PatcherNew.hpp

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/* src/vm/jit/PatcherNew.hpp - Patcher class

   Copyright (C) 1996-2013
   CACAOVM - Verein zur Foerderung der freien virtuellen Maschine CACAO

   This file is part of CACAO.

   This program is free software; you can redistribute it and/or
   modify it under the terms of the GNU General Public License as
   published by the Free Software Foundation; either version 2, or (at
   your option) any later version.

   This program is distributed in the hope that it will be useful, but
   WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
   General Public License for more details.

   You should have received a copy of the GNU General Public License
   along with this program; if not, write to the Free Software
   Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
   02110-1301, USA.

*/

#ifndef _PATCHERNEW_HPP
#define _PATCHERNEW_HPP

#include "vm/jit/patcher-common.hpp"

namespace cacao {

// forward declaration
class OStream;

/**
 * Patcher super class
 *
 * This class is intended to replace the patchref_t patcher references.
 * The goal is to replace function pointers by virtual functions and
 * void pointers by member variables. Although we need a vtbl_ptr for
 * virtual functions and a smart pointer for list storage this might even
 * reduce the overall memory consumption because not all fields of patchref_t
 * are needed by all patchers. But the main focus is on encapsulation and
 * usability.
 *
 * @todo Remove/adopt the text above if the legacy patchref_t framework has
 * been removed.
 */
class Patcher {
private:
    bool done;
    /**
     * This function performs the patching.
     */
    virtual bool patch_impl() = 0;
public:
    Patcher();
    virtual ~Patcher();

    /**
     * This a wrapper to set the done flag.
     */
    bool patch() {
        if (patch_impl()) {
            done = true;
            return true;
        }
        return false;
    }
    /**
     * get the absolute position in code segment
     *
     * @deprecated
     */
    virtual uintptr_t get_mpc() const = 0;
    /**
     * Generates the code for the patcher traps.
     */
    virtual void emit() = 0;
    /**
     * reposition to another base
     */
    virtual void reposition(intptr_t base) = 0;
    /**
     * Check already patched
     *
     * In contrast to check_is_patched this method simply
     * queries a boolean variable whereas check_is_patched
     * inspects to machine code.
     *
     * @see check_is_patched
     */
    bool is_patched() const {
        return done;
    }
    /**
     * Check if the patcher is already patched.
     *
     * This is done by comparing the machine instruction.
     *
     * @return true if patched, false otherwise.
     * @see is_patched
     */
    virtual bool check_is_patched() const = 0;
    /**
     * print patcher information
     */
    virtual const char* get_name() const;
    /**
     * print patcher information
     */
    virtual OStream& print(OStream &OS) const;
};

class LegacyPatcher : public Patcher {
private:
    jitdata *jd;
    patchref_t pr;

    /**
     * Call the legacy patching function
     */
    virtual bool patch_impl() {
        // define the patcher function
        bool (*patcher_function)(patchref_t *);
        // cast the passed function to a patcher function
        patcher_function = (bool (*)(patchref_t *)) (ptrint) pr.patcher;

        return (patcher_function)(&pr);
    }

public:

    LegacyPatcher(jitdata *jd, const patchref_t &pr)
        : Patcher(), jd(jd), pr(pr) {}

    /**
     * return the raw resource
     */
    patchref_t* get() {
        return ≺
    }

    virtual uintptr_t get_mpc() const {
        return pr.mpc;
    }
    virtual void emit();
    virtual void reposition(intptr_t base) {
        pr.mpc   += base;
        pr.datap  = (intptr_t) (pr.disp + base);
    }
    /**
     * Check if the patcher is already patched.
     *
     * This is done by comparing the machine instruction.
     *
     * @return true if patched, false otherwise.
     */
    virtual bool check_is_patched() const;

    virtual const char* get_name() const;
    virtual OStream& print(OStream &OS) const;
};

/**
 * Base class for all (non-legacy) patcher
 */
class PatcherBase : public Patcher {
private:
    uint32_t  mcode;
    uintptr_t mpc;
public:
    PatcherBase() : Patcher(), mcode(0), mpc(0) {}
    explicit PatcherBase(uintptr_t mpc) : Patcher(), mcode(0), mpc(mpc) {}

    virtual void set_mcode(uint32_t mcode) {
        this->mcode = mcode;
    }
    #if 0
    virtual uintptr_t get_mcode() const {
        return mcode;
    }
    #endif
    virtual uintptr_t get_mpc() const {
        return mpc;
    }
    virtual void reposition(intptr_t base) {
        this->mpc   += base;
    }
    virtual const char* get_name() const {
        return "PatcherBase";
    }
};

class InitializeClassPatcher : public PatcherBase {
private:
    classinfo *c;

    virtual bool patch_impl();
public:
    virtual void emit();
    virtual bool check_is_patched() const;
    InitializeClassPatcher(classinfo *c) : c(c) {}
    virtual const char* get_name() const {
        return "InitializeClassPatcher";
    }
};

} // end namespace cacao

#endif // _PATCHERNEW_HPP


/*
 * These are local overrides for various environment variables in Emacs.
 * Please do not remove this and leave it at the end of the file, where
 * Emacs will automagically detect them.
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