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         struct vm_struct *area;
  41
  42         if (!size)
  43                 return NULL;
  44         size = PAGE_ALIGN(size);
  45         if (size > MODULES_LEN)
  46                 return NULL;
  47
  48         area = __get_vm_area(size, VM_ALLOC, MODULES_VADDR, MODULES_END);
  49         if (!area)
  50                 return NULL;
  51
  52         return __vmalloc_area(area, GFP_KERNEL | __GFP_HIGHMEM,
  53                                         PAGE_KERNEL_EXEC);
  54 }
  55
  56 /* Free memory returned from module_alloc */
  57 void module_free(struct module *mod, void *module_region)
  58 {
  59         vfree(module_region);
  60 }
  61
  62 /* We don't need anything special. */
  63 int module_frob_arch_sections(Elf_Ehdr *hdr,
  64                               Elf_Shdr *sechdrs,
  65                               char *secstrings,
  66                               struct module *mod)
  67 {
  68         return 0;
  69 }
  70
  71 #ifdef CONFIG_X86_32
  72 int apply_relocate(Elf32_Shdr *sechdrs,
  73                    const char *strtab,
  74                    unsigned int symindex,
  75                    unsigned int relsec,
  76                    struct module *me)
  77 {
  78         unsigned int i;
  79         Elf32_Rel *rel = (void *)sechdrs[relsec].sh_addr;
  80         Elf32_Sym *sym;
  81         uint32_t *location;
  82
  83         DEBUGP("Applying relocate section %u to %u\n", relsec,
  84                sechdrs[relsec].sh_info);
  85         for (i = 0; i < sechdrs[relsec].sh_size / sizeof(*rel); i++) {
  86                 /* This is where to make the change */
  87                 location = (void *)sechdrs[sechdrs[relsec].sh_info].sh_addr
  88                         + rel[i].r_offset;
  89                 /* This is the symbol it is referring to.  Note that all
  90                    undefined symbols have been resolved.  */
  91                 sym = (Elf32_Sym *)sechdrs[symindex].sh_addr
  92                         + ELF32_R_SYM(rel[i].r_info);
  93
  94                 switch (ELF32_R_TYPE(rel[i].r_info)) {
  95                 case R_386_32:
  96                         /* We add the value into the location given */
  97                         *location += sym->st_value;
  98                         break;
  99                 case R_386_PC32:
 100                         /* Add the value, subtract its postition */
 101                         *location += sym->st_value - (uint32_t)location;
 102                         break;
 103                 default:
 104                         printk(KERN_ERR "module %s: Unknown relocation: %u\n",
 105                                me->name, ELF32_R_TYPE(rel[i].r_info));
 106                         return -ENOEXEC;
 107                 }
 108         }
 109         return 0;
 110 }
 111
 112 int apply_relocate_add(Elf32_Shdr *sechdrs,
 113                        const char *strtab,
 114                        unsigned int symindex,
 115                        unsigned int relsec,
 116                        struct module *me)
 117 {
 118         printk(KERN_ERR "module %s: ADD RELOCATION unsupported\n",
 119                me->name);
 120         return -ENOEXEC;
 121 }
 122 #else /*X86_64*/
 123 int apply_relocate_add(Elf64_Shdr *sechdrs,
 124                    const char *strtab,
 125                    unsigned int symindex,
 126                    unsigned int relsec,
 127                    struct module *me)
 128 {
 129         unsigned int i;
 130         Elf64_Rela *rel = (void *)sechdrs[relsec].sh_addr;
 131         Elf64_Sym *sym;
 132         void *loc;
 133         u64 val;
 134
 135         DEBUGP("Applying relocate section %u to %u\n", relsec,
 136                sechdrs[relsec].sh_info);
 137         for (i = 0; i < sechdrs[relsec].sh_size / sizeof(*rel); i++) {
 138                 /* This is where to make the change */
 139                 loc = (void *)sechdrs[sechdrs[relsec].sh_info].sh_addr
 140                         + rel[i].r_offset;
 141
 142                 /* This is the symbol it is referring to.  Note that all
 143                    undefined symbols have been resolved.  */
 144                 sym = (Elf64_Sym *)sechdrs[symindex].sh_addr
 145                         + ELF64_R_SYM(rel[i].r_info);
 146
 147                 DEBUGP("type %d st_value %Lx r_addend %Lx loc %Lx\n",
 148                         (int)ELF64_R_TYPE(rel[i].r_info),
 149                         sym->st_value, rel[i].r_addend, (u64)loc);
 150
 151                 val = sym->st_value + rel[i].r_addend;
 152
 153                 switch (ELF64_R_TYPE(rel[i].r_info)) {
 154                 case R_X86_64_NONE:
 155                         break;
 156                 case R_X86_64_64:
 157                         *(u64 *)loc = val;
 158                         break;
 159                 case R_X86_64_32:
 160                         *(u32 *)loc = val;
 161                         if (val != *(u32 *)loc)
 162                                 goto overflow;
 163                         break;
 164                 case R_X86_64_32S:
 165                         *(s32 *)loc = val;
 166                         if ((s64)val != *(s32 *)loc)
 167                                 goto overflow;
 168                         break;
 169                 case R_X86_64_PC32:
 170                         val -= (u64)loc;
 171                         *(u32 *)loc = val;
 172 #if 0
 173                         if ((s64)val != *(s32 *)loc)
 174                                 goto overflow;
 175 #endif
 176                         break;
 177                 default:
 178                         printk(KERN_ERR "module %s: Unknown rela relocation: %llu\n",
 179                                me->name, ELF64_R_TYPE(rel[i].r_info));
 180                         return -ENOEXEC;
 181                 }
 182         }
 183         return 0;
 184
 185 overflow:
 186         printk(KERN_ERR "overflow in relocation type %d val %Lx\n",
 187                (int)ELF64_R_TYPE(rel[i].r_info), val);
 188         printk(KERN_ERR "`%s' likely not compiled with -mcmodel=kernel\n",
 189                me->name);
 190         return -ENOEXEC;
 191 }
 192
 193 int apply_relocate(Elf_Shdr *sechdrs,
 194                    const char *strtab,
 195                    unsigned int symindex,
 196                    unsigned int relsec,
 197                    struct module *me)
 198 {
 199         printk(KERN_ERR "non add relocation not supported\n");
 200         return -ENOSYS;
 201 }
 202
 203 #endif
 204
 205 int module_finalize(const Elf_Ehdr *hdr,
 206                     const Elf_Shdr *sechdrs,
 207                     struct module *me)
 208 {
 209         const Elf_Shdr *s, *text = NULL, *alt = NULL, *locks = NULL,
 210                 *para = NULL;
 211         char *secstrings = (void *)hdr + sechdrs[hdr->e_shstrndx].sh_offset;
 212
 213         for (s = sechdrs; s < sechdrs + hdr->e_shnum; s++) {
 214                 if (!strcmp(".text", secstrings + s->sh_name))
 215                         text = s;
 216                 if (!strcmp(".altinstructions", secstrings + s->sh_name))
 217                         alt = s;
 218                 if (!strcmp(".smp_locks", secstrings + s->sh_name))
 219                         locks = s;
 220                 if (!strcmp(".parainstructions", secstrings + s->sh_name))
 221                         para = s;
 222         }
 223
 224         if (alt) {
 225                 /* patch .altinstructions */
 226                 void *aseg = (void *)alt->sh_addr;
 227                 apply_alternatives(aseg, aseg + alt->sh_size);
 228         }
 229         if (locks && text) {
 230                 void *lseg = (void *)locks->sh_addr;
 231                 void *tseg = (void *)text->sh_addr;
 232                 alternatives_smp_module_add(me, me->name,
 233                                             lseg, lseg + locks->sh_size,
 234                                             tseg, tseg + text->sh_size);
 235         }
 236
 237         if (para) {
 238                 void *pseg = (void *)para->sh_addr;
 239                 apply_paravirt(pseg, pseg + para->sh_size);
 240         }
 241
 242         /* make jump label nops */
 243         jump_label_apply_nops(me);
 244
 245         return 0;
 246 }
 247
 248 void module_arch_cleanup(struct module *mod)
 249 {
 250         alternatives_smp_module_del(mod);
 251 }