LXR linux/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
  35static void reloc_put16(uint8_t *p, uint32_t val)
  36{
  37        p[0] = val & 0xff;
  38        p[1] = (val >> 8) & 0xff;
  39}
  40
  41static void reloc_put24(uint8_t *p, uint32_t val)
  42{
  43        reloc_put16(p, val);
  44        p[2] = (val >> 16) & 0xff;
  45}
  46
  47static 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 */
  56int 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}
 157