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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.     pcb->rtld_runtime = NULL;
  142. }
  143.  
  144.  
  145. /** Load an ELF binary.
  146.  *
  147.  * The @a elf structure contains the loader state, including
  148.  * an open file, from which the binary will be loaded,
  149.  * a pointer to the @c info structure etc.
  150.  *
  151.  * @param elf       Pointer to loader state buffer.
  152.  * @param so_bias   Bias to use if the file is a shared object.
  153.  * @return EE_OK on success or EE_xx error code.
  154.  */
  155. static unsigned int elf_load(elf_ld_t *elf, size_t so_bias)
  156. {
  157.     elf_header_t header_buf;
  158.     elf_header_t *header = &header_buf;
  159.     int i, rc;
  160.  
  161.     rc = my_read(elf->fd, header, sizeof(elf_header_t));
  162.     if (rc < 0) {
  163.         printf("read error\n");
  164.         return EE_INVALID;
  165.     }
  166.  
  167.     elf->header = header;
  168.  
  169. //  printf("ELF-load:");
  170.     /* Identify ELF */
  171.     if (header->e_ident[EI_MAG0] != ELFMAG0 ||
  172.         header->e_ident[EI_MAG1] != ELFMAG1 ||
  173.         header->e_ident[EI_MAG2] != ELFMAG2 ||
  174.         header->e_ident[EI_MAG3] != ELFMAG3) {
  175.         printf("invalid header\n");
  176.         return EE_INVALID;
  177.     }
  178.    
  179.     /* Identify ELF compatibility */
  180.     if (header->e_ident[EI_DATA] != ELF_DATA_ENCODING ||
  181.         header->e_machine != ELF_MACHINE ||
  182.         header->e_ident[EI_VERSION] != EV_CURRENT ||
  183.         header->e_version != EV_CURRENT ||
  184.         header->e_ident[EI_CLASS] != ELF_CLASS) {
  185.         printf("incompatible data/version/class\n");
  186.         return EE_INCOMPATIBLE;
  187.     }
  188.  
  189.     if (header->e_phentsize != sizeof(elf_segment_header_t)) {
  190.         printf("e_phentsize:%d != %d\n", header->e_phentsize,
  191.             sizeof(elf_segment_header_t));
  192.         return EE_INCOMPATIBLE;
  193.     }
  194.  
  195.     if (header->e_shentsize != sizeof(elf_section_header_t)) {
  196.         printf("e_shentsize:%d != %d\n", header->e_shentsize,
  197.             sizeof(elf_section_header_t));
  198.         return EE_INCOMPATIBLE;
  199.     }
  200.  
  201.     /* Check if the object type is supported. */
  202.     if (header->e_type != ET_EXEC && header->e_type != ET_DYN) {
  203.         printf("Object type %d is not supported\n", header->e_type);
  204.         return EE_UNSUPPORTED;
  205.     }
  206.  
  207.     /* Shared objects can be loaded with a bias */
  208. //  printf("Object type: %d\n", header->e_type);
  209.     if (header->e_type == ET_DYN)
  210.         elf->bias = so_bias;
  211.     else
  212.         elf->bias = 0;
  213.  
  214. //  printf("Bias set to 0x%x\n", elf->bias);
  215.     elf->info->interp = NULL;
  216.     elf->info->dynamic = NULL;
  217.  
  218. //  printf("parse segments\n");
  219.  
  220.     /* Walk through all segment headers and process them. */
  221.     for (i = 0; i < header->e_phnum; i++) {
  222.         elf_segment_header_t segment_hdr;
  223.  
  224.         /* Seek to start of segment header */
  225.         lseek(elf->fd, header->e_phoff
  226.                 + i * sizeof(elf_segment_header_t), SEEK_SET);
  227.  
  228.         rc = my_read(elf->fd, &segment_hdr,
  229.             sizeof(elf_segment_header_t));
  230.         if (rc < 0) {
  231.             printf("read error\n");
  232.             return EE_INVALID;
  233.         }
  234.  
  235.         rc = segment_header(elf, &segment_hdr);
  236.         if (rc != EE_OK)
  237.             return rc;
  238.     }
  239.  
  240. //  printf("parse sections\n");
  241.  
  242.     /* Inspect all section headers and proccess them. */
  243.     for (i = 0; i < header->e_shnum; i++) {
  244.         elf_section_header_t section_hdr;
  245.  
  246.         /* Seek to start of section header */
  247.         lseek(elf->fd, header->e_shoff
  248.             + i * sizeof(elf_section_header_t), SEEK_SET);
  249.  
  250.         rc = my_read(elf->fd, &section_hdr,
  251.             sizeof(elf_section_header_t));
  252.         if (rc < 0) {
  253.             printf("read error\n");
  254.             return EE_INVALID;
  255.         }
  256.  
  257.         rc = section_header(elf, &section_hdr);
  258.         if (rc != EE_OK)
  259.             return rc;
  260.     }
  261.  
  262.     elf->info->entry =
  263.         (entry_point_t)((uint8_t *)header->e_entry + elf->bias);
  264.  
  265. //  printf("done\n");
  266.  
  267.     return EE_OK;
  268. }
  269.  
  270. /** Print error message according to error code.
  271.  *
  272.  * @param rc Return code returned by elf_load().
  273.  *
  274.  * @return NULL terminated description of error.
  275.  */
  276. char *elf_error(unsigned int rc)
  277. {
  278.     assert(rc < sizeof(error_codes) / sizeof(char *));
  279.  
  280.     return error_codes[rc];
  281. }
  282.  
  283. /** Process segment header.
  284.  *
  285.  * @param entry Segment header.
  286.  *
  287.  * @return EE_OK on success, error code otherwise.
  288.  */
  289. static int segment_header(elf_ld_t *elf, elf_segment_header_t *entry)
  290. {
  291.     switch (entry->p_type) {
  292.     case PT_NULL:
  293.     case PT_PHDR:
  294.         break;
  295.     case PT_LOAD:
  296.         return load_segment(elf, entry);
  297.         break;
  298.     case PT_INTERP:
  299.         /* Assume silently interp == "/app/dload" */
  300.         elf->info->interp = "/app/dload";
  301.         break;
  302.     case PT_DYNAMIC:
  303.         /* Record pointer to dynamic section into info structure */
  304.         elf->info->dynamic =
  305.             (void *)((uint8_t *)entry->p_vaddr + elf->bias);
  306.         printf("dynamic section found at 0x%x\n",
  307.             (uintptr_t)elf->info->dynamic);
  308.         break;
  309.     case PT_SHLIB:
  310.     case PT_NOTE:
  311.     case PT_LOPROC:
  312.     case PT_HIPROC:
  313.     default:
  314.         printf("segment p_type %d unknown\n", entry->p_type);
  315.         return EE_UNSUPPORTED;
  316.         break;
  317.     }
  318.     return EE_OK;
  319. }
  320.  
  321. /** Load segment described by program header entry.
  322.  *
  323.  * @param elf   Loader state.
  324.  * @param entry Program header entry describing segment to be loaded.
  325.  *
  326.  * @return EE_OK on success, error code otherwise.
  327.  */
  328. int load_segment(elf_ld_t *elf, elf_segment_header_t *entry)
  329. {
  330.     void *a;
  331.     int flags = 0;
  332.     uintptr_t bias;
  333.     uintptr_t base;
  334.     size_t mem_sz;
  335.     int rc;
  336.  
  337. //  printf("load segment at addr 0x%x, size 0x%x\n", entry->p_vaddr,
  338. //      entry->p_memsz);
  339.    
  340.     bias = elf->bias;
  341.  
  342.     if (entry->p_align > 1) {
  343.         if ((entry->p_offset % entry->p_align) !=
  344.             (entry->p_vaddr % entry->p_align)) {
  345.             printf("align check 1 failed offset%%align=%d, "
  346.                 "vaddr%%align=%d\n",
  347.                 entry->p_offset % entry->p_align,
  348.                 entry->p_vaddr % entry->p_align
  349.             );
  350.             return EE_INVALID;
  351.         }
  352.     }
  353.  
  354.     /* Final flags that will be set for the memory area */
  355.  
  356.     if (entry->p_flags & PF_X)
  357.         flags |= AS_AREA_EXEC;
  358.     if (entry->p_flags & PF_W)
  359.         flags |= AS_AREA_WRITE;
  360.     if (entry->p_flags & PF_R)
  361.         flags |= AS_AREA_READ;
  362.     flags |= AS_AREA_CACHEABLE;
  363.    
  364.     base = ALIGN_DOWN(entry->p_vaddr, PAGE_SIZE);
  365.     mem_sz = entry->p_memsz + (entry->p_vaddr - base);
  366.  
  367. //  printf("map to p_vaddr=0x%x-0x%x...\n", entry->p_vaddr + bias,
  368. //  entry->p_vaddr + bias + ALIGN_UP(entry->p_memsz, PAGE_SIZE));
  369.  
  370.     /*
  371.      * For the course of loading, the area needs to be readable
  372.      * and writeable.
  373.      */
  374.     a = as_area_create((uint8_t *)base + bias, mem_sz,
  375.         AS_AREA_READ | AS_AREA_WRITE | AS_AREA_CACHEABLE);
  376.     if (a == (void *)(-1)) {
  377.         printf("memory mapping failed\n");
  378.         return EE_MEMORY;
  379.     }
  380.  
  381. //  printf("as_area_create(0x%lx, 0x%x, %d) -> 0x%lx\n",
  382. //      entry->p_vaddr+bias, entry->p_memsz, flags, (uintptr_t)a);
  383.  
  384.     /*
  385.      * Load segment data
  386.      */
  387. //  printf("seek to %d\n", entry->p_offset);
  388.     rc = lseek(elf->fd, entry->p_offset, SEEK_SET);
  389.     if (rc < 0) {
  390.         printf("seek error\n");
  391.         return EE_INVALID;
  392.     }
  393.  
  394. //  printf("read 0x%x bytes to address 0x%x\n", entry->p_filesz, entry->p_vaddr+bias);
  395. /*  rc = read(fd, (void *)(entry->p_vaddr + bias), entry->p_filesz);
  396.     if (rc < 0) { printf("read error\n"); return EE_INVALID; }*/
  397.  
  398.     /* Long reads are not possible yet. Load segment picewise */
  399.  
  400.     unsigned left, now;
  401.     uint8_t *dp;
  402.  
  403.     left = entry->p_filesz;
  404.     dp = (uint8_t *)(entry->p_vaddr + bias);
  405.  
  406.     while (left > 0) {
  407.         now = 16384;
  408.         if (now > left) now = left;
  409.  
  410. //      printf("read %d...", now);
  411.         rc = my_read(elf->fd, dp, now);
  412. //      printf("->%d\n", rc);
  413.  
  414.         if (rc < 0) {
  415.             printf("read error\n");
  416.             return EE_INVALID;
  417.         }
  418.  
  419.         left -= now;
  420.         dp += now;
  421.     }
  422.  
  423.     /*
  424.      * The caller wants to modify the segments first. He will then
  425.      * need to set the right access mode and ensure SMC coherence.
  426.      */
  427.     if ((elf->flags & ELDF_RW) != 0) return EE_OK;
  428.  
  429. //  printf("set area flags to %d\n", flags);
  430.     rc = as_area_change_flags((uint8_t *)entry->p_vaddr + bias, flags);
  431.     if (rc != 0) {
  432.         printf("failed to set memory area flags\n");
  433.         return EE_MEMORY;
  434.     }
  435.  
  436.     if (flags & AS_AREA_EXEC) {
  437.         /* Enforce SMC coherence for the segment */
  438.         if (smc_coherence(entry->p_vaddr + bias, entry->p_filesz))
  439.             return EE_MEMORY;
  440.     }
  441.  
  442.     return EE_OK;
  443. }
  444.  
  445. /** Process section header.
  446.  *
  447.  * @param elf   Loader state.
  448.  * @param entry Segment header.
  449.  *
  450.  * @return EE_OK on success, error code otherwise.
  451.  */
  452. static int section_header(elf_ld_t *elf, elf_section_header_t *entry)
  453. {
  454.     switch (entry->sh_type) {
  455.     case SHT_PROGBITS:
  456.         if (entry->sh_flags & SHF_TLS) {
  457.             /* .tdata */
  458.         }
  459.         break;
  460.     case SHT_NOBITS:
  461.         if (entry->sh_flags & SHF_TLS) {
  462.             /* .tbss */
  463.         }
  464.         break;
  465.     case SHT_DYNAMIC:
  466.         break;
  467.     default:
  468.         break;
  469.     }
  470.    
  471.     return EE_OK;
  472. }
  473.  
  474. /** @}
  475.  */
  476.