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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.  * This file contains address space manipulation functions.
  31.  * Roughly speaking, this is a higher-level client of
  32.  * Virtual Address Translation (VAT) subsystem.
  33.  */
  34.  
  35. #include <mm/as.h>
  36. #include <arch/mm/as.h>
  37. #include <mm/page.h>
  38. #include <mm/frame.h>
  39. #include <mm/slab.h>
  40. #include <mm/tlb.h>
  41. #include <arch/mm/page.h>
  42. #include <genarch/mm/page_pt.h>
  43. #include <genarch/mm/page_ht.h>
  44. #include <mm/asid.h>
  45. #include <arch/mm/asid.h>
  46. #include <arch/types.h>
  47. #include <typedefs.h>
  48. #include <synch/spinlock.h>
  49. #include <config.h>
  50. #include <adt/list.h>
  51. #include <adt/btree.h>
  52. #include <panic.h>
  53. #include <arch/asm.h>
  54. #include <debug.h>
  55. #include <memstr.h>
  56. #include <macros.h>
  57. #include <arch.h>
  58. #include <print.h>
  59.  
  60. as_operations_t *as_operations = NULL;
  61.  
  62. /** Address space lock. It protects inactive_as_with_asid_head. */
  63. SPINLOCK_INITIALIZE(as_lock);
  64.  
  65. /**
  66.  * This list contains address spaces that are not active on any
  67.  * processor and that have valid ASID.
  68.  */
  69. LIST_INITIALIZE(inactive_as_with_asid_head);
  70.  
  71. /** Kernel address space. */
  72. as_t *AS_KERNEL = NULL;
  73.  
  74. static int get_area_flags(as_area_t *a);
  75. static as_area_t *find_area_and_lock(as_t *as, __address va);
  76. static bool check_area_conflicts(as_t *as, __address va, size_t size, as_area_t *avoid_area);
  77.  
  78. /** Initialize address space subsystem. */
  79. void as_init(void)
  80. {
  81.     as_arch_init();
  82.     AS_KERNEL = as_create(FLAG_AS_KERNEL);
  83.         if (!AS_KERNEL)
  84.                 panic("can't create kernel address space\n");
  85. }
  86.  
  87. /** Create address space.
  88.  *
  89.  * @param flags Flags that influence way in wich the address space is created.
  90.  */
  91. as_t *as_create(int flags)
  92. {
  93.     as_t *as;
  94.  
  95.     as = (as_t *) malloc(sizeof(as_t), 0);
  96.     link_initialize(&as->inactive_as_with_asid_link);
  97.     spinlock_initialize(&as->lock, "as_lock");
  98.     btree_create(&as->as_area_btree);
  99.    
  100.     if (flags & FLAG_AS_KERNEL)
  101.         as->asid = ASID_KERNEL;
  102.     else
  103.         as->asid = ASID_INVALID;
  104.    
  105.     as->refcount = 0;
  106.     as->page_table = page_table_create(flags);
  107.  
  108.     return as;
  109. }
  110.  
  111. /** Free Adress space */
  112. void as_free(as_t *as)
  113. {
  114.     ASSERT(as->refcount == 0);
  115.  
  116.     /* TODO: free as_areas and other resources held by as */
  117.     /* TODO: free page table */
  118.     free(as);
  119. }
  120.  
  121. /** Create address space area of common attributes.
  122.  *
  123.  * The created address space area is added to the target address space.
  124.  *
  125.  * @param as Target address space.
  126.  * @param flags Flags of the area.
  127.  * @param size Size of area.
  128.  * @param base Base address of area.
  129.  *
  130.  * @return Address space area on success or NULL on failure.
  131.  */
  132. as_area_t *as_area_create(as_t *as, int flags, size_t size, __address base)
  133. {
  134.     ipl_t ipl;
  135.     as_area_t *a;
  136.    
  137.     if (base % PAGE_SIZE)
  138.         return NULL;
  139.  
  140.     /* Writeable executable areas are not supported. */
  141.     if ((flags & AS_AREA_EXEC) && (flags & AS_AREA_WRITE))
  142.         return NULL;
  143.    
  144.     ipl = interrupts_disable();
  145.     spinlock_lock(&as->lock);
  146.    
  147.     if (!check_area_conflicts(as, base, size, NULL)) {
  148.         spinlock_unlock(&as->lock);
  149.         interrupts_restore(ipl);
  150.         return NULL;
  151.     }
  152.    
  153.     a = (as_area_t *) malloc(sizeof(as_area_t), 0);
  154.  
  155.     spinlock_initialize(&a->lock, "as_area_lock");
  156.    
  157.     a->flags = flags;
  158.     a->pages = SIZE2FRAMES(size);
  159.     a->base = base;
  160.    
  161.     btree_insert(&as->as_area_btree, base, (void *) a, NULL);
  162.  
  163.     spinlock_unlock(&as->lock);
  164.     interrupts_restore(ipl);
  165.  
  166.     return a;
  167. }
  168.  
  169. /** Initialize mapping for one page of address space.
  170.  *
  171.  * This functions maps 'page' to 'frame' according
  172.  * to attributes of the address space area to
  173.  * wich 'page' belongs.
  174.  *
  175.  * @param as Target address space.
  176.  * @param page Virtual page within the area.
  177.  * @param frame Physical frame to which page will be mapped.
  178.  */
  179. void as_set_mapping(as_t *as, __address page, __address frame)
  180. {
  181.     as_area_t *area;
  182.     ipl_t ipl;
  183.    
  184.     ipl = interrupts_disable();
  185.     page_table_lock(as, true);
  186.    
  187.     area = find_area_and_lock(as, page);
  188.     if (!area) {
  189.         panic("page not part of any as_area\n");
  190.     }
  191.  
  192.     page_mapping_insert(as, page, frame, get_area_flags(area));
  193.    
  194.     spinlock_unlock(&area->lock);
  195.     page_table_unlock(as, true);
  196.     interrupts_restore(ipl);
  197. }
  198.  
  199. /** Handle page fault within the current address space.
  200.  *
  201.  * This is the high-level page fault handler.
  202.  * Interrupts are assumed disabled.
  203.  *
  204.  * @param page Faulting page.
  205.  *
  206.  * @return 0 on page fault, 1 on success.
  207.  */
  208. int as_page_fault(__address page)
  209. {
  210.     pte_t *pte;
  211.     as_area_t *area;
  212.     __address frame;
  213.    
  214.     ASSERT(AS);
  215.  
  216.     spinlock_lock(&AS->lock);
  217.     area = find_area_and_lock(AS, page);   
  218.     if (!area) {
  219.         /*
  220.          * No area contained mapping for 'page'.
  221.          * Signal page fault to low-level handler.
  222.          */
  223.         spinlock_unlock(&AS->lock);
  224.         return 0;
  225.     }
  226.  
  227.     page_table_lock(AS, false);
  228.    
  229.     /*
  230.      * To avoid race condition between two page faults
  231.      * on the same address, we need to make sure
  232.      * the mapping has not been already inserted.
  233.      */
  234.     if ((pte = page_mapping_find(AS, page))) {
  235.         if (PTE_PRESENT(pte)) {
  236.             page_table_unlock(AS, false);
  237.             spinlock_unlock(&area->lock);
  238.             spinlock_unlock(&AS->lock);
  239.             return 1;
  240.         }
  241.     }
  242.  
  243.     /*
  244.      * In general, there can be several reasons that
  245.      * can have caused this fault.
  246.      *
  247.      * - non-existent mapping: the area is a scratch
  248.      *   area (e.g. stack) and so far has not been
  249.      *   allocated a frame for the faulting page
  250.      *
  251.      * - non-present mapping: another possibility,
  252.      *   currently not implemented, would be frame
  253.      *   reuse; when this becomes a possibility,
  254.      *   do not forget to distinguish between
  255.      *   the different causes
  256.      */
  257.     frame = PFN2ADDR(frame_alloc(ONE_FRAME, 0));
  258.     memsetb(PA2KA(frame), FRAME_SIZE, 0);
  259.    
  260.     /*
  261.      * Map 'page' to 'frame'.
  262.      * Note that TLB shootdown is not attempted as only new information is being
  263.      * inserted into page tables.
  264.      */
  265.     page_mapping_insert(AS, page, frame, get_area_flags(area));
  266.     page_table_unlock(AS, false);
  267.    
  268.     spinlock_unlock(&area->lock);
  269.     spinlock_unlock(&AS->lock);
  270.     return 1;
  271. }
  272.  
  273. /** Switch address spaces.
  274.  *
  275.  * @param old Old address space or NULL.
  276.  * @param new New address space.
  277.  */
  278. void as_switch(as_t *old, as_t *new)
  279. {
  280.     ipl_t ipl;
  281.     bool needs_asid = false;
  282.    
  283.     ipl = interrupts_disable();
  284.     spinlock_lock(&as_lock);
  285.  
  286.     /*
  287.      * First, take care of the old address space.
  288.      */
  289.     if (old) {
  290.         spinlock_lock(&old->lock);
  291.         ASSERT(old->refcount);
  292.         if((--old->refcount == 0) && (old != AS_KERNEL)) {
  293.             /*
  294.              * The old address space is no longer active on
  295.              * any processor. It can be appended to the
  296.              * list of inactive address spaces with assigned
  297.              * ASID.
  298.              */
  299.              ASSERT(old->asid != ASID_INVALID);
  300.              list_append(&old->inactive_as_with_asid_link, &inactive_as_with_asid_head);
  301.         }
  302.         spinlock_unlock(&old->lock);
  303.     }
  304.  
  305.     /*
  306.      * Second, prepare the new address space.
  307.      */
  308.     spinlock_lock(&new->lock);
  309.     if ((new->refcount++ == 0) && (new != AS_KERNEL)) {
  310.         if (new->asid != ASID_INVALID)
  311.             list_remove(&new->inactive_as_with_asid_link);
  312.         else
  313.             needs_asid = true;  /* defer call to asid_get() until new->lock is released */
  314.     }
  315.     SET_PTL0_ADDRESS(new->page_table);
  316.     spinlock_unlock(&new->lock);
  317.  
  318.     if (needs_asid) {
  319.         /*
  320.          * Allocation of new ASID was deferred
  321.          * until now in order to avoid deadlock.
  322.          */
  323.         asid_t asid;
  324.        
  325.         asid = asid_get();
  326.         spinlock_lock(&new->lock);
  327.         new->asid = asid;
  328.         spinlock_unlock(&new->lock);
  329.     }
  330.     spinlock_unlock(&as_lock);
  331.     interrupts_restore(ipl);
  332.    
  333.     /*
  334.      * Perform architecture-specific steps.
  335.      * (e.g. write ASID to hardware register etc.)
  336.      */
  337.     as_install_arch(new);
  338.    
  339.     AS = new;
  340. }
  341.  
  342. /** Compute flags for virtual address translation subsytem.
  343.  *
  344.  * The address space area must be locked.
  345.  * Interrupts must be disabled.
  346.  *
  347.  * @param a Address space area.
  348.  *
  349.  * @return Flags to be used in page_mapping_insert().
  350.  */
  351. int get_area_flags(as_area_t *a)
  352. {
  353.     int flags;
  354.  
  355.     flags = PAGE_USER | PAGE_PRESENT | PAGE_CACHEABLE;
  356.    
  357.     if (a->flags & AS_AREA_READ)
  358.         flags |= PAGE_READ;
  359.        
  360.     if (a->flags & AS_AREA_WRITE)
  361.         flags |= PAGE_WRITE;
  362.    
  363.     if (a->flags & AS_AREA_EXEC)
  364.         flags |= PAGE_EXEC;
  365.    
  366.     return flags;
  367. }
  368.  
  369. /** Create page table.
  370.  *
  371.  * Depending on architecture, create either address space
  372.  * private or global page table.
  373.  *
  374.  * @param flags Flags saying whether the page table is for kernel address space.
  375.  *
  376.  * @return First entry of the page table.
  377.  */
  378. pte_t *page_table_create(int flags)
  379. {
  380.         ASSERT(as_operations);
  381.         ASSERT(as_operations->page_table_create);
  382.  
  383.         return as_operations->page_table_create(flags);
  384. }
  385.  
  386. /** Lock page table.
  387.  *
  388.  * This function should be called before any page_mapping_insert(),
  389.  * page_mapping_remove() and page_mapping_find().
  390.  *
  391.  * Locking order is such that address space areas must be locked
  392.  * prior to this call. Address space can be locked prior to this
  393.  * call in which case the lock argument is false.
  394.  *
  395.  * @param as Address space.
  396.  * @param as_locked If false, do not attempt to lock as->lock.
  397.  */
  398. void page_table_lock(as_t *as, bool lock)
  399. {
  400.     ASSERT(as_operations);
  401.     ASSERT(as_operations->page_table_lock);
  402.  
  403.     as_operations->page_table_lock(as, lock);
  404. }
  405.  
  406. /** Unlock page table.
  407.  *
  408.  * @param as Address space.
  409.  * @param as_locked If false, do not attempt to unlock as->lock.
  410.  */
  411. void page_table_unlock(as_t *as, bool unlock)
  412. {
  413.     ASSERT(as_operations);
  414.     ASSERT(as_operations->page_table_unlock);
  415.  
  416.     as_operations->page_table_unlock(as, unlock);
  417. }
  418.  
  419. /** Find address space area and change it.
  420.  *
  421.  * @param as Address space.
  422.  * @param address Virtual address belonging to the area to be changed. Must be page-aligned.
  423.  * @param size New size of the virtual memory block starting at address.
  424.  * @param flags Flags influencing the remap operation. Currently unused.
  425.  *
  426.  * @return address on success, (__address) -1 otherwise.
  427.  */
  428. __address as_remap(as_t *as, __address address, size_t size, int flags)
  429. {
  430.     as_area_t *area = NULL;
  431.     ipl_t ipl;
  432.     size_t pages;
  433.    
  434.     ipl = interrupts_disable();
  435.     spinlock_lock(&as->lock);
  436.    
  437.     /*
  438.      * Locate the area.
  439.      */
  440.     area = find_area_and_lock(as, address);
  441.     if (!area) {
  442.         spinlock_unlock(&as->lock);
  443.         interrupts_restore(ipl);
  444.         return (__address) -1;
  445.     }
  446.  
  447.     pages = SIZE2FRAMES((address - area->base) + size);
  448.     if (pages < area->pages) {
  449.         int i;
  450.  
  451.         /*
  452.          * Shrinking the area.
  453.          * No need to check for overlaps.
  454.          */
  455.         for (i = pages; i < area->pages; i++) {
  456.             pte_t *pte;
  457.            
  458.             /*
  459.              * Releasing physical memory.
  460.              * This depends on the fact that the memory was allocated using frame_alloc().
  461.              */
  462.             page_table_lock(as, false);
  463.             pte = page_mapping_find(as, area->base + i*PAGE_SIZE);
  464.             if (pte && PTE_VALID(pte)) {
  465.                 __address frame;
  466.  
  467.                 ASSERT(PTE_PRESENT(pte));
  468.                 frame = PTE_GET_FRAME(pte);
  469.                 page_mapping_remove(as, area->base + i*PAGE_SIZE);
  470.                 page_table_unlock(as, false);
  471.  
  472.                 frame_free(ADDR2PFN(frame));
  473.             } else {
  474.                 page_table_unlock(as, false);
  475.             }
  476.         }
  477.         /*
  478.          * Invalidate TLB's.
  479.          */
  480.         tlb_shootdown_start(TLB_INVL_PAGES, AS->asid, area->base + pages*PAGE_SIZE, area->pages - pages);
  481.         tlb_invalidate_pages(AS->asid, area->base + pages*PAGE_SIZE, area->pages - pages);
  482.         tlb_shootdown_finalize();
  483.     } else {
  484.         /*
  485.          * Growing the area.
  486.          * Check for overlaps with other address space areas.
  487.          */
  488.         if (!check_area_conflicts(as, address, pages * PAGE_SIZE, area)) {
  489.             spinlock_unlock(&area->lock);
  490.             spinlock_unlock(&as->lock);    
  491.             interrupts_restore(ipl);
  492.             return (__address) -1;
  493.         }
  494.     }
  495.  
  496.     area->pages = pages;
  497.    
  498.     spinlock_unlock(&area->lock);
  499.     spinlock_unlock(&as->lock);
  500.     interrupts_restore(ipl);
  501.  
  502.     return address;
  503. }
  504.  
  505. /** Find address space area and lock it.
  506.  *
  507.  * The address space must be locked and interrupts must be disabled.
  508.  *
  509.  * @param as Address space.
  510.  * @param va Virtual address.
  511.  *
  512.  * @return Locked address space area containing va on success or NULL on failure.
  513.  */
  514. as_area_t *find_area_and_lock(as_t *as, __address va)
  515. {
  516.     as_area_t *a;
  517.     btree_node_t *leaf, *lnode;
  518.     int i;
  519.    
  520.     a = (as_area_t *) btree_search(&as->as_area_btree, va, &leaf);
  521.     if (a) {
  522.         /* va is the base address of an address space area */
  523.         spinlock_lock(&a->lock);
  524.         return a;
  525.     }
  526.    
  527.     /*
  528.      * Search the leaf node and the righmost record of its left neighbour
  529.      * to find out whether this is a miss or va belongs to an address
  530.      * space area found there.
  531.      */
  532.    
  533.     /* First, search the leaf node itself. */
  534.     for (i = 0; i < leaf->keys; i++) {
  535.         a = (as_area_t *) leaf->value[i];
  536.         spinlock_lock(&a->lock);
  537.         if ((a->base <= va) && (va < a->base + a->pages * PAGE_SIZE)) {
  538.             return a;
  539.         }
  540.         spinlock_unlock(&a->lock);
  541.     }
  542.  
  543.     /*
  544.      * Second, locate the left neighbour and test its last record.
  545.      * Because of its position in the B+tree, it must have base < va.
  546.      */
  547.     if ((lnode = btree_leaf_node_left_neighbour(&as->as_area_btree, leaf))) {
  548.         a = (as_area_t *) lnode->value[lnode->keys - 1];
  549.         spinlock_lock(&a->lock);
  550.         if (va < a->base + a->pages * PAGE_SIZE) {
  551.             return a;
  552.         }
  553.         spinlock_unlock(&a->lock);
  554.     }
  555.  
  556.     return NULL;
  557. }
  558.  
  559. /** Check area conflicts with other areas.
  560.  *
  561.  * The address space must be locked and interrupts must be disabled.
  562.  *
  563.  * @param as Address space.
  564.  * @param va Starting virtual address of the area being tested.
  565.  * @param size Size of the area being tested.
  566.  * @param avoid_area Do not touch this area.
  567.  *
  568.  * @return True if there is no conflict, false otherwise.
  569.  */
  570. bool check_area_conflicts(as_t *as, __address va, size_t size, as_area_t *avoid_area)
  571. {
  572.     as_area_t *a;
  573.     btree_node_t *leaf, *node;
  574.     int i;
  575.    
  576.     /*
  577.      * We don't want any area to have conflicts with NULL page.
  578.      */
  579.     if (overlaps(va, size, NULL, PAGE_SIZE))
  580.         return false;
  581.    
  582.     /*
  583.      * The leaf node is found in O(log n), where n is proportional to
  584.      * the number of address space areas belonging to as.
  585.      * The check for conflicts is then attempted on the rightmost
  586.      * record in the left neighbour, the leftmost record in the right
  587.      * neighbour and all records in the leaf node itself.
  588.      */
  589.    
  590.     if ((a = (as_area_t *) btree_search(&as->as_area_btree, va, &leaf))) {
  591.         if (a != avoid_area)
  592.             return false;
  593.     }
  594.    
  595.     /* First, check the two border cases. */
  596.     if ((node = btree_leaf_node_left_neighbour(&as->as_area_btree, leaf))) {
  597.         a = (as_area_t *) node->value[node->keys - 1];
  598.         spinlock_lock(&a->lock);
  599.         if (overlaps(va, size, a->base, a->pages * PAGE_SIZE)) {
  600.             spinlock_unlock(&a->lock);
  601.             return false;
  602.         }
  603.         spinlock_unlock(&a->lock);
  604.     }
  605.     if ((node = btree_leaf_node_right_neighbour(&as->as_area_btree, leaf))) {
  606.         a = (as_area_t *) node->value[0];
  607.         spinlock_lock(&a->lock);
  608.         if (overlaps(va, size, a->base, a->pages * PAGE_SIZE)) {
  609.             spinlock_unlock(&a->lock);
  610.             return false;
  611.         }
  612.         spinlock_unlock(&a->lock);
  613.     }
  614.    
  615.     /* Second, check the leaf node. */
  616.     for (i = 0; i < leaf->keys; i++) {
  617.         a = (as_area_t *) leaf->value[i];
  618.    
  619.         if (a == avoid_area)
  620.             continue;
  621.    
  622.         spinlock_lock(&a->lock);
  623.         if (overlaps(va, size, a->base, a->pages * PAGE_SIZE)) {
  624.             spinlock_unlock(&a->lock);
  625.             return false;
  626.         }
  627.         spinlock_unlock(&a->lock);
  628.     }
  629.  
  630.     /*
  631.      * So far, the area does not conflict with other areas.
  632.      * Check if it doesn't conflict with kernel address space.
  633.      */  
  634.     if (!KERNEL_ADDRESS_SPACE_SHADOWED) {
  635.         return !overlaps(va, size,
  636.             KERNEL_ADDRESS_SPACE_START, KERNEL_ADDRESS_SPACE_END-KERNEL_ADDRESS_SPACE_START);
  637.     }
  638.  
  639.     return true;
  640. }
  641.