/*
* Copyright (C) 2011 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#include "jni_internal.h"
#include <dlfcn.h>
#include "art_method.h"
#include "base/dumpable.h"
#include "base/mutex.h"
#include "base/stl_util.h"
#include "base/systrace.h"
#include "check_jni.h"
#include "dex_file-inl.h"
#include "fault_handler.h"
#include "indirect_reference_table-inl.h"
#include "mirror/class-inl.h"
#include "mirror/class_loader.h"
#include "nativebridge/native_bridge.h"
#include "nativeloader/native_loader.h"
#include "java_vm_ext.h"
#include "parsed_options.h"
#include "runtime-inl.h"
#include "runtime_options.h"
#include "ScopedLocalRef.h"
#include "scoped_thread_state_change.h"
#include "thread-inl.h"
#include "thread_list.h"
namespace art {
static size_t gGlobalsInitial = 512; // Arbitrary.
static size_t gGlobalsMax = 51200; // Arbitrary sanity check. (Must fit in 16 bits.)
static const size_t kWeakGlobalsInitial = 16; // Arbitrary.
static const size_t kWeakGlobalsMax = 51200; // Arbitrary sanity check. (Must fit in 16 bits.)
static bool IsBadJniVersion(int version) {
// We don't support JNI_VERSION_1_1. These are the only other valid versions.
return version != JNI_VERSION_1_2 && version != JNI_VERSION_1_4 && version != JNI_VERSION_1_6;
}
class SharedLibrary {
public:
SharedLibrary(JNIEnv* env, Thread* self, const std::string& path, void* handle,
jobject class_loader, void* class_loader_allocator)
: path_(path),
handle_(handle),
needs_native_bridge_(false),
class_loader_(env->NewWeakGlobalRef(class_loader)),
class_loader_allocator_(class_loader_allocator),
jni_on_load_lock_("JNI_OnLoad lock"),
jni_on_load_cond_("JNI_OnLoad condition variable", jni_on_load_lock_),
jni_on_load_thread_id_(self->GetThreadId()),
jni_on_load_result_(kPending) {
CHECK(class_loader_allocator_ != nullptr);
}
~SharedLibrary() {
Thread* self = Thread::Current();
if (self != nullptr) {
self->GetJniEnv()->DeleteWeakGlobalRef(class_loader_);
}
if (!needs_native_bridge_) {
android::CloseNativeLibrary(handle_);
}
}
jweak GetClassLoader() const {
return class_loader_;
}
const void* GetClassLoaderAllocator() const {
return class_loader_allocator_;
}
const std::string& GetPath() const {
return path_;
}
/*
* Check the result of an earlier call to JNI_OnLoad on this library.
* If the call has not yet finished in another thread, wait for it.
*/
bool CheckOnLoadResult()
REQUIRES(!jni_on_load_lock_) {
Thread* self = Thread::Current();
bool okay;
{
MutexLock mu(self, jni_on_load_lock_);
if (jni_on_load_thread_id_ == self->GetThreadId()) {
// Check this so we don't end up waiting for ourselves. We need to return "true" so the
// caller can continue.
LOG(INFO) << *self << " recursive attempt to load library " << "\"" << path_ << "\"";
okay = true;
} else {
while (jni_on_load_result_ == kPending) {
VLOG(jni) << "[" << *self << " waiting for \"" << path_ << "\" " << "JNI_OnLoad...]";
jni_on_load_cond_.Wait(self);
}
okay = (jni_on_load_result_ == kOkay);
VLOG(jni) << "[Earlier JNI_OnLoad for \"" << path_ << "\" "
<< (okay ? "succeeded" : "failed") << "]";
}
}
return okay;
}
void SetResult(bool result) REQUIRES(!jni_on_load_lock_) {
Thread* self = Thread::Current();
MutexLock mu(self, jni_on_load_lock_);
jni_on_load_result_ = result ? kOkay : kFailed;
jni_on_load_thread_id_ = 0;
// Broadcast a wakeup to anybody sleeping on the condition variable.
jni_on_load_cond_.Broadcast(self);
}
void SetNeedsNativeBridge() {
needs_native_bridge_ = true;
}
bool NeedsNativeBridge() const {
return needs_native_bridge_;
}
void* FindSymbol(const std::string& symbol_name, const char* shorty = nullptr) {
return NeedsNativeBridge()
? FindSymbolWithNativeBridge(symbol_name.c_str(), shorty)
: FindSymbolWithoutNativeBridge(symbol_name.c_str());
}
void* FindSymbolWithoutNativeBridge(const std::string& symbol_name) {
CHECK(!NeedsNativeBridge());
return dlsym(handle_, symbol_name.c_str());
}
void* FindSymbolWithNativeBridge(const std::string& symbol_name, const char* shorty) {
CHECK(NeedsNativeBridge());
uint32_t len = 0;
return android::NativeBridgeGetTrampoline(handle_, symbol_name.c_str(), shorty, len);
}
private:
enum JNI_OnLoadState {
kPending,
kFailed,
kOkay,
};
// Path to library "/system/lib/libjni.so".
const std::string path_;
// The void* returned by dlopen(3).
void* const handle_;
// True if a native bridge is required.
bool needs_native_bridge_;
// The ClassLoader this library is associated with, a weak global JNI reference that is
// created/deleted with the scope of the library.
const jweak class_loader_;
// Used to do equality check on class loaders so we can avoid decoding the weak root and read
// barriers that mess with class unloading.
const void* class_loader_allocator_;
// Guards remaining items.
Mutex jni_on_load_lock_ DEFAULT_MUTEX_ACQUIRED_AFTER;
// Wait for JNI_OnLoad in other thread.
ConditionVariable jni_on_load_cond_ GUARDED_BY(jni_on_load_lock_);
// Recursive invocation guard.
uint32_t jni_on_load_thread_id_ GUARDED_BY(jni_on_load_lock_);
// Result of earlier JNI_OnLoad call.
JNI_OnLoadState jni_on_load_result_ GUARDED_BY(jni_on_load_lock_);
};
// This exists mainly to keep implementation details out of the header file.
class Libraries {
public:
Libraries() {
}
~Libraries() {
STLDeleteValues(&libraries_);
}
// NO_THREAD_SAFETY_ANALYSIS since this may be called from Dumpable. Dumpable can't be annotated
// properly due to the template. The caller should be holding the jni_libraries_lock_.
void Dump(std::ostream& os) const NO_THREAD_SAFETY_ANALYSIS {
Locks::jni_libraries_lock_->AssertHeld(Thread::Current());
bool first = true;
for (const auto& library : libraries_) {
if (!first) {
os << ' ';
}
first = false;
os << library.first;
}
}
size_t size() const REQUIRES(Locks::jni_libraries_lock_) {
return libraries_.size();
}
SharedLibrary* Get(const std::string& path) REQUIRES(Locks::jni_libraries_lock_) {
auto it = libraries_.find(path);
return (it == libraries_.end()) ? nullptr : it->second;
}
void Put(const std::string& path, SharedLibrary* library)
REQUIRES(Locks::jni_libraries_lock_) {
libraries_.Put(path, library);
}
// See section 11.3 "Linking Native Methods" of the JNI spec.
void* FindNativeMethod(ArtMethod* m, std::string& detail)
REQUIRES(Locks::jni_libraries_lock_)
SHARED_REQUIRES(Locks::mutator_lock_) {
std::string jni_short_name(JniShortName(m));
std::string jni_long_name(JniLongName(m));
mirror::ClassLoader* const declaring_class_loader = m->GetDeclaringClass()->GetClassLoader();
ScopedObjectAccessUnchecked soa(Thread::Current());
void* const declaring_class_loader_allocator =
Runtime::Current()->GetClassLinker()->GetAllocatorForClassLoader(declaring_class_loader);
CHECK(declaring_class_loader_allocator != nullptr);
for (const auto& lib : libraries_) {
SharedLibrary* const library = lib.second;
// Use the allocator address for class loader equality to avoid unnecessary weak root decode.
if (library->GetClassLoaderAllocator() != declaring_class_loader_allocator) {
// We only search libraries loaded by the appropriate ClassLoader.
continue;
}
// Try the short name then the long name...
const char* shorty = library->NeedsNativeBridge()
? m->GetShorty()
: nullptr;
void* fn = library->FindSymbol(jni_short_name, shorty);
if (fn == nullptr) {
fn = library->FindSymbol(jni_long_name, shorty);
}
if (fn != nullptr) {
VLOG(jni) << "[Found native code for " << PrettyMethod(m)
<< " in \"" << library->GetPath() << "\"]";
return fn;
}
}
detail += "No implementation found for ";
detail += PrettyMethod(m);
detail += " (tried " + jni_short_name + " and " + jni_long_name + ")";
LOG(ERROR) << detail;
return nullptr;
}
// Unload native libraries with cleared class loaders.
void UnloadNativeLibraries()
REQUIRES(!Locks::jni_libraries_lock_)
SHARED_REQUIRES(Locks::mutator_lock_) {
ScopedObjectAccessUnchecked soa(Thread::Current());
std::vector<SharedLibrary*> unload_libraries;
{
MutexLock mu(soa.Self(), *Locks::jni_libraries_lock_);
for (auto it = libraries_.begin(); it != libraries_.end(); ) {
SharedLibrary* const library = it->second;
// If class loader is null then it was unloaded, call JNI_OnUnload.
const jweak class_loader = library->GetClassLoader();
// If class_loader is a null jobject then it is the boot class loader. We should not unload
// the native libraries of the boot class loader.
if (class_loader != nullptr &&
soa.Self()->IsJWeakCleared(class_loader)) {
unload_libraries.push_back(library);
it = libraries_.erase(it);
} else {
++it;
}
}
}
// Do this without holding the jni libraries lock to prevent possible deadlocks.
typedef void (*JNI_OnUnloadFn)(JavaVM*, void*);
for (auto library : unload_libraries) {
void* const sym = library->FindSymbol("JNI_OnUnload", nullptr);
if (sym == nullptr) {
VLOG(jni) << "[No JNI_OnUnload found in \"" << library->GetPath() << "\"]";
} else {
VLOG(jni) << "[JNI_OnUnload found for \"" << library->GetPath() << "\"]: Calling...";
JNI_OnUnloadFn jni_on_unload = reinterpret_cast<JNI_OnUnloadFn>(sym);
jni_on_unload(soa.Vm(), nullptr);
}
delete library;
}
}
private:
AllocationTrackingSafeMap<std::string, SharedLibrary*, kAllocatorTagJNILibraries> libraries_
GUARDED_BY(Locks::jni_libraries_lock_);
};
class JII {
public:
static jint DestroyJavaVM(JavaVM* vm) {
if (vm == nullptr) {
return JNI_ERR;
}
JavaVMExt* raw_vm = reinterpret_cast<JavaVMExt*>(vm);
delete raw_vm->GetRuntime();
android::ResetNativeLoader();
return JNI_OK;
}
static jint AttachCurrentThread(JavaVM* vm, JNIEnv** p_env, void* thr_args) {
return AttachCurrentThreadInternal(vm, p_env, thr_args, false);
}
static jint AttachCurrentThreadAsDaemon(JavaVM* vm, JNIEnv** p_env, void* thr_args) {
return AttachCurrentThreadInternal(vm, p_env, thr_args, true);
}
static jint DetachCurrentThread(JavaVM* vm) {
if (vm == nullptr || Thread::Current() == nullptr) {
return JNI_ERR;
}
JavaVMExt* raw_vm = reinterpret_cast<JavaVMExt*>(vm);
Runtime* runtime = raw_vm->GetRuntime();
runtime->DetachCurrentThread();
return JNI_OK;
}
static jint GetEnv(JavaVM* vm, void** env, jint version) {
// GetEnv always returns a JNIEnv* for the most current supported JNI version,
// and unlike other calls that take a JNI version doesn't care if you supply
// JNI_VERSION_1_1, which we don't otherwise support.
if (IsBadJniVersion(version) && version != JNI_VERSION_1_1) {
LOG(ERROR) << "Bad JNI version passed to GetEnv: " << version;
return JNI_EVERSION;
}
if (vm == nullptr || env == nullptr) {
return JNI_ERR;
}
Thread* thread = Thread::Current();
if (thread == nullptr) {
*env = nullptr;
return JNI_EDETACHED;
}
*env = thread->GetJniEnv();
return JNI_OK;
}
private:
static jint AttachCurrentThreadInternal(JavaVM* vm, JNIEnv** p_env, void* raw_args, bool as_daemon) {
if (vm == nullptr || p_env == nullptr) {
return JNI_ERR;
}
// Return immediately if we're already attached.
Thread* self = Thread::Current();
if (self != nullptr) {
*p_env = self->GetJniEnv();
return JNI_OK;
}
Runtime* runtime = reinterpret_cast<JavaVMExt*>(vm)->GetRuntime();
// No threads allowed in zygote mode.
if (runtime->IsZygote()) {
LOG(ERROR) << "Attempt to attach a thread in the zygote";
return JNI_ERR;
}
JavaVMAttachArgs* args = static_cast<JavaVMAttachArgs*>(raw_args);
const char* thread_name = nullptr;
jobject thread_group = nullptr;
if (args != nullptr) {
if (IsBadJniVersion(args->version)) {
LOG(ERROR) << "Bad JNI version passed to "
<< (as_daemon ? "AttachCurrentThreadAsDaemon" : "AttachCurrentThread") << ": "
<< args->version;
return JNI_EVERSION;
}
thread_name = args->name;
thread_group = args->group;
}
if (!runtime->AttachCurrentThread(thread_name, as_daemon, thread_group,
!runtime->IsAotCompiler())) {
*p_env = nullptr;
return JNI_ERR;
} else {
*p_env = Thread::Current()->GetJniEnv();
return JNI_OK;
}
}
};
const JNIInvokeInterface gJniInvokeInterface = {
nullptr, // reserved0
nullptr, // reserved1
nullptr, // reserved2
JII::DestroyJavaVM,
JII::AttachCurrentThread,
JII::DetachCurrentThread,
JII::GetEnv,
JII::AttachCurrentThreadAsDaemon
};
JavaVMExt::JavaVMExt(Runtime* runtime, const RuntimeArgumentMap& runtime_options)
: runtime_(runtime),
check_jni_abort_hook_(nullptr),
check_jni_abort_hook_data_(nullptr),
check_jni_(false), // Initialized properly in the constructor body below.
force_copy_(runtime_options.Exists(RuntimeArgumentMap::JniOptsForceCopy)),
tracing_enabled_(runtime_options.Exists(RuntimeArgumentMap::JniTrace)
|| VLOG_IS_ON(third_party_jni)),
trace_(runtime_options.GetOrDefault(RuntimeArgumentMap::JniTrace)),
globals_lock_("JNI global reference table lock"),
globals_(gGlobalsInitial, gGlobalsMax, kGlobal),
libraries_(new Libraries),
unchecked_functions_(&gJniInvokeInterface),
weak_globals_lock_("JNI weak global reference table lock", kJniWeakGlobalsLock),
weak_globals_(kWeakGlobalsInitial, kWeakGlobalsMax, kWeakGlobal),
allow_accessing_weak_globals_(true),
weak_globals_add_condition_("weak globals add condition", weak_globals_lock_) {
functions = unchecked_functions_;
SetCheckJniEnabled(runtime_options.Exists(RuntimeArgumentMap::CheckJni));
}
JavaVMExt::~JavaVMExt() {
}
void JavaVMExt::JniAbort(const char* jni_function_name, const char* msg) {
Thread* self = Thread::Current();
ScopedObjectAccess soa(self);
ArtMethod* current_method = self->GetCurrentMethod(nullptr);
std::ostringstream os;
os << "JNI DETECTED ERROR IN APPLICATION: " << msg;
if (jni_function_name != nullptr) {
os << "\n in call to " << jni_function_name;
}
// TODO: is this useful given that we're about to dump the calling thread's stack?
if (current_method != nullptr) {
os << "\n from " << PrettyMethod(current_method);
}
os << "\n";
self->Dump(os);
if (check_jni_abort_hook_ != nullptr) {
check_jni_abort_hook_(check_jni_abort_hook_data_, os.str());
} else {
// Ensure that we get a native stack trace for this thread.
ScopedThreadSuspension sts(self, kNative);
LOG(FATAL) << os.str();
UNREACHABLE();
}
}
void JavaVMExt::JniAbortV(const char* jni_function_name, const char* fmt, va_list ap) {
std::string msg;
StringAppendV(&msg, fmt, ap);
JniAbort(jni_function_name, msg.c_str());
}
void JavaVMExt::JniAbortF(const char* jni_function_name, const char* fmt, ...) {
va_list args;
va_start(args, fmt);
JniAbortV(jni_function_name, fmt, args);
va_end(args);
}
bool JavaVMExt::ShouldTrace(ArtMethod* method) {
// Fast where no tracing is enabled.
if (trace_.empty() && !VLOG_IS_ON(third_party_jni)) {
return false;
}
// Perform checks based on class name.
StringPiece class_name(method->GetDeclaringClassDescriptor());
if (!trace_.empty() && class_name.find(trace_) != std::string::npos) {
return true;
}
if (!VLOG_IS_ON(third_party_jni)) {
return false;
}
// Return true if we're trying to log all third-party JNI activity and 'method' doesn't look
// like part of Android.
static const char* gBuiltInPrefixes[] = {
"Landroid/",
"Lcom/android/",
"Lcom/google/android/",
"Ldalvik/",
"Ljava/",
"Ljavax/",
"Llibcore/",
"Lorg/apache/harmony/",
};
for (size_t i = 0; i < arraysize(gBuiltInPrefixes); ++i) {
if (class_name.starts_with(gBuiltInPrefixes[i])) {
return false;
}
}
return true;
}
jobject JavaVMExt::AddGlobalRef(Thread* self, mirror::Object* obj) {
// Check for null after decoding the object to handle cleared weak globals.
if (obj == nullptr) {
return nullptr;
}
WriterMutexLock mu(self, globals_lock_);
IndirectRef ref = globals_.Add(IRT_FIRST_SEGMENT, obj);
return reinterpret_cast<jobject>(ref);
}
jweak JavaVMExt::AddWeakGlobalRef(Thread* self, mirror::Object* obj) {
if (obj == nullptr) {
return nullptr;
}
MutexLock mu(self, weak_globals_lock_);
while (UNLIKELY(!MayAccessWeakGlobals(self))) {
weak_globals_add_condition_.WaitHoldingLocks(self);
}
IndirectRef ref = weak_globals_.Add(IRT_FIRST_SEGMENT, obj);
return reinterpret_cast<jweak>(ref);
}
void JavaVMExt::DeleteGlobalRef(Thread* self, jobject obj) {
if (obj == nullptr) {
return;
}
WriterMutexLock mu(self, globals_lock_);
if (!globals_.Remove(IRT_FIRST_SEGMENT, obj)) {
LOG(WARNING) << "JNI WARNING: DeleteGlobalRef(" << obj << ") "
<< "failed to find entry";
}
}
void JavaVMExt::DeleteWeakGlobalRef(Thread* self, jweak obj) {
if (obj == nullptr) {
return;
}
MutexLock mu(self, weak_globals_lock_);
if (!weak_globals_.Remove(IRT_FIRST_SEGMENT, obj)) {
LOG(WARNING) << "JNI WARNING: DeleteWeakGlobalRef(" << obj << ") "
<< "failed to find entry";
}
}
static void ThreadEnableCheckJni(Thread* thread, void* arg) {
bool* check_jni = reinterpret_cast<bool*>(arg);
thread->GetJniEnv()->SetCheckJniEnabled(*check_jni);
}
bool JavaVMExt::SetCheckJniEnabled(bool enabled) {
bool old_check_jni = check_jni_;
check_jni_ = enabled;
functions = enabled ? GetCheckJniInvokeInterface() : unchecked_functions_;
MutexLock mu(Thread::Current(), *Locks::thread_list_lock_);
runtime_->GetThreadList()->ForEach(ThreadEnableCheckJni, &check_jni_);
return old_check_jni;
}
void JavaVMExt::DumpForSigQuit(std::ostream& os) {
os << "JNI: CheckJNI is " << (check_jni_ ? "on" : "off");
if (force_copy_) {
os << " (with forcecopy)";
}
Thread* self = Thread::Current();
{
ReaderMutexLock mu(self, globals_lock_);
os << "; globals=" << globals_.Capacity();
}
{
MutexLock mu(self, weak_globals_lock_);
if (weak_globals_.Capacity() > 0) {
os << " (plus " << weak_globals_.Capacity() << " weak)";
}
}
os << '\n';
{
MutexLock mu(self, *Locks::jni_libraries_lock_);
os << "Libraries: " << Dumpable<Libraries>(*libraries_) << " (" << libraries_->size() << ")\n";
}
}
void JavaVMExt::DisallowNewWeakGlobals() {
CHECK(!kUseReadBarrier);
Thread* const self = Thread::Current();
MutexLock mu(self, weak_globals_lock_);
// DisallowNewWeakGlobals is only called by CMS during the pause. It is required to have the
// mutator lock exclusively held so that we don't have any threads in the middle of
// DecodeWeakGlobal.
Locks::mutator_lock_->AssertExclusiveHeld(self);
allow_accessing_weak_globals_.StoreSequentiallyConsistent(false);
}
void JavaVMExt::AllowNewWeakGlobals() {
CHECK(!kUseReadBarrier);
Thread* self = Thread::Current();
MutexLock mu(self, weak_globals_lock_);
allow_accessing_weak_globals_.StoreSequentiallyConsistent(true);
weak_globals_add_condition_.Broadcast(self);
}
void JavaVMExt::BroadcastForNewWeakGlobals() {
CHECK(kUseReadBarrier);
Thread* self = Thread::Current();
MutexLock mu(self, weak_globals_lock_);
weak_globals_add_condition_.Broadcast(self);
}
mirror::Object* JavaVMExt::DecodeGlobal(IndirectRef ref) {
return globals_.SynchronizedGet(ref);
}
void JavaVMExt::UpdateGlobal(Thread* self, IndirectRef ref, mirror::Object* result) {
WriterMutexLock mu(self, globals_lock_);
globals_.Update(ref, result);
}
inline bool JavaVMExt::MayAccessWeakGlobals(Thread* self) const {
return MayAccessWeakGlobalsUnlocked(self);
}
inline bool JavaVMExt::MayAccessWeakGlobalsUnlocked(Thread* self) const {
DCHECK(self != nullptr);
return kUseReadBarrier ?
self->GetWeakRefAccessEnabled() :
allow_accessing_weak_globals_.LoadSequentiallyConsistent();
}
mirror::Object* JavaVMExt::DecodeWeakGlobal(Thread* self, IndirectRef ref) {
// It is safe to access GetWeakRefAccessEnabled without the lock since CC uses checkpoints to call
// SetWeakRefAccessEnabled, and the other collectors only modify allow_accessing_weak_globals_
// when the mutators are paused.
// This only applies in the case where MayAccessWeakGlobals goes from false to true. In the other
// case, it may be racy, this is benign since DecodeWeakGlobalLocked does the correct behavior
// if MayAccessWeakGlobals is false.
DCHECK_EQ(GetIndirectRefKind(ref), kWeakGlobal);
if (LIKELY(MayAccessWeakGlobalsUnlocked(self))) {
return weak_globals_.SynchronizedGet(ref);
}
MutexLock mu(self, weak_globals_lock_);
return DecodeWeakGlobalLocked(self, ref);
}
mirror::Object* JavaVMExt::DecodeWeakGlobalLocked(Thread* self, IndirectRef ref) {
if (kDebugLocking) {
weak_globals_lock_.AssertHeld(self);
}
while (UNLIKELY(!MayAccessWeakGlobals(self))) {
weak_globals_add_condition_.WaitHoldingLocks(self);
}
return weak_globals_.Get(ref);
}
mirror::Object* JavaVMExt::DecodeWeakGlobalDuringShutdown(Thread* self, IndirectRef ref) {
DCHECK_EQ(GetIndirectRefKind(ref), kWeakGlobal);
DCHECK(Runtime::Current()->IsShuttingDown(self));
if (self != nullptr) {
return DecodeWeakGlobal(self, ref);
}
// self can be null during a runtime shutdown. ~Runtime()->~ClassLinker()->DecodeWeakGlobal().
if (!kUseReadBarrier) {
DCHECK(allow_accessing_weak_globals_.LoadSequentiallyConsistent());
}
return weak_globals_.SynchronizedGet(ref);
}
bool JavaVMExt::IsWeakGlobalCleared(Thread* self, IndirectRef ref) {
DCHECK_EQ(GetIndirectRefKind(ref), kWeakGlobal);
MutexLock mu(self, weak_globals_lock_);
while (UNLIKELY(!MayAccessWeakGlobals(self))) {
weak_globals_add_condition_.WaitHoldingLocks(self);
}
// When just checking a weak ref has been cleared, avoid triggering the read barrier in decode
// (DecodeWeakGlobal) so that we won't accidentally mark the object alive. Since the cleared
// sentinel is a non-moving object, we can compare the ref to it without the read barrier and
// decide if it's cleared.
return Runtime::Current()->IsClearedJniWeakGlobal(weak_globals_.Get<kWithoutReadBarrier>(ref));
}
void JavaVMExt::UpdateWeakGlobal(Thread* self, IndirectRef ref, mirror::Object* result) {
MutexLock mu(self, weak_globals_lock_);
weak_globals_.Update(ref, result);
}
void JavaVMExt::DumpReferenceTables(std::ostream& os) {
Thread* self = Thread::Current();
{
ReaderMutexLock mu(self, globals_lock_);
globals_.Dump(os);
}
{
MutexLock mu(self, weak_globals_lock_);
weak_globals_.Dump(os);
}
}
void JavaVMExt::UnloadNativeLibraries() {
libraries_.get()->UnloadNativeLibraries();
}
bool JavaVMExt::LoadNativeLibrary(JNIEnv* env,
const std::string& path,
jobject class_loader,
jstring library_path,
std::string* error_msg) {
error_msg->clear();
// See if we've already loaded this library. If we have, and the class loader
// matches, return successfully without doing anything.
// TODO: for better results we should canonicalize the pathname (or even compare
// inodes). This implementation is fine if everybody is using System.loadLibrary.
SharedLibrary* library;
Thread* self = Thread::Current();
{
// TODO: move the locking (and more of this logic) into Libraries.
MutexLock mu(self, *Locks::jni_libraries_lock_);
library = libraries_->Get(path);
}
void* class_loader_allocator = nullptr;
{
ScopedObjectAccess soa(env);
// As the incoming class loader is reachable/alive during the call of this function,
// it's okay to decode it without worrying about unexpectedly marking it alive.
mirror::ClassLoader* loader = soa.Decode<mirror::ClassLoader*>(class_loader);
ClassLinker* class_linker = Runtime::Current()->GetClassLinker();
if (class_linker->IsBootClassLoader(soa, loader)) {
loader = nullptr;
class_loader = nullptr;
}
class_loader_allocator = class_linker->GetAllocatorForClassLoader(loader);
CHECK(class_loader_allocator != nullptr);
}
if (library != nullptr) {
// Use the allocator pointers for class loader equality to avoid unnecessary weak root decode.
if (library->GetClassLoaderAllocator() != class_loader_allocator) {
// The library will be associated with class_loader. The JNI
// spec says we can't load the same library into more than one
// class loader.
StringAppendF(error_msg, "Shared library \"%s\" already opened by "
"ClassLoader %p; can't open in ClassLoader %p",
path.c_str(), library->GetClassLoader(), class_loader);
LOG(WARNING) << error_msg;
return false;
}
VLOG(jni) << "[Shared library \"" << path << "\" already loaded in "
<< " ClassLoader " << class_loader << "]";
if (!library->CheckOnLoadResult()) {
StringAppendF(error_msg, "JNI_OnLoad failed on a previous attempt "
"to load \"%s\"", path.c_str());
return false;
}
return true;
}
// Open the shared library. Because we're using a full path, the system
// doesn't have to search through LD_LIBRARY_PATH. (It may do so to
// resolve this library's dependencies though.)
// Failures here are expected when java.library.path has several entries
// and we have to hunt for the lib.
// Below we dlopen but there is no paired dlclose, this would be necessary if we supported
// class unloading. Libraries will only be unloaded when the reference count (incremented by
// dlopen) becomes zero from dlclose.
Locks::mutator_lock_->AssertNotHeld(self);
const char* path_str = path.empty() ? nullptr : path.c_str();
void* handle = android::OpenNativeLibrary(env,
runtime_->GetTargetSdkVersion(),
path_str,
class_loader,
library_path);
bool needs_native_bridge = false;
if (handle == nullptr) {
if (android::NativeBridgeIsSupported(path_str)) {
handle = android::NativeBridgeLoadLibrary(path_str, RTLD_NOW);
needs_native_bridge = true;
}
}
VLOG(jni) << "[Call to dlopen(\"" << path << "\", RTLD_NOW) returned " << handle << "]";
if (handle == nullptr) {
*error_msg = dlerror();
VLOG(jni) << "dlopen(\"" << path << "\", RTLD_NOW) failed: " << *error_msg;
return false;
}
if (env->ExceptionCheck() == JNI_TRUE) {
LOG(ERROR) << "Unexpected exception:";
env->ExceptionDescribe();
env->ExceptionClear();
}
// Create a new entry.
// TODO: move the locking (and more of this logic) into Libraries.
bool created_library = false;
{
// Create SharedLibrary ahead of taking the libraries lock to maintain lock ordering.
std::unique_ptr<SharedLibrary> new_library(
new SharedLibrary(env, self, path, handle, class_loader, class_loader_allocator));
MutexLock mu(self, *Locks::jni_libraries_lock_);
library = libraries_->Get(path);
if (library == nullptr) { // We won race to get libraries_lock.
library = new_library.release();
libraries_->Put(path, library);
created_library = true;
}
}
if (!created_library) {
LOG(INFO) << "WOW: we lost a race to add shared library: "
<< "\"" << path << "\" ClassLoader=" << class_loader;
return library->CheckOnLoadResult();
}
VLOG(jni) << "[Added shared library \"" << path << "\" for ClassLoader " << class_loader << "]";
bool was_successful = false;
void* sym;
if (needs_native_bridge) {
library->SetNeedsNativeBridge();
}
sym = library->FindSymbol("JNI_OnLoad", nullptr);
if (sym == nullptr) {
VLOG(jni) << "[No JNI_OnLoad found in \"" << path << "\"]";
was_successful = true;
} else {
// Call JNI_OnLoad. We have to override the current class
// loader, which will always be "null" since the stuff at the
// top of the stack is around Runtime.loadLibrary(). (See
// the comments in the JNI FindClass function.)
ScopedLocalRef<jobject> old_class_loader(env, env->NewLocalRef(self->GetClassLoaderOverride()));
self->SetClassLoaderOverride(class_loader);
VLOG(jni) << "[Calling JNI_OnLoad in \"" << path << "\"]";
typedef int (*JNI_OnLoadFn)(JavaVM*, void*);
JNI_OnLoadFn jni_on_load = reinterpret_cast<JNI_OnLoadFn>(sym);
int version = (*jni_on_load)(this, nullptr);
if (runtime_->GetTargetSdkVersion() != 0 && runtime_->GetTargetSdkVersion() <= 21) {
fault_manager.EnsureArtActionInFrontOfSignalChain();
}
self->SetClassLoaderOverride(old_class_loader.get());
if (version == JNI_ERR) {
StringAppendF(error_msg, "JNI_ERR returned from JNI_OnLoad in \"%s\"", path.c_str());
} else if (IsBadJniVersion(version)) {
StringAppendF(error_msg, "Bad JNI version returned from JNI_OnLoad in \"%s\": %d",
path.c_str(), version);
// It's unwise to call dlclose() here, but we can mark it
// as bad and ensure that future load attempts will fail.
// We don't know how far JNI_OnLoad got, so there could
// be some partially-initialized stuff accessible through
// newly-registered native method calls. We could try to
// unregister them, but that doesn't seem worthwhile.
} else {
was_successful = true;
}
VLOG(jni) << "[Returned " << (was_successful ? "successfully" : "failure")
<< " from JNI_OnLoad in \"" << path << "\"]";
}
library->SetResult(was_successful);
return was_successful;
}
void* JavaVMExt::FindCodeForNativeMethod(ArtMethod* m) {
CHECK(m->IsNative());
mirror::Class* c = m->GetDeclaringClass();
// If this is a static method, it could be called before the class has been initialized.
CHECK(c->IsInitializing()) << c->GetStatus() << " " << PrettyMethod(m);
std::string detail;
void* native_method;
Thread* self = Thread::Current();
{
MutexLock mu(self, *Locks::jni_libraries_lock_);
native_method = libraries_->FindNativeMethod(m, detail);
}
// Throwing can cause libraries_lock to be reacquired.
if (native_method == nullptr) {
self->ThrowNewException("Ljava/lang/UnsatisfiedLinkError;", detail.c_str());
}
return native_method;
}
void JavaVMExt::SweepJniWeakGlobals(IsMarkedVisitor* visitor) {
MutexLock mu(Thread::Current(), weak_globals_lock_);
Runtime* const runtime = Runtime::Current();
for (auto* entry : weak_globals_) {
// Need to skip null here to distinguish between null entries and cleared weak ref entries.
if (!entry->IsNull()) {
// Since this is called by the GC, we don't need a read barrier.
mirror::Object* obj = entry->Read<kWithoutReadBarrier>();
mirror::Object* new_obj = visitor->IsMarked(obj);
if (new_obj == nullptr) {
new_obj = runtime->GetClearedJniWeakGlobal();
}
*entry = GcRoot<mirror::Object>(new_obj);
}
}
}
void JavaVMExt::TrimGlobals() {
WriterMutexLock mu(Thread::Current(), globals_lock_);
globals_.Trim();
}
void JavaVMExt::VisitRoots(RootVisitor* visitor) {
Thread* self = Thread::Current();
ReaderMutexLock mu(self, globals_lock_);
globals_.VisitRoots(visitor, RootInfo(kRootJNIGlobal));
// The weak_globals table is visited by the GC itself (because it mutates the table).
}
// JNI Invocation interface.
extern "C" jint JNI_CreateJavaVM(JavaVM** p_vm, JNIEnv** p_env, void* vm_args) {
ScopedTrace trace(__FUNCTION__);
const JavaVMInitArgs* args = static_cast<JavaVMInitArgs*>(vm_args);
if (IsBadJniVersion(args->version)) {
LOG(ERROR) << "Bad JNI version passed to CreateJavaVM: " << args->version;
return JNI_EVERSION;
}
RuntimeOptions options;
for (int i = 0; i < args->nOptions; ++i) {
JavaVMOption* option = &args->options[i];
options.push_back(std::make_pair(std::string(option->optionString), option->extraInfo));
}
bool ignore_unrecognized = args->ignoreUnrecognized;
if (!Runtime::Create(options, ignore_unrecognized)) {
return JNI_ERR;
}
// Initialize native loader. This step makes sure we have
// everything set up before we start using JNI.
android::InitializeNativeLoader();
Runtime* runtime = Runtime::Current();
bool started = runtime->Start();
if (!started) {
delete Thread::Current()->GetJniEnv();
delete runtime->GetJavaVM();
LOG(WARNING) << "CreateJavaVM failed";
return JNI_ERR;
}
*p_env = Thread::Current()->GetJniEnv();
*p_vm = runtime->GetJavaVM();
return JNI_OK;
}
extern "C" jint JNI_GetCreatedJavaVMs(JavaVM** vms_buf, jsize buf_len, jsize* vm_count) {
Runtime* runtime = Runtime::Current();
if (runtime == nullptr || buf_len == 0) {
*vm_count = 0;
} else {
*vm_count = 1;
vms_buf[0] = runtime->GetJavaVM();
}
return JNI_OK;
}
// Historically unsupported.
extern "C" jint JNI_GetDefaultJavaVMInitArgs(void* /*vm_args*/) {
return JNI_ERR;
}
} // namespace art