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.inline.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 // Return true if the module's version should be displayed in error messages,
60 // logging, etc.
61 // Return false if the module's version is null, if it is unnamed, or if the
62 // module is not an upgradeable module.
63 // Detect if the module is not upgradeable by checking:
64 // 1. Module location is "jrt:/java." and its loader is boot or platform
65 // 2. Module location is "jrt:/jdk.", its loader is one of the builtin loaders
66 // and its version is the same as module java.base's version
67 // The above check is imprecise but should work in almost all cases.
68 bool ModuleEntry::should_show_version() {
69 if (version() == NULL || !is_named()) return false;
70
71 if (location() != NULL) {
72 ResourceMark rm;
73 const char* loc = location()->as_C_string();
74 ClassLoaderData* cld = loader_data();
75
76 if ((cld->is_the_null_class_loader_data() || cld->is_platform_class_loader_data()) &&
77 (strncmp(loc, "jrt:/java.", 10) == 0)) {
78 return false;
79 }
80 if ((ModuleEntryTable::javabase_moduleEntry()->version()->fast_compare(version()) == 0) &&
81 cld->is_permanent_class_loader_data() && (strncmp(loc, "jrt:/jdk.", 9) == 0)) {
82 return false;
83 }
84 }
85 return true;
86 }
87
88 void ModuleEntry::set_version(Symbol* version) {
89 if (_version != NULL) {
90 // _version symbol's refcounts are managed by ModuleEntry,
91 // must decrement the old one before updating.
92 _version->decrement_refcount();
93 }
94
95 _version = version;
96
97 if (version != NULL) {
98 version->increment_refcount();
99 }
100 }
101
102 // Returns the shared ProtectionDomain
103 oop ModuleEntry::shared_protection_domain() {
104 return _pd.resolve();
105 }
106
107 // Set the shared ProtectionDomain atomically
108 void ModuleEntry::set_shared_protection_domain(ClassLoaderData *loader_data,
109 Handle pd_h) {
110 // Create a handle for the shared ProtectionDomain and save it atomically.
111 // init_handle_locked checks if someone beats us setting the _pd cache.
112 loader_data->init_handle_locked(_pd, pd_h);
113 }
114
115 // Returns true if this module can read module m
116 bool ModuleEntry::can_read(ModuleEntry* m) const {
117 assert(m != NULL, "No module to lookup in this module's reads list");
118
119 // Unnamed modules read everyone and all modules
120 // read java.base. If either of these conditions
121 // hold, readability has been established.
122 if (!this->is_named() ||
123 (m == ModuleEntryTable::javabase_moduleEntry())) {
124 return true;
125 }
126
127 MutexLocker m1(Module_lock);
128 // This is a guard against possible race between agent threads that redefine
129 // or retransform classes in this module. Only one of them is adding the
130 // default read edges to the unnamed modules of the boot and app class loaders
131 // with an upcall to jdk.internal.module.Modules.transformedByAgent.
132 // At the same time, another thread can instrument the module classes by
133 // injecting dependencies that require the default read edges for resolution.
134 if (this->has_default_read_edges() && !m->is_named()) {
135 ClassLoaderData* cld = m->loader_data();
136 if (cld->is_the_null_class_loader_data() || cld->is_system_class_loader_data()) {
137 return true; // default read edge
138 }
139 }
140 if (!has_reads_list()) {
141 return false;
142 } else {
143 return _reads->contains(m);
144 }
145 }
146
147 // Add a new module to this module's reads list
148 void ModuleEntry::add_read(ModuleEntry* m) {
149 // Unnamed module is special cased and can read all modules
150 if (!is_named()) {
151 return;
152 }
153
154 MutexLocker m1(Module_lock);
155 if (m == NULL) {
156 set_can_read_all_unnamed();
157 } else {
158 if (_reads == NULL) {
159 // Lazily create a module's reads list
160 _reads = new (ResourceObj::C_HEAP, mtModule)GrowableArray<ModuleEntry*>(MODULE_READS_SIZE, true);
161 }
162
163 // Determine, based on this newly established read edge to module m,
164 // if this module's read list should be walked at a GC safepoint.
165 set_read_walk_required(m->loader_data());
166
167 // Establish readability to module m
168 _reads->append_if_missing(m);
169 }
170 }
171
172 // If the module's loader, that a read edge is being established to, is
173 // not the same loader as this module's and is not one of the 3 builtin
174 // class loaders, then this module's reads list must be walked at GC
175 // safepoint. Modules have the same life cycle as their defining class
176 // loaders and should be removed if dead.
177 void ModuleEntry::set_read_walk_required(ClassLoaderData* m_loader_data) {
178 assert(is_named(), "Cannot call set_read_walk_required on unnamed module");
179 assert_locked_or_safepoint(Module_lock);
180 if (!_must_walk_reads &&
181 loader_data() != m_loader_data &&
182 !m_loader_data->is_builtin_class_loader_data()) {
183 _must_walk_reads = true;
184 if (log_is_enabled(Trace, module)) {
185 ResourceMark rm;
186 log_trace(module)("ModuleEntry::set_read_walk_required(): module %s reads list must be walked",
187 (name() != NULL) ? name()->as_C_string() : UNNAMED_MODULE);
188 }
189 }
190 }
191
192 // Set whether the module is open, i.e. all its packages are unqualifiedly exported
193 void ModuleEntry::set_is_open(bool is_open) {
194 assert_lock_strong(Module_lock);
195 _is_open = is_open;
196 }
197
198 // Returns true if the module has a non-empty reads list. As such, the unnamed
199 // module will return false.
200 bool ModuleEntry::has_reads_list() const {
201 assert_locked_or_safepoint(Module_lock);
202 return ((_reads != NULL) && !_reads->is_empty());
203 }
204
205 // Purge dead module entries out of reads list.
206 void ModuleEntry::purge_reads() {
207 assert(UseZGC || SafepointSynchronize::is_at_safepoint(), "must be at safepoint");
208
209 if (_must_walk_reads && has_reads_list()) {
210 // This module's _must_walk_reads flag will be reset based
211 // on the remaining live modules on the reads list.
212 _must_walk_reads = false;
213
214 if (log_is_enabled(Trace, module)) {
215 ResourceMark rm;
216 log_trace(module)("ModuleEntry::purge_reads(): module %s reads list being walked",
217 (name() != NULL) ? name()->as_C_string() : UNNAMED_MODULE);
218 }
219
220 // Go backwards because this removes entries that are dead.
221 int len = _reads->length();
222 for (int idx = len - 1; idx >= 0; idx--) {
223 ModuleEntry* module_idx = _reads->at(idx);
224 ClassLoaderData* cld_idx = module_idx->loader_data();
225 if (cld_idx->is_unloading()) {
226 _reads->delete_at(idx);
227 } else {
228 // Update the need to walk this module's reads based on live modules
229 set_read_walk_required(cld_idx);
230 }
231 }
232 }
233 }
234
235 void ModuleEntry::module_reads_do(ModuleClosure* f) {
236 assert_locked_or_safepoint(Module_lock);
237 assert(f != NULL, "invariant");
238
239 if (has_reads_list()) {
240 int reads_len = _reads->length();
241 for (int i = 0; i < reads_len; ++i) {
242 f->do_module(_reads->at(i));
243 }
244 }
245 }
246
247 void ModuleEntry::delete_reads() {
248 assert(UseZGC || SafepointSynchronize::is_at_safepoint(), "must be at safepoint");
249 delete _reads;
250 _reads = NULL;
251 }
252
253 ModuleEntry* ModuleEntry::create_unnamed_module(ClassLoaderData* cld) {
254 // The java.lang.Module for this loader's
255 // corresponding unnamed module can be found in the java.lang.ClassLoader object.
256 oop module = java_lang_ClassLoader::unnamedModule(cld->class_loader());
257
258 // Ensure that the unnamed module was correctly set when the class loader was constructed.
259 // Guarantee will cause a recognizable crash if the user code has circumvented calling the ClassLoader constructor.
260 ResourceMark rm;
261 guarantee(java_lang_Module::is_instance(module),
262 "The unnamed module for ClassLoader %s, is null or not an instance of java.lang.Module. The class loader has not been initialized correctly.",
263 cld->loader_name_and_id());
264
265 ModuleEntry* unnamed_module = new_unnamed_module_entry(Handle(Thread::current(), module), cld);
266
267 // Store pointer to the ModuleEntry in the unnamed module's java.lang.Module object.
268 java_lang_Module::set_module_entry(module, unnamed_module);
269
270 return unnamed_module;
271 }
272
273 ModuleEntry* ModuleEntry::create_boot_unnamed_module(ClassLoaderData* cld) {
274 // For the boot loader, the java.lang.Module for the unnamed module
275 // is not known until a call to JVM_SetBootLoaderUnnamedModule is made. At
276 // this point initially create the ModuleEntry for the unnamed module.
277 ModuleEntry* unnamed_module = new_unnamed_module_entry(Handle(), cld);
278 assert(unnamed_module != NULL, "boot loader unnamed module should not be null");
279 return unnamed_module;
280 }
281
282 // When creating an unnamed module, this is called without holding the Module_lock.
283 // This is okay because the unnamed module gets created before the ClassLoaderData
284 // is available to other threads.
285 ModuleEntry* ModuleEntry::new_unnamed_module_entry(Handle module_handle, ClassLoaderData* cld) {
286 ModuleEntry* entry = (ModuleEntry*) NEW_C_HEAP_ARRAY(char, sizeof(ModuleEntry), mtModule);
287
288 // Initialize everything BasicHashtable would
289 entry->set_next(NULL);
290 entry->set_hash(0);
291 entry->set_literal(NULL);
292
293 // Initialize fields specific to a ModuleEntry
294 entry->init();
295
296 // Unnamed modules can read all other unnamed modules.
297 entry->set_can_read_all_unnamed();
298
299 if (!module_handle.is_null()) {
300 entry->set_module(cld->add_handle(module_handle));
301 }
302
303 entry->set_loader_data(cld);
304 entry->_is_open = true;
305
306 JFR_ONLY(INIT_ID(entry);)
307
308 return entry;
309 }
310
311 void ModuleEntry::delete_unnamed_module() {
312 // Do not need unlink_entry() since the unnamed module is not in the hashtable
313 FREE_C_HEAP_ARRAY(char, this);
314 }
315
316 ModuleEntryTable::ModuleEntryTable(int table_size)
317 : Hashtable<Symbol*, mtModule>(table_size, sizeof(ModuleEntry))
318 {
319 }
320
321 ModuleEntryTable::~ModuleEntryTable() {
322 assert_locked_or_safepoint(Module_lock);
323
324 // Walk through all buckets and all entries in each bucket,
325 // freeing each entry.
326 for (int i = 0; i < table_size(); ++i) {
327 for (ModuleEntry* m = bucket(i); m != NULL;) {
328 ModuleEntry* to_remove = m;
329 // read next before freeing.
330 m = m->next();
331
332 ResourceMark rm;
333 if (to_remove->name() != NULL) {
334 log_info(module, unload)("unloading module %s", to_remove->name()->as_C_string());
335 }
336 log_debug(module)("ModuleEntryTable: deleting module: %s", to_remove->name() != NULL ?
337 to_remove->name()->as_C_string() : UNNAMED_MODULE);
338
339 // Clean out the C heap allocated reads list first before freeing the entry
340 to_remove->delete_reads();
341 if (to_remove->name() != NULL) {
342 to_remove->name()->decrement_refcount();
343 }
344 if (to_remove->version() != NULL) {
345 to_remove->version()->decrement_refcount();
346 }
347 if (to_remove->location() != NULL) {
348 to_remove->location()->decrement_refcount();
349 }
350
351 // Unlink from the Hashtable prior to freeing
352 unlink_entry(to_remove);
353 FREE_C_HEAP_ARRAY(char, to_remove);
354 }
355 }
356 assert(number_of_entries() == 0, "should have removed all entries");
357 assert(new_entry_free_list() == NULL, "entry present on ModuleEntryTable's free list");
358 free_buckets();
359 }
360
361 ModuleEntry* ModuleEntryTable::new_entry(unsigned int hash, Handle module_handle,
362 bool is_open, Symbol* name,
363 Symbol* version, Symbol* location,
364 ClassLoaderData* loader_data) {
365 assert(Module_lock->owned_by_self(), "should have the Module_lock");
366 ModuleEntry* entry = (ModuleEntry*)Hashtable<Symbol*, mtModule>::allocate_new_entry(hash, name);
367
368 // Initialize fields specific to a ModuleEntry
369 entry->init();
370 if (name != NULL) {
371 name->increment_refcount();
372 } else {
373 // Unnamed modules can read all other unnamed modules.
374 entry->set_can_read_all_unnamed();
375 }
376
377 if (!module_handle.is_null()) {
378 entry->set_module(loader_data->add_handle(module_handle));
379 }
380
381 entry->set_loader_data(loader_data);
382 entry->set_version(version);
383 entry->set_location(location);
384 entry->set_is_open(is_open);
385
386 if (ClassLoader::is_in_patch_mod_entries(name)) {
387 entry->set_is_patched();
388 if (log_is_enabled(Trace, module, patch)) {
389 ResourceMark rm;
390 log_trace(module, patch)("Marked module %s as patched from --patch-module",
391 name != NULL ? name->as_C_string() : UNNAMED_MODULE);
392 }
393 }
394
395 JFR_ONLY(INIT_ID(entry);)
396
397 return entry;
398 }
399
400 void ModuleEntryTable::add_entry(int index, ModuleEntry* new_entry) {
401 assert(Module_lock->owned_by_self(), "should have the Module_lock");
402 Hashtable<Symbol*, mtModule>::add_entry(index, (HashtableEntry<Symbol*, mtModule>*)new_entry);
403 }
404
405 ModuleEntry* ModuleEntryTable::locked_create_entry_or_null(Handle module_handle,
406 bool is_open,
407 Symbol* module_name,
408 Symbol* module_version,
409 Symbol* module_location,
410 ClassLoaderData* loader_data) {
411 assert(module_name != NULL, "ModuleEntryTable locked_create_entry_or_null should never be called for unnamed module.");
412 assert(Module_lock->owned_by_self(), "should have the Module_lock");
413 // Check if module already exists.
414 if (lookup_only(module_name) != NULL) {
415 return NULL;
416 } else {
417 ModuleEntry* entry = new_entry(compute_hash(module_name), module_handle, is_open, module_name,
418 module_version, module_location, loader_data);
419 add_entry(index_for(module_name), entry);
420 return entry;
421 }
422 }
423
424 // lookup_only by Symbol* to find a ModuleEntry.
425 ModuleEntry* ModuleEntryTable::lookup_only(Symbol* name) {
426 assert(name != NULL, "name cannot be NULL");
427 int index = index_for(name);
428 for (ModuleEntry* m = bucket(index); m != NULL; m = m->next()) {
429 if (m->name()->fast_compare(name) == 0) {
430 return m;
431 }
432 }
433 return NULL;
434 }
435
436 // Remove dead modules from all other alive modules' reads list.
437 // This should only occur at class unloading.
438 void ModuleEntryTable::purge_all_module_reads() {
439 assert_locked_or_safepoint(Module_lock);
440 for (int i = 0; i < table_size(); i++) {
441 for (ModuleEntry* entry = bucket(i);
442 entry != NULL;
443 entry = entry->next()) {
444 entry->purge_reads();
445 }
446 }
447 }
448
449 void ModuleEntryTable::finalize_javabase(Handle module_handle, Symbol* version, Symbol* location) {
450 assert(Module_lock->owned_by_self(), "should have the Module_lock");
451 ClassLoaderData* boot_loader_data = ClassLoaderData::the_null_class_loader_data();
452 ModuleEntryTable* module_table = boot_loader_data->modules();
453
454 assert(module_table != NULL, "boot loader's ModuleEntryTable not defined");
455
456 if (module_handle.is_null()) {
457 fatal("Unable to finalize module definition for " JAVA_BASE_NAME);
458 }
459
460 // Set java.lang.Module, version and location for java.base
461 ModuleEntry* jb_module = javabase_moduleEntry();
462 assert(jb_module != NULL, JAVA_BASE_NAME " ModuleEntry not defined");
463 jb_module->set_version(version);
464 jb_module->set_location(location);
465 // Once java.base's ModuleEntry _module field is set with the known
466 // java.lang.Module, java.base is considered "defined" to the VM.
467 jb_module->set_module(boot_loader_data->add_handle(module_handle));
468
469 // Store pointer to the ModuleEntry for java.base in the java.lang.Module object.
470 java_lang_Module::set_module_entry(module_handle(), jb_module);
471 }
472
473 // Within java.lang.Class instances there is a java.lang.Module field that must
474 // be set with the defining module. During startup, prior to java.base's definition,
475 // classes needing their module field set are added to the fixup_module_list.
476 // Their module field is set once java.base's java.lang.Module is known to the VM.
477 void ModuleEntryTable::patch_javabase_entries(Handle module_handle) {
478 if (module_handle.is_null()) {
479 fatal("Unable to patch the module field of classes loaded prior to "
480 JAVA_BASE_NAME "'s definition, invalid java.lang.Module");
481 }
482
483 // Do the fixups for the basic primitive types
484 java_lang_Class::set_module(Universe::int_mirror(), module_handle());
485 java_lang_Class::set_module(Universe::float_mirror(), module_handle());
486 java_lang_Class::set_module(Universe::double_mirror(), module_handle());
487 java_lang_Class::set_module(Universe::byte_mirror(), module_handle());
488 java_lang_Class::set_module(Universe::bool_mirror(), module_handle());
489 java_lang_Class::set_module(Universe::char_mirror(), module_handle());
490 java_lang_Class::set_module(Universe::long_mirror(), module_handle());
491 java_lang_Class::set_module(Universe::short_mirror(), module_handle());
492 java_lang_Class::set_module(Universe::void_mirror(), module_handle());
493
494 // Do the fixups for classes that have already been created.
495 GrowableArray <Klass*>* list = java_lang_Class::fixup_module_field_list();
496 int list_length = list->length();
497 for (int i = 0; i < list_length; i++) {
498 Klass* k = list->at(i);
499 assert(k->is_klass(), "List should only hold classes");
500 java_lang_Class::fixup_module_field(k, module_handle);
501 k->class_loader_data()->dec_keep_alive();
502 }
503
504 delete java_lang_Class::fixup_module_field_list();
505 java_lang_Class::set_fixup_module_field_list(NULL);
506 }
507
508 void ModuleEntryTable::print(outputStream* st) {
509 st->print_cr("Module Entry Table (table_size=%d, entries=%d)",
510 table_size(), number_of_entries());
511 for (int i = 0; i < table_size(); i++) {
512 for (ModuleEntry* probe = bucket(i);
513 probe != NULL;
514 probe = probe->next()) {
515 probe->print(st);
516 }
517 }
518 }
519
520 void ModuleEntry::print(outputStream* st) {
521 ResourceMark rm;
522 st->print_cr("entry " PTR_FORMAT " name %s module " PTR_FORMAT " loader %s version %s location %s strict %s next " PTR_FORMAT,
523 p2i(this),
524 name() == NULL ? UNNAMED_MODULE : name()->as_C_string(),
525 p2i(module()),
526 loader_data()->loader_name_and_id(),
527 version() != NULL ? version()->as_C_string() : "NULL",
528 location() != NULL ? location()->as_C_string() : "NULL",
529 BOOL_TO_STR(!can_read_all_unnamed()), p2i(next()));
530 }
531
532 void ModuleEntryTable::verify() {
533 verify_table<ModuleEntry>("Module Entry Table");
534 }
535
536 void ModuleEntry::verify() {
537 guarantee(loader_data() != NULL, "A module entry must be associated with a loader.");
538 }