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  1. /*
  2.  * Copyright (C) 2006 Sergey Bondari
  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. #include <elf.h>
  30. #include <debug.h>
  31. #include <arch/types.h>
  32. #include <typedefs.h>
  33. #include <mm/as.h>
  34. #include <mm/frame.h>
  35. #include <mm/slab.h>
  36. #include <align.h>
  37. #include <memstr.h>
  38. #include <macros.h>
  39.  
  40. static char *error_codes[] = {
  41.     "no error",
  42.     "invalid image",
  43.     "address space error",
  44.     "incompatible image",
  45.     "unsupported image type",
  46.     "irrecoverable error"
  47. };
  48.  
  49. static int segment_header(elf_segment_header_t *entry, elf_header_t *elf, as_t *as);
  50. static int section_header(elf_section_header_t *entry, elf_header_t *elf, as_t *as);
  51. static int load_segment(elf_segment_header_t *entry, elf_header_t *elf, as_t *as);
  52.  
  53. /** ELF loader
  54.  *
  55.  * @param header Pointer to ELF header in memory
  56.  * @param as Created and properly mapped address space
  57.  * @return EE_OK on success
  58.  */
  59. int elf_load(elf_header_t *header, as_t * as)
  60. {
  61.     int i, rc;
  62.  
  63.     /* Identify ELF */
  64.     if (header->e_ident[EI_MAG0] != ELFMAG0 || header->e_ident[EI_MAG1] != ELFMAG1 ||
  65.         header->e_ident[EI_MAG2] != ELFMAG2 || header->e_ident[EI_MAG3] != ELFMAG3) {
  66.         return EE_INVALID;
  67.     }
  68.    
  69.     /* Identify ELF compatibility */
  70.     if (header->e_ident[EI_DATA] != ELF_DATA_ENCODING || header->e_machine != ELF_MACHINE ||
  71.         header->e_ident[EI_VERSION] != EV_CURRENT || header->e_version != EV_CURRENT ||
  72.         header->e_ident[EI_CLASS] != ELF_CLASS) {
  73.         return EE_INCOMPATIBLE;
  74.     }
  75.  
  76.     if (header->e_phentsize != sizeof(elf_segment_header_t))
  77.         return EE_INCOMPATIBLE;
  78.  
  79.     if (header->e_shentsize != sizeof(elf_section_header_t))
  80.         return EE_INCOMPATIBLE;
  81.  
  82.     /* Check if the object type is supported. */
  83.     if (header->e_type != ET_EXEC)
  84.         return EE_UNSUPPORTED;
  85.  
  86.     /* Walk through all segment headers and process them. */
  87.     for (i = 0; i < header->e_phnum; i++) {
  88.         rc = segment_header(&((elf_segment_header_t *)(((__u8 *) header) + header->e_phoff))[i], header, as);
  89.         if (rc != EE_OK)
  90.             return rc;
  91.     }
  92.  
  93.     /* Inspect all section headers and proccess them. */
  94.     for (i = 0; i < header->e_shnum; i++) {
  95.         rc = section_header(&((elf_section_header_t *)(((__u8 *) header) + header->e_shoff))[i], header, as);
  96.         if (rc != EE_OK)
  97.             return rc;
  98.     }
  99.  
  100.     return EE_OK;
  101. }
  102.  
  103. /** Print error message according to error code.
  104.  *
  105.  * @param rc Return code returned by elf_load().
  106.  *
  107.  * @return NULL terminated description of error.
  108.  */
  109. char *elf_error(int rc)
  110. {
  111.     ASSERT(rc < sizeof(error_codes)/sizeof(char *));
  112.  
  113.     return error_codes[rc];
  114. }
  115.  
  116. /** Process segment header.
  117.  *
  118.  * @param entry Segment header.
  119.  * @param elf ELF header.
  120.  * @param as Address space into wich the ELF is being loaded.
  121.  *
  122.  * @return EE_OK on success, error code otherwise.
  123.  */
  124. static int segment_header(elf_segment_header_t *entry, elf_header_t *elf, as_t *as)
  125. {
  126.     switch (entry->p_type) {
  127.         case PT_NULL:
  128.         case PT_PHDR:
  129.         break;
  130.         case PT_LOAD:
  131.         return load_segment(entry, elf, as);
  132.         break;
  133.         case PT_DYNAMIC:
  134.         case PT_INTERP:
  135.         case PT_SHLIB:
  136.         case PT_NOTE:
  137.         case PT_LOPROC:
  138.         case PT_HIPROC:
  139.         default:
  140.         return EE_UNSUPPORTED;
  141.         break;
  142.     }
  143.     return EE_OK;
  144. }
  145.  
  146. /** Load segment described by program header entry.
  147.  *
  148.  * @param entry Program header entry describing segment to be loaded.
  149.  * @param elf ELF header.
  150.  * @parma as Address space into wich the ELF is being loaded.
  151.  *
  152.  * @return EE_OK on success, error code otherwise.
  153.  */
  154. int load_segment(elf_segment_header_t *entry, elf_header_t *elf, as_t *as)
  155. {
  156.     as_area_t *a;
  157.     int i, flags = 0;
  158.     size_t segment_size;
  159.     __u8 *segment;
  160.  
  161.     if (entry->p_align > 1) {
  162.         if ((entry->p_offset % entry->p_align) != (entry->p_vaddr % entry->p_align)) {
  163.             return EE_INVALID;
  164.         }
  165.     }
  166.  
  167.     if (entry->p_flags & PF_X)
  168.         flags |= AS_AREA_EXEC;
  169.     if (entry->p_flags & PF_W)
  170.         flags |= AS_AREA_WRITE;
  171.     if (entry->p_flags & PF_R)
  172.         flags |= AS_AREA_READ;
  173.  
  174.     /*
  175.      * Check if the virtual address starts on page boundary.
  176.      */
  177.     if (ALIGN_UP(entry->p_vaddr, PAGE_SIZE) != entry->p_vaddr)
  178.         return EE_UNSUPPORTED;
  179.  
  180.     segment_size = ALIGN_UP(max(entry->p_filesz, entry->p_memsz), PAGE_SIZE);
  181.     if ((entry->p_flags & PF_W)) {
  182.         /* If writable, copy data (should be COW in the future) */
  183.         segment = malloc(segment_size, 0);
  184.         memsetb((__address) (segment + entry->p_filesz), segment_size - entry->p_filesz, 0);
  185.         memcpy(segment, (void *) (((__address) elf) + entry->p_offset), entry->p_filesz);
  186.     } else /* Map identically original data */
  187.         segment = ((void *) elf) + entry->p_offset;
  188.  
  189.     a = as_area_create(as, flags, entry->p_memsz, entry->p_vaddr);
  190.     if (!a)
  191.         return EE_MEMORY;
  192.    
  193.     for (i = 0; i < SIZE2FRAMES(entry->p_filesz); i++) {
  194.         as_set_mapping(as, entry->p_vaddr + i*PAGE_SIZE, KA2PA(((__address) segment) + i*PAGE_SIZE));
  195.     }
  196.    
  197.     return EE_OK;
  198. }
  199.  
  200. /** Process section header.
  201.  *
  202.  * @param entry Segment header.
  203.  * @param elf ELF header.
  204.  * @param as Address space into wich the ELF is being loaded.
  205.  *
  206.  * @return EE_OK on success, error code otherwise.
  207.  */
  208. static int section_header(elf_section_header_t *entry, elf_header_t *elf, as_t *as)
  209. {
  210.     switch (entry->sh_type) {
  211.         default:
  212.         break;
  213.     }
  214.    
  215.     return EE_OK;
  216. }
  217.