Source/JavaScriptCore/assembler/CPU.cpp

/*
 * Copyright (C) 2019 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
 * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
 * OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 
 */

#include "config.h"
#include "CPU.h"

#if (CPU(X86) || CPU(X86_64)) && OS(DARWIN)
#include <mutex>
#include <sys/sysctl.h>
#endif

namespace JSC {

#if (CPU(X86) || CPU(X86_64)) && OS(DARWIN)
bool isKernTCSMAvailable()
{
    uint32_t val = 0;
    size_t valSize = sizeof(val);
    int rc = sysctlbyname("kern.tcsm_available", &val, &valSize, NULL, 0);
    if (rc < 0)
        return false;
    return !!val;
}

bool enableKernTCSM()
{
    uint32_t val = 1;
    int rc = sysctlbyname("kern.tcsm_enable", NULL, 0, &val, sizeof(val));
    if (rc < 0)
        return false;
    return true;
}

int kernTCSMAwareNumberOfProcessorCores()
{
    static std::once_flag onceFlag;
    static int result;
    std::call_once(onceFlag, [] {
        result = WTF::numberOfProcessorCores();
        if (result <= 1)
            return;
        if (isKernTCSMAvailable())
            --result;
    });
    return result;
}
#endif // #if (CPU(X86) || CPU(X86_64)) && OS(DARWIN)

} // namespace JSC