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