1 /*
2 * Copyright (c) 2016, 2019, 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 if ((cld->is_the_null_class_loader_data() || cld->is_platform_class_loader_data()) &&
79 (strncmp(loc, "jrt:/java.", 10) == 0)) {
80 return false;
81 }
82 if ((ModuleEntryTable::javabase_moduleEntry()->version()->fast_compare(version()) == 0) &&
83 cld->is_permanent_class_loader_data() && (strncmp(loc, "jrt:/jdk.", 9) == 0)) {
84 return false;
85 }
86 }
87 return true;
88 }
89
90 void ModuleEntry::set_version(Symbol* version) {
91 if (_version != NULL) {
92 // _version symbol's refcounts are managed by ModuleEntry,
93 // must decrement the old one before updating.
94 _version->decrement_refcount();
95 }
96
97 _version = version;
98
99 if (version != NULL) {
100 version->increment_refcount();
101 }
102 }
103
104 // Returns the shared ProtectionDomain
105 oop ModuleEntry::shared_protection_domain() {
106 return _pd.resolve();
107 }
108
109 // Set the shared ProtectionDomain atomically
110 void ModuleEntry::set_shared_protection_domain(ClassLoaderData *loader_data,
111 Handle pd_h) {
112 // Create a handle for the shared ProtectionDomain and save it atomically.
113 // init_handle_locked checks if someone beats us setting the _pd cache.
114 loader_data->init_handle_locked(_pd, pd_h);
115 }
116
117 // Returns true if this module can read module m
118 bool ModuleEntry::can_read(ModuleEntry* m) const {
119 assert(m != NULL, "No module to lookup in this module's reads list");
120
121 // Unnamed modules read everyone and all modules
122 // read java.base. If either of these conditions
123 // hold, readability has been established.
124 if (!this->is_named() ||
125 (m == ModuleEntryTable::javabase_moduleEntry())) {
126 return true;
127 }
128
129 MutexLocker m1(Module_lock);
130 // This is a guard against possible race between agent threads that redefine
131 // or retransform classes in this module. Only one of them is adding the
132 // default read edges to the unnamed modules of the boot and app class loaders
133 // with an upcall to jdk.internal.module.Modules.transformedByAgent.
134 // At the same time, another thread can instrument the module classes by
135 // injecting dependencies that require the default read edges for resolution.
136 if (this->has_default_read_edges() && !m->is_named()) {
137 ClassLoaderData* cld = m->loader_data();
138 if (cld->is_the_null_class_loader_data() || cld->is_system_class_loader_data()) {
139 return true; // default read edge
140 }
141 }
142 if (!has_reads_list()) {
143 return false;
144 } else {
145 return _reads->contains(m);
146 }
147 }
148
149 // Add a new module to this module's reads list
150 void ModuleEntry::add_read(ModuleEntry* m) {
151 // Unnamed module is special cased and can read all modules
152 if (!is_named()) {
153 return;
154 }
155
156 MutexLocker m1(Module_lock);
157 if (m == NULL) {
158 set_can_read_all_unnamed();
159 } else {
160 if (_reads == NULL) {
161 // Lazily create a module's reads list
162 _reads = new (ResourceObj::C_HEAP, mtModule)GrowableArray<ModuleEntry*>(MODULE_READS_SIZE, true);
163 }
164
165 // Determine, based on this newly established read edge to module m,
166 // if this module's read list should be walked at a GC safepoint.
167 set_read_walk_required(m->loader_data());
168
169 // Establish readability to module m
170 _reads->append_if_missing(m);
171 }
172 }
173
174 // If the module's loader, that a read edge is being established to, is
175 // not the same loader as this module's and is not one of the 3 builtin
176 // class loaders, then this module's reads list must be walked at GC
177 // safepoint. Modules have the same life cycle as their defining class
178 // loaders and should be removed if dead.
179 void ModuleEntry::set_read_walk_required(ClassLoaderData* m_loader_data) {
180 assert(is_named(), "Cannot call set_read_walk_required on unnamed module");
181 assert_locked_or_safepoint(Module_lock);
182 if (!_must_walk_reads &&
183 loader_data() != m_loader_data &&
184 !m_loader_data->is_builtin_class_loader_data()) {
185 _must_walk_reads = true;
186 if (log_is_enabled(Trace, module)) {
187 ResourceMark rm;
188 log_trace(module)("ModuleEntry::set_read_walk_required(): module %s reads list must be walked",
189 (name() != NULL) ? name()->as_C_string() : UNNAMED_MODULE);
190 }
191 }
192 }
193
194 // Set whether the module is open, i.e. all its packages are unqualifiedly exported
195 void ModuleEntry::set_is_open(bool is_open) {
196 assert_lock_strong(Module_lock);
197 _is_open = is_open;
198 }
199
200 // Returns true if the module has a non-empty reads list. As such, the unnamed
201 // module will return false.
202 bool ModuleEntry::has_reads_list() const {
203 assert_locked_or_safepoint(Module_lock);
204 return ((_reads != NULL) && !_reads->is_empty());
205 }
206
207 // Purge dead module entries out of reads list.
208 void ModuleEntry::purge_reads() {
209 assert_locked_or_safepoint(Module_lock);
210
211 if (_must_walk_reads && has_reads_list()) {
212 // This module's _must_walk_reads flag will be reset based
213 // on the remaining live modules on the reads list.
214 _must_walk_reads = false;
215
216 if (log_is_enabled(Trace, module)) {
217 ResourceMark rm;
218 log_trace(module)("ModuleEntry::purge_reads(): module %s reads list being walked",
219 (name() != NULL) ? name()->as_C_string() : UNNAMED_MODULE);
220 }
221
222 // Go backwards because this removes entries that are dead.
223 int len = _reads->length();
224 for (int idx = len - 1; idx >= 0; idx--) {
225 ModuleEntry* module_idx = _reads->at(idx);
226 ClassLoaderData* cld_idx = module_idx->loader_data();
227 if (cld_idx->is_unloading()) {
228 _reads->delete_at(idx);
229 } else {
230 // Update the need to walk this module's reads based on live modules
231 set_read_walk_required(cld_idx);
232 }
233 }
234 }
235 }
236
237 void ModuleEntry::module_reads_do(ModuleClosure* f) {
238 assert_locked_or_safepoint(Module_lock);
239 assert(f != NULL, "invariant");
240
241 if (has_reads_list()) {
242 int reads_len = _reads->length();
243 for (int i = 0; i < reads_len; ++i) {
244 f->do_module(_reads->at(i));
245 }
246 }
247 }
248
249 void ModuleEntry::delete_reads() {
250 delete _reads;
251 _reads = NULL;
252 }
253
254 ModuleEntry* ModuleEntry::create_unnamed_module(ClassLoaderData* cld) {
255 // The java.lang.Module for this loader's
256 // corresponding unnamed module can be found in the java.lang.ClassLoader object.
257 oop module = java_lang_ClassLoader::unnamedModule(cld->class_loader());
258
259 // Ensure that the unnamed module was correctly set when the class loader was constructed.
260 // Guarantee will cause a recognizable crash if the user code has circumvented calling the ClassLoader constructor.
261 ResourceMark rm;
262 guarantee(java_lang_Module::is_instance(module),
263 "The unnamed module for ClassLoader %s, is null or not an instance of java.lang.Module. The class loader has not been initialized correctly.",
264 cld->loader_name_and_id());
265
266 ModuleEntry* unnamed_module = new_unnamed_module_entry(Handle(Thread::current(), module), cld);
267
268 // Store pointer to the ModuleEntry in the unnamed module's java.lang.Module object.
269 java_lang_Module::set_module_entry(module, unnamed_module);
270
271 return unnamed_module;
272 }
273
274 ModuleEntry* ModuleEntry::create_boot_unnamed_module(ClassLoaderData* cld) {
275 // For the boot loader, the java.lang.Module for the unnamed module
276 // is not known until a call to JVM_SetBootLoaderUnnamedModule is made. At
277 // this point initially create the ModuleEntry for the unnamed module.
278 ModuleEntry* unnamed_module = new_unnamed_module_entry(Handle(), cld);
279 assert(unnamed_module != NULL, "boot loader unnamed module should not be null");
280 return unnamed_module;
281 }
282
283 // When creating an unnamed module, this is called without holding the Module_lock.
284 // This is okay because the unnamed module gets created before the ClassLoaderData
285 // is available to other threads.
286 ModuleEntry* ModuleEntry::new_unnamed_module_entry(Handle module_handle, ClassLoaderData* cld) {
287 ModuleEntry* entry = NEW_C_HEAP_OBJ(ModuleEntry, mtModule);
288
289 // Initialize everything BasicHashtable would
290 entry->set_next(NULL);
291 entry->set_hash(0);
292 entry->set_literal(NULL);
293
294 // Initialize fields specific to a ModuleEntry
295 entry->init();
296
297 // Unnamed modules can read all other unnamed modules.
298 entry->set_can_read_all_unnamed();
299
300 if (!module_handle.is_null()) {
301 entry->set_module(cld->add_handle(module_handle));
302 }
303
304 entry->set_loader_data(cld);
305 entry->_is_open = true;
306
307 JFR_ONLY(INIT_ID(entry);)
308
309 return entry;
310 }
311
312 void ModuleEntry::delete_unnamed_module() {
313 // Do not need unlink_entry() since the unnamed module is not in the hashtable
314 FREE_C_HEAP_ARRAY(char, this);
315 }
316
317 ModuleEntryTable::ModuleEntryTable(int table_size)
318 : Hashtable<Symbol*, mtModule>(table_size, sizeof(ModuleEntry))
319 {
320 }
321
322 ModuleEntryTable::~ModuleEntryTable() {
323 // Walk through all buckets and all entries in each bucket,
324 // freeing each entry.
325 for (int i = 0; i < table_size(); ++i) {
326 for (ModuleEntry* m = bucket(i); m != NULL;) {
327 ModuleEntry* to_remove = m;
328 // read next before freeing.
329 m = m->next();
330
331 ResourceMark rm;
332 if (to_remove->name() != NULL) {
333 log_info(module, unload)("unloading module %s", to_remove->name()->as_C_string());
334 }
335 log_debug(module)("ModuleEntryTable: deleting module: %s", to_remove->name() != NULL ?
336 to_remove->name()->as_C_string() : UNNAMED_MODULE);
337
338 // Clean out the C heap allocated reads list first before freeing the entry
339 to_remove->delete_reads();
340 if (to_remove->name() != NULL) {
341 to_remove->name()->decrement_refcount();
342 }
343 if (to_remove->version() != NULL) {
344 to_remove->version()->decrement_refcount();
345 }
346 if (to_remove->location() != NULL) {
347 to_remove->location()->decrement_refcount();
348 }
349
350 // Unlink from the Hashtable prior to freeing
351 unlink_entry(to_remove);
352 FREE_C_HEAP_ARRAY(char, to_remove);
353 }
354 }
355 assert(number_of_entries() == 0, "should have removed all entries");
356 assert(new_entry_free_list() == NULL, "entry present on ModuleEntryTable's free list");
357 }
358
359 ModuleEntry* ModuleEntryTable::new_entry(unsigned int hash, Handle module_handle,
360 bool is_open, Symbol* name,
361 Symbol* version, Symbol* location,
362 ClassLoaderData* loader_data) {
363 assert(Module_lock->owned_by_self(), "should have the Module_lock");
364 ModuleEntry* entry = (ModuleEntry*)Hashtable<Symbol*, mtModule>::allocate_new_entry(hash, name);
365
366 // Initialize fields specific to a ModuleEntry
367 entry->init();
368 if (name != NULL) {
369 name->increment_refcount();
370 } else {
371 // Unnamed modules can read all other unnamed modules.
372 entry->set_can_read_all_unnamed();
373 }
374
375 if (!module_handle.is_null()) {
376 entry->set_module(loader_data->add_handle(module_handle));
377 }
378
379 entry->set_loader_data(loader_data);
380 entry->set_version(version);
381 entry->set_location(location);
382 entry->set_is_open(is_open);
383
384 if (ClassLoader::is_in_patch_mod_entries(name)) {
385 entry->set_is_patched();
386 if (log_is_enabled(Trace, module, patch)) {
387 ResourceMark rm;
388 log_trace(module, patch)("Marked module %s as patched from --patch-module",
389 name != NULL ? name->as_C_string() : UNNAMED_MODULE);
390 }
391 }
392
393 JFR_ONLY(INIT_ID(entry);)
394
395 return entry;
396 }
397
398 void ModuleEntryTable::add_entry(int index, ModuleEntry* new_entry) {
399 assert(Module_lock->owned_by_self(), "should have the Module_lock");
400 Hashtable<Symbol*, mtModule>::add_entry(index, (HashtableEntry<Symbol*, mtModule>*)new_entry);
401 }
402
403 // Create an entry in the class loader's module_entry_table. It is the
404 // caller's responsibility to ensure that the entry has not already been
405 // created.
406 ModuleEntry* ModuleEntryTable::locked_create_entry(Handle module_handle,
407 bool is_open,
408 Symbol* module_name,
409 Symbol* module_version,
410 Symbol* module_location,
411 ClassLoaderData* loader_data) {
412 assert(module_name != NULL, "ModuleEntryTable locked_create_entry should never be called for unnamed module.");
413 assert(Module_lock->owned_by_self(), "should have the Module_lock");
414 assert(lookup_only(module_name) == NULL, "Module already exists");
415 ModuleEntry* entry = new_entry(compute_hash(module_name), module_handle, is_open, module_name,
416 module_version, module_location, loader_data);
417 add_entry(index_for(module_name), entry);
418 return entry;
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 }