1/*
2 * Copyright (c) 2012-2013, 2015 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: Erik Hallnor
41 */
42
43/**
44 * @file
45 * Miss Status and Handling Register (MSHR) declaration.
46 */
47
48#ifndef __MEM_CACHE_MSHR_HH__
49#define __MEM_CACHE_MSHR_HH__
50
51#include <list>
52
53#include "base/printable.hh"
54#include "mem/packet.hh"
55
56class CacheBlk;
57class MSHRQueue;
58
59/**
60 * Miss Status and handling Register. This class keeps all the information
61 * needed to handle a cache miss including a list of target requests.
62 * @sa \ref gem5MemorySystem "gem5 Memory System"
63 */
64class MSHR : public Packet::SenderState, public Printable
65{
66
67 /**
68 * Consider the MSHRQueue a friend to avoid making everything public
69 */
70 friend class MSHRQueue;
71
72 private:
73
74 /** Cycle when ready to issue */
75 Tick readyTime;
76
77 /** True if the request is uncacheable */
78 bool _isUncacheable;
79
80 /** Flag set by downstream caches */
81 bool downstreamPending;
82
83 /** Will we have a dirty copy after this request? */
84 bool pendingDirty;
85
86 /** Did we snoop an invalidate while waiting for data? */
87 bool postInvalidate;
88
89 /** Did we snoop a read while waiting for data? */
90 bool postDowngrade;
91
92 public:
93
94 class Target {
95 public:
96
97 enum Source {
98 FromCPU,
99 FromSnoop,
100 FromPrefetcher
101 };
102
103 const Tick recvTime; //!< Time when request was received (for stats)
104 const Tick readyTime; //!< Time when request is ready to be serviced
105 const Counter order; //!< Global order (for memory consistency mgmt)
106 const PacketPtr pkt; //!< Pending request packet.
107 const Source source; //!< Request from cpu, memory, or prefetcher?
108 const bool markedPending; //!< Did we mark upstream MSHR
109 //!< as downstreamPending?
110
111 Target(PacketPtr _pkt, Tick _readyTime, Counter _order,
112 Source _source, bool _markedPending)
113 : recvTime(curTick()), readyTime(_readyTime), order(_order),
114 pkt(_pkt), source(_source), markedPending(_markedPending)
115 {}
116 };
117
118 class TargetList : public std::list<Target> {
119
120 public:
121 bool needsExclusive;
122 bool hasUpgrade;
123
124 TargetList();
125 void resetFlags() { needsExclusive = hasUpgrade = false; }
126 bool isReset() const { return !needsExclusive && !hasUpgrade; }
127 void add(PacketPtr pkt, Tick readyTime, Counter order,
128 Target::Source source, bool markPending);
129 void replaceUpgrades();
130 void clearDownstreamPending();
131 bool checkFunctional(PacketPtr pkt);
132 void print(std::ostream &os, int verbosity,
133 const std::string &prefix) const;
134 };
135
136 /** A list of MSHRs. */
137 typedef std::list<MSHR *> List;
138 /** MSHR list iterator. */
139 typedef List::iterator Iterator;
140 /** MSHR list const_iterator. */
141 typedef List::const_iterator ConstIterator;
142
143 /** Pointer to queue containing this MSHR. */
144 MSHRQueue *queue;
145
146 /** Order number assigned by the miss queue. */
147 Counter order;
148
149 /** Block aligned address of the MSHR. */
150 Addr blkAddr;
151
152 /** Block size of the cache. */
153 unsigned blkSize;
154
155 /** True if the request targets the secure memory space. */
156 bool isSecure;
157
158 /** True if the request has been sent to the bus. */
159 bool inService;
160
161 /** True if the request is just a simple forward from an upper level */
162 bool isForward;
163
164 /** The pending* and post* flags are only valid if inService is
165 * true. Using the accessor functions lets us detect if these
166 * flags are accessed improperly.
167 */
168
169 /** True if we need to get an exclusive copy of the block. */
170 bool needsExclusive() const { return targets.needsExclusive; }
171
172 bool isPendingDirty() const {
173 assert(inService); return pendingDirty;
174 }
175
176 bool hasPostInvalidate() const {
177 assert(inService); return postInvalidate;
178 }
179
180 bool hasPostDowngrade() const {
181 assert(inService); return postDowngrade;
182 }
183
184 /** Thread number of the miss. */
185 ThreadID threadNum;
186
187 private:
188
189 /** Data buffer (if needed). Currently used only for pending
190 * upgrade handling. */
191 uint8_t *data;
192
193 /**
194 * Pointer to this MSHR on the ready list.
195 * @sa MissQueue, MSHRQueue::readyList
196 */
197 Iterator readyIter;
198
199 /**
200 * Pointer to this MSHR on the allocated list.
201 * @sa MissQueue, MSHRQueue::allocatedList
202 */
203 Iterator allocIter;
204
205 /** List of all requests that match the address */
206 TargetList targets;
207
208 TargetList deferredTargets;
209
210 public:
211
212 bool isUncacheable() const { return _isUncacheable; }
213
214 /**
215 * Allocate a miss to this MSHR.
216 * @param blk_addr The address of the block.
217 * @param blk_size The number of bytes to request.
218 * @param pkt The original miss.
219 * @param when_ready When should the MSHR be ready to act upon.
220 * @param _order The logical order of this MSHR
221 */
222 void allocate(Addr blk_addr, unsigned blk_size, PacketPtr pkt,
223 Tick when_ready, Counter _order);
224
225 bool markInService(bool pending_dirty_resp);
226
227 void clearDownstreamPending();
228
229 /**
230 * Mark this MSHR as free.
231 */
232 void deallocate();
233
234 /**
235 * Add a request to the list of targets.
236 * @param target The target.
237 */
238 void allocateTarget(PacketPtr target, Tick when, Counter order);
239 bool handleSnoop(PacketPtr target, Counter order);
240
241 /** A simple constructor. */
242 MSHR();
243
244 /**
245 * Returns the current number of allocated targets.
246 * @return The current number of allocated targets.
247 */
248 int getNumTargets() const
249 { return targets.size() + deferredTargets.size(); }
250
251 /**
252 * Returns true if there are targets left.
253 * @return true if there are targets
254 */
255 bool hasTargets() const { return !targets.empty(); }
256
257 /**
258 * Returns a reference to the first target.
259 * @return A pointer to the first target.
260 */
261 Target *getTarget()
262 {
263 assert(hasTargets());
264 return &targets.front();
265 }
266
267 /**
268 * Pop first target.
269 */
270 void popTarget()
271 {
272 targets.pop_front();
273 }
274
275 bool isForwardNoResponse() const
276 {
277 if (getNumTargets() != 1)
278 return false;
279 const Target *tgt = &targets.front();
280 return tgt->source == Target::FromCPU && !tgt->pkt->needsResponse();
281 }
282
283 bool promoteDeferredTargets();
284
285 void promoteExclusive();
286
287 bool checkFunctional(PacketPtr pkt);
288
289 /**
290 * Prints the contents of this MSHR for debugging.
291 */
292 void print(std::ostream &os,
293 int verbosity = 0,
294 const std::string &prefix = "") const;
295 /**
296 * A no-args wrapper of print(std::ostream...) meant to be
297 * invoked from DPRINTFs avoiding string overheads in fast mode
298 *
299 * @return string with mshr fields + [deferred]targets
300 */
301 std::string print() const;
302};
303
304#endif // __MEM_CACHE_MSHR_HH__