1 /*
2 * Copyright (c) 2003, 2009, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
24
25 # include "incls/_precompiled.incl"
26 # include "incls/_jvmtiRedefineClasses.cpp.incl"
27
28
29 objArrayOop VM_RedefineClasses::_old_methods = NULL;
30 objArrayOop VM_RedefineClasses::_new_methods = NULL;
31 methodOop* VM_RedefineClasses::_matching_old_methods = NULL;
32 methodOop* VM_RedefineClasses::_matching_new_methods = NULL;
33 methodOop* VM_RedefineClasses::_deleted_methods = NULL;
34 methodOop* VM_RedefineClasses::_added_methods = NULL;
35 int VM_RedefineClasses::_matching_methods_length = 0;
36 int VM_RedefineClasses::_deleted_methods_length = 0;
37 int VM_RedefineClasses::_added_methods_length = 0;
38 klassOop VM_RedefineClasses::_the_class_oop = NULL;
39
40
41 VM_RedefineClasses::VM_RedefineClasses(jint class_count,
42 const jvmtiClassDefinition *class_defs,
43 JvmtiClassLoadKind class_load_kind) {
44 _class_count = class_count;
45 _class_defs = class_defs;
46 _class_load_kind = class_load_kind;
47 _res = JVMTI_ERROR_NONE;
48 }
49
50 bool VM_RedefineClasses::doit_prologue() {
51 if (_class_count == 0) {
52 _res = JVMTI_ERROR_NONE;
53 return false;
54 }
55 if (_class_defs == NULL) {
56 _res = JVMTI_ERROR_NULL_POINTER;
57 return false;
58 }
59 for (int i = 0; i < _class_count; i++) {
60 if (_class_defs[i].klass == NULL) {
61 _res = JVMTI_ERROR_INVALID_CLASS;
62 return false;
63 }
64 if (_class_defs[i].class_byte_count == 0) {
65 _res = JVMTI_ERROR_INVALID_CLASS_FORMAT;
66 return false;
67 }
68 if (_class_defs[i].class_bytes == NULL) {
69 _res = JVMTI_ERROR_NULL_POINTER;
70 return false;
71 }
72 }
73
74 // Start timer after all the sanity checks; not quite accurate, but
75 // better than adding a bunch of stop() calls.
76 RC_TIMER_START(_timer_vm_op_prologue);
77
78 // We first load new class versions in the prologue, because somewhere down the
79 // call chain it is required that the current thread is a Java thread.
80 _res = load_new_class_versions(Thread::current());
81 if (_res != JVMTI_ERROR_NONE) {
82 // Free os::malloc allocated memory in load_new_class_version.
83 os::free(_scratch_classes);
84 RC_TIMER_STOP(_timer_vm_op_prologue);
85 return false;
86 }
87
88 RC_TIMER_STOP(_timer_vm_op_prologue);
89 return true;
90 }
91
92 void VM_RedefineClasses::doit() {
93 Thread *thread = Thread::current();
94
95 if (UseSharedSpaces) {
96 // Sharing is enabled so we remap the shared readonly space to
97 // shared readwrite, private just in case we need to redefine
98 // a shared class. We do the remap during the doit() phase of
99 // the safepoint to be safer.
100 if (!CompactingPermGenGen::remap_shared_readonly_as_readwrite()) {
101 RC_TRACE_WITH_THREAD(0x00000001, thread,
102 ("failed to remap shared readonly space to readwrite, private"));
103 _res = JVMTI_ERROR_INTERNAL;
104 return;
105 }
106 }
107
108 for (int i = 0; i < _class_count; i++) {
109 redefine_single_class(_class_defs[i].klass, _scratch_classes[i], thread);
110 }
111 // Disable any dependent concurrent compilations
112 SystemDictionary::notice_modification();
113
114 // Set flag indicating that some invariants are no longer true.
115 // See jvmtiExport.hpp for detailed explanation.
116 JvmtiExport::set_has_redefined_a_class();
117
118 #ifdef ASSERT
119 SystemDictionary::classes_do(check_class, thread);
120 #endif
121 }
122
123 void VM_RedefineClasses::doit_epilogue() {
124 // Free os::malloc allocated memory.
125 // The memory allocated in redefine will be free'ed in next VM operation.
126 os::free(_scratch_classes);
127
128 if (RC_TRACE_ENABLED(0x00000004)) {
129 // Used to have separate timers for "doit" and "all", but the timer
130 // overhead skewed the measurements.
131 jlong doit_time = _timer_rsc_phase1.milliseconds() +
132 _timer_rsc_phase2.milliseconds();
133 jlong all_time = _timer_vm_op_prologue.milliseconds() + doit_time;
134
135 RC_TRACE(0x00000004, ("vm_op: all=" UINT64_FORMAT
136 " prologue=" UINT64_FORMAT " doit=" UINT64_FORMAT, all_time,
137 _timer_vm_op_prologue.milliseconds(), doit_time));
138 RC_TRACE(0x00000004,
139 ("redefine_single_class: phase1=" UINT64_FORMAT " phase2=" UINT64_FORMAT,
140 _timer_rsc_phase1.milliseconds(), _timer_rsc_phase2.milliseconds()));
141 }
142 }
143
144 bool VM_RedefineClasses::is_modifiable_class(oop klass_mirror) {
145 // classes for primitives cannot be redefined
146 if (java_lang_Class::is_primitive(klass_mirror)) {
147 return false;
148 }
149 klassOop the_class_oop = java_lang_Class::as_klassOop(klass_mirror);
150 // classes for arrays cannot be redefined
151 if (the_class_oop == NULL || !Klass::cast(the_class_oop)->oop_is_instance()) {
152 return false;
153 }
154 return true;
155 }
156
157 // Append the current entry at scratch_i in scratch_cp to *merge_cp_p
158 // where the end of *merge_cp_p is specified by *merge_cp_length_p. For
159 // direct CP entries, there is just the current entry to append. For
160 // indirect and double-indirect CP entries, there are zero or more
161 // referenced CP entries along with the current entry to append.
162 // Indirect and double-indirect CP entries are handled by recursive
163 // calls to append_entry() as needed. The referenced CP entries are
164 // always appended to *merge_cp_p before the referee CP entry. These
165 // referenced CP entries may already exist in *merge_cp_p in which case
166 // there is nothing extra to append and only the current entry is
167 // appended.
168 void VM_RedefineClasses::append_entry(constantPoolHandle scratch_cp,
169 int scratch_i, constantPoolHandle *merge_cp_p, int *merge_cp_length_p,
170 TRAPS) {
171
172 // append is different depending on entry tag type
173 switch (scratch_cp->tag_at(scratch_i).value()) {
174
175 // The old verifier is implemented outside the VM. It loads classes,
176 // but does not resolve constant pool entries directly so we never
177 // see Class entries here with the old verifier. Similarly the old
178 // verifier does not like Class entries in the input constant pool.
179 // The split-verifier is implemented in the VM so it can optionally
180 // and directly resolve constant pool entries to load classes. The
181 // split-verifier can accept either Class entries or UnresolvedClass
182 // entries in the input constant pool. We revert the appended copy
183 // back to UnresolvedClass so that either verifier will be happy
184 // with the constant pool entry.
185 case JVM_CONSTANT_Class:
186 {
187 // revert the copy to JVM_CONSTANT_UnresolvedClass
188 (*merge_cp_p)->unresolved_klass_at_put(*merge_cp_length_p,
189 scratch_cp->klass_name_at(scratch_i));
190
191 if (scratch_i != *merge_cp_length_p) {
192 // The new entry in *merge_cp_p is at a different index than
193 // the new entry in scratch_cp so we need to map the index values.
194 map_index(scratch_cp, scratch_i, *merge_cp_length_p);
195 }
196 (*merge_cp_length_p)++;
197 } break;
198
199 // these are direct CP entries so they can be directly appended,
200 // but double and long take two constant pool entries
201 case JVM_CONSTANT_Double: // fall through
202 case JVM_CONSTANT_Long:
203 {
204 scratch_cp->copy_entry_to(scratch_i, *merge_cp_p, *merge_cp_length_p,
205 THREAD);
206
207 if (scratch_i != *merge_cp_length_p) {
208 // The new entry in *merge_cp_p is at a different index than
209 // the new entry in scratch_cp so we need to map the index values.
210 map_index(scratch_cp, scratch_i, *merge_cp_length_p);
211 }
212 (*merge_cp_length_p) += 2;
213 } break;
214
215 // these are direct CP entries so they can be directly appended
216 case JVM_CONSTANT_Float: // fall through
217 case JVM_CONSTANT_Integer: // fall through
218 case JVM_CONSTANT_Utf8: // fall through
219
220 // This was an indirect CP entry, but it has been changed into
221 // an interned string so this entry can be directly appended.
222 case JVM_CONSTANT_String: // fall through
223
224 // These were indirect CP entries, but they have been changed into
225 // symbolOops so these entries can be directly appended.
226 case JVM_CONSTANT_UnresolvedClass: // fall through
227 case JVM_CONSTANT_UnresolvedString:
228 {
229 scratch_cp->copy_entry_to(scratch_i, *merge_cp_p, *merge_cp_length_p,
230 THREAD);
231
232 if (scratch_i != *merge_cp_length_p) {
233 // The new entry in *merge_cp_p is at a different index than
234 // the new entry in scratch_cp so we need to map the index values.
235 map_index(scratch_cp, scratch_i, *merge_cp_length_p);
236 }
237 (*merge_cp_length_p)++;
238 } break;
239
240 // this is an indirect CP entry so it needs special handling
241 case JVM_CONSTANT_NameAndType:
242 {
243 int name_ref_i = scratch_cp->name_ref_index_at(scratch_i);
244 int new_name_ref_i = 0;
245 bool match = (name_ref_i < *merge_cp_length_p) &&
246 scratch_cp->compare_entry_to(name_ref_i, *merge_cp_p, name_ref_i,
247 THREAD);
248 if (!match) {
249 // forward reference in *merge_cp_p or not a direct match
250
251 int found_i = scratch_cp->find_matching_entry(name_ref_i, *merge_cp_p,
252 THREAD);
253 if (found_i != 0) {
254 guarantee(found_i != name_ref_i,
255 "compare_entry_to() and find_matching_entry() do not agree");
256
257 // Found a matching entry somewhere else in *merge_cp_p so
258 // just need a mapping entry.
259 new_name_ref_i = found_i;
260 map_index(scratch_cp, name_ref_i, found_i);
261 } else {
262 // no match found so we have to append this entry to *merge_cp_p
263 append_entry(scratch_cp, name_ref_i, merge_cp_p, merge_cp_length_p,
264 THREAD);
265 // The above call to append_entry() can only append one entry
266 // so the post call query of *merge_cp_length_p is only for
267 // the sake of consistency.
268 new_name_ref_i = *merge_cp_length_p - 1;
269 }
270 }
271
272 int signature_ref_i = scratch_cp->signature_ref_index_at(scratch_i);
273 int new_signature_ref_i = 0;
274 match = (signature_ref_i < *merge_cp_length_p) &&
275 scratch_cp->compare_entry_to(signature_ref_i, *merge_cp_p,
276 signature_ref_i, THREAD);
277 if (!match) {
278 // forward reference in *merge_cp_p or not a direct match
279
280 int found_i = scratch_cp->find_matching_entry(signature_ref_i,
281 *merge_cp_p, THREAD);
282 if (found_i != 0) {
283 guarantee(found_i != signature_ref_i,
284 "compare_entry_to() and find_matching_entry() do not agree");
285
286 // Found a matching entry somewhere else in *merge_cp_p so
287 // just need a mapping entry.
288 new_signature_ref_i = found_i;
289 map_index(scratch_cp, signature_ref_i, found_i);
290 } else {
291 // no match found so we have to append this entry to *merge_cp_p
292 append_entry(scratch_cp, signature_ref_i, merge_cp_p,
293 merge_cp_length_p, THREAD);
294 // The above call to append_entry() can only append one entry
295 // so the post call query of *merge_cp_length_p is only for
296 // the sake of consistency.
297 new_signature_ref_i = *merge_cp_length_p - 1;
298 }
299 }
300
301 // If the referenced entries already exist in *merge_cp_p, then
302 // both new_name_ref_i and new_signature_ref_i will both be 0.
303 // In that case, all we are appending is the current entry.
304 if (new_name_ref_i == 0) {
305 new_name_ref_i = name_ref_i;
306 } else {
307 RC_TRACE(0x00080000,
308 ("NameAndType entry@%d name_ref_index change: %d to %d",
309 *merge_cp_length_p, name_ref_i, new_name_ref_i));
310 }
311 if (new_signature_ref_i == 0) {
312 new_signature_ref_i = signature_ref_i;
313 } else {
314 RC_TRACE(0x00080000,
315 ("NameAndType entry@%d signature_ref_index change: %d to %d",
316 *merge_cp_length_p, signature_ref_i, new_signature_ref_i));
317 }
318
319 (*merge_cp_p)->name_and_type_at_put(*merge_cp_length_p,
320 new_name_ref_i, new_signature_ref_i);
321 if (scratch_i != *merge_cp_length_p) {
322 // The new entry in *merge_cp_p is at a different index than
323 // the new entry in scratch_cp so we need to map the index values.
324 map_index(scratch_cp, scratch_i, *merge_cp_length_p);
325 }
326 (*merge_cp_length_p)++;
327 } break;
328
329 // this is a double-indirect CP entry so it needs special handling
330 case JVM_CONSTANT_Fieldref: // fall through
331 case JVM_CONSTANT_InterfaceMethodref: // fall through
332 case JVM_CONSTANT_Methodref:
333 {
334 int klass_ref_i = scratch_cp->uncached_klass_ref_index_at(scratch_i);
335 int new_klass_ref_i = 0;
336 bool match = (klass_ref_i < *merge_cp_length_p) &&
337 scratch_cp->compare_entry_to(klass_ref_i, *merge_cp_p, klass_ref_i,
338 THREAD);
339 if (!match) {
340 // forward reference in *merge_cp_p or not a direct match
341
342 int found_i = scratch_cp->find_matching_entry(klass_ref_i, *merge_cp_p,
343 THREAD);
344 if (found_i != 0) {
345 guarantee(found_i != klass_ref_i,
346 "compare_entry_to() and find_matching_entry() do not agree");
347
348 // Found a matching entry somewhere else in *merge_cp_p so
349 // just need a mapping entry.
350 new_klass_ref_i = found_i;
351 map_index(scratch_cp, klass_ref_i, found_i);
352 } else {
353 // no match found so we have to append this entry to *merge_cp_p
354 append_entry(scratch_cp, klass_ref_i, merge_cp_p, merge_cp_length_p,
355 THREAD);
356 // The above call to append_entry() can only append one entry
357 // so the post call query of *merge_cp_length_p is only for
358 // the sake of consistency. Without the optimization where we
359 // use JVM_CONSTANT_UnresolvedClass, then up to two entries
360 // could be appended.
361 new_klass_ref_i = *merge_cp_length_p - 1;
362 }
363 }
364
365 int name_and_type_ref_i =
366 scratch_cp->uncached_name_and_type_ref_index_at(scratch_i);
367 int new_name_and_type_ref_i = 0;
368 match = (name_and_type_ref_i < *merge_cp_length_p) &&
369 scratch_cp->compare_entry_to(name_and_type_ref_i, *merge_cp_p,
370 name_and_type_ref_i, THREAD);
371 if (!match) {
372 // forward reference in *merge_cp_p or not a direct match
373
374 int found_i = scratch_cp->find_matching_entry(name_and_type_ref_i,
375 *merge_cp_p, THREAD);
376 if (found_i != 0) {
377 guarantee(found_i != name_and_type_ref_i,
378 "compare_entry_to() and find_matching_entry() do not agree");
379
380 // Found a matching entry somewhere else in *merge_cp_p so
381 // just need a mapping entry.
382 new_name_and_type_ref_i = found_i;
383 map_index(scratch_cp, name_and_type_ref_i, found_i);
384 } else {
385 // no match found so we have to append this entry to *merge_cp_p
386 append_entry(scratch_cp, name_and_type_ref_i, merge_cp_p,
387 merge_cp_length_p, THREAD);
388 // The above call to append_entry() can append more than
389 // one entry so the post call query of *merge_cp_length_p
390 // is required in order to get the right index for the
391 // JVM_CONSTANT_NameAndType entry.
392 new_name_and_type_ref_i = *merge_cp_length_p - 1;
393 }
394 }
395
396 // If the referenced entries already exist in *merge_cp_p, then
397 // both new_klass_ref_i and new_name_and_type_ref_i will both be
398 // 0. In that case, all we are appending is the current entry.
399 if (new_klass_ref_i == 0) {
400 new_klass_ref_i = klass_ref_i;
401 }
402 if (new_name_and_type_ref_i == 0) {
403 new_name_and_type_ref_i = name_and_type_ref_i;
404 }
405
406 const char *entry_name;
407 switch (scratch_cp->tag_at(scratch_i).value()) {
408 case JVM_CONSTANT_Fieldref:
409 entry_name = "Fieldref";
410 (*merge_cp_p)->field_at_put(*merge_cp_length_p, new_klass_ref_i,
411 new_name_and_type_ref_i);
412 break;
413 case JVM_CONSTANT_InterfaceMethodref:
414 entry_name = "IFMethodref";
415 (*merge_cp_p)->interface_method_at_put(*merge_cp_length_p,
416 new_klass_ref_i, new_name_and_type_ref_i);
417 break;
418 case JVM_CONSTANT_Methodref:
419 entry_name = "Methodref";
420 (*merge_cp_p)->method_at_put(*merge_cp_length_p, new_klass_ref_i,
421 new_name_and_type_ref_i);
422 break;
423 default:
424 guarantee(false, "bad switch");
425 break;
426 }
427
428 if (klass_ref_i != new_klass_ref_i) {
429 RC_TRACE(0x00080000, ("%s entry@%d class_index changed: %d to %d",
430 entry_name, *merge_cp_length_p, klass_ref_i, new_klass_ref_i));
431 }
432 if (name_and_type_ref_i != new_name_and_type_ref_i) {
433 RC_TRACE(0x00080000,
434 ("%s entry@%d name_and_type_index changed: %d to %d",
435 entry_name, *merge_cp_length_p, name_and_type_ref_i,
436 new_name_and_type_ref_i));
437 }
438
439 if (scratch_i != *merge_cp_length_p) {
440 // The new entry in *merge_cp_p is at a different index than
441 // the new entry in scratch_cp so we need to map the index values.
442 map_index(scratch_cp, scratch_i, *merge_cp_length_p);
443 }
444 (*merge_cp_length_p)++;
445 } break;
446
447 // At this stage, Class or UnresolvedClass could be here, but not
448 // ClassIndex
449 case JVM_CONSTANT_ClassIndex: // fall through
450
451 // Invalid is used as the tag for the second constant pool entry
452 // occupied by JVM_CONSTANT_Double or JVM_CONSTANT_Long. It should
453 // not be seen by itself.
454 case JVM_CONSTANT_Invalid: // fall through
455
456 // At this stage, String or UnresolvedString could be here, but not
457 // StringIndex
458 case JVM_CONSTANT_StringIndex: // fall through
459
460 // At this stage JVM_CONSTANT_UnresolvedClassInError should not be
461 // here
462 case JVM_CONSTANT_UnresolvedClassInError: // fall through
463
464 default:
465 {
466 // leave a breadcrumb
467 jbyte bad_value = scratch_cp->tag_at(scratch_i).value();
468 ShouldNotReachHere();
469 } break;
470 } // end switch tag value
471 } // end append_entry()
472
473
474 void VM_RedefineClasses::swap_all_method_annotations(int i, int j, instanceKlassHandle scratch_class) {
475 typeArrayOop save;
476
477 save = scratch_class->get_method_annotations_of(i);
478 scratch_class->set_method_annotations_of(i, scratch_class->get_method_annotations_of(j));
479 scratch_class->set_method_annotations_of(j, save);
480
481 save = scratch_class->get_method_parameter_annotations_of(i);
482 scratch_class->set_method_parameter_annotations_of(i, scratch_class->get_method_parameter_annotations_of(j));
483 scratch_class->set_method_parameter_annotations_of(j, save);
484
485 save = scratch_class->get_method_default_annotations_of(i);
486 scratch_class->set_method_default_annotations_of(i, scratch_class->get_method_default_annotations_of(j));
487 scratch_class->set_method_default_annotations_of(j, save);
488 }
489
490
491 jvmtiError VM_RedefineClasses::compare_and_normalize_class_versions(
492 instanceKlassHandle the_class,
493 instanceKlassHandle scratch_class) {
494 int i;
495
496 // Check superclasses, or rather their names, since superclasses themselves can be
497 // requested to replace.
498 // Check for NULL superclass first since this might be java.lang.Object
499 if (the_class->super() != scratch_class->super() &&
500 (the_class->super() == NULL || scratch_class->super() == NULL ||
501 Klass::cast(the_class->super())->name() !=
502 Klass::cast(scratch_class->super())->name())) {
503 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_HIERARCHY_CHANGED;
504 }
505
506 // Check if the number, names and order of directly implemented interfaces are the same.
507 // I think in principle we should just check if the sets of names of directly implemented
508 // interfaces are the same, i.e. the order of declaration (which, however, if changed in the
509 // .java file, also changes in .class file) should not matter. However, comparing sets is
510 // technically a bit more difficult, and, more importantly, I am not sure at present that the
511 // order of interfaces does not matter on the implementation level, i.e. that the VM does not
512 // rely on it somewhere.
513 objArrayOop k_interfaces = the_class->local_interfaces();
514 objArrayOop k_new_interfaces = scratch_class->local_interfaces();
515 int n_intfs = k_interfaces->length();
516 if (n_intfs != k_new_interfaces->length()) {
517 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_HIERARCHY_CHANGED;
518 }
519 for (i = 0; i < n_intfs; i++) {
520 if (Klass::cast((klassOop) k_interfaces->obj_at(i))->name() !=
521 Klass::cast((klassOop) k_new_interfaces->obj_at(i))->name()) {
522 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_HIERARCHY_CHANGED;
523 }
524 }
525
526 // Check whether class is in the error init state.
527 if (the_class->is_in_error_state()) {
528 // TBD #5057930: special error code is needed in 1.6
529 return JVMTI_ERROR_INVALID_CLASS;
530 }
531
532 // Check whether class modifiers are the same.
533 jushort old_flags = (jushort) the_class->access_flags().get_flags();
534 jushort new_flags = (jushort) scratch_class->access_flags().get_flags();
535 if (old_flags != new_flags) {
536 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_CLASS_MODIFIERS_CHANGED;
537 }
538
539 // Check if the number, names, types and order of fields declared in these classes
540 // are the same.
541 typeArrayOop k_old_fields = the_class->fields();
542 typeArrayOop k_new_fields = scratch_class->fields();
543 int n_fields = k_old_fields->length();
544 if (n_fields != k_new_fields->length()) {
545 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_SCHEMA_CHANGED;
546 }
547
548 for (i = 0; i < n_fields; i += instanceKlass::next_offset) {
549 // access
550 old_flags = k_old_fields->ushort_at(i + instanceKlass::access_flags_offset);
551 new_flags = k_new_fields->ushort_at(i + instanceKlass::access_flags_offset);
552 if ((old_flags ^ new_flags) & JVM_RECOGNIZED_FIELD_MODIFIERS) {
553 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_SCHEMA_CHANGED;
554 }
555 // offset
556 if (k_old_fields->short_at(i + instanceKlass::low_offset) !=
557 k_new_fields->short_at(i + instanceKlass::low_offset) ||
558 k_old_fields->short_at(i + instanceKlass::high_offset) !=
559 k_new_fields->short_at(i + instanceKlass::high_offset)) {
560 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_SCHEMA_CHANGED;
561 }
562 // name and signature
563 jshort name_index = k_old_fields->short_at(i + instanceKlass::name_index_offset);
564 jshort sig_index = k_old_fields->short_at(i +instanceKlass::signature_index_offset);
565 symbolOop name_sym1 = the_class->constants()->symbol_at(name_index);
566 symbolOop sig_sym1 = the_class->constants()->symbol_at(sig_index);
567 name_index = k_new_fields->short_at(i + instanceKlass::name_index_offset);
568 sig_index = k_new_fields->short_at(i + instanceKlass::signature_index_offset);
569 symbolOop name_sym2 = scratch_class->constants()->symbol_at(name_index);
570 symbolOop sig_sym2 = scratch_class->constants()->symbol_at(sig_index);
571 if (name_sym1 != name_sym2 || sig_sym1 != sig_sym2) {
572 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_SCHEMA_CHANGED;
573 }
574 }
575
576 // Do a parallel walk through the old and new methods. Detect
577 // cases where they match (exist in both), have been added in
578 // the new methods, or have been deleted (exist only in the
579 // old methods). The class file parser places methods in order
580 // by method name, but does not order overloaded methods by
581 // signature. In order to determine what fate befell the methods,
582 // this code places the overloaded new methods that have matching
583 // old methods in the same order as the old methods and places
584 // new overloaded methods at the end of overloaded methods of
585 // that name. The code for this order normalization is adapted
586 // from the algorithm used in instanceKlass::find_method().
587 // Since we are swapping out of order entries as we find them,
588 // we only have to search forward through the overloaded methods.
589 // Methods which are added and have the same name as an existing
590 // method (but different signature) will be put at the end of
591 // the methods with that name, and the name mismatch code will
592 // handle them.
593 objArrayHandle k_old_methods(the_class->methods());
594 objArrayHandle k_new_methods(scratch_class->methods());
595 int n_old_methods = k_old_methods->length();
596 int n_new_methods = k_new_methods->length();
597
598 int ni = 0;
599 int oi = 0;
600 while (true) {
601 methodOop k_old_method;
602 methodOop k_new_method;
603 enum { matched, added, deleted, undetermined } method_was = undetermined;
604
605 if (oi >= n_old_methods) {
606 if (ni >= n_new_methods) {
607 break; // we've looked at everything, done
608 }
609 // New method at the end
610 k_new_method = (methodOop) k_new_methods->obj_at(ni);
611 method_was = added;
612 } else if (ni >= n_new_methods) {
613 // Old method, at the end, is deleted
614 k_old_method = (methodOop) k_old_methods->obj_at(oi);
615 method_was = deleted;
616 } else {
617 // There are more methods in both the old and new lists
618 k_old_method = (methodOop) k_old_methods->obj_at(oi);
619 k_new_method = (methodOop) k_new_methods->obj_at(ni);
620 if (k_old_method->name() != k_new_method->name()) {
621 // Methods are sorted by method name, so a mismatch means added
622 // or deleted
623 if (k_old_method->name()->fast_compare(k_new_method->name()) > 0) {
624 method_was = added;
625 } else {
626 method_was = deleted;
627 }
628 } else if (k_old_method->signature() == k_new_method->signature()) {
629 // Both the name and signature match
630 method_was = matched;
631 } else {
632 // The name matches, but the signature doesn't, which means we have to
633 // search forward through the new overloaded methods.
634 int nj; // outside the loop for post-loop check
635 for (nj = ni + 1; nj < n_new_methods; nj++) {
636 methodOop m = (methodOop)k_new_methods->obj_at(nj);
637 if (k_old_method->name() != m->name()) {
638 // reached another method name so no more overloaded methods
639 method_was = deleted;
640 break;
641 }
642 if (k_old_method->signature() == m->signature()) {
643 // found a match so swap the methods
644 k_new_methods->obj_at_put(ni, m);
645 k_new_methods->obj_at_put(nj, k_new_method);
646 k_new_method = m;
647 method_was = matched;
648 break;
649 }
650 }
651
652 if (nj >= n_new_methods) {
653 // reached the end without a match; so method was deleted
654 method_was = deleted;
655 }
656 }
657 }
658
659 switch (method_was) {
660 case matched:
661 // methods match, be sure modifiers do too
662 old_flags = (jushort) k_old_method->access_flags().get_flags();
663 new_flags = (jushort) k_new_method->access_flags().get_flags();
664 if ((old_flags ^ new_flags) & ~(JVM_ACC_NATIVE)) {
665 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_METHOD_MODIFIERS_CHANGED;
666 }
667 {
668 u2 new_num = k_new_method->method_idnum();
669 u2 old_num = k_old_method->method_idnum();
670 if (new_num != old_num) {
671 methodOop idnum_owner = scratch_class->method_with_idnum(old_num);
672 if (idnum_owner != NULL) {
673 // There is already a method assigned this idnum -- switch them
674 idnum_owner->set_method_idnum(new_num);
675 }
676 k_new_method->set_method_idnum(old_num);
677 swap_all_method_annotations(old_num, new_num, scratch_class);
678 }
679 }
680 RC_TRACE(0x00008000, ("Method matched: new: %s [%d] == old: %s [%d]",
681 k_new_method->name_and_sig_as_C_string(), ni,
682 k_old_method->name_and_sig_as_C_string(), oi));
683 // advance to next pair of methods
684 ++oi;
685 ++ni;
686 break;
687 case added:
688 // method added, see if it is OK
689 new_flags = (jushort) k_new_method->access_flags().get_flags();
690 if ((new_flags & JVM_ACC_PRIVATE) == 0
691 // hack: private should be treated as final, but alas
692 || (new_flags & (JVM_ACC_FINAL|JVM_ACC_STATIC)) == 0
693 ) {
694 // new methods must be private
695 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_METHOD_ADDED;
696 }
697 {
698 u2 num = the_class->next_method_idnum();
699 if (num == constMethodOopDesc::UNSET_IDNUM) {
700 // cannot add any more methods
701 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_METHOD_ADDED;
702 }
703 u2 new_num = k_new_method->method_idnum();
704 methodOop idnum_owner = scratch_class->method_with_idnum(num);
705 if (idnum_owner != NULL) {
706 // There is already a method assigned this idnum -- switch them
707 idnum_owner->set_method_idnum(new_num);
708 }
709 k_new_method->set_method_idnum(num);
710 swap_all_method_annotations(new_num, num, scratch_class);
711 }
712 RC_TRACE(0x00008000, ("Method added: new: %s [%d]",
713 k_new_method->name_and_sig_as_C_string(), ni));
714 ++ni; // advance to next new method
715 break;
716 case deleted:
717 // method deleted, see if it is OK
718 old_flags = (jushort) k_old_method->access_flags().get_flags();
719 if ((old_flags & JVM_ACC_PRIVATE) == 0
720 // hack: private should be treated as final, but alas
721 || (old_flags & (JVM_ACC_FINAL|JVM_ACC_STATIC)) == 0
722 ) {
723 // deleted methods must be private
724 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_METHOD_DELETED;
725 }
726 RC_TRACE(0x00008000, ("Method deleted: old: %s [%d]",
727 k_old_method->name_and_sig_as_C_string(), oi));
728 ++oi; // advance to next old method
729 break;
730 default:
731 ShouldNotReachHere();
732 }
733 }
734
735 return JVMTI_ERROR_NONE;
736 }
737
738
739 // Find new constant pool index value for old constant pool index value
740 // by seaching the index map. Returns zero (0) if there is no mapped
741 // value for the old constant pool index.
742 int VM_RedefineClasses::find_new_index(int old_index) {
743 if (_index_map_count == 0) {
744 // map is empty so nothing can be found
745 return 0;
746 }
747
748 if (old_index < 1 || old_index >= _index_map_p->length()) {
749 // The old_index is out of range so it is not mapped. This should
750 // not happen in regular constant pool merging use, but it can
751 // happen if a corrupt annotation is processed.
752 return 0;
753 }
754
755 int value = _index_map_p->at(old_index);
756 if (value == -1) {
757 // the old_index is not mapped
758 return 0;
759 }
760
761 return value;
762 } // end find_new_index()
763
764
765 // Returns true if the current mismatch is due to a resolved/unresolved
766 // class pair. Otherwise, returns false.
767 bool VM_RedefineClasses::is_unresolved_class_mismatch(constantPoolHandle cp1,
768 int index1, constantPoolHandle cp2, int index2) {
769
770 jbyte t1 = cp1->tag_at(index1).value();
771 if (t1 != JVM_CONSTANT_Class && t1 != JVM_CONSTANT_UnresolvedClass) {
772 return false; // wrong entry type; not our special case
773 }
774
775 jbyte t2 = cp2->tag_at(index2).value();
776 if (t2 != JVM_CONSTANT_Class && t2 != JVM_CONSTANT_UnresolvedClass) {
777 return false; // wrong entry type; not our special case
778 }
779
780 if (t1 == t2) {
781 return false; // not a mismatch; not our special case
782 }
783
784 char *s1 = cp1->klass_name_at(index1)->as_C_string();
785 char *s2 = cp2->klass_name_at(index2)->as_C_string();
786 if (strcmp(s1, s2) != 0) {
787 return false; // strings don't match; not our special case
788 }
789
790 return true; // made it through the gauntlet; this is our special case
791 } // end is_unresolved_class_mismatch()
792
793
794 // Returns true if the current mismatch is due to a resolved/unresolved
795 // string pair. Otherwise, returns false.
796 bool VM_RedefineClasses::is_unresolved_string_mismatch(constantPoolHandle cp1,
797 int index1, constantPoolHandle cp2, int index2) {
798
799 jbyte t1 = cp1->tag_at(index1).value();
800 if (t1 != JVM_CONSTANT_String && t1 != JVM_CONSTANT_UnresolvedString) {
801 return false; // wrong entry type; not our special case
802 }
803
804 jbyte t2 = cp2->tag_at(index2).value();
805 if (t2 != JVM_CONSTANT_String && t2 != JVM_CONSTANT_UnresolvedString) {
806 return false; // wrong entry type; not our special case
807 }
808
809 if (t1 == t2) {
810 return false; // not a mismatch; not our special case
811 }
812
813 char *s1 = cp1->string_at_noresolve(index1);
814 char *s2 = cp2->string_at_noresolve(index2);
815 if (strcmp(s1, s2) != 0) {
816 return false; // strings don't match; not our special case
817 }
818
819 return true; // made it through the gauntlet; this is our special case
820 } // end is_unresolved_string_mismatch()
821
822
823 jvmtiError VM_RedefineClasses::load_new_class_versions(TRAPS) {
824 // For consistency allocate memory using os::malloc wrapper.
825 _scratch_classes = (instanceKlassHandle *)
826 os::malloc(sizeof(instanceKlassHandle) * _class_count);
827 if (_scratch_classes == NULL) {
828 return JVMTI_ERROR_OUT_OF_MEMORY;
829 }
830
831 ResourceMark rm(THREAD);
832
833 JvmtiThreadState *state = JvmtiThreadState::state_for(JavaThread::current());
834 // state can only be NULL if the current thread is exiting which
835 // should not happen since we're trying to do a RedefineClasses
836 guarantee(state != NULL, "exiting thread calling load_new_class_versions");
837 for (int i = 0; i < _class_count; i++) {
838 oop mirror = JNIHandles::resolve_non_null(_class_defs[i].klass);
839 // classes for primitives cannot be redefined
840 if (!is_modifiable_class(mirror)) {
841 return JVMTI_ERROR_UNMODIFIABLE_CLASS;
842 }
843 klassOop the_class_oop = java_lang_Class::as_klassOop(mirror);
844 instanceKlassHandle the_class = instanceKlassHandle(THREAD, the_class_oop);
845 symbolHandle the_class_sym = symbolHandle(THREAD, the_class->name());
846
847 // RC_TRACE_WITH_THREAD macro has an embedded ResourceMark
848 RC_TRACE_WITH_THREAD(0x00000001, THREAD,
849 ("loading name=%s (avail_mem=" UINT64_FORMAT "K)",
850 the_class->external_name(), os::available_memory() >> 10));
851
852 ClassFileStream st((u1*) _class_defs[i].class_bytes,
853 _class_defs[i].class_byte_count, (char *)"__VM_RedefineClasses__");
854
855 // Parse the stream.
856 Handle the_class_loader(THREAD, the_class->class_loader());
857 Handle protection_domain(THREAD, the_class->protection_domain());
858 // Set redefined class handle in JvmtiThreadState class.
859 // This redefined class is sent to agent event handler for class file
860 // load hook event.
861 state->set_class_being_redefined(&the_class, _class_load_kind);
862
863 klassOop k = SystemDictionary::parse_stream(the_class_sym,
864 the_class_loader,
865 protection_domain,
866 &st,
867 THREAD);
868 // Clear class_being_redefined just to be sure.
869 state->clear_class_being_redefined();
870
871 // TODO: if this is retransform, and nothing changed we can skip it
872
873 instanceKlassHandle scratch_class (THREAD, k);
874
875 if (HAS_PENDING_EXCEPTION) {
876 symbolOop ex_name = PENDING_EXCEPTION->klass()->klass_part()->name();
877 // RC_TRACE_WITH_THREAD macro has an embedded ResourceMark
878 RC_TRACE_WITH_THREAD(0x00000002, THREAD, ("parse_stream exception: '%s'",
879 ex_name->as_C_string()));
880 CLEAR_PENDING_EXCEPTION;
881
882 if (ex_name == vmSymbols::java_lang_UnsupportedClassVersionError()) {
883 return JVMTI_ERROR_UNSUPPORTED_VERSION;
884 } else if (ex_name == vmSymbols::java_lang_ClassFormatError()) {
885 return JVMTI_ERROR_INVALID_CLASS_FORMAT;
886 } else if (ex_name == vmSymbols::java_lang_ClassCircularityError()) {
887 return JVMTI_ERROR_CIRCULAR_CLASS_DEFINITION;
888 } else if (ex_name == vmSymbols::java_lang_NoClassDefFoundError()) {
889 // The message will be "XXX (wrong name: YYY)"
890 return JVMTI_ERROR_NAMES_DONT_MATCH;
891 } else if (ex_name == vmSymbols::java_lang_OutOfMemoryError()) {
892 return JVMTI_ERROR_OUT_OF_MEMORY;
893 } else { // Just in case more exceptions can be thrown..
894 return JVMTI_ERROR_FAILS_VERIFICATION;
895 }
896 }
897
898 // Ensure class is linked before redefine
899 if (!the_class->is_linked()) {
900 the_class->link_class(THREAD);
901 if (HAS_PENDING_EXCEPTION) {
902 symbolOop ex_name = PENDING_EXCEPTION->klass()->klass_part()->name();
903 // RC_TRACE_WITH_THREAD macro has an embedded ResourceMark
904 RC_TRACE_WITH_THREAD(0x00000002, THREAD, ("link_class exception: '%s'",
905 ex_name->as_C_string()));
906 CLEAR_PENDING_EXCEPTION;
907 if (ex_name == vmSymbols::java_lang_OutOfMemoryError()) {
908 return JVMTI_ERROR_OUT_OF_MEMORY;
909 } else {
910 return JVMTI_ERROR_INTERNAL;
911 }
912 }
913 }
914
915 // Do the validity checks in compare_and_normalize_class_versions()
916 // before verifying the byte codes. By doing these checks first, we
917 // limit the number of functions that require redirection from
918 // the_class to scratch_class. In particular, we don't have to
919 // modify JNI GetSuperclass() and thus won't change its performance.
920 jvmtiError res = compare_and_normalize_class_versions(the_class,
921 scratch_class);
922 if (res != JVMTI_ERROR_NONE) {
923 return res;
924 }
925
926 // verify what the caller passed us
927 {
928 // The bug 6214132 caused the verification to fail.
929 // Information about the_class and scratch_class is temporarily
930 // recorded into jvmtiThreadState. This data is used to redirect
931 // the_class to scratch_class in the JVM_* functions called by the
932 // verifier. Please, refer to jvmtiThreadState.hpp for the detailed
933 // description.
934 RedefineVerifyMark rvm(&the_class, &scratch_class, state);
935 Verifier::verify(
936 scratch_class, Verifier::ThrowException, true, THREAD);
937 }
938
939 if (HAS_PENDING_EXCEPTION) {
940 symbolOop ex_name = PENDING_EXCEPTION->klass()->klass_part()->name();
941 // RC_TRACE_WITH_THREAD macro has an embedded ResourceMark
942 RC_TRACE_WITH_THREAD(0x00000002, THREAD,
943 ("verify_byte_codes exception: '%s'", ex_name->as_C_string()));
944 CLEAR_PENDING_EXCEPTION;
945 if (ex_name == vmSymbols::java_lang_OutOfMemoryError()) {
946 return JVMTI_ERROR_OUT_OF_MEMORY;
947 } else {
948 // tell the caller the bytecodes are bad
949 return JVMTI_ERROR_FAILS_VERIFICATION;
950 }
951 }
952
953 res = merge_cp_and_rewrite(the_class, scratch_class, THREAD);
954 if (res != JVMTI_ERROR_NONE) {
955 return res;
956 }
957
958 if (VerifyMergedCPBytecodes) {
959 // verify what we have done during constant pool merging
960 {
961 RedefineVerifyMark rvm(&the_class, &scratch_class, state);
962 Verifier::verify(scratch_class, Verifier::ThrowException, true, THREAD);
963 }
964
965 if (HAS_PENDING_EXCEPTION) {
966 symbolOop ex_name = PENDING_EXCEPTION->klass()->klass_part()->name();
967 // RC_TRACE_WITH_THREAD macro has an embedded ResourceMark
968 RC_TRACE_WITH_THREAD(0x00000002, THREAD,
969 ("verify_byte_codes post merge-CP exception: '%s'",
970 ex_name->as_C_string()));
971 CLEAR_PENDING_EXCEPTION;
972 if (ex_name == vmSymbols::java_lang_OutOfMemoryError()) {
973 return JVMTI_ERROR_OUT_OF_MEMORY;
974 } else {
975 // tell the caller that constant pool merging screwed up
976 return JVMTI_ERROR_INTERNAL;
977 }
978 }
979 }
980
981 Rewriter::rewrite(scratch_class, THREAD);
982 if (HAS_PENDING_EXCEPTION) {
983 symbolOop ex_name = PENDING_EXCEPTION->klass()->klass_part()->name();
984 CLEAR_PENDING_EXCEPTION;
985 if (ex_name == vmSymbols::java_lang_OutOfMemoryError()) {
986 return JVMTI_ERROR_OUT_OF_MEMORY;
987 } else {
988 return JVMTI_ERROR_INTERNAL;
989 }
990 }
991
992 _scratch_classes[i] = scratch_class;
993
994 // RC_TRACE_WITH_THREAD macro has an embedded ResourceMark
995 RC_TRACE_WITH_THREAD(0x00000001, THREAD,
996 ("loaded name=%s (avail_mem=" UINT64_FORMAT "K)",
997 the_class->external_name(), os::available_memory() >> 10));
998 }
999
1000 return JVMTI_ERROR_NONE;
1001 }
1002
1003
1004 // Map old_index to new_index as needed. scratch_cp is only needed
1005 // for RC_TRACE() calls.
1006 void VM_RedefineClasses::map_index(constantPoolHandle scratch_cp,
1007 int old_index, int new_index) {
1008 if (find_new_index(old_index) != 0) {
1009 // old_index is already mapped
1010 return;
1011 }
1012
1013 if (old_index == new_index) {
1014 // no mapping is needed
1015 return;
1016 }
1017
1018 _index_map_p->at_put(old_index, new_index);
1019 _index_map_count++;
1020
1021 RC_TRACE(0x00040000, ("mapped tag %d at index %d to %d",
1022 scratch_cp->tag_at(old_index).value(), old_index, new_index));
1023 } // end map_index()
1024
1025
1026 // Merge old_cp and scratch_cp and return the results of the merge via
1027 // merge_cp_p. The number of entries in *merge_cp_p is returned via
1028 // merge_cp_length_p. The entries in old_cp occupy the same locations
1029 // in *merge_cp_p. Also creates a map of indices from entries in
1030 // scratch_cp to the corresponding entry in *merge_cp_p. Index map
1031 // entries are only created for entries in scratch_cp that occupy a
1032 // different location in *merged_cp_p.
1033 bool VM_RedefineClasses::merge_constant_pools(constantPoolHandle old_cp,
1034 constantPoolHandle scratch_cp, constantPoolHandle *merge_cp_p,
1035 int *merge_cp_length_p, TRAPS) {
1036
1037 if (merge_cp_p == NULL) {
1038 assert(false, "caller must provide scatch constantPool");
1039 return false; // robustness
1040 }
1041 if (merge_cp_length_p == NULL) {
1042 assert(false, "caller must provide scatch CP length");
1043 return false; // robustness
1044 }
1045 // Worst case we need old_cp->length() + scratch_cp()->length(),
1046 // but the caller might be smart so make sure we have at least
1047 // the minimum.
1048 if ((*merge_cp_p)->length() < old_cp->length()) {
1049 assert(false, "merge area too small");
1050 return false; // robustness
1051 }
1052
1053 RC_TRACE_WITH_THREAD(0x00010000, THREAD,
1054 ("old_cp_len=%d, scratch_cp_len=%d", old_cp->length(),
1055 scratch_cp->length()));
1056
1057 {
1058 // Pass 0:
1059 // The old_cp is copied to *merge_cp_p; this means that any code
1060 // using old_cp does not have to change. This work looks like a
1061 // perfect fit for constantPoolOop::copy_cp_to(), but we need to
1062 // handle one special case:
1063 // - revert JVM_CONSTANT_Class to JVM_CONSTANT_UnresolvedClass
1064 // This will make verification happy.
1065
1066 int old_i; // index into old_cp
1067
1068 // index zero (0) is not used in constantPools
1069 for (old_i = 1; old_i < old_cp->length(); old_i++) {
1070 // leave debugging crumb
1071 jbyte old_tag = old_cp->tag_at(old_i).value();
1072 switch (old_tag) {
1073 case JVM_CONSTANT_Class:
1074 // revert the copy to JVM_CONSTANT_UnresolvedClass
1075 (*merge_cp_p)->unresolved_klass_at_put(old_i,
1076 old_cp->klass_name_at(old_i));
1077 break;
1078
1079 case JVM_CONSTANT_Double:
1080 case JVM_CONSTANT_Long:
1081 // just copy the entry to *merge_cp_p, but double and long take
1082 // two constant pool entries
1083 old_cp->copy_entry_to(old_i, *merge_cp_p, old_i, CHECK_0);
1084 old_i++;
1085 break;
1086
1087 default:
1088 // just copy the entry to *merge_cp_p
1089 old_cp->copy_entry_to(old_i, *merge_cp_p, old_i, CHECK_0);
1090 break;
1091 }
1092 } // end for each old_cp entry
1093
1094 // We don't need to sanity check that *merge_cp_length_p is within
1095 // *merge_cp_p bounds since we have the minimum on-entry check above.
1096 (*merge_cp_length_p) = old_i;
1097 }
1098
1099 // merge_cp_len should be the same as old_cp->length() at this point
1100 // so this trace message is really a "warm-and-breathing" message.
1101 RC_TRACE_WITH_THREAD(0x00020000, THREAD,
1102 ("after pass 0: merge_cp_len=%d", *merge_cp_length_p));
1103
1104 int scratch_i; // index into scratch_cp
1105 {
1106 // Pass 1a:
1107 // Compare scratch_cp entries to the old_cp entries that we have
1108 // already copied to *merge_cp_p. In this pass, we are eliminating
1109 // exact duplicates (matching entry at same index) so we only
1110 // compare entries in the common indice range.
1111 int increment = 1;
1112 int pass1a_length = MIN2(old_cp->length(), scratch_cp->length());
1113 for (scratch_i = 1; scratch_i < pass1a_length; scratch_i += increment) {
1114 switch (scratch_cp->tag_at(scratch_i).value()) {
1115 case JVM_CONSTANT_Double:
1116 case JVM_CONSTANT_Long:
1117 // double and long take two constant pool entries
1118 increment = 2;
1119 break;
1120
1121 default:
1122 increment = 1;
1123 break;
1124 }
1125
1126 bool match = scratch_cp->compare_entry_to(scratch_i, *merge_cp_p,
1127 scratch_i, CHECK_0);
1128 if (match) {
1129 // found a match at the same index so nothing more to do
1130 continue;
1131 } else if (is_unresolved_class_mismatch(scratch_cp, scratch_i,
1132 *merge_cp_p, scratch_i)) {
1133 // The mismatch in compare_entry_to() above is because of a
1134 // resolved versus unresolved class entry at the same index
1135 // with the same string value. Since Pass 0 reverted any
1136 // class entries to unresolved class entries in *merge_cp_p,
1137 // we go with the unresolved class entry.
1138 continue;
1139 } else if (is_unresolved_string_mismatch(scratch_cp, scratch_i,
1140 *merge_cp_p, scratch_i)) {
1141 // The mismatch in compare_entry_to() above is because of a
1142 // resolved versus unresolved string entry at the same index
1143 // with the same string value. We can live with whichever
1144 // happens to be at scratch_i in *merge_cp_p.
1145 continue;
1146 }
1147
1148 int found_i = scratch_cp->find_matching_entry(scratch_i, *merge_cp_p,
1149 CHECK_0);
1150 if (found_i != 0) {
1151 guarantee(found_i != scratch_i,
1152 "compare_entry_to() and find_matching_entry() do not agree");
1153
1154 // Found a matching entry somewhere else in *merge_cp_p so
1155 // just need a mapping entry.
1156 map_index(scratch_cp, scratch_i, found_i);
1157 continue;
1158 }
1159
1160 // The find_matching_entry() call above could fail to find a match
1161 // due to a resolved versus unresolved class or string entry situation
1162 // like we solved above with the is_unresolved_*_mismatch() calls.
1163 // However, we would have to call is_unresolved_*_mismatch() over
1164 // all of *merge_cp_p (potentially) and that doesn't seem to be
1165 // worth the time.
1166
1167 // No match found so we have to append this entry and any unique
1168 // referenced entries to *merge_cp_p.
1169 append_entry(scratch_cp, scratch_i, merge_cp_p, merge_cp_length_p,
1170 CHECK_0);
1171 }
1172 }
1173
1174 RC_TRACE_WITH_THREAD(0x00020000, THREAD,
1175 ("after pass 1a: merge_cp_len=%d, scratch_i=%d, index_map_len=%d",
1176 *merge_cp_length_p, scratch_i, _index_map_count));
1177
1178 if (scratch_i < scratch_cp->length()) {
1179 // Pass 1b:
1180 // old_cp is smaller than scratch_cp so there are entries in
1181 // scratch_cp that we have not yet processed. We take care of
1182 // those now.
1183 int increment = 1;
1184 for (; scratch_i < scratch_cp->length(); scratch_i += increment) {
1185 switch (scratch_cp->tag_at(scratch_i).value()) {
1186 case JVM_CONSTANT_Double:
1187 case JVM_CONSTANT_Long:
1188 // double and long take two constant pool entries
1189 increment = 2;
1190 break;
1191
1192 default:
1193 increment = 1;
1194 break;
1195 }
1196
1197 int found_i =
1198 scratch_cp->find_matching_entry(scratch_i, *merge_cp_p, CHECK_0);
1199 if (found_i != 0) {
1200 // Found a matching entry somewhere else in *merge_cp_p so
1201 // just need a mapping entry.
1202 map_index(scratch_cp, scratch_i, found_i);
1203 continue;
1204 }
1205
1206 // No match found so we have to append this entry and any unique
1207 // referenced entries to *merge_cp_p.
1208 append_entry(scratch_cp, scratch_i, merge_cp_p, merge_cp_length_p,
1209 CHECK_0);
1210 }
1211
1212 RC_TRACE_WITH_THREAD(0x00020000, THREAD,
1213 ("after pass 1b: merge_cp_len=%d, scratch_i=%d, index_map_len=%d",
1214 *merge_cp_length_p, scratch_i, _index_map_count));
1215 }
1216
1217 return true;
1218 } // end merge_constant_pools()
1219
1220
1221 // Merge constant pools between the_class and scratch_class and
1222 // potentially rewrite bytecodes in scratch_class to use the merged
1223 // constant pool.
1224 jvmtiError VM_RedefineClasses::merge_cp_and_rewrite(
1225 instanceKlassHandle the_class, instanceKlassHandle scratch_class,
1226 TRAPS) {
1227 // worst case merged constant pool length is old and new combined
1228 int merge_cp_length = the_class->constants()->length()
1229 + scratch_class->constants()->length();
1230
1231 constantPoolHandle old_cp(THREAD, the_class->constants());
1232 constantPoolHandle scratch_cp(THREAD, scratch_class->constants());
1233
1234 // Constant pools are not easily reused so we allocate a new one
1235 // each time.
1236 // merge_cp is created unsafe for concurrent GC processing. It
1237 // should be marked safe before discarding it because, even if
1238 // garbage. If it crosses a card boundary, it may be scanned
1239 // in order to find the start of the first complete object on the card.
1240 constantPoolHandle merge_cp(THREAD,
1241 oopFactory::new_constantPool(merge_cp_length,
1242 methodOopDesc::IsUnsafeConc,
1243 THREAD));
1244 int orig_length = old_cp->orig_length();
1245 if (orig_length == 0) {
1246 // This old_cp is an actual original constant pool. We save
1247 // the original length in the merged constant pool so that
1248 // merge_constant_pools() can be more efficient. If a constant
1249 // pool has a non-zero orig_length() value, then that constant
1250 // pool was created by a merge operation in RedefineClasses.
1251 merge_cp->set_orig_length(old_cp->length());
1252 } else {
1253 // This old_cp is a merged constant pool from a previous
1254 // RedefineClasses() calls so just copy the orig_length()
1255 // value.
1256 merge_cp->set_orig_length(old_cp->orig_length());
1257 }
1258
1259 ResourceMark rm(THREAD);
1260 _index_map_count = 0;
1261 _index_map_p = new intArray(scratch_cp->length(), -1);
1262
1263 bool result = merge_constant_pools(old_cp, scratch_cp, &merge_cp,
1264 &merge_cp_length, THREAD);
1265 if (!result) {
1266 // The merge can fail due to memory allocation failure or due
1267 // to robustness checks.
1268 return JVMTI_ERROR_INTERNAL;
1269 }
1270
1271 RC_TRACE_WITH_THREAD(0x00010000, THREAD,
1272 ("merge_cp_len=%d, index_map_len=%d", merge_cp_length, _index_map_count));
1273
1274 if (_index_map_count == 0) {
1275 // there is nothing to map between the new and merged constant pools
1276
1277 if (old_cp->length() == scratch_cp->length()) {
1278 // The old and new constant pools are the same length and the
1279 // index map is empty. This means that the three constant pools
1280 // are equivalent (but not the same). Unfortunately, the new
1281 // constant pool has not gone through link resolution nor have
1282 // the new class bytecodes gone through constant pool cache
1283 // rewriting so we can't use the old constant pool with the new
1284 // class.
1285
1286 merge_cp()->set_is_conc_safe(true);
1287 merge_cp = constantPoolHandle(); // toss the merged constant pool
1288 } else if (old_cp->length() < scratch_cp->length()) {
1289 // The old constant pool has fewer entries than the new constant
1290 // pool and the index map is empty. This means the new constant
1291 // pool is a superset of the old constant pool. However, the old
1292 // class bytecodes have already gone through constant pool cache
1293 // rewriting so we can't use the new constant pool with the old
1294 // class.
1295
1296 merge_cp()->set_is_conc_safe(true);
1297 merge_cp = constantPoolHandle(); // toss the merged constant pool
1298 } else {
1299 // The old constant pool has more entries than the new constant
1300 // pool and the index map is empty. This means that both the old
1301 // and merged constant pools are supersets of the new constant
1302 // pool.
1303
1304 // Replace the new constant pool with a shrunken copy of the
1305 // merged constant pool; the previous new constant pool will
1306 // get GCed.
1307 set_new_constant_pool(scratch_class, merge_cp, merge_cp_length, true,
1308 THREAD);
1309 // drop local ref to the merged constant pool
1310 merge_cp()->set_is_conc_safe(true);
1311 merge_cp = constantPoolHandle();
1312 }
1313 } else {
1314 if (RC_TRACE_ENABLED(0x00040000)) {
1315 // don't want to loop unless we are tracing
1316 int count = 0;
1317 for (int i = 1; i < _index_map_p->length(); i++) {
1318 int value = _index_map_p->at(i);
1319
1320 if (value != -1) {
1321 RC_TRACE_WITH_THREAD(0x00040000, THREAD,
1322 ("index_map[%d]: old=%d new=%d", count, i, value));
1323 count++;
1324 }
1325 }
1326 }
1327
1328 // We have entries mapped between the new and merged constant pools
1329 // so we have to rewrite some constant pool references.
1330 if (!rewrite_cp_refs(scratch_class, THREAD)) {
1331 return JVMTI_ERROR_INTERNAL;
1332 }
1333
1334 // Replace the new constant pool with a shrunken copy of the
1335 // merged constant pool so now the rewritten bytecodes have
1336 // valid references; the previous new constant pool will get
1337 // GCed.
1338 set_new_constant_pool(scratch_class, merge_cp, merge_cp_length, true,
1339 THREAD);
1340 merge_cp()->set_is_conc_safe(true);
1341 }
1342 assert(old_cp()->is_conc_safe(), "Just checking");
1343 assert(scratch_cp()->is_conc_safe(), "Just checking");
1344
1345 return JVMTI_ERROR_NONE;
1346 } // end merge_cp_and_rewrite()
1347
1348
1349 // Rewrite constant pool references in klass scratch_class.
1350 bool VM_RedefineClasses::rewrite_cp_refs(instanceKlassHandle scratch_class,
1351 TRAPS) {
1352
1353 // rewrite constant pool references in the methods:
1354 if (!rewrite_cp_refs_in_methods(scratch_class, THREAD)) {
1355 // propagate failure back to caller
1356 return false;
1357 }
1358
1359 // rewrite constant pool references in the class_annotations:
1360 if (!rewrite_cp_refs_in_class_annotations(scratch_class, THREAD)) {
1361 // propagate failure back to caller
1362 return false;
1363 }
1364
1365 // rewrite constant pool references in the fields_annotations:
1366 if (!rewrite_cp_refs_in_fields_annotations(scratch_class, THREAD)) {
1367 // propagate failure back to caller
1368 return false;
1369 }
1370
1371 // rewrite constant pool references in the methods_annotations:
1372 if (!rewrite_cp_refs_in_methods_annotations(scratch_class, THREAD)) {
1373 // propagate failure back to caller
1374 return false;
1375 }
1376
1377 // rewrite constant pool references in the methods_parameter_annotations:
1378 if (!rewrite_cp_refs_in_methods_parameter_annotations(scratch_class,
1379 THREAD)) {
1380 // propagate failure back to caller
1381 return false;
1382 }
1383
1384 // rewrite constant pool references in the methods_default_annotations:
1385 if (!rewrite_cp_refs_in_methods_default_annotations(scratch_class,
1386 THREAD)) {
1387 // propagate failure back to caller
1388 return false;
1389 }
1390
1391 return true;
1392 } // end rewrite_cp_refs()
1393
1394
1395 // Rewrite constant pool references in the methods.
1396 bool VM_RedefineClasses::rewrite_cp_refs_in_methods(
1397 instanceKlassHandle scratch_class, TRAPS) {
1398
1399 objArrayHandle methods(THREAD, scratch_class->methods());
1400
1401 if (methods.is_null() || methods->length() == 0) {
1402 // no methods so nothing to do
1403 return true;
1404 }
1405
1406 // rewrite constant pool references in the methods:
1407 for (int i = methods->length() - 1; i >= 0; i--) {
1408 methodHandle method(THREAD, (methodOop)methods->obj_at(i));
1409 methodHandle new_method;
1410 rewrite_cp_refs_in_method(method, &new_method, CHECK_false);
1411 if (!new_method.is_null()) {
1412 // the method has been replaced so save the new method version
1413 methods->obj_at_put(i, new_method());
1414 }
1415 }
1416
1417 return true;
1418 }
1419
1420
1421 // Rewrite constant pool references in the specific method. This code
1422 // was adapted from Rewriter::rewrite_method().
1423 void VM_RedefineClasses::rewrite_cp_refs_in_method(methodHandle method,
1424 methodHandle *new_method_p, TRAPS) {
1425
1426 *new_method_p = methodHandle(); // default is no new method
1427
1428 // We cache a pointer to the bytecodes here in code_base. If GC
1429 // moves the methodOop, then the bytecodes will also move which
1430 // will likely cause a crash. We create a No_Safepoint_Verifier
1431 // object to detect whether we pass a possible safepoint in this
1432 // code block.
1433 No_Safepoint_Verifier nsv;
1434
1435 // Bytecodes and their length
1436 address code_base = method->code_base();
1437 int code_length = method->code_size();
1438
1439 int bc_length;
1440 for (int bci = 0; bci < code_length; bci += bc_length) {
1441 address bcp = code_base + bci;
1442 Bytecodes::Code c = (Bytecodes::Code)(*bcp);
1443
1444 bc_length = Bytecodes::length_for(c);
1445 if (bc_length == 0) {
1446 // More complicated bytecodes report a length of zero so
1447 // we have to try again a slightly different way.
1448 bc_length = Bytecodes::length_at(bcp);
1449 }
1450
1451 assert(bc_length != 0, "impossible bytecode length");
1452
1453 switch (c) {
1454 case Bytecodes::_ldc:
1455 {
1456 int cp_index = *(bcp + 1);
1457 int new_index = find_new_index(cp_index);
1458
1459 if (StressLdcRewrite && new_index == 0) {
1460 // If we are stressing ldc -> ldc_w rewriting, then we
1461 // always need a new_index value.
1462 new_index = cp_index;
1463 }
1464 if (new_index != 0) {
1465 // the original index is mapped so we have more work to do
1466 if (!StressLdcRewrite && new_index <= max_jubyte) {
1467 // The new value can still use ldc instead of ldc_w
1468 // unless we are trying to stress ldc -> ldc_w rewriting
1469 RC_TRACE_WITH_THREAD(0x00080000, THREAD,
1470 ("%s@" INTPTR_FORMAT " old=%d, new=%d", Bytecodes::name(c),
1471 bcp, cp_index, new_index));
1472 *(bcp + 1) = new_index;
1473 } else {
1474 RC_TRACE_WITH_THREAD(0x00080000, THREAD,
1475 ("%s->ldc_w@" INTPTR_FORMAT " old=%d, new=%d",
1476 Bytecodes::name(c), bcp, cp_index, new_index));
1477 // the new value needs ldc_w instead of ldc
1478 u_char inst_buffer[4]; // max instruction size is 4 bytes
1479 bcp = (address)inst_buffer;
1480 // construct new instruction sequence
1481 *bcp = Bytecodes::_ldc_w;
1482 bcp++;
1483 // Rewriter::rewrite_method() does not rewrite ldc -> ldc_w.
1484 // See comment below for difference between put_Java_u2()
1485 // and put_native_u2().
1486 Bytes::put_Java_u2(bcp, new_index);
1487
1488 Relocator rc(method, NULL /* no RelocatorListener needed */);
1489 methodHandle m;
1490 {
1491 Pause_No_Safepoint_Verifier pnsv(&nsv);
1492
1493 // ldc is 2 bytes and ldc_w is 3 bytes
1494 m = rc.insert_space_at(bci, 3, inst_buffer, THREAD);
1495 if (m.is_null() || HAS_PENDING_EXCEPTION) {
1496 guarantee(false, "insert_space_at() failed");
1497 }
1498 }
1499
1500 // return the new method so that the caller can update
1501 // the containing class
1502 *new_method_p = method = m;
1503 // switch our bytecode processing loop from the old method
1504 // to the new method
1505 code_base = method->code_base();
1506 code_length = method->code_size();
1507 bcp = code_base + bci;
1508 c = (Bytecodes::Code)(*bcp);
1509 bc_length = Bytecodes::length_for(c);
1510 assert(bc_length != 0, "sanity check");
1511 } // end we need ldc_w instead of ldc
1512 } // end if there is a mapped index
1513 } break;
1514
1515 // these bytecodes have a two-byte constant pool index
1516 case Bytecodes::_anewarray : // fall through
1517 case Bytecodes::_checkcast : // fall through
1518 case Bytecodes::_getfield : // fall through
1519 case Bytecodes::_getstatic : // fall through
1520 case Bytecodes::_instanceof : // fall through
1521 case Bytecodes::_invokeinterface: // fall through
1522 case Bytecodes::_invokespecial : // fall through
1523 case Bytecodes::_invokestatic : // fall through
1524 case Bytecodes::_invokevirtual : // fall through
1525 case Bytecodes::_ldc_w : // fall through
1526 case Bytecodes::_ldc2_w : // fall through
1527 case Bytecodes::_multianewarray : // fall through
1528 case Bytecodes::_new : // fall through
1529 case Bytecodes::_putfield : // fall through
1530 case Bytecodes::_putstatic :
1531 {
1532 address p = bcp + 1;
1533 int cp_index = Bytes::get_Java_u2(p);
1534 int new_index = find_new_index(cp_index);
1535 if (new_index != 0) {
1536 // the original index is mapped so update w/ new value
1537 RC_TRACE_WITH_THREAD(0x00080000, THREAD,
1538 ("%s@" INTPTR_FORMAT " old=%d, new=%d", Bytecodes::name(c),
1539 bcp, cp_index, new_index));
1540 // Rewriter::rewrite_method() uses put_native_u2() in this
1541 // situation because it is reusing the constant pool index
1542 // location for a native index into the constantPoolCache.
1543 // Since we are updating the constant pool index prior to
1544 // verification and constantPoolCache initialization, we
1545 // need to keep the new index in Java byte order.
1546 Bytes::put_Java_u2(p, new_index);
1547 }
1548 } break;
1549 }
1550 } // end for each bytecode
1551 } // end rewrite_cp_refs_in_method()
1552
1553
1554 // Rewrite constant pool references in the class_annotations field.
1555 bool VM_RedefineClasses::rewrite_cp_refs_in_class_annotations(
1556 instanceKlassHandle scratch_class, TRAPS) {
1557
1558 typeArrayHandle class_annotations(THREAD,
1559 scratch_class->class_annotations());
1560 if (class_annotations.is_null() || class_annotations->length() == 0) {
1561 // no class_annotations so nothing to do
1562 return true;
1563 }
1564
1565 RC_TRACE_WITH_THREAD(0x02000000, THREAD,
1566 ("class_annotations length=%d", class_annotations->length()));
1567
1568 int byte_i = 0; // byte index into class_annotations
1569 return rewrite_cp_refs_in_annotations_typeArray(class_annotations, byte_i,
1570 THREAD);
1571 }
1572
1573
1574 // Rewrite constant pool references in an annotations typeArray. This
1575 // "structure" is adapted from the RuntimeVisibleAnnotations_attribute
1576 // that is described in section 4.8.15 of the 2nd-edition of the VM spec:
1577 //
1578 // annotations_typeArray {
1579 // u2 num_annotations;
1580 // annotation annotations[num_annotations];
1581 // }
1582 //
1583 bool VM_RedefineClasses::rewrite_cp_refs_in_annotations_typeArray(
1584 typeArrayHandle annotations_typeArray, int &byte_i_ref, TRAPS) {
1585
1586 if ((byte_i_ref + 2) > annotations_typeArray->length()) {
1587 // not enough room for num_annotations field
1588 RC_TRACE_WITH_THREAD(0x02000000, THREAD,
1589 ("length() is too small for num_annotations field"));
1590 return false;
1591 }
1592
1593 u2 num_annotations = Bytes::get_Java_u2((address)
1594 annotations_typeArray->byte_at_addr(byte_i_ref));
1595 byte_i_ref += 2;
1596
1597 RC_TRACE_WITH_THREAD(0x02000000, THREAD,
1598 ("num_annotations=%d", num_annotations));
1599
1600 int calc_num_annotations = 0;
1601 for (; calc_num_annotations < num_annotations; calc_num_annotations++) {
1602 if (!rewrite_cp_refs_in_annotation_struct(annotations_typeArray,
1603 byte_i_ref, THREAD)) {
1604 RC_TRACE_WITH_THREAD(0x02000000, THREAD,
1605 ("bad annotation_struct at %d", calc_num_annotations));
1606 // propagate failure back to caller
1607 return false;
1608 }
1609 }
1610 assert(num_annotations == calc_num_annotations, "sanity check");
1611
1612 return true;
1613 } // end rewrite_cp_refs_in_annotations_typeArray()
1614
1615
1616 // Rewrite constant pool references in the annotation struct portion of
1617 // an annotations_typeArray. This "structure" is from section 4.8.15 of
1618 // the 2nd-edition of the VM spec:
1619 //
1620 // struct annotation {
1621 // u2 type_index;
1622 // u2 num_element_value_pairs;
1623 // {
1624 // u2 element_name_index;
1625 // element_value value;
1626 // } element_value_pairs[num_element_value_pairs];
1627 // }
1628 //
1629 bool VM_RedefineClasses::rewrite_cp_refs_in_annotation_struct(
1630 typeArrayHandle annotations_typeArray, int &byte_i_ref, TRAPS) {
1631 if ((byte_i_ref + 2 + 2) > annotations_typeArray->length()) {
1632 // not enough room for smallest annotation_struct
1633 RC_TRACE_WITH_THREAD(0x02000000, THREAD,
1634 ("length() is too small for annotation_struct"));
1635 return false;
1636 }
1637
1638 u2 type_index = rewrite_cp_ref_in_annotation_data(annotations_typeArray,
1639 byte_i_ref, "mapped old type_index=%d", THREAD);
1640
1641 u2 num_element_value_pairs = Bytes::get_Java_u2((address)
1642 annotations_typeArray->byte_at_addr(
1643 byte_i_ref));
1644 byte_i_ref += 2;
1645
1646 RC_TRACE_WITH_THREAD(0x02000000, THREAD,
1647 ("type_index=%d num_element_value_pairs=%d", type_index,
1648 num_element_value_pairs));
1649
1650 int calc_num_element_value_pairs = 0;
1651 for (; calc_num_element_value_pairs < num_element_value_pairs;
1652 calc_num_element_value_pairs++) {
1653 if ((byte_i_ref + 2) > annotations_typeArray->length()) {
1654 // not enough room for another element_name_index, let alone
1655 // the rest of another component
1656 RC_TRACE_WITH_THREAD(0x02000000, THREAD,
1657 ("length() is too small for element_name_index"));
1658 return false;
1659 }
1660
1661 u2 element_name_index = rewrite_cp_ref_in_annotation_data(
1662 annotations_typeArray, byte_i_ref,
1663 "mapped old element_name_index=%d", THREAD);
1664
1665 RC_TRACE_WITH_THREAD(0x02000000, THREAD,
1666 ("element_name_index=%d", element_name_index));
1667
1668 if (!rewrite_cp_refs_in_element_value(annotations_typeArray,
1669 byte_i_ref, THREAD)) {
1670 RC_TRACE_WITH_THREAD(0x02000000, THREAD,
1671 ("bad element_value at %d", calc_num_element_value_pairs));
1672 // propagate failure back to caller
1673 return false;
1674 }
1675 } // end for each component
1676 assert(num_element_value_pairs == calc_num_element_value_pairs,
1677 "sanity check");
1678
1679 return true;
1680 } // end rewrite_cp_refs_in_annotation_struct()
1681
1682
1683 // Rewrite a constant pool reference at the current position in
1684 // annotations_typeArray if needed. Returns the original constant
1685 // pool reference if a rewrite was not needed or the new constant
1686 // pool reference if a rewrite was needed.
1687 u2 VM_RedefineClasses::rewrite_cp_ref_in_annotation_data(
1688 typeArrayHandle annotations_typeArray, int &byte_i_ref,
1689 const char * trace_mesg, TRAPS) {
1690
1691 address cp_index_addr = (address)
1692 annotations_typeArray->byte_at_addr(byte_i_ref);
1693 u2 old_cp_index = Bytes::get_Java_u2(cp_index_addr);
1694 u2 new_cp_index = find_new_index(old_cp_index);
1695 if (new_cp_index != 0) {
1696 RC_TRACE_WITH_THREAD(0x02000000, THREAD, (trace_mesg, old_cp_index));
1697 Bytes::put_Java_u2(cp_index_addr, new_cp_index);
1698 old_cp_index = new_cp_index;
1699 }
1700 byte_i_ref += 2;
1701 return old_cp_index;
1702 }
1703
1704
1705 // Rewrite constant pool references in the element_value portion of an
1706 // annotations_typeArray. This "structure" is from section 4.8.15.1 of
1707 // the 2nd-edition of the VM spec:
1708 //
1709 // struct element_value {
1710 // u1 tag;
1711 // union {
1712 // u2 const_value_index;
1713 // {
1714 // u2 type_name_index;
1715 // u2 const_name_index;
1716 // } enum_const_value;
1717 // u2 class_info_index;
1718 // annotation annotation_value;
1719 // struct {
1720 // u2 num_values;
1721 // element_value values[num_values];
1722 // } array_value;
1723 // } value;
1724 // }
1725 //
1726 bool VM_RedefineClasses::rewrite_cp_refs_in_element_value(
1727 typeArrayHandle annotations_typeArray, int &byte_i_ref, TRAPS) {
1728
1729 if ((byte_i_ref + 1) > annotations_typeArray->length()) {
1730 // not enough room for a tag let alone the rest of an element_value
1731 RC_TRACE_WITH_THREAD(0x02000000, THREAD,
1732 ("length() is too small for a tag"));
1733 return false;
1734 }
1735
1736 u1 tag = annotations_typeArray->byte_at(byte_i_ref);
1737 byte_i_ref++;
1738 RC_TRACE_WITH_THREAD(0x02000000, THREAD, ("tag='%c'", tag));
1739
1740 switch (tag) {
1741 // These BaseType tag values are from Table 4.2 in VM spec:
1742 case 'B': // byte
1743 case 'C': // char
1744 case 'D': // double
1745 case 'F': // float
1746 case 'I': // int
1747 case 'J': // long
1748 case 'S': // short
1749 case 'Z': // boolean
1750
1751 // The remaining tag values are from Table 4.8 in the 2nd-edition of
1752 // the VM spec:
1753 case 's':
1754 {
1755 // For the above tag values (including the BaseType values),
1756 // value.const_value_index is right union field.
1757
1758 if ((byte_i_ref + 2) > annotations_typeArray->length()) {
1759 // not enough room for a const_value_index
1760 RC_TRACE_WITH_THREAD(0x02000000, THREAD,
1761 ("length() is too small for a const_value_index"));
1762 return false;
1763 }
1764
1765 u2 const_value_index = rewrite_cp_ref_in_annotation_data(
1766 annotations_typeArray, byte_i_ref,
1767 "mapped old const_value_index=%d", THREAD);
1768
1769 RC_TRACE_WITH_THREAD(0x02000000, THREAD,
1770 ("const_value_index=%d", const_value_index));
1771 } break;
1772
1773 case 'e':
1774 {
1775 // for the above tag value, value.enum_const_value is right union field
1776
1777 if ((byte_i_ref + 4) > annotations_typeArray->length()) {
1778 // not enough room for a enum_const_value
1779 RC_TRACE_WITH_THREAD(0x02000000, THREAD,
1780 ("length() is too small for a enum_const_value"));
1781 return false;
1782 }
1783
1784 u2 type_name_index = rewrite_cp_ref_in_annotation_data(
1785 annotations_typeArray, byte_i_ref,
1786 "mapped old type_name_index=%d", THREAD);
1787
1788 u2 const_name_index = rewrite_cp_ref_in_annotation_data(
1789 annotations_typeArray, byte_i_ref,
1790 "mapped old const_name_index=%d", THREAD);
1791
1792 RC_TRACE_WITH_THREAD(0x02000000, THREAD,
1793 ("type_name_index=%d const_name_index=%d", type_name_index,
1794 const_name_index));
1795 } break;
1796
1797 case 'c':
1798 {
1799 // for the above tag value, value.class_info_index is right union field
1800
1801 if ((byte_i_ref + 2) > annotations_typeArray->length()) {
1802 // not enough room for a class_info_index
1803 RC_TRACE_WITH_THREAD(0x02000000, THREAD,
1804 ("length() is too small for a class_info_index"));
1805 return false;
1806 }
1807
1808 u2 class_info_index = rewrite_cp_ref_in_annotation_data(
1809 annotations_typeArray, byte_i_ref,
1810 "mapped old class_info_index=%d", THREAD);
1811
1812 RC_TRACE_WITH_THREAD(0x02000000, THREAD,
1813 ("class_info_index=%d", class_info_index));
1814 } break;
1815
1816 case '@':
1817 // For the above tag value, value.attr_value is the right union
1818 // field. This is a nested annotation.
1819 if (!rewrite_cp_refs_in_annotation_struct(annotations_typeArray,
1820 byte_i_ref, THREAD)) {
1821 // propagate failure back to caller
1822 return false;
1823 }
1824 break;
1825
1826 case '[':
1827 {
1828 if ((byte_i_ref + 2) > annotations_typeArray->length()) {
1829 // not enough room for a num_values field
1830 RC_TRACE_WITH_THREAD(0x02000000, THREAD,
1831 ("length() is too small for a num_values field"));
1832 return false;
1833 }
1834
1835 // For the above tag value, value.array_value is the right union
1836 // field. This is an array of nested element_value.
1837 u2 num_values = Bytes::get_Java_u2((address)
1838 annotations_typeArray->byte_at_addr(byte_i_ref));
1839 byte_i_ref += 2;
1840 RC_TRACE_WITH_THREAD(0x02000000, THREAD, ("num_values=%d", num_values));
1841
1842 int calc_num_values = 0;
1843 for (; calc_num_values < num_values; calc_num_values++) {
1844 if (!rewrite_cp_refs_in_element_value(
1845 annotations_typeArray, byte_i_ref, THREAD)) {
1846 RC_TRACE_WITH_THREAD(0x02000000, THREAD,
1847 ("bad nested element_value at %d", calc_num_values));
1848 // propagate failure back to caller
1849 return false;
1850 }
1851 }
1852 assert(num_values == calc_num_values, "sanity check");
1853 } break;
1854
1855 default:
1856 RC_TRACE_WITH_THREAD(0x02000000, THREAD, ("bad tag=0x%x", tag));
1857 return false;
1858 } // end decode tag field
1859
1860 return true;
1861 } // end rewrite_cp_refs_in_element_value()
1862
1863
1864 // Rewrite constant pool references in a fields_annotations field.
1865 bool VM_RedefineClasses::rewrite_cp_refs_in_fields_annotations(
1866 instanceKlassHandle scratch_class, TRAPS) {
1867
1868 objArrayHandle fields_annotations(THREAD,
1869 scratch_class->fields_annotations());
1870
1871 if (fields_annotations.is_null() || fields_annotations->length() == 0) {
1872 // no fields_annotations so nothing to do
1873 return true;
1874 }
1875
1876 RC_TRACE_WITH_THREAD(0x02000000, THREAD,
1877 ("fields_annotations length=%d", fields_annotations->length()));
1878
1879 for (int i = 0; i < fields_annotations->length(); i++) {
1880 typeArrayHandle field_annotations(THREAD,
1881 (typeArrayOop)fields_annotations->obj_at(i));
1882 if (field_annotations.is_null() || field_annotations->length() == 0) {
1883 // this field does not have any annotations so skip it
1884 continue;
1885 }
1886
1887 int byte_i = 0; // byte index into field_annotations
1888 if (!rewrite_cp_refs_in_annotations_typeArray(field_annotations, byte_i,
1889 THREAD)) {
1890 RC_TRACE_WITH_THREAD(0x02000000, THREAD,
1891 ("bad field_annotations at %d", i));
1892 // propagate failure back to caller
1893 return false;
1894 }
1895 }
1896
1897 return true;
1898 } // end rewrite_cp_refs_in_fields_annotations()
1899
1900
1901 // Rewrite constant pool references in a methods_annotations field.
1902 bool VM_RedefineClasses::rewrite_cp_refs_in_methods_annotations(
1903 instanceKlassHandle scratch_class, TRAPS) {
1904
1905 objArrayHandle methods_annotations(THREAD,
1906 scratch_class->methods_annotations());
1907
1908 if (methods_annotations.is_null() || methods_annotations->length() == 0) {
1909 // no methods_annotations so nothing to do
1910 return true;
1911 }
1912
1913 RC_TRACE_WITH_THREAD(0x02000000, THREAD,
1914 ("methods_annotations length=%d", methods_annotations->length()));
1915
1916 for (int i = 0; i < methods_annotations->length(); i++) {
1917 typeArrayHandle method_annotations(THREAD,
1918 (typeArrayOop)methods_annotations->obj_at(i));
1919 if (method_annotations.is_null() || method_annotations->length() == 0) {
1920 // this method does not have any annotations so skip it
1921 continue;
1922 }
1923
1924 int byte_i = 0; // byte index into method_annotations
1925 if (!rewrite_cp_refs_in_annotations_typeArray(method_annotations, byte_i,
1926 THREAD)) {
1927 RC_TRACE_WITH_THREAD(0x02000000, THREAD,
1928 ("bad method_annotations at %d", i));
1929 // propagate failure back to caller
1930 return false;
1931 }
1932 }
1933
1934 return true;
1935 } // end rewrite_cp_refs_in_methods_annotations()
1936
1937
1938 // Rewrite constant pool references in a methods_parameter_annotations
1939 // field. This "structure" is adapted from the
1940 // RuntimeVisibleParameterAnnotations_attribute described in section
1941 // 4.8.17 of the 2nd-edition of the VM spec:
1942 //
1943 // methods_parameter_annotations_typeArray {
1944 // u1 num_parameters;
1945 // {
1946 // u2 num_annotations;
1947 // annotation annotations[num_annotations];
1948 // } parameter_annotations[num_parameters];
1949 // }
1950 //
1951 bool VM_RedefineClasses::rewrite_cp_refs_in_methods_parameter_annotations(
1952 instanceKlassHandle scratch_class, TRAPS) {
1953
1954 objArrayHandle methods_parameter_annotations(THREAD,
1955 scratch_class->methods_parameter_annotations());
1956
1957 if (methods_parameter_annotations.is_null()
1958 || methods_parameter_annotations->length() == 0) {
1959 // no methods_parameter_annotations so nothing to do
1960 return true;
1961 }
1962
1963 RC_TRACE_WITH_THREAD(0x02000000, THREAD,
1964 ("methods_parameter_annotations length=%d",
1965 methods_parameter_annotations->length()));
1966
1967 for (int i = 0; i < methods_parameter_annotations->length(); i++) {
1968 typeArrayHandle method_parameter_annotations(THREAD,
1969 (typeArrayOop)methods_parameter_annotations->obj_at(i));
1970 if (method_parameter_annotations.is_null()
1971 || method_parameter_annotations->length() == 0) {
1972 // this method does not have any parameter annotations so skip it
1973 continue;
1974 }
1975
1976 if (method_parameter_annotations->length() < 1) {
1977 // not enough room for a num_parameters field
1978 RC_TRACE_WITH_THREAD(0x02000000, THREAD,
1979 ("length() is too small for a num_parameters field at %d", i));
1980 return false;
1981 }
1982
1983 int byte_i = 0; // byte index into method_parameter_annotations
1984
1985 u1 num_parameters = method_parameter_annotations->byte_at(byte_i);
1986 byte_i++;
1987
1988 RC_TRACE_WITH_THREAD(0x02000000, THREAD,
1989 ("num_parameters=%d", num_parameters));
1990
1991 int calc_num_parameters = 0;
1992 for (; calc_num_parameters < num_parameters; calc_num_parameters++) {
1993 if (!rewrite_cp_refs_in_annotations_typeArray(
1994 method_parameter_annotations, byte_i, THREAD)) {
1995 RC_TRACE_WITH_THREAD(0x02000000, THREAD,
1996 ("bad method_parameter_annotations at %d", calc_num_parameters));
1997 // propagate failure back to caller
1998 return false;
1999 }
2000 }
2001 assert(num_parameters == calc_num_parameters, "sanity check");
2002 }
2003
2004 return true;
2005 } // end rewrite_cp_refs_in_methods_parameter_annotations()
2006
2007
2008 // Rewrite constant pool references in a methods_default_annotations
2009 // field. This "structure" is adapted from the AnnotationDefault_attribute
2010 // that is described in section 4.8.19 of the 2nd-edition of the VM spec:
2011 //
2012 // methods_default_annotations_typeArray {
2013 // element_value default_value;
2014 // }
2015 //
2016 bool VM_RedefineClasses::rewrite_cp_refs_in_methods_default_annotations(
2017 instanceKlassHandle scratch_class, TRAPS) {
2018
2019 objArrayHandle methods_default_annotations(THREAD,
2020 scratch_class->methods_default_annotations());
2021
2022 if (methods_default_annotations.is_null()
2023 || methods_default_annotations->length() == 0) {
2024 // no methods_default_annotations so nothing to do
2025 return true;
2026 }
2027
2028 RC_TRACE_WITH_THREAD(0x02000000, THREAD,
2029 ("methods_default_annotations length=%d",
2030 methods_default_annotations->length()));
2031
2032 for (int i = 0; i < methods_default_annotations->length(); i++) {
2033 typeArrayHandle method_default_annotations(THREAD,
2034 (typeArrayOop)methods_default_annotations->obj_at(i));
2035 if (method_default_annotations.is_null()
2036 || method_default_annotations->length() == 0) {
2037 // this method does not have any default annotations so skip it
2038 continue;
2039 }
2040
2041 int byte_i = 0; // byte index into method_default_annotations
2042
2043 if (!rewrite_cp_refs_in_element_value(
2044 method_default_annotations, byte_i, THREAD)) {
2045 RC_TRACE_WITH_THREAD(0x02000000, THREAD,
2046 ("bad default element_value at %d", i));
2047 // propagate failure back to caller
2048 return false;
2049 }
2050 }
2051
2052 return true;
2053 } // end rewrite_cp_refs_in_methods_default_annotations()
2054
2055
2056 // Rewrite constant pool references in the method's stackmap table.
2057 // These "structures" are adapted from the StackMapTable_attribute that
2058 // is described in section 4.8.4 of the 6.0 version of the VM spec
2059 // (dated 2005.10.26):
2060 // file:///net/quincunx.sfbay/export/gbracha/ClassFile-Java6.pdf
2061 //
2062 // stack_map {
2063 // u2 number_of_entries;
2064 // stack_map_frame entries[number_of_entries];
2065 // }
2066 //
2067 void VM_RedefineClasses::rewrite_cp_refs_in_stack_map_table(
2068 methodHandle method, TRAPS) {
2069
2070 if (!method->has_stackmap_table()) {
2071 return;
2072 }
2073
2074 typeArrayOop stackmap_data = method->stackmap_data();
2075 address stackmap_p = (address)stackmap_data->byte_at_addr(0);
2076 address stackmap_end = stackmap_p + stackmap_data->length();
2077
2078 assert(stackmap_p + 2 <= stackmap_end, "no room for number_of_entries");
2079 u2 number_of_entries = Bytes::get_Java_u2(stackmap_p);
2080 stackmap_p += 2;
2081
2082 RC_TRACE_WITH_THREAD(0x04000000, THREAD,
2083 ("number_of_entries=%u", number_of_entries));
2084
2085 // walk through each stack_map_frame
2086 u2 calc_number_of_entries = 0;
2087 for (; calc_number_of_entries < number_of_entries; calc_number_of_entries++) {
2088 // The stack_map_frame structure is a u1 frame_type followed by
2089 // 0 or more bytes of data:
2090 //
2091 // union stack_map_frame {
2092 // same_frame;
2093 // same_locals_1_stack_item_frame;
2094 // same_locals_1_stack_item_frame_extended;
2095 // chop_frame;
2096 // same_frame_extended;
2097 // append_frame;
2098 // full_frame;
2099 // }
2100
2101 assert(stackmap_p + 1 <= stackmap_end, "no room for frame_type");
2102 // The Linux compiler does not like frame_type to be u1 or u2. It
2103 // issues the following warning for the first if-statement below:
2104 //
2105 // "warning: comparison is always true due to limited range of data type"
2106 //
2107 u4 frame_type = *stackmap_p;
2108 stackmap_p++;
2109
2110 // same_frame {
2111 // u1 frame_type = SAME; /* 0-63 */
2112 // }
2113 if (frame_type >= 0 && frame_type <= 63) {
2114 // nothing more to do for same_frame
2115 }
2116
2117 // same_locals_1_stack_item_frame {
2118 // u1 frame_type = SAME_LOCALS_1_STACK_ITEM; /* 64-127 */
2119 // verification_type_info stack[1];
2120 // }
2121 else if (frame_type >= 64 && frame_type <= 127) {
2122 rewrite_cp_refs_in_verification_type_info(stackmap_p, stackmap_end,
2123 calc_number_of_entries, frame_type, THREAD);
2124 }
2125
2126 // reserved for future use
2127 else if (frame_type >= 128 && frame_type <= 246) {
2128 // nothing more to do for reserved frame_types
2129 }
2130
2131 // same_locals_1_stack_item_frame_extended {
2132 // u1 frame_type = SAME_LOCALS_1_STACK_ITEM_EXTENDED; /* 247 */
2133 // u2 offset_delta;
2134 // verification_type_info stack[1];
2135 // }
2136 else if (frame_type == 247) {
2137 stackmap_p += 2;
2138 rewrite_cp_refs_in_verification_type_info(stackmap_p, stackmap_end,
2139 calc_number_of_entries, frame_type, THREAD);
2140 }
2141
2142 // chop_frame {
2143 // u1 frame_type = CHOP; /* 248-250 */
2144 // u2 offset_delta;
2145 // }
2146 else if (frame_type >= 248 && frame_type <= 250) {
2147 stackmap_p += 2;
2148 }
2149
2150 // same_frame_extended {
2151 // u1 frame_type = SAME_FRAME_EXTENDED; /* 251*/
2152 // u2 offset_delta;
2153 // }
2154 else if (frame_type == 251) {
2155 stackmap_p += 2;
2156 }
2157
2158 // append_frame {
2159 // u1 frame_type = APPEND; /* 252-254 */
2160 // u2 offset_delta;
2161 // verification_type_info locals[frame_type - 251];
2162 // }
2163 else if (frame_type >= 252 && frame_type <= 254) {
2164 assert(stackmap_p + 2 <= stackmap_end,
2165 "no room for offset_delta");
2166 stackmap_p += 2;
2167 u1 len = frame_type - 251;
2168 for (u1 i = 0; i < len; i++) {
2169 rewrite_cp_refs_in_verification_type_info(stackmap_p, stackmap_end,
2170 calc_number_of_entries, frame_type, THREAD);
2171 }
2172 }
2173
2174 // full_frame {
2175 // u1 frame_type = FULL_FRAME; /* 255 */
2176 // u2 offset_delta;
2177 // u2 number_of_locals;
2178 // verification_type_info locals[number_of_locals];
2179 // u2 number_of_stack_items;
2180 // verification_type_info stack[number_of_stack_items];
2181 // }
2182 else if (frame_type == 255) {
2183 assert(stackmap_p + 2 + 2 <= stackmap_end,
2184 "no room for smallest full_frame");
2185 stackmap_p += 2;
2186
2187 u2 number_of_locals = Bytes::get_Java_u2(stackmap_p);
2188 stackmap_p += 2;
2189
2190 for (u2 locals_i = 0; locals_i < number_of_locals; locals_i++) {
2191 rewrite_cp_refs_in_verification_type_info(stackmap_p, stackmap_end,
2192 calc_number_of_entries, frame_type, THREAD);
2193 }
2194
2195 // Use the largest size for the number_of_stack_items, but only get
2196 // the right number of bytes.
2197 u2 number_of_stack_items = Bytes::get_Java_u2(stackmap_p);
2198 stackmap_p += 2;
2199
2200 for (u2 stack_i = 0; stack_i < number_of_stack_items; stack_i++) {
2201 rewrite_cp_refs_in_verification_type_info(stackmap_p, stackmap_end,
2202 calc_number_of_entries, frame_type, THREAD);
2203 }
2204 }
2205 } // end while there is a stack_map_frame
2206 assert(number_of_entries == calc_number_of_entries, "sanity check");
2207 } // end rewrite_cp_refs_in_stack_map_table()
2208
2209
2210 // Rewrite constant pool references in the verification type info
2211 // portion of the method's stackmap table. These "structures" are
2212 // adapted from the StackMapTable_attribute that is described in
2213 // section 4.8.4 of the 6.0 version of the VM spec (dated 2005.10.26):
2214 // file:///net/quincunx.sfbay/export/gbracha/ClassFile-Java6.pdf
2215 //
2216 // The verification_type_info structure is a u1 tag followed by 0 or
2217 // more bytes of data:
2218 //
2219 // union verification_type_info {
2220 // Top_variable_info;
2221 // Integer_variable_info;
2222 // Float_variable_info;
2223 // Long_variable_info;
2224 // Double_variable_info;
2225 // Null_variable_info;
2226 // UninitializedThis_variable_info;
2227 // Object_variable_info;
2228 // Uninitialized_variable_info;
2229 // }
2230 //
2231 void VM_RedefineClasses::rewrite_cp_refs_in_verification_type_info(
2232 address& stackmap_p_ref, address stackmap_end, u2 frame_i,
2233 u1 frame_type, TRAPS) {
2234
2235 assert(stackmap_p_ref + 1 <= stackmap_end, "no room for tag");
2236 u1 tag = *stackmap_p_ref;
2237 stackmap_p_ref++;
2238
2239 switch (tag) {
2240 // Top_variable_info {
2241 // u1 tag = ITEM_Top; /* 0 */
2242 // }
2243 // verificationType.hpp has zero as ITEM_Bogus instead of ITEM_Top
2244 case 0: // fall through
2245
2246 // Integer_variable_info {
2247 // u1 tag = ITEM_Integer; /* 1 */
2248 // }
2249 case ITEM_Integer: // fall through
2250
2251 // Float_variable_info {
2252 // u1 tag = ITEM_Float; /* 2 */
2253 // }
2254 case ITEM_Float: // fall through
2255
2256 // Double_variable_info {
2257 // u1 tag = ITEM_Double; /* 3 */
2258 // }
2259 case ITEM_Double: // fall through
2260
2261 // Long_variable_info {
2262 // u1 tag = ITEM_Long; /* 4 */
2263 // }
2264 case ITEM_Long: // fall through
2265
2266 // Null_variable_info {
2267 // u1 tag = ITEM_Null; /* 5 */
2268 // }
2269 case ITEM_Null: // fall through
2270
2271 // UninitializedThis_variable_info {
2272 // u1 tag = ITEM_UninitializedThis; /* 6 */
2273 // }
2274 case ITEM_UninitializedThis:
2275 // nothing more to do for the above tag types
2276 break;
2277
2278 // Object_variable_info {
2279 // u1 tag = ITEM_Object; /* 7 */
2280 // u2 cpool_index;
2281 // }
2282 case ITEM_Object:
2283 {
2284 assert(stackmap_p_ref + 2 <= stackmap_end, "no room for cpool_index");
2285 u2 cpool_index = Bytes::get_Java_u2(stackmap_p_ref);
2286 u2 new_cp_index = find_new_index(cpool_index);
2287 if (new_cp_index != 0) {
2288 RC_TRACE_WITH_THREAD(0x04000000, THREAD,
2289 ("mapped old cpool_index=%d", cpool_index));
2290 Bytes::put_Java_u2(stackmap_p_ref, new_cp_index);
2291 cpool_index = new_cp_index;
2292 }
2293 stackmap_p_ref += 2;
2294
2295 RC_TRACE_WITH_THREAD(0x04000000, THREAD,
2296 ("frame_i=%u, frame_type=%u, cpool_index=%d", frame_i,
2297 frame_type, cpool_index));
2298 } break;
2299
2300 // Uninitialized_variable_info {
2301 // u1 tag = ITEM_Uninitialized; /* 8 */
2302 // u2 offset;
2303 // }
2304 case ITEM_Uninitialized:
2305 assert(stackmap_p_ref + 2 <= stackmap_end, "no room for offset");
2306 stackmap_p_ref += 2;
2307 break;
2308
2309 default:
2310 RC_TRACE_WITH_THREAD(0x04000000, THREAD,
2311 ("frame_i=%u, frame_type=%u, bad tag=0x%x", frame_i, frame_type, tag));
2312 ShouldNotReachHere();
2313 break;
2314 } // end switch (tag)
2315 } // end rewrite_cp_refs_in_verification_type_info()
2316
2317
2318 // Change the constant pool associated with klass scratch_class to
2319 // scratch_cp. If shrink is true, then scratch_cp_length elements
2320 // are copied from scratch_cp to a smaller constant pool and the
2321 // smaller constant pool is associated with scratch_class.
2322 void VM_RedefineClasses::set_new_constant_pool(
2323 instanceKlassHandle scratch_class, constantPoolHandle scratch_cp,
2324 int scratch_cp_length, bool shrink, TRAPS) {
2325 assert(!shrink || scratch_cp->length() >= scratch_cp_length, "sanity check");
2326
2327 if (shrink) {
2328 // scratch_cp is a merged constant pool and has enough space for a
2329 // worst case merge situation. We want to associate the minimum
2330 // sized constant pool with the klass to save space.
2331 constantPoolHandle smaller_cp(THREAD,
2332 oopFactory::new_constantPool(scratch_cp_length,
2333 methodOopDesc::IsUnsafeConc,
2334 THREAD));
2335 // preserve orig_length() value in the smaller copy
2336 int orig_length = scratch_cp->orig_length();
2337 assert(orig_length != 0, "sanity check");
2338 smaller_cp->set_orig_length(orig_length);
2339 scratch_cp->copy_cp_to(1, scratch_cp_length - 1, smaller_cp, 1, THREAD);
2340 scratch_cp = smaller_cp;
2341 smaller_cp()->set_is_conc_safe(true);
2342 }
2343
2344 // attach new constant pool to klass
2345 scratch_cp->set_pool_holder(scratch_class());
2346
2347 // attach klass to new constant pool
2348 scratch_class->set_constants(scratch_cp());
2349
2350 int i; // for portability
2351
2352 // update each field in klass to use new constant pool indices as needed
2353 typeArrayHandle fields(THREAD, scratch_class->fields());
2354 int n_fields = fields->length();
2355 for (i = 0; i < n_fields; i += instanceKlass::next_offset) {
2356 jshort cur_index = fields->short_at(i + instanceKlass::name_index_offset);
2357 jshort new_index = find_new_index(cur_index);
2358 if (new_index != 0) {
2359 RC_TRACE_WITH_THREAD(0x00080000, THREAD,
2360 ("field-name_index change: %d to %d", cur_index, new_index));
2361 fields->short_at_put(i + instanceKlass::name_index_offset, new_index);
2362 }
2363 cur_index = fields->short_at(i + instanceKlass::signature_index_offset);
2364 new_index = find_new_index(cur_index);
2365 if (new_index != 0) {
2366 RC_TRACE_WITH_THREAD(0x00080000, THREAD,
2367 ("field-signature_index change: %d to %d", cur_index, new_index));
2368 fields->short_at_put(i + instanceKlass::signature_index_offset,
2369 new_index);
2370 }
2371 cur_index = fields->short_at(i + instanceKlass::initval_index_offset);
2372 new_index = find_new_index(cur_index);
2373 if (new_index != 0) {
2374 RC_TRACE_WITH_THREAD(0x00080000, THREAD,
2375 ("field-initval_index change: %d to %d", cur_index, new_index));
2376 fields->short_at_put(i + instanceKlass::initval_index_offset, new_index);
2377 }
2378 cur_index = fields->short_at(i + instanceKlass::generic_signature_offset);
2379 new_index = find_new_index(cur_index);
2380 if (new_index != 0) {
2381 RC_TRACE_WITH_THREAD(0x00080000, THREAD,
2382 ("field-generic_signature change: %d to %d", cur_index, new_index));
2383 fields->short_at_put(i + instanceKlass::generic_signature_offset,
2384 new_index);
2385 }
2386 } // end for each field
2387
2388 // Update constant pool indices in the inner classes info to use
2389 // new constant indices as needed. The inner classes info is a
2390 // quadruple:
2391 // (inner_class_info, outer_class_info, inner_name, inner_access_flags)
2392 typeArrayOop inner_class_list = scratch_class->inner_classes();
2393 int icl_length = (inner_class_list == NULL) ? 0 : inner_class_list->length();
2394 if (icl_length > 0) {
2395 typeArrayHandle inner_class_list_h(THREAD, inner_class_list);
2396 for (int i = 0; i < icl_length;
2397 i += instanceKlass::inner_class_next_offset) {
2398 int cur_index = inner_class_list_h->ushort_at(i
2399 + instanceKlass::inner_class_inner_class_info_offset);
2400 if (cur_index == 0) {
2401 continue; // JVM spec. allows null inner class refs so skip it
2402 }
2403 int new_index = find_new_index(cur_index);
2404 if (new_index != 0) {
2405 RC_TRACE_WITH_THREAD(0x00080000, THREAD,
2406 ("inner_class_info change: %d to %d", cur_index, new_index));
2407 inner_class_list_h->ushort_at_put(i
2408 + instanceKlass::inner_class_inner_class_info_offset, new_index);
2409 }
2410 cur_index = inner_class_list_h->ushort_at(i
2411 + instanceKlass::inner_class_outer_class_info_offset);
2412 new_index = find_new_index(cur_index);
2413 if (new_index != 0) {
2414 RC_TRACE_WITH_THREAD(0x00080000, THREAD,
2415 ("outer_class_info change: %d to %d", cur_index, new_index));
2416 inner_class_list_h->ushort_at_put(i
2417 + instanceKlass::inner_class_outer_class_info_offset, new_index);
2418 }
2419 cur_index = inner_class_list_h->ushort_at(i
2420 + instanceKlass::inner_class_inner_name_offset);
2421 new_index = find_new_index(cur_index);
2422 if (new_index != 0) {
2423 RC_TRACE_WITH_THREAD(0x00080000, THREAD,
2424 ("inner_name change: %d to %d", cur_index, new_index));
2425 inner_class_list_h->ushort_at_put(i
2426 + instanceKlass::inner_class_inner_name_offset, new_index);
2427 }
2428 } // end for each inner class
2429 } // end if we have inner classes
2430
2431 // Attach each method in klass to the new constant pool and update
2432 // to use new constant pool indices as needed:
2433 objArrayHandle methods(THREAD, scratch_class->methods());
2434 for (i = methods->length() - 1; i >= 0; i--) {
2435 methodHandle method(THREAD, (methodOop)methods->obj_at(i));
2436 method->set_constants(scratch_cp());
2437
2438 int new_index = find_new_index(method->name_index());
2439 if (new_index != 0) {
2440 RC_TRACE_WITH_THREAD(0x00080000, THREAD,
2441 ("method-name_index change: %d to %d", method->name_index(),
2442 new_index));
2443 method->set_name_index(new_index);
2444 }
2445 new_index = find_new_index(method->signature_index());
2446 if (new_index != 0) {
2447 RC_TRACE_WITH_THREAD(0x00080000, THREAD,
2448 ("method-signature_index change: %d to %d",
2449 method->signature_index(), new_index));
2450 method->set_signature_index(new_index);
2451 }
2452 new_index = find_new_index(method->generic_signature_index());
2453 if (new_index != 0) {
2454 RC_TRACE_WITH_THREAD(0x00080000, THREAD,
2455 ("method-generic_signature_index change: %d to %d",
2456 method->generic_signature_index(), new_index));
2457 method->set_generic_signature_index(new_index);
2458 }
2459
2460 // Update constant pool indices in the method's checked exception
2461 // table to use new constant indices as needed.
2462 int cext_length = method->checked_exceptions_length();
2463 if (cext_length > 0) {
2464 CheckedExceptionElement * cext_table =
2465 method->checked_exceptions_start();
2466 for (int j = 0; j < cext_length; j++) {
2467 int cur_index = cext_table[j].class_cp_index;
2468 int new_index = find_new_index(cur_index);
2469 if (new_index != 0) {
2470 RC_TRACE_WITH_THREAD(0x00080000, THREAD,
2471 ("cext-class_cp_index change: %d to %d", cur_index, new_index));
2472 cext_table[j].class_cp_index = (u2)new_index;
2473 }
2474 } // end for each checked exception table entry
2475 } // end if there are checked exception table entries
2476
2477 // Update each catch type index in the method's exception table
2478 // to use new constant pool indices as needed. The exception table
2479 // holds quadruple entries of the form:
2480 // (beg_bci, end_bci, handler_bci, klass_index)
2481 const int beg_bci_offset = 0;
2482 const int end_bci_offset = 1;
2483 const int handler_bci_offset = 2;
2484 const int klass_index_offset = 3;
2485 const int entry_size = 4;
2486
2487 typeArrayHandle ex_table (THREAD, method->exception_table());
2488 int ext_length = ex_table->length();
2489 assert(ext_length % entry_size == 0, "exception table format has changed");
2490
2491 for (int j = 0; j < ext_length; j += entry_size) {
2492 int cur_index = ex_table->int_at(j + klass_index_offset);
2493 int new_index = find_new_index(cur_index);
2494 if (new_index != 0) {
2495 RC_TRACE_WITH_THREAD(0x00080000, THREAD,
2496 ("ext-klass_index change: %d to %d", cur_index, new_index));
2497 ex_table->int_at_put(j + klass_index_offset, new_index);
2498 }
2499 } // end for each exception table entry
2500
2501 // Update constant pool indices in the method's local variable
2502 // table to use new constant indices as needed. The local variable
2503 // table hold sextuple entries of the form:
2504 // (start_pc, length, name_index, descriptor_index, signature_index, slot)
2505 int lvt_length = method->localvariable_table_length();
2506 if (lvt_length > 0) {
2507 LocalVariableTableElement * lv_table =
2508 method->localvariable_table_start();
2509 for (int j = 0; j < lvt_length; j++) {
2510 int cur_index = lv_table[j].name_cp_index;
2511 int new_index = find_new_index(cur_index);
2512 if (new_index != 0) {
2513 RC_TRACE_WITH_THREAD(0x00080000, THREAD,
2514 ("lvt-name_cp_index change: %d to %d", cur_index, new_index));
2515 lv_table[j].name_cp_index = (u2)new_index;
2516 }
2517 cur_index = lv_table[j].descriptor_cp_index;
2518 new_index = find_new_index(cur_index);
2519 if (new_index != 0) {
2520 RC_TRACE_WITH_THREAD(0x00080000, THREAD,
2521 ("lvt-descriptor_cp_index change: %d to %d", cur_index,
2522 new_index));
2523 lv_table[j].descriptor_cp_index = (u2)new_index;
2524 }
2525 cur_index = lv_table[j].signature_cp_index;
2526 new_index = find_new_index(cur_index);
2527 if (new_index != 0) {
2528 RC_TRACE_WITH_THREAD(0x00080000, THREAD,
2529 ("lvt-signature_cp_index change: %d to %d", cur_index, new_index));
2530 lv_table[j].signature_cp_index = (u2)new_index;
2531 }
2532 } // end for each local variable table entry
2533 } // end if there are local variable table entries
2534
2535 rewrite_cp_refs_in_stack_map_table(method, THREAD);
2536 } // end for each method
2537 assert(scratch_cp()->is_conc_safe(), "Just checking");
2538 } // end set_new_constant_pool()
2539
2540
2541 // Unevolving classes may point to methods of the_class directly
2542 // from their constant pool caches, itables, and/or vtables. We
2543 // use the SystemDictionary::classes_do() facility and this helper
2544 // to fix up these pointers.
2545 //
2546 // Note: We currently don't support updating the vtable in
2547 // arrayKlassOops. See Open Issues in jvmtiRedefineClasses.hpp.
2548 void VM_RedefineClasses::adjust_cpool_cache_and_vtable(klassOop k_oop,
2549 oop initiating_loader, TRAPS) {
2550 Klass *k = k_oop->klass_part();
2551 if (k->oop_is_instance()) {
2552 HandleMark hm(THREAD);
2553 instanceKlass *ik = (instanceKlass *) k;
2554
2555 // HotSpot specific optimization! HotSpot does not currently
2556 // support delegation from the bootstrap class loader to a
2557 // user-defined class loader. This means that if the bootstrap
2558 // class loader is the initiating class loader, then it will also
2559 // be the defining class loader. This also means that classes
2560 // loaded by the bootstrap class loader cannot refer to classes
2561 // loaded by a user-defined class loader. Note: a user-defined
2562 // class loader can delegate to the bootstrap class loader.
2563 //
2564 // If the current class being redefined has a user-defined class
2565 // loader as its defining class loader, then we can skip all
2566 // classes loaded by the bootstrap class loader.
2567 bool is_user_defined =
2568 instanceKlass::cast(_the_class_oop)->class_loader() != NULL;
2569 if (is_user_defined && ik->class_loader() == NULL) {
2570 return;
2571 }
2572
2573 // This is a very busy routine. We don't want too much tracing
2574 // printed out.
2575 bool trace_name_printed = false;
2576
2577 // Very noisy: only enable this call if you are trying to determine
2578 // that a specific class gets found by this routine.
2579 // RC_TRACE macro has an embedded ResourceMark
2580 // RC_TRACE_WITH_THREAD(0x00100000, THREAD,
2581 // ("adjust check: name=%s", ik->external_name()));
2582 // trace_name_printed = true;
2583
2584 // Fix the vtable embedded in the_class and subclasses of the_class,
2585 // if one exists. We discard scratch_class and we don't keep an
2586 // instanceKlass around to hold obsolete methods so we don't have
2587 // any other instanceKlass embedded vtables to update. The vtable
2588 // holds the methodOops for virtual (but not final) methods.
2589 if (ik->vtable_length() > 0 && ik->is_subtype_of(_the_class_oop)) {
2590 // ik->vtable() creates a wrapper object; rm cleans it up
2591 ResourceMark rm(THREAD);
2592 ik->vtable()->adjust_method_entries(_matching_old_methods,
2593 _matching_new_methods,
2594 _matching_methods_length,
2595 &trace_name_printed);
2596 }
2597
2598 // If the current class has an itable and we are either redefining an
2599 // interface or if the current class is a subclass of the_class, then
2600 // we potentially have to fix the itable. If we are redefining an
2601 // interface, then we have to call adjust_method_entries() for
2602 // every instanceKlass that has an itable since there isn't a
2603 // subclass relationship between an interface and an instanceKlass.
2604 if (ik->itable_length() > 0 && (Klass::cast(_the_class_oop)->is_interface()
2605 || ik->is_subclass_of(_the_class_oop))) {
2606 // ik->itable() creates a wrapper object; rm cleans it up
2607 ResourceMark rm(THREAD);
2608 ik->itable()->adjust_method_entries(_matching_old_methods,
2609 _matching_new_methods,
2610 _matching_methods_length,
2611 &trace_name_printed);
2612 }
2613
2614 // The constant pools in other classes (other_cp) can refer to
2615 // methods in the_class. We have to update method information in
2616 // other_cp's cache. If other_cp has a previous version, then we
2617 // have to repeat the process for each previous version. The
2618 // constant pool cache holds the methodOops for non-virtual
2619 // methods and for virtual, final methods.
2620 //
2621 // Special case: if the current class is the_class, then new_cp
2622 // has already been attached to the_class and old_cp has already
2623 // been added as a previous version. The new_cp doesn't have any
2624 // cached references to old methods so it doesn't need to be
2625 // updated. We can simply start with the previous version(s) in
2626 // that case.
2627 constantPoolHandle other_cp;
2628 constantPoolCacheOop cp_cache;
2629
2630 if (k_oop != _the_class_oop) {
2631 // this klass' constant pool cache may need adjustment
2632 other_cp = constantPoolHandle(ik->constants());
2633 cp_cache = other_cp->cache();
2634 if (cp_cache != NULL) {
2635 cp_cache->adjust_method_entries(_matching_old_methods,
2636 _matching_new_methods,
2637 _matching_methods_length,
2638 &trace_name_printed);
2639 }
2640 }
2641 {
2642 ResourceMark rm(THREAD);
2643 // PreviousVersionInfo objects returned via PreviousVersionWalker
2644 // contain a GrowableArray of handles. We have to clean up the
2645 // GrowableArray _after_ the PreviousVersionWalker destructor
2646 // has destroyed the handles.
2647 {
2648 // the previous versions' constant pool caches may need adjustment
2649 PreviousVersionWalker pvw(ik);
2650 for (PreviousVersionInfo * pv_info = pvw.next_previous_version();
2651 pv_info != NULL; pv_info = pvw.next_previous_version()) {
2652 other_cp = pv_info->prev_constant_pool_handle();
2653 cp_cache = other_cp->cache();
2654 if (cp_cache != NULL) {
2655 cp_cache->adjust_method_entries(_matching_old_methods,
2656 _matching_new_methods,
2657 _matching_methods_length,
2658 &trace_name_printed);
2659 }
2660 }
2661 } // pvw is cleaned up
2662 } // rm is cleaned up
2663 }
2664 }
2665
2666 void VM_RedefineClasses::update_jmethod_ids() {
2667 for (int j = 0; j < _matching_methods_length; ++j) {
2668 methodOop old_method = _matching_old_methods[j];
2669 jmethodID jmid = old_method->find_jmethod_id_or_null();
2670 if (jmid != NULL) {
2671 // There is a jmethodID, change it to point to the new method
2672 methodHandle new_method_h(_matching_new_methods[j]);
2673 JNIHandles::change_method_associated_with_jmethod_id(jmid, new_method_h);
2674 assert(JNIHandles::resolve_jmethod_id(jmid) == _matching_new_methods[j],
2675 "should be replaced");
2676 }
2677 }
2678 }
2679
2680 void VM_RedefineClasses::check_methods_and_mark_as_obsolete(
2681 BitMap *emcp_methods, int * emcp_method_count_p) {
2682 *emcp_method_count_p = 0;
2683 int obsolete_count = 0;
2684 int old_index = 0;
2685 for (int j = 0; j < _matching_methods_length; ++j, ++old_index) {
2686 methodOop old_method = _matching_old_methods[j];
2687 methodOop new_method = _matching_new_methods[j];
2688 methodOop old_array_method;
2689
2690 // Maintain an old_index into the _old_methods array by skipping
2691 // deleted methods
2692 while ((old_array_method = (methodOop) _old_methods->obj_at(old_index))
2693 != old_method) {
2694 ++old_index;
2695 }
2696
2697 if (MethodComparator::methods_EMCP(old_method, new_method)) {
2698 // The EMCP definition from JSR-163 requires the bytecodes to be
2699 // the same with the exception of constant pool indices which may
2700 // differ. However, the constants referred to by those indices
2701 // must be the same.
2702 //
2703 // We use methods_EMCP() for comparison since constant pool
2704 // merging can remove duplicate constant pool entries that were
2705 // present in the old method and removed from the rewritten new
2706 // method. A faster binary comparison function would consider the
2707 // old and new methods to be different when they are actually
2708 // EMCP.
2709 //
2710 // The old and new methods are EMCP and you would think that we
2711 // could get rid of one of them here and now and save some space.
2712 // However, the concept of EMCP only considers the bytecodes and
2713 // the constant pool entries in the comparison. Other things,
2714 // e.g., the line number table (LNT) or the local variable table
2715 // (LVT) don't count in the comparison. So the new (and EMCP)
2716 // method can have a new LNT that we need so we can't just
2717 // overwrite the new method with the old method.
2718 //
2719 // When this routine is called, we have already attached the new
2720 // methods to the_class so the old methods are effectively
2721 // overwritten. However, if an old method is still executing,
2722 // then the old method cannot be collected until sometime after
2723 // the old method call has returned. So the overwriting of old
2724 // methods by new methods will save us space except for those
2725 // (hopefully few) old methods that are still executing.
2726 //
2727 // A method refers to a constMethodOop and this presents another
2728 // possible avenue to space savings. The constMethodOop in the
2729 // new method contains possibly new attributes (LNT, LVT, etc).
2730 // At first glance, it seems possible to save space by replacing
2731 // the constMethodOop in the old method with the constMethodOop
2732 // from the new method. The old and new methods would share the
2733 // same constMethodOop and we would save the space occupied by
2734 // the old constMethodOop. However, the constMethodOop contains
2735 // a back reference to the containing method. Sharing the
2736 // constMethodOop between two methods could lead to confusion in
2737 // the code that uses the back reference. This would lead to
2738 // brittle code that could be broken in non-obvious ways now or
2739 // in the future.
2740 //
2741 // Another possibility is to copy the constMethodOop from the new
2742 // method to the old method and then overwrite the new method with
2743 // the old method. Since the constMethodOop contains the bytecodes
2744 // for the method embedded in the oop, this option would change
2745 // the bytecodes out from under any threads executing the old
2746 // method and make the thread's bcp invalid. Since EMCP requires
2747 // that the bytecodes be the same modulo constant pool indices, it
2748 // is straight forward to compute the correct new bcp in the new
2749 // constMethodOop from the old bcp in the old constMethodOop. The
2750 // time consuming part would be searching all the frames in all
2751 // of the threads to find all of the calls to the old method.
2752 //
2753 // It looks like we will have to live with the limited savings
2754 // that we get from effectively overwriting the old methods
2755 // when the new methods are attached to the_class.
2756
2757 // track which methods are EMCP for add_previous_version() call
2758 emcp_methods->set_bit(old_index);
2759 (*emcp_method_count_p)++;
2760
2761 // An EMCP method is _not_ obsolete. An obsolete method has a
2762 // different jmethodID than the current method. An EMCP method
2763 // has the same jmethodID as the current method. Having the
2764 // same jmethodID for all EMCP versions of a method allows for
2765 // a consistent view of the EMCP methods regardless of which
2766 // EMCP method you happen to have in hand. For example, a
2767 // breakpoint set in one EMCP method will work for all EMCP
2768 // versions of the method including the current one.
2769 } else {
2770 // mark obsolete methods as such
2771 old_method->set_is_obsolete();
2772 obsolete_count++;
2773
2774 // obsolete methods need a unique idnum
2775 u2 num = instanceKlass::cast(_the_class_oop)->next_method_idnum();
2776 if (num != constMethodOopDesc::UNSET_IDNUM) {
2777 // u2 old_num = old_method->method_idnum();
2778 old_method->set_method_idnum(num);
2779 // TO DO: attach obsolete annotations to obsolete method's new idnum
2780 }
2781 // With tracing we try not to "yack" too much. The position of
2782 // this trace assumes there are fewer obsolete methods than
2783 // EMCP methods.
2784 RC_TRACE(0x00000100, ("mark %s(%s) as obsolete",
2785 old_method->name()->as_C_string(),
2786 old_method->signature()->as_C_string()));
2787 }
2788 old_method->set_is_old();
2789 }
2790 for (int i = 0; i < _deleted_methods_length; ++i) {
2791 methodOop old_method = _deleted_methods[i];
2792
2793 assert(old_method->vtable_index() < 0,
2794 "cannot delete methods with vtable entries");;
2795
2796 // Mark all deleted methods as old and obsolete
2797 old_method->set_is_old();
2798 old_method->set_is_obsolete();
2799 ++obsolete_count;
2800 // With tracing we try not to "yack" too much. The position of
2801 // this trace assumes there are fewer obsolete methods than
2802 // EMCP methods.
2803 RC_TRACE(0x00000100, ("mark deleted %s(%s) as obsolete",
2804 old_method->name()->as_C_string(),
2805 old_method->signature()->as_C_string()));
2806 }
2807 assert((*emcp_method_count_p + obsolete_count) == _old_methods->length(),
2808 "sanity check");
2809 RC_TRACE(0x00000100, ("EMCP_cnt=%d, obsolete_cnt=%d", *emcp_method_count_p,
2810 obsolete_count));
2811 }
2812
2813 // This internal class transfers the native function registration from old methods
2814 // to new methods. It is designed to handle both the simple case of unchanged
2815 // native methods and the complex cases of native method prefixes being added and/or
2816 // removed.
2817 // It expects only to be used during the VM_RedefineClasses op (a safepoint).
2818 //
2819 // This class is used after the new methods have been installed in "the_class".
2820 //
2821 // So, for example, the following must be handled. Where 'm' is a method and
2822 // a number followed by an underscore is a prefix.
2823 //
2824 // Old Name New Name
2825 // Simple transfer to new method m -> m
2826 // Add prefix m -> 1_m
2827 // Remove prefix 1_m -> m
2828 // Simultaneous add of prefixes m -> 3_2_1_m
2829 // Simultaneous removal of prefixes 3_2_1_m -> m
2830 // Simultaneous add and remove 1_m -> 2_m
2831 // Same, caused by prefix removal only 3_2_1_m -> 3_2_m
2832 //
2833 class TransferNativeFunctionRegistration {
2834 private:
2835 instanceKlassHandle the_class;
2836 int prefix_count;
2837 char** prefixes;
2838
2839 // Recursively search the binary tree of possibly prefixed method names.
2840 // Iteration could be used if all agents were well behaved. Full tree walk is
2841 // more resilent to agents not cleaning up intermediate methods.
2842 // Branch at each depth in the binary tree is:
2843 // (1) without the prefix.
2844 // (2) with the prefix.
2845 // where 'prefix' is the prefix at that 'depth' (first prefix, second prefix,...)
2846 methodOop search_prefix_name_space(int depth, char* name_str, size_t name_len,
2847 symbolOop signature) {
2848 symbolOop name_symbol = SymbolTable::probe(name_str, (int)name_len);
2849 if (name_symbol != NULL) {
2850 methodOop method = Klass::cast(the_class())->lookup_method(name_symbol, signature);
2851 if (method != NULL) {
2852 // Even if prefixed, intermediate methods must exist.
2853 if (method->is_native()) {
2854 // Wahoo, we found a (possibly prefixed) version of the method, return it.
2855 return method;
2856 }
2857 if (depth < prefix_count) {
2858 // Try applying further prefixes (other than this one).
2859 method = search_prefix_name_space(depth+1, name_str, name_len, signature);
2860 if (method != NULL) {
2861 return method; // found
2862 }
2863
2864 // Try adding this prefix to the method name and see if it matches
2865 // another method name.
2866 char* prefix = prefixes[depth];
2867 size_t prefix_len = strlen(prefix);
2868 size_t trial_len = name_len + prefix_len;
2869 char* trial_name_str = NEW_RESOURCE_ARRAY(char, trial_len + 1);
2870 strcpy(trial_name_str, prefix);
2871 strcat(trial_name_str, name_str);
2872 method = search_prefix_name_space(depth+1, trial_name_str, trial_len,
2873 signature);
2874 if (method != NULL) {
2875 // If found along this branch, it was prefixed, mark as such
2876 method->set_is_prefixed_native();
2877 return method; // found
2878 }
2879 }
2880 }
2881 }
2882 return NULL; // This whole branch bore nothing
2883 }
2884
2885 // Return the method name with old prefixes stripped away.
2886 char* method_name_without_prefixes(methodOop method) {
2887 symbolOop name = method->name();
2888 char* name_str = name->as_utf8();
2889
2890 // Old prefixing may be defunct, strip prefixes, if any.
2891 for (int i = prefix_count-1; i >= 0; i--) {
2892 char* prefix = prefixes[i];
2893 size_t prefix_len = strlen(prefix);
2894 if (strncmp(prefix, name_str, prefix_len) == 0) {
2895 name_str += prefix_len;
2896 }
2897 }
2898 return name_str;
2899 }
2900
2901 // Strip any prefixes off the old native method, then try to find a
2902 // (possibly prefixed) new native that matches it.
2903 methodOop strip_and_search_for_new_native(methodOop method) {
2904 ResourceMark rm;
2905 char* name_str = method_name_without_prefixes(method);
2906 return search_prefix_name_space(0, name_str, strlen(name_str),
2907 method->signature());
2908 }
2909
2910 public:
2911
2912 // Construct a native method transfer processor for this class.
2913 TransferNativeFunctionRegistration(instanceKlassHandle _the_class) {
2914 assert(SafepointSynchronize::is_at_safepoint(), "sanity check");
2915
2916 the_class = _the_class;
2917 prefixes = JvmtiExport::get_all_native_method_prefixes(&prefix_count);
2918 }
2919
2920 // Attempt to transfer any of the old or deleted methods that are native
2921 void transfer_registrations(methodOop* old_methods, int methods_length) {
2922 for (int j = 0; j < methods_length; j++) {
2923 methodOop old_method = old_methods[j];
2924
2925 if (old_method->is_native() && old_method->has_native_function()) {
2926 methodOop new_method = strip_and_search_for_new_native(old_method);
2927 if (new_method != NULL) {
2928 // Actually set the native function in the new method.
2929 // Redefine does not send events (except CFLH), certainly not this
2930 // behind the scenes re-registration.
2931 new_method->set_native_function(old_method->native_function(),
2932 !methodOopDesc::native_bind_event_is_interesting);
2933 }
2934 }
2935 }
2936 }
2937 };
2938
2939 // Don't lose the association between a native method and its JNI function.
2940 void VM_RedefineClasses::transfer_old_native_function_registrations(instanceKlassHandle the_class) {
2941 TransferNativeFunctionRegistration transfer(the_class);
2942 transfer.transfer_registrations(_deleted_methods, _deleted_methods_length);
2943 transfer.transfer_registrations(_matching_old_methods, _matching_methods_length);
2944 }
2945
2946 // Deoptimize all compiled code that depends on this class.
2947 //
2948 // If the can_redefine_classes capability is obtained in the onload
2949 // phase then the compiler has recorded all dependencies from startup.
2950 // In that case we need only deoptimize and throw away all compiled code
2951 // that depends on the class.
2952 //
2953 // If can_redefine_classes is obtained sometime after the onload
2954 // phase then the dependency information may be incomplete. In that case
2955 // the first call to RedefineClasses causes all compiled code to be
2956 // thrown away. As can_redefine_classes has been obtained then
2957 // all future compilations will record dependencies so second and
2958 // subsequent calls to RedefineClasses need only throw away code
2959 // that depends on the class.
2960 //
2961 void VM_RedefineClasses::flush_dependent_code(instanceKlassHandle k_h, TRAPS) {
2962 assert_locked_or_safepoint(Compile_lock);
2963
2964 // All dependencies have been recorded from startup or this is a second or
2965 // subsequent use of RedefineClasses
2966 if (JvmtiExport::all_dependencies_are_recorded()) {
2967 Universe::flush_evol_dependents_on(k_h);
2968 } else {
2969 CodeCache::mark_all_nmethods_for_deoptimization();
2970
2971 ResourceMark rm(THREAD);
2972 DeoptimizationMarker dm;
2973
2974 // Deoptimize all activations depending on marked nmethods
2975 Deoptimization::deoptimize_dependents();
2976
2977 // Make the dependent methods not entrant (in VM_Deoptimize they are made zombies)
2978 CodeCache::make_marked_nmethods_not_entrant();
2979
2980 // From now on we know that the dependency information is complete
2981 JvmtiExport::set_all_dependencies_are_recorded(true);
2982 }
2983 }
2984
2985 void VM_RedefineClasses::compute_added_deleted_matching_methods() {
2986 methodOop old_method;
2987 methodOop new_method;
2988
2989 _matching_old_methods = NEW_RESOURCE_ARRAY(methodOop, _old_methods->length());
2990 _matching_new_methods = NEW_RESOURCE_ARRAY(methodOop, _old_methods->length());
2991 _added_methods = NEW_RESOURCE_ARRAY(methodOop, _new_methods->length());
2992 _deleted_methods = NEW_RESOURCE_ARRAY(methodOop, _old_methods->length());
2993
2994 _matching_methods_length = 0;
2995 _deleted_methods_length = 0;
2996 _added_methods_length = 0;
2997
2998 int nj = 0;
2999 int oj = 0;
3000 while (true) {
3001 if (oj >= _old_methods->length()) {
3002 if (nj >= _new_methods->length()) {
3003 break; // we've looked at everything, done
3004 }
3005 // New method at the end
3006 new_method = (methodOop) _new_methods->obj_at(nj);
3007 _added_methods[_added_methods_length++] = new_method;
3008 ++nj;
3009 } else if (nj >= _new_methods->length()) {
3010 // Old method, at the end, is deleted
3011 old_method = (methodOop) _old_methods->obj_at(oj);
3012 _deleted_methods[_deleted_methods_length++] = old_method;
3013 ++oj;
3014 } else {
3015 old_method = (methodOop) _old_methods->obj_at(oj);
3016 new_method = (methodOop) _new_methods->obj_at(nj);
3017 if (old_method->name() == new_method->name()) {
3018 if (old_method->signature() == new_method->signature()) {
3019 _matching_old_methods[_matching_methods_length ] = old_method;
3020 _matching_new_methods[_matching_methods_length++] = new_method;
3021 ++nj;
3022 ++oj;
3023 } else {
3024 // added overloaded have already been moved to the end,
3025 // so this is a deleted overloaded method
3026 _deleted_methods[_deleted_methods_length++] = old_method;
3027 ++oj;
3028 }
3029 } else { // names don't match
3030 if (old_method->name()->fast_compare(new_method->name()) > 0) {
3031 // new method
3032 _added_methods[_added_methods_length++] = new_method;
3033 ++nj;
3034 } else {
3035 // deleted method
3036 _deleted_methods[_deleted_methods_length++] = old_method;
3037 ++oj;
3038 }
3039 }
3040 }
3041 }
3042 assert(_matching_methods_length + _deleted_methods_length == _old_methods->length(), "sanity");
3043 assert(_matching_methods_length + _added_methods_length == _new_methods->length(), "sanity");
3044 }
3045
3046
3047
3048 // Install the redefinition of a class:
3049 // - house keeping (flushing breakpoints and caches, deoptimizing
3050 // dependent compiled code)
3051 // - replacing parts in the_class with parts from scratch_class
3052 // - adding a weak reference to track the obsolete but interesting
3053 // parts of the_class
3054 // - adjusting constant pool caches and vtables in other classes
3055 // that refer to methods in the_class. These adjustments use the
3056 // SystemDictionary::classes_do() facility which only allows
3057 // a helper method to be specified. The interesting parameters
3058 // that we would like to pass to the helper method are saved in
3059 // static global fields in the VM operation.
3060 void VM_RedefineClasses::redefine_single_class(jclass the_jclass,
3061 instanceKlassHandle scratch_class, TRAPS) {
3062
3063 RC_TIMER_START(_timer_rsc_phase1);
3064
3065 oop the_class_mirror = JNIHandles::resolve_non_null(the_jclass);
3066 klassOop the_class_oop = java_lang_Class::as_klassOop(the_class_mirror);
3067 instanceKlassHandle the_class = instanceKlassHandle(THREAD, the_class_oop);
3068
3069 #ifndef JVMTI_KERNEL
3070 // Remove all breakpoints in methods of this class
3071 JvmtiBreakpoints& jvmti_breakpoints = JvmtiCurrentBreakpoints::get_jvmti_breakpoints();
3072 jvmti_breakpoints.clearall_in_class_at_safepoint(the_class_oop);
3073 #endif // !JVMTI_KERNEL
3074
3075 if (the_class_oop == Universe::reflect_invoke_cache()->klass()) {
3076 // We are redefining java.lang.reflect.Method. Method.invoke() is
3077 // cached and users of the cache care about each active version of
3078 // the method so we have to track this previous version.
3079 // Do this before methods get switched
3080 Universe::reflect_invoke_cache()->add_previous_version(
3081 the_class->method_with_idnum(Universe::reflect_invoke_cache()->method_idnum()));
3082 }
3083
3084 // Deoptimize all compiled code that depends on this class
3085 flush_dependent_code(the_class, THREAD);
3086
3087 _old_methods = the_class->methods();
3088 _new_methods = scratch_class->methods();
3089 _the_class_oop = the_class_oop;
3090 compute_added_deleted_matching_methods();
3091 update_jmethod_ids();
3092
3093 // Attach new constant pool to the original klass. The original
3094 // klass still refers to the old constant pool (for now).
3095 scratch_class->constants()->set_pool_holder(the_class());
3096
3097 #if 0
3098 // In theory, with constant pool merging in place we should be able
3099 // to save space by using the new, merged constant pool in place of
3100 // the old constant pool(s). By "pool(s)" I mean the constant pool in
3101 // the klass version we are replacing now and any constant pool(s) in
3102 // previous versions of klass. Nice theory, doesn't work in practice.
3103 // When this code is enabled, even simple programs throw NullPointer
3104 // exceptions. I'm guessing that this is caused by some constant pool
3105 // cache difference between the new, merged constant pool and the
3106 // constant pool that was just being used by the klass. I'm keeping
3107 // this code around to archive the idea, but the code has to remain
3108 // disabled for now.
3109
3110 // Attach each old method to the new constant pool. This can be
3111 // done here since we are past the bytecode verification and
3112 // constant pool optimization phases.
3113 for (int i = _old_methods->length() - 1; i >= 0; i--) {
3114 methodOop method = (methodOop)_old_methods->obj_at(i);
3115 method->set_constants(scratch_class->constants());
3116 }
3117
3118 {
3119 // walk all previous versions of the klass
3120 instanceKlass *ik = (instanceKlass *)the_class()->klass_part();
3121 PreviousVersionWalker pvw(ik);
3122 instanceKlassHandle ikh;
3123 do {
3124 ikh = pvw.next_previous_version();
3125 if (!ikh.is_null()) {
3126 ik = ikh();
3127
3128 // attach previous version of klass to the new constant pool
3129 ik->set_constants(scratch_class->constants());
3130
3131 // Attach each method in the previous version of klass to the
3132 // new constant pool
3133 objArrayOop prev_methods = ik->methods();
3134 for (int i = prev_methods->length() - 1; i >= 0; i--) {
3135 methodOop method = (methodOop)prev_methods->obj_at(i);
3136 method->set_constants(scratch_class->constants());
3137 }
3138 }
3139 } while (!ikh.is_null());
3140 }
3141 #endif
3142
3143 // Replace methods and constantpool
3144 the_class->set_methods(_new_methods);
3145 scratch_class->set_methods(_old_methods); // To prevent potential GCing of the old methods,
3146 // and to be able to undo operation easily.
3147
3148 constantPoolOop old_constants = the_class->constants();
3149 the_class->set_constants(scratch_class->constants());
3150 scratch_class->set_constants(old_constants); // See the previous comment.
3151 #if 0
3152 // We are swapping the guts of "the new class" with the guts of "the
3153 // class". Since the old constant pool has just been attached to "the
3154 // new class", it seems logical to set the pool holder in the old
3155 // constant pool also. However, doing this will change the observable
3156 // class hierarchy for any old methods that are still executing. A
3157 // method can query the identity of its "holder" and this query uses
3158 // the method's constant pool link to find the holder. The change in
3159 // holding class from "the class" to "the new class" can confuse
3160 // things.
3161 //
3162 // Setting the old constant pool's holder will also cause
3163 // verification done during vtable initialization below to fail.
3164 // During vtable initialization, the vtable's class is verified to be
3165 // a subtype of the method's holder. The vtable's class is "the
3166 // class" and the method's holder is gotten from the constant pool
3167 // link in the method itself. For "the class"'s directly implemented
3168 // methods, the method holder is "the class" itself (as gotten from
3169 // the new constant pool). The check works fine in this case. The
3170 // check also works fine for methods inherited from super classes.
3171 //
3172 // Miranda methods are a little more complicated. A miranda method is
3173 // provided by an interface when the class implementing the interface
3174 // does not provide its own method. These interfaces are implemented
3175 // internally as an instanceKlass. These special instanceKlasses
3176 // share the constant pool of the class that "implements" the
3177 // interface. By sharing the constant pool, the method holder of a
3178 // miranda method is the class that "implements" the interface. In a
3179 // non-redefine situation, the subtype check works fine. However, if
3180 // the old constant pool's pool holder is modified, then the check
3181 // fails because there is no class hierarchy relationship between the
3182 // vtable's class and "the new class".
3183
3184 old_constants->set_pool_holder(scratch_class());
3185 #endif
3186
3187 // track which methods are EMCP for add_previous_version() call below
3188 BitMap emcp_methods(_old_methods->length());
3189 int emcp_method_count = 0;
3190 emcp_methods.clear(); // clears 0..(length() - 1)
3191 check_methods_and_mark_as_obsolete(&emcp_methods, &emcp_method_count);
3192 transfer_old_native_function_registrations(the_class);
3193
3194 // The class file bytes from before any retransformable agents mucked
3195 // with them was cached on the scratch class, move to the_class.
3196 // Note: we still want to do this if nothing needed caching since it
3197 // should get cleared in the_class too.
3198 the_class->set_cached_class_file(scratch_class->get_cached_class_file_bytes(),
3199 scratch_class->get_cached_class_file_len());
3200
3201 // Replace inner_classes
3202 typeArrayOop old_inner_classes = the_class->inner_classes();
3203 the_class->set_inner_classes(scratch_class->inner_classes());
3204 scratch_class->set_inner_classes(old_inner_classes);
3205
3206 // Initialize the vtable and interface table after
3207 // methods have been rewritten
3208 {
3209 ResourceMark rm(THREAD);
3210 // no exception should happen here since we explicitly
3211 // do not check loader constraints.
3212 // compare_and_normalize_class_versions has already checked:
3213 // - classloaders unchanged, signatures unchanged
3214 // - all instanceKlasses for redefined classes reused & contents updated
3215 the_class->vtable()->initialize_vtable(false, THREAD);
3216 the_class->itable()->initialize_itable(false, THREAD);
3217 assert(!HAS_PENDING_EXCEPTION || (THREAD->pending_exception()->is_a(SystemDictionary::ThreadDeath_klass())), "redefine exception");
3218 }
3219
3220 // Leave arrays of jmethodIDs and itable index cache unchanged
3221
3222 // Copy the "source file name" attribute from new class version
3223 the_class->set_source_file_name(scratch_class->source_file_name());
3224
3225 // Copy the "source debug extension" attribute from new class version
3226 the_class->set_source_debug_extension(
3227 scratch_class->source_debug_extension());
3228
3229 // Use of javac -g could be different in the old and the new
3230 if (scratch_class->access_flags().has_localvariable_table() !=
3231 the_class->access_flags().has_localvariable_table()) {
3232
3233 AccessFlags flags = the_class->access_flags();
3234 if (scratch_class->access_flags().has_localvariable_table()) {
3235 flags.set_has_localvariable_table();
3236 } else {
3237 flags.clear_has_localvariable_table();
3238 }
3239 the_class->set_access_flags(flags);
3240 }
3241
3242 // Replace class annotation fields values
3243 typeArrayOop old_class_annotations = the_class->class_annotations();
3244 the_class->set_class_annotations(scratch_class->class_annotations());
3245 scratch_class->set_class_annotations(old_class_annotations);
3246
3247 // Replace fields annotation fields values
3248 objArrayOop old_fields_annotations = the_class->fields_annotations();
3249 the_class->set_fields_annotations(scratch_class->fields_annotations());
3250 scratch_class->set_fields_annotations(old_fields_annotations);
3251
3252 // Replace methods annotation fields values
3253 objArrayOop old_methods_annotations = the_class->methods_annotations();
3254 the_class->set_methods_annotations(scratch_class->methods_annotations());
3255 scratch_class->set_methods_annotations(old_methods_annotations);
3256
3257 // Replace methods parameter annotation fields values
3258 objArrayOop old_methods_parameter_annotations =
3259 the_class->methods_parameter_annotations();
3260 the_class->set_methods_parameter_annotations(
3261 scratch_class->methods_parameter_annotations());
3262 scratch_class->set_methods_parameter_annotations(old_methods_parameter_annotations);
3263
3264 // Replace methods default annotation fields values
3265 objArrayOop old_methods_default_annotations =
3266 the_class->methods_default_annotations();
3267 the_class->set_methods_default_annotations(
3268 scratch_class->methods_default_annotations());
3269 scratch_class->set_methods_default_annotations(old_methods_default_annotations);
3270
3271 // Replace minor version number of class file
3272 u2 old_minor_version = the_class->minor_version();
3273 the_class->set_minor_version(scratch_class->minor_version());
3274 scratch_class->set_minor_version(old_minor_version);
3275
3276 // Replace major version number of class file
3277 u2 old_major_version = the_class->major_version();
3278 the_class->set_major_version(scratch_class->major_version());
3279 scratch_class->set_major_version(old_major_version);
3280
3281 // Replace CP indexes for class and name+type of enclosing method
3282 u2 old_class_idx = the_class->enclosing_method_class_index();
3283 u2 old_method_idx = the_class->enclosing_method_method_index();
3284 the_class->set_enclosing_method_indices(
3285 scratch_class->enclosing_method_class_index(),
3286 scratch_class->enclosing_method_method_index());
3287 scratch_class->set_enclosing_method_indices(old_class_idx, old_method_idx);
3288
3289 // keep track of previous versions of this class
3290 the_class->add_previous_version(scratch_class, &emcp_methods,
3291 emcp_method_count);
3292
3293 RC_TIMER_STOP(_timer_rsc_phase1);
3294 RC_TIMER_START(_timer_rsc_phase2);
3295
3296 // Adjust constantpool caches and vtables for all classes
3297 // that reference methods of the evolved class.
3298 SystemDictionary::classes_do(adjust_cpool_cache_and_vtable, THREAD);
3299
3300 if (the_class->oop_map_cache() != NULL) {
3301 // Flush references to any obsolete methods from the oop map cache
3302 // so that obsolete methods are not pinned.
3303 the_class->oop_map_cache()->flush_obsolete_entries();
3304 }
3305
3306 // increment the classRedefinedCount field in the_class and in any
3307 // direct and indirect subclasses of the_class
3308 increment_class_counter((instanceKlass *)the_class()->klass_part(), THREAD);
3309
3310 // RC_TRACE macro has an embedded ResourceMark
3311 RC_TRACE_WITH_THREAD(0x00000001, THREAD,
3312 ("redefined name=%s, count=%d (avail_mem=" UINT64_FORMAT "K)",
3313 the_class->external_name(),
3314 java_lang_Class::classRedefinedCount(the_class_mirror),
3315 os::available_memory() >> 10));
3316
3317 RC_TIMER_STOP(_timer_rsc_phase2);
3318 } // end redefine_single_class()
3319
3320
3321 // Increment the classRedefinedCount field in the specific instanceKlass
3322 // and in all direct and indirect subclasses.
3323 void VM_RedefineClasses::increment_class_counter(instanceKlass *ik, TRAPS) {
3324 oop class_mirror = ik->java_mirror();
3325 klassOop class_oop = java_lang_Class::as_klassOop(class_mirror);
3326 int new_count = java_lang_Class::classRedefinedCount(class_mirror) + 1;
3327 java_lang_Class::set_classRedefinedCount(class_mirror, new_count);
3328
3329 if (class_oop != _the_class_oop) {
3330 // _the_class_oop count is printed at end of redefine_single_class()
3331 RC_TRACE_WITH_THREAD(0x00000008, THREAD,
3332 ("updated count in subclass=%s to %d", ik->external_name(), new_count));
3333 }
3334
3335 for (Klass *subk = ik->subklass(); subk != NULL;
3336 subk = subk->next_sibling()) {
3337 klassOop sub = subk->as_klassOop();
3338 instanceKlass *subik = (instanceKlass *)sub->klass_part();
3339
3340 // recursively do subclasses of the current subclass
3341 increment_class_counter(subik, THREAD);
3342 }
3343 }
3344
3345 #ifndef PRODUCT
3346 void VM_RedefineClasses::check_class(klassOop k_oop,
3347 oop initiating_loader, TRAPS) {
3348 Klass *k = k_oop->klass_part();
3349 if (k->oop_is_instance()) {
3350 HandleMark hm(THREAD);
3351 instanceKlass *ik = (instanceKlass *) k;
3352
3353 if (ik->vtable_length() > 0) {
3354 ResourceMark rm(THREAD);
3355 if (!ik->vtable()->check_no_old_entries()) {
3356 tty->print_cr("klassVtable::check_no_old_entries failure -- OLD method found -- class: %s", ik->signature_name());
3357 ik->vtable()->dump_vtable();
3358 dump_methods();
3359 assert(false, "OLD method found");
3360 }
3361 }
3362 }
3363 }
3364
3365 void VM_RedefineClasses::dump_methods() {
3366 int j;
3367 tty->print_cr("_old_methods --");
3368 for (j = 0; j < _old_methods->length(); ++j) {
3369 methodOop m = (methodOop) _old_methods->obj_at(j);
3370 tty->print("%4d (%5d) ", j, m->vtable_index());
3371 m->access_flags().print_on(tty);
3372 tty->print(" -- ");
3373 m->print_name(tty);
3374 tty->cr();
3375 }
3376 tty->print_cr("_new_methods --");
3377 for (j = 0; j < _new_methods->length(); ++j) {
3378 methodOop m = (methodOop) _new_methods->obj_at(j);
3379 tty->print("%4d (%5d) ", j, m->vtable_index());
3380 m->access_flags().print_on(tty);
3381 tty->print(" -- ");
3382 m->print_name(tty);
3383 tty->cr();
3384 }
3385 tty->print_cr("_matching_(old/new)_methods --");
3386 for (j = 0; j < _matching_methods_length; ++j) {
3387 methodOop m = _matching_old_methods[j];
3388 tty->print("%4d (%5d) ", j, m->vtable_index());
3389 m->access_flags().print_on(tty);
3390 tty->print(" -- ");
3391 m->print_name(tty);
3392 tty->cr();
3393 m = _matching_new_methods[j];
3394 tty->print(" (%5d) ", m->vtable_index());
3395 m->access_flags().print_on(tty);
3396 tty->cr();
3397 }
3398 tty->print_cr("_deleted_methods --");
3399 for (j = 0; j < _deleted_methods_length; ++j) {
3400 methodOop m = _deleted_methods[j];
3401 tty->print("%4d (%5d) ", j, m->vtable_index());
3402 m->access_flags().print_on(tty);
3403 tty->print(" -- ");
3404 m->print_name(tty);
3405 tty->cr();
3406 }
3407 tty->print_cr("_added_methods --");
3408 for (j = 0; j < _added_methods_length; ++j) {
3409 methodOop m = _added_methods[j];
3410 tty->print("%4d (%5d) ", j, m->vtable_index());
3411 m->access_flags().print_on(tty);
3412 tty->print(" -- ");
3413 m->print_name(tty);
3414 tty->cr();
3415 }
3416 }
3417 #endif