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  1. /*
  2.  * Copyright (c) 2006 Sergey Bondari
  3.  * Copyright (c) 2006 Jakub Jermar
  4.  * Copyright (c) 2008 Jiri Svoboda
  5.  * All rights reserved.
  6.  *
  7.  * Redistribution and use in source and binary forms, with or without
  8.  * modification, are permitted provided that the following conditions
  9.  * are met:
  10.  *
  11.  * - Redistributions of source code must retain the above copyright
  12.  *   notice, this list of conditions and the following disclaimer.
  13.  * - Redistributions in binary form must reproduce the above copyright
  14.  *   notice, this list of conditions and the following disclaimer in the
  15.  *   documentation and/or other materials provided with the distribution.
  16.  * - The name of the author may not be used to endorse or promote products
  17.  *   derived from this software without specific prior written permission.
  18.  *
  19.  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
  20.  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
  21.  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
  22.  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
  23.  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
  24.  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  25.  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  26.  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  27.  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
  28.  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  29.  */
  30.  
  31. /** @addtogroup generic
  32.  * @{
  33.  */
  34.  
  35. /**
  36.  * @file
  37.  * @brief   Kernel ELF loader.
  38.  */
  39.  
  40. #include <stdio.h>
  41. #include <sys/types.h>
  42. #include <align.h>
  43. #include <assert.h>
  44. #include <as.h>
  45. #include "elf.h"
  46.  
  47. #define RTLD_BIAS 0x80000
  48.  
  49. static char *error_codes[] = {
  50.     "no error",
  51.     "invalid image",
  52.     "address space error",
  53.     "incompatible image",
  54.     "unsupported image type",
  55.     "irrecoverable error"
  56. };
  57.  
  58. static int segment_header(int fd, elf_header_t *elf);
  59. static int section_header(elf_section_header_t *entry, elf_header_t *elf);
  60. static int load_segment(int fd, elf_segment_header_t *entry, elf_header_t *elf);
  61.  
  62. typedef void (*epoint_t)(void);
  63.  
  64. /** ELF loader
  65.  *
  66.  * @param header Pointer to ELF header in memory
  67.  * @return EE_OK on success
  68.  */
  69. unsigned int elf_load(int fd, elf_header_t *header)
  70. {
  71.     int i, rc;
  72.  
  73.     rc = read(fd, header, sizeof(elf_header_t));
  74.     if (rc < 0) {
  75.         printf("read error\n");
  76.         return EE_INVALID;
  77.     }
  78.  
  79.     printf("ELF-load:");
  80.     /* Identify ELF */
  81.     if (header->e_ident[EI_MAG0] != ELFMAG0 ||
  82.         header->e_ident[EI_MAG1] != ELFMAG1 ||
  83.         header->e_ident[EI_MAG2] != ELFMAG2 ||
  84.         header->e_ident[EI_MAG3] != ELFMAG3) {
  85.         printf("invalid header\n");
  86.         return EE_INVALID;
  87.     }
  88.    
  89.     /* Identify ELF compatibility */
  90.     if (header->e_ident[EI_DATA] != ELF_DATA_ENCODING ||
  91.         header->e_machine != ELF_MACHINE ||
  92.         header->e_ident[EI_VERSION] != EV_CURRENT ||
  93.         header->e_version != EV_CURRENT ||
  94.         header->e_ident[EI_CLASS] != ELF_CLASS) {
  95.         printf("incompatible data/version/class\n");
  96.         return EE_INCOMPATIBLE;
  97.     }
  98.  
  99.     if (header->e_phentsize != sizeof(elf_segment_header_t))
  100.         return EE_INCOMPATIBLE;
  101.  
  102.     if (header->e_shentsize != sizeof(elf_section_header_t))
  103.         return EE_INCOMPATIBLE;
  104.  
  105.     /* Check if the object type is supported. */
  106.     if (header->e_type != ET_EXEC && header->e_type != ET_DYN) {
  107.         printf("Object type %d is not supported\n", header->e_type);
  108.         return EE_UNSUPPORTED;
  109.     }
  110.     if (header->e_type == ET_DYN) header->e_entry += RTLD_BIAS;
  111.  
  112.     printf("parse segments\n");
  113.  
  114.     /* Walk through all segment headers and process them. */
  115.     for (i = 0; i < header->e_phnum; i++) {
  116.  
  117.         /* Seek to start of header */
  118.         lseek(fd, header->e_phoff + i * sizeof(elf_segment_header_t), SEEK_SET);
  119.  
  120.         rc = segment_header(fd, header);
  121.         if (rc != EE_OK)
  122.             return rc;
  123.     }
  124.  
  125.     printf("parse sections\n");
  126.  
  127.     /* Inspect all section headers and proccess them. */
  128.     for (i = 0; i < header->e_shnum; i++) {
  129. /*      elf_section_header_t *sechdr;
  130.  
  131.         sechdr = &((elf_section_header_t *)(((uint8_t *) header) +
  132.             header->e_shoff))[i];
  133.         rc = section_header(sechdr, header);
  134.         if (rc != EE_OK)
  135.             return rc;*/
  136.     }
  137.  
  138.     printf("done\n");
  139.  
  140.     return EE_OK;
  141. }
  142.  
  143. /** Print error message according to error code.
  144.  *
  145.  * @param rc Return code returned by elf_load().
  146.  *
  147.  * @return NULL terminated description of error.
  148.  */
  149. char *elf_error(unsigned int rc)
  150. {
  151.     assert(rc < sizeof(error_codes) / sizeof(char *));
  152.  
  153.     return error_codes[rc];
  154. }
  155.  
  156. /** Process segment header.
  157.  *
  158.  * @param entry Segment header.
  159.  * @param elf ELF header.
  160.  *
  161.  * @return EE_OK on success, error code otherwise.
  162.  */
  163. static int segment_header(int fd, elf_header_t *elf)
  164. {
  165.     static elf_segment_header_t entry_buf;
  166.     elf_segment_header_t *entry = &entry_buf;
  167.     int rc;
  168.  
  169.     rc = read(fd, entry, sizeof(elf_segment_header_t));
  170.     if (rc < 0) { printf("read error\n"); return EE_INVALID; }
  171.  
  172.     switch (entry->p_type) {
  173.     case PT_NULL:
  174.     case PT_PHDR:
  175.         break;
  176.     case PT_LOAD:
  177.         return load_segment(fd, entry, elf);
  178.         break;
  179.     case PT_DYNAMIC:
  180.     case PT_INTERP:
  181.     case PT_SHLIB:
  182.     case PT_NOTE:
  183.     case PT_LOPROC:
  184.     case PT_HIPROC:
  185.     default:
  186.         printf("segment p_type %d unknown\n", entry->p_type);
  187.         return EE_UNSUPPORTED;
  188.         break;
  189.     }
  190.     return EE_OK;
  191. }
  192.  
  193. /** Load segment described by program header entry.
  194.  *
  195.  * @param entry Program header entry describing segment to be loaded.
  196.  * @param elf ELF header.
  197.  *
  198.  * @return EE_OK on success, error code otherwise.
  199.  */
  200. int load_segment(int fd, elf_segment_header_t *entry, elf_header_t *elf)
  201. {
  202.     void *a;
  203.     int flags = 0;
  204.     uintptr_t bias;
  205.     int rc;
  206.  
  207.     printf("load segment at addr 0x%x, size 0x%x\n", entry->p_vaddr,
  208.         entry->p_memsz);
  209.    
  210.     bias = (elf->e_type == ET_DYN) ? RTLD_BIAS : 0;
  211.  
  212.     if (entry->p_align > 1) {
  213.         if ((entry->p_offset % entry->p_align) !=
  214.             (entry->p_vaddr % entry->p_align)) {
  215.             printf("align check 1 failed offset%%align=%d, vaddr%%align=%d\n",
  216.             entry->p_offset % entry->p_align,
  217.             entry->p_vaddr % entry->p_align
  218.             );
  219.             return EE_INVALID;
  220.         }
  221.     }
  222.  
  223. /*  if (entry->p_flags & PF_X)
  224.         flags |= AS_AREA_EXEC;
  225.     if (entry->p_flags & PF_W)
  226.         flags |= AS_AREA_WRITE;
  227.     if (entry->p_flags & PF_R)
  228.         flags |= AS_AREA_READ;
  229.     flags |= AS_AREA_CACHEABLE;
  230. */
  231.     /* FIXME: Kernel won't normally allow this, unless you "patch" it */
  232.     flags = AS_AREA_READ | AS_AREA_WRITE | AS_AREA_EXEC | AS_AREA_CACHEABLE;
  233.  
  234.     /*
  235.      * Check if the virtual address starts on page boundary.
  236.      */
  237.     if (ALIGN_UP(entry->p_vaddr, PAGE_SIZE) != entry->p_vaddr) {
  238.         printf("align check 2 failed - not page-aligned\n");
  239.         printf("vaddr = 0x%x, should be 0x%x\n",
  240.             entry->p_vaddr, ALIGN_UP(entry->p_vaddr, PAGE_SIZE));
  241.         return EE_UNSUPPORTED;
  242.     }
  243.    
  244.     printf("map to p_vaddr=0x%x-0x%x...\n", entry->p_vaddr + bias,
  245.     entry->p_vaddr + bias + ALIGN_UP(entry->p_memsz, PAGE_SIZE));
  246.  
  247.     a = as_area_create((uint8_t *)entry->p_vaddr + bias,
  248.         entry->p_memsz, flags);
  249.     if (a == (void *)(-1)) {
  250.         printf("memory mapping failed\n");
  251.         return EE_MEMORY;
  252.     }
  253.  
  254.     printf("as_area_create() -> 0x%x\n", (unsigned)a);
  255.  
  256.     /*
  257.      * Load segment data
  258.      */
  259.     rc = lseek(fd, entry->p_offset, SEEK_SET);
  260.     if (rc < 0) { printf("seek error\n"); return EE_INVALID; }
  261.  
  262.     rc = read(fd, (void *)(entry->p_vaddr + bias), entry->p_filesz);
  263.     if (rc < 0) { printf("read error\n"); return EE_INVALID; }
  264.  
  265.     return EE_OK;
  266. }
  267.  
  268. /** Process section header.
  269.  *
  270.  * @param entry Segment header.
  271.  * @param elf ELF header.
  272.  *
  273.  * @return EE_OK on success, error code otherwise.
  274.  */
  275. static int section_header(elf_section_header_t *entry, elf_header_t *elf)
  276. {
  277.     switch (entry->sh_type) {
  278.     case SHT_PROGBITS:
  279.         if (entry->sh_flags & SHF_TLS) {
  280.             /* .tdata */
  281.         }
  282.         break;
  283.     case SHT_NOBITS:
  284.         if (entry->sh_flags & SHF_TLS) {
  285.             /* .tbss */
  286.         }
  287.         break;
  288.     default:
  289.         break;
  290.     }
  291.    
  292.     return EE_OK;
  293. }
  294.  
  295. /** @}
  296.  */
  297.