arch/i386/kernel/module.c

   1 /*  Kernel module help for i386.
   2     Copyright (C) 2001 Rusty Russell.
   3
   4     This program is free software; you can redistribute it and/or modify
   5     it under the terms of the GNU General Public License as published by
   6     the Free Software Foundation; either version 2 of the License, or
   7     (at your option) any later version.
   8
   9     This program is distributed in the hope that it will be useful,
  10     but WITHOUT ANY WARRANTY; without even the implied warranty of
  11     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12     GNU General Public License for more details.
  13
  14     You should have received a copy of the GNU General Public License
  15     along with this program; if not, write to the Free Software
  16     Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
  17 */
  18 #include <linux/moduleloader.h>
  19 #include <linux/elf.h>
  20 #include <linux/vmalloc.h>
  21 #include <linux/fs.h>
  22 #include <linux/string.h>
  23 #include <linux/kernel.h>
  24
  25 #if 0
  26 #define DEBUGP printk
  27 #else
  28 #define DEBUGP(fmt...)
  29 #endif
  30
  31 void *module_alloc(unsigned long size)
  32 {
  33         if (size == 0)
  34                 return NULL;
  35         return vmalloc_exec(size);
  36 }
  37
  38
  39 /* Free memory returned from module_alloc */
  40 void module_free(struct module *mod, void *module_region)
  41 {
  42         vfree(module_region);
  43         /* FIXME: If module_region == mod->init_region, trim exception
  44            table entries. */
  45 }
  46
  47 /* We don't need anything special. */
  48 int module_frob_arch_sections(Elf_Ehdr *hdr,
  49                               Elf_Shdr *sechdrs,
  50                               char *secstrings,
  51                               struct module *mod)
  52 {
  53         return 0;
  54 }
  55
  56 int apply_relocate(Elf32_Shdr *sechdrs,
  57                    const char *strtab,
  58                    unsigned int symindex,
  59                    unsigned int relsec,
  60                    struct module *me)
  61 {
  62         unsigned int i;
  63         Elf32_Rel *rel = (void *)sechdrs[relsec].sh_addr;
  64         Elf32_Sym *sym;
  65         uint32_t *location;
  66
  67         DEBUGP("Applying relocate section %u to %u\n", relsec,
  68                sechdrs[relsec].sh_info);
  69         for (i = 0; i < sechdrs[relsec].sh_size / sizeof(*rel); i++) {
  70                 /* This is where to make the change */
  71                 location = (void *)sechdrs[sechdrs[relsec].sh_info].sh_addr
  72                         + rel[i].r_offset;
  73                 /* This is the symbol it is referring to.  Note that all
  74                    undefined symbols have been resolved.  */
  75                 sym = (Elf32_Sym *)sechdrs[symindex].sh_addr
  76                         + ELF32_R_SYM(rel[i].r_info);
  77
  78                 switch (ELF32_R_TYPE(rel[i].r_info)) {
  79                 case R_386_32:
  80                         /* We add the value into the location given */
  81                         *location += sym->st_value;
  82                         break;
  83                 case R_386_PC32:
  84                         /* Add the value, subtract its postition */
  85                         *location += sym->st_value - (uint32_t)location;
  86                         break;
  87                 default:
  88                         printk(KERN_ERR "module %s: Unknown relocation: %u\n",
  89                                me->name, ELF32_R_TYPE(rel[i].r_info));
  90                         return -ENOEXEC;
  91                 }
  92         }
  93         return 0;
  94 }
  95
  96 int apply_relocate_add(Elf32_Shdr *sechdrs,
  97                        const char *strtab,
  98                        unsigned int symindex,
  99                        unsigned int relsec,
 100                        struct module *me)
 101 {
 102         printk(KERN_ERR "module %s: ADD RELOCATION unsupported\n",
 103                me->name);
 104         return -ENOEXEC;
 105 }
 106
 107 extern void apply_alternatives(void *start, void *end);
 108
 109 int module_finalize(const Elf_Ehdr *hdr,
 110                     const Elf_Shdr *sechdrs,
 111                     struct module *me)
 112 {
 113         const Elf_Shdr *s;
 114         char *secstrings = (void *)hdr + sechdrs[hdr->e_shstrndx].sh_offset;
 115
 116         /* look for .altinstructions to patch */
 117         for (s = sechdrs; s < sechdrs + hdr->e_shnum; s++) {
 118                 void *seg;
 119                 if (strcmp(".altinstructions", secstrings + s->sh_name))
 120                         continue;
 121                 seg = (void *)s->sh_addr;
 122                 apply_alternatives(seg, seg + s->sh_size);
 123         }
 124         return 0;
 125 }
 126
 127 void module_arch_cleanup(struct module *mod)
 128 {
 129 }