1 /*
2 * Copyright (c) 2016, 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/classLoaderData.hpp"
27 #include "classfile/javaClasses.hpp"
28 #include "classfile/moduleEntry.hpp"
29 #include "logging/log.hpp"
30 #include "memory/resourceArea.hpp"
31 #include "oops/symbol.hpp"
32 #include "prims/jni.h"
33 #include "runtime/handles.inline.hpp"
34 #include "runtime/safepoint.hpp"
35 #include "trace/traceMacros.hpp"
36 #include "utilities/events.hpp"
37 #include "utilities/growableArray.hpp"
38 #include "utilities/hashtable.inline.hpp"
39 #include "utilities/ostream.hpp"
40
41 ModuleEntry* ModuleEntryTable::_javabase_module = NULL;
42
43 void ModuleEntry::set_location(Symbol* location) {
44 if (_location != NULL) {
45 // _location symbol's refcounts are managed by ModuleEntry,
46 // must decrement the old one before updating.
47 _location->decrement_refcount();
48 }
49
50 _location = location;
51
52 if (location != NULL) {
53 location->increment_refcount();
54 }
55 }
56
57 bool ModuleEntry::is_non_jdk_module() {
58 ResourceMark rm;
59 if (location() != NULL) {
60 const char* loc = location()->as_C_string();
61 if (strncmp(loc, "jrt:/java.", 10) != 0 && strncmp(loc, "jrt:/jdk.", 9) != 0) {
62 return true;
63 }
64 }
65 return false;
66 }
67
68 void ModuleEntry::set_version(Symbol* version) {
69 if (_version != NULL) {
70 // _version symbol's refcounts are managed by ModuleEntry,
71 // must decrement the old one before updating.
72 _version->decrement_refcount();
73 }
74
75 _version = version;
76
77 if (version != NULL) {
78 version->increment_refcount();
79 }
80 }
81
82 // Returns the shared ProtectionDomain
83 Handle ModuleEntry::shared_protection_domain() {
84 return Handle(Thread::current(), JNIHandles::resolve(_pd));
85 }
86
87 // Set the shared ProtectionDomain atomically
88 void ModuleEntry::set_shared_protection_domain(ClassLoaderData *loader_data,
89 Handle pd_h) {
90 // Create a handle for the shared ProtectionDomain and save it atomically.
91 // If someone beats us setting the _pd cache, the created handle is destroyed.
92 jobject obj = loader_data->add_handle(pd_h);
93 if (Atomic::cmpxchg_ptr(obj, &_pd, NULL) != NULL) {
94 loader_data->remove_handle_unsafe(obj);
95 }
96 }
97
98 // Returns true if this module can read module m
99 bool ModuleEntry::can_read(ModuleEntry* m) const {
100 assert(m != NULL, "No module to lookup in this module's reads list");
101
102 // Unnamed modules read everyone and all modules
103 // read java.base. If either of these conditions
104 // hold, readability has been established.
105 if (!this->is_named() ||
106 (m == ModuleEntryTable::javabase_moduleEntry())) {
107 return true;
108 }
109
110 MutexLocker m1(Module_lock);
111 // This is a guard against possible race between agent threads that redefine
112 // or retransform classes in this module. Only one of them is adding the
113 // default read edges to the unnamed modules of the boot and app class loaders
114 // with an upcall to jdk.internal.module.Modules.transformedByAgent.
115 // At the same time, another thread can instrument the module classes by
116 // injecting dependencies that require the default read edges for resolution.
117 if (this->has_default_read_edges() && !m->is_named()) {
118 ClassLoaderData* cld = m->loader_data();
119 if (cld->is_the_null_class_loader_data() || cld->is_system_class_loader_data()) {
120 return true; // default read edge
121 }
122 }
123 if (!has_reads_list()) {
124 return false;
125 } else {
126 return _reads->contains(m);
127 }
128 }
129
130 // Add a new module to this module's reads list
131 void ModuleEntry::add_read(ModuleEntry* m) {
132 // Unnamed module is special cased and can read all modules
133 if (!is_named()) {
134 return;
135 }
136
137 MutexLocker m1(Module_lock);
138 if (m == NULL) {
139 set_can_read_all_unnamed();
140 } else {
141 if (_reads == NULL) {
142 // Lazily create a module's reads list
143 _reads = new (ResourceObj::C_HEAP, mtModule)GrowableArray<ModuleEntry*>(MODULE_READS_SIZE, true);
144 }
145
146 // Determine, based on this newly established read edge to module m,
147 // if this module's read list should be walked at a GC safepoint.
148 set_read_walk_required(m->loader_data());
149
150 // Establish readability to module m
151 _reads->append_if_missing(m);
152 }
153 }
154
155 // If the module's loader, that a read edge is being established to, is
156 // not the same loader as this module's and is not one of the 3 builtin
157 // class loaders, then this module's reads list must be walked at GC
158 // safepoint. Modules have the same life cycle as their defining class
159 // loaders and should be removed if dead.
160 void ModuleEntry::set_read_walk_required(ClassLoaderData* m_loader_data) {
161 assert(is_named(), "Cannot call set_read_walk_required on unnamed module");
162 assert_locked_or_safepoint(Module_lock);
163 if (!_must_walk_reads &&
164 loader_data() != m_loader_data &&
165 !m_loader_data->is_builtin_class_loader_data()) {
166 _must_walk_reads = true;
167 if (log_is_enabled(Trace, modules)) {
168 ResourceMark rm;
169 log_trace(modules)("ModuleEntry::set_read_walk_required(): module %s reads list must be walked",
170 (name() != NULL) ? name()->as_C_string() : UNNAMED_MODULE);
171 }
172 }
173 }
174
175 // Set whether the module is open, i.e. all its packages are unqualifiedly exported
176 void ModuleEntry::set_is_open(bool is_open) {
177 assert_lock_strong(Module_lock);
178 _is_open = is_open;
179 }
180
181 // Returns true if the module has a non-empty reads list. As such, the unnamed
182 // module will return false.
183 bool ModuleEntry::has_reads_list() const {
184 assert_locked_or_safepoint(Module_lock);
185 return ((_reads != NULL) && !_reads->is_empty());
186 }
187
188 // Purge dead module entries out of reads list.
189 void ModuleEntry::purge_reads() {
190 assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint");
191
192 if (_must_walk_reads && has_reads_list()) {
193 // This module's _must_walk_reads flag will be reset based
194 // on the remaining live modules on the reads list.
195 _must_walk_reads = false;
196
197 if (log_is_enabled(Trace, modules)) {
198 ResourceMark rm;
199 log_trace(modules)("ModuleEntry::purge_reads(): module %s reads list being walked",
200 (name() != NULL) ? name()->as_C_string() : UNNAMED_MODULE);
201 }
202
203 // Go backwards because this removes entries that are dead.
204 int len = _reads->length();
205 for (int idx = len - 1; idx >= 0; idx--) {
206 ModuleEntry* module_idx = _reads->at(idx);
207 ClassLoaderData* cld_idx = module_idx->loader_data();
208 if (cld_idx->is_unloading()) {
209 _reads->delete_at(idx);
210 } else {
211 // Update the need to walk this module's reads based on live modules
212 set_read_walk_required(cld_idx);
213 }
214 }
215 }
216 }
217
218 void ModuleEntry::module_reads_do(ModuleClosure* const f) {
219 assert_locked_or_safepoint(Module_lock);
220 assert(f != NULL, "invariant");
221
222 if (has_reads_list()) {
223 int reads_len = _reads->length();
224 for (int i = 0; i < reads_len; ++i) {
225 f->do_module(_reads->at(i));
226 }
227 }
228 }
229
230 void ModuleEntry::delete_reads() {
231 assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint");
232 delete _reads;
233 _reads = NULL;
234 }
235
236 ModuleEntry* ModuleEntry::create_unnamed_module(ClassLoaderData* cld) {
237 // The java.lang.Module for this loader's
238 // corresponding unnamed module can be found in the java.lang.ClassLoader object.
239 oop module = java_lang_ClassLoader::unnamedModule(cld->class_loader());
240 ModuleEntry* unnamed_module = new_unnamed_module_entry(Handle(Thread::current(), module), cld);
241
242 // Store pointer to the ModuleEntry in the unnamed module's java.lang.Module
243 // object.
244 java_lang_Module::set_module_entry(module, unnamed_module);
245
246 return unnamed_module;
247 }
248
249 ModuleEntry* ModuleEntry::create_boot_unnamed_module(ClassLoaderData* cld) {
250 // For the boot loader, the java.lang.Module for the unnamed module
251 // is not known until a call to JVM_SetBootLoaderUnnamedModule is made. At
252 // this point initially create the ModuleEntry for the unnamed module.
253 ModuleEntry* unnamed_module = new_unnamed_module_entry(Handle(), cld);
254 assert(unnamed_module != NULL, "boot loader unnamed module should not be null");
255 return unnamed_module;
256 }
257
258 // When creating an unnamed module, this is called without holding the Module_lock.
259 // This is okay because the unnamed module gets created before the ClassLoaderData
260 // is available to other threads.
261 ModuleEntry* ModuleEntry::new_unnamed_module_entry(Handle module_handle, ClassLoaderData* cld) {
262 ModuleEntry* entry = (ModuleEntry*) NEW_C_HEAP_ARRAY(char, sizeof(ModuleEntry), mtModule);
263
264 // Initialize everything BasicHashtable would
265 entry->set_next(NULL);
266 entry->set_hash(0);
267 entry->set_literal(NULL);
268
269 // Initialize fields specific to a ModuleEntry
270 entry->init();
271
272 // Unnamed modules can read all other unnamed modules.
273 entry->set_can_read_all_unnamed();
274
275 if (!module_handle.is_null()) {
276 entry->set_module(cld->add_handle(module_handle));
277 }
278
279 entry->set_loader_data(cld);
280 entry->_is_open = true;
281
282 TRACE_INIT_ID(entry);
283
284 return entry;
285 }
286
287 void ModuleEntry::delete_unnamed_module() {
288 // Do not need unlink_entry() since the unnamed module is not in the hashtable
289 FREE_C_HEAP_ARRAY(char, this);
290 }
291
292 ModuleEntryTable::ModuleEntryTable(int table_size)
293 : Hashtable<Symbol*, mtModule>(table_size, sizeof(ModuleEntry))
294 {
295 }
296
297 ModuleEntryTable::~ModuleEntryTable() {
298 assert_locked_or_safepoint(Module_lock);
299
300 // Walk through all buckets and all entries in each bucket,
301 // freeing each entry.
302 for (int i = 0; i < table_size(); ++i) {
303 for (ModuleEntry* m = bucket(i); m != NULL;) {
304 ModuleEntry* to_remove = m;
305 // read next before freeing.
306 m = m->next();
307
308 ResourceMark rm;
309 log_debug(modules)("ModuleEntryTable: deleting module: %s", to_remove->name() != NULL ?
310 to_remove->name()->as_C_string() : UNNAMED_MODULE);
311
312 // Clean out the C heap allocated reads list first before freeing the entry
313 to_remove->delete_reads();
314 if (to_remove->name() != NULL) {
315 to_remove->name()->decrement_refcount();
316 }
317 if (to_remove->version() != NULL) {
318 to_remove->version()->decrement_refcount();
319 }
320 if (to_remove->location() != NULL) {
321 to_remove->location()->decrement_refcount();
322 }
323
324 // Unlink from the Hashtable prior to freeing
325 unlink_entry(to_remove);
326 FREE_C_HEAP_ARRAY(char, to_remove);
327 }
328 }
329 assert(number_of_entries() == 0, "should have removed all entries");
330 assert(new_entry_free_list() == NULL, "entry present on ModuleEntryTable's free list");
331 free_buckets();
332 }
333
334 ModuleEntry* ModuleEntryTable::new_entry(unsigned int hash, Handle module_handle,
335 bool is_open, Symbol* name,
336 Symbol* version, Symbol* location,
337 ClassLoaderData* loader_data) {
338 assert(Module_lock->owned_by_self(), "should have the Module_lock");
339 ModuleEntry* entry = (ModuleEntry*) NEW_C_HEAP_ARRAY(char, entry_size(), mtModule);
340
341 // Initialize everything BasicHashtable would
342 entry->set_next(NULL);
343 entry->set_hash(hash);
344 entry->set_literal(name);
345
346 // Initialize fields specific to a ModuleEntry
347 entry->init();
348 if (name != NULL) {
349 name->increment_refcount();
350 } else {
351 // Unnamed modules can read all other unnamed modules.
352 entry->set_can_read_all_unnamed();
353 }
354
355 if (!module_handle.is_null()) {
356 entry->set_module(loader_data->add_handle(module_handle));
357 }
358
359 entry->set_loader_data(loader_data);
360 entry->set_version(version);
361 entry->set_location(location);
362 entry->set_is_open(is_open);
363
364 if (ClassLoader::is_in_patch_mod_entries(name)) {
365 entry->set_is_patched();
366 if (log_is_enabled(Trace, modules, patch)) {
367 ResourceMark rm;
368 log_trace(modules, patch)("Marked module %s as patched from --patch-module", name->as_C_string());
369 }
370 }
371
372 TRACE_INIT_ID(entry);
373
374 return entry;
375 }
376
377 void ModuleEntryTable::add_entry(int index, ModuleEntry* new_entry) {
378 assert(Module_lock->owned_by_self(), "should have the Module_lock");
379 Hashtable<Symbol*, mtModule>::add_entry(index, (HashtableEntry<Symbol*, mtModule>*)new_entry);
380 }
381
382 ModuleEntry* ModuleEntryTable::locked_create_entry_or_null(Handle module_handle,
383 bool is_open,
384 Symbol* module_name,
385 Symbol* module_version,
386 Symbol* module_location,
387 ClassLoaderData* loader_data) {
388 assert(module_name != NULL, "ModuleEntryTable locked_create_entry_or_null should never be called for unnamed module.");
389 assert(Module_lock->owned_by_self(), "should have the Module_lock");
390 // Check if module already exists.
391 if (lookup_only(module_name) != NULL) {
392 return NULL;
393 } else {
394 ModuleEntry* entry = new_entry(compute_hash(module_name), module_handle, is_open, module_name,
395 module_version, module_location, loader_data);
396 add_entry(index_for(module_name), entry);
397 return entry;
398 }
399 }
400
401 // lookup_only by Symbol* to find a ModuleEntry.
402 ModuleEntry* ModuleEntryTable::lookup_only(Symbol* name) {
403 assert(name != NULL, "name cannot be NULL");
404 int index = index_for(name);
405 for (ModuleEntry* m = bucket(index); m != NULL; m = m->next()) {
406 if (m->name()->fast_compare(name) == 0) {
407 return m;
408 }
409 }
410 return NULL;
411 }
412
413 // Remove dead modules from all other alive modules' reads list.
414 // This should only occur at class unloading.
415 void ModuleEntryTable::purge_all_module_reads() {
416 assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint");
417 for (int i = 0; i < table_size(); i++) {
418 for (ModuleEntry* entry = bucket(i);
419 entry != NULL;
420 entry = entry->next()) {
421 entry->purge_reads();
422 }
423 }
424 }
425
426 void ModuleEntryTable::finalize_javabase(Handle module_handle, Symbol* version, Symbol* location) {
427 assert(Module_lock->owned_by_self(), "should have the Module_lock");
428 ClassLoaderData* boot_loader_data = ClassLoaderData::the_null_class_loader_data();
429 ModuleEntryTable* module_table = boot_loader_data->modules();
430
431 assert(module_table != NULL, "boot loader's ModuleEntryTable not defined");
432
433 if (module_handle.is_null()) {
434 fatal("Unable to finalize module definition for " JAVA_BASE_NAME);
435 }
436
437 // Set java.lang.Module, version and location for java.base
438 ModuleEntry* jb_module = javabase_moduleEntry();
439 assert(jb_module != NULL, JAVA_BASE_NAME " ModuleEntry not defined");
440 jb_module->set_version(version);
441 jb_module->set_location(location);
442 // Once java.base's ModuleEntry _module field is set with the known
443 // java.lang.Module, java.base is considered "defined" to the VM.
444 jb_module->set_module(boot_loader_data->add_handle(module_handle));
445
446 // Store pointer to the ModuleEntry for java.base in the java.lang.Module object.
447 java_lang_Module::set_module_entry(module_handle(), jb_module);
448 }
449
450 // Within java.lang.Class instances there is a java.lang.Module field that must
451 // be set with the defining module. During startup, prior to java.base's definition,
452 // classes needing their module field set are added to the fixup_module_list.
453 // Their module field is set once java.base's java.lang.Module is known to the VM.
454 void ModuleEntryTable::patch_javabase_entries(Handle module_handle) {
455 if (module_handle.is_null()) {
456 fatal("Unable to patch the module field of classes loaded prior to "
457 JAVA_BASE_NAME "'s definition, invalid java.lang.Module");
458 }
459
460 // Do the fixups for the basic primitive types
461 java_lang_Class::set_module(Universe::int_mirror(), module_handle());
462 java_lang_Class::set_module(Universe::float_mirror(), module_handle());
463 java_lang_Class::set_module(Universe::double_mirror(), module_handle());
464 java_lang_Class::set_module(Universe::byte_mirror(), module_handle());
465 java_lang_Class::set_module(Universe::bool_mirror(), module_handle());
466 java_lang_Class::set_module(Universe::char_mirror(), module_handle());
467 java_lang_Class::set_module(Universe::long_mirror(), module_handle());
468 java_lang_Class::set_module(Universe::short_mirror(), module_handle());
469 java_lang_Class::set_module(Universe::void_mirror(), module_handle());
470
471 // Do the fixups for classes that have already been created.
472 GrowableArray <Klass*>* list = java_lang_Class::fixup_module_field_list();
473 int list_length = list->length();
474 for (int i = 0; i < list_length; i++) {
475 Klass* k = list->at(i);
476 assert(k->is_klass(), "List should only hold classes");
477 java_lang_Class::fixup_module_field(k, module_handle);
478 k->class_loader_data()->dec_keep_alive();
479 }
480
481 delete java_lang_Class::fixup_module_field_list();
482 java_lang_Class::set_fixup_module_field_list(NULL);
483 }
484
485 void ModuleEntryTable::print(outputStream* st) {
486 st->print_cr("Module Entry Table (table_size=%d, entries=%d)",
487 table_size(), number_of_entries());
488 for (int i = 0; i < table_size(); i++) {
489 for (ModuleEntry* probe = bucket(i);
490 probe != NULL;
491 probe = probe->next()) {
492 probe->print(st);
493 }
494 }
495 }
496
497 void ModuleEntry::print(outputStream* st) {
498 ResourceMark rm;
499 st->print_cr("entry " PTR_FORMAT " name %s module " PTR_FORMAT " loader %s version %s location %s strict %s next " PTR_FORMAT,
500 p2i(this),
501 name() == NULL ? UNNAMED_MODULE : name()->as_C_string(),
502 p2i(module()),
503 loader_data()->loader_name(),
504 version() != NULL ? version()->as_C_string() : "NULL",
505 location() != NULL ? location()->as_C_string() : "NULL",
506 BOOL_TO_STR(!can_read_all_unnamed()), p2i(next()));
507 }
508
509 void ModuleEntryTable::verify() {
510 int element_count = 0;
511 for (int i = 0; i < table_size(); i++) {
512 for (ModuleEntry* probe = bucket(i);
513 probe != NULL;
514 probe = probe->next()) {
515 probe->verify();
516 element_count++;
517 }
518 }
519 guarantee(number_of_entries() == element_count,
520 "Verify of Module Entry Table failed");
521 DEBUG_ONLY(verify_lookup_length((double)number_of_entries() / table_size(), "Module Entry Table"));
522 }
523
524 void ModuleEntry::verify() {
525 guarantee(loader_data() != NULL, "A module entry must be associated with a loader.");
526 }