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  1. /*
  2.  * Copyright (C) 2006 Sergey Bondari
  3.  * Copyright (C) 2006 Jakub Jermar
  4.  * All rights reserved.
  5.  *
  6.  * Redistribution and use in source and binary forms, with or without
  7.  * modification, are permitted provided that the following conditions
  8.  * are met:
  9.  *
  10.  * - Redistributions of source code must retain the above copyright
  11.  *   notice, this list of conditions and the following disclaimer.
  12.  * - Redistributions in binary form must reproduce the above copyright
  13.  *   notice, this list of conditions and the following disclaimer in the
  14.  *   documentation and/or other materials provided with the distribution.
  15.  * - The name of the author may not be used to endorse or promote products
  16.  *   derived from this software without specific prior written permission.
  17.  *
  18.  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
  19.  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
  20.  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
  21.  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
  22.  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
  23.  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  24.  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  25.  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  26.  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
  27.  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  28.  */
  29.  
  30. /**
  31.  * @file    elf.c
  32.  * @brief   Kernel ELF loader.
  33.  */
  34.  
  35. #include <elf.h>
  36. #include <debug.h>
  37. #include <arch/types.h>
  38. #include <typedefs.h>
  39. #include <mm/as.h>
  40. #include <mm/frame.h>
  41. #include <mm/slab.h>
  42. #include <align.h>
  43. #include <memstr.h>
  44. #include <macros.h>
  45. #include <arch.h>
  46.  
  47. static char *error_codes[] = {
  48.     "no error",
  49.     "invalid image",
  50.     "address space error",
  51.     "incompatible image",
  52.     "unsupported image type",
  53.     "irrecoverable error"
  54. };
  55.  
  56. static int segment_header(elf_segment_header_t *entry, elf_header_t *elf, as_t *as);
  57. static int section_header(elf_section_header_t *entry, elf_header_t *elf, as_t *as);
  58. static int load_segment(elf_segment_header_t *entry, elf_header_t *elf, as_t *as);
  59.  
  60. /** ELF loader
  61.  *
  62.  * @param header Pointer to ELF header in memory
  63.  * @param as Created and properly mapped address space
  64.  * @return EE_OK on success
  65.  */
  66. int elf_load(elf_header_t *header, as_t * as)
  67. {
  68.     int i, rc;
  69.  
  70.     /* Identify ELF */
  71.     if (header->e_ident[EI_MAG0] != ELFMAG0 || header->e_ident[EI_MAG1] != ELFMAG1 ||
  72.         header->e_ident[EI_MAG2] != ELFMAG2 || header->e_ident[EI_MAG3] != ELFMAG3) {
  73.         return EE_INVALID;
  74.     }
  75.    
  76.     /* Identify ELF compatibility */
  77.     if (header->e_ident[EI_DATA] != ELF_DATA_ENCODING || header->e_machine != ELF_MACHINE ||
  78.         header->e_ident[EI_VERSION] != EV_CURRENT || header->e_version != EV_CURRENT ||
  79.         header->e_ident[EI_CLASS] != ELF_CLASS) {
  80.         return EE_INCOMPATIBLE;
  81.     }
  82.  
  83.     if (header->e_phentsize != sizeof(elf_segment_header_t))
  84.         return EE_INCOMPATIBLE;
  85.  
  86.     if (header->e_shentsize != sizeof(elf_section_header_t))
  87.         return EE_INCOMPATIBLE;
  88.  
  89.     /* Check if the object type is supported. */
  90.     if (header->e_type != ET_EXEC)
  91.         return EE_UNSUPPORTED;
  92.  
  93.     /* Walk through all segment headers and process them. */
  94.     for (i = 0; i < header->e_phnum; i++) {
  95.         rc = segment_header(&((elf_segment_header_t *)(((__u8 *) header) + header->e_phoff))[i], header, as);
  96.         if (rc != EE_OK)
  97.             return rc;
  98.     }
  99.  
  100.     /* Inspect all section headers and proccess them. */
  101.     for (i = 0; i < header->e_shnum; i++) {
  102.         rc = section_header(&((elf_section_header_t *)(((__u8 *) header) + header->e_shoff))[i], header, as);
  103.         if (rc != EE_OK)
  104.             return rc;
  105.     }
  106.  
  107.     return EE_OK;
  108. }
  109.  
  110. /** Print error message according to error code.
  111.  *
  112.  * @param rc Return code returned by elf_load().
  113.  *
  114.  * @return NULL terminated description of error.
  115.  */
  116. char *elf_error(int rc)
  117. {
  118.     ASSERT(rc < sizeof(error_codes)/sizeof(char *));
  119.  
  120.     return error_codes[rc];
  121. }
  122.  
  123. /** Process segment header.
  124.  *
  125.  * @param entry Segment header.
  126.  * @param elf ELF header.
  127.  * @param as Address space into wich the ELF is being loaded.
  128.  *
  129.  * @return EE_OK on success, error code otherwise.
  130.  */
  131. static int segment_header(elf_segment_header_t *entry, elf_header_t *elf, as_t *as)
  132. {
  133.     switch (entry->p_type) {
  134.         case PT_NULL:
  135.         case PT_PHDR:
  136.         break;
  137.         case PT_LOAD:
  138.         return load_segment(entry, elf, as);
  139.         break;
  140.         case PT_DYNAMIC:
  141.         case PT_INTERP:
  142.         case PT_SHLIB:
  143.         case PT_NOTE:
  144.         case PT_LOPROC:
  145.         case PT_HIPROC:
  146.         default:
  147.         return EE_UNSUPPORTED;
  148.         break;
  149.     }
  150.     return EE_OK;
  151. }
  152.  
  153. /** Load segment described by program header entry.
  154.  *
  155.  * @param entry Program header entry describing segment to be loaded.
  156.  * @param elf ELF header.
  157.  * @param as Address space into wich the ELF is being loaded.
  158.  *
  159.  * @return EE_OK on success, error code otherwise.
  160.  */
  161. int load_segment(elf_segment_header_t *entry, elf_header_t *elf, as_t *as)
  162. {
  163.     as_area_t *a;
  164.     int flags = 0;
  165.     mem_backend_data_t backend_data;
  166.    
  167.     backend_data.elf = elf;
  168.     backend_data.segment = entry;
  169.  
  170.     if (entry->p_align > 1) {
  171.         if ((entry->p_offset % entry->p_align) != (entry->p_vaddr % entry->p_align)) {
  172.             return EE_INVALID;
  173.         }
  174.     }
  175.  
  176.     if (entry->p_flags & PF_X)
  177.         flags |= AS_AREA_EXEC;
  178.     if (entry->p_flags & PF_W)
  179.         flags |= AS_AREA_WRITE;
  180.     if (entry->p_flags & PF_R)
  181.         flags |= AS_AREA_READ;
  182.     flags |= AS_AREA_CACHEABLE;
  183.  
  184.     /*
  185.      * Check if the virtual address starts on page boundary.
  186.      */
  187.     if (ALIGN_UP(entry->p_vaddr, PAGE_SIZE) != entry->p_vaddr)
  188.         return EE_UNSUPPORTED;
  189.  
  190.     a = as_area_create(as, flags, entry->p_memsz, entry->p_vaddr, AS_AREA_ATTR_NONE,
  191.         &elf_backend, &backend_data);
  192.     if (!a)
  193.         return EE_MEMORY;
  194.    
  195.     /*
  196.      * The segment will be mapped on demand by elf_page_fault().
  197.      */
  198.  
  199.     return EE_OK;
  200. }
  201.  
  202. /** Process section header.
  203.  *
  204.  * @param entry Segment header.
  205.  * @param elf ELF header.
  206.  * @param as Address space into wich the ELF is being loaded.
  207.  *
  208.  * @return EE_OK on success, error code otherwise.
  209.  */
  210. static int section_header(elf_section_header_t *entry, elf_header_t *elf, as_t *as)
  211. {
  212.     switch (entry->sh_type) {
  213.         default:
  214.         break;
  215.     }
  216.    
  217.     return EE_OK;
  218. }
  219.