kernel/generic/src/mm/backend_anon.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 kernel_generic_mm
  30  * @{
  31  */
  32
  33 /**
  34  * @file
  35  * @brief       Backend for anonymous memory address space areas.
  36  *
  37  */
  38
  39 #include <assert.h>
  40 #include <mm/as.h>
  41 #include <mm/page.h>
  42 #include <mm/reserve.h>
  43 #include <genarch/mm/page_pt.h>
  44 #include <genarch/mm/page_ht.h>
  45 #include <mm/frame.h>
  46 #include <mm/slab.h>
  47 #include <mm/km.h>
  48 #include <synch/mutex.h>
  49 #include <adt/list.h>
  50 #include <errno.h>
  51 #include <typedefs.h>
  52 #include <align.h>
  53 #include <memw.h>
  54 #include <arch.h>
  55
  56 static bool anon_create(as_area_t *);
  57 static bool anon_resize(as_area_t *, size_t);
  58 static void anon_share(as_area_t *);
  59 static void anon_destroy(as_area_t *);
  60
  61 static bool anon_is_resizable(as_area_t *);
  62 static bool anon_is_shareable(as_area_t *);
  63
  64 static int anon_page_fault(as_area_t *, uintptr_t, pf_access_t);
  65 static void anon_frame_free(as_area_t *, uintptr_t, uintptr_t);
  66
  67 mem_backend_t anon_backend = {
  68         .create = anon_create,
  69         .resize = anon_resize,
  70         .share = anon_share,
  71         .destroy = anon_destroy,
  72
  73         .is_resizable = anon_is_resizable,
  74         .is_shareable = anon_is_shareable,
  75
  76         .page_fault = anon_page_fault,
  77         .frame_free = anon_frame_free,
  78
  79         .create_shared_data = NULL,
  80         .destroy_shared_data = NULL
  81 };
  82
  83 bool anon_create(as_area_t *area)
  84 {
  85         if (area->flags & AS_AREA_LATE_RESERVE)
  86                 return true;
  87
  88         return reserve_try_alloc(area->pages);
  89 }
  90
  91 bool anon_resize(as_area_t *area, size_t new_pages)
  92 {
  93         if (area->flags & AS_AREA_LATE_RESERVE)
  94                 return true;
  95
  96         if (new_pages > area->pages)
  97                 return reserve_try_alloc(new_pages - area->pages);
  98         else if (new_pages < area->pages)
  99                 reserve_free(area->pages - new_pages);
 100
 101         return true;
 102 }
 103
 104 /** Share the anonymous address space area.
 105  *
 106  * Sharing of anonymous area is done by duplicating its entire mapping
 107  * to the pagemap. Page faults will primarily search for frames there.
 108  *
 109  * The address space and address space area must be already locked.
 110  *
 111  * @param area Address space area to be shared.
 112  */
 113 void anon_share(as_area_t *area)
 114 {
 115         assert(mutex_locked(&area->as->lock));
 116         assert(mutex_locked(&area->lock));
 117         assert(!(area->flags & AS_AREA_LATE_RESERVE));
 118
 119         /*
 120          * Copy used portions of the area to sh_info's page map.
 121          */
 122         mutex_lock(&area->sh_info->lock);
 123         used_space_ival_t *ival = used_space_first(&area->used_space);
 124         while (ival != NULL) {
 125                 uintptr_t base = ival->page;
 126                 size_t count = ival->count;
 127                 unsigned int j;
 128
 129                 for (j = 0; j < count; j++) {
 130                         pte_t pte;
 131                         bool found;
 132
 133                         page_table_lock(area->as, false);
 134                         found = page_mapping_find(area->as, base + P2SZ(j),
 135                             false, &pte);
 136
 137                         (void)found;
 138                         assert(found);
 139                         assert(PTE_VALID(&pte));
 140                         assert(PTE_PRESENT(&pte));
 141
 142                         as_pagemap_insert(&area->sh_info->pagemap,
 143                             (base + P2SZ(j)) - area->base, PTE_GET_FRAME(&pte));
 144                         page_table_unlock(area->as, false);
 145
 146                         pfn_t pfn = ADDR2PFN(PTE_GET_FRAME(&pte));
 147                         frame_reference_add(pfn);
 148                 }
 149
 150                 ival = used_space_next(ival);
 151         }
 152         mutex_unlock(&area->sh_info->lock);
 153 }
 154
 155 void anon_destroy(as_area_t *area)
 156 {
 157         if (area->flags & AS_AREA_LATE_RESERVE)
 158                 return;
 159
 160         reserve_free(area->pages);
 161 }
 162
 163 bool anon_is_resizable(as_area_t *area)
 164 {
 165         return true;
 166 }
 167
 168 bool anon_is_shareable(as_area_t *area)
 169 {
 170         return !(area->flags & AS_AREA_LATE_RESERVE);
 171 }
 172
 173 /** Service a page fault in the anonymous memory address space area.
 174  *
 175  * The address space area and page tables must be already locked.
 176  *
 177  * @param area Pointer to the address space area.
 178  * @param upage Faulting virtual page.
 179  * @param access Access mode that caused the fault (i.e. read/write/exec).
 180  *
 181  * @return AS_PF_FAULT on failure (i.e. page fault) or AS_PF_OK on success (i.e.
 182  *     serviced).
 183  */
 184 int anon_page_fault(as_area_t *area, uintptr_t upage, pf_access_t access)
 185 {
 186         uintptr_t kpage;
 187         uintptr_t frame;
 188
 189         assert(page_table_locked(AS));
 190         assert(mutex_locked(&area->lock));
 191         assert(IS_ALIGNED(upage, PAGE_SIZE));
 192
 193         if (!as_area_check_access(area, access))
 194                 return AS_PF_FAULT;
 195
 196         mutex_lock(&area->sh_info->lock);
 197         if (area->sh_info->shared) {
 198                 /*
 199                  * The area is shared, chances are that the mapping can be found
 200                  * in the pagemap of the address space area share info
 201                  * structure.
 202                  * In the case that the pagemap does not contain the respective
 203                  * mapping, a new frame is allocated and the mapping is created.
 204                  */
 205                 errno_t rc = as_pagemap_find(&area->sh_info->pagemap,
 206                     upage - area->base, &frame);
 207                 if (rc != EOK) {
 208                         /* Need to allocate the frame */
 209                         kpage = km_temporary_page_get(&frame,
 210                             FRAME_NO_RESERVE);
 211                         memsetb((void *) kpage, PAGE_SIZE, 0);
 212                         km_temporary_page_put(kpage);
 213
 214                         /*
 215                          * Insert the address of the newly allocated
 216                          * frame to the pagemap.
 217                          */
 218                         as_pagemap_insert(&area->sh_info->pagemap,
 219                             upage - area->base, frame);
 220                 }
 221                 frame_reference_add(ADDR2PFN(frame));
 222         } else {
 223
 224                 /*
 225                  * In general, there can be several reasons that
 226                  * can have caused this fault.
 227                  *
 228                  * - non-existent mapping: the area is an anonymous
 229                  *   area (e.g. heap or stack) and so far has not been
 230                  *   allocated a frame for the faulting page
 231                  *
 232                  * - non-present mapping: another possibility,
 233                  *   currently not implemented, would be frame
 234                  *   reuse; when this becomes a possibility,
 235                  *   do not forget to distinguish between
 236                  *   the different causes
 237                  */
 238
 239                 if (area->flags & AS_AREA_LATE_RESERVE) {
 240                         /*
 241                          * Reserve the memory for this page now.
 242                          */
 243                         if (!reserve_try_alloc(1)) {
 244                                 mutex_unlock(&area->sh_info->lock);
 245                                 return AS_PF_SILENT;
 246                         }
 247                 }
 248
 249                 kpage = km_temporary_page_get(&frame, FRAME_NO_RESERVE);
 250                 memsetb((void *) kpage, PAGE_SIZE, 0);
 251                 km_temporary_page_put(kpage);
 252         }
 253         mutex_unlock(&area->sh_info->lock);
 254
 255         /*
 256          * Map 'upage' to 'frame'.
 257          * Note that TLB shootdown is not attempted as only new information is
 258          * being inserted into page tables.
 259          */
 260         page_mapping_insert(AS, upage, frame, as_area_get_flags(area));
 261         if (!used_space_insert(&area->used_space, upage, 1))
 262                 panic("Cannot insert used space.");
 263
 264         return AS_PF_OK;
 265 }
 266
 267 /** Free a frame that is backed by the anonymous memory backend.
 268  *
 269  * The address space area and page tables must be already locked.
 270  *
 271  * @param area Ignored.
 272  * @param page Virtual address of the page corresponding to the frame.
 273  * @param frame Frame to be released.
 274  */
 275 void anon_frame_free(as_area_t *area, uintptr_t page, uintptr_t frame)
 276 {
 277         assert(page_table_locked(area->as));
 278         assert(mutex_locked(&area->lock));
 279
 280         if (area->flags & AS_AREA_LATE_RESERVE) {
 281                 /*
 282                  * In case of the late reserve areas, physical memory will not
 283                  * be unreserved when the area is destroyed so we need to use
 284                  * the normal unreserving frame_free().
 285                  */
 286                 frame_free(frame, 1);
 287         } else {
 288                 /*
 289                  * The reserve will be given back when the area is destroyed or
 290                  * resized, so use the frame_free_noreserve() which does not
 291                  * manipulate the reserve or it would be given back twice.
 292                  */
 293                 frame_free_noreserve(frame, 1);
 294         }
 295 }
 296
 297 /** @}
 298  */