src/mem/packet.hh

   1 /*
   2  * Copyright (c) 2006 The Regents of The University of Michigan
   3  * All rights reserved.
   4  *
   5  * Redistribution and use in source and binary forms, with or without
   6  * modification, are permitted provided that the following conditions are
   7  * met: redistributions of source code must retain the above copyright
   8  * notice, this list of conditions and the following disclaimer;
   9  * redistributions in binary form must reproduce the above copyright
  10  * notice, this list of conditions and the following disclaimer in the
  11  * documentation and/or other materials provided with the distribution;
  12  * neither the name of the copyright holders nor the names of its
  13  * contributors may be used to endorse or promote products derived from
  14  * this software without specific prior written permission.
  15  *
  16  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
  17  * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
  18  * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
  19  * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
  20  * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
  21  * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
  22  * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  23  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  24  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  25  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
  26  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  27  *
  28  * Authors: Ron Dreslinski
  29  *          Steve Reinhardt
  30  *          Ali Saidi
  31  */
  32
  33 /**
  34  * @file
  35  * Declaration of the Packet class.
  36  */
  37
  38 #ifndef __MEM_PACKET_HH__
  39 #define __MEM_PACKET_HH__
  40
  41 #include "mem/request.hh"
  42 #include "sim/host.hh"
  43 #include "sim/root.hh"
  44 #include <list>
  45 #include <cassert>
  46
  47 struct Packet;
  48 typedef Packet* PacketPtr;
  49 typedef uint8_t* PacketDataPtr;
  50 typedef std::list<PacketPtr> PacketList;
  51
  52 //Coherence Flags
  53 #define NACKED_LINE 1 << 0
  54 #define SATISFIED 1 << 1
  55 #define SHARED_LINE 1 << 2
  56 #define CACHE_LINE_FILL 1 << 3
  57 #define COMPRESSED 1 << 4
  58 #define NO_ALLOCATE 1 << 5
  59 #define SNOOP_COMMIT 1 << 6
  60
  61 //For statistics we need max number of commands, hard code it at
  62 //20 for now.  @todo fix later
  63 #define NUM_MEM_CMDS 1 << 9
  64
  65 /**
  66  * A Packet is used to encapsulate a transfer between two objects in
  67  * the memory system (e.g., the L1 and L2 cache).  (In contrast, a
  68  * single Request travels all the way from the requester to the
  69  * ultimate destination and back, possibly being conveyed by several
  70  * different Packets along the way.)
  71  */
  72 class Packet
  73 {
  74   public:
  75     /** Temporary FLAGS field until cache gets working, this should be in coherence/sender state. */
  76     uint64_t flags;
  77
  78   private:
  79    /** A pointer to the data being transfered.  It can be differnt
  80     *    sizes at each level of the heirarchy so it belongs in the
  81     *    packet, not request. This may or may not be populated when a
  82     *    responder recieves the packet. If not populated it memory
  83     *    should be allocated.
  84     */
  85     PacketDataPtr data;
  86
  87     /** Is the data pointer set to a value that shouldn't be freed
  88      *   when the packet is destroyed? */
  89     bool staticData;
  90     /** The data pointer points to a value that should be freed when
  91      *   the packet is destroyed. */
  92     bool dynamicData;
  93     /** the data pointer points to an array (thus delete [] ) needs to
  94      *   be called on it rather than simply delete.*/
  95     bool arrayData;
  96
  97
  98     /** The address of the request.  This address could be virtual or
  99      *   physical, depending on the system configuration. */
 100     Addr addr;
 101
 102      /** The size of the request or transfer. */
 103     int size;
 104
 105     /** Device address (e.g., bus ID) of the source of the
 106      *   transaction. The source is not responsible for setting this
 107      *   field; it is set implicitly by the interconnect when the
 108      *   packet * is first sent.  */
 109     short src;
 110
 111     /** Device address (e.g., bus ID) of the destination of the
 112      *   transaction. The special value Broadcast indicates that the
 113      *   packet should be routed based on its address. This field is
 114      *   initialized in the constructor and is thus always valid
 115      *   (unlike * addr, size, and src). */
 116     short dest;
 117
 118     /** Are the 'addr' and 'size' fields valid? */
 119     bool addrSizeValid;
 120     /** Is the 'src' field valid? */
 121     bool srcValid;
 122
 123
 124   public:
 125
 126     /** Used to calculate latencies for each packet.*/
 127     Tick time;
 128
 129     /** The special destination address indicating that the packet
 130      *   should be routed based on its address. */
 131     static const short Broadcast = -1;
 132
 133     /** A pointer to the original request. */
 134     RequestPtr req;
 135
 136     /** A virtual base opaque structure used to hold coherence-related
 137      *    state.  A specific subclass would be derived from this to
 138      *    carry state specific to a particular coherence protocol.  */
 139     class CoherenceState {
 140       public:
 141         virtual ~CoherenceState() {}
 142     };
 143
 144     /** This packet's coherence state.  Caches should use
 145      *   dynamic_cast<> to cast to the state appropriate for the
 146      *   system's coherence protocol.  */
 147     CoherenceState *coherence;
 148
 149     /** A virtual base opaque structure used to hold state associated
 150      *    with the packet but specific to the sending device (e.g., an
 151      *    MSHR).  A pointer to this state is returned in the packet's
 152      *    response so that the sender can quickly look up the state
 153      *    needed to process it.  A specific subclass would be derived
 154      *    from this to carry state specific to a particular sending
 155      *    device.  */
 156     class SenderState {
 157       public:
 158         virtual ~SenderState() {}
 159     };
 160
 161     /** This packet's sender state.  Devices should use dynamic_cast<>
 162      *   to cast to the state appropriate to the sender. */
 163     SenderState *senderState;
 164
 165   private:
 166     /** List of command attributes. */
 167     enum CommandAttribute
 168     {
 169         IsRead          = 1 << 0,
 170         IsWrite         = 1 << 1,
 171         IsPrefetch      = 1 << 2,
 172         IsInvalidate    = 1 << 3,
 173         IsRequest       = 1 << 4,
 174         IsResponse      = 1 << 5,
 175         NeedsResponse   = 1 << 6,
 176         IsSWPrefetch    = 1 << 7,
 177         IsHWPrefetch    = 1 << 8
 178     };
 179
 180   public:
 181     /** List of all commands associated with a packet. */
 182     enum Command
 183     {
 184         InvalidCmd      = 0,
 185         ReadReq         = IsRead  | IsRequest | NeedsResponse,
 186         WriteReq        = IsWrite | IsRequest | NeedsResponse,
 187         WriteReqNoAck   = IsWrite | IsRequest,
 188         ReadResp        = IsRead  | IsResponse | NeedsResponse,
 189         WriteResp       = IsWrite | IsResponse | NeedsResponse,
 190         Writeback       = IsWrite | IsRequest,
 191         SoftPFReq       = IsRead  | IsRequest | IsSWPrefetch | NeedsResponse,
 192         HardPFReq       = IsRead  | IsRequest | IsHWPrefetch | NeedsResponse,
 193         SoftPFResp      = IsRead  | IsResponse | IsSWPrefetch | NeedsResponse,
 194         HardPFResp      = IsRead  | IsResponse | IsHWPrefetch | NeedsResponse,
 195         InvalidateReq   = IsInvalidate | IsRequest,
 196         WriteInvalidateReq = IsWrite | IsInvalidate | IsRequest,
 197         UpgradeReq      = IsInvalidate | IsRequest,
 198         ReadExReq       = IsRead | IsInvalidate | IsRequest | NeedsResponse,
 199         ReadExResp      = IsRead | IsInvalidate | IsResponse | NeedsResponse
 200     };
 201
 202     /** Return the string name of the cmd field (for debugging and
 203      *   tracing). */
 204     const std::string &cmdString() const;
 205
 206     /** Reutrn the string to a cmd given by idx. */
 207     const std::string &cmdIdxToString(Command idx);
 208
 209     /** Return the index of this command. */
 210     inline int cmdToIndex() const { return (int) cmd; }
 211
 212     /** The command field of the packet. */
 213     Command cmd;
 214
 215     bool isRead()        { return (cmd & IsRead)  != 0; }
 216     bool isWrite()       { return (cmd & IsWrite) != 0; }
 217     bool isRequest()     { return (cmd & IsRequest)  != 0; }
 218     bool isResponse()    { return (cmd & IsResponse) != 0; }
 219     bool needsResponse() { return (cmd & NeedsResponse) != 0; }
 220     bool isInvalidate()  { return (cmd & IsInvalidate) != 0; }
 221
 222     bool isCacheFill() { return (flags & CACHE_LINE_FILL) != 0; }
 223     bool isNoAllocate() { return (flags & NO_ALLOCATE) != 0; }
 224     bool isCompressed() { return (flags & COMPRESSED) != 0; }
 225
 226     bool nic_pkt() { assert("Unimplemented\n" && 0); return false; }
 227
 228     /** Possible results of a packet's request. */
 229     enum Result
 230     {
 231         Success,
 232         BadAddress,
 233         Nacked,
 234         Unknown
 235     };
 236
 237     /** The result of this packet's request. */
 238     Result result;
 239
 240     /** Accessor function that returns the source index of the packet. */
 241     short getSrc() const { assert(srcValid); return src; }
 242     void setSrc(short _src) { src = _src; srcValid = true; }
 243
 244     /** Accessor function that returns the destination index of
 245         the packet. */
 246     short getDest() const { return dest; }
 247     void setDest(short _dest) { dest = _dest; }
 248
 249     Addr getAddr() const { assert(addrSizeValid); return addr; }
 250     int getSize() const { assert(addrSizeValid); return size; }
 251     Addr getOffset(int blkSize) const { return addr & (Addr)(blkSize - 1); }
 252
 253     void addrOverride(Addr newAddr) { assert(addrSizeValid); addr = newAddr; }
 254     void cmdOverride(Command newCmd) { cmd = newCmd; }
 255
 256     /** Constructor.  Note that a Request object must be constructed
 257      *   first, but the Requests's physical address and size fields
 258      *   need not be valid. The command and destination addresses
 259      *   must be supplied.  */
 260     Packet(Request *_req, Command _cmd, short _dest)
 261         :  data(NULL), staticData(false), dynamicData(false), arrayData(false),
 262            addr(_req->paddr), size(_req->size), dest(_dest),
 263            addrSizeValid(_req->validPaddr),
 264            srcValid(false),
 265            req(_req), coherence(NULL), senderState(NULL), cmd(_cmd),
 266            result(Unknown)
 267     {
 268         flags = 0;
 269         time = curTick;
 270     }
 271
 272     /** Alternate constructor if you are trying to create a packet with
 273      *  a request that is for a whole block, not the address from the req.
 274      *  this allows for overriding the size/addr of the req.*/
 275     Packet(Request *_req, Command _cmd, short _dest, int _blkSize)
 276         :  data(NULL), staticData(false), dynamicData(false), arrayData(false),
 277            addr(_req->paddr & ~(_blkSize - 1)), size(_blkSize),
 278            dest(_dest),
 279            addrSizeValid(_req->validPaddr), srcValid(false),
 280            req(_req), coherence(NULL), senderState(NULL), cmd(_cmd),
 281            result(Unknown)
 282     {
 283         flags = 0;
 284         time = curTick;
 285     }
 286
 287     /** Destructor. */
 288     ~Packet()
 289     { deleteData(); }
 290
 291     /** Reinitialize packet address and size from the associated
 292      *   Request object, and reset other fields that may have been
 293      *   modified by a previous transaction.  Typically called when a
 294      *   statically allocated Request/Packet pair is reused for
 295      *   multiple transactions. */
 296     void reinitFromRequest() {
 297         assert(req->validPaddr);
 298         addr = req->paddr;
 299         size = req->size;
 300         time = req->time;
 301         addrSizeValid = true;
 302         result = Unknown;
 303         if (dynamicData) {
 304             deleteData();
 305             dynamicData = false;
 306             arrayData = false;
 307         }
 308     }
 309
 310     /** Take a request packet and modify it in place to be suitable
 311      *   for returning as a response to that request.  Used for timing
 312      *   accesses only.  For atomic and functional accesses, the
 313      *   request packet is always implicitly passed back *without*
 314      *   modifying the destination fields, so this function
 315      *   should not be called. */
 316     void makeTimingResponse() {
 317         assert(needsResponse());
 318         assert(isRequest());
 319         int icmd = (int)cmd;
 320         icmd &= ~(IsRequest);
 321         icmd |= IsResponse;
 322         cmd = (Command)icmd;
 323         dest = src;
 324         srcValid = false;
 325     }
 326
 327     /** Take a request packet and modify it in place to be suitable
 328      *   for returning as a response to that request.
 329      */
 330     void makeAtomicResponse() {
 331         assert(needsResponse());
 332         assert(isRequest());
 333         int icmd = (int)cmd;
 334         icmd &= ~(IsRequest);
 335         icmd |= IsResponse;
 336         cmd = (Command)icmd;
 337     }
 338
 339     /** Take a request packet that has been returned as NACKED and modify it so
 340      * that it can be sent out again. Only packets that need a response can be
 341      * NACKED, so verify that that is true. */
 342     void reinitNacked() {
 343         assert(needsResponse() && result == Nacked);
 344         dest =  Broadcast;
 345         result = Unknown;
 346     }
 347
 348
 349     /** Set the data pointer to the following value that should not be freed. */
 350     template <typename T>
 351     void dataStatic(T *p);
 352
 353     /** Set the data pointer to a value that should have delete [] called on it.
 354      */
 355     template <typename T>
 356     void dataDynamicArray(T *p);
 357
 358     /** set the data pointer to a value that should have delete called on it. */
 359     template <typename T>
 360     void dataDynamic(T *p);
 361
 362     /** return the value of what is pointed to in the packet. */
 363     template <typename T>
 364     T get();
 365
 366     /** get a pointer to the data ptr. */
 367     template <typename T>
 368     T* getPtr();
 369
 370     /** set the value in the data pointer to v. */
 371     template <typename T>
 372     void set(T v);
 373
 374     /** delete the data pointed to in the data pointer. Ok to call to matter how
 375      * data was allocted. */
 376     void deleteData();
 377
 378     /** If there isn't data in the packet, allocate some. */
 379     void allocate();
 380
 381     /** Do the packet modify the same addresses. */
 382     bool intersect(Packet *p);
 383 };
 384
 385 bool fixPacket(Packet *func, Packet *timing);
 386 #endif //__MEM_PACKET_HH