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/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 #ifdef CONFIG_X86_32
  48 int apply_relocate(Elf32_Shdr *sechdrs,
  49                    const char *strtab,
  50                    unsigned int symindex,
  51                    unsigned int relsec,
  52                    struct module *me)
  53 {
  54         unsigned int i;
  55         Elf32_Rel *rel = (void *)sechdrs[relsec].sh_addr;
  56         Elf32_Sym *sym;
  57         uint32_t *location;
  58
  59         DEBUGP("Applying relocate section %u to %u\n", relsec,
  60                sechdrs[relsec].sh_info);
  61         for (i = 0; i < sechdrs[relsec].sh_size / sizeof(*rel); i++) {
  62                 /* This is where to make the change */
  63                 location = (void *)sechdrs[sechdrs[relsec].sh_info].sh_addr
  64                         + rel[i].r_offset;
  65                 /* This is the symbol it is referring to.  Note that all
  66                    undefined symbols have been resolved.  */
  67                 sym = (Elf32_Sym *)sechdrs[symindex].sh_addr
  68                         + ELF32_R_SYM(rel[i].r_info);
  69
  70                 switch (ELF32_R_TYPE(rel[i].r_info)) {
  71                 case R_386_32:
  72                         /* We add the value into the location given */
  73                         *location += sym->st_value;
  74                         break;
  75                 case R_386_PC32:
  76                         /* Add the value, subtract its postition */
  77                         *location += sym->st_value - (uint32_t)location;
  78                         break;
  79                 default:
  80                         printk(KERN_ERR "module %s: Unknown relocation: %u\n",
  81                                me->name, ELF32_R_TYPE(rel[i].r_info));
  82                         return -ENOEXEC;
  83                 }
  84         }
  85         return 0;
  86 }
  87 #else /*X86_64*/
  88 int apply_relocate_add(Elf64_Shdr *sechdrs,
  89                    const char *strtab,
  90                    unsigned int symindex,
  91                    unsigned int relsec,
  92                    struct module *me)
  93 {
  94         unsigned int i;
  95         Elf64_Rela *rel = (void *)sechdrs[relsec].sh_addr;
  96         Elf64_Sym *sym;
  97         void *loc;
  98         u64 val;
  99
 100         DEBUGP("Applying relocate section %u to %u\n", relsec,
 101                sechdrs[relsec].sh_info);
 102         for (i = 0; i < sechdrs[relsec].sh_size / sizeof(*rel); i++) {
 103                 /* This is where to make the change */
 104                 loc = (void *)sechdrs[sechdrs[relsec].sh_info].sh_addr
 105                         + rel[i].r_offset;
 106
 107                 /* This is the symbol it is referring to.  Note that all
 108                    undefined symbols have been resolved.  */
 109                 sym = (Elf64_Sym *)sechdrs[symindex].sh_addr
 110                         + ELF64_R_SYM(rel[i].r_info);
 111
 112                 DEBUGP("type %d st_value %Lx r_addend %Lx loc %Lx\n",
 113                         (int)ELF64_R_TYPE(rel[i].r_info),
 114                         sym->st_value, rel[i].r_addend, (u64)loc);
 115
 116                 val = sym->st_value + rel[i].r_addend;
 117
 118                 switch (ELF64_R_TYPE(rel[i].r_info)) {
 119                 case R_X86_64_NONE:
 120                         break;
 121                 case R_X86_64_64:
 122                         *(u64 *)loc = val;
 123                         break;
 124                 case R_X86_64_32:
 125                         *(u32 *)loc = val;
 126                         if (val != *(u32 *)loc)
 127                                 goto overflow;
 128                         break;
 129                 case R_X86_64_32S:
 130                         *(s32 *)loc = val;
 131                         if ((s64)val != *(s32 *)loc)
 132                                 goto overflow;
 133                         break;
 134                 case R_X86_64_PC32:
 135                         val -= (u64)loc;
 136                         *(u32 *)loc = val;
 137 #if 0
 138                         if ((s64)val != *(s32 *)loc)
 139                                 goto overflow;
 140 #endif
 141                         break;
 142                 default:
 143                         printk(KERN_ERR "module %s: Unknown rela relocation: %llu\n",
 144                                me->name, ELF64_R_TYPE(rel[i].r_info));
 145                         return -ENOEXEC;
 146                 }
 147         }
 148         return 0;
 149
 150 overflow:
 151         printk(KERN_ERR "overflow in relocation type %d val %Lx\n",
 152                (int)ELF64_R_TYPE(rel[i].r_info), val);
 153         printk(KERN_ERR "`%s' likely not compiled with -mcmodel=kernel\n",
 154                me->name);
 155         return -ENOEXEC;
 156 }
 157 #endif
 158
 159 int module_finalize(const Elf_Ehdr *hdr,
 160                     const Elf_Shdr *sechdrs,
 161                     struct module *me)
 162 {
 163         const Elf_Shdr *s, *text = NULL, *alt = NULL, *locks = NULL,
 164                 *para = NULL;
 165         char *secstrings = (void *)hdr + sechdrs[hdr->e_shstrndx].sh_offset;
 166
 167         for (s = sechdrs; s < sechdrs + hdr->e_shnum; s++) {
 168                 if (!strcmp(".text", secstrings + s->sh_name))
 169                         text = s;
 170                 if (!strcmp(".altinstructions", secstrings + s->sh_name))
 171                         alt = s;
 172                 if (!strcmp(".smp_locks", secstrings + s->sh_name))
 173                         locks = s;
 174                 if (!strcmp(".parainstructions", secstrings + s->sh_name))
 175                         para = s;
 176         }
 177
 178         if (alt) {
 179                 /* patch .altinstructions */
 180                 void *aseg = (void *)alt->sh_addr;
 181                 apply_alternatives(aseg, aseg + alt->sh_size);
 182         }
 183         if (locks && text) {
 184                 void *lseg = (void *)locks->sh_addr;
 185                 void *tseg = (void *)text->sh_addr;
 186                 alternatives_smp_module_add(me, me->name,
 187                                             lseg, lseg + locks->sh_size,
 188                                             tseg, tseg + text->sh_size);
 189         }
 190
 191         if (para) {
 192                 void *pseg = (void *)para->sh_addr;
 193                 apply_paravirt(pseg, pseg + para->sh_size);
 194         }
 195
 196         /* make jump label nops */
 197         jump_label_apply_nops(me);
 198
 199         return 0;
 200 }
 201
 202 void module_arch_cleanup(struct module *mod)
 203 {
 204         alternatives_smp_module_del(mod);
 205 }