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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 <panic.h>
  52. #include <arch/asm.h>
  53. #include <debug.h>
  54. #include <memstr.h>
  55. #include <macros.h>
  56. #include <arch.h>
  57. #include <print.h>
  58.  
  59. as_operations_t *as_operations = NULL;
  60.  
  61. /** Address space lock. It protects inactive_as_with_asid_head. */
  62. SPINLOCK_INITIALIZE(as_lock);
  63.  
  64. /**
  65.  * This list contains address spaces that are not active on any
  66.  * processor and that have valid ASID.
  67.  */
  68. LIST_INITIALIZE(inactive_as_with_asid_head);
  69.  
  70. /** Kernel address space. */
  71. as_t *AS_KERNEL = NULL;
  72.  
  73. static int get_area_flags(as_area_t *a);
  74. static as_area_t *find_area_and_lock(as_t *as, __address va);
  75. static bool check_area_conflicts(as_t *as, __address va, size_t size, as_area_t *avoid_area);
  76.  
  77. /** Initialize address space subsystem. */
  78. void as_init(void)
  79. {
  80.     as_arch_init();
  81.     AS_KERNEL = as_create(FLAG_AS_KERNEL);
  82.         if (!AS_KERNEL)
  83.                 panic("can't create kernel address space\n");
  84. }
  85.  
  86. /** Create address space.
  87.  *
  88.  * @param flags Flags that influence way in wich the address space is created.
  89.  */
  90. as_t *as_create(int flags)
  91. {
  92.     as_t *as;
  93.  
  94.     as = (as_t *) malloc(sizeof(as_t), 0);
  95.     link_initialize(&as->inactive_as_with_asid_link);
  96.     spinlock_initialize(&as->lock, "as_lock");
  97.     list_initialize(&as->as_area_head);
  98.    
  99.     if (flags & FLAG_AS_KERNEL)
  100.         as->asid = ASID_KERNEL;
  101.     else
  102.         as->asid = ASID_INVALID;
  103.    
  104.     as->refcount = 0;
  105.     as->page_table = page_table_create(flags);
  106.  
  107.     return as;
  108. }
  109.  
  110. /** Free Adress space */
  111. void as_free(as_t *as)
  112. {
  113.     ASSERT(as->refcount == 0);
  114.  
  115.     /* TODO: free as_areas and other resources held by as */
  116.     /* TODO: free page table */
  117.     free(as);
  118. }
  119.  
  120. /** Create address space area of common attributes.
  121.  *
  122.  * The created address space area is added to the target address space.
  123.  *
  124.  * @param as Target address space.
  125.  * @param flags Flags of the area.
  126.  * @param size Size of area.
  127.  * @param base Base address of area.
  128.  *
  129.  * @return Address space area on success or NULL on failure.
  130.  */
  131. as_area_t *as_area_create(as_t *as, int flags, size_t size, __address base)
  132. {
  133.     ipl_t ipl;
  134.     as_area_t *a;
  135.    
  136.     if (base % PAGE_SIZE)
  137.         return NULL;
  138.  
  139.     /* Writeable executable areas are not supported. */
  140.     if ((flags & AS_AREA_EXEC) && (flags & AS_AREA_WRITE))
  141.         return NULL;
  142.    
  143.     ipl = interrupts_disable();
  144.     spinlock_lock(&as->lock);
  145.    
  146.     if (!check_area_conflicts(as, base, size, NULL)) {
  147.         spinlock_unlock(&as->lock);
  148.         interrupts_restore(ipl);
  149.         return NULL;
  150.     }
  151.    
  152.     a = (as_area_t *) malloc(sizeof(as_area_t), 0);
  153.  
  154.     spinlock_initialize(&a->lock, "as_area_lock");
  155.    
  156.     link_initialize(&a->link);         
  157.     a->flags = flags;
  158.     a->pages = SIZE2FRAMES(size);
  159.     a->base = base;
  160.    
  161.     list_append(&a->link, &as->as_area_head);
  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 (!check_area_conflicts(as, address, pages * PAGE_SIZE, area)) {
  449.         spinlock_unlock(&area->lock);
  450.         spinlock_unlock(&as->lock);    
  451.         interrupts_restore(ipl);
  452.         return (__address) -1;
  453.     }
  454.  
  455.     if (pages < area->pages) {
  456.         int i;
  457.  
  458.         /*
  459.          * Shrinking the area.
  460.          */
  461.         for (i = pages; i < area->pages; i++) {
  462.             pte_t *pte;
  463.            
  464.             /*
  465.              * Releasing physical memory.
  466.              * This depends on the fact that the memory was allocated using frame_alloc().
  467.              */
  468.             page_table_lock(as, false);
  469.             pte = page_mapping_find(as, area->base + i*PAGE_SIZE);
  470.             if (pte && PTE_VALID(pte)) {
  471.                 __address frame;
  472.  
  473.                 ASSERT(PTE_PRESENT(pte));
  474.                 frame = PTE_GET_FRAME(pte);
  475.                 page_mapping_remove(as, area->base + i*PAGE_SIZE);
  476.                 page_table_unlock(as, false);
  477.  
  478.                 frame_free(ADDR2PFN(frame));
  479.             } else {
  480.                 page_table_unlock(as, false);
  481.             }
  482.         }
  483.         /*
  484.          * Invalidate TLB's.
  485.          */
  486.         tlb_shootdown_start(TLB_INVL_PAGES, AS->asid, area->base + pages*PAGE_SIZE, area->pages - pages);
  487.         tlb_invalidate_pages(AS->asid, area->base + pages*PAGE_SIZE, area->pages - pages);
  488.         tlb_shootdown_finalize();
  489.     }
  490.  
  491.     area->pages = pages;
  492.    
  493.     spinlock_unlock(&area->lock);
  494.     spinlock_unlock(&as->lock);
  495.     interrupts_restore(ipl);
  496.  
  497.     return address;
  498. }
  499.  
  500. /** Find address space area and lock it.
  501.  *
  502.  * The address space must be locked and interrupts must be disabled.
  503.  *
  504.  * @param as Address space.
  505.  * @param va Virtual address.
  506.  *
  507.  * @return Locked address space area containing va on success or NULL on failure.
  508.  */
  509. as_area_t *find_area_and_lock(as_t *as, __address va)
  510. {
  511.     link_t *cur;
  512.     as_area_t *a;
  513.    
  514.     for (cur = as->as_area_head.next; cur != &as->as_area_head; cur = cur->next) {
  515.         a = list_get_instance(cur, as_area_t, link);
  516.         spinlock_lock(&a->lock);
  517.  
  518.         if ((va >= a->base) && (va < a->base + a->pages * PAGE_SIZE))
  519.             return a;
  520.        
  521.         spinlock_unlock(&a->lock);
  522.     }
  523.  
  524.     return NULL;
  525. }
  526.  
  527. /** Check area conflicts with other areas.
  528.  *
  529.  * The address space must be locked and interrupts must be disabled.
  530.  *
  531.  * @param as Address space.
  532.  * @param va Starting virtual address of the area being tested.
  533.  * @param size Size of the area being tested.
  534.  * @param avoid_area Do not touch this area.
  535.  *
  536.  * @return True if there is no conflict, false otherwise.
  537.  */
  538. bool check_area_conflicts(as_t *as, __address va, size_t size, as_area_t *avoid_area)
  539. {
  540.     link_t *cur;
  541.     as_area_t *a;
  542.    
  543.     /*
  544.      * We don't want any area to have conflicts with NULL page.
  545.      */
  546.     if (overlaps(va, size, NULL, PAGE_SIZE))
  547.         return false;
  548.    
  549.     for (cur = as->as_area_head.next; cur != &as->as_area_head; cur = cur->next) {
  550.         __address a_start;
  551.         size_t a_size;
  552.    
  553.         a = list_get_instance(cur, as_area_t, link);
  554.         if (a == avoid_area)
  555.             continue;
  556.            
  557.         spinlock_lock(&a->lock);
  558.  
  559.         a_start = a->base;
  560.         a_size = a->pages * PAGE_SIZE;
  561.  
  562.         spinlock_unlock(&a->lock);
  563.  
  564.         if (overlaps(va, size, a_start, a_size))
  565.             return false;      
  566.  
  567.     }
  568.  
  569.     /*
  570.      * So far, the area does not conflict with other areas.
  571.      * Check if it doesn't conflict with kernel address space.
  572.      */  
  573.     if (!KERNEL_ADDRESS_SPACE_SHADOWED) {
  574.         return !overlaps(va, size,
  575.             KERNEL_ADDRESS_SPACE_START, KERNEL_ADDRESS_SPACE_END-KERNEL_ADDRESS_SPACE_START);
  576.     }
  577.  
  578.     return true;
  579. }
  580.