arch/x86/kernel/module_32.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 #include <linux/bug.h>
  25
  26 #if 0
  27 #define DEBUGP printk
  28 #else
  29 #define DEBUGP(fmt...)
  30 #endif
  31
  32 void *module_alloc(unsigned long size)
  33 {
  34         if (size == 0)
  35                 return NULL;
  36         return vmalloc_exec(size);
  37 }
  38
  39
  40 /* Free memory returned from module_alloc */
  41 void module_free(struct module *mod, void *module_region)
  42 {
  43         vfree(module_region);
  44         /* FIXME: If module_region == mod->init_region, trim exception
  45            table entries. */
  46 }
  47
  48 /* We don't need anything special. */
  49 int module_frob_arch_sections(Elf_Ehdr *hdr,
  50                               Elf_Shdr *sechdrs,
  51                               char *secstrings,
  52                               struct module *mod)
  53 {
  54         return 0;
  55 }
  56
  57 int apply_relocate(Elf32_Shdr *sechdrs,
  58                    const char *strtab,
  59                    unsigned int symindex,
  60                    unsigned int relsec,
  61                    struct module *me)
  62 {
  63         unsigned int i;
  64         Elf32_Rel *rel = (void *)sechdrs[relsec].sh_addr;
  65         Elf32_Sym *sym;
  66         uint32_t *location;
  67
  68         DEBUGP("Applying relocate section %u to %u\n", relsec,
  69                sechdrs[relsec].sh_info);
  70         for (i = 0; i < sechdrs[relsec].sh_size / sizeof(*rel); i++) {
  71                 /* This is where to make the change */
  72                 location = (void *)sechdrs[sechdrs[relsec].sh_info].sh_addr
  73                         + rel[i].r_offset;
  74                 /* This is the symbol it is referring to.  Note that all
  75                    undefined symbols have been resolved.  */
  76                 sym = (Elf32_Sym *)sechdrs[symindex].sh_addr
  77                         + ELF32_R_SYM(rel[i].r_info);
  78
  79                 switch (ELF32_R_TYPE(rel[i].r_info)) {
  80                 case R_386_32:
  81                         /* We add the value into the location given */
  82                         *location += sym->st_value;
  83                         break;
  84                 case R_386_PC32:
  85                         /* Add the value, subtract its postition */
  86                         *location += sym->st_value - (uint32_t)location;
  87                         break;
  88                 default:
  89                         printk(KERN_ERR "module %s: Unknown relocation: %u\n",
  90                                me->name, ELF32_R_TYPE(rel[i].r_info));
  91                         return -ENOEXEC;
  92                 }
  93         }
  94         return 0;
  95 }
  96
  97 int apply_relocate_add(Elf32_Shdr *sechdrs,
  98                        const char *strtab,
  99                        unsigned int symindex,
 100                        unsigned int relsec,
 101                        struct module *me)
 102 {
 103         printk(KERN_ERR "module %s: ADD RELOCATION unsupported\n",
 104                me->name);
 105         return -ENOEXEC;
 106 }
 107
 108 int module_finalize(const Elf_Ehdr *hdr,
 109                     const Elf_Shdr *sechdrs,
 110                     struct module *me)
 111 {
 112         const Elf_Shdr *s, *text = NULL, *alt = NULL, *locks = NULL,
 113                 *para = NULL;
 114         char *secstrings = (void *)hdr + sechdrs[hdr->e_shstrndx].sh_offset;
 115
 116         for (s = sechdrs; s < sechdrs + hdr->e_shnum; s++) {
 117                 if (!strcmp(".text", secstrings + s->sh_name))
 118                         text = s;
 119                 if (!strcmp(".altinstructions", secstrings + s->sh_name))
 120                         alt = s;
 121                 if (!strcmp(".smp_locks", secstrings + s->sh_name))
 122                         locks = s;
 123                 if (!strcmp(".parainstructions", secstrings + s->sh_name))
 124                         para = s;
 125         }
 126
 127         if (alt) {
 128                 /* patch .altinstructions */
 129                 void *aseg = (void *)alt->sh_addr;
 130                 apply_alternatives(aseg, aseg + alt->sh_size);
 131         }
 132         if (locks && text) {
 133                 void *lseg = (void *)locks->sh_addr;
 134                 void *tseg = (void *)text->sh_addr;
 135                 alternatives_smp_module_add(me, me->name,
 136                                             lseg, lseg + locks->sh_size,
 137                                             tseg, tseg + text->sh_size);
 138         }
 139
 140         if (para) {
 141                 void *pseg = (void *)para->sh_addr;
 142                 apply_paravirt(pseg, pseg + para->sh_size);
 143         }
 144
 145         return module_bug_finalize(hdr, sechdrs, me);
 146 }
 147
 148 void module_arch_cleanup(struct module *mod)
 149 {
 150         alternatives_smp_module_del(mod);
 151         module_bug_cleanup(mod);
 152 }