runtime/lib/ffi.cc

// Copyright (c) 2019, the Dart project authors.  Please see the AUTHORS file
// for details. All rights reserved. Use of this source code is governed by a
// BSD-style license that can be found in the LICENSE file.

#include "include/dart_api.h"
#include "include/dart_api_dl.h"
#include "include/dart_native_api.h"
#include "include/dart_version.h"
#include "include/internal/dart_api_dl_impl.h"
#include "platform/globals.h"
#include "vm/bootstrap_natives.h"
#include "vm/class_finalizer.h"
#include "vm/class_id.h"
#include "vm/compiler/ffi/native_type.h"
#include "vm/exceptions.h"
#include "vm/flags.h"
#include "vm/heap/gc_shared.h"
#include "vm/log.h"
#include "vm/native_arguments.h"
#include "vm/native_entry.h"
#include "vm/object.h"
#include "vm/object_store.h"
#include "vm/symbols.h"

#if !defined(DART_PRECOMPILED_RUNTIME)
#include "vm/compiler/assembler/assembler.h"
#include "vm/compiler/ffi/call.h"
#include "vm/compiler/ffi/callback.h"
#include "vm/compiler/ffi/marshaller.h"
#include "vm/compiler/jit/compiler.h"
#endif  // !defined(DART_PRECOMPILED_RUNTIME)

namespace dart {

// The remainder of this file implements the dart:ffi native methods.

DEFINE_NATIVE_ENTRY(Ffi_fromAddress, 1, 1) {
  UNREACHABLE();
}

DEFINE_NATIVE_ENTRY(Ffi_address, 0, 1) {
  UNREACHABLE();
}

#define DEFINE_NATIVE_ENTRY_LOAD(type)                                         \
  DEFINE_NATIVE_ENTRY(Ffi_load##type, 0, 2) { UNREACHABLE(); }
CLASS_LIST_FFI_NUMERIC_FIXED_SIZE(DEFINE_NATIVE_ENTRY_LOAD)
#undef DEFINE_NATIVE_ENTRY_LOAD

DEFINE_NATIVE_ENTRY(Ffi_loadPointer, 1, 2) {
  UNREACHABLE();
}

DEFINE_NATIVE_ENTRY(Ffi_loadStruct, 0, 2) {
  UNREACHABLE();
}

#define DEFINE_NATIVE_ENTRY_STORE(type)                                        \
  DEFINE_NATIVE_ENTRY(Ffi_store##type, 0, 3) { UNREACHABLE(); }
CLASS_LIST_FFI_NUMERIC_FIXED_SIZE(DEFINE_NATIVE_ENTRY_STORE)
#undef DEFINE_NATIVE_ENTRY_STORE

DEFINE_NATIVE_ENTRY(Ffi_storePointer, 0, 3) {
  UNREACHABLE();
}

// Static invocations to this method are translated directly in streaming FGB.
DEFINE_NATIVE_ENTRY(Ffi_asFunctionInternal, 2, 2) {
  UNREACHABLE();
}

#define DEFINE_NATIVE_ENTRY_AS_EXTERNAL_TYPED_DATA(type)                       \
  DEFINE_NATIVE_ENTRY(Ffi_asExternalTypedData##type, 0, 2) { UNREACHABLE(); }
CLASS_LIST_FFI_NUMERIC_FIXED_SIZE(DEFINE_NATIVE_ENTRY_AS_EXTERNAL_TYPED_DATA)
#undef DEFINE_NATIVE_ENTRY_AS_EXTERNAL_TYPED_DATA

DEFINE_NATIVE_ENTRY(Ffi_pointerFromFunction, 1, 1) {
  const auto& function = Function::CheckedHandle(zone, arguments->NativeArg0());
  const auto& code =
      Code::Handle(zone, FLAG_precompiled_mode ? function.CurrentCode()
                                               : function.EnsureHasCode());
  ASSERT(!code.IsNull());

#if defined(TARGET_ARCH_IA32)
  // On ia32, store the stack delta that we need to use when returning.
  const intptr_t stack_return_delta =
      function.FfiCSignatureReturnsStruct() && CallingConventions::kUsesRet4
          ? compiler::target::kWordSize
          : 0;
#else
  const intptr_t stack_return_delta = 0;
#endif
  thread->SetFfiCallbackCode(function, code, stack_return_delta);

  uword entry_point = code.EntryPoint();

  // In JIT we use one more indirection:
  //   * AOT: Native -> Ffi Trampoline -> Dart function
  //   * JIT: Native -> Jit trampoline -> Ffi Trampoline -> Dart function
  //
  // We do that since ffi trampoline code lives in Dart heap. During GC we can
  // flip page protections from RX to RW to GC JITed code. During that time
  // machine code on such pages cannot be executed. Native code therefore has to
  // perform the safepoint transition before executing code in Dart heap (which
  // is why we use the jit trampoline).
#if !defined(DART_PRECOMPILED_RUNTIME)
  if (NativeCallbackTrampolines::Enabled()) {
    entry_point = isolate->native_callback_trampolines()->TrampolineForId(
        function.FfiCallbackId());
  }
#endif

  return Pointer::New(entry_point);
}

DEFINE_NATIVE_ENTRY(DartNativeApiFunctionPointer, 0, 1) {
  GET_NON_NULL_NATIVE_ARGUMENT(String, name_dart, arguments->NativeArgAt(0));
  const char* name = name_dart.ToCString();

#define RETURN_FUNCTION_ADDRESS(function_name, R, A)                           \
  if (strcmp(name, #function_name) == 0) {                                     \
    return Integer::New(reinterpret_cast<intptr_t>(function_name));            \
  }
  DART_NATIVE_API_DL_SYMBOLS(RETURN_FUNCTION_ADDRESS)
#undef RETURN_FUNCTION_ADDRESS

  const String& error = String::Handle(
      String::NewFormatted("Unknown dart_native_api.h symbol: %s.", name));
  Exceptions::ThrowArgumentError(error);
}

DEFINE_NATIVE_ENTRY(DartApiDLMajorVersion, 0, 0) {
  return Integer::New(DART_API_DL_MAJOR_VERSION);
}

DEFINE_NATIVE_ENTRY(DartApiDLMinorVersion, 0, 0) {
  return Integer::New(DART_API_DL_MINOR_VERSION);
}

static const DartApiEntry dart_api_entries[] = {
#define ENTRY(name, R, A)                                                      \
  DartApiEntry{#name, reinterpret_cast<void (*)()>(name)},
    DART_API_ALL_DL_SYMBOLS(ENTRY)
#undef ENTRY
        DartApiEntry{nullptr, nullptr}};

static const DartApi dart_api_data = {
    DART_API_DL_MAJOR_VERSION, DART_API_DL_MINOR_VERSION, dart_api_entries};

DEFINE_NATIVE_ENTRY(DartApiDLInitializeData, 0, 0) {
  return Integer::New(reinterpret_cast<intptr_t>(&dart_api_data));
}

DEFINE_FFI_NATIVE_ENTRY(FinalizerEntry_SetExternalSize,
                        void,
                        (Dart_Handle entry_handle, intptr_t external_size)) {
  Thread* const thread = Thread::Current();
  TransitionNativeToVM transition(thread);
  Zone* const zone = thread->zone();
  const auto& entry_object =
      Object::Handle(zone, Api::UnwrapHandle(entry_handle));
  const auto& entry = FinalizerEntry::Cast(entry_object);

  Heap::Space space;
  intptr_t external_size_diff;
  {
    NoSafepointScope no_safepoint;
    space = SpaceForExternal(entry.ptr());
    const intptr_t external_size_old = entry.external_size();
    if (FLAG_trace_finalizers) {
      THR_Print("Setting external size from  %" Pd " to  %" Pd
                " bytes in %s space\n",
                external_size_old, external_size, space == 0 ? "new" : "old");
    }
    external_size_diff = external_size - external_size_old;
    if (external_size_diff == 0) {
      return;
    }
    entry.set_external_size(external_size);
  }
  // The next call cannot be in safepoint.
  if (external_size_diff > 0) {
    if (!thread->isolate_group()->heap()->AllocatedExternal(external_size_diff,
                                                            space)) {
      Exceptions::ThrowOOM();
    }
  } else {
    thread->isolate_group()->heap()->FreedExternal(-external_size_diff, space);
  }
};

}  // namespace dart