Source/JavaScriptCore/runtime/JSCConfig.h

/*
 * Copyright (C) 2019-2020 Apple Inc. All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY APPLE INC. ``AS IS'' AND ANY
 * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL APPLE INC. OR
 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
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 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

#pragma once

#include "OptionsList.h"
#include <wtf/WTFConfig.h>

namespace JSC {

class ExecutableAllocator;
class FixedVMPoolExecutableAllocator;
class VM;

constexpr size_t ConfigSizeToProtect = CeilingOnPageSize;

#if ENABLE(SEPARATED_WX_HEAP)
using JITWriteSeparateHeapsFunction = void (*)(off_t, const void*, size_t);
#endif

struct Config {
    JS_EXPORT_PRIVATE static void disableFreezingForTesting();
    JS_EXPORT_PRIVATE static void enableRestrictedOptions();
    static void permanentlyFreeze() { WTF::Config::permanentlyFreeze(); }

    static void configureForTesting()
    {
        disableFreezingForTesting();
        enableRestrictedOptions();
    }

    bool isPermanentlyFrozen() { return g_wtfConfig.isPermanentlyFrozen; }

    // All the fields in this struct should be chosen such that their
    // initial value is 0 / null / falsy because Config is instantiated
    // as a global singleton.

    bool disabledFreezingForTesting;
    bool restrictedOptionsEnabled;
    bool jitDisabled;

    // The following HasBeenCalled flags are for auditing call_once initialization functions.
    bool initializeHasBeenCalled;

    struct {
#if ASSERT_ENABLED
        bool canUseJITIsSet;
#endif
        bool canUseJIT;
    } vm;

    ExecutableAllocator* executableAllocator;
    FixedVMPoolExecutableAllocator* fixedVMPoolExecutableAllocator;
    void* startExecutableMemory;
    void* endExecutableMemory;
    uintptr_t startOfFixedWritableMemoryPool;

#if ENABLE(SEPARATED_WX_HEAP)
    JITWriteSeparateHeapsFunction jitWriteSeparateHeaps;
#endif

    OptionsStorage options;

    void (*shellTimeoutCheckCallback)(VM&);

    WTF::PtrTagLookup ptrTagLookupRecord;
};

constexpr size_t alignmentOfJSCConfig = std::alignment_of<JSC::Config>::value;

static_assert(WTF::offsetOfWTFConfigExtension + sizeof(JSC::Config) <= WTF::ConfigSizeToProtect);
static_assert(roundUpToMultipleOf<alignmentOfJSCConfig>(WTF::offsetOfWTFConfigExtension) == WTF::offsetOfWTFConfigExtension);

#define g_jscConfig (*bitwise_cast<JSC::Config*>(&g_wtfConfig.spaceForExtensions))

} // namespace JSC