1 /*
2 * Copyright (c) 2003, 2012, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
24
25 #include "precompiled.hpp"
26 #include "classfile/systemDictionary.hpp"
27 #include "classfile/verifier.hpp"
28 #include "code/codeCache.hpp"
29 #include "interpreter/oopMapCache.hpp"
30 #include "interpreter/rewriter.hpp"
31 #include "memory/gcLocker.hpp"
32 #include "memory/universe.inline.hpp"
33 #include "oops/fieldStreams.hpp"
34 #include "oops/klassVtable.hpp"
35 #include "prims/jvmtiImpl.hpp"
36 #include "prims/jvmtiRedefineClasses.hpp"
37 #include "prims/methodComparator.hpp"
38 #include "runtime/deoptimization.hpp"
39 #include "runtime/relocator.hpp"
40 #include "utilities/bitMap.inline.hpp"
41
42
43 objArrayOop VM_RedefineClasses::_old_methods = NULL;
44 objArrayOop VM_RedefineClasses::_new_methods = NULL;
45 methodOop* VM_RedefineClasses::_matching_old_methods = NULL;
46 methodOop* VM_RedefineClasses::_matching_new_methods = NULL;
47 methodOop* VM_RedefineClasses::_deleted_methods = NULL;
48 methodOop* VM_RedefineClasses::_added_methods = NULL;
49 int VM_RedefineClasses::_matching_methods_length = 0;
50 int VM_RedefineClasses::_deleted_methods_length = 0;
51 int VM_RedefineClasses::_added_methods_length = 0;
52 klassOop VM_RedefineClasses::_the_class_oop = NULL;
53
54
55 VM_RedefineClasses::VM_RedefineClasses(jint class_count,
56 const jvmtiClassDefinition *class_defs,
57 JvmtiClassLoadKind class_load_kind) {
58 _class_count = class_count;
59 _class_defs = class_defs;
60 _class_load_kind = class_load_kind;
61 _res = JVMTI_ERROR_NONE;
62 }
63
64 bool VM_RedefineClasses::doit_prologue() {
65 if (_class_count == 0) {
66 _res = JVMTI_ERROR_NONE;
67 return false;
68 }
69 if (_class_defs == NULL) {
70 _res = JVMTI_ERROR_NULL_POINTER;
71 return false;
72 }
73 for (int i = 0; i < _class_count; i++) {
74 if (_class_defs[i].klass == NULL) {
75 _res = JVMTI_ERROR_INVALID_CLASS;
76 return false;
77 }
78 if (_class_defs[i].class_byte_count == 0) {
79 _res = JVMTI_ERROR_INVALID_CLASS_FORMAT;
80 return false;
81 }
82 if (_class_defs[i].class_bytes == NULL) {
83 _res = JVMTI_ERROR_NULL_POINTER;
84 return false;
85 }
86 }
87
88 // Start timer after all the sanity checks; not quite accurate, but
89 // better than adding a bunch of stop() calls.
90 RC_TIMER_START(_timer_vm_op_prologue);
91
92 // We first load new class versions in the prologue, because somewhere down the
93 // call chain it is required that the current thread is a Java thread.
94 _res = load_new_class_versions(Thread::current());
95 if (_res != JVMTI_ERROR_NONE) {
96 // Free os::malloc allocated memory in load_new_class_version.
97 os::free(_scratch_classes);
98 RC_TIMER_STOP(_timer_vm_op_prologue);
99 return false;
100 }
101
102 RC_TIMER_STOP(_timer_vm_op_prologue);
103 return true;
104 }
105
106 void VM_RedefineClasses::doit() {
107 Thread *thread = Thread::current();
108
109 if (UseSharedSpaces) {
110 // Sharing is enabled so we remap the shared readonly space to
111 // shared readwrite, private just in case we need to redefine
112 // a shared class. We do the remap during the doit() phase of
113 // the safepoint to be safer.
114 if (!CompactingPermGenGen::remap_shared_readonly_as_readwrite()) {
115 RC_TRACE_WITH_THREAD(0x00000001, thread,
116 ("failed to remap shared readonly space to readwrite, private"));
117 _res = JVMTI_ERROR_INTERNAL;
118 return;
119 }
120 }
121
122 for (int i = 0; i < _class_count; i++) {
123 redefine_single_class(_class_defs[i].klass, _scratch_classes[i], thread);
124 }
125 // Disable any dependent concurrent compilations
126 SystemDictionary::notice_modification();
127
128 // Set flag indicating that some invariants are no longer true.
129 // See jvmtiExport.hpp for detailed explanation.
130 JvmtiExport::set_has_redefined_a_class();
131
132 #ifdef ASSERT
133 SystemDictionary::classes_do(check_class, thread);
134 #endif
135 }
136
137 void VM_RedefineClasses::doit_epilogue() {
138 // Free os::malloc allocated memory.
139 // The memory allocated in redefine will be free'ed in next VM operation.
140 os::free(_scratch_classes);
141
142 if (RC_TRACE_ENABLED(0x00000004)) {
143 // Used to have separate timers for "doit" and "all", but the timer
144 // overhead skewed the measurements.
145 jlong doit_time = _timer_rsc_phase1.milliseconds() +
146 _timer_rsc_phase2.milliseconds();
147 jlong all_time = _timer_vm_op_prologue.milliseconds() + doit_time;
148
149 RC_TRACE(0x00000004, ("vm_op: all=" UINT64_FORMAT
150 " prologue=" UINT64_FORMAT " doit=" UINT64_FORMAT, all_time,
151 _timer_vm_op_prologue.milliseconds(), doit_time));
152 RC_TRACE(0x00000004,
153 ("redefine_single_class: phase1=" UINT64_FORMAT " phase2=" UINT64_FORMAT,
154 _timer_rsc_phase1.milliseconds(), _timer_rsc_phase2.milliseconds()));
155 }
156 }
157
158 bool VM_RedefineClasses::is_modifiable_class(oop klass_mirror) {
159 // classes for primitives cannot be redefined
160 if (java_lang_Class::is_primitive(klass_mirror)) {
161 return false;
162 }
163 klassOop the_class_oop = java_lang_Class::as_klassOop(klass_mirror);
164 // classes for arrays cannot be redefined
165 if (the_class_oop == NULL || !Klass::cast(the_class_oop)->oop_is_instance()) {
166 return false;
167 }
168 return true;
169 }
170
171 // Append the current entry at scratch_i in scratch_cp to *merge_cp_p
172 // where the end of *merge_cp_p is specified by *merge_cp_length_p. For
173 // direct CP entries, there is just the current entry to append. For
174 // indirect and double-indirect CP entries, there are zero or more
175 // referenced CP entries along with the current entry to append.
176 // Indirect and double-indirect CP entries are handled by recursive
177 // calls to append_entry() as needed. The referenced CP entries are
178 // always appended to *merge_cp_p before the referee CP entry. These
179 // referenced CP entries may already exist in *merge_cp_p in which case
180 // there is nothing extra to append and only the current entry is
181 // appended.
182 void VM_RedefineClasses::append_entry(constantPoolHandle scratch_cp,
183 int scratch_i, constantPoolHandle *merge_cp_p, int *merge_cp_length_p,
184 TRAPS) {
185
186 // append is different depending on entry tag type
187 switch (scratch_cp->tag_at(scratch_i).value()) {
188
189 // The old verifier is implemented outside the VM. It loads classes,
190 // but does not resolve constant pool entries directly so we never
191 // see Class entries here with the old verifier. Similarly the old
192 // verifier does not like Class entries in the input constant pool.
193 // The split-verifier is implemented in the VM so it can optionally
194 // and directly resolve constant pool entries to load classes. The
195 // split-verifier can accept either Class entries or UnresolvedClass
196 // entries in the input constant pool. We revert the appended copy
197 // back to UnresolvedClass so that either verifier will be happy
198 // with the constant pool entry.
199 case JVM_CONSTANT_Class:
200 {
201 // revert the copy to JVM_CONSTANT_UnresolvedClass
202 (*merge_cp_p)->unresolved_klass_at_put(*merge_cp_length_p,
203 scratch_cp->klass_name_at(scratch_i));
204
205 if (scratch_i != *merge_cp_length_p) {
206 // The new entry in *merge_cp_p is at a different index than
207 // the new entry in scratch_cp so we need to map the index values.
208 map_index(scratch_cp, scratch_i, *merge_cp_length_p);
209 }
210 (*merge_cp_length_p)++;
211 } break;
212
213 // these are direct CP entries so they can be directly appended,
214 // but double and long take two constant pool entries
215 case JVM_CONSTANT_Double: // fall through
216 case JVM_CONSTANT_Long:
217 {
218 constantPoolOopDesc::copy_entry_to(scratch_cp, scratch_i, *merge_cp_p, *merge_cp_length_p,
219 THREAD);
220
221 if (scratch_i != *merge_cp_length_p) {
222 // The new entry in *merge_cp_p is at a different index than
223 // the new entry in scratch_cp so we need to map the index values.
224 map_index(scratch_cp, scratch_i, *merge_cp_length_p);
225 }
226 (*merge_cp_length_p) += 2;
227 } break;
228
229 // these are direct CP entries so they can be directly appended
230 case JVM_CONSTANT_Float: // fall through
231 case JVM_CONSTANT_Integer: // fall through
232 case JVM_CONSTANT_Utf8: // fall through
233
234 // This was an indirect CP entry, but it has been changed into
235 // an interned string so this entry can be directly appended.
236 case JVM_CONSTANT_String: // fall through
237
238 // These were indirect CP entries, but they have been changed into
239 // Symbol*s so these entries can be directly appended.
240 case JVM_CONSTANT_UnresolvedClass: // fall through
241 case JVM_CONSTANT_UnresolvedString:
242 {
243 constantPoolOopDesc::copy_entry_to(scratch_cp, scratch_i, *merge_cp_p, *merge_cp_length_p,
244 THREAD);
245
246 if (scratch_i != *merge_cp_length_p) {
247 // The new entry in *merge_cp_p is at a different index than
248 // the new entry in scratch_cp so we need to map the index values.
249 map_index(scratch_cp, scratch_i, *merge_cp_length_p);
250 }
251 (*merge_cp_length_p)++;
252 } break;
253
254 // this is an indirect CP entry so it needs special handling
255 case JVM_CONSTANT_NameAndType:
256 {
257 int name_ref_i = scratch_cp->name_ref_index_at(scratch_i);
258 int new_name_ref_i = 0;
259 bool match = (name_ref_i < *merge_cp_length_p) &&
260 scratch_cp->compare_entry_to(name_ref_i, *merge_cp_p, name_ref_i,
261 THREAD);
262 if (!match) {
263 // forward reference in *merge_cp_p or not a direct match
264
265 int found_i = scratch_cp->find_matching_entry(name_ref_i, *merge_cp_p,
266 THREAD);
267 if (found_i != 0) {
268 guarantee(found_i != name_ref_i,
269 "compare_entry_to() and find_matching_entry() do not agree");
270
271 // Found a matching entry somewhere else in *merge_cp_p so
272 // just need a mapping entry.
273 new_name_ref_i = found_i;
274 map_index(scratch_cp, name_ref_i, found_i);
275 } else {
276 // no match found so we have to append this entry to *merge_cp_p
277 append_entry(scratch_cp, name_ref_i, merge_cp_p, merge_cp_length_p,
278 THREAD);
279 // The above call to append_entry() can only append one entry
280 // so the post call query of *merge_cp_length_p is only for
281 // the sake of consistency.
282 new_name_ref_i = *merge_cp_length_p - 1;
283 }
284 }
285
286 int signature_ref_i = scratch_cp->signature_ref_index_at(scratch_i);
287 int new_signature_ref_i = 0;
288 match = (signature_ref_i < *merge_cp_length_p) &&
289 scratch_cp->compare_entry_to(signature_ref_i, *merge_cp_p,
290 signature_ref_i, THREAD);
291 if (!match) {
292 // forward reference in *merge_cp_p or not a direct match
293
294 int found_i = scratch_cp->find_matching_entry(signature_ref_i,
295 *merge_cp_p, THREAD);
296 if (found_i != 0) {
297 guarantee(found_i != signature_ref_i,
298 "compare_entry_to() and find_matching_entry() do not agree");
299
300 // Found a matching entry somewhere else in *merge_cp_p so
301 // just need a mapping entry.
302 new_signature_ref_i = found_i;
303 map_index(scratch_cp, signature_ref_i, found_i);
304 } else {
305 // no match found so we have to append this entry to *merge_cp_p
306 append_entry(scratch_cp, signature_ref_i, merge_cp_p,
307 merge_cp_length_p, THREAD);
308 // The above call to append_entry() can only append one entry
309 // so the post call query of *merge_cp_length_p is only for
310 // the sake of consistency.
311 new_signature_ref_i = *merge_cp_length_p - 1;
312 }
313 }
314
315 // If the referenced entries already exist in *merge_cp_p, then
316 // both new_name_ref_i and new_signature_ref_i will both be 0.
317 // In that case, all we are appending is the current entry.
318 if (new_name_ref_i == 0) {
319 new_name_ref_i = name_ref_i;
320 } else {
321 RC_TRACE(0x00080000,
322 ("NameAndType entry@%d name_ref_index change: %d to %d",
323 *merge_cp_length_p, name_ref_i, new_name_ref_i));
324 }
325 if (new_signature_ref_i == 0) {
326 new_signature_ref_i = signature_ref_i;
327 } else {
328 RC_TRACE(0x00080000,
329 ("NameAndType entry@%d signature_ref_index change: %d to %d",
330 *merge_cp_length_p, signature_ref_i, new_signature_ref_i));
331 }
332
333 (*merge_cp_p)->name_and_type_at_put(*merge_cp_length_p,
334 new_name_ref_i, new_signature_ref_i);
335 if (scratch_i != *merge_cp_length_p) {
336 // The new entry in *merge_cp_p is at a different index than
337 // the new entry in scratch_cp so we need to map the index values.
338 map_index(scratch_cp, scratch_i, *merge_cp_length_p);
339 }
340 (*merge_cp_length_p)++;
341 } break;
342
343 // this is a double-indirect CP entry so it needs special handling
344 case JVM_CONSTANT_Fieldref: // fall through
345 case JVM_CONSTANT_InterfaceMethodref: // fall through
346 case JVM_CONSTANT_Methodref:
347 {
348 int klass_ref_i = scratch_cp->uncached_klass_ref_index_at(scratch_i);
349 int new_klass_ref_i = 0;
350 bool match = (klass_ref_i < *merge_cp_length_p) &&
351 scratch_cp->compare_entry_to(klass_ref_i, *merge_cp_p, klass_ref_i,
352 THREAD);
353 if (!match) {
354 // forward reference in *merge_cp_p or not a direct match
355
356 int found_i = scratch_cp->find_matching_entry(klass_ref_i, *merge_cp_p,
357 THREAD);
358 if (found_i != 0) {
359 guarantee(found_i != klass_ref_i,
360 "compare_entry_to() and find_matching_entry() do not agree");
361
362 // Found a matching entry somewhere else in *merge_cp_p so
363 // just need a mapping entry.
364 new_klass_ref_i = found_i;
365 map_index(scratch_cp, klass_ref_i, found_i);
366 } else {
367 // no match found so we have to append this entry to *merge_cp_p
368 append_entry(scratch_cp, klass_ref_i, merge_cp_p, merge_cp_length_p,
369 THREAD);
370 // The above call to append_entry() can only append one entry
371 // so the post call query of *merge_cp_length_p is only for
372 // the sake of consistency. Without the optimization where we
373 // use JVM_CONSTANT_UnresolvedClass, then up to two entries
374 // could be appended.
375 new_klass_ref_i = *merge_cp_length_p - 1;
376 }
377 }
378
379 int name_and_type_ref_i =
380 scratch_cp->uncached_name_and_type_ref_index_at(scratch_i);
381 int new_name_and_type_ref_i = 0;
382 match = (name_and_type_ref_i < *merge_cp_length_p) &&
383 scratch_cp->compare_entry_to(name_and_type_ref_i, *merge_cp_p,
384 name_and_type_ref_i, THREAD);
385 if (!match) {
386 // forward reference in *merge_cp_p or not a direct match
387
388 int found_i = scratch_cp->find_matching_entry(name_and_type_ref_i,
389 *merge_cp_p, THREAD);
390 if (found_i != 0) {
391 guarantee(found_i != name_and_type_ref_i,
392 "compare_entry_to() and find_matching_entry() do not agree");
393
394 // Found a matching entry somewhere else in *merge_cp_p so
395 // just need a mapping entry.
396 new_name_and_type_ref_i = found_i;
397 map_index(scratch_cp, name_and_type_ref_i, found_i);
398 } else {
399 // no match found so we have to append this entry to *merge_cp_p
400 append_entry(scratch_cp, name_and_type_ref_i, merge_cp_p,
401 merge_cp_length_p, THREAD);
402 // The above call to append_entry() can append more than
403 // one entry so the post call query of *merge_cp_length_p
404 // is required in order to get the right index for the
405 // JVM_CONSTANT_NameAndType entry.
406 new_name_and_type_ref_i = *merge_cp_length_p - 1;
407 }
408 }
409
410 // If the referenced entries already exist in *merge_cp_p, then
411 // both new_klass_ref_i and new_name_and_type_ref_i will both be
412 // 0. In that case, all we are appending is the current entry.
413 if (new_klass_ref_i == 0) {
414 new_klass_ref_i = klass_ref_i;
415 }
416 if (new_name_and_type_ref_i == 0) {
417 new_name_and_type_ref_i = name_and_type_ref_i;
418 }
419
420 const char *entry_name;
421 switch (scratch_cp->tag_at(scratch_i).value()) {
422 case JVM_CONSTANT_Fieldref:
423 entry_name = "Fieldref";
424 (*merge_cp_p)->field_at_put(*merge_cp_length_p, new_klass_ref_i,
425 new_name_and_type_ref_i);
426 break;
427 case JVM_CONSTANT_InterfaceMethodref:
428 entry_name = "IFMethodref";
429 (*merge_cp_p)->interface_method_at_put(*merge_cp_length_p,
430 new_klass_ref_i, new_name_and_type_ref_i);
431 break;
432 case JVM_CONSTANT_Methodref:
433 entry_name = "Methodref";
434 (*merge_cp_p)->method_at_put(*merge_cp_length_p, new_klass_ref_i,
435 new_name_and_type_ref_i);
436 break;
437 default:
438 guarantee(false, "bad switch");
439 break;
440 }
441
442 if (klass_ref_i != new_klass_ref_i) {
443 RC_TRACE(0x00080000, ("%s entry@%d class_index changed: %d to %d",
444 entry_name, *merge_cp_length_p, klass_ref_i, new_klass_ref_i));
445 }
446 if (name_and_type_ref_i != new_name_and_type_ref_i) {
447 RC_TRACE(0x00080000,
448 ("%s entry@%d name_and_type_index changed: %d to %d",
449 entry_name, *merge_cp_length_p, name_and_type_ref_i,
450 new_name_and_type_ref_i));
451 }
452
453 if (scratch_i != *merge_cp_length_p) {
454 // The new entry in *merge_cp_p is at a different index than
455 // the new entry in scratch_cp so we need to map the index values.
456 map_index(scratch_cp, scratch_i, *merge_cp_length_p);
457 }
458 (*merge_cp_length_p)++;
459 } break;
460
461 // At this stage, Class or UnresolvedClass could be here, but not
462 // ClassIndex
463 case JVM_CONSTANT_ClassIndex: // fall through
464
465 // Invalid is used as the tag for the second constant pool entry
466 // occupied by JVM_CONSTANT_Double or JVM_CONSTANT_Long. It should
467 // not be seen by itself.
468 case JVM_CONSTANT_Invalid: // fall through
469
470 // At this stage, String or UnresolvedString could be here, but not
471 // StringIndex
472 case JVM_CONSTANT_StringIndex: // fall through
473
474 // At this stage JVM_CONSTANT_UnresolvedClassInError should not be
475 // here
476 case JVM_CONSTANT_UnresolvedClassInError: // fall through
477
478 default:
479 {
480 // leave a breadcrumb
481 jbyte bad_value = scratch_cp->tag_at(scratch_i).value();
482 ShouldNotReachHere();
483 } break;
484 } // end switch tag value
485 } // end append_entry()
486
487
488 void VM_RedefineClasses::swap_all_method_annotations(int i, int j, instanceKlassHandle scratch_class) {
489 typeArrayOop save;
490
491 save = scratch_class->get_method_annotations_of(i);
492 scratch_class->set_method_annotations_of(i, scratch_class->get_method_annotations_of(j));
493 scratch_class->set_method_annotations_of(j, save);
494
495 save = scratch_class->get_method_parameter_annotations_of(i);
496 scratch_class->set_method_parameter_annotations_of(i, scratch_class->get_method_parameter_annotations_of(j));
497 scratch_class->set_method_parameter_annotations_of(j, save);
498
499 save = scratch_class->get_method_default_annotations_of(i);
500 scratch_class->set_method_default_annotations_of(i, scratch_class->get_method_default_annotations_of(j));
501 scratch_class->set_method_default_annotations_of(j, save);
502 }
503
504
505 jvmtiError VM_RedefineClasses::compare_and_normalize_class_versions(
506 instanceKlassHandle the_class,
507 instanceKlassHandle scratch_class) {
508 int i;
509
510 // Check superclasses, or rather their names, since superclasses themselves can be
511 // requested to replace.
512 // Check for NULL superclass first since this might be java.lang.Object
513 if (the_class->super() != scratch_class->super() &&
514 (the_class->super() == NULL || scratch_class->super() == NULL ||
515 Klass::cast(the_class->super())->name() !=
516 Klass::cast(scratch_class->super())->name())) {
517 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_HIERARCHY_CHANGED;
518 }
519
520 // Check if the number, names and order of directly implemented interfaces are the same.
521 // I think in principle we should just check if the sets of names of directly implemented
522 // interfaces are the same, i.e. the order of declaration (which, however, if changed in the
523 // .java file, also changes in .class file) should not matter. However, comparing sets is
524 // technically a bit more difficult, and, more importantly, I am not sure at present that the
525 // order of interfaces does not matter on the implementation level, i.e. that the VM does not
526 // rely on it somewhere.
527 objArrayOop k_interfaces = the_class->local_interfaces();
528 objArrayOop k_new_interfaces = scratch_class->local_interfaces();
529 int n_intfs = k_interfaces->length();
530 if (n_intfs != k_new_interfaces->length()) {
531 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_HIERARCHY_CHANGED;
532 }
533 for (i = 0; i < n_intfs; i++) {
534 if (Klass::cast((klassOop) k_interfaces->obj_at(i))->name() !=
535 Klass::cast((klassOop) k_new_interfaces->obj_at(i))->name()) {
536 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_HIERARCHY_CHANGED;
537 }
538 }
539
540 // Check whether class is in the error init state.
541 if (the_class->is_in_error_state()) {
542 // TBD #5057930: special error code is needed in 1.6
543 return JVMTI_ERROR_INVALID_CLASS;
544 }
545
546 // Check whether class modifiers are the same.
547 jushort old_flags = (jushort) the_class->access_flags().get_flags();
548 jushort new_flags = (jushort) scratch_class->access_flags().get_flags();
549 if (old_flags != new_flags) {
550 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_CLASS_MODIFIERS_CHANGED;
551 }
552
553 // Check if the number, names, types and order of fields declared in these classes
554 // are the same.
555 JavaFieldStream old_fs(the_class);
556 JavaFieldStream new_fs(scratch_class);
557 for (; !old_fs.done() && !new_fs.done(); old_fs.next(), new_fs.next()) {
558 // access
559 old_flags = old_fs.access_flags().as_short();
560 new_flags = new_fs.access_flags().as_short();
561 if ((old_flags ^ new_flags) & JVM_RECOGNIZED_FIELD_MODIFIERS) {
562 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_SCHEMA_CHANGED;
563 }
564 // offset
565 if (old_fs.offset() != new_fs.offset()) {
566 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_SCHEMA_CHANGED;
567 }
568 // name and signature
569 Symbol* name_sym1 = the_class->constants()->symbol_at(old_fs.name_index());
570 Symbol* sig_sym1 = the_class->constants()->symbol_at(old_fs.signature_index());
571 Symbol* name_sym2 = scratch_class->constants()->symbol_at(new_fs.name_index());
572 Symbol* sig_sym2 = scratch_class->constants()->symbol_at(new_fs.signature_index());
573 if (name_sym1 != name_sym2 || sig_sym1 != sig_sym2) {
574 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_SCHEMA_CHANGED;
575 }
576 }
577
578 // If both streams aren't done then we have a differing number of
579 // fields.
580 if (!old_fs.done() || !new_fs.done()) {
581 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_SCHEMA_CHANGED;
582 }
583
584 // Do a parallel walk through the old and new methods. Detect
585 // cases where they match (exist in both), have been added in
586 // the new methods, or have been deleted (exist only in the
587 // old methods). The class file parser places methods in order
588 // by method name, but does not order overloaded methods by
589 // signature. In order to determine what fate befell the methods,
590 // this code places the overloaded new methods that have matching
591 // old methods in the same order as the old methods and places
592 // new overloaded methods at the end of overloaded methods of
593 // that name. The code for this order normalization is adapted
594 // from the algorithm used in instanceKlass::find_method().
595 // Since we are swapping out of order entries as we find them,
596 // we only have to search forward through the overloaded methods.
597 // Methods which are added and have the same name as an existing
598 // method (but different signature) will be put at the end of
599 // the methods with that name, and the name mismatch code will
600 // handle them.
601 objArrayHandle k_old_methods(the_class->methods());
602 objArrayHandle k_new_methods(scratch_class->methods());
603 int n_old_methods = k_old_methods->length();
604 int n_new_methods = k_new_methods->length();
605
606 int ni = 0;
607 int oi = 0;
608 while (true) {
609 methodOop k_old_method;
610 methodOop k_new_method;
611 enum { matched, added, deleted, undetermined } method_was = undetermined;
612
613 if (oi >= n_old_methods) {
614 if (ni >= n_new_methods) {
615 break; // we've looked at everything, done
616 }
617 // New method at the end
618 k_new_method = (methodOop) k_new_methods->obj_at(ni);
619 method_was = added;
620 } else if (ni >= n_new_methods) {
621 // Old method, at the end, is deleted
622 k_old_method = (methodOop) k_old_methods->obj_at(oi);
623 method_was = deleted;
624 } else {
625 // There are more methods in both the old and new lists
626 k_old_method = (methodOop) k_old_methods->obj_at(oi);
627 k_new_method = (methodOop) k_new_methods->obj_at(ni);
628 if (k_old_method->name() != k_new_method->name()) {
629 // Methods are sorted by method name, so a mismatch means added
630 // or deleted
631 if (k_old_method->name()->fast_compare(k_new_method->name()) > 0) {
632 method_was = added;
633 } else {
634 method_was = deleted;
635 }
636 } else if (k_old_method->signature() == k_new_method->signature()) {
637 // Both the name and signature match
638 method_was = matched;
639 } else {
640 // The name matches, but the signature doesn't, which means we have to
641 // search forward through the new overloaded methods.
642 int nj; // outside the loop for post-loop check
643 for (nj = ni + 1; nj < n_new_methods; nj++) {
644 methodOop m = (methodOop)k_new_methods->obj_at(nj);
645 if (k_old_method->name() != m->name()) {
646 // reached another method name so no more overloaded methods
647 method_was = deleted;
648 break;
649 }
650 if (k_old_method->signature() == m->signature()) {
651 // found a match so swap the methods
652 k_new_methods->obj_at_put(ni, m);
653 k_new_methods->obj_at_put(nj, k_new_method);
654 k_new_method = m;
655 method_was = matched;
656 break;
657 }
658 }
659
660 if (nj >= n_new_methods) {
661 // reached the end without a match; so method was deleted
662 method_was = deleted;
663 }
664 }
665 }
666
667 switch (method_was) {
668 case matched:
669 // methods match, be sure modifiers do too
670 old_flags = (jushort) k_old_method->access_flags().get_flags();
671 new_flags = (jushort) k_new_method->access_flags().get_flags();
672 if ((old_flags ^ new_flags) & ~(JVM_ACC_NATIVE)) {
673 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_METHOD_MODIFIERS_CHANGED;
674 }
675 {
676 u2 new_num = k_new_method->method_idnum();
677 u2 old_num = k_old_method->method_idnum();
678 if (new_num != old_num) {
679 methodOop idnum_owner = scratch_class->method_with_idnum(old_num);
680 if (idnum_owner != NULL) {
681 // There is already a method assigned this idnum -- switch them
682 idnum_owner->set_method_idnum(new_num);
683 }
684 k_new_method->set_method_idnum(old_num);
685 swap_all_method_annotations(old_num, new_num, scratch_class);
686 }
687 }
688 RC_TRACE(0x00008000, ("Method matched: new: %s [%d] == old: %s [%d]",
689 k_new_method->name_and_sig_as_C_string(), ni,
690 k_old_method->name_and_sig_as_C_string(), oi));
691 // advance to next pair of methods
692 ++oi;
693 ++ni;
694 break;
695 case added:
696 // method added, see if it is OK
697 new_flags = (jushort) k_new_method->access_flags().get_flags();
698 if ((new_flags & JVM_ACC_PRIVATE) == 0
699 // hack: private should be treated as final, but alas
700 || (new_flags & (JVM_ACC_FINAL|JVM_ACC_STATIC)) == 0
701 ) {
702 // new methods must be private
703 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_METHOD_ADDED;
704 }
705 {
706 u2 num = the_class->next_method_idnum();
707 if (num == constMethodOopDesc::UNSET_IDNUM) {
708 // cannot add any more methods
709 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_METHOD_ADDED;
710 }
711 u2 new_num = k_new_method->method_idnum();
712 methodOop idnum_owner = scratch_class->method_with_idnum(num);
713 if (idnum_owner != NULL) {
714 // There is already a method assigned this idnum -- switch them
715 idnum_owner->set_method_idnum(new_num);
716 }
717 k_new_method->set_method_idnum(num);
718 swap_all_method_annotations(new_num, num, scratch_class);
719 }
720 RC_TRACE(0x00008000, ("Method added: new: %s [%d]",
721 k_new_method->name_and_sig_as_C_string(), ni));
722 ++ni; // advance to next new method
723 break;
724 case deleted:
725 // method deleted, see if it is OK
726 old_flags = (jushort) k_old_method->access_flags().get_flags();
727 if ((old_flags & JVM_ACC_PRIVATE) == 0
728 // hack: private should be treated as final, but alas
729 || (old_flags & (JVM_ACC_FINAL|JVM_ACC_STATIC)) == 0
730 ) {
731 // deleted methods must be private
732 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_METHOD_DELETED;
733 }
734 RC_TRACE(0x00008000, ("Method deleted: old: %s [%d]",
735 k_old_method->name_and_sig_as_C_string(), oi));
736 ++oi; // advance to next old method
737 break;
738 default:
739 ShouldNotReachHere();
740 }
741 }
742
743 return JVMTI_ERROR_NONE;
744 }
745
746
747 // Find new constant pool index value for old constant pool index value
748 // by seaching the index map. Returns zero (0) if there is no mapped
749 // value for the old constant pool index.
750 int VM_RedefineClasses::find_new_index(int old_index) {
751 if (_index_map_count == 0) {
752 // map is empty so nothing can be found
753 return 0;
754 }
755
756 if (old_index < 1 || old_index >= _index_map_p->length()) {
757 // The old_index is out of range so it is not mapped. This should
758 // not happen in regular constant pool merging use, but it can
759 // happen if a corrupt annotation is processed.
760 return 0;
761 }
762
763 int value = _index_map_p->at(old_index);
764 if (value == -1) {
765 // the old_index is not mapped
766 return 0;
767 }
768
769 return value;
770 } // end find_new_index()
771
772
773 // Returns true if the current mismatch is due to a resolved/unresolved
774 // class pair. Otherwise, returns false.
775 bool VM_RedefineClasses::is_unresolved_class_mismatch(constantPoolHandle cp1,
776 int index1, constantPoolHandle cp2, int index2) {
777
778 jbyte t1 = cp1->tag_at(index1).value();
779 if (t1 != JVM_CONSTANT_Class && t1 != JVM_CONSTANT_UnresolvedClass) {
780 return false; // wrong entry type; not our special case
781 }
782
783 jbyte t2 = cp2->tag_at(index2).value();
784 if (t2 != JVM_CONSTANT_Class && t2 != JVM_CONSTANT_UnresolvedClass) {
785 return false; // wrong entry type; not our special case
786 }
787
788 if (t1 == t2) {
789 return false; // not a mismatch; not our special case
790 }
791
792 char *s1 = cp1->klass_name_at(index1)->as_C_string();
793 char *s2 = cp2->klass_name_at(index2)->as_C_string();
794 if (strcmp(s1, s2) != 0) {
795 return false; // strings don't match; not our special case
796 }
797
798 return true; // made it through the gauntlet; this is our special case
799 } // end is_unresolved_class_mismatch()
800
801
802 // Returns true if the current mismatch is due to a resolved/unresolved
803 // string pair. Otherwise, returns false.
804 bool VM_RedefineClasses::is_unresolved_string_mismatch(constantPoolHandle cp1,
805 int index1, constantPoolHandle cp2, int index2) {
806
807 jbyte t1 = cp1->tag_at(index1).value();
808 if (t1 != JVM_CONSTANT_String && t1 != JVM_CONSTANT_UnresolvedString) {
809 return false; // wrong entry type; not our special case
810 }
811
812 jbyte t2 = cp2->tag_at(index2).value();
813 if (t2 != JVM_CONSTANT_String && t2 != JVM_CONSTANT_UnresolvedString) {
814 return false; // wrong entry type; not our special case
815 }
816
817 if (t1 == t2) {
818 return false; // not a mismatch; not our special case
819 }
820
821 char *s1 = cp1->string_at_noresolve(index1);
822 char *s2 = cp2->string_at_noresolve(index2);
823 if (strcmp(s1, s2) != 0) {
824 return false; // strings don't match; not our special case
825 }
826
827 return true; // made it through the gauntlet; this is our special case
828 } // end is_unresolved_string_mismatch()
829
830
831 jvmtiError VM_RedefineClasses::load_new_class_versions(TRAPS) {
832 // For consistency allocate memory using os::malloc wrapper.
833 _scratch_classes = (instanceKlassHandle *)
834 os::malloc(sizeof(instanceKlassHandle) * _class_count);
835 if (_scratch_classes == NULL) {
836 return JVMTI_ERROR_OUT_OF_MEMORY;
837 }
838
839 ResourceMark rm(THREAD);
840
841 JvmtiThreadState *state = JvmtiThreadState::state_for(JavaThread::current());
842 // state can only be NULL if the current thread is exiting which
843 // should not happen since we're trying to do a RedefineClasses
844 guarantee(state != NULL, "exiting thread calling load_new_class_versions");
845 for (int i = 0; i < _class_count; i++) {
846 oop mirror = JNIHandles::resolve_non_null(_class_defs[i].klass);
847 // classes for primitives cannot be redefined
848 if (!is_modifiable_class(mirror)) {
849 return JVMTI_ERROR_UNMODIFIABLE_CLASS;
850 }
851 klassOop the_class_oop = java_lang_Class::as_klassOop(mirror);
852 instanceKlassHandle the_class = instanceKlassHandle(THREAD, the_class_oop);
853 Symbol* the_class_sym = the_class->name();
854
855 // RC_TRACE_WITH_THREAD macro has an embedded ResourceMark
856 RC_TRACE_WITH_THREAD(0x00000001, THREAD,
857 ("loading name=%s kind=%d (avail_mem=" UINT64_FORMAT "K)",
858 the_class->external_name(), _class_load_kind,
859 os::available_memory() >> 10));
860
861 ClassFileStream st((u1*) _class_defs[i].class_bytes,
862 _class_defs[i].class_byte_count, (char *)"__VM_RedefineClasses__");
863
864 // Parse the stream.
865 Handle the_class_loader(THREAD, the_class->class_loader());
866 Handle protection_domain(THREAD, the_class->protection_domain());
867 // Set redefined class handle in JvmtiThreadState class.
868 // This redefined class is sent to agent event handler for class file
869 // load hook event.
870 state->set_class_being_redefined(&the_class, _class_load_kind);
871
872 klassOop k = SystemDictionary::parse_stream(the_class_sym,
873 the_class_loader,
874 protection_domain,
875 &st,
876 THREAD);
877 // Clear class_being_redefined just to be sure.
878 state->clear_class_being_redefined();
879
880 // TODO: if this is retransform, and nothing changed we can skip it
881
882 instanceKlassHandle scratch_class (THREAD, k);
883
884 if (HAS_PENDING_EXCEPTION) {
885 Symbol* ex_name = PENDING_EXCEPTION->klass()->klass_part()->name();
886 // RC_TRACE_WITH_THREAD macro has an embedded ResourceMark
887 RC_TRACE_WITH_THREAD(0x00000002, THREAD, ("parse_stream exception: '%s'",
888 ex_name->as_C_string()));
889 CLEAR_PENDING_EXCEPTION;
890
891 if (ex_name == vmSymbols::java_lang_UnsupportedClassVersionError()) {
892 return JVMTI_ERROR_UNSUPPORTED_VERSION;
893 } else if (ex_name == vmSymbols::java_lang_ClassFormatError()) {
894 return JVMTI_ERROR_INVALID_CLASS_FORMAT;
895 } else if (ex_name == vmSymbols::java_lang_ClassCircularityError()) {
896 return JVMTI_ERROR_CIRCULAR_CLASS_DEFINITION;
897 } else if (ex_name == vmSymbols::java_lang_NoClassDefFoundError()) {
898 // The message will be "XXX (wrong name: YYY)"
899 return JVMTI_ERROR_NAMES_DONT_MATCH;
900 } else if (ex_name == vmSymbols::java_lang_OutOfMemoryError()) {
901 return JVMTI_ERROR_OUT_OF_MEMORY;
902 } else { // Just in case more exceptions can be thrown..
903 return JVMTI_ERROR_FAILS_VERIFICATION;
904 }
905 }
906
907 // Ensure class is linked before redefine
908 if (!the_class->is_linked()) {
909 the_class->link_class(THREAD);
910 if (HAS_PENDING_EXCEPTION) {
911 Symbol* ex_name = PENDING_EXCEPTION->klass()->klass_part()->name();
912 // RC_TRACE_WITH_THREAD macro has an embedded ResourceMark
913 RC_TRACE_WITH_THREAD(0x00000002, THREAD, ("link_class exception: '%s'",
914 ex_name->as_C_string()));
915 CLEAR_PENDING_EXCEPTION;
916 if (ex_name == vmSymbols::java_lang_OutOfMemoryError()) {
917 return JVMTI_ERROR_OUT_OF_MEMORY;
918 } else {
919 return JVMTI_ERROR_INTERNAL;
920 }
921 }
922 }
923
924 // Do the validity checks in compare_and_normalize_class_versions()
925 // before verifying the byte codes. By doing these checks first, we
926 // limit the number of functions that require redirection from
927 // the_class to scratch_class. In particular, we don't have to
928 // modify JNI GetSuperclass() and thus won't change its performance.
929 jvmtiError res = compare_and_normalize_class_versions(the_class,
930 scratch_class);
931 if (res != JVMTI_ERROR_NONE) {
932 return res;
933 }
934
935 // verify what the caller passed us
936 {
937 // The bug 6214132 caused the verification to fail.
938 // Information about the_class and scratch_class is temporarily
939 // recorded into jvmtiThreadState. This data is used to redirect
940 // the_class to scratch_class in the JVM_* functions called by the
941 // verifier. Please, refer to jvmtiThreadState.hpp for the detailed
942 // description.
943 RedefineVerifyMark rvm(&the_class, &scratch_class, state);
944 Verifier::verify(
945 scratch_class, Verifier::ThrowException, true, THREAD);
946 }
947
948 if (HAS_PENDING_EXCEPTION) {
949 Symbol* ex_name = PENDING_EXCEPTION->klass()->klass_part()->name();
950 // RC_TRACE_WITH_THREAD macro has an embedded ResourceMark
951 RC_TRACE_WITH_THREAD(0x00000002, THREAD,
952 ("verify_byte_codes exception: '%s'", ex_name->as_C_string()));
953 CLEAR_PENDING_EXCEPTION;
954 if (ex_name == vmSymbols::java_lang_OutOfMemoryError()) {
955 return JVMTI_ERROR_OUT_OF_MEMORY;
956 } else {
957 // tell the caller the bytecodes are bad
958 return JVMTI_ERROR_FAILS_VERIFICATION;
959 }
960 }
961
962 res = merge_cp_and_rewrite(the_class, scratch_class, THREAD);
963 if (res != JVMTI_ERROR_NONE) {
964 return res;
965 }
966
967 if (VerifyMergedCPBytecodes) {
968 // verify what we have done during constant pool merging
969 {
970 RedefineVerifyMark rvm(&the_class, &scratch_class, state);
971 Verifier::verify(scratch_class, Verifier::ThrowException, true, THREAD);
972 }
973
974 if (HAS_PENDING_EXCEPTION) {
975 Symbol* ex_name = PENDING_EXCEPTION->klass()->klass_part()->name();
976 // RC_TRACE_WITH_THREAD macro has an embedded ResourceMark
977 RC_TRACE_WITH_THREAD(0x00000002, THREAD,
978 ("verify_byte_codes post merge-CP exception: '%s'",
979 ex_name->as_C_string()));
980 CLEAR_PENDING_EXCEPTION;
981 if (ex_name == vmSymbols::java_lang_OutOfMemoryError()) {
982 return JVMTI_ERROR_OUT_OF_MEMORY;
983 } else {
984 // tell the caller that constant pool merging screwed up
985 return JVMTI_ERROR_INTERNAL;
986 }
987 }
988 }
989
990 Rewriter::rewrite(scratch_class, THREAD);
991 if (!HAS_PENDING_EXCEPTION) {
992 Rewriter::relocate_and_link(scratch_class, THREAD);
993 }
994 if (HAS_PENDING_EXCEPTION) {
995 Symbol* ex_name = PENDING_EXCEPTION->klass()->klass_part()->name();
996 CLEAR_PENDING_EXCEPTION;
997 if (ex_name == vmSymbols::java_lang_OutOfMemoryError()) {
998 return JVMTI_ERROR_OUT_OF_MEMORY;
999 } else {
1000 return JVMTI_ERROR_INTERNAL;
1001 }
1002 }
1003
1004 _scratch_classes[i] = scratch_class;
1005
1006 // RC_TRACE_WITH_THREAD macro has an embedded ResourceMark
1007 RC_TRACE_WITH_THREAD(0x00000001, THREAD,
1008 ("loaded name=%s (avail_mem=" UINT64_FORMAT "K)",
1009 the_class->external_name(), os::available_memory() >> 10));
1010 }
1011
1012 return JVMTI_ERROR_NONE;
1013 }
1014
1015
1016 // Map old_index to new_index as needed. scratch_cp is only needed
1017 // for RC_TRACE() calls.
1018 void VM_RedefineClasses::map_index(constantPoolHandle scratch_cp,
1019 int old_index, int new_index) {
1020 if (find_new_index(old_index) != 0) {
1021 // old_index is already mapped
1022 return;
1023 }
1024
1025 if (old_index == new_index) {
1026 // no mapping is needed
1027 return;
1028 }
1029
1030 _index_map_p->at_put(old_index, new_index);
1031 _index_map_count++;
1032
1033 RC_TRACE(0x00040000, ("mapped tag %d at index %d to %d",
1034 scratch_cp->tag_at(old_index).value(), old_index, new_index));
1035 } // end map_index()
1036
1037
1038 // Merge old_cp and scratch_cp and return the results of the merge via
1039 // merge_cp_p. The number of entries in *merge_cp_p is returned via
1040 // merge_cp_length_p. The entries in old_cp occupy the same locations
1041 // in *merge_cp_p. Also creates a map of indices from entries in
1042 // scratch_cp to the corresponding entry in *merge_cp_p. Index map
1043 // entries are only created for entries in scratch_cp that occupy a
1044 // different location in *merged_cp_p.
1045 bool VM_RedefineClasses::merge_constant_pools(constantPoolHandle old_cp,
1046 constantPoolHandle scratch_cp, constantPoolHandle *merge_cp_p,
1047 int *merge_cp_length_p, TRAPS) {
1048
1049 if (merge_cp_p == NULL) {
1050 assert(false, "caller must provide scatch constantPool");
1051 return false; // robustness
1052 }
1053 if (merge_cp_length_p == NULL) {
1054 assert(false, "caller must provide scatch CP length");
1055 return false; // robustness
1056 }
1057 // Worst case we need old_cp->length() + scratch_cp()->length(),
1058 // but the caller might be smart so make sure we have at least
1059 // the minimum.
1060 if ((*merge_cp_p)->length() < old_cp->length()) {
1061 assert(false, "merge area too small");
1062 return false; // robustness
1063 }
1064
1065 RC_TRACE_WITH_THREAD(0x00010000, THREAD,
1066 ("old_cp_len=%d, scratch_cp_len=%d", old_cp->length(),
1067 scratch_cp->length()));
1068
1069 {
1070 // Pass 0:
1071 // The old_cp is copied to *merge_cp_p; this means that any code
1072 // using old_cp does not have to change. This work looks like a
1073 // perfect fit for constantPoolOop::copy_cp_to(), but we need to
1074 // handle one special case:
1075 // - revert JVM_CONSTANT_Class to JVM_CONSTANT_UnresolvedClass
1076 // This will make verification happy.
1077
1078 int old_i; // index into old_cp
1079
1080 // index zero (0) is not used in constantPools
1081 for (old_i = 1; old_i < old_cp->length(); old_i++) {
1082 // leave debugging crumb
1083 jbyte old_tag = old_cp->tag_at(old_i).value();
1084 switch (old_tag) {
1085 case JVM_CONSTANT_Class:
1086 case JVM_CONSTANT_UnresolvedClass:
1087 // revert the copy to JVM_CONSTANT_UnresolvedClass
1088 // May be resolving while calling this so do the same for
1089 // JVM_CONSTANT_UnresolvedClass (klass_name_at() deals with transition)
1090 (*merge_cp_p)->unresolved_klass_at_put(old_i,
1091 old_cp->klass_name_at(old_i));
1092 break;
1093
1094 case JVM_CONSTANT_Double:
1095 case JVM_CONSTANT_Long:
1096 // just copy the entry to *merge_cp_p, but double and long take
1097 // two constant pool entries
1098 constantPoolOopDesc::copy_entry_to(old_cp, old_i, *merge_cp_p, old_i, CHECK_0);
1099 old_i++;
1100 break;
1101
1102 default:
1103 // just copy the entry to *merge_cp_p
1104 constantPoolOopDesc::copy_entry_to(old_cp, old_i, *merge_cp_p, old_i, CHECK_0);
1105 break;
1106 }
1107 } // end for each old_cp entry
1108
1109 // We don't need to sanity check that *merge_cp_length_p is within
1110 // *merge_cp_p bounds since we have the minimum on-entry check above.
1111 (*merge_cp_length_p) = old_i;
1112 }
1113
1114 // merge_cp_len should be the same as old_cp->length() at this point
1115 // so this trace message is really a "warm-and-breathing" message.
1116 RC_TRACE_WITH_THREAD(0x00020000, THREAD,
1117 ("after pass 0: merge_cp_len=%d", *merge_cp_length_p));
1118
1119 int scratch_i; // index into scratch_cp
1120 {
1121 // Pass 1a:
1122 // Compare scratch_cp entries to the old_cp entries that we have
1123 // already copied to *merge_cp_p. In this pass, we are eliminating
1124 // exact duplicates (matching entry at same index) so we only
1125 // compare entries in the common indice range.
1126 int increment = 1;
1127 int pass1a_length = MIN2(old_cp->length(), scratch_cp->length());
1128 for (scratch_i = 1; scratch_i < pass1a_length; scratch_i += increment) {
1129 switch (scratch_cp->tag_at(scratch_i).value()) {
1130 case JVM_CONSTANT_Double:
1131 case JVM_CONSTANT_Long:
1132 // double and long take two constant pool entries
1133 increment = 2;
1134 break;
1135
1136 default:
1137 increment = 1;
1138 break;
1139 }
1140
1141 bool match = scratch_cp->compare_entry_to(scratch_i, *merge_cp_p,
1142 scratch_i, CHECK_0);
1143 if (match) {
1144 // found a match at the same index so nothing more to do
1145 continue;
1146 } else if (is_unresolved_class_mismatch(scratch_cp, scratch_i,
1147 *merge_cp_p, scratch_i)) {
1148 // The mismatch in compare_entry_to() above is because of a
1149 // resolved versus unresolved class entry at the same index
1150 // with the same string value. Since Pass 0 reverted any
1151 // class entries to unresolved class entries in *merge_cp_p,
1152 // we go with the unresolved class entry.
1153 continue;
1154 } else if (is_unresolved_string_mismatch(scratch_cp, scratch_i,
1155 *merge_cp_p, scratch_i)) {
1156 // The mismatch in compare_entry_to() above is because of a
1157 // resolved versus unresolved string entry at the same index
1158 // with the same string value. We can live with whichever
1159 // happens to be at scratch_i in *merge_cp_p.
1160 continue;
1161 }
1162
1163 int found_i = scratch_cp->find_matching_entry(scratch_i, *merge_cp_p,
1164 CHECK_0);
1165 if (found_i != 0) {
1166 guarantee(found_i != scratch_i,
1167 "compare_entry_to() and find_matching_entry() do not agree");
1168
1169 // Found a matching entry somewhere else in *merge_cp_p so
1170 // just need a mapping entry.
1171 map_index(scratch_cp, scratch_i, found_i);
1172 continue;
1173 }
1174
1175 // The find_matching_entry() call above could fail to find a match
1176 // due to a resolved versus unresolved class or string entry situation
1177 // like we solved above with the is_unresolved_*_mismatch() calls.
1178 // However, we would have to call is_unresolved_*_mismatch() over
1179 // all of *merge_cp_p (potentially) and that doesn't seem to be
1180 // worth the time.
1181
1182 // No match found so we have to append this entry and any unique
1183 // referenced entries to *merge_cp_p.
1184 append_entry(scratch_cp, scratch_i, merge_cp_p, merge_cp_length_p,
1185 CHECK_0);
1186 }
1187 }
1188
1189 RC_TRACE_WITH_THREAD(0x00020000, THREAD,
1190 ("after pass 1a: merge_cp_len=%d, scratch_i=%d, index_map_len=%d",
1191 *merge_cp_length_p, scratch_i, _index_map_count));
1192
1193 if (scratch_i < scratch_cp->length()) {
1194 // Pass 1b:
1195 // old_cp is smaller than scratch_cp so there are entries in
1196 // scratch_cp that we have not yet processed. We take care of
1197 // those now.
1198 int increment = 1;
1199 for (; scratch_i < scratch_cp->length(); scratch_i += increment) {
1200 switch (scratch_cp->tag_at(scratch_i).value()) {
1201 case JVM_CONSTANT_Double:
1202 case JVM_CONSTANT_Long:
1203 // double and long take two constant pool entries
1204 increment = 2;
1205 break;
1206
1207 default:
1208 increment = 1;
1209 break;
1210 }
1211
1212 int found_i =
1213 scratch_cp->find_matching_entry(scratch_i, *merge_cp_p, CHECK_0);
1214 if (found_i != 0) {
1215 // Found a matching entry somewhere else in *merge_cp_p so
1216 // just need a mapping entry.
1217 map_index(scratch_cp, scratch_i, found_i);
1218 continue;
1219 }
1220
1221 // No match found so we have to append this entry and any unique
1222 // referenced entries to *merge_cp_p.
1223 append_entry(scratch_cp, scratch_i, merge_cp_p, merge_cp_length_p,
1224 CHECK_0);
1225 }
1226
1227 RC_TRACE_WITH_THREAD(0x00020000, THREAD,
1228 ("after pass 1b: merge_cp_len=%d, scratch_i=%d, index_map_len=%d",
1229 *merge_cp_length_p, scratch_i, _index_map_count));
1230 }
1231
1232 return true;
1233 } // end merge_constant_pools()
1234
1235
1236 // Merge constant pools between the_class and scratch_class and
1237 // potentially rewrite bytecodes in scratch_class to use the merged
1238 // constant pool.
1239 jvmtiError VM_RedefineClasses::merge_cp_and_rewrite(
1240 instanceKlassHandle the_class, instanceKlassHandle scratch_class,
1241 TRAPS) {
1242 // worst case merged constant pool length is old and new combined
1243 int merge_cp_length = the_class->constants()->length()
1244 + scratch_class->constants()->length();
1245
1246 constantPoolHandle old_cp(THREAD, the_class->constants());
1247 constantPoolHandle scratch_cp(THREAD, scratch_class->constants());
1248
1249 // Constant pools are not easily reused so we allocate a new one
1250 // each time.
1251 // merge_cp is created unsafe for concurrent GC processing. It
1252 // should be marked safe before discarding it. Even though
1253 // garbage, if it crosses a card boundary, it may be scanned
1254 // in order to find the start of the first complete object on the card.
1255 constantPoolHandle merge_cp(THREAD,
1256 oopFactory::new_constantPool(merge_cp_length,
1257 oopDesc::IsUnsafeConc,
1258 THREAD));
1259 int orig_length = old_cp->orig_length();
1260 if (orig_length == 0) {
1261 // This old_cp is an actual original constant pool. We save
1262 // the original length in the merged constant pool so that
1263 // merge_constant_pools() can be more efficient. If a constant
1264 // pool has a non-zero orig_length() value, then that constant
1265 // pool was created by a merge operation in RedefineClasses.
1266 merge_cp->set_orig_length(old_cp->length());
1267 } else {
1268 // This old_cp is a merged constant pool from a previous
1269 // RedefineClasses() calls so just copy the orig_length()
1270 // value.
1271 merge_cp->set_orig_length(old_cp->orig_length());
1272 }
1273
1274 ResourceMark rm(THREAD);
1275 _index_map_count = 0;
1276 _index_map_p = new intArray(scratch_cp->length(), -1);
1277
1278 bool result = merge_constant_pools(old_cp, scratch_cp, &merge_cp,
1279 &merge_cp_length, THREAD);
1280 if (!result) {
1281 // The merge can fail due to memory allocation failure or due
1282 // to robustness checks.
1283 return JVMTI_ERROR_INTERNAL;
1284 }
1285
1286 RC_TRACE_WITH_THREAD(0x00010000, THREAD,
1287 ("merge_cp_len=%d, index_map_len=%d", merge_cp_length, _index_map_count));
1288
1289 if (_index_map_count == 0) {
1290 // there is nothing to map between the new and merged constant pools
1291
1292 if (old_cp->length() == scratch_cp->length()) {
1293 // The old and new constant pools are the same length and the
1294 // index map is empty. This means that the three constant pools
1295 // are equivalent (but not the same). Unfortunately, the new
1296 // constant pool has not gone through link resolution nor have
1297 // the new class bytecodes gone through constant pool cache
1298 // rewriting so we can't use the old constant pool with the new
1299 // class.
1300
1301 merge_cp()->set_is_conc_safe(true);
1302 merge_cp = constantPoolHandle(); // toss the merged constant pool
1303 } else if (old_cp->length() < scratch_cp->length()) {
1304 // The old constant pool has fewer entries than the new constant
1305 // pool and the index map is empty. This means the new constant
1306 // pool is a superset of the old constant pool. However, the old
1307 // class bytecodes have already gone through constant pool cache
1308 // rewriting so we can't use the new constant pool with the old
1309 // class.
1310
1311 merge_cp()->set_is_conc_safe(true);
1312 merge_cp = constantPoolHandle(); // toss the merged constant pool
1313 } else {
1314 // The old constant pool has more entries than the new constant
1315 // pool and the index map is empty. This means that both the old
1316 // and merged constant pools are supersets of the new constant
1317 // pool.
1318
1319 // Replace the new constant pool with a shrunken copy of the
1320 // merged constant pool; the previous new constant pool will
1321 // get GCed.
1322 set_new_constant_pool(scratch_class, merge_cp, merge_cp_length, true,
1323 THREAD);
1324 // drop local ref to the merged constant pool
1325 merge_cp()->set_is_conc_safe(true);
1326 merge_cp = constantPoolHandle();
1327 }
1328 } else {
1329 if (RC_TRACE_ENABLED(0x00040000)) {
1330 // don't want to loop unless we are tracing
1331 int count = 0;
1332 for (int i = 1; i < _index_map_p->length(); i++) {
1333 int value = _index_map_p->at(i);
1334
1335 if (value != -1) {
1336 RC_TRACE_WITH_THREAD(0x00040000, THREAD,
1337 ("index_map[%d]: old=%d new=%d", count, i, value));
1338 count++;
1339 }
1340 }
1341 }
1342
1343 // We have entries mapped between the new and merged constant pools
1344 // so we have to rewrite some constant pool references.
1345 if (!rewrite_cp_refs(scratch_class, THREAD)) {
1346 return JVMTI_ERROR_INTERNAL;
1347 }
1348
1349 // Replace the new constant pool with a shrunken copy of the
1350 // merged constant pool so now the rewritten bytecodes have
1351 // valid references; the previous new constant pool will get
1352 // GCed.
1353 set_new_constant_pool(scratch_class, merge_cp, merge_cp_length, true,
1354 THREAD);
1355 merge_cp()->set_is_conc_safe(true);
1356 }
1357 assert(old_cp()->is_conc_safe(), "Just checking");
1358 assert(scratch_cp()->is_conc_safe(), "Just checking");
1359
1360 return JVMTI_ERROR_NONE;
1361 } // end merge_cp_and_rewrite()
1362
1363
1364 // Rewrite constant pool references in klass scratch_class.
1365 bool VM_RedefineClasses::rewrite_cp_refs(instanceKlassHandle scratch_class,
1366 TRAPS) {
1367
1368 // rewrite constant pool references in the methods:
1369 if (!rewrite_cp_refs_in_methods(scratch_class, THREAD)) {
1370 // propagate failure back to caller
1371 return false;
1372 }
1373
1374 // rewrite constant pool references in the class_annotations:
1375 if (!rewrite_cp_refs_in_class_annotations(scratch_class, THREAD)) {
1376 // propagate failure back to caller
1377 return false;
1378 }
1379
1380 // rewrite constant pool references in the fields_annotations:
1381 if (!rewrite_cp_refs_in_fields_annotations(scratch_class, THREAD)) {
1382 // propagate failure back to caller
1383 return false;
1384 }
1385
1386 // rewrite constant pool references in the methods_annotations:
1387 if (!rewrite_cp_refs_in_methods_annotations(scratch_class, THREAD)) {
1388 // propagate failure back to caller
1389 return false;
1390 }
1391
1392 // rewrite constant pool references in the methods_parameter_annotations:
1393 if (!rewrite_cp_refs_in_methods_parameter_annotations(scratch_class,
1394 THREAD)) {
1395 // propagate failure back to caller
1396 return false;
1397 }
1398
1399 // rewrite constant pool references in the methods_default_annotations:
1400 if (!rewrite_cp_refs_in_methods_default_annotations(scratch_class,
1401 THREAD)) {
1402 // propagate failure back to caller
1403 return false;
1404 }
1405
1406 return true;
1407 } // end rewrite_cp_refs()
1408
1409
1410 // Rewrite constant pool references in the methods.
1411 bool VM_RedefineClasses::rewrite_cp_refs_in_methods(
1412 instanceKlassHandle scratch_class, TRAPS) {
1413
1414 objArrayHandle methods(THREAD, scratch_class->methods());
1415
1416 if (methods.is_null() || methods->length() == 0) {
1417 // no methods so nothing to do
1418 return true;
1419 }
1420
1421 // rewrite constant pool references in the methods:
1422 for (int i = methods->length() - 1; i >= 0; i--) {
1423 methodHandle method(THREAD, (methodOop)methods->obj_at(i));
1424 methodHandle new_method;
1425 rewrite_cp_refs_in_method(method, &new_method, CHECK_false);
1426 if (!new_method.is_null()) {
1427 // the method has been replaced so save the new method version
1428 methods->obj_at_put(i, new_method());
1429 }
1430 }
1431
1432 return true;
1433 }
1434
1435
1436 // Rewrite constant pool references in the specific method. This code
1437 // was adapted from Rewriter::rewrite_method().
1438 void VM_RedefineClasses::rewrite_cp_refs_in_method(methodHandle method,
1439 methodHandle *new_method_p, TRAPS) {
1440
1441 *new_method_p = methodHandle(); // default is no new method
1442
1443 // We cache a pointer to the bytecodes here in code_base. If GC
1444 // moves the methodOop, then the bytecodes will also move which
1445 // will likely cause a crash. We create a No_Safepoint_Verifier
1446 // object to detect whether we pass a possible safepoint in this
1447 // code block.
1448 No_Safepoint_Verifier nsv;
1449
1450 // Bytecodes and their length
1451 address code_base = method->code_base();
1452 int code_length = method->code_size();
1453
1454 int bc_length;
1455 for (int bci = 0; bci < code_length; bci += bc_length) {
1456 address bcp = code_base + bci;
1457 Bytecodes::Code c = (Bytecodes::Code)(*bcp);
1458
1459 bc_length = Bytecodes::length_for(c);
1460 if (bc_length == 0) {
1461 // More complicated bytecodes report a length of zero so
1462 // we have to try again a slightly different way.
1463 bc_length = Bytecodes::length_at(method(), bcp);
1464 }
1465
1466 assert(bc_length != 0, "impossible bytecode length");
1467
1468 switch (c) {
1469 case Bytecodes::_ldc:
1470 {
1471 int cp_index = *(bcp + 1);
1472 int new_index = find_new_index(cp_index);
1473
1474 if (StressLdcRewrite && new_index == 0) {
1475 // If we are stressing ldc -> ldc_w rewriting, then we
1476 // always need a new_index value.
1477 new_index = cp_index;
1478 }
1479 if (new_index != 0) {
1480 // the original index is mapped so we have more work to do
1481 if (!StressLdcRewrite && new_index <= max_jubyte) {
1482 // The new value can still use ldc instead of ldc_w
1483 // unless we are trying to stress ldc -> ldc_w rewriting
1484 RC_TRACE_WITH_THREAD(0x00080000, THREAD,
1485 ("%s@" INTPTR_FORMAT " old=%d, new=%d", Bytecodes::name(c),
1486 bcp, cp_index, new_index));
1487 *(bcp + 1) = new_index;
1488 } else {
1489 RC_TRACE_WITH_THREAD(0x00080000, THREAD,
1490 ("%s->ldc_w@" INTPTR_FORMAT " old=%d, new=%d",
1491 Bytecodes::name(c), bcp, cp_index, new_index));
1492 // the new value needs ldc_w instead of ldc
1493 u_char inst_buffer[4]; // max instruction size is 4 bytes
1494 bcp = (address)inst_buffer;
1495 // construct new instruction sequence
1496 *bcp = Bytecodes::_ldc_w;
1497 bcp++;
1498 // Rewriter::rewrite_method() does not rewrite ldc -> ldc_w.
1499 // See comment below for difference between put_Java_u2()
1500 // and put_native_u2().
1501 Bytes::put_Java_u2(bcp, new_index);
1502
1503 Relocator rc(method, NULL /* no RelocatorListener needed */);
1504 methodHandle m;
1505 {
1506 Pause_No_Safepoint_Verifier pnsv(&nsv);
1507
1508 // ldc is 2 bytes and ldc_w is 3 bytes
1509 m = rc.insert_space_at(bci, 3, inst_buffer, THREAD);
1510 if (m.is_null() || HAS_PENDING_EXCEPTION) {
1511 guarantee(false, "insert_space_at() failed");
1512 }
1513 }
1514
1515 // return the new method so that the caller can update
1516 // the containing class
1517 *new_method_p = method = m;
1518 // switch our bytecode processing loop from the old method
1519 // to the new method
1520 code_base = method->code_base();
1521 code_length = method->code_size();
1522 bcp = code_base + bci;
1523 c = (Bytecodes::Code)(*bcp);
1524 bc_length = Bytecodes::length_for(c);
1525 assert(bc_length != 0, "sanity check");
1526 } // end we need ldc_w instead of ldc
1527 } // end if there is a mapped index
1528 } break;
1529
1530 // these bytecodes have a two-byte constant pool index
1531 case Bytecodes::_anewarray : // fall through
1532 case Bytecodes::_checkcast : // fall through
1533 case Bytecodes::_getfield : // fall through
1534 case Bytecodes::_getstatic : // fall through
1535 case Bytecodes::_instanceof : // fall through
1536 case Bytecodes::_invokeinterface: // fall through
1537 case Bytecodes::_invokespecial : // fall through
1538 case Bytecodes::_invokestatic : // fall through
1539 case Bytecodes::_invokevirtual : // fall through
1540 case Bytecodes::_ldc_w : // fall through
1541 case Bytecodes::_ldc2_w : // fall through
1542 case Bytecodes::_multianewarray : // fall through
1543 case Bytecodes::_new : // fall through
1544 case Bytecodes::_putfield : // fall through
1545 case Bytecodes::_putstatic :
1546 {
1547 address p = bcp + 1;
1548 int cp_index = Bytes::get_Java_u2(p);
1549 int new_index = find_new_index(cp_index);
1550 if (new_index != 0) {
1551 // the original index is mapped so update w/ new value
1552 RC_TRACE_WITH_THREAD(0x00080000, THREAD,
1553 ("%s@" INTPTR_FORMAT " old=%d, new=%d", Bytecodes::name(c),
1554 bcp, cp_index, new_index));
1555 // Rewriter::rewrite_method() uses put_native_u2() in this
1556 // situation because it is reusing the constant pool index
1557 // location for a native index into the constantPoolCache.
1558 // Since we are updating the constant pool index prior to
1559 // verification and constantPoolCache initialization, we
1560 // need to keep the new index in Java byte order.
1561 Bytes::put_Java_u2(p, new_index);
1562 }
1563 } break;
1564 }
1565 } // end for each bytecode
1566 } // end rewrite_cp_refs_in_method()
1567
1568
1569 // Rewrite constant pool references in the class_annotations field.
1570 bool VM_RedefineClasses::rewrite_cp_refs_in_class_annotations(
1571 instanceKlassHandle scratch_class, TRAPS) {
1572
1573 typeArrayHandle class_annotations(THREAD,
1574 scratch_class->class_annotations());
1575 if (class_annotations.is_null() || class_annotations->length() == 0) {
1576 // no class_annotations so nothing to do
1577 return true;
1578 }
1579
1580 RC_TRACE_WITH_THREAD(0x02000000, THREAD,
1581 ("class_annotations length=%d", class_annotations->length()));
1582
1583 int byte_i = 0; // byte index into class_annotations
1584 return rewrite_cp_refs_in_annotations_typeArray(class_annotations, byte_i,
1585 THREAD);
1586 }
1587
1588
1589 // Rewrite constant pool references in an annotations typeArray. This
1590 // "structure" is adapted from the RuntimeVisibleAnnotations_attribute
1591 // that is described in section 4.8.15 of the 2nd-edition of the VM spec:
1592 //
1593 // annotations_typeArray {
1594 // u2 num_annotations;
1595 // annotation annotations[num_annotations];
1596 // }
1597 //
1598 bool VM_RedefineClasses::rewrite_cp_refs_in_annotations_typeArray(
1599 typeArrayHandle annotations_typeArray, int &byte_i_ref, TRAPS) {
1600
1601 if ((byte_i_ref + 2) > annotations_typeArray->length()) {
1602 // not enough room for num_annotations field
1603 RC_TRACE_WITH_THREAD(0x02000000, THREAD,
1604 ("length() is too small for num_annotations field"));
1605 return false;
1606 }
1607
1608 u2 num_annotations = Bytes::get_Java_u2((address)
1609 annotations_typeArray->byte_at_addr(byte_i_ref));
1610 byte_i_ref += 2;
1611
1612 RC_TRACE_WITH_THREAD(0x02000000, THREAD,
1613 ("num_annotations=%d", num_annotations));
1614
1615 int calc_num_annotations = 0;
1616 for (; calc_num_annotations < num_annotations; calc_num_annotations++) {
1617 if (!rewrite_cp_refs_in_annotation_struct(annotations_typeArray,
1618 byte_i_ref, THREAD)) {
1619 RC_TRACE_WITH_THREAD(0x02000000, THREAD,
1620 ("bad annotation_struct at %d", calc_num_annotations));
1621 // propagate failure back to caller
1622 return false;
1623 }
1624 }
1625 assert(num_annotations == calc_num_annotations, "sanity check");
1626
1627 return true;
1628 } // end rewrite_cp_refs_in_annotations_typeArray()
1629
1630
1631 // Rewrite constant pool references in the annotation struct portion of
1632 // an annotations_typeArray. This "structure" is from section 4.8.15 of
1633 // the 2nd-edition of the VM spec:
1634 //
1635 // struct annotation {
1636 // u2 type_index;
1637 // u2 num_element_value_pairs;
1638 // {
1639 // u2 element_name_index;
1640 // element_value value;
1641 // } element_value_pairs[num_element_value_pairs];
1642 // }
1643 //
1644 bool VM_RedefineClasses::rewrite_cp_refs_in_annotation_struct(
1645 typeArrayHandle annotations_typeArray, int &byte_i_ref, TRAPS) {
1646 if ((byte_i_ref + 2 + 2) > annotations_typeArray->length()) {
1647 // not enough room for smallest annotation_struct
1648 RC_TRACE_WITH_THREAD(0x02000000, THREAD,
1649 ("length() is too small for annotation_struct"));
1650 return false;
1651 }
1652
1653 u2 type_index = rewrite_cp_ref_in_annotation_data(annotations_typeArray,
1654 byte_i_ref, "mapped old type_index=%d", THREAD);
1655
1656 u2 num_element_value_pairs = Bytes::get_Java_u2((address)
1657 annotations_typeArray->byte_at_addr(
1658 byte_i_ref));
1659 byte_i_ref += 2;
1660
1661 RC_TRACE_WITH_THREAD(0x02000000, THREAD,
1662 ("type_index=%d num_element_value_pairs=%d", type_index,
1663 num_element_value_pairs));
1664
1665 int calc_num_element_value_pairs = 0;
1666 for (; calc_num_element_value_pairs < num_element_value_pairs;
1667 calc_num_element_value_pairs++) {
1668 if ((byte_i_ref + 2) > annotations_typeArray->length()) {
1669 // not enough room for another element_name_index, let alone
1670 // the rest of another component
1671 RC_TRACE_WITH_THREAD(0x02000000, THREAD,
1672 ("length() is too small for element_name_index"));
1673 return false;
1674 }
1675
1676 u2 element_name_index = rewrite_cp_ref_in_annotation_data(
1677 annotations_typeArray, byte_i_ref,
1678 "mapped old element_name_index=%d", THREAD);
1679
1680 RC_TRACE_WITH_THREAD(0x02000000, THREAD,
1681 ("element_name_index=%d", element_name_index));
1682
1683 if (!rewrite_cp_refs_in_element_value(annotations_typeArray,
1684 byte_i_ref, THREAD)) {
1685 RC_TRACE_WITH_THREAD(0x02000000, THREAD,
1686 ("bad element_value at %d", calc_num_element_value_pairs));
1687 // propagate failure back to caller
1688 return false;
1689 }
1690 } // end for each component
1691 assert(num_element_value_pairs == calc_num_element_value_pairs,
1692 "sanity check");
1693
1694 return true;
1695 } // end rewrite_cp_refs_in_annotation_struct()
1696
1697
1698 // Rewrite a constant pool reference at the current position in
1699 // annotations_typeArray if needed. Returns the original constant
1700 // pool reference if a rewrite was not needed or the new constant
1701 // pool reference if a rewrite was needed.
1702 u2 VM_RedefineClasses::rewrite_cp_ref_in_annotation_data(
1703 typeArrayHandle annotations_typeArray, int &byte_i_ref,
1704 const char * trace_mesg, TRAPS) {
1705
1706 address cp_index_addr = (address)
1707 annotations_typeArray->byte_at_addr(byte_i_ref);
1708 u2 old_cp_index = Bytes::get_Java_u2(cp_index_addr);
1709 u2 new_cp_index = find_new_index(old_cp_index);
1710 if (new_cp_index != 0) {
1711 RC_TRACE_WITH_THREAD(0x02000000, THREAD, (trace_mesg, old_cp_index));
1712 Bytes::put_Java_u2(cp_index_addr, new_cp_index);
1713 old_cp_index = new_cp_index;
1714 }
1715 byte_i_ref += 2;
1716 return old_cp_index;
1717 }
1718
1719
1720 // Rewrite constant pool references in the element_value portion of an
1721 // annotations_typeArray. This "structure" is from section 4.8.15.1 of
1722 // the 2nd-edition of the VM spec:
1723 //
1724 // struct element_value {
1725 // u1 tag;
1726 // union {
1727 // u2 const_value_index;
1728 // {
1729 // u2 type_name_index;
1730 // u2 const_name_index;
1731 // } enum_const_value;
1732 // u2 class_info_index;
1733 // annotation annotation_value;
1734 // struct {
1735 // u2 num_values;
1736 // element_value values[num_values];
1737 // } array_value;
1738 // } value;
1739 // }
1740 //
1741 bool VM_RedefineClasses::rewrite_cp_refs_in_element_value(
1742 typeArrayHandle annotations_typeArray, int &byte_i_ref, TRAPS) {
1743
1744 if ((byte_i_ref + 1) > annotations_typeArray->length()) {
1745 // not enough room for a tag let alone the rest of an element_value
1746 RC_TRACE_WITH_THREAD(0x02000000, THREAD,
1747 ("length() is too small for a tag"));
1748 return false;
1749 }
1750
1751 u1 tag = annotations_typeArray->byte_at(byte_i_ref);
1752 byte_i_ref++;
1753 RC_TRACE_WITH_THREAD(0x02000000, THREAD, ("tag='%c'", tag));
1754
1755 switch (tag) {
1756 // These BaseType tag values are from Table 4.2 in VM spec:
1757 case 'B': // byte
1758 case 'C': // char
1759 case 'D': // double
1760 case 'F': // float
1761 case 'I': // int
1762 case 'J': // long
1763 case 'S': // short
1764 case 'Z': // boolean
1765
1766 // The remaining tag values are from Table 4.8 in the 2nd-edition of
1767 // the VM spec:
1768 case 's':
1769 {
1770 // For the above tag values (including the BaseType values),
1771 // value.const_value_index is right union field.
1772
1773 if ((byte_i_ref + 2) > annotations_typeArray->length()) {
1774 // not enough room for a const_value_index
1775 RC_TRACE_WITH_THREAD(0x02000000, THREAD,
1776 ("length() is too small for a const_value_index"));
1777 return false;
1778 }
1779
1780 u2 const_value_index = rewrite_cp_ref_in_annotation_data(
1781 annotations_typeArray, byte_i_ref,
1782 "mapped old const_value_index=%d", THREAD);
1783
1784 RC_TRACE_WITH_THREAD(0x02000000, THREAD,
1785 ("const_value_index=%d", const_value_index));
1786 } break;
1787
1788 case 'e':
1789 {
1790 // for the above tag value, value.enum_const_value is right union field
1791
1792 if ((byte_i_ref + 4) > annotations_typeArray->length()) {
1793 // not enough room for a enum_const_value
1794 RC_TRACE_WITH_THREAD(0x02000000, THREAD,
1795 ("length() is too small for a enum_const_value"));
1796 return false;
1797 }
1798
1799 u2 type_name_index = rewrite_cp_ref_in_annotation_data(
1800 annotations_typeArray, byte_i_ref,
1801 "mapped old type_name_index=%d", THREAD);
1802
1803 u2 const_name_index = rewrite_cp_ref_in_annotation_data(
1804 annotations_typeArray, byte_i_ref,
1805 "mapped old const_name_index=%d", THREAD);
1806
1807 RC_TRACE_WITH_THREAD(0x02000000, THREAD,
1808 ("type_name_index=%d const_name_index=%d", type_name_index,
1809 const_name_index));
1810 } break;
1811
1812 case 'c':
1813 {
1814 // for the above tag value, value.class_info_index is right union field
1815
1816 if ((byte_i_ref + 2) > annotations_typeArray->length()) {
1817 // not enough room for a class_info_index
1818 RC_TRACE_WITH_THREAD(0x02000000, THREAD,
1819 ("length() is too small for a class_info_index"));
1820 return false;
1821 }
1822
1823 u2 class_info_index = rewrite_cp_ref_in_annotation_data(
1824 annotations_typeArray, byte_i_ref,
1825 "mapped old class_info_index=%d", THREAD);
1826
1827 RC_TRACE_WITH_THREAD(0x02000000, THREAD,
1828 ("class_info_index=%d", class_info_index));
1829 } break;
1830
1831 case '@':
1832 // For the above tag value, value.attr_value is the right union
1833 // field. This is a nested annotation.
1834 if (!rewrite_cp_refs_in_annotation_struct(annotations_typeArray,
1835 byte_i_ref, THREAD)) {
1836 // propagate failure back to caller
1837 return false;
1838 }
1839 break;
1840
1841 case '[':
1842 {
1843 if ((byte_i_ref + 2) > annotations_typeArray->length()) {
1844 // not enough room for a num_values field
1845 RC_TRACE_WITH_THREAD(0x02000000, THREAD,
1846 ("length() is too small for a num_values field"));
1847 return false;
1848 }
1849
1850 // For the above tag value, value.array_value is the right union
1851 // field. This is an array of nested element_value.
1852 u2 num_values = Bytes::get_Java_u2((address)
1853 annotations_typeArray->byte_at_addr(byte_i_ref));
1854 byte_i_ref += 2;
1855 RC_TRACE_WITH_THREAD(0x02000000, THREAD, ("num_values=%d", num_values));
1856
1857 int calc_num_values = 0;
1858 for (; calc_num_values < num_values; calc_num_values++) {
1859 if (!rewrite_cp_refs_in_element_value(
1860 annotations_typeArray, byte_i_ref, THREAD)) {
1861 RC_TRACE_WITH_THREAD(0x02000000, THREAD,
1862 ("bad nested element_value at %d", calc_num_values));
1863 // propagate failure back to caller
1864 return false;
1865 }
1866 }
1867 assert(num_values == calc_num_values, "sanity check");
1868 } break;
1869
1870 default:
1871 RC_TRACE_WITH_THREAD(0x02000000, THREAD, ("bad tag=0x%x", tag));
1872 return false;
1873 } // end decode tag field
1874
1875 return true;
1876 } // end rewrite_cp_refs_in_element_value()
1877
1878
1879 // Rewrite constant pool references in a fields_annotations field.
1880 bool VM_RedefineClasses::rewrite_cp_refs_in_fields_annotations(
1881 instanceKlassHandle scratch_class, TRAPS) {
1882
1883 objArrayHandle fields_annotations(THREAD,
1884 scratch_class->fields_annotations());
1885
1886 if (fields_annotations.is_null() || fields_annotations->length() == 0) {
1887 // no fields_annotations so nothing to do
1888 return true;
1889 }
1890
1891 RC_TRACE_WITH_THREAD(0x02000000, THREAD,
1892 ("fields_annotations length=%d", fields_annotations->length()));
1893
1894 for (int i = 0; i < fields_annotations->length(); i++) {
1895 typeArrayHandle field_annotations(THREAD,
1896 (typeArrayOop)fields_annotations->obj_at(i));
1897 if (field_annotations.is_null() || field_annotations->length() == 0) {
1898 // this field does not have any annotations so skip it
1899 continue;
1900 }
1901
1902 int byte_i = 0; // byte index into field_annotations
1903 if (!rewrite_cp_refs_in_annotations_typeArray(field_annotations, byte_i,
1904 THREAD)) {
1905 RC_TRACE_WITH_THREAD(0x02000000, THREAD,
1906 ("bad field_annotations at %d", i));
1907 // propagate failure back to caller
1908 return false;
1909 }
1910 }
1911
1912 return true;
1913 } // end rewrite_cp_refs_in_fields_annotations()
1914
1915
1916 // Rewrite constant pool references in a methods_annotations field.
1917 bool VM_RedefineClasses::rewrite_cp_refs_in_methods_annotations(
1918 instanceKlassHandle scratch_class, TRAPS) {
1919
1920 objArrayHandle methods_annotations(THREAD,
1921 scratch_class->methods_annotations());
1922
1923 if (methods_annotations.is_null() || methods_annotations->length() == 0) {
1924 // no methods_annotations so nothing to do
1925 return true;
1926 }
1927
1928 RC_TRACE_WITH_THREAD(0x02000000, THREAD,
1929 ("methods_annotations length=%d", methods_annotations->length()));
1930
1931 for (int i = 0; i < methods_annotations->length(); i++) {
1932 typeArrayHandle method_annotations(THREAD,
1933 (typeArrayOop)methods_annotations->obj_at(i));
1934 if (method_annotations.is_null() || method_annotations->length() == 0) {
1935 // this method does not have any annotations so skip it
1936 continue;
1937 }
1938
1939 int byte_i = 0; // byte index into method_annotations
1940 if (!rewrite_cp_refs_in_annotations_typeArray(method_annotations, byte_i,
1941 THREAD)) {
1942 RC_TRACE_WITH_THREAD(0x02000000, THREAD,
1943 ("bad method_annotations at %d", i));
1944 // propagate failure back to caller
1945 return false;
1946 }
1947 }
1948
1949 return true;
1950 } // end rewrite_cp_refs_in_methods_annotations()
1951
1952
1953 // Rewrite constant pool references in a methods_parameter_annotations
1954 // field. This "structure" is adapted from the
1955 // RuntimeVisibleParameterAnnotations_attribute described in section
1956 // 4.8.17 of the 2nd-edition of the VM spec:
1957 //
1958 // methods_parameter_annotations_typeArray {
1959 // u1 num_parameters;
1960 // {
1961 // u2 num_annotations;
1962 // annotation annotations[num_annotations];
1963 // } parameter_annotations[num_parameters];
1964 // }
1965 //
1966 bool VM_RedefineClasses::rewrite_cp_refs_in_methods_parameter_annotations(
1967 instanceKlassHandle scratch_class, TRAPS) {
1968
1969 objArrayHandle methods_parameter_annotations(THREAD,
1970 scratch_class->methods_parameter_annotations());
1971
1972 if (methods_parameter_annotations.is_null()
1973 || methods_parameter_annotations->length() == 0) {
1974 // no methods_parameter_annotations so nothing to do
1975 return true;
1976 }
1977
1978 RC_TRACE_WITH_THREAD(0x02000000, THREAD,
1979 ("methods_parameter_annotations length=%d",
1980 methods_parameter_annotations->length()));
1981
1982 for (int i = 0; i < methods_parameter_annotations->length(); i++) {
1983 typeArrayHandle method_parameter_annotations(THREAD,
1984 (typeArrayOop)methods_parameter_annotations->obj_at(i));
1985 if (method_parameter_annotations.is_null()
1986 || method_parameter_annotations->length() == 0) {
1987 // this method does not have any parameter annotations so skip it
1988 continue;
1989 }
1990
1991 if (method_parameter_annotations->length() < 1) {
1992 // not enough room for a num_parameters field
1993 RC_TRACE_WITH_THREAD(0x02000000, THREAD,
1994 ("length() is too small for a num_parameters field at %d", i));
1995 return false;
1996 }
1997
1998 int byte_i = 0; // byte index into method_parameter_annotations
1999
2000 u1 num_parameters = method_parameter_annotations->byte_at(byte_i);
2001 byte_i++;
2002
2003 RC_TRACE_WITH_THREAD(0x02000000, THREAD,
2004 ("num_parameters=%d", num_parameters));
2005
2006 int calc_num_parameters = 0;
2007 for (; calc_num_parameters < num_parameters; calc_num_parameters++) {
2008 if (!rewrite_cp_refs_in_annotations_typeArray(
2009 method_parameter_annotations, byte_i, THREAD)) {
2010 RC_TRACE_WITH_THREAD(0x02000000, THREAD,
2011 ("bad method_parameter_annotations at %d", calc_num_parameters));
2012 // propagate failure back to caller
2013 return false;
2014 }
2015 }
2016 assert(num_parameters == calc_num_parameters, "sanity check");
2017 }
2018
2019 return true;
2020 } // end rewrite_cp_refs_in_methods_parameter_annotations()
2021
2022
2023 // Rewrite constant pool references in a methods_default_annotations
2024 // field. This "structure" is adapted from the AnnotationDefault_attribute
2025 // that is described in section 4.8.19 of the 2nd-edition of the VM spec:
2026 //
2027 // methods_default_annotations_typeArray {
2028 // element_value default_value;
2029 // }
2030 //
2031 bool VM_RedefineClasses::rewrite_cp_refs_in_methods_default_annotations(
2032 instanceKlassHandle scratch_class, TRAPS) {
2033
2034 objArrayHandle methods_default_annotations(THREAD,
2035 scratch_class->methods_default_annotations());
2036
2037 if (methods_default_annotations.is_null()
2038 || methods_default_annotations->length() == 0) {
2039 // no methods_default_annotations so nothing to do
2040 return true;
2041 }
2042
2043 RC_TRACE_WITH_THREAD(0x02000000, THREAD,
2044 ("methods_default_annotations length=%d",
2045 methods_default_annotations->length()));
2046
2047 for (int i = 0; i < methods_default_annotations->length(); i++) {
2048 typeArrayHandle method_default_annotations(THREAD,
2049 (typeArrayOop)methods_default_annotations->obj_at(i));
2050 if (method_default_annotations.is_null()
2051 || method_default_annotations->length() == 0) {
2052 // this method does not have any default annotations so skip it
2053 continue;
2054 }
2055
2056 int byte_i = 0; // byte index into method_default_annotations
2057
2058 if (!rewrite_cp_refs_in_element_value(
2059 method_default_annotations, byte_i, THREAD)) {
2060 RC_TRACE_WITH_THREAD(0x02000000, THREAD,
2061 ("bad default element_value at %d", i));
2062 // propagate failure back to caller
2063 return false;
2064 }
2065 }
2066
2067 return true;
2068 } // end rewrite_cp_refs_in_methods_default_annotations()
2069
2070
2071 // Rewrite constant pool references in the method's stackmap table.
2072 // These "structures" are adapted from the StackMapTable_attribute that
2073 // is described in section 4.8.4 of the 6.0 version of the VM spec
2074 // (dated 2005.10.26):
2075 // file:///net/quincunx.sfbay/export/gbracha/ClassFile-Java6.pdf
2076 //
2077 // stack_map {
2078 // u2 number_of_entries;
2079 // stack_map_frame entries[number_of_entries];
2080 // }
2081 //
2082 void VM_RedefineClasses::rewrite_cp_refs_in_stack_map_table(
2083 methodHandle method, TRAPS) {
2084
2085 if (!method->has_stackmap_table()) {
2086 return;
2087 }
2088
2089 typeArrayOop stackmap_data = method->stackmap_data();
2090 address stackmap_p = (address)stackmap_data->byte_at_addr(0);
2091 address stackmap_end = stackmap_p + stackmap_data->length();
2092
2093 assert(stackmap_p + 2 <= stackmap_end, "no room for number_of_entries");
2094 u2 number_of_entries = Bytes::get_Java_u2(stackmap_p);
2095 stackmap_p += 2;
2096
2097 RC_TRACE_WITH_THREAD(0x04000000, THREAD,
2098 ("number_of_entries=%u", number_of_entries));
2099
2100 // walk through each stack_map_frame
2101 u2 calc_number_of_entries = 0;
2102 for (; calc_number_of_entries < number_of_entries; calc_number_of_entries++) {
2103 // The stack_map_frame structure is a u1 frame_type followed by
2104 // 0 or more bytes of data:
2105 //
2106 // union stack_map_frame {
2107 // same_frame;
2108 // same_locals_1_stack_item_frame;
2109 // same_locals_1_stack_item_frame_extended;
2110 // chop_frame;
2111 // same_frame_extended;
2112 // append_frame;
2113 // full_frame;
2114 // }
2115
2116 assert(stackmap_p + 1 <= stackmap_end, "no room for frame_type");
2117 // The Linux compiler does not like frame_type to be u1 or u2. It
2118 // issues the following warning for the first if-statement below:
2119 //
2120 // "warning: comparison is always true due to limited range of data type"
2121 //
2122 u4 frame_type = *stackmap_p;
2123 stackmap_p++;
2124
2125 // same_frame {
2126 // u1 frame_type = SAME; /* 0-63 */
2127 // }
2128 if (frame_type >= 0 && frame_type <= 63) {
2129 // nothing more to do for same_frame
2130 }
2131
2132 // same_locals_1_stack_item_frame {
2133 // u1 frame_type = SAME_LOCALS_1_STACK_ITEM; /* 64-127 */
2134 // verification_type_info stack[1];
2135 // }
2136 else if (frame_type >= 64 && frame_type <= 127) {
2137 rewrite_cp_refs_in_verification_type_info(stackmap_p, stackmap_end,
2138 calc_number_of_entries, frame_type, THREAD);
2139 }
2140
2141 // reserved for future use
2142 else if (frame_type >= 128 && frame_type <= 246) {
2143 // nothing more to do for reserved frame_types
2144 }
2145
2146 // same_locals_1_stack_item_frame_extended {
2147 // u1 frame_type = SAME_LOCALS_1_STACK_ITEM_EXTENDED; /* 247 */
2148 // u2 offset_delta;
2149 // verification_type_info stack[1];
2150 // }
2151 else if (frame_type == 247) {
2152 stackmap_p += 2;
2153 rewrite_cp_refs_in_verification_type_info(stackmap_p, stackmap_end,
2154 calc_number_of_entries, frame_type, THREAD);
2155 }
2156
2157 // chop_frame {
2158 // u1 frame_type = CHOP; /* 248-250 */
2159 // u2 offset_delta;
2160 // }
2161 else if (frame_type >= 248 && frame_type <= 250) {
2162 stackmap_p += 2;
2163 }
2164
2165 // same_frame_extended {
2166 // u1 frame_type = SAME_FRAME_EXTENDED; /* 251*/
2167 // u2 offset_delta;
2168 // }
2169 else if (frame_type == 251) {
2170 stackmap_p += 2;
2171 }
2172
2173 // append_frame {
2174 // u1 frame_type = APPEND; /* 252-254 */
2175 // u2 offset_delta;
2176 // verification_type_info locals[frame_type - 251];
2177 // }
2178 else if (frame_type >= 252 && frame_type <= 254) {
2179 assert(stackmap_p + 2 <= stackmap_end,
2180 "no room for offset_delta");
2181 stackmap_p += 2;
2182 u1 len = frame_type - 251;
2183 for (u1 i = 0; i < len; i++) {
2184 rewrite_cp_refs_in_verification_type_info(stackmap_p, stackmap_end,
2185 calc_number_of_entries, frame_type, THREAD);
2186 }
2187 }
2188
2189 // full_frame {
2190 // u1 frame_type = FULL_FRAME; /* 255 */
2191 // u2 offset_delta;
2192 // u2 number_of_locals;
2193 // verification_type_info locals[number_of_locals];
2194 // u2 number_of_stack_items;
2195 // verification_type_info stack[number_of_stack_items];
2196 // }
2197 else if (frame_type == 255) {
2198 assert(stackmap_p + 2 + 2 <= stackmap_end,
2199 "no room for smallest full_frame");
2200 stackmap_p += 2;
2201
2202 u2 number_of_locals = Bytes::get_Java_u2(stackmap_p);
2203 stackmap_p += 2;
2204
2205 for (u2 locals_i = 0; locals_i < number_of_locals; locals_i++) {
2206 rewrite_cp_refs_in_verification_type_info(stackmap_p, stackmap_end,
2207 calc_number_of_entries, frame_type, THREAD);
2208 }
2209
2210 // Use the largest size for the number_of_stack_items, but only get
2211 // the right number of bytes.
2212 u2 number_of_stack_items = Bytes::get_Java_u2(stackmap_p);
2213 stackmap_p += 2;
2214
2215 for (u2 stack_i = 0; stack_i < number_of_stack_items; stack_i++) {
2216 rewrite_cp_refs_in_verification_type_info(stackmap_p, stackmap_end,
2217 calc_number_of_entries, frame_type, THREAD);
2218 }
2219 }
2220 } // end while there is a stack_map_frame
2221 assert(number_of_entries == calc_number_of_entries, "sanity check");
2222 } // end rewrite_cp_refs_in_stack_map_table()
2223
2224
2225 // Rewrite constant pool references in the verification type info
2226 // portion of the method's stackmap table. These "structures" are
2227 // adapted from the StackMapTable_attribute that is described in
2228 // section 4.8.4 of the 6.0 version of the VM spec (dated 2005.10.26):
2229 // file:///net/quincunx.sfbay/export/gbracha/ClassFile-Java6.pdf
2230 //
2231 // The verification_type_info structure is a u1 tag followed by 0 or
2232 // more bytes of data:
2233 //
2234 // union verification_type_info {
2235 // Top_variable_info;
2236 // Integer_variable_info;
2237 // Float_variable_info;
2238 // Long_variable_info;
2239 // Double_variable_info;
2240 // Null_variable_info;
2241 // UninitializedThis_variable_info;
2242 // Object_variable_info;
2243 // Uninitialized_variable_info;
2244 // }
2245 //
2246 void VM_RedefineClasses::rewrite_cp_refs_in_verification_type_info(
2247 address& stackmap_p_ref, address stackmap_end, u2 frame_i,
2248 u1 frame_type, TRAPS) {
2249
2250 assert(stackmap_p_ref + 1 <= stackmap_end, "no room for tag");
2251 u1 tag = *stackmap_p_ref;
2252 stackmap_p_ref++;
2253
2254 switch (tag) {
2255 // Top_variable_info {
2256 // u1 tag = ITEM_Top; /* 0 */
2257 // }
2258 // verificationType.hpp has zero as ITEM_Bogus instead of ITEM_Top
2259 case 0: // fall through
2260
2261 // Integer_variable_info {
2262 // u1 tag = ITEM_Integer; /* 1 */
2263 // }
2264 case ITEM_Integer: // fall through
2265
2266 // Float_variable_info {
2267 // u1 tag = ITEM_Float; /* 2 */
2268 // }
2269 case ITEM_Float: // fall through
2270
2271 // Double_variable_info {
2272 // u1 tag = ITEM_Double; /* 3 */
2273 // }
2274 case ITEM_Double: // fall through
2275
2276 // Long_variable_info {
2277 // u1 tag = ITEM_Long; /* 4 */
2278 // }
2279 case ITEM_Long: // fall through
2280
2281 // Null_variable_info {
2282 // u1 tag = ITEM_Null; /* 5 */
2283 // }
2284 case ITEM_Null: // fall through
2285
2286 // UninitializedThis_variable_info {
2287 // u1 tag = ITEM_UninitializedThis; /* 6 */
2288 // }
2289 case ITEM_UninitializedThis:
2290 // nothing more to do for the above tag types
2291 break;
2292
2293 // Object_variable_info {
2294 // u1 tag = ITEM_Object; /* 7 */
2295 // u2 cpool_index;
2296 // }
2297 case ITEM_Object:
2298 {
2299 assert(stackmap_p_ref + 2 <= stackmap_end, "no room for cpool_index");
2300 u2 cpool_index = Bytes::get_Java_u2(stackmap_p_ref);
2301 u2 new_cp_index = find_new_index(cpool_index);
2302 if (new_cp_index != 0) {
2303 RC_TRACE_WITH_THREAD(0x04000000, THREAD,
2304 ("mapped old cpool_index=%d", cpool_index));
2305 Bytes::put_Java_u2(stackmap_p_ref, new_cp_index);
2306 cpool_index = new_cp_index;
2307 }
2308 stackmap_p_ref += 2;
2309
2310 RC_TRACE_WITH_THREAD(0x04000000, THREAD,
2311 ("frame_i=%u, frame_type=%u, cpool_index=%d", frame_i,
2312 frame_type, cpool_index));
2313 } break;
2314
2315 // Uninitialized_variable_info {
2316 // u1 tag = ITEM_Uninitialized; /* 8 */
2317 // u2 offset;
2318 // }
2319 case ITEM_Uninitialized:
2320 assert(stackmap_p_ref + 2 <= stackmap_end, "no room for offset");
2321 stackmap_p_ref += 2;
2322 break;
2323
2324 default:
2325 RC_TRACE_WITH_THREAD(0x04000000, THREAD,
2326 ("frame_i=%u, frame_type=%u, bad tag=0x%x", frame_i, frame_type, tag));
2327 ShouldNotReachHere();
2328 break;
2329 } // end switch (tag)
2330 } // end rewrite_cp_refs_in_verification_type_info()
2331
2332
2333 // Change the constant pool associated with klass scratch_class to
2334 // scratch_cp. If shrink is true, then scratch_cp_length elements
2335 // are copied from scratch_cp to a smaller constant pool and the
2336 // smaller constant pool is associated with scratch_class.
2337 void VM_RedefineClasses::set_new_constant_pool(
2338 instanceKlassHandle scratch_class, constantPoolHandle scratch_cp,
2339 int scratch_cp_length, bool shrink, TRAPS) {
2340 assert(!shrink || scratch_cp->length() >= scratch_cp_length, "sanity check");
2341
2342 if (shrink) {
2343 // scratch_cp is a merged constant pool and has enough space for a
2344 // worst case merge situation. We want to associate the minimum
2345 // sized constant pool with the klass to save space.
2346 constantPoolHandle smaller_cp(THREAD,
2347 oopFactory::new_constantPool(scratch_cp_length,
2348 oopDesc::IsUnsafeConc,
2349 THREAD));
2350 // preserve orig_length() value in the smaller copy
2351 int orig_length = scratch_cp->orig_length();
2352 assert(orig_length != 0, "sanity check");
2353 smaller_cp->set_orig_length(orig_length);
2354 scratch_cp->copy_cp_to(1, scratch_cp_length - 1, smaller_cp, 1, THREAD);
2355 scratch_cp = smaller_cp;
2356 smaller_cp()->set_is_conc_safe(true);
2357 }
2358
2359 // attach new constant pool to klass
2360 scratch_cp->set_pool_holder(scratch_class());
2361
2362 // attach klass to new constant pool
2363 scratch_class->set_constants(scratch_cp());
2364
2365 int i; // for portability
2366
2367 // update each field in klass to use new constant pool indices as needed
2368 for (JavaFieldStream fs(scratch_class); !fs.done(); fs.next()) {
2369 jshort cur_index = fs.name_index();
2370 jshort new_index = find_new_index(cur_index);
2371 if (new_index != 0) {
2372 RC_TRACE_WITH_THREAD(0x00080000, THREAD,
2373 ("field-name_index change: %d to %d", cur_index, new_index));
2374 fs.set_name_index(new_index);
2375 }
2376 cur_index = fs.signature_index();
2377 new_index = find_new_index(cur_index);
2378 if (new_index != 0) {
2379 RC_TRACE_WITH_THREAD(0x00080000, THREAD,
2380 ("field-signature_index change: %d to %d", cur_index, new_index));
2381 fs.set_signature_index(new_index);
2382 }
2383 cur_index = fs.initval_index();
2384 new_index = find_new_index(cur_index);
2385 if (new_index != 0) {
2386 RC_TRACE_WITH_THREAD(0x00080000, THREAD,
2387 ("field-initval_index change: %d to %d", cur_index, new_index));
2388 fs.set_initval_index(new_index);
2389 }
2390 cur_index = fs.generic_signature_index();
2391 new_index = find_new_index(cur_index);
2392 if (new_index != 0) {
2393 RC_TRACE_WITH_THREAD(0x00080000, THREAD,
2394 ("field-generic_signature change: %d to %d", cur_index, new_index));
2395 fs.set_generic_signature_index(new_index);
2396 }
2397 } // end for each field
2398
2399 // Update constant pool indices in the inner classes info to use
2400 // new constant indices as needed. The inner classes info is a
2401 // quadruple:
2402 // (inner_class_info, outer_class_info, inner_name, inner_access_flags)
2403 InnerClassesIterator iter(scratch_class);
2404 for (; !iter.done(); iter.next()) {
2405 int cur_index = iter.inner_class_info_index();
2406 if (cur_index == 0) {
2407 continue; // JVM spec. allows null inner class refs so skip it
2408 }
2409 int new_index = find_new_index(cur_index);
2410 if (new_index != 0) {
2411 RC_TRACE_WITH_THREAD(0x00080000, THREAD,
2412 ("inner_class_info change: %d to %d", cur_index, new_index));
2413 iter.set_inner_class_info_index(new_index);
2414 }
2415 cur_index = iter.outer_class_info_index();
2416 new_index = find_new_index(cur_index);
2417 if (new_index != 0) {
2418 RC_TRACE_WITH_THREAD(0x00080000, THREAD,
2419 ("outer_class_info change: %d to %d", cur_index, new_index));
2420 iter.set_outer_class_info_index(new_index);
2421 }
2422 cur_index = iter.inner_name_index();
2423 new_index = find_new_index(cur_index);
2424 if (new_index != 0) {
2425 RC_TRACE_WITH_THREAD(0x00080000, THREAD,
2426 ("inner_name change: %d to %d", cur_index, new_index));
2427 iter.set_inner_name_index(new_index);
2428 }
2429 } // end for each inner class
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
2482 ExceptionTable ex_table(method());
2483 int ext_length = ex_table.length();
2484
2485 for (int j = 0; j < ext_length; j ++) {
2486 int cur_index = ex_table.catch_type_index(j);
2487 int new_index = find_new_index(cur_index);
2488 if (new_index != 0) {
2489 RC_TRACE_WITH_THREAD(0x00080000, THREAD,
2490 ("ext-klass_index change: %d to %d", cur_index, new_index));
2491 ex_table.set_catch_type_index(j, new_index);
2492 }
2493 } // end for each exception table entry
2494
2495 // Update constant pool indices in the method's local variable
2496 // table to use new constant indices as needed. The local variable
2497 // table hold sextuple entries of the form:
2498 // (start_pc, length, name_index, descriptor_index, signature_index, slot)
2499 int lvt_length = method->localvariable_table_length();
2500 if (lvt_length > 0) {
2501 LocalVariableTableElement * lv_table =
2502 method->localvariable_table_start();
2503 for (int j = 0; j < lvt_length; j++) {
2504 int cur_index = lv_table[j].name_cp_index;
2505 int new_index = find_new_index(cur_index);
2506 if (new_index != 0) {
2507 RC_TRACE_WITH_THREAD(0x00080000, THREAD,
2508 ("lvt-name_cp_index change: %d to %d", cur_index, new_index));
2509 lv_table[j].name_cp_index = (u2)new_index;
2510 }
2511 cur_index = lv_table[j].descriptor_cp_index;
2512 new_index = find_new_index(cur_index);
2513 if (new_index != 0) {
2514 RC_TRACE_WITH_THREAD(0x00080000, THREAD,
2515 ("lvt-descriptor_cp_index change: %d to %d", cur_index,
2516 new_index));
2517 lv_table[j].descriptor_cp_index = (u2)new_index;
2518 }
2519 cur_index = lv_table[j].signature_cp_index;
2520 new_index = find_new_index(cur_index);
2521 if (new_index != 0) {
2522 RC_TRACE_WITH_THREAD(0x00080000, THREAD,
2523 ("lvt-signature_cp_index change: %d to %d", cur_index, new_index));
2524 lv_table[j].signature_cp_index = (u2)new_index;
2525 }
2526 } // end for each local variable table entry
2527 } // end if there are local variable table entries
2528
2529 rewrite_cp_refs_in_stack_map_table(method, THREAD);
2530 } // end for each method
2531 assert(scratch_cp()->is_conc_safe(), "Just checking");
2532 } // end set_new_constant_pool()
2533
2534
2535 // Unevolving classes may point to methods of the_class directly
2536 // from their constant pool caches, itables, and/or vtables. We
2537 // use the SystemDictionary::classes_do() facility and this helper
2538 // to fix up these pointers.
2539 //
2540 // Note: We currently don't support updating the vtable in
2541 // arrayKlassOops. See Open Issues in jvmtiRedefineClasses.hpp.
2542 void VM_RedefineClasses::adjust_cpool_cache_and_vtable(klassOop k_oop,
2543 oop initiating_loader, TRAPS) {
2544 Klass *k = k_oop->klass_part();
2545 if (k->oop_is_instance()) {
2546 HandleMark hm(THREAD);
2547 instanceKlass *ik = (instanceKlass *) k;
2548
2549 // HotSpot specific optimization! HotSpot does not currently
2550 // support delegation from the bootstrap class loader to a
2551 // user-defined class loader. This means that if the bootstrap
2552 // class loader is the initiating class loader, then it will also
2553 // be the defining class loader. This also means that classes
2554 // loaded by the bootstrap class loader cannot refer to classes
2555 // loaded by a user-defined class loader. Note: a user-defined
2556 // class loader can delegate to the bootstrap class loader.
2557 //
2558 // If the current class being redefined has a user-defined class
2559 // loader as its defining class loader, then we can skip all
2560 // classes loaded by the bootstrap class loader.
2561 bool is_user_defined =
2562 instanceKlass::cast(_the_class_oop)->class_loader() != NULL;
2563 if (is_user_defined && ik->class_loader() == NULL) {
2564 return;
2565 }
2566
2567 // This is a very busy routine. We don't want too much tracing
2568 // printed out.
2569 bool trace_name_printed = false;
2570
2571 // Very noisy: only enable this call if you are trying to determine
2572 // that a specific class gets found by this routine.
2573 // RC_TRACE macro has an embedded ResourceMark
2574 // RC_TRACE_WITH_THREAD(0x00100000, THREAD,
2575 // ("adjust check: name=%s", ik->external_name()));
2576 // trace_name_printed = true;
2577
2578 // Fix the vtable embedded in the_class and subclasses of the_class,
2579 // if one exists. We discard scratch_class and we don't keep an
2580 // instanceKlass around to hold obsolete methods so we don't have
2581 // any other instanceKlass embedded vtables to update. The vtable
2582 // holds the methodOops for virtual (but not final) methods.
2583 if (ik->vtable_length() > 0 && ik->is_subtype_of(_the_class_oop)) {
2584 // ik->vtable() creates a wrapper object; rm cleans it up
2585 ResourceMark rm(THREAD);
2586 ik->vtable()->adjust_method_entries(_matching_old_methods,
2587 _matching_new_methods,
2588 _matching_methods_length,
2589 &trace_name_printed);
2590 }
2591
2592 // If the current class has an itable and we are either redefining an
2593 // interface or if the current class is a subclass of the_class, then
2594 // we potentially have to fix the itable. If we are redefining an
2595 // interface, then we have to call adjust_method_entries() for
2596 // every instanceKlass that has an itable since there isn't a
2597 // subclass relationship between an interface and an instanceKlass.
2598 if (ik->itable_length() > 0 && (Klass::cast(_the_class_oop)->is_interface()
2599 || ik->is_subclass_of(_the_class_oop))) {
2600 // ik->itable() creates a wrapper object; rm cleans it up
2601 ResourceMark rm(THREAD);
2602 ik->itable()->adjust_method_entries(_matching_old_methods,
2603 _matching_new_methods,
2604 _matching_methods_length,
2605 &trace_name_printed);
2606 }
2607
2608 // The constant pools in other classes (other_cp) can refer to
2609 // methods in the_class. We have to update method information in
2610 // other_cp's cache. If other_cp has a previous version, then we
2611 // have to repeat the process for each previous version. The
2612 // constant pool cache holds the methodOops for non-virtual
2613 // methods and for virtual, final methods.
2614 //
2615 // Special case: if the current class is the_class, then new_cp
2616 // has already been attached to the_class and old_cp has already
2617 // been added as a previous version. The new_cp doesn't have any
2618 // cached references to old methods so it doesn't need to be
2619 // updated. We can simply start with the previous version(s) in
2620 // that case.
2621 constantPoolHandle other_cp;
2622 constantPoolCacheOop cp_cache;
2623
2624 if (k_oop != _the_class_oop) {
2625 // this klass' constant pool cache may need adjustment
2626 other_cp = constantPoolHandle(ik->constants());
2627 cp_cache = other_cp->cache();
2628 if (cp_cache != NULL) {
2629 cp_cache->adjust_method_entries(_matching_old_methods,
2630 _matching_new_methods,
2631 _matching_methods_length,
2632 &trace_name_printed);
2633 }
2634 }
2635 {
2636 ResourceMark rm(THREAD);
2637 // PreviousVersionInfo objects returned via PreviousVersionWalker
2638 // contain a GrowableArray of handles. We have to clean up the
2639 // GrowableArray _after_ the PreviousVersionWalker destructor
2640 // has destroyed the handles.
2641 {
2642 // the previous versions' constant pool caches may need adjustment
2643 PreviousVersionWalker pvw(ik);
2644 for (PreviousVersionInfo * pv_info = pvw.next_previous_version();
2645 pv_info != NULL; pv_info = pvw.next_previous_version()) {
2646 other_cp = pv_info->prev_constant_pool_handle();
2647 cp_cache = other_cp->cache();
2648 if (cp_cache != NULL) {
2649 cp_cache->adjust_method_entries(_matching_old_methods,
2650 _matching_new_methods,
2651 _matching_methods_length,
2652 &trace_name_printed);
2653 }
2654 }
2655 } // pvw is cleaned up
2656 } // rm is cleaned up
2657 }
2658 }
2659
2660 void VM_RedefineClasses::update_jmethod_ids() {
2661 for (int j = 0; j < _matching_methods_length; ++j) {
2662 methodOop old_method = _matching_old_methods[j];
2663 jmethodID jmid = old_method->find_jmethod_id_or_null();
2664 if (jmid != NULL) {
2665 // There is a jmethodID, change it to point to the new method
2666 methodHandle new_method_h(_matching_new_methods[j]);
2667 JNIHandles::change_method_associated_with_jmethod_id(jmid, new_method_h);
2668 assert(JNIHandles::resolve_jmethod_id(jmid) == _matching_new_methods[j],
2669 "should be replaced");
2670 }
2671 }
2672 }
2673
2674 void VM_RedefineClasses::check_methods_and_mark_as_obsolete(
2675 BitMap *emcp_methods, int * emcp_method_count_p) {
2676 *emcp_method_count_p = 0;
2677 int obsolete_count = 0;
2678 int old_index = 0;
2679 for (int j = 0; j < _matching_methods_length; ++j, ++old_index) {
2680 methodOop old_method = _matching_old_methods[j];
2681 methodOop new_method = _matching_new_methods[j];
2682 methodOop old_array_method;
2683
2684 // Maintain an old_index into the _old_methods array by skipping
2685 // deleted methods
2686 while ((old_array_method = (methodOop) _old_methods->obj_at(old_index))
2687 != old_method) {
2688 ++old_index;
2689 }
2690
2691 if (MethodComparator::methods_EMCP(old_method, new_method)) {
2692 // The EMCP definition from JSR-163 requires the bytecodes to be
2693 // the same with the exception of constant pool indices which may
2694 // differ. However, the constants referred to by those indices
2695 // must be the same.
2696 //
2697 // We use methods_EMCP() for comparison since constant pool
2698 // merging can remove duplicate constant pool entries that were
2699 // present in the old method and removed from the rewritten new
2700 // method. A faster binary comparison function would consider the
2701 // old and new methods to be different when they are actually
2702 // EMCP.
2703 //
2704 // The old and new methods are EMCP and you would think that we
2705 // could get rid of one of them here and now and save some space.
2706 // However, the concept of EMCP only considers the bytecodes and
2707 // the constant pool entries in the comparison. Other things,
2708 // e.g., the line number table (LNT) or the local variable table
2709 // (LVT) don't count in the comparison. So the new (and EMCP)
2710 // method can have a new LNT that we need so we can't just
2711 // overwrite the new method with the old method.
2712 //
2713 // When this routine is called, we have already attached the new
2714 // methods to the_class so the old methods are effectively
2715 // overwritten. However, if an old method is still executing,
2716 // then the old method cannot be collected until sometime after
2717 // the old method call has returned. So the overwriting of old
2718 // methods by new methods will save us space except for those
2719 // (hopefully few) old methods that are still executing.
2720 //
2721 // A method refers to a constMethodOop and this presents another
2722 // possible avenue to space savings. The constMethodOop in the
2723 // new method contains possibly new attributes (LNT, LVT, etc).
2724 // At first glance, it seems possible to save space by replacing
2725 // the constMethodOop in the old method with the constMethodOop
2726 // from the new method. The old and new methods would share the
2727 // same constMethodOop and we would save the space occupied by
2728 // the old constMethodOop. However, the constMethodOop contains
2729 // a back reference to the containing method. Sharing the
2730 // constMethodOop between two methods could lead to confusion in
2731 // the code that uses the back reference. This would lead to
2732 // brittle code that could be broken in non-obvious ways now or
2733 // in the future.
2734 //
2735 // Another possibility is to copy the constMethodOop from the new
2736 // method to the old method and then overwrite the new method with
2737 // the old method. Since the constMethodOop contains the bytecodes
2738 // for the method embedded in the oop, this option would change
2739 // the bytecodes out from under any threads executing the old
2740 // method and make the thread's bcp invalid. Since EMCP requires
2741 // that the bytecodes be the same modulo constant pool indices, it
2742 // is straight forward to compute the correct new bcp in the new
2743 // constMethodOop from the old bcp in the old constMethodOop. The
2744 // time consuming part would be searching all the frames in all
2745 // of the threads to find all of the calls to the old method.
2746 //
2747 // It looks like we will have to live with the limited savings
2748 // that we get from effectively overwriting the old methods
2749 // when the new methods are attached to the_class.
2750
2751 // track which methods are EMCP for add_previous_version() call
2752 emcp_methods->set_bit(old_index);
2753 (*emcp_method_count_p)++;
2754
2755 // An EMCP method is _not_ obsolete. An obsolete method has a
2756 // different jmethodID than the current method. An EMCP method
2757 // has the same jmethodID as the current method. Having the
2758 // same jmethodID for all EMCP versions of a method allows for
2759 // a consistent view of the EMCP methods regardless of which
2760 // EMCP method you happen to have in hand. For example, a
2761 // breakpoint set in one EMCP method will work for all EMCP
2762 // versions of the method including the current one.
2763 } else {
2764 // mark obsolete methods as such
2765 old_method->set_is_obsolete();
2766 obsolete_count++;
2767
2768 // obsolete methods need a unique idnum
2769 u2 num = instanceKlass::cast(_the_class_oop)->next_method_idnum();
2770 if (num != constMethodOopDesc::UNSET_IDNUM) {
2771 // u2 old_num = old_method->method_idnum();
2772 old_method->set_method_idnum(num);
2773 // TO DO: attach obsolete annotations to obsolete method's new idnum
2774 }
2775 // With tracing we try not to "yack" too much. The position of
2776 // this trace assumes there are fewer obsolete methods than
2777 // EMCP methods.
2778 RC_TRACE(0x00000100, ("mark %s(%s) as obsolete",
2779 old_method->name()->as_C_string(),
2780 old_method->signature()->as_C_string()));
2781 }
2782 old_method->set_is_old();
2783 }
2784 for (int i = 0; i < _deleted_methods_length; ++i) {
2785 methodOop old_method = _deleted_methods[i];
2786
2787 assert(old_method->vtable_index() < 0,
2788 "cannot delete methods with vtable entries");;
2789
2790 // Mark all deleted methods as old and obsolete
2791 old_method->set_is_old();
2792 old_method->set_is_obsolete();
2793 ++obsolete_count;
2794 // With tracing we try not to "yack" too much. The position of
2795 // this trace assumes there are fewer obsolete methods than
2796 // EMCP methods.
2797 RC_TRACE(0x00000100, ("mark deleted %s(%s) as obsolete",
2798 old_method->name()->as_C_string(),
2799 old_method->signature()->as_C_string()));
2800 }
2801 assert((*emcp_method_count_p + obsolete_count) == _old_methods->length(),
2802 "sanity check");
2803 RC_TRACE(0x00000100, ("EMCP_cnt=%d, obsolete_cnt=%d", *emcp_method_count_p,
2804 obsolete_count));
2805 }
2806
2807 // This internal class transfers the native function registration from old methods
2808 // to new methods. It is designed to handle both the simple case of unchanged
2809 // native methods and the complex cases of native method prefixes being added and/or
2810 // removed.
2811 // It expects only to be used during the VM_RedefineClasses op (a safepoint).
2812 //
2813 // This class is used after the new methods have been installed in "the_class".
2814 //
2815 // So, for example, the following must be handled. Where 'm' is a method and
2816 // a number followed by an underscore is a prefix.
2817 //
2818 // Old Name New Name
2819 // Simple transfer to new method m -> m
2820 // Add prefix m -> 1_m
2821 // Remove prefix 1_m -> m
2822 // Simultaneous add of prefixes m -> 3_2_1_m
2823 // Simultaneous removal of prefixes 3_2_1_m -> m
2824 // Simultaneous add and remove 1_m -> 2_m
2825 // Same, caused by prefix removal only 3_2_1_m -> 3_2_m
2826 //
2827 class TransferNativeFunctionRegistration {
2828 private:
2829 instanceKlassHandle the_class;
2830 int prefix_count;
2831 char** prefixes;
2832
2833 // Recursively search the binary tree of possibly prefixed method names.
2834 // Iteration could be used if all agents were well behaved. Full tree walk is
2835 // more resilent to agents not cleaning up intermediate methods.
2836 // Branch at each depth in the binary tree is:
2837 // (1) without the prefix.
2838 // (2) with the prefix.
2839 // where 'prefix' is the prefix at that 'depth' (first prefix, second prefix,...)
2840 methodOop search_prefix_name_space(int depth, char* name_str, size_t name_len,
2841 Symbol* signature) {
2842 TempNewSymbol name_symbol = SymbolTable::probe(name_str, (int)name_len);
2843 if (name_symbol != NULL) {
2844 methodOop method = Klass::cast(the_class())->lookup_method(name_symbol, signature);
2845 if (method != NULL) {
2846 // Even if prefixed, intermediate methods must exist.
2847 if (method->is_native()) {
2848 // Wahoo, we found a (possibly prefixed) version of the method, return it.
2849 return method;
2850 }
2851 if (depth < prefix_count) {
2852 // Try applying further prefixes (other than this one).
2853 method = search_prefix_name_space(depth+1, name_str, name_len, signature);
2854 if (method != NULL) {
2855 return method; // found
2856 }
2857
2858 // Try adding this prefix to the method name and see if it matches
2859 // another method name.
2860 char* prefix = prefixes[depth];
2861 size_t prefix_len = strlen(prefix);
2862 size_t trial_len = name_len + prefix_len;
2863 char* trial_name_str = NEW_RESOURCE_ARRAY(char, trial_len + 1);
2864 strcpy(trial_name_str, prefix);
2865 strcat(trial_name_str, name_str);
2866 method = search_prefix_name_space(depth+1, trial_name_str, trial_len,
2867 signature);
2868 if (method != NULL) {
2869 // If found along this branch, it was prefixed, mark as such
2870 method->set_is_prefixed_native();
2871 return method; // found
2872 }
2873 }
2874 }
2875 }
2876 return NULL; // This whole branch bore nothing
2877 }
2878
2879 // Return the method name with old prefixes stripped away.
2880 char* method_name_without_prefixes(methodOop method) {
2881 Symbol* name = method->name();
2882 char* name_str = name->as_utf8();
2883
2884 // Old prefixing may be defunct, strip prefixes, if any.
2885 for (int i = prefix_count-1; i >= 0; i--) {
2886 char* prefix = prefixes[i];
2887 size_t prefix_len = strlen(prefix);
2888 if (strncmp(prefix, name_str, prefix_len) == 0) {
2889 name_str += prefix_len;
2890 }
2891 }
2892 return name_str;
2893 }
2894
2895 // Strip any prefixes off the old native method, then try to find a
2896 // (possibly prefixed) new native that matches it.
2897 methodOop strip_and_search_for_new_native(methodOop method) {
2898 ResourceMark rm;
2899 char* name_str = method_name_without_prefixes(method);
2900 return search_prefix_name_space(0, name_str, strlen(name_str),
2901 method->signature());
2902 }
2903
2904 public:
2905
2906 // Construct a native method transfer processor for this class.
2907 TransferNativeFunctionRegistration(instanceKlassHandle _the_class) {
2908 assert(SafepointSynchronize::is_at_safepoint(), "sanity check");
2909
2910 the_class = _the_class;
2911 prefixes = JvmtiExport::get_all_native_method_prefixes(&prefix_count);
2912 }
2913
2914 // Attempt to transfer any of the old or deleted methods that are native
2915 void transfer_registrations(methodOop* old_methods, int methods_length) {
2916 for (int j = 0; j < methods_length; j++) {
2917 methodOop old_method = old_methods[j];
2918
2919 if (old_method->is_native() && old_method->has_native_function()) {
2920 methodOop new_method = strip_and_search_for_new_native(old_method);
2921 if (new_method != NULL) {
2922 // Actually set the native function in the new method.
2923 // Redefine does not send events (except CFLH), certainly not this
2924 // behind the scenes re-registration.
2925 new_method->set_native_function(old_method->native_function(),
2926 !methodOopDesc::native_bind_event_is_interesting);
2927 }
2928 }
2929 }
2930 }
2931 };
2932
2933 // Don't lose the association between a native method and its JNI function.
2934 void VM_RedefineClasses::transfer_old_native_function_registrations(instanceKlassHandle the_class) {
2935 TransferNativeFunctionRegistration transfer(the_class);
2936 transfer.transfer_registrations(_deleted_methods, _deleted_methods_length);
2937 transfer.transfer_registrations(_matching_old_methods, _matching_methods_length);
2938 }
2939
2940 // Deoptimize all compiled code that depends on this class.
2941 //
2942 // If the can_redefine_classes capability is obtained in the onload
2943 // phase then the compiler has recorded all dependencies from startup.
2944 // In that case we need only deoptimize and throw away all compiled code
2945 // that depends on the class.
2946 //
2947 // If can_redefine_classes is obtained sometime after the onload
2948 // phase then the dependency information may be incomplete. In that case
2949 // the first call to RedefineClasses causes all compiled code to be
2950 // thrown away. As can_redefine_classes has been obtained then
2951 // all future compilations will record dependencies so second and
2952 // subsequent calls to RedefineClasses need only throw away code
2953 // that depends on the class.
2954 //
2955 void VM_RedefineClasses::flush_dependent_code(instanceKlassHandle k_h, TRAPS) {
2956 assert_locked_or_safepoint(Compile_lock);
2957
2958 // All dependencies have been recorded from startup or this is a second or
2959 // subsequent use of RedefineClasses
2960 if (JvmtiExport::all_dependencies_are_recorded()) {
2961 Universe::flush_evol_dependents_on(k_h);
2962 } else {
2963 CodeCache::mark_all_nmethods_for_deoptimization();
2964
2965 ResourceMark rm(THREAD);
2966 DeoptimizationMarker dm;
2967
2968 // Deoptimize all activations depending on marked nmethods
2969 Deoptimization::deoptimize_dependents();
2970
2971 // Make the dependent methods not entrant (in VM_Deoptimize they are made zombies)
2972 CodeCache::make_marked_nmethods_not_entrant();
2973
2974 // From now on we know that the dependency information is complete
2975 JvmtiExport::set_all_dependencies_are_recorded(true);
2976 }
2977 }
2978
2979 void VM_RedefineClasses::compute_added_deleted_matching_methods() {
2980 methodOop old_method;
2981 methodOop new_method;
2982
2983 _matching_old_methods = NEW_RESOURCE_ARRAY(methodOop, _old_methods->length());
2984 _matching_new_methods = NEW_RESOURCE_ARRAY(methodOop, _old_methods->length());
2985 _added_methods = NEW_RESOURCE_ARRAY(methodOop, _new_methods->length());
2986 _deleted_methods = NEW_RESOURCE_ARRAY(methodOop, _old_methods->length());
2987
2988 _matching_methods_length = 0;
2989 _deleted_methods_length = 0;
2990 _added_methods_length = 0;
2991
2992 int nj = 0;
2993 int oj = 0;
2994 while (true) {
2995 if (oj >= _old_methods->length()) {
2996 if (nj >= _new_methods->length()) {
2997 break; // we've looked at everything, done
2998 }
2999 // New method at the end
3000 new_method = (methodOop) _new_methods->obj_at(nj);
3001 _added_methods[_added_methods_length++] = new_method;
3002 ++nj;
3003 } else if (nj >= _new_methods->length()) {
3004 // Old method, at the end, is deleted
3005 old_method = (methodOop) _old_methods->obj_at(oj);
3006 _deleted_methods[_deleted_methods_length++] = old_method;
3007 ++oj;
3008 } else {
3009 old_method = (methodOop) _old_methods->obj_at(oj);
3010 new_method = (methodOop) _new_methods->obj_at(nj);
3011 if (old_method->name() == new_method->name()) {
3012 if (old_method->signature() == new_method->signature()) {
3013 _matching_old_methods[_matching_methods_length ] = old_method;
3014 _matching_new_methods[_matching_methods_length++] = new_method;
3015 ++nj;
3016 ++oj;
3017 } else {
3018 // added overloaded have already been moved to the end,
3019 // so this is a deleted overloaded method
3020 _deleted_methods[_deleted_methods_length++] = old_method;
3021 ++oj;
3022 }
3023 } else { // names don't match
3024 if (old_method->name()->fast_compare(new_method->name()) > 0) {
3025 // new method
3026 _added_methods[_added_methods_length++] = new_method;
3027 ++nj;
3028 } else {
3029 // deleted method
3030 _deleted_methods[_deleted_methods_length++] = old_method;
3031 ++oj;
3032 }
3033 }
3034 }
3035 }
3036 assert(_matching_methods_length + _deleted_methods_length == _old_methods->length(), "sanity");
3037 assert(_matching_methods_length + _added_methods_length == _new_methods->length(), "sanity");
3038 }
3039
3040
3041
3042 // Install the redefinition of a class:
3043 // - house keeping (flushing breakpoints and caches, deoptimizing
3044 // dependent compiled code)
3045 // - replacing parts in the_class with parts from scratch_class
3046 // - adding a weak reference to track the obsolete but interesting
3047 // parts of the_class
3048 // - adjusting constant pool caches and vtables in other classes
3049 // that refer to methods in the_class. These adjustments use the
3050 // SystemDictionary::classes_do() facility which only allows
3051 // a helper method to be specified. The interesting parameters
3052 // that we would like to pass to the helper method are saved in
3053 // static global fields in the VM operation.
3054 void VM_RedefineClasses::redefine_single_class(jclass the_jclass,
3055 instanceKlassHandle scratch_class, TRAPS) {
3056
3057 RC_TIMER_START(_timer_rsc_phase1);
3058
3059 oop the_class_mirror = JNIHandles::resolve_non_null(the_jclass);
3060 klassOop the_class_oop = java_lang_Class::as_klassOop(the_class_mirror);
3061 instanceKlassHandle the_class = instanceKlassHandle(THREAD, the_class_oop);
3062
3063 #ifndef JVMTI_KERNEL
3064 // Remove all breakpoints in methods of this class
3065 JvmtiBreakpoints& jvmti_breakpoints = JvmtiCurrentBreakpoints::get_jvmti_breakpoints();
3066 jvmti_breakpoints.clearall_in_class_at_safepoint(the_class_oop);
3067 #endif // !JVMTI_KERNEL
3068
3069 if (the_class_oop == Universe::reflect_invoke_cache()->klass()) {
3070 // We are redefining java.lang.reflect.Method. Method.invoke() is
3071 // cached and users of the cache care about each active version of
3072 // the method so we have to track this previous version.
3073 // Do this before methods get switched
3074 Universe::reflect_invoke_cache()->add_previous_version(
3075 the_class->method_with_idnum(Universe::reflect_invoke_cache()->method_idnum()));
3076 }
3077
3078 // Deoptimize all compiled code that depends on this class
3079 flush_dependent_code(the_class, THREAD);
3080
3081 _old_methods = the_class->methods();
3082 _new_methods = scratch_class->methods();
3083 _the_class_oop = the_class_oop;
3084 compute_added_deleted_matching_methods();
3085 update_jmethod_ids();
3086
3087 // Attach new constant pool to the original klass. The original
3088 // klass still refers to the old constant pool (for now).
3089 scratch_class->constants()->set_pool_holder(the_class());
3090
3091 #if 0
3092 // In theory, with constant pool merging in place we should be able
3093 // to save space by using the new, merged constant pool in place of
3094 // the old constant pool(s). By "pool(s)" I mean the constant pool in
3095 // the klass version we are replacing now and any constant pool(s) in
3096 // previous versions of klass. Nice theory, doesn't work in practice.
3097 // When this code is enabled, even simple programs throw NullPointer
3098 // exceptions. I'm guessing that this is caused by some constant pool
3099 // cache difference between the new, merged constant pool and the
3100 // constant pool that was just being used by the klass. I'm keeping
3101 // this code around to archive the idea, but the code has to remain
3102 // disabled for now.
3103
3104 // Attach each old method to the new constant pool. This can be
3105 // done here since we are past the bytecode verification and
3106 // constant pool optimization phases.
3107 for (int i = _old_methods->length() - 1; i >= 0; i--) {
3108 methodOop method = (methodOop)_old_methods->obj_at(i);
3109 method->set_constants(scratch_class->constants());
3110 }
3111
3112 {
3113 // walk all previous versions of the klass
3114 instanceKlass *ik = (instanceKlass *)the_class()->klass_part();
3115 PreviousVersionWalker pvw(ik);
3116 instanceKlassHandle ikh;
3117 do {
3118 ikh = pvw.next_previous_version();
3119 if (!ikh.is_null()) {
3120 ik = ikh();
3121
3122 // attach previous version of klass to the new constant pool
3123 ik->set_constants(scratch_class->constants());
3124
3125 // Attach each method in the previous version of klass to the
3126 // new constant pool
3127 objArrayOop prev_methods = ik->methods();
3128 for (int i = prev_methods->length() - 1; i >= 0; i--) {
3129 methodOop method = (methodOop)prev_methods->obj_at(i);
3130 method->set_constants(scratch_class->constants());
3131 }
3132 }
3133 } while (!ikh.is_null());
3134 }
3135 #endif
3136
3137 // Replace methods and constantpool
3138 the_class->set_methods(_new_methods);
3139 scratch_class->set_methods(_old_methods); // To prevent potential GCing of the old methods,
3140 // and to be able to undo operation easily.
3141
3142 constantPoolOop old_constants = the_class->constants();
3143 the_class->set_constants(scratch_class->constants());
3144 scratch_class->set_constants(old_constants); // See the previous comment.
3145 #if 0
3146 // We are swapping the guts of "the new class" with the guts of "the
3147 // class". Since the old constant pool has just been attached to "the
3148 // new class", it seems logical to set the pool holder in the old
3149 // constant pool also. However, doing this will change the observable
3150 // class hierarchy for any old methods that are still executing. A
3151 // method can query the identity of its "holder" and this query uses
3152 // the method's constant pool link to find the holder. The change in
3153 // holding class from "the class" to "the new class" can confuse
3154 // things.
3155 //
3156 // Setting the old constant pool's holder will also cause
3157 // verification done during vtable initialization below to fail.
3158 // During vtable initialization, the vtable's class is verified to be
3159 // a subtype of the method's holder. The vtable's class is "the
3160 // class" and the method's holder is gotten from the constant pool
3161 // link in the method itself. For "the class"'s directly implemented
3162 // methods, the method holder is "the class" itself (as gotten from
3163 // the new constant pool). The check works fine in this case. The
3164 // check also works fine for methods inherited from super classes.
3165 //
3166 // Miranda methods are a little more complicated. A miranda method is
3167 // provided by an interface when the class implementing the interface
3168 // does not provide its own method. These interfaces are implemented
3169 // internally as an instanceKlass. These special instanceKlasses
3170 // share the constant pool of the class that "implements" the
3171 // interface. By sharing the constant pool, the method holder of a
3172 // miranda method is the class that "implements" the interface. In a
3173 // non-redefine situation, the subtype check works fine. However, if
3174 // the old constant pool's pool holder is modified, then the check
3175 // fails because there is no class hierarchy relationship between the
3176 // vtable's class and "the new class".
3177
3178 old_constants->set_pool_holder(scratch_class());
3179 #endif
3180
3181 // track which methods are EMCP for add_previous_version() call below
3182 BitMap emcp_methods(_old_methods->length());
3183 int emcp_method_count = 0;
3184 emcp_methods.clear(); // clears 0..(length() - 1)
3185 check_methods_and_mark_as_obsolete(&emcp_methods, &emcp_method_count);
3186 transfer_old_native_function_registrations(the_class);
3187
3188 // The class file bytes from before any retransformable agents mucked
3189 // with them was cached on the scratch class, move to the_class.
3190 // Note: we still want to do this if nothing needed caching since it
3191 // should get cleared in the_class too.
3192 if (the_class->get_cached_class_file_bytes() == 0) {
3193 // the_class doesn't have a cache yet so copy it
3194 the_class->set_cached_class_file(
3195 scratch_class->get_cached_class_file_bytes(),
3196 scratch_class->get_cached_class_file_len());
3197 }
3198 #ifndef PRODUCT
3199 else {
3200 assert(the_class->get_cached_class_file_bytes() ==
3201 scratch_class->get_cached_class_file_bytes(), "cache ptrs must match");
3202 assert(the_class->get_cached_class_file_len() ==
3203 scratch_class->get_cached_class_file_len(), "cache lens must match");
3204 }
3205 #endif
3206
3207 // Replace inner_classes
3208 typeArrayOop old_inner_classes = the_class->inner_classes();
3209 the_class->set_inner_classes(scratch_class->inner_classes());
3210 scratch_class->set_inner_classes(old_inner_classes);
3211
3212 // Initialize the vtable and interface table after
3213 // methods have been rewritten
3214 {
3215 ResourceMark rm(THREAD);
3216 // no exception should happen here since we explicitly
3217 // do not check loader constraints.
3218 // compare_and_normalize_class_versions has already checked:
3219 // - classloaders unchanged, signatures unchanged
3220 // - all instanceKlasses for redefined classes reused & contents updated
3221 the_class->vtable()->initialize_vtable(false, THREAD);
3222 the_class->itable()->initialize_itable(false, THREAD);
3223 assert(!HAS_PENDING_EXCEPTION || (THREAD->pending_exception()->is_a(SystemDictionary::ThreadDeath_klass())), "redefine exception");
3224 }
3225
3226 // Leave arrays of jmethodIDs and itable index cache unchanged
3227
3228 // Copy the "source file name" attribute from new class version
3229 the_class->set_source_file_name(scratch_class->source_file_name());
3230
3231 // Copy the "source debug extension" attribute from new class version
3232 the_class->set_source_debug_extension(
3233 scratch_class->source_debug_extension());
3234
3235 // Use of javac -g could be different in the old and the new
3236 if (scratch_class->access_flags().has_localvariable_table() !=
3237 the_class->access_flags().has_localvariable_table()) {
3238
3239 AccessFlags flags = the_class->access_flags();
3240 if (scratch_class->access_flags().has_localvariable_table()) {
3241 flags.set_has_localvariable_table();
3242 } else {
3243 flags.clear_has_localvariable_table();
3244 }
3245 the_class->set_access_flags(flags);
3246 }
3247
3248 // Replace class annotation fields values
3249 typeArrayOop old_class_annotations = the_class->class_annotations();
3250 the_class->set_class_annotations(scratch_class->class_annotations());
3251 scratch_class->set_class_annotations(old_class_annotations);
3252
3253 // Replace fields annotation fields values
3254 objArrayOop old_fields_annotations = the_class->fields_annotations();
3255 the_class->set_fields_annotations(scratch_class->fields_annotations());
3256 scratch_class->set_fields_annotations(old_fields_annotations);
3257
3258 // Replace methods annotation fields values
3259 objArrayOop old_methods_annotations = the_class->methods_annotations();
3260 the_class->set_methods_annotations(scratch_class->methods_annotations());
3261 scratch_class->set_methods_annotations(old_methods_annotations);
3262
3263 // Replace methods parameter annotation fields values
3264 objArrayOop old_methods_parameter_annotations =
3265 the_class->methods_parameter_annotations();
3266 the_class->set_methods_parameter_annotations(
3267 scratch_class->methods_parameter_annotations());
3268 scratch_class->set_methods_parameter_annotations(old_methods_parameter_annotations);
3269
3270 // Replace methods default annotation fields values
3271 objArrayOop old_methods_default_annotations =
3272 the_class->methods_default_annotations();
3273 the_class->set_methods_default_annotations(
3274 scratch_class->methods_default_annotations());
3275 scratch_class->set_methods_default_annotations(old_methods_default_annotations);
3276
3277 // Replace minor version number of class file
3278 u2 old_minor_version = the_class->minor_version();
3279 the_class->set_minor_version(scratch_class->minor_version());
3280 scratch_class->set_minor_version(old_minor_version);
3281
3282 // Replace major version number of class file
3283 u2 old_major_version = the_class->major_version();
3284 the_class->set_major_version(scratch_class->major_version());
3285 scratch_class->set_major_version(old_major_version);
3286
3287 // Replace CP indexes for class and name+type of enclosing method
3288 u2 old_class_idx = the_class->enclosing_method_class_index();
3289 u2 old_method_idx = the_class->enclosing_method_method_index();
3290 the_class->set_enclosing_method_indices(
3291 scratch_class->enclosing_method_class_index(),
3292 scratch_class->enclosing_method_method_index());
3293 scratch_class->set_enclosing_method_indices(old_class_idx, old_method_idx);
3294
3295 // keep track of previous versions of this class
3296 the_class->add_previous_version(scratch_class, &emcp_methods,
3297 emcp_method_count);
3298
3299 RC_TIMER_STOP(_timer_rsc_phase1);
3300 RC_TIMER_START(_timer_rsc_phase2);
3301
3302 // Adjust constantpool caches and vtables for all classes
3303 // that reference methods of the evolved class.
3304 SystemDictionary::classes_do(adjust_cpool_cache_and_vtable, THREAD);
3305
3306 if (the_class->oop_map_cache() != NULL) {
3307 // Flush references to any obsolete methods from the oop map cache
3308 // so that obsolete methods are not pinned.
3309 the_class->oop_map_cache()->flush_obsolete_entries();
3310 }
3311
3312 // increment the classRedefinedCount field in the_class and in any
3313 // direct and indirect subclasses of the_class
3314 increment_class_counter((instanceKlass *)the_class()->klass_part(), THREAD);
3315
3316 // RC_TRACE macro has an embedded ResourceMark
3317 RC_TRACE_WITH_THREAD(0x00000001, THREAD,
3318 ("redefined name=%s, count=%d (avail_mem=" UINT64_FORMAT "K)",
3319 the_class->external_name(),
3320 java_lang_Class::classRedefinedCount(the_class_mirror),
3321 os::available_memory() >> 10));
3322
3323 RC_TIMER_STOP(_timer_rsc_phase2);
3324 } // end redefine_single_class()
3325
3326
3327 // Increment the classRedefinedCount field in the specific instanceKlass
3328 // and in all direct and indirect subclasses.
3329 void VM_RedefineClasses::increment_class_counter(instanceKlass *ik, TRAPS) {
3330 oop class_mirror = ik->java_mirror();
3331 klassOop class_oop = java_lang_Class::as_klassOop(class_mirror);
3332 int new_count = java_lang_Class::classRedefinedCount(class_mirror) + 1;
3333 java_lang_Class::set_classRedefinedCount(class_mirror, new_count);
3334
3335 if (class_oop != _the_class_oop) {
3336 // _the_class_oop count is printed at end of redefine_single_class()
3337 RC_TRACE_WITH_THREAD(0x00000008, THREAD,
3338 ("updated count in subclass=%s to %d", ik->external_name(), new_count));
3339 }
3340
3341 for (Klass *subk = ik->subklass(); subk != NULL;
3342 subk = subk->next_sibling()) {
3343 if (subk->oop_is_instance()) {
3344 // Only update instanceKlasses
3345 instanceKlass *subik = (instanceKlass*)subk;
3346 // recursively do subclasses of the current subclass
3347 increment_class_counter(subik, THREAD);
3348 }
3349 }
3350 }
3351
3352 #ifndef PRODUCT
3353 void VM_RedefineClasses::check_class(klassOop k_oop,
3354 oop initiating_loader, TRAPS) {
3355 Klass *k = k_oop->klass_part();
3356 if (k->oop_is_instance()) {
3357 HandleMark hm(THREAD);
3358 instanceKlass *ik = (instanceKlass *) k;
3359
3360 if (ik->vtable_length() > 0) {
3361 ResourceMark rm(THREAD);
3362 if (!ik->vtable()->check_no_old_entries()) {
3363 tty->print_cr("klassVtable::check_no_old_entries failure -- OLD method found -- class: %s", ik->signature_name());
3364 ik->vtable()->dump_vtable();
3365 dump_methods();
3366 assert(false, "OLD method found");
3367 }
3368 }
3369 }
3370 }
3371
3372 void VM_RedefineClasses::dump_methods() {
3373 int j;
3374 tty->print_cr("_old_methods --");
3375 for (j = 0; j < _old_methods->length(); ++j) {
3376 methodOop m = (methodOop) _old_methods->obj_at(j);
3377 tty->print("%4d (%5d) ", j, m->vtable_index());
3378 m->access_flags().print_on(tty);
3379 tty->print(" -- ");
3380 m->print_name(tty);
3381 tty->cr();
3382 }
3383 tty->print_cr("_new_methods --");
3384 for (j = 0; j < _new_methods->length(); ++j) {
3385 methodOop m = (methodOop) _new_methods->obj_at(j);
3386 tty->print("%4d (%5d) ", j, m->vtable_index());
3387 m->access_flags().print_on(tty);
3388 tty->print(" -- ");
3389 m->print_name(tty);
3390 tty->cr();
3391 }
3392 tty->print_cr("_matching_(old/new)_methods --");
3393 for (j = 0; j < _matching_methods_length; ++j) {
3394 methodOop m = _matching_old_methods[j];
3395 tty->print("%4d (%5d) ", j, m->vtable_index());
3396 m->access_flags().print_on(tty);
3397 tty->print(" -- ");
3398 m->print_name(tty);
3399 tty->cr();
3400 m = _matching_new_methods[j];
3401 tty->print(" (%5d) ", m->vtable_index());
3402 m->access_flags().print_on(tty);
3403 tty->cr();
3404 }
3405 tty->print_cr("_deleted_methods --");
3406 for (j = 0; j < _deleted_methods_length; ++j) {
3407 methodOop m = _deleted_methods[j];
3408 tty->print("%4d (%5d) ", j, m->vtable_index());
3409 m->access_flags().print_on(tty);
3410 tty->print(" -- ");
3411 m->print_name(tty);
3412 tty->cr();
3413 }
3414 tty->print_cr("_added_methods --");
3415 for (j = 0; j < _added_methods_length; ++j) {
3416 methodOop m = _added_methods[j];
3417 tty->print("%4d (%5d) ", j, m->vtable_index());
3418 m->access_flags().print_on(tty);
3419 tty->print(" -- ");
3420 m->print_name(tty);
3421 tty->cr();
3422 }
3423 }
3424 #endif