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