Subversion Repositories HelenOS

Rev

Rev 3007 | Go to most recent revision | Blame | Compare with Previous | Last modification | View Log | Download | RSS feed

  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.     /* Check if the ELF image starts on a page boundary */
  104.     if (ALIGN_UP((uintptr_t)header, PAGE_SIZE) != (uintptr_t)header)
  105.         return EE_UNSUPPORTED;
  106.  
  107.     /* Walk through all segment headers and process them. */
  108.     for (i = 0; i < header->e_phnum; i++) {
  109.         elf_segment_header_t *seghdr;
  110.  
  111.         seghdr = &((elf_segment_header_t *)(((uint8_t *) header) +
  112.             header->e_phoff))[i];
  113.         rc = segment_header(seghdr, header, as);
  114.         if (rc != EE_OK)
  115.             return rc;
  116.     }
  117.  
  118.     /* Inspect all section headers and proccess them. */
  119.     for (i = 0; i < header->e_shnum; i++) {
  120.         elf_section_header_t *sechdr;
  121.  
  122.         sechdr = &((elf_section_header_t *)(((uint8_t *) header) +
  123.             header->e_shoff))[i];
  124.         rc = section_header(sechdr, header, as);
  125.         if (rc != EE_OK)
  126.             return rc;
  127.     }
  128.  
  129.     return EE_OK;
  130. }
  131.  
  132. /** Print error message according to error code.
  133.  *
  134.  * @param rc Return code returned by elf_load().
  135.  *
  136.  * @return NULL terminated description of error.
  137.  */
  138. char *elf_error(unsigned int rc)
  139. {
  140.     ASSERT(rc < sizeof(error_codes) / sizeof(char *));
  141.  
  142.     return error_codes[rc];
  143. }
  144.  
  145. /** Process segment header.
  146.  *
  147.  * @param entry Segment header.
  148.  * @param elf ELF header.
  149.  * @param as Address space into wich the ELF is being loaded.
  150.  *
  151.  * @return EE_OK on success, error code otherwise.
  152.  */
  153. static int segment_header(elf_segment_header_t *entry, elf_header_t *elf,
  154.     as_t *as)
  155. {
  156.     switch (entry->p_type) {
  157.     case PT_NULL:
  158.     case PT_PHDR:
  159.         break;
  160.     case PT_LOAD:
  161.         return load_segment(entry, elf, as);
  162.         break;
  163.     case PT_DYNAMIC:
  164.     case PT_INTERP:
  165.     case PT_SHLIB:
  166.     case PT_NOTE:
  167.     case PT_LOPROC:
  168.     case PT_HIPROC:
  169.     default:
  170.         return EE_UNSUPPORTED;
  171.         break;
  172.     }
  173.     return EE_OK;
  174. }
  175.  
  176. /** Load segment described by program header entry.
  177.  *
  178.  * @param entry Program header entry describing segment to be loaded.
  179.  * @param elf ELF header.
  180.  * @param as Address space into wich the ELF is being loaded.
  181.  *
  182.  * @return EE_OK on success, error code otherwise.
  183.  */
  184. int load_segment(elf_segment_header_t *entry, elf_header_t *elf, as_t *as)
  185. {
  186.     as_area_t *a;
  187.     int flags = 0;
  188.     mem_backend_data_t backend_data;
  189.     uintptr_t base;
  190.     size_t mem_sz;
  191.    
  192.     backend_data.elf = elf;
  193.     backend_data.segment = entry;
  194.  
  195.     if (entry->p_align > 1) {
  196.         if ((entry->p_offset % entry->p_align) !=
  197.             (entry->p_vaddr % entry->p_align)) {
  198.             return EE_INVALID;
  199.         }
  200.     }
  201.  
  202.     if (entry->p_flags & PF_X)
  203.         flags |= AS_AREA_EXEC;
  204.     if (entry->p_flags & PF_W)
  205.         flags |= AS_AREA_WRITE;
  206.     if (entry->p_flags & PF_R)
  207.         flags |= AS_AREA_READ;
  208.     flags |= AS_AREA_CACHEABLE;
  209.  
  210.     /*
  211.      * Align vaddr down, inserting a little "gap" at the beginning.
  212.      * Adjust area size, so that its end remains in place.
  213.      */
  214.     base = ALIGN_DOWN(entry->p_vaddr, PAGE_SIZE);
  215.     mem_sz = entry->p_memsz + (entry->p_vaddr - base);
  216.  
  217.     a = as_area_create(as, flags, mem_sz, base,
  218.         AS_AREA_ATTR_NONE, &elf_backend, &backend_data);
  219.     if (!a)
  220.         return EE_MEMORY;
  221.    
  222.     /*
  223.      * The segment will be mapped on demand by elf_page_fault().
  224.      */
  225.  
  226.     return EE_OK;
  227. }
  228.  
  229. /** Process section header.
  230.  *
  231.  * @param entry Segment header.
  232.  * @param elf ELF header.
  233.  * @param as Address space into wich the ELF is being loaded.
  234.  *
  235.  * @return EE_OK on success, error code otherwise.
  236.  */
  237. static int section_header(elf_section_header_t *entry, elf_header_t *elf,
  238.     as_t *as)
  239. {
  240.     switch (entry->sh_type) {
  241.     case SHT_PROGBITS:
  242.         if (entry->sh_flags & SHF_TLS) {
  243.             /* .tdata */
  244.         }
  245.         break;
  246.     case SHT_NOBITS:
  247.         if (entry->sh_flags & SHF_TLS) {
  248.             /* .tbss */
  249.         }
  250.         break;
  251.     default:
  252.         break;
  253.     }
  254.    
  255.     return EE_OK;
  256. }
  257.  
  258. /** @}
  259.  */
  260.