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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. #define DPRINTF(...)
  61.  
  62. static char *error_codes[] = {
  63.     "no error",
  64.     "invalid image",
  65.     "address space error",
  66.     "incompatible image",
  67.     "unsupported image type",
  68.     "irrecoverable error"
  69. };
  70.  
  71. static unsigned int elf_load(elf_ld_t *elf, size_t so_bias);
  72. static int segment_header(elf_ld_t *elf, elf_segment_header_t *entry);
  73. static int section_header(elf_ld_t *elf, elf_section_header_t *entry);
  74. static int load_segment(elf_ld_t *elf, elf_segment_header_t *entry);
  75.  
  76. /** Read until the buffer is read in its entirety. */
  77. static int my_read(int fd, void *buf, size_t len)
  78. {
  79.     int cnt = 0;
  80.     do {
  81.         buf += cnt;
  82.         len -= cnt;
  83.         cnt = read(fd, buf, len);
  84.     } while ((cnt > 0) && ((len - cnt) > 0));
  85.  
  86.     return cnt;
  87. }
  88.  
  89. /** Load ELF binary from a file.
  90.  *
  91.  * Load an ELF binary from the specified file. If the file is
  92.  * an executable program, it is loaded unbiased. If it is a shared
  93.  * object, it is loaded with the bias @a so_bias. Some information
  94.  * extracted from the binary is stored in a elf_info_t structure
  95.  * pointed to by @a info.
  96.  *
  97.  * @param file_name Path to the ELF file.
  98.  * @param so_bias   Bias to use if the file is a shared object.
  99.  * @param info      Pointer to a structure for storing information
  100.  *          extracted from the binary.
  101.  *
  102.  * @return EOK on success or negative error code.
  103.  */
  104. int elf_load_file(char *file_name, size_t so_bias, eld_flags_t flags,
  105.     elf_info_t *info)
  106. {
  107.     elf_ld_t elf;
  108.  
  109.     int fd;
  110.     int rc;
  111.  
  112.     fd = open(file_name, O_RDONLY);
  113.     if (fd < 0) {
  114.         DPRINTF("failed opening file\n");
  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.         DPRINTF("Read error.\n");
  164.         return EE_INVALID;
  165.     }
  166.  
  167.     elf->header = header;
  168.  
  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.         DPRINTF("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.         DPRINTF("Incompatible data/version/class.\n");
  185.         return EE_INCOMPATIBLE;
  186.     }
  187.  
  188.     if (header->e_phentsize != sizeof(elf_segment_header_t)) {
  189.         DPRINTF("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.         DPRINTF("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.         DPRINTF("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.     if (header->e_type == ET_DYN)
  208.         elf->bias = so_bias;
  209.     else
  210.         elf->bias = 0;
  211.  
  212.     elf->info->interp = NULL;
  213.     elf->info->dynamic = NULL;
  214.  
  215.     /* Walk through all segment headers and process them. */
  216.     for (i = 0; i < header->e_phnum; i++) {
  217.         elf_segment_header_t segment_hdr;
  218.  
  219.         /* Seek to start of segment header */
  220.         lseek(elf->fd, header->e_phoff
  221.                 + i * sizeof(elf_segment_header_t), SEEK_SET);
  222.  
  223.         rc = my_read(elf->fd, &segment_hdr,
  224.             sizeof(elf_segment_header_t));
  225.         if (rc < 0) {
  226.             DPRINTF("Read error.\n");
  227.             return EE_INVALID;
  228.         }
  229.  
  230.         rc = segment_header(elf, &segment_hdr);
  231.         if (rc != EE_OK)
  232.             return rc;
  233.     }
  234.  
  235.     DPRINTF("Parse sections.\n");
  236.  
  237.     /* Inspect all section headers and proccess them. */
  238.     for (i = 0; i < header->e_shnum; i++) {
  239.         elf_section_header_t section_hdr;
  240.  
  241.         /* Seek to start of section header */
  242.         lseek(elf->fd, header->e_shoff
  243.             + i * sizeof(elf_section_header_t), SEEK_SET);
  244.  
  245.         rc = my_read(elf->fd, &section_hdr,
  246.             sizeof(elf_section_header_t));
  247.         if (rc < 0) {
  248.             DPRINTF("Read error.\n");
  249.             return EE_INVALID;
  250.         }
  251.  
  252.         rc = section_header(elf, &section_hdr);
  253.         if (rc != EE_OK)
  254.             return rc;
  255.     }
  256.  
  257.     elf->info->entry =
  258.         (entry_point_t)((uint8_t *)header->e_entry + elf->bias);
  259.  
  260.     DPRINTF("Done.\n");
  261.  
  262.     return EE_OK;
  263. }
  264.  
  265. /** Print error message according to error code.
  266.  *
  267.  * @param rc Return code returned by elf_load().
  268.  *
  269.  * @return NULL terminated description of error.
  270.  */
  271. char *elf_error(unsigned int rc)
  272. {
  273.     assert(rc < sizeof(error_codes) / sizeof(char *));
  274.  
  275.     return error_codes[rc];
  276. }
  277.  
  278. /** Process segment header.
  279.  *
  280.  * @param entry Segment header.
  281.  *
  282.  * @return EE_OK on success, error code otherwise.
  283.  */
  284. static int segment_header(elf_ld_t *elf, elf_segment_header_t *entry)
  285. {
  286.     switch (entry->p_type) {
  287.     case PT_NULL:
  288.     case PT_PHDR:
  289.         break;
  290.     case PT_LOAD:
  291.         return load_segment(elf, entry);
  292.         break;
  293.     case PT_INTERP:
  294.         /* Assume silently interp == "/app/dload" */
  295.         elf->info->interp = "/app/dload";
  296.         break;
  297.     case PT_DYNAMIC:
  298.         /* Record pointer to dynamic section into info structure */
  299.         elf->info->dynamic =
  300.             (void *)((uint8_t *)entry->p_vaddr + elf->bias);
  301.         DPRINTF("dynamic section found at 0x%x\n",
  302.             (uintptr_t)elf->info->dynamic);
  303.         break;
  304.     case 0x70000000:
  305.         /* FIXME: MIPS reginfo */
  306.         break;
  307.     case PT_SHLIB:
  308.     case PT_NOTE:
  309. //  case PT_LOPROC:
  310. //  case PT_HIPROC:
  311.     default:
  312.         DPRINTF("Segment p_type %d unknown.\n", entry->p_type);
  313.         return EE_UNSUPPORTED;
  314.         break;
  315.     }
  316.     return EE_OK;
  317. }
  318.  
  319. /** Load segment described by program header entry.
  320.  *
  321.  * @param elf   Loader state.
  322.  * @param entry Program header entry describing segment to be loaded.
  323.  *
  324.  * @return EE_OK on success, error code otherwise.
  325.  */
  326. int load_segment(elf_ld_t *elf, elf_segment_header_t *entry)
  327. {
  328.     void *a;
  329.     int flags = 0;
  330.     uintptr_t bias;
  331.     uintptr_t base;
  332.     void *seg_ptr;
  333.     uintptr_t seg_addr;
  334.     size_t mem_sz;
  335.     int rc;
  336.  
  337.     bias = elf->bias;
  338.  
  339.     seg_addr = entry->p_vaddr + bias;
  340.     seg_ptr = (void *) seg_addr;
  341.  
  342.     DPRINTF("Load segment at addr 0x%x, size 0x%x\n", seg_addr,
  343.         entry->p_memsz);   
  344.  
  345.     if (entry->p_align > 1) {
  346.         if ((entry->p_offset % entry->p_align) !=
  347.             (seg_addr % entry->p_align)) {
  348.             DPRINTF("Align check 1 failed offset%%align=%d, "
  349.                 "vaddr%%align=%d\n",
  350.                 entry->p_offset % entry->p_align,
  351.                 seg_addr % entry->p_align
  352.             );
  353.             return EE_INVALID;
  354.         }
  355.     }
  356.  
  357.     /* Final flags that will be set for the memory area */
  358.  
  359.     if (entry->p_flags & PF_X)
  360.         flags |= AS_AREA_EXEC;
  361.     if (entry->p_flags & PF_W)
  362.         flags |= AS_AREA_WRITE;
  363.     if (entry->p_flags & PF_R)
  364.         flags |= AS_AREA_READ;
  365.     flags |= AS_AREA_CACHEABLE;
  366.    
  367.     base = ALIGN_DOWN(entry->p_vaddr, PAGE_SIZE);
  368.     mem_sz = entry->p_memsz + (entry->p_vaddr - base);
  369.  
  370.     DPRINTF("Map to seg_addr=0x%x-0x%x.\n", seg_addr,
  371.     entry->p_vaddr + bias + ALIGN_UP(entry->p_memsz, PAGE_SIZE));
  372.  
  373.     /*
  374.      * For the course of loading, the area needs to be readable
  375.      * and writeable.
  376.      */
  377.     a = as_area_create((uint8_t *)base + bias, mem_sz,
  378.         AS_AREA_READ | AS_AREA_WRITE | AS_AREA_CACHEABLE);
  379.     if (a == (void *)(-1)) {
  380.         DPRINTF("memory mapping failed (0x%x, %d)\n",
  381.             base+bias, mem_sz);
  382.         return EE_MEMORY;
  383.     }
  384.  
  385.     DPRINTF("as_area_create(0x%lx, 0x%x, %d) -> 0x%lx\n",
  386.         base + bias, mem_sz, flags, (uintptr_t)a);
  387.  
  388.     /*
  389.      * Load segment data
  390.      */
  391.     rc = lseek(elf->fd, entry->p_offset, SEEK_SET);
  392.     if (rc < 0) {
  393.         printf("seek error\n");
  394.         return EE_INVALID;
  395.     }
  396.  
  397. /*  rc = read(fd, (void *)(entry->p_vaddr + bias), entry->p_filesz);
  398.     if (rc < 0) { printf("read error\n"); return EE_INVALID; }*/
  399.  
  400.     /* Long reads are not possible yet. Load segment piecewise. */
  401.  
  402.     unsigned left, now;
  403.     uint8_t *dp;
  404.  
  405.     left = entry->p_filesz;
  406.     dp = seg_ptr;
  407.  
  408.     while (left > 0) {
  409.         now = 16384;
  410.         if (now > left) now = left;
  411.  
  412.         rc = my_read(elf->fd, dp, now);
  413.  
  414.         if (rc < 0) {
  415.             DPRINTF("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(seg_ptr, flags);
  431.     if (rc != 0) {
  432.         DPRINTF("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(seg_ptr, 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.