locked_mem.hh revision 6330:786136379872 
1/*
2 * Copyright (c) 2006 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_ALPHA_LOCKED_MEM_HH__
32#define __ARCH_ALPHA_LOCKED_MEM_HH__
33
34/**
35 * @file
36 *
37 * ISA-specific helper functions for locked memory accesses.
38 *
39 * Note that these functions are not embedded in the ISA description
40 * because they operate on the *physical* address rather than the
41 * virtual address.  In the current M5 design, the physical address is
42 * not accessible from the ISA description, only from the CPU model.
43 * Thus the CPU is responsible for calling back to the ISA (here)
44 * after the address translation has been performed to allow the ISA
45 * to do these manipulations based on the physical address.
46 */
47
48#include "arch/alpha/registers.hh"
49#include "base/misc.hh"
50#include "mem/request.hh"
51
52namespace AlphaISA {
53
54template <class XC>
55inline void
56handleLockedRead(XC *xc, Request *req)
57{
58    xc->setMiscRegNoEffect(MISCREG_LOCKADDR, req->getPaddr() & ~0xf);
59    xc->setMiscRegNoEffect(MISCREG_LOCKFLAG, true);
60}
61
62
63template <class XC>
64inline bool
65handleLockedWrite(XC *xc, Request *req)
66{
67    if (req->isUncacheable()) {
68        // Funky Turbolaser mailbox access...don't update
69        // result register (see stq_c in decoder.isa)
70        req->setExtraData(2);
71    } else {
72        // standard store conditional
73        bool lock_flag = xc->readMiscRegNoEffect(MISCREG_LOCKFLAG);
74        Addr lock_addr = xc->readMiscRegNoEffect(MISCREG_LOCKADDR);
75        if (!lock_flag || (req->getPaddr() & ~0xf) != lock_addr) {
76            // Lock flag not set or addr mismatch in CPU;
77            // don't even bother sending to memory system
78            req->setExtraData(0);
79            xc->setMiscRegNoEffect(MISCREG_LOCKFLAG, false);
80            // the rest of this code is not architectural;
81            // it's just a debugging aid to help detect
82            // livelock by warning on long sequences of failed
83            // store conditionals
84            int stCondFailures = xc->readStCondFailures();
85            stCondFailures++;
86            xc->setStCondFailures(stCondFailures);
87            if (stCondFailures % 100000 == 0) {
88                warn("context %d: %d consecutive "
89                     "store conditional failures\n",
90                     xc->contextId(), stCondFailures);
91            }
92
93            // store conditional failed already, so don't issue it to mem
94            return false;
95        }
96    }
97
98    return true;
99}
100
101} // namespace AlphaISA
102
103#endif // __ARCH_ALPHA_LOCKED_MEM_HH__
104