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      1 // Copyright 2016 the V8 project authors. All rights reserved.
      2 // Use of this source code is governed by a BSD-style license that can be
      3 // found in the LICENSE file.
      4 
      5 #include "src/snapshot/code-serializer.h"
      6 
      7 #include "src/code-stubs.h"
      8 #include "src/log.h"
      9 #include "src/macro-assembler.h"
     10 #include "src/snapshot/deserializer.h"
     11 #include "src/version.h"
     12 
     13 namespace v8 {
     14 namespace internal {
     15 
     16 ScriptData* CodeSerializer::Serialize(Isolate* isolate,
     17                                       Handle<SharedFunctionInfo> info,
     18                                       Handle<String> source) {
     19   base::ElapsedTimer timer;
     20   if (FLAG_profile_deserialization) timer.Start();
     21   if (FLAG_trace_serializer) {
     22     PrintF("[Serializing from");
     23     Object* script = info->script();
     24     if (script->IsScript()) Script::cast(script)->name()->ShortPrint();
     25     PrintF("]\n");
     26   }
     27 
     28   // Serialize code object.
     29   CodeSerializer cs(isolate, *source);
     30   DisallowHeapAllocation no_gc;
     31   Object** location = Handle<Object>::cast(info).location();
     32   cs.VisitPointer(location);
     33   cs.SerializeDeferredObjects();
     34   cs.Pad();
     35 
     36   SerializedCodeData data(cs.sink()->data(), &cs);
     37   ScriptData* script_data = data.GetScriptData();
     38 
     39   if (FLAG_profile_deserialization) {
     40     double ms = timer.Elapsed().InMillisecondsF();
     41     int length = script_data->length();
     42     PrintF("[Serializing to %d bytes took %0.3f ms]\n", length, ms);
     43   }
     44 
     45   return script_data;
     46 }
     47 
     48 void CodeSerializer::SerializeObject(HeapObject* obj, HowToCode how_to_code,
     49                                      WhereToPoint where_to_point, int skip) {
     50   if (SerializeHotObject(obj, how_to_code, where_to_point, skip)) return;
     51 
     52   int root_index = root_index_map_.Lookup(obj);
     53   if (root_index != RootIndexMap::kInvalidRootIndex) {
     54     PutRoot(root_index, obj, how_to_code, where_to_point, skip);
     55     return;
     56   }
     57 
     58   if (SerializeBackReference(obj, how_to_code, where_to_point, skip)) return;
     59 
     60   FlushSkip(skip);
     61 
     62   if (obj->IsCode()) {
     63     Code* code_object = Code::cast(obj);
     64     switch (code_object->kind()) {
     65       case Code::OPTIMIZED_FUNCTION:  // No optimized code compiled yet.
     66       case Code::HANDLER:             // No handlers patched in yet.
     67       case Code::REGEXP:              // No regexp literals initialized yet.
     68       case Code::NUMBER_OF_KINDS:     // Pseudo enum value.
     69       case Code::BYTECODE_HANDLER:    // No direct references to handlers.
     70         CHECK(false);
     71       case Code::BUILTIN:
     72         SerializeBuiltin(code_object->builtin_index(), how_to_code,
     73                          where_to_point);
     74         return;
     75       case Code::STUB:
     76 #define IC_KIND_CASE(KIND) case Code::KIND:
     77         IC_KIND_LIST(IC_KIND_CASE)
     78 #undef IC_KIND_CASE
     79         SerializeCodeStub(code_object, how_to_code, where_to_point);
     80         return;
     81       case Code::FUNCTION:
     82         DCHECK(code_object->has_reloc_info_for_serialization());
     83         SerializeGeneric(code_object, how_to_code, where_to_point);
     84         return;
     85       case Code::WASM_FUNCTION:
     86       case Code::WASM_TO_JS_FUNCTION:
     87       case Code::JS_TO_WASM_FUNCTION:
     88         UNREACHABLE();
     89     }
     90     UNREACHABLE();
     91   }
     92 
     93   // Past this point we should not see any (context-specific) maps anymore.
     94   CHECK(!obj->IsMap());
     95   // There should be no references to the global object embedded.
     96   CHECK(!obj->IsJSGlobalProxy() && !obj->IsJSGlobalObject());
     97   // There should be no hash table embedded. They would require rehashing.
     98   CHECK(!obj->IsHashTable());
     99   // We expect no instantiated function objects or contexts.
    100   CHECK(!obj->IsJSFunction() && !obj->IsContext());
    101 
    102   SerializeGeneric(obj, how_to_code, where_to_point);
    103 }
    104 
    105 void CodeSerializer::SerializeGeneric(HeapObject* heap_object,
    106                                       HowToCode how_to_code,
    107                                       WhereToPoint where_to_point) {
    108   // Object has not yet been serialized.  Serialize it here.
    109   ObjectSerializer serializer(this, heap_object, &sink_, how_to_code,
    110                               where_to_point);
    111   serializer.Serialize();
    112 }
    113 
    114 void CodeSerializer::SerializeBuiltin(int builtin_index, HowToCode how_to_code,
    115                                       WhereToPoint where_to_point) {
    116   DCHECK((how_to_code == kPlain && where_to_point == kStartOfObject) ||
    117          (how_to_code == kPlain && where_to_point == kInnerPointer) ||
    118          (how_to_code == kFromCode && where_to_point == kInnerPointer));
    119   DCHECK_LT(builtin_index, Builtins::builtin_count);
    120   DCHECK_LE(0, builtin_index);
    121 
    122   if (FLAG_trace_serializer) {
    123     PrintF(" Encoding builtin: %s\n",
    124            isolate()->builtins()->name(builtin_index));
    125   }
    126 
    127   sink_.Put(kBuiltin + how_to_code + where_to_point, "Builtin");
    128   sink_.PutInt(builtin_index, "builtin_index");
    129 }
    130 
    131 void CodeSerializer::SerializeCodeStub(Code* code_stub, HowToCode how_to_code,
    132                                        WhereToPoint where_to_point) {
    133   // We only arrive here if we have not encountered this code stub before.
    134   DCHECK(!reference_map()->Lookup(code_stub).is_valid());
    135   uint32_t stub_key = code_stub->stub_key();
    136   DCHECK(CodeStub::MajorKeyFromKey(stub_key) != CodeStub::NoCache);
    137   DCHECK(!CodeStub::GetCode(isolate(), stub_key).is_null());
    138   stub_keys_.Add(stub_key);
    139 
    140   SerializerReference reference =
    141       reference_map()->AddAttachedReference(code_stub);
    142   if (FLAG_trace_serializer) {
    143     PrintF(" Encoding code stub %s as attached reference %d\n",
    144            CodeStub::MajorName(CodeStub::MajorKeyFromKey(stub_key)),
    145            reference.attached_reference_index());
    146   }
    147   PutAttachedReference(reference, how_to_code, where_to_point);
    148 }
    149 
    150 MaybeHandle<SharedFunctionInfo> CodeSerializer::Deserialize(
    151     Isolate* isolate, ScriptData* cached_data, Handle<String> source) {
    152   base::ElapsedTimer timer;
    153   if (FLAG_profile_deserialization) timer.Start();
    154 
    155   HandleScope scope(isolate);
    156 
    157   base::SmartPointer<SerializedCodeData> scd(
    158       SerializedCodeData::FromCachedData(isolate, cached_data, *source));
    159   if (scd.is_empty()) {
    160     if (FLAG_profile_deserialization) PrintF("[Cached code failed check]\n");
    161     DCHECK(cached_data->rejected());
    162     return MaybeHandle<SharedFunctionInfo>();
    163   }
    164 
    165   Deserializer deserializer(scd.get());
    166   deserializer.AddAttachedObject(source);
    167   Vector<const uint32_t> code_stub_keys = scd->CodeStubKeys();
    168   for (int i = 0; i < code_stub_keys.length(); i++) {
    169     deserializer.AddAttachedObject(
    170         CodeStub::GetCode(isolate, code_stub_keys[i]).ToHandleChecked());
    171   }
    172 
    173   // Deserialize.
    174   Handle<SharedFunctionInfo> result;
    175   if (!deserializer.DeserializeCode(isolate).ToHandle(&result)) {
    176     // Deserializing may fail if the reservations cannot be fulfilled.
    177     if (FLAG_profile_deserialization) PrintF("[Deserializing failed]\n");
    178     return MaybeHandle<SharedFunctionInfo>();
    179   }
    180 
    181   if (FLAG_profile_deserialization) {
    182     double ms = timer.Elapsed().InMillisecondsF();
    183     int length = cached_data->length();
    184     PrintF("[Deserializing from %d bytes took %0.3f ms]\n", length, ms);
    185   }
    186   result->set_deserialized(true);
    187 
    188   if (isolate->logger()->is_logging_code_events() || isolate->is_profiling()) {
    189     String* name = isolate->heap()->empty_string();
    190     if (result->script()->IsScript()) {
    191       Script* script = Script::cast(result->script());
    192       if (script->name()->IsString()) name = String::cast(script->name());
    193     }
    194     PROFILE(isolate, CodeCreateEvent(CodeEventListener::SCRIPT_TAG,
    195                                      result->abstract_code(), *result, name));
    196   }
    197   return scope.CloseAndEscape(result);
    198 }
    199 
    200 class Checksum {
    201  public:
    202   explicit Checksum(Vector<const byte> payload) {
    203 #ifdef MEMORY_SANITIZER
    204     // Computing the checksum includes padding bytes for objects like strings.
    205     // Mark every object as initialized in the code serializer.
    206     MSAN_MEMORY_IS_INITIALIZED(payload.start(), payload.length());
    207 #endif  // MEMORY_SANITIZER
    208     // Fletcher's checksum. Modified to reduce 64-bit sums to 32-bit.
    209     uintptr_t a = 1;
    210     uintptr_t b = 0;
    211     const uintptr_t* cur = reinterpret_cast<const uintptr_t*>(payload.start());
    212     DCHECK(IsAligned(payload.length(), kIntptrSize));
    213     const uintptr_t* end = cur + payload.length() / kIntptrSize;
    214     while (cur < end) {
    215       // Unsigned overflow expected and intended.
    216       a += *cur++;
    217       b += a;
    218     }
    219 #if V8_HOST_ARCH_64_BIT
    220     a ^= a >> 32;
    221     b ^= b >> 32;
    222 #endif  // V8_HOST_ARCH_64_BIT
    223     a_ = static_cast<uint32_t>(a);
    224     b_ = static_cast<uint32_t>(b);
    225   }
    226 
    227   bool Check(uint32_t a, uint32_t b) const { return a == a_ && b == b_; }
    228 
    229   uint32_t a() const { return a_; }
    230   uint32_t b() const { return b_; }
    231 
    232  private:
    233   uint32_t a_;
    234   uint32_t b_;
    235 
    236   DISALLOW_COPY_AND_ASSIGN(Checksum);
    237 };
    238 
    239 SerializedCodeData::SerializedCodeData(const List<byte>* payload,
    240                                        const CodeSerializer* cs) {
    241   DisallowHeapAllocation no_gc;
    242   const List<uint32_t>* stub_keys = cs->stub_keys();
    243 
    244   List<Reservation> reservations;
    245   cs->EncodeReservations(&reservations);
    246 
    247   // Calculate sizes.
    248   int reservation_size = reservations.length() * kInt32Size;
    249   int num_stub_keys = stub_keys->length();
    250   int stub_keys_size = stub_keys->length() * kInt32Size;
    251   int payload_offset = kHeaderSize + reservation_size + stub_keys_size;
    252   int padded_payload_offset = POINTER_SIZE_ALIGN(payload_offset);
    253   int size = padded_payload_offset + payload->length();
    254 
    255   // Allocate backing store and create result data.
    256   AllocateData(size);
    257 
    258   // Set header values.
    259   SetMagicNumber(cs->isolate());
    260   SetHeaderValue(kVersionHashOffset, Version::Hash());
    261   SetHeaderValue(kSourceHashOffset, SourceHash(cs->source()));
    262   SetHeaderValue(kCpuFeaturesOffset,
    263                  static_cast<uint32_t>(CpuFeatures::SupportedFeatures()));
    264   SetHeaderValue(kFlagHashOffset, FlagList::Hash());
    265   SetHeaderValue(kNumReservationsOffset, reservations.length());
    266   SetHeaderValue(kNumCodeStubKeysOffset, num_stub_keys);
    267   SetHeaderValue(kPayloadLengthOffset, payload->length());
    268 
    269   Checksum checksum(payload->ToConstVector());
    270   SetHeaderValue(kChecksum1Offset, checksum.a());
    271   SetHeaderValue(kChecksum2Offset, checksum.b());
    272 
    273   // Copy reservation chunk sizes.
    274   CopyBytes(data_ + kHeaderSize, reinterpret_cast<byte*>(reservations.begin()),
    275             reservation_size);
    276 
    277   // Copy code stub keys.
    278   CopyBytes(data_ + kHeaderSize + reservation_size,
    279             reinterpret_cast<byte*>(stub_keys->begin()), stub_keys_size);
    280 
    281   memset(data_ + payload_offset, 0, padded_payload_offset - payload_offset);
    282 
    283   // Copy serialized data.
    284   CopyBytes(data_ + padded_payload_offset, payload->begin(),
    285             static_cast<size_t>(payload->length()));
    286 }
    287 
    288 SerializedCodeData::SanityCheckResult SerializedCodeData::SanityCheck(
    289     Isolate* isolate, String* source) const {
    290   uint32_t magic_number = GetMagicNumber();
    291   if (magic_number != ComputeMagicNumber(isolate)) return MAGIC_NUMBER_MISMATCH;
    292   uint32_t version_hash = GetHeaderValue(kVersionHashOffset);
    293   uint32_t source_hash = GetHeaderValue(kSourceHashOffset);
    294   uint32_t cpu_features = GetHeaderValue(kCpuFeaturesOffset);
    295   uint32_t flags_hash = GetHeaderValue(kFlagHashOffset);
    296   uint32_t c1 = GetHeaderValue(kChecksum1Offset);
    297   uint32_t c2 = GetHeaderValue(kChecksum2Offset);
    298   if (version_hash != Version::Hash()) return VERSION_MISMATCH;
    299   if (source_hash != SourceHash(source)) return SOURCE_MISMATCH;
    300   if (cpu_features != static_cast<uint32_t>(CpuFeatures::SupportedFeatures())) {
    301     return CPU_FEATURES_MISMATCH;
    302   }
    303   if (flags_hash != FlagList::Hash()) return FLAGS_MISMATCH;
    304   if (!Checksum(Payload()).Check(c1, c2)) return CHECKSUM_MISMATCH;
    305   return CHECK_SUCCESS;
    306 }
    307 
    308 uint32_t SerializedCodeData::SourceHash(String* source) const {
    309   return source->length();
    310 }
    311 
    312 // Return ScriptData object and relinquish ownership over it to the caller.
    313 ScriptData* SerializedCodeData::GetScriptData() {
    314   DCHECK(owns_data_);
    315   ScriptData* result = new ScriptData(data_, size_);
    316   result->AcquireDataOwnership();
    317   owns_data_ = false;
    318   data_ = NULL;
    319   return result;
    320 }
    321 
    322 Vector<const SerializedData::Reservation> SerializedCodeData::Reservations()
    323     const {
    324   return Vector<const Reservation>(
    325       reinterpret_cast<const Reservation*>(data_ + kHeaderSize),
    326       GetHeaderValue(kNumReservationsOffset));
    327 }
    328 
    329 Vector<const byte> SerializedCodeData::Payload() const {
    330   int reservations_size = GetHeaderValue(kNumReservationsOffset) * kInt32Size;
    331   int code_stubs_size = GetHeaderValue(kNumCodeStubKeysOffset) * kInt32Size;
    332   int payload_offset = kHeaderSize + reservations_size + code_stubs_size;
    333   int padded_payload_offset = POINTER_SIZE_ALIGN(payload_offset);
    334   const byte* payload = data_ + padded_payload_offset;
    335   DCHECK(IsAligned(reinterpret_cast<intptr_t>(payload), kPointerAlignment));
    336   int length = GetHeaderValue(kPayloadLengthOffset);
    337   DCHECK_EQ(data_ + size_, payload + length);
    338   return Vector<const byte>(payload, length);
    339 }
    340 
    341 Vector<const uint32_t> SerializedCodeData::CodeStubKeys() const {
    342   int reservations_size = GetHeaderValue(kNumReservationsOffset) * kInt32Size;
    343   const byte* start = data_ + kHeaderSize + reservations_size;
    344   return Vector<const uint32_t>(reinterpret_cast<const uint32_t*>(start),
    345                                 GetHeaderValue(kNumCodeStubKeysOffset));
    346 }
    347 
    348 SerializedCodeData::SerializedCodeData(ScriptData* data)
    349     : SerializedData(const_cast<byte*>(data->data()), data->length()) {}
    350 
    351 SerializedCodeData* SerializedCodeData::FromCachedData(Isolate* isolate,
    352                                                        ScriptData* cached_data,
    353                                                        String* source) {
    354   DisallowHeapAllocation no_gc;
    355   SerializedCodeData* scd = new SerializedCodeData(cached_data);
    356   SanityCheckResult r = scd->SanityCheck(isolate, source);
    357   if (r == CHECK_SUCCESS) return scd;
    358   cached_data->Reject();
    359   source->GetIsolate()->counters()->code_cache_reject_reason()->AddSample(r);
    360   delete scd;
    361   return NULL;
    362 }
    363 
    364 }  // namespace internal
    365 }  // namespace v8
    366