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