1 /*
2 * Copyright (c) 2018, 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/javaClasses.inline.hpp"
27 #include "classfile/vmSymbols.hpp"
28 #include "logging/log.hpp"
29 #include "logging/logMessage.hpp"
30 #include "logging/logStream.hpp"
31 #include "memory/heapShared.hpp"
32 #include "memory/iterator.inline.hpp"
33 #include "memory/metadataFactory.hpp"
34 #include "memory/metaspaceClosure.hpp"
35 #include "memory/metaspaceShared.hpp"
36 #include "memory/resourceArea.hpp"
37 #include "oops/compressedOops.inline.hpp"
38 #include "oops/oop.inline.hpp"
39
40 #if INCLUDE_CDS_JAVA_HEAP
41 KlassSubGraphInfo* HeapShared::_subgraph_info_list = NULL;
42 int HeapShared::_num_archived_subgraph_info_records = 0;
43 Array<ArchivedKlassSubGraphInfoRecord>* HeapShared::_archived_subgraph_info_records = NULL;
44
45 // Currently there is only one class mirror (ArchivedModuleGraph) with archived
46 // sub-graphs.
47 KlassSubGraphInfo* HeapShared::find_subgraph_info(Klass* k) {
48 KlassSubGraphInfo* info = _subgraph_info_list;
49 while (info != NULL) {
50 if (info->klass() == k) {
51 return info;
52 }
53 info = info->next();
54 }
55 return NULL;
56 }
57
58 // Get the subgraph_info for Klass k. A new subgraph_info is created if
59 // there is no existing one for k. The subgraph_info records the relocated
60 // Klass* of the original k.
61 KlassSubGraphInfo* HeapShared::get_subgraph_info(Klass* k) {
62 Klass* relocated_k = MetaspaceShared::get_relocated_klass(k);
63 KlassSubGraphInfo* info = find_subgraph_info(relocated_k);
64 if (info != NULL) {
65 return info;
66 }
67
68 info = new KlassSubGraphInfo(relocated_k, _subgraph_info_list);
69 _subgraph_info_list = info;
70 return info;
71 }
72
73 int HeapShared::num_of_subgraph_infos() {
74 int num = 0;
75 KlassSubGraphInfo* info = _subgraph_info_list;
76 while (info != NULL) {
77 num ++;
78 info = info->next();
79 }
80 return num;
81 }
82
83 // Add an entry field to the current KlassSubGraphInfo.
84 void KlassSubGraphInfo::add_subgraph_entry_field(int static_field_offset, oop v) {
85 assert(DumpSharedSpaces, "dump time only");
86 if (_subgraph_entry_fields == NULL) {
87 _subgraph_entry_fields =
88 new(ResourceObj::C_HEAP, mtClass) GrowableArray<juint>(10, true);
89 }
90 _subgraph_entry_fields->append((juint)static_field_offset);
91 _subgraph_entry_fields->append(CompressedOops::encode(v));
92 }
93
94 // Add the Klass* for an object in the current KlassSubGraphInfo's subgraphs.
95 // Only objects of boot classes can be included in sub-graph.
96 void KlassSubGraphInfo::add_subgraph_object_klass(Klass* orig_k, Klass *relocated_k) {
97 assert(DumpSharedSpaces, "dump time only");
98 assert(relocated_k == MetaspaceShared::get_relocated_klass(orig_k),
99 "must be the relocated Klass in the shared space");
100
101 if (_subgraph_object_klasses == NULL) {
102 _subgraph_object_klasses =
103 new(ResourceObj::C_HEAP, mtClass) GrowableArray<Klass*>(50, true);
104 }
105
106 assert(relocated_k->is_shared(), "must be a shared class");
107
108 if (_k == relocated_k) {
109 // Don't add the Klass containing the sub-graph to it's own klass
110 // initialization list.
111 return;
112 }
113
114 if (relocated_k->is_instance_klass()) {
115 assert(InstanceKlass::cast(relocated_k)->is_shared_boot_class(),
116 "must be boot class");
117 // SystemDictionary::xxx_klass() are not updated, need to check
118 // the original Klass*
119 if (orig_k == SystemDictionary::String_klass() ||
120 orig_k == SystemDictionary::Object_klass()) {
121 // Initialized early during VM initialization. No need to be added
122 // to the sub-graph object class list.
123 return;
124 }
125 } else if (relocated_k->is_objArray_klass()) {
126 Klass* abk = ObjArrayKlass::cast(relocated_k)->bottom_klass();
127 if (abk->is_instance_klass()) {
128 assert(InstanceKlass::cast(abk)->is_shared_boot_class(),
129 "must be boot class");
130 }
131 if (relocated_k == Universe::objectArrayKlassObj()) {
132 // Initialized early during Universe::genesis. No need to be added
133 // to the list.
134 return;
135 }
136 } else {
137 assert(relocated_k->is_typeArray_klass(), "must be");
138 // Primitive type arrays are created early during Universe::genesis.
139 return;
140 }
141
142 _subgraph_object_klasses->append_if_missing(relocated_k);
143 }
144
145 // Initialize an archived subgraph_info_record from the given KlassSubGraphInfo.
146 void ArchivedKlassSubGraphInfoRecord::init(KlassSubGraphInfo* info) {
147 _k = info->klass();
148 _next = NULL;
149 _entry_field_records = NULL;
150 _subgraph_klasses = NULL;
151
152 // populate the entry fields
153 GrowableArray<juint>* entry_fields = info->subgraph_entry_fields();
154 if (entry_fields != NULL) {
155 int num_entry_fields = entry_fields->length();
156 assert(num_entry_fields % 2 == 0, "sanity");
157 _entry_field_records =
158 MetaspaceShared::new_ro_array<juint>(num_entry_fields);
159 for (int i = 0 ; i < num_entry_fields; i++) {
160 _entry_field_records->at_put(i, entry_fields->at(i));
161 }
162 }
163
164 // the Klasses of the objects in the sub-graphs
165 GrowableArray<Klass*>* subgraph_klasses = info->subgraph_object_klasses();
166 if (subgraph_klasses != NULL) {
167 int num_subgraphs_klasses = subgraph_klasses->length();
168 _subgraph_klasses =
169 MetaspaceShared::new_ro_array<Klass*>(num_subgraphs_klasses);
170 for (int i = 0; i < num_subgraphs_klasses; i++) {
171 Klass* subgraph_k = subgraph_klasses->at(i);
172 if (log_is_enabled(Info, cds, heap)) {
173 ResourceMark rm;
174 log_info(cds, heap)(
175 "Archived object klass (%d): %s in %s sub-graphs",
176 i, subgraph_k->external_name(), _k->external_name());
177 }
178 _subgraph_klasses->at_put(i, subgraph_k);
179 }
180 }
181 }
182
183 // Build the records of archived subgraph infos, which include:
184 // - Entry points to all subgraphs from the containing class mirror. The entry
185 // points are static fields in the mirror. For each entry point, the field
186 // offset and value are recorded in the sub-graph info. The value are stored
187 // back to the corresponding field at runtime.
188 // - A list of klasses that need to be loaded/initialized before archived
189 // java object sub-graph can be accessed at runtime.
190 //
191 // The records are saved in the archive file and reloaded at runtime. Currently
192 // there is only one class mirror (ArchivedModuleGraph) with archived sub-graphs.
193 //
194 // Layout of the archived subgraph info records:
195 //
196 // records_size | num_records | records*
197 // ArchivedKlassSubGraphInfoRecord | entry_fields | subgraph_object_klasses
198 size_t HeapShared::build_archived_subgraph_info_records(int num_records) {
199 // remember the start address
200 char* start_p = MetaspaceShared::read_only_space_top();
201
202 // now populate the archived subgraph infos, which will be saved in the
203 // archive file
204 _archived_subgraph_info_records =
205 MetaspaceShared::new_ro_array<ArchivedKlassSubGraphInfoRecord>(num_records);
206 KlassSubGraphInfo* info = _subgraph_info_list;
207 int i = 0;
208 while (info != NULL) {
209 assert(i < _archived_subgraph_info_records->length(), "sanity");
210 ArchivedKlassSubGraphInfoRecord* record =
211 _archived_subgraph_info_records->adr_at(i);
212 record->init(info);
213 info = info->next();
214 i ++;
215 }
216
217 // _subgraph_info_list is no longer needed
218 delete _subgraph_info_list;
219 _subgraph_info_list = NULL;
220
221 char* end_p = MetaspaceShared::read_only_space_top();
222 size_t records_size = end_p - start_p;
223 return records_size;
224 }
225
226 // Write the subgraph info records in the shared _ro region
227 void HeapShared::write_archived_subgraph_infos() {
228 assert(DumpSharedSpaces, "dump time only");
229
230 Array<intptr_t>* records_header = MetaspaceShared::new_ro_array<intptr_t>(3);
231
232 _num_archived_subgraph_info_records = num_of_subgraph_infos();
233 size_t records_size = build_archived_subgraph_info_records(
234 _num_archived_subgraph_info_records);
235
236 // Now write the header information:
237 // records_size, num_records, _archived_subgraph_info_records
238 assert(records_header != NULL, "sanity");
239 intptr_t* p = (intptr_t*)(records_header->data());
240 *p = (intptr_t)records_size;
241 p ++;
242 *p = (intptr_t)_num_archived_subgraph_info_records;
243 p ++;
244 *p = (intptr_t)_archived_subgraph_info_records;
245 }
246
247 char* HeapShared::read_archived_subgraph_infos(char* buffer) {
248 Array<intptr_t>* records_header = (Array<intptr_t>*)buffer;
249 intptr_t* p = (intptr_t*)(records_header->data());
250 size_t records_size = (size_t)(*p);
251 p ++;
252 _num_archived_subgraph_info_records = *p;
253 p ++;
254 _archived_subgraph_info_records =
255 (Array<ArchivedKlassSubGraphInfoRecord>*)(*p);
256
257 buffer = (char*)_archived_subgraph_info_records + records_size;
258 return buffer;
259 }
260
261 void HeapShared::initialize_from_archived_subgraph(Klass* k) {
262 if (!MetaspaceShared::open_archive_heap_region_mapped()) {
263 return; // nothing to do
264 }
265
266 if (_num_archived_subgraph_info_records == 0) {
267 return; // no subgraph info records
268 }
269
270 // Initialize from archived data. Currently only ArchivedModuleGraph
271 // has archived object subgraphs, which is used during VM initialization
272 // time when bootstraping the system modules. No lock is needed.
273 Thread* THREAD = Thread::current();
274 for (int i = 0; i < _archived_subgraph_info_records->length(); i++) {
275 ArchivedKlassSubGraphInfoRecord* record = _archived_subgraph_info_records->adr_at(i);
276 if (record->klass() == k) {
277 int i;
278 // Found the archived subgraph info record for the requesting klass.
279 // Load/link/initialize the klasses of the objects in the subgraph.
280 // NULL class loader is used.
281 Array<Klass*>* klasses = record->subgraph_klasses();
282 if (klasses != NULL) {
283 for (i = 0; i < klasses->length(); i++) {
284 Klass* obj_k = klasses->at(i);
285 Klass* resolved_k = SystemDictionary::resolve_or_null(
286 (obj_k)->name(), THREAD);
287 if (resolved_k != obj_k) {
288 return;
289 }
290 if ((obj_k)->is_instance_klass()) {
291 InstanceKlass* ik = InstanceKlass::cast(obj_k);
292 ik->initialize(THREAD);
293 } else if ((obj_k)->is_objArray_klass()) {
294 ObjArrayKlass* oak = ObjArrayKlass::cast(obj_k);
295 oak->initialize(THREAD);
296 }
297 }
298 }
299
300 if (HAS_PENDING_EXCEPTION) {
301 CLEAR_PENDING_EXCEPTION;
302 // None of the field value will be set if there was an exception.
303 // The java code will not see any of the archived objects in the
304 // subgraphs referenced from k in this case.
305 return;
306 }
307
308 // Load the subgraph entry fields from the record and store them back to
309 // the corresponding fields within the mirror.
310 oop m = k->java_mirror();
311 Array<juint>* entry_field_records = record->entry_field_records();
312 if (entry_field_records != NULL) {
313 int efr_len = entry_field_records->length();
314 assert(efr_len % 2 == 0, "sanity");
315 for (i = 0; i < efr_len;) {
316 int field_offset = entry_field_records->at(i);
317 // The object refereced by the field becomes 'known' by GC from this
318 // point. All objects in the subgraph reachable from the object are
319 // also 'known' by GC.
320 oop v = MetaspaceShared::materialize_archived_object(
321 CompressedOops::decode(entry_field_records->at(i+1)));
322 m->obj_field_put(field_offset, v);
323 i += 2;
324 }
325 }
326
327 // Done. Java code can see the archived sub-graphs referenced from k's
328 // mirror after this point.
329 return;
330 }
331 }
332 }
333
334 class WalkOopAndArchiveClosure: public BasicOopIterateClosure {
335 int _level;
336 KlassSubGraphInfo* _subgraph_info;
337 oop _orig_referencing_obj;
338 oop _archived_referencing_obj;
339 public:
340 WalkOopAndArchiveClosure(int level, KlassSubGraphInfo* subgraph_info,
341 oop orig, oop archived) : _level(level),
342 _subgraph_info(subgraph_info),
343 _orig_referencing_obj(orig),
344 _archived_referencing_obj(archived) {}
345 void do_oop(narrowOop *p) { WalkOopAndArchiveClosure::do_oop_work(p); }
346 void do_oop( oop *p) { WalkOopAndArchiveClosure::do_oop_work(p); }
347
348 protected:
349 template <class T> void do_oop_work(T *p) {
350 oop obj = RawAccess<>::oop_load(p);
351 if (!CompressedOops::is_null(obj)) {
352 // A java.lang.Class instance can not be included in an archived
353 // object sub-graph.
354 if (java_lang_Class::is_instance(obj)) {
355 tty->print("Unknown java.lang.Class object is in the archived sub-graph\n");
356 vm_exit(1);
357 }
358
359 LogTarget(Debug, cds, heap) log;
360 LogStream ls(log);
361 outputStream* out = &ls;
362 {
363 ResourceMark rm;
364 log.print("(%d) %s <--- referenced from: %s",
365 _level, obj->klass()->external_name(),
366 CompressedOops::is_null(_orig_referencing_obj) ?
367 "" : _orig_referencing_obj->klass()->external_name());
368 obj->print_on(out);
369 }
370
371 if (MetaspaceShared::is_archive_object(obj)) {
372 // The current oop is an archived oop, nothing needs to be done
373 log.print("--- object is already archived ---");
374 return;
375 }
376
377 size_t field_delta = pointer_delta(
378 p, _orig_referencing_obj, sizeof(char));
379 T* new_p = (T*)(address(_archived_referencing_obj) + field_delta);
380 oop archived = MetaspaceShared::find_archived_heap_object(obj);
381 if (archived != NULL) {
382 // There is an archived copy existing, update reference to point
383 // to the archived copy
384 RawAccess<IS_NOT_NULL>::oop_store(new_p, archived);
385 log.print(
386 "--- found existing archived copy, store archived " PTR_FORMAT " in " PTR_FORMAT,
387 p2i(archived), p2i(new_p));
388 return;
389 }
390
391 int l = _level + 1;
392 Thread* THREAD = Thread::current();
393 // Archive the current oop before iterating through its references
394 archived = MetaspaceShared::archive_heap_object(obj, THREAD);
395 assert(MetaspaceShared::is_archive_object(archived), "must be archived");
396 log.print("=== archiving oop " PTR_FORMAT " ==> " PTR_FORMAT,
397 p2i(obj), p2i(archived));
398
399 // Following the references in the current oop and archive any
400 // encountered objects during the process
401 WalkOopAndArchiveClosure walker(l, _subgraph_info, obj, archived);
402 obj->oop_iterate(&walker);
403
404 // Update the reference in the archived copy of the referencing object
405 RawAccess<IS_NOT_NULL>::oop_store(new_p, archived);
406 log.print("=== store archived " PTR_FORMAT " in " PTR_FORMAT,
407 p2i(archived), p2i(new_p));
408
409 // Add the klass to the list of classes that need to be loaded before
410 // module system initialization
411 Klass *orig_k = obj->klass();
412 Klass *relocated_k = archived->klass();
413 _subgraph_info->add_subgraph_object_klass(orig_k, relocated_k);
414 }
415 }
416 };
417
418 //
419 // Start from the given static field in a java mirror and archive the
420 // complete sub-graph of java heap objects that are reached directly
421 // or indirectly from the starting object by following references.
422 // Currently, only ArchivedModuleGraph class instance (mirror) has archived
423 // object subgraphs. Sub-graph archiving restrictions (current):
424 //
425 // - All classes of objects in the archived sub-graph (including the
426 // entry class) must be boot class only.
427 // - No java.lang.Class instance (java mirror) can be included inside
428 // an archived sub-graph. Mirror can only be the sub-graph entry object.
429 //
430 // The Java heap object sub-graph archiving process (see
431 // WalkOopAndArchiveClosure):
432 //
433 // 1) Java object sub-graph archiving starts from a given static field
434 // within a Class instance (java mirror). If the static field is a
435 // refererence field and points to a non-null java object, proceed to
436 // the next step.
437 //
438 // 2) Archives the referenced java object. If an archived copy of the
439 // current object already exists, updates the pointer in the archived
440 // copy of the referencing object to point to the current archived object.
441 // Otherwise, proceed to the next step.
442 //
443 // 3) Follows all references within the current java object and recursively
444 // archive the sub-graph of objects starting from each reference.
445 //
446 // 4) Updates the pointer in the archived copy of referencing object to
447 // point to the current archived object.
448 //
449 // 5) The Klass of the current java object is added to the list of Klasses
450 // for loading and initialzing before any object in the archived graph can
451 // be accessed at runtime.
452 //
453 void HeapShared::archive_reachable_objects_from_static_field(Klass *k,
454 int field_offset,
455 BasicType field_type,
456 TRAPS) {
457 assert(DumpSharedSpaces, "dump time only");
458 assert(k->is_instance_klass(), "sanity");
459 assert(InstanceKlass::cast(k)->is_shared_boot_class(),
460 "must be boot class");
461
462 oop m = k->java_mirror();
463 oop archived_m = MetaspaceShared::find_archived_heap_object(m);
464 if (CompressedOops::is_null(archived_m)) {
465 return;
466 }
467
468 if (field_type == T_OBJECT) {
469 // obtain k's subGraph Info
470 KlassSubGraphInfo* subgraph_info = get_subgraph_info(k);
471
472 // get the object referenced by the field
473 oop f = m->obj_field(field_offset);
474 if (!CompressedOops::is_null(f)) {
475 LogTarget(Debug, cds, heap) log;
476 LogStream ls(log);
477 outputStream* out = &ls;
478 log.print("Start from: ");
479 f->print_on(out);
480
481 // get the archived copy of the field referenced object
482 oop af = MetaspaceShared::archive_heap_object(f, THREAD);
483 if (!MetaspaceShared::is_archive_object(f)) {
484 WalkOopAndArchiveClosure walker(1, subgraph_info, f, af);
485 f->oop_iterate(&walker);
486 }
487
488 // The field value is not preserved in the archived mirror.
489 // Record the field as a new subGraph entry point. The recorded
490 // information is restored from the archive at runtime.
491 subgraph_info->add_subgraph_entry_field(field_offset, af);
492 Klass *relocated_k = af->klass();
493 Klass *orig_k = f->klass();
494 subgraph_info->add_subgraph_object_klass(orig_k, relocated_k);
495 } else {
496 // The field contains null, we still need to record the entry point,
497 // so it can be restored at runtime.
498 subgraph_info->add_subgraph_entry_field(field_offset, NULL);
499 }
500 } else {
501 ShouldNotReachHere();
502 }
503 }
504
505 #define do_module_object_graph(archive_object_graph_do) \
506 archive_object_graph_do(SystemDictionary::ArchivedModuleGraph_klass(), jdk_internal_module_ArchivedModuleGraph::archivedSystemModules_offset(), T_OBJECT, CHECK); \
507 archive_object_graph_do(SystemDictionary::ArchivedModuleGraph_klass(), jdk_internal_module_ArchivedModuleGraph::archivedModuleFinder_offset(), T_OBJECT, CHECK); \
508 archive_object_graph_do(SystemDictionary::ArchivedModuleGraph_klass(), jdk_internal_module_ArchivedModuleGraph::archivedMainModule_offset(), T_OBJECT, CHECK); \
509 archive_object_graph_do(SystemDictionary::ArchivedModuleGraph_klass(), jdk_internal_module_ArchivedModuleGraph::archivedConfiguration_offset(), T_OBJECT, CHECK); \
510 archive_object_graph_do(SystemDictionary::ImmutableCollections_ListN_klass(), java_util_ImmutableCollections_ListN::EMPTY_LIST_offset(), T_OBJECT, CHECK); \
511 archive_object_graph_do(SystemDictionary::ImmutableCollections_MapN_klass(), java_util_ImmutableCollections_MapN::EMPTY_MAP_offset(), T_OBJECT, CHECK); \
512 archive_object_graph_do(SystemDictionary::ImmutableCollections_SetN_klass(), java_util_ImmutableCollections_SetN::EMPTY_SET_offset(), T_OBJECT, CHECK); \
513 archive_object_graph_do(SystemDictionary::Configuration_klass(), java_lang_module_Configuration::EMPTY_CONFIGURATION_offset(), T_OBJECT, CHECK)
514
515 void HeapShared::archive_module_graph_objects(Thread* THREAD) {
516 do_module_object_graph(archive_reachable_objects_from_static_field);
517 }
518 #endif // INCLUDE_CDS_JAVA_HEAP