_as_C_string(), oi);
1068 // advance to next pair of methods
1069 ++oi;
1070 ++ni;
1071 break;
1072 case added:
1073 // method added, see if it is OK
1074 if (!can_add_or_delete(k_new_method)) {
1075 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_METHOD_ADDED;
1076 }
1077 {
1078 u2 num = the_class->next_method_idnum();
1079 if (num == ConstMethod::UNSET_IDNUM) {
1080 // cannot add any more methods
1081 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_METHOD_ADDED;
1082 }
1083 u2 new_num = k_new_method->method_idnum();
1084 Method* idnum_owner = scratch_class->method_with_idnum(num);
1085 if (idnum_owner != NULL) {
1086 // There is already a method assigned this idnum -- switch them
1087 // Take current and original idnum from the new_method
1088 idnum_owner->set_method_idnum(new_num);
1089 idnum_owner->set_orig_method_idnum(k_new_method->orig_method_idnum());
1090 }
1091 k_new_method->set_method_idnum(num);
1092 k_new_method->set_orig_method_idnum(num);
1093 if (thread->has_pending_exception()) {
1094 return JVMTI_ERROR_OUT_OF_MEMORY;
1095 }
1096 }
1097 log_trace(redefine, class, normalize)
1098 ("Method added: new: %s [%d]", k_new_method->name_and_sig_as_C_string(), ni);
1099 ++ni; // advance to next new method
1100 break;
1101 case deleted:
1102 // method deleted, see if it is OK
1103 if (!can_add_or_delete(k_old_method)) {
1104 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_METHOD_DELETED;
1105 }
1106 log_trace(redefine, class, normalize)
1107 ("Method deleted: old: %s [%d]", k_old_method->name_and_sig_as_C_string(), oi);
1108 ++oi; // advance to next old method
1109 break;
1110 default:
1111 ShouldNotReachHere();
1112 }
1113 }
1114
1115 return JVMTI_ERROR_NONE;
1116 }
1117
1118
1119 // Find new constant pool index value for old constant pool index value
1120 // by seaching the index map. Returns zero (0) if there is no mapped
1121 // value for the old constant pool index.
1122 int VM_RedefineClasses::find_new_index(int old_index) {
1123 if (_index_map_count == 0) {
1124 // map is empty so nothing can be found
1125 return 0;
1126 }
1127
1128 if (old_index < 1 || old_index >= _index_map_p->length()) {
1129 // The old_index is out of range so it is not mapped. This should
1130 // not happen in regular constant pool merging use, but it can
1131 // happen if a corrupt annotation is processed.
1132 return 0;
1133 }
1134
1135 int value = _index_map_p->at(old_index);
1136 if (value == -1) {
1137 // the old_index is not mapped
1138 return 0;
1139 }
1140
1141 return value;
1142 } // end find_new_index()
1143
1144
1145 // Find new bootstrap specifier index value for old bootstrap specifier index
1146 // value by seaching the index map. Returns unused index (-1) if there is
1147 // no mapped value for the old bootstrap specifier index.
1148 int VM_RedefineClasses::find_new_operand_index(int old_index) {
1149 if (_operands_index_map_count == 0) {
1150 // map is empty so nothing can be found
1151 return -1;
1152 }
1153
1154 if (old_index == -1 || old_index >= _operands_index_map_p->length()) {
1155 // The old_index is out of range so it is not mapped.
1156 // This should not happen in regular constant pool merging use.
1157 return -1;
1158 }
1159
1160 int value = _operands_index_map_p->at(old_index);
1161 if (value == -1) {
1162 // the old_index is not mapped
1163 return -1;
1164 }
1165
1166 return value;
1167 } // end find_new_operand_index()
1168
1169
1170 // Returns true if the current mismatch is due to a resolved/unresolved
1171 // class pair. Otherwise, returns false.
1172 bool VM_RedefineClasses::is_unresolved_class_mismatch(const constantPoolHandle& cp1,
1173 int index1, const constantPoolHandle& cp2, int index2) {
1174
1175 jbyte t1 = cp1->tag_at(index1).value();
1176 if (t1 != JVM_CONSTANT_Class && t1 != JVM_CONSTANT_UnresolvedClass) {
1177 return false; // wrong entry type; not our special case
1178 }
1179
1180 jbyte t2 = cp2->tag_at(index2).value();
1181 if (t2 != JVM_CONSTANT_Class && t2 != JVM_CONSTANT_UnresolvedClass) {
1182 return false; // wrong entry type; not our special case
1183 }
1184
1185 if (t1 == t2) {
1186 return false; // not a mismatch; not our special case
1187 }
1188
1189 char *s1 = cp1->klass_name_at(index1)->as_C_string();
1190 char *s2 = cp2->klass_name_at(index2)->as_C_string();
1191 if (strcmp(s1, s2) != 0) {
1192 return false; // strings don't match; not our special case
1193 }
1194
1195 return true; // made it through the gauntlet; this is our special case
1196 } // end is_unresolved_class_mismatch()
1197
1198
1199 jvmtiError VM_RedefineClasses::load_new_class_versions(TRAPS) {
1200
1201 // For consistency allocate memory using os::malloc wrapper.
1202 _scratch_classes = (InstanceKlass**)
1203 os::malloc(sizeof(InstanceKlass*) * _class_count, mtClass);
1204 if (_scratch_classes == NULL) {
1205 return JVMTI_ERROR_OUT_OF_MEMORY;
1206 }
1207 // Zero initialize the _scratch_classes array.
1208 for (int i = 0; i < _class_count; i++) {
1209 _scratch_classes[i] = NULL;
1210 }
1211
1212 ResourceMark rm(THREAD);
1213
1214 JvmtiThreadState *state = JvmtiThreadState::state_for(JavaThread::current());
1215 // state can only be NULL if the current thread is exiting which
1216 // should not happen since we're trying to do a RedefineClasses
1217 guarantee(state != NULL, "exiting thread calling load_new_class_versions");
1218 for (int i = 0; i < _class_count; i++) {
1219 // Create HandleMark so that any handles created while loading new class
1220 // versions are deleted. Constant pools are deallocated while merging
1221 // constant pools
1222 HandleMark hm(THREAD);
1223 InstanceKlass* the_class = get_ik(_class_defs[i].klass);
1224 Symbol* the_class_sym = the_class->name();
1225
1226 log_debug(redefine, class, load)
1227 ("loading name=%s kind=%d (avail_mem=" UINT64_FORMAT "K)",
1228 the_class->external_name(), _class_load_kind, os::available_memory() >> 10);
1229
1230 ClassFileStream st((u1*)_class_defs[i].class_bytes,
1231 _class_defs[i].class_byte_count,
1232 "__VM_RedefineClasses__",
1233 ClassFileStream::verify);
1234
1235 // Parse the stream.
1236 Handle the_class_loader(THREAD, the_class->class_loader());
1237 Handle protection_domain(THREAD, the_class->protection_domain());
1238 // Set redefined class handle in JvmtiThreadState class.
1239 // This redefined class is sent to agent event handler for class file
1240 // load hook event.
1241 state->set_class_being_redefined(the_class, _class_load_kind);
1242
1243 ClassLoadInfo cl_info(protection_domain);
1244 InstanceKlass* scratch_class = SystemDictionary::parse_stream(
1245 the_class_sym,
1246 the_class_loader,
1247 &st,
1248 cl_info,
1249 THREAD);
1250 // Clear class_being_redefined just to be sure.
1251 state->clear_class_being_redefined();
1252
1253 // TODO: if this is retransform, and nothing changed we can skip it
1254
1255 // Need to clean up allocated InstanceKlass if there's an error so assign
1256 // the result here. Caller deallocates all the scratch classes in case of
1257 // an error.
1258 _scratch_classes[i] = scratch_class;
1259
1260 if (HAS_PENDING_EXCEPTION) {
1261 Symbol* ex_name = PENDING_EXCEPTION->klass()->name();
1262 log_info(redefine, class, load, exceptions)("parse_stream exception: '%s'", ex_name->as_C_string());
1263 CLEAR_PENDING_EXCEPTION;
1264
1265 if (ex_name == vmSymbols::java_lang_UnsupportedClassVersionError()) {
1266 return JVMTI_ERROR_UNSUPPORTED_VERSION;
1267 } else if (ex_name == vmSymbols::java_lang_ClassFormatError()) {
1268 return JVMTI_ERROR_INVALID_CLASS_FORMAT;
1269 } else if (ex_name == vmSymbols::java_lang_ClassCircularityError()) {
1270 return JVMTI_ERROR_CIRCULAR_CLASS_DEFINITION;
1271 } else if (ex_name == vmSymbols::java_lang_NoClassDefFoundError()) {
1272 // The message will be "XXX (wrong name: YYY)"
1273 return JVMTI_ERROR_NAMES_DONT_MATCH;
1274 } else if (ex_name == vmSymbols::java_lang_OutOfMemoryError()) {
1275 return JVMTI_ERROR_OUT_OF_MEMORY;
1276 } else { // Just in case more exceptions can be thrown..
1277 return JVMTI_ERROR_FAILS_VERIFICATION;
1278 }
1279 }
1280
1281 // Ensure class is linked before redefine
1282 if (!the_class->is_linked()) {
1283 the_class->link_class(THREAD);
1284 if (HAS_PENDING_EXCEPTION) {
1285 Symbol* ex_name = PENDING_EXCEPTION->klass()->name();
1286 log_info(redefine, class, load, exceptions)("link_class exception: '%s'", ex_name->as_C_string());
1287 CLEAR_PENDING_EXCEPTION;
1288 if (ex_name == vmSymbols::java_lang_OutOfMemoryError()) {
1289 return JVMTI_ERROR_OUT_OF_MEMORY;
1290 } else {
1291 return JVMTI_ERROR_INTERNAL;
1292 }
1293 }
1294 }
1295
1296 // Do the validity checks in compare_and_normalize_class_versions()
1297 // before verifying the byte codes. By doing these checks first, we
1298 // limit the number of functions that require redirection from
1299 // the_class to scratch_class. In particular, we don't have to
1300 // modify JNI GetSuperclass() and thus won't change its performance.
1301 jvmtiError res = compare_and_normalize_class_versions(the_class,
1302 scratch_class);
1303 if (res != JVMTI_ERROR_NONE) {
1304 return res;
1305 }
1306
1307 // verify what the caller passed us
1308 {
1309 // The bug 6214132 caused the verification to fail.
1310 // Information about the_class and scratch_class is temporarily
1311 // recorded into jvmtiThreadState. This data is used to redirect
1312 // the_class to scratch_class in the JVM_* functions called by the
1313 // verifier. Please, refer to jvmtiThreadState.hpp for the detailed
1314 // description.
1315 RedefineVerifyMark rvm(the_class, scratch_class, state);
1316 Verifier::verify(scratch_class, true, THREAD);
1317 }
1318
1319 if (HAS_PENDING_EXCEPTION) {
1320 Symbol* ex_name = PENDING_EXCEPTION->klass()->name();
1321 log_info(redefine, class, load, exceptions)("verify_byte_codes exception: '%s'", ex_name->as_C_string());
1322 CLEAR_PENDING_EXCEPTION;
1323 if (ex_name == vmSymbols::java_lang_OutOfMemoryError()) {
1324 return JVMTI_ERROR_OUT_OF_MEMORY;
1325 } else {
1326 // tell the caller the bytecodes are bad
1327 return JVMTI_ERROR_FAILS_VERIFICATION;
1328 }
1329 }
1330
1331 res = merge_cp_and_rewrite(the_class, scratch_class, THREAD);
1332 if (HAS_PENDING_EXCEPTION) {
1333 Symbol* ex_name = PENDING_EXCEPTION->klass()->name();
1334 log_info(redefine, class, load, exceptions)("merge_cp_and_rewrite exception: '%s'", ex_name->as_C_string());
1335 CLEAR_PENDING_EXCEPTION;
1336 if (ex_name == vmSymbols::java_lang_OutOfMemoryError()) {
1337 return JVMTI_ERROR_OUT_OF_MEMORY;
1338 } else {
1339 return JVMTI_ERROR_INTERNAL;
1340 }
1341 }
1342
1343 if (VerifyMergedCPBytecodes) {
1344 // verify what we have done during constant pool merging
1345 {
1346 RedefineVerifyMark rvm(the_class, scratch_class, state);
1347 Verifier::verify(scratch_class, true, THREAD);
1348 }
1349
1350 if (HAS_PENDING_EXCEPTION) {
1351 Symbol* ex_name = PENDING_EXCEPTION->klass()->name();
1352 log_info(redefine, class, load, exceptions)
1353 ("verify_byte_codes post merge-CP exception: '%s'", ex_name->as_C_string());
1354 CLEAR_PENDING_EXCEPTION;
1355 if (ex_name == vmSymbols::java_lang_OutOfMemoryError()) {
1356 return JVMTI_ERROR_OUT_OF_MEMORY;
1357 } else {
1358 // tell the caller that constant pool merging screwed up
1359 return JVMTI_ERROR_INTERNAL;
1360 }
1361 }
1362 }
1363
1364 Rewriter::rewrite(scratch_class, THREAD);
1365 if (!HAS_PENDING_EXCEPTION) {
1366 scratch_class->link_methods(THREAD);
1367 }
1368 if (HAS_PENDING_EXCEPTION) {
1369 Symbol* ex_name = PENDING_EXCEPTION->klass()->name();
1370 log_info(redefine, class, load, exceptions)
1371 ("Rewriter::rewrite or link_methods exception: '%s'", ex_name->as_C_string());
1372 CLEAR_PENDING_EXCEPTION;
1373 if (ex_name == vmSymbols::java_lang_OutOfMemoryError()) {
1374 return JVMTI_ERROR_OUT_OF_MEMORY;
1375 } else {
1376 return JVMTI_ERROR_INTERNAL;
1377 }
1378 }
1379
1380 log_debug(redefine, class, load)
1381 ("loaded name=%s (avail_mem=" UINT64_FORMAT "K)", the_class->external_name(), os::available_memory() >> 10);
1382 }
1383
1384 return JVMTI_ERROR_NONE;
1385 }
1386
1387
1388 // Map old_index to new_index as needed. scratch_cp is only needed
1389 // for log calls.
1390 void VM_RedefineClasses::map_index(const constantPoolHandle& scratch_cp,
1391 int old_index, int new_index) {
1392 if (find_new_index(old_index) != 0) {
1393 // old_index is already mapped
1394 return;
1395 }
1396
1397 if (old_index == new_index) {
1398 // no mapping is needed
1399 return;
1400 }
1401
1402 _index_map_p->at_put(old_index, new_index);
1403 _index_map_count++;
1404
1405 log_trace(redefine, class, constantpool)
1406 ("mapped tag %d at index %d to %d", scratch_cp->tag_at(old_index).value(), old_index, new_index);
1407 } // end map_index()
1408
1409
1410 // Map old_index to new_index as needed.
1411 void VM_RedefineClasses::map_operand_index(int old_index, int new_index) {
1412 if (find_new_operand_index(old_index) != -1) {
1413 // old_index is already mapped
1414 return;
1415 }
1416
1417 if (old_index == new_index) {
1418 // no mapping is needed
1419 return;
1420 }
1421
1422 _operands_index_map_p->at_put(old_index, new_index);
1423 _operands_index_map_count++;
1424
1425 log_trace(redefine, class, constantpool)("mapped bootstrap specifier at index %d to %d", old_index, new_index);
1426 } // end map_index()
1427
1428
1429 // Merge old_cp and scratch_cp and return the results of the merge via
1430 // merge_cp_p. The number of entries in *merge_cp_p is returned via
1431 // merge_cp_length_p. The entries in old_cp occupy the same locations
1432 // in *merge_cp_p. Also creates a map of indices from entries in
1433 // scratch_cp to the corresponding entry in *merge_cp_p. Index map
1434 // entries are only created for entries in scratch_cp that occupy a
1435 // different location in *merged_cp_p.
1436 bool VM_RedefineClasses::merge_constant_pools(const constantPoolHandle& old_cp,
1437 const constantPoolHandle& scratch_cp, constantPoolHandle *merge_cp_p,
1438 int *merge_cp_length_p, TRAPS) {
1439
1440 if (merge_cp_p == NULL) {
1441 assert(false, "caller must provide scratch constantPool");
1442 return false; // robustness
1443 }
1444 if (merge_cp_length_p == NULL) {
1445 assert(false, "caller must provide scratch CP length");
1446 return false; // robustness
1447 }
1448 // Worst case we need old_cp->length() + scratch_cp()->length(),
1449 // but the caller might be smart so make sure we have at least
1450 // the minimum.
1451 if ((*merge_cp_p)->length() < old_cp->length()) {
1452 assert(false, "merge area too small");
1453 return false; // robustness
1454 }
1455
1456 log_info(redefine, class, constantpool)("old_cp_len=%d, scratch_cp_len=%d", old_cp->length(), scratch_cp->length());
1457
1458 {
1459 // Pass 0:
1460 // The old_cp is copied to *merge_cp_p; this means that any code
1461 // using old_cp does not have to change. This work looks like a
1462 // perfect fit for ConstantPool*::copy_cp_to(), but we need to
1463 // handle one special case:
1464 // - revert JVM_CONSTANT_Class to JVM_CONSTANT_UnresolvedClass
1465 // This will make verification happy.
1466
1467 int old_i; // index into old_cp
1468
1469 // index zero (0) is not used in constantPools
1470 for (old_i = 1; old_i < old_cp->length(); old_i++) {
1471 // leave debugging crumb
1472 jbyte old_tag = old_cp->tag_at(old_i).value();
1473 switch (old_tag) {
1474 case JVM_CONSTANT_Class:
1475 case JVM_CONSTANT_UnresolvedClass:
1476 // revert the copy to JVM_CONSTANT_UnresolvedClass
1477 // May be resolving while calling this so do the same for
1478 // JVM_CONSTANT_UnresolvedClass (klass_name_at() deals with transition)
1479 (*merge_cp_p)->temp_unresolved_klass_at_put(old_i,
1480 old_cp->klass_name_index_at(old_i));
1481 break;
1482
1483 case JVM_CONSTANT_Double:
1484 case JVM_CONSTANT_Long:
1485 // just copy the entry to *merge_cp_p, but double and long take
1486 // two constant pool entries
1487 ConstantPool::copy_entry_to(old_cp, old_i, *merge_cp_p, old_i, CHECK_false);
1488 old_i++;
1489 break;
1490
1491 default:
1492 // just copy the entry to *merge_cp_p
1493 ConstantPool::copy_entry_to(old_cp, old_i, *merge_cp_p, old_i, CHECK_false);
1494 break;
1495 }
1496 } // end for each old_cp entry
1497
1498 ConstantPool::copy_operands(old_cp, *merge_cp_p, CHECK_false);
1499 (*merge_cp_p)->extend_operands(scratch_cp, CHECK_false);
1500
1501 // We don't need to sanity check that *merge_cp_length_p is within
1502 // *merge_cp_p bounds since we have the minimum on-entry check above.
1503 (*merge_cp_length_p) = old_i;
1504 }
1505
1506 // merge_cp_len should be the same as old_cp->length() at this point
1507 // so this trace message is really a "warm-and-breathing" message.
1508 log_debug(redefine, class, constantpool)("after pass 0: merge_cp_len=%d", *merge_cp_length_p);
1509
1510 int scratch_i; // index into scratch_cp
1511 {
1512 // Pass 1a:
1513 // Compare scratch_cp entries to the old_cp entries that we have
1514 // already copied to *merge_cp_p. In this pass, we are eliminating
1515 // exact duplicates (matching entry at same index) so we only
1516 // compare entries in the common indice range.
1517 int increment = 1;
1518 int pass1a_length = MIN2(old_cp->length(), scratch_cp->length());
1519 for (scratch_i = 1; scratch_i < pass1a_length; scratch_i += increment) {
1520 switch (scratch_cp->tag_at(scratch_i).value()) {
1521 case JVM_CONSTANT_Double:
1522 case JVM_CONSTANT_Long:
1523 // double and long take two constant pool entries
1524 increment = 2;
1525 break;
1526
1527 default:
1528 increment = 1;
1529 break;
1530 }
1531
1532 bool match = scratch_cp->compare_entry_to(scratch_i, *merge_cp_p,
1533 scratch_i, CHECK_false);
1534 if (match) {
1535 // found a match at the same index so nothing more to do
1536 continue;
1537 } else if (is_unresolved_class_mismatch(scratch_cp, scratch_i,
1538 *merge_cp_p, scratch_i)) {
1539 // The mismatch in compare_entry_to() above is because of a
1540 // resolved versus unresolved class entry at the same index
1541 // with the same string value. Since Pass 0 reverted any
1542 // class entries to unresolved class entries in *merge_cp_p,
1543 // we go with the unresolved class entry.
1544 continue;
1545 }
1546
1547 int found_i = scratch_cp->find_matching_entry(scratch_i, *merge_cp_p,
1548 CHECK_false);
1549 if (found_i != 0) {
1550 guarantee(found_i != scratch_i,
1551 "compare_entry_to() and find_matching_entry() do not agree");
1552
1553 // Found a matching entry somewhere else in *merge_cp_p so
1554 // just need a mapping entry.
1555 map_index(scratch_cp, scratch_i, found_i);
1556 continue;
1557 }
1558
1559 // The find_matching_entry() call above could fail to find a match
1560 // due to a resolved versus unresolved class or string entry situation
1561 // like we solved above with the is_unresolved_*_mismatch() calls.
1562 // However, we would have to call is_unresolved_*_mismatch() over
1563 // all of *merge_cp_p (potentially) and that doesn't seem to be
1564 // worth the time.
1565
1566 // No match found so we have to append this entry and any unique
1567 // referenced entries to *merge_cp_p.
1568 append_entry(scratch_cp, scratch_i, merge_cp_p, merge_cp_length_p,
1569 CHECK_false);
1570 }
1571 }
1572
1573 log_debug(redefine, class, constantpool)
1574 ("after pass 1a: merge_cp_len=%d, scratch_i=%d, index_map_len=%d",
1575 *merge_cp_length_p, scratch_i, _index_map_count);
1576
1577 if (scratch_i < scratch_cp->length()) {
1578 // Pass 1b:
1579 // old_cp is smaller than scratch_cp so there are entries in
1580 // scratch_cp that we have not yet processed. We take care of
1581 // those now.
1582 int increment = 1;
1583 for (; scratch_i < scratch_cp->length(); scratch_i += increment) {
1584 switch (scratch_cp->tag_at(scratch_i).value()) {
1585 case JVM_CONSTANT_Double:
1586 case JVM_CONSTANT_Long:
1587 // double and long take two constant pool entries
1588 increment = 2;
1589 break;
1590
1591 default:
1592 increment = 1;
1593 break;
1594 }
1595
1596 int found_i =
1597 scratch_cp->find_matching_entry(scratch_i, *merge_cp_p, CHECK_false);
1598 if (found_i != 0) {
1599 // Found a matching entry somewhere else in *merge_cp_p so
1600 // just need a mapping entry.
1601 map_index(scratch_cp, scratch_i, found_i);
1602 continue;
1603 }
1604
1605 // No match found so we have to append this entry and any unique
1606 // referenced entries to *merge_cp_p.
1607 append_entry(scratch_cp, scratch_i, merge_cp_p, merge_cp_length_p,
1608 CHECK_false);
1609 }
1610
1611 log_debug(redefine, class, constantpool)
1612 ("after pass 1b: merge_cp_len=%d, scratch_i=%d, index_map_len=%d",
1613 *merge_cp_length_p, scratch_i, _index_map_count);
1614 }
1615 finalize_operands_merge(*merge_cp_p, THREAD);
1616
1617 return true;
1618 } // end merge_constant_pools()
1619
1620
1621 // Scoped object to clean up the constant pool(s) created for merging
1622 class MergeCPCleaner {
1623 ClassLoaderData* _loader_data;
1624 ConstantPool* _cp;
1625 ConstantPool* _scratch_cp;
1626 public:
1627 MergeCPCleaner(ClassLoaderData* loader_data, ConstantPool* merge_cp) :
1628 _loader_data(loader_data), _cp(merge_cp), _scratch_cp(NULL) {}
1629 ~MergeCPCleaner() {
1630 _loader_data->add_to_deallocate_list(_cp);
1631 if (_scratch_cp != NULL) {
1632 _loader_data->add_to_deallocate_list(_scratch_cp);
1633 }
1634 }
1635 void add_scratch_cp(ConstantPool* scratch_cp) { _scratch_cp = scratch_cp; }
1636 };
1637
1638 // Merge constant pools between the_class and scratch_class and
1639 // potentially rewrite bytecodes in scratch_class to use the merged
1640 // constant pool.
1641 jvmtiError VM_RedefineClasses::merge_cp_and_rewrite(
1642 InstanceKlass* the_class, InstanceKlass* scratch_class,
1643 TRAPS) {
1644 // worst case merged constant pool length is old and new combined
1645 int merge_cp_length = the_class->constants()->length()
1646 + scratch_class->constants()->length();
1647
1648 // Constant pools are not easily reused so we allocate a new one
1649 // each time.
1650 // merge_cp is created unsafe for concurrent GC processing. It
1651 // should be marked safe before discarding it. Even though
1652 // garbage, if it crosses a card boundary, it may be scanned
1653 // in order to find the start of the first complete object on the card.
1654 ClassLoaderData* loader_data = the_class->class_loader_data();
1655 ConstantPool* merge_cp_oop =
1656 ConstantPool::allocate(loader_data,
1657 merge_cp_length,
1658 CHECK_(JVMTI_ERROR_OUT_OF_MEMORY));
1659 MergeCPCleaner cp_cleaner(loader_data, merge_cp_oop);
1660
1661 HandleMark hm(THREAD); // make sure handles are cleared before
1662 // MergeCPCleaner clears out merge_cp_oop
1663 constantPoolHandle merge_cp(THREAD, merge_cp_oop);
1664
1665 // Get constants() from the old class because it could have been rewritten
1666 // while we were at a safepoint allocating a new constant pool.
1667 constantPoolHandle old_cp(THREAD, the_class->constants());
1668 constantPoolHandle scratch_cp(THREAD, scratch_class->constants());
1669
1670 // If the length changed, the class was redefined out from under us. Return
1671 // an error.
1672 if (merge_cp_length != the_class->constants()->length()
1673 + scratch_class->constants()->length()) {
1674 return JVMTI_ERROR_INTERNAL;
1675 }
1676
1677 // Update the version number of the constant pools (may keep scratch_cp)
1678 merge_cp->increment_and_save_version(old_cp->version());
1679 scratch_cp->increment_and_save_version(old_cp->version());
1680
1681 ResourceMark rm(THREAD);
1682 _index_map_count = 0;
1683 _index_map_p = new intArray(scratch_cp->length(), scratch_cp->length(), -1);
1684
1685 _operands_cur_length = ConstantPool::operand_array_length(old_cp->operands());
1686 _operands_index_map_count = 0;
1687 int operands_index_map_len = ConstantPool::operand_array_length(scratch_cp->operands());
1688 _operands_index_map_p = new intArray(operands_index_map_len, operands_index_map_len, -1);
1689
1690 // reference to the cp holder is needed for copy_operands()
1691 merge_cp->set_pool_holder(scratch_class);
1692 bool result = merge_constant_pools(old_cp, scratch_cp, &merge_cp,
1693 &merge_cp_length, THREAD);
1694 merge_cp->set_pool_holder(NULL);
1695
1696 if (!result) {
1697 // The merge can fail due to memory allocation failure or due
1698 // to robustness checks.
1699 return JVMTI_ERROR_INTERNAL;
1700 }
1701
1702 if (old_cp->has_dynamic_constant()) {
1703 merge_cp->set_has_dynamic_constant();
1704 scratch_cp->set_has_dynamic_constant();
1705 }
1706
1707 log_info(redefine, class, constantpool)("merge_cp_len=%d, index_map_len=%d", merge_cp_length, _index_map_count);
1708
1709 if (_index_map_count == 0) {
1710 // there is nothing to map between the new and merged constant pools
1711
1712 if (old_cp->length() == scratch_cp->length()) {
1713 // The old and new constant pools are the same length and the
1714 // index map is empty. This means that the three constant pools
1715 // are equivalent (but not the same). Unfortunately, the new
1716 // constant pool has not gone through link resolution nor have
1717 // the new class bytecodes gone through constant pool cache
1718 // rewriting so we can't use the old constant pool with the new
1719 // class.
1720
1721 // toss the merged constant pool at return
1722 } else if (old_cp->length() < scratch_cp->length()) {
1723 // The old constant pool has fewer entries than the new constant
1724 // pool and the index map is empty. This means the new constant
1725 // pool is a superset of the old constant pool. However, the old
1726 // class bytecodes have already gone through constant pool cache
1727 // rewriting so we can't use the new constant pool with the old
1728 // class.
1729
1730 // toss the merged constant pool at return
1731 } else {
1732 // The old constant pool has more entries than the new constant
1733 // pool and the index map is empty. This means that both the old
1734 // and merged constant pools are supersets of the new constant
1735 // pool.
1736
1737 // Replace the new constant pool with a shrunken copy of the
1738 // merged constant pool
1739 set_new_constant_pool(loader_data, scratch_class, merge_cp, merge_cp_length,
1740 CHECK_(JVMTI_ERROR_OUT_OF_MEMORY));
1741 // The new constant pool replaces scratch_cp so have cleaner clean it up.
1742 // It can't be cleaned up while there are handles to it.
1743 cp_cleaner.add_scratch_cp(scratch_cp());
1744 }
1745 } else {
1746 if (log_is_enabled(Trace, redefine, class, constantpool)) {
1747 // don't want to loop unless we are tracing
1748 int count = 0;
1749 for (int i = 1; i < _index_map_p->length(); i++) {
1750 int value = _index_map_p->at(i);
1751
1752 if (value != -1) {
1753 log_trace(redefine, class, constantpool)("index_map[%d]: old=%d new=%d", count, i, value);
1754 count++;
1755 }
1756 }
1757 }
1758
1759 // We have entries mapped between the new and merged constant pools
1760 // so we have to rewrite some constant pool references.
1761 if (!rewrite_cp_refs(scratch_class, THREAD)) {
1762 return JVMTI_ERROR_INTERNAL;
1763 }
1764
1765 // Replace the new constant pool with a shrunken copy of the
1766 // merged constant pool so now the rewritten bytecodes have
1767 // valid references; the previous new constant pool will get
1768 // GCed.
1769 set_new_constant_pool(loader_data, scratch_class, merge_cp, merge_cp_length,
1770 CHECK_(JVMTI_ERROR_OUT_OF_MEMORY));
1771 // The new constant pool replaces scratch_cp so have cleaner clean it up.
1772 // It can't be cleaned up while there are handles to it.
1773 cp_cleaner.add_scratch_cp(scratch_cp());
1774 }
1775
1776 return JVMTI_ERROR_NONE;
1777 } // end merge_cp_and_rewrite()
1778
1779
1780 // Rewrite constant pool references in klass scratch_class.
1781 bool VM_RedefineClasses::rewrite_cp_refs(InstanceKlass* scratch_class,
1782 TRAPS) {
1783
1784 // rewrite constant pool references in the nest attributes:
1785 if (!rewrite_cp_refs_in_nest_attributes(scratch_class)) {
1786 // propagate failure back to caller
1787 return false;
1788 }
1789
1790 // rewrite constant pool references in the Record attribute:
1791 if (!rewrite_cp_refs_in_record_attribute(scratch_class, THREAD)) {
1792 // propagate failure back to caller
1793 return false;
1794 }
1795
1796 // rewrite constant pool references in the methods:
1797 if (!rewrite_cp_refs_in_methods(scratch_class, THREAD)) {
1798 // propagate failure back to caller
1799 return false;
1800 }
1801
1802 // rewrite constant pool references in the class_annotations:
1803 if (!rewrite_cp_refs_in_class_annotations(scratch_class, THREAD)) {
1804 // propagate failure back to caller
1805 return false;
1806 }
1807
1808 // rewrite constant pool references in the fields_annotations:
1809 if (!rewrite_cp_refs_in_fields_annotations(scratch_class, THREAD)) {
1810 // propagate failure back to caller
1811 return false;
1812 }
1813
1814 // rewrite constant pool references in the methods_annotations:
1815 if (!rewrite_cp_refs_in_methods_annotations(scratch_class, THREAD)) {
1816 // propagate failure back to caller
1817 return false;
1818 }
1819
1820 // rewrite constant pool references in the methods_parameter_annotations:
1821 if (!rewrite_cp_refs_in_methods_parameter_annotations(scratch_class,
1822 THREAD)) {
1823 // propagate failure back to caller
1824 return false;
1825 }
1826
1827 // rewrite constant pool references in the methods_default_annotations:
1828 if (!rewrite_cp_refs_in_methods_default_annotations(scratch_class,
1829 THREAD)) {
1830 // propagate failure back to caller
1831 return false;
1832 }
1833
1834 // rewrite constant pool references in the class_type_annotations:
1835 if (!rewrite_cp_refs_in_class_type_annotations(scratch_class, THREAD)) {
1836 // propagate failure back to caller
1837 return false;
1838 }
1839
1840 // rewrite constant pool references in the fields_type_annotations:
1841 if (!rewrite_cp_refs_in_fields_type_annotations(scratch_class, THREAD)) {
1842 // propagate failure back to caller
1843 return false;
1844 }
1845
1846 // rewrite constant pool references in the methods_type_annotations:
1847 if (!rewrite_cp_refs_in_methods_type_annotations(scratch_class, THREAD)) {
1848 // propagate failure back to caller
1849 return false;
1850 }
1851
1852 // There can be type annotations in the Code part of a method_info attribute.
1853 // These annotations are not accessible, even by reflection.
1854 // Currently they are not even parsed by the ClassFileParser.
1855 // If runtime access is added they will also need to be rewritten.
1856
1857 // rewrite source file name index:
1858 u2 source_file_name_idx = scratch_class->source_file_name_index();
1859 if (source_file_name_idx != 0) {
1860 u2 new_source_file_name_idx = find_new_index(source_file_name_idx);
1861 if (new_source_file_name_idx != 0) {
1862 scratch_class->set_source_file_name_index(new_source_file_name_idx);
1863 }
1864 }
1865
1866 // rewrite class generic signature index:
1867 u2 generic_signature_index = scratch_class->generic_signature_index();
1868 if (generic_signature_index != 0) {
1869 u2 new_generic_signature_index = find_new_index(generic_signature_index);
1870 if (new_generic_signature_index != 0) {
1871 scratch_class->set_generic_signature_index(new_generic_signature_index);
1872 }
1873 }
1874
1875 return true;
1876 } // end rewrite_cp_refs()
1877
1878 // Rewrite constant pool references in the NestHost and NestMembers attributes.
1879 bool VM_RedefineClasses::rewrite_cp_refs_in_nest_attributes(
1880 InstanceKlass* scratch_class) {
1881
1882 u2 cp_index = scratch_class->nest_host_index();
1883 if (cp_index != 0) {
1884 scratch_class->set_nest_host_index(find_new_index(cp_index));
1885 }
1886 Array<u2>* nest_members = scratch_class->nest_members();
1887 for (int i = 0; i < nest_members->length(); i++) {
1888 u2 cp_index = nest_members->at(i);
1889 nest_members->at_put(i, find_new_index(cp_index));
1890 }
1891 return true;
1892 }
1893
1894 // Rewrite constant pool references in the Record attribute.
1895 bool VM_RedefineClasses::rewrite_cp_refs_in_record_attribute(
1896 InstanceKlass* scratch_class, TRAPS) {
1897 Array<RecordComponent*>* components = scratch_class->record_components();
1898 if (components != NULL) {
1899 for (int i = 0; i < components->length(); i++) {
1900 RecordComponent* component = components->at(i);
1901 u2 cp_index = component->name_index();
1902 component->set_name_index(find_new_index(cp_index));
1903 cp_index = component->descriptor_index();
1904 component->set_descriptor_index(find_new_index(cp_index));
1905 cp_index = component->generic_signature_index();
1906 if (cp_index != 0) {
1907 component->set_generic_signature_index(find_new_index(cp_index));
1908 }
1909
1910 AnnotationArray* annotations = component->annotations();
1911 if (annotations != NULL && annotations->length() != 0) {
1912 int byte_i = 0; // byte index into annotations
1913 if (!rewrite_cp_refs_in_annotations_typeArray(annotations, byte_i, THREAD)) {
1914 log_debug(redefine, class, annotation)("bad record_component_annotations at %d", i);
1915 // propagate failure back to caller
1916 return false;
1917 }
1918 }
1919
1920 AnnotationArray* type_annotations = component->type_annotations();
1921 if (type_annotations != NULL && type_annotations->length() != 0) {
1922 int byte_i = 0; // byte index into annotations
1923 if (!rewrite_cp_refs_in_annotations_typeArray(type_annotations, byte_i, THREAD)) {
1924 log_debug(redefine, class, annotation)("bad record_component_type_annotations at %d", i);
1925 // propagate failure back to caller
1926 return false;
1927 }
1928 }
1929 }
1930 }
1931 return true;
1932 }
1933
1934 // Rewrite constant pool references in the methods.
1935 bool VM_RedefineClasses::rewrite_cp_refs_in_methods(
1936 InstanceKlass* scratch_class, TRAPS) {
1937
1938 Array<Method*>* methods = scratch_class->methods();
1939
1940 if (methods == NULL || methods->length() == 0) {
1941 // no methods so nothing to do
1942 return true;
1943 }
1944
1945 // rewrite constant pool references in the methods:
1946 for (int i = methods->length() - 1; i >= 0; i--) {
1947 methodHandle method(THREAD, methods->at(i));
1948 methodHandle new_method;
1949 rewrite_cp_refs_in_method(method, &new_method, THREAD);
1950 if (!new_method.is_null()) {
1951 // the method has been replaced so save the new method version
1952 // even in the case of an exception. original method is on the
1953 // deallocation list.
1954 methods->at_put(i, new_method());
1955 }
1956 if (HAS_PENDING_EXCEPTION) {
1957 Symbol* ex_name = PENDING_EXCEPTION->klass()->name();
1958 log_info(redefine, class, load, exceptions)("rewrite_cp_refs_in_method exception: '%s'", ex_name->as_C_string());
1959 // Need to clear pending exception here as the super caller sets
1960 // the JVMTI_ERROR_INTERNAL if the returned value is false.
1961 CLEAR_PENDING_EXCEPTION;
1962 return false;
1963 }
1964 }
1965
1966 return true;
1967 }
1968
1969
1970 // Rewrite constant pool references in the specific method. This code
1971 // was adapted from Rewriter::rewrite_method().
1972 void VM_RedefineClasses::rewrite_cp_refs_in_method(methodHandle method,
1973 methodHandle *new_method_p, TRAPS) {
1974
1975 *new_method_p = methodHandle(); // default is no new method
1976
1977 // We cache a pointer to the bytecodes here in code_base. If GC
1978 // moves the Method*, then the bytecodes will also move which
1979 // will likely cause a crash. We create a NoSafepointVerifier
1980 // object to detect whether we pass a possible safepoint in this
1981 // code block.
1982 NoSafepointVerifier nsv;
1983
1984 // Bytecodes and their length
1985 address code_base = method->code_base();
1986 int code_length = method->code_size();
1987
1988 int bc_length;
1989 for (int bci = 0; bci < code_length; bci += bc_length) {
1990 address bcp = code_base + bci;
1991 Bytecodes::Code c = (Bytecodes::Code)(*bcp);
1992
1993 bc_length = Bytecodes::length_for(c);
1994 if (bc_length == 0) {
1995 // More complicated bytecodes report a length of zero so
1996 // we have to try again a slightly different way.
1997 bc_length = Bytecodes::length_at(method(), bcp);
1998 }
1999
2000 assert(bc_length != 0, "impossible bytecode length");
2001
2002 switch (c) {
2003 case Bytecodes::_ldc:
2004 {
2005 int cp_index = *(bcp + 1);
2006 int new_index = find_new_index(cp_index);
2007
2008 if (StressLdcRewrite && new_index == 0) {
2009 // If we are stressing ldc -> ldc_w rewriting, then we
2010 // always need a new_index value.
2011 new_index = cp_index;
2012 }
2013 if (new_index != 0) {
2014 // the original index is mapped so we have more work to do
2015 if (!StressLdcRewrite && new_index <= max_jubyte) {
2016 // The new value can still use ldc instead of ldc_w
2017 // unless we are trying to stress ldc -> ldc_w rewriting
2018 log_trace(redefine, class, constantpool)
2019 ("%s@" INTPTR_FORMAT " old=%d, new=%d", Bytecodes::name(c), p2i(bcp), cp_index, new_index);
2020 *(bcp + 1) = new_index;
2021 } else {
2022 log_trace(redefine, class, constantpool)
2023 ("%s->ldc_w@" INTPTR_FORMAT " old=%d, new=%d", Bytecodes::name(c), p2i(bcp), cp_index, new_index);
2024 // the new value needs ldc_w instead of ldc
2025 u_char inst_buffer[4]; // max instruction size is 4 bytes
2026 bcp = (address)inst_buffer;
2027 // construct new instruction sequence
2028 *bcp = Bytecodes::_ldc_w;
2029 bcp++;
2030 // Rewriter::rewrite_method() does not rewrite ldc -> ldc_w.
2031 // See comment below for difference between put_Java_u2()
2032 // and put_native_u2().
2033 Bytes::put_Java_u2(bcp, new_index);
2034
2035 Relocator rc(method, NULL /* no RelocatorListener needed */);
2036 methodHandle m;
2037 {
2038 PauseNoSafepointVerifier pnsv(&nsv);
2039
2040 // ldc is 2 bytes and ldc_w is 3 bytes
2041 m = rc.insert_space_at(bci, 3, inst_buffer, CHECK);
2042 }
2043
2044 // return the new method so that the caller can update
2045 // the containing class
2046 *new_method_p = method = m;
2047 // switch our bytecode processing loop from the old method
2048 // to the new method
2049 code_base = method->code_base();
2050 code_length = method->code_size();
2051 bcp = code_base + bci;
2052 c = (Bytecodes::Code)(*bcp);
2053 bc_length = Bytecodes::length_for(c);
2054 assert(bc_length != 0, "sanity check");
2055 } // end we need ldc_w instead of ldc
2056 } // end if there is a mapped index
2057 } break;
2058
2059 // these bytecodes have a two-byte constant pool index
2060 case Bytecodes::_anewarray : // fall through
2061 case Bytecodes::_checkcast : // fall through
2062 case Bytecodes::_getfield : // fall through
2063 case Bytecodes::_getstatic : // fall through
2064 case Bytecodes::_instanceof : // fall through
2065 case Bytecodes::_invokedynamic : // fall through
2066 case Bytecodes::_invokeinterface: // fall through
2067 case Bytecodes::_invokespecial : // fall through
2068 case Bytecodes::_invokestatic : // fall through
2069 case Bytecodes::_invokevirtual : // fall through
2070 case Bytecodes::_ldc_w : // fall through
2071 case Bytecodes::_ldc2_w : // fall through
2072 case Bytecodes::_multianewarray : // fall through
2073 case Bytecodes::_new : // fall through
2074 case Bytecodes::_putfield : // fall through
2075 case Bytecodes::_putstatic :
2076 {
2077 address p = bcp + 1;
2078 int cp_index = Bytes::get_Java_u2(p);
2079 int new_index = find_new_index(cp_index);
2080 if (new_index != 0) {
2081 // the original index is mapped so update w/ new value
2082 log_trace(redefine, class, constantpool)
2083 ("%s@" INTPTR_FORMAT " old=%d, new=%d", Bytecodes::name(c),p2i(bcp), cp_index, new_index);
2084 // Rewriter::rewrite_method() uses put_native_u2() in this
2085 // situation because it is reusing the constant pool index
2086 // location for a native index into the ConstantPoolCache.
2087 // Since we are updating the constant pool index prior to
2088 // verification and ConstantPoolCache initialization, we
2089 // need to keep the new index in Java byte order.
2090 Bytes::put_Java_u2(p, new_index);
2091 }
2092 } break;
2093 default:
2094 break;
2095 }
2096 } // end for each bytecode
2097
2098 // We also need to rewrite the parameter name indexes, if there is
2099 // method parameter data present
2100 if(method->has_method_parameters()) {
2101 const int len = method->method_parameters_length();
2102 MethodParametersElement* elem = method->method_parameters_start();
2103
2104 for (int i = 0; i < len; i++) {
2105 const u2 cp_index = elem[i].name_cp_index;
2106 const u2 new_cp_index = find_new_index(cp_index);
2107 if (new_cp_index != 0) {
2108 elem[i].name_cp_index = new_cp_index;
2109 }
2110 }
2111 }
2112 } // end rewrite_cp_refs_in_method()
2113
2114
2115 // Rewrite constant pool references in the class_annotations field.
2116 bool VM_RedefineClasses::rewrite_cp_refs_in_class_annotations(
2117 InstanceKlass* scratch_class, TRAPS) {
2118
2119 AnnotationArray* class_annotations = scratch_class->class_annotations();
2120 if (class_annotations == NULL || class_annotations->length() == 0) {
2121 // no class_annotations so nothing to do
2122 return true;
2123 }
2124
2125 log_debug(redefine, class, annotation)("class_annotations length=%d", class_annotations->length());
2126
2127 int byte_i = 0; // byte index into class_annotations
2128 return rewrite_cp_refs_in_annotations_typeArray(class_annotations, byte_i,
2129 THREAD);
2130 }
2131
2132
2133 // Rewrite constant pool references in an annotations typeArray. This
2134 // "structure" is adapted from the RuntimeVisibleAnnotations_attribute
2135 // that is described in section 4.8.15 of the 2nd-edition of the VM spec:
2136 //
2137 // annotations_typeArray {
2138 // u2 num_annotations;
2139 // annotation annotations[num_annotations];
2140 // }
2141 //
2142 bool VM_RedefineClasses::rewrite_cp_refs_in_annotations_typeArray(
2143 AnnotationArray* annotations_typeArray, int &byte_i_ref, TRAPS) {
2144
2145 if ((byte_i_ref + 2) > annotations_typeArray->length()) {
2146 // not enough room for num_annotations field
2147 log_debug(redefine, class, annotation)("length() is too small for num_annotations field");
2148 return false;
2149 }
2150
2151 u2 num_annotations = Bytes::get_Java_u2((address)
2152 annotations_typeArray->adr_at(byte_i_ref));
2153 byte_i_ref += 2;
2154
2155 log_debug(redefine, class, annotation)("num_annotations=%d", num_annotations);
2156
2157 int calc_num_annotations = 0;
2158 for (; calc_num_annotations < num_annotations; calc_num_annotations++) {
2159 if (!rewrite_cp_refs_in_annotation_struct(annotations_typeArray,
2160 byte_i_ref, THREAD)) {
2161 log_debug(redefine, class, annotation)("bad annotation_struct at %d", calc_num_annotations);
2162 // propagate failure back to caller
2163 return false;
2164 }
2165 }
2166 assert(num_annotations == calc_num_annotations, "sanity check");
2167
2168 return true;
2169 } // end rewrite_cp_refs_in_annotations_typeArray()
2170
2171
2172 // Rewrite constant pool references in the annotation struct portion of
2173 // an annotations_typeArray. This "structure" is from section 4.8.15 of
2174 // the 2nd-edition of the VM spec:
2175 //
2176 // struct annotation {
2177 // u2 type_index;
2178 // u2 num_element_value_pairs;
2179 // {
2180 // u2 element_name_index;
2181 // element_value value;
2182 // } element_value_pairs[num_element_value_pairs];
2183 // }
2184 //
2185 bool VM_RedefineClasses::rewrite_cp_refs_in_annotation_struct(
2186 AnnotationArray* annotations_typeArray, int &byte_i_ref, TRAPS) {
2187 if ((byte_i_ref + 2 + 2) > annotations_typeArray->length()) {
2188 // not enough room for smallest annotation_struct
2189 log_debug(redefine, class, annotation)("length() is too small for annotation_struct");
2190 return false;
2191 }
2192
2193 u2 type_index = rewrite_cp_ref_in_annotation_data(annotations_typeArray,
2194 byte_i_ref, "type_index", THREAD);
2195
2196 u2 num_element_value_pairs = Bytes::get_Java_u2((address)
2197 annotations_typeArray->adr_at(byte_i_ref));
2198 byte_i_ref += 2;
2199
2200 log_debug(redefine, class, annotation)
2201 ("type_index=%d num_element_value_pairs=%d", type_index, num_element_value_pairs);
2202
2203 int calc_num_element_value_pairs = 0;
2204 for (; calc_num_element_value_pairs < num_element_value_pairs;
2205 calc_num_element_value_pairs++) {
2206 if ((byte_i_ref + 2) > annotations_typeArray->length()) {
2207 // not enough room for another element_name_index, let alone
2208 // the rest of another component
2209 log_debug(redefine, class, annotation)("length() is too small for element_name_index");
2210 return false;
2211 }
2212
2213 u2 element_name_index = rewrite_cp_ref_in_annotation_data(
2214 annotations_typeArray, byte_i_ref,
2215 "element_name_index", THREAD);
2216
2217 log_debug(redefine, class, annotation)("element_name_index=%d", element_name_index);
2218
2219 if (!rewrite_cp_refs_in_element_value(annotations_typeArray,
2220 byte_i_ref, THREAD)) {
2221 log_debug(redefine, class, annotation)("bad element_value at %d", calc_num_element_value_pairs);
2222 // propagate failure back to caller
2223 return false;
2224 }
2225 } // end for each component
2226 assert(num_element_value_pairs == calc_num_element_value_pairs,
2227 "sanity check");
2228
2229 return true;
2230 } // end rewrite_cp_refs_in_annotation_struct()
2231
2232
2233 // Rewrite a constant pool reference at the current position in
2234 // annotations_typeArray if needed. Returns the original constant
2235 // pool reference if a rewrite was not needed or the new constant
2236 // pool reference if a rewrite was needed.
2237 u2 VM_RedefineClasses::rewrite_cp_ref_in_annotation_data(
2238 AnnotationArray* annotations_typeArray, int &byte_i_ref,
2239 const char * trace_mesg, TRAPS) {
2240
2241 address cp_index_addr = (address)
2242 annotations_typeArray->adr_at(byte_i_ref);
2243 u2 old_cp_index = Bytes::get_Java_u2(cp_index_addr);
2244 u2 new_cp_index = find_new_index(old_cp_index);
2245 if (new_cp_index != 0) {
2246 log_debug(redefine, class, annotation)("mapped old %s=%d", trace_mesg, old_cp_index);
2247 Bytes::put_Java_u2(cp_index_addr, new_cp_index);
2248 old_cp_index = new_cp_index;
2249 }
2250 byte_i_ref += 2;
2251 return old_cp_index;
2252 }
2253
2254
2255 // Rewrite constant pool references in the element_value portion of an
2256 // annotations_typeArray. This "structure" is from section 4.8.15.1 of
2257 // the 2nd-edition of the VM spec:
2258 //
2259 // struct element_value {
2260 // u1 tag;
2261 // union {
2262 // u2 const_value_index;
2263 // {
2264 // u2 type_name_index;
2265 // u2 const_name_index;
2266 // } enum_const_value;
2267 // u2 class_info_index;
2268 // annotation annotation_value;
2269 // struct {
2270 // u2 num_values;
2271 // element_value values[num_values];
2272 // } array_value;
2273 // } value;
2274 // }
2275 //
2276 bool VM_RedefineClasses::rewrite_cp_refs_in_element_value(
2277 AnnotationArray* annotations_typeArray, int &byte_i_ref, TRAPS) {
2278
2279 if ((byte_i_ref + 1) > annotations_typeArray->length()) {
2280 // not enough room for a tag let alone the rest of an element_value
2281 log_debug(redefine, class, annotation)("length() is too small for a tag");
2282 return false;
2283 }
2284
2285 u1 tag = annotations_typeArray->at(byte_i_ref);
2286 byte_i_ref++;
2287 log_debug(redefine, class, annotation)("tag='%c'", tag);
2288
2289 switch (tag) {
2290 // These BaseType tag values are from Table 4.2 in VM spec:
2291 case JVM_SIGNATURE_BYTE:
2292 case JVM_SIGNATURE_CHAR:
2293 case JVM_SIGNATURE_DOUBLE:
2294 case JVM_SIGNATURE_FLOAT:
2295 case JVM_SIGNATURE_INT:
2296 case JVM_SIGNATURE_LONG:
2297 case JVM_SIGNATURE_SHORT:
2298 case JVM_SIGNATURE_BOOLEAN:
2299
2300 // The remaining tag values are from Table 4.8 in the 2nd-edition of
2301 // the VM spec:
2302 case 's':
2303 {
2304 // For the above tag values (including the BaseType values),
2305 // value.const_value_index is right union field.
2306
2307 if ((byte_i_ref + 2) > annotations_typeArray->length()) {
2308 // not enough room for a const_value_index
2309 log_debug(redefine, class, annotation)("length() is too small for a const_value_index");
2310 return false;
2311 }
2312
2313 u2 const_value_index = rewrite_cp_ref_in_annotation_data(
2314 annotations_typeArray, byte_i_ref,
2315 "const_value_index", THREAD);
2316
2317 log_debug(redefine, class, annotation)("const_value_index=%d", const_value_index);
2318 } break;
2319
2320 case 'e':
2321 {
2322 // for the above tag value, value.enum_const_value is right union field
2323
2324 if ((byte_i_ref + 4) > annotations_typeArray->length()) {
2325 // not enough room for a enum_const_value
2326 log_debug(redefine, class, annotation)("length() is too small for a enum_const_value");
2327 return false;
2328 }
2329
2330 u2 type_name_index = rewrite_cp_ref_in_annotation_data(
2331 annotations_typeArray, byte_i_ref,
2332 "type_name_index", THREAD);
2333
2334 u2 const_name_index = rewrite_cp_ref_in_annotation_data(
2335 annotations_typeArray, byte_i_ref,
2336 "const_name_index", THREAD);
2337
2338 log_debug(redefine, class, annotation)
2339 ("type_name_index=%d const_name_index=%d", type_name_index, const_name_index);
2340 } break;
2341
2342 case 'c':
2343 {
2344 // for the above tag value, value.class_info_index is right union field
2345
2346 if ((byte_i_ref + 2) > annotations_typeArray->length()) {
2347 // not enough room for a class_info_index
2348 log_debug(redefine, class, annotation)("length() is too small for a class_info_index");
2349 return false;
2350 }
2351
2352 u2 class_info_index = rewrite_cp_ref_in_annotation_data(
2353 annotations_typeArray, byte_i_ref,
2354 "class_info_index", THREAD);
2355
2356 log_debug(redefine, class, annotation)("class_info_index=%d", class_info_index);
2357 } break;
2358
2359 case '@':
2360 // For the above tag value, value.attr_value is the right union
2361 // field. This is a nested annotation.
2362 if (!rewrite_cp_refs_in_annotation_struct(annotations_typeArray,
2363 byte_i_ref, THREAD)) {
2364 // propagate failure back to caller
2365 return false;
2366 }
2367 break;
2368
2369 case JVM_SIGNATURE_ARRAY:
2370 {
2371 if ((byte_i_ref + 2) > annotations_typeArray->length()) {
2372 // not enough room for a num_values field
2373 log_debug(redefine, class, annotation)("length() is too small for a num_values field");
2374 return false;
2375 }
2376
2377 // For the above tag value, value.array_value is the right union
2378 // field. This is an array of nested element_value.
2379 u2 num_values = Bytes::get_Java_u2((address)
2380 annotations_typeArray->adr_at(byte_i_ref));
2381 byte_i_ref += 2;
2382 log_debug(redefine, class, annotation)("num_values=%d", num_values);
2383
2384 int calc_num_values = 0;
2385 for (; calc_num_values < num_values; calc_num_values++) {
2386 if (!rewrite_cp_refs_in_element_value(
2387 annotations_typeArray, byte_i_ref, THREAD)) {
2388 log_debug(redefine, class, annotation)("bad nested element_value at %d", calc_num_values);
2389 // propagate failure back to caller
2390 return false;
2391 }
2392 }
2393 assert(num_values == calc_num_values, "sanity check");
2394 } break;
2395
2396 default:
2397 log_debug(redefine, class, annotation)("bad tag=0x%x", tag);
2398 return false;
2399 } // end decode tag field
2400
2401 return true;
2402 } // end rewrite_cp_refs_in_element_value()
2403
2404
2405 // Rewrite constant pool references in a fields_annotations field.
2406 bool VM_RedefineClasses::rewrite_cp_refs_in_fields_annotations(
2407 InstanceKlass* scratch_class, TRAPS) {
2408
2409 Array<AnnotationArray*>* fields_annotations = scratch_class->fields_annotations();
2410
2411 if (fields_annotations == NULL || fields_annotations->length() == 0) {
2412 // no fields_annotations so nothing to do
2413 return true;
2414 }
2415
2416 log_debug(redefine, class, annotation)("fields_annotations length=%d", fields_annotations->length());
2417
2418 for (int i = 0; i < fields_annotations->length(); i++) {
2419 AnnotationArray* field_annotations = fields_annotations->at(i);
2420 if (field_annotations == NULL || field_annotations->length() == 0) {
2421 // this field does not have any annotations so skip it
2422 continue;
2423 }
2424
2425 int byte_i = 0; // byte index into field_annotations
2426 if (!rewrite_cp_refs_in_annotations_typeArray(field_annotations, byte_i,
2427 THREAD)) {
2428 log_debug(redefine, class, annotation)("bad field_annotations at %d", i);
2429 // propagate failure back to caller
2430 return false;
2431 }
2432 }
2433
2434 return true;
2435 } // end rewrite_cp_refs_in_fields_annotations()
2436
2437
2438 // Rewrite constant pool references in a methods_annotations field.
2439 bool VM_RedefineClasses::rewrite_cp_refs_in_methods_annotations(
2440 InstanceKlass* scratch_class, TRAPS) {
2441
2442 for (int i = 0; i < scratch_class->methods()->length(); i++) {
2443 Method* m = scratch_class->methods()->at(i);
2444 AnnotationArray* method_annotations = m->constMethod()->method_annotations();
2445
2446 if (method_annotations == NULL || method_annotations->length() == 0) {
2447 // this method does not have any annotations so skip it
2448 continue;
2449 }
2450
2451 int byte_i = 0; // byte index into method_annotations
2452 if (!rewrite_cp_refs_in_annotations_typeArray(method_annotations, byte_i,
2453 THREAD)) {
2454 log_debug(redefine, class, annotation)("bad method_annotations at %d", i);
2455 // propagate failure back to caller
2456 return false;
2457 }
2458 }
2459
2460 return true;
2461 } // end rewrite_cp_refs_in_methods_annotations()
2462
2463
2464 // Rewrite constant pool references in a methods_parameter_annotations
2465 // field. This "structure" is adapted from the
2466 // RuntimeVisibleParameterAnnotations_attribute described in section
2467 // 4.8.17 of the 2nd-edition of the VM spec:
2468 //
2469 // methods_parameter_annotations_typeArray {
2470 // u1 num_parameters;
2471 // {
2472 // u2 num_annotations;
2473 // annotation annotations[num_annotations];
2474 // } parameter_annotations[num_parameters];
2475 // }
2476 //
2477 bool VM_RedefineClasses::rewrite_cp_refs_in_methods_parameter_annotations(
2478 InstanceKlass* scratch_class, TRAPS) {
2479
2480 for (int i = 0; i < scratch_class->methods()->length(); i++) {
2481 Method* m = scratch_class->methods()->at(i);
2482 AnnotationArray* method_parameter_annotations = m->constMethod()->parameter_annotations();
2483 if (method_parameter_annotations == NULL
2484 || method_parameter_annotations->length() == 0) {
2485 // this method does not have any parameter annotations so skip it
2486 continue;
2487 }
2488
2489 if (method_parameter_annotations->length() < 1) {
2490 // not enough room for a num_parameters field
2491 log_debug(redefine, class, annotation)("length() is too small for a num_parameters field at %d", i);
2492 return false;
2493 }
2494
2495 int byte_i = 0; // byte index into method_parameter_annotations
2496
2497 u1 num_parameters = method_parameter_annotations->at(byte_i);
2498 byte_i++;
2499
2500 log_debug(redefine, class, annotation)("num_parameters=%d", num_parameters);
2501
2502 int calc_num_parameters = 0;
2503 for (; calc_num_parameters < num_parameters; calc_num_parameters++) {
2504 if (!rewrite_cp_refs_in_annotations_typeArray(
2505 method_parameter_annotations, byte_i, THREAD)) {
2506 log_debug(redefine, class, annotation)("bad method_parameter_annotations at %d", calc_num_parameters);
2507 // propagate failure back to caller
2508 return false;
2509 }
2510 }
2511 assert(num_parameters == calc_num_parameters, "sanity check");
2512 }
2513
2514 return true;
2515 } // end rewrite_cp_refs_in_methods_parameter_annotations()
2516
2517
2518 // Rewrite constant pool references in a methods_default_annotations
2519 // field. This "structure" is adapted from the AnnotationDefault_attribute
2520 // that is described in section 4.8.19 of the 2nd-edition of the VM spec:
2521 //
2522 // methods_default_annotations_typeArray {
2523 // element_value default_value;
2524 // }
2525 //
2526 bool VM_RedefineClasses::rewrite_cp_refs_in_methods_default_annotations(
2527 InstanceKlass* scratch_class, TRAPS) {
2528
2529 for (int i = 0; i < scratch_class->methods()->length(); i++) {
2530 Method* m = scratch_class->methods()->at(i);
2531 AnnotationArray* method_default_annotations = m->constMethod()->default_annotations();
2532 if (method_default_annotations == NULL
2533 || method_default_annotations->length() == 0) {
2534 // this method does not have any default annotations so skip it
2535 continue;
2536 }
2537
2538 int byte_i = 0; // byte index into method_default_annotations
2539
2540 if (!rewrite_cp_refs_in_element_value(
2541 method_default_annotations, byte_i, THREAD)) {
2542 log_debug(redefine, class, annotation)("bad default element_value at %d", i);
2543 // propagate failure back to caller
2544 return false;
2545 }
2546 }
2547
2548 return true;
2549 } // end rewrite_cp_refs_in_methods_default_annotations()
2550
2551
2552 // Rewrite constant pool references in a class_type_annotations field.
2553 bool VM_RedefineClasses::rewrite_cp_refs_in_class_type_annotations(
2554 InstanceKlass* scratch_class, TRAPS) {
2555
2556 AnnotationArray* class_type_annotations = scratch_class->class_type_annotations();
2557 if (class_type_annotations == NULL || class_type_annotations->length() == 0) {
2558 // no class_type_annotations so nothing to do
2559 return true;
2560 }
2561
2562 log_debug(redefine, class, annotation)("class_type_annotations length=%d", class_type_annotations->length());
2563
2564 int byte_i = 0; // byte index into class_type_annotations
2565 return rewrite_cp_refs_in_type_annotations_typeArray(class_type_annotations,
2566 byte_i, "ClassFile", THREAD);
2567 } // end rewrite_cp_refs_in_class_type_annotations()
2568
2569
2570 // Rewrite constant pool references in a fields_type_annotations field.
2571 bool VM_RedefineClasses::rewrite_cp_refs_in_fields_type_annotations(
2572 InstanceKlass* scratch_class, TRAPS) {
2573
2574 Array<AnnotationArray*>* fields_type_annotations = scratch_class->fields_type_annotations();
2575 if (fields_type_annotations == NULL || fields_type_annotations->length() == 0) {
2576 // no fields_type_annotations so nothing to do
2577 return true;
2578 }
2579
2580 log_debug(redefine, class, annotation)("fields_type_annotations length=%d", fields_type_annotations->length());
2581
2582 for (int i = 0; i < fields_type_annotations->length(); i++) {
2583 AnnotationArray* field_type_annotations = fields_type_annotations->at(i);
2584 if (field_type_annotations == NULL || field_type_annotations->length() == 0) {
2585 // this field does not have any annotations so skip it
2586 continue;
2587 }
2588
2589 int byte_i = 0; // byte index into field_type_annotations
2590 if (!rewrite_cp_refs_in_type_annotations_typeArray(field_type_annotations,
2591 byte_i, "field_info", THREAD)) {
2592 log_debug(redefine, class, annotation)("bad field_type_annotations at %d", i);
2593 // propagate failure back to caller
2594 return false;
2595 }
2596 }
2597
2598 return true;
2599 } // end rewrite_cp_refs_in_fields_type_annotations()
2600
2601
2602 // Rewrite constant pool references in a methods_type_annotations field.
2603 bool VM_RedefineClasses::rewrite_cp_refs_in_methods_type_annotations(
2604 InstanceKlass* scratch_class, TRAPS) {
2605
2606 for (int i = 0; i < scratch_class->methods()->length(); i++) {
2607 Method* m = scratch_class->methods()->at(i);
2608 AnnotationArray* method_type_annotations = m->constMethod()->type_annotations();
2609
2610 if (method_type_annotations == NULL || method_type_annotations->length() == 0) {
2611 // this method does not have any annotations so skip it
2612 continue;
2613 }
2614
2615 log_debug(redefine, class, annotation)("methods type_annotations length=%d", method_type_annotations->length());
2616
2617 int byte_i = 0; // byte index into method_type_annotations
2618 if (!rewrite_cp_refs_in_type_annotations_typeArray(method_type_annotations,
2619 byte_i, "method_info", THREAD)) {
2620 log_debug(redefine, class, annotation)("bad method_type_annotations at %d", i);
2621 // propagate failure back to caller
2622 return false;
2623 }
2624 }
2625
2626 return true;
2627 } // end rewrite_cp_refs_in_methods_type_annotations()
2628
2629
2630 // Rewrite constant pool references in a type_annotations
2631 // field. This "structure" is adapted from the
2632 // RuntimeVisibleTypeAnnotations_attribute described in
2633 // section 4.7.20 of the Java SE 8 Edition of the VM spec:
2634 //
2635 // type_annotations_typeArray {
2636 // u2 num_annotations;
2637 // type_annotation annotations[num_annotations];
2638 // }
2639 //
2640 bool VM_RedefineClasses::rewrite_cp_refs_in_type_annotations_typeArray(
2641 AnnotationArray* type_annotations_typeArray, int &byte_i_ref,
2642 const char * location_mesg, TRAPS) {
2643
2644 if ((byte_i_ref + 2) > type_annotations_typeArray->length()) {
2645 // not enough room for num_annotations field
2646 log_debug(redefine, class, annotation)("length() is too small for num_annotations field");
2647 return false;
2648 }
2649
2650 u2 num_annotations = Bytes::get_Java_u2((address)
2651 type_annotations_typeArray->adr_at(byte_i_ref));
2652 byte_i_ref += 2;
2653
2654 log_debug(redefine, class, annotation)("num_type_annotations=%d", num_annotations);
2655
2656 int calc_num_annotations = 0;
2657 for (; calc_num_annotations < num_annotations; calc_num_annotations++) {
2658 if (!rewrite_cp_refs_in_type_annotation_struct(type_annotations_typeArray,
2659 byte_i_ref, location_mesg, THREAD)) {
2660 log_debug(redefine, class, annotation)("bad type_annotation_struct at %d", calc_num_annotations);
2661 // propagate failure back to caller
2662 return false;
2663 }
2664 }
2665 assert(num_annotations == calc_num_annotations, "sanity check");
2666
2667 if (byte_i_ref != type_annotations_typeArray->length()) {
2668 log_debug(redefine, class, annotation)
2669 ("read wrong amount of bytes at end of processing type_annotations_typeArray (%d of %d bytes were read)",
2670 byte_i_ref, type_annotations_typeArray->length());
2671 return false;
2672 }
2673
2674 return true;
2675 } // end rewrite_cp_refs_in_type_annotations_typeArray()
2676
2677
2678 // Rewrite constant pool references in a type_annotation
2679 // field. This "structure" is adapted from the
2680 // RuntimeVisibleTypeAnnotations_attribute described in
2681 // section 4.7.20 of the Java SE 8 Edition of the VM spec:
2682 //
2683 // type_annotation {
2684 // u1 target_type;
2685 // union {
2686 // type_parameter_target;
2687 // supertype_target;
2688 // type_parameter_bound_target;
2689 // empty_target;
2690 // method_formal_parameter_target;
2691 // throws_target;
2692 // localvar_target;
2693 // catch_target;
2694 // offset_target;
2695 // type_argument_target;
2696 // } target_info;
2697 // type_path target_path;
2698 // annotation anno;
2699 // }
2700 //
2701 bool VM_RedefineClasses::rewrite_cp_refs_in_type_annotation_struct(
2702 AnnotationArray* type_annotations_typeArray, int &byte_i_ref,
2703 const char * location_mesg, TRAPS) {
2704
2705 if (!skip_type_annotation_target(type_annotations_typeArray,
2706 byte_i_ref, location_mesg, THREAD)) {
2707 return false;
2708 }
2709
2710 if (!skip_type_annotation_type_path(type_annotations_typeArray,
2711 byte_i_ref, THREAD)) {
2712 return false;
2713 }
2714
2715 if (!rewrite_cp_refs_in_annotation_struct(type_annotations_typeArray,
2716 byte_i_ref, THREAD)) {
2717 return false;
2718 }
2719
2720 return true;
2721 } // end rewrite_cp_refs_in_type_annotation_struct()
2722
2723
2724 // Read, verify and skip over the target_type and target_info part
2725 // so that rewriting can continue in the later parts of the struct.
2726 //
2727 // u1 target_type;
2728 // union {
2729 // type_parameter_target;
2730 // supertype_target;
2731 // type_parameter_bound_target;
2732 // empty_target;
2733 // method_formal_parameter_target;
2734 // throws_target;
2735 // localvar_target;
2736 // catch_target;
2737 // offset_target;
2738 // type_argument_target;
2739 // } target_info;
2740 //
2741 bool VM_RedefineClasses::skip_type_annotation_target(
2742 AnnotationArray* type_annotations_typeArray, int &byte_i_ref,
2743 const char * location_mesg, TRAPS) {
2744
2745 if ((byte_i_ref + 1) > type_annotations_typeArray->length()) {
2746 // not enough room for a target_type let alone the rest of a type_annotation
2747 log_debug(redefine, class, annotation)("length() is too small for a target_type");
2748 return false;
2749 }
2750
2751 u1 target_type = type_annotations_typeArray->at(byte_i_ref);
2752 byte_i_ref += 1;
2753 log_debug(redefine, class, annotation)("target_type=0x%.2x", target_type);
2754 log_debug(redefine, class, annotation)("location=%s", location_mesg);
2755
2756 // Skip over target_info
2757 switch (target_type) {
2758 case 0x00:
2759 // kind: type parameter declaration of generic class or interface
2760 // location: ClassFile
2761 case 0x01:
2762 // kind: type parameter declaration of generic method or constructor
2763 // location: method_info
2764
2765 {
2766 // struct:
2767 // type_parameter_target {
2768 // u1 type_parameter_index;
2769 // }
2770 //
2771 if ((byte_i_ref + 1) > type_annotations_typeArray->length()) {
2772 log_debug(redefine, class, annotation)("length() is too small for a type_parameter_target");
2773 return false;
2774 }
2775
2776 u1 type_parameter_index = type_annotations_typeArray->at(byte_i_ref);
2777 byte_i_ref += 1;
2778
2779 log_debug(redefine, class, annotation)("type_parameter_target: type_parameter_index=%d", type_parameter_index);
2780 } break;
2781
2782 case 0x10:
2783 // kind: type in extends clause of class or interface declaration
2784 // (including the direct superclass of an unsafe anonymous class declaration),
2785 // or in implements clause of interface declaration
2786 // location: ClassFile
2787
2788 {
2789 // struct:
2790 // supertype_target {
2791 // u2 supertype_index;
2792 // }
2793 //
2794 if ((byte_i_ref + 2) > type_annotations_typeArray->length()) {
2795 log_debug(redefine, class, annotation)("length() is too small for a supertype_target");
2796 return false;
2797 }
2798
2799 u2 supertype_index = Bytes::get_Java_u2((address)
2800 type_annotations_typeArray->adr_at(byte_i_ref));
2801 byte_i_ref += 2;
2802
2803 log_debug(redefine, class, annotation)("supertype_target: supertype_index=%d", supertype_index);
2804 } break;
2805
2806 case 0x11:
2807 // kind: type in bound of type parameter declaration of generic class or interface
2808 // location: ClassFile
2809 case 0x12:
2810 // kind: type in bound of type parameter declaration of generic method or constructor
2811 // location: method_info
2812
2813 {
2814 // struct:
2815 // type_parameter_bound_target {
2816 // u1 type_parameter_index;
2817 // u1 bound_index;
2818 // }
2819 //
2820 if ((byte_i_ref + 2) > type_annotations_typeArray->length()) {
2821 log_debug(redefine, class, annotation)("length() is too small for a type_parameter_bound_target");
2822 return false;
2823 }
2824
2825 u1 type_parameter_index = type_annotations_typeArray->at(byte_i_ref);
2826 byte_i_ref += 1;
2827 u1 bound_index = type_annotations_typeArray->at(byte_i_ref);
2828 byte_i_ref += 1;
2829
2830 log_debug(redefine, class, annotation)
2831 ("type_parameter_bound_target: type_parameter_index=%d, bound_index=%d", type_parameter_index, bound_index);
2832 } break;
2833
2834 case 0x13:
2835 // kind: type in field declaration
2836 // location: field_info
2837 case 0x14:
2838 // kind: return type of method, or type of newly constructed object
2839 // location: method_info
2840 case 0x15:
2841 // kind: receiver type of method or constructor
2842 // location: method_info
2843
2844 {
2845 // struct:
2846 // empty_target {
2847 // }
2848 //
2849 log_debug(redefine, class, annotation)("empty_target");
2850 } break;
2851
2852 case 0x16:
2853 // kind: type in formal parameter declaration of method, constructor, or lambda expression
2854 // location: method_info
2855
2856 {
2857 // struct:
2858 // formal_parameter_target {
2859 // u1 formal_parameter_index;
2860 // }
2861 //
2862 if ((byte_i_ref + 1) > type_annotations_typeArray->length()) {
2863 log_debug(redefine, class, annotation)("length() is too small for a formal_parameter_target");
2864 return false;
2865 }
2866
2867 u1 formal_parameter_index = type_annotations_typeArray->at(byte_i_ref);
2868 byte_i_ref += 1;
2869
2870 log_debug(redefine, class, annotation)
2871 ("formal_parameter_target: formal_parameter_index=%d", formal_parameter_index);
2872 } break;
2873
2874 case 0x17:
2875 // kind: type in throws clause of method or constructor
2876 // location: method_info
2877
2878 {
2879 // struct:
2880 // throws_target {
2881 // u2 throws_type_index
2882 // }
2883 //
2884 if ((byte_i_ref + 2) > type_annotations_typeArray->length()) {
2885 log_debug(redefine, class, annotation)("length() is too small for a throws_target");
2886 return false;
2887 }
2888
2889 u2 throws_type_index = Bytes::get_Java_u2((address)
2890 type_annotations_typeArray->adr_at(byte_i_ref));
2891 byte_i_ref += 2;
2892
2893 log_debug(redefine, class, annotation)("throws_target: throws_type_index=%d", throws_type_index);
2894 } break;
2895
2896 case 0x40:
2897 // kind: type in local variable declaration
2898 // location: Code
2899 case 0x41:
2900 // kind: type in resource variable declaration
2901 // location: Code
2902
2903 {
2904 // struct:
2905 // localvar_target {
2906 // u2 table_length;
2907 // struct {
2908 // u2 start_pc;
2909 // u2 length;
2910 // u2 index;
2911 // } table[table_length];
2912 // }
2913 //
2914 if ((byte_i_ref + 2) > type_annotations_typeArray->length()) {
2915 // not enough room for a table_length let alone the rest of a localvar_target
2916 log_debug(redefine, class, annotation)("length() is too small for a localvar_target table_length");
2917 return false;
2918 }
2919
2920 u2 table_length = Bytes::get_Java_u2((address)
2921 type_annotations_typeArray->adr_at(byte_i_ref));
2922 byte_i_ref += 2;
2923
2924 log_debug(redefine, class, annotation)("localvar_target: table_length=%d", table_length);
2925
2926 int table_struct_size = 2 + 2 + 2; // 3 u2 variables per table entry
2927 int table_size = table_length * table_struct_size;
2928
2929 if ((byte_i_ref + table_size) > type_annotations_typeArray->length()) {
2930 // not enough room for a table
2931 log_debug(redefine, class, annotation)("length() is too small for a table array of length %d", table_length);
2932 return false;
2933 }
2934
2935 // Skip over table
2936 byte_i_ref += table_size;
2937 } break;
2938
2939 case 0x42:
2940 // kind: type in exception parameter declaration
2941 // location: Code
2942
2943 {
2944 // struct:
2945 // catch_target {
2946 // u2 exception_table_index;
2947 // }
2948 //
2949 if ((byte_i_ref + 2) > type_annotations_typeArray->length()) {
2950 log_debug(redefine, class, annotation)("length() is too small for a catch_target");
2951 return false;
2952 }
2953
2954 u2 exception_table_index = Bytes::get_Java_u2((address)
2955 type_annotations_typeArray->adr_at(byte_i_ref));
2956 byte_i_ref += 2;
2957
2958 log_debug(redefine, class, annotation)("catch_target: exception_table_index=%d", exception_table_index);
2959 } break;
2960
2961 case 0x43:
2962 // kind: type in instanceof expression
2963 // location: Code
2964 case 0x44:
2965 // kind: type in new expression
2966 // location: Code
2967 case 0x45:
2968 // kind: type in method reference expression using ::new
2969 // location: Code
2970 case 0x46:
2971 // kind: type in method reference expression using ::Identifier
2972 // location: Code
2973
2974 {
2975 // struct:
2976 // offset_target {
2977 // u2 offset;
2978 // }
2979 //
2980 if ((byte_i_ref + 2) > type_annotations_typeArray->length()) {
2981 log_debug(redefine, class, annotation)("length() is too small for a offset_target");
2982 return false;
2983 }
2984
2985 u2 offset = Bytes::get_Java_u2((address)
2986 type_annotations_typeArray->adr_at(byte_i_ref));
2987 byte_i_ref += 2;
2988
2989 log_debug(redefine, class, annotation)("offset_target: offset=%d", offset);
2990 } break;
2991
2992 case 0x47:
2993 // kind: type in cast expression
2994 // location: Code
2995 case 0x48:
2996 // kind: type argument for generic constructor in new expression or
2997 // explicit constructor invocation statement
2998 // location: Code
2999 case 0x49:
3000 // kind: type argument for generic method in method invocation expression
3001 // location: Code
3002 case 0x4A:
3003 // kind: type argument for generic constructor in method reference expression using ::new
3004 // location: Code
3005 case 0x4B:
3006 // kind: type argument for generic method in method reference expression using ::Identifier
3007 // location: Code
3008
3009 {
3010 // struct:
3011 // type_argument_target {
3012 // u2 offset;
3013 // u1 type_argument_index;
3014 // }
3015 //
3016 if ((byte_i_ref + 3) > type_annotations_typeArray->length()) {
3017 log_debug(redefine, class, annotation)("length() is too small for a type_argument_target");
3018 return false;
3019 }
3020
3021 u2 offset = Bytes::get_Java_u2((address)
3022 type_annotations_typeArray->adr_at(byte_i_ref));
3023 byte_i_ref += 2;
3024 u1 type_argument_index = type_annotations_typeArray->at(byte_i_ref);
3025 byte_i_ref += 1;
3026
3027 log_debug(redefine, class, annotation)
3028 ("type_argument_target: offset=%d, type_argument_index=%d", offset, type_argument_index);
3029 } break;
3030
3031 default:
3032 log_debug(redefine, class, annotation)("unknown target_type");
3033 #ifdef ASSERT
3034 ShouldNotReachHere();
3035 #endif
3036 return false;
3037 }
3038
3039 return true;
3040 } // end skip_type_annotation_target()
3041
3042
3043 // Read, verify and skip over the type_path part so that rewriting
3044 // can continue in the later parts of the struct.
3045 //
3046 // type_path {
3047 // u1 path_length;
3048 // {
3049 // u1 type_path_kind;
3050 // u1 type_argument_index;
3051 // } path[path_length];
3052 // }
3053 //
3054 bool VM_RedefineClasses::skip_type_annotation_type_path(
3055 AnnotationArray* type_annotations_typeArray, int &byte_i_ref, TRAPS) {
3056
3057 if ((byte_i_ref + 1) > type_annotations_typeArray->length()) {
3058 // not enough room for a path_length let alone the rest of the type_path
3059 log_debug(redefine, class, annotation)("length() is too small for a type_path");
3060 return false;
3061 }
3062
3063 u1 path_length = type_annotations_typeArray->at(byte_i_ref);
3064 byte_i_ref += 1;
3065
3066 log_debug(redefine, class, annotation)("type_path: path_length=%d", path_length);
3067
3068 int calc_path_length = 0;
3069 for (; calc_path_length < path_length; calc_path_length++) {
3070 if ((byte_i_ref + 1 + 1) > type_annotations_typeArray->length()) {
3071 // not enough room for a path
3072 log_debug(redefine, class, annotation)
3073 ("length() is too small for path entry %d of %d", calc_path_length, path_length);
3074 return false;
3075 }
3076
3077 u1 type_path_kind = type_annotations_typeArray->at(byte_i_ref);
3078 byte_i_ref += 1;
3079 u1 type_argument_index = type_annotations_typeArray->at(byte_i_ref);
3080 byte_i_ref += 1;
3081
3082 log_debug(redefine, class, annotation)
3083 ("type_path: path[%d]: type_path_kind=%d, type_argument_index=%d",
3084 calc_path_length, type_path_kind, type_argument_index);
3085
3086 if (type_path_kind > 3 || (type_path_kind != 3 && type_argument_index != 0)) {
3087 // not enough room for a path
3088 log_debug(redefine, class, annotation)("inconsistent type_path values");
3089 return false;
3090 }
3091 }
3092 assert(path_length == calc_path_length, "sanity check");
3093
3094 return true;
3095 } // end skip_type_annotation_type_path()
3096
3097
3098 // Rewrite constant pool references in the method's stackmap table.
3099 // These "structures" are adapted from the StackMapTable_attribute that
3100 // is described in section 4.8.4 of the 6.0 version of the VM spec
3101 // (dated 2005.10.26):
3102 // file:///net/quincunx.sfbay/export/gbracha/ClassFile-Java6.pdf
3103 //
3104 // stack_map {
3105 // u2 number_of_entries;
3106 // stack_map_frame entries[number_of_entries];
3107 // }
3108 //
3109 void VM_RedefineClasses::rewrite_cp_refs_in_stack_map_table(
3110 const methodHandle& method, TRAPS) {
3111
3112 if (!method->has_stackmap_table()) {
3113 return;
3114 }
3115
3116 AnnotationArray* stackmap_data = method->stackmap_data();
3117 address stackmap_p = (address)stackmap_data->adr_at(0);
3118 address stackmap_end = stackmap_p + stackmap_data->length();
3119
3120 assert(stackmap_p + 2 <= stackmap_end, "no room for number_of_entries");
3121 u2 number_of_entries = Bytes::get_Java_u2(stackmap_p);
3122 stackmap_p += 2;
3123
3124 log_debug(redefine, class, stackmap)("number_of_entries=%u", number_of_entries);
3125
3126 // walk through each stack_map_frame
3127 u2 calc_number_of_entries = 0;
3128 for (; calc_number_of_entries < number_of_entries; calc_number_of_entries++) {
3129 // The stack_map_frame structure is a u1 frame_type followed by
3130 // 0 or more bytes of data:
3131 //
3132 // union stack_map_frame {
3133 // same_frame;
3134 // same_locals_1_stack_item_frame;
3135 // same_locals_1_stack_item_frame_extended;
3136 // chop_frame;
3137 // same_frame_extended;
3138 // append_frame;
3139 // full_frame;
3140 // }
3141
3142 assert(stackmap_p + 1 <= stackmap_end, "no room for frame_type");
3143 u1 frame_type = *stackmap_p;
3144 stackmap_p++;
3145
3146 // same_frame {
3147 // u1 frame_type = SAME; /* 0-63 */
3148 // }
3149 if (frame_type <= 63) {
3150 // nothing more to do for same_frame
3151 }
3152
3153 // same_locals_1_stack_item_frame {
3154 // u1 frame_type = SAME_LOCALS_1_STACK_ITEM; /* 64-127 */
3155 // verification_type_info stack[1];
3156 // }
3157 else if (frame_type >= 64 && frame_type <= 127) {
3158 rewrite_cp_refs_in_verification_type_info(stackmap_p, stackmap_end,
3159 calc_number_of_entries, frame_type, THREAD);
3160 }
3161
3162 // reserved for future use
3163 else if (frame_type >= 128 && frame_type <= 246) {
3164 // nothing more to do for reserved frame_types
3165 }
3166
3167 // same_locals_1_stack_item_frame_extended {
3168 // u1 frame_type = SAME_LOCALS_1_STACK_ITEM_EXTENDED; /* 247 */
3169 // u2 offset_delta;
3170 // verification_type_info stack[1];
3171 // }
3172 else if (frame_type == 247) {
3173 stackmap_p += 2;
3174 rewrite_cp_refs_in_verification_type_info(stackmap_p, stackmap_end,
3175 calc_number_of_entries, frame_type, THREAD);
3176 }
3177
3178 // chop_frame {
3179 // u1 frame_type = CHOP; /* 248-250 */
3180 // u2 offset_delta;
3181 // }
3182 else if (frame_type >= 248 && frame_type <= 250) {
3183 stackmap_p += 2;
3184 }
3185
3186 // same_frame_extended {
3187 // u1 frame_type = SAME_FRAME_EXTENDED; /* 251*/
3188 // u2 offset_delta;
3189 // }
3190 else if (frame_type == 251) {
3191 stackmap_p += 2;
3192 }
3193
3194 // append_frame {
3195 // u1 frame_type = APPEND; /* 252-254 */
3196 // u2 offset_delta;
3197 // verification_type_info locals[frame_type - 251];
3198 // }
3199 else if (frame_type >= 252 && frame_type <= 254) {
3200 assert(stackmap_p + 2 <= stackmap_end,
3201 "no room for offset_delta");
3202 stackmap_p += 2;
3203 u1 len = frame_type - 251;
3204 for (u1 i = 0; i < len; i++) {
3205 rewrite_cp_refs_in_verification_type_info(stackmap_p, stackmap_end,
3206 calc_number_of_entries, frame_type, THREAD);
3207 }
3208 }
3209
3210 // full_frame {
3211 // u1 frame_type = FULL_FRAME; /* 255 */
3212 // u2 offset_delta;
3213 // u2 number_of_locals;
3214 // verification_type_info locals[number_of_locals];
3215 // u2 number_of_stack_items;
3216 // verification_type_info stack[number_of_stack_items];
3217 // }
3218 else if (frame_type == 255) {
3219 assert(stackmap_p + 2 + 2 <= stackmap_end,
3220 "no room for smallest full_frame");
3221 stackmap_p += 2;
3222
3223 u2 number_of_locals = Bytes::get_Java_u2(stackmap_p);
3224 stackmap_p += 2;
3225
3226 for (u2 locals_i = 0; locals_i < number_of_locals; locals_i++) {
3227 rewrite_cp_refs_in_verification_type_info(stackmap_p, stackmap_end,
3228 calc_number_of_entries, frame_type, THREAD);
3229 }
3230
3231 // Use the largest size for the number_of_stack_items, but only get
3232 // the right number of bytes.
3233 u2 number_of_stack_items = Bytes::get_Java_u2(stackmap_p);
3234 stackmap_p += 2;
3235
3236 for (u2 stack_i = 0; stack_i < number_of_stack_items; stack_i++) {
3237 rewrite_cp_refs_in_verification_type_info(stackmap_p, stackmap_end,
3238 calc_number_of_entries, frame_type, THREAD);
3239 }
3240 }
3241 } // end while there is a stack_map_frame
3242 assert(number_of_entries == calc_number_of_entries, "sanity check");
3243 } // end rewrite_cp_refs_in_stack_map_table()
3244
3245
3246 // Rewrite constant pool references in the verification type info
3247 // portion of the method's stackmap table. These "structures" are
3248 // adapted from the StackMapTable_attribute that is described in
3249 // section 4.8.4 of the 6.0 version of the VM spec (dated 2005.10.26):
3250 // file:///net/quincunx.sfbay/export/gbracha/ClassFile-Java6.pdf
3251 //
3252 // The verification_type_info structure is a u1 tag followed by 0 or
3253 // more bytes of data:
3254 //
3255 // union verification_type_info {
3256 // Top_variable_info;
3257 // Integer_variable_info;
3258 // Float_variable_info;
3259 // Long_variable_info;
3260 // Double_variable_info;
3261 // Null_variable_info;
3262 // UninitializedThis_variable_info;
3263 // Object_variable_info;
3264 // Uninitialized_variable_info;
3265 // }
3266 //
3267 void VM_RedefineClasses::rewrite_cp_refs_in_verification_type_info(
3268 address& stackmap_p_ref, address stackmap_end, u2 frame_i,
3269 u1 frame_type, TRAPS) {
3270
3271 assert(stackmap_p_ref + 1 <= stackmap_end, "no room for tag");
3272 u1 tag = *stackmap_p_ref;
3273 stackmap_p_ref++;
3274
3275 switch (tag) {
3276 // Top_variable_info {
3277 // u1 tag = ITEM_Top; /* 0 */
3278 // }
3279 // verificationType.hpp has zero as ITEM_Bogus instead of ITEM_Top
3280 case 0: // fall through
3281
3282 // Integer_variable_info {
3283 // u1 tag = ITEM_Integer; /* 1 */
3284 // }
3285 case ITEM_Integer: // fall through
3286
3287 // Float_variable_info {
3288 // u1 tag = ITEM_Float; /* 2 */
3289 // }
3290 case ITEM_Float: // fall through
3291
3292 // Double_variable_info {
3293 // u1 tag = ITEM_Double; /* 3 */
3294 // }
3295 case ITEM_Double: // fall through
3296
3297 // Long_variable_info {
3298 // u1 tag = ITEM_Long; /* 4 */
3299 // }
3300 case ITEM_Long: // fall through
3301
3302 // Null_variable_info {
3303 // u1 tag = ITEM_Null; /* 5 */
3304 // }
3305 case ITEM_Null: // fall through
3306
3307 // UninitializedThis_variable_info {
3308 // u1 tag = ITEM_UninitializedThis; /* 6 */
3309 // }
3310 case ITEM_UninitializedThis:
3311 // nothing more to do for the above tag types
3312 break;
3313
3314 // Object_variable_info {
3315 // u1 tag = ITEM_Object; /* 7 */
3316 // u2 cpool_index;
3317 // }
3318 case ITEM_Object:
3319 {
3320 assert(stackmap_p_ref + 2 <= stackmap_end, "no room for cpool_index");
3321 u2 cpool_index = Bytes::get_Java_u2(stackmap_p_ref);
3322 u2 new_cp_index = find_new_index(cpool_index);
3323 if (new_cp_index != 0) {
3324 log_debug(redefine, class, stackmap)("mapped old cpool_index=%d", cpool_index);
3325 Bytes::put_Java_u2(stackmap_p_ref, new_cp_index);
3326 cpool_index = new_cp_index;
3327 }
3328 stackmap_p_ref += 2;
3329
3330 log_debug(redefine, class, stackmap)
3331 ("frame_i=%u, frame_type=%u, cpool_index=%d", frame_i, frame_type, cpool_index);
3332 } break;
3333
3334 // Uninitialized_variable_info {
3335 // u1 tag = ITEM_Uninitialized; /* 8 */
3336 // u2 offset;
3337 // }
3338 case ITEM_Uninitialized:
3339 assert(stackmap_p_ref + 2 <= stackmap_end, "no room for offset");
3340 stackmap_p_ref += 2;
3341 break;
3342
3343 default:
3344 log_debug(redefine, class, stackmap)("frame_i=%u, frame_type=%u, bad tag=0x%x", frame_i, frame_type, tag);
3345 ShouldNotReachHere();
3346 break;
3347 } // end switch (tag)
3348 } // end rewrite_cp_refs_in_verification_type_info()
3349
3350
3351 // Change the constant pool associated with klass scratch_class to
3352 // scratch_cp. If shrink is true, then scratch_cp_length elements
3353 // are copied from scratch_cp to a smaller constant pool and the
3354 // smaller constant pool is associated with scratch_class.
3355 void VM_RedefineClasses::set_new_constant_pool(
3356 ClassLoaderData* loader_data,
3357 InstanceKlass* scratch_class, constantPoolHandle scratch_cp,
3358 int scratch_cp_length, TRAPS) {
3359 assert(scratch_cp->length() >= scratch_cp_length, "sanity check");
3360
3361 // scratch_cp is a merged constant pool and has enough space for a
3362 // worst case merge situation. We want to associate the minimum
3363 // sized constant pool with the klass to save space.
3364 ConstantPool* cp = ConstantPool::allocate(loader_data, scratch_cp_length, CHECK);
3365 constantPoolHandle smaller_cp(THREAD, cp);
3366
3367 // preserve version() value in the smaller copy
3368 int version = scratch_cp->version();
3369 assert(version != 0, "sanity check");
3370 smaller_cp->set_version(version);
3371
3372 // attach klass to new constant pool
3373 // reference to the cp holder is needed for copy_operands()
3374 smaller_cp->set_pool_holder(scratch_class);
3375
3376 if (scratch_cp->has_dynamic_constant()) {
3377 smaller_cp->set_has_dynamic_constant();
3378 }
3379
3380 scratch_cp->copy_cp_to(1, scratch_cp_length - 1, smaller_cp, 1, THREAD);
3381 if (HAS_PENDING_EXCEPTION) {
3382 // Exception is handled in the caller
3383 loader_data->add_to_deallocate_list(smaller_cp());
3384 return;
3385 }
3386 scratch_cp = smaller_cp;
3387
3388 // attach new constant pool to klass
3389 scratch_class->set_constants(scratch_cp());
3390 scratch_cp->initialize_unresolved_klasses(loader_data, CHECK);
3391
3392 int i; // for portability
3393
3394 // update each field in klass to use new constant pool indices as needed
3395 for (JavaFieldStream fs(scratch_class); !fs.done(); fs.next()) {
3396 jshort cur_index = fs.name_index();
3397 jshort new_index = find_new_index(cur_index);
3398 if (new_index != 0) {
3399 log_trace(redefine, class, constantpool)("field-name_index change: %d to %d", cur_index, new_index);
3400 fs.set_name_index(new_index);
3401 }
3402 cur_index = fs.signature_index();
3403 new_index = find_new_index(cur_index);
3404 if (new_index != 0) {
3405 log_trace(redefine, class, constantpool)("field-signature_index change: %d to %d", cur_index, new_index);
3406 fs.set_signature_index(new_index);
3407 }
3408 cur_index = fs.initval_index();
3409 new_index = find_new_index(cur_index);
3410 if (new_index != 0) {
3411 log_trace(redefine, class, constantpool)("field-initval_index change: %d to %d", cur_index, new_index);
3412 fs.set_initval_index(new_index);
3413 }
3414 cur_index = fs.generic_signature_index();
3415 new_index = find_new_index(cur_index);
3416 if (new_index != 0) {
3417 log_trace(redefine, class, constantpool)("field-generic_signature change: %d to %d", cur_index, new_index);
3418 fs.set_generic_signature_index(new_index);
3419 }
3420 } // end for each field
3421
3422 // Update constant pool indices in the inner classes info to use
3423 // new constant indices as needed. The inner classes info is a
3424 // quadruple:
3425 // (inner_class_info, outer_class_info, inner_name, inner_access_flags)
3426 InnerClassesIterator iter(scratch_class);
3427 for (; !iter.done(); iter.next()) {
3428 int cur_index = iter.inner_class_info_index();
3429 if (cur_index == 0) {
3430 continue; // JVM spec. allows null inner class refs so skip it
3431 }
3432 int new_index = find_new_index(cur_index);
3433 if (new_index != 0) {
3434 log_trace(redefine, class, constantpool)("inner_class_info change: %d to %d", cur_index, new_index);
3435 iter.set_inner_class_info_index(new_index);
3436 }
3437 cur_index = iter.outer_class_info_index();
3438 new_index = find_new_index(cur_index);
3439 if (new_index != 0) {
3440 log_trace(redefine, class, constantpool)("outer_class_info change: %d to %d", cur_index, new_index);
3441 iter.set_outer_class_info_index(new_index);
3442 }
3443 cur_index = iter.inner_name_index();
3444 new_index = find_new_index(cur_index);
3445 if (new_index != 0) {
3446 log_trace(redefine, class, constantpool)("inner_name change: %d to %d", cur_index, new_index);
3447 iter.set_inner_name_index(new_index);
3448 }
3449 } // end for each inner class
3450
3451 // Attach each method in klass to the new constant pool and update
3452 // to use new constant pool indices as needed:
3453 Array<Method*>* methods = scratch_class->methods();
3454 for (i = methods->length() - 1; i >= 0; i--) {
3455 methodHandle method(THREAD, methods->at(i));
3456 method->set_constants(scratch_cp());
3457
3458 int new_index = find_new_index(method->name_index());
3459 if (new_index != 0) {
3460 log_trace(redefine, class, constantpool)
3461 ("method-name_index change: %d to %d", method->name_index(), new_index);
3462 method->set_name_index(new_index);
3463 }
3464 new_index = find_new_index(method->signature_index());
3465 if (new_index != 0) {
3466 log_trace(redefine, class, constantpool)
3467 ("method-signature_index change: %d to %d", method->signature_index(), new_index);
3468 method->set_signature_index(new_index);
3469 }
3470 new_index = find_new_index(method->generic_signature_index());
3471 if (new_index != 0) {
3472 log_trace(redefine, class, constantpool)
3473 ("method-generic_signature_index change: %d to %d", method->generic_signature_index(), new_index);
3474 method->set_generic_signature_index(new_index);
3475 }
3476
3477 // Update constant pool indices in the method's checked exception
3478 // table to use new constant indices as needed.
3479 int cext_length = method->checked_exceptions_length();
3480 if (cext_length > 0) {
3481 CheckedExceptionElement * cext_table =
3482 method->checked_exceptions_start();
3483 for (int j = 0; j < cext_length; j++) {
3484 int cur_index = cext_table[j].class_cp_index;
3485 int new_index = find_new_index(cur_index);
3486 if (new_index != 0) {
3487 log_trace(redefine, class, constantpool)("cext-class_cp_index change: %d to %d", cur_index, new_index);
3488 cext_table[j].class_cp_index = (u2)new_index;
3489 }
3490 } // end for each checked exception table entry
3491 } // end if there are checked exception table entries
3492
3493 // Update each catch type index in the method's exception table
3494 // to use new constant pool indices as needed. The exception table
3495 // holds quadruple entries of the form:
3496 // (beg_bci, end_bci, handler_bci, klass_index)
3497
3498 ExceptionTable ex_table(method());
3499 int ext_length = ex_table.length();
3500
3501 for (int j = 0; j < ext_length; j ++) {
3502 int cur_index = ex_table.catch_type_index(j);
3503 int new_index = find_new_index(cur_index);
3504 if (new_index != 0) {
3505 log_trace(redefine, class, constantpool)("ext-klass_index change: %d to %d", cur_index, new_index);
3506 ex_table.set_catch_type_index(j, new_index);
3507 }
3508 } // end for each exception table entry
3509
3510 // Update constant pool indices in the method's local variable
3511 // table to use new constant indices as needed. The local variable
3512 // table hold sextuple entries of the form:
3513 // (start_pc, length, name_index, descriptor_index, signature_index, slot)
3514 int lvt_length = method->localvariable_table_length();
3515 if (lvt_length > 0) {
3516 LocalVariableTableElement * lv_table =
3517 method->localvariable_table_start();
3518 for (int j = 0; j < lvt_length; j++) {
3519 int cur_index = lv_table[j].name_cp_index;
3520 int new_index = find_new_index(cur_index);
3521 if (new_index != 0) {
3522 log_trace(redefine, class, constantpool)("lvt-name_cp_index change: %d to %d", cur_index, new_index);
3523 lv_table[j].name_cp_index = (u2)new_index;
3524 }
3525 cur_index = lv_table[j].descriptor_cp_index;
3526 new_index = find_new_index(cur_index);
3527 if (new_index != 0) {
3528 log_trace(redefine, class, constantpool)("lvt-descriptor_cp_index change: %d to %d", cur_index, new_index);
3529 lv_table[j].descriptor_cp_index = (u2)new_index;
3530 }
3531 cur_index = lv_table[j].signature_cp_index;
3532 new_index = find_new_index(cur_index);
3533 if (new_index != 0) {
3534 log_trace(redefine, class, constantpool)("lvt-signature_cp_index change: %d to %d", cur_index, new_index);
3535 lv_table[j].signature_cp_index = (u2)new_index;
3536 }
3537 } // end for each local variable table entry
3538 } // end if there are local variable table entries
3539
3540 rewrite_cp_refs_in_stack_map_table(method, THREAD);
3541 } // end for each method
3542 } // end set_new_constant_pool()
3543
3544
3545 // Unevolving classes may point to methods of the_class directly
3546 // from their constant pool caches, itables, and/or vtables. We
3547 // use the ClassLoaderDataGraph::classes_do() facility and this helper
3548 // to fix up these pointers. MethodData also points to old methods and
3549 // must be cleaned.
3550
3551 // Adjust cpools and vtables closure
3552 void VM_RedefineClasses::AdjustAndCleanMetadata::do_klass(Klass* k) {
3553
3554 // This is a very busy routine. We don't want too much tracing
3555 // printed out.
3556 bool trace_name_printed = false;
3557
3558 // If the class being redefined is java.lang.Object, we need to fix all
3559 // array class vtables also
3560 if (k->is_array_klass() && _has_redefined_Object) {
3561 k->vtable().adjust_method_entries(&trace_name_printed);
3562
3563 } else if (k->is_instance_klass()) {
3564 HandleMark hm(_thread);
3565 InstanceKlass *ik = InstanceKlass::cast(k);
3566
3567 // Clean MethodData of this class's methods so they don't refer to
3568 // old methods that are no longer running.
3569 Array<Method*>* methods = ik->methods();
3570 int num_methods = methods->length();
3571 for (int index = 0; index < num_methods; ++index) {
3572 if (methods->at(index)->method_data() != NULL) {
3573 methods->at(index)->method_data()->clean_weak_method_links();
3574 }
3575 }
3576
3577 // HotSpot specific optimization! HotSpot does not currently
3578 // support delegation from the bootstrap class loader to a
3579 // user-defined class loader. This means that if the bootstrap
3580 // class loader is the initiating class loader, then it will also
3581 // be the defining class loader. This also means that classes
3582 // loaded by the bootstrap class loader cannot refer to classes
3583 // loaded by a user-defined class loader. Note: a user-defined
3584 // class loader can delegate to the bootstrap class loader.
3585 //
3586 // If the current class being redefined has a user-defined class
3587 // loader as its defining class loader, then we can skip all
3588 // classes loaded by the bootstrap class loader.
3589 if (!_has_null_class_loader && ik->class_loader() == NULL) {
3590 return;
3591 }
3592
3593 // Adjust all vtables, default methods and itables, to clean out old methods.
3594 ResourceMark rm(_thread);
3595 if (ik->vtable_length() > 0) {
3596 ik->vtable().adjust_method_entries(&trace_name_printed);
3597 ik->adjust_default_methods(&trace_name_printed);
3598 }
3599
3600 if (ik->itable_length() > 0) {
3601 ik->itable().adjust_method_entries(&trace_name_printed);
3602 }
3603
3604 // The constant pools in other classes (other_cp) can refer to
3605 // old methods. We have to update method information in
3606 // other_cp's cache. If other_cp has a previous version, then we
3607 // have to repeat the process for each previous version. The
3608 // constant pool cache holds the Method*s for non-virtual
3609 // methods and for virtual, final methods.
3610 //
3611 // Special case: if the current class being redefined, then new_cp
3612 // has already been attached to the_class and old_cp has already
3613 // been added as a previous version. The new_cp doesn't have any
3614 // cached references to old methods so it doesn't need to be
3615 // updated. We can simply start with the previous version(s) in
3616 // that case.
3617 ConstantPoolCache* cp_cache;
3618
3619 if (!ik->is_being_redefined()) {
3620 // this klass' constant pool cache may need adjustment
3621 ConstantPool* other_cp = ik->constants();
3622 cp_cache = other_cp->cache();
3623 if (cp_cache != NULL) {
3624 cp_cache->adjust_method_entries(&trace_name_printed);
3625 }
3626 }
3627
3628 // the previous versions' constant pool caches may need adjustment
3629 for (InstanceKlass* pv_node = ik->previous_versions();
3630 pv_node != NULL;
3631 pv_node = pv_node->previous_versions()) {
3632 cp_cache = pv_node->constants()->cache();
3633 if (cp_cache != NULL) {
3634 cp_cache->adjust_method_entries(&trace_name_printed);
3635 }
3636 }
3637 }
3638 }
3639
3640 void VM_RedefineClasses::update_jmethod_ids(Thread* thread) {
3641 for (int j = 0; j < _matching_methods_length; ++j) {
3642 Method* old_method = _matching_old_methods[j];
3643 jmethodID jmid = old_method->find_jmethod_id_or_null();
3644 if (jmid != NULL) {
3645 // There is a jmethodID, change it to point to the new method
3646 methodHandle new_method_h(thread, _matching_new_methods[j]);
3647 Method::change_method_associated_with_jmethod_id(jmid, new_method_h());
3648 assert(Method::resolve_jmethod_id(jmid) == _matching_new_methods[j],
3649 "should be replaced");
3650 }
3651 }
3652 }
3653
3654 int VM_RedefineClasses::check_methods_and_mark_as_obsolete() {
3655 int emcp_method_count = 0;
3656 int obsolete_count = 0;
3657 int old_index = 0;
3658 for (int j = 0; j < _matching_methods_length; ++j, ++old_index) {
3659 Method* old_method = _matching_old_methods[j];
3660 Method* new_method = _matching_new_methods[j];
3661 Method* old_array_method;
3662
3663 // Maintain an old_index into the _old_methods array by skipping
3664 // deleted methods
3665 while ((old_array_method = _old_methods->at(old_index)) != old_method) {
3666 ++old_index;
3667 }
3668
3669 if (MethodComparator::methods_EMCP(old_method, new_method)) {
3670 // The EMCP definition from JSR-163 requires the bytecodes to be
3671 // the same with the exception of constant pool indices which may
3672 // differ. However, the constants referred to by those indices
3673 // must be the same.
3674 //
3675 // We use methods_EMCP() for comparison since constant pool
3676 // merging can remove duplicate constant pool entries that were
3677 // present in the old method and removed from the rewritten new
3678 // method. A faster binary comparison function would consider the
3679 // old and new methods to be different when they are actually
3680 // EMCP.
3681 //
3682 // The old and new methods are EMCP and you would think that we
3683 // could get rid of one of them here and now and save some space.
3684 // However, the concept of EMCP only considers the bytecodes and
3685 // the constant pool entries in the comparison. Other things,
3686 // e.g., the line number table (LNT) or the local variable table
3687 // (LVT) don't count in the comparison. So the new (and EMCP)
3688 // method can have a new LNT that we need so we can't just
3689 // overwrite the new method with the old method.
3690 //
3691 // When this routine is called, we have already attached the new
3692 // methods to the_class so the old methods are effectively
3693 // overwritten. However, if an old method is still executing,
3694 // then the old method cannot be collected until sometime after
3695 // the old method call has returned. So the overwriting of old
3696 // methods by new methods will save us space except for those
3697 // (hopefully few) old methods that are still executing.
3698 //
3699 // A method refers to a ConstMethod* and this presents another
3700 // possible avenue to space savings. The ConstMethod* in the
3701 // new method contains possibly new attributes (LNT, LVT, etc).
3702 // At first glance, it seems possible to save space by replacing
3703 // the ConstMethod* in the old method with the ConstMethod*
3704 // from the new method. The old and new methods would share the
3705 // same ConstMethod* and we would save the space occupied by
3706 // the old ConstMethod*. However, the ConstMethod* contains
3707 // a back reference to the containing method. Sharing the
3708 // ConstMethod* between two methods could lead to confusion in
3709 // the code that uses the back reference. This would lead to
3710 // brittle code that could be broken in non-obvious ways now or
3711 // in the future.
3712 //
3713 // Another possibility is to copy the ConstMethod* from the new
3714 // method to the old method and then overwrite the new method with
3715 // the old method. Since the ConstMethod* contains the bytecodes
3716 // for the method embedded in the oop, this option would change
3717 // the bytecodes out from under any threads executing the old
3718 // method and make the thread's bcp invalid. Since EMCP requires
3719 // that the bytecodes be the same modulo constant pool indices, it
3720 // is straight forward to compute the correct new bcp in the new
3721 // ConstMethod* from the old bcp in the old ConstMethod*. The
3722 // time consuming part would be searching all the frames in all
3723 // of the threads to find all of the calls to the old method.
3724 //
3725 // It looks like we will have to live with the limited savings
3726 // that we get from effectively overwriting the old methods
3727 // when the new methods are attached to the_class.
3728
3729 // Count number of methods that are EMCP. The method will be marked
3730 // old but not obsolete if it is EMCP.
3731 emcp_method_count++;
3732
3733 // An EMCP method is _not_ obsolete. An obsolete method has a
3734 // different jmethodID than the current method. An EMCP method
3735 // has the same jmethodID as the current method. Having the
3736 // same jmethodID for all EMCP versions of a method allows for
3737 // a consistent view of the EMCP methods regardless of which
3738 // EMCP method you happen to have in hand. For example, a
3739 // breakpoint set in one EMCP method will work for all EMCP
3740 // versions of the method including the current one.
3741 } else {
3742 // mark obsolete methods as such
3743 old_method->set_is_obsolete();
3744 obsolete_count++;
3745
3746 // obsolete methods need a unique idnum so they become new entries in
3747 // the jmethodID cache in InstanceKlass
3748 assert(old_method->method_idnum() == new_method->method_idnum(), "must match");
3749 u2 num = InstanceKlass::cast(_the_class)->next_method_idnum();
3750 if (num != ConstMethod::UNSET_IDNUM) {
3751 old_method->set_method_idnum(num);
3752 }
3753
3754 // With tracing we try not to "yack" too much. The position of
3755 // this trace assumes there are fewer obsolete methods than
3756 // EMCP methods.
3757 if (log_is_enabled(Trace, redefine, class, obsolete, mark)) {
3758 ResourceMark rm;
3759 log_trace(redefine, class, obsolete, mark)
3760 ("mark %s(%s) as obsolete", old_method->name()->as_C_string(), old_method->signature()->as_C_string());
3761 }
3762 }
3763 old_method->set_is_old();
3764 }
3765 for (int i = 0; i < _deleted_methods_length; ++i) {
3766 Method* old_method = _deleted_methods[i];
3767
3768 assert(!old_method->has_vtable_index(),
3769 "cannot delete methods with vtable entries");;
3770
3771 // Mark all deleted methods as old, obsolete and deleted
3772 old_method->set_is_deleted();
3773 old_method->set_is_old();
3774 old_method->set_is_obsolete();
3775 ++obsolete_count;
3776 // With tracing we try not to "yack" too much. The position of
3777 // this trace assumes there are fewer obsolete methods than
3778 // EMCP methods.
3779 if (log_is_enabled(Trace, redefine, class, obsolete, mark)) {
3780 ResourceMark rm;
3781 log_trace(redefine, class, obsolete, mark)
3782 ("mark deleted %s(%s) as obsolete", old_method->name()->as_C_string(), old_method->signature()->as_C_string());
3783 }
3784 }
3785 assert((emcp_method_count + obsolete_count) == _old_methods->length(),
3786 "sanity check");
3787 log_trace(redefine, class, obsolete, mark)("EMCP_cnt=%d, obsolete_cnt=%d", emcp_method_count, obsolete_count);
3788 return emcp_method_count;
3789 }
3790
3791 // This internal class transfers the native function registration from old methods
3792 // to new methods. It is designed to handle both the simple case of unchanged
3793 // native methods and the complex cases of native method prefixes being added and/or
3794 // removed.
3795 // It expects only to be used during the VM_RedefineClasses op (a safepoint).
3796 //
3797 // This class is used after the new methods have been installed in "the_class".
3798 //
3799 // So, for example, the following must be handled. Where 'm' is a method and
3800 // a number followed by an underscore is a prefix.
3801 //
3802 // Old Name New Name
3803 // Simple transfer to new method m -> m
3804 // Add prefix m -> 1_m
3805 // Remove prefix 1_m -> m
3806 // Simultaneous add of prefixes m -> 3_2_1_m
3807 // Simultaneous removal of prefixes 3_2_1_m -> m
3808 // Simultaneous add and remove 1_m -> 2_m
3809 // Same, caused by prefix removal only 3_2_1_m -> 3_2_m
3810 //
3811 class TransferNativeFunctionRegistration {
3812 private:
3813 InstanceKlass* the_class;
3814 int prefix_count;
3815 char** prefixes;
3816
3817 // Recursively search the binary tree of possibly prefixed method names.
3818 // Iteration could be used if all agents were well behaved. Full tree walk is
3819 // more resilent to agents not cleaning up intermediate methods.
3820 // Branch at each depth in the binary tree is:
3821 // (1) without the prefix.
3822 // (2) with the prefix.
3823 // where 'prefix' is the prefix at that 'depth' (first prefix, second prefix,...)
3824 Method* search_prefix_name_space(int depth, char* name_str, size_t name_len,
3825 Symbol* signature) {
3826 TempNewSymbol name_symbol = SymbolTable::probe(name_str, (int)name_len);
3827 if (name_symbol != NULL) {
3828 Method* method = the_class->lookup_method(name_symbol, signature);
3829 if (method != NULL) {
3830 // Even if prefixed, intermediate methods must exist.
3831 if (method->is_native()) {
3832 // Wahoo, we found a (possibly prefixed) version of the method, return it.
3833 return method;
3834 }
3835 if (depth < prefix_count) {
3836 // Try applying further prefixes (other than this one).
3837 method = search_prefix_name_space(depth+1, name_str, name_len, signature);
3838 if (method != NULL) {
3839 return method; // found
3840 }
3841
3842 // Try adding this prefix to the method name and see if it matches
3843 // another method name.
3844 char* prefix = prefixes[depth];
3845 size_t prefix_len = strlen(prefix);
3846 size_t trial_len = name_len + prefix_len;
3847 char* trial_name_str = NEW_RESOURCE_ARRAY(char, trial_len + 1);
3848 strcpy(trial_name_str, prefix);
3849 strcat(trial_name_str, name_str);
3850 method = search_prefix_name_space(depth+1, trial_name_str, trial_len,
3851 signature);
3852 if (method != NULL) {
3853 // If found along this branch, it was prefixed, mark as such
3854 method->set_is_prefixed_native();
3855 return method; // found
3856 }
3857 }
3858 }
3859 }
3860 return NULL; // This whole branch bore nothing
3861 }
3862
3863 // Return the method name with old prefixes stripped away.
3864 char* method_name_without_prefixes(Method* method) {
3865 Symbol* name = method->name();
3866 char* name_str = name->as_utf8();
3867
3868 // Old prefixing may be defunct, strip prefixes, if any.
3869 for (int i = prefix_count-1; i >= 0; i--) {
3870 char* prefix = prefixes[i];
3871 size_t prefix_len = strlen(prefix);
3872 if (strncmp(prefix, name_str, prefix_len) == 0) {
3873 name_str += prefix_len;
3874 }
3875 }
3876 return name_str;
3877 }
3878
3879 // Strip any prefixes off the old native method, then try to find a
3880 // (possibly prefixed) new native that matches it.
3881 Method* strip_and_search_for_new_native(Method* method) {
3882 ResourceMark rm;
3883 char* name_str = method_name_without_prefixes(method);
3884 return search_prefix_name_space(0, name_str, strlen(name_str),
3885 method->signature());
3886 }
3887
3888 public:
3889
3890 // Construct a native method transfer processor for this class.
3891 TransferNativeFunctionRegistration(InstanceKlass* _the_class) {
3892 assert(SafepointSynchronize::is_at_safepoint(), "sanity check");
3893
3894 the_class = _the_class;
3895 prefixes = JvmtiExport::get_all_native_method_prefixes(&prefix_count);
3896 }
3897
3898 // Attempt to transfer any of the old or deleted methods that are native
3899 void transfer_registrations(Method** old_methods, int methods_length) {
3900 for (int j = 0; j < methods_length; j++) {
3901 Method* old_method = old_methods[j];
3902
3903 if (old_method->is_native() && old_method->has_native_function()) {
3904 Method* new_method = strip_and_search_for_new_native(old_method);
3905 if (new_method != NULL) {
3906 // Actually set the native function in the new method.
3907 // Redefine does not send events (except CFLH), certainly not this
3908 // behind the scenes re-registration.
3909 new_method->set_native_function(old_method->native_function(),
3910 !Method::native_bind_event_is_interesting);
3911 }
3912 }
3913 }
3914 }
3915 };
3916
3917 // Don't lose the association between a native method and its JNI function.
3918 void VM_RedefineClasses::transfer_old_native_function_registrations(InstanceKlass* the_class) {
3919 TransferNativeFunctionRegistration transfer(the_class);
3920 transfer.transfer_registrations(_deleted_methods, _deleted_methods_length);
3921 transfer.transfer_registrations(_matching_old_methods, _matching_methods_length);
3922 }
3923
3924 // Deoptimize all compiled code that depends on this class.
3925 //
3926 // If the can_redefine_classes capability is obtained in the onload
3927 // phase then the compiler has recorded all dependencies from startup.
3928 // In that case we need only deoptimize and throw away all compiled code
3929 // that depends on the class.
3930 //
3931 // If can_redefine_classes is obtained sometime after the onload
3932 // phase then the dependency information may be incomplete. In that case
3933 // the first call to RedefineClasses causes all compiled code to be
3934 // thrown away. As can_redefine_classes has been obtained then
3935 // all future compilations will record dependencies so second and
3936 // subsequent calls to RedefineClasses need only throw away code
3937 // that depends on the class.
3938 //
3939
3940 // First step is to walk the code cache for each class redefined and mark
3941 // dependent methods. Wait until all classes are processed to deoptimize everything.
3942 void VM_RedefineClasses::mark_dependent_code(InstanceKlass* ik) {
3943 assert_locked_or_safepoint(Compile_lock);
3944
3945 // All dependencies have been recorded from startup or this is a second or
3946 // subsequent use of RedefineClasses
3947 if (JvmtiExport::all_dependencies_are_recorded()) {
3948 CodeCache::mark_for_evol_deoptimization(ik);
3949 }
3950 }
3951
3952 void VM_RedefineClasses::flush_dependent_code() {
3953 assert(SafepointSynchronize::is_at_safepoint(), "sanity check");
3954
3955 bool deopt_needed;
3956
3957 // This is the first redefinition, mark all the nmethods for deoptimization
3958 if (!JvmtiExport::all_dependencies_are_recorded()) {
3959 log_debug(redefine, class, nmethod)("Marked all nmethods for deopt");
3960 CodeCache::mark_all_nmethods_for_evol_deoptimization();
3961 deopt_needed = true;
3962 } else {
3963 int deopt = CodeCache::mark_dependents_for_evol_deoptimization();
3964 log_debug(redefine, class, nmethod)("Marked %d dependent nmethods for deopt", deopt);
3965 deopt_needed = (deopt != 0);
3966 }
3967
3968 if (deopt_needed) {
3969 CodeCache::flush_evol_dependents();
3970 }
3971
3972 // From now on we know that the dependency information is complete
3973 JvmtiExport::set_all_dependencies_are_recorded(true);
3974 }
3975
3976 void VM_RedefineClasses::compute_added_deleted_matching_methods() {
3977 Method* old_method;
3978 Method* new_method;
3979
3980 _matching_old_methods = NEW_RESOURCE_ARRAY(Method*, _old_methods->length());
3981 _matching_new_methods = NEW_RESOURCE_ARRAY(Method*, _old_methods->length());
3982 _added_methods = NEW_RESOURCE_ARRAY(Method*, _new_methods->length());
3983 _deleted_methods = NEW_RESOURCE_ARRAY(Method*, _old_methods->length());
3984
3985 _matching_methods_length = 0;
3986 _deleted_methods_length = 0;
3987 _added_methods_length = 0;
3988
3989 int nj = 0;
3990 int oj = 0;
3991 while (true) {
3992 if (oj >= _old_methods->length()) {
3993 if (nj >= _new_methods->length()) {
3994 break; // we've looked at everything, done
3995 }
3996 // New method at the end
3997 new_method = _new_methods->at(nj);
3998 _added_methods[_added_methods_length++] = new_method;
3999 ++nj;
4000 } else if (nj >= _new_methods->length()) {
4001 // Old method, at the end, is deleted
4002 old_method = _old_methods->at(oj);
4003 _deleted_methods[_deleted_methods_length++] = old_method;
4004 ++oj;
4005 } else {
4006 old_method = _old_methods->at(oj);
4007 new_method = _new_methods->at(nj);
4008 if (old_method->name() == new_method->name()) {
4009 if (old_method->signature() == new_method->signature()) {
4010 _matching_old_methods[_matching_methods_length ] = old_method;
4011 _matching_new_methods[_matching_methods_length++] = new_method;
4012 ++nj;
4013 ++oj;
4014 } else {
4015 // added overloaded have already been moved to the end,
4016 // so this is a deleted overloaded method
4017 _deleted_methods[_deleted_methods_length++] = old_method;
4018 ++oj;
4019 }
4020 } else { // names don't match
4021 if (old_method->name()->fast_compare(new_method->name()) > 0) {
4022 // new method
4023 _added_methods[_added_methods_length++] = new_method;
4024 ++nj;
4025 } else {
4026 // deleted method
4027 _deleted_methods[_deleted_methods_length++] = old_method;
4028 ++oj;
4029 }
4030 }
4031 }
4032 }
4033 assert(_matching_methods_length + _deleted_methods_length == _old_methods->length(), "sanity");
4034 assert(_matching_methods_length + _added_methods_length == _new_methods->length(), "sanity");
4035 }
4036
4037
4038 void VM_RedefineClasses::swap_annotations(InstanceKlass* the_class,
4039 InstanceKlass* scratch_class) {
4040 // Swap annotation fields values
4041 Annotations* old_annotations = the_class->annotations();
4042 the_class->set_annotations(scratch_class->annotations());
4043 scratch_class->set_annotations(old_annotations);
4044 }
4045
4046
4047 // Install the redefinition of a class:
4048 // - house keeping (flushing breakpoints and caches, deoptimizing
4049 // dependent compiled code)
4050 // - replacing parts in the_class with parts from scratch_class
4051 // - adding a weak reference to track the obsolete but interesting
4052 // parts of the_class
4053 // - adjusting constant pool caches and vtables in other classes
4054 // that refer to methods in the_class. These adjustments use the
4055 // ClassLoaderDataGraph::classes_do() facility which only allows
4056 // a helper method to be specified. The interesting parameters
4057 // that we would like to pass to the helper method are saved in
4058 // static global fields in the VM operation.
4059 void VM_RedefineClasses::redefine_single_class(jclass the_jclass,
4060 InstanceKlass* scratch_class, TRAPS) {
4061
4062 HandleMark hm(THREAD); // make sure handles from this call are freed
4063
4064 if (log_is_enabled(Info, redefine, class, timer)) {
4065 _timer_rsc_phase1.start();
4066 }
4067
4068 InstanceKlass* the_class = get_ik(the_jclass);
4069
4070 // Set some flags to control and optimize adjusting method entries
4071 _has_redefined_Object |= the_class == SystemDictionary::Object_klass();
4072 _has_null_class_loader |= the_class->class_loader() == NULL;
4073
4074 // Remove all breakpoints in methods of this class
4075 JvmtiBreakpoints& jvmti_breakpoints = JvmtiCurrentBreakpoints::get_jvmti_breakpoints();
4076 jvmti_breakpoints.clearall_in_class_at_safepoint(the_class);
4077
4078 // Mark all compiled code that depends on this class
4079 mark_dependent_code(the_class);
4080
4081 _old_methods = the_class->methods();
4082 _new_methods = scratch_class->methods();
4083 _the_class = the_class;
4084 compute_added_deleted_matching_methods();
4085 update_jmethod_ids(THREAD);
4086
4087 _any_class_has_resolved_methods = the_class->has_resolved_methods() || _any_class_has_resolved_methods;
4088
4089 // Attach new constant pool to the original klass. The original
4090 // klass still refers to the old constant pool (for now).
4091 scratch_class->constants()->set_pool_holder(the_class);
4092
4093 #if 0
4094 // In theory, with constant pool merging in place we should be able
4095 // to save space by using the new, merged constant pool in place of
4096 // the old constant pool(s). By "pool(s)" I mean the constant pool in
4097 // the klass version we are replacing now and any constant pool(s) in
4098 // previous versions of klass. Nice theory, doesn't work in practice.
4099 // When this code is enabled, even simple programs throw NullPointer
4100 // exceptions. I'm guessing that this is caused by some constant pool
4101 // cache difference between the new, merged constant pool and the
4102 // constant pool that was just being used by the klass. I'm keeping
4103 // this code around to archive the idea, but the code has to remain
4104 // disabled for now.
4105
4106 // Attach each old method to the new constant pool. This can be
4107 // done here since we are past the bytecode verification and
4108 // constant pool optimization phases.
4109 for (int i = _old_methods->length() - 1; i >= 0; i--) {
4110 Method* method = _old_methods->at(i);
4111 method->set_constants(scratch_class->constants());
4112 }
4113
4114 // NOTE: this doesn't work because you can redefine the same class in two
4115 // threads, each getting their own constant pool data appended to the
4116 // original constant pool. In order for the new methods to work when they
4117 // become old methods, they need to keep their updated copy of the constant pool.
4118
4119 {
4120 // walk all previous versions of the klass
4121 InstanceKlass *ik = the_class;
4122 PreviousVersionWalker pvw(ik);
4123 do {
4124 ik = pvw.next_previous_version();
4125 if (ik != NULL) {
4126
4127 // attach previous version of klass to the new constant pool
4128 ik->set_constants(scratch_class->constants());
4129
4130 // Attach each method in the previous version of klass to the
4131 // new constant pool
4132 Array<Method*>* prev_methods = ik->methods();
4133 for (int i = prev_methods->length() - 1; i >= 0; i--) {
4134 Method* method = prev_methods->at(i);
4135 method->set_constants(scratch_class->constants());
4136 }
4137 }
4138 } while (ik != NULL);
4139 }
4140 #endif
4141
4142 // Replace methods and constantpool
4143 the_class->set_methods(_new_methods);
4144 scratch_class->set_methods(_old_methods); // To prevent potential GCing of the old methods,
4145 // and to be able to undo operation easily.
4146
4147 Array<int>* old_ordering = the_class->method_ordering();
4148 the_class->set_method_ordering(scratch_class->method_ordering());
4149 scratch_class->set_method_ordering(old_ordering);
4150
4151 ConstantPool* old_constants = the_class->constants();
4152 the_class->set_constants(scratch_class->constants());
4153 scratch_class->set_constants(old_constants); // See the previous comment.
4154 #if 0
4155 // We are swapping the guts of "the new class" with the guts of "the
4156 // class". Since the old constant pool has just been attached to "the
4157 // new class", it seems logical to set the pool holder in the old
4158 // constant pool also. However, doing this will change the observable
4159 // class hierarchy for any old methods that are still executing. A
4160 // method can query the identity of its "holder" and this query uses
4161 // the method's constant pool link to find the holder. The change in
4162 // holding class from "the class" to "the new class" can confuse
4163 // things.
4164 //
4165 // Setting the old constant pool's holder will also cause
4166 // verification done during vtable initialization below to fail.
4167 // During vtable initialization, the vtable's class is verified to be
4168 // a subtype of the method's holder. The vtable's class is "the
4169 // class" and the method's holder is gotten from the constant pool
4170 // link in the method itself. For "the class"'s directly implemented
4171 // methods, the method holder is "the class" itself (as gotten from
4172 // the new constant pool). The check works fine in this case. The
4173 // check also works fine for methods inherited from super classes.
4174 //
4175 // Miranda methods are a little more complicated. A miranda method is
4176 // provided by an interface when the class implementing the interface
4177 // does not provide its own method. These interfaces are implemented
4178 // internally as an InstanceKlass. These special instanceKlasses
4179 // share the constant pool of the class that "implements" the
4180 // interface. By sharing the constant pool, the method holder of a
4181 // miranda method is the class that "implements" the interface. In a
4182 // non-redefine situation, the subtype check works fine. However, if
4183 // the old constant pool's pool holder is modified, then the check
4184 // fails because there is no class hierarchy relationship between the
4185 // vtable's class and "the new class".
4186
4187 old_constants->set_pool_holder(scratch_class());
4188 #endif
4189
4190 // track number of methods that are EMCP for add_previous_version() call below
4191 int emcp_method_count = check_methods_and_mark_as_obsolete();
4192 transfer_old_native_function_registrations(the_class);
4193
4194 // The class file bytes from before any retransformable agents mucked
4195 // with them was cached on the scratch class, move to the_class.
4196 // Note: we still want to do this if nothing needed caching since it
4197 // should get cleared in the_class too.
4198 if (the_class->get_cached_class_file() == 0) {
4199 // the_class doesn't have a cache yet so copy it
4200 the_class->set_cached_class_file(scratch_class->get_cached_class_file());
4201 }
4202 else if (scratch_class->get_cached_class_file() !=
4203 the_class->get_cached_class_file()) {
4204 // The same class can be present twice in the scratch classes list or there
4205 // are multiple concurrent RetransformClasses calls on different threads.
4206 // In such cases we have to deallocate scratch_class cached_class_file.
4207 os::free(scratch_class->get_cached_class_file());
4208 }
4209
4210 // NULL out in scratch class to not delete twice. The class to be redefined
4211 // always owns these bytes.
4212 scratch_class->set_cached_class_file(NULL);
4213
4214 // Replace inner_classes
4215 Array<u2>* old_inner_classes = the_class->inner_classes();
4216 the_class->set_inner_classes(scratch_class->inner_classes());
4217 scratch_class->set_inner_classes(old_inner_classes);
4218
4219 // Initialize the vtable and interface table after
4220 // methods have been rewritten
4221 // no exception should happen here since we explicitly
4222 // do not check loader constraints.
4223 // compare_and_normalize_class_versions has already checked:
4224 // - classloaders unchanged, signatures unchanged
4225 // - all instanceKlasses for redefined classes reused & contents updated
4226 the_class->vtable().initialize_vtable(false, THREAD);
4227 the_class->itable().initialize_itable(false, THREAD);
4228 assert(!HAS_PENDING_EXCEPTION || (THREAD->pending_exception()->is_a(SystemDictionary::ThreadDeath_klass())), "redefine exception");
4229
4230 // Leave arrays of jmethodIDs and itable index cache unchanged
4231
4232 // Copy the "source file name" attribute from new class version
4233 the_class->set_source_file_name_index(
4234 scratch_class->source_file_name_index());
4235
4236 // Copy the "source debug extension" attribute from new class version
4237 the_class->set_source_debug_extension(
4238 scratch_class->source_debug_extension(),
4239 scratch_class->source_debug_extension() == NULL ? 0 :
4240 (int)strlen(scratch_class->source_debug_extension()));
4241
4242 // Use of javac -g could be different in the old and the new
4243 if (scratch_class->access_flags().has_localvariable_table() !=
4244 the_class->access_flags().has_localvariable_table()) {
4245
4246 AccessFlags flags = the_class->access_flags();
4247 if (scratch_class->access_flags().has_localvariable_table()) {
4248 flags.set_has_localvariable_table();
4249 } else {
4250 flags.clear_has_localvariable_table();
4251 }
4252 the_class->set_access_flags(flags);
4253 }
4254
4255 swap_annotations(the_class, scratch_class);
4256
4257 // Replace minor version number of class file
4258 u2 old_minor_version = the_class->minor_version();
4259 the_class->set_minor_version(scratch_class->minor_version());
4260 scratch_class->set_minor_version(old_minor_version);
4261
4262 // Replace major version number of class file
4263 u2 old_major_version = the_class->major_version();
4264 the_class->set_major_version(scratch_class->major_version());
4265 scratch_class->set_major_version(old_major_version);
4266
4267 // Replace CP indexes for class and name+type of enclosing method
4268 u2 old_class_idx = the_class->enclosing_method_class_index();
4269 u2 old_method_idx = the_class->enclosing_method_method_index();
4270 the_class->set_enclosing_method_indices(
4271 scratch_class->enclosing_method_class_index(),
4272 scratch_class->enclosing_method_method_index());
4273 scratch_class->set_enclosing_method_indices(old_class_idx, old_method_idx);
4274
4275 // Replace fingerprint data
4276 the_class->set_has_passed_fingerprint_check(scratch_class->has_passed_fingerprint_check());
4277 the_class->store_fingerprint(scratch_class->get_stored_fingerprint());
4278
4279 the_class->set_has_been_redefined();
4280
4281 if (!the_class->should_be_initialized()) {
4282 // Class was already initialized, so AOT has only seen the original version.
4283 // We need to let AOT look at it again.
4284 AOTLoader::load_for_klass(the_class, THREAD);
4285 }
4286
4287 // keep track of previous versions of this class
4288 the_class->add_previous_version(scratch_class, emcp_method_count);
4289
4290 _timer_rsc_phase1.stop();
4291 if (log_is_enabled(Info, redefine, class, timer)) {
4292 _timer_rsc_phase2.start();
4293 }
4294
4295 if (the_class->oop_map_cache() != NULL) {
4296 // Flush references to any obsolete methods from the oop map cache
4297 // so that obsolete methods are not pinned.
4298 the_class->oop_map_cache()->flush_obsolete_entries();
4299 }
4300
4301 increment_class_counter((InstanceKlass *)the_class, THREAD);
4302
4303 if (EventClassRedefinition::is_enabled()) {
4304 EventClassRedefinition event;
4305 event.set_classModificationCount(java_lang_Class::classRedefinedCount(the_class->java_mirror()));
4306 event.set_redefinedClass(the_class);
4307 event.set_redefinitionId(_id);
4308 event.commit();
4309 }
4310
4311 {
4312 ResourceMark rm(THREAD);
4313 // increment the classRedefinedCount field in the_class and in any
4314 // direct and indirect subclasses of the_class
4315 log_info(redefine, class, load)
4316 ("redefined name=%s, count=%d (avail_mem=" UINT64_FORMAT "K)",
4317 the_class->external_name(), java_lang_Class::classRedefinedCount(the_class->java_mirror()), os::available_memory() >> 10);
4318 Events::log_redefinition(THREAD, "redefined class name=%s, count=%d",
4319 the_class->external_name(),
4320 java_lang_Class::classRedefinedCount(the_class->java_mirror()));
4321
4322 }
4323 _timer_rsc_phase2.stop();
4324
4325 } // end redefine_single_class()
4326
4327
4328 // Increment the classRedefinedCount field in the specific InstanceKlass
4329 // and in all direct and indirect subclasses.
4330 void VM_RedefineClasses::increment_class_counter(InstanceKlass *ik, TRAPS) {
4331 oop class_mirror = ik->java_mirror();
4332 Klass* class_oop = java_lang_Class::as_Klass(class_mirror);
4333 int new_count = java_lang_Class::classRedefinedCount(class_mirror) + 1;
4334 java_lang_Class::set_classRedefinedCount(class_mirror, new_count);
4335
4336 if (class_oop != _the_class) {
4337 // _the_class count is printed at end of redefine_single_class()
4338 log_debug(redefine, class, subclass)("updated count in subclass=%s to %d", ik->external_name(), new_count);
4339 }
4340
4341 for (Klass *subk = ik->subklass(); subk != NULL;
4342 subk = subk->next_sibling()) {
4343 if (subk->is_instance_klass()) {
4344 // Only update instanceKlasses
4345 InstanceKlass *subik = InstanceKlass::cast(subk);
4346 // recursively do subclasses of the current subclass
4347 increment_class_counter(subik, THREAD);
4348 }
4349 }
4350 }
4351
4352 void VM_RedefineClasses::CheckClass::do_klass(Klass* k) {
4353 bool no_old_methods = true; // be optimistic
4354
4355 // Both array and instance classes have vtables.
4356 // a vtable should never contain old or obsolete methods
4357 ResourceMark rm(_thread);
4358 if (k->vtable_length() > 0 &&
4359 !k->vtable().check_no_old_or_obsolete_entries()) {
4360 if (log_is_enabled(Trace, redefine, class, obsolete, metadata)) {
4361 log_trace(redefine, class, obsolete, metadata)
4362 ("klassVtable::check_no_old_or_obsolete_entries failure -- OLD or OBSOLETE method found -- class: %s",
4363 k->signature_name());
4364 k->vtable().dump_vtable();
4365 }
4366 no_old_methods = false;
4367 }
4368
4369 if (k->is_instance_klass()) {
4370 HandleMark hm(_thread);
4371 InstanceKlass *ik = InstanceKlass::cast(k);
4372
4373 // an itable should never contain old or obsolete methods
4374 if (ik->itable_length() > 0 &&
4375 !ik->itable().check_no_old_or_obsolete_entries()) {
4376 if (log_is_enabled(Trace, redefine, class, obsolete, metadata)) {
4377 log_trace(redefine, class, obsolete, metadata)
4378 ("klassItable::check_no_old_or_obsolete_entries failure -- OLD or OBSOLETE method found -- class: %s",
4379 ik->signature_name());
4380 ik->itable().dump_itable();
4381 }
4382 no_old_methods = false;
4383 }
4384
4385 // the constant pool cache should never contain non-deleted old or obsolete methods
4386 if (ik->constants() != NULL &&
4387 ik->constants()->cache() != NULL &&
4388 !ik->constants()->cache()->check_no_old_or_obsolete_entries()) {
4389 if (log_is_enabled(Trace, redefine, class, obsolete, metadata)) {
4390 log_trace(redefine, class, obsolete, metadata)
4391 ("cp-cache::check_no_old_or_obsolete_entries failure -- OLD or OBSOLETE method found -- class: %s",
4392 ik->signature_name());
4393 ik->constants()->cache()->dump_cache();
4394 }
4395 no_old_methods = false;
4396 }
4397 }
4398
4399 // print and fail guarantee if old methods are found.
4400 if (!no_old_methods) {
4401 if (log_is_enabled(Trace, redefine, class, obsolete, metadata)) {
4402 dump_methods();
4403 } else {
4404 log_trace(redefine, class)("Use the '-Xlog:redefine+class*:' option "
4405 "to see more info about the following guarantee() failure.");
4406 }
4407 guarantee(false, "OLD and/or OBSOLETE method(s) found");
4408 }
4409 }
4410
4411 u8 VM_RedefineClasses::next_id() {
4412 while (true) {
4413 u8 id = _id_counter;
4414 u8 next_id = id + 1;
4415 u8 result = Atomic::cmpxchg(&_id_counter, id, next_id);
4416 if (result == id) {
4417 return next_id;
4418 }
4419 }
4420 }
4421
4422 void VM_RedefineClasses::dump_methods() {
4423 int j;
4424 log_trace(redefine, class, dump)("_old_methods --");
4425 for (j = 0; j < _old_methods->length(); ++j) {
4426 LogStreamHandle(Trace, redefine, class, dump) log_stream;
4427 Method* m = _old_methods->at(j);
4428 log_stream.print("%4d (%5d) ", j, m->vtable_index());
4429 m->access_flags().print_on(&log_stream);
4430 log_stream.print(" -- ");
4431 m->print_name(&log_stream);
4432 log_stream.cr();
4433 }
4434 log_trace(redefine, class, dump)("_new_methods --");
4435 for (j = 0; j < _new_methods->length(); ++j) {
4436 LogStreamHandle(Trace, redefine, class, dump) log_stream;
4437 Method* m = _new_methods->at(j);
4438 log_stream.print("%4d (%5d) ", j, m->vtable_index());
4439 m->access_flags().print_on(&log_stream);
4440 log_stream.print(" -- ");
4441 m->print_name(&log_stream);
4442 log_stream.cr();
4443 }
4444 log_trace(redefine, class, dump)("_matching_methods --");
4445 for (j = 0; j < _matching_methods_length; ++j) {
4446 LogStreamHandle(Trace, redefine, class, dump) log_stream;
4447 Method* m = _matching_old_methods[j];
4448 log_stream.print("%4d (%5d) ", j, m->vtable_index());
4449 m->access_flags().print_on(&log_stream);
4450 log_stream.print(" -- ");
4451 m->print_name();
4452 log_stream.cr();
4453
4454 m = _matching_new_methods[j];
4455 log_stream.print(" (%5d) ", m->vtable_index());
4456 m->access_flags().print_on(&log_stream);
4457 log_stream.cr();
4458 }
4459 log_trace(redefine, class, dump)("_deleted_methods --");
4460 for (j = 0; j < _deleted_methods_length; ++j) {
4461 LogStreamHandle(Trace, redefine, class, dump) log_stream;
4462 Method* m = _deleted_methods[j];
4463 log_stream.print("%4d (%5d) ", j, m->vtable_index());
4464 m->access_flags().print_on(&log_stream);
4465 log_stream.print(" -- ");
4466 m->print_name(&log_stream);
4467 log_stream.cr();
4468 }
4469 log_trace(redefine, class, dump)("_added_methods --");
4470 for (j = 0; j < _added_methods_length; ++j) {
4471 LogStreamHandle(Trace, redefine, class, dump) log_stream;
4472 Method* m = _added_methods[j];
4473 log_stream.print("%4d (%5d) ", j, m->vtable_index());
4474 m->access_flags().print_on(&log_stream);
4475 log_stream.print(" -- ");
4476 m->print_name(&log_stream);
4477 log_stream.cr();
4478 }
4479 }
4480
4481 void VM_RedefineClasses::print_on_error(outputStream* st) const {
4482 VM_Operation::print_on_error(st);
4483 if (_the_class != NULL) {
4484 ResourceMark rm;
4485 st->print_cr(", redefining class %s", _the_class->external_name());
4486 }
4487 }