1 /*
2 * Copyright (c) 2016, 2017, 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 "classfile/classLoaderData.hpp"
27 #include "classfile/javaClasses.hpp"
28 #include "classfile/moduleEntry.hpp"
29 #include "logging/log.hpp"
30 #include "memory/resourceArea.hpp"
31 #include "oops/symbol.hpp"
32 #include "prims/jni.h"
33 #include "runtime/handles.inline.hpp"
34 #include "runtime/safepoint.hpp"
35 #include "trace/traceMacros.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 void ModuleEntry::set_location(Symbol* location) {
44 if (_location != NULL) {
45 // _location symbol's refcounts are managed by ModuleEntry,
46 // must decrement the old one before updating.
47 _location->decrement_refcount();
48 }
49
50 _location = location;
51
52 if (location != NULL) {
53 location->increment_refcount();
54 }
55 }
56
57 bool ModuleEntry::is_non_jdk_module() {
58 ResourceMark rm;
59 if (location() != NULL) {
60 const char* loc = location()->as_C_string();
61 if (strncmp(loc, "jrt:/java.", 10) != 0 && strncmp(loc, "jrt:/jdk.", 9) != 0) {
62 return true;
63 }
64 }
65 return false;
66 }
67
68 void ModuleEntry::set_version(Symbol* version) {
69 if (_version != NULL) {
70 // _version symbol's refcounts are managed by ModuleEntry,
71 // must decrement the old one before updating.
72 _version->decrement_refcount();
73 }
74
75 _version = version;
76
77 if (version != NULL) {
78 version->increment_refcount();
79 }
80 }
81
82 // Returns the shared ProtectionDomain
83 Handle ModuleEntry::shared_protection_domain() {
84 return Handle(JNIHandles::resolve(_pd));
85 }
86
87 // Set the shared ProtectionDomain atomically
88 void ModuleEntry::set_shared_protection_domain(ClassLoaderData *loader_data,
89 Handle pd_h) {
90 // Create a handle for the shared ProtectionDomain and save it atomically.
91 // If someone beats us setting the _pd cache, the created handle is destroyed.
92 jobject obj = loader_data->add_handle(pd_h);
93 if (Atomic::cmpxchg_ptr(obj, &_pd, NULL) != NULL) {
94 loader_data->remove_handle_unsafe(obj);
95 }
96 }
97
98 // Returns true if this module can read module m
99 bool ModuleEntry::can_read(ModuleEntry* m) const {
100 assert(m != NULL, "No module to lookup in this module's reads list");
101
102 // Unnamed modules read everyone and all modules
103 // read java.base. If either of these conditions
104 // hold, readability has been established.
105 if (!this->is_named() ||
106 (m == ModuleEntryTable::javabase_moduleEntry())) {
107 return true;
108 }
109
110 MutexLocker m1(Module_lock);
111 // This is a guard against possible race between agent threads that redefine
112 // or retransform classes in this module. Only one of them is adding the
113 // default read edges to the unnamed modules of the boot and app class loaders
114 // with an upcall to jdk.internal.module.Modules.transformedByAgent.
115 // At the same time, another thread can instrument the module classes by
116 // injecting dependencies that require the default read edges for resolution.
117 if (this->has_default_read_edges() && !m->is_named()) {
118 ClassLoaderData* cld = m->loader_data();
119 if (cld->is_the_null_class_loader_data() || cld->is_system_class_loader_data()) {
120 return true; // default read edge
121 }
122 }
123 if (!has_reads()) {
124 return false;
125 } else {
126 return _reads->contains(m);
127 }
128 }
129
130 // Add a new module to this module's reads list
131 void ModuleEntry::add_read(ModuleEntry* m) {
132 MutexLocker m1(Module_lock);
133 if (m == NULL) {
134 set_can_read_all_unnamed();
135 } else {
136 if (_reads == NULL) {
137 // Lazily create a module's reads list
138 _reads = new (ResourceObj::C_HEAP, mtModule)GrowableArray<ModuleEntry*>(MODULE_READS_SIZE, true);
139 }
140
141 // Determine, based on this newly established read edge to module m,
142 // if this module's read list should be walked at a GC safepoint.
143 set_read_walk_required(m->loader_data());
144
145 // Establish readability to module m
146 _reads->append_if_missing(m);
147 }
148 }
149
150 // If the module's loader, that a read edge is being established to, is
151 // not the same loader as this module's and is not one of the 3 builtin
152 // class loaders, then this module's reads list must be walked at GC
153 // safepoint. Modules have the same life cycle as their defining class
154 // loaders and should be removed if dead.
155 void ModuleEntry::set_read_walk_required(ClassLoaderData* m_loader_data) {
156 assert_locked_or_safepoint(Module_lock);
157 if (!_must_walk_reads &&
158 loader_data() != m_loader_data &&
159 !m_loader_data->is_builtin_class_loader_data()) {
160 _must_walk_reads = true;
161 if (log_is_enabled(Trace, modules)) {
162 ResourceMark rm;
163 log_trace(modules)("ModuleEntry::set_read_walk_required(): module %s reads list must be walked",
164 (name() != NULL) ? name()->as_C_string() : UNNAMED_MODULE);
165 }
166 }
167 }
168
169 // Set whether the module is open, i.e. all its packages are unqualifiedly exported
170 void ModuleEntry::set_is_open(bool is_open) {
171 assert_lock_strong(Module_lock);
172 _is_open = is_open;
173 }
174
175 bool ModuleEntry::has_reads() const {
176 assert_locked_or_safepoint(Module_lock);
177 return ((_reads != NULL) && !_reads->is_empty());
178 }
179
180 // Purge dead module entries out of reads list.
181 void ModuleEntry::purge_reads() {
182 assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint");
183
184 if (_must_walk_reads && has_reads()) {
185 // This module's _must_walk_reads flag will be reset based
186 // on the remaining live modules on the reads list.
187 _must_walk_reads = false;
188
189 if (log_is_enabled(Trace, modules)) {
190 ResourceMark rm;
191 log_trace(modules)("ModuleEntry::purge_reads(): module %s reads list being walked",
192 (name() != NULL) ? name()->as_C_string() : UNNAMED_MODULE);
193 }
194
195 // Go backwards because this removes entries that are dead.
196 int len = _reads->length();
197 for (int idx = len - 1; idx >= 0; idx--) {
198 ModuleEntry* module_idx = _reads->at(idx);
199 ClassLoaderData* cld_idx = module_idx->loader_data();
200 if (cld_idx->is_unloading()) {
201 _reads->delete_at(idx);
202 } else {
203 // Update the need to walk this module's reads based on live modules
204 set_read_walk_required(cld_idx);
205 }
206 }
207 }
208 }
209
210 void ModuleEntry::module_reads_do(ModuleClosure* const f) {
211 assert_locked_or_safepoint(Module_lock);
212 assert(f != NULL, "invariant");
213
214 if (has_reads()) {
215 int reads_len = _reads->length();
216 for (int i = 0; i < reads_len; ++i) {
217 f->do_module(_reads->at(i));
218 }
219 }
220 }
221
222 void ModuleEntry::delete_reads() {
223 assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint");
224 delete _reads;
225 _reads = NULL;
226 }
227
228 ModuleEntryTable::ModuleEntryTable(int table_size)
229 : Hashtable<Symbol*, mtModule>(table_size, sizeof(ModuleEntry)), _unnamed_module(NULL)
230 {
231 }
232
233 ModuleEntryTable::~ModuleEntryTable() {
234 assert_locked_or_safepoint(Module_lock);
235
236 // Walk through all buckets and all entries in each bucket,
237 // freeing each entry.
238 for (int i = 0; i < table_size(); ++i) {
239 for (ModuleEntry* m = bucket(i); m != NULL;) {
240 ModuleEntry* to_remove = m;
241 // read next before freeing.
242 m = m->next();
243
244 ResourceMark rm;
245 log_debug(modules)("ModuleEntryTable: deleting module: %s", to_remove->name() != NULL ?
246 to_remove->name()->as_C_string() : UNNAMED_MODULE);
247
248 // Clean out the C heap allocated reads list first before freeing the entry
249 to_remove->delete_reads();
250 if (to_remove->name() != NULL) {
251 to_remove->name()->decrement_refcount();
252 }
253 if (to_remove->version() != NULL) {
254 to_remove->version()->decrement_refcount();
255 }
256 if (to_remove->location() != NULL) {
257 to_remove->location()->decrement_refcount();
258 }
259
260 // Unlink from the Hashtable prior to freeing
261 unlink_entry(to_remove);
262 FREE_C_HEAP_ARRAY(char, to_remove);
263 }
264 }
265 assert(number_of_entries() == 0, "should have removed all entries");
266 assert(new_entry_free_list() == NULL, "entry present on ModuleEntryTable's free list");
267 free_buckets();
268 }
269
270 void ModuleEntryTable::create_unnamed_module(ClassLoaderData* loader_data) {
271 assert(Module_lock->owned_by_self(), "should have the Module_lock");
272
273 // Each ModuleEntryTable has exactly one unnamed module
274 if (loader_data->is_the_null_class_loader_data()) {
275 // For the boot loader, the java.lang.reflect.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 _unnamed_module = new_entry(0, Handle(NULL), true, NULL, NULL, NULL, loader_data);
279 } else {
280 // For all other class loaders the java.lang.reflect.Module for their
281 // corresponding unnamed module can be found in the java.lang.ClassLoader object.
282 oop module = java_lang_ClassLoader::unnamedModule(loader_data->class_loader());
283 _unnamed_module = new_entry(0, Handle(module), true, NULL, NULL, NULL, loader_data);
284
285 // Store pointer to the ModuleEntry in the unnamed module's java.lang.reflect.Module
286 // object.
287 java_lang_reflect_Module::set_module_entry(module, _unnamed_module);
288 }
289
290 // Add to bucket 0, no name to hash on
291 add_entry(0, _unnamed_module);
292 }
293
294 ModuleEntry* ModuleEntryTable::new_entry(unsigned int hash, Handle module_handle,
295 bool is_open, Symbol* name,
296 Symbol* version, Symbol* location,
297 ClassLoaderData* loader_data) {
298 assert(Module_lock->owned_by_self(), "should have the Module_lock");
299 ModuleEntry* entry = (ModuleEntry*) NEW_C_HEAP_ARRAY(char, entry_size(), mtModule);
300
301 // Initialize everything BasicHashtable would
302 entry->set_next(NULL);
303 entry->set_hash(hash);
304 entry->set_literal(name);
305
306 // Initialize fields specific to a ModuleEntry
307 entry->init();
308 if (name != NULL) {
309 name->increment_refcount();
310 } else {
311 // Unnamed modules can read all other unnamed modules.
312 entry->set_can_read_all_unnamed();
313 }
314
315 if (!module_handle.is_null()) {
316 entry->set_module(loader_data->add_handle(module_handle));
317 }
318
319 entry->set_loader_data(loader_data);
320 entry->set_version(version);
321 entry->set_location(location);
322 entry->set_is_open(is_open);
323
324 if (ClassLoader::is_in_patch_mod_entries(name)) {
325 entry->set_is_patched();
326 if (log_is_enabled(Trace, modules, patch)) {
327 ResourceMark rm;
328 log_trace(modules, patch)("Marked module %s as patched from --patch-module", name->as_C_string());
329 }
330 }
331
332 TRACE_INIT_ID(entry);
333
334 return entry;
335 }
336
337 void ModuleEntryTable::add_entry(int index, ModuleEntry* new_entry) {
338 assert(Module_lock->owned_by_self(), "should have the Module_lock");
339 Hashtable<Symbol*, mtModule>::add_entry(index, (HashtableEntry<Symbol*, mtModule>*)new_entry);
340 }
341
342 ModuleEntry* ModuleEntryTable::locked_create_entry_or_null(Handle module_handle,
343 bool is_open,
344 Symbol* module_name,
345 Symbol* module_version,
346 Symbol* module_location,
347 ClassLoaderData* loader_data) {
348 assert(module_name != NULL, "ModuleEntryTable locked_create_entry_or_null should never be called for unnamed module.");
349 assert(Module_lock->owned_by_self(), "should have the Module_lock");
350 // Check if module already exists.
351 if (lookup_only(module_name) != NULL) {
352 return NULL;
353 } else {
354 ModuleEntry* entry = new_entry(compute_hash(module_name), module_handle, is_open, module_name,
355 module_version, module_location, loader_data);
356 add_entry(index_for(module_name), entry);
357 return entry;
358 }
359 }
360
361 // lookup_only by Symbol* to find a ModuleEntry.
362 ModuleEntry* ModuleEntryTable::lookup_only(Symbol* name) {
363 if (name == NULL) {
364 // Return this table's unnamed module
365 return unnamed_module();
366 }
367 int index = index_for(name);
368 for (ModuleEntry* m = bucket(index); m != NULL; m = m->next()) {
369 if (m->name()->fast_compare(name) == 0) {
370 return m;
371 }
372 }
373 return NULL;
374 }
375
376 // Remove dead modules from all other alive modules' reads list.
377 // This should only occur at class unloading.
378 void ModuleEntryTable::purge_all_module_reads() {
379 assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint");
380 for (int i = 0; i < table_size(); i++) {
381 for (ModuleEntry* entry = bucket(i);
382 entry != NULL;
383 entry = entry->next()) {
384 entry->purge_reads();
385 }
386 }
387 }
388
389 void ModuleEntryTable::finalize_javabase(Handle module_handle, Symbol* version, Symbol* location) {
390 assert(Module_lock->owned_by_self(), "should have the Module_lock");
391 ClassLoaderData* boot_loader_data = ClassLoaderData::the_null_class_loader_data();
392 ModuleEntryTable* module_table = boot_loader_data->modules();
393
394 assert(module_table != NULL, "boot loader's ModuleEntryTable not defined");
395
396 if (module_handle.is_null()) {
397 fatal("Unable to finalize module definition for " JAVA_BASE_NAME);
398 }
399
400 // Set java.lang.reflect.Module, version and location for java.base
401 ModuleEntry* jb_module = javabase_moduleEntry();
402 assert(jb_module != NULL, JAVA_BASE_NAME " ModuleEntry not defined");
403 jb_module->set_version(version);
404 jb_module->set_location(location);
405 // Once java.base's ModuleEntry _module field is set with the known
406 // java.lang.reflect.Module, java.base is considered "defined" to the VM.
407 jb_module->set_module(boot_loader_data->add_handle(module_handle));
408
409 // Store pointer to the ModuleEntry for java.base in the java.lang.reflect.Module object.
410 java_lang_reflect_Module::set_module_entry(module_handle(), jb_module);
411 }
412
413 // Within java.lang.Class instances there is a java.lang.reflect.Module field
414 // that must be set with the defining module. During startup, prior to java.base's
415 // definition, classes needing their module field set are added to the fixup_module_list.
416 // Their module field is set once java.base's java.lang.reflect.Module is known to the VM.
417 void ModuleEntryTable::patch_javabase_entries(Handle module_handle) {
418 if (module_handle.is_null()) {
419 fatal("Unable to patch the module field of classes loaded prior to "
420 JAVA_BASE_NAME "'s definition, invalid java.lang.reflect.Module");
421 }
422
423 // Do the fixups for the basic primitive types
424 java_lang_Class::set_module(Universe::int_mirror(), module_handle());
425 java_lang_Class::set_module(Universe::float_mirror(), module_handle());
426 java_lang_Class::set_module(Universe::double_mirror(), module_handle());
427 java_lang_Class::set_module(Universe::byte_mirror(), module_handle());
428 java_lang_Class::set_module(Universe::bool_mirror(), module_handle());
429 java_lang_Class::set_module(Universe::char_mirror(), module_handle());
430 java_lang_Class::set_module(Universe::long_mirror(), module_handle());
431 java_lang_Class::set_module(Universe::short_mirror(), module_handle());
432 java_lang_Class::set_module(Universe::void_mirror(), module_handle());
433
434 // Do the fixups for classes that have already been created.
435 GrowableArray <Klass*>* list = java_lang_Class::fixup_module_field_list();
436 int list_length = list->length();
437 for (int i = 0; i < list_length; i++) {
438 Klass* k = list->at(i);
439 assert(k->is_klass(), "List should only hold classes");
440 java_lang_Class::fixup_module_field(KlassHandle(k), module_handle);
441 k->class_loader_data()->dec_keep_alive();
442 }
443
444 delete java_lang_Class::fixup_module_field_list();
445 java_lang_Class::set_fixup_module_field_list(NULL);
446 }
447
448 void ModuleEntryTable::print(outputStream* st) {
449 st->print_cr("Module Entry Table (table_size=%d, entries=%d)",
450 table_size(), number_of_entries());
451 for (int i = 0; i < table_size(); i++) {
452 for (ModuleEntry* probe = bucket(i);
453 probe != NULL;
454 probe = probe->next()) {
455 probe->print(st);
456 }
457 }
458 }
459
460 void ModuleEntry::print(outputStream* st) {
461 ResourceMark rm;
462 st->print_cr("entry " PTR_FORMAT " name %s module " PTR_FORMAT " loader %s version %s location %s strict %s next " PTR_FORMAT,
463 p2i(this),
464 name() == NULL ? UNNAMED_MODULE : name()->as_C_string(),
465 p2i(module()),
466 loader_data()->loader_name(),
467 version() != NULL ? version()->as_C_string() : "NULL",
468 location() != NULL ? location()->as_C_string() : "NULL",
469 BOOL_TO_STR(!can_read_all_unnamed()), p2i(next()));
470 }
471
472 void ModuleEntryTable::verify() {
473 int element_count = 0;
474 for (int i = 0; i < table_size(); i++) {
475 for (ModuleEntry* probe = bucket(i);
476 probe != NULL;
477 probe = probe->next()) {
478 probe->verify();
479 element_count++;
480 }
481 }
482 guarantee(number_of_entries() == element_count,
483 "Verify of Module Entry Table failed");
484 DEBUG_ONLY(verify_lookup_length((double)number_of_entries() / table_size(), "Module Entry Table"));
485 }
486
487 void ModuleEntry::verify() {
488 guarantee(loader_data() != NULL, "A module entry must be associated with a loader.");
489 }