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 <adt/btree.h>
  51 #include <errno.h>
  52 #include <typedefs.h>
  53 #include <align.h>
  54 #include <mem.h>
  55 #include <arch.h>
  56
  57 static bool anon_create(as_area_t *);
  58 static bool anon_resize(as_area_t *, size_t);
  59 static void anon_share(as_area_t *);
  60 static void anon_destroy(as_area_t *);
  61
  62 static bool anon_is_resizable(as_area_t *);
  63 static bool anon_is_shareable(as_area_t *);
  64
  65 static int anon_page_fault(as_area_t *, uintptr_t, pf_access_t);
  66 static void anon_frame_free(as_area_t *, uintptr_t, uintptr_t);
  67
  68 mem_backend_t anon_backend = {
  69         .create = anon_create,
  70         .resize = anon_resize,
  71         .share = anon_share,
  72         .destroy = anon_destroy,
  73
  74         .is_resizable = anon_is_resizable,
  75         .is_shareable = anon_is_shareable,
  76
  77         .page_fault = anon_page_fault,
  78         .frame_free = anon_frame_free,
  79
  80         .create_shared_data = NULL,
  81         .destroy_shared_data = NULL
  82 };
  83
  84 bool anon_create(as_area_t *area)
  85 {
  86         if (area->flags & AS_AREA_LATE_RESERVE)
  87                 return true;
  88
  89         return reserve_try_alloc(area->pages);
  90 }
  91
  92 bool anon_resize(as_area_t *area, size_t new_pages)
  93 {
  94         if (area->flags & AS_AREA_LATE_RESERVE)
  95                 return true;
  96
  97         if (new_pages > area->pages)
  98                 return reserve_try_alloc(new_pages - area->pages);
  99         else if (new_pages < area->pages)
 100                 reserve_free(area->pages - new_pages);
 101
 102         return true;
 103 }
 104
 105 /** Share the anonymous address space area.
 106  *
 107  * Sharing of anonymous area is done by duplicating its entire mapping
 108  * to the pagemap. Page faults will primarily search for frames there.
 109  *
 110  * The address space and address space area must be already locked.
 111  *
 112  * @param area Address space area to be shared.
 113  */
 114 void anon_share(as_area_t *area)
 115 {
 116         assert(mutex_locked(&area->as->lock));
 117         assert(mutex_locked(&area->lock));
 118         assert(!(area->flags & AS_AREA_LATE_RESERVE));
 119
 120         /*
 121          * Copy used portions of the area to sh_info's page map.
 122          */
 123         mutex_lock(&area->sh_info->lock);
 124         list_foreach(area->used_space.leaf_list, leaf_link, btree_node_t,
 125             node) {
 126                 unsigned int i;
 127
 128                 for (i = 0; i < node->keys; i++) {
 129                         uintptr_t base = node->key[i];
 130                         size_t count = (size_t) node->value[i];
 131                         unsigned int j;
 132
 133                         for (j = 0; j < count; j++) {
 134                                 pte_t pte;
 135                                 bool found;
 136
 137                                 page_table_lock(area->as, false);
 138                                 found = page_mapping_find(area->as,
 139                                     base + P2SZ(j), false, &pte);
 140
 141                                 (void)found;
 142                                 assert(found);
 143                                 assert(PTE_VALID(&pte));
 144                                 assert(PTE_PRESENT(&pte));
 145
 146                                 as_pagemap_insert(&area->sh_info->pagemap,
 147                                     (base + P2SZ(j)) - area->base,
 148                                     PTE_GET_FRAME(&pte));
 149                                 page_table_unlock(area->as, false);
 150
 151                                 pfn_t pfn = ADDR2PFN(PTE_GET_FRAME(&pte));
 152                                 frame_reference_add(pfn);
 153                         }
 154
 155                 }
 156         }
 157         mutex_unlock(&area->sh_info->lock);
 158 }
 159
 160 void anon_destroy(as_area_t *area)
 161 {
 162         if (area->flags & AS_AREA_LATE_RESERVE)
 163                 return;
 164
 165         reserve_free(area->pages);
 166 }
 167
 168 bool anon_is_resizable(as_area_t *area)
 169 {
 170         return true;
 171 }
 172
 173 bool anon_is_shareable(as_area_t *area)
 174 {
 175         return !(area->flags & AS_AREA_LATE_RESERVE);
 176 }
 177
 178 /** Service a page fault in the anonymous memory address space area.
 179  *
 180  * The address space area and page tables must be already locked.
 181  *
 182  * @param area Pointer to the address space area.
 183  * @param upage Faulting virtual page.
 184  * @param access Access mode that caused the fault (i.e. read/write/exec).
 185  *
 186  * @return AS_PF_FAULT on failure (i.e. page fault) or AS_PF_OK on success (i.e.
 187  *     serviced).
 188  */
 189 int anon_page_fault(as_area_t *area, uintptr_t upage, pf_access_t access)
 190 {
 191         uintptr_t kpage;
 192         uintptr_t frame;
 193
 194         assert(page_table_locked(AS));
 195         assert(mutex_locked(&area->lock));
 196         assert(IS_ALIGNED(upage, PAGE_SIZE));
 197
 198         if (!as_area_check_access(area, access))
 199                 return AS_PF_FAULT;
 200
 201         mutex_lock(&area->sh_info->lock);
 202         if (area->sh_info->shared) {
 203                 /*
 204                  * The area is shared, chances are that the mapping can be found
 205                  * in the pagemap of the address space area share info
 206                  * structure.
 207                  * In the case that the pagemap does not contain the respective
 208                  * mapping, a new frame is allocated and the mapping is created.
 209                  */
 210                 errno_t rc = as_pagemap_find(&area->sh_info->pagemap,
 211                     upage - area->base, &frame);
 212                 if (rc != EOK) {
 213                         /* Need to allocate the frame */
 214                         kpage = km_temporary_page_get(&frame,
 215                             FRAME_NO_RESERVE);
 216                         memsetb((void *) kpage, PAGE_SIZE, 0);
 217                         km_temporary_page_put(kpage);
 218
 219                         /*
 220                          * Insert the address of the newly allocated
 221                          * frame to the pagemap.
 222                          */
 223                         as_pagemap_insert(&area->sh_info->pagemap,
 224                             upage - area->base, frame);
 225                 }
 226                 frame_reference_add(ADDR2PFN(frame));
 227         } else {
 228
 229                 /*
 230                  * In general, there can be several reasons that
 231                  * can have caused this fault.
 232                  *
 233                  * - non-existent mapping: the area is an anonymous
 234                  *   area (e.g. heap or stack) and so far has not been
 235                  *   allocated a frame for the faulting page
 236                  *
 237                  * - non-present mapping: another possibility,
 238                  *   currently not implemented, would be frame
 239                  *   reuse; when this becomes a possibility,
 240                  *   do not forget to distinguish between
 241                  *   the different causes
 242                  */
 243
 244                 if (area->flags & AS_AREA_LATE_RESERVE) {
 245                         /*
 246                          * Reserve the memory for this page now.
 247                          */
 248                         if (!reserve_try_alloc(1)) {
 249                                 mutex_unlock(&area->sh_info->lock);
 250                                 return AS_PF_SILENT;
 251                         }
 252                 }
 253
 254                 kpage = km_temporary_page_get(&frame, FRAME_NO_RESERVE);
 255                 memsetb((void *) kpage, PAGE_SIZE, 0);
 256                 km_temporary_page_put(kpage);
 257         }
 258         mutex_unlock(&area->sh_info->lock);
 259
 260         /*
 261          * Map 'upage' to 'frame'.
 262          * Note that TLB shootdown is not attempted as only new information is
 263          * being inserted into page tables.
 264          */
 265         page_mapping_insert(AS, upage, frame, as_area_get_flags(area));
 266         if (!used_space_insert(area, upage, 1))
 267                 panic("Cannot insert used space.");
 268
 269         return AS_PF_OK;
 270 }
 271
 272 /** Free a frame that is backed by the anonymous memory backend.
 273  *
 274  * The address space area and page tables must be already locked.
 275  *
 276  * @param area Ignored.
 277  * @param page Virtual address of the page corresponding to the frame.
 278  * @param frame Frame to be released.
 279  */
 280 void anon_frame_free(as_area_t *area, uintptr_t page, uintptr_t frame)
 281 {
 282         assert(page_table_locked(area->as));
 283         assert(mutex_locked(&area->lock));
 284
 285         if (area->flags & AS_AREA_LATE_RESERVE) {
 286                 /*
 287                  * In case of the late reserve areas, physical memory will not
 288                  * be unreserved when the area is destroyed so we need to use
 289                  * the normal unreserving frame_free().
 290                  */
 291                 frame_free(frame, 1);
 292         } else {
 293                 /*
 294                  * The reserve will be given back when the area is destroyed or
 295                  * resized, so use the frame_free_noreserve() which does not
 296                  * manipulate the reserve or it would be given back twice.
 297                  */
 298                 frame_free_noreserve(frame, 1);
 299         }
 300 }
 301
 302 /** @}
 303  */