1/*
2 * Copyright (c) 2006 The Regents of The University of Michigan
3 * Copyright (c) 2007-2008 The Florida State University
4 * Copyright (c) 2009 The University of Edinburgh
5 * Copyright (c) 2012 ARM Limited
6 * Copyright (c) 2014-2015 Sven Karlsson
7 * All rights reserved.
8 *

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44 *
45 * Authors: Steve Reinhardt
46 * Alec Roelke
47 */
48#ifndef __ARCH_RISCV_LOCKED_MEM_HH__
49#define __ARCH_RISCV_LOCKED_MEM_HH__
50
51#include <stack>
52
53#include "arch/registers.hh"
54#include "base/logging.hh"
55#include "base/trace.hh"
56#include "debug/LLSC.hh"
57#include "mem/packet.hh"
58#include "mem/request.hh"
59
60/*
61 * ISA-specific helper functions for locked memory accesses.
62 */
63namespace RiscvISA
64{
65
66const int WARN_FAILURE = 10000;
67
68// RISC-V allows multiple locks per hart, but each SC has to unlock the most
69// recent one, so we use a stack here.
70extern std::stack<Addr> locked_addrs;
71
72template <class XC> inline void
73handleLockedSnoop(XC *xc, PacketPtr pkt, Addr cacheBlockMask)
74{
75 if (locked_addrs.empty())
76 return;
77 Addr snoop_addr = pkt->getAddr() & cacheBlockMask;
78 DPRINTF(LLSC, "Locked snoop on address %x.\n", snoop_addr);
79 if ((locked_addrs.top() & cacheBlockMask) == snoop_addr)
80 locked_addrs.pop();
81}
82
83
84template <class XC> inline void
85handleLockedRead(XC *xc, const RequestPtr &req)
86{
87 locked_addrs.push(req->getPaddr() & ~0xF);
88 DPRINTF(LLSC, "[cid:%d]: Reserved address %x.\n",
89 req->contextId(), req->getPaddr() & ~0xF);
90}
91
92template <class XC> inline void
93handleLockedSnoopHit(XC *xc)
94{}
95
96template <class XC> inline bool
97handleLockedWrite(XC *xc, const RequestPtr &req, Addr cacheBlockMask)
98{
99 // Normally RISC-V uses zero to indicate success and nonzero to indicate
100 // failure (right now only 1 is reserved), but in gem5 zero indicates
101 // failure and one indicates success, so here we conform to that (it should
102 // be switched in the instruction's implementation)
103
104 DPRINTF(LLSC, "[cid:%d]: locked_addrs empty? %s.\n", req->contextId(),
105 locked_addrs.empty() ? "yes" : "no");
106 if (!locked_addrs.empty()) {
107 DPRINTF(LLSC, "[cid:%d]: addr = %x.\n", req->contextId(),
108 req->getPaddr() & ~0xF);
109 DPRINTF(LLSC, "[cid:%d]: last locked addr = %x.\n", req->contextId(),
110 locked_addrs.top());
111 }
112 if (locked_addrs.empty()
113 || locked_addrs.top() != ((req->getPaddr() & ~0xF))) {
114 req->setExtraData(0);
115 int stCondFailures = xc->readStCondFailures();
116 xc->setStCondFailures(++stCondFailures);
117 if (stCondFailures % WARN_FAILURE == 0) {
118 warn("%i: context %d: %d consecutive SC failures.\n",
119 curTick(), xc->contextId(), stCondFailures);
120 }
121 return false;

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