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