1/*
2 * Copyright (c) 2012-2013, 2015, 2018 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_ATOMIC_HH__
44#define __CPU_SIMPLE_ATOMIC_HH__
45
46#include "cpu/simple/base.hh"
47#include "cpu/simple/exec_context.hh"
48#include "mem/request.hh"
49#include "params/AtomicSimpleCPU.hh"
50#include "sim/probe/probe.hh"
51
52class AtomicSimpleCPU : public BaseSimpleCPU
53{
54 public:
55
56 AtomicSimpleCPU(AtomicSimpleCPUParams *params);
57 virtual ~AtomicSimpleCPU();
58
59 void init() override;
60
61 protected:
62
63 EventFunctionWrapper tickEvent;
64
65 const int width;
66 bool locked;
67 const bool simulate_data_stalls;
68 const bool simulate_inst_stalls;
69
70 // main simulation loop (one cycle)
71 void tick();
72
73 /**
74 * Check if a system is in a drained state.
75 *
76 * We need to drain if:
77 * <ul>
78 * <li>We are in the middle of a microcode sequence as some CPUs
79 * (e.g., HW accelerated CPUs) can't be started in the middle
80 * of a gem5 microcode sequence.
81 *
82 * <li>The CPU is in a LLSC region. This shouldn't normally happen
83 * as these are executed atomically within a single tick()
84 * call. The only way this can happen at the moment is if
85 * there is an event in the PC event queue that affects the
86 * CPU state while it is in an LLSC region.
87 *
88 * <li>Stay at PC is true.
89 * </ul>
90 */
91 bool isCpuDrained() const {
92 SimpleExecContext &t_info = *threadInfo[curThread];
93
94 return t_info.thread->microPC() == 0 &&
95 !locked &&
96 !t_info.stayAtPC;
97 }
98
99 /**
100 * Try to complete a drain request.
101 *
102 * @returns true if the CPU is drained, false otherwise.
103 */
104 bool tryCompleteDrain();
105
106 virtual Tick sendPacket(MasterPort &port, const PacketPtr &pkt);
107
108 /**
109 * An AtomicCPUPort overrides the default behaviour of the
110 * recvAtomicSnoop and ignores the packet instead of panicking. It
111 * also provides an implementation for the purely virtual timing
112 * functions and panics on either of these.
113 */
114 class AtomicCPUPort : public MasterPort
115 {
116
117 public:
118
119 AtomicCPUPort(const std::string &_name, BaseSimpleCPU* _cpu)
120 : MasterPort(_name, _cpu)
121 { }
122
123 protected:
124
125 bool recvTimingResp(PacketPtr pkt)
126 {
127 panic("Atomic CPU doesn't expect recvTimingResp!\n");
128 return true;
129 }
130
131 void recvReqRetry()
132 {
133 panic("Atomic CPU doesn't expect recvRetry!\n");
134 }
135
136 };
137
138 class AtomicCPUDPort : public AtomicCPUPort
139 {
140
141 public:
142 AtomicCPUDPort(const std::string &_name, BaseSimpleCPU* _cpu)
143 : AtomicCPUPort(_name, _cpu), cpu(_cpu)
144 {
145 cacheBlockMask = ~(cpu->cacheLineSize() - 1);
146 }
147
148 bool isSnooping() const { return true; }
149
150 Addr cacheBlockMask;
151 protected:
152 BaseSimpleCPU *cpu;
153
154 virtual Tick recvAtomicSnoop(PacketPtr pkt);
155 virtual void recvFunctionalSnoop(PacketPtr pkt);
156 };
157
158
159 AtomicCPUPort icachePort;
160 AtomicCPUDPort dcachePort;
161
162
163 RequestPtr ifetch_req;
164 RequestPtr data_read_req;
165 RequestPtr data_write_req;
166 RequestPtr data_amo_req;
167
168 bool dcache_access;
169 Tick dcache_latency;
170
171 /** Probe Points. */
172 ProbePointArg<std::pair<SimpleThread*, const StaticInstPtr>> *ppCommit;
173
174 protected:
175
176 /** Return a reference to the data port. */
177 Port &getDataPort() override { return dcachePort; }
178
179 /** Return a reference to the instruction port. */
180 Port &getInstPort() override { return icachePort; }
181
182 /** Perform snoop for other cpu-local thread contexts. */
183 void threadSnoop(PacketPtr pkt, ThreadID sender);
184
185 public:
186
187 DrainState drain() override;
188 void drainResume() override;
189
190 void switchOut() override;
191 void takeOverFrom(BaseCPU *oldCPU) override;
192
193 void verifyMemoryMode() const override;
194
195 void activateContext(ThreadID thread_num) override;
196 void suspendContext(ThreadID thread_num) override;
197
198 /**
199 * Helper function used to set up the request for a single fragment of a
200 * memory access.
201 *
202 * Takes care of setting up the appropriate byte-enable mask for the
203 * fragment, given the mask for the entire memory access.
204 *
205 * @param req Pointer to the Request object to populate.
206 * @param frag_addr Start address of the fragment.
207 * @param size Total size of the memory access in bytes.
208 * @param flags Request flags.
209 * @param byte_enable Byte-enable mask for the entire memory access.
210 * @param[out] frag_size Fragment size.
211 * @param[in,out] size_left Size left to be processed in the memory access.
212 * @return True if the byte-enable mask for the fragment is not all-false.
213 */
214 bool genMemFragmentRequest(const RequestPtr& req, Addr frag_addr,
215 int size, Request::Flags flags,
216 const std::vector<bool>& byte_enable,
217 int& frag_size, int& size_left) const;
218
219 Fault readMem(Addr addr, uint8_t *data, unsigned size,
220 Request::Flags flags,
221 const std::vector<bool>& byteEnable = std::vector<bool>())
222 override;
223
224 Fault writeMem(uint8_t *data, unsigned size,
225 Addr addr, Request::Flags flags, uint64_t *res,
226 const std::vector<bool>& byteEnable = std::vector<bool>())
227 override;
228
229 Fault amoMem(Addr addr, uint8_t* data, unsigned size,
230 Request::Flags flags, AtomicOpFunctorPtr amo_op) override;
231
232 void regProbePoints() override;
233
234 /**
235 * Print state of address in memory system via PrintReq (for
236 * debugging).
237 */
238 void printAddr(Addr a);
239};
240
241#endif // __CPU_SIMPLE_ATOMIC_HH__