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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(int fd, elf_header_t *header);
  65. static int segment_header(int fd, elf_header_t *elf);
  66. static int section_header(int fd, elf_header_t *elf);
  67. static int load_segment(int fd, elf_segment_header_t *entry, elf_header_t *elf);
  68.  
  69. typedef void (*entry_point_t)(void);
  70.  
  71. int elf_load_file(char *file_name, elf_header_t *header)
  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.     rc = elf_load(fd, header);
  85.     printf("elf_load() -> %d\n", rc);
  86.  
  87.     close(fd);
  88.  
  89.     return rc;
  90. }
  91.  
  92. void elf_run(elf_header_t *header)
  93. {
  94.     entry_point_t entry_point;
  95.  
  96.     entry_point = (entry_point_t)header->e_entry;
  97.     (*entry_point)();
  98.  
  99.     /* not reached */
  100. }
  101.  
  102. int elf_create_pcb(elf_header_t *header)
  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 = (entry_point_t)header->e_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(int fd, elf_header_t *header)
  127. {
  128.     int i, rc;
  129.  
  130.     rc = read(fd, header, sizeof(elf_header_t));
  131.     if (rc < 0) {
  132.         printf("read error\n");
  133.         return EE_INVALID;
  134.     }
  135.  
  136.     printf("ELF-load:");
  137.     /* Identify ELF */
  138.     if (header->e_ident[EI_MAG0] != ELFMAG0 ||
  139.         header->e_ident[EI_MAG1] != ELFMAG1 ||
  140.         header->e_ident[EI_MAG2] != ELFMAG2 ||
  141.         header->e_ident[EI_MAG3] != ELFMAG3) {
  142.         printf("invalid header\n");
  143.         return EE_INVALID;
  144.     }
  145.    
  146.     /* Identify ELF compatibility */
  147.     if (header->e_ident[EI_DATA] != ELF_DATA_ENCODING ||
  148.         header->e_machine != ELF_MACHINE ||
  149.         header->e_ident[EI_VERSION] != EV_CURRENT ||
  150.         header->e_version != EV_CURRENT ||
  151.         header->e_ident[EI_CLASS] != ELF_CLASS) {
  152.         printf("incompatible data/version/class\n");
  153.         return EE_INCOMPATIBLE;
  154.     }
  155.  
  156.     if (header->e_phentsize != sizeof(elf_segment_header_t))
  157.         return EE_INCOMPATIBLE;
  158.  
  159.     if (header->e_shentsize != sizeof(elf_section_header_t))
  160.         return EE_INCOMPATIBLE;
  161.  
  162.     /* Check if the object type is supported. */
  163.     if (header->e_type != ET_EXEC && header->e_type != ET_DYN) {
  164.         printf("Object type %d is not supported\n", header->e_type);
  165.         return EE_UNSUPPORTED;
  166.     }
  167.     if (header->e_type == ET_DYN) header->e_entry += RTLD_BIAS;
  168.  
  169.     printf("parse segments\n");
  170.  
  171.     /* Walk through all segment headers and process them. */
  172.     for (i = 0; i < header->e_phnum; i++) {
  173.  
  174.         /* Seek to start of segment header */
  175.         lseek(fd, header->e_phoff + i * sizeof(elf_segment_header_t),
  176.             SEEK_SET);
  177.  
  178.         rc = segment_header(fd, header);
  179.         if (rc != EE_OK)
  180.             return rc;
  181.     }
  182.  
  183.     printf("parse sections\n");
  184.  
  185.     /* Inspect all section headers and proccess them. */
  186.     for (i = 0; i < header->e_shnum; i++) {
  187.  
  188.         /* Seek to start of section header */
  189.         lseek(fd, header->e_shoff + i * sizeof(elf_section_header_t),
  190.             SEEK_SET);
  191.  
  192.         rc = section_header(fd, header);
  193.         if (rc != EE_OK)
  194.             return rc;
  195.     }
  196.  
  197.     printf("done\n");
  198.  
  199.     return EE_OK;
  200. }
  201.  
  202. /** Print error message according to error code.
  203.  *
  204.  * @param rc Return code returned by elf_load().
  205.  *
  206.  * @return NULL terminated description of error.
  207.  */
  208. char *elf_error(unsigned int rc)
  209. {
  210.     assert(rc < sizeof(error_codes) / sizeof(char *));
  211.  
  212.     return error_codes[rc];
  213. }
  214.  
  215. /** Process segment header.
  216.  *
  217.  * @param entry Segment header.
  218.  * @param elf ELF header.
  219.  *
  220.  * @return EE_OK on success, error code otherwise.
  221.  */
  222. static int segment_header(int fd, elf_header_t *elf)
  223. {
  224.     static elf_segment_header_t entry_buf;
  225.     elf_segment_header_t *entry = &entry_buf;
  226.     int rc;
  227.  
  228.     rc = read(fd, entry, sizeof(elf_segment_header_t));
  229.     if (rc < 0) { printf("read error\n"); return EE_INVALID; }
  230.  
  231.     switch (entry->p_type) {
  232.     case PT_NULL:
  233.     case PT_PHDR:
  234.         break;
  235.     case PT_LOAD:
  236.         return load_segment(fd, entry, elf);
  237.         break;
  238.     case PT_DYNAMIC:
  239.     case PT_INTERP:
  240.     case PT_SHLIB:
  241.     case PT_NOTE:
  242.     case PT_LOPROC:
  243.     case PT_HIPROC:
  244.     default:
  245.         printf("segment p_type %d unknown\n", entry->p_type);
  246.         return EE_UNSUPPORTED;
  247.         break;
  248.     }
  249.     return EE_OK;
  250. }
  251.  
  252. /** Load segment described by program header entry.
  253.  *
  254.  * @param entry Program header entry describing segment to be loaded.
  255.  * @param elf ELF header.
  256.  *
  257.  * @return EE_OK on success, error code otherwise.
  258.  */
  259. int load_segment(int fd, elf_segment_header_t *entry, elf_header_t *elf)
  260. {
  261.     void *a;
  262.     int flags = 0;
  263.     uintptr_t bias;
  264.     int rc;
  265.  
  266.     printf("load segment at addr 0x%x, size 0x%x\n", entry->p_vaddr,
  267.         entry->p_memsz);
  268.    
  269.     bias = (elf->e_type == ET_DYN) ? RTLD_BIAS : 0;
  270.  
  271.     if (entry->p_align > 1) {
  272.         if ((entry->p_offset % entry->p_align) !=
  273.             (entry->p_vaddr % entry->p_align)) {
  274.             printf("align check 1 failed offset%%align=%d, vaddr%%align=%d\n",
  275.             entry->p_offset % entry->p_align,
  276.             entry->p_vaddr % entry->p_align
  277.             );
  278.             return EE_INVALID;
  279.         }
  280.     }
  281.  
  282. /*  if (entry->p_flags & PF_X)
  283.         flags |= AS_AREA_EXEC;
  284.     if (entry->p_flags & PF_W)
  285.         flags |= AS_AREA_WRITE;
  286.     if (entry->p_flags & PF_R)
  287.         flags |= AS_AREA_READ;
  288.     flags |= AS_AREA_CACHEABLE;
  289. */
  290.     /* FIXME: Kernel won't normally allow this, unless you "patch" it */
  291. //  flags = AS_AREA_READ | AS_AREA_WRITE | AS_AREA_EXEC | AS_AREA_CACHEABLE;
  292.     flags = AS_AREA_READ | AS_AREA_WRITE | AS_AREA_CACHEABLE;
  293.  
  294.     /*
  295.      * Check if the virtual address starts on page boundary.
  296.      */
  297.     if (ALIGN_UP(entry->p_vaddr, PAGE_SIZE) != entry->p_vaddr) {
  298.         printf("align check 2 failed - not page-aligned\n");
  299.         printf("vaddr = 0x%x, should be 0x%x\n",
  300.             entry->p_vaddr, ALIGN_UP(entry->p_vaddr, PAGE_SIZE));
  301.         return EE_UNSUPPORTED;
  302.     }
  303.    
  304.     printf("map to p_vaddr=0x%x-0x%x...\n", entry->p_vaddr + bias,
  305.     entry->p_vaddr + bias + ALIGN_UP(entry->p_memsz, PAGE_SIZE));
  306.  
  307.     a = as_area_create((uint8_t *)entry->p_vaddr + bias,
  308.         entry->p_memsz, flags);
  309.     if (a == (void *)(-1)) {
  310.         printf("memory mapping failed\n");
  311.         return EE_MEMORY;
  312.     }
  313.  
  314.     printf("as_area_create(0x%x, 0x%x, %d) -> 0x%x\n",
  315.         entry->p_vaddr+bias, entry->p_memsz, flags, (unsigned)a);
  316.  
  317.     /*
  318.      * Load segment data
  319.      */
  320.     printf("seek to %d\n", entry->p_offset);
  321.     rc = lseek(fd, entry->p_offset, SEEK_SET);
  322.     if (rc < 0) { printf("seek error\n"); return EE_INVALID; }
  323.  
  324.     printf("read 0x%x bytes to address 0x%x\n", entry->p_filesz, entry->p_vaddr+bias);
  325. /*  rc = read(fd, (void *)(entry->p_vaddr + bias), entry->p_filesz);
  326.     if (rc < 0) { printf("read error\n"); return EE_INVALID; }*/
  327.     unsigned left, now;
  328.     uint8_t *dp;
  329.  
  330.     left = entry->p_filesz;
  331.     dp = (uint8_t *)(entry->p_vaddr + bias);
  332.  
  333.     while (left > 0) {
  334.         now = 4096;
  335.         if (now > left) now=left;
  336.         printf("read %d...", now);
  337.         rc = read(fd, dp, now);
  338.         if (rc < 0) { printf("read error\n"); return EE_INVALID; }
  339.         printf("->%d\n", rc);
  340.         left -= now;
  341.         dp += now;
  342.     }
  343.  
  344.     return EE_OK;
  345. }
  346.  
  347. /** Process section header.
  348.  *
  349.  * @param entry Segment header.
  350.  * @param elf ELF header.
  351.  *
  352.  * @return EE_OK on success, error code otherwise.
  353.  */
  354. static int section_header(int fd, elf_header_t *elf)
  355. {
  356.     static elf_section_header_t entry_buf;
  357.     elf_section_header_t *entry = &entry_buf;
  358.     int rc;
  359.  
  360.     rc = read(fd, entry, sizeof(elf_section_header_t));
  361.     if (rc < 0) { printf("read error\n"); return EE_INVALID; }
  362.  
  363.     switch (entry->sh_type) {
  364.     case SHT_PROGBITS:
  365.         if (entry->sh_flags & SHF_TLS) {
  366.             /* .tdata */
  367.         }
  368.         break;
  369.     case SHT_NOBITS:
  370.         if (entry->sh_flags & SHF_TLS) {
  371.             /* .tbss */
  372.         }
  373.         break;
  374.     case SHT_DYNAMIC:
  375.         printf("dynamic section found\n");
  376.         break;
  377.     default:
  378.         break;
  379.     }
  380.    
  381.     return EE_OK;
  382. }
  383.  
  384. /** @}
  385.  */
  386.