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