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