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  1. /*
  2.  * Copyright (c) 2001-2006 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 genericmm
  30.  * @{
  31.  */
  32.  
  33. /**
  34.  * @file
  35.  * @brief   Address space related functions.
  36.  *
  37.  * This file contains address space manipulation functions.
  38.  * Roughly speaking, this is a higher-level client of
  39.  * Virtual Address Translation (VAT) subsystem.
  40.  *
  41.  * Functionality provided by this file allows one to
  42.  * create address spaces and create, resize and share
  43.  * address space areas.
  44.  *
  45.  * @see page.c
  46.  *
  47.  */
  48.  
  49. #include <mm/as.h>
  50. #include <arch/mm/as.h>
  51. #include <mm/page.h>
  52. #include <mm/frame.h>
  53. #include <mm/slab.h>
  54. #include <mm/tlb.h>
  55. #include <arch/mm/page.h>
  56. #include <genarch/mm/page_pt.h>
  57. #include <genarch/mm/page_ht.h>
  58. #include <mm/asid.h>
  59. #include <arch/mm/asid.h>
  60. #include <synch/spinlock.h>
  61. #include <synch/mutex.h>
  62. #include <adt/list.h>
  63. #include <adt/btree.h>
  64. #include <proc/task.h>
  65. #include <proc/thread.h>
  66. #include <arch/asm.h>
  67. #include <panic.h>
  68. #include <debug.h>
  69. #include <print.h>
  70. #include <memstr.h>
  71. #include <macros.h>
  72. #include <arch.h>
  73. #include <errno.h>
  74. #include <config.h>
  75. #include <align.h>
  76. #include <arch/types.h>
  77. #include <syscall/copy.h>
  78. #include <arch/interrupt.h>
  79.  
  80. #ifdef CONFIG_VIRT_IDX_DCACHE
  81. #include <arch/mm/cache.h>
  82. #endif /* CONFIG_VIRT_IDX_DCACHE */
  83.  
  84. #ifndef __OBJC__
  85. /**
  86.  * Each architecture decides what functions will be used to carry out
  87.  * address space operations such as creating or locking page tables.
  88.  */
  89. as_operations_t *as_operations = NULL;
  90.  
  91. /**
  92.  * Slab for as_t objects.
  93.  */
  94. static slab_cache_t *as_slab;
  95. #endif
  96.  
  97. /**
  98.  * This lock serializes access to the ASID subsystem.
  99.  * It protects:
  100.  * - inactive_as_with_asid_head list
  101.  * - as->asid for each as of the as_t type
  102.  * - asids_allocated counter
  103.  */
  104. SPINLOCK_INITIALIZE(asidlock);
  105.  
  106. /**
  107.  * This list contains address spaces that are not active on any
  108.  * processor and that have valid ASID.
  109.  */
  110. LIST_INITIALIZE(inactive_as_with_asid_head);
  111.  
  112. /** Kernel address space. */
  113. as_t *AS_KERNEL = NULL;
  114.  
  115. static int area_flags_to_page_flags(int aflags);
  116. static as_area_t *find_area_and_lock(as_t *as, uintptr_t va);
  117. static bool check_area_conflicts(as_t *as, uintptr_t va, size_t size,
  118.     as_area_t *avoid_area);
  119. static void sh_info_remove_reference(share_info_t *sh_info);
  120.  
  121. #ifndef __OBJC__
  122. static int as_constructor(void *obj, int flags)
  123. {
  124.     as_t *as = (as_t *) obj;
  125.     int rc;
  126.  
  127.     link_initialize(&as->inactive_as_with_asid_link);
  128.     mutex_initialize(&as->lock);   
  129.    
  130.     rc = as_constructor_arch(as, flags);
  131.    
  132.     return rc;
  133. }
  134.  
  135. static int as_destructor(void *obj)
  136. {
  137.     as_t *as = (as_t *) obj;
  138.  
  139.     return as_destructor_arch(as);
  140. }
  141. #endif
  142.  
  143. /** Initialize address space subsystem. */
  144. void as_init(void)
  145. {
  146.     as_arch_init();
  147.  
  148. #ifndef __OBJC__
  149.     as_slab = slab_cache_create("as_slab", sizeof(as_t), 0,
  150.         as_constructor, as_destructor, SLAB_CACHE_MAGDEFERRED);
  151. #endif
  152.    
  153.     AS_KERNEL = as_create(FLAG_AS_KERNEL);
  154.     if (!AS_KERNEL)
  155.         panic("can't create kernel address space\n");
  156.    
  157. }
  158.  
  159. /** Create address space.
  160.  *
  161.  * @param flags Flags that influence way in wich the address space is created.
  162.  */
  163. as_t *as_create(int flags)
  164. {
  165.     as_t *as;
  166.  
  167. #ifdef __OBJC__
  168.     as = [as_t new];
  169.     link_initialize(&as->inactive_as_with_asid_link);
  170.     mutex_initialize(&as->lock);   
  171.     (void) as_constructor_arch(as, flags);
  172. #else
  173.     as = (as_t *) slab_alloc(as_slab, 0);
  174. #endif
  175.     (void) as_create_arch(as, 0);
  176.    
  177.     btree_create(&as->as_area_btree);
  178.    
  179.     if (flags & FLAG_AS_KERNEL)
  180.         as->asid = ASID_KERNEL;
  181.     else
  182.         as->asid = ASID_INVALID;
  183.    
  184.     as->refcount = 0;
  185.     as->cpu_refcount = 0;
  186. #ifdef AS_PAGE_TABLE
  187.     as->genarch.page_table = page_table_create(flags);
  188. #else
  189.     page_table_create(flags);
  190. #endif
  191.  
  192.     return as;
  193. }
  194.  
  195. /** Destroy adress space.
  196.  *
  197.  * When there are no tasks referencing this address space (i.e. its refcount is
  198.  * zero), the address space can be destroyed.
  199.  */
  200. void as_destroy(as_t *as)
  201. {
  202.     ipl_t ipl;
  203.     bool cond;
  204.  
  205.     ASSERT(as->refcount == 0);
  206.    
  207.     /*
  208.      * Since there is no reference to this area,
  209.      * it is safe not to lock its mutex.
  210.      */
  211.  
  212.     ipl = interrupts_disable();
  213.     spinlock_lock(&asidlock);
  214.     if (as->asid != ASID_INVALID && as != AS_KERNEL) {
  215.         if (as != AS && as->cpu_refcount == 0)
  216.             list_remove(&as->inactive_as_with_asid_link);
  217.         asid_put(as->asid);
  218.     }
  219.     spinlock_unlock(&asidlock);
  220.  
  221.     /*
  222.      * Destroy address space areas of the address space.
  223.      * The B+tree must be walked carefully because it is
  224.      * also being destroyed.
  225.      */
  226.     for (cond = true; cond; ) {
  227.         btree_node_t *node;
  228.  
  229.         ASSERT(!list_empty(&as->as_area_btree.leaf_head));
  230.         node = list_get_instance(as->as_area_btree.leaf_head.next,
  231.             btree_node_t, leaf_link);
  232.  
  233.         if ((cond = node->keys)) {
  234.             as_area_destroy(as, node->key[0]);
  235.         }
  236.     }
  237.  
  238.     btree_destroy(&as->as_area_btree);
  239. #ifdef AS_PAGE_TABLE
  240.     page_table_destroy(as->genarch.page_table);
  241. #else
  242.     page_table_destroy(NULL);
  243. #endif
  244.  
  245.     interrupts_restore(ipl);
  246.  
  247. #ifdef __OBJC__
  248.     [as free];
  249. #else
  250.     slab_free(as_slab, as);
  251. #endif
  252. }
  253.  
  254. /** Create address space area of common attributes.
  255.  *
  256.  * The created address space area is added to the target address space.
  257.  *
  258.  * @param as Target address space.
  259.  * @param flags Flags of the area memory.
  260.  * @param size Size of area.
  261.  * @param base Base address of area.
  262.  * @param attrs Attributes of the area.
  263.  * @param backend Address space area backend. NULL if no backend is used.
  264.  * @param backend_data NULL or a pointer to an array holding two void *.
  265.  *
  266.  * @return Address space area on success or NULL on failure.
  267.  */
  268. as_area_t *
  269. as_area_create(as_t *as, int flags, size_t size, uintptr_t base, int attrs,
  270.            mem_backend_t *backend, mem_backend_data_t *backend_data)
  271. {
  272.     ipl_t ipl;
  273.     as_area_t *a;
  274.    
  275.     if (base % PAGE_SIZE)
  276.         return NULL;
  277.  
  278.     if (!size)
  279.         return NULL;
  280.  
  281.     /* Writeable executable areas are not supported. */
  282.     if ((flags & AS_AREA_EXEC) && (flags & AS_AREA_WRITE))
  283.         return NULL;
  284.    
  285.     ipl = interrupts_disable();
  286.     mutex_lock(&as->lock);
  287.    
  288.     if (!check_area_conflicts(as, base, size, NULL)) {
  289.         mutex_unlock(&as->lock);
  290.         interrupts_restore(ipl);
  291.         return NULL;
  292.     }
  293.    
  294.     a = (as_area_t *) malloc(sizeof(as_area_t), 0);
  295.  
  296.     mutex_initialize(&a->lock);
  297.    
  298.     a->as = as;
  299.     a->flags = flags;
  300.     a->attributes = attrs;
  301.     a->pages = SIZE2FRAMES(size);
  302.     a->base = base;
  303.     a->sh_info = NULL;
  304.     a->backend = backend;
  305.     if (backend_data)
  306.         a->backend_data = *backend_data;
  307.     else
  308.         memsetb((uintptr_t) &a->backend_data, sizeof(a->backend_data),
  309.             0);
  310.  
  311.     btree_create(&a->used_space);
  312.    
  313.     btree_insert(&as->as_area_btree, base, (void *) a, NULL);
  314.  
  315.     mutex_unlock(&as->lock);
  316.     interrupts_restore(ipl);
  317.  
  318.     return a;
  319. }
  320.  
  321. /** Find address space area and change it.
  322.  *
  323.  * @param as Address space.
  324.  * @param address Virtual address belonging to the area to be changed. Must be
  325.  *     page-aligned.
  326.  * @param size New size of the virtual memory block starting at address.
  327.  * @param flags Flags influencing the remap operation. Currently unused.
  328.  *
  329.  * @return Zero on success or a value from @ref errno.h otherwise.
  330.  */
  331. int as_area_resize(as_t *as, uintptr_t address, size_t size, int flags)
  332. {
  333.     as_area_t *area;
  334.     ipl_t ipl;
  335.     size_t pages;
  336.    
  337.     ipl = interrupts_disable();
  338.     mutex_lock(&as->lock);
  339.    
  340.     /*
  341.      * Locate the area.
  342.      */
  343.     area = find_area_and_lock(as, address);
  344.     if (!area) {
  345.         mutex_unlock(&as->lock);
  346.         interrupts_restore(ipl);
  347.         return ENOENT;
  348.     }
  349.  
  350.     if (area->backend == &phys_backend) {
  351.         /*
  352.          * Remapping of address space areas associated
  353.          * with memory mapped devices is not supported.
  354.          */
  355.         mutex_unlock(&area->lock);
  356.         mutex_unlock(&as->lock);
  357.         interrupts_restore(ipl);
  358.         return ENOTSUP;
  359.     }
  360.     if (area->sh_info) {
  361.         /*
  362.          * Remapping of shared address space areas
  363.          * is not supported.
  364.          */
  365.         mutex_unlock(&area->lock);
  366.         mutex_unlock(&as->lock);
  367.         interrupts_restore(ipl);
  368.         return ENOTSUP;
  369.     }
  370.  
  371.     pages = SIZE2FRAMES((address - area->base) + size);
  372.     if (!pages) {
  373.         /*
  374.          * Zero size address space areas are not allowed.
  375.          */
  376.         mutex_unlock(&area->lock);
  377.         mutex_unlock(&as->lock);
  378.         interrupts_restore(ipl);
  379.         return EPERM;
  380.     }
  381.    
  382.     if (pages < area->pages) {
  383.         bool cond;
  384.         uintptr_t start_free = area->base + pages*PAGE_SIZE;
  385.  
  386.         /*
  387.          * Shrinking the area.
  388.          * No need to check for overlaps.
  389.          */
  390.  
  391.         /*
  392.          * Start TLB shootdown sequence.
  393.          */
  394.         tlb_shootdown_start(TLB_INVL_PAGES, AS->asid, area->base +
  395.             pages * PAGE_SIZE, area->pages - pages);
  396.  
  397.         /*
  398.          * Remove frames belonging to used space starting from
  399.          * the highest addresses downwards until an overlap with
  400.          * the resized address space area is found. Note that this
  401.          * is also the right way to remove part of the used_space
  402.          * B+tree leaf list.
  403.          */    
  404.         for (cond = true; cond;) {
  405.             btree_node_t *node;
  406.        
  407.             ASSERT(!list_empty(&area->used_space.leaf_head));
  408.             node =
  409.                 list_get_instance(area->used_space.leaf_head.prev,
  410.                 btree_node_t, leaf_link);
  411.             if ((cond = (bool) node->keys)) {
  412.                 uintptr_t b = node->key[node->keys - 1];
  413.                 count_t c =
  414.                     (count_t) node->value[node->keys - 1];
  415.                 int i = 0;
  416.            
  417.                 if (overlaps(b, c * PAGE_SIZE, area->base,
  418.                     pages * PAGE_SIZE)) {
  419.                    
  420.                     if (b + c * PAGE_SIZE <= start_free) {
  421.                         /*
  422.                          * The whole interval fits
  423.                          * completely in the resized
  424.                          * address space area.
  425.                          */
  426.                         break;
  427.                     }
  428.        
  429.                     /*
  430.                      * Part of the interval corresponding
  431.                      * to b and c overlaps with the resized
  432.                      * address space area.
  433.                      */
  434.        
  435.                     cond = false;   /* we are almost done */
  436.                     i = (start_free - b) >> PAGE_WIDTH;
  437.                     if (!used_space_remove(area, start_free,
  438.                         c - i))
  439.                         panic("Could not remove used "
  440.                             "space.\n");
  441.                 } else {
  442.                     /*
  443.                      * The interval of used space can be
  444.                      * completely removed.
  445.                      */
  446.                     if (!used_space_remove(area, b, c))
  447.                         panic("Could not remove used "
  448.                             "space.\n");
  449.                 }
  450.            
  451.                 for (; i < c; i++) {
  452.                     pte_t *pte;
  453.            
  454.                     page_table_lock(as, false);
  455.                     pte = page_mapping_find(as, b +
  456.                         i * PAGE_SIZE);
  457.                     ASSERT(pte && PTE_VALID(pte) &&
  458.                         PTE_PRESENT(pte));
  459.                     if (area->backend &&
  460.                         area->backend->frame_free) {
  461.                         area->backend->frame_free(area,
  462.                             b + i * PAGE_SIZE,
  463.                             PTE_GET_FRAME(pte));
  464.                     }
  465.                     page_mapping_remove(as, b +
  466.                         i * PAGE_SIZE);
  467.                     page_table_unlock(as, false);
  468.                 }
  469.             }
  470.         }
  471.  
  472.         /*
  473.          * Finish TLB shootdown sequence.
  474.          */
  475.         tlb_invalidate_pages(as->asid, area->base + pages * PAGE_SIZE,
  476.             area->pages - pages);
  477.         tlb_shootdown_finalize();
  478.        
  479.         /*
  480.          * Invalidate software translation caches (e.g. TSB on sparc64).
  481.          */
  482.         as_invalidate_translation_cache(as, area->base +
  483.             pages * PAGE_SIZE, area->pages - pages);
  484.     } else {
  485.         /*
  486.          * Growing the area.
  487.          * Check for overlaps with other address space areas.
  488.          */
  489.         if (!check_area_conflicts(as, address, pages * PAGE_SIZE,
  490.             area)) {
  491.             mutex_unlock(&area->lock);
  492.             mutex_unlock(&as->lock);       
  493.             interrupts_restore(ipl);
  494.             return EADDRNOTAVAIL;
  495.         }
  496.     }
  497.  
  498.     area->pages = pages;
  499.    
  500.     mutex_unlock(&area->lock);
  501.     mutex_unlock(&as->lock);
  502.     interrupts_restore(ipl);
  503.  
  504.     return 0;
  505. }
  506.  
  507. /** Destroy address space area.
  508.  *
  509.  * @param as Address space.
  510.  * @param address Address withing the area to be deleted.
  511.  *
  512.  * @return Zero on success or a value from @ref errno.h on failure.
  513.  */
  514. int as_area_destroy(as_t *as, uintptr_t address)
  515. {
  516.     as_area_t *area;
  517.     uintptr_t base;
  518.     link_t *cur;
  519.     ipl_t ipl;
  520.  
  521.     ipl = interrupts_disable();
  522.     mutex_lock(&as->lock);
  523.  
  524.     area = find_area_and_lock(as, address);
  525.     if (!area) {
  526.         mutex_unlock(&as->lock);
  527.         interrupts_restore(ipl);
  528.         return ENOENT;
  529.     }
  530.  
  531.     base = area->base;
  532.  
  533.     /*
  534.      * Start TLB shootdown sequence.
  535.      */
  536.     tlb_shootdown_start(TLB_INVL_PAGES, as->asid, area->base, area->pages);
  537.  
  538.     /*
  539.      * Visit only the pages mapped by used_space B+tree.
  540.      */
  541.     for (cur = area->used_space.leaf_head.next;
  542.         cur != &area->used_space.leaf_head; cur = cur->next) {
  543.         btree_node_t *node;
  544.         int i;
  545.        
  546.         node = list_get_instance(cur, btree_node_t, leaf_link);
  547.         for (i = 0; i < node->keys; i++) {
  548.             uintptr_t b = node->key[i];
  549.             count_t j;
  550.             pte_t *pte;
  551.            
  552.             for (j = 0; j < (count_t) node->value[i]; j++) {
  553.                 page_table_lock(as, false);
  554.                 pte = page_mapping_find(as, b + j * PAGE_SIZE);
  555.                 ASSERT(pte && PTE_VALID(pte) &&
  556.                     PTE_PRESENT(pte));
  557.                 if (area->backend &&
  558.                     area->backend->frame_free) {
  559.                     area->backend->frame_free(area, b +
  560.                         j * PAGE_SIZE, PTE_GET_FRAME(pte));
  561.                 }
  562.                 page_mapping_remove(as, b + j * PAGE_SIZE);            
  563.                 page_table_unlock(as, false);
  564.             }
  565.         }
  566.     }
  567.  
  568.     /*
  569.      * Finish TLB shootdown sequence.
  570.      */
  571.     tlb_invalidate_pages(as->asid, area->base, area->pages);
  572.     tlb_shootdown_finalize();
  573.    
  574.     /*
  575.      * Invalidate potential software translation caches (e.g. TSB on
  576.      * sparc64).
  577.      */
  578.     as_invalidate_translation_cache(as, area->base, area->pages);
  579.    
  580.     btree_destroy(&area->used_space);
  581.  
  582.     area->attributes |= AS_AREA_ATTR_PARTIAL;
  583.    
  584.     if (area->sh_info)
  585.         sh_info_remove_reference(area->sh_info);
  586.        
  587.     mutex_unlock(&area->lock);
  588.  
  589.     /*
  590.      * Remove the empty area from address space.
  591.      */
  592.     btree_remove(&as->as_area_btree, base, NULL);
  593.    
  594.     free(area);
  595.    
  596.     mutex_unlock(&as->lock);
  597.     interrupts_restore(ipl);
  598.     return 0;
  599. }
  600.  
  601. /** Share address space area with another or the same address space.
  602.  *
  603.  * Address space area mapping is shared with a new address space area.
  604.  * If the source address space area has not been shared so far,
  605.  * a new sh_info is created. The new address space area simply gets the
  606.  * sh_info of the source area. The process of duplicating the
  607.  * mapping is done through the backend share function.
  608.  *
  609.  * @param src_as Pointer to source address space.
  610.  * @param src_base Base address of the source address space area.
  611.  * @param acc_size Expected size of the source area.
  612.  * @param dst_as Pointer to destination address space.
  613.  * @param dst_base Target base address.
  614.  * @param dst_flags_mask Destination address space area flags mask.
  615.  *
  616.  * @return Zero on success or ENOENT if there is no such task or if there is no
  617.  * such address space area, EPERM if there was a problem in accepting the area
  618.  * or ENOMEM if there was a problem in allocating destination address space
  619.  * area. ENOTSUP is returned if the address space area backend does not support
  620.  * sharing.
  621.  */
  622. int as_area_share(as_t *src_as, uintptr_t src_base, size_t acc_size,
  623.           as_t *dst_as, uintptr_t dst_base, int dst_flags_mask)
  624. {
  625.     ipl_t ipl;
  626.     int src_flags;
  627.     size_t src_size;
  628.     as_area_t *src_area, *dst_area;
  629.     share_info_t *sh_info;
  630.     mem_backend_t *src_backend;
  631.     mem_backend_data_t src_backend_data;
  632.    
  633.     ipl = interrupts_disable();
  634.     mutex_lock(&src_as->lock);
  635.     src_area = find_area_and_lock(src_as, src_base);
  636.     if (!src_area) {
  637.         /*
  638.          * Could not find the source address space area.
  639.          */
  640.         mutex_unlock(&src_as->lock);
  641.         interrupts_restore(ipl);
  642.         return ENOENT;
  643.     }
  644.  
  645.     if (!src_area->backend || !src_area->backend->share) {
  646.         /*
  647.          * There is no backend or the backend does not
  648.          * know how to share the area.
  649.          */
  650.         mutex_unlock(&src_area->lock);
  651.         mutex_unlock(&src_as->lock);
  652.         interrupts_restore(ipl);
  653.         return ENOTSUP;
  654.     }
  655.    
  656.     src_size = src_area->pages * PAGE_SIZE;
  657.     src_flags = src_area->flags;
  658.     src_backend = src_area->backend;
  659.     src_backend_data = src_area->backend_data;
  660.  
  661.     /* Share the cacheable flag from the original mapping */
  662.     if (src_flags & AS_AREA_CACHEABLE)
  663.         dst_flags_mask |= AS_AREA_CACHEABLE;
  664.  
  665.     if (src_size != acc_size ||
  666.         (src_flags & dst_flags_mask) != dst_flags_mask) {
  667.         mutex_unlock(&src_area->lock);
  668.         mutex_unlock(&src_as->lock);
  669.         interrupts_restore(ipl);
  670.         return EPERM;
  671.     }
  672.  
  673.     /*
  674.      * Now we are committed to sharing the area.
  675.      * First, prepare the area for sharing.
  676.      * Then it will be safe to unlock it.
  677.      */
  678.     sh_info = src_area->sh_info;
  679.     if (!sh_info) {
  680.         sh_info = (share_info_t *) malloc(sizeof(share_info_t), 0);
  681.         mutex_initialize(&sh_info->lock);
  682.         sh_info->refcount = 2;
  683.         btree_create(&sh_info->pagemap);
  684.         src_area->sh_info = sh_info;
  685.     } else {
  686.         mutex_lock(&sh_info->lock);
  687.         sh_info->refcount++;
  688.         mutex_unlock(&sh_info->lock);
  689.     }
  690.  
  691.     src_area->backend->share(src_area);
  692.  
  693.     mutex_unlock(&src_area->lock);
  694.     mutex_unlock(&src_as->lock);
  695.  
  696.     /*
  697.      * Create copy of the source address space area.
  698.      * The destination area is created with AS_AREA_ATTR_PARTIAL
  699.      * attribute set which prevents race condition with
  700.      * preliminary as_page_fault() calls.
  701.      * The flags of the source area are masked against dst_flags_mask
  702.      * to support sharing in less privileged mode.
  703.      */
  704.     dst_area = as_area_create(dst_as, dst_flags_mask, src_size, dst_base,
  705.         AS_AREA_ATTR_PARTIAL, src_backend, &src_backend_data);
  706.     if (!dst_area) {
  707.         /*
  708.          * Destination address space area could not be created.
  709.          */
  710.         sh_info_remove_reference(sh_info);
  711.        
  712.         interrupts_restore(ipl);
  713.         return ENOMEM;
  714.     }
  715.  
  716.     /*
  717.      * Now the destination address space area has been
  718.      * fully initialized. Clear the AS_AREA_ATTR_PARTIAL
  719.      * attribute and set the sh_info.
  720.      */
  721.     mutex_lock(&dst_as->lock); 
  722.     mutex_lock(&dst_area->lock);
  723.     dst_area->attributes &= ~AS_AREA_ATTR_PARTIAL;
  724.     dst_area->sh_info = sh_info;
  725.     mutex_unlock(&dst_area->lock);
  726.     mutex_unlock(&dst_as->lock);   
  727.  
  728.     interrupts_restore(ipl);
  729.    
  730.     return 0;
  731. }
  732.  
  733. /** Check access mode for address space area.
  734.  *
  735.  * The address space area must be locked prior to this call.
  736.  *
  737.  * @param area Address space area.
  738.  * @param access Access mode.
  739.  *
  740.  * @return False if access violates area's permissions, true otherwise.
  741.  */
  742. bool as_area_check_access(as_area_t *area, pf_access_t access)
  743. {
  744.     int flagmap[] = {
  745.         [PF_ACCESS_READ] = AS_AREA_READ,
  746.         [PF_ACCESS_WRITE] = AS_AREA_WRITE,
  747.         [PF_ACCESS_EXEC] = AS_AREA_EXEC
  748.     };
  749.  
  750.     if (!(area->flags & flagmap[access]))
  751.         return false;
  752.    
  753.     return true;
  754. }
  755.  
  756. /** Handle page fault within the current address space.
  757.  *
  758.  * This is the high-level page fault handler. It decides
  759.  * whether the page fault can be resolved by any backend
  760.  * and if so, it invokes the backend to resolve the page
  761.  * fault.
  762.  *
  763.  * Interrupts are assumed disabled.
  764.  *
  765.  * @param page Faulting page.
  766.  * @param access Access mode that caused the fault (i.e. read/write/exec).
  767.  * @param istate Pointer to interrupted state.
  768.  *
  769.  * @return AS_PF_FAULT on page fault, AS_PF_OK on success or AS_PF_DEFER if the
  770.  *     fault was caused by copy_to_uspace() or copy_from_uspace().
  771.  */
  772. int as_page_fault(uintptr_t page, pf_access_t access, istate_t *istate)
  773. {
  774.     pte_t *pte;
  775.     as_area_t *area;
  776.    
  777.     if (!THREAD)
  778.         return AS_PF_FAULT;
  779.        
  780.     ASSERT(AS);
  781.  
  782.     mutex_lock(&AS->lock);
  783.     area = find_area_and_lock(AS, page);   
  784.     if (!area) {
  785.         /*
  786.          * No area contained mapping for 'page'.
  787.          * Signal page fault to low-level handler.
  788.          */
  789.         mutex_unlock(&AS->lock);
  790.         goto page_fault;
  791.     }
  792.  
  793.     if (area->attributes & AS_AREA_ATTR_PARTIAL) {
  794.         /*
  795.          * The address space area is not fully initialized.
  796.          * Avoid possible race by returning error.
  797.          */
  798.         mutex_unlock(&area->lock);
  799.         mutex_unlock(&AS->lock);
  800.         goto page_fault;       
  801.     }
  802.  
  803.     if (!area->backend || !area->backend->page_fault) {
  804.         /*
  805.          * The address space area is not backed by any backend
  806.          * or the backend cannot handle page faults.
  807.          */
  808.         mutex_unlock(&area->lock);
  809.         mutex_unlock(&AS->lock);
  810.         goto page_fault;       
  811.     }
  812.  
  813.     page_table_lock(AS, false);
  814.    
  815.     /*
  816.      * To avoid race condition between two page faults
  817.      * on the same address, we need to make sure
  818.      * the mapping has not been already inserted.
  819.      */
  820.     if ((pte = page_mapping_find(AS, page))) {
  821.         if (PTE_PRESENT(pte)) {
  822.             if (((access == PF_ACCESS_READ) && PTE_READABLE(pte)) ||
  823.                 (access == PF_ACCESS_WRITE && PTE_WRITABLE(pte)) ||
  824.                 (access == PF_ACCESS_EXEC && PTE_EXECUTABLE(pte))) {
  825.                 page_table_unlock(AS, false);
  826.                 mutex_unlock(&area->lock);
  827.                 mutex_unlock(&AS->lock);
  828.                 return AS_PF_OK;
  829.             }
  830.         }
  831.     }
  832.    
  833.     /*
  834.      * Resort to the backend page fault handler.
  835.      */
  836.     if (area->backend->page_fault(area, page, access) != AS_PF_OK) {
  837.         page_table_unlock(AS, false);
  838.         mutex_unlock(&area->lock);
  839.         mutex_unlock(&AS->lock);
  840.         goto page_fault;
  841.     }
  842.    
  843.     page_table_unlock(AS, false);
  844.     mutex_unlock(&area->lock);
  845.     mutex_unlock(&AS->lock);
  846.     return AS_PF_OK;
  847.  
  848. page_fault:
  849.     if (THREAD->in_copy_from_uspace) {
  850.         THREAD->in_copy_from_uspace = false;
  851.         istate_set_retaddr(istate,
  852.             (uintptr_t) &memcpy_from_uspace_failover_address);
  853.     } else if (THREAD->in_copy_to_uspace) {
  854.         THREAD->in_copy_to_uspace = false;
  855.         istate_set_retaddr(istate,
  856.             (uintptr_t) &memcpy_to_uspace_failover_address);
  857.     } else {
  858.         return AS_PF_FAULT;
  859.     }
  860.  
  861.     return AS_PF_DEFER;
  862. }
  863.  
  864. /** Switch address spaces.
  865.  *
  866.  * Note that this function cannot sleep as it is essentially a part of
  867.  * scheduling. Sleeping here would lead to deadlock on wakeup. Another
  868.  * thing which is forbidden in this context is locking the address space.
  869.  *
  870.  * @param old Old address space or NULL.
  871.  * @param new New address space.
  872.  */
  873. void as_switch(as_t *old_as, as_t *new_as)
  874. {
  875.     spinlock_lock(&asidlock);
  876.  
  877.     /*
  878.      * First, take care of the old address space.
  879.      */
  880.     if (old_as) {
  881.         ASSERT(old_as->cpu_refcount);
  882.         if((--old_as->cpu_refcount == 0) && (old_as != AS_KERNEL)) {
  883.             /*
  884.              * The old address space is no longer active on
  885.              * any processor. It can be appended to the
  886.              * list of inactive address spaces with assigned
  887.              * ASID.
  888.              */
  889.             ASSERT(old_as->asid != ASID_INVALID);
  890.             list_append(&old_as->inactive_as_with_asid_link,
  891.                 &inactive_as_with_asid_head);
  892.         }
  893.  
  894.         /*
  895.          * Perform architecture-specific tasks when the address space
  896.          * is being removed from the CPU.
  897.          */
  898.         as_deinstall_arch(old_as);
  899.     }
  900.  
  901.     /*
  902.      * Second, prepare the new address space.
  903.      */
  904.     if ((new_as->cpu_refcount++ == 0) && (new_as != AS_KERNEL)) {
  905.         if (new_as->asid != ASID_INVALID)
  906.             list_remove(&new_as->inactive_as_with_asid_link);
  907.         else
  908.             new_as->asid = asid_get();
  909.     }
  910. #ifdef AS_PAGE_TABLE
  911.     SET_PTL0_ADDRESS(new_as->genarch.page_table);
  912. #endif
  913.    
  914.     /*
  915.      * Perform architecture-specific steps.
  916.      * (e.g. write ASID to hardware register etc.)
  917.      */
  918.     as_install_arch(new_as);
  919.  
  920.     spinlock_unlock(&asidlock);
  921.    
  922.     AS = new_as;
  923. }
  924.  
  925. /** Convert address space area flags to page flags.
  926.  *
  927.  * @param aflags Flags of some address space area.
  928.  *
  929.  * @return Flags to be passed to page_mapping_insert().
  930.  */
  931. int area_flags_to_page_flags(int aflags)
  932. {
  933.     int flags;
  934.  
  935.     flags = PAGE_USER | PAGE_PRESENT;
  936.    
  937.     if (aflags & AS_AREA_READ)
  938.         flags |= PAGE_READ;
  939.        
  940.     if (aflags & AS_AREA_WRITE)
  941.         flags |= PAGE_WRITE;
  942.    
  943.     if (aflags & AS_AREA_EXEC)
  944.         flags |= PAGE_EXEC;
  945.    
  946.     if (aflags & AS_AREA_CACHEABLE)
  947.         flags |= PAGE_CACHEABLE;
  948.        
  949.     return flags;
  950. }
  951.  
  952. /** Compute flags for virtual address translation subsytem.
  953.  *
  954.  * The address space area must be locked.
  955.  * Interrupts must be disabled.
  956.  *
  957.  * @param a Address space area.
  958.  *
  959.  * @return Flags to be used in page_mapping_insert().
  960.  */
  961. int as_area_get_flags(as_area_t *a)
  962. {
  963.     return area_flags_to_page_flags(a->flags);
  964. }
  965.  
  966. /** Create page table.
  967.  *
  968.  * Depending on architecture, create either address space
  969.  * private or global page table.
  970.  *
  971.  * @param flags Flags saying whether the page table is for kernel address space.
  972.  *
  973.  * @return First entry of the page table.
  974.  */
  975. pte_t *page_table_create(int flags)
  976. {
  977. #ifdef __OBJC__
  978.     return [as_t page_table_create: flags];
  979. #else
  980.     ASSERT(as_operations);
  981.     ASSERT(as_operations->page_table_create);
  982.    
  983.     return as_operations->page_table_create(flags);
  984. #endif
  985. }
  986.  
  987. /** Destroy page table.
  988.  *
  989.  * Destroy page table in architecture specific way.
  990.  *
  991.  * @param page_table Physical address of PTL0.
  992.  */
  993. void page_table_destroy(pte_t *page_table)
  994. {
  995. #ifdef __OBJC__
  996.     return [as_t page_table_destroy: page_table];
  997. #else
  998.     ASSERT(as_operations);
  999.     ASSERT(as_operations->page_table_destroy);
  1000.    
  1001.     as_operations->page_table_destroy(page_table);
  1002. #endif
  1003. }
  1004.  
  1005. /** Lock page table.
  1006.  *
  1007.  * This function should be called before any page_mapping_insert(),
  1008.  * page_mapping_remove() and page_mapping_find().
  1009.  *
  1010.  * Locking order is such that address space areas must be locked
  1011.  * prior to this call. Address space can be locked prior to this
  1012.  * call in which case the lock argument is false.
  1013.  *
  1014.  * @param as Address space.
  1015.  * @param lock If false, do not attempt to lock as->lock.
  1016.  */
  1017. void page_table_lock(as_t *as, bool lock)
  1018. {
  1019. #ifdef __OBJC__
  1020.     [as page_table_lock: lock];
  1021. #else
  1022.     ASSERT(as_operations);
  1023.     ASSERT(as_operations->page_table_lock);
  1024.    
  1025.     as_operations->page_table_lock(as, lock);
  1026. #endif
  1027. }
  1028.  
  1029. /** Unlock page table.
  1030.  *
  1031.  * @param as Address space.
  1032.  * @param unlock If false, do not attempt to unlock as->lock.
  1033.  */
  1034. void page_table_unlock(as_t *as, bool unlock)
  1035. {
  1036. #ifdef __OBJC__
  1037.     [as page_table_unlock: unlock];
  1038. #else
  1039.     ASSERT(as_operations);
  1040.     ASSERT(as_operations->page_table_unlock);
  1041.    
  1042.     as_operations->page_table_unlock(as, unlock);
  1043. #endif
  1044. }
  1045.  
  1046.  
  1047. /** Find address space area and lock it.
  1048.  *
  1049.  * The address space must be locked and interrupts must be disabled.
  1050.  *
  1051.  * @param as Address space.
  1052.  * @param va Virtual address.
  1053.  *
  1054.  * @return Locked address space area containing va on success or NULL on
  1055.  *     failure.
  1056.  */
  1057. as_area_t *find_area_and_lock(as_t *as, uintptr_t va)
  1058. {
  1059.     as_area_t *a;
  1060.     btree_node_t *leaf, *lnode;
  1061.     int i;
  1062.    
  1063.     a = (as_area_t *) btree_search(&as->as_area_btree, va, &leaf);
  1064.     if (a) {
  1065.         /* va is the base address of an address space area */
  1066.         mutex_lock(&a->lock);
  1067.         return a;
  1068.     }
  1069.    
  1070.     /*
  1071.      * Search the leaf node and the righmost record of its left neighbour
  1072.      * to find out whether this is a miss or va belongs to an address
  1073.      * space area found there.
  1074.      */
  1075.    
  1076.     /* First, search the leaf node itself. */
  1077.     for (i = 0; i < leaf->keys; i++) {
  1078.         a = (as_area_t *) leaf->value[i];
  1079.         mutex_lock(&a->lock);
  1080.         if ((a->base <= va) && (va < a->base + a->pages * PAGE_SIZE)) {
  1081.             return a;
  1082.         }
  1083.         mutex_unlock(&a->lock);
  1084.     }
  1085.  
  1086.     /*
  1087.      * Second, locate the left neighbour and test its last record.
  1088.      * Because of its position in the B+tree, it must have base < va.
  1089.      */
  1090.     lnode = btree_leaf_node_left_neighbour(&as->as_area_btree, leaf);
  1091.     if (lnode) {
  1092.         a = (as_area_t *) lnode->value[lnode->keys - 1];
  1093.         mutex_lock(&a->lock);
  1094.         if (va < a->base + a->pages * PAGE_SIZE) {
  1095.             return a;
  1096.         }
  1097.         mutex_unlock(&a->lock);
  1098.     }
  1099.  
  1100.     return NULL;
  1101. }
  1102.  
  1103. /** Check area conflicts with other areas.
  1104.  *
  1105.  * The address space must be locked and interrupts must be disabled.
  1106.  *
  1107.  * @param as Address space.
  1108.  * @param va Starting virtual address of the area being tested.
  1109.  * @param size Size of the area being tested.
  1110.  * @param avoid_area Do not touch this area.
  1111.  *
  1112.  * @return True if there is no conflict, false otherwise.
  1113.  */
  1114. bool check_area_conflicts(as_t *as, uintptr_t va, size_t size,
  1115.               as_area_t *avoid_area)
  1116. {
  1117.     as_area_t *a;
  1118.     btree_node_t *leaf, *node;
  1119.     int i;
  1120.    
  1121.     /*
  1122.      * We don't want any area to have conflicts with NULL page.
  1123.      */
  1124.     if (overlaps(va, size, NULL, PAGE_SIZE))
  1125.         return false;
  1126.    
  1127.     /*
  1128.      * The leaf node is found in O(log n), where n is proportional to
  1129.      * the number of address space areas belonging to as.
  1130.      * The check for conflicts is then attempted on the rightmost
  1131.      * record in the left neighbour, the leftmost record in the right
  1132.      * neighbour and all records in the leaf node itself.
  1133.      */
  1134.    
  1135.     if ((a = (as_area_t *) btree_search(&as->as_area_btree, va, &leaf))) {
  1136.         if (a != avoid_area)
  1137.             return false;
  1138.     }
  1139.    
  1140.     /* First, check the two border cases. */
  1141.     if ((node = btree_leaf_node_left_neighbour(&as->as_area_btree, leaf))) {
  1142.         a = (as_area_t *) node->value[node->keys - 1];
  1143.         mutex_lock(&a->lock);
  1144.         if (overlaps(va, size, a->base, a->pages * PAGE_SIZE)) {
  1145.             mutex_unlock(&a->lock);
  1146.             return false;
  1147.         }
  1148.         mutex_unlock(&a->lock);
  1149.     }
  1150.     node = btree_leaf_node_right_neighbour(&as->as_area_btree, leaf);
  1151.     if (node) {
  1152.         a = (as_area_t *) node->value[0];
  1153.         mutex_lock(&a->lock);
  1154.         if (overlaps(va, size, a->base, a->pages * PAGE_SIZE)) {
  1155.             mutex_unlock(&a->lock);
  1156.             return false;
  1157.         }
  1158.         mutex_unlock(&a->lock);
  1159.     }
  1160.    
  1161.     /* Second, check the leaf node. */
  1162.     for (i = 0; i < leaf->keys; i++) {
  1163.         a = (as_area_t *) leaf->value[i];
  1164.    
  1165.         if (a == avoid_area)
  1166.             continue;
  1167.    
  1168.         mutex_lock(&a->lock);
  1169.         if (overlaps(va, size, a->base, a->pages * PAGE_SIZE)) {
  1170.             mutex_unlock(&a->lock);
  1171.             return false;
  1172.         }
  1173.         mutex_unlock(&a->lock);
  1174.     }
  1175.  
  1176.     /*
  1177.      * So far, the area does not conflict with other areas.
  1178.      * Check if it doesn't conflict with kernel address space.
  1179.      */  
  1180.     if (!KERNEL_ADDRESS_SPACE_SHADOWED) {
  1181.         return !overlaps(va, size,
  1182.             KERNEL_ADDRESS_SPACE_START,
  1183.             KERNEL_ADDRESS_SPACE_END - KERNEL_ADDRESS_SPACE_START);
  1184.     }
  1185.  
  1186.     return true;
  1187. }
  1188.  
  1189. /** Return size of the address space area with given base.  */
  1190. size_t as_get_size(uintptr_t base)
  1191. {
  1192.     ipl_t ipl;
  1193.     as_area_t *src_area;
  1194.     size_t size;
  1195.  
  1196.     ipl = interrupts_disable();
  1197.     src_area = find_area_and_lock(AS, base);
  1198.     if (src_area){
  1199.         size = src_area->pages * PAGE_SIZE;
  1200.         mutex_unlock(&src_area->lock);
  1201.     } else {
  1202.         size = 0;
  1203.     }
  1204.     interrupts_restore(ipl);
  1205.     return size;
  1206. }
  1207.  
  1208. /** Mark portion of address space area as used.
  1209.  *
  1210.  * The address space area must be already locked.
  1211.  *
  1212.  * @param a Address space area.
  1213.  * @param page First page to be marked.
  1214.  * @param count Number of page to be marked.
  1215.  *
  1216.  * @return 0 on failure and 1 on success.
  1217.  */
  1218. int used_space_insert(as_area_t *a, uintptr_t page, count_t count)
  1219. {
  1220.     btree_node_t *leaf, *node;
  1221.     count_t pages;
  1222.     int i;
  1223.  
  1224.     ASSERT(page == ALIGN_DOWN(page, PAGE_SIZE));
  1225.     ASSERT(count);
  1226.  
  1227.     pages = (count_t) btree_search(&a->used_space, page, &leaf);
  1228.     if (pages) {
  1229.         /*
  1230.          * We hit the beginning of some used space.
  1231.          */
  1232.         return 0;
  1233.     }
  1234.  
  1235.     if (!leaf->keys) {
  1236.         btree_insert(&a->used_space, page, (void *) count, leaf);
  1237.         return 1;
  1238.     }
  1239.  
  1240.     node = btree_leaf_node_left_neighbour(&a->used_space, leaf);
  1241.     if (node) {
  1242.         uintptr_t left_pg = node->key[node->keys - 1];
  1243.         uintptr_t right_pg = leaf->key[0];
  1244.         count_t left_cnt = (count_t) node->value[node->keys - 1];
  1245.         count_t right_cnt = (count_t) leaf->value[0];
  1246.        
  1247.         /*
  1248.          * Examine the possibility that the interval fits
  1249.          * somewhere between the rightmost interval of
  1250.          * the left neigbour and the first interval of the leaf.
  1251.          */
  1252.          
  1253.         if (page >= right_pg) {
  1254.             /* Do nothing. */
  1255.         } else if (overlaps(page, count * PAGE_SIZE, left_pg,
  1256.             left_cnt * PAGE_SIZE)) {
  1257.             /* The interval intersects with the left interval. */
  1258.             return 0;
  1259.         } else if (overlaps(page, count * PAGE_SIZE, right_pg,
  1260.             right_cnt * PAGE_SIZE)) {
  1261.             /* The interval intersects with the right interval. */
  1262.             return 0;          
  1263.         } else if ((page == left_pg + left_cnt * PAGE_SIZE) &&
  1264.             (page + count * PAGE_SIZE == right_pg)) {
  1265.             /*
  1266.              * The interval can be added by merging the two already
  1267.              * present intervals.
  1268.              */
  1269.             node->value[node->keys - 1] += count + right_cnt;
  1270.             btree_remove(&a->used_space, right_pg, leaf);
  1271.             return 1;
  1272.         } else if (page == left_pg + left_cnt * PAGE_SIZE) {
  1273.             /*
  1274.              * The interval can be added by simply growing the left
  1275.              * interval.
  1276.              */
  1277.             node->value[node->keys - 1] += count;
  1278.             return 1;
  1279.         } else if (page + count * PAGE_SIZE == right_pg) {
  1280.             /*
  1281.              * The interval can be addded by simply moving base of
  1282.              * the right interval down and increasing its size
  1283.              * accordingly.
  1284.              */
  1285.             leaf->value[0] += count;
  1286.             leaf->key[0] = page;
  1287.             return 1;
  1288.         } else {
  1289.             /*
  1290.              * The interval is between both neigbouring intervals,
  1291.              * but cannot be merged with any of them.
  1292.              */
  1293.             btree_insert(&a->used_space, page, (void *) count,
  1294.                 leaf);
  1295.             return 1;
  1296.         }
  1297.     } else if (page < leaf->key[0]) {
  1298.         uintptr_t right_pg = leaf->key[0];
  1299.         count_t right_cnt = (count_t) leaf->value[0];
  1300.    
  1301.         /*
  1302.          * Investigate the border case in which the left neighbour does
  1303.          * not exist but the interval fits from the left.
  1304.          */
  1305.          
  1306.         if (overlaps(page, count * PAGE_SIZE, right_pg,
  1307.             right_cnt * PAGE_SIZE)) {
  1308.             /* The interval intersects with the right interval. */
  1309.             return 0;
  1310.         } else if (page + count * PAGE_SIZE == right_pg) {
  1311.             /*
  1312.              * The interval can be added by moving the base of the
  1313.              * right interval down and increasing its size
  1314.              * accordingly.
  1315.              */
  1316.             leaf->key[0] = page;
  1317.             leaf->value[0] += count;
  1318.             return 1;
  1319.         } else {
  1320.             /*
  1321.              * The interval doesn't adjoin with the right interval.
  1322.              * It must be added individually.
  1323.              */
  1324.             btree_insert(&a->used_space, page, (void *) count,
  1325.                 leaf);
  1326.             return 1;
  1327.         }
  1328.     }
  1329.  
  1330.     node = btree_leaf_node_right_neighbour(&a->used_space, leaf);
  1331.     if (node) {
  1332.         uintptr_t left_pg = leaf->key[leaf->keys - 1];
  1333.         uintptr_t right_pg = node->key[0];
  1334.         count_t left_cnt = (count_t) leaf->value[leaf->keys - 1];
  1335.         count_t right_cnt = (count_t) node->value[0];
  1336.        
  1337.         /*
  1338.          * Examine the possibility that the interval fits
  1339.          * somewhere between the leftmost interval of
  1340.          * the right neigbour and the last interval of the leaf.
  1341.          */
  1342.  
  1343.         if (page < left_pg) {
  1344.             /* Do nothing. */
  1345.         } else if (overlaps(page, count * PAGE_SIZE, left_pg,
  1346.             left_cnt * PAGE_SIZE)) {
  1347.             /* The interval intersects with the left interval. */
  1348.             return 0;
  1349.         } else if (overlaps(page, count * PAGE_SIZE, right_pg,
  1350.             right_cnt * PAGE_SIZE)) {
  1351.             /* The interval intersects with the right interval. */
  1352.             return 0;          
  1353.         } else if ((page == left_pg + left_cnt * PAGE_SIZE) &&
  1354.             (page + count * PAGE_SIZE == right_pg)) {
  1355.             /*
  1356.              * The interval can be added by merging the two already
  1357.              * present intervals.
  1358.              * */
  1359.             leaf->value[leaf->keys - 1] += count + right_cnt;
  1360.             btree_remove(&a->used_space, right_pg, node);
  1361.             return 1;
  1362.         } else if (page == left_pg + left_cnt * PAGE_SIZE) {
  1363.             /*
  1364.              * The interval can be added by simply growing the left
  1365.              * interval.
  1366.              * */
  1367.             leaf->value[leaf->keys - 1] +=  count;
  1368.             return 1;
  1369.         } else if (page + count * PAGE_SIZE == right_pg) {
  1370.             /*
  1371.              * The interval can be addded by simply moving base of
  1372.              * the right interval down and increasing its size
  1373.              * accordingly.
  1374.              */
  1375.             node->value[0] += count;
  1376.             node->key[0] = page;
  1377.             return 1;
  1378.         } else {
  1379.             /*
  1380.              * The interval is between both neigbouring intervals,
  1381.              * but cannot be merged with any of them.
  1382.              */
  1383.             btree_insert(&a->used_space, page, (void *) count,
  1384.                 leaf);
  1385.             return 1;
  1386.         }
  1387.     } else if (page >= leaf->key[leaf->keys - 1]) {
  1388.         uintptr_t left_pg = leaf->key[leaf->keys - 1];
  1389.         count_t left_cnt = (count_t) leaf->value[leaf->keys - 1];
  1390.    
  1391.         /*
  1392.          * Investigate the border case in which the right neighbour
  1393.          * does not exist but the interval fits from the right.
  1394.          */
  1395.          
  1396.         if (overlaps(page, count * PAGE_SIZE, left_pg,
  1397.             left_cnt * PAGE_SIZE)) {
  1398.             /* The interval intersects with the left interval. */
  1399.             return 0;
  1400.         } else if (left_pg + left_cnt * PAGE_SIZE == page) {
  1401.             /*
  1402.              * The interval can be added by growing the left
  1403.              * interval.
  1404.              */
  1405.             leaf->value[leaf->keys - 1] += count;
  1406.             return 1;
  1407.         } else {
  1408.             /*
  1409.              * The interval doesn't adjoin with the left interval.
  1410.              * It must be added individually.
  1411.              */
  1412.             btree_insert(&a->used_space, page, (void *) count,
  1413.                 leaf);
  1414.             return 1;
  1415.         }
  1416.     }
  1417.    
  1418.     /*
  1419.      * Note that if the algorithm made it thus far, the interval can fit
  1420.      * only between two other intervals of the leaf. The two border cases
  1421.      * were already resolved.
  1422.      */
  1423.     for (i = 1; i < leaf->keys; i++) {
  1424.         if (page < leaf->key[i]) {
  1425.             uintptr_t left_pg = leaf->key[i - 1];
  1426.             uintptr_t right_pg = leaf->key[i];
  1427.             count_t left_cnt = (count_t) leaf->value[i - 1];
  1428.             count_t right_cnt = (count_t) leaf->value[i];
  1429.  
  1430.             /*
  1431.              * The interval fits between left_pg and right_pg.
  1432.              */
  1433.  
  1434.             if (overlaps(page, count * PAGE_SIZE, left_pg,
  1435.                 left_cnt * PAGE_SIZE)) {
  1436.                 /*
  1437.                  * The interval intersects with the left
  1438.                  * interval.
  1439.                  */
  1440.                 return 0;
  1441.             } else if (overlaps(page, count * PAGE_SIZE, right_pg,
  1442.                 right_cnt * PAGE_SIZE)) {
  1443.                 /*
  1444.                  * The interval intersects with the right
  1445.                  * interval.
  1446.                  */
  1447.                 return 0;          
  1448.             } else if ((page == left_pg + left_cnt * PAGE_SIZE) &&
  1449.                 (page + count * PAGE_SIZE == right_pg)) {
  1450.                 /*
  1451.                  * The interval can be added by merging the two
  1452.                  * already present intervals.
  1453.                  */
  1454.                 leaf->value[i - 1] += count + right_cnt;
  1455.                 btree_remove(&a->used_space, right_pg, leaf);
  1456.                 return 1;
  1457.             } else if (page == left_pg + left_cnt * PAGE_SIZE) {
  1458.                 /*
  1459.                  * The interval can be added by simply growing
  1460.                  * the left interval.
  1461.                  */
  1462.                 leaf->value[i - 1] += count;
  1463.                 return 1;
  1464.             } else if (page + count * PAGE_SIZE == right_pg) {
  1465.                 /*
  1466.                      * The interval can be addded by simply moving
  1467.                  * base of the right interval down and
  1468.                  * increasing its size accordingly.
  1469.                  */
  1470.                 leaf->value[i] += count;
  1471.                 leaf->key[i] = page;
  1472.                 return 1;
  1473.             } else {
  1474.                 /*
  1475.                  * The interval is between both neigbouring
  1476.                  * intervals, but cannot be merged with any of
  1477.                  * them.
  1478.                  */
  1479.                 btree_insert(&a->used_space, page,
  1480.                     (void *) count, leaf);
  1481.                 return 1;
  1482.             }
  1483.         }
  1484.     }
  1485.  
  1486.     panic("Inconsistency detected while adding %d pages of used space at "
  1487.         "%p.\n", count, page);
  1488. }
  1489.  
  1490. /** Mark portion of address space area as unused.
  1491.  *
  1492.  * The address space area must be already locked.
  1493.  *
  1494.  * @param a Address space area.
  1495.  * @param page First page to be marked.
  1496.  * @param count Number of page to be marked.
  1497.  *
  1498.  * @return 0 on failure and 1 on success.
  1499.  */
  1500. int used_space_remove(as_area_t *a, uintptr_t page, count_t count)
  1501. {
  1502.     btree_node_t *leaf, *node;
  1503.     count_t pages;
  1504.     int i;
  1505.  
  1506.     ASSERT(page == ALIGN_DOWN(page, PAGE_SIZE));
  1507.     ASSERT(count);
  1508.  
  1509.     pages = (count_t) btree_search(&a->used_space, page, &leaf);
  1510.     if (pages) {
  1511.         /*
  1512.          * We are lucky, page is the beginning of some interval.
  1513.          */
  1514.         if (count > pages) {
  1515.             return 0;
  1516.         } else if (count == pages) {
  1517.             btree_remove(&a->used_space, page, leaf);
  1518.             return 1;
  1519.         } else {
  1520.             /*
  1521.              * Find the respective interval.
  1522.              * Decrease its size and relocate its start address.
  1523.              */
  1524.             for (i = 0; i < leaf->keys; i++) {
  1525.                 if (leaf->key[i] == page) {
  1526.                     leaf->key[i] += count * PAGE_SIZE;
  1527.                     leaf->value[i] -= count;
  1528.                     return 1;
  1529.                 }
  1530.             }
  1531.             goto error;
  1532.         }
  1533.     }
  1534.  
  1535.     node = btree_leaf_node_left_neighbour(&a->used_space, leaf);
  1536.     if (node && page < leaf->key[0]) {
  1537.         uintptr_t left_pg = node->key[node->keys - 1];
  1538.         count_t left_cnt = (count_t) node->value[node->keys - 1];
  1539.  
  1540.         if (overlaps(left_pg, left_cnt * PAGE_SIZE, page,
  1541.             count * PAGE_SIZE)) {
  1542.             if (page + count * PAGE_SIZE ==
  1543.                 left_pg + left_cnt * PAGE_SIZE) {
  1544.                 /*
  1545.                  * The interval is contained in the rightmost
  1546.                  * interval of the left neighbour and can be
  1547.                  * removed by updating the size of the bigger
  1548.                  * interval.
  1549.                  */
  1550.                 node->value[node->keys - 1] -= count;
  1551.                 return 1;
  1552.             } else if (page + count * PAGE_SIZE <
  1553.                 left_pg + left_cnt*PAGE_SIZE) {
  1554.                 count_t new_cnt;
  1555.                
  1556.                 /*
  1557.                  * The interval is contained in the rightmost
  1558.                  * interval of the left neighbour but its
  1559.                  * removal requires both updating the size of
  1560.                  * the original interval and also inserting a
  1561.                  * new interval.
  1562.                  */
  1563.                 new_cnt = ((left_pg + left_cnt * PAGE_SIZE) -
  1564.                     (page + count*PAGE_SIZE)) >> PAGE_WIDTH;
  1565.                 node->value[node->keys - 1] -= count + new_cnt;
  1566.                 btree_insert(&a->used_space, page +
  1567.                     count * PAGE_SIZE, (void *) new_cnt, leaf);
  1568.                 return 1;
  1569.             }
  1570.         }
  1571.         return 0;
  1572.     } else if (page < leaf->key[0]) {
  1573.         return 0;
  1574.     }
  1575.    
  1576.     if (page > leaf->key[leaf->keys - 1]) {
  1577.         uintptr_t left_pg = leaf->key[leaf->keys - 1];
  1578.         count_t left_cnt = (count_t) leaf->value[leaf->keys - 1];
  1579.  
  1580.         if (overlaps(left_pg, left_cnt * PAGE_SIZE, page,
  1581.             count * PAGE_SIZE)) {
  1582.             if (page + count * PAGE_SIZE ==
  1583.                 left_pg + left_cnt * PAGE_SIZE) {
  1584.                 /*
  1585.                  * The interval is contained in the rightmost
  1586.                  * interval of the leaf and can be removed by
  1587.                  * updating the size of the bigger interval.
  1588.                  */
  1589.                 leaf->value[leaf->keys - 1] -= count;
  1590.                 return 1;
  1591.             } else if (page + count * PAGE_SIZE < left_pg +
  1592.                 left_cnt * PAGE_SIZE) {
  1593.                 count_t new_cnt;
  1594.                
  1595.                 /*
  1596.                  * The interval is contained in the rightmost
  1597.                  * interval of the leaf but its removal
  1598.                  * requires both updating the size of the
  1599.                  * original interval and also inserting a new
  1600.                  * interval.
  1601.                  */
  1602.                 new_cnt = ((left_pg + left_cnt * PAGE_SIZE) -
  1603.                     (page + count * PAGE_SIZE)) >> PAGE_WIDTH;
  1604.                 leaf->value[leaf->keys - 1] -= count + new_cnt;
  1605.                 btree_insert(&a->used_space, page +
  1606.                     count * PAGE_SIZE, (void *) new_cnt, leaf);
  1607.                 return 1;
  1608.             }
  1609.         }
  1610.         return 0;
  1611.     }  
  1612.    
  1613.     /*
  1614.      * The border cases have been already resolved.
  1615.      * Now the interval can be only between intervals of the leaf.
  1616.      */
  1617.     for (i = 1; i < leaf->keys - 1; i++) {
  1618.         if (page < leaf->key[i]) {
  1619.             uintptr_t left_pg = leaf->key[i - 1];
  1620.             count_t left_cnt = (count_t) leaf->value[i - 1];
  1621.  
  1622.             /*
  1623.              * Now the interval is between intervals corresponding
  1624.              * to (i - 1) and i.
  1625.              */
  1626.             if (overlaps(left_pg, left_cnt * PAGE_SIZE, page,
  1627.                 count * PAGE_SIZE)) {
  1628.                 if (page + count * PAGE_SIZE ==
  1629.                     left_pg + left_cnt*PAGE_SIZE) {
  1630.                     /*
  1631.                      * The interval is contained in the
  1632.                      * interval (i - 1) of the leaf and can
  1633.                      * be removed by updating the size of
  1634.                      * the bigger interval.
  1635.                      */
  1636.                     leaf->value[i - 1] -= count;
  1637.                     return 1;
  1638.                 } else if (page + count * PAGE_SIZE <
  1639.                     left_pg + left_cnt * PAGE_SIZE) {
  1640.                     count_t new_cnt;
  1641.                
  1642.                     /*
  1643.                      * The interval is contained in the
  1644.                      * interval (i - 1) of the leaf but its
  1645.                      * removal requires both updating the
  1646.                      * size of the original interval and
  1647.                      * also inserting a new interval.
  1648.                      */
  1649.                     new_cnt = ((left_pg +
  1650.                         left_cnt * PAGE_SIZE) -
  1651.                         (page + count * PAGE_SIZE)) >>
  1652.                         PAGE_WIDTH;
  1653.                     leaf->value[i - 1] -= count + new_cnt;
  1654.                     btree_insert(&a->used_space, page +
  1655.                         count * PAGE_SIZE, (void *) new_cnt,
  1656.                         leaf);
  1657.                     return 1;
  1658.                 }
  1659.             }
  1660.             return 0;
  1661.         }
  1662.     }
  1663.  
  1664. error:
  1665.     panic("Inconsistency detected while removing %d pages of used space "
  1666.         "from %p.\n", count, page);
  1667. }
  1668.  
  1669. /** Remove reference to address space area share info.
  1670.  *
  1671.  * If the reference count drops to 0, the sh_info is deallocated.
  1672.  *
  1673.  * @param sh_info Pointer to address space area share info.
  1674.  */
  1675. void sh_info_remove_reference(share_info_t *sh_info)
  1676. {
  1677.     bool dealloc = false;
  1678.  
  1679.     mutex_lock(&sh_info->lock);
  1680.     ASSERT(sh_info->refcount);
  1681.     if (--sh_info->refcount == 0) {
  1682.         dealloc = true;
  1683.         link_t *cur;
  1684.        
  1685.         /*
  1686.          * Now walk carefully the pagemap B+tree and free/remove
  1687.          * reference from all frames found there.
  1688.          */
  1689.         for (cur = sh_info->pagemap.leaf_head.next;
  1690.             cur != &sh_info->pagemap.leaf_head; cur = cur->next) {
  1691.             btree_node_t *node;
  1692.             int i;
  1693.            
  1694.             node = list_get_instance(cur, btree_node_t, leaf_link);
  1695.             for (i = 0; i < node->keys; i++)
  1696.                 frame_free((uintptr_t) node->value[i]);
  1697.         }
  1698.        
  1699.     }
  1700.     mutex_unlock(&sh_info->lock);
  1701.    
  1702.     if (dealloc) {
  1703.         btree_destroy(&sh_info->pagemap);
  1704.         free(sh_info);
  1705.     }
  1706. }
  1707.  
  1708. /*
  1709.  * Address space related syscalls.
  1710.  */
  1711.  
  1712. /** Wrapper for as_area_create(). */
  1713. unative_t sys_as_area_create(uintptr_t address, size_t size, int flags)
  1714. {
  1715.     if (as_area_create(AS, flags | AS_AREA_CACHEABLE, size, address,
  1716.         AS_AREA_ATTR_NONE, &anon_backend, NULL))
  1717.         return (unative_t) address;
  1718.     else
  1719.         return (unative_t) -1;
  1720. }
  1721.  
  1722. /** Wrapper for as_area_resize(). */
  1723. unative_t sys_as_area_resize(uintptr_t address, size_t size, int flags)
  1724. {
  1725.     return (unative_t) as_area_resize(AS, address, size, 0);
  1726. }
  1727.  
  1728. /** Wrapper for as_area_destroy(). */
  1729. unative_t sys_as_area_destroy(uintptr_t address)
  1730. {
  1731.     return (unative_t) as_area_destroy(AS, address);
  1732. }
  1733.  
  1734. /** Print out information about address space.
  1735.  *
  1736.  * @param as Address space.
  1737.  */
  1738. void as_print(as_t *as)
  1739. {
  1740.     ipl_t ipl;
  1741.    
  1742.     ipl = interrupts_disable();
  1743.     mutex_lock(&as->lock);
  1744.    
  1745.     /* print out info about address space areas */
  1746.     link_t *cur;
  1747.     for (cur = as->as_area_btree.leaf_head.next;
  1748.         cur != &as->as_area_btree.leaf_head; cur = cur->next) {
  1749.         btree_node_t *node;
  1750.        
  1751.         node = list_get_instance(cur, btree_node_t, leaf_link);
  1752.        
  1753.         int i;
  1754.         for (i = 0; i < node->keys; i++) {
  1755.             as_area_t *area = node->value[i];
  1756.        
  1757.             mutex_lock(&area->lock);
  1758.             printf("as_area: %p, base=%p, pages=%d (%p - %p)\n",
  1759.                 area, area->base, area->pages, area->base,
  1760.                 area->base + area->pages*PAGE_SIZE);
  1761.             mutex_unlock(&area->lock);
  1762.         }
  1763.     }
  1764.    
  1765.     mutex_unlock(&as->lock);
  1766.     interrupts_restore(ipl);
  1767. }
  1768.  
  1769. /** @}
  1770.  */
  1771.