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