Subversion Repositories HelenOS

Rev

Rev 2009 | Rev 2071 | Go to most recent revision | Blame | Compare with Previous | Last modification | View Log | Download | RSS feed

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