gem5/src/mem/page_table.cc

/*
 * Copyright (c) 2003 The Regents of The University of Michigan
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are
 * met: redistributions of source code must retain the above copyright
 * notice, this list of conditions and the following disclaimer;
 * redistributions in binary form must reproduce the above copyright
 * notice, this list of conditions and the following disclaimer in the
 * documentation and/or other materials provided with the distribution;
 * neither the name of the copyright holders nor the names of its
 * contributors may be used to endorse or promote products derived from
 * this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 *
 * Authors: Steve Reinhardt
 *          Ron Dreslinski
 *          Ali Saidi
 */

/**
 * @file
 * Definitions of page table.
 */
#include <string>
#include <map>
#include <fstream>

#include "arch/faults.hh"
#include "base/bitfield.hh"
#include "base/intmath.hh"
#include "base/trace.hh"
#include "mem/page_table.hh"
#include "sim/process.hh"
#include "sim/sim_object.hh"
#include "sim/system.hh"

using namespace std;
using namespace TheISA;

PageTable::PageTable(Process *_process, Addr _pageSize)
    : pageSize(_pageSize), offsetMask(mask(floorLog2(_pageSize))),
      process(_process)
{
    assert(isPowerOf2(pageSize));
    pTableCache[0].vaddr = 0;
    pTableCache[1].vaddr = 0;
    pTableCache[2].vaddr = 0;
}

PageTable::~PageTable()
{
}

void
PageTable::allocate(Addr vaddr, int64_t size)
{
    // starting address must be page aligned
    assert(pageOffset(vaddr) == 0);

    DPRINTF(MMU, "Allocating Page: %#x-%#x\n", vaddr, vaddr+ size);

    for (; size > 0; size -= pageSize, vaddr += pageSize) {
        PTableItr iter = pTable.find(vaddr);

        if (iter != pTable.end()) {
            // already mapped
            fatal("PageTable::allocate: address 0x%x already mapped",
                    vaddr);
        }

        pTable[vaddr] = TheISA::TlbEntry(process->M5_pid, vaddr,
                process->system->new_page());
        updateCache(vaddr, pTable[vaddr]);
    }
}

bool
PageTable::lookup(Addr vaddr, TheISA::TlbEntry &entry)
{
    Addr page_addr = pageAlign(vaddr);

    if (pTableCache[0].vaddr == page_addr) {
        entry = pTableCache[0].entry;
        return true;
    }
    if (pTableCache[1].vaddr == page_addr) {
        entry = pTableCache[1].entry;
        return true;
    }
    if (pTableCache[2].vaddr == page_addr) {
        entry = pTableCache[2].entry;
        return true;
    }

    PTableItr iter = pTable.find(page_addr);

    if (iter == pTable.end()) {
        return false;
    }

    updateCache(page_addr, iter->second);
    entry = iter->second;
    return true;
}

bool
PageTable::translate(Addr vaddr, Addr &paddr)
{
    TheISA::TlbEntry entry;
    if (!lookup(vaddr, entry)) {
        DPRINTF(MMU, "Couldn't Translate: %#x\n", vaddr);
        return false;
    }
    paddr = pageOffset(vaddr) + entry.pageStart();
    DPRINTF(MMU, "Translating: %#x->%#x\n", vaddr, paddr);
    return true;
}

Fault
PageTable::translate(RequestPtr req)
{
    Addr paddr;
    assert(pageAlign(req->getVaddr() + req->getSize() - 1)
           == pageAlign(req->getVaddr()));
    if (!translate(req->getVaddr(), paddr)) {
        return Fault(new GenericPageTableFault(req->getVaddr()));
    }
    req->setPaddr(paddr);
    if ((paddr & (pageSize - 1)) + req->getSize() > pageSize) {
        panic("Request spans page boundaries!\n");
        return NoFault;
    }
    return NoFault;
}

void
PageTable::serialize(std::ostream &os)
{
    paramOut(os, "ptable.size", pTable.size());

    int count = 0;

    PTableItr iter = pTable.begin();
    PTableItr end = pTable.end();
    while (iter != end) {
        os << "\n[" << csprintf("%s.Entry%d", process->name(), count) << "]\n";

        paramOut(os, "vaddr", iter->first);
        iter->second.serialize(os);

        ++iter;
        ++count;
    }
    assert(count == pTable.size());
}

void
PageTable::unserialize(Checkpoint *cp, const std::string &section)
{
    int i = 0, count;
    paramIn(cp, section, "ptable.size", count);
    Addr vaddr;
    TheISA::TlbEntry *entry;

    pTable.clear();

    while(i < count) {
        paramIn(cp, csprintf("%s.Entry%d", process->name(), i), "vaddr", vaddr);
        entry = new TheISA::TlbEntry();
        entry->unserialize(cp, csprintf("%s.Entry%d", process->name(), i));
        pTable[vaddr] = *entry;
        ++i;
   }
}