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 now.  @todo fix later
  62 #define NUM_MEM_CMDS 1 << 11
  63 /**
  64  * A Packet is used to encapsulate a transfer between two objects in
  65  * the memory system (e.g., the L1 and L2 cache).  (In contrast, a
  66  * single Request travels all the way from the requester to the
  67  * ultimate destination and back, possibly being conveyed by several
  68  * different Packets along the way.)
  69  */
  70 class Packet
  71 {
  72   public:
  73     /** Temporary FLAGS field until cache gets working, this should be in coherence/sender state. */
  74     uint64_t flags;
  75
  76   private:
  77    /** A pointer to the data being transfered.  It can be differnt
  78     *    sizes at each level of the heirarchy so it belongs in the
  79     *    packet, not request. This may or may not be populated when a
  80     *    responder recieves the packet. If not populated it memory
  81     *    should be allocated.
  82     */
  83     PacketDataPtr data;
  84
  85     /** Is the data pointer set to a value that shouldn't be freed
  86      *   when the packet is destroyed? */
  87     bool staticData;
  88     /** The data pointer points to a value that should be freed when
  89      *   the packet is destroyed. */
  90     bool dynamicData;
  91     /** the data pointer points to an array (thus delete [] ) needs to
  92      *   be called on it rather than simply delete.*/
  93     bool arrayData;
  94
  95
  96     /** The address of the request.  This address could be virtual or
  97      *   physical, depending on the system configuration. */
  98     Addr addr;
  99
 100      /** The size of the request or transfer. */
 101     int size;
 102
 103     /** Device address (e.g., bus ID) of the source of the
 104      *   transaction. The source is not responsible for setting this
 105      *   field; it is set implicitly by the interconnect when the
 106      *   packet * is first sent.  */
 107     short src;
 108
 109     /** Device address (e.g., bus ID) of the destination of the
 110      *   transaction. The special value Broadcast indicates that the
 111      *   packet should be routed based on its address. This field is
 112      *   initialized in the constructor and is thus always valid
 113      *   (unlike * addr, size, and src). */
 114     short dest;
 115
 116     /** Are the 'addr' and 'size' fields valid? */
 117     bool addrSizeValid;
 118     /** Is the 'src' field valid? */
 119     bool srcValid;
 120
 121
 122   public:
 123
 124     /** Used to calculate latencies for each packet.*/
 125     Tick time;
 126
 127     /** The special destination address indicating that the packet
 128      *   should be routed based on its address. */
 129     static const short Broadcast = -1;
 130
 131     /** A pointer to the original request. */
 132     RequestPtr req;
 133
 134     /** A virtual base opaque structure used to hold coherence-related
 135      *    state.  A specific subclass would be derived from this to
 136      *    carry state specific to a particular coherence protocol.  */
 137     class CoherenceState {
 138       public:
 139         virtual ~CoherenceState() {}
 140     };
 141
 142     /** This packet's coherence state.  Caches should use
 143      *   dynamic_cast<> to cast to the state appropriate for the
 144      *   system's coherence protocol.  */
 145     CoherenceState *coherence;
 146
 147     /** A virtual base opaque structure used to hold state associated
 148      *    with the packet but specific to the sending device (e.g., an
 149      *    MSHR).  A pointer to this state is returned in the packet's
 150      *    response so that the sender can quickly look up the state
 151      *    needed to process it.  A specific subclass would be derived
 152      *    from this to carry state specific to a particular sending
 153      *    device.  */
 154     class SenderState {
 155       public:
 156         virtual ~SenderState() {}
 157     };
 158
 159     /** This packet's sender state.  Devices should use dynamic_cast<>
 160      *   to cast to the state appropriate to the sender. */
 161     SenderState *senderState;
 162
 163   private:
 164     /** List of command attributes. */
 165     // If you add a new CommandAttribute, make sure to increase NUM_MEM_CMDS
 166     // as well.
 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         IsUpgrade       = 1 << 9,
 179         HasData         = 1 << 10
 180     };
 181 //For statistics we need max number of commands, hard code it at
 182 //20 for now.  @todo fix later
 183 #define NUM_MEM_CMDS 1 << 10
 184
 185   public:
 186     /** List of all commands associated with a packet. */
 187     enum Command
 188     {
 189         InvalidCmd      = 0,
 190         ReadReq         = IsRead  | IsRequest | NeedsResponse,
 191         WriteReq        = IsWrite | IsRequest | NeedsResponse | HasData,
 192         WriteReqNoAck   = IsWrite | IsRequest | HasData,
 193         ReadResp        = IsRead  | IsResponse | NeedsResponse | HasData,
 194         WriteResp       = IsWrite | IsResponse | NeedsResponse,
 195         Writeback       = IsWrite | IsRequest | HasData,
 196         SoftPFReq       = IsRead  | IsRequest | IsSWPrefetch | NeedsResponse,
 197         HardPFReq       = IsRead  | IsRequest | IsHWPrefetch | NeedsResponse,
 198         SoftPFResp      = IsRead  | IsResponse | IsSWPrefetch
 199                                 | NeedsResponse | HasData,
 200         HardPFResp      = IsRead  | IsResponse | IsHWPrefetch
 201                                 | NeedsResponse | HasData,
 202         InvalidateReq   = IsInvalidate | IsRequest,
 203         WriteInvalidateReq = IsWrite | IsInvalidate | IsRequest | HasData,
 204         UpgradeReq      = IsInvalidate | IsRequest | IsUpgrade,
 205         ReadExReq       = IsRead | IsInvalidate | IsRequest | NeedsResponse,
 206         ReadExResp      = IsRead | IsInvalidate | IsResponse
 207                                 | NeedsResponse | HasData
 208     };
 209
 210     /** Return the string name of the cmd field (for debugging and
 211      *   tracing). */
 212     const std::string &cmdString() const;
 213
 214     /** Reutrn the string to a cmd given by idx. */
 215     const std::string &cmdIdxToString(Command idx);
 216
 217     /** Return the index of this command. */
 218     inline int cmdToIndex() const { return (int) cmd; }
 219
 220     /** The command field of the packet. */
 221     Command cmd;
 222
 223     bool isRead()        { return (cmd & IsRead)  != 0; }
 224     bool isWrite()       { return (cmd & IsWrite) != 0; }
 225     bool isRequest()     { return (cmd & IsRequest)  != 0; }
 226     bool isResponse()    { return (cmd & IsResponse) != 0; }
 227     bool needsResponse() { return (cmd & NeedsResponse) != 0; }
 228     bool isInvalidate()  { return (cmd & IsInvalidate) != 0; }
 229     bool hasData()       { return (cmd & HasData) != 0; }
 230
 231     bool isCacheFill() { return (flags & CACHE_LINE_FILL) != 0; }
 232     bool isNoAllocate() { return (flags & NO_ALLOCATE) != 0; }
 233     bool isCompressed() { return (flags & COMPRESSED) != 0; }
 234
 235     bool nic_pkt() { assert("Unimplemented\n" && 0); return false; }
 236
 237     /** Possible results of a packet's request. */
 238     enum Result
 239     {
 240         Success,
 241         BadAddress,
 242         Nacked,
 243         Unknown
 244     };
 245
 246     /** The result of this packet's request. */
 247     Result result;
 248
 249     /** Accessor function that returns the source index of the packet. */
 250     short getSrc() const { assert(srcValid); return src; }
 251     void setSrc(short _src) { src = _src; srcValid = true; }
 252
 253     /** Accessor function that returns the destination index of
 254         the packet. */
 255     short getDest() const { return dest; }
 256     void setDest(short _dest) { dest = _dest; }
 257
 258     Addr getAddr() const { assert(addrSizeValid); return addr; }
 259     int getSize() const { assert(addrSizeValid); return size; }
 260     Addr getOffset(int blkSize) const { return addr & (Addr)(blkSize - 1); }
 261
 262     void addrOverride(Addr newAddr) { assert(addrSizeValid); addr = newAddr; }
 263     void cmdOverride(Command newCmd) { cmd = newCmd; }
 264
 265     /** Constructor.  Note that a Request object must be constructed
 266      *   first, but the Requests's physical address and size fields
 267      *   need not be valid. The command and destination addresses
 268      *   must be supplied.  */
 269     Packet(Request *_req, Command _cmd, short _dest)
 270         :  data(NULL), staticData(false), dynamicData(false), arrayData(false),
 271            addr(_req->paddr), size(_req->size), dest(_dest),
 272            addrSizeValid(_req->validPaddr),
 273            srcValid(false),
 274            req(_req), coherence(NULL), senderState(NULL), cmd(_cmd),
 275            result(Unknown)
 276     {
 277         flags = 0;
 278         time = curTick;
 279     }
 280
 281     /** Alternate constructor if you are trying to create a packet with
 282      *  a request that is for a whole block, not the address from the req.
 283      *  this allows for overriding the size/addr of the req.*/
 284     Packet(Request *_req, Command _cmd, short _dest, int _blkSize)
 285         :  data(NULL), staticData(false), dynamicData(false), arrayData(false),
 286            addr(_req->paddr & ~(_blkSize - 1)), size(_blkSize),
 287            dest(_dest),
 288            addrSizeValid(_req->validPaddr), srcValid(false),
 289            req(_req), coherence(NULL), senderState(NULL), cmd(_cmd),
 290            result(Unknown)
 291     {
 292         flags = 0;
 293         time = curTick;
 294     }
 295
 296     /** Destructor. */
 297     ~Packet()
 298     { deleteData(); }
 299
 300     /** Reinitialize packet address and size from the associated
 301      *   Request object, and reset other fields that may have been
 302      *   modified by a previous transaction.  Typically called when a
 303      *   statically allocated Request/Packet pair is reused for
 304      *   multiple transactions. */
 305     void reinitFromRequest() {
 306         assert(req->validPaddr);
 307         addr = req->paddr;
 308         size = req->size;
 309         time = req->time;
 310         addrSizeValid = true;
 311         result = Unknown;
 312         if (dynamicData) {
 313             deleteData();
 314             dynamicData = false;
 315             arrayData = false;
 316         }
 317     }
 318
 319     /** Take a request packet and modify it in place to be suitable
 320      *   for returning as a response to that request.  Used for timing
 321      *   accesses only.  For atomic and functional accesses, the
 322      *   request packet is always implicitly passed back *without*
 323      *   modifying the destination fields, so this function
 324      *   should not be called. */
 325     void makeTimingResponse() {
 326         assert(needsResponse());
 327         assert(isRequest());
 328         int icmd = (int)cmd;
 329         icmd &= ~(IsRequest);
 330         icmd |= IsResponse;
 331         cmd = (Command)icmd;
 332         dest = src;
 333         srcValid = false;
 334     }
 335
 336     /** Take a request packet and modify it in place to be suitable
 337      *   for returning as a response to that request.
 338      */
 339     void makeAtomicResponse() {
 340         assert(needsResponse());
 341         assert(isRequest());
 342         int icmd = (int)cmd;
 343         icmd &= ~(IsRequest);
 344         icmd |= IsResponse;
 345         cmd = (Command)icmd;
 346     }
 347
 348     /** Take a request packet that has been returned as NACKED and modify it so
 349      * that it can be sent out again. Only packets that need a response can be
 350      * NACKED, so verify that that is true. */
 351     void reinitNacked() {
 352         assert(needsResponse() && result == Nacked);
 353         dest =  Broadcast;
 354         result = Unknown;
 355     }
 356
 357
 358     /** Set the data pointer to the following value that should not be freed. */
 359     template <typename T>
 360     void dataStatic(T *p);
 361
 362     /** Set the data pointer to a value that should have delete [] called on it.
 363      */
 364     template <typename T>
 365     void dataDynamicArray(T *p);
 366
 367     /** set the data pointer to a value that should have delete called on it. */
 368     template <typename T>
 369     void dataDynamic(T *p);
 370
 371     /** return the value of what is pointed to in the packet. */
 372     template <typename T>
 373     T get();
 374
 375     /** get a pointer to the data ptr. */
 376     template <typename T>
 377     T* getPtr();
 378
 379     /** set the value in the data pointer to v. */
 380     template <typename T>
 381     void set(T v);
 382
 383     /** delete the data pointed to in the data pointer. Ok to call to matter how
 384      * data was allocted. */
 385     void deleteData();
 386
 387     /** If there isn't data in the packet, allocate some. */
 388     void allocate();
 389
 390     /** Do the packet modify the same addresses. */
 391     bool intersect(Packet *p);
 392 };
 393
 394 bool fixPacket(Packet *func, Packet *timing);
 395 #endif //__MEM_PACKET_HH