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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   Userspace ELF loader.
  38.  *
  39.  * This module allows loading ELF binaries (both executables and
  40.  * shared objects) from VFS. The current implementation allocates
  41.  * anonymous memory, fills it with segment data and then adjusts
  42.  * the memory areas' flags to the final value. In the future,
  43.  * the segments will be mapped directly from the file.
  44.  */
  45.  
  46. #include <stdio.h>
  47. #include <sys/types.h>
  48. #include <align.h>
  49. #include <assert.h>
  50. #include <as.h>
  51. #include <unistd.h>
  52. #include <fcntl.h>
  53. #include <smc.h>
  54. #include <loader/pcb.h>
  55.  
  56. #include "elf.h"
  57. #include "elf_load.h"
  58. #include "arch.h"
  59.  
  60. static char *error_codes[] = {
  61.     "no error",
  62.     "invalid image",
  63.     "address space error",
  64.     "incompatible image",
  65.     "unsupported image type",
  66.     "irrecoverable error"
  67. };
  68.  
  69. static unsigned int elf_load(elf_ld_t *elf, size_t so_bias);
  70. static int segment_header(elf_ld_t *elf, elf_segment_header_t *entry);
  71. static int section_header(elf_ld_t *elf, elf_section_header_t *entry);
  72. static int load_segment(elf_ld_t *elf, elf_segment_header_t *entry);
  73.  
  74. /** Read until the buffer is read in its entirety. */
  75. static int my_read(int fd, char *buf, size_t len)
  76. {
  77.     int cnt = 0;
  78.     do {
  79.         buf += cnt;
  80.         len -= cnt;
  81.         cnt = read(fd, buf, len);
  82.     } while ((cnt > 0) && ((len - cnt) > 0));
  83.  
  84.     return cnt;
  85. }
  86.  
  87. /** Load ELF binary from a file.
  88.  *
  89.  * Load an ELF binary from the specified file. If the file is
  90.  * an executable program, it is loaded unbiased. If it is a shared
  91.  * object, it is loaded with the bias @a so_bias. Some information
  92.  * extracted from the binary is stored in a elf_info_t structure
  93.  * pointed to by @a info.
  94.  *
  95.  * @param file_name Path to the ELF file.
  96.  * @param so_bias   Bias to use if the file is a shared object.
  97.  * @param info      Pointer to a structure for storing information
  98.  *          extracted from the binary.
  99.  *
  100.  * @return EOK on success or negative error code.
  101.  */
  102. int elf_load_file(char *file_name, size_t so_bias, eld_flags_t flags,
  103.     elf_info_t *info)
  104. {
  105.     elf_ld_t elf;
  106.  
  107.     int fd;
  108.     int rc;
  109.  
  110. //  printf("open and read '%s'...\n", file_name);
  111.  
  112.     fd = open(file_name, O_RDONLY);
  113.     if (fd < 0) {
  114.         printf("failed opening file (error %d)\n", fd);
  115.         return -1;
  116.     }
  117.  
  118.     elf.fd = fd;
  119.     elf.info = info;
  120.     elf.flags = flags;
  121.  
  122.     rc = elf_load(&elf, so_bias);
  123.  
  124.     close(fd);
  125.  
  126.     return rc;
  127. }
  128.  
  129. /** Create the program control block (PCB).
  130.  *
  131.  * Fills the program control block @a pcb with information from
  132.  * @a info.
  133.  *
  134.  * @param info  Program info structure
  135.  * @return EOK on success or negative error code
  136.  */
  137. void elf_create_pcb(elf_info_t *info, pcb_t *pcb)
  138. {
  139.     pcb->entry = info->entry;
  140.     pcb->dynamic = info->dynamic;
  141. }
  142.  
  143.  
  144. /** Load an ELF binary.
  145.  *
  146.  * The @a elf structure contains the loader state, including
  147.  * an open file, from which the binary will be loaded,
  148.  * a pointer to the @c info structure etc.
  149.  *
  150.  * @param elf       Pointer to loader state buffer.
  151.  * @param so_bias   Bias to use if the file is a shared object.
  152.  * @return EE_OK on success or EE_xx error code.
  153.  */
  154. static unsigned int elf_load(elf_ld_t *elf, size_t so_bias)
  155. {
  156.     elf_header_t header_buf;
  157.     elf_header_t *header = &header_buf;
  158.     int i, rc;
  159.  
  160.     rc = my_read(elf->fd, header, sizeof(elf_header_t));
  161.     if (rc < 0) {
  162.         printf("read error\n");
  163.         return EE_INVALID;
  164.     }
  165.  
  166.     elf->header = header;
  167.  
  168. //  printf("ELF-load:");
  169.     /* Identify ELF */
  170.     if (header->e_ident[EI_MAG0] != ELFMAG0 ||
  171.         header->e_ident[EI_MAG1] != ELFMAG1 ||
  172.         header->e_ident[EI_MAG2] != ELFMAG2 ||
  173.         header->e_ident[EI_MAG3] != ELFMAG3) {
  174.         printf("invalid header\n");
  175.         return EE_INVALID;
  176.     }
  177.    
  178.     /* Identify ELF compatibility */
  179.     if (header->e_ident[EI_DATA] != ELF_DATA_ENCODING ||
  180.         header->e_machine != ELF_MACHINE ||
  181.         header->e_ident[EI_VERSION] != EV_CURRENT ||
  182.         header->e_version != EV_CURRENT ||
  183.         header->e_ident[EI_CLASS] != ELF_CLASS) {
  184.         printf("incompatible data/version/class\n");
  185.         return EE_INCOMPATIBLE;
  186.     }
  187.  
  188.     if (header->e_phentsize != sizeof(elf_segment_header_t)) {
  189.         printf("e_phentsize:%d != %d\n", header->e_phentsize,
  190.             sizeof(elf_segment_header_t));
  191.         return EE_INCOMPATIBLE;
  192.     }
  193.  
  194.     if (header->e_shentsize != sizeof(elf_section_header_t)) {
  195.         printf("e_shentsize:%d != %d\n", header->e_shentsize,
  196.             sizeof(elf_section_header_t));
  197.         return EE_INCOMPATIBLE;
  198.     }
  199.  
  200.     /* Check if the object type is supported. */
  201.     if (header->e_type != ET_EXEC && header->e_type != ET_DYN) {
  202.         printf("Object type %d is not supported\n", header->e_type);
  203.         return EE_UNSUPPORTED;
  204.     }
  205.  
  206.     /* Shared objects can be loaded with a bias */
  207. //  printf("Object type: %d\n", header->e_type);
  208.     if (header->e_type == ET_DYN)
  209.         elf->bias = so_bias;
  210.     else
  211.         elf->bias = 0;
  212.  
  213. //  printf("Bias set to 0x%x\n", elf->bias);
  214.     elf->info->interp = NULL;
  215.     elf->info->dynamic = NULL;
  216.  
  217. //  printf("parse segments\n");
  218.  
  219.     /* Walk through all segment headers and process them. */
  220.     for (i = 0; i < header->e_phnum; i++) {
  221.         elf_segment_header_t segment_hdr;
  222.  
  223.         /* Seek to start of segment header */
  224.         lseek(elf->fd, header->e_phoff
  225.                 + i * sizeof(elf_segment_header_t), SEEK_SET);
  226.  
  227.         rc = my_read(elf->fd, &segment_hdr,
  228.             sizeof(elf_segment_header_t));
  229.         if (rc < 0) {
  230.             printf("read error\n");
  231.             return EE_INVALID;
  232.         }
  233.  
  234.         rc = segment_header(elf, &segment_hdr);
  235.         if (rc != EE_OK)
  236.             return rc;
  237.     }
  238.  
  239. //  printf("parse sections\n");
  240.  
  241.     /* Inspect all section headers and proccess them. */
  242.     for (i = 0; i < header->e_shnum; i++) {
  243.         elf_section_header_t section_hdr;
  244.  
  245.         /* Seek to start of section header */
  246.         lseek(elf->fd, header->e_shoff
  247.             + i * sizeof(elf_section_header_t), SEEK_SET);
  248.  
  249.         rc = my_read(elf->fd, &section_hdr,
  250.             sizeof(elf_section_header_t));
  251.         if (rc < 0) {
  252.             printf("read error\n");
  253.             return EE_INVALID;
  254.         }
  255.  
  256.         rc = section_header(elf, &section_hdr);
  257.         if (rc != EE_OK)
  258.             return rc;
  259.     }
  260.  
  261.     elf->info->entry =
  262.         (entry_point_t)((uint8_t *)header->e_entry + elf->bias);
  263.  
  264. //  printf("done\n");
  265.  
  266.     return EE_OK;
  267. }
  268.  
  269. /** Print error message according to error code.
  270.  *
  271.  * @param rc Return code returned by elf_load().
  272.  *
  273.  * @return NULL terminated description of error.
  274.  */
  275. char *elf_error(unsigned int rc)
  276. {
  277.     assert(rc < sizeof(error_codes) / sizeof(char *));
  278.  
  279.     return error_codes[rc];
  280. }
  281.  
  282. /** Process segment header.
  283.  *
  284.  * @param entry Segment header.
  285.  *
  286.  * @return EE_OK on success, error code otherwise.
  287.  */
  288. static int segment_header(elf_ld_t *elf, elf_segment_header_t *entry)
  289. {
  290.     switch (entry->p_type) {
  291.     case PT_NULL:
  292.     case PT_PHDR:
  293.         break;
  294.     case PT_LOAD:
  295.         return load_segment(elf, entry);
  296.         break;
  297.     case PT_INTERP:
  298.         /* Assume silently interp == "/app/dload" */
  299.         elf->info->interp = "/app/dload";
  300.         break;
  301.     case PT_DYNAMIC:
  302.     case PT_SHLIB:
  303.     case PT_NOTE:
  304.     case PT_LOPROC:
  305.     case PT_HIPROC:
  306.     default:
  307.         printf("segment p_type %d unknown\n", entry->p_type);
  308.         return EE_UNSUPPORTED;
  309.         break;
  310.     }
  311.     return EE_OK;
  312. }
  313.  
  314. /** Load segment described by program header entry.
  315.  *
  316.  * @param elf   Loader state.
  317.  * @param entry Program header entry describing segment to be loaded.
  318.  *
  319.  * @return EE_OK on success, error code otherwise.
  320.  */
  321. int load_segment(elf_ld_t *elf, elf_segment_header_t *entry)
  322. {
  323.     void *a;
  324.     int flags = 0;
  325.     uintptr_t bias;
  326.     uintptr_t base;
  327.     size_t mem_sz;
  328.     int rc;
  329.  
  330. //  printf("load segment at addr 0x%x, size 0x%x\n", entry->p_vaddr,
  331. //      entry->p_memsz);
  332.    
  333.     bias = elf->bias;
  334.  
  335.     if (entry->p_align > 1) {
  336.         if ((entry->p_offset % entry->p_align) !=
  337.             (entry->p_vaddr % entry->p_align)) {
  338.             printf("align check 1 failed offset%%align=%d, "
  339.                 "vaddr%%align=%d\n",
  340.                 entry->p_offset % entry->p_align,
  341.                 entry->p_vaddr % entry->p_align
  342.             );
  343.             return EE_INVALID;
  344.         }
  345.     }
  346.  
  347.     /* Final flags that will be set for the memory area */
  348.  
  349.     if (entry->p_flags & PF_X)
  350.         flags |= AS_AREA_EXEC;
  351.     if (entry->p_flags & PF_W)
  352.         flags |= AS_AREA_WRITE;
  353.     if (entry->p_flags & PF_R)
  354.         flags |= AS_AREA_READ;
  355.     flags |= AS_AREA_CACHEABLE;
  356.    
  357.     base = ALIGN_DOWN(entry->p_vaddr, PAGE_SIZE);
  358.     mem_sz = entry->p_memsz + (entry->p_vaddr - base);
  359.  
  360. //  printf("map to p_vaddr=0x%x-0x%x...\n", entry->p_vaddr + bias,
  361. //  entry->p_vaddr + bias + ALIGN_UP(entry->p_memsz, PAGE_SIZE));
  362.  
  363.     /*
  364.      * For the course of loading, the area needs to be readable
  365.      * and writeable.
  366.      */
  367.     a = as_area_create((uint8_t *)base + bias, mem_sz,
  368.         AS_AREA_READ | AS_AREA_WRITE | AS_AREA_CACHEABLE);
  369.     if (a == (void *)(-1)) {
  370.         printf("memory mapping failed\n");
  371.         return EE_MEMORY;
  372.     }
  373.  
  374. //  printf("as_area_create(0x%lx, 0x%x, %d) -> 0x%lx\n",
  375. //      entry->p_vaddr+bias, entry->p_memsz, flags, (uintptr_t)a);
  376.  
  377.     /*
  378.      * Load segment data
  379.      */
  380. //  printf("seek to %d\n", entry->p_offset);
  381.     rc = lseek(elf->fd, entry->p_offset, SEEK_SET);
  382.     if (rc < 0) {
  383.         printf("seek error\n");
  384.         return EE_INVALID;
  385.     }
  386.  
  387. //  printf("read 0x%x bytes to address 0x%x\n", entry->p_filesz, entry->p_vaddr+bias);
  388. /*  rc = read(fd, (void *)(entry->p_vaddr + bias), entry->p_filesz);
  389.     if (rc < 0) { printf("read error\n"); return EE_INVALID; }*/
  390.  
  391.     /* Long reads are not possible yet. Load segment picewise */
  392.  
  393.     unsigned left, now;
  394.     uint8_t *dp;
  395.  
  396.     left = entry->p_filesz;
  397.     dp = (uint8_t *)(entry->p_vaddr + bias);
  398.  
  399.     while (left > 0) {
  400.         now = 16384;
  401.         if (now > left) now = left;
  402.  
  403. //      printf("read %d...", now);
  404.         rc = my_read(elf->fd, dp, now);
  405. //      printf("->%d\n", rc);
  406.  
  407.         if (rc < 0) {
  408.             printf("read error\n");
  409.             return EE_INVALID;
  410.         }
  411.  
  412.         left -= now;
  413.         dp += now;
  414.     }
  415.  
  416.     /*
  417.      * The caller wants to modify the segments first. He will then
  418.      * need to set the right access mode and ensure SMC coherence.
  419.      */
  420.     if ((elf->flags & ELDF_RW) != 0) return EE_OK;
  421.  
  422. //  printf("set area flags to %d\n", flags);
  423.     rc = as_area_change_flags((uint8_t *)entry->p_vaddr + bias, flags);
  424.     if (rc != 0) {
  425.         printf("failed to set memory area flags\n");
  426.         return EE_MEMORY;
  427.     }
  428.  
  429.     if (flags & AS_AREA_EXEC) {
  430.         /* Enforce SMC coherence for the segment */
  431.         if (smc_coherence(entry->p_vaddr + bias, entry->p_filesz))
  432.             return EE_MEMORY;
  433.     }
  434.  
  435.     return EE_OK;
  436. }
  437.  
  438. /** Process section header.
  439.  *
  440.  * @param elf   Loader state.
  441.  * @param entry Segment header.
  442.  *
  443.  * @return EE_OK on success, error code otherwise.
  444.  */
  445. static int section_header(elf_ld_t *elf, elf_section_header_t *entry)
  446. {
  447.     switch (entry->sh_type) {
  448.     case SHT_PROGBITS:
  449.         if (entry->sh_flags & SHF_TLS) {
  450.             /* .tdata */
  451.         }
  452.         break;
  453.     case SHT_NOBITS:
  454.         if (entry->sh_flags & SHF_TLS) {
  455.             /* .tbss */
  456.         }
  457.         break;
  458.     case SHT_DYNAMIC:
  459.         /* Record pointer to dynamic section into info structure */
  460.         elf->info->dynamic =
  461.             (void *)((uint8_t *)entry->sh_addr + elf->bias);
  462.         printf("dynamic section found at 0x%x\n",
  463.             (uintptr_t)elf->info->dynamic);
  464.         break;
  465.     default:
  466.         break;
  467.     }
  468.    
  469.     return EE_OK;
  470. }
  471.  
  472. /** @}
  473.  */
  474.