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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 <proc/thread.h>
  61. #include <arch/asm.h>
  62. #include <panic.h>
  63. #include <debug.h>
  64. #include <print.h>
  65. #include <memstr.h>
  66. #include <macros.h>
  67. #include <arch.h>
  68. #include <errno.h>
  69. #include <config.h>
  70. #include <arch/types.h>
  71. #include <typedefs.h>
  72. #include <syscall/copy.h>
  73. #include <arch/interrupt.h>
  74.  
  75. as_operations_t *as_operations = NULL;
  76.  
  77. /** Address space lock. It protects inactive_as_with_asid_head. */
  78. SPINLOCK_INITIALIZE(as_lock);
  79.  
  80. /**
  81.  * This list contains address spaces that are not active on any
  82.  * processor and that have valid ASID.
  83.  */
  84. LIST_INITIALIZE(inactive_as_with_asid_head);
  85.  
  86. /** Kernel address space. */
  87. as_t *AS_KERNEL = NULL;
  88.  
  89. static int area_flags_to_page_flags(int aflags);
  90. static int get_area_flags(as_area_t *a);
  91. static as_area_t *find_area_and_lock(as_t *as, __address va);
  92. static bool check_area_conflicts(as_t *as, __address va, size_t size, as_area_t *avoid_area);
  93.  
  94. /** Initialize address space subsystem. */
  95. void as_init(void)
  96. {
  97.     as_arch_init();
  98.     AS_KERNEL = as_create(FLAG_AS_KERNEL);
  99.         if (!AS_KERNEL)
  100.                 panic("can't create kernel address space\n");
  101. }
  102.  
  103. /** Create address space.
  104.  *
  105.  * @param flags Flags that influence way in wich the address space is created.
  106.  */
  107. as_t *as_create(int flags)
  108. {
  109.     as_t *as;
  110.  
  111.     as = (as_t *) malloc(sizeof(as_t), 0);
  112.     link_initialize(&as->inactive_as_with_asid_link);
  113.     spinlock_initialize(&as->lock, "as_lock");
  114.     btree_create(&as->as_area_btree);
  115.    
  116.     if (flags & FLAG_AS_KERNEL)
  117.         as->asid = ASID_KERNEL;
  118.     else
  119.         as->asid = ASID_INVALID;
  120.    
  121.     as->refcount = 0;
  122.     as->page_table = page_table_create(flags);
  123.  
  124.     return as;
  125. }
  126.  
  127. /** Free Adress space */
  128. void as_free(as_t *as)
  129. {
  130.     ASSERT(as->refcount == 0);
  131.  
  132.     /* TODO: free as_areas and other resources held by as */
  133.     /* TODO: free page table */
  134.     free(as);
  135. }
  136.  
  137. /** Create address space area of common attributes.
  138.  *
  139.  * The created address space area is added to the target address space.
  140.  *
  141.  * @param as Target address space.
  142.  * @param flags Flags of the area memory.
  143.  * @param size Size of area.
  144.  * @param base Base address of area.
  145.  * @param attrs Attributes of the area.
  146.  *
  147.  * @return Address space area on success or NULL on failure.
  148.  */
  149. as_area_t *as_area_create(as_t *as, int flags, size_t size, __address base, int attrs)
  150. {
  151.     ipl_t ipl;
  152.     as_area_t *a;
  153.    
  154.     if (base % PAGE_SIZE)
  155.         return NULL;
  156.  
  157.     if (!size)
  158.         return NULL;
  159.  
  160.     /* Writeable executable areas are not supported. */
  161.     if ((flags & AS_AREA_EXEC) && (flags & AS_AREA_WRITE))
  162.         return NULL;
  163.    
  164.     ipl = interrupts_disable();
  165.     spinlock_lock(&as->lock);
  166.    
  167.     if (!check_area_conflicts(as, base, size, NULL)) {
  168.         spinlock_unlock(&as->lock);
  169.         interrupts_restore(ipl);
  170.         return NULL;
  171.     }
  172.    
  173.     a = (as_area_t *) malloc(sizeof(as_area_t), 0);
  174.  
  175.     spinlock_initialize(&a->lock, "as_area_lock");
  176.    
  177.     a->flags = flags;
  178.     a->attributes = attrs;
  179.     a->pages = SIZE2FRAMES(size);
  180.     a->base = base;
  181.    
  182.     btree_insert(&as->as_area_btree, base, (void *) a, NULL);
  183.  
  184.     spinlock_unlock(&as->lock);
  185.     interrupts_restore(ipl);
  186.  
  187.     return a;
  188. }
  189.  
  190. /** Find address space area and change it.
  191.  *
  192.  * @param as Address space.
  193.  * @param address Virtual address belonging to the area to be changed. Must be page-aligned.
  194.  * @param size New size of the virtual memory block starting at address.
  195.  * @param flags Flags influencing the remap operation. Currently unused.
  196.  *
  197.  * @return address on success, (__address) -1 otherwise.
  198.  */
  199. __address as_area_resize(as_t *as, __address address, size_t size, int flags)
  200. {
  201.     as_area_t *area = NULL;
  202.     ipl_t ipl;
  203.     size_t pages;
  204.    
  205.     ipl = interrupts_disable();
  206.     spinlock_lock(&as->lock);
  207.    
  208.     /*
  209.      * Locate the area.
  210.      */
  211.     area = find_area_and_lock(as, address);
  212.     if (!area) {
  213.         spinlock_unlock(&as->lock);
  214.         interrupts_restore(ipl);
  215.         return (__address) -1;
  216.     }
  217.  
  218.     if (area->flags & AS_AREA_DEVICE) {
  219.         /*
  220.          * Remapping of address space areas associated
  221.          * with memory mapped devices is not supported.
  222.          */
  223.         spinlock_unlock(&area->lock);
  224.         spinlock_unlock(&as->lock);
  225.         interrupts_restore(ipl);
  226.         return (__address) -1;
  227.     }
  228.  
  229.     pages = SIZE2FRAMES((address - area->base) + size);
  230.     if (!pages) {
  231.         /*
  232.          * Zero size address space areas are not allowed.
  233.          */
  234.         spinlock_unlock(&area->lock);
  235.         spinlock_unlock(&as->lock);
  236.         interrupts_restore(ipl);
  237.         return (__address) -1;
  238.     }
  239.    
  240.     if (pages < area->pages) {
  241.         int i;
  242.  
  243.         /*
  244.          * Shrinking the area.
  245.          * No need to check for overlaps.
  246.          */
  247.         for (i = pages; i < area->pages; i++) {
  248.             pte_t *pte;
  249.            
  250.             /*
  251.              * Releasing physical memory.
  252.              * This depends on the fact that the memory was allocated using frame_alloc().
  253.              */
  254.             page_table_lock(as, false);
  255.             pte = page_mapping_find(as, area->base + i*PAGE_SIZE);
  256.             if (pte && PTE_VALID(pte)) {
  257.                 __address frame;
  258.  
  259.                 ASSERT(PTE_PRESENT(pte));
  260.                 frame = PTE_GET_FRAME(pte);
  261.                 page_mapping_remove(as, area->base + i*PAGE_SIZE);
  262.                 page_table_unlock(as, false);
  263.  
  264.                 frame_free(ADDR2PFN(frame));
  265.             } else {
  266.                 page_table_unlock(as, false);
  267.             }
  268.         }
  269.         /*
  270.          * Invalidate TLB's.
  271.          */
  272.         tlb_shootdown_start(TLB_INVL_PAGES, AS->asid, area->base + pages*PAGE_SIZE, area->pages - pages);
  273.         tlb_invalidate_pages(AS->asid, area->base + pages*PAGE_SIZE, area->pages - pages);
  274.         tlb_shootdown_finalize();
  275.     } else {
  276.         /*
  277.          * Growing the area.
  278.          * Check for overlaps with other address space areas.
  279.          */
  280.         if (!check_area_conflicts(as, address, pages * PAGE_SIZE, area)) {
  281.             spinlock_unlock(&area->lock);
  282.             spinlock_unlock(&as->lock);    
  283.             interrupts_restore(ipl);
  284.             return (__address) -1;
  285.         }
  286.     }
  287.  
  288.     area->pages = pages;
  289.    
  290.     spinlock_unlock(&area->lock);
  291.     spinlock_unlock(&as->lock);
  292.     interrupts_restore(ipl);
  293.  
  294.     return address;
  295. }
  296.  
  297. /** Send address space area to another task.
  298.  *
  299.  * Address space area is sent to the specified task.
  300.  * If the destination task is willing to accept the
  301.  * area, a new area is created according to the
  302.  * source area. Moreover, any existing mapping
  303.  * is copied as well, providing thus a mechanism
  304.  * for sharing group of pages. The source address
  305.  * space area and any associated mapping is preserved.
  306.  *
  307.  * @param dst_id Task ID of the accepting task.
  308.  * @param src_base Base address of the source address space area.
  309.  *
  310.  * @return 0 on success or ENOENT if there is no such task or
  311.  *     if there is no such address space area,
  312.  *     EPERM if there was a problem in accepting the area or
  313.  *     ENOMEM if there was a problem in allocating destination
  314.  *     address space area.
  315.  */
  316. int as_area_send(task_id_t dst_id, __address src_base)
  317. {
  318.     ipl_t ipl;
  319.     task_t *t;
  320.     count_t i;
  321.     as_t *dst_as;
  322.     __address dst_base;
  323.     int src_flags;
  324.     size_t src_size;
  325.     as_area_t *src_area, *dst_area;
  326.    
  327.     ipl = interrupts_disable();
  328.     spinlock_lock(&tasks_lock);
  329.    
  330.     t = task_find_by_id(dst_id);
  331.     if (!NULL) {
  332.         spinlock_unlock(&tasks_lock);
  333.         interrupts_restore(ipl);
  334.         return ENOENT;
  335.     }
  336.  
  337.     spinlock_lock(&t->lock);
  338.     spinlock_unlock(&tasks_lock);
  339.  
  340.     dst_as = t->as;
  341.     dst_base = (__address) t->accept_arg.base;
  342.    
  343.     if (dst_as == AS) {
  344.         /*
  345.          * The two tasks share the entire address space.
  346.          * Return error since there is no point in continuing.
  347.          */
  348.         spinlock_unlock(&t->lock);
  349.         interrupts_restore(ipl);
  350.         return EPERM;
  351.     }
  352.    
  353.     spinlock_lock(&AS->lock);
  354.     src_area = find_area_and_lock(AS, src_base);
  355.     if (!src_area) {
  356.         /*
  357.          * Could not find the source address space area.
  358.          */
  359.         spinlock_unlock(&t->lock);
  360.         spinlock_unlock(&AS->lock);
  361.         interrupts_restore(ipl);
  362.         return ENOENT;
  363.     }
  364.     src_size = src_area->pages * PAGE_SIZE;
  365.     src_flags = src_area->flags;
  366.     spinlock_unlock(&src_area->lock);
  367.     spinlock_unlock(&AS->lock);
  368.  
  369.     if ((t->accept_arg.task_id != TASK->taskid) || (t->accept_arg.size != src_size) ||
  370.         (t->accept_arg.flags != src_flags)) {
  371.         /*
  372.          * Discrepancy in either task ID, size or flags.
  373.          */
  374.         spinlock_unlock(&t->lock);
  375.         interrupts_restore(ipl);
  376.         return EPERM;
  377.     }
  378.    
  379.     /*
  380.      * Create copy of the source address space area.
  381.      * The destination area is created with AS_AREA_ATTR_PARTIAL
  382.      * attribute set which prevents race condition with
  383.      * preliminary as_page_fault() calls.
  384.      */
  385.     dst_area = as_area_create(dst_as, src_flags, src_size, dst_base, AS_AREA_ATTR_PARTIAL);
  386.     if (!dst_area) {
  387.         /*
  388.          * Destination address space area could not be created.
  389.          */
  390.         spinlock_unlock(&t->lock);
  391.         interrupts_restore(ipl);
  392.         return ENOMEM;
  393.     }
  394.    
  395.     memsetb((__address) &t->accept_arg, sizeof(as_area_acptsnd_arg_t), 0);
  396.     spinlock_unlock(&t->lock);
  397.    
  398.     /*
  399.      * Avoid deadlock by first locking the address space with lower address.
  400.      */
  401.     if (dst_as < AS) {
  402.         spinlock_lock(&dst_as->lock);
  403.         spinlock_lock(&AS->lock);
  404.     } else {
  405.         spinlock_lock(&AS->lock);
  406.         spinlock_lock(&dst_as->lock);
  407.     }
  408.    
  409.     for (i = 0; i < SIZE2FRAMES(src_size); i++) {
  410.         pte_t *pte;
  411.         __address frame;
  412.            
  413.         page_table_lock(AS, false);
  414.         pte = page_mapping_find(AS, src_base + i*PAGE_SIZE);
  415.         if (pte && PTE_VALID(pte)) {
  416.             ASSERT(PTE_PRESENT(pte));
  417.             frame = PTE_GET_FRAME(pte);
  418.             if (!(src_flags & AS_AREA_DEVICE))
  419.                 frame_reference_add(ADDR2PFN(frame));
  420.             page_table_unlock(AS, false);
  421.         } else {
  422.             page_table_unlock(AS, false);
  423.             continue;
  424.         }
  425.        
  426.         page_table_lock(dst_as, false);
  427.         page_mapping_insert(dst_as, dst_base + i*PAGE_SIZE, frame, area_flags_to_page_flags(src_flags));
  428.         page_table_unlock(dst_as, false);
  429.     }
  430.  
  431.     /*
  432.      * Now the destination address space area has been
  433.      * fully initialized. Clear the AS_AREA_ATTR_PARTIAL
  434.      * attribute.
  435.      */
  436.     spinlock_lock(&dst_area->lock);
  437.     dst_area->attributes &= ~AS_AREA_ATTR_PARTIAL;
  438.     spinlock_unlock(&dst_area->lock);
  439.    
  440.     spinlock_unlock(&AS->lock);
  441.     spinlock_unlock(&dst_as->lock);
  442.     interrupts_restore(ipl);
  443.    
  444.     return 0;
  445. }
  446.  
  447. /** Initialize mapping for one page of address space.
  448.  *
  449.  * This functions maps 'page' to 'frame' according
  450.  * to attributes of the address space area to
  451.  * wich 'page' belongs.
  452.  *
  453.  * @param as Target address space.
  454.  * @param page Virtual page within the area.
  455.  * @param frame Physical frame to which page will be mapped.
  456.  */
  457. void as_set_mapping(as_t *as, __address page, __address frame)
  458. {
  459.     as_area_t *area;
  460.     ipl_t ipl;
  461.    
  462.     ipl = interrupts_disable();
  463.     page_table_lock(as, true);
  464.    
  465.     area = find_area_and_lock(as, page);
  466.     if (!area) {
  467.         panic("page not part of any as_area\n");
  468.     }
  469.  
  470.     page_mapping_insert(as, page, frame, get_area_flags(area));
  471.    
  472.     spinlock_unlock(&area->lock);
  473.     page_table_unlock(as, true);
  474.     interrupts_restore(ipl);
  475. }
  476.  
  477. /** Handle page fault within the current address space.
  478.  *
  479.  * This is the high-level page fault handler.
  480.  * Interrupts are assumed disabled.
  481.  *
  482.  * @param page Faulting page.
  483.  * @param istate Pointer to interrupted state.
  484.  *
  485.  * @return 0 on page fault, 1 on success or 2 if the fault was caused by copy_to_uspace() or copy_from_uspace().
  486.  */
  487. int as_page_fault(__address page, istate_t *istate)
  488. {
  489.     pte_t *pte;
  490.     as_area_t *area;
  491.     __address frame;
  492.    
  493.     ASSERT(AS);
  494.  
  495.     spinlock_lock(&AS->lock);
  496.     area = find_area_and_lock(AS, page);   
  497.     if (!area) {
  498.         /*
  499.          * No area contained mapping for 'page'.
  500.          * Signal page fault to low-level handler.
  501.          */
  502.         spinlock_unlock(&AS->lock);
  503.         goto page_fault;
  504.     }
  505.  
  506.     if (area->attributes & AS_AREA_ATTR_PARTIAL) {
  507.         /*
  508.          * The address space area is not fully initialized.
  509.          * Avoid possible race by returning error.
  510.          */
  511.         spinlock_unlock(&area->lock);
  512.         spinlock_unlock(&AS->lock);
  513.         goto page_fault;       
  514.     }
  515.  
  516.     ASSERT(!(area->flags & AS_AREA_DEVICE));
  517.  
  518.     page_table_lock(AS, false);
  519.    
  520.     /*
  521.      * To avoid race condition between two page faults
  522.      * on the same address, we need to make sure
  523.      * the mapping has not been already inserted.
  524.      */
  525.     if ((pte = page_mapping_find(AS, page))) {
  526.         if (PTE_PRESENT(pte)) {
  527.             page_table_unlock(AS, false);
  528.             spinlock_unlock(&area->lock);
  529.             spinlock_unlock(&AS->lock);
  530.             return 1;
  531.         }
  532.     }
  533.  
  534.     /*
  535.      * In general, there can be several reasons that
  536.      * can have caused this fault.
  537.      *
  538.      * - non-existent mapping: the area is a scratch
  539.      *   area (e.g. stack) and so far has not been
  540.      *   allocated a frame for the faulting page
  541.      *
  542.      * - non-present mapping: another possibility,
  543.      *   currently not implemented, would be frame
  544.      *   reuse; when this becomes a possibility,
  545.      *   do not forget to distinguish between
  546.      *   the different causes
  547.      */
  548.     frame = PFN2ADDR(frame_alloc(ONE_FRAME, 0));
  549.     memsetb(PA2KA(frame), FRAME_SIZE, 0);
  550.    
  551.     /*
  552.      * Map 'page' to 'frame'.
  553.      * Note that TLB shootdown is not attempted as only new information is being
  554.      * inserted into page tables.
  555.      */
  556.     page_mapping_insert(AS, page, frame, get_area_flags(area));
  557.     page_table_unlock(AS, false);
  558.    
  559.     spinlock_unlock(&area->lock);
  560.     spinlock_unlock(&AS->lock);
  561.     return AS_PF_OK;
  562.  
  563. page_fault:
  564.     if (!THREAD)
  565.         return AS_PF_FAULT;
  566.    
  567.     if (THREAD->in_copy_from_uspace) {
  568.         THREAD->in_copy_from_uspace = false;
  569.         istate_set_retaddr(istate, (__address) &memcpy_from_uspace_failover_address);
  570.     } else if (THREAD->in_copy_to_uspace) {
  571.         THREAD->in_copy_to_uspace = false;
  572.         istate_set_retaddr(istate, (__address) &memcpy_to_uspace_failover_address);
  573.     } else {
  574.         return AS_PF_FAULT;
  575.     }
  576.  
  577.     return AS_PF_DEFER;
  578. }
  579.  
  580. /** Switch address spaces.
  581.  *
  582.  * @param old Old address space or NULL.
  583.  * @param new New address space.
  584.  */
  585. void as_switch(as_t *old, as_t *new)
  586. {
  587.     ipl_t ipl;
  588.     bool needs_asid = false;
  589.    
  590.     ipl = interrupts_disable();
  591.     spinlock_lock(&as_lock);
  592.  
  593.     /*
  594.      * First, take care of the old address space.
  595.      */
  596.     if (old) {
  597.         spinlock_lock(&old->lock);
  598.         ASSERT(old->refcount);
  599.         if((--old->refcount == 0) && (old != AS_KERNEL)) {
  600.             /*
  601.              * The old address space is no longer active on
  602.              * any processor. It can be appended to the
  603.              * list of inactive address spaces with assigned
  604.              * ASID.
  605.              */
  606.              ASSERT(old->asid != ASID_INVALID);
  607.              list_append(&old->inactive_as_with_asid_link, &inactive_as_with_asid_head);
  608.         }
  609.         spinlock_unlock(&old->lock);
  610.     }
  611.  
  612.     /*
  613.      * Second, prepare the new address space.
  614.      */
  615.     spinlock_lock(&new->lock);
  616.     if ((new->refcount++ == 0) && (new != AS_KERNEL)) {
  617.         if (new->asid != ASID_INVALID)
  618.             list_remove(&new->inactive_as_with_asid_link);
  619.         else
  620.             needs_asid = true;  /* defer call to asid_get() until new->lock is released */
  621.     }
  622.     SET_PTL0_ADDRESS(new->page_table);
  623.     spinlock_unlock(&new->lock);
  624.  
  625.     if (needs_asid) {
  626.         /*
  627.          * Allocation of new ASID was deferred
  628.          * until now in order to avoid deadlock.
  629.          */
  630.         asid_t asid;
  631.        
  632.         asid = asid_get();
  633.         spinlock_lock(&new->lock);
  634.         new->asid = asid;
  635.         spinlock_unlock(&new->lock);
  636.     }
  637.     spinlock_unlock(&as_lock);
  638.     interrupts_restore(ipl);
  639.    
  640.     /*
  641.      * Perform architecture-specific steps.
  642.      * (e.g. write ASID to hardware register etc.)
  643.      */
  644.     as_install_arch(new);
  645.    
  646.     AS = new;
  647. }
  648.  
  649. /** Convert address space area flags to page flags.
  650.  *
  651.  * @param aflags Flags of some address space area.
  652.  *
  653.  * @return Flags to be passed to page_mapping_insert().
  654.  */
  655. int area_flags_to_page_flags(int aflags)
  656. {
  657.     int flags;
  658.  
  659.     flags = PAGE_USER | PAGE_PRESENT;
  660.    
  661.     if (aflags & AS_AREA_READ)
  662.         flags |= PAGE_READ;
  663.        
  664.     if (aflags & AS_AREA_WRITE)
  665.         flags |= PAGE_WRITE;
  666.    
  667.     if (aflags & AS_AREA_EXEC)
  668.         flags |= PAGE_EXEC;
  669.    
  670.     if (!(aflags & AS_AREA_DEVICE))
  671.         flags |= PAGE_CACHEABLE;
  672.        
  673.     return flags;
  674. }
  675.  
  676. /** Compute flags for virtual address translation subsytem.
  677.  *
  678.  * The address space area must be locked.
  679.  * Interrupts must be disabled.
  680.  *
  681.  * @param a Address space area.
  682.  *
  683.  * @return Flags to be used in page_mapping_insert().
  684.  */
  685. int get_area_flags(as_area_t *a)
  686. {
  687.     return area_flags_to_page_flags(a->flags);
  688. }
  689.  
  690. /** Create page table.
  691.  *
  692.  * Depending on architecture, create either address space
  693.  * private or global page table.
  694.  *
  695.  * @param flags Flags saying whether the page table is for kernel address space.
  696.  *
  697.  * @return First entry of the page table.
  698.  */
  699. pte_t *page_table_create(int flags)
  700. {
  701.         ASSERT(as_operations);
  702.         ASSERT(as_operations->page_table_create);
  703.  
  704.         return as_operations->page_table_create(flags);
  705. }
  706.  
  707. /** Lock page table.
  708.  *
  709.  * This function should be called before any page_mapping_insert(),
  710.  * page_mapping_remove() and page_mapping_find().
  711.  *
  712.  * Locking order is such that address space areas must be locked
  713.  * prior to this call. Address space can be locked prior to this
  714.  * call in which case the lock argument is false.
  715.  *
  716.  * @param as Address space.
  717.  * @param lock If false, do not attempt to lock as->lock.
  718.  */
  719. void page_table_lock(as_t *as, bool lock)
  720. {
  721.     ASSERT(as_operations);
  722.     ASSERT(as_operations->page_table_lock);
  723.  
  724.     as_operations->page_table_lock(as, lock);
  725. }
  726.  
  727. /** Unlock page table.
  728.  *
  729.  * @param as Address space.
  730.  * @param unlock If false, do not attempt to unlock as->lock.
  731.  */
  732. void page_table_unlock(as_t *as, bool unlock)
  733. {
  734.     ASSERT(as_operations);
  735.     ASSERT(as_operations->page_table_unlock);
  736.  
  737.     as_operations->page_table_unlock(as, unlock);
  738. }
  739.  
  740.  
  741. /** Find address space area and lock it.
  742.  *
  743.  * The address space must be locked and interrupts must be disabled.
  744.  *
  745.  * @param as Address space.
  746.  * @param va Virtual address.
  747.  *
  748.  * @return Locked address space area containing va on success or NULL on failure.
  749.  */
  750. as_area_t *find_area_and_lock(as_t *as, __address va)
  751. {
  752.     as_area_t *a;
  753.     btree_node_t *leaf, *lnode;
  754.     int i;
  755.    
  756.     a = (as_area_t *) btree_search(&as->as_area_btree, va, &leaf);
  757.     if (a) {
  758.         /* va is the base address of an address space area */
  759.         spinlock_lock(&a->lock);
  760.         return a;
  761.     }
  762.    
  763.     /*
  764.      * Search the leaf node and the righmost record of its left neighbour
  765.      * to find out whether this is a miss or va belongs to an address
  766.      * space area found there.
  767.      */
  768.    
  769.     /* First, search the leaf node itself. */
  770.     for (i = 0; i < leaf->keys; i++) {
  771.         a = (as_area_t *) leaf->value[i];
  772.         spinlock_lock(&a->lock);
  773.         if ((a->base <= va) && (va < a->base + a->pages * PAGE_SIZE)) {
  774.             return a;
  775.         }
  776.         spinlock_unlock(&a->lock);
  777.     }
  778.  
  779.     /*
  780.      * Second, locate the left neighbour and test its last record.
  781.      * Because of its position in the B+tree, it must have base < va.
  782.      */
  783.     if ((lnode = btree_leaf_node_left_neighbour(&as->as_area_btree, leaf))) {
  784.         a = (as_area_t *) lnode->value[lnode->keys - 1];
  785.         spinlock_lock(&a->lock);
  786.         if (va < a->base + a->pages * PAGE_SIZE) {
  787.             return a;
  788.         }
  789.         spinlock_unlock(&a->lock);
  790.     }
  791.  
  792.     return NULL;
  793. }
  794.  
  795. /** Check area conflicts with other areas.
  796.  *
  797.  * The address space must be locked and interrupts must be disabled.
  798.  *
  799.  * @param as Address space.
  800.  * @param va Starting virtual address of the area being tested.
  801.  * @param size Size of the area being tested.
  802.  * @param avoid_area Do not touch this area.
  803.  *
  804.  * @return True if there is no conflict, false otherwise.
  805.  */
  806. bool check_area_conflicts(as_t *as, __address va, size_t size, as_area_t *avoid_area)
  807. {
  808.     as_area_t *a;
  809.     btree_node_t *leaf, *node;
  810.     int i;
  811.    
  812.     /*
  813.      * We don't want any area to have conflicts with NULL page.
  814.      */
  815.     if (overlaps(va, size, NULL, PAGE_SIZE))
  816.         return false;
  817.    
  818.     /*
  819.      * The leaf node is found in O(log n), where n is proportional to
  820.      * the number of address space areas belonging to as.
  821.      * The check for conflicts is then attempted on the rightmost
  822.      * record in the left neighbour, the leftmost record in the right
  823.      * neighbour and all records in the leaf node itself.
  824.      */
  825.    
  826.     if ((a = (as_area_t *) btree_search(&as->as_area_btree, va, &leaf))) {
  827.         if (a != avoid_area)
  828.             return false;
  829.     }
  830.    
  831.     /* First, check the two border cases. */
  832.     if ((node = btree_leaf_node_left_neighbour(&as->as_area_btree, leaf))) {
  833.         a = (as_area_t *) node->value[node->keys - 1];
  834.         spinlock_lock(&a->lock);
  835.         if (overlaps(va, size, a->base, a->pages * PAGE_SIZE)) {
  836.             spinlock_unlock(&a->lock);
  837.             return false;
  838.         }
  839.         spinlock_unlock(&a->lock);
  840.     }
  841.     if ((node = btree_leaf_node_right_neighbour(&as->as_area_btree, leaf))) {
  842.         a = (as_area_t *) node->value[0];
  843.         spinlock_lock(&a->lock);
  844.         if (overlaps(va, size, a->base, a->pages * PAGE_SIZE)) {
  845.             spinlock_unlock(&a->lock);
  846.             return false;
  847.         }
  848.         spinlock_unlock(&a->lock);
  849.     }
  850.    
  851.     /* Second, check the leaf node. */
  852.     for (i = 0; i < leaf->keys; i++) {
  853.         a = (as_area_t *) leaf->value[i];
  854.    
  855.         if (a == avoid_area)
  856.             continue;
  857.    
  858.         spinlock_lock(&a->lock);
  859.         if (overlaps(va, size, a->base, a->pages * PAGE_SIZE)) {
  860.             spinlock_unlock(&a->lock);
  861.             return false;
  862.         }
  863.         spinlock_unlock(&a->lock);
  864.     }
  865.  
  866.     /*
  867.      * So far, the area does not conflict with other areas.
  868.      * Check if it doesn't conflict with kernel address space.
  869.      */  
  870.     if (!KERNEL_ADDRESS_SPACE_SHADOWED) {
  871.         return !overlaps(va, size,
  872.             KERNEL_ADDRESS_SPACE_START, KERNEL_ADDRESS_SPACE_END-KERNEL_ADDRESS_SPACE_START);
  873.     }
  874.  
  875.     return true;
  876. }
  877.  
  878. /*
  879.  * Address space related syscalls.
  880.  */
  881.  
  882. /** Wrapper for as_area_create(). */
  883. __native sys_as_area_create(__address address, size_t size, int flags)
  884. {
  885.     if (as_area_create(AS, flags, size, address, AS_AREA_ATTR_NONE))
  886.         return (__native) address;
  887.     else
  888.         return (__native) -1;
  889. }
  890.  
  891. /** Wrapper for as_area_resize. */
  892. __native sys_as_area_resize(__address address, size_t size, int flags)
  893. {
  894.     return as_area_resize(AS, address, size, 0);
  895. }
  896.  
  897. /** Prepare task for accepting address space area from another task.
  898.  *
  899.  * @param uspace_accept_arg Accept structure passed from userspace.
  900.  *
  901.  * @return EPERM if the task ID encapsulated in @uspace_accept_arg references
  902.  *     TASK. Otherwise zero is returned.
  903.  */
  904. __native sys_as_area_accept(as_area_acptsnd_arg_t *uspace_accept_arg)
  905. {
  906.     as_area_acptsnd_arg_t arg;
  907.     int rc;
  908.    
  909.     rc = copy_from_uspace(&arg, uspace_accept_arg, sizeof(as_area_acptsnd_arg_t));
  910.     if (rc != 0)
  911.         return rc;
  912.    
  913.     if (!arg.size)
  914.         return (__native) EPERM;
  915.    
  916.     if (arg.task_id == TASK->taskid) {
  917.         /*
  918.          * Accepting from itself is not allowed.
  919.          */
  920.         return (__native) EPERM;
  921.     }
  922.    
  923.     memcpy(&TASK->accept_arg, &arg, sizeof(as_area_acptsnd_arg_t));
  924.    
  925.         return 0;
  926. }
  927.  
  928. /** Wrapper for as_area_send. */
  929. __native sys_as_area_send(as_area_acptsnd_arg_t *uspace_send_arg)
  930. {
  931.     as_area_acptsnd_arg_t arg;
  932.     int rc;
  933.    
  934.     rc = copy_from_uspace(&arg, uspace_send_arg, sizeof(as_area_acptsnd_arg_t));
  935.     if (rc != 0)
  936.         return rc;
  937.  
  938.     if (!arg.size)
  939.         return (__native) EPERM;
  940.    
  941.     if (arg.task_id == TASK->taskid) {
  942.         /*
  943.          * Sending to itself is not allowed.
  944.          */
  945.         return (__native) EPERM;
  946.     }
  947.  
  948.     return (__native) as_area_send(arg.task_id, (__address) arg.base);
  949. }
  950.