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1 /* Copyright (C) 2016 The Android Open Source Project
2  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
3  *
4  * This file implements interfaces from the file jvmti.h. This implementation
5  * is licensed under the same terms as the file jvmti.h.  The
6  * copyright and license information for the file jvmti.h follows.
7  *
8  * Copyright (c) 2003, 2011, Oracle and/or its affiliates. All rights reserved.
9  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
10  *
11  * This code is free software; you can redistribute it and/or modify it
12  * under the terms of the GNU General Public License version 2 only, as
13  * published by the Free Software Foundation.  Oracle designates this
14  * particular file as subject to the "Classpath" exception as provided
15  * by Oracle in the LICENSE file that accompanied this code.
16  *
17  * This code is distributed in the hope that it will be useful, but WITHOUT
18  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
19  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
20  * version 2 for more details (a copy is included in the LICENSE file that
21  * accompanied this code).
22  *
23  * You should have received a copy of the GNU General Public License version
24  * 2 along with this work; if not, write to the Free Software Foundation,
25  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
26  *
27  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
28  * or visit www.oracle.com if you need additional information or have any
29  * questions.
30  */
31 
32 #include <stddef.h>
33 #include <sys/types.h>
34 
35 #include <unordered_map>
36 #include <unordered_set>
37 
38 #include "transform.h"
39 
40 #include "art_method.h"
41 #include "base/array_ref.h"
42 #include "base/globals.h"
43 #include "base/logging.h"
44 #include "base/mem_map.h"
45 #include "class_linker.h"
46 #include "dex/dex_file.h"
47 #include "dex/dex_file_types.h"
48 #include "dex/utf.h"
49 #include "events-inl.h"
50 #include "fault_handler.h"
51 #include "gc_root-inl.h"
52 #include "handle_scope-inl.h"
53 #include "jni/jni_env_ext-inl.h"
54 #include "jvalue.h"
55 #include "jvmti.h"
56 #include "linear_alloc.h"
57 #include "mirror/array.h"
58 #include "mirror/class-inl.h"
59 #include "mirror/class_ext.h"
60 #include "mirror/class_loader-inl.h"
61 #include "mirror/string-inl.h"
62 #include "oat_file.h"
63 #include "scoped_thread_state_change-inl.h"
64 #include "stack.h"
65 #include "thread_list.h"
66 #include "ti_redefine.h"
67 #include "transform.h"
68 #include "utils/dex_cache_arrays_layout-inl.h"
69 
70 namespace openjdkjvmti {
71 
72 // A FaultHandler that will deal with initializing ClassDefinitions when they are actually needed.
73 class TransformationFaultHandler final : public art::FaultHandler {
74  public:
TransformationFaultHandler(art::FaultManager * manager)75   explicit TransformationFaultHandler(art::FaultManager* manager)
76       : art::FaultHandler(manager),
77         uninitialized_class_definitions_lock_("JVMTI Initialized class definitions lock",
78                                               art::LockLevel::kSignalHandlingLock),
79         class_definition_initialized_cond_("JVMTI Initialized class definitions condition",
80                                            uninitialized_class_definitions_lock_) {
81     manager->AddHandler(this, /* generated_code= */ false);
82   }
83 
~TransformationFaultHandler()84   ~TransformationFaultHandler() {
85     art::MutexLock mu(art::Thread::Current(), uninitialized_class_definitions_lock_);
86     uninitialized_class_definitions_.clear();
87   }
88 
Action(int sig,siginfo_t * siginfo,void * context ATTRIBUTE_UNUSED)89   bool Action(int sig, siginfo_t* siginfo, void* context ATTRIBUTE_UNUSED) override {
90     DCHECK_EQ(sig, SIGSEGV);
91     art::Thread* self = art::Thread::Current();
92     if (UNLIKELY(uninitialized_class_definitions_lock_.IsExclusiveHeld(self))) {
93       if (self != nullptr) {
94         LOG(FATAL) << "Recursive call into Transformation fault handler!";
95         UNREACHABLE();
96       } else {
97         LOG(ERROR) << "Possible deadlock due to recursive signal delivery of segv.";
98       }
99     }
100     uintptr_t ptr = reinterpret_cast<uintptr_t>(siginfo->si_addr);
101     ArtClassDefinition* res = nullptr;
102 
103     {
104       // NB Technically using a mutex and condition variables here is non-posix compliant but
105       // everything should be fine since both glibc and bionic implementations of mutexs and
106       // condition variables work fine so long as the thread was not interrupted during a
107       // lock/unlock (which it wasn't) on all architectures we care about.
108       art::MutexLock mu(self, uninitialized_class_definitions_lock_);
109       auto it = std::find_if(uninitialized_class_definitions_.begin(),
110                              uninitialized_class_definitions_.end(),
111                              [&](const auto op) { return op->ContainsAddress(ptr); });
112       if (it != uninitialized_class_definitions_.end()) {
113         res = *it;
114         // Remove the class definition.
115         uninitialized_class_definitions_.erase(it);
116         // Put it in the initializing list
117         initializing_class_definitions_.push_back(res);
118       } else {
119         // Wait for the ptr to be initialized (if it is currently initializing).
120         while (DefinitionIsInitializing(ptr)) {
121           WaitForClassInitializationToFinish();
122         }
123         // Return true (continue with user code) if we find that the definition has been
124         // initialized. Return false (continue on to next signal handler) if the definition is not
125         // initialized or found.
126         return std::find_if(initialized_class_definitions_.begin(),
127                             initialized_class_definitions_.end(),
128                             [&](const auto op) { return op->ContainsAddress(ptr); }) !=
129             initialized_class_definitions_.end();
130       }
131     }
132 
133     if (LIKELY(self != nullptr)) {
134       CHECK_EQ(self->GetState(), art::ThreadState::kNative)
135           << "Transformation fault handler occurred outside of native mode";
136     }
137 
138     VLOG(signals) << "Lazy initialization of dex file for transformation of " << res->GetName()
139                   << " during SEGV";
140     res->InitializeMemory();
141 
142     {
143       art::MutexLock mu(self, uninitialized_class_definitions_lock_);
144       // Move to initialized state and notify waiters.
145       initializing_class_definitions_.erase(std::find(initializing_class_definitions_.begin(),
146                                                       initializing_class_definitions_.end(),
147                                                       res));
148       initialized_class_definitions_.push_back(res);
149       class_definition_initialized_cond_.Broadcast(self);
150     }
151 
152     return true;
153   }
154 
RemoveDefinition(ArtClassDefinition * def)155   void RemoveDefinition(ArtClassDefinition* def) REQUIRES(!uninitialized_class_definitions_lock_) {
156     art::MutexLock mu(art::Thread::Current(), uninitialized_class_definitions_lock_);
157     auto it = std::find(uninitialized_class_definitions_.begin(),
158                         uninitialized_class_definitions_.end(),
159                         def);
160     if (it != uninitialized_class_definitions_.end()) {
161       uninitialized_class_definitions_.erase(it);
162       return;
163     }
164     while (std::find(initializing_class_definitions_.begin(),
165                      initializing_class_definitions_.end(),
166                      def) != initializing_class_definitions_.end()) {
167       WaitForClassInitializationToFinish();
168     }
169     it = std::find(initialized_class_definitions_.begin(),
170                    initialized_class_definitions_.end(),
171                    def);
172     CHECK(it != initialized_class_definitions_.end()) << "Could not find class definition for "
173                                                       << def->GetName();
174     initialized_class_definitions_.erase(it);
175   }
176 
AddArtDefinition(ArtClassDefinition * def)177   void AddArtDefinition(ArtClassDefinition* def) REQUIRES(!uninitialized_class_definitions_lock_) {
178     DCHECK(def->IsLazyDefinition());
179     art::MutexLock mu(art::Thread::Current(), uninitialized_class_definitions_lock_);
180     uninitialized_class_definitions_.push_back(def);
181   }
182 
183  private:
DefinitionIsInitializing(uintptr_t ptr)184   bool DefinitionIsInitializing(uintptr_t ptr) REQUIRES(uninitialized_class_definitions_lock_) {
185     return std::find_if(initializing_class_definitions_.begin(),
186                         initializing_class_definitions_.end(),
187                         [&](const auto op) { return op->ContainsAddress(ptr); }) !=
188         initializing_class_definitions_.end();
189   }
190 
WaitForClassInitializationToFinish()191   void WaitForClassInitializationToFinish() REQUIRES(uninitialized_class_definitions_lock_) {
192     class_definition_initialized_cond_.Wait(art::Thread::Current());
193   }
194 
195   art::Mutex uninitialized_class_definitions_lock_ ACQUIRED_BEFORE(art::Locks::abort_lock_);
196   art::ConditionVariable class_definition_initialized_cond_
197       GUARDED_BY(uninitialized_class_definitions_lock_);
198 
199   // A list of the class definitions that have a non-readable map.
200   std::vector<ArtClassDefinition*> uninitialized_class_definitions_
201       GUARDED_BY(uninitialized_class_definitions_lock_);
202 
203   // A list of class definitions that are currently undergoing unquickening. Threads should wait
204   // until the definition is no longer in this before returning.
205   std::vector<ArtClassDefinition*> initializing_class_definitions_
206       GUARDED_BY(uninitialized_class_definitions_lock_);
207 
208   // A list of class definitions that are already unquickened. Threads should immediately return if
209   // it is here.
210   std::vector<ArtClassDefinition*> initialized_class_definitions_
211       GUARDED_BY(uninitialized_class_definitions_lock_);
212 };
213 
214 static TransformationFaultHandler* gTransformFaultHandler = nullptr;
215 
Setup()216 void Transformer::Setup() {
217   // Although we create this the fault handler is actually owned by the 'art::fault_manager' which
218   // will take care of destroying it.
219   if (art::MemMap::kCanReplaceMapping && ArtClassDefinition::kEnableOnDemandDexDequicken) {
220     gTransformFaultHandler = new TransformationFaultHandler(&art::fault_manager);
221   }
222 }
223 
224 // Simple helper to add and remove the class definition from the fault handler.
225 class ScopedDefinitionHandler {
226  public:
ScopedDefinitionHandler(ArtClassDefinition * def)227   explicit ScopedDefinitionHandler(ArtClassDefinition* def)
228       : def_(def), is_lazy_(def_->IsLazyDefinition()) {
229     if (is_lazy_) {
230       gTransformFaultHandler->AddArtDefinition(def_);
231     }
232   }
233 
~ScopedDefinitionHandler()234   ~ScopedDefinitionHandler() {
235     if (is_lazy_) {
236       gTransformFaultHandler->RemoveDefinition(def_);
237     }
238   }
239 
240  private:
241   ArtClassDefinition* def_;
242   bool is_lazy_;
243 };
244 
245 // Initialize templates.
246 template
247 void Transformer::TransformSingleClassDirect<ArtJvmtiEvent::kClassFileLoadHookNonRetransformable>(
248     EventHandler* event_handler, art::Thread* self, /*in-out*/ArtClassDefinition* def);
249 template
250 void Transformer::TransformSingleClassDirect<ArtJvmtiEvent::kClassFileLoadHookRetransformable>(
251     EventHandler* event_handler, art::Thread* self, /*in-out*/ArtClassDefinition* def);
252 
253 template<ArtJvmtiEvent kEvent>
TransformSingleClassDirect(EventHandler * event_handler,art::Thread * self,ArtClassDefinition * def)254 void Transformer::TransformSingleClassDirect(EventHandler* event_handler,
255                                              art::Thread* self,
256                                              /*in-out*/ArtClassDefinition* def) {
257   static_assert(kEvent == ArtJvmtiEvent::kClassFileLoadHookNonRetransformable ||
258                 kEvent == ArtJvmtiEvent::kClassFileLoadHookRetransformable,
259                 "bad event type");
260   // We don't want to do transitions between calling the event and setting the new data so change to
261   // native state early. This also avoids any problems that the FaultHandler might have in
262   // determining if an access to the dex_data is from generated code or not.
263   art::ScopedThreadStateChange stsc(self, art::ThreadState::kNative);
264   ScopedDefinitionHandler handler(def);
265   jint new_len = -1;
266   unsigned char* new_data = nullptr;
267   art::ArrayRef<const unsigned char> dex_data = def->GetDexData();
268   event_handler->DispatchEvent<kEvent>(
269       self,
270       static_cast<JNIEnv*>(self->GetJniEnv()),
271       def->GetClass(),
272       def->GetLoader(),
273       def->GetName().c_str(),
274       def->GetProtectionDomain(),
275       static_cast<jint>(dex_data.size()),
276       dex_data.data(),
277       /*out*/&new_len,
278       /*out*/&new_data);
279   def->SetNewDexData(new_len, new_data);
280 }
281 
RetransformClassesDirect(EventHandler * event_handler,art::Thread * self,std::vector<ArtClassDefinition> * definitions)282 jvmtiError Transformer::RetransformClassesDirect(
283       EventHandler* event_handler,
284       art::Thread* self,
285       /*in-out*/std::vector<ArtClassDefinition>* definitions) {
286   for (ArtClassDefinition& def : *definitions) {
287     TransformSingleClassDirect<ArtJvmtiEvent::kClassFileLoadHookRetransformable>(event_handler,
288                                                                                  self,
289                                                                                  &def);
290   }
291   return OK;
292 }
293 
RetransformClasses(ArtJvmTiEnv * env,EventHandler * event_handler,art::Runtime * runtime,art::Thread * self,jint class_count,const jclass * classes,std::string * error_msg)294 jvmtiError Transformer::RetransformClasses(ArtJvmTiEnv* env,
295                                            EventHandler* event_handler,
296                                            art::Runtime* runtime,
297                                            art::Thread* self,
298                                            jint class_count,
299                                            const jclass* classes,
300                                            /*out*/std::string* error_msg) {
301   if (env == nullptr) {
302     *error_msg = "env was null!";
303     return ERR(INVALID_ENVIRONMENT);
304   } else if (class_count < 0) {
305     *error_msg = "class_count was less then 0";
306     return ERR(ILLEGAL_ARGUMENT);
307   } else if (class_count == 0) {
308     // We don't actually need to do anything. Just return OK.
309     return OK;
310   } else if (classes == nullptr) {
311     *error_msg = "null classes!";
312     return ERR(NULL_POINTER);
313   }
314   // A holder that will Deallocate all the class bytes buffers on destruction.
315   std::vector<ArtClassDefinition> definitions;
316   jvmtiError res = OK;
317   for (jint i = 0; i < class_count; i++) {
318     res = Redefiner::GetClassRedefinitionError(classes[i], error_msg);
319     if (res != OK) {
320       return res;
321     }
322     ArtClassDefinition def;
323     res = def.Init(self, classes[i]);
324     if (res != OK) {
325       return res;
326     }
327     definitions.push_back(std::move(def));
328   }
329   res = RetransformClassesDirect(event_handler, self, &definitions);
330   if (res != OK) {
331     return res;
332   }
333   return Redefiner::RedefineClassesDirect(env, runtime, self, definitions, error_msg);
334 }
335 
336 // TODO Move this somewhere else, ti_class?
GetClassLocation(ArtJvmTiEnv * env,jclass klass,std::string * location)337 jvmtiError GetClassLocation(ArtJvmTiEnv* env, jclass klass, /*out*/std::string* location) {
338   JNIEnv* jni_env = nullptr;
339   jint ret = env->art_vm->GetEnv(reinterpret_cast<void**>(&jni_env), JNI_VERSION_1_1);
340   if (ret != JNI_OK) {
341     // TODO Different error might be better?
342     return ERR(INTERNAL);
343   }
344   art::ScopedObjectAccess soa(jni_env);
345   art::StackHandleScope<1> hs(art::Thread::Current());
346   art::Handle<art::mirror::Class> hs_klass(hs.NewHandle(soa.Decode<art::mirror::Class>(klass)));
347   const art::DexFile& dex = hs_klass->GetDexFile();
348   *location = dex.GetLocation();
349   return OK;
350 }
351 
352 }  // namespace openjdkjvmti
353