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