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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. //#define RTLD_BIAS 0
  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(int fd, elf_header_t *elf);
  60. static int section_header(elf_section_header_t *entry, elf_header_t *elf);
  61. static int load_segment(int fd, elf_segment_header_t *entry, elf_header_t *elf);
  62.  
  63. typedef void (*epoint_t)(void);
  64.  
  65. /** ELF loader
  66.  *
  67.  * @param header Pointer to ELF header in memory
  68.  * @return EE_OK on success
  69.  */
  70. unsigned int elf_load(int fd, elf_header_t *header)
  71. {
  72.     int i, rc;
  73.  
  74.     rc = read(fd, header, sizeof(elf_header_t));
  75.     if (rc < 0) {
  76.         printf("read error\n");
  77.         return EE_INVALID;
  78.     }
  79.  
  80.     printf("ELF-load:");
  81.     /* Identify ELF */
  82.     if (header->e_ident[EI_MAG0] != ELFMAG0 ||
  83.         header->e_ident[EI_MAG1] != ELFMAG1 ||
  84.         header->e_ident[EI_MAG2] != ELFMAG2 ||
  85.         header->e_ident[EI_MAG3] != ELFMAG3) {
  86.         printf("invalid header\n");
  87.         return EE_INVALID;
  88.     }
  89.    
  90.     /* Identify ELF compatibility */
  91.     if (header->e_ident[EI_DATA] != ELF_DATA_ENCODING ||
  92.         header->e_machine != ELF_MACHINE ||
  93.         header->e_ident[EI_VERSION] != EV_CURRENT ||
  94.         header->e_version != EV_CURRENT ||
  95.         header->e_ident[EI_CLASS] != ELF_CLASS) {
  96.         printf("incompatible data/version/class\n");
  97.         return EE_INCOMPATIBLE;
  98.     }
  99.  
  100.     if (header->e_phentsize != sizeof(elf_segment_header_t))
  101.         return EE_INCOMPATIBLE;
  102.  
  103.     if (header->e_shentsize != sizeof(elf_section_header_t))
  104.         return EE_INCOMPATIBLE;
  105.  
  106.     /* Check if the object type is supported. */
  107.     if (header->e_type != ET_EXEC && header->e_type != ET_DYN) {
  108.         printf("Object type %d is not supported\n", header->e_type);
  109.         return EE_UNSUPPORTED;
  110.     }
  111.     if (header->e_type == ET_DYN) header->e_entry += RTLD_BIAS;
  112.  
  113.     printf("parse segments\n");
  114.  
  115.     /* Walk through all segment headers and process them. */
  116.     for (i = 0; i < header->e_phnum; i++) {
  117.  
  118.         /* Seek to start of header */
  119.         lseek(fd, header->e_phoff + i * sizeof(elf_segment_header_t), SEEK_SET);
  120.  
  121.         rc = segment_header(fd, header);
  122.         if (rc != EE_OK)
  123.             return rc;
  124.     }
  125.  
  126.     printf("parse sections\n");
  127.  
  128.     /* Inspect all section headers and proccess them. */
  129.     for (i = 0; i < header->e_shnum; i++) {
  130. /*      elf_section_header_t *sechdr;
  131.  
  132.         sechdr = &((elf_section_header_t *)(((uint8_t *) header) +
  133.             header->e_shoff))[i];
  134.         rc = section_header(sechdr, header);
  135.         if (rc != EE_OK)
  136.             return rc;*/
  137.     }
  138.  
  139.     printf("done\n");
  140.  
  141.     return EE_OK;
  142. }
  143.  
  144. /** Print error message according to error code.
  145.  *
  146.  * @param rc Return code returned by elf_load().
  147.  *
  148.  * @return NULL terminated description of error.
  149.  */
  150. char *elf_error(unsigned int rc)
  151. {
  152.     assert(rc < sizeof(error_codes) / sizeof(char *));
  153.  
  154.     return error_codes[rc];
  155. }
  156.  
  157. /** Process segment header.
  158.  *
  159.  * @param entry Segment header.
  160.  * @param elf ELF header.
  161.  *
  162.  * @return EE_OK on success, error code otherwise.
  163.  */
  164. static int segment_header(int fd, elf_header_t *elf)
  165. {
  166.     static elf_segment_header_t entry_buf;
  167.     elf_segment_header_t *entry = &entry_buf;
  168.     int rc;
  169.  
  170.     rc = read(fd, entry, sizeof(elf_segment_header_t));
  171.     if (rc < 0) { printf("read error\n"); return EE_INVALID; }
  172.  
  173.     switch (entry->p_type) {
  174.     case PT_NULL:
  175.     case PT_PHDR:
  176.         break;
  177.     case PT_LOAD:
  178.         return load_segment(fd, entry, elf);
  179.         break;
  180.     case PT_DYNAMIC:
  181.     case PT_INTERP:
  182.     case PT_SHLIB:
  183.     case PT_NOTE:
  184.     case PT_LOPROC:
  185.     case PT_HIPROC:
  186.     default:
  187.         printf("segment p_type %d unknown\n", entry->p_type);
  188.         return EE_UNSUPPORTED;
  189.         break;
  190.     }
  191.     return EE_OK;
  192. }
  193.  
  194. /** Load segment described by program header entry.
  195.  *
  196.  * @param entry Program header entry describing segment to be loaded.
  197.  * @param elf ELF header.
  198.  *
  199.  * @return EE_OK on success, error code otherwise.
  200.  */
  201. int load_segment(int fd, elf_segment_header_t *entry, elf_header_t *elf)
  202. {
  203.     void *a;
  204.     int flags = 0;
  205.     uintptr_t bias;
  206.     int rc;
  207.  
  208.     printf("load segment at addr 0x%x, size 0x%x\n", entry->p_vaddr,
  209.         entry->p_memsz);
  210.    
  211.     bias = (elf->e_type == ET_DYN) ? RTLD_BIAS : 0;
  212.  
  213.     if (entry->p_align > 1) {
  214.         if ((entry->p_offset % entry->p_align) !=
  215.             (entry->p_vaddr % entry->p_align)) {
  216.             printf("align check 1 failed offset%%align=%d, vaddr%%align=%d\n",
  217.             entry->p_offset % entry->p_align,
  218.             entry->p_vaddr % entry->p_align
  219.             );
  220.             return EE_INVALID;
  221.         }
  222.     }
  223.  
  224. /*  if (entry->p_flags & PF_X)
  225.         flags |= AS_AREA_EXEC;
  226.     if (entry->p_flags & PF_W)
  227.         flags |= AS_AREA_WRITE;
  228.     if (entry->p_flags & PF_R)
  229.         flags |= AS_AREA_READ;
  230.     flags |= AS_AREA_CACHEABLE;
  231. */
  232.     /* FIXME: Kernel won't normally allow this, unless you "patch" it */
  233. //  flags = AS_AREA_READ | AS_AREA_WRITE | AS_AREA_EXEC | AS_AREA_CACHEABLE;
  234.     flags = AS_AREA_READ | AS_AREA_WRITE | AS_AREA_CACHEABLE;
  235.  
  236.     /*
  237.      * Check if the virtual address starts on page boundary.
  238.      */
  239.     if (ALIGN_UP(entry->p_vaddr, PAGE_SIZE) != entry->p_vaddr) {
  240.         printf("align check 2 failed - not page-aligned\n");
  241.         printf("vaddr = 0x%x, should be 0x%x\n",
  242.             entry->p_vaddr, ALIGN_UP(entry->p_vaddr, PAGE_SIZE));
  243.         return EE_UNSUPPORTED;
  244.     }
  245.    
  246.     printf("map to p_vaddr=0x%x-0x%x...\n", entry->p_vaddr + bias,
  247.     entry->p_vaddr + bias + ALIGN_UP(entry->p_memsz, PAGE_SIZE));
  248.  
  249.     a = as_area_create((uint8_t *)entry->p_vaddr + bias,
  250.         entry->p_memsz, flags);
  251.     if (a == (void *)(-1)) {
  252.         printf("memory mapping failed\n");
  253.         return EE_MEMORY;
  254.     }
  255.  
  256.     printf("as_area_create(0x%x, 0x%x, %d) -> 0x%x\n",
  257.         entry->p_vaddr+bias, entry->p_memsz, flags, (unsigned)a);
  258.  
  259.     /*
  260.      * Load segment data
  261.      */
  262.     printf("seek to %d\n", entry->p_offset);
  263.     rc = lseek(fd, entry->p_offset, SEEK_SET);
  264.     if (rc < 0) { printf("seek error\n"); return EE_INVALID; }
  265.  
  266.     printf("read 0x%x bytes to address 0x%x\n", entry->p_filesz, entry->p_vaddr+bias);
  267. /*  rc = read(fd, (void *)(entry->p_vaddr + bias), entry->p_filesz);
  268.     if (rc < 0) { printf("read error\n"); return EE_INVALID; }*/
  269.     unsigned left, now;
  270.     uint8_t *dp;
  271.  
  272.     left = entry->p_filesz;
  273.     dp = (uint8_t *)(entry->p_vaddr + bias);
  274.  
  275.     while (left > 0) {
  276.         now = 4096;
  277.         if (now > left) now=left;
  278.         printf("read %d...", now);
  279.         rc = read(fd, dp, now);
  280.         if (rc < 0) { printf("read error\n"); return EE_INVALID; }
  281.         printf("->%d\n", rc);
  282.         left -= now;
  283.         dp += now;
  284.     }
  285.  
  286.     return EE_OK;
  287. }
  288.  
  289. /** Process section header.
  290.  *
  291.  * @param entry Segment header.
  292.  * @param elf ELF header.
  293.  *
  294.  * @return EE_OK on success, error code otherwise.
  295.  */
  296. static int section_header(elf_section_header_t *entry, elf_header_t *elf)
  297. {
  298.     switch (entry->sh_type) {
  299.     case SHT_PROGBITS:
  300.         if (entry->sh_flags & SHF_TLS) {
  301.             /* .tdata */
  302.         }
  303.         break;
  304.     case SHT_NOBITS:
  305.         if (entry->sh_flags & SHF_TLS) {
  306.             /* .tbss */
  307.         }
  308.         break;
  309.     default:
  310.         break;
  311.     }
  312.    
  313.     return EE_OK;
  314. }
  315.  
  316. /** @}
  317.  */
  318.