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  1. /*
  2.  * Copyright (c) 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. /** @addtogroup genericmm
  30.  * @{
  31.  */
  32.  
  33. /**
  34.  * @file
  35.  * @brief   Backend for address space areas backed by an ELF image.
  36.  */
  37.  
  38. #include <lib/elf.h>
  39. #include <debug.h>
  40. #include <arch/types.h>
  41. #include <mm/as.h>
  42. #include <mm/frame.h>
  43. #include <mm/slab.h>
  44. #include <mm/page.h>
  45. #include <genarch/mm/page_pt.h>
  46. #include <genarch/mm/page_ht.h>
  47. #include <align.h>
  48. #include <memstr.h>
  49. #include <macros.h>
  50. #include <arch.h>
  51.  
  52. #ifdef CONFIG_VIRT_IDX_DCACHE
  53. #include <arch/mm/cache.h>
  54. #endif
  55.  
  56. static int elf_page_fault(as_area_t *area, uintptr_t addr, pf_access_t access);
  57. static void elf_frame_free(as_area_t *area, uintptr_t page, uintptr_t frame);
  58. static void elf_share(as_area_t *area);
  59.  
  60. mem_backend_t elf_backend = {
  61.     .page_fault = elf_page_fault,
  62.     .frame_free = elf_frame_free,
  63.     .share = elf_share
  64. };
  65.  
  66. /** Service a page fault in the ELF backend address space area.
  67.  *
  68.  * The address space area and page tables must be already locked.
  69.  *
  70.  * @param area Pointer to the address space area.
  71.  * @param addr Faulting virtual address.
  72.  * @param access Access mode that caused the fault (i.e. read/write/exec).
  73.  *
  74.  * @return AS_PF_FAULT on failure (i.e. page fault) or AS_PF_OK on success (i.e.
  75.  *     serviced).
  76.  */
  77. int elf_page_fault(as_area_t *area, uintptr_t addr, pf_access_t access)
  78. {
  79.     elf_header_t *elf = area->backend_data.elf;
  80.     elf_segment_header_t *entry = area->backend_data.segment;
  81.     btree_node_t *leaf;
  82.     uintptr_t base, frame;
  83.     index_t i;
  84.     bool dirty = false;
  85.  
  86.     if (!as_area_check_access(area, access))
  87.         return AS_PF_FAULT;
  88.  
  89.     ASSERT((addr >= entry->p_vaddr) &&
  90.         (addr < entry->p_vaddr + entry->p_memsz));
  91.     i = (addr - entry->p_vaddr) >> PAGE_WIDTH;
  92.     base = (uintptr_t) (((void *) elf) + entry->p_offset);
  93.     ASSERT(ALIGN_UP(base, FRAME_SIZE) == base);
  94.  
  95.     if (area->sh_info) {
  96.         bool found = false;
  97.  
  98.         /*
  99.          * The address space area is shared.
  100.          */
  101.          
  102.         mutex_lock(&area->sh_info->lock);
  103.         frame = (uintptr_t) btree_search(&area->sh_info->pagemap,
  104.             ALIGN_DOWN(addr, PAGE_SIZE) - area->base, &leaf);
  105.         if (!frame) {
  106.             int i;
  107.  
  108.             /*
  109.              * Workaround for valid NULL address.
  110.              */
  111.  
  112.             for (i = 0; i < leaf->keys; i++) {
  113.                 if (leaf->key[i] ==
  114.                     ALIGN_DOWN(addr, PAGE_SIZE)) {
  115.                     found = true;
  116.                     break;
  117.                 }
  118.             }
  119.         }
  120.         if (frame || found) {
  121.             frame_reference_add(ADDR2PFN(frame));
  122.             page_mapping_insert(AS, addr, frame,
  123.                 as_area_get_flags(area));
  124.             if (!used_space_insert(area,
  125.                 ALIGN_DOWN(addr, PAGE_SIZE), 1))
  126.                 panic("Could not insert used space.\n");
  127.             mutex_unlock(&area->sh_info->lock);
  128.             return AS_PF_OK;
  129.         }
  130.     }
  131.    
  132.     /*
  133.      * The area is either not shared or the pagemap does not contain the
  134.      * mapping.
  135.      */
  136.    
  137.     if (ALIGN_DOWN(addr, PAGE_SIZE) + PAGE_SIZE <
  138.         entry->p_vaddr + entry->p_filesz) {
  139.         /*
  140.          * Initialized portion of the segment. The memory is backed
  141.          * directly by the content of the ELF image. Pages are
  142.          * only copied if the segment is writable so that there
  143.          * can be more instantions of the same memory ELF image
  144.          * used at a time. Note that this could be later done
  145.          * as COW.
  146.          */
  147.         if (entry->p_flags & PF_W) {
  148.             frame = (uintptr_t)frame_alloc(ONE_FRAME, 0);
  149.             memcpy((void *) PA2KA(frame),
  150.                 (void *) (base + i * FRAME_SIZE), FRAME_SIZE);
  151.             dirty = true;
  152.  
  153.             if (area->sh_info) {
  154.                 frame_reference_add(ADDR2PFN(frame));
  155.                 btree_insert(&area->sh_info->pagemap,
  156.                     ALIGN_DOWN(addr, PAGE_SIZE) - area->base,
  157.                     (void *) frame, leaf);
  158.             }
  159.  
  160.         } else {
  161.             frame = KA2PA(base + i*FRAME_SIZE);
  162.         }  
  163.     } else if (ALIGN_DOWN(addr, PAGE_SIZE) >=
  164.         ALIGN_UP(entry->p_vaddr + entry->p_filesz, PAGE_SIZE)) {
  165.         /*
  166.          * This is the uninitialized portion of the segment.
  167.          * It is not physically present in the ELF image.
  168.          * To resolve the situation, a frame must be allocated
  169.          * and cleared.
  170.          */
  171.         frame = (uintptr_t)frame_alloc(ONE_FRAME, 0);
  172.         memsetb(PA2KA(frame), FRAME_SIZE, 0);
  173.         dirty = true;
  174.  
  175.         if (area->sh_info) {
  176.             frame_reference_add(ADDR2PFN(frame));
  177.             btree_insert(&area->sh_info->pagemap,
  178.                 ALIGN_DOWN(addr, PAGE_SIZE) - area->base,
  179.                 (void *) frame, leaf);
  180.         }
  181.  
  182.     } else {
  183.         size_t size;
  184.         /*
  185.          * The mixed case.
  186.          * The lower part is backed by the ELF image and
  187.          * the upper part is anonymous memory.
  188.          */
  189.         size = entry->p_filesz - (i<<PAGE_WIDTH);
  190.         frame = (uintptr_t)frame_alloc(ONE_FRAME, 0);
  191.         memsetb(PA2KA(frame) + size, FRAME_SIZE - size, 0);
  192.         memcpy((void *) PA2KA(frame), (void *) (base + i * FRAME_SIZE),
  193.             size);
  194.         dirty = true;
  195.  
  196.         if (area->sh_info) {
  197.             frame_reference_add(ADDR2PFN(frame));
  198.             btree_insert(&area->sh_info->pagemap,
  199.                 ALIGN_DOWN(addr, PAGE_SIZE) - area->base,
  200.                 (void *) frame, leaf);
  201.         }
  202.  
  203.     }
  204.    
  205.     if (area->sh_info)
  206.         mutex_unlock(&area->sh_info->lock);
  207.    
  208.     page_mapping_insert(AS, addr, frame, as_area_get_flags(area));
  209.     if (!used_space_insert(area, ALIGN_DOWN(addr, PAGE_SIZE), 1))
  210.         panic("Could not insert used space.\n");
  211.  
  212.     return AS_PF_OK;
  213. }
  214.  
  215. /** Free a frame that is backed by the ELF backend.
  216.  *
  217.  * The address space area and page tables must be already locked.
  218.  *
  219.  * @param area Pointer to the address space area.
  220.  * @param page Page that is mapped to frame. Must be aligned to PAGE_SIZE.
  221.  * @param frame Frame to be released.
  222.  *
  223.  */
  224. void elf_frame_free(as_area_t *area, uintptr_t page, uintptr_t frame)
  225. {
  226.     elf_header_t *elf = area->backend_data.elf;
  227.     elf_segment_header_t *entry = area->backend_data.segment;
  228.     uintptr_t base;
  229.     index_t i;
  230.    
  231.     ASSERT((page >= entry->p_vaddr) &&
  232.         (page < entry->p_vaddr + entry->p_memsz));
  233.     i = (page - entry->p_vaddr) >> PAGE_WIDTH;
  234.     base = (uintptr_t) (((void *) elf) + entry->p_offset);
  235.     ASSERT(ALIGN_UP(base, FRAME_SIZE) == base);
  236.    
  237.     if (page + PAGE_SIZE <
  238.         ALIGN_UP(entry->p_vaddr + entry->p_filesz, PAGE_SIZE)) {
  239.         if (entry->p_flags & PF_W) {
  240.             /*
  241.              * Free the frame with the copy of writable segment
  242.              * data.
  243.              */
  244.             frame_free(frame);
  245.         }
  246.     } else {
  247.         /*
  248.          * The frame is either anonymous memory or the mixed case (i.e.
  249.          * lower part is backed by the ELF image and the upper is
  250.          * anonymous). In any case, a frame needs to be freed.
  251.          */
  252.         frame_free(frame);
  253.     }
  254. }
  255.  
  256. /** Share ELF image backed address space area.
  257.  *
  258.  * If the area is writable, then all mapped pages are duplicated in the pagemap.
  259.  * Otherwise only portions of the area that are not backed by the ELF image
  260.  * are put into the pagemap.
  261.  *
  262.  * The address space and address space area must be locked prior to the call.
  263.  *
  264.  * @param area Address space area.
  265.  */
  266. void elf_share(as_area_t *area)
  267. {
  268.     elf_segment_header_t *entry = area->backend_data.segment;
  269.     link_t *cur;
  270.     btree_node_t *leaf, *node;
  271.     uintptr_t start_anon = entry->p_vaddr + entry->p_filesz;
  272.  
  273.     /*
  274.      * Find the node in which to start linear search.
  275.      */
  276.     if (area->flags & AS_AREA_WRITE) {
  277.         node = list_get_instance(area->used_space.leaf_head.next,
  278.             btree_node_t, leaf_link);
  279.     } else {
  280.         (void) btree_search(&area->sh_info->pagemap, start_anon, &leaf);
  281.         node = btree_leaf_node_left_neighbour(&area->sh_info->pagemap,
  282.             leaf);
  283.         if (!node)
  284.             node = leaf;
  285.     }
  286.  
  287.     /*
  288.      * Copy used anonymous portions of the area to sh_info's page map.
  289.      */
  290.     mutex_lock(&area->sh_info->lock);
  291.     for (cur = &node->leaf_link; cur != &area->used_space.leaf_head;
  292.         cur = cur->next) {
  293.         int i;
  294.        
  295.         node = list_get_instance(cur, btree_node_t, leaf_link);
  296.        
  297.         for (i = 0; i < node->keys; i++) {
  298.             uintptr_t base = node->key[i];
  299.             count_t count = (count_t) node->value[i];
  300.             int j;
  301.            
  302.             /*
  303.              * Skip read-only areas of used space that are backed
  304.              * by the ELF image.
  305.              */
  306.             if (!(area->flags & AS_AREA_WRITE))
  307.                 if (base + count*PAGE_SIZE <= start_anon)
  308.                     continue;
  309.            
  310.             for (j = 0; j < count; j++) {
  311.                 pte_t *pte;
  312.            
  313.                 /*
  314.                  * Skip read-only pages that are backed by the
  315.                  * ELF image.
  316.                  */
  317.                 if (!(area->flags & AS_AREA_WRITE))
  318.                     if (base + (j + 1) * PAGE_SIZE <=
  319.                         start_anon)
  320.                         continue;
  321.                
  322.                 page_table_lock(area->as, false);
  323.                 pte = page_mapping_find(area->as,
  324.                     base + j * PAGE_SIZE);
  325.                 ASSERT(pte && PTE_VALID(pte) &&
  326.                     PTE_PRESENT(pte));
  327.                 btree_insert(&area->sh_info->pagemap,
  328.                     (base + j * PAGE_SIZE) - area->base,
  329.                     (void *) PTE_GET_FRAME(pte), NULL);
  330.                 page_table_unlock(area->as, false);
  331.  
  332.                 pfn_t pfn = ADDR2PFN(PTE_GET_FRAME(pte));
  333.                 frame_reference_add(pfn);
  334.             }
  335.                
  336.         }
  337.     }
  338.     mutex_unlock(&area->sh_info->lock);
  339. }
  340.  
  341. /** @}
  342.  */
  343.