arch/x86/kernel/module.c

   1 /*  Kernel module help for x86.
   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 #include <linux/mm.h>
  26
  27 #include <asm/system.h>
  28 #include <asm/page.h>
  29 #include <asm/pgtable.h>
  30
  31 #if 0
  32 #define DEBUGP printk
  33 #else
  34 #define DEBUGP(fmt...)
  35 #endif
  36
  37 void *module_alloc(unsigned long size)
  38 {
  39         struct vm_struct *area;
  40
  41         if (!size)
  42                 return NULL;
  43         size = PAGE_ALIGN(size);
  44         if (size > MODULES_LEN)
  45                 return NULL;
  46
  47         area = __get_vm_area(size, VM_ALLOC, MODULES_VADDR, MODULES_END);
  48         if (!area)
  49                 return NULL;
  50
  51         return __vmalloc_area(area, GFP_KERNEL | __GFP_HIGHMEM,
  52                                         PAGE_KERNEL_EXEC);
  53 }
  54
  55 /* Free memory returned from module_alloc */
  56 void module_free(struct module *mod, void *module_region)
  57 {
  58         vfree(module_region);
  59         /* FIXME: If module_region == mod->init_region, trim exception
  60            table entries. */
  61 }
  62
  63 /* We don't need anything special. */
  64 int module_frob_arch_sections(Elf_Ehdr *hdr,
  65                               Elf_Shdr *sechdrs,
  66                               char *secstrings,
  67                               struct module *mod)
  68 {
  69         return 0;
  70 }
  71
  72 #ifdef CONFIG_X86_32
  73 int apply_relocate(Elf32_Shdr *sechdrs,
  74                    const char *strtab,
  75                    unsigned int symindex,
  76                    unsigned int relsec,
  77                    struct module *me)
  78 {
  79         unsigned int i;
  80         Elf32_Rel *rel = (void *)sechdrs[relsec].sh_addr;
  81         Elf32_Sym *sym;
  82         uint32_t *location;
  83
  84         DEBUGP("Applying relocate section %u to %u\n", relsec,
  85                sechdrs[relsec].sh_info);
  86         for (i = 0; i < sechdrs[relsec].sh_size / sizeof(*rel); i++) {
  87                 /* This is where to make the change */
  88                 location = (void *)sechdrs[sechdrs[relsec].sh_info].sh_addr
  89                         + rel[i].r_offset;
  90                 /* This is the symbol it is referring to.  Note that all
  91                    undefined symbols have been resolved.  */
  92                 sym = (Elf32_Sym *)sechdrs[symindex].sh_addr
  93                         + ELF32_R_SYM(rel[i].r_info);
  94
  95                 switch (ELF32_R_TYPE(rel[i].r_info)) {
  96                 case R_386_32:
  97                         /* We add the value into the location given */
  98                         *location += sym->st_value;
  99                         break;
 100                 case R_386_PC32:
 101                         /* Add the value, subtract its postition */
 102                         *location += sym->st_value - (uint32_t)location;
 103                         break;
 104                 default:
 105                         printk(KERN_ERR "module %s: Unknown relocation: %u\n",
 106                                me->name, ELF32_R_TYPE(rel[i].r_info));
 107                         return -ENOEXEC;
 108                 }
 109         }
 110         return 0;
 111 }
 112
 113 int apply_relocate_add(Elf32_Shdr *sechdrs,
 114                        const char *strtab,
 115                        unsigned int symindex,
 116                        unsigned int relsec,
 117                        struct module *me)
 118 {
 119         printk(KERN_ERR "module %s: ADD RELOCATION unsupported\n",
 120                me->name);
 121         return -ENOEXEC;
 122 }
 123 #else /*X86_64*/
 124 int apply_relocate_add(Elf64_Shdr *sechdrs,
 125                    const char *strtab,
 126                    unsigned int symindex,
 127                    unsigned int relsec,
 128                    struct module *me)
 129 {
 130         unsigned int i;
 131         Elf64_Rela *rel = (void *)sechdrs[relsec].sh_addr;
 132         Elf64_Sym *sym;
 133         void *loc;
 134         u64 val;
 135
 136         DEBUGP("Applying relocate section %u to %u\n", relsec,
 137                sechdrs[relsec].sh_info);
 138         for (i = 0; i < sechdrs[relsec].sh_size / sizeof(*rel); i++) {
 139                 /* This is where to make the change */
 140                 loc = (void *)sechdrs[sechdrs[relsec].sh_info].sh_addr
 141                         + rel[i].r_offset;
 142
 143                 /* This is the symbol it is referring to.  Note that all
 144                    undefined symbols have been resolved.  */
 145                 sym = (Elf64_Sym *)sechdrs[symindex].sh_addr
 146                         + ELF64_R_SYM(rel[i].r_info);
 147
 148                 DEBUGP("type %d st_value %Lx r_addend %Lx loc %Lx\n",
 149                         (int)ELF64_R_TYPE(rel[i].r_info),
 150                         sym->st_value, rel[i].r_addend, (u64)loc);
 151
 152                 val = sym->st_value + rel[i].r_addend;
 153
 154                 switch (ELF64_R_TYPE(rel[i].r_info)) {
 155                 case R_X86_64_NONE:
 156                         break;
 157                 case R_X86_64_64:
 158                         *(u64 *)loc = val;
 159                         break;
 160                 case R_X86_64_32:
 161                         *(u32 *)loc = val;
 162                         if (val != *(u32 *)loc)
 163                                 goto overflow;
 164                         break;
 165                 case R_X86_64_32S:
 166                         *(s32 *)loc = val;
 167                         if ((s64)val != *(s32 *)loc)
 168                                 goto overflow;
 169                         break;
 170                 case R_X86_64_PC32:
 171                         val -= (u64)loc;
 172                         *(u32 *)loc = val;
 173 #if 0
 174                         if ((s64)val != *(s32 *)loc)
 175                                 goto overflow;
 176 #endif
 177                         break;
 178                 default:
 179                         printk(KERN_ERR "module %s: Unknown rela relocation: %llu\n",
 180                                me->name, ELF64_R_TYPE(rel[i].r_info));
 181                         return -ENOEXEC;
 182                 }
 183         }
 184         return 0;
 185
 186 overflow:
 187         printk(KERN_ERR "overflow in relocation type %d val %Lx\n",
 188                (int)ELF64_R_TYPE(rel[i].r_info), val);
 189         printk(KERN_ERR "`%s' likely not compiled with -mcmodel=kernel\n",
 190                me->name);
 191         return -ENOEXEC;
 192 }
 193
 194 int apply_relocate(Elf_Shdr *sechdrs,
 195                    const char *strtab,
 196                    unsigned int symindex,
 197                    unsigned int relsec,
 198                    struct module *me)
 199 {
 200         printk(KERN_ERR "non add relocation not supported\n");
 201         return -ENOSYS;
 202 }
 203
 204 #endif
 205
 206 int module_finalize(const Elf_Ehdr *hdr,
 207                     const Elf_Shdr *sechdrs,
 208                     struct module *me)
 209 {
 210         const Elf_Shdr *s, *text = NULL, *alt = NULL, *locks = NULL,
 211                 *para = NULL;
 212         char *secstrings = (void *)hdr + sechdrs[hdr->e_shstrndx].sh_offset;
 213
 214         for (s = sechdrs; s < sechdrs + hdr->e_shnum; s++) {
 215                 if (!strcmp(".text", secstrings + s->sh_name))
 216                         text = s;
 217                 if (!strcmp(".altinstructions", secstrings + s->sh_name))
 218                         alt = s;
 219                 if (!strcmp(".smp_locks", secstrings + s->sh_name))
 220                         locks = s;
 221                 if (!strcmp(".parainstructions", secstrings + s->sh_name))
 222                         para = s;
 223         }
 224
 225         if (alt) {
 226                 /* patch .altinstructions */
 227                 void *aseg = (void *)alt->sh_addr;
 228                 apply_alternatives(aseg, aseg + alt->sh_size);
 229         }
 230         if (locks && text) {
 231                 void *lseg = (void *)locks->sh_addr;
 232                 void *tseg = (void *)text->sh_addr;
 233                 alternatives_smp_module_add(me, me->name,
 234                                             lseg, lseg + locks->sh_size,
 235                                             tseg, tseg + text->sh_size);
 236         }
 237
 238         if (para) {
 239                 void *pseg = (void *)para->sh_addr;
 240                 apply_paravirt(pseg, pseg + para->sh_size);
 241         }
 242
 243         return module_bug_finalize(hdr, sechdrs, me);
 244 }
 245
 246 void module_arch_cleanup(struct module *mod)
 247 {
 248         alternatives_smp_module_del(mod);
 249         module_bug_cleanup(mod);
 250 }