arch/mips/kernel/module-rela.c

   1 /*
   2  *  This program is free software; you can redistribute it and/or modify
   3  *  it under the terms of the GNU General Public License as published by
   4  *  the Free Software Foundation; either version 2 of the License, or
   5  *  (at your option) any later version.
   6  *
   7  *  This program is distributed in the hope that it will be useful,
   8  *  but WITHOUT ANY WARRANTY; without even the implied warranty of
   9  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  10  *  GNU General Public License for more details.
  11  *
  12  *  You should have received a copy of the GNU General Public License
  13  *  along with this program; if not, write to the Free Software
  14  *  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
  15  *
  16  *  Copyright (C) 2001 Rusty Russell.
  17  *  Copyright (C) 2003, 2004 Ralf Baechle (ralf@linux-mips.org)
  18  *  Copyright (C) 2005 Thiemo Seufer
  19  */
  20
  21 #include <linux/elf.h>
  22 #include <linux/err.h>
  23 #include <linux/errno.h>
  24 #include <linux/moduleloader.h>
  25
  26 extern int apply_r_mips_none(struct module *me, u32 *location, Elf_Addr v);
  27
  28 static int apply_r_mips_32_rela(struct module *me, u32 *location, Elf_Addr v)
  29 {
  30         *location = v;
  31
  32         return 0;
  33 }
  34
  35 static int apply_r_mips_26_rela(struct module *me, u32 *location, Elf_Addr v)
  36 {
  37         if (v % 4) {
  38                 pr_err("module %s: dangerous R_MIPS_26 RELArelocation\n",
  39                        me->name);
  40                 return -ENOEXEC;
  41         }
  42
  43         if ((v & 0xf0000000) != (((unsigned long)location + 4) & 0xf0000000)) {
  44                 printk(KERN_ERR
  45                        "module %s: relocation overflow\n",
  46                        me->name);
  47                 return -ENOEXEC;
  48         }
  49
  50         *location = (*location & ~0x03ffffff) | ((v >> 2) & 0x03ffffff);
  51
  52         return 0;
  53 }
  54
  55 static int apply_r_mips_hi16_rela(struct module *me, u32 *location, Elf_Addr v)
  56 {
  57         *location = (*location & 0xffff0000) |
  58                     ((((long long) v + 0x8000LL) >> 16) & 0xffff);
  59
  60         return 0;
  61 }
  62
  63 static int apply_r_mips_lo16_rela(struct module *me, u32 *location, Elf_Addr v)
  64 {
  65         *location = (*location & 0xffff0000) | (v & 0xffff);
  66
  67         return 0;
  68 }
  69
  70 static int apply_r_mips_64_rela(struct module *me, u32 *location, Elf_Addr v)
  71 {
  72         *(Elf_Addr *)location = v;
  73
  74         return 0;
  75 }
  76
  77 static int apply_r_mips_higher_rela(struct module *me, u32 *location,
  78                                     Elf_Addr v)
  79 {
  80         *location = (*location & 0xffff0000) |
  81                     ((((long long) v + 0x80008000LL) >> 32) & 0xffff);
  82
  83         return 0;
  84 }
  85
  86 static int apply_r_mips_highest_rela(struct module *me, u32 *location,
  87                                      Elf_Addr v)
  88 {
  89         *location = (*location & 0xffff0000) |
  90                     ((((long long) v + 0x800080008000LL) >> 48) & 0xffff);
  91
  92         return 0;
  93 }
  94
  95 static int (*reloc_handlers_rela[]) (struct module *me, u32 *location,
  96                                 Elf_Addr v) = {
  97         [R_MIPS_NONE]           = apply_r_mips_none,
  98         [R_MIPS_32]             = apply_r_mips_32_rela,
  99         [R_MIPS_26]             = apply_r_mips_26_rela,
 100         [R_MIPS_HI16]           = apply_r_mips_hi16_rela,
 101         [R_MIPS_LO16]           = apply_r_mips_lo16_rela,
 102         [R_MIPS_64]             = apply_r_mips_64_rela,
 103         [R_MIPS_HIGHER]         = apply_r_mips_higher_rela,
 104         [R_MIPS_HIGHEST]        = apply_r_mips_highest_rela
 105 };
 106
 107 int apply_relocate_add(Elf_Shdr *sechdrs, const char *strtab,
 108                        unsigned int symindex, unsigned int relsec,
 109                        struct module *me)
 110 {
 111         Elf_Mips_Rela *rel = (void *) sechdrs[relsec].sh_addr;
 112         Elf_Sym *sym;
 113         u32 *location;
 114         unsigned int i;
 115         Elf_Addr v;
 116         int res;
 117
 118         pr_debug("Applying relocate section %u to %u\n", relsec,
 119                sechdrs[relsec].sh_info);
 120
 121         for (i = 0; i < sechdrs[relsec].sh_size / sizeof(*rel); i++) {
 122                 /* This is where to make the change */
 123                 location = (void *)sechdrs[sechdrs[relsec].sh_info].sh_addr
 124                         + rel[i].r_offset;
 125                 /* This is the symbol it is referring to */
 126                 sym = (Elf_Sym *)sechdrs[symindex].sh_addr
 127                         + ELF_MIPS_R_SYM(rel[i]);
 128                 if (IS_ERR_VALUE(sym->st_value)) {
 129                         /* Ignore unresolved weak symbol */
 130                         if (ELF_ST_BIND(sym->st_info) == STB_WEAK)
 131                                 continue;
 132                         printk(KERN_WARNING "%s: Unknown symbol %s\n",
 133                                me->name, strtab + sym->st_name);
 134                         return -ENOENT;
 135                 }
 136
 137                 v = sym->st_value + rel[i].r_addend;
 138
 139                 res = reloc_handlers_rela[ELF_MIPS_R_TYPE(rel[i])](me, location, v);
 140                 if (res)
 141                         return res;
 142         }
 143
 144         return 0;
 145 }