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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 <lib/elf.h>
  40. #include <debug.h>
  41. #include <arch/types.h>
  42. #include <mm/as.h>
  43. #include <mm/frame.h>
  44. #include <mm/slab.h>
  45. #include <align.h>
  46. #include <memstr.h>
  47. #include <macros.h>
  48. #include <arch.h>
  49.  
  50. static char *error_codes[] = {
  51.     "no error",
  52.     "invalid image",
  53.     "address space error",
  54.     "incompatible image",
  55.     "unsupported image type",
  56.     "irrecoverable error"
  57. };
  58.  
  59. static int segment_header(elf_segment_header_t *entry, elf_header_t *elf,
  60.     as_t *as);
  61. static int section_header(elf_section_header_t *entry, elf_header_t *elf,
  62.     as_t *as);
  63. static int load_segment(elf_segment_header_t *entry, elf_header_t *elf,
  64.     as_t *as);
  65.  
  66. /** ELF loader
  67.  *
  68.  * @param header Pointer to ELF header in memory
  69.  * @param as Created and properly mapped address space
  70.  * @return EE_OK on success
  71.  */
  72. unsigned int elf_load(elf_header_t *header, as_t * as)
  73. {
  74.     int i, rc;
  75.  
  76.     /* Identify ELF */
  77.     if (header->e_ident[EI_MAG0] != ELFMAG0 ||
  78.         header->e_ident[EI_MAG1] != ELFMAG1 ||
  79.         header->e_ident[EI_MAG2] != ELFMAG2 ||
  80.         header->e_ident[EI_MAG3] != ELFMAG3) {
  81.         return EE_INVALID;
  82.     }
  83.    
  84.     /* Identify ELF compatibility */
  85.     if (header->e_ident[EI_DATA] != ELF_DATA_ENCODING ||
  86.         header->e_machine != ELF_MACHINE ||
  87.         header->e_ident[EI_VERSION] != EV_CURRENT ||
  88.         header->e_version != EV_CURRENT ||
  89.         header->e_ident[EI_CLASS] != ELF_CLASS) {
  90.         return EE_INCOMPATIBLE;
  91.     }
  92.  
  93.     if (header->e_phentsize != sizeof(elf_segment_header_t))
  94.         return EE_INCOMPATIBLE;
  95.  
  96.     if (header->e_shentsize != sizeof(elf_section_header_t))
  97.         return EE_INCOMPATIBLE;
  98.  
  99.     /* Check if the object type is supported. */
  100.     if (header->e_type != ET_EXEC)
  101.         return EE_UNSUPPORTED;
  102.  
  103.     /* Walk through all segment headers and process them. */
  104.     for (i = 0; i < header->e_phnum; i++) {
  105.         elf_segment_header_t *seghdr;
  106.  
  107.         seghdr = &((elf_segment_header_t *)(((uint8_t *) header) +
  108.             header->e_phoff))[i];
  109.         rc = segment_header(seghdr, header, as);
  110.         if (rc != EE_OK)
  111.             return rc;
  112.     }
  113.  
  114.     /* Inspect all section headers and proccess them. */
  115.     for (i = 0; i < header->e_shnum; i++) {
  116.         elf_section_header_t *sechdr;
  117.  
  118.         sechdr = &((elf_section_header_t *)(((uint8_t *) header) +
  119.             header->e_shoff))[i];
  120.         rc = section_header(sechdr, header, as);
  121.         if (rc != EE_OK)
  122.             return rc;
  123.     }
  124.  
  125.     return EE_OK;
  126. }
  127.  
  128. /** Print error message according to error code.
  129.  *
  130.  * @param rc Return code returned by elf_load().
  131.  *
  132.  * @return NULL terminated description of error.
  133.  */
  134. char *elf_error(unsigned int rc)
  135. {
  136.     ASSERT(rc < sizeof(error_codes) / sizeof(char *));
  137.  
  138.     return error_codes[rc];
  139. }
  140.  
  141. /** Process segment header.
  142.  *
  143.  * @param entry Segment header.
  144.  * @param elf ELF header.
  145.  * @param as Address space into wich the ELF is being loaded.
  146.  *
  147.  * @return EE_OK on success, error code otherwise.
  148.  */
  149. static int segment_header(elf_segment_header_t *entry, elf_header_t *elf,
  150.     as_t *as)
  151. {
  152.     switch (entry->p_type) {
  153.     case PT_NULL:
  154.     case PT_PHDR:
  155.         break;
  156.     case PT_LOAD:
  157.         return load_segment(entry, elf, as);
  158.         break;
  159.     case PT_DYNAMIC:
  160.     case PT_INTERP:
  161.     case PT_SHLIB:
  162.     case PT_NOTE:
  163.     case PT_LOPROC:
  164.     case PT_HIPROC:
  165.     default:
  166.         return EE_UNSUPPORTED;
  167.         break;
  168.     }
  169.     return EE_OK;
  170. }
  171.  
  172. /** Load segment described by program header entry.
  173.  *
  174.  * @param entry Program header entry describing segment to be loaded.
  175.  * @param elf ELF header.
  176.  * @param as Address space into wich the ELF is being loaded.
  177.  *
  178.  * @return EE_OK on success, error code otherwise.
  179.  */
  180. int load_segment(elf_segment_header_t *entry, elf_header_t *elf, as_t *as)
  181. {
  182.     as_area_t *a;
  183.     int flags = 0;
  184.     mem_backend_data_t backend_data;
  185.    
  186.     backend_data.elf = elf;
  187.     backend_data.segment = entry;
  188.  
  189.     if (entry->p_align > 1) {
  190.         if ((entry->p_offset % entry->p_align) !=
  191.             (entry->p_vaddr % entry->p_align)) {
  192.             return EE_INVALID;
  193.         }
  194.     }
  195.  
  196.     if (entry->p_flags & PF_X)
  197.         flags |= AS_AREA_EXEC;
  198.     if (entry->p_flags & PF_W)
  199.         flags |= AS_AREA_WRITE;
  200.     if (entry->p_flags & PF_R)
  201.         flags |= AS_AREA_READ;
  202.     flags |= AS_AREA_CACHEABLE;
  203.  
  204.     /*
  205.      * Check if the virtual address starts on page boundary.
  206.      */
  207.     if (ALIGN_UP(entry->p_vaddr, PAGE_SIZE) != entry->p_vaddr)
  208.         return EE_UNSUPPORTED;
  209.  
  210.     a = as_area_create(as, flags, entry->p_memsz, entry->p_vaddr,
  211.         AS_AREA_ATTR_NONE, &elf_backend, &backend_data);
  212.     if (!a)
  213.         return EE_MEMORY;
  214.    
  215.     /*
  216.      * The segment will be mapped on demand by elf_page_fault().
  217.      */
  218.  
  219.     return EE_OK;
  220. }
  221.  
  222. /** Process section header.
  223.  *
  224.  * @param entry Segment header.
  225.  * @param elf ELF header.
  226.  * @param as Address space into wich the ELF is being loaded.
  227.  *
  228.  * @return EE_OK on success, error code otherwise.
  229.  */
  230. static int section_header(elf_section_header_t *entry, elf_header_t *elf,
  231.     as_t *as)
  232. {
  233.     switch (entry->sh_type) {
  234.     case SHT_PROGBITS:
  235.         if (entry->sh_flags & SHF_TLS) {
  236.             /* .tdata */
  237.         }
  238.         break;
  239.     case SHT_NOBITS:
  240.         if (entry->sh_flags & SHF_TLS) {
  241.             /* .tbss */
  242.         }
  243.         break;
  244.     default:
  245.         break;
  246.     }
  247.    
  248.     return EE_OK;
  249. }
  250.  
  251. /** @}
  252.  */
  253.