1 /*
2 * Copyright (c) 2003, 2011, 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 (avail_mem=" UINT64_FORMAT "K)",
858 the_class->external_name(), os::available_memory() >> 10));
859
860 ClassFileStream st((u1*) _class_defs[i].class_bytes,
861 _class_defs[i].class_byte_count, (char *)"__VM_RedefineClasses__");
862
863 // Parse the stream.
864 Handle the_class_loader(THREAD, the_class->class_loader());
865 Handle protection_domain(THREAD, the_class->protection_domain());
866 // Set redefined class handle in JvmtiThreadState class.
867 // This redefined class is sent to agent event handler for class file
868 // load hook event.
869 state->set_class_being_redefined(&the_class, _class_load_kind);
870
871 klassOop k = SystemDictionary::parse_stream(the_class_sym,
872 the_class_loader,
873 protection_domain,
874 &st,
875 THREAD);
876 // Clear class_being_redefined just to be sure.
877 state->clear_class_being_redefined();
878
879 // TODO: if this is retransform, and nothing changed we can skip it
880
881 instanceKlassHandle scratch_class (THREAD, k);
882
883 if (HAS_PENDING_EXCEPTION) {
884 Symbol* ex_name = PENDING_EXCEPTION->klass()->klass_part()->name();
885 // RC_TRACE_WITH_THREAD macro has an embedded ResourceMark
886 RC_TRACE_WITH_THREAD(0x00000002, THREAD, ("parse_stream exception: '%s'",
887 ex_name->as_C_string()));
888 CLEAR_PENDING_EXCEPTION;
889
890 if (ex_name == vmSymbols::java_lang_UnsupportedClassVersionError()) {
891 return JVMTI_ERROR_UNSUPPORTED_VERSION;
892 } else if (ex_name == vmSymbols::java_lang_ClassFormatError()) {
893 return JVMTI_ERROR_INVALID_CLASS_FORMAT;
894 } else if (ex_name == vmSymbols::java_lang_ClassCircularityError()) {
895 return JVMTI_ERROR_CIRCULAR_CLASS_DEFINITION;
896 } else if (ex_name == vmSymbols::java_lang_NoClassDefFoundError()) {
897 // The message will be "XXX (wrong name: YYY)"
898 return JVMTI_ERROR_NAMES_DONT_MATCH;
899 } else if (ex_name == vmSymbols::java_lang_OutOfMemoryError()) {
900 return JVMTI_ERROR_OUT_OF_MEMORY;
901 } else { // Just in case more exceptions can be thrown..
902 return JVMTI_ERROR_FAILS_VERIFICATION;
903 }
904 }
905
906 // Ensure class is linked before redefine
907 if (!the_class->is_linked()) {
908 the_class->link_class(THREAD);
909 if (HAS_PENDING_EXCEPTION) {
910 Symbol* ex_name = PENDING_EXCEPTION->klass()->klass_part()->name();
911 // RC_TRACE_WITH_THREAD macro has an embedded ResourceMark
912 RC_TRACE_WITH_THREAD(0x00000002, THREAD, ("link_class exception: '%s'",
913 ex_name->as_C_string()));
914 CLEAR_PENDING_EXCEPTION;
915 if (ex_name == vmSymbols::java_lang_OutOfMemoryError()) {
916 return JVMTI_ERROR_OUT_OF_MEMORY;
917 } else {
918 return JVMTI_ERROR_INTERNAL;
919 }
920 }
921 }
922
923 // Do the validity checks in compare_and_normalize_class_versions()
924 // before verifying the byte codes. By doing these checks first, we
925 // limit the number of functions that require redirection from
926 // the_class to scratch_class. In particular, we don't have to
927 // modify JNI GetSuperclass() and thus won't change its performance.
928 jvmtiError res = compare_and_normalize_class_versions(the_class,
929 scratch_class);
930 if (res != JVMTI_ERROR_NONE) {
931 return res;
932 }
933
934 // verify what the caller passed us
935 {
936 // The bug 6214132 caused the verification to fail.
937 // Information about the_class and scratch_class is temporarily
938 // recorded into jvmtiThreadState. This data is used to redirect
939 // the_class to scratch_class in the JVM_* functions called by the
940 // verifier. Please, refer to jvmtiThreadState.hpp for the detailed
941 // description.
942 RedefineVerifyMark rvm(&the_class, &scratch_class, state);
943 Verifier::verify(
944 scratch_class, Verifier::ThrowException, true, THREAD);
945 }
946
947 if (HAS_PENDING_EXCEPTION) {
948 Symbol* ex_name = PENDING_EXCEPTION->klass()->klass_part()->name();
949 // RC_TRACE_WITH_THREAD macro has an embedded ResourceMark
950 RC_TRACE_WITH_THREAD(0x00000002, THREAD,
951 ("verify_byte_codes exception: '%s'", ex_name->as_C_string()));
952 CLEAR_PENDING_EXCEPTION;
953 if (ex_name == vmSymbols::java_lang_OutOfMemoryError()) {
954 return JVMTI_ERROR_OUT_OF_MEMORY;
955 } else {
956 // tell the caller the bytecodes are bad
957 return JVMTI_ERROR_FAILS_VERIFICATION;
958 }
959 }
960
961 res = merge_cp_and_rewrite(the_class, scratch_class, THREAD);
962 if (res != JVMTI_ERROR_NONE) {
963 return res;
964 }
965
966 if (VerifyMergedCPBytecodes) {
967 // verify what we have done during constant pool merging
968 {
969 RedefineVerifyMark rvm(&the_class, &scratch_class, state);
970 Verifier::verify(scratch_class, Verifier::ThrowException, true, THREAD);
971 }
972
973 if (HAS_PENDING_EXCEPTION) {
974 Symbol* ex_name = PENDING_EXCEPTION->klass()->klass_part()->name();
975 // RC_TRACE_WITH_THREAD macro has an embedded ResourceMark
976 RC_TRACE_WITH_THREAD(0x00000002, THREAD,
977 ("verify_byte_codes post merge-CP exception: '%s'",
978 ex_name->as_C_string()));
979 CLEAR_PENDING_EXCEPTION;
980 if (ex_name == vmSymbols::java_lang_OutOfMemoryError()) {
981 return JVMTI_ERROR_OUT_OF_MEMORY;
982 } else {
983 // tell the caller that constant pool merging screwed up
984 return JVMTI_ERROR_INTERNAL;
985 }
986 }
987 }
988
989 Rewriter::rewrite(scratch_class, THREAD);
990 if (!HAS_PENDING_EXCEPTION) {
991 Rewriter::relocate_and_link(scratch_class, THREAD);
992 }
993 if (HAS_PENDING_EXCEPTION) {
994 Symbol* ex_name = PENDING_EXCEPTION->klass()->klass_part()->name();
995 CLEAR_PENDING_EXCEPTION;
996 if (ex_name == vmSymbols::java_lang_OutOfMemoryError()) {
997 return JVMTI_ERROR_OUT_OF_MEMORY;
998 } else {
999 return JVMTI_ERROR_INTERNAL;
1000 }
1001 }
1002
1003 _scratch_classes[i] = scratch_class;
1004
1005 // RC_TRACE_WITH_THREAD macro has an embedded ResourceMark
1006 RC_TRACE_WITH_THREAD(0x00000001, THREAD,
1007 ("loaded name=%s (avail_mem=" UINT64_FORMAT "K)",
1008 the_class->external_name(), os::available_memory() >> 10));
1009 }
1010
1011 return JVMTI_ERROR_NONE;
1012 }
1013
1014
1015 // Map old_index to new_index as needed. scratch_cp is only needed
1016 // for RC_TRACE() calls.
1017 void VM_RedefineClasses::map_index(constantPoolHandle scratch_cp,
1018 int old_index, int new_index) {
1019 if (find_new_index(old_index) != 0) {
1020 // old_index is already mapped
1021 return;
1022 }
1023
1024 if (old_index == new_index) {
1025 // no mapping is needed
1026 return;
1027 }
1028
1029 _index_map_p->at_put(old_index, new_index);
1030 _index_map_count++;
1031
1032 RC_TRACE(0x00040000, ("mapped tag %d at index %d to %d",
1033 scratch_cp->tag_at(old_index).value(), old_index, new_index));
1034 } // end map_index()
1035
1036
1037 // Merge old_cp and scratch_cp and return the results of the merge via
1038 // merge_cp_p. The number of entries in *merge_cp_p is returned via
1039 // merge_cp_length_p. The entries in old_cp occupy the same locations
1040 // in *merge_cp_p. Also creates a map of indices from entries in
1041 // scratch_cp to the corresponding entry in *merge_cp_p. Index map
1042 // entries are only created for entries in scratch_cp that occupy a
1043 // different location in *merged_cp_p.
1044 bool VM_RedefineClasses::merge_constant_pools(constantPoolHandle old_cp,
1045 constantPoolHandle scratch_cp, constantPoolHandle *merge_cp_p,
1046 int *merge_cp_length_p, TRAPS) {
1047
1048 if (merge_cp_p == NULL) {
1049 assert(false, "caller must provide scatch constantPool");
1050 return false; // robustness
1051 }
1052 if (merge_cp_length_p == NULL) {
1053 assert(false, "caller must provide scatch CP length");
1054 return false; // robustness
1055 }
1056 // Worst case we need old_cp->length() + scratch_cp()->length(),
1057 // but the caller might be smart so make sure we have at least
1058 // the minimum.
1059 if ((*merge_cp_p)->length() < old_cp->length()) {
1060 assert(false, "merge area too small");
1061 return false; // robustness
1062 }
1063
1064 RC_TRACE_WITH_THREAD(0x00010000, THREAD,
1065 ("old_cp_len=%d, scratch_cp_len=%d", old_cp->length(),
1066 scratch_cp->length()));
1067
1068 {
1069 // Pass 0:
1070 // The old_cp is copied to *merge_cp_p; this means that any code
1071 // using old_cp does not have to change. This work looks like a
1072 // perfect fit for constantPoolOop::copy_cp_to(), but we need to
1073 // handle one special case:
1074 // - revert JVM_CONSTANT_Class to JVM_CONSTANT_UnresolvedClass
1075 // This will make verification happy.
1076
1077 int old_i; // index into old_cp
1078
1079 // index zero (0) is not used in constantPools
1080 for (old_i = 1; old_i < old_cp->length(); old_i++) {
1081 // leave debugging crumb
1082 jbyte old_tag = old_cp->tag_at(old_i).value();
1083 switch (old_tag) {
1084 case JVM_CONSTANT_Class:
1085 case JVM_CONSTANT_UnresolvedClass:
1086 // revert the copy to JVM_CONSTANT_UnresolvedClass
1087 // May be resolving while calling this so do the same for
1088 // JVM_CONSTANT_UnresolvedClass (klass_name_at() deals with transition)
1089 (*merge_cp_p)->unresolved_klass_at_put(old_i,
1090 old_cp->klass_name_at(old_i));
1091 break;
1092
1093 case JVM_CONSTANT_Double:
1094 case JVM_CONSTANT_Long:
1095 // just copy the entry to *merge_cp_p, but double and long take
1096 // two constant pool entries
1097 constantPoolOopDesc::copy_entry_to(old_cp, old_i, *merge_cp_p, old_i, CHECK_0);
1098 old_i++;
1099 break;
1100
1101 default:
1102 // just copy the entry to *merge_cp_p
1103 constantPoolOopDesc::copy_entry_to(old_cp, old_i, *merge_cp_p, old_i, CHECK_0);
1104 break;
1105 }
1106 } // end for each old_cp entry
1107
1108 // We don't need to sanity check that *merge_cp_length_p is within
1109 // *merge_cp_p bounds since we have the minimum on-entry check above.
1110 (*merge_cp_length_p) = old_i;
1111 }
1112
1113 // merge_cp_len should be the same as old_cp->length() at this point
1114 // so this trace message is really a "warm-and-breathing" message.
1115 RC_TRACE_WITH_THREAD(0x00020000, THREAD,
1116 ("after pass 0: merge_cp_len=%d", *merge_cp_length_p));
1117
1118 int scratch_i; // index into scratch_cp
1119 {
1120 // Pass 1a:
1121 // Compare scratch_cp entries to the old_cp entries that we have
1122 // already copied to *merge_cp_p. In this pass, we are eliminating
1123 // exact duplicates (matching entry at same index) so we only
1124 // compare entries in the common indice range.
1125 int increment = 1;
1126 int pass1a_length = MIN2(old_cp->length(), scratch_cp->length());
1127 for (scratch_i = 1; scratch_i < pass1a_length; scratch_i += increment) {
1128 switch (scratch_cp->tag_at(scratch_i).value()) {
1129 case JVM_CONSTANT_Double:
1130 case JVM_CONSTANT_Long:
1131 // double and long take two constant pool entries
1132 increment = 2;
1133 break;
1134
1135 default:
1136 increment = 1;
1137 break;
1138 }
1139
1140 bool match = scratch_cp->compare_entry_to(scratch_i, *merge_cp_p,
1141 scratch_i, CHECK_0);
1142 if (match) {
1143 // found a match at the same index so nothing more to do
1144 continue;
1145 } else if (is_unresolved_class_mismatch(scratch_cp, scratch_i,
1146 *merge_cp_p, scratch_i)) {
1147 // The mismatch in compare_entry_to() above is because of a
1148 // resolved versus unresolved class entry at the same index
1149 // with the same string value. Since Pass 0 reverted any
1150 // class entries to unresolved class entries in *merge_cp_p,
1151 // we go with the unresolved class entry.
1152 continue;
1153 } else if (is_unresolved_string_mismatch(scratch_cp, scratch_i,
1154 *merge_cp_p, scratch_i)) {
1155 // The mismatch in compare_entry_to() above is because of a
1156 // resolved versus unresolved string entry at the same index
1157 // with the same string value. We can live with whichever
1158 // happens to be at scratch_i in *merge_cp_p.
1159 continue;
1160 }
1161
1162 int found_i = scratch_cp->find_matching_entry(scratch_i, *merge_cp_p,
1163 CHECK_0);
1164 if (found_i != 0) {
1165 guarantee(found_i != scratch_i,
1166 "compare_entry_to() and find_matching_entry() do not agree");
1167
1168 // Found a matching entry somewhere else in *merge_cp_p so
1169 // just need a mapping entry.
1170 map_index(scratch_cp, scratch_i, found_i);
1171 continue;
1172 }
1173
1174 // The find_matching_entry() call above could fail to find a match
1175 // due to a resolved versus unresolved class or string entry situation
1176 // like we solved above with the is_unresolved_*_mismatch() calls.
1177 // However, we would have to call is_unresolved_*_mismatch() over
1178 // all of *merge_cp_p (potentially) and that doesn't seem to be
1179 // worth the time.
1180
1181 // No match found so we have to append this entry and any unique
1182 // referenced entries to *merge_cp_p.
1183 append_entry(scratch_cp, scratch_i, merge_cp_p, merge_cp_length_p,
1184 CHECK_0);
1185 }
1186 }
1187
1188 RC_TRACE_WITH_THREAD(0x00020000, THREAD,
1189 ("after pass 1a: merge_cp_len=%d, scratch_i=%d, index_map_len=%d",
1190 *merge_cp_length_p, scratch_i, _index_map_count));
1191
1192 if (scratch_i < scratch_cp->length()) {
1193 // Pass 1b:
1194 // old_cp is smaller than scratch_cp so there are entries in
1195 // scratch_cp that we have not yet processed. We take care of
1196 // those now.
1197 int increment = 1;
1198 for (; scratch_i < scratch_cp->length(); scratch_i += increment) {
1199 switch (scratch_cp->tag_at(scratch_i).value()) {
1200 case JVM_CONSTANT_Double:
1201 case JVM_CONSTANT_Long:
1202 // double and long take two constant pool entries
1203 increment = 2;
1204 break;
1205
1206 default:
1207 increment = 1;
1208 break;
1209 }
1210
1211 int found_i =
1212 scratch_cp->find_matching_entry(scratch_i, *merge_cp_p, CHECK_0);
1213 if (found_i != 0) {
1214 // Found a matching entry somewhere else in *merge_cp_p so
1215 // just need a mapping entry.
1216 map_index(scratch_cp, scratch_i, found_i);
1217 continue;
1218 }
1219
1220 // No match found so we have to append this entry and any unique
1221 // referenced entries to *merge_cp_p.
1222 append_entry(scratch_cp, scratch_i, merge_cp_p, merge_cp_length_p,
1223 CHECK_0);
1224 }
1225
1226 RC_TRACE_WITH_THREAD(0x00020000, THREAD,
1227 ("after pass 1b: merge_cp_len=%d, scratch_i=%d, index_map_len=%d",
1228 *merge_cp_length_p, scratch_i, _index_map_count));
1229 }
1230
1231 return true;
1232 } // end merge_constant_pools()
1233
1234
1235 // Merge constant pools between the_class and scratch_class and
1236 // potentially rewrite bytecodes in scratch_class to use the merged
1237 // constant pool.
1238 jvmtiError VM_RedefineClasses::merge_cp_and_rewrite(
1239 instanceKlassHandle the_class, instanceKlassHandle scratch_class,
1240 TRAPS) {
1241 // worst case merged constant pool length is old and new combined
1242 int merge_cp_length = the_class->constants()->length()
1243 + scratch_class->constants()->length();
1244
1245 constantPoolHandle old_cp(THREAD, the_class->constants());
1246 constantPoolHandle scratch_cp(THREAD, scratch_class->constants());
1247
1248 // Constant pools are not easily reused so we allocate a new one
1249 // each time.
1250 // merge_cp is created unsafe for concurrent GC processing. It
1251 // should be marked safe before discarding it. Even though
1252 // garbage, if it crosses a card boundary, it may be scanned
1253 // in order to find the start of the first complete object on the card.
1254 constantPoolHandle merge_cp(THREAD,
1255 oopFactory::new_constantPool(merge_cp_length,
1256 oopDesc::IsUnsafeConc,
1257 THREAD));
1258 int orig_length = old_cp->orig_length();
1259 if (orig_length == 0) {
1260 // This old_cp is an actual original constant pool. We save
1261 // the original length in the merged constant pool so that
1262 // merge_constant_pools() can be more efficient. If a constant
1263 // pool has a non-zero orig_length() value, then that constant
1264 // pool was created by a merge operation in RedefineClasses.
1265 merge_cp->set_orig_length(old_cp->length());
1266 } else {
1267 // This old_cp is a merged constant pool from a previous
1268 // RedefineClasses() calls so just copy the orig_length()
1269 // value.
1270 merge_cp->set_orig_length(old_cp->orig_length());
1271 }
1272
1273 ResourceMark rm(THREAD);
1274 _index_map_count = 0;
1275 _index_map_p = new intArray(scratch_cp->length(), -1);
1276
1277 bool result = merge_constant_pools(old_cp, scratch_cp, &merge_cp,
1278 &merge_cp_length, THREAD);
1279 if (!result) {
1280 // The merge can fail due to memory allocation failure or due
1281 // to robustness checks.
1282 return JVMTI_ERROR_INTERNAL;
1283 }
1284
1285 RC_TRACE_WITH_THREAD(0x00010000, THREAD,
1286 ("merge_cp_len=%d, index_map_len=%d", merge_cp_length, _index_map_count));
1287
1288 if (_index_map_count == 0) {
1289 // there is nothing to map between the new and merged constant pools
1290
1291 if (old_cp->length() == scratch_cp->length()) {
1292 // The old and new constant pools are the same length and the
1293 // index map is empty. This means that the three constant pools
1294 // are equivalent (but not the same). Unfortunately, the new
1295 // constant pool has not gone through link resolution nor have
1296 // the new class bytecodes gone through constant pool cache
1297 // rewriting so we can't use the old constant pool with the new
1298 // class.
1299
1300 merge_cp()->set_is_conc_safe(true);
1301 merge_cp = constantPoolHandle(); // toss the merged constant pool
1302 } else if (old_cp->length() < scratch_cp->length()) {
1303 // The old constant pool has fewer entries than the new constant
1304 // pool and the index map is empty. This means the new constant
1305 // pool is a superset of the old constant pool. However, the old
1306 // class bytecodes have already gone through constant pool cache
1307 // rewriting so we can't use the new constant pool with the old
1308 // class.
1309
1310 merge_cp()->set_is_conc_safe(true);
1311 merge_cp = constantPoolHandle(); // toss the merged constant pool
1312 } else {
1313 // The old constant pool has more entries than the new constant
1314 // pool and the index map is empty. This means that both the old
1315 // and merged constant pools are supersets of the new constant
1316 // pool.
1317
1318 // Replace the new constant pool with a shrunken copy of the
1319 // merged constant pool; the previous new constant pool will
1320 // get GCed.
1321 set_new_constant_pool(scratch_class, merge_cp, merge_cp_length, true,
1322 THREAD);
1323 // drop local ref to the merged constant pool
1324 merge_cp()->set_is_conc_safe(true);
1325 merge_cp = constantPoolHandle();
1326 }
1327 } else {
1328 if (RC_TRACE_ENABLED(0x00040000)) {
1329 // don't want to loop unless we are tracing
1330 int count = 0;
1331 for (int i = 1; i < _index_map_p->length(); i++) {
1332 int value = _index_map_p->at(i);
1333
1334 if (value != -1) {
1335 RC_TRACE_WITH_THREAD(0x00040000, THREAD,
1336 ("index_map[%d]: old=%d new=%d", count, i, value));
1337 count++;
1338 }
1339 }
1340 }
1341
1342 // We have entries mapped between the new and merged constant pools
1343 // so we have to rewrite some constant pool references.
1344 if (!rewrite_cp_refs(scratch_class, THREAD)) {
1345 return JVMTI_ERROR_INTERNAL;
1346 }
1347
1348 // Replace the new constant pool with a shrunken copy of the
1349 // merged constant pool so now the rewritten bytecodes have
1350 // valid references; the previous new constant pool will get
1351 // GCed.
1352 set_new_constant_pool(scratch_class, merge_cp, merge_cp_length, true,
1353 THREAD);
1354 merge_cp()->set_is_conc_safe(true);
1355 }
1356 assert(old_cp()->is_conc_safe(), "Just checking");
1357 assert(scratch_cp()->is_conc_safe(), "Just checking");
1358
1359 return JVMTI_ERROR_NONE;
1360 } // end merge_cp_and_rewrite()
1361
1362
1363 // Rewrite constant pool references in klass scratch_class.
1364 bool VM_RedefineClasses::rewrite_cp_refs(instanceKlassHandle scratch_class,
1365 TRAPS) {
1366
1367 // rewrite constant pool references in the methods:
1368 if (!rewrite_cp_refs_in_methods(scratch_class, THREAD)) {
1369 // propagate failure back to caller
1370 return false;
1371 }
1372
1373 // rewrite constant pool references in the class_annotations:
1374 if (!rewrite_cp_refs_in_class_annotations(scratch_class, THREAD)) {
1375 // propagate failure back to caller
1376 return false;
1377 }
1378
1379 // rewrite constant pool references in the fields_annotations:
1380 if (!rewrite_cp_refs_in_fields_annotations(scratch_class, THREAD)) {
1381 // propagate failure back to caller
1382 return false;
1383 }
1384
1385 // rewrite constant pool references in the methods_annotations:
1386 if (!rewrite_cp_refs_in_methods_annotations(scratch_class, THREAD)) {
1387 // propagate failure back to caller
1388 return false;
1389 }
1390
1391 // rewrite constant pool references in the methods_parameter_annotations:
1392 if (!rewrite_cp_refs_in_methods_parameter_annotations(scratch_class,
1393 THREAD)) {
1394 // propagate failure back to caller
1395 return false;
1396 }
1397
1398 // rewrite constant pool references in the methods_default_annotations:
1399 if (!rewrite_cp_refs_in_methods_default_annotations(scratch_class,
1400 THREAD)) {
1401 // propagate failure back to caller
1402 return false;
1403 }
1404
1405 return true;
1406 } // end rewrite_cp_refs()
1407
1408
1409 // Rewrite constant pool references in the methods.
1410 bool VM_RedefineClasses::rewrite_cp_refs_in_methods(
1411 instanceKlassHandle scratch_class, TRAPS) {
1412
1413 objArrayHandle methods(THREAD, scratch_class->methods());
1414
1415 if (methods.is_null() || methods->length() == 0) {
1416 // no methods so nothing to do
1417 return true;
1418 }
1419
1420 // rewrite constant pool references in the methods:
1421 for (int i = methods->length() - 1; i >= 0; i--) {
1422 methodHandle method(THREAD, (methodOop)methods->obj_at(i));
1423 methodHandle new_method;
1424 rewrite_cp_refs_in_method(method, &new_method, CHECK_false);
1425 if (!new_method.is_null()) {
1426 // the method has been replaced so save the new method version
1427 methods->obj_at_put(i, new_method());
1428 }
1429 }
1430
1431 return true;
1432 }
1433
1434
1435 // Rewrite constant pool references in the specific method. This code
1436 // was adapted from Rewriter::rewrite_method().
1437 void VM_RedefineClasses::rewrite_cp_refs_in_method(methodHandle method,
1438 methodHandle *new_method_p, TRAPS) {
1439
1440 *new_method_p = methodHandle(); // default is no new method
1441
1442 // We cache a pointer to the bytecodes here in code_base. If GC
1443 // moves the methodOop, then the bytecodes will also move which
1444 // will likely cause a crash. We create a No_Safepoint_Verifier
1445 // object to detect whether we pass a possible safepoint in this
1446 // code block.
1447 No_Safepoint_Verifier nsv;
1448
1449 // Bytecodes and their length
1450 address code_base = method->code_base();
1451 int code_length = method->code_size();
1452
1453 int bc_length;
1454 for (int bci = 0; bci < code_length; bci += bc_length) {
1455 address bcp = code_base + bci;
1456 Bytecodes::Code c = (Bytecodes::Code)(*bcp);
1457
1458 bc_length = Bytecodes::length_for(c);
1459 if (bc_length == 0) {
1460 // More complicated bytecodes report a length of zero so
1461 // we have to try again a slightly different way.
1462 bc_length = Bytecodes::length_at(method(), bcp);
1463 }
1464
1465 assert(bc_length != 0, "impossible bytecode length");
1466
1467 switch (c) {
1468 case Bytecodes::_ldc:
1469 {
1470 int cp_index = *(bcp + 1);
1471 int new_index = find_new_index(cp_index);
1472
1473 if (StressLdcRewrite && new_index == 0) {
1474 // If we are stressing ldc -> ldc_w rewriting, then we
1475 // always need a new_index value.
1476 new_index = cp_index;
1477 }
1478 if (new_index != 0) {
1479 // the original index is mapped so we have more work to do
1480 if (!StressLdcRewrite && new_index <= max_jubyte) {
1481 // The new value can still use ldc instead of ldc_w
1482 // unless we are trying to stress ldc -> ldc_w rewriting
1483 RC_TRACE_WITH_THREAD(0x00080000, THREAD,
1484 ("%s@" INTPTR_FORMAT " old=%d, new=%d", Bytecodes::name(c),
1485 bcp, cp_index, new_index));
1486 *(bcp + 1) = new_index;
1487 } else {
1488 RC_TRACE_WITH_THREAD(0x00080000, THREAD,
1489 ("%s->ldc_w@" INTPTR_FORMAT " old=%d, new=%d",
1490 Bytecodes::name(c), bcp, cp_index, new_index));
1491 // the new value needs ldc_w instead of ldc
1492 u_char inst_buffer[4]; // max instruction size is 4 bytes
1493 bcp = (address)inst_buffer;
1494 // construct new instruction sequence
1495 *bcp = Bytecodes::_ldc_w;
1496 bcp++;
1497 // Rewriter::rewrite_method() does not rewrite ldc -> ldc_w.
1498 // See comment below for difference between put_Java_u2()
1499 // and put_native_u2().
1500 Bytes::put_Java_u2(bcp, new_index);
1501
1502 Relocator rc(method, NULL /* no RelocatorListener needed */);
1503 methodHandle m;
1504 {
1505 Pause_No_Safepoint_Verifier pnsv(&nsv);
1506
1507 // ldc is 2 bytes and ldc_w is 3 bytes
1508 m = rc.insert_space_at(bci, 3, inst_buffer, THREAD);
1509 if (m.is_null() || HAS_PENDING_EXCEPTION) {
1510 guarantee(false, "insert_space_at() failed");
1511 }
1512 }
1513
1514 // return the new method so that the caller can update
1515 // the containing class
1516 *new_method_p = method = m;
1517 // switch our bytecode processing loop from the old method
1518 // to the new method
1519 code_base = method->code_base();
1520 code_length = method->code_size();
1521 bcp = code_base + bci;
1522 c = (Bytecodes::Code)(*bcp);
1523 bc_length = Bytecodes::length_for(c);
1524 assert(bc_length != 0, "sanity check");
1525 } // end we need ldc_w instead of ldc
1526 } // end if there is a mapped index
1527 } break;
1528
1529 // these bytecodes have a two-byte constant pool index
1530 case Bytecodes::_anewarray : // fall through
1531 case Bytecodes::_checkcast : // fall through
1532 case Bytecodes::_getfield : // fall through
1533 case Bytecodes::_getstatic : // fall through
1534 case Bytecodes::_instanceof : // fall through
1535 case Bytecodes::_invokeinterface: // fall through
1536 case Bytecodes::_invokespecial : // fall through
1537 case Bytecodes::_invokestatic : // fall through
1538 case Bytecodes::_invokevirtual : // fall through
1539 case Bytecodes::_ldc_w : // fall through
1540 case Bytecodes::_ldc2_w : // fall through
1541 case Bytecodes::_multianewarray : // fall through
1542 case Bytecodes::_new : // fall through
1543 case Bytecodes::_putfield : // fall through
1544 case Bytecodes::_putstatic :
1545 {
1546 address p = bcp + 1;
1547 int cp_index = Bytes::get_Java_u2(p);
1548 int new_index = find_new_index(cp_index);
1549 if (new_index != 0) {
1550 // the original index is mapped so update w/ new value
1551 RC_TRACE_WITH_THREAD(0x00080000, THREAD,
1552 ("%s@" INTPTR_FORMAT " old=%d, new=%d", Bytecodes::name(c),
1553 bcp, cp_index, new_index));
1554 // Rewriter::rewrite_method() uses put_native_u2() in this
1555 // situation because it is reusing the constant pool index
1556 // location for a native index into the constantPoolCache.
1557 // Since we are updating the constant pool index prior to
1558 // verification and constantPoolCache initialization, we
1559 // need to keep the new index in Java byte order.
1560 Bytes::put_Java_u2(p, new_index);
1561 }
1562 } break;
1563 }
1564 } // end for each bytecode
1565 } // end rewrite_cp_refs_in_method()
1566
1567
1568 // Rewrite constant pool references in the class_annotations field.
1569 bool VM_RedefineClasses::rewrite_cp_refs_in_class_annotations(
1570 instanceKlassHandle scratch_class, TRAPS) {
1571
1572 typeArrayHandle class_annotations(THREAD,
1573 scratch_class->class_annotations());
1574 if (class_annotations.is_null() || class_annotations->length() == 0) {
1575 // no class_annotations so nothing to do
1576 return true;
1577 }
1578
1579 RC_TRACE_WITH_THREAD(0x02000000, THREAD,
1580 ("class_annotations length=%d", class_annotations->length()));
1581
1582 int byte_i = 0; // byte index into class_annotations
1583 return rewrite_cp_refs_in_annotations_typeArray(class_annotations, byte_i,
1584 THREAD);
1585 }
1586
1587
1588 // Rewrite constant pool references in an annotations typeArray. This
1589 // "structure" is adapted from the RuntimeVisibleAnnotations_attribute
1590 // that is described in section 4.8.15 of the 2nd-edition of the VM spec:
1591 //
1592 // annotations_typeArray {
1593 // u2 num_annotations;
1594 // annotation annotations[num_annotations];
1595 // }
1596 //
1597 bool VM_RedefineClasses::rewrite_cp_refs_in_annotations_typeArray(
1598 typeArrayHandle annotations_typeArray, int &byte_i_ref, TRAPS) {
1599
1600 if ((byte_i_ref + 2) > annotations_typeArray->length()) {
1601 // not enough room for num_annotations field
1602 RC_TRACE_WITH_THREAD(0x02000000, THREAD,
1603 ("length() is too small for num_annotations field"));
1604 return false;
1605 }
1606
1607 u2 num_annotations = Bytes::get_Java_u2((address)
1608 annotations_typeArray->byte_at_addr(byte_i_ref));
1609 byte_i_ref += 2;
1610
1611 RC_TRACE_WITH_THREAD(0x02000000, THREAD,
1612 ("num_annotations=%d", num_annotations));
1613
1614 int calc_num_annotations = 0;
1615 for (; calc_num_annotations < num_annotations; calc_num_annotations++) {
1616 if (!rewrite_cp_refs_in_annotation_struct(annotations_typeArray,
1617 byte_i_ref, THREAD)) {
1618 RC_TRACE_WITH_THREAD(0x02000000, THREAD,
1619 ("bad annotation_struct at %d", calc_num_annotations));
1620 // propagate failure back to caller
1621 return false;
1622 }
1623 }
1624 assert(num_annotations == calc_num_annotations, "sanity check");
1625
1626 return true;
1627 } // end rewrite_cp_refs_in_annotations_typeArray()
1628
1629
1630 // Rewrite constant pool references in the annotation struct portion of
1631 // an annotations_typeArray. This "structure" is from section 4.8.15 of
1632 // the 2nd-edition of the VM spec:
1633 //
1634 // struct annotation {
1635 // u2 type_index;
1636 // u2 num_element_value_pairs;
1637 // {
1638 // u2 element_name_index;
1639 // element_value value;
1640 // } element_value_pairs[num_element_value_pairs];
1641 // }
1642 //
1643 bool VM_RedefineClasses::rewrite_cp_refs_in_annotation_struct(
1644 typeArrayHandle annotations_typeArray, int &byte_i_ref, TRAPS) {
1645 if ((byte_i_ref + 2 + 2) > annotations_typeArray->length()) {
1646 // not enough room for smallest annotation_struct
1647 RC_TRACE_WITH_THREAD(0x02000000, THREAD,
1648 ("length() is too small for annotation_struct"));
1649 return false;
1650 }
1651
1652 u2 type_index = rewrite_cp_ref_in_annotation_data(annotations_typeArray,
1653 byte_i_ref, "mapped old type_index=%d", THREAD);
1654
1655 u2 num_element_value_pairs = Bytes::get_Java_u2((address)
1656 annotations_typeArray->byte_at_addr(
1657 byte_i_ref));
1658 byte_i_ref += 2;
1659
1660 RC_TRACE_WITH_THREAD(0x02000000, THREAD,
1661 ("type_index=%d num_element_value_pairs=%d", type_index,
1662 num_element_value_pairs));
1663
1664 int calc_num_element_value_pairs = 0;
1665 for (; calc_num_element_value_pairs < num_element_value_pairs;
1666 calc_num_element_value_pairs++) {
1667 if ((byte_i_ref + 2) > annotations_typeArray->length()) {
1668 // not enough room for another element_name_index, let alone
1669 // the rest of another component
1670 RC_TRACE_WITH_THREAD(0x02000000, THREAD,
1671 ("length() is too small for element_name_index"));
1672 return false;
1673 }
1674
1675 u2 element_name_index = rewrite_cp_ref_in_annotation_data(
1676 annotations_typeArray, byte_i_ref,
1677 "mapped old element_name_index=%d", THREAD);
1678
1679 RC_TRACE_WITH_THREAD(0x02000000, THREAD,
1680 ("element_name_index=%d", element_name_index));
1681
1682 if (!rewrite_cp_refs_in_element_value(annotations_typeArray,
1683 byte_i_ref, THREAD)) {
1684 RC_TRACE_WITH_THREAD(0x02000000, THREAD,
1685 ("bad element_value at %d", calc_num_element_value_pairs));
1686 // propagate failure back to caller
1687 return false;
1688 }
1689 } // end for each component
1690 assert(num_element_value_pairs == calc_num_element_value_pairs,
1691 "sanity check");
1692
1693 return true;
1694 } // end rewrite_cp_refs_in_annotation_struct()
1695
1696
1697 // Rewrite a constant pool reference at the current position in
1698 // annotations_typeArray if needed. Returns the original constant
1699 // pool reference if a rewrite was not needed or the new constant
1700 // pool reference if a rewrite was needed.
1701 u2 VM_RedefineClasses::rewrite_cp_ref_in_annotation_data(
1702 typeArrayHandle annotations_typeArray, int &byte_i_ref,
1703 const char * trace_mesg, TRAPS) {
1704
1705 address cp_index_addr = (address)
1706 annotations_typeArray->byte_at_addr(byte_i_ref);
1707 u2 old_cp_index = Bytes::get_Java_u2(cp_index_addr);
1708 u2 new_cp_index = find_new_index(old_cp_index);
1709 if (new_cp_index != 0) {
1710 RC_TRACE_WITH_THREAD(0x02000000, THREAD, (trace_mesg, old_cp_index));
1711 Bytes::put_Java_u2(cp_index_addr, new_cp_index);
1712 old_cp_index = new_cp_index;
1713 }
1714 byte_i_ref += 2;
1715 return old_cp_index;
1716 }
1717
1718
1719 // Rewrite constant pool references in the element_value portion of an
1720 // annotations_typeArray. This "structure" is from section 4.8.15.1 of
1721 // the 2nd-edition of the VM spec:
1722 //
1723 // struct element_value {
1724 // u1 tag;
1725 // union {
1726 // u2 const_value_index;
1727 // {
1728 // u2 type_name_index;
1729 // u2 const_name_index;
1730 // } enum_const_value;
1731 // u2 class_info_index;
1732 // annotation annotation_value;
1733 // struct {
1734 // u2 num_values;
1735 // element_value values[num_values];
1736 // } array_value;
1737 // } value;
1738 // }
1739 //
1740 bool VM_RedefineClasses::rewrite_cp_refs_in_element_value(
1741 typeArrayHandle annotations_typeArray, int &byte_i_ref, TRAPS) {
1742
1743 if ((byte_i_ref + 1) > annotations_typeArray->length()) {
1744 // not enough room for a tag let alone the rest of an element_value
1745 RC_TRACE_WITH_THREAD(0x02000000, THREAD,
1746 ("length() is too small for a tag"));
1747 return false;
1748 }
1749
1750 u1 tag = annotations_typeArray->byte_at(byte_i_ref);
1751 byte_i_ref++;
1752 RC_TRACE_WITH_THREAD(0x02000000, THREAD, ("tag='%c'", tag));
1753
1754 switch (tag) {
1755 // These BaseType tag values are from Table 4.2 in VM spec:
1756 case 'B': // byte
1757 case 'C': // char
1758 case 'D': // double
1759 case 'F': // float
1760 case 'I': // int
1761 case 'J': // long
1762 case 'S': // short
1763 case 'Z': // boolean
1764
1765 // The remaining tag values are from Table 4.8 in the 2nd-edition of
1766 // the VM spec:
1767 case 's':
1768 {
1769 // For the above tag values (including the BaseType values),
1770 // value.const_value_index is right union field.
1771
1772 if ((byte_i_ref + 2) > annotations_typeArray->length()) {
1773 // not enough room for a const_value_index
1774 RC_TRACE_WITH_THREAD(0x02000000, THREAD,
1775 ("length() is too small for a const_value_index"));
1776 return false;
1777 }
1778
1779 u2 const_value_index = rewrite_cp_ref_in_annotation_data(
1780 annotations_typeArray, byte_i_ref,
1781 "mapped old const_value_index=%d", THREAD);
1782
1783 RC_TRACE_WITH_THREAD(0x02000000, THREAD,
1784 ("const_value_index=%d", const_value_index));
1785 } break;
1786
1787 case 'e':
1788 {
1789 // for the above tag value, value.enum_const_value is right union field
1790
1791 if ((byte_i_ref + 4) > annotations_typeArray->length()) {
1792 // not enough room for a enum_const_value
1793 RC_TRACE_WITH_THREAD(0x02000000, THREAD,
1794 ("length() is too small for a enum_const_value"));
1795 return false;
1796 }
1797
1798 u2 type_name_index = rewrite_cp_ref_in_annotation_data(
1799 annotations_typeArray, byte_i_ref,
1800 "mapped old type_name_index=%d", THREAD);
1801
1802 u2 const_name_index = rewrite_cp_ref_in_annotation_data(
1803 annotations_typeArray, byte_i_ref,
1804 "mapped old const_name_index=%d", THREAD);
1805
1806 RC_TRACE_WITH_THREAD(0x02000000, THREAD,
1807 ("type_name_index=%d const_name_index=%d", type_name_index,
1808 const_name_index));
1809 } break;
1810
1811 case 'c':
1812 {
1813 // for the above tag value, value.class_info_index is right union field
1814
1815 if ((byte_i_ref + 2) > annotations_typeArray->length()) {
1816 // not enough room for a class_info_index
1817 RC_TRACE_WITH_THREAD(0x02000000, THREAD,
1818 ("length() is too small for a class_info_index"));
1819 return false;
1820 }
1821
1822 u2 class_info_index = rewrite_cp_ref_in_annotation_data(
1823 annotations_typeArray, byte_i_ref,
1824 "mapped old class_info_index=%d", THREAD);
1825
1826 RC_TRACE_WITH_THREAD(0x02000000, THREAD,
1827 ("class_info_index=%d", class_info_index));
1828 } break;
1829
1830 case '@':
1831 // For the above tag value, value.attr_value is the right union
1832 // field. This is a nested annotation.
1833 if (!rewrite_cp_refs_in_annotation_struct(annotations_typeArray,
1834 byte_i_ref, THREAD)) {
1835 // propagate failure back to caller
1836 return false;
1837 }
1838 break;
1839
1840 case '[':
1841 {
1842 if ((byte_i_ref + 2) > annotations_typeArray->length()) {
1843 // not enough room for a num_values field
1844 RC_TRACE_WITH_THREAD(0x02000000, THREAD,
1845 ("length() is too small for a num_values field"));
1846 return false;
1847 }
1848
1849 // For the above tag value, value.array_value is the right union
1850 // field. This is an array of nested element_value.
1851 u2 num_values = Bytes::get_Java_u2((address)
1852 annotations_typeArray->byte_at_addr(byte_i_ref));
1853 byte_i_ref += 2;
1854 RC_TRACE_WITH_THREAD(0x02000000, THREAD, ("num_values=%d", num_values));
1855
1856 int calc_num_values = 0;
1857 for (; calc_num_values < num_values; calc_num_values++) {
1858 if (!rewrite_cp_refs_in_element_value(
1859 annotations_typeArray, byte_i_ref, THREAD)) {
1860 RC_TRACE_WITH_THREAD(0x02000000, THREAD,
1861 ("bad nested element_value at %d", calc_num_values));
1862 // propagate failure back to caller
1863 return false;
1864 }
1865 }
1866 assert(num_values == calc_num_values, "sanity check");
1867 } break;
1868
1869 default:
1870 RC_TRACE_WITH_THREAD(0x02000000, THREAD, ("bad tag=0x%x", tag));
1871 return false;
1872 } // end decode tag field
1873
1874 return true;
1875 } // end rewrite_cp_refs_in_element_value()
1876
1877
1878 // Rewrite constant pool references in a fields_annotations field.
1879 bool VM_RedefineClasses::rewrite_cp_refs_in_fields_annotations(
1880 instanceKlassHandle scratch_class, TRAPS) {
1881
1882 objArrayHandle fields_annotations(THREAD,
1883 scratch_class->fields_annotations());
1884
1885 if (fields_annotations.is_null() || fields_annotations->length() == 0) {
1886 // no fields_annotations so nothing to do
1887 return true;
1888 }
1889
1890 RC_TRACE_WITH_THREAD(0x02000000, THREAD,
1891 ("fields_annotations length=%d", fields_annotations->length()));
1892
1893 for (int i = 0; i < fields_annotations->length(); i++) {
1894 typeArrayHandle field_annotations(THREAD,
1895 (typeArrayOop)fields_annotations->obj_at(i));
1896 if (field_annotations.is_null() || field_annotations->length() == 0) {
1897 // this field does not have any annotations so skip it
1898 continue;
1899 }
1900
1901 int byte_i = 0; // byte index into field_annotations
1902 if (!rewrite_cp_refs_in_annotations_typeArray(field_annotations, byte_i,
1903 THREAD)) {
1904 RC_TRACE_WITH_THREAD(0x02000000, THREAD,
1905 ("bad field_annotations at %d", i));
1906 // propagate failure back to caller
1907 return false;
1908 }
1909 }
1910
1911 return true;
1912 } // end rewrite_cp_refs_in_fields_annotations()
1913
1914
1915 // Rewrite constant pool references in a methods_annotations field.
1916 bool VM_RedefineClasses::rewrite_cp_refs_in_methods_annotations(
1917 instanceKlassHandle scratch_class, TRAPS) {
1918
1919 objArrayHandle methods_annotations(THREAD,
1920 scratch_class->methods_annotations());
1921
1922 if (methods_annotations.is_null() || methods_annotations->length() == 0) {
1923 // no methods_annotations so nothing to do
1924 return true;
1925 }
1926
1927 RC_TRACE_WITH_THREAD(0x02000000, THREAD,
1928 ("methods_annotations length=%d", methods_annotations->length()));
1929
1930 for (int i = 0; i < methods_annotations->length(); i++) {
1931 typeArrayHandle method_annotations(THREAD,
1932 (typeArrayOop)methods_annotations->obj_at(i));
1933 if (method_annotations.is_null() || method_annotations->length() == 0) {
1934 // this method does not have any annotations so skip it
1935 continue;
1936 }
1937
1938 int byte_i = 0; // byte index into method_annotations
1939 if (!rewrite_cp_refs_in_annotations_typeArray(method_annotations, byte_i,
1940 THREAD)) {
1941 RC_TRACE_WITH_THREAD(0x02000000, THREAD,
1942 ("bad method_annotations at %d", i));
1943 // propagate failure back to caller
1944 return false;
1945 }
1946 }
1947
1948 return true;
1949 } // end rewrite_cp_refs_in_methods_annotations()
1950
1951
1952 // Rewrite constant pool references in a methods_parameter_annotations
1953 // field. This "structure" is adapted from the
1954 // RuntimeVisibleParameterAnnotations_attribute described in section
1955 // 4.8.17 of the 2nd-edition of the VM spec:
1956 //
1957 // methods_parameter_annotations_typeArray {
1958 // u1 num_parameters;
1959 // {
1960 // u2 num_annotations;
1961 // annotation annotations[num_annotations];
1962 // } parameter_annotations[num_parameters];
1963 // }
1964 //
1965 bool VM_RedefineClasses::rewrite_cp_refs_in_methods_parameter_annotations(
1966 instanceKlassHandle scratch_class, TRAPS) {
1967
1968 objArrayHandle methods_parameter_annotations(THREAD,
1969 scratch_class->methods_parameter_annotations());
1970
1971 if (methods_parameter_annotations.is_null()
1972 || methods_parameter_annotations->length() == 0) {
1973 // no methods_parameter_annotations so nothing to do
1974 return true;
1975 }
1976
1977 RC_TRACE_WITH_THREAD(0x02000000, THREAD,
1978 ("methods_parameter_annotations length=%d",
1979 methods_parameter_annotations->length()));
1980
1981 for (int i = 0; i < methods_parameter_annotations->length(); i++) {
1982 typeArrayHandle method_parameter_annotations(THREAD,
1983 (typeArrayOop)methods_parameter_annotations->obj_at(i));
1984 if (method_parameter_annotations.is_null()
1985 || method_parameter_annotations->length() == 0) {
1986 // this method does not have any parameter annotations so skip it
1987 continue;
1988 }
1989
1990 if (method_parameter_annotations->length() < 1) {
1991 // not enough room for a num_parameters field
1992 RC_TRACE_WITH_THREAD(0x02000000, THREAD,
1993 ("length() is too small for a num_parameters field at %d", i));
1994 return false;
1995 }
1996
1997 int byte_i = 0; // byte index into method_parameter_annotations
1998
1999 u1 num_parameters = method_parameter_annotations->byte_at(byte_i);
2000 byte_i++;
2001
2002 RC_TRACE_WITH_THREAD(0x02000000, THREAD,
2003 ("num_parameters=%d", num_parameters));
2004
2005 int calc_num_parameters = 0;
2006 for (; calc_num_parameters < num_parameters; calc_num_parameters++) {
2007 if (!rewrite_cp_refs_in_annotations_typeArray(
2008 method_parameter_annotations, byte_i, THREAD)) {
2009 RC_TRACE_WITH_THREAD(0x02000000, THREAD,
2010 ("bad method_parameter_annotations at %d", calc_num_parameters));
2011 // propagate failure back to caller
2012 return false;
2013 }
2014 }
2015 assert(num_parameters == calc_num_parameters, "sanity check");
2016 }
2017
2018 return true;
2019 } // end rewrite_cp_refs_in_methods_parameter_annotations()
2020
2021
2022 // Rewrite constant pool references in a methods_default_annotations
2023 // field. This "structure" is adapted from the AnnotationDefault_attribute
2024 // that is described in section 4.8.19 of the 2nd-edition of the VM spec:
2025 //
2026 // methods_default_annotations_typeArray {
2027 // element_value default_value;
2028 // }
2029 //
2030 bool VM_RedefineClasses::rewrite_cp_refs_in_methods_default_annotations(
2031 instanceKlassHandle scratch_class, TRAPS) {
2032
2033 objArrayHandle methods_default_annotations(THREAD,
2034 scratch_class->methods_default_annotations());
2035
2036 if (methods_default_annotations.is_null()
2037 || methods_default_annotations->length() == 0) {
2038 // no methods_default_annotations so nothing to do
2039 return true;
2040 }
2041
2042 RC_TRACE_WITH_THREAD(0x02000000, THREAD,
2043 ("methods_default_annotations length=%d",
2044 methods_default_annotations->length()));
2045
2046 for (int i = 0; i < methods_default_annotations->length(); i++) {
2047 typeArrayHandle method_default_annotations(THREAD,
2048 (typeArrayOop)methods_default_annotations->obj_at(i));
2049 if (method_default_annotations.is_null()
2050 || method_default_annotations->length() == 0) {
2051 // this method does not have any default annotations so skip it
2052 continue;
2053 }
2054
2055 int byte_i = 0; // byte index into method_default_annotations
2056
2057 if (!rewrite_cp_refs_in_element_value(
2058 method_default_annotations, byte_i, THREAD)) {
2059 RC_TRACE_WITH_THREAD(0x02000000, THREAD,
2060 ("bad default element_value at %d", i));
2061 // propagate failure back to caller
2062 return false;
2063 }
2064 }
2065
2066 return true;
2067 } // end rewrite_cp_refs_in_methods_default_annotations()
2068
2069
2070 // Rewrite constant pool references in the method's stackmap table.
2071 // These "structures" are adapted from the StackMapTable_attribute that
2072 // is described in section 4.8.4 of the 6.0 version of the VM spec
2073 // (dated 2005.10.26):
2074 // file:///net/quincunx.sfbay/export/gbracha/ClassFile-Java6.pdf
2075 //
2076 // stack_map {
2077 // u2 number_of_entries;
2078 // stack_map_frame entries[number_of_entries];
2079 // }
2080 //
2081 void VM_RedefineClasses::rewrite_cp_refs_in_stack_map_table(
2082 methodHandle method, TRAPS) {
2083
2084 if (!method->has_stackmap_table()) {
2085 return;
2086 }
2087
2088 typeArrayOop stackmap_data = method->stackmap_data();
2089 address stackmap_p = (address)stackmap_data->byte_at_addr(0);
2090 address stackmap_end = stackmap_p + stackmap_data->length();
2091
2092 assert(stackmap_p + 2 <= stackmap_end, "no room for number_of_entries");
2093 u2 number_of_entries = Bytes::get_Java_u2(stackmap_p);
2094 stackmap_p += 2;
2095
2096 RC_TRACE_WITH_THREAD(0x04000000, THREAD,
2097 ("number_of_entries=%u", number_of_entries));
2098
2099 // walk through each stack_map_frame
2100 u2 calc_number_of_entries = 0;
2101 for (; calc_number_of_entries < number_of_entries; calc_number_of_entries++) {
2102 // The stack_map_frame structure is a u1 frame_type followed by
2103 // 0 or more bytes of data:
2104 //
2105 // union stack_map_frame {
2106 // same_frame;
2107 // same_locals_1_stack_item_frame;
2108 // same_locals_1_stack_item_frame_extended;
2109 // chop_frame;
2110 // same_frame_extended;
2111 // append_frame;
2112 // full_frame;
2113 // }
2114
2115 assert(stackmap_p + 1 <= stackmap_end, "no room for frame_type");
2116 // The Linux compiler does not like frame_type to be u1 or u2. It
2117 // issues the following warning for the first if-statement below:
2118 //
2119 // "warning: comparison is always true due to limited range of data type"
2120 //
2121 u4 frame_type = *stackmap_p;
2122 stackmap_p++;
2123
2124 // same_frame {
2125 // u1 frame_type = SAME; /* 0-63 */
2126 // }
2127 if (frame_type >= 0 && frame_type <= 63) {
2128 // nothing more to do for same_frame
2129 }
2130
2131 // same_locals_1_stack_item_frame {
2132 // u1 frame_type = SAME_LOCALS_1_STACK_ITEM; /* 64-127 */
2133 // verification_type_info stack[1];
2134 // }
2135 else if (frame_type >= 64 && frame_type <= 127) {
2136 rewrite_cp_refs_in_verification_type_info(stackmap_p, stackmap_end,
2137 calc_number_of_entries, frame_type, THREAD);
2138 }
2139
2140 // reserved for future use
2141 else if (frame_type >= 128 && frame_type <= 246) {
2142 // nothing more to do for reserved frame_types
2143 }
2144
2145 // same_locals_1_stack_item_frame_extended {
2146 // u1 frame_type = SAME_LOCALS_1_STACK_ITEM_EXTENDED; /* 247 */
2147 // u2 offset_delta;
2148 // verification_type_info stack[1];
2149 // }
2150 else if (frame_type == 247) {
2151 stackmap_p += 2;
2152 rewrite_cp_refs_in_verification_type_info(stackmap_p, stackmap_end,
2153 calc_number_of_entries, frame_type, THREAD);
2154 }
2155
2156 // chop_frame {
2157 // u1 frame_type = CHOP; /* 248-250 */
2158 // u2 offset_delta;
2159 // }
2160 else if (frame_type >= 248 && frame_type <= 250) {
2161 stackmap_p += 2;
2162 }
2163
2164 // same_frame_extended {
2165 // u1 frame_type = SAME_FRAME_EXTENDED; /* 251*/
2166 // u2 offset_delta;
2167 // }
2168 else if (frame_type == 251) {
2169 stackmap_p += 2;
2170 }
2171
2172 // append_frame {
2173 // u1 frame_type = APPEND; /* 252-254 */
2174 // u2 offset_delta;
2175 // verification_type_info locals[frame_type - 251];
2176 // }
2177 else if (frame_type >= 252 && frame_type <= 254) {
2178 assert(stackmap_p + 2 <= stackmap_end,
2179 "no room for offset_delta");
2180 stackmap_p += 2;
2181 u1 len = frame_type - 251;
2182 for (u1 i = 0; i < len; i++) {
2183 rewrite_cp_refs_in_verification_type_info(stackmap_p, stackmap_end,
2184 calc_number_of_entries, frame_type, THREAD);
2185 }
2186 }
2187
2188 // full_frame {
2189 // u1 frame_type = FULL_FRAME; /* 255 */
2190 // u2 offset_delta;
2191 // u2 number_of_locals;
2192 // verification_type_info locals[number_of_locals];
2193 // u2 number_of_stack_items;
2194 // verification_type_info stack[number_of_stack_items];
2195 // }
2196 else if (frame_type == 255) {
2197 assert(stackmap_p + 2 + 2 <= stackmap_end,
2198 "no room for smallest full_frame");
2199 stackmap_p += 2;
2200
2201 u2 number_of_locals = Bytes::get_Java_u2(stackmap_p);
2202 stackmap_p += 2;
2203
2204 for (u2 locals_i = 0; locals_i < number_of_locals; locals_i++) {
2205 rewrite_cp_refs_in_verification_type_info(stackmap_p, stackmap_end,
2206 calc_number_of_entries, frame_type, THREAD);
2207 }
2208
2209 // Use the largest size for the number_of_stack_items, but only get
2210 // the right number of bytes.
2211 u2 number_of_stack_items = Bytes::get_Java_u2(stackmap_p);
2212 stackmap_p += 2;
2213
2214 for (u2 stack_i = 0; stack_i < number_of_stack_items; stack_i++) {
2215 rewrite_cp_refs_in_verification_type_info(stackmap_p, stackmap_end,
2216 calc_number_of_entries, frame_type, THREAD);
2217 }
2218 }
2219 } // end while there is a stack_map_frame
2220 assert(number_of_entries == calc_number_of_entries, "sanity check");
2221 } // end rewrite_cp_refs_in_stack_map_table()
2222
2223
2224 // Rewrite constant pool references in the verification type info
2225 // portion of the method's stackmap table. These "structures" are
2226 // adapted from the StackMapTable_attribute that is described in
2227 // section 4.8.4 of the 6.0 version of the VM spec (dated 2005.10.26):
2228 // file:///net/quincunx.sfbay/export/gbracha/ClassFile-Java6.pdf
2229 //
2230 // The verification_type_info structure is a u1 tag followed by 0 or
2231 // more bytes of data:
2232 //
2233 // union verification_type_info {
2234 // Top_variable_info;
2235 // Integer_variable_info;
2236 // Float_variable_info;
2237 // Long_variable_info;
2238 // Double_variable_info;
2239 // Null_variable_info;
2240 // UninitializedThis_variable_info;
2241 // Object_variable_info;
2242 // Uninitialized_variable_info;
2243 // }
2244 //
2245 void VM_RedefineClasses::rewrite_cp_refs_in_verification_type_info(
2246 address& stackmap_p_ref, address stackmap_end, u2 frame_i,
2247 u1 frame_type, TRAPS) {
2248
2249 assert(stackmap_p_ref + 1 <= stackmap_end, "no room for tag");
2250 u1 tag = *stackmap_p_ref;
2251 stackmap_p_ref++;
2252
2253 switch (tag) {
2254 // Top_variable_info {
2255 // u1 tag = ITEM_Top; /* 0 */
2256 // }
2257 // verificationType.hpp has zero as ITEM_Bogus instead of ITEM_Top
2258 case 0: // fall through
2259
2260 // Integer_variable_info {
2261 // u1 tag = ITEM_Integer; /* 1 */
2262 // }
2263 case ITEM_Integer: // fall through
2264
2265 // Float_variable_info {
2266 // u1 tag = ITEM_Float; /* 2 */
2267 // }
2268 case ITEM_Float: // fall through
2269
2270 // Double_variable_info {
2271 // u1 tag = ITEM_Double; /* 3 */
2272 // }
2273 case ITEM_Double: // fall through
2274
2275 // Long_variable_info {
2276 // u1 tag = ITEM_Long; /* 4 */
2277 // }
2278 case ITEM_Long: // fall through
2279
2280 // Null_variable_info {
2281 // u1 tag = ITEM_Null; /* 5 */
2282 // }
2283 case ITEM_Null: // fall through
2284
2285 // UninitializedThis_variable_info {
2286 // u1 tag = ITEM_UninitializedThis; /* 6 */
2287 // }
2288 case ITEM_UninitializedThis:
2289 // nothing more to do for the above tag types
2290 break;
2291
2292 // Object_variable_info {
2293 // u1 tag = ITEM_Object; /* 7 */
2294 // u2 cpool_index;
2295 // }
2296 case ITEM_Object:
2297 {
2298 assert(stackmap_p_ref + 2 <= stackmap_end, "no room for cpool_index");
2299 u2 cpool_index = Bytes::get_Java_u2(stackmap_p_ref);
2300 u2 new_cp_index = find_new_index(cpool_index);
2301 if (new_cp_index != 0) {
2302 RC_TRACE_WITH_THREAD(0x04000000, THREAD,
2303 ("mapped old cpool_index=%d", cpool_index));
2304 Bytes::put_Java_u2(stackmap_p_ref, new_cp_index);
2305 cpool_index = new_cp_index;
2306 }
2307 stackmap_p_ref += 2;
2308
2309 RC_TRACE_WITH_THREAD(0x04000000, THREAD,
2310 ("frame_i=%u, frame_type=%u, cpool_index=%d", frame_i,
2311 frame_type, cpool_index));
2312 } break;
2313
2314 // Uninitialized_variable_info {
2315 // u1 tag = ITEM_Uninitialized; /* 8 */
2316 // u2 offset;
2317 // }
2318 case ITEM_Uninitialized:
2319 assert(stackmap_p_ref + 2 <= stackmap_end, "no room for offset");
2320 stackmap_p_ref += 2;
2321 break;
2322
2323 default:
2324 RC_TRACE_WITH_THREAD(0x04000000, THREAD,
2325 ("frame_i=%u, frame_type=%u, bad tag=0x%x", frame_i, frame_type, tag));
2326 ShouldNotReachHere();
2327 break;
2328 } // end switch (tag)
2329 } // end rewrite_cp_refs_in_verification_type_info()
2330
2331
2332 // Change the constant pool associated with klass scratch_class to
2333 // scratch_cp. If shrink is true, then scratch_cp_length elements
2334 // are copied from scratch_cp to a smaller constant pool and the
2335 // smaller constant pool is associated with scratch_class.
2336 void VM_RedefineClasses::set_new_constant_pool(
2337 instanceKlassHandle scratch_class, constantPoolHandle scratch_cp,
2338 int scratch_cp_length, bool shrink, TRAPS) {
2339 assert(!shrink || scratch_cp->length() >= scratch_cp_length, "sanity check");
2340
2341 if (shrink) {
2342 // scratch_cp is a merged constant pool and has enough space for a
2343 // worst case merge situation. We want to associate the minimum
2344 // sized constant pool with the klass to save space.
2345 constantPoolHandle smaller_cp(THREAD,
2346 oopFactory::new_constantPool(scratch_cp_length,
2347 oopDesc::IsUnsafeConc,
2348 THREAD));
2349 // preserve orig_length() value in the smaller copy
2350 int orig_length = scratch_cp->orig_length();
2351 assert(orig_length != 0, "sanity check");
2352 smaller_cp->set_orig_length(orig_length);
2353 scratch_cp->copy_cp_to(1, scratch_cp_length - 1, smaller_cp, 1, THREAD);
2354 scratch_cp = smaller_cp;
2355 smaller_cp()->set_is_conc_safe(true);
2356 }
2357
2358 // attach new constant pool to klass
2359 scratch_cp->set_pool_holder(scratch_class());
2360
2361 // attach klass to new constant pool
2362 scratch_class->set_constants(scratch_cp());
2363
2364 int i; // for portability
2365
2366 // update each field in klass to use new constant pool indices as needed
2367 for (JavaFieldStream fs(scratch_class); !fs.done(); fs.next()) {
2368 jshort cur_index = fs.name_index();
2369 jshort new_index = find_new_index(cur_index);
2370 if (new_index != 0) {
2371 RC_TRACE_WITH_THREAD(0x00080000, THREAD,
2372 ("field-name_index change: %d to %d", cur_index, new_index));
2373 fs.set_name_index(new_index);
2374 }
2375 cur_index = fs.signature_index();
2376 new_index = find_new_index(cur_index);
2377 if (new_index != 0) {
2378 RC_TRACE_WITH_THREAD(0x00080000, THREAD,
2379 ("field-signature_index change: %d to %d", cur_index, new_index));
2380 fs.set_signature_index(new_index);
2381 }
2382 cur_index = fs.initval_index();
2383 new_index = find_new_index(cur_index);
2384 if (new_index != 0) {
2385 RC_TRACE_WITH_THREAD(0x00080000, THREAD,
2386 ("field-initval_index change: %d to %d", cur_index, new_index));
2387 fs.set_initval_index(new_index);
2388 }
2389 cur_index = fs.generic_signature_index();
2390 new_index = find_new_index(cur_index);
2391 if (new_index != 0) {
2392 RC_TRACE_WITH_THREAD(0x00080000, THREAD,
2393 ("field-generic_signature change: %d to %d", cur_index, new_index));
2394 fs.set_generic_signature_index(new_index);
2395 }
2396 } // end for each field
2397
2398 // Update constant pool indices in the inner classes info to use
2399 // new constant indices as needed. The inner classes info is a
2400 // quadruple:
2401 // (inner_class_info, outer_class_info, inner_name, inner_access_flags)
2402 typeArrayOop inner_class_list = scratch_class->inner_classes();
2403 int icl_length = (inner_class_list == NULL) ? 0 : inner_class_list->length();
2404 if (icl_length > 0) {
2405 typeArrayHandle inner_class_list_h(THREAD, inner_class_list);
2406 for (int i = 0; i < icl_length;
2407 i += instanceKlass::inner_class_next_offset) {
2408 int cur_index = inner_class_list_h->ushort_at(i
2409 + instanceKlass::inner_class_inner_class_info_offset);
2410 if (cur_index == 0) {
2411 continue; // JVM spec. allows null inner class refs so skip it
2412 }
2413 int new_index = find_new_index(cur_index);
2414 if (new_index != 0) {
2415 RC_TRACE_WITH_THREAD(0x00080000, THREAD,
2416 ("inner_class_info change: %d to %d", cur_index, new_index));
2417 inner_class_list_h->ushort_at_put(i
2418 + instanceKlass::inner_class_inner_class_info_offset, new_index);
2419 }
2420 cur_index = inner_class_list_h->ushort_at(i
2421 + instanceKlass::inner_class_outer_class_info_offset);
2422 new_index = find_new_index(cur_index);
2423 if (new_index != 0) {
2424 RC_TRACE_WITH_THREAD(0x00080000, THREAD,
2425 ("outer_class_info change: %d to %d", cur_index, new_index));
2426 inner_class_list_h->ushort_at_put(i
2427 + instanceKlass::inner_class_outer_class_info_offset, new_index);
2428 }
2429 cur_index = inner_class_list_h->ushort_at(i
2430 + instanceKlass::inner_class_inner_name_offset);
2431 new_index = find_new_index(cur_index);
2432 if (new_index != 0) {
2433 RC_TRACE_WITH_THREAD(0x00080000, THREAD,
2434 ("inner_name change: %d to %d", cur_index, new_index));
2435 inner_class_list_h->ushort_at_put(i
2436 + instanceKlass::inner_class_inner_name_offset, new_index);
2437 }
2438 } // end for each inner class
2439 } // end if we have inner classes
2440
2441 // Attach each method in klass to the new constant pool and update
2442 // to use new constant pool indices as needed:
2443 objArrayHandle methods(THREAD, scratch_class->methods());
2444 for (i = methods->length() - 1; i >= 0; i--) {
2445 methodHandle method(THREAD, (methodOop)methods->obj_at(i));
2446 method->set_constants(scratch_cp());
2447
2448 int new_index = find_new_index(method->name_index());
2449 if (new_index != 0) {
2450 RC_TRACE_WITH_THREAD(0x00080000, THREAD,
2451 ("method-name_index change: %d to %d", method->name_index(),
2452 new_index));
2453 method->set_name_index(new_index);
2454 }
2455 new_index = find_new_index(method->signature_index());
2456 if (new_index != 0) {
2457 RC_TRACE_WITH_THREAD(0x00080000, THREAD,
2458 ("method-signature_index change: %d to %d",
2459 method->signature_index(), new_index));
2460 method->set_signature_index(new_index);
2461 }
2462 new_index = find_new_index(method->generic_signature_index());
2463 if (new_index != 0) {
2464 RC_TRACE_WITH_THREAD(0x00080000, THREAD,
2465 ("method-generic_signature_index change: %d to %d",
2466 method->generic_signature_index(), new_index));
2467 method->set_generic_signature_index(new_index);
2468 }
2469
2470 // Update constant pool indices in the method's checked exception
2471 // table to use new constant indices as needed.
2472 int cext_length = method->checked_exceptions_length();
2473 if (cext_length > 0) {
2474 CheckedExceptionElement * cext_table =
2475 method->checked_exceptions_start();
2476 for (int j = 0; j < cext_length; j++) {
2477 int cur_index = cext_table[j].class_cp_index;
2478 int new_index = find_new_index(cur_index);
2479 if (new_index != 0) {
2480 RC_TRACE_WITH_THREAD(0x00080000, THREAD,
2481 ("cext-class_cp_index change: %d to %d", cur_index, new_index));
2482 cext_table[j].class_cp_index = (u2)new_index;
2483 }
2484 } // end for each checked exception table entry
2485 } // end if there are checked exception table entries
2486
2487 // Update each catch type index in the method's exception table
2488 // to use new constant pool indices as needed. The exception table
2489 // holds quadruple entries of the form:
2490 // (beg_bci, end_bci, handler_bci, klass_index)
2491 const int beg_bci_offset = 0;
2492 const int end_bci_offset = 1;
2493 const int handler_bci_offset = 2;
2494 const int klass_index_offset = 3;
2495 const int entry_size = 4;
2496
2497 typeArrayHandle ex_table (THREAD, method->exception_table());
2498 int ext_length = ex_table->length();
2499 assert(ext_length % entry_size == 0, "exception table format has changed");
2500
2501 for (int j = 0; j < ext_length; j += entry_size) {
2502 int cur_index = ex_table->int_at(j + klass_index_offset);
2503 int new_index = find_new_index(cur_index);
2504 if (new_index != 0) {
2505 RC_TRACE_WITH_THREAD(0x00080000, THREAD,
2506 ("ext-klass_index change: %d to %d", cur_index, new_index));
2507 ex_table->int_at_put(j + klass_index_offset, new_index);
2508 }
2509 } // end for each exception table entry
2510
2511 // Update constant pool indices in the method's local variable
2512 // table to use new constant indices as needed. The local variable
2513 // table hold sextuple entries of the form:
2514 // (start_pc, length, name_index, descriptor_index, signature_index, slot)
2515 int lvt_length = method->localvariable_table_length();
2516 if (lvt_length > 0) {
2517 LocalVariableTableElement * lv_table =
2518 method->localvariable_table_start();
2519 for (int j = 0; j < lvt_length; j++) {
2520 int cur_index = lv_table[j].name_cp_index;
2521 int new_index = find_new_index(cur_index);
2522 if (new_index != 0) {
2523 RC_TRACE_WITH_THREAD(0x00080000, THREAD,
2524 ("lvt-name_cp_index change: %d to %d", cur_index, new_index));
2525 lv_table[j].name_cp_index = (u2)new_index;
2526 }
2527 cur_index = lv_table[j].descriptor_cp_index;
2528 new_index = find_new_index(cur_index);
2529 if (new_index != 0) {
2530 RC_TRACE_WITH_THREAD(0x00080000, THREAD,
2531 ("lvt-descriptor_cp_index change: %d to %d", cur_index,
2532 new_index));
2533 lv_table[j].descriptor_cp_index = (u2)new_index;
2534 }
2535 cur_index = lv_table[j].signature_cp_index;
2536 new_index = find_new_index(cur_index);
2537 if (new_index != 0) {
2538 RC_TRACE_WITH_THREAD(0x00080000, THREAD,
2539 ("lvt-signature_cp_index change: %d to %d", cur_index, new_index));
2540 lv_table[j].signature_cp_index = (u2)new_index;
2541 }
2542 } // end for each local variable table entry
2543 } // end if there are local variable table entries
2544
2545 rewrite_cp_refs_in_stack_map_table(method, THREAD);
2546 } // end for each method
2547 assert(scratch_cp()->is_conc_safe(), "Just checking");
2548 } // end set_new_constant_pool()
2549
2550
2551 // Unevolving classes may point to methods of the_class directly
2552 // from their constant pool caches, itables, and/or vtables. We
2553 // use the SystemDictionary::classes_do() facility and this helper
2554 // to fix up these pointers.
2555 //
2556 // Note: We currently don't support updating the vtable in
2557 // arrayKlassOops. See Open Issues in jvmtiRedefineClasses.hpp.
2558 void VM_RedefineClasses::adjust_cpool_cache_and_vtable(klassOop k_oop,
2559 oop initiating_loader, TRAPS) {
2560 Klass *k = k_oop->klass_part();
2561 if (k->oop_is_instance()) {
2562 HandleMark hm(THREAD);
2563 instanceKlass *ik = (instanceKlass *) k;
2564
2565 // HotSpot specific optimization! HotSpot does not currently
2566 // support delegation from the bootstrap class loader to a
2567 // user-defined class loader. This means that if the bootstrap
2568 // class loader is the initiating class loader, then it will also
2569 // be the defining class loader. This also means that classes
2570 // loaded by the bootstrap class loader cannot refer to classes
2571 // loaded by a user-defined class loader. Note: a user-defined
2572 // class loader can delegate to the bootstrap class loader.
2573 //
2574 // If the current class being redefined has a user-defined class
2575 // loader as its defining class loader, then we can skip all
2576 // classes loaded by the bootstrap class loader.
2577 bool is_user_defined =
2578 instanceKlass::cast(_the_class_oop)->class_loader() != NULL;
2579 if (is_user_defined && ik->class_loader() == NULL) {
2580 return;
2581 }
2582
2583 // This is a very busy routine. We don't want too much tracing
2584 // printed out.
2585 bool trace_name_printed = false;
2586
2587 // Very noisy: only enable this call if you are trying to determine
2588 // that a specific class gets found by this routine.
2589 // RC_TRACE macro has an embedded ResourceMark
2590 // RC_TRACE_WITH_THREAD(0x00100000, THREAD,
2591 // ("adjust check: name=%s", ik->external_name()));
2592 // trace_name_printed = true;
2593
2594 // Fix the vtable embedded in the_class and subclasses of the_class,
2595 // if one exists. We discard scratch_class and we don't keep an
2596 // instanceKlass around to hold obsolete methods so we don't have
2597 // any other instanceKlass embedded vtables to update. The vtable
2598 // holds the methodOops for virtual (but not final) methods.
2599 if (ik->vtable_length() > 0 && ik->is_subtype_of(_the_class_oop)) {
2600 // ik->vtable() creates a wrapper object; rm cleans it up
2601 ResourceMark rm(THREAD);
2602 ik->vtable()->adjust_method_entries(_matching_old_methods,
2603 _matching_new_methods,
2604 _matching_methods_length,
2605 &trace_name_printed);
2606 }
2607
2608 // If the current class has an itable and we are either redefining an
2609 // interface or if the current class is a subclass of the_class, then
2610 // we potentially have to fix the itable. If we are redefining an
2611 // interface, then we have to call adjust_method_entries() for
2612 // every instanceKlass that has an itable since there isn't a
2613 // subclass relationship between an interface and an instanceKlass.
2614 if (ik->itable_length() > 0 && (Klass::cast(_the_class_oop)->is_interface()
2615 || ik->is_subclass_of(_the_class_oop))) {
2616 // ik->itable() creates a wrapper object; rm cleans it up
2617 ResourceMark rm(THREAD);
2618 ik->itable()->adjust_method_entries(_matching_old_methods,
2619 _matching_new_methods,
2620 _matching_methods_length,
2621 &trace_name_printed);
2622 }
2623
2624 // The constant pools in other classes (other_cp) can refer to
2625 // methods in the_class. We have to update method information in
2626 // other_cp's cache. If other_cp has a previous version, then we
2627 // have to repeat the process for each previous version. The
2628 // constant pool cache holds the methodOops for non-virtual
2629 // methods and for virtual, final methods.
2630 //
2631 // Special case: if the current class is the_class, then new_cp
2632 // has already been attached to the_class and old_cp has already
2633 // been added as a previous version. The new_cp doesn't have any
2634 // cached references to old methods so it doesn't need to be
2635 // updated. We can simply start with the previous version(s) in
2636 // that case.
2637 constantPoolHandle other_cp;
2638 constantPoolCacheOop cp_cache;
2639
2640 if (k_oop != _the_class_oop) {
2641 // this klass' constant pool cache may need adjustment
2642 other_cp = constantPoolHandle(ik->constants());
2643 cp_cache = other_cp->cache();
2644 if (cp_cache != NULL) {
2645 cp_cache->adjust_method_entries(_matching_old_methods,
2646 _matching_new_methods,
2647 _matching_methods_length,
2648 &trace_name_printed);
2649 }
2650 }
2651 {
2652 ResourceMark rm(THREAD);
2653 // PreviousVersionInfo objects returned via PreviousVersionWalker
2654 // contain a GrowableArray of handles. We have to clean up the
2655 // GrowableArray _after_ the PreviousVersionWalker destructor
2656 // has destroyed the handles.
2657 {
2658 // the previous versions' constant pool caches may need adjustment
2659 PreviousVersionWalker pvw(ik);
2660 for (PreviousVersionInfo * pv_info = pvw.next_previous_version();
2661 pv_info != NULL; pv_info = pvw.next_previous_version()) {
2662 other_cp = pv_info->prev_constant_pool_handle();
2663 cp_cache = other_cp->cache();
2664 if (cp_cache != NULL) {
2665 cp_cache->adjust_method_entries(_matching_old_methods,
2666 _matching_new_methods,
2667 _matching_methods_length,
2668 &trace_name_printed);
2669 }
2670 }
2671 } // pvw is cleaned up
2672 } // rm is cleaned up
2673 }
2674 }
2675
2676 void VM_RedefineClasses::update_jmethod_ids() {
2677 for (int j = 0; j < _matching_methods_length; ++j) {
2678 methodOop old_method = _matching_old_methods[j];
2679 jmethodID jmid = old_method->find_jmethod_id_or_null();
2680 if (jmid != NULL) {
2681 // There is a jmethodID, change it to point to the new method
2682 methodHandle new_method_h(_matching_new_methods[j]);
2683 JNIHandles::change_method_associated_with_jmethod_id(jmid, new_method_h);
2684 assert(JNIHandles::resolve_jmethod_id(jmid) == _matching_new_methods[j],
2685 "should be replaced");
2686 }
2687 }
2688 }
2689
2690 void VM_RedefineClasses::check_methods_and_mark_as_obsolete(
2691 BitMap *emcp_methods, int * emcp_method_count_p) {
2692 *emcp_method_count_p = 0;
2693 int obsolete_count = 0;
2694 int old_index = 0;
2695 for (int j = 0; j < _matching_methods_length; ++j, ++old_index) {
2696 methodOop old_method = _matching_old_methods[j];
2697 methodOop new_method = _matching_new_methods[j];
2698 methodOop old_array_method;
2699
2700 // Maintain an old_index into the _old_methods array by skipping
2701 // deleted methods
2702 while ((old_array_method = (methodOop) _old_methods->obj_at(old_index))
2703 != old_method) {
2704 ++old_index;
2705 }
2706
2707 if (MethodComparator::methods_EMCP(old_method, new_method)) {
2708 // The EMCP definition from JSR-163 requires the bytecodes to be
2709 // the same with the exception of constant pool indices which may
2710 // differ. However, the constants referred to by those indices
2711 // must be the same.
2712 //
2713 // We use methods_EMCP() for comparison since constant pool
2714 // merging can remove duplicate constant pool entries that were
2715 // present in the old method and removed from the rewritten new
2716 // method. A faster binary comparison function would consider the
2717 // old and new methods to be different when they are actually
2718 // EMCP.
2719 //
2720 // The old and new methods are EMCP and you would think that we
2721 // could get rid of one of them here and now and save some space.
2722 // However, the concept of EMCP only considers the bytecodes and
2723 // the constant pool entries in the comparison. Other things,
2724 // e.g., the line number table (LNT) or the local variable table
2725 // (LVT) don't count in the comparison. So the new (and EMCP)
2726 // method can have a new LNT that we need so we can't just
2727 // overwrite the new method with the old method.
2728 //
2729 // When this routine is called, we have already attached the new
2730 // methods to the_class so the old methods are effectively
2731 // overwritten. However, if an old method is still executing,
2732 // then the old method cannot be collected until sometime after
2733 // the old method call has returned. So the overwriting of old
2734 // methods by new methods will save us space except for those
2735 // (hopefully few) old methods that are still executing.
2736 //
2737 // A method refers to a constMethodOop and this presents another
2738 // possible avenue to space savings. The constMethodOop in the
2739 // new method contains possibly new attributes (LNT, LVT, etc).
2740 // At first glance, it seems possible to save space by replacing
2741 // the constMethodOop in the old method with the constMethodOop
2742 // from the new method. The old and new methods would share the
2743 // same constMethodOop and we would save the space occupied by
2744 // the old constMethodOop. However, the constMethodOop contains
2745 // a back reference to the containing method. Sharing the
2746 // constMethodOop between two methods could lead to confusion in
2747 // the code that uses the back reference. This would lead to
2748 // brittle code that could be broken in non-obvious ways now or
2749 // in the future.
2750 //
2751 // Another possibility is to copy the constMethodOop from the new
2752 // method to the old method and then overwrite the new method with
2753 // the old method. Since the constMethodOop contains the bytecodes
2754 // for the method embedded in the oop, this option would change
2755 // the bytecodes out from under any threads executing the old
2756 // method and make the thread's bcp invalid. Since EMCP requires
2757 // that the bytecodes be the same modulo constant pool indices, it
2758 // is straight forward to compute the correct new bcp in the new
2759 // constMethodOop from the old bcp in the old constMethodOop. The
2760 // time consuming part would be searching all the frames in all
2761 // of the threads to find all of the calls to the old method.
2762 //
2763 // It looks like we will have to live with the limited savings
2764 // that we get from effectively overwriting the old methods
2765 // when the new methods are attached to the_class.
2766
2767 // track which methods are EMCP for add_previous_version() call
2768 emcp_methods->set_bit(old_index);
2769 (*emcp_method_count_p)++;
2770
2771 // An EMCP method is _not_ obsolete. An obsolete method has a
2772 // different jmethodID than the current method. An EMCP method
2773 // has the same jmethodID as the current method. Having the
2774 // same jmethodID for all EMCP versions of a method allows for
2775 // a consistent view of the EMCP methods regardless of which
2776 // EMCP method you happen to have in hand. For example, a
2777 // breakpoint set in one EMCP method will work for all EMCP
2778 // versions of the method including the current one.
2779 } else {
2780 // mark obsolete methods as such
2781 old_method->set_is_obsolete();
2782 obsolete_count++;
2783
2784 // obsolete methods need a unique idnum
2785 u2 num = instanceKlass::cast(_the_class_oop)->next_method_idnum();
2786 if (num != constMethodOopDesc::UNSET_IDNUM) {
2787 // u2 old_num = old_method->method_idnum();
2788 old_method->set_method_idnum(num);
2789 // TO DO: attach obsolete annotations to obsolete method's new idnum
2790 }
2791 // With tracing we try not to "yack" too much. The position of
2792 // this trace assumes there are fewer obsolete methods than
2793 // EMCP methods.
2794 RC_TRACE(0x00000100, ("mark %s(%s) as obsolete",
2795 old_method->name()->as_C_string(),
2796 old_method->signature()->as_C_string()));
2797 }
2798 old_method->set_is_old();
2799 }
2800 for (int i = 0; i < _deleted_methods_length; ++i) {
2801 methodOop old_method = _deleted_methods[i];
2802
2803 assert(old_method->vtable_index() < 0,
2804 "cannot delete methods with vtable entries");;
2805
2806 // Mark all deleted methods as old and obsolete
2807 old_method->set_is_old();
2808 old_method->set_is_obsolete();
2809 ++obsolete_count;
2810 // With tracing we try not to "yack" too much. The position of
2811 // this trace assumes there are fewer obsolete methods than
2812 // EMCP methods.
2813 RC_TRACE(0x00000100, ("mark deleted %s(%s) as obsolete",
2814 old_method->name()->as_C_string(),
2815 old_method->signature()->as_C_string()));
2816 }
2817 assert((*emcp_method_count_p + obsolete_count) == _old_methods->length(),
2818 "sanity check");
2819 RC_TRACE(0x00000100, ("EMCP_cnt=%d, obsolete_cnt=%d", *emcp_method_count_p,
2820 obsolete_count));
2821 }
2822
2823 // This internal class transfers the native function registration from old methods
2824 // to new methods. It is designed to handle both the simple case of unchanged
2825 // native methods and the complex cases of native method prefixes being added and/or
2826 // removed.
2827 // It expects only to be used during the VM_RedefineClasses op (a safepoint).
2828 //
2829 // This class is used after the new methods have been installed in "the_class".
2830 //
2831 // So, for example, the following must be handled. Where 'm' is a method and
2832 // a number followed by an underscore is a prefix.
2833 //
2834 // Old Name New Name
2835 // Simple transfer to new method m -> m
2836 // Add prefix m -> 1_m
2837 // Remove prefix 1_m -> m
2838 // Simultaneous add of prefixes m -> 3_2_1_m
2839 // Simultaneous removal of prefixes 3_2_1_m -> m
2840 // Simultaneous add and remove 1_m -> 2_m
2841 // Same, caused by prefix removal only 3_2_1_m -> 3_2_m
2842 //
2843 class TransferNativeFunctionRegistration {
2844 private:
2845 instanceKlassHandle the_class;
2846 int prefix_count;
2847 char** prefixes;
2848
2849 // Recursively search the binary tree of possibly prefixed method names.
2850 // Iteration could be used if all agents were well behaved. Full tree walk is
2851 // more resilent to agents not cleaning up intermediate methods.
2852 // Branch at each depth in the binary tree is:
2853 // (1) without the prefix.
2854 // (2) with the prefix.
2855 // where 'prefix' is the prefix at that 'depth' (first prefix, second prefix,...)
2856 methodOop search_prefix_name_space(int depth, char* name_str, size_t name_len,
2857 Symbol* signature) {
2858 TempNewSymbol name_symbol = SymbolTable::probe(name_str, (int)name_len);
2859 if (name_symbol != NULL) {
2860 methodOop method = Klass::cast(the_class())->lookup_method(name_symbol, signature);
2861 if (method != NULL) {
2862 // Even if prefixed, intermediate methods must exist.
2863 if (method->is_native()) {
2864 // Wahoo, we found a (possibly prefixed) version of the method, return it.
2865 return method;
2866 }
2867 if (depth < prefix_count) {
2868 // Try applying further prefixes (other than this one).
2869 method = search_prefix_name_space(depth+1, name_str, name_len, signature);
2870 if (method != NULL) {
2871 return method; // found
2872 }
2873
2874 // Try adding this prefix to the method name and see if it matches
2875 // another method name.
2876 char* prefix = prefixes[depth];
2877 size_t prefix_len = strlen(prefix);
2878 size_t trial_len = name_len + prefix_len;
2879 char* trial_name_str = NEW_RESOURCE_ARRAY(char, trial_len + 1);
2880 strcpy(trial_name_str, prefix);
2881 strcat(trial_name_str, name_str);
2882 method = search_prefix_name_space(depth+1, trial_name_str, trial_len,
2883 signature);
2884 if (method != NULL) {
2885 // If found along this branch, it was prefixed, mark as such
2886 method->set_is_prefixed_native();
2887 return method; // found
2888 }
2889 }
2890 }
2891 }
2892 return NULL; // This whole branch bore nothing
2893 }
2894
2895 // Return the method name with old prefixes stripped away.
2896 char* method_name_without_prefixes(methodOop method) {
2897 Symbol* name = method->name();
2898 char* name_str = name->as_utf8();
2899
2900 // Old prefixing may be defunct, strip prefixes, if any.
2901 for (int i = prefix_count-1; i >= 0; i--) {
2902 char* prefix = prefixes[i];
2903 size_t prefix_len = strlen(prefix);
2904 if (strncmp(prefix, name_str, prefix_len) == 0) {
2905 name_str += prefix_len;
2906 }
2907 }
2908 return name_str;
2909 }
2910
2911 // Strip any prefixes off the old native method, then try to find a
2912 // (possibly prefixed) new native that matches it.
2913 methodOop strip_and_search_for_new_native(methodOop method) {
2914 ResourceMark rm;
2915 char* name_str = method_name_without_prefixes(method);
2916 return search_prefix_name_space(0, name_str, strlen(name_str),
2917 method->signature());
2918 }
2919
2920 public:
2921
2922 // Construct a native method transfer processor for this class.
2923 TransferNativeFunctionRegistration(instanceKlassHandle _the_class) {
2924 assert(SafepointSynchronize::is_at_safepoint(), "sanity check");
2925
2926 the_class = _the_class;
2927 prefixes = JvmtiExport::get_all_native_method_prefixes(&prefix_count);
2928 }
2929
2930 // Attempt to transfer any of the old or deleted methods that are native
2931 void transfer_registrations(methodOop* old_methods, int methods_length) {
2932 for (int j = 0; j < methods_length; j++) {
2933 methodOop old_method = old_methods[j];
2934
2935 if (old_method->is_native() && old_method->has_native_function()) {
2936 methodOop new_method = strip_and_search_for_new_native(old_method);
2937 if (new_method != NULL) {
2938 // Actually set the native function in the new method.
2939 // Redefine does not send events (except CFLH), certainly not this
2940 // behind the scenes re-registration.
2941 new_method->set_native_function(old_method->native_function(),
2942 !methodOopDesc::native_bind_event_is_interesting);
2943 }
2944 }
2945 }
2946 }
2947 };
2948
2949 // Don't lose the association between a native method and its JNI function.
2950 void VM_RedefineClasses::transfer_old_native_function_registrations(instanceKlassHandle the_class) {
2951 TransferNativeFunctionRegistration transfer(the_class);
2952 transfer.transfer_registrations(_deleted_methods, _deleted_methods_length);
2953 transfer.transfer_registrations(_matching_old_methods, _matching_methods_length);
2954 }
2955
2956 // Deoptimize all compiled code that depends on this class.
2957 //
2958 // If the can_redefine_classes capability is obtained in the onload
2959 // phase then the compiler has recorded all dependencies from startup.
2960 // In that case we need only deoptimize and throw away all compiled code
2961 // that depends on the class.
2962 //
2963 // If can_redefine_classes is obtained sometime after the onload
2964 // phase then the dependency information may be incomplete. In that case
2965 // the first call to RedefineClasses causes all compiled code to be
2966 // thrown away. As can_redefine_classes has been obtained then
2967 // all future compilations will record dependencies so second and
2968 // subsequent calls to RedefineClasses need only throw away code
2969 // that depends on the class.
2970 //
2971 void VM_RedefineClasses::flush_dependent_code(instanceKlassHandle k_h, TRAPS) {
2972 assert_locked_or_safepoint(Compile_lock);
2973
2974 // All dependencies have been recorded from startup or this is a second or
2975 // subsequent use of RedefineClasses
2976 if (JvmtiExport::all_dependencies_are_recorded()) {
2977 Universe::flush_evol_dependents_on(k_h);
2978 } else {
2979 CodeCache::mark_all_nmethods_for_deoptimization();
2980
2981 ResourceMark rm(THREAD);
2982 DeoptimizationMarker dm;
2983
2984 // Deoptimize all activations depending on marked nmethods
2985 Deoptimization::deoptimize_dependents();
2986
2987 // Make the dependent methods not entrant (in VM_Deoptimize they are made zombies)
2988 CodeCache::make_marked_nmethods_not_entrant();
2989
2990 // From now on we know that the dependency information is complete
2991 JvmtiExport::set_all_dependencies_are_recorded(true);
2992 }
2993 }
2994
2995 void VM_RedefineClasses::compute_added_deleted_matching_methods() {
2996 methodOop old_method;
2997 methodOop new_method;
2998
2999 _matching_old_methods = NEW_RESOURCE_ARRAY(methodOop, _old_methods->length());
3000 _matching_new_methods = NEW_RESOURCE_ARRAY(methodOop, _old_methods->length());
3001 _added_methods = NEW_RESOURCE_ARRAY(methodOop, _new_methods->length());
3002 _deleted_methods = NEW_RESOURCE_ARRAY(methodOop, _old_methods->length());
3003
3004 _matching_methods_length = 0;
3005 _deleted_methods_length = 0;
3006 _added_methods_length = 0;
3007
3008 int nj = 0;
3009 int oj = 0;
3010 while (true) {
3011 if (oj >= _old_methods->length()) {
3012 if (nj >= _new_methods->length()) {
3013 break; // we've looked at everything, done
3014 }
3015 // New method at the end
3016 new_method = (methodOop) _new_methods->obj_at(nj);
3017 _added_methods[_added_methods_length++] = new_method;
3018 ++nj;
3019 } else if (nj >= _new_methods->length()) {
3020 // Old method, at the end, is deleted
3021 old_method = (methodOop) _old_methods->obj_at(oj);
3022 _deleted_methods[_deleted_methods_length++] = old_method;
3023 ++oj;
3024 } else {
3025 old_method = (methodOop) _old_methods->obj_at(oj);
3026 new_method = (methodOop) _new_methods->obj_at(nj);
3027 if (old_method->name() == new_method->name()) {
3028 if (old_method->signature() == new_method->signature()) {
3029 _matching_old_methods[_matching_methods_length ] = old_method;
3030 _matching_new_methods[_matching_methods_length++] = new_method;
3031 ++nj;
3032 ++oj;
3033 } else {
3034 // added overloaded have already been moved to the end,
3035 // so this is a deleted overloaded method
3036 _deleted_methods[_deleted_methods_length++] = old_method;
3037 ++oj;
3038 }
3039 } else { // names don't match
3040 if (old_method->name()->fast_compare(new_method->name()) > 0) {
3041 // new method
3042 _added_methods[_added_methods_length++] = new_method;
3043 ++nj;
3044 } else {
3045 // deleted method
3046 _deleted_methods[_deleted_methods_length++] = old_method;
3047 ++oj;
3048 }
3049 }
3050 }
3051 }
3052 assert(_matching_methods_length + _deleted_methods_length == _old_methods->length(), "sanity");
3053 assert(_matching_methods_length + _added_methods_length == _new_methods->length(), "sanity");
3054 }
3055
3056
3057
3058 // Install the redefinition of a class:
3059 // - house keeping (flushing breakpoints and caches, deoptimizing
3060 // dependent compiled code)
3061 // - replacing parts in the_class with parts from scratch_class
3062 // - adding a weak reference to track the obsolete but interesting
3063 // parts of the_class
3064 // - adjusting constant pool caches and vtables in other classes
3065 // that refer to methods in the_class. These adjustments use the
3066 // SystemDictionary::classes_do() facility which only allows
3067 // a helper method to be specified. The interesting parameters
3068 // that we would like to pass to the helper method are saved in
3069 // static global fields in the VM operation.
3070 void VM_RedefineClasses::redefine_single_class(jclass the_jclass,
3071 instanceKlassHandle scratch_class, TRAPS) {
3072
3073 RC_TIMER_START(_timer_rsc_phase1);
3074
3075 oop the_class_mirror = JNIHandles::resolve_non_null(the_jclass);
3076 klassOop the_class_oop = java_lang_Class::as_klassOop(the_class_mirror);
3077 instanceKlassHandle the_class = instanceKlassHandle(THREAD, the_class_oop);
3078
3079 #ifndef JVMTI_KERNEL
3080 // Remove all breakpoints in methods of this class
3081 JvmtiBreakpoints& jvmti_breakpoints = JvmtiCurrentBreakpoints::get_jvmti_breakpoints();
3082 jvmti_breakpoints.clearall_in_class_at_safepoint(the_class_oop);
3083 #endif // !JVMTI_KERNEL
3084
3085 if (the_class_oop == Universe::reflect_invoke_cache()->klass()) {
3086 // We are redefining java.lang.reflect.Method. Method.invoke() is
3087 // cached and users of the cache care about each active version of
3088 // the method so we have to track this previous version.
3089 // Do this before methods get switched
3090 Universe::reflect_invoke_cache()->add_previous_version(
3091 the_class->method_with_idnum(Universe::reflect_invoke_cache()->method_idnum()));
3092 }
3093
3094 // Deoptimize all compiled code that depends on this class
3095 flush_dependent_code(the_class, THREAD);
3096
3097 _old_methods = the_class->methods();
3098 _new_methods = scratch_class->methods();
3099 _the_class_oop = the_class_oop;
3100 compute_added_deleted_matching_methods();
3101 update_jmethod_ids();
3102
3103 // Attach new constant pool to the original klass. The original
3104 // klass still refers to the old constant pool (for now).
3105 scratch_class->constants()->set_pool_holder(the_class());
3106
3107 #if 0
3108 // In theory, with constant pool merging in place we should be able
3109 // to save space by using the new, merged constant pool in place of
3110 // the old constant pool(s). By "pool(s)" I mean the constant pool in
3111 // the klass version we are replacing now and any constant pool(s) in
3112 // previous versions of klass. Nice theory, doesn't work in practice.
3113 // When this code is enabled, even simple programs throw NullPointer
3114 // exceptions. I'm guessing that this is caused by some constant pool
3115 // cache difference between the new, merged constant pool and the
3116 // constant pool that was just being used by the klass. I'm keeping
3117 // this code around to archive the idea, but the code has to remain
3118 // disabled for now.
3119
3120 // Attach each old method to the new constant pool. This can be
3121 // done here since we are past the bytecode verification and
3122 // constant pool optimization phases.
3123 for (int i = _old_methods->length() - 1; i >= 0; i--) {
3124 methodOop method = (methodOop)_old_methods->obj_at(i);
3125 method->set_constants(scratch_class->constants());
3126 }
3127
3128 {
3129 // walk all previous versions of the klass
3130 instanceKlass *ik = (instanceKlass *)the_class()->klass_part();
3131 PreviousVersionWalker pvw(ik);
3132 instanceKlassHandle ikh;
3133 do {
3134 ikh = pvw.next_previous_version();
3135 if (!ikh.is_null()) {
3136 ik = ikh();
3137
3138 // attach previous version of klass to the new constant pool
3139 ik->set_constants(scratch_class->constants());
3140
3141 // Attach each method in the previous version of klass to the
3142 // new constant pool
3143 objArrayOop prev_methods = ik->methods();
3144 for (int i = prev_methods->length() - 1; i >= 0; i--) {
3145 methodOop method = (methodOop)prev_methods->obj_at(i);
3146 method->set_constants(scratch_class->constants());
3147 }
3148 }
3149 } while (!ikh.is_null());
3150 }
3151 #endif
3152
3153 // Replace methods and constantpool
3154 the_class->set_methods(_new_methods);
3155 scratch_class->set_methods(_old_methods); // To prevent potential GCing of the old methods,
3156 // and to be able to undo operation easily.
3157
3158 constantPoolOop old_constants = the_class->constants();
3159 the_class->set_constants(scratch_class->constants());
3160 scratch_class->set_constants(old_constants); // See the previous comment.
3161 #if 0
3162 // We are swapping the guts of "the new class" with the guts of "the
3163 // class". Since the old constant pool has just been attached to "the
3164 // new class", it seems logical to set the pool holder in the old
3165 // constant pool also. However, doing this will change the observable
3166 // class hierarchy for any old methods that are still executing. A
3167 // method can query the identity of its "holder" and this query uses
3168 // the method's constant pool link to find the holder. The change in
3169 // holding class from "the class" to "the new class" can confuse
3170 // things.
3171 //
3172 // Setting the old constant pool's holder will also cause
3173 // verification done during vtable initialization below to fail.
3174 // During vtable initialization, the vtable's class is verified to be
3175 // a subtype of the method's holder. The vtable's class is "the
3176 // class" and the method's holder is gotten from the constant pool
3177 // link in the method itself. For "the class"'s directly implemented
3178 // methods, the method holder is "the class" itself (as gotten from
3179 // the new constant pool). The check works fine in this case. The
3180 // check also works fine for methods inherited from super classes.
3181 //
3182 // Miranda methods are a little more complicated. A miranda method is
3183 // provided by an interface when the class implementing the interface
3184 // does not provide its own method. These interfaces are implemented
3185 // internally as an instanceKlass. These special instanceKlasses
3186 // share the constant pool of the class that "implements" the
3187 // interface. By sharing the constant pool, the method holder of a
3188 // miranda method is the class that "implements" the interface. In a
3189 // non-redefine situation, the subtype check works fine. However, if
3190 // the old constant pool's pool holder is modified, then the check
3191 // fails because there is no class hierarchy relationship between the
3192 // vtable's class and "the new class".
3193
3194 old_constants->set_pool_holder(scratch_class());
3195 #endif
3196
3197 // track which methods are EMCP for add_previous_version() call below
3198 BitMap emcp_methods(_old_methods->length());
3199 int emcp_method_count = 0;
3200 emcp_methods.clear(); // clears 0..(length() - 1)
3201 check_methods_and_mark_as_obsolete(&emcp_methods, &emcp_method_count);
3202 transfer_old_native_function_registrations(the_class);
3203
3204 // The class file bytes from before any retransformable agents mucked
3205 // with them was cached on the scratch class, move to the_class.
3206 // Note: we still want to do this if nothing needed caching since it
3207 // should get cleared in the_class too.
3208 the_class->set_cached_class_file(scratch_class->get_cached_class_file_bytes(),
3209 scratch_class->get_cached_class_file_len());
3210
3211 // Replace inner_classes
3212 typeArrayOop old_inner_classes = the_class->inner_classes();
3213 the_class->set_inner_classes(scratch_class->inner_classes());
3214 scratch_class->set_inner_classes(old_inner_classes);
3215
3216 // Initialize the vtable and interface table after
3217 // methods have been rewritten
3218 {
3219 ResourceMark rm(THREAD);
3220 // no exception should happen here since we explicitly
3221 // do not check loader constraints.
3222 // compare_and_normalize_class_versions has already checked:
3223 // - classloaders unchanged, signatures unchanged
3224 // - all instanceKlasses for redefined classes reused & contents updated
3225 the_class->vtable()->initialize_vtable(false, THREAD);
3226 the_class->itable()->initialize_itable(false, THREAD);
3227 assert(!HAS_PENDING_EXCEPTION || (THREAD->pending_exception()->is_a(SystemDictionary::ThreadDeath_klass())), "redefine exception");
3228 }
3229
3230 // Leave arrays of jmethodIDs and itable index cache unchanged
3231
3232 // Copy the "source file name" attribute from new class version
3233 the_class->set_source_file_name(scratch_class->source_file_name());
3234
3235 // Copy the "source debug extension" attribute from new class version
3236 the_class->set_source_debug_extension(
3237 scratch_class->source_debug_extension());
3238
3239 // Use of javac -g could be different in the old and the new
3240 if (scratch_class->access_flags().has_localvariable_table() !=
3241 the_class->access_flags().has_localvariable_table()) {
3242
3243 AccessFlags flags = the_class->access_flags();
3244 if (scratch_class->access_flags().has_localvariable_table()) {
3245 flags.set_has_localvariable_table();
3246 } else {
3247 flags.clear_has_localvariable_table();
3248 }
3249 the_class->set_access_flags(flags);
3250 }
3251
3252 // Replace class annotation fields values
3253 typeArrayOop old_class_annotations = the_class->class_annotations();
3254 the_class->set_class_annotations(scratch_class->class_annotations());
3255 scratch_class->set_class_annotations(old_class_annotations);
3256
3257 // Replace fields annotation fields values
3258 objArrayOop old_fields_annotations = the_class->fields_annotations();
3259 the_class->set_fields_annotations(scratch_class->fields_annotations());
3260 scratch_class->set_fields_annotations(old_fields_annotations);
3261
3262 // Replace methods annotation fields values
3263 objArrayOop old_methods_annotations = the_class->methods_annotations();
3264 the_class->set_methods_annotations(scratch_class->methods_annotations());
3265 scratch_class->set_methods_annotations(old_methods_annotations);
3266
3267 // Replace methods parameter annotation fields values
3268 objArrayOop old_methods_parameter_annotations =
3269 the_class->methods_parameter_annotations();
3270 the_class->set_methods_parameter_annotations(
3271 scratch_class->methods_parameter_annotations());
3272 scratch_class->set_methods_parameter_annotations(old_methods_parameter_annotations);
3273
3274 // Replace methods default annotation fields values
3275 objArrayOop old_methods_default_annotations =
3276 the_class->methods_default_annotations();
3277 the_class->set_methods_default_annotations(
3278 scratch_class->methods_default_annotations());
3279 scratch_class->set_methods_default_annotations(old_methods_default_annotations);
3280
3281 // Replace minor version number of class file
3282 u2 old_minor_version = the_class->minor_version();
3283 the_class->set_minor_version(scratch_class->minor_version());
3284 scratch_class->set_minor_version(old_minor_version);
3285
3286 // Replace major version number of class file
3287 u2 old_major_version = the_class->major_version();
3288 the_class->set_major_version(scratch_class->major_version());
3289 scratch_class->set_major_version(old_major_version);
3290
3291 // Replace CP indexes for class and name+type of enclosing method
3292 u2 old_class_idx = the_class->enclosing_method_class_index();
3293 u2 old_method_idx = the_class->enclosing_method_method_index();
3294 the_class->set_enclosing_method_indices(
3295 scratch_class->enclosing_method_class_index(),
3296 scratch_class->enclosing_method_method_index());
3297 scratch_class->set_enclosing_method_indices(old_class_idx, old_method_idx);
3298
3299 // keep track of previous versions of this class
3300 the_class->add_previous_version(scratch_class, &emcp_methods,
3301 emcp_method_count);
3302
3303 RC_TIMER_STOP(_timer_rsc_phase1);
3304 RC_TIMER_START(_timer_rsc_phase2);
3305
3306 // Adjust constantpool caches and vtables for all classes
3307 // that reference methods of the evolved class.
3308 SystemDictionary::classes_do(adjust_cpool_cache_and_vtable, THREAD);
3309
3310 if (the_class->oop_map_cache() != NULL) {
3311 // Flush references to any obsolete methods from the oop map cache
3312 // so that obsolete methods are not pinned.
3313 the_class->oop_map_cache()->flush_obsolete_entries();
3314 }
3315
3316 // increment the classRedefinedCount field in the_class and in any
3317 // direct and indirect subclasses of the_class
3318 increment_class_counter((instanceKlass *)the_class()->klass_part(), THREAD);
3319
3320 // RC_TRACE macro has an embedded ResourceMark
3321 RC_TRACE_WITH_THREAD(0x00000001, THREAD,
3322 ("redefined name=%s, count=%d (avail_mem=" UINT64_FORMAT "K)",
3323 the_class->external_name(),
3324 java_lang_Class::classRedefinedCount(the_class_mirror),
3325 os::available_memory() >> 10));
3326
3327 RC_TIMER_STOP(_timer_rsc_phase2);
3328 } // end redefine_single_class()
3329
3330
3331 // Increment the classRedefinedCount field in the specific instanceKlass
3332 // and in all direct and indirect subclasses.
3333 void VM_RedefineClasses::increment_class_counter(instanceKlass *ik, TRAPS) {
3334 oop class_mirror = ik->java_mirror();
3335 klassOop class_oop = java_lang_Class::as_klassOop(class_mirror);
3336 int new_count = java_lang_Class::classRedefinedCount(class_mirror) + 1;
3337 java_lang_Class::set_classRedefinedCount(class_mirror, new_count);
3338
3339 if (class_oop != _the_class_oop) {
3340 // _the_class_oop count is printed at end of redefine_single_class()
3341 RC_TRACE_WITH_THREAD(0x00000008, THREAD,
3342 ("updated count in subclass=%s to %d", ik->external_name(), new_count));
3343 }
3344
3345 for (Klass *subk = ik->subklass(); subk != NULL;
3346 subk = subk->next_sibling()) {
3347 if (subk->oop_is_instance()) {
3348 // Only update instanceKlasses
3349 instanceKlass *subik = (instanceKlass*)subk;
3350 // recursively do subclasses of the current subclass
3351 increment_class_counter(subik, THREAD);
3352 }
3353 }
3354 }
3355
3356 #ifndef PRODUCT
3357 void VM_RedefineClasses::check_class(klassOop k_oop,
3358 oop initiating_loader, TRAPS) {
3359 Klass *k = k_oop->klass_part();
3360 if (k->oop_is_instance()) {
3361 HandleMark hm(THREAD);
3362 instanceKlass *ik = (instanceKlass *) k;
3363
3364 if (ik->vtable_length() > 0) {
3365 ResourceMark rm(THREAD);
3366 if (!ik->vtable()->check_no_old_entries()) {
3367 tty->print_cr("klassVtable::check_no_old_entries failure -- OLD method found -- class: %s", ik->signature_name());
3368 ik->vtable()->dump_vtable();
3369 dump_methods();
3370 assert(false, "OLD method found");
3371 }
3372 }
3373 }
3374 }
3375
3376 void VM_RedefineClasses::dump_methods() {
3377 int j;
3378 tty->print_cr("_old_methods --");
3379 for (j = 0; j < _old_methods->length(); ++j) {
3380 methodOop m = (methodOop) _old_methods->obj_at(j);
3381 tty->print("%4d (%5d) ", j, m->vtable_index());
3382 m->access_flags().print_on(tty);
3383 tty->print(" -- ");
3384 m->print_name(tty);
3385 tty->cr();
3386 }
3387 tty->print_cr("_new_methods --");
3388 for (j = 0; j < _new_methods->length(); ++j) {
3389 methodOop m = (methodOop) _new_methods->obj_at(j);
3390 tty->print("%4d (%5d) ", j, m->vtable_index());
3391 m->access_flags().print_on(tty);
3392 tty->print(" -- ");
3393 m->print_name(tty);
3394 tty->cr();
3395 }
3396 tty->print_cr("_matching_(old/new)_methods --");
3397 for (j = 0; j < _matching_methods_length; ++j) {
3398 methodOop m = _matching_old_methods[j];
3399 tty->print("%4d (%5d) ", j, m->vtable_index());
3400 m->access_flags().print_on(tty);
3401 tty->print(" -- ");
3402 m->print_name(tty);
3403 tty->cr();
3404 m = _matching_new_methods[j];
3405 tty->print(" (%5d) ", m->vtable_index());
3406 m->access_flags().print_on(tty);
3407 tty->cr();
3408 }
3409 tty->print_cr("_deleted_methods --");
3410 for (j = 0; j < _deleted_methods_length; ++j) {
3411 methodOop m = _deleted_methods[j];
3412 tty->print("%4d (%5d) ", j, m->vtable_index());
3413 m->access_flags().print_on(tty);
3414 tty->print(" -- ");
3415 m->print_name(tty);
3416 tty->cr();
3417 }
3418 tty->print_cr("_added_methods --");
3419 for (j = 0; j < _added_methods_length; ++j) {
3420 methodOop m = _added_methods[j];
3421 tty->print("%4d (%5d) ", j, m->vtable_index());
3422 m->access_flags().print_on(tty);
3423 tty->print(" -- ");
3424 m->print_name(tty);
3425 tty->cr();
3426 }
3427 }
3428 #endif