usr/src/boot/sys/boot/common/self_reloc.c

   1 /*-
   2  * Copyright (c) 2008-2010 Rui Paulo <rpaulo@FreeBSD.org>
   3  * All rights reserved.
   4  *
   5  * Redistribution and use in source and binary forms, with or without
   6  * modification, are permitted provided that the following conditions
   7  * are met:
   8  * 1. Redistributions of source code must retain the above copyright
   9  *    notice, this list of conditions and the following disclaimer.
  10  * 2. Redistributions in binary form must reproduce the above copyright
  11  *    notice, this list of conditions and the following disclaimer in the
  12  *    documentation and/or other materials provided with the distribution.
  13  *
  14  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
  15  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  16  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  17  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
  18  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  19  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  20  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  21  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  22  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  23  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  24  * SUCH DAMAGE.
  25  */
  26
  27 #include <sys/cdefs.h>
  28
  29 #include <sys/types.h>
  30 #include <elf.h>
  31 #include <bootstrap.h>
  32
  33 #if defined(__aarch64__) || defined(__amd64__)
  34 #define ElfW_Rel        Elf64_Rela
  35 #define ElfW_Dyn        Elf64_Dyn
  36 #define ELFW_R_TYPE     ELF64_R_TYPE
  37 #define ELF_RELA
  38 #elif defined(__arm__) || defined(__i386__)
  39 #define ElfW_Rel        Elf32_Rel
  40 #define ElfW_Dyn        Elf32_Dyn
  41 #define ELFW_R_TYPE     ELF32_R_TYPE
  42 #else
  43 #error architecture not supported
  44 #endif
  45 #if defined(__aarch64__)
  46 #define RELOC_TYPE_NONE         R_AARCH64_NONE
  47 #define RELOC_TYPE_RELATIVE     R_AARCH64_RELATIVE
  48 #elif defined(__amd64__)
  49 #define RELOC_TYPE_NONE         R_X86_64_NONE
  50 #define RELOC_TYPE_RELATIVE     R_X86_64_RELATIVE
  51 #elif defined(__arm__)
  52 #define RELOC_TYPE_NONE         R_ARM_NONE
  53 #define RELOC_TYPE_RELATIVE     R_ARM_RELATIVE
  54 #elif defined(__i386__)
  55 #define RELOC_TYPE_NONE         R_386_NONE
  56 #define RELOC_TYPE_RELATIVE     R_386_RELATIVE
  57 #endif
  58
  59 void self_reloc(Elf_Addr baseaddr, ElfW_Dyn *dynamic);
  60
  61 /*
  62  * A simple elf relocator.
  63  */
  64 void
  65 self_reloc(Elf_Addr baseaddr, ElfW_Dyn *dynamic)
  66 {
  67         Elf_Word relsz, relent;
  68         Elf_Addr *newaddr;
  69         ElfW_Rel *rel = 0;
  70         ElfW_Dyn *dynp;
  71
  72         /*
  73          * Find the relocation address, its size and the relocation entry.
  74          */
  75         relsz = 0;
  76         relent = 0;
  77         for (dynp = dynamic; dynp->d_tag != DT_NULL; dynp++) {
  78                 switch (dynp->d_tag) {
  79                 case DT_REL:
  80                 case DT_RELA:
  81                         rel = (ElfW_Rel *)(dynp->d_un.d_ptr + baseaddr);
  82                         break;
  83                 case DT_RELSZ:
  84                 case DT_RELASZ:
  85                         relsz = dynp->d_un.d_val;
  86                         break;
  87                 case DT_RELENT:
  88                 case DT_RELAENT:
  89                         relent = dynp->d_un.d_val;
  90                         break;
  91                 default:
  92                         break;
  93                 }
  94         }
  95
  96         /*
  97          * Perform the actual relocation. We rely on the object having been
  98          * linked at 0, so that the difference between the load and link
  99          * address is the same as the load address.
 100          */
 101         for (; relsz > 0; relsz -= relent) {
 102                 switch (ELFW_R_TYPE(rel->r_info)) {
 103                 case RELOC_TYPE_NONE:
 104                         /* No relocation needs be performed. */
 105                         break;
 106
 107                 case RELOC_TYPE_RELATIVE:
 108                         newaddr = (Elf_Addr *)(rel->r_offset + baseaddr);
 109 #ifdef ELF_RELA
 110                         /* Addend relative to the base address. */
 111                         *newaddr = baseaddr + rel->r_addend;
 112 #else
 113                         /* Address relative to the base address. */
 114                         *newaddr += baseaddr;
 115 #endif
 116                         break;
 117                 default:
 118                         /* XXX: do we need other relocations ? */
 119                         break;
 120                 }
 121                 rel = (ElfW_Rel *)(void *)((caddr_t) rel + relent);
 122         }
 123 }