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_locked_or_safepoint(Module_lock);
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 delete _reads;
249 _reads = NULL;
250 }
251
252 ModuleEntry* ModuleEntry::create_unnamed_module(ClassLoaderData* cld) {
253 // The java.lang.Module for this loader's
254 // corresponding unnamed module can be found in the java.lang.ClassLoader object.
255 oop module = java_lang_ClassLoader::unnamedModule(cld->class_loader());
256
257 // Ensure that the unnamed module was correctly set when the class loader was constructed.
258 // Guarantee will cause a recognizable crash if the user code has circumvented calling the ClassLoader constructor.
259 ResourceMark rm;
260 guarantee(java_lang_Module::is_instance(module),
261 "The unnamed module for ClassLoader %s, is null or not an instance of java.lang.Module. The class loader has not been initialized correctly.",
262 cld->loader_name_and_id());
263
264 ModuleEntry* unnamed_module = new_unnamed_module_entry(Handle(Thread::current(), module), cld);
265
266 // Store pointer to the ModuleEntry in the unnamed module's java.lang.Module object.
267 java_lang_Module::set_module_entry(module, unnamed_module);
268
269 return unnamed_module;
270 }
271
272 ModuleEntry* ModuleEntry::create_boot_unnamed_module(ClassLoaderData* cld) {
273 // For the boot loader, the java.lang.Module for the unnamed module
274 // is not known until a call to JVM_SetBootLoaderUnnamedModule is made. At
275 // this point initially create the ModuleEntry for the unnamed module.
276 ModuleEntry* unnamed_module = new_unnamed_module_entry(Handle(), cld);
277 assert(unnamed_module != NULL, "boot loader unnamed module should not be null");
278 return unnamed_module;
279 }
280
281 // When creating an unnamed module, this is called without holding the Module_lock.
282 // This is okay because the unnamed module gets created before the ClassLoaderData
283 // is available to other threads.
284 ModuleEntry* ModuleEntry::new_unnamed_module_entry(Handle module_handle, ClassLoaderData* cld) {
285 ModuleEntry* entry = (ModuleEntry*) NEW_C_HEAP_ARRAY(char, sizeof(ModuleEntry), mtModule);
286
287 // Initialize everything BasicHashtable would
288 entry->set_next(NULL);
289 entry->set_hash(0);
290 entry->set_literal(NULL);
291
292 // Initialize fields specific to a ModuleEntry
293 entry->init();
294
295 // Unnamed modules can read all other unnamed modules.
296 entry->set_can_read_all_unnamed();
297
298 if (!module_handle.is_null()) {
299 entry->set_module(cld->add_handle(module_handle));
300 }
301
302 entry->set_loader_data(cld);
303 entry->_is_open = true;
304
305 JFR_ONLY(INIT_ID(entry);)
306
307 return entry;
308 }
309
310 void ModuleEntry::delete_unnamed_module() {
311 // Do not need unlink_entry() since the unnamed module is not in the hashtable
312 FREE_C_HEAP_ARRAY(char, this);
313 }
314
315 ModuleEntryTable::ModuleEntryTable(int table_size)
316 : Hashtable<Symbol*, mtModule>(table_size, sizeof(ModuleEntry))
317 {
318 }
319
320 ModuleEntryTable::~ModuleEntryTable() {
321 // Walk through all buckets and all entries in each bucket,
322 // freeing each entry.
323 for (int i = 0; i < table_size(); ++i) {
324 for (ModuleEntry* m = bucket(i); m != NULL;) {
325 ModuleEntry* to_remove = m;
326 // read next before freeing.
327 m = m->next();
328
329 ResourceMark rm;
330 if (to_remove->name() != NULL) {
331 log_info(module, unload)("unloading module %s", to_remove->name()->as_C_string());
332 }
333 log_debug(module)("ModuleEntryTable: deleting module: %s", to_remove->name() != NULL ?
334 to_remove->name()->as_C_string() : UNNAMED_MODULE);
335
336 // Clean out the C heap allocated reads list first before freeing the entry
337 to_remove->delete_reads();
338 if (to_remove->name() != NULL) {
339 to_remove->name()->decrement_refcount();
340 }
341 if (to_remove->version() != NULL) {
342 to_remove->version()->decrement_refcount();
343 }
344 if (to_remove->location() != NULL) {
345 to_remove->location()->decrement_refcount();
346 }
347
348 // Unlink from the Hashtable prior to freeing
349 unlink_entry(to_remove);
350 FREE_C_HEAP_ARRAY(char, to_remove);
351 }
352 }
353 assert(number_of_entries() == 0, "should have removed all entries");
354 assert(new_entry_free_list() == NULL, "entry present on ModuleEntryTable's free list");
355 free_buckets();
356 }
357
358 ModuleEntry* ModuleEntryTable::new_entry(unsigned int hash, Handle module_handle,
359 bool is_open, Symbol* name,
360 Symbol* version, Symbol* location,
361 ClassLoaderData* loader_data) {
362 assert(Module_lock->owned_by_self(), "should have the Module_lock");
363 ModuleEntry* entry = (ModuleEntry*)Hashtable<Symbol*, mtModule>::allocate_new_entry(hash, name);
364
365 // Initialize fields specific to a ModuleEntry
366 entry->init();
367 if (name != NULL) {
368 name->increment_refcount();
369 } else {
370 // Unnamed modules can read all other unnamed modules.
371 entry->set_can_read_all_unnamed();
372 }
373
374 if (!module_handle.is_null()) {
375 entry->set_module(loader_data->add_handle(module_handle));
376 }
377
378 entry->set_loader_data(loader_data);
379 entry->set_version(version);
380 entry->set_location(location);
381 entry->set_is_open(is_open);
382
383 if (ClassLoader::is_in_patch_mod_entries(name)) {
384 entry->set_is_patched();
385 if (log_is_enabled(Trace, module, patch)) {
386 ResourceMark rm;
387 log_trace(module, patch)("Marked module %s as patched from --patch-module",
388 name != NULL ? name->as_C_string() : UNNAMED_MODULE);
389 }
390 }
391
392 JFR_ONLY(INIT_ID(entry);)
393
394 return entry;
395 }
396
397 void ModuleEntryTable::add_entry(int index, ModuleEntry* new_entry) {
398 assert(Module_lock->owned_by_self(), "should have the Module_lock");
399 Hashtable<Symbol*, mtModule>::add_entry(index, (HashtableEntry<Symbol*, mtModule>*)new_entry);
400 }
401
402 ModuleEntry* ModuleEntryTable::locked_create_entry_or_null(Handle module_handle,
403 bool is_open,
404 Symbol* module_name,
405 Symbol* module_version,
406 Symbol* module_location,
407 ClassLoaderData* loader_data) {
408 assert(module_name != NULL, "ModuleEntryTable locked_create_entry_or_null should never be called for unnamed module.");
409 assert(Module_lock->owned_by_self(), "should have the Module_lock");
410 // Check if module already exists.
411 if (lookup_only(module_name) != NULL) {
412 return NULL;
413 } else {
414 ModuleEntry* entry = new_entry(compute_hash(module_name), module_handle, is_open, module_name,
415 module_version, module_location, loader_data);
416 add_entry(index_for(module_name), entry);
417 return entry;
418 }
419 }
420
421 // lookup_only by Symbol* to find a ModuleEntry.
422 ModuleEntry* ModuleEntryTable::lookup_only(Symbol* name) {
423 assert(name != NULL, "name cannot be NULL");
424 int index = index_for(name);
425 for (ModuleEntry* m = bucket(index); m != NULL; m = m->next()) {
426 if (m->name()->fast_compare(name) == 0) {
427 return m;
428 }
429 }
430 return NULL;
431 }
432
433 // Remove dead modules from all other alive modules' reads list.
434 // This should only occur at class unloading.
435 void ModuleEntryTable::purge_all_module_reads() {
436 assert_locked_or_safepoint(Module_lock);
437 for (int i = 0; i < table_size(); i++) {
438 for (ModuleEntry* entry = bucket(i);
439 entry != NULL;
440 entry = entry->next()) {
441 entry->purge_reads();
442 }
443 }
444 }
445
446 void ModuleEntryTable::finalize_javabase(Handle module_handle, Symbol* version, Symbol* location) {
447 assert(Module_lock->owned_by_self(), "should have the Module_lock");
448 ClassLoaderData* boot_loader_data = ClassLoaderData::the_null_class_loader_data();
449 ModuleEntryTable* module_table = boot_loader_data->modules();
450
451 assert(module_table != NULL, "boot loader's ModuleEntryTable not defined");
452
453 if (module_handle.is_null()) {
454 fatal("Unable to finalize module definition for " JAVA_BASE_NAME);
455 }
456
457 // Set java.lang.Module, version and location for java.base
458 ModuleEntry* jb_module = javabase_moduleEntry();
459 assert(jb_module != NULL, JAVA_BASE_NAME " ModuleEntry not defined");
460 jb_module->set_version(version);
461 jb_module->set_location(location);
462 // Once java.base's ModuleEntry _module field is set with the known
463 // java.lang.Module, java.base is considered "defined" to the VM.
464 jb_module->set_module(boot_loader_data->add_handle(module_handle));
465
466 // Store pointer to the ModuleEntry for java.base in the java.lang.Module object.
467 java_lang_Module::set_module_entry(module_handle(), jb_module);
468 }
469
470 // Within java.lang.Class instances there is a java.lang.Module field that must
471 // be set with the defining module. During startup, prior to java.base's definition,
472 // classes needing their module field set are added to the fixup_module_list.
473 // Their module field is set once java.base's java.lang.Module is known to the VM.
474 void ModuleEntryTable::patch_javabase_entries(Handle module_handle) {
475 if (module_handle.is_null()) {
476 fatal("Unable to patch the module field of classes loaded prior to "
477 JAVA_BASE_NAME "'s definition, invalid java.lang.Module");
478 }
479
480 // Do the fixups for the basic primitive types
481 java_lang_Class::set_module(Universe::int_mirror(), module_handle());
482 java_lang_Class::set_module(Universe::float_mirror(), module_handle());
483 java_lang_Class::set_module(Universe::double_mirror(), module_handle());
484 java_lang_Class::set_module(Universe::byte_mirror(), module_handle());
485 java_lang_Class::set_module(Universe::bool_mirror(), module_handle());
486 java_lang_Class::set_module(Universe::char_mirror(), module_handle());
487 java_lang_Class::set_module(Universe::long_mirror(), module_handle());
488 java_lang_Class::set_module(Universe::short_mirror(), module_handle());
489 java_lang_Class::set_module(Universe::void_mirror(), module_handle());
490
491 // Do the fixups for classes that have already been created.
492 GrowableArray <Klass*>* list = java_lang_Class::fixup_module_field_list();
493 int list_length = list->length();
494 for (int i = 0; i < list_length; i++) {
495 Klass* k = list->at(i);
496 assert(k->is_klass(), "List should only hold classes");
497 java_lang_Class::fixup_module_field(k, module_handle);
498 k->class_loader_data()->dec_keep_alive();
499 }
500
501 delete java_lang_Class::fixup_module_field_list();
502 java_lang_Class::set_fixup_module_field_list(NULL);
503 }
504
505 void ModuleEntryTable::print(outputStream* st) {
506 st->print_cr("Module Entry Table (table_size=%d, entries=%d)",
507 table_size(), number_of_entries());
508 for (int i = 0; i < table_size(); i++) {
509 for (ModuleEntry* probe = bucket(i);
510 probe != NULL;
511 probe = probe->next()) {
512 probe->print(st);
513 }
514 }
515 }
516
517 void ModuleEntry::print(outputStream* st) {
518 ResourceMark rm;
519 st->print_cr("entry " PTR_FORMAT " name %s module " PTR_FORMAT " loader %s version %s location %s strict %s next " PTR_FORMAT,
520 p2i(this),
521 name() == NULL ? UNNAMED_MODULE : name()->as_C_string(),
522 p2i(module()),
523 loader_data()->loader_name_and_id(),
524 version() != NULL ? version()->as_C_string() : "NULL",
525 location() != NULL ? location()->as_C_string() : "NULL",
526 BOOL_TO_STR(!can_read_all_unnamed()), p2i(next()));
527 }
528
529 void ModuleEntryTable::verify() {
530 verify_table<ModuleEntry>("Module Entry Table");
531 }
532
533 void ModuleEntry::verify() {
534 guarantee(loader_data() != NULL, "A module entry must be associated with a loader.");
535 }