Mon, 12 Nov 2012 16:15:05 -0500
8001471: Klass::cast() does nothing
Summary: Remove function Klass::cast() and calls to it.
Reviewed-by: dholmes, coleenp
1 /*
2 * Copyright (c) 2003, 2012, 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 */
25 #include "precompiled.hpp"
26 #include "classfile/systemDictionary.hpp"
27 #include "classfile/verifier.hpp"
28 #include "code/codeCache.hpp"
29 #include "compiler/compileBroker.hpp"
30 #include "interpreter/oopMapCache.hpp"
31 #include "interpreter/rewriter.hpp"
32 #include "memory/gcLocker.hpp"
33 #include "memory/metadataFactory.hpp"
34 #include "memory/metaspaceShared.hpp"
35 #include "memory/universe.inline.hpp"
36 #include "oops/fieldStreams.hpp"
37 #include "oops/klassVtable.hpp"
38 #include "prims/jvmtiImpl.hpp"
39 #include "prims/jvmtiRedefineClasses.hpp"
40 #include "prims/methodComparator.hpp"
41 #include "runtime/deoptimization.hpp"
42 #include "runtime/relocator.hpp"
43 #include "utilities/bitMap.inline.hpp"
46 Array<Method*>* VM_RedefineClasses::_old_methods = NULL;
47 Array<Method*>* VM_RedefineClasses::_new_methods = NULL;
48 Method** VM_RedefineClasses::_matching_old_methods = NULL;
49 Method** VM_RedefineClasses::_matching_new_methods = NULL;
50 Method** VM_RedefineClasses::_deleted_methods = NULL;
51 Method** VM_RedefineClasses::_added_methods = NULL;
52 int VM_RedefineClasses::_matching_methods_length = 0;
53 int VM_RedefineClasses::_deleted_methods_length = 0;
54 int VM_RedefineClasses::_added_methods_length = 0;
55 Klass* VM_RedefineClasses::_the_class_oop = NULL;
58 VM_RedefineClasses::VM_RedefineClasses(jint class_count,
59 const jvmtiClassDefinition *class_defs,
60 JvmtiClassLoadKind class_load_kind) {
61 _class_count = class_count;
62 _class_defs = class_defs;
63 _class_load_kind = class_load_kind;
64 _res = JVMTI_ERROR_NONE;
65 }
67 bool VM_RedefineClasses::doit_prologue() {
68 if (_class_count == 0) {
69 _res = JVMTI_ERROR_NONE;
70 return false;
71 }
72 if (_class_defs == NULL) {
73 _res = JVMTI_ERROR_NULL_POINTER;
74 return false;
75 }
76 for (int i = 0; i < _class_count; i++) {
77 if (_class_defs[i].klass == NULL) {
78 _res = JVMTI_ERROR_INVALID_CLASS;
79 return false;
80 }
81 if (_class_defs[i].class_byte_count == 0) {
82 _res = JVMTI_ERROR_INVALID_CLASS_FORMAT;
83 return false;
84 }
85 if (_class_defs[i].class_bytes == NULL) {
86 _res = JVMTI_ERROR_NULL_POINTER;
87 return false;
88 }
89 }
91 // Start timer after all the sanity checks; not quite accurate, but
92 // better than adding a bunch of stop() calls.
93 RC_TIMER_START(_timer_vm_op_prologue);
95 // We first load new class versions in the prologue, because somewhere down the
96 // call chain it is required that the current thread is a Java thread.
97 _res = load_new_class_versions(Thread::current());
98 if (_res != JVMTI_ERROR_NONE) {
99 // free any successfully created classes, since none are redefined
100 for (int i = 0; i < _class_count; i++) {
101 if (_scratch_classes[i] != NULL) {
102 ClassLoaderData* cld = _scratch_classes[i]->class_loader_data();
103 // Free the memory for this class at class unloading time. Not before
104 // because CMS might think this is still live.
105 cld->add_to_deallocate_list((InstanceKlass*)_scratch_classes[i]);
106 }
107 }
108 // Free os::malloc allocated memory in load_new_class_version.
109 os::free(_scratch_classes);
110 RC_TIMER_STOP(_timer_vm_op_prologue);
111 return false;
112 }
114 RC_TIMER_STOP(_timer_vm_op_prologue);
115 return true;
116 }
118 // Keep track of marked on-stack metadata so it can be cleared.
119 GrowableArray<Metadata*>* _marked_objects = NULL;
120 NOT_PRODUCT(bool MetadataOnStackMark::_is_active = false;)
122 // Walk metadata on the stack and mark it so that redefinition doesn't delete
123 // it. Class unloading also walks the previous versions and might try to
124 // delete it, so this class is used by class unloading also.
125 MetadataOnStackMark::MetadataOnStackMark() {
126 assert(SafepointSynchronize::is_at_safepoint(), "sanity check");
127 NOT_PRODUCT(_is_active = true;)
128 if (_marked_objects == NULL) {
129 _marked_objects = new (ResourceObj::C_HEAP, mtClass) GrowableArray<Metadata*>(1000, true);
130 }
131 Threads::metadata_do(Metadata::mark_on_stack);
132 CodeCache::alive_nmethods_do(nmethod::mark_on_stack);
133 CompileBroker::mark_on_stack();
134 }
136 MetadataOnStackMark::~MetadataOnStackMark() {
137 assert(SafepointSynchronize::is_at_safepoint(), "sanity check");
138 // Unmark everything that was marked. Can't do the same walk because
139 // redefine classes messes up the code cache so the set of methods
140 // might not be the same.
141 for (int i = 0; i< _marked_objects->length(); i++) {
142 _marked_objects->at(i)->set_on_stack(false);
143 }
144 _marked_objects->clear(); // reuse growable array for next time.
145 NOT_PRODUCT(_is_active = false;)
146 }
148 // Record which objects are marked so we can unmark the same objects.
149 void MetadataOnStackMark::record(Metadata* m) {
150 assert(_is_active, "metadata on stack marking is active");
151 _marked_objects->push(m);
152 }
155 void VM_RedefineClasses::doit() {
156 Thread *thread = Thread::current();
158 if (UseSharedSpaces) {
159 // Sharing is enabled so we remap the shared readonly space to
160 // shared readwrite, private just in case we need to redefine
161 // a shared class. We do the remap during the doit() phase of
162 // the safepoint to be safer.
163 if (!MetaspaceShared::remap_shared_readonly_as_readwrite()) {
164 RC_TRACE_WITH_THREAD(0x00000001, thread,
165 ("failed to remap shared readonly space to readwrite, private"));
166 _res = JVMTI_ERROR_INTERNAL;
167 return;
168 }
169 }
171 // Mark methods seen on stack and everywhere else so old methods are not
172 // cleaned up if they're on the stack.
173 MetadataOnStackMark md_on_stack;
174 HandleMark hm(thread); // make sure any handles created are deleted
175 // before the stack walk again.
177 for (int i = 0; i < _class_count; i++) {
178 redefine_single_class(_class_defs[i].klass, _scratch_classes[i], thread);
179 ClassLoaderData* cld = _scratch_classes[i]->class_loader_data();
180 // Free the memory for this class at class unloading time. Not before
181 // because CMS might think this is still live.
182 cld->add_to_deallocate_list((InstanceKlass*)_scratch_classes[i]);
183 _scratch_classes[i] = NULL;
184 }
186 // Disable any dependent concurrent compilations
187 SystemDictionary::notice_modification();
189 // Set flag indicating that some invariants are no longer true.
190 // See jvmtiExport.hpp for detailed explanation.
191 JvmtiExport::set_has_redefined_a_class();
193 #ifdef ASSERT
194 SystemDictionary::classes_do(check_class, thread);
195 #endif
196 }
198 void VM_RedefineClasses::doit_epilogue() {
199 // Free os::malloc allocated memory.
200 os::free(_scratch_classes);
202 if (RC_TRACE_ENABLED(0x00000004)) {
203 // Used to have separate timers for "doit" and "all", but the timer
204 // overhead skewed the measurements.
205 jlong doit_time = _timer_rsc_phase1.milliseconds() +
206 _timer_rsc_phase2.milliseconds();
207 jlong all_time = _timer_vm_op_prologue.milliseconds() + doit_time;
209 RC_TRACE(0x00000004, ("vm_op: all=" UINT64_FORMAT
210 " prologue=" UINT64_FORMAT " doit=" UINT64_FORMAT, all_time,
211 _timer_vm_op_prologue.milliseconds(), doit_time));
212 RC_TRACE(0x00000004,
213 ("redefine_single_class: phase1=" UINT64_FORMAT " phase2=" UINT64_FORMAT,
214 _timer_rsc_phase1.milliseconds(), _timer_rsc_phase2.milliseconds()));
215 }
216 }
218 bool VM_RedefineClasses::is_modifiable_class(oop klass_mirror) {
219 // classes for primitives cannot be redefined
220 if (java_lang_Class::is_primitive(klass_mirror)) {
221 return false;
222 }
223 Klass* the_class_oop = java_lang_Class::as_Klass(klass_mirror);
224 // classes for arrays cannot be redefined
225 if (the_class_oop == NULL || !the_class_oop->oop_is_instance()) {
226 return false;
227 }
228 return true;
229 }
231 // Append the current entry at scratch_i in scratch_cp to *merge_cp_p
232 // where the end of *merge_cp_p is specified by *merge_cp_length_p. For
233 // direct CP entries, there is just the current entry to append. For
234 // indirect and double-indirect CP entries, there are zero or more
235 // referenced CP entries along with the current entry to append.
236 // Indirect and double-indirect CP entries are handled by recursive
237 // calls to append_entry() as needed. The referenced CP entries are
238 // always appended to *merge_cp_p before the referee CP entry. These
239 // referenced CP entries may already exist in *merge_cp_p in which case
240 // there is nothing extra to append and only the current entry is
241 // appended.
242 void VM_RedefineClasses::append_entry(constantPoolHandle scratch_cp,
243 int scratch_i, constantPoolHandle *merge_cp_p, int *merge_cp_length_p,
244 TRAPS) {
246 // append is different depending on entry tag type
247 switch (scratch_cp->tag_at(scratch_i).value()) {
249 // The old verifier is implemented outside the VM. It loads classes,
250 // but does not resolve constant pool entries directly so we never
251 // see Class entries here with the old verifier. Similarly the old
252 // verifier does not like Class entries in the input constant pool.
253 // The split-verifier is implemented in the VM so it can optionally
254 // and directly resolve constant pool entries to load classes. The
255 // split-verifier can accept either Class entries or UnresolvedClass
256 // entries in the input constant pool. We revert the appended copy
257 // back to UnresolvedClass so that either verifier will be happy
258 // with the constant pool entry.
259 case JVM_CONSTANT_Class:
260 {
261 // revert the copy to JVM_CONSTANT_UnresolvedClass
262 (*merge_cp_p)->unresolved_klass_at_put(*merge_cp_length_p,
263 scratch_cp->klass_name_at(scratch_i));
265 if (scratch_i != *merge_cp_length_p) {
266 // The new entry in *merge_cp_p is at a different index than
267 // the new entry in scratch_cp so we need to map the index values.
268 map_index(scratch_cp, scratch_i, *merge_cp_length_p);
269 }
270 (*merge_cp_length_p)++;
271 } break;
273 // these are direct CP entries so they can be directly appended,
274 // but double and long take two constant pool entries
275 case JVM_CONSTANT_Double: // fall through
276 case JVM_CONSTANT_Long:
277 {
278 ConstantPool::copy_entry_to(scratch_cp, scratch_i, *merge_cp_p, *merge_cp_length_p,
279 THREAD);
281 if (scratch_i != *merge_cp_length_p) {
282 // The new entry in *merge_cp_p is at a different index than
283 // the new entry in scratch_cp so we need to map the index values.
284 map_index(scratch_cp, scratch_i, *merge_cp_length_p);
285 }
286 (*merge_cp_length_p) += 2;
287 } break;
289 // these are direct CP entries so they can be directly appended
290 case JVM_CONSTANT_Float: // fall through
291 case JVM_CONSTANT_Integer: // fall through
292 case JVM_CONSTANT_Utf8: // fall through
294 // This was an indirect CP entry, but it has been changed into
295 // Symbol*s so this entry can be directly appended.
296 case JVM_CONSTANT_String: // fall through
298 // These were indirect CP entries, but they have been changed into
299 // Symbol*s so these entries can be directly appended.
300 case JVM_CONSTANT_UnresolvedClass: // fall through
301 {
302 ConstantPool::copy_entry_to(scratch_cp, scratch_i, *merge_cp_p, *merge_cp_length_p,
303 THREAD);
305 if (scratch_i != *merge_cp_length_p) {
306 // The new entry in *merge_cp_p is at a different index than
307 // the new entry in scratch_cp so we need to map the index values.
308 map_index(scratch_cp, scratch_i, *merge_cp_length_p);
309 }
310 (*merge_cp_length_p)++;
311 } break;
313 // this is an indirect CP entry so it needs special handling
314 case JVM_CONSTANT_NameAndType:
315 {
316 int name_ref_i = scratch_cp->name_ref_index_at(scratch_i);
317 int new_name_ref_i = 0;
318 bool match = (name_ref_i < *merge_cp_length_p) &&
319 scratch_cp->compare_entry_to(name_ref_i, *merge_cp_p, name_ref_i,
320 THREAD);
321 if (!match) {
322 // forward reference in *merge_cp_p or not a direct match
324 int found_i = scratch_cp->find_matching_entry(name_ref_i, *merge_cp_p,
325 THREAD);
326 if (found_i != 0) {
327 guarantee(found_i != name_ref_i,
328 "compare_entry_to() and find_matching_entry() do not agree");
330 // Found a matching entry somewhere else in *merge_cp_p so
331 // just need a mapping entry.
332 new_name_ref_i = found_i;
333 map_index(scratch_cp, name_ref_i, found_i);
334 } else {
335 // no match found so we have to append this entry to *merge_cp_p
336 append_entry(scratch_cp, name_ref_i, merge_cp_p, merge_cp_length_p,
337 THREAD);
338 // The above call to append_entry() can only append one entry
339 // so the post call query of *merge_cp_length_p is only for
340 // the sake of consistency.
341 new_name_ref_i = *merge_cp_length_p - 1;
342 }
343 }
345 int signature_ref_i = scratch_cp->signature_ref_index_at(scratch_i);
346 int new_signature_ref_i = 0;
347 match = (signature_ref_i < *merge_cp_length_p) &&
348 scratch_cp->compare_entry_to(signature_ref_i, *merge_cp_p,
349 signature_ref_i, THREAD);
350 if (!match) {
351 // forward reference in *merge_cp_p or not a direct match
353 int found_i = scratch_cp->find_matching_entry(signature_ref_i,
354 *merge_cp_p, THREAD);
355 if (found_i != 0) {
356 guarantee(found_i != signature_ref_i,
357 "compare_entry_to() and find_matching_entry() do not agree");
359 // Found a matching entry somewhere else in *merge_cp_p so
360 // just need a mapping entry.
361 new_signature_ref_i = found_i;
362 map_index(scratch_cp, signature_ref_i, found_i);
363 } else {
364 // no match found so we have to append this entry to *merge_cp_p
365 append_entry(scratch_cp, signature_ref_i, merge_cp_p,
366 merge_cp_length_p, THREAD);
367 // The above call to append_entry() can only append one entry
368 // so the post call query of *merge_cp_length_p is only for
369 // the sake of consistency.
370 new_signature_ref_i = *merge_cp_length_p - 1;
371 }
372 }
374 // If the referenced entries already exist in *merge_cp_p, then
375 // both new_name_ref_i and new_signature_ref_i will both be 0.
376 // In that case, all we are appending is the current entry.
377 if (new_name_ref_i == 0) {
378 new_name_ref_i = name_ref_i;
379 } else {
380 RC_TRACE(0x00080000,
381 ("NameAndType entry@%d name_ref_index change: %d to %d",
382 *merge_cp_length_p, name_ref_i, new_name_ref_i));
383 }
384 if (new_signature_ref_i == 0) {
385 new_signature_ref_i = signature_ref_i;
386 } else {
387 RC_TRACE(0x00080000,
388 ("NameAndType entry@%d signature_ref_index change: %d to %d",
389 *merge_cp_length_p, signature_ref_i, new_signature_ref_i));
390 }
392 (*merge_cp_p)->name_and_type_at_put(*merge_cp_length_p,
393 new_name_ref_i, new_signature_ref_i);
394 if (scratch_i != *merge_cp_length_p) {
395 // The new entry in *merge_cp_p is at a different index than
396 // the new entry in scratch_cp so we need to map the index values.
397 map_index(scratch_cp, scratch_i, *merge_cp_length_p);
398 }
399 (*merge_cp_length_p)++;
400 } break;
402 // this is a double-indirect CP entry so it needs special handling
403 case JVM_CONSTANT_Fieldref: // fall through
404 case JVM_CONSTANT_InterfaceMethodref: // fall through
405 case JVM_CONSTANT_Methodref:
406 {
407 int klass_ref_i = scratch_cp->uncached_klass_ref_index_at(scratch_i);
408 int new_klass_ref_i = 0;
409 bool match = (klass_ref_i < *merge_cp_length_p) &&
410 scratch_cp->compare_entry_to(klass_ref_i, *merge_cp_p, klass_ref_i,
411 THREAD);
412 if (!match) {
413 // forward reference in *merge_cp_p or not a direct match
415 int found_i = scratch_cp->find_matching_entry(klass_ref_i, *merge_cp_p,
416 THREAD);
417 if (found_i != 0) {
418 guarantee(found_i != klass_ref_i,
419 "compare_entry_to() and find_matching_entry() do not agree");
421 // Found a matching entry somewhere else in *merge_cp_p so
422 // just need a mapping entry.
423 new_klass_ref_i = found_i;
424 map_index(scratch_cp, klass_ref_i, found_i);
425 } else {
426 // no match found so we have to append this entry to *merge_cp_p
427 append_entry(scratch_cp, klass_ref_i, merge_cp_p, merge_cp_length_p,
428 THREAD);
429 // The above call to append_entry() can only append one entry
430 // so the post call query of *merge_cp_length_p is only for
431 // the sake of consistency. Without the optimization where we
432 // use JVM_CONSTANT_UnresolvedClass, then up to two entries
433 // could be appended.
434 new_klass_ref_i = *merge_cp_length_p - 1;
435 }
436 }
438 int name_and_type_ref_i =
439 scratch_cp->uncached_name_and_type_ref_index_at(scratch_i);
440 int new_name_and_type_ref_i = 0;
441 match = (name_and_type_ref_i < *merge_cp_length_p) &&
442 scratch_cp->compare_entry_to(name_and_type_ref_i, *merge_cp_p,
443 name_and_type_ref_i, THREAD);
444 if (!match) {
445 // forward reference in *merge_cp_p or not a direct match
447 int found_i = scratch_cp->find_matching_entry(name_and_type_ref_i,
448 *merge_cp_p, THREAD);
449 if (found_i != 0) {
450 guarantee(found_i != name_and_type_ref_i,
451 "compare_entry_to() and find_matching_entry() do not agree");
453 // Found a matching entry somewhere else in *merge_cp_p so
454 // just need a mapping entry.
455 new_name_and_type_ref_i = found_i;
456 map_index(scratch_cp, name_and_type_ref_i, found_i);
457 } else {
458 // no match found so we have to append this entry to *merge_cp_p
459 append_entry(scratch_cp, name_and_type_ref_i, merge_cp_p,
460 merge_cp_length_p, THREAD);
461 // The above call to append_entry() can append more than
462 // one entry so the post call query of *merge_cp_length_p
463 // is required in order to get the right index for the
464 // JVM_CONSTANT_NameAndType entry.
465 new_name_and_type_ref_i = *merge_cp_length_p - 1;
466 }
467 }
469 // If the referenced entries already exist in *merge_cp_p, then
470 // both new_klass_ref_i and new_name_and_type_ref_i will both be
471 // 0. In that case, all we are appending is the current entry.
472 if (new_klass_ref_i == 0) {
473 new_klass_ref_i = klass_ref_i;
474 }
475 if (new_name_and_type_ref_i == 0) {
476 new_name_and_type_ref_i = name_and_type_ref_i;
477 }
479 const char *entry_name;
480 switch (scratch_cp->tag_at(scratch_i).value()) {
481 case JVM_CONSTANT_Fieldref:
482 entry_name = "Fieldref";
483 (*merge_cp_p)->field_at_put(*merge_cp_length_p, new_klass_ref_i,
484 new_name_and_type_ref_i);
485 break;
486 case JVM_CONSTANT_InterfaceMethodref:
487 entry_name = "IFMethodref";
488 (*merge_cp_p)->interface_method_at_put(*merge_cp_length_p,
489 new_klass_ref_i, new_name_and_type_ref_i);
490 break;
491 case JVM_CONSTANT_Methodref:
492 entry_name = "Methodref";
493 (*merge_cp_p)->method_at_put(*merge_cp_length_p, new_klass_ref_i,
494 new_name_and_type_ref_i);
495 break;
496 default:
497 guarantee(false, "bad switch");
498 break;
499 }
501 if (klass_ref_i != new_klass_ref_i) {
502 RC_TRACE(0x00080000, ("%s entry@%d class_index changed: %d to %d",
503 entry_name, *merge_cp_length_p, klass_ref_i, new_klass_ref_i));
504 }
505 if (name_and_type_ref_i != new_name_and_type_ref_i) {
506 RC_TRACE(0x00080000,
507 ("%s entry@%d name_and_type_index changed: %d to %d",
508 entry_name, *merge_cp_length_p, name_and_type_ref_i,
509 new_name_and_type_ref_i));
510 }
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;
520 // At this stage, Class or UnresolvedClass could be here, but not
521 // ClassIndex
522 case JVM_CONSTANT_ClassIndex: // fall through
524 // Invalid is used as the tag for the second constant pool entry
525 // occupied by JVM_CONSTANT_Double or JVM_CONSTANT_Long. It should
526 // not be seen by itself.
527 case JVM_CONSTANT_Invalid: // fall through
529 // At this stage, String could be here, but not StringIndex
530 case JVM_CONSTANT_StringIndex: // fall through
532 // At this stage JVM_CONSTANT_UnresolvedClassInError should not be
533 // here
534 case JVM_CONSTANT_UnresolvedClassInError: // fall through
536 default:
537 {
538 // leave a breadcrumb
539 jbyte bad_value = scratch_cp->tag_at(scratch_i).value();
540 ShouldNotReachHere();
541 } break;
542 } // end switch tag value
543 } // end append_entry()
546 void VM_RedefineClasses::swap_all_method_annotations(int i, int j, instanceKlassHandle scratch_class, TRAPS) {
547 AnnotationArray* save;
549 Annotations* sca = scratch_class->annotations();
550 if (sca == NULL) return;
552 save = sca->get_method_annotations_of(i);
553 sca->set_method_annotations_of(scratch_class, i, sca->get_method_annotations_of(j), CHECK);
554 sca->set_method_annotations_of(scratch_class, j, save, CHECK);
556 save = sca->get_method_parameter_annotations_of(i);
557 sca->set_method_parameter_annotations_of(scratch_class, i, sca->get_method_parameter_annotations_of(j), CHECK);
558 sca->set_method_parameter_annotations_of(scratch_class, j, save, CHECK);
560 save = sca->get_method_default_annotations_of(i);
561 sca->set_method_default_annotations_of(scratch_class, i, sca->get_method_default_annotations_of(j), CHECK);
562 sca->set_method_default_annotations_of(scratch_class, j, save, CHECK);
563 }
566 jvmtiError VM_RedefineClasses::compare_and_normalize_class_versions(
567 instanceKlassHandle the_class,
568 instanceKlassHandle scratch_class) {
569 int i;
571 // Check superclasses, or rather their names, since superclasses themselves can be
572 // requested to replace.
573 // Check for NULL superclass first since this might be java.lang.Object
574 if (the_class->super() != scratch_class->super() &&
575 (the_class->super() == NULL || scratch_class->super() == NULL ||
576 the_class->super()->name() !=
577 scratch_class->super()->name())) {
578 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_HIERARCHY_CHANGED;
579 }
581 // Check if the number, names and order of directly implemented interfaces are the same.
582 // I think in principle we should just check if the sets of names of directly implemented
583 // interfaces are the same, i.e. the order of declaration (which, however, if changed in the
584 // .java file, also changes in .class file) should not matter. However, comparing sets is
585 // technically a bit more difficult, and, more importantly, I am not sure at present that the
586 // order of interfaces does not matter on the implementation level, i.e. that the VM does not
587 // rely on it somewhere.
588 Array<Klass*>* k_interfaces = the_class->local_interfaces();
589 Array<Klass*>* k_new_interfaces = scratch_class->local_interfaces();
590 int n_intfs = k_interfaces->length();
591 if (n_intfs != k_new_interfaces->length()) {
592 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_HIERARCHY_CHANGED;
593 }
594 for (i = 0; i < n_intfs; i++) {
595 if (k_interfaces->at(i)->name() !=
596 k_new_interfaces->at(i)->name()) {
597 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_HIERARCHY_CHANGED;
598 }
599 }
601 // Check whether class is in the error init state.
602 if (the_class->is_in_error_state()) {
603 // TBD #5057930: special error code is needed in 1.6
604 return JVMTI_ERROR_INVALID_CLASS;
605 }
607 // Check whether class modifiers are the same.
608 jushort old_flags = (jushort) the_class->access_flags().get_flags();
609 jushort new_flags = (jushort) scratch_class->access_flags().get_flags();
610 if (old_flags != new_flags) {
611 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_CLASS_MODIFIERS_CHANGED;
612 }
614 // Check if the number, names, types and order of fields declared in these classes
615 // are the same.
616 JavaFieldStream old_fs(the_class);
617 JavaFieldStream new_fs(scratch_class);
618 for (; !old_fs.done() && !new_fs.done(); old_fs.next(), new_fs.next()) {
619 // access
620 old_flags = old_fs.access_flags().as_short();
621 new_flags = new_fs.access_flags().as_short();
622 if ((old_flags ^ new_flags) & JVM_RECOGNIZED_FIELD_MODIFIERS) {
623 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_SCHEMA_CHANGED;
624 }
625 // offset
626 if (old_fs.offset() != new_fs.offset()) {
627 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_SCHEMA_CHANGED;
628 }
629 // name and signature
630 Symbol* name_sym1 = the_class->constants()->symbol_at(old_fs.name_index());
631 Symbol* sig_sym1 = the_class->constants()->symbol_at(old_fs.signature_index());
632 Symbol* name_sym2 = scratch_class->constants()->symbol_at(new_fs.name_index());
633 Symbol* sig_sym2 = scratch_class->constants()->symbol_at(new_fs.signature_index());
634 if (name_sym1 != name_sym2 || sig_sym1 != sig_sym2) {
635 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_SCHEMA_CHANGED;
636 }
637 }
639 // If both streams aren't done then we have a differing number of
640 // fields.
641 if (!old_fs.done() || !new_fs.done()) {
642 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_SCHEMA_CHANGED;
643 }
645 // Do a parallel walk through the old and new methods. Detect
646 // cases where they match (exist in both), have been added in
647 // the new methods, or have been deleted (exist only in the
648 // old methods). The class file parser places methods in order
649 // by method name, but does not order overloaded methods by
650 // signature. In order to determine what fate befell the methods,
651 // this code places the overloaded new methods that have matching
652 // old methods in the same order as the old methods and places
653 // new overloaded methods at the end of overloaded methods of
654 // that name. The code for this order normalization is adapted
655 // from the algorithm used in InstanceKlass::find_method().
656 // Since we are swapping out of order entries as we find them,
657 // we only have to search forward through the overloaded methods.
658 // Methods which are added and have the same name as an existing
659 // method (but different signature) will be put at the end of
660 // the methods with that name, and the name mismatch code will
661 // handle them.
662 Array<Method*>* k_old_methods(the_class->methods());
663 Array<Method*>* k_new_methods(scratch_class->methods());
664 int n_old_methods = k_old_methods->length();
665 int n_new_methods = k_new_methods->length();
666 Thread* thread = Thread::current();
668 int ni = 0;
669 int oi = 0;
670 while (true) {
671 Method* k_old_method;
672 Method* k_new_method;
673 enum { matched, added, deleted, undetermined } method_was = undetermined;
675 if (oi >= n_old_methods) {
676 if (ni >= n_new_methods) {
677 break; // we've looked at everything, done
678 }
679 // New method at the end
680 k_new_method = k_new_methods->at(ni);
681 method_was = added;
682 } else if (ni >= n_new_methods) {
683 // Old method, at the end, is deleted
684 k_old_method = k_old_methods->at(oi);
685 method_was = deleted;
686 } else {
687 // There are more methods in both the old and new lists
688 k_old_method = k_old_methods->at(oi);
689 k_new_method = k_new_methods->at(ni);
690 if (k_old_method->name() != k_new_method->name()) {
691 // Methods are sorted by method name, so a mismatch means added
692 // or deleted
693 if (k_old_method->name()->fast_compare(k_new_method->name()) > 0) {
694 method_was = added;
695 } else {
696 method_was = deleted;
697 }
698 } else if (k_old_method->signature() == k_new_method->signature()) {
699 // Both the name and signature match
700 method_was = matched;
701 } else {
702 // The name matches, but the signature doesn't, which means we have to
703 // search forward through the new overloaded methods.
704 int nj; // outside the loop for post-loop check
705 for (nj = ni + 1; nj < n_new_methods; nj++) {
706 Method* m = k_new_methods->at(nj);
707 if (k_old_method->name() != m->name()) {
708 // reached another method name so no more overloaded methods
709 method_was = deleted;
710 break;
711 }
712 if (k_old_method->signature() == m->signature()) {
713 // found a match so swap the methods
714 k_new_methods->at_put(ni, m);
715 k_new_methods->at_put(nj, k_new_method);
716 k_new_method = m;
717 method_was = matched;
718 break;
719 }
720 }
722 if (nj >= n_new_methods) {
723 // reached the end without a match; so method was deleted
724 method_was = deleted;
725 }
726 }
727 }
729 switch (method_was) {
730 case matched:
731 // methods match, be sure modifiers do too
732 old_flags = (jushort) k_old_method->access_flags().get_flags();
733 new_flags = (jushort) k_new_method->access_flags().get_flags();
734 if ((old_flags ^ new_flags) & ~(JVM_ACC_NATIVE)) {
735 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_METHOD_MODIFIERS_CHANGED;
736 }
737 {
738 u2 new_num = k_new_method->method_idnum();
739 u2 old_num = k_old_method->method_idnum();
740 if (new_num != old_num) {
741 Method* idnum_owner = scratch_class->method_with_idnum(old_num);
742 if (idnum_owner != NULL) {
743 // There is already a method assigned this idnum -- switch them
744 idnum_owner->set_method_idnum(new_num);
745 }
746 k_new_method->set_method_idnum(old_num);
747 swap_all_method_annotations(old_num, new_num, scratch_class, thread);
748 if (thread->has_pending_exception()) {
749 return JVMTI_ERROR_OUT_OF_MEMORY;
750 }
751 }
752 }
753 RC_TRACE(0x00008000, ("Method matched: new: %s [%d] == old: %s [%d]",
754 k_new_method->name_and_sig_as_C_string(), ni,
755 k_old_method->name_and_sig_as_C_string(), oi));
756 // advance to next pair of methods
757 ++oi;
758 ++ni;
759 break;
760 case added:
761 // method added, see if it is OK
762 new_flags = (jushort) k_new_method->access_flags().get_flags();
763 if ((new_flags & JVM_ACC_PRIVATE) == 0
764 // hack: private should be treated as final, but alas
765 || (new_flags & (JVM_ACC_FINAL|JVM_ACC_STATIC)) == 0
766 ) {
767 // new methods must be private
768 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_METHOD_ADDED;
769 }
770 {
771 u2 num = the_class->next_method_idnum();
772 if (num == ConstMethod::UNSET_IDNUM) {
773 // cannot add any more methods
774 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_METHOD_ADDED;
775 }
776 u2 new_num = k_new_method->method_idnum();
777 Method* idnum_owner = scratch_class->method_with_idnum(num);
778 if (idnum_owner != NULL) {
779 // There is already a method assigned this idnum -- switch them
780 idnum_owner->set_method_idnum(new_num);
781 }
782 k_new_method->set_method_idnum(num);
783 swap_all_method_annotations(new_num, num, scratch_class, thread);
784 if (thread->has_pending_exception()) {
785 return JVMTI_ERROR_OUT_OF_MEMORY;
786 }
787 }
788 RC_TRACE(0x00008000, ("Method added: new: %s [%d]",
789 k_new_method->name_and_sig_as_C_string(), ni));
790 ++ni; // advance to next new method
791 break;
792 case deleted:
793 // method deleted, see if it is OK
794 old_flags = (jushort) k_old_method->access_flags().get_flags();
795 if ((old_flags & JVM_ACC_PRIVATE) == 0
796 // hack: private should be treated as final, but alas
797 || (old_flags & (JVM_ACC_FINAL|JVM_ACC_STATIC)) == 0
798 ) {
799 // deleted methods must be private
800 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_METHOD_DELETED;
801 }
802 RC_TRACE(0x00008000, ("Method deleted: old: %s [%d]",
803 k_old_method->name_and_sig_as_C_string(), oi));
804 ++oi; // advance to next old method
805 break;
806 default:
807 ShouldNotReachHere();
808 }
809 }
811 return JVMTI_ERROR_NONE;
812 }
815 // Find new constant pool index value for old constant pool index value
816 // by seaching the index map. Returns zero (0) if there is no mapped
817 // value for the old constant pool index.
818 int VM_RedefineClasses::find_new_index(int old_index) {
819 if (_index_map_count == 0) {
820 // map is empty so nothing can be found
821 return 0;
822 }
824 if (old_index < 1 || old_index >= _index_map_p->length()) {
825 // The old_index is out of range so it is not mapped. This should
826 // not happen in regular constant pool merging use, but it can
827 // happen if a corrupt annotation is processed.
828 return 0;
829 }
831 int value = _index_map_p->at(old_index);
832 if (value == -1) {
833 // the old_index is not mapped
834 return 0;
835 }
837 return value;
838 } // end find_new_index()
841 // Returns true if the current mismatch is due to a resolved/unresolved
842 // class pair. Otherwise, returns false.
843 bool VM_RedefineClasses::is_unresolved_class_mismatch(constantPoolHandle cp1,
844 int index1, constantPoolHandle cp2, int index2) {
846 jbyte t1 = cp1->tag_at(index1).value();
847 if (t1 != JVM_CONSTANT_Class && t1 != JVM_CONSTANT_UnresolvedClass) {
848 return false; // wrong entry type; not our special case
849 }
851 jbyte t2 = cp2->tag_at(index2).value();
852 if (t2 != JVM_CONSTANT_Class && t2 != JVM_CONSTANT_UnresolvedClass) {
853 return false; // wrong entry type; not our special case
854 }
856 if (t1 == t2) {
857 return false; // not a mismatch; not our special case
858 }
860 char *s1 = cp1->klass_name_at(index1)->as_C_string();
861 char *s2 = cp2->klass_name_at(index2)->as_C_string();
862 if (strcmp(s1, s2) != 0) {
863 return false; // strings don't match; not our special case
864 }
866 return true; // made it through the gauntlet; this is our special case
867 } // end is_unresolved_class_mismatch()
870 jvmtiError VM_RedefineClasses::load_new_class_versions(TRAPS) {
872 // For consistency allocate memory using os::malloc wrapper.
873 _scratch_classes = (Klass**)
874 os::malloc(sizeof(Klass*) * _class_count, mtClass);
875 if (_scratch_classes == NULL) {
876 return JVMTI_ERROR_OUT_OF_MEMORY;
877 }
878 // Zero initialize the _scratch_classes array.
879 for (int i = 0; i < _class_count; i++) {
880 _scratch_classes[i] = NULL;
881 }
883 ResourceMark rm(THREAD);
885 JvmtiThreadState *state = JvmtiThreadState::state_for(JavaThread::current());
886 // state can only be NULL if the current thread is exiting which
887 // should not happen since we're trying to do a RedefineClasses
888 guarantee(state != NULL, "exiting thread calling load_new_class_versions");
889 for (int i = 0; i < _class_count; i++) {
890 // Create HandleMark so that any handles created while loading new class
891 // versions are deleted. Constant pools are deallocated while merging
892 // constant pools
893 HandleMark hm(THREAD);
895 oop mirror = JNIHandles::resolve_non_null(_class_defs[i].klass);
896 // classes for primitives cannot be redefined
897 if (!is_modifiable_class(mirror)) {
898 return JVMTI_ERROR_UNMODIFIABLE_CLASS;
899 }
900 Klass* the_class_oop = java_lang_Class::as_Klass(mirror);
901 instanceKlassHandle the_class = instanceKlassHandle(THREAD, the_class_oop);
902 Symbol* the_class_sym = the_class->name();
904 // RC_TRACE_WITH_THREAD macro has an embedded ResourceMark
905 RC_TRACE_WITH_THREAD(0x00000001, THREAD,
906 ("loading name=%s kind=%d (avail_mem=" UINT64_FORMAT "K)",
907 the_class->external_name(), _class_load_kind,
908 os::available_memory() >> 10));
910 ClassFileStream st((u1*) _class_defs[i].class_bytes,
911 _class_defs[i].class_byte_count, (char *)"__VM_RedefineClasses__");
913 // Parse the stream.
914 Handle the_class_loader(THREAD, the_class->class_loader());
915 Handle protection_domain(THREAD, the_class->protection_domain());
916 // Set redefined class handle in JvmtiThreadState class.
917 // This redefined class is sent to agent event handler for class file
918 // load hook event.
919 state->set_class_being_redefined(&the_class, _class_load_kind);
921 Klass* k = SystemDictionary::parse_stream(the_class_sym,
922 the_class_loader,
923 protection_domain,
924 &st,
925 THREAD);
926 // Clear class_being_redefined just to be sure.
927 state->clear_class_being_redefined();
929 // TODO: if this is retransform, and nothing changed we can skip it
931 instanceKlassHandle scratch_class (THREAD, k);
933 // Need to clean up allocated InstanceKlass if there's an error so assign
934 // the result here. Caller deallocates all the scratch classes in case of
935 // an error.
936 _scratch_classes[i] = k;
938 if (HAS_PENDING_EXCEPTION) {
939 Symbol* ex_name = PENDING_EXCEPTION->klass()->name();
940 // RC_TRACE_WITH_THREAD macro has an embedded ResourceMark
941 RC_TRACE_WITH_THREAD(0x00000002, THREAD, ("parse_stream exception: '%s'",
942 ex_name->as_C_string()));
943 CLEAR_PENDING_EXCEPTION;
945 if (ex_name == vmSymbols::java_lang_UnsupportedClassVersionError()) {
946 return JVMTI_ERROR_UNSUPPORTED_VERSION;
947 } else if (ex_name == vmSymbols::java_lang_ClassFormatError()) {
948 return JVMTI_ERROR_INVALID_CLASS_FORMAT;
949 } else if (ex_name == vmSymbols::java_lang_ClassCircularityError()) {
950 return JVMTI_ERROR_CIRCULAR_CLASS_DEFINITION;
951 } else if (ex_name == vmSymbols::java_lang_NoClassDefFoundError()) {
952 // The message will be "XXX (wrong name: YYY)"
953 return JVMTI_ERROR_NAMES_DONT_MATCH;
954 } else if (ex_name == vmSymbols::java_lang_OutOfMemoryError()) {
955 return JVMTI_ERROR_OUT_OF_MEMORY;
956 } else { // Just in case more exceptions can be thrown..
957 return JVMTI_ERROR_FAILS_VERIFICATION;
958 }
959 }
961 // Ensure class is linked before redefine
962 if (!the_class->is_linked()) {
963 the_class->link_class(THREAD);
964 if (HAS_PENDING_EXCEPTION) {
965 Symbol* ex_name = PENDING_EXCEPTION->klass()->name();
966 // RC_TRACE_WITH_THREAD macro has an embedded ResourceMark
967 RC_TRACE_WITH_THREAD(0x00000002, THREAD, ("link_class exception: '%s'",
968 ex_name->as_C_string()));
969 CLEAR_PENDING_EXCEPTION;
970 if (ex_name == vmSymbols::java_lang_OutOfMemoryError()) {
971 return JVMTI_ERROR_OUT_OF_MEMORY;
972 } else {
973 return JVMTI_ERROR_INTERNAL;
974 }
975 }
976 }
978 // Do the validity checks in compare_and_normalize_class_versions()
979 // before verifying the byte codes. By doing these checks first, we
980 // limit the number of functions that require redirection from
981 // the_class to scratch_class. In particular, we don't have to
982 // modify JNI GetSuperclass() and thus won't change its performance.
983 jvmtiError res = compare_and_normalize_class_versions(the_class,
984 scratch_class);
985 if (res != JVMTI_ERROR_NONE) {
986 return res;
987 }
989 // verify what the caller passed us
990 {
991 // The bug 6214132 caused the verification to fail.
992 // Information about the_class and scratch_class is temporarily
993 // recorded into jvmtiThreadState. This data is used to redirect
994 // the_class to scratch_class in the JVM_* functions called by the
995 // verifier. Please, refer to jvmtiThreadState.hpp for the detailed
996 // description.
997 RedefineVerifyMark rvm(&the_class, &scratch_class, state);
998 Verifier::verify(
999 scratch_class, Verifier::ThrowException, true, THREAD);
1000 }
1002 if (HAS_PENDING_EXCEPTION) {
1003 Symbol* ex_name = PENDING_EXCEPTION->klass()->name();
1004 // RC_TRACE_WITH_THREAD macro has an embedded ResourceMark
1005 RC_TRACE_WITH_THREAD(0x00000002, THREAD,
1006 ("verify_byte_codes exception: '%s'", ex_name->as_C_string()));
1007 CLEAR_PENDING_EXCEPTION;
1008 if (ex_name == vmSymbols::java_lang_OutOfMemoryError()) {
1009 return JVMTI_ERROR_OUT_OF_MEMORY;
1010 } else {
1011 // tell the caller the bytecodes are bad
1012 return JVMTI_ERROR_FAILS_VERIFICATION;
1013 }
1014 }
1016 res = merge_cp_and_rewrite(the_class, scratch_class, THREAD);
1017 if (res != JVMTI_ERROR_NONE) {
1018 return res;
1019 }
1021 if (VerifyMergedCPBytecodes) {
1022 // verify what we have done during constant pool merging
1023 {
1024 RedefineVerifyMark rvm(&the_class, &scratch_class, state);
1025 Verifier::verify(scratch_class, Verifier::ThrowException, true, THREAD);
1026 }
1028 if (HAS_PENDING_EXCEPTION) {
1029 Symbol* ex_name = PENDING_EXCEPTION->klass()->name();
1030 // RC_TRACE_WITH_THREAD macro has an embedded ResourceMark
1031 RC_TRACE_WITH_THREAD(0x00000002, THREAD,
1032 ("verify_byte_codes post merge-CP exception: '%s'",
1033 ex_name->as_C_string()));
1034 CLEAR_PENDING_EXCEPTION;
1035 if (ex_name == vmSymbols::java_lang_OutOfMemoryError()) {
1036 return JVMTI_ERROR_OUT_OF_MEMORY;
1037 } else {
1038 // tell the caller that constant pool merging screwed up
1039 return JVMTI_ERROR_INTERNAL;
1040 }
1041 }
1042 }
1044 Rewriter::rewrite(scratch_class, THREAD);
1045 if (!HAS_PENDING_EXCEPTION) {
1046 Rewriter::relocate_and_link(scratch_class, THREAD);
1047 }
1048 if (HAS_PENDING_EXCEPTION) {
1049 Symbol* ex_name = PENDING_EXCEPTION->klass()->name();
1050 CLEAR_PENDING_EXCEPTION;
1051 if (ex_name == vmSymbols::java_lang_OutOfMemoryError()) {
1052 return JVMTI_ERROR_OUT_OF_MEMORY;
1053 } else {
1054 return JVMTI_ERROR_INTERNAL;
1055 }
1056 }
1058 // RC_TRACE_WITH_THREAD macro has an embedded ResourceMark
1059 RC_TRACE_WITH_THREAD(0x00000001, THREAD,
1060 ("loaded name=%s (avail_mem=" UINT64_FORMAT "K)",
1061 the_class->external_name(), os::available_memory() >> 10));
1062 }
1064 return JVMTI_ERROR_NONE;
1065 }
1068 // Map old_index to new_index as needed. scratch_cp is only needed
1069 // for RC_TRACE() calls.
1070 void VM_RedefineClasses::map_index(constantPoolHandle scratch_cp,
1071 int old_index, int new_index) {
1072 if (find_new_index(old_index) != 0) {
1073 // old_index is already mapped
1074 return;
1075 }
1077 if (old_index == new_index) {
1078 // no mapping is needed
1079 return;
1080 }
1082 _index_map_p->at_put(old_index, new_index);
1083 _index_map_count++;
1085 RC_TRACE(0x00040000, ("mapped tag %d at index %d to %d",
1086 scratch_cp->tag_at(old_index).value(), old_index, new_index));
1087 } // end map_index()
1090 // Merge old_cp and scratch_cp and return the results of the merge via
1091 // merge_cp_p. The number of entries in *merge_cp_p is returned via
1092 // merge_cp_length_p. The entries in old_cp occupy the same locations
1093 // in *merge_cp_p. Also creates a map of indices from entries in
1094 // scratch_cp to the corresponding entry in *merge_cp_p. Index map
1095 // entries are only created for entries in scratch_cp that occupy a
1096 // different location in *merged_cp_p.
1097 bool VM_RedefineClasses::merge_constant_pools(constantPoolHandle old_cp,
1098 constantPoolHandle scratch_cp, constantPoolHandle *merge_cp_p,
1099 int *merge_cp_length_p, TRAPS) {
1101 if (merge_cp_p == NULL) {
1102 assert(false, "caller must provide scratch constantPool");
1103 return false; // robustness
1104 }
1105 if (merge_cp_length_p == NULL) {
1106 assert(false, "caller must provide scratch CP length");
1107 return false; // robustness
1108 }
1109 // Worst case we need old_cp->length() + scratch_cp()->length(),
1110 // but the caller might be smart so make sure we have at least
1111 // the minimum.
1112 if ((*merge_cp_p)->length() < old_cp->length()) {
1113 assert(false, "merge area too small");
1114 return false; // robustness
1115 }
1117 RC_TRACE_WITH_THREAD(0x00010000, THREAD,
1118 ("old_cp_len=%d, scratch_cp_len=%d", old_cp->length(),
1119 scratch_cp->length()));
1121 {
1122 // Pass 0:
1123 // The old_cp is copied to *merge_cp_p; this means that any code
1124 // using old_cp does not have to change. This work looks like a
1125 // perfect fit for ConstantPool*::copy_cp_to(), but we need to
1126 // handle one special case:
1127 // - revert JVM_CONSTANT_Class to JVM_CONSTANT_UnresolvedClass
1128 // This will make verification happy.
1130 int old_i; // index into old_cp
1132 // index zero (0) is not used in constantPools
1133 for (old_i = 1; old_i < old_cp->length(); old_i++) {
1134 // leave debugging crumb
1135 jbyte old_tag = old_cp->tag_at(old_i).value();
1136 switch (old_tag) {
1137 case JVM_CONSTANT_Class:
1138 case JVM_CONSTANT_UnresolvedClass:
1139 // revert the copy to JVM_CONSTANT_UnresolvedClass
1140 // May be resolving while calling this so do the same for
1141 // JVM_CONSTANT_UnresolvedClass (klass_name_at() deals with transition)
1142 (*merge_cp_p)->unresolved_klass_at_put(old_i,
1143 old_cp->klass_name_at(old_i));
1144 break;
1146 case JVM_CONSTANT_Double:
1147 case JVM_CONSTANT_Long:
1148 // just copy the entry to *merge_cp_p, but double and long take
1149 // two constant pool entries
1150 ConstantPool::copy_entry_to(old_cp, old_i, *merge_cp_p, old_i, CHECK_0);
1151 old_i++;
1152 break;
1154 default:
1155 // just copy the entry to *merge_cp_p
1156 ConstantPool::copy_entry_to(old_cp, old_i, *merge_cp_p, old_i, CHECK_0);
1157 break;
1158 }
1159 } // end for each old_cp entry
1161 // We don't need to sanity check that *merge_cp_length_p is within
1162 // *merge_cp_p bounds since we have the minimum on-entry check above.
1163 (*merge_cp_length_p) = old_i;
1164 }
1166 // merge_cp_len should be the same as old_cp->length() at this point
1167 // so this trace message is really a "warm-and-breathing" message.
1168 RC_TRACE_WITH_THREAD(0x00020000, THREAD,
1169 ("after pass 0: merge_cp_len=%d", *merge_cp_length_p));
1171 int scratch_i; // index into scratch_cp
1172 {
1173 // Pass 1a:
1174 // Compare scratch_cp entries to the old_cp entries that we have
1175 // already copied to *merge_cp_p. In this pass, we are eliminating
1176 // exact duplicates (matching entry at same index) so we only
1177 // compare entries in the common indice range.
1178 int increment = 1;
1179 int pass1a_length = MIN2(old_cp->length(), scratch_cp->length());
1180 for (scratch_i = 1; scratch_i < pass1a_length; scratch_i += increment) {
1181 switch (scratch_cp->tag_at(scratch_i).value()) {
1182 case JVM_CONSTANT_Double:
1183 case JVM_CONSTANT_Long:
1184 // double and long take two constant pool entries
1185 increment = 2;
1186 break;
1188 default:
1189 increment = 1;
1190 break;
1191 }
1193 bool match = scratch_cp->compare_entry_to(scratch_i, *merge_cp_p,
1194 scratch_i, CHECK_0);
1195 if (match) {
1196 // found a match at the same index so nothing more to do
1197 continue;
1198 } else if (is_unresolved_class_mismatch(scratch_cp, scratch_i,
1199 *merge_cp_p, scratch_i)) {
1200 // The mismatch in compare_entry_to() above is because of a
1201 // resolved versus unresolved class entry at the same index
1202 // with the same string value. Since Pass 0 reverted any
1203 // class entries to unresolved class entries in *merge_cp_p,
1204 // we go with the unresolved class entry.
1205 continue;
1206 }
1208 int found_i = scratch_cp->find_matching_entry(scratch_i, *merge_cp_p,
1209 CHECK_0);
1210 if (found_i != 0) {
1211 guarantee(found_i != scratch_i,
1212 "compare_entry_to() and find_matching_entry() do not agree");
1214 // Found a matching entry somewhere else in *merge_cp_p so
1215 // just need a mapping entry.
1216 map_index(scratch_cp, scratch_i, found_i);
1217 continue;
1218 }
1220 // The find_matching_entry() call above could fail to find a match
1221 // due to a resolved versus unresolved class or string entry situation
1222 // like we solved above with the is_unresolved_*_mismatch() calls.
1223 // However, we would have to call is_unresolved_*_mismatch() over
1224 // all of *merge_cp_p (potentially) and that doesn't seem to be
1225 // worth the time.
1227 // No match found so we have to append this entry and any unique
1228 // referenced entries to *merge_cp_p.
1229 append_entry(scratch_cp, scratch_i, merge_cp_p, merge_cp_length_p,
1230 CHECK_0);
1231 }
1232 }
1234 RC_TRACE_WITH_THREAD(0x00020000, THREAD,
1235 ("after pass 1a: merge_cp_len=%d, scratch_i=%d, index_map_len=%d",
1236 *merge_cp_length_p, scratch_i, _index_map_count));
1238 if (scratch_i < scratch_cp->length()) {
1239 // Pass 1b:
1240 // old_cp is smaller than scratch_cp so there are entries in
1241 // scratch_cp that we have not yet processed. We take care of
1242 // those now.
1243 int increment = 1;
1244 for (; scratch_i < scratch_cp->length(); scratch_i += increment) {
1245 switch (scratch_cp->tag_at(scratch_i).value()) {
1246 case JVM_CONSTANT_Double:
1247 case JVM_CONSTANT_Long:
1248 // double and long take two constant pool entries
1249 increment = 2;
1250 break;
1252 default:
1253 increment = 1;
1254 break;
1255 }
1257 int found_i =
1258 scratch_cp->find_matching_entry(scratch_i, *merge_cp_p, CHECK_0);
1259 if (found_i != 0) {
1260 // Found a matching entry somewhere else in *merge_cp_p so
1261 // just need a mapping entry.
1262 map_index(scratch_cp, scratch_i, found_i);
1263 continue;
1264 }
1266 // No match found so we have to append this entry and any unique
1267 // referenced entries to *merge_cp_p.
1268 append_entry(scratch_cp, scratch_i, merge_cp_p, merge_cp_length_p,
1269 CHECK_0);
1270 }
1272 RC_TRACE_WITH_THREAD(0x00020000, THREAD,
1273 ("after pass 1b: merge_cp_len=%d, scratch_i=%d, index_map_len=%d",
1274 *merge_cp_length_p, scratch_i, _index_map_count));
1275 }
1277 return true;
1278 } // end merge_constant_pools()
1281 // Scoped object to clean up the constant pool(s) created for merging
1282 class MergeCPCleaner {
1283 ClassLoaderData* _loader_data;
1284 ConstantPool* _cp;
1285 ConstantPool* _scratch_cp;
1286 public:
1287 MergeCPCleaner(ClassLoaderData* loader_data, ConstantPool* merge_cp) :
1288 _loader_data(loader_data), _cp(merge_cp), _scratch_cp(NULL) {}
1289 ~MergeCPCleaner() {
1290 _loader_data->add_to_deallocate_list(_cp);
1291 if (_scratch_cp != NULL) {
1292 _loader_data->add_to_deallocate_list(_scratch_cp);
1293 }
1294 }
1295 void add_scratch_cp(ConstantPool* scratch_cp) { _scratch_cp = scratch_cp; }
1296 };
1298 // Merge constant pools between the_class and scratch_class and
1299 // potentially rewrite bytecodes in scratch_class to use the merged
1300 // constant pool.
1301 jvmtiError VM_RedefineClasses::merge_cp_and_rewrite(
1302 instanceKlassHandle the_class, instanceKlassHandle scratch_class,
1303 TRAPS) {
1304 // worst case merged constant pool length is old and new combined
1305 int merge_cp_length = the_class->constants()->length()
1306 + scratch_class->constants()->length();
1308 // Constant pools are not easily reused so we allocate a new one
1309 // each time.
1310 // merge_cp is created unsafe for concurrent GC processing. It
1311 // should be marked safe before discarding it. Even though
1312 // garbage, if it crosses a card boundary, it may be scanned
1313 // in order to find the start of the first complete object on the card.
1314 ClassLoaderData* loader_data = the_class->class_loader_data();
1315 ConstantPool* merge_cp_oop =
1316 ConstantPool::allocate(loader_data,
1317 merge_cp_length,
1318 THREAD);
1319 MergeCPCleaner cp_cleaner(loader_data, merge_cp_oop);
1321 HandleMark hm(THREAD); // make sure handles are cleared before
1322 // MergeCPCleaner clears out merge_cp_oop
1323 constantPoolHandle merge_cp(THREAD, merge_cp_oop);
1325 // Get constants() from the old class because it could have been rewritten
1326 // while we were at a safepoint allocating a new constant pool.
1327 constantPoolHandle old_cp(THREAD, the_class->constants());
1328 constantPoolHandle scratch_cp(THREAD, scratch_class->constants());
1330 // If the length changed, the class was redefined out from under us. Return
1331 // an error.
1332 if (merge_cp_length != the_class->constants()->length()
1333 + scratch_class->constants()->length()) {
1334 return JVMTI_ERROR_INTERNAL;
1335 }
1337 int orig_length = old_cp->orig_length();
1338 if (orig_length == 0) {
1339 // This old_cp is an actual original constant pool. We save
1340 // the original length in the merged constant pool so that
1341 // merge_constant_pools() can be more efficient. If a constant
1342 // pool has a non-zero orig_length() value, then that constant
1343 // pool was created by a merge operation in RedefineClasses.
1344 merge_cp->set_orig_length(old_cp->length());
1345 } else {
1346 // This old_cp is a merged constant pool from a previous
1347 // RedefineClasses() calls so just copy the orig_length()
1348 // value.
1349 merge_cp->set_orig_length(old_cp->orig_length());
1350 }
1352 ResourceMark rm(THREAD);
1353 _index_map_count = 0;
1354 _index_map_p = new intArray(scratch_cp->length(), -1);
1356 bool result = merge_constant_pools(old_cp, scratch_cp, &merge_cp,
1357 &merge_cp_length, THREAD);
1358 if (!result) {
1359 // The merge can fail due to memory allocation failure or due
1360 // to robustness checks.
1361 return JVMTI_ERROR_INTERNAL;
1362 }
1364 RC_TRACE_WITH_THREAD(0x00010000, THREAD,
1365 ("merge_cp_len=%d, index_map_len=%d", merge_cp_length, _index_map_count));
1367 if (_index_map_count == 0) {
1368 // there is nothing to map between the new and merged constant pools
1370 if (old_cp->length() == scratch_cp->length()) {
1371 // The old and new constant pools are the same length and the
1372 // index map is empty. This means that the three constant pools
1373 // are equivalent (but not the same). Unfortunately, the new
1374 // constant pool has not gone through link resolution nor have
1375 // the new class bytecodes gone through constant pool cache
1376 // rewriting so we can't use the old constant pool with the new
1377 // class.
1379 // toss the merged constant pool at return
1380 } else if (old_cp->length() < scratch_cp->length()) {
1381 // The old constant pool has fewer entries than the new constant
1382 // pool and the index map is empty. This means the new constant
1383 // pool is a superset of the old constant pool. However, the old
1384 // class bytecodes have already gone through constant pool cache
1385 // rewriting so we can't use the new constant pool with the old
1386 // class.
1388 // toss the merged constant pool at return
1389 } else {
1390 // The old constant pool has more entries than the new constant
1391 // pool and the index map is empty. This means that both the old
1392 // and merged constant pools are supersets of the new constant
1393 // pool.
1395 // Replace the new constant pool with a shrunken copy of the
1396 // merged constant pool
1397 set_new_constant_pool(loader_data, scratch_class, merge_cp, merge_cp_length, THREAD);
1398 // The new constant pool replaces scratch_cp so have cleaner clean it up.
1399 // It can't be cleaned up while there are handles to it.
1400 cp_cleaner.add_scratch_cp(scratch_cp());
1401 }
1402 } else {
1403 if (RC_TRACE_ENABLED(0x00040000)) {
1404 // don't want to loop unless we are tracing
1405 int count = 0;
1406 for (int i = 1; i < _index_map_p->length(); i++) {
1407 int value = _index_map_p->at(i);
1409 if (value != -1) {
1410 RC_TRACE_WITH_THREAD(0x00040000, THREAD,
1411 ("index_map[%d]: old=%d new=%d", count, i, value));
1412 count++;
1413 }
1414 }
1415 }
1417 // We have entries mapped between the new and merged constant pools
1418 // so we have to rewrite some constant pool references.
1419 if (!rewrite_cp_refs(scratch_class, THREAD)) {
1420 return JVMTI_ERROR_INTERNAL;
1421 }
1423 // Replace the new constant pool with a shrunken copy of the
1424 // merged constant pool so now the rewritten bytecodes have
1425 // valid references; the previous new constant pool will get
1426 // GCed.
1427 set_new_constant_pool(loader_data, scratch_class, merge_cp, merge_cp_length, THREAD);
1428 // The new constant pool replaces scratch_cp so have cleaner clean it up.
1429 // It can't be cleaned up while there are handles to it.
1430 cp_cleaner.add_scratch_cp(scratch_cp());
1431 }
1433 return JVMTI_ERROR_NONE;
1434 } // end merge_cp_and_rewrite()
1437 // Rewrite constant pool references in klass scratch_class.
1438 bool VM_RedefineClasses::rewrite_cp_refs(instanceKlassHandle scratch_class,
1439 TRAPS) {
1441 // rewrite constant pool references in the methods:
1442 if (!rewrite_cp_refs_in_methods(scratch_class, THREAD)) {
1443 // propagate failure back to caller
1444 return false;
1445 }
1447 // rewrite constant pool references in the class_annotations:
1448 if (!rewrite_cp_refs_in_class_annotations(scratch_class, THREAD)) {
1449 // propagate failure back to caller
1450 return false;
1451 }
1453 // rewrite constant pool references in the fields_annotations:
1454 if (!rewrite_cp_refs_in_fields_annotations(scratch_class, THREAD)) {
1455 // propagate failure back to caller
1456 return false;
1457 }
1459 // rewrite constant pool references in the methods_annotations:
1460 if (!rewrite_cp_refs_in_methods_annotations(scratch_class, THREAD)) {
1461 // propagate failure back to caller
1462 return false;
1463 }
1465 // rewrite constant pool references in the methods_parameter_annotations:
1466 if (!rewrite_cp_refs_in_methods_parameter_annotations(scratch_class,
1467 THREAD)) {
1468 // propagate failure back to caller
1469 return false;
1470 }
1472 // rewrite constant pool references in the methods_default_annotations:
1473 if (!rewrite_cp_refs_in_methods_default_annotations(scratch_class,
1474 THREAD)) {
1475 // propagate failure back to caller
1476 return false;
1477 }
1479 return true;
1480 } // end rewrite_cp_refs()
1483 // Rewrite constant pool references in the methods.
1484 bool VM_RedefineClasses::rewrite_cp_refs_in_methods(
1485 instanceKlassHandle scratch_class, TRAPS) {
1487 Array<Method*>* methods = scratch_class->methods();
1489 if (methods == NULL || methods->length() == 0) {
1490 // no methods so nothing to do
1491 return true;
1492 }
1494 // rewrite constant pool references in the methods:
1495 for (int i = methods->length() - 1; i >= 0; i--) {
1496 methodHandle method(THREAD, methods->at(i));
1497 methodHandle new_method;
1498 rewrite_cp_refs_in_method(method, &new_method, CHECK_false);
1499 if (!new_method.is_null()) {
1500 // the method has been replaced so save the new method version
1501 methods->at_put(i, new_method());
1502 }
1503 }
1505 return true;
1506 }
1509 // Rewrite constant pool references in the specific method. This code
1510 // was adapted from Rewriter::rewrite_method().
1511 void VM_RedefineClasses::rewrite_cp_refs_in_method(methodHandle method,
1512 methodHandle *new_method_p, TRAPS) {
1514 *new_method_p = methodHandle(); // default is no new method
1516 // We cache a pointer to the bytecodes here in code_base. If GC
1517 // moves the Method*, then the bytecodes will also move which
1518 // will likely cause a crash. We create a No_Safepoint_Verifier
1519 // object to detect whether we pass a possible safepoint in this
1520 // code block.
1521 No_Safepoint_Verifier nsv;
1523 // Bytecodes and their length
1524 address code_base = method->code_base();
1525 int code_length = method->code_size();
1527 int bc_length;
1528 for (int bci = 0; bci < code_length; bci += bc_length) {
1529 address bcp = code_base + bci;
1530 Bytecodes::Code c = (Bytecodes::Code)(*bcp);
1532 bc_length = Bytecodes::length_for(c);
1533 if (bc_length == 0) {
1534 // More complicated bytecodes report a length of zero so
1535 // we have to try again a slightly different way.
1536 bc_length = Bytecodes::length_at(method(), bcp);
1537 }
1539 assert(bc_length != 0, "impossible bytecode length");
1541 switch (c) {
1542 case Bytecodes::_ldc:
1543 {
1544 int cp_index = *(bcp + 1);
1545 int new_index = find_new_index(cp_index);
1547 if (StressLdcRewrite && new_index == 0) {
1548 // If we are stressing ldc -> ldc_w rewriting, then we
1549 // always need a new_index value.
1550 new_index = cp_index;
1551 }
1552 if (new_index != 0) {
1553 // the original index is mapped so we have more work to do
1554 if (!StressLdcRewrite && new_index <= max_jubyte) {
1555 // The new value can still use ldc instead of ldc_w
1556 // unless we are trying to stress ldc -> ldc_w rewriting
1557 RC_TRACE_WITH_THREAD(0x00080000, THREAD,
1558 ("%s@" INTPTR_FORMAT " old=%d, new=%d", Bytecodes::name(c),
1559 bcp, cp_index, new_index));
1560 *(bcp + 1) = new_index;
1561 } else {
1562 RC_TRACE_WITH_THREAD(0x00080000, THREAD,
1563 ("%s->ldc_w@" INTPTR_FORMAT " old=%d, new=%d",
1564 Bytecodes::name(c), bcp, cp_index, new_index));
1565 // the new value needs ldc_w instead of ldc
1566 u_char inst_buffer[4]; // max instruction size is 4 bytes
1567 bcp = (address)inst_buffer;
1568 // construct new instruction sequence
1569 *bcp = Bytecodes::_ldc_w;
1570 bcp++;
1571 // Rewriter::rewrite_method() does not rewrite ldc -> ldc_w.
1572 // See comment below for difference between put_Java_u2()
1573 // and put_native_u2().
1574 Bytes::put_Java_u2(bcp, new_index);
1576 Relocator rc(method, NULL /* no RelocatorListener needed */);
1577 methodHandle m;
1578 {
1579 Pause_No_Safepoint_Verifier pnsv(&nsv);
1581 // ldc is 2 bytes and ldc_w is 3 bytes
1582 m = rc.insert_space_at(bci, 3, inst_buffer, THREAD);
1583 if (m.is_null() || HAS_PENDING_EXCEPTION) {
1584 guarantee(false, "insert_space_at() failed");
1585 }
1586 }
1588 // return the new method so that the caller can update
1589 // the containing class
1590 *new_method_p = method = m;
1591 // switch our bytecode processing loop from the old method
1592 // to the new method
1593 code_base = method->code_base();
1594 code_length = method->code_size();
1595 bcp = code_base + bci;
1596 c = (Bytecodes::Code)(*bcp);
1597 bc_length = Bytecodes::length_for(c);
1598 assert(bc_length != 0, "sanity check");
1599 } // end we need ldc_w instead of ldc
1600 } // end if there is a mapped index
1601 } break;
1603 // these bytecodes have a two-byte constant pool index
1604 case Bytecodes::_anewarray : // fall through
1605 case Bytecodes::_checkcast : // fall through
1606 case Bytecodes::_getfield : // fall through
1607 case Bytecodes::_getstatic : // fall through
1608 case Bytecodes::_instanceof : // fall through
1609 case Bytecodes::_invokeinterface: // fall through
1610 case Bytecodes::_invokespecial : // fall through
1611 case Bytecodes::_invokestatic : // fall through
1612 case Bytecodes::_invokevirtual : // fall through
1613 case Bytecodes::_ldc_w : // fall through
1614 case Bytecodes::_ldc2_w : // fall through
1615 case Bytecodes::_multianewarray : // fall through
1616 case Bytecodes::_new : // fall through
1617 case Bytecodes::_putfield : // fall through
1618 case Bytecodes::_putstatic :
1619 {
1620 address p = bcp + 1;
1621 int cp_index = Bytes::get_Java_u2(p);
1622 int new_index = find_new_index(cp_index);
1623 if (new_index != 0) {
1624 // the original index is mapped so update w/ new value
1625 RC_TRACE_WITH_THREAD(0x00080000, THREAD,
1626 ("%s@" INTPTR_FORMAT " old=%d, new=%d", Bytecodes::name(c),
1627 bcp, cp_index, new_index));
1628 // Rewriter::rewrite_method() uses put_native_u2() in this
1629 // situation because it is reusing the constant pool index
1630 // location for a native index into the constantPoolCache.
1631 // Since we are updating the constant pool index prior to
1632 // verification and constantPoolCache initialization, we
1633 // need to keep the new index in Java byte order.
1634 Bytes::put_Java_u2(p, new_index);
1635 }
1636 } break;
1637 }
1638 } // end for each bytecode
1639 } // end rewrite_cp_refs_in_method()
1642 // Rewrite constant pool references in the class_annotations field.
1643 bool VM_RedefineClasses::rewrite_cp_refs_in_class_annotations(
1644 instanceKlassHandle scratch_class, TRAPS) {
1646 AnnotationArray* class_annotations = scratch_class->class_annotations();
1647 if (class_annotations == NULL || class_annotations->length() == 0) {
1648 // no class_annotations so nothing to do
1649 return true;
1650 }
1652 RC_TRACE_WITH_THREAD(0x02000000, THREAD,
1653 ("class_annotations length=%d", class_annotations->length()));
1655 int byte_i = 0; // byte index into class_annotations
1656 return rewrite_cp_refs_in_annotations_typeArray(class_annotations, byte_i,
1657 THREAD);
1658 }
1661 // Rewrite constant pool references in an annotations typeArray. This
1662 // "structure" is adapted from the RuntimeVisibleAnnotations_attribute
1663 // that is described in section 4.8.15 of the 2nd-edition of the VM spec:
1664 //
1665 // annotations_typeArray {
1666 // u2 num_annotations;
1667 // annotation annotations[num_annotations];
1668 // }
1669 //
1670 bool VM_RedefineClasses::rewrite_cp_refs_in_annotations_typeArray(
1671 AnnotationArray* annotations_typeArray, int &byte_i_ref, TRAPS) {
1673 if ((byte_i_ref + 2) > annotations_typeArray->length()) {
1674 // not enough room for num_annotations field
1675 RC_TRACE_WITH_THREAD(0x02000000, THREAD,
1676 ("length() is too small for num_annotations field"));
1677 return false;
1678 }
1680 u2 num_annotations = Bytes::get_Java_u2((address)
1681 annotations_typeArray->adr_at(byte_i_ref));
1682 byte_i_ref += 2;
1684 RC_TRACE_WITH_THREAD(0x02000000, THREAD,
1685 ("num_annotations=%d", num_annotations));
1687 int calc_num_annotations = 0;
1688 for (; calc_num_annotations < num_annotations; calc_num_annotations++) {
1689 if (!rewrite_cp_refs_in_annotation_struct(annotations_typeArray,
1690 byte_i_ref, THREAD)) {
1691 RC_TRACE_WITH_THREAD(0x02000000, THREAD,
1692 ("bad annotation_struct at %d", calc_num_annotations));
1693 // propagate failure back to caller
1694 return false;
1695 }
1696 }
1697 assert(num_annotations == calc_num_annotations, "sanity check");
1699 return true;
1700 } // end rewrite_cp_refs_in_annotations_typeArray()
1703 // Rewrite constant pool references in the annotation struct portion of
1704 // an annotations_typeArray. This "structure" is from section 4.8.15 of
1705 // the 2nd-edition of the VM spec:
1706 //
1707 // struct annotation {
1708 // u2 type_index;
1709 // u2 num_element_value_pairs;
1710 // {
1711 // u2 element_name_index;
1712 // element_value value;
1713 // } element_value_pairs[num_element_value_pairs];
1714 // }
1715 //
1716 bool VM_RedefineClasses::rewrite_cp_refs_in_annotation_struct(
1717 AnnotationArray* annotations_typeArray, int &byte_i_ref, TRAPS) {
1718 if ((byte_i_ref + 2 + 2) > annotations_typeArray->length()) {
1719 // not enough room for smallest annotation_struct
1720 RC_TRACE_WITH_THREAD(0x02000000, THREAD,
1721 ("length() is too small for annotation_struct"));
1722 return false;
1723 }
1725 u2 type_index = rewrite_cp_ref_in_annotation_data(annotations_typeArray,
1726 byte_i_ref, "mapped old type_index=%d", THREAD);
1728 u2 num_element_value_pairs = Bytes::get_Java_u2((address)
1729 annotations_typeArray->adr_at(byte_i_ref));
1730 byte_i_ref += 2;
1732 RC_TRACE_WITH_THREAD(0x02000000, THREAD,
1733 ("type_index=%d num_element_value_pairs=%d", type_index,
1734 num_element_value_pairs));
1736 int calc_num_element_value_pairs = 0;
1737 for (; calc_num_element_value_pairs < num_element_value_pairs;
1738 calc_num_element_value_pairs++) {
1739 if ((byte_i_ref + 2) > annotations_typeArray->length()) {
1740 // not enough room for another element_name_index, let alone
1741 // the rest of another component
1742 RC_TRACE_WITH_THREAD(0x02000000, THREAD,
1743 ("length() is too small for element_name_index"));
1744 return false;
1745 }
1747 u2 element_name_index = rewrite_cp_ref_in_annotation_data(
1748 annotations_typeArray, byte_i_ref,
1749 "mapped old element_name_index=%d", THREAD);
1751 RC_TRACE_WITH_THREAD(0x02000000, THREAD,
1752 ("element_name_index=%d", element_name_index));
1754 if (!rewrite_cp_refs_in_element_value(annotations_typeArray,
1755 byte_i_ref, THREAD)) {
1756 RC_TRACE_WITH_THREAD(0x02000000, THREAD,
1757 ("bad element_value at %d", calc_num_element_value_pairs));
1758 // propagate failure back to caller
1759 return false;
1760 }
1761 } // end for each component
1762 assert(num_element_value_pairs == calc_num_element_value_pairs,
1763 "sanity check");
1765 return true;
1766 } // end rewrite_cp_refs_in_annotation_struct()
1769 // Rewrite a constant pool reference at the current position in
1770 // annotations_typeArray if needed. Returns the original constant
1771 // pool reference if a rewrite was not needed or the new constant
1772 // pool reference if a rewrite was needed.
1773 u2 VM_RedefineClasses::rewrite_cp_ref_in_annotation_data(
1774 AnnotationArray* annotations_typeArray, int &byte_i_ref,
1775 const char * trace_mesg, TRAPS) {
1777 address cp_index_addr = (address)
1778 annotations_typeArray->adr_at(byte_i_ref);
1779 u2 old_cp_index = Bytes::get_Java_u2(cp_index_addr);
1780 u2 new_cp_index = find_new_index(old_cp_index);
1781 if (new_cp_index != 0) {
1782 RC_TRACE_WITH_THREAD(0x02000000, THREAD, (trace_mesg, old_cp_index));
1783 Bytes::put_Java_u2(cp_index_addr, new_cp_index);
1784 old_cp_index = new_cp_index;
1785 }
1786 byte_i_ref += 2;
1787 return old_cp_index;
1788 }
1791 // Rewrite constant pool references in the element_value portion of an
1792 // annotations_typeArray. This "structure" is from section 4.8.15.1 of
1793 // the 2nd-edition of the VM spec:
1794 //
1795 // struct element_value {
1796 // u1 tag;
1797 // union {
1798 // u2 const_value_index;
1799 // {
1800 // u2 type_name_index;
1801 // u2 const_name_index;
1802 // } enum_const_value;
1803 // u2 class_info_index;
1804 // annotation annotation_value;
1805 // struct {
1806 // u2 num_values;
1807 // element_value values[num_values];
1808 // } array_value;
1809 // } value;
1810 // }
1811 //
1812 bool VM_RedefineClasses::rewrite_cp_refs_in_element_value(
1813 AnnotationArray* annotations_typeArray, int &byte_i_ref, TRAPS) {
1815 if ((byte_i_ref + 1) > annotations_typeArray->length()) {
1816 // not enough room for a tag let alone the rest of an element_value
1817 RC_TRACE_WITH_THREAD(0x02000000, THREAD,
1818 ("length() is too small for a tag"));
1819 return false;
1820 }
1822 u1 tag = annotations_typeArray->at(byte_i_ref);
1823 byte_i_ref++;
1824 RC_TRACE_WITH_THREAD(0x02000000, THREAD, ("tag='%c'", tag));
1826 switch (tag) {
1827 // These BaseType tag values are from Table 4.2 in VM spec:
1828 case 'B': // byte
1829 case 'C': // char
1830 case 'D': // double
1831 case 'F': // float
1832 case 'I': // int
1833 case 'J': // long
1834 case 'S': // short
1835 case 'Z': // boolean
1837 // The remaining tag values are from Table 4.8 in the 2nd-edition of
1838 // the VM spec:
1839 case 's':
1840 {
1841 // For the above tag values (including the BaseType values),
1842 // value.const_value_index is right union field.
1844 if ((byte_i_ref + 2) > annotations_typeArray->length()) {
1845 // not enough room for a const_value_index
1846 RC_TRACE_WITH_THREAD(0x02000000, THREAD,
1847 ("length() is too small for a const_value_index"));
1848 return false;
1849 }
1851 u2 const_value_index = rewrite_cp_ref_in_annotation_data(
1852 annotations_typeArray, byte_i_ref,
1853 "mapped old const_value_index=%d", THREAD);
1855 RC_TRACE_WITH_THREAD(0x02000000, THREAD,
1856 ("const_value_index=%d", const_value_index));
1857 } break;
1859 case 'e':
1860 {
1861 // for the above tag value, value.enum_const_value is right union field
1863 if ((byte_i_ref + 4) > annotations_typeArray->length()) {
1864 // not enough room for a enum_const_value
1865 RC_TRACE_WITH_THREAD(0x02000000, THREAD,
1866 ("length() is too small for a enum_const_value"));
1867 return false;
1868 }
1870 u2 type_name_index = rewrite_cp_ref_in_annotation_data(
1871 annotations_typeArray, byte_i_ref,
1872 "mapped old type_name_index=%d", THREAD);
1874 u2 const_name_index = rewrite_cp_ref_in_annotation_data(
1875 annotations_typeArray, byte_i_ref,
1876 "mapped old const_name_index=%d", THREAD);
1878 RC_TRACE_WITH_THREAD(0x02000000, THREAD,
1879 ("type_name_index=%d const_name_index=%d", type_name_index,
1880 const_name_index));
1881 } break;
1883 case 'c':
1884 {
1885 // for the above tag value, value.class_info_index is right union field
1887 if ((byte_i_ref + 2) > annotations_typeArray->length()) {
1888 // not enough room for a class_info_index
1889 RC_TRACE_WITH_THREAD(0x02000000, THREAD,
1890 ("length() is too small for a class_info_index"));
1891 return false;
1892 }
1894 u2 class_info_index = rewrite_cp_ref_in_annotation_data(
1895 annotations_typeArray, byte_i_ref,
1896 "mapped old class_info_index=%d", THREAD);
1898 RC_TRACE_WITH_THREAD(0x02000000, THREAD,
1899 ("class_info_index=%d", class_info_index));
1900 } break;
1902 case '@':
1903 // For the above tag value, value.attr_value is the right union
1904 // field. This is a nested annotation.
1905 if (!rewrite_cp_refs_in_annotation_struct(annotations_typeArray,
1906 byte_i_ref, THREAD)) {
1907 // propagate failure back to caller
1908 return false;
1909 }
1910 break;
1912 case '[':
1913 {
1914 if ((byte_i_ref + 2) > annotations_typeArray->length()) {
1915 // not enough room for a num_values field
1916 RC_TRACE_WITH_THREAD(0x02000000, THREAD,
1917 ("length() is too small for a num_values field"));
1918 return false;
1919 }
1921 // For the above tag value, value.array_value is the right union
1922 // field. This is an array of nested element_value.
1923 u2 num_values = Bytes::get_Java_u2((address)
1924 annotations_typeArray->adr_at(byte_i_ref));
1925 byte_i_ref += 2;
1926 RC_TRACE_WITH_THREAD(0x02000000, THREAD, ("num_values=%d", num_values));
1928 int calc_num_values = 0;
1929 for (; calc_num_values < num_values; calc_num_values++) {
1930 if (!rewrite_cp_refs_in_element_value(
1931 annotations_typeArray, byte_i_ref, THREAD)) {
1932 RC_TRACE_WITH_THREAD(0x02000000, THREAD,
1933 ("bad nested element_value at %d", calc_num_values));
1934 // propagate failure back to caller
1935 return false;
1936 }
1937 }
1938 assert(num_values == calc_num_values, "sanity check");
1939 } break;
1941 default:
1942 RC_TRACE_WITH_THREAD(0x02000000, THREAD, ("bad tag=0x%x", tag));
1943 return false;
1944 } // end decode tag field
1946 return true;
1947 } // end rewrite_cp_refs_in_element_value()
1950 // Rewrite constant pool references in a fields_annotations field.
1951 bool VM_RedefineClasses::rewrite_cp_refs_in_fields_annotations(
1952 instanceKlassHandle scratch_class, TRAPS) {
1954 Annotations* sca = scratch_class->annotations();
1955 if (sca == NULL) return true;
1957 Array<AnnotationArray*>* fields_annotations = sca->fields_annotations();
1959 if (fields_annotations == NULL || fields_annotations->length() == 0) {
1960 // no fields_annotations so nothing to do
1961 return true;
1962 }
1964 RC_TRACE_WITH_THREAD(0x02000000, THREAD,
1965 ("fields_annotations length=%d", fields_annotations->length()));
1967 for (int i = 0; i < fields_annotations->length(); i++) {
1968 AnnotationArray* field_annotations = fields_annotations->at(i);
1969 if (field_annotations == NULL || field_annotations->length() == 0) {
1970 // this field does not have any annotations so skip it
1971 continue;
1972 }
1974 int byte_i = 0; // byte index into field_annotations
1975 if (!rewrite_cp_refs_in_annotations_typeArray(field_annotations, byte_i,
1976 THREAD)) {
1977 RC_TRACE_WITH_THREAD(0x02000000, THREAD,
1978 ("bad field_annotations at %d", i));
1979 // propagate failure back to caller
1980 return false;
1981 }
1982 }
1984 return true;
1985 } // end rewrite_cp_refs_in_fields_annotations()
1988 // Rewrite constant pool references in a methods_annotations field.
1989 bool VM_RedefineClasses::rewrite_cp_refs_in_methods_annotations(
1990 instanceKlassHandle scratch_class, TRAPS) {
1992 Annotations* sca = scratch_class->annotations();
1993 if (sca == NULL) return true;
1995 Array<AnnotationArray*>* methods_annotations = sca->methods_annotations();
1997 if (methods_annotations == NULL || methods_annotations->length() == 0) {
1998 // no methods_annotations so nothing to do
1999 return true;
2000 }
2002 RC_TRACE_WITH_THREAD(0x02000000, THREAD,
2003 ("methods_annotations length=%d", methods_annotations->length()));
2005 for (int i = 0; i < methods_annotations->length(); i++) {
2006 AnnotationArray* method_annotations = methods_annotations->at(i);
2007 if (method_annotations == NULL || method_annotations->length() == 0) {
2008 // this method does not have any annotations so skip it
2009 continue;
2010 }
2012 int byte_i = 0; // byte index into method_annotations
2013 if (!rewrite_cp_refs_in_annotations_typeArray(method_annotations, byte_i,
2014 THREAD)) {
2015 RC_TRACE_WITH_THREAD(0x02000000, THREAD,
2016 ("bad method_annotations at %d", i));
2017 // propagate failure back to caller
2018 return false;
2019 }
2020 }
2022 return true;
2023 } // end rewrite_cp_refs_in_methods_annotations()
2026 // Rewrite constant pool references in a methods_parameter_annotations
2027 // field. This "structure" is adapted from the
2028 // RuntimeVisibleParameterAnnotations_attribute described in section
2029 // 4.8.17 of the 2nd-edition of the VM spec:
2030 //
2031 // methods_parameter_annotations_typeArray {
2032 // u1 num_parameters;
2033 // {
2034 // u2 num_annotations;
2035 // annotation annotations[num_annotations];
2036 // } parameter_annotations[num_parameters];
2037 // }
2038 //
2039 bool VM_RedefineClasses::rewrite_cp_refs_in_methods_parameter_annotations(
2040 instanceKlassHandle scratch_class, TRAPS) {
2042 Annotations* sca = scratch_class->annotations();
2043 if (sca == NULL) return true;
2045 Array<AnnotationArray*>* methods_parameter_annotations =
2046 sca->methods_parameter_annotations();
2048 if (methods_parameter_annotations == NULL
2049 || methods_parameter_annotations->length() == 0) {
2050 // no methods_parameter_annotations so nothing to do
2051 return true;
2052 }
2054 RC_TRACE_WITH_THREAD(0x02000000, THREAD,
2055 ("methods_parameter_annotations length=%d",
2056 methods_parameter_annotations->length()));
2058 for (int i = 0; i < methods_parameter_annotations->length(); i++) {
2059 AnnotationArray* method_parameter_annotations = methods_parameter_annotations->at(i);
2060 if (method_parameter_annotations == NULL
2061 || method_parameter_annotations->length() == 0) {
2062 // this method does not have any parameter annotations so skip it
2063 continue;
2064 }
2066 if (method_parameter_annotations->length() < 1) {
2067 // not enough room for a num_parameters field
2068 RC_TRACE_WITH_THREAD(0x02000000, THREAD,
2069 ("length() is too small for a num_parameters field at %d", i));
2070 return false;
2071 }
2073 int byte_i = 0; // byte index into method_parameter_annotations
2075 u1 num_parameters = method_parameter_annotations->at(byte_i);
2076 byte_i++;
2078 RC_TRACE_WITH_THREAD(0x02000000, THREAD,
2079 ("num_parameters=%d", num_parameters));
2081 int calc_num_parameters = 0;
2082 for (; calc_num_parameters < num_parameters; calc_num_parameters++) {
2083 if (!rewrite_cp_refs_in_annotations_typeArray(
2084 method_parameter_annotations, byte_i, THREAD)) {
2085 RC_TRACE_WITH_THREAD(0x02000000, THREAD,
2086 ("bad method_parameter_annotations at %d", calc_num_parameters));
2087 // propagate failure back to caller
2088 return false;
2089 }
2090 }
2091 assert(num_parameters == calc_num_parameters, "sanity check");
2092 }
2094 return true;
2095 } // end rewrite_cp_refs_in_methods_parameter_annotations()
2098 // Rewrite constant pool references in a methods_default_annotations
2099 // field. This "structure" is adapted from the AnnotationDefault_attribute
2100 // that is described in section 4.8.19 of the 2nd-edition of the VM spec:
2101 //
2102 // methods_default_annotations_typeArray {
2103 // element_value default_value;
2104 // }
2105 //
2106 bool VM_RedefineClasses::rewrite_cp_refs_in_methods_default_annotations(
2107 instanceKlassHandle scratch_class, TRAPS) {
2109 Annotations* sca = scratch_class->annotations();
2110 if (sca == NULL) return true;
2112 Array<AnnotationArray*>* methods_default_annotations =
2113 sca->methods_default_annotations();
2115 if (methods_default_annotations == NULL
2116 || methods_default_annotations->length() == 0) {
2117 // no methods_default_annotations so nothing to do
2118 return true;
2119 }
2121 RC_TRACE_WITH_THREAD(0x02000000, THREAD,
2122 ("methods_default_annotations length=%d",
2123 methods_default_annotations->length()));
2125 for (int i = 0; i < methods_default_annotations->length(); i++) {
2126 AnnotationArray* method_default_annotations = methods_default_annotations->at(i);
2127 if (method_default_annotations == NULL
2128 || method_default_annotations->length() == 0) {
2129 // this method does not have any default annotations so skip it
2130 continue;
2131 }
2133 int byte_i = 0; // byte index into method_default_annotations
2135 if (!rewrite_cp_refs_in_element_value(
2136 method_default_annotations, byte_i, THREAD)) {
2137 RC_TRACE_WITH_THREAD(0x02000000, THREAD,
2138 ("bad default element_value at %d", i));
2139 // propagate failure back to caller
2140 return false;
2141 }
2142 }
2144 return true;
2145 } // end rewrite_cp_refs_in_methods_default_annotations()
2148 // Rewrite constant pool references in the method's stackmap table.
2149 // These "structures" are adapted from the StackMapTable_attribute that
2150 // is described in section 4.8.4 of the 6.0 version of the VM spec
2151 // (dated 2005.10.26):
2152 // file:///net/quincunx.sfbay/export/gbracha/ClassFile-Java6.pdf
2153 //
2154 // stack_map {
2155 // u2 number_of_entries;
2156 // stack_map_frame entries[number_of_entries];
2157 // }
2158 //
2159 void VM_RedefineClasses::rewrite_cp_refs_in_stack_map_table(
2160 methodHandle method, TRAPS) {
2162 if (!method->has_stackmap_table()) {
2163 return;
2164 }
2166 AnnotationArray* stackmap_data = method->stackmap_data();
2167 address stackmap_p = (address)stackmap_data->adr_at(0);
2168 address stackmap_end = stackmap_p + stackmap_data->length();
2170 assert(stackmap_p + 2 <= stackmap_end, "no room for number_of_entries");
2171 u2 number_of_entries = Bytes::get_Java_u2(stackmap_p);
2172 stackmap_p += 2;
2174 RC_TRACE_WITH_THREAD(0x04000000, THREAD,
2175 ("number_of_entries=%u", number_of_entries));
2177 // walk through each stack_map_frame
2178 u2 calc_number_of_entries = 0;
2179 for (; calc_number_of_entries < number_of_entries; calc_number_of_entries++) {
2180 // The stack_map_frame structure is a u1 frame_type followed by
2181 // 0 or more bytes of data:
2182 //
2183 // union stack_map_frame {
2184 // same_frame;
2185 // same_locals_1_stack_item_frame;
2186 // same_locals_1_stack_item_frame_extended;
2187 // chop_frame;
2188 // same_frame_extended;
2189 // append_frame;
2190 // full_frame;
2191 // }
2193 assert(stackmap_p + 1 <= stackmap_end, "no room for frame_type");
2194 // The Linux compiler does not like frame_type to be u1 or u2. It
2195 // issues the following warning for the first if-statement below:
2196 //
2197 // "warning: comparison is always true due to limited range of data type"
2198 //
2199 u4 frame_type = *stackmap_p;
2200 stackmap_p++;
2202 // same_frame {
2203 // u1 frame_type = SAME; /* 0-63 */
2204 // }
2205 if (frame_type >= 0 && frame_type <= 63) {
2206 // nothing more to do for same_frame
2207 }
2209 // same_locals_1_stack_item_frame {
2210 // u1 frame_type = SAME_LOCALS_1_STACK_ITEM; /* 64-127 */
2211 // verification_type_info stack[1];
2212 // }
2213 else if (frame_type >= 64 && frame_type <= 127) {
2214 rewrite_cp_refs_in_verification_type_info(stackmap_p, stackmap_end,
2215 calc_number_of_entries, frame_type, THREAD);
2216 }
2218 // reserved for future use
2219 else if (frame_type >= 128 && frame_type <= 246) {
2220 // nothing more to do for reserved frame_types
2221 }
2223 // same_locals_1_stack_item_frame_extended {
2224 // u1 frame_type = SAME_LOCALS_1_STACK_ITEM_EXTENDED; /* 247 */
2225 // u2 offset_delta;
2226 // verification_type_info stack[1];
2227 // }
2228 else if (frame_type == 247) {
2229 stackmap_p += 2;
2230 rewrite_cp_refs_in_verification_type_info(stackmap_p, stackmap_end,
2231 calc_number_of_entries, frame_type, THREAD);
2232 }
2234 // chop_frame {
2235 // u1 frame_type = CHOP; /* 248-250 */
2236 // u2 offset_delta;
2237 // }
2238 else if (frame_type >= 248 && frame_type <= 250) {
2239 stackmap_p += 2;
2240 }
2242 // same_frame_extended {
2243 // u1 frame_type = SAME_FRAME_EXTENDED; /* 251*/
2244 // u2 offset_delta;
2245 // }
2246 else if (frame_type == 251) {
2247 stackmap_p += 2;
2248 }
2250 // append_frame {
2251 // u1 frame_type = APPEND; /* 252-254 */
2252 // u2 offset_delta;
2253 // verification_type_info locals[frame_type - 251];
2254 // }
2255 else if (frame_type >= 252 && frame_type <= 254) {
2256 assert(stackmap_p + 2 <= stackmap_end,
2257 "no room for offset_delta");
2258 stackmap_p += 2;
2259 u1 len = frame_type - 251;
2260 for (u1 i = 0; i < len; i++) {
2261 rewrite_cp_refs_in_verification_type_info(stackmap_p, stackmap_end,
2262 calc_number_of_entries, frame_type, THREAD);
2263 }
2264 }
2266 // full_frame {
2267 // u1 frame_type = FULL_FRAME; /* 255 */
2268 // u2 offset_delta;
2269 // u2 number_of_locals;
2270 // verification_type_info locals[number_of_locals];
2271 // u2 number_of_stack_items;
2272 // verification_type_info stack[number_of_stack_items];
2273 // }
2274 else if (frame_type == 255) {
2275 assert(stackmap_p + 2 + 2 <= stackmap_end,
2276 "no room for smallest full_frame");
2277 stackmap_p += 2;
2279 u2 number_of_locals = Bytes::get_Java_u2(stackmap_p);
2280 stackmap_p += 2;
2282 for (u2 locals_i = 0; locals_i < number_of_locals; locals_i++) {
2283 rewrite_cp_refs_in_verification_type_info(stackmap_p, stackmap_end,
2284 calc_number_of_entries, frame_type, THREAD);
2285 }
2287 // Use the largest size for the number_of_stack_items, but only get
2288 // the right number of bytes.
2289 u2 number_of_stack_items = Bytes::get_Java_u2(stackmap_p);
2290 stackmap_p += 2;
2292 for (u2 stack_i = 0; stack_i < number_of_stack_items; stack_i++) {
2293 rewrite_cp_refs_in_verification_type_info(stackmap_p, stackmap_end,
2294 calc_number_of_entries, frame_type, THREAD);
2295 }
2296 }
2297 } // end while there is a stack_map_frame
2298 assert(number_of_entries == calc_number_of_entries, "sanity check");
2299 } // end rewrite_cp_refs_in_stack_map_table()
2302 // Rewrite constant pool references in the verification type info
2303 // portion of the method's stackmap table. These "structures" are
2304 // adapted from the StackMapTable_attribute that is described in
2305 // section 4.8.4 of the 6.0 version of the VM spec (dated 2005.10.26):
2306 // file:///net/quincunx.sfbay/export/gbracha/ClassFile-Java6.pdf
2307 //
2308 // The verification_type_info structure is a u1 tag followed by 0 or
2309 // more bytes of data:
2310 //
2311 // union verification_type_info {
2312 // Top_variable_info;
2313 // Integer_variable_info;
2314 // Float_variable_info;
2315 // Long_variable_info;
2316 // Double_variable_info;
2317 // Null_variable_info;
2318 // UninitializedThis_variable_info;
2319 // Object_variable_info;
2320 // Uninitialized_variable_info;
2321 // }
2322 //
2323 void VM_RedefineClasses::rewrite_cp_refs_in_verification_type_info(
2324 address& stackmap_p_ref, address stackmap_end, u2 frame_i,
2325 u1 frame_type, TRAPS) {
2327 assert(stackmap_p_ref + 1 <= stackmap_end, "no room for tag");
2328 u1 tag = *stackmap_p_ref;
2329 stackmap_p_ref++;
2331 switch (tag) {
2332 // Top_variable_info {
2333 // u1 tag = ITEM_Top; /* 0 */
2334 // }
2335 // verificationType.hpp has zero as ITEM_Bogus instead of ITEM_Top
2336 case 0: // fall through
2338 // Integer_variable_info {
2339 // u1 tag = ITEM_Integer; /* 1 */
2340 // }
2341 case ITEM_Integer: // fall through
2343 // Float_variable_info {
2344 // u1 tag = ITEM_Float; /* 2 */
2345 // }
2346 case ITEM_Float: // fall through
2348 // Double_variable_info {
2349 // u1 tag = ITEM_Double; /* 3 */
2350 // }
2351 case ITEM_Double: // fall through
2353 // Long_variable_info {
2354 // u1 tag = ITEM_Long; /* 4 */
2355 // }
2356 case ITEM_Long: // fall through
2358 // Null_variable_info {
2359 // u1 tag = ITEM_Null; /* 5 */
2360 // }
2361 case ITEM_Null: // fall through
2363 // UninitializedThis_variable_info {
2364 // u1 tag = ITEM_UninitializedThis; /* 6 */
2365 // }
2366 case ITEM_UninitializedThis:
2367 // nothing more to do for the above tag types
2368 break;
2370 // Object_variable_info {
2371 // u1 tag = ITEM_Object; /* 7 */
2372 // u2 cpool_index;
2373 // }
2374 case ITEM_Object:
2375 {
2376 assert(stackmap_p_ref + 2 <= stackmap_end, "no room for cpool_index");
2377 u2 cpool_index = Bytes::get_Java_u2(stackmap_p_ref);
2378 u2 new_cp_index = find_new_index(cpool_index);
2379 if (new_cp_index != 0) {
2380 RC_TRACE_WITH_THREAD(0x04000000, THREAD,
2381 ("mapped old cpool_index=%d", cpool_index));
2382 Bytes::put_Java_u2(stackmap_p_ref, new_cp_index);
2383 cpool_index = new_cp_index;
2384 }
2385 stackmap_p_ref += 2;
2387 RC_TRACE_WITH_THREAD(0x04000000, THREAD,
2388 ("frame_i=%u, frame_type=%u, cpool_index=%d", frame_i,
2389 frame_type, cpool_index));
2390 } break;
2392 // Uninitialized_variable_info {
2393 // u1 tag = ITEM_Uninitialized; /* 8 */
2394 // u2 offset;
2395 // }
2396 case ITEM_Uninitialized:
2397 assert(stackmap_p_ref + 2 <= stackmap_end, "no room for offset");
2398 stackmap_p_ref += 2;
2399 break;
2401 default:
2402 RC_TRACE_WITH_THREAD(0x04000000, THREAD,
2403 ("frame_i=%u, frame_type=%u, bad tag=0x%x", frame_i, frame_type, tag));
2404 ShouldNotReachHere();
2405 break;
2406 } // end switch (tag)
2407 } // end rewrite_cp_refs_in_verification_type_info()
2410 // Change the constant pool associated with klass scratch_class to
2411 // scratch_cp. If shrink is true, then scratch_cp_length elements
2412 // are copied from scratch_cp to a smaller constant pool and the
2413 // smaller constant pool is associated with scratch_class.
2414 void VM_RedefineClasses::set_new_constant_pool(
2415 ClassLoaderData* loader_data,
2416 instanceKlassHandle scratch_class, constantPoolHandle scratch_cp,
2417 int scratch_cp_length, TRAPS) {
2418 assert(scratch_cp->length() >= scratch_cp_length, "sanity check");
2420 // scratch_cp is a merged constant pool and has enough space for a
2421 // worst case merge situation. We want to associate the minimum
2422 // sized constant pool with the klass to save space.
2423 constantPoolHandle smaller_cp(THREAD,
2424 ConstantPool::allocate(loader_data, scratch_cp_length,
2425 THREAD));
2426 // preserve orig_length() value in the smaller copy
2427 int orig_length = scratch_cp->orig_length();
2428 assert(orig_length != 0, "sanity check");
2429 smaller_cp->set_orig_length(orig_length);
2430 scratch_cp->copy_cp_to(1, scratch_cp_length - 1, smaller_cp, 1, THREAD);
2431 scratch_cp = smaller_cp;
2433 // attach new constant pool to klass
2434 scratch_cp->set_pool_holder(scratch_class());
2436 // attach klass to new constant pool
2437 scratch_class->set_constants(scratch_cp());
2439 int i; // for portability
2441 // update each field in klass to use new constant pool indices as needed
2442 for (JavaFieldStream fs(scratch_class); !fs.done(); fs.next()) {
2443 jshort cur_index = fs.name_index();
2444 jshort new_index = find_new_index(cur_index);
2445 if (new_index != 0) {
2446 RC_TRACE_WITH_THREAD(0x00080000, THREAD,
2447 ("field-name_index change: %d to %d", cur_index, new_index));
2448 fs.set_name_index(new_index);
2449 }
2450 cur_index = fs.signature_index();
2451 new_index = find_new_index(cur_index);
2452 if (new_index != 0) {
2453 RC_TRACE_WITH_THREAD(0x00080000, THREAD,
2454 ("field-signature_index change: %d to %d", cur_index, new_index));
2455 fs.set_signature_index(new_index);
2456 }
2457 cur_index = fs.initval_index();
2458 new_index = find_new_index(cur_index);
2459 if (new_index != 0) {
2460 RC_TRACE_WITH_THREAD(0x00080000, THREAD,
2461 ("field-initval_index change: %d to %d", cur_index, new_index));
2462 fs.set_initval_index(new_index);
2463 }
2464 cur_index = fs.generic_signature_index();
2465 new_index = find_new_index(cur_index);
2466 if (new_index != 0) {
2467 RC_TRACE_WITH_THREAD(0x00080000, THREAD,
2468 ("field-generic_signature change: %d to %d", cur_index, new_index));
2469 fs.set_generic_signature_index(new_index);
2470 }
2471 } // end for each field
2473 // Update constant pool indices in the inner classes info to use
2474 // new constant indices as needed. The inner classes info is a
2475 // quadruple:
2476 // (inner_class_info, outer_class_info, inner_name, inner_access_flags)
2477 InnerClassesIterator iter(scratch_class);
2478 for (; !iter.done(); iter.next()) {
2479 int cur_index = iter.inner_class_info_index();
2480 if (cur_index == 0) {
2481 continue; // JVM spec. allows null inner class refs so skip it
2482 }
2483 int new_index = find_new_index(cur_index);
2484 if (new_index != 0) {
2485 RC_TRACE_WITH_THREAD(0x00080000, THREAD,
2486 ("inner_class_info change: %d to %d", cur_index, new_index));
2487 iter.set_inner_class_info_index(new_index);
2488 }
2489 cur_index = iter.outer_class_info_index();
2490 new_index = find_new_index(cur_index);
2491 if (new_index != 0) {
2492 RC_TRACE_WITH_THREAD(0x00080000, THREAD,
2493 ("outer_class_info change: %d to %d", cur_index, new_index));
2494 iter.set_outer_class_info_index(new_index);
2495 }
2496 cur_index = iter.inner_name_index();
2497 new_index = find_new_index(cur_index);
2498 if (new_index != 0) {
2499 RC_TRACE_WITH_THREAD(0x00080000, THREAD,
2500 ("inner_name change: %d to %d", cur_index, new_index));
2501 iter.set_inner_name_index(new_index);
2502 }
2503 } // end for each inner class
2505 // Attach each method in klass to the new constant pool and update
2506 // to use new constant pool indices as needed:
2507 Array<Method*>* methods = scratch_class->methods();
2508 for (i = methods->length() - 1; i >= 0; i--) {
2509 methodHandle method(THREAD, methods->at(i));
2510 method->set_constants(scratch_cp());
2512 int new_index = find_new_index(method->name_index());
2513 if (new_index != 0) {
2514 RC_TRACE_WITH_THREAD(0x00080000, THREAD,
2515 ("method-name_index change: %d to %d", method->name_index(),
2516 new_index));
2517 method->set_name_index(new_index);
2518 }
2519 new_index = find_new_index(method->signature_index());
2520 if (new_index != 0) {
2521 RC_TRACE_WITH_THREAD(0x00080000, THREAD,
2522 ("method-signature_index change: %d to %d",
2523 method->signature_index(), new_index));
2524 method->set_signature_index(new_index);
2525 }
2526 new_index = find_new_index(method->generic_signature_index());
2527 if (new_index != 0) {
2528 RC_TRACE_WITH_THREAD(0x00080000, THREAD,
2529 ("method-generic_signature_index change: %d to %d",
2530 method->generic_signature_index(), new_index));
2531 method->set_generic_signature_index(new_index);
2532 }
2534 // Update constant pool indices in the method's checked exception
2535 // table to use new constant indices as needed.
2536 int cext_length = method->checked_exceptions_length();
2537 if (cext_length > 0) {
2538 CheckedExceptionElement * cext_table =
2539 method->checked_exceptions_start();
2540 for (int j = 0; j < cext_length; j++) {
2541 int cur_index = cext_table[j].class_cp_index;
2542 int new_index = find_new_index(cur_index);
2543 if (new_index != 0) {
2544 RC_TRACE_WITH_THREAD(0x00080000, THREAD,
2545 ("cext-class_cp_index change: %d to %d", cur_index, new_index));
2546 cext_table[j].class_cp_index = (u2)new_index;
2547 }
2548 } // end for each checked exception table entry
2549 } // end if there are checked exception table entries
2551 // Update each catch type index in the method's exception table
2552 // to use new constant pool indices as needed. The exception table
2553 // holds quadruple entries of the form:
2554 // (beg_bci, end_bci, handler_bci, klass_index)
2556 ExceptionTable ex_table(method());
2557 int ext_length = ex_table.length();
2559 for (int j = 0; j < ext_length; j ++) {
2560 int cur_index = ex_table.catch_type_index(j);
2561 int new_index = find_new_index(cur_index);
2562 if (new_index != 0) {
2563 RC_TRACE_WITH_THREAD(0x00080000, THREAD,
2564 ("ext-klass_index change: %d to %d", cur_index, new_index));
2565 ex_table.set_catch_type_index(j, new_index);
2566 }
2567 } // end for each exception table entry
2569 // Update constant pool indices in the method's local variable
2570 // table to use new constant indices as needed. The local variable
2571 // table hold sextuple entries of the form:
2572 // (start_pc, length, name_index, descriptor_index, signature_index, slot)
2573 int lvt_length = method->localvariable_table_length();
2574 if (lvt_length > 0) {
2575 LocalVariableTableElement * lv_table =
2576 method->localvariable_table_start();
2577 for (int j = 0; j < lvt_length; j++) {
2578 int cur_index = lv_table[j].name_cp_index;
2579 int new_index = find_new_index(cur_index);
2580 if (new_index != 0) {
2581 RC_TRACE_WITH_THREAD(0x00080000, THREAD,
2582 ("lvt-name_cp_index change: %d to %d", cur_index, new_index));
2583 lv_table[j].name_cp_index = (u2)new_index;
2584 }
2585 cur_index = lv_table[j].descriptor_cp_index;
2586 new_index = find_new_index(cur_index);
2587 if (new_index != 0) {
2588 RC_TRACE_WITH_THREAD(0x00080000, THREAD,
2589 ("lvt-descriptor_cp_index change: %d to %d", cur_index,
2590 new_index));
2591 lv_table[j].descriptor_cp_index = (u2)new_index;
2592 }
2593 cur_index = lv_table[j].signature_cp_index;
2594 new_index = find_new_index(cur_index);
2595 if (new_index != 0) {
2596 RC_TRACE_WITH_THREAD(0x00080000, THREAD,
2597 ("lvt-signature_cp_index change: %d to %d", cur_index, new_index));
2598 lv_table[j].signature_cp_index = (u2)new_index;
2599 }
2600 } // end for each local variable table entry
2601 } // end if there are local variable table entries
2603 rewrite_cp_refs_in_stack_map_table(method, THREAD);
2604 } // end for each method
2605 } // end set_new_constant_pool()
2608 void VM_RedefineClasses::adjust_array_vtable(Klass* k_oop) {
2609 ArrayKlass* ak = ArrayKlass::cast(k_oop);
2610 bool trace_name_printed = false;
2611 ak->vtable()->adjust_method_entries(_matching_old_methods,
2612 _matching_new_methods,
2613 _matching_methods_length,
2614 &trace_name_printed);
2615 }
2617 // Unevolving classes may point to methods of the_class directly
2618 // from their constant pool caches, itables, and/or vtables. We
2619 // use the SystemDictionary::classes_do() facility and this helper
2620 // to fix up these pointers.
2621 //
2622 // Note: We currently don't support updating the vtable in
2623 // arrayKlassOops. See Open Issues in jvmtiRedefineClasses.hpp.
2624 void VM_RedefineClasses::adjust_cpool_cache_and_vtable(Klass* k_oop,
2625 ClassLoaderData* initiating_loader,
2626 TRAPS) {
2627 Klass *k = k_oop;
2628 if (k->oop_is_instance()) {
2629 HandleMark hm(THREAD);
2630 InstanceKlass *ik = (InstanceKlass *) k;
2632 // HotSpot specific optimization! HotSpot does not currently
2633 // support delegation from the bootstrap class loader to a
2634 // user-defined class loader. This means that if the bootstrap
2635 // class loader is the initiating class loader, then it will also
2636 // be the defining class loader. This also means that classes
2637 // loaded by the bootstrap class loader cannot refer to classes
2638 // loaded by a user-defined class loader. Note: a user-defined
2639 // class loader can delegate to the bootstrap class loader.
2640 //
2641 // If the current class being redefined has a user-defined class
2642 // loader as its defining class loader, then we can skip all
2643 // classes loaded by the bootstrap class loader.
2644 bool is_user_defined =
2645 InstanceKlass::cast(_the_class_oop)->class_loader() != NULL;
2646 if (is_user_defined && ik->class_loader() == NULL) {
2647 return;
2648 }
2650 // If the class being redefined is java.lang.Object, we need to fix all
2651 // array class vtables also
2652 if (_the_class_oop == SystemDictionary::Object_klass()) {
2653 ik->array_klasses_do(adjust_array_vtable);
2654 }
2656 // This is a very busy routine. We don't want too much tracing
2657 // printed out.
2658 bool trace_name_printed = false;
2660 // Very noisy: only enable this call if you are trying to determine
2661 // that a specific class gets found by this routine.
2662 // RC_TRACE macro has an embedded ResourceMark
2663 // RC_TRACE_WITH_THREAD(0x00100000, THREAD,
2664 // ("adjust check: name=%s", ik->external_name()));
2665 // trace_name_printed = true;
2667 // Fix the vtable embedded in the_class and subclasses of the_class,
2668 // if one exists. We discard scratch_class and we don't keep an
2669 // InstanceKlass around to hold obsolete methods so we don't have
2670 // any other InstanceKlass embedded vtables to update. The vtable
2671 // holds the Method*s for virtual (but not final) methods.
2672 if (ik->vtable_length() > 0 && ik->is_subtype_of(_the_class_oop)) {
2673 // ik->vtable() creates a wrapper object; rm cleans it up
2674 ResourceMark rm(THREAD);
2675 ik->vtable()->adjust_method_entries(_matching_old_methods,
2676 _matching_new_methods,
2677 _matching_methods_length,
2678 &trace_name_printed);
2679 }
2681 // If the current class has an itable and we are either redefining an
2682 // interface or if the current class is a subclass of the_class, then
2683 // we potentially have to fix the itable. If we are redefining an
2684 // interface, then we have to call adjust_method_entries() for
2685 // every InstanceKlass that has an itable since there isn't a
2686 // subclass relationship between an interface and an InstanceKlass.
2687 if (ik->itable_length() > 0 && (_the_class_oop->is_interface()
2688 || ik->is_subclass_of(_the_class_oop))) {
2689 // ik->itable() creates a wrapper object; rm cleans it up
2690 ResourceMark rm(THREAD);
2691 ik->itable()->adjust_method_entries(_matching_old_methods,
2692 _matching_new_methods,
2693 _matching_methods_length,
2694 &trace_name_printed);
2695 }
2697 // The constant pools in other classes (other_cp) can refer to
2698 // methods in the_class. We have to update method information in
2699 // other_cp's cache. If other_cp has a previous version, then we
2700 // have to repeat the process for each previous version. The
2701 // constant pool cache holds the Method*s for non-virtual
2702 // methods and for virtual, final methods.
2703 //
2704 // Special case: if the current class is the_class, then new_cp
2705 // has already been attached to the_class and old_cp has already
2706 // been added as a previous version. The new_cp doesn't have any
2707 // cached references to old methods so it doesn't need to be
2708 // updated. We can simply start with the previous version(s) in
2709 // that case.
2710 constantPoolHandle other_cp;
2711 ConstantPoolCache* cp_cache;
2713 if (k_oop != _the_class_oop) {
2714 // this klass' constant pool cache may need adjustment
2715 other_cp = constantPoolHandle(ik->constants());
2716 cp_cache = other_cp->cache();
2717 if (cp_cache != NULL) {
2718 cp_cache->adjust_method_entries(_matching_old_methods,
2719 _matching_new_methods,
2720 _matching_methods_length,
2721 &trace_name_printed);
2722 }
2723 }
2724 {
2725 ResourceMark rm(THREAD);
2726 // PreviousVersionInfo objects returned via PreviousVersionWalker
2727 // contain a GrowableArray of handles. We have to clean up the
2728 // GrowableArray _after_ the PreviousVersionWalker destructor
2729 // has destroyed the handles.
2730 {
2731 // the previous versions' constant pool caches may need adjustment
2732 PreviousVersionWalker pvw(ik);
2733 for (PreviousVersionInfo * pv_info = pvw.next_previous_version();
2734 pv_info != NULL; pv_info = pvw.next_previous_version()) {
2735 other_cp = pv_info->prev_constant_pool_handle();
2736 cp_cache = other_cp->cache();
2737 if (cp_cache != NULL) {
2738 cp_cache->adjust_method_entries(_matching_old_methods,
2739 _matching_new_methods,
2740 _matching_methods_length,
2741 &trace_name_printed);
2742 }
2743 }
2744 } // pvw is cleaned up
2745 } // rm is cleaned up
2746 }
2747 }
2749 void VM_RedefineClasses::update_jmethod_ids() {
2750 for (int j = 0; j < _matching_methods_length; ++j) {
2751 Method* old_method = _matching_old_methods[j];
2752 jmethodID jmid = old_method->find_jmethod_id_or_null();
2753 if (jmid != NULL) {
2754 // There is a jmethodID, change it to point to the new method
2755 methodHandle new_method_h(_matching_new_methods[j]);
2756 Method::change_method_associated_with_jmethod_id(jmid, new_method_h());
2757 assert(Method::resolve_jmethod_id(jmid) == _matching_new_methods[j],
2758 "should be replaced");
2759 }
2760 }
2761 }
2763 void VM_RedefineClasses::check_methods_and_mark_as_obsolete(
2764 BitMap *emcp_methods, int * emcp_method_count_p) {
2765 *emcp_method_count_p = 0;
2766 int obsolete_count = 0;
2767 int old_index = 0;
2768 for (int j = 0; j < _matching_methods_length; ++j, ++old_index) {
2769 Method* old_method = _matching_old_methods[j];
2770 Method* new_method = _matching_new_methods[j];
2771 Method* old_array_method;
2773 // Maintain an old_index into the _old_methods array by skipping
2774 // deleted methods
2775 while ((old_array_method = _old_methods->at(old_index)) != old_method) {
2776 ++old_index;
2777 }
2779 if (MethodComparator::methods_EMCP(old_method, new_method)) {
2780 // The EMCP definition from JSR-163 requires the bytecodes to be
2781 // the same with the exception of constant pool indices which may
2782 // differ. However, the constants referred to by those indices
2783 // must be the same.
2784 //
2785 // We use methods_EMCP() for comparison since constant pool
2786 // merging can remove duplicate constant pool entries that were
2787 // present in the old method and removed from the rewritten new
2788 // method. A faster binary comparison function would consider the
2789 // old and new methods to be different when they are actually
2790 // EMCP.
2791 //
2792 // The old and new methods are EMCP and you would think that we
2793 // could get rid of one of them here and now and save some space.
2794 // However, the concept of EMCP only considers the bytecodes and
2795 // the constant pool entries in the comparison. Other things,
2796 // e.g., the line number table (LNT) or the local variable table
2797 // (LVT) don't count in the comparison. So the new (and EMCP)
2798 // method can have a new LNT that we need so we can't just
2799 // overwrite the new method with the old method.
2800 //
2801 // When this routine is called, we have already attached the new
2802 // methods to the_class so the old methods are effectively
2803 // overwritten. However, if an old method is still executing,
2804 // then the old method cannot be collected until sometime after
2805 // the old method call has returned. So the overwriting of old
2806 // methods by new methods will save us space except for those
2807 // (hopefully few) old methods that are still executing.
2808 //
2809 // A method refers to a ConstMethod* and this presents another
2810 // possible avenue to space savings. The ConstMethod* in the
2811 // new method contains possibly new attributes (LNT, LVT, etc).
2812 // At first glance, it seems possible to save space by replacing
2813 // the ConstMethod* in the old method with the ConstMethod*
2814 // from the new method. The old and new methods would share the
2815 // same ConstMethod* and we would save the space occupied by
2816 // the old ConstMethod*. However, the ConstMethod* contains
2817 // a back reference to the containing method. Sharing the
2818 // ConstMethod* between two methods could lead to confusion in
2819 // the code that uses the back reference. This would lead to
2820 // brittle code that could be broken in non-obvious ways now or
2821 // in the future.
2822 //
2823 // Another possibility is to copy the ConstMethod* from the new
2824 // method to the old method and then overwrite the new method with
2825 // the old method. Since the ConstMethod* contains the bytecodes
2826 // for the method embedded in the oop, this option would change
2827 // the bytecodes out from under any threads executing the old
2828 // method and make the thread's bcp invalid. Since EMCP requires
2829 // that the bytecodes be the same modulo constant pool indices, it
2830 // is straight forward to compute the correct new bcp in the new
2831 // ConstMethod* from the old bcp in the old ConstMethod*. The
2832 // time consuming part would be searching all the frames in all
2833 // of the threads to find all of the calls to the old method.
2834 //
2835 // It looks like we will have to live with the limited savings
2836 // that we get from effectively overwriting the old methods
2837 // when the new methods are attached to the_class.
2839 // track which methods are EMCP for add_previous_version() call
2840 emcp_methods->set_bit(old_index);
2841 (*emcp_method_count_p)++;
2843 // An EMCP method is _not_ obsolete. An obsolete method has a
2844 // different jmethodID than the current method. An EMCP method
2845 // has the same jmethodID as the current method. Having the
2846 // same jmethodID for all EMCP versions of a method allows for
2847 // a consistent view of the EMCP methods regardless of which
2848 // EMCP method you happen to have in hand. For example, a
2849 // breakpoint set in one EMCP method will work for all EMCP
2850 // versions of the method including the current one.
2851 } else {
2852 // mark obsolete methods as such
2853 old_method->set_is_obsolete();
2854 obsolete_count++;
2856 // obsolete methods need a unique idnum
2857 u2 num = InstanceKlass::cast(_the_class_oop)->next_method_idnum();
2858 if (num != ConstMethod::UNSET_IDNUM) {
2859 // u2 old_num = old_method->method_idnum();
2860 old_method->set_method_idnum(num);
2861 // TO DO: attach obsolete annotations to obsolete method's new idnum
2862 }
2863 // With tracing we try not to "yack" too much. The position of
2864 // this trace assumes there are fewer obsolete methods than
2865 // EMCP methods.
2866 RC_TRACE(0x00000100, ("mark %s(%s) as obsolete",
2867 old_method->name()->as_C_string(),
2868 old_method->signature()->as_C_string()));
2869 }
2870 old_method->set_is_old();
2871 }
2872 for (int i = 0; i < _deleted_methods_length; ++i) {
2873 Method* old_method = _deleted_methods[i];
2875 assert(old_method->vtable_index() < 0,
2876 "cannot delete methods with vtable entries");;
2878 // Mark all deleted methods as old and obsolete
2879 old_method->set_is_old();
2880 old_method->set_is_obsolete();
2881 ++obsolete_count;
2882 // With tracing we try not to "yack" too much. The position of
2883 // this trace assumes there are fewer obsolete methods than
2884 // EMCP methods.
2885 RC_TRACE(0x00000100, ("mark deleted %s(%s) as obsolete",
2886 old_method->name()->as_C_string(),
2887 old_method->signature()->as_C_string()));
2888 }
2889 assert((*emcp_method_count_p + obsolete_count) == _old_methods->length(),
2890 "sanity check");
2891 RC_TRACE(0x00000100, ("EMCP_cnt=%d, obsolete_cnt=%d", *emcp_method_count_p,
2892 obsolete_count));
2893 }
2895 // This internal class transfers the native function registration from old methods
2896 // to new methods. It is designed to handle both the simple case of unchanged
2897 // native methods and the complex cases of native method prefixes being added and/or
2898 // removed.
2899 // It expects only to be used during the VM_RedefineClasses op (a safepoint).
2900 //
2901 // This class is used after the new methods have been installed in "the_class".
2902 //
2903 // So, for example, the following must be handled. Where 'm' is a method and
2904 // a number followed by an underscore is a prefix.
2905 //
2906 // Old Name New Name
2907 // Simple transfer to new method m -> m
2908 // Add prefix m -> 1_m
2909 // Remove prefix 1_m -> m
2910 // Simultaneous add of prefixes m -> 3_2_1_m
2911 // Simultaneous removal of prefixes 3_2_1_m -> m
2912 // Simultaneous add and remove 1_m -> 2_m
2913 // Same, caused by prefix removal only 3_2_1_m -> 3_2_m
2914 //
2915 class TransferNativeFunctionRegistration {
2916 private:
2917 instanceKlassHandle the_class;
2918 int prefix_count;
2919 char** prefixes;
2921 // Recursively search the binary tree of possibly prefixed method names.
2922 // Iteration could be used if all agents were well behaved. Full tree walk is
2923 // more resilent to agents not cleaning up intermediate methods.
2924 // Branch at each depth in the binary tree is:
2925 // (1) without the prefix.
2926 // (2) with the prefix.
2927 // where 'prefix' is the prefix at that 'depth' (first prefix, second prefix,...)
2928 Method* search_prefix_name_space(int depth, char* name_str, size_t name_len,
2929 Symbol* signature) {
2930 TempNewSymbol name_symbol = SymbolTable::probe(name_str, (int)name_len);
2931 if (name_symbol != NULL) {
2932 Method* method = the_class()->lookup_method(name_symbol, signature);
2933 if (method != NULL) {
2934 // Even if prefixed, intermediate methods must exist.
2935 if (method->is_native()) {
2936 // Wahoo, we found a (possibly prefixed) version of the method, return it.
2937 return method;
2938 }
2939 if (depth < prefix_count) {
2940 // Try applying further prefixes (other than this one).
2941 method = search_prefix_name_space(depth+1, name_str, name_len, signature);
2942 if (method != NULL) {
2943 return method; // found
2944 }
2946 // Try adding this prefix to the method name and see if it matches
2947 // another method name.
2948 char* prefix = prefixes[depth];
2949 size_t prefix_len = strlen(prefix);
2950 size_t trial_len = name_len + prefix_len;
2951 char* trial_name_str = NEW_RESOURCE_ARRAY(char, trial_len + 1);
2952 strcpy(trial_name_str, prefix);
2953 strcat(trial_name_str, name_str);
2954 method = search_prefix_name_space(depth+1, trial_name_str, trial_len,
2955 signature);
2956 if (method != NULL) {
2957 // If found along this branch, it was prefixed, mark as such
2958 method->set_is_prefixed_native();
2959 return method; // found
2960 }
2961 }
2962 }
2963 }
2964 return NULL; // This whole branch bore nothing
2965 }
2967 // Return the method name with old prefixes stripped away.
2968 char* method_name_without_prefixes(Method* method) {
2969 Symbol* name = method->name();
2970 char* name_str = name->as_utf8();
2972 // Old prefixing may be defunct, strip prefixes, if any.
2973 for (int i = prefix_count-1; i >= 0; i--) {
2974 char* prefix = prefixes[i];
2975 size_t prefix_len = strlen(prefix);
2976 if (strncmp(prefix, name_str, prefix_len) == 0) {
2977 name_str += prefix_len;
2978 }
2979 }
2980 return name_str;
2981 }
2983 // Strip any prefixes off the old native method, then try to find a
2984 // (possibly prefixed) new native that matches it.
2985 Method* strip_and_search_for_new_native(Method* method) {
2986 ResourceMark rm;
2987 char* name_str = method_name_without_prefixes(method);
2988 return search_prefix_name_space(0, name_str, strlen(name_str),
2989 method->signature());
2990 }
2992 public:
2994 // Construct a native method transfer processor for this class.
2995 TransferNativeFunctionRegistration(instanceKlassHandle _the_class) {
2996 assert(SafepointSynchronize::is_at_safepoint(), "sanity check");
2998 the_class = _the_class;
2999 prefixes = JvmtiExport::get_all_native_method_prefixes(&prefix_count);
3000 }
3002 // Attempt to transfer any of the old or deleted methods that are native
3003 void transfer_registrations(Method** old_methods, int methods_length) {
3004 for (int j = 0; j < methods_length; j++) {
3005 Method* old_method = old_methods[j];
3007 if (old_method->is_native() && old_method->has_native_function()) {
3008 Method* new_method = strip_and_search_for_new_native(old_method);
3009 if (new_method != NULL) {
3010 // Actually set the native function in the new method.
3011 // Redefine does not send events (except CFLH), certainly not this
3012 // behind the scenes re-registration.
3013 new_method->set_native_function(old_method->native_function(),
3014 !Method::native_bind_event_is_interesting);
3015 }
3016 }
3017 }
3018 }
3019 };
3021 // Don't lose the association between a native method and its JNI function.
3022 void VM_RedefineClasses::transfer_old_native_function_registrations(instanceKlassHandle the_class) {
3023 TransferNativeFunctionRegistration transfer(the_class);
3024 transfer.transfer_registrations(_deleted_methods, _deleted_methods_length);
3025 transfer.transfer_registrations(_matching_old_methods, _matching_methods_length);
3026 }
3028 // Deoptimize all compiled code that depends on this class.
3029 //
3030 // If the can_redefine_classes capability is obtained in the onload
3031 // phase then the compiler has recorded all dependencies from startup.
3032 // In that case we need only deoptimize and throw away all compiled code
3033 // that depends on the class.
3034 //
3035 // If can_redefine_classes is obtained sometime after the onload
3036 // phase then the dependency information may be incomplete. In that case
3037 // the first call to RedefineClasses causes all compiled code to be
3038 // thrown away. As can_redefine_classes has been obtained then
3039 // all future compilations will record dependencies so second and
3040 // subsequent calls to RedefineClasses need only throw away code
3041 // that depends on the class.
3042 //
3043 void VM_RedefineClasses::flush_dependent_code(instanceKlassHandle k_h, TRAPS) {
3044 assert_locked_or_safepoint(Compile_lock);
3046 // All dependencies have been recorded from startup or this is a second or
3047 // subsequent use of RedefineClasses
3048 if (JvmtiExport::all_dependencies_are_recorded()) {
3049 Universe::flush_evol_dependents_on(k_h);
3050 } else {
3051 CodeCache::mark_all_nmethods_for_deoptimization();
3053 ResourceMark rm(THREAD);
3054 DeoptimizationMarker dm;
3056 // Deoptimize all activations depending on marked nmethods
3057 Deoptimization::deoptimize_dependents();
3059 // Make the dependent methods not entrant (in VM_Deoptimize they are made zombies)
3060 CodeCache::make_marked_nmethods_not_entrant();
3062 // From now on we know that the dependency information is complete
3063 JvmtiExport::set_all_dependencies_are_recorded(true);
3064 }
3065 }
3067 void VM_RedefineClasses::compute_added_deleted_matching_methods() {
3068 Method* old_method;
3069 Method* new_method;
3071 _matching_old_methods = NEW_RESOURCE_ARRAY(Method*, _old_methods->length());
3072 _matching_new_methods = NEW_RESOURCE_ARRAY(Method*, _old_methods->length());
3073 _added_methods = NEW_RESOURCE_ARRAY(Method*, _new_methods->length());
3074 _deleted_methods = NEW_RESOURCE_ARRAY(Method*, _old_methods->length());
3076 _matching_methods_length = 0;
3077 _deleted_methods_length = 0;
3078 _added_methods_length = 0;
3080 int nj = 0;
3081 int oj = 0;
3082 while (true) {
3083 if (oj >= _old_methods->length()) {
3084 if (nj >= _new_methods->length()) {
3085 break; // we've looked at everything, done
3086 }
3087 // New method at the end
3088 new_method = _new_methods->at(nj);
3089 _added_methods[_added_methods_length++] = new_method;
3090 ++nj;
3091 } else if (nj >= _new_methods->length()) {
3092 // Old method, at the end, is deleted
3093 old_method = _old_methods->at(oj);
3094 _deleted_methods[_deleted_methods_length++] = old_method;
3095 ++oj;
3096 } else {
3097 old_method = _old_methods->at(oj);
3098 new_method = _new_methods->at(nj);
3099 if (old_method->name() == new_method->name()) {
3100 if (old_method->signature() == new_method->signature()) {
3101 _matching_old_methods[_matching_methods_length ] = old_method;
3102 _matching_new_methods[_matching_methods_length++] = new_method;
3103 ++nj;
3104 ++oj;
3105 } else {
3106 // added overloaded have already been moved to the end,
3107 // so this is a deleted overloaded method
3108 _deleted_methods[_deleted_methods_length++] = old_method;
3109 ++oj;
3110 }
3111 } else { // names don't match
3112 if (old_method->name()->fast_compare(new_method->name()) > 0) {
3113 // new method
3114 _added_methods[_added_methods_length++] = new_method;
3115 ++nj;
3116 } else {
3117 // deleted method
3118 _deleted_methods[_deleted_methods_length++] = old_method;
3119 ++oj;
3120 }
3121 }
3122 }
3123 }
3124 assert(_matching_methods_length + _deleted_methods_length == _old_methods->length(), "sanity");
3125 assert(_matching_methods_length + _added_methods_length == _new_methods->length(), "sanity");
3126 }
3130 // Install the redefinition of a class:
3131 // - house keeping (flushing breakpoints and caches, deoptimizing
3132 // dependent compiled code)
3133 // - replacing parts in the_class with parts from scratch_class
3134 // - adding a weak reference to track the obsolete but interesting
3135 // parts of the_class
3136 // - adjusting constant pool caches and vtables in other classes
3137 // that refer to methods in the_class. These adjustments use the
3138 // SystemDictionary::classes_do() facility which only allows
3139 // a helper method to be specified. The interesting parameters
3140 // that we would like to pass to the helper method are saved in
3141 // static global fields in the VM operation.
3142 void VM_RedefineClasses::redefine_single_class(jclass the_jclass,
3143 Klass* scratch_class_oop, TRAPS) {
3145 HandleMark hm(THREAD); // make sure handles from this call are freed
3146 RC_TIMER_START(_timer_rsc_phase1);
3148 instanceKlassHandle scratch_class(scratch_class_oop);
3150 oop the_class_mirror = JNIHandles::resolve_non_null(the_jclass);
3151 Klass* the_class_oop = java_lang_Class::as_Klass(the_class_mirror);
3152 instanceKlassHandle the_class = instanceKlassHandle(THREAD, the_class_oop);
3154 #ifndef JVMTI_KERNEL
3155 // Remove all breakpoints in methods of this class
3156 JvmtiBreakpoints& jvmti_breakpoints = JvmtiCurrentBreakpoints::get_jvmti_breakpoints();
3157 jvmti_breakpoints.clearall_in_class_at_safepoint(the_class_oop);
3158 #endif // !JVMTI_KERNEL
3160 if (the_class_oop == Universe::reflect_invoke_cache()->klass()) {
3161 // We are redefining java.lang.reflect.Method. Method.invoke() is
3162 // cached and users of the cache care about each active version of
3163 // the method so we have to track this previous version.
3164 // Do this before methods get switched
3165 Universe::reflect_invoke_cache()->add_previous_version(
3166 the_class->method_with_idnum(Universe::reflect_invoke_cache()->method_idnum()));
3167 }
3169 // Deoptimize all compiled code that depends on this class
3170 flush_dependent_code(the_class, THREAD);
3172 _old_methods = the_class->methods();
3173 _new_methods = scratch_class->methods();
3174 _the_class_oop = the_class_oop;
3175 compute_added_deleted_matching_methods();
3176 update_jmethod_ids();
3178 // Attach new constant pool to the original klass. The original
3179 // klass still refers to the old constant pool (for now).
3180 scratch_class->constants()->set_pool_holder(the_class());
3182 #if 0
3183 // In theory, with constant pool merging in place we should be able
3184 // to save space by using the new, merged constant pool in place of
3185 // the old constant pool(s). By "pool(s)" I mean the constant pool in
3186 // the klass version we are replacing now and any constant pool(s) in
3187 // previous versions of klass. Nice theory, doesn't work in practice.
3188 // When this code is enabled, even simple programs throw NullPointer
3189 // exceptions. I'm guessing that this is caused by some constant pool
3190 // cache difference between the new, merged constant pool and the
3191 // constant pool that was just being used by the klass. I'm keeping
3192 // this code around to archive the idea, but the code has to remain
3193 // disabled for now.
3195 // Attach each old method to the new constant pool. This can be
3196 // done here since we are past the bytecode verification and
3197 // constant pool optimization phases.
3198 for (int i = _old_methods->length() - 1; i >= 0; i--) {
3199 Method* method = _old_methods->at(i);
3200 method->set_constants(scratch_class->constants());
3201 }
3203 {
3204 // walk all previous versions of the klass
3205 InstanceKlass *ik = (InstanceKlass *)the_class();
3206 PreviousVersionWalker pvw(ik);
3207 instanceKlassHandle ikh;
3208 do {
3209 ikh = pvw.next_previous_version();
3210 if (!ikh.is_null()) {
3211 ik = ikh();
3213 // attach previous version of klass to the new constant pool
3214 ik->set_constants(scratch_class->constants());
3216 // Attach each method in the previous version of klass to the
3217 // new constant pool
3218 Array<Method*>* prev_methods = ik->methods();
3219 for (int i = prev_methods->length() - 1; i >= 0; i--) {
3220 Method* method = prev_methods->at(i);
3221 method->set_constants(scratch_class->constants());
3222 }
3223 }
3224 } while (!ikh.is_null());
3225 }
3226 #endif
3228 // Replace methods and constantpool
3229 the_class->set_methods(_new_methods);
3230 scratch_class->set_methods(_old_methods); // To prevent potential GCing of the old methods,
3231 // and to be able to undo operation easily.
3233 ConstantPool* old_constants = the_class->constants();
3234 the_class->set_constants(scratch_class->constants());
3235 scratch_class->set_constants(old_constants); // See the previous comment.
3236 #if 0
3237 // We are swapping the guts of "the new class" with the guts of "the
3238 // class". Since the old constant pool has just been attached to "the
3239 // new class", it seems logical to set the pool holder in the old
3240 // constant pool also. However, doing this will change the observable
3241 // class hierarchy for any old methods that are still executing. A
3242 // method can query the identity of its "holder" and this query uses
3243 // the method's constant pool link to find the holder. The change in
3244 // holding class from "the class" to "the new class" can confuse
3245 // things.
3246 //
3247 // Setting the old constant pool's holder will also cause
3248 // verification done during vtable initialization below to fail.
3249 // During vtable initialization, the vtable's class is verified to be
3250 // a subtype of the method's holder. The vtable's class is "the
3251 // class" and the method's holder is gotten from the constant pool
3252 // link in the method itself. For "the class"'s directly implemented
3253 // methods, the method holder is "the class" itself (as gotten from
3254 // the new constant pool). The check works fine in this case. The
3255 // check also works fine for methods inherited from super classes.
3256 //
3257 // Miranda methods are a little more complicated. A miranda method is
3258 // provided by an interface when the class implementing the interface
3259 // does not provide its own method. These interfaces are implemented
3260 // internally as an InstanceKlass. These special instanceKlasses
3261 // share the constant pool of the class that "implements" the
3262 // interface. By sharing the constant pool, the method holder of a
3263 // miranda method is the class that "implements" the interface. In a
3264 // non-redefine situation, the subtype check works fine. However, if
3265 // the old constant pool's pool holder is modified, then the check
3266 // fails because there is no class hierarchy relationship between the
3267 // vtable's class and "the new class".
3269 old_constants->set_pool_holder(scratch_class());
3270 #endif
3272 // track which methods are EMCP for add_previous_version() call below
3273 BitMap emcp_methods(_old_methods->length());
3274 int emcp_method_count = 0;
3275 emcp_methods.clear(); // clears 0..(length() - 1)
3276 check_methods_and_mark_as_obsolete(&emcp_methods, &emcp_method_count);
3277 transfer_old_native_function_registrations(the_class);
3279 // The class file bytes from before any retransformable agents mucked
3280 // with them was cached on the scratch class, move to the_class.
3281 // Note: we still want to do this if nothing needed caching since it
3282 // should get cleared in the_class too.
3283 if (the_class->get_cached_class_file_bytes() == 0) {
3284 // the_class doesn't have a cache yet so copy it
3285 the_class->set_cached_class_file(
3286 scratch_class->get_cached_class_file_bytes(),
3287 scratch_class->get_cached_class_file_len());
3288 }
3289 #ifndef PRODUCT
3290 else {
3291 assert(the_class->get_cached_class_file_bytes() ==
3292 scratch_class->get_cached_class_file_bytes(), "cache ptrs must match");
3293 assert(the_class->get_cached_class_file_len() ==
3294 scratch_class->get_cached_class_file_len(), "cache lens must match");
3295 }
3296 #endif
3298 // Replace inner_classes
3299 Array<u2>* old_inner_classes = the_class->inner_classes();
3300 the_class->set_inner_classes(scratch_class->inner_classes());
3301 scratch_class->set_inner_classes(old_inner_classes);
3303 // Initialize the vtable and interface table after
3304 // methods have been rewritten
3305 {
3306 ResourceMark rm(THREAD);
3307 // no exception should happen here since we explicitly
3308 // do not check loader constraints.
3309 // compare_and_normalize_class_versions has already checked:
3310 // - classloaders unchanged, signatures unchanged
3311 // - all instanceKlasses for redefined classes reused & contents updated
3312 the_class->vtable()->initialize_vtable(false, THREAD);
3313 the_class->itable()->initialize_itable(false, THREAD);
3314 assert(!HAS_PENDING_EXCEPTION || (THREAD->pending_exception()->is_a(SystemDictionary::ThreadDeath_klass())), "redefine exception");
3315 }
3317 // Leave arrays of jmethodIDs and itable index cache unchanged
3319 // Copy the "source file name" attribute from new class version
3320 the_class->set_source_file_name(scratch_class->source_file_name());
3322 // Copy the "source debug extension" attribute from new class version
3323 the_class->set_source_debug_extension(
3324 scratch_class->source_debug_extension(),
3325 scratch_class->source_debug_extension() == NULL ? 0 :
3326 (int)strlen(scratch_class->source_debug_extension()));
3328 // Use of javac -g could be different in the old and the new
3329 if (scratch_class->access_flags().has_localvariable_table() !=
3330 the_class->access_flags().has_localvariable_table()) {
3332 AccessFlags flags = the_class->access_flags();
3333 if (scratch_class->access_flags().has_localvariable_table()) {
3334 flags.set_has_localvariable_table();
3335 } else {
3336 flags.clear_has_localvariable_table();
3337 }
3338 the_class->set_access_flags(flags);
3339 }
3341 // Replace annotation fields value
3342 Annotations* old_annotations = the_class->annotations();
3343 the_class->set_annotations(scratch_class->annotations());
3344 scratch_class->set_annotations(old_annotations);
3346 // Replace minor version number of class file
3347 u2 old_minor_version = the_class->minor_version();
3348 the_class->set_minor_version(scratch_class->minor_version());
3349 scratch_class->set_minor_version(old_minor_version);
3351 // Replace major version number of class file
3352 u2 old_major_version = the_class->major_version();
3353 the_class->set_major_version(scratch_class->major_version());
3354 scratch_class->set_major_version(old_major_version);
3356 // Replace CP indexes for class and name+type of enclosing method
3357 u2 old_class_idx = the_class->enclosing_method_class_index();
3358 u2 old_method_idx = the_class->enclosing_method_method_index();
3359 the_class->set_enclosing_method_indices(
3360 scratch_class->enclosing_method_class_index(),
3361 scratch_class->enclosing_method_method_index());
3362 scratch_class->set_enclosing_method_indices(old_class_idx, old_method_idx);
3364 // keep track of previous versions of this class
3365 the_class->add_previous_version(scratch_class, &emcp_methods,
3366 emcp_method_count);
3368 RC_TIMER_STOP(_timer_rsc_phase1);
3369 RC_TIMER_START(_timer_rsc_phase2);
3371 // Adjust constantpool caches and vtables for all classes
3372 // that reference methods of the evolved class.
3373 SystemDictionary::classes_do(adjust_cpool_cache_and_vtable, THREAD);
3375 // Fix Resolution Error table also to remove old constant pools
3376 SystemDictionary::delete_resolution_error(old_constants);
3378 if (the_class->oop_map_cache() != NULL) {
3379 // Flush references to any obsolete methods from the oop map cache
3380 // so that obsolete methods are not pinned.
3381 the_class->oop_map_cache()->flush_obsolete_entries();
3382 }
3384 // increment the classRedefinedCount field in the_class and in any
3385 // direct and indirect subclasses of the_class
3386 increment_class_counter((InstanceKlass *)the_class(), THREAD);
3388 // RC_TRACE macro has an embedded ResourceMark
3389 RC_TRACE_WITH_THREAD(0x00000001, THREAD,
3390 ("redefined name=%s, count=%d (avail_mem=" UINT64_FORMAT "K)",
3391 the_class->external_name(),
3392 java_lang_Class::classRedefinedCount(the_class_mirror),
3393 os::available_memory() >> 10));
3395 RC_TIMER_STOP(_timer_rsc_phase2);
3396 } // end redefine_single_class()
3399 // Increment the classRedefinedCount field in the specific InstanceKlass
3400 // and in all direct and indirect subclasses.
3401 void VM_RedefineClasses::increment_class_counter(InstanceKlass *ik, TRAPS) {
3402 oop class_mirror = ik->java_mirror();
3403 Klass* class_oop = java_lang_Class::as_Klass(class_mirror);
3404 int new_count = java_lang_Class::classRedefinedCount(class_mirror) + 1;
3405 java_lang_Class::set_classRedefinedCount(class_mirror, new_count);
3407 if (class_oop != _the_class_oop) {
3408 // _the_class_oop count is printed at end of redefine_single_class()
3409 RC_TRACE_WITH_THREAD(0x00000008, THREAD,
3410 ("updated count in subclass=%s to %d", ik->external_name(), new_count));
3411 }
3413 for (Klass *subk = ik->subklass(); subk != NULL;
3414 subk = subk->next_sibling()) {
3415 if (subk->oop_is_instance()) {
3416 // Only update instanceKlasses
3417 InstanceKlass *subik = (InstanceKlass*)subk;
3418 // recursively do subclasses of the current subclass
3419 increment_class_counter(subik, THREAD);
3420 }
3421 }
3422 }
3424 #ifndef PRODUCT
3425 void VM_RedefineClasses::check_class(Klass* k_oop,
3426 ClassLoaderData* initiating_loader,
3427 TRAPS) {
3428 Klass *k = k_oop;
3429 if (k->oop_is_instance()) {
3430 HandleMark hm(THREAD);
3431 InstanceKlass *ik = (InstanceKlass *) k;
3433 if (ik->vtable_length() > 0) {
3434 ResourceMark rm(THREAD);
3435 if (!ik->vtable()->check_no_old_entries()) {
3436 tty->print_cr("klassVtable::check_no_old_entries failure -- OLD method found -- class: %s", ik->signature_name());
3437 ik->vtable()->dump_vtable();
3438 assert(false, "OLD method found");
3439 }
3440 }
3441 if (ik->itable_length() > 0) {
3442 ResourceMark rm(THREAD);
3443 if (!ik->itable()->check_no_old_entries()) {
3444 tty->print_cr("klassItable::check_no_old_entries failure -- OLD method found -- class: %s", ik->signature_name());
3445 assert(false, "OLD method found");
3446 }
3447 }
3448 // Check that the constant pool cache has no deleted entries.
3449 if (ik->constants() != NULL &&
3450 ik->constants()->cache() != NULL &&
3451 !ik->constants()->cache()->check_no_old_entries()) {
3452 tty->print_cr("klassVtable::check_no_old_entries failure -- OLD method found -- class: %s", ik->signature_name());
3453 assert(false, "OLD method found");
3454 }
3455 }
3456 }
3458 void VM_RedefineClasses::dump_methods() {
3459 int j;
3460 tty->print_cr("_old_methods --");
3461 for (j = 0; j < _old_methods->length(); ++j) {
3462 Method* m = _old_methods->at(j);
3463 tty->print("%4d (%5d) ", j, m->vtable_index());
3464 m->access_flags().print_on(tty);
3465 tty->print(" -- ");
3466 m->print_name(tty);
3467 tty->cr();
3468 }
3469 tty->print_cr("_new_methods --");
3470 for (j = 0; j < _new_methods->length(); ++j) {
3471 Method* m = _new_methods->at(j);
3472 tty->print("%4d (%5d) ", j, m->vtable_index());
3473 m->access_flags().print_on(tty);
3474 tty->print(" -- ");
3475 m->print_name(tty);
3476 tty->cr();
3477 }
3478 tty->print_cr("_matching_(old/new)_methods --");
3479 for (j = 0; j < _matching_methods_length; ++j) {
3480 Method* m = _matching_old_methods[j];
3481 tty->print("%4d (%5d) ", j, m->vtable_index());
3482 m->access_flags().print_on(tty);
3483 tty->print(" -- ");
3484 m->print_name(tty);
3485 tty->cr();
3486 m = _matching_new_methods[j];
3487 tty->print(" (%5d) ", m->vtable_index());
3488 m->access_flags().print_on(tty);
3489 tty->cr();
3490 }
3491 tty->print_cr("_deleted_methods --");
3492 for (j = 0; j < _deleted_methods_length; ++j) {
3493 Method* m = _deleted_methods[j];
3494 tty->print("%4d (%5d) ", j, m->vtable_index());
3495 m->access_flags().print_on(tty);
3496 tty->print(" -- ");
3497 m->print_name(tty);
3498 tty->cr();
3499 }
3500 tty->print_cr("_added_methods --");
3501 for (j = 0; j < _added_methods_length; ++j) {
3502 Method* m = _added_methods[j];
3503 tty->print("%4d (%5d) ", j, m->vtable_index());
3504 m->access_flags().print_on(tty);
3505 tty->print(" -- ");
3506 m->print_name(tty);
3507 tty->cr();
3508 }
3509 }
3510 #endif