src/v8/src/wasm/wasm-module.cc

// Copyright 2015 the V8 project authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#include <functional>
#include <memory>

#include "src/api.h"
#include "src/assembler-inl.h"
#include "src/code-stubs.h"
#include "src/compiler/wasm-compiler.h"
#include "src/debug/interface-types.h"
#include "src/frames-inl.h"
#include "src/objects.h"
#include "src/property-descriptor.h"
#include "src/simulator.h"
#include "src/snapshot/snapshot.h"
#include "src/trap-handler/trap-handler.h"
#include "src/v8.h"
#include "src/wasm/compilation-manager.h"
#include "src/wasm/module-compiler.h"
#include "src/wasm/module-decoder.h"
#include "src/wasm/wasm-code-manager.h"
#include "src/wasm/wasm-code-specialization.h"
#include "src/wasm/wasm-js.h"
#include "src/wasm/wasm-module.h"
#include "src/wasm/wasm-objects-inl.h"
#include "src/wasm/wasm-result.h"

namespace v8 {
namespace internal {
namespace wasm {

// static
const WasmExceptionSig WasmException::empty_sig_(0, 0, nullptr);

// static
constexpr const char* WasmException::kRuntimeIdStr;

// static
constexpr const char* WasmException::kRuntimeValuesStr;

void UnpackAndRegisterProtectedInstructionsGC(Isolate* isolate,
                                              Handle<FixedArray> code_table) {
  DisallowHeapAllocation no_gc;
  std::vector<trap_handler::ProtectedInstructionData> unpacked;

  for (int i = 0; i < code_table->length(); ++i) {
    Object* maybe_code = code_table->get(i);
    // This is sometimes undefined when we're called from cctests.
    if (maybe_code->IsUndefined(isolate)) continue;
    Code* code = Code::cast(maybe_code);

    if (code->kind() != Code::WASM_FUNCTION) {
      continue;
    }

    if (code->trap_handler_index()->value() != trap_handler::kInvalidIndex) {
      // This function has already been registered.
      continue;
    }

    byte* base = code->entry();

    FixedArray* protected_instructions = code->protected_instructions();
    DCHECK(protected_instructions != nullptr);
    for (int i = 0; i < protected_instructions->length();
         i += Code::kTrapDataSize) {
      trap_handler::ProtectedInstructionData data;
      data.instr_offset =
          protected_instructions
              ->GetValueChecked<Smi>(isolate, i + Code::kTrapCodeOffset)
              ->value();
      data.landing_offset =
          protected_instructions
              ->GetValueChecked<Smi>(isolate, i + Code::kTrapLandingOffset)
              ->value();
      unpacked.emplace_back(data);
    }

    if (unpacked.empty()) continue;

    const int index = RegisterHandlerData(base, code->instruction_size(),
                                          unpacked.size(), &unpacked[0]);

    unpacked.clear();

    // TODO(6792): No longer needed once WebAssembly code is off heap.
    CodeSpaceMemoryModificationScope modification_scope(isolate->heap());

    // TODO(eholk): if index is negative, fail.
    DCHECK_LE(0, index);
    code->set_trap_handler_index(Smi::FromInt(index));
  }
}

void UnpackAndRegisterProtectedInstructions(
    Isolate* isolate, const wasm::NativeModule* native_module) {
  DisallowHeapAllocation no_gc;

  for (uint32_t i = native_module->num_imported_functions(),
                e = native_module->FunctionCount();
       i < e; ++i) {
    wasm::WasmCode* code = native_module->GetCode(i);

    if (code == nullptr || code->kind() != wasm::WasmCode::kFunction) {
      continue;
    }

    if (code->HasTrapHandlerIndex()) continue;

    Address base = code->instructions().start();

    size_t size = code->instructions().size();
    const int index =
        RegisterHandlerData(base, size, code->protected_instructions().size(),
                            code->protected_instructions().data());

    // TODO(6792): No longer needed once WebAssembly code is off heap.
    CodeSpaceMemoryModificationScope modification_scope(isolate->heap());

    // TODO(eholk): if index is negative, fail.
    CHECK_LE(0, index);
    code->set_trap_handler_index(static_cast<size_t>(index));
  }
}

std::ostream& operator<<(std::ostream& os, const WasmFunctionName& name) {
  os << "#" << name.function_->func_index;
  if (name.function_->name.is_set()) {
    if (name.name_.start()) {
      os << ":";
      os.write(name.name_.start(), name.name_.length());
    }
  } else {
    os << "?";
  }
  return os;
}

WasmModule::WasmModule(std::unique_ptr<Zone> owned)
    : signature_zone(std::move(owned)) {}

WasmFunction* GetWasmFunctionForExport(Isolate* isolate,
                                       Handle<Object> target) {
  if (target->IsJSFunction()) {
    Handle<JSFunction> func = Handle<JSFunction>::cast(target);
    if (func->code()->kind() == Code::JS_TO_WASM_FUNCTION) {
      auto exported = Handle<WasmExportedFunction>::cast(func);
      Handle<WasmInstanceObject> other_instance(exported->instance(), isolate);
      int func_index = exported->function_index();
      return &other_instance->module()->functions[func_index];
    }
  }
  return nullptr;
}

Handle<Object> GetOrCreateIndirectCallWrapper(
    Isolate* isolate, Handle<WasmInstanceObject> owning_instance,
    WasmCodeWrapper wasm_code, uint32_t index, FunctionSig* sig) {
  Address new_context_address =
      reinterpret_cast<Address>(owning_instance->wasm_context()->get());
  if (!wasm_code.IsCodeObject()) {
    DCHECK_NE(wasm_code.GetWasmCode()->kind(),
              wasm::WasmCode::kWasmToWasmWrapper);
    wasm::NativeModule* native_module = wasm_code.GetWasmCode()->owner();
    // The only reason we pass owning_instance is for the GC case. Check
    // that the values match.
    DCHECK_EQ(owning_instance->compiled_module()->GetNativeModule(),
              native_module);
    // We create the wrapper on the module exporting the function. This
    // wrapper will only be called as indirect call.
    wasm::WasmCode* exported_wrapper =
        native_module->GetExportedWrapper(wasm_code.GetWasmCode()->index());
    if (exported_wrapper == nullptr) {
      Handle<Code> new_wrapper = compiler::CompileWasmToWasmWrapper(
          isolate, wasm_code, sig, new_context_address);
      exported_wrapper = native_module->AddExportedWrapper(
          new_wrapper, wasm_code.GetWasmCode()->index());
    }
    Address target = exported_wrapper->instructions().start();
    return isolate->factory()->NewForeign(target, TENURED);
  }
  Handle<Code> code = compiler::CompileWasmToWasmWrapper(
      isolate, wasm_code, sig, new_context_address);
  AttachWasmFunctionInfo(isolate, code, owning_instance,
                         static_cast<int>(index));
  return code;
}

bool IsWasmCodegenAllowed(Isolate* isolate, Handle<Context> context) {
  // TODO(wasm): Once wasm has its own CSP policy, we should introduce a
  // separate callback that includes information about the module about to be
  // compiled. For the time being, pass an empty string as placeholder for the
  // sources.
  if (auto wasm_codegen_callback = isolate->allow_wasm_code_gen_callback()) {
    return wasm_codegen_callback(
        v8::Utils::ToLocal(context),
        v8::Utils::ToLocal(isolate->factory()->empty_string()));
  }
  auto codegen_callback = isolate->allow_code_gen_callback();
  return codegen_callback == nullptr ||
         codegen_callback(
             v8::Utils::ToLocal(context),
             v8::Utils::ToLocal(isolate->factory()->empty_string()));
}

Handle<JSArray> GetImports(Isolate* isolate,
                           Handle<WasmModuleObject> module_object) {
  Handle<WasmSharedModuleData> shared(
      module_object->compiled_module()->shared(), isolate);
  Factory* factory = isolate->factory();

  Handle<String> module_string = factory->InternalizeUtf8String("module");
  Handle<String> name_string = factory->InternalizeUtf8String("name");
  Handle<String> kind_string = factory->InternalizeUtf8String("kind");

  Handle<String> function_string = factory->InternalizeUtf8String("function");
  Handle<String> table_string = factory->InternalizeUtf8String("table");
  Handle<String> memory_string = factory->InternalizeUtf8String("memory");
  Handle<String> global_string = factory->InternalizeUtf8String("global");

  // Create the result array.
  WasmModule* module = shared->module();
  int num_imports = static_cast<int>(module->import_table.size());
  Handle<JSArray> array_object = factory->NewJSArray(PACKED_ELEMENTS, 0, 0);
  Handle<FixedArray> storage = factory->NewFixedArray(num_imports);
  JSArray::SetContent(array_object, storage);
  array_object->set_length(Smi::FromInt(num_imports));

  Handle<JSFunction> object_function =
      Handle<JSFunction>(isolate->native_context()->object_function(), isolate);

  // Populate the result array.
  for (int index = 0; index < num_imports; ++index) {
    WasmImport& import = module->import_table[index];

    Handle<JSObject> entry = factory->NewJSObject(object_function);

    Handle<String> import_kind;
    switch (import.kind) {
      case kExternalFunction:
        import_kind = function_string;
        break;
      case kExternalTable:
        import_kind = table_string;
        break;
      case kExternalMemory:
        import_kind = memory_string;
        break;
      case kExternalGlobal:
        import_kind = global_string;
        break;
      default:
        UNREACHABLE();
    }

    MaybeHandle<String> import_module =
        WasmSharedModuleData::ExtractUtf8StringFromModuleBytes(
            isolate, shared, import.module_name);

    MaybeHandle<String> import_name =
        WasmSharedModuleData::ExtractUtf8StringFromModuleBytes(
            isolate, shared, import.field_name);

    JSObject::AddProperty(entry, module_string, import_module.ToHandleChecked(),
                          NONE);
    JSObject::AddProperty(entry, name_string, import_name.ToHandleChecked(),
                          NONE);
    JSObject::AddProperty(entry, kind_string, import_kind, NONE);

    storage->set(index, *entry);
  }

  return array_object;
}

Handle<JSArray> GetExports(Isolate* isolate,
                           Handle<WasmModuleObject> module_object) {
  Handle<WasmSharedModuleData> shared(
      module_object->compiled_module()->shared(), isolate);
  Factory* factory = isolate->factory();

  Handle<String> name_string = factory->InternalizeUtf8String("name");
  Handle<String> kind_string = factory->InternalizeUtf8String("kind");

  Handle<String> function_string = factory->InternalizeUtf8String("function");
  Handle<String> table_string = factory->InternalizeUtf8String("table");
  Handle<String> memory_string = factory->InternalizeUtf8String("memory");
  Handle<String> global_string = factory->InternalizeUtf8String("global");

  // Create the result array.
  WasmModule* module = shared->module();
  int num_exports = static_cast<int>(module->export_table.size());
  Handle<JSArray> array_object = factory->NewJSArray(PACKED_ELEMENTS, 0, 0);
  Handle<FixedArray> storage = factory->NewFixedArray(num_exports);
  JSArray::SetContent(array_object, storage);
  array_object->set_length(Smi::FromInt(num_exports));

  Handle<JSFunction> object_function =
      Handle<JSFunction>(isolate->native_context()->object_function(), isolate);

  // Populate the result array.
  for (int index = 0; index < num_exports; ++index) {
    WasmExport& exp = module->export_table[index];

    Handle<String> export_kind;
    switch (exp.kind) {
      case kExternalFunction:
        export_kind = function_string;
        break;
      case kExternalTable:
        export_kind = table_string;
        break;
      case kExternalMemory:
        export_kind = memory_string;
        break;
      case kExternalGlobal:
        export_kind = global_string;
        break;
      default:
        UNREACHABLE();
    }

    Handle<JSObject> entry = factory->NewJSObject(object_function);

    MaybeHandle<String> export_name =
        WasmSharedModuleData::ExtractUtf8StringFromModuleBytes(isolate, shared,
                                                               exp.name);

    JSObject::AddProperty(entry, name_string, export_name.ToHandleChecked(),
                          NONE);
    JSObject::AddProperty(entry, kind_string, export_kind, NONE);

    storage->set(index, *entry);
  }

  return array_object;
}

Handle<JSArray> GetCustomSections(Isolate* isolate,
                                  Handle<WasmModuleObject> module_object,
                                  Handle<String> name, ErrorThrower* thrower) {
  Handle<WasmSharedModuleData> shared(
      module_object->compiled_module()->shared(), isolate);
  Factory* factory = isolate->factory();

  std::vector<CustomSectionOffset> custom_sections;
  {
    DisallowHeapAllocation no_gc;  // for raw access to string bytes.
    Handle<SeqOneByteString> module_bytes(shared->module_bytes(), isolate);
    const byte* start =
        reinterpret_cast<const byte*>(module_bytes->GetCharsAddress());
    const byte* end = start + module_bytes->length();
    custom_sections = DecodeCustomSections(start, end);
  }

  std::vector<Handle<Object>> matching_sections;

  // Gather matching sections.
  for (auto& section : custom_sections) {
    MaybeHandle<String> section_name =
        WasmSharedModuleData::ExtractUtf8StringFromModuleBytes(isolate, shared,
                                                               section.name);

    if (!name->Equals(*section_name.ToHandleChecked())) continue;

    // Make a copy of the payload data in the section.
    size_t size = section.payload.length();
    void* memory =
        size == 0 ? nullptr : isolate->array_buffer_allocator()->Allocate(size);

    if (size && !memory) {
      thrower->RangeError("out of memory allocating custom section data");
      return Handle<JSArray>();
    }
    Handle<JSArrayBuffer> buffer = isolate->factory()->NewJSArrayBuffer();
    constexpr bool is_external = false;
    JSArrayBuffer::Setup(buffer, isolate, is_external, memory, size, memory,
                         size);
    DisallowHeapAllocation no_gc;  // for raw access to string bytes.
    Handle<SeqOneByteString> module_bytes(shared->module_bytes(), isolate);
    const byte* start =
        reinterpret_cast<const byte*>(module_bytes->GetCharsAddress());
    memcpy(memory, start + section.payload.offset(), section.payload.length());

    matching_sections.push_back(buffer);
  }

  int num_custom_sections = static_cast<int>(matching_sections.size());
  Handle<JSArray> array_object = factory->NewJSArray(PACKED_ELEMENTS, 0, 0);
  Handle<FixedArray> storage = factory->NewFixedArray(num_custom_sections);
  JSArray::SetContent(array_object, storage);
  array_object->set_length(Smi::FromInt(num_custom_sections));

  for (int i = 0; i < num_custom_sections; i++) {
    storage->set(i, *matching_sections[i]);
  }

  return array_object;
}

Handle<FixedArray> DecodeLocalNames(Isolate* isolate,
                                    Handle<WasmSharedModuleData> shared) {
  Handle<SeqOneByteString> wire_bytes(shared->module_bytes(), isolate);
  LocalNames decoded_locals;
  {
    DisallowHeapAllocation no_gc;
    DecodeLocalNames(wire_bytes->GetChars(),
                     wire_bytes->GetChars() + wire_bytes->length(),
                     &decoded_locals);
  }
  Handle<FixedArray> locals_names =
      isolate->factory()->NewFixedArray(decoded_locals.max_function_index + 1);
  for (LocalNamesPerFunction& func : decoded_locals.names) {
    Handle<FixedArray> func_locals_names =
        isolate->factory()->NewFixedArray(func.max_local_index + 1);
    locals_names->set(func.function_index, *func_locals_names);
    for (LocalName& name : func.names) {
      Handle<String> name_str =
          WasmSharedModuleData::ExtractUtf8StringFromModuleBytes(
              isolate, shared, name.name)
              .ToHandleChecked();
      func_locals_names->set(name.local_index, *name_str);
    }
  }
  return locals_names;
}
}  // namespace wasm
}  // namespace internal
}  // namespace v8