multi_level_page_table.hh revision 12446 
1/*
2 * Copyright (c) 2014 Advanced Micro Devices, Inc.
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: Alexandru Dutu
29 */
30
31/**
32 * @file
33 * Declaration of a multi-level page table.
34 */
35
36#ifndef __MEM_MULTI_LEVEL_PAGE_TABLE_HH__
37#define __MEM_MULTI_LEVEL_PAGE_TABLE_HH__
38
39#include <string>
40
41#include "base/types.hh"
42#include "config/the_isa.hh"
43#include "mem/page_table.hh"
44
45class System;
46
47/**
48 * This class implements an in-memory multi-level page table that can be
49 * configured to follow ISA specifications. It can be used instead of the
50 * PageTable class in SE mode to allow CPU models (e.g. X86KvmCPU)
51 * to do a normal page table walk.
52 *
53 * To reduce memory required to store the page table, a multi-level page
54 * table stores its translations similarly with a radix tree. Let n be
55 * the number of levels and {Ln, Ln-1, ..., L1, L0} a set that specifies
56 * the number of entries for each level as base 2 logarithm values. A
57 * multi-level page table will store its translations at level 0 (the
58 * leaves of the tree) and it will be layed out in memory in the
59 * following way:
60 *
61 *                              +------------------------------+
62 * level n                      |Ln-1_E0|Ln-1_E1|...|Ln-1_E2^Ln|
63 *                              +------------------------------+
64 *                                 /       \
65 *            +------------------------+   +------------------------+
66 * level n-1  |Ln-2_E0|...|Ln-2_E2^Ln-1|   |Ln-2_E0|...|Ln-2_E2^Ln-1|
67 *            +------------------------+   +------------------------+
68 *                /            \             /              \
69 *                                  .
70 *                                  .
71 *                                  .
72 *               /                      /               \
73 *          +------------------+   +------------+     +------------+
74 * level 1  |L0_E1|...|L0_E2^L1|   |...|L0_E2^L1| ... |...|L0_E2^L1|
75 *          +------------------+   +------------+     +------------+
76 * , where
77 * +------------------------------+
78 * |Lk-1_E0|Lk-1_E1|...|Lk-1_E2^Lk|
79 * +------------------------------+
80 * is a level k entry that holds 2^Lk entries in Lk-1 level.
81 *
82 * Essentially, a level n entry will contain 2^Ln level n-1 entries,
83 * a level n-1 entry will hold 2^Ln-1 level n-2 entries etc.
84 *
85 * The virtual address is split into offsets that index into the
86 * different levels of the page table.
87 *
88 * +--------------------------------+
89 * |LnOffset|...|L1Offset|PageOffset|
90 * +--------------------------------+
91 *
92 * For example L0Offset will be formed by the bits in range
93 * [log2(PageOffset), log2(PageOffset)+L0].
94 *
95 * For every level of the page table, from n to 1, the base address
96 * of the entry is loaded, the offset in the virtual address for
97 * that particular level is used to index into the entry which
98 * will reveal the memory address of the entry in the next level.
99 *
100 * @see MultiLevelPageTable
101 */
102template <class ISAOps>
103class MultiLevelPageTable : public FuncPageTable
104{
105    /**
106     * ISA specific operations
107     */
108    ISAOps pTableISAOps;
109
110    /**
111     * Pointer to System object
112     */
113    System *system;
114
115    /**
116     * Physical address to the last level of the page table
117     */
118    Addr basePtr;
119
120    /**
121     * Vector with sizes of all levels in base 2 logarithmic
122     */
123    const std::vector<uint8_t> logLevelSize;
124
125    /**
126     * Number of levels contained by the page table
127     */
128    const uint64_t numLevels;
129
130    /**
131     * Method for walking the page table
132     *
133     * @param vaddr Virtual address that is being looked-up
134     * @param allocate Specifies whether memory should be allocated while
135     *                  walking the page table
136     * @return PTE_addr The address of the found PTE
137     */
138    void walk(Addr vaddr, bool allocate, Addr &PTE_addr);
139
140public:
141    MultiLevelPageTable(const std::string &__name, uint64_t _pid,
142                        System *_sys, Addr pageSize);
143    ~MultiLevelPageTable();
144
145    void initState(ThreadContext* tc) override;
146
147    void map(Addr vaddr, Addr paddr, int64_t size,
148             uint64_t flags = 0) override;
149    void remap(Addr vaddr, int64_t size, Addr new_vaddr) override;
150    void unmap(Addr vaddr, int64_t size) override;
151    void serialize(CheckpointOut &cp) const override;
152    void unserialize(CheckpointIn &cp) override;
153};
154#endif // __MEM_MULTI_LEVEL_PAGE_TABLE_HH__
155