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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 <adt/list.h>
  58. #include <adt/btree.h>
  59. #include <proc/task.h>
  60. #include <arch/asm.h>
  61. #include <panic.h>
  62. #include <debug.h>
  63. #include <print.h>
  64. #include <memstr.h>
  65. #include <macros.h>
  66. #include <arch.h>
  67. #include <errno.h>
  68. #include <config.h>
  69. #include <arch/types.h>
  70. #include <typedefs.h>
  71.  
  72. as_operations_t *as_operations = NULL;
  73.  
  74. /** Address space lock. It protects inactive_as_with_asid_head. */
  75. SPINLOCK_INITIALIZE(as_lock);
  76.  
  77. /**
  78.  * This list contains address spaces that are not active on any
  79.  * processor and that have valid ASID.
  80.  */
  81. LIST_INITIALIZE(inactive_as_with_asid_head);
  82.  
  83. /** Kernel address space. */
  84. as_t *AS_KERNEL = NULL;
  85.  
  86. static int area_flags_to_page_flags(int aflags);
  87. static int get_area_flags(as_area_t *a);
  88. static as_area_t *find_area_and_lock(as_t *as, __address va);
  89. static bool check_area_conflicts(as_t *as, __address va, size_t size, as_area_t *avoid_area);
  90.  
  91. /** Initialize address space subsystem. */
  92. void as_init(void)
  93. {
  94.     as_arch_init();
  95.     AS_KERNEL = as_create(FLAG_AS_KERNEL);
  96.         if (!AS_KERNEL)
  97.                 panic("can't create kernel address space\n");
  98. }
  99.  
  100. /** Create address space.
  101.  *
  102.  * @param flags Flags that influence way in wich the address space is created.
  103.  */
  104. as_t *as_create(int flags)
  105. {
  106.     as_t *as;
  107.  
  108.     as = (as_t *) malloc(sizeof(as_t), 0);
  109.     link_initialize(&as->inactive_as_with_asid_link);
  110.     spinlock_initialize(&as->lock, "as_lock");
  111.     btree_create(&as->as_area_btree);
  112.    
  113.     if (flags & FLAG_AS_KERNEL)
  114.         as->asid = ASID_KERNEL;
  115.     else
  116.         as->asid = ASID_INVALID;
  117.    
  118.     as->refcount = 0;
  119.     as->page_table = page_table_create(flags);
  120.  
  121.     return as;
  122. }
  123.  
  124. /** Free Adress space */
  125. void as_free(as_t *as)
  126. {
  127.     ASSERT(as->refcount == 0);
  128.  
  129.     /* TODO: free as_areas and other resources held by as */
  130.     /* TODO: free page table */
  131.     free(as);
  132. }
  133.  
  134. /** Create address space area of common attributes.
  135.  *
  136.  * The created address space area is added to the target address space.
  137.  *
  138.  * @param as Target address space.
  139.  * @param flags Flags of the area memory.
  140.  * @param size Size of area.
  141.  * @param base Base address of area.
  142.  * @param attrs Attributes of the area.
  143.  *
  144.  * @return Address space area on success or NULL on failure.
  145.  */
  146. as_area_t *as_area_create(as_t *as, int flags, size_t size, __address base, int attrs)
  147. {
  148.     ipl_t ipl;
  149.     as_area_t *a;
  150.    
  151.     if (base % PAGE_SIZE)
  152.         return NULL;
  153.  
  154.     if (!size)
  155.         return NULL;
  156.  
  157.     /* Writeable executable areas are not supported. */
  158.     if ((flags & AS_AREA_EXEC) && (flags & AS_AREA_WRITE))
  159.         return NULL;
  160.    
  161.     ipl = interrupts_disable();
  162.     spinlock_lock(&as->lock);
  163.    
  164.     if (!check_area_conflicts(as, base, size, NULL)) {
  165.         spinlock_unlock(&as->lock);
  166.         interrupts_restore(ipl);
  167.         return NULL;
  168.     }
  169.    
  170.     a = (as_area_t *) malloc(sizeof(as_area_t), 0);
  171.  
  172.     spinlock_initialize(&a->lock, "as_area_lock");
  173.    
  174.     a->flags = flags;
  175.     a->attributes = attrs;
  176.     a->pages = SIZE2FRAMES(size);
  177.     a->base = base;
  178.    
  179.     btree_insert(&as->as_area_btree, base, (void *) a, NULL);
  180.  
  181.     spinlock_unlock(&as->lock);
  182.     interrupts_restore(ipl);
  183.  
  184.     return a;
  185. }
  186.  
  187. /** Find address space area and change it.
  188.  *
  189.  * @param as Address space.
  190.  * @param address Virtual address belonging to the area to be changed. Must be page-aligned.
  191.  * @param size New size of the virtual memory block starting at address.
  192.  * @param flags Flags influencing the remap operation. Currently unused.
  193.  *
  194.  * @return address on success, (__address) -1 otherwise.
  195.  */
  196. __address as_area_resize(as_t *as, __address address, size_t size, int flags)
  197. {
  198.     as_area_t *area = NULL;
  199.     ipl_t ipl;
  200.     size_t pages;
  201.    
  202.     ipl = interrupts_disable();
  203.     spinlock_lock(&as->lock);
  204.    
  205.     /*
  206.      * Locate the area.
  207.      */
  208.     area = find_area_and_lock(as, address);
  209.     if (!area) {
  210.         spinlock_unlock(&as->lock);
  211.         interrupts_restore(ipl);
  212.         return (__address) -1;
  213.     }
  214.  
  215.     if (area->flags & AS_AREA_DEVICE) {
  216.         /*
  217.          * Remapping of address space areas associated
  218.          * with memory mapped devices is not supported.
  219.          */
  220.         spinlock_unlock(&area->lock);
  221.         spinlock_unlock(&as->lock);
  222.         interrupts_restore(ipl);
  223.         return (__address) -1;
  224.     }
  225.  
  226.     pages = SIZE2FRAMES((address - area->base) + size);
  227.     if (!pages) {
  228.         /*
  229.          * Zero size address space areas are not allowed.
  230.          */
  231.         spinlock_unlock(&area->lock);
  232.         spinlock_unlock(&as->lock);
  233.         interrupts_restore(ipl);
  234.         return (__address) -1;
  235.     }
  236.    
  237.     if (pages < area->pages) {
  238.         int i;
  239.  
  240.         /*
  241.          * Shrinking the area.
  242.          * No need to check for overlaps.
  243.          */
  244.         for (i = pages; i < area->pages; i++) {
  245.             pte_t *pte;
  246.            
  247.             /*
  248.              * Releasing physical memory.
  249.              * This depends on the fact that the memory was allocated using frame_alloc().
  250.              */
  251.             page_table_lock(as, false);
  252.             pte = page_mapping_find(as, area->base + i*PAGE_SIZE);
  253.             if (pte && PTE_VALID(pte)) {
  254.                 __address frame;
  255.  
  256.                 ASSERT(PTE_PRESENT(pte));
  257.                 frame = PTE_GET_FRAME(pte);
  258.                 page_mapping_remove(as, area->base + i*PAGE_SIZE);
  259.                 page_table_unlock(as, false);
  260.  
  261.                 frame_free(ADDR2PFN(frame));
  262.             } else {
  263.                 page_table_unlock(as, false);
  264.             }
  265.         }
  266.         /*
  267.          * Invalidate TLB's.
  268.          */
  269.         tlb_shootdown_start(TLB_INVL_PAGES, AS->asid, area->base + pages*PAGE_SIZE, area->pages - pages);
  270.         tlb_invalidate_pages(AS->asid, area->base + pages*PAGE_SIZE, area->pages - pages);
  271.         tlb_shootdown_finalize();
  272.     } else {
  273.         /*
  274.          * Growing the area.
  275.          * Check for overlaps with other address space areas.
  276.          */
  277.         if (!check_area_conflicts(as, address, pages * PAGE_SIZE, area)) {
  278.             spinlock_unlock(&area->lock);
  279.             spinlock_unlock(&as->lock);    
  280.             interrupts_restore(ipl);
  281.             return (__address) -1;
  282.         }
  283.     }
  284.  
  285.     area->pages = pages;
  286.    
  287.     spinlock_unlock(&area->lock);
  288.     spinlock_unlock(&as->lock);
  289.     interrupts_restore(ipl);
  290.  
  291.     return address;
  292. }
  293.  
  294. /** Send address space area to another task.
  295.  *
  296.  * Address space area is sent to the specified task.
  297.  * If the destination task is willing to accept the
  298.  * area, a new area is created according to the
  299.  * source area. Moreover, any existing mapping
  300.  * is copied as well, providing thus a mechanism
  301.  * for sharing group of pages. The source address
  302.  * space area and any associated mapping is preserved.
  303.  *
  304.  * @param dst_id Task ID of the accepting task.
  305.  * @param src_base Base address of the source address space area.
  306.  *
  307.  * @return 0 on success or ENOENT if there is no such task or
  308.  *     if there is no such address space area,
  309.  *     EPERM if there was a problem in accepting the area or
  310.  *     ENOMEM if there was a problem in allocating destination
  311.  *     address space area.
  312.  */
  313. int as_area_send(task_id_t dst_id, __address src_base)
  314. {
  315.     ipl_t ipl;
  316.     task_t *t;
  317.     count_t i;
  318.     as_t *dst_as;
  319.     __address dst_base;
  320.     int src_flags;
  321.     size_t src_size;
  322.     as_area_t *src_area, *dst_area;
  323.    
  324.     ipl = interrupts_disable();
  325.     spinlock_lock(&tasks_lock);
  326.    
  327.     t = task_find_by_id(dst_id);
  328.     if (!NULL) {
  329.         spinlock_unlock(&tasks_lock);
  330.         interrupts_restore(ipl);
  331.         return ENOENT;
  332.     }
  333.  
  334.     spinlock_lock(&t->lock);
  335.     spinlock_unlock(&tasks_lock);
  336.  
  337.     dst_as = t->as;
  338.     dst_base = (__address) t->accept_arg.base;
  339.    
  340.     if (dst_as == AS) {
  341.         /*
  342.          * The two tasks share the entire address space.
  343.          * Return error since there is no point in continuing.
  344.          */
  345.         spinlock_unlock(&t->lock);
  346.         interrupts_restore(ipl);
  347.         return EPERM;
  348.     }
  349.    
  350.     spinlock_lock(&AS->lock);
  351.     src_area = find_area_and_lock(AS, src_base);
  352.     if (!src_area) {
  353.         /*
  354.          * Could not find the source address space area.
  355.          */
  356.         spinlock_unlock(&t->lock);
  357.         spinlock_unlock(&AS->lock);
  358.         interrupts_restore(ipl);
  359.         return ENOENT;
  360.     }
  361.     src_size = src_area->pages * PAGE_SIZE;
  362.     src_flags = src_area->flags;
  363.     spinlock_unlock(&src_area->lock);
  364.     spinlock_unlock(&AS->lock);
  365.  
  366.     if ((t->accept_arg.task_id != TASK->taskid) || (t->accept_arg.size != src_size) ||
  367.         (t->accept_arg.flags != src_flags)) {
  368.         /*
  369.          * Discrepancy in either task ID, size or flags.
  370.          */
  371.         spinlock_unlock(&t->lock);
  372.         interrupts_restore(ipl);
  373.         return EPERM;
  374.     }
  375.    
  376.     /*
  377.      * Create copy of the source address space area.
  378.      * The destination area is created with AS_AREA_ATTR_PARTIAL
  379.      * attribute set which prevents race condition with
  380.      * preliminary as_page_fault() calls.
  381.      */
  382.     dst_area = as_area_create(dst_as, src_flags, src_size, dst_base, AS_AREA_ATTR_PARTIAL);
  383.     if (!dst_area) {
  384.         /*
  385.          * Destination address space area could not be created.
  386.          */
  387.         spinlock_unlock(&t->lock);
  388.         interrupts_restore(ipl);
  389.         return ENOMEM;
  390.     }
  391.    
  392.     memsetb((__address) &t->accept_arg, sizeof(as_area_acptsnd_arg_t), 0);
  393.     spinlock_unlock(&t->lock);
  394.    
  395.     /*
  396.      * Avoid deadlock by first locking the address space with lower address.
  397.      */
  398.     if (dst_as < AS) {
  399.         spinlock_lock(&dst_as->lock);
  400.         spinlock_lock(&AS->lock);
  401.     } else {
  402.         spinlock_lock(&AS->lock);
  403.         spinlock_lock(&dst_as->lock);
  404.     }
  405.    
  406.     for (i = 0; i < SIZE2FRAMES(src_size); i++) {
  407.         pte_t *pte;
  408.         __address frame;
  409.            
  410.         page_table_lock(AS, false);
  411.         pte = page_mapping_find(AS, src_base + i*PAGE_SIZE);
  412.         if (pte && PTE_VALID(pte)) {
  413.             ASSERT(PTE_PRESENT(pte));
  414.             frame = PTE_GET_FRAME(pte);
  415.             if (!(src_flags & AS_AREA_DEVICE))
  416.                 frame_reference_add(ADDR2PFN(frame));
  417.             page_table_unlock(AS, false);
  418.         } else {
  419.             page_table_unlock(AS, false);
  420.             continue;
  421.         }
  422.        
  423.         page_table_lock(dst_as, false);
  424.         page_mapping_insert(dst_as, dst_base + i*PAGE_SIZE, frame, area_flags_to_page_flags(src_flags));
  425.         page_table_unlock(dst_as, false);
  426.     }
  427.  
  428.     /*
  429.      * Now the destination address space area has been
  430.      * fully initialized. Clear the AS_AREA_ATTR_PARTIAL
  431.      * attribute.
  432.      */
  433.     spinlock_lock(&dst_area->lock);
  434.     dst_area->attributes &= ~AS_AREA_ATTR_PARTIAL;
  435.     spinlock_unlock(&dst_area->lock);
  436.    
  437.     spinlock_unlock(&AS->lock);
  438.     spinlock_unlock(&dst_as->lock);
  439.     interrupts_restore(ipl);
  440.    
  441.     return 0;
  442. }
  443.  
  444. /** Initialize mapping for one page of address space.
  445.  *
  446.  * This functions maps 'page' to 'frame' according
  447.  * to attributes of the address space area to
  448.  * wich 'page' belongs.
  449.  *
  450.  * @param as Target address space.
  451.  * @param page Virtual page within the area.
  452.  * @param frame Physical frame to which page will be mapped.
  453.  */
  454. void as_set_mapping(as_t *as, __address page, __address frame)
  455. {
  456.     as_area_t *area;
  457.     ipl_t ipl;
  458.    
  459.     ipl = interrupts_disable();
  460.     page_table_lock(as, true);
  461.    
  462.     area = find_area_and_lock(as, page);
  463.     if (!area) {
  464.         panic("page not part of any as_area\n");
  465.     }
  466.  
  467.     page_mapping_insert(as, page, frame, get_area_flags(area));
  468.    
  469.     spinlock_unlock(&area->lock);
  470.     page_table_unlock(as, true);
  471.     interrupts_restore(ipl);
  472. }
  473.  
  474. /** Handle page fault within the current address space.
  475.  *
  476.  * This is the high-level page fault handler.
  477.  * Interrupts are assumed disabled.
  478.  *
  479.  * @param page Faulting page.
  480.  *
  481.  * @return 0 on page fault, 1 on success.
  482.  */
  483. int as_page_fault(__address page)
  484. {
  485.     pte_t *pte;
  486.     as_area_t *area;
  487.     __address frame;
  488.    
  489.     ASSERT(AS);
  490.  
  491.     spinlock_lock(&AS->lock);
  492.     area = find_area_and_lock(AS, page);   
  493.     if (!area) {
  494.         /*
  495.          * No area contained mapping for 'page'.
  496.          * Signal page fault to low-level handler.
  497.          */
  498.         spinlock_unlock(&AS->lock);
  499.         return 0;
  500.     }
  501.  
  502.     if (area->attributes & AS_AREA_ATTR_PARTIAL) {
  503.         /*
  504.          * The address space area is not fully initialized.
  505.          * Avoid possible race by returning error.
  506.          */
  507.         spinlock_unlock(&area->lock);
  508.         spinlock_unlock(&AS->lock);
  509.         return 0;      
  510.     }
  511.  
  512.     ASSERT(!(area->flags & AS_AREA_DEVICE));
  513.  
  514.     page_table_lock(AS, false);
  515.    
  516.     /*
  517.      * To avoid race condition between two page faults
  518.      * on the same address, we need to make sure
  519.      * the mapping has not been already inserted.
  520.      */
  521.     if ((pte = page_mapping_find(AS, page))) {
  522.         if (PTE_PRESENT(pte)) {
  523.             page_table_unlock(AS, false);
  524.             spinlock_unlock(&area->lock);
  525.             spinlock_unlock(&AS->lock);
  526.             return 1;
  527.         }
  528.     }
  529.  
  530.     /*
  531.      * In general, there can be several reasons that
  532.      * can have caused this fault.
  533.      *
  534.      * - non-existent mapping: the area is a scratch
  535.      *   area (e.g. stack) and so far has not been
  536.      *   allocated a frame for the faulting page
  537.      *
  538.      * - non-present mapping: another possibility,
  539.      *   currently not implemented, would be frame
  540.      *   reuse; when this becomes a possibility,
  541.      *   do not forget to distinguish between
  542.      *   the different causes
  543.      */
  544.     frame = PFN2ADDR(frame_alloc(ONE_FRAME, 0));
  545.     memsetb(PA2KA(frame), FRAME_SIZE, 0);
  546.    
  547.     /*
  548.      * Map 'page' to 'frame'.
  549.      * Note that TLB shootdown is not attempted as only new information is being
  550.      * inserted into page tables.
  551.      */
  552.     page_mapping_insert(AS, page, frame, get_area_flags(area));
  553.     page_table_unlock(AS, false);
  554.    
  555.     spinlock_unlock(&area->lock);
  556.     spinlock_unlock(&AS->lock);
  557.     return 1;
  558. }
  559.  
  560. /** Switch address spaces.
  561.  *
  562.  * @param old Old address space or NULL.
  563.  * @param new New address space.
  564.  */
  565. void as_switch(as_t *old, as_t *new)
  566. {
  567.     ipl_t ipl;
  568.     bool needs_asid = false;
  569.    
  570.     ipl = interrupts_disable();
  571.     spinlock_lock(&as_lock);
  572.  
  573.     /*
  574.      * First, take care of the old address space.
  575.      */
  576.     if (old) {
  577.         spinlock_lock(&old->lock);
  578.         ASSERT(old->refcount);
  579.         if((--old->refcount == 0) && (old != AS_KERNEL)) {
  580.             /*
  581.              * The old address space is no longer active on
  582.              * any processor. It can be appended to the
  583.              * list of inactive address spaces with assigned
  584.              * ASID.
  585.              */
  586.              ASSERT(old->asid != ASID_INVALID);
  587.              list_append(&old->inactive_as_with_asid_link, &inactive_as_with_asid_head);
  588.         }
  589.         spinlock_unlock(&old->lock);
  590.     }
  591.  
  592.     /*
  593.      * Second, prepare the new address space.
  594.      */
  595.     spinlock_lock(&new->lock);
  596.     if ((new->refcount++ == 0) && (new != AS_KERNEL)) {
  597.         if (new->asid != ASID_INVALID)
  598.             list_remove(&new->inactive_as_with_asid_link);
  599.         else
  600.             needs_asid = true;  /* defer call to asid_get() until new->lock is released */
  601.     }
  602.     SET_PTL0_ADDRESS(new->page_table);
  603.     spinlock_unlock(&new->lock);
  604.  
  605.     if (needs_asid) {
  606.         /*
  607.          * Allocation of new ASID was deferred
  608.          * until now in order to avoid deadlock.
  609.          */
  610.         asid_t asid;
  611.        
  612.         asid = asid_get();
  613.         spinlock_lock(&new->lock);
  614.         new->asid = asid;
  615.         spinlock_unlock(&new->lock);
  616.     }
  617.     spinlock_unlock(&as_lock);
  618.     interrupts_restore(ipl);
  619.    
  620.     /*
  621.      * Perform architecture-specific steps.
  622.      * (e.g. write ASID to hardware register etc.)
  623.      */
  624.     as_install_arch(new);
  625.    
  626.     AS = new;
  627. }
  628.  
  629. /** Convert address space area flags to page flags.
  630.  *
  631.  * @param aflags Flags of some address space area.
  632.  *
  633.  * @return Flags to be passed to page_mapping_insert().
  634.  */
  635. int area_flags_to_page_flags(int aflags)
  636. {
  637.     int flags;
  638.  
  639.     flags = PAGE_USER | PAGE_PRESENT;
  640.    
  641.     if (aflags & AS_AREA_READ)
  642.         flags |= PAGE_READ;
  643.        
  644.     if (aflags & AS_AREA_WRITE)
  645.         flags |= PAGE_WRITE;
  646.    
  647.     if (aflags & AS_AREA_EXEC)
  648.         flags |= PAGE_EXEC;
  649.    
  650.     if (!(aflags & AS_AREA_DEVICE))
  651.         flags |= PAGE_CACHEABLE;
  652.        
  653.     return flags;
  654. }
  655.  
  656. /** Compute flags for virtual address translation subsytem.
  657.  *
  658.  * The address space area must be locked.
  659.  * Interrupts must be disabled.
  660.  *
  661.  * @param a Address space area.
  662.  *
  663.  * @return Flags to be used in page_mapping_insert().
  664.  */
  665. int get_area_flags(as_area_t *a)
  666. {
  667.     return area_flags_to_page_flags(a->flags);
  668. }
  669.  
  670. /** Create page table.
  671.  *
  672.  * Depending on architecture, create either address space
  673.  * private or global page table.
  674.  *
  675.  * @param flags Flags saying whether the page table is for kernel address space.
  676.  *
  677.  * @return First entry of the page table.
  678.  */
  679. pte_t *page_table_create(int flags)
  680. {
  681.         ASSERT(as_operations);
  682.         ASSERT(as_operations->page_table_create);
  683.  
  684.         return as_operations->page_table_create(flags);
  685. }
  686.  
  687. /** Lock page table.
  688.  *
  689.  * This function should be called before any page_mapping_insert(),
  690.  * page_mapping_remove() and page_mapping_find().
  691.  *
  692.  * Locking order is such that address space areas must be locked
  693.  * prior to this call. Address space can be locked prior to this
  694.  * call in which case the lock argument is false.
  695.  *
  696.  * @param as Address space.
  697.  * @param lock If false, do not attempt to lock as->lock.
  698.  */
  699. void page_table_lock(as_t *as, bool lock)
  700. {
  701.     ASSERT(as_operations);
  702.     ASSERT(as_operations->page_table_lock);
  703.  
  704.     as_operations->page_table_lock(as, lock);
  705. }
  706.  
  707. /** Unlock page table.
  708.  *
  709.  * @param as Address space.
  710.  * @param unlock If false, do not attempt to unlock as->lock.
  711.  */
  712. void page_table_unlock(as_t *as, bool unlock)
  713. {
  714.     ASSERT(as_operations);
  715.     ASSERT(as_operations->page_table_unlock);
  716.  
  717.     as_operations->page_table_unlock(as, unlock);
  718. }
  719.  
  720.  
  721. /** Find address space area and lock it.
  722.  *
  723.  * The address space must be locked and interrupts must be disabled.
  724.  *
  725.  * @param as Address space.
  726.  * @param va Virtual address.
  727.  *
  728.  * @return Locked address space area containing va on success or NULL on failure.
  729.  */
  730. as_area_t *find_area_and_lock(as_t *as, __address va)
  731. {
  732.     as_area_t *a;
  733.     btree_node_t *leaf, *lnode;
  734.     int i;
  735.    
  736.     a = (as_area_t *) btree_search(&as->as_area_btree, va, &leaf);
  737.     if (a) {
  738.         /* va is the base address of an address space area */
  739.         spinlock_lock(&a->lock);
  740.         return a;
  741.     }
  742.    
  743.     /*
  744.      * Search the leaf node and the righmost record of its left neighbour
  745.      * to find out whether this is a miss or va belongs to an address
  746.      * space area found there.
  747.      */
  748.    
  749.     /* First, search the leaf node itself. */
  750.     for (i = 0; i < leaf->keys; i++) {
  751.         a = (as_area_t *) leaf->value[i];
  752.         spinlock_lock(&a->lock);
  753.         if ((a->base <= va) && (va < a->base + a->pages * PAGE_SIZE)) {
  754.             return a;
  755.         }
  756.         spinlock_unlock(&a->lock);
  757.     }
  758.  
  759.     /*
  760.      * Second, locate the left neighbour and test its last record.
  761.      * Because of its position in the B+tree, it must have base < va.
  762.      */
  763.     if ((lnode = btree_leaf_node_left_neighbour(&as->as_area_btree, leaf))) {
  764.         a = (as_area_t *) lnode->value[lnode->keys - 1];
  765.         spinlock_lock(&a->lock);
  766.         if (va < a->base + a->pages * PAGE_SIZE) {
  767.             return a;
  768.         }
  769.         spinlock_unlock(&a->lock);
  770.     }
  771.  
  772.     return NULL;
  773. }
  774.  
  775. /** Check area conflicts with other areas.
  776.  *
  777.  * The address space must be locked and interrupts must be disabled.
  778.  *
  779.  * @param as Address space.
  780.  * @param va Starting virtual address of the area being tested.
  781.  * @param size Size of the area being tested.
  782.  * @param avoid_area Do not touch this area.
  783.  *
  784.  * @return True if there is no conflict, false otherwise.
  785.  */
  786. bool check_area_conflicts(as_t *as, __address va, size_t size, as_area_t *avoid_area)
  787. {
  788.     as_area_t *a;
  789.     btree_node_t *leaf, *node;
  790.     int i;
  791.    
  792.     /*
  793.      * We don't want any area to have conflicts with NULL page.
  794.      */
  795.     if (overlaps(va, size, NULL, PAGE_SIZE))
  796.         return false;
  797.    
  798.     /*
  799.      * The leaf node is found in O(log n), where n is proportional to
  800.      * the number of address space areas belonging to as.
  801.      * The check for conflicts is then attempted on the rightmost
  802.      * record in the left neighbour, the leftmost record in the right
  803.      * neighbour and all records in the leaf node itself.
  804.      */
  805.    
  806.     if ((a = (as_area_t *) btree_search(&as->as_area_btree, va, &leaf))) {
  807.         if (a != avoid_area)
  808.             return false;
  809.     }
  810.    
  811.     /* First, check the two border cases. */
  812.     if ((node = btree_leaf_node_left_neighbour(&as->as_area_btree, leaf))) {
  813.         a = (as_area_t *) node->value[node->keys - 1];
  814.         spinlock_lock(&a->lock);
  815.         if (overlaps(va, size, a->base, a->pages * PAGE_SIZE)) {
  816.             spinlock_unlock(&a->lock);
  817.             return false;
  818.         }
  819.         spinlock_unlock(&a->lock);
  820.     }
  821.     if ((node = btree_leaf_node_right_neighbour(&as->as_area_btree, leaf))) {
  822.         a = (as_area_t *) node->value[0];
  823.         spinlock_lock(&a->lock);
  824.         if (overlaps(va, size, a->base, a->pages * PAGE_SIZE)) {
  825.             spinlock_unlock(&a->lock);
  826.             return false;
  827.         }
  828.         spinlock_unlock(&a->lock);
  829.     }
  830.    
  831.     /* Second, check the leaf node. */
  832.     for (i = 0; i < leaf->keys; i++) {
  833.         a = (as_area_t *) leaf->value[i];
  834.    
  835.         if (a == avoid_area)
  836.             continue;
  837.    
  838.         spinlock_lock(&a->lock);
  839.         if (overlaps(va, size, a->base, a->pages * PAGE_SIZE)) {
  840.             spinlock_unlock(&a->lock);
  841.             return false;
  842.         }
  843.         spinlock_unlock(&a->lock);
  844.     }
  845.  
  846.     /*
  847.      * So far, the area does not conflict with other areas.
  848.      * Check if it doesn't conflict with kernel address space.
  849.      */  
  850.     if (!KERNEL_ADDRESS_SPACE_SHADOWED) {
  851.         return !overlaps(va, size,
  852.             KERNEL_ADDRESS_SPACE_START, KERNEL_ADDRESS_SPACE_END-KERNEL_ADDRESS_SPACE_START);
  853.     }
  854.  
  855.     return true;
  856. }
  857.  
  858. /*
  859.  * Address space related syscalls.
  860.  */
  861.  
  862. /** Wrapper for as_area_create(). */
  863. __native sys_as_area_create(__address address, size_t size, int flags)
  864. {
  865.     if (as_area_create(AS, flags, size, address, AS_AREA_ATTR_NONE))
  866.         return (__native) address;
  867.     else
  868.         return (__native) -1;
  869. }
  870.  
  871. /** Wrapper for as_area_resize. */
  872. __native sys_as_area_resize(__address address, size_t size, int flags)
  873. {
  874.     return as_area_resize(AS, address, size, 0);
  875. }
  876.  
  877. /** Prepare task for accepting address space area from another task.
  878.  *
  879.  * @param uspace_accept_arg Accept structure passed from userspace.
  880.  *
  881.  * @return EPERM if the task ID encapsulated in @uspace_accept_arg references
  882.  *     TASK. Otherwise zero is returned.
  883.  */
  884. __native sys_as_area_accept(as_area_acptsnd_arg_t *uspace_accept_arg)
  885. {
  886.     as_area_acptsnd_arg_t arg;
  887.    
  888.     copy_from_uspace(&arg, uspace_accept_arg, sizeof(as_area_acptsnd_arg_t));
  889.    
  890.     if (!arg.size)
  891.         return (__native) EPERM;
  892.    
  893.     if (arg.task_id == TASK->taskid) {
  894.         /*
  895.          * Accepting from itself is not allowed.
  896.          */
  897.         return (__native) EPERM;
  898.     }
  899.    
  900.     memcpy(&TASK->accept_arg, &arg, sizeof(as_area_acptsnd_arg_t));
  901.    
  902.         return 0;
  903. }
  904.  
  905. /** Wrapper for as_area_send. */
  906. __native sys_as_area_send(as_area_acptsnd_arg_t *uspace_send_arg)
  907. {
  908.     as_area_acptsnd_arg_t arg;
  909.    
  910.     copy_from_uspace(&arg, uspace_send_arg, sizeof(as_area_acptsnd_arg_t));
  911.  
  912.     if (!arg.size)
  913.         return (__native) EPERM;
  914.    
  915.     if (arg.task_id == TASK->taskid) {
  916.         /*
  917.          * Sending to itself is not allowed.
  918.          */
  919.         return (__native) EPERM;
  920.     }
  921.  
  922.     return (__native) as_area_send(arg.task_id, (__address) arg.base);
  923. }
  924.