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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. /**
  30.  * @file    as.c
  31.  * @brief   Address space related functions.
  32.  *
  33.  * This file contains address space manipulation functions.
  34.  * Roughly speaking, this is a higher-level client of
  35.  * Virtual Address Translation (VAT) subsystem.
  36.  *
  37.  * Functionality provided by this file allows one to
  38.  * create address space and create, resize and share
  39.  * address space areas.
  40.  *
  41.  * @see page.c
  42.  *
  43.  */
  44.  
  45. #include <mm/as.h>
  46. #include <arch/mm/as.h>
  47. #include <mm/page.h>
  48. #include <mm/frame.h>
  49. #include <mm/slab.h>
  50. #include <mm/tlb.h>
  51. #include <arch/mm/page.h>
  52. #include <genarch/mm/page_pt.h>
  53. #include <genarch/mm/page_ht.h>
  54. #include <mm/asid.h>
  55. #include <arch/mm/asid.h>
  56. #include <synch/spinlock.h>
  57. #include <synch/mutex.h>
  58. #include <adt/list.h>
  59. #include <adt/btree.h>
  60. #include <proc/task.h>
  61. #include <proc/thread.h>
  62. #include <arch/asm.h>
  63. #include <panic.h>
  64. #include <debug.h>
  65. #include <print.h>
  66. #include <memstr.h>
  67. #include <macros.h>
  68. #include <arch.h>
  69. #include <errno.h>
  70. #include <config.h>
  71. #include <align.h>
  72. #include <arch/types.h>
  73. #include <typedefs.h>
  74. #include <syscall/copy.h>
  75. #include <arch/interrupt.h>
  76.  
  77. as_operations_t *as_operations = NULL;
  78.  
  79. /** This lock protects inactive_as_with_asid_head list. It must be acquired before as_t mutex. */
  80. SPINLOCK_INITIALIZE(inactive_as_with_asid_lock);
  81.  
  82. /**
  83.  * This list contains address spaces that are not active on any
  84.  * processor and that have valid ASID.
  85.  */
  86. LIST_INITIALIZE(inactive_as_with_asid_head);
  87.  
  88. /** Kernel address space. */
  89. as_t *AS_KERNEL = NULL;
  90.  
  91. static int area_flags_to_page_flags(int aflags);
  92. static as_area_t *find_area_and_lock(as_t *as, __address va);
  93. static bool check_area_conflicts(as_t *as, __address va, size_t size, as_area_t *avoid_area);
  94. static void sh_info_remove_reference(share_info_t *sh_info);
  95.  
  96. /** Initialize address space subsystem. */
  97. void as_init(void)
  98. {
  99.     as_arch_init();
  100.     AS_KERNEL = as_create(FLAG_AS_KERNEL);
  101.     if (!AS_KERNEL)
  102.         panic("can't create kernel address space\n");
  103.    
  104. }
  105.  
  106. /** Create address space.
  107.  *
  108.  * @param flags Flags that influence way in wich the address space is created.
  109.  */
  110. as_t *as_create(int flags)
  111. {
  112.     as_t *as;
  113.  
  114.     as = (as_t *) malloc(sizeof(as_t), 0);
  115.     link_initialize(&as->inactive_as_with_asid_link);
  116.     mutex_initialize(&as->lock);
  117.     btree_create(&as->as_area_btree);
  118.    
  119.     if (flags & FLAG_AS_KERNEL)
  120.         as->asid = ASID_KERNEL;
  121.     else
  122.         as->asid = ASID_INVALID;
  123.    
  124.     as->cpu_refcount = 0;
  125.     as->page_table = page_table_create(flags);
  126.  
  127.     return as;
  128. }
  129.  
  130. /** Free Adress space */
  131. void as_free(as_t *as)
  132. {
  133.     ASSERT(as->cpu_refcount == 0);
  134.  
  135.     /* TODO: free as_areas and other resources held by as */
  136.     /* TODO: free page table */
  137.     free(as);
  138. }
  139.  
  140. /** Create address space area of common attributes.
  141.  *
  142.  * The created address space area is added to the target address space.
  143.  *
  144.  * @param as Target address space.
  145.  * @param flags Flags of the area memory.
  146.  * @param size Size of area.
  147.  * @param base Base address of area.
  148.  * @param attrs Attributes of the area.
  149.  * @param backend Address space area backend. NULL if no backend is used.
  150.  * @param backend_data NULL or a pointer to an array holding two void *.
  151.  *
  152.  * @return Address space area on success or NULL on failure.
  153.  */
  154. as_area_t *as_area_create(as_t *as, int flags, size_t size, __address base, int attrs,
  155.            mem_backend_t *backend, mem_backend_data_t *backend_data)
  156. {
  157.     ipl_t ipl;
  158.     as_area_t *a;
  159.    
  160.     if (base % PAGE_SIZE)
  161.         return NULL;
  162.  
  163.     if (!size)
  164.         return NULL;
  165.  
  166.     /* Writeable executable areas are not supported. */
  167.     if ((flags & AS_AREA_EXEC) && (flags & AS_AREA_WRITE))
  168.         return NULL;
  169.    
  170.     ipl = interrupts_disable();
  171.     mutex_lock(&as->lock);
  172.    
  173.     if (!check_area_conflicts(as, base, size, NULL)) {
  174.         mutex_unlock(&as->lock);
  175.         interrupts_restore(ipl);
  176.         return NULL;
  177.     }
  178.    
  179.     a = (as_area_t *) malloc(sizeof(as_area_t), 0);
  180.  
  181.     mutex_initialize(&a->lock);
  182.    
  183.     a->as = as;
  184.     a->flags = flags;
  185.     a->attributes = attrs;
  186.     a->pages = SIZE2FRAMES(size);
  187.     a->base = base;
  188.     a->sh_info = NULL;
  189.     a->backend = backend;
  190.     if (backend_data)
  191.         a->backend_data = *backend_data;
  192.     else
  193.         memsetb((__address) &a->backend_data, sizeof(a->backend_data), 0);
  194.  
  195.     btree_create(&a->used_space);
  196.    
  197.     btree_insert(&as->as_area_btree, base, (void *) a, NULL);
  198.  
  199.     mutex_unlock(&as->lock);
  200.     interrupts_restore(ipl);
  201.  
  202.     return a;
  203. }
  204.  
  205. /** Find address space area and change it.
  206.  *
  207.  * @param as Address space.
  208.  * @param address Virtual address belonging to the area to be changed. Must be page-aligned.
  209.  * @param size New size of the virtual memory block starting at address.
  210.  * @param flags Flags influencing the remap operation. Currently unused.
  211.  *
  212.  * @return Zero on success or a value from @ref errno.h otherwise.
  213.  */
  214. int as_area_resize(as_t *as, __address address, size_t size, int flags)
  215. {
  216.     as_area_t *area;
  217.     ipl_t ipl;
  218.     size_t pages;
  219.    
  220.     ipl = interrupts_disable();
  221.     mutex_lock(&as->lock);
  222.    
  223.     /*
  224.      * Locate the area.
  225.      */
  226.     area = find_area_and_lock(as, address);
  227.     if (!area) {
  228.         mutex_unlock(&as->lock);
  229.         interrupts_restore(ipl);
  230.         return ENOENT;
  231.     }
  232.  
  233.     if (area->backend == &phys_backend) {
  234.         /*
  235.          * Remapping of address space areas associated
  236.          * with memory mapped devices is not supported.
  237.          */
  238.         mutex_unlock(&area->lock);
  239.         mutex_unlock(&as->lock);
  240.         interrupts_restore(ipl);
  241.         return ENOTSUP;
  242.     }
  243.     if (area->sh_info) {
  244.         /*
  245.          * Remapping of shared address space areas
  246.          * is not supported.
  247.          */
  248.         mutex_unlock(&area->lock);
  249.         mutex_unlock(&as->lock);
  250.         interrupts_restore(ipl);
  251.         return ENOTSUP;
  252.     }
  253.  
  254.     pages = SIZE2FRAMES((address - area->base) + size);
  255.     if (!pages) {
  256.         /*
  257.          * Zero size address space areas are not allowed.
  258.          */
  259.         mutex_unlock(&area->lock);
  260.         mutex_unlock(&as->lock);
  261.         interrupts_restore(ipl);
  262.         return EPERM;
  263.     }
  264.    
  265.     if (pages < area->pages) {
  266.         bool cond;
  267.         __address start_free = area->base + pages*PAGE_SIZE;
  268.  
  269.         /*
  270.          * Shrinking the area.
  271.          * No need to check for overlaps.
  272.          */
  273.  
  274.         /*
  275.          * Remove frames belonging to used space starting from
  276.          * the highest addresses downwards until an overlap with
  277.          * the resized address space area is found. Note that this
  278.          * is also the right way to remove part of the used_space
  279.          * B+tree leaf list.
  280.          */    
  281.         for (cond = true; cond;) {
  282.             btree_node_t *node;
  283.        
  284.             ASSERT(!list_empty(&area->used_space.leaf_head));
  285.             node = list_get_instance(area->used_space.leaf_head.prev, btree_node_t, leaf_link);
  286.             if ((cond = (bool) node->keys)) {
  287.                 __address b = node->key[node->keys - 1];
  288.                 count_t c = (count_t) node->value[node->keys - 1];
  289.                 int i = 0;
  290.            
  291.                 if (overlaps(b, c*PAGE_SIZE, area->base, pages*PAGE_SIZE)) {
  292.                    
  293.                     if (b + c*PAGE_SIZE <= start_free) {
  294.                         /*
  295.                          * The whole interval fits completely
  296.                          * in the resized address space area.
  297.                          */
  298.                         break;
  299.                     }
  300.        
  301.                     /*
  302.                      * Part of the interval corresponding to b and c
  303.                      * overlaps with the resized address space area.
  304.                      */
  305.        
  306.                     cond = false;   /* we are almost done */
  307.                     i = (start_free - b) >> PAGE_WIDTH;
  308.                     if (!used_space_remove(area, start_free, c - i))
  309.                         panic("Could not remove used space.");
  310.                 } else {
  311.                     /*
  312.                      * The interval of used space can be completely removed.
  313.                      */
  314.                     if (!used_space_remove(area, b, c))
  315.                         panic("Could not remove used space.\n");
  316.                 }
  317.            
  318.                 for (; i < c; i++) {
  319.                     pte_t *pte;
  320.            
  321.                     page_table_lock(as, false);
  322.                     pte = page_mapping_find(as, b + i*PAGE_SIZE);
  323.                     ASSERT(pte && PTE_VALID(pte) && PTE_PRESENT(pte));
  324.                     if (area->backend && area->backend->frame_free) {
  325.                         area->backend->frame_free(area,
  326.                             b + i*PAGE_SIZE, PTE_GET_FRAME(pte));
  327.                     }
  328.                     page_mapping_remove(as, b + i*PAGE_SIZE);
  329.                     page_table_unlock(as, false);
  330.                 }
  331.             }
  332.         }
  333.         /*
  334.          * Invalidate TLB's.
  335.          */
  336.         tlb_shootdown_start(TLB_INVL_PAGES, AS->asid, area->base + pages*PAGE_SIZE, area->pages - pages);
  337.         tlb_invalidate_pages(AS->asid, area->base + pages*PAGE_SIZE, area->pages - pages);
  338.         tlb_shootdown_finalize();
  339.     } else {
  340.         /*
  341.          * Growing the area.
  342.          * Check for overlaps with other address space areas.
  343.          */
  344.         if (!check_area_conflicts(as, address, pages * PAGE_SIZE, area)) {
  345.             mutex_unlock(&area->lock);
  346.             mutex_unlock(&as->lock);       
  347.             interrupts_restore(ipl);
  348.             return EADDRNOTAVAIL;
  349.         }
  350.     }
  351.  
  352.     area->pages = pages;
  353.    
  354.     mutex_unlock(&area->lock);
  355.     mutex_unlock(&as->lock);
  356.     interrupts_restore(ipl);
  357.  
  358.     return 0;
  359. }
  360.  
  361. /** Destroy address space area.
  362.  *
  363.  * @param as Address space.
  364.  * @param address Address withing the area to be deleted.
  365.  *
  366.  * @return Zero on success or a value from @ref errno.h on failure.
  367.  */
  368. int as_area_destroy(as_t *as, __address address)
  369. {
  370.     as_area_t *area;
  371.     __address base;
  372.     ipl_t ipl;
  373.     bool cond;
  374.  
  375.     ipl = interrupts_disable();
  376.     mutex_lock(&as->lock);
  377.  
  378.     area = find_area_and_lock(as, address);
  379.     if (!area) {
  380.         mutex_unlock(&as->lock);
  381.         interrupts_restore(ipl);
  382.         return ENOENT;
  383.     }
  384.  
  385.     base = area->base;
  386.  
  387.     /*
  388.      * Visit only the pages mapped by used_space B+tree.
  389.      * Note that we must be very careful when walking the tree
  390.      * leaf list and removing used space as the leaf list changes
  391.      * unpredictibly after each remove. The solution is to actually
  392.      * not walk the tree at all, but to remove items from the head
  393.      * of the leaf list until there are some keys left.
  394.      */
  395.     for (cond = true; cond;) {
  396.         btree_node_t *node;
  397.        
  398.         ASSERT(!list_empty(&area->used_space.leaf_head));
  399.         node = list_get_instance(area->used_space.leaf_head.next, btree_node_t, leaf_link);
  400.         if ((cond = (bool) node->keys)) {
  401.             __address b = node->key[0];
  402.             count_t i;
  403.             pte_t *pte;
  404.            
  405.             for (i = 0; i < (count_t) node->value[0]; i++) {
  406.                 page_table_lock(as, false);
  407.                 pte = page_mapping_find(as, b + i*PAGE_SIZE);
  408.                 ASSERT(pte && PTE_VALID(pte) && PTE_PRESENT(pte));
  409.                 if (area->backend && area->backend->frame_free) {
  410.                     area->backend->frame_free(area,
  411.                         b + i*PAGE_SIZE, PTE_GET_FRAME(pte));
  412.                 }
  413.                 page_mapping_remove(as, b + i*PAGE_SIZE);
  414.                 page_table_unlock(as, false);
  415.             }
  416.             if (!used_space_remove(area, b, i))
  417.                 panic("Could not remove used space.\n");
  418.         }
  419.     }
  420.     btree_destroy(&area->used_space);
  421.  
  422.     /*
  423.      * Invalidate TLB's.
  424.      */
  425.     tlb_shootdown_start(TLB_INVL_PAGES, AS->asid, area->base, area->pages);
  426.     tlb_invalidate_pages(AS->asid, area->base, area->pages);
  427.     tlb_shootdown_finalize();
  428.  
  429.     area->attributes |= AS_AREA_ATTR_PARTIAL;
  430.    
  431.     if (area->sh_info)
  432.         sh_info_remove_reference(area->sh_info);
  433.        
  434.     mutex_unlock(&area->lock);
  435.  
  436.     /*
  437.      * Remove the empty area from address space.
  438.      */
  439.     btree_remove(&AS->as_area_btree, base, NULL);
  440.    
  441.     free(area);
  442.    
  443.     mutex_unlock(&AS->lock);
  444.     interrupts_restore(ipl);
  445.     return 0;
  446. }
  447.  
  448. /** Share address space area with another or the same address space.
  449.  *
  450.  * Address space area mapping is shared with a new address space area.
  451.  * If the source address space area has not been shared so far,
  452.  * a new sh_info is created. The new address space area simply gets the
  453.  * sh_info of the source area. The process of duplicating the
  454.  * mapping is done through the backend share function.
  455.  *
  456.  * @param src_as Pointer to source address space.
  457.  * @param src_base Base address of the source address space area.
  458.  * @param acc_size Expected size of the source area.
  459.  * @param dst_base Target base address.
  460.  * @param dst_flags_mask Destination address space area flags mask.
  461.  *
  462.  * @return Zero on success or ENOENT if there is no such task or
  463.  *     if there is no such address space area,
  464.  *     EPERM if there was a problem in accepting the area or
  465.  *     ENOMEM if there was a problem in allocating destination
  466.  *     address space area. ENOTSUP is returned if an attempt
  467.  *     to share non-anonymous address space area is detected.
  468.  */
  469. int as_area_share(as_t *src_as, __address src_base, size_t acc_size,
  470.           __address dst_base, int dst_flags_mask)
  471. {
  472.     ipl_t ipl;
  473.     int src_flags;
  474.     size_t src_size;
  475.     as_area_t *src_area, *dst_area;
  476.     share_info_t *sh_info;
  477.     mem_backend_t *src_backend;
  478.     mem_backend_data_t src_backend_data;
  479.  
  480.     ipl = interrupts_disable();
  481.     mutex_lock(&src_as->lock);
  482.     src_area = find_area_and_lock(src_as, src_base);
  483.     if (!src_area) {
  484.         /*
  485.          * Could not find the source address space area.
  486.          */
  487.         mutex_unlock(&src_as->lock);
  488.         interrupts_restore(ipl);
  489.         return ENOENT;
  490.     }
  491.    
  492.     if (!src_area->backend || !src_area->backend->share) {
  493.         /*
  494.          * There is now backend or the backend does not
  495.          * know how to share the area.
  496.          */
  497.         mutex_unlock(&src_area->lock);
  498.         mutex_unlock(&src_as->lock);
  499.         interrupts_restore(ipl);
  500.         return ENOTSUP;
  501.     }
  502.    
  503.     src_size = src_area->pages * PAGE_SIZE;
  504.     src_flags = src_area->flags;
  505.     src_backend = src_area->backend;
  506.     src_backend_data = src_area->backend_data;
  507.    
  508.     if (src_size != acc_size) {
  509.         mutex_unlock(&src_area->lock);
  510.         mutex_unlock(&src_as->lock);
  511.         interrupts_restore(ipl);
  512.         return EPERM;
  513.     }
  514.  
  515.     /*
  516.      * Now we are committed to sharing the area.
  517.      * First prepare the area for sharing.
  518.      * Then it will be safe to unlock it.
  519.      */
  520.     sh_info = src_area->sh_info;
  521.     if (!sh_info) {
  522.         sh_info = (share_info_t *) malloc(sizeof(share_info_t), 0);
  523.         mutex_initialize(&sh_info->lock);
  524.         sh_info->refcount = 2;
  525.         btree_create(&sh_info->pagemap);
  526.         src_area->sh_info = sh_info;
  527.     } else {
  528.         mutex_lock(&sh_info->lock);
  529.         sh_info->refcount++;
  530.         mutex_unlock(&sh_info->lock);
  531.     }
  532.  
  533.     src_area->backend->share(src_area);
  534.  
  535.     mutex_unlock(&src_area->lock);
  536.     mutex_unlock(&src_as->lock);
  537.  
  538.     /*
  539.      * Create copy of the source address space area.
  540.      * The destination area is created with AS_AREA_ATTR_PARTIAL
  541.      * attribute set which prevents race condition with
  542.      * preliminary as_page_fault() calls.
  543.      * The flags of the source area are masked against dst_flags_mask
  544.      * to support sharing in less privileged mode.
  545.      */
  546.     dst_area = as_area_create(AS, src_flags & dst_flags_mask, src_size, dst_base,
  547.                   AS_AREA_ATTR_PARTIAL, src_backend, &src_backend_data);
  548.     if (!dst_area) {
  549.         /*
  550.          * Destination address space area could not be created.
  551.          */
  552.         sh_info_remove_reference(sh_info);
  553.        
  554.         interrupts_restore(ipl);
  555.         return ENOMEM;
  556.     }
  557.    
  558.     /*
  559.      * Now the destination address space area has been
  560.      * fully initialized. Clear the AS_AREA_ATTR_PARTIAL
  561.      * attribute and set the sh_info.
  562.      */
  563.     mutex_lock(&dst_area->lock);
  564.     dst_area->attributes &= ~AS_AREA_ATTR_PARTIAL;
  565.     dst_area->sh_info = sh_info;
  566.     mutex_unlock(&dst_area->lock);
  567.    
  568.     interrupts_restore(ipl);
  569.    
  570.     return 0;
  571. }
  572.  
  573. /** Check access mode for address space area.
  574.  *
  575.  * The address space area must be locked prior to this call.
  576.  *
  577.  * @param area Address space area.
  578.  * @param access Access mode.
  579.  *
  580.  * @return False if access violates area's permissions, true otherwise.
  581.  */
  582. bool as_area_check_access(as_area_t *area, pf_access_t access)
  583. {
  584.     int flagmap[] = {
  585.         [PF_ACCESS_READ] = AS_AREA_READ,
  586.         [PF_ACCESS_WRITE] = AS_AREA_WRITE,
  587.         [PF_ACCESS_EXEC] = AS_AREA_EXEC
  588.     };
  589.  
  590.     if (!(area->flags & flagmap[access]))
  591.         return false;
  592.    
  593.     return true;
  594. }
  595.  
  596. /** Handle page fault within the current address space.
  597.  *
  598.  * This is the high-level page fault handler. It decides
  599.  * whether the page fault can be resolved by any backend
  600.  * and if so, it invokes the backend to resolve the page
  601.  * fault.
  602.  *
  603.  * Interrupts are assumed disabled.
  604.  *
  605.  * @param page Faulting page.
  606.  * @param access Access mode that caused the fault (i.e. read/write/exec).
  607.  * @param istate Pointer to interrupted state.
  608.  *
  609.  * @return AS_PF_FAULT on page fault, AS_PF_OK on success or AS_PF_DEFER if the
  610.  *     fault was caused by copy_to_uspace() or copy_from_uspace().
  611.  */
  612. int as_page_fault(__address page, pf_access_t access, istate_t *istate)
  613. {
  614.     pte_t *pte;
  615.     as_area_t *area;
  616.    
  617.     if (!THREAD)
  618.         return AS_PF_FAULT;
  619.        
  620.     ASSERT(AS);
  621.  
  622.     mutex_lock(&AS->lock);
  623.     area = find_area_and_lock(AS, page);   
  624.     if (!area) {
  625.         /*
  626.          * No area contained mapping for 'page'.
  627.          * Signal page fault to low-level handler.
  628.          */
  629.         mutex_unlock(&AS->lock);
  630.         goto page_fault;
  631.     }
  632.  
  633.     if (area->attributes & AS_AREA_ATTR_PARTIAL) {
  634.         /*
  635.          * The address space area is not fully initialized.
  636.          * Avoid possible race by returning error.
  637.          */
  638.         mutex_unlock(&area->lock);
  639.         mutex_unlock(&AS->lock);
  640.         goto page_fault;       
  641.     }
  642.  
  643.     if (!area->backend || !area->backend->page_fault) {
  644.         /*
  645.          * The address space area is not backed by any backend
  646.          * or the backend cannot handle page faults.
  647.          */
  648.         mutex_unlock(&area->lock);
  649.         mutex_unlock(&AS->lock);
  650.         goto page_fault;       
  651.     }
  652.  
  653.     page_table_lock(AS, false);
  654.    
  655.     /*
  656.      * To avoid race condition between two page faults
  657.      * on the same address, we need to make sure
  658.      * the mapping has not been already inserted.
  659.      */
  660.     if ((pte = page_mapping_find(AS, page))) {
  661.         if (PTE_PRESENT(pte)) {
  662.             if (((access == PF_ACCESS_READ) && PTE_READABLE(pte)) ||
  663.                 (access == PF_ACCESS_WRITE && PTE_WRITABLE(pte)) ||
  664.                 (access == PF_ACCESS_EXEC && PTE_EXECUTABLE(pte))) {
  665.                 page_table_unlock(AS, false);
  666.                 mutex_unlock(&area->lock);
  667.                 mutex_unlock(&AS->lock);
  668.                 return AS_PF_OK;
  669.             }
  670.         }
  671.     }
  672.    
  673.     /*
  674.      * Resort to the backend page fault handler.
  675.      */
  676.     if (area->backend->page_fault(area, page, access) != AS_PF_OK) {
  677.         page_table_unlock(AS, false);
  678.         mutex_unlock(&area->lock);
  679.         mutex_unlock(&AS->lock);
  680.         goto page_fault;
  681.     }
  682.    
  683.     page_table_unlock(AS, false);
  684.     mutex_unlock(&area->lock);
  685.     mutex_unlock(&AS->lock);
  686.     return AS_PF_OK;
  687.  
  688. page_fault:
  689.     if (THREAD->in_copy_from_uspace) {
  690.         THREAD->in_copy_from_uspace = false;
  691.         istate_set_retaddr(istate, (__address) &memcpy_from_uspace_failover_address);
  692.     } else if (THREAD->in_copy_to_uspace) {
  693.         THREAD->in_copy_to_uspace = false;
  694.         istate_set_retaddr(istate, (__address) &memcpy_to_uspace_failover_address);
  695.     } else {
  696.         return AS_PF_FAULT;
  697.     }
  698.  
  699.     return AS_PF_DEFER;
  700. }
  701.  
  702. /** Switch address spaces.
  703.  *
  704.  * Note that this function cannot sleep as it is essentially a part of
  705.  * scheduling. Sleeping here would lead to deadlock on wakeup.
  706.  *
  707.  * @param old Old address space or NULL.
  708.  * @param new New address space.
  709.  */
  710. void as_switch(as_t *old, as_t *new)
  711. {
  712.     ipl_t ipl;
  713.     bool needs_asid = false;
  714.    
  715.     ipl = interrupts_disable();
  716.     spinlock_lock(&inactive_as_with_asid_lock);
  717.  
  718.     /*
  719.      * First, take care of the old address space.
  720.      */
  721.     if (old) {
  722.         mutex_lock_active(&old->lock);
  723.         ASSERT(old->cpu_refcount);
  724.         if((--old->cpu_refcount == 0) && (old != AS_KERNEL)) {
  725.             /*
  726.              * The old address space is no longer active on
  727.              * any processor. It can be appended to the
  728.              * list of inactive address spaces with assigned
  729.              * ASID.
  730.              */
  731.              ASSERT(old->asid != ASID_INVALID);
  732.              list_append(&old->inactive_as_with_asid_link, &inactive_as_with_asid_head);
  733.         }
  734.         mutex_unlock(&old->lock);
  735.     }
  736.  
  737.     /*
  738.      * Second, prepare the new address space.
  739.      */
  740.     mutex_lock_active(&new->lock);
  741.     if ((new->cpu_refcount++ == 0) && (new != AS_KERNEL)) {
  742.         if (new->asid != ASID_INVALID)
  743.             list_remove(&new->inactive_as_with_asid_link);
  744.         else
  745.             needs_asid = true;  /* defer call to asid_get() until new->lock is released */
  746.     }
  747.     SET_PTL0_ADDRESS(new->page_table);
  748.     mutex_unlock(&new->lock);
  749.  
  750.     if (needs_asid) {
  751.         /*
  752.          * Allocation of new ASID was deferred
  753.          * until now in order to avoid deadlock.
  754.          */
  755.         asid_t asid;
  756.        
  757.         asid = asid_get();
  758.         mutex_lock_active(&new->lock);
  759.         new->asid = asid;
  760.         mutex_unlock(&new->lock);
  761.     }
  762.     spinlock_unlock(&inactive_as_with_asid_lock);
  763.     interrupts_restore(ipl);
  764.    
  765.     /*
  766.      * Perform architecture-specific steps.
  767.      * (e.g. write ASID to hardware register etc.)
  768.      */
  769.     as_install_arch(new);
  770.    
  771.     AS = new;
  772. }
  773.  
  774. /** Convert address space area flags to page flags.
  775.  *
  776.  * @param aflags Flags of some address space area.
  777.  *
  778.  * @return Flags to be passed to page_mapping_insert().
  779.  */
  780. int area_flags_to_page_flags(int aflags)
  781. {
  782.     int flags;
  783.  
  784.     flags = PAGE_USER | PAGE_PRESENT;
  785.    
  786.     if (aflags & AS_AREA_READ)
  787.         flags |= PAGE_READ;
  788.        
  789.     if (aflags & AS_AREA_WRITE)
  790.         flags |= PAGE_WRITE;
  791.    
  792.     if (aflags & AS_AREA_EXEC)
  793.         flags |= PAGE_EXEC;
  794.    
  795.     if (aflags & AS_AREA_CACHEABLE)
  796.         flags |= PAGE_CACHEABLE;
  797.        
  798.     return flags;
  799. }
  800.  
  801. /** Compute flags for virtual address translation subsytem.
  802.  *
  803.  * The address space area must be locked.
  804.  * Interrupts must be disabled.
  805.  *
  806.  * @param a Address space area.
  807.  *
  808.  * @return Flags to be used in page_mapping_insert().
  809.  */
  810. int as_area_get_flags(as_area_t *a)
  811. {
  812.     return area_flags_to_page_flags(a->flags);
  813. }
  814.  
  815. /** Create page table.
  816.  *
  817.  * Depending on architecture, create either address space
  818.  * private or global page table.
  819.  *
  820.  * @param flags Flags saying whether the page table is for kernel address space.
  821.  *
  822.  * @return First entry of the page table.
  823.  */
  824. pte_t *page_table_create(int flags)
  825. {
  826.         ASSERT(as_operations);
  827.         ASSERT(as_operations->page_table_create);
  828.  
  829.         return as_operations->page_table_create(flags);
  830. }
  831.  
  832. /** Lock page table.
  833.  *
  834.  * This function should be called before any page_mapping_insert(),
  835.  * page_mapping_remove() and page_mapping_find().
  836.  *
  837.  * Locking order is such that address space areas must be locked
  838.  * prior to this call. Address space can be locked prior to this
  839.  * call in which case the lock argument is false.
  840.  *
  841.  * @param as Address space.
  842.  * @param lock If false, do not attempt to lock as->lock.
  843.  */
  844. void page_table_lock(as_t *as, bool lock)
  845. {
  846.     ASSERT(as_operations);
  847.     ASSERT(as_operations->page_table_lock);
  848.  
  849.     as_operations->page_table_lock(as, lock);
  850. }
  851.  
  852. /** Unlock page table.
  853.  *
  854.  * @param as Address space.
  855.  * @param unlock If false, do not attempt to unlock as->lock.
  856.  */
  857. void page_table_unlock(as_t *as, bool unlock)
  858. {
  859.     ASSERT(as_operations);
  860.     ASSERT(as_operations->page_table_unlock);
  861.  
  862.     as_operations->page_table_unlock(as, unlock);
  863. }
  864.  
  865.  
  866. /** Find address space area and lock it.
  867.  *
  868.  * The address space must be locked and interrupts must be disabled.
  869.  *
  870.  * @param as Address space.
  871.  * @param va Virtual address.
  872.  *
  873.  * @return Locked address space area containing va on success or NULL on failure.
  874.  */
  875. as_area_t *find_area_and_lock(as_t *as, __address va)
  876. {
  877.     as_area_t *a;
  878.     btree_node_t *leaf, *lnode;
  879.     int i;
  880.    
  881.     a = (as_area_t *) btree_search(&as->as_area_btree, va, &leaf);
  882.     if (a) {
  883.         /* va is the base address of an address space area */
  884.         mutex_lock(&a->lock);
  885.         return a;
  886.     }
  887.    
  888.     /*
  889.      * Search the leaf node and the righmost record of its left neighbour
  890.      * to find out whether this is a miss or va belongs to an address
  891.      * space area found there.
  892.      */
  893.    
  894.     /* First, search the leaf node itself. */
  895.     for (i = 0; i < leaf->keys; i++) {
  896.         a = (as_area_t *) leaf->value[i];
  897.         mutex_lock(&a->lock);
  898.         if ((a->base <= va) && (va < a->base + a->pages * PAGE_SIZE)) {
  899.             return a;
  900.         }
  901.         mutex_unlock(&a->lock);
  902.     }
  903.  
  904.     /*
  905.      * Second, locate the left neighbour and test its last record.
  906.      * Because of its position in the B+tree, it must have base < va.
  907.      */
  908.     if ((lnode = btree_leaf_node_left_neighbour(&as->as_area_btree, leaf))) {
  909.         a = (as_area_t *) lnode->value[lnode->keys - 1];
  910.         mutex_lock(&a->lock);
  911.         if (va < a->base + a->pages * PAGE_SIZE) {
  912.             return a;
  913.         }
  914.         mutex_unlock(&a->lock);
  915.     }
  916.  
  917.     return NULL;
  918. }
  919.  
  920. /** Check area conflicts with other areas.
  921.  *
  922.  * The address space must be locked and interrupts must be disabled.
  923.  *
  924.  * @param as Address space.
  925.  * @param va Starting virtual address of the area being tested.
  926.  * @param size Size of the area being tested.
  927.  * @param avoid_area Do not touch this area.
  928.  *
  929.  * @return True if there is no conflict, false otherwise.
  930.  */
  931. bool check_area_conflicts(as_t *as, __address va, size_t size, as_area_t *avoid_area)
  932. {
  933.     as_area_t *a;
  934.     btree_node_t *leaf, *node;
  935.     int i;
  936.    
  937.     /*
  938.      * We don't want any area to have conflicts with NULL page.
  939.      */
  940.     if (overlaps(va, size, NULL, PAGE_SIZE))
  941.         return false;
  942.    
  943.     /*
  944.      * The leaf node is found in O(log n), where n is proportional to
  945.      * the number of address space areas belonging to as.
  946.      * The check for conflicts is then attempted on the rightmost
  947.      * record in the left neighbour, the leftmost record in the right
  948.      * neighbour and all records in the leaf node itself.
  949.      */
  950.    
  951.     if ((a = (as_area_t *) btree_search(&as->as_area_btree, va, &leaf))) {
  952.         if (a != avoid_area)
  953.             return false;
  954.     }
  955.    
  956.     /* First, check the two border cases. */
  957.     if ((node = btree_leaf_node_left_neighbour(&as->as_area_btree, leaf))) {
  958.         a = (as_area_t *) node->value[node->keys - 1];
  959.         mutex_lock(&a->lock);
  960.         if (overlaps(va, size, a->base, a->pages * PAGE_SIZE)) {
  961.             mutex_unlock(&a->lock);
  962.             return false;
  963.         }
  964.         mutex_unlock(&a->lock);
  965.     }
  966.     if ((node = btree_leaf_node_right_neighbour(&as->as_area_btree, leaf))) {
  967.         a = (as_area_t *) node->value[0];
  968.         mutex_lock(&a->lock);
  969.         if (overlaps(va, size, a->base, a->pages * PAGE_SIZE)) {
  970.             mutex_unlock(&a->lock);
  971.             return false;
  972.         }
  973.         mutex_unlock(&a->lock);
  974.     }
  975.    
  976.     /* Second, check the leaf node. */
  977.     for (i = 0; i < leaf->keys; i++) {
  978.         a = (as_area_t *) leaf->value[i];
  979.    
  980.         if (a == avoid_area)
  981.             continue;
  982.    
  983.         mutex_lock(&a->lock);
  984.         if (overlaps(va, size, a->base, a->pages * PAGE_SIZE)) {
  985.             mutex_unlock(&a->lock);
  986.             return false;
  987.         }
  988.         mutex_unlock(&a->lock);
  989.     }
  990.  
  991.     /*
  992.      * So far, the area does not conflict with other areas.
  993.      * Check if it doesn't conflict with kernel address space.
  994.      */  
  995.     if (!KERNEL_ADDRESS_SPACE_SHADOWED) {
  996.         return !overlaps(va, size,
  997.             KERNEL_ADDRESS_SPACE_START, KERNEL_ADDRESS_SPACE_END-KERNEL_ADDRESS_SPACE_START);
  998.     }
  999.  
  1000.     return true;
  1001. }
  1002.  
  1003. /** Return size of the address space area with given base.  */
  1004. size_t as_get_size(__address base)
  1005. {
  1006.     ipl_t ipl;
  1007.     as_area_t *src_area;
  1008.     size_t size;
  1009.  
  1010.     ipl = interrupts_disable();
  1011.     src_area = find_area_and_lock(AS, base);
  1012.     if (src_area){
  1013.         size = src_area->pages * PAGE_SIZE;
  1014.         mutex_unlock(&src_area->lock);
  1015.     } else {
  1016.         size = 0;
  1017.     }
  1018.     interrupts_restore(ipl);
  1019.     return size;
  1020. }
  1021.  
  1022. /** Mark portion of address space area as used.
  1023.  *
  1024.  * The address space area must be already locked.
  1025.  *
  1026.  * @param a Address space area.
  1027.  * @param page First page to be marked.
  1028.  * @param count Number of page to be marked.
  1029.  *
  1030.  * @return 0 on failure and 1 on success.
  1031.  */
  1032. int used_space_insert(as_area_t *a, __address page, count_t count)
  1033. {
  1034.     btree_node_t *leaf, *node;
  1035.     count_t pages;
  1036.     int i;
  1037.  
  1038.     ASSERT(page == ALIGN_DOWN(page, PAGE_SIZE));
  1039.     ASSERT(count);
  1040.  
  1041.     pages = (count_t) btree_search(&a->used_space, page, &leaf);
  1042.     if (pages) {
  1043.         /*
  1044.          * We hit the beginning of some used space.
  1045.          */
  1046.         return 0;
  1047.     }
  1048.  
  1049.     node = btree_leaf_node_left_neighbour(&a->used_space, leaf);
  1050.     if (node) {
  1051.         __address left_pg = node->key[node->keys - 1], right_pg = leaf->key[0];
  1052.         count_t left_cnt = (count_t) node->value[node->keys - 1], right_cnt = (count_t) leaf->value[0];
  1053.        
  1054.         /*
  1055.          * Examine the possibility that the interval fits
  1056.          * somewhere between the rightmost interval of
  1057.          * the left neigbour and the first interval of the leaf.
  1058.          */
  1059.          
  1060.         if (page >= right_pg) {
  1061.             /* Do nothing. */
  1062.         } else if (overlaps(page, count*PAGE_SIZE, left_pg, left_cnt*PAGE_SIZE)) {
  1063.             /* The interval intersects with the left interval. */
  1064.             return 0;
  1065.         } else if (overlaps(page, count*PAGE_SIZE, right_pg, right_cnt*PAGE_SIZE)) {
  1066.             /* The interval intersects with the right interval. */
  1067.             return 0;          
  1068.         } else if ((page == left_pg + left_cnt*PAGE_SIZE) && (page + count*PAGE_SIZE == right_pg)) {
  1069.             /* The interval can be added by merging the two already present intervals. */
  1070.             node->value[node->keys - 1] += count + right_cnt;
  1071.             btree_remove(&a->used_space, right_pg, leaf);
  1072.             return 1;
  1073.         } else if (page == left_pg + left_cnt*PAGE_SIZE) {
  1074.             /* The interval can be added by simply growing the left interval. */
  1075.             node->value[node->keys - 1] += count;
  1076.             return 1;
  1077.         } else if (page + count*PAGE_SIZE == right_pg) {
  1078.             /*
  1079.              * The interval can be addded by simply moving base of the right
  1080.              * interval down and increasing its size accordingly.
  1081.              */
  1082.             leaf->value[0] += count;
  1083.             leaf->key[0] = page;
  1084.             return 1;
  1085.         } else {
  1086.             /*
  1087.              * The interval is between both neigbouring intervals,
  1088.              * but cannot be merged with any of them.
  1089.              */
  1090.             btree_insert(&a->used_space, page, (void *) count, leaf);
  1091.             return 1;
  1092.         }
  1093.     } else if (page < leaf->key[0]) {
  1094.         __address right_pg = leaf->key[0];
  1095.         count_t right_cnt = (count_t) leaf->value[0];
  1096.    
  1097.         /*
  1098.          * Investigate the border case in which the left neighbour does not
  1099.          * exist but the interval fits from the left.
  1100.          */
  1101.          
  1102.         if (overlaps(page, count*PAGE_SIZE, right_pg, right_cnt*PAGE_SIZE)) {
  1103.             /* The interval intersects with the right interval. */
  1104.             return 0;
  1105.         } else if (page + count*PAGE_SIZE == right_pg) {
  1106.             /*
  1107.              * The interval can be added by moving the base of the right interval down
  1108.              * and increasing its size accordingly.
  1109.              */
  1110.             leaf->key[0] = page;
  1111.             leaf->value[0] += count;
  1112.             return 1;
  1113.         } else {
  1114.             /*
  1115.              * The interval doesn't adjoin with the right interval.
  1116.              * It must be added individually.
  1117.              */
  1118.             btree_insert(&a->used_space, page, (void *) count, leaf);
  1119.             return 1;
  1120.         }
  1121.     }
  1122.  
  1123.     node = btree_leaf_node_right_neighbour(&a->used_space, leaf);
  1124.     if (node) {
  1125.         __address left_pg = leaf->key[leaf->keys - 1], right_pg = node->key[0];
  1126.         count_t left_cnt = (count_t) leaf->value[leaf->keys - 1], right_cnt = (count_t) node->value[0];
  1127.        
  1128.         /*
  1129.          * Examine the possibility that the interval fits
  1130.          * somewhere between the leftmost interval of
  1131.          * the right neigbour and the last interval of the leaf.
  1132.          */
  1133.  
  1134.         if (page < left_pg) {
  1135.             /* Do nothing. */
  1136.         } else if (overlaps(page, count*PAGE_SIZE, left_pg, left_cnt*PAGE_SIZE)) {
  1137.             /* The interval intersects with the left interval. */
  1138.             return 0;
  1139.         } else if (overlaps(page, count*PAGE_SIZE, right_pg, right_cnt*PAGE_SIZE)) {
  1140.             /* The interval intersects with the right interval. */
  1141.             return 0;          
  1142.         } else if ((page == left_pg + left_cnt*PAGE_SIZE) && (page + count*PAGE_SIZE == right_pg)) {
  1143.             /* The interval can be added by merging the two already present intervals. */
  1144.             leaf->value[leaf->keys - 1] += count + right_cnt;
  1145.             btree_remove(&a->used_space, right_pg, node);
  1146.             return 1;
  1147.         } else if (page == left_pg + left_cnt*PAGE_SIZE) {
  1148.             /* The interval can be added by simply growing the left interval. */
  1149.             leaf->value[leaf->keys - 1] +=  count;
  1150.             return 1;
  1151.         } else if (page + count*PAGE_SIZE == right_pg) {
  1152.             /*
  1153.              * The interval can be addded by simply moving base of the right
  1154.              * interval down and increasing its size accordingly.
  1155.              */
  1156.             node->value[0] += count;
  1157.             node->key[0] = page;
  1158.             return 1;
  1159.         } else {
  1160.             /*
  1161.              * The interval is between both neigbouring intervals,
  1162.              * but cannot be merged with any of them.
  1163.              */
  1164.             btree_insert(&a->used_space, page, (void *) count, leaf);
  1165.             return 1;
  1166.         }
  1167.     } else if (page >= leaf->key[leaf->keys - 1]) {
  1168.         __address left_pg = leaf->key[leaf->keys - 1];
  1169.         count_t left_cnt = (count_t) leaf->value[leaf->keys - 1];
  1170.    
  1171.         /*
  1172.          * Investigate the border case in which the right neighbour does not
  1173.          * exist but the interval fits from the right.
  1174.          */
  1175.          
  1176.         if (overlaps(page, count*PAGE_SIZE, left_pg, left_cnt*PAGE_SIZE)) {
  1177.             /* The interval intersects with the left interval. */
  1178.             return 0;
  1179.         } else if (left_pg + left_cnt*PAGE_SIZE == page) {
  1180.             /* The interval can be added by growing the left interval. */
  1181.             leaf->value[leaf->keys - 1] += count;
  1182.             return 1;
  1183.         } else {
  1184.             /*
  1185.              * The interval doesn't adjoin with the left interval.
  1186.              * It must be added individually.
  1187.              */
  1188.             btree_insert(&a->used_space, page, (void *) count, leaf);
  1189.             return 1;
  1190.         }
  1191.     }
  1192.    
  1193.     /*
  1194.      * Note that if the algorithm made it thus far, the interval can fit only
  1195.      * between two other intervals of the leaf. The two border cases were already
  1196.      * resolved.
  1197.      */
  1198.     for (i = 1; i < leaf->keys; i++) {
  1199.         if (page < leaf->key[i]) {
  1200.             __address left_pg = leaf->key[i - 1], right_pg = leaf->key[i];
  1201.             count_t left_cnt = (count_t) leaf->value[i - 1], right_cnt = (count_t) leaf->value[i];
  1202.  
  1203.             /*
  1204.              * The interval fits between left_pg and right_pg.
  1205.              */
  1206.  
  1207.             if (overlaps(page, count*PAGE_SIZE, left_pg, left_cnt*PAGE_SIZE)) {
  1208.                 /* The interval intersects with the left interval. */
  1209.                 return 0;
  1210.             } else if (overlaps(page, count*PAGE_SIZE, right_pg, right_cnt*PAGE_SIZE)) {
  1211.                 /* The interval intersects with the right interval. */
  1212.                 return 0;          
  1213.             } else if ((page == left_pg + left_cnt*PAGE_SIZE) && (page + count*PAGE_SIZE == right_pg)) {
  1214.                 /* The interval can be added by merging the two already present intervals. */
  1215.                 leaf->value[i - 1] += count + right_cnt;
  1216.                 btree_remove(&a->used_space, right_pg, leaf);
  1217.                 return 1;
  1218.             } else if (page == left_pg + left_cnt*PAGE_SIZE) {
  1219.                 /* The interval can be added by simply growing the left interval. */
  1220.                 leaf->value[i - 1] += count;
  1221.                 return 1;
  1222.             } else if (page + count*PAGE_SIZE == right_pg) {
  1223.                 /*
  1224.                      * The interval can be addded by simply moving base of the right
  1225.                  * interval down and increasing its size accordingly.
  1226.                  */
  1227.                 leaf->value[i] += count;
  1228.                 leaf->key[i] = page;
  1229.                 return 1;
  1230.             } else {
  1231.                 /*
  1232.                  * The interval is between both neigbouring intervals,
  1233.                  * but cannot be merged with any of them.
  1234.                  */
  1235.                 btree_insert(&a->used_space, page, (void *) count, leaf);
  1236.                 return 1;
  1237.             }
  1238.         }
  1239.     }
  1240.  
  1241.     panic("Inconsistency detected while adding %d pages of used space at %P.\n", count, page);
  1242. }
  1243.  
  1244. /** Mark portion of address space area as unused.
  1245.  *
  1246.  * The address space area must be already locked.
  1247.  *
  1248.  * @param a Address space area.
  1249.  * @param page First page to be marked.
  1250.  * @param count Number of page to be marked.
  1251.  *
  1252.  * @return 0 on failure and 1 on success.
  1253.  */
  1254. int used_space_remove(as_area_t *a, __address page, count_t count)
  1255. {
  1256.     btree_node_t *leaf, *node;
  1257.     count_t pages;
  1258.     int i;
  1259.  
  1260.     ASSERT(page == ALIGN_DOWN(page, PAGE_SIZE));
  1261.     ASSERT(count);
  1262.  
  1263.     pages = (count_t) btree_search(&a->used_space, page, &leaf);
  1264.     if (pages) {
  1265.         /*
  1266.          * We are lucky, page is the beginning of some interval.
  1267.          */
  1268.         if (count > pages) {
  1269.             return 0;
  1270.         } else if (count == pages) {
  1271.             btree_remove(&a->used_space, page, leaf);
  1272.             return 1;
  1273.         } else {
  1274.             /*
  1275.              * Find the respective interval.
  1276.              * Decrease its size and relocate its start address.
  1277.              */
  1278.             for (i = 0; i < leaf->keys; i++) {
  1279.                 if (leaf->key[i] == page) {
  1280.                     leaf->key[i] += count*PAGE_SIZE;
  1281.                     leaf->value[i] -= count;
  1282.                     return 1;
  1283.                 }
  1284.             }
  1285.             goto error;
  1286.         }
  1287.     }
  1288.  
  1289.     node = btree_leaf_node_left_neighbour(&a->used_space, leaf);
  1290.     if (node && page < leaf->key[0]) {
  1291.         __address left_pg = node->key[node->keys - 1];
  1292.         count_t left_cnt = (count_t) node->value[node->keys - 1];
  1293.  
  1294.         if (overlaps(left_pg, left_cnt*PAGE_SIZE, page, count*PAGE_SIZE)) {
  1295.             if (page + count*PAGE_SIZE == left_pg + left_cnt*PAGE_SIZE) {
  1296.                 /*
  1297.                  * The interval is contained in the rightmost interval
  1298.                  * of the left neighbour and can be removed by
  1299.                  * updating the size of the bigger interval.
  1300.                  */
  1301.                 node->value[node->keys - 1] -= count;
  1302.                 return 1;
  1303.             } else if (page + count*PAGE_SIZE < left_pg + left_cnt*PAGE_SIZE) {
  1304.                 count_t new_cnt;
  1305.                
  1306.                 /*
  1307.                  * The interval is contained in the rightmost interval
  1308.                  * of the left neighbour but its removal requires
  1309.                  * both updating the size of the original interval and
  1310.                  * also inserting a new interval.
  1311.                  */
  1312.                 new_cnt = ((left_pg + left_cnt*PAGE_SIZE) - (page + count*PAGE_SIZE)) >> PAGE_WIDTH;
  1313.                 node->value[node->keys - 1] -= count + new_cnt;
  1314.                 btree_insert(&a->used_space, page + count*PAGE_SIZE, (void *) new_cnt, leaf);
  1315.                 return 1;
  1316.             }
  1317.         }
  1318.         return 0;
  1319.     } else if (page < leaf->key[0]) {
  1320.         return 0;
  1321.     }
  1322.    
  1323.     if (page > leaf->key[leaf->keys - 1]) {
  1324.         __address left_pg = leaf->key[leaf->keys - 1];
  1325.         count_t left_cnt = (count_t) leaf->value[leaf->keys - 1];
  1326.  
  1327.         if (overlaps(left_pg, left_cnt*PAGE_SIZE, page, count*PAGE_SIZE)) {
  1328.             if (page + count*PAGE_SIZE == left_pg + left_cnt*PAGE_SIZE) {
  1329.                 /*
  1330.                  * The interval is contained in the rightmost interval
  1331.                  * of the leaf and can be removed by updating the size
  1332.                  * of the bigger interval.
  1333.                  */
  1334.                 leaf->value[leaf->keys - 1] -= count;
  1335.                 return 1;
  1336.             } else if (page + count*PAGE_SIZE < left_pg + left_cnt*PAGE_SIZE) {
  1337.                 count_t new_cnt;
  1338.                
  1339.                 /*
  1340.                  * The interval is contained in the rightmost interval
  1341.                  * of the leaf but its removal requires both updating
  1342.                  * the size of the original interval and
  1343.                  * also inserting a new interval.
  1344.                  */
  1345.                 new_cnt = ((left_pg + left_cnt*PAGE_SIZE) - (page + count*PAGE_SIZE)) >> PAGE_WIDTH;
  1346.                 leaf->value[leaf->keys - 1] -= count + new_cnt;
  1347.                 btree_insert(&a->used_space, page + count*PAGE_SIZE, (void *) new_cnt, leaf);
  1348.                 return 1;
  1349.             }
  1350.         }
  1351.         return 0;
  1352.     }  
  1353.    
  1354.     /*
  1355.      * The border cases have been already resolved.
  1356.      * Now the interval can be only between intervals of the leaf.
  1357.      */
  1358.     for (i = 1; i < leaf->keys - 1; i++) {
  1359.         if (page < leaf->key[i]) {
  1360.             __address left_pg = leaf->key[i - 1];
  1361.             count_t left_cnt = (count_t) leaf->value[i - 1];
  1362.  
  1363.             /*
  1364.              * Now the interval is between intervals corresponding to (i - 1) and i.
  1365.              */
  1366.             if (overlaps(left_pg, left_cnt*PAGE_SIZE, page, count*PAGE_SIZE)) {
  1367.                 if (page + count*PAGE_SIZE == left_pg + left_cnt*PAGE_SIZE) {
  1368.                     /*
  1369.                     * The interval is contained in the interval (i - 1)
  1370.                      * of the leaf and can be removed by updating the size
  1371.                      * of the bigger interval.
  1372.                      */
  1373.                     leaf->value[i - 1] -= count;
  1374.                     return 1;
  1375.                 } else if (page + count*PAGE_SIZE < left_pg + left_cnt*PAGE_SIZE) {
  1376.                     count_t new_cnt;
  1377.                
  1378.                     /*
  1379.                      * The interval is contained in the interval (i - 1)
  1380.                      * of the leaf but its removal requires both updating
  1381.                      * the size of the original interval and
  1382.                      * also inserting a new interval.
  1383.                      */
  1384.                     new_cnt = ((left_pg + left_cnt*PAGE_SIZE) - (page + count*PAGE_SIZE)) >> PAGE_WIDTH;
  1385.                     leaf->value[i - 1] -= count + new_cnt;
  1386.                     btree_insert(&a->used_space, page + count*PAGE_SIZE, (void *) new_cnt, leaf);
  1387.                     return 1;
  1388.                 }
  1389.             }
  1390.             return 0;
  1391.         }
  1392.     }
  1393.  
  1394. error:
  1395.     panic("Inconsistency detected while removing %d pages of used space from %P.\n", count, page);
  1396. }
  1397.  
  1398. /** Remove reference to address space area share info.
  1399.  *
  1400.  * If the reference count drops to 0, the sh_info is deallocated.
  1401.  *
  1402.  * @param sh_info Pointer to address space area share info.
  1403.  */
  1404. void sh_info_remove_reference(share_info_t *sh_info)
  1405. {
  1406.     bool dealloc = false;
  1407.  
  1408.     mutex_lock(&sh_info->lock);
  1409.     ASSERT(sh_info->refcount);
  1410.     if (--sh_info->refcount == 0) {
  1411.         dealloc = true;
  1412.         bool cond;
  1413.        
  1414.         /*
  1415.          * Now walk carefully the pagemap B+tree and free/remove
  1416.          * reference from all frames found there.
  1417.          */
  1418.         for (cond = true; cond;) {
  1419.             btree_node_t *node;
  1420.            
  1421.             ASSERT(!list_empty(&sh_info->pagemap.leaf_head));
  1422.             node = list_get_instance(sh_info->pagemap.leaf_head.next, btree_node_t, leaf_link);
  1423.             if ((cond = node->keys)) {
  1424.                 frame_free(ADDR2PFN((__address) node->value[0]));
  1425.                 btree_remove(&sh_info->pagemap, node->key[0], node);
  1426.             }
  1427.         }
  1428.        
  1429.     }
  1430.     mutex_unlock(&sh_info->lock);
  1431.    
  1432.     if (dealloc) {
  1433.         btree_destroy(&sh_info->pagemap);
  1434.         free(sh_info);
  1435.     }
  1436. }
  1437.  
  1438. /*
  1439.  * Address space related syscalls.
  1440.  */
  1441.  
  1442. /** Wrapper for as_area_create(). */
  1443. __native sys_as_area_create(__address address, size_t size, int flags)
  1444. {
  1445.     if (as_area_create(AS, flags | AS_AREA_CACHEABLE, size, address, AS_AREA_ATTR_NONE, &anon_backend, NULL))
  1446.         return (__native) address;
  1447.     else
  1448.         return (__native) -1;
  1449. }
  1450.  
  1451. /** Wrapper for as_area_resize. */
  1452. __native sys_as_area_resize(__address address, size_t size, int flags)
  1453. {
  1454.     return (__native) as_area_resize(AS, address, size, 0);
  1455. }
  1456.  
  1457. /** Wrapper for as_area_destroy. */
  1458. __native sys_as_area_destroy(__address address)
  1459. {
  1460.     return (__native) as_area_destroy(AS, address);
  1461. }
  1462.