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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, int flags);
  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.  * @param flags A combination of ELD_F_*
  71.  * @return EE_OK on success
  72.  */
  73. unsigned int elf_load(elf_header_t *header, as_t * as, int flags)
  74. {
  75.     int i, rc;
  76.  
  77.     /* Identify ELF */
  78.     if (header->e_ident[EI_MAG0] != ELFMAG0 ||
  79.         header->e_ident[EI_MAG1] != ELFMAG1 ||
  80.         header->e_ident[EI_MAG2] != ELFMAG2 ||
  81.         header->e_ident[EI_MAG3] != ELFMAG3) {
  82.         return EE_INVALID;
  83.     }
  84.    
  85.     /* Identify ELF compatibility */
  86.     if (header->e_ident[EI_DATA] != ELF_DATA_ENCODING ||
  87.         header->e_machine != ELF_MACHINE ||
  88.         header->e_ident[EI_VERSION] != EV_CURRENT ||
  89.         header->e_version != EV_CURRENT ||
  90.         header->e_ident[EI_CLASS] != ELF_CLASS) {
  91.         return EE_INCOMPATIBLE;
  92.     }
  93.  
  94.     if (header->e_phentsize != sizeof(elf_segment_header_t))
  95.         return EE_INCOMPATIBLE;
  96.  
  97.     if (header->e_shentsize != sizeof(elf_section_header_t))
  98.         return EE_INCOMPATIBLE;
  99.  
  100.     /* Check if the object type is supported. */
  101.     if (header->e_type != ET_EXEC)
  102.         return EE_UNSUPPORTED;
  103.  
  104.     /* Check if the ELF image starts on a page boundary */
  105.     if (ALIGN_UP((uintptr_t)header, PAGE_SIZE) != (uintptr_t)header)
  106.         return EE_UNSUPPORTED;
  107.  
  108.     /* Walk through all segment headers and process them. */
  109.     for (i = 0; i < header->e_phnum; i++) {
  110.         elf_segment_header_t *seghdr;
  111.  
  112.         seghdr = &((elf_segment_header_t *)(((uint8_t *) header) +
  113.             header->e_phoff))[i];
  114.         rc = segment_header(seghdr, header, as, flags);
  115.         if (rc != EE_OK)
  116.             return rc;
  117.     }
  118.  
  119.     /* Inspect all section headers and proccess them. */
  120.     for (i = 0; i < header->e_shnum; i++) {
  121.         elf_section_header_t *sechdr;
  122.  
  123.         sechdr = &((elf_section_header_t *)(((uint8_t *) header) +
  124.             header->e_shoff))[i];
  125.         rc = section_header(sechdr, header, as);
  126.         if (rc != EE_OK)
  127.             return rc;
  128.     }
  129.  
  130.     return EE_OK;
  131. }
  132.  
  133. /** Print error message according to error code.
  134.  *
  135.  * @param rc Return code returned by elf_load().
  136.  *
  137.  * @return NULL terminated description of error.
  138.  */
  139. char *elf_error(unsigned int rc)
  140. {
  141.     ASSERT(rc < sizeof(error_codes) / sizeof(char *));
  142.  
  143.     return error_codes[rc];
  144. }
  145.  
  146. /** Process segment header.
  147.  *
  148.  * @param entry Segment header.
  149.  * @param elf ELF header.
  150.  * @param as Address space into wich the ELF is being loaded.
  151.  *
  152.  * @return EE_OK on success, error code otherwise.
  153.  */
  154. static int segment_header(elf_segment_header_t *entry, elf_header_t *elf,
  155.     as_t *as, int flags)
  156. {
  157.     char *interp;
  158.  
  159.     switch (entry->p_type) {
  160.     case PT_NULL:
  161.     case PT_PHDR:
  162.         break;
  163.     case PT_LOAD:
  164.         return load_segment(entry, elf, as);
  165.         break;
  166.     case PT_DYNAMIC:
  167.     case PT_INTERP:
  168.         interp = (char *)elf + entry->p_offset;
  169.         /* FIXME */
  170.         /*if (memcmp((uintptr_t)interp, (uintptr_t)ELF_INTERP_ZSTR,
  171.             ELF_INTERP_ZLEN) != 0) {
  172.             return EE_UNSUPPORTED;
  173.         }*/
  174.         if ((flags & ELD_F_LOADER) == 0) {
  175.             return EE_LOADER;
  176.         }
  177.         break;
  178.     case PT_SHLIB:
  179.     case PT_NOTE:
  180.     case PT_LOPROC:
  181.     case PT_HIPROC:
  182.     default:
  183.         return EE_UNSUPPORTED;
  184.         break;
  185.     }
  186.     return EE_OK;
  187. }
  188.  
  189. /** Load segment described by program header entry.
  190.  *
  191.  * @param entry Program header entry describing segment to be loaded.
  192.  * @param elf ELF header.
  193.  * @param as Address space into wich the ELF is being loaded.
  194.  *
  195.  * @return EE_OK on success, error code otherwise.
  196.  */
  197. int load_segment(elf_segment_header_t *entry, elf_header_t *elf, as_t *as)
  198. {
  199.     as_area_t *a;
  200.     int flags = 0;
  201.     mem_backend_data_t backend_data;
  202.     uintptr_t base;
  203.     size_t mem_sz;
  204.    
  205.     backend_data.elf = elf;
  206.     backend_data.segment = entry;
  207.  
  208.     if (entry->p_align > 1) {
  209.         if ((entry->p_offset % entry->p_align) !=
  210.             (entry->p_vaddr % entry->p_align)) {
  211.             return EE_INVALID;
  212.         }
  213.     }
  214.  
  215.     if (entry->p_flags & PF_X)
  216.         flags |= AS_AREA_EXEC;
  217.     if (entry->p_flags & PF_W)
  218.         flags |= AS_AREA_WRITE;
  219.     if (entry->p_flags & PF_R)
  220.         flags |= AS_AREA_READ;
  221.     flags |= AS_AREA_CACHEABLE;
  222.  
  223.     /*
  224.      * Align vaddr down, inserting a little "gap" at the beginning.
  225.      * Adjust area size, so that its end remains in place.
  226.      */
  227.     base = ALIGN_DOWN(entry->p_vaddr, PAGE_SIZE);
  228.     mem_sz = entry->p_memsz + (entry->p_vaddr - base);
  229.  
  230.     a = as_area_create(as, flags, mem_sz, base,
  231.         AS_AREA_ATTR_NONE, &elf_backend, &backend_data);
  232.     if (!a)
  233.         return EE_MEMORY;
  234.    
  235.     /*
  236.      * The segment will be mapped on demand by elf_page_fault().
  237.      */
  238.  
  239.     return EE_OK;
  240. }
  241.  
  242. /** Process section header.
  243.  *
  244.  * @param entry Segment header.
  245.  * @param elf ELF header.
  246.  * @param as Address space into wich the ELF is being loaded.
  247.  *
  248.  * @return EE_OK on success, error code otherwise.
  249.  */
  250. static int section_header(elf_section_header_t *entry, elf_header_t *elf,
  251.     as_t *as)
  252. {
  253.     switch (entry->sh_type) {
  254.     case SHT_PROGBITS:
  255.         if (entry->sh_flags & SHF_TLS) {
  256.             /* .tdata */
  257.         }
  258.         break;
  259.     case SHT_NOBITS:
  260.         if (entry->sh_flags & SHF_TLS) {
  261.             /* .tbss */
  262.         }
  263.         break;
  264.     default:
  265.         break;
  266.     }
  267.    
  268.     return EE_OK;
  269. }
  270.  
  271. /** @}
  272.  */
  273.