1 /*
2 * Copyright (c) 2003, 2017, 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/metadataOnStackMark.hpp"
27 #include "classfile/systemDictionary.hpp"
28 #include "classfile/verifier.hpp"
29 #include "code/codeCache.hpp"
30 #include "compiler/compileBroker.hpp"
31 #include "interpreter/oopMapCache.hpp"
32 #include "interpreter/rewriter.hpp"
33 #include "memory/gcLocker.hpp"
34 #include "memory/metadataFactory.hpp"
35 #include "memory/metaspaceShared.hpp"
36 #include "memory/universe.inline.hpp"
37 #include "oops/fieldStreams.hpp"
38 #include "oops/klassVtable.hpp"
39 #include "prims/jvmtiImpl.hpp"
40 #include "prims/jvmtiRedefineClasses.hpp"
41 #include "prims/methodComparator.hpp"
42 #include "runtime/deoptimization.hpp"
43 #include "runtime/relocator.hpp"
44 #include "utilities/bitMap.inline.hpp"
45 #include "utilities/events.hpp"
46
47 PRAGMA_FORMAT_MUTE_WARNINGS_FOR_GCC
48
49 Array<Method*>* VM_RedefineClasses::_old_methods = NULL;
50 Array<Method*>* VM_RedefineClasses::_new_methods = NULL;
51 Method** VM_RedefineClasses::_matching_old_methods = NULL;
52 Method** VM_RedefineClasses::_matching_new_methods = NULL;
53 Method** VM_RedefineClasses::_deleted_methods = NULL;
54 Method** VM_RedefineClasses::_added_methods = NULL;
55 int VM_RedefineClasses::_matching_methods_length = 0;
56 int VM_RedefineClasses::_deleted_methods_length = 0;
57 int VM_RedefineClasses::_added_methods_length = 0;
58 Klass* VM_RedefineClasses::_the_class_oop = NULL;
59
60
VM_RedefineClasses(jint class_count,const jvmtiClassDefinition * class_defs,JvmtiClassLoadKind class_load_kind)61 VM_RedefineClasses::VM_RedefineClasses(jint class_count,
62 const jvmtiClassDefinition *class_defs,
63 JvmtiClassLoadKind class_load_kind) {
64 _class_count = class_count;
65 _class_defs = class_defs;
66 _class_load_kind = class_load_kind;
67 _res = JVMTI_ERROR_NONE;
68 }
69
get_ik(jclass def)70 static inline InstanceKlass* get_ik(jclass def) {
71 oop mirror = JNIHandles::resolve_non_null(def);
72 return InstanceKlass::cast(java_lang_Class::as_Klass(mirror));
73 }
74
75 // If any of the classes are being redefined, wait
76 // Parallel constant pool merging leads to indeterminate constant pools.
lock_classes()77 void VM_RedefineClasses::lock_classes() {
78 MutexLocker ml(RedefineClasses_lock);
79 bool has_redefined;
80 do {
81 has_redefined = false;
82 // Go through classes each time until none are being redefined.
83 for (int i = 0; i < _class_count; i++) {
84 if (get_ik(_class_defs[i].klass)->is_being_redefined()) {
85 RedefineClasses_lock->wait();
86 has_redefined = true;
87 break; // for loop
88 }
89 }
90 } while (has_redefined);
91 for (int i = 0; i < _class_count; i++) {
92 get_ik(_class_defs[i].klass)->set_is_being_redefined(true);
93 }
94 RedefineClasses_lock->notify_all();
95 }
96
unlock_classes()97 void VM_RedefineClasses::unlock_classes() {
98 MutexLocker ml(RedefineClasses_lock);
99 for (int i = 0; i < _class_count; i++) {
100 assert(get_ik(_class_defs[i].klass)->is_being_redefined(),
101 "should be being redefined to get here");
102 get_ik(_class_defs[i].klass)->set_is_being_redefined(false);
103 }
104 RedefineClasses_lock->notify_all();
105 }
106
doit_prologue()107 bool VM_RedefineClasses::doit_prologue() {
108 if (_class_count == 0) {
109 _res = JVMTI_ERROR_NONE;
110 return false;
111 }
112 if (_class_defs == NULL) {
113 _res = JVMTI_ERROR_NULL_POINTER;
114 return false;
115 }
116 for (int i = 0; i < _class_count; i++) {
117 if (_class_defs[i].klass == NULL) {
118 _res = JVMTI_ERROR_INVALID_CLASS;
119 return false;
120 }
121 if (_class_defs[i].class_byte_count == 0) {
122 _res = JVMTI_ERROR_INVALID_CLASS_FORMAT;
123 return false;
124 }
125 if (_class_defs[i].class_bytes == NULL) {
126 _res = JVMTI_ERROR_NULL_POINTER;
127 return false;
128 }
129
130 oop mirror = JNIHandles::resolve_non_null(_class_defs[i].klass);
131 // classes for primitives and arrays cannot be redefined
132 // check here so following code can assume these classes are InstanceKlass
133 if (!is_modifiable_class(mirror)) {
134 _res = JVMTI_ERROR_UNMODIFIABLE_CLASS;
135 return false;
136 }
137 }
138
139 // Start timer after all the sanity checks; not quite accurate, but
140 // better than adding a bunch of stop() calls.
141 RC_TIMER_START(_timer_vm_op_prologue);
142
143 lock_classes();
144 // We first load new class versions in the prologue, because somewhere down the
145 // call chain it is required that the current thread is a Java thread.
146 _res = load_new_class_versions(Thread::current());
147 if (_res != JVMTI_ERROR_NONE) {
148 // free any successfully created classes, since none are redefined
149 for (int i = 0; i < _class_count; i++) {
150 if (_scratch_classes[i] != NULL) {
151 ClassLoaderData* cld = _scratch_classes[i]->class_loader_data();
152 // Free the memory for this class at class unloading time. Not before
153 // because CMS might think this is still live.
154 InstanceKlass* ik = get_ik(_class_defs[i].klass);
155 if (ik->get_cached_class_file() == ((InstanceKlass*)_scratch_classes[i])->get_cached_class_file()) {
156 // Don't double-free cached_class_file copied from the original class if error.
157 ((InstanceKlass*)_scratch_classes[i])->set_cached_class_file(NULL);
158 }
159 cld->add_to_deallocate_list((InstanceKlass*)_scratch_classes[i]);
160 }
161 }
162 // Free os::malloc allocated memory in load_new_class_version.
163 os::free(_scratch_classes);
164 RC_TIMER_STOP(_timer_vm_op_prologue);
165 unlock_classes();
166 return false;
167 }
168
169 RC_TIMER_STOP(_timer_vm_op_prologue);
170 return true;
171 }
172
doit()173 void VM_RedefineClasses::doit() {
174 Thread *thread = Thread::current();
175
176 if (UseSharedSpaces) {
177 // Sharing is enabled so we remap the shared readonly space to
178 // shared readwrite, private just in case we need to redefine
179 // a shared class. We do the remap during the doit() phase of
180 // the safepoint to be safer.
181 if (!MetaspaceShared::remap_shared_readonly_as_readwrite()) {
182 RC_TRACE_WITH_THREAD(0x00000001, thread,
183 ("failed to remap shared readonly space to readwrite, private"));
184 _res = JVMTI_ERROR_INTERNAL;
185 return;
186 }
187 }
188
189 // Mark methods seen on stack and everywhere else so old methods are not
190 // cleaned up if they're on the stack.
191 MetadataOnStackMark md_on_stack(true);
192 HandleMark hm(thread); // make sure any handles created are deleted
193 // before the stack walk again.
194
195 for (int i = 0; i < _class_count; i++) {
196 redefine_single_class(_class_defs[i].klass, _scratch_classes[i], thread);
197 ClassLoaderData* cld = _scratch_classes[i]->class_loader_data();
198 // Free the memory for this class at class unloading time. Not before
199 // because CMS might think this is still live.
200 cld->add_to_deallocate_list((InstanceKlass*)_scratch_classes[i]);
201 _scratch_classes[i] = NULL;
202 }
203
204 // Disable any dependent concurrent compilations
205 SystemDictionary::notice_modification();
206
207 // Set flag indicating that some invariants are no longer true.
208 // See jvmtiExport.hpp for detailed explanation.
209 JvmtiExport::set_has_redefined_a_class();
210
211 // check_class() is optionally called for product bits, but is
212 // always called for non-product bits.
213 #ifdef PRODUCT
214 if (RC_TRACE_ENABLED(0x00004000)) {
215 #endif
216 RC_TRACE_WITH_THREAD(0x00004000, thread, ("calling check_class"));
217 CheckClass check_class(thread);
218 ClassLoaderDataGraph::classes_do(&check_class);
219 #ifdef PRODUCT
220 }
221 #endif
222 }
223
doit_epilogue()224 void VM_RedefineClasses::doit_epilogue() {
225 unlock_classes();
226
227 // Free os::malloc allocated memory.
228 os::free(_scratch_classes);
229
230 // Reset the_class_oop to null for error printing.
231 _the_class_oop = NULL;
232
233 if (RC_TRACE_ENABLED(0x00000004)) {
234 // Used to have separate timers for "doit" and "all", but the timer
235 // overhead skewed the measurements.
236 jlong doit_time = _timer_rsc_phase1.milliseconds() +
237 _timer_rsc_phase2.milliseconds();
238 jlong all_time = _timer_vm_op_prologue.milliseconds() + doit_time;
239
240 RC_TRACE(0x00000004, ("vm_op: all=" UINT64_FORMAT
241 " prologue=" UINT64_FORMAT " doit=" UINT64_FORMAT, all_time,
242 _timer_vm_op_prologue.milliseconds(), doit_time));
243 RC_TRACE(0x00000004,
244 ("redefine_single_class: phase1=" UINT64_FORMAT " phase2=" UINT64_FORMAT,
245 _timer_rsc_phase1.milliseconds(), _timer_rsc_phase2.milliseconds()));
246 }
247 }
248
is_modifiable_class(oop klass_mirror)249 bool VM_RedefineClasses::is_modifiable_class(oop klass_mirror) {
250 // classes for primitives cannot be redefined
251 if (java_lang_Class::is_primitive(klass_mirror)) {
252 return false;
253 }
254 Klass* the_class_oop = java_lang_Class::as_Klass(klass_mirror);
255 // classes for arrays cannot be redefined
256 if (the_class_oop == NULL || !the_class_oop->oop_is_instance()) {
257 return false;
258 }
259 return true;
260 }
261
262 // Append the current entry at scratch_i in scratch_cp to *merge_cp_p
263 // where the end of *merge_cp_p is specified by *merge_cp_length_p. For
264 // direct CP entries, there is just the current entry to append. For
265 // indirect and double-indirect CP entries, there are zero or more
266 // referenced CP entries along with the current entry to append.
267 // Indirect and double-indirect CP entries are handled by recursive
268 // calls to append_entry() as needed. The referenced CP entries are
269 // always appended to *merge_cp_p before the referee CP entry. These
270 // referenced CP entries may already exist in *merge_cp_p in which case
271 // there is nothing extra to append and only the current entry is
272 // appended.
append_entry(constantPoolHandle scratch_cp,int scratch_i,constantPoolHandle * merge_cp_p,int * merge_cp_length_p,TRAPS)273 void VM_RedefineClasses::append_entry(constantPoolHandle scratch_cp,
274 int scratch_i, constantPoolHandle *merge_cp_p, int *merge_cp_length_p,
275 TRAPS) {
276
277 // append is different depending on entry tag type
278 switch (scratch_cp->tag_at(scratch_i).value()) {
279
280 // The old verifier is implemented outside the VM. It loads classes,
281 // but does not resolve constant pool entries directly so we never
282 // see Class entries here with the old verifier. Similarly the old
283 // verifier does not like Class entries in the input constant pool.
284 // The split-verifier is implemented in the VM so it can optionally
285 // and directly resolve constant pool entries to load classes. The
286 // split-verifier can accept either Class entries or UnresolvedClass
287 // entries in the input constant pool. We revert the appended copy
288 // back to UnresolvedClass so that either verifier will be happy
289 // with the constant pool entry.
290 case JVM_CONSTANT_Class:
291 {
292 // revert the copy to JVM_CONSTANT_UnresolvedClass
293 (*merge_cp_p)->unresolved_klass_at_put(*merge_cp_length_p,
294 scratch_cp->klass_name_at(scratch_i));
295
296 if (scratch_i != *merge_cp_length_p) {
297 // The new entry in *merge_cp_p is at a different index than
298 // the new entry in scratch_cp so we need to map the index values.
299 map_index(scratch_cp, scratch_i, *merge_cp_length_p);
300 }
301 (*merge_cp_length_p)++;
302 } break;
303
304 // these are direct CP entries so they can be directly appended,
305 // but double and long take two constant pool entries
306 case JVM_CONSTANT_Double: // fall through
307 case JVM_CONSTANT_Long:
308 {
309 ConstantPool::copy_entry_to(scratch_cp, scratch_i, *merge_cp_p, *merge_cp_length_p,
310 THREAD);
311
312 if (scratch_i != *merge_cp_length_p) {
313 // The new entry in *merge_cp_p is at a different index than
314 // the new entry in scratch_cp so we need to map the index values.
315 map_index(scratch_cp, scratch_i, *merge_cp_length_p);
316 }
317 (*merge_cp_length_p) += 2;
318 } break;
319
320 // these are direct CP entries so they can be directly appended
321 case JVM_CONSTANT_Float: // fall through
322 case JVM_CONSTANT_Integer: // fall through
323 case JVM_CONSTANT_Utf8: // fall through
324
325 // This was an indirect CP entry, but it has been changed into
326 // Symbol*s so this entry can be directly appended.
327 case JVM_CONSTANT_String: // fall through
328
329 // These were indirect CP entries, but they have been changed into
330 // Symbol*s so these entries can be directly appended.
331 case JVM_CONSTANT_UnresolvedClass: // fall through
332 {
333 ConstantPool::copy_entry_to(scratch_cp, scratch_i, *merge_cp_p, *merge_cp_length_p,
334 THREAD);
335
336 if (scratch_i != *merge_cp_length_p) {
337 // The new entry in *merge_cp_p is at a different index than
338 // the new entry in scratch_cp so we need to map the index values.
339 map_index(scratch_cp, scratch_i, *merge_cp_length_p);
340 }
341 (*merge_cp_length_p)++;
342 } break;
343
344 // this is an indirect CP entry so it needs special handling
345 case JVM_CONSTANT_NameAndType:
346 {
347 int name_ref_i = scratch_cp->name_ref_index_at(scratch_i);
348 int new_name_ref_i = find_or_append_indirect_entry(scratch_cp, name_ref_i, merge_cp_p,
349 merge_cp_length_p, THREAD);
350
351 int signature_ref_i = scratch_cp->signature_ref_index_at(scratch_i);
352 int new_signature_ref_i = find_or_append_indirect_entry(scratch_cp, signature_ref_i,
353 merge_cp_p, merge_cp_length_p,
354 THREAD);
355
356 // If the referenced entries already exist in *merge_cp_p, then
357 // both new_name_ref_i and new_signature_ref_i will both be 0.
358 // In that case, all we are appending is the current entry.
359 if (new_name_ref_i != name_ref_i) {
360 RC_TRACE(0x00080000,
361 ("NameAndType entry@%d name_ref_index change: %d to %d",
362 *merge_cp_length_p, name_ref_i, new_name_ref_i));
363 }
364 if (new_signature_ref_i != signature_ref_i) {
365 RC_TRACE(0x00080000,
366 ("NameAndType entry@%d signature_ref_index change: %d to %d",
367 *merge_cp_length_p, signature_ref_i, new_signature_ref_i));
368 }
369
370 (*merge_cp_p)->name_and_type_at_put(*merge_cp_length_p,
371 new_name_ref_i, new_signature_ref_i);
372 if (scratch_i != *merge_cp_length_p) {
373 // The new entry in *merge_cp_p is at a different index than
374 // the new entry in scratch_cp so we need to map the index values.
375 map_index(scratch_cp, scratch_i, *merge_cp_length_p);
376 }
377 (*merge_cp_length_p)++;
378 } break;
379
380 // this is a double-indirect CP entry so it needs special handling
381 case JVM_CONSTANT_Fieldref: // fall through
382 case JVM_CONSTANT_InterfaceMethodref: // fall through
383 case JVM_CONSTANT_Methodref:
384 {
385 int klass_ref_i = scratch_cp->uncached_klass_ref_index_at(scratch_i);
386 int new_klass_ref_i = find_or_append_indirect_entry(scratch_cp, klass_ref_i,
387 merge_cp_p, merge_cp_length_p, THREAD);
388
389 int name_and_type_ref_i = scratch_cp->uncached_name_and_type_ref_index_at(scratch_i);
390 int new_name_and_type_ref_i = find_or_append_indirect_entry(scratch_cp, name_and_type_ref_i,
391 merge_cp_p, merge_cp_length_p, THREAD);
392
393 const char *entry_name = NULL;
394 switch (scratch_cp->tag_at(scratch_i).value()) {
395 case JVM_CONSTANT_Fieldref:
396 entry_name = "Fieldref";
397 (*merge_cp_p)->field_at_put(*merge_cp_length_p, new_klass_ref_i,
398 new_name_and_type_ref_i);
399 break;
400 case JVM_CONSTANT_InterfaceMethodref:
401 entry_name = "IFMethodref";
402 (*merge_cp_p)->interface_method_at_put(*merge_cp_length_p,
403 new_klass_ref_i, new_name_and_type_ref_i);
404 break;
405 case JVM_CONSTANT_Methodref:
406 entry_name = "Methodref";
407 (*merge_cp_p)->method_at_put(*merge_cp_length_p, new_klass_ref_i,
408 new_name_and_type_ref_i);
409 break;
410 default:
411 guarantee(false, "bad switch");
412 break;
413 }
414
415 if (klass_ref_i != new_klass_ref_i) {
416 RC_TRACE(0x00080000, ("%s entry@%d class_index changed: %d to %d",
417 entry_name, *merge_cp_length_p, klass_ref_i, new_klass_ref_i));
418 }
419 if (name_and_type_ref_i != new_name_and_type_ref_i) {
420 RC_TRACE(0x00080000,
421 ("%s entry@%d name_and_type_index changed: %d to %d",
422 entry_name, *merge_cp_length_p, name_and_type_ref_i,
423 new_name_and_type_ref_i));
424 }
425
426 if (scratch_i != *merge_cp_length_p) {
427 // The new entry in *merge_cp_p is at a different index than
428 // the new entry in scratch_cp so we need to map the index values.
429 map_index(scratch_cp, scratch_i, *merge_cp_length_p);
430 }
431 (*merge_cp_length_p)++;
432 } break;
433
434 // this is an indirect CP entry so it needs special handling
435 case JVM_CONSTANT_MethodType:
436 {
437 int ref_i = scratch_cp->method_type_index_at(scratch_i);
438 int new_ref_i = find_or_append_indirect_entry(scratch_cp, ref_i, merge_cp_p,
439 merge_cp_length_p, THREAD);
440 if (new_ref_i != ref_i) {
441 RC_TRACE(0x00080000,
442 ("MethodType entry@%d ref_index change: %d to %d",
443 *merge_cp_length_p, ref_i, new_ref_i));
444 }
445 (*merge_cp_p)->method_type_index_at_put(*merge_cp_length_p, new_ref_i);
446 if (scratch_i != *merge_cp_length_p) {
447 // The new entry in *merge_cp_p is at a different index than
448 // the new entry in scratch_cp so we need to map the index values.
449 map_index(scratch_cp, scratch_i, *merge_cp_length_p);
450 }
451 (*merge_cp_length_p)++;
452 } break;
453
454 // this is an indirect CP entry so it needs special handling
455 case JVM_CONSTANT_MethodHandle:
456 {
457 int ref_kind = scratch_cp->method_handle_ref_kind_at(scratch_i);
458 int ref_i = scratch_cp->method_handle_index_at(scratch_i);
459 int new_ref_i = find_or_append_indirect_entry(scratch_cp, ref_i, merge_cp_p,
460 merge_cp_length_p, THREAD);
461 if (new_ref_i != ref_i) {
462 RC_TRACE(0x00080000,
463 ("MethodHandle entry@%d ref_index change: %d to %d",
464 *merge_cp_length_p, ref_i, new_ref_i));
465 }
466 (*merge_cp_p)->method_handle_index_at_put(*merge_cp_length_p, ref_kind, new_ref_i);
467 if (scratch_i != *merge_cp_length_p) {
468 // The new entry in *merge_cp_p is at a different index than
469 // the new entry in scratch_cp so we need to map the index values.
470 map_index(scratch_cp, scratch_i, *merge_cp_length_p);
471 }
472 (*merge_cp_length_p)++;
473 } break;
474
475 // this is an indirect CP entry so it needs special handling
476 case JVM_CONSTANT_InvokeDynamic:
477 {
478 // Index of the bootstrap specifier in the operands array
479 int old_bs_i = scratch_cp->invoke_dynamic_bootstrap_specifier_index(scratch_i);
480 int new_bs_i = find_or_append_operand(scratch_cp, old_bs_i, merge_cp_p,
481 merge_cp_length_p, THREAD);
482 // The bootstrap method NameAndType_info index
483 int old_ref_i = scratch_cp->invoke_dynamic_name_and_type_ref_index_at(scratch_i);
484 int new_ref_i = find_or_append_indirect_entry(scratch_cp, old_ref_i, merge_cp_p,
485 merge_cp_length_p, THREAD);
486 if (new_bs_i != old_bs_i) {
487 RC_TRACE(0x00080000,
488 ("InvokeDynamic entry@%d bootstrap_method_attr_index change: %d to %d",
489 *merge_cp_length_p, old_bs_i, new_bs_i));
490 }
491 if (new_ref_i != old_ref_i) {
492 RC_TRACE(0x00080000,
493 ("InvokeDynamic entry@%d name_and_type_index change: %d to %d",
494 *merge_cp_length_p, old_ref_i, new_ref_i));
495 }
496
497 (*merge_cp_p)->invoke_dynamic_at_put(*merge_cp_length_p, new_bs_i, new_ref_i);
498 if (scratch_i != *merge_cp_length_p) {
499 // The new entry in *merge_cp_p is at a different index than
500 // the new entry in scratch_cp so we need to map the index values.
501 map_index(scratch_cp, scratch_i, *merge_cp_length_p);
502 }
503 (*merge_cp_length_p)++;
504 } break;
505
506 // At this stage, Class or UnresolvedClass could be here, but not
507 // ClassIndex
508 case JVM_CONSTANT_ClassIndex: // fall through
509
510 // Invalid is used as the tag for the second constant pool entry
511 // occupied by JVM_CONSTANT_Double or JVM_CONSTANT_Long. It should
512 // not be seen by itself.
513 case JVM_CONSTANT_Invalid: // fall through
514
515 // At this stage, String could be here, but not StringIndex
516 case JVM_CONSTANT_StringIndex: // fall through
517
518 // At this stage JVM_CONSTANT_UnresolvedClassInError should not be
519 // here
520 case JVM_CONSTANT_UnresolvedClassInError: // fall through
521
522 default:
523 {
524 // leave a breadcrumb
525 jbyte bad_value = scratch_cp->tag_at(scratch_i).value();
526 ShouldNotReachHere();
527 } break;
528 } // end switch tag value
529 } // end append_entry()
530
531
find_or_append_indirect_entry(constantPoolHandle scratch_cp,int ref_i,constantPoolHandle * merge_cp_p,int * merge_cp_length_p,TRAPS)532 int VM_RedefineClasses::find_or_append_indirect_entry(constantPoolHandle scratch_cp,
533 int ref_i, constantPoolHandle *merge_cp_p, int *merge_cp_length_p, TRAPS) {
534
535 int new_ref_i = ref_i;
536 bool match = (ref_i < *merge_cp_length_p) &&
537 scratch_cp->compare_entry_to(ref_i, *merge_cp_p, ref_i, THREAD);
538
539 if (!match) {
540 // forward reference in *merge_cp_p or not a direct match
541 int found_i = scratch_cp->find_matching_entry(ref_i, *merge_cp_p, THREAD);
542 if (found_i != 0) {
543 guarantee(found_i != ref_i, "compare_entry_to() and find_matching_entry() do not agree");
544 // Found a matching entry somewhere else in *merge_cp_p so just need a mapping entry.
545 new_ref_i = found_i;
546 map_index(scratch_cp, ref_i, found_i);
547 } else {
548 // no match found so we have to append this entry to *merge_cp_p
549 append_entry(scratch_cp, ref_i, merge_cp_p, merge_cp_length_p, THREAD);
550 // The above call to append_entry() can only append one entry
551 // so the post call query of *merge_cp_length_p is only for
552 // the sake of consistency.
553 new_ref_i = *merge_cp_length_p - 1;
554 }
555 }
556
557 return new_ref_i;
558 } // end find_or_append_indirect_entry()
559
560
561 // Append a bootstrap specifier into the merge_cp operands that is semantically equal
562 // to the scratch_cp operands bootstrap specifier passed by the old_bs_i index.
563 // Recursively append new merge_cp entries referenced by the new bootstrap specifier.
append_operand(constantPoolHandle scratch_cp,int old_bs_i,constantPoolHandle * merge_cp_p,int * merge_cp_length_p,TRAPS)564 void VM_RedefineClasses::append_operand(constantPoolHandle scratch_cp, int old_bs_i,
565 constantPoolHandle *merge_cp_p, int *merge_cp_length_p, TRAPS) {
566
567 int old_ref_i = scratch_cp->operand_bootstrap_method_ref_index_at(old_bs_i);
568 int new_ref_i = find_or_append_indirect_entry(scratch_cp, old_ref_i, merge_cp_p,
569 merge_cp_length_p, THREAD);
570 if (new_ref_i != old_ref_i) {
571 RC_TRACE(0x00080000,
572 ("operands entry@%d bootstrap method ref_index change: %d to %d",
573 _operands_cur_length, old_ref_i, new_ref_i));
574 }
575
576 Array<u2>* merge_ops = (*merge_cp_p)->operands();
577 int new_bs_i = _operands_cur_length;
578 // We have _operands_cur_length == 0 when the merge_cp operands is empty yet.
579 // However, the operand_offset_at(0) was set in the extend_operands() call.
580 int new_base = (new_bs_i == 0) ? (*merge_cp_p)->operand_offset_at(0)
581 : (*merge_cp_p)->operand_next_offset_at(new_bs_i - 1);
582 int argc = scratch_cp->operand_argument_count_at(old_bs_i);
583
584 ConstantPool::operand_offset_at_put(merge_ops, _operands_cur_length, new_base);
585 merge_ops->at_put(new_base++, new_ref_i);
586 merge_ops->at_put(new_base++, argc);
587
588 for (int i = 0; i < argc; i++) {
589 int old_arg_ref_i = scratch_cp->operand_argument_index_at(old_bs_i, i);
590 int new_arg_ref_i = find_or_append_indirect_entry(scratch_cp, old_arg_ref_i, merge_cp_p,
591 merge_cp_length_p, THREAD);
592 merge_ops->at_put(new_base++, new_arg_ref_i);
593 if (new_arg_ref_i != old_arg_ref_i) {
594 RC_TRACE(0x00080000,
595 ("operands entry@%d bootstrap method argument ref_index change: %d to %d",
596 _operands_cur_length, old_arg_ref_i, new_arg_ref_i));
597 }
598 }
599 if (old_bs_i != _operands_cur_length) {
600 // The bootstrap specifier in *merge_cp_p is at a different index than
601 // that in scratch_cp so we need to map the index values.
602 map_operand_index(old_bs_i, new_bs_i);
603 }
604 _operands_cur_length++;
605 } // end append_operand()
606
607
find_or_append_operand(constantPoolHandle scratch_cp,int old_bs_i,constantPoolHandle * merge_cp_p,int * merge_cp_length_p,TRAPS)608 int VM_RedefineClasses::find_or_append_operand(constantPoolHandle scratch_cp,
609 int old_bs_i, constantPoolHandle *merge_cp_p, int *merge_cp_length_p, TRAPS) {
610
611 int new_bs_i = old_bs_i; // bootstrap specifier index
612 bool match = (old_bs_i < _operands_cur_length) &&
613 scratch_cp->compare_operand_to(old_bs_i, *merge_cp_p, old_bs_i, THREAD);
614
615 if (!match) {
616 // forward reference in *merge_cp_p or not a direct match
617 int found_i = scratch_cp->find_matching_operand(old_bs_i, *merge_cp_p,
618 _operands_cur_length, THREAD);
619 if (found_i != -1) {
620 guarantee(found_i != old_bs_i, "compare_operand_to() and find_matching_operand() disagree");
621 // found a matching operand somewhere else in *merge_cp_p so just need a mapping
622 new_bs_i = found_i;
623 map_operand_index(old_bs_i, found_i);
624 } else {
625 // no match found so we have to append this bootstrap specifier to *merge_cp_p
626 append_operand(scratch_cp, old_bs_i, merge_cp_p, merge_cp_length_p, THREAD);
627 new_bs_i = _operands_cur_length - 1;
628 }
629 }
630 return new_bs_i;
631 } // end find_or_append_operand()
632
633
finalize_operands_merge(constantPoolHandle merge_cp,TRAPS)634 void VM_RedefineClasses::finalize_operands_merge(constantPoolHandle merge_cp, TRAPS) {
635 if (merge_cp->operands() == NULL) {
636 return;
637 }
638 // Shrink the merge_cp operands
639 merge_cp->shrink_operands(_operands_cur_length, CHECK);
640
641 if (RC_TRACE_ENABLED(0x00040000)) {
642 // don't want to loop unless we are tracing
643 int count = 0;
644 for (int i = 1; i < _operands_index_map_p->length(); i++) {
645 int value = _operands_index_map_p->at(i);
646 if (value != -1) {
647 RC_TRACE_WITH_THREAD(0x00040000, THREAD,
648 ("operands_index_map[%d]: old=%d new=%d", count, i, value));
649 count++;
650 }
651 }
652 }
653 // Clean-up
654 _operands_index_map_p = NULL;
655 _operands_cur_length = 0;
656 _operands_index_map_count = 0;
657 } // end finalize_operands_merge()
658
659
compare_and_normalize_class_versions(instanceKlassHandle the_class,instanceKlassHandle scratch_class)660 jvmtiError VM_RedefineClasses::compare_and_normalize_class_versions(
661 instanceKlassHandle the_class,
662 instanceKlassHandle scratch_class) {
663 int i;
664
665 // Check superclasses, or rather their names, since superclasses themselves can be
666 // requested to replace.
667 // Check for NULL superclass first since this might be java.lang.Object
668 if (the_class->super() != scratch_class->super() &&
669 (the_class->super() == NULL || scratch_class->super() == NULL ||
670 the_class->super()->name() !=
671 scratch_class->super()->name())) {
672 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_HIERARCHY_CHANGED;
673 }
674
675 // Check if the number, names and order of directly implemented interfaces are the same.
676 // I think in principle we should just check if the sets of names of directly implemented
677 // interfaces are the same, i.e. the order of declaration (which, however, if changed in the
678 // .java file, also changes in .class file) should not matter. However, comparing sets is
679 // technically a bit more difficult, and, more importantly, I am not sure at present that the
680 // order of interfaces does not matter on the implementation level, i.e. that the VM does not
681 // rely on it somewhere.
682 Array<Klass*>* k_interfaces = the_class->local_interfaces();
683 Array<Klass*>* k_new_interfaces = scratch_class->local_interfaces();
684 int n_intfs = k_interfaces->length();
685 if (n_intfs != k_new_interfaces->length()) {
686 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_HIERARCHY_CHANGED;
687 }
688 for (i = 0; i < n_intfs; i++) {
689 if (k_interfaces->at(i)->name() !=
690 k_new_interfaces->at(i)->name()) {
691 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_HIERARCHY_CHANGED;
692 }
693 }
694
695 // Check whether class is in the error init state.
696 if (the_class->is_in_error_state()) {
697 // TBD #5057930: special error code is needed in 1.6
698 return JVMTI_ERROR_INVALID_CLASS;
699 }
700
701 // Check whether class modifiers are the same.
702 jushort old_flags = (jushort) the_class->access_flags().get_flags();
703 jushort new_flags = (jushort) scratch_class->access_flags().get_flags();
704 if (old_flags != new_flags) {
705 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_CLASS_MODIFIERS_CHANGED;
706 }
707
708 // Check if the number, names, types and order of fields declared in these classes
709 // are the same.
710 JavaFieldStream old_fs(the_class);
711 JavaFieldStream new_fs(scratch_class);
712 for (; !old_fs.done() && !new_fs.done(); old_fs.next(), new_fs.next()) {
713 // access
714 old_flags = old_fs.access_flags().as_short();
715 new_flags = new_fs.access_flags().as_short();
716 if ((old_flags ^ new_flags) & JVM_RECOGNIZED_FIELD_MODIFIERS) {
717 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_SCHEMA_CHANGED;
718 }
719 // offset
720 if (old_fs.offset() != new_fs.offset()) {
721 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_SCHEMA_CHANGED;
722 }
723 // name and signature
724 Symbol* name_sym1 = the_class->constants()->symbol_at(old_fs.name_index());
725 Symbol* sig_sym1 = the_class->constants()->symbol_at(old_fs.signature_index());
726 Symbol* name_sym2 = scratch_class->constants()->symbol_at(new_fs.name_index());
727 Symbol* sig_sym2 = scratch_class->constants()->symbol_at(new_fs.signature_index());
728 if (name_sym1 != name_sym2 || sig_sym1 != sig_sym2) {
729 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_SCHEMA_CHANGED;
730 }
731 }
732
733 // If both streams aren't done then we have a differing number of
734 // fields.
735 if (!old_fs.done() || !new_fs.done()) {
736 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_SCHEMA_CHANGED;
737 }
738
739 // Do a parallel walk through the old and new methods. Detect
740 // cases where they match (exist in both), have been added in
741 // the new methods, or have been deleted (exist only in the
742 // old methods). The class file parser places methods in order
743 // by method name, but does not order overloaded methods by
744 // signature. In order to determine what fate befell the methods,
745 // this code places the overloaded new methods that have matching
746 // old methods in the same order as the old methods and places
747 // new overloaded methods at the end of overloaded methods of
748 // that name. The code for this order normalization is adapted
749 // from the algorithm used in InstanceKlass::find_method().
750 // Since we are swapping out of order entries as we find them,
751 // we only have to search forward through the overloaded methods.
752 // Methods which are added and have the same name as an existing
753 // method (but different signature) will be put at the end of
754 // the methods with that name, and the name mismatch code will
755 // handle them.
756 Array<Method*>* k_old_methods(the_class->methods());
757 Array<Method*>* k_new_methods(scratch_class->methods());
758 int n_old_methods = k_old_methods->length();
759 int n_new_methods = k_new_methods->length();
760 Thread* thread = Thread::current();
761
762 int ni = 0;
763 int oi = 0;
764 while (true) {
765 Method* k_old_method;
766 Method* k_new_method;
767 enum { matched, added, deleted, undetermined } method_was = undetermined;
768
769 if (oi >= n_old_methods) {
770 if (ni >= n_new_methods) {
771 break; // we've looked at everything, done
772 }
773 // New method at the end
774 k_new_method = k_new_methods->at(ni);
775 method_was = added;
776 } else if (ni >= n_new_methods) {
777 // Old method, at the end, is deleted
778 k_old_method = k_old_methods->at(oi);
779 method_was = deleted;
780 } else {
781 // There are more methods in both the old and new lists
782 k_old_method = k_old_methods->at(oi);
783 k_new_method = k_new_methods->at(ni);
784 if (k_old_method->name() != k_new_method->name()) {
785 // Methods are sorted by method name, so a mismatch means added
786 // or deleted
787 if (k_old_method->name()->fast_compare(k_new_method->name()) > 0) {
788 method_was = added;
789 } else {
790 method_was = deleted;
791 }
792 } else if (k_old_method->signature() == k_new_method->signature()) {
793 // Both the name and signature match
794 method_was = matched;
795 } else {
796 // The name matches, but the signature doesn't, which means we have to
797 // search forward through the new overloaded methods.
798 int nj; // outside the loop for post-loop check
799 for (nj = ni + 1; nj < n_new_methods; nj++) {
800 Method* m = k_new_methods->at(nj);
801 if (k_old_method->name() != m->name()) {
802 // reached another method name so no more overloaded methods
803 method_was = deleted;
804 break;
805 }
806 if (k_old_method->signature() == m->signature()) {
807 // found a match so swap the methods
808 k_new_methods->at_put(ni, m);
809 k_new_methods->at_put(nj, k_new_method);
810 k_new_method = m;
811 method_was = matched;
812 break;
813 }
814 }
815
816 if (nj >= n_new_methods) {
817 // reached the end without a match; so method was deleted
818 method_was = deleted;
819 }
820 }
821 }
822
823 switch (method_was) {
824 case matched:
825 // methods match, be sure modifiers do too
826 old_flags = (jushort) k_old_method->access_flags().get_flags();
827 new_flags = (jushort) k_new_method->access_flags().get_flags();
828 if ((old_flags ^ new_flags) & ~(JVM_ACC_NATIVE)) {
829 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_METHOD_MODIFIERS_CHANGED;
830 }
831 {
832 u2 new_num = k_new_method->method_idnum();
833 u2 old_num = k_old_method->method_idnum();
834 if (new_num != old_num) {
835 Method* idnum_owner = scratch_class->method_with_idnum(old_num);
836 if (idnum_owner != NULL) {
837 // There is already a method assigned this idnum -- switch them
838 // Take current and original idnum from the new_method
839 idnum_owner->set_method_idnum(new_num);
840 idnum_owner->set_orig_method_idnum(k_new_method->orig_method_idnum());
841 }
842 // Take current and original idnum from the old_method
843 k_new_method->set_method_idnum(old_num);
844 k_new_method->set_orig_method_idnum(k_old_method->orig_method_idnum());
845 if (thread->has_pending_exception()) {
846 return JVMTI_ERROR_OUT_OF_MEMORY;
847 }
848 }
849 }
850 RC_TRACE(0x00008000, ("Method matched: new: %s [%d] == old: %s [%d]",
851 k_new_method->name_and_sig_as_C_string(), ni,
852 k_old_method->name_and_sig_as_C_string(), oi));
853 // advance to next pair of methods
854 ++oi;
855 ++ni;
856 break;
857 case added:
858 // method added, see if it is OK
859 new_flags = (jushort) k_new_method->access_flags().get_flags();
860 if ((new_flags & JVM_ACC_PRIVATE) == 0
861 // hack: private should be treated as final, but alas
862 || (new_flags & (JVM_ACC_FINAL|JVM_ACC_STATIC)) == 0
863 ) {
864 // new methods must be private
865 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_METHOD_ADDED;
866 }
867 {
868 u2 num = the_class->next_method_idnum();
869 if (num == ConstMethod::UNSET_IDNUM) {
870 // cannot add any more methods
871 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_METHOD_ADDED;
872 }
873 u2 new_num = k_new_method->method_idnum();
874 Method* idnum_owner = scratch_class->method_with_idnum(num);
875 if (idnum_owner != NULL) {
876 // There is already a method assigned this idnum -- switch them
877 // Take current and original idnum from the new_method
878 idnum_owner->set_method_idnum(new_num);
879 idnum_owner->set_orig_method_idnum(k_new_method->orig_method_idnum());
880 }
881 k_new_method->set_method_idnum(num);
882 k_new_method->set_orig_method_idnum(num);
883 if (thread->has_pending_exception()) {
884 return JVMTI_ERROR_OUT_OF_MEMORY;
885 }
886 }
887 RC_TRACE(0x00008000, ("Method added: new: %s [%d]",
888 k_new_method->name_and_sig_as_C_string(), ni));
889 ++ni; // advance to next new method
890 break;
891 case deleted:
892 // method deleted, see if it is OK
893 old_flags = (jushort) k_old_method->access_flags().get_flags();
894 if ((old_flags & JVM_ACC_PRIVATE) == 0
895 // hack: private should be treated as final, but alas
896 || (old_flags & (JVM_ACC_FINAL|JVM_ACC_STATIC)) == 0
897 ) {
898 // deleted methods must be private
899 return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_METHOD_DELETED;
900 }
901 RC_TRACE(0x00008000, ("Method deleted: old: %s [%d]",
902 k_old_method->name_and_sig_as_C_string(), oi));
903 ++oi; // advance to next old method
904 break;
905 default:
906 ShouldNotReachHere();
907 }
908 }
909
910 return JVMTI_ERROR_NONE;
911 }
912
913
914 // Find new constant pool index value for old constant pool index value
915 // by seaching the index map. Returns zero (0) if there is no mapped
916 // value for the old constant pool index.
find_new_index(int old_index)917 int VM_RedefineClasses::find_new_index(int old_index) {
918 if (_index_map_count == 0) {
919 // map is empty so nothing can be found
920 return 0;
921 }
922
923 if (old_index < 1 || old_index >= _index_map_p->length()) {
924 // The old_index is out of range so it is not mapped. This should
925 // not happen in regular constant pool merging use, but it can
926 // happen if a corrupt annotation is processed.
927 return 0;
928 }
929
930 int value = _index_map_p->at(old_index);
931 if (value == -1) {
932 // the old_index is not mapped
933 return 0;
934 }
935
936 return value;
937 } // end find_new_index()
938
939
940 // Find new bootstrap specifier index value for old bootstrap specifier index
941 // value by seaching the index map. Returns unused index (-1) if there is
942 // no mapped value for the old bootstrap specifier index.
find_new_operand_index(int old_index)943 int VM_RedefineClasses::find_new_operand_index(int old_index) {
944 if (_operands_index_map_count == 0) {
945 // map is empty so nothing can be found
946 return -1;
947 }
948
949 if (old_index == -1 || old_index >= _operands_index_map_p->length()) {
950 // The old_index is out of range so it is not mapped.
951 // This should not happen in regular constant pool merging use.
952 return -1;
953 }
954
955 int value = _operands_index_map_p->at(old_index);
956 if (value == -1) {
957 // the old_index is not mapped
958 return -1;
959 }
960
961 return value;
962 } // end find_new_operand_index()
963
964
965 // Returns true if the current mismatch is due to a resolved/unresolved
966 // class pair. Otherwise, returns false.
is_unresolved_class_mismatch(constantPoolHandle cp1,int index1,constantPoolHandle cp2,int index2)967 bool VM_RedefineClasses::is_unresolved_class_mismatch(constantPoolHandle cp1,
968 int index1, constantPoolHandle cp2, int index2) {
969
970 jbyte t1 = cp1->tag_at(index1).value();
971 if (t1 != JVM_CONSTANT_Class && t1 != JVM_CONSTANT_UnresolvedClass) {
972 return false; // wrong entry type; not our special case
973 }
974
975 jbyte t2 = cp2->tag_at(index2).value();
976 if (t2 != JVM_CONSTANT_Class && t2 != JVM_CONSTANT_UnresolvedClass) {
977 return false; // wrong entry type; not our special case
978 }
979
980 if (t1 == t2) {
981 return false; // not a mismatch; not our special case
982 }
983
984 char *s1 = cp1->klass_name_at(index1)->as_C_string();
985 char *s2 = cp2->klass_name_at(index2)->as_C_string();
986 if (strcmp(s1, s2) != 0) {
987 return false; // strings don't match; not our special case
988 }
989
990 return true; // made it through the gauntlet; this is our special case
991 } // end is_unresolved_class_mismatch()
992
993
load_new_class_versions(TRAPS)994 jvmtiError VM_RedefineClasses::load_new_class_versions(TRAPS) {
995
996 // For consistency allocate memory using os::malloc wrapper.
997 _scratch_classes = (Klass**)
998 os::malloc(sizeof(Klass*) * _class_count, mtClass);
999 if (_scratch_classes == NULL) {
1000 return JVMTI_ERROR_OUT_OF_MEMORY;
1001 }
1002 // Zero initialize the _scratch_classes array.
1003 for (int i = 0; i < _class_count; i++) {
1004 _scratch_classes[i] = NULL;
1005 }
1006
1007 ResourceMark rm(THREAD);
1008
1009 JvmtiThreadState *state = JvmtiThreadState::state_for(JavaThread::current());
1010 // state can only be NULL if the current thread is exiting which
1011 // should not happen since we're trying to do a RedefineClasses
1012 guarantee(state != NULL, "exiting thread calling load_new_class_versions");
1013 for (int i = 0; i < _class_count; i++) {
1014 // Create HandleMark so that any handles created while loading new class
1015 // versions are deleted. Constant pools are deallocated while merging
1016 // constant pools
1017 HandleMark hm(THREAD);
1018 instanceKlassHandle the_class(THREAD, get_ik(_class_defs[i].klass));
1019 Symbol* the_class_sym = the_class->name();
1020
1021 // RC_TRACE_WITH_THREAD macro has an embedded ResourceMark
1022 RC_TRACE_WITH_THREAD(0x00000001, THREAD,
1023 ("loading name=%s kind=%d (avail_mem=" UINT64_FORMAT "K)",
1024 the_class->external_name(), _class_load_kind,
1025 os::available_memory() >> 10));
1026
1027 ClassFileStream st((u1*) _class_defs[i].class_bytes,
1028 _class_defs[i].class_byte_count, (char *)"__VM_RedefineClasses__");
1029
1030 // Parse the stream.
1031 Handle the_class_loader(THREAD, the_class->class_loader());
1032 Handle protection_domain(THREAD, the_class->protection_domain());
1033 // Set redefined class handle in JvmtiThreadState class.
1034 // This redefined class is sent to agent event handler for class file
1035 // load hook event.
1036 state->set_class_being_redefined(&the_class, _class_load_kind);
1037
1038 Klass* k = SystemDictionary::parse_stream(the_class_sym,
1039 the_class_loader,
1040 protection_domain,
1041 &st,
1042 THREAD);
1043 // Clear class_being_redefined just to be sure.
1044 state->clear_class_being_redefined();
1045
1046 // TODO: if this is retransform, and nothing changed we can skip it
1047
1048 instanceKlassHandle scratch_class (THREAD, k);
1049
1050 // Need to clean up allocated InstanceKlass if there's an error so assign
1051 // the result here. Caller deallocates all the scratch classes in case of
1052 // an error.
1053 _scratch_classes[i] = k;
1054
1055 if (HAS_PENDING_EXCEPTION) {
1056 Symbol* ex_name = PENDING_EXCEPTION->klass()->name();
1057 // RC_TRACE_WITH_THREAD macro has an embedded ResourceMark
1058 RC_TRACE_WITH_THREAD(0x00000002, THREAD, ("parse_stream exception: '%s'",
1059 ex_name->as_C_string()));
1060 CLEAR_PENDING_EXCEPTION;
1061
1062 if (ex_name == vmSymbols::java_lang_UnsupportedClassVersionError()) {
1063 return JVMTI_ERROR_UNSUPPORTED_VERSION;
1064 } else if (ex_name == vmSymbols::java_lang_ClassFormatError()) {
1065 return JVMTI_ERROR_INVALID_CLASS_FORMAT;
1066 } else if (ex_name == vmSymbols::java_lang_ClassCircularityError()) {
1067 return JVMTI_ERROR_CIRCULAR_CLASS_DEFINITION;
1068 } else if (ex_name == vmSymbols::java_lang_NoClassDefFoundError()) {
1069 // The message will be "XXX (wrong name: YYY)"
1070 return JVMTI_ERROR_NAMES_DONT_MATCH;
1071 } else if (ex_name == vmSymbols::java_lang_OutOfMemoryError()) {
1072 return JVMTI_ERROR_OUT_OF_MEMORY;
1073 } else { // Just in case more exceptions can be thrown..
1074 return JVMTI_ERROR_FAILS_VERIFICATION;
1075 }
1076 }
1077
1078 // Ensure class is linked before redefine
1079 if (!the_class->is_linked()) {
1080 the_class->link_class(THREAD);
1081 if (HAS_PENDING_EXCEPTION) {
1082 Symbol* ex_name = PENDING_EXCEPTION->klass()->name();
1083 // RC_TRACE_WITH_THREAD macro has an embedded ResourceMark
1084 RC_TRACE_WITH_THREAD(0x00000002, THREAD, ("link_class exception: '%s'",
1085 ex_name->as_C_string()));
1086 CLEAR_PENDING_EXCEPTION;
1087 if (ex_name == vmSymbols::java_lang_OutOfMemoryError()) {
1088 return JVMTI_ERROR_OUT_OF_MEMORY;
1089 } else {
1090 return JVMTI_ERROR_INTERNAL;
1091 }
1092 }
1093 }
1094
1095 // Do the validity checks in compare_and_normalize_class_versions()
1096 // before verifying the byte codes. By doing these checks first, we
1097 // limit the number of functions that require redirection from
1098 // the_class to scratch_class. In particular, we don't have to
1099 // modify JNI GetSuperclass() and thus won't change its performance.
1100 jvmtiError res = compare_and_normalize_class_versions(the_class,
1101 scratch_class);
1102 if (res != JVMTI_ERROR_NONE) {
1103 return res;
1104 }
1105
1106 // verify what the caller passed us
1107 {
1108 // The bug 6214132 caused the verification to fail.
1109 // Information about the_class and scratch_class is temporarily
1110 // recorded into jvmtiThreadState. This data is used to redirect
1111 // the_class to scratch_class in the JVM_* functions called by the
1112 // verifier. Please, refer to jvmtiThreadState.hpp for the detailed
1113 // description.
1114 RedefineVerifyMark rvm(&the_class, &scratch_class, state);
1115 Verifier::verify(
1116 scratch_class, Verifier::ThrowException, true, THREAD);
1117 }
1118
1119 if (HAS_PENDING_EXCEPTION) {
1120 Symbol* ex_name = PENDING_EXCEPTION->klass()->name();
1121 // RC_TRACE_WITH_THREAD macro has an embedded ResourceMark
1122 RC_TRACE_WITH_THREAD(0x00000002, THREAD,
1123 ("verify_byte_codes exception: '%s'", ex_name->as_C_string()));
1124 CLEAR_PENDING_EXCEPTION;
1125 if (ex_name == vmSymbols::java_lang_OutOfMemoryError()) {
1126 return JVMTI_ERROR_OUT_OF_MEMORY;
1127 } else {
1128 // tell the caller the bytecodes are bad
1129 return JVMTI_ERROR_FAILS_VERIFICATION;
1130 }
1131 }
1132
1133 res = merge_cp_and_rewrite(the_class, scratch_class, THREAD);
1134 if (HAS_PENDING_EXCEPTION) {
1135 Symbol* ex_name = PENDING_EXCEPTION->klass()->name();
1136 // RC_TRACE_WITH_THREAD macro has an embedded ResourceMark
1137 RC_TRACE_WITH_THREAD(0x00000002, THREAD,
1138 ("merge_cp_and_rewrite exception: '%s'", ex_name->as_C_string()));
1139 CLEAR_PENDING_EXCEPTION;
1140 if (ex_name == vmSymbols::java_lang_OutOfMemoryError()) {
1141 return JVMTI_ERROR_OUT_OF_MEMORY;
1142 } else {
1143 return JVMTI_ERROR_INTERNAL;
1144 }
1145 }
1146
1147 if (VerifyMergedCPBytecodes) {
1148 // verify what we have done during constant pool merging
1149 {
1150 RedefineVerifyMark rvm(&the_class, &scratch_class, state);
1151 Verifier::verify(scratch_class, Verifier::ThrowException, true, THREAD);
1152 }
1153
1154 if (HAS_PENDING_EXCEPTION) {
1155 Symbol* ex_name = PENDING_EXCEPTION->klass()->name();
1156 // RC_TRACE_WITH_THREAD macro has an embedded ResourceMark
1157 RC_TRACE_WITH_THREAD(0x00000002, THREAD,
1158 ("verify_byte_codes post merge-CP exception: '%s'",
1159 ex_name->as_C_string()));
1160 CLEAR_PENDING_EXCEPTION;
1161 if (ex_name == vmSymbols::java_lang_OutOfMemoryError()) {
1162 return JVMTI_ERROR_OUT_OF_MEMORY;
1163 } else {
1164 // tell the caller that constant pool merging screwed up
1165 return JVMTI_ERROR_INTERNAL;
1166 }
1167 }
1168 }
1169
1170 Rewriter::rewrite(scratch_class, THREAD);
1171 if (!HAS_PENDING_EXCEPTION) {
1172 scratch_class->link_methods(THREAD);
1173 }
1174 if (HAS_PENDING_EXCEPTION) {
1175 Symbol* ex_name = PENDING_EXCEPTION->klass()->name();
1176 // RC_TRACE_WITH_THREAD macro has an embedded ResourceMark
1177 RC_TRACE_WITH_THREAD(0x00000002, THREAD,
1178 ("Rewriter::rewrite or link_methods exception: '%s'", ex_name->as_C_string()));
1179 CLEAR_PENDING_EXCEPTION;
1180 if (ex_name == vmSymbols::java_lang_OutOfMemoryError()) {
1181 return JVMTI_ERROR_OUT_OF_MEMORY;
1182 } else {
1183 return JVMTI_ERROR_INTERNAL;
1184 }
1185 }
1186
1187 // RC_TRACE_WITH_THREAD macro has an embedded ResourceMark
1188 RC_TRACE_WITH_THREAD(0x00000001, THREAD,
1189 ("loaded name=%s (avail_mem=" UINT64_FORMAT "K)",
1190 the_class->external_name(), os::available_memory() >> 10));
1191 }
1192
1193 return JVMTI_ERROR_NONE;
1194 }
1195
1196
1197 // Map old_index to new_index as needed. scratch_cp is only needed
1198 // for RC_TRACE() calls.
map_index(constantPoolHandle scratch_cp,int old_index,int new_index)1199 void VM_RedefineClasses::map_index(constantPoolHandle scratch_cp,
1200 int old_index, int new_index) {
1201 if (find_new_index(old_index) != 0) {
1202 // old_index is already mapped
1203 return;
1204 }
1205
1206 if (old_index == new_index) {
1207 // no mapping is needed
1208 return;
1209 }
1210
1211 _index_map_p->at_put(old_index, new_index);
1212 _index_map_count++;
1213
1214 RC_TRACE(0x00040000, ("mapped tag %d at index %d to %d",
1215 scratch_cp->tag_at(old_index).value(), old_index, new_index));
1216 } // end map_index()
1217
1218
1219 // Map old_index to new_index as needed.
map_operand_index(int old_index,int new_index)1220 void VM_RedefineClasses::map_operand_index(int old_index, int new_index) {
1221 if (find_new_operand_index(old_index) != -1) {
1222 // old_index is already mapped
1223 return;
1224 }
1225
1226 if (old_index == new_index) {
1227 // no mapping is needed
1228 return;
1229 }
1230
1231 _operands_index_map_p->at_put(old_index, new_index);
1232 _operands_index_map_count++;
1233
1234 RC_TRACE(0x00040000, ("mapped bootstrap specifier at index %d to %d", old_index, new_index));
1235 } // end map_index()
1236
1237
1238 // Merge old_cp and scratch_cp and return the results of the merge via
1239 // merge_cp_p. The number of entries in *merge_cp_p is returned via
1240 // merge_cp_length_p. The entries in old_cp occupy the same locations
1241 // in *merge_cp_p. Also creates a map of indices from entries in
1242 // scratch_cp to the corresponding entry in *merge_cp_p. Index map
1243 // entries are only created for entries in scratch_cp that occupy a
1244 // different location in *merged_cp_p.
merge_constant_pools(constantPoolHandle old_cp,constantPoolHandle scratch_cp,constantPoolHandle * merge_cp_p,int * merge_cp_length_p,TRAPS)1245 bool VM_RedefineClasses::merge_constant_pools(constantPoolHandle old_cp,
1246 constantPoolHandle scratch_cp, constantPoolHandle *merge_cp_p,
1247 int *merge_cp_length_p, TRAPS) {
1248
1249 if (merge_cp_p == NULL) {
1250 assert(false, "caller must provide scratch constantPool");
1251 return false; // robustness
1252 }
1253 if (merge_cp_length_p == NULL) {
1254 assert(false, "caller must provide scratch CP length");
1255 return false; // robustness
1256 }
1257 // Worst case we need old_cp->length() + scratch_cp()->length(),
1258 // but the caller might be smart so make sure we have at least
1259 // the minimum.
1260 if ((*merge_cp_p)->length() < old_cp->length()) {
1261 assert(false, "merge area too small");
1262 return false; // robustness
1263 }
1264
1265 RC_TRACE_WITH_THREAD(0x00010000, THREAD,
1266 ("old_cp_len=%d, scratch_cp_len=%d", old_cp->length(),
1267 scratch_cp->length()));
1268
1269 {
1270 // Pass 0:
1271 // The old_cp is copied to *merge_cp_p; this means that any code
1272 // using old_cp does not have to change. This work looks like a
1273 // perfect fit for ConstantPool*::copy_cp_to(), but we need to
1274 // handle one special case:
1275 // - revert JVM_CONSTANT_Class to JVM_CONSTANT_UnresolvedClass
1276 // This will make verification happy.
1277
1278 int old_i; // index into old_cp
1279
1280 // index zero (0) is not used in constantPools
1281 for (old_i = 1; old_i < old_cp->length(); old_i++) {
1282 // leave debugging crumb
1283 jbyte old_tag = old_cp->tag_at(old_i).value();
1284 switch (old_tag) {
1285 case JVM_CONSTANT_Class:
1286 case JVM_CONSTANT_UnresolvedClass:
1287 // revert the copy to JVM_CONSTANT_UnresolvedClass
1288 // May be resolving while calling this so do the same for
1289 // JVM_CONSTANT_UnresolvedClass (klass_name_at() deals with transition)
1290 (*merge_cp_p)->unresolved_klass_at_put(old_i,
1291 old_cp->klass_name_at(old_i));
1292 break;
1293
1294 case JVM_CONSTANT_Double:
1295 case JVM_CONSTANT_Long:
1296 // just copy the entry to *merge_cp_p, but double and long take
1297 // two constant pool entries
1298 ConstantPool::copy_entry_to(old_cp, old_i, *merge_cp_p, old_i, CHECK_0);
1299 old_i++;
1300 break;
1301
1302 default:
1303 // just copy the entry to *merge_cp_p
1304 ConstantPool::copy_entry_to(old_cp, old_i, *merge_cp_p, old_i, CHECK_0);
1305 break;
1306 }
1307 } // end for each old_cp entry
1308
1309 ConstantPool::copy_operands(old_cp, *merge_cp_p, CHECK_0);
1310 (*merge_cp_p)->extend_operands(scratch_cp, CHECK_0);
1311
1312 // We don't need to sanity check that *merge_cp_length_p is within
1313 // *merge_cp_p bounds since we have the minimum on-entry check above.
1314 (*merge_cp_length_p) = old_i;
1315 }
1316
1317 // merge_cp_len should be the same as old_cp->length() at this point
1318 // so this trace message is really a "warm-and-breathing" message.
1319 RC_TRACE_WITH_THREAD(0x00020000, THREAD,
1320 ("after pass 0: merge_cp_len=%d", *merge_cp_length_p));
1321
1322 int scratch_i; // index into scratch_cp
1323 {
1324 // Pass 1a:
1325 // Compare scratch_cp entries to the old_cp entries that we have
1326 // already copied to *merge_cp_p. In this pass, we are eliminating
1327 // exact duplicates (matching entry at same index) so we only
1328 // compare entries in the common indice range.
1329 int increment = 1;
1330 int pass1a_length = MIN2(old_cp->length(), scratch_cp->length());
1331 for (scratch_i = 1; scratch_i < pass1a_length; scratch_i += increment) {
1332 switch (scratch_cp->tag_at(scratch_i).value()) {
1333 case JVM_CONSTANT_Double:
1334 case JVM_CONSTANT_Long:
1335 // double and long take two constant pool entries
1336 increment = 2;
1337 break;
1338
1339 default:
1340 increment = 1;
1341 break;
1342 }
1343
1344 bool match = scratch_cp->compare_entry_to(scratch_i, *merge_cp_p,
1345 scratch_i, CHECK_0);
1346 if (match) {
1347 // found a match at the same index so nothing more to do
1348 continue;
1349 } else if (is_unresolved_class_mismatch(scratch_cp, scratch_i,
1350 *merge_cp_p, scratch_i)) {
1351 // The mismatch in compare_entry_to() above is because of a
1352 // resolved versus unresolved class entry at the same index
1353 // with the same string value. Since Pass 0 reverted any
1354 // class entries to unresolved class entries in *merge_cp_p,
1355 // we go with the unresolved class entry.
1356 continue;
1357 }
1358
1359 int found_i = scratch_cp->find_matching_entry(scratch_i, *merge_cp_p,
1360 CHECK_0);
1361 if (found_i != 0) {
1362 guarantee(found_i != scratch_i,
1363 "compare_entry_to() and find_matching_entry() do not agree");
1364
1365 // Found a matching entry somewhere else in *merge_cp_p so
1366 // just need a mapping entry.
1367 map_index(scratch_cp, scratch_i, found_i);
1368 continue;
1369 }
1370
1371 // The find_matching_entry() call above could fail to find a match
1372 // due to a resolved versus unresolved class or string entry situation
1373 // like we solved above with the is_unresolved_*_mismatch() calls.
1374 // However, we would have to call is_unresolved_*_mismatch() over
1375 // all of *merge_cp_p (potentially) and that doesn't seem to be
1376 // worth the time.
1377
1378 // No match found so we have to append this entry and any unique
1379 // referenced entries to *merge_cp_p.
1380 append_entry(scratch_cp, scratch_i, merge_cp_p, merge_cp_length_p,
1381 CHECK_0);
1382 }
1383 }
1384
1385 RC_TRACE_WITH_THREAD(0x00020000, THREAD,
1386 ("after pass 1a: merge_cp_len=%d, scratch_i=%d, index_map_len=%d",
1387 *merge_cp_length_p, scratch_i, _index_map_count));
1388
1389 if (scratch_i < scratch_cp->length()) {
1390 // Pass 1b:
1391 // old_cp is smaller than scratch_cp so there are entries in
1392 // scratch_cp that we have not yet processed. We take care of
1393 // those now.
1394 int increment = 1;
1395 for (; scratch_i < scratch_cp->length(); scratch_i += increment) {
1396 switch (scratch_cp->tag_at(scratch_i).value()) {
1397 case JVM_CONSTANT_Double:
1398 case JVM_CONSTANT_Long:
1399 // double and long take two constant pool entries
1400 increment = 2;
1401 break;
1402
1403 default:
1404 increment = 1;
1405 break;
1406 }
1407
1408 int found_i =
1409 scratch_cp->find_matching_entry(scratch_i, *merge_cp_p, CHECK_0);
1410 if (found_i != 0) {
1411 // Found a matching entry somewhere else in *merge_cp_p so
1412 // just need a mapping entry.
1413 map_index(scratch_cp, scratch_i, found_i);
1414 continue;
1415 }
1416
1417 // No match found so we have to append this entry and any unique
1418 // referenced entries to *merge_cp_p.
1419 append_entry(scratch_cp, scratch_i, merge_cp_p, merge_cp_length_p,
1420 CHECK_0);
1421 }
1422
1423 RC_TRACE_WITH_THREAD(0x00020000, THREAD,
1424 ("after pass 1b: merge_cp_len=%d, scratch_i=%d, index_map_len=%d",
1425 *merge_cp_length_p, scratch_i, _index_map_count));
1426 }
1427 finalize_operands_merge(*merge_cp_p, THREAD);
1428
1429 return true;
1430 } // end merge_constant_pools()
1431
1432
1433 // Scoped object to clean up the constant pool(s) created for merging
1434 class MergeCPCleaner {
1435 ClassLoaderData* _loader_data;
1436 ConstantPool* _cp;
1437 ConstantPool* _scratch_cp;
1438 public:
MergeCPCleaner(ClassLoaderData * loader_data,ConstantPool * merge_cp)1439 MergeCPCleaner(ClassLoaderData* loader_data, ConstantPool* merge_cp) :
1440 _loader_data(loader_data), _cp(merge_cp), _scratch_cp(NULL) {}
~MergeCPCleaner()1441 ~MergeCPCleaner() {
1442 _loader_data->add_to_deallocate_list(_cp);
1443 if (_scratch_cp != NULL) {
1444 _loader_data->add_to_deallocate_list(_scratch_cp);
1445 }
1446 }
add_scratch_cp(ConstantPool * scratch_cp)1447 void add_scratch_cp(ConstantPool* scratch_cp) { _scratch_cp = scratch_cp; }
1448 };
1449
1450 // Merge constant pools between the_class and scratch_class and
1451 // potentially rewrite bytecodes in scratch_class to use the merged
1452 // constant pool.
merge_cp_and_rewrite(instanceKlassHandle the_class,instanceKlassHandle scratch_class,TRAPS)1453 jvmtiError VM_RedefineClasses::merge_cp_and_rewrite(
1454 instanceKlassHandle the_class, instanceKlassHandle scratch_class,
1455 TRAPS) {
1456 // worst case merged constant pool length is old and new combined
1457 int merge_cp_length = the_class->constants()->length()
1458 + scratch_class->constants()->length();
1459
1460 // Constant pools are not easily reused so we allocate a new one
1461 // each time.
1462 // merge_cp is created unsafe for concurrent GC processing. It
1463 // should be marked safe before discarding it. Even though
1464 // garbage, if it crosses a card boundary, it may be scanned
1465 // in order to find the start of the first complete object on the card.
1466 ClassLoaderData* loader_data = the_class->class_loader_data();
1467 ConstantPool* merge_cp_oop =
1468 ConstantPool::allocate(loader_data,
1469 merge_cp_length,
1470 CHECK_(JVMTI_ERROR_OUT_OF_MEMORY));
1471 MergeCPCleaner cp_cleaner(loader_data, merge_cp_oop);
1472
1473 HandleMark hm(THREAD); // make sure handles are cleared before
1474 // MergeCPCleaner clears out merge_cp_oop
1475 constantPoolHandle merge_cp(THREAD, merge_cp_oop);
1476
1477 // Get constants() from the old class because it could have been rewritten
1478 // while we were at a safepoint allocating a new constant pool.
1479 constantPoolHandle old_cp(THREAD, the_class->constants());
1480 constantPoolHandle scratch_cp(THREAD, scratch_class->constants());
1481
1482 // If the length changed, the class was redefined out from under us. Return
1483 // an error.
1484 if (merge_cp_length != the_class->constants()->length()
1485 + scratch_class->constants()->length()) {
1486 return JVMTI_ERROR_INTERNAL;
1487 }
1488
1489 // Update the version number of the constant pool
1490 merge_cp->increment_and_save_version(old_cp->version());
1491
1492 ResourceMark rm(THREAD);
1493 _index_map_count = 0;
1494 _index_map_p = new intArray(scratch_cp->length(), -1);
1495
1496 _operands_cur_length = ConstantPool::operand_array_length(old_cp->operands());
1497 _operands_index_map_count = 0;
1498 _operands_index_map_p = new intArray(
1499 ConstantPool::operand_array_length(scratch_cp->operands()), -1);
1500
1501 // reference to the cp holder is needed for copy_operands()
1502 merge_cp->set_pool_holder(scratch_class());
1503 bool result = merge_constant_pools(old_cp, scratch_cp, &merge_cp,
1504 &merge_cp_length, THREAD);
1505 merge_cp->set_pool_holder(NULL);
1506
1507 if (!result) {
1508 // The merge can fail due to memory allocation failure or due
1509 // to robustness checks.
1510 return JVMTI_ERROR_INTERNAL;
1511 }
1512
1513 RC_TRACE_WITH_THREAD(0x00010000, THREAD,
1514 ("merge_cp_len=%d, index_map_len=%d", merge_cp_length, _index_map_count));
1515
1516 if (_index_map_count == 0) {
1517 // there is nothing to map between the new and merged constant pools
1518
1519 if (old_cp->length() == scratch_cp->length()) {
1520 // The old and new constant pools are the same length and the
1521 // index map is empty. This means that the three constant pools
1522 // are equivalent (but not the same). Unfortunately, the new
1523 // constant pool has not gone through link resolution nor have
1524 // the new class bytecodes gone through constant pool cache
1525 // rewriting so we can't use the old constant pool with the new
1526 // class.
1527
1528 // toss the merged constant pool at return
1529 } else if (old_cp->length() < scratch_cp->length()) {
1530 // The old constant pool has fewer entries than the new constant
1531 // pool and the index map is empty. This means the new constant
1532 // pool is a superset of the old constant pool. However, the old
1533 // class bytecodes have already gone through constant pool cache
1534 // rewriting so we can't use the new constant pool with the old
1535 // class.
1536
1537 // toss the merged constant pool at return
1538 } else {
1539 // The old constant pool has more entries than the new constant
1540 // pool and the index map is empty. This means that both the old
1541 // and merged constant pools are supersets of the new constant
1542 // pool.
1543
1544 // Replace the new constant pool with a shrunken copy of the
1545 // merged constant pool
1546 set_new_constant_pool(loader_data, scratch_class, merge_cp, merge_cp_length,
1547 CHECK_(JVMTI_ERROR_OUT_OF_MEMORY));
1548 // The new constant pool replaces scratch_cp so have cleaner clean it up.
1549 // It can't be cleaned up while there are handles to it.
1550 cp_cleaner.add_scratch_cp(scratch_cp());
1551 }
1552 } else {
1553 if (RC_TRACE_ENABLED(0x00040000)) {
1554 // don't want to loop unless we are tracing
1555 int count = 0;
1556 for (int i = 1; i < _index_map_p->length(); i++) {
1557 int value = _index_map_p->at(i);
1558
1559 if (value != -1) {
1560 RC_TRACE_WITH_THREAD(0x00040000, THREAD,
1561 ("index_map[%d]: old=%d new=%d", count, i, value));
1562 count++;
1563 }
1564 }
1565 }
1566
1567 // We have entries mapped between the new and merged constant pools
1568 // so we have to rewrite some constant pool references.
1569 if (!rewrite_cp_refs(scratch_class, THREAD)) {
1570 return JVMTI_ERROR_INTERNAL;
1571 }
1572
1573 // Replace the new constant pool with a shrunken copy of the
1574 // merged constant pool so now the rewritten bytecodes have
1575 // valid references; the previous new constant pool will get
1576 // GCed.
1577 set_new_constant_pool(loader_data, scratch_class, merge_cp, merge_cp_length,
1578 CHECK_(JVMTI_ERROR_OUT_OF_MEMORY));
1579 // The new constant pool replaces scratch_cp so have cleaner clean it up.
1580 // It can't be cleaned up while there are handles to it.
1581 cp_cleaner.add_scratch_cp(scratch_cp());
1582 }
1583
1584 return JVMTI_ERROR_NONE;
1585 } // end merge_cp_and_rewrite()
1586
1587
1588 // Rewrite constant pool references in klass scratch_class.
rewrite_cp_refs(instanceKlassHandle scratch_class,TRAPS)1589 bool VM_RedefineClasses::rewrite_cp_refs(instanceKlassHandle scratch_class,
1590 TRAPS) {
1591
1592 // rewrite constant pool references in the methods:
1593 if (!rewrite_cp_refs_in_methods(scratch_class, THREAD)) {
1594 // propagate failure back to caller
1595 return false;
1596 }
1597
1598 // rewrite constant pool references in the class_annotations:
1599 if (!rewrite_cp_refs_in_class_annotations(scratch_class, THREAD)) {
1600 // propagate failure back to caller
1601 return false;
1602 }
1603
1604 // rewrite constant pool references in the fields_annotations:
1605 if (!rewrite_cp_refs_in_fields_annotations(scratch_class, THREAD)) {
1606 // propagate failure back to caller
1607 return false;
1608 }
1609
1610 // rewrite constant pool references in the methods_annotations:
1611 if (!rewrite_cp_refs_in_methods_annotations(scratch_class, THREAD)) {
1612 // propagate failure back to caller
1613 return false;
1614 }
1615
1616 // rewrite constant pool references in the methods_parameter_annotations:
1617 if (!rewrite_cp_refs_in_methods_parameter_annotations(scratch_class,
1618 THREAD)) {
1619 // propagate failure back to caller
1620 return false;
1621 }
1622
1623 // rewrite constant pool references in the methods_default_annotations:
1624 if (!rewrite_cp_refs_in_methods_default_annotations(scratch_class,
1625 THREAD)) {
1626 // propagate failure back to caller
1627 return false;
1628 }
1629
1630 // rewrite constant pool references in the class_type_annotations:
1631 if (!rewrite_cp_refs_in_class_type_annotations(scratch_class, THREAD)) {
1632 // propagate failure back to caller
1633 return false;
1634 }
1635
1636 // rewrite constant pool references in the fields_type_annotations:
1637 if (!rewrite_cp_refs_in_fields_type_annotations(scratch_class, THREAD)) {
1638 // propagate failure back to caller
1639 return false;
1640 }
1641
1642 // rewrite constant pool references in the methods_type_annotations:
1643 if (!rewrite_cp_refs_in_methods_type_annotations(scratch_class, THREAD)) {
1644 // propagate failure back to caller
1645 return false;
1646 }
1647
1648 // There can be type annotations in the Code part of a method_info attribute.
1649 // These annotations are not accessible, even by reflection.
1650 // Currently they are not even parsed by the ClassFileParser.
1651 // If runtime access is added they will also need to be rewritten.
1652
1653 // rewrite source file name index:
1654 u2 source_file_name_idx = scratch_class->source_file_name_index();
1655 if (source_file_name_idx != 0) {
1656 u2 new_source_file_name_idx = find_new_index(source_file_name_idx);
1657 if (new_source_file_name_idx != 0) {
1658 scratch_class->set_source_file_name_index(new_source_file_name_idx);
1659 }
1660 }
1661
1662 // rewrite class generic signature index:
1663 u2 generic_signature_index = scratch_class->generic_signature_index();
1664 if (generic_signature_index != 0) {
1665 u2 new_generic_signature_index = find_new_index(generic_signature_index);
1666 if (new_generic_signature_index != 0) {
1667 scratch_class->set_generic_signature_index(new_generic_signature_index);
1668 }
1669 }
1670
1671 return true;
1672 } // end rewrite_cp_refs()
1673
1674 // Rewrite constant pool references in the methods.
rewrite_cp_refs_in_methods(instanceKlassHandle scratch_class,TRAPS)1675 bool VM_RedefineClasses::rewrite_cp_refs_in_methods(
1676 instanceKlassHandle scratch_class, TRAPS) {
1677
1678 Array<Method*>* methods = scratch_class->methods();
1679
1680 if (methods == NULL || methods->length() == 0) {
1681 // no methods so nothing to do
1682 return true;
1683 }
1684
1685 // rewrite constant pool references in the methods:
1686 for (int i = methods->length() - 1; i >= 0; i--) {
1687 methodHandle method(THREAD, methods->at(i));
1688 methodHandle new_method;
1689 rewrite_cp_refs_in_method(method, &new_method, THREAD);
1690 if (!new_method.is_null()) {
1691 // the method has been replaced so save the new method version
1692 // even in the case of an exception. original method is on the
1693 // deallocation list.
1694 methods->at_put(i, new_method());
1695 }
1696 if (HAS_PENDING_EXCEPTION) {
1697 Symbol* ex_name = PENDING_EXCEPTION->klass()->name();
1698 // RC_TRACE_WITH_THREAD macro has an embedded ResourceMark
1699 RC_TRACE_WITH_THREAD(0x00000002, THREAD,
1700 ("rewrite_cp_refs_in_method exception: '%s'", ex_name->as_C_string()));
1701 // Need to clear pending exception here as the super caller sets
1702 // the JVMTI_ERROR_INTERNAL if the returned value is false.
1703 CLEAR_PENDING_EXCEPTION;
1704 return false;
1705 }
1706 }
1707
1708 return true;
1709 }
1710
1711
1712 // Rewrite constant pool references in the specific method. This code
1713 // was adapted from Rewriter::rewrite_method().
rewrite_cp_refs_in_method(methodHandle method,methodHandle * new_method_p,TRAPS)1714 void VM_RedefineClasses::rewrite_cp_refs_in_method(methodHandle method,
1715 methodHandle *new_method_p, TRAPS) {
1716
1717 *new_method_p = methodHandle(); // default is no new method
1718
1719 // We cache a pointer to the bytecodes here in code_base. If GC
1720 // moves the Method*, then the bytecodes will also move which
1721 // will likely cause a crash. We create a No_Safepoint_Verifier
1722 // object to detect whether we pass a possible safepoint in this
1723 // code block.
1724 No_Safepoint_Verifier nsv;
1725
1726 // Bytecodes and their length
1727 address code_base = method->code_base();
1728 int code_length = method->code_size();
1729
1730 int bc_length;
1731 for (int bci = 0; bci < code_length; bci += bc_length) {
1732 address bcp = code_base + bci;
1733 Bytecodes::Code c = (Bytecodes::Code)(*bcp);
1734
1735 bc_length = Bytecodes::length_for(c);
1736 if (bc_length == 0) {
1737 // More complicated bytecodes report a length of zero so
1738 // we have to try again a slightly different way.
1739 bc_length = Bytecodes::length_at(method(), bcp);
1740 }
1741
1742 assert(bc_length != 0, "impossible bytecode length");
1743
1744 switch (c) {
1745 case Bytecodes::_ldc:
1746 {
1747 int cp_index = *(bcp + 1);
1748 int new_index = find_new_index(cp_index);
1749
1750 if (StressLdcRewrite && new_index == 0) {
1751 // If we are stressing ldc -> ldc_w rewriting, then we
1752 // always need a new_index value.
1753 new_index = cp_index;
1754 }
1755 if (new_index != 0) {
1756 // the original index is mapped so we have more work to do
1757 if (!StressLdcRewrite && new_index <= max_jubyte) {
1758 // The new value can still use ldc instead of ldc_w
1759 // unless we are trying to stress ldc -> ldc_w rewriting
1760 RC_TRACE_WITH_THREAD(0x00080000, THREAD,
1761 ("%s@" INTPTR_FORMAT " old=%d, new=%d", Bytecodes::name(c),
1762 bcp, cp_index, new_index));
1763 *(bcp + 1) = new_index;
1764 } else {
1765 RC_TRACE_WITH_THREAD(0x00080000, THREAD,
1766 ("%s->ldc_w@" INTPTR_FORMAT " old=%d, new=%d",
1767 Bytecodes::name(c), bcp, cp_index, new_index));
1768 // the new value needs ldc_w instead of ldc
1769 u_char inst_buffer[4]; // max instruction size is 4 bytes
1770 bcp = (address)inst_buffer;
1771 // construct new instruction sequence
1772 *bcp = Bytecodes::_ldc_w;
1773 bcp++;
1774 // Rewriter::rewrite_method() does not rewrite ldc -> ldc_w.
1775 // See comment below for difference between put_Java_u2()
1776 // and put_native_u2().
1777 Bytes::put_Java_u2(bcp, new_index);
1778
1779 Relocator rc(method, NULL /* no RelocatorListener needed */);
1780 methodHandle m;
1781 {
1782 Pause_No_Safepoint_Verifier pnsv(&nsv);
1783
1784 // ldc is 2 bytes and ldc_w is 3 bytes
1785 m = rc.insert_space_at(bci, 3, inst_buffer, CHECK);
1786 }
1787
1788 // return the new method so that the caller can update
1789 // the containing class
1790 *new_method_p = method = m;
1791 // switch our bytecode processing loop from the old method
1792 // to the new method
1793 code_base = method->code_base();
1794 code_length = method->code_size();
1795 bcp = code_base + bci;
1796 c = (Bytecodes::Code)(*bcp);
1797 bc_length = Bytecodes::length_for(c);
1798 assert(bc_length != 0, "sanity check");
1799 } // end we need ldc_w instead of ldc
1800 } // end if there is a mapped index
1801 } break;
1802
1803 // these bytecodes have a two-byte constant pool index
1804 case Bytecodes::_anewarray : // fall through
1805 case Bytecodes::_checkcast : // fall through
1806 case Bytecodes::_getfield : // fall through
1807 case Bytecodes::_getstatic : // fall through
1808 case Bytecodes::_instanceof : // fall through
1809 case Bytecodes::_invokedynamic : // fall through
1810 case Bytecodes::_invokeinterface: // fall through
1811 case Bytecodes::_invokespecial : // fall through
1812 case Bytecodes::_invokestatic : // fall through
1813 case Bytecodes::_invokevirtual : // fall through
1814 case Bytecodes::_ldc_w : // fall through
1815 case Bytecodes::_ldc2_w : // fall through
1816 case Bytecodes::_multianewarray : // fall through
1817 case Bytecodes::_new : // fall through
1818 case Bytecodes::_putfield : // fall through
1819 case Bytecodes::_putstatic :
1820 {
1821 address p = bcp + 1;
1822 int cp_index = Bytes::get_Java_u2(p);
1823 int new_index = find_new_index(cp_index);
1824 if (new_index != 0) {
1825 // the original index is mapped so update w/ new value
1826 RC_TRACE_WITH_THREAD(0x00080000, THREAD,
1827 ("%s@" INTPTR_FORMAT " old=%d, new=%d", Bytecodes::name(c),
1828 bcp, cp_index, new_index));
1829 // Rewriter::rewrite_method() uses put_native_u2() in this
1830 // situation because it is reusing the constant pool index
1831 // location for a native index into the ConstantPoolCache.
1832 // Since we are updating the constant pool index prior to
1833 // verification and ConstantPoolCache initialization, we
1834 // need to keep the new index in Java byte order.
1835 Bytes::put_Java_u2(p, new_index);
1836 }
1837 } break;
1838 }
1839 } // end for each bytecode
1840
1841 // We also need to rewrite the parameter name indexes, if there is
1842 // method parameter data present
1843 if(method->has_method_parameters()) {
1844 const int len = method->method_parameters_length();
1845 MethodParametersElement* elem = method->method_parameters_start();
1846
1847 for (int i = 0; i < len; i++) {
1848 const u2 cp_index = elem[i].name_cp_index;
1849 const u2 new_cp_index = find_new_index(cp_index);
1850 if (new_cp_index != 0) {
1851 elem[i].name_cp_index = new_cp_index;
1852 }
1853 }
1854 }
1855 } // end rewrite_cp_refs_in_method()
1856
1857
1858 // Rewrite constant pool references in the class_annotations field.
rewrite_cp_refs_in_class_annotations(instanceKlassHandle scratch_class,TRAPS)1859 bool VM_RedefineClasses::rewrite_cp_refs_in_class_annotations(
1860 instanceKlassHandle scratch_class, TRAPS) {
1861
1862 AnnotationArray* class_annotations = scratch_class->class_annotations();
1863 if (class_annotations == NULL || class_annotations->length() == 0) {
1864 // no class_annotations so nothing to do
1865 return true;
1866 }
1867
1868 RC_TRACE_WITH_THREAD(0x02000000, THREAD,
1869 ("class_annotations length=%d", class_annotations->length()));
1870
1871 int byte_i = 0; // byte index into class_annotations
1872 return rewrite_cp_refs_in_annotations_typeArray(class_annotations, byte_i,
1873 THREAD);
1874 }
1875
1876
1877 // Rewrite constant pool references in an annotations typeArray. This
1878 // "structure" is adapted from the RuntimeVisibleAnnotations_attribute
1879 // that is described in section 4.8.15 of the 2nd-edition of the VM spec:
1880 //
1881 // annotations_typeArray {
1882 // u2 num_annotations;
1883 // annotation annotations[num_annotations];
1884 // }
1885 //
rewrite_cp_refs_in_annotations_typeArray(AnnotationArray * annotations_typeArray,int & byte_i_ref,TRAPS)1886 bool VM_RedefineClasses::rewrite_cp_refs_in_annotations_typeArray(
1887 AnnotationArray* annotations_typeArray, int &byte_i_ref, TRAPS) {
1888
1889 if ((byte_i_ref + 2) > annotations_typeArray->length()) {
1890 // not enough room for num_annotations field
1891 RC_TRACE_WITH_THREAD(0x02000000, THREAD,
1892 ("length() is too small for num_annotations field"));
1893 return false;
1894 }
1895
1896 u2 num_annotations = Bytes::get_Java_u2((address)
1897 annotations_typeArray->adr_at(byte_i_ref));
1898 byte_i_ref += 2;
1899
1900 RC_TRACE_WITH_THREAD(0x02000000, THREAD,
1901 ("num_annotations=%d", num_annotations));
1902
1903 int calc_num_annotations = 0;
1904 for (; calc_num_annotations < num_annotations; calc_num_annotations++) {
1905 if (!rewrite_cp_refs_in_annotation_struct(annotations_typeArray,
1906 byte_i_ref, THREAD)) {
1907 RC_TRACE_WITH_THREAD(0x02000000, THREAD,
1908 ("bad annotation_struct at %d", calc_num_annotations));
1909 // propagate failure back to caller
1910 return false;
1911 }
1912 }
1913 assert(num_annotations == calc_num_annotations, "sanity check");
1914
1915 return true;
1916 } // end rewrite_cp_refs_in_annotations_typeArray()
1917
1918
1919 // Rewrite constant pool references in the annotation struct portion of
1920 // an annotations_typeArray. This "structure" is from section 4.8.15 of
1921 // the 2nd-edition of the VM spec:
1922 //
1923 // struct annotation {
1924 // u2 type_index;
1925 // u2 num_element_value_pairs;
1926 // {
1927 // u2 element_name_index;
1928 // element_value value;
1929 // } element_value_pairs[num_element_value_pairs];
1930 // }
1931 //
rewrite_cp_refs_in_annotation_struct(AnnotationArray * annotations_typeArray,int & byte_i_ref,TRAPS)1932 bool VM_RedefineClasses::rewrite_cp_refs_in_annotation_struct(
1933 AnnotationArray* annotations_typeArray, int &byte_i_ref, TRAPS) {
1934 if ((byte_i_ref + 2 + 2) > annotations_typeArray->length()) {
1935 // not enough room for smallest annotation_struct
1936 RC_TRACE_WITH_THREAD(0x02000000, THREAD,
1937 ("length() is too small for annotation_struct"));
1938 return false;
1939 }
1940
1941 u2 type_index = rewrite_cp_ref_in_annotation_data(annotations_typeArray,
1942 byte_i_ref, "mapped old type_index=%d", THREAD);
1943
1944 u2 num_element_value_pairs = Bytes::get_Java_u2((address)
1945 annotations_typeArray->adr_at(byte_i_ref));
1946 byte_i_ref += 2;
1947
1948 RC_TRACE_WITH_THREAD(0x02000000, THREAD,
1949 ("type_index=%d num_element_value_pairs=%d", type_index,
1950 num_element_value_pairs));
1951
1952 int calc_num_element_value_pairs = 0;
1953 for (; calc_num_element_value_pairs < num_element_value_pairs;
1954 calc_num_element_value_pairs++) {
1955 if ((byte_i_ref + 2) > annotations_typeArray->length()) {
1956 // not enough room for another element_name_index, let alone
1957 // the rest of another component
1958 RC_TRACE_WITH_THREAD(0x02000000, THREAD,
1959 ("length() is too small for element_name_index"));
1960 return false;
1961 }
1962
1963 u2 element_name_index = rewrite_cp_ref_in_annotation_data(
1964 annotations_typeArray, byte_i_ref,
1965 "mapped old element_name_index=%d", THREAD);
1966
1967 RC_TRACE_WITH_THREAD(0x02000000, THREAD,
1968 ("element_name_index=%d", element_name_index));
1969
1970 if (!rewrite_cp_refs_in_element_value(annotations_typeArray,
1971 byte_i_ref, THREAD)) {
1972 RC_TRACE_WITH_THREAD(0x02000000, THREAD,
1973 ("bad element_value at %d", calc_num_element_value_pairs));
1974 // propagate failure back to caller
1975 return false;
1976 }
1977 } // end for each component
1978 assert(num_element_value_pairs == calc_num_element_value_pairs,
1979 "sanity check");
1980
1981 return true;
1982 } // end rewrite_cp_refs_in_annotation_struct()
1983
1984
1985 // Rewrite a constant pool reference at the current position in
1986 // annotations_typeArray if needed. Returns the original constant
1987 // pool reference if a rewrite was not needed or the new constant
1988 // pool reference if a rewrite was needed.
1989 PRAGMA_DIAG_PUSH
1990 PRAGMA_FORMAT_NONLITERAL_IGNORED
rewrite_cp_ref_in_annotation_data(AnnotationArray * annotations_typeArray,int & byte_i_ref,const char * trace_mesg,TRAPS)1991 u2 VM_RedefineClasses::rewrite_cp_ref_in_annotation_data(
1992 AnnotationArray* annotations_typeArray, int &byte_i_ref,
1993 const char * trace_mesg, TRAPS) {
1994
1995 address cp_index_addr = (address)
1996 annotations_typeArray->adr_at(byte_i_ref);
1997 u2 old_cp_index = Bytes::get_Java_u2(cp_index_addr);
1998 u2 new_cp_index = find_new_index(old_cp_index);
1999 if (new_cp_index != 0) {
2000 RC_TRACE_WITH_THREAD(0x02000000, THREAD, (trace_mesg, old_cp_index));
2001 Bytes::put_Java_u2(cp_index_addr, new_cp_index);
2002 old_cp_index = new_cp_index;
2003 }
2004 byte_i_ref += 2;
2005 return old_cp_index;
2006 }
2007 PRAGMA_DIAG_POP
2008
2009
2010 // Rewrite constant pool references in the element_value portion of an
2011 // annotations_typeArray. This "structure" is from section 4.8.15.1 of
2012 // the 2nd-edition of the VM spec:
2013 //
2014 // struct element_value {
2015 // u1 tag;
2016 // union {
2017 // u2 const_value_index;
2018 // {
2019 // u2 type_name_index;
2020 // u2 const_name_index;
2021 // } enum_const_value;
2022 // u2 class_info_index;
2023 // annotation annotation_value;
2024 // struct {
2025 // u2 num_values;
2026 // element_value values[num_values];
2027 // } array_value;
2028 // } value;
2029 // }
2030 //
rewrite_cp_refs_in_element_value(AnnotationArray * annotations_typeArray,int & byte_i_ref,TRAPS)2031 bool VM_RedefineClasses::rewrite_cp_refs_in_element_value(
2032 AnnotationArray* annotations_typeArray, int &byte_i_ref, TRAPS) {
2033
2034 if ((byte_i_ref + 1) > annotations_typeArray->length()) {
2035 // not enough room for a tag let alone the rest of an element_value
2036 RC_TRACE_WITH_THREAD(0x02000000, THREAD,
2037 ("length() is too small for a tag"));
2038 return false;
2039 }
2040
2041 u1 tag = annotations_typeArray->at(byte_i_ref);
2042 byte_i_ref++;
2043 RC_TRACE_WITH_THREAD(0x02000000, THREAD, ("tag='%c'", tag));
2044
2045 switch (tag) {
2046 // These BaseType tag values are from Table 4.2 in VM spec:
2047 case 'B': // byte
2048 case 'C': // char
2049 case 'D': // double
2050 case 'F': // float
2051 case 'I': // int
2052 case 'J': // long
2053 case 'S': // short
2054 case 'Z': // boolean
2055
2056 // The remaining tag values are from Table 4.8 in the 2nd-edition of
2057 // the VM spec:
2058 case 's':
2059 {
2060 // For the above tag values (including the BaseType values),
2061 // value.const_value_index is right union field.
2062
2063 if ((byte_i_ref + 2) > annotations_typeArray->length()) {
2064 // not enough room for a const_value_index
2065 RC_TRACE_WITH_THREAD(0x02000000, THREAD,
2066 ("length() is too small for a const_value_index"));
2067 return false;
2068 }
2069
2070 u2 const_value_index = rewrite_cp_ref_in_annotation_data(
2071 annotations_typeArray, byte_i_ref,
2072 "mapped old const_value_index=%d", THREAD);
2073
2074 RC_TRACE_WITH_THREAD(0x02000000, THREAD,
2075 ("const_value_index=%d", const_value_index));
2076 } break;
2077
2078 case 'e':
2079 {
2080 // for the above tag value, value.enum_const_value is right union field
2081
2082 if ((byte_i_ref + 4) > annotations_typeArray->length()) {
2083 // not enough room for a enum_const_value
2084 RC_TRACE_WITH_THREAD(0x02000000, THREAD,
2085 ("length() is too small for a enum_const_value"));
2086 return false;
2087 }
2088
2089 u2 type_name_index = rewrite_cp_ref_in_annotation_data(
2090 annotations_typeArray, byte_i_ref,
2091 "mapped old type_name_index=%d", THREAD);
2092
2093 u2 const_name_index = rewrite_cp_ref_in_annotation_data(
2094 annotations_typeArray, byte_i_ref,
2095 "mapped old const_name_index=%d", THREAD);
2096
2097 RC_TRACE_WITH_THREAD(0x02000000, THREAD,
2098 ("type_name_index=%d const_name_index=%d", type_name_index,
2099 const_name_index));
2100 } break;
2101
2102 case 'c':
2103 {
2104 // for the above tag value, value.class_info_index is right union field
2105
2106 if ((byte_i_ref + 2) > annotations_typeArray->length()) {
2107 // not enough room for a class_info_index
2108 RC_TRACE_WITH_THREAD(0x02000000, THREAD,
2109 ("length() is too small for a class_info_index"));
2110 return false;
2111 }
2112
2113 u2 class_info_index = rewrite_cp_ref_in_annotation_data(
2114 annotations_typeArray, byte_i_ref,
2115 "mapped old class_info_index=%d", THREAD);
2116
2117 RC_TRACE_WITH_THREAD(0x02000000, THREAD,
2118 ("class_info_index=%d", class_info_index));
2119 } break;
2120
2121 case '@':
2122 // For the above tag value, value.attr_value is the right union
2123 // field. This is a nested annotation.
2124 if (!rewrite_cp_refs_in_annotation_struct(annotations_typeArray,
2125 byte_i_ref, THREAD)) {
2126 // propagate failure back to caller
2127 return false;
2128 }
2129 break;
2130
2131 case '[':
2132 {
2133 if ((byte_i_ref + 2) > annotations_typeArray->length()) {
2134 // not enough room for a num_values field
2135 RC_TRACE_WITH_THREAD(0x02000000, THREAD,
2136 ("length() is too small for a num_values field"));
2137 return false;
2138 }
2139
2140 // For the above tag value, value.array_value is the right union
2141 // field. This is an array of nested element_value.
2142 u2 num_values = Bytes::get_Java_u2((address)
2143 annotations_typeArray->adr_at(byte_i_ref));
2144 byte_i_ref += 2;
2145 RC_TRACE_WITH_THREAD(0x02000000, THREAD, ("num_values=%d", num_values));
2146
2147 int calc_num_values = 0;
2148 for (; calc_num_values < num_values; calc_num_values++) {
2149 if (!rewrite_cp_refs_in_element_value(
2150 annotations_typeArray, byte_i_ref, THREAD)) {
2151 RC_TRACE_WITH_THREAD(0x02000000, THREAD,
2152 ("bad nested element_value at %d", calc_num_values));
2153 // propagate failure back to caller
2154 return false;
2155 }
2156 }
2157 assert(num_values == calc_num_values, "sanity check");
2158 } break;
2159
2160 default:
2161 RC_TRACE_WITH_THREAD(0x02000000, THREAD, ("bad tag=0x%x", tag));
2162 return false;
2163 } // end decode tag field
2164
2165 return true;
2166 } // end rewrite_cp_refs_in_element_value()
2167
2168
2169 // Rewrite constant pool references in a fields_annotations field.
rewrite_cp_refs_in_fields_annotations(instanceKlassHandle scratch_class,TRAPS)2170 bool VM_RedefineClasses::rewrite_cp_refs_in_fields_annotations(
2171 instanceKlassHandle scratch_class, TRAPS) {
2172
2173 Array<AnnotationArray*>* fields_annotations = scratch_class->fields_annotations();
2174
2175 if (fields_annotations == NULL || fields_annotations->length() == 0) {
2176 // no fields_annotations so nothing to do
2177 return true;
2178 }
2179
2180 RC_TRACE_WITH_THREAD(0x02000000, THREAD,
2181 ("fields_annotations length=%d", fields_annotations->length()));
2182
2183 for (int i = 0; i < fields_annotations->length(); i++) {
2184 AnnotationArray* field_annotations = fields_annotations->at(i);
2185 if (field_annotations == NULL || field_annotations->length() == 0) {
2186 // this field does not have any annotations so skip it
2187 continue;
2188 }
2189
2190 int byte_i = 0; // byte index into field_annotations
2191 if (!rewrite_cp_refs_in_annotations_typeArray(field_annotations, byte_i,
2192 THREAD)) {
2193 RC_TRACE_WITH_THREAD(0x02000000, THREAD,
2194 ("bad field_annotations at %d", i));
2195 // propagate failure back to caller
2196 return false;
2197 }
2198 }
2199
2200 return true;
2201 } // end rewrite_cp_refs_in_fields_annotations()
2202
2203
2204 // Rewrite constant pool references in a methods_annotations field.
rewrite_cp_refs_in_methods_annotations(instanceKlassHandle scratch_class,TRAPS)2205 bool VM_RedefineClasses::rewrite_cp_refs_in_methods_annotations(
2206 instanceKlassHandle scratch_class, TRAPS) {
2207
2208 for (int i = 0; i < scratch_class->methods()->length(); i++) {
2209 Method* m = scratch_class->methods()->at(i);
2210 AnnotationArray* method_annotations = m->constMethod()->method_annotations();
2211
2212 if (method_annotations == NULL || method_annotations->length() == 0) {
2213 // this method does not have any annotations so skip it
2214 continue;
2215 }
2216
2217 int byte_i = 0; // byte index into method_annotations
2218 if (!rewrite_cp_refs_in_annotations_typeArray(method_annotations, byte_i,
2219 THREAD)) {
2220 RC_TRACE_WITH_THREAD(0x02000000, THREAD,
2221 ("bad method_annotations at %d", i));
2222 // propagate failure back to caller
2223 return false;
2224 }
2225 }
2226
2227 return true;
2228 } // end rewrite_cp_refs_in_methods_annotations()
2229
2230
2231 // Rewrite constant pool references in a methods_parameter_annotations
2232 // field. This "structure" is adapted from the
2233 // RuntimeVisibleParameterAnnotations_attribute described in section
2234 // 4.8.17 of the 2nd-edition of the VM spec:
2235 //
2236 // methods_parameter_annotations_typeArray {
2237 // u1 num_parameters;
2238 // {
2239 // u2 num_annotations;
2240 // annotation annotations[num_annotations];
2241 // } parameter_annotations[num_parameters];
2242 // }
2243 //
rewrite_cp_refs_in_methods_parameter_annotations(instanceKlassHandle scratch_class,TRAPS)2244 bool VM_RedefineClasses::rewrite_cp_refs_in_methods_parameter_annotations(
2245 instanceKlassHandle scratch_class, TRAPS) {
2246
2247 for (int i = 0; i < scratch_class->methods()->length(); i++) {
2248 Method* m = scratch_class->methods()->at(i);
2249 AnnotationArray* method_parameter_annotations = m->constMethod()->parameter_annotations();
2250 if (method_parameter_annotations == NULL
2251 || method_parameter_annotations->length() == 0) {
2252 // this method does not have any parameter annotations so skip it
2253 continue;
2254 }
2255
2256 if (method_parameter_annotations->length() < 1) {
2257 // not enough room for a num_parameters field
2258 RC_TRACE_WITH_THREAD(0x02000000, THREAD,
2259 ("length() is too small for a num_parameters field at %d", i));
2260 return false;
2261 }
2262
2263 int byte_i = 0; // byte index into method_parameter_annotations
2264
2265 u1 num_parameters = method_parameter_annotations->at(byte_i);
2266 byte_i++;
2267
2268 RC_TRACE_WITH_THREAD(0x02000000, THREAD,
2269 ("num_parameters=%d", num_parameters));
2270
2271 int calc_num_parameters = 0;
2272 for (; calc_num_parameters < num_parameters; calc_num_parameters++) {
2273 if (!rewrite_cp_refs_in_annotations_typeArray(
2274 method_parameter_annotations, byte_i, THREAD)) {
2275 RC_TRACE_WITH_THREAD(0x02000000, THREAD,
2276 ("bad method_parameter_annotations at %d", calc_num_parameters));
2277 // propagate failure back to caller
2278 return false;
2279 }
2280 }
2281 assert(num_parameters == calc_num_parameters, "sanity check");
2282 }
2283
2284 return true;
2285 } // end rewrite_cp_refs_in_methods_parameter_annotations()
2286
2287
2288 // Rewrite constant pool references in a methods_default_annotations
2289 // field. This "structure" is adapted from the AnnotationDefault_attribute
2290 // that is described in section 4.8.19 of the 2nd-edition of the VM spec:
2291 //
2292 // methods_default_annotations_typeArray {
2293 // element_value default_value;
2294 // }
2295 //
rewrite_cp_refs_in_methods_default_annotations(instanceKlassHandle scratch_class,TRAPS)2296 bool VM_RedefineClasses::rewrite_cp_refs_in_methods_default_annotations(
2297 instanceKlassHandle scratch_class, TRAPS) {
2298
2299 for (int i = 0; i < scratch_class->methods()->length(); i++) {
2300 Method* m = scratch_class->methods()->at(i);
2301 AnnotationArray* method_default_annotations = m->constMethod()->default_annotations();
2302 if (method_default_annotations == NULL
2303 || method_default_annotations->length() == 0) {
2304 // this method does not have any default annotations so skip it
2305 continue;
2306 }
2307
2308 int byte_i = 0; // byte index into method_default_annotations
2309
2310 if (!rewrite_cp_refs_in_element_value(
2311 method_default_annotations, byte_i, THREAD)) {
2312 RC_TRACE_WITH_THREAD(0x02000000, THREAD,
2313 ("bad default element_value at %d", i));
2314 // propagate failure back to caller
2315 return false;
2316 }
2317 }
2318
2319 return true;
2320 } // end rewrite_cp_refs_in_methods_default_annotations()
2321
2322
2323 // Rewrite constant pool references in a class_type_annotations field.
rewrite_cp_refs_in_class_type_annotations(instanceKlassHandle scratch_class,TRAPS)2324 bool VM_RedefineClasses::rewrite_cp_refs_in_class_type_annotations(
2325 instanceKlassHandle scratch_class, TRAPS) {
2326
2327 AnnotationArray* class_type_annotations = scratch_class->class_type_annotations();
2328 if (class_type_annotations == NULL || class_type_annotations->length() == 0) {
2329 // no class_type_annotations so nothing to do
2330 return true;
2331 }
2332
2333 RC_TRACE_WITH_THREAD(0x02000000, THREAD,
2334 ("class_type_annotations length=%d", class_type_annotations->length()));
2335
2336 int byte_i = 0; // byte index into class_type_annotations
2337 return rewrite_cp_refs_in_type_annotations_typeArray(class_type_annotations,
2338 byte_i, "ClassFile", THREAD);
2339 } // end rewrite_cp_refs_in_class_type_annotations()
2340
2341
2342 // Rewrite constant pool references in a fields_type_annotations field.
rewrite_cp_refs_in_fields_type_annotations(instanceKlassHandle scratch_class,TRAPS)2343 bool VM_RedefineClasses::rewrite_cp_refs_in_fields_type_annotations(
2344 instanceKlassHandle scratch_class, TRAPS) {
2345
2346 Array<AnnotationArray*>* fields_type_annotations = scratch_class->fields_type_annotations();
2347 if (fields_type_annotations == NULL || fields_type_annotations->length() == 0) {
2348 // no fields_type_annotations so nothing to do
2349 return true;
2350 }
2351
2352 RC_TRACE_WITH_THREAD(0x02000000, THREAD,
2353 ("fields_type_annotations length=%d", fields_type_annotations->length()));
2354
2355 for (int i = 0; i < fields_type_annotations->length(); i++) {
2356 AnnotationArray* field_type_annotations = fields_type_annotations->at(i);
2357 if (field_type_annotations == NULL || field_type_annotations->length() == 0) {
2358 // this field does not have any annotations so skip it
2359 continue;
2360 }
2361
2362 int byte_i = 0; // byte index into field_type_annotations
2363 if (!rewrite_cp_refs_in_type_annotations_typeArray(field_type_annotations,
2364 byte_i, "field_info", THREAD)) {
2365 RC_TRACE_WITH_THREAD(0x02000000, THREAD,
2366 ("bad field_type_annotations at %d", i));
2367 // propagate failure back to caller
2368 return false;
2369 }
2370 }
2371
2372 return true;
2373 } // end rewrite_cp_refs_in_fields_type_annotations()
2374
2375
2376 // Rewrite constant pool references in a methods_type_annotations field.
rewrite_cp_refs_in_methods_type_annotations(instanceKlassHandle scratch_class,TRAPS)2377 bool VM_RedefineClasses::rewrite_cp_refs_in_methods_type_annotations(
2378 instanceKlassHandle scratch_class, TRAPS) {
2379
2380 for (int i = 0; i < scratch_class->methods()->length(); i++) {
2381 Method* m = scratch_class->methods()->at(i);
2382 AnnotationArray* method_type_annotations = m->constMethod()->type_annotations();
2383
2384 if (method_type_annotations == NULL || method_type_annotations->length() == 0) {
2385 // this method does not have any annotations so skip it
2386 continue;
2387 }
2388
2389 RC_TRACE_WITH_THREAD(0x02000000, THREAD,
2390 ("methods type_annotations length=%d", method_type_annotations->length()));
2391
2392 int byte_i = 0; // byte index into method_type_annotations
2393 if (!rewrite_cp_refs_in_type_annotations_typeArray(method_type_annotations,
2394 byte_i, "method_info", THREAD)) {
2395 RC_TRACE_WITH_THREAD(0x02000000, THREAD,
2396 ("bad method_type_annotations at %d", i));
2397 // propagate failure back to caller
2398 return false;
2399 }
2400 }
2401
2402 return true;
2403 } // end rewrite_cp_refs_in_methods_type_annotations()
2404
2405
2406 // Rewrite constant pool references in a type_annotations
2407 // field. This "structure" is adapted from the
2408 // RuntimeVisibleTypeAnnotations_attribute described in
2409 // section 4.7.20 of the Java SE 8 Edition of the VM spec:
2410 //
2411 // type_annotations_typeArray {
2412 // u2 num_annotations;
2413 // type_annotation annotations[num_annotations];
2414 // }
2415 //
rewrite_cp_refs_in_type_annotations_typeArray(AnnotationArray * type_annotations_typeArray,int & byte_i_ref,const char * location_mesg,TRAPS)2416 bool VM_RedefineClasses::rewrite_cp_refs_in_type_annotations_typeArray(
2417 AnnotationArray* type_annotations_typeArray, int &byte_i_ref,
2418 const char * location_mesg, TRAPS) {
2419
2420 if ((byte_i_ref + 2) > type_annotations_typeArray->length()) {
2421 // not enough room for num_annotations field
2422 RC_TRACE_WITH_THREAD(0x02000000, THREAD,
2423 ("length() is too small for num_annotations field"));
2424 return false;
2425 }
2426
2427 u2 num_annotations = Bytes::get_Java_u2((address)
2428 type_annotations_typeArray->adr_at(byte_i_ref));
2429 byte_i_ref += 2;
2430
2431 RC_TRACE_WITH_THREAD(0x02000000, THREAD,
2432 ("num_type_annotations=%d", num_annotations));
2433
2434 int calc_num_annotations = 0;
2435 for (; calc_num_annotations < num_annotations; calc_num_annotations++) {
2436 if (!rewrite_cp_refs_in_type_annotation_struct(type_annotations_typeArray,
2437 byte_i_ref, location_mesg, THREAD)) {
2438 RC_TRACE_WITH_THREAD(0x02000000, THREAD,
2439 ("bad type_annotation_struct at %d", calc_num_annotations));
2440 // propagate failure back to caller
2441 return false;
2442 }
2443 }
2444 assert(num_annotations == calc_num_annotations, "sanity check");
2445
2446 if (byte_i_ref != type_annotations_typeArray->length()) {
2447 RC_TRACE_WITH_THREAD(0x02000000, THREAD,
2448 ("read wrong amount of bytes at end of processing "
2449 "type_annotations_typeArray (%d of %d bytes were read)",
2450 byte_i_ref, type_annotations_typeArray->length()));
2451 return false;
2452 }
2453
2454 return true;
2455 } // end rewrite_cp_refs_in_type_annotations_typeArray()
2456
2457
2458 // Rewrite constant pool references in a type_annotation
2459 // field. This "structure" is adapted from the
2460 // RuntimeVisibleTypeAnnotations_attribute described in
2461 // section 4.7.20 of the Java SE 8 Edition of the VM spec:
2462 //
2463 // type_annotation {
2464 // u1 target_type;
2465 // union {
2466 // type_parameter_target;
2467 // supertype_target;
2468 // type_parameter_bound_target;
2469 // empty_target;
2470 // method_formal_parameter_target;
2471 // throws_target;
2472 // localvar_target;
2473 // catch_target;
2474 // offset_target;
2475 // type_argument_target;
2476 // } target_info;
2477 // type_path target_path;
2478 // annotation anno;
2479 // }
2480 //
rewrite_cp_refs_in_type_annotation_struct(AnnotationArray * type_annotations_typeArray,int & byte_i_ref,const char * location_mesg,TRAPS)2481 bool VM_RedefineClasses::rewrite_cp_refs_in_type_annotation_struct(
2482 AnnotationArray* type_annotations_typeArray, int &byte_i_ref,
2483 const char * location_mesg, TRAPS) {
2484
2485 if (!skip_type_annotation_target(type_annotations_typeArray,
2486 byte_i_ref, location_mesg, THREAD)) {
2487 return false;
2488 }
2489
2490 if (!skip_type_annotation_type_path(type_annotations_typeArray,
2491 byte_i_ref, THREAD)) {
2492 return false;
2493 }
2494
2495 if (!rewrite_cp_refs_in_annotation_struct(type_annotations_typeArray,
2496 byte_i_ref, THREAD)) {
2497 return false;
2498 }
2499
2500 return true;
2501 } // end rewrite_cp_refs_in_type_annotation_struct()
2502
2503
2504 // Read, verify and skip over the target_type and target_info part
2505 // so that rewriting can continue in the later parts of the struct.
2506 //
2507 // u1 target_type;
2508 // union {
2509 // type_parameter_target;
2510 // supertype_target;
2511 // type_parameter_bound_target;
2512 // empty_target;
2513 // method_formal_parameter_target;
2514 // throws_target;
2515 // localvar_target;
2516 // catch_target;
2517 // offset_target;
2518 // type_argument_target;
2519 // } target_info;
2520 //
skip_type_annotation_target(AnnotationArray * type_annotations_typeArray,int & byte_i_ref,const char * location_mesg,TRAPS)2521 bool VM_RedefineClasses::skip_type_annotation_target(
2522 AnnotationArray* type_annotations_typeArray, int &byte_i_ref,
2523 const char * location_mesg, TRAPS) {
2524
2525 if ((byte_i_ref + 1) > type_annotations_typeArray->length()) {
2526 // not enough room for a target_type let alone the rest of a type_annotation
2527 RC_TRACE_WITH_THREAD(0x02000000, THREAD,
2528 ("length() is too small for a target_type"));
2529 return false;
2530 }
2531
2532 u1 target_type = type_annotations_typeArray->at(byte_i_ref);
2533 byte_i_ref += 1;
2534 RC_TRACE_WITH_THREAD(0x02000000, THREAD, ("target_type=0x%.2x", target_type));
2535 RC_TRACE_WITH_THREAD(0x02000000, THREAD, ("location=%s", location_mesg));
2536
2537 // Skip over target_info
2538 switch (target_type) {
2539 case 0x00:
2540 // kind: type parameter declaration of generic class or interface
2541 // location: ClassFile
2542 case 0x01:
2543 // kind: type parameter declaration of generic method or constructor
2544 // location: method_info
2545
2546 {
2547 // struct:
2548 // type_parameter_target {
2549 // u1 type_parameter_index;
2550 // }
2551 //
2552 if ((byte_i_ref + 1) > type_annotations_typeArray->length()) {
2553 RC_TRACE_WITH_THREAD(0x02000000, THREAD,
2554 ("length() is too small for a type_parameter_target"));
2555 return false;
2556 }
2557
2558 u1 type_parameter_index = type_annotations_typeArray->at(byte_i_ref);
2559 byte_i_ref += 1;
2560
2561 RC_TRACE_WITH_THREAD(0x02000000, THREAD,
2562 ("type_parameter_target: type_parameter_index=%d",
2563 type_parameter_index));
2564 } break;
2565
2566 case 0x10:
2567 // kind: type in extends clause of class or interface declaration
2568 // (including the direct superclass of an anonymous class declaration),
2569 // or in implements clause of interface declaration
2570 // location: ClassFile
2571
2572 {
2573 // struct:
2574 // supertype_target {
2575 // u2 supertype_index;
2576 // }
2577 //
2578 if ((byte_i_ref + 2) > type_annotations_typeArray->length()) {
2579 RC_TRACE_WITH_THREAD(0x02000000, THREAD,
2580 ("length() is too small for a supertype_target"));
2581 return false;
2582 }
2583
2584 u2 supertype_index = Bytes::get_Java_u2((address)
2585 type_annotations_typeArray->adr_at(byte_i_ref));
2586 byte_i_ref += 2;
2587
2588 RC_TRACE_WITH_THREAD(0x02000000, THREAD,
2589 ("supertype_target: supertype_index=%d", supertype_index));
2590 } break;
2591
2592 case 0x11:
2593 // kind: type in bound of type parameter declaration of generic class or interface
2594 // location: ClassFile
2595 case 0x12:
2596 // kind: type in bound of type parameter declaration of generic method or constructor
2597 // location: method_info
2598
2599 {
2600 // struct:
2601 // type_parameter_bound_target {
2602 // u1 type_parameter_index;
2603 // u1 bound_index;
2604 // }
2605 //
2606 if ((byte_i_ref + 2) > type_annotations_typeArray->length()) {
2607 RC_TRACE_WITH_THREAD(0x02000000, THREAD,
2608 ("length() is too small for a type_parameter_bound_target"));
2609 return false;
2610 }
2611
2612 u1 type_parameter_index = type_annotations_typeArray->at(byte_i_ref);
2613 byte_i_ref += 1;
2614 u1 bound_index = type_annotations_typeArray->at(byte_i_ref);
2615 byte_i_ref += 1;
2616
2617 RC_TRACE_WITH_THREAD(0x02000000, THREAD,
2618 ("type_parameter_bound_target: type_parameter_index=%d, bound_index=%d",
2619 type_parameter_index, bound_index));
2620 } break;
2621
2622 case 0x13:
2623 // kind: type in field declaration
2624 // location: field_info
2625 case 0x14:
2626 // kind: return type of method, or type of newly constructed object
2627 // location: method_info
2628 case 0x15:
2629 // kind: receiver type of method or constructor
2630 // location: method_info
2631
2632 {
2633 // struct:
2634 // empty_target {
2635 // }
2636 //
2637 RC_TRACE_WITH_THREAD(0x02000000, THREAD,
2638 ("empty_target"));
2639 } break;
2640
2641 case 0x16:
2642 // kind: type in formal parameter declaration of method, constructor, or lambda expression
2643 // location: method_info
2644
2645 {
2646 // struct:
2647 // formal_parameter_target {
2648 // u1 formal_parameter_index;
2649 // }
2650 //
2651 if ((byte_i_ref + 1) > type_annotations_typeArray->length()) {
2652 RC_TRACE_WITH_THREAD(0x02000000, THREAD,
2653 ("length() is too small for a formal_parameter_target"));
2654 return false;
2655 }
2656
2657 u1 formal_parameter_index = type_annotations_typeArray->at(byte_i_ref);
2658 byte_i_ref += 1;
2659
2660 RC_TRACE_WITH_THREAD(0x02000000, THREAD,
2661 ("formal_parameter_target: formal_parameter_index=%d",
2662 formal_parameter_index));
2663 } break;
2664
2665 case 0x17:
2666 // kind: type in throws clause of method or constructor
2667 // location: method_info
2668
2669 {
2670 // struct:
2671 // throws_target {
2672 // u2 throws_type_index
2673 // }
2674 //
2675 if ((byte_i_ref + 2) > type_annotations_typeArray->length()) {
2676 RC_TRACE_WITH_THREAD(0x02000000, THREAD,
2677 ("length() is too small for a throws_target"));
2678 return false;
2679 }
2680
2681 u2 throws_type_index = Bytes::get_Java_u2((address)
2682 type_annotations_typeArray->adr_at(byte_i_ref));
2683 byte_i_ref += 2;
2684
2685 RC_TRACE_WITH_THREAD(0x02000000, THREAD,
2686 ("throws_target: throws_type_index=%d", throws_type_index));
2687 } break;
2688
2689 case 0x40:
2690 // kind: type in local variable declaration
2691 // location: Code
2692 case 0x41:
2693 // kind: type in resource variable declaration
2694 // location: Code
2695
2696 {
2697 // struct:
2698 // localvar_target {
2699 // u2 table_length;
2700 // struct {
2701 // u2 start_pc;
2702 // u2 length;
2703 // u2 index;
2704 // } table[table_length];
2705 // }
2706 //
2707 if ((byte_i_ref + 2) > type_annotations_typeArray->length()) {
2708 // not enough room for a table_length let alone the rest of a localvar_target
2709 RC_TRACE_WITH_THREAD(0x02000000, THREAD,
2710 ("length() is too small for a localvar_target table_length"));
2711 return false;
2712 }
2713
2714 u2 table_length = Bytes::get_Java_u2((address)
2715 type_annotations_typeArray->adr_at(byte_i_ref));
2716 byte_i_ref += 2;
2717
2718 RC_TRACE_WITH_THREAD(0x02000000, THREAD,
2719 ("localvar_target: table_length=%d", table_length));
2720
2721 int table_struct_size = 2 + 2 + 2; // 3 u2 variables per table entry
2722 int table_size = table_length * table_struct_size;
2723
2724 if ((byte_i_ref + table_size) > type_annotations_typeArray->length()) {
2725 // not enough room for a table
2726 RC_TRACE_WITH_THREAD(0x02000000, THREAD,
2727 ("length() is too small for a table array of length %d", table_length));
2728 return false;
2729 }
2730
2731 // Skip over table
2732 byte_i_ref += table_size;
2733 } break;
2734
2735 case 0x42:
2736 // kind: type in exception parameter declaration
2737 // location: Code
2738
2739 {
2740 // struct:
2741 // catch_target {
2742 // u2 exception_table_index;
2743 // }
2744 //
2745 if ((byte_i_ref + 2) > type_annotations_typeArray->length()) {
2746 RC_TRACE_WITH_THREAD(0x02000000, THREAD,
2747 ("length() is too small for a catch_target"));
2748 return false;
2749 }
2750
2751 u2 exception_table_index = Bytes::get_Java_u2((address)
2752 type_annotations_typeArray->adr_at(byte_i_ref));
2753 byte_i_ref += 2;
2754
2755 RC_TRACE_WITH_THREAD(0x02000000, THREAD,
2756 ("catch_target: exception_table_index=%d", exception_table_index));
2757 } break;
2758
2759 case 0x43:
2760 // kind: type in instanceof expression
2761 // location: Code
2762 case 0x44:
2763 // kind: type in new expression
2764 // location: Code
2765 case 0x45:
2766 // kind: type in method reference expression using ::new
2767 // location: Code
2768 case 0x46:
2769 // kind: type in method reference expression using ::Identifier
2770 // location: Code
2771
2772 {
2773 // struct:
2774 // offset_target {
2775 // u2 offset;
2776 // }
2777 //
2778 if ((byte_i_ref + 2) > type_annotations_typeArray->length()) {
2779 RC_TRACE_WITH_THREAD(0x02000000, THREAD,
2780 ("length() is too small for a offset_target"));
2781 return false;
2782 }
2783
2784 u2 offset = Bytes::get_Java_u2((address)
2785 type_annotations_typeArray->adr_at(byte_i_ref));
2786 byte_i_ref += 2;
2787
2788 RC_TRACE_WITH_THREAD(0x02000000, THREAD,
2789 ("offset_target: offset=%d", offset));
2790 } break;
2791
2792 case 0x47:
2793 // kind: type in cast expression
2794 // location: Code
2795 case 0x48:
2796 // kind: type argument for generic constructor in new expression or
2797 // explicit constructor invocation statement
2798 // location: Code
2799 case 0x49:
2800 // kind: type argument for generic method in method invocation expression
2801 // location: Code
2802 case 0x4A:
2803 // kind: type argument for generic constructor in method reference expression using ::new
2804 // location: Code
2805 case 0x4B:
2806 // kind: type argument for generic method in method reference expression using ::Identifier
2807 // location: Code
2808
2809 {
2810 // struct:
2811 // type_argument_target {
2812 // u2 offset;
2813 // u1 type_argument_index;
2814 // }
2815 //
2816 if ((byte_i_ref + 3) > type_annotations_typeArray->length()) {
2817 RC_TRACE_WITH_THREAD(0x02000000, THREAD,
2818 ("length() is too small for a type_argument_target"));
2819 return false;
2820 }
2821
2822 u2 offset = Bytes::get_Java_u2((address)
2823 type_annotations_typeArray->adr_at(byte_i_ref));
2824 byte_i_ref += 2;
2825 u1 type_argument_index = type_annotations_typeArray->at(byte_i_ref);
2826 byte_i_ref += 1;
2827
2828 RC_TRACE_WITH_THREAD(0x02000000, THREAD,
2829 ("type_argument_target: offset=%d, type_argument_index=%d",
2830 offset, type_argument_index));
2831 } break;
2832
2833 default:
2834 RC_TRACE_WITH_THREAD(0x02000000, THREAD,
2835 ("unknown target_type"));
2836 #ifdef ASSERT
2837 ShouldNotReachHere();
2838 #endif
2839 return false;
2840 }
2841
2842 return true;
2843 } // end skip_type_annotation_target()
2844
2845
2846 // Read, verify and skip over the type_path part so that rewriting
2847 // can continue in the later parts of the struct.
2848 //
2849 // type_path {
2850 // u1 path_length;
2851 // {
2852 // u1 type_path_kind;
2853 // u1 type_argument_index;
2854 // } path[path_length];
2855 // }
2856 //
skip_type_annotation_type_path(AnnotationArray * type_annotations_typeArray,int & byte_i_ref,TRAPS)2857 bool VM_RedefineClasses::skip_type_annotation_type_path(
2858 AnnotationArray* type_annotations_typeArray, int &byte_i_ref, TRAPS) {
2859
2860 if ((byte_i_ref + 1) > type_annotations_typeArray->length()) {
2861 // not enough room for a path_length let alone the rest of the type_path
2862 RC_TRACE_WITH_THREAD(0x02000000, THREAD,
2863 ("length() is too small for a type_path"));
2864 return false;
2865 }
2866
2867 u1 path_length = type_annotations_typeArray->at(byte_i_ref);
2868 byte_i_ref += 1;
2869
2870 RC_TRACE_WITH_THREAD(0x02000000, THREAD,
2871 ("type_path: path_length=%d", path_length));
2872
2873 int calc_path_length = 0;
2874 for (; calc_path_length < path_length; calc_path_length++) {
2875 if ((byte_i_ref + 1 + 1) > type_annotations_typeArray->length()) {
2876 // not enough room for a path
2877 RC_TRACE_WITH_THREAD(0x02000000, THREAD,
2878 ("length() is too small for path entry %d of %d",
2879 calc_path_length, path_length));
2880 return false;
2881 }
2882
2883 u1 type_path_kind = type_annotations_typeArray->at(byte_i_ref);
2884 byte_i_ref += 1;
2885 u1 type_argument_index = type_annotations_typeArray->at(byte_i_ref);
2886 byte_i_ref += 1;
2887
2888 RC_TRACE_WITH_THREAD(0x02000000, THREAD,
2889 ("type_path: path[%d]: type_path_kind=%d, type_argument_index=%d",
2890 calc_path_length, type_path_kind, type_argument_index));
2891
2892 if (type_path_kind > 3 || (type_path_kind != 3 && type_argument_index != 0)) {
2893 // not enough room for a path
2894 RC_TRACE_WITH_THREAD(0x02000000, THREAD,
2895 ("inconsistent type_path values"));
2896 return false;
2897 }
2898 }
2899 assert(path_length == calc_path_length, "sanity check");
2900
2901 return true;
2902 } // end skip_type_annotation_type_path()
2903
2904
2905 // Rewrite constant pool references in the method's stackmap table.
2906 // These "structures" are adapted from the StackMapTable_attribute that
2907 // is described in section 4.8.4 of the 6.0 version of the VM spec
2908 // (dated 2005.10.26):
2909 // file:///net/quincunx.sfbay/export/gbracha/ClassFile-Java6.pdf
2910 //
2911 // stack_map {
2912 // u2 number_of_entries;
2913 // stack_map_frame entries[number_of_entries];
2914 // }
2915 //
rewrite_cp_refs_in_stack_map_table(methodHandle method,TRAPS)2916 void VM_RedefineClasses::rewrite_cp_refs_in_stack_map_table(
2917 methodHandle method, TRAPS) {
2918
2919 if (!method->has_stackmap_table()) {
2920 return;
2921 }
2922
2923 AnnotationArray* stackmap_data = method->stackmap_data();
2924 address stackmap_p = (address)stackmap_data->adr_at(0);
2925 address stackmap_end = stackmap_p + stackmap_data->length();
2926
2927 assert(stackmap_p + 2 <= stackmap_end, "no room for number_of_entries");
2928 u2 number_of_entries = Bytes::get_Java_u2(stackmap_p);
2929 stackmap_p += 2;
2930
2931 RC_TRACE_WITH_THREAD(0x04000000, THREAD,
2932 ("number_of_entries=%u", number_of_entries));
2933
2934 // walk through each stack_map_frame
2935 u2 calc_number_of_entries = 0;
2936 for (; calc_number_of_entries < number_of_entries; calc_number_of_entries++) {
2937 // The stack_map_frame structure is a u1 frame_type followed by
2938 // 0 or more bytes of data:
2939 //
2940 // union stack_map_frame {
2941 // same_frame;
2942 // same_locals_1_stack_item_frame;
2943 // same_locals_1_stack_item_frame_extended;
2944 // chop_frame;
2945 // same_frame_extended;
2946 // append_frame;
2947 // full_frame;
2948 // }
2949
2950 assert(stackmap_p + 1 <= stackmap_end, "no room for frame_type");
2951 // The Linux compiler does not like frame_type to be u1 or u2. It
2952 // issues the following warning for the first if-statement below:
2953 //
2954 // "warning: comparison is always true due to limited range of data type"
2955 //
2956 u4 frame_type = *stackmap_p;
2957 stackmap_p++;
2958
2959 // same_frame {
2960 // u1 frame_type = SAME; /* 0-63 */
2961 // }
2962 if (frame_type >= 0 && frame_type <= 63) {
2963 // nothing more to do for same_frame
2964 }
2965
2966 // same_locals_1_stack_item_frame {
2967 // u1 frame_type = SAME_LOCALS_1_STACK_ITEM; /* 64-127 */
2968 // verification_type_info stack[1];
2969 // }
2970 else if (frame_type >= 64 && frame_type <= 127) {
2971 rewrite_cp_refs_in_verification_type_info(stackmap_p, stackmap_end,
2972 calc_number_of_entries, frame_type, THREAD);
2973 }
2974
2975 // reserved for future use
2976 else if (frame_type >= 128 && frame_type <= 246) {
2977 // nothing more to do for reserved frame_types
2978 }
2979
2980 // same_locals_1_stack_item_frame_extended {
2981 // u1 frame_type = SAME_LOCALS_1_STACK_ITEM_EXTENDED; /* 247 */
2982 // u2 offset_delta;
2983 // verification_type_info stack[1];
2984 // }
2985 else if (frame_type == 247) {
2986 stackmap_p += 2;
2987 rewrite_cp_refs_in_verification_type_info(stackmap_p, stackmap_end,
2988 calc_number_of_entries, frame_type, THREAD);
2989 }
2990
2991 // chop_frame {
2992 // u1 frame_type = CHOP; /* 248-250 */
2993 // u2 offset_delta;
2994 // }
2995 else if (frame_type >= 248 && frame_type <= 250) {
2996 stackmap_p += 2;
2997 }
2998
2999 // same_frame_extended {
3000 // u1 frame_type = SAME_FRAME_EXTENDED; /* 251*/
3001 // u2 offset_delta;
3002 // }
3003 else if (frame_type == 251) {
3004 stackmap_p += 2;
3005 }
3006
3007 // append_frame {
3008 // u1 frame_type = APPEND; /* 252-254 */
3009 // u2 offset_delta;
3010 // verification_type_info locals[frame_type - 251];
3011 // }
3012 else if (frame_type >= 252 && frame_type <= 254) {
3013 assert(stackmap_p + 2 <= stackmap_end,
3014 "no room for offset_delta");
3015 stackmap_p += 2;
3016 u1 len = frame_type - 251;
3017 for (u1 i = 0; i < len; i++) {
3018 rewrite_cp_refs_in_verification_type_info(stackmap_p, stackmap_end,
3019 calc_number_of_entries, frame_type, THREAD);
3020 }
3021 }
3022
3023 // full_frame {
3024 // u1 frame_type = FULL_FRAME; /* 255 */
3025 // u2 offset_delta;
3026 // u2 number_of_locals;
3027 // verification_type_info locals[number_of_locals];
3028 // u2 number_of_stack_items;
3029 // verification_type_info stack[number_of_stack_items];
3030 // }
3031 else if (frame_type == 255) {
3032 assert(stackmap_p + 2 + 2 <= stackmap_end,
3033 "no room for smallest full_frame");
3034 stackmap_p += 2;
3035
3036 u2 number_of_locals = Bytes::get_Java_u2(stackmap_p);
3037 stackmap_p += 2;
3038
3039 for (u2 locals_i = 0; locals_i < number_of_locals; locals_i++) {
3040 rewrite_cp_refs_in_verification_type_info(stackmap_p, stackmap_end,
3041 calc_number_of_entries, frame_type, THREAD);
3042 }
3043
3044 // Use the largest size for the number_of_stack_items, but only get
3045 // the right number of bytes.
3046 u2 number_of_stack_items = Bytes::get_Java_u2(stackmap_p);
3047 stackmap_p += 2;
3048
3049 for (u2 stack_i = 0; stack_i < number_of_stack_items; stack_i++) {
3050 rewrite_cp_refs_in_verification_type_info(stackmap_p, stackmap_end,
3051 calc_number_of_entries, frame_type, THREAD);
3052 }
3053 }
3054 } // end while there is a stack_map_frame
3055 assert(number_of_entries == calc_number_of_entries, "sanity check");
3056 } // end rewrite_cp_refs_in_stack_map_table()
3057
3058
3059 // Rewrite constant pool references in the verification type info
3060 // portion of the method's stackmap table. These "structures" are
3061 // adapted from the StackMapTable_attribute that is described in
3062 // section 4.8.4 of the 6.0 version of the VM spec (dated 2005.10.26):
3063 // file:///net/quincunx.sfbay/export/gbracha/ClassFile-Java6.pdf
3064 //
3065 // The verification_type_info structure is a u1 tag followed by 0 or
3066 // more bytes of data:
3067 //
3068 // union verification_type_info {
3069 // Top_variable_info;
3070 // Integer_variable_info;
3071 // Float_variable_info;
3072 // Long_variable_info;
3073 // Double_variable_info;
3074 // Null_variable_info;
3075 // UninitializedThis_variable_info;
3076 // Object_variable_info;
3077 // Uninitialized_variable_info;
3078 // }
3079 //
rewrite_cp_refs_in_verification_type_info(address & stackmap_p_ref,address stackmap_end,u2 frame_i,u1 frame_type,TRAPS)3080 void VM_RedefineClasses::rewrite_cp_refs_in_verification_type_info(
3081 address& stackmap_p_ref, address stackmap_end, u2 frame_i,
3082 u1 frame_type, TRAPS) {
3083
3084 assert(stackmap_p_ref + 1 <= stackmap_end, "no room for tag");
3085 u1 tag = *stackmap_p_ref;
3086 stackmap_p_ref++;
3087
3088 switch (tag) {
3089 // Top_variable_info {
3090 // u1 tag = ITEM_Top; /* 0 */
3091 // }
3092 // verificationType.hpp has zero as ITEM_Bogus instead of ITEM_Top
3093 case 0: // fall through
3094
3095 // Integer_variable_info {
3096 // u1 tag = ITEM_Integer; /* 1 */
3097 // }
3098 case ITEM_Integer: // fall through
3099
3100 // Float_variable_info {
3101 // u1 tag = ITEM_Float; /* 2 */
3102 // }
3103 case ITEM_Float: // fall through
3104
3105 // Double_variable_info {
3106 // u1 tag = ITEM_Double; /* 3 */
3107 // }
3108 case ITEM_Double: // fall through
3109
3110 // Long_variable_info {
3111 // u1 tag = ITEM_Long; /* 4 */
3112 // }
3113 case ITEM_Long: // fall through
3114
3115 // Null_variable_info {
3116 // u1 tag = ITEM_Null; /* 5 */
3117 // }
3118 case ITEM_Null: // fall through
3119
3120 // UninitializedThis_variable_info {
3121 // u1 tag = ITEM_UninitializedThis; /* 6 */
3122 // }
3123 case ITEM_UninitializedThis:
3124 // nothing more to do for the above tag types
3125 break;
3126
3127 // Object_variable_info {
3128 // u1 tag = ITEM_Object; /* 7 */
3129 // u2 cpool_index;
3130 // }
3131 case ITEM_Object:
3132 {
3133 assert(stackmap_p_ref + 2 <= stackmap_end, "no room for cpool_index");
3134 u2 cpool_index = Bytes::get_Java_u2(stackmap_p_ref);
3135 u2 new_cp_index = find_new_index(cpool_index);
3136 if (new_cp_index != 0) {
3137 RC_TRACE_WITH_THREAD(0x04000000, THREAD,
3138 ("mapped old cpool_index=%d", cpool_index));
3139 Bytes::put_Java_u2(stackmap_p_ref, new_cp_index);
3140 cpool_index = new_cp_index;
3141 }
3142 stackmap_p_ref += 2;
3143
3144 RC_TRACE_WITH_THREAD(0x04000000, THREAD,
3145 ("frame_i=%u, frame_type=%u, cpool_index=%d", frame_i,
3146 frame_type, cpool_index));
3147 } break;
3148
3149 // Uninitialized_variable_info {
3150 // u1 tag = ITEM_Uninitialized; /* 8 */
3151 // u2 offset;
3152 // }
3153 case ITEM_Uninitialized:
3154 assert(stackmap_p_ref + 2 <= stackmap_end, "no room for offset");
3155 stackmap_p_ref += 2;
3156 break;
3157
3158 default:
3159 RC_TRACE_WITH_THREAD(0x04000000, THREAD,
3160 ("frame_i=%u, frame_type=%u, bad tag=0x%x", frame_i, frame_type, tag));
3161 ShouldNotReachHere();
3162 break;
3163 } // end switch (tag)
3164 } // end rewrite_cp_refs_in_verification_type_info()
3165
3166
3167 // Change the constant pool associated with klass scratch_class to
3168 // scratch_cp. If shrink is true, then scratch_cp_length elements
3169 // are copied from scratch_cp to a smaller constant pool and the
3170 // smaller constant pool is associated with scratch_class.
set_new_constant_pool(ClassLoaderData * loader_data,instanceKlassHandle scratch_class,constantPoolHandle scratch_cp,int scratch_cp_length,TRAPS)3171 void VM_RedefineClasses::set_new_constant_pool(
3172 ClassLoaderData* loader_data,
3173 instanceKlassHandle scratch_class, constantPoolHandle scratch_cp,
3174 int scratch_cp_length, TRAPS) {
3175 assert(scratch_cp->length() >= scratch_cp_length, "sanity check");
3176
3177 // scratch_cp is a merged constant pool and has enough space for a
3178 // worst case merge situation. We want to associate the minimum
3179 // sized constant pool with the klass to save space.
3180 ConstantPool* cp = ConstantPool::allocate(loader_data, scratch_cp_length, CHECK);
3181 constantPoolHandle smaller_cp(THREAD, cp);
3182
3183 // preserve version() value in the smaller copy
3184 int version = scratch_cp->version();
3185 assert(version != 0, "sanity check");
3186 smaller_cp->set_version(version);
3187
3188 // attach klass to new constant pool
3189 // reference to the cp holder is needed for copy_operands()
3190 smaller_cp->set_pool_holder(scratch_class());
3191
3192 scratch_cp->copy_cp_to(1, scratch_cp_length - 1, smaller_cp, 1, THREAD);
3193 if (HAS_PENDING_EXCEPTION) {
3194 // Exception is handled in the caller
3195 loader_data->add_to_deallocate_list(smaller_cp());
3196 return;
3197 }
3198 scratch_cp = smaller_cp;
3199
3200 // attach new constant pool to klass
3201 scratch_class->set_constants(scratch_cp());
3202
3203 int i; // for portability
3204
3205 // update each field in klass to use new constant pool indices as needed
3206 for (JavaFieldStream fs(scratch_class); !fs.done(); fs.next()) {
3207 jshort cur_index = fs.name_index();
3208 jshort new_index = find_new_index(cur_index);
3209 if (new_index != 0) {
3210 RC_TRACE_WITH_THREAD(0x00080000, THREAD,
3211 ("field-name_index change: %d to %d", cur_index, new_index));
3212 fs.set_name_index(new_index);
3213 }
3214 cur_index = fs.signature_index();
3215 new_index = find_new_index(cur_index);
3216 if (new_index != 0) {
3217 RC_TRACE_WITH_THREAD(0x00080000, THREAD,
3218 ("field-signature_index change: %d to %d", cur_index, new_index));
3219 fs.set_signature_index(new_index);
3220 }
3221 cur_index = fs.initval_index();
3222 new_index = find_new_index(cur_index);
3223 if (new_index != 0) {
3224 RC_TRACE_WITH_THREAD(0x00080000, THREAD,
3225 ("field-initval_index change: %d to %d", cur_index, new_index));
3226 fs.set_initval_index(new_index);
3227 }
3228 cur_index = fs.generic_signature_index();
3229 new_index = find_new_index(cur_index);
3230 if (new_index != 0) {
3231 RC_TRACE_WITH_THREAD(0x00080000, THREAD,
3232 ("field-generic_signature change: %d to %d", cur_index, new_index));
3233 fs.set_generic_signature_index(new_index);
3234 }
3235 } // end for each field
3236
3237 // Update constant pool indices in the inner classes info to use
3238 // new constant indices as needed. The inner classes info is a
3239 // quadruple:
3240 // (inner_class_info, outer_class_info, inner_name, inner_access_flags)
3241 InnerClassesIterator iter(scratch_class);
3242 for (; !iter.done(); iter.next()) {
3243 int cur_index = iter.inner_class_info_index();
3244 if (cur_index == 0) {
3245 continue; // JVM spec. allows null inner class refs so skip it
3246 }
3247 int new_index = find_new_index(cur_index);
3248 if (new_index != 0) {
3249 RC_TRACE_WITH_THREAD(0x00080000, THREAD,
3250 ("inner_class_info change: %d to %d", cur_index, new_index));
3251 iter.set_inner_class_info_index(new_index);
3252 }
3253 cur_index = iter.outer_class_info_index();
3254 new_index = find_new_index(cur_index);
3255 if (new_index != 0) {
3256 RC_TRACE_WITH_THREAD(0x00080000, THREAD,
3257 ("outer_class_info change: %d to %d", cur_index, new_index));
3258 iter.set_outer_class_info_index(new_index);
3259 }
3260 cur_index = iter.inner_name_index();
3261 new_index = find_new_index(cur_index);
3262 if (new_index != 0) {
3263 RC_TRACE_WITH_THREAD(0x00080000, THREAD,
3264 ("inner_name change: %d to %d", cur_index, new_index));
3265 iter.set_inner_name_index(new_index);
3266 }
3267 } // end for each inner class
3268
3269 // Attach each method in klass to the new constant pool and update
3270 // to use new constant pool indices as needed:
3271 Array<Method*>* methods = scratch_class->methods();
3272 for (i = methods->length() - 1; i >= 0; i--) {
3273 methodHandle method(THREAD, methods->at(i));
3274 method->set_constants(scratch_cp());
3275
3276 int new_index = find_new_index(method->name_index());
3277 if (new_index != 0) {
3278 RC_TRACE_WITH_THREAD(0x00080000, THREAD,
3279 ("method-name_index change: %d to %d", method->name_index(),
3280 new_index));
3281 method->set_name_index(new_index);
3282 }
3283 new_index = find_new_index(method->signature_index());
3284 if (new_index != 0) {
3285 RC_TRACE_WITH_THREAD(0x00080000, THREAD,
3286 ("method-signature_index change: %d to %d",
3287 method->signature_index(), new_index));
3288 method->set_signature_index(new_index);
3289 }
3290 new_index = find_new_index(method->generic_signature_index());
3291 if (new_index != 0) {
3292 RC_TRACE_WITH_THREAD(0x00080000, THREAD,
3293 ("method-generic_signature_index change: %d to %d",
3294 method->generic_signature_index(), new_index));
3295 method->set_generic_signature_index(new_index);
3296 }
3297
3298 // Update constant pool indices in the method's checked exception
3299 // table to use new constant indices as needed.
3300 int cext_length = method->checked_exceptions_length();
3301 if (cext_length > 0) {
3302 CheckedExceptionElement * cext_table =
3303 method->checked_exceptions_start();
3304 for (int j = 0; j < cext_length; j++) {
3305 int cur_index = cext_table[j].class_cp_index;
3306 int new_index = find_new_index(cur_index);
3307 if (new_index != 0) {
3308 RC_TRACE_WITH_THREAD(0x00080000, THREAD,
3309 ("cext-class_cp_index change: %d to %d", cur_index, new_index));
3310 cext_table[j].class_cp_index = (u2)new_index;
3311 }
3312 } // end for each checked exception table entry
3313 } // end if there are checked exception table entries
3314
3315 // Update each catch type index in the method's exception table
3316 // to use new constant pool indices as needed. The exception table
3317 // holds quadruple entries of the form:
3318 // (beg_bci, end_bci, handler_bci, klass_index)
3319
3320 ExceptionTable ex_table(method());
3321 int ext_length = ex_table.length();
3322
3323 for (int j = 0; j < ext_length; j ++) {
3324 int cur_index = ex_table.catch_type_index(j);
3325 int new_index = find_new_index(cur_index);
3326 if (new_index != 0) {
3327 RC_TRACE_WITH_THREAD(0x00080000, THREAD,
3328 ("ext-klass_index change: %d to %d", cur_index, new_index));
3329 ex_table.set_catch_type_index(j, new_index);
3330 }
3331 } // end for each exception table entry
3332
3333 // Update constant pool indices in the method's local variable
3334 // table to use new constant indices as needed. The local variable
3335 // table hold sextuple entries of the form:
3336 // (start_pc, length, name_index, descriptor_index, signature_index, slot)
3337 int lvt_length = method->localvariable_table_length();
3338 if (lvt_length > 0) {
3339 LocalVariableTableElement * lv_table =
3340 method->localvariable_table_start();
3341 for (int j = 0; j < lvt_length; j++) {
3342 int cur_index = lv_table[j].name_cp_index;
3343 int new_index = find_new_index(cur_index);
3344 if (new_index != 0) {
3345 RC_TRACE_WITH_THREAD(0x00080000, THREAD,
3346 ("lvt-name_cp_index change: %d to %d", cur_index, new_index));
3347 lv_table[j].name_cp_index = (u2)new_index;
3348 }
3349 cur_index = lv_table[j].descriptor_cp_index;
3350 new_index = find_new_index(cur_index);
3351 if (new_index != 0) {
3352 RC_TRACE_WITH_THREAD(0x00080000, THREAD,
3353 ("lvt-descriptor_cp_index change: %d to %d", cur_index,
3354 new_index));
3355 lv_table[j].descriptor_cp_index = (u2)new_index;
3356 }
3357 cur_index = lv_table[j].signature_cp_index;
3358 new_index = find_new_index(cur_index);
3359 if (new_index != 0) {
3360 RC_TRACE_WITH_THREAD(0x00080000, THREAD,
3361 ("lvt-signature_cp_index change: %d to %d", cur_index, new_index));
3362 lv_table[j].signature_cp_index = (u2)new_index;
3363 }
3364 } // end for each local variable table entry
3365 } // end if there are local variable table entries
3366
3367 rewrite_cp_refs_in_stack_map_table(method, THREAD);
3368 } // end for each method
3369 } // end set_new_constant_pool()
3370
3371
3372 // Unevolving classes may point to methods of the_class directly
3373 // from their constant pool caches, itables, and/or vtables. We
3374 // use the ClassLoaderDataGraph::classes_do() facility and this helper
3375 // to fix up these pointers.
3376
3377 // Adjust cpools and vtables closure
do_klass(Klass * k)3378 void VM_RedefineClasses::AdjustCpoolCacheAndVtable::do_klass(Klass* k) {
3379
3380 // This is a very busy routine. We don't want too much tracing
3381 // printed out.
3382 bool trace_name_printed = false;
3383 InstanceKlass *the_class = InstanceKlass::cast(_the_class_oop);
3384
3385 // Very noisy: only enable this call if you are trying to determine
3386 // that a specific class gets found by this routine.
3387 // RC_TRACE macro has an embedded ResourceMark
3388 // RC_TRACE_WITH_THREAD(0x00100000, THREAD,
3389 // ("adjust check: name=%s", k->external_name()));
3390 // trace_name_printed = true;
3391
3392 // If the class being redefined is java.lang.Object, we need to fix all
3393 // array class vtables also
3394 if (k->oop_is_array() && _the_class_oop == SystemDictionary::Object_klass()) {
3395 k->vtable()->adjust_method_entries(the_class, &trace_name_printed);
3396
3397 } else if (k->oop_is_instance()) {
3398 HandleMark hm(_thread);
3399 InstanceKlass *ik = InstanceKlass::cast(k);
3400
3401 // HotSpot specific optimization! HotSpot does not currently
3402 // support delegation from the bootstrap class loader to a
3403 // user-defined class loader. This means that if the bootstrap
3404 // class loader is the initiating class loader, then it will also
3405 // be the defining class loader. This also means that classes
3406 // loaded by the bootstrap class loader cannot refer to classes
3407 // loaded by a user-defined class loader. Note: a user-defined
3408 // class loader can delegate to the bootstrap class loader.
3409 //
3410 // If the current class being redefined has a user-defined class
3411 // loader as its defining class loader, then we can skip all
3412 // classes loaded by the bootstrap class loader.
3413 bool is_user_defined =
3414 InstanceKlass::cast(_the_class_oop)->class_loader() != NULL;
3415 if (is_user_defined && ik->class_loader() == NULL) {
3416 return;
3417 }
3418
3419 // Fix the vtable embedded in the_class and subclasses of the_class,
3420 // if one exists. We discard scratch_class and we don't keep an
3421 // InstanceKlass around to hold obsolete methods so we don't have
3422 // any other InstanceKlass embedded vtables to update. The vtable
3423 // holds the Method*s for virtual (but not final) methods.
3424 // Default methods, or concrete methods in interfaces are stored
3425 // in the vtable, so if an interface changes we need to check
3426 // adjust_method_entries() for every InstanceKlass, which will also
3427 // adjust the default method vtable indices.
3428 // We also need to adjust any default method entries that are
3429 // not yet in the vtable, because the vtable setup is in progress.
3430 // This must be done after we adjust the default_methods and
3431 // default_vtable_indices for methods already in the vtable.
3432 // If redefining Unsafe, walk all the vtables looking for entries.
3433 if (ik->vtable_length() > 0 && (_the_class_oop->is_interface()
3434 || _the_class_oop == SystemDictionary::misc_Unsafe_klass()
3435 || ik->is_subtype_of(_the_class_oop))) {
3436 // ik->vtable() creates a wrapper object; rm cleans it up
3437 ResourceMark rm(_thread);
3438
3439 ik->vtable()->adjust_method_entries(the_class, &trace_name_printed);
3440 ik->adjust_default_methods(the_class, &trace_name_printed);
3441 }
3442
3443 // If the current class has an itable and we are either redefining an
3444 // interface or if the current class is a subclass of the_class, then
3445 // we potentially have to fix the itable. If we are redefining an
3446 // interface, then we have to call adjust_method_entries() for
3447 // every InstanceKlass that has an itable since there isn't a
3448 // subclass relationship between an interface and an InstanceKlass.
3449 // If redefining Unsafe, walk all the itables looking for entries.
3450 if (ik->itable_length() > 0 && (_the_class_oop->is_interface()
3451 || _the_class_oop == SystemDictionary::misc_Unsafe_klass()
3452 || ik->is_subclass_of(_the_class_oop))) {
3453 // ik->itable() creates a wrapper object; rm cleans it up
3454 ResourceMark rm(_thread);
3455
3456 ik->itable()->adjust_method_entries(the_class, &trace_name_printed);
3457 }
3458
3459 // The constant pools in other classes (other_cp) can refer to
3460 // methods in the_class. We have to update method information in
3461 // other_cp's cache. If other_cp has a previous version, then we
3462 // have to repeat the process for each previous version. The
3463 // constant pool cache holds the Method*s for non-virtual
3464 // methods and for virtual, final methods.
3465 //
3466 // Special case: if the current class is the_class, then new_cp
3467 // has already been attached to the_class and old_cp has already
3468 // been added as a previous version. The new_cp doesn't have any
3469 // cached references to old methods so it doesn't need to be
3470 // updated. We can simply start with the previous version(s) in
3471 // that case.
3472 constantPoolHandle other_cp;
3473 ConstantPoolCache* cp_cache;
3474
3475 if (ik != _the_class_oop) {
3476 // this klass' constant pool cache may need adjustment
3477 other_cp = constantPoolHandle(ik->constants());
3478 cp_cache = other_cp->cache();
3479 if (cp_cache != NULL) {
3480 cp_cache->adjust_method_entries(the_class, &trace_name_printed);
3481 }
3482 }
3483
3484 // the previous versions' constant pool caches may need adjustment
3485 for (InstanceKlass* pv_node = ik->previous_versions();
3486 pv_node != NULL;
3487 pv_node = pv_node->previous_versions()) {
3488 cp_cache = pv_node->constants()->cache();
3489 if (cp_cache != NULL) {
3490 cp_cache->adjust_method_entries(pv_node, &trace_name_printed);
3491 }
3492 }
3493 }
3494 }
3495
update_jmethod_ids()3496 void VM_RedefineClasses::update_jmethod_ids() {
3497 for (int j = 0; j < _matching_methods_length; ++j) {
3498 Method* old_method = _matching_old_methods[j];
3499 jmethodID jmid = old_method->find_jmethod_id_or_null();
3500 if (jmid != NULL) {
3501 // There is a jmethodID, change it to point to the new method
3502 methodHandle new_method_h(_matching_new_methods[j]);
3503 Method::change_method_associated_with_jmethod_id(jmid, new_method_h());
3504 assert(Method::resolve_jmethod_id(jmid) == _matching_new_methods[j],
3505 "should be replaced");
3506 }
3507 }
3508 }
3509
check_methods_and_mark_as_obsolete()3510 int VM_RedefineClasses::check_methods_and_mark_as_obsolete() {
3511 int emcp_method_count = 0;
3512 int obsolete_count = 0;
3513 int old_index = 0;
3514 for (int j = 0; j < _matching_methods_length; ++j, ++old_index) {
3515 Method* old_method = _matching_old_methods[j];
3516 Method* new_method = _matching_new_methods[j];
3517 Method* old_array_method;
3518
3519 // Maintain an old_index into the _old_methods array by skipping
3520 // deleted methods
3521 while ((old_array_method = _old_methods->at(old_index)) != old_method) {
3522 ++old_index;
3523 }
3524
3525 if (MethodComparator::methods_EMCP(old_method, new_method)) {
3526 // The EMCP definition from JSR-163 requires the bytecodes to be
3527 // the same with the exception of constant pool indices which may
3528 // differ. However, the constants referred to by those indices
3529 // must be the same.
3530 //
3531 // We use methods_EMCP() for comparison since constant pool
3532 // merging can remove duplicate constant pool entries that were
3533 // present in the old method and removed from the rewritten new
3534 // method. A faster binary comparison function would consider the
3535 // old and new methods to be different when they are actually
3536 // EMCP.
3537 //
3538 // The old and new methods are EMCP and you would think that we
3539 // could get rid of one of them here and now and save some space.
3540 // However, the concept of EMCP only considers the bytecodes and
3541 // the constant pool entries in the comparison. Other things,
3542 // e.g., the line number table (LNT) or the local variable table
3543 // (LVT) don't count in the comparison. So the new (and EMCP)
3544 // method can have a new LNT that we need so we can't just
3545 // overwrite the new method with the old method.
3546 //
3547 // When this routine is called, we have already attached the new
3548 // methods to the_class so the old methods are effectively
3549 // overwritten. However, if an old method is still executing,
3550 // then the old method cannot be collected until sometime after
3551 // the old method call has returned. So the overwriting of old
3552 // methods by new methods will save us space except for those
3553 // (hopefully few) old methods that are still executing.
3554 //
3555 // A method refers to a ConstMethod* and this presents another
3556 // possible avenue to space savings. The ConstMethod* in the
3557 // new method contains possibly new attributes (LNT, LVT, etc).
3558 // At first glance, it seems possible to save space by replacing
3559 // the ConstMethod* in the old method with the ConstMethod*
3560 // from the new method. The old and new methods would share the
3561 // same ConstMethod* and we would save the space occupied by
3562 // the old ConstMethod*. However, the ConstMethod* contains
3563 // a back reference to the containing method. Sharing the
3564 // ConstMethod* between two methods could lead to confusion in
3565 // the code that uses the back reference. This would lead to
3566 // brittle code that could be broken in non-obvious ways now or
3567 // in the future.
3568 //
3569 // Another possibility is to copy the ConstMethod* from the new
3570 // method to the old method and then overwrite the new method with
3571 // the old method. Since the ConstMethod* contains the bytecodes
3572 // for the method embedded in the oop, this option would change
3573 // the bytecodes out from under any threads executing the old
3574 // method and make the thread's bcp invalid. Since EMCP requires
3575 // that the bytecodes be the same modulo constant pool indices, it
3576 // is straight forward to compute the correct new bcp in the new
3577 // ConstMethod* from the old bcp in the old ConstMethod*. The
3578 // time consuming part would be searching all the frames in all
3579 // of the threads to find all of the calls to the old method.
3580 //
3581 // It looks like we will have to live with the limited savings
3582 // that we get from effectively overwriting the old methods
3583 // when the new methods are attached to the_class.
3584
3585 // Count number of methods that are EMCP. The method will be marked
3586 // old but not obsolete if it is EMCP.
3587 emcp_method_count++;
3588
3589 // An EMCP method is _not_ obsolete. An obsolete method has a
3590 // different jmethodID than the current method. An EMCP method
3591 // has the same jmethodID as the current method. Having the
3592 // same jmethodID for all EMCP versions of a method allows for
3593 // a consistent view of the EMCP methods regardless of which
3594 // EMCP method you happen to have in hand. For example, a
3595 // breakpoint set in one EMCP method will work for all EMCP
3596 // versions of the method including the current one.
3597 } else {
3598 // mark obsolete methods as such
3599 old_method->set_is_obsolete();
3600 obsolete_count++;
3601
3602 // obsolete methods need a unique idnum so they become new entries in
3603 // the jmethodID cache in InstanceKlass
3604 assert(old_method->method_idnum() == new_method->method_idnum(), "must match");
3605 u2 num = InstanceKlass::cast(_the_class_oop)->next_method_idnum();
3606 if (num != ConstMethod::UNSET_IDNUM) {
3607 old_method->set_method_idnum(num);
3608 }
3609
3610 // With tracing we try not to "yack" too much. The position of
3611 // this trace assumes there are fewer obsolete methods than
3612 // EMCP methods.
3613 RC_TRACE(0x00000100, ("mark %s(%s) as obsolete",
3614 old_method->name()->as_C_string(),
3615 old_method->signature()->as_C_string()));
3616 }
3617 old_method->set_is_old();
3618 }
3619 for (int i = 0; i < _deleted_methods_length; ++i) {
3620 Method* old_method = _deleted_methods[i];
3621
3622 assert(!old_method->has_vtable_index(),
3623 "cannot delete methods with vtable entries");;
3624
3625 // Mark all deleted methods as old, obsolete and deleted
3626 old_method->set_is_deleted();
3627 old_method->set_is_old();
3628 old_method->set_is_obsolete();
3629 ++obsolete_count;
3630 // With tracing we try not to "yack" too much. The position of
3631 // this trace assumes there are fewer obsolete methods than
3632 // EMCP methods.
3633 RC_TRACE(0x00000100, ("mark deleted %s(%s) as obsolete",
3634 old_method->name()->as_C_string(),
3635 old_method->signature()->as_C_string()));
3636 }
3637 assert((emcp_method_count + obsolete_count) == _old_methods->length(),
3638 "sanity check");
3639 RC_TRACE(0x00000100, ("EMCP_cnt=%d, obsolete_cnt=%d", emcp_method_count,
3640 obsolete_count));
3641 return emcp_method_count;
3642 }
3643
3644 // This internal class transfers the native function registration from old methods
3645 // to new methods. It is designed to handle both the simple case of unchanged
3646 // native methods and the complex cases of native method prefixes being added and/or
3647 // removed.
3648 // It expects only to be used during the VM_RedefineClasses op (a safepoint).
3649 //
3650 // This class is used after the new methods have been installed in "the_class".
3651 //
3652 // So, for example, the following must be handled. Where 'm' is a method and
3653 // a number followed by an underscore is a prefix.
3654 //
3655 // Old Name New Name
3656 // Simple transfer to new method m -> m
3657 // Add prefix m -> 1_m
3658 // Remove prefix 1_m -> m
3659 // Simultaneous add of prefixes m -> 3_2_1_m
3660 // Simultaneous removal of prefixes 3_2_1_m -> m
3661 // Simultaneous add and remove 1_m -> 2_m
3662 // Same, caused by prefix removal only 3_2_1_m -> 3_2_m
3663 //
3664 class TransferNativeFunctionRegistration {
3665 private:
3666 instanceKlassHandle the_class;
3667 int prefix_count;
3668 char** prefixes;
3669
3670 // Recursively search the binary tree of possibly prefixed method names.
3671 // Iteration could be used if all agents were well behaved. Full tree walk is
3672 // more resilent to agents not cleaning up intermediate methods.
3673 // Branch at each depth in the binary tree is:
3674 // (1) without the prefix.
3675 // (2) with the prefix.
3676 // where 'prefix' is the prefix at that 'depth' (first prefix, second prefix,...)
search_prefix_name_space(int depth,char * name_str,size_t name_len,Symbol * signature)3677 Method* search_prefix_name_space(int depth, char* name_str, size_t name_len,
3678 Symbol* signature) {
3679 TempNewSymbol name_symbol = SymbolTable::probe(name_str, (int)name_len);
3680 if (name_symbol != NULL) {
3681 Method* method = the_class()->lookup_method(name_symbol, signature);
3682 if (method != NULL) {
3683 // Even if prefixed, intermediate methods must exist.
3684 if (method->is_native()) {
3685 // Wahoo, we found a (possibly prefixed) version of the method, return it.
3686 return method;
3687 }
3688 if (depth < prefix_count) {
3689 // Try applying further prefixes (other than this one).
3690 method = search_prefix_name_space(depth+1, name_str, name_len, signature);
3691 if (method != NULL) {
3692 return method; // found
3693 }
3694
3695 // Try adding this prefix to the method name and see if it matches
3696 // another method name.
3697 char* prefix = prefixes[depth];
3698 size_t prefix_len = strlen(prefix);
3699 size_t trial_len = name_len + prefix_len;
3700 char* trial_name_str = NEW_RESOURCE_ARRAY(char, trial_len + 1);
3701 strcpy(trial_name_str, prefix);
3702 strcat(trial_name_str, name_str);
3703 method = search_prefix_name_space(depth+1, trial_name_str, trial_len,
3704 signature);
3705 if (method != NULL) {
3706 // If found along this branch, it was prefixed, mark as such
3707 method->set_is_prefixed_native();
3708 return method; // found
3709 }
3710 }
3711 }
3712 }
3713 return NULL; // This whole branch bore nothing
3714 }
3715
3716 // Return the method name with old prefixes stripped away.
method_name_without_prefixes(Method * method)3717 char* method_name_without_prefixes(Method* method) {
3718 Symbol* name = method->name();
3719 char* name_str = name->as_utf8();
3720
3721 // Old prefixing may be defunct, strip prefixes, if any.
3722 for (int i = prefix_count-1; i >= 0; i--) {
3723 char* prefix = prefixes[i];
3724 size_t prefix_len = strlen(prefix);
3725 if (strncmp(prefix, name_str, prefix_len) == 0) {
3726 name_str += prefix_len;
3727 }
3728 }
3729 return name_str;
3730 }
3731
3732 // Strip any prefixes off the old native method, then try to find a
3733 // (possibly prefixed) new native that matches it.
strip_and_search_for_new_native(Method * method)3734 Method* strip_and_search_for_new_native(Method* method) {
3735 ResourceMark rm;
3736 char* name_str = method_name_without_prefixes(method);
3737 return search_prefix_name_space(0, name_str, strlen(name_str),
3738 method->signature());
3739 }
3740
3741 public:
3742
3743 // Construct a native method transfer processor for this class.
TransferNativeFunctionRegistration(instanceKlassHandle _the_class)3744 TransferNativeFunctionRegistration(instanceKlassHandle _the_class) {
3745 assert(SafepointSynchronize::is_at_safepoint(), "sanity check");
3746
3747 the_class = _the_class;
3748 prefixes = JvmtiExport::get_all_native_method_prefixes(&prefix_count);
3749 }
3750
3751 // Attempt to transfer any of the old or deleted methods that are native
transfer_registrations(Method ** old_methods,int methods_length)3752 void transfer_registrations(Method** old_methods, int methods_length) {
3753 for (int j = 0; j < methods_length; j++) {
3754 Method* old_method = old_methods[j];
3755
3756 if (old_method->is_native() && old_method->has_native_function()) {
3757 Method* new_method = strip_and_search_for_new_native(old_method);
3758 if (new_method != NULL) {
3759 // Actually set the native function in the new method.
3760 // Redefine does not send events (except CFLH), certainly not this
3761 // behind the scenes re-registration.
3762 new_method->set_native_function(old_method->native_function(),
3763 !Method::native_bind_event_is_interesting);
3764 }
3765 }
3766 }
3767 }
3768 };
3769
3770 // Don't lose the association between a native method and its JNI function.
transfer_old_native_function_registrations(instanceKlassHandle the_class)3771 void VM_RedefineClasses::transfer_old_native_function_registrations(instanceKlassHandle the_class) {
3772 TransferNativeFunctionRegistration transfer(the_class);
3773 transfer.transfer_registrations(_deleted_methods, _deleted_methods_length);
3774 transfer.transfer_registrations(_matching_old_methods, _matching_methods_length);
3775 }
3776
3777 // Deoptimize all compiled code that depends on this class.
3778 //
3779 // If the can_redefine_classes capability is obtained in the onload
3780 // phase then the compiler has recorded all dependencies from startup.
3781 // In that case we need only deoptimize and throw away all compiled code
3782 // that depends on the class.
3783 //
3784 // If can_redefine_classes is obtained sometime after the onload
3785 // phase then the dependency information may be incomplete. In that case
3786 // the first call to RedefineClasses causes all compiled code to be
3787 // thrown away. As can_redefine_classes has been obtained then
3788 // all future compilations will record dependencies so second and
3789 // subsequent calls to RedefineClasses need only throw away code
3790 // that depends on the class.
3791 //
flush_dependent_code(instanceKlassHandle k_h,TRAPS)3792 void VM_RedefineClasses::flush_dependent_code(instanceKlassHandle k_h, TRAPS) {
3793 assert_locked_or_safepoint(Compile_lock);
3794
3795 // All dependencies have been recorded from startup or this is a second or
3796 // subsequent use of RedefineClasses
3797 if (JvmtiExport::all_dependencies_are_recorded()) {
3798 Universe::flush_evol_dependents_on(k_h);
3799 } else {
3800 CodeCache::mark_all_nmethods_for_deoptimization();
3801
3802 ResourceMark rm(THREAD);
3803 DeoptimizationMarker dm;
3804
3805 // Deoptimize all activations depending on marked nmethods
3806 Deoptimization::deoptimize_dependents();
3807
3808 // Make the dependent methods not entrant
3809 CodeCache::make_marked_nmethods_not_entrant();
3810
3811 // From now on we know that the dependency information is complete
3812 JvmtiExport::set_all_dependencies_are_recorded(true);
3813 }
3814 }
3815
compute_added_deleted_matching_methods()3816 void VM_RedefineClasses::compute_added_deleted_matching_methods() {
3817 Method* old_method;
3818 Method* new_method;
3819
3820 _matching_old_methods = NEW_RESOURCE_ARRAY(Method*, _old_methods->length());
3821 _matching_new_methods = NEW_RESOURCE_ARRAY(Method*, _old_methods->length());
3822 _added_methods = NEW_RESOURCE_ARRAY(Method*, _new_methods->length());
3823 _deleted_methods = NEW_RESOURCE_ARRAY(Method*, _old_methods->length());
3824
3825 _matching_methods_length = 0;
3826 _deleted_methods_length = 0;
3827 _added_methods_length = 0;
3828
3829 int nj = 0;
3830 int oj = 0;
3831 while (true) {
3832 if (oj >= _old_methods->length()) {
3833 if (nj >= _new_methods->length()) {
3834 break; // we've looked at everything, done
3835 }
3836 // New method at the end
3837 new_method = _new_methods->at(nj);
3838 _added_methods[_added_methods_length++] = new_method;
3839 ++nj;
3840 } else if (nj >= _new_methods->length()) {
3841 // Old method, at the end, is deleted
3842 old_method = _old_methods->at(oj);
3843 _deleted_methods[_deleted_methods_length++] = old_method;
3844 ++oj;
3845 } else {
3846 old_method = _old_methods->at(oj);
3847 new_method = _new_methods->at(nj);
3848 if (old_method->name() == new_method->name()) {
3849 if (old_method->signature() == new_method->signature()) {
3850 _matching_old_methods[_matching_methods_length ] = old_method;
3851 _matching_new_methods[_matching_methods_length++] = new_method;
3852 ++nj;
3853 ++oj;
3854 } else {
3855 // added overloaded have already been moved to the end,
3856 // so this is a deleted overloaded method
3857 _deleted_methods[_deleted_methods_length++] = old_method;
3858 ++oj;
3859 }
3860 } else { // names don't match
3861 if (old_method->name()->fast_compare(new_method->name()) > 0) {
3862 // new method
3863 _added_methods[_added_methods_length++] = new_method;
3864 ++nj;
3865 } else {
3866 // deleted method
3867 _deleted_methods[_deleted_methods_length++] = old_method;
3868 ++oj;
3869 }
3870 }
3871 }
3872 }
3873 assert(_matching_methods_length + _deleted_methods_length == _old_methods->length(), "sanity");
3874 assert(_matching_methods_length + _added_methods_length == _new_methods->length(), "sanity");
3875 }
3876
3877
swap_annotations(instanceKlassHandle the_class,instanceKlassHandle scratch_class)3878 void VM_RedefineClasses::swap_annotations(instanceKlassHandle the_class,
3879 instanceKlassHandle scratch_class) {
3880 // Swap annotation fields values
3881 Annotations* old_annotations = the_class->annotations();
3882 the_class->set_annotations(scratch_class->annotations());
3883 scratch_class->set_annotations(old_annotations);
3884 }
3885
3886
3887 // Install the redefinition of a class:
3888 // - house keeping (flushing breakpoints and caches, deoptimizing
3889 // dependent compiled code)
3890 // - replacing parts in the_class with parts from scratch_class
3891 // - adding a weak reference to track the obsolete but interesting
3892 // parts of the_class
3893 // - adjusting constant pool caches and vtables in other classes
3894 // that refer to methods in the_class. These adjustments use the
3895 // ClassLoaderDataGraph::classes_do() facility which only allows
3896 // a helper method to be specified. The interesting parameters
3897 // that we would like to pass to the helper method are saved in
3898 // static global fields in the VM operation.
redefine_single_class(jclass the_jclass,Klass * scratch_class_oop,TRAPS)3899 void VM_RedefineClasses::redefine_single_class(jclass the_jclass,
3900 Klass* scratch_class_oop, TRAPS) {
3901
3902 HandleMark hm(THREAD); // make sure handles from this call are freed
3903 RC_TIMER_START(_timer_rsc_phase1);
3904
3905 instanceKlassHandle scratch_class(THREAD, scratch_class_oop);
3906 instanceKlassHandle the_class(THREAD, get_ik(the_jclass));
3907
3908 // Remove all breakpoints in methods of this class
3909 JvmtiBreakpoints& jvmti_breakpoints = JvmtiCurrentBreakpoints::get_jvmti_breakpoints();
3910 jvmti_breakpoints.clearall_in_class_at_safepoint(the_class());
3911
3912 // Deoptimize all compiled code that depends on this class
3913 flush_dependent_code(the_class, THREAD);
3914
3915 _old_methods = the_class->methods();
3916 _new_methods = scratch_class->methods();
3917 _the_class_oop = the_class();
3918 compute_added_deleted_matching_methods();
3919 update_jmethod_ids();
3920
3921 // Attach new constant pool to the original klass. The original
3922 // klass still refers to the old constant pool (for now).
3923 scratch_class->constants()->set_pool_holder(the_class());
3924
3925 #if 0
3926 // In theory, with constant pool merging in place we should be able
3927 // to save space by using the new, merged constant pool in place of
3928 // the old constant pool(s). By "pool(s)" I mean the constant pool in
3929 // the klass version we are replacing now and any constant pool(s) in
3930 // previous versions of klass. Nice theory, doesn't work in practice.
3931 // When this code is enabled, even simple programs throw NullPointer
3932 // exceptions. I'm guessing that this is caused by some constant pool
3933 // cache difference between the new, merged constant pool and the
3934 // constant pool that was just being used by the klass. I'm keeping
3935 // this code around to archive the idea, but the code has to remain
3936 // disabled for now.
3937
3938 // Attach each old method to the new constant pool. This can be
3939 // done here since we are past the bytecode verification and
3940 // constant pool optimization phases.
3941 for (int i = _old_methods->length() - 1; i >= 0; i--) {
3942 Method* method = _old_methods->at(i);
3943 method->set_constants(scratch_class->constants());
3944 }
3945
3946 {
3947 // walk all previous versions of the klass
3948 InstanceKlass *ik = (InstanceKlass *)the_class();
3949 PreviousVersionWalker pvw(ik);
3950 instanceKlassHandle ikh;
3951 do {
3952 ikh = pvw.next_previous_version();
3953 if (!ikh.is_null()) {
3954 ik = ikh();
3955
3956 // attach previous version of klass to the new constant pool
3957 ik->set_constants(scratch_class->constants());
3958
3959 // Attach each method in the previous version of klass to the
3960 // new constant pool
3961 Array<Method*>* prev_methods = ik->methods();
3962 for (int i = prev_methods->length() - 1; i >= 0; i--) {
3963 Method* method = prev_methods->at(i);
3964 method->set_constants(scratch_class->constants());
3965 }
3966 }
3967 } while (!ikh.is_null());
3968 }
3969 #endif
3970
3971 // Replace methods and constantpool
3972 the_class->set_methods(_new_methods);
3973 scratch_class->set_methods(_old_methods); // To prevent potential GCing of the old methods,
3974 // and to be able to undo operation easily.
3975
3976 Array<int>* old_ordering = the_class->method_ordering();
3977 the_class->set_method_ordering(scratch_class->method_ordering());
3978 scratch_class->set_method_ordering(old_ordering);
3979
3980 ConstantPool* old_constants = the_class->constants();
3981 the_class->set_constants(scratch_class->constants());
3982 scratch_class->set_constants(old_constants); // See the previous comment.
3983 #if 0
3984 // We are swapping the guts of "the new class" with the guts of "the
3985 // class". Since the old constant pool has just been attached to "the
3986 // new class", it seems logical to set the pool holder in the old
3987 // constant pool also. However, doing this will change the observable
3988 // class hierarchy for any old methods that are still executing. A
3989 // method can query the identity of its "holder" and this query uses
3990 // the method's constant pool link to find the holder. The change in
3991 // holding class from "the class" to "the new class" can confuse
3992 // things.
3993 //
3994 // Setting the old constant pool's holder will also cause
3995 // verification done during vtable initialization below to fail.
3996 // During vtable initialization, the vtable's class is verified to be
3997 // a subtype of the method's holder. The vtable's class is "the
3998 // class" and the method's holder is gotten from the constant pool
3999 // link in the method itself. For "the class"'s directly implemented
4000 // methods, the method holder is "the class" itself (as gotten from
4001 // the new constant pool). The check works fine in this case. The
4002 // check also works fine for methods inherited from super classes.
4003 //
4004 // Miranda methods are a little more complicated. A miranda method is
4005 // provided by an interface when the class implementing the interface
4006 // does not provide its own method. These interfaces are implemented
4007 // internally as an InstanceKlass. These special instanceKlasses
4008 // share the constant pool of the class that "implements" the
4009 // interface. By sharing the constant pool, the method holder of a
4010 // miranda method is the class that "implements" the interface. In a
4011 // non-redefine situation, the subtype check works fine. However, if
4012 // the old constant pool's pool holder is modified, then the check
4013 // fails because there is no class hierarchy relationship between the
4014 // vtable's class and "the new class".
4015
4016 old_constants->set_pool_holder(scratch_class());
4017 #endif
4018
4019 // track number of methods that are EMCP for add_previous_version() call below
4020 int emcp_method_count = check_methods_and_mark_as_obsolete();
4021 transfer_old_native_function_registrations(the_class);
4022
4023 // The class file bytes from before any retransformable agents mucked
4024 // with them was cached on the scratch class, move to the_class.
4025 // Note: we still want to do this if nothing needed caching since it
4026 // should get cleared in the_class too.
4027 if (the_class->get_cached_class_file() == 0) {
4028 // the_class doesn't have a cache yet so copy it
4029 the_class->set_cached_class_file(scratch_class->get_cached_class_file());
4030 }
4031 else if (scratch_class->get_cached_class_file() !=
4032 the_class->get_cached_class_file()) {
4033 // The same class can be present twice in the scratch classes list or there
4034 // are multiple concurrent RetransformClasses calls on different threads.
4035 // In such cases we have to deallocate scratch_class cached_class_file.
4036 os::free(scratch_class->get_cached_class_file());
4037 }
4038
4039 // NULL out in scratch class to not delete twice. The class to be redefined
4040 // always owns these bytes.
4041 scratch_class->set_cached_class_file(NULL);
4042
4043 // Replace inner_classes
4044 Array<u2>* old_inner_classes = the_class->inner_classes();
4045 the_class->set_inner_classes(scratch_class->inner_classes());
4046 scratch_class->set_inner_classes(old_inner_classes);
4047
4048 // Initialize the vtable and interface table after
4049 // methods have been rewritten
4050 {
4051 ResourceMark rm(THREAD);
4052 // no exception should happen here since we explicitly
4053 // do not check loader constraints.
4054 // compare_and_normalize_class_versions has already checked:
4055 // - classloaders unchanged, signatures unchanged
4056 // - all instanceKlasses for redefined classes reused & contents updated
4057 the_class->vtable()->initialize_vtable(false, THREAD);
4058 the_class->itable()->initialize_itable(false, THREAD);
4059 assert(!HAS_PENDING_EXCEPTION || (THREAD->pending_exception()->is_a(SystemDictionary::ThreadDeath_klass())), "redefine exception");
4060 }
4061
4062 // Leave arrays of jmethodIDs and itable index cache unchanged
4063
4064 // Copy the "source file name" attribute from new class version
4065 the_class->set_source_file_name_index(
4066 scratch_class->source_file_name_index());
4067
4068 // Copy the "source debug extension" attribute from new class version
4069 the_class->set_source_debug_extension(
4070 scratch_class->source_debug_extension(),
4071 scratch_class->source_debug_extension() == NULL ? 0 :
4072 (int)strlen(scratch_class->source_debug_extension()));
4073
4074 // Use of javac -g could be different in the old and the new
4075 if (scratch_class->access_flags().has_localvariable_table() !=
4076 the_class->access_flags().has_localvariable_table()) {
4077
4078 AccessFlags flags = the_class->access_flags();
4079 if (scratch_class->access_flags().has_localvariable_table()) {
4080 flags.set_has_localvariable_table();
4081 } else {
4082 flags.clear_has_localvariable_table();
4083 }
4084 the_class->set_access_flags(flags);
4085 }
4086
4087 swap_annotations(the_class, scratch_class);
4088
4089 // Replace minor version number of class file
4090 u2 old_minor_version = the_class->minor_version();
4091 the_class->set_minor_version(scratch_class->minor_version());
4092 scratch_class->set_minor_version(old_minor_version);
4093
4094 // Replace major version number of class file
4095 u2 old_major_version = the_class->major_version();
4096 the_class->set_major_version(scratch_class->major_version());
4097 scratch_class->set_major_version(old_major_version);
4098
4099 // Replace CP indexes for class and name+type of enclosing method
4100 u2 old_class_idx = the_class->enclosing_method_class_index();
4101 u2 old_method_idx = the_class->enclosing_method_method_index();
4102 the_class->set_enclosing_method_indices(
4103 scratch_class->enclosing_method_class_index(),
4104 scratch_class->enclosing_method_method_index());
4105 scratch_class->set_enclosing_method_indices(old_class_idx, old_method_idx);
4106
4107 the_class->set_has_been_redefined();
4108
4109 // keep track of previous versions of this class
4110 the_class->add_previous_version(scratch_class, emcp_method_count);
4111
4112 RC_TIMER_STOP(_timer_rsc_phase1);
4113 RC_TIMER_START(_timer_rsc_phase2);
4114
4115 // Adjust constantpool caches and vtables for all classes
4116 // that reference methods of the evolved class.
4117 AdjustCpoolCacheAndVtable adjust_cpool_cache_and_vtable(THREAD);
4118 ClassLoaderDataGraph::classes_do(&adjust_cpool_cache_and_vtable);
4119
4120 // JSR-292 support
4121 MemberNameTable* mnt = the_class->member_names();
4122 if (mnt != NULL) {
4123 bool trace_name_printed = false;
4124 mnt->adjust_method_entries(the_class(), &trace_name_printed);
4125 }
4126
4127 if (the_class->oop_map_cache() != NULL) {
4128 // Flush references to any obsolete methods from the oop map cache
4129 // so that obsolete methods are not pinned.
4130 the_class->oop_map_cache()->flush_obsolete_entries();
4131 }
4132
4133 // increment the classRedefinedCount field in the_class and in any
4134 // direct and indirect subclasses of the_class
4135 increment_class_counter((InstanceKlass *)the_class(), THREAD);
4136
4137 // RC_TRACE macro has an embedded ResourceMark
4138 RC_TRACE_WITH_THREAD(0x00000001, THREAD,
4139 ("redefined name=%s, count=%d (avail_mem=" UINT64_FORMAT "K)",
4140 the_class->external_name(),
4141 java_lang_Class::classRedefinedCount(the_class->java_mirror()),
4142 os::available_memory() >> 10));
4143
4144 {
4145 ResourceMark rm(THREAD);
4146 Events::log_redefinition(THREAD, "redefined class name=%s, count=%d",
4147 the_class->external_name(),
4148 java_lang_Class::classRedefinedCount(the_class->java_mirror()));
4149
4150 }
4151 RC_TIMER_STOP(_timer_rsc_phase2);
4152 } // end redefine_single_class()
4153
4154
4155 // Increment the classRedefinedCount field in the specific InstanceKlass
4156 // and in all direct and indirect subclasses.
increment_class_counter(InstanceKlass * ik,TRAPS)4157 void VM_RedefineClasses::increment_class_counter(InstanceKlass *ik, TRAPS) {
4158 oop class_mirror = ik->java_mirror();
4159 Klass* class_oop = java_lang_Class::as_Klass(class_mirror);
4160 int new_count = java_lang_Class::classRedefinedCount(class_mirror) + 1;
4161 java_lang_Class::set_classRedefinedCount(class_mirror, new_count);
4162
4163 if (class_oop != _the_class_oop) {
4164 // _the_class_oop count is printed at end of redefine_single_class()
4165 RC_TRACE_WITH_THREAD(0x00000008, THREAD,
4166 ("updated count in subclass=%s to %d", ik->external_name(), new_count));
4167 }
4168
4169 for (Klass *subk = ik->subklass(); subk != NULL;
4170 subk = subk->next_sibling()) {
4171 if (subk->oop_is_instance()) {
4172 // Only update instanceKlasses
4173 InstanceKlass *subik = (InstanceKlass*)subk;
4174 // recursively do subclasses of the current subclass
4175 increment_class_counter(subik, THREAD);
4176 }
4177 }
4178 }
4179
do_klass(Klass * k)4180 void VM_RedefineClasses::CheckClass::do_klass(Klass* k) {
4181 bool no_old_methods = true; // be optimistic
4182
4183 // Both array and instance classes have vtables.
4184 // a vtable should never contain old or obsolete methods
4185 ResourceMark rm(_thread);
4186 if (k->vtable_length() > 0 &&
4187 !k->vtable()->check_no_old_or_obsolete_entries()) {
4188 if (RC_TRACE_ENABLED(0x00004000)) {
4189 RC_TRACE_WITH_THREAD(0x00004000, _thread,
4190 ("klassVtable::check_no_old_or_obsolete_entries failure"
4191 " -- OLD or OBSOLETE method found -- class: %s",
4192 k->signature_name()));
4193 k->vtable()->dump_vtable();
4194 }
4195 no_old_methods = false;
4196 }
4197
4198 if (k->oop_is_instance()) {
4199 HandleMark hm(_thread);
4200 InstanceKlass *ik = InstanceKlass::cast(k);
4201
4202 // an itable should never contain old or obsolete methods
4203 if (ik->itable_length() > 0 &&
4204 !ik->itable()->check_no_old_or_obsolete_entries()) {
4205 if (RC_TRACE_ENABLED(0x00004000)) {
4206 RC_TRACE_WITH_THREAD(0x00004000, _thread,
4207 ("klassItable::check_no_old_or_obsolete_entries failure"
4208 " -- OLD or OBSOLETE method found -- class: %s",
4209 ik->signature_name()));
4210 ik->itable()->dump_itable();
4211 }
4212 no_old_methods = false;
4213 }
4214
4215 // the constant pool cache should never contain non-deleted old or obsolete methods
4216 if (ik->constants() != NULL &&
4217 ik->constants()->cache() != NULL &&
4218 !ik->constants()->cache()->check_no_old_or_obsolete_entries()) {
4219 if (RC_TRACE_ENABLED(0x00004000)) {
4220 RC_TRACE_WITH_THREAD(0x00004000, _thread,
4221 ("cp-cache::check_no_old_or_obsolete_entries failure"
4222 " -- OLD or OBSOLETE method found -- class: %s",
4223 ik->signature_name()));
4224 ik->constants()->cache()->dump_cache();
4225 }
4226 no_old_methods = false;
4227 }
4228 }
4229
4230 // print and fail guarantee if old methods are found.
4231 if (!no_old_methods) {
4232 if (RC_TRACE_ENABLED(0x00004000)) {
4233 dump_methods();
4234 } else {
4235 tty->print_cr("INFO: use the '-XX:TraceRedefineClasses=16384' option "
4236 "to see more info about the following guarantee() failure.");
4237 }
4238 guarantee(false, "OLD and/or OBSOLETE method(s) found");
4239 }
4240 }
4241
4242
dump_methods()4243 void VM_RedefineClasses::dump_methods() {
4244 int j;
4245 RC_TRACE(0x00004000, ("_old_methods --"));
4246 for (j = 0; j < _old_methods->length(); ++j) {
4247 Method* m = _old_methods->at(j);
4248 RC_TRACE_NO_CR(0x00004000, ("%4d (%5d) ", j, m->vtable_index()));
4249 m->access_flags().print_on(tty);
4250 tty->print(" -- ");
4251 m->print_name(tty);
4252 tty->cr();
4253 }
4254 RC_TRACE(0x00004000, ("_new_methods --"));
4255 for (j = 0; j < _new_methods->length(); ++j) {
4256 Method* m = _new_methods->at(j);
4257 RC_TRACE_NO_CR(0x00004000, ("%4d (%5d) ", j, m->vtable_index()));
4258 m->access_flags().print_on(tty);
4259 tty->print(" -- ");
4260 m->print_name(tty);
4261 tty->cr();
4262 }
4263 RC_TRACE(0x00004000, ("_matching_(old/new)_methods --"));
4264 for (j = 0; j < _matching_methods_length; ++j) {
4265 Method* m = _matching_old_methods[j];
4266 RC_TRACE_NO_CR(0x00004000, ("%4d (%5d) ", j, m->vtable_index()));
4267 m->access_flags().print_on(tty);
4268 tty->print(" -- ");
4269 m->print_name(tty);
4270 tty->cr();
4271 m = _matching_new_methods[j];
4272 RC_TRACE_NO_CR(0x00004000, (" (%5d) ", m->vtable_index()));
4273 m->access_flags().print_on(tty);
4274 tty->cr();
4275 }
4276 RC_TRACE(0x00004000, ("_deleted_methods --"));
4277 for (j = 0; j < _deleted_methods_length; ++j) {
4278 Method* m = _deleted_methods[j];
4279 RC_TRACE_NO_CR(0x00004000, ("%4d (%5d) ", j, m->vtable_index()));
4280 m->access_flags().print_on(tty);
4281 tty->print(" -- ");
4282 m->print_name(tty);
4283 tty->cr();
4284 }
4285 RC_TRACE(0x00004000, ("_added_methods --"));
4286 for (j = 0; j < _added_methods_length; ++j) {
4287 Method* m = _added_methods[j];
4288 RC_TRACE_NO_CR(0x00004000, ("%4d (%5d) ", j, m->vtable_index()));
4289 m->access_flags().print_on(tty);
4290 tty->print(" -- ");
4291 m->print_name(tty);
4292 tty->cr();
4293 }
4294 }
4295
print_on_error(outputStream * st) const4296 void VM_RedefineClasses::print_on_error(outputStream* st) const {
4297 VM_Operation::print_on_error(st);
4298 if (_the_class_oop != NULL) {
4299 ResourceMark rm;
4300 st->print_cr(", redefining class %s", _the_class_oop->external_name());
4301 }
4302 }
4303