Source/JavaScriptCore/wasm/js/JSWebAssemblyCodeBlock.cpp

/*
 * Copyright (C) 2017 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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#include "config.h"
#include "JSWebAssemblyCodeBlock.h"

#if ENABLE(WEBASSEMBLY)

#include "JSCInlines.h"
#include "JSWebAssemblyLinkError.h"
#include "JSWebAssemblyMemory.h"
#include "JSWebAssemblyModule.h"
#include "WasmPlanInlines.h"

namespace JSC {

const ClassInfo JSWebAssemblyCodeBlock::s_info = { "WebAssemblyCodeBlock", nullptr, 0, CREATE_METHOD_TABLE(JSWebAssemblyCodeBlock) };

JSWebAssemblyCodeBlock::JSWebAssemblyCodeBlock(VM& vm, JSWebAssemblyModule* owner,  Wasm::MemoryMode mode, Ref<Wasm::Plan>&& plan, unsigned calleeCount)
    : Base(vm, vm.webAssemblyCodeBlockStructure.get())
    , m_plan(WTFMove(plan))
    , m_mode(mode)
    , m_calleeCount(calleeCount)
{
    m_module.set(vm, this, owner);
    ASSERT(!module()->codeBlock(mode));
    module()->setCodeBlock(vm, mode, this);

    memset(callees(), 0, m_calleeCount * sizeof(WriteBarrier<JSWebAssemblyCallee>) * 2);
}

void JSWebAssemblyCodeBlock::initialize()
{
    if (initialized())
        return;

    VM& vm = plan().vm();
    ASSERT(vm.currentThreadIsHoldingAPILock());
    RELEASE_ASSERT(!plan().hasWork());

    if (plan().failed()) {
        m_errorMessage = plan().errorMessage();
        m_plan = nullptr;
        return;
    }

    RELEASE_ASSERT(plan().mode() == mode());
    ASSERT(plan().internalFunctionCount() == m_calleeCount);

    m_callLinkInfos = plan().takeCallLinkInfos();
    m_wasmExitStubs = plan().takeWasmExitStubs();

    plan().initializeCallees([&] (unsigned calleeIndex, JSWebAssemblyCallee* jsEntrypointCallee, JSWebAssemblyCallee* wasmEntrypointCallee) {
        setJSEntrypointCallee(vm, calleeIndex, jsEntrypointCallee);
        setWasmEntrypointCallee(vm, calleeIndex, wasmEntrypointCallee);
    });

    m_plan = nullptr;
}

void JSWebAssemblyCodeBlock::destroy(JSCell* cell)
{
    static_cast<JSWebAssemblyCodeBlock*>(cell)->JSWebAssemblyCodeBlock::~JSWebAssemblyCodeBlock();
}

bool JSWebAssemblyCodeBlock::isSafeToRun(JSWebAssemblyMemory* memory) const
{
    if (!runnable())
        return false;

    Wasm::MemoryMode codeMode = mode();
    Wasm::MemoryMode memoryMode = memory->memory().mode();
    switch (codeMode) {
    case Wasm::MemoryMode::BoundsChecking:
        return true;
    case Wasm::MemoryMode::Signaling:
        // Code being in Signaling mode means that it performs no bounds checks.
        // Its memory, even if empty, absolutely must also be in Signaling mode
        // because the page protection detects out-of-bounds accesses.
        return memoryMode == Wasm::MemoryMode::Signaling;
    case Wasm::MemoryMode::NumberOfMemoryModes:
        break;
    }
    RELEASE_ASSERT_NOT_REACHED();
    return false;
}

void JSWebAssemblyCodeBlock::visitChildren(JSCell* cell, SlotVisitor& visitor)
{
    JSWebAssemblyCodeBlock* thisObject = jsCast<JSWebAssemblyCodeBlock*>(cell);
    ASSERT_GC_OBJECT_INHERITS(thisObject, info());

    Base::visitChildren(thisObject, visitor);
    visitor.append(thisObject->m_module);
    for (unsigned i = 0; i < thisObject->m_calleeCount * 2; i++)
        visitor.append(thisObject->callees()[i]);

    visitor.addUnconditionalFinalizer(&thisObject->m_unconditionalFinalizer);
}

void JSWebAssemblyCodeBlock::UnconditionalFinalizer::finalizeUnconditionally()
{
    JSWebAssemblyCodeBlock* thisObject = bitwise_cast<JSWebAssemblyCodeBlock*>(
        bitwise_cast<char*>(this) - OBJECT_OFFSETOF(JSWebAssemblyCodeBlock, m_unconditionalFinalizer));
    for (auto iter = thisObject->m_callLinkInfos.begin(); !!iter; ++iter)
        (*iter)->visitWeak(*thisObject->vm());
}

} // namespace JSC

#endif // ENABLE(WEBASSEMBLY)