multi_level_page_table.hh revision 11175 
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 "arch/isa_traits.hh"
42#include "arch/tlb.hh"
43#include "base/types.hh"
44#include "config/the_isa.hh"
45#include "mem/page_table.hh"
46#include "sim/serialize.hh"
47#include "sim/system.hh"
48
49/**
50 * This class implements an in-memory multi-level page table that can be
51 * configured to follow ISA specifications. It can be used instead of the
52 * PageTable class in SE mode to allow CPU models (e.g. X86KvmCPU)
53 * to do a normal page table walk.
54 *
55 * To reduce memory required to store the page table, a multi-level page
56 * table stores its translations similarly with a radix tree. Let n be
57 * the number of levels and {Ln, Ln-1, ..., L1, L0} a set that specifies
58 * the number of entries for each level as base 2 logarithm values. A
59 * multi-level page table will store its translations at level 0 (the
60 * leaves of the tree) and it will be layed out in memory in the
61 * following way:
62 *
63 *                              +------------------------------+
64 * level n                      |Ln-1_E0|Ln-1_E1|...|Ln-1_E2^Ln|
65 *                              +------------------------------+
66 *                                 /       \
67 *            +------------------------+   +------------------------+
68 * level n-1  |Ln-2_E0|...|Ln-2_E2^Ln-1|   |Ln-2_E0|...|Ln-2_E2^Ln-1|
69 *            +------------------------+   +------------------------+
70 *                /            \             /              \
71 *                                  .
72 *                                  .
73 *                                  .
74 *               /                      /               \
75 *          +------------------+   +------------+     +------------+
76 * level 1  |L0_E1|...|L0_E2^L1|   |...|L0_E2^L1| ... |...|L0_E2^L1|
77 *          +------------------+   +------------+     +------------+
78 * , where
79 * +------------------------------+
80 * |Lk-1_E0|Lk-1_E1|...|Lk-1_E2^Lk|
81 * +------------------------------+
82 * is a level k entry that holds 2^Lk entries in Lk-1 level.
83 *
84 * Essentially, a level n entry will contain 2^Ln level n-1 entries,
85 * a level n-1 entry will hold 2^Ln-1 level n-2 entries etc.
86 *
87 * The virtual address is split into offsets that index into the
88 * different levels of the page table.
89 *
90 * +--------------------------------+
91 * |LnOffset|...|L1Offset|PageOffset|
92 * +--------------------------------+
93 *
94 * For example L0Offset will be formed by the bits in range
95 * [log2(PageOffset), log2(PageOffset)+L0].
96 *
97 * For every level of the page table, from n to 1, the base address
98 * of the entry is loaded, the offset in the virtual address for
99 * that particular level is used to index into the entry which
100 * will reveal the memory address of the entry in the next level.
101 *
102 * @see MultiLevelPageTable
103 */
104template <class ISAOps>
105class MultiLevelPageTable : public PageTableBase
106{
107    /**
108     * ISA specific operations
109     */
110    ISAOps pTableISAOps;
111
112    /**
113     * Pointer to System object
114     */
115    System *system;
116
117    /**
118     * Physical address to the last level of the page table
119     */
120    Addr basePtr;
121
122    /**
123     * Vector with sizes of all levels in base 2 logarithmic
124     */
125    const std::vector<uint8_t> logLevelSize;
126
127    /**
128     * Number of levels contained by the page table
129     */
130    const uint64_t numLevels;
131
132    /**
133     * Method for walking the page table
134     *
135     * @param vaddr Virtual address that is being looked-up
136     * @param allocate Specifies whether memory should be allocated while
137     *                  walking the page table
138     * @return PTE_addr The address of the found PTE
139     * @retval true if the page table walk has succeded, false otherwhise
140     */
141    bool walk(Addr vaddr, bool allocate, Addr &PTE_addr);
142
143public:
144    MultiLevelPageTable(const std::string &__name, uint64_t _pid,
145                        System *_sys);
146    ~MultiLevelPageTable();
147
148    void initState(ThreadContext* tc) override;
149
150    void map(Addr vaddr, Addr paddr, int64_t size,
151             uint64_t flags = 0) override;
152    void remap(Addr vaddr, int64_t size, Addr new_vaddr) override;
153    void unmap(Addr vaddr, int64_t size) override;
154    bool isUnmapped(Addr vaddr, int64_t size) override;
155    bool lookup(Addr vaddr, TheISA::TlbEntry &entry) override;
156    void serialize(CheckpointOut &cp) const override;
157    void unserialize(CheckpointIn &cp) override;
158};
159#endif // __MEM_MULTI_LEVEL_PAGE_TABLE_HH__
160