locked_mem.hh revision 5715:e8c1d4e669a7 
1/*
2 * Copyright (c) 2006-2007 The Regents of The University of Michigan
3 * All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions are
7 * met: redistributions of source code must retain the above copyright
8 * notice, this list of conditions and the following disclaimer;
9 * redistributions in binary form must reproduce the above copyright
10 * notice, this list of conditions and the following disclaimer in the
11 * documentation and/or other materials provided with the distribution;
12 * neither the name of the copyright holders nor the names of its
13 * contributors may be used to endorse or promote products derived from
14 * this software without specific prior written permission.
15 *
16 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
17 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
18 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
19 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
20 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
21 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
22 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
23 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
24 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
25 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
26 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
27 *
28 * Authors: Steve Reinhardt
29 */
30
31#ifndef __ARCH_MIPS_LOCKED_MEM_HH__
32#define __ARCH_MIPS_LOCKED_MEM_HH__
33
34/**
35 * @file
36 *
37 * ISA-specific helper functions for locked memory accesses.
38 */
39
40#include "arch/isa_traits.hh"
41#include "base/misc.hh"
42#include "base/trace.hh"
43#include "mem/request.hh"
44
45
46namespace MipsISA
47{
48template <class XC>
49inline void
50handleLockedRead(XC *xc, Request *req)
51{
52    xc->setMiscRegNoEffect(LLAddr, req->getPaddr() & ~0xf);
53    xc->setMiscRegNoEffect(LLFlag, true);
54    DPRINTF(LLSC, "[tid:%i]: Load-Link Flag Set & Load-Link Address set to %x.\n",
55            req->threadId(), req->getPaddr() & ~0xf);
56}
57
58
59template <class XC>
60inline bool
61handleLockedWrite(XC *xc, Request *req)
62{
63    if (req->isUncacheable()) {
64        // Funky Turbolaser mailbox access...don't update
65        // result register (see stq_c in decoder.isa)
66        req->setExtraData(2);
67    } else {
68        // standard store conditional
69        bool lock_flag = xc->readMiscRegNoEffect(LLFlag);
70        Addr lock_addr = xc->readMiscRegNoEffect(LLAddr);
71
72        if (!lock_flag || (req->getPaddr() & ~0xf) != lock_addr) {
73            // Lock flag not set or addr mismatch in CPU;
74            // don't even bother sending to memory system
75            req->setExtraData(0);
76            xc->setMiscRegNoEffect(LLFlag, false);
77
78            // the rest of this code is not architectural;
79            // it's just a debugging aid to help detect
80            // livelock by warning on long sequences of failed
81            // store conditionals
82            int stCondFailures = xc->readStCondFailures();
83            stCondFailures++;
84            xc->setStCondFailures(stCondFailures);
85            if (stCondFailures % 10 == 0) {
86                warn("%i: context %d: %d consecutive "
87                     "store conditional failures\n",
88                     curTick, xc->contextId(), stCondFailures);
89            }
90
91            if (stCondFailures == 5000) {
92                panic("Max (5000) Store Conditional Fails Reached. Check Code For Deadlock.\n");
93            }
94
95            if (!lock_flag){
96                DPRINTF(LLSC, "[tid:%i]: Lock Flag Set, Store Conditional Failed.\n",
97                        req->threadId());
98            } else if ((req->getPaddr() & ~0xf) != lock_addr) {
99                DPRINTF(LLSC, "[tid:%i]: Load-Link Address Mismatch, Store Conditional Failed.\n",
100                        req->threadId());
101            }
102            // store conditional failed already, so don't issue it to mem
103            return false;
104        }
105    }
106
107    return true;
108}
109
110
111} // namespace MipsISA
112
113#endif
114