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  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. #include <genarch/mm/page_ht.h>
  30. #include <mm/page.h>
  31. #include <arch/mm/page.h>
  32. #include <mm/frame.h>
  33. #include <mm/slab.h>
  34. #include <mm/as.h>
  35. #include <arch/mm/asid.h>
  36. #include <arch/types.h>
  37. #include <typedefs.h>
  38. #include <arch/asm.h>
  39. #include <synch/spinlock.h>
  40. #include <arch.h>
  41. #include <debug.h>
  42. #include <memstr.h>
  43. #include <adt/hash_table.h>
  44. #include <align.h>
  45.  
  46. static index_t hash(__native key[]);
  47. static bool compare(__native key[], count_t keys, link_t *item);
  48. static void remove_callback(link_t *item);
  49.  
  50. static void ht_mapping_insert(as_t *as, __address page, __address frame, int flags);
  51. static void ht_mapping_remove(as_t *as, __address page);
  52. static pte_t *ht_mapping_find(as_t *as, __address page);
  53.  
  54. /**
  55.  * This lock protects the page hash table. It must be acquired
  56.  * after address space lock and after any address space area
  57.  * locks.
  58.  */
  59. SPINLOCK_INITIALIZE(page_ht_lock);
  60.  
  61. /**
  62.  * Page hash table.
  63.  * The page hash table may be accessed only when page_ht_lock is held.
  64.  */
  65. hash_table_t page_ht;
  66.  
  67. /** Hash table operations for page hash table. */
  68. hash_table_operations_t ht_operations = {
  69.     .hash = hash,
  70.     .compare = compare,
  71.     .remove_callback = remove_callback
  72. };
  73.  
  74. /** Page mapping operations for page hash table architectures. */
  75. page_mapping_operations_t ht_mapping_operations = {
  76.     .mapping_insert = ht_mapping_insert,
  77.     .mapping_remove = ht_mapping_remove,
  78.     .mapping_find = ht_mapping_find
  79. };
  80.  
  81. /** Compute page hash table index.
  82.  *
  83.  * @param key Array of two keys (i.e. page and address space).
  84.  *
  85.  * @return Index into page hash table.
  86.  */
  87. index_t hash(__native key[])
  88. {
  89.     as_t *as = (as_t *) key[KEY_AS];
  90.     __address page = (__address) key[KEY_PAGE];
  91.     index_t index;
  92.    
  93.     /*
  94.      * Virtual page addresses have roughly the same probability
  95.      * of occurring. Least significant bits of VPN compose the
  96.      * hash index.
  97.      */
  98.     index = ((page >> PAGE_WIDTH) & (PAGE_HT_ENTRIES-1));
  99.    
  100.     /*
  101.      * Address space structures are likely to be allocated from
  102.      * similar addresses. Least significant bits compose the
  103.      * hash index.
  104.      */
  105.     index |= ((__native) as) & (PAGE_HT_ENTRIES-1);
  106.    
  107.     return index;
  108. }
  109.  
  110. /** Compare page hash table item with page and/or address space.
  111.  *
  112.  * @param key Array of one or two keys (i.e. page and/or address space).
  113.  * @param keys Number of keys passed.
  114.  * @param item Item to compare the keys with.
  115.  *
  116.  * @return true on match, false otherwise.
  117.  */
  118. bool compare(__native key[], count_t keys, link_t *item)
  119. {
  120.     pte_t *t;
  121.  
  122.     ASSERT(item);
  123.     ASSERT((keys > 0) && (keys <= PAGE_HT_KEYS));
  124.  
  125.     /*
  126.      * Convert item to PTE.
  127.      */
  128.     t = hash_table_get_instance(item, pte_t, link);
  129.  
  130.     if (keys == PAGE_HT_KEYS) {
  131.         return (key[KEY_AS] == (__address) t->as) && (key[KEY_PAGE] == t->page);
  132.     } else {
  133.         return (key[KEY_AS] == (__address) t->as);
  134.     }
  135. }
  136.  
  137. /** Callback on page hash table item removal.
  138.  *
  139.  * @param item Page hash table item being removed.
  140.  */
  141. void remove_callback(link_t *item)
  142. {
  143.     pte_t *t;
  144.  
  145.     ASSERT(item);
  146.  
  147.     /*
  148.      * Convert item to PTE.
  149.      */
  150.     t = hash_table_get_instance(item, pte_t, link);
  151.  
  152.     free(t);
  153. }
  154.  
  155. /** Map page to frame using page hash table.
  156.  *
  157.  * Map virtual address @page to physical address @frame
  158.  * using @flags.
  159.  *
  160.  * The page table must be locked and interrupts must be disabled.
  161.  *
  162.  * @param as Address space to which @page belongs.
  163.  * @param page Virtual address of the page to be mapped.
  164.  * @param frame Physical address of memory frame to which the mapping is done.
  165.  * @param flags Flags to be used for mapping.
  166.  */
  167. void ht_mapping_insert(as_t *as, __address page, __address frame, int flags)
  168. {
  169.     pte_t *t;
  170.     __native key[2] = { (__address) as, page = ALIGN_DOWN(page, PAGE_SIZE) };
  171.    
  172.     if (!hash_table_find(&page_ht, key)) {
  173.         t = (pte_t *) malloc(sizeof(pte_t), FRAME_ATOMIC);
  174.         ASSERT(t != NULL);
  175.  
  176.         t->g = (flags & PAGE_GLOBAL) != 0;
  177.         t->x = (flags & PAGE_EXEC) != 0;
  178.         t->w = (flags & PAGE_WRITE) != 0;
  179.         t->k = !(flags & PAGE_USER);
  180.         t->c = (flags & PAGE_CACHEABLE) != 0;
  181.         t->p = !(flags & PAGE_NOT_PRESENT);
  182.  
  183.         t->as = as;
  184.         t->page = page;
  185.         t->frame = frame;
  186.  
  187.         hash_table_insert(&page_ht, key, &t->link);
  188.     }
  189. }
  190.  
  191. /** Remove mapping of page from page hash table.
  192.  *
  193.  * Remove any mapping of @page within address space @as.
  194.  * TLB shootdown should follow in order to make effects of
  195.  * this call visible.
  196.  *
  197.  * The page table must be locked and interrupts must be disabled.
  198.  *
  199.  * @param as Address space to wich page belongs.
  200.  * @param page Virtual address of the page to be demapped.
  201.  */
  202. void ht_mapping_remove(as_t *as, __address page)
  203. {
  204.     __native key[2] = { (__address) as, page = ALIGN_DOWN(page, PAGE_SIZE) };
  205.    
  206.     /*
  207.      * Note that removed PTE's will be freed
  208.      * by remove_callback().
  209.      */
  210.     hash_table_remove(&page_ht, key, 2);
  211. }
  212.  
  213.  
  214. /** Find mapping for virtual page in page hash table.
  215.  *
  216.  * Find mapping for virtual page.
  217.  *
  218.  * The page table must be locked and interrupts must be disabled.
  219.  *
  220.  * @param as Address space to wich @page belongs.
  221.  * @param page Virtual page.
  222.  *
  223.  * @return NULL if there is no such mapping; requested mapping otherwise.
  224.  */
  225. pte_t *ht_mapping_find(as_t *as, __address page)
  226. {
  227.     link_t *hlp;
  228.     pte_t *t = NULL;
  229.     __native key[2] = { (__address) as, page = ALIGN_DOWN(page, PAGE_SIZE) };
  230.    
  231.     hlp = hash_table_find(&page_ht, key);
  232.     if (hlp)
  233.         t = hash_table_get_instance(hlp, pte_t, link);
  234.  
  235.     return t;
  236. }
  237.