| 1 | /*
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| 2 | * Copyright (c) 2007 Pavel Jancik, Michal Kebrt
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| 3 | * All rights reserved.
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| 4 | *
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| 5 | * Redistribution and use in source and binary forms, with or without
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| 6 | * modification, are permitted provided that the following conditions
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| 7 | * are met:
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| 8 | *
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| 9 | * - Redistributions of source code must retain the above copyright
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| 10 | * notice, this list of conditions and the following disclaimer.
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| 11 | * - Redistributions in binary form must reproduce the above copyright
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| 12 | * notice, this list of conditions and the following disclaimer in the
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| 13 | * documentation and/or other materials provided with the distribution.
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| 14 | * - The name of the author may not be used to endorse or promote products
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| 15 | * derived from this software without specific prior written permission.
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| 16 | *
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| 17 | * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
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| 18 | * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
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| 19 | * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
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| 20 | * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
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| 21 | * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
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| 22 | * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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| 23 | * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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| 24 | * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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| 25 | * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
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| 26 | * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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| 27 | */
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| 28 |
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| 29 |
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| 30 | /** @addtogroup arm32boot
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| 31 | * @{
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| 32 | */
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| 33 | /** @file
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| 34 | * @brief Memory management used while booting the kernel.
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| 35 | */
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| 36 |
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| 37 |
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| 38 | #include "mm.h"
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| 39 |
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| 40 |
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| 41 | /** Initializes "section" page table entry.
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| 42 | *
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| 43 | * Will be readable/writable by kernel with no access from user mode.
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| 44 | * Will belong to domain 0. No cache or buffering is enabled.
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| 45 | *
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| 46 | * @param pte Section entry to initialize.
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| 47 | * @param frame First frame in the section (frame number).
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| 48 | *
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| 49 | * @note If frame is not 1MB aligned, first lower 1MB aligned frame will be used.
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| 50 | */
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| 51 | static void init_pte_level0_section(pte_level0_section_t* pte, unsigned int frame)
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| 52 | {
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| 53 | pte->descriptor_type = PTE_DESCRIPTOR_SECTION;
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| 54 | pte->bufferable = 0;
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| 55 | pte->cacheable = 0;
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| 56 | pte->impl_specific = 0;
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| 57 | pte->domain = 0;
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| 58 | pte->should_be_zero_1 = 0;
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| 59 | pte->access_permission = PTE_AP_USER_NO_KERNEL_RW;
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| 60 | pte->should_be_zero_2 = 0;
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| 61 | pte->section_base_addr = frame;
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| 62 | }
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| 63 |
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| 64 |
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| 65 | /** Initializes page table used while booting the kernel. */
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| 66 | static void init_page_table(void)
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| 67 | {
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| 68 | int i;
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| 69 | const unsigned int first_kernel_page = ADDR2PFN(PA2KA(0));
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| 70 |
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| 71 | // create 1:1 virtual-physical mapping (in lower 2GB)
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| 72 | for (i = 0; i < first_kernel_page; i++) {
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| 73 | init_pte_level0_section(&page_table[i], i);
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| 74 | }
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| 75 |
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| 76 | // create 1:1 virtual-physical mapping in kernel space (upper 2GB),
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| 77 | // physical addresses start from 0
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| 78 | for (i = first_kernel_page; i < PTL0_ENTRIES; i++) {
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| 79 | init_pte_level0_section(&page_table[i], i - first_kernel_page);
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| 80 | }
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| 81 | }
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| 82 |
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| 83 |
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| 84 | /** Starts the MMU - initializes page table and enables paging. */
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| 85 | void mmu_start() {
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| 86 | init_page_table();
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| 87 | set_ptl0_address(page_table);
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| 88 | enable_paging();
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| 89 | }
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| 90 |
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| 91 |
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| 92 | /** @}
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| 93 | */
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| 94 |
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