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  1. /*
  2.  * Copyright (C) 2001-2006 Jakub Jermar
  3.  * All rights reserved.
  4.  *
  5.  * Redistribution and use in source and binary forms, with or without
  6.  * modification, are permitted provided that the following conditions
  7.  * are met:
  8.  *
  9.  * - Redistributions of source code must retain the above copyright
  10.  *   notice, this list of conditions and the following disclaimer.
  11.  * - Redistributions in binary form must reproduce the above copyright
  12.  *   notice, this list of conditions and the following disclaimer in the
  13.  *   documentation and/or other materials provided with the distribution.
  14.  * - The name of the author may not be used to endorse or promote products
  15.  *   derived from this software without specific prior written permission.
  16.  *
  17.  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
  18.  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
  19.  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
  20.  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
  21.  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
  22.  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  23.  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  24.  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  25.  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
  26.  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  27.  */
  28.  
  29. /**
  30.  * @file    as.c
  31.  * @brief   Address space related functions.
  32.  *
  33.  * This file contains address space manipulation functions.
  34.  * Roughly speaking, this is a higher-level client of
  35.  * Virtual Address Translation (VAT) subsystem.
  36.  *
  37.  * Functionality provided by this file allows one to
  38.  * create address space and create, resize and share
  39.  * address space areas.
  40.  *
  41.  * @see page.c
  42.  *
  43.  */
  44.  
  45. #include <mm/as.h>
  46. #include <arch/mm/as.h>
  47. #include <mm/page.h>
  48. #include <mm/frame.h>
  49. #include <mm/slab.h>
  50. #include <mm/tlb.h>
  51. #include <arch/mm/page.h>
  52. #include <genarch/mm/page_pt.h>
  53. #include <genarch/mm/page_ht.h>
  54. #include <mm/asid.h>
  55. #include <arch/mm/asid.h>
  56. #include <synch/spinlock.h>
  57. #include <synch/mutex.h>
  58. #include <adt/list.h>
  59. #include <adt/btree.h>
  60. #include <proc/task.h>
  61. #include <proc/thread.h>
  62. #include <arch/asm.h>
  63. #include <panic.h>
  64. #include <debug.h>
  65. #include <print.h>
  66. #include <memstr.h>
  67. #include <macros.h>
  68. #include <arch.h>
  69. #include <errno.h>
  70. #include <config.h>
  71. #include <arch/types.h>
  72. #include <typedefs.h>
  73. #include <syscall/copy.h>
  74. #include <arch/interrupt.h>
  75.  
  76. as_operations_t *as_operations = NULL;
  77.  
  78. /** Address space lock. It protects inactive_as_with_asid_head. Must be acquired before as_t mutex. */
  79. SPINLOCK_INITIALIZE(as_lock);
  80.  
  81. /**
  82.  * This list contains address spaces that are not active on any
  83.  * processor and that have valid ASID.
  84.  */
  85. LIST_INITIALIZE(inactive_as_with_asid_head);
  86.  
  87. /** Kernel address space. */
  88. as_t *AS_KERNEL = NULL;
  89.  
  90. static int area_flags_to_page_flags(int aflags);
  91. static int get_area_flags(as_area_t *a);
  92. static as_area_t *find_area_and_lock(as_t *as, __address va);
  93. static bool check_area_conflicts(as_t *as, __address va, size_t size, as_area_t *avoid_area);
  94.  
  95. /** Initialize address space subsystem. */
  96. void as_init(void)
  97. {
  98.     as_arch_init();
  99.     AS_KERNEL = as_create(FLAG_AS_KERNEL);
  100.         if (!AS_KERNEL)
  101.                 panic("can't create kernel address space\n");
  102. }
  103.  
  104. /** Create address space.
  105.  *
  106.  * @param flags Flags that influence way in wich the address space is created.
  107.  */
  108. as_t *as_create(int flags)
  109. {
  110.     as_t *as;
  111.  
  112.     as = (as_t *) malloc(sizeof(as_t), 0);
  113.     link_initialize(&as->inactive_as_with_asid_link);
  114.     mutex_initialize(&as->lock);
  115.     btree_create(&as->as_area_btree);
  116.    
  117.     if (flags & FLAG_AS_KERNEL)
  118.         as->asid = ASID_KERNEL;
  119.     else
  120.         as->asid = ASID_INVALID;
  121.    
  122.     as->refcount = 0;
  123.     as->page_table = page_table_create(flags);
  124.  
  125.     return as;
  126. }
  127.  
  128. /** Free Adress space */
  129. void as_free(as_t *as)
  130. {
  131.     ASSERT(as->refcount == 0);
  132.  
  133.     /* TODO: free as_areas and other resources held by as */
  134.     /* TODO: free page table */
  135.     free(as);
  136. }
  137.  
  138. /** Create address space area of common attributes.
  139.  *
  140.  * The created address space area is added to the target address space.
  141.  *
  142.  * @param as Target address space.
  143.  * @param flags Flags of the area memory.
  144.  * @param size Size of area.
  145.  * @param base Base address of area.
  146.  * @param attrs Attributes of the area.
  147.  *
  148.  * @return Address space area on success or NULL on failure.
  149.  */
  150. as_area_t *as_area_create(as_t *as, int flags, size_t size, __address base, int attrs)
  151. {
  152.     ipl_t ipl;
  153.     as_area_t *a;
  154.    
  155.     if (base % PAGE_SIZE)
  156.         return NULL;
  157.  
  158.     if (!size)
  159.         return NULL;
  160.  
  161.     /* Writeable executable areas are not supported. */
  162.     if ((flags & AS_AREA_EXEC) && (flags & AS_AREA_WRITE))
  163.         return NULL;
  164.    
  165.     ipl = interrupts_disable();
  166.     mutex_lock(&as->lock);
  167.    
  168.     if (!check_area_conflicts(as, base, size, NULL)) {
  169.         mutex_unlock(&as->lock);
  170.         interrupts_restore(ipl);
  171.         return NULL;
  172.     }
  173.    
  174.     a = (as_area_t *) malloc(sizeof(as_area_t), 0);
  175.  
  176.     mutex_initialize(&a->lock);
  177.    
  178.     a->flags = flags;
  179.     a->attributes = attrs;
  180.     a->pages = SIZE2FRAMES(size);
  181.     a->base = base;
  182.    
  183.     btree_insert(&as->as_area_btree, base, (void *) a, NULL);
  184.  
  185.     mutex_unlock(&as->lock);
  186.     interrupts_restore(ipl);
  187.  
  188.     return a;
  189. }
  190.  
  191. /** Find address space area and change it.
  192.  *
  193.  * @param as Address space.
  194.  * @param address Virtual address belonging to the area to be changed. Must be page-aligned.
  195.  * @param size New size of the virtual memory block starting at address.
  196.  * @param flags Flags influencing the remap operation. Currently unused.
  197.  *
  198.  * @return Zero on success or a value from @ref errno.h otherwise.
  199.  */
  200. int as_area_resize(as_t *as, __address address, size_t size, int flags)
  201. {
  202.     as_area_t *area;
  203.     ipl_t ipl;
  204.     size_t pages;
  205.    
  206.     ipl = interrupts_disable();
  207.     mutex_lock(&as->lock);
  208.    
  209.     /*
  210.      * Locate the area.
  211.      */
  212.     area = find_area_and_lock(as, address);
  213.     if (!area) {
  214.         mutex_unlock(&as->lock);
  215.         interrupts_restore(ipl);
  216.         return ENOENT;
  217.     }
  218.  
  219.     if (area->flags & AS_AREA_DEVICE) {
  220.         /*
  221.          * Remapping of address space areas associated
  222.          * with memory mapped devices is not supported.
  223.          */
  224.         mutex_unlock(&area->lock);
  225.         mutex_unlock(&as->lock);
  226.         interrupts_restore(ipl);
  227.         return ENOTSUP;
  228.     }
  229.  
  230.     pages = SIZE2FRAMES((address - area->base) + size);
  231.     if (!pages) {
  232.         /*
  233.          * Zero size address space areas are not allowed.
  234.          */
  235.         mutex_unlock(&area->lock);
  236.         mutex_unlock(&as->lock);
  237.         interrupts_restore(ipl);
  238.         return EPERM;
  239.     }
  240.    
  241.     if (pages < area->pages) {
  242.         int i;
  243.  
  244.         /*
  245.          * Shrinking the area.
  246.          * No need to check for overlaps.
  247.          */
  248.         for (i = pages; i < area->pages; i++) {
  249.             pte_t *pte;
  250.            
  251.             /*
  252.              * Releasing physical memory.
  253.              * This depends on the fact that the memory was allocated using frame_alloc().
  254.              */
  255.             page_table_lock(as, false);
  256.             pte = page_mapping_find(as, area->base + i*PAGE_SIZE);
  257.             if (pte && PTE_VALID(pte)) {
  258.                 __address frame;
  259.  
  260.                 ASSERT(PTE_PRESENT(pte));
  261.                 frame = PTE_GET_FRAME(pte);
  262.                 page_mapping_remove(as, area->base + i*PAGE_SIZE);
  263.                 page_table_unlock(as, false);
  264.  
  265.                 frame_free(ADDR2PFN(frame));
  266.             } else {
  267.                 page_table_unlock(as, false);
  268.             }
  269.         }
  270.         /*
  271.          * Invalidate TLB's.
  272.          */
  273.         tlb_shootdown_start(TLB_INVL_PAGES, AS->asid, area->base + pages*PAGE_SIZE, area->pages - pages);
  274.         tlb_invalidate_pages(AS->asid, area->base + pages*PAGE_SIZE, area->pages - pages);
  275.         tlb_shootdown_finalize();
  276.     } else {
  277.         /*
  278.          * Growing the area.
  279.          * Check for overlaps with other address space areas.
  280.          */
  281.         if (!check_area_conflicts(as, address, pages * PAGE_SIZE, area)) {
  282.             mutex_unlock(&area->lock);
  283.             mutex_unlock(&as->lock);       
  284.             interrupts_restore(ipl);
  285.             return EADDRNOTAVAIL;
  286.         }
  287.     }
  288.  
  289.     area->pages = pages;
  290.    
  291.     mutex_unlock(&area->lock);
  292.     mutex_unlock(&as->lock);
  293.     interrupts_restore(ipl);
  294.  
  295.     return 0;
  296. }
  297.  
  298. /** Destroy address space area.
  299.  *
  300.  * @param as Address space.
  301.  * @param address Address withing the area to be deleted.
  302.  *
  303.  * @return Zero on success or a value from @ref errno.h on failure.
  304.  */
  305. int as_area_destroy(as_t *as, __address address)
  306. {
  307.     as_area_t *area;
  308.     __address base;
  309.     ipl_t ipl;
  310.     int i;
  311.  
  312.     ipl = interrupts_disable();
  313.     mutex_lock(&as->lock);
  314.  
  315.     area = find_area_and_lock(as, address);
  316.     if (!area) {
  317.         mutex_unlock(&as->lock);
  318.         interrupts_restore(ipl);
  319.         return ENOENT;
  320.     }
  321.  
  322.     base = area->base; 
  323.     for (i = 0; i < area->pages; i++) {
  324.         pte_t *pte;
  325.  
  326.         /*
  327.          * Releasing physical memory.
  328.          * Areas mapping memory-mapped devices are treated differently than
  329.          * areas backing frame_alloc()'ed memory.
  330.          */
  331.         page_table_lock(as, false);
  332.         pte = page_mapping_find(as, area->base + i*PAGE_SIZE);
  333.         if (pte && PTE_VALID(pte)) {
  334.             ASSERT(PTE_PRESENT(pte));
  335.             page_mapping_remove(as, area->base + i*PAGE_SIZE);
  336.             if (area->flags & AS_AREA_DEVICE) {
  337.                 __address frame;
  338.                 frame = PTE_GET_FRAME(pte);
  339.                 frame_free(ADDR2PFN(frame));
  340.             }
  341.             page_table_unlock(as, false);
  342.         } else {
  343.             page_table_unlock(as, false);
  344.         }
  345.     }
  346.     /*
  347.      * Invalidate TLB's.
  348.      */
  349.     tlb_shootdown_start(TLB_INVL_PAGES, AS->asid, area->base, area->pages);
  350.     tlb_invalidate_pages(AS->asid, area->base, area->pages);
  351.     tlb_shootdown_finalize();
  352.  
  353.     area->attributes |= AS_AREA_ATTR_PARTIAL;
  354.     mutex_unlock(&area->lock);
  355.  
  356.     /*
  357.      * Remove the empty area from address space.
  358.      */
  359.     btree_remove(&AS->as_area_btree, base, NULL);
  360.    
  361.     free(area);
  362.    
  363.     mutex_unlock(&AS->lock);
  364.     interrupts_restore(ipl);
  365.     return 0;
  366. }
  367.  
  368. /** Steal address space area from another task.
  369.  *
  370.  * Address space area is stolen from another task
  371.  * Moreover, any existing mapping
  372.  * is copied as well, providing thus a mechanism
  373.  * for sharing group of pages. The source address
  374.  * space area and any associated mapping is preserved.
  375.  *
  376.  * @param src_task Pointer of source task
  377.  * @param src_base Base address of the source address space area.
  378.  * @param acc_size Expected size of the source area
  379.  * @param dst_base Target base address
  380.  *
  381.  * @return Zero on success or ENOENT if there is no such task or
  382.  *     if there is no such address space area,
  383.  *     EPERM if there was a problem in accepting the area or
  384.  *     ENOMEM if there was a problem in allocating destination
  385.  *     address space area.
  386.  */
  387. int as_area_steal(task_t *src_task, __address src_base, size_t acc_size,
  388.           __address dst_base)
  389. {
  390.     ipl_t ipl;
  391.     count_t i;
  392.     as_t *src_as;      
  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(&src_task->lock);
  399.     src_as = src_task->as;
  400.    
  401.     mutex_lock(&src_as->lock);
  402.     src_area = find_area_and_lock(src_as, src_base);
  403.     if (!src_area) {
  404.         /*
  405.          * Could not find the source address space area.
  406.          */
  407.         spinlock_unlock(&src_task->lock);
  408.         mutex_unlock(&src_as->lock);
  409.         interrupts_restore(ipl);
  410.         return ENOENT;
  411.     }
  412.     src_size = src_area->pages * PAGE_SIZE;
  413.     src_flags = src_area->flags;
  414.     mutex_unlock(&src_area->lock);
  415.     mutex_unlock(&src_as->lock);
  416.  
  417.  
  418.     if (src_size != acc_size) {
  419.         spinlock_unlock(&src_task->lock);
  420.         interrupts_restore(ipl);
  421.         return EPERM;
  422.     }
  423.     /*
  424.      * Create copy of the source address space area.
  425.      * The destination area is created with AS_AREA_ATTR_PARTIAL
  426.      * attribute set which prevents race condition with
  427.      * preliminary as_page_fault() calls.
  428.      */
  429.     dst_area = as_area_create(AS, src_flags, src_size, dst_base, AS_AREA_ATTR_PARTIAL);
  430.     if (!dst_area) {
  431.         /*
  432.          * Destination address space area could not be created.
  433.          */
  434.         spinlock_unlock(&src_task->lock);
  435.         interrupts_restore(ipl);
  436.         return ENOMEM;
  437.     }
  438.    
  439.     spinlock_unlock(&src_task->lock);
  440.    
  441.     /*
  442.      * Avoid deadlock by first locking the address space with lower address.
  443.      */
  444.     if (AS < src_as) {
  445.         mutex_lock(&AS->lock);
  446.         mutex_lock(&src_as->lock);
  447.     } else {
  448.         mutex_lock(&AS->lock);
  449.         mutex_lock(&src_as->lock);
  450.     }
  451.    
  452.     for (i = 0; i < SIZE2FRAMES(src_size); i++) {
  453.         pte_t *pte;
  454.         __address frame;
  455.            
  456.         page_table_lock(src_as, false);
  457.         pte = page_mapping_find(src_as, src_base + i*PAGE_SIZE);
  458.         if (pte && PTE_VALID(pte)) {
  459.             ASSERT(PTE_PRESENT(pte));
  460.             frame = PTE_GET_FRAME(pte);
  461.             if (!(src_flags & AS_AREA_DEVICE))
  462.                 frame_reference_add(ADDR2PFN(frame));
  463.             page_table_unlock(src_as, false);
  464.         } else {
  465.             page_table_unlock(src_as, false);
  466.             continue;
  467.         }
  468.        
  469.         page_table_lock(AS, false);
  470.         page_mapping_insert(AS, dst_base + i*PAGE_SIZE, frame, area_flags_to_page_flags(src_flags));
  471.         page_table_unlock(AS, false);
  472.     }
  473.  
  474.     /*
  475.      * Now the destination address space area has been
  476.      * fully initialized. Clear the AS_AREA_ATTR_PARTIAL
  477.      * attribute.
  478.      */
  479.     mutex_lock(&dst_area->lock);
  480.     dst_area->attributes &= ~AS_AREA_ATTR_PARTIAL;
  481.     mutex_unlock(&dst_area->lock);
  482.    
  483.     mutex_unlock(&AS->lock);
  484.     mutex_unlock(&src_as->lock);
  485.     interrupts_restore(ipl);
  486.    
  487.     return 0;
  488. }
  489.  
  490. /** Initialize mapping for one page of address space.
  491.  *
  492.  * This functions maps 'page' to 'frame' according
  493.  * to attributes of the address space area to
  494.  * wich 'page' belongs.
  495.  *
  496.  * @param as Target address space.
  497.  * @param page Virtual page within the area.
  498.  * @param frame Physical frame to which page will be mapped.
  499.  */
  500. void as_set_mapping(as_t *as, __address page, __address frame)
  501. {
  502.     as_area_t *area;
  503.     ipl_t ipl;
  504.    
  505.     ipl = interrupts_disable();
  506.     page_table_lock(as, true);
  507.    
  508.     area = find_area_and_lock(as, page);
  509.     if (!area) {
  510.         panic("page not part of any as_area\n");
  511.     }
  512.  
  513.     page_mapping_insert(as, page, frame, get_area_flags(area));
  514.    
  515.     mutex_unlock(&area->lock);
  516.     page_table_unlock(as, true);
  517.     interrupts_restore(ipl);
  518. }
  519.  
  520. /** Handle page fault within the current address space.
  521.  *
  522.  * This is the high-level page fault handler.
  523.  * Interrupts are assumed disabled.
  524.  *
  525.  * @param page Faulting page.
  526.  * @param istate Pointer to interrupted state.
  527.  *
  528.  * @return 0 on page fault, 1 on success or 2 if the fault was caused by copy_to_uspace() or copy_from_uspace().
  529.  */
  530. int as_page_fault(__address page, istate_t *istate)
  531. {
  532.     pte_t *pte;
  533.     as_area_t *area;
  534.     __address frame;
  535.    
  536.     if (!THREAD)
  537.         return 0;
  538.        
  539.     ASSERT(AS);
  540.  
  541.     mutex_lock(&AS->lock);
  542.     area = find_area_and_lock(AS, page);   
  543.     if (!area) {
  544.         /*
  545.          * No area contained mapping for 'page'.
  546.          * Signal page fault to low-level handler.
  547.          */
  548.         mutex_unlock(&AS->lock);
  549.         goto page_fault;
  550.     }
  551.  
  552.     if (area->attributes & AS_AREA_ATTR_PARTIAL) {
  553.         /*
  554.          * The address space area is not fully initialized.
  555.          * Avoid possible race by returning error.
  556.          */
  557.         mutex_unlock(&area->lock);
  558.         mutex_unlock(&AS->lock);
  559.         goto page_fault;       
  560.     }
  561.  
  562.     ASSERT(!(area->flags & AS_AREA_DEVICE));
  563.  
  564.     page_table_lock(AS, false);
  565.    
  566.     /*
  567.      * To avoid race condition between two page faults
  568.      * on the same address, we need to make sure
  569.      * the mapping has not been already inserted.
  570.      */
  571.     if ((pte = page_mapping_find(AS, page))) {
  572.         if (PTE_PRESENT(pte)) {
  573.             page_table_unlock(AS, false);
  574.             mutex_unlock(&area->lock);
  575.             mutex_unlock(&AS->lock);
  576.             return 1;
  577.         }
  578.     }
  579.  
  580.     /*
  581.      * In general, there can be several reasons that
  582.      * can have caused this fault.
  583.      *
  584.      * - non-existent mapping: the area is a scratch
  585.      *   area (e.g. stack) and so far has not been
  586.      *   allocated a frame for the faulting page
  587.      *
  588.      * - non-present mapping: another possibility,
  589.      *   currently not implemented, would be frame
  590.      *   reuse; when this becomes a possibility,
  591.      *   do not forget to distinguish between
  592.      *   the different causes
  593.      */
  594.     frame = PFN2ADDR(frame_alloc(ONE_FRAME, 0));
  595.     memsetb(PA2KA(frame), FRAME_SIZE, 0);
  596.    
  597.     /*
  598.      * Map 'page' to 'frame'.
  599.      * Note that TLB shootdown is not attempted as only new information is being
  600.      * inserted into page tables.
  601.      */
  602.     page_mapping_insert(AS, page, frame, get_area_flags(area));
  603.     page_table_unlock(AS, false);
  604.    
  605.     mutex_unlock(&area->lock);
  606.     mutex_unlock(&AS->lock);
  607.     return AS_PF_OK;
  608.  
  609. page_fault:
  610.     if (!THREAD)
  611.         return AS_PF_FAULT;
  612.    
  613.     if (THREAD->in_copy_from_uspace) {
  614.         THREAD->in_copy_from_uspace = false;
  615.         istate_set_retaddr(istate, (__address) &memcpy_from_uspace_failover_address);
  616.     } else if (THREAD->in_copy_to_uspace) {
  617.         THREAD->in_copy_to_uspace = false;
  618.         istate_set_retaddr(istate, (__address) &memcpy_to_uspace_failover_address);
  619.     } else {
  620.         return AS_PF_FAULT;
  621.     }
  622.  
  623.     return AS_PF_DEFER;
  624. }
  625.  
  626. /** Switch address spaces.
  627.  *
  628.  * Note that this function cannot sleep as it is essentially a part of
  629.  * the scheduling. Sleeping here would lead to deadlock on wakeup.
  630.  *
  631.  * @param old Old address space or NULL.
  632.  * @param new New address space.
  633.  */
  634. void as_switch(as_t *old, as_t *new)
  635. {
  636.     ipl_t ipl;
  637.     bool needs_asid = false;
  638.    
  639.     ipl = interrupts_disable();
  640.     spinlock_lock(&as_lock);
  641.  
  642.     /*
  643.      * First, take care of the old address space.
  644.      */
  645.     if (old) {
  646.         mutex_lock_active(&old->lock);
  647.         ASSERT(old->refcount);
  648.         if((--old->refcount == 0) && (old != AS_KERNEL)) {
  649.             /*
  650.              * The old address space is no longer active on
  651.              * any processor. It can be appended to the
  652.              * list of inactive address spaces with assigned
  653.              * ASID.
  654.              */
  655.              ASSERT(old->asid != ASID_INVALID);
  656.              list_append(&old->inactive_as_with_asid_link, &inactive_as_with_asid_head);
  657.         }
  658.         mutex_unlock(&old->lock);
  659.     }
  660.  
  661.     /*
  662.      * Second, prepare the new address space.
  663.      */
  664.     mutex_lock_active(&new->lock);
  665.     if ((new->refcount++ == 0) && (new != AS_KERNEL)) {
  666.         if (new->asid != ASID_INVALID)
  667.             list_remove(&new->inactive_as_with_asid_link);
  668.         else
  669.             needs_asid = true;  /* defer call to asid_get() until new->lock is released */
  670.     }
  671.     SET_PTL0_ADDRESS(new->page_table);
  672.     mutex_unlock(&new->lock);
  673.  
  674.     if (needs_asid) {
  675.         /*
  676.          * Allocation of new ASID was deferred
  677.          * until now in order to avoid deadlock.
  678.          */
  679.         asid_t asid;
  680.        
  681.         asid = asid_get();
  682.         mutex_lock_active(&new->lock);
  683.         new->asid = asid;
  684.         mutex_unlock(&new->lock);
  685.     }
  686.     spinlock_unlock(&as_lock);
  687.     interrupts_restore(ipl);
  688.    
  689.     /*
  690.      * Perform architecture-specific steps.
  691.      * (e.g. write ASID to hardware register etc.)
  692.      */
  693.     as_install_arch(new);
  694.    
  695.     AS = new;
  696. }
  697.  
  698. /** Convert address space area flags to page flags.
  699.  *
  700.  * @param aflags Flags of some address space area.
  701.  *
  702.  * @return Flags to be passed to page_mapping_insert().
  703.  */
  704. int area_flags_to_page_flags(int aflags)
  705. {
  706.     int flags;
  707.  
  708.     flags = PAGE_USER | PAGE_PRESENT;
  709.    
  710.     if (aflags & AS_AREA_READ)
  711.         flags |= PAGE_READ;
  712.        
  713.     if (aflags & AS_AREA_WRITE)
  714.         flags |= PAGE_WRITE;
  715.    
  716.     if (aflags & AS_AREA_EXEC)
  717.         flags |= PAGE_EXEC;
  718.    
  719.     if (!(aflags & AS_AREA_DEVICE))
  720.         flags |= PAGE_CACHEABLE;
  721.        
  722.     return flags;
  723. }
  724.  
  725. /** Compute flags for virtual address translation subsytem.
  726.  *
  727.  * The address space area must be locked.
  728.  * Interrupts must be disabled.
  729.  *
  730.  * @param a Address space area.
  731.  *
  732.  * @return Flags to be used in page_mapping_insert().
  733.  */
  734. int get_area_flags(as_area_t *a)
  735. {
  736.     return area_flags_to_page_flags(a->flags);
  737. }
  738.  
  739. /** Create page table.
  740.  *
  741.  * Depending on architecture, create either address space
  742.  * private or global page table.
  743.  *
  744.  * @param flags Flags saying whether the page table is for kernel address space.
  745.  *
  746.  * @return First entry of the page table.
  747.  */
  748. pte_t *page_table_create(int flags)
  749. {
  750.         ASSERT(as_operations);
  751.         ASSERT(as_operations->page_table_create);
  752.  
  753.         return as_operations->page_table_create(flags);
  754. }
  755.  
  756. /** Lock page table.
  757.  *
  758.  * This function should be called before any page_mapping_insert(),
  759.  * page_mapping_remove() and page_mapping_find().
  760.  *
  761.  * Locking order is such that address space areas must be locked
  762.  * prior to this call. Address space can be locked prior to this
  763.  * call in which case the lock argument is false.
  764.  *
  765.  * @param as Address space.
  766.  * @param lock If false, do not attempt to lock as->lock.
  767.  */
  768. void page_table_lock(as_t *as, bool lock)
  769. {
  770.     ASSERT(as_operations);
  771.     ASSERT(as_operations->page_table_lock);
  772.  
  773.     as_operations->page_table_lock(as, lock);
  774. }
  775.  
  776. /** Unlock page table.
  777.  *
  778.  * @param as Address space.
  779.  * @param unlock If false, do not attempt to unlock as->lock.
  780.  */
  781. void page_table_unlock(as_t *as, bool unlock)
  782. {
  783.     ASSERT(as_operations);
  784.     ASSERT(as_operations->page_table_unlock);
  785.  
  786.     as_operations->page_table_unlock(as, unlock);
  787. }
  788.  
  789.  
  790. /** Find address space area and lock it.
  791.  *
  792.  * The address space must be locked and interrupts must be disabled.
  793.  *
  794.  * @param as Address space.
  795.  * @param va Virtual address.
  796.  *
  797.  * @return Locked address space area containing va on success or NULL on failure.
  798.  */
  799. as_area_t *find_area_and_lock(as_t *as, __address va)
  800. {
  801.     as_area_t *a;
  802.     btree_node_t *leaf, *lnode;
  803.     int i;
  804.    
  805.     a = (as_area_t *) btree_search(&as->as_area_btree, va, &leaf);
  806.     if (a) {
  807.         /* va is the base address of an address space area */
  808.         mutex_lock(&a->lock);
  809.         return a;
  810.     }
  811.    
  812.     /*
  813.      * Search the leaf node and the righmost record of its left neighbour
  814.      * to find out whether this is a miss or va belongs to an address
  815.      * space area found there.
  816.      */
  817.    
  818.     /* First, search the leaf node itself. */
  819.     for (i = 0; i < leaf->keys; i++) {
  820.         a = (as_area_t *) leaf->value[i];
  821.         mutex_lock(&a->lock);
  822.         if ((a->base <= va) && (va < a->base + a->pages * PAGE_SIZE)) {
  823.             return a;
  824.         }
  825.         mutex_unlock(&a->lock);
  826.     }
  827.  
  828.     /*
  829.      * Second, locate the left neighbour and test its last record.
  830.      * Because of its position in the B+tree, it must have base < va.
  831.      */
  832.     if ((lnode = btree_leaf_node_left_neighbour(&as->as_area_btree, leaf))) {
  833.         a = (as_area_t *) lnode->value[lnode->keys - 1];
  834.         mutex_lock(&a->lock);
  835.         if (va < a->base + a->pages * PAGE_SIZE) {
  836.             return a;
  837.         }
  838.         mutex_unlock(&a->lock);
  839.     }
  840.  
  841.     return NULL;
  842. }
  843.  
  844. /** Check area conflicts with other areas.
  845.  *
  846.  * The address space must be locked and interrupts must be disabled.
  847.  *
  848.  * @param as Address space.
  849.  * @param va Starting virtual address of the area being tested.
  850.  * @param size Size of the area being tested.
  851.  * @param avoid_area Do not touch this area.
  852.  *
  853.  * @return True if there is no conflict, false otherwise.
  854.  */
  855. bool check_area_conflicts(as_t *as, __address va, size_t size, as_area_t *avoid_area)
  856. {
  857.     as_area_t *a;
  858.     btree_node_t *leaf, *node;
  859.     int i;
  860.    
  861.     /*
  862.      * We don't want any area to have conflicts with NULL page.
  863.      */
  864.     if (overlaps(va, size, NULL, PAGE_SIZE))
  865.         return false;
  866.    
  867.     /*
  868.      * The leaf node is found in O(log n), where n is proportional to
  869.      * the number of address space areas belonging to as.
  870.      * The check for conflicts is then attempted on the rightmost
  871.      * record in the left neighbour, the leftmost record in the right
  872.      * neighbour and all records in the leaf node itself.
  873.      */
  874.    
  875.     if ((a = (as_area_t *) btree_search(&as->as_area_btree, va, &leaf))) {
  876.         if (a != avoid_area)
  877.             return false;
  878.     }
  879.    
  880.     /* First, check the two border cases. */
  881.     if ((node = btree_leaf_node_left_neighbour(&as->as_area_btree, leaf))) {
  882.         a = (as_area_t *) node->value[node->keys - 1];
  883.         mutex_lock(&a->lock);
  884.         if (overlaps(va, size, a->base, a->pages * PAGE_SIZE)) {
  885.             mutex_unlock(&a->lock);
  886.             return false;
  887.         }
  888.         mutex_unlock(&a->lock);
  889.     }
  890.     if ((node = btree_leaf_node_right_neighbour(&as->as_area_btree, leaf))) {
  891.         a = (as_area_t *) node->value[0];
  892.         mutex_lock(&a->lock);
  893.         if (overlaps(va, size, a->base, a->pages * PAGE_SIZE)) {
  894.             mutex_unlock(&a->lock);
  895.             return false;
  896.         }
  897.         mutex_unlock(&a->lock);
  898.     }
  899.    
  900.     /* Second, check the leaf node. */
  901.     for (i = 0; i < leaf->keys; i++) {
  902.         a = (as_area_t *) leaf->value[i];
  903.    
  904.         if (a == avoid_area)
  905.             continue;
  906.    
  907.         mutex_lock(&a->lock);
  908.         if (overlaps(va, size, a->base, a->pages * PAGE_SIZE)) {
  909.             mutex_unlock(&a->lock);
  910.             return false;
  911.         }
  912.         mutex_unlock(&a->lock);
  913.     }
  914.  
  915.     /*
  916.      * So far, the area does not conflict with other areas.
  917.      * Check if it doesn't conflict with kernel address space.
  918.      */  
  919.     if (!KERNEL_ADDRESS_SPACE_SHADOWED) {
  920.         return !overlaps(va, size,
  921.             KERNEL_ADDRESS_SPACE_START, KERNEL_ADDRESS_SPACE_END-KERNEL_ADDRESS_SPACE_START);
  922.     }
  923.  
  924.     return true;
  925. }
  926.  
  927. /** Return size of the address space area with given base.  */
  928. size_t as_get_size(__address base)
  929. {
  930.     ipl_t ipl;
  931.     as_area_t *src_area;
  932.     size_t size;
  933.  
  934.     ipl = interrupts_disable();
  935.     src_area = find_area_and_lock(AS, base);
  936.     if (src_area){
  937.         size = src_area->pages * PAGE_SIZE;
  938.         mutex_unlock(&src_area->lock);
  939.     } else {
  940.         size = 0;
  941.     }
  942.     interrupts_restore(ipl);
  943.     return size;
  944. }
  945.  
  946. /*
  947.  * Address space related syscalls.
  948.  */
  949.  
  950. /** Wrapper for as_area_create(). */
  951. __native sys_as_area_create(__address address, size_t size, int flags)
  952. {
  953.     if (as_area_create(AS, flags, size, address, AS_AREA_ATTR_NONE))
  954.         return (__native) address;
  955.     else
  956.         return (__native) -1;
  957. }
  958.  
  959. /** Wrapper for as_area_resize. */
  960. __native sys_as_area_resize(__address address, size_t size, int flags)
  961. {
  962.     return (__native) as_area_resize(AS, address, size, 0);
  963. }
  964.  
  965. /** Wrapper for as_area_destroy. */
  966. __native sys_as_area_destroy(__address address)
  967. {
  968.     return (__native) as_area_destroy(AS, address);
  969. }
  970.