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