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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.
  56.  */
  57. SPINLOCK_INITIALIZE(page_ht_lock);
  58.  
  59. /**
  60.  * Page hash table.
  61.  * The page hash table may be accessed only when page_ht_lock is held.
  62.  */
  63. hash_table_t page_ht;
  64.  
  65. /** Hash table operations for page hash table. */
  66. hash_table_operations_t ht_operations = {
  67.     .hash = hash,
  68.     .compare = compare,
  69.     .remove_callback = remove_callback
  70. };
  71.  
  72. /** Page mapping operations for page hash table architectures. */
  73. page_mapping_operations_t ht_mapping_operations = {
  74.     .mapping_insert = ht_mapping_insert,
  75.     .mapping_remove = ht_mapping_remove,
  76.     .mapping_find = ht_mapping_find
  77. };
  78.  
  79. /** Compute page hash table index.
  80.  *
  81.  * @param key Array of two keys (i.e. page and address space).
  82.  *
  83.  * @return Index into page hash table.
  84.  */
  85. index_t hash(__native key[])
  86. {
  87.     as_t *as = (as_t *) key[KEY_AS];
  88.     __address page = (__address) key[KEY_PAGE];
  89.     index_t index;
  90.    
  91.     /*
  92.      * Virtual page addresses have roughly the same probability
  93.      * of occurring. Least significant bits of VPN compose the
  94.      * hash index.
  95.      */
  96.     index = ((page >> PAGE_WIDTH) & (PAGE_HT_ENTRIES-1));
  97.    
  98.     /*
  99.      * Address space structures are likely to be allocated from
  100.      * similar addresses. Least significant bits compose the
  101.      * hash index.
  102.      */
  103.     index |= ((__native) as) & (PAGE_HT_ENTRIES-1);
  104.    
  105.     return index;
  106. }
  107.  
  108. /** Compare page hash table item with page and/or address space.
  109.  *
  110.  * @param key Array of one or two keys (i.e. page and/or address space).
  111.  * @param keys Number of keys passed.
  112.  * @param item Item to compare the keys with.
  113.  *
  114.  * @return true on match, false otherwise.
  115.  */
  116. bool compare(__native key[], count_t keys, link_t *item)
  117. {
  118.     pte_t *t;
  119.  
  120.     ASSERT(item);
  121.     ASSERT((keys > 0) && (keys <= PAGE_HT_KEYS));
  122.  
  123.     /*
  124.      * Convert item to PTE.
  125.      */
  126.     t = hash_table_get_instance(item, pte_t, link);
  127.  
  128.     if (keys == PAGE_HT_KEYS) {
  129.         return (key[KEY_AS] == (__address) t->as) && (key[KEY_PAGE] == t->page);
  130.     } else {
  131.         return (key[KEY_AS] == (__address) t->as);
  132.     }
  133. }
  134.  
  135. /** Callback on page hash table item removal.
  136.  *
  137.  * @param item Page hash table item being removed.
  138.  */
  139. void remove_callback(link_t *item)
  140. {
  141.     pte_t *t;
  142.  
  143.     ASSERT(item);
  144.  
  145.     /*
  146.      * Convert item to PTE.
  147.      */
  148.     t = hash_table_get_instance(item, pte_t, link);
  149.  
  150.     free(t);
  151. }
  152.  
  153. /** Map page to frame using page hash table.
  154.  *
  155.  * Map virtual address 'page' to physical address 'frame'
  156.  * using 'flags'.
  157.  *
  158.  * The address space must be locked and interruptsmust be disabled.
  159.  *
  160.  * @param as Address space to which page belongs.
  161.  * @param page Virtual address of the page to be mapped.
  162.  * @param frame Physical address of memory frame to which the mapping is done.
  163.  * @param flags Flags to be used for mapping.
  164.  */
  165. void ht_mapping_insert(as_t *as, __address page, __address frame, int flags)
  166. {
  167.     pte_t *t;
  168.     __native key[2] = { (__address) as, page = ALIGN_DOWN(page, PAGE_SIZE) };
  169.    
  170.     spinlock_lock(&page_ht_lock);
  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.     spinlock_unlock(&page_ht_lock);
  191. }
  192.  
  193. /** Remove mapping of page from page hash table.
  194.  *
  195.  * Remove any mapping of 'page' within address space 'as'.
  196.  * TLB shootdown should follow in order to make effects of
  197.  * this call visible.
  198.  *
  199.  * The address space must be locked and interrupts must be disabled.
  200.  *
  201.  * @param as Address space to wich page belongs.
  202.  * @param page Virtual address of the page to be demapped.
  203.  */
  204. void ht_mapping_remove(as_t *as, __address page)
  205. {
  206.     __native key[2] = { (__address) as, page = ALIGN_DOWN(page, PAGE_SIZE) };
  207.    
  208.     spinlock_lock(&page_ht_lock);
  209.  
  210.     /*
  211.      * Note that removed PTE's will be freed
  212.      * by remove_callback().
  213.      */
  214.     hash_table_remove(&page_ht, key, 2);
  215.  
  216.     spinlock_unlock(&page_ht_lock);
  217. }
  218.  
  219.  
  220. /** Find mapping for virtual page in page hash table.
  221.  *
  222.  * Find mapping for virtual page.
  223.  *
  224.  * The address space must be locked and interrupts must be disabled.
  225.  *
  226.  * @param as Address space to wich page belongs.
  227.  * @param page Virtual page.
  228.  *
  229.  * @return NULL if there is no such mapping; requested mapping otherwise.
  230.  */
  231. pte_t *ht_mapping_find(as_t *as, __address page)
  232. {
  233.     link_t *hlp;
  234.     pte_t *t = NULL;
  235.     __native key[2] = { (__address) as, page = ALIGN_DOWN(page, PAGE_SIZE) };
  236.    
  237.     spinlock_lock(&page_ht_lock);
  238.  
  239.     hlp = hash_table_find(&page_ht, key);
  240.     if (hlp)
  241.         t = hash_table_get_instance(hlp, pte_t, link);
  242.  
  243.     spinlock_unlock(&page_ht_lock);
  244.     return t;
  245. }
  246.