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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. static char *error_codes[] = {
  53.     "no error",
  54.     "invalid image",
  55.     "address space error",
  56.     "incompatible image",
  57.     "unsupported image type",
  58.     "irrecoverable error"
  59. };
  60.  
  61. static unsigned int elf_load(elf_ld_t *elf, size_t so_bias);
  62. static int segment_header(elf_ld_t *elf, elf_segment_header_t *entry);
  63. static int section_header(elf_ld_t *elf, elf_section_header_t *entry);
  64. static int load_segment(elf_ld_t *elf, elf_segment_header_t *entry);
  65.  
  66. int elf_load_file(char *file_name, size_t so_bias, elf_info_t *info)
  67. {
  68.     elf_ld_t elf;
  69.  
  70.     int fd;
  71.     int rc;
  72.  
  73.     printf("open and read '%s'...\n", file_name);
  74.  
  75.     fd = open(file_name, 0);
  76.     if (fd < 0) {
  77.         printf("failed opening file\n");
  78.         return -1;
  79.     }
  80.  
  81.     elf.fd = fd;
  82.     elf.info = info;
  83.  
  84.     rc = elf_load(&elf, so_bias);
  85.     printf("elf_load() -> %d\n", rc);
  86.  
  87.     close(fd);
  88.  
  89.     return rc;
  90. }
  91.  
  92. void elf_run(elf_info_t *info)
  93. {
  94.     (*info->entry)();
  95.  
  96.     /* not reached */
  97. }
  98.  
  99. int elf_create_pcb(elf_info_t *info)
  100. {
  101.     pcb_t *pcb;
  102.     void *a;
  103.  
  104.     pcb = __pcb_get();
  105.  
  106.     a = as_area_create(pcb, sizeof(pcb_t), AS_AREA_READ | AS_AREA_WRITE);
  107.     if (a == (void *)(-1)) {
  108.         printf("elf_create_pcb: memory mapping failed\n");
  109.         return EE_MEMORY;
  110.     }
  111.  
  112.     pcb->entry = info->entry;
  113.     pcb->dynamic = info->dynamic;
  114.  
  115.     return 0;
  116. }
  117.  
  118.  
  119. /** ELF loader
  120.  *
  121.  * @param header Pointer to ELF header in memory
  122.  * @return EE_OK on success
  123.  */
  124. static unsigned int elf_load(elf_ld_t *elf, size_t so_bias)
  125. {
  126.     elf_header_t header_buf;
  127.     elf_header_t *header = &header_buf;
  128.     int i, rc;
  129.  
  130.     rc = read(elf->fd, header, sizeof(elf_header_t));
  131.     if (rc < 0) {
  132.         printf("read error\n");
  133.         return EE_INVALID;
  134.     }
  135.  
  136.     elf->header = header;
  137.  
  138.     printf("ELF-load:");
  139.     /* Identify ELF */
  140.     if (header->e_ident[EI_MAG0] != ELFMAG0 ||
  141.         header->e_ident[EI_MAG1] != ELFMAG1 ||
  142.         header->e_ident[EI_MAG2] != ELFMAG2 ||
  143.         header->e_ident[EI_MAG3] != ELFMAG3) {
  144.         printf("invalid header\n");
  145.         return EE_INVALID;
  146.     }
  147.    
  148.     /* Identify ELF compatibility */
  149.     if (header->e_ident[EI_DATA] != ELF_DATA_ENCODING ||
  150.         header->e_machine != ELF_MACHINE ||
  151.         header->e_ident[EI_VERSION] != EV_CURRENT ||
  152.         header->e_version != EV_CURRENT ||
  153.         header->e_ident[EI_CLASS] != ELF_CLASS) {
  154.         printf("incompatible data/version/class\n");
  155.         return EE_INCOMPATIBLE;
  156.     }
  157.  
  158.     if (header->e_phentsize != sizeof(elf_segment_header_t)) {
  159.         printf("e_phentsize:%d != %d\n", header->e_phentsize,
  160.             sizeof(elf_segment_header_t));
  161.         return EE_INCOMPATIBLE;
  162.     }
  163.  
  164.     if (header->e_shentsize != sizeof(elf_section_header_t)) {
  165.         printf("e_shentsize:%d != %d\n", header->e_shentsize,
  166.             sizeof(elf_section_header_t));
  167.         return EE_INCOMPATIBLE;
  168.     }
  169.  
  170.     /* Check if the object type is supported. */
  171.     if (header->e_type != ET_EXEC && header->e_type != ET_DYN) {
  172.         printf("Object type %d is not supported\n", header->e_type);
  173.         return EE_UNSUPPORTED;
  174.     }
  175.  
  176.     /* Shared objects can be loaded with a bias */
  177.     printf("Object type: %d\n", header->e_type);
  178.     if (header->e_type == ET_DYN)
  179.         elf->bias = so_bias;
  180.     else
  181.         elf->bias = 0;
  182.  
  183.     printf("Bias set to 0x%x\n", elf->bias);
  184.  
  185.     printf("parse segments\n");
  186.  
  187.     /* Walk through all segment headers and process them. */
  188.     for (i = 0; i < header->e_phnum; i++) {
  189.         elf_segment_header_t segment_hdr;
  190.  
  191.         /* Seek to start of segment header */
  192.         lseek(elf->fd, header->e_phoff
  193.                 + i * sizeof(elf_segment_header_t), SEEK_SET);
  194.  
  195.         rc = read(elf->fd, &segment_hdr, sizeof(elf_segment_header_t));
  196.         if (rc < 0) { printf("read error\n"); return EE_INVALID; }
  197.  
  198.         rc = segment_header(elf, &segment_hdr);
  199.         if (rc != EE_OK)
  200.             return rc;
  201.     }
  202.  
  203.     printf("parse sections\n");
  204.  
  205.     /* Inspect all section headers and proccess them. */
  206.     for (i = 0; i < header->e_shnum; i++) {
  207.         elf_section_header_t section_hdr;
  208.  
  209.         /* Seek to start of section header */
  210.         lseek(elf->fd, header->e_shoff
  211.             + i * sizeof(elf_section_header_t), SEEK_SET);
  212.  
  213.         rc = read(elf->fd, &section_hdr, sizeof(elf_section_header_t));
  214.         if (rc < 0) { printf("read error\n"); return EE_INVALID; }
  215.  
  216.         rc = section_header(elf, &section_hdr);
  217.         if (rc != EE_OK)
  218.             return rc;
  219.     }
  220.  
  221.     elf->info->entry =
  222.         (entry_point_t)((uint8_t *)header->e_entry + elf->bias);
  223.  
  224.     printf("done\n");
  225.  
  226.     return EE_OK;
  227. }
  228.  
  229. /** Print error message according to error code.
  230.  *
  231.  * @param rc Return code returned by elf_load().
  232.  *
  233.  * @return NULL terminated description of error.
  234.  */
  235. char *elf_error(unsigned int rc)
  236. {
  237.     assert(rc < sizeof(error_codes) / sizeof(char *));
  238.  
  239.     return error_codes[rc];
  240. }
  241.  
  242. /** Process segment header.
  243.  *
  244.  * @param entry Segment header.
  245.  * @param elf ELF header.
  246.  *
  247.  * @return EE_OK on success, error code otherwise.
  248.  */
  249. static int segment_header(elf_ld_t *elf, elf_segment_header_t *entry)
  250. {
  251.     switch (entry->p_type) {
  252.     case PT_NULL:
  253.     case PT_PHDR:
  254.         break;
  255.     case PT_LOAD:
  256.         return load_segment(elf, entry);
  257.         break;
  258.     case PT_DYNAMIC:
  259.     case PT_INTERP:
  260.     case PT_SHLIB:
  261.     case PT_NOTE:
  262.     case PT_LOPROC:
  263.     case PT_HIPROC:
  264.     default:
  265.         printf("segment p_type %d unknown\n", entry->p_type);
  266.         return EE_UNSUPPORTED;
  267.         break;
  268.     }
  269.     return EE_OK;
  270. }
  271.  
  272. /** Load segment described by program header entry.
  273.  *
  274.  * @param entry Program header entry describing segment to be loaded.
  275.  * @param elf ELF header.
  276.  *
  277.  * @return EE_OK on success, error code otherwise.
  278.  */
  279. int load_segment(elf_ld_t *elf, elf_segment_header_t *entry)
  280. {
  281.     void *a;
  282.     int flags = 0;
  283.     uintptr_t bias;
  284.     int rc;
  285.  
  286.     printf("load segment at addr 0x%x, size 0x%x\n", entry->p_vaddr,
  287.         entry->p_memsz);
  288.    
  289.     bias = elf->bias;
  290.  
  291.     if (entry->p_align > 1) {
  292.         if ((entry->p_offset % entry->p_align) !=
  293.             (entry->p_vaddr % entry->p_align)) {
  294.             printf("align check 1 failed offset%%align=%d, vaddr%%align=%d\n",
  295.             entry->p_offset % entry->p_align,
  296.             entry->p_vaddr % entry->p_align
  297.             );
  298.             return EE_INVALID;
  299.         }
  300.     }
  301.  
  302.     /* Final flags that will be set for the memory area */
  303.  
  304.     if (entry->p_flags & PF_X)
  305.         flags |= AS_AREA_EXEC;
  306.     if (entry->p_flags & PF_W)
  307.         flags |= AS_AREA_WRITE;
  308.     if (entry->p_flags & PF_R)
  309.         flags |= AS_AREA_READ;
  310.     flags |= AS_AREA_CACHEABLE;
  311.  
  312.     /*
  313.      * Check if the virtual address starts on page boundary.
  314.      */
  315.     if (ALIGN_UP(entry->p_vaddr, PAGE_SIZE) != entry->p_vaddr) {
  316.         printf("align check 2 failed - not page-aligned\n");
  317.         printf("vaddr = 0x%x, should be 0x%x\n",
  318.             entry->p_vaddr, ALIGN_UP(entry->p_vaddr, PAGE_SIZE));
  319.         return EE_UNSUPPORTED;
  320.     }
  321.    
  322.     printf("map to p_vaddr=0x%x-0x%x...\n", entry->p_vaddr + bias,
  323.     entry->p_vaddr + bias + ALIGN_UP(entry->p_memsz, PAGE_SIZE));
  324.  
  325.     /*
  326.      * For the course of loading, the area needs to be readable
  327.      * and writeable.
  328.      */
  329.     a = as_area_create((uint8_t *)entry->p_vaddr + bias,
  330.         entry->p_memsz, AS_AREA_READ | AS_AREA_WRITE | AS_AREA_CACHEABLE);
  331.     if (a == (void *)(-1)) {
  332.         printf("memory mapping failed\n");
  333.         return EE_MEMORY;
  334.     }
  335.  
  336.     printf("as_area_create(0x%lx, 0x%x, %d) -> 0x%lx\n",
  337.         entry->p_vaddr+bias, entry->p_memsz, flags, (uintptr_t)a);
  338.  
  339.     /*
  340.      * Load segment data
  341.      */
  342.     printf("seek to %d\n", entry->p_offset);
  343.     rc = lseek(elf->fd, entry->p_offset, SEEK_SET);
  344.     if (rc < 0) { printf("seek error\n"); return EE_INVALID; }
  345.  
  346.     printf("read 0x%x bytes to address 0x%x\n", entry->p_filesz, entry->p_vaddr+bias);
  347. /*  rc = read(fd, (void *)(entry->p_vaddr + bias), entry->p_filesz);
  348.     if (rc < 0) { printf("read error\n"); return EE_INVALID; }*/
  349.     unsigned left, now;
  350.     uint8_t *dp;
  351.  
  352.     left = entry->p_filesz;
  353.     dp = (uint8_t *)(entry->p_vaddr + bias);
  354.  
  355.     while (left > 0) {
  356.         now = 16384;
  357.         if (now > left) now=left;
  358.         printf("read %d...", now);
  359.         rc = read(elf->fd, dp, now);
  360.         if (rc < 0) { printf("read error\n"); return EE_INVALID; }
  361.         printf("->%d\n", rc);
  362.         left -= now;
  363.         dp += now;
  364.     }
  365.  
  366.     printf("set area flags to %d\n", flags);
  367.     rc = as_area_change_flags((uint8_t *)entry->p_vaddr + bias, flags);
  368.     if (rc != 0) {
  369.         printf("failed to set memory area flags\n");
  370.         return EE_MEMORY;
  371.     }
  372.  
  373.     return EE_OK;
  374. }
  375.  
  376. /** Process section header.
  377.  *
  378.  * @param entry Segment header.
  379.  * @param elf ELF header.
  380.  *
  381.  * @return EE_OK on success, error code otherwise.
  382.  */
  383. static int section_header(elf_ld_t *elf, elf_section_header_t *entry)
  384. {
  385.     switch (entry->sh_type) {
  386.     case SHT_PROGBITS:
  387.         if (entry->sh_flags & SHF_TLS) {
  388.             /* .tdata */
  389.         }
  390.         break;
  391.     case SHT_NOBITS:
  392.         if (entry->sh_flags & SHF_TLS) {
  393.             /* .tbss */
  394.         }
  395.         break;
  396.     case SHT_DYNAMIC:
  397.         elf->info->dynamic =
  398.             (void *)((uint8_t *)entry->sh_addr + elf->bias);
  399.         printf("dynamic section found at 0x%x\n",
  400.             (uintptr_t)elf->info->dynamic);
  401.         break;
  402.     default:
  403.         break;
  404.     }
  405.    
  406.     return EE_OK;
  407. }
  408.  
  409. /** @}
  410.  */
  411.