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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 <unistd.h>
  46. #include <fcntl.h>
  47.  
  48. #include "elf.h"
  49. #include "pcb.h"
  50. #include "elf_load.h"
  51.  
  52. #define RTLD_BIAS 0x80000
  53. //#define RTLD_BIAS 0
  54.  
  55. static char *error_codes[] = {
  56.     "no error",
  57.     "invalid image",
  58.     "address space error",
  59.     "incompatible image",
  60.     "unsupported image type",
  61.     "irrecoverable error"
  62. };
  63.  
  64. static unsigned int elf_load(elf_ld_t *elf);
  65. static int segment_header(elf_ld_t *elf, elf_segment_header_t *entry);
  66. static int section_header(elf_ld_t *elf, elf_section_header_t *entry);
  67. static int load_segment(elf_ld_t *elf, elf_segment_header_t *entry);
  68.  
  69. int elf_load_file(char *file_name, elf_info_t *info)
  70. {
  71.     elf_ld_t elf;
  72.  
  73.     int fd;
  74.     int rc;
  75.  
  76.     printf("open and read '%s'...\n", file_name);
  77.  
  78.     fd = open(file_name, 0);
  79.     if (fd < 0) {
  80.         printf("failed opening file\n");
  81.         return -1;
  82.     }
  83.  
  84.     elf.fd = fd;
  85.     elf.info = info;
  86.  
  87.     rc = elf_load(&elf);
  88.     printf("elf_load() -> %d\n", rc);
  89.  
  90.     close(fd);
  91.  
  92.     return rc;
  93. }
  94.  
  95. void elf_run(elf_info_t *info)
  96. {
  97.     (*info->entry)();
  98.  
  99.     /* not reached */
  100. }
  101.  
  102. int elf_create_pcb(elf_info_t *info)
  103. {
  104.     pcb_t *pcb;
  105.     void *a;
  106.  
  107.     pcb = (pcb_t *)PCB_ADDRESS;
  108.  
  109.     a = as_area_create(pcb, sizeof(pcb_t), AS_AREA_READ | AS_AREA_WRITE);
  110.     if (a == (void *)(-1)) {
  111.         printf("elf_create_pcb: memory mapping failed\n");
  112.         return EE_MEMORY;
  113.     }
  114.  
  115.     pcb->entry = info->entry;
  116.  
  117.     return 0;
  118. }
  119.  
  120.  
  121. /** ELF loader
  122.  *
  123.  * @param header Pointer to ELF header in memory
  124.  * @return EE_OK on success
  125.  */
  126. static unsigned int elf_load(elf_ld_t *elf)
  127. {
  128.     elf_header_t header_buf;
  129.     elf_header_t *header = &header_buf;
  130.     int i, rc;
  131.  
  132.     rc = read(elf->fd, header, sizeof(elf_header_t));
  133.     if (rc < 0) {
  134.         printf("read error\n");
  135.         return EE_INVALID;
  136.     }
  137.  
  138.     elf->header = header;
  139.  
  140.     printf("ELF-load:");
  141.     /* Identify ELF */
  142.     if (header->e_ident[EI_MAG0] != ELFMAG0 ||
  143.         header->e_ident[EI_MAG1] != ELFMAG1 ||
  144.         header->e_ident[EI_MAG2] != ELFMAG2 ||
  145.         header->e_ident[EI_MAG3] != ELFMAG3) {
  146.         printf("invalid header\n");
  147.         return EE_INVALID;
  148.     }
  149.    
  150.     /* Identify ELF compatibility */
  151.     if (header->e_ident[EI_DATA] != ELF_DATA_ENCODING ||
  152.         header->e_machine != ELF_MACHINE ||
  153.         header->e_ident[EI_VERSION] != EV_CURRENT ||
  154.         header->e_version != EV_CURRENT ||
  155.         header->e_ident[EI_CLASS] != ELF_CLASS) {
  156.         printf("incompatible data/version/class\n");
  157.         return EE_INCOMPATIBLE;
  158.     }
  159.  
  160.     if (header->e_phentsize != sizeof(elf_segment_header_t))
  161.         return EE_INCOMPATIBLE;
  162.  
  163.     if (header->e_shentsize != sizeof(elf_section_header_t))
  164.         return EE_INCOMPATIBLE;
  165.  
  166.     /* Check if the object type is supported. */
  167.     if (header->e_type != ET_EXEC && header->e_type != ET_DYN) {
  168.         printf("Object type %d is not supported\n", header->e_type);
  169.         return EE_UNSUPPORTED;
  170.     }
  171.  
  172.     /* The run-time dynamic linker is loaded with a bias */
  173.     if (header->e_type == ET_DYN)
  174.         elf->bias = RTLD_BIAS;
  175.     else
  176.         elf->bias = 0;
  177.  
  178.     printf("parse segments\n");
  179.  
  180.     /* Walk through all segment headers and process them. */
  181.     for (i = 0; i < header->e_phnum; i++) {
  182.         elf_segment_header_t segment_hdr;
  183.  
  184.         /* Seek to start of segment header */
  185.         lseek(elf->fd, header->e_phoff
  186.                 + i * sizeof(elf_segment_header_t), SEEK_SET);
  187.  
  188.         rc = read(elf->fd, &segment_hdr, sizeof(elf_segment_header_t));
  189.         if (rc < 0) { printf("read error\n"); return EE_INVALID; }
  190.  
  191.         rc = segment_header(elf, &segment_hdr);
  192.         if (rc != EE_OK)
  193.             return rc;
  194.     }
  195.  
  196.     printf("parse sections\n");
  197.  
  198.     /* Inspect all section headers and proccess them. */
  199.     for (i = 0; i < header->e_shnum; i++) {
  200.         elf_section_header_t section_hdr;
  201.  
  202.         /* Seek to start of section header */
  203.         lseek(elf->fd, header->e_shoff
  204.             + i * sizeof(elf_section_header_t), SEEK_SET);
  205.  
  206.         rc = read(elf->fd, &section_hdr, sizeof(elf_section_header_t));
  207.         if (rc < 0) { printf("read error\n"); return EE_INVALID; }
  208.  
  209.         rc = section_header(elf, &section_hdr);
  210.         if (rc != EE_OK)
  211.             return rc;
  212.     }
  213.  
  214.     elf->info->entry =
  215.         (entry_point_t)((uint8_t *)header->e_entry + elf->bias);
  216.  
  217.     printf("done\n");
  218.  
  219.     return EE_OK;
  220. }
  221.  
  222. /** Print error message according to error code.
  223.  *
  224.  * @param rc Return code returned by elf_load().
  225.  *
  226.  * @return NULL terminated description of error.
  227.  */
  228. char *elf_error(unsigned int rc)
  229. {
  230.     assert(rc < sizeof(error_codes) / sizeof(char *));
  231.  
  232.     return error_codes[rc];
  233. }
  234.  
  235. /** Process segment header.
  236.  *
  237.  * @param entry Segment header.
  238.  * @param elf ELF header.
  239.  *
  240.  * @return EE_OK on success, error code otherwise.
  241.  */
  242. static int segment_header(elf_ld_t *elf, elf_segment_header_t *entry)
  243. {
  244.     switch (entry->p_type) {
  245.     case PT_NULL:
  246.     case PT_PHDR:
  247.         break;
  248.     case PT_LOAD:
  249.         return load_segment(elf, entry);
  250.         break;
  251.     case PT_DYNAMIC:
  252.     case PT_INTERP:
  253.     case PT_SHLIB:
  254.     case PT_NOTE:
  255.     case PT_LOPROC:
  256.     case PT_HIPROC:
  257.     default:
  258.         printf("segment p_type %d unknown\n", entry->p_type);
  259.         return EE_UNSUPPORTED;
  260.         break;
  261.     }
  262.     return EE_OK;
  263. }
  264.  
  265. /** Load segment described by program header entry.
  266.  *
  267.  * @param entry Program header entry describing segment to be loaded.
  268.  * @param elf ELF header.
  269.  *
  270.  * @return EE_OK on success, error code otherwise.
  271.  */
  272. int load_segment(elf_ld_t *elf, elf_segment_header_t *entry)
  273. {
  274.     void *a;
  275.     int flags = 0;
  276.     uintptr_t bias;
  277.     int rc;
  278.  
  279.     printf("load segment at addr 0x%x, size 0x%x\n", entry->p_vaddr,
  280.         entry->p_memsz);
  281.    
  282.     bias = elf->bias;
  283.  
  284.     if (entry->p_align > 1) {
  285.         if ((entry->p_offset % entry->p_align) !=
  286.             (entry->p_vaddr % entry->p_align)) {
  287.             printf("align check 1 failed offset%%align=%d, vaddr%%align=%d\n",
  288.             entry->p_offset % entry->p_align,
  289.             entry->p_vaddr % entry->p_align
  290.             );
  291.             return EE_INVALID;
  292.         }
  293.     }
  294.  
  295. /*  if (entry->p_flags & PF_X)
  296.         flags |= AS_AREA_EXEC;
  297.     if (entry->p_flags & PF_W)
  298.         flags |= AS_AREA_WRITE;
  299.     if (entry->p_flags & PF_R)
  300.         flags |= AS_AREA_READ;
  301.     flags |= AS_AREA_CACHEABLE;
  302. */
  303.     /* FIXME: Kernel won't normally allow this, unless you "patch" it */
  304. //  flags = AS_AREA_READ | AS_AREA_WRITE | AS_AREA_EXEC | AS_AREA_CACHEABLE;
  305.     flags = AS_AREA_READ | AS_AREA_WRITE | AS_AREA_CACHEABLE;
  306.  
  307.     /*
  308.      * Check if the virtual address starts on page boundary.
  309.      */
  310.     if (ALIGN_UP(entry->p_vaddr, PAGE_SIZE) != entry->p_vaddr) {
  311.         printf("align check 2 failed - not page-aligned\n");
  312.         printf("vaddr = 0x%x, should be 0x%x\n",
  313.             entry->p_vaddr, ALIGN_UP(entry->p_vaddr, PAGE_SIZE));
  314.         return EE_UNSUPPORTED;
  315.     }
  316.    
  317.     printf("map to p_vaddr=0x%x-0x%x...\n", entry->p_vaddr + bias,
  318.     entry->p_vaddr + bias + ALIGN_UP(entry->p_memsz, PAGE_SIZE));
  319.  
  320.     a = as_area_create((uint8_t *)entry->p_vaddr + bias,
  321.         entry->p_memsz, flags);
  322.     if (a == (void *)(-1)) {
  323.         printf("memory mapping failed\n");
  324.         return EE_MEMORY;
  325.     }
  326.  
  327.     printf("as_area_create(0x%x, 0x%x, %d) -> 0x%x\n",
  328.         entry->p_vaddr+bias, entry->p_memsz, flags, (unsigned)a);
  329.  
  330.     /*
  331.      * Load segment data
  332.      */
  333.     printf("seek to %d\n", entry->p_offset);
  334.     rc = lseek(elf->fd, entry->p_offset, SEEK_SET);
  335.     if (rc < 0) { printf("seek error\n"); return EE_INVALID; }
  336.  
  337.     printf("read 0x%x bytes to address 0x%x\n", entry->p_filesz, entry->p_vaddr+bias);
  338. /*  rc = read(fd, (void *)(entry->p_vaddr + bias), entry->p_filesz);
  339.     if (rc < 0) { printf("read error\n"); return EE_INVALID; }*/
  340.     unsigned left, now;
  341.     uint8_t *dp;
  342.  
  343.     left = entry->p_filesz;
  344.     dp = (uint8_t *)(entry->p_vaddr + bias);
  345.  
  346.     while (left > 0) {
  347.         now = 4096;
  348.         if (now > left) now=left;
  349.         printf("read %d...", now);
  350.         rc = read(elf->fd, dp, now);
  351.         if (rc < 0) { printf("read error\n"); return EE_INVALID; }
  352.         printf("->%d\n", rc);
  353.         left -= now;
  354.         dp += now;
  355.     }
  356.  
  357.     return EE_OK;
  358. }
  359.  
  360. /** Process section header.
  361.  *
  362.  * @param entry Segment header.
  363.  * @param elf ELF header.
  364.  *
  365.  * @return EE_OK on success, error code otherwise.
  366.  */
  367. static int section_header(elf_ld_t *elf, elf_section_header_t *entry)
  368. {
  369.     switch (entry->sh_type) {
  370.     case SHT_PROGBITS:
  371.         if (entry->sh_flags & SHF_TLS) {
  372.             /* .tdata */
  373.         }
  374.         break;
  375.     case SHT_NOBITS:
  376.         if (entry->sh_flags & SHF_TLS) {
  377.             /* .tbss */
  378.         }
  379.         break;
  380.     case SHT_DYNAMIC:
  381.         elf->info->dynamic =
  382.             (void *)((uint8_t *)entry->sh_addr + elf->bias);
  383.         printf("dynamic section found at 0x%x\n",
  384.             (uintptr_t)elf->info->dynamic);
  385.         break;
  386.     default:
  387.         break;
  388.     }
  389.    
  390.     return EE_OK;
  391. }
  392.  
  393. /** @}
  394.  */
  395.