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gerrit-public.fairphone.software / platform / art / a59af8aeaad8fe7d68d8f8de63eab9cf85b6ab31 / . / openjdkjvmti / ti_redefine.cc
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/* Copyright (C) 2016 The Android Open Source Project
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
* This file implements interfaces from the file jvmti.h. This implementation
* is licensed under the same terms as the file jvmti.h. The
* copyright and license information for the file jvmti.h follows.
*
* Copyright (c) 2003, 2011, 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. Oracle designates this
* particular file as subject to the "Classpath" exception as provided
* by Oracle in the LICENSE file that accompanied this code.
*
* 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 "ti_redefine.h"
#include <algorithm>
#include <atomic>
#include <iterator>
#include <limits>
#include <sstream>
#include <string_view>
#include <unordered_map>
#include <android-base/logging.h>
#include <android-base/stringprintf.h>
#include "alloc_manager.h"
#include "android-base/macros.h"
#include "android-base/thread_annotations.h"
#include "art_field-inl.h"
#include "art_field.h"
#include "art_jvmti.h"
#include "art_method-inl.h"
#include "art_method.h"
#include "base/array_ref.h"
#include "base/casts.h"
#include "base/enums.h"
#include "base/globals.h"
#include "base/length_prefixed_array.h"
#include "base/utils.h"
#include "class_linker-inl.h"
#include "class_linker.h"
#include "class_root.h"
#include "class_status.h"
#include "debugger.h"
#include "dex/art_dex_file_loader.h"
#include "dex/class_accessor-inl.h"
#include "dex/class_accessor.h"
#include "dex/dex_file.h"
#include "dex/dex_file_loader.h"
#include "dex/dex_file_types.h"
#include "dex/primitive.h"
#include "dex/signature-inl.h"
#include "dex/signature.h"
#include "events-inl.h"
#include "events.h"
#include "gc/allocation_listener.h"
#include "gc/heap.h"
#include "gc/heap-inl.h"
#include "gc/heap-visit-objects-inl.h"
#include "handle.h"
#include "handle_scope.h"
#include "instrumentation.h"
#include "intern_table.h"
#include "jdwp/jdwp.h"
#include "jdwp/jdwp_constants.h"
#include "jdwp/jdwp_event.h"
#include "jdwp/object_registry.h"
#include "jit/jit.h"
#include "jit/jit_code_cache.h"
#include "jni/jni_env_ext-inl.h"
#include "jni/jni_id_manager.h"
#include "jvmti.h"
#include "jvmti_allocator.h"
#include "linear_alloc.h"
#include "mirror/array-alloc-inl.h"
#include "mirror/array.h"
#include "mirror/class-alloc-inl.h"
#include "mirror/class-inl.h"
#include "mirror/class-refvisitor-inl.h"
#include "mirror/class.h"
#include "mirror/class_ext-inl.h"
#include "mirror/dex_cache-inl.h"
#include "mirror/dex_cache.h"
#include "mirror/executable-inl.h"
#include "mirror/field-inl.h"
#include "mirror/method.h"
#include "mirror/method_handle_impl-inl.h"
#include "mirror/object.h"
#include "mirror/object_array-alloc-inl.h"
#include "mirror/object_array-inl.h"
#include "mirror/object_array.h"
#include "mirror/string.h"
#include "mirror/var_handle.h"
#include "nativehelper/scoped_local_ref.h"
#include "non_debuggable_classes.h"
#include "obj_ptr.h"
#include "object_lock.h"
#include "reflective_value_visitor.h"
#include "runtime.h"
#include "runtime_globals.h"
#include "scoped_thread_state_change.h"
#include "stack.h"
#include "thread.h"
#include "thread_list.h"
#include "ti_breakpoint.h"
#include "ti_class_definition.h"
#include "ti_class_loader.h"
#include "ti_heap.h"
#include "ti_logging.h"
#include "ti_thread.h"
#include "transform.h"
#include "verifier/class_verifier.h"
#include "verifier/verifier_enums.h"
#include "well_known_classes.h"
#include "write_barrier.h"
namespace openjdkjvmti {
// Debug check to force us to directly check we saw all methods and fields exactly once directly.
// Normally we don't need to do this since if any are missing the count will be different
constexpr bool kCheckAllMethodsSeenOnce = art::kIsDebugBuild;
using android::base::StringPrintf;
// A helper that fills in a classes obsolete_methods_ and obsolete_dex_caches_ classExt fields as
// they are created. This ensures that we can always call any method of an obsolete ArtMethod object
// almost as soon as they are created since the GetObsoleteDexCache method will succeed.
class ObsoleteMap {
public:
art::ArtMethod* FindObsoleteVersion(art::ArtMethod* original) const
REQUIRES(art::Locks::mutator_lock_, art::Roles::uninterruptible_) {
auto method_pair = id_map_.find(original);
if (method_pair != id_map_.end()) {
art::ArtMethod* res = obsolete_methods_->GetElementPtrSize<art::ArtMethod*>(
method_pair->second, art::kRuntimePointerSize);
DCHECK(res != nullptr);
return res;
} else {
return nullptr;
}
}
void RecordObsolete(art::ArtMethod* original, art::ArtMethod* obsolete)
REQUIRES(art::Locks::mutator_lock_, art::Roles::uninterruptible_) {
DCHECK(original != nullptr);
DCHECK(obsolete != nullptr);
int32_t slot = next_free_slot_++;
DCHECK_LT(slot, obsolete_methods_->GetLength());
DCHECK(nullptr ==
obsolete_methods_->GetElementPtrSize<art::ArtMethod*>(slot, art::kRuntimePointerSize));
DCHECK(nullptr == obsolete_dex_caches_->Get(slot));
obsolete_methods_->SetElementPtrSize(slot, obsolete, art::kRuntimePointerSize);
obsolete_dex_caches_->Set(slot, original_dex_cache_);
id_map_.insert({original, slot});
}
ObsoleteMap(art::ObjPtr<art::mirror::PointerArray> obsolete_methods,
art::ObjPtr<art::mirror::ObjectArray<art::mirror::DexCache>> obsolete_dex_caches,
art::ObjPtr<art::mirror::DexCache> original_dex_cache)
: next_free_slot_(0),
obsolete_methods_(obsolete_methods),
obsolete_dex_caches_(obsolete_dex_caches),
original_dex_cache_(original_dex_cache) {
// Figure out where the first unused slot in the obsolete_methods_ array is.
while (obsolete_methods_->GetElementPtrSize<art::ArtMethod*>(
next_free_slot_, art::kRuntimePointerSize) != nullptr) {
DCHECK(obsolete_dex_caches_->Get(next_free_slot_) != nullptr);
next_free_slot_++;
}
// Sanity check that the same slot in obsolete_dex_caches_ is free.
DCHECK(obsolete_dex_caches_->Get(next_free_slot_) == nullptr);
}
struct ObsoleteMethodPair {
art::ArtMethod* old_method;
art::ArtMethod* obsolete_method;
};
class ObsoleteMapIter {
public:
using iterator_category = std::forward_iterator_tag;
using value_type = ObsoleteMethodPair;
using difference_type = ptrdiff_t;
using pointer = void; // Unsupported.
using reference = void; // Unsupported.
ObsoleteMethodPair operator*() const
REQUIRES(art::Locks::mutator_lock_, art::Roles::uninterruptible_) {
art::ArtMethod* obsolete = map_->obsolete_methods_->GetElementPtrSize<art::ArtMethod*>(
iter_->second, art::kRuntimePointerSize);
DCHECK(obsolete != nullptr);
return { iter_->first, obsolete };
}
bool operator==(ObsoleteMapIter other) const {
return map_ == other.map_ && iter_ == other.iter_;
}
bool operator!=(ObsoleteMapIter other) const {
return !(*this == other);
}
ObsoleteMapIter operator++(int) {
ObsoleteMapIter retval = *this;
++(*this);
return retval;
}
ObsoleteMapIter operator++() {
++iter_;
return *this;
}
private:
ObsoleteMapIter(const ObsoleteMap* map,
std::unordered_map<art::ArtMethod*, int32_t>::const_iterator iter)
: map_(map), iter_(iter) {}
const ObsoleteMap* map_;
std::unordered_map<art::ArtMethod*, int32_t>::const_iterator iter_;
friend class ObsoleteMap;
};
ObsoleteMapIter end() const {
return ObsoleteMapIter(this, id_map_.cend());
}
ObsoleteMapIter begin() const {
return ObsoleteMapIter(this, id_map_.cbegin());
}
private:
int32_t next_free_slot_;
std::unordered_map<art::ArtMethod*, int32_t> id_map_;
// Pointers to the fields in mirror::ClassExt. These can be held as ObjPtr since this is only used
// when we have an exclusive mutator_lock_ (i.e. all threads are suspended).
art::ObjPtr<art::mirror::PointerArray> obsolete_methods_;
art::ObjPtr<art::mirror::ObjectArray<art::mirror::DexCache>> obsolete_dex_caches_;
art::ObjPtr<art::mirror::DexCache> original_dex_cache_;
};
// This visitor walks thread stacks and allocates and sets up the obsolete methods. It also does
// some basic sanity checks that the obsolete method is sane.
class ObsoleteMethodStackVisitor : public art::StackVisitor {
protected:
ObsoleteMethodStackVisitor(
art::Thread* thread,
art::LinearAlloc* allocator,
const std::unordered_set<art::ArtMethod*>& obsoleted_methods,
ObsoleteMap* obsolete_maps)
: StackVisitor(thread,
/*context=*/nullptr,
StackVisitor::StackWalkKind::kIncludeInlinedFrames),
allocator_(allocator),
obsoleted_methods_(obsoleted_methods),
obsolete_maps_(obsolete_maps) { }
~ObsoleteMethodStackVisitor() override {}
public:
// Returns true if we successfully installed obsolete methods on this thread, filling
// obsolete_maps_ with the translations if needed. Returns false and fills error_msg if we fail.
// The stack is cleaned up when we fail.
static void UpdateObsoleteFrames(
art::Thread* thread,
art::LinearAlloc* allocator,
const std::unordered_set<art::ArtMethod*>& obsoleted_methods,
ObsoleteMap* obsolete_maps)
REQUIRES(art::Locks::mutator_lock_) {
ObsoleteMethodStackVisitor visitor(thread,
allocator,
obsoleted_methods,
obsolete_maps);
visitor.WalkStack();
}
bool VisitFrame() override REQUIRES(art::Locks::mutator_lock_) {
art::ScopedAssertNoThreadSuspension snts("Fixing up the stack for obsolete methods.");
art::ArtMethod* old_method = GetMethod();
if (obsoleted_methods_.find(old_method) != obsoleted_methods_.end()) {
// We cannot ensure that the right dex file is used in inlined frames so we don't support
// redefining them.
DCHECK(!IsInInlinedFrame()) << "Inlined frames are not supported when using redefinition: "
<< old_method->PrettyMethod() << " is inlined into "
<< GetOuterMethod()->PrettyMethod();
art::ArtMethod* new_obsolete_method = obsolete_maps_->FindObsoleteVersion(old_method);
if (new_obsolete_method == nullptr) {
// Create a new Obsolete Method and put it in the list.
art::Runtime* runtime = art::Runtime::Current();
art::ClassLinker* cl = runtime->GetClassLinker();
auto ptr_size = cl->GetImagePointerSize();
const size_t method_size = art::ArtMethod::Size(ptr_size);
auto* method_storage = allocator_->Alloc(art::Thread::Current(), method_size);
CHECK(method_storage != nullptr) << "Unable to allocate storage for obsolete version of '"
<< old_method->PrettyMethod() << "'";
new_obsolete_method = new (method_storage) art::ArtMethod();
new_obsolete_method->CopyFrom(old_method, ptr_size);
DCHECK_EQ(new_obsolete_method->GetDeclaringClass(), old_method->GetDeclaringClass());
new_obsolete_method->SetIsObsolete();
new_obsolete_method->SetDontCompile();
cl->SetEntryPointsForObsoleteMethod(new_obsolete_method);
obsolete_maps_->RecordObsolete(old_method, new_obsolete_method);
}
DCHECK(new_obsolete_method != nullptr);
SetMethod(new_obsolete_method);
}
return true;
}
private:
// The linear allocator we should use to make new methods.
art::LinearAlloc* allocator_;
// The set of all methods which could be obsoleted.
const std::unordered_set<art::ArtMethod*>& obsoleted_methods_;
// A map from the original to the newly allocated obsolete method for frames on this thread. The
// values in this map are added to the obsolete_methods_ (and obsolete_dex_caches_) fields of
// the redefined classes ClassExt as it is filled.
ObsoleteMap* obsolete_maps_;
};
template <RedefinitionType kType>
jvmtiError
Redefiner::IsModifiableClassGeneric(jvmtiEnv* env, jclass klass, jboolean* is_redefinable) {
if (env == nullptr) {
return ERR(INVALID_ENVIRONMENT);
}
art::Thread* self = art::Thread::Current();
art::ScopedObjectAccess soa(self);
art::StackHandleScope<1> hs(self);
art::ObjPtr<art::mirror::Object> obj(self->DecodeJObject(klass));
if (obj.IsNull() || !obj->IsClass()) {
return ERR(INVALID_CLASS);
}
art::Handle<art::mirror::Class> h_klass(hs.NewHandle(obj->AsClass()));
std::string err_unused;
*is_redefinable =
Redefiner::GetClassRedefinitionError<kType>(h_klass, &err_unused) != ERR(UNMODIFIABLE_CLASS)
? JNI_TRUE
: JNI_FALSE;
return OK;
}
jvmtiError
Redefiner::IsStructurallyModifiableClass(jvmtiEnv* env, jclass klass, jboolean* is_redefinable) {
return Redefiner::IsModifiableClassGeneric<RedefinitionType::kStructural>(
env, klass, is_redefinable);
}
jvmtiError Redefiner::IsModifiableClass(jvmtiEnv* env, jclass klass, jboolean* is_redefinable) {
return Redefiner::IsModifiableClassGeneric<RedefinitionType::kNormal>(env, klass, is_redefinable);
}
template <RedefinitionType kType>
jvmtiError Redefiner::GetClassRedefinitionError(jclass klass, /*out*/ std::string* error_msg) {
art::Thread* self = art::Thread::Current();
art::ScopedObjectAccess soa(self);
art::StackHandleScope<1> hs(self);
art::ObjPtr<art::mirror::Object> obj(self->DecodeJObject(klass));
if (obj.IsNull() || !obj->IsClass()) {
return ERR(INVALID_CLASS);
}
art::Handle<art::mirror::Class> h_klass(hs.NewHandle(obj->AsClass()));
return Redefiner::GetClassRedefinitionError<kType>(h_klass, error_msg);
}
template <RedefinitionType kType>
jvmtiError Redefiner::GetClassRedefinitionError(art::Handle<art::mirror::Class> klass,
/*out*/ std::string* error_msg) {
art::Thread* self = art::Thread::Current();
if (!klass->IsResolved()) {
// It's only a problem to try to retransform/redefine a unprepared class if it's happening on
// the same thread as the class-linking process. If it's on another thread we will be able to
// wait for the preparation to finish and continue from there.
if (klass->GetLockOwnerThreadId() == self->GetThreadId()) {
*error_msg = "Modification of class " + klass->PrettyClass() +
" from within the classes ClassLoad callback is not supported to prevent deadlocks." +
" Please use ClassFileLoadHook directly instead.";
return ERR(INTERNAL);
} else {
LOG(WARNING) << klass->PrettyClass() << " is not yet resolved. Attempting to transform "
<< "it could cause arbitrary length waits as the class is being resolved.";
}
}
if (klass->IsPrimitive()) {
*error_msg = "Modification of primitive classes is not supported";
return ERR(UNMODIFIABLE_CLASS);
} else if (klass->IsInterface()) {
*error_msg = "Modification of Interface classes is currently not supported";
return ERR(UNMODIFIABLE_CLASS);
} else if (klass->IsStringClass()) {
*error_msg = "Modification of String class is not supported";
return ERR(UNMODIFIABLE_CLASS);
} else if (klass->IsArrayClass()) {
*error_msg = "Modification of Array classes is not supported";
return ERR(UNMODIFIABLE_CLASS);
} else if (klass->IsProxyClass()) {
*error_msg = "Modification of proxy classes is not supported";
return ERR(UNMODIFIABLE_CLASS);
}
for (jclass c : art::NonDebuggableClasses::GetNonDebuggableClasses()) {
if (klass.Get() == self->DecodeJObject(c)->AsClass()) {
*error_msg = "Class might have stack frames that cannot be made obsolete";
return ERR(UNMODIFIABLE_CLASS);
}
}
if (kType == RedefinitionType::kStructural) {
// Class initialization interacts really badly with structural redefinition since we need to
// make the old class obsolete. We currently just blanket don't allow it.
// TODO It might be nice to allow this at some point.
if (klass->IsInitializing() &&
!klass->IsInitialized() &&
klass->GetClinitThreadId() == self->GetTid()) {
// We are in the class-init running on this thread.
*error_msg = "Modification of class " + klass->PrettyClass() + " during class" +
" initialization is not allowed.";
return ERR(INTERNAL);
}
if (!art::Runtime::Current()->GetClassLinker()->EnsureInitialized(
self, klass, /*can_init_fields=*/true, /*can_init_parents=*/true)) {
self->AssertPendingException();
*error_msg = "Class " + klass->PrettyClass() + " failed initialization. Structural" +
" redefinition of erroneous classes is not allowed. Failure was: " +
self->GetException()->Dump();
self->ClearException();
return ERR(INVALID_CLASS);
}
if (klass->IsMirrored()) {
std::string pc(klass->PrettyClass());
*error_msg = StringPrintf("Class %s is a mirror class and cannot be structurally redefined.",
pc.c_str());
return ERR(UNMODIFIABLE_CLASS);
}
// Check Thread specifically since it's not a root but too many things reach into it with Unsafe
// too allow structural redefinition.
if (klass->IsAssignableFrom(
self->DecodeJObject(art::WellKnownClasses::java_lang_Thread)->AsClass())) {
*error_msg =
"java.lang.Thread has fields accessed using sun.misc.unsafe directly. It is not "
"safe to structurally redefine it.";
return ERR(UNMODIFIABLE_CLASS);
}
// Check for already existing non-static fields/methods.
// TODO Remove this once we support generic method/field addition.
if (!klass->IsFinal()) {
bool non_static_method = false;
klass->VisitMethods([&](art::ArtMethod* m) REQUIRES_SHARED(art::Locks::mutator_lock_) {
// Since direct-methods (ie privates + <init> are not in any vtable/iftable we can update
// them).
if (!m->IsDirect()) {
non_static_method = true;
*error_msg = StringPrintf("%s has a non-direct function %s",
klass->PrettyClass().c_str(),
m->PrettyMethod().c_str());
}
}, art::kRuntimePointerSize);
if (non_static_method) {
return ERR(UNMODIFIABLE_CLASS);
}
bool non_static_field = false;
klass->VisitFields([&](art::ArtField* f) REQUIRES_SHARED(art::Locks::mutator_lock_) {
if (!f->IsStatic()) {
non_static_field = true;
*error_msg = StringPrintf("%s has a non-static field %s",
klass->PrettyClass().c_str(),
f->PrettyField().c_str());
}
});
if (non_static_field) {
return ERR(UNMODIFIABLE_CLASS);
}
}
// Check for fields/methods which were returned before moving to index jni id type.
// TODO We might want to rework how this is done. Once full redefinition is implemented we will
// need to check any subtypes too.
art::ObjPtr<art::mirror::ClassExt> ext(klass->GetExtData());
if (!ext.IsNull()) {
if (ext->HasInstanceFieldPointerIdMarker() ||
ext->HasMethodPointerIdMarker() ||
ext->HasStaticFieldPointerIdMarker()) {
return ERR(UNMODIFIABLE_CLASS);
}
}
}
return OK;
}
template jvmtiError Redefiner::GetClassRedefinitionError<RedefinitionType::kNormal>(
art::Handle<art::mirror::Class> klass, /*out*/ std::string* error_msg);
template jvmtiError Redefiner::GetClassRedefinitionError<RedefinitionType::kStructural>(
art::Handle<art::mirror::Class> klass, /*out*/ std::string* error_msg);
// Moves dex data to an anonymous, read-only mmap'd region.
art::MemMap Redefiner::MoveDataToMemMap(const std::string& original_location,
art::ArrayRef<const unsigned char> data,
std::string* error_msg) {
art::MemMap map = art::MemMap::MapAnonymous(
StringPrintf("%s-transformed", original_location.c_str()).c_str(),
data.size(),
PROT_READ|PROT_WRITE,
/*low_4gb=*/ false,
error_msg);
if (LIKELY(map.IsValid())) {
memcpy(map.Begin(), data.data(), data.size());
// Make the dex files mmap read only. This matches how other DexFiles are mmaped and prevents
// programs from corrupting it.
map.Protect(PROT_READ);
}
return map;
}
Redefiner::ClassRedefinition::ClassRedefinition(
Redefiner* driver,
jclass klass,
const art::DexFile* redefined_dex_file,
const char* class_sig,
art::ArrayRef<const unsigned char> orig_dex_file) :
driver_(driver),
klass_(klass),
dex_file_(redefined_dex_file),
class_sig_(class_sig),
original_dex_file_(orig_dex_file) {
GetMirrorClass()->MonitorEnter(driver_->self_);
}
Redefiner::ClassRedefinition::~ClassRedefinition() {
if (driver_ != nullptr) {
GetMirrorClass()->MonitorExit(driver_->self_);
}
}
template<RedefinitionType kType>
jvmtiError Redefiner::RedefineClassesGeneric(jvmtiEnv* jenv,
jint class_count,
const jvmtiClassDefinition* definitions) {
art::Runtime* runtime = art::Runtime::Current();
art::Thread* self = art::Thread::Current();
ArtJvmTiEnv* env = ArtJvmTiEnv::AsArtJvmTiEnv(jenv);
if (env == nullptr) {
JVMTI_LOG(WARNING, env) << "FAILURE TO REDEFINE env was null!";
return ERR(INVALID_ENVIRONMENT);
} else if (class_count < 0) {
JVMTI_LOG(WARNING, env) << "FAILURE TO REDEFINE class_count was less then 0";
return ERR(ILLEGAL_ARGUMENT);
} else if (class_count == 0) {
// We don't actually need to do anything. Just return OK.
return OK;
} else if (definitions == nullptr) {
JVMTI_LOG(WARNING, env) << "FAILURE TO REDEFINE null definitions!";
return ERR(NULL_POINTER);
}
std::string error_msg;
std::vector<ArtClassDefinition> def_vector;
def_vector.reserve(class_count);
for (jint i = 0; i < class_count; i++) {
jvmtiError res = Redefiner::GetClassRedefinitionError<RedefinitionType::kNormal>(
definitions[i].klass, &error_msg);
if (res != OK) {
JVMTI_LOG(WARNING, env) << "FAILURE TO REDEFINE " << error_msg;
return res;
}
ArtClassDefinition def;
res = def.Init(self, definitions[i]);
if (res != OK) {
JVMTI_LOG(WARNING, env) << "FAILURE TO REDEFINE bad definition " << i;
return res;
}
def_vector.push_back(std::move(def));
}
// Call all the transformation events.
Transformer::RetransformClassesDirect<kType>(self, &def_vector);
if (kType == RedefinitionType::kStructural) {
Transformer::RetransformClassesDirect<RedefinitionType::kNormal>(self, &def_vector);
}
jvmtiError res = RedefineClassesDirect(env, runtime, self, def_vector, kType, &error_msg);
if (res != OK) {
JVMTI_LOG(WARNING, env) << "FAILURE TO REDEFINE " << error_msg;
}
return res;
}
jvmtiError Redefiner::StructurallyRedefineClasses(jvmtiEnv* jenv,
jint class_count,
const jvmtiClassDefinition* definitions) {
ArtJvmTiEnv* art_env = ArtJvmTiEnv::AsArtJvmTiEnv(jenv);
if (art_env == nullptr) {
return ERR(INVALID_ENVIRONMENT);
} else if (art_env->capabilities.can_redefine_classes != 1) {
return ERR(MUST_POSSESS_CAPABILITY);
}
return RedefineClassesGeneric<RedefinitionType::kStructural>(jenv, class_count, definitions);
}
jvmtiError Redefiner::RedefineClasses(jvmtiEnv* jenv,
jint class_count,
const jvmtiClassDefinition* definitions) {
return RedefineClassesGeneric<RedefinitionType::kNormal>(jenv, class_count, definitions);
}
jvmtiError Redefiner::StructurallyRedefineClassDirect(jvmtiEnv* env,
jclass klass,
const unsigned char* data,
jint data_size) {
if (env == nullptr) {
return ERR(INVALID_ENVIRONMENT);
} else if (ArtJvmTiEnv::AsArtJvmTiEnv(env)->capabilities.can_redefine_classes != 1) {
JVMTI_LOG(INFO, env) << "Does not have can_redefine_classes cap!";
return ERR(MUST_POSSESS_CAPABILITY);
}
std::vector<ArtClassDefinition> acds;
ArtClassDefinition acd;
jvmtiError err = acd.Init(
art::Thread::Current(),
jvmtiClassDefinition{ .klass = klass, .class_byte_count = data_size, .class_bytes = data });
if (err != OK) {
return err;
}
acds.push_back(std::move(acd));
std::string err_msg;
err = RedefineClassesDirect(ArtJvmTiEnv::AsArtJvmTiEnv(env),
art::Runtime::Current(),
art::Thread::Current(),
acds,
RedefinitionType::kStructural,
&err_msg);
if (err != OK) {
JVMTI_LOG(WARNING, env) << "Failed structural redefinition: " << err_msg;
}
return err;
}
jvmtiError Redefiner::RedefineClassesDirect(ArtJvmTiEnv* env,
art::Runtime* runtime,
art::Thread* self,
const std::vector<ArtClassDefinition>& definitions,
RedefinitionType type,
std::string* error_msg) {
DCHECK(env != nullptr);
if (definitions.size() == 0) {
// We don't actually need to do anything. Just return OK.
return OK;
}
// We need to fiddle with the verification class flags. To do this we need to make sure there are
// no concurrent redefinitions of the same class at the same time. For simplicity and because
// this is not expected to be a common occurrence we will just wrap the whole thing in a TOP-level
// lock.
// Stop JIT for the duration of this redefine since the JIT might concurrently compile a method we
// are going to redefine.
// TODO We should prevent user-code suspensions to make sure this isn't held for too long.
art::jit::ScopedJitSuspend suspend_jit;
// Get shared mutator lock so we can lock all the classes.
art::ScopedObjectAccess soa(self);
Redefiner r(env, runtime, self, type, error_msg);
for (const ArtClassDefinition& def : definitions) {
// Only try to transform classes that have been modified.
if (def.IsModified()) {
jvmtiError res = r.AddRedefinition(env, def);
if (res != OK) {
return res;
}
}
}
return r.Run();
}
jvmtiError Redefiner::AddRedefinition(ArtJvmTiEnv* env, const ArtClassDefinition& def) {
std::string original_dex_location;
jvmtiError ret = OK;
if ((ret = GetClassLocation(env, def.GetClass(), &original_dex_location))) {
*error_msg_ = "Unable to get original dex file location!";
return ret;
}
char* generic_ptr_unused = nullptr;
char* signature_ptr = nullptr;
if ((ret = env->GetClassSignature(def.GetClass(), &signature_ptr, &generic_ptr_unused)) != OK) {
*error_msg_ = "Unable to get class signature!";
return ret;
}
JvmtiUniquePtr<char> generic_unique_ptr(MakeJvmtiUniquePtr(env, generic_ptr_unused));
JvmtiUniquePtr<char> signature_unique_ptr(MakeJvmtiUniquePtr(env, signature_ptr));
art::MemMap map = MoveDataToMemMap(original_dex_location, def.GetDexData(), error_msg_);
std::ostringstream os;
if (!map.IsValid()) {
os << "Failed to create anonymous mmap for modified dex file of class " << def.GetName()
<< "in dex file " << original_dex_location << " because: " << *error_msg_;
*error_msg_ = os.str();
return ERR(OUT_OF_MEMORY);
}
if (map.Size() < sizeof(art::DexFile::Header)) {
*error_msg_ = "Could not read dex file header because dex_data was too short";
return ERR(INVALID_CLASS_FORMAT);
}
std::string name = map.GetName();
uint32_t checksum = reinterpret_cast<const art::DexFile::Header*>(map.Begin())->checksum_;
const art::ArtDexFileLoader dex_file_loader;
std::unique_ptr<const art::DexFile> dex_file(dex_file_loader.Open(name,
checksum,
std::move(map),
/*verify=*/true,
/*verify_checksum=*/true,
error_msg_));
if (dex_file.get() == nullptr) {
os << "Unable to load modified dex file for " << def.GetName() << ": " << *error_msg_;
*error_msg_ = os.str();
return ERR(INVALID_CLASS_FORMAT);
}
redefinitions_.push_back(
Redefiner::ClassRedefinition(this,
def.GetClass(),
dex_file.release(),
signature_ptr,
def.GetNewOriginalDexFile()));
return OK;
}
art::ObjPtr<art::mirror::Class> Redefiner::ClassRedefinition::GetMirrorClass() {
return driver_->self_->DecodeJObject(klass_)->AsClass();
}
art::ObjPtr<art::mirror::ClassLoader> Redefiner::ClassRedefinition::GetClassLoader() {
return GetMirrorClass()->GetClassLoader();
}
art::mirror::DexCache* Redefiner::ClassRedefinition::CreateNewDexCache(
art::Handle<art::mirror::ClassLoader> loader) {
art::StackHandleScope<2> hs(driver_->self_);
art::ClassLinker* cl = driver_->runtime_->GetClassLinker();
art::Handle<art::mirror::DexCache> cache(hs.NewHandle(
art::ObjPtr<art::mirror::DexCache>::DownCast(
art::GetClassRoot<art::mirror::DexCache>(cl)->AllocObject(driver_->self_))));
if (cache.IsNull()) {
driver_->self_->AssertPendingOOMException();
return nullptr;
}
art::Handle<art::mirror::String> location(hs.NewHandle(
cl->GetInternTable()->InternStrong(dex_file_->GetLocation().c_str())));
if (location.IsNull()) {
driver_->self_->AssertPendingOOMException();
return nullptr;
}
art::WriterMutexLock mu(driver_->self_, *art::Locks::dex_lock_);
art::mirror::DexCache::InitializeDexCache(driver_->self_,
cache.Get(),
location.Get(),
dex_file_.get(),
loader.IsNull() ? driver_->runtime_->GetLinearAlloc()
: loader->GetAllocator(),
art::kRuntimePointerSize);
return cache.Get();
}
void Redefiner::RecordFailure(jvmtiError result,
const std::string& class_sig,
const std::string& error_msg) {
*error_msg_ = StringPrintf("Unable to perform redefinition of '%s': %s",
class_sig.c_str(),
error_msg.c_str());
result_ = result;
}
art::mirror::Object* Redefiner::ClassRedefinition::AllocateOrGetOriginalDexFile() {
// If we have been specifically given a new set of bytes use that
if (original_dex_file_.size() != 0) {
return art::mirror::ByteArray::AllocateAndFill(
driver_->self_,
reinterpret_cast<const signed char*>(original_dex_file_.data()),
original_dex_file_.size()).Ptr();
}
// See if we already have one set.
art::ObjPtr<art::mirror::ClassExt> ext(GetMirrorClass()->GetExtData());
if (!ext.IsNull()) {
art::ObjPtr<art::mirror::Object> old_original_dex_file(ext->GetOriginalDexFile());
if (!old_original_dex_file.IsNull()) {
// We do. Use it.
return old_original_dex_file.Ptr();
}
}
// return the current dex_cache which has the dex file in it.
art::ObjPtr<art::mirror::DexCache> current_dex_cache(GetMirrorClass()->GetDexCache());
// TODO Handle this or make it so it cannot happen.
if (current_dex_cache->GetDexFile()->NumClassDefs() != 1) {
LOG(WARNING) << "Current dex file has more than one class in it. Calling RetransformClasses "
<< "on this class might fail if no transformations are applied to it!";
}
return current_dex_cache.Ptr();
}
struct CallbackCtx {
ObsoleteMap* obsolete_map;
art::LinearAlloc* allocator;
std::unordered_set<art::ArtMethod*> obsolete_methods;
explicit CallbackCtx(ObsoleteMap* map, art::LinearAlloc* alloc)
: obsolete_map(map), allocator(alloc) {}
};
void DoAllocateObsoleteMethodsCallback(art::Thread* t, void* vdata) NO_THREAD_SAFETY_ANALYSIS {
CallbackCtx* data = reinterpret_cast<CallbackCtx*>(vdata);
ObsoleteMethodStackVisitor::UpdateObsoleteFrames(t,
data->allocator,
data->obsolete_methods,
data->obsolete_map);
}
// This creates any ArtMethod* structures needed for obsolete methods and ensures that the stack is
// updated so they will be run.
// TODO Rewrite so we can do this only once regardless of how many redefinitions there are.
void Redefiner::ClassRedefinition::FindAndAllocateObsoleteMethods(
art::ObjPtr<art::mirror::Class> art_klass) {
DCHECK(!IsStructuralRedefinition());
art::ScopedAssertNoThreadSuspension ns("No thread suspension during thread stack walking");
art::ObjPtr<art::mirror::ClassExt> ext = art_klass->GetExtData();
CHECK(ext->GetObsoleteMethods() != nullptr);
art::ClassLinker* linker = driver_->runtime_->GetClassLinker();
// This holds pointers to the obsolete methods map fields which are updated as needed.
ObsoleteMap map(ext->GetObsoleteMethods(), ext->GetObsoleteDexCaches(), art_klass->GetDexCache());
CallbackCtx ctx(&map, linker->GetAllocatorForClassLoader(art_klass->GetClassLoader()));
// Add all the declared methods to the map
for (auto& m : art_klass->GetDeclaredMethods(art::kRuntimePointerSize)) {
if (m.IsIntrinsic()) {
LOG(WARNING) << "Redefining intrinsic method " << m.PrettyMethod() << ". This may cause the "
<< "unexpected use of the original definition of " << m.PrettyMethod() << "in "
<< "methods that have already been compiled.";
}
// It is possible to simply filter out some methods where they cannot really become obsolete,
// such as native methods and keep their original (possibly optimized) implementations. We don't
// do this, however, since we would need to mark these functions (still in the classes
// declared_methods array) as obsolete so we will find the correct dex file to get meta-data
// from (for example about stack-frame size). Furthermore we would be unable to get some useful
// error checking from the interpreter which ensure we don't try to start executing obsolete
// methods.
ctx.obsolete_methods.insert(&m);
}
{
art::MutexLock mu(driver_->self_, *art::Locks::thread_list_lock_);
art::ThreadList* list = art::Runtime::Current()->GetThreadList();
list->ForEach(DoAllocateObsoleteMethodsCallback, static_cast<void*>(&ctx));
// After we've done walking all threads' stacks and updating method pointers on them,
// update JIT data structures (used by the stack walk above) to point to the new methods.
art::jit::Jit* jit = art::Runtime::Current()->GetJit();
if (jit != nullptr) {
for (const ObsoleteMap::ObsoleteMethodPair& it : *ctx.obsolete_map) {
// Notify the JIT we are making this obsolete method. It will update the jit's internal
// structures to keep track of the new obsolete method.
jit->GetCodeCache()->MoveObsoleteMethod(it.old_method, it.obsolete_method);
}
}
}
}
namespace {
template <typename T> struct SignatureType {};
template <> struct SignatureType<art::ArtField> { using type = std::string_view; };
template <> struct SignatureType<art::ArtMethod> { using type = art::Signature; };
template <typename T> struct NameAndSignature {
public:
using SigType = typename SignatureType<T>::type;
NameAndSignature(const art::DexFile* dex_file, uint32_t id);
NameAndSignature(const std::string_view& name, const SigType& sig) : name_(name), sig_(sig) {}
bool operator==(const NameAndSignature<T>& o) {
return name_ == o.name_ && sig_ == o.sig_;
}
std::ostream& dump(std::ostream& os) const {
return os << "'" << name_ << "' (sig: " << sig_ << ")";
}
std::string ToString() const {
std::ostringstream os;
os << *this;
return os.str();
}
std::string_view name_;
SigType sig_;
};
template <typename T>
std::ostream& operator<<(std::ostream& os, const NameAndSignature<T>& nas) {
return nas.dump(os);
}
using FieldNameAndSignature = NameAndSignature<art::ArtField>;
template <>
FieldNameAndSignature::NameAndSignature(const art::DexFile* dex_file, uint32_t id)
: FieldNameAndSignature(dex_file->GetFieldName(dex_file->GetFieldId(id)),
dex_file->GetFieldTypeDescriptor(dex_file->GetFieldId(id))) {}
using MethodNameAndSignature = NameAndSignature<art::ArtMethod>;
template <>
MethodNameAndSignature::NameAndSignature(const art::DexFile* dex_file, uint32_t id)
: MethodNameAndSignature(dex_file->GetMethodName(dex_file->GetMethodId(id)),
dex_file->GetMethodSignature(dex_file->GetMethodId(id))) {}
} // namespace
void Redefiner::ClassRedefinition::RecordNewMethodAdded() {
DCHECK(driver_->IsStructuralRedefinition());
added_methods_ = true;
}
void Redefiner::ClassRedefinition::RecordNewFieldAdded() {
DCHECK(driver_->IsStructuralRedefinition());
added_fields_ = true;
}
bool Redefiner::ClassRedefinition::CheckMethods() {
art::StackHandleScope<1> hs(driver_->self_);
art::Handle<art::mirror::Class> h_klass(hs.NewHandle(GetMirrorClass()));
DCHECK_EQ(dex_file_->NumClassDefs(), 1u);
// Make sure we have the same number of methods (or the same or greater if we're structural).
art::ClassAccessor accessor(*dex_file_, dex_file_->GetClassDef(0));
uint32_t num_new_method = accessor.NumMethods();
uint32_t num_old_method = h_klass->GetDeclaredMethodsSlice(art::kRuntimePointerSize).size();
const bool is_structural = driver_->IsStructuralRedefinition();
if (!is_structural && num_new_method != num_old_method) {
bool bigger = num_new_method > num_old_method;
RecordFailure(bigger ? ERR(UNSUPPORTED_REDEFINITION_METHOD_ADDED)
: ERR(UNSUPPORTED_REDEFINITION_METHOD_DELETED),
StringPrintf("Total number of declared methods changed from %d to %d",
num_old_method,
num_new_method));
return false;
}
// Skip all of the fields. We should have already checked this.
// Check each of the methods. NB we don't need to specifically check for removals since the 2 dex
// files have the same number of methods, which means there must be an equal amount of additions
// and removals. We should have already checked the fields.
const art::DexFile& old_dex_file = h_klass->GetDexFile();
art::ClassAccessor old_accessor(old_dex_file, *h_klass->GetClassDef());
// We need this to check for methods going missing in structural cases.
std::vector<bool> seen_old_methods(
(kCheckAllMethodsSeenOnce || is_structural) ? old_accessor.NumMethods() : 0, false);
const auto old_methods = old_accessor.GetMethods();
for (const art::ClassAccessor::Method& new_method : accessor.GetMethods()) {
// Get the data on the method we are searching for
MethodNameAndSignature new_method_id(dex_file_.get(), new_method.GetIndex());
const auto old_iter =
std::find_if(old_methods.cbegin(), old_methods.cend(), [&](const auto& current_old_method) {
MethodNameAndSignature old_method_id(&old_dex_file, current_old_method.GetIndex());
return old_method_id == new_method_id;
});
if (!new_method.IsStaticOrDirect()) {
RecordHasVirtualMembers();
}
if (old_iter == old_methods.cend()) {
// TODO Support adding non-static methods.
if (is_structural && (new_method.IsStaticOrDirect() || h_klass->IsFinal())) {
RecordNewMethodAdded();
} else {
RecordFailure(
ERR(UNSUPPORTED_REDEFINITION_METHOD_ADDED),
StringPrintf("Unknown virtual method %s was added!", new_method_id.ToString().c_str()));
return false;
}
} else if (new_method.GetAccessFlags() != old_iter->GetAccessFlags()) {
RecordFailure(
ERR(UNSUPPORTED_REDEFINITION_METHOD_MODIFIERS_CHANGED),
StringPrintf("method %s had different access flags", new_method_id.ToString().c_str()));
return false;
} else if (kCheckAllMethodsSeenOnce || is_structural) {
// We only need this if we are structural.
size_t off = std::distance(old_methods.cbegin(), old_iter);
DCHECK(!seen_old_methods[off])
<< "field at " << off << "("
<< MethodNameAndSignature(&old_dex_file, old_iter->GetIndex()) << ") already seen?";
seen_old_methods[off] = true;
}
}
if ((kCheckAllMethodsSeenOnce || is_structural) &&
!std::all_of(seen_old_methods.cbegin(), seen_old_methods.cend(), [](auto x) { return x; })) {
DCHECK(is_structural) << "We should have hit an earlier failure before getting here!";
auto first_fail =
std::find_if(seen_old_methods.cbegin(), seen_old_methods.cend(), [](auto x) { return !x; });
auto off = std::distance(seen_old_methods.cbegin(), first_fail);
auto fail = old_methods.cbegin();
std::advance(fail, off);
RecordFailure(
ERR(UNSUPPORTED_REDEFINITION_METHOD_DELETED),
StringPrintf("Method %s missing!",
FieldNameAndSignature(&old_dex_file, fail->GetIndex()).ToString().c_str()));
return false;
}
return true;
}
bool Redefiner::ClassRedefinition::CheckFields() {
art::StackHandleScope<1> hs(driver_->self_);
art::Handle<art::mirror::Class> h_klass(hs.NewHandle(GetMirrorClass()));
DCHECK_EQ(dex_file_->NumClassDefs(), 1u);
art::ClassAccessor new_accessor(*dex_file_, dex_file_->GetClassDef(0));
const art::DexFile& old_dex_file = h_klass->GetDexFile();
art::ClassAccessor old_accessor(old_dex_file, *h_klass->GetClassDef());
// Instance and static fields can be differentiated by their flags so no need to check them
// separately.
std::vector<bool> seen_old_fields(old_accessor.NumFields(), false);
const auto old_fields = old_accessor.GetFields();
for (const art::ClassAccessor::Field& new_field : new_accessor.GetFields()) {
// Get the data on the method we are searching for
FieldNameAndSignature new_field_id(dex_file_.get(), new_field.GetIndex());
const auto old_iter =
std::find_if(old_fields.cbegin(), old_fields.cend(), [&](const auto& old_iter) {
FieldNameAndSignature old_field_id(&old_dex_file, old_iter.GetIndex());
return old_field_id == new_field_id;
});
if (!new_field.IsStatic()) {
RecordHasVirtualMembers();
}
if (old_iter == old_fields.cend()) {
// TODO Support adding non-static fields.
if (driver_->IsStructuralRedefinition() && (new_field.IsStatic() || h_klass->IsFinal())) {
RecordNewFieldAdded();
} else {
RecordFailure(ERR(UNSUPPORTED_REDEFINITION_SCHEMA_CHANGED),
StringPrintf("Unknown field %s added!", new_field_id.ToString().c_str()));
return false;
}
} else if (new_field.GetAccessFlags() != old_iter->GetAccessFlags()) {
RecordFailure(
ERR(UNSUPPORTED_REDEFINITION_SCHEMA_CHANGED),
StringPrintf("Field %s had different access flags", new_field_id.ToString().c_str()));
return false;
} else {
size_t off = std::distance(old_fields.cbegin(), old_iter);
DCHECK(!seen_old_fields[off])
<< "field at " << off << "(" << FieldNameAndSignature(&old_dex_file, old_iter->GetIndex())
<< ") already seen?";
seen_old_fields[off] = true;
}
}
if (!std::all_of(seen_old_fields.cbegin(), seen_old_fields.cend(), [](auto x) { return x; })) {
auto first_fail =
std::find_if(seen_old_fields.cbegin(), seen_old_fields.cend(), [](auto x) { return !x; });
auto off = std::distance(seen_old_fields.cbegin(), first_fail);
auto fail = old_fields.cbegin();
std::advance(fail, off);
RecordFailure(
ERR(UNSUPPORTED_REDEFINITION_SCHEMA_CHANGED),
StringPrintf("Field %s is missing!",
FieldNameAndSignature(&old_dex_file, fail->GetIndex()).ToString().c_str()));
return false;
}
return true;
}
bool Redefiner::ClassRedefinition::CheckClass() {
art::StackHandleScope<1> hs(driver_->self_);
// Easy check that only 1 class def is present.
if (dex_file_->NumClassDefs() != 1) {
RecordFailure(ERR(ILLEGAL_ARGUMENT),
StringPrintf("Expected 1 class def in dex file but found %d",
dex_file_->NumClassDefs()));
return false;
}
// Get the ClassDef from the new DexFile.
// Since the dex file has only a single class def the index is always 0.
const art::dex::ClassDef& def = dex_file_->GetClassDef(0);
// Get the class as it is now.
art::Handle<art::mirror::Class> current_class(hs.NewHandle(GetMirrorClass()));
// Check the access flags didn't change.
if (def.GetJavaAccessFlags() != (current_class->GetAccessFlags() & art::kAccValidClassFlags)) {
RecordFailure(ERR(UNSUPPORTED_REDEFINITION_CLASS_MODIFIERS_CHANGED),
"Cannot change modifiers of class by redefinition");
return false;
}
// Check class name.
// These should have been checked by the dexfile verifier on load.
DCHECK_NE(def.class_idx_, art::dex::TypeIndex::Invalid()) << "Invalid type index";
const char* descriptor = dex_file_->StringByTypeIdx(def.class_idx_);
DCHECK(descriptor != nullptr) << "Invalid dex file structure!";
if (!current_class->DescriptorEquals(descriptor)) {
std::string storage;
RecordFailure(ERR(NAMES_DONT_MATCH),
StringPrintf("expected file to contain class called '%s' but found '%s'!",
current_class->GetDescriptor(&storage),
descriptor));
return false;
}
if (current_class->IsObjectClass()) {
if (def.superclass_idx_ != art::dex::TypeIndex::Invalid()) {
RecordFailure(ERR(UNSUPPORTED_REDEFINITION_HIERARCHY_CHANGED), "Superclass added!");
return false;
}
} else {
const char* super_descriptor = dex_file_->StringByTypeIdx(def.superclass_idx_);
DCHECK(descriptor != nullptr) << "Invalid dex file structure!";
if (!current_class->GetSuperClass()->DescriptorEquals(super_descriptor)) {
RecordFailure(ERR(UNSUPPORTED_REDEFINITION_HIERARCHY_CHANGED), "Superclass changed");
return false;
}
}
const art::dex::TypeList* interfaces = dex_file_->GetInterfacesList(def);
if (interfaces == nullptr) {
if (current_class->NumDirectInterfaces() != 0) {
// TODO Support this for kStructural.
RecordFailure(ERR(UNSUPPORTED_REDEFINITION_HIERARCHY_CHANGED), "Interfaces added");
return false;
}
} else {
DCHECK(!current_class->IsProxyClass());
const art::dex::TypeList* current_interfaces = current_class->GetInterfaceTypeList();
if (current_interfaces == nullptr || current_interfaces->Size() != interfaces->Size()) {
// TODO Support this for kStructural.
RecordFailure(ERR(UNSUPPORTED_REDEFINITION_HIERARCHY_CHANGED), "Interfaces added or removed");
return false;
}
// The order of interfaces is (barely) meaningful so we error if it changes.
const art::DexFile& orig_dex_file = current_class->GetDexFile();
for (uint32_t i = 0; i < interfaces->Size(); i++) {
if (strcmp(
dex_file_->StringByTypeIdx(interfaces->GetTypeItem(i).type_idx_),
orig_dex_file.StringByTypeIdx(current_interfaces->GetTypeItem(i).type_idx_)) != 0) {
RecordFailure(ERR(UNSUPPORTED_REDEFINITION_HIERARCHY_CHANGED),
"Interfaces changed or re-ordered");
return false;
}
}
}
return true;
}
bool Redefiner::ClassRedefinition::CheckRedefinable() {
std::string err;
art::StackHandleScope<1> hs(driver_->self_);
art::Handle<art::mirror::Class> h_klass(hs.NewHandle(GetMirrorClass()));
jvmtiError res;
if (driver_->type_ == RedefinitionType::kStructural && this->IsStructuralRedefinition()) {
res = Redefiner::GetClassRedefinitionError<RedefinitionType::kStructural>(h_klass, &err);
if (res == OK && HasVirtualMembers() && h_klass->IsFinalizable()) {
res = ERR(INTERNAL);
err = "Cannot redefine finalizable objects at this time.";
}
} else {
res = Redefiner::GetClassRedefinitionError<RedefinitionType::kNormal>(h_klass, &err);
}
if (res != OK) {
RecordFailure(res, err);
return false;
} else {
return true;
}
}
bool Redefiner::ClassRedefinition::CheckRedefinitionIsValid() {
return CheckClass() && CheckFields() && CheckMethods() && CheckRedefinable();
}
class RedefinitionDataIter;
// A wrapper that lets us hold onto the arbitrary sized data needed for redefinitions in a
// reasonably sane way. This adds no fields to the normal ObjectArray. By doing this we can avoid
// having to deal with the fact that we need to hold an arbitrary number of references live.
class RedefinitionDataHolder {
public:
enum DataSlot : int32_t {
kSlotSourceClassLoader = 0,
kSlotJavaDexFile = 1,
kSlotNewDexFileCookie = 2,
kSlotNewDexCache = 3,
kSlotMirrorClass = 4,
kSlotOrigDexFile = 5,
kSlotOldObsoleteMethods = 6,
kSlotOldDexCaches = 7,
kSlotNewClassObject = 8,
kSlotOldInstanceObjects = 9,
kSlotNewInstanceObjects = 10,
// Must be last one.
kNumSlots = 11,
};
// This needs to have a HandleScope passed in that is capable of creating a new Handle without
// overflowing. Only one handle will be created. This object has a lifetime identical to that of
// the passed in handle-scope.
RedefinitionDataHolder(art::StackHandleScope<1>* hs,
art::Runtime* runtime,
art::Thread* self,
std::vector<Redefiner::ClassRedefinition>* redefinitions)
REQUIRES_SHARED(art::Locks::mutator_lock_) :
arr_(hs->NewHandle(art::mirror::ObjectArray<art::mirror::Object>::Alloc(
self,
art::GetClassRoot<art::mirror::ObjectArray<art::mirror::Object>>(runtime->GetClassLinker()),
redefinitions->size() * kNumSlots))),
redefinitions_(redefinitions) {}
bool IsNull() const REQUIRES_SHARED(art::Locks::mutator_lock_) {
return arr_.IsNull();
}
art::ObjPtr<art::mirror::ClassLoader> GetSourceClassLoader(jint klass_index) const
REQUIRES_SHARED(art::Locks::mutator_lock_) {
return art::ObjPtr<art::mirror::ClassLoader>::DownCast(
GetSlot(klass_index, kSlotSourceClassLoader));
}
art::ObjPtr<art::mirror::Object> GetJavaDexFile(jint klass_index) const
REQUIRES_SHARED(art::Locks::mutator_lock_) {
return GetSlot(klass_index, kSlotJavaDexFile);
}
art::ObjPtr<art::mirror::LongArray> GetNewDexFileCookie(jint klass_index) const
REQUIRES_SHARED(art::Locks::mutator_lock_) {
return art::ObjPtr<art::mirror::LongArray>::DownCast(
GetSlot(klass_index, kSlotNewDexFileCookie));
}
art::ObjPtr<art::mirror::DexCache> GetNewDexCache(jint klass_index) const
REQUIRES_SHARED(art::Locks::mutator_lock_) {
return art::ObjPtr<art::mirror::DexCache>::DownCast(GetSlot(klass_index, kSlotNewDexCache));
}
art::ObjPtr<art::mirror::Class> GetMirrorClass(jint klass_index) const
REQUIRES_SHARED(art::Locks::mutator_lock_) {
return art::ObjPtr<art::mirror::Class>::DownCast(GetSlot(klass_index, kSlotMirrorClass));
}
art::ObjPtr<art::mirror::Object> GetOriginalDexFile(jint klass_index) const
REQUIRES_SHARED(art::Locks::mutator_lock_) {
return art::ObjPtr<art::mirror::Object>::DownCast(GetSlot(klass_index, kSlotOrigDexFile));
}
art::ObjPtr<art::mirror::PointerArray> GetOldObsoleteMethods(jint klass_index) const
REQUIRES_SHARED(art::Locks::mutator_lock_) {
return art::ObjPtr<art::mirror::PointerArray>::DownCast(
GetSlot(klass_index, kSlotOldObsoleteMethods));
}
art::ObjPtr<art::mirror::ObjectArray<art::mirror::DexCache>> GetOldDexCaches(
jint klass_index) const REQUIRES_SHARED(art::Locks::mutator_lock_) {
return art::ObjPtr<art::mirror::ObjectArray<art::mirror::DexCache>>::DownCast(
GetSlot(klass_index, kSlotOldDexCaches));
}
art::ObjPtr<art::mirror::Class> GetNewClassObject(jint klass_index) const
REQUIRES_SHARED(art::Locks::mutator_lock_) {
return art::ObjPtr<art::mirror::Class>::DownCast(GetSlot(klass_index, kSlotNewClassObject));
}
art::ObjPtr<art::mirror::ObjectArray<art::mirror::Object>> GetOldInstanceObjects(
jint klass_index) const REQUIRES_SHARED(art::Locks::mutator_lock_) {
return art::ObjPtr<art::mirror::ObjectArray<art::mirror::Object>>::DownCast(
GetSlot(klass_index, kSlotOldInstanceObjects));
}
art::ObjPtr<art::mirror::ObjectArray<art::mirror::Object>> GetNewInstanceObjects(
jint klass_index) const REQUIRES_SHARED(art::Locks::mutator_lock_) {
return art::ObjPtr<art::mirror::ObjectArray<art::mirror::Object>>::DownCast(
GetSlot(klass_index, kSlotNewInstanceObjects));
}
void SetSourceClassLoader(jint klass_index, art::ObjPtr<art::mirror::ClassLoader> loader)
REQUIRES_SHARED(art::Locks::mutator_lock_) {
SetSlot(klass_index, kSlotSourceClassLoader, loader);
}
void SetJavaDexFile(jint klass_index, art::ObjPtr<art::mirror::Object> dexfile)
REQUIRES_SHARED(art::Locks::mutator_lock_) {
SetSlot(klass_index, kSlotJavaDexFile, dexfile);
}
void SetNewDexFileCookie(jint klass_index, art::ObjPtr<art::mirror::LongArray> cookie)
REQUIRES_SHARED(art::Locks::mutator_lock_) {
SetSlot(klass_index, kSlotNewDexFileCookie, cookie);
}
void SetNewDexCache(jint klass_index, art::ObjPtr<art::mirror::DexCache> cache)
REQUIRES_SHARED(art::Locks::mutator_lock_) {
SetSlot(klass_index, kSlotNewDexCache, cache);
}
void SetMirrorClass(jint klass_index, art::ObjPtr<art::mirror::Class> klass)
REQUIRES_SHARED(art::Locks::mutator_lock_) {
SetSlot(klass_index, kSlotMirrorClass, klass);
}
void SetOriginalDexFile(jint klass_index, art::ObjPtr<art::mirror::Object> bytes)
REQUIRES_SHARED(art::Locks::mutator_lock_) {
SetSlot(klass_index, kSlotOrigDexFile, bytes);
}
void SetOldObsoleteMethods(jint klass_index, art::ObjPtr<art::mirror::PointerArray> methods)
REQUIRES_SHARED(art::Locks::mutator_lock_) {
SetSlot(klass_index, kSlotOldObsoleteMethods, methods);
}
void SetOldDexCaches(jint klass_index,
art::ObjPtr<art::mirror::ObjectArray<art::mirror::DexCache>> caches)
REQUIRES_SHARED(art::Locks::mutator_lock_) {
SetSlot(klass_index, kSlotOldDexCaches, caches);
}
void SetNewClassObject(jint klass_index, art::ObjPtr<art::mirror::Class> klass)
REQUIRES_SHARED(art::Locks::mutator_lock_) {
SetSlot(klass_index, kSlotNewClassObject, klass);
}
void SetOldInstanceObjects(jint klass_index,
art::ObjPtr<art::mirror::ObjectArray<art::mirror::Object>> objs)
REQUIRES_SHARED(art::Locks::mutator_lock_) {
SetSlot(klass_index, kSlotOldInstanceObjects, objs);
}
void SetNewInstanceObjects(jint klass_index,
art::ObjPtr<art::mirror::ObjectArray<art::mirror::Object>> objs)
REQUIRES_SHARED(art::Locks::mutator_lock_) {
SetSlot(klass_index, kSlotNewInstanceObjects, objs);
}
int32_t Length() const REQUIRES_SHARED(art::Locks::mutator_lock_) {
return arr_->GetLength() / kNumSlots;
}
std::vector<Redefiner::ClassRedefinition>* GetRedefinitions()
REQUIRES_SHARED(art::Locks::mutator_lock_) {
return redefinitions_;
}
bool operator==(const RedefinitionDataHolder& other) const
REQUIRES_SHARED(art::Locks::mutator_lock_) {
return arr_.Get() == other.arr_.Get();
}
bool operator!=(const RedefinitionDataHolder& other) const
REQUIRES_SHARED(art::Locks::mutator_lock_) {
return !(*this == other);
}
RedefinitionDataIter begin() REQUIRES_SHARED(art::Locks::mutator_lock_);
RedefinitionDataIter end() REQUIRES_SHARED(art::Locks::mutator_lock_);
private:
mutable art::Handle<art::mirror::ObjectArray<art::mirror::Object>> arr_;
std::vector<Redefiner::ClassRedefinition>* redefinitions_;
art::ObjPtr<art::mirror::Object> GetSlot(jint klass_index, DataSlot slot) const
REQUIRES_SHARED(art::Locks::mutator_lock_) {
DCHECK_LT(klass_index, Length());
return arr_->Get((kNumSlots * klass_index) + slot);
}
void SetSlot(jint klass_index,
DataSlot slot,
art::ObjPtr<art::mirror::Object> obj) REQUIRES_SHARED(art::Locks::mutator_lock_) {
DCHECK(!art::Runtime::Current()->IsActiveTransaction());
DCHECK_LT(klass_index, Length());
arr_->Set<false>((kNumSlots * klass_index) + slot, obj);
}
DISALLOW_COPY_AND_ASSIGN(RedefinitionDataHolder);
};
class RedefinitionDataIter {
public:
RedefinitionDataIter(int32_t idx, RedefinitionDataHolder& holder) : idx_(idx), holder_(holder) {}
RedefinitionDataIter(const RedefinitionDataIter&) = default;
RedefinitionDataIter(RedefinitionDataIter&&) = default;
RedefinitionDataIter& operator=(const RedefinitionDataIter&) = default;
RedefinitionDataIter& operator=(RedefinitionDataIter&&) = default;
bool operator==(const RedefinitionDataIter& other) const
REQUIRES_SHARED(art::Locks::mutator_lock_) {
return idx_ == other.idx_ && holder_ == other.holder_;
}
bool operator!=(const RedefinitionDataIter& other) const
REQUIRES_SHARED(art::Locks::mutator_lock_) {
return !(*this == other);
}
RedefinitionDataIter operator++() { // Value after modification.
idx_++;
return *this;
}
RedefinitionDataIter operator++(int) {
RedefinitionDataIter temp = *this;
idx_++;
return temp;
}
RedefinitionDataIter operator+(ssize_t delta) const {
RedefinitionDataIter temp = *this;
temp += delta;
return temp;
}
RedefinitionDataIter& operator+=(ssize_t delta) {
idx_ += delta;
return *this;
}
// Compat for STL iterators.
RedefinitionDataIter& operator*() {
return *this;
}
Redefiner::ClassRedefinition& GetRedefinition() REQUIRES_SHARED(art::Locks::mutator_lock_) {
return (*holder_.GetRedefinitions())[idx_];
}
RedefinitionDataHolder& GetHolder() {
return holder_;
}
art::ObjPtr<art::mirror::ClassLoader> GetSourceClassLoader() const
REQUIRES_SHARED(art::Locks::mutator_lock_) {
return holder_.GetSourceClassLoader(idx_);
}
art::ObjPtr<art::mirror::Object> GetJavaDexFile() const
REQUIRES_SHARED(art::Locks::mutator_lock_) {
return holder_.GetJavaDexFile(idx_);
}
art::ObjPtr<art::mirror::LongArray> GetNewDexFileCookie() const
REQUIRES_SHARED(art::Locks::mutator_lock_) {
return holder_.GetNewDexFileCookie(idx_);
}
art::ObjPtr<art::mirror::DexCache> GetNewDexCache() const
REQUIRES_SHARED(art::Locks::mutator_lock_) {
return holder_.GetNewDexCache(idx_);
}
art::ObjPtr<art::mirror::Class> GetMirrorClass() const
REQUIRES_SHARED(art::Locks::mutator_lock_) {
return holder_.GetMirrorClass(idx_);
}
art::ObjPtr<art::mirror::Object> GetOriginalDexFile() const
REQUIRES_SHARED(art::Locks::mutator_lock_) {
return holder_.GetOriginalDexFile(idx_);
}
art::ObjPtr<art::mirror::PointerArray> GetOldObsoleteMethods() const
REQUIRES_SHARED(art::Locks::mutator_lock_) {
return holder_.GetOldObsoleteMethods(idx_);
}
art::ObjPtr<art::mirror::ObjectArray<art::mirror::DexCache>> GetOldDexCaches() const
REQUIRES_SHARED(art::Locks::mutator_lock_) {
return holder_.GetOldDexCaches(idx_);
}
art::ObjPtr<art::mirror::Class> GetNewClassObject() const
REQUIRES_SHARED(art::Locks::mutator_lock_) {
return holder_.GetNewClassObject(idx_);
}
art::ObjPtr<art::mirror::ObjectArray<art::mirror::Object>> GetOldInstanceObjects() const
REQUIRES_SHARED(art::Locks::mutator_lock_) {
return holder_.GetOldInstanceObjects(idx_);
}
art::ObjPtr<art::mirror::ObjectArray<art::mirror::Object>> GetNewInstanceObjects() const
REQUIRES_SHARED(art::Locks::mutator_lock_) {
return holder_.GetNewInstanceObjects(idx_);
}
int32_t GetIndex() const {
return idx_;
}
void SetSourceClassLoader(art::mirror::ClassLoader* loader)
REQUIRES_SHARED(art::Locks::mutator_lock_) {
holder_.SetSourceClassLoader(idx_, loader);
}
void SetJavaDexFile(art::ObjPtr<art::mirror::Object> dexfile)
REQUIRES_SHARED(art::Locks::mutator_lock_) {
holder_.SetJavaDexFile(idx_, dexfile);
}
void SetNewDexFileCookie(art::ObjPtr<art::mirror::LongArray> cookie)
REQUIRES_SHARED(art::Locks::mutator_lock_) {
holder_.SetNewDexFileCookie(idx_, cookie);
}
void SetNewDexCache(art::ObjPtr<art::mirror::DexCache> cache)
REQUIRES_SHARED(art::Locks::mutator_lock_) {
holder_.SetNewDexCache(idx_, cache);
}
void SetMirrorClass(art::ObjPtr<art::mirror::Class> klass)
REQUIRES_SHARED(art::Locks::mutator_lock_) {
holder_.SetMirrorClass(idx_, klass);
}
void SetOriginalDexFile(art::ObjPtr<art::mirror::Object> bytes)
REQUIRES_SHARED(art::Locks::mutator_lock_) {
holder_.SetOriginalDexFile(idx_, bytes);
}
void SetOldObsoleteMethods(art::ObjPtr<art::mirror::PointerArray> methods)
REQUIRES_SHARED(art::Locks::mutator_lock_) {
holder_.SetOldObsoleteMethods(idx_, methods);
}
void SetOldDexCaches(art::ObjPtr<art::mirror::ObjectArray<art::mirror::DexCache>> caches)
REQUIRES_SHARED(art::Locks::mutator_lock_) {
holder_.SetOldDexCaches(idx_, caches);
}
void SetNewClassObject(art::ObjPtr<art::mirror::Class> klass)
REQUIRES_SHARED(art::Locks::mutator_lock_) {
holder_.SetNewClassObject(idx_, klass);
}
void SetOldInstanceObjects(art::ObjPtr<art::mirror::ObjectArray<art::mirror::Object>> objs)
REQUIRES_SHARED(art::Locks::mutator_lock_) {
holder_.SetOldInstanceObjects(idx_, objs);
}
void SetNewInstanceObjects(art::ObjPtr<art::mirror::ObjectArray<art::mirror::Object>> objs)
REQUIRES_SHARED(art::Locks::mutator_lock_) {
holder_.SetNewInstanceObjects(idx_, objs);
}
private:
int32_t idx_;
RedefinitionDataHolder& holder_;
};
RedefinitionDataIter RedefinitionDataHolder::begin() {
return RedefinitionDataIter(0, *this);
}
RedefinitionDataIter RedefinitionDataHolder::end() {
return RedefinitionDataIter(Length(), *this);
}
bool Redefiner::ClassRedefinition::CheckVerification(const RedefinitionDataIter& iter) {
DCHECK_EQ(dex_file_->NumClassDefs(), 1u);
art::StackHandleScope<2> hs(driver_->self_);
std::string error;
// TODO Make verification log level lower
art::verifier::FailureKind failure =
art::verifier::ClassVerifier::VerifyClass(driver_->self_,
dex_file_.get(),
hs.NewHandle(iter.GetNewDexCache()),
hs.NewHandle(GetClassLoader()),
/*class_def=*/ dex_file_->GetClassDef(0),
/*callbacks=*/ nullptr,
/*allow_soft_failures=*/ true,
/*log_level=*/
art::verifier::HardFailLogMode::kLogWarning,
art::Runtime::Current()->GetTargetSdkVersion(),
&error);
switch (failure) {
case art::verifier::FailureKind::kNoFailure:
// TODO It is possible that by doing redefinition previous NO_COMPILE verification failures
// were fixed. It would be nice to reflect this in the new implementations.
return true;
case art::verifier::FailureKind::kSoftFailure:
// Soft failures might require interpreter on some methods. It won't prevent redefinition but
// it does mean we need to run the verifier again and potentially update method flags after
// performing the swap.
needs_reverify_ = true;
return true;
case art::verifier::FailureKind::kHardFailure: {
RecordFailure(ERR(FAILS_VERIFICATION), "Failed to verify class. Error was: " + error);
return false;
}
}
}
// Looks through the previously allocated cookies to see if we need to update them with another new
// dexfile. This is so that even if multiple classes with the same classloader are redefined at
// once they are all added to the classloader.
bool Redefiner::ClassRedefinition::AllocateAndRememberNewDexFileCookie(
art::Handle<art::mirror::ClassLoader> source_class_loader,
art::Handle<art::mirror::Object> dex_file_obj,
/*out*/RedefinitionDataIter* cur_data) {
art::StackHandleScope<2> hs(driver_->self_);
art::MutableHandle<art::mirror::LongArray> old_cookie(
hs.NewHandle<art::mirror::LongArray>(nullptr));
bool has_older_cookie = false;
// See if we already have a cookie that a previous redefinition got from the same classloader.
for (auto old_data = cur_data->GetHolder().begin(); old_data != *cur_data; ++old_data) {
if (old_data.GetSourceClassLoader() == source_class_loader.Get()) {
// Since every instance of this classloader should have the same cookie associated with it we
// can stop looking here.
has_older_cookie = true;
old_cookie.Assign(old_data.GetNewDexFileCookie());
break;
}
}
if (old_cookie.IsNull()) {
// No older cookie. Get it directly from the dex_file_obj
// We should not have seen this classloader elsewhere.
CHECK(!has_older_cookie);
old_cookie.Assign(ClassLoaderHelper::GetDexFileCookie(dex_file_obj));
}
// Use the old cookie to generate the new one with the new DexFile* added in.
art::Handle<art::mirror::LongArray>
new_cookie(hs.NewHandle(ClassLoaderHelper::AllocateNewDexFileCookie(driver_->self_,
old_cookie,
dex_file_.get())));
// Make sure the allocation worked.
if (new_cookie.IsNull()) {
return false;
}
// Save the cookie.
cur_data->SetNewDexFileCookie(new_cookie.Get());
// If there are other copies of this same classloader we need to make sure that we all have the
// same cookie.
if (has_older_cookie) {
for (auto old_data = cur_data->GetHolder().begin(); old_data != *cur_data; ++old_data) {
// We will let the GC take care of the cookie we allocated for this one.
if (old_data.GetSourceClassLoader() == source_class_loader.Get()) {
old_data.SetNewDexFileCookie(new_cookie.Get());
}
}
}
return true;
}
bool Redefiner::ClassRedefinition::CollectAndCreateNewInstances(
/*out*/ RedefinitionDataIter* cur_data) {
if (!IsStructuralRedefinition()) {
return true;
}
art::VariableSizedHandleScope hs(driver_->self_);
art::Handle<art::mirror::Class> old_klass(hs.NewHandle(cur_data->GetMirrorClass()));
std::vector<art::Handle<art::mirror::Object>> old_instances;
art::gc::Heap* heap = driver_->runtime_->GetHeap();
auto is_instance = [&](art::mirror::Object* obj) REQUIRES_SHARED(art::Locks::mutator_lock_) {
if (HasVirtualMembers()) {
return old_klass->IsAssignableFrom(obj->GetClass());
} else {
// We don't need to deal with objects of subtypes when we don't modify virtuals since the
// vtable + field layout will remain the same.
return old_klass.Get() == obj->GetClass();
}
};
heap->VisitObjects([&](art::mirror::Object* obj) REQUIRES_SHARED(art::Locks::mutator_lock_) {
if (is_instance(obj)) {
CHECK(old_klass.Get() == obj->GetClass()) << "No support for subtypes yet!";
old_instances.push_back(hs.NewHandle(obj));
}
});
VLOG(plugin) << "Collected " << old_instances.size() << " instances to recreate!";
art::Handle<art::mirror::Class> obj_array_class(
hs.NewHandle(art::GetClassRoot<art::mirror::ObjectArray<art::mirror::Object>>(
driver_->runtime_->GetClassLinker())));
art::Handle<art::mirror::ObjectArray<art::mirror::Object>> old_instances_arr(
hs.NewHandle(art::mirror::ObjectArray<art::mirror::Object>::Alloc(
driver_->self_, obj_array_class.Get(), old_instances.size())));
if (old_instances_arr.IsNull()) {
driver_->self_->AssertPendingOOMException();
driver_->self_->ClearException();
RecordFailure(ERR(OUT_OF_MEMORY), "Could not allocate old_instance arrays!");
return false;
}
for (uint32_t i = 0; i < old_instances.size(); ++i) {
old_instances_arr->Set(i, old_instances[i].Get());
}
cur_data->SetOldInstanceObjects(old_instances_arr.Get());
art::Handle<art::mirror::ObjectArray<art::mirror::Object>> new_instances_arr(
hs.NewHandle(art::mirror::ObjectArray<art::mirror::Object>::Alloc(
driver_->self_, obj_array_class.Get(), old_instances.size())));
if (new_instances_arr.IsNull()) {
driver_->self_->AssertPendingOOMException();
driver_->self_->ClearException();
RecordFailure(ERR(OUT_OF_MEMORY), "Could not allocate new_instance arrays!");
return false;
}
art::Handle<art::mirror::Class> new_klass(hs.NewHandle(cur_data->GetNewClassObject()));
for (uint32_t i = 0; i < old_instances.size(); ++i) {
art::ObjPtr<art::mirror::Object> new_instance(new_klass->AllocObject(driver_->self_));
if (new_instance.IsNull()) {
driver_->self_->AssertPendingOOMException();
driver_->self_->ClearException();
std::string msg(
StringPrintf("Could not allocate instance %d of %zu", i, old_instances.size()));
RecordFailure(ERR(OUT_OF_MEMORY), msg);
return false;
}
new_instances_arr->Set(i, new_instance);
}
cur_data->SetNewInstanceObjects(new_instances_arr.Get());
return true;
}
bool Redefiner::ClassRedefinition::FinishRemainingAllocations(
/*out*/RedefinitionDataIter* cur_data) {
art::ScopedObjectAccessUnchecked soa(driver_->self_);
art::StackHandleScope<4> hs(driver_->self_);
cur_data->SetMirrorClass(GetMirrorClass());
// This shouldn't allocate
art::Handle<art::mirror::ClassLoader> loader(hs.NewHandle(GetClassLoader()));
// The bootclasspath is handled specially so it doesn't have a j.l.DexFile.
if (!art::ClassLinker::IsBootClassLoader(soa, loader.Get())) {
cur_data->SetSourceClassLoader(loader.Get());
art::Handle<art::mirror::Object> dex_file_obj(hs.NewHandle(
ClassLoaderHelper::FindSourceDexFileObject(driver_->self_, loader)));
cur_data->SetJavaDexFile(dex_file_obj.Get());
if (dex_file_obj == nullptr) {
RecordFailure(ERR(INTERNAL), "Unable to find dex file!");
return false;
}
// Allocate the new dex file cookie.
if (!AllocateAndRememberNewDexFileCookie(loader, dex_file_obj, cur_data)) {
driver_->self_->AssertPendingOOMException();
driver_->self_->ClearException();
RecordFailure(ERR(OUT_OF_MEMORY), "Unable to allocate dex file array for class loader");
return false;
}
}
cur_data->SetNewDexCache(CreateNewDexCache(loader));
if (cur_data->GetNewDexCache() == nullptr) {
driver_->self_->AssertPendingException();
driver_->self_->ClearException();
RecordFailure(ERR(OUT_OF_MEMORY), "Unable to allocate DexCache");
return false;
}
// We won't always need to set this field.
cur_data->SetOriginalDexFile(AllocateOrGetOriginalDexFile());
if (cur_data->GetOriginalDexFile() == nullptr) {
driver_->self_->AssertPendingOOMException();
driver_->self_->ClearException();
RecordFailure(ERR(OUT_OF_MEMORY), "Unable to allocate array for original dex file");
return false;
}
if (added_fields_ || added_methods_) {
art::Handle<art::mirror::Class> nc(hs.NewHandle(
AllocateNewClassObject(hs.NewHandle(cur_data->GetNewDexCache()))));
if (nc.IsNull()) {
driver_->self_->ClearException();
RecordFailure(ERR(OUT_OF_MEMORY), "Unable to allocate new class object");
return false;
}
cur_data->SetNewClassObject(nc.Get());
// We really want to be able to resolve to the new class-object using this dex-cache for
// verification work. Since we haven't put it in the class-table yet we wll just manually add it
// to the dex-cache.
// TODO: We should maybe do this in a better spot.
cur_data->GetNewDexCache()->SetResolvedType(nc->GetDexTypeIndex(), nc.Get());
}
return true;
}
uint32_t Redefiner::ClassRedefinition::GetNewClassSize(bool with_embedded_tables,
art::Handle<art::mirror::Class> old_klass) {
// TODO Once we can add methods this won't work any more.
uint32_t num_vtable_entries = old_klass->GetVTableLength();
uint32_t num_8bit_static_fields = 0;
uint32_t num_16bit_static_fields = 0;
uint32_t num_32bit_static_fields = 0;
uint32_t num_64bit_static_fields = 0;
uint32_t num_ref_static_fields = 0;
art::ClassAccessor accessor(*dex_file_, dex_file_->GetClassDef(0));
for (const art::ClassAccessor::Field& f : accessor.GetStaticFields()) {
std::string_view desc(dex_file_->GetFieldTypeDescriptor(dex_file_->GetFieldId(f.GetIndex())));
if (desc[0] == 'L' || desc[0] == '[') {
num_ref_static_fields++;
} else if (desc == "Z" || desc == "B") {
num_8bit_static_fields++;
} else if (desc == "C" || desc == "S") {
num_16bit_static_fields++;
} else if (desc == "I" || desc == "F") {
num_32bit_static_fields++;
} else if (desc == "J" || desc == "D") {
num_64bit_static_fields++;
} else {
LOG(FATAL) << "Unknown type descriptor! " << desc;
}
}
return art::mirror::Class::ComputeClassSize(with_embedded_tables,
with_embedded_tables ? num_vtable_entries : 0,
num_8bit_static_fields,
num_16bit_static_fields,
num_32bit_static_fields,
num_64bit_static_fields,
num_ref_static_fields,
art::kRuntimePointerSize);
}
art::ObjPtr<art::mirror::Class>
Redefiner::ClassRedefinition::AllocateNewClassObject(art::Handle<art::mirror::DexCache> cache) {
// This is a stripped down DefineClass. We don't want to use DefineClass directly because it needs
// to perform a lot of extra steps to tell the ClassTable and the jit and everything about a new
// class. For now we will need to rely on our tests catching any issues caused by changes in how
// class_linker sets up classes.
// TODO Unify/move this into ClassLinker maybe.
art::StackHandleScope<5> hs(driver_->self_);
art::ClassLinker* linker = driver_->runtime_->GetClassLinker();
art::Handle<art::mirror::Class> old_class(hs.NewHandle(GetMirrorClass()));
art::Handle<art::mirror::Class> new_class(hs.NewHandle(linker->AllocClass(
driver_->self_, GetNewClassSize(/*with_embedded_tables=*/false, old_class))));
if (new_class.IsNull()) {
driver_->self_->AssertPendingOOMException();
JVMTI_LOG(ERROR, driver_->env_) << "Unable to allocate new class object!";
return nullptr;
}
new_class->SetDexCache(cache.Get());
linker->SetupClass(*dex_file_, dex_file_->GetClassDef(0), new_class, old_class->GetClassLoader());
// Make sure we are ready for linking. The lock isn't really needed since this isn't visible to
// other threads but the linker expects it.
art::ObjectLock<art::mirror::Class> lock(driver_->self_, new_class);
new_class->SetClinitThreadId(driver_->self_->GetTid());
// Make sure we have a valid empty iftable even if there are errors.
new_class->SetIfTable(art::GetClassRoot<art::mirror::Object>(linker)->GetIfTable());
linker->LoadClass(driver_->self_, *dex_file_, dex_file_->GetClassDef(0), new_class);
// NB. We know the interfaces and supers didn't change! :)
art::MutableHandle<art::mirror::Class> linked_class(hs.NewHandle<art::mirror::Class>(nullptr));
art::Handle<art::mirror::ObjectArray<art::mirror::Class>> proxy_ifaces(
hs.NewHandle<art::mirror::ObjectArray<art::mirror::Class>>(nullptr));
// No changing hierarchy so everything is loaded.
new_class->SetSuperClass(old_class->GetSuperClass());
art::mirror::Class::SetStatus(new_class, art::ClassStatus::kLoaded, nullptr);
if (!linker->LinkClass(driver_->self_, nullptr, new_class, proxy_ifaces, &linked_class)) {
JVMTI_LOG(ERROR, driver_->env_)
<< "failed to link class due to "
<< (driver_->self_->IsExceptionPending() ? driver_->self_->GetException()->Dump()
: " unknown");
driver_->self_->ClearException();
return nullptr;
}
// We will initialize it manually.
art::ObjectLock<art::mirror::Class> objlock(driver_->self_, linked_class);
// We already verified the class earlier. No need to do it again.
linked_class->SetVerificationAttempted();
// Mark the class as initialized.
CHECK(old_class->IsInitialized())
<< "Attempting to redefine an uninitalized class " << old_class->PrettyClass()
<< " status=" << old_class->GetStatus();
linker->ForceClassInitialized(driver_->self_, linked_class);
// Make sure we have ext-data space for method & field ids. We won't know if we need them until
// it's too late to create them.
// TODO We might want to remove these arrays if they're not needed.
if (!art::mirror::Class::EnsureInstanceFieldIds(linked_class) ||
!art::mirror::Class::EnsureStaticFieldIds(linked_class) ||
!art::mirror::Class::EnsureMethodIds(linked_class)) {
driver_->self_->AssertPendingOOMException();
driver_->self_->ClearException();
JVMTI_LOG(ERROR, driver_->env_) << "Unable to allocate jni-id arrays!";
return nullptr;
}
// Finish setting up methods.
linked_class->VisitMethods([&](art::ArtMethod* m) REQUIRES_SHARED(art::Locks::mutator_lock_) {
linker->SetEntryPointsToInterpreter(m);
m->SetNotIntrinsic();
DCHECK(m->IsCopied() || m->GetDeclaringClass() == linked_class.Get())
<< m->PrettyMethod()
<< " m->GetDeclaringClass(): " << m->GetDeclaringClass()->PrettyClass()
<< " != linked_class.Get(): " << linked_class->PrettyClass();
}, art::kRuntimePointerSize);
if (art::kIsDebugBuild) {
linked_class->VisitFields([&](art::ArtField* f) REQUIRES_SHARED(art::Locks::mutator_lock_) {
DCHECK_EQ(f->GetDeclaringClass(), linked_class.Get());
});
}
return linked_class.Get();
}
void Redefiner::ClassRedefinition::UnregisterJvmtiBreakpoints() {
BreakpointUtil::RemoveBreakpointsInClass(driver_->env_, GetMirrorClass().Ptr());
}
void Redefiner::ClassRedefinition::UnregisterBreakpoints() {
if (LIKELY(!art::Dbg::IsDebuggerActive())) {
return;
}
art::JDWP::JdwpState* state = art::Dbg::GetJdwpState();
if (state != nullptr) {
state->UnregisterLocationEventsOnClass(GetMirrorClass());
}
}
void Redefiner::UnregisterAllBreakpoints() {
for (Redefiner::ClassRedefinition& redef : redefinitions_) {
redef.UnregisterBreakpoints();
redef.UnregisterJvmtiBreakpoints();
}
}
bool Redefiner::CheckAllRedefinitionAreValid() {
for (Redefiner::ClassRedefinition& redef : redefinitions_) {
if (!redef.CheckRedefinitionIsValid()) {
return false;
}
}
return true;
}
void Redefiner::RestoreObsoleteMethodMapsIfUnneeded(RedefinitionDataHolder& holder) {
for (RedefinitionDataIter data = holder.begin(); data != holder.end(); ++data) {
data.GetRedefinition().RestoreObsoleteMethodMapsIfUnneeded(&data);
}
}
bool Redefiner::EnsureAllClassAllocationsFinished(RedefinitionDataHolder& holder) {
for (RedefinitionDataIter data = holder.begin(); data != holder.end(); ++data) {
if (!data.GetRedefinition().EnsureClassAllocationsFinished(&data)) {
return false;
}
}
return true;
}
bool Redefiner::CollectAndCreateNewInstances(RedefinitionDataHolder& holder) {
for (RedefinitionDataIter data = holder.begin(); data != holder.end(); ++data) {
// Allocate the data this redefinition requires.
if (!data.GetRedefinition().CollectAndCreateNewInstances(&data)) {
return false;
}
}
return true;
}
bool Redefiner::FinishAllRemainingAllocations(RedefinitionDataHolder& holder) {
for (RedefinitionDataIter data = holder.begin(); data != holder.end(); ++data) {
// Allocate the data this redefinition requires.
if (!data.GetRedefinition().FinishRemainingAllocations(&data)) {
return false;
}
}
return true;
}
void Redefiner::ClassRedefinition::ReleaseDexFile() {
dex_file_.release(); // NOLINT b/117926937
}
void Redefiner::ReleaseAllDexFiles() {
for (Redefiner::ClassRedefinition& redef : redefinitions_) {
redef.ReleaseDexFile();
}
}
bool Redefiner::CheckAllClassesAreVerified(RedefinitionDataHolder& holder) {
for (RedefinitionDataIter data = holder.begin(); data != holder.end(); ++data) {
if (!data.GetRedefinition().CheckVerification(data)) {
return false;
}
}
return true;
}
class ScopedDisableConcurrentAndMovingGc {
public:
ScopedDisableConcurrentAndMovingGc(art::gc::Heap* heap, art::Thread* self)
: heap_(heap), self_(self) {
if (heap_->IsGcConcurrentAndMoving()) {
heap_->IncrementDisableMovingGC(self_);
}
}
~ScopedDisableConcurrentAndMovingGc() {
if (heap_->IsGcConcurrentAndMoving()) {
heap_->DecrementDisableMovingGC(self_);
}
}
private:
art::gc::Heap* heap_;
art::Thread* self_;
};
class ScopedSuspendAllocations {
public:
ScopedSuspendAllocations(art::Runtime* runtime, RedefinitionDataHolder& h)
REQUIRES_SHARED(art::Locks::mutator_lock_)
: paused_(false) {
if (std::any_of(h.begin(),
h.end(),
[](auto r) REQUIRES_SHARED(art::Locks::mutator_lock_) {
return r.GetRedefinition().IsStructuralRedefinition();
})) {
VLOG(plugin) << "Pausing allocations for structural redefinition.";
paused_ = true;
AllocationManager::Get()->PauseAllocations(art::Thread::Current());
// Collect garbage so we don't need to recreate as much.
runtime->GetHeap()->CollectGarbage(/*clear_soft_references=*/false);
}
}
~ScopedSuspendAllocations() REQUIRES_SHARED(art::Locks::mutator_lock_) {
if (paused_) {
AllocationManager::Get()->ResumeAllocations(art::Thread::Current());
}
}
private:
bool paused_;
DISALLOW_COPY_AND_ASSIGN(ScopedSuspendAllocations);
};
jvmtiError Redefiner::Run() {
art::StackHandleScope<1> hs(self_);
// Allocate an array to hold onto all java temporary objects associated with this redefinition.
// We will let this be collected after the end of this function.
RedefinitionDataHolder holder(&hs, runtime_, self_, &redefinitions_);
if (holder.IsNull()) {
self_->AssertPendingOOMException();
self_->ClearException();
RecordFailure(ERR(OUT_OF_MEMORY), "Could not allocate storage for temporaries");
return result_;
}
// First we just allocate the ClassExt and its fields that we need. These can be updated
// atomically without any issues (since we allocate the map arrays as empty) so we don't bother
// doing a try loop. The other allocations we need to ensure that nothing has changed in the time
// between allocating them and pausing all threads before we can update them so we need to do a
// try loop.
if (!CheckAllRedefinitionAreValid() ||
!EnsureAllClassAllocationsFinished(holder) ||
!FinishAllRemainingAllocations(holder) ||
!CheckAllClassesAreVerified(holder)) {
return result_;
}
ScopedSuspendAllocations suspend_alloc(runtime_, holder);
if (!CollectAndCreateNewInstances(holder)) {
return result_;
}
// At this point we can no longer fail without corrupting the runtime state.
for (RedefinitionDataIter data = holder.begin(); data != holder.end(); ++data) {
art::ClassLinker* cl = runtime_->GetClassLinker();
cl->RegisterExistingDexCache(data.GetNewDexCache(), data.GetSourceClassLoader());
if (data.GetSourceClassLoader() == nullptr) {
cl->AppendToBootClassPath(self_, &data.GetRedefinition().GetDexFile());
}
}
UnregisterAllBreakpoints();
{
// Disable GC and wait for it to be done if we are a moving GC. This is fine since we are done
// allocating so no deadlocks.
ScopedDisableConcurrentAndMovingGc sdcamgc(runtime_->GetHeap(), self_);
// Do transition to final suspension
// TODO We might want to give this its own suspended state!
// TODO This isn't right. We need to change state without any chance of suspend ideally!
art::ScopedThreadSuspension sts(self_, art::ThreadState::kNative);
art::ScopedSuspendAll ssa("Final installation of redefined Classes!", /*long_suspend=*/true);
for (RedefinitionDataIter data = holder.begin(); data != holder.end(); ++data) {
art::ScopedAssertNoThreadSuspension nts("Updating runtime objects for redefinition");
ClassRedefinition& redef = data.GetRedefinition();
if (data.GetSourceClassLoader() != nullptr) {
ClassLoaderHelper::UpdateJavaDexFile(data.GetJavaDexFile(), data.GetNewDexFileCookie());
}
redef.UpdateClass(data);
}
RestoreObsoleteMethodMapsIfUnneeded(holder);
// TODO We should check for if any of the redefined methods are intrinsic methods here and, if
// any are, force a full-world deoptimization before finishing redefinition. If we don't do this
// then methods that have been jitted prior to the current redefinition being applied might
// continue to use the old versions of the intrinsics!
// TODO Do the dex_file release at a more reasonable place. This works but it muddles who really
// owns the DexFile and when ownership is transferred.
ReleaseAllDexFiles();
}
// By now the class-linker knows about all the classes so we can safetly retry verification and
// update method flags.
ReverifyClasses(holder);
return OK;
}
void Redefiner::ReverifyClasses(RedefinitionDataHolder& holder) {
for (RedefinitionDataIter data = holder.begin(); data != holder.end(); ++data) {
data.GetRedefinition().ReverifyClass(data);
}
}
void Redefiner::ClassRedefinition::ReverifyClass(const RedefinitionDataIter &cur_data) {
if (!needs_reverify_) {
return;
}
VLOG(plugin) << "Reverifying " << class_sig_ << " due to soft failures";
std::string error;
// TODO Make verification log level lower
art::verifier::FailureKind failure =
art::verifier::ClassVerifier::ReverifyClass(driver_->self_,
cur_data.GetMirrorClass(),
/*log_level=*/
art::verifier::HardFailLogMode::kLogWarning,
/*api_level=*/
art::Runtime::Current()->GetTargetSdkVersion(),
&error);
CHECK_NE(failure, art::verifier::FailureKind::kHardFailure);
}
void Redefiner::ClassRedefinition::UpdateMethods(art::ObjPtr<art::mirror::Class> mclass,
const art::dex::ClassDef& class_def) {
art::ClassLinker* linker = driver_->runtime_->GetClassLinker();
art::PointerSize image_pointer_size = linker->GetImagePointerSize();
const art::dex::TypeId& declaring_class_id = dex_file_->GetTypeId(class_def.class_idx_);
const art::DexFile& old_dex_file = mclass->GetDexFile();
// Update methods.
for (art::ArtMethod& method : mclass->GetDeclaredMethods(image_pointer_size)) {
const art::dex::StringId* new_name_id = dex_file_->FindStringId(method.GetName());
art::dex::TypeIndex method_return_idx =
dex_file_->GetIndexForTypeId(*dex_file_->FindTypeId(method.GetReturnTypeDescriptor()));
const auto* old_type_list = method.GetParameterTypeList();
std::vector<art::dex::TypeIndex> new_type_list;
for (uint32_t i = 0; old_type_list != nullptr && i < old_type_list->Size(); i++) {
new_type_list.push_back(
dex_file_->GetIndexForTypeId(
*dex_file_->FindTypeId(
old_dex_file.GetTypeDescriptor(
old_dex_file.GetTypeId(
old_type_list->GetTypeItem(i).type_idx_)))));
}
const art::dex::ProtoId* proto_id = dex_file_->FindProtoId(method_return_idx, new_type_list);
CHECK(proto_id != nullptr || old_type_list == nullptr);
const art::dex::MethodId* method_id = dex_file_->FindMethodId(declaring_class_id,
*new_name_id,
*proto_id);
CHECK(method_id != nullptr);
uint32_t dex_method_idx = dex_file_->GetIndexForMethodId(*method_id);
method.SetDexMethodIndex(dex_method_idx);
linker->SetEntryPointsToInterpreter(&method);
method.SetCodeItemOffset(dex_file_->FindCodeItemOffset(class_def, dex_method_idx));
// Clear all the intrinsics related flags.
method.SetNotIntrinsic();
}
}
void Redefiner::ClassRedefinition::UpdateFields(art::ObjPtr<art::mirror::Class> mclass) {
// TODO The IFields & SFields pointers should be combined like the methods_ arrays were.
for (auto fields_iter : {mclass->GetIFields(), mclass->GetSFields()}) {
for (art::ArtField& field : fields_iter) {
std::string declaring_class_name;
const art::dex::TypeId* new_declaring_id =
dex_file_->FindTypeId(field.GetDeclaringClass()->GetDescriptor(&declaring_class_name));
const art::dex::StringId* new_name_id = dex_file_->FindStringId(field.GetName());
const art::dex::TypeId* new_type_id = dex_file_->FindTypeId(field.GetTypeDescriptor());
CHECK(new_name_id != nullptr && new_type_id != nullptr && new_declaring_id != nullptr);
const art::dex::FieldId* new_field_id =
dex_file_->FindFieldId(*new_declaring_id, *new_name_id, *new_type_id);
CHECK(new_field_id != nullptr);
// We only need to update the index since the other data in the ArtField cannot be updated.
field.SetDexFieldIndex(dex_file_->GetIndexForFieldId(*new_field_id));
}
}
}
void Redefiner::ClassRedefinition::CollectNewFieldAndMethodMappings(
const RedefinitionDataIter& data,
std::map<art::ArtMethod*, art::ArtMethod*>* method_map,
std::map<art::ArtField*, art::ArtField*>* field_map) {
art::ObjPtr<art::mirror::Class> old_cls(data.GetMirrorClass());
art::ObjPtr<art::mirror::Class> new_cls(data.GetNewClassObject());
for (art::ArtField& f : old_cls->GetSFields()) {
(*field_map)[&f] = new_cls->FindDeclaredStaticField(f.GetName(), f.GetTypeDescriptor());
}
for (art::ArtField& f : old_cls->GetIFields()) {
(*field_map)[&f] = new_cls->FindDeclaredInstanceField(f.GetName(), f.GetTypeDescriptor());
}
auto new_methods = new_cls->GetMethods(art::kRuntimePointerSize);
for (art::ArtMethod& m : old_cls->GetMethods(art::kRuntimePointerSize)) {
// No support for finding methods in this way since it's generally not needed. Just do it the
// easy way.
auto nm_iter = std::find_if(
new_methods.begin(),
new_methods.end(),
[&](art::ArtMethod& cand) REQUIRES_SHARED(art::Locks::mutator_lock_) {
return cand.GetNameView() == m.GetNameView() && cand.GetSignature() == m.GetSignature();
});
CHECK(nm_iter != new_methods.end())
<< "Could not find redefined version of " << m.PrettyMethod();
(*method_map)[&m] = &(*nm_iter);
}
}
static void CopyField(art::ObjPtr<art::mirror::Object> target,
art::ArtField* new_field,
art::ObjPtr<art::mirror::Object> source,
art::ArtField& old_field) REQUIRES(art::Locks::mutator_lock_) {
art::Primitive::Type ftype = old_field.GetTypeAsPrimitiveType();
CHECK_EQ(ftype, new_field->GetTypeAsPrimitiveType())
<< old_field.PrettyField() << " vs " << new_field->PrettyField();
if (ftype == art::Primitive::kPrimNot) {
new_field->SetObject<false>(target, old_field.GetObject(source));
} else {
switch (ftype) {
#define UPDATE_FIELD(TYPE) \
case art::Primitive::kPrim##TYPE: \
new_field->Set##TYPE<false>(target, old_field.Get##TYPE(source)); \
break
UPDATE_FIELD(Int);
UPDATE_FIELD(Float);
UPDATE_FIELD(Long);
UPDATE_FIELD(Double);
UPDATE_FIELD(Short);
UPDATE_FIELD(Char);
UPDATE_FIELD(Byte);
UPDATE_FIELD(Boolean);
case art::Primitive::kPrimNot:
case art::Primitive::kPrimVoid:
LOG(FATAL) << "Unexpected field with type " << ftype << " found!";
UNREACHABLE();
#undef UPDATE_FIELD
}
}
}
static void CopyFields(bool is_static,
art::ObjPtr<art::mirror::Object> target,
art::ObjPtr<art::mirror::Class> target_class,
art::ObjPtr<art::mirror::Object> source,
art::ObjPtr<art::mirror::Class> source_class)
REQUIRES(art::Locks::mutator_lock_) {
DCHECK(!source_class->IsObjectClass() && !target_class->IsObjectClass())
<< "Should not be overriding object class fields. Target: " << target_class->PrettyClass()
<< " Source: " << source_class->PrettyClass();
for (art::ArtField& f : (is_static ? source_class->GetSFields() : source_class->GetIFields())) {
art::ArtField* new_field =
(is_static ? target_class->FindDeclaredStaticField(f.GetName(), f.GetTypeDescriptor())
: target_class->FindDeclaredInstanceField(f.GetName(), f.GetTypeDescriptor()));
CHECK(new_field != nullptr) << "could not find new version of " << f.PrettyField();
CopyField(target, new_field, source, f);
}
if (!is_static && !target_class->GetSuperClass()->IsObjectClass()) {
CopyFields(
is_static, target, target_class->GetSuperClass(), source, source_class->GetSuperClass());
}
}
static void ClearField(art::ObjPtr<art::mirror::Object> target, art::ArtField& field)
REQUIRES(art::Locks::mutator_lock_) {
art::Primitive::Type ftype = field.GetTypeAsPrimitiveType();
if (ftype == art::Primitive::kPrimNot) {
field.SetObject<false>(target, nullptr);
} else {
switch (ftype) {
#define UPDATE_FIELD(TYPE) \
case art::Primitive::kPrim##TYPE: \
field.Set##TYPE<false>(target, 0); \
break
UPDATE_FIELD(Int);
UPDATE_FIELD(Float);
UPDATE_FIELD(Long);
UPDATE_FIELD(Double);
UPDATE_FIELD(Short);
UPDATE_FIELD(Char);
UPDATE_FIELD(Byte);
UPDATE_FIELD(Boolean);
case art::Primitive::kPrimNot:
case art::Primitive::kPrimVoid:
LOG(FATAL) << "Unexpected field with type " << ftype << " found!";
UNREACHABLE();
#undef UPDATE_FIELD
}
}
}
static void ClearFields(bool is_static,
art::ObjPtr<art::mirror::Object> target,
art::ObjPtr<art::mirror::Class> target_class)
REQUIRES(art::Locks::mutator_lock_) {
DCHECK(!target_class->IsObjectClass());
for (art::ArtField& f : (is_static ? target_class->GetSFields() : target_class->GetIFields())) {
ClearField(target, f);
}
if (!is_static && !target_class->GetSuperClass()->IsObjectClass()) {
ClearFields(is_static, target, target_class->GetSuperClass());
}
}
static void CopyAndClearFields(bool is_static,
art::ObjPtr<art::mirror::Object> target,
art::ObjPtr<art::mirror::Class> target_class,
art::ObjPtr<art::mirror::Object> source,
art::ObjPtr<art::mirror::Class> source_class)
REQUIRES(art::Locks::mutator_lock_) {
// Copy all non-j.l.Object fields
CopyFields(is_static, target, target_class, source, source_class);
// Copy the lock-word.
target->SetLockWord(source->GetLockWord(false), false);
// Clear (reset) the old one.
source->SetLockWord(art::LockWord::Default(), false);
art::WriteBarrier::ForEveryFieldWrite(target);
// Clear the fields from the old class. We don't need it anymore.
ClearFields(is_static, source, source_class);
art::WriteBarrier::ForEveryFieldWrite(source);
}
void Redefiner::ClassRedefinition::UpdateClassStructurally(const RedefinitionDataIter& holder) {
DCHECK(IsStructuralRedefinition());
// LETS GO. We've got all new class structures so no need to do all the updating of the stacks.
// Instead we need to update everything else.
// Just replace the class and be done with it.
art::Locks::mutator_lock_->AssertExclusiveHeld(driver_->self_);
art::ScopedAssertNoThreadSuspension sants(__FUNCTION__);
art::ObjPtr<art::mirror::Class> orig(holder.GetMirrorClass());
art::ObjPtr<art::mirror::Class> replacement(holder.GetNewClassObject());
// Collect mappings from old to new fields/methods
std::map<art::ArtMethod*, art::ArtMethod*> method_map;
std::map<art::ArtField*, art::ArtField*> field_map;
CollectNewFieldAndMethodMappings(holder, &method_map, &field_map);
art::ObjPtr<art::mirror::ObjectArray<art::mirror::Object>> new_instances(
holder.GetNewInstanceObjects());
art::ObjPtr<art::mirror::ObjectArray<art::mirror::Object>> old_instances(
holder.GetOldInstanceObjects());
CHECK(!orig.IsNull());
CHECK(!replacement.IsNull());
// Copy over the static fields of the class and all the instance fields.
CopyAndClearFields(/*is_static=*/true, replacement, replacement, orig, orig);
// Copy and clear the fields of the old-instances.
for (int32_t i = 0; i < old_instances->GetLength(); i++) {
art::ObjPtr<art::mirror::Object> old_instance(old_instances->Get(i));
art::ObjPtr<art::mirror::Object> new_instance(new_instances->Get(i));
CopyAndClearFields(/*is_static=*/false,
new_instance,
new_instance->GetClass(),
old_instance,
old_instance->GetClass());
}
// Mark old class obsolete.
orig->SetObsoleteObject();
// Mark methods obsolete. We need to wait until later to actually clear the jit data.
for (art::ArtMethod& m : orig->GetMethods(art::kRuntimePointerSize)) {
m.SetIsObsolete();
m.SetDontCompile();
DCHECK_EQ(orig, m.GetDeclaringClass());
}
// Update live pointers in ART code.
auto could_change_resolution_of = [&](auto* field_or_method,
const auto& info) REQUIRES(art::Locks::mutator_lock_) {
constexpr bool is_method = std::is_same_v<art::ArtMethod*, decltype(field_or_method)>;
static_assert(is_method || std::is_same_v<art::ArtField*, decltype(field_or_method)>,
"Input is not field or method!");
// Only dex-cache is used for resolution
if (LIKELY(info.GetType() != art::ReflectionSourceType::kSourceDexCacheResolvedField &&
info.GetType() != art::ReflectionSourceType::kSourceDexCacheResolvedMethod)) {
return false;
}
if constexpr (is_method) {
// Only direct methods are used without further indirection through a vtable/IFTable.
// Constructors cannot be shadowed.
if (LIKELY(!field_or_method->IsDirect() || field_or_method->IsConstructor())) {
return false;
}
} else {
// Only non-private fields can be shadowed in a manner that's visible.
if (LIKELY(field_or_method->IsPrivate())) {
return false;
}
}
// We can only shadow things from our superclasses
if (LIKELY(!field_or_method->GetDeclaringClass()->IsAssignableFrom(orig))) {
return false;
}
if constexpr (is_method) {
auto direct_methods = replacement->GetDirectMethods(art::kRuntimePointerSize);
return std::find_if(direct_methods.begin(),
direct_methods.end(),
[&](art::ArtMethod& m) REQUIRES(art::Locks::mutator_lock_) {
return UNLIKELY(m.HasSameNameAndSignature(field_or_method));
}) != direct_methods.end();
} else {
auto pred = [&](art::ArtField& f) REQUIRES(art::Locks::mutator_lock_) {
return std::string_view(f.GetName()) == std::string_view(field_or_method->GetName()) &&
std::string_view(f.GetTypeDescriptor()) ==
std::string_view(field_or_method->GetTypeDescriptor());
};
if (field_or_method->IsStatic()) {
auto sfields = replacement->GetSFields();
return std::find_if(sfields.begin(), sfields.end(), pred) != sfields.end();
} else {
auto ifields = replacement->GetIFields();
return std::find_if(ifields.begin(), ifields.end(), pred) != ifields.end();
}
}
};
// TODO Performing 2 stack-walks back to back isn't the greatest. We might want to try to combine
// it with the one ReplaceReferences does. Doing so would be rather complicated though.
driver_->runtime_->VisitReflectiveTargets(
[&](art::ArtField* f, const auto& info) REQUIRES(art::Locks::mutator_lock_) {
DCHECK(f != nullptr) << info;
auto it = field_map.find(f);
if (it != field_map.end()) {
VLOG(plugin) << "Updating " << info << " object for (field) "
<< it->second->PrettyField();
return it->second;
} else if (UNLIKELY(could_change_resolution_of(f, info))) {
// Resolution might change. Just clear the resolved value.
VLOG(plugin) << "Clearing resolution " << info << " for (field) " << f->PrettyField();
return static_cast<art::ArtField*>(nullptr);
}
return f;
},
[&](art::ArtMethod* m, const auto& info) REQUIRES(art::Locks::mutator_lock_) {
DCHECK(m != nullptr) << info;
auto it = method_map.find(m);
if (it != method_map.end()) {
VLOG(plugin) << "Updating " << info << " object for (method) "
<< it->second->PrettyMethod();
return it->second;
} else if (UNLIKELY(could_change_resolution_of(m, info))) {
// Resolution might change. Just clear the resolved value.
VLOG(plugin) << "Clearing resolution " << info << " for (method) " << m->PrettyMethod();
return static_cast<art::ArtMethod*>(nullptr);
}
return m;
});
// Force every frame of every thread to deoptimize (any frame might have eg offsets compiled in).
driver_->runtime_->GetInstrumentation()->DeoptimizeAllThreadFrames();
std::unordered_map<art::ObjPtr<art::mirror::Object>,
art::ObjPtr<art::mirror::Object>,
art::HashObjPtr> map;
map.emplace(orig, replacement);
for (int32_t i = 0; i < old_instances->GetLength(); i++) {
map.emplace(old_instances->Get(i), new_instances->Get(i));
}
// Actually perform the general replacement. This doesn't affect ArtMethod/ArtFields. It does
// affect the declaring_class field of all the obsolete objects, which is unfortunate and needs to
// be undone. This replaces the mirror::Class in 'holder' as well. It's magic!
HeapExtensions::ReplaceReferences(driver_->self_, map);
// Save the old class so that the JIT gc doesn't get confused by it being collected before the
// jit code. This is also needed to keep the dex-caches of any obsolete methods live.
replacement->GetExtData()->SetObsoleteClass(orig);
art::jit::Jit* jit = driver_->runtime_->GetJit();
if (jit != nullptr) {
// Clear jit.
// TODO We might want to have some way to tell the JIT not to wait the kJitSamplesBatchSize
// invokes to start compiling things again.
jit->GetCodeCache()->InvalidateAllCompiledCode();
}
// Clear thread caches
{
// TODO We might be able to avoid doing this but given the rather unstructured nature of the
// interpreter cache it's probably not worth the effort.
art::MutexLock mu(driver_->self_, *art::Locks::thread_list_lock_);
driver_->runtime_->GetThreadList()->ForEach(
[](art::Thread* t) { t->GetInterpreterCache()->Clear(t); });
}
if (art::kIsDebugBuild) {
// Just make sure we didn't screw up any of the now obsolete methods or fields. We need their
// declaring-class to still be the obolete class
orig->VisitMethods([&](art::ArtMethod* method) REQUIRES_SHARED(art::Locks::mutator_lock_) {
DCHECK_EQ(method->GetDeclaringClass(), orig) << method->GetDeclaringClass()->PrettyClass()
<< " vs " << orig->PrettyClass();
}, art::kRuntimePointerSize);
orig->VisitFields([&](art::ArtField* field) REQUIRES_SHARED(art::Locks::mutator_lock_) {
DCHECK_EQ(field->GetDeclaringClass(), orig) << field->GetDeclaringClass()->PrettyClass()
<< " vs " << orig->PrettyClass();
});
}
}
// Redefines the class in place
void Redefiner::ClassRedefinition::UpdateClassInPlace(const RedefinitionDataIter& holder) {
art::ObjPtr<art::mirror::Class> mclass(holder.GetMirrorClass());
// TODO Rewrite so we don't do a stack walk for each and every class.
FindAndAllocateObsoleteMethods(mclass);
art::ObjPtr<art::mirror::DexCache> new_dex_cache(holder.GetNewDexCache());
art::ObjPtr<art::mirror::Object> original_dex_file(holder.GetOriginalDexFile());
DCHECK_EQ(dex_file_->NumClassDefs(), 1u);
const art::dex::ClassDef& class_def = dex_file_->GetClassDef(0);
UpdateMethods(mclass, class_def);
UpdateFields(mclass);
art::ObjPtr<art::mirror::ClassExt> ext(mclass->GetExtData());
CHECK(!ext.IsNull());
ext->SetOriginalDexFile(original_dex_file);
// If this is the first time the class is being redefined, store
// the native DexFile pointer and initial ClassDef index in ClassExt.
// This preserves the pointer for hiddenapi access checks which need
// to read access flags from the initial DexFile.
if (ext->GetPreRedefineDexFile() == nullptr) {
ext->SetPreRedefineDexFile(&mclass->GetDexFile());
ext->SetPreRedefineClassDefIndex(mclass->GetDexClassDefIndex());
}
// Update the class fields.
// Need to update class last since the ArtMethod gets its DexFile from the class (which is needed
// to call GetReturnTypeDescriptor and GetParameterTypeList above).
mclass->SetDexCache(new_dex_cache.Ptr());
mclass->SetDexClassDefIndex(dex_file_->GetIndexForClassDef(class_def));
mclass->SetDexTypeIndex(dex_file_->GetIndexForTypeId(*dex_file_->FindTypeId(class_sig_.c_str())));
// Notify the jit that all the methods in this class were redefined. Need to do this last since
// the jit relies on the dex_file_ being correct (for native methods at least) to find the method
// meta-data.
art::jit::Jit* jit = driver_->runtime_->GetJit();
if (jit != nullptr) {
art::PointerSize image_pointer_size =
driver_->runtime_->GetClassLinker()->GetImagePointerSize();
auto code_cache = jit->GetCodeCache();
// Non-invokable methods don't have any JIT data associated with them so we don't need to tell
// the jit about them.
for (art::ArtMethod& method : mclass->GetDeclaredMethods(image_pointer_size)) {
if (method.IsInvokable()) {
code_cache->NotifyMethodRedefined(&method);
}
}
}
}
// Performs final updates to class for redefinition.
void Redefiner::ClassRedefinition::UpdateClass(const RedefinitionDataIter& holder) {
if (IsStructuralRedefinition()) {
UpdateClassStructurally(holder);
} else {
UpdateClassInPlace(holder);
}
UpdateClassCommon(holder);
}
void Redefiner::ClassRedefinition::UpdateClassCommon(const RedefinitionDataIter &cur_data) {
// NB This is after we've already replaced all old-refs with new-refs in the structural case.
art::ObjPtr<art::mirror::Class> klass(cur_data.GetMirrorClass());
DCHECK(!IsStructuralRedefinition() || klass == cur_data.GetNewClassObject());
if (!needs_reverify_) {
return;
}
// Force the most restrictive interpreter environment. We don't know what the final verification
// will allow. We will clear these after retrying verification once we drop the mutator-lock.
klass->VisitMethods([](art::ArtMethod* m) REQUIRES_SHARED(art::Locks::mutator_lock_) {
if (!m->IsNative() && m->IsInvokable() && !m->IsObsolete()) {
m->ClearSkipAccessChecks();
m->SetDontCompile();
m->SetMustCountLocks();
}
}, art::kRuntimePointerSize);
}
// Restores the old obsolete methods maps if it turns out they weren't needed (ie there were no new
// obsolete methods).
void Redefiner::ClassRedefinition::RestoreObsoleteMethodMapsIfUnneeded(
const RedefinitionDataIter* cur_data) {
if (IsStructuralRedefinition()) {
// We didn't touch these in this case.
return;
}
art::ObjPtr<art::mirror::Class> klass = GetMirrorClass();
art::ObjPtr<art::mirror::ClassExt> ext = klass->GetExtData();
art::ObjPtr<art::mirror::PointerArray> methods = ext->GetObsoleteMethods();
art::ObjPtr<art::mirror::PointerArray> old_methods = cur_data->GetOldObsoleteMethods();
int32_t old_length = old_methods == nullptr ? 0 : old_methods->GetLength();
int32_t expected_length =
old_length + klass->NumDirectMethods() + klass->NumDeclaredVirtualMethods();
// Check to make sure we are only undoing this one.
if (methods.IsNull()) {
// No new obsolete methods! We can get rid of the maps.
ext->SetObsoleteArrays(cur_data->GetOldObsoleteMethods(), cur_data->GetOldDexCaches());
} else if (expected_length == methods->GetLength()) {
for (int32_t i = 0; i < expected_length; i++) {
art::ArtMethod* expected = nullptr;
if (i < old_length) {
expected = old_methods->GetElementPtrSize<art::ArtMethod*>(i, art::kRuntimePointerSize);
}
if (methods->GetElementPtrSize<art::ArtMethod*>(i, art::kRuntimePointerSize) != expected) {
// We actually have some new obsolete methods. Just abort since we cannot safely shrink the
// obsolete methods array.
return;
}
}
// No new obsolete methods! We can get rid of the maps.
ext->SetObsoleteArrays(cur_data->GetOldObsoleteMethods(), cur_data->GetOldDexCaches());
}
}
// This function does all (java) allocations we need to do for the Class being redefined.
// TODO Change this name maybe?
bool Redefiner::ClassRedefinition::EnsureClassAllocationsFinished(
/*out*/RedefinitionDataIter* cur_data) {
art::StackHandleScope<2> hs(driver_->self_);
art::Handle<art::mirror::Class> klass(hs.NewHandle(
driver_->self_->DecodeJObject(klass_)->AsClass()));
if (klass == nullptr) {
RecordFailure(ERR(INVALID_CLASS), "Unable to decode class argument!");
return false;
}
// Allocate the classExt
art::Handle<art::mirror::ClassExt> ext =
hs.NewHandle(art::mirror::Class::EnsureExtDataPresent(klass, driver_->self_));
if (ext == nullptr) {
// No memory. Clear exception (it's not useful) and return error.
driver_->self_->AssertPendingOOMException();
driver_->self_->ClearException();
RecordFailure(ERR(OUT_OF_MEMORY), "Could not allocate ClassExt");
return false;
}
if (!IsStructuralRedefinition()) {
// First save the old values of the 2 arrays that make up the obsolete methods maps. Then
// allocate the 2 arrays that make up the obsolete methods map. Since the contents of the arrays
// are only modified when all threads (other than the modifying one) are suspended we don't need
// to worry about missing the unsyncronized writes to the array. We do synchronize when setting
// it however, since that can happen at any time.
cur_data->SetOldObsoleteMethods(ext->GetObsoleteMethods());
cur_data->SetOldDexCaches(ext->GetObsoleteDexCaches());
if (!art::mirror::ClassExt::ExtendObsoleteArrays(
ext, driver_->self_, klass->GetDeclaredMethodsSlice(art::kRuntimePointerSize).size())) {
// OOM. Clear exception and return error.
driver_->self_->AssertPendingOOMException();
driver_->self_->ClearException();
RecordFailure(ERR(OUT_OF_MEMORY), "Unable to allocate/extend obsolete methods map");
return false;
}
}
return true;
}
} // namespace openjdkjvmti