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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 Zero on success or a value from @ref errno.h otherwise.
  198.  */
  199. int as_area_resize(as_t *as, __address address, size_t size, int flags)
  200. {
  201.     as_area_t *area;
  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 ENOENT;
  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 ENOTSUP;
  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 EPERM;
  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 EADDRNOTAVAIL;
  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 0;
  295. }
  296.  
  297. /** Destroy address space area.
  298.  *
  299.  * @param as Address space.
  300.  * @param address Address withing the area to be deleted.
  301.  *
  302.  * @return Zero on success or a value from @ref errno.h on failure.
  303.  */
  304. int as_area_destroy(as_t *as, __address address)
  305. {
  306.     as_area_t *area;
  307.     __address base;
  308.     ipl_t ipl;
  309.     int i;
  310.  
  311.     ipl = interrupts_disable();
  312.     spinlock_lock(&as->lock);
  313.  
  314.     area = find_area_and_lock(as, address);
  315.     if (!area) {
  316.         spinlock_unlock(&as->lock);
  317.         interrupts_restore(ipl);
  318.         return ENOENT;
  319.     }
  320.  
  321.     base = area->base; 
  322.     for (i = 0; i < area->pages; i++) {
  323.         pte_t *pte;
  324.  
  325.         /*
  326.          * Releasing physical memory.
  327.          * Areas mapping memory-mapped devices are treated differently than
  328.          * areas backing frame_alloc()'ed memory.
  329.          */
  330.         page_table_lock(as, false);
  331.         pte = page_mapping_find(as, area->base + i*PAGE_SIZE);
  332.         if (pte && PTE_VALID(pte)) {
  333.             ASSERT(PTE_PRESENT(pte));
  334.             page_mapping_remove(as, area->base + i*PAGE_SIZE);
  335.             if (area->flags & AS_AREA_DEVICE) {
  336.                 __address frame;
  337.                 frame = PTE_GET_FRAME(pte);
  338.                 frame_free(ADDR2PFN(frame));
  339.             }
  340.             page_table_unlock(as, false);
  341.         } else {
  342.             page_table_unlock(as, false);
  343.         }
  344.     }
  345.     /*
  346.      * Invalidate TLB's.
  347.      */
  348.     tlb_shootdown_start(TLB_INVL_PAGES, AS->asid, area->base, area->pages);
  349.     tlb_invalidate_pages(AS->asid, area->base, area->pages);
  350.     tlb_shootdown_finalize();
  351.  
  352.     area->attributes |= AS_AREA_ATTR_PARTIAL;
  353.     spinlock_unlock(&area->lock);
  354.  
  355.     /*
  356.      * Remove the empty area from address space.
  357.      */
  358.     btree_remove(&AS->as_area_btree, base, NULL);
  359.    
  360.     free(area);
  361.    
  362.     spinlock_unlock(&AS->lock);
  363.     interrupts_restore(ipl);
  364.     return 0;
  365. }
  366.  
  367. /** Send address space area to another task.
  368.  *
  369.  * Address space area is sent to the specified task.
  370.  * If the destination task is willing to accept the
  371.  * area, a new area is created according to the
  372.  * source area. Moreover, any existing mapping
  373.  * is copied as well, providing thus a mechanism
  374.  * for sharing group of pages. The source address
  375.  * space area and any associated mapping is preserved.
  376.  *
  377.  * @param dst_id Task ID of the accepting task.
  378.  * @param src_base Base address of the source address space area.
  379.  *
  380.  * @return Zero on success or ENOENT if there is no such task or
  381.  *     if there is no such address space area,
  382.  *     EPERM if there was a problem in accepting the area or
  383.  *     ENOMEM if there was a problem in allocating destination
  384.  *     address space area.
  385.  */
  386. int as_area_send(task_id_t dst_id, __address src_base)
  387. {
  388.     ipl_t ipl;
  389.     task_t *t;
  390.     count_t i;
  391.     as_t *dst_as;
  392.     __address dst_base;
  393.     int src_flags;
  394.     size_t src_size;
  395.     as_area_t *src_area, *dst_area;
  396.    
  397.     ipl = interrupts_disable();
  398.     spinlock_lock(&tasks_lock);
  399.    
  400.     t = task_find_by_id(dst_id);
  401.     if (!NULL) {
  402.         spinlock_unlock(&tasks_lock);
  403.         interrupts_restore(ipl);
  404.         return ENOENT;
  405.     }
  406.  
  407.     spinlock_lock(&t->lock);
  408.     spinlock_unlock(&tasks_lock);
  409.  
  410.     dst_as = t->as;
  411.     dst_base = (__address) t->accept_arg.base;
  412.    
  413.     if (dst_as == AS) {
  414.         /*
  415.          * The two tasks share the entire address space.
  416.          * Return error since there is no point in continuing.
  417.          */
  418.         spinlock_unlock(&t->lock);
  419.         interrupts_restore(ipl);
  420.         return EPERM;
  421.     }
  422.    
  423.     spinlock_lock(&AS->lock);
  424.     src_area = find_area_and_lock(AS, src_base);
  425.     if (!src_area) {
  426.         /*
  427.          * Could not find the source address space area.
  428.          */
  429.         spinlock_unlock(&t->lock);
  430.         spinlock_unlock(&AS->lock);
  431.         interrupts_restore(ipl);
  432.         return ENOENT;
  433.     }
  434.     src_size = src_area->pages * PAGE_SIZE;
  435.     src_flags = src_area->flags;
  436.     spinlock_unlock(&src_area->lock);
  437.     spinlock_unlock(&AS->lock);
  438.  
  439.     if ((t->accept_arg.task_id != TASK->taskid) || (t->accept_arg.size != src_size) ||
  440.         (t->accept_arg.flags != src_flags)) {
  441.         /*
  442.          * Discrepancy in either task ID, size or flags.
  443.          */
  444.         spinlock_unlock(&t->lock);
  445.         interrupts_restore(ipl);
  446.         return EPERM;
  447.     }
  448.    
  449.     /*
  450.      * Create copy of the source address space area.
  451.      * The destination area is created with AS_AREA_ATTR_PARTIAL
  452.      * attribute set which prevents race condition with
  453.      * preliminary as_page_fault() calls.
  454.      */
  455.     dst_area = as_area_create(dst_as, src_flags, src_size, dst_base, AS_AREA_ATTR_PARTIAL);
  456.     if (!dst_area) {
  457.         /*
  458.          * Destination address space area could not be created.
  459.          */
  460.         spinlock_unlock(&t->lock);
  461.         interrupts_restore(ipl);
  462.         return ENOMEM;
  463.     }
  464.    
  465.     memsetb((__address) &t->accept_arg, sizeof(as_area_acptsnd_arg_t), 0);
  466.     spinlock_unlock(&t->lock);
  467.    
  468.     /*
  469.      * Avoid deadlock by first locking the address space with lower address.
  470.      */
  471.     if (dst_as < AS) {
  472.         spinlock_lock(&dst_as->lock);
  473.         spinlock_lock(&AS->lock);
  474.     } else {
  475.         spinlock_lock(&AS->lock);
  476.         spinlock_lock(&dst_as->lock);
  477.     }
  478.    
  479.     for (i = 0; i < SIZE2FRAMES(src_size); i++) {
  480.         pte_t *pte;
  481.         __address frame;
  482.            
  483.         page_table_lock(AS, false);
  484.         pte = page_mapping_find(AS, src_base + i*PAGE_SIZE);
  485.         if (pte && PTE_VALID(pte)) {
  486.             ASSERT(PTE_PRESENT(pte));
  487.             frame = PTE_GET_FRAME(pte);
  488.             if (!(src_flags & AS_AREA_DEVICE))
  489.                 frame_reference_add(ADDR2PFN(frame));
  490.             page_table_unlock(AS, false);
  491.         } else {
  492.             page_table_unlock(AS, false);
  493.             continue;
  494.         }
  495.        
  496.         page_table_lock(dst_as, false);
  497.         page_mapping_insert(dst_as, dst_base + i*PAGE_SIZE, frame, area_flags_to_page_flags(src_flags));
  498.         page_table_unlock(dst_as, false);
  499.     }
  500.  
  501.     /*
  502.      * Now the destination address space area has been
  503.      * fully initialized. Clear the AS_AREA_ATTR_PARTIAL
  504.      * attribute.
  505.      */
  506.     spinlock_lock(&dst_area->lock);
  507.     dst_area->attributes &= ~AS_AREA_ATTR_PARTIAL;
  508.     spinlock_unlock(&dst_area->lock);
  509.    
  510.     spinlock_unlock(&AS->lock);
  511.     spinlock_unlock(&dst_as->lock);
  512.     interrupts_restore(ipl);
  513.    
  514.     return 0;
  515. }
  516.  
  517. /** Initialize mapping for one page of address space.
  518.  *
  519.  * This functions maps 'page' to 'frame' according
  520.  * to attributes of the address space area to
  521.  * wich 'page' belongs.
  522.  *
  523.  * @param as Target address space.
  524.  * @param page Virtual page within the area.
  525.  * @param frame Physical frame to which page will be mapped.
  526.  */
  527. void as_set_mapping(as_t *as, __address page, __address frame)
  528. {
  529.     as_area_t *area;
  530.     ipl_t ipl;
  531.    
  532.     ipl = interrupts_disable();
  533.     page_table_lock(as, true);
  534.    
  535.     area = find_area_and_lock(as, page);
  536.     if (!area) {
  537.         panic("page not part of any as_area\n");
  538.     }
  539.  
  540.     page_mapping_insert(as, page, frame, get_area_flags(area));
  541.    
  542.     spinlock_unlock(&area->lock);
  543.     page_table_unlock(as, true);
  544.     interrupts_restore(ipl);
  545. }
  546.  
  547. /** Handle page fault within the current address space.
  548.  *
  549.  * This is the high-level page fault handler.
  550.  * Interrupts are assumed disabled.
  551.  *
  552.  * @param page Faulting page.
  553.  * @param istate Pointer to interrupted state.
  554.  *
  555.  * @return 0 on page fault, 1 on success or 2 if the fault was caused by copy_to_uspace() or copy_from_uspace().
  556.  */
  557. int as_page_fault(__address page, istate_t *istate)
  558. {
  559.     pte_t *pte;
  560.     as_area_t *area;
  561.     __address frame;
  562.    
  563.     ASSERT(AS);
  564.  
  565.     spinlock_lock(&AS->lock);
  566.     area = find_area_and_lock(AS, page);   
  567.     if (!area) {
  568.         /*
  569.          * No area contained mapping for 'page'.
  570.          * Signal page fault to low-level handler.
  571.          */
  572.         spinlock_unlock(&AS->lock);
  573.         goto page_fault;
  574.     }
  575.  
  576.     if (area->attributes & AS_AREA_ATTR_PARTIAL) {
  577.         /*
  578.          * The address space area is not fully initialized.
  579.          * Avoid possible race by returning error.
  580.          */
  581.         spinlock_unlock(&area->lock);
  582.         spinlock_unlock(&AS->lock);
  583.         goto page_fault;       
  584.     }
  585.  
  586.     ASSERT(!(area->flags & AS_AREA_DEVICE));
  587.  
  588.     page_table_lock(AS, false);
  589.    
  590.     /*
  591.      * To avoid race condition between two page faults
  592.      * on the same address, we need to make sure
  593.      * the mapping has not been already inserted.
  594.      */
  595.     if ((pte = page_mapping_find(AS, page))) {
  596.         if (PTE_PRESENT(pte)) {
  597.             page_table_unlock(AS, false);
  598.             spinlock_unlock(&area->lock);
  599.             spinlock_unlock(&AS->lock);
  600.             return 1;
  601.         }
  602.     }
  603.  
  604.     /*
  605.      * In general, there can be several reasons that
  606.      * can have caused this fault.
  607.      *
  608.      * - non-existent mapping: the area is a scratch
  609.      *   area (e.g. stack) and so far has not been
  610.      *   allocated a frame for the faulting page
  611.      *
  612.      * - non-present mapping: another possibility,
  613.      *   currently not implemented, would be frame
  614.      *   reuse; when this becomes a possibility,
  615.      *   do not forget to distinguish between
  616.      *   the different causes
  617.      */
  618.     frame = PFN2ADDR(frame_alloc(ONE_FRAME, 0));
  619.     memsetb(PA2KA(frame), FRAME_SIZE, 0);
  620.    
  621.     /*
  622.      * Map 'page' to 'frame'.
  623.      * Note that TLB shootdown is not attempted as only new information is being
  624.      * inserted into page tables.
  625.      */
  626.     page_mapping_insert(AS, page, frame, get_area_flags(area));
  627.     page_table_unlock(AS, false);
  628.    
  629.     spinlock_unlock(&area->lock);
  630.     spinlock_unlock(&AS->lock);
  631.     return AS_PF_OK;
  632.  
  633. page_fault:
  634.     if (!THREAD)
  635.         return AS_PF_FAULT;
  636.    
  637.     if (THREAD->in_copy_from_uspace) {
  638.         THREAD->in_copy_from_uspace = false;
  639.         istate_set_retaddr(istate, (__address) &memcpy_from_uspace_failover_address);
  640.     } else if (THREAD->in_copy_to_uspace) {
  641.         THREAD->in_copy_to_uspace = false;
  642.         istate_set_retaddr(istate, (__address) &memcpy_to_uspace_failover_address);
  643.     } else {
  644.         return AS_PF_FAULT;
  645.     }
  646.  
  647.     return AS_PF_DEFER;
  648. }
  649.  
  650. /** Switch address spaces.
  651.  *
  652.  * @param old Old address space or NULL.
  653.  * @param new New address space.
  654.  */
  655. void as_switch(as_t *old, as_t *new)
  656. {
  657.     ipl_t ipl;
  658.     bool needs_asid = false;
  659.    
  660.     ipl = interrupts_disable();
  661.     spinlock_lock(&as_lock);
  662.  
  663.     /*
  664.      * First, take care of the old address space.
  665.      */
  666.     if (old) {
  667.         spinlock_lock(&old->lock);
  668.         ASSERT(old->refcount);
  669.         if((--old->refcount == 0) && (old != AS_KERNEL)) {
  670.             /*
  671.              * The old address space is no longer active on
  672.              * any processor. It can be appended to the
  673.              * list of inactive address spaces with assigned
  674.              * ASID.
  675.              */
  676.              ASSERT(old->asid != ASID_INVALID);
  677.              list_append(&old->inactive_as_with_asid_link, &inactive_as_with_asid_head);
  678.         }
  679.         spinlock_unlock(&old->lock);
  680.     }
  681.  
  682.     /*
  683.      * Second, prepare the new address space.
  684.      */
  685.     spinlock_lock(&new->lock);
  686.     if ((new->refcount++ == 0) && (new != AS_KERNEL)) {
  687.         if (new->asid != ASID_INVALID)
  688.             list_remove(&new->inactive_as_with_asid_link);
  689.         else
  690.             needs_asid = true;  /* defer call to asid_get() until new->lock is released */
  691.     }
  692.     SET_PTL0_ADDRESS(new->page_table);
  693.     spinlock_unlock(&new->lock);
  694.  
  695.     if (needs_asid) {
  696.         /*
  697.          * Allocation of new ASID was deferred
  698.          * until now in order to avoid deadlock.
  699.          */
  700.         asid_t asid;
  701.        
  702.         asid = asid_get();
  703.         spinlock_lock(&new->lock);
  704.         new->asid = asid;
  705.         spinlock_unlock(&new->lock);
  706.     }
  707.     spinlock_unlock(&as_lock);
  708.     interrupts_restore(ipl);
  709.    
  710.     /*
  711.      * Perform architecture-specific steps.
  712.      * (e.g. write ASID to hardware register etc.)
  713.      */
  714.     as_install_arch(new);
  715.    
  716.     AS = new;
  717. }
  718.  
  719. /** Convert address space area flags to page flags.
  720.  *
  721.  * @param aflags Flags of some address space area.
  722.  *
  723.  * @return Flags to be passed to page_mapping_insert().
  724.  */
  725. int area_flags_to_page_flags(int aflags)
  726. {
  727.     int flags;
  728.  
  729.     flags = PAGE_USER | PAGE_PRESENT;
  730.    
  731.     if (aflags & AS_AREA_READ)
  732.         flags |= PAGE_READ;
  733.        
  734.     if (aflags & AS_AREA_WRITE)
  735.         flags |= PAGE_WRITE;
  736.    
  737.     if (aflags & AS_AREA_EXEC)
  738.         flags |= PAGE_EXEC;
  739.    
  740.     if (!(aflags & AS_AREA_DEVICE))
  741.         flags |= PAGE_CACHEABLE;
  742.        
  743.     return flags;
  744. }
  745.  
  746. /** Compute flags for virtual address translation subsytem.
  747.  *
  748.  * The address space area must be locked.
  749.  * Interrupts must be disabled.
  750.  *
  751.  * @param a Address space area.
  752.  *
  753.  * @return Flags to be used in page_mapping_insert().
  754.  */
  755. int get_area_flags(as_area_t *a)
  756. {
  757.     return area_flags_to_page_flags(a->flags);
  758. }
  759.  
  760. /** Create page table.
  761.  *
  762.  * Depending on architecture, create either address space
  763.  * private or global page table.
  764.  *
  765.  * @param flags Flags saying whether the page table is for kernel address space.
  766.  *
  767.  * @return First entry of the page table.
  768.  */
  769. pte_t *page_table_create(int flags)
  770. {
  771.         ASSERT(as_operations);
  772.         ASSERT(as_operations->page_table_create);
  773.  
  774.         return as_operations->page_table_create(flags);
  775. }
  776.  
  777. /** Lock page table.
  778.  *
  779.  * This function should be called before any page_mapping_insert(),
  780.  * page_mapping_remove() and page_mapping_find().
  781.  *
  782.  * Locking order is such that address space areas must be locked
  783.  * prior to this call. Address space can be locked prior to this
  784.  * call in which case the lock argument is false.
  785.  *
  786.  * @param as Address space.
  787.  * @param lock If false, do not attempt to lock as->lock.
  788.  */
  789. void page_table_lock(as_t *as, bool lock)
  790. {
  791.     ASSERT(as_operations);
  792.     ASSERT(as_operations->page_table_lock);
  793.  
  794.     as_operations->page_table_lock(as, lock);
  795. }
  796.  
  797. /** Unlock page table.
  798.  *
  799.  * @param as Address space.
  800.  * @param unlock If false, do not attempt to unlock as->lock.
  801.  */
  802. void page_table_unlock(as_t *as, bool unlock)
  803. {
  804.     ASSERT(as_operations);
  805.     ASSERT(as_operations->page_table_unlock);
  806.  
  807.     as_operations->page_table_unlock(as, unlock);
  808. }
  809.  
  810.  
  811. /** Find address space area and lock it.
  812.  *
  813.  * The address space must be locked and interrupts must be disabled.
  814.  *
  815.  * @param as Address space.
  816.  * @param va Virtual address.
  817.  *
  818.  * @return Locked address space area containing va on success or NULL on failure.
  819.  */
  820. as_area_t *find_area_and_lock(as_t *as, __address va)
  821. {
  822.     as_area_t *a;
  823.     btree_node_t *leaf, *lnode;
  824.     int i;
  825.    
  826.     a = (as_area_t *) btree_search(&as->as_area_btree, va, &leaf);
  827.     if (a) {
  828.         /* va is the base address of an address space area */
  829.         spinlock_lock(&a->lock);
  830.         return a;
  831.     }
  832.    
  833.     /*
  834.      * Search the leaf node and the righmost record of its left neighbour
  835.      * to find out whether this is a miss or va belongs to an address
  836.      * space area found there.
  837.      */
  838.    
  839.     /* First, search the leaf node itself. */
  840.     for (i = 0; i < leaf->keys; i++) {
  841.         a = (as_area_t *) leaf->value[i];
  842.         spinlock_lock(&a->lock);
  843.         if ((a->base <= va) && (va < a->base + a->pages * PAGE_SIZE)) {
  844.             return a;
  845.         }
  846.         spinlock_unlock(&a->lock);
  847.     }
  848.  
  849.     /*
  850.      * Second, locate the left neighbour and test its last record.
  851.      * Because of its position in the B+tree, it must have base < va.
  852.      */
  853.     if ((lnode = btree_leaf_node_left_neighbour(&as->as_area_btree, leaf))) {
  854.         a = (as_area_t *) lnode->value[lnode->keys - 1];
  855.         spinlock_lock(&a->lock);
  856.         if (va < a->base + a->pages * PAGE_SIZE) {
  857.             return a;
  858.         }
  859.         spinlock_unlock(&a->lock);
  860.     }
  861.  
  862.     return NULL;
  863. }
  864.  
  865. /** Check area conflicts with other areas.
  866.  *
  867.  * The address space must be locked and interrupts must be disabled.
  868.  *
  869.  * @param as Address space.
  870.  * @param va Starting virtual address of the area being tested.
  871.  * @param size Size of the area being tested.
  872.  * @param avoid_area Do not touch this area.
  873.  *
  874.  * @return True if there is no conflict, false otherwise.
  875.  */
  876. bool check_area_conflicts(as_t *as, __address va, size_t size, as_area_t *avoid_area)
  877. {
  878.     as_area_t *a;
  879.     btree_node_t *leaf, *node;
  880.     int i;
  881.    
  882.     /*
  883.      * We don't want any area to have conflicts with NULL page.
  884.      */
  885.     if (overlaps(va, size, NULL, PAGE_SIZE))
  886.         return false;
  887.    
  888.     /*
  889.      * The leaf node is found in O(log n), where n is proportional to
  890.      * the number of address space areas belonging to as.
  891.      * The check for conflicts is then attempted on the rightmost
  892.      * record in the left neighbour, the leftmost record in the right
  893.      * neighbour and all records in the leaf node itself.
  894.      */
  895.    
  896.     if ((a = (as_area_t *) btree_search(&as->as_area_btree, va, &leaf))) {
  897.         if (a != avoid_area)
  898.             return false;
  899.     }
  900.    
  901.     /* First, check the two border cases. */
  902.     if ((node = btree_leaf_node_left_neighbour(&as->as_area_btree, leaf))) {
  903.         a = (as_area_t *) node->value[node->keys - 1];
  904.         spinlock_lock(&a->lock);
  905.         if (overlaps(va, size, a->base, a->pages * PAGE_SIZE)) {
  906.             spinlock_unlock(&a->lock);
  907.             return false;
  908.         }
  909.         spinlock_unlock(&a->lock);
  910.     }
  911.     if ((node = btree_leaf_node_right_neighbour(&as->as_area_btree, leaf))) {
  912.         a = (as_area_t *) node->value[0];
  913.         spinlock_lock(&a->lock);
  914.         if (overlaps(va, size, a->base, a->pages * PAGE_SIZE)) {
  915.             spinlock_unlock(&a->lock);
  916.             return false;
  917.         }
  918.         spinlock_unlock(&a->lock);
  919.     }
  920.    
  921.     /* Second, check the leaf node. */
  922.     for (i = 0; i < leaf->keys; i++) {
  923.         a = (as_area_t *) leaf->value[i];
  924.    
  925.         if (a == avoid_area)
  926.             continue;
  927.    
  928.         spinlock_lock(&a->lock);
  929.         if (overlaps(va, size, a->base, a->pages * PAGE_SIZE)) {
  930.             spinlock_unlock(&a->lock);
  931.             return false;
  932.         }
  933.         spinlock_unlock(&a->lock);
  934.     }
  935.  
  936.     /*
  937.      * So far, the area does not conflict with other areas.
  938.      * Check if it doesn't conflict with kernel address space.
  939.      */  
  940.     if (!KERNEL_ADDRESS_SPACE_SHADOWED) {
  941.         return !overlaps(va, size,
  942.             KERNEL_ADDRESS_SPACE_START, KERNEL_ADDRESS_SPACE_END-KERNEL_ADDRESS_SPACE_START);
  943.     }
  944.  
  945.     return true;
  946. }
  947.  
  948. /*
  949.  * Address space related syscalls.
  950.  */
  951.  
  952. /** Wrapper for as_area_create(). */
  953. __native sys_as_area_create(__address address, size_t size, int flags)
  954. {
  955.     if (as_area_create(AS, flags, size, address, AS_AREA_ATTR_NONE))
  956.         return (__native) address;
  957.     else
  958.         return (__native) -1;
  959. }
  960.  
  961. /** Wrapper for as_area_resize. */
  962. __native sys_as_area_resize(__address address, size_t size, int flags)
  963. {
  964.     return (__native) as_area_resize(AS, address, size, 0);
  965. }
  966.  
  967. /** Wrapper for as_area_destroy. */
  968. __native sys_as_area_destroy(__address address)
  969. {
  970.     return (__native) as_area_destroy(AS, address);
  971. }
  972.  
  973. /** Prepare task for accepting address space area from another task.
  974.  *
  975.  * @param uspace_accept_arg Accept structure passed from userspace.
  976.  *
  977.  * @return EPERM if the task ID encapsulated in @uspace_accept_arg references
  978.  *     TASK. Otherwise zero is returned.
  979.  */
  980. __native sys_as_area_accept(as_area_acptsnd_arg_t *uspace_accept_arg)
  981. {
  982.     as_area_acptsnd_arg_t arg;
  983.     int rc;
  984.    
  985.     rc = copy_from_uspace(&arg, uspace_accept_arg, sizeof(as_area_acptsnd_arg_t));
  986.     if (rc != 0)
  987.         return rc;
  988.    
  989.     if (!arg.size)
  990.         return (__native) EPERM;
  991.    
  992.     if (arg.task_id == TASK->taskid) {
  993.         /*
  994.          * Accepting from itself is not allowed.
  995.          */
  996.         return (__native) EPERM;
  997.     }
  998.    
  999.     memcpy(&TASK->accept_arg, &arg, sizeof(as_area_acptsnd_arg_t));
  1000.    
  1001.         return 0;
  1002. }
  1003.  
  1004. /** Wrapper for as_area_send. */
  1005. __native sys_as_area_send(as_area_acptsnd_arg_t *uspace_send_arg)
  1006. {
  1007.     as_area_acptsnd_arg_t arg;
  1008.     int rc;
  1009.    
  1010.     rc = copy_from_uspace(&arg, uspace_send_arg, sizeof(as_area_acptsnd_arg_t));
  1011.     if (rc != 0)
  1012.         return rc;
  1013.  
  1014.     if (!arg.size)
  1015.         return (__native) EPERM;
  1016.    
  1017.     if (arg.task_id == TASK->taskid) {
  1018.         /*
  1019.          * Sending to itself is not allowed.
  1020.          */
  1021.         return (__native) EPERM;
  1022.     }
  1023.  
  1024.     return (__native) as_area_send(arg.task_id, (__address) arg.base);
  1025. }
  1026.