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1 /*
2  * Copyright (C) 2011 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 "image_writer.h"
18 
19 #include <sys/stat.h>
20 
21 #include <memory>
22 #include <vector>
23 
24 #include "base/logging.h"
25 #include "base/unix_file/fd_file.h"
26 #include "class_linker.h"
27 #include "compiled_method.h"
28 #include "dex_file-inl.h"
29 #include "driver/compiler_driver.h"
30 #include "elf_file.h"
31 #include "elf_utils.h"
32 #include "elf_patcher.h"
33 #include "elf_writer.h"
34 #include "gc/accounting/card_table-inl.h"
35 #include "gc/accounting/heap_bitmap.h"
36 #include "gc/accounting/space_bitmap-inl.h"
37 #include "gc/heap.h"
38 #include "gc/space/large_object_space.h"
39 #include "gc/space/space-inl.h"
40 #include "globals.h"
41 #include "image.h"
42 #include "intern_table.h"
43 #include "lock_word.h"
44 #include "mirror/art_field-inl.h"
45 #include "mirror/art_method-inl.h"
46 #include "mirror/array-inl.h"
47 #include "mirror/class-inl.h"
48 #include "mirror/class_loader.h"
49 #include "mirror/dex_cache-inl.h"
50 #include "mirror/object-inl.h"
51 #include "mirror/object_array-inl.h"
52 #include "mirror/string-inl.h"
53 #include "oat.h"
54 #include "oat_file.h"
55 #include "runtime.h"
56 #include "scoped_thread_state_change.h"
57 #include "handle_scope-inl.h"
58 
59 #include <numeric>
60 
61 using ::art::mirror::ArtField;
62 using ::art::mirror::ArtMethod;
63 using ::art::mirror::Class;
64 using ::art::mirror::DexCache;
65 using ::art::mirror::EntryPointFromInterpreter;
66 using ::art::mirror::Object;
67 using ::art::mirror::ObjectArray;
68 using ::art::mirror::String;
69 
70 namespace art {
71 
72 // Separate objects into multiple bins to optimize dirty memory use.
73 static constexpr bool kBinObjects = true;
74 
Write(const std::string & image_filename,uintptr_t image_begin,const std::string & oat_filename,const std::string & oat_location,bool compile_pic)75 bool ImageWriter::Write(const std::string& image_filename,
76                         uintptr_t image_begin,
77                         const std::string& oat_filename,
78                         const std::string& oat_location,
79                         bool compile_pic) {
80   CHECK(!image_filename.empty());
81 
82   CHECK_NE(image_begin, 0U);
83   image_begin_ = reinterpret_cast<byte*>(image_begin);
84   compile_pic_ = compile_pic;
85 
86   ClassLinker* class_linker = Runtime::Current()->GetClassLinker();
87 
88   target_ptr_size_ = InstructionSetPointerSize(compiler_driver_.GetInstructionSet());
89   std::unique_ptr<File> oat_file(OS::OpenFileReadWrite(oat_filename.c_str()));
90   if (oat_file.get() == NULL) {
91     LOG(ERROR) << "Failed to open oat file " << oat_filename << " for " << oat_location;
92     return false;
93   }
94   std::string error_msg;
95   oat_file_ = OatFile::OpenReadable(oat_file.get(), oat_location, &error_msg);
96   if (oat_file_ == nullptr) {
97     LOG(ERROR) << "Failed to open writable oat file " << oat_filename << " for " << oat_location
98         << ": " << error_msg;
99     return false;
100   }
101   CHECK_EQ(class_linker->RegisterOatFile(oat_file_), oat_file_);
102 
103   interpreter_to_interpreter_bridge_offset_ =
104       oat_file_->GetOatHeader().GetInterpreterToInterpreterBridgeOffset();
105   interpreter_to_compiled_code_bridge_offset_ =
106       oat_file_->GetOatHeader().GetInterpreterToCompiledCodeBridgeOffset();
107 
108   jni_dlsym_lookup_offset_ = oat_file_->GetOatHeader().GetJniDlsymLookupOffset();
109 
110   portable_imt_conflict_trampoline_offset_ =
111       oat_file_->GetOatHeader().GetPortableImtConflictTrampolineOffset();
112   portable_resolution_trampoline_offset_ =
113       oat_file_->GetOatHeader().GetPortableResolutionTrampolineOffset();
114   portable_to_interpreter_bridge_offset_ =
115       oat_file_->GetOatHeader().GetPortableToInterpreterBridgeOffset();
116 
117   quick_generic_jni_trampoline_offset_ =
118       oat_file_->GetOatHeader().GetQuickGenericJniTrampolineOffset();
119   quick_imt_conflict_trampoline_offset_ =
120       oat_file_->GetOatHeader().GetQuickImtConflictTrampolineOffset();
121   quick_resolution_trampoline_offset_ =
122       oat_file_->GetOatHeader().GetQuickResolutionTrampolineOffset();
123   quick_to_interpreter_bridge_offset_ =
124       oat_file_->GetOatHeader().GetQuickToInterpreterBridgeOffset();
125   {
126     Thread::Current()->TransitionFromSuspendedToRunnable();
127     PruneNonImageClasses();  // Remove junk
128     ComputeLazyFieldsForImageClasses();  // Add useful information
129     ProcessStrings();
130     Thread::Current()->TransitionFromRunnableToSuspended(kNative);
131   }
132   gc::Heap* heap = Runtime::Current()->GetHeap();
133   heap->CollectGarbage(false);  // Remove garbage.
134 
135   if (!AllocMemory()) {
136     return false;
137   }
138 
139   if (kIsDebugBuild) {
140     ScopedObjectAccess soa(Thread::Current());
141     CheckNonImageClassesRemoved();
142   }
143 
144   Thread::Current()->TransitionFromSuspendedToRunnable();
145   size_t oat_loaded_size = 0;
146   size_t oat_data_offset = 0;
147   ElfWriter::GetOatElfInformation(oat_file.get(), oat_loaded_size, oat_data_offset);
148   CalculateNewObjectOffsets(oat_loaded_size, oat_data_offset);
149   CopyAndFixupObjects();
150 
151   PatchOatCodeAndMethods(oat_file.get());
152 
153   // Before flushing, which might fail, release the mutator lock.
154   Thread::Current()->TransitionFromRunnableToSuspended(kNative);
155 
156   if (oat_file->FlushCloseOrErase() != 0) {
157     LOG(ERROR) << "Failed to flush and close oat file " << oat_filename << " for " << oat_location;
158     return false;
159   }
160 
161   std::unique_ptr<File> image_file(OS::CreateEmptyFile(image_filename.c_str()));
162   ImageHeader* image_header = reinterpret_cast<ImageHeader*>(image_->Begin());
163   if (image_file.get() == NULL) {
164     LOG(ERROR) << "Failed to open image file " << image_filename;
165     return false;
166   }
167   if (fchmod(image_file->Fd(), 0644) != 0) {
168     PLOG(ERROR) << "Failed to make image file world readable: " << image_filename;
169     image_file->Erase();
170     return EXIT_FAILURE;
171   }
172 
173   // Write out the image.
174   CHECK_EQ(image_end_, image_header->GetImageSize());
175   if (!image_file->WriteFully(image_->Begin(), image_end_)) {
176     PLOG(ERROR) << "Failed to write image file " << image_filename;
177     image_file->Erase();
178     return false;
179   }
180 
181   // Write out the image bitmap at the page aligned start of the image end.
182   CHECK_ALIGNED(image_header->GetImageBitmapOffset(), kPageSize);
183   if (!image_file->Write(reinterpret_cast<char*>(image_bitmap_->Begin()),
184                          image_header->GetImageBitmapSize(),
185                          image_header->GetImageBitmapOffset())) {
186     PLOG(ERROR) << "Failed to write image file " << image_filename;
187     image_file->Erase();
188     return false;
189   }
190 
191   if (image_file->FlushCloseOrErase() != 0) {
192     PLOG(ERROR) << "Failed to flush and close image file " << image_filename;
193     return false;
194   }
195   return true;
196 }
197 
SetImageOffset(mirror::Object * object,ImageWriter::BinSlot bin_slot,size_t offset)198 void ImageWriter::SetImageOffset(mirror::Object* object,
199                                  ImageWriter::BinSlot bin_slot,
200                                  size_t offset) {
201   DCHECK(object != nullptr);
202   DCHECK_NE(offset, 0U);
203   mirror::Object* obj = reinterpret_cast<mirror::Object*>(image_->Begin() + offset);
204   DCHECK_ALIGNED(obj, kObjectAlignment);
205 
206   image_bitmap_->Set(obj);  // Mark the obj as mutated, since we will end up changing it.
207   {
208     // Remember the object-inside-of-the-image's hash code so we can restore it after the copy.
209     auto hash_it = saved_hashes_map_.find(bin_slot);
210     if (hash_it != saved_hashes_map_.end()) {
211       std::pair<BinSlot, uint32_t> slot_hash = *hash_it;
212       saved_hashes_.push_back(std::make_pair(obj, slot_hash.second));
213       saved_hashes_map_.erase(hash_it);
214     }
215   }
216   // The object is already deflated from when we set the bin slot. Just overwrite the lock word.
217   object->SetLockWord(LockWord::FromForwardingAddress(offset), false);
218   DCHECK(IsImageOffsetAssigned(object));
219 }
220 
AssignImageOffset(mirror::Object * object,ImageWriter::BinSlot bin_slot)221 void ImageWriter::AssignImageOffset(mirror::Object* object, ImageWriter::BinSlot bin_slot) {
222   DCHECK(object != nullptr);
223   DCHECK_NE(image_objects_offset_begin_, 0u);
224 
225   size_t previous_bin_sizes = GetBinSizeSum(bin_slot.GetBin());  // sum sizes in [0..bin#)
226   size_t new_offset = image_objects_offset_begin_ + previous_bin_sizes + bin_slot.GetIndex();
227   DCHECK_ALIGNED(new_offset, kObjectAlignment);
228 
229   SetImageOffset(object, bin_slot, new_offset);
230   DCHECK_LT(new_offset, image_end_);
231 }
232 
IsImageOffsetAssigned(mirror::Object * object) const233 bool ImageWriter::IsImageOffsetAssigned(mirror::Object* object) const {
234   // Will also return true if the bin slot was assigned since we are reusing the lock word.
235   DCHECK(object != nullptr);
236   return object->GetLockWord(false).GetState() == LockWord::kForwardingAddress;
237 }
238 
GetImageOffset(mirror::Object * object) const239 size_t ImageWriter::GetImageOffset(mirror::Object* object) const {
240   DCHECK(object != nullptr);
241   DCHECK(IsImageOffsetAssigned(object));
242   LockWord lock_word = object->GetLockWord(false);
243   size_t offset = lock_word.ForwardingAddress();
244   DCHECK_LT(offset, image_end_);
245   return offset;
246 }
247 
SetImageBinSlot(mirror::Object * object,BinSlot bin_slot)248 void ImageWriter::SetImageBinSlot(mirror::Object* object, BinSlot bin_slot) {
249   DCHECK(object != nullptr);
250   DCHECK(!IsImageOffsetAssigned(object));
251   DCHECK(!IsImageBinSlotAssigned(object));
252 
253   // Before we stomp over the lock word, save the hash code for later.
254   Monitor::Deflate(Thread::Current(), object);;
255   LockWord lw(object->GetLockWord(false));
256   switch (lw.GetState()) {
257     case LockWord::kFatLocked: {
258       LOG(FATAL) << "Fat locked object " << object << " found during object copy";
259       break;
260     }
261     case LockWord::kThinLocked: {
262       LOG(FATAL) << "Thin locked object " << object << " found during object copy";
263       break;
264     }
265     case LockWord::kUnlocked:
266       // No hash, don't need to save it.
267       break;
268     case LockWord::kHashCode:
269       saved_hashes_map_[bin_slot] = lw.GetHashCode();
270       break;
271     default:
272       LOG(FATAL) << "Unreachable.";
273       break;
274   }
275   object->SetLockWord(LockWord::FromForwardingAddress(static_cast<uint32_t>(bin_slot)),
276                       false);
277   DCHECK(IsImageBinSlotAssigned(object));
278 }
279 
AssignImageBinSlot(mirror::Object * object)280 void ImageWriter::AssignImageBinSlot(mirror::Object* object) {
281   DCHECK(object != nullptr);
282   size_t object_size;
283   if (object->IsArtMethod()) {
284     // Methods are sized based on the target pointer size.
285     object_size = mirror::ArtMethod::InstanceSize(target_ptr_size_);
286   } else {
287     object_size = object->SizeOf();
288   }
289 
290   // The magic happens here. We segregate objects into different bins based
291   // on how likely they are to get dirty at runtime.
292   //
293   // Likely-to-dirty objects get packed together into the same bin so that
294   // at runtime their page dirtiness ratio (how many dirty objects a page has) is
295   // maximized.
296   //
297   // This means more pages will stay either clean or shared dirty (with zygote) and
298   // the app will use less of its own (private) memory.
299   Bin bin = kBinRegular;
300 
301   if (kBinObjects) {
302     //
303     // Changing the bin of an object is purely a memory-use tuning.
304     // It has no change on runtime correctness.
305     //
306     // Memory analysis has determined that the following types of objects get dirtied
307     // the most:
308     //
309     // * Class'es which are verified [their clinit runs only at runtime]
310     //   - classes in general [because their static fields get overwritten]
311     //   - initialized classes with all-final statics are unlikely to be ever dirty,
312     //     so bin them separately
313     // * Art Methods that are:
314     //   - native [their native entry point is not looked up until runtime]
315     //   - have declaring classes that aren't initialized
316     //            [their interpreter/quick entry points are trampolines until the class
317     //             becomes initialized]
318     //
319     // We also assume the following objects get dirtied either never or extremely rarely:
320     //  * Strings (they are immutable)
321     //  * Art methods that aren't native and have initialized declared classes
322     //
323     // We assume that "regular" bin objects are highly unlikely to become dirtied,
324     // so packing them together will not result in a noticeably tighter dirty-to-clean ratio.
325     //
326     if (object->IsClass()) {
327       bin = kBinClassVerified;
328       mirror::Class* klass = object->AsClass();
329 
330       if (klass->GetStatus() == Class::kStatusInitialized) {
331         bin = kBinClassInitialized;
332 
333         // If the class's static fields are all final, put it into a separate bin
334         // since it's very likely it will stay clean.
335         uint32_t num_static_fields = klass->NumStaticFields();
336         if (num_static_fields == 0) {
337           bin = kBinClassInitializedFinalStatics;
338         } else {
339           // Maybe all the statics are final?
340           bool all_final = true;
341           for (uint32_t i = 0; i < num_static_fields; ++i) {
342             ArtField* field = klass->GetStaticField(i);
343             if (!field->IsFinal()) {
344               all_final = false;
345               break;
346             }
347           }
348 
349           if (all_final) {
350             bin = kBinClassInitializedFinalStatics;
351           }
352         }
353       }
354     } else if (object->IsArtMethod<kVerifyNone>()) {
355       mirror::ArtMethod* art_method = down_cast<ArtMethod*>(object);
356       if (art_method->IsNative()) {
357         bin = kBinArtMethodNative;
358       } else {
359         mirror::Class* declaring_class = art_method->GetDeclaringClass();
360         if (declaring_class->GetStatus() != Class::kStatusInitialized) {
361           bin = kBinArtMethodNotInitialized;
362         } else {
363           // This is highly unlikely to dirty since there's no entry points to mutate.
364           bin = kBinArtMethodsManagedInitialized;
365         }
366       }
367     } else if (object->GetClass<kVerifyNone>()->IsStringClass()) {
368       bin = kBinString;  // Strings are almost always immutable (except for object header).
369     }  // else bin = kBinRegular
370   }
371 
372   size_t current_offset = bin_slot_sizes_[bin];  // How many bytes the current bin is at (aligned).
373   // Move the current bin size up to accomodate the object we just assigned a bin slot.
374   size_t offset_delta = RoundUp(object_size, kObjectAlignment);  // 64-bit alignment
375   bin_slot_sizes_[bin] += offset_delta;
376 
377   BinSlot new_bin_slot(bin, current_offset);
378   SetImageBinSlot(object, new_bin_slot);
379 
380   ++bin_slot_count_[bin];
381 
382   DCHECK_LT(GetBinSizeSum(), image_->Size());
383 
384   // Grow the image closer to the end by the object we just assigned.
385   image_end_ += offset_delta;
386   DCHECK_LT(image_end_, image_->Size());
387 }
388 
IsImageBinSlotAssigned(mirror::Object * object) const389 bool ImageWriter::IsImageBinSlotAssigned(mirror::Object* object) const {
390   DCHECK(object != nullptr);
391 
392   // We always stash the bin slot into a lockword, in the 'forwarding address' state.
393   // If it's in some other state, then we haven't yet assigned an image bin slot.
394   if (object->GetLockWord(false).GetState() != LockWord::kForwardingAddress) {
395     return false;
396   } else if (kIsDebugBuild) {
397     LockWord lock_word = object->GetLockWord(false);
398     size_t offset = lock_word.ForwardingAddress();
399     BinSlot bin_slot(offset);
400     DCHECK_LT(bin_slot.GetIndex(), bin_slot_sizes_[bin_slot.GetBin()])
401       << "bin slot offset should not exceed the size of that bin";
402   }
403   return true;
404 }
405 
GetImageBinSlot(mirror::Object * object) const406 ImageWriter::BinSlot ImageWriter::GetImageBinSlot(mirror::Object* object) const {
407   DCHECK(object != nullptr);
408   DCHECK(IsImageBinSlotAssigned(object));
409 
410   LockWord lock_word = object->GetLockWord(false);
411   size_t offset = lock_word.ForwardingAddress();  // TODO: ForwardingAddress should be uint32_t
412   DCHECK_LE(offset, std::numeric_limits<uint32_t>::max());
413 
414   BinSlot bin_slot(static_cast<uint32_t>(offset));
415   DCHECK_LT(bin_slot.GetIndex(), bin_slot_sizes_[bin_slot.GetBin()]);
416 
417   return bin_slot;
418 }
419 
AllocMemory()420 bool ImageWriter::AllocMemory() {
421   size_t length = RoundUp(Runtime::Current()->GetHeap()->GetTotalMemory(), kPageSize);
422   std::string error_msg;
423   image_.reset(MemMap::MapAnonymous("image writer image", NULL, length, PROT_READ | PROT_WRITE,
424                                     true, &error_msg));
425   if (UNLIKELY(image_.get() == nullptr)) {
426     LOG(ERROR) << "Failed to allocate memory for image file generation: " << error_msg;
427     return false;
428   }
429 
430   // Create the image bitmap.
431   image_bitmap_.reset(gc::accounting::ContinuousSpaceBitmap::Create("image bitmap", image_->Begin(),
432                                                                     length));
433   if (image_bitmap_.get() == nullptr) {
434     LOG(ERROR) << "Failed to allocate memory for image bitmap";
435     return false;
436   }
437   return true;
438 }
439 
ComputeLazyFieldsForImageClasses()440 void ImageWriter::ComputeLazyFieldsForImageClasses() {
441   ClassLinker* class_linker = Runtime::Current()->GetClassLinker();
442   class_linker->VisitClassesWithoutClassesLock(ComputeLazyFieldsForClassesVisitor, NULL);
443 }
444 
ComputeLazyFieldsForClassesVisitor(Class * c,void *)445 bool ImageWriter::ComputeLazyFieldsForClassesVisitor(Class* c, void* /*arg*/) {
446   Thread* self = Thread::Current();
447   StackHandleScope<1> hs(self);
448   mirror::Class::ComputeName(hs.NewHandle(c));
449   return true;
450 }
451 
452 // Count the number of strings in the heap and put the result in arg as a size_t pointer.
CountStringsCallback(Object * obj,void * arg)453 static void CountStringsCallback(Object* obj, void* arg)
454     SHARED_LOCKS_REQUIRED(Locks::mutator_lock_) {
455   if (obj->GetClass()->IsStringClass()) {
456     ++*reinterpret_cast<size_t*>(arg);
457   }
458 }
459 
460 // Collect all the java.lang.String in the heap and put them in the output strings_ array.
461 class StringCollector {
462  public:
StringCollector(Handle<mirror::ObjectArray<mirror::String>> strings,size_t index)463   StringCollector(Handle<mirror::ObjectArray<mirror::String>> strings, size_t index)
464       : strings_(strings), index_(index) {
465   }
Callback(Object * obj,void * arg)466   static void Callback(Object* obj, void* arg) SHARED_LOCKS_REQUIRED(Locks::mutator_lock_) {
467     auto* collector = reinterpret_cast<StringCollector*>(arg);
468     if (obj->GetClass()->IsStringClass()) {
469       collector->strings_->SetWithoutChecks<false>(collector->index_++, obj->AsString());
470     }
471   }
GetIndex() const472   size_t GetIndex() const {
473     return index_;
474   }
475 
476  private:
477   Handle<mirror::ObjectArray<mirror::String>> strings_;
478   size_t index_;
479 };
480 
481 // Compare strings based on length, used for sorting strings by length / reverse length.
482 class StringLengthComparator {
483  public:
StringLengthComparator(Handle<mirror::ObjectArray<mirror::String>> strings)484   explicit StringLengthComparator(Handle<mirror::ObjectArray<mirror::String>> strings)
485       : strings_(strings) {
486   }
operator ()(size_t a,size_t b) const487   bool operator()(size_t a, size_t b) const SHARED_LOCKS_REQUIRED(Locks::mutator_lock_) {
488     return strings_->GetWithoutChecks(a)->GetLength() < strings_->GetWithoutChecks(b)->GetLength();
489   }
490 
491  private:
492   Handle<mirror::ObjectArray<mirror::String>> strings_;
493 };
494 
495 // Normal string < comparison through the chars_ array.
496 class SubstringComparator {
497  public:
SubstringComparator(const std::vector<uint16_t> * const chars)498   explicit SubstringComparator(const std::vector<uint16_t>* const chars) : chars_(chars) {
499   }
operator ()(const std::pair<size_t,size_t> & a,const std::pair<size_t,size_t> & b)500   bool operator()(const std::pair<size_t, size_t>& a, const std::pair<size_t, size_t>& b) {
501     return std::lexicographical_compare(chars_->begin() + a.first,
502                                         chars_->begin() + a.first + a.second,
503                                         chars_->begin() + b.first,
504                                         chars_->begin() + b.first + b.second);
505   }
506 
507  private:
508   const std::vector<uint16_t>* const chars_;
509 };
510 
ProcessStrings()511 void ImageWriter::ProcessStrings() {
512   size_t total_strings = 0;
513   gc::Heap* heap = Runtime::Current()->GetHeap();
514   ClassLinker* cl = Runtime::Current()->GetClassLinker();
515   {
516     ReaderMutexLock mu(Thread::Current(), *Locks::heap_bitmap_lock_);
517     heap->VisitObjects(CountStringsCallback, &total_strings);  // Count the strings.
518   }
519   Thread* self = Thread::Current();
520   StackHandleScope<1> hs(self);
521   auto strings = hs.NewHandle(cl->AllocStringArray(self, total_strings));
522   StringCollector string_collector(strings, 0U);
523   {
524     ReaderMutexLock mu(Thread::Current(), *Locks::heap_bitmap_lock_);
525     // Read strings into the array.
526     heap->VisitObjects(StringCollector::Callback, &string_collector);
527   }
528   // Some strings could have gotten freed if AllocStringArray caused a GC.
529   CHECK_LE(string_collector.GetIndex(), total_strings);
530   total_strings = string_collector.GetIndex();
531   size_t total_length = 0;
532   std::vector<size_t> reverse_sorted_strings;
533   for (size_t i = 0; i < total_strings; ++i) {
534     mirror::String* s = strings->GetWithoutChecks(i);
535     // Look up the string in the array.
536     total_length += s->GetLength();
537     reverse_sorted_strings.push_back(i);
538   }
539   // Sort by reverse length.
540   StringLengthComparator comparator(strings);
541   std::sort(reverse_sorted_strings.rbegin(), reverse_sorted_strings.rend(), comparator);
542   // Deduplicate prefixes and add strings to the char array.
543   std::vector<uint16_t> combined_chars(total_length, 0U);
544   size_t num_chars = 0;
545   // Characters of strings which are non equal prefix of another string (not the same string).
546   // We don't count the savings from equal strings since these would get interned later anyways.
547   size_t prefix_saved_chars = 0;
548   std::set<std::pair<size_t, size_t>, SubstringComparator> existing_strings((
549       SubstringComparator(&combined_chars)));
550   for (size_t i = 0; i < total_strings; ++i) {
551     mirror::String* s = strings->GetWithoutChecks(reverse_sorted_strings[i]);
552     // Add the string to the end of the char array.
553     size_t length = s->GetLength();
554     for (size_t j = 0; j < length; ++j) {
555       combined_chars[num_chars++] = s->CharAt(j);
556     }
557     // Try to see if the string exists as a prefix of an existing string.
558     size_t new_offset = 0;
559     std::pair<size_t, size_t> new_string(num_chars - length, length);
560     auto it = existing_strings.lower_bound(new_string);
561     bool is_prefix = true;
562     if (it == existing_strings.end()) {
563       is_prefix = false;
564     } else {
565       CHECK_LE(length, it->second);
566       for (size_t j = 0; j < length; ++j) {
567         if (combined_chars[it->first + j] != s->CharAt(j)) {
568           is_prefix = false;
569           break;
570         }
571       }
572     }
573     if (is_prefix) {
574       // Shares a prefix, set the offset to where the new offset will be.
575       new_offset = it->first;
576       // Remove the added chars.
577       num_chars -= length;
578       if (it->second != length) {
579         prefix_saved_chars += length;
580       }
581     } else {
582       new_offset = new_string.first;
583       existing_strings.insert(new_string);
584     }
585     s->SetOffset(new_offset);
586   }
587   // Allocate and update the char arrays.
588   auto* array = mirror::CharArray::Alloc(self, num_chars);
589   for (size_t i = 0; i < num_chars; ++i) {
590     array->SetWithoutChecks<false>(i, combined_chars[i]);
591   }
592   for (size_t i = 0; i < total_strings; ++i) {
593     strings->GetWithoutChecks(i)->SetArray(array);
594   }
595   if (kIsDebugBuild || VLOG_IS_ON(compiler)) {
596     LOG(INFO) << "Total # image strings=" << total_strings << " combined length="
597         << total_length << " prefix saved chars=" << prefix_saved_chars;
598   }
599   ComputeEagerResolvedStrings();
600 }
601 
ComputeEagerResolvedStringsCallback(Object * obj,void * arg)602 void ImageWriter::ComputeEagerResolvedStringsCallback(Object* obj, void* arg) {
603   if (!obj->GetClass()->IsStringClass()) {
604     return;
605   }
606   mirror::String* string = obj->AsString();
607   const uint16_t* utf16_string = string->GetCharArray()->GetData() + string->GetOffset();
608   ClassLinker* class_linker = Runtime::Current()->GetClassLinker();
609   ReaderMutexLock mu(Thread::Current(), *class_linker->DexLock());
610   size_t dex_cache_count = class_linker->GetDexCacheCount();
611   for (size_t i = 0; i < dex_cache_count; ++i) {
612     DexCache* dex_cache = class_linker->GetDexCache(i);
613     const DexFile& dex_file = *dex_cache->GetDexFile();
614     const DexFile::StringId* string_id;
615     if (UNLIKELY(string->GetLength() == 0)) {
616       string_id = dex_file.FindStringId("");
617     } else {
618       string_id = dex_file.FindStringId(utf16_string);
619     }
620     if (string_id != nullptr) {
621       // This string occurs in this dex file, assign the dex cache entry.
622       uint32_t string_idx = dex_file.GetIndexForStringId(*string_id);
623       if (dex_cache->GetResolvedString(string_idx) == NULL) {
624         dex_cache->SetResolvedString(string_idx, string);
625       }
626     }
627   }
628 }
629 
ComputeEagerResolvedStrings()630 void ImageWriter::ComputeEagerResolvedStrings() {
631   ReaderMutexLock mu(Thread::Current(), *Locks::heap_bitmap_lock_);
632   Runtime::Current()->GetHeap()->VisitObjects(ComputeEagerResolvedStringsCallback, this);
633 }
634 
IsImageClass(Class * klass)635 bool ImageWriter::IsImageClass(Class* klass) {
636   std::string temp;
637   return compiler_driver_.IsImageClass(klass->GetDescriptor(&temp));
638 }
639 
640 struct NonImageClasses {
641   ImageWriter* image_writer;
642   std::set<std::string>* non_image_classes;
643 };
644 
PruneNonImageClasses()645 void ImageWriter::PruneNonImageClasses() {
646   if (compiler_driver_.GetImageClasses() == NULL) {
647     return;
648   }
649   Runtime* runtime = Runtime::Current();
650   ClassLinker* class_linker = runtime->GetClassLinker();
651 
652   // Make a list of classes we would like to prune.
653   std::set<std::string> non_image_classes;
654   NonImageClasses context;
655   context.image_writer = this;
656   context.non_image_classes = &non_image_classes;
657   class_linker->VisitClasses(NonImageClassesVisitor, &context);
658 
659   // Remove the undesired classes from the class roots.
660   for (const std::string& it : non_image_classes) {
661     bool result = class_linker->RemoveClass(it.c_str(), NULL);
662     DCHECK(result);
663   }
664 
665   // Clear references to removed classes from the DexCaches.
666   ArtMethod* resolution_method = runtime->GetResolutionMethod();
667   ReaderMutexLock mu(Thread::Current(), *class_linker->DexLock());
668   size_t dex_cache_count = class_linker->GetDexCacheCount();
669   for (size_t idx = 0; idx < dex_cache_count; ++idx) {
670     DexCache* dex_cache = class_linker->GetDexCache(idx);
671     for (size_t i = 0; i < dex_cache->NumResolvedTypes(); i++) {
672       Class* klass = dex_cache->GetResolvedType(i);
673       if (klass != NULL && !IsImageClass(klass)) {
674         dex_cache->SetResolvedType(i, NULL);
675       }
676     }
677     for (size_t i = 0; i < dex_cache->NumResolvedMethods(); i++) {
678       ArtMethod* method = dex_cache->GetResolvedMethod(i);
679       if (method != NULL && !IsImageClass(method->GetDeclaringClass())) {
680         dex_cache->SetResolvedMethod(i, resolution_method);
681       }
682     }
683     for (size_t i = 0; i < dex_cache->NumResolvedFields(); i++) {
684       ArtField* field = dex_cache->GetResolvedField(i);
685       if (field != NULL && !IsImageClass(field->GetDeclaringClass())) {
686         dex_cache->SetResolvedField(i, NULL);
687       }
688     }
689   }
690 }
691 
NonImageClassesVisitor(Class * klass,void * arg)692 bool ImageWriter::NonImageClassesVisitor(Class* klass, void* arg) {
693   NonImageClasses* context = reinterpret_cast<NonImageClasses*>(arg);
694   if (!context->image_writer->IsImageClass(klass)) {
695     std::string temp;
696     context->non_image_classes->insert(klass->GetDescriptor(&temp));
697   }
698   return true;
699 }
700 
CheckNonImageClassesRemoved()701 void ImageWriter::CheckNonImageClassesRemoved() {
702   if (compiler_driver_.GetImageClasses() != nullptr) {
703     gc::Heap* heap = Runtime::Current()->GetHeap();
704     ReaderMutexLock mu(Thread::Current(), *Locks::heap_bitmap_lock_);
705     heap->VisitObjects(CheckNonImageClassesRemovedCallback, this);
706   }
707 }
708 
CheckNonImageClassesRemovedCallback(Object * obj,void * arg)709 void ImageWriter::CheckNonImageClassesRemovedCallback(Object* obj, void* arg) {
710   ImageWriter* image_writer = reinterpret_cast<ImageWriter*>(arg);
711   if (obj->IsClass()) {
712     Class* klass = obj->AsClass();
713     if (!image_writer->IsImageClass(klass)) {
714       image_writer->DumpImageClasses();
715       std::string temp;
716       CHECK(image_writer->IsImageClass(klass)) << klass->GetDescriptor(&temp)
717                                                << " " << PrettyDescriptor(klass);
718     }
719   }
720 }
721 
DumpImageClasses()722 void ImageWriter::DumpImageClasses() {
723   const std::set<std::string>* image_classes = compiler_driver_.GetImageClasses();
724   CHECK(image_classes != NULL);
725   for (const std::string& image_class : *image_classes) {
726     LOG(INFO) << " " << image_class;
727   }
728 }
729 
CalculateObjectBinSlots(Object * obj)730 void ImageWriter::CalculateObjectBinSlots(Object* obj) {
731   DCHECK(obj != NULL);
732   // if it is a string, we want to intern it if its not interned.
733   if (obj->GetClass()->IsStringClass()) {
734     // we must be an interned string that was forward referenced and already assigned
735     if (IsImageBinSlotAssigned(obj)) {
736       DCHECK_EQ(obj, obj->AsString()->Intern());
737       return;
738     }
739     mirror::String* const interned = obj->AsString()->Intern();
740     if (obj != interned) {
741       if (!IsImageBinSlotAssigned(interned)) {
742         // interned obj is after us, allocate its location early
743         AssignImageBinSlot(interned);
744       }
745       // point those looking for this object to the interned version.
746       SetImageBinSlot(obj, GetImageBinSlot(interned));
747       return;
748     }
749     // else (obj == interned), nothing to do but fall through to the normal case
750   }
751 
752   AssignImageBinSlot(obj);
753 }
754 
CreateImageRoots() const755 ObjectArray<Object>* ImageWriter::CreateImageRoots() const {
756   Runtime* runtime = Runtime::Current();
757   ClassLinker* class_linker = runtime->GetClassLinker();
758   Thread* self = Thread::Current();
759   StackHandleScope<3> hs(self);
760   Handle<Class> object_array_class(hs.NewHandle(
761       class_linker->FindSystemClass(self, "[Ljava/lang/Object;")));
762 
763   // build an Object[] of all the DexCaches used in the source_space_.
764   // Since we can't hold the dex lock when allocating the dex_caches
765   // ObjectArray, we lock the dex lock twice, first to get the number
766   // of dex caches first and then lock it again to copy the dex
767   // caches. We check that the number of dex caches does not change.
768   size_t dex_cache_count;
769   {
770     ReaderMutexLock mu(Thread::Current(), *class_linker->DexLock());
771     dex_cache_count = class_linker->GetDexCacheCount();
772   }
773   Handle<ObjectArray<Object>> dex_caches(
774       hs.NewHandle(ObjectArray<Object>::Alloc(self, object_array_class.Get(),
775                                               dex_cache_count)));
776   CHECK(dex_caches.Get() != nullptr) << "Failed to allocate a dex cache array.";
777   {
778     ReaderMutexLock mu(Thread::Current(), *class_linker->DexLock());
779     CHECK_EQ(dex_cache_count, class_linker->GetDexCacheCount())
780         << "The number of dex caches changed.";
781     for (size_t i = 0; i < dex_cache_count; ++i) {
782       dex_caches->Set<false>(i, class_linker->GetDexCache(i));
783     }
784   }
785 
786   // build an Object[] of the roots needed to restore the runtime
787   Handle<ObjectArray<Object>> image_roots(hs.NewHandle(
788       ObjectArray<Object>::Alloc(self, object_array_class.Get(), ImageHeader::kImageRootsMax)));
789   image_roots->Set<false>(ImageHeader::kResolutionMethod, runtime->GetResolutionMethod());
790   image_roots->Set<false>(ImageHeader::kImtConflictMethod, runtime->GetImtConflictMethod());
791   image_roots->Set<false>(ImageHeader::kImtUnimplementedMethod,
792                           runtime->GetImtUnimplementedMethod());
793   image_roots->Set<false>(ImageHeader::kDefaultImt, runtime->GetDefaultImt());
794   image_roots->Set<false>(ImageHeader::kCalleeSaveMethod,
795                           runtime->GetCalleeSaveMethod(Runtime::kSaveAll));
796   image_roots->Set<false>(ImageHeader::kRefsOnlySaveMethod,
797                           runtime->GetCalleeSaveMethod(Runtime::kRefsOnly));
798   image_roots->Set<false>(ImageHeader::kRefsAndArgsSaveMethod,
799                           runtime->GetCalleeSaveMethod(Runtime::kRefsAndArgs));
800   image_roots->Set<false>(ImageHeader::kDexCaches, dex_caches.Get());
801   image_roots->Set<false>(ImageHeader::kClassRoots, class_linker->GetClassRoots());
802   for (int i = 0; i < ImageHeader::kImageRootsMax; i++) {
803     CHECK(image_roots->Get(i) != NULL);
804   }
805   return image_roots.Get();
806 }
807 
808 // Walk instance fields of the given Class. Separate function to allow recursion on the super
809 // class.
WalkInstanceFields(mirror::Object * obj,mirror::Class * klass)810 void ImageWriter::WalkInstanceFields(mirror::Object* obj, mirror::Class* klass) {
811   // Visit fields of parent classes first.
812   StackHandleScope<1> hs(Thread::Current());
813   Handle<mirror::Class> h_class(hs.NewHandle(klass));
814   mirror::Class* super = h_class->GetSuperClass();
815   if (super != nullptr) {
816     WalkInstanceFields(obj, super);
817   }
818   //
819   size_t num_reference_fields = h_class->NumReferenceInstanceFields();
820   MemberOffset field_offset = h_class->GetFirstReferenceInstanceFieldOffset();
821   for (size_t i = 0; i < num_reference_fields; ++i) {
822     mirror::Object* value = obj->GetFieldObject<mirror::Object>(field_offset);
823     if (value != nullptr) {
824       WalkFieldsInOrder(value);
825     }
826     field_offset = MemberOffset(field_offset.Uint32Value() +
827                                 sizeof(mirror::HeapReference<mirror::Object>));
828   }
829 }
830 
831 // For an unvisited object, visit it then all its children found via fields.
WalkFieldsInOrder(mirror::Object * obj)832 void ImageWriter::WalkFieldsInOrder(mirror::Object* obj) {
833   // Use our own visitor routine (instead of GC visitor) to get better locality between
834   // an object and its fields
835   if (!IsImageBinSlotAssigned(obj)) {
836     // Walk instance fields of all objects
837     StackHandleScope<2> hs(Thread::Current());
838     Handle<mirror::Object> h_obj(hs.NewHandle(obj));
839     Handle<mirror::Class> klass(hs.NewHandle(obj->GetClass()));
840     // visit the object itself.
841     CalculateObjectBinSlots(h_obj.Get());
842     WalkInstanceFields(h_obj.Get(), klass.Get());
843     // Walk static fields of a Class.
844     if (h_obj->IsClass()) {
845       size_t num_static_fields = klass->NumReferenceStaticFields();
846       MemberOffset field_offset = klass->GetFirstReferenceStaticFieldOffset();
847       for (size_t i = 0; i < num_static_fields; ++i) {
848         mirror::Object* value = h_obj->GetFieldObject<mirror::Object>(field_offset);
849         if (value != nullptr) {
850           WalkFieldsInOrder(value);
851         }
852         field_offset = MemberOffset(field_offset.Uint32Value() +
853                                     sizeof(mirror::HeapReference<mirror::Object>));
854       }
855     } else if (h_obj->IsObjectArray()) {
856       // Walk elements of an object array.
857       int32_t length = h_obj->AsObjectArray<mirror::Object>()->GetLength();
858       for (int32_t i = 0; i < length; i++) {
859         mirror::ObjectArray<mirror::Object>* obj_array = h_obj->AsObjectArray<mirror::Object>();
860         mirror::Object* value = obj_array->Get(i);
861         if (value != nullptr) {
862           WalkFieldsInOrder(value);
863         }
864       }
865     }
866   }
867 }
868 
WalkFieldsCallback(mirror::Object * obj,void * arg)869 void ImageWriter::WalkFieldsCallback(mirror::Object* obj, void* arg) {
870   ImageWriter* writer = reinterpret_cast<ImageWriter*>(arg);
871   DCHECK(writer != nullptr);
872   writer->WalkFieldsInOrder(obj);
873 }
874 
UnbinObjectsIntoOffsetCallback(mirror::Object * obj,void * arg)875 void ImageWriter::UnbinObjectsIntoOffsetCallback(mirror::Object* obj, void* arg) {
876   ImageWriter* writer = reinterpret_cast<ImageWriter*>(arg);
877   DCHECK(writer != nullptr);
878   writer->UnbinObjectsIntoOffset(obj);
879 }
880 
UnbinObjectsIntoOffset(mirror::Object * obj)881 void ImageWriter::UnbinObjectsIntoOffset(mirror::Object* obj) {
882   CHECK(obj != nullptr);
883 
884   // We know the bin slot, and the total bin sizes for all objects by now,
885   // so calculate the object's final image offset.
886 
887   DCHECK(IsImageBinSlotAssigned(obj));
888   BinSlot bin_slot = GetImageBinSlot(obj);
889   // Change the lockword from a bin slot into an offset
890   AssignImageOffset(obj, bin_slot);
891 }
892 
CalculateNewObjectOffsets(size_t oat_loaded_size,size_t oat_data_offset)893 void ImageWriter::CalculateNewObjectOffsets(size_t oat_loaded_size, size_t oat_data_offset) {
894   CHECK_NE(0U, oat_loaded_size);
895   Thread* self = Thread::Current();
896   StackHandleScope<1> hs(self);
897   Handle<ObjectArray<Object>> image_roots(hs.NewHandle(CreateImageRoots()));
898 
899   gc::Heap* heap = Runtime::Current()->GetHeap();
900   DCHECK_EQ(0U, image_end_);
901 
902   // Leave space for the header, but do not write it yet, we need to
903   // know where image_roots is going to end up
904   image_end_ += RoundUp(sizeof(ImageHeader), kObjectAlignment);  // 64-bit-alignment
905 
906   {
907     WriterMutexLock mu(self, *Locks::heap_bitmap_lock_);
908     // TODO: Image spaces only?
909     const char* old = self->StartAssertNoThreadSuspension("ImageWriter");
910     DCHECK_LT(image_end_, image_->Size());
911     image_objects_offset_begin_ = image_end_;
912     // Clear any pre-existing monitors which may have been in the monitor words, assign bin slots.
913     heap->VisitObjects(WalkFieldsCallback, this);
914     // Transform each object's bin slot into an offset which will be used to do the final copy.
915     heap->VisitObjects(UnbinObjectsIntoOffsetCallback, this);
916     DCHECK(saved_hashes_map_.empty());  // All binslot hashes should've been put into vector by now.
917     self->EndAssertNoThreadSuspension(old);
918   }
919 
920   DCHECK_GT(image_end_, GetBinSizeSum());
921 
922   if (kIsDebugBuild) {
923     LOG(INFO) << "Bin summary (total size: " << GetBinSizeSum() << "): ";
924     for (size_t bin = 0; bin < kBinSize; ++bin) {
925       LOG(INFO) << "  bin# " << bin << ", number objects: " << bin_slot_count_[bin] << ", "
926                 << " total byte size: " << bin_slot_sizes_[bin];
927     }
928   }
929 
930   const byte* oat_file_begin = image_begin_ + RoundUp(image_end_, kPageSize);
931   const byte* oat_file_end = oat_file_begin + oat_loaded_size;
932   oat_data_begin_ = oat_file_begin + oat_data_offset;
933   const byte* oat_data_end = oat_data_begin_ + oat_file_->Size();
934 
935   // Return to write header at start of image with future location of image_roots. At this point,
936   // image_end_ is the size of the image (excluding bitmaps).
937   const size_t heap_bytes_per_bitmap_byte = kBitsPerByte * kObjectAlignment;
938   const size_t bitmap_bytes = RoundUp(image_end_, heap_bytes_per_bitmap_byte) /
939       heap_bytes_per_bitmap_byte;
940   ImageHeader image_header(PointerToLowMemUInt32(image_begin_),
941                            static_cast<uint32_t>(image_end_),
942                            RoundUp(image_end_, kPageSize),
943                            RoundUp(bitmap_bytes, kPageSize),
944                            PointerToLowMemUInt32(GetImageAddress(image_roots.Get())),
945                            oat_file_->GetOatHeader().GetChecksum(),
946                            PointerToLowMemUInt32(oat_file_begin),
947                            PointerToLowMemUInt32(oat_data_begin_),
948                            PointerToLowMemUInt32(oat_data_end),
949                            PointerToLowMemUInt32(oat_file_end),
950                            compile_pic_);
951   memcpy(image_->Begin(), &image_header, sizeof(image_header));
952 
953   // Note that image_end_ is left at end of used space
954 }
955 
CopyAndFixupObjects()956 void ImageWriter::CopyAndFixupObjects() {
957   Thread* self = Thread::Current();
958   const char* old_cause = self->StartAssertNoThreadSuspension("ImageWriter");
959   gc::Heap* heap = Runtime::Current()->GetHeap();
960   // TODO: heap validation can't handle this fix up pass
961   heap->DisableObjectValidation();
962   // TODO: Image spaces only?
963   WriterMutexLock mu(self, *Locks::heap_bitmap_lock_);
964   heap->VisitObjects(CopyAndFixupObjectsCallback, this);
965   // Fix up the object previously had hash codes.
966   for (const std::pair<mirror::Object*, uint32_t>& hash_pair : saved_hashes_) {
967     hash_pair.first->SetLockWord(LockWord::FromHashCode(hash_pair.second), false);
968   }
969   saved_hashes_.clear();
970   self->EndAssertNoThreadSuspension(old_cause);
971 }
972 
CopyAndFixupObjectsCallback(Object * obj,void * arg)973 void ImageWriter::CopyAndFixupObjectsCallback(Object* obj, void* arg) {
974   DCHECK(obj != nullptr);
975   DCHECK(arg != nullptr);
976   ImageWriter* image_writer = reinterpret_cast<ImageWriter*>(arg);
977   // see GetLocalAddress for similar computation
978   size_t offset = image_writer->GetImageOffset(obj);
979   byte* dst = image_writer->image_->Begin() + offset;
980   const byte* src = reinterpret_cast<const byte*>(obj);
981   size_t n;
982   if (obj->IsArtMethod()) {
983     // Size without pointer fields since we don't want to overrun the buffer if target art method
984     // is 32 bits but source is 64 bits.
985     n = mirror::ArtMethod::SizeWithoutPointerFields(sizeof(void*));
986   } else {
987     n = obj->SizeOf();
988   }
989   DCHECK_LT(offset + n, image_writer->image_->Size());
990   memcpy(dst, src, n);
991   Object* copy = reinterpret_cast<Object*>(dst);
992   // Write in a hash code of objects which have inflated monitors or a hash code in their monitor
993   // word.
994   copy->SetLockWord(LockWord(), false);
995   image_writer->FixupObject(obj, copy);
996 }
997 
998 // Rewrite all the references in the copied object to point to their image address equivalent
999 class FixupVisitor {
1000  public:
FixupVisitor(ImageWriter * image_writer,Object * copy)1001   FixupVisitor(ImageWriter* image_writer, Object* copy) : image_writer_(image_writer), copy_(copy) {
1002   }
1003 
operator ()(Object * obj,MemberOffset offset,bool) const1004   void operator()(Object* obj, MemberOffset offset, bool /*is_static*/) const
1005       EXCLUSIVE_LOCKS_REQUIRED(Locks::mutator_lock_, Locks::heap_bitmap_lock_) {
1006     Object* ref = obj->GetFieldObject<Object, kVerifyNone>(offset);
1007     // Use SetFieldObjectWithoutWriteBarrier to avoid card marking since we are writing to the
1008     // image.
1009     copy_->SetFieldObjectWithoutWriteBarrier<false, true, kVerifyNone>(
1010         offset, image_writer_->GetImageAddress(ref));
1011   }
1012 
1013   // java.lang.ref.Reference visitor.
operator ()(mirror::Class *,mirror::Reference * ref) const1014   void operator()(mirror::Class* /*klass*/, mirror::Reference* ref) const
1015       SHARED_LOCKS_REQUIRED(Locks::mutator_lock_)
1016       EXCLUSIVE_LOCKS_REQUIRED(Locks::heap_bitmap_lock_) {
1017     copy_->SetFieldObjectWithoutWriteBarrier<false, true, kVerifyNone>(
1018         mirror::Reference::ReferentOffset(), image_writer_->GetImageAddress(ref->GetReferent()));
1019   }
1020 
1021  protected:
1022   ImageWriter* const image_writer_;
1023   mirror::Object* const copy_;
1024 };
1025 
1026 class FixupClassVisitor FINAL : public FixupVisitor {
1027  public:
FixupClassVisitor(ImageWriter * image_writer,Object * copy)1028   FixupClassVisitor(ImageWriter* image_writer, Object* copy) : FixupVisitor(image_writer, copy) {
1029   }
1030 
operator ()(Object * obj,MemberOffset offset,bool) const1031   void operator()(Object* obj, MemberOffset offset, bool /*is_static*/) const
1032       EXCLUSIVE_LOCKS_REQUIRED(Locks::mutator_lock_, Locks::heap_bitmap_lock_) {
1033     DCHECK(obj->IsClass());
1034     FixupVisitor::operator()(obj, offset, /*is_static*/false);
1035 
1036     // TODO: Remove dead code
1037     if (offset.Uint32Value() < mirror::Class::EmbeddedVTableOffset().Uint32Value()) {
1038       return;
1039     }
1040   }
1041 
operator ()(mirror::Class *,mirror::Reference * ref) const1042   void operator()(mirror::Class* /*klass*/, mirror::Reference* ref) const
1043       SHARED_LOCKS_REQUIRED(Locks::mutator_lock_)
1044       EXCLUSIVE_LOCKS_REQUIRED(Locks::heap_bitmap_lock_) {
1045     LOG(FATAL) << "Reference not expected here.";
1046   }
1047 };
1048 
FixupObject(Object * orig,Object * copy)1049 void ImageWriter::FixupObject(Object* orig, Object* copy) {
1050   DCHECK(orig != nullptr);
1051   DCHECK(copy != nullptr);
1052   if (kUseBakerOrBrooksReadBarrier) {
1053     orig->AssertReadBarrierPointer();
1054     if (kUseBrooksReadBarrier) {
1055       // Note the address 'copy' isn't the same as the image address of 'orig'.
1056       copy->SetReadBarrierPointer(GetImageAddress(orig));
1057       DCHECK_EQ(copy->GetReadBarrierPointer(), GetImageAddress(orig));
1058     }
1059   }
1060   if (orig->IsClass() && orig->AsClass()->ShouldHaveEmbeddedImtAndVTable()) {
1061     FixupClassVisitor visitor(this, copy);
1062     orig->VisitReferences<true /*visit class*/>(visitor, visitor);
1063   } else {
1064     FixupVisitor visitor(this, copy);
1065     orig->VisitReferences<true /*visit class*/>(visitor, visitor);
1066   }
1067   if (orig->IsArtMethod<kVerifyNone>()) {
1068     FixupMethod(orig->AsArtMethod<kVerifyNone>(), down_cast<ArtMethod*>(copy));
1069   } else if (orig->IsClass() && orig->AsClass()->IsArtMethodClass()) {
1070     // Set the right size for the target.
1071     size_t size = mirror::ArtMethod::InstanceSize(target_ptr_size_);
1072     down_cast<mirror::Class*>(copy)->SetObjectSizeWithoutChecks(size);
1073   }
1074 }
1075 
GetQuickCode(mirror::ArtMethod * method,bool * quick_is_interpreted)1076 const byte* ImageWriter::GetQuickCode(mirror::ArtMethod* method, bool* quick_is_interpreted) {
1077   DCHECK(!method->IsResolutionMethod() && !method->IsImtConflictMethod() &&
1078          !method->IsImtUnimplementedMethod() && !method->IsAbstract()) << PrettyMethod(method);
1079 
1080   // Use original code if it exists. Otherwise, set the code pointer to the resolution
1081   // trampoline.
1082 
1083   // Quick entrypoint:
1084   const byte* quick_code = GetOatAddress(method->GetQuickOatCodeOffset());
1085   *quick_is_interpreted = false;
1086   if (quick_code != nullptr &&
1087       (!method->IsStatic() || method->IsConstructor() || method->GetDeclaringClass()->IsInitialized())) {
1088     // We have code for a non-static or initialized method, just use the code.
1089   } else if (quick_code == nullptr && method->IsNative() &&
1090       (!method->IsStatic() || method->GetDeclaringClass()->IsInitialized())) {
1091     // Non-static or initialized native method missing compiled code, use generic JNI version.
1092     quick_code = GetOatAddress(quick_generic_jni_trampoline_offset_);
1093   } else if (quick_code == nullptr && !method->IsNative()) {
1094     // We don't have code at all for a non-native method, use the interpreter.
1095     quick_code = GetOatAddress(quick_to_interpreter_bridge_offset_);
1096     *quick_is_interpreted = true;
1097   } else {
1098     CHECK(!method->GetDeclaringClass()->IsInitialized());
1099     // We have code for a static method, but need to go through the resolution stub for class
1100     // initialization.
1101     quick_code = GetOatAddress(quick_resolution_trampoline_offset_);
1102   }
1103   return quick_code;
1104 }
1105 
GetQuickEntryPoint(mirror::ArtMethod * method)1106 const byte* ImageWriter::GetQuickEntryPoint(mirror::ArtMethod* method) {
1107   // Calculate the quick entry point following the same logic as FixupMethod() below.
1108   // The resolution method has a special trampoline to call.
1109   Runtime* runtime = Runtime::Current();
1110   if (UNLIKELY(method == runtime->GetResolutionMethod())) {
1111     return GetOatAddress(quick_resolution_trampoline_offset_);
1112   } else if (UNLIKELY(method == runtime->GetImtConflictMethod() ||
1113                       method == runtime->GetImtUnimplementedMethod())) {
1114     return GetOatAddress(quick_imt_conflict_trampoline_offset_);
1115   } else {
1116     // We assume all methods have code. If they don't currently then we set them to the use the
1117     // resolution trampoline. Abstract methods never have code and so we need to make sure their
1118     // use results in an AbstractMethodError. We use the interpreter to achieve this.
1119     if (UNLIKELY(method->IsAbstract())) {
1120       return GetOatAddress(quick_to_interpreter_bridge_offset_);
1121     } else {
1122       bool quick_is_interpreted;
1123       return GetQuickCode(method, &quick_is_interpreted);
1124     }
1125   }
1126 }
1127 
FixupMethod(ArtMethod * orig,ArtMethod * copy)1128 void ImageWriter::FixupMethod(ArtMethod* orig, ArtMethod* copy) {
1129   // OatWriter replaces the code_ with an offset value. Here we re-adjust to a pointer relative to
1130   // oat_begin_
1131   // For 64 bit targets we need to repack the current runtime pointer sized fields to the right
1132   // locations.
1133   // Copy all of the fields from the runtime methods to the target methods first since we did a
1134   // bytewise copy earlier.
1135 #if defined(ART_USE_PORTABLE_COMPILER)
1136   copy->SetEntryPointFromPortableCompiledCodePtrSize<kVerifyNone>(
1137       orig->GetEntryPointFromPortableCompiledCode(), target_ptr_size_);
1138 #endif
1139   copy->SetEntryPointFromInterpreterPtrSize<kVerifyNone>(orig->GetEntryPointFromInterpreter(),
1140                                                          target_ptr_size_);
1141   copy->SetEntryPointFromJniPtrSize<kVerifyNone>(orig->GetEntryPointFromJni(), target_ptr_size_);
1142   copy->SetEntryPointFromQuickCompiledCodePtrSize<kVerifyNone>(
1143       orig->GetEntryPointFromQuickCompiledCode(), target_ptr_size_);
1144 
1145   // The resolution method has a special trampoline to call.
1146   Runtime* runtime = Runtime::Current();
1147   if (UNLIKELY(orig == runtime->GetResolutionMethod())) {
1148 #if defined(ART_USE_PORTABLE_COMPILER)
1149     copy->SetEntryPointFromPortableCompiledCodePtrSize<kVerifyNone>(
1150         GetOatAddress(portable_resolution_trampoline_offset_), target_ptr_size_);
1151 #endif
1152     copy->SetEntryPointFromQuickCompiledCodePtrSize<kVerifyNone>(
1153         GetOatAddress(quick_resolution_trampoline_offset_), target_ptr_size_);
1154   } else if (UNLIKELY(orig == runtime->GetImtConflictMethod() ||
1155                       orig == runtime->GetImtUnimplementedMethod())) {
1156 #if defined(ART_USE_PORTABLE_COMPILER)
1157     copy->SetEntryPointFromPortableCompiledCode<kVerifyNone>(
1158         GetOatAddress(portable_imt_conflict_trampoline_offset_), target_ptr_size_);
1159 #endif
1160     copy->SetEntryPointFromQuickCompiledCodePtrSize<kVerifyNone>(
1161         GetOatAddress(quick_imt_conflict_trampoline_offset_), target_ptr_size_);
1162   } else {
1163     // We assume all methods have code. If they don't currently then we set them to the use the
1164     // resolution trampoline. Abstract methods never have code and so we need to make sure their
1165     // use results in an AbstractMethodError. We use the interpreter to achieve this.
1166     if (UNLIKELY(orig->IsAbstract())) {
1167 #if defined(ART_USE_PORTABLE_COMPILER)
1168       copy->SetEntryPointFromPortableCompiledCode<kVerifyNone>(
1169           GetOatAddress(portable_to_interpreter_bridge_offset_), target_ptr_size_);
1170 #endif
1171       copy->SetEntryPointFromQuickCompiledCodePtrSize<kVerifyNone>(
1172           GetOatAddress(quick_to_interpreter_bridge_offset_), target_ptr_size_);
1173       copy->SetEntryPointFromInterpreterPtrSize<kVerifyNone>(
1174           reinterpret_cast<EntryPointFromInterpreter*>(const_cast<byte*>(
1175               GetOatAddress(interpreter_to_interpreter_bridge_offset_))), target_ptr_size_);
1176     } else {
1177       bool quick_is_interpreted;
1178       const byte* quick_code = GetQuickCode(orig, &quick_is_interpreted);
1179       copy->SetEntryPointFromQuickCompiledCodePtrSize<kVerifyNone>(quick_code, target_ptr_size_);
1180 
1181       // Portable entrypoint:
1182       bool portable_is_interpreted = false;
1183 #if defined(ART_USE_PORTABLE_COMPILER)
1184       const byte* portable_code = GetOatAddress(orig->GetPortableOatCodeOffset());
1185       if (portable_code != nullptr && (!orig->IsStatic() || orig->IsConstructor() ||
1186           orig->GetDeclaringClass()->IsInitialized())) {
1187         // We have code for a non-static or initialized method, just use the code.
1188       } else if (portable_code == nullptr && orig->IsNative() &&
1189           (!orig->IsStatic() || orig->GetDeclaringClass()->IsInitialized())) {
1190         // Non-static or initialized native method missing compiled code, use generic JNI version.
1191         // TODO: generic JNI support for LLVM.
1192         portable_code = GetOatAddress(portable_resolution_trampoline_offset_);
1193       } else if (portable_code == nullptr && !orig->IsNative()) {
1194         // We don't have code at all for a non-native method, use the interpreter.
1195         portable_code = GetOatAddress(portable_to_interpreter_bridge_offset_);
1196         portable_is_interpreted = true;
1197       } else {
1198         CHECK(!orig->GetDeclaringClass()->IsInitialized());
1199         // We have code for a static method, but need to go through the resolution stub for class
1200         // initialization.
1201         portable_code = GetOatAddress(portable_resolution_trampoline_offset_);
1202       }
1203       copy->SetEntryPointFromPortableCompiledCodePtrSize<kVerifyNone>(
1204           portable_code, target_ptr_size_);
1205 #endif
1206       // JNI entrypoint:
1207       if (orig->IsNative()) {
1208         // The native method's pointer is set to a stub to lookup via dlsym.
1209         // Note this is not the code_ pointer, that is handled above.
1210         copy->SetEntryPointFromJniPtrSize<kVerifyNone>(GetOatAddress(jni_dlsym_lookup_offset_),
1211                                                        target_ptr_size_);
1212       }
1213 
1214       // Interpreter entrypoint:
1215       // Set the interpreter entrypoint depending on whether there is compiled code or not.
1216       uint32_t interpreter_code = (quick_is_interpreted && portable_is_interpreted)
1217           ? interpreter_to_interpreter_bridge_offset_
1218           : interpreter_to_compiled_code_bridge_offset_;
1219       EntryPointFromInterpreter* interpreter_entrypoint =
1220           reinterpret_cast<EntryPointFromInterpreter*>(
1221               const_cast<byte*>(GetOatAddress(interpreter_code)));
1222       copy->SetEntryPointFromInterpreterPtrSize<kVerifyNone>(
1223           interpreter_entrypoint, target_ptr_size_);
1224     }
1225   }
1226 }
1227 
GetOatHeaderFromElf(ElfFile * elf)1228 static OatHeader* GetOatHeaderFromElf(ElfFile* elf) {
1229   Elf32_Shdr* data_sec = elf->FindSectionByName(".rodata");
1230   if (data_sec == nullptr) {
1231     return nullptr;
1232   }
1233   return reinterpret_cast<OatHeader*>(elf->Begin() + data_sec->sh_offset);
1234 }
1235 
PatchOatCodeAndMethods(File * elf_file)1236 void ImageWriter::PatchOatCodeAndMethods(File* elf_file) {
1237   std::string error_msg;
1238   std::unique_ptr<ElfFile> elf(ElfFile::Open(elf_file, PROT_READ|PROT_WRITE,
1239                                              MAP_SHARED, &error_msg));
1240   if (elf.get() == nullptr) {
1241     LOG(FATAL) << "Unable patch oat file: " << error_msg;
1242     return;
1243   }
1244   if (!ElfPatcher::Patch(&compiler_driver_, elf.get(), oat_file_,
1245                          reinterpret_cast<uintptr_t>(oat_data_begin_),
1246                          GetImageAddressCallback, reinterpret_cast<void*>(this),
1247                          &error_msg)) {
1248     LOG(FATAL) << "unable to patch oat file: " << error_msg;
1249     return;
1250   }
1251   OatHeader* oat_header = GetOatHeaderFromElf(elf.get());
1252   CHECK(oat_header != nullptr);
1253   CHECK(oat_header->IsValid());
1254 
1255   ImageHeader* image_header = reinterpret_cast<ImageHeader*>(image_->Begin());
1256   image_header->SetOatChecksum(oat_header->GetChecksum());
1257 }
1258 
GetBinSizeSum(ImageWriter::Bin up_to) const1259 size_t ImageWriter::GetBinSizeSum(ImageWriter::Bin up_to) const {
1260   DCHECK_LE(up_to, kBinSize);
1261   return std::accumulate(&bin_slot_sizes_[0], &bin_slot_sizes_[up_to], /*init*/0);
1262 }
1263 
BinSlot(uint32_t lockword)1264 ImageWriter::BinSlot::BinSlot(uint32_t lockword) : lockword_(lockword) {
1265   // These values may need to get updated if more bins are added to the enum Bin
1266   static_assert(kBinBits == 3, "wrong number of bin bits");
1267   static_assert(kBinShift == 29, "wrong number of shift");
1268   static_assert(sizeof(BinSlot) == sizeof(LockWord), "BinSlot/LockWord must have equal sizes");
1269 
1270   DCHECK_LT(GetBin(), kBinSize);
1271   DCHECK_ALIGNED(GetIndex(), kObjectAlignment);
1272 }
1273 
BinSlot(Bin bin,uint32_t index)1274 ImageWriter::BinSlot::BinSlot(Bin bin, uint32_t index)
1275     : BinSlot(index | (static_cast<uint32_t>(bin) << kBinShift)) {
1276   DCHECK_EQ(index, GetIndex());
1277 }
1278 
GetBin() const1279 ImageWriter::Bin ImageWriter::BinSlot::GetBin() const {
1280   return static_cast<Bin>((lockword_ & kBinMask) >> kBinShift);
1281 }
1282 
GetIndex() const1283 uint32_t ImageWriter::BinSlot::GetIndex() const {
1284   return lockword_ & ~kBinMask;
1285 }
1286 
1287 }  // namespace art
1288