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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.  
  45. static index_t hash(__native key[]);
  46. static bool compare(__native key[], count_t keys, link_t *item);
  47. static void remove_callback(link_t *item);
  48.  
  49. static void ht_mapping_insert(as_t *as, __address page, __address frame, int flags);
  50. static void ht_mapping_remove(as_t *as, __address page);
  51. static pte_t *ht_mapping_find(as_t *as, __address page);
  52.  
  53. /**
  54.  * This lock protects the page hash table.
  55.  */
  56. SPINLOCK_INITIALIZE(page_ht_lock);
  57.  
  58. /**
  59.  * Page hash table.
  60.  * The page hash table may be accessed only when page_ht_lock is held.
  61.  */
  62. hash_table_t page_ht;
  63.  
  64. /** Hash table operations for page hash table. */
  65. hash_table_operations_t ht_operations = {
  66.     .hash = hash,
  67.     .compare = compare,
  68.     .remove_callback = remove_callback
  69. };
  70.  
  71. /** Page mapping operations for page hash table architectures. */
  72. page_mapping_operations_t ht_mapping_operations = {
  73.     .mapping_insert = ht_mapping_insert,
  74.     .mapping_remove = ht_mapping_remove,
  75.     .mapping_find = ht_mapping_find
  76. };
  77.  
  78. /** Compute page hash table index.
  79.  *
  80.  * @param key Array of two keys (i.e. page and address space).
  81.  *
  82.  * @return Index into page hash table.
  83.  */
  84. index_t hash(__native key[])
  85. {
  86.     as_t *as = (as_t *) key[KEY_AS];
  87.     __address page = (__address) key[KEY_PAGE];
  88.     index_t index;
  89.    
  90.     /*
  91.      * Virtual page addresses have roughly the same probability
  92.      * of occurring. Least significant bits of VPN compose the
  93.      * hash index.
  94.      */
  95.     index = ((page >> PAGE_WIDTH) & (PAGE_HT_ENTRIES-1));
  96.    
  97.     /*
  98.      * Address space structures are likely to be allocated from
  99.      * similar addresses. Least significant bits compose the
  100.      * hash index.
  101.      */
  102.     index |= ((__native) as) & (PAGE_HT_ENTRIES-1);
  103.    
  104.     return index;
  105. }
  106.  
  107. /** Compare page hash table item with page and/or address space.
  108.  *
  109.  * @param key Array of one or two keys (i.e. page and/or address space).
  110.  * @param keys Number of keys passed.
  111.  * @param item Item to compare the keys with.
  112.  *
  113.  * @return true on match, false otherwise.
  114.  */
  115. bool compare(__native key[], count_t keys, link_t *item)
  116. {
  117.     pte_t *t;
  118.  
  119.     ASSERT(item);
  120.     ASSERT((keys > 0) && (keys <= PAGE_HT_KEYS));
  121.  
  122.     /*
  123.      * Convert item to PTE.
  124.      */
  125.     t = hash_table_get_instance(item, pte_t, link);
  126.  
  127.     if (keys == PAGE_HT_KEYS) {
  128.         return (key[KEY_AS] == (__address) t->as) && (key[KEY_PAGE] == t->page);
  129.     } else {
  130.         return (key[KEY_AS] == (__address) t->as);
  131.     }
  132. }
  133.  
  134. /** Callback on page hash table item removal.
  135.  *
  136.  * @param item Page hash table item being removed.
  137.  */
  138. void remove_callback(link_t *item)
  139. {
  140.     pte_t *t;
  141.  
  142.     ASSERT(item);
  143.  
  144.     /*
  145.      * Convert item to PTE.
  146.      */
  147.     t = hash_table_get_instance(item, pte_t, link);
  148.  
  149.     free(t);
  150. }
  151.  
  152. /** Map page to frame using page hash table.
  153.  *
  154.  * Map virtual address 'page' to physical address 'frame'
  155.  * using 'flags'.
  156.  *
  157.  * The address space must be locked and interruptsmust be disabled.
  158.  *
  159.  * @param as Address space to which page belongs.
  160.  * @param page Virtual address of the page to be mapped.
  161.  * @param frame Physical address of memory frame to which the mapping is done.
  162.  * @param flags Flags to be used for mapping.
  163.  */
  164. void ht_mapping_insert(as_t *as, __address page, __address frame, int flags)
  165. {
  166.     pte_t *t;
  167.     __native key[2] = { (__address) as, page };
  168.    
  169.     spinlock_lock(&page_ht_lock);
  170.  
  171.     if (!hash_table_find(&page_ht, key)) {
  172.         t = (pte_t *) malloc(sizeof(pte_t), FRAME_ATOMIC);
  173.         ASSERT(t != NULL);
  174.  
  175.         t->g = (flags & PAGE_GLOBAL) != 0;
  176.         t->x = (flags & PAGE_EXEC) != 0;
  177.         t->w = (flags & PAGE_WRITE) != 0;
  178.         t->k = !(flags & PAGE_USER);
  179.         t->c = (flags & PAGE_CACHEABLE) != 0;
  180.         t->p = !(flags & PAGE_NOT_PRESENT);
  181.  
  182.         t->as = as;
  183.         t->page = page;
  184.         t->frame = frame;
  185.  
  186.         hash_table_insert(&page_ht, key, &t->link);
  187.     }
  188.    
  189.     spinlock_unlock(&page_ht_lock);
  190. }
  191.  
  192. /** Remove mapping of page from page hash table.
  193.  *
  194.  * Remove any mapping of 'page' within address space 'as'.
  195.  * TLB shootdown should follow in order to make effects of
  196.  * this call visible.
  197.  *
  198.  * The address space must be locked and interrupts must be disabled.
  199.  *
  200.  * @param as Address space to wich page belongs.
  201.  * @param page Virtual address of the page to be demapped.
  202.  */
  203. void ht_mapping_remove(as_t *as, __address page)
  204. {
  205.     __native key[2] = { (__address) as, page };
  206.    
  207.     spinlock_lock(&page_ht_lock);
  208.  
  209.     /*
  210.      * Note that removed PTE's will be freed
  211.      * by remove_callback().
  212.      */
  213.     hash_table_remove(&page_ht, key, 2);
  214.  
  215.     spinlock_unlock(&page_ht_lock);
  216. }
  217.  
  218.  
  219. /** Find mapping for virtual page in page hash table.
  220.  *
  221.  * Find mapping for virtual page.
  222.  *
  223.  * The address space must be locked and interrupts must be disabled.
  224.  *
  225.  * @param as Address space to wich page belongs.
  226.  * @param page Virtual page.
  227.  *
  228.  * @return NULL if there is no such mapping; requested mapping otherwise.
  229.  */
  230. pte_t *ht_mapping_find(as_t *as, __address page)
  231. {
  232.     link_t *hlp;
  233.     pte_t *t = NULL;
  234.     __native key[2] = { (__address) as, page };
  235.    
  236.     spinlock_lock(&page_ht_lock);
  237.  
  238.     hlp = hash_table_find(&page_ht, key);
  239.     if (hlp)
  240.         t = hash_table_get_instance(hlp, pte_t, link);
  241.  
  242.     spinlock_unlock(&page_ht_lock);
  243.     return t;
  244. }
  245.