1 /*
2 * Copyright (c) 2016, 2020, 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/classLoader.hpp"
28 #include "classfile/classLoaderData.inline.hpp"
29 #include "classfile/javaClasses.inline.hpp"
30 #include "classfile/moduleEntry.hpp"
31 #include "logging/log.hpp"
32 #include "memory/resourceArea.hpp"
33 #include "memory/universe.hpp"
34 #include "oops/oopHandle.inline.hpp"
35 #include "oops/symbol.hpp"
36 #include "runtime/handles.inline.hpp"
37 #include "runtime/safepoint.hpp"
38 #include "utilities/events.hpp"
39 #include "utilities/growableArray.hpp"
40 #include "utilities/hashtable.inline.hpp"
41 #include "utilities/ostream.hpp"
42
43 ModuleEntry* ModuleEntryTable::_javabase_module = NULL;
44
45 oop ModuleEntry::module() const { return _module.resolve(); }
46
47 void ModuleEntry::set_location(Symbol* location) {
48 if (_location != NULL) {
49 // _location symbol's refcounts are managed by ModuleEntry,
50 // must decrement the old one before updating.
51 _location->decrement_refcount();
52 }
53
54 _location = location;
55
56 if (location != NULL) {
57 location->increment_refcount();
58 }
59 }
60
61 // Return true if the module's version should be displayed in error messages,
62 // logging, etc.
63 // Return false if the module's version is null, if it is unnamed, or if the
64 // module is not an upgradeable module.
65 // Detect if the module is not upgradeable by checking:
66 // 1. Module location is "jrt:/java." and its loader is boot or platform
67 // 2. Module location is "jrt:/jdk.", its loader is one of the builtin loaders
68 // and its version is the same as module java.base's version
69 // The above check is imprecise but should work in almost all cases.
70 bool ModuleEntry::should_show_version() {
71 if (version() == NULL || !is_named()) return false;
72
73 if (location() != NULL) {
74 ResourceMark rm;
75 const char* loc = location()->as_C_string();
76 ClassLoaderData* cld = loader_data();
77
78 assert(!cld->has_class_mirror_holder(), "module's cld should have a ClassLoader holder not a Class holder");
79 if ((cld->is_the_null_class_loader_data() || cld->is_platform_class_loader_data()) &&
80 (strncmp(loc, "jrt:/java.", 10) == 0)) {
81 return false;
82 }
83 if ((ModuleEntryTable::javabase_moduleEntry()->version()->fast_compare(version()) == 0) &&
84 cld->is_permanent_class_loader_data() && (strncmp(loc, "jrt:/jdk.", 9) == 0)) {
85 return false;
86 }
87 }
88 return true;
89 }
90
91 void ModuleEntry::set_version(Symbol* version) {
92 if (_version != NULL) {
93 // _version symbol's refcounts are managed by ModuleEntry,
94 // must decrement the old one before updating.
95 _version->decrement_refcount();
96 }
97
98 _version = version;
99
100 if (version != NULL) {
101 version->increment_refcount();
102 }
103 }
104
105 // Returns the shared ProtectionDomain
106 oop ModuleEntry::shared_protection_domain() {
107 return _pd.resolve();
108 }
109
110 // Set the shared ProtectionDomain atomically
111 void ModuleEntry::set_shared_protection_domain(ClassLoaderData *loader_data,
112 Handle pd_h) {
113 // Create a handle for the shared ProtectionDomain and save it atomically.
114 // init_handle_locked checks if someone beats us setting the _pd cache.
115 loader_data->init_handle_locked(_pd, pd_h);
116 }
117
118 // Returns true if this module can read module m
119 bool ModuleEntry::can_read(ModuleEntry* m) const {
120 assert(m != NULL, "No module to lookup in this module's reads list");
121
122 // Unnamed modules read everyone and all modules
123 // read java.base. If either of these conditions
124 // hold, readability has been established.
125 if (!this->is_named() ||
126 (m == ModuleEntryTable::javabase_moduleEntry())) {
127 return true;
128 }
129
130 MutexLocker m1(Module_lock);
131 // This is a guard against possible race between agent threads that redefine
132 // or retransform classes in this module. Only one of them is adding the
133 // default read edges to the unnamed modules of the boot and app class loaders
134 // with an upcall to jdk.internal.module.Modules.transformedByAgent.
135 // At the same time, another thread can instrument the module classes by
136 // injecting dependencies that require the default read edges for resolution.
137 if (this->has_default_read_edges() && !m->is_named()) {
138 ClassLoaderData* cld = m->loader_data();
139 assert(!cld->has_class_mirror_holder(), "module's cld should have a ClassLoader holder not a Class holder");
140 if (cld->is_the_null_class_loader_data() || cld->is_system_class_loader_data()) {
141 return true; // default read edge
142 }
143 }
144 if (!has_reads_list()) {
145 return false;
146 } else {
147 return _reads->contains(m);
148 }
149 }
150
151 // Add a new module to this module's reads list
152 void ModuleEntry::add_read(ModuleEntry* m) {
153 // Unnamed module is special cased and can read all modules
154 if (!is_named()) {
155 return;
156 }
157
158 MutexLocker m1(Module_lock);
159 if (m == NULL) {
160 set_can_read_all_unnamed();
161 } else {
162 if (_reads == NULL) {
163 // Lazily create a module's reads list
164 _reads = new (ResourceObj::C_HEAP, mtModule)GrowableArray<ModuleEntry*>(MODULE_READS_SIZE, true);
165 }
166
167 // Determine, based on this newly established read edge to module m,
168 // if this module's read list should be walked at a GC safepoint.
169 set_read_walk_required(m->loader_data());
170
171 // Establish readability to module m
172 _reads->append_if_missing(m);
173 }
174 }
175
176 // If the module's loader, that a read edge is being established to, is
177 // not the same loader as this module's and is not one of the 3 builtin
178 // class loaders, then this module's reads list must be walked at GC
179 // safepoint. Modules have the same life cycle as their defining class
180 // loaders and should be removed if dead.
181 void ModuleEntry::set_read_walk_required(ClassLoaderData* m_loader_data) {
182 assert(is_named(), "Cannot call set_read_walk_required on unnamed module");
183 assert_locked_or_safepoint(Module_lock);
184 if (!_must_walk_reads &&
185 loader_data() != m_loader_data &&
186 !m_loader_data->is_builtin_class_loader_data()) {
187 _must_walk_reads = true;
188 if (log_is_enabled(Trace, module)) {
189 ResourceMark rm;
190 log_trace(module)("ModuleEntry::set_read_walk_required(): module %s reads list must be walked",
191 (name() != NULL) ? name()->as_C_string() : UNNAMED_MODULE);
192 }
193 }
194 }
195
196 // Set whether the module is open, i.e. all its packages are unqualifiedly exported
197 void ModuleEntry::set_is_open(bool is_open) {
198 assert_lock_strong(Module_lock);
199 _is_open = is_open;
200 }
201
202 // Returns true if the module has a non-empty reads list. As such, the unnamed
203 // module will return false.
204 bool ModuleEntry::has_reads_list() const {
205 assert_locked_or_safepoint(Module_lock);
206 return ((_reads != NULL) && !_reads->is_empty());
207 }
208
209 // Purge dead module entries out of reads list.
210 void ModuleEntry::purge_reads() {
211 assert_locked_or_safepoint(Module_lock);
212
213 if (_must_walk_reads && has_reads_list()) {
214 // This module's _must_walk_reads flag will be reset based
215 // on the remaining live modules on the reads list.
216 _must_walk_reads = false;
217
218 if (log_is_enabled(Trace, module)) {
219 ResourceMark rm;
220 log_trace(module)("ModuleEntry::purge_reads(): module %s reads list being walked",
221 (name() != NULL) ? name()->as_C_string() : UNNAMED_MODULE);
222 }
223
224 // Go backwards because this removes entries that are dead.
225 int len = _reads->length();
226 for (int idx = len - 1; idx >= 0; idx--) {
227 ModuleEntry* module_idx = _reads->at(idx);
228 ClassLoaderData* cld_idx = module_idx->loader_data();
229 if (cld_idx->is_unloading()) {
230 _reads->delete_at(idx);
231 } else {
232 // Update the need to walk this module's reads based on live modules
233 set_read_walk_required(cld_idx);
234 }
235 }
236 }
237 }
238
239 void ModuleEntry::module_reads_do(ModuleClosure* f) {
240 assert_locked_or_safepoint(Module_lock);
241 assert(f != NULL, "invariant");
242
243 if (has_reads_list()) {
244 int reads_len = _reads->length();
245 for (int i = 0; i < reads_len; ++i) {
246 f->do_module(_reads->at(i));
247 }
248 }
249 }
250
251 void ModuleEntry::delete_reads() {
252 delete _reads;
253 _reads = NULL;
254 }
255
256 ModuleEntry* ModuleEntry::create_unnamed_module(ClassLoaderData* cld) {
257 // The java.lang.Module for this loader's
258 // corresponding unnamed module can be found in the java.lang.ClassLoader object.
259 oop module = java_lang_ClassLoader::unnamedModule(cld->class_loader());
260
261 // Ensure that the unnamed module was correctly set when the class loader was constructed.
262 // Guarantee will cause a recognizable crash if the user code has circumvented calling the ClassLoader constructor.
263 ResourceMark rm;
264 guarantee(java_lang_Module::is_instance(module),
265 "The unnamed module for ClassLoader %s, is null or not an instance of java.lang.Module. The class loader has not been initialized correctly.",
266 cld->loader_name_and_id());
267
268 ModuleEntry* unnamed_module = new_unnamed_module_entry(Handle(Thread::current(), module), cld);
269
270 // Store pointer to the ModuleEntry in the unnamed module's java.lang.Module object.
271 java_lang_Module::set_module_entry(module, unnamed_module);
272
273 return unnamed_module;
274 }
275
276 ModuleEntry* ModuleEntry::create_boot_unnamed_module(ClassLoaderData* cld) {
277 // For the boot loader, the java.lang.Module for the unnamed module
278 // is not known until a call to JVM_SetBootLoaderUnnamedModule is made. At
279 // this point initially create the ModuleEntry for the unnamed module.
280 ModuleEntry* unnamed_module = new_unnamed_module_entry(Handle(), cld);
281 assert(unnamed_module != NULL, "boot loader unnamed module should not be null");
282 return unnamed_module;
283 }
284
285 // When creating an unnamed module, this is called without holding the Module_lock.
286 // This is okay because the unnamed module gets created before the ClassLoaderData
287 // is available to other threads.
288 ModuleEntry* ModuleEntry::new_unnamed_module_entry(Handle module_handle, ClassLoaderData* cld) {
289 ModuleEntry* entry = NEW_C_HEAP_OBJ(ModuleEntry, mtModule);
290
291 // Initialize everything BasicHashtable would
292 entry->set_next(NULL);
293 entry->set_hash(0);
294 entry->set_literal(NULL);
295
296 // Initialize fields specific to a ModuleEntry
297 entry->init();
298
299 // Unnamed modules can read all other unnamed modules.
300 entry->set_can_read_all_unnamed();
301
302 if (!module_handle.is_null()) {
303 entry->set_module(cld->add_handle(module_handle));
304 }
305
306 entry->set_loader_data(cld);
307 entry->_is_open = true;
308
309 JFR_ONLY(INIT_ID(entry);)
310
311 return entry;
312 }
313
314 void ModuleEntry::delete_unnamed_module() {
315 // Do not need unlink_entry() since the unnamed module is not in the hashtable
316 FREE_C_HEAP_OBJ(this);
317 }
318
319 ModuleEntryTable::ModuleEntryTable(int table_size)
320 : Hashtable<Symbol*, mtModule>(table_size, sizeof(ModuleEntry))
321 {
322 }
323
324 ModuleEntryTable::~ModuleEntryTable() {
325 // Walk through all buckets and all entries in each bucket,
326 // freeing each entry.
327 for (int i = 0; i < table_size(); ++i) {
328 for (ModuleEntry* m = bucket(i); m != NULL;) {
329 ModuleEntry* to_remove = m;
330 // read next before freeing.
331 m = m->next();
332
333 ResourceMark rm;
334 if (to_remove->name() != NULL) {
335 log_info(module, unload)("unloading module %s", to_remove->name()->as_C_string());
336 }
337 log_debug(module)("ModuleEntryTable: deleting module: %s", to_remove->name() != NULL ?
338 to_remove->name()->as_C_string() : UNNAMED_MODULE);
339
340 // Clean out the C heap allocated reads list first before freeing the entry
341 to_remove->delete_reads();
342 if (to_remove->name() != NULL) {
343 to_remove->name()->decrement_refcount();
344 }
345 if (to_remove->version() != NULL) {
346 to_remove->version()->decrement_refcount();
347 }
348 if (to_remove->location() != NULL) {
349 to_remove->location()->decrement_refcount();
350 }
351
352 // Unlink from the Hashtable prior to freeing
353 unlink_entry(to_remove);
354 FREE_C_HEAP_ARRAY(char, to_remove);
355 }
356 }
357 assert(number_of_entries() == 0, "should have removed all entries");
358 assert(new_entry_free_list() == NULL, "entry present on ModuleEntryTable's free list");
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 // Create an entry in the class loader's module_entry_table. It is the
406 // caller's responsibility to ensure that the entry has not already been
407 // created.
408 ModuleEntry* ModuleEntryTable::locked_create_entry(Handle module_handle,
409 bool is_open,
410 Symbol* module_name,
411 Symbol* module_version,
412 Symbol* module_location,
413 ClassLoaderData* loader_data) {
414 assert(module_name != NULL, "ModuleEntryTable locked_create_entry should never be called for unnamed module.");
415 assert(Module_lock->owned_by_self(), "should have the Module_lock");
416 assert(lookup_only(module_name) == NULL, "Module already exists");
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 // lookup_only by Symbol* to find a ModuleEntry.
424 ModuleEntry* ModuleEntryTable::lookup_only(Symbol* name) {
425 assert(name != NULL, "name cannot be NULL");
426 int index = index_for(name);
427 for (ModuleEntry* m = bucket(index); m != NULL; m = m->next()) {
428 if (m->name()->fast_compare(name) == 0) {
429 return m;
430 }
431 }
432 return NULL;
433 }
434
435 // Remove dead modules from all other alive modules' reads list.
436 // This should only occur at class unloading.
437 void ModuleEntryTable::purge_all_module_reads() {
438 assert_locked_or_safepoint(Module_lock);
439 for (int i = 0; i < table_size(); i++) {
440 for (ModuleEntry* entry = bucket(i);
441 entry != NULL;
442 entry = entry->next()) {
443 entry->purge_reads();
444 }
445 }
446 }
447
448 void ModuleEntryTable::finalize_javabase(Handle module_handle, Symbol* version, Symbol* location) {
449 assert(Module_lock->owned_by_self(), "should have the Module_lock");
450 ClassLoaderData* boot_loader_data = ClassLoaderData::the_null_class_loader_data();
451 ModuleEntryTable* module_table = boot_loader_data->modules();
452
453 assert(module_table != NULL, "boot loader's ModuleEntryTable not defined");
454
455 if (module_handle.is_null()) {
456 fatal("Unable to finalize module definition for " JAVA_BASE_NAME);
457 }
458
459 // Set java.lang.Module, version and location for java.base
460 ModuleEntry* jb_module = javabase_moduleEntry();
461 assert(jb_module != NULL, JAVA_BASE_NAME " ModuleEntry not defined");
462 jb_module->set_version(version);
463 jb_module->set_location(location);
464 // Once java.base's ModuleEntry _module field is set with the known
465 // java.lang.Module, java.base is considered "defined" to the VM.
466 jb_module->set_module(boot_loader_data->add_handle(module_handle));
467
468 // Store pointer to the ModuleEntry for java.base in the java.lang.Module object.
469 java_lang_Module::set_module_entry(module_handle(), jb_module);
470 }
471
472 // Within java.lang.Class instances there is a java.lang.Module field that must
473 // be set with the defining module. During startup, prior to java.base's definition,
474 // classes needing their module field set are added to the fixup_module_list.
475 // Their module field is set once java.base's java.lang.Module is known to the VM.
476 void ModuleEntryTable::patch_javabase_entries(Handle module_handle) {
477 if (module_handle.is_null()) {
478 fatal("Unable to patch the module field of classes loaded prior to "
479 JAVA_BASE_NAME "'s definition, invalid java.lang.Module");
480 }
481
482 // Do the fixups for the basic primitive types
483 java_lang_Class::set_module(Universe::int_mirror(), module_handle());
484 java_lang_Class::set_module(Universe::float_mirror(), module_handle());
485 java_lang_Class::set_module(Universe::double_mirror(), module_handle());
486 java_lang_Class::set_module(Universe::byte_mirror(), module_handle());
487 java_lang_Class::set_module(Universe::bool_mirror(), module_handle());
488 java_lang_Class::set_module(Universe::char_mirror(), module_handle());
489 java_lang_Class::set_module(Universe::long_mirror(), module_handle());
490 java_lang_Class::set_module(Universe::short_mirror(), module_handle());
491 java_lang_Class::set_module(Universe::void_mirror(), module_handle());
492
493 // Do the fixups for classes that have already been created.
494 GrowableArray <Klass*>* list = java_lang_Class::fixup_module_field_list();
495 int list_length = list->length();
496 for (int i = 0; i < list_length; i++) {
497 Klass* k = list->at(i);
498 assert(k->is_klass(), "List should only hold classes");
499 java_lang_Class::fixup_module_field(k, module_handle);
500 k->class_loader_data()->dec_keep_alive();
501 }
502
503 delete java_lang_Class::fixup_module_field_list();
504 java_lang_Class::set_fixup_module_field_list(NULL);
505 }
506
507 void ModuleEntryTable::print(outputStream* st) {
508 st->print_cr("Module Entry Table (table_size=%d, entries=%d)",
509 table_size(), number_of_entries());
510 for (int i = 0; i < table_size(); i++) {
511 for (ModuleEntry* probe = bucket(i);
512 probe != NULL;
513 probe = probe->next()) {
514 probe->print(st);
515 }
516 }
517 }
518
519 void ModuleEntry::print(outputStream* st) {
520 ResourceMark rm;
521 st->print_cr("entry " PTR_FORMAT " name %s module " PTR_FORMAT " loader %s version %s location %s strict %s next " PTR_FORMAT,
522 p2i(this),
523 name() == NULL ? UNNAMED_MODULE : name()->as_C_string(),
524 p2i(module()),
525 loader_data()->loader_name_and_id(),
526 version() != NULL ? version()->as_C_string() : "NULL",
527 location() != NULL ? location()->as_C_string() : "NULL",
528 BOOL_TO_STR(!can_read_all_unnamed()), p2i(next()));
529 }
530
531 void ModuleEntryTable::verify() {
532 verify_table<ModuleEntry>("Module Entry Table");
533 }
534
535 void ModuleEntry::verify() {
536 guarantee(loader_data() != NULL, "A module entry must be associated with a loader.");
537 }