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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.  
  85.     if (!as_area_check_access(area, access))
  86.         return AS_PF_FAULT;
  87.  
  88.     ASSERT((addr >= entry->p_vaddr) &&
  89.         (addr < entry->p_vaddr + entry->p_memsz));
  90.     i = (addr - entry->p_vaddr) >> PAGE_WIDTH;
  91.     base = (uintptr_t) (((void *) elf) + entry->p_offset);
  92.     ASSERT(ALIGN_UP(base, FRAME_SIZE) == base);
  93.  
  94.     if (area->sh_info) {
  95.         bool found = false;
  96.  
  97.         /*
  98.          * The address space area is shared.
  99.          */
  100.          
  101.         mutex_lock(&area->sh_info->lock);
  102.         frame = (uintptr_t) btree_search(&area->sh_info->pagemap,
  103.             ALIGN_DOWN(addr, PAGE_SIZE) - area->base, &leaf);
  104.         if (!frame) {
  105.             int i;
  106.  
  107.             /*
  108.              * Workaround for valid NULL address.
  109.              */
  110.  
  111.             for (i = 0; i < leaf->keys; i++) {
  112.                 if (leaf->key[i] ==
  113.                     ALIGN_DOWN(addr, PAGE_SIZE)) {
  114.                     found = true;
  115.                     break;
  116.                 }
  117.             }
  118.         }
  119.         if (frame || found) {
  120.             frame_reference_add(ADDR2PFN(frame));
  121.             page_mapping_insert(AS, addr, frame,
  122.                 as_area_get_flags(area));
  123.             if (!used_space_insert(area,
  124.                 ALIGN_DOWN(addr, PAGE_SIZE), 1))
  125.                 panic("Could not insert used space.\n");
  126.             mutex_unlock(&area->sh_info->lock);
  127.             return AS_PF_OK;
  128.         }
  129.     }
  130.    
  131.     /*
  132.      * The area is either not shared or the pagemap does not contain the
  133.      * mapping.
  134.      */
  135.    
  136.     if (ALIGN_DOWN(addr, PAGE_SIZE) + PAGE_SIZE <
  137.         entry->p_vaddr + entry->p_filesz) {
  138.         /*
  139.          * Initialized portion of the segment. The memory is backed
  140.          * directly by the content of the ELF image. Pages are
  141.          * only copied if the segment is writable so that there
  142.          * can be more instantions of the same memory ELF image
  143.          * used at a time. Note that this could be later done
  144.          * as COW.
  145.          */
  146.         if (entry->p_flags & PF_W) {
  147.             frame = (uintptr_t)frame_alloc(ONE_FRAME, 0);
  148.             memcpy((void *) PA2KA(frame),
  149.                 (void *) (base + i * FRAME_SIZE), FRAME_SIZE);
  150.            
  151.             if (area->sh_info) {
  152.                 frame_reference_add(ADDR2PFN(frame));
  153.                 btree_insert(&area->sh_info->pagemap,
  154.                     ALIGN_DOWN(addr, PAGE_SIZE) - area->base,
  155.                     (void *) frame, leaf);
  156.             }
  157.  
  158.         } else {
  159.             frame = KA2PA(base + i*FRAME_SIZE);
  160.         }  
  161.     } else if (ALIGN_DOWN(addr, PAGE_SIZE) >=
  162.         ALIGN_UP(entry->p_vaddr + entry->p_filesz, PAGE_SIZE)) {
  163.         /*
  164.          * This is the uninitialized portion of the segment.
  165.          * It is not physically present in the ELF image.
  166.          * To resolve the situation, a frame must be allocated
  167.          * and cleared.
  168.          */
  169.         frame = (uintptr_t)frame_alloc(ONE_FRAME, 0);
  170.         memsetb(PA2KA(frame), FRAME_SIZE, 0);
  171.  
  172.         if (area->sh_info) {
  173.             frame_reference_add(ADDR2PFN(frame));
  174.             btree_insert(&area->sh_info->pagemap,
  175.                 ALIGN_DOWN(addr, PAGE_SIZE) - area->base,
  176.                 (void *) frame, leaf);
  177.         }
  178.  
  179.     } else {
  180.         size_t size;
  181.         /*
  182.          * The mixed case.
  183.          * The lower part is backed by the ELF image and
  184.          * the upper part is anonymous memory.
  185.          */
  186.         size = entry->p_filesz - (i<<PAGE_WIDTH);
  187.         frame = (uintptr_t)frame_alloc(ONE_FRAME, 0);
  188.         memsetb(PA2KA(frame) + size, FRAME_SIZE - size, 0);
  189.         memcpy((void *) PA2KA(frame), (void *) (base + i * FRAME_SIZE),
  190.             size);
  191.  
  192.         if (area->sh_info) {
  193.             frame_reference_add(ADDR2PFN(frame));
  194.             btree_insert(&area->sh_info->pagemap,
  195.                 ALIGN_DOWN(addr, PAGE_SIZE) - area->base,
  196.                 (void *) frame, leaf);
  197.         }
  198.  
  199.     }
  200.    
  201.     if (area->sh_info)
  202.         mutex_unlock(&area->sh_info->lock);
  203.    
  204.     page_mapping_insert(AS, addr, frame, as_area_get_flags(area));
  205.     if (!used_space_insert(area, ALIGN_DOWN(addr, PAGE_SIZE), 1))
  206.         panic("Could not insert used space.\n");
  207.  
  208.     return AS_PF_OK;
  209. }
  210.  
  211. /** Free a frame that is backed by the ELF backend.
  212.  *
  213.  * The address space area and page tables must be already locked.
  214.  *
  215.  * @param area Pointer to the address space area.
  216.  * @param page Page that is mapped to frame. Must be aligned to PAGE_SIZE.
  217.  * @param frame Frame to be released.
  218.  *
  219.  */
  220. void elf_frame_free(as_area_t *area, uintptr_t page, uintptr_t frame)
  221. {
  222.     elf_header_t *elf = area->backend_data.elf;
  223.     elf_segment_header_t *entry = area->backend_data.segment;
  224.     uintptr_t base;
  225.     index_t i;
  226.    
  227.     ASSERT((page >= entry->p_vaddr) &&
  228.         (page < entry->p_vaddr + entry->p_memsz));
  229.     i = (page - entry->p_vaddr) >> PAGE_WIDTH;
  230.     base = (uintptr_t) (((void *) elf) + entry->p_offset);
  231.     ASSERT(ALIGN_UP(base, FRAME_SIZE) == base);
  232.    
  233.     if (page + PAGE_SIZE <
  234.         ALIGN_UP(entry->p_vaddr + entry->p_filesz, PAGE_SIZE)) {
  235.         if (entry->p_flags & PF_W) {
  236.             /*
  237.              * Free the frame with the copy of writable segment
  238.              * data.
  239.              */
  240.             frame_free(frame);
  241. #ifdef CONFIG_VIRT_IDX_DCACHE
  242.                 dcache_flush_frame(page, frame);
  243. #endif
  244.         }
  245.     } else {
  246.         /*
  247.          * The frame is either anonymous memory or the mixed case (i.e.
  248.          * lower part is backed by the ELF image and the upper is
  249.          * anonymous). In any case, a frame needs to be freed.
  250.          */
  251.         frame_free(frame);
  252. #ifdef CONFIG_VIRT_IDX_DCACHE
  253.             dcache_flush_frame(page, frame);
  254. #endif
  255.     }
  256. }
  257.  
  258. /** Share ELF image backed address space area.
  259.  *
  260.  * If the area is writable, then all mapped pages are duplicated in the pagemap.
  261.  * Otherwise only portions of the area that are not backed by the ELF image
  262.  * are put into the pagemap.
  263.  *
  264.  * The address space and address space area must be locked prior to the call.
  265.  *
  266.  * @param area Address space area.
  267.  */
  268. void elf_share(as_area_t *area)
  269. {
  270.     elf_segment_header_t *entry = area->backend_data.segment;
  271.     link_t *cur;
  272.     btree_node_t *leaf, *node;
  273.     uintptr_t start_anon = entry->p_vaddr + entry->p_filesz;
  274.  
  275.     /*
  276.      * Find the node in which to start linear search.
  277.      */
  278.     if (area->flags & AS_AREA_WRITE) {
  279.         node = list_get_instance(area->used_space.leaf_head.next,
  280.             btree_node_t, leaf_link);
  281.     } else {
  282.         (void) btree_search(&area->sh_info->pagemap, start_anon, &leaf);
  283.         node = btree_leaf_node_left_neighbour(&area->sh_info->pagemap,
  284.             leaf);
  285.         if (!node)
  286.             node = leaf;
  287.     }
  288.  
  289.     /*
  290.      * Copy used anonymous portions of the area to sh_info's page map.
  291.      */
  292.     mutex_lock(&area->sh_info->lock);
  293.     for (cur = &node->leaf_link; cur != &area->used_space.leaf_head;
  294.         cur = cur->next) {
  295.         int i;
  296.        
  297.         node = list_get_instance(cur, btree_node_t, leaf_link);
  298.        
  299.         for (i = 0; i < node->keys; i++) {
  300.             uintptr_t base = node->key[i];
  301.             count_t count = (count_t) node->value[i];
  302.             int j;
  303.            
  304.             /*
  305.              * Skip read-only areas of used space that are backed
  306.              * by the ELF image.
  307.              */
  308.             if (!(area->flags & AS_AREA_WRITE))
  309.                 if (base + count*PAGE_SIZE <= start_anon)
  310.                     continue;
  311.            
  312.             for (j = 0; j < count; j++) {
  313.                 pte_t *pte;
  314.            
  315.                 /*
  316.                  * Skip read-only pages that are backed by the
  317.                  * ELF image.
  318.                  */
  319.                 if (!(area->flags & AS_AREA_WRITE))
  320.                     if (base + (j + 1) * PAGE_SIZE <=
  321.                         start_anon)
  322.                         continue;
  323.                
  324.                 page_table_lock(area->as, false);
  325.                 pte = page_mapping_find(area->as,
  326.                     base + j * PAGE_SIZE);
  327.                 ASSERT(pte && PTE_VALID(pte) &&
  328.                     PTE_PRESENT(pte));
  329.                 btree_insert(&area->sh_info->pagemap,
  330.                     (base + j * PAGE_SIZE) - area->base,
  331.                     (void *) PTE_GET_FRAME(pte), NULL);
  332.                 page_table_unlock(area->as, false);
  333.  
  334.                 pfn_t pfn = ADDR2PFN(PTE_GET_FRAME(pte));
  335.                 frame_reference_add(pfn);
  336.             }
  337.                
  338.         }
  339.     }
  340.     mutex_unlock(&area->sh_info->lock);
  341. }
  342.  
  343. /** @}
  344.  */
  345.  
  346.