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/*
* Copyright (c) 2014 Advanced Micro Devices, Inc.
* 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: Alexandru Dutu
*/
/**
* @file
* Declaration of a multi-level page table.
*/
#ifndef __MEM_MULTI_LEVEL_PAGE_TABLE_HH__
#define __MEM_MULTI_LEVEL_PAGE_TABLE_HH__
#include <string>
#include "base/types.hh"
#include "config/the_isa.hh"
#include "mem/page_table.hh"
class System;
/**
* This class implements an in-memory multi-level page table that can be
* configured to follow ISA specifications. It can be used instead of the
* PageTable class in SE mode to allow CPU models (e.g. X86KvmCPU)
* to do a normal page table walk.
*
* To reduce memory required to store the page table, a multi-level page
* table stores its translations similarly with a radix tree. Let n be
* the number of levels and {Ln, Ln-1, ..., L1, L0} a set that specifies
* the number of entries for each level as base 2 logarithm values. A
* multi-level page table will store its translations at level 0 (the
* leaves of the tree) and it will be layed out in memory in the
* following way:
*
* +------------------------------+
* level n |Ln-1_E0|Ln-1_E1|...|Ln-1_E2^Ln|
* +------------------------------+
* / \
* +------------------------+ +------------------------+
* level n-1 |Ln-2_E0|...|Ln-2_E2^Ln-1| |Ln-2_E0|...|Ln-2_E2^Ln-1|
* +------------------------+ +------------------------+
* / \ / \
* .
* .
* .
* / / \
* +------------------+ +------------+ +------------+
* level 1 |L0_E1|...|L0_E2^L1| |...|L0_E2^L1| ... |...|L0_E2^L1|
* +------------------+ +------------+ +------------+
* , where
* +------------------------------+
* |Lk-1_E0|Lk-1_E1|...|Lk-1_E2^Lk|
* +------------------------------+
* is a level k entry that holds 2^Lk entries in Lk-1 level.
*
* Essentially, a level n entry will contain 2^Ln level n-1 entries,
* a level n-1 entry will hold 2^Ln-1 level n-2 entries etc.
*
* The virtual address is split into offsets that index into the
* different levels of the page table.
*
* +--------------------------------+
* |LnOffset|...|L1Offset|PageOffset|
* +--------------------------------+
*
* For example L0Offset will be formed by the bits in range
* [log2(PageOffset), log2(PageOffset)+L0].
*
* For every level of the page table, from n to 1, the base address
* of the entry is loaded, the offset in the virtual address for
* that particular level is used to index into the entry which
* will reveal the memory address of the entry in the next level.
*
* @see MultiLevelPageTable
*/
template <class ISAOps>
class MultiLevelPageTable : public PageTableBase
{
/**
* ISA specific operations
*/
ISAOps pTableISAOps;
/**
* Pointer to System object
*/
System *system;
/**
* Physical address to the last level of the page table
*/
Addr basePtr;
/**
* Vector with sizes of all levels in base 2 logarithmic
*/
const std::vector<uint8_t> logLevelSize;
/**
* Number of levels contained by the page table
*/
const uint64_t numLevels;
/**
* Method for walking the page table
*
* @param vaddr Virtual address that is being looked-up
* @param allocate Specifies whether memory should be allocated while
* walking the page table
* @return PTE_addr The address of the found PTE
* @retval true if the page table walk has succeded, false otherwhise
*/
bool walk(Addr vaddr, bool allocate, Addr &PTE_addr);
public:
MultiLevelPageTable(const std::string &__name, uint64_t _pid,
System *_sys, Addr pageSize);
~MultiLevelPageTable();
void initState(ThreadContext* tc) override;
void map(Addr vaddr, Addr paddr, int64_t size,
uint64_t flags = 0) override;
void remap(Addr vaddr, int64_t size, Addr new_vaddr) override;
void unmap(Addr vaddr, int64_t size) override;
bool isUnmapped(Addr vaddr, int64_t size) override;
bool lookup(Addr vaddr, TheISA::TlbEntry &entry) override;
void serialize(CheckpointOut &cp) const override;
void unserialize(CheckpointIn &cp) override;
};
#endif // __MEM_MULTI_LEVEL_PAGE_TABLE_HH__
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