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/filemap.hpp"
33 #include "memory/resourceArea.hpp"
34 #include "memory/universe.hpp"
35 #include "oops/oopHandle.inline.hpp"
36 #include "oops/symbol.hpp"
37 #include "runtime/handles.inline.hpp"
38 #include "runtime/safepoint.hpp"
39 #include "utilities/events.hpp"
40 #include "utilities/growableArray.hpp"
41 #include "utilities/hashtable.inline.hpp"
42 #include "utilities/ostream.hpp"
43
44 ModuleEntry* ModuleEntryTable::_javabase_module = NULL;
45
46 oop ModuleEntry::module() const { return _module.resolve(); }
47
48 void ModuleEntry::set_location(Symbol* location) {
49 if (_location != NULL) {
50 // _location symbol's refcounts are managed by ModuleEntry,
51 // must decrement the old one before updating.
52 _location->decrement_refcount();
53 }
54
55 _location = location;
56
57 if (location != NULL) {
58 location->increment_refcount();
59 CDS_ONLY(if (UseSharedSpaces) {
60 _shared_path_index = FileMapInfo::get_module_shared_path_index(location);
61 });
62 }
63 }
64
65 // Return true if the module's version should be displayed in error messages,
66 // logging, etc.
67 // Return false if the module's version is null, if it is unnamed, or if the
68 // module is not an upgradeable module.
69 // Detect if the module is not upgradeable by checking:
70 // 1. Module location is "jrt:/java." and its loader is boot or platform
71 // 2. Module location is "jrt:/jdk.", its loader is one of the builtin loaders
72 // and its version is the same as module java.base's version
73 // The above check is imprecise but should work in almost all cases.
74 bool ModuleEntry::should_show_version() {
75 if (version() == NULL || !is_named()) return false;
76
77 if (location() != NULL) {
78 ResourceMark rm;
79 const char* loc = location()->as_C_string();
80 ClassLoaderData* cld = loader_data();
81
82 assert(!cld->has_class_mirror_holder(), "module's cld should have a ClassLoader holder not a Class holder");
83 if ((cld->is_the_null_class_loader_data() || cld->is_platform_class_loader_data()) &&
84 (strncmp(loc, "jrt:/java.", 10) == 0)) {
85 return false;
86 }
87 if ((ModuleEntryTable::javabase_moduleEntry()->version()->fast_compare(version()) == 0) &&
88 cld->is_permanent_class_loader_data() && (strncmp(loc, "jrt:/jdk.", 9) == 0)) {
89 return false;
90 }
91 }
92 return true;
93 }
94
95 void ModuleEntry::set_version(Symbol* version) {
96 if (_version != NULL) {
97 // _version symbol's refcounts are managed by ModuleEntry,
98 // must decrement the old one before updating.
99 _version->decrement_refcount();
100 }
101
102 _version = version;
103
104 if (version != NULL) {
105 version->increment_refcount();
106 }
107 }
108
109 // Returns the shared ProtectionDomain
110 oop ModuleEntry::shared_protection_domain() {
111 return _pd.resolve();
112 }
113
114 // Set the shared ProtectionDomain atomically
115 void ModuleEntry::set_shared_protection_domain(ClassLoaderData *loader_data,
116 Handle pd_h) {
117 // Create a handle for the shared ProtectionDomain and save it atomically.
118 // init_handle_locked checks if someone beats us setting the _pd cache.
119 loader_data->init_handle_locked(_pd, pd_h);
120 }
121
122 // Returns true if this module can read module m
123 bool ModuleEntry::can_read(ModuleEntry* m) const {
124 assert(m != NULL, "No module to lookup in this module's reads list");
125
126 // Unnamed modules read everyone and all modules
127 // read java.base. If either of these conditions
128 // hold, readability has been established.
129 if (!this->is_named() ||
130 (m == ModuleEntryTable::javabase_moduleEntry())) {
131 return true;
132 }
133
134 MutexLocker m1(Module_lock);
135 // This is a guard against possible race between agent threads that redefine
136 // or retransform classes in this module. Only one of them is adding the
137 // default read edges to the unnamed modules of the boot and app class loaders
138 // with an upcall to jdk.internal.module.Modules.transformedByAgent.
139 // At the same time, another thread can instrument the module classes by
140 // injecting dependencies that require the default read edges for resolution.
141 if (this->has_default_read_edges() && !m->is_named()) {
142 ClassLoaderData* cld = m->loader_data();
143 assert(!cld->has_class_mirror_holder(), "module's cld should have a ClassLoader holder not a Class holder");
144 if (cld->is_the_null_class_loader_data() || cld->is_system_class_loader_data()) {
145 return true; // default read edge
146 }
147 }
148 if (!has_reads_list()) {
149 return false;
150 } else {
151 return _reads->contains(m);
152 }
153 }
154
155 // Add a new module to this module's reads list
156 void ModuleEntry::add_read(ModuleEntry* m) {
157 // Unnamed module is special cased and can read all modules
158 if (!is_named()) {
159 return;
160 }
161
162 MutexLocker m1(Module_lock);
163 if (m == NULL) {
164 set_can_read_all_unnamed();
165 } else {
166 if (_reads == NULL) {
167 // Lazily create a module's reads list
168 _reads = new (ResourceObj::C_HEAP, mtModule) GrowableArray<ModuleEntry*>(MODULE_READS_SIZE, mtModule);
169 }
170
171 // Determine, based on this newly established read edge to module m,
172 // if this module's read list should be walked at a GC safepoint.
173 set_read_walk_required(m->loader_data());
174
175 // Establish readability to module m
176 _reads->append_if_missing(m);
177 }
178 }
179
180 // If the module's loader, that a read edge is being established to, is
181 // not the same loader as this module's and is not one of the 3 builtin
182 // class loaders, then this module's reads list must be walked at GC
183 // safepoint. Modules have the same life cycle as their defining class
184 // loaders and should be removed if dead.
185 void ModuleEntry::set_read_walk_required(ClassLoaderData* m_loader_data) {
186 assert(is_named(), "Cannot call set_read_walk_required on unnamed module");
187 assert_locked_or_safepoint(Module_lock);
188 if (!_must_walk_reads &&
189 loader_data() != m_loader_data &&
190 !m_loader_data->is_builtin_class_loader_data()) {
191 _must_walk_reads = true;
192 if (log_is_enabled(Trace, module)) {
193 ResourceMark rm;
194 log_trace(module)("ModuleEntry::set_read_walk_required(): module %s reads list must be walked",
195 (name() != NULL) ? name()->as_C_string() : UNNAMED_MODULE);
196 }
197 }
198 }
199
200 // Set whether the module is open, i.e. all its packages are unqualifiedly exported
201 void ModuleEntry::set_is_open(bool is_open) {
202 assert_lock_strong(Module_lock);
203 _is_open = is_open;
204 }
205
206 // Returns true if the module has a non-empty reads list. As such, the unnamed
207 // module will return false.
208 bool ModuleEntry::has_reads_list() const {
209 assert_locked_or_safepoint(Module_lock);
210 return ((_reads != NULL) && !_reads->is_empty());
211 }
212
213 // Purge dead module entries out of reads list.
214 void ModuleEntry::purge_reads() {
215 assert_locked_or_safepoint(Module_lock);
216
217 if (_must_walk_reads && has_reads_list()) {
218 // This module's _must_walk_reads flag will be reset based
219 // on the remaining live modules on the reads list.
220 _must_walk_reads = false;
221
222 if (log_is_enabled(Trace, module)) {
223 ResourceMark rm;
224 log_trace(module)("ModuleEntry::purge_reads(): module %s reads list being walked",
225 (name() != NULL) ? name()->as_C_string() : UNNAMED_MODULE);
226 }
227
228 // Go backwards because this removes entries that are dead.
229 int len = _reads->length();
230 for (int idx = len - 1; idx >= 0; idx--) {
231 ModuleEntry* module_idx = _reads->at(idx);
232 ClassLoaderData* cld_idx = module_idx->loader_data();
233 if (cld_idx->is_unloading()) {
234 _reads->delete_at(idx);
235 } else {
236 // Update the need to walk this module's reads based on live modules
237 set_read_walk_required(cld_idx);
238 }
239 }
240 }
241 }
242
243 void ModuleEntry::module_reads_do(ModuleClosure* f) {
244 assert_locked_or_safepoint(Module_lock);
245 assert(f != NULL, "invariant");
246
247 if (has_reads_list()) {
248 int reads_len = _reads->length();
249 for (int i = 0; i < reads_len; ++i) {
250 f->do_module(_reads->at(i));
251 }
252 }
253 }
254
255 void ModuleEntry::delete_reads() {
256 delete _reads;
257 _reads = NULL;
258 }
259
260 ModuleEntry* ModuleEntry::create_unnamed_module(ClassLoaderData* cld) {
261 // The java.lang.Module for this loader's
262 // corresponding unnamed module can be found in the java.lang.ClassLoader object.
263 oop module = java_lang_ClassLoader::unnamedModule(cld->class_loader());
264
265 // Ensure that the unnamed module was correctly set when the class loader was constructed.
266 // Guarantee will cause a recognizable crash if the user code has circumvented calling the ClassLoader constructor.
267 ResourceMark rm;
268 guarantee(java_lang_Module::is_instance(module),
269 "The unnamed module for ClassLoader %s, is null or not an instance of java.lang.Module. The class loader has not been initialized correctly.",
270 cld->loader_name_and_id());
271
272 ModuleEntry* unnamed_module = new_unnamed_module_entry(Handle(Thread::current(), module), cld);
273
274 // Store pointer to the ModuleEntry in the unnamed module's java.lang.Module object.
275 java_lang_Module::set_module_entry(module, unnamed_module);
276
277 return unnamed_module;
278 }
279
280 ModuleEntry* ModuleEntry::create_boot_unnamed_module(ClassLoaderData* cld) {
281 // For the boot loader, the java.lang.Module for the unnamed module
282 // is not known until a call to JVM_SetBootLoaderUnnamedModule is made. At
283 // this point initially create the ModuleEntry for the unnamed module.
284 ModuleEntry* unnamed_module = new_unnamed_module_entry(Handle(), cld);
285 assert(unnamed_module != NULL, "boot loader unnamed module should not be null");
286 return unnamed_module;
287 }
288
289 // When creating an unnamed module, this is called without holding the Module_lock.
290 // This is okay because the unnamed module gets created before the ClassLoaderData
291 // is available to other threads.
292 ModuleEntry* ModuleEntry::new_unnamed_module_entry(Handle module_handle, ClassLoaderData* cld) {
293 ModuleEntry* entry = NEW_C_HEAP_OBJ(ModuleEntry, mtModule);
294
295 // Initialize everything BasicHashtable would
296 entry->set_next(NULL);
297 entry->set_hash(0);
298 entry->set_literal(NULL);
299
300 // Initialize fields specific to a ModuleEntry
301 entry->init();
302
303 // Unnamed modules can read all other unnamed modules.
304 entry->set_can_read_all_unnamed();
305
306 if (!module_handle.is_null()) {
307 entry->set_module(cld->add_handle(module_handle));
308 }
309
310 entry->set_loader_data(cld);
311 entry->_is_open = true;
312
313 JFR_ONLY(INIT_ID(entry);)
314
315 return entry;
316 }
317
318 void ModuleEntry::delete_unnamed_module() {
319 // Do not need unlink_entry() since the unnamed module is not in the hashtable
320 FREE_C_HEAP_OBJ(this);
321 }
322
323 ModuleEntryTable::ModuleEntryTable(int table_size)
324 : Hashtable<Symbol*, mtModule>(table_size, sizeof(ModuleEntry))
325 {
326 }
327
328 ModuleEntryTable::~ModuleEntryTable() {
329 // Walk through all buckets and all entries in each bucket,
330 // freeing each entry.
331 for (int i = 0; i < table_size(); ++i) {
332 for (ModuleEntry* m = bucket(i); m != NULL;) {
333 ModuleEntry* to_remove = m;
334 // read next before freeing.
335 m = m->next();
336
337 ResourceMark rm;
338 if (to_remove->name() != NULL) {
339 log_info(module, unload)("unloading module %s", to_remove->name()->as_C_string());
340 }
341 log_debug(module)("ModuleEntryTable: deleting module: %s", to_remove->name() != NULL ?
342 to_remove->name()->as_C_string() : UNNAMED_MODULE);
343
344 // Clean out the C heap allocated reads list first before freeing the entry
345 to_remove->delete_reads();
346 if (to_remove->name() != NULL) {
347 to_remove->name()->decrement_refcount();
348 }
349 if (to_remove->version() != NULL) {
350 to_remove->version()->decrement_refcount();
351 }
352 if (to_remove->location() != NULL) {
353 to_remove->location()->decrement_refcount();
354 }
355
356 // Unlink from the Hashtable prior to freeing
357 unlink_entry(to_remove);
358 FREE_C_HEAP_ARRAY(char, to_remove);
359 }
360 }
361 assert(number_of_entries() == 0, "should have removed all entries");
362 assert(new_entry_free_list() == NULL, "entry present on ModuleEntryTable's free list");
363 }
364
365 ModuleEntry* ModuleEntryTable::new_entry(unsigned int hash, Handle module_handle,
366 bool is_open, Symbol* name,
367 Symbol* version, Symbol* location,
368 ClassLoaderData* loader_data) {
369 assert(Module_lock->owned_by_self(), "should have the Module_lock");
370 ModuleEntry* entry = (ModuleEntry*)Hashtable<Symbol*, mtModule>::allocate_new_entry(hash, name);
371
372 // Initialize fields specific to a ModuleEntry
373 entry->init();
374 if (name != NULL) {
375 name->increment_refcount();
376 } else {
377 // Unnamed modules can read all other unnamed modules.
378 entry->set_can_read_all_unnamed();
379 }
380
381 if (!module_handle.is_null()) {
382 entry->set_module(loader_data->add_handle(module_handle));
383 }
384
385 entry->set_loader_data(loader_data);
386 entry->set_version(version);
387 entry->set_location(location);
388 entry->set_is_open(is_open);
389
390 if (ClassLoader::is_in_patch_mod_entries(name)) {
391 entry->set_is_patched();
392 if (log_is_enabled(Trace, module, patch)) {
393 ResourceMark rm;
394 log_trace(module, patch)("Marked module %s as patched from --patch-module",
395 name != NULL ? name->as_C_string() : UNNAMED_MODULE);
396 }
397 }
398
399 JFR_ONLY(INIT_ID(entry);)
400
401 return entry;
402 }
403
404 void ModuleEntryTable::add_entry(int index, ModuleEntry* new_entry) {
405 assert(Module_lock->owned_by_self(), "should have the Module_lock");
406 Hashtable<Symbol*, mtModule>::add_entry(index, (HashtableEntry<Symbol*, mtModule>*)new_entry);
407 }
408
409 // Create an entry in the class loader's module_entry_table. It is the
410 // caller's responsibility to ensure that the entry has not already been
411 // created.
412 ModuleEntry* ModuleEntryTable::locked_create_entry(Handle module_handle,
413 bool is_open,
414 Symbol* module_name,
415 Symbol* module_version,
416 Symbol* module_location,
417 ClassLoaderData* loader_data) {
418 assert(module_name != NULL, "ModuleEntryTable locked_create_entry should never be called for unnamed module.");
419 assert(Module_lock->owned_by_self(), "should have the Module_lock");
420 assert(lookup_only(module_name) == NULL, "Module already exists");
421 ModuleEntry* entry = new_entry(compute_hash(module_name), module_handle, is_open, module_name,
422 module_version, module_location, loader_data);
423 add_entry(index_for(module_name), entry);
424 return entry;
425 }
426
427 // lookup_only by Symbol* to find a ModuleEntry.
428 ModuleEntry* ModuleEntryTable::lookup_only(Symbol* name) {
429 assert(name != NULL, "name cannot be NULL");
430 int index = index_for(name);
431 for (ModuleEntry* m = bucket(index); m != NULL; m = m->next()) {
432 if (m->name()->fast_compare(name) == 0) {
433 return m;
434 }
435 }
436 return NULL;
437 }
438
439 // Remove dead modules from all other alive modules' reads list.
440 // This should only occur at class unloading.
441 void ModuleEntryTable::purge_all_module_reads() {
442 assert_locked_or_safepoint(Module_lock);
443 for (int i = 0; i < table_size(); i++) {
444 for (ModuleEntry* entry = bucket(i);
445 entry != NULL;
446 entry = entry->next()) {
447 entry->purge_reads();
448 }
449 }
450 }
451
452 void ModuleEntryTable::finalize_javabase(Handle module_handle, Symbol* version, Symbol* location) {
453 assert(Module_lock->owned_by_self(), "should have the Module_lock");
454 ClassLoaderData* boot_loader_data = ClassLoaderData::the_null_class_loader_data();
455 ModuleEntryTable* module_table = boot_loader_data->modules();
456
457 assert(module_table != NULL, "boot loader's ModuleEntryTable not defined");
458
459 if (module_handle.is_null()) {
460 fatal("Unable to finalize module definition for " JAVA_BASE_NAME);
461 }
462
463 // Set java.lang.Module, version and location for java.base
464 ModuleEntry* jb_module = javabase_moduleEntry();
465 assert(jb_module != NULL, JAVA_BASE_NAME " ModuleEntry not defined");
466 jb_module->set_version(version);
467 jb_module->set_location(location);
468 // Once java.base's ModuleEntry _module field is set with the known
469 // java.lang.Module, java.base is considered "defined" to the VM.
470 jb_module->set_module(boot_loader_data->add_handle(module_handle));
471
472 // Store pointer to the ModuleEntry for java.base in the java.lang.Module object.
473 java_lang_Module::set_module_entry(module_handle(), jb_module);
474 }
475
476 // Within java.lang.Class instances there is a java.lang.Module field that must
477 // be set with the defining module. During startup, prior to java.base's definition,
478 // classes needing their module field set are added to the fixup_module_list.
479 // Their module field is set once java.base's java.lang.Module is known to the VM.
480 void ModuleEntryTable::patch_javabase_entries(Handle module_handle) {
481 if (module_handle.is_null()) {
482 fatal("Unable to patch the module field of classes loaded prior to "
483 JAVA_BASE_NAME "'s definition, invalid java.lang.Module");
484 }
485
486 // Do the fixups for the basic primitive types
487 java_lang_Class::set_module(Universe::int_mirror(), module_handle());
488 java_lang_Class::set_module(Universe::float_mirror(), module_handle());
489 java_lang_Class::set_module(Universe::double_mirror(), module_handle());
490 java_lang_Class::set_module(Universe::byte_mirror(), module_handle());
491 java_lang_Class::set_module(Universe::bool_mirror(), module_handle());
492 java_lang_Class::set_module(Universe::char_mirror(), module_handle());
493 java_lang_Class::set_module(Universe::long_mirror(), module_handle());
494 java_lang_Class::set_module(Universe::short_mirror(), module_handle());
495 java_lang_Class::set_module(Universe::void_mirror(), module_handle());
496
497 // Do the fixups for classes that have already been created.
498 GrowableArray <Klass*>* list = java_lang_Class::fixup_module_field_list();
499 int list_length = list->length();
500 for (int i = 0; i < list_length; i++) {
501 Klass* k = list->at(i);
502 assert(k->is_klass(), "List should only hold classes");
503 java_lang_Class::fixup_module_field(k, module_handle);
504 k->class_loader_data()->dec_keep_alive();
505 }
506
507 delete java_lang_Class::fixup_module_field_list();
508 java_lang_Class::set_fixup_module_field_list(NULL);
509 }
510
511 void ModuleEntryTable::print(outputStream* st) {
512 st->print_cr("Module Entry Table (table_size=%d, entries=%d)",
513 table_size(), number_of_entries());
514 for (int i = 0; i < table_size(); i++) {
515 for (ModuleEntry* probe = bucket(i);
516 probe != NULL;
517 probe = probe->next()) {
518 probe->print(st);
519 }
520 }
521 }
522
523 void ModuleEntry::print(outputStream* st) {
524 ResourceMark rm;
525 st->print_cr("entry " PTR_FORMAT " name %s module " PTR_FORMAT " loader %s version %s location %s strict %s next " PTR_FORMAT,
526 p2i(this),
527 name() == NULL ? UNNAMED_MODULE : name()->as_C_string(),
528 p2i(module()),
529 loader_data()->loader_name_and_id(),
530 version() != NULL ? version()->as_C_string() : "NULL",
531 location() != NULL ? location()->as_C_string() : "NULL",
532 BOOL_TO_STR(!can_read_all_unnamed()), p2i(next()));
533 }
534
535 void ModuleEntryTable::verify() {
536 verify_table<ModuleEntry>("Module Entry Table");
537 }
538
539 void ModuleEntry::verify() {
540 guarantee(loader_data() != NULL, "A module entry must be associated with a loader.");
541 }