arch/mn10300/kernel/module.c

   1 /* MN10300 Kernel module helper routines
   2  *
   3  * Copyright (C) 2007, 2008, 2009 Red Hat, Inc. All Rights Reserved.
   4  * Written by Mark Salter (msalter@redhat.com)
   5  * - Derived from arch/i386/kernel/module.c
   6  *
   7  * This program is free software; you can redistribute it and/or modify
   8  * it under the terms of the GNU General Public Licence as published by
   9  * the Free Software Foundation; either version 2 of the Licence, or
  10  * (at your option) any later version.
  11  *
  12  * This program is distributed in the hope that it will be useful,
  13  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  14  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15  * GNU General Public Licence for more details.
  16  *
  17  * You should have received a copy of the GNU General Public Licence
  18  * along with this program; if not, write to the Free Software
  19  * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
  20  */
  21 #include <linux/moduleloader.h>
  22 #include <linux/elf.h>
  23 #include <linux/vmalloc.h>
  24 #include <linux/fs.h>
  25 #include <linux/string.h>
  26 #include <linux/kernel.h>
  27 #include <linux/bug.h>
  28
  29 #if 0
  30 #define DEBUGP printk
  31 #else
  32 #define DEBUGP(fmt, ...)
  33 #endif
  34
  35 static void reloc_put16(uint8_t *p, uint32_t val)
  36 {
  37         p[0] = val & 0xff;
  38         p[1] = (val >> 8) & 0xff;
  39 }
  40
  41 static void reloc_put24(uint8_t *p, uint32_t val)
  42 {
  43         reloc_put16(p, val);
  44         p[2] = (val >> 16) & 0xff;
  45 }
  46
  47 static void reloc_put32(uint8_t *p, uint32_t val)
  48 {
  49         reloc_put16(p, val);
  50         reloc_put16(p+2, val >> 16);
  51 }
  52
  53 /*
  54  * apply a RELA relocation
  55  */
  56 int apply_relocate_add(Elf32_Shdr *sechdrs,
  57                        const char *strtab,
  58                        unsigned int symindex,
  59                        unsigned int relsec,
  60                        struct module *me)
  61 {
  62         unsigned int i, sym_diff_seen = 0;
  63         Elf32_Rela *rel = (void *)sechdrs[relsec].sh_addr;
  64         Elf32_Sym *sym;
  65         Elf32_Addr relocation, sym_diff_val = 0;
  66         uint8_t *location;
  67         uint32_t value;
  68
  69         DEBUGP("Applying relocate section %u to %u\n",
  70                relsec, sechdrs[relsec].sh_info);
  71
  72         for (i = 0; i < sechdrs[relsec].sh_size / sizeof(*rel); i++) {
  73                 /* this is where to make the change */
  74                 location = (void *)sechdrs[sechdrs[relsec].sh_info].sh_addr
  75                         + rel[i].r_offset;
  76
  77                 /* this is the symbol the relocation is referring to (note that
  78                  * all undefined symbols have been resolved by the caller) */
  79                 sym = (Elf32_Sym *)sechdrs[symindex].sh_addr
  80                         + ELF32_R_SYM(rel[i].r_info);
  81
  82                 /* this is the adjustment to be made */
  83                 relocation = sym->st_value + rel[i].r_addend;
  84
  85                 if (sym_diff_seen) {
  86                         switch (ELF32_R_TYPE(rel[i].r_info)) {
  87                         case R_MN10300_32:
  88                         case R_MN10300_24:
  89                         case R_MN10300_16:
  90                         case R_MN10300_8:
  91                                 relocation -= sym_diff_val;
  92                                 sym_diff_seen = 0;
  93                                 break;
  94                         default:
  95                                 printk(KERN_ERR "module %s: Unexpected SYM_DIFF relocation: %u\n",
  96                                        me->name, ELF32_R_TYPE(rel[i].r_info));
  97                                 return -ENOEXEC;
  98                         }
  99                 }
 100
 101                 switch (ELF32_R_TYPE(rel[i].r_info)) {
 102                         /* for the first four relocation types, we simply
 103                          * store the adjustment at the location given */
 104                 case R_MN10300_32:
 105                         reloc_put32(location, relocation);
 106                         break;
 107                 case R_MN10300_24:
 108                         reloc_put24(location, relocation);
 109                         break;
 110                 case R_MN10300_16:
 111                         reloc_put16(location, relocation);
 112                         break;
 113                 case R_MN10300_8:
 114                         *location = relocation;
 115                         break;
 116
 117                         /* for the next three relocation types, we write the
 118                          * adjustment with the address subtracted over the
 119                          * value at the location given */
 120                 case R_MN10300_PCREL32:
 121                         value = relocation - (uint32_t) location;
 122                         reloc_put32(location, value);
 123                         break;
 124                 case R_MN10300_PCREL16:
 125                         value = relocation - (uint32_t) location;
 126                         reloc_put16(location, value);
 127                         break;
 128                 case R_MN10300_PCREL8:
 129                         *location = relocation - (uint32_t) location;
 130                         break;
 131
 132                 case R_MN10300_SYM_DIFF:
 133                         /* This is used to adjust the next reloc as required
 134                          * by relaxation. */
 135                         sym_diff_seen = 1;
 136                         sym_diff_val = sym->st_value;
 137                         break;
 138
 139                 case R_MN10300_ALIGN:
 140                         /* Just ignore the ALIGN relocs.
 141                          * Only interesting if kernel performed relaxation. */
 142                         continue;
 143
 144                 default:
 145                         printk(KERN_ERR "module %s: Unknown relocation: %u\n",
 146                                me->name, ELF32_R_TYPE(rel[i].r_info));
 147                         return -ENOEXEC;
 148                 }
 149         }
 150         if (sym_diff_seen) {
 151                 printk(KERN_ERR "module %s: Nothing follows SYM_DIFF relocation: %u\n",
 152                                        me->name, ELF32_R_TYPE(rel[i].r_info));
 153                 return -ENOEXEC;
 154         }
 155         return 0;
 156 }