kernel/genarch/src/mm/page_pt.c

   1 /*
   2  * Copyright (c) 2006 Jakub Jermar
   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
   7  * are met:
   8  *
   9  * - Redistributions of source code must retain the above copyright
  10  *   notice, this list of conditions and the following disclaimer.
  11  * - Redistributions in binary form must reproduce the above copyright
  12  *   notice, this list of conditions and the following disclaimer in the
  13  *   documentation and/or other materials provided with the distribution.
  14  * - The name of the author may not be used to endorse or promote products
  15  *   derived from this software without specific prior written permission.
  16  *
  17  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
  18  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
  19  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
  20  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
  21  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
  22  * NOT 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 OF
  26  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  27  */
  28
  29 /** @addtogroup genarchmm
  30  * @{
  31  */
  32
  33 /**
  34  * @file
  35  * @brief       Virtual Address Translation for hierarchical 4-level page tables.
  36  */
  37
  38 #include <genarch/mm/page_pt.h>
  39 #include <mm/page.h>
  40 #include <mm/frame.h>
  41 #include <mm/as.h>
  42 #include <arch/mm/page.h>
  43 #include <arch/mm/as.h>
  44 #include <arch/types.h>
  45 #include <arch/asm.h>
  46 #include <memstr.h>
  47
  48 static void pt_mapping_insert(as_t *as, uintptr_t page, uintptr_t frame, int flags);
  49 static void pt_mapping_remove(as_t *as, uintptr_t page);
  50 static pte_t *pt_mapping_find(as_t *as, uintptr_t page);
  51
  52 page_mapping_operations_t pt_mapping_operations = {
  53         .mapping_insert = pt_mapping_insert,
  54         .mapping_remove = pt_mapping_remove,
  55         .mapping_find = pt_mapping_find
  56 };
  57
  58 /** Map page to frame using hierarchical page tables.
  59  *
  60  * Map virtual address page to physical address frame
  61  * using flags.
  62  *
  63  * The page table must be locked and interrupts must be disabled.
  64  *
  65  * @param as Address space to wich page belongs.
  66  * @param page Virtual address of the page to be mapped.
  67  * @param frame Physical address of memory frame to which the mapping is done.
  68  * @param flags Flags to be used for mapping.
  69  */
  70 void pt_mapping_insert(as_t *as, uintptr_t page, uintptr_t frame, int flags)
  71 {
  72         pte_t *ptl0, *ptl1, *ptl2, *ptl3;
  73         pte_t *newpt;
  74
  75         ptl0 = (pte_t *) PA2KA((uintptr_t) as->genarch.page_table);
  76
  77         if (GET_PTL1_FLAGS(ptl0, PTL0_INDEX(page)) & PAGE_NOT_PRESENT) {
  78                 newpt = (pte_t *)frame_alloc(ONE_FRAME, FRAME_KA);
  79                 memsetb((uintptr_t)newpt, PAGE_SIZE, 0);
  80                 SET_PTL1_ADDRESS(ptl0, PTL0_INDEX(page), KA2PA(newpt));
  81                 SET_PTL1_FLAGS(ptl0, PTL0_INDEX(page), PAGE_PRESENT | PAGE_USER | PAGE_EXEC | PAGE_CACHEABLE | PAGE_WRITE);
  82         }
  83
  84         ptl1 = (pte_t *) PA2KA(GET_PTL1_ADDRESS(ptl0, PTL0_INDEX(page)));
  85
  86         if (GET_PTL2_FLAGS(ptl1, PTL1_INDEX(page)) & PAGE_NOT_PRESENT) {
  87                 newpt = (pte_t *)frame_alloc(ONE_FRAME, FRAME_KA);
  88                 memsetb((uintptr_t)newpt, PAGE_SIZE, 0);
  89                 SET_PTL2_ADDRESS(ptl1, PTL1_INDEX(page), KA2PA(newpt));
  90                 SET_PTL2_FLAGS(ptl1, PTL1_INDEX(page), PAGE_PRESENT | PAGE_USER | PAGE_EXEC | PAGE_CACHEABLE | PAGE_WRITE);
  91         }
  92
  93         ptl2 = (pte_t *) PA2KA(GET_PTL2_ADDRESS(ptl1, PTL1_INDEX(page)));
  94
  95         if (GET_PTL3_FLAGS(ptl2, PTL2_INDEX(page)) & PAGE_NOT_PRESENT) {
  96                 newpt = (pte_t *)frame_alloc(ONE_FRAME, FRAME_KA);
  97                 memsetb((uintptr_t)newpt, PAGE_SIZE, 0);
  98                 SET_PTL3_ADDRESS(ptl2, PTL2_INDEX(page), KA2PA(newpt));
  99                 SET_PTL3_FLAGS(ptl2, PTL2_INDEX(page), PAGE_PRESENT | PAGE_USER | PAGE_EXEC | PAGE_CACHEABLE | PAGE_WRITE);
 100         }
 101
 102         ptl3 = (pte_t *) PA2KA(GET_PTL3_ADDRESS(ptl2, PTL2_INDEX(page)));
 103
 104         SET_FRAME_ADDRESS(ptl3, PTL3_INDEX(page), frame);
 105         SET_FRAME_FLAGS(ptl3, PTL3_INDEX(page), flags);
 106 }
 107
 108 /** Remove mapping of page from hierarchical page tables.
 109  *
 110  * Remove any mapping of page within address space as.
 111  * TLB shootdown should follow in order to make effects of
 112  * this call visible.
 113  *
 114  * Empty page tables except PTL0 are freed.
 115  *
 116  * The page table must be locked and interrupts must be disabled.
 117  *
 118  * @param as Address space to wich page belongs.
 119  * @param page Virtual address of the page to be demapped.
 120  */
 121 void pt_mapping_remove(as_t *as, uintptr_t page)
 122 {
 123         pte_t *ptl0, *ptl1, *ptl2, *ptl3;
 124         bool empty = true;
 125         int i;
 126
 127         /*
 128          * First, remove the mapping, if it exists.
 129          */
 130
 131         ptl0 = (pte_t *) PA2KA((uintptr_t) as->genarch.page_table);
 132
 133         if (GET_PTL1_FLAGS(ptl0, PTL0_INDEX(page)) & PAGE_NOT_PRESENT)
 134                 return;
 135
 136         ptl1 = (pte_t *) PA2KA(GET_PTL1_ADDRESS(ptl0, PTL0_INDEX(page)));
 137
 138         if (GET_PTL2_FLAGS(ptl1, PTL1_INDEX(page)) & PAGE_NOT_PRESENT)
 139                 return;
 140
 141         ptl2 = (pte_t *) PA2KA(GET_PTL2_ADDRESS(ptl1, PTL1_INDEX(page)));
 142
 143         if (GET_PTL3_FLAGS(ptl2, PTL2_INDEX(page)) & PAGE_NOT_PRESENT)
 144                 return;
 145
 146         ptl3 = (pte_t *) PA2KA(GET_PTL3_ADDRESS(ptl2, PTL2_INDEX(page)));
 147
 148         /* Destroy the mapping. Setting to PAGE_NOT_PRESENT is not sufficient. */
 149         memsetb((uintptr_t) &ptl3[PTL3_INDEX(page)], sizeof(pte_t), 0);
 150
 151         /*
 152          * Second, free all empty tables along the way from PTL3 down to PTL0.
 153          */
 154
 155         /* check PTL3 */
 156         for (i = 0; i < PTL3_ENTRIES; i++) {
 157                 if (PTE_VALID(&ptl3[i])) {
 158                         empty = false;
 159                         break;
 160                 }
 161         }
 162         if (empty) {
 163                 /*
 164                  * PTL3 is empty.
 165                  * Release the frame and remove PTL3 pointer from preceding table.
 166                  */
 167                 frame_free(KA2PA((uintptr_t) ptl3));
 168                 if (PTL2_ENTRIES)
 169                         memsetb((uintptr_t) &ptl2[PTL2_INDEX(page)], sizeof(pte_t), 0);
 170                 else if (PTL1_ENTRIES)
 171                         memsetb((uintptr_t) &ptl1[PTL1_INDEX(page)], sizeof(pte_t), 0);
 172                 else
 173                         memsetb((uintptr_t) &ptl0[PTL0_INDEX(page)], sizeof(pte_t), 0);
 174         } else {
 175                 /*
 176                  * PTL3 is not empty.
 177                  * Therefore, there must be a path from PTL0 to PTL3 and
 178                  * thus nothing to free in higher levels.
 179                  */
 180                 return;
 181         }
 182
 183         /* check PTL2, empty is still true */
 184         if (PTL2_ENTRIES) {
 185                 for (i = 0; i < PTL2_ENTRIES; i++) {
 186                         if (PTE_VALID(&ptl2[i])) {
 187                                 empty = false;
 188                                 break;
 189                         }
 190                 }
 191                 if (empty) {
 192                         /*
 193                          * PTL2 is empty.
 194                          * Release the frame and remove PTL2 pointer from preceding table.
 195                          */
 196                         frame_free(KA2PA((uintptr_t) ptl2));
 197                         if (PTL1_ENTRIES)
 198                                 memsetb((uintptr_t) &ptl1[PTL1_INDEX(page)], sizeof(pte_t), 0);
 199                         else
 200                                 memsetb((uintptr_t) &ptl0[PTL0_INDEX(page)], sizeof(pte_t), 0);
 201                 }
 202                 else {
 203                         /*
 204                          * PTL2 is not empty.
 205                          * Therefore, there must be a path from PTL0 to PTL2 and
 206                          * thus nothing to free in higher levels.
 207                          */
 208                         return;
 209                 }
 210         }
 211
 212         /* check PTL1, empty is still true */
 213         if (PTL1_ENTRIES) {
 214                 for (i = 0; i < PTL1_ENTRIES; i++) {
 215                         if (PTE_VALID(&ptl1[i])) {
 216                                 empty = false;
 217                                 break;
 218                         }
 219                 }
 220                 if (empty) {
 221                         /*
 222                          * PTL1 is empty.
 223                          * Release the frame and remove PTL1 pointer from preceding table.
 224                          */
 225                         frame_free(KA2PA((uintptr_t) ptl1));
 226                         memsetb((uintptr_t) &ptl0[PTL0_INDEX(page)], sizeof(pte_t), 0);
 227                 }
 228         }
 229
 230 }
 231
 232 /** Find mapping for virtual page in hierarchical page tables.
 233  *
 234  * Find mapping for virtual page.
 235  *
 236  * The page table must be locked and interrupts must be disabled.
 237  *
 238  * @param as Address space to which page belongs.
 239  * @param page Virtual page.
 240  *
 241  * @return NULL if there is no such mapping; entry from PTL3 describing the mapping otherwise.
 242  */
 243 pte_t *pt_mapping_find(as_t *as, uintptr_t page)
 244 {
 245         pte_t *ptl0, *ptl1, *ptl2, *ptl3;
 246
 247         ptl0 = (pte_t *) PA2KA((uintptr_t) as->genarch.page_table);
 248
 249         if (GET_PTL1_FLAGS(ptl0, PTL0_INDEX(page)) & PAGE_NOT_PRESENT)
 250                 return NULL;
 251
 252         ptl1 = (pte_t *) PA2KA(GET_PTL1_ADDRESS(ptl0, PTL0_INDEX(page)));
 253
 254         if (GET_PTL2_FLAGS(ptl1, PTL1_INDEX(page)) & PAGE_NOT_PRESENT)
 255                 return NULL;
 256
 257         ptl2 = (pte_t *) PA2KA(GET_PTL2_ADDRESS(ptl1, PTL1_INDEX(page)));
 258
 259         if (GET_PTL3_FLAGS(ptl2, PTL2_INDEX(page)) & PAGE_NOT_PRESENT)
 260                 return NULL;
 261
 262         ptl3 = (pte_t *) PA2KA(GET_PTL3_ADDRESS(ptl2, PTL2_INDEX(page)));
 263
 264         return &ptl3[PTL3_INDEX(page)];
 265 }
 266
 267 /** @}
 268  */