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  1. /*
  2.  * Copyright (C) 2001-2006 Jakub Jermar
  3.  * All rights reserved.
  4.  *
  5.  * Redistribution and use in source and binary forms, with or without
  6.  * modification, are permitted provided that the following conditions
  7.  * are met:
  8.  *
  9.  * - Redistributions of source code must retain the above copyright
  10.  *   notice, this list of conditions and the following disclaimer.
  11.  * - Redistributions in binary form must reproduce the above copyright
  12.  *   notice, this list of conditions and the following disclaimer in the
  13.  *   documentation and/or other materials provided with the distribution.
  14.  * - The name of the author may not be used to endorse or promote products
  15.  *   derived from this software without specific prior written permission.
  16.  *
  17.  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
  18.  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
  19.  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
  20.  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
  21.  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
  22.  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  23.  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  24.  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  25.  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
  26.  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  27.  */
  28.  
  29. /**
  30.  * @file    as.c
  31.  * @brief   Address space related functions.
  32.  *
  33.  * This file contains address space manipulation functions.
  34.  * Roughly speaking, this is a higher-level client of
  35.  * Virtual Address Translation (VAT) subsystem.
  36.  *
  37.  * Functionality provided by this file allows one to
  38.  * create address space and create, resize and share
  39.  * address space areas.
  40.  *
  41.  * @see page.c
  42.  *
  43.  */
  44.  
  45. #include <mm/as.h>
  46. #include <arch/mm/as.h>
  47. #include <mm/page.h>
  48. #include <mm/frame.h>
  49. #include <mm/slab.h>
  50. #include <mm/tlb.h>
  51. #include <arch/mm/page.h>
  52. #include <genarch/mm/page_pt.h>
  53. #include <genarch/mm/page_ht.h>
  54. #include <mm/asid.h>
  55. #include <arch/mm/asid.h>
  56. #include <synch/spinlock.h>
  57. #include <synch/mutex.h>
  58. #include <adt/list.h>
  59. #include <adt/btree.h>
  60. #include <proc/task.h>
  61. #include <proc/thread.h>
  62. #include <arch/asm.h>
  63. #include <panic.h>
  64. #include <debug.h>
  65. #include <print.h>
  66. #include <memstr.h>
  67. #include <macros.h>
  68. #include <arch.h>
  69. #include <errno.h>
  70. #include <config.h>
  71. #include <align.h>
  72. #include <arch/types.h>
  73. #include <typedefs.h>
  74. #include <syscall/copy.h>
  75. #include <arch/interrupt.h>
  76.  
  77. as_operations_t *as_operations = NULL;
  78.  
  79. /** Address space lock. It protects inactive_as_with_asid_head. Must be acquired before as_t mutex. */
  80. SPINLOCK_INITIALIZE(as_lock);
  81.  
  82. /**
  83.  * This list contains address spaces that are not active on any
  84.  * processor and that have valid ASID.
  85.  */
  86. LIST_INITIALIZE(inactive_as_with_asid_head);
  87.  
  88. /** Kernel address space. */
  89. as_t *AS_KERNEL = NULL;
  90.  
  91. static int area_flags_to_page_flags(int aflags);
  92. static int get_area_flags(as_area_t *a);
  93. static as_area_t *find_area_and_lock(as_t *as, __address va);
  94. static bool check_area_conflicts(as_t *as, __address va, size_t size, as_area_t *avoid_area);
  95. int used_space_insert(as_area_t *a, __address page, count_t count);
  96. int used_space_remove(as_area_t *a, __address page, count_t count);
  97.  
  98. /** Initialize address space subsystem. */
  99. void as_init(void)
  100. {
  101.     as_arch_init();
  102.     AS_KERNEL = as_create(FLAG_AS_KERNEL);
  103.     if (!AS_KERNEL)
  104.         panic("can't create kernel address space\n");
  105.    
  106. }
  107.  
  108. /** Create address space.
  109.  *
  110.  * @param flags Flags that influence way in wich the address space is created.
  111.  */
  112. as_t *as_create(int flags)
  113. {
  114.     as_t *as;
  115.  
  116.     as = (as_t *) malloc(sizeof(as_t), 0);
  117.     link_initialize(&as->inactive_as_with_asid_link);
  118.     mutex_initialize(&as->lock);
  119.     btree_create(&as->as_area_btree);
  120.    
  121.     if (flags & FLAG_AS_KERNEL)
  122.         as->asid = ASID_KERNEL;
  123.     else
  124.         as->asid = ASID_INVALID;
  125.    
  126.     as->refcount = 0;
  127.     as->page_table = page_table_create(flags);
  128.  
  129.     return as;
  130. }
  131.  
  132. /** Free Adress space */
  133. void as_free(as_t *as)
  134. {
  135.     ASSERT(as->refcount == 0);
  136.  
  137.     /* TODO: free as_areas and other resources held by as */
  138.     /* TODO: free page table */
  139.     free(as);
  140. }
  141.  
  142. /** Create address space area of common attributes.
  143.  *
  144.  * The created address space area is added to the target address space.
  145.  *
  146.  * @param as Target address space.
  147.  * @param flags Flags of the area memory.
  148.  * @param size Size of area.
  149.  * @param base Base address of area.
  150.  * @param attrs Attributes of the area.
  151.  *
  152.  * @return Address space area on success or NULL on failure.
  153.  */
  154. as_area_t *as_area_create(as_t *as, int flags, size_t size, __address base, int attrs)
  155. {
  156.     ipl_t ipl;
  157.     as_area_t *a;
  158.    
  159.     if (base % PAGE_SIZE)
  160.         return NULL;
  161.  
  162.     if (!size)
  163.         return NULL;
  164.  
  165.     /* Writeable executable areas are not supported. */
  166.     if ((flags & AS_AREA_EXEC) && (flags & AS_AREA_WRITE))
  167.         return NULL;
  168.    
  169.     ipl = interrupts_disable();
  170.     mutex_lock(&as->lock);
  171.    
  172.     if (!check_area_conflicts(as, base, size, NULL)) {
  173.         mutex_unlock(&as->lock);
  174.         interrupts_restore(ipl);
  175.         return NULL;
  176.     }
  177.    
  178.     a = (as_area_t *) malloc(sizeof(as_area_t), 0);
  179.  
  180.     mutex_initialize(&a->lock);
  181.    
  182.     a->flags = flags;
  183.     a->attributes = attrs;
  184.     a->pages = SIZE2FRAMES(size);
  185.     a->base = base;
  186.     btree_create(&a->used_space);
  187.    
  188.     btree_insert(&as->as_area_btree, base, (void *) a, NULL);
  189.  
  190.     mutex_unlock(&as->lock);
  191.     interrupts_restore(ipl);
  192.  
  193.     return a;
  194. }
  195.  
  196. /** Find address space area and change it.
  197.  *
  198.  * @param as Address space.
  199.  * @param address Virtual address belonging to the area to be changed. Must be page-aligned.
  200.  * @param size New size of the virtual memory block starting at address.
  201.  * @param flags Flags influencing the remap operation. Currently unused.
  202.  *
  203.  * @return Zero on success or a value from @ref errno.h otherwise.
  204.  */
  205. int as_area_resize(as_t *as, __address address, size_t size, int flags)
  206. {
  207.     as_area_t *area;
  208.     ipl_t ipl;
  209.     size_t pages;
  210.    
  211.     ipl = interrupts_disable();
  212.     mutex_lock(&as->lock);
  213.    
  214.     /*
  215.      * Locate the area.
  216.      */
  217.     area = find_area_and_lock(as, address);
  218.     if (!area) {
  219.         mutex_unlock(&as->lock);
  220.         interrupts_restore(ipl);
  221.         return ENOENT;
  222.     }
  223.  
  224.     if (area->flags & AS_AREA_DEVICE) {
  225.         /*
  226.          * Remapping of address space areas associated
  227.          * with memory mapped devices is not supported.
  228.          */
  229.         mutex_unlock(&area->lock);
  230.         mutex_unlock(&as->lock);
  231.         interrupts_restore(ipl);
  232.         return ENOTSUP;
  233.     }
  234.  
  235.     pages = SIZE2FRAMES((address - area->base) + size);
  236.     if (!pages) {
  237.         /*
  238.          * Zero size address space areas are not allowed.
  239.          */
  240.         mutex_unlock(&area->lock);
  241.         mutex_unlock(&as->lock);
  242.         interrupts_restore(ipl);
  243.         return EPERM;
  244.     }
  245.    
  246.     if (pages < area->pages) {
  247.         int i;
  248.  
  249.         /*
  250.          * Shrinking the area.
  251.          * No need to check for overlaps.
  252.          */
  253.         for (i = pages; i < area->pages; i++) {
  254.             pte_t *pte;
  255.            
  256.             /*
  257.              * Releasing physical memory.
  258.              * This depends on the fact that the memory was allocated using frame_alloc().
  259.              */
  260.             page_table_lock(as, false);
  261.             pte = page_mapping_find(as, area->base + i*PAGE_SIZE);
  262.             if (pte && PTE_VALID(pte)) {
  263.                 __address frame;
  264.  
  265.                 ASSERT(PTE_PRESENT(pte));
  266.                 frame = PTE_GET_FRAME(pte);
  267.                 page_mapping_remove(as, area->base + i*PAGE_SIZE);
  268.                 page_table_unlock(as, false);
  269.  
  270.                 frame_free(ADDR2PFN(frame));
  271.             } else {
  272.                 page_table_unlock(as, false);
  273.             }
  274.         }
  275.         /*
  276.          * Invalidate TLB's.
  277.          */
  278.         tlb_shootdown_start(TLB_INVL_PAGES, AS->asid, area->base + pages*PAGE_SIZE, area->pages - pages);
  279.         tlb_invalidate_pages(AS->asid, area->base + pages*PAGE_SIZE, area->pages - pages);
  280.         tlb_shootdown_finalize();
  281.     } else {
  282.         /*
  283.          * Growing the area.
  284.          * Check for overlaps with other address space areas.
  285.          */
  286.         if (!check_area_conflicts(as, address, pages * PAGE_SIZE, area)) {
  287.             mutex_unlock(&area->lock);
  288.             mutex_unlock(&as->lock);       
  289.             interrupts_restore(ipl);
  290.             return EADDRNOTAVAIL;
  291.         }
  292.     }
  293.  
  294.     area->pages = pages;
  295.    
  296.     mutex_unlock(&area->lock);
  297.     mutex_unlock(&as->lock);
  298.     interrupts_restore(ipl);
  299.  
  300.     return 0;
  301. }
  302.  
  303. /** Destroy address space area.
  304.  *
  305.  * @param as Address space.
  306.  * @param address Address withing the area to be deleted.
  307.  *
  308.  * @return Zero on success or a value from @ref errno.h on failure.
  309.  */
  310. int as_area_destroy(as_t *as, __address address)
  311. {
  312.     as_area_t *area;
  313.     __address base;
  314.     ipl_t ipl;
  315.     int i;
  316.  
  317.     ipl = interrupts_disable();
  318.     mutex_lock(&as->lock);
  319.  
  320.     area = find_area_and_lock(as, address);
  321.     if (!area) {
  322.         mutex_unlock(&as->lock);
  323.         interrupts_restore(ipl);
  324.         return ENOENT;
  325.     }
  326.  
  327.     base = area->base; 
  328.     for (i = 0; i < area->pages; i++) {
  329.         pte_t *pte;
  330.  
  331.         /*
  332.          * Releasing physical memory.
  333.          * Areas mapping memory-mapped devices are treated differently than
  334.          * areas backing frame_alloc()'ed memory.
  335.          */
  336.         page_table_lock(as, false);
  337.         pte = page_mapping_find(as, area->base + i*PAGE_SIZE);
  338.         if (pte && PTE_VALID(pte)) {
  339.             ASSERT(PTE_PRESENT(pte));
  340.             page_mapping_remove(as, area->base + i*PAGE_SIZE);
  341.             if (area->flags & AS_AREA_DEVICE) {
  342.                 __address frame;
  343.                 frame = PTE_GET_FRAME(pte);
  344.                 frame_free(ADDR2PFN(frame));
  345.             }
  346.             page_table_unlock(as, false);
  347.         } else {
  348.             page_table_unlock(as, false);
  349.         }
  350.     }
  351.     /*
  352.      * Invalidate TLB's.
  353.      */
  354.     tlb_shootdown_start(TLB_INVL_PAGES, AS->asid, area->base, area->pages);
  355.     tlb_invalidate_pages(AS->asid, area->base, area->pages);
  356.     tlb_shootdown_finalize();
  357.  
  358.     area->attributes |= AS_AREA_ATTR_PARTIAL;
  359.     mutex_unlock(&area->lock);
  360.  
  361.     /*
  362.      * Remove the empty area from address space.
  363.      */
  364.     btree_remove(&AS->as_area_btree, base, NULL);
  365.    
  366.     free(area);
  367.    
  368.     mutex_unlock(&AS->lock);
  369.     interrupts_restore(ipl);
  370.     return 0;
  371. }
  372.  
  373. /** Steal address space area from another task.
  374.  *
  375.  * Address space area is stolen from another task
  376.  * Moreover, any existing mapping
  377.  * is copied as well, providing thus a mechanism
  378.  * for sharing group of pages. The source address
  379.  * space area and any associated mapping is preserved.
  380.  *
  381.  * @param src_task Pointer of source task
  382.  * @param src_base Base address of the source address space area.
  383.  * @param acc_size Expected size of the source area
  384.  * @param dst_base Target base address
  385.  *
  386.  * @return Zero on success or ENOENT if there is no such task or
  387.  *     if there is no such address space area,
  388.  *     EPERM if there was a problem in accepting the area or
  389.  *     ENOMEM if there was a problem in allocating destination
  390.  *     address space area.
  391.  */
  392. int as_area_steal(task_t *src_task, __address src_base, size_t acc_size,
  393.           __address dst_base)
  394. {
  395.     ipl_t ipl;
  396.     count_t i;
  397.     as_t *src_as;      
  398.     int src_flags;
  399.     size_t src_size;
  400.     as_area_t *src_area, *dst_area;
  401.  
  402.     ipl = interrupts_disable();
  403.     spinlock_lock(&src_task->lock);
  404.     src_as = src_task->as;
  405.    
  406.     mutex_lock(&src_as->lock);
  407.     src_area = find_area_and_lock(src_as, src_base);
  408.     if (!src_area) {
  409.         /*
  410.          * Could not find the source address space area.
  411.          */
  412.         spinlock_unlock(&src_task->lock);
  413.         mutex_unlock(&src_as->lock);
  414.         interrupts_restore(ipl);
  415.         return ENOENT;
  416.     }
  417.     src_size = src_area->pages * PAGE_SIZE;
  418.     src_flags = src_area->flags;
  419.     mutex_unlock(&src_area->lock);
  420.     mutex_unlock(&src_as->lock);
  421.  
  422.  
  423.     if (src_size != acc_size) {
  424.         spinlock_unlock(&src_task->lock);
  425.         interrupts_restore(ipl);
  426.         return EPERM;
  427.     }
  428.     /*
  429.      * Create copy of the source address space area.
  430.      * The destination area is created with AS_AREA_ATTR_PARTIAL
  431.      * attribute set which prevents race condition with
  432.      * preliminary as_page_fault() calls.
  433.      */
  434.     dst_area = as_area_create(AS, src_flags, src_size, dst_base, AS_AREA_ATTR_PARTIAL);
  435.     if (!dst_area) {
  436.         /*
  437.          * Destination address space area could not be created.
  438.          */
  439.         spinlock_unlock(&src_task->lock);
  440.         interrupts_restore(ipl);
  441.         return ENOMEM;
  442.     }
  443.    
  444.     spinlock_unlock(&src_task->lock);
  445.    
  446.     /*
  447.      * Avoid deadlock by first locking the address space with lower address.
  448.      */
  449.     if (AS < src_as) {
  450.         mutex_lock(&AS->lock);
  451.         mutex_lock(&src_as->lock);
  452.     } else {
  453.         mutex_lock(&AS->lock);
  454.         mutex_lock(&src_as->lock);
  455.     }
  456.    
  457.     for (i = 0; i < SIZE2FRAMES(src_size); i++) {
  458.         pte_t *pte;
  459.         __address frame;
  460.            
  461.         page_table_lock(src_as, false);
  462.         pte = page_mapping_find(src_as, src_base + i*PAGE_SIZE);
  463.         if (pte && PTE_VALID(pte)) {
  464.             ASSERT(PTE_PRESENT(pte));
  465.             frame = PTE_GET_FRAME(pte);
  466.             if (!(src_flags & AS_AREA_DEVICE))
  467.                 frame_reference_add(ADDR2PFN(frame));
  468.             page_table_unlock(src_as, false);
  469.         } else {
  470.             page_table_unlock(src_as, false);
  471.             continue;
  472.         }
  473.        
  474.         page_table_lock(AS, false);
  475.         page_mapping_insert(AS, dst_base + i*PAGE_SIZE, frame, area_flags_to_page_flags(src_flags));
  476.         page_table_unlock(AS, false);
  477.     }
  478.  
  479.     /*
  480.      * Now the destination address space area has been
  481.      * fully initialized. Clear the AS_AREA_ATTR_PARTIAL
  482.      * attribute.
  483.      */
  484.     mutex_lock(&dst_area->lock);
  485.     dst_area->attributes &= ~AS_AREA_ATTR_PARTIAL;
  486.     mutex_unlock(&dst_area->lock);
  487.    
  488.     mutex_unlock(&AS->lock);
  489.     mutex_unlock(&src_as->lock);
  490.     interrupts_restore(ipl);
  491.    
  492.     return 0;
  493. }
  494.  
  495. /** Initialize mapping for one page of address space.
  496.  *
  497.  * This functions maps 'page' to 'frame' according
  498.  * to attributes of the address space area to
  499.  * wich 'page' belongs.
  500.  *
  501.  * @param as Target address space.
  502.  * @param page Virtual page within the area.
  503.  * @param frame Physical frame to which page will be mapped.
  504.  */
  505. void as_set_mapping(as_t *as, __address page, __address frame)
  506. {
  507.     as_area_t *area;
  508.     ipl_t ipl;
  509.    
  510.     ipl = interrupts_disable();
  511.     page_table_lock(as, true);
  512.    
  513.     area = find_area_and_lock(as, page);
  514.     if (!area) {
  515.         panic("page not part of any as_area\n");
  516.     }
  517.  
  518.     page_mapping_insert(as, page, frame, get_area_flags(area));
  519.    
  520.     mutex_unlock(&area->lock);
  521.     page_table_unlock(as, true);
  522.     interrupts_restore(ipl);
  523. }
  524.  
  525. /** Handle page fault within the current address space.
  526.  *
  527.  * This is the high-level page fault handler.
  528.  * Interrupts are assumed disabled.
  529.  *
  530.  * @param page Faulting page.
  531.  * @param istate Pointer to interrupted state.
  532.  *
  533.  * @return 0 on page fault, 1 on success or 2 if the fault was caused by copy_to_uspace() or copy_from_uspace().
  534.  */
  535. int as_page_fault(__address page, istate_t *istate)
  536. {
  537.     pte_t *pte;
  538.     as_area_t *area;
  539.     __address frame;
  540.    
  541.     if (!THREAD)
  542.         return 0;
  543.        
  544.     ASSERT(AS);
  545.  
  546.     mutex_lock(&AS->lock);
  547.     area = find_area_and_lock(AS, page);   
  548.     if (!area) {
  549.         /*
  550.          * No area contained mapping for 'page'.
  551.          * Signal page fault to low-level handler.
  552.          */
  553.         mutex_unlock(&AS->lock);
  554.         goto page_fault;
  555.     }
  556.  
  557.     if (area->attributes & AS_AREA_ATTR_PARTIAL) {
  558.         /*
  559.          * The address space area is not fully initialized.
  560.          * Avoid possible race by returning error.
  561.          */
  562.         mutex_unlock(&area->lock);
  563.         mutex_unlock(&AS->lock);
  564.         goto page_fault;       
  565.     }
  566.  
  567.     ASSERT(!(area->flags & AS_AREA_DEVICE));
  568.  
  569.     page_table_lock(AS, false);
  570.    
  571.     /*
  572.      * To avoid race condition between two page faults
  573.      * on the same address, we need to make sure
  574.      * the mapping has not been already inserted.
  575.      */
  576.     if ((pte = page_mapping_find(AS, page))) {
  577.         if (PTE_PRESENT(pte)) {
  578.             page_table_unlock(AS, false);
  579.             mutex_unlock(&area->lock);
  580.             mutex_unlock(&AS->lock);
  581.             return 1;
  582.         }
  583.     }
  584.  
  585.     /*
  586.      * In general, there can be several reasons that
  587.      * can have caused this fault.
  588.      *
  589.      * - non-existent mapping: the area is a scratch
  590.      *   area (e.g. stack) and so far has not been
  591.      *   allocated a frame for the faulting page
  592.      *
  593.      * - non-present mapping: another possibility,
  594.      *   currently not implemented, would be frame
  595.      *   reuse; when this becomes a possibility,
  596.      *   do not forget to distinguish between
  597.      *   the different causes
  598.      */
  599.     frame = PFN2ADDR(frame_alloc(ONE_FRAME, 0));
  600.     memsetb(PA2KA(frame), FRAME_SIZE, 0);
  601.    
  602.     /*
  603.      * Map 'page' to 'frame'.
  604.      * Note that TLB shootdown is not attempted as only new information is being
  605.      * inserted into page tables.
  606.      */
  607.     page_mapping_insert(AS, page, frame, get_area_flags(area));
  608.     page_table_unlock(AS, false);
  609.    
  610.     mutex_unlock(&area->lock);
  611.     mutex_unlock(&AS->lock);
  612.     return AS_PF_OK;
  613.  
  614. page_fault:
  615.     if (!THREAD)
  616.         return AS_PF_FAULT;
  617.    
  618.     if (THREAD->in_copy_from_uspace) {
  619.         THREAD->in_copy_from_uspace = false;
  620.         istate_set_retaddr(istate, (__address) &memcpy_from_uspace_failover_address);
  621.     } else if (THREAD->in_copy_to_uspace) {
  622.         THREAD->in_copy_to_uspace = false;
  623.         istate_set_retaddr(istate, (__address) &memcpy_to_uspace_failover_address);
  624.     } else {
  625.         return AS_PF_FAULT;
  626.     }
  627.  
  628.     return AS_PF_DEFER;
  629. }
  630.  
  631. /** Switch address spaces.
  632.  *
  633.  * Note that this function cannot sleep as it is essentially a part of
  634.  * the scheduling. Sleeping here would lead to deadlock on wakeup.
  635.  *
  636.  * @param old Old address space or NULL.
  637.  * @param new New address space.
  638.  */
  639. void as_switch(as_t *old, as_t *new)
  640. {
  641.     ipl_t ipl;
  642.     bool needs_asid = false;
  643.    
  644.     ipl = interrupts_disable();
  645.     spinlock_lock(&as_lock);
  646.  
  647.     /*
  648.      * First, take care of the old address space.
  649.      */
  650.     if (old) {
  651.         mutex_lock_active(&old->lock);
  652.         ASSERT(old->refcount);
  653.         if((--old->refcount == 0) && (old != AS_KERNEL)) {
  654.             /*
  655.              * The old address space is no longer active on
  656.              * any processor. It can be appended to the
  657.              * list of inactive address spaces with assigned
  658.              * ASID.
  659.              */
  660.              ASSERT(old->asid != ASID_INVALID);
  661.              list_append(&old->inactive_as_with_asid_link, &inactive_as_with_asid_head);
  662.         }
  663.         mutex_unlock(&old->lock);
  664.     }
  665.  
  666.     /*
  667.      * Second, prepare the new address space.
  668.      */
  669.     mutex_lock_active(&new->lock);
  670.     if ((new->refcount++ == 0) && (new != AS_KERNEL)) {
  671.         if (new->asid != ASID_INVALID)
  672.             list_remove(&new->inactive_as_with_asid_link);
  673.         else
  674.             needs_asid = true;  /* defer call to asid_get() until new->lock is released */
  675.     }
  676.     SET_PTL0_ADDRESS(new->page_table);
  677.     mutex_unlock(&new->lock);
  678.  
  679.     if (needs_asid) {
  680.         /*
  681.          * Allocation of new ASID was deferred
  682.          * until now in order to avoid deadlock.
  683.          */
  684.         asid_t asid;
  685.        
  686.         asid = asid_get();
  687.         mutex_lock_active(&new->lock);
  688.         new->asid = asid;
  689.         mutex_unlock(&new->lock);
  690.     }
  691.     spinlock_unlock(&as_lock);
  692.     interrupts_restore(ipl);
  693.    
  694.     /*
  695.      * Perform architecture-specific steps.
  696.      * (e.g. write ASID to hardware register etc.)
  697.      */
  698.     as_install_arch(new);
  699.    
  700.     AS = new;
  701. }
  702.  
  703. /** Convert address space area flags to page flags.
  704.  *
  705.  * @param aflags Flags of some address space area.
  706.  *
  707.  * @return Flags to be passed to page_mapping_insert().
  708.  */
  709. int area_flags_to_page_flags(int aflags)
  710. {
  711.     int flags;
  712.  
  713.     flags = PAGE_USER | PAGE_PRESENT;
  714.    
  715.     if (aflags & AS_AREA_READ)
  716.         flags |= PAGE_READ;
  717.        
  718.     if (aflags & AS_AREA_WRITE)
  719.         flags |= PAGE_WRITE;
  720.    
  721.     if (aflags & AS_AREA_EXEC)
  722.         flags |= PAGE_EXEC;
  723.    
  724.     if (!(aflags & AS_AREA_DEVICE))
  725.         flags |= PAGE_CACHEABLE;
  726.        
  727.     return flags;
  728. }
  729.  
  730. /** Compute flags for virtual address translation subsytem.
  731.  *
  732.  * The address space area must be locked.
  733.  * Interrupts must be disabled.
  734.  *
  735.  * @param a Address space area.
  736.  *
  737.  * @return Flags to be used in page_mapping_insert().
  738.  */
  739. int get_area_flags(as_area_t *a)
  740. {
  741.     return area_flags_to_page_flags(a->flags);
  742. }
  743.  
  744. /** Create page table.
  745.  *
  746.  * Depending on architecture, create either address space
  747.  * private or global page table.
  748.  *
  749.  * @param flags Flags saying whether the page table is for kernel address space.
  750.  *
  751.  * @return First entry of the page table.
  752.  */
  753. pte_t *page_table_create(int flags)
  754. {
  755.         ASSERT(as_operations);
  756.         ASSERT(as_operations->page_table_create);
  757.  
  758.         return as_operations->page_table_create(flags);
  759. }
  760.  
  761. /** Lock page table.
  762.  *
  763.  * This function should be called before any page_mapping_insert(),
  764.  * page_mapping_remove() and page_mapping_find().
  765.  *
  766.  * Locking order is such that address space areas must be locked
  767.  * prior to this call. Address space can be locked prior to this
  768.  * call in which case the lock argument is false.
  769.  *
  770.  * @param as Address space.
  771.  * @param lock If false, do not attempt to lock as->lock.
  772.  */
  773. void page_table_lock(as_t *as, bool lock)
  774. {
  775.     ASSERT(as_operations);
  776.     ASSERT(as_operations->page_table_lock);
  777.  
  778.     as_operations->page_table_lock(as, lock);
  779. }
  780.  
  781. /** Unlock page table.
  782.  *
  783.  * @param as Address space.
  784.  * @param unlock If false, do not attempt to unlock as->lock.
  785.  */
  786. void page_table_unlock(as_t *as, bool unlock)
  787. {
  788.     ASSERT(as_operations);
  789.     ASSERT(as_operations->page_table_unlock);
  790.  
  791.     as_operations->page_table_unlock(as, unlock);
  792. }
  793.  
  794.  
  795. /** Find address space area and lock it.
  796.  *
  797.  * The address space must be locked and interrupts must be disabled.
  798.  *
  799.  * @param as Address space.
  800.  * @param va Virtual address.
  801.  *
  802.  * @return Locked address space area containing va on success or NULL on failure.
  803.  */
  804. as_area_t *find_area_and_lock(as_t *as, __address va)
  805. {
  806.     as_area_t *a;
  807.     btree_node_t *leaf, *lnode;
  808.     int i;
  809.    
  810.     a = (as_area_t *) btree_search(&as->as_area_btree, va, &leaf);
  811.     if (a) {
  812.         /* va is the base address of an address space area */
  813.         mutex_lock(&a->lock);
  814.         return a;
  815.     }
  816.    
  817.     /*
  818.      * Search the leaf node and the righmost record of its left neighbour
  819.      * to find out whether this is a miss or va belongs to an address
  820.      * space area found there.
  821.      */
  822.    
  823.     /* First, search the leaf node itself. */
  824.     for (i = 0; i < leaf->keys; i++) {
  825.         a = (as_area_t *) leaf->value[i];
  826.         mutex_lock(&a->lock);
  827.         if ((a->base <= va) && (va < a->base + a->pages * PAGE_SIZE)) {
  828.             return a;
  829.         }
  830.         mutex_unlock(&a->lock);
  831.     }
  832.  
  833.     /*
  834.      * Second, locate the left neighbour and test its last record.
  835.      * Because of its position in the B+tree, it must have base < va.
  836.      */
  837.     if ((lnode = btree_leaf_node_left_neighbour(&as->as_area_btree, leaf))) {
  838.         a = (as_area_t *) lnode->value[lnode->keys - 1];
  839.         mutex_lock(&a->lock);
  840.         if (va < a->base + a->pages * PAGE_SIZE) {
  841.             return a;
  842.         }
  843.         mutex_unlock(&a->lock);
  844.     }
  845.  
  846.     return NULL;
  847. }
  848.  
  849. /** Check area conflicts with other areas.
  850.  *
  851.  * The address space must be locked and interrupts must be disabled.
  852.  *
  853.  * @param as Address space.
  854.  * @param va Starting virtual address of the area being tested.
  855.  * @param size Size of the area being tested.
  856.  * @param avoid_area Do not touch this area.
  857.  *
  858.  * @return True if there is no conflict, false otherwise.
  859.  */
  860. bool check_area_conflicts(as_t *as, __address va, size_t size, as_area_t *avoid_area)
  861. {
  862.     as_area_t *a;
  863.     btree_node_t *leaf, *node;
  864.     int i;
  865.    
  866.     /*
  867.      * We don't want any area to have conflicts with NULL page.
  868.      */
  869.     if (overlaps(va, size, NULL, PAGE_SIZE))
  870.         return false;
  871.    
  872.     /*
  873.      * The leaf node is found in O(log n), where n is proportional to
  874.      * the number of address space areas belonging to as.
  875.      * The check for conflicts is then attempted on the rightmost
  876.      * record in the left neighbour, the leftmost record in the right
  877.      * neighbour and all records in the leaf node itself.
  878.      */
  879.    
  880.     if ((a = (as_area_t *) btree_search(&as->as_area_btree, va, &leaf))) {
  881.         if (a != avoid_area)
  882.             return false;
  883.     }
  884.    
  885.     /* First, check the two border cases. */
  886.     if ((node = btree_leaf_node_left_neighbour(&as->as_area_btree, leaf))) {
  887.         a = (as_area_t *) node->value[node->keys - 1];
  888.         mutex_lock(&a->lock);
  889.         if (overlaps(va, size, a->base, a->pages * PAGE_SIZE)) {
  890.             mutex_unlock(&a->lock);
  891.             return false;
  892.         }
  893.         mutex_unlock(&a->lock);
  894.     }
  895.     if ((node = btree_leaf_node_right_neighbour(&as->as_area_btree, leaf))) {
  896.         a = (as_area_t *) node->value[0];
  897.         mutex_lock(&a->lock);
  898.         if (overlaps(va, size, a->base, a->pages * PAGE_SIZE)) {
  899.             mutex_unlock(&a->lock);
  900.             return false;
  901.         }
  902.         mutex_unlock(&a->lock);
  903.     }
  904.    
  905.     /* Second, check the leaf node. */
  906.     for (i = 0; i < leaf->keys; i++) {
  907.         a = (as_area_t *) leaf->value[i];
  908.    
  909.         if (a == avoid_area)
  910.             continue;
  911.    
  912.         mutex_lock(&a->lock);
  913.         if (overlaps(va, size, a->base, a->pages * PAGE_SIZE)) {
  914.             mutex_unlock(&a->lock);
  915.             return false;
  916.         }
  917.         mutex_unlock(&a->lock);
  918.     }
  919.  
  920.     /*
  921.      * So far, the area does not conflict with other areas.
  922.      * Check if it doesn't conflict with kernel address space.
  923.      */  
  924.     if (!KERNEL_ADDRESS_SPACE_SHADOWED) {
  925.         return !overlaps(va, size,
  926.             KERNEL_ADDRESS_SPACE_START, KERNEL_ADDRESS_SPACE_END-KERNEL_ADDRESS_SPACE_START);
  927.     }
  928.  
  929.     return true;
  930. }
  931.  
  932. /** Return size of the address space area with given base.  */
  933. size_t as_get_size(__address base)
  934. {
  935.     ipl_t ipl;
  936.     as_area_t *src_area;
  937.     size_t size;
  938.  
  939.     ipl = interrupts_disable();
  940.     src_area = find_area_and_lock(AS, base);
  941.     if (src_area){
  942.         size = src_area->pages * PAGE_SIZE;
  943.         mutex_unlock(&src_area->lock);
  944.     } else {
  945.         size = 0;
  946.     }
  947.     interrupts_restore(ipl);
  948.     return size;
  949. }
  950.  
  951. /** Mark portion of address space area as used.
  952.  *
  953.  * The address space area must be already locked.
  954.  *
  955.  * @param a Address space area.
  956.  * @param page First page to be marked.
  957.  * @param count Number of page to be marked.
  958.  *
  959.  * @return 0 on failure and 1 on success.
  960.  */
  961. int used_space_insert(as_area_t *a, __address page, count_t count)
  962. {
  963.     btree_node_t *leaf, *node;
  964.     count_t pages;
  965.     int i;
  966.  
  967.     ASSERT(page == ALIGN_DOWN(page, PAGE_SIZE));
  968.     ASSERT(count);
  969.  
  970.     pages = (count_t) btree_search(&a->used_space, page, &leaf);
  971.     if (pages) {
  972.         /*
  973.          * We hit the beginning of some used space.
  974.          */
  975.         return 0;
  976.     }
  977.  
  978.     node = btree_leaf_node_left_neighbour(&a->used_space, leaf);
  979.     if (node) {
  980.         __address left_pg = node->key[node->keys - 1], right_pg = leaf->key[0];
  981.         count_t left_cnt = (count_t) node->value[node->keys - 1], right_cnt = (count_t) leaf->value[0];
  982.        
  983.         /*
  984.          * Examine the possibility that the interval fits
  985.          * somewhere between the rightmost interval of
  986.          * the left neigbour and the first interval of the leaf.
  987.          */
  988.          
  989.         if (page >= right_pg) {
  990.             /* Do nothing. */
  991.         } else if (overlaps(page, count*PAGE_SIZE, left_pg, left_cnt*PAGE_SIZE)) {
  992.             /* The interval intersects with the left interval. */
  993.             return 0;
  994.         } else if (overlaps(page, count*PAGE_SIZE, right_pg, right_cnt*PAGE_SIZE)) {
  995.             /* The interval intersects with the right interval. */
  996.             return 0;          
  997.         } else if ((page == left_pg + left_cnt*PAGE_SIZE) && (page + count*PAGE_SIZE == right_pg)) {
  998.             /* The interval can be added by merging the two already present intervals. */
  999.             node->value[node->keys - 1] += (count_t) count + right_cnt;
  1000.             btree_remove(&a->used_space, right_pg, leaf);
  1001.             return 1;
  1002.         } else if (page == left_pg + left_cnt*PAGE_SIZE) {
  1003.             /* The interval can be added by simply growing the left interval. */
  1004.             node->value[node->keys - 1] += (count_t) count;
  1005.             return 1;
  1006.         } else if (page + count*PAGE_SIZE == right_pg) {
  1007.             /*
  1008.              * The interval can be addded by simply moving base of the right
  1009.              * interval down and increasing its size accordingly.
  1010.              */
  1011.             leaf->value[0] += (count_t) count;
  1012.             leaf->key[0] = page;
  1013.             return 1;
  1014.         } else {
  1015.             /*
  1016.              * The interval is between both neigbouring intervals,
  1017.              * but cannot be merged with any of them.
  1018.              */
  1019.             btree_insert(&a->used_space, page, (void *) count, leaf);
  1020.             return 1;
  1021.         }
  1022.     } else if (page < leaf->key[0]) {
  1023.         __address right_pg = leaf->key[0];
  1024.         count_t right_cnt = (count_t) leaf->value[0];
  1025.    
  1026.         /*
  1027.          * Investigate the border case in which the left neighbour does not
  1028.          * exist but the interval fits from the left.
  1029.          */
  1030.          
  1031.         if (overlaps(page, count*PAGE_SIZE, right_pg, right_cnt*PAGE_SIZE)) {
  1032.             /* The interval intersects with the right interval. */
  1033.             return 0;
  1034.         } else if (page + count*PAGE_SIZE == right_pg) {
  1035.             /*
  1036.              * The interval can be added by moving the base of the right interval down
  1037.              * and increasing its size accordingly.
  1038.              */
  1039.             leaf->key[0] = page;
  1040.             leaf->value[0] += (count_t) count;
  1041.             return 1;
  1042.         } else {
  1043.             /*
  1044.              * The interval doesn't adjoin with the right interval.
  1045.              * It must be added individually.
  1046.              */
  1047.             btree_insert(&a->used_space, page, (void *) count, leaf);
  1048.             return 1;
  1049.         }
  1050.     }
  1051.  
  1052.     node = btree_leaf_node_right_neighbour(&a->used_space, leaf);
  1053.     if (node) {
  1054.         __address left_pg = leaf->key[leaf->keys - 1], right_pg = node->key[0];
  1055.         count_t left_cnt = (count_t) leaf->value[leaf->keys - 1], right_cnt = (count_t) node->value[0];
  1056.        
  1057.         /*
  1058.          * Examine the possibility that the interval fits
  1059.          * somewhere between the leftmost interval of
  1060.          * the right neigbour and the last interval of the leaf.
  1061.          */
  1062.  
  1063.         if (page < left_pg) {
  1064.             /* Do nothing. */
  1065.         } else if (overlaps(page, count*PAGE_SIZE, left_pg, left_cnt*PAGE_SIZE)) {
  1066.             /* The interval intersects with the left interval. */
  1067.             return 0;
  1068.         } else if (overlaps(page, count*PAGE_SIZE, right_pg, right_cnt*PAGE_SIZE)) {
  1069.             /* The interval intersects with the right interval. */
  1070.             return 0;          
  1071.         } else if ((page == left_pg + left_cnt*PAGE_SIZE) && (page + count*PAGE_SIZE == right_pg)) {
  1072.             /* The interval can be added by merging the two already present intervals. */
  1073.             leaf->value[leaf->keys - 1] += (count_t) count + right_cnt;
  1074.             btree_remove(&a->used_space, right_pg, node);
  1075.             return 1;
  1076.         } else if (page == left_pg + left_cnt*PAGE_SIZE) {
  1077.             /* The interval can be added by simply growing the left interval. */
  1078.             leaf->value[leaf->keys - 1] += (count_t) count;
  1079.             return 1;
  1080.         } else if (page + count*PAGE_SIZE == right_pg) {
  1081.             /*
  1082.              * The interval can be addded by simply moving base of the right
  1083.              * interval down and increasing its size accordingly.
  1084.              */
  1085.             node->value[0] += (count_t) count;
  1086.             node->key[0] = page;
  1087.             return 1;
  1088.         } else {
  1089.             /*
  1090.              * The interval is between both neigbouring intervals,
  1091.              * but cannot be merged with any of them.
  1092.              */
  1093.             btree_insert(&a->used_space, page, (void *) count, leaf);
  1094.             return 1;
  1095.         }
  1096.     } else if (page >= leaf->key[leaf->keys - 1]) {
  1097.         __address left_pg = leaf->key[leaf->keys - 1];
  1098.         count_t left_cnt = (count_t) leaf->value[leaf->keys - 1];
  1099.    
  1100.         /*
  1101.          * Investigate the border case in which the right neighbour does not
  1102.          * exist but the interval fits from the right.
  1103.          */
  1104.          
  1105.         if (overlaps(page, count*PAGE_SIZE, left_pg, left_cnt*PAGE_SIZE)) {
  1106.             /* The interval intersects with the right interval. */
  1107.             return 0;
  1108.         } else if (left_pg + left_cnt*PAGE_SIZE == page) {
  1109.             /* The interval can be added by growing the left interval. */
  1110.             leaf->value[leaf->keys - 1] += (count_t) count;
  1111.             return 1;
  1112.         } else {
  1113.             /*
  1114.              * The interval doesn't adjoin with the left interval.
  1115.              * It must be added individually.
  1116.              */
  1117.             btree_insert(&a->used_space, page, (void *) count, leaf);
  1118.             return 1;
  1119.         }
  1120.     }
  1121.    
  1122.     /*
  1123.      * Note that if the algorithm made it thus far, the interval can fit only
  1124.      * between two other intervals of the leaf. The two border cases were already
  1125.      * resolved.
  1126.      */
  1127.     for (i = 1; i < leaf->keys; i++) {
  1128.         if (page < leaf->key[i]) {
  1129.             __address left_pg = leaf->key[i - 1], right_pg = leaf->key[i];
  1130.             count_t left_cnt = (count_t) leaf->value[i - 1], right_cnt = (count_t) leaf->value[i];
  1131.  
  1132.             /*
  1133.              * The interval fits between left_pg and right_pg.
  1134.              */
  1135.  
  1136.             if (overlaps(page, count*PAGE_SIZE, left_pg, left_cnt*PAGE_SIZE)) {
  1137.                 /* The interval intersects with the left interval. */
  1138.                 return 0;
  1139.             } else if (overlaps(page, count*PAGE_SIZE, right_pg, right_cnt*PAGE_SIZE)) {
  1140.                 /* The interval intersects with the right interval. */
  1141.                 return 0;          
  1142.             } else if ((page == left_pg + left_cnt*PAGE_SIZE) && (page + count*PAGE_SIZE == right_pg)) {
  1143.                 /* The interval can be added by merging the two already present intervals. */
  1144.                 leaf->value[i - 1] += (count_t) count + right_cnt;
  1145.                 btree_remove(&a->used_space, right_pg, leaf);
  1146.                 return 1;
  1147.             } else if (page == left_pg + left_cnt*PAGE_SIZE) {
  1148.                 /* The interval can be added by simply growing the left interval. */
  1149.                 leaf->value[i - 1] += (count_t) count;
  1150.                 return 1;
  1151.             } else if (page + count*PAGE_SIZE == right_pg) {
  1152.                 /*
  1153.                      * The interval can be addded by simply moving base of the right
  1154.                  * interval down and increasing its size accordingly.
  1155.                  */
  1156.                 leaf->value[i] += (count_t) count;
  1157.                 leaf->key[i] = page;
  1158.                 return 1;
  1159.             } else {
  1160.                 /*
  1161.                  * The interval is between both neigbouring intervals,
  1162.                  * but cannot be merged with any of them.
  1163.                  */
  1164.                 btree_insert(&a->used_space, page, (void *) count, leaf);
  1165.                 return 1;
  1166.             }
  1167.         }
  1168.     }
  1169.  
  1170.     panic("Inconsistency detected while adding %d pages of used space at %P.\n", count, page);
  1171. }
  1172.  
  1173. /** Mark portion of address space area as unused.
  1174.  *
  1175.  * The address space area must be already locked.
  1176.  *
  1177.  * @param a Address space area.
  1178.  * @param page First page to be marked.
  1179.  * @param count Number of page to be marked.
  1180.  *
  1181.  * @return 0 on failure and 1 on success.
  1182.  */
  1183. int used_space_remove(as_area_t *a, __address page, count_t count)
  1184. {
  1185.     btree_node_t *leaf, *node;
  1186.     count_t pages;
  1187.     int i;
  1188.  
  1189.     ASSERT(page == ALIGN_DOWN(page, PAGE_SIZE));
  1190.     ASSERT(count);
  1191.  
  1192.     pages = (count_t) btree_search(&a->used_space, page, &leaf);
  1193.     if (pages) {
  1194.         /*
  1195.          * We are lucky, page is the beginning of some interval.
  1196.          */
  1197.         if (count > pages) {
  1198.             return 0;
  1199.         } else if (count == pages) {
  1200.             btree_remove(&a->used_space, page, leaf);
  1201.         } else {
  1202.             /*
  1203.              * Find the respective interval.
  1204.              * Decrease its size and relocate its start address.
  1205.              */
  1206.             for (i = 0; i < leaf->keys; i++) {
  1207.                 if (leaf->key[i] == page) {
  1208.                     leaf->key[i] += count*PAGE_SIZE;
  1209.                     leaf->value[i] -= (count_t) count;
  1210.                     return 1;
  1211.                 }
  1212.             }
  1213.             goto error;
  1214.         }
  1215.     }
  1216.  
  1217.     node = btree_leaf_node_left_neighbour(&a->used_space, leaf);
  1218.     if (node && page < leaf->key[0]) {
  1219.         __address left_pg = node->key[node->keys - 1];
  1220.         count_t left_cnt = (count_t) node->value[node->keys - 1];
  1221.  
  1222.         if (overlaps(left_pg, left_cnt*PAGE_SIZE, page, count*PAGE_SIZE)) {
  1223.             if (page + count*PAGE_SIZE == left_pg + left_cnt*PAGE_SIZE) {
  1224.                 /*
  1225.                  * The interval is contained in the rightmost interval
  1226.                  * of the left neighbour and can be removed by
  1227.                  * updating the size of the bigger interval.
  1228.                  */
  1229.                 node->value[node->keys - 1] -= (count_t) count;
  1230.                 return 1;
  1231.             } else if (page + count*PAGE_SIZE < left_pg + left_cnt*PAGE_SIZE) {
  1232.                 count_t new_cnt = (left_pg + left_cnt*PAGE_SIZE) - (page + count*PAGE_SIZE);
  1233.                
  1234.                 /*
  1235.                  * The interval is contained in the rightmost interval
  1236.                  * of the left neighbour but its removal requires
  1237.                  * both updating the size of the original interval and
  1238.                  * also inserting a new interval.
  1239.                  */
  1240.                 node->value[node->keys - 1] -= (count_t) count + new_cnt;
  1241.                 btree_insert(&a->used_space, page + count*PAGE_SIZE, (void *) new_cnt, leaf);
  1242.                 return 1;
  1243.             }
  1244.         }
  1245.         return 0;
  1246.     } else if (page < leaf->key[0]) {
  1247.         return 0;
  1248.     }
  1249.    
  1250.     if (page > leaf->key[leaf->keys - 1]) {
  1251.         __address left_pg = leaf->key[leaf->keys - 1];
  1252.         count_t left_cnt = (count_t) leaf->value[leaf->keys - 1];
  1253.  
  1254.         if (overlaps(left_pg, left_cnt*PAGE_SIZE, page, count*PAGE_SIZE)) {
  1255.             if (page + count*PAGE_SIZE == left_pg + left_cnt*PAGE_SIZE) {
  1256.                 /*
  1257.                  * The interval is contained in the rightmost interval
  1258.                  * of the leaf and can be removed by updating the size
  1259.                  * of the bigger interval.
  1260.                  */
  1261.                 leaf->value[leaf->keys - 1] -= (count_t) count;
  1262.                 return 1;
  1263.             } else if (page + count*PAGE_SIZE < left_pg + left_cnt*PAGE_SIZE) {
  1264.                 count_t new_cnt = (left_pg + left_cnt*PAGE_SIZE) - (page + count*PAGE_SIZE);
  1265.                
  1266.                 /*
  1267.                  * The interval is contained in the rightmost interval
  1268.                  * of the leaf but its removal requires both updating
  1269.                  * the size of the original interval and
  1270.                  * also inserting a new interval.
  1271.                  */
  1272.                 leaf->value[leaf->keys - 1] -= (count_t) count + new_cnt;
  1273.                 btree_insert(&a->used_space, page + count*PAGE_SIZE, (void *) new_cnt, leaf);
  1274.                 return 1;
  1275.             }
  1276.         }
  1277.         return 0;
  1278.     }  
  1279.    
  1280.     /*
  1281.      * The border cases have been already resolved.
  1282.      * Now the interval can be only between intervals of the leaf.
  1283.      */
  1284.     for (i = 1; i < leaf->keys - 1; i++) {
  1285.         if (page < leaf->key[i]) {
  1286.             __address left_pg = leaf->key[i - 1];
  1287.             count_t left_cnt = (count_t) leaf->value[i - 1];
  1288.  
  1289.             /*
  1290.              * Now the interval is between intervals corresponding to (i - 1) and i.
  1291.              */
  1292.             if (overlaps(left_pg, left_cnt*PAGE_SIZE, page, count*PAGE_SIZE)) {
  1293.                 if (page + count*PAGE_SIZE == left_pg + left_cnt*PAGE_SIZE) {
  1294.                     /*
  1295.                     * The interval is contained in the interval (i - 1)
  1296.                      * of the leaf and can be removed by updating the size
  1297.                      * of the bigger interval.
  1298.                      */
  1299.                     leaf->value[i - 1] -= (count_t) count;
  1300.                     return 1;
  1301.                 } else if (page + count*PAGE_SIZE < left_pg + left_cnt*PAGE_SIZE) {
  1302.                     count_t new_cnt = (left_pg + left_cnt*PAGE_SIZE) - (page + count*PAGE_SIZE);
  1303.                
  1304.                     /*
  1305.                      * The interval is contained in the interval (i - 1)
  1306.                      * of the leaf but its removal requires both updating
  1307.                      * the size of the original interval and
  1308.                      * also inserting a new interval.
  1309.                      */
  1310.                     leaf->value[i - 1] -= (count_t) count + new_cnt;
  1311.                     btree_insert(&a->used_space, page + count*PAGE_SIZE, (void *) new_cnt, leaf);
  1312.                     return 1;
  1313.                 }
  1314.             }
  1315.             return 0;
  1316.         }
  1317.     }
  1318.  
  1319. error:
  1320.     panic("Inconsistency detected while removing %d pages of used space from %P.\n", count, page);
  1321. }
  1322.  
  1323. /*
  1324.  * Address space related syscalls.
  1325.  */
  1326.  
  1327. /** Wrapper for as_area_create(). */
  1328. __native sys_as_area_create(__address address, size_t size, int flags)
  1329. {
  1330.     if (as_area_create(AS, flags, size, address, AS_AREA_ATTR_NONE))
  1331.         return (__native) address;
  1332.     else
  1333.         return (__native) -1;
  1334. }
  1335.  
  1336. /** Wrapper for as_area_resize. */
  1337. __native sys_as_area_resize(__address address, size_t size, int flags)
  1338. {
  1339.     return (__native) as_area_resize(AS, address, size, 0);
  1340. }
  1341.  
  1342. /** Wrapper for as_area_destroy. */
  1343. __native sys_as_area_destroy(__address address)
  1344. {
  1345.     return (__native) as_area_destroy(AS, address);
  1346. }
  1347.