timing.hh revision 10407 
1/*
2 * Copyright (c) 2012-2013 ARM Limited
3 * All rights reserved
4 *
5 * The license below extends only to copyright in the software and shall
6 * not be construed as granting a license to any other intellectual
7 * property including but not limited to intellectual property relating
8 * to a hardware implementation of the functionality of the software
9 * licensed hereunder.  You may use the software subject to the license
10 * terms below provided that you ensure that this notice is replicated
11 * unmodified and in its entirety in all distributions of the software,
12 * modified or unmodified, in source code or in binary form.
13 *
14 * Copyright (c) 2002-2005 The Regents of The University of Michigan
15 * All rights reserved.
16 *
17 * Redistribution and use in source and binary forms, with or without
18 * modification, are permitted provided that the following conditions are
19 * met: redistributions of source code must retain the above copyright
20 * notice, this list of conditions and the following disclaimer;
21 * redistributions in binary form must reproduce the above copyright
22 * notice, this list of conditions and the following disclaimer in the
23 * documentation and/or other materials provided with the distribution;
24 * neither the name of the copyright holders nor the names of its
25 * contributors may be used to endorse or promote products derived from
26 * this software without specific prior written permission.
27 *
28 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
29 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
30 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
31 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
32 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
33 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
34 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
35 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
36 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
37 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
38 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
39 *
40 * Authors: Steve Reinhardt
41 */
42
43#ifndef __CPU_SIMPLE_TIMING_HH__
44#define __CPU_SIMPLE_TIMING_HH__
45
46#include "cpu/simple/base.hh"
47#include "cpu/translation.hh"
48#include "params/TimingSimpleCPU.hh"
49
50class TimingSimpleCPU : public BaseSimpleCPU
51{
52  public:
53
54    TimingSimpleCPU(TimingSimpleCPUParams * params);
55    virtual ~TimingSimpleCPU();
56
57    virtual void init();
58
59  private:
60
61    /*
62     * If an access needs to be broken into fragments, currently at most two,
63     * the the following two classes are used as the sender state of the
64     * packets so the CPU can keep track of everything. In the main packet
65     * sender state, there's an array with a spot for each fragment. If a
66     * fragment has already been accepted by the CPU, aka isn't waiting for
67     * a retry, it's pointer is NULL. After each fragment has successfully
68     * been processed, the "outstanding" counter is decremented. Once the
69     * count is zero, the entire larger access is complete.
70     */
71    class SplitMainSenderState : public Packet::SenderState
72    {
73      public:
74        int outstanding;
75        PacketPtr fragments[2];
76
77        int
78        getPendingFragment()
79        {
80            if (fragments[0]) {
81                return 0;
82            } else if (fragments[1]) {
83                return 1;
84            } else {
85                return -1;
86            }
87        }
88    };
89
90    class SplitFragmentSenderState : public Packet::SenderState
91    {
92      public:
93        SplitFragmentSenderState(PacketPtr _bigPkt, int _index) :
94            bigPkt(_bigPkt), index(_index)
95        {}
96        PacketPtr bigPkt;
97        int index;
98
99        void
100        clearFromParent()
101        {
102            SplitMainSenderState * main_send_state =
103                dynamic_cast<SplitMainSenderState *>(bigPkt->senderState);
104            main_send_state->fragments[index] = NULL;
105        }
106    };
107
108    class FetchTranslation : public BaseTLB::Translation
109    {
110      protected:
111        TimingSimpleCPU *cpu;
112
113      public:
114        FetchTranslation(TimingSimpleCPU *_cpu)
115            : cpu(_cpu)
116        {}
117
118        void
119        markDelayed()
120        {
121            assert(cpu->_status == BaseSimpleCPU::Running);
122            cpu->_status = ITBWaitResponse;
123        }
124
125        void
126        finish(const Fault &fault, RequestPtr req, ThreadContext *tc,
127               BaseTLB::Mode mode)
128        {
129            cpu->sendFetch(fault, req, tc);
130        }
131    };
132    FetchTranslation fetchTranslation;
133
134    void sendData(RequestPtr req, uint8_t *data, uint64_t *res, bool read);
135    void sendSplitData(RequestPtr req1, RequestPtr req2, RequestPtr req,
136                       uint8_t *data, bool read);
137
138    void translationFault(const Fault &fault);
139
140    void buildPacket(PacketPtr &pkt, RequestPtr req, bool read);
141    void buildSplitPacket(PacketPtr &pkt1, PacketPtr &pkt2,
142            RequestPtr req1, RequestPtr req2, RequestPtr req,
143            uint8_t *data, bool read);
144
145    bool handleReadPacket(PacketPtr pkt);
146    // This function always implicitly uses dcache_pkt.
147    bool handleWritePacket();
148
149    /**
150     * A TimingCPUPort overrides the default behaviour of the
151     * recvTiming and recvRetry and implements events for the
152     * scheduling of handling of incoming packets in the following
153     * cycle.
154     */
155    class TimingCPUPort : public MasterPort
156    {
157      public:
158
159        TimingCPUPort(const std::string& _name, TimingSimpleCPU* _cpu)
160            : MasterPort(_name, _cpu), cpu(_cpu), retryEvent(this)
161        { }
162
163      protected:
164
165        /**
166         * Snooping a coherence request, do nothing.
167         */
168        virtual void recvTimingSnoopReq(PacketPtr pkt) {}
169
170        TimingSimpleCPU* cpu;
171
172        struct TickEvent : public Event
173        {
174            PacketPtr pkt;
175            TimingSimpleCPU *cpu;
176
177            TickEvent(TimingSimpleCPU *_cpu) : pkt(NULL), cpu(_cpu) {}
178            const char *description() const { return "Timing CPU tick"; }
179            void schedule(PacketPtr _pkt, Tick t);
180        };
181
182        EventWrapper<MasterPort, &MasterPort::sendRetry> retryEvent;
183    };
184
185    class IcachePort : public TimingCPUPort
186    {
187      public:
188
189        IcachePort(TimingSimpleCPU *_cpu)
190            : TimingCPUPort(_cpu->name() + ".icache_port", _cpu),
191              tickEvent(_cpu)
192        { }
193
194      protected:
195
196        virtual bool recvTimingResp(PacketPtr pkt);
197
198        virtual void recvRetry();
199
200        struct ITickEvent : public TickEvent
201        {
202
203            ITickEvent(TimingSimpleCPU *_cpu)
204                : TickEvent(_cpu) {}
205            void process();
206            const char *description() const { return "Timing CPU icache tick"; }
207        };
208
209        ITickEvent tickEvent;
210
211    };
212
213    class DcachePort : public TimingCPUPort
214    {
215      public:
216
217        DcachePort(TimingSimpleCPU *_cpu)
218            : TimingCPUPort(_cpu->name() + ".dcache_port", _cpu),
219              tickEvent(_cpu)
220        {
221           cacheBlockMask = ~(cpu->cacheLineSize() - 1);
222        }
223
224        Addr cacheBlockMask;
225      protected:
226
227        /** Snoop a coherence request, we need to check if this causes
228         * a wakeup event on a cpu that is monitoring an address
229         */
230        virtual void recvTimingSnoopReq(PacketPtr pkt);
231
232        virtual bool recvTimingResp(PacketPtr pkt);
233
234        virtual void recvRetry();
235
236        struct DTickEvent : public TickEvent
237        {
238            DTickEvent(TimingSimpleCPU *_cpu)
239                : TickEvent(_cpu) {}
240            void process();
241            const char *description() const { return "Timing CPU dcache tick"; }
242        };
243
244        DTickEvent tickEvent;
245
246    };
247
248    IcachePort icachePort;
249    DcachePort dcachePort;
250
251    PacketPtr ifetch_pkt;
252    PacketPtr dcache_pkt;
253
254    Tick previousCycle;
255
256  protected:
257
258     /** Return a reference to the data port. */
259    virtual MasterPort &getDataPort() { return dcachePort; }
260
261    /** Return a reference to the instruction port. */
262    virtual MasterPort &getInstPort() { return icachePort; }
263
264  public:
265
266    unsigned int drain(DrainManager *drain_manager);
267    void drainResume();
268
269    void switchOut();
270    void takeOverFrom(BaseCPU *oldCPU);
271
272    void verifyMemoryMode() const;
273
274    virtual void activateContext(ThreadID thread_num);
275    virtual void suspendContext(ThreadID thread_num);
276
277    Fault readMem(Addr addr, uint8_t *data, unsigned size, unsigned flags);
278
279    Fault writeMem(uint8_t *data, unsigned size,
280                   Addr addr, unsigned flags, uint64_t *res);
281
282    void fetch();
283    void sendFetch(const Fault &fault, RequestPtr req, ThreadContext *tc);
284    void completeIfetch(PacketPtr );
285    void completeDataAccess(PacketPtr pkt);
286    void advanceInst(const Fault &fault);
287
288    /** This function is used by the page table walker to determine if it could
289     * translate the a pending request or if the underlying request has been
290     * squashed. This always returns false for the simple timing CPU as it never
291     * executes any instructions speculatively.
292     * @ return Is the current instruction squashed?
293     */
294    bool isSquashed() const { return false; }
295
296    /**
297     * Print state of address in memory system via PrintReq (for
298     * debugging).
299     */
300    void printAddr(Addr a);
301
302    /**
303     * Finish a DTB translation.
304     * @param state The DTB translation state.
305     */
306    void finishTranslation(WholeTranslationState *state);
307
308  private:
309
310    typedef EventWrapper<TimingSimpleCPU, &TimingSimpleCPU::fetch> FetchEvent;
311    FetchEvent fetchEvent;
312
313    struct IprEvent : Event {
314        Packet *pkt;
315        TimingSimpleCPU *cpu;
316        IprEvent(Packet *_pkt, TimingSimpleCPU *_cpu, Tick t);
317        virtual void process();
318        virtual const char *description() const;
319    };
320
321    /**
322     * Check if a system is in a drained state.
323     *
324     * We need to drain if:
325     * <ul>
326     * <li>We are in the middle of a microcode sequence as some CPUs
327     *     (e.g., HW accelerated CPUs) can't be started in the middle
328     *     of a gem5 microcode sequence.
329     *
330     * <li>Stay at PC is true.
331     *
332     * <li>A fetch event is scheduled. Normally this would never be the
333     *     case with microPC() == 0, but right after a context is
334     *     activated it can happen.
335     * </ul>
336     */
337    bool isDrained() {
338        return microPC() == 0 && !stayAtPC && !fetchEvent.scheduled();
339    }
340
341    /**
342     * Try to complete a drain request.
343     *
344     * @returns true if the CPU is drained, false otherwise.
345     */
346    bool tryCompleteDrain();
347
348    /**
349     * Drain manager to use when signaling drain completion
350     *
351     * This pointer is non-NULL when draining and NULL otherwise.
352     */
353    DrainManager *drainManager;
354};
355
356#endif // __CPU_SIMPLE_TIMING_HH__
357