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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. /** @addtogroup generic
  31.  * @{
  32.  */
  33.  
  34. /**
  35.  * @file
  36.  * @brief   Kernel ELF loader.
  37.  */
  38.  
  39. #include <elf.h>
  40. #include <debug.h>
  41. #include <arch/types.h>
  42. #include <typedefs.h>
  43. #include <mm/as.h>
  44. #include <mm/frame.h>
  45. #include <mm/slab.h>
  46. #include <align.h>
  47. #include <memstr.h>
  48. #include <macros.h>
  49. #include <arch.h>
  50.  
  51. static char *error_codes[] = {
  52.     "no error",
  53.     "invalid image",
  54.     "address space error",
  55.     "incompatible image",
  56.     "unsupported image type",
  57.     "irrecoverable error"
  58. };
  59.  
  60. static int segment_header(elf_segment_header_t *entry, elf_header_t *elf, as_t *as);
  61. static int section_header(elf_section_header_t *entry, elf_header_t *elf, as_t *as);
  62. static int load_segment(elf_segment_header_t *entry, elf_header_t *elf, as_t *as);
  63.  
  64. /** ELF loader
  65.  *
  66.  * @param header Pointer to ELF header in memory
  67.  * @param as Created and properly mapped address space
  68.  * @return EE_OK on success
  69.  */
  70. int elf_load(elf_header_t *header, as_t * as)
  71. {
  72.     int i, rc;
  73.  
  74.     /* Identify ELF */
  75.     if (header->e_ident[EI_MAG0] != ELFMAG0 || header->e_ident[EI_MAG1] != ELFMAG1 ||
  76.         header->e_ident[EI_MAG2] != ELFMAG2 || header->e_ident[EI_MAG3] != ELFMAG3) {
  77.         return EE_INVALID;
  78.     }
  79.    
  80.     /* Identify ELF compatibility */
  81.     if (header->e_ident[EI_DATA] != ELF_DATA_ENCODING || header->e_machine != ELF_MACHINE ||
  82.         header->e_ident[EI_VERSION] != EV_CURRENT || header->e_version != EV_CURRENT ||
  83.         header->e_ident[EI_CLASS] != ELF_CLASS) {
  84.         return EE_INCOMPATIBLE;
  85.     }
  86.  
  87.     if (header->e_phentsize != sizeof(elf_segment_header_t))
  88.         return EE_INCOMPATIBLE;
  89.  
  90.     if (header->e_shentsize != sizeof(elf_section_header_t))
  91.         return EE_INCOMPATIBLE;
  92.  
  93.     /* Check if the object type is supported. */
  94.     if (header->e_type != ET_EXEC)
  95.         return EE_UNSUPPORTED;
  96.  
  97.     /* Walk through all segment headers and process them. */
  98.     for (i = 0; i < header->e_phnum; i++) {
  99.         rc = segment_header(&((elf_segment_header_t *)(((uint8_t *) header) + header->e_phoff))[i], header, as);
  100.         if (rc != EE_OK)
  101.             return rc;
  102.     }
  103.  
  104.     /* Inspect all section headers and proccess them. */
  105.     for (i = 0; i < header->e_shnum; i++) {
  106.         rc = section_header(&((elf_section_header_t *)(((uint8_t *) header) + header->e_shoff))[i], header, as);
  107.         if (rc != EE_OK)
  108.             return rc;
  109.     }
  110.  
  111.     return EE_OK;
  112. }
  113.  
  114. /** Print error message according to error code.
  115.  *
  116.  * @param rc Return code returned by elf_load().
  117.  *
  118.  * @return NULL terminated description of error.
  119.  */
  120. char *elf_error(int rc)
  121. {
  122.     ASSERT(rc < sizeof(error_codes)/sizeof(char *));
  123.  
  124.     return error_codes[rc];
  125. }
  126.  
  127. /** Process segment header.
  128.  *
  129.  * @param entry Segment header.
  130.  * @param elf ELF header.
  131.  * @param as Address space into wich the ELF is being loaded.
  132.  *
  133.  * @return EE_OK on success, error code otherwise.
  134.  */
  135. static int segment_header(elf_segment_header_t *entry, elf_header_t *elf, as_t *as)
  136. {
  137.     switch (entry->p_type) {
  138.         case PT_NULL:
  139.         case PT_PHDR:
  140.         break;
  141.         case PT_LOAD:
  142.         return load_segment(entry, elf, as);
  143.         break;
  144.         case PT_DYNAMIC:
  145.         case PT_INTERP:
  146.         case PT_SHLIB:
  147.         case PT_NOTE:
  148.         case PT_LOPROC:
  149.         case PT_HIPROC:
  150.         default:
  151.         return EE_UNSUPPORTED;
  152.         break;
  153.     }
  154.     return EE_OK;
  155. }
  156.  
  157. /** Load segment described by program header entry.
  158.  *
  159.  * @param entry Program header entry describing segment to be loaded.
  160.  * @param elf ELF header.
  161.  * @param as Address space into wich the ELF is being loaded.
  162.  *
  163.  * @return EE_OK on success, error code otherwise.
  164.  */
  165. int load_segment(elf_segment_header_t *entry, elf_header_t *elf, as_t *as)
  166. {
  167.     as_area_t *a;
  168.     int flags = 0;
  169.     mem_backend_data_t backend_data;
  170.    
  171.     backend_data.elf = elf;
  172.     backend_data.segment = entry;
  173.  
  174.     if (entry->p_align > 1) {
  175.         if ((entry->p_offset % entry->p_align) != (entry->p_vaddr % entry->p_align)) {
  176.             return EE_INVALID;
  177.         }
  178.     }
  179.  
  180.     if (entry->p_flags & PF_X)
  181.         flags |= AS_AREA_EXEC;
  182.     if (entry->p_flags & PF_W)
  183.         flags |= AS_AREA_WRITE;
  184.     if (entry->p_flags & PF_R)
  185.         flags |= AS_AREA_READ;
  186.     flags |= AS_AREA_CACHEABLE;
  187.  
  188.     /*
  189.      * Check if the virtual address starts on page boundary.
  190.      */
  191.     if (ALIGN_UP(entry->p_vaddr, PAGE_SIZE) != entry->p_vaddr)
  192.         return EE_UNSUPPORTED;
  193.  
  194.     a = as_area_create(as, flags, entry->p_memsz, entry->p_vaddr, AS_AREA_ATTR_NONE,
  195.         &elf_backend, &backend_data);
  196.     if (!a)
  197.         return EE_MEMORY;
  198.    
  199.     /*
  200.      * The segment will be mapped on demand by elf_page_fault().
  201.      */
  202.  
  203.     return EE_OK;
  204. }
  205.  
  206. /** Process section header.
  207.  *
  208.  * @param entry Segment header.
  209.  * @param elf ELF header.
  210.  * @param as Address space into wich the ELF is being loaded.
  211.  *
  212.  * @return EE_OK on success, error code otherwise.
  213.  */
  214. static int section_header(elf_section_header_t *entry, elf_header_t *elf, as_t *as)
  215. {
  216.     switch (entry->sh_type) {
  217.         default:
  218.         break;
  219.     }
  220.    
  221.     return EE_OK;
  222. }
  223.  
  224. /** @}
  225.  */
  226.