qv4functiontable_unix.cpp

++ // Copyright (C) 2017 The Qt Company Ltd.

++ // SPDX-License-Identifier: LicenseRef-Qt-Commercial OR LGPL-3.0-only OR GPL-2.0-only OR GPL-3.0-only

++ // Qt-Security score:significant

++

++ #include "qv4functiontable_p.h"

++ #include "qv4function_p.h"

++

++ #include <assembler/MacroAssemblerCodeRef.h>

++

++ #include <QtCore/qfile.h>

++ #include <QtCore/qcoreapplication.h>

++

++ QT_BEGIN_NAMESPACE

++

++ namespace QV4 {

++

++ void generateFunctionTable(Function *function, JSC::MacroAssemblerCodeRef *codeRef)

++ {

++     // This implements writing of JIT'd addresses so that perf can find the

++     // symbol names.

++     //

++     // Perf expects the mapping to be in a certain place and have certain

++     // content, for more information, see:

++     // https://github.com/torvalds/linux/blob/master/tools/perf/Documentation/jit-interface.txt

++     static bool doProfile = !qEnvironmentVariableIsEmpty("QV4_PROFILE_WRITE_PERF_MAP");

++     if (Q_UNLIKELY(doProfile)) {

++         static QFile perfMapFile(QString::fromLatin1("/tmp/perf-%1.map")

++                                  .arg(QCoreApplication::applicationPid()));

++         static const bool isOpen = perfMapFile.open(QIODevice::WriteOnly);

++         if (!isOpen) {

++             qWarning("QV4::JIT::Assembler: Cannot write perf map file.");

++             doProfile = false;

++         } else {

++             const void *address = codeRef->code().executableAddress();

++             perfMapFile.write(QByteArray::number(reinterpret_cast<quintptr>(address), 16));

++             perfMapFile.putChar(' ');

++             perfMapFile.write(QByteArray::number(static_cast<qsizetype>(codeRef->size()), 16));

++             perfMapFile.putChar(' ');

++             perfMapFile.write(Function::prettyName(function, address).toUtf8());

++             perfMapFile.putChar('\n');

++             perfMapFile.flush();

++         }

++     }

++ }

++

++ void destroyFunctionTable(Function *function, JSC::MacroAssemblerCodeRef *codeRef)

++ {

++     Q_UNUSED(function);

++     Q_UNUSED(codeRef);

++

++     // It's not advisable to remove things from the perf map file, as it's primarily used to analyze

++     // a trace after the application has terminated. We want to know about all functions that were

++     // ever jitted then. If the memory ranges overlap, we will have a problem when analyzing the

++     // trace. The JIT should try to avoid this.

++ }

++

++ size_t exceptionHandlerSize()

++ {

++     return 0;

++ }

++

++ } // QV4

++

++ QT_END_NAMESPACE

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