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      1 /*
      2  * Copyright (C) 2012 The Android Open Source Project
      3  *
      4  * Licensed under the Apache License, Version 2.0 (the "License");
      5  * you may not use this file except in compliance with the License.
      6  * You may obtain a copy of the License at
      7  *
      8  *      http://www.apache.org/licenses/LICENSE-2.0
      9  *
     10  * Unless required by applicable law or agreed to in writing, software
     11  * distributed under the License is distributed on an "AS IS" BASIS,
     12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
     13  * See the License for the specific language governing permissions and
     14  * limitations under the License.
     15  */
     16 
     17 #include "art_method-inl.h"
     18 #include "entrypoints/entrypoint_utils-inl.h"
     19 #include "mirror/object-inl.h"
     20 #include "thread-inl.h"
     21 #include "verify_object-inl.h"
     22 
     23 namespace art {
     24 
     25 extern void ReadBarrierJni(mirror::CompressedReference<mirror::Object>* handle_on_stack,
     26                            Thread* self ATTRIBUTE_UNUSED) {
     27   // Call the read barrier and update the handle.
     28   mirror::Object* to_ref = ReadBarrier::BarrierForRoot(handle_on_stack);
     29   handle_on_stack->Assign(to_ref);
     30 }
     31 
     32 // Called on entry to JNI, transition out of Runnable and release share of mutator_lock_.
     33 extern uint32_t JniMethodStart(Thread* self) {
     34   JNIEnvExt* env = self->GetJniEnv();
     35   DCHECK(env != nullptr);
     36   uint32_t saved_local_ref_cookie = env->local_ref_cookie;
     37   env->local_ref_cookie = env->locals.GetSegmentState();
     38   ArtMethod* native_method = *self->GetManagedStack()->GetTopQuickFrame();
     39   if (!native_method->IsFastNative()) {
     40     // When not fast JNI we transition out of runnable.
     41     self->TransitionFromRunnableToSuspended(kNative);
     42   }
     43   return saved_local_ref_cookie;
     44 }
     45 
     46 extern uint32_t JniMethodStartSynchronized(jobject to_lock, Thread* self) {
     47   self->DecodeJObject(to_lock)->MonitorEnter(self);
     48   return JniMethodStart(self);
     49 }
     50 
     51 // TODO: NO_THREAD_SAFETY_ANALYSIS due to different control paths depending on fast JNI.
     52 static void GoToRunnable(Thread* self) NO_THREAD_SAFETY_ANALYSIS {
     53   ArtMethod* native_method = *self->GetManagedStack()->GetTopQuickFrame();
     54   bool is_fast = native_method->IsFastNative();
     55   if (!is_fast) {
     56     self->TransitionFromSuspendedToRunnable();
     57   } else if (UNLIKELY(self->TestAllFlags())) {
     58     // In fast JNI mode we never transitioned out of runnable. Perform a suspend check if there
     59     // is a flag raised.
     60     DCHECK(Locks::mutator_lock_->IsSharedHeld(self));
     61     self->CheckSuspend();
     62   }
     63 }
     64 
     65 static void PopLocalReferences(uint32_t saved_local_ref_cookie, Thread* self)
     66     SHARED_REQUIRES(Locks::mutator_lock_) {
     67   JNIEnvExt* env = self->GetJniEnv();
     68   if (UNLIKELY(env->check_jni)) {
     69     env->CheckNoHeldMonitors();
     70   }
     71   env->locals.SetSegmentState(env->local_ref_cookie);
     72   env->local_ref_cookie = saved_local_ref_cookie;
     73   self->PopHandleScope();
     74 }
     75 
     76 extern void JniMethodEnd(uint32_t saved_local_ref_cookie, Thread* self) {
     77   GoToRunnable(self);
     78   PopLocalReferences(saved_local_ref_cookie, self);
     79 }
     80 
     81 extern void JniMethodEndSynchronized(uint32_t saved_local_ref_cookie, jobject locked,
     82                                      Thread* self) {
     83   GoToRunnable(self);
     84   UnlockJniSynchronizedMethod(locked, self);  // Must decode before pop.
     85   PopLocalReferences(saved_local_ref_cookie, self);
     86 }
     87 
     88 // Common result handling for EndWithReference.
     89 static mirror::Object* JniMethodEndWithReferenceHandleResult(jobject result,
     90                                                              uint32_t saved_local_ref_cookie,
     91                                                              Thread* self)
     92     NO_THREAD_SAFETY_ANALYSIS {
     93   // Must decode before pop. The 'result' may not be valid in case of an exception, though.
     94   mirror::Object* o = self->IsExceptionPending() ? nullptr : self->DecodeJObject(result);
     95   PopLocalReferences(saved_local_ref_cookie, self);
     96   // Process result.
     97   if (UNLIKELY(self->GetJniEnv()->check_jni)) {
     98     CheckReferenceResult(o, self);
     99   }
    100   VerifyObject(o);
    101   return o;
    102 }
    103 
    104 extern mirror::Object* JniMethodEndWithReference(jobject result, uint32_t saved_local_ref_cookie,
    105                                                  Thread* self) {
    106   GoToRunnable(self);
    107   return JniMethodEndWithReferenceHandleResult(result, saved_local_ref_cookie, self);
    108 }
    109 
    110 extern mirror::Object* JniMethodEndWithReferenceSynchronized(jobject result,
    111                                                              uint32_t saved_local_ref_cookie,
    112                                                              jobject locked, Thread* self) {
    113   GoToRunnable(self);
    114   UnlockJniSynchronizedMethod(locked, self);
    115   return JniMethodEndWithReferenceHandleResult(result, saved_local_ref_cookie, self);
    116 }
    117 
    118 extern uint64_t GenericJniMethodEnd(Thread* self,
    119                                     uint32_t saved_local_ref_cookie,
    120                                     jvalue result,
    121                                     uint64_t result_f,
    122                                     ArtMethod* called,
    123                                     HandleScope* handle_scope)
    124     // TODO: NO_THREAD_SAFETY_ANALYSIS as GoToRunnable() is NO_THREAD_SAFETY_ANALYSIS
    125     NO_THREAD_SAFETY_ANALYSIS {
    126   GoToRunnable(self);
    127   // We need the mutator lock (i.e., calling GoToRunnable()) before accessing the shorty or the
    128   // locked object.
    129   jobject locked = called->IsSynchronized() ? handle_scope->GetHandle(0).ToJObject() : nullptr;
    130   char return_shorty_char = called->GetShorty()[0];
    131   if (return_shorty_char == 'L') {
    132     if (locked != nullptr) {
    133       UnlockJniSynchronizedMethod(locked, self);
    134     }
    135     return reinterpret_cast<uint64_t>(JniMethodEndWithReferenceHandleResult(
    136         result.l, saved_local_ref_cookie, self));
    137   } else {
    138     if (locked != nullptr) {
    139       UnlockJniSynchronizedMethod(locked, self);  // Must decode before pop.
    140     }
    141     PopLocalReferences(saved_local_ref_cookie, self);
    142     switch (return_shorty_char) {
    143       case 'F': {
    144         if (kRuntimeISA == kX86) {
    145           // Convert back the result to float.
    146           double d = bit_cast<double, uint64_t>(result_f);
    147           return bit_cast<uint32_t, float>(static_cast<float>(d));
    148         } else {
    149           return result_f;
    150         }
    151       }
    152       case 'D':
    153         return result_f;
    154       case 'Z':
    155         return result.z;
    156       case 'B':
    157         return result.b;
    158       case 'C':
    159         return result.c;
    160       case 'S':
    161         return result.s;
    162       case 'I':
    163         return result.i;
    164       case 'J':
    165         return result.j;
    166       case 'V':
    167         return 0;
    168       default:
    169         LOG(FATAL) << "Unexpected return shorty character " << return_shorty_char;
    170         return 0;
    171     }
    172   }
    173 }
    174 
    175 }  // namespace art
    176