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