summaryrefslogtreecommitdiff
path: root/src/cpu/simple/atomic.hh
blob: 68412510660c6939ff59c883e71f0c1e4f7c08a1 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
/*
 * Copyright (c) 2012 ARM Limited
 * All rights reserved.
 *
 * The license below extends only to copyright in the software and shall
 * not be construed as granting a license to any other intellectual
 * property including but not limited to intellectual property relating
 * to a hardware implementation of the functionality of the software
 * licensed hereunder.  You may use the software subject to the license
 * terms below provided that you ensure that this notice is replicated
 * unmodified and in its entirety in all distributions of the software,
 * modified or unmodified, in source code or in binary form.
 *
 * Copyright (c) 2002-2005 The Regents of The University of Michigan
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are
 * met: redistributions of source code must retain the above copyright
 * notice, this list of conditions and the following disclaimer;
 * redistributions in binary form must reproduce the above copyright
 * notice, this list of conditions and the following disclaimer in the
 * documentation and/or other materials provided with the distribution;
 * neither the name of the copyright holders nor the names of its
 * contributors may be used to endorse or promote products derived from
 * this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 *
 * Authors: Steve Reinhardt
 */

#ifndef __CPU_SIMPLE_ATOMIC_HH__
#define __CPU_SIMPLE_ATOMIC_HH__

#include "cpu/simple/base.hh"
#include "params/AtomicSimpleCPU.hh"

class AtomicSimpleCPU : public BaseSimpleCPU
{
  public:

    AtomicSimpleCPU(AtomicSimpleCPUParams *params);
    virtual ~AtomicSimpleCPU();

    virtual void init();

  private:

    struct TickEvent : public Event
    {
        AtomicSimpleCPU *cpu;

        TickEvent(AtomicSimpleCPU *c);
        void process();
        const char *description() const;
    };

    TickEvent tickEvent;

    const int width;
    bool locked;
    const bool simulate_data_stalls;
    const bool simulate_inst_stalls;

    /**
     * Drain manager to use when signaling drain completion
     *
     * This pointer is non-NULL when draining and NULL otherwise.
     */
    DrainManager *drain_manager;

    // main simulation loop (one cycle)
    void tick();

    /**
     * Check if a system is in a drained state.
     *
     * We need to drain if:
     * <ul>
     * <li>We are in the middle of a microcode sequence as some CPUs
     *     (e.g., HW accelerated CPUs) can't be started in the middle
     *     of a gem5 microcode sequence.
     *
     * <li>The CPU is in a LLSC region. This shouldn't normally happen
     *     as these are executed atomically within a single tick()
     *     call. The only way this can happen at the moment is if
     *     there is an event in the PC event queue that affects the
     *     CPU state while it is in an LLSC region.
     *
     * <li>Stay at PC is true.
     * </ul>
     */
    bool isDrained() {
        return microPC() == 0 &&
            !locked &&
            !stayAtPC;
    }

    /**
     * Try to complete a drain request.
     *
     * @returns true if the CPU is drained, false otherwise.
     */
    bool tryCompleteDrain();

    /**
     * An AtomicCPUPort overrides the default behaviour of the
     * recvAtomic and ignores the packet instead of panicking.
     */
    class AtomicCPUPort : public CpuPort
    {

      public:

        AtomicCPUPort(const std::string &_name, BaseCPU* _cpu)
            : CpuPort(_name, _cpu)
        { }

      protected:

        virtual Tick recvAtomicSnoop(PacketPtr pkt)
        {
            // Snooping a coherence request, just return
            return 0;
        }

    };

    AtomicCPUPort icachePort;
    AtomicCPUPort dcachePort;

    bool fastmem;
    Request ifetch_req;
    Request data_read_req;
    Request data_write_req;

    bool dcache_access;
    Tick dcache_latency;

  protected:

    /** Return a reference to the data port. */
    virtual CpuPort &getDataPort() { return dcachePort; }

    /** Return a reference to the instruction port. */
    virtual CpuPort &getInstPort() { return icachePort; }

  public:

    unsigned int drain(DrainManager *drain_manager);
    void drainResume();

    void switchOut();
    void takeOverFrom(BaseCPU *oldCPU);

    virtual void activateContext(ThreadID thread_num, Cycles delay);
    virtual void suspendContext(ThreadID thread_num);

    Fault readMem(Addr addr, uint8_t *data, unsigned size, unsigned flags);

    Fault writeMem(uint8_t *data, unsigned size,
                   Addr addr, unsigned flags, uint64_t *res);

    /**
     * Print state of address in memory system via PrintReq (for
     * debugging).
     */
    void printAddr(Addr a);
};

#endif // __CPU_SIMPLE_ATOMIC_HH__