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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 pte_t *ht_mapping_find(as_t *as, __address page);
  51.  
  52. /**
  53.  * This lock protects the page hash table.
  54.  */
  55. SPINLOCK_INITIALIZE(page_ht_lock);
  56.  
  57. /**
  58.  * Page hash table.
  59.  * The page hash table may be accessed only when page_ht_lock is held.
  60.  */
  61. hash_table_t page_ht;
  62.  
  63. /** Hash table operations for page hash table. */
  64. hash_table_operations_t ht_operations = {
  65.     .hash = hash,
  66.     .compare = compare,
  67.     .remove_callback = remove_callback
  68. };
  69.  
  70. /** Page mapping operations for page hash table architectures. */
  71. page_mapping_operations_t ht_mapping_operations = {
  72.     .mapping_insert = ht_mapping_insert,
  73.     .mapping_find = ht_mapping_find
  74. };
  75.  
  76. /** Compute page hash table index.
  77.  *
  78.  * @param key Array of two keys (i.e. page and address space).
  79.  *
  80.  * @return Index into page hash table.
  81.  */
  82. index_t hash(__native key[])
  83. {
  84.     as_t *as = (as_t *) key[KEY_AS];
  85.     __address page = (__address) key[KEY_PAGE];
  86.     index_t index;
  87.    
  88.     /*
  89.      * Virtual page addresses have roughly the same probability
  90.      * of occurring. Least significant bits of VPN compose the
  91.      * hash index.
  92.      */
  93.     index = ((page >> PAGE_WIDTH) & (PAGE_HT_ENTRIES-1));
  94.    
  95.     /*
  96.      * Address space structures are likely to be allocated from
  97.      * similar addresses. Least significant bits compose the
  98.      * hash index.
  99.      */
  100.     index |= ((__native) as) & (PAGE_HT_ENTRIES-1);
  101.    
  102.     return index;
  103. }
  104.  
  105. /** Compare page hash table item with page and/or address space.
  106.  *
  107.  * @param key Array of one or two keys (i.e. page and/or address space).
  108.  * @param keys Number of keys passed.
  109.  * @param item Item to compare the keys with.
  110.  *
  111.  * @return true on match, false otherwise.
  112.  */
  113. bool compare(__native key[], count_t keys, link_t *item)
  114. {
  115.     pte_t *t;
  116.  
  117.     ASSERT(item);
  118.     ASSERT((keys > 0) && (keys <= PAGE_HT_KEYS));
  119.  
  120.     /*
  121.      * Convert item to PTE.
  122.      */
  123.     t = hash_table_get_instance(item, pte_t, link);
  124.  
  125.     if (keys == PAGE_HT_KEYS) {
  126.         return (key[KEY_AS] == (__address) t->as) && (key[KEY_PAGE] == t->page);
  127.     } else {
  128.         return (key[KEY_AS] == (__address) t->as);
  129.     }
  130. }
  131.  
  132. /** Callback on page hash table item removal.
  133.  *
  134.  * @param item Page hash table item being removed.
  135.  */
  136. void remove_callback(link_t *item)
  137. {
  138.     pte_t *t;
  139.  
  140.     ASSERT(item);
  141.  
  142.     /*
  143.      * Convert item to PTE.
  144.      */
  145.     t = hash_table_get_instance(item, pte_t, link);
  146.  
  147.     free(t);
  148. }
  149.  
  150. /** Map page to frame using page hash table.
  151.  *
  152.  * Map virtual address 'page' to physical address 'frame'
  153.  * using 'flags'.
  154.  *
  155.  * The address space must be locked and interruptsmust be disabled.
  156.  *
  157.  * @param as Address space to which page belongs.
  158.  * @param page Virtual address of the page to be mapped.
  159.  * @param frame Physical address of memory frame to which the mapping is done.
  160.  * @param flags Flags to be used for mapping.
  161.  */
  162. void ht_mapping_insert(as_t *as, __address page, __address frame, int flags)
  163. {
  164.     pte_t *t;
  165.     ipl_t ipl;
  166.     __native key[2] = { (__address) as, page };
  167.    
  168.     ipl = interrupts_disable();
  169.     spinlock_lock(&page_ht_lock);
  170.  
  171.     if (!hash_table_find(&page_ht, key)) {
  172.         t = (pte_t *) malloc(sizeof(pte_t));
  173.         ASSERT(t != NULL);
  174.    
  175.         hash_table_insert(&page_ht, key, &t->link);
  176.     }
  177.    
  178.     spinlock_unlock(&page_ht_lock);
  179.     interrupts_restore(ipl);
  180. }
  181.  
  182. /** Find mapping for virtual page in page hash table.
  183.  *
  184.  * Find mapping for virtual page.
  185.  *
  186.  * The address space must be locked and interrupts must be disabled.
  187.  *
  188.  * @param as Address space to wich page belongs.
  189.  * @param page Virtual page.
  190.  *
  191.  * @return NULL if there is no such mapping; requested mapping otherwise.
  192.  */
  193. pte_t *ht_mapping_find(as_t *as, __address page)
  194. {
  195.     link_t *hlp;
  196.     pte_t *t = NULL;
  197.     __native key[2] = { (__address) as, page };
  198.    
  199.     spinlock_lock(&page_ht_lock);
  200.  
  201.     hlp = hash_table_find(&page_ht, key);
  202.     if (hlp)
  203.         t = hash_table_get_instance(hlp, pte_t, link);
  204.  
  205.     spinlock_unlock(&page_ht_lock);
  206.     return t;
  207. }
  208.