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| 1 | jermar | 1 | /* |
| 2 | * Copyright (C) 2001-2004 Jakub Jermar |
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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 | |||
| 29 | #include <arch/types.h> |
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| 30 | #include <config.h> |
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| 31 | #include <func.h> |
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| 32 | #include <mm/frame.h> |
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| 33 | #include <mm/page.h> |
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| 34 | #include <arch/mm/page.h> |
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| 35 | #include <arch/interrupt.h> |
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| 36 | #include <arch/asm.h> |
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| 37 | #include <synch/spinlock.h> |
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| 38 | |||
| 39 | /* |
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| 40 | * Note. |
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| 41 | * This is the preliminary code for controlling paging mechanism on i386. It is |
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| 42 | * needed by other parts of the kernel for its ability to map virtual addresses |
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| 43 | * to physical. SMP code relies on this feature. Other than that, this code is |
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| 44 | * by no means meant to implement virtual memory in terms of swapping pages in |
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| 45 | * and out. |
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| 46 | */ |
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| 47 | |||
| 48 | __address bootstrap_dba; |
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| 49 | |||
| 50 | void page_arch_init(void) |
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| 51 | { |
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| 52 | __address dba; |
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| 53 | __u32 i; |
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| 54 | |||
| 55 | if (config.cpu_active == 1) { |
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| 56 | dba = frame_alloc(FRAME_KA | FRAME_PANIC); |
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| 57 | memsetb(dba, PAGE_SIZE, 0); |
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| 58 | cpu_write_dba(dba); |
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| 59 | |||
| 60 | bootstrap_dba = dba; |
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| 61 | |||
| 62 | /* |
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| 63 | * Identity mapping for all but 0th page. |
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| 64 | */ |
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| 65 | for (i = 1; i < frames; i++) |
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| 66 | map_page_to_frame(i * PAGE_SIZE, i * PAGE_SIZE, PAGE_CACHEABLE, 0); |
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| 67 | |||
| 68 | trap_register(14, page_fault); |
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| 69 | } |
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| 70 | else { |
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| 71 | |||
| 72 | /* |
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| 73 | * Application processors need to create their own view of the |
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| 74 | * virtual address space. Because of that, each AP copies |
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| 75 | * already-initialized paging information from the bootstrap |
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| 76 | * processor and adjusts it to fulfill its needs. |
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| 77 | */ |
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| 78 | |||
| 79 | dba = frame_alloc(FRAME_KA | FRAME_PANIC); |
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| 80 | memcopy(bootstrap_dba, dba, PAGE_SIZE); |
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| 81 | cpu_write_dba(dba); |
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| 82 | } |
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| 83 | |||
| 84 | paging_on(); |
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| 85 | } |
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| 86 | |||
| 87 | /* |
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| 88 | * Besides mapping pages to frames, this function also sets the present bit of |
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| 89 | * the page's specifier in both page directory and respective page table. If |
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| 90 | * the page table for this page has not been allocated so far, it will take |
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| 91 | * care of it and allocate the necessary frame. |
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| 92 | * |
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| 93 | * When the copy parameter is positive, map_page_to_frame will not overwrite |
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| 94 | * the current mapping. It will allocate a new frame and do the mapping on it |
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| 95 | * instead. |
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| 96 | * |
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| 97 | * PAGE_CACHEABLE flag: when set, it turns caches for that page on |
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| 98 | * PAGE_NOT_PRESENT flag: when set, it marks the page not present |
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| 99 | * PAGE_USER flag: when set, the page is accessible from userspace |
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| 100 | */ |
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| 101 | void map_page_to_frame(__address page, __address frame, int flags, int copy) |
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| 102 | { |
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| 103 | struct page_specifier *pd, *pt; |
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| 104 | __address dba, newpt; |
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| 105 | int pde, pte; |
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| 106 | |||
| 107 | dba = cpu_read_dba(); |
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| 108 | |||
| 109 | pde = page >> 22; /* page directory entry */ |
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| 110 | pte = (page >> 12) & 0x3ff; /* page table entry */ |
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| 111 | |||
| 112 | pd = (struct page_specifier *) dba; |
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| 113 | |||
| 114 | if (!pd[pde].present) { |
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| 115 | /* |
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| 116 | * There is currently no page table for this address. Allocate |
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| 117 | * frame for the page table and clean it. |
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| 118 | */ |
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| 119 | newpt = frame_alloc(FRAME_KA); |
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| 120 | pd[pde].frame_address = newpt >> 12; |
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| 121 | memsetb(newpt, PAGE_SIZE, 0); |
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| 122 | pd[pde].present = 1; |
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| 123 | pd[pde].uaccessible = 1; |
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| 124 | } |
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| 125 | if (copy) { |
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| 126 | newpt = frame_alloc(FRAME_KA); |
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| 127 | memcopy(pd[pde].frame_address << 12, newpt, PAGE_SIZE); |
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| 128 | pd[pde].frame_address = newpt >> 12; |
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| 129 | } |
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| 130 | pt = (struct page_specifier *) (pd[pde].frame_address << 12); |
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| 131 | |||
| 132 | pt[pte].frame_address = frame >> 12; |
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| 133 | pt[pte].present = !(flags & PAGE_NOT_PRESENT); |
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| 134 | pt[pte].page_cache_disable = !(flags & PAGE_CACHEABLE); |
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| 135 | pt[pte].uaccessible = (flags & PAGE_USER) != 0; |
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| 136 | pt[pte].writeable = (flags & PAGE_WRITE) != 0; |
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| 137 | |||
| 138 | tlb_invalidate(0); |
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| 139 | } |