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 #ifdef CONFIG_X86_32
  49 int apply_relocate(Elf32_Shdr *sechdrs,
  50                    const char *strtab,
  51                    unsigned int symindex,
  52                    unsigned int relsec,
  53                    struct module *me)
  54 {
  55         unsigned int i;
  56         Elf32_Rel *rel = (void *)sechdrs[relsec].sh_addr;
  57         Elf32_Sym *sym;
  58         uint32_t *location;
  59
  60         DEBUGP("Applying relocate section %u to %u\n", relsec,
  61                sechdrs[relsec].sh_info);
  62         for (i = 0; i < sechdrs[relsec].sh_size / sizeof(*rel); i++) {
  63                 /* This is where to make the change */
  64                 location = (void *)sechdrs[sechdrs[relsec].sh_info].sh_addr
  65                         + rel[i].r_offset;
  66                 /* This is the symbol it is referring to.  Note that all
  67                    undefined symbols have been resolved.  */
  68                 sym = (Elf32_Sym *)sechdrs[symindex].sh_addr
  69                         + ELF32_R_SYM(rel[i].r_info);
  70
  71                 switch (ELF32_R_TYPE(rel[i].r_info)) {
  72                 case R_386_32:
  73                         /* We add the value into the location given */
  74                         *location += sym->st_value;
  75                         break;
  76                 case R_386_PC32:
  77                         /* Add the value, subtract its postition */
  78                         *location += sym->st_value - (uint32_t)location;
  79                         break;
  80                 default:
  81                         printk(KERN_ERR "module %s: Unknown relocation: %u\n",
  82                                me->name, ELF32_R_TYPE(rel[i].r_info));
  83                         return -ENOEXEC;
  84                 }
  85         }
  86         return 0;
  87 }
  88 #else /*X86_64*/
  89 int apply_relocate_add(Elf64_Shdr *sechdrs,
  90                    const char *strtab,
  91                    unsigned int symindex,
  92                    unsigned int relsec,
  93                    struct module *me)
  94 {
  95         unsigned int i;
  96         Elf64_Rela *rel = (void *)sechdrs[relsec].sh_addr;
  97         Elf64_Sym *sym;
  98         void *loc;
  99         u64 val;
 100
 101         DEBUGP("Applying relocate section %u to %u\n", relsec,
 102                sechdrs[relsec].sh_info);
 103         for (i = 0; i < sechdrs[relsec].sh_size / sizeof(*rel); i++) {
 104                 /* This is where to make the change */
 105                 loc = (void *)sechdrs[sechdrs[relsec].sh_info].sh_addr
 106                         + rel[i].r_offset;
 107
 108                 /* This is the symbol it is referring to.  Note that all
 109                    undefined symbols have been resolved.  */
 110                 sym = (Elf64_Sym *)sechdrs[symindex].sh_addr
 111                         + ELF64_R_SYM(rel[i].r_info);
 112
 113                 DEBUGP("type %d st_value %Lx r_addend %Lx loc %Lx\n",
 114                         (int)ELF64_R_TYPE(rel[i].r_info),
 115                         sym->st_value, rel[i].r_addend, (u64)loc);
 116
 117                 val = sym->st_value + rel[i].r_addend;
 118
 119                 switch (ELF64_R_TYPE(rel[i].r_info)) {
 120                 case R_X86_64_NONE:
 121                         break;
 122                 case R_X86_64_64:
 123                         *(u64 *)loc = val;
 124                         break;
 125                 case R_X86_64_32:
 126                         *(u32 *)loc = val;
 127                         if (val != *(u32 *)loc)
 128                                 goto overflow;
 129                         break;
 130                 case R_X86_64_32S:
 131                         *(s32 *)loc = val;
 132                         if ((s64)val != *(s32 *)loc)
 133                                 goto overflow;
 134                         break;
 135                 case R_X86_64_PC32:
 136                         val -= (u64)loc;
 137                         *(u32 *)loc = val;
 138 #if 0
 139                         if ((s64)val != *(s32 *)loc)
 140                                 goto overflow;
 141 #endif
 142                         break;
 143                 default:
 144                         printk(KERN_ERR "module %s: Unknown rela relocation: %llu\n",
 145                                me->name, ELF64_R_TYPE(rel[i].r_info));
 146                         return -ENOEXEC;
 147                 }
 148         }
 149         return 0;
 150
 151 overflow:
 152         printk(KERN_ERR "overflow in relocation type %d val %Lx\n",
 153                (int)ELF64_R_TYPE(rel[i].r_info), val);
 154         printk(KERN_ERR "`%s' likely not compiled with -mcmodel=kernel\n",
 155                me->name);
 156         return -ENOEXEC;
 157 }
 158 #endif
 159
 160 int module_finalize(const Elf_Ehdr *hdr,
 161                     const Elf_Shdr *sechdrs,
 162                     struct module *me)
 163 {
 164         const Elf_Shdr *s, *text = NULL, *alt = NULL, *locks = NULL,
 165                 *para = NULL;
 166         char *secstrings = (void *)hdr + sechdrs[hdr->e_shstrndx].sh_offset;
 167
 168         for (s = sechdrs; s < sechdrs + hdr->e_shnum; s++) {
 169                 if (!strcmp(".text", secstrings + s->sh_name))
 170                         text = s;
 171                 if (!strcmp(".altinstructions", secstrings + s->sh_name))
 172                         alt = s;
 173                 if (!strcmp(".smp_locks", secstrings + s->sh_name))
 174                         locks = s;
 175                 if (!strcmp(".parainstructions", secstrings + s->sh_name))
 176                         para = s;
 177         }
 178
 179         if (alt) {
 180                 /* patch .altinstructions */
 181                 void *aseg = (void *)alt->sh_addr;
 182                 apply_alternatives(aseg, aseg + alt->sh_size);
 183         }
 184         if (locks && text) {
 185                 void *lseg = (void *)locks->sh_addr;
 186                 void *tseg = (void *)text->sh_addr;
 187                 alternatives_smp_module_add(me, me->name,
 188                                             lseg, lseg + locks->sh_size,
 189                                             tseg, tseg + text->sh_size);
 190         }
 191
 192         if (para) {
 193                 void *pseg = (void *)para->sh_addr;
 194                 apply_paravirt(pseg, pseg + para->sh_size);
 195         }
 196
 197         /* make jump label nops */
 198         jump_label_apply_nops(me);
 199
 200         return 0;
 201 }
 202
 203 void module_arch_cleanup(struct module *mod)
 204 {
 205         alternatives_smp_module_del(mod);
 206 }