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 jvmtiError check_permitted_subclasses_attribute(InstanceKlass* the_class,
858 InstanceKlass* scratch_class) {
859 // Check whether the class PermittedSubclasses attribute has been changed.
860 Thread* thread = Thread::current();
861 ResourceMark rm(thread);
862 Array<u2>* the_permitted_subclasses = the_class->permitted_subclasses();
863 Array<u2>* scr_permitted_subclasses = scratch_class->permitted_subclasses();
864 bool the_subclasses_exist = the_permitted_subclasses != Universe::the_empty_short_array();
865 bool scr_subclasses_exist = scr_permitted_subclasses != Universe::the_empty_short_array();
866 int subclasses_len = the_permitted_subclasses->length();
867 if (the_subclasses_exist && scr_subclasses_exist) {
868 if (subclasses_len != scr_permitted_subclasses->length()) {
869 log_trace(redefine, class, sealed)
870 ("redefined class %s attribute change error: PermittedSubclasses len=%d changed to len=%d",
871 the_class->external_name(), subclasses_len, scr_permitted_subclasses->length());
872 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_CLASS_ATTRIBUTE_CHANGED;
873 }
874
875 // The order of entries in the PermittedSubclasses array is not specified so
876 // we have to explicitly check for the same contents. We do this by copying
877 // the referenced symbols into their own arrays, sorting them and then
878 // comparing each element pair.
879
880 Symbol** the_syms = NEW_RESOURCE_ARRAY_RETURN_NULL(Symbol*, subclasses_len);
881 Symbol** scr_syms = NEW_RESOURCE_ARRAY_RETURN_NULL(Symbol*, subclasses_len);
882
883 if (the_syms == NULL || scr_syms == NULL) {
884 return JVMTI_ERROR_OUT_OF_MEMORY;
885 }
886
887 for (int i = 0; i < subclasses_len; i++) {
888 int the_cp_index = the_permitted_subclasses->at(i);
889 int scr_cp_index = scr_permitted_subclasses->at(i);
890 the_syms[i] = the_class->constants()->klass_name_at(the_cp_index);
891 scr_syms[i] = scratch_class->constants()->klass_name_at(scr_cp_index);
892 }
893
894 qsort(the_syms, subclasses_len, sizeof(Symbol*), symcmp);
895 qsort(scr_syms, subclasses_len, sizeof(Symbol*), symcmp);
896
897 for (int i = 0; i < subclasses_len; i++) {
898 if (the_syms[i] != scr_syms[i]) {
899 log_trace(redefine, class, sealed)
900 ("redefined class %s attribute change error: PermittedSubclasses[%d]: %s changed to %s",
901 the_class->external_name(), i, the_syms[i]->as_C_string(), scr_syms[i]->as_C_string());
902 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_CLASS_ATTRIBUTE_CHANGED;
903 }
904 }
905 } else if (the_subclasses_exist ^ scr_subclasses_exist) {
906 const char* action_str = (the_subclasses_exist) ? "removed" : "added";
907 log_trace(redefine, class, sealed)
908 ("redefined class %s attribute change error: PermittedSubclasses attribute %s",
909 the_class->external_name(), action_str);
910 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_CLASS_ATTRIBUTE_CHANGED;
911 }
912
913 return JVMTI_ERROR_NONE;
914 }
915
916 static bool can_add_or_delete(Method* m) {
917 // Compatibility mode
918 return (AllowRedefinitionToAddDeleteMethods &&
919 (m->is_private() && (m->is_static() || m->is_final())));
920 }
921
922 jvmtiError VM_RedefineClasses::compare_and_normalize_class_versions(
923 InstanceKlass* the_class,
924 InstanceKlass* scratch_class) {
925 int i;
926
927 // Check superclasses, or rather their names, since superclasses themselves can be
928 // requested to replace.
929 // Check for NULL superclass first since this might be java.lang.Object
930 if (the_class->super() != scratch_class->super() &&
931 (the_class->super() == NULL || scratch_class->super() == NULL ||
932 the_class->super()->name() !=
933 scratch_class->super()->name())) {
934 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_HIERARCHY_CHANGED;
935 }
936
937 // Check if the number, names and order of directly implemented interfaces are the same.
938 // I think in principle we should just check if the sets of names of directly implemented
939 // interfaces are the same, i.e. the order of declaration (which, however, if changed in the
940 // .java file, also changes in .class file) should not matter. However, comparing sets is
941 // technically a bit more difficult, and, more importantly, I am not sure at present that the
942 // order of interfaces does not matter on the implementation level, i.e. that the VM does not
943 // rely on it somewhere.
944 Array<InstanceKlass*>* k_interfaces = the_class->local_interfaces();
945 Array<InstanceKlass*>* k_new_interfaces = scratch_class->local_interfaces();
946 int n_intfs = k_interfaces->length();
947 if (n_intfs != k_new_interfaces->length()) {
948 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_HIERARCHY_CHANGED;
949 }
950 for (i = 0; i < n_intfs; i++) {
951 if (k_interfaces->at(i)->name() !=
952 k_new_interfaces->at(i)->name()) {
953 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_HIERARCHY_CHANGED;
954 }
955 }
956
957 // Check whether class is in the error init state.
958 if (the_class->is_in_error_state()) {
959 // TBD #5057930: special error code is needed in 1.6
960 return JVMTI_ERROR_INVALID_CLASS;
961 }
962
963 // Check whether the nest-related attributes have been changed.
964 jvmtiError err = check_nest_attributes(the_class, scratch_class);
965 if (err != JVMTI_ERROR_NONE) {
966 return err;
967 }
968
969 // Check whether the Record attribute has been changed.
970 err = check_record_attribute(the_class, scratch_class);
971 if (err != JVMTI_ERROR_NONE) {
972 return err;
973 }
974
975 // Check whether the PermittedSubclasses attribute has been changed.
976 err = check_permitted_subclasses_attribute(the_class, scratch_class);
977 if (err != JVMTI_ERROR_NONE) {
978 return err;
979 }
980
981 // Check whether class modifiers are the same.
982 jushort old_flags = (jushort) the_class->access_flags().get_flags();
983 jushort new_flags = (jushort) scratch_class->access_flags().get_flags();
984 if (old_flags != new_flags) {
985 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_CLASS_MODIFIERS_CHANGED;
986 }
987
988 // Check if the number, names, types and order of fields declared in these classes
989 // are the same.
990 JavaFieldStream old_fs(the_class);
991 JavaFieldStream new_fs(scratch_class);
992 for (; !old_fs.done() && !new_fs.done(); old_fs.next(), new_fs.next()) {
993 // access
994 old_flags = old_fs.access_flags().as_short();
995 new_flags = new_fs.access_flags().as_short();
996 if ((old_flags ^ new_flags) & JVM_RECOGNIZED_FIELD_MODIFIERS) {
997 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_SCHEMA_CHANGED;
998 }
999 // offset
1000 if (old_fs.offset() != new_fs.offset()) {
1001 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_SCHEMA_CHANGED;
1002 }
1003 // name and signature
1004 Symbol* name_sym1 = the_class->constants()->symbol_at(old_fs.name_index());
1005 Symbol* sig_sym1 = the_class->constants()->symbol_at(old_fs.signature_index());
1006 Symbol* name_sym2 = scratch_class->constants()->symbol_at(new_fs.name_index());
1007 Symbol* sig_sym2 = scratch_class->constants()->symbol_at(new_fs.signature_index());
1008 if (name_sym1 != name_sym2 || sig_sym1 != sig_sym2) {
1009 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_SCHEMA_CHANGED;
1010 }
1011 }
1012
1013 // If both streams aren't done then we have a differing number of
1014 // fields.
1015 if (!old_fs.done() || !new_fs.done()) {
1016 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_SCHEMA_CHANGED;
1017 }
1018
1019 // Do a parallel walk through the old and new methods. Detect
1020 // cases where they match (exist in both), have been added in
1021 // the new methods, or have been deleted (exist only in the
1022 // old methods). The class file parser places methods in order
1023 // by method name, but does not order overloaded methods by
1024 // signature. In order to determine what fate befell the methods,
1025 // this code places the overloaded new methods that have matching
1026 // old methods in the same order as the old methods and places
1027 // new overloaded methods at the end of overloaded methods of
1028 // that name. The code for this order normalization is adapted
1029 // from the algorithm used in InstanceKlass::find_method().
1030 // Since we are swapping out of order entries as we find them,
1031 // we only have to search forward through the overloaded methods.
1032 // Methods which are added and have the same name as an existing
1033 // method (but different signature) will be put at the end of
1034 // the methods with that name, and the name mismatch code will
1035 // handle them.
1036 Array<Method*>* k_old_methods(the_class->methods());
1037 Array<Method*>* k_new_methods(scratch_class->methods());
1038 int n_old_methods = k_old_methods->length();
1039 int n_new_methods = k_new_methods->length();
1040 Thread* thread = Thread::current();
1041
1042 int ni = 0;
1043 int oi = 0;
1044 while (true) {
1045 Method* k_old_method;
1046 Method* k_new_method;
1047 enum { matched, added, deleted, undetermined } method_was = undetermined;
1048
1049 if (oi >= n_old_methods) {
1050 if (ni >= n_new_methods) {
1051 break; // we've looked at everything, done
1052 }
1053 // New method at the end
1054 k_new_method = k_new_methods->at(ni);
1055 method_was = added;
1056 } else if (ni >= n_new_methods) {
1057 // Old method, at the end, is deleted
1058 k_old_method = k_old_methods->at(oi);
1059 method_was = deleted;
1060 } else {
1061 // There are more methods in both the old and new lists
1062 k_old_method = k_old_methods->at(oi);
1063 k_new_method = k_new_methods->at(ni);
1064 if (k_old_method->name() != k_new_method->name()) {
1065 // Methods are sorted by method name, so a mismatch means added
1066 // or deleted
1067 if (k_old_method->name()->fast_compare(k_new_method->name()) > 0) {
1068 method_was = added;
1069 } else {
1070 method_was = deleted;
1071 }
1072 } else if (k_old_method->signature() == k_new_method->signature()) {
1073 // Both the name and signature match
1074 method_was = matched;
1075 } else {
1076 // The name matches, but the signature doesn't, which means we have to
1077 // search forward through the new overloaded methods.
1078 int nj; // outside the loop for post-loop check
1079 for (nj = ni + 1; nj < n_new_methods; nj++) {
1080 Method* m = k_new_methods->at(nj);
1081 if (k_old_method->name() != m->name()) {
1082 // reached another method name so no more overloaded methods
1083 method_was = deleted;
1084 break;
1085 }
1086 if (k_old_method->signature() == m->signature()) {
1087 // found a match so swap the methods
1088 k_new_methods->at_put(ni, m);
1089 k_new_methods->at_put(nj, k_new_method);
1090 k_new_method = m;
1091 method_was = matched;
1092 break;
1093 }
1094 }
1095
1096 if (nj >= n_new_methods) {
1097 // reached the end without a match; so method was deleted
1098 method_was = deleted;
1099 }
1100 }
1101 }
1102
1103 switch (method_was) {
1104 case matched:
1105 // methods match, be sure modifiers do too
1106 old_flags = (jushort) k_old_method->access_flags().get_flags();
1107 new_flags = (jushort) k_new_method->access_flags().get_flags();
1108 if ((old_flags ^ new_flags) & ~(JVM_ACC_NATIVE)) {
1109 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_METHOD_MODIFIERS_CHANGED;
1110 }
1111 {
1112 u2 new_num = k_new_method->method_idnum();
1113 u2 old_num = k_old_method->method_idnum();
1114 if (new_num != old_num) {
1115 Method* idnum_owner = scratch_class->method_with_idnum(old_num);
1116 if (idnum_owner != NULL) {
1117 // There is already a method assigned this idnum -- switch them
1118 // Take current and original idnum from the new_method
1119 idnum_owner->set_method_idnum(new_num);
1120 idnum_owner->set_orig_method_idnum(k_new_method->orig_method_idnum());
1121 }
1122 // Take current and original idnum from the old_method
1123 k_new_method->set_method_idnum(old_num);
1124 k_new_method->set_orig_method_idnum(k_old_method->orig_method_idnum());
1125 if (thread->has_pending_exception()) {
1126 return JVMTI_ERROR_OUT_OF_MEMORY;
1127 }
1128 }
1129 }
1130 log_trace(redefine, class, normalize)
1131 ("Method matched: new: %s [%d] == old: %s [%d]",
1132 k_new_method->name_and_sig_as_C_string(), ni, k_old_method->name_and_sig_as_C_string(), oi);
1133 // advance to next pair of methods
1134 ++oi;
1135 ++ni;
1136 break;
1137 case added:
1138 // method added, see if it is OK
1139 if (!can_add_or_delete(k_new_method)) {
1140 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_METHOD_ADDED;
1141 }
1142 {
1143 u2 num = the_class->next_method_idnum();
1144 if (num == ConstMethod::UNSET_IDNUM) {
1145 // cannot add any more methods
1146 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_METHOD_ADDED;
1147 }
1148 u2 new_num = k_new_method->method_idnum();
1149 Method* idnum_owner = scratch_class->method_with_idnum(num);
1150 if (idnum_owner != NULL) {
1151 // There is already a method assigned this idnum -- switch them
1152 // Take current and original idnum from the new_method
1153 idnum_owner->set_method_idnum(new_num);
1154 idnum_owner->set_orig_method_idnum(k_new_method->orig_method_idnum());
1155 }
1156 k_new_method->set_method_idnum(num);
1157 k_new_method->set_orig_method_idnum(num);
1158 if (thread->has_pending_exception()) {
1159 return JVMTI_ERROR_OUT_OF_MEMORY;
1160 }
1161 }
1162 log_trace(redefine, class, normalize)
1163 ("Method added: new: %s [%d]", k_new_method->name_and_sig_as_C_string(), ni);
1164 ++ni; // advance to next new method
1165 break;
1166 case deleted:
1167 // method deleted, see if it is OK
1168 if (!can_add_or_delete(k_old_method)) {
1169 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_METHOD_DELETED;
1170 }
1171 log_trace(redefine, class, normalize)
1172 ("Method deleted: old: %s [%d]", k_old_method->name_and_sig_as_C_string(), oi);
1173 ++oi; // advance to next old method
1174 break;
1175 default:
1176 ShouldNotReachHere();
1177 }
1178 }
1179
1180 return JVMTI_ERROR_NONE;
1181 }
1182
1183
1184 // Find new constant pool index value for old constant pool index value
1185 // by seaching the index map. Returns zero (0) if there is no mapped
1186 // value for the old constant pool index.
1187 int VM_RedefineClasses::find_new_index(int old_index) {
1188 if (_index_map_count == 0) {
1189 // map is empty so nothing can be found
1190 return 0;
1191 }
1192
1193 if (old_index < 1 || old_index >= _index_map_p->length()) {
1194 // The old_index is out of range so it is not mapped. This should
1195 // not happen in regular constant pool merging use, but it can
1196 // happen if a corrupt annotation is processed.
1197 return 0;
1198 }
1199
1200 int value = _index_map_p->at(old_index);
1201 if (value == -1) {
1202 // the old_index is not mapped
1203 return 0;
1204 }
1205
1206 return value;
1207 } // end find_new_index()
1208
1209
1210 // Find new bootstrap specifier index value for old bootstrap specifier index
1211 // value by seaching the index map. Returns unused index (-1) if there is
1212 // no mapped value for the old bootstrap specifier index.
1213 int VM_RedefineClasses::find_new_operand_index(int old_index) {
1214 if (_operands_index_map_count == 0) {
1215 // map is empty so nothing can be found
1216 return -1;
1217 }
1218
1219 if (old_index == -1 || old_index >= _operands_index_map_p->length()) {
1220 // The old_index is out of range so it is not mapped.
1221 // This should not happen in regular constant pool merging use.
1222 return -1;
1223 }
1224
1225 int value = _operands_index_map_p->at(old_index);
1226 if (value == -1) {
1227 // the old_index is not mapped
1228 return -1;
1229 }
1230
1231 return value;
1232 } // end find_new_operand_index()
1233
1234
1235 // Returns true if the current mismatch is due to a resolved/unresolved
1236 // class pair. Otherwise, returns false.
1237 bool VM_RedefineClasses::is_unresolved_class_mismatch(const constantPoolHandle& cp1,
1238 int index1, const constantPoolHandle& cp2, int index2) {
1239
1240 jbyte t1 = cp1->tag_at(index1).value();
1241 if (t1 != JVM_CONSTANT_Class && t1 != JVM_CONSTANT_UnresolvedClass) {
1242 return false; // wrong entry type; not our special case
1243 }
1244
1245 jbyte t2 = cp2->tag_at(index2).value();
1246 if (t2 != JVM_CONSTANT_Class && t2 != JVM_CONSTANT_UnresolvedClass) {
1247 return false; // wrong entry type; not our special case
1248 }
1249
1250 if (t1 == t2) {
1251 return false; // not a mismatch; not our special case
1252 }
1253
1254 char *s1 = cp1->klass_name_at(index1)->as_C_string();
1255 char *s2 = cp2->klass_name_at(index2)->as_C_string();
1256 if (strcmp(s1, s2) != 0) {
1257 return false; // strings don't match; not our special case
1258 }
1259
1260 return true; // made it through the gauntlet; this is our special case
1261 } // end is_unresolved_class_mismatch()
1262
1263
1264 jvmtiError VM_RedefineClasses::load_new_class_versions(TRAPS) {
1265
1266 // For consistency allocate memory using os::malloc wrapper.
1267 _scratch_classes = (InstanceKlass**)
1268 os::malloc(sizeof(InstanceKlass*) * _class_count, mtClass);
1269 if (_scratch_classes == NULL) {
1270 return JVMTI_ERROR_OUT_OF_MEMORY;
1271 }
1272 // Zero initialize the _scratch_classes array.
1273 for (int i = 0; i < _class_count; i++) {
1274 _scratch_classes[i] = NULL;
1275 }
1276
1277 ResourceMark rm(THREAD);
1278
1279 JvmtiThreadState *state = JvmtiThreadState::state_for(JavaThread::current());
1280 // state can only be NULL if the current thread is exiting which
1281 // should not happen since we're trying to do a RedefineClasses
1282 guarantee(state != NULL, "exiting thread calling load_new_class_versions");
1283 for (int i = 0; i < _class_count; i++) {
1284 // Create HandleMark so that any handles created while loading new class
1285 // versions are deleted. Constant pools are deallocated while merging
1286 // constant pools
1287 HandleMark hm(THREAD);
1288 InstanceKlass* the_class = get_ik(_class_defs[i].klass);
1289 Symbol* the_class_sym = the_class->name();
1290
1291 log_debug(redefine, class, load)
1292 ("loading name=%s kind=%d (avail_mem=" UINT64_FORMAT "K)",
1293 the_class->external_name(), _class_load_kind, os::available_memory() >> 10);
1294
1295 ClassFileStream st((u1*)_class_defs[i].class_bytes,
1296 _class_defs[i].class_byte_count,
1297 "__VM_RedefineClasses__",
1298 ClassFileStream::verify);
1299
1300 // Parse the stream.
1301 Handle the_class_loader(THREAD, the_class->class_loader());
1302 Handle protection_domain(THREAD, the_class->protection_domain());
1303 // Set redefined class handle in JvmtiThreadState class.
1304 // This redefined class is sent to agent event handler for class file
1305 // load hook event.
1306 state->set_class_being_redefined(the_class, _class_load_kind);
1307
1308 ClassLoadInfo cl_info(protection_domain);
1309 InstanceKlass* scratch_class = SystemDictionary::parse_stream(
1310 the_class_sym,
1311 the_class_loader,
1312 &st,
1313 cl_info,
1314 THREAD);
1315 // Clear class_being_redefined just to be sure.
1316 state->clear_class_being_redefined();
1317
1318 // TODO: if this is retransform, and nothing changed we can skip it
1319
1320 // Need to clean up allocated InstanceKlass if there's an error so assign
1321 // the result here. Caller deallocates all the scratch classes in case of
1322 // an error.
1323 _scratch_classes[i] = scratch_class;
1324
1325 if (HAS_PENDING_EXCEPTION) {
1326 Symbol* ex_name = PENDING_EXCEPTION->klass()->name();
1327 log_info(redefine, class, load, exceptions)("parse_stream exception: '%s'", ex_name->as_C_string());
1328 CLEAR_PENDING_EXCEPTION;
1329
1330 if (ex_name == vmSymbols::java_lang_UnsupportedClassVersionError()) {
1331 return JVMTI_ERROR_UNSUPPORTED_VERSION;
1332 } else if (ex_name == vmSymbols::java_lang_ClassFormatError()) {
1333 return JVMTI_ERROR_INVALID_CLASS_FORMAT;
1334 } else if (ex_name == vmSymbols::java_lang_ClassCircularityError()) {
1335 return JVMTI_ERROR_CIRCULAR_CLASS_DEFINITION;
1336 } else if (ex_name == vmSymbols::java_lang_NoClassDefFoundError()) {
1337 // The message will be "XXX (wrong name: YYY)"
1338 return JVMTI_ERROR_NAMES_DONT_MATCH;
1339 } else if (ex_name == vmSymbols::java_lang_OutOfMemoryError()) {
1340 return JVMTI_ERROR_OUT_OF_MEMORY;
1341 } else { // Just in case more exceptions can be thrown..
1342 return JVMTI_ERROR_FAILS_VERIFICATION;
1343 }
1344 }
1345
1346 // Ensure class is linked before redefine
1347 if (!the_class->is_linked()) {
1348 the_class->link_class(THREAD);
1349 if (HAS_PENDING_EXCEPTION) {
1350 Symbol* ex_name = PENDING_EXCEPTION->klass()->name();
1351 log_info(redefine, class, load, exceptions)("link_class exception: '%s'", ex_name->as_C_string());
1352 CLEAR_PENDING_EXCEPTION;
1353 if (ex_name == vmSymbols::java_lang_OutOfMemoryError()) {
1354 return JVMTI_ERROR_OUT_OF_MEMORY;
1355 } else {
1356 return JVMTI_ERROR_INTERNAL;
1357 }
1358 }
1359 }
1360
1361 // Do the validity checks in compare_and_normalize_class_versions()
1362 // before verifying the byte codes. By doing these checks first, we
1363 // limit the number of functions that require redirection from
1364 // the_class to scratch_class. In particular, we don't have to
1365 // modify JNI GetSuperclass() and thus won't change its performance.
1366 jvmtiError res = compare_and_normalize_class_versions(the_class,
1367 scratch_class);
1368 if (res != JVMTI_ERROR_NONE) {
1369 return res;
1370 }
1371
1372 // verify what the caller passed us
1373 {
1374 // The bug 6214132 caused the verification to fail.
1375 // Information about the_class and scratch_class is temporarily
1376 // recorded into jvmtiThreadState. This data is used to redirect
1377 // the_class to scratch_class in the JVM_* functions called by the
1378 // verifier. Please, refer to jvmtiThreadState.hpp for the detailed
1379 // description.
1380 RedefineVerifyMark rvm(the_class, scratch_class, state);
1381 Verifier::verify(scratch_class, true, THREAD);
1382 }
1383
1384 if (HAS_PENDING_EXCEPTION) {
1385 Symbol* ex_name = PENDING_EXCEPTION->klass()->name();
1386 log_info(redefine, class, load, exceptions)("verify_byte_codes exception: '%s'", ex_name->as_C_string());
1387 CLEAR_PENDING_EXCEPTION;
1388 if (ex_name == vmSymbols::java_lang_OutOfMemoryError()) {
1389 return JVMTI_ERROR_OUT_OF_MEMORY;
1390 } else {
1391 // tell the caller the bytecodes are bad
1392 return JVMTI_ERROR_FAILS_VERIFICATION;
1393 }
1394 }
1395
1396 res = merge_cp_and_rewrite(the_class, scratch_class, THREAD);
1397 if (HAS_PENDING_EXCEPTION) {
1398 Symbol* ex_name = PENDING_EXCEPTION->klass()->name();
1399 log_info(redefine, class, load, exceptions)("merge_cp_and_rewrite exception: '%s'", ex_name->as_C_string());
1400 CLEAR_PENDING_EXCEPTION;
1401 if (ex_name == vmSymbols::java_lang_OutOfMemoryError()) {
1402 return JVMTI_ERROR_OUT_OF_MEMORY;
1403 } else {
1404 return JVMTI_ERROR_INTERNAL;
1405 }
1406 }
1407
1408 if (VerifyMergedCPBytecodes) {
1409 // verify what we have done during constant pool merging
1410 {
1411 RedefineVerifyMark rvm(the_class, scratch_class, state);
1412 Verifier::verify(scratch_class, true, THREAD);
1413 }
1414
1415 if (HAS_PENDING_EXCEPTION) {
1416 Symbol* ex_name = PENDING_EXCEPTION->klass()->name();
1417 log_info(redefine, class, load, exceptions)
1418 ("verify_byte_codes post merge-CP exception: '%s'", ex_name->as_C_string());
1419 CLEAR_PENDING_EXCEPTION;
1420 if (ex_name == vmSymbols::java_lang_OutOfMemoryError()) {
1421 return JVMTI_ERROR_OUT_OF_MEMORY;
1422 } else {
1423 // tell the caller that constant pool merging screwed up
1424 return JVMTI_ERROR_INTERNAL;
1425 }
1426 }
1427 }
1428
1429 Rewriter::rewrite(scratch_class, THREAD);
1430 if (!HAS_PENDING_EXCEPTION) {
1431 scratch_class->link_methods(THREAD);
1432 }
1433 if (HAS_PENDING_EXCEPTION) {
1434 Symbol* ex_name = PENDING_EXCEPTION->klass()->name();
1435 log_info(redefine, class, load, exceptions)
1436 ("Rewriter::rewrite or link_methods exception: '%s'", ex_name->as_C_string());
1437 CLEAR_PENDING_EXCEPTION;
1438 if (ex_name == vmSymbols::java_lang_OutOfMemoryError()) {
1439 return JVMTI_ERROR_OUT_OF_MEMORY;
1440 } else {
1441 return JVMTI_ERROR_INTERNAL;
1442 }
1443 }
1444
1445 log_debug(redefine, class, load)
1446 ("loaded name=%s (avail_mem=" UINT64_FORMAT "K)", the_class->external_name(), os::available_memory() >> 10);
1447 }
1448
1449 return JVMTI_ERROR_NONE;
1450 }
1451
1452
1453 // Map old_index to new_index as needed. scratch_cp is only needed
1454 // for log calls.
1455 void VM_RedefineClasses::map_index(const constantPoolHandle& scratch_cp,
1456 int old_index, int new_index) {
1457 if (find_new_index(old_index) != 0) {
1458 // old_index is already mapped
1459 return;
1460 }
1461
1462 if (old_index == new_index) {
1463 // no mapping is needed
1464 return;
1465 }
1466
1467 _index_map_p->at_put(old_index, new_index);
1468 _index_map_count++;
1469
1470 log_trace(redefine, class, constantpool)
1471 ("mapped tag %d at index %d to %d", scratch_cp->tag_at(old_index).value(), old_index, new_index);
1472 } // end map_index()
1473
1474
1475 // Map old_index to new_index as needed.
1476 void VM_RedefineClasses::map_operand_index(int old_index, int new_index) {
1477 if (find_new_operand_index(old_index) != -1) {
1478 // old_index is already mapped
1479 return;
1480 }
1481
1482 if (old_index == new_index) {
1483 // no mapping is needed
1484 return;
1485 }
1486
1487 _operands_index_map_p->at_put(old_index, new_index);
1488 _operands_index_map_count++;
1489
1490 log_trace(redefine, class, constantpool)("mapped bootstrap specifier at index %d to %d", old_index, new_index);
1491 } // end map_index()
1492
1493
1494 // Merge old_cp and scratch_cp and return the results of the merge via
1495 // merge_cp_p. The number of entries in *merge_cp_p is returned via
1496 // merge_cp_length_p. The entries in old_cp occupy the same locations
1497 // in *merge_cp_p. Also creates a map of indices from entries in
1498 // scratch_cp to the corresponding entry in *merge_cp_p. Index map
1499 // entries are only created for entries in scratch_cp that occupy a
1500 // different location in *merged_cp_p.
1501 bool VM_RedefineClasses::merge_constant_pools(const constantPoolHandle& old_cp,
1502 const constantPoolHandle& scratch_cp, constantPoolHandle *merge_cp_p,
1503 int *merge_cp_length_p, TRAPS) {
1504
1505 if (merge_cp_p == NULL) {
1506 assert(false, "caller must provide scratch constantPool");
1507 return false; // robustness
1508 }
1509 if (merge_cp_length_p == NULL) {
1510 assert(false, "caller must provide scratch CP length");
1511 return false; // robustness
1512 }
1513 // Worst case we need old_cp->length() + scratch_cp()->length(),
1514 // but the caller might be smart so make sure we have at least
1515 // the minimum.
1516 if ((*merge_cp_p)->length() < old_cp->length()) {
1517 assert(false, "merge area too small");
1518 return false; // robustness
1519 }
1520
1521 log_info(redefine, class, constantpool)("old_cp_len=%d, scratch_cp_len=%d", old_cp->length(), scratch_cp->length());
1522
1523 {
1524 // Pass 0:
1525 // The old_cp is copied to *merge_cp_p; this means that any code
1526 // using old_cp does not have to change. This work looks like a
1527 // perfect fit for ConstantPool*::copy_cp_to(), but we need to
1528 // handle one special case:
1529 // - revert JVM_CONSTANT_Class to JVM_CONSTANT_UnresolvedClass
1530 // This will make verification happy.
1531
1532 int old_i; // index into old_cp
1533
1534 // index zero (0) is not used in constantPools
1535 for (old_i = 1; old_i < old_cp->length(); old_i++) {
1536 // leave debugging crumb
1537 jbyte old_tag = old_cp->tag_at(old_i).value();
1538 switch (old_tag) {
1539 case JVM_CONSTANT_Class:
1540 case JVM_CONSTANT_UnresolvedClass:
1541 // revert the copy to JVM_CONSTANT_UnresolvedClass
1542 // May be resolving while calling this so do the same for
1543 // JVM_CONSTANT_UnresolvedClass (klass_name_at() deals with transition)
1544 (*merge_cp_p)->temp_unresolved_klass_at_put(old_i,
1545 old_cp->klass_name_index_at(old_i));
1546 break;
1547
1548 case JVM_CONSTANT_Double:
1549 case JVM_CONSTANT_Long:
1550 // just copy the entry to *merge_cp_p, but double and long take
1551 // two constant pool entries
1552 ConstantPool::copy_entry_to(old_cp, old_i, *merge_cp_p, old_i, CHECK_false);
1553 old_i++;
1554 break;
1555
1556 default:
1557 // just copy the entry to *merge_cp_p
1558 ConstantPool::copy_entry_to(old_cp, old_i, *merge_cp_p, old_i, CHECK_false);
1559 break;
1560 }
1561 } // end for each old_cp entry
1562
1563 ConstantPool::copy_operands(old_cp, *merge_cp_p, CHECK_false);
1564 (*merge_cp_p)->extend_operands(scratch_cp, CHECK_false);
1565
1566 // We don't need to sanity check that *merge_cp_length_p is within
1567 // *merge_cp_p bounds since we have the minimum on-entry check above.
1568 (*merge_cp_length_p) = old_i;
1569 }
1570
1571 // merge_cp_len should be the same as old_cp->length() at this point
1572 // so this trace message is really a "warm-and-breathing" message.
1573 log_debug(redefine, class, constantpool)("after pass 0: merge_cp_len=%d", *merge_cp_length_p);
1574
1575 int scratch_i; // index into scratch_cp
1576 {
1577 // Pass 1a:
1578 // Compare scratch_cp entries to the old_cp entries that we have
1579 // already copied to *merge_cp_p. In this pass, we are eliminating
1580 // exact duplicates (matching entry at same index) so we only
1581 // compare entries in the common indice range.
1582 int increment = 1;
1583 int pass1a_length = MIN2(old_cp->length(), scratch_cp->length());
1584 for (scratch_i = 1; scratch_i < pass1a_length; scratch_i += increment) {
1585 switch (scratch_cp->tag_at(scratch_i).value()) {
1586 case JVM_CONSTANT_Double:
1587 case JVM_CONSTANT_Long:
1588 // double and long take two constant pool entries
1589 increment = 2;
1590 break;
1591
1592 default:
1593 increment = 1;
1594 break;
1595 }
1596
1597 bool match = scratch_cp->compare_entry_to(scratch_i, *merge_cp_p,
1598 scratch_i, CHECK_false);
1599 if (match) {
1600 // found a match at the same index so nothing more to do
1601 continue;
1602 } else if (is_unresolved_class_mismatch(scratch_cp, scratch_i,
1603 *merge_cp_p, scratch_i)) {
1604 // The mismatch in compare_entry_to() above is because of a
1605 // resolved versus unresolved class entry at the same index
1606 // with the same string value. Since Pass 0 reverted any
1607 // class entries to unresolved class entries in *merge_cp_p,
1608 // we go with the unresolved class entry.
1609 continue;
1610 }
1611
1612 int found_i = scratch_cp->find_matching_entry(scratch_i, *merge_cp_p,
1613 CHECK_false);
1614 if (found_i != 0) {
1615 guarantee(found_i != scratch_i,
1616 "compare_entry_to() and find_matching_entry() do not agree");
1617
1618 // Found a matching entry somewhere else in *merge_cp_p so
1619 // just need a mapping entry.
1620 map_index(scratch_cp, scratch_i, found_i);
1621 continue;
1622 }
1623
1624 // The find_matching_entry() call above could fail to find a match
1625 // due to a resolved versus unresolved class or string entry situation
1626 // like we solved above with the is_unresolved_*_mismatch() calls.
1627 // However, we would have to call is_unresolved_*_mismatch() over
1628 // all of *merge_cp_p (potentially) and that doesn't seem to be
1629 // worth the time.
1630
1631 // No match found so we have to append this entry and any unique
1632 // referenced entries to *merge_cp_p.
1633 append_entry(scratch_cp, scratch_i, merge_cp_p, merge_cp_length_p,
1634 CHECK_false);
1635 }
1636 }
1637
1638 log_debug(redefine, class, constantpool)
1639 ("after pass 1a: merge_cp_len=%d, scratch_i=%d, index_map_len=%d",
1640 *merge_cp_length_p, scratch_i, _index_map_count);
1641
1642 if (scratch_i < scratch_cp->length()) {
1643 // Pass 1b:
1644 // old_cp is smaller than scratch_cp so there are entries in
1645 // scratch_cp that we have not yet processed. We take care of
1646 // those now.
1647 int increment = 1;
1648 for (; scratch_i < scratch_cp->length(); scratch_i += increment) {
1649 switch (scratch_cp->tag_at(scratch_i).value()) {
1650 case JVM_CONSTANT_Double:
1651 case JVM_CONSTANT_Long:
1652 // double and long take two constant pool entries
1653 increment = 2;
1654 break;
1655
1656 default:
1657 increment = 1;
1658 break;
1659 }
1660
1661 int found_i =
1662 scratch_cp->find_matching_entry(scratch_i, *merge_cp_p, CHECK_false);
1663 if (found_i != 0) {
1664 // Found a matching entry somewhere else in *merge_cp_p so
1665 // just need a mapping entry.
1666 map_index(scratch_cp, scratch_i, found_i);
1667 continue;
1668 }
1669
1670 // No match found so we have to append this entry and any unique
1671 // referenced entries to *merge_cp_p.
1672 append_entry(scratch_cp, scratch_i, merge_cp_p, merge_cp_length_p,
1673 CHECK_false);
1674 }
1675
1676 log_debug(redefine, class, constantpool)
1677 ("after pass 1b: merge_cp_len=%d, scratch_i=%d, index_map_len=%d",
1678 *merge_cp_length_p, scratch_i, _index_map_count);
1679 }
1680 finalize_operands_merge(*merge_cp_p, THREAD);
1681
1682 return true;
1683 } // end merge_constant_pools()
1684
1685
1686 // Scoped object to clean up the constant pool(s) created for merging
1687 class MergeCPCleaner {
1688 ClassLoaderData* _loader_data;
1689 ConstantPool* _cp;
1690 ConstantPool* _scratch_cp;
1691 public:
1692 MergeCPCleaner(ClassLoaderData* loader_data, ConstantPool* merge_cp) :
1693 _loader_data(loader_data), _cp(merge_cp), _scratch_cp(NULL) {}
1694 ~MergeCPCleaner() {
1695 _loader_data->add_to_deallocate_list(_cp);
1696 if (_scratch_cp != NULL) {
1697 _loader_data->add_to_deallocate_list(_scratch_cp);
1698 }
1699 }
1700 void add_scratch_cp(ConstantPool* scratch_cp) { _scratch_cp = scratch_cp; }
1701 };
1702
1703 // Merge constant pools between the_class and scratch_class and
1704 // potentially rewrite bytecodes in scratch_class to use the merged
1705 // constant pool.
1706 jvmtiError VM_RedefineClasses::merge_cp_and_rewrite(
1707 InstanceKlass* the_class, InstanceKlass* scratch_class,
1708 TRAPS) {
1709 // worst case merged constant pool length is old and new combined
1710 int merge_cp_length = the_class->constants()->length()
1711 + scratch_class->constants()->length();
1712
1713 // Constant pools are not easily reused so we allocate a new one
1714 // each time.
1715 // merge_cp is created unsafe for concurrent GC processing. It
1716 // should be marked safe before discarding it. Even though
1717 // garbage, if it crosses a card boundary, it may be scanned
1718 // in order to find the start of the first complete object on the card.
1719 ClassLoaderData* loader_data = the_class->class_loader_data();
1720 ConstantPool* merge_cp_oop =
1721 ConstantPool::allocate(loader_data,
1722 merge_cp_length,
1723 CHECK_(JVMTI_ERROR_OUT_OF_MEMORY));
1724 MergeCPCleaner cp_cleaner(loader_data, merge_cp_oop);
1725
1726 HandleMark hm(THREAD); // make sure handles are cleared before
1727 // MergeCPCleaner clears out merge_cp_oop
1728 constantPoolHandle merge_cp(THREAD, merge_cp_oop);
1729
1730 // Get constants() from the old class because it could have been rewritten
1731 // while we were at a safepoint allocating a new constant pool.
1732 constantPoolHandle old_cp(THREAD, the_class->constants());
1733 constantPoolHandle scratch_cp(THREAD, scratch_class->constants());
1734
1735 // If the length changed, the class was redefined out from under us. Return
1736 // an error.
1737 if (merge_cp_length != the_class->constants()->length()
1738 + scratch_class->constants()->length()) {
1739 return JVMTI_ERROR_INTERNAL;
1740 }
1741
1742 // Update the version number of the constant pools (may keep scratch_cp)
1743 merge_cp->increment_and_save_version(old_cp->version());
1744 scratch_cp->increment_and_save_version(old_cp->version());
1745
1746 ResourceMark rm(THREAD);
1747 _index_map_count = 0;
1748 _index_map_p = new intArray(scratch_cp->length(), scratch_cp->length(), -1);
1749
1750 _operands_cur_length = ConstantPool::operand_array_length(old_cp->operands());
1751 _operands_index_map_count = 0;
1752 int operands_index_map_len = ConstantPool::operand_array_length(scratch_cp->operands());
1753 _operands_index_map_p = new intArray(operands_index_map_len, operands_index_map_len, -1);
1754
1755 // reference to the cp holder is needed for copy_operands()
1756 merge_cp->set_pool_holder(scratch_class);
1757 bool result = merge_constant_pools(old_cp, scratch_cp, &merge_cp,
1758 &merge_cp_length, THREAD);
1759 merge_cp->set_pool_holder(NULL);
1760
1761 if (!result) {
1762 // The merge can fail due to memory allocation failure or due
1763 // to robustness checks.
1764 return JVMTI_ERROR_INTERNAL;
1765 }
1766
1767 // Save fields from the old_cp.
1768 merge_cp->copy_fields(old_cp());
1769 scratch_cp->copy_fields(old_cp());
1770
1771 log_info(redefine, class, constantpool)("merge_cp_len=%d, index_map_len=%d", merge_cp_length, _index_map_count);
1772
1773 if (_index_map_count == 0) {
1774 // there is nothing to map between the new and merged constant pools
1775
1776 if (old_cp->length() == scratch_cp->length()) {
1777 // The old and new constant pools are the same length and the
1778 // index map is empty. This means that the three constant pools
1779 // are equivalent (but not the same). Unfortunately, the new
1780 // constant pool has not gone through link resolution nor have
1781 // the new class bytecodes gone through constant pool cache
1782 // rewriting so we can't use the old constant pool with the new
1783 // class.
1784
1785 // toss the merged constant pool at return
1786 } else if (old_cp->length() < scratch_cp->length()) {
1787 // The old constant pool has fewer entries than the new constant
1788 // pool and the index map is empty. This means the new constant
1789 // pool is a superset of the old constant pool. However, the old
1790 // class bytecodes have already gone through constant pool cache
1791 // rewriting so we can't use the new constant pool with the old
1792 // class.
1793
1794 // toss the merged constant pool at return
1795 } else {
1796 // The old constant pool has more entries than the new constant
1797 // pool and the index map is empty. This means that both the old
1798 // and merged constant pools are supersets of the new constant
1799 // pool.
1800
1801 // Replace the new constant pool with a shrunken copy of the
1802 // merged constant pool
1803 set_new_constant_pool(loader_data, scratch_class, merge_cp, merge_cp_length,
1804 CHECK_(JVMTI_ERROR_OUT_OF_MEMORY));
1805 // The new constant pool replaces scratch_cp so have cleaner clean it up.
1806 // It can't be cleaned up while there are handles to it.
1807 cp_cleaner.add_scratch_cp(scratch_cp());
1808 }
1809 } else {
1810 if (log_is_enabled(Trace, redefine, class, constantpool)) {
1811 // don't want to loop unless we are tracing
1812 int count = 0;
1813 for (int i = 1; i < _index_map_p->length(); i++) {
1814 int value = _index_map_p->at(i);
1815
1816 if (value != -1) {
1817 log_trace(redefine, class, constantpool)("index_map[%d]: old=%d new=%d", count, i, value);
1818 count++;
1819 }
1820 }
1821 }
1822
1823 // We have entries mapped between the new and merged constant pools
1824 // so we have to rewrite some constant pool references.
1825 if (!rewrite_cp_refs(scratch_class, THREAD)) {
1826 return JVMTI_ERROR_INTERNAL;
1827 }
1828
1829 // Replace the new constant pool with a shrunken copy of the
1830 // merged constant pool so now the rewritten bytecodes have
1831 // valid references; the previous new constant pool will get
1832 // GCed.
1833 set_new_constant_pool(loader_data, scratch_class, merge_cp, merge_cp_length,
1834 CHECK_(JVMTI_ERROR_OUT_OF_MEMORY));
1835 // The new constant pool replaces scratch_cp so have cleaner clean it up.
1836 // It can't be cleaned up while there are handles to it.
1837 cp_cleaner.add_scratch_cp(scratch_cp());
1838 }
1839
1840 return JVMTI_ERROR_NONE;
1841 } // end merge_cp_and_rewrite()
1842
1843
1844 // Rewrite constant pool references in klass scratch_class.
1845 bool VM_RedefineClasses::rewrite_cp_refs(InstanceKlass* scratch_class,
1846 TRAPS) {
1847
1848 // rewrite constant pool references in the nest attributes:
1849 if (!rewrite_cp_refs_in_nest_attributes(scratch_class)) {
1850 // propagate failure back to caller
1851 return false;
1852 }
1853
1854 // rewrite constant pool references in the Record attribute:
1855 if (!rewrite_cp_refs_in_record_attribute(scratch_class, THREAD)) {
1856 // propagate failure back to caller
1857 return false;
1858 }
1859
1860 // rewrite constant pool references in the PermittedSubclasses attribute:
1861 if (!rewrite_cp_refs_in_permitted_subclasses_attribute(scratch_class)) {
1862 // propagate failure back to caller
1863 return false;
1864 }
1865
1866 // rewrite constant pool references in the methods:
1867 if (!rewrite_cp_refs_in_methods(scratch_class, THREAD)) {
1868 // propagate failure back to caller
1869 return false;
1870 }
1871
1872 // rewrite constant pool references in the class_annotations:
1873 if (!rewrite_cp_refs_in_class_annotations(scratch_class, THREAD)) {
1874 // propagate failure back to caller
1875 return false;
1876 }
1877
1878 // rewrite constant pool references in the fields_annotations:
1879 if (!rewrite_cp_refs_in_fields_annotations(scratch_class, THREAD)) {
1880 // propagate failure back to caller
1881 return false;
1882 }
1883
1884 // rewrite constant pool references in the methods_annotations:
1885 if (!rewrite_cp_refs_in_methods_annotations(scratch_class, THREAD)) {
1886 // propagate failure back to caller
1887 return false;
1888 }
1889
1890 // rewrite constant pool references in the methods_parameter_annotations:
1891 if (!rewrite_cp_refs_in_methods_parameter_annotations(scratch_class,
1892 THREAD)) {
1893 // propagate failure back to caller
1894 return false;
1895 }
1896
1897 // rewrite constant pool references in the methods_default_annotations:
1898 if (!rewrite_cp_refs_in_methods_default_annotations(scratch_class,
1899 THREAD)) {
1900 // propagate failure back to caller
1901 return false;
1902 }
1903
1904 // rewrite constant pool references in the class_type_annotations:
1905 if (!rewrite_cp_refs_in_class_type_annotations(scratch_class, THREAD)) {
1906 // propagate failure back to caller
1907 return false;
1908 }
1909
1910 // rewrite constant pool references in the fields_type_annotations:
1911 if (!rewrite_cp_refs_in_fields_type_annotations(scratch_class, THREAD)) {
1912 // propagate failure back to caller
1913 return false;
1914 }
1915
1916 // rewrite constant pool references in the methods_type_annotations:
1917 if (!rewrite_cp_refs_in_methods_type_annotations(scratch_class, THREAD)) {
1918 // propagate failure back to caller
1919 return false;
1920 }
1921
1922 // There can be type annotations in the Code part of a method_info attribute.
1923 // These annotations are not accessible, even by reflection.
1924 // Currently they are not even parsed by the ClassFileParser.
1925 // If runtime access is added they will also need to be rewritten.
1926
1927 // rewrite source file name index:
1928 u2 source_file_name_idx = scratch_class->source_file_name_index();
1929 if (source_file_name_idx != 0) {
1930 u2 new_source_file_name_idx = find_new_index(source_file_name_idx);
1931 if (new_source_file_name_idx != 0) {
1932 scratch_class->set_source_file_name_index(new_source_file_name_idx);
1933 }
1934 }
1935
1936 // rewrite class generic signature index:
1937 u2 generic_signature_index = scratch_class->generic_signature_index();
1938 if (generic_signature_index != 0) {
1939 u2 new_generic_signature_index = find_new_index(generic_signature_index);
1940 if (new_generic_signature_index != 0) {
1941 scratch_class->set_generic_signature_index(new_generic_signature_index);
1942 }
1943 }
1944
1945 return true;
1946 } // end rewrite_cp_refs()
1947
1948 // Rewrite constant pool references in the NestHost and NestMembers attributes.
1949 bool VM_RedefineClasses::rewrite_cp_refs_in_nest_attributes(
1950 InstanceKlass* scratch_class) {
1951
1952 u2 cp_index = scratch_class->nest_host_index();
1953 if (cp_index != 0) {
1954 scratch_class->set_nest_host_index(find_new_index(cp_index));
1955 }
1956 Array<u2>* nest_members = scratch_class->nest_members();
1957 for (int i = 0; i < nest_members->length(); i++) {
1958 u2 cp_index = nest_members->at(i);
1959 nest_members->at_put(i, find_new_index(cp_index));
1960 }
1961 return true;
1962 }
1963
1964 // Rewrite constant pool references in the Record attribute.
1965 bool VM_RedefineClasses::rewrite_cp_refs_in_record_attribute(
1966 InstanceKlass* scratch_class, TRAPS) {
1967 Array<RecordComponent*>* components = scratch_class->record_components();
1968 if (components != NULL) {
1969 for (int i = 0; i < components->length(); i++) {
1970 RecordComponent* component = components->at(i);
1971 u2 cp_index = component->name_index();
1972 component->set_name_index(find_new_index(cp_index));
1973 cp_index = component->descriptor_index();
1974 component->set_descriptor_index(find_new_index(cp_index));
1975 cp_index = component->generic_signature_index();
1976 if (cp_index != 0) {
1977 component->set_generic_signature_index(find_new_index(cp_index));
1978 }
1979
1980 AnnotationArray* annotations = component->annotations();
1981 if (annotations != NULL && annotations->length() != 0) {
1982 int byte_i = 0; // byte index into annotations
1983 if (!rewrite_cp_refs_in_annotations_typeArray(annotations, byte_i, THREAD)) {
1984 log_debug(redefine, class, annotation)("bad record_component_annotations at %d", i);
1985 // propagate failure back to caller
1986 return false;
1987 }
1988 }
1989
1990 AnnotationArray* type_annotations = component->type_annotations();
1991 if (type_annotations != NULL && type_annotations->length() != 0) {
1992 int byte_i = 0; // byte index into annotations
1993 if (!rewrite_cp_refs_in_annotations_typeArray(type_annotations, byte_i, THREAD)) {
1994 log_debug(redefine, class, annotation)("bad record_component_type_annotations at %d", i);
1995 // propagate failure back to caller
1996 return false;
1997 }
1998 }
1999 }
2000 }
2001 return true;
2002 }
2003
2004 // Rewrite constant pool references in the PermittedSubclasses attribute.
2005 bool VM_RedefineClasses::rewrite_cp_refs_in_permitted_subclasses_attribute(
2006 InstanceKlass* scratch_class) {
2007
2008 Array<u2>* permitted_subclasses = scratch_class->permitted_subclasses();
2009 assert(permitted_subclasses != NULL, "unexpected null permitted_subclasses");
2010 for (int i = 0; i < permitted_subclasses->length(); i++) {
2011 u2 cp_index = permitted_subclasses->at(i);
2012 permitted_subclasses->at_put(i, find_new_index(cp_index));
2013 }
2014 return true;
2015 }
2016
2017 // Rewrite constant pool references in the methods.
2018 bool VM_RedefineClasses::rewrite_cp_refs_in_methods(
2019 InstanceKlass* scratch_class, TRAPS) {
2020
2021 Array<Method*>* methods = scratch_class->methods();
2022
2023 if (methods == NULL || methods->length() == 0) {
2024 // no methods so nothing to do
2025 return true;
2026 }
2027
2028 // rewrite constant pool references in the methods:
2029 for (int i = methods->length() - 1; i >= 0; i--) {
2030 methodHandle method(THREAD, methods->at(i));
2031 methodHandle new_method;
2032 rewrite_cp_refs_in_method(method, &new_method, THREAD);
2033 if (!new_method.is_null()) {
2034 // the method has been replaced so save the new method version
2035 // even in the case of an exception. original method is on the
2036 // deallocation list.
2037 methods->at_put(i, new_method());
2038 }
2039 if (HAS_PENDING_EXCEPTION) {
2040 Symbol* ex_name = PENDING_EXCEPTION->klass()->name();
2041 log_info(redefine, class, load, exceptions)("rewrite_cp_refs_in_method exception: '%s'", ex_name->as_C_string());
2042 // Need to clear pending exception here as the super caller sets
2043 // the JVMTI_ERROR_INTERNAL if the returned value is false.
2044 CLEAR_PENDING_EXCEPTION;
2045 return false;
2046 }
2047 }
2048
2049 return true;
2050 }
2051
2052
2053 // Rewrite constant pool references in the specific method. This code
2054 // was adapted from Rewriter::rewrite_method().
2055 void VM_RedefineClasses::rewrite_cp_refs_in_method(methodHandle method,
2056 methodHandle *new_method_p, TRAPS) {
2057
2058 *new_method_p = methodHandle(); // default is no new method
2059
2060 // We cache a pointer to the bytecodes here in code_base. If GC
2061 // moves the Method*, then the bytecodes will also move which
2062 // will likely cause a crash. We create a NoSafepointVerifier
2063 // object to detect whether we pass a possible safepoint in this
2064 // code block.
2065 NoSafepointVerifier nsv;
2066
2067 // Bytecodes and their length
2068 address code_base = method->code_base();
2069 int code_length = method->code_size();
2070
2071 int bc_length;
2072 for (int bci = 0; bci < code_length; bci += bc_length) {
2073 address bcp = code_base + bci;
2074 Bytecodes::Code c = (Bytecodes::Code)(*bcp);
2075
2076 bc_length = Bytecodes::length_for(c);
2077 if (bc_length == 0) {
2078 // More complicated bytecodes report a length of zero so
2079 // we have to try again a slightly different way.
2080 bc_length = Bytecodes::length_at(method(), bcp);
2081 }
2082
2083 assert(bc_length != 0, "impossible bytecode length");
2084
2085 switch (c) {
2086 case Bytecodes::_ldc:
2087 {
2088 int cp_index = *(bcp + 1);
2089 int new_index = find_new_index(cp_index);
2090
2091 if (StressLdcRewrite && new_index == 0) {
2092 // If we are stressing ldc -> ldc_w rewriting, then we
2093 // always need a new_index value.
2094 new_index = cp_index;
2095 }
2096 if (new_index != 0) {
2097 // the original index is mapped so we have more work to do
2098 if (!StressLdcRewrite && new_index <= max_jubyte) {
2099 // The new value can still use ldc instead of ldc_w
2100 // unless we are trying to stress ldc -> ldc_w rewriting
2101 log_trace(redefine, class, constantpool)
2102 ("%s@" INTPTR_FORMAT " old=%d, new=%d", Bytecodes::name(c), p2i(bcp), cp_index, new_index);
2103 *(bcp + 1) = new_index;
2104 } else {
2105 log_trace(redefine, class, constantpool)
2106 ("%s->ldc_w@" INTPTR_FORMAT " old=%d, new=%d", Bytecodes::name(c), p2i(bcp), cp_index, new_index);
2107 // the new value needs ldc_w instead of ldc
2108 u_char inst_buffer[4]; // max instruction size is 4 bytes
2109 bcp = (address)inst_buffer;
2110 // construct new instruction sequence
2111 *bcp = Bytecodes::_ldc_w;
2112 bcp++;
2113 // Rewriter::rewrite_method() does not rewrite ldc -> ldc_w.
2114 // See comment below for difference between put_Java_u2()
2115 // and put_native_u2().
2116 Bytes::put_Java_u2(bcp, new_index);
2117
2118 Relocator rc(method, NULL /* no RelocatorListener needed */);
2119 methodHandle m;
2120 {
2121 PauseNoSafepointVerifier pnsv(&nsv);
2122
2123 // ldc is 2 bytes and ldc_w is 3 bytes
2124 m = rc.insert_space_at(bci, 3, inst_buffer, CHECK);
2125 }
2126
2127 // return the new method so that the caller can update
2128 // the containing class
2129 *new_method_p = method = m;
2130 // switch our bytecode processing loop from the old method
2131 // to the new method
2132 code_base = method->code_base();
2133 code_length = method->code_size();
2134 bcp = code_base + bci;
2135 c = (Bytecodes::Code)(*bcp);
2136 bc_length = Bytecodes::length_for(c);
2137 assert(bc_length != 0, "sanity check");
2138 } // end we need ldc_w instead of ldc
2139 } // end if there is a mapped index
2140 } break;
2141
2142 // these bytecodes have a two-byte constant pool index
2143 case Bytecodes::_anewarray : // fall through
2144 case Bytecodes::_checkcast : // fall through
2145 case Bytecodes::_getfield : // fall through
2146 case Bytecodes::_getstatic : // fall through
2147 case Bytecodes::_instanceof : // fall through
2148 case Bytecodes::_invokedynamic : // fall through
2149 case Bytecodes::_invokeinterface: // fall through
2150 case Bytecodes::_invokespecial : // fall through
2151 case Bytecodes::_invokestatic : // fall through
2152 case Bytecodes::_invokevirtual : // fall through
2153 case Bytecodes::_ldc_w : // fall through
2154 case Bytecodes::_ldc2_w : // fall through
2155 case Bytecodes::_multianewarray : // fall through
2156 case Bytecodes::_new : // fall through
2157 case Bytecodes::_putfield : // fall through
2158 case Bytecodes::_putstatic :
2159 {
2160 address p = bcp + 1;
2161 int cp_index = Bytes::get_Java_u2(p);
2162 int new_index = find_new_index(cp_index);
2163 if (new_index != 0) {
2164 // the original index is mapped so update w/ new value
2165 log_trace(redefine, class, constantpool)
2166 ("%s@" INTPTR_FORMAT " old=%d, new=%d", Bytecodes::name(c),p2i(bcp), cp_index, new_index);
2167 // Rewriter::rewrite_method() uses put_native_u2() in this
2168 // situation because it is reusing the constant pool index
2169 // location for a native index into the ConstantPoolCache.
2170 // Since we are updating the constant pool index prior to
2171 // verification and ConstantPoolCache initialization, we
2172 // need to keep the new index in Java byte order.
2173 Bytes::put_Java_u2(p, new_index);
2174 }
2175 } break;
2176 default:
2177 break;
2178 }
2179 } // end for each bytecode
2180
2181 // We also need to rewrite the parameter name indexes, if there is
2182 // method parameter data present
2183 if(method->has_method_parameters()) {
2184 const int len = method->method_parameters_length();
2185 MethodParametersElement* elem = method->method_parameters_start();
2186
2187 for (int i = 0; i < len; i++) {
2188 const u2 cp_index = elem[i].name_cp_index;
2189 const u2 new_cp_index = find_new_index(cp_index);
2190 if (new_cp_index != 0) {
2191 elem[i].name_cp_index = new_cp_index;
2192 }
2193 }
2194 }
2195 } // end rewrite_cp_refs_in_method()
2196
2197
2198 // Rewrite constant pool references in the class_annotations field.
2199 bool VM_RedefineClasses::rewrite_cp_refs_in_class_annotations(
2200 InstanceKlass* scratch_class, TRAPS) {
2201
2202 AnnotationArray* class_annotations = scratch_class->class_annotations();
2203 if (class_annotations == NULL || class_annotations->length() == 0) {
2204 // no class_annotations so nothing to do
2205 return true;
2206 }
2207
2208 log_debug(redefine, class, annotation)("class_annotations length=%d", class_annotations->length());
2209
2210 int byte_i = 0; // byte index into class_annotations
2211 return rewrite_cp_refs_in_annotations_typeArray(class_annotations, byte_i,
2212 THREAD);
2213 }
2214
2215
2216 // Rewrite constant pool references in an annotations typeArray. This
2217 // "structure" is adapted from the RuntimeVisibleAnnotations_attribute
2218 // that is described in section 4.8.15 of the 2nd-edition of the VM spec:
2219 //
2220 // annotations_typeArray {
2221 // u2 num_annotations;
2222 // annotation annotations[num_annotations];
2223 // }
2224 //
2225 bool VM_RedefineClasses::rewrite_cp_refs_in_annotations_typeArray(
2226 AnnotationArray* annotations_typeArray, int &byte_i_ref, TRAPS) {
2227
2228 if ((byte_i_ref + 2) > annotations_typeArray->length()) {
2229 // not enough room for num_annotations field
2230 log_debug(redefine, class, annotation)("length() is too small for num_annotations field");
2231 return false;
2232 }
2233
2234 u2 num_annotations = Bytes::get_Java_u2((address)
2235 annotations_typeArray->adr_at(byte_i_ref));
2236 byte_i_ref += 2;
2237
2238 log_debug(redefine, class, annotation)("num_annotations=%d", num_annotations);
2239
2240 int calc_num_annotations = 0;
2241 for (; calc_num_annotations < num_annotations; calc_num_annotations++) {
2242 if (!rewrite_cp_refs_in_annotation_struct(annotations_typeArray,
2243 byte_i_ref, THREAD)) {
2244 log_debug(redefine, class, annotation)("bad annotation_struct at %d", calc_num_annotations);
2245 // propagate failure back to caller
2246 return false;
2247 }
2248 }
2249 assert(num_annotations == calc_num_annotations, "sanity check");
2250
2251 return true;
2252 } // end rewrite_cp_refs_in_annotations_typeArray()
2253
2254
2255 // Rewrite constant pool references in the annotation struct portion of
2256 // an annotations_typeArray. This "structure" is from section 4.8.15 of
2257 // the 2nd-edition of the VM spec:
2258 //
2259 // struct annotation {
2260 // u2 type_index;
2261 // u2 num_element_value_pairs;
2262 // {
2263 // u2 element_name_index;
2264 // element_value value;
2265 // } element_value_pairs[num_element_value_pairs];
2266 // }
2267 //
2268 bool VM_RedefineClasses::rewrite_cp_refs_in_annotation_struct(
2269 AnnotationArray* annotations_typeArray, int &byte_i_ref, TRAPS) {
2270 if ((byte_i_ref + 2 + 2) > annotations_typeArray->length()) {
2271 // not enough room for smallest annotation_struct
2272 log_debug(redefine, class, annotation)("length() is too small for annotation_struct");
2273 return false;
2274 }
2275
2276 u2 type_index = rewrite_cp_ref_in_annotation_data(annotations_typeArray,
2277 byte_i_ref, "type_index", THREAD);
2278
2279 u2 num_element_value_pairs = Bytes::get_Java_u2((address)
2280 annotations_typeArray->adr_at(byte_i_ref));
2281 byte_i_ref += 2;
2282
2283 log_debug(redefine, class, annotation)
2284 ("type_index=%d num_element_value_pairs=%d", type_index, num_element_value_pairs);
2285
2286 int calc_num_element_value_pairs = 0;
2287 for (; calc_num_element_value_pairs < num_element_value_pairs;
2288 calc_num_element_value_pairs++) {
2289 if ((byte_i_ref + 2) > annotations_typeArray->length()) {
2290 // not enough room for another element_name_index, let alone
2291 // the rest of another component
2292 log_debug(redefine, class, annotation)("length() is too small for element_name_index");
2293 return false;
2294 }
2295
2296 u2 element_name_index = rewrite_cp_ref_in_annotation_data(
2297 annotations_typeArray, byte_i_ref,
2298 "element_name_index", THREAD);
2299
2300 log_debug(redefine, class, annotation)("element_name_index=%d", element_name_index);
2301
2302 if (!rewrite_cp_refs_in_element_value(annotations_typeArray,
2303 byte_i_ref, THREAD)) {
2304 log_debug(redefine, class, annotation)("bad element_value at %d", calc_num_element_value_pairs);
2305 // propagate failure back to caller
2306 return false;
2307 }
2308 } // end for each component
2309 assert(num_element_value_pairs == calc_num_element_value_pairs,
2310 "sanity check");
2311
2312 return true;
2313 } // end rewrite_cp_refs_in_annotation_struct()
2314
2315
2316 // Rewrite a constant pool reference at the current position in
2317 // annotations_typeArray if needed. Returns the original constant
2318 // pool reference if a rewrite was not needed or the new constant
2319 // pool reference if a rewrite was needed.
2320 u2 VM_RedefineClasses::rewrite_cp_ref_in_annotation_data(
2321 AnnotationArray* annotations_typeArray, int &byte_i_ref,
2322 const char * trace_mesg, TRAPS) {
2323
2324 address cp_index_addr = (address)
2325 annotations_typeArray->adr_at(byte_i_ref);
2326 u2 old_cp_index = Bytes::get_Java_u2(cp_index_addr);
2327 u2 new_cp_index = find_new_index(old_cp_index);
2328 if (new_cp_index != 0) {
2329 log_debug(redefine, class, annotation)("mapped old %s=%d", trace_mesg, old_cp_index);
2330 Bytes::put_Java_u2(cp_index_addr, new_cp_index);
2331 old_cp_index = new_cp_index;
2332 }
2333 byte_i_ref += 2;
2334 return old_cp_index;
2335 }
2336
2337
2338 // Rewrite constant pool references in the element_value portion of an
2339 // annotations_typeArray. This "structure" is from section 4.8.15.1 of
2340 // the 2nd-edition of the VM spec:
2341 //
2342 // struct element_value {
2343 // u1 tag;
2344 // union {
2345 // u2 const_value_index;
2346 // {
2347 // u2 type_name_index;
2348 // u2 const_name_index;
2349 // } enum_const_value;
2350 // u2 class_info_index;
2351 // annotation annotation_value;
2352 // struct {
2353 // u2 num_values;
2354 // element_value values[num_values];
2355 // } array_value;
2356 // } value;
2357 // }
2358 //
2359 bool VM_RedefineClasses::rewrite_cp_refs_in_element_value(
2360 AnnotationArray* annotations_typeArray, int &byte_i_ref, TRAPS) {
2361
2362 if ((byte_i_ref + 1) > annotations_typeArray->length()) {
2363 // not enough room for a tag let alone the rest of an element_value
2364 log_debug(redefine, class, annotation)("length() is too small for a tag");
2365 return false;
2366 }
2367
2368 u1 tag = annotations_typeArray->at(byte_i_ref);
2369 byte_i_ref++;
2370 log_debug(redefine, class, annotation)("tag='%c'", tag);
2371
2372 switch (tag) {
2373 // These BaseType tag values are from Table 4.2 in VM spec:
2374 case JVM_SIGNATURE_BYTE:
2375 case JVM_SIGNATURE_CHAR:
2376 case JVM_SIGNATURE_DOUBLE:
2377 case JVM_SIGNATURE_FLOAT:
2378 case JVM_SIGNATURE_INT:
2379 case JVM_SIGNATURE_LONG:
2380 case JVM_SIGNATURE_SHORT:
2381 case JVM_SIGNATURE_BOOLEAN:
2382
2383 // The remaining tag values are from Table 4.8 in the 2nd-edition of
2384 // the VM spec:
2385 case 's':
2386 {
2387 // For the above tag values (including the BaseType values),
2388 // value.const_value_index is right union field.
2389
2390 if ((byte_i_ref + 2) > annotations_typeArray->length()) {
2391 // not enough room for a const_value_index
2392 log_debug(redefine, class, annotation)("length() is too small for a const_value_index");
2393 return false;
2394 }
2395
2396 u2 const_value_index = rewrite_cp_ref_in_annotation_data(
2397 annotations_typeArray, byte_i_ref,
2398 "const_value_index", THREAD);
2399
2400 log_debug(redefine, class, annotation)("const_value_index=%d", const_value_index);
2401 } break;
2402
2403 case 'e':
2404 {
2405 // for the above tag value, value.enum_const_value is right union field
2406
2407 if ((byte_i_ref + 4) > annotations_typeArray->length()) {
2408 // not enough room for a enum_const_value
2409 log_debug(redefine, class, annotation)("length() is too small for a enum_const_value");
2410 return false;
2411 }
2412
2413 u2 type_name_index = rewrite_cp_ref_in_annotation_data(
2414 annotations_typeArray, byte_i_ref,
2415 "type_name_index", THREAD);
2416
2417 u2 const_name_index = rewrite_cp_ref_in_annotation_data(
2418 annotations_typeArray, byte_i_ref,
2419 "const_name_index", THREAD);
2420
2421 log_debug(redefine, class, annotation)
2422 ("type_name_index=%d const_name_index=%d", type_name_index, const_name_index);
2423 } break;
2424
2425 case 'c':
2426 {
2427 // for the above tag value, value.class_info_index is right union field
2428
2429 if ((byte_i_ref + 2) > annotations_typeArray->length()) {
2430 // not enough room for a class_info_index
2431 log_debug(redefine, class, annotation)("length() is too small for a class_info_index");
2432 return false;
2433 }
2434
2435 u2 class_info_index = rewrite_cp_ref_in_annotation_data(
2436 annotations_typeArray, byte_i_ref,
2437 "class_info_index", THREAD);
2438
2439 log_debug(redefine, class, annotation)("class_info_index=%d", class_info_index);
2440 } break;
2441
2442 case '@':
2443 // For the above tag value, value.attr_value is the right union
2444 // field. This is a nested annotation.
2445 if (!rewrite_cp_refs_in_annotation_struct(annotations_typeArray,
2446 byte_i_ref, THREAD)) {
2447 // propagate failure back to caller
2448 return false;
2449 }
2450 break;
2451
2452 case JVM_SIGNATURE_ARRAY:
2453 {
2454 if ((byte_i_ref + 2) > annotations_typeArray->length()) {
2455 // not enough room for a num_values field
2456 log_debug(redefine, class, annotation)("length() is too small for a num_values field");
2457 return false;
2458 }
2459
2460 // For the above tag value, value.array_value is the right union
2461 // field. This is an array of nested element_value.
2462 u2 num_values = Bytes::get_Java_u2((address)
2463 annotations_typeArray->adr_at(byte_i_ref));
2464 byte_i_ref += 2;
2465 log_debug(redefine, class, annotation)("num_values=%d", num_values);
2466
2467 int calc_num_values = 0;
2468 for (; calc_num_values < num_values; calc_num_values++) {
2469 if (!rewrite_cp_refs_in_element_value(
2470 annotations_typeArray, byte_i_ref, THREAD)) {
2471 log_debug(redefine, class, annotation)("bad nested element_value at %d", calc_num_values);
2472 // propagate failure back to caller
2473 return false;
2474 }
2475 }
2476 assert(num_values == calc_num_values, "sanity check");
2477 } break;
2478
2479 default:
2480 log_debug(redefine, class, annotation)("bad tag=0x%x", tag);
2481 return false;
2482 } // end decode tag field
2483
2484 return true;
2485 } // end rewrite_cp_refs_in_element_value()
2486
2487
2488 // Rewrite constant pool references in a fields_annotations field.
2489 bool VM_RedefineClasses::rewrite_cp_refs_in_fields_annotations(
2490 InstanceKlass* scratch_class, TRAPS) {
2491
2492 Array<AnnotationArray*>* fields_annotations = scratch_class->fields_annotations();
2493
2494 if (fields_annotations == NULL || fields_annotations->length() == 0) {
2495 // no fields_annotations so nothing to do
2496 return true;
2497 }
2498
2499 log_debug(redefine, class, annotation)("fields_annotations length=%d", fields_annotations->length());
2500
2501 for (int i = 0; i < fields_annotations->length(); i++) {
2502 AnnotationArray* field_annotations = fields_annotations->at(i);
2503 if (field_annotations == NULL || field_annotations->length() == 0) {
2504 // this field does not have any annotations so skip it
2505 continue;
2506 }
2507
2508 int byte_i = 0; // byte index into field_annotations
2509 if (!rewrite_cp_refs_in_annotations_typeArray(field_annotations, byte_i,
2510 THREAD)) {
2511 log_debug(redefine, class, annotation)("bad field_annotations at %d", i);
2512 // propagate failure back to caller
2513 return false;
2514 }
2515 }
2516
2517 return true;
2518 } // end rewrite_cp_refs_in_fields_annotations()
2519
2520
2521 // Rewrite constant pool references in a methods_annotations field.
2522 bool VM_RedefineClasses::rewrite_cp_refs_in_methods_annotations(
2523 InstanceKlass* scratch_class, TRAPS) {
2524
2525 for (int i = 0; i < scratch_class->methods()->length(); i++) {
2526 Method* m = scratch_class->methods()->at(i);
2527 AnnotationArray* method_annotations = m->constMethod()->method_annotations();
2528
2529 if (method_annotations == NULL || method_annotations->length() == 0) {
2530 // this method does not have any annotations so skip it
2531 continue;
2532 }
2533
2534 int byte_i = 0; // byte index into method_annotations
2535 if (!rewrite_cp_refs_in_annotations_typeArray(method_annotations, byte_i,
2536 THREAD)) {
2537 log_debug(redefine, class, annotation)("bad method_annotations at %d", i);
2538 // propagate failure back to caller
2539 return false;
2540 }
2541 }
2542
2543 return true;
2544 } // end rewrite_cp_refs_in_methods_annotations()
2545
2546
2547 // Rewrite constant pool references in a methods_parameter_annotations
2548 // field. This "structure" is adapted from the
2549 // RuntimeVisibleParameterAnnotations_attribute described in section
2550 // 4.8.17 of the 2nd-edition of the VM spec:
2551 //
2552 // methods_parameter_annotations_typeArray {
2553 // u1 num_parameters;
2554 // {
2555 // u2 num_annotations;
2556 // annotation annotations[num_annotations];
2557 // } parameter_annotations[num_parameters];
2558 // }
2559 //
2560 bool VM_RedefineClasses::rewrite_cp_refs_in_methods_parameter_annotations(
2561 InstanceKlass* scratch_class, TRAPS) {
2562
2563 for (int i = 0; i < scratch_class->methods()->length(); i++) {
2564 Method* m = scratch_class->methods()->at(i);
2565 AnnotationArray* method_parameter_annotations = m->constMethod()->parameter_annotations();
2566 if (method_parameter_annotations == NULL
2567 || method_parameter_annotations->length() == 0) {
2568 // this method does not have any parameter annotations so skip it
2569 continue;
2570 }
2571
2572 if (method_parameter_annotations->length() < 1) {
2573 // not enough room for a num_parameters field
2574 log_debug(redefine, class, annotation)("length() is too small for a num_parameters field at %d", i);
2575 return false;
2576 }
2577
2578 int byte_i = 0; // byte index into method_parameter_annotations
2579
2580 u1 num_parameters = method_parameter_annotations->at(byte_i);
2581 byte_i++;
2582
2583 log_debug(redefine, class, annotation)("num_parameters=%d", num_parameters);
2584
2585 int calc_num_parameters = 0;
2586 for (; calc_num_parameters < num_parameters; calc_num_parameters++) {
2587 if (!rewrite_cp_refs_in_annotations_typeArray(
2588 method_parameter_annotations, byte_i, THREAD)) {
2589 log_debug(redefine, class, annotation)("bad method_parameter_annotations at %d", calc_num_parameters);
2590 // propagate failure back to caller
2591 return false;
2592 }
2593 }
2594 assert(num_parameters == calc_num_parameters, "sanity check");
2595 }
2596
2597 return true;
2598 } // end rewrite_cp_refs_in_methods_parameter_annotations()
2599
2600
2601 // Rewrite constant pool references in a methods_default_annotations
2602 // field. This "structure" is adapted from the AnnotationDefault_attribute
2603 // that is described in section 4.8.19 of the 2nd-edition of the VM spec:
2604 //
2605 // methods_default_annotations_typeArray {
2606 // element_value default_value;
2607 // }
2608 //
2609 bool VM_RedefineClasses::rewrite_cp_refs_in_methods_default_annotations(
2610 InstanceKlass* scratch_class, TRAPS) {
2611
2612 for (int i = 0; i < scratch_class->methods()->length(); i++) {
2613 Method* m = scratch_class->methods()->at(i);
2614 AnnotationArray* method_default_annotations = m->constMethod()->default_annotations();
2615 if (method_default_annotations == NULL
2616 || method_default_annotations->length() == 0) {
2617 // this method does not have any default annotations so skip it
2618 continue;
2619 }
2620
2621 int byte_i = 0; // byte index into method_default_annotations
2622
2623 if (!rewrite_cp_refs_in_element_value(
2624 method_default_annotations, byte_i, THREAD)) {
2625 log_debug(redefine, class, annotation)("bad default element_value at %d", i);
2626 // propagate failure back to caller
2627 return false;
2628 }
2629 }
2630
2631 return true;
2632 } // end rewrite_cp_refs_in_methods_default_annotations()
2633
2634
2635 // Rewrite constant pool references in a class_type_annotations field.
2636 bool VM_RedefineClasses::rewrite_cp_refs_in_class_type_annotations(
2637 InstanceKlass* scratch_class, TRAPS) {
2638
2639 AnnotationArray* class_type_annotations = scratch_class->class_type_annotations();
2640 if (class_type_annotations == NULL || class_type_annotations->length() == 0) {
2641 // no class_type_annotations so nothing to do
2642 return true;
2643 }
2644
2645 log_debug(redefine, class, annotation)("class_type_annotations length=%d", class_type_annotations->length());
2646
2647 int byte_i = 0; // byte index into class_type_annotations
2648 return rewrite_cp_refs_in_type_annotations_typeArray(class_type_annotations,
2649 byte_i, "ClassFile", THREAD);
2650 } // end rewrite_cp_refs_in_class_type_annotations()
2651
2652
2653 // Rewrite constant pool references in a fields_type_annotations field.
2654 bool VM_RedefineClasses::rewrite_cp_refs_in_fields_type_annotations(
2655 InstanceKlass* scratch_class, TRAPS) {
2656
2657 Array<AnnotationArray*>* fields_type_annotations = scratch_class->fields_type_annotations();
2658 if (fields_type_annotations == NULL || fields_type_annotations->length() == 0) {
2659 // no fields_type_annotations so nothing to do
2660 return true;
2661 }
2662
2663 log_debug(redefine, class, annotation)("fields_type_annotations length=%d", fields_type_annotations->length());
2664
2665 for (int i = 0; i < fields_type_annotations->length(); i++) {
2666 AnnotationArray* field_type_annotations = fields_type_annotations->at(i);
2667 if (field_type_annotations == NULL || field_type_annotations->length() == 0) {
2668 // this field does not have any annotations so skip it
2669 continue;
2670 }
2671
2672 int byte_i = 0; // byte index into field_type_annotations
2673 if (!rewrite_cp_refs_in_type_annotations_typeArray(field_type_annotations,
2674 byte_i, "field_info", THREAD)) {
2675 log_debug(redefine, class, annotation)("bad field_type_annotations at %d", i);
2676 // propagate failure back to caller
2677 return false;
2678 }
2679 }
2680
2681 return true;
2682 } // end rewrite_cp_refs_in_fields_type_annotations()
2683
2684
2685 // Rewrite constant pool references in a methods_type_annotations field.
2686 bool VM_RedefineClasses::rewrite_cp_refs_in_methods_type_annotations(
2687 InstanceKlass* scratch_class, TRAPS) {
2688
2689 for (int i = 0; i < scratch_class->methods()->length(); i++) {
2690 Method* m = scratch_class->methods()->at(i);
2691 AnnotationArray* method_type_annotations = m->constMethod()->type_annotations();
2692
2693 if (method_type_annotations == NULL || method_type_annotations->length() == 0) {
2694 // this method does not have any annotations so skip it
2695 continue;
2696 }
2697
2698 log_debug(redefine, class, annotation)("methods type_annotations length=%d", method_type_annotations->length());
2699
2700 int byte_i = 0; // byte index into method_type_annotations
2701 if (!rewrite_cp_refs_in_type_annotations_typeArray(method_type_annotations,
2702 byte_i, "method_info", THREAD)) {
2703 log_debug(redefine, class, annotation)("bad method_type_annotations at %d", i);
2704 // propagate failure back to caller
2705 return false;
2706 }
2707 }
2708
2709 return true;
2710 } // end rewrite_cp_refs_in_methods_type_annotations()
2711
2712
2713 // Rewrite constant pool references in a type_annotations
2714 // field. This "structure" is adapted from the
2715 // RuntimeVisibleTypeAnnotations_attribute described in
2716 // section 4.7.20 of the Java SE 8 Edition of the VM spec:
2717 //
2718 // type_annotations_typeArray {
2719 // u2 num_annotations;
2720 // type_annotation annotations[num_annotations];
2721 // }
2722 //
2723 bool VM_RedefineClasses::rewrite_cp_refs_in_type_annotations_typeArray(
2724 AnnotationArray* type_annotations_typeArray, int &byte_i_ref,
2725 const char * location_mesg, TRAPS) {
2726
2727 if ((byte_i_ref + 2) > type_annotations_typeArray->length()) {
2728 // not enough room for num_annotations field
2729 log_debug(redefine, class, annotation)("length() is too small for num_annotations field");
2730 return false;
2731 }
2732
2733 u2 num_annotations = Bytes::get_Java_u2((address)
2734 type_annotations_typeArray->adr_at(byte_i_ref));
2735 byte_i_ref += 2;
2736
2737 log_debug(redefine, class, annotation)("num_type_annotations=%d", num_annotations);
2738
2739 int calc_num_annotations = 0;
2740 for (; calc_num_annotations < num_annotations; calc_num_annotations++) {
2741 if (!rewrite_cp_refs_in_type_annotation_struct(type_annotations_typeArray,
2742 byte_i_ref, location_mesg, THREAD)) {
2743 log_debug(redefine, class, annotation)("bad type_annotation_struct at %d", calc_num_annotations);
2744 // propagate failure back to caller
2745 return false;
2746 }
2747 }
2748 assert(num_annotations == calc_num_annotations, "sanity check");
2749
2750 if (byte_i_ref != type_annotations_typeArray->length()) {
2751 log_debug(redefine, class, annotation)
2752 ("read wrong amount of bytes at end of processing type_annotations_typeArray (%d of %d bytes were read)",
2753 byte_i_ref, type_annotations_typeArray->length());
2754 return false;
2755 }
2756
2757 return true;
2758 } // end rewrite_cp_refs_in_type_annotations_typeArray()
2759
2760
2761 // Rewrite constant pool references in a type_annotation
2762 // field. This "structure" is adapted from the
2763 // RuntimeVisibleTypeAnnotations_attribute described in
2764 // section 4.7.20 of the Java SE 8 Edition of the VM spec:
2765 //
2766 // type_annotation {
2767 // u1 target_type;
2768 // union {
2769 // type_parameter_target;
2770 // supertype_target;
2771 // type_parameter_bound_target;
2772 // empty_target;
2773 // method_formal_parameter_target;
2774 // throws_target;
2775 // localvar_target;
2776 // catch_target;
2777 // offset_target;
2778 // type_argument_target;
2779 // } target_info;
2780 // type_path target_path;
2781 // annotation anno;
2782 // }
2783 //
2784 bool VM_RedefineClasses::rewrite_cp_refs_in_type_annotation_struct(
2785 AnnotationArray* type_annotations_typeArray, int &byte_i_ref,
2786 const char * location_mesg, TRAPS) {
2787
2788 if (!skip_type_annotation_target(type_annotations_typeArray,
2789 byte_i_ref, location_mesg, THREAD)) {
2790 return false;
2791 }
2792
2793 if (!skip_type_annotation_type_path(type_annotations_typeArray,
2794 byte_i_ref, THREAD)) {
2795 return false;
2796 }
2797
2798 if (!rewrite_cp_refs_in_annotation_struct(type_annotations_typeArray,
2799 byte_i_ref, THREAD)) {
2800 return false;
2801 }
2802
2803 return true;
2804 } // end rewrite_cp_refs_in_type_annotation_struct()
2805
2806
2807 // Read, verify and skip over the target_type and target_info part
2808 // so that rewriting can continue in the later parts of the struct.
2809 //
2810 // u1 target_type;
2811 // union {
2812 // type_parameter_target;
2813 // supertype_target;
2814 // type_parameter_bound_target;
2815 // empty_target;
2816 // method_formal_parameter_target;
2817 // throws_target;
2818 // localvar_target;
2819 // catch_target;
2820 // offset_target;
2821 // type_argument_target;
2822 // } target_info;
2823 //
2824 bool VM_RedefineClasses::skip_type_annotation_target(
2825 AnnotationArray* type_annotations_typeArray, int &byte_i_ref,
2826 const char * location_mesg, TRAPS) {
2827
2828 if ((byte_i_ref + 1) > type_annotations_typeArray->length()) {
2829 // not enough room for a target_type let alone the rest of a type_annotation
2830 log_debug(redefine, class, annotation)("length() is too small for a target_type");
2831 return false;
2832 }
2833
2834 u1 target_type = type_annotations_typeArray->at(byte_i_ref);
2835 byte_i_ref += 1;
2836 log_debug(redefine, class, annotation)("target_type=0x%.2x", target_type);
2837 log_debug(redefine, class, annotation)("location=%s", location_mesg);
2838
2839 // Skip over target_info
2840 switch (target_type) {
2841 case 0x00:
2842 // kind: type parameter declaration of generic class or interface
2843 // location: ClassFile
2844 case 0x01:
2845 // kind: type parameter declaration of generic method or constructor
2846 // location: method_info
2847
2848 {
2849 // struct:
2850 // type_parameter_target {
2851 // u1 type_parameter_index;
2852 // }
2853 //
2854 if ((byte_i_ref + 1) > type_annotations_typeArray->length()) {
2855 log_debug(redefine, class, annotation)("length() is too small for a type_parameter_target");
2856 return false;
2857 }
2858
2859 u1 type_parameter_index = type_annotations_typeArray->at(byte_i_ref);
2860 byte_i_ref += 1;
2861
2862 log_debug(redefine, class, annotation)("type_parameter_target: type_parameter_index=%d", type_parameter_index);
2863 } break;
2864
2865 case 0x10:
2866 // kind: type in extends clause of class or interface declaration
2867 // (including the direct superclass of an unsafe anonymous class declaration),
2868 // or in implements clause of interface declaration
2869 // location: ClassFile
2870
2871 {
2872 // struct:
2873 // supertype_target {
2874 // u2 supertype_index;
2875 // }
2876 //
2877 if ((byte_i_ref + 2) > type_annotations_typeArray->length()) {
2878 log_debug(redefine, class, annotation)("length() is too small for a supertype_target");
2879 return false;
2880 }
2881
2882 u2 supertype_index = Bytes::get_Java_u2((address)
2883 type_annotations_typeArray->adr_at(byte_i_ref));
2884 byte_i_ref += 2;
2885
2886 log_debug(redefine, class, annotation)("supertype_target: supertype_index=%d", supertype_index);
2887 } break;
2888
2889 case 0x11:
2890 // kind: type in bound of type parameter declaration of generic class or interface
2891 // location: ClassFile
2892 case 0x12:
2893 // kind: type in bound of type parameter declaration of generic method or constructor
2894 // location: method_info
2895
2896 {
2897 // struct:
2898 // type_parameter_bound_target {
2899 // u1 type_parameter_index;
2900 // u1 bound_index;
2901 // }
2902 //
2903 if ((byte_i_ref + 2) > type_annotations_typeArray->length()) {
2904 log_debug(redefine, class, annotation)("length() is too small for a type_parameter_bound_target");
2905 return false;
2906 }
2907
2908 u1 type_parameter_index = type_annotations_typeArray->at(byte_i_ref);
2909 byte_i_ref += 1;
2910 u1 bound_index = type_annotations_typeArray->at(byte_i_ref);
2911 byte_i_ref += 1;
2912
2913 log_debug(redefine, class, annotation)
2914 ("type_parameter_bound_target: type_parameter_index=%d, bound_index=%d", type_parameter_index, bound_index);
2915 } break;
2916
2917 case 0x13:
2918 // kind: type in field declaration
2919 // location: field_info
2920 case 0x14:
2921 // kind: return type of method, or type of newly constructed object
2922 // location: method_info
2923 case 0x15:
2924 // kind: receiver type of method or constructor
2925 // location: method_info
2926
2927 {
2928 // struct:
2929 // empty_target {
2930 // }
2931 //
2932 log_debug(redefine, class, annotation)("empty_target");
2933 } break;
2934
2935 case 0x16:
2936 // kind: type in formal parameter declaration of method, constructor, or lambda expression
2937 // location: method_info
2938
2939 {
2940 // struct:
2941 // formal_parameter_target {
2942 // u1 formal_parameter_index;
2943 // }
2944 //
2945 if ((byte_i_ref + 1) > type_annotations_typeArray->length()) {
2946 log_debug(redefine, class, annotation)("length() is too small for a formal_parameter_target");
2947 return false;
2948 }
2949
2950 u1 formal_parameter_index = type_annotations_typeArray->at(byte_i_ref);
2951 byte_i_ref += 1;
2952
2953 log_debug(redefine, class, annotation)
2954 ("formal_parameter_target: formal_parameter_index=%d", formal_parameter_index);
2955 } break;
2956
2957 case 0x17:
2958 // kind: type in throws clause of method or constructor
2959 // location: method_info
2960
2961 {
2962 // struct:
2963 // throws_target {
2964 // u2 throws_type_index
2965 // }
2966 //
2967 if ((byte_i_ref + 2) > type_annotations_typeArray->length()) {
2968 log_debug(redefine, class, annotation)("length() is too small for a throws_target");
2969 return false;
2970 }
2971
2972 u2 throws_type_index = Bytes::get_Java_u2((address)
2973 type_annotations_typeArray->adr_at(byte_i_ref));
2974 byte_i_ref += 2;
2975
2976 log_debug(redefine, class, annotation)("throws_target: throws_type_index=%d", throws_type_index);
2977 } break;
2978
2979 case 0x40:
2980 // kind: type in local variable declaration
2981 // location: Code
2982 case 0x41:
2983 // kind: type in resource variable declaration
2984 // location: Code
2985
2986 {
2987 // struct:
2988 // localvar_target {
2989 // u2 table_length;
2990 // struct {
2991 // u2 start_pc;
2992 // u2 length;
2993 // u2 index;
2994 // } table[table_length];
2995 // }
2996 //
2997 if ((byte_i_ref + 2) > type_annotations_typeArray->length()) {
2998 // not enough room for a table_length let alone the rest of a localvar_target
2999 log_debug(redefine, class, annotation)("length() is too small for a localvar_target table_length");
3000 return false;
3001 }
3002
3003 u2 table_length = Bytes::get_Java_u2((address)
3004 type_annotations_typeArray->adr_at(byte_i_ref));
3005 byte_i_ref += 2;
3006
3007 log_debug(redefine, class, annotation)("localvar_target: table_length=%d", table_length);
3008
3009 int table_struct_size = 2 + 2 + 2; // 3 u2 variables per table entry
3010 int table_size = table_length * table_struct_size;
3011
3012 if ((byte_i_ref + table_size) > type_annotations_typeArray->length()) {
3013 // not enough room for a table
3014 log_debug(redefine, class, annotation)("length() is too small for a table array of length %d", table_length);
3015 return false;
3016 }
3017
3018 // Skip over table
3019 byte_i_ref += table_size;
3020 } break;
3021
3022 case 0x42:
3023 // kind: type in exception parameter declaration
3024 // location: Code
3025
3026 {
3027 // struct:
3028 // catch_target {
3029 // u2 exception_table_index;
3030 // }
3031 //
3032 if ((byte_i_ref + 2) > type_annotations_typeArray->length()) {
3033 log_debug(redefine, class, annotation)("length() is too small for a catch_target");
3034 return false;
3035 }
3036
3037 u2 exception_table_index = Bytes::get_Java_u2((address)
3038 type_annotations_typeArray->adr_at(byte_i_ref));
3039 byte_i_ref += 2;
3040
3041 log_debug(redefine, class, annotation)("catch_target: exception_table_index=%d", exception_table_index);
3042 } break;
3043
3044 case 0x43:
3045 // kind: type in instanceof expression
3046 // location: Code
3047 case 0x44:
3048 // kind: type in new expression
3049 // location: Code
3050 case 0x45:
3051 // kind: type in method reference expression using ::new
3052 // location: Code
3053 case 0x46:
3054 // kind: type in method reference expression using ::Identifier
3055 // location: Code
3056
3057 {
3058 // struct:
3059 // offset_target {
3060 // u2 offset;
3061 // }
3062 //
3063 if ((byte_i_ref + 2) > type_annotations_typeArray->length()) {
3064 log_debug(redefine, class, annotation)("length() is too small for a offset_target");
3065 return false;
3066 }
3067
3068 u2 offset = Bytes::get_Java_u2((address)
3069 type_annotations_typeArray->adr_at(byte_i_ref));
3070 byte_i_ref += 2;
3071
3072 log_debug(redefine, class, annotation)("offset_target: offset=%d", offset);
3073 } break;
3074
3075 case 0x47:
3076 // kind: type in cast expression
3077 // location: Code
3078 case 0x48:
3079 // kind: type argument for generic constructor in new expression or
3080 // explicit constructor invocation statement
3081 // location: Code
3082 case 0x49:
3083 // kind: type argument for generic method in method invocation expression
3084 // location: Code
3085 case 0x4A:
3086 // kind: type argument for generic constructor in method reference expression using ::new
3087 // location: Code
3088 case 0x4B:
3089 // kind: type argument for generic method in method reference expression using ::Identifier
3090 // location: Code
3091
3092 {
3093 // struct:
3094 // type_argument_target {
3095 // u2 offset;
3096 // u1 type_argument_index;
3097 // }
3098 //
3099 if ((byte_i_ref + 3) > type_annotations_typeArray->length()) {
3100 log_debug(redefine, class, annotation)("length() is too small for a type_argument_target");
3101 return false;
3102 }
3103
3104 u2 offset = Bytes::get_Java_u2((address)
3105 type_annotations_typeArray->adr_at(byte_i_ref));
3106 byte_i_ref += 2;
3107 u1 type_argument_index = type_annotations_typeArray->at(byte_i_ref);
3108 byte_i_ref += 1;
3109
3110 log_debug(redefine, class, annotation)
3111 ("type_argument_target: offset=%d, type_argument_index=%d", offset, type_argument_index);
3112 } break;
3113
3114 default:
3115 log_debug(redefine, class, annotation)("unknown target_type");
3116 #ifdef ASSERT
3117 ShouldNotReachHere();
3118 #endif
3119 return false;
3120 }
3121
3122 return true;
3123 } // end skip_type_annotation_target()
3124
3125
3126 // Read, verify and skip over the type_path part so that rewriting
3127 // can continue in the later parts of the struct.
3128 //
3129 // type_path {
3130 // u1 path_length;
3131 // {
3132 // u1 type_path_kind;
3133 // u1 type_argument_index;
3134 // } path[path_length];
3135 // }
3136 //
3137 bool VM_RedefineClasses::skip_type_annotation_type_path(
3138 AnnotationArray* type_annotations_typeArray, int &byte_i_ref, TRAPS) {
3139
3140 if ((byte_i_ref + 1) > type_annotations_typeArray->length()) {
3141 // not enough room for a path_length let alone the rest of the type_path
3142 log_debug(redefine, class, annotation)("length() is too small for a type_path");
3143 return false;
3144 }
3145
3146 u1 path_length = type_annotations_typeArray->at(byte_i_ref);
3147 byte_i_ref += 1;
3148
3149 log_debug(redefine, class, annotation)("type_path: path_length=%d", path_length);
3150
3151 int calc_path_length = 0;
3152 for (; calc_path_length < path_length; calc_path_length++) {
3153 if ((byte_i_ref + 1 + 1) > type_annotations_typeArray->length()) {
3154 // not enough room for a path
3155 log_debug(redefine, class, annotation)
3156 ("length() is too small for path entry %d of %d", calc_path_length, path_length);
3157 return false;
3158 }
3159
3160 u1 type_path_kind = type_annotations_typeArray->at(byte_i_ref);
3161 byte_i_ref += 1;
3162 u1 type_argument_index = type_annotations_typeArray->at(byte_i_ref);
3163 byte_i_ref += 1;
3164
3165 log_debug(redefine, class, annotation)
3166 ("type_path: path[%d]: type_path_kind=%d, type_argument_index=%d",
3167 calc_path_length, type_path_kind, type_argument_index);
3168
3169 if (type_path_kind > 3 || (type_path_kind != 3 && type_argument_index != 0)) {
3170 // not enough room for a path
3171 log_debug(redefine, class, annotation)("inconsistent type_path values");
3172 return false;
3173 }
3174 }
3175 assert(path_length == calc_path_length, "sanity check");
3176
3177 return true;
3178 } // end skip_type_annotation_type_path()
3179
3180
3181 // Rewrite constant pool references in the method's stackmap table.
3182 // These "structures" are adapted from the StackMapTable_attribute that
3183 // is described in section 4.8.4 of the 6.0 version of the VM spec
3184 // (dated 2005.10.26):
3185 // file:///net/quincunx.sfbay/export/gbracha/ClassFile-Java6.pdf
3186 //
3187 // stack_map {
3188 // u2 number_of_entries;
3189 // stack_map_frame entries[number_of_entries];
3190 // }
3191 //
3192 void VM_RedefineClasses::rewrite_cp_refs_in_stack_map_table(
3193 const methodHandle& method, TRAPS) {
3194
3195 if (!method->has_stackmap_table()) {
3196 return;
3197 }
3198
3199 AnnotationArray* stackmap_data = method->stackmap_data();
3200 address stackmap_p = (address)stackmap_data->adr_at(0);
3201 address stackmap_end = stackmap_p + stackmap_data->length();
3202
3203 assert(stackmap_p + 2 <= stackmap_end, "no room for number_of_entries");
3204 u2 number_of_entries = Bytes::get_Java_u2(stackmap_p);
3205 stackmap_p += 2;
3206
3207 log_debug(redefine, class, stackmap)("number_of_entries=%u", number_of_entries);
3208
3209 // walk through each stack_map_frame
3210 u2 calc_number_of_entries = 0;
3211 for (; calc_number_of_entries < number_of_entries; calc_number_of_entries++) {
3212 // The stack_map_frame structure is a u1 frame_type followed by
3213 // 0 or more bytes of data:
3214 //
3215 // union stack_map_frame {
3216 // same_frame;
3217 // same_locals_1_stack_item_frame;
3218 // same_locals_1_stack_item_frame_extended;
3219 // chop_frame;
3220 // same_frame_extended;
3221 // append_frame;
3222 // full_frame;
3223 // }
3224
3225 assert(stackmap_p + 1 <= stackmap_end, "no room for frame_type");
3226 u1 frame_type = *stackmap_p;
3227 stackmap_p++;
3228
3229 // same_frame {
3230 // u1 frame_type = SAME; /* 0-63 */
3231 // }
3232 if (frame_type <= 63) {
3233 // nothing more to do for same_frame
3234 }
3235
3236 // same_locals_1_stack_item_frame {
3237 // u1 frame_type = SAME_LOCALS_1_STACK_ITEM; /* 64-127 */
3238 // verification_type_info stack[1];
3239 // }
3240 else if (frame_type >= 64 && frame_type <= 127) {
3241 rewrite_cp_refs_in_verification_type_info(stackmap_p, stackmap_end,
3242 calc_number_of_entries, frame_type, THREAD);
3243 }
3244
3245 // reserved for future use
3246 else if (frame_type >= 128 && frame_type <= 246) {
3247 // nothing more to do for reserved frame_types
3248 }
3249
3250 // same_locals_1_stack_item_frame_extended {
3251 // u1 frame_type = SAME_LOCALS_1_STACK_ITEM_EXTENDED; /* 247 */
3252 // u2 offset_delta;
3253 // verification_type_info stack[1];
3254 // }
3255 else if (frame_type == 247) {
3256 stackmap_p += 2;
3257 rewrite_cp_refs_in_verification_type_info(stackmap_p, stackmap_end,
3258 calc_number_of_entries, frame_type, THREAD);
3259 }
3260
3261 // chop_frame {
3262 // u1 frame_type = CHOP; /* 248-250 */
3263 // u2 offset_delta;
3264 // }
3265 else if (frame_type >= 248 && frame_type <= 250) {
3266 stackmap_p += 2;
3267 }
3268
3269 // same_frame_extended {
3270 // u1 frame_type = SAME_FRAME_EXTENDED; /* 251*/
3271 // u2 offset_delta;
3272 // }
3273 else if (frame_type == 251) {
3274 stackmap_p += 2;
3275 }
3276
3277 // append_frame {
3278 // u1 frame_type = APPEND; /* 252-254 */
3279 // u2 offset_delta;
3280 // verification_type_info locals[frame_type - 251];
3281 // }
3282 else if (frame_type >= 252 && frame_type <= 254) {
3283 assert(stackmap_p + 2 <= stackmap_end,
3284 "no room for offset_delta");
3285 stackmap_p += 2;
3286 u1 len = frame_type - 251;
3287 for (u1 i = 0; i < len; i++) {
3288 rewrite_cp_refs_in_verification_type_info(stackmap_p, stackmap_end,
3289 calc_number_of_entries, frame_type, THREAD);
3290 }
3291 }
3292
3293 // full_frame {
3294 // u1 frame_type = FULL_FRAME; /* 255 */
3295 // u2 offset_delta;
3296 // u2 number_of_locals;
3297 // verification_type_info locals[number_of_locals];
3298 // u2 number_of_stack_items;
3299 // verification_type_info stack[number_of_stack_items];
3300 // }
3301 else if (frame_type == 255) {
3302 assert(stackmap_p + 2 + 2 <= stackmap_end,
3303 "no room for smallest full_frame");
3304 stackmap_p += 2;
3305
3306 u2 number_of_locals = Bytes::get_Java_u2(stackmap_p);
3307 stackmap_p += 2;
3308
3309 for (u2 locals_i = 0; locals_i < number_of_locals; locals_i++) {
3310 rewrite_cp_refs_in_verification_type_info(stackmap_p, stackmap_end,
3311 calc_number_of_entries, frame_type, THREAD);
3312 }
3313
3314 // Use the largest size for the number_of_stack_items, but only get
3315 // the right number of bytes.
3316 u2 number_of_stack_items = Bytes::get_Java_u2(stackmap_p);
3317 stackmap_p += 2;
3318
3319 for (u2 stack_i = 0; stack_i < number_of_stack_items; stack_i++) {
3320 rewrite_cp_refs_in_verification_type_info(stackmap_p, stackmap_end,
3321 calc_number_of_entries, frame_type, THREAD);
3322 }
3323 }
3324 } // end while there is a stack_map_frame
3325 assert(number_of_entries == calc_number_of_entries, "sanity check");
3326 } // end rewrite_cp_refs_in_stack_map_table()
3327
3328
3329 // Rewrite constant pool references in the verification type info
3330 // portion of the method's stackmap table. These "structures" are
3331 // adapted from the StackMapTable_attribute that is described in
3332 // section 4.8.4 of the 6.0 version of the VM spec (dated 2005.10.26):
3333 // file:///net/quincunx.sfbay/export/gbracha/ClassFile-Java6.pdf
3334 //
3335 // The verification_type_info structure is a u1 tag followed by 0 or
3336 // more bytes of data:
3337 //
3338 // union verification_type_info {
3339 // Top_variable_info;
3340 // Integer_variable_info;
3341 // Float_variable_info;
3342 // Long_variable_info;
3343 // Double_variable_info;
3344 // Null_variable_info;
3345 // UninitializedThis_variable_info;
3346 // Object_variable_info;
3347 // Uninitialized_variable_info;
3348 // }
3349 //
3350 void VM_RedefineClasses::rewrite_cp_refs_in_verification_type_info(
3351 address& stackmap_p_ref, address stackmap_end, u2 frame_i,
3352 u1 frame_type, TRAPS) {
3353
3354 assert(stackmap_p_ref + 1 <= stackmap_end, "no room for tag");
3355 u1 tag = *stackmap_p_ref;
3356 stackmap_p_ref++;
3357
3358 switch (tag) {
3359 // Top_variable_info {
3360 // u1 tag = ITEM_Top; /* 0 */
3361 // }
3362 // verificationType.hpp has zero as ITEM_Bogus instead of ITEM_Top
3363 case 0: // fall through
3364
3365 // Integer_variable_info {
3366 // u1 tag = ITEM_Integer; /* 1 */
3367 // }
3368 case ITEM_Integer: // fall through
3369
3370 // Float_variable_info {
3371 // u1 tag = ITEM_Float; /* 2 */
3372 // }
3373 case ITEM_Float: // fall through
3374
3375 // Double_variable_info {
3376 // u1 tag = ITEM_Double; /* 3 */
3377 // }
3378 case ITEM_Double: // fall through
3379
3380 // Long_variable_info {
3381 // u1 tag = ITEM_Long; /* 4 */
3382 // }
3383 case ITEM_Long: // fall through
3384
3385 // Null_variable_info {
3386 // u1 tag = ITEM_Null; /* 5 */
3387 // }
3388 case ITEM_Null: // fall through
3389
3390 // UninitializedThis_variable_info {
3391 // u1 tag = ITEM_UninitializedThis; /* 6 */
3392 // }
3393 case ITEM_UninitializedThis:
3394 // nothing more to do for the above tag types
3395 break;
3396
3397 // Object_variable_info {
3398 // u1 tag = ITEM_Object; /* 7 */
3399 // u2 cpool_index;
3400 // }
3401 case ITEM_Object:
3402 {
3403 assert(stackmap_p_ref + 2 <= stackmap_end, "no room for cpool_index");
3404 u2 cpool_index = Bytes::get_Java_u2(stackmap_p_ref);
3405 u2 new_cp_index = find_new_index(cpool_index);
3406 if (new_cp_index != 0) {
3407 log_debug(redefine, class, stackmap)("mapped old cpool_index=%d", cpool_index);
3408 Bytes::put_Java_u2(stackmap_p_ref, new_cp_index);
3409 cpool_index = new_cp_index;
3410 }
3411 stackmap_p_ref += 2;
3412
3413 log_debug(redefine, class, stackmap)
3414 ("frame_i=%u, frame_type=%u, cpool_index=%d", frame_i, frame_type, cpool_index);
3415 } break;
3416
3417 // Uninitialized_variable_info {
3418 // u1 tag = ITEM_Uninitialized; /* 8 */
3419 // u2 offset;
3420 // }
3421 case ITEM_Uninitialized:
3422 assert(stackmap_p_ref + 2 <= stackmap_end, "no room for offset");
3423 stackmap_p_ref += 2;
3424 break;
3425
3426 default:
3427 log_debug(redefine, class, stackmap)("frame_i=%u, frame_type=%u, bad tag=0x%x", frame_i, frame_type, tag);
3428 ShouldNotReachHere();
3429 break;
3430 } // end switch (tag)
3431 } // end rewrite_cp_refs_in_verification_type_info()
3432
3433
3434 // Change the constant pool associated with klass scratch_class to
3435 // scratch_cp. If shrink is true, then scratch_cp_length elements
3436 // are copied from scratch_cp to a smaller constant pool and the
3437 // smaller constant pool is associated with scratch_class.
3438 void VM_RedefineClasses::set_new_constant_pool(
3439 ClassLoaderData* loader_data,
3440 InstanceKlass* scratch_class, constantPoolHandle scratch_cp,
3441 int scratch_cp_length, TRAPS) {
3442 assert(scratch_cp->length() >= scratch_cp_length, "sanity check");
3443
3444 // scratch_cp is a merged constant pool and has enough space for a
3445 // worst case merge situation. We want to associate the minimum
3446 // sized constant pool with the klass to save space.
3447 ConstantPool* cp = ConstantPool::allocate(loader_data, scratch_cp_length, CHECK);
3448 constantPoolHandle smaller_cp(THREAD, cp);
3449
3450 // preserve version() value in the smaller copy
3451 int version = scratch_cp->version();
3452 assert(version != 0, "sanity check");
3453 smaller_cp->set_version(version);
3454
3455 // attach klass to new constant pool
3456 // reference to the cp holder is needed for copy_operands()
3457 smaller_cp->set_pool_holder(scratch_class);
3458
3459 smaller_cp->copy_fields(scratch_cp());
3460
3461 scratch_cp->copy_cp_to(1, scratch_cp_length - 1, smaller_cp, 1, THREAD);
3462 if (HAS_PENDING_EXCEPTION) {
3463 // Exception is handled in the caller
3464 loader_data->add_to_deallocate_list(smaller_cp());
3465 return;
3466 }
3467 scratch_cp = smaller_cp;
3468
3469 // attach new constant pool to klass
3470 scratch_class->set_constants(scratch_cp());
3471 scratch_cp->initialize_unresolved_klasses(loader_data, CHECK);
3472
3473 int i; // for portability
3474
3475 // update each field in klass to use new constant pool indices as needed
3476 for (JavaFieldStream fs(scratch_class); !fs.done(); fs.next()) {
3477 jshort cur_index = fs.name_index();
3478 jshort new_index = find_new_index(cur_index);
3479 if (new_index != 0) {
3480 log_trace(redefine, class, constantpool)("field-name_index change: %d to %d", cur_index, new_index);
3481 fs.set_name_index(new_index);
3482 }
3483 cur_index = fs.signature_index();
3484 new_index = find_new_index(cur_index);
3485 if (new_index != 0) {
3486 log_trace(redefine, class, constantpool)("field-signature_index change: %d to %d", cur_index, new_index);
3487 fs.set_signature_index(new_index);
3488 }
3489 cur_index = fs.initval_index();
3490 new_index = find_new_index(cur_index);
3491 if (new_index != 0) {
3492 log_trace(redefine, class, constantpool)("field-initval_index change: %d to %d", cur_index, new_index);
3493 fs.set_initval_index(new_index);
3494 }
3495 cur_index = fs.generic_signature_index();
3496 new_index = find_new_index(cur_index);
3497 if (new_index != 0) {
3498 log_trace(redefine, class, constantpool)("field-generic_signature change: %d to %d", cur_index, new_index);
3499 fs.set_generic_signature_index(new_index);
3500 }
3501 } // end for each field
3502
3503 // Update constant pool indices in the inner classes info to use
3504 // new constant indices as needed. The inner classes info is a
3505 // quadruple:
3506 // (inner_class_info, outer_class_info, inner_name, inner_access_flags)
3507 InnerClassesIterator iter(scratch_class);
3508 for (; !iter.done(); iter.next()) {
3509 int cur_index = iter.inner_class_info_index();
3510 if (cur_index == 0) {
3511 continue; // JVM spec. allows null inner class refs so skip it
3512 }
3513 int new_index = find_new_index(cur_index);
3514 if (new_index != 0) {
3515 log_trace(redefine, class, constantpool)("inner_class_info change: %d to %d", cur_index, new_index);
3516 iter.set_inner_class_info_index(new_index);
3517 }
3518 cur_index = iter.outer_class_info_index();
3519 new_index = find_new_index(cur_index);
3520 if (new_index != 0) {
3521 log_trace(redefine, class, constantpool)("outer_class_info change: %d to %d", cur_index, new_index);
3522 iter.set_outer_class_info_index(new_index);
3523 }
3524 cur_index = iter.inner_name_index();
3525 new_index = find_new_index(cur_index);
3526 if (new_index != 0) {
3527 log_trace(redefine, class, constantpool)("inner_name change: %d to %d", cur_index, new_index);
3528 iter.set_inner_name_index(new_index);
3529 }
3530 } // end for each inner class
3531
3532 // Attach each method in klass to the new constant pool and update
3533 // to use new constant pool indices as needed:
3534 Array<Method*>* methods = scratch_class->methods();
3535 for (i = methods->length() - 1; i >= 0; i--) {
3536 methodHandle method(THREAD, methods->at(i));
3537 method->set_constants(scratch_cp());
3538
3539 int new_index = find_new_index(method->name_index());
3540 if (new_index != 0) {
3541 log_trace(redefine, class, constantpool)
3542 ("method-name_index change: %d to %d", method->name_index(), new_index);
3543 method->set_name_index(new_index);
3544 }
3545 new_index = find_new_index(method->signature_index());
3546 if (new_index != 0) {
3547 log_trace(redefine, class, constantpool)
3548 ("method-signature_index change: %d to %d", method->signature_index(), new_index);
3549 method->set_signature_index(new_index);
3550 }
3551 new_index = find_new_index(method->generic_signature_index());
3552 if (new_index != 0) {
3553 log_trace(redefine, class, constantpool)
3554 ("method-generic_signature_index change: %d to %d", method->generic_signature_index(), new_index);
3555 method->set_generic_signature_index(new_index);
3556 }
3557
3558 // Update constant pool indices in the method's checked exception
3559 // table to use new constant indices as needed.
3560 int cext_length = method->checked_exceptions_length();
3561 if (cext_length > 0) {
3562 CheckedExceptionElement * cext_table =
3563 method->checked_exceptions_start();
3564 for (int j = 0; j < cext_length; j++) {
3565 int cur_index = cext_table[j].class_cp_index;
3566 int new_index = find_new_index(cur_index);
3567 if (new_index != 0) {
3568 log_trace(redefine, class, constantpool)("cext-class_cp_index change: %d to %d", cur_index, new_index);
3569 cext_table[j].class_cp_index = (u2)new_index;
3570 }
3571 } // end for each checked exception table entry
3572 } // end if there are checked exception table entries
3573
3574 // Update each catch type index in the method's exception table
3575 // to use new constant pool indices as needed. The exception table
3576 // holds quadruple entries of the form:
3577 // (beg_bci, end_bci, handler_bci, klass_index)
3578
3579 ExceptionTable ex_table(method());
3580 int ext_length = ex_table.length();
3581
3582 for (int j = 0; j < ext_length; j ++) {
3583 int cur_index = ex_table.catch_type_index(j);
3584 int new_index = find_new_index(cur_index);
3585 if (new_index != 0) {
3586 log_trace(redefine, class, constantpool)("ext-klass_index change: %d to %d", cur_index, new_index);
3587 ex_table.set_catch_type_index(j, new_index);
3588 }
3589 } // end for each exception table entry
3590
3591 // Update constant pool indices in the method's local variable
3592 // table to use new constant indices as needed. The local variable
3593 // table hold sextuple entries of the form:
3594 // (start_pc, length, name_index, descriptor_index, signature_index, slot)
3595 int lvt_length = method->localvariable_table_length();
3596 if (lvt_length > 0) {
3597 LocalVariableTableElement * lv_table =
3598 method->localvariable_table_start();
3599 for (int j = 0; j < lvt_length; j++) {
3600 int cur_index = lv_table[j].name_cp_index;
3601 int new_index = find_new_index(cur_index);
3602 if (new_index != 0) {
3603 log_trace(redefine, class, constantpool)("lvt-name_cp_index change: %d to %d", cur_index, new_index);
3604 lv_table[j].name_cp_index = (u2)new_index;
3605 }
3606 cur_index = lv_table[j].descriptor_cp_index;
3607 new_index = find_new_index(cur_index);
3608 if (new_index != 0) {
3609 log_trace(redefine, class, constantpool)("lvt-descriptor_cp_index change: %d to %d", cur_index, new_index);
3610 lv_table[j].descriptor_cp_index = (u2)new_index;
3611 }
3612 cur_index = lv_table[j].signature_cp_index;
3613 new_index = find_new_index(cur_index);
3614 if (new_index != 0) {
3615 log_trace(redefine, class, constantpool)("lvt-signature_cp_index change: %d to %d", cur_index, new_index);
3616 lv_table[j].signature_cp_index = (u2)new_index;
3617 }
3618 } // end for each local variable table entry
3619 } // end if there are local variable table entries
3620
3621 rewrite_cp_refs_in_stack_map_table(method, THREAD);
3622 } // end for each method
3623 } // end set_new_constant_pool()
3624
3625
3626 // Unevolving classes may point to methods of the_class directly
3627 // from their constant pool caches, itables, and/or vtables. We
3628 // use the ClassLoaderDataGraph::classes_do() facility and this helper
3629 // to fix up these pointers. MethodData also points to old methods and
3630 // must be cleaned.
3631
3632 // Adjust cpools and vtables closure
3633 void VM_RedefineClasses::AdjustAndCleanMetadata::do_klass(Klass* k) {
3634
3635 // This is a very busy routine. We don't want too much tracing
3636 // printed out.
3637 bool trace_name_printed = false;
3638
3639 // If the class being redefined is java.lang.Object, we need to fix all
3640 // array class vtables also
3641 if (k->is_array_klass() && _has_redefined_Object) {
3642 k->vtable().adjust_method_entries(&trace_name_printed);
3643
3644 } else if (k->is_instance_klass()) {
3645 HandleMark hm(_thread);
3646 InstanceKlass *ik = InstanceKlass::cast(k);
3647
3648 // Clean MethodData of this class's methods so they don't refer to
3649 // old methods that are no longer running.
3650 Array<Method*>* methods = ik->methods();
3651 int num_methods = methods->length();
3652 for (int index = 0; index < num_methods; ++index) {
3653 if (methods->at(index)->method_data() != NULL) {
3654 methods->at(index)->method_data()->clean_weak_method_links();
3655 }
3656 }
3657
3658 // HotSpot specific optimization! HotSpot does not currently
3659 // support delegation from the bootstrap class loader to a
3660 // user-defined class loader. This means that if the bootstrap
3661 // class loader is the initiating class loader, then it will also
3662 // be the defining class loader. This also means that classes
3663 // loaded by the bootstrap class loader cannot refer to classes
3664 // loaded by a user-defined class loader. Note: a user-defined
3665 // class loader can delegate to the bootstrap class loader.
3666 //
3667 // If the current class being redefined has a user-defined class
3668 // loader as its defining class loader, then we can skip all
3669 // classes loaded by the bootstrap class loader.
3670 if (!_has_null_class_loader && ik->class_loader() == NULL) {
3671 return;
3672 }
3673
3674 // Adjust all vtables, default methods and itables, to clean out old methods.
3675 ResourceMark rm(_thread);
3676 if (ik->vtable_length() > 0) {
3677 ik->vtable().adjust_method_entries(&trace_name_printed);
3678 ik->adjust_default_methods(&trace_name_printed);
3679 }
3680
3681 if (ik->itable_length() > 0) {
3682 ik->itable().adjust_method_entries(&trace_name_printed);
3683 }
3684
3685 // The constant pools in other classes (other_cp) can refer to
3686 // old methods. We have to update method information in
3687 // other_cp's cache. If other_cp has a previous version, then we
3688 // have to repeat the process for each previous version. The
3689 // constant pool cache holds the Method*s for non-virtual
3690 // methods and for virtual, final methods.
3691 //
3692 // Special case: if the current class being redefined, then new_cp
3693 // has already been attached to the_class and old_cp has already
3694 // been added as a previous version. The new_cp doesn't have any
3695 // cached references to old methods so it doesn't need to be
3696 // updated. We can simply start with the previous version(s) in
3697 // that case.
3698 ConstantPoolCache* cp_cache;
3699
3700 if (!ik->is_being_redefined()) {
3701 // this klass' constant pool cache may need adjustment
3702 ConstantPool* other_cp = ik->constants();
3703 cp_cache = other_cp->cache();
3704 if (cp_cache != NULL) {
3705 cp_cache->adjust_method_entries(&trace_name_printed);
3706 }
3707 }
3708
3709 // the previous versions' constant pool caches may need adjustment
3710 for (InstanceKlass* pv_node = ik->previous_versions();
3711 pv_node != NULL;
3712 pv_node = pv_node->previous_versions()) {
3713 cp_cache = pv_node->constants()->cache();
3714 if (cp_cache != NULL) {
3715 cp_cache->adjust_method_entries(&trace_name_printed);
3716 }
3717 }
3718 }
3719 }
3720
3721 void VM_RedefineClasses::update_jmethod_ids(Thread* thread) {
3722 for (int j = 0; j < _matching_methods_length; ++j) {
3723 Method* old_method = _matching_old_methods[j];
3724 jmethodID jmid = old_method->find_jmethod_id_or_null();
3725 if (jmid != NULL) {
3726 // There is a jmethodID, change it to point to the new method
3727 methodHandle new_method_h(thread, _matching_new_methods[j]);
3728 Method::change_method_associated_with_jmethod_id(jmid, new_method_h());
3729 assert(Method::resolve_jmethod_id(jmid) == _matching_new_methods[j],
3730 "should be replaced");
3731 }
3732 }
3733 }
3734
3735 int VM_RedefineClasses::check_methods_and_mark_as_obsolete() {
3736 int emcp_method_count = 0;
3737 int obsolete_count = 0;
3738 int old_index = 0;
3739 for (int j = 0; j < _matching_methods_length; ++j, ++old_index) {
3740 Method* old_method = _matching_old_methods[j];
3741 Method* new_method = _matching_new_methods[j];
3742 Method* old_array_method;
3743
3744 // Maintain an old_index into the _old_methods array by skipping
3745 // deleted methods
3746 while ((old_array_method = _old_methods->at(old_index)) != old_method) {
3747 ++old_index;
3748 }
3749
3750 if (MethodComparator::methods_EMCP(old_method, new_method)) {
3751 // The EMCP definition from JSR-163 requires the bytecodes to be
3752 // the same with the exception of constant pool indices which may
3753 // differ. However, the constants referred to by those indices
3754 // must be the same.
3755 //
3756 // We use methods_EMCP() for comparison since constant pool
3757 // merging can remove duplicate constant pool entries that were
3758 // present in the old method and removed from the rewritten new
3759 // method. A faster binary comparison function would consider the
3760 // old and new methods to be different when they are actually
3761 // EMCP.
3762 //
3763 // The old and new methods are EMCP and you would think that we
3764 // could get rid of one of them here and now and save some space.
3765 // However, the concept of EMCP only considers the bytecodes and
3766 // the constant pool entries in the comparison. Other things,
3767 // e.g., the line number table (LNT) or the local variable table
3768 // (LVT) don't count in the comparison. So the new (and EMCP)
3769 // method can have a new LNT that we need so we can't just
3770 // overwrite the new method with the old method.
3771 //
3772 // When this routine is called, we have already attached the new
3773 // methods to the_class so the old methods are effectively
3774 // overwritten. However, if an old method is still executing,
3775 // then the old method cannot be collected until sometime after
3776 // the old method call has returned. So the overwriting of old
3777 // methods by new methods will save us space except for those
3778 // (hopefully few) old methods that are still executing.
3779 //
3780 // A method refers to a ConstMethod* and this presents another
3781 // possible avenue to space savings. The ConstMethod* in the
3782 // new method contains possibly new attributes (LNT, LVT, etc).
3783 // At first glance, it seems possible to save space by replacing
3784 // the ConstMethod* in the old method with the ConstMethod*
3785 // from the new method. The old and new methods would share the
3786 // same ConstMethod* and we would save the space occupied by
3787 // the old ConstMethod*. However, the ConstMethod* contains
3788 // a back reference to the containing method. Sharing the
3789 // ConstMethod* between two methods could lead to confusion in
3790 // the code that uses the back reference. This would lead to
3791 // brittle code that could be broken in non-obvious ways now or
3792 // in the future.
3793 //
3794 // Another possibility is to copy the ConstMethod* from the new
3795 // method to the old method and then overwrite the new method with
3796 // the old method. Since the ConstMethod* contains the bytecodes
3797 // for the method embedded in the oop, this option would change
3798 // the bytecodes out from under any threads executing the old
3799 // method and make the thread's bcp invalid. Since EMCP requires
3800 // that the bytecodes be the same modulo constant pool indices, it
3801 // is straight forward to compute the correct new bcp in the new
3802 // ConstMethod* from the old bcp in the old ConstMethod*. The
3803 // time consuming part would be searching all the frames in all
3804 // of the threads to find all of the calls to the old method.
3805 //
3806 // It looks like we will have to live with the limited savings
3807 // that we get from effectively overwriting the old methods
3808 // when the new methods are attached to the_class.
3809
3810 // Count number of methods that are EMCP. The method will be marked
3811 // old but not obsolete if it is EMCP.
3812 emcp_method_count++;
3813
3814 // An EMCP method is _not_ obsolete. An obsolete method has a
3815 // different jmethodID than the current method. An EMCP method
3816 // has the same jmethodID as the current method. Having the
3817 // same jmethodID for all EMCP versions of a method allows for
3818 // a consistent view of the EMCP methods regardless of which
3819 // EMCP method you happen to have in hand. For example, a
3820 // breakpoint set in one EMCP method will work for all EMCP
3821 // versions of the method including the current one.
3822 } else {
3823 // mark obsolete methods as such
3824 old_method->set_is_obsolete();
3825 obsolete_count++;
3826
3827 // obsolete methods need a unique idnum so they become new entries in
3828 // the jmethodID cache in InstanceKlass
3829 assert(old_method->method_idnum() == new_method->method_idnum(), "must match");
3830 u2 num = InstanceKlass::cast(_the_class)->next_method_idnum();
3831 if (num != ConstMethod::UNSET_IDNUM) {
3832 old_method->set_method_idnum(num);
3833 }
3834
3835 // With tracing we try not to "yack" too much. The position of
3836 // this trace assumes there are fewer obsolete methods than
3837 // EMCP methods.
3838 if (log_is_enabled(Trace, redefine, class, obsolete, mark)) {
3839 ResourceMark rm;
3840 log_trace(redefine, class, obsolete, mark)
3841 ("mark %s(%s) as obsolete", old_method->name()->as_C_string(), old_method->signature()->as_C_string());
3842 }
3843 }
3844 old_method->set_is_old();
3845 }
3846 for (int i = 0; i < _deleted_methods_length; ++i) {
3847 Method* old_method = _deleted_methods[i];
3848
3849 assert(!old_method->has_vtable_index(),
3850 "cannot delete methods with vtable entries");;
3851
3852 // Mark all deleted methods as old, obsolete and deleted
3853 old_method->set_is_deleted();
3854 old_method->set_is_old();
3855 old_method->set_is_obsolete();
3856 ++obsolete_count;
3857 // With tracing we try not to "yack" too much. The position of
3858 // this trace assumes there are fewer obsolete methods than
3859 // EMCP methods.
3860 if (log_is_enabled(Trace, redefine, class, obsolete, mark)) {
3861 ResourceMark rm;
3862 log_trace(redefine, class, obsolete, mark)
3863 ("mark deleted %s(%s) as obsolete", old_method->name()->as_C_string(), old_method->signature()->as_C_string());
3864 }
3865 }
3866 assert((emcp_method_count + obsolete_count) == _old_methods->length(),
3867 "sanity check");
3868 log_trace(redefine, class, obsolete, mark)("EMCP_cnt=%d, obsolete_cnt=%d", emcp_method_count, obsolete_count);
3869 return emcp_method_count;
3870 }
3871
3872 // This internal class transfers the native function registration from old methods
3873 // to new methods. It is designed to handle both the simple case of unchanged
3874 // native methods and the complex cases of native method prefixes being added and/or
3875 // removed.
3876 // It expects only to be used during the VM_RedefineClasses op (a safepoint).
3877 //
3878 // This class is used after the new methods have been installed in "the_class".
3879 //
3880 // So, for example, the following must be handled. Where 'm' is a method and
3881 // a number followed by an underscore is a prefix.
3882 //
3883 // Old Name New Name
3884 // Simple transfer to new method m -> m
3885 // Add prefix m -> 1_m
3886 // Remove prefix 1_m -> m
3887 // Simultaneous add of prefixes m -> 3_2_1_m
3888 // Simultaneous removal of prefixes 3_2_1_m -> m
3889 // Simultaneous add and remove 1_m -> 2_m
3890 // Same, caused by prefix removal only 3_2_1_m -> 3_2_m
3891 //
3892 class TransferNativeFunctionRegistration {
3893 private:
3894 InstanceKlass* the_class;
3895 int prefix_count;
3896 char** prefixes;
3897
3898 // Recursively search the binary tree of possibly prefixed method names.
3899 // Iteration could be used if all agents were well behaved. Full tree walk is
3900 // more resilent to agents not cleaning up intermediate methods.
3901 // Branch at each depth in the binary tree is:
3902 // (1) without the prefix.
3903 // (2) with the prefix.
3904 // where 'prefix' is the prefix at that 'depth' (first prefix, second prefix,...)
3905 Method* search_prefix_name_space(int depth, char* name_str, size_t name_len,
3906 Symbol* signature) {
3907 TempNewSymbol name_symbol = SymbolTable::probe(name_str, (int)name_len);
3908 if (name_symbol != NULL) {
3909 Method* method = the_class->lookup_method(name_symbol, signature);
3910 if (method != NULL) {
3911 // Even if prefixed, intermediate methods must exist.
3912 if (method->is_native()) {
3913 // Wahoo, we found a (possibly prefixed) version of the method, return it.
3914 return method;
3915 }
3916 if (depth < prefix_count) {
3917 // Try applying further prefixes (other than this one).
3918 method = search_prefix_name_space(depth+1, name_str, name_len, signature);
3919 if (method != NULL) {
3920 return method; // found
3921 }
3922
3923 // Try adding this prefix to the method name and see if it matches
3924 // another method name.
3925 char* prefix = prefixes[depth];
3926 size_t prefix_len = strlen(prefix);
3927 size_t trial_len = name_len + prefix_len;
3928 char* trial_name_str = NEW_RESOURCE_ARRAY(char, trial_len + 1);
3929 strcpy(trial_name_str, prefix);
3930 strcat(trial_name_str, name_str);
3931 method = search_prefix_name_space(depth+1, trial_name_str, trial_len,
3932 signature);
3933 if (method != NULL) {
3934 // If found along this branch, it was prefixed, mark as such
3935 method->set_is_prefixed_native();
3936 return method; // found
3937 }
3938 }
3939 }
3940 }
3941 return NULL; // This whole branch bore nothing
3942 }
3943
3944 // Return the method name with old prefixes stripped away.
3945 char* method_name_without_prefixes(Method* method) {
3946 Symbol* name = method->name();
3947 char* name_str = name->as_utf8();
3948
3949 // Old prefixing may be defunct, strip prefixes, if any.
3950 for (int i = prefix_count-1; i >= 0; i--) {
3951 char* prefix = prefixes[i];
3952 size_t prefix_len = strlen(prefix);
3953 if (strncmp(prefix, name_str, prefix_len) == 0) {
3954 name_str += prefix_len;
3955 }
3956 }
3957 return name_str;
3958 }
3959
3960 // Strip any prefixes off the old native method, then try to find a
3961 // (possibly prefixed) new native that matches it.
3962 Method* strip_and_search_for_new_native(Method* method) {
3963 ResourceMark rm;
3964 char* name_str = method_name_without_prefixes(method);
3965 return search_prefix_name_space(0, name_str, strlen(name_str),
3966 method->signature());
3967 }
3968
3969 public:
3970
3971 // Construct a native method transfer processor for this class.
3972 TransferNativeFunctionRegistration(InstanceKlass* _the_class) {
3973 assert(SafepointSynchronize::is_at_safepoint(), "sanity check");
3974
3975 the_class = _the_class;
3976 prefixes = JvmtiExport::get_all_native_method_prefixes(&prefix_count);
3977 }
3978
3979 // Attempt to transfer any of the old or deleted methods that are native
3980 void transfer_registrations(Method** old_methods, int methods_length) {
3981 for (int j = 0; j < methods_length; j++) {
3982 Method* old_method = old_methods[j];
3983
3984 if (old_method->is_native() && old_method->has_native_function()) {
3985 Method* new_method = strip_and_search_for_new_native(old_method);
3986 if (new_method != NULL) {
3987 // Actually set the native function in the new method.
3988 // Redefine does not send events (except CFLH), certainly not this
3989 // behind the scenes re-registration.
3990 new_method->set_native_function(old_method->native_function(),
3991 !Method::native_bind_event_is_interesting);
3992 }
3993 }
3994 }
3995 }
3996 };
3997
3998 // Don't lose the association between a native method and its JNI function.
3999 void VM_RedefineClasses::transfer_old_native_function_registrations(InstanceKlass* the_class) {
4000 TransferNativeFunctionRegistration transfer(the_class);
4001 transfer.transfer_registrations(_deleted_methods, _deleted_methods_length);
4002 transfer.transfer_registrations(_matching_old_methods, _matching_methods_length);
4003 }
4004
4005 // Deoptimize all compiled code that depends on this class.
4006 //
4007 // If the can_redefine_classes capability is obtained in the onload
4008 // phase then the compiler has recorded all dependencies from startup.
4009 // In that case we need only deoptimize and throw away all compiled code
4010 // that depends on the class.
4011 //
4012 // If can_redefine_classes is obtained sometime after the onload
4013 // phase then the dependency information may be incomplete. In that case
4014 // the first call to RedefineClasses causes all compiled code to be
4015 // thrown away. As can_redefine_classes has been obtained then
4016 // all future compilations will record dependencies so second and
4017 // subsequent calls to RedefineClasses need only throw away code
4018 // that depends on the class.
4019 //
4020
4021 // First step is to walk the code cache for each class redefined and mark
4022 // dependent methods. Wait until all classes are processed to deoptimize everything.
4023 void VM_RedefineClasses::mark_dependent_code(InstanceKlass* ik) {
4024 assert_locked_or_safepoint(Compile_lock);
4025
4026 // All dependencies have been recorded from startup or this is a second or
4027 // subsequent use of RedefineClasses
4028 if (JvmtiExport::all_dependencies_are_recorded()) {
4029 CodeCache::mark_for_evol_deoptimization(ik);
4030 }
4031 }
4032
4033 void VM_RedefineClasses::flush_dependent_code() {
4034 assert(SafepointSynchronize::is_at_safepoint(), "sanity check");
4035
4036 bool deopt_needed;
4037
4038 // This is the first redefinition, mark all the nmethods for deoptimization
4039 if (!JvmtiExport::all_dependencies_are_recorded()) {
4040 log_debug(redefine, class, nmethod)("Marked all nmethods for deopt");
4041 CodeCache::mark_all_nmethods_for_evol_deoptimization();
4042 deopt_needed = true;
4043 } else {
4044 int deopt = CodeCache::mark_dependents_for_evol_deoptimization();
4045 log_debug(redefine, class, nmethod)("Marked %d dependent nmethods for deopt", deopt);
4046 deopt_needed = (deopt != 0);
4047 }
4048
4049 if (deopt_needed) {
4050 CodeCache::flush_evol_dependents();
4051 }
4052
4053 // From now on we know that the dependency information is complete
4054 JvmtiExport::set_all_dependencies_are_recorded(true);
4055 }
4056
4057 void VM_RedefineClasses::compute_added_deleted_matching_methods() {
4058 Method* old_method;
4059 Method* new_method;
4060
4061 _matching_old_methods = NEW_RESOURCE_ARRAY(Method*, _old_methods->length());
4062 _matching_new_methods = NEW_RESOURCE_ARRAY(Method*, _old_methods->length());
4063 _added_methods = NEW_RESOURCE_ARRAY(Method*, _new_methods->length());
4064 _deleted_methods = NEW_RESOURCE_ARRAY(Method*, _old_methods->length());
4065
4066 _matching_methods_length = 0;
4067 _deleted_methods_length = 0;
4068 _added_methods_length = 0;
4069
4070 int nj = 0;
4071 int oj = 0;
4072 while (true) {
4073 if (oj >= _old_methods->length()) {
4074 if (nj >= _new_methods->length()) {
4075 break; // we've looked at everything, done
4076 }
4077 // New method at the end
4078 new_method = _new_methods->at(nj);
4079 _added_methods[_added_methods_length++] = new_method;
4080 ++nj;
4081 } else if (nj >= _new_methods->length()) {
4082 // Old method, at the end, is deleted
4083 old_method = _old_methods->at(oj);
4084 _deleted_methods[_deleted_methods_length++] = old_method;
4085 ++oj;
4086 } else {
4087 old_method = _old_methods->at(oj);
4088 new_method = _new_methods->at(nj);
4089 if (old_method->name() == new_method->name()) {
4090 if (old_method->signature() == new_method->signature()) {
4091 _matching_old_methods[_matching_methods_length ] = old_method;
4092 _matching_new_methods[_matching_methods_length++] = new_method;
4093 ++nj;
4094 ++oj;
4095 } else {
4096 // added overloaded have already been moved to the end,
4097 // so this is a deleted overloaded method
4098 _deleted_methods[_deleted_methods_length++] = old_method;
4099 ++oj;
4100 }
4101 } else { // names don't match
4102 if (old_method->name()->fast_compare(new_method->name()) > 0) {
4103 // new method
4104 _added_methods[_added_methods_length++] = new_method;
4105 ++nj;
4106 } else {
4107 // deleted method
4108 _deleted_methods[_deleted_methods_length++] = old_method;
4109 ++oj;
4110 }
4111 }
4112 }
4113 }
4114 assert(_matching_methods_length + _deleted_methods_length == _old_methods->length(), "sanity");
4115 assert(_matching_methods_length + _added_methods_length == _new_methods->length(), "sanity");
4116 }
4117
4118
4119 void VM_RedefineClasses::swap_annotations(InstanceKlass* the_class,
4120 InstanceKlass* scratch_class) {
4121 // Swap annotation fields values
4122 Annotations* old_annotations = the_class->annotations();
4123 the_class->set_annotations(scratch_class->annotations());
4124 scratch_class->set_annotations(old_annotations);
4125 }
4126
4127
4128 // Install the redefinition of a class:
4129 // - house keeping (flushing breakpoints and caches, deoptimizing
4130 // dependent compiled code)
4131 // - replacing parts in the_class with parts from scratch_class
4132 // - adding a weak reference to track the obsolete but interesting
4133 // parts of the_class
4134 // - adjusting constant pool caches and vtables in other classes
4135 // that refer to methods in the_class. These adjustments use the
4136 // ClassLoaderDataGraph::classes_do() facility which only allows
4137 // a helper method to be specified. The interesting parameters
4138 // that we would like to pass to the helper method are saved in
4139 // static global fields in the VM operation.
4140 void VM_RedefineClasses::redefine_single_class(jclass the_jclass,
4141 InstanceKlass* scratch_class, TRAPS) {
4142
4143 HandleMark hm(THREAD); // make sure handles from this call are freed
4144
4145 if (log_is_enabled(Info, redefine, class, timer)) {
4146 _timer_rsc_phase1.start();
4147 }
4148
4149 InstanceKlass* the_class = get_ik(the_jclass);
4150
4151 // Set some flags to control and optimize adjusting method entries
4152 _has_redefined_Object |= the_class == SystemDictionary::Object_klass();
4153 _has_null_class_loader |= the_class->class_loader() == NULL;
4154
4155 // Remove all breakpoints in methods of this class
4156 JvmtiBreakpoints& jvmti_breakpoints = JvmtiCurrentBreakpoints::get_jvmti_breakpoints();
4157 jvmti_breakpoints.clearall_in_class_at_safepoint(the_class);
4158
4159 // Mark all compiled code that depends on this class
4160 mark_dependent_code(the_class);
4161
4162 _old_methods = the_class->methods();
4163 _new_methods = scratch_class->methods();
4164 _the_class = the_class;
4165 compute_added_deleted_matching_methods();
4166 update_jmethod_ids(THREAD);
4167
4168 _any_class_has_resolved_methods = the_class->has_resolved_methods() || _any_class_has_resolved_methods;
4169
4170 // Attach new constant pool to the original klass. The original
4171 // klass still refers to the old constant pool (for now).
4172 scratch_class->constants()->set_pool_holder(the_class);
4173
4174 #if 0
4175 // In theory, with constant pool merging in place we should be able
4176 // to save space by using the new, merged constant pool in place of
4177 // the old constant pool(s). By "pool(s)" I mean the constant pool in
4178 // the klass version we are replacing now and any constant pool(s) in
4179 // previous versions of klass. Nice theory, doesn't work in practice.
4180 // When this code is enabled, even simple programs throw NullPointer
4181 // exceptions. I'm guessing that this is caused by some constant pool
4182 // cache difference between the new, merged constant pool and the
4183 // constant pool that was just being used by the klass. I'm keeping
4184 // this code around to archive the idea, but the code has to remain
4185 // disabled for now.
4186
4187 // Attach each old method to the new constant pool. This can be
4188 // done here since we are past the bytecode verification and
4189 // constant pool optimization phases.
4190 for (int i = _old_methods->length() - 1; i >= 0; i--) {
4191 Method* method = _old_methods->at(i);
4192 method->set_constants(scratch_class->constants());
4193 }
4194
4195 // NOTE: this doesn't work because you can redefine the same class in two
4196 // threads, each getting their own constant pool data appended to the
4197 // original constant pool. In order for the new methods to work when they
4198 // become old methods, they need to keep their updated copy of the constant pool.
4199
4200 {
4201 // walk all previous versions of the klass
4202 InstanceKlass *ik = the_class;
4203 PreviousVersionWalker pvw(ik);
4204 do {
4205 ik = pvw.next_previous_version();
4206 if (ik != NULL) {
4207
4208 // attach previous version of klass to the new constant pool
4209 ik->set_constants(scratch_class->constants());
4210
4211 // Attach each method in the previous version of klass to the
4212 // new constant pool
4213 Array<Method*>* prev_methods = ik->methods();
4214 for (int i = prev_methods->length() - 1; i >= 0; i--) {
4215 Method* method = prev_methods->at(i);
4216 method->set_constants(scratch_class->constants());
4217 }
4218 }
4219 } while (ik != NULL);
4220 }
4221 #endif
4222
4223 // Replace methods and constantpool
4224 the_class->set_methods(_new_methods);
4225 scratch_class->set_methods(_old_methods); // To prevent potential GCing of the old methods,
4226 // and to be able to undo operation easily.
4227
4228 Array<int>* old_ordering = the_class->method_ordering();
4229 the_class->set_method_ordering(scratch_class->method_ordering());
4230 scratch_class->set_method_ordering(old_ordering);
4231
4232 ConstantPool* old_constants = the_class->constants();
4233 the_class->set_constants(scratch_class->constants());
4234 scratch_class->set_constants(old_constants); // See the previous comment.
4235 #if 0
4236 // We are swapping the guts of "the new class" with the guts of "the
4237 // class". Since the old constant pool has just been attached to "the
4238 // new class", it seems logical to set the pool holder in the old
4239 // constant pool also. However, doing this will change the observable
4240 // class hierarchy for any old methods that are still executing. A
4241 // method can query the identity of its "holder" and this query uses
4242 // the method's constant pool link to find the holder. The change in
4243 // holding class from "the class" to "the new class" can confuse
4244 // things.
4245 //
4246 // Setting the old constant pool's holder will also cause
4247 // verification done during vtable initialization below to fail.
4248 // During vtable initialization, the vtable's class is verified to be
4249 // a subtype of the method's holder. The vtable's class is "the
4250 // class" and the method's holder is gotten from the constant pool
4251 // link in the method itself. For "the class"'s directly implemented
4252 // methods, the method holder is "the class" itself (as gotten from
4253 // the new constant pool). The check works fine in this case. The
4254 // check also works fine for methods inherited from super classes.
4255 //
4256 // Miranda methods are a little more complicated. A miranda method is
4257 // provided by an interface when the class implementing the interface
4258 // does not provide its own method. These interfaces are implemented
4259 // internally as an InstanceKlass. These special instanceKlasses
4260 // share the constant pool of the class that "implements" the
4261 // interface. By sharing the constant pool, the method holder of a
4262 // miranda method is the class that "implements" the interface. In a
4263 // non-redefine situation, the subtype check works fine. However, if
4264 // the old constant pool's pool holder is modified, then the check
4265 // fails because there is no class hierarchy relationship between the
4266 // vtable's class and "the new class".
4267
4268 old_constants->set_pool_holder(scratch_class());
4269 #endif
4270
4271 // track number of methods that are EMCP for add_previous_version() call below
4272 int emcp_method_count = check_methods_and_mark_as_obsolete();
4273 transfer_old_native_function_registrations(the_class);
4274
4275 // The class file bytes from before any retransformable agents mucked
4276 // with them was cached on the scratch class, move to the_class.
4277 // Note: we still want to do this if nothing needed caching since it
4278 // should get cleared in the_class too.
4279 if (the_class->get_cached_class_file() == 0) {
4280 // the_class doesn't have a cache yet so copy it
4281 the_class->set_cached_class_file(scratch_class->get_cached_class_file());
4282 }
4283 else if (scratch_class->get_cached_class_file() !=
4284 the_class->get_cached_class_file()) {
4285 // The same class can be present twice in the scratch classes list or there
4286 // are multiple concurrent RetransformClasses calls on different threads.
4287 // In such cases we have to deallocate scratch_class cached_class_file.
4288 os::free(scratch_class->get_cached_class_file());
4289 }
4290
4291 // NULL out in scratch class to not delete twice. The class to be redefined
4292 // always owns these bytes.
4293 scratch_class->set_cached_class_file(NULL);
4294
4295 // Replace inner_classes
4296 Array<u2>* old_inner_classes = the_class->inner_classes();
4297 the_class->set_inner_classes(scratch_class->inner_classes());
4298 scratch_class->set_inner_classes(old_inner_classes);
4299
4300 // Initialize the vtable and interface table after
4301 // methods have been rewritten
4302 // no exception should happen here since we explicitly
4303 // do not check loader constraints.
4304 // compare_and_normalize_class_versions has already checked:
4305 // - classloaders unchanged, signatures unchanged
4306 // - all instanceKlasses for redefined classes reused & contents updated
4307 the_class->vtable().initialize_vtable(false, THREAD);
4308 the_class->itable().initialize_itable(false, THREAD);
4309 assert(!HAS_PENDING_EXCEPTION || (THREAD->pending_exception()->is_a(SystemDictionary::ThreadDeath_klass())), "redefine exception");
4310
4311 // Leave arrays of jmethodIDs and itable index cache unchanged
4312
4313 // Copy the "source file name" attribute from new class version
4314 the_class->set_source_file_name_index(
4315 scratch_class->source_file_name_index());
4316
4317 // Copy the "source debug extension" attribute from new class version
4318 the_class->set_source_debug_extension(
4319 scratch_class->source_debug_extension(),
4320 scratch_class->source_debug_extension() == NULL ? 0 :
4321 (int)strlen(scratch_class->source_debug_extension()));
4322
4323 // Use of javac -g could be different in the old and the new
4324 if (scratch_class->access_flags().has_localvariable_table() !=
4325 the_class->access_flags().has_localvariable_table()) {
4326
4327 AccessFlags flags = the_class->access_flags();
4328 if (scratch_class->access_flags().has_localvariable_table()) {
4329 flags.set_has_localvariable_table();
4330 } else {
4331 flags.clear_has_localvariable_table();
4332 }
4333 the_class->set_access_flags(flags);
4334 }
4335
4336 swap_annotations(the_class, scratch_class);
4337
4338 // Replace CP indexes for class and name+type of enclosing method
4339 u2 old_class_idx = the_class->enclosing_method_class_index();
4340 u2 old_method_idx = the_class->enclosing_method_method_index();
4341 the_class->set_enclosing_method_indices(
4342 scratch_class->enclosing_method_class_index(),
4343 scratch_class->enclosing_method_method_index());
4344 scratch_class->set_enclosing_method_indices(old_class_idx, old_method_idx);
4345
4346 // Replace fingerprint data
4347 the_class->set_has_passed_fingerprint_check(scratch_class->has_passed_fingerprint_check());
4348 the_class->store_fingerprint(scratch_class->get_stored_fingerprint());
4349
4350 the_class->set_has_been_redefined();
4351
4352 if (!the_class->should_be_initialized()) {
4353 // Class was already initialized, so AOT has only seen the original version.
4354 // We need to let AOT look at it again.
4355 AOTLoader::load_for_klass(the_class, THREAD);
4356 }
4357
4358 // keep track of previous versions of this class
4359 the_class->add_previous_version(scratch_class, emcp_method_count);
4360
4361 _timer_rsc_phase1.stop();
4362 if (log_is_enabled(Info, redefine, class, timer)) {
4363 _timer_rsc_phase2.start();
4364 }
4365
4366 if (the_class->oop_map_cache() != NULL) {
4367 // Flush references to any obsolete methods from the oop map cache
4368 // so that obsolete methods are not pinned.
4369 the_class->oop_map_cache()->flush_obsolete_entries();
4370 }
4371
4372 increment_class_counter((InstanceKlass *)the_class, THREAD);
4373
4374 if (EventClassRedefinition::is_enabled()) {
4375 EventClassRedefinition event;
4376 event.set_classModificationCount(java_lang_Class::classRedefinedCount(the_class->java_mirror()));
4377 event.set_redefinedClass(the_class);
4378 event.set_redefinitionId(_id);
4379 event.commit();
4380 }
4381
4382 {
4383 ResourceMark rm(THREAD);
4384 // increment the classRedefinedCount field in the_class and in any
4385 // direct and indirect subclasses of the_class
4386 log_info(redefine, class, load)
4387 ("redefined name=%s, count=%d (avail_mem=" UINT64_FORMAT "K)",
4388 the_class->external_name(), java_lang_Class::classRedefinedCount(the_class->java_mirror()), os::available_memory() >> 10);
4389 Events::log_redefinition(THREAD, "redefined class name=%s, count=%d",
4390 the_class->external_name(),
4391 java_lang_Class::classRedefinedCount(the_class->java_mirror()));
4392
4393 }
4394 _timer_rsc_phase2.stop();
4395
4396 } // end redefine_single_class()
4397
4398
4399 // Increment the classRedefinedCount field in the specific InstanceKlass
4400 // and in all direct and indirect subclasses.
4401 void VM_RedefineClasses::increment_class_counter(InstanceKlass *ik, TRAPS) {
4402 oop class_mirror = ik->java_mirror();
4403 Klass* class_oop = java_lang_Class::as_Klass(class_mirror);
4404 int new_count = java_lang_Class::classRedefinedCount(class_mirror) + 1;
4405 java_lang_Class::set_classRedefinedCount(class_mirror, new_count);
4406
4407 if (class_oop != _the_class) {
4408 // _the_class count is printed at end of redefine_single_class()
4409 log_debug(redefine, class, subclass)("updated count in subclass=%s to %d", ik->external_name(), new_count);
4410 }
4411
4412 for (Klass *subk = ik->subklass(); subk != NULL;
4413 subk = subk->next_sibling()) {
4414 if (subk->is_instance_klass()) {
4415 // Only update instanceKlasses
4416 InstanceKlass *subik = InstanceKlass::cast(subk);
4417 // recursively do subclasses of the current subclass
4418 increment_class_counter(subik, THREAD);
4419 }
4420 }
4421 }
4422
4423 void VM_RedefineClasses::CheckClass::do_klass(Klass* k) {
4424 bool no_old_methods = true; // be optimistic
4425
4426 // Both array and instance classes have vtables.
4427 // a vtable should never contain old or obsolete methods
4428 ResourceMark rm(_thread);
4429 if (k->vtable_length() > 0 &&
4430 !k->vtable().check_no_old_or_obsolete_entries()) {
4431 if (log_is_enabled(Trace, redefine, class, obsolete, metadata)) {
4432 log_trace(redefine, class, obsolete, metadata)
4433 ("klassVtable::check_no_old_or_obsolete_entries failure -- OLD or OBSOLETE method found -- class: %s",
4434 k->signature_name());
4435 k->vtable().dump_vtable();
4436 }
4437 no_old_methods = false;
4438 }
4439
4440 if (k->is_instance_klass()) {
4441 HandleMark hm(_thread);
4442 InstanceKlass *ik = InstanceKlass::cast(k);
4443
4444 // an itable should never contain old or obsolete methods
4445 if (ik->itable_length() > 0 &&
4446 !ik->itable().check_no_old_or_obsolete_entries()) {
4447 if (log_is_enabled(Trace, redefine, class, obsolete, metadata)) {
4448 log_trace(redefine, class, obsolete, metadata)
4449 ("klassItable::check_no_old_or_obsolete_entries failure -- OLD or OBSOLETE method found -- class: %s",
4450 ik->signature_name());
4451 ik->itable().dump_itable();
4452 }
4453 no_old_methods = false;
4454 }
4455
4456 // the constant pool cache should never contain non-deleted old or obsolete methods
4457 if (ik->constants() != NULL &&
4458 ik->constants()->cache() != NULL &&
4459 !ik->constants()->cache()->check_no_old_or_obsolete_entries()) {
4460 if (log_is_enabled(Trace, redefine, class, obsolete, metadata)) {
4461 log_trace(redefine, class, obsolete, metadata)
4462 ("cp-cache::check_no_old_or_obsolete_entries failure -- OLD or OBSOLETE method found -- class: %s",
4463 ik->signature_name());
4464 ik->constants()->cache()->dump_cache();
4465 }
4466 no_old_methods = false;
4467 }
4468 }
4469
4470 // print and fail guarantee if old methods are found.
4471 if (!no_old_methods) {
4472 if (log_is_enabled(Trace, redefine, class, obsolete, metadata)) {
4473 dump_methods();
4474 } else {
4475 log_trace(redefine, class)("Use the '-Xlog:redefine+class*:' option "
4476 "to see more info about the following guarantee() failure.");
4477 }
4478 guarantee(false, "OLD and/or OBSOLETE method(s) found");
4479 }
4480 }
4481
4482 u8 VM_RedefineClasses::next_id() {
4483 while (true) {
4484 u8 id = _id_counter;
4485 u8 next_id = id + 1;
4486 u8 result = Atomic::cmpxchg(&_id_counter, id, next_id);
4487 if (result == id) {
4488 return next_id;
4489 }
4490 }
4491 }
4492
4493 void VM_RedefineClasses::dump_methods() {
4494 int j;
4495 log_trace(redefine, class, dump)("_old_methods --");
4496 for (j = 0; j < _old_methods->length(); ++j) {
4497 LogStreamHandle(Trace, redefine, class, dump) log_stream;
4498 Method* m = _old_methods->at(j);
4499 log_stream.print("%4d (%5d) ", j, m->vtable_index());
4500 m->access_flags().print_on(&log_stream);
4501 log_stream.print(" -- ");
4502 m->print_name(&log_stream);
4503 log_stream.cr();
4504 }
4505 log_trace(redefine, class, dump)("_new_methods --");
4506 for (j = 0; j < _new_methods->length(); ++j) {
4507 LogStreamHandle(Trace, redefine, class, dump) log_stream;
4508 Method* m = _new_methods->at(j);
4509 log_stream.print("%4d (%5d) ", j, m->vtable_index());
4510 m->access_flags().print_on(&log_stream);
4511 log_stream.print(" -- ");
4512 m->print_name(&log_stream);
4513 log_stream.cr();
4514 }
4515 log_trace(redefine, class, dump)("_matching_methods --");
4516 for (j = 0; j < _matching_methods_length; ++j) {
4517 LogStreamHandle(Trace, redefine, class, dump) log_stream;
4518 Method* m = _matching_old_methods[j];
4519 log_stream.print("%4d (%5d) ", j, m->vtable_index());
4520 m->access_flags().print_on(&log_stream);
4521 log_stream.print(" -- ");
4522 m->print_name();
4523 log_stream.cr();
4524
4525 m = _matching_new_methods[j];
4526 log_stream.print(" (%5d) ", m->vtable_index());
4527 m->access_flags().print_on(&log_stream);
4528 log_stream.cr();
4529 }
4530 log_trace(redefine, class, dump)("_deleted_methods --");
4531 for (j = 0; j < _deleted_methods_length; ++j) {
4532 LogStreamHandle(Trace, redefine, class, dump) log_stream;
4533 Method* m = _deleted_methods[j];
4534 log_stream.print("%4d (%5d) ", j, m->vtable_index());
4535 m->access_flags().print_on(&log_stream);
4536 log_stream.print(" -- ");
4537 m->print_name(&log_stream);
4538 log_stream.cr();
4539 }
4540 log_trace(redefine, class, dump)("_added_methods --");
4541 for (j = 0; j < _added_methods_length; ++j) {
4542 LogStreamHandle(Trace, redefine, class, dump) log_stream;
4543 Method* m = _added_methods[j];
4544 log_stream.print("%4d (%5d) ", j, m->vtable_index());
4545 m->access_flags().print_on(&log_stream);
4546 log_stream.print(" -- ");
4547 m->print_name(&log_stream);
4548 log_stream.cr();
4549 }
4550 }
4551
4552 void VM_RedefineClasses::print_on_error(outputStream* st) const {
4553 VM_Operation::print_on_error(st);
4554 if (_the_class != NULL) {
4555 ResourceMark rm;
4556 st->print_cr(", redefining class %s", _the_class->external_name());
4557 }
4558 }