src/mem/port_proxy.hh

/*
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 * this software without specific prior written permission.
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 * Authors: Andreas Hansson
 */

/**
 * @file
 * PortProxy Object Declaration.
 *
 * Port proxies are used when non-structural entities need access to
 * the memory system (or structural entities that want to peak into
 * the memory system without making a real memory access).
 *
 * Proxy objects replace the previous FunctionalPort, TranslatingPort
 * and VirtualPort objects, which provided the same functionality as
 * the proxies, but were instances of ports not corresponding to real
 * structural ports of the simulated system. Via the port proxies all
 * the accesses go through an actual port (either the system port,
 * e.g. for processes or initialisation, or a the data port of the
 * CPU, e.g. for threads) and thus are transparent to a potentially
 * distributed memory and automatically adhere to the memory map of
 * the system.
 */

#ifndef __MEM_PORT_PROXY_HH__
#define __MEM_PORT_PROXY_HH__

#include <functional>
#include <limits>

#include "mem/port.hh"
#include "sim/byteswap.hh"

/**
 * This object is a proxy for a port or other object which implements the
 * functional response protocol, to be used for debug accesses.
 *
 * This proxy object is used when non structural entities
 * (e.g. thread contexts, object file loaders) need access to the
 * memory system. It calls the corresponding functions on the underlying
 * protocol, and provides templatized convenience access functions.
 *
 * The addresses are interpreted as physical addresses.
 *
 * @sa SETranslatingProxy
 * @sa FSTranslatingProxy
 */
class PortProxy : FunctionalRequestProtocol
{
  public:
    typedef std::function<void(PacketPtr pkt)> SendFunctionalFunc;

  private:
    SendFunctionalFunc sendFunctional;

    /** Granularity of any transactions issued through this proxy. */
    const unsigned int _cacheLineSize;

    void
    recvFunctionalSnoop(PacketPtr pkt) override
    {
        // Since port proxies aren't anyone else's peer, they should never
        // receive snoops.
        panic("Port proxies should never receive snoops.");
    }

  public:
    PortProxy(SendFunctionalFunc func, unsigned int cacheLineSize) :
        sendFunctional(func), _cacheLineSize(cacheLineSize)
    {}
    PortProxy(const MasterPort &port, unsigned int cacheLineSize) :
        sendFunctional([&port](PacketPtr pkt)->void {
                port.sendFunctional(pkt);
            }), _cacheLineSize(cacheLineSize)
    {}
    virtual ~PortProxy() { }



    /** Fixed functionality for use in base classes. */

    /**
     * Read size bytes memory at physical address and store in p.
     */
    void readBlobPhys(Addr addr, Request::Flags flags,
                      void *p, int size) const;

    /**
     * Write size bytes from p to physical address.
     */
    void writeBlobPhys(Addr addr, Request::Flags flags,
                       const void *p, int size) const;

    /**
     * Fill size bytes starting at physical addr with byte value val.
     */
    void memsetBlobPhys(Addr addr, Request::Flags flags,
                        uint8_t v, int size) const;



    /** Methods to override in base classes */

    /**
     * Read size bytes memory at address and store in p.
     * Returns true on success and false on failure.
     */
    virtual bool
    tryReadBlob(Addr addr, void *p, int size) const
    {
        readBlobPhys(addr, 0, p, size);
        return true;
    }

    /**
     * Write size bytes from p to address.
     * Returns true on success and false on failure.
     */
    virtual bool
    tryWriteBlob(Addr addr, const void *p, int size) const
    {
        writeBlobPhys(addr, 0, p, size);
        return true;
    }

    /**
     * Fill size bytes starting at addr with byte value val.
     * Returns true on success and false on failure.
     */
    virtual bool
    tryMemsetBlob(Addr addr, uint8_t val, int size) const
    {
        memsetBlobPhys(addr, 0, val, size);
        return true;
    }



    /** Higher level interfaces based on the above. */

    /**
     * Same as tryReadBlob, but insists on success.
     */
    void
    readBlob(Addr addr, void *p, int size) const
    {
        if (!tryReadBlob(addr, p, size))
            fatal("readBlob(%#x, ...) failed", addr);
    }

    /**
     * Same as tryWriteBlob, but insists on success.
     */
    void
    writeBlob(Addr addr, const void *p, int size) const
    {
        if (!tryWriteBlob(addr, p, size))
            fatal("writeBlob(%#x, ...) failed", addr);
    }

    /**
     * Same as tryMemsetBlob, but insists on success.
     */
    void
    memsetBlob(Addr addr, uint8_t v, int size) const
    {
        if (!tryMemsetBlob(addr, v, size))
            fatal("memsetBlob(%#x, ...) failed", addr);
    }

    /**
     * Read sizeof(T) bytes from address and return as object T.
     */
    template <typename T>
    T read(Addr address) const;

    /**
     * Write object T to address. Writes sizeof(T) bytes.
     */
    template <typename T>
    void write(Addr address, const T &data) const;

    /**
     * Read sizeof(T) bytes from address and return as object T.
     * Performs endianness conversion from the selected guest to host order.
     */
    template <typename T>
    T read(Addr address, ByteOrder guest_byte_order) const;

    /**
     * Write object T to address. Writes sizeof(T) bytes.
     * Performs endianness conversion from host to the selected guest order.
     */
    template <typename T>
    void write(Addr address, T data, ByteOrder guest_byte_order) const;

    /**
     * Write the string str into guest memory at address addr.
     * Returns true on success and false on failure.
     */
    bool tryWriteString(Addr addr, const char *str) const;

    /**
     * Same as tryWriteString, but insists on success.
     */
    void
    writeString(Addr addr, const char *str) const
    {
        if (!tryWriteString(addr, str))
            fatal("writeString(%#x, ...) failed", addr);
    }

    /**
     * Reads the string at guest address addr into the std::string str.
     * Returns true on success and false on failure.
     */
    bool tryReadString(std::string &str, Addr addr) const;

    /**
     * Same as tryReadString, but insists on success.
     */
    void
    readString(std::string &str, Addr addr) const
    {
        if (!tryReadString(str, addr))
            fatal("readString(%#x, ...) failed", addr);
    }

    /**
     * Reads the string at guest address addr into the char * str, reading up
     * to maxlen characters. The last character read is always a nul
     * terminator. Returns true on success and false on failure.
     */
    bool tryReadString(char *str, Addr addr, size_t maxlen) const;

    /**
     * Same as tryReadString, but insists on success.
     */
    void
    readString(char *str, Addr addr, size_t maxlen) const
    {
        if (!tryReadString(str, addr, maxlen))
            fatal("readString(%#x, ...) failed", addr);
    }
};


template <typename T>
T
PortProxy::read(Addr address) const
{
    T data;
    readBlob(address, &data, sizeof(T));
    return data;
}

template <typename T>
void
PortProxy::write(Addr address, const T &data) const
{
    writeBlob(address, &data, sizeof(T));
}

template <typename T>
T
PortProxy::read(Addr address, ByteOrder byte_order) const
{
    T data;
    readBlob(address, &data, sizeof(T));
    return gtoh(data, byte_order);
}

template <typename T>
void
PortProxy::write(Addr address, T data, ByteOrder byte_order) const
{
    data = htog(data, byte_order);
    writeBlob(address, &data, sizeof(T));
}

#endif // __MEM_PORT_PROXY_HH__