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