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/*
* Copyright (c) 2003, 2022, Oracle and/or its affiliates. All rights reserved.
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
* This code is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License version 2 only, as
* published by the Free Software Foundation.
*
* This code is distributed in the hope that it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
* version 2 for more details (a copy is included in the LICENSE file that
* accompanied this code).
*
* You should have received a copy of the GNU General Public License version
* 2 along with this work; if not, write to the Free Software Foundation,
* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
*
* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
* or visit www.oracle.com if you need additional information or have any
* questions.
*
*/
#include "precompiled.hpp"
#include "classfile/classLoaderData.inline.hpp"
#include "classfile/dictionary.hpp"
#include "classfile/javaClasses.hpp"
#include "classfile/protectionDomainCache.hpp"
#include "classfile/systemDictionary.hpp"
#include "classfile/vmSymbols.hpp"
#include "logging/log.hpp"
#include "logging/logStream.hpp"
#include "memory/iterator.hpp"
#include "memory/metaspaceClosure.hpp"
#include "memory/resourceArea.hpp"
#include "memory/universe.hpp"
#include "oops/klass.inline.hpp"
#include "oops/method.hpp"
#include "oops/oop.inline.hpp"
#include "oops/oopHandle.inline.hpp"
#include "runtime/arguments.hpp"
#include "runtime/handles.inline.hpp"
#include "runtime/javaCalls.hpp"
#include "runtime/mutexLocker.hpp"
#include "runtime/safepointVerifiers.hpp"
#include "utilities/concurrentHashTable.inline.hpp"
#include "utilities/growableArray.hpp"
#include "utilities/tableStatistics.hpp"
// 2^24 is max size, like StringTable.
const size_t END_SIZE = 24;
// If a chain gets to 100 something might be wrong
const size_t REHASH_LEN = 100;
Dictionary::Dictionary(ClassLoaderData* loader_data, size_t table_size)
: _number_of_entries(0), _loader_data(loader_data) {
size_t start_size_log_2 = MAX2(ceil_log2(table_size), (size_t)2); // 2 is minimum size even though some dictionaries only have one entry
size_t current_size = ((size_t)1) << start_size_log_2;
log_info(class, loader, data)("Dictionary start size: " SIZE_FORMAT " (" SIZE_FORMAT ")",
current_size, start_size_log_2);
_table = new ConcurrentTable(start_size_log_2, END_SIZE, REHASH_LEN);
}
Dictionary::~Dictionary() {
// This deletes the table and all the nodes, by calling free_node in Config.
delete _table;
}
uintx Dictionary::Config::get_hash(Value const& value, bool* is_dead) {
return value->instance_klass()->name()->identity_hash();
}
void* Dictionary::Config::allocate_node(void* context, size_t size, Value const& value) {
return AllocateHeap(size, mtClass);
}
void Dictionary::Config::free_node(void* context, void* memory, Value const& value) {
delete value; // Call DictionaryEntry destructor
FreeHeap(memory);
}
DictionaryEntry::DictionaryEntry(InstanceKlass* klass) : _instance_klass(klass) {
release_set_pd_set(nullptr);
}
DictionaryEntry::~DictionaryEntry() {
// avoid recursion when deleting linked list
// pd_set is accessed during a safepoint.
// This doesn't require a lock because nothing is reading this
// entry anymore. The ClassLoader is dead.
while (pd_set_acquire() != NULL) {
ProtectionDomainEntry* to_delete = pd_set_acquire();
release_set_pd_set(to_delete->next_acquire());
delete to_delete;
}
}
const int _resize_load_trigger = 5; // load factor that will trigger the resize
int Dictionary::table_size() const {
return 1 << _table->get_size_log2(Thread::current());
}
bool Dictionary::check_if_needs_resize() {
return ((_number_of_entries > (_resize_load_trigger * table_size())) &&
!_table->is_max_size_reached());
}
bool DictionaryEntry::is_valid_protection_domain(Handle protection_domain) {
return protection_domain() == NULL || !java_lang_System::allow_security_manager()
? true
: contains_protection_domain(protection_domain());
}
// Reading the pd_set on each DictionaryEntry is lock free and cannot safepoint.
// Adding and deleting entries is under the SystemDictionary_lock
// Deleting unloaded entries on ClassLoaderData for dictionaries that are not unloaded
// is a three step process:
// moving the entries to a separate list, handshake to wait for
// readers to complete (see NSV here), and then actually deleting the entries.
// Deleting entries is done by the ServiceThread when triggered by class unloading.
bool DictionaryEntry::contains_protection_domain(oop protection_domain) const {
assert(Thread::current()->is_Java_thread() || SafepointSynchronize::is_at_safepoint(),
"can only be called by a JavaThread or at safepoint");
// This cannot safepoint while reading the protection domain set.
NoSafepointVerifier nsv;
#ifdef ASSERT
if (protection_domain == instance_klass()->protection_domain()) {
// Ensure this doesn't show up in the pd_set (invariant)
bool in_pd_set = false;
for (ProtectionDomainEntry* current = pd_set_acquire();
current != NULL;
current = current->next_acquire()) {
if (current->object_no_keepalive() == protection_domain) {
in_pd_set = true;
break;
}
}
if (in_pd_set) {
assert(false, "A klass's protection domain should not show up "
"in its sys. dict. PD set");
}
}
#endif /* ASSERT */
if (protection_domain == instance_klass()->protection_domain()) {
// Succeeds trivially
return true;
}
for (ProtectionDomainEntry* current = pd_set_acquire();
current != NULL;
current = current->next_acquire()) {
if (current->object_no_keepalive() == protection_domain) {
return true;
}
}
return false;
}
void DictionaryEntry::add_protection_domain(ClassLoaderData* loader_data, Handle protection_domain) {
assert_lock_strong(SystemDictionary_lock);
if (!contains_protection_domain(protection_domain())) {
WeakHandle obj = ProtectionDomainCacheTable::add_if_absent(protection_domain);
// Additions and deletions hold the SystemDictionary_lock, readers are lock-free
ProtectionDomainEntry* new_head = new ProtectionDomainEntry(obj, _pd_set);
release_set_pd_set(new_head);
}
LogTarget(Trace, protectiondomain) lt;
if (lt.is_enabled()) {
ResourceMark rm;
LogStream ls(lt);
ls.print("adding protection domain for class %s", instance_klass()->name()->as_C_string());
ls.print(" class loader: ");
loader_data->class_loader()->print_value_on(&ls);
ls.print(" protection domain: ");
protection_domain->print_value_on(&ls);
ls.print(" ");
print_count(&ls);
ls.cr();
}
}
// Just the classes from defining class loaders
void Dictionary::classes_do(void f(InstanceKlass*)) {
auto doit = [&] (DictionaryEntry** value) {
InstanceKlass* k = (*value)->instance_klass();
if (loader_data() == k->class_loader_data()) {
f(k);
}
return true;
};
_table->do_scan(Thread::current(), doit);
}
// All classes, and their class loaders, including initiating class loaders
void Dictionary::all_entries_do(KlassClosure* closure) {
auto all_doit = [&] (DictionaryEntry** value) {
InstanceKlass* k = (*value)->instance_klass();
closure->do_klass(k);
return true;
};
_table->do_scan(Thread::current(), all_doit);
}
// Used to scan and relocate the classes during CDS archive dump.
void Dictionary::classes_do(MetaspaceClosure* it) {
Arguments::assert_is_dumping_archive();
auto push = [&] (DictionaryEntry** value) {
InstanceKlass** k = (*value)->instance_klass_addr();
it->push(k);
return true;
};
_table->do_scan(Thread::current(), push);
}
class DictionaryLookup : StackObj {
private:
Symbol* _name;
public:
DictionaryLookup(Symbol* name) : _name(name) { }
uintx get_hash() const {
return _name->identity_hash();
}
bool equals(DictionaryEntry** value, bool* is_dead) {
DictionaryEntry *entry = *value;
*is_dead = false;
return (entry->instance_klass()->name() == _name);
}
};
// Add a loaded class to the dictionary.
void Dictionary::add_klass(JavaThread* current, Symbol* class_name,
InstanceKlass* obj) {
assert_locked_or_safepoint(SystemDictionary_lock); // doesn't matter now
assert(obj != NULL, "adding NULL obj");
assert(obj->name() == class_name, "sanity check on name");
DictionaryEntry* entry = new DictionaryEntry(obj);
DictionaryLookup lookup(class_name);
bool needs_rehashing, clean_hint;
bool created = _table->insert(current, lookup, entry, &needs_rehashing, &clean_hint);
assert(created, "should be because we have a lock");
assert (!needs_rehashing, "should never need rehashing");
assert(!clean_hint, "no class should be unloaded");
_number_of_entries++; // still locked
// This table can be resized while another thread is reading it.
if (check_if_needs_resize()) {
_table->grow(current);
// It would be nice to have a JFR event here, add some logging.
LogTarget(Info, class, loader, data) lt;
if (lt.is_enabled()) {
ResourceMark rm;
LogStream ls(<);
ls.print("Dictionary resized to %d entries %d for ", table_size(), _number_of_entries);
loader_data()->print_value_on(&ls);
}
}
}
// This routine does not lock the dictionary.
//
// Since readers don't hold a lock, we must make sure that system
// dictionary entries are only removed at a safepoint (when only one
// thread is running), and are added to in a safe way (all links must
// be updated in an MT-safe manner).
//
// Callers should be aware that an entry could be added just after
// the table is read here, so the caller will not see the new entry.
// The entry may be accessed by the VM thread in verification.
DictionaryEntry* Dictionary::get_entry(Thread* current,
Symbol* class_name) {
DictionaryLookup lookup(class_name);
DictionaryEntry* result = nullptr;
auto get = [&] (DictionaryEntry** value) {
// function called if value is found so is never null
result = (*value);
};
bool needs_rehashing = false;
_table->get(current, lookup, get, &needs_rehashing);
assert (!needs_rehashing, "should never need rehashing");
return result;
}
InstanceKlass* Dictionary::find(Thread* current, Symbol* name,
Handle protection_domain) {
NoSafepointVerifier nsv;
DictionaryEntry* entry = get_entry(current, name);
if (entry != NULL && entry->is_valid_protection_domain(protection_domain)) {
return entry->instance_klass();
} else {
return NULL;
}
}
InstanceKlass* Dictionary::find_class(Thread* current,
Symbol* name) {
assert_locked_or_safepoint(SystemDictionary_lock);
DictionaryEntry* entry = get_entry(current, name);
return (entry != NULL) ? entry->instance_klass() : NULL;
}
void Dictionary::add_protection_domain(JavaThread* current,
InstanceKlass* klass,
Handle protection_domain) {
assert(java_lang_System::allow_security_manager(), "only needed if security manager allowed");
Symbol* klass_name = klass->name();
DictionaryEntry* entry = get_entry(current, klass_name);
assert(entry != NULL,"entry must be present, we just created it");
assert(protection_domain() != NULL,
"real protection domain should be present");
entry->add_protection_domain(loader_data(), protection_domain);
#ifdef ASSERT
assert(loader_data() != ClassLoaderData::the_null_class_loader_data(), "doesn't make sense");
#endif
assert(entry->contains_protection_domain(protection_domain()),
"now protection domain should be present");
}
inline bool Dictionary::is_valid_protection_domain(JavaThread* current,
Symbol* name,
Handle protection_domain) {
DictionaryEntry* entry = get_entry(current, name);
return entry->is_valid_protection_domain(protection_domain);
}
void Dictionary::validate_protection_domain(InstanceKlass* klass,
Handle class_loader,
Handle protection_domain,
TRAPS) {
assert(class_loader() != NULL, "Should not call this");
assert(protection_domain() != NULL, "Should not call this");
if (!java_lang_System::allow_security_manager() ||
is_valid_protection_domain(THREAD, klass->name(), protection_domain)) {
return;
}
// We only have to call checkPackageAccess if there's a security manager installed.
if (java_lang_System::has_security_manager()) {
// This handle and the class_loader handle passed in keeps this class from
// being unloaded through several GC points.
// The class_loader handle passed in is the initiating loader.
Handle mirror(THREAD, klass->java_mirror());
// Now we have to call back to java to check if the initating class has access
InstanceKlass* system_loader = vmClasses::ClassLoader_klass();
JavaValue result(T_VOID);
JavaCalls::call_special(&result,
class_loader,
system_loader,
vmSymbols::checkPackageAccess_name(),
vmSymbols::class_protectiondomain_signature(),
mirror,
protection_domain,
THREAD);
LogTarget(Debug, protectiondomain) lt;
if (lt.is_enabled()) {
ResourceMark rm(THREAD);
// Print out trace information
LogStream ls(lt);
ls.print_cr("Checking package access");
ls.print("class loader: ");
class_loader()->print_value_on(&ls);
ls.print(" protection domain: ");
protection_domain()->print_value_on(&ls);
ls.print(" loading: "); klass->print_value_on(&ls);
if (HAS_PENDING_EXCEPTION) {
ls.print_cr(" DENIED !!!!!!!!!!!!!!!!!!!!!");
} else {
ls.print_cr(" granted");
}
}
if (HAS_PENDING_EXCEPTION) return;
}
// If no exception has been thrown, we have validated the protection domain
// Insert the protection domain of the initiating class into the set.
// We still have to add the protection_domain to the dictionary in case a new
// security manager is installed later. Calls to load the same class with class loader
// and protection domain are expected to succeed.
{
MutexLocker mu(THREAD, SystemDictionary_lock);
add_protection_domain(THREAD, klass,
protection_domain);
}
}
// During class loading we may have cached a protection domain that has
// since been unreferenced, so this entry should be cleared.
void Dictionary::clean_cached_protection_domains(GrowableArray<ProtectionDomainEntry*>* delete_list) {
assert(Thread::current()->is_Java_thread(), "only called by JavaThread");
assert_lock_strong(SystemDictionary_lock);
assert(!loader_data()->has_class_mirror_holder(), "cld should have a ClassLoader holder not a Class holder");
if (loader_data()->is_the_null_class_loader_data()) {
// Classes in the boot loader are not loaded with protection domains
return;
}
auto clean_entries = [&] (DictionaryEntry** value) {
DictionaryEntry* probe = *value;
Klass* e = probe->instance_klass();
ProtectionDomainEntry* current = probe->pd_set_acquire();
ProtectionDomainEntry* prev = NULL;
while (current != NULL) {
if (current->object_no_keepalive() == NULL) {
LogTarget(Debug, protectiondomain) lt;
if (lt.is_enabled()) {
ResourceMark rm;
// Print out trace information
LogStream ls(lt);
ls.print_cr("PD in set is not alive:");
ls.print("class loader: "); _loader_data->class_loader()->print_value_on(&ls);
ls.print(" loading: "); probe->instance_klass()->print_value_on(&ls);
ls.cr();
}
if (probe->pd_set_acquire() == current) {
probe->release_set_pd_set(current->next_acquire());
} else {
assert(prev != NULL, "should be set by alive entry");
prev->release_set_next(current->next_acquire());
}
// Mark current for deletion but in the meantime it can still be
// traversed.
delete_list->push(current);
current = current->next_acquire();
} else {
prev = current;
current = current->next_acquire();
}
}
return true;
};
_table->do_scan(Thread::current(), clean_entries);
}
void DictionaryEntry::verify_protection_domain_set() {
assert(SafepointSynchronize::is_at_safepoint(), "must only be called as safepoint");
for (ProtectionDomainEntry* current = pd_set_acquire(); // accessed at a safepoint
current != NULL;
current = current->next_acquire()) {
guarantee(oopDesc::is_oop_or_null(current->object_no_keepalive()), "Invalid oop");
}
}
void DictionaryEntry::print_count(outputStream *st) {
assert_locked_or_safepoint(SystemDictionary_lock);
int count = 0;
for (ProtectionDomainEntry* current = pd_set_acquire();
current != NULL;
current = current->next_acquire()) {
count++;
}
st->print("pd set count = #%d", count);
}
// ----------------------------------------------------------------------------
void Dictionary::print_size(outputStream* st) const {
st->print_cr("Java dictionary (table_size=%d, classes=%d)",
table_size(), _number_of_entries);
}
void Dictionary::print_on(outputStream* st) const {
ResourceMark rm;
assert(loader_data() != NULL, "loader data should not be null");
assert(!loader_data()->has_class_mirror_holder(), "cld should have a ClassLoader holder not a Class holder");
print_size(st);
st->print_cr("^ indicates that initiating loader is different from defining loader");
auto printer = [&] (DictionaryEntry** entry) {
DictionaryEntry* probe = *entry;
Klass* e = probe->instance_klass();
bool is_defining_class =
(_loader_data == e->class_loader_data());
st->print(" %s%s", is_defining_class ? " " : "^", e->external_name());
ClassLoaderData* cld = e->class_loader_data();
if (!_loader_data->is_the_null_class_loader_data()) {
// Class loader output for the dictionary for the null class loader data is
// redundant and obvious.
st->print(", ");
cld->print_value_on(st);
st->print(", ");
probe->print_count(st);
}
st->cr();
return true;
};
if (SafepointSynchronize::is_at_safepoint()) {
_table->do_safepoint_scan(printer);
} else {
_table->do_scan(Thread::current(), printer);
}
tty->cr();
}
void DictionaryEntry::verify() {
Klass* e = instance_klass();
guarantee(e->is_instance_klass(),
"Verify of dictionary failed");
e->verify();
verify_protection_domain_set();
}
void Dictionary::verify() {
guarantee(_number_of_entries >= 0, "Verify of dictionary failed");
ClassLoaderData* cld = loader_data();
// class loader must be present; a null class loader is the
// bootstrap loader
guarantee(cld != NULL &&
(cld->is_the_null_class_loader_data() || cld->class_loader_no_keepalive()->is_instance()),
"checking type of class_loader");
auto verifier = [&] (DictionaryEntry** val) {
(*val)->verify();
return true;
};
_table->do_safepoint_scan(verifier);
}
void Dictionary::print_table_statistics(outputStream* st, const char* table_name) {
static TableStatistics ts;
auto sz = [&] (DictionaryEntry** val) {
return sizeof(**val);
};
ts = _table->statistics_get(Thread::current(), sz, ts);
ts.print(st, table_name);
}
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