timing.hh revision 9523 
1/*
2 * Copyright (c) 2012 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(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(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 CpuPort
156    {
157      public:
158
159        TimingCPUPort(const std::string& _name, TimingSimpleCPU* _cpu)
160            : CpuPort(_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
222      protected:
223
224        virtual bool recvTimingResp(PacketPtr pkt);
225
226        virtual void recvRetry();
227
228        struct DTickEvent : public TickEvent
229        {
230            DTickEvent(TimingSimpleCPU *_cpu)
231                : TickEvent(_cpu) {}
232            void process();
233            const char *description() const { return "Timing CPU dcache tick"; }
234        };
235
236        DTickEvent tickEvent;
237
238    };
239
240    IcachePort icachePort;
241    DcachePort dcachePort;
242
243    PacketPtr ifetch_pkt;
244    PacketPtr dcache_pkt;
245
246    Tick previousCycle;
247
248  protected:
249
250     /** Return a reference to the data port. */
251    virtual CpuPort &getDataPort() { return dcachePort; }
252
253    /** Return a reference to the instruction port. */
254    virtual CpuPort &getInstPort() { return icachePort; }
255
256  public:
257
258    unsigned int drain(DrainManager *drain_manager);
259    void drainResume();
260
261    void switchOut();
262    void takeOverFrom(BaseCPU *oldCPU);
263
264    void verifyMemoryMode() const;
265
266    virtual void activateContext(ThreadID thread_num, Cycles delay);
267    virtual void suspendContext(ThreadID thread_num);
268
269    Fault readMem(Addr addr, uint8_t *data, unsigned size, unsigned flags);
270
271    Fault writeMem(uint8_t *data, unsigned size,
272                   Addr addr, unsigned flags, uint64_t *res);
273
274    void fetch();
275    void sendFetch(Fault fault, RequestPtr req, ThreadContext *tc);
276    void completeIfetch(PacketPtr );
277    void completeDataAccess(PacketPtr pkt);
278    void advanceInst(Fault fault);
279
280    /** This function is used by the page table walker to determine if it could
281     * translate the a pending request or if the underlying request has been
282     * squashed. This always returns false for the simple timing CPU as it never
283     * executes any instructions speculatively.
284     * @ return Is the current instruction squashed?
285     */
286    bool isSquashed() const { return false; }
287
288    /**
289     * Print state of address in memory system via PrintReq (for
290     * debugging).
291     */
292    void printAddr(Addr a);
293
294    /**
295     * Finish a DTB translation.
296     * @param state The DTB translation state.
297     */
298    void finishTranslation(WholeTranslationState *state);
299
300  private:
301
302    typedef EventWrapper<TimingSimpleCPU, &TimingSimpleCPU::fetch> FetchEvent;
303    FetchEvent fetchEvent;
304
305    struct IprEvent : Event {
306        Packet *pkt;
307        TimingSimpleCPU *cpu;
308        IprEvent(Packet *_pkt, TimingSimpleCPU *_cpu, Tick t);
309        virtual void process();
310        virtual const char *description() const;
311    };
312
313    /**
314     * Check if a system is in a drained state.
315     *
316     * We need to drain if:
317     * <ul>
318     * <li>We are in the middle of a microcode sequence as some CPUs
319     *     (e.g., HW accelerated CPUs) can't be started in the middle
320     *     of a gem5 microcode sequence.
321     *
322     * <li>Stay at PC is true.
323     * </ul>
324     */
325    bool isDrained() {
326        return microPC() == 0 &&
327            !stayAtPC;
328    }
329
330    /**
331     * Try to complete a drain request.
332     *
333     * @returns true if the CPU is drained, false otherwise.
334     */
335    bool tryCompleteDrain();
336
337    /**
338     * Drain manager to use when signaling drain completion
339     *
340     * This pointer is non-NULL when draining and NULL otherwise.
341     */
342    DrainManager *drainManager;
343};
344
345#endif // __CPU_SIMPLE_TIMING_HH__
346