Make all VTables const

Summary: There are a few good reasons to make VTables, which are already logically const, physically const: * Compiler enforces constness * Security: often put in a read-only section of memory that can't be tampered with * Performance: compiler knows the contents of the table won't change (I don't expect a lot from this anywhere important) In particular, this prevents a wild write from somewhere in the program from modifying any part of a VTable. We'll know if an invalid CellKind is in a VTable, it is a bad VTable pointer, not some modification of the VTable. Reviewed By: tmikov Differential Revision: D24553780 fbshipit-source-id: 45cd5ce64666a80ef53aabc1f73fc03f299e8bed
gfx · Oct 28, 2020 · e1d4b67 · e1d4b67
1 parent 03e3304
commit e1d4b67
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Showing 36 changed files with 75 additions and 74 deletions.
diff --git a/include/hermes/VM/ArrayStorage.h b/include/hermes/VM/ArrayStorage.h
@@ -36,7 +36,7 @@ class ArrayStorage final
   using size_type = uint32_t;
   using iterator = GCHermesValue *;
 
-  static VTable vt;
+  static const VTable vt;
 
 #ifdef HERMESVM_SERIALIZE
   /// A convinience method to serialize an ArrayStorage which does not contain

diff --git a/include/hermes/VM/Callable.h b/include/hermes/VM/Callable.h
@@ -39,7 +39,7 @@ class Environment final
   friend void EnvironmentDeserialize(Deserializer &d, CellKind kind);
 #endif
 
-  static VTable vt;
+  static const VTable vt;
 
   static bool classof(const GCCell *cell) {
     return cell->getKind() == CellKind::EnvironmentKind;
@@ -367,7 +367,7 @@ class BoundFunction final : public Callable {
 
  public:
   using Super = Callable;
-  static CallableVTable vt;
+  static const CallableVTable vt;
 
   static bool classof(const GCCell *cell) {
     return cell->getKind() == CellKind::BoundFunctionKind;
@@ -484,7 +484,7 @@ class NativeFunction : public Callable {
 #endif
 
   using Super = Callable;
-  static CallableVTable vt;
+  static const CallableVTable vt;
 
   static bool classof(const GCCell *cell) {
     return kindInRange(
@@ -976,7 +976,7 @@ class JSFunction : public Callable {
             codeBlock) {}
 
  public:
-  static CallableVTable vt;
+  static const CallableVTable vt;
 
   static bool classof(const GCCell *cell) {
     return kindInRange(
@@ -1051,7 +1051,7 @@ class JSGeneratorFunction final : public JSFunction {
   static constexpr auto kHasFinalizer = HasFinalizer::No;
 
  public:
-  static CallableVTable vt;
+  static const CallableVTable vt;
 
   /// Create a GeneratorFunction.
   static PseudoHandle<JSGeneratorFunction> create(
@@ -1145,7 +1145,7 @@ class GeneratorInnerFunction final : public JSFunction {
   static constexpr auto kHasFinalizer = HasFinalizer::No;
 
  public:
-  static CallableVTable vt;
+  static const CallableVTable vt;
 
   static bool classof(const GCCell *cell) {
     return cell->getKind() == CellKind::GeneratorInnerFunctionKind;

diff --git a/include/hermes/VM/DecoratedObject.h b/include/hermes/VM/DecoratedObject.h
@@ -91,7 +91,7 @@ class DecoratedObject : public JSObject {
   }
 
   using Super = JSObject;
-  static ObjectVTable vt;
+  static const ObjectVTable vt;
   static bool classof(const GCCell *cell) {
     return kindInRange(
         cell->getKind(),

diff --git a/include/hermes/VM/DictPropertyMap.h b/include/hermes/VM/DictPropertyMap.h
@@ -179,7 +179,7 @@ class DictPropertyMap final : public VariableSizeRuntimeCell,
     friend class OptValue<PropertyPos>;
   };
 
-  static VTable vt;
+  static const VTable vt;
 
   static bool classof(const GCCell *cell) {
     return cell->getKind() == CellKind::DictPropertyMapKind;

diff --git a/include/hermes/VM/Domain.h b/include/hermes/VM/Domain.h
@@ -44,7 +44,7 @@ class Domain final : public GCCell {
   using Super = GCCell;
   friend void DomainBuildMeta(const GCCell *cell, Metadata::Builder &mb);
 
-  static VTable vt;
+  static const VTable vt;
 
   /// Offsets for fields in the cjsModules_ ArrayStorage which contain
   /// information about each individual module.
@@ -245,7 +245,7 @@ class RequireContext final : public JSObject {
   friend GC;
   using Super = JSObject;
 
-  static ObjectVTable vt;
+  static const ObjectVTable vt;
   friend void RequireContextBuildMeta(
       const GCCell *cell,
       Metadata::Builder &mb);

diff --git a/include/hermes/VM/HiddenClass.h b/include/hermes/VM/HiddenClass.h
@@ -280,7 +280,7 @@ class HiddenClass final : public GCCell {
   /// mode".
   static constexpr unsigned kDictionaryThreshold = 64;
 
-  static VTable vt;
+  static const VTable vt;
 
   static bool classof(const GCCell *cell) {
     return cell->getKind() == CellKind::HiddenClassKind;

diff --git a/include/hermes/VM/HostModel.h b/include/hermes/VM/HostModel.h
@@ -26,7 +26,7 @@ class FinalizableNativeFunction final : public NativeFunction {
   FinalizeNativeFunctionPtr finalizePtr_;
 
  public:
-  static CallableVTable vt;
+  static const CallableVTable vt;
 
   static bool classof(const GCCell *cell) {
     return cell->getKind() == CellKind::FinalizableNativeFunctionKind;
@@ -100,7 +100,7 @@ class HostObject final : public DecoratedObject {
   friend GC;
 
  public:
-  static ObjectVTable vt;
+  static const ObjectVTable vt;
 
   static bool classof(const GCCell *cell) {
     return cell->getKind() == CellKind::HostObjectKind;

diff --git a/include/hermes/VM/JSArray.h b/include/hermes/VM/JSArray.h
@@ -246,7 +246,7 @@ class Arguments final : public ArrayImpl {
   using Super = ArrayImpl;
 
  public:
-  static ObjectVTable vt;
+  static const ObjectVTable vt;
 
   // We need one more slot for the '.length' property.
   static const PropStorage::size_type NAMED_PROPERTY_SLOTS =
@@ -290,7 +290,7 @@ class JSArray final : public ArrayImpl {
   friend void ArraySerialize(Serializer &s, const GCCell *cell);
 #endif
 
-  static ObjectVTable vt;
+  static const ObjectVTable vt;
 
   // We need one more slot for the '.length' property.
   static const PropStorage::size_type NAMED_PROPERTY_SLOTS =
@@ -433,7 +433,7 @@ class JSArrayIterator : public JSObject {
   friend void ArrayIteratorBuildMeta(const GCCell *cell, Metadata::Builder &mb);
 
  public:
-  static ObjectVTable vt;
+  static const ObjectVTable vt;
 
   static bool classof(const GCCell *cell) {
     return cell->getKind() == CellKind::ArrayIteratorKind;

diff --git a/include/hermes/VM/JSArrayBuffer.h b/include/hermes/VM/JSArrayBuffer.h
@@ -26,7 +26,7 @@ class JSArrayBuffer final : public JSObject {
   // amount is larger than the native platform's `size_t`
   using size_type = std::size_t;
 
-  static ObjectVTable vt;
+  static const ObjectVTable vt;
 
   static bool classof(const GCCell *cell) {
     return cell->getKind() == CellKind::ArrayBufferKind;

diff --git a/include/hermes/VM/JSDataView.h b/include/hermes/VM/JSDataView.h
@@ -24,7 +24,7 @@ class JSDataView final : public JSObject {
   using size_type = JSArrayBuffer::size_type;
   using Super = JSObject;
 
-  static ObjectVTable vt;
+  static const ObjectVTable vt;
 
   static bool classof(const GCCell *cell) {
     return cell->getKind() == CellKind::DataViewKind;

diff --git a/include/hermes/VM/JSDate.h b/include/hermes/VM/JSDate.h
@@ -18,7 +18,7 @@ class JSDate final : public JSObject {
   using Super = JSObject;
 
  public:
-  static ObjectVTable vt;
+  static const ObjectVTable vt;
 
   /// Need one anonymous slot for the [[PrimitiveValue]] internal property.
   static const PropStorage::size_type ANONYMOUS_PROPERTY_SLOTS =

diff --git a/include/hermes/VM/JSError.h b/include/hermes/VM/JSError.h
@@ -49,7 +49,7 @@ class JSError final : public JSObject {
 #endif
 
   using Super = JSObject;
-  static ObjectVTable vt;
+  static const ObjectVTable vt;
   static bool classof(const GCCell *cell) {
     return cell->getKind() == CellKind::ErrorKind;
   }

diff --git a/include/hermes/VM/JSObject.h b/include/hermes/VM/JSObject.h
@@ -359,7 +359,7 @@ class JSObject : public GCCell {
   serializeObjectImpl(Serializer &s, const GCCell *cell, unsigned overlapSlots);
 #endif
 
-  static ObjectVTable vt;
+  static const ObjectVTable vt;
 
   /// Default capacity of indirect property storage.
   static const PropStorage::size_type DEFAULT_PROPERTY_CAPACITY = 4;
@@ -1476,7 +1476,7 @@ class PropertyAccessor final : public GCCell {
   PropertyAccessor(Deserializer &d);
 #endif
 
-  static VTable vt;
+  static const VTable vt;
 
   static bool classof(const GCCell *cell) {
     return cell->getKind() == CellKind::PropertyAccessorKind;

diff --git a/include/hermes/VM/JSRegExp.h b/include/hermes/VM/JSRegExp.h
@@ -24,7 +24,7 @@ class JSRegExp final : public JSObject {
 
  public:
   using Super = JSObject;
-  static ObjectVTable vt;
+  static const ObjectVTable vt;
   static bool classof(const GCCell *cell) {
     return cell->getKind() == CellKind::RegExpKind;
   }

diff --git a/include/hermes/VM/JSRegExpStringIterator.h b/include/hermes/VM/JSRegExpStringIterator.h
@@ -24,7 +24,7 @@ class JSRegExpStringIterator : public JSObject {
       Metadata::Builder &mb);
 
  public:
-  static ObjectVTable vt;
+  static const ObjectVTable vt;
 
   static bool classof(const GCCell *cell) {
     return cell->getKind() == CellKind::RegExpStringIteratorKind;

diff --git a/include/hermes/VM/OrderedHashMap.h b/include/hermes/VM/OrderedHashMap.h
@@ -25,7 +25,7 @@ class HashMapEntry final : public GCCell {
   friend GC;
 
  public:
-  static VTable vt;
+  static const VTable vt;
 
   /// The key.
   GCHermesValue key;
@@ -92,7 +92,7 @@ class OrderedHashMap final : public GCCell {
       Metadata::Builder &mb);
 
  public:
-  static VTable vt;
+  static const VTable vt;
 
 #ifdef HERMESVM_SERIALIZE
   OrderedHashMap(Deserializer &d);

diff --git a/include/hermes/VM/PrimitiveBox.h b/include/hermes/VM/PrimitiveBox.h
@@ -75,7 +75,7 @@ class JSString final : public PrimitiveBox {
   // We need one more slot for the length property.
   static const PropStorage::size_type NAMED_PROPERTY_SLOTS =
       Super::NAMED_PROPERTY_SLOTS + 1;
-  static ObjectVTable vt;
+  static const ObjectVTable vt;
 
   static bool classof(const GCCell *cell) {
     return cell->getKind() == CellKind::StringObjectKind;
@@ -172,7 +172,7 @@ class JSStringIterator : public JSObject {
       Metadata::Builder &mb);
 
  public:
-  static ObjectVTable vt;
+  static const ObjectVTable vt;
 
   static bool classof(const GCCell *cell) {
     return cell->getKind() == CellKind::StringIteratorKind;
@@ -217,7 +217,7 @@ class JSNumber final : public PrimitiveBox {
   friend GC;
 
  public:
-  static ObjectVTable vt;
+  static const ObjectVTable vt;
 
 #ifdef HERMESVM_SERIALIZE
   JSNumber(Deserializer &d, const VTable *vt);
@@ -246,7 +246,7 @@ class JSBoolean final : public PrimitiveBox {
   friend GC;
 
  public:
-  static ObjectVTable vt;
+  static const ObjectVTable vt;
 
 #ifdef HERMESVM_SERIALIZE
   JSBoolean(Deserializer &d, const VTable *vt);
@@ -278,7 +278,7 @@ class JSSymbol final : public PrimitiveBox {
   friend GC;
 
  public:
-  static ObjectVTable vt;
+  static const ObjectVTable vt;
 
   static bool classof(const GCCell *cell) {
     return cell->getKind() == CellKind::SymbolObjectKind;

diff --git a/include/hermes/VM/SegmentedArray.h b/include/hermes/VM/SegmentedArray.h
@@ -106,7 +106,7 @@ class SegmentedArray final
 #endif
 
     friend void SegmentBuildMeta(const GCCell *cell, Metadata::Builder &mb);
-    static VTable vt;
+    static const VTable vt;
 
     AtomicIfConcurrentGC<uint32_t> length_;
     GCHermesValue data_[kMaxLength];
@@ -357,7 +357,7 @@ class SegmentedArray final
   }
 
  private:
-  static VTable vt;
+  static const VTable vt;
 
   friend TrailingObjects;
   friend void SegmentBuildMeta(const GCCell *cell, Metadata::Builder &mb);

diff --git a/lib/VM/ArrayStorage.cpp b/lib/VM/ArrayStorage.cpp
@@ -15,7 +15,7 @@
 namespace hermes {
 namespace vm {
 
-VTable ArrayStorage::vt(
+const VTable ArrayStorage::vt(
     CellKind::ArrayStorageKind,
     0,
     nullptr,

diff --git a/lib/VM/Callable.cpp b/lib/VM/Callable.cpp
@@ -27,7 +27,7 @@ namespace vm {
 //===----------------------------------------------------------------------===//
 // class Environment
 
-VTable Environment::vt{CellKind::EnvironmentKind, 0};
+const VTable Environment::vt{CellKind::EnvironmentKind, 0};
 
 void EnvironmentBuildMeta(const GCCell *cell, Metadata::Builder &mb) {
   const auto *self = static_cast<const Environment *>(cell);
@@ -483,7 +483,7 @@ CallResult<double> Callable::extractOwnLengthProperty_RJS(
 //===----------------------------------------------------------------------===//
 // class BoundFunction
 
-CallableVTable BoundFunction::vt{
+const CallableVTable BoundFunction::vt{
     {
         VTable(
             CellKind::BoundFunctionKind,
@@ -887,7 +887,7 @@ CallResult<PseudoHandle<>> BoundFunction::_callImpl(
 //===----------------------------------------------------------------------===//
 // class NativeFunction
 
-CallableVTable NativeFunction::vt{
+const CallableVTable NativeFunction::vt{
     {
         VTable(
             CellKind::NativeFunctionKind,
@@ -1183,7 +1183,7 @@ CallResult<PseudoHandle<>> NativeConstructor::_callImpl(
 //===----------------------------------------------------------------------===//
 // class JSFunction
 
-CallableVTable JSFunction::vt{
+const CallableVTable JSFunction::vt{
     {
         VTable(
             CellKind::FunctionKind,
@@ -1315,7 +1315,7 @@ void JSFunction::_snapshotAddLocationsImpl(
 //===----------------------------------------------------------------------===//
 // class JSGeneratorFunction
 
-CallableVTable JSGeneratorFunction::vt{
+const CallableVTable JSGeneratorFunction::vt{
     {
         VTable(
             CellKind::GeneratorFunctionKind,
@@ -1391,7 +1391,7 @@ PseudoHandle<JSGeneratorFunction> JSGeneratorFunction::create(
 //===----------------------------------------------------------------------===//
 // class GeneratorInnerFunction
 
-CallableVTable GeneratorInnerFunction::vt{
+const CallableVTable GeneratorInnerFunction::vt{
     {
         VTable(
             CellKind::GeneratorInnerFunctionKind,

diff --git a/lib/VM/DecoratedObject.cpp b/lib/VM/DecoratedObject.cpp
@@ -18,7 +18,7 @@ size_t DecoratedObject::Decoration::getMallocSize() const {
   return sizeof *this;
 }
 
-ObjectVTable DecoratedObject::vt{
+const ObjectVTable DecoratedObject::vt{
     VTable(
         CellKind::DecoratedObjectKind,
         cellSize<DecoratedObject>(),

diff --git a/lib/VM/DictPropertyMap.cpp b/lib/VM/DictPropertyMap.cpp
@@ -49,7 +49,7 @@ struct DictPropertyMap::detail {
       "too few bits to store max possible descriptor index");
 };
 
-VTable DictPropertyMap::vt{CellKind::DictPropertyMapKind, 0};
+const VTable DictPropertyMap::vt{CellKind::DictPropertyMapKind, 0};
 
 void DictPropertyMapBuildMeta(const GCCell *cell, Metadata::Builder &mb) {
   const auto *self = static_cast<const DictPropertyMap *>(cell);